NOTICES

PEOCEBDINGS

MEETINGS OF THE MEMBERS

Eo^al Snstttuttott of #reat Britain,

ABSTRxVCTS OF THE DISCOURSES

DELrV'ERED AT

THE EVENING MEETINGS.

VOLUME XV.
1896—1898.

LONDON:

FEINTED BY WILLIAM CLOWES AND SONS, LIMITED,

STAMFORD STREET AND CHARING CROSS.

1899,

patron*

HBP. MOST GRACIOUS MAJESTY

QUEEN YIGTOEIA.
'feJice-^Patron anti Jgonoratg Mtmttx,

HIS ROYAL HIGHNESS

THE PEINCE OF WALES, E.G. F.E.S.

President — The Duke of Northumberland, K.G, F.S.A.
Treasurer — Sir James Crichton-Browne, M.D. LL.D. F.E.S. — V.P.
Honorary Secretary — Sir Frederick Bramwell, Bart. D.C.L. LL.D.
F.E.S. M.Inst.C.E.— F.P.

Managers, 1899-1900.

Sir Frederick Abel, Bart. K.C.B. D.C.L.

LL.D. F.R.S.
Sir William Crookes, F.R.S.— V.P.
Tlie Duke of Devonshire, K.G. M.A.

D.C.L. LL.D. F.R.S.
The Right Hon. The Earl of Halsbury,

M.A. D.C.L. F.R.S.
Donald William Charles Hood, M.D.

F.R.C.P.
David Edward Hughes. Esq. F.R.S.
The Right Hon. Lord Kelvin, G.C.V.O.

D.C.L. LL.D. F.R.S.— F.P.
Alfred B. Kempe, Esq. M.A. Treas.

R.S.— F.P.
Hugh Leonard, Esq. M. Inst. C.E.
Sir Andrew Noble, K.C.B. F.R.S.—

V.P.
The Right Hon. The Marquis of Salis-
bury, K.G. M.A. D.C.L. LL.D. F.R.S.
Alexander Siemens, Esq. M. Inst. C.E.

—V.P.
Basil Woodd Smith, Esq. F.R.A.S.

F.S.A.
William Hugh Spottiswoode, Esq.

F.C.S.
Sir Henry Thompson, Bart. F.R.C.S.

F.R.A.S.— F.P.

Visitors, 1899-1900.

William Henry Bennett, Esq. F.R.C.S.

Henry Arthur Blyth, Esq. J.P.

Maures Horner, Esq. F.R.A.S.

Edward Kraftmeier, Esq.

Lieut.-Col. Llewellyn Wood Longstaff,
F.R.G.S.

Esq. M.A. LL.D.

Frank McClean,
F.R.S. F.R.A.S.

Henry Francis Makins, Esq. F.R.G.S.

T. Lambert Mears, Esq. M.A. LL.D.

Rudolph Messel, Esq. Ph.D. F.C.S.

Lachlan Mackintosh Rate, Esq. M.A.

John Callander Ross, Esq.

William James Russell, Esq. Ph.D.

F.R.S.

Alfred Gordon Salamon, Esq. F.C.S.
F.I.C.

Sir James Vaughan, B.A. J.P.

John Jewell Vezey, Esq. F.R.M.S.

Professor of Natural PJiilosoj^hj—'rhe Right Hon. Loed Ratleigh, M.A. D.C.L.

LL.D. F.R.S. &c.
Fuller ian Professor of Chemistry — James Dewak, Esq. M.A. LL.D. F.R.S. &c.
FvZlerian Professor of Physiology — E. Ray Lankestek, Esq. M.A. LL.D. F.R.S.

Keeper of the Library and Assistant Secretary — Mr. Henry Young.

Assistant in the Library — Mr. Herbert C. Fyfe.

Assistants in the Laboratories — Mr. R. N. Lennox, F.C.S.

Mr. J. W. Heath, F.C.S. and Mr. G. Gordon.

CONTENTS.

1896.

PAGE

Jan. 17. — The Eight Hon. Lord Rayleigh — More about

Argon .. .. .. ,. ,. .. 1

„ 24. — Professor Burdon Sanderson, M.D. — Ludwig and

Modern Physiology .. .. .. .. 11

„ 31. — Sidney Lee, Esq. — National Biography .. .. 27

Feb. 3.— General Monthly Meeting 32

„ 7. — The Hon. John Collier — Portrait Painting in its

Historical Aspects .. .. .. .. 36

„ 14. — J. J. Armistead, Esq. — Fish Culture .. .. 39

„ 21. — Edward Frankland, Esq. — The Past, Present and

Future Water Supply of London .. .. 53

„ 28. — John Murray, Esq. — Marine Organisms and their

conditions of environment .. .. .. 75

March •2. — General Monthly Meeting 78

„ 6. — ^A. R. BmNiE, Esq. — The Tunnel under the Thames

at Blackwall .. .. .. ., .. 81

„ 13. — William Samuel Lilly, Esq. — The Theory of the

Ludicrous .. .. .. .. .. .. 95

„ 20. — Professor T. E. Eraser, M.D. — Immunisation
against Serpents' Venom, and the Treatment of
Snake-Bite with Antivenene .. .. .. 107

„ 27. — Professor Dewar — New Eesearches on Liquid Air 133

t)

IV CONTENTS.

1896. . PAGE

April 13.— General Monthly Meeting 147

„ 17. — Professor G. Lippmann— Colour Photography .. 151

^^ 24.— Professor G. V. Poore, M.D.— The Circulation of

Organic Matter 157

May 1.— Annual Meeting .. .. .. .. ..175

„ 1.— Colonel H. Watkin, C.B. — Chronographs and

their Application to Gun Ballistics .. .. 176

^^ 4.— General Monthly Meeting 187

,, 8. — Professor Sil7anus P. Thompson — Electric

Shadows and Luminescence ., .. .. 191

^^ 15. — Alexander Siemens, Esq. — Cable Laying on the

Amazon River .. .. .. •• •• 217

„ 22. — Professor J. A. Ewing — Hysteresis .. .. 227

^^ 29. — Augustine Birrell, Esq. M.P.— John Wesley :

Some Aspects of the Eighteenth Century .. 233

June 1.— General Monthly Meeting 235

5.— Professor J. A. Fleming — Electric and Magnetic

Eesearch at Low Temperatures .. .. .. 239

„ 19 (Extra Evening). — Thomas C. Martin, Esq. — The

Utilisation of Niagara .. .. .. .. 269

July 6.— General Monthly Meeting 280

Nov. 2.— General Monthly Meeting 283

Dec. 7.— General Monthly Meeting , 289

1897.

555

Jan. 22. — Professor Dewar — Properties of Liquid Oxygen

29. Professor Jagadis Chunder Bose — The Polariza-
tion of the Electric Ray 293

CONTENTS. ^

1897. PAGE

Feb. 1.— General Monthly Meeting 309

„ 5. — The Eight Eev. The Lord Bishop of London —

The Picturesque in History .. .. .. 313

„ 12. — Peofessoe John Milne — Recent Advances in

Seismology .. .. .. .. .. 326

„ 19. — G. Johnstone Stoney, Esq. — The Approaching

Eeturn of the Great Swarm of November Meteors 337

„ 26. — Lieut.-Col. C. E. Condee — Palestine Exploration 346

March 1.— General Monthly Meeting 350

,5 5. — Shelfoed Bidwell, Esq. — Some Curiosities of

Vision .. .. .. .. .. .. 354

„ 12. — Peofessoe Aethub Smithells — The Source of

Light in Flames .. .. .. .. .. 366

„ 19. — SiE Edwaed Maundb Thompson, K.C.B. — Greek

and Latin Palaeography .. .. .. .. 375

„ 26.— SiE William Tuenee — Early Man in Scotland .. 391

April 2. — Chaeles T. Hetcock, Esq. — Metallic Alloys and

the Theory of Solution 409

„ 5.— General Monthly Meeting 413

„ 9. — The Eight Hon. Loed Eatleigh — The Limits of

Audition 417

„ 30. — Peofessoe J. J. Thomson— Cathode Eays .. 419

May 1. — Annual Meeting .. .. .. .. .. 433

^^ 3.— General Monthly Meeting 434

„ 7. — Anthony Hope Hawkins, Esq. — Eomance .. 438

„ 14. — Peofessoe Haeold Dixon — Explosion-Flames .. 451

„ 21. — The Eight Hon. Loed Kelvin — Contact Elec-
tricity of Metals .. .. .. .. .. 521

28.— Peofessoe H. Moissan — Le Fluor .. .. 462

Vl CONTENTS.

1897. '^^^^

June 4. — W. H. Preece, Esq. — Signalling through Space
without Wires

467
477
502
508
511
517

„ 11. — William Crookes, Esq. — Diamonds

„ 14. — General Monthly Meeting ..
July 5. — General Monthly Meeting ..
Nov. 1.— General Monthly Meeting ..
Dec. 6.— General Monthly Meeting ..

1898.

Jan. 21.— The Eight Hon. Sir John Lubbock, Bart. M.P.—

Buds and Stipules.. .. .. .. .. 565

„ 28. — Professor C. Lloyd Morgan — Instinct and Intelli-
gence in Animals .. .. .. .. .. 567

Yeb. 4. — Alan A. Campbell Swinton, Esq. — Some New

Studies in Cathode and Eontgen Eadiations .. 580

^^ 7.— General Monthly Meeting 602

„ 11. — John Hall Gladstone, Esq. — The Metals used by

the -Great Nations of Antiquity .. .. .. 608

„ 18. — Professor L. C. Miall — A Yorkshire Moor .. 621

„ 25. — Captain Abney, C.B. — The Theory of Colour

Vision applied to Modern Colour Photography .. 802

March 4. — Professor T. E. Thorpe— Some Eecent Eesults of

Physico-Chemical Inquiry .. .. .. 641

„ 7.— General Monthly Meeting 660

^^ 11. — Walter Frewen Lord, Esq. — "Marked Unex-
plored" 664

„ 18. — James Mansergh, Esq. — The Bringing of Water to

Birmingham from the Welsh Mountains .. 679

CONTENTS. Vll

1898. PAGE

March 25. — The Very Eev. The Dean of Canterbury, D.D.

— Canterbury Cathedral .. .. .. .. 698

April 1. — Professor Dewar — Liquid Air as an Analytic

Agent 815

„ 4— General Monthly Meeting 699

„ 22.— W. H. M. Christie, Esq. C.B.— The Recent

Eclipse .. 810

„ 29. — Professor Andrew Gray — Magneto-Optic Rota-
tion and its Explanation by a Gyrostatic Medium 703

May 2.— Annual Meeting 722

„ 6. — Edward A. Minchin, Esq. — Living Crystals .. 723

„ 9.— General Monthly Meeting .. .. .. ..732

„ 13. — Professor W. A. Tilden — Recent Experiments
on Certain of the Chemical Elements in relation

to Heat .. .. 735

„ 20.— The Right Hon. D. H. Madden— The Early Life

and Work of Shakespeare .. .. .. 743

„ 27. — Lieut.-General The Hon. Sir Andrew Clarke

— Sir Stamford Raffles and the Malay States .. 754

June 3. — Professor W. M. Flinders Petrie — The Develop-
ment of the Tomb in EgyjDt 769

„ 6.— General Monthly Meeting ,. 783

„ 10. — The Right Hon. Lord Rayleigh — Some Experi-
ments with the Telephone .. .. .. 786

July 4.— General Monthly Meeting 789

Nov. 7. — General Monthly Meeting 793

Dec. 5. — General Monthly Meeting 799

Index to Volume XV 830

PLATES.

PAGE

Illustrations on Fish Culture— Figs. 1, 3, 5, 6, 7, 8 .. 43, 47, 50
Microbes in Water— Figs. 6 to 11, 17 to 22 .. .. 61,73

Laboratory Liquefaction Apparatus — Fig. 1 .. .. .. 144

Liquid Ethylene-Flame Calorimeter — Fig. 2 .. .. .. 144

Lecture Apparatus for Projecting the Liquefaction of Air —

Fig. 3 144

Plan of Comparing Temperatures of Liquefaction and Small

Vapour Pressure — Fig. 4 .. .. .. .. .. 144

Specific Gravity Vacuum Globe — Fig. 5 .. .. .. 144

Arrangements of Regenerating Coils — Fig. 6 .. .. .. 144

Apparatus for Measuring Passage of Gas — Fig. 7 .. .. 144

Apparatus Used in Production of the Liquid Hydrogen Jet —

Fig. 8 144

Chart, Electrical Resistivity and Temperature . . .. .. 249

Chart, Thermo-Electromotive Forces .. .. .. ..259

Niagara Turbines .. .. .. .. .. -. .. 273

Illustrations on Diamonds and Diamond Mines — Figs. 1 to 30

478, 480, 482, 484, 486, 496, 500

Cathode Ray Spectrum .. .. .. .. .. .. 689

Results obtained with Anti-Cathodes, &c. .. .. 591, 593

Pin-Hole Rontgen Ray Photographs .. .. .. .. 598

Diagrams to Illustrate the Bringing of Water to Birmingham

— Figs. 1 to 11 681 to 689

Illustrations to Theory of Colour Vision applied to Modern

Colour Photography .. .. .. .. .. ,. 805

Eonal lustttution of ©reat Britaiii<$>/6* ^♦;V.

I^^i^ -ifc.d^ ^♦N'^;

WEEKLY EVENING MEETING, \lJ\ ^^•-'►^ ^^

Friday, January 17, 1896. ^'•^"^^^f*

Sir Frederick Abel, Bart. K.C.B. D.C.L. LL.D. F.R.s!
Vice-President, in the Chair.

The Right Hon. Lord Rayi.eigh, M.A. D.C.L. LL.D. F.R.S.
31B.L Professor of Natural Philosophy R.I.

3Iore about Argon.
(Abstract.)

In our original paper* are described determinations by Professor
Ramsay, of the density of argon prepared with the aid of magnesium.
The volume actually weighed was 163 c.c. and the adopted mean
result was 19 '941, referred to O., = 16. At that time a satisfactory
conclusion as to the density of argon prepared by the oxygen method
of Cavendish had not been reached, although a preliminary result
(19*7) obtained from a mixture of argon and oxygen "j" went far to
show that the densities of the gases prepared by the two methods
were the same. In order further to test the identity of the gases, it
was thought desirable to pursue the question of density ; and I deter-
mined, as the event proved, somewhat rashly, to attempt large scale
weighings of pure argon with the globe of 1800 c.c. capacity
employed in former weighings of gases J which could be obtained in
quantity.

The accumulation of the 3 litres of argon, required for convenient
working, involved the absorption of some 300 litres of nitrogen, or
about 800 litres of the mixture with oxygen. This was effected at
the Royal Institution with the apparatus already described, § and
which is capable of absorbing the mixture at the rate of about
7 litres per hour. The operations extended themselves over nearly
three weeks, after which the residual gases amounting to about
10 litres, still containing oxygen with a considerable quantity of
nitrogen, were removed to the country and transferred to a special
apparatus where it could be prepared for weighing.

For this purpose the purifying vessel had to be arranged some-
what differently from that employed in the preliminary absorption

* Rayleigh and Ramsay, Phil. Trans, vol. 186 A, pp. 221, 238, 1895.
t Loc. cit. p. 221.

X Roy. Soc. Proc. February 1888 ; February 1892 ; March 1893.
§ Phil. Trans, loc. cit. p. 219.

Vol. XV. (No. 90.) b

2 Lord Bayleigh, [Jan. 17,

of nitrogen. Wlien the gas is withdrawn for weighing, the space left
vacant must be filled up with liquid, and afterwards when the gas is
brought back for repurification, the liquid must be removed. In
order to effect this the working vessel (Fig. 7*) communicates by
means of a siphon with a 10-litre "aspirating bottle," the ends of
the siphon being situated in both cases near the bottom of the liquid.
In this way the alkaline solution may be made to pass backwards
and forwards, in correspondence with the desired displacements of
gas.

There is, however, one objection to this arrangement which requires
to be met. If the reserve alkali in the aspirating bottle were allowed
to come into contact with air, it would inevitably dissolve nitrogen,
and this nitrogen would be partially liberated again in the working
vessel, and so render impossible a complete elimination of that gas
from the mixture of argon and oxygen. By means of two more
aspirating bottles an atmosphere of oxygen was maintained in the
first bottle, and the outermost bottle, connected with the second by a
rubber hose, gave the necessary control over the pressure.

Five glass tubes in all were carried through the large rubber cork
by which the neck of the working vessel was closed. Two of these
convey the electrodes : one is the siphon for the supply of alkali,
while the fourth and fifth are for the withdrawal and introduction of
the gas, the former being bent up internally, so as to allow almost
the whole of the gaseous contents to be removed. The fifth tube, by
which the gas is returned, communicates with the fall-tube of the
Topler pump, provision being made for the overflow of mercury. In
this way the gas, after weighing, could be returned to the working
vessel at the same time that the globe was exhausted. It would be
tedious to describe in detail the minor arrangements. Advantage
was frequently taken of the fact that oxygen could always be added
with impunity, its presence in the working vessel being a necessity
in any case.

When the nitrogen had been so far removed that it was thought
desirable to execute a weighing, the gas on its way to the globe had
to be freed from oxygen and moisture. The purifying tubes contained
copjier and copj^er oxide maintained at a red heat, caustic soda, and
phosphoric anhydride. In all other respects the arrangements were
as described in the memoir on the densities of the principal gases,|
the weighing globe being filled at 0°, and at the pressure of the
manometer gauge.

The i^rocess of purification with the means at my command proved
to be extremely slow. The gas contained more nitrogen than had
been expected, and the contraction went on from day to day until
I almost desj^aired of reaching a conclusion. But at last the visible
contraction ceased, and soon afterwards the yellow line of nitrogen

* Phil. Trans, loc. cit. p. 218.

t Roy. Soc. Proc. vol. 53, p. 134, 1893.

1896.] More about Argon. ' 3

disappeared from the spectrum of the jar discharge.* After a little
more sparking, a satisfactory weighing was obtained on May 22,
1895 ; but, in attempting to repeat, a breakage occurred, by which a
litre of air entered, aad the whole process of purification had to be
recommenced. The object in view was to effect, if possible, a series
of weighings with intermediate sparkings, so as to obtain evidence
that the purification had really reached a limit. The second attempt
was scarcely more successful, another accident occurring when two
weighings only had been completed. Ultimately a series of four
weighings were successfully executed, from which a satisfactory con-
clusion can be arrived at.

May 22 „ 3-2710

June 4 3-2617

June 7 3-2727

June 13 3-2652

June 18 3-2750)

June 25 3-2748 3-2746

July 2 3-2741)

The results here recorded are derived from the comparison of
the weighings of the globe " full " with the mean of the preceding
and following weighings " empty," and they are corrected for the
errors of the weights and for the shrinkage of the globe when
exhausted, as explained in former papers. In the last series, the
experiment of June 13 gave a result already known to be too low.
The gas was accordingly sparked for fourteen hours more. Between
the weighings of June 18 and June 25 there was nine hours' spark-
ing, and between those of June 25 and July 2 about eight hours'
sparking. The mean of the last three, viz. 3-2746, is taken as the
definitive result, and it is immediately comparable with 2-6276, the
weight under similar circumstances of oxygen.f If we takeOa = 16,
we obtain for argon

19-940,

in very close agreement with Professor Ramsay's result.

The conclusion from the spectroscopic evidence that the gases
isolated from the atmosphere by magnesium and by oxygen are
essentially the same is thus confirmed.

The refractivity of argon was next investigated, in the hope that
it might throw some light upon the character of the gas. For this

* Jan. 29. — When the argon is nearly pin-e, the arc discharge (no jar connected)
assumes a peculiar purplish colour, quite distinct from the greenish" hue apparent
while the oxidation of nitrogen is iu progress and from the sky blue observed
when the residue consists mainly of oxygen.

t Roy. Soc. Proc. vol. 53, p. 144, 1893.

b2

4 Lord Bayleigh, [Jan, 17,

purpose absolute measurements were not required. It sufficed to
compare the pressures necessary in two columns of air and argon of
equal lengths, in order to balance the retardations undergone by
light in traversing them.

The arrangement was a modification of one investigated by
Fraunhofer, depending upon the interference of light transmitted
through two parallel vertical slits placed in front of the object-
glass of a telescope. If there be only one slit, and if the original
source, either a distant point or a vertical line of light, be in focus,
the field is of a certain width, due to "diffraction," and inversely
as the width of the slit. If there be two equal parallel slits whose
distance apart is a consitlerable multiple of the width of either, the
field is traversed by bands of width inversely as the distance between
the slits. If from any cause one of the portions of light be retarded
relatively to the other, the bands are displaced in the usual manner,
and can be brought back to the original position only by abolishing
the relative retardation.

When the object is merely to see the interference bands in full
perfection, the use of a telescope is not required. The function of
the telescope is really to magnify the slit system,* and this is neces-
sary when, as here, it is desired to operate separately uj^on tlie two
portions of light. The apparatus is, however, extremely simple, the
principal objection to it being the high magnifying power required,
leading under ordinary arrangements to a great attenuation of light.
I have found that this objection may be almost entirely overcome by
the substitution of cylindrical lenses, magnifying in the horizontal
direction only, for the spherical lenses of ordinary eye-pieces. For
many purposes a single lens suihces, but it must be of high power.
In tiie measurements about to be described most of the magnifying
was done by a lens of home manufacture. It consisted simply of a
round rod, about ^ inch (4 mm.) in diameter, cut by Mr. Gordon from
a piece of plate glass.j This could be used alone ; but as at first it
was thought necessary to have a web, serving as a fixed mark to
which the bands could be referred, the rod was treated as the object-
glass of a compound cylindrical microscope, the eye-j^iece being a
commercial cylindrical L ns of IJ inch (31 mm.) focus. Both lenses
were mounted on adjustable stands, so that the cylindrical axes could
be made accurately vertical, or, rather, accurately 2>arallel to the
length of the original slit. The li<iht from an ordinary paraffin lamp
now sufficed, although the magnification was such as to allow the
error of setting to be less than 1/20 of a band interval. It is to
be remembered that with this arrangement the various parts of
the length of a band correspond, not to the various parts of the
original slit, but rather to the various parts of the object-glass. This

* Brit. Assoc. Keport, 1893, p. 703,

t Preliminary experiments liad been made with ordinary glass cane and with
tubes charged with water.

1896.]

More about Argon.

departure from the operation of a spherical eye-piece is an
advantage, inasmuch as optical defects show themselves by deformation
of the bands instead of by a more injurious encroachment upon the
distinction between the dark and bright parts.

The collimating lens A (Fig. 1) is situated 23 feet (7 metres)
from the source of light. B, C are the tubes, one containing dry air,
the other the gas to be experimented upon. They are 1 foot
(30-5 cm.) long, and of J inch (1*3 cm.) bore, and they are closed at
the ends with small plates of parallel glass cut from the same strip.
E is the object-glass of the telescope, about 8 inches (7*6 cm.) in
diameter. It is fitted with a cap D, perforated by two parallel slits.
Each slit is ^ inch (6 mm.) wide, and the distance between the
middle lines of the slits is 1 J inches (38 mm.).

The arrangements for charging the tubes and varying the pres-
sures of the gases are sketched in Fig. 2. A gas pipette, D E, com-
municates with the tube C, so that by motion of the reservoir E and
consequent flow of mercury through the connecting hose, part of the
gas may be transferred. The pressure was measured by a U-shaped

n ji

tfc

Fig. 1.

manometer F, containing mercury. This was fitted below with
a short length of stout rubber tubing G, to which was applied a
squeezer H. The object of this attachment was to cause a rise of
mercury in both limbs immediately before a reading, and thus to
avoid the capillary errors that would otherwise have entered. A
similar pipette and manometer were connected with the air tube B.
In order to be able, if desired, to follow with the eye a particular
band during the changes of pressure (effected by small steps and
alternately in the two tubes), diminutive windlasses were provided by
which the motions of the reservoirs (E) could be made smooth and
slow. In this way all doubt was obviated as to the identity of a
band ; but after a little experience the precaution was found to be
unnecessary.

The manner of experimenting will now be evident. By adjustment
of pressures the centre of the middle band was brought to a definite
position, determined by the web or otherwise, and the pressures were
measured. Both pressures were then altered and adjusted until the
band was brought back precisely to its original position. The ratio
of the changes of pressure in the inverse ratio of the refractivities

6

Lord Bayleigh,

[Jan. 17,

(/A = 1) of tlie gases. The process may be repeated backwards and
forwards any number of times, so as to eliminate in great degree
err ors of the settings and of the pressure readings.

During these observations a curious effect was noticed, made
possible by the independent action of the parts of the object-glass
situated at various levels, as already referred to. When the bands
were stationary, they appeared straight, or nearly so, but when in
motion, owing to changes of pressure, they became curved, even in
passing the fiducial position, and always in such a manner that the

I^.

To pump.

Scale = 4

Fig. 2.

ends led. The explanation is readily seen to depend upon the
temporary changes of temperature which accompany compression or
rarefaction. The full effect of a compression, for example, would not
be attained until the gas had cooled back to its normal temperature,
and this recovery of temperature would occur more quickly at the
top and bottom, where the gas is in proximity to the metal, than in the
central part of the tube.

The success of the measures evidently requires that there should
be no apparent movement of the bands apart from real retardations

1896.] More about Argon. 7

in the tubes. As the apparatus was at first arranged, this condition
was insufficiently satisfied. Although all the parts were carried upon
the walls of the room, frequent and somewhat sudden displacements
of the bands relatively to the web were seen to occur, probably in
consequence of the use of wood in some of the supports. The obser-
vations could easily be arranged in such a manner that no systematic
error could thence enter, but the agreement of individual measures
was impaired. Subsequently a remedy was found in the use of a
second system of bands, formed by light w^hich passed just above the
tubes, to which, instead of to the web, the movable bands were referred.
The coincidence of the two systems could be observed with accuracy,
and was found to be maintained in spite of movements of both rela-
tively to the web.

In the comparisons of argon and air (with nearly the same re-
fractivities) the changes of pressure employed were about 8 inches
(20 cm.), being deductions from the atmospheric pressure. In one
observation of July 26, the numbers, representing suctions in inches
of mercury, stood

Argon. Air.

.8-54 99-6

0-01 1*77

8-63 8-19

Ratio = 0-961,

signifying that 8 '53 inches of argon balanced 8*19 inches of dry
air. Four sets, during which the air and argon (from the globe as
last filled for weighing) were changed, taken on July 17, 18, 19, 26,
gave respectively for the final ratio 0*962, 0*961, 0*961, 0*960, or as
the mean

Eefractivity of argon

Eefractivity of air

= 0*961.

The evidence from the refractivities, as well as from the weights,
is very unfavourable to the view that argon is an allotropic form of
nitrogen such as would be denoted by N3.

The above measurements, having been made with lamp-light, refer
to the most luminous region of the spectrum, say in the neighbour-
hood of D. But since no change in the appearance of the bands at
the two settings could be detected, the inference is that the dis-
persions of the two gases are approximately the same, so that the
above ratio would not be much changed, even if another part of the
spectrum were chosen. It may be remarked that the displacement
actually compensated in the above experiments amounted to about forty
bands, each band corresponding to about ^ inch (5 mm.) pressure of
mercury.

Similar comparisons have been made between air and helium.

8 Lord Bayleigh, [Jan, 17,

The latter gas, prepared by Professor Eamsay, was brought from
London by Mr. W. Randall, who further gave valuable assistance in
the manipulations. It appeared at once that the refractivity of
helium was remarkably low, 13 inches pressure of the gas being
balanced by less than 2 inches pressure of air. The ratios given by
single comparisons on July 29 were 0* 14.7, 0*146, 0*145, 0*146,
mean 0*146; and on July 30, 0*147, 0* 147, 0*145, 0* 145, mean
0*146. The observations were not made under ideal concUtions, on
account of the smallness of the changes of air pressure ; but we may
conclude that with considerable approximation

Refractivity of helium

Refractivity of air

= 0*146.

The lowest refractivity previously known is that of hydrogen,
nearly 0 * 5 of that of air.

The viscosity was investigated by the method of passage through
capillary tubes. The approximate formula has been investigated by
O. Meyer,* on the basis of Stokes' theory for incompressible fluids.
If the driving pressure (p^ — ^2) is not too great, the volume Vg
delivered in time t through a tube of radius R and length A. is given

by

the volume being measured at the lower pressure ^.,5 ^^^ V denoting
the viscosity of the gas. In the comparison of different gases Vg, Pi-,
^2) Rj ^ Diay be the same, and then 7/ is proportional to t.

In the apparatus employed two gas pipettes and manometers,
somewhat similar to those shown in Fig. 2, were connected by a
capillary tube of very small bore and about 1 metre long. The
volume V2 was about 100 c.c. and was caused to pass by a pressure
of a few centimetres of mercury, maintained as uniform as possible
by means of the pipettes. There was a difficulty, almost inherent in
the use of mercury, in securing the right pressures during the first
few seconds of an experiment ; but this was not of much importance
as the whole time t amounted to several minutes. The ajjparatus was
tested upon hydrogen, and was found to give the received numbers
with sufficient accuracy. The results, referred to dry air, were for
helium 0*96; and for argon 1*21, somewhat higher than for
oxygen which at present stands at the head of the list of the principal

In the original memoir upon argon | results were given of
weighings of the residue from the Bath gas after removal of oxygen,
carbonic anhydride, and moisture, from which it appeared that the

* Pogg. Ann. vol. 127, p. 270, 1866.

t Rayleigh and Ramsay, Phil. Trans. A, vol. 186, p. 227. 1895.

1896.] More about Argon. 9

proportion of argon was only one-half of that contained in the
residue, after similar treatment from the atmosj^here. After the
discovery of helium by Professor Kamsay, the question presented
itself as to whether this conclusion might not be disturbed by the
presence in the Bath gas of helium, whose lightness would tend to
compensate the extra density of argon.

An examination of the gas which had stood in my laboratory more
than a y^ar having shown that it still contained no oxygen, it was
thought worth while to remove the nitrogen so as to determine the
proportion that would refuse oxidation. For this purpose 200 c.c.
were worked up with the oxygen until the volume, free from nitrogen,
was reduced to 8 c.c. On treatment with pjrogallol and alkali the
residue measured 3 • 3 c.c. representing argon, and helium, if j^resent.
On sparking the residue at atmospheric pressure and examining the
spectrum, it was seen to be mainly that of argon, but with an un-
mistakable exhibition of D3. At atmospheric pressure this line
appears very diffuse in a spectroscope of rather high power, but the
place was correct.

From another sample of residue from the Bath gas, vacuum tubes
were charged by my son, Mr. R. J. Strutt, and some of them showed
D3 sharply defined and precisely coincident with the line of helium
in a vacuum tube prepared by Professor Earn say.

Although the presence of helium in the Bath gas is not doubtful,
the quantity seems insufficient to explain the low density found in
October 1894. In order to reconcile that density with the proportion
of residue (8-3/200 = 0*016) found in the experiment just described,
it would be necessary to suppose that the helium amounted to 25 per
cent, of the whole residue of argon and helium. Experiment, how-
ever, proved that a mixture of argon and helium containing 10 per
cent, of the latter gas showed D3 more plainly than did the Bath
residue. It is just possible that some of the helium was lost by
diffusion during the long interval between the experiments whose
results are combined in the above estimate.

Gas from the Buxton springs, kindly collected for me by
Mr. A. McDougall, was found to contain no appreciable oxygen.
The argon amounted to about 2 per cent, of the volume. When its
spectrum was examined, the presence of D3 was suspected, but the
appearance was too feeble to allow of a definite statement being made.
The proportion of helium is in any case very much lower than in the
Bath gas.

Is helium contained in the atmosphere? Apart from its
independent interest, this question is important in connection with
the density of atmospheric argon. Since the spectrum of this gas
does not show the line D3, we may probably conclude that the pro-
portion of heliuin is less than 3 per cent. ; so that there would be less
than 3 x 10"^ of helium in the atmosphere. The experiment about
to be described was an attempt to carry the matter further, and is
founded upon the observation by Professor Ramsay, that the solu-

10 More about Argon. [Jan. 17,

bility of helium in water is only 0 * 007, less than one-fifth of that
which we found for argon.*

It is evident that if a mixture of helium and argon be dissolved
in water until there is only a small fraction remaining over, the
proportion of helium will be much increased in the residue. Two
experiments have been made, of which that on October 6, 1805,
was the more elaborate. About 60 c.c. of argon were shaken for
a long time with well boiled water contained in a large flask.
When the absorption had ceased, the residue of 30 c.c. was sparked
with a little oxygen until no nitrogen could be seen in the spec-
trum. It was then treated a second time with boiled water until its
volume was reduced to 1 J c.c. With this vacuum tubes were charged
by my son at two different pressures. In none of them could D3 be
detected ; nor was there any marked difference to be seen between
the spectra of the washed and the unwashed argon. If helium be
present in the atmosphere, it must be in very small quantity, pro-
ably much less than a ten-thousandth part.

* Phil. Trans. A, vol. 18G, p. 225, 1895.

1896.] Ludwig and Modern Physiology. 11

WEEKLY EVENING MEETING,

Friday, January 24, 1896.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Professor Burdon Sanderson, M.D. D.C.L. LL.D. F.E.S.

Ludwig and Modern Physiology.

The death of any discoverer — of any one who has added largely to
the sum of human knowledge, affords a reason for inquiring what
his work was and how he accomplished it. This inquiry has interest
even when the work has been completed in a few years and has been
limited to a single line of investigation — much more when the life
has been associated with the origin and development of a new science
and has extended over half a century.

The Science of Physiology as we know it came into existence
fifty years ago with the beginning of the active life of Ludwig, in
the same sense that the other great branch of Biology, the Science
of Living Beings, as we now know it, came into existence with the
appearance of the ' Origin of Species.' In the order of time
Physiology had the advantage, for the new Physiology was accepted
some ten years before the Darwinian epoch. Notwithstanding, the
content of the Science is relatively so unfamiliar, that before entering
on the discussion of the life and work of the man who, as I shall
endeavour to show, had a larger share in founding it than any of his
contemporaries, it is necessary to define its limits and its relations
to other branches of knowledge.

The word Physiology has in modern times changed its meaning.
It once comprehended the whole knowledge of Nature. Now it is
the name for one of the two Divisions of the Science of Life. In
the progress of investigation the study of that Science has inevitably
divided itself into two : Ontology,^ the Science of Living Beings ;
Physiology, the Science of Living Processes, and thus, inasmuch as
Life consists in processes, of Life itself. Both strive to understand
the complicated relations and endless varieties which present them-
selves in living Nature, but by different methods. Both refer to
general principles, but they are of a different nature.

To the Oniologist, the student of Living Beings, Plants or

* I do not forget that this word is ordinarily used in another sense. Its
suitability is my excuse for employing it.

12 Professor Burdon Sanderson [Jan. 24,

Animals, the great fact of Evolution, namely, that from the simplest
beginning our own organism, with its infinite comj^lication of parts
and powers, no less than that of every animal and plant, unfolds the
plan of its existence — taken with the observation that that small
beginning was, in all excepting the lowest forms, itself derived from
two parents, equally from each— is the basis from which his study
and knowledge of the world of living beings takes its departure.
For on Evolution and Descent the explorer of the forms, distribution
and habits of animals and plants has, since the Darwinian epoch,
relied with an ever-increasing certainty, and has found in them the
explanation of every phenomenon, the solution of every problem
relating to the subject of his inquiry. Nor could he wish for a more
secure basis. Whatever doubts or misgivings exist in the minds of
" non-biologists " in relation to it, may be attributed partly to the
association with the doctrine of Evolution of questions which the
true naturalist regards as transcendental ; partly to the perversion or
weakening of meaning which the term has suffered in consequence of
its introduction into the language of common life, and particularly
to the habit of applying it to any kind of progress or improvement,
anything which from small beginnings gradually increases. But,
provided we limit the term to its original sense — the Evolution of
a livin^^ being from its germ by a continuous not a gradual process,
there is no conception which is more free from doubt either as to
its meaning or reality. It is inseparable from that of Life itself,
which is but the unfolding of a predestined harmony, of a prearranged
consensus and synergy of parts.

The other branch of Biology, that with which Ludwig's name
is associated, deals with the same facts in a different way. While
Ontology regards animals and plants as individuals and in relation
to other individuals. Physiology considers the processes themselves
of which life is a complex. This is the most obvious distinction,
but it is subordinate to the fundamental one, namely, that while
Ontology has for its basis laws which are in force only in its own
province, those of Evolution, Descent, and Adaptation, we Physio-
logists, while accepting these as true, found nothing upon them,
using them only as guides to discovery, not for the purpose of
explanation. Purposive Adaptation, for example, serves as a clue,
by which we are constantly guided in our exploration of the tangled
labyrinth of vital processes. But when it becomes our business to
explain these processes — to say how they are brought about — we
refer them not to biological principles of any kind, but to the
Universal Laws of Kature. Hence it happens that with reference
to each of these processes, our inquiry is rather how it occurs than
why it occurs.

It has been well said that the Natural Sciences are the children
of necessity. Just as the other Natural Sciences owed their origin
to the necessity of acquiring that control over the forces of Nature
without which life would scarcely be worth living, so Physiology

1896.] on Ludicig and Modern Physiology. 13

arose out of human suffering and the necessity of relieving it. It
sprang indeed out of Pathology. It was suffering that led us to
know, as regards our own bodies, that we had internal as well as
external organs ; and probably one of the first generalisations
which arose out of this knowledge was, that " if one member suffer
all the members suffer with it " — that all work together for the good
of the whole. In earlier times the good which was thus indicated
was associated in men's minds with human welfare exclusively. But
it was eventually seen that Nature has no less consideration for the
welfare of those of her products which to us seem hideous or mis-
chievous, than for those which we regard as most useful to man
or most deserving of his admiration. It thus became apj)arent that
the good in question could not be human exclusively, but as regards
each animal its own good — and that in the organised world the
existence and life of every sj^ecies is brought into subordination to
one purpose — its own success in the struggle for existence.*

From what has preceded it may be readily understood that in
Physiology, Adaptation takes a more prominent part than Evolution
or Descent. In the prescientific period adaptation was everything.
The observation that any structure or arrangement exhibited marks
of adaptation to a useful purpose was accepted not merely as a guide
in research, but as a full and final explanation. Of an organism or
organ which perfectly fulfilled in its structure and working the end
of its existence, nothing further required to be said or known.
Physiologists of the present day recognise as fully as their pre-
decessors that perfection of contrivance which displays itself in all
living structures, the more exquisitely the more minutely they are
examined. No one, for example, has written more emphatically on
this point than did Ludwig. In one of his discourses, after showing
how Nature exceeds the highest standard of human attainment — how
she fashions as it were out of nothing and without tools, instruments
of a perfection which the human artificer cannot reach, though
provided with every suitable material — wood, brass, glass, india-
rubber — he gives the organ of sight as a single example, referring
among its other perfections to the rapidity with which the eye can
be fixed on numerous objects in succession, and the instantaneous
and unconscious estimates which w^e are able to form of the distances
of objects, each estimate involving a process of arithmetic which no

* I am aware that in thus stating the relation between adaptation and
the struggle for existence, I may seem to be reversing the order followed by
Mr. Darwin, insomuch as he regarded the survival of organisms which are fittest
for their place in Nature, and of parts which are fittest for their place in the
organism, as the agency by which adaptedness is brought about. However this
may be expressed, it cannot be doubted that fitness is an essential property of
organisms. Living beings are the only things in Nature which by virtue of
evolutijn and descent are able to adapt themselves to their surroundings. It
is therefore only so far as organism (with all its attributes) is presupposed, that
the dependence of adaptation on survival is intelligible.

14 Professor Burden Sanderson [Jan. 24,

calculating machine could effect in the time.* In another discourse
— that given at Leipzig when lie entered on liis professorship in 1865,
he remarks that when in our researches into the finer mechanism of
an organ we at last come to understand it, we are humbled by the
recognition " tliat the human inventor is but a blunderer compared
with the unknown Master of the animal creation." "j"

Some readers will perhaps remember how one of the most
brilliant of jDliilosophical writers, in a discourse to the British
Association delivered a quarter of a century ago, averred on the
authority of a great Physiologist that the eye, regarded as an optical
instrument, was so inferior a production that if it were the work of
a mechanician it would be unsaleable. Without criticising or
endeavouring to exjjlain this paradox, I may refer to it as having
given the countenance of a distinguished name to a misconception
which I know exists in the minds of many jiersons, to the eft'ect that
the scientific Physiologist is more or less blind to the evidence of
design in creation. On the contrary, the view taken by Ludwig, as
expressed in the words I have quoted, is that of all Physiologists.
The disuse of the tcleological expressions which were formerly
current does not imply that the indications of contrivance are less
appreciated, for, on the contrary, we regard them as more character-
istic of organism as it presents itself to our observation than any
other of its enrlowments. But, if I may be permitted to repeat what
has been already said, we use the evidences of adaptation dilFerently.
We found no explanation on this or any other biological principle,
but refer all the phenomena by which these manifest themselves, to
the simpler and more certain Pliysical Laws of the Universe.

Why must we take this position? First, because it is a general
rule in investigations of all kinds, to explain the more complex by the
more simple. The material Universe is manifestly divided into two
parts, the living and the non-living. We may, if we like, take the
living as our Norma, and say to the Physicists, you must come to us
for Laws, you must account for the i)lay of energies in universal
nature by referring them to Evolution, Descent, Adaptation. Or wo
may take these words as true expressions of the mutual relations
between the phenomena and processes peculiar to living beings,
using for the explanation of the processes themselves the same
methods which we should employ if we were engaged in the investi-
gation of analogous processes going on independently of life. Between
these two courses there seems to me to be no third alternative, unless we

* I summarise here from a very interesting lecture entitled "Leid und
Frcude in der Naturforschung " published iu the ' Gartenlaube ' (Nos. 22 and
23) in 1870.

t 'i'he sentence, of which the words in inverted commas form a part, is as
follows : " "NVenn uns endlich die Palme gereiclit wird, wenn wir ein Organ in
scinora Zuzammenhang begreifen, so wild unser stolzes Gattungsbcwnsstsein
durch die Erkenntniss niedergodriickt, dass der mcnsolilielier Erfinder cin
Stumper gegcn den uubekaimtou Mcister der thicrischcu Schopfung sei."

189G.] on Ludwig and Modern Phi/siology. 16

suppose that tliere are two material Universes, one to wliicli the
material of our bodies belongs, the other comprising everything that
is not either plant or animal.

The second reason is a practical one. We should have to go back
to the time which I have ventured to call prescientific, when the
world of life and organisation was supposed to be governed ex-
clusively by its own Laws. The work of the past fifty years has been
done on the opposite principle, and has brought light and clearness
where there was before obscurity and confusion. All this progress
we should have to repudiate, but this would not be all. We should
have to forego the prospect of future advance. Whereas by holding
on our present course, gradually proceeding from the more simple to
the more complex, from the physical to the vital, we may confidently
look forward to extending our knowledge considerably beyond its
present limits.

A no less brilliant writer than the one already referred to, who is
also no longer with us, asserted that mind was a secretion of the brain
in the same sense that bile is a secretion of the liver, or urine that of
the kidney ; and many people have imagined this to be the necessary
outcome of a too mechanical way of looking at vital phenomena, and
that Physiologists, by a habit of adhering strictly to their own
method, have failed to see that the organism presents j^roblems to
which this method is not applicable, such e.g. as the origin of the
organism itself, or the origin and development in it of the mental
faculty. The answer to this suggestion is that these questions are
approached by Physiologists only in so far as they are ai)proacliable.
We are well aware that our business is with the unknown knowable,
not with the transcendental.

During the last twenty years there has been a considerable
forward movement in Physiology in the psychological direction,
partly dependent on discoveries as to the localisation of the higher
functions of the nervous system, partly on the application of methods
of measurement to the concomitant phenomena of psychical processes.
And these researches have brought us to the very edge of a region
which cannot be explored by our methods — where measurements of
time or of sj^ace are no longer possible. In approaching this limit,
the Physiologist is liable to fall into two mistakes — on the one hand
that of passing into the transcendental without knowing it ; on the
other, that of assuming that what he does not know is not knowledge.
The former of these risks seems to me of little moment ; first, because
the limits of natural knowledge in the psychological direction have
been well defined by the best writers, as e.g. by du Bois-Eeymond in
his well-known essay " On the Limits of Natural Knowledge," * but
chiefly because the investigator who knows what he is about is
arrested in limine by the impossibility of applying the experimental

Ucbcr die Grenzeu des Natureikeunens.' Rcden, Leipzig, 188G.

16 Professor Burdon Sanderson [Jan. 24,

method to questions beyond its scope. The other mistake is chiefly
fallen into by careless thinkers who, while they object to the employ-
ment of intuition even in regions where intuition is the only method
by which anything can be learned, attempt to describe and define
mental processes in mechanical terms, assigning to these terms mean-
ings which science does not recognise, and thus slide into a kind of
speculation which is as futile as it is unphilosophical.

Ludwig as Investigator and Teacher.

The uneventful history of Ludwig's life — how early he began his
investigation of the anatomy and function of the kidneys, how lie
became just fifty years ago titular Professor at Marburg, in the small
University of his native State, Hesse Cassel ; how in 1849 he
removed to Zurich as actual Professor and thereupon married ; how
he was six years later promoted to Vienna, h;is already been admir-
ably related by Dr. Stirling.* In 1865, after twenty years of
professorial experience, but still in the prime of life and, as it
turned out, with thirty years of activity still before him, he accepted
the Chair of Physiology at Leipzig. His invitation to that great
University was by far the most important occurrence in his life, for
the liberality of the Saxon Government, and particularly the energetic
support which he received from the enlightened Minister, v. Falken-
stein, enabled him to accomplish for Physiology what had never
before been attempted on an adequate scale. No sooner had he been
appointed, than he set himself to create what was then essential to
the progress of the Science — a great Observatory, arranged not as a
Museum, but much more like a physical and chemical Laboratory,
provided with all that was needed for the apj^lication of exact
methods of research to the investigation of the processes of Life.
The idea which he had ever in view, and which he carried into effect
during the last thirty years of his life with signal success, was to
unite his life-work as an investigator with the highest kind of teach-
ing. Even at Marburg and at Zurich he had begun to form a School ;
for already men nearly of his own age had rallied round him.
Attracted in the first instance by his early discoveries, they were held
by the force of his character, and became permanently associated with
him in his work as his loyal friends and followers — in the highest
sense his scholars. If, therefore, we speak of Ludwig as one of the
greatest teachers of Science the world has seen, we have in mind
his relation to the men who ranged themselves under his leadership
in the building up of the Science of Physiology, without reference to
his function as an ordinary academical teacher.

Of this relation we can best judge by the careful perusal of the
numerous biographical memoirs which have appeared since his death,

* See 'Science Progress,' vol. iv. Nov. 1895.

1896.] on Ludwig and Modern Physiology. 17

more particularly those of Professor His * (Leipzig) ; of Professor
Kronecker f (Bern), who was for many years his coadjutor in the
Institute ; of Professor v. Fick J (Wiirzburg); of Professor v. Kries §
(Freiburg) ; of Professor Mosso || (Turin) ; of Professor Fano %
(Florence) ; of Professor Tigersteclt ** (Upsala) ; of Professor
Stirling,|f in England. With the exception of Fick, whose rela-
tions with Ludwig were of an earlier date, and of his colleague
in the Chair of Anatomy, all of these distinguished teachers were
at one time workers in the Leipzig Institute. All testify their love
and veneration for the master, and each contributes some striking
touches to the picture of his character.

All Lud wig's investigations were carried out with his scholars.
He possessed a wonderful faculty of setting each man to work at
a problem suited to his talent and previous training, and this he
carried into effect by associating him with himself in some research
which he had either in progress or in view. During the early
years of the Leipzig period, all the work done under his direction
was published in the well-known volumes of the ' Arbeiten,' and
subsequently in the ' Archiv ftir Anat, und Physiologic' of du Bois-
Eeymond. Each " Arbeit " of the laboratory appeared in print under
the name of the scholar who co-operated with his master in its produc-
tion, but the scholar's part in the work done varied according to its
nature and his ability. Sometimes, as v. Kries says, he sat on the
window-sill while Ludwig, with the efficient helj) of his laboratory
assistant Salvenmoser, did the whole of the work. In all cases
Ludwig not only formulated the problem, but indicated the course
to be followed in each step of the investigation, calling the worker,
of course, into counsel. In the final working up of the results he
always took a principal part, and often wrote the whole paper. But
whether he did little or much, he handed over the whole credit of
the performance to his coadjutor. This method of publication has
no doubt the disadvantage that it leaves it uncertain what part each
had taken : but it is to be remembered that this drawback is
unavoidable whenever master and scholar work together, and is
outweighted by the many advantages which arise from this mode of
co-operation. The instances in which any uncertainty can exist in

* His, "Karl Ludwig und Karl Thiersch. Akademische Gediichtuissrede,"
Leipzig, 1895.

t Kronecker, " Carl Friedrich Wilhelm Ludwig." ' Berliner kliu.
Wochensch.' 1895, no. 21.

X A. Fick, "Karl Ludwig. Nachruf." ' Biographische Blatter,' Berlin,
vol. 1. pt, 3.

§ V. Kries, " Carl Ludwig." Freiburg i. B. 1895.

II Mosso, " Karl Ludwig." ' Die Nation,' Berlin, nos. 38, 39.

•jf Fano, "Per Carlo Ludwig Commemorazione." ' Clinica Moderna,'
Florence, i. no. 7.

** Tigerstedt, " Karl Ludwig. Denkrede." ' Biographische Blatter,' Berlin,
vol. i. pt. 3.

tt Stirling, loc. cit.

Vol. XV. (No. 90.) c

18 Professor Burdon Sanderson [Jan. 24,

relation to tlie real authorship of the Leipzig work are exceptional.
The well-informed reader does not need to be told that Mosso or
Schmidt, Brunton or Gaskell, Stirling or Wooldridge were the
authors of their papers in a sense very different from that in which
the term could be applied to some others of Ludwig's pupils. On
the whole the plan must be judged of by the results. It was by
working with scholars that Ludwig trained them to work afterwards
by themselves ; and thereby accomplished so much more than other
great teachers have done.

I do not think that any of Ludwig's contemporaries could be com-
pared to him in respect of the wide range of his researches. In a
science distinguished from others by the variety of its aims, he was
equally at home in all branches, and was equally master of all
methods, for he recognised that the most profound biological question
can only be solved by combining anatomical, physical and chemical
inquiries. It was this consideration which led him in j^lanning the
Leipzig Institute to divide it into three parts, experimental (in the
more restricted sense), chemical and histological. Well aware that
it was impossible for a man who is otherwise occupied, to maintain
his familiarity with the technical details of Histology and Physio-
logical Chemistry, he placed these departments under the charge
of younger men capable of keeping them up to the rapidly ad-
vancing standard of the time, his relations with liis coadjutors
being such that he had no difficulty in retaining his hold of the
threads of the investigation to which these special lines of inquiry
were contributory.

It is scarcely necessary to say that as an experimenter Ludwig
was unapproachable. The skill with which he carried out difficult
and complicated operations, the care with which he worked, his
quickness of eye and certainty of hand were qualities which he had
in common with great surgeons. In employing animals for exj)eriment
he strongly objected to rough and ready methods, comparing them
to " firing a pistol into a clock to see how it works." Every
experiment ought, he said, to be carefully planned and meditated on
beforehand, so as to accomplish its scientific purpose and avoid the
infliction of pain. To ensure this he performed all operations
himself, only rarely committing the work to a skilled coadjutor.

His skill in anatomical work was equally remarkable. It had
been acquired in early days, and appeared throughout his life to
have given him very great j^leasure, for Mosso tells how, when
occupying the room adjoining that in which Ludwig was working,
as he usually did, by himself, he heard the outbursts of glee which
accompanied each successful step in some difficult anatomical in-
vestigation.

Let us now examine more fully the part which Ludwig played in
the evolution of ideas as to the nature of vital processes which,
as we have seen, took place in the middle of the present century.

Although, as we shall see afterwards, there were many men who.

1896.] on Ludwig and Modern Physiology. 19

before Ludwig's time, investigated the phenomena of life from
the physical side, it was he and the contemporaries who were
associated with him who first clearly recognised the importance of
the principle that vital phenomena can only he understood hy com-
jparison with their physical counterparts^ and foresaw that in this
principle the future of Physiology was contained as in a nutshell.
Feeling strongly the fruitlessness and unscientific character of the
doctrines which were then current, they were eager to discover
chemical and physical relations in the processes of life. In Ludwig's
intellectual character this eagerness expressed his dominant motive.
Notwithstanding that his own researches had in many instances
proved that there are important functions and processes in the
animal organism which have no physical or chemical analogues, he
never swerved either from the principle or from the method founded
upon it.

Although Ludwig was strongly influenced by the rapid progress
which was being made in scientific discovery at the time that he
entered on his career, he derived little from his immediate pre-
decessors in his own science. He is sometimes placed among the
pupils of the great comparative Anatomist and Physiologist, J. Miiller.
This, however, is a manifest mistake, for Ludwig did not visit Berlin
until 1847, when Miiller was nearly at the end of his career. At
that time he had already published researches of the highest value
(those on the Mechanism of the Circulation and on the Physiology of
the Kidney), and had set forth the line in w^hich he intended to direct
his investigations. The only earlier Physiologist with whose work
that of Ludwig can be said to be in real continuity was E. H. Weber,
whom he succeeded at Leipzig, and strikingly resembled in his way
of working. For Weber, Ludwig expressed his veneration more
unreservedly than for any other man excepting perhaps Helmholtz,
regarding his researches as the foundation ou which he himself
desired to build. Of his colleagues at Marburg he was indebted in
the first place to the anatomist. Professor Ludwig Fick, in whose
department he began his career as Prosector, and to whom he owed
facilities without which he could not have carried out his earlier
researches; and in an even higher degree to the great Chemist,
R. W. Bunsen, from whom he derived that training in the exact
sciences which was to be of such inestimable value to him after-
wards.

There is reason, however, to believe, that, as so often happens,
Ludwig's scientific progress was much more influenced by his con-
temporaries than by his seniors. In 1847, as we learn on the one
hand from du Bois-Reymond, on the other from Ludwig himself, he
visited Berlin for the first time. This visit was an important one
both for himself and for the future of Science, for he there met
three men of his own age, Helmholtz, du Bois-Reymond and Briicke,
who were destined to become his life-friends, all of whom attained
to the highest distinction, and one of whom is still living. They

c 2

20 Professor Burdon Sanderson [Jan. 24,

all were full of tlie same enthusiasm. As Ludwig said when
speaking of this visit : " We four imagined that we should constitute
Physiology on a chemico-physic foundation, and give it equal scientific
rank with Physics ; but the task turned out to be much more difficult
than we anticipated." These three young men, who were devoted
disciples of the great Anatomist, had the advantage over their
master in the better insight which their training had given them
into the fundamental principles of scientific research. They had
already gathered around themselves a so-called " physical " school of
Physiology, and welcomed Ludwig on his arrival from Marburg as
one who had of his own initiative, undertaken in his own Univer-
sity das BefreiungswerJc aus dem Vitalismus.

The determination to refer all vital phenomena to their physical
or chemical CDunterparts or analogues, which, as I have said, was
the dominant motive in Lud wig's character, was combined with
another quality of mind which, if not equally influential, was even
more obviously displayed in his mode of thinking and working. His
first aim, even before he sought for any explanation of a structure
or of a process, was to possess himself, by all means of observation
at his disposal, of a complete objective conception of all its relations.
He regarded the faculty of vivid sensual realisation (lehendige
sinnliche Anschauung) as of special value to the investigator of
natural phenomena, and did his best to cultivate it in those who
worked with him in the laboratory. In himself, this objective
tendency (if I may be permitted the use of a word which, if not
correct, seems to express what I mean) might be regarded as almost
a defect, for it made him indisposed to appreciate any sort of
knowledge which deals with the abstract. He had a disinclination
to philosophical speculation which almost amounted to aversion, and,
perhaps for a similar reason, avoided the use of mathematical
methods even in the discussion of scientific questions which ad-
mitted of being treated mathematically — contrasting in this respect
with his friend du Bois-Reymond, resembling Brticke. But as a
teacher the quaMty was of immense use to him. His power of vivid
realisation was the substratum of that many-sidedness which made
him, irrespectively of his scientific attainments, so attractive a
personality.

I am not sure that it can be generally stated that a keen scientific
observer is able to appreciate the artistic aspects of Nature. In
Ludwig's case, however, there is reason to think that the aesthetic
faculty was as developed as the power of scientific insight. He
was a skilful draughtsman, but not a musician ; both arts were
however a source of enjoyment to him. He was a regular frequenter
of the Gewandhaus concerts, and it was his greatest pleasure to bring
together gifted musicians in his house, where he played the part of
an intelligent and appreciative listener. Of painting he knew more
than of music, and was a connoisseur whose opinion carried weight.
It is related that he was so worried by what he considered bad art,

1896.] on Ludivig and Modern Physiology. 21

that after the redecoration of the Gewandhaus concert-room, he was
for some time deprived of his accustomed pleasure in listening to
music.

Ludwig's social characteristics can only be touched on here in so
far as they serve to make intelligible his wonderful influence as a
teacher. Many of his pupils at Leipzig have referred to the schone
Gemeinsamheit which characterised the life there. The harmonious
relation which, as a rule, subsisted between men of different education
and different nationalities, could not have been maintained had not
Ludwig possessed side by side with that inflexible earnestness which
he showed in all matters of work or duty, a certain yoiithfulness of
disposition which made it possible for men much younger than
himself to accept hig friendship. This sympathetic geniality was,
however, not the only or chief reason why Ludwig's pupils were the
better for having known him. There were not a few of them who for
the first time in their lives came into personal relation with a man
who was utterly free from selfish aims and vain ambitions, who was
scrupulously conscientious in all that he said and did, who was what
he seemed, and seemed what he was, and who had no other aim than
the advancement of his science, and in that advancement saw no
other end than the increase of human happiness. These qualities
displayed themselves in Ludwig's daily active life in the laboratory,
where he was to be found whenever work of special interest was
going on ; but still more when, as happened on Sunday mornings, he
was "at home "in the library of the Institute — the corner room in
which he ordinarily worked. Many of his " scholars " have put on
record their recollections of these occasions ; the cordiality of the
master's welcome, the wide range and varied interest of his conversa-
tion, and the ready appreciation with which he seized on anything that
was new or original in the suggestions of those present. Few men
live as he did, " im Ganzen, Guten, Sclwnen,'' and of those still fewer
know how to communicate out of their fulness to others.

Tlie Old and the New Vitalism,

Since the middle of the century the progress of Physiology has
been continuous. Each year has had its record, and has brought
with it new accessions to knowledge. In one respect the rate of
progress was more rapid at first than it is now, for in an unexplored
country discovery is relatively easy. In another sense it was slower,
for there are now scores of investigators for every one that could be
counted in 1840 or 1850. Until recently there has been throughout
this period no tendency to revert to the old methods — no new
departure — no divergence from the principles which Ludwig did so
much to enforce and exemplify.

The wonderful revolution which the appearance of the ' Origin of
Species ' produced in the other branch of Biology, promoted the

22 Professor Burdon Sanderson [Jan, 24,

progress of Physiology by the new interest which it gave to the study,
not only of structure and development, but of all other vital
phenomena. It did not, however, in any sensible degree affect our
method or alter the direction in which Physiologists had been working
for two decades. Its most obvious effect was to sever the two subjects
from each other. To the Darwinian epoch comparative Anatomy
and Physiology were united, but as the new Ontology grew it became
evident that each had its own problems and its own methods of
dealing with them.

The old vitalism of the first half of the century is easily
explained. It was generally believed that, on the whole, things
v/ent on in the living body as they do outside of it ; but when a
difSculty arose in so explaining them the Physiologist was ready at
once to call in the aid of a " vital forced It must not, however, be
forgotten that, as I have already indicated, there were great teachers
(such, for example, as Sharpey and Allen Thomson in England,
Magendie in France, Weber in Germany) who discarded all vitalistic
theories, and concerned themselves only with the study of the time-
and place-relations of phenomena ; men who were before their time
in insight, and were only hindered in their application of chemical
and physical principles to the interpretation of the processes of life
by the circumstance that chemical and physical knowledge was in
itself too little advanced. Comparison was impossible, for the
standards were not forthcoming.

Vitalism in its original form gave way to the rapid advance of
knowledge as to the correlation of the physical sciences, which took
place in the forties. Of the many writers and thinkers who
contributed to that result, J. R. Mayer and Helmholtz did so most
directly, for the contribution of the former to the establishment of
the Doctrine of the Conservation of Energy had physiological
considerations for its point of departure ; and Helmholtz, at the time
he wrote the " Erlialtung der Kraft," was still a Physiologist.
Consequently when Ludwig's celebrated Lehrhuch came out in
1852, — the book which gave the coup de grace to vitalism in the old
sense of the word, — his method of setting forth the relations of vital
phenomena by comparison with their physical or chemical counter-
parts, and his assertion that it was the tasv of Physiology to make
out their necessary dependence on elementary conditions, although in
violent contrast with current doctrine, were in no way surprising
to those who were acquainted with the then recent progress of
research. Lud wig's teaching was indeed no more than a general
application of principles which had already been applied in par-
ticular instances.

The proof of the non-existence of a special " vital force " lies in
the demonstration of the adequacy of the known sources of energy in
the organism to account for the actual day by day expenditure of
heat and work — in other words, on the possibility of setting forth an
energy balance sheet, in which the quantity of food which enters the

1896.] on Ludwig and Modern Physiology. 23

body in a given period (hour or day) is balanced by an exactly
corresponding amount of heat produced or external work done. It is
interesting to remember that the work necessary for preparing such a
balance sheet (which Mayer had attempted but, from want of suffi-
cient data, failed in) was begun thirty years ago in the laboratory of
the Royal Institution by the present Foreign Secretary of the
Royal Society. But the determinations made by Dr. Frankland
related to one side of the balance sheet, that of income. By his
researches in 1866 he gave Physiologists for the first time reliable
information as to the heat value (i.e. the amount of heat yielded by
the combustion) of different constituents of food. It still remained
to apply methods of exact measurement to the expenditure side of the
account. Helmholtz had estimated this, as regards man, as best he
might ; but the technical difficulties of measuring the expenditure
of heat of the animal body appeared until lately to be almost
insuperable. Now that it has been at last successfully accomplished,
we have, the experimental proof that in the process of life there is no
production or disappearance of energy. It may be said that it was
unnecessary to prove what no scientifically sane man doubted.
There are, however, reasons why it is of importance to have
objective evidence that food is the sole and adequate source of the
energy which we day by day or hour by hour disengage, whether in
the form of heat or external work.

In the opening i)aragraph of this section it was observed that
until recently there had been no tendency to revive the vitalistic notion
of two generations ago. In introducing the words in italics I
referred to the existence at the present time in Germany of a sort of
reaction, which under the term " Neovitalismus " has attracted some
attention — so much indeed that at the Versammlung Deutscher
Natur for seller at Liibeck last September, it was the subject of one of
the general addresses. The author of this address (Prof. Rindfleisch)
was, I believe, the inventor of the word, but the origin of the
movement is usually traced to a work on Physiological Chemistry
which an excellent translation by the late Dr. Wooldridge has made
familiar to English students. The author of this work owes it to
the language he employs in the introduction on " Mechanism and
Vitalism," if his position has been misunderstood, for in that
introduction he distinctly ranges himself on the vitalistic side. As,
however, his vitalism is of such a kind as not to influence his method
of dealing with actual problems, it is only in so far of consequence
as it may affect the reader. For my own part I feel grateful to
Professor Bunge for having produced an interesting and readable
book on a dry subject, even though that interest may be 23artly due
to the introduction into the discussion, of a question wliich, as he
presents it, is more speculative than scientific.

As regards other physiological writers to whom vitalistic tenden-
cies have been attributed, it is to be observed that none of them have
even suggested that the doctrine of a " vital force " in its old sense

24 Professor Burdon Sanderson [Jan. 24,

should Le revived. Their contention amounts to little more than this,
that in certain recent instances improved methods of research appear
to have shown that processes, at first regarded as entirely physical or
chemical, do not conform so precisely as tbey were expected to do to
chemical and physical laws. As these instances are all essentially
analogous, reference to one will serve to explain the bearing of the
rest.

Those who have any acquaintance with the structure of the animal
body will know that there exists in the higher animals, in addition to
the system of veins by which the blood is brought back from all parts
to the heart, another less considerable system of branched tubes, the
lymphatics, by which, if one may so express it, the leakage of the
blood-vessels is collected. Now, without inquiring into the why of
this system, Ludwig and his puj)ils made and continued for many
years elaborate investigations which were for long the chief sources
of our knowledge, their general result being that the efficient cause of
the movement of the lymph, like that of the blood, was mechanical.
At the Berlin Congress in 1890 new observations by Professor Hei-
denhain of Breslau made it appear that under certain conditions the
process of lymph formation does not go on in strict accordance with
the physical laws by which leakage through membranes is regulated ;
the experimental results being of so unequivocal a kind that, even
had they not been confirmed, they must have been received without
hesitation. How is such a case as this to be met ? The " Neovi-
talists " answer promptly by reminding us that there are cells, i.e.
living individuals, placed at the inlets of the system of drainage with-
out which it would not work, that these let in less or more liquid
according to circumstances, and that in doing so they act in obedience,
not to physical laws, but to vital ones — to laws which are special to
themselves.

Now, it is perfectly true that living cells, like working bees, are
both the architects of the hive and the sources of its activity ; but if
we ask how honey is made, it is no answer to say that the bees make
it. We do not require to be told that cells have to do with the
making of lymph, as with every process in the animal organism ; but
what we want to know is how they work, and to this we shall never
get an answer so long as we content ourselves with merely ex-
plaining one unknown thing by another. The action of cells must
be explained, if at all, by the same method of comparison with
physical or chemical analogues that we employ in the investigation of
organs.

Since 1890 the problem of lymph formation has been attacked by
a number of able workers — among others in London, by Dr. Starling
of Guy's Hospital, who, by sedulously studying the conditions under
which the discrepancies between the actual and the expected have
arisen, has succeeded in untying several knots. In reference to the
whole subject, it is to be noticed that the process by which difficul-
ties are brought into view is the same as that by which they arc

1896.] on Ludwig and Modern Physiology. 25

eliminated. It is one and the same method throughout, by which,
step by step, knowledge perfects itself — at one time by discovering
errors, at another by correcting them ; and if at certain stages in this
progress difficulties seem insuperable, we can gain nothing by calling
in, even provisionally, the aid of any sort of Eidolon, whether " cell,"
" protoplasm," or internal principle.

It thus appears to be doubtful whether any of the biological
writers wLo have recently professed vitalistic tendencies are in reality
vitalists. The only exception that I know is to be found in the
writings of a well-known worker, Hans Driesch,* who has been led by
his researches on what is now called the Mechanics of Evolution, to
revert to the fundamental conception of vitalism, that the laws which
govern vital processes are not physical, but biological— that is, pecu-
liar to the living organism, and limited thereto in their operation.
Driesch's researches as to the modifications which can be produced by
mechanical interference in the early stages of the process of onto-
genesis have enforced upon him considerations which he evidently
regards as new, though they are familiar enough to Physiologists.
He recognises that although by the observation of the successive
stages in the ontogenetic process, one may arrive at a perfect know-
ledge of the relation of these stages to each other, this leaves the
efficient causes of the development unexplained (fiiJirt nicht zu einem
Erhenntniss ilirer hewirkenden Ursachen) — it does not teach us why one
form springs out of another. This brings him at once face to face
with a momentous question. He has to encounter three possibilities —
he may either join the camp of the biological agnostics and say with
du Bois-Eeymond, not only " ignoramus " but " ignorahimits " ; or be
content to work on in the hope that the physical laws that underlie
and explain organic Evolution may sooner or later be discovered ; or
he may seek for some hitherto hidden Law of Organism, of which the
known facts of Ontogenesis are the expression, and which, if accepted
as a Law of Nature, would explain everything. Of the three alterna-
tives Driesch prefers the last, which is equivalent to declaring himself
an out-and-out vitalist. He trusts by means of his experimental
investigations of the Mechanics of Evolution to arrive at " elementary
conceptions " on which by " mathematical deduction " | a complete
theory of Evolution may be founded.

If this anticipation could be realised, if we could mentally
construct with the aid of these new Principia the ontogeny of a single
living being, the question whether such a result was or was not incon-

* Driesch, ' Entwicklungsmeclianische Studieu ' : a Series of ten Papers, of
whicli the first six have appeared in the ' Zeitsch. f. w. Zoologie,' vols. liii. and
Iv. the rest in the ' Mittheilungen ' of the Naples Station.

t " Elementarvorstellungen .... die zwar mathematische Deduktion aller
Erscheinungen aus sich gestatten mdchten." Driesch, " Beitrage ziir theore-
tischen Morphologic." ' Biol. Centralblatt,' vol. xii. p. 539, 1892.

26 Prof. B. Sanderson on Ludwig and Modern Physiology. [Jan. 24,

sistent with the uniformity of Nature, would sink into insignificance
as compared with the splendour of such a discovery.

But will such a discovery ever be made ? It seems to me even
more improbable than that of a physical theory of organic evolution.
In the meantime it is satisfactory to reflect that the opinion we may
be led to entertain on this theoretical question need not affect our
estimate of the value of Driesch's fruitful experimental researches.

[J. B. S.]

1896.] National Biography. 27

WEEKLY EVENING MEETING,

Friday, January 31, 1896.

Sir Benjamin Baker, K.C.M.G. LL.D. F.E.S. Ma
in the Chair.

Sidney Lee, Esq. the Editor of the ' Dictionary of National
Biography.'

National Biograjphj.
(Abstract.)

Mr. Sidney Lee pointed out that pride in the achievement of one's
ancestors is almost as widely distributed a characteristic of mankind
as the power of speech. In China, the national religion centres round
a worship of progenitors to very remote degrees, and Western nations
exhibit the same instinctive desire to do honour to the memories of
those who, by character and exploits, have distinguished themselves
from the mass of their countrymen. But no memorial can be national
and efficient, unless it be at once permanent, public and perspicuous.
It should take such a shape as to leave no doubt in the mind of
posterity what was the nature of the achievement or characteristics
that generated in the nation the desire of commemoration. Monu-
ments in stone or brass preserve bare names, and are not lasting.
" The safest way," wrote Thomas Fuller, " to secure a memory from
oblivion is by committing the same to writing.'' The rarity of poetic
memorials like Shelley's ' Adonais ' or ' The Burial of Sir John
Moore,' which are at once permanent, public and perspicuous, compels
recourse to the more adaptable machinery of biograjjhy. But
biography, as it is ordinarily practised, works fitfully and capriciously.
If biography is to respond to a whole nation's commemorative aspira-
tions, its bounds must be enlarged and defined, so as to admit with
unerring precision every one who has excited the nation's commemora-
tive instinct, while the mode of treatment must be so contrived, so
contracted, that the collected results may not overwhelm us by their
bulk. Biography working with these aims and on these lines may
justly be called national biography. Carlyle's definition of the
function of history — " to find out great men, clean the dirt from them
and place them on their proper pedestals " — more properly defines
the function of national biography. The aims of the historian and
biographer are quite distinct. The historian deals with aggregate
movements of men, with political events and institutions, with the
evolution of society ; he looks at mankind through a field-glass ; his

28 3Ir. Sidney Lee [Jan. 31,

purpose is often served if lie catch a glimpse, or no glimpse at all, of
personages who command the biographer's most earnest attention.
The historian barely mentions men like Dr. Johnson, Benvenuto
Cellini, Lord Herbert of Cherbury, or Samuel Pepys. The
biographer, on the other hand, puts individual men under a magni-
fying glass and submits them to minute examination ; professionally
he cares little or nothing for the evolution of society. But while
the historian and biographer seek different goals, they can render
one another very genuine service on the road. The biogra^iher
requires an intelligent knowledge of the historical environment, if he
would portray in fitting perspective all the operations of his unit :
but his art is to sternly subordinate his scenery to his actors, and
never to crowd his stage with upholstery and scenic apparatus that
can only distract the spectators' attention from the proper interest of
tlie piece. The historian's debt to the biographer is even greater
than the biographer's to the historian. The biographer has to
explore many a dismal swamp in which the historian is not called
upon to set foot. Parish registers, academic archives, family letters,
uuprinted memoranda, county histories, genealogical dissertations
and pedigrees, are leading features of the country in which the bio-
grapher passes his days. But such material may secrete an impor-
tant historical fact, or throw a welcome light on an obscure step in an
historic movement. IMacaulay made frequent appeals to biography with
excellent effect, but Mr. Froude neglected it. His picture of Queen
Mary of England, as a hag-like bigot, might easily have been rectified
by an occasional resort to pedestrian biographical sources. Nor will
the lack of accessible biography long constitute a sufficient excuse for
the historian's neglect of biographic sources. The historian will soon
have at his command a completed register of national biography.

The Method of National Biograj^hj. — National biography seeks, as
Priestley said of science, " to comprise as much knowledge as possible
in the smallest compass." Conciseness carried to the furthest limits
consistent with the due performance of his commemorative function,
is the first law of the national biographer's being. No place can be
accorded to rhetoric, voluble enthusiasm, emotion, or loquacious senti-
ment. The writings of authors, the works of painters or engravers,
must be cast into the unexhilarating form of chronological series
or catalogues, and the result must be rather like a map or plan
than a picture. The result need not necessarily be devoid of
literary art, and should give the reader the feeling — one as pleasing
as any that art can give — that to him has been imparted all the
information for which his commemorative instinct craves. The
national biographer must nerve himself to omit much detail, much
anecdote that may find a lawful place in individual biography.
It is solely in the few careers which exhibit unusual spiritual
tendencies or conspicuous deflections from the ordinary standard of
morality, that any reference to a man's moral or spiritual experience
is justifiable. Such lapses as the marital adventures of Byron,

1896.] on National Biography. 29

Nelson or Parnell, Coleridge's indulgence in opium, Person's indul-
gence in drink, which vitally affected their careers, must be frankly
but judiciously and briefly described. Here, as at every point in his
work, the national biograj)her has to cultivate the judicial temper, for
he has not merely to record reputations but to adjust them. He
must not exalt Cromwell at Charles I.'s expense, nor Charles I. at
Cromwell's. Careers embittered by controversy must be treated with
due regard to all the interests involved. Many of these methods of
national biography might be adopted without disadvantage by the
individual biographer, who is often no expert in the biographic art ;
no limit is set to his diffuseness, to his indulgence in trivial details, to
his partisan tendencies ; with the result that the hero's really eminent
achievements and distinctive characteristics lie buried under the
dust and ashes of special pleading, commonplace gossip or helpless
eulogy. The national biographer aims at commemorating all who
have excited the commemorative instinct in any appreciable degree in
any dej^artment of national life ; but it is difficult to enunciate any
principle of exclusion that shall carry universal conviction. An
Aristotelian definition may apply ; and it may be suggested that
no man's life should be admitted that does not present at least one
action that is " serious, complete and of a certain magnitude." Official
dignities, except of the rarest and most dignified kind, give in them-
selves no claim to national commemoration. But national biography
must satisfy the commemorative instinct of all sections of the
population, and include representatives of varied political or religious
movements. The national biographer must, at times, too, correct
the working of the nation's commemorative instinct, by noticing
those who, having prepared the way for great inventions, have
been forgotten, while all the glory has gone to those who have reaped
the benefit of preceding efforts. It is obvious that of the aggregate
mass of mankind very few are taken. The lecturer's personal experi-
ence led him to estimate that from the year 1000 a. d. to the end of
the present century, 30,000 persons have achieved in this Kingdom
such measure of distinction as to claim the national biographer's
attention ; i.e. 1 in 5000 of the adult population. Up to the
end of the seventeenth century the ratio for adults seems to have
been 1 in 6250. Last century it rose almost impercej)tibly, viz. to
1 in 6000. In this century, when we include the English speaking
inhabitants of our colonies, but exclude the United States, the
ratio sensibly rises, viz. to one in 4000, and at the present moment
600 adults in the County of London are qualifying for admission to
a complete register of national biography, of whom twenty should be
women. The increase of the ratio of distinction in the present
century is largely due to the multiplication of intellectual callings,
the specialisation of science and art, and the improvement of educational
machinery.

Ex'periments in 'National BiograjjJiy. — In conclusion the lecturer
briefly described the efforts previously made in this country in

30 Mr. Sidney Lee [Jan. 31,

the direction of national biography. After alluding to mediaeval
collections of lives of saints, popes, kings and others, he reviewed
the development of biography during the sixteenth and seventeenth
centuries, beginning with Leland, Bale, Pits and Foxe. These
collective biographers were religious partisans whose theological
prejudices had to be counteracted before national biography could
enjoy an adequate measure of imj)artiality. Later on, biographers
like the Scotsmen Dempster and Mackenzie, betrayed an excessive
patriotism or racial bias which overruled all other considerations
with equally disastrous results. A great advance was seen
during the seventeenth century in Naunton's ' Fragmenta Eegalia,'
Holland's ' Heroologia,' Aubrey's ' Lives,' but above all in Wood's
' Athenae Oxonienses ' and Fuller's ' Worthies of England.' In the
eighteenth century the encyclopaedic movement gave rise to a genuine
attempt at national biography in the work called ' Biographia
Britannica.' The first volume appeared in 1747, the seventh and
last in 1763. The scheme had grave defects, but they should be
treated with the merciful consideration to which the shortcomings
of all pioneers are entitled. Moreover, unlike some of its suc-
cessors, the ' Biographia Britannica ' achieved the distinction of
reaching the letter Z. Eleven years later Dr. Johnson was invited
to prepare a second edition. But Dr. Johnson had had one
experience in dictionary making and he not unnaturally declined to
have a second. The task was undertaken by another (Dr. Kippis),
and in 1793 there appeared the fifth and last volume of the second
edition of the ' Biographia Britannica.' But though the work had
reached its last volume, its final pages had only arrived at the
beginning of the letter F. At the article on Sir Thomas Fastolf
this undertaking stopped, to remain for ever a magnificent fragment,
a melancholy wreck, a fearful example.

" Checks and disasters
Grow in the veins of actions highest reared."

Some twenty-one years later, Alexander Chalmers completed in
thirty-two volumes his very respectable ' Biographical Dictionary.'
Some thirty years later, the Society for the Diffusion of Useful
Knowledge, under a committee, of which Lord Brougham was chair-
man, and Lord Spencer (father of the present earl) was vice-chairman,
designed a dictionary of biography which was to combine national
with universal biography, on an ambitious scale. But the letter A
was only c(mi]3leted in seven volumes, and it is, therefore, not
surprising to learn that that venture went no further. A very
modest attempt in the same direction followed, in Rose's ' Biographical
Dictionary,' but here the first three letters of the aljDhabet absorbed
six volumes, and the remaining twenty-three letters were compressed
into another six. There followed a pause in the efforts of collective
biography in this country. After the middle of the century, Germany

1896.] on National Biography, 31

Austria and Belgium each set on foot a register of national biography
under the auspices of state-aided literary academies. At length, a
new and very strenuous endeavour was made to supply the defect in
our own literature, made under the auspices of no state-aided literary
academies, but by the independent and enlightened exertion of one
great English publisher. In conclusion the lecturer said : " It does
not become me to say much of this last endeavour, with which I
am very closely identitied. The ' Dictionary of National Biography,'
which was begun some thirteen years ago under Mr. Leslie Stephen's
editorship, is now nearing completion under my awn. Even if the
* Dictionary of National Biography' does not practise at all points
those counsels of perfection which I have addressed to you to-night,
if it contains errors from which no work of such multiplicity was ever
free ; yet those who are acquainted with it will admit that it has
accomplished much, that the writers who have co-operated in its
production have vastly improved upon their predecessors, and finally
that it is none the less efficient, and none the less worthy of its
mighty theme, because, while it seeks to do the State some service, it
is the outcome of private enterprise, and the handiwork of private
citizens."

32 General Monthly Meeting. [Feb. 3,

GENERAL MONTHLY MEETING,

Monday, February 3, 1896.

Sir James Cbichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Mrs. Montagu,

Robert R. Tatlock, Esq. F.C.S. F.I.C.

Ernest Westlake, Esq.

were elected Members of the Royal Institution.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

The Governor- General of India — Geological Survey of India: Kecords. Vol.

XXVIIL Part 4. 8vo. 1895.
The Lords of the Adyniralty—^iiutical Ahiianac for 1899. 8vo.
The Minister of Public Instruction, Paris — Documents inedits sur I'liistoire de
France :
Lettres de Catherine de Medicis publics par M. le Ct. H. de la Ferriere.

Tome V. 1574-77. 4to. 1895.
Lett]-es de Cardinal Mazarin public's par M. le Vte. d'Avenel. Tome VIII.
1657-58. 4to. 1894.
The MeteoroJoqical Office — Meteorological Observations at Stations of tlic Second
Order for 1891.' 4to. 1895.
Hourly Means for 1891. 4to. 1895.
Accademia dei Lincei, Reale, Roma — Atti, Serie Quinta : Rendiconti. Classe di
Scienze Morali, etc. Vol. IV. Fasc. 9, 10°. 8vo. 1895.
Classe di Scienze Fisiche, etc. 2^^ Semestre, Vol. IV. Fasc. 9-12 ; Vol. V.
Fasc. 1. 8vo. 1895.
Agricultural Society of England, i?o?/aZ— Journal, Vol. VI. Part 4. 8vo. 1895.
American Academy of Arts and Sciences — Proceedings, Vol. XXX. 8vo. 1895.
Aristotelian Society— Proceedings, Vol. III. No. 1. 8vo. 1895.
Asiatic Society of Bengal— Proceedings, 1895, Nos. 7, 8. Svo.

Journal, Vol. LXIV. Part 1, No. 2. Svo. 1895.
Asiatic Society of Great Britain, Boyal — Journal for Jan. 1896. Svo.
Astronomical Society, Boyal — Memoirs, Vol. LI. 1892-95. Svo.

Monthly Notices, Vol. LVI. Nos. 1, 2. Svo. 1895.
Bandsept, A. Esq. (the Author)— Br alenrs auto-melangeurs-atomiseurs pour com-
bustions intensives. Svo. 1894-95.
Bankers, Institute o/— Jonrnal, Vol. XVI. Part 9 ; Vol. XVII. Part 1. Svo. 1895.
Bimetallic Lgagjte— Replies to the Leaflets of the Gold Standard Defence Asso-
ciation, and other papers. Svo. 1895.
Bimetallist for 1895. Svo.
Boston Public Library, C7.>S'.^.— Bulletin for July-Oct. 1895. Svo.
Boston Society of Natural History— Proceedings, Vol. XXVI. Part 4. Svo. 1895.
Memoirs, Vol. V. Nos. 1, 2. 4to. 1895.

1896.] General Monthly Meeting. 33

Botanic Society, Royal — Quarterly Record, No. G3. 8vo. 1895.

British Architects, Boyal Institute of — Journal, 1895-96, Nos. 3-5.

British Association for the Advancement of Science — Report of the Sixty-fifth

Meeting of the British Association held at Ipswich, 1895. 8vo. 1895.
British Astronomical Association — -Journal, Vol. V. No. 11; Vol. VI. Nos. 2, 3.

8vo. 1895.
Camera Club — Journal for Dec. 1895 and Jan. 1896. 8vo.
Chelsea Puhlic Libraries —Gla.ssi&ed Catalogue of Books upon Science, the Useful

Arts and the Fine Arts. 8vo. 1895.
Chemical Industry, Society o/— Journal, Vol. XIV. Nos. 11, 12. 8vo. 1895.
Chemical Society— J ournsd for Dec. Supplementary No. 1895 and Jan. 1896. 8vo.

Proceedings, Nos. 156, 157. 8vo. 1895.
CJiicago, Field Columbian Museum — Publications, Nos. 2-4. 1895.
Church, Professor A. H. F.R.S. M.R.I. — Reports of a Sub-Committee of the
Burlington Fine Arts Club appointed to test certain methods devised for the
Preservation of Drawings in Water Colour. 8vo. 1895.
Cracovie, V Academic des Sciences — Bulletin, 1895, Nos. 8, 9. 8vo.
Dawson, George, Esq. (the Author) — Glacial Deposits of South Western Alberta

in the vicinity of the Rocky Mountains. 8vo. 1895.
Dax, Societe de Borda — Bulletin, 1895, Deuxieme et Quatrieme Trimestre. 8vo.

1895.
Donat, Herr Karl vow— The Pontine Marshes. By F. M. von Donat. 8vo. 1895.
East India Association — Journal, January 1896. 8vo.
Editors — American Journal of Science for Dec. 1895 and Jan. 1896. 8vo.

Analyst for Dec. 1895 and Jan. 1896. 8vo.

Anthony's Photographic Bulletin for Dec. 1895 and Jan. 1896. 8vo.

Astrophysical Journal for Dec. 1895 and Jan. 1896. 8vo.

AtheuiBum for Dec. 1895 and Jan. 1896. 4to.

Author for Dec. 1895 and Jan. 1896.

Brewers' Journal for Dec. 1895 and Jan. 1896. 8vo.

Chemical News for Dec. 1895 and Jan. 1896. 4to.

Chemist and Druggist for Dec. 1895 and Jan. 1896. 8vo.

Electrical Engineer for Dec. 1895 and Jan. 1896. fol.

Electrical Engineering for Dec. 1895 and Jan. 1896.

Electrical Review for Dec. 1895 and Jan. 1896. 8vo.

Electric Plant for Dec. 1895 and Jan. 1896. 8vo.

Engineer for Dec. 1895 and Jan. 1896. fol.

Engineering for Dec. 1895 and Jan. 1896. fol.

Homoeopathic Review, Dec. 1895 and Jan. 1896.

Horological Journal for Dec. 1895 and Jan. 1896. 8vo.
; Industries and Iron for Dec. 1895 and Jan. 1896. fol.

Invention for Dec. 1895 and Jan. 1896. 8vo.

Law Journal for Dec. 1895 and Jan. 1896. 8vo.

Machinery Market for Dec. 1895 and Jan. 1896. 8vo.

Monist for Jan. 1896. 8vo.

Nature for Dec. 1895 and Jan. 1896. 4to.

Nuovo Cimento for Dec. 1895 and Jan. 1896. 8vo.

Photographic Work for Dec. 1895 and Jan. 1896. 8vo.

Physical Review, Vol. III. No. 4. 8vo. 1896.

Science Siftings for Dec. 1895 and Jan. 1896. 8vo.

Scots Magazine for Dec. 1895 and Jan. 1896. 8vo.

Technical World for Dec. 1895 and Jan. 1896. 8vo.

Transport for Dec. 1S95 and Jan. 1896. fol.

Tropical Agriculturist for Dec. 1895 and Jan. 1896. 8vo.

Work for Dec. 1895 and Jan. 1896. 8vo.

Zoophilist for Dec. 1895 and Jan. 1896. 4to.
Elgood, Rev. J. C. (the Author) — Readings in Horace. 8vo. 1895.
Engineering Review (the Editor) — Engineering Review, Vol. I. Nos. 1-6, 8-10;
Vol. II. Nos. 3, 9; Vol. III. Nos. 1-5. 8vo. 1893-95.
Vol. XV. (No. 90.) d

34 General Monthly Meeting. [Feb. 3,

Florence Biblioteea Nazionale Centrale—BoW&imo, Nos. 238-241. 8vo. 1895.

Franklin Institute— J ournsA, Nos. 840, 841. 8vo. 1895.

Geographical Society, Eoijal — Geographical Journal for Dec. 1895 and Jan. 1896.

,8vo.
Borticultural Society, Eot/aZ— Eeport of Council for 1895-96. 8vo.

Arrangements for 1896. 8vo.
Imperial Institute — Imperial Institute Journal for Dec. 1895 and Jan. 1896.
Iron and Steel Institute— J oumsd, Vol. XL VIII. 1895, No. 2. Svo.
Johns Eophins University — University Studies: Thirteenth Series, Nos, 11, 12.
Svo. 1895.
American Chemical Journal, Vol. XVII. No. 10 ; Vol. XVIII. No. 1. 8vo.

1895.
American Journal of Philology, Vol. XVI. No. 3. Svo. 1895.
University Circular, No. 122. 4to. 1895.
Linnean Society — Journal, No. 214. Svo. 1895.

London County Council Technical Education Board — London Technical Educa-
tion Gazette for Dec. 1895 and Jan. 1896. Svo. 1895.
Manchester Geological Society — Transactions, Vol. XXIV. Part 1. Svo. 1895.
Meteorological Society, Boyal — Quarterly Journal, No. 96. Svo. 1895.

Meteorological Eecord, Nos. 57, 58. Svo. 1895.
Middlesex Hospital— Bepovts for 1894. Svo. 1895.
Munich, Bavarian Academy of Sciences, Boyal — Sitzungsberichte, 1892, Heft 3 ;

1SJ3, Heft 1. Svo. 1893.
New York Academy of Sciences — Transactions, Vol. XIV. Svo. 1894-95.
Neiv Zealand, the Agent- General for — Fioi-d-land (New Zealand). By G. M. Ross.

fol. 1895.
New Zealand, Begistrar-Generalfor—The New Zealand OflScial Year- Book, 1895.

Svo. 1895.
Norman, J. H. Esq. (the Author)— The World's Two Metal and Four other

Currency Intermediates. Svo. 1895.
Nova Scotian Institute of Science— Froceediugs and Transactions, Vol. VIII.

Part 4. Svo. 1895.
Odontological Society of Great Britain — Transactions, Vol. XXVIII. No. 2. Svo.

1895.
Onnes, Professor H. Kamerlingh — Communication from the Laboratory of

Physics at the University of Leiden, Nos. 6, 16, 18, 22. Svo. 1893-95.
Payne, W. W. (the Editor) — Astronomy and Astro-Physics for Feb.-March, 1894.

Svo.
Pascoe, C. E. Esq. (the Editor)— London of To-Day's Calendar for Dec. 1895.

Svo.
Pharmaceutical Journal (the Editor) — The Discovery of Oxygen. Svo. 1895.

(Pharmaceutical Journal Reprint.)
Pharmaceutical Society of Great Britain — Calendar for 1896. Svo.

Journal for Dec. 1895 and Jan. 1896. Svo.
Philadelphia, Academy of Ncdural Sciences — Proceedings, 1895, Part 2. Svo.
Photogra'phic Society, Boyal — The Photographic Journal, Nov. Svo. 1895.
Physical Society of io;idon— Proceedings, Vol. XIII. Part 13 ; Vol. XIV. Part 1.

Svo. 1895-96.
Bichter, Prof. Max. Chnefalsch, Ph.D. — Grseco-Phcenician Architecture in Cyprus,
with special reference to the origin and development of the Ionic Volute,
1895.
Bochechouart, Sodete des Amis des Sciences et Arts de — Bulletin, Tome V. Nos. 1, 2.

Svo. 1895.
Bochester Academy of Science — Proceedings, Vol. II. Parts 3, 4. Svo. 1894-95-
Borne, Ministry of Public Works — Giornale del Genio Civile, 1895, Fasc. 8°-ll°.

And Designi. fol.
Boyal Irish Academy — Proceedings, Third Series, Vol. III. No. 4. Svo. 1895.
transactions, Vol. XXX. Parts 15-17. 4to. 1895.
List of Members, 1895. 8vo.

1896.] General Monthly Meeting. 35

Royal Society 0/ -Low(Zo?i— Philosophical Transactions, Vol. CLXXXVI. A, Part 2,
Nos. 161-167 ; B, Part 2, Nos. 129-132. 4to. 1895.
Proceedings, No. 353. 8vo. 1895.
Salford, County Borough — Forty-seventh Annual Report of the Museum, Libraries

and Parks Committee, 1894-95.
Sanitary Institute— Journal, Vol. XVI. Part 4. 8vo. 1895.
Saxon Society of Sciences^ Royal —
Matliematisch-Physische Classe —

Abhaudlungen, Band XXII. Nos. 2-5. 8vo. 1895.
Philologisch-Historische Classe —

Abbandlungen, Band XV. No. 4. 8vo. 1895.
Scottish Microscopical Society — Proceedings, 1894-95 (pp. 177-272).
Scottish Society of Arts, Royal— TransRctions, Vol. XIV. Part 1. 8vo. 1895.
Selborne Society — Nature Notes for Dec. 1895 and Jan. 1896. 8vo.
Smithsonian Institution — An Account of the Smithsonian Institution. By G. B,
Goode. 8vo. 1895.
Index to the Literature of Didymium, 1847-93. By A. C. Langmuir. 8vo.

1894.
ludexes to the Literatures of Cerium and Lanthanum. By W. H. Magee. 8vo.

1894.
On the Densities of Oxygen and Hydrogen and on the Ratio of their Atomic
Weights. By E. W. Morley. 8vo. 1895.
Society of Arts — Journal for Dec. 1895 and Jan. 1896. 8vo.
Statistical Society, i2o?/a/— Journal, Vol. LVIII. Part 4. 8vo. 1895.
Stochholm, Royal Swedish Academy of Sciences — Bihang, Vol. XX. 8vo. 1895.
St. Petersburg, Academic Impe'rialedes Sciences — Bulletin, Fifth Series, Tome III.

No. 1. 8vo. 1895.
Tacchini, Prof. P. Eon. Mem. R.I. (the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXIV. Disp. 9-12. 4to. 1895.
Toulouse, Societe Arche'ologique du Midi de la France — Bulletin, Serie in 8vo,

No. 15. 8vo. 1895.
United Service Institution, Royal — Journal, Nos. 214, 215. 8vo. 1895.
United States Army, Surgeon- GeneraVs Office — Index Catalogue of the Library

of the Surgeon-General's Office, Vol. XVL 8vo. 1895.
United States Department of Agriculture — Monthly Weather Review for June-
July, 1895. 4to.
Climate and Health, Nos. 3, 4. 4to. 1895.
Report of Chief of Weather Bureau for 1893. 8vo. 1894.
United States Department of Interior, Census Office —
Report on Transportation Business in the U.S. at the Eleventh Census.
Part 2, Transportation by Water. 8vo. 1894.

Report on Manufacturing Industries in U.S. at the Eleventh Census. Part
3, Selected Industries. 8vo. 1895.
United States Patent 0//ice— Official Gazette, Vol. LXXII. Nos. 7-13; Vol.
LXXIII. Nos. 1-9. ' 8vo. 1895.
Alphabetical Lists of Patentees and Inventions for 1895, Part 1. 8vo. 18C5.
Annual Report of the Commissioner of Patents for 1894. 8vo. 1895.
Universal Publishing Co. — Essays by Lady Cook on Social Topics. 8vo. 1895.
Verein zur Beforderung des Gewerbfleisses in Preussen — Verhandlungen, 1895:

Heft 10. 4to. 1895.
Vienna, Geological Institute, Royal — Verhandlungen, 1895, Nos. 10-13. 8vo.

Jahrbuch, Band XLV. Heft 1. 8vo. 1895.
Washington, Natural Academy of Sciences — Memoirs, Vol. VI. 8vo. 1893,
Wright & Co. Messrs. John (the Publishers) — A Pharmacopoeia for Diseases of the

Skin. Edited by J. Startin. 4th ed. 16mo. 1896.
Yorkshire Archaeological Society — Yorkshire Archaeological Journal, Parts 53, 54.

8vo. 1896.
Zoological Society of London — Proceedings, 1895, Part 3. Svo. 1895.
Transactions, Vol. XIII. Part 11. 4to. 1895.

D 2

36 The Hon. John Collier [Feb. 7,

WEEKLY EVENING MEETING,
Friday, February 7, 1896.

Basil Woodd Smith, Esq. F.E.A.S. F.S.A. Vice-President,
in the Chair.

The Hon. John Collier.

Portrait Painting in its Historical Aspects.

(Abstract.)

The lecturer began with the consideration of portraiture in classical
times.

Although no direct evidence was obtainable until the late and
altogether debased portraits found in the Fayoum, yet from indirect
evidence we might gather that portraiture amongst the Greeks and
Eomans was a very dignified and charming art, probably a little
tame and lacking in character, but at its best more full of beauty
than it has ever been since.

The likenesses of the dead found in the Grasco-Eoman cemetery
of the Fayoum were then discussed. It was pointed out how
strangely tJaey resembled the art of another very debased period — the
early Victorian.

Portraiture was then shown to have sunk under the burden of an
increasing formalism, until in the early middle ages it had practically
ceased to exist.

It first reappeared when Italian painting was brought back to life
by the genius of Giotto. Eeference was made to his great fresco of
Paradise, in the lower portion of which is a likeness of Dante
walking in procession with his fellow citizens.

The next decided advance was ascribed to Masaccio, the forerunner
of the great fifteenth century masters, who were all in the habit of
introducing portraits of their friends into their subject pictures.

But the modern practice of having separate portraits of individuals,
was shown to have sprung up with the great painters of the Eenais-
sance — who also were the first to utilise the full resources of light
and shade, by which the vigour of portraiture was so much enhanced.
It also owed a great deal to the introduction of oil painting and the
consequent spread of easel pictures.

After alluding to the art of Leonardo and of Eaphael, the lecturer
referred to Titian as the great portrait painter of the Eenaissance.
He considered that Titian was, on the whole, the greatest painter who
had ever lived, but not quite the greatest portrait painter. Both
Eembrandt and Velasquez gave more vitality to their likenesses, but

1896.] on Portrait Painting in its Historical Asjjeds. 37

in the rendering of human beauty and dignity Titian surpassed
them both.

Titian's female portraits were apt to be stiff; in proof of this his
likeness of Catarina Cornaro was thrown on the screen, and it was
shown how oppressed the sitter seemed by the over-gorgeousness of
her clothes. This tyranny of clothes was said to have hampered the
female portraits of all the old masters.

Then Moroni was referred to as the first example of the specialised
portrait painter, i.e. one who painted very little else than portraits.

The early Flemish school was then considered as exemplified by
the Van Eycks.

It was pointed out how lacking they were in the feeling for beauty
which so distinguished the Italian school.

The lecturer then went on to Holbein and the German school.

Holbein was pronounced hard and dry in painting, but so supreme
in draughtsmanship that he gave more of the intimate character of
his sitter than any other painter.

The lecturer considered that the Dutch school of portraiture was,
as a school, the greatest of all. At the head of it stood Rembrandt,
but it included a great number of other admirable portrait painters.

As a painter, Franz Hals was pronounced over-rated — his flesh
painting was poor, but his gift of animated draughtsmanship could
hardly be excelled.

Van der Heist's great picture of the ' Banquet of the Civic Guard '
was thrown on to the screen, and referred to as a supreme example
of patient skill.

Rembrandt was bracketed with Velasquez as one of the two greatest
portrait painters who have ever lived.

His ' Syndics of the Cloth workers' Guild ' was shown, and was
pronounced the finest example known of a simple portrait group.

Then the lecturer discussed Rembrandt's only rival in his own
line — Velasquez.

There was no great Spanish school of portraiture. Velasquez
stood practically alone. In some respects he was even greater than
Rembrandt. Although a master of chiaroscuro he did not play tricks
with it as Rembrandt did, and his colouring was less artificial. On
the other hand, his portraits were sometimes stiff, which Rembrandt's
never were.

The celebrated picture of the ' Surrender of Breda ' was shown and
discussed. It was said to be something between a portrait piece and
an historical painting, and to be of the very highest excellence in
either aspect.

The lecturer then returned to the Flemish School as represented
by Vandyke — a man of great talent, but who had an unfortunate
influence on art. His extravagance led him to turn his studio into
a sort of manufactory, in which by the aid of assistants he turned out
a great number of mannered and superficial portraits. This manu-
factory was reproduced with great fidelity by Sir Joshua Reynolds,

38 Portrait Painting in its Historical Aspects. [Feb. 7,

who, with Gainsborough and Eomney, established for the first time a
purely English school of portraiture. The different characteristics
of these three men of genius were then discussed.

They were all three pre-eminently successful with women. In
their hands, for the first time since the classical epoch, had female
portraiture completely freed itself from the tyranny of stiff clothes
and stiff attitudes. For female charm and grace their works were
quite unrivalled. The male portraits were pronounced less satisfac-
tory. There was an imperfect rendering of form and a general lack
of vigorous drawing. The hands especially were very poor. These
three painters were all very prolific, and although their finest works
were in many ways admirable, their average productions were very
slight and very much scamped.

The lecturer summed up his complaint against these men of genius
by saying that they allowed their feeling for grace and charm to
overcome their love of truth. There was a great lack of sincerity in
these courtly painters, and for the highest form of portrait painting
sincerity was absolutely essential.

This was the last of the great epochs of portrait painting — Sir
Thomas Lawrence, a man of great ability but of false ideals, started
a decadence that reached its low^est depths in the early Victorian
era. The lecturer preferred not to discuss the burning subject of
modern painting. He merely remarked on the excessive love of
novelty and of eccentricity that characterised it. He ended up by
maintaining, in the teeth of modern art theories, that it was better for
a portrait to resemble the person it was meant for, or that if this
was too much to expect, that it should at least resemble a human
being.

[J. C]

1896.] Fish Culture. 39

WEEKLY EVENING MEETING,
Friday, February 14, 1896.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

J. J. Armistead, Esq. Member of the Eoyal Commission on
Tweed and Solway Fisheries.

Fish Culture.

I NEED hardly for a moment dwell upon the importance of the subject
upon which I am about to address you this evening. Fish culture
has made very rapid strides during the last few years, and its progress
and success have given those who are engaged in it opportunities of
becomiug much more intimately acquainted with some of its advan-
tages, and also with the proper use of the great motive power which
has been placed in the hands of man by an all-wise Creator.

Although a knowledge of fish culture seems to have been lost for
a long period, yet there is every evidence that it was well known to
the ancients. The Chinese at the present day are well acquainted
with fish culture, and have been so from time immemorial. They
have curious methods of placing bundles of sticks and mats in the
rivers, on which the fish deposit their ova, which afterwards become
a marketable commodity. There is no doubt whatever that fish
culture was well known to the ancient Greeks, and Eomaus also, but,
as their knowledge has not been handed down to the present time, it
might as well, so far as we are concerned, have never existed. It is
said of LucuUus, that at Tusculum he caused canals to be dug between
his fish ponds and the sea, so that when the fish came up from the sea
to deposit their eggs in the fresh water, he was enabled to intercept
them by placing gratings in these canals, and while their posterity
were growing the fish themselves furnished the market. That fish
were held in high esteem in the olden time is very evident. They
were patronised by the Csesars. Augustus had a fish engraved on
his signet ring, and they appeared upon coins not only during his
time but long afterwards, and the coins of Greece were similarly
embellished. Towns, islands, ships and taverns were named after
them, and from the same source ancient literature is said to have
derived some of its prettiest similes, myths and fables. They were
also sacrificed to the various deities. But, notwithstanding this, the
ancients seem to have set far greater store upon fish as articles of
food in most cases, than as objects of worship. " We remember the
fish which we did eat in Egypt," was the cry of the Israelites after

40 Mr. J, J. Armisiead [Feb. 14,

the Exodus, from which one would infer that they might have
preferred fish to freedom.

Coming down to later times, fish culture, or rather the secret of
fertilising ova by artificial means, was discovered by a German
naturalist, Count Von Golstein, about the year 1758. It also became
known to another German naturalist, one Jacobi, a short time after-
wards, about the year 1761, and strange to say he not only succeeded
in fertilising eggs, but he fertilised the eggs which he took from a
dead fish. However, notwithstanding this, no practical use seems to
have been made of the knowledge which was obtained till nearly a
century afterwards, down so lately as the year 1841, when it fell to
the lot of two French peasants to discover the fact that trout ova
could be fertilised artificially, and that they could be hatched. These
men could never have heard of the scientists who were acquainted with
the scientific experiment which had been discovered so long before,
but they found from studying the habits of the fish in their native
streams that the eggs were deposited in the gravel ; and, following
out nature's plan, these men collected a quantity of gravel from the
stream bottom and fertilised the eggs, and placed them among gravel,
and placed this in a perforated tin or zinc vessel, something in shape
like a cheese, and put this at the bottom of the stream where the
current would percolate through the holes and so keep up a continual
supply of water. In due course of time the eggs hatched. But for a
long time the thing went no further. People supposed that the
gravelly bed of the stream was an absolute necessity for the hatching
of the ova of trout. At last, however, the matter was taken up by
the Societe d'Acclimatation de Paris, and Professor Coste conceived
the idea that eggs could not only be fertilised, but could be incubated
and hatched, and the little fish reared to maturity, apart from the
natural streams, and he proved his assertion by hatching some salmon
in a tub. He got a large tub and in it he placed a number of boxes
in such a position that the water flowed from one to the other round
the tub. In these boxes he placed his ova, and in due course of time
they hatched and produced fish. This was about the year 1850.
Then I come down to a later time in the history of fish culture, and
one which I cannot but remember with feelings partly of regret at
the fact that the operator is no longer with us. I refer to the late
lamented Frank Buckland, who some thirty-three years ago stood
upon the platform which I have the honour to occupy to-night.
Buckland said of fish culture that it promised "to be eventually
the origin of increase of revenue to private individuals, a source
of national wealth, and certainly a great boon to the public in
general." This was thirty years ago, and hpw do we stand to-day ?
The first part of that prophecy has been amply fulfilled, and the last
part of it has been and is being fulfilled in many places. The third
part of itj which comes in the middle, is to be fulfilled as soon as
Government will take the matter up, for that alone can make the
subject become a source of national wealth. In Germany, fish culture

1896.] on Fish Culture. 41

has been very largely taken up, and all those who are familiar with
it are well acquainted with the names of Herr Max Von dem Borne
and others, who have experimented largely and carried the work to
great perfection.

In America, also, a great deal has been done, and the American
Government some time ago started a United States Fish Commission
which is carried on under Government auspices, and devotes attention
not only to the stocking of the rivers and the lakes, but to what is
more important, the study of the fish themselves, of the animals upon
which they feed, of the plants surrounding them in the waters in which
the fish live, and of anything else of importance in connection with
them. A great deal of work, and very important work, has been done,
and much of our knowledge at the present time has come from the
United States and from Canada.

The principle of the artificial incubation of ova is a current of
water. It may be a current flowing or rising up perpendicularly or
flowing horizontally. In nature we find the eggs deposited — I am
alluding now to those of the salmonidae — in the gravel at the bottom
of streams, and we find where they are deposited that the water comes
welling up from below through the gravel, and that the eggs obtain
thus a sufficient supply of oxygen, and in due course of time hatch.
This was followed out for many years by fish culturists, a current of
water being caused to flow into the hatching apparatus at the bottom
and to flow out at the top, so that it rose up amongst the eggs ; and
practically this has been carried out with more or less modification
until the present time.

The hatching apparatus which is used now chiefly in this country
consists of a long box, the water flowing in at one end protected by a
water board or breakwater, which is simply to break the current and
prevent it from washing away the eggs which are placed in the
box. It also diverts the current and sends it down to the bottom
of the box. The water passes underneath and passes out at a higher
level, where we have a screen of perforated metal to prevent the
escape of the little fish, and in this box is placed the hatching appa-
ratus proper, that is, the trays or grilles upon which the ova are
deposited. The grilles now in use are made of glass. We found
after trying a variety of substances, that glass is the best of anything.
It gives oft' nothing. Wood and metal we know corrode in water, and
in some waters some metals corrode very much, and a great deal of
loss has been suffered by some who have used metallic trays for the
purposes of incubation. The Americans like to do things as we know
on a wholesale scale, and, not content with putting a layer of eggs
upon the apparatus, they fill a basket, as they call it, half full of eggs.
Then they send a current of water welling up from underneath, and
of course the effect is that it flows through amongst the eggs, and
they find that in due course of time they hatch. I have made very
careful inquiries with regard to the result of the hatching of ova in
this way, and I have found that the Americans are quite prepared

42 Mr. J. J. Armistead [Feb. 14,

to admit that they had a larger percentage of mortality in their
metal baskets or trays than they had when they used glass grilles.
They said " we have discarded glass grilles long ago. They are too
expensive"; and they made use of other excuses. But, however,
we find in practice that we can get far better results from these
glass grilles, because, as I have said, there is nothing to contaminate
the ova or do them any injury. The trout eggs absorb any metallic
matter which may be in the water, and become so saturated with it
in course of time as to be very seriously injured. They may not be
absolutely killed at the time, but it has been found that, although
there is only a slightly increased mortality in hatching upon the metal,
there is a greater mortality amongst the fish afterwards. They do
not live to grow up in the same way as they do when they are hatched
on the glass. I have here certain little imjjlements which are used in
the hatchery for working amongst the ova and the little fish. There
is a dipping tube which is used for picking up a fish for exami-
nation in the hatching boxes. These are some young trout which
I have in here, and they are called " alevins." They are easily picked
up in these tubes, which are of different shapes. For all these
difierent appliances, and a great many others, we require a house of
considerable dimensions in which to put them. I will show you now
a view in one of my hatcheries (Fig. 1).

First of all the water enters the building, and flows along a
distributing tank. There are two of these tanks, one containing
spring water and the other containing river water. The spring water
we find very much the best of the two for incubation, and the river
water much the best for growing the fish, so that we can turn on
which we like, to suit circumstances as the process goes on. There
are pipes by which the water is conducted to the hatching boxes.
The hatching boxes are covered with lids in order to keep the fish in
the dark. In the natural stream the eggs are buried in the gravel,
and we find that light is decidedly injurious to
the little embryo trout after they hatch ; so we
keep them in the dark.

These are fish-carriers used for sending away
the fish after they have grown (Fig. 2). We
put ice in the upper, and the fish in the lower
part, and there is a screen of perforated zinc
which prevents the ice tumbling in, and as it
melts it drips down and keeps the water cool.

There is another view in another hatchery,
where we have a tank which is used for spawn-
ing pui'poses, the fish being thrown in after
Fig. 2. they are spawned, the spawning operations be-

ing conducted alongside. I am very sorry that
they were not going on at the time that the photograph was taken.
But the fish, after having the ova stripped from them, are put into the
tank for a short time until they can be taken away.

1896.] on Fish Culture. 43

In the tank are the bowls or dishes which are used in taking the
ova. The eggs are expressed into these dishes. The milt is ex-
pressed upon them, and the two mingled together, and after a while
they are washed, and the eggs laid down in the hatching boxes. In
order to have purity of water — I do not mean chemical purity, but
freedom from matter held in suspension — we have to use a system of
filtration, and one of the first processes is to filter the water as it
comes from the stream itself, and for a long time we had a great deal
of trouble in doing this, because the screens which we use choke up
and require a great deal of attention, and sometimes cause disaster
by being overlooked. We have now got a system which works for a
whole season without the slightest attention. Once j)ut it in order,
it regulates itself. If we imagine this model to represent the bed of
the stream — the sheet of perforated zinc here, and the stream flowing
through this box — you can see that the water passing through leaves
behind on the zinc anything in the shape of leaves and small pieces of
stick and other matters which are floating in it. We found that by
setting this at a certain angle if we had twice as much water flowing
over it as we had going through the zinc it never stopped ; and
so, applying this principle, we are able now to run the whole year
through without the slightest trouble. The water passes through the
zinc into the box, and passes out at the hole at the end, and is drawn
off to sujDply the hatchery.

There is a tank house or place where the water is filtered. Here
we have some concrete tanks in which the water is allowed to settle.
They are settling tanks in fact. After settling, the water flows from
these tanks into a filter box, which is full of wooden screens covered
with flannel through which the water passes. This takes away any
sediment which may still remain, and the water comes out perfectly
pure, passing on into the hatchery.

Having got the hatchery in order, we have to take the eggs from
the fish, and this is done first of all by netting tbem, and then sorting
the difterent kinds into difi'erent vessels, and taking them when they
are ripe; that is, when they are ready to yield their ova, and by
gentle pressure the eggs are quite easily stripped from them. In
America this is done with large fish, where a great many have to be
done, by putting them into a wooden box by which the head is locked
so that it cannot move, and the eggs are taken from it. In this way
a large number of fish, like salmon, can be manipulated in a very
short time. Here we have a sort of spawning tub. The fish have
been taken from a store pond, and are now in the net. Here are
the tubs and receptacles into which they are about to be put and then
sorted (Fig. 3).

Another photograph will show the next process : a lot of fish being
taken and put into tubs. There are the spawning tubs all ready, and
the spawning table used in this operation is also shown. The eggs
are carried down to the hatcheries and laid down in the hatching boxes.
There they remain for a period of something like three months, the

44

Mr J. J. Armistead

[Feb. 14,

incubation going on meanwhile ; and I do not know that there is a
much more interesting sight than to watch the development of the
embryos. First of all, a short time after laying the eggs down, we find
the process of segmentation setting in. There is first a cell, and then
a division into two, then into four, then into eight, and sixteen, and so
on ; and so the process goes on till at last we can detect the chorda
dorsalis, or notochord ; and at last we see two little black specks
which are the eyes of the fish, and when we see this we know that the
eggs are almost in a state to bear packing for New Zealand or
Australia. We have sent a great many eggs out to New Zealand and
Australia, and a great deal of trouble was occasioned in the early
days of fish culture by not knowing the exact time at which to pack
them. We have found that very soon after the eye-spots appear there
is a perceptible motion of the tail of the fish, and also the first appear-
ance of red blood. When we see that, we know that the eggs are fit
to be packed, and they travel beautifully on the long voyage to the
Antipodes. Here we have the tubs and the operator, and the fish
ready to spawn. In due course of time the eggs hatch. The little
fish does not look very much like a fish at first. They are very
lively and very interesting creatures. Some of the bottles contain
ova of trout. One bottle has the ova of salmon in it. The salmon
eggs are marked, and the trout eggs are not, so that the mark on the
bottle shows which sort it is. There are the little fish in what we call
the alevin stage, with the umbilical sac attached (Fig. 4). Through

Alevin.

a microscope you get a most interesting sight by looking at these little
fellows. You can see the circulation of the blood, and the sight is an
exceedingly interesting one. Very naturally, delicate little things
like these require a great deal of care. Notwithstanding, we have
worked the thing to such a point now that we have very little trouble
with them during this stage of their existence, if the hatchery appara-
tus be kept clean. The little pectoral fins are continually moving,
and cause currents of water which are passing through the gills, so
that the little fish get a supply of oxygen. If we keep the boxes free

1896.] on Fish Culture. 45

from sediment and pollution, we find tliat we have no trouble with
the fish in this stage. A little later on, however, the fi.sh-culturist's
troubles begin. The fish begin to feed. The umbilical sac is almost
absorbed, and we find the fish rising in the water. Hitherto they
have remained pretty much on the bottom, but now we find them
rising in the water, heading the current, and to all intents and pur-
poses looking out for food, showing that they are hungry. When we
see this we have to begin to feed them. Naturally they have very
little mouths, and the difiiculty is to find food which is sufficiently
small for the little fish to swallow. We have managed to get a
good many substances in the shape of artificial food upon which
they can be fed, but we find that if we go to nature and take a leaf
from her book we can get very much better food in the shape of
entomostraca, which can be grown in very large numbers, and upon
which the fish thrive very much better than they do on the artificial
foods.

It is very natural that with such delicate beings there should
be great losses when left to nature, and here is one of the great
advantages of fish culture. We can save 95 per cent, of the eggs
laid down, whereas if left to nature probably not more than 25 per
cent, would ever hatch. Frank Buckland estimated that one egg, or
" not one egg," I think he said, in every thousand produced a mature
fish, and I do not think that he was far off the mark ; so that we
see that there is an enormous loss continually taking place in our
rivers and streams. It is called a " loss," but I would rather say
that these little fish are disposed of by natural means. There is
no real loss. We do not recognise such a thing as " loss " in
nature. The fish are disposed of by natural means. Nature has
arranged so that the enormous numbers of eggs which are deposited
should not hatch. We can see that if they hatched the result would
be that there would be far more fish in the rivers than the rivers
could possibly contain, and therefore there is this great destruction
of the ova of the fish in their early stages ; whereas, by artificial fish
culture, we can save a very large percentage, so that by cultivating
the water and making it capable of holding a larger quantity of fish
than nature would allow, a great deal may be done, and the supply
of fish may be largely increased.

What happens to the salmonidas of which I have been speaking,
happens on a much larger scale to a great many of our marine fishes,
and man has a power given Lim of counteracting this great loss.
We have now some marine hatcheries, and a very good work is being
begun in those hatcheries. I was at one at Dunbar a little while ago,
and saw the work which is being carried on there by Captain
Dannevig. He has a series of boxes for hatching ova, and, unlike
the boxes which I have here for hatching ova which require to be
kept perfectly still, these pelagic ova, accustomed to the motion of
the waves, would not do when they were kept in boxes in a state of
quiescence, and therefore by means of machinery the boxes are made
to move up and down, and the eggs are constantly being slightly

46 Mr. J. J. Armistead [Feb. 14,

agitated, and you get a motion wliicli is very akin to the motion
produced by the waves of the sea, and the results have been found
perfect. Before this was obtained a great many difficulties were
in the way. The eggs refused to live, and they got matted together,
and the modes that were used were to a certain extent imsuccessful.
Captain Dannevig has got over the difficulty ; and so I believe every
difficulty that we have to contend with in fish culture may be got
over if we only persevere and strive to overcome these hindrances.

The way in which the loss may be counteracted with regard to
our fresh-water fishes is evidently by taking care of the eggs. It is
amongst the ova and the fish in its embryonic stage that the great
loss occurs, as I have said ; so, by making artificial ova beds and
laying the eggs down in them in places where the enemies of the fish
cannot get in, the eggs can rest there in perfect peace, and can be
allowed to hatch. The little fish after they come out can be cared
for and protected from their enemies until they have grown to such
a size that they can care for themselves; and it is astonishing to
see how soon nature teaches them to do this, and how soon they get
into the way of finding out shallows, and finding out eddies, and
getting behind stones and under cover, and keeping away from their
chief enemies, which, I am sorry to say, are often their own parents,
or, anyhow, fish of their own species.

These ova beds are constructed just on the same principle that
the hatching boxes are constructed in the hatchery, with this differ-
ence, that the eggs are hatched among gravel instead of glass. We
place some perforated zinc a little way from the bottom of the box,
and on that some gravel, and place the eggs among it. The water
flowing down to the bottom of the box wells up through the gravel,
and so the eggs are incubated successfully. In this way enormous
numbers of ova can be hatched, and this plan has been already tried
on some of our streams, and has been found to be most successful.
The cost is very trifling, and, altogether, fish culture promises in
future to do a great deal for many of our rivers.

I have spoken about the young fish beginning to feed. When
they begin to feed their troubles really begin. The artificial foods
upon which they are fed very naturally give them indigestion, and
they suffer from this and from a number of other complaints ; and
the consequence is that we lose a great many of them. At the present
time, if we succeed in rearing one-half of the fish that are hatched,
we consider that we are doing very good work. A little while ago,
the percentage was less than this. It was about one-third, or 33 per
cent, of the fish that were hatched, and this was considered very
good work. I believe that we shall very soon get on to raise the
percentage to 70 or 80.

Here we have some fry ponds for rearing the fry (Fig. 5). After
the latter have begun to feed, they are left in the hatching boxes a
short time, just to ge'c accustomed to it. Then they are taken out and
put into these narrow ponds, and we have a current of water running
through the ponds, and the young fish thrive there, and are fed four

i Q

\ Ah

^^^^^m'm^-

1

1896.] on Fish Culture. 47

or five times daily. The feeding requires a great deal of skill and
experience, and it is thus no light matter. It would take a man the
whole of his time to look after a series of ponds like this, and to
attend duly to the fish in them, without doing anything else.

This is another series of fry ponds on a piece of level ground
(Fig. 6). There we have them rather on a hillside, with a good fall
from one to the other, and we find the benefit of that in growing the
little fish. Some do very much better than they do when the water
has not much fall. The ponds are very much of the same description
as the others. We have here at each end a screen to prevent the
little fish getting out, and the water flows in at one end and out at
another, and then on to the next pond, and so on.

Then the little fish in due time grow to the size which we call
yearlings. They are not really a year old, but it seems to be the
best name to give them for distinction, and as they are yearlings when
they are really a year old and some time after, it seems quite fair to
call them yearlings before they have actually lived twelve months.
The time that they pass from the fry stage to the yearling stage may
be said to be the time during the summer months, when the weather
is too warm and the temperature too high to send them very long
journeys for stocking rivers and lakes. As soon as the cold weather
comes, at the end of August or September, then the fish can travel by.
rail and otherwise, and they rejoice in the name of yearlings.

The scene here represents the preparation of the yearling fish for
a journey (Fig. 7). They cannot be taken out of the pond and sent
away at once. We had great losses some years ago in doing this.
The fish were put into the carrying tanks and sent off, and we had
to make elaborate arrangements for changing the water during transit,
which has been found since to be one of the very worst things that
can be done, and now we never change the water except as a very
last resource, in case of some unlooked-for emergency. The fish
are taken out of the pond and confined in these tanks with water
running through them for a considerable time — two or three days at
least — and in there they are not fed. We find that they travel very
much better on empty stomachs than they do after a meal, and, as it
does not seem to do them any harm to starve them a little, we do not
feed them before sending them away, and we find that the result is
perfectly satisfactory. These are the cans which I described before
for putting them in. They have the ice on the top, and the fish in
the cavity below.

Now, what is the outcome of all this ? We have cultivated fish
now for thirty years or more, and we have got to know a good deal
more about them than we knew at the beginning of that time. Well,
we find on looking round that a great many, in fact a large majority,
of the streams of this country are in their present state almost
worthless. They will not hold trout of any size, and it is very
difficult indeed to get good fishing. Little worthless brooks have, in
cases where they have been dealt with, been made to produce tons of
fish, and one — a brook which practically would not produce fish at

48 Mr. J. J. Armislead [Feb. 14,

all, naturally, and the trout in whicli were so insignificant in size as
hardly to be worth noticing — from a fisherman's point of view I am
speaking now — was made to produce tons of fish. One pond alone
produced several times over, upwards of fifteen hundredweight of fish.
The pond was only ninety feet long by thirty feet wide. Of course
the fish hsid to be largely fed on artificial food, but by using the
artificial food twice a day the ponds produced a large quantity.
This shows what water may be made to do ; and when we hear
about the over-crowding of fish in our rivers and lakes, it strikes a
fish-culturist sometimes as being the height of absurdity. We find,
however, in our streams that there is often little or no water, and
that the fish are run back into the pools and have to wait there a
considerable time until a flood comes, or until a shower comes which
causes the stream to rise, and during this time they get very little
food. The food supply in the streams, owing to the lowness of the
water, is almost destroyed, and the animals which inhabit the streams,
like the fish, suffer very much from the lowness of the water, which
is caused very largely by the surface or hill drainage which has been
carried on for thirty or forty years in this country.

Now, all this can be counteracted, I believe, very easily. Na
doubt we have a great deal to learn about it yet, but we are on the
right tack, and I think that after a while we shall be able to remedy
this state of things to a large extent. We find that from this state of
lowness of water we suddenly drift into a state of heavy flood. The
rains come down, and the water comes down from the hills in heavy
floods — -far heavier than came down before the hills were drained.
These floods carry everything before them, sometimes washing away
bridges, and doing more or less damage to property. Now this
water must be put under control, and when we get it under control
we find that it is, indeed, a most controllable thing. We find that
we can do with it what we did not anticipate but a few years ago.
At those times of the year V7hen the water supply is naturally
deficient, it must be gently increased, and I need hardly point out,
that by caring for it even to this extent, one of the natural conse-
quences will be an increase in the quantity of that class of food
which is produced in the stream itself, or in its immediate sur-
roundings or accessories. The fish, too, will at once have a better
range, and so will feed more freely than they do when confined in a
pool where starvation has become a necessity on the one hand, and
escape a practical impossibility on the other. In addition to having
become possessed of more roomy quarters, the whole tone of their
surroundings has become better. The water in which they live,
and on which their very existence depends, has become fresher and
contains more oxygen. The fish feel and enjoy a freedom which
before they were unacquainted with ; and, in addition to this, if a
sufficiency of proper food be forthcoming, they will at once begin to
put on flesh and grow in a surprising manner.

The water supply can very easily be managed by impounding, and
by making reservoirs on the streams so that compensation water can

1896.] on Fish Culture. 49

be let off during dry weather. In tliis way the streams can be kept
up to their proper limits. They need never run so low as they have
been accustomed to do. But we find that by impounding water the
floods are lessened, and therefore that great scouring process which
goes on in the streams, destroying both animal and vegetable life, is to
a great extent lessened, and everything living in the water has a very
much better chance of existence than it had before.

The desired result cannot be obtained by making one simple dam
upon a stream. Take a river for instance : if we make a dam, as has
been suggested — and one or two places of the kind have been made up
at the head of the waters of some streams — when the water is let off
as compensation water it is found, in one case which I remember,
that when it has run eight miles, after being started as a roaring torrent
from the reservoir known as Lake Vyrnwy in Wales, the stream is
not very j3erceptibly affected. I believe that it was raised about one
inch ; but there are other tributaries coming in, and if there were
reservoirs on these other streams, and we had compensation water let
off from them, we should get a rise of several inches instead of only
one inch, and we should find that the result would be very beneficial.

I remember an attempt being made to bring up sea fish by an
artificial spate at a place in Scotland, and it was eminently successful.
The landed proprietor there blocked up the outlet from one of tlie
lakes, and then when the salmon were waiting to come uj) the river
he let off the water from this impounded lake, and the consequence
was that he got a good run of fish. So successful was it, and so
pleased was he, that he very soon tried it again, but the second time
it was just as unsuccessful as the first time it had been successful.
The consequence was that they came to the conclusion that the fish
had found before that they had been deceived, that there had not
been really a spate, that it had not been raining at all ; and therefore
the next time they fought shy of it and would not come up. When I
came to make inquiry I could not find that there had been any fish
waiting to come up ; and when these artificial spates are made it is
necessary to be exceedingly careful to make them not only in the
right way but at the right time. In one instance water was let off
from a reservoir very near the bottom, the bank being, I think, some-
thing like eighty or ninety feet high. The water was let off at a
level very near the bottom of the reservoir. Now, if the water had
been let off from a level near the surface it would have been very
much more beneficial to the fish. The water low down in a reservoir
contains very much more matter in suspension, and it is of a very
different nature from the water on the surface; and so, for fish-
cultural purposes we must take the water from the surface of the
lake, or as near it as possible, and then we may expect the fish to
appreciate it and follow the spate. Sometimes the fish do not want to
go. Well, it is of no use to make a spate then. If the fish do not
want to run you may let off water, and you may do what you like,
but you cannot make them go. But in my experience, and I have

Vol. XV. (No. 90.) " k

50 Mr. J. J. Armistead [Feb. 14,

tried a good many experiments on trout, I have found that nothing is
easier than to make trout run when you get an artificial spate at the
proper time and made in the proper way.

In the case of sea fish there are some very important things to be
considered. First of all we have the sea to contend with. The fish
are coming up from the sea. Now we find that the anadromous or
sea-going fish run on flood tides, and we know that they enter the
river usually a little before high water, so that to let in the spate on
an ebb tide would be absolutely useless. Then, again, we find that
the wind has a great deal to do with the run of fish. On our
west coast, or on some of our west coast rivers, when we get a wind
from the westward we find, other things being equal, that the fish
will run very much better than with an east wind. They will often
hardly run at all with an east wind, even though other things may be
favourable ; so that the wind is an element which has to be con-
sidered. Barometrical conditions have also to be considered, and we
find that they play a very important part indeed in influencing the
movements of our fishes. Then we find, above all, that, although
the fish run upon a flood tide, on spring tides they run very much
better than they do on neap tides, when they often run very tardily ;
so that by takiug advantage of a knowledge of these facts and others,
we can let ofi" impounded water at a time when it will be likely to
bring them ; aud there is no doubt whatever that if the thing were
properly carried out it would be eminently successful. As regards
trout, a very moderate amount of water is sufficient to produce very
great results. I have seen a stream utilised which ran almost dry
in dry weather. The water of the stream has been made to produce
a large quantity of fish, as I have just described.

Here we have such a stream (Fig. 8), but with a rocky bed
almost dry. The water retires into the pools in which the fish live
during the times of drought. On this stream we have a dam made to
run across, and raising the water some three feet above its natural level.
Here, where the man is sitting, is a sluice, and the water is allowed
to escape through this sluice, which regulates the supply, and it flows
away into the woods. It passes through a pine forest, and by
means of this aqueduct goes on. Here is another view of the same
aqueduct, and so it goes on flowing for a distance of about half a mile,
the country through which it passes being from many circumstances
unfavourable for the coustruction of ponds. That, however, is no
great difficulty. It is simply a case of taking the water a little
farther on until we get to a suitable place for the construction of the
ponds in which the fish must live. The spout or bridge is to conduct
the surface water or rain water over the aqueduct, and to prevent its
getting in in excess. The surface water, if allowed to get in in excess,
has a prejudicial effect, so we employ a large number of these little
bridges for the purpose of keeping it out. Little canals are dug in
various directions for conducting the water into these spouts. The
water passes on and flows into this pond here, and in this pond a
large number of fish have been produced.

1896.] on Fish Culture. 61

The pond lias to bo cultivated. The water is cultivated not only
as regards the fish, but as regards the vegetation which is in it. A
large number of plants are introduced both into the pond itself, and
also into accessory ponds ; and this is one of the most important
branches, perhaps, of modern fish culture — the growing of the food
upon which the fish live. Into the accessory ponds we can introduce
creatures which multiply enormously under favourable circumstances ;
and we find that these creatures can be let off in large numbers by
simply drawing the sluices and allowing a quantity of water to pass
into the fish pond, and that the fish then take them. A sufficient
quantity are left behind to keep up the supply, and the pond is re-
filled with water ; and so, by having a few of these ponds constructed
we can keep up a very fair supply of food for the fish. Where fish
culture is carried on on a very extensive scale, it is necessary to
supplement this supply, and in some cases to supplement it largely,
by artificial food ; but, as applicable to our rivers, it would not be
necessary to do this ; and I believe that on any river if the matter
were taken up in earnest it would be possible to do it by impounding
water so as to counteract the effects of drought in the summer,
and also to partially counteract the effects of floods by impounding
the water instead of letting it come pell-mell down the stream. By
growing food to supply the fish, we can get a very much finer and
better race of fish than we can if the matter be left entirely to nature.
We find that there are certain streams which produce very much
better fish than others. In these streams the fish are fed upon certain
creatures, and by taking care of those creatures and multiplying
them, we can produce a large amount of valuable fish food — a thing
which was never thought of years ago, but which now is coming to
the front, and probably before long the plan will be largely adopted.

This represents such an accessory pond as I have described.
You see a number of water plants growing in the water. Here are
the floating leaves in various directions, and there are others throwing
up their stems and leaves with a mass of vegetation all round. This
pond j)roduces an enormous quantity of Limnea peregra and other
creatures upon which the trout are fed. All these, it has been proved,
are easily applicable to trout and to trout waters. The plan is also
apj)licable on a very large scale to salmon rivers ; and how much
more important are salmon rivers than trout streams. How much
more important are the salmon as articles of food for human con-
sumption than the trout. And yet the salmon are being neglected,
and the trout are being cared for. We want, not exactly the reverse,
but we want to have the salmon cared for too ; and that is one of the
things that I have been trying to bring before the people of this
country for years, and I think that I may say that already my efforts
are being crowned with some kind of success.

We find that the practice of hill draining on the rivers produces a
great effect ; and what has been partly, I think, overlooked — for I have
never heard it alluded to — is that the hill drainage, by lessening the

E 2

52 Mr. J. J. Armistead on Fish Culture^ [Feb. 14,

quantity of water in the rivers, largely lessens the quantity of fresh
water which is poured into the estuaries into which the rivers flow
during times of drought. Then, on the other hand, we get the
contrary during floods, when an enormous bulk of fresh water is
poured into the salt water in the sea, and in a shall )w estuary, such
as the one upon which I live, and which is represented roughly here,
we find that, with these rivers flowing into it (the watershed of the
firth is I think something like nearly ten times greater than the firth
itself, and the firth is a very shallow one) that the specific gravity
of the water, the temperature of the water, and other things, are
tampered with to such an extent that some of the fish actually
deserted it about forty years ago, which, I think, would be somewhere
about the time that the hill drainage commenced. The herring is
one fish that has deserted the firth, and since that time it has never
to any extent come into it. Sometimes some herrings for a short time
will come in, but they are very soon out of it again, which shows
that when favourable conditions occasionally occur the fish will come
into the water ; whereas, owing to this drought altering the specific
gravity, we find the fish keeping away.

All these matters are of the greatest importance with regard to
the regulation of our fisheries, both marine and fresh water, and they
want looking into. I think that, perhai)s, one of the greatest delights,
or the greatest delight, of fish culture is that there is so much to
be learnt, and that we are always finding out something new, and
that there is always a field to which we can turn for searching out
the hidden mysteries of nature and increasing our knowledge, and
learning more about the fishes that we have been talking about.

I would have liked to say a little about the diseases of fish, but
I am afraid that there is no time. We have already over thirty of
these diagnosed, and, ^vhat is more, we have found out the means of
cure for a number of them, and we have been helping fish culture
very much in this way. Many of the diseases are parasitic, and we
find j)arasites which afiect the fish which were not known to fish-
culturists years ago. One is a curious protozoan which gets on the
bodies of the fish, and has been known to kill them in large numbers.
It can be destroyed in a rather peculiar way*, by placing the fish in a
tank with a current of water flowing through it, the bottom strongly
impregnated with salt, a saturated solution of salt. The fish keep in
the upper water, which is fresh. These curious little j^rotozoaus at
certain times leave the fish and go down to the bottom. There they
divide, and they are multiplied by division and produce enormous
numbers. These free-swimming little creatures get into the water and
swim about, and are taken up by the fish again. We find that by
having a saturated solution of salt at the bottom of the water and a
current of fresh over it, the fish live in the fresh water, and the
parasites, when they leave the fish and go down to the bottom, are not
able to reach the fish again, because they are killed at once by the
salt.

[J. J. A.]

1896.] Past, Present and Future Water Supply of London. 53

WEEKLY EVENING MEETING,

Eriday, February 21, 1896.

Sir Feederick Abel, Bart. K.C.B. D.C.L. LL.D. E.R.S.

Vice-President, in the Chair.

Edward Frankland, Esq. D.C.L. LL.D. For. Sec. K.S. 3I.i?.I.

The Past, Present and Future Water Supply of London.

In a discourse to the Members of the Eoyal Institution on the subject
of the metropolitan water supply nearly thirty years ago, I stated that
out of every thousand people existing upon this planet at that moment
three lived in London ; and, as the population of London has in the
meantime doubtless grown at a more rapid rate than that of the rest
of the world, it will j^i'^^bably be no exaggeration to say that now,
out of every thousand people alive on this earth, four live in London ;
and therefore any matter which immediately concerns the health and
comfort of this vast mass of humanity may well merit our most
earnest attention. Amongst such matters that of the supply, in
sufficient quantity, of palatable and wholesome water is certainly not
the least in importance.

It is not therefore surprising that this subject has received much
attention from several Royal Commissions, notably from the Royal
Commission on "Water Supply of 1867, j^resided over by the Dnke of
Richmond ; the Royal Commission on the Pollution of Rivers and
Domestic Water Supply of Great Britain, presided over by the late
Sir William Denison, of which I had the honour to be a member;
and lastly the Royal Commission appointed in 1892 to inquire into
the water supply of the metropolis, of which Lord Balfour of Burleigh
was chairman, and of which Professor Dewar was a member.

The Royal Institution has also, for nearly three-quarters of a
century, been prominently connected with the investigation and
imjDrovement of the metropolitan water supply, no less than four of
our professors of chemistry having been successively engaged in this
work, viz. Professors Brande, Odling, Dewar and mys(jlf, whilst three
of them have been members of the Royal Commissions just mentioned.-
I may therefore perhaps be excused for accej^ting the invitation of our
secretary to bring the subject under your notice for the third time.

On the present occasion, I propofje to consider it from three points
of view, viz. the past, the present and the future ; and for reasons
which will appear hereafter, I shall divide the past from the present
at or about the year 1883, and will not go back further than the
year 1828, when Dr. Brande, Professor of Chemistry in the Royal

54 Br. Edivard Franhland [Feb. 21,

Institution, Mr. Telford, the celebrated engineer, and Dr. Eoget,
Secretary of the Eoyal Society, were appointed a Royal Commission
to inquire into the quality and salubrity of the water supplied to the
metropolis.

The Commissioners made careful examinations and analyses, and
reported as follows : " We are of opinion that the present state of the
supply of water to the metropolis is susceptible of, and requires
improvement ; that many of the complaints respecting the quality of
the water are well founded ; and that it ought to be derived from other
sources than those now resorted to, and guarded by such restrictions
as shall at all times ensure its cleanliness and purity." (At this time
the water was pumped from the Thames between London Bridge and
Battersea). " To obtain an effective supply of clear water, free from
insects and all suspended matter, we have taken into consideration
various plans of filtering the river water through beds of sand and
other materials ; and considering this, on many accounts, as a very
important object, we are glad to find that it is perfectly possible to
filter the whole supply, and this within such limits, in point of
cxj^ense, as that no serious objection can be urged against tbo plan
on that score, and with such rapidity as not to interfere with the
regularity of service."

Before the year 1829, therefore, the river water supplied to
London was not filtered at all ; but after the issue of this report, the
companies set themselves earnestly to work to improve the quality of
the water by filtration.

The first filter on a working scale was constructed and brought
into use by the Chelsea Water Company in the year 1829. But even
as late as 1850, only three out of the seven principal companies filtered
the river water which they delivered in London ; and it was not until
1856 that filtration was made compulsory by Act of Parliament ;
whilst it can scarcely be doubted that between this date and the year
1868, when my observations on turbidity were first commenced, the
operation was very imperfectly performed.

In the year 1832, and again in 1849, London was severely visited
by epidemic cholera, and the agency of drinking water in spreading
the disease forced itself upon the attention of the observant portion
of the medical profession. It was Dr. Snowe, however, who in
August 1849 first formally enunciated the doctrine that drinking
water, polluted by choleraic matters, is the chief agent by which
cholera is propagated.

Keceived at first with incredulity, this doctrine was supported by
numerous facts, and it soon caused renewed attention to be directed
to the quality of the water then being supplied to the metropolis,
with the result that the intakes of the various companies drawing
from rivers were, one after another, removed to positions above the
reach of tidal influence, tlie Thames water being withdrawn from the
river above Teddington Lock, and the Lea water at Ponders End,
above the tidal reaches of that river.

1896.] on the Past, Present and Future Water Suj^phj of London. 55

In every visitation of Asiatic cholera to London, the water supply
was either altogether unfilterecl or imperfectly filtered, besides being
derived from highly polluted parts of the Thames and Lea ; and the
enormous loss of life, amounting in the aggregate to nearly thirty-six
thousand peoj^le, can only be attributed to this cause ; for it has now
been abundantly proved that cholera is, practically, propagated by
drinking water alone, and that efiicient filtration is a j^erfect safeguard
against its propagation. Moreover, it is most satisfactory to know
that, since the year 1854, no case of Asiatic cholera in London has
been traced to the use of filtered river water. The following table
clearly indicates the close connection between intensity of pollution
and cholera mortality : —

Cholera Epidemics in London.

Epidemic of 1832

„ 1849

„ 1854

„ „ 18G6

Character of Water Supply as
regards Excremental Pollution.

Polluted

Very much polluted
Less polluted ..
Much less polluted

Total :\Iortality
Irom Cholera.

5,275
14,137
10,738

5,596

Mortality from

Cholera per 10,000

of Population.

31-4
61-8
42-9
18-4

These are the results arrived at by the most general investigation
of the subject. They show that in every epidemic, the mortality
varies directly with the intensity of the drainage pollution of the
water drunk by the people ; but, if time permitted, a more detailed
study of the statistics in these ejndemics would demonstrate, much more
conclusively, this connection between cholera mortality and the pollu-
tion of drinking water, a connection which has quite recently been
terribly emj^hasised in the case of Hamburg.

Such is the verdict with regard to cholern, and the same is true
of that other great water-borne disease, typhoid fever. But, unlike
cholera, this disease is disseminated in several other ways, and its
presence or absence in any locality may not, of necessity, have any
connection with the drinking water, as is strikingly shown by the
health statistics of Manchester.

There is no evidence whatever that, since the year 1869, when
typhoid fever appeared for the first time as a separate disease in the
liegistrar-General's reports, it has been conveyed by the water supply
of the metropolis. An inspection of the following diagram shows,
it is true, a greater proportional mortality during the period of
imperfect filtration than during the later period ; that is to say, from
1883, when the process began to be performed with uniform effi-
ciency ; but the plotting of a similar curve for the deaths by typhoid
in Manchester, shows that this disease arises from (jther causes than
polluted water, since the water supply of Manchester, derived as it

5G

Dr. Edward Franldaml

[Feb. 21,

is from mountain sources, is above all susiDicion of this kind. TLese
otlier causes have during the last ten years been much mitigated in
London by various sanitary improvements ; whilst, as shown in the
diagram (Fig. 1), there has been no corresponding mitigation in
Manchester. In this diagram the continuous dotted line shows the
mortality per 100,000 of population from typhoid in Manchester,
and the crossed broken line the death rate from the same disease in
London ; whilst the faint broken line represents the degree of tur-
bidity of river water delivered in London.

Although, very soon after the year 1856, all the water supplied
to the metropolis was obtained from sources much less exposed to
drainage pollution, it was still very carelessly filtered. Previous
to the year 1868, there are no records of the efficiency, or otherwise,

TTPK» M LONDON AND MANCHESTER CONTRASTED WITM TURBIDITY.

"^J'^Wi >^»;t^«HVH«7H8»'H«i*'«'i"^'»»H«7|««U'«\.. H«.|»Hm

1 1

^

'H

-^**--"-vf^T'---^--t

^i/ ■ / ' iJ !• '-n /

i 1 ' • V'

i ^

Fig. 1.

of the filtration of the metropolitan water supply derived from
rivers as distinguished from deep wells, the w^ater of which is per-
fectly clear without filtration.

It was in the year 1868 that I first began to examine the water
sup2)lied to the metroj)olis from rivers with reference to efficiency
of filtration. In that year, out of eighty-four samples examined,
seven were very turbid, eight turbid, and ten slightly turbid, so that
altogether no less than nearly 30 per cent, of the samj^les were those
of inefiiciently filtered water. The metropolitan water supply, then,
up to the year 1868, may be shortly described as derived, for many
years, from very impure sources, with either no filtration at all, or
with very inefficient filtration ; and afterwards, when the very impure
sources were abandoned, the supply was still often delivered in a
very inefficiently filtered condition. But, after the establishment of
monthly reports on the filtration of the river-derived supplies, the

1896.] on the Past, Present and Future Water Sajpply of London. 57

quality of these waters gradually improved, in this most important
res23ect, as is seen from the foregoing diagram.

These observations, graphically represented in the diagram, show
that at the time they were commenced the filtering operations were
carried on with great carelessness, and that this continued, though
to a less extent, down to the year 1883, since which time, and
especially since 1884, the efficiency of filtration of all the river
waters su]Dplied to the metroj^olis has left little to be desired.

What is it, then, that S8j)arates the past from the jDresent water
supply of London ? In the first place there is the change of source ;
I mean the change in position of the intakes of the several companies
drawing from the Thames and Lea, and the total abandonment of
the much polluted Eavensbourne by the Kent Water Company. So
long as the water supply was derived from the tidal reaches of the
Thames and Lea, receiving, as these reaches did, the drainao-e of
immense populations, the risk of infection from water-borne patho-
genic organisms could scarcely be otherwise than imminent ; for,
although we now know efficient filtration to be a perfect safeguard,
anything short of efficiency must be attended with risk in the presence
of such extreme pollution.

Nevertheless, the line of demarcation between the past and the
present water supply of the metropolis is, in my opinion, to be drawn
not when the intakes of the river companies were removed to positions
beyond the possibility of pollution by the _ drainage of London; but
at the time when efficient filtration was finally secured and ever since
maintained ; that is to say, in the year 1884.

The removal of turbidity by sand filtration, however, refers only
to suspended matter, but there are sometimes objectionable substances
in solution, of which organic matter is the most important. River
water and mountain water, even when efficiently filtered, contain
more organic matter than spring or deep-well water ; but this is
reduced in quantity by storage and especially by filtration ; although
it can, perhaps, never be brought up to the standard of organic purity
of spring and deep-well water.

The Present Water Sujpjply.

At present, London is supplied with water from four sources, the
Thames, the Lea, the New Kiver and deep wells. Of these, the deep
wells yield, as a rule, the purest water, requiring no filtration or treat-
ment of any kind before delivery for domestic use. The river waters

on the other hand, require some kind of treatment before delivery ;

storage and subsidence in reservoirs, and filtration. The water from
the Thames is abstracted at and above Hampton, far above the reach
of the tide and London drainage. The water from the Lea is taken
out at two 'points, viz. at Angel Road, near Chingford, by the East
London Water Company ; and above Hertford by the New River

58

Br. Edward Franhland

[Feb. 21,

Company, who convey it to Green Lanes by an open conduit 25 miles
long called the New Eiver Cut, in wbicli it is mixed with a consider-
able volume of spring and deep-well water.

All three river waters are affected by floods, and are, as raw
materials, of considerably different quality as regards organic purity,
as is seen in the diagram (Fig. 2). From these raw materials, by far
the largest volume of the metropolitan water supply is derived ; and
the chemical, or organic, purity of the water sent out to consumers
stands in direct relation to the organic purity of the raw material
used, as is seen from the diagrams (Figs. 3, 4 and 5), wLich show the
proportional amounts of organic elements in the raw and filtered
waters, and also the advantage of storage in excluding flood water.
Fig. 4 shows that floods in March and August were circumvented, but

PKWimONAL MKWT V ORCAMC CLStCMTil'
IN RAW MMTEfL

PROPORTIONAL AMOUNT OF ORGANIC ELEMENTS
IN THAMES WATER.

jm.

Ftk

am

^

J\

B95

JUC

JM.T

W

an

on

jf

m

—

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.-*'

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fta

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89^

i

M.1

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xn

OCT

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xc

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s

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Fig. 2.

Fig. 3.

not in November. The numbers in the margins of the diagrams
express the proportional amount of organic elements, that in the Kent
company's water during the nine years ending December 1876, being
taken as unity, as is depicted in the diagram (Fig. 5).

Hitherto I have spoken of chemical purity, or comparative freedom
from organic matter only ; but the spread of diseases, such as cholera
and typhoid fever, through the agency of drinking water, has no con-
nection whatever with the chemical or organic purity of the water.
These diseases are propagated by living organisms of extreme
minuteness, to which the names hacilli, bacteria and microbes have
been given ; and here comes the important question, how, if at all,
does filtration secure immunity from these water-borne diseases ?

To Dr. Koch, of Berlin, we are indebted for the answer to this

1896.] on the Past, Present and Future Water Sup2)l2j of London. 59

question. By his discovery of a means of isolating and counting tlie
number of bacteria, or bacilli, or microbes, and their spores in a given
volume of water, we were for the first time put into possession of a

PROPORTIOMAL AMOUNT OF ORGANIC OlMENTS
IN RAW LEA AND EAST LONOCW COMPAKlYlS WATER.

7-0
6-0
5-0
4^
SO
20
\0

JAN

FEB

MAR

AP

.I8S

MAY

5

JUNE

JUIY

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OCT

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DEC

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v?.".?

'.^J

'^>..AS

.''AV^-'■

.-^y-'

Fig. 4.

method by which the condition of water as regards these living organ-
isms, before and after filtration, can be determined with quantitative
exactness. The enormous importance of this invention, which was

PR0P0Rtl(5RAL AMOUNT OF ORGANIC ILEIviENTS
IN NEW RIVER AND DEEFWELL WATERS.

1895

JAN FEB MAR AP MAY JVNE JULY AUC SEPT OCT NOV DEC.

xcnconRSucr

A

.... ^V-M^.e ,

. u/»rj^'

V

Fig. 5.

first made known and practised in England in 1882 by the late
Dr. Angus Smith, is evident when it is borne in mind that the living
organisms, harmful or harmless, contained in water arc of such

60 Br. Edward FranMand [Feb. 21,

extreme mimiteness as, practically, to defy detection by ordinary
microscopical examination. But, although the microscope cannot
detect with certainty single bacteria or their spores, even the naked
eye can easily discern towns or colonies consisting of thousands or
even millions of such inhabitants.

Dr. Koch's method accomplishes at once two things : it isolates,
in the first place, each individual microbe or germ ; and secondly,
l^laces it in conditions favourable for its multiplication, which takes
place with such amazing rapidity that, even in a few hours, or at
most in two or three days, each organism will have created around
itself a visible colony of innumerable members ; a town, in fact, com-
parable to London itself for population.

By operating upon a known volume of the water under in-
vestigation, such as a cubic centimetre for instance, the number of
separate organit>ms or their spores, in a given volume of the water,
can thus be determined.

The following is the method now adopted in carrying out Koch's
process for the investigation of drinking water : —

1. Preparation of the nutritive medium.

2. Sterilisation of the medium.

3. Collection of the sample of water in a vacuous tube to be
hermetically sealed immediately afterwards.

4. Transport of the sample to the bacteriological laboratory.

5. Mixture of a known volume of the water sample with the
nutrient medium.

6. Casting of the mixture into a solid plate.

7. Incubation of the solid plate.

8. Counting of the colonies (suitable time for the colonies to
develop being given as shown in diagrams, Figs. 6, 7, 8 and 9).

Fig. 6 shows a gelatine culture of unfiltered Thames water placed
on a ruled surface to assist counting ; whilst Figs. 7, 8 and 9 illus-
trate the gradual development of the colonies in a gelatine culture of
y|-Q of a cubic centimetre of unfiltered Lea water collected at the
East London Company's intake on January 13, 1896. Fig. 7 shows
the condition of the colonies on the third day ; Fig. 8 the further
development on the fourth day ; and Fig. 9 the condition of the
colonies on the fifth day, when many colonies are mingled together
and counting is no longer possible.

9. Examination of separate colonies, or rather of the individual
members, under the microscope.

Sometimes the cultivations are made upon a plate of the substance
called agar, which resembles isinglass, and bears a temperature of
blood heat without melting (Fig. 10). There is a very remarkable
colony on this plate, showing an apjDarently organised city, with
suburbs stretching far into the country, and containing many millions
of inhabitants.

In order to ascertain the eflect of filtration upon the bacterial
quality of the water, it is absolutely necessary that the sample should

Fifi. 6.

Fig. 7.

Fig. 8.

Fig. 9.

Fig. 10.

Fig. 11.

1896.] on the Past, Present and Future Water Supply of London. 61

be taken immediately after it has passed through the filters ; for
if it be obtained from the delivery mains in town, that is to say,
after the water has passed through many miles of pipes, the rapid
multiplication of these organisms, excejjt in very cold weather, is
such that a water which contains only a single living organism
per cc, as it issues from the filter, may contain 100 or 1000 in the
same volume when, after several hours, it arrives on the consumers*
premises. Fig. 11 shows isolated bacteria, enormously magnified,
taken from one of the towns or colonies. The scale at the foot of
this figure represents thousandths of an inch.

Now what is the effect of sand filtration as carried out by the
various water companies supplying London, upon the living matter
contained in the raw river water ? It is simply astounding — water
which, when poured upon sand filters, contains thousands of bacteria
per c.c. — for a single droj) of Thames water sometimes contains
nearly 3000 sej^arate organisms — comes out from those filters with
50, 30, 10, or even less of these organisms per c.c. ; or the number
of microbes in a single drop is reduced to two or even to zero.

Eather less than one-tenth of the total volume of water supplied
to London is derived by the Kent Water Company from deep wells
in the chalk. As it issues from the porous rock into the fissures and
headings of these wells, this water is, in all probability, absolutely
sterile ; but, by the time it has been pumped up to the surface, it
usually contains a certain number, though small, of microbes.
Thus, during the year 1892 it contained on the average 6 per c.c. ;
in 1893, 13 ; in 1894, 15 ; and in 1895, 8.

The diagram (Fig. 12) shows, graphically, the bacterial improve-
ment of the river water by filtration during the j^ear 1894. In this
diagram, the black squares and white centres represent the relative
numbers of microbes in the unfiltered and filtered waters respec-
tively.

Thus, although the deep-well water has, from a bacterial point of
view, a decided advantage, the filtered river waters are not very far
behind ; and there is every reason to believe that with the improve-
ments which are now being carried out by the various river-water
companies, the Kent company's water will before long be run very
hard by the other supplies.

By the examination of the water as it issues from the filters, the
utmost freedom from microbes, or maximum degree of sterility, of
each sample is recorded. This utmost freedom from bacterial life,
after all sources of contamination have been passed, is obviously the
most important moment in the history of the water ; for the smaller
the number of microbes found in a given volume at that moment, the
less is the probability of pathogenic or harmful organisms being
present ; and although the non-pathogenic may afterwards multiply
indefinitely, this is of no consequence in the primary absence of the
pathogenic ; but it is only fair, in describing the character of the
present water supply of London, to say that not a single pathogenio

62 Dr. Edward Franldand [Feb. 21,

organism has ever been discovered, even in the imfiltered water as it
enters the intakes of the various companies, although these organisms
have been carefully sought for. It is sometimes even said that the
non-pathogenic organisms found in water may be beneficial to man,
but this idea is not borne out by their entire absence from the food
which nature provides for young animals. Milk is absolutely sterile
in its normal condition.

As it is at present impracticable to obtain water, uniformly at
least, free from microbes, it is desirable to adopt some standard of
bacterial purity ; and 100 microbes per c.c. has been fixed upon by

MICROBES IN RAW AND FILTERED THAMES
WATER 1894.

fEBRUARY MARCH APRIL

JUNE JULY AUGUST SEPTeMBER

october november december m£aw

Fig. 12.

Dr. Koch and mj'pclf as the maximum number allowable in potable
water. This standard is very rarely infringed by the London water
companies ; whilst I have every reason to hope that, in the near
future, now that special attention is directed to bacterial filtration, it
will not be approached within 50 per cent.

This hope is based, not only upon my own observations, but also
upon the exhaustive and exceedingly important investigations carried
out at the Lawrence Experiment IStation by the State Board of Health
of Massachusetts, under the direction of Mr. George W. Fuller, the
official biologist to the Board. More than six years have already
been spent in the prosecution of these American experiments, and
many thousands of samples of water have been submitted to bacterial
cultivation.

The Massachusetts experimental filters were worked at rates up to

1896.] on the Past, Present and Future Water Supply of London. 63

three million gallons per acre daily, which renders the results avail-
able for application to public water supplies ; indeed, none of the water
delivered in London is filtered at so rapid a rate as this. It was
found that, at these rates, all the disease-producing germs which were
intentionally, and in large numbers, added to the un filtered water,
were substantially removed. The filters were so constructed and
arranged as to allow direct comparison of the bacterial purification of
water under different rates of filtration — with sand of different degrees
of fineness, with diff'erent depths of the same sand, and with intermit-
tent and continuous filtration.

The actual efficiency of these filters was also tested by the appli-
cation of the bacillus of typhoid fever. During the earlier portions
of the year 1893 very large numbers of these bacilli and other sj^ecies
were applied in single doses to the several filters at different times,
and the effluent was examined four times daily for several days after-
wards. The results so obtained give a thoroughly trustworthy test of
the degree of bacterial purification effected by each of the experi-
mental filters, and these are the data which have been largely used by
the Massachusetts State Board of Health in deducing the rules which
they consider ought to be observed in water filtration.

Among the subjects investigated by means of these experimental
filters were : —

1. The effect upon bacterial purification of the rate of filtration,

2. The effect of size of sand grains upon bacterial purification.

3. The effect of depth of material upon bacterial purification.

4. The effect of scraping the filters upon bacterial purification.

These important experiments and my own bacterioscopic examina-
tions of the London waters, continued for four years, lead to the
following conclusions : —

1. The rate of filtration, between half a million and three million
gallons per acre per day, exercises, practically, no effect on the bacte-
rial purity of the filtered water. It is w^orthy of note that the rates
of filtration practised by the several water companies drawing their
supplies from the Thames and Lea, are as follows : — Chelsea Com-
pany, 1,830,000; West Middlesex, 1,359,072; Southwark Company,
1,568,160 ; Grand Junction Company, 1,986,336 ; Lambeth Company,
1,477,688 ; New River Company, 1,881,792; and East London Com-
pany, 1,393,920. Hence not one of the London companies filters at
the rate of two million gallons per acre per day, at which rate in the
Massachusetts filters, 99 • 9 per cent, of the microbes present in the
raw water were removed.

2. The effect of the size of sand grains is very considerable.
Thus, by the use of a finer sand than that employed by the Chelsea
Company, the West Middlesex Company is able, with much less
storage, to attain an equal degree of bacterial efficiency.

3. The depth of saud between the limits of one and five feet exer-
cises no practical effect on bacterial purity, when the rate of filtration
is kept within the limits just specified. Thus the New River Company,

64 Dr. Edward FranMand [Feb. 21,

with 1*8 foot of sand on the filters, compares favourably with the
Chelsea Company, the sand on whose filters is more than twice that
depth. Placed in the order of thickness of sand on their filters, the
following table shows that the metropolitan companies range as
follows : — Chelsea, Lambeth, West Middlesex, South wark. East
London, Grand Junction and New River. Placed iD the order of
efficient bacterial filtration, they range as follows : — Chelsea and
West Middlesex equal. New River, Lambeth, East London, South-
wark and Grand Junction.

Thiceness of Sand on Filters.

Chelsea 4'0 feet.

Lambeth 2-8 ,.

West Middlesex 2-G „

South wark 2-5 „

East London 2*0 „

Grand Juuction 1'^ „

New Kiver 1*8 „

Order of Bacterial Efficiency.

("Chelsea.

\West Middlesex.

New Eiver.

Lambeth.

East London.
South wark.
Grand Junction

4. When there is such an accumulation of deposit on the surface
of the sand filter that, for practical purposes, sufficient water cannot
be made to pass through it, the surface of the filter has to be scraped,
that is to say, the mud and about half an inch of the sand are re-
moved from the surface. After this operation, there is sometimes an
increase in the number of bacteria in the filtered water, and it is
noticed that the increase is greater in shallow than in deep filters,
and with high than with low rates of filtration ; and there is no
doubt that the efi'ect of scraping is considerably magnified when
coarser descriptions of sand are employed, as is the case in the
filters of the London water companies. I should like, therefore, to
impress upon the engineers of these companies the desirability of
using finer sands than are at present employed.

Influence of the Bacterial Condition of the Raio Biver Water
upon that of the Filtered Effluent.

I have found that the number of bacteria in a given volume of
filtered water is often, though not invariably, influenced by the number
contained in the raw water supplying the filter ; and from this point
of view, therefore, the bacterial condition of the raw river water used
in the metropolis is of no inconsiderable importance.

1896.] on the Past, Present and Fatiire Water Supply of London. C5

Since May 1892, I have been making monthly determinations of
the number of microbes capable of developing on a gelatine plate in a
given volume of Thames water collected at the intakes of the metro-
politan water companies at Hampton ; and the number has varied
during this time between 631 and 5(3,630 per c.c, the highest numbers
having, as a rule, been found in winter, or when the temperature of
the water was low, and the lowest in summer, or when the temperature
was high.

Now, besides temperature, there are two other conditions, to either
of which this difference may be attributed, viz. sunshine and rainfall ;
and I have endeavoured, by a series of graphic representations, to
disentangle these possible influences from each other, by placing the
results of the microbe determinations in juxtaposition with (1) the
temperature of the water at the time the samples were taken; (2) the
number of hours of sunshine on the day and up to the hour when the
sample was drawn, and on the two preceding days ; and (3) the flow
of the Thames over Teddington Weir on the same day, expressed
in millions of gallons per twenty-four hours. And, although the
graphic representations are confined to the Thames, the conditions
affecting bacterial life in this river are doubtless equally potent in
other rivers and streams.

The samples for microbe cultivation were collected at about nine
inches below the surface of the water, in partially exhausted and
sealed glass tubes, the ends of which, when the tubes were lowered
to the required depths, were broken off by an ingenious contrivance
devised by my assistant, Mr. Burgess. On being withdrawn from the
river, the tubes were immediately hermetically sealed and packed
in ice for conveyance to my laboratory, where the cultivation was
always commenced within four hours of the time of collection.

For the records of sunshine I am indebted to the kindness of
Mr. James S. Jordan, of Staines, and for gaugings of the TJiames at
Teddington Weir, to Mr. C. J. More, the Engineer to the Thames
Conservancy Board.

The graphic representation of these collateral observations affords
definite evidence as to which of the three conditions, temperature,
sunshine and flow of the river, has the predominant influence upon
bacterial life in the water. The first diagram (Fig. 13) compares the
number of microbes per c.c. with the temperature of the water at
the time the sample was taken. The horizontal lines express the
numbers of microbes and the temperature, while the vertical lines
denote the months when the samples were taken. For obvious
reasons, the horizontal lines expressing the numbers of microbes
and temperatures, are numbered in opposite directions.

The diagram shows that although coincidence between a higli
number of microbes and a low temperature are not wanting, some
other condition entirely masks the efiect, if any, of temperature.

The next diagram (Fig. 14) institutes the comparison between the
number of microbes and the hours of sunshine to which the water
Vol. XV. (No. 90.) p

(j6

Dr. Edward Franhland

[Feb. 21,

has been exposed. The diagram is constructed on the same lines as
the first.

It is evident, therefore, from this comparison that, as in the case
of temperature, there is some other condition which entirely overbears
the influence of sunlight in the destruction of microbes in the river
water. This condition is the amount of rainfall higher up the river,
or, in other words, the volume of water flowing along the river bed,
as is seen from the comparison represented in the next diagram
(Fig. 15).

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This diagram shows very conclusively that the volume of water
flowing in the Thames is the paramount influence determining the
number of microbes. It compares the volume of water in the river,
gauged at Teddington Weir, with the microbes found in the raw
Thames water at Hampton on the same day. In this diagram, the
numbers representing the flow of the river in millions of gallons per
day and the number of microbes per c.c. in the water, both run from
the bottom of the diagram upwards.

1896.] on the Past, Present and Future Water Supply of London. 67

Comparing the curves in tlie diagram, it is seen that, with a
few exceptions, a remarkably close relation is maintained between
them.

The only exception of any importance to the rule that the number
of microbes varies directly with the flow of the river, occurring
during the thirty-two months through which these observations were
continued, happened in November 1892, when the flow increased
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November, whilst the microbes actually diminished in number from
2216 to 1868 per cc. Neither the sunshine nor the temperature
records of these two months, however, afford any explanation of this
anomalous result : for there was a good deal of sunshine in October
before the collection of the sample, and the temperature was higher ;
whilst in November no ray of sunshine reached the Thames during
the three days preceding the taking of the sample, and the tempera-
ture was nearly 4° C. lower than in the preceding month. I have

f2

68

Dr. Edivard Franhland

[Feb. 21,

ascertained, however, that the Thames basin had been [twice very
thoroughly washed out by heavy floods shortly before the time when
the November sample was taken, and this affords a satisfactory ex-
planation of the anomalous result yielded by this sample.

These comparisons therefore demonstrate that the number of
microbes in Thames water depends directly upon the rate of
flow of the river, or, in other words, on the rainfall, and but
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or a high or low temperature; and they are confirmed by' the con-
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Fig. 16.)

With regard to the eff'ect of sunshine upon bacterial life, the
interesting observations of Dr. Marshall "Ward leave no doubt that
sunlight is a powerful germicide ; still, it is obvious that its potency
in this respect must be greatly dimini sbed, if not entirely annulled,
when the solar rays have passed throu gh a stratum of water, of even

189G.] on the Past, Present and Future Water Supphj of London. 69

comparatively small thickness, before they reach the living organisms.
By a series of ingeniously devised experiments, Mr. Burgess has
demonstrated the correctness of this view.

A sterile bottle, about half filled with Thames water, was violently
agitated for five minutes to insure equal distribution of the organisms.
Immediately afterwards, a number of sterile glass tubes were partially
filled with this water and sealed hermetically. Three of these tubes
were immediately packed in ice, and the remainder were attached in
duplicate at definite distances apart to a light wire frame which was
then suspended vertically
in the river. The experi-
ments were made near
the Grand Junction Com-
pany's intake, at a place
favourable for the sun's
rays to fall on the river
without any obstruction.

The river was, at the
time, in a very clear con-
dition and contained but
little suspended matter,
whilst the day was fine,
although clouds obscured
the sun occasionally.
The tubes were exposed
to light in the river for

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4i hours, from 10.30 a.m.
toSp.M. onMayl5, 1895.
At the end of this time
they were packed in ice
for transport to my labo-
ratory, where the cultivation was started immediately. The colonies
were counted on the fourth day, and yielded the results given in the
following table : —

No. of colonies
per c.c.

Thames water packed in ice immediately after collection
„ „ alter exposure to sunlight for ij hours at

surface of river

„ „ after exposure to sunlight for 4| hours at

6 in. below surface of river

„ „ after exposure to sunlight for 4J hours at

1 ft. below surface of river

„ „ after exposure to sunlight for 4| hours at

2 ft. below surface of river

„ „ after exposure to sunlight for 4| hours at

3 ft. below surface of river

2127
1140
1940
2150
2430
2440

These experiments show that on May 15 the germicidal effect
sunlight on Thames microbes was 7iil at depths of 1 foot and

of sunlight on

70 Dr. Edivard FranUand [Feb. 21,

upwards from the Burface of the comparatively clear water. It cannot,
therefore, excite surprise that the effect of sunshine upon bacterial
life in the great mass of Thames water should be nearly if not
quite imperceptible. We have thus ascertained that sunlight can
only^kill the germs or microbes near the surface of the water, whilst
those at any depth for the most part escape destruction.

On the other hand the enormous effect of floods in augmenting
the number of microbes can hardly surprise us; for when a great
body of water has flowed over the banks of the river, which are at
other times dry and exposed, carrying along with it countless im-
purities— an effect common both to the main stream and its tributaries
— the Thames basin is, as it were, on every such occasion, thoroughly
washed out, and it is only to be expected that the number of microbes
in the water should be enormously increased, as is found to be the

The Water Supply of the Future,

In view of the rapid increase of the population of London, fears
have, from time to time, been entertained that the water supply from
the Thames basin, that is to say, from the rivers Thames and Lea
supplemented by water from springs and deep wells within the basin
itself, would soon be insufficient in quantity ; whilst the quality of
the water taken from the rivers has, up to a comparatively recent
date, been considered unsatisfactory. On these grounds various
schemes have, from time to time, been brought forward for the
supply of the metropolis from other river basins — from the Wye, the
8evern, the river basins of North Wales, and of the lake districts
of Cumberland and Westmoreland. It is worthy of note, however,
that all the Koyal Commissions have arrived unanimously at the
conclusion, that the quantity of water obtainable from the Thames
basin is so ample as to render the necessity of going elsewhere a
very remote contingency.

I shall now endeavour to put very shortly before you the facts
which, in my opinion, prove that, both as regards quantity and
quality, the Thames basin will, for a very long time to come, afford
an abundant supply for the metropolis. There is, indeed, no river
basin in Great Britain which aftbrds such an abundant supply of
excellent water as that available in the Thames basin.

Besides that which flows directly into the river, this water is
contained in the chalk, oolite and lower greensand, which are the
best water-bearing strata in the kingdom. From these strata it
issues in copious springs of unsurpassed organic purity. I have
personally inspected every spring of importance in the Thames basin,
and have analysed samples of the water. The results, in a very
condensed form, are recorded in the following table : —

1896.] on the Past, Present and Future Water Supphj of London. 71

Spring and Deep-Well Waters in the Thames Basin.

Chalk.

Results of Analysis, in

Oolite.
Average of

Lower
Greensand.

Parts per 100,000.

21 samples.

Average of

Springs.

Wells.

5 samples.

Average of
8 samples.

Average of
36 samples.

Total saline matters . .

27-34

18^25

30-14

37-45

Organic carbon . .

•035

•032

•041

•052

Organic nitrogen . .

•012

•006

•010

•019

Hardness be tore boiling

22-5

10^5

25-3

28-0

Hardness after boiling

5-5

3-6

4-9

6-5

Twenty-one samples of oolitic spring water were analysed, and
every one of these was of even greater organic purity tban the water
delivered by the Kent company, which I have always regarded as the
standard of organic purity to be aimed at in all other water-works.

Five springs issuing from the lower greensand were examined,
and again every one of these was of even greater purity, organically,
than the Kent company's water ; whilst they were, on the average,
only one-third as hard. Forty-six samples of water from the chalk
were chemically examined, and these also contained but the merest
traces of organic matter.

All these samples from the chalk were derived from sources
where the water-bearing stratum is free from a covering of London
clay ; but as soon as the chalk dips beneath the London tertiary sands
and clay, the quality of the water undergoes a remarkable alteration.
The total solids in solution are greatly incrensed in amount, whilst
the hardness is much mitigated, owing to the replacement of bicar-
bonate of lime by bicarbonate of soda. These waters are also of
high organic purity ; but, as the quantity is very limited, it is useless
to dwell upon them. They supply the Trafalgar Square fountains
and the London breweries, and we can well aflord to leave them to be
converted into beer. For dietetic purposes, there is no better water
in the kingdom than the underground water of the Thames basin.
For sentimental reasons, I should like to see it conveyed to the works
of the various companies in special conduits ; but we have seen that,
on hygienic grounds, it may safely be allowed to flow down the bed of
the Thames, if it be afterwards efficiently filtered.

So much for quality, now as to quantity. The basins of the
Thames and Lea include an area of upwards of five thousand square
miles. Of this, rather more than one-half, including the oolitic,
cretaceous, and portions of the tertiary formations, is covered by a
porous soil upon a permeable water-bearing stratum. The remainder
is occupied by the Oxford, Kimmeridge, Gault and London clays,
being thus covered by a clay soil upon a stiff and impervious subsoil.

72 Dr. Edward FranMand [Feb. 21,

The annual rainfall of the district is estimated on an average at
28 inches. The rivulets and streams of the Thames basin are formed
and pursue their course on the clay land. There are no streams on
the chalk. That which falls upon this porous stratum and does not
evaporate, sinks, mostly where it alights, and heaps itself up in the
water-bearing stratum below, until the latter can hold no more. The
water then escapes as springs at the lowest available points. Innu-
merable examples of these springs occur all round the edge of the
Thames basin, and at various points within it. Thus, from the chalk
they are ejected at the lip of the gault, and in the oolitic area, by
the fuller's earth below it, or by the Oxford clay geologically above it.
According to the gaugings of the engineer of the Thames
Conservancy Board there passed over Teddington Weir in 1892,
387,000 millions of gallons, equal to an average flow of 1060 millions
of gallons daily. In the following year, 1893, there passed over
Teddington Weir an aggregate of 324,227 millions of gallons, or a
daily average of 888 millions of gallons, the average for the two years
being 974 millions of gallous ; and this number does not include the
120, or 130, millions of gallons daily abstracted by the six London
water companies who draw their supplies, wholly or partially, from
the Thames.

Thus, in round numbers, we may say that after the present wants
of London have been supplied from this river, there is a daily average
of a thousand millions of gallons to spare. Surely it is not too
violent an assumption to make, that the enterimsing engineers of
this country can find the means of abstracting and storing, for the
necessary time, one-fourth of this volume.

As regards the quality of ihis stored water, all my examinations
of the effect of storage upon the chemical, and especially upon the
bacterial quality, point to the conclusion that it would be excellent.
Indeed, the bacterial improvement of river water by storage, for
even a few days, is beyond all expectation, as is proved by the ac-
companying photographic diagrams. Thus the storage of Thames
water by the Chelsea company for only thirteen days, reduces the
number of microbes to less than one-eighth of the original amount,
as is proved by the photographic diagrams. Figs. 17 and 18. Fig. 17
shows the result of a gelatine plate culture of -}q of a cubic centi-
metre of unfiltered Thames water collected on January 10, 1896.
It gave 11,560 colonies per c.c. ; whilst Fig. 18 shows the result of
a similar cultivation of ^L of a c.c. of Thames water collected on the
same day, after storage for thirteen days. It gave only 1360 colonies
per c.c. The storage of the Eiver Lea water for fifteen days, by the
East London company, reduces the number from 9240 to 1860 per
c.c, or to one-fifth (see diagrams Figs. 19 and 20) ; and lastly, the
water of the New River Cut, containing on the average 4270 microbes
per c.c, contained after storage for less than five days only 1810 (see
diagrams, Figs. 21 and 22, in which the results of the cultivation of
Jq of a c.c. of the water before and after storage are contrasted).

Fig. 17.

Fia. 18.

Fig. 19.

FiCx. 20.

Fig. 21,

Fig. 22.

1896.] on the Past, Present and Future Water Supply of London. 73

These samples were collected on December 11, 1895.* The reduc-
tion here being not so great, partly on account of the shorter storage,
but chiefly because the New Eiver Cut, above the point at which the
samples were taken, is itself a storage reservoir containing many
days' supply. Indeed, quietness in a subsidence reservoir is, very
curiously, far more fatal to bacterial life in river-water than the
most violent agitation in contact with atmospheric air : for the
microbes which are sent into the river above the falls of Niagara
by the city of Buffalo seem to take little or no harm from that
tremendous leap and turmoil of waters ; whilst they very soon almost
entirely disappear in Lake Ontario.

Thus it is not too much to expect that storage for, say a couple of
months, would reduce the number of microbes in Thames flood water
down to nearly the minimum ever found in that river in dry weather ;
whilst, by avoiding the first rush of each flood, a gcod chemical
quality could also be secured. There is therefore, I think, a fair
prospect that the quantity of water derivable from the Thames at
Hampton could be increased from its present amount (120 millions of
gallons per diem) to 370 millions.

Again, in the River Lea, although here the necessary data for
exact calculation are wanting, it may be assumed that the present
supply of 54 millions of gallons could be increased by the storage of
flood water to 100 millions of gallons per day. To these volumes
must be added the amount of deep-well water which is obtainable
from those parts of the Thames basin which lie below Teddington
Lock, and in the Lea basin below Lea Bridge, and which was esti-
mated by the last Royal Commission appointed to inquire into the
water supply of the metropolis, at rather more than 67^ millions of
gallons.

Thus we get the grand total of 537J millions of gallons per day
of excellent water obtainable within the Thames basin, the quality
of which can be gradually improved, if it be considered necessary, by
pumping from the water-bearing strata above Teddington and Lea
Bridge respectively, instead of taking the total supj)ly from the
open rivers above these points. Such a volume of water would
scarcely be required for the supply of the whole water area of London
at the end of fifty years from the present time, even supposing the
population to go on increasing at the same rate as it did in tlie decade
1881-91, which is an assumption scarcely likely to be verified.

In conclusion, I have shown that the Thames basin can furnish
an ample supply for fifty or more years to come, whilst the quality of
the spring and deep-well waters and the filtered river water would

* All the bacteriological illustratious used in this discourse were photographs
taken by Mr. Burgess from tJie actual growtlis on the gelatine plates; and
my be.-t thanks are due to him for the veiy skilful execution of this difificidt and
delicate work, involving, as it di^l in many cases, the "svalching of the cultivations
from hour to hour.

74 Dr. FranTcland on Water Snpply of London. [Feb. 21,

be unimpeachable, To secure these benefits for the future, storage
must be gradually provided for 11,500 millions of gallons of water,
judiciously selected in the Thames valley, and a proportionate
volume in the basin of the Lea ; whilst filtration must be carried to
its utmost perfection by the use of finer sand than is at present
employed, and by the maintenance of a uniform rate during the
twenty-four hours.

There is nothing heroic in laying pipes along the banks of the
Thames, or even in making reservoirs in the Thames basin. They
do not appeal to the imagination, like that colossal work, the bring-
ing of water to Birmingham from the mountains of Wales ; and there
is little in such a scheme to recommend it to the mind of the
ambitious engineers of to-day. Nevertheless, by means of storage, by
utilising springs, by sinking deep wells, and by such comparatively
simple means, there is, in my opinion, every reason to congratulate
ourselves that, for half a century at least, we have at our doors, so to
speak, an ample supply of water which, for palatability, wholesome-
ness, and general excellence will not be surpassed by any supply in
the world.

[E. F.]

189 1.] Marine Organisms. 75

WEEKLY EVENING MEETING,

Friday, February 28, 1896.

Edward Frankland, Esq. D.C.L. LL.D. F.E.S. Yice-President,

in the Chair.

John Mdrray, Esq. LL.D. Ph.D. D.Sc. F.R.S.

Marine Organisms and the Conditions of their Environment.

Thk ocean may be divided into two great biological regions, viz. the
siiperj&cial region, including the waters between the surface and a
depth of about 100 fathoms, and the deep-sea region extending from
the 100 fathoms line down to the greatest depths. The superficial
region may be subdivided into two proviuces, viz. the shallow-water or
neritic province around the land masses where the depth is less than
100 fathoms, and the pelagic province, embracing the superficial
waters of the ocean basins outside the 100 fathoms line ; these two
provinces contrast sharply as regards physical conditions, which are
of great variety in the neritic province, and very uniform over wide
areas in the pelagic province.

Temperature is a more important factor in determining the
distribution of marine organisms, mostly cold-blooded, than in the
case of terrestrial species, mostly warm-blooded and air-breathing
animals, the distribution of which depends rather upon topographical
features than upon climatic conditions.

A map was exhibited showing the range of temperature in
the surface waters of the ocean all over the world, and indicated
northern and a southern circunipolar areas with a low temperature
and small range (under 10° F.), and an almost circumtropical area
with a similar small range but high temperature ; in temperate
regions the range is greater, the areas of greatest range (over 40°
F.) being found off the eastern coasts of North America and of Asia
and south of the Cape, due to the mixture of currents from different
sources, which sometimes causes the destruction of enormous numbers
of marine invertebrates and fishes.

The pelagic tropical waters of the ocean teem with various forms
of life, of which probably 70 to 80 per cent, function as plants,
converting, under the influence of sunlight, the inorganic constituents
of sea- water into organic compounds, thus forming the original source
of food of marine animals both at the surface and at the bottom of
the sea.

The number of species living in the pelagic waters of the tropics

76 Dr. John Murray [Feb. 28,

may greatly exceed the number in polar waters, where, on the other
hand, there is often a great development of individuals, so that there
is probably a greater bulk of organic matter in the cold polar
waters than in the warm tropical waters. The rate of animal meta-
bolism is slower at a low than at a high temperature, and organisms
inhabiting tropical waters probably pass through their life-history
much more rapidly than similar organisms living in polar regions.
Carbonate-of-lime-secreting organisms are most abundant in the
warm tropical waters, decreasing in numbers towards the polar
regions, and it has been shown that the jDrecipitation of carbonate of
lime from solution in sea-water takes place much more rapidly at a
high temperature. The pelagic larvae of bottom-living species are
always present in the warm surface waters of the tropics, sometimes
growing to an enormous size ; but they are absent from the cold polar
waters and in the deep sea, where the majority of the bottom -living
species have a direct development.

The Arctic fauna and flora, both at the surface and at the bottom,
resemble the Antarctic fauna and flora, and a large number of
identical and closely-related species are recorded from the two polar
areas, though quite unknown in the intervening tropical zone.

The boundary line between the deep-sea region and the neritic
province is marked out by what has been called the " mud-line,"
where the minute organic and inorganic particles derived from the
land and surface waters find a resting place upon the bottom, or
serve as food for enormous numbers of Crustacea, which in their turn
are the prey of fishes and the higher animals ; this mud-line, in fact,
appears to be the great feeding-ground in the ocean, and its average
depth is about 100 fatlioms along the borders of the great ocean basins.

The majority of deep-sea species are mud eaters ; some are of
gigantic size ; some are armed with peculiar tactile, prehensile, and
alluring organs ; some are totally blind, whilst others have large eyes
and are provided with a kind of dark lantern for the emission of
phosphorescent light. The deep-sea fauna does not represent the
remnants of very ancient faunas, but has rather been the result of
migrations from the region of the mud-line in relatively recent
geological times.

The Challenger investigations show that species are most abundant
in the shallow waters near land, decreasing in numbers with increasing
depth, and especially with increasing distance from continental land.*
This is true as a general rule, especially of tropical waters, but in
polar regions there are indications of a more abundant fauna in
depths of 50 to 150 fathoms than in shallower water under 50
fathoms. "I"

* See ' Challenger Keports,' " A Summary of the Scientific Kesults," by
John Murray, pp. 1430-1436, 1895.

t See Murray, " On the Deep and Shallow-Water Marine Fauna of the
Kergiielen Kegion of the Great Southern Ocean," Trans. Koy. Soc. Edin.
vol. xxxviii. p. 343, 1896.

1896.] on Marine Organisms, &c. 11

The various points touclaed upon regarding the distribution of
marine organisms, might be explained on the hypothesis that in early
geological times there was a nearly uniform high temperature over the
whole surface of the globe, and a nearly uniformly distributed fauna
and flora ; and that with the gradual cooling at the poles, species with
pelagic larvse were killed out or forced to migrate towards the tropics,
while the great majority of the species which were able to survive in
the polar areas were those inhabiting the mud-line. The uniform
physical conditions here referred to might be explained by adopting
the views of Blandet * as to the greater size and nebulous character
of the sun in the earlier ages of the earth's history.
[J- M.]

* Bull. Soc. geol. de France, ser. 2, t. xxv. p. 777, 1868.

78 General Monthly Meeting. [March 2,

GENERAL MONTHLY MEETING,

Monday, March 2, 1896.

SiK James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Herbert John AUcroft, Esq.

R. Lawrence Andrews, Esq.

Ernest Clarke, M.D. B.S. F.R.C.S.

Mayo Collier, Esq. M.B. F.R.C.S.

Henry Ernest Bry, Esq.

Mrs. Francis Gaskell,

Edward Gimingham, Esq.

Alexander Glegg, Esq.

Sir Cameron Gull, Bart. M.P.

Miss Catherine Imray,

Charles W. Keighley, Esq.

Edward Law, M.D. M.R.C.S.

Charles Letts, Esq.

Montefiore Micholls, Esq. M.A.

Reginald Empson Middleton, Esq. M.Inst.C.E.

Alexander Paine, M.D. B.S.

George H. Sykes, Esq. M.A. M.Inst.C.E.

William Lloyd Wise, Esq. J.P.

were elected Members of the Royal Institution.

The following Arrangements for the Lectures after Easter were
announced : —

Professor James Sdlly, M.A. LL.D. of University College, London. — Three
Lectures on Child-Study and Education ; on Tuesdays, April 14, 21, 28.

C. Vernon Boys, Esq. F.R.S. A.R.S.M. ilf.B.L— Three Lectures on Ripples
IN Air and on Water; on Tuesdays, May 5, 12, 19.

Professor T. G. Bonney, D.Sc. LL.D. F.R.S.— Two Lectures on The Build-
ing AND Sculpture of Western Europe (TheTyndall Lectures); on Tuesdays,
May 26, June 2.

Professor Dewar, M.A. LL.D. F.R.S. Jf.i^.I.— Three Lectures on Recent
Chemical Progress ; on Thursdays, April 16, 23, 30.

W. GowLAND, Esq. F.C.S. F.S.A. (late of the Imperial Japanese Mint). — Three
Lectures on The Art of Working Metals in Japan ; on Thursdays. May 7,
14, 21.

Robert Munro, M.D. M.A. (Secretary of the Society of Antiquaries of Scot-
land).— Two Lectures on Lake Dwellings ; on Thursdays, May 28, June 4.

Professor W. B, hicHMOND, R.A. — Three Lectures on The Vault of the
SixTiNE Chapel ; on Saturdays, April 18, 25, May 2.

F. CoRDER, Esq. (Curator, Royal Academy of Music). — Three Lectures on
Three Emotional Composers — Berlioz, Wagner, Liszt : with Musical Illus-
trations ; on Saturdays, May 9, 16, 23.

Dr. E. a. Wallis Budge, M.A. Litt.D. F.S.A. (Keeper of the Egyptian and
Assyrian Antiquities, British Museum). — Two Lectures on The Moral and
Religious Literature of Ancient Egypt ; on Saturdays, May 30, June 6.

1896.1

General Montldy Meeting.

79

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

8vo. 1896.
1896.

FROM

Accademia dei Lincei, Beale, Roma — Classe di Scienze Fisiche, Matematiche e
Naturali. Atti, Serie Quinta: Reudiconti. 2" Semestre, Vol. V. Fasc. 2.
8vo. 1896.
Astronomical Society^ Boyal — Monthly Notices, Vol. LVI. No. 3. 8vo. 1896.
British Architects, Royal Institute of — Journal, 3rd Series, Vol. III. No. 7. 4to.

1896.
British Astronomical Association — Journal, Vol. VI. No. 4. 8vo. 1896.
Cadbury, Richard, Esq. (the Author) — Cocoa ; all about it. By " Historicus." 8vo.

1896.
Cambridge Philosophical Society — Proceedings, Vol. IX. No 1.
Camera Club — Journal for February, 1896. 8vo.
Chemical Industry, Society of — Journal, Vol. XV. No. 1. 8vo.
Chemical Society — Journal tor February, 1896. 8vo.

Proceedings, Nos. 159, 160. 8vo. 1895-96.
Cracovie, V Academic des Sciences — Bulletin, 1896, No. 1. 8vo.
Editors — American Journal of Science for February, 1896. 8vo.

Analyst for February, 1896. 8vo.

Anthony's Photographic Bulletin for February, 1896. 8vo.

Astro-Physical Journal for February, 1896. 8vo,

Athenaeum for February, 1896. 4to.

Bimetallist for February, 1896.

Brewers' Journal for February, 1896. 8vo.

Chemical News for February, 1896. 4to.

Cliemist and Druggist for February, 1896. 8vo.

Electrical Engineer for February, 1896. fol.

Electrical Engineering for February, 1896. 8vo. /rs.^

Electrical Review for February, 1896. 8vo. /^

Electric Plant for February, 1896. 4to.

Electricity for February, 1896. 8vo.

Engineer for February, 1896. fol.

Engineering for February, 1896. fol. V"^^

Engineering Review for February, 1896. 8vo. ^

Homoeopathic Review for February, 1896. 8vo.

Horological Journal for February, 1896. 8vo.

Industiies and Iron for February, 1896. fol.

Invention for February, 1896.

Ironmongery for February, 1896. 4to.

Law Journal for February, 1896. 8vo.

Lightning for February, 1896. 8vo.

London Technical Education Gazette for February, 1896. 8vo.

Machinery Market for February, 1896. 8vo.

>lature for February, 1896. 4to.

Nuovo Cimento, Oct.-Dec. 1895. 8vo.

Photographic News for February, 1 896. 8vo.

Science Sittings for February, 1896.

Scientific African for January, 1896. 8vo.

Scots Magazine for February, 1896. 8vo.

Technical World for February, 1896. 8vo.

Transport for February, 1896. fol.

Tropical Agriculturist for February, 1896.

Work for February, 1896. 8vo.

Zoophilist for February, 1896. 4to.
Electriccd Engineers, Institution o/— Journal, Vol. XXIV. No. 119. 8vo. 1896.
Florence, Biblioteca Nazionale Centrale — Bolletino, No. 243. 8vo. 1896.

80 General Monthly Meeting. [March 2,

Fournet, H. Esq. — The General Medical Council and Sight Testing. 8vo. 1896.
Franldin Institute— J ourn^il for February, 1896. 8vo.

Geographical Society, Eo?/aZ— Geographir-al Journal for February, 189f5. 8vo.
Geological Society— QueiYttrlj Journal, No. 205. 8vo. 1896.

Geological Literature added to the Society's Library during the year 1895.

8vo. 1896.
Harlem, Societe Hollandaise des Sciences — Archives Neerlandaises, Tome XXIX.

Livr. 4% 5e. 8vo. 1896.
Eeneage, Charles, Esq. {the Translator) — Austrian Procedure re Curatel, and

Habitual Drunkards in Austria and the Curatel Procedure. By Professor

Schlangenhausen. 8vo. 1896.
Imperial Institnte—lmiperia} Institute Journal for February, 1896.
Johns Hopkins University — American Chemical Journal, Vol. XVIII. No. 2. 8vo.

1896.
Manchester Steam Users' Association — Kitchen Boiler Explosions. 8vo. 1896.
Massachusetts Inditute of Technologij— Technology Quarterly and Proceedings of

the Society of Arts, Vol. VIII. No. 3. 8vo. 1895.
Mathieson and Sons, Messrs. F. C. (the Pahlishers)— Stock Excliange Values ; a

decadeof finance; 1885-95. By F. Van OSS. 8vo. 1895.
Indian Railwiiy Companies, 1896. By E. W. Montgomery. 8vo. 1896.
Mathiesnn's Monthly Mining Handbook. 1896. 8vo.
Odontoloqical Society of Great Britain — Transactions, Vol. XXVIII. No. 3. 8vo.

189K.
Pharmaceutical Society of Great Britain— Jomnal for February, 1 896. 8vo.
Phiisical Society— PTOceedings, Vol. XIV. Part 2. 8vo. 1896.
Richardson, Sir Benjamin Ward, M.D. F.R.S.— The Asclepiad, No. 4-1. 8vo.

1891-95.
Roijal Society of Er7m&urgf/i— Proceedings, Vol. XX. (pp. 481-546). 8vo. 1891-95.
Royal Society of London — Philosophical Transactions, Vol. CLXXXVI. A. Part 2 ;

Vol. CLXXXVII. A. Nos. 169, 170. 4to. 1896.
Catalogue of Scientific Papers, 1874-83, Vol. XI. 8vo. 1896.
Sanitary' Institute — Report on tlie Scientific Study of the Mental and Physical

Conditions of Childhood. 8vo. 1895.
Selborne Society — Nature Notes for February, 1896. 8vo.
Society of Antiquaries of London — Proceedings, Second Series, Vol. XV. Nos. 3, 4.

8vo. 1894-95.
Society of Arts — Journal for February, 1896. 8vo.
Sylvester, J. J. Esq. M.A. LL.D. F.R.S. {the Author)— 'Exercises in Latin Prose

and Verse.
United Service Institution, Royal— 3 ouvnal, No. 216. 8vo. 1896.
United States Department of Agriculture — Experiment Station Record, Vol. VI.

Nos. 6, 7 ; Vol. VII. Nos. 1, 2. 8vo. 1895.
Verein zur Beforderung des Gewerbjleisses in Preussen — Verhandlungen, 1896:

Heft 1. 4to. 1896.
Very, Frank W. Esq. (the Author) — Photometry of a Lunar Eclipse. 8vo. 1895.

1896.1 The Tunnel under the Thames at Black wall. 81

WEEKLY EVENING MEETING,
Friday March 6, 1896.

Sir Benjamin Baker, K.C.M.G. LL.D. F.R.S. M. Inst. C.E.

Manager, in the Chair.

Alexander R. Binnie, Esq. M. Inst. C.E. F.G.S. M.B.L

Chief Engineer L.C.C.

The Tunnel under the Thames at Blachvall.

The subject of this evening's discourse, the tunnel under the Thames
at Blackwall, at once defines and narrows it to an account of the
construction of a subaqueous tunnel ; and although I shall describe
the whole work, yet my remarks will be more particularly directed to
that part of the tunnel which is situate under the Thames, A tunnel
may be defined as a horizontal or inclined subterranean perforation
or boring, generally constructed for the accommodation of a roadway,
a railway, or a canal. It will be noticed that I use the word perfora-
tion or boring, by which I mean a subterranean excavation carried
out in a horizontal or inclined direction underground, either from its
two ends or from the bottoms of shafts sunk to the proper depth upon
its centre line. I make this definition lio prevent confusion with
another very similar class of work, to which I shall have to allude,
which is constructed by first sinking or digging a horizontal trench
to the required depth, in which the roadway is formed and arched
over, the excavation or trench afterwards being filled in above it.
This mode of construction is termed cut and cover work, and is the
way in which the sewers in our streets are generally built, and most
of our underground railways were carried out as cut and cover work.
In tunnelling, therefore, at the outset of our description, I wish
you to bear in mind that the work divides itself naturally into
two main portions : (1) the excavation, digging or blasting of the
material to be removed ; and (2) into lining or arching in the exca-
vation, so as to prevent the sides, top and bottom from foiling in or
being pressed upwards by the weight of the superincumbent earth
or rock. It will at once be noticed, therefore, that the mode of con-
structing any particular tunnel will difier very much according to
the nature of the material to be excavated, be it" rock, clay, gravel, or
quicksand, and that in construction the whole work will be rendered
much more costly and difficult if it has to be carried through £^round
Vol. XV. (No. 90.) g

82 Mr. Alexander E. Binnie [March 6,

highly charged with water ; and when, as in the case of the Blackwall
Tunnel, it has to be executed through gravel under a wide river like
the Thames, the cost, difficulty and dangers of the work approach
the limit of engineering skill to carry it successfully to completion.

It will be at once obvious that if the tunnel is of any considerable
size, and the soil to be excavated is of a soft nature such as clay, sand,
gravel, or the like, considerable difficulty will be experienced in
supporting the face, sides and top of the excavation, before the
lining is built into its place. If the work be of small dimensions it
is often called a heading, and its top is supported on cross timbers
resting on side props. Should it, however, be of larger size, the
timbering becomes much more complicated and costly, and requires
great skill in its design and management. When, between the
years 1818 and 1825, Sir Mark Isambard Brunei was thinking out
the mode of constructing the old Thames Tunnel between Rother-
hithe and Wapping, he designed several pieces of apparatus, which
he termed shields, to obviate the use of all the mass of timber
usually required. Some contrivance of this description became
necessary, for it was imperative that as far as possible, if settle-
ments or subsidences in the bed of the river were to be avoided,
no more material should be excavated than was just required to
receive the brickwork of the tunnel. Besides which, it is very pro-
blematical if the mode of timbering usually adopted would withstand
the varying strains to which it would be subjected under the varying
pressures due to the different depths of water at high and low tide.
The shield he ultimately adopted was a structure of iron, which could
be pushed forward in front of the work as it progressed, a model of
which stands on the table. It was so designed as to afford platforms
on which the men could work at different levels ; it afforded a means
of supporting the face and roof during excavation, and a place of
safety in the rear of the shield in which the brickwork of the tunnel
could be built up, and it could be pushed forward gradually in sections
by means of screw-jacks. I have now, I hope, made clear the general
subject, and must proceed to the particular work before us to-night.

Position of the tunnel. — During the past ninety years many pro-
posals have been made for crossing the Thames below London Bridge,
where the port of London, with its river, ships and docks, forms a
barrier to vehicular or pedestrian traffic between its opposite banks.
The first work of the kind attempted, but not completed, was Yazes'
tunnel at Limehouse, in 1805. We then have Brunei's tunnel, 1825
to 1841. Then the Tower Subway for foot passengers, 7 feet in
diameter, carried through the London clay, in 1869-70, by Messrs.
Barlow and Greathead. And finally, the late Metropolitan Board of
Works obtained an Act in 1887 to construct a tunnel under the
Thames at Blackwall, six miles from London Bridge. This tunnel
crosses the river IJ miles below Greenwich and 3 miles above Wool-
wich, and will bring these growing and populous places into direct
communication with Poplar and the East and West India Docks on

1896.] on the Tunnel under the Thames at Blackwall. 83

the north side of the Thames. The section of the tunnel shows
that at this point the river is 1200 feet in width and 46 feet in
depth at high water ; and borings revealed the fact that although
the London clay was present on both banks of the river, yet
that the tunnel must pass below it into the sands and clays of the
Woolwich series, and for a considerable distance through a bed of
gravel which apparently filled an older and deeper river bed. Not
only had the river to be passed under, but it will be noticed that it is
embanked, and that what were the old marshes on each side are below
the level of high water in the river. Further, it will be observed from
the section that the soil of these marshes, to a depth considerably
below that of low water in the river, consists of vegetable soil, peat,
sand and gravel, all of them highly charged with water. Under this
is the London clay with its base beds of impure limestone full of
fossils, and then the sands, clays, &c., of the Woolwich beds ; all these
beds were under the full pressure of water due to the varying tidal
level, and in their natural state so saturated were some of the beds of
sand as to convert them into quicksands.

But undoubtedly the most serious obstacle was the large deep bed
of coarse gravel with but little sand. This gravel was open and fully
saturated with the river water, and as the bottom of the tunnel was
to be 80 feet below high water it was certain that a pressure of about
35 lbs. on the square inch would have to be encountered. This,
however, was not the only difficulty, for it was clear that if the water
could find an easy entrance to, and flow amoug the gravel, air would
also as easily escape from it. It was obvious, therefore, from the
outset that the tunnel would have to be constructed under difficulties
never before contended with, either in the construction of Brunei's
tunnel at Kotherhithe or elsewhere. Moreover, it was evident that
no ordinary mode of tunnelling could be adopted, and that some
description of shield would be required. Also, from the difficulties
met with by Brunei at the much easier site at Rotherhithe, that some
more than ordinary measures would have to be resorted to to keep
out the inflow of water in passing under the river and through the
gravel bed above referred to. It was consequently determined to use
compressed air, as had been first suggested, in his patent of 1830, by
Admiral Lord Cochrane (Earl Dundonald), and which had been
successfully used under Lake Michigan and the Hudson River at
New York, as well as at the tunnel under the Saint Clair Eiver, and
on a portion of the City and South London Railway at Stockwell.
After consultation with Sir Benjamin Baker and Mr. Greathead, the
final design was determined upon, and the contract was let by the
London County Council to Messrs. S. Pearson and Son for 871,000Z.
early in 1891.

The whole work is 6200 feet in length ; the incline on the south
or Kent side of the river is on a gradient of 1 in 36 and has a run of
2408-6 feet ; the portion under the river for a distance of 1212 feet is
level, and the north or Middlesex incline has a gradient of 1 in 31 for

G 2

8J: Mr. Alexander B. Binnie [Marcli 6,

a lenfyth of 2579*6 feet. In other words, tlie inclined approaches
will not be so steep as parts of St. James's Street and Eegent Street,
and very mncb less so than the east side of Trafalgar Square opposite
Morley's Hotel ; they will, however, be about equal to that of the
Haymarket. The work may be divided into three portions : open
approaches with side walls ; cut and cover arched over with brickwork ;
and tunnel proper composed of cast-iron rings lined with concrete
and faced with white glazed tiles, all the other parts of the work
being faced with white glazed bricks.

The lengths of the various portions, including the shafts, are as
follows : —

Feet.

Open approach .. 1735

Cut and cover ]382

Cast-iron tunnel 3083

6200
or a total of a little over 1 mile.

To facilitate the work, so as to permit of altering its direction,
which it would be difficult to do by means of a long curve in a tunnel
of this description lined with cast iron, and to secure ventilation,
there are four shafts varying in depth from 75 to 98 feet, and having
an internal diameter of 48 feet.

The tunnel proper is circular in cross section, 27 feet outside
diameter, or 6 feet larger than that of St. Clair (the largest hitherto
constructed), built up of fourteen cast-iron segments and a key-piece ;
each complete ring of segments is 2 feet 6 inches in width. The
thickness of the cast iron is 2 inches, the flanges are 12 inches in
depth, measured from the outside, and each segment weighs about
one ton. The joints are brought to a true and even surface by
machine planing, and all are bolted to each other and to the adjacent
cast-iron rings by wrought-iron bolts and nuts. To ensure that the
cast-iron plates have a firm abutment upon and against the surround-
ing earth, there is a hole near the centre of each fitted with a screw
plug through which grout is forced as wdll be presently described.
Tiie internal edges of the flanges of the plates are recessed for a
depth of 2 inches, and after they are fixed in position and bolted
together this recess is filled and caulked with rust joint cement com-
posed of iron borings and sal-ammoniac. The space between the flanges
and for a distance of 4^ inches beyond in front is filled up solid
with Portland cement concrete faced with white glazed tiles, so that
the effective diameter of the tunnel is 24 feet 3 inches. Within this
the road of 16 feet, with two foot-paths each 3 feet IJ inches in width
is formed, resting on an arched subway 12 feet in width and 5 feet
6 inches in height for the reception of water pipes. There are also
proper drains for the road, and channels for smaller pipes for road
cleansing, &c. This road of 16 feet will be of the same Avidth as parts
of Little Queen Street, Holborn, and King Street, Westminster, and
of a greater width than parts of Drury Lane, Fetter lane. Upper and

1896.] on the Tunnel under the Thames at Blackwall. 85

Lower Thames Street, London Wall, Lombard Street and Thread-
needle Street, and as there will be no occasion for stopping at shops,
houses and street corners it should be ample for two lines of the
largest vehicles. Should the traffic, however, increase beyond the
capacity of the tunnel, land has been secured for the construction of
another and parallel line of tunnel. The road will be paved with
asphalt in the level portion under the river and with granite laid in
tar and pitch on the inclined approaches.

The whole work underground will be lighted by three rows of
incandescent 32 candle-j)ower electric lamps placed alternately
10 feet apart on the common centre line, no gas being admitted to
any portion of the tunnel. The cut and cover portions of the work
are formed of brickwork varying in thickness from 18 inches to
2 feet, this is covered with IJ inches of asphalt and backed with
2 feet of Portland cement concrete, giving a thickness at the thinnest
part of 3 feet 6 inches. Internally the cut and cover portions
will in all respects resemble that of the tunnel proper formed in
cast iron. The open approaches above referred to are flanked with
inclined retaining walls, faced with white glazed bricks, carrying
a high fence wall with stone coping. At each extremity the tunnel
will be approached through an arched gatew^ay supporting the lodcre-
keeper's house ; there will also be stairway access at the junction
of the open approach with the cut and cover, as well as sitairways
down one of the shafts on each side of the river. The shaft near
the river on the south side being in private property is domed
over and a ventilating chimney carried up from it ; the similar shaft
near the river on the north side is devoted to administrative and
working purposes such as pumping, elevating, lighting, &c. Each
shaft is 58 feet outside and 48 feet inside diameter and is formed as
it were of two skins of riveted wrought ironwork ; the two skins are
braced and held together by wrought-iron struts and ties, the space
between them being filled in solid with Portland cement concrete.
Near the lower extremity of each shaft its walls are perforated by
two openings 29 feet 4 inches in diameter. These openings are for
the purpose of forming junctions with the tunnel, and were tempo-
rarily closed during the time the shafts were being sunk by means of
large wrought-iron plugs. At a distance of 8 feet from the bottom
the inner skin is bent outwards to join the outer skin and together
form a comparatively sharp cutting edge. All the shafts will be lined,
when finished, with white glazed brickwork. The shafts were sunk in
the following manner. Having been built up to a considerable
height above the surface of the ground in the positions they were to
occupy, the earth, clay, sand, &c. were excavated within the circum-
ference of the shafts and from below the cutting edge, and as this
process of excavation proceeded, the shaft sank into the ground partly
by its own weight and in some cases assisted by additional weight
placed upon it. When the final level was reached the bottom for a
depth of 13 feet was filled in with concrete, in which, and attached to

86 Mr. Alexander B. Binnie [March 6,

the walls of the shaft, was fixed a water-tight wrought-iron floor. As
the junction between the tunnel and shafts nearest to the river had to
be made under compressed air, provision was made for fixing tempo-
rary air-tight floors at a level of a few feet above the crown of the
tunnel. These air-tight floors were held down by wrought-iron girders
12 feet and 4 feet in depth secured to the sides of the shafts so as to
prevent the floors from being blown upwards under an air pressure
of 4000 tons.

I think that I have now, in its main outlines, described the prin-
cipal features of the work, and must proceed to give some account of the
mode of its construction. In doing this, I shall have first to describe
the shield and then the mode of working it under compressed air. This
shield is a structure of steel, cylindrical in shape, 19 feet 6 inches in
length and 27 feet 8 inches outside diameter. It is stiflened by two cir-
cular partitions 3 feet apart, and its forward or working face, which
presses against the material to be excavated, is divided into twelve
pockets or cells, by three horizontal and three vertical partitions. It is
within these spaces, which are six feet in height, that the men work.
Between the two circular stiflening partitions are formed air-locks and
shoots for passing out the excavated material. Arranged round the
inner circumference of the shield and attached to it and the circular
partitions are disposed twenty-eight hydraulic rams 8 inches in
diameter, for the purpose of pressing or pushing the shield forward.
In the rear of the shield, or that portion of it which faces the
completed tunnel, is a space which is merely enclosed within the
outer skin of the shield ; this space is called the tail of the shield : it
always overlaps by 2 feet 6 inches, or one cast-iron ring, the last
completed portion of the tunnel, and within it are built up the various
rings of iron with which the tunnel is lined. Attached to the back
or rearward part of the two circular stiffening partitions and pro-
jecting into the tail of the shield are two hydraulic erectors for
placing the segments of the rings in position. There are two vertical
rams which cause a rackwork to move up or down in a vertical
direction. These racks gear into a pinion which carries an arm.
Consequently, the vertical motion of the rack causes the arm to move
through an arc of a little over 180°. This arm carries another ram
by which the arm can be lengthened or shortened as desired. In
working, the end of the arm can be attached to the lug or projection
cast on the centre of the inner side of each segment, where, by the
turning and lengthening motion of the arm, the segment can be
placed in any desired part of the ring. The shield, weighing about
250 tons, was built in an excavation at the top of shaft No. 4, and
when completed its ends were closed with timber to make it water-
tight and it was floated into shaft No. 4, which had been filled with
water. The water was then pumped out of the shaft, and as the water
fell the shield floating on its surface gradually descended until it
rested on the bottom.

As above described it will be noticed that the twelve working

1896.] on the Tunnel under the Thames at BlackwalL 87

cells or pockets are open in front, and the shield is so used in hard or
stiff ground, but in the gravel beds the working face has, except when
the excavation is in progress, to be very carefully closed with the
wrought-iron shutters secured with screws as shown on the section, the
mode of working which will be presently described.

Compressed Air. — We all know that air at the sea-level presses
with a force of from 14:| to 15 lbs. per square inch, and can support
a column of mercury of from 30 to 31 inches in height. We know
that it has bulk, for if we invert a tumbler in a basin of water there
will still be a space filled with air into which the water cannot enter.
If we try the experiment we shall find that this air space will be
larger or smaller depending on the depth to which we immerse the
tumbler, consequently we see that air is an elastic body. By proj)erly
constructed air-compressing pumps, we can force air down into a
diving bell until all the water is expelled from it and the surplus
escapes through the open bottom of the bell. If we then measure the
amount of compression of the confined air, we shall find it equivalent
to the weight of a column of water equal to the area of the open
bottom of the bell and as high as the depth of the water.

It having been decided to use compressed air to keep out the
water from the tunnel during its construction, the question arose, what,
having regard to the health of workers, was the highest pressure
which could be adopted with safety, as on this clearly depended the
greatest depth to which the bottom of the tunnel and shafts could be
carried. In going into the matter, it was evident that it would not
be a case of one or two men occasionally going down to perform
some temporary work, but that gangs of from sixty to eighty men
would have to be kept at work night and day, for many months, con-
sequently a safe maximum had to be arrived at. In places in America,
men had worked under a pressure of 48 lbs. per square inch above
the atmospheric pressure, that is, 68 lbs. absolute ; at Stockwell on
the City and South London Kail way it was about 15 lbs. ; and
after many inquiries 35 lbs. per square inch or 50 lbs. absolute was
determined upon.

I have stated it in this way because in addition to whatever
artificial pressure we may apply, it must be borne in mind that we
always have the initial pressure of the atmosphere to work under,
which is about 15 lbs. per square inch. In what follows, however, I
shall speak only of the artificial pressure, leaving it to be understood
that we always have the natural pressure in addition. If the extreme
safe pressure be fixed at 35 lbs. per square inch, it follows that the
bottom of the tunnel must not go lower than 80 feet below high
water mark. This being settled, the next point to be decided was how
large could we make a circular tunnel so that it did not project
upwards through the gravel into the river. In other words, what was
the safe minimum amount of cover that could be allowed over the top
of the tunnel and between it and the river bed. This, after much
consideration, was provisionally fixed at 6 feet, but in construction,

88 Mr. Alexander B. Binnie [March 6,

the least depth was somewhat less. It was due to these considera-
tions coniDled with the widths of the busy streets above spoken of
and the size of the largest vehicles, such as furniture vans, &c.,
that the outside diameter was fixed at 27 feet.

Having now described the work and some of the main conditions
under which it had to be constructed, you will have noticed that to
keep out the water, compressed air is employed, and that to drive the
shield forward, hydraulic pressure is used, the macliinery for which
requires a few words of description. For the purpose of air com-
pression, six steam engines and air pumps are provided, and these are
situate on the south bank of the river near shafts Nos. 3 and 4. They
have a united capacity of 1500 horse-power, but only about 1000 to
1200 horse-power are used continuously as one engine has to be kept
idle in case of accident or breakdown. When working at 1000 to
1200 horse-power, these engines and pumps force into the tunnel
about 8000 cubic feet of air per minute, or 17 tons weight per hour.
The air from these various engines is first conducted into a wrought-
iron reservoir 28 feet in length and 7 feet in diameter, formed like a
steam boiler. The first effect of compression, it is needless to say, is
to raise the temperature of the air very much, in fact to about 90° or
100° F., consequently before it can be conducted into the tunnel it has
to be cooled by passing it through a series of smaller tubes surrounded
with cold water like the surface condenser of a steam engine. From
the coolers it is led in pipes down shaft No. 4 and along the tunnel
through the air-tight bulkhead, presently to be dealt with, to the
working face.

In describing the shield, I mentioned that it weighs about 250
tons, and that it has to be thrust forward as the excavation is com-
pleted by the twenty-eight hydraulic rams which abut or press upon
the last completed ring of the tunnel. To produce the necessary
total pressure of about 2800 to 3000 tons an hydraulic pressure up to
2| tons per square inch has to be maintained. This is developed by
two hydraulic engines of 70 horse-power, and transmitted in pipes
down shaft No. 4, along the tunnel and through the air-tight bulk-
head to the working face.

I have previously spoken of a certain structure which I have called
the air-tight bulkhead. This I must now describe. It is clear that if
we are to use the compressed air in the tunnel to press against the
working face and keep out the water, it must in some way be con-
fined, or it would rush out backwards and escape up the shaft. To
confine the air in the tunnel, temporary air-tight walls or partitions
called bulkheads are built across it. As these have to bear an
outward thrust or bursting pressure of about 1000 tons, they are
formed of massive walls 12 feet in thickness, built of brickwork in
Portland cement. It is, however, obvious that they must not be
solid but must have means of access formed to allow of entrance
and exit both for men and materials. To permit of this access
air-locks have to be formed through the bulkhead. These are for

1896.J on the Tunnel under the Thames at BlacJcwall. 89

a similar purpose, and act in a like manner, to the locks on a canal.
la one case we have to overcome a difference of water-level, and
in the other a difference of pressure between that of the ordinary
atmosphere outside and the working pressure produced by the
air-compressing engines inside the bulkhead, be it 20, 26, or
30 lbs. per square inch. The air-locks consist of wrought-iron
cylinders, 15 feet in length and 6 feet in diameter, securely built
into the brickwork of the bulkhead. There are two of these air-
locks at the level of the road near the bottom, each provided with two
doors 5 feet by 4 feet fixed at either end of the lock and opening
inwards towards the pressure inside. There is another but smaller
air-lock placed near the top of the tunnel to permit of escape in case
of accident. Supposing you wish to enter, the outer door is open,
but the inner one closed and pressed against by a force of say 30 tons.
It is clear that you cannot open this door until you have equalised
the pressure on both sides of it. To do this you enter the lock and
close the outer door to prevent the escape of air, after which a tap or
cock is opened which permits the compressed air from inside to rush
into the lock until the pressure within it is equal to that on the inner
side of the balkhead. As soon as this equality is established the
inner door can be opened and you step into the working pressure.

Visit to tie Tunnel. — In attempting to describe the work of
construction, I do not think I can do better than in imagination to
conduct you over the work during a visit of inspection. It is first
necessary for ladies and gentlemen alike to put on waterproof boots,
woollen overalls and caps so as to keep dry and clean ; these are in
readiness for the purpose at the tunnel. Descending by the steps at
the end of the open approach on the south side of the river, we pass
for over 300 yards through the finished cut and cover portion of the
work and have an opportunity of noticing what will be the general
size and appearance of the interior of the tunnel, and that, although
it is all below high-water mark and its lower end beneath the level
of the bed of the river, yet it is quite dry and dusty under foot. On
reaching the bottom of shaft No. 4 the large steam pumps for lifting
out the water during construction will be noticed, for it must be
remembered that although the work when finished will be quite dry
and water-tight, yet during construction, even with the use of com-
pressed air, a large volume of water enters the work and has to be
got rid of. This mainly arises from the fact that the difference in
hydrostatic external pressure due to the 27 feet in height of the
shield amounts to about 12 lbs. per square inch. So that if the full
air pressure due to the external hydrostatic pressure at the bottom
of the shield and working face were always kept up, it would escape
in too large volumes from the top of the excavation and through
any porous soil. In fact, to prevent this too rapid escape of air
through the gravel, as well as to weight the material over the
shield, where the covering was least in thickness above it, clay
was deposited in the bed of the river for a width of 150 feet,

90 Mr. Alexander B. Binnie [March 6,

and from 10 to 15 feet in depth immediately over the part of the
tunnel under construction. While the tunnel was being formed
beneath the river there was always a very large escape of air which
boiled up through the water, and also came up in some places in-
land at a distance of 800 feet from the working face. Notwithstand-
ing all the precautions taken the air pressure on two occasions blew
up the bottom of the river, and once the surface water rose to a height
of 25 feet over a diameter of 50 feet. Any water therefore which
enters the tunnel between the working face and the air-tight bulk-
head, is forced out through pipes which extend from the working face
through the air-tight bulkhead to the bottom of shaft No. 4, the supe-
rior air pressure within the working part of the tunnel being used
for the purpose ; and from the bottom of shaft No. 4 it is raised by
steam pumps to the surface. Passing from the bottom of shaft No. 4
down the incline to shaft No. 3, the visitor may observe the cast-
iron rings of which the tunnel is built up quite uncovered as the inner
lining of concrete has not yet been inserted. It will be noticed that
the work is lighted by means of incandescent electric lamps which give
sufficient light to see that, as fixed, the plates are quite water-tight
and, but for appearance sake, require no internal lining. After
passing the bottom of shaft No. 3, which is domed over, we enter on
the portion of the tunnel below the river, and most probably soon after
hear a loud rumbling roaring noise. This is caused by the escape of
the compressed air from one of the air-locks as some men or materials
are being locked out. Arriving at the air-tight bulkhead we enter
the lock, close the outer door, and turn on the compressed air which
enters from the working space beyond the bulkhead. The effect of
so doing is at once apparent, for the noise of the inrushing air is as
loud as that of the steam escaping from some large steam boiler, and
quite drowns the voice and renders hearing impossible. At the same
time every one feels a more or less acute pain in the ears caused by
the increased pressure of the air on the outer surface of the drum of
the ear ; this can in most cases be removed by equalising the
pressure through the Eustachian tubes which communicate with the
middle ear ; this is effected by swallowing, and blowing into the nose
when it is pinched with the fingers, but if the pain becomes and
continues very acute the person suffering should at once leave the
air-lock.

As the air in the lock becomes more compressed the temperature
rises rapidly ; this is due to the compression and only lasts while in
the lock, for as soon as equalisation is established and the inner door
is opened and you step into the working space you find the tempera-
ture falls to about 60° to 65° F. I am often asked what it feels like
in compressed air ; this I think must in all cases be a personal matter.
But summing up the result of my many weekly visits to the tunnel
during the past two years, I should say that I feel no difference from
that when under the ordinary atmospheric pressure. There is a very
slight feeling of exhilaration if the pressure is over 20 lbs. per square

1896.] on the Tunnel under the Thames at Blackwall. 91

inch, probably caused by the larger amount of oxygen absorbed by
the lungs ; every one appears to speak with a nasal intonation, you
cannot whistle, and the skin acts more freely than at the same tem-
perature under normal conditions. I should here note that no one
becomes ill from the effects of compressed air while under its pressure,
the baneful effects, if experienced at all, usually show themselves on
coming out of it. But I have arrived at the conclusion that among
otherwise healthy persons some can and some cannot withstand air
pressure, and 1 have had the pleasure of conducting many persons
over the works, from little girls of thirteen up to gentlemen of over
seventy years of age, who have not felt the least ill effects from com-
pressed air.

Passing on to the shield and the working face we see the two main
operations in progress: (1) excavating; and (2) erecting the cast-
iron rings of the tunnel.

Excavation. — As to the excavation, the mode of conducting it
depends on the kind of ground being pushed through. If it be hard
or stiff enough to stand with a vertical face when pressed against by
the various partitions of the shield, the men simj^ly dig or pick it
away in front for a few inches or a foot or two, passing the excavated
material out to the stage behind the shield, from which it is tipped
into wagons and removed. After a sufficient amount has been cleared
and loosened in front of the shield, the latter is, by the hydraulic jacks,
pressed forward, it may be a few inches or perhaps 2 feet 6 inches,
the distance depending on the nature of the ground. Each ring dis-
places 54 cubic yards, and progress has varied from 1 foot up to
10 feet a day. If, however, the material be gravel the progress is
very slow as this material will not remain vertical when dug into,
but runs down as fast as it is excavated. Besides which, so rapid is
the escape of air that if precautions were not taken it would pass out
in dangerous quantities. To obviate this and to support the face,
the front of each pocket or working face is closed with three wrought-
iron shutters pressed forward by powerful screws, and all the joints
luted with clay. In these circumstances the excavation is made either
by raking out the gravel through holes in the shutters, or by drawing
them back one at a time, digging out a small portion and then screw-
ing forward the shutter again. When all the shutters have been
screwed forward the shield is advanced, and as the screws are so
arranged as to allow of their slipping through the nuts attached to
the shield, the result is that it moves forward past the shutters which
remain in the positions into which they have been screwed. It need
not be said that this is slow and tedious work requiring great skill
and patience.

Erecting the Mings. — After the shield has been pressed forward so
as to leave a clear space in the tail of 2 feet 6 inches, the erectors are
brought into work, and, as before described, the various segments and
the key-piece erected. It will be noticed that as the tail of the
shield overlaps the last finished ring of plates it leaves an annular

92 Mr. Alexander B. Binnie [March 6,

vacuity, 4 inches in width, between the back of the plates and the
natural ground. This space is made solid by the injection of grout
under pneumatic pressure by means of the contrivance patented by
Mr. Greathead. This consists of a closed horizontal cylinder in
which lime or cement can be mixed to the consistency of thick cream
by a horizontal spindle with arms which pass through it. The upper
side is furnished with a pipe through which air pressure can be applied
to the surface of the grout, and from the lower side the grout is con-
veyed in another pipe to the holes in the plates through which it is
forced by the air pressure.

To provide against accidents, two precautions are adopted in case
of an inrush of water : one is an elevated temporary wooden gangway
or path, extending from the shield to the upper escape air-lock in the
air-tight bulkhead, the other is a fixed curtain of wrought iron which
descends to the semi-diameter of the tunnel, so that in case of an
irruption of water it would not fill the entire tunnel, but a certain
portion of compressed air would be trapped between the curtain and
the air-lock, and so form a kind of elongated diving bell.

Having now viewed all that is to be seen in compressed air, we
return to the air-lock for the purpose of passing out. This is in
some respects difterent from passing in, and is an operation requiring
some little time and caution, as the removal of the artificial air
pressure and the return to normal conditions is more than equivalent
to an ascent beyond the tops of the highest mountains on the earth,
as the artificial pressure may be 30 lbs. per square inch, all of which
has to be removed before we return to the normal 15 lbs. As to
sensation, no difficulties about the treatment of the ears is experienced
as the compressed air in the middle ear gradually and naturally dis-
charges itself with a not unpleasant crackling sound. Owing, however,
to the expansion of the air in the lock, the temperature falls rapidly,
so much so that the invisible aqueous vapour contained in the air is
deposited as a thick damp fog, and a chill is experienced ; beyond
this there is nothing particular to notice. From the tunnel we ascend
the shaft No. 4 and in the cabin at the top take a cup of hot coifee,
which slight stimulant is sufficient to restore the system to its usual
condition.

I am frequently asked if we have found any objects of interest or
antiquity in our various excavations. But as most of our work has
been through the tertiary beds of the London clay and Woolwich
series, nothing but the fossils peculiar to these formations have been
met with. On the table will be found specimens of the base bed of
the London clay, and of the conglomerate bed which lies just below
it. These two formations have also been met with on other works,
as at Abbey Mills and the Beckton Gas-works. There is also a
specimen of the shelly clay of the Woolwich series. In the super-
ficial gravel, part of an elephant's tusk was found on the south shore
of the river; a similar tusk was also found on another work in the
gravel beds near Abbey Mills at Stratford. On the north side of the

1896.] on the Tunnel under the Thames at Blachwall. 93

river at Blackwall Cross, about 8 feet below the street level, a human
skeleton was found, and as a stake was also found which appeared
to have been driven through the body at the time of burial, in
all probability the remains were those of some poor suicide who
had been interred with all the superstitious rites of our ancestors.
Beyond the above I do not think anything of interest has been
discovered.

Experience of Compressed Air. — In some previous works carried
out under compressed air, oiuch illness and some deaths have occurred.
The symptoms of the more frequent though not serious illnesses are
violent and acute pains of a neuralgic kind, generally in the limbs,
and which are experienced at the time of, or shortly after coming out
of compressed air. The more serious, and in some instances fatal
cases took the form of vertigo and paralysis, usually of the legs.
Consequently at an early period the London County Council adopted
every precaution ; they obtained Parliamentary power to compensate
persons permanently or temporarily injured, and they appointed a
resident medical officer. Dr. Snell, whose duty it was not only to
attend to cases of illness, but to see that none but healthy men were
allowed on the work, and to keep a watch on all the men employed
in compressed air, besides which he was instructed to note from a
medical point of view, and make a study of, all the conditions of the
problem. We have now been at work under compressed air for about
two years, we have had no deaths and only one case of permanent
injury (a case of Menier's disease, due to rupture of the semicircular
canal of the inner ear). It had often been noticed, on previous works,
that illness was most prevalent when the work progressed most
slowly, and that it decreased as the progress became more rapid.
We now believe, from our experience at Blackwall, that this was due
to the larger amount of air pumj)ed down during rapid work. With-
out for a moment wishing in any way to forestall Dr. Snell, who
will no doubt make public the result of his observations at the
proper time, we believe that up to a pressure of from 30 lbs. to
35 lbs. per square inch, healthy men can work with almost an entire
absence of illness, if a sufficient amount of compressed air, say 8000
to 9000 cubic feet per hour, be supplied to each man.

Conclusion. — In drawing this discourse to a conclusion, I feel
that I have but very imperfectly performed the duty which I have
undertaken. We have now completed all the work on the south side,
the river has been passed, and we are working up the incline near
shaft No. 1, and if all goes well we hope to comj^lete the whole by
about March next year. In contemplating the work at Blackwall it
is interesting to compare the progress in engineering work during
the past fifty years. Brunei's tunnel was about the same length
as the |)()rtion under the river at Blackwall, and it took about nine
years, with many long pauses, to complete ; the portion of the Black-
wall tunnel under the river between shafts 2 and 3 was tunnelled in
about thirteen months. The cost of Brunei's tunnel was at the rate

94 The Tunnel under the Thames at Blackmail. [March 6,

of about 1300Z. per yard, while that at Blackwall averages 550Z. per
yard. This is most gratifying after the gloomy forebodings by
which we were met before we commenced the work. It was at that
time predicted, and I was personally warned by members of my own
profession, that if we succeeded at all, it would only be by chance,
and at the cost of much suffering and death. The success that has
attended us is due to all who have been engaged upon the work, and
particularly to the skill and untiring energy of three gentlemen,
the two resident engineers, Messrs. Hay and Fitzmaurice, and to
Mr. Moir, who acts as engineer for, and representative of the con-
tractors, Messrs. Pearson and Son. But in claiming for ourselves at
the present time credit for the success that has attended our efforts,
we must not forget the honour due to those who have preceded us.
No one can in a large and complicated modern work such as I
have been describing, claim for himself the exclusive credit for the
whole or any important part of it. We have been using a shield,
under compressed air, jDUshed forward by hydraulic power, and at
once the names of Bramah, Brunei and Dundonald remind us that
we are largely indebted to them. Much has been said and written
about the shield we have used, and some names have been associated
with its design. I wish it clearly to be understood that no one has
any right to do so, as it is a combination of all the good points in
many previous efforts in the same direction. But if to any one is due
more credit than to another it is to that remarkable genius the elder
Brunei, who, although he was himself unable to use his own invention,
saw clearly how the work could be best accomplished, and as far back
as 1818 took out a patent for a shield and mode of constructing
subaqueous tunnels. As described in and shown on the drawings
attached to his specification of 1818, we find a cylindrical wrought-
iron shield, divided into working cells or pockets, the tail of which
overlapped a tunnel some 20 feet in diameter, which tunnel was
formed of cast-iron rings, and the whole shield was to be ju'essed
forward by hydraulic jacks. From Dundonald's specification of 1830
we get the mode of making a tunnel under compressed air ; and to
Bramah is due, in a great measure, the invention of the hydraulic
press. Therefore in this as in so many other of our works, it is
seen that we owe a deep debt of gratitude to our predecessors for the
success we have attained.

[A. E. B.]

1896.] The Theory of the Ludicrous. 95

WEEKLY EVENING MEETING,

Friday, March 13, 1896.

George Matthey, Esq. F.E.S. Vice-President, in the Chair.

William Samuel Lilly, Esq. M.A. Hon. Fellow of Peterhouse,
Cambridge.

The Theory of the Ludicrous.

The feelings aroused by the perception of the Beautiful, the
Sublime and the Ludicrous, are referred by modern writers on
psychology to the domain of what Kant has taught us to call the
Esthetic. It seems to be pretty generally allowed that the Beau-
tiful attracts without repelling, and affects us with unmingled
pleasure in the free exercise of our cognitive faculties ; while the
feeling of the Sublime is mixed of pleasure and pain, involving,
as it does, fear and awe as well as admiration. Eegarding the
Ludicrous there is much less agreement, and few modern psycholo-
gists appear to have made it the subject of profound or far-reaching
studies. That is one reason why I have chosen it as my topic to-
night. Now in dealing with the Ludicrous, the first thing to be
remembered is its vast extent.

Let us look a little at the varieties of it, as that will help us,
perhaps, to the theory of which we are in quest. I have thought
that it would be well to catalogue them — a thing, so far as I am
aware, not previously attempted. My catalogue, which reduces them
to twenty-one headings, is as follows : —

1. Humour.

2. Wit.

3. Irony.

4. Satire.

5. Sarcasm.

6. Parody.

7. Bathos.

8. Bulls.

9. Puns.

10. Banter,

11. Caricature.

12. Buffoonery.

13. Mimicry.

14. The Comical.

15. The Farcical.

16. The Burlesque.

17. The Grotesque.

18. Alliteration.

19. Conundrums.

20. Charades.

21. Practical Joking:.

Now I am far from asserting that this catalogue is exhaustive,
although I have taken a great deal of pains with it, and cannot call
to mind any instance of the Ludicrous that may not be brought under
one or another of its twenty-one headings, which, I may observe, are,
so to speak, mere finger-posts for guidance in a vast and ill-explored

96 BIr. William Samuel Lilly [March 18,

country. Most of them seem so plain and intelligible as to require
no discussion. We all know, for instance, what Puns, Charades and
Conundrums are. We all know, or may know with a little reflection,
what is properly meant by Sarcasm, Banter, Caricature. But there
are four varieties of the Ludicrous which seem to present special
difficulties. And upon these I must offer a few remarks.

First then in this catalogue of mine stands Humour, which seems
to me beyond question the highest manifestation of the Ludicrous.
And I do not think we can have a better account of Humour than
one given by an admirable writer to whom some of us had the
pleasure of listening in this place yesterday afternoon : " That spirit
of playing with the vain world and all that therein is, familiar to
Socrates, which is always more or less discernible in the highest
natures." * The question is often asked, What is the dilierence
between Humour and Wit ? A great many different answers have
been given, one of the least satisfactory of them, as it seems to me,
being Sidney Smith's in the ' Lectures on Moral Philosophy ' which
he delivered here ninety years ago. I shall return to that presently.
For myself I would say, borrowing from the German a distinction
now pretty familiar to cultivated people throughout the world, that
Wit specially implies Understanding — Verstand — while Humour has
most in common with Eeason — Vernunft — in which there is always
an element, latent it may be, of tragedy. The greatest humorist in
Shakespeare is " the melancJioly Jacques." And here I am reminded
of some words of that most accomplished critic, the late Mr. Walter
Pater. In his Essay on Charles Lamb he characterises Wit as " that
unreal and transitory mirth which is as the crackling of thorns under
a pot," and Humour as " the laughter which blends with tears, and
even with the subtleties of the imaginaticm, and which, in its most
exquisite motives is one with pity — the laughter of the Comedies of
Shakespeare, hardly less expressive than his moods of seriousness or
solemnity of that deeply stirred soul of sympathy in him, as flowing
from which both tears and laughter are alike genuine and con-
tagious." This is, I think, true as regards Humour, although it
hardly does justice to Wit. What Sidney Smith says in his ' Lectures '
about Wit and Humour appears to me most unsatisfactory, which is
the more surprising since he himself was doubtless one of the wittiest
of his generation. Humour, he tells us, consists in " discovering in-
congruity between ideas which excite surprise, and surprise alone."
It is a surjjrising proposition ; but at all events it becomes intelligible
when we see what it is that he means by Humour. He gives three
instances : A young officer of eighteen years of age coming into
company in full uniform, but with a wig on his head, such as was
worn at the beginning of this century by grave and respectable
clergymen advanced in years ; a corpulent and respectable tradesman,

* Dr. William Barry, the author of ' The New Antigone,' in an Essay on
Carlyle.

1896.] on the Theory of the Ludicrous. 97

with habiliments somewhat ostentatious, sliding down gently into the
mud, and dedecorating a pea-green coat ; and the overturning of a
very large dinner table with all the dinner upon it. But these do
not appear to me to be examples of Humour at all. My old friend
Dr. Kennedy, for many years Eegius Professor of Greek at Cam-
bridge, a very dignified and correct person, was dining in the hall of
one of the colleges of that University upon some festive occasion,
and found himself next to a well-known joker, whose facetiousness,
never very refined, grew coarser and coarser as the banquet proceeded,
while the Doctor's face grew glummer and glummer. At last the
funny man said, " You seem to have no taste for humour. Professor."
" Sir," replied the Doctor, much in wrath, " I have a taste for
humour, but I have no taste for low buffoonery." Well, what Sidney
Smith gives as his first instance of Humour appears to me — to use
Dr. Kennedy's expression — low buffoonery ; his other two instances
I should refer to the category of the Comical. As little can I accept
Sidney Smith's account of Wit. " It discovers," he tells us, " real
relations that are not apparent between ideas exciting surprise, and
surprise only." Surely this will not stand. Consider, for example,
the lines of Pope — Hazlitt judged them the finest piece of Wit he
knew — on the Lord Mayor's Show, and the Lord Mayor's Poet
Laureate : —

" Now night descending the proud show is o'er,
But lives in Settle's numbers one day more."

What discovery is there here of real but not apparent relations
between ideas producing surprise, and surprise only ? Or take
the lines — far wittier I think than these — of Pope's Epistle to
Dr. Arbuthnot. He is speaking of certain bad poets : —

" He who still wanting, though he lives on theft,
Steals much, spends little, yet has nothing left ;
And he who now to sense, now nonsense leaning.
Means not, but blunders round about a meaning ;
And he whose fustian 's so sublimely bad,
It is not poetry but prose run mad."

Surely the Wit here does not lend itself to Sidney Smith's explana-
tion. But as I have ventured thus to criticise this gifted man's
definition of Wit, perhaps I ought to offer for your criticism a
definition of my own. I should say, then, that Wit consists in the
discovery of incongruities in the province of the understanding
( Verstand), the distinctive element which it leaves out being the
element of reason {Vernunft).

I am equally dissatisfied with Sidney Smith's account of another

variety of the Ludicrous, namely, the Bull : — " A Bull," he tells us,

" is the exact counterpart of a Witticism, for as Wit discovers real

relations that are not apparent, Bulls admit apparent relations that

Vol. XV. TNo. 90.) n

98 Mr. William Samuel Lilly [March 13

are not real." I do not think Bulls necessarily do that. When
Sir Boyle Eoche told the Irish House of Commons that he wished a
certain bill, then before that august assembly, at the bottom of the
bottomless pit, he certainly produced a Bull, and a very fine one ; but
as certainly his aspiration does not admit apparent relations that are
not real. It appears to me that a Bull may perhaps be defined — in
so difficult and subtle a matter I don't like to dogmatise — as a con-
tradiction in terms which conveys a real meaning. I observe in
passing — and I hope I may not in so doing seem to be lacking in
justice to Ireland — that the claim sometimes made on behalf of that
country to a sort of monopoly of Bulls is untenable. Excellent Bulls
are produced by people of other countries ; as, for example, by the
Austrian officer, mentioned by Schopenhauer, when he observed to
a guest staying in the same country house, " Ah, you are fond of
solitary walks, so am I ; let us take a walk together : " or by the
Scotchman who told a friend that a common acquaintance had
declared him unworthy to black the boots of a certain person, and
who in reply to his remark, " Well, I hope you took my part," said,
" Of course I did, I said you were quite worthy to black them : " or
again, by a well-known English judge, who when passing sentence
on a prisoner convicted on all the counts of a long indictment,
observed, " Do you know, sir, that it is in my power to sentence you
for these many breaches of the laws of your country, to a term of
penal servitude far exceeding your natural life."

There is yet another variety of the Ludicrous, upon which I
ehould like to say a few words — Parody. A Parody is a composition
which sportively imitates some other composition. I suppose that,
in the majority of cases, the object, or at all events, the effect of the
imitation is to cast a certain amount of ridicule upon the original.
*' What should be great you turn to farce " complains the honest
farmer to his wife, in Prior's amusing poem, ' The Ladle.' Well, it
must be confessed that this is what a Parody too often does. But
this need not be so. A Parody must necessarily be sportive, or it
would not belong to the great family of the Ludicrous; but the
laughter, or the smile, which it excites need not be at the expense
of the composition imitated. Pope speaks of his imitation of one of
the ' Satires ' of Horace as a Parody : but the laugh which he raises
does not fall upon Horace. So., you will remember, in the ' Dunciad '
he most effectively parodies certain noble lines of Denham's ' Cooper's
Hill ' — lines addressed by that poet to the river Thames : —

" 0 could I flow like thee, and make thy stream
My great example, as it is my theme !
Though deep yet clear, though gentle, yet not dull,
Strong without rage, without o'erflowing full."

Fine verses, indeed, are these : perhaps the finest example of that
strength with which Pope, in a well-known line, rightly credits

1896.] on the Theory of the Ludicrous, 99

Denham. And, assuredly, Pope by no means intended to ridicule
them, wlien he addressed the unhappy Welsted : —

" Flow, "Welsted, flow, like thine inspirer Beer ;
Though stale, not ripe ; though thin, yet never clear ;
So sweetly mawkisli, and so smoothly dull ;
Heady, not strong ; o'erflowing, though not full."

So much must suffice regarding the four varieties of the
Ludicrous, which seem to me to present special difficulties. What I
have said may serve to show how wide and varied its range is, and
how many things have to be thought of and taken into account before
we can even attempt to frame a theory of it. But, indeed, that is
not all. The matter is further complicated by national differences.
This is especially so in the case of Humour. Spanish Humour, for
example — its chief monument is, of course, Don Quixote — differs very
widely from all other. It is impossible to conceive of that marvel-
lous book as being written out of Spain, not merely on account of its
local colouring, but also, and far more, on account of its ethos, its
indoles. Pope, in dedicating to Swift the ' Dunciad,' writes : —

" Whether thou choose Cervantes' serious air.
Or laugh and shake in Rabelais' easy chair."

The lines are singularly infelicitous. The Castilian gravity of Cer-
vantes is one thing. The British gravity of Swift is quite another.
Nor is there much in common between Eabelais and Swift. Rabelaia
is the supreme example of what Eenan has called *' the old Gallic
gaiety " — it seems now well nigh extinct in France — in its moods of
wildest and most unrestrained extravagance. Swift, "bitter and
strange," is ever sober, ever holds himself in hand. Eabelais ! Yes :
we picture him to ourselves in his easy chair, laughing consumedly,
quaffing his cup of good old wine to warm his good old nose, and
ministered to, like Falstaff, " by a fair hot wench in a flame-coloured
taffeta." Swift's most outrageous utterances are delivered with all
the solemnity — I think this has been remarked by Taine — of a
clergyman discoursing in his gown and bands. I can only glance at
this subject of the difference in the Humour of different races. It is
too large, and would want a lecture, or rather a book, to itself, for
any adequate treatment. But, before I pass on, I should like to
observe how distinctly a thing sui generis American Humour is. It
is, I think, the only intellectual province in which the people of the
United States have achieved originality. I cannot here enter upon an
analytical and comparative examination of it. I suppose its peculiar
charm lies in its homely and fresh grotesqueness. The dryness and
crispness of the American climate seem to have passed into it«
Lowell is unquestionably one of its chief masters.

H 2

100 Mr. William Samuel Lilly [March 13,

" Parson Wilbur sez he never heerd in his life
That th' Apostles rigged out in their swaller-tail coats,
And marched round in front of a drum and a fife,
To git, some of 'em office and some of 'em votes ;

But John P.

Eobinson, he
Sez they didn't know everything down in Judee."

Artemus Ward, another great master of American humour, has
not surpassed this. But I think he has equalled it : as, for example,
in his account of his visit to Brigham Young : —

" You are a married man, Mr. Young. I bleeve," says I, preparing to write
him some free piirsis.

" I've 80 wives, Mr. "Ward. I sertinly am married."
*' How do you like'it as far as you hev got ? " said I.
He said, " Middlin."

But the American newspapers, even the humblest of them, con-
stantly contain things just as good. A correspondent the other day-
sent me some obscure journal, published in the far West, I think,
wherein I found a story which strikes me as so superlatively excellent a
specimen of American humour that I shall venture to read it to you.
It is called, " A Cool Burglar, Too."

" I think about the most curious man I ever met," said the retired burglar,
" I met in a house in Eastern Connecticut, and I shouldn't know him either if I
should meet him again, unless I should hear him speak ; it was so dark where
I met him that I never saw him at all. I had looked around the house down-
stairs, and actually hadn't seen a thing worth carrying off, and it wasn't a bad
looking house on the outside, either. I got upstairs, and groped about a little,
and finally turned into a room that was darker tban Egypt. I hadn't gone more
than three steps in tliis room when I heard a man say, ' Hello, there.'

" ' Hello,' says I.

" ' Who are you ? ' said the man, ' burglar ? '

" And I said yes, I did do something in that line occasionally.

" ' Miserable business to be in, ain't it ? ' said the man. His voice came from
a bed over in the corner of the room, and 1 knew he hadn't even sat up.

" And I said, ' Well, I dunno ; I've got to support my family someway.'

" ' Well, you've just wasted a night here,' said the man. ' Didn't you see
anything downstairs worth stealing ? '

" And I said no, I hadn't.

" ' Well, there's less upstairs,' says the man, and then I heard him turn over
and settle down to go to sleep again. I'd like to have gone over there and
kicked him. But I didn't. It was getting late, and I thought, all things con-
sidered, that I might just as weU let him have his sleep out."

And now having thus taken, so to speak, a bird's-eye view of the
vast domain of the Ludicrous, let us go on to inquire if we can arrive
at any true theory about it. Can we define the Ludicrous ? Is there
a Ludicrous in the nature of things — an Objective Ludicrous, as well
as a Subjective Ludicrous ? In other words, what is the Ludicrous
in itself, and what is it to us ? And what is the faculty which com-
prehends and judges the Ludicrous ? These are questions which con-
front us when we seek to deal with the matter philosophically. And

1896.] on the Tlieoi-y of the Ludicrous. 101

they are questions wliicli it is far easier to ask than to answer.
Plato, in the ' Philebus,' tells us " the pleasure of the Ludicrous
springs from the sight of another's misfortune, the misfortune, how-
ever, being a kind of self-ignorance that is powerless to inflict hurt."
A certain spice of malice, you see, he held to be of the essence
of this emotion. Well, that may be so. It is always perilous
to differ from Plato. But certainly his account is inadequate,
as, indeed, is now pretty generally allowed. Far profounder
is the view expounded by Aristotle, here, as in so many provinces,
" the master of them that know." " The Ludicrous," he tells us in
* The Poetics,' "is a defect of some sort (ajxapT-qixa tl) and an ugli-
ness (atcrxo?), which is not painful or destructive." These are
words which, at first, may not seem very enlightening. But, as
Professor Butcher admirably remarks, in his edition of ' The Poetics,'
we cannot properly understand them without taking iuto account the
elements which enter into Aristotle's idea of beauty. And when we
have done that, we shall find that we may extend their meaning so as
to embrace " the incongruities, absurdities, or cross purposes of life,
its imperfect correspondences or adjustments, and that in matters
intellectual as well as moral." Aristotle's view of the Ludicrous
appears to be, in fact, something out of time and j3lace without
danger, some error in truth and propriety, which is neither painful
nor iDcrnicious. The treatment of the Ludicrous by the schoolmen is
worth noting, as indeed is their treatment of every question to which
they have applied their acute and subtle intellects. Their philosophy
goes upon Plato's notion of ideals or patterns in the divine mind,
compared with which individuals, both in themselves and in their
relations with one another, fall short of perfection. This deficiency,
they teach, when not grave enough to excite disgust or indignation, is
the ground — the fundamentum reale — of our subjective perception of
the Ludicrous. I believe I have looked into most of the modern
philosophers who have dealt with this matter, and 1 do not think that,
with one exception — to be presently dwelt upon — they take us much
beyond the ancients and the schoolmen. Of course we have attained
to a clearer perception of its physical side. And here we are
indebted to Mr. Herbert Spencer for an explanation, which, so far as
I can judge — and that is not very far — may very likely be true.
This is the substance of it. " A large amount of nervous energy,
instead of being allowed to expend itself in producing an equivalent
amount of the new thoughts and emotions which were nascent, is
suddenly checked in its flow." " The excess must discharge itself in
some other direction, and there results an efflux through the motor
nerves to various classes of the muscles, producing the half-convulsive
actions we term laughter." I dare say Mr. Spencer may be right in
the hypothesis he here presents. But I am sure he is wrong if he
supposes that those " nervous discharges," of which he speaks, are the
primary or the main element in the emotion of which laughter is an
outward visible siffn. That emotion begins with a mental act. As

102 Mr. William Samuel Lilly [March 13,

Lotze well puts it in his ' Microcosmos,' " The mechanism of our life
has annexed the corporeal expression to a mood of mind produced by
what we see being taken up into a world of thought, and estimated
at the value belonging to it in the rational connection of things."
Of course, the corporeal expression is not necessarily connected with
the mood of mind. Tlie physical phenomenon which we call laughter
may be produced by purely physical means, for example, by titillation.
The laugh of the soul and the laugh of the body are distinct- We
may have each without the other. And only a gross and superficial
analysis will confound them.

But, as I intimated just now, there is oce modern philosopher
who appears to me to have given us a satisfactory formula of the
Ludicrous. That philosopher is Schopenhauer, unquestionably one
of the most profound and penetrating intellects of this century, how-
ever we may account of his system as a whole. One of his cardinal
doctrines is that all abstract knowledge springs from knowledge of
perception, and obtains its whole value from its relation to percep-
tion. And upon this doctrine he hangs his theory of the Ludicrous.
" The source of the Ludicrous," he teaches, " is always the paradoxical,
and therefore unexpected, subsumption of an object under a concep-
tion which in other respects is diflerent from it." Or, as he elsewhere
in his great work, writes more at large : —

" The cause of laughter, In every case, is simply the sudden perception of the
incongruity between a concept and the real objects which by means of it we
have thought in a certain association, and laughter itself is the expression of
this incongruity. Now incongruity occurs in tliis way: we have thought of
two or more real objects by means of one concept, and have passed on the
identity of the concept to the objects. It then becomes strikingly apparent,
from the discrepancy of the objects, in other respects, that the concept applies
to them only from one point of view. It occurs quite as often, however, that
the incoDgruity between a single real object and the concept under which from
one point of view, it has rightly been subsumed, is suddenly felt. Now the
more correct the subsumption of such objects under a concept may be from one
point of view, and the greater and more glaring their incongruity from another
point of view, the stronger is the ludicrous effect which is produced by this
contrast. All laughter, therefore, springs up on occasion of a paradoxical and
unexpected subsumption, whether this is expressed in words or actions."

Now, I believe this account to be, in the main, correct. It is, in
substance, the thought of Aristotle, but it brings in the element of
paradox, unexpectedness, suddenness, which is lacking in that
philosopher's definition. And it is cast into an accurate and
scientific form. "The source of the Ludicrous is always the
paradoxical, and therefore unexpected, subsumption of an object
under a conception which, in other respects, is different from it."
Yes ; I think that this is true. Every instance of the Ludicrous, in
its twenty-one varieties, which I have been able to call to mind, fits
in with this formula. But there are two points in Schopenhauer's
exposition to which I must demur. In the first place, I do not think
Jiim well warranted in affirming — as he does — that his theory of the

1896.] on the Theory of the Ludicrous. 103

Ludicrous is inseparable from his particular doctrine of perceptible
and abstract ideas. And therefore it is not necessary for me, on the
present occasion, to enter upon an examination of that doctrine ; of
which I am heartily glad, for to do so, even in briefest outline,
would take up far more time than is left of my hour. Besides, I
hate talking metaphysics after dinner, and I fancy very few people
really like hearing metaphysics talked at that period of the day.
Again, Schopenhauer certainly uses unguarded and too general
language when he tells us that all laughter is occasioned by the
paradoxical, and therefore unexpected, subsumption of an object
under a conception which in other respects is different from it. The
phenomenon of laughter may be due to a variety of causes. It may
be due to merely physical causes, as I pointed out just now. It may
be due to quite other mental causes than paradoxical and unexpected
subsumption. Paradoxical and unexpected subsumption is not the
explanation of the heavenly laughter of which Dante speaks in the
twenty-seventh canto of the ' Paradise ' — the laughter of Beatrice, " so
gladsome that in her countenance God himself appeared to rejoice."

" Ma ella che vedeva il mio disire
Incommincio, ridendo, tanto lieta
Che Dio parea nel suo volto gioire."

It is not the explanation of what is called fiendish laughter, laughter
propter malitiam, the outcome of mere malice — the sort of laughter
which, by the way, one of his critics has attributed to Schoj^enhauer
himself; the laugh of a demon over the fiasco of the universe. It is
not the explanation of that ringing laugh of pure human happiness
which one sometimes hears from the lips of young girls ; is there any
music like it ? They laugh as the birds sing. Nor is the laughter
of women at their lovers — a common phenomenon enough — always to
be referred to the paradoxical and therefore unexpected subsumption of
an object under a conception which in other respects is different from
it. It is far oftener the expression of mere triumph. " The out-
burst of laughter," Dr. Bain truly tells us in his ' Mental and Moral
Science,' " is a frequent accompaniment of the emotion of power,"
But it is sometimes a manifestation of pain too deep for tears. This
is the laughter of which Antigone speaks : 'AXyovaa [xkv Stjt d yeAwr'
€v o-oi yeAto — " I laugh in sorrow if I laugh at thee." That laugh of
sorrow — so piercing and pathetic ! — who does not know it ? Surely it
is the saddest thing in the world. Lastly, not to continue unduly
the enumeration, laughter is very often the expression of mere mental
vacuity. I remember a gentleman who was fond of relating utterly
imbecile stories concerning himself, the invariable ending of them
being, " And then I roared." We gave him the name of the Eoarer,
and fled at his approach as we would have done from a ramping and
roaring lion. But I am quite sure his laughter was not due to the
paradoxical, and therefore unexpected, subsumption of an object under
a conception which in other respects was difl'ercnt from it. No ; his

104 Mr. William Samuel Lilly [March 13,

was the inane laughter which Cicero justly calls the most inane
thing in the world : inani risu nihil est inanius.

With these reservations, then, I think we must admit Schopen-
hauer's theory of the Ludicrous. It is true as far as it goes. I use
those words of limitation, because it does not attempt to answer the
deeper questions connected with the subject which I mentioned just
now. Perhaps they are unanswerable. Certainly the few minutes
left to me will not suffice even for the most superficial examination of
them. I would rather employ those minutes for another and more
practical purpose : an Englishman is nothing if not practical. We
have seen what the Ludicrous is : the paradoxical, and therefore
unexpected, subsumption of an object under a conception which, in
other respects is different from it. Well, but what is the function of
the Ludicrous in human life ? What end does it serve ? Please note
that this question is quite congruous with the title of my lecture : for
in order really to know anything, we must know its end : according
to that profound saying of Aristotle, rj Sk cfivcnq reXos ecrrt.

I observe, then, that a sense of the Ludicrous is the most sane
thing we have. Incorrectness and abnormality are the notes of the
Ludicrous. And, they provoke one to affirm — ridentem dicer e verum
— what is correct and normal. We may say then, that the Ludicrous
is an irrational negation which arouses in the mind a rational affirma-
tion. And so, in strictness, a sense of the Ludicrous cannot be
attributed to animals less highly evolved than man in the scale of
being: because, though they have understanding, they have not,
properly speaking, reason; they have knowledge of perception ; they
have not abstract knowledge. Still, in this province, as elsewhere, we
may observe among them what Aristotle calls /xt/xTy/xara r^s avOfi(j)7rivrj<s
t,o)rjs : mimicries of the life of man. As in the most favoured in-
dividuals of the higher species of them there appear analoga of the
operations of reason, so do we find also indications of the lower kinds
of the Ludicrous : farce, buffoonery, practical joking. But, indeed,
there appear to be whole races of men — the North American Indians
and the Cingalese Yeddas, for example — that are destitute of the sense
of the Ludicrous. And, in the higher races this sense is by no means
universally found. The richest intellects possess it in amplest
measure. The absence of it is a sure indication of mental poverty.
*' Here comes a fool, let's be grave," said Charles Lamb on one occa-
sion. And, I remember a friend of my own observing of a somewhat
taciturn person whom we had met, " He must be a man of sense, for,
although he said little, he laughed in the right place." That laugh
is a manifestation of intellectual abundance or exuberance : it is
something over and above the actual work of life. And so we may
adapt to our present purpose certain words of Schiller's in his ' Letters
on Esthetic Education ' : " Man sports (spielt) only when he is man in
the full signification of the word : and then only is he complete man
(^ganz Mensch) when he sports."

I need hardly observe how grossly this faculty of the Ludicrous

1896.] on the Theory of the Ludicrous. 105

may be abused. There is notbing more diabolical — in the strictest
sense of the word — than to turn into ridicule " whatsoever things are
true, w^hatsoever things are honest, whatsoever things are just, what-
soever things are pure, whatsoever things are lovely, whatsoever
things are of good report." There is no more detestable occupation
than that of " sapping a solemn creed with solemn sneer." But it
is a maxim of jurisprudence, Ahusus non tollit usum. And this
holds universally. No; the abuse of the Ludicrous does not take
away its uses. Those proper, healthy and legitimate uses are
obvious. And very few words will suffice for such of them as I can
here touch on. Now one office of the Ludicrous is to lighten " the
burden and the mystery of all this unintelligible world." Beaumar-
chais has indicated it in his well-known saying : " I make haste to
laugh at everything for fear of being obliged to weep." I remember
a story of the late Lord Houghton meeting some obscure author who
had given to the world a play, and exclaiming, with his usual bon-
homie, " Ah ! Mr. So-and-So, I am so glad to make your acquaintance :
I remember reading your tragedy with great interest." " Tragedy ! "
the other explained in dismay : " no, no ; it was a comedy." " God
bless my soul," Houghton replied, " I thought it was a tragedy ;
please forgive me." Well, " life's poor play " is tragedy or comedy,
as you take it. It is best not to take it a? tragedy, at all events too
habitually. A certain novelist, I forget who, says of a certain lady
who adorns his pages, I forget her name, that on a certain occasion,
I forget what, " not knowing whether to laugh or cry, she chose the
better part, and laughed." It is the better part. And one office of
Humour — to speak only of that variety of the Ludicrous — is to show
us the folly of quarrelling with such life as we have here. Ah, it is
so easy to strip oif the illusions of human existence ! And so foolish !
Yes ; and may we not add, so ungrateful ? For, assuredly, the
Almighty Hand which has hung the veil of Maya over the darker
realities of life, was impelled by pity for the "purblind race of
miserable men." Illusions ! what would the world be without them ?
And it is the function of the humourist to teach us to enjoy them
wisely ; to lead us to make the most of life's poor play, while it lasts ;
which assuredly we shall not do if we are for ever examining too
curiously the tinsel and tawdry which deck it out, if we are for ever
thinking of the final droj) of the curtain upon " the painted simulation
of the scene," and the extinguishment of the lights for ever. Memento
mori is undoubtedly a most wholesome maxim. So is Disce vivere.
" Ah, mon enfant," said the old priest, touching lightly with his
withered hand the blooming cheek of the young girl, too vain of her
pretty face, " Ah, mon enfant, tout cela pourrira." " Oui, mon pere,"
she replied, naively, " mais ce n'est pas encore pourri." Well, they
were both right, the sage confessor and the silly coquette. And we
may learn a lesson from them both. There is an admirable saying of
Joubert, " L'illusion et la sagessc reunics sout le charmc dc la vie et
de I'art."

106 On the Theory of the Ludicrous. [March 13,

But again, the Ludicrous has a distinct ethical value. Aristotle
places evrpaTreXla among the virtues, and by evrpaTreXla he means
decorous wit and humour, as distinguished from the low buffoonery
to which Dr. Kennedy so strongly objected. It is said that ridicule
is the test of truth. And there is a true sense in the saying. The
Platonic irony — which is really the feigning of ignorance in order to
get a man to make a fool of himself — may illustrate this. And, to
look at the matter from another point of view, it may be seriously
maintained that we never really believe a thing until we are able to
treat it sportively. The more profound our wisdom, the more lightly
we shall wear it. It is a tradition of the Catholic Church, in her
colleges and seminaries, that all ethical questions should be dealt with
humorously. The Professor of Moral Philosophy in those institu-
tions is " der Lustige," as the Germans would say : the man who
does the comic business. Carlyle, in one of his early Letters, speaks
of a sense of the ridiculous as " brotherly sympathy with the down-
ward side." It is a most pregnant saying. " Twenty-seven millions,
mostly fools." Well, better to view them as fools than as knaves.
For the emotion raised by folly is rather pity and ruth than anger.
Then again, the Ludicrous, and especially the variety of it which we
call Satire, is an inestimable instrument of moral police. I do not say
of moral reformation. "What moral reformation really means is the
conversion of the will from bad to good. And I do not think Satire,
as a rule, likely to effect that. But it is certainly a most effective
deterrent. Goethe makes Werther, as the supposed author of the
* Letters from Switzerland,' say, " One would always rather appear
vicious than ridiculous to any one else." And I suppose this is true
of the vast majority of people. Hence it was that Pope was led to
magnify his of&ce : —

" Yes, I am proud, I must be proud, to see
Men not afraid of God, afraid of me ;
Safe from the Bar, the Pulpit and the Throne,
But touched and scared by ridicule alone."

But the clock, which beats out the little lives of men, has beaten out
the brief hour of the lecturer. And so with these noble lines of the
great ethical poet of the last century, I take my leave of my subject
and my audience.

[W. S. L.]

1896.] Immunisation against Serpents^ Venom. 107

WEEKLY EVENING MEETING,

Friday, March 20, 1896.

Sir James Ceichton-Browne, M.D. LL.D. F.E.S. Treasurer
and Vice-President, in tlie Chair.

Professor Thomas E. Eraser, M.D. LL.D. F.R.S.

Immunisation against Serpents' Venom, and the Treatment of
Snahe-bite with Antivenene.

From a remote period of antiquity, there has been enmity between
the human race and serpents, and, in a literal sense, man has bruised
the head of the serpent, and the serpent has bruised the heel of man.
This long-continued feud has not resulted in victory for either side.
Venomous serpents still annually destroy the lives of tens of thou-
sands of human beings, and, in self-defence, tens of thousands of
serpents are annually slain by man.

The progress of knowledge has greatly increased the means for
protecting mankind against the death-producing effects of many
diseases ; yet, although these means have been liberally employed in
the contest against venomous serpents, none of them have hitherto
been found sufficient.

The reality of the contest is appreciated when we find pervading
medical literature from its earliest beginnings — from the time of
Pliny and Celsus — to the present time, disquisitions on the treatment
of the bites of venomous serpents, and lengthy descriptions of the
numerous remedies, organic and inorganic, that have been used for
this purpose. Although extended experience and the application of
the scientific methods of the present day, have resulted in showing
that each of these remedies had been recommended on insufficient
grounds, we may hesitate in pronouncing their recommendation to
have been premature, in view of the impossibility of waiting, in the
presence of imminent dangers, until accurate demonstration has been
obtained by the usually tardy and laborious processes of science.

Let me pause here for a few minutes to indicate the practical
importance of a scientific demonstration of the value of any remedy
that is used in the treatment of snake-poisoning.

When a serpent inflicts a wound, I need scarcely say that it is
not the wound, but the venom introduced into it which causes the
symptoms of poisoning, and the death that may result. This venom
is now known to be a complex mixture, containing several non-
poisonous as well as poisonous substances. The latter arc not

108 Professor Thomas B. Fraser [March 20,

ferments, and have no power of reproducing themselves in the body,
but they are substances that produce effects having a direct relation-
ship to the quantity introduced into the body. This quantity in the
case of each serpent varies with its size and bodily and mental
condition ; with the nature of the bite — whether both fangs or only
one has been introduced, whether they have penetrated deeply or
only scratched the surface ; and with other circumstances related to
the serpent, such as whether it had recently bitten an animal or not,
and thus parted with a portion or retained the whole of the venom
stored in the poison glands.

A bite may, therefore, result in very little danger, or it may be
rapidly fatal ; but, in order to produce death, there must have been
introduced into the tissues at least a certain quantity of venom, which
is spoken of as the minimum-lethal quantity or dose. The minimum-
letbal quantity for the animal bitten, again, is different for different
species of animals, and different also for different individuals of the
same species, the chief cause of difference between adult animals of
the same species being the body weight of the individual, the quantity
required to produce death being very exactly related to each pound
or kilogramme of weight.

If even a minute fraction below the minimum-lethal has been
introduced into the tissues by an effective bite, death will not follow,
although serious and alarming symptoms will be produced of exactly
the same kind as those which follow a bite which terminates fatally.

How then can we be assured, in any case of snake-bite in man,
that a quantity of venom sufficient to produce death has been intro-
duced ? It is impossible to answer this question except by the result.
If a quantity less than the minimum-lethal has been introduced,
although the gravest symptoms may be produced, the patient will
recover, whatever remedies are administered, provided, obviously, that
the remedies have not been so injudiciously selected or used that they
themselves, and not the insufficient quantity of venom, produce a
fatal termination. The recovery of a patient after the introduction
of less than the smallest quantity of venom capable of producing
death, has thus too often been attributed to the remedies that have
been administered ; and, consequently, as, indeed, is exemplified in
the treatment of many diseases, a large number of substances have
acquired an unjust reputation as antidotes. The list of antidotes has,
accordingly, become a very large one; but when their pretensions
have been subjected to sufficient tests, the verdict is that all of
them are valueless to prevent death when even the smallest quantity
of venom required to produce death has been received by an animal.

Without entering into details, I will content myself with re-
producing the opinion of Sir Joseph Fayrer, that, " after long and
repeated observations in India, and subsequently in England, I am
forced to the conclusion that all the remedies hitherto regarded as
antidotes are absolutely without any specific effect on the condition
produced by the poison."

But while medical practice and science, in each period of its

1896.] on Immunisation against Serpents' Venom. 109

development, has thus failed to protect man against this ancient
enemy, legendary traditions, the tales of travellers and of residents
among nations and tribes existing outside of the civilisation of the
time, at least suggest that, by means apart from the use of remedies,
some measure of success may actually have been obtained.

Many of these legends and statements are probably of great
significance, and, in connection with facts derived from experiment,
which to-night I have to describe, they possess a deep interest.

We learn from these legends that from a remote period of time
the belief has existed that a power may be acquired by man of
freely handling venomous serpents, and even of successfully resisting
the poisonous effects of their bites.

The Psylli of Africa, the Marsi of Italy, the Gouni of India, and
other ancient tribes and sects, were stated to have been immune
against serpents' bites, and this immunity has been explained on the
supposition that serpents' blood was present in the veins of the
members of these tribes and sects.

In more modern times and, indeed, at the present day, the same
belief is expressed in the writings of many travellers. In ' A New
and Accurate Description of the Coast of Guinea,' by William Bosman,
published in 1705, an account is given of the great " reverence
and respect " of the negroes for snakes, worshipped by them as gods ;
in connection with which the following statements are made. " But
what is best of all is that these idolatrous snakes don't do the least
mischief in the world to mankind ; for if by chance in the dark one
treads upon them, and they bite or sting him, it is not more pre-
judicial than the sting of millipedes. Wherefore the natives would
fain persuade us that it is good to be bitten or stung by these
snakes, upon the plea that one is thereby secured and protected from
the sting of any poisonous snake " (p. 379).

At Southern Africa, the Eev. John Campbell, in 1813, observed
that it was '' very common among the Hottentots to catch a serpent,
squeeze out the poison from under his teeth, and drink it. They
say it only makes them a little giddy, and imagine that it preserves
them afterwards from receiving any injury from the sting of that
reptile" (p. 401).

Drummond Hay, in his work on Western Barbary, published in
1844, gives a description of the performances by members of a sect
of snake-charmers, called the Eisowy, who freely handled, and
allowed themselves to be bitten by serpents proved to be venomous
by a rapidly fatal experiment performed on a fowl. At the ter-
mination of the exhibition, the Eisowy, apparently as a usual part
of the performance, " commenced eating or rather chewing " a poison-
ous snake, " which, writhing with pain (to quote Mr. Hay's words),
bit him in the neck and hands until it was actually destroyed by
the Eisowy's teeth." He states that, on another occasion, at Tangier,
a young Moor, who was witnessing the performance of a snake-
charmer, ridiculed his exhibition as an imposture, and having been
dared by the Eisowy to touch one of the serpents, the lad did so,

110 Professor Thomas B. Fraser [Marcli 20,

was bitten by one of them, and shortly afterwards expired. In
connection with my subject, a special interest is attached to the
account given by Mr. Drummond Hay, and repeated in its main
features by Quedenfeldt in the ' Zeitschrift fiir Ethnologic ' of 1886,
of the origin of this Eisowy sect, and of the immunity which they
claim. The founder, Seedna Eiser, was being followed through the
desert of Soos by a great multitude, who, becoming hungry, cla-
moured for bread. On this, Seedna Eiser became enraged, and
turning upon them he uttered a common Arabic curse, " Kool sim,"
which means " eat poison." So great was their faith in the teaching
of the saint, that they acted upon the literal interpretation of his
words, and thereafter ate venomous snakes and reptiles ; and from
that time they themselves and their descendants have been immune
against serpents' bites (p. 65).

Dr. Honigberger, in his ' Thirty-five Tears in the East,' pub-
lished in 1852, relates the incident of a faqueer who was bitten by a
serpent, and to whom he at once sent medicines which he judged
likely to prevent the ill-effects of the venom. " On the same after-
noon," he writes, " I visited him and found him in good spirits. I
at first attributed the circumstance to the effect produced by the
remedies I had sent him, but was surprised on hearing that he had
not taken them, he being of opinion that the venom of the serpent
was incapable of affecting him, inasmuch as he had often been bitten
by serpents without having sustained any injury." On the sugges-
tion of the faqueer, the same serpent, which had been caught and
retained, was allowed to bite him again, and afterwards to bite a
fowl. This fowl was taken home by Dr. Honigberger, and he found
it dead on the following morning, " although the faqueer, who was
bitten first, was quite well " (p. 135).

Nicholson, in his work on 'Indian Snakes' (1875), and Kichards,
in his 'Landmarks of Snake-poison Literature ' (1885), also narrate
instances, the latter with obvious disbelief in their reality, suggest-
ing that snake-charmers may possess some means for protecting
themselves against the bites of venomous serpents.

Many other examples might be quoted in which this suggestion
is made. The attention which has been drawn to the subject during
the last twelve months has prompted the publication of other
instances, such as that related by Dr. Bawa, of a Tamil snake-
charmer who, in the course of his performances, was bitten by a
cobra without any effect, while an onlooker, foolishly repeating the
performance, was bitten by the same cobra, and died in three hours ;
and the description given by M. D'Abbadie, in a recent issue of the
Comptes rendus, of the custom, recently prevailing at Mozambique, of
inoculating with serpents' venom, under the firm conviction that pro-
tection is thereby produced against the effects of serpents' bites.

It may be instructive to associate with these statements the
belief that venomous serpents are themselves protected against the
effects of bites inflicted upon them by individuals both of their own
and of other species. On mere anatomical grounds, it is difiicult to

1896.] on Immunisation against Serpents' Venom. Ill

understand how serpents could escape the absorption of their own
venom through mucous surfaces, even admitting that absorption of
venom does not occur in normal conditions of these surfaces. Venom
must, however, be so frequently introduced into their bodies, in situa-
tions where absorption could not fail to occur, by the bites inflicted
upon them by other serpents, that the conclusion seems inevitable
that they possess some protective quality, without which, probably,
no venomous serpents would now be in existence. Not only have
many general observations been made in favour of this belief, but it
has been supported by direct experiments, such as those made by
Fontana of Tuscany more than a century ago, and by Guy on,
Lacerda, Waddell, Kaufmann, and Sir Joseph Fayrer.

This, and other evidence, pointing to the existence of protection
against venom, not only in serpents themselves, but also, in certain
exceptional circumstances, in human beings, several years ac^o ori-
ginated a wish to investigate the matter. It was obviously suggested
that if protection occurs, it must be caused by some direct result of
the absorption of venom ; and, therefore, that its existence could be
proved or disproved by experiment. In the former event, the first
steps would already have been taken to obtain, by further experi-
ments, results likely to be of value in the treatment of poisonino- by
serpents' venom, and, indeed, likely to be of suggestive importance in
even the wider field of general therapeutics.

The general plan to be followed in the first stages of the investi-
gation was obviously suggested by some of the statements I have
reproduced ; for they indicate that individuals might become accus-
tomed to, or protected against the effects of serpents' bites, by the
introduction into their bodies of a succession of doses of venom,
no one of which, necessarily, at the beginning of the process, was so
large as the minimum-lethal. A consideration also of the facts,
proving the possession of protection on the part of venomous serpents
themselves, indicated the same plan of procedure ; for, equally
obviously, these serpents, from an early period of their existence,
must absorb venom from their own gradually-developing poison-
glands, until, in the course of time, they had acquired sufiicient
protection to remain unaffected by the larger quantities which the
now fully-developed glands would introduce into their bodies.

My first supplies of cobra venom were obtained in 1869, from
the late Dr. Shortt, of Madras, and in 1879 from Surgeon-Colonel
Moir, of Meerut. They were in very small quantity, but with them
1 was able to satisfy myself that, by a succession of minute doses,
animals became able to receive the minimum-lethal dose without any
distinct injury. At this point, however, the supply of venom failed,
and the observations could not then be carried further. It became
evident that until large quantities of venom had been obtained,
definite results could not be hoped for.

It was not until several years afterwards that a sufficient supply
had been gradually accumulated, by further small quantities received
from Sir Joseph Fayrer, the Thakore of Gondal, and Dr. Phillips ;

112 Professor Thomas B, Fraser [March 20,

and by larger quantities from Sir William Mackinnon, Director-
General of the Army Medical Department, and especially from
Surgeon-Colonel Cunningham, of Calcutta, who for many years has
been engaged with much success in the study of venoms and their
antidotes. Within the last few months, and subsequently to the
publication of some of the experimental results which had by this
time been obtained, the India Office has also placed at my disposal
a considerable quantity of venom, which had been collected by
Dr. Hankin, of Agra, at the request of Dr. Cleghoorn, Surgeon-
General with the Government of India.

But, besides these specimens of the venom of the cobra of India,
I have also been fortunate in obtaining specimens of venoms from
other parts of the world.

From America, Dr. Weir Mitchell, of Philadelphia — whose work
on the chemistry and physiology of serpents' venom constitutes the
great advance of the century on the venom of viperine serpents — has
supplied me with the venom of three species of rattlesnakes, viz.
Crotalus horridiis, C. aclamanteus, and C. durrisus, and also with a
specimen of the venom of the Copper Head [Trigonoceplialus contor-
trix).

From Australia, Dr. Thomas Bancroft, of Brisbane, has at various
times sent specimens of the venoms of the black snake (PseiidecMs
porphyriacus\ the brown snake (Diemenia sujperciliosa), and of a
large unidentified snake of the Diamantina district of Queensland
(probably a new species of Diemenia).

From Africa, the kindness of Mr. Andrew Smith, a distinguished
naturalist of Cape Town, of Dr. Brook, of the Orange Free State,
and of Dr. John Murray and Mr. Van Putten, of Cape Colony, has
placed at my disposal small quantities of the venom of the puff adder
(Vifera arietans), the night adder (Aspidelaps luhricus), the yellow
cobra {Naja liaie\ and the " Ring Hals Slang " or " Einkas "
(Sepedon Jisemacliates).

In the meantime, however, the results of experiments on the
inoculation of the toxines of diseases, as well as of proteid toxines of
vegetable origin, had suggested to several observers that serpents'
venom, because of its chemical analogies with several of these sub-
stances, might possibly be found capable, like them, of producing
immunity against the effects of poisonous doses ; and further impor-
tant evidence has thus been obtained in favour of the reality of the
protection to which I have referred.

Sew^all, in 1886, undertook an investigation with the object of
determining if immunity against the fatal effects of rattlesnake venom
could be produced by the inoculation of repeated doses, each too small
to produce ill-efiects. The experiments were made on pigeons, and
he succeeded in proving that immunity could be secured to the extent,
at least, of protection against seven times the minimum-lethal dose.
Kanthack made a similar series of experiments in 1891, which allowed
him to conclude that rabbits may be accustomed to resist lethal doses

1896.] on Immunisation against Serpents' Venom. 113

of cobra venom. Working with tlie venom of vipers, Kaufmann in
1891, and Phisalix and Bertrand in 1893, obtained experimental
evidence of tbe possibility of producing a definite, though not high
degree of resistance against the toxic effects of this venom. In the
following year, Calmette, continuing some earlier observations which
had led him to express the opinion that protection against snake
venom could not be produced, published evidence confirming the
results of previous investigators, but also showing that a higher
degree of protection could be secured than they had obtained, for he
succeeded in administering to each of several rabbits, within a period
of eight months, a total quantity of from 30 to 35 milligrammes of
venom.

In 1894, also, both Phisalix and Bertrand and Calmette obtained
evidence of the power of the blood-serum of protected animals to
counteract the effects of venom. Calmette at the same time claimed
that hypochlorite and chloride of calcium were antidotes of consider-
able value ; and in a later publication, he showed that the blood-serum
of animals immunised by the administration of venom possesses a
certain degree of antidotal efficacy against the toxines of several

In the case of many of the venoms which I have had the good
fortune to obtain, the quantity at my disposal was not sufficient for
experimental examination on the plan that seemed desirable, and,
besides, the examination of each of them would require several months
of work. The venoms that have as yet been used are four in number,
those namely of the cobra of India (Naja tripudians), of the Crotalus
Tiorridus of America, of a large colubrine snake, probably a species of
Diemenia from Queensland, Australia, and of the Sepedcm Jisemachates
of Africa. They are, therefore, those of the most deadly of the
poisonous serpents of Asia, America, Australia and Africa respec-
tively ; and, further, they are representative of the chief differences
that occur in the composition and action of venoms, for they are
derived from members of the two great groups of the colubrine and
viperine serpents. My supply of cobra venom, however, being much
larger than that of any of the others, this venom was chiefly used in
the experiments.

An esssential preliminary to exact investigations with active
substances must always be the determination of the activity of the
substances. The only convenient method for doing this is to define
the smallest dose capable of producing death for any given weight of
animal — that is, the minimum-lethal dose. The venoms in their natural
liquid state are unstable, and they are also inconstant in activity,
mainly because of variations in the quantity of the water which they
contain. Dried venoms have therefore been used in all the experi-
ments. The cobra venom has, however, nearly always been received
in the form of a dry solid ; but when this was not so, it has been
dried in vacuo over sulphuric acid.

Experiments were made with it on several animals — as the frog.

Vol. XV. (No. 90.) I

114 Professor Thomas B. Fraser [March 20,

guinea-pig, rabbit, white rat, cat, and the innocuous grass snake of
Italy {Tro'pedonotus natrix). Very considerable diiferences were
found to occur in the minimum-lethal dose for each of these animals.
For the guinea-pig, the minimum-lethal dose per kilogramme was
• 00018 grm. ; for the frog, • 0002 grm. ; for the rabbit, • 000245 grm. ;
for the white rat, '00025 grm.; for the cat, somewhat less than '005
grm. ; and for the grass snake, the relatively large dose of * 03 grm.*
Cobra venom thus takes a position among the most active of known
substances, rivalling in its lethal power the most potent of the
vegetable active principles, such as aconitine, strophanthin or
acokantherin.

These facts having been ascertained, attempts were next made to
render animals proof against lethal doses, by administering to them
a succession of gradually increasing non-lethal doses. These were,
for the first few doses, in some of the experiments, one-tenth of the
minimum-lethal, in others one-fifth, in others one-half of the mini-
mum-lethal, and in others almost as great as the minimum-lethal.
At varying intervals the doses were repeated, and by-and-by gradually
increased, until the actual minimum-lethal had been attained. The
subsequent doses by gradual increments exceeded the minimum-lethal,
and after five or six times the minimum-lethal had been reached, it
was found that the increments could be increased so that each became
twice, four times, and latterly even five times the minimum-lethal,
and still the animal suffered little, and, in many cases, no appreciable
injury. ^

This brief statement, however, does not represent the experi-
mental difficulties that were encountered. It describes the course of
events in the altogether successful experiments. Non-success, how-
ever, was frequent, and many failures occurred before experience
indicated the precautions and conditions that are necessary for
success.

Serpents' venom exerts what may broadly be described as a duplex
action. It produces functional disturbances unassociated with visible
structural changes, and it also produces obvious structural changes.
The latter are of a highly irritative character, causing intense vis-
ceral congestions in the lungs, kidneys, and other organs, and when
the venom is given by subcutaneous injection, on all the structures of
the skin and subjacent parts. There are apparently also some definite
changes produced in the blood, with regard to which several impor-
tant facts have been discovered by Dr. Martin, of the University of
Sydney, and by Surgeon-Colonel Cunningham, of Calcutta. Irrita-
tive effects arc obviously produced by cobra venom, even in non-lethal
doses, and with greatly increased virulence by doses that exceed the

* Guinea-pig, nearly a milli§

Kabbit, nearly \ „

White rat, \ „

Kitten (6 weeks), 2 miliig.
Cat, 5 „

Grass snake, 3 centig.

1896.] on Immunisation against Serpents' Venom. 115

minimum-lethal ; but, in respect to this action, the other three venoms
used are greatly more active than the venom of the cobra. Evidence
was obtained to indicate that in the process of immunisation a
diminution occurs in the intensity of these local actions; but this
diminution does not proceed so rapidly as that in the unseen func-
tional or other changes which are the more direct causes of death ;
and, further, the local irritative changes, after having been produced,
are slower to disappear than the unseen functional disturbances.
Until these facts had been appreciated, and, indeed, even with the
adoption of precautions suggested by them, frequent failures occurred.
The apparently contradictory results, accordingly, were obtained of
the production, by gradually increasing doses, on the one hand, of a
protection against quantities much above the minimum-lethal, so
perfect that no apparent injury was caused ; and, on the other hand,
when the intervals of time separating successive doses had been too
brief, of an intolerance so decided that death was i)roduced by the
last of a succession of gradually increasing doses, no one of which
was so great as the minimum-lethal. The latter unfortunate eveut
was frequently displayed in frogs and guinea-pigs, and attempts to
carry immunisation in them to a high point usually resulted in
failure.

Notwithstanding these difficulties, however, such gratifying results
have been obtained as that rabbits could at last receive, by sub-
cutaneous injection, so much as ten, twenty, thirty, and even the
remarkable quantity of fifty times the minimum-lethal dose, without
manifesting any obvious symptoms of poisoning.

Almost the only observable phenomena were a rise in the body
temperature, which continued for a few hours after the injection, and
which contrasts with the fall that occurs after the administration of
even non-lethal doses, in non-protected animals ; and a loss of appe-
tite, which usually, though not invariably, occurred, and was probably
the cause of a temporary fall in weight during the day or two days
succeeding each injection. On the other hand, during the process of
successful immunisation, the animals increased in weight, fed well,
and appeared to acquire increased vigour and liveliness.

It is marvellous to observe these evidences of the absence of
injurious effects, and even of the production of benefit in an animal
which, for instance, has received in one single dose a quantity of
venom sufficient to kill, in less than six hours, fifty animals of the
same weight, and in the course of five or six months a total quantity
of venom sufficient to destroy the lives of 370 animals of the same
species and weight (Fig. 1, overleaf).

With the cobra venom I have also immunised cats and white rats,
both by subcutaneous and by stomach administration ; but the sig-
nificance of the latter method of administration will be afterwards
considered. A horse has also been immunised ; and I have to express
my obligations to Principal Williams and Prof. W. Owen Williams
for granting me the accommodation of their establishment, and to

I 2

116

Professor Thomas R, Fraser

[March 20,

Mr. Davis, also of the New Veterinary College, for much valuable

Following the same plan of research with the three other venoms,
it was found "that for rabbits the minimum-lethal dose per kilogramme
of the Diamantina venom is 0*015 grm.; of the venom of Sepedon
Jisemachates, -0025 grm.; and of the venom of Crotalus, -004 grm.*
The Crotalus venom was, in its purity, altogether comparable with the
cobra venom; and the determinations, therefore, show that cobra
venom is sixteen times more powerful than Crotalus or rattlesnake
venom. This venom, as well as the two others, however, much
exceed cobra venom in the intensity of their local action. When
death is produced by Crotalus venom, the subcutaneous tissues become

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77 Days

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Fig. 1. — Immunisation of a rabbit against 50 times the minimum-lethal dose of
cobra venom. The crosses connected by the continuous line represent
administrations of venom. The dots connected by the interrupted line
represent the weights of the animal.

extensively infiltrated with a large quantity of blood and of blood-
stained serum, the underlying muscles are reduced to an almost
pulpy blood-stained substance, and decomposition occurs very soon
after death. Similar changes in the subcutaneous tissues, but to a
rather less degree, are caused by the Diamantina venom, and in addi-
tion, haematuria, or more probably hsemoglobinuria, was invariably
produced by lethal and by large non-lethal doses. I mention these
circumstances to indicate the perfection of the protection which is
produced by the administration of successive gradually increasing
doses; for they can be so adjusted that a dose of the Diamantina

* Diamantina venom, Ig milligramme.
Sepedon ha&macliates, 2J „

Crotalus Jwrridus, 4 „

1896.] on Immunisation against Serpents' Venom. 117

venom, even fifteen times larger tlian the minimum-letlial, may be
administered without producing more than an inconsiderable degree
of local destructive effect.

Experiments have also been made by which it has been demon-
strated that when an animal has acquired a resistant power over the
minimum-lethal dose of one venom, that animal is also able success-
fully to resist the lethal action of a dose above the minimum-lethal
of other venoms. To a rabbit protected against cobra venom, a dose
above the minimum-lethal of Sepedon venom has been administered ;
to rabbits protected against Crotalus venom, doses above the mini-
mum-lethal of Diamantina and of cobra venoms have been given ; to
rabbits protected against the Diamantina venom, doses above the
minimum-lethal of Crotalus and Sepedon venoms have been given ;
and in each case the animal has recovered, and but few symptoms of
injury were produced. At the same time, in other experiments,
indications were obtained that animals protected against a given
venom are capable of resisting the toxic effect of that venom more
effectually than the toxic effect of other venoms.

The experiments have not yet proceeded sufficiently far to show
for what length of time the protection conferred by any final lethal
dose may last. It has been discovered, however, that protection lasts
for at least a considerable period of time, even when the last protec-
tive dose has not been a large one. For example, to a rabbit which
had last received four times the minimum-lethal dose of cobra venom,
twice the minimum-lethal dose was administered thirty-four days
subsequently ; while to another rabbit, which had last received twice
the minimum-lethal dose of Crotalus venom, the same dose of this
venom was administered twenty days subsequently, and in each case
the second dose failed to produce any toxic symptom.

Having thus succeeded in producing a high degree of protection
in animals against the toxic effects of serpents' venom, the blood-serum
of these animals was, in the next place, collected for the purpose of
testing its antidotal properties. In this portion of the investigation,
the method followed was essentially the same as that described in a
communication made by me to the Eoyal Society of Edinburgh in
1871, on " The Antagonism between the Actions of Physostigma and
Atropia," as it appeared to be the most direct method for obtaining
accurate knowledge of the value of an antidote.

A few preliminary experiments were, however, early made with
the serum of animals in whom the protection had not been carried to
a high degree, and they were sufficient to show that antidotal proper-
ties are possessed even by this serum. It soon became apparent that
in order to obtain some reasonable approximation to constancy in the
conditions of the experiments, it was necessary that the serum should
be in such a state that it would remain unchanged during at least
several weeks. It was found that this could be insured, without any
appreciable loss of antidotal power, by drying the freshly-separated
serum in the receiver of an air-pump over sulphuric acid.

118 Professor Thomas B. Fraser [March 20,

A perfectly dry and easily pulverisable solid is thus obtained
from which a normal serum can readily be prepared as required, by
dissolving a definite quantity of the dry serum in a definite quantity
of water. The dry substance is on the average equivalent to about
one-tenth of the weight of the liquid serum. I have found that,
without any special precautions, it retains its antidotal power unim-
paired for at least a year, and it is probable that it may be kept
unchanged for an unlimited period of time.

To this antidotal serum, whether in the dry form or in solution,
I have given the name " Antivenene," a name which, notwithstanding
etymological objections, has the advantages of brevity and freedom
from ambiguity.

The experiments now to be described were made with antivenene
derived from a horse which had last received a dose of cobra venom
estimated to be twenty times the minimum-lethal. On some previous
occasions I have stated the results of observations on the antidotal
value of the blood-serum of rabbits which had last received thirty
and fifty times the minimum-lethal, respectively. The antivenene
obtained from cats and white rats has also been examined. The
special interest, however, is attached to antivenene derived from the
horse, that it is more likely than any others to be used in the treat-
ment of snake-bite in man.

The experiments were so planned as to obtain in difiierent con-
ditions of administration as exact a definition as possible of the
antidotal power of the antivenene. In the meantime, four series of
experiments have been undertaken on rabbits. In one series the
venom was mixed outside of the body with the antivenene, and
immediately^ thereafter the mixture was injected under the skin of
the animal ; in the second series the venom and antivenene were
almost simultaneously injected into opposite sides of the body ; in
the third series the antivenene was injected some considerable time
before the venom ; and in the fourth series the venom was first
injected, and thirty minutes afterwards the antivenene.

In the experiments of the first series, the doses of cobra venom
administered were the minimum- lethal, one-and-a-half the minimum
lethal, twice, thrice, four times, five times, eight times and ten times
the minimum-lethal. In the case of each dose of venom, experiments
were made with difterent quantities of antivenene, until the smallest
quantity required to prevent death was discovered. In order to
render it certain, in this and in the other series, that a lethal dose
had been administered in the experiments with the so-called minimum-
lethal, the minimum-lethal indicated by previous experiments was
not used, but instead of it a slightly larger dose ( • 00025 instead of
• 00024 gramme per kilogramme).

When this certainly lethal dose, capable of producing death in
three or four hours, was mixed with the antivenene, and the mixture
injected two minutes afterwards, under the skin, it was found that
so small quantities were sufficient to prevent death as '001 c.c,

1896.] on Immunisation against Serpents' Venom. 119

•0008 c.c, -0005 c.c, and -0004 c.c. (1/1000, 1/1500, 1/2000, and
1/2500 of a c.c, for each kilogramme of the weight of animal ; with
•0003 c.c. (1/333) per kilogramme, however, the animal died. The
antivenene was therefore found to be so powerful as an antidote,
in the conditions of these experiments, that even the 1/2500 part of a
cubic centimetre, equivalent to about the one-hundred-and-fiftieth part
of a minim, acted as an efficient antidote, while even with the one-two-
thousandth part of a cubic centimetre not only was death prevented,
but there was almost no symptom of poisoning produced. In the
experiments of this series with one-and-a-half the minimum-lethal
dose, recovery occurred when the doses of antivenene were '32 c.c,
•3 c.c, '28 c.c, '25 cc, and •24 cc. per kilogramme; but '23 c.c.
and • 2 c.c. failed to prevent death. In the experiments with twice
the minimum-lethal dose, recovery occurred when the doses of anti-
venene were •Sec, •4cc., and ^35 cc. ; but •S cc and '2 cc. failed
to prevent death. In the experiments with thrice the minimum-lethal
dose, a dose capable of producing death in less than two hours, re-
covery occurred when the doses of antivenene were • 7 cc. and • 65 cc. ;
but death occurred with • 6 cc, • 55 c.c, and 5 cc. With four times
the minimum-lethal dose, recovery occurred with 1 • 5 c.c, 1 • 3 cc,
and 1 • 2 cc, and death with 1 cc. With five times the minimum-
lethal dose, recovery occurred with 2 * 5 cc, 2 • 2 c.c, 2 cc, 1 • 8 cc,
and 1 • 5 cc ; but death with 1 * 3 cc. With eight times the minimum-
lethal dose, recovery occurred with 2 • 6 cc. and 2 • 5 cc. ; but death
with 2*4 cc, 2 '3 cc, and 2 cc. And even the enormous dose often
times the minimum-lethal failed to produce death, or any important
symptoms, when it had previously been mixed with 8*5 cc. and
3 • 4 cc. of antivenene for each kilogramme of animal ; and it only
succeeded in producing death, although not until the lapse of several
hours, when the doses of antivenene were 3 • 3 cc, 3 • 2 c.c, • 3 c.c,
and 2 • 5 cc. per kilogramme.

These results show a remarkable, an almost directly proportional
accordance in the increment required in the dose of antivenene for
each increment in the dose of venom. In the diagram, the compara-
tively straight direction of oblique line separating the fatal from the
non-fatal experiments is noteworthy, considering that the conditions
of the exjDcriments, in regard both to the animals and the substances
used, could never be absolutely the same. Indeed, from twice the
minimum-lethal dose of venom upwards, the addition of little more
than • 3 cc. per kilogramme represents the addition in the quantity of
antivenene required for each addition of a minimum-lethal dose of
venom. Apparently the antivenene is able in this proportion to
prevent death from almost any lethal dose of venom, however large
it may be (Fig. 2, overleaf).

These results are in marked contrast with those that occur when
an antidote acts because of its i)hysiological properties, and they
alone suggest that the antidotism is rather the effect of a chemical
than of a physiological reaction. The indications obtained with

120

Professor Thomas B. Eraser

[March 20,

doses of twice the minimum-lethal and upwards cannot, however, be
carried down to the minimum-lethal dose. The quantity of anti-
venene required to prevent death from this dose is much less than
might have been anticipated when the results of experiments with
larger doses are considered. Thus, it appears that while * 35 c.c. of
antivenene per kilogramme is required to prevent death from twice
the minimum-lethal of venom, the minute quantity of the l/2500th
of a c.c, or nearly 1000 times less ("0004 as compared with '35 c.c),
is sufficient to prevent death from a little more than the minimum-
lethal dose of venom. It is apparent that this minute quantity of
antivenene does not render inert the whole of the minimum-lethal
dose. All that is required, in order that the minimum-lethal dose

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should not produce death, being that only a minute portion of it
should be rendered inert ; for, if this dose be the actual minimum-
lethal, the rendering inert of any portion of it, however minute, will
prevent the remainder from causing death.

In the second series, experiments with the antivenene of the horse
have been completed only with one-and-a-half the minimum-lethal
dose of venom. When this dose was injected into the subcutaneous
tissues of one side of the body, and, immediately thereafter, a dose
of antivenene into the subcutaneous tissues of the opposite side, it
was found that antivenene in doses of 3 c.c and 3 * 3 c.c. per kilo-
gramme failed to prevent death, but that 3*5 c.c. and 3*6 c.c. per
kilogramme were able to do so.

In the third series, experiments have been made with the minimum-

1896.] on Immunisation against Serpents* Venom. 121

lethal, one-and-a-half the minimum lethal and twice the minimum-
lethal dose of cobra venom. With the first of these doses, recovery
occurred with '5 c.c, '45 c.c, and '42 c.c. ; but death with *4 c.c,
•3c.c., and '25 c.c. of antivenene, administered thirty minutes before
the venom. With one-and-a-half the minimum-lethal of venom,

2 • 9 c.c. and 2 * 7 c.c. of antivenene were able to prevent death ; while
2*6 c.c, 2*5 c.c, 2*3 c.c, and 2 c.c. each failed in doing so. With
twice the minimum-lethal dose of venom, recovery occurred when the
doses of antivenene were 5 c.c, 4*5 c.c, and 4 c.c; but 8-9 c.c,
3*8 c.c, 3*5 c.c, 2-5 c.c, and 2 c.c were insufficient to prevent death.

In the fourth series, where the results give the truest indications
of the antidotal value of antivenene in the actual treatment of snake-
poisoning, it was found that recovery occurred in the experiments in
which '8 c.c, '7 c.c, and '65 c.c. per kilogramme of antivenene was
injected thirty minutes after an assuredly minimum-lethal dose
( * 00025 per kilo.) of venom ; but that the antivenene was insufficient
in quantity to prevent death when • 6 c.c. or any smaller quantity
was administered. In this series, further, it was found that 3 • 4 c.c.
and 3 • 2 cc per kilogramme of antivenene were sufficient doses to
prevent death after one-and-a-half the minimum-lethal dose of
venom, but that 3 c.c, 2 • 8 c.c, and 2 * 5 cc. per kilogramme were
insufficient. In a corresponding series of experiments made with
the antivenene derived from rabbits which had last received thirty
and fifty times the minimum-lethal dose of cobra venom, it was found
that 5 c.c. per kilogramme of this antivenene was the smallest dose by
which death could be prevented in an animal which had received
twice the minimum-lethal dose of venom thirty minutes previously.

Attention is conspicuously drawn by these facts to the remark-
able difference in the dose of antivenene which is required to prevent
death when it is mixed with the venom before administration, as con-
trasted with the doses required when the two substances have not
previously been mixed together. Eestricting attention to the experi-
ments in each series in which the dose of venom was the same — to
the experiments with one-and-a-half the minimum-lethal dose, for
instance — it a2)pears that in order to prevent death, when this dose
was mixed with antivenene before administration, only *24 c.c. of
antivenene is required ; whereas, when both substances were injected
simultaneously, but under the skin at different parts of the body, the
required dose of antivenene is 3 * 5 cc ; when the antivenene was
injected thirty minutes before the venom, it was 2 • 7 cc. ; and when
the venom was injected thirty minutes before the antivenene, it was

3 • 2 cc per kilogramme.

It is impossible to consider the great difference between the dose
of antivenene recjuired when the two substances, though in each case
simultaneously administered, are, in the one case, mixed together
before injection, and in the other not so mixed, without again having
the suggestion originated that the antidotism is the result of chemical,
and not of physiological reactions.

122 Professor Thomas B. Fraser [March 20,

This suggestion receives a further support from the fact,
observed in several experiments, that the longer before their adminis-
tration the two substances were allowed to remain together after they
had been mixed, the greater is the antidotal efficiency of the aiiti-
venene. Thus, while 1 • 3 c.c. per kilogramme of antivenene, mixed
with five times the minimum-lethal dose of venom, was followed by
death when the two had been mixed together five and also ten minutes
before administration, this mixture was, on the other hand, followed
by recovery when the interval before the administration was extended
to twenty minutes. In order to obtain uniform and comparable
results in the first series of experiments, it was therefore found
necessary to adhere, in all the experiments made with the larger doses
of venom, to a time limitation of not more than ten minutes before
the mixed substances were injected.

I have also administered cobra-antivenene thirty minutes after a
dose one-twelfth larger than the minimum-lethal of the venoms,
respectively, of the Sejiedon hsemacliates, the Crotalus Tiorridus, and
the Diamantina serpent; and the animals experimented on have
recovered when the dose of cobra-antivenene was not smaller than
1 • 5 c.c. per kilogramme. This successful result is all the more
remarkable when the intensely destructive efi'ects produced by even
smaller doses of each, but especially of two, of these venoms is
recollected.

The antivenene derived from rabbits which had been protected to
the extent that they had last received fifteen times the minimum-
lethal dose of the Diamantina venom has also been tested against the
Diamantina venom itself. When the two were administered together,
after having been mixed in vitro, this antivenene in a dose of 0 • 5
(1/20) c.c. per kilogramme was able successfully to antagonise
slightly less than one-and-a-half the minimum-lethal dose of the
venom; but -025 (1/40) c.c. per kilogramme failed to do so.

In the experiments which I have hitherto described, and, indeed,
apparently in all others made in this new subject of serum thera-
peutics, protection has been produced, and the antidotal properties
of the antitoxic blood-serum have been tested, by the subcutaneous,
or, less frequently, by the intravenous injection of the venom or
other toxic substance. No endeavour seens to have been made to
discover how far the same effects, or what effects, may be produced
by stomach administration.

Anticipating that results of an interesting nature might be
obtained by this method of administration, I have adopted it for the
introduction of both antivenene and venom into the body, and the
results have even exceeded my anticipations.

The plan followed was the simple one of mixing the substances,
previously dissolved in water, with a small quantity of milk, and
allowing white rats, which had not received any food for several
hours previously, to drink this milk. In the meantime, I will briefly
describe only those experiments in which antivenene was thus

1896.] on Immunisation against Serpents' Venom. 123

administered, reserving, for a few minutes, a description of the
results that were obtained when the venom itself was used.

The first experiments were made with the object of determining
if, by repeating the process followed in the production of immunity,
with the exceptions that the administrations were by the stomach,
and that antivenene was substituted for venom, an animal could be
protected against the poisonous effects of venom. With this object,
a white rat received on alternate days during several weeks, doses of
antivenene, which were gradually increased from 1 to 10 c.c. per
kilogramme, and then, by subcutaneous injection, one-and-a-half the
minimum-lethal doses of cobra venom ; with the result that death was
not produced. Other white rats received 10 c.c. per kilogramme on
each of four days, and on the fifth day 15 c.c. i3er kilogramme of
antivenene, and still recovery took place when one-and-a-half and
one-and-three-quarters the minimum-lethal dose of venom was injected
under the skin. To other white rats, 10 c.c. and 15 c.c. of antivenene
were given by the stomach, on two successive days, and on the
second day, one-and-a-half the minimum-lethal dose of venom,
and the result also was that death was prevented. It was thus
suggested that a single administration of antivenene might be as
efficacious as a succession of administrations ; and accordingly, the
antidotal efficiency of single doses of 7 and of 10 c.c. per kilogramme
was tested, in some instances three hours, in others two days, and
of 15 c.c. three days before one-and-a-half the minimum-lethal dose
of venom was subcutaneously injected ; and in all cases the animals
recovered. When, however, 5 c.c. j)er kilogramme of antivenene
was thus administered three hours before, and 10 c.c. per kilogramme
three days before, one-and-a-half the minimum-lethal dose of venom,
the animals died.

The experiments have not as yet been carried farther, but I hope
to continue them so that the limits of the antidotal power of the
antivenene, and the duration of the protection after single doses of
antivenene, may be defined. Enough has, however, been done to
prove that the stomach administration of antivenene, equally with its
subcutaneous administration, confers protection against lethal doses
of serpents' venom, and to justify the use of antivenene by the former
and more convenient method for the purpose of securing protection
for, at least, a period of several days after a single administration
of the protecting antidote.

The facts hitherto narrated are sufficient to establish that the
protection acquired by animals as a result of the administration of
venom is not chiefly, or even to any important degree, caused by the
venom having produced a tolerance by accustoming the body, as it
has been expressed, to the presence of the venom — alth<;ugh a certain
degree of this protection may possibly be due to such accustoming —
but rather to the presence in the body, as a result of the introduction
into it of venom, of a definite substance having antivenomous qualities.
Notwithstanding the powerful protective and antidotal action of this

124: Professor Thomas B. Fraser [March 20,

substance (antivenene) against serpents' venom, it is instructive to
find that it is itself almost devoid of any physiological action, for
6ven very large quantities may be injected under the skin without
producing any other physiological reaction than a moderate degree of
irritation in the neighbourhood of the injection. How then are we
to explain the operation of this physiologically inert substance in
protecting an animal against even fifty times the minimum-lethal dose
of venom, or by a single administration of it, in saving an animal
from death after there has been introduced into its body more than
twice the quantity of venom that is required to kill it ? When an
answer has been attempted to be given to this question in discussions
in the wider field of the serum therapeutics which deals with the
toxines of diseases, the answer has been found either in the destruc-
tive power of phagocytes upon microbes and their toxines, or in the
theory that the toxine elaborates from the blood the antidotal anti-
toxine, which, whether thus originated or separately introduced into
the body, confers upon the body a resisting power which enables it
to oppose successfully the injurious action of the toxines.

These answers cannot solve the problem in so far as snake venom
is concerned. Phagocytosis cannot, of course, operate in vitro in
solutions which are free from organised structures. Even when solu-
tions of venom and antivenene, mixed together in vitro, have been
inserted into the body, it is incredible that the increase in the quantity
of antivenene by the 1 /500th part of a cubic centimetre could cause
such an increased proliferation of leucocytes as to prevent a lethal
dose of venom from producing death, whereas a dose only the l/600th
part of a cubic centimetre smaller would be unable to do so. Further,
there is no observable increase of leucocytes when much more than
these infinitesimal quantities of antivenene have been administered to
an animal.

In view of many of the facts that have to-night been stated, the
" resistance of tissues " theory is also untenable. It is opposed, for
instance, by the fact that so great a quantity of antivenene as • 42 c.c,
or nearly ^ of a cubic centimetre, per kilogramme is required to
prevent death when given thirty minutes before a lethal dose of
venom, whereas, for the same dose of venom, only -0004 c.c, or the
l/2500th part of a cubic centimetre, or nearly the 1/lOOOth part of
the former dose, is sufficient, when it is mixed with the venom before
administration, and in circumstances, therefore, which are much less
favourable for the production by the antivenene of this supposed
increase in the resistance of the tissues.

As I have already pointed out, however, a chemical theory,
implying a reaction between antivenene and venom, which results
in a neutralisation of the toxic activities of the venom, is entirely
compatible with the observed facts.

The experiments which I have described to-night indicate that,
with some limitations in the largest quantities, the greater the quantity
of venom that has been introduced into the body in the process of

1896.] on Immunisation against Serpents Venom. 125

producing protection, the greater is the anti-venomous power of the
blood-serum, and therefore the larger is the production of the anti-
venene. While not an actual proof, this circumstance is at the same
time in harmony with the supposition that the antivenene may
actually he a constituent of the venom itself. The difficulties en-
countered in the separation by chemical methods of the several con-
stituents of venom are so great, that it is not probable that the only
proof or disproof of this supposition will soon be obtained by chemical
analysis. Some physiological experiments which I have made seem,
however, to go a long way in supplying the demonstration, which
in the meantime has not been obtained from chemistry.

With the object of determining, in the first place, if the still dis-
puted statement is correct, that serpents' venom is inert, or nearly so,
when introduced into the stomach of an animal, cobra venom was
administered, in a series of gradually increasing doses, to a cat, until
finally it had received a single dose eighty times larger than the
minimum-lethal ; and to each of six white rats, single doses corre-
sponding to 10, 20, 40, 300, 600, and 1000 times the minimum-lethal,
if given by subcutaneous injection. Although no poisonous symptoms
were produced in the animals by even the largest of these enormous
quantities, it was found that the cat had so far been protected, that it
could afterwards receive, by subcutaneous injection, one-and-a-half
the minimum-lethal dose of cobra venom, without any other injury
than some localised irritation at the seat of injection ; and that the
white rat, into whose stomach 1000 times the minimum-lethal dose
had been introduced by one administration, survived perfectly, when
seven days afterwards slightly more than the minimum-lethal dose of
venom was injected under the skin.

It was also found that the blood-serum of the cat was definitely
antivenomous, and the curious further fact was ascertained that her
progeny had acquired protection through the milk supplied by the
protected mother, thus supplying a scientific foundation for a half-
admitted conviction, expressed by Wendell Holmes throughout his
' Romance of Destiny,' in regard to the heroine Elsie Venner.

These significant facts have been extended in a number of other
experiments on white rats. In one group of experiments, each animal
received, by stomach administration, 500 times the minimum-lethal,
if given subcutaneously ; and, as before, no toxic symptoms were
observed. On the day following this administration, three of the
animals received subcutaneously one-and-a-half the minimum-lethal
dose of the same cobra venom, and they all recovered. In one of the
other three animals, however, death was caused by this dose, when it
was injected only three hours after the stomach administration ; in a
second, when this dose was injected two days after the stomach
administration ; and in the third, when nearly twice the minimum-
lethal was injected twenty-four hours after the stomach administration.

In a second group of experiments, a dose of cobra venom equiva-
lent to 1000 times the minimum-lethal by subcutaneous injection was

126 Professor Thomas B. Fraser [March 20,

introduced into the stomach. On several occasions in which this had
been done, an injection under the skin of one-and-a-half the minimum-
lethal dose of venom made, in some experiments, two days, and in
others three days afterwards, resulted in the recovery of the animals.
As was anticipated, this large quantity introduced into the stomach,
conferred immunity against only certain lethal doses of venom, and,
for each lethal dose caj)able of being rendered innocuous, only within
certain definable intervals of time.

The extraordinary result was thus obtained that serpents' venom
introduced into the stomach in large quantity — in a quantity, which,
if injected under the skin, would be sufficient to kill 1000 animals of
the same species and weight — while it failed to produce any definite
symptoms of poisoning, nevertheless produced complete protection
against the lethal effect of doses of venom more than sufficient to kill
the animals. There is a probable significance, further, in the general
resemblance between the results of these experiments and those
already described in which antiveuene, and not venom, was introduced
into the stomach. The bearing of these facts is obvious upon discus-
sions relating to the production of immunisation against the toxines
of diseases and to the origin of the antidotal qualities of the blood-
serum used in their treatment. It is difficult to account for them
otherwise than by supposing that the venom while in the stomach
had been subjected to a process of analysis, by which the constituents
which are poisonous had failed to be absorbed into the blood, or had
been destroyed in the stomach or upper part of the alimentary canal,
while the constituent or constituents which are antivenomous, or
rather antidotal, had passed into the blood, in sufficient quantity to
protect the animals against otherwise lethal administrations of venom.
I confidently anticipate that this natural process of analysis will, by-
and-by, be successfully repeated outside of the body by chemical
methods.

It is further to be observed that by stomach administration a
degree of protection was acquired in a few hours against lethal doses,
such as cannot be attained until after the lapse of several weeks by
the method of injecting under the skin a succession of gradually
increasing doses of venom. In circumstances, which are no doubt
exceptional, the application of this method may therefore acquire
some practical value.

Early this evening, I had occasion to point out that the leading
facts connected with immunisation or protection, now being advanced
as scientific novelties, had apparently been ascertained and practically
applied for centuries by savage and uncultured tribes and sects in
various parts of the world. In regard to the results I have last
described, also, I discover that I have been anticipated by a long-
existing and even now prevailing practice of unlearned savages. I
have found in the Lancet of 1886, an interesting note by Mr. Alford
Bolton, containing the following : " The most deadly snakes here are
the puff-adders, the yellow cobra capellas, the horn-snakes, and the

1896.] on Immunisation against Serpents' Venom. 127

night adders. Whilst frequently hearing of horses and cattle rapidly
succumbing to the bites of these snakes, it appeared strange that the
natives themselves, who mostly ramble about the Veldt almost naked,
seldom or never appeared to suffer any further inconvenience from the
bites of poisonous snakes than would be usual from any accident
which would cause a local inflammation ; and, on close inquiry, I
found that the natives in Bushmanland, Namaqualand, Damaraland,
and the Kalahari, are in the habit of extracting the j)oison-gland
from the suake immediately it is killed, squeezing it into their mouths,
and drinking the secretion, and that they thereby appear to acquire
absolute immunity from the effects of snake-bites." He proceeds to
describe the native treatment of snake-bite, and then adds : " Having
a month ago seen a native named Snellsteve, who is a snake-poison
drinker and collector, put his hand into a box containing two yellow
cobras, and several horn- and night-adders, in doing which he was
severely bitten, and has never since suffered anything more than a
little j)ain, such as might be caused by any trivial mishap, I feel I
can no longer refuse to believe in the efficacy of the snake virus
itself as a remedy against snake-poison." Among several communi-
cations which I have recently received on the subject, is one from
Dr. Knobel, of Pretoria, who writes that when a boy he came into
frequent association with a Bushman shepherd, who informed him
that he had for years been in the habit of swallowing small quantities
of the dried venom-glands of serpents, and he averred that by doing
so he obtained protection against serpents' bites, for he had often
been bitten without any other ill effect than that an irritable wound
was produced. He stated that the swallowed venom of the cobra pro-
duced greater protection than the venoms of less poisonous serpents ;
and that not only was this benefit produced by the swallowing of
venom, but that there w^as also produced an exciting intoxication,
differing from that of Indian hemp in so far that the venom always
produced the same degree of intoxication with a definite quantity,
however frequently it was taken, w^hile the effects of the Indian hemp
were gradually lessened by repetition. Another correspondent. Dr.
Laurence, of Cape Colony, writes that a Kaffir boy, "aged about
twenty-five years, frequently brings me for sale snakes of all kinds.
... I have frequently seen this boy take hold of some most deadly
sna,kes, especially the well-known puff-adder, which he will allow to
bite him with impunity. Yesterday, I obtained from him what he
states as the reason why the poison did not harm him. When a little
boy, while walking in the Veldt, a puff-adder fastened on his leg. He
shook it off, calling to his father, who a few minutes after killed the
puff-adder and removed the poison glands. He then made small
paper pellets and dij^ped them in the poison, and administered one
occasionally to the boy, who stated that that cured him. He ex-
pressed his willingness to let any snake bite him."

Several other letters I have received describe similar events, and
also confirm the statement of Dr. Knobel, that serpents' venom

128 Professor Thomas B. Fraser [March 20,

produces intoxicating effects in man, evidences of which have been ob-
served in many of the experiments made by me on the lower animals.

The results of the experiments in which the venom was introduced
into the stomach, probably also afford an explanation of the protection
enjoyed by certain snake-charmers, as well as by other individuals
who claim to be protected, whether members of special sects or not ;
for although inoculation of the venom is apparently sometimes prac-
tised by them, and protection is no doubt assisted and maintained by
the bites, which with impunity they frequently receive, they are
known also to swallow the venom or the dried poison-glands con-
taining it.

These experiments also seem to throw a new light upon the clearly
established protection possessed by venomous serpents against their
own venom. They suggested the importance of determining if the
blood-serum of venomous serpents contains, as does that of artificially
protected animals, an actual substance possessing antivenomous pro-
perties.

In order to arrive at some definite conclusions on this subject, I
last year obtained from India several living specimens of the Hama-
dryad (Ophiojphagus elaps), a serpent of greater size and more aggres-
sive disposition than the cobra, and reputed to be as deadly as it.
From the blood of several of these serpents a serum was separated,
which when dried gave a product having the same physical characters
as the antivenene from artificially protected animals. It was tested
against cobra venom, both when mixed with rather more than a
minimum-lethal dose, and also when injected thirty minutes after this
lethal dose of cobra venom. In the former case, • 25 c.c. per kilo-
gramme of this natural antivenene prevented death ; and, indeed, so
perfectly antagonised this certainly lethal dose that no decided
symptoms of poisoning were manifested. In the latter case, 5 c.c. per
kilogramme was found to be a sufficient quantity to prevent death. I
hope by-and-by to extend these observations by testing the antidotal
power of this serum against the venom of the actual Hamadryads from
whose blood it had been separated.

A determination of this kind has, however, been made with the
blood-serum and venom of the Australian black snake (Pseudechis
jiorphyriacus), a deadly serpent whose bite produces intense destruc-
tive changes, not only at the place where it has been inflicted, but
also in the blood and in many of the organs of the body. AVhen the
blood-serum and the venom of this serpent were mixed together
outside of the body, and then injected under the skin of a rabbit, it
was found that half a cubic centimetre per kilogramme of the blood-
serum was sufficient to prevent death from rather more than the
minimum-lethal dose of venom.

Notwithstanding the obliging co-operation of the India Office, I
have not yet succeeded in obtaining the blood-serum of the cobra, but
it may safely be anticipated that it also will be found to possess
antivenomous properties.

1896.] on Immunisation against Serpents' Venom. 129

It has thus been shown that venomous serpents themselves possess
a definite substance in the blood-serum which is capable of protect-
ing them against their own venom, and the venom of other serpents.
The results of the experiments made by stomach administration of
venom, supply at the same time an explanation of one, at least, of the
methods by which this substance is introduced into the blood. This
natural antivenene, however, is apparently not so powerfully anti-
dotal as the antivenene obtained by the process of artificial
protection.

The foregoing statements, although referring mainly to observa-
tions on the lower animals, have, probably in every particular, a very
direct bearing upon both the prophylaxis and treatment of snake-
poisoning in man.

Some little consideration of the details of the application of the
antivenene and the employment of auxiliary measures may, however,
be serviceable ; and, equally of practical service, some consideration
of the probable limitations to the capacity of antivenene as an
antidote.

In the meantime, I cannot adduce any actual experience of its use
in human beings, as although a considerable quantity,! both in the
liquid and dry state, was last summer sent to India, and a smaller
quantity to Africa, no opportunity for using it as an antidote has as
yet occurred in the districts to which it had been sent.

But, first, let me say in regard to the altogether unsatisfactory
experience of the use of medicines, ordinarily so-called, that I am not
prepared to take the extreme position that no good can be done by
their employment. While the evidence shows that no one of the very
large number of those that have been recommended as antidotes is
able, in any conditions of administration, to prevent death after the
reception of even the smallest lethal dose of venom, it still may be
that, by the physiological effects which they produce, they may assist
any efficient antidote, such as antivenene, in preventing death ; and
also, by prolonging life, increase the opportunity for a more thorough
use of this antidote. In this category I would especially place
medicines which increase excretion, such as diaphoretics and diuretics ;
many of the rapidly acting stimulants of the circulation, such as
alcohol and the old snake-remedy, ammonia ; and stimulants of
respiration, such as atropine and strychnine, the latter of which is
enthusiastically championed by Dr. A. Mueller, of Sydney. And
not only medicines, but also any measures that are available for
these purposes, including artificial respiration, so distinctly indicated
as a probably valuable therapeutical application in snake- bite by
Fayrer and Brunton, which, though shown by the Indian Snake Com-
mission to be incapable of preventing death when alone trusted to,
was also shown to possess the valuable auxiliary power of prolonging
life.

The first measure, however, that is usually and properly taken in
the treatment of snake-bite, is to restrict, as far as is possible, the

Vol. XV. (No. 90.) k

130 Professor Thomas B. Fraser [March 20,

absorption of the venom into the blood-vessels, from the place into
which it has been injected by the poison-fangs, by separating this
place from the more central parts of the body by a tight ligature.
The efficiency of this measure, preventive rather than curative, is
fortunately aided by the circumstance that snake-bites are most
usually inflicted at parts to which a ligature can conveniently be
applied ; for in fifty-four cases collected by Wall, the part in nearly
89 per cent, of the cases was on the arras or legs. The ligature
having been applied, whenever it is possible to do so, the next
measure to adopt is to open up with a knife, to a considerable depth,
the minute though deep punctures made by the fangs, and then to
apply suction to the wound. Justification is found for this procedure
in the fact, demonstrated by experiment, that notwithstanding the
rapidity with which venom may be absorbed, a portion of it still
remains for a considerable time in the tissues immediately sur-
rounding the wound. This has been clearly demonstrated by both
Kaufmann and Wall. The suction may be produced by the mouth,
and in the absence of more effective apparatus this ready method
would be serviceable, while it is attended with danger to the
operator only in the infrequent occurrence of fissures or abrasions
of the mouth. It is, however, more effectively and without any
risk accomplished by a suction pump, such as the most useful
pump invented by Mr. Andrew Smith, of Cape Colony, which I now
show.

These steps having been taken, antivenene should be injected
into the tissues at and near the wound and, also, under the skin
above the ligature ; and the ligature should not be removed until at
least half an hour after a sufficient quantity of antivenene has been
injected under the skin above it.

But the important question has yet to be answered, What is a
sufficient quantity ? The whole tenor of my remarks to-night has
been to show how necessary it is to bear in mind that there is a
definite relationship between the dose of venom received and the
dose of antivenene required to antagonise it, and that this relation-
ship also varies with the conditions of the administration of the
antivenene, and, especially, with the interval of time that elapses
between the reception of the venom and the administration of the
antivenene.

In snake-bite in man it is impossible to estimate the dose of
venom which has been injected, for the nature of the symptoms in
the patient cannot give the information even approximately. In
searching for a solution of this problem, several facts may be taken
into consideration from which assistance may be obtained. And,
firstly, what is the probable quantity of venom that a serpent injects
into a wound ? Some data for answering this question have, very
kindly, been obtained for me by Brigade-Surgeon Lieut.-Colonel
Cunningham, of Calcutta. Taking nine adult cobras, healthy and
vigorous, he collected from each the venom ejected at a single bite,

1896. ] on Immunisation against Serpents' Venom. 131

dried and weighed each collection separately, and sent me the
weights. They are as follows : —

(1) 0-726 gramme. (4) 0 • 1 14 gramme. (7) 0-239 gramme.

(2) 0-262 „ (5) 0-132 „ (8) 0-306

(3) 0-115 „ (6) 0-113 „ (9) 0-253 „

The total venoms yield an average of 0*255 gramme for each bite ;
but, if the exceptionally large quantity stated in the first figure be
excluded, the average for the remaining eight becomes '195 gramme.
It must also be considered that these quantities were obtained in the
most favourable conditions for securing the total quantity ejected at
a single bite, whereas in actual practice the conditions are less
favourable for the insertion of the total available venom into the
tissues of the victim.

Reverting now to determinations of the minimum-lethal dose for
the lower animals, we find that if the minimum-lethal dose for the
cat be adopted as being the same as that for man, the total quantity
of dry cobra-venom required to kill a man of ten stones weight
would be 'SIT gramme, which is considerably more than the
quantity, judging from the above averages, that a cobra is usually
able to eject during a single bite. It would therefore appear
necessary to assume that the minimum-lethal dose per kilogramme
for man is smaller than for a cat ; but, as it is probably greater
tban for a rabbit, we may for convenience assume that it is twice
that dose. In this case, the smallest quantity required to produce
death in a man of ten stones would be about '0317 gramme, which,
however, seems to be considerably less than the quantity which a
fresh cobra has at its disposal. Applying now the facts that have
been stated in the series of experiments where the smallest quantity
of antivenene required to prevent death when injected thirty minutes
after twice the minimum-lethal dose was determined, it will be
recollected that that quantity is 5 c.c. per kilogramme of animal.
Taking this as a basis for the dose of antivenene, in order to prevent
death in man from the estimated minimum-lethal dose of cobra-
venom, so considerable a quantity as 330 c.c, or about 11^^ ounces,
of antivenene would be required, if the antivenene be injected not
much longer than thirty minutes after the bite had been inflicted.
This, though a large, is by no means an impossible dose, and it could,
without much inconvenience, be introduced under the skin at several
parts of the body.

On the other hand, the estimate which I have adopted of the
minimum-lethal dose for man may be too high a one, and if it should
prove to be nearer that for the rabbit, then the quantity of antivenene
required to prevent death, if administered half an hour after the
snake-bite, would be reduced to about four ounces. It is also to be
recollected that if dry antivenene be used, it may be dissolved in a
much smaller quantity of liquid than is required to restore it to its
original bulk.

K 2

132 Professor Fraser on Serpents' Venom. [March 20,

As to the probability, in a fatal snake-bite, of the quantity of
venom received by the victim being only about, and not much in
excess of, the minimum-lethal dose, it would appear that, in many
cases, even so large a dose is not introduced ; for general experience
indicates that the majority of persons who are bitten actually recover,
whatever treatment is adopted. Sir Joseph Fayrer also shows, in
his classical ' Thanatophidia,' that in 64 per cent, of fatal cases of
snake-bite in India, the victims survived the infliction of the bite for
periods of from three to twenty-four hours ; and this duration of life
implies that the dose of venom received could not have been much
greater than the minimum-lethal.

It must be admitted, however, that even for the minimum-lethal
dose of venom, the quantity of antivenene required to prevent death
in man is probably inconveniently large, especially if, in the treat-
ment, reliance is placed solely upon the administration of antivenene,
to the exclusion of all or several of the auxiliary measures to which
I have referred. It is desirable, also, that the antivenene treatment
should be a practical one, not only for doses of venom which do not
much exceed the minimum-lethal, but also for the considerably
larger doses that are occasionally introduced in snake-bite.

To attain this object, further work is required in order that
there may be obtained an antivenene even more powerful than that
whose antidotal capabilities I have described.

I am not sanguine that this will be accomplished by carrying to
a higher degree the process of artificial protection in animals. A
comparison of the antivenene of rabbits which had last received
thirty times the minimum-lethal dose of cobra venom with that of
other rabbits which had last received fifty times that dose, has shown
that the latter has but little antidotal advantage over the former, and
has suggested that, in the process of artificial protection, the satura-
tion point of the blood for antivenene is reached before the possible
maximum non-fatal dose of venom has been administered.

I would anticipate with more hope the results of endeavours to
separate the true antivenomous principles from the inert constituents
of the blood-serum with which they are mixed ; and although the
required chemical manipulations are attended with many difficulties,
some success has already been obtained in effecting this separation.

In the foregoing remarks, it has, however, been showu that even
with the antivenene whose properties have been described, human
life may be saved in a considerable, if not in a large, proportion of
the cases of snake-bite which would otherwise terminate in death.
The attainment of this result is a satisfactory one ; for the mortality
from snake-bite is large, and is not restricted to the 20,000 deaths
which annually occur in India, but includes additional thousands in
all the tropical and sub-tropical regions of the world.

[T. R. F.]

1896.] New Besearches on Liquid Air. 133

WEEKLY EVENING MEETING,

Friday, March 27, 1896.

Edward Frankland, Esq. D.C.L. LL.D. F.R.S. Vice-President,
in tlie Chair.

Professor Dewar, M.A. LL.D. F.E.S. M.B.L

New Besearches on Liquid Air.

Op all the forms of engineering plant used in low temperature
research, the best and most economical for the production of liquid
air or oxygen is one based on the general plan of the apparatus used
by Pictet in his celebrated experiments on the liquefaction of oxygen
in the year 1878. Instead of using Pictet's combined circuits of
liquid sulphur dioxide and carbon dioxide, maintained in continuous
circulation by means of compression, liquefaction and subsequent
evaporation, it is preferable to select ethylene (after Cailletet and
Wroblewski) for one circuit, and lor the other either nitrous oxide
or, better, carbon dioxide. Further, instead of making highly com-
pressed oxygen to be liquefied by heating potassium chlorate in an
iron bomb directly connected with the refiigerator, it is safer and
more convenient to use gas previously compressed in steel cylinders.
The stopcock that Pictet employed to draw off liquid and produce
sudden expansion, was in his apparatus placed outside the refriger-
ator proper, but it is now placed inside, so as to be kept cool by the
gases undergoing expansion. This improvement was introduced along
with that of isolating the liquid gases by surrounding them with their
own cooled vapour in the apparatus made wholly of copper, described
and figured in the Prcc. Koy. Inst, for 1886. In all continuously
working circuits of liquid gases used in refrigerating apparatus, the
regenerative principle applied to cold, first introduced by Siemens in
1857, and subsequently employed in the freezing machines of Kirk,
Coleman, Solvay, Linde and others, has been adopted. Quite inde-
pendently, Professor Kamerlingh Onnes, of Leiden, has used the re-
generative principle in the construction of the cooling circuits in his
cryogenic laboratory.* Apart, therefore, from important mechanical
details, and the conduct of the general working, nothing new has
been added by any investigator to the principles involved in the con-
struction and use of low temperature apparatus since the year 1878.

♦ See paper by Dr. H. Kamerlingh Onnes, on the " Cryogenic Laboratory
at Leiden, and on the Production of very low Temperatures," Amsterdam
Akademie, 189i.

134 Professor Deivar [Marcli 27,

Detailed drawings of the Royal Institution refrigerating plant now
in use have not been published, simply because changes are constantly
being made in the apparatus. Science derives no benefit from the
description of transitional apparatus when there is no secret about
the working process and how to carry it into effect. The Phil. Mag.
of February, 1895, contains a fantastic claim put forward by Professor
Olszewski, of Cracow, that because he used in 1890 a steel tube com-
bined with a stopcock to draw off liquid oxygen, he had taught the
world, to use his own language, " the method of getting large
quantities of liquid gases." In addition the Professor alleges, four
years after the event, that the experiments made at the Royal Insti-
tution are chiefly borrowed from Cracow, and that he is entitled to
the credit of all low temperature research. As to such chiims, one
can only wonder at the meagre additions to knowledge that in our
time are unhesitatingly brought forward as original, and more
especially that scientific men could be got to give them any currency
in this country. Such persons should read the late Professor Wro-
blewski's pamphlet, entitled ' Comment I'air a ete liquetie,'* and
make themselves generally acquainted with the work of this most
remarkable man before coming to hasty conclusions on claims of
priority brought forward by his some time colleague.

Liquefying Apimratus. — A laboratory apparatus for the production
of liquid oxygen and other gases is represented in section (Fig. 1).
"With this simple machine, 100 c.c. of liquid oxygen can readily be
obtained, the cooling agent being carbon dioxide, at the temperature
of —79°. If liquid air has to be made by this apparatus, then the
carbon'c acid must be kept under exhaustion of about 1 inch of mer-
cury pressure, so as to begin with a temperature of— 115°. Under
such conditions the yield of the liquid gases is much greater. The
gaseous oxygen, cooled before expansion by passing through a spiral
of copper tube immersed in solid carbon dioxide, passes through a
fine screw stopcock under a pressure of 100 atmos., and thence back-
wards over the coils of pipe. The liquid oxygen begins to drop in
about a quarter of an hour from starting. The general arrangement
of the circuits will be easily understood from the se-tional drawing.
The pressure in the oxygen cylinders at starting is generally about
150 atmos., and the best results are got by working down to about
100. If a small compressor is combined with the apparatus the
liquefaction can go on continuously. This little apparatus will enable
liquid oxygen or air to be used for demonstration and research in all
laboratories.

Vacuum Vessels. — It has been shown in previous papers t that a
good exhaustion reduces the influx of heat to one-fifth part of what is
conveyed when the annular space in such double-walled vacuum
vessels is filled with air. If the interior walls are silvered, or excess

* Pfiris, Libraire du Luxembourg, 1885.

t " On Liquid Atmospheric Air," Proc. Roy. Inst. 1893; "Scientific Uses of
Liquid Air," ibid. 1894.

1896.] on New Besearches on Liquid Air. 135

of mercury is left in the vessel, the influx of heat is diminished to
one-sixth part of the amount entering without the metallic coating.
The total effect of the high vacuum and silvering is to reduce the
ingoing heat to one-thirtieth part, or, roughly, 3J per cent.. Vessels
constructed with three dry air spaces only reduced the influx of heat
to 35 per cent. An ordinary mercury vacuum vessel is therefore ten
times more economical for storing liquid air, apart from considerations
of manij)ulation, than a triple annular spaced air vessel. It has been
suggested that the metallic coating of mercury does no good, because
Pictet has found that all kinds of matter become transparent to heat
at low temperatures. The results above mentioned dispose of this
assumption, and direct experiment proves that no increase in the
transparency of glass to thermal radiation is effected by cooling it to
the boiling point of air.*

An ocular demonstration of the correctness of the above state-
ments can easily be shown by mounting on the same stem three
similar double-walled test tubes, two of which have been simul-
taneously exhausted and sealed off from the air pump together, while
the third is left full of air. One of the vacuum test tubes is conted
with silver in the interior. The apparatus is shown in Fig. 2. A has
the annular space filled with air ; B and C are exhausted, C being
coated with silver. On filling liquid ethylene to the same height into
each vessel, and inserting corks with similar gas jets and igniting the
escaping gas, the rehitive volumes of the flames is roughly proj^or
tional to the influx of heat, and resembles what is shown in the drawing.
It is satisfactory to have independent corroboration of the advantages
of the use of vacuum vessels, and this may be found in a paper by
Professor Kamerlingh Onnes, of Leiden, communicated to the Am-
sterdam Academy of Sciences, 1896, entitled ' Kemarks on the Lique-
faction of Hydrogen, on Thermodynamical Similarity, and in the Use
of Vacuum Vessels,' in which he says: — "In the same degree as it
becomes of more importance to effectuate adiabatic processes at very
low temperatures, the importance of the vacuum vessels of Dewar will
increase. It seems to me that they are the most important addition
since 1883 to the appliances for low temperature research." ..." It
is a rejoicing prospect that practical engineers will doubtless feel the
want of such non-conducting mantles. For as soon as this stage is

* At a meeting of the French Academy in 1895 a paper by M. Solvay of
Brussels was read, in which my 1892 device of vacuum vessels was attributed to
M. Cailletet, and tacitly accepted by him ! In 1875 I had already used a highly
exhaustive vessel, of similar shape to the vacuous test tube, in calorimetric ex-
periments. See paper on '* The Physical Constants of Hydrogsniura," Trans.
Koy. Soc. Ed. vol. xxvii. Even as late as April 1896, Professor Tilden, D.Sc.
F.R.S, of the Koyal College of Science, in a paper entitled " L'Appareil du
Dr. Hampson pour la Liquefaction de I'air et des gas," communicated to the
' Revue Ge'ne'rale des Sciences,' thought proper to write as follows : " Un manchon
de verre, dans lequel on a fait le vide (manchon semblable a ceux de'crits par
Cailletet ou Dewar)." Where did Professor Tilden find Cailletet's description
of a vacuum vessel? This is not the only statement in the paper requiring
correction.

136 Professor Dewar [March 27,

reached, numbers of heads and hands are disposed to take over the
problem from the scientific researcher."

Solid Air. — As Professor Olszewski has recently alleged that
air does not solidify at the lowest pressures,* the author's former
experiments were repeated on a larger scale. If a litre of liquid
air is placed in a globular silvered vacuum vessel and subjected to
exhaustion, as much as half a litre of solid air can be obtained
and maintained in this condition for half an hour. At first the
solid is a stiff, transparent jelly, which, when examined in the
magnetic field, has the liquid oxygen drawn out of it to the poles.
This proves tLat solid air is a nitrogen-jelly containing liquid
oxygen. This statement was made in a paper " On the Refraction
and Dispersion of Liquid Oxygen, and the AbsorjDtion Spectrum of
Liquid Air" (Professors Liveing and Dewar), published in the
Phil. Mag. for September 1895, yet Professor Olszewski, in 1896t
is declaring " that Professor Dewar has stated that liquid air
solidifies as such, the solid product containing a slightly smaller
percentage of nitrogen than is present in the atmosphere. My
experiments have proved this statement to be incorrect." The Cracow
professor may well have the satisfaction of correcting a statement
which was never made by me. He seems also to forget that in
1893, Proc. Roy. Inst. Lecture on Liquid Air, it is distinctly stated
that " all attempts to solidify oxygen by its own evaporation have
failed." Solid air can only be examined in a vacuum or in an
atmosphere of hydrogen, because it instantly melts on exposure to
air cooled to the temperature of its boiling point, giving rise to
the liquefaction of an additional quantity of air. It is strange to see
a mass of solid air melting in contact with the atmosphere, and
all the time welling up like a kind of fountain. The apparatus
shown in Fig. 3 is well adapted for showing the direct liquefaction
of the air of a room and its solidification. A large vacuum vessel G,
is mounted on a brass stand containing another smaller vessel B of
the same kind. By means of the two cocks C and D, either the large
vessel G or the bulb B can be connected to the air pump circuit.
Liquid oxygen is placed in A, which can, by opening the stopcock D,
be cooled to —210° by exhaustion. If the stopcock C is shut and a
barometric gage is joined on at F, the dropping of the liquid air from
the outside of A will go on even at as low a pressure as 4 in. of mer-
cury ; w^hich is equivalent to saying that this apparatus would
liquefy air if taken by a balloon ten miles high. If F is now opened,
giving a supply of air at atmospheric pressure, the cup B soon fills
with liquid air. Unless the air supply is passed over soda lime and
strong sulphuric, the liquid is always turbid from the presence of
ice crystals and solid carbonic acid. Now on shutting F and
opening C, the air in B is placed under exhaustion and soon solidifies
to a jelly-like mass. When the vacuum is about 14 mm. then the
temperature of the solid air is — 232° by the platinum resistance

* rhih Mag. Ftbniary 1895. f See ' Nature,' Aug. 20, p. 378.

1896.] on New Researches on Liquid Air. 137

thermometer, or — 216° C. On allowing the air to enter, the solid
instantly melts and more liquid air is formed. The same experi-
ment may be repeated many times by simply opening and shutting
the stopcocks. When the liquid air loses too much nitrogen, then it
no longer solidifies. This apparatus may be used to show that when
liquid air is running freely into B, liquefaction is instantly arrested
l)y allowing hydrogen to enter instead of air.

Samples of Air Liquefied in Sealed FlasJcs. — In a paper " On the
relative behaviour of chemically prepared and of atmospheric nitro-
gen," communicated to the Chemical Society in December 1894, the
plan of manipulating such samples was described. The arrangement
shown in Fig. 4 illustrates how oxygen in A under 0*21 of an atmos.
pressure, and nitrogen in B under 0 • 79 of an atmos., can be compared
as to the first appearance of liquefaction in each, and finally as to their
respective tensions when the temperature is as low as that of solid
nitrogen. The flasks A and B have a capacity of more than a litre.
Each has a manometer sealed on, and in each phosphoric anhydride
is inserted to secure dryness. A large vacuum vessel C holds the
liquid air, which is gradually lowered in temperature by boiling
under exhaustion. The moment liquefaction takes place, the tubes
D', D" begin to show liquid. These tubes must be drawn fine at the
end when accurate observations are being made. In the same manner
two oxygen flasks were compared. One filled with gas made from
fused chlorate of potash, contained in a side tube sealed on to the
flask. The other was treated in the same way, only the chlorate had
a little peroxide of manganese added. The former gave perfectly
clear blue liquid oxygen, the latter was turbid from solid chlorine.
Two flasks of dry air that had stood over phosphoric anhydride were
liquefied side by side, the only difierence between the samples being
that one was free from carbonic acid. The one gave a liquid that
was perfectly clear, the other was turbid from the 0 • 04 per cent, of
carbon dioxide.

The temperature was lowered by exhaustion until samples of
liquid air from two flasks placed side by side as in Fig. 4 became
solid. The flasks were then sealed off" for the purpose of examining
the composition of the air that had not been condensed. The one
sample contained oxygen, 21*19 per cent., and the other 20*7 per
cent. This is an additional proof to the one previously given that,
substantially, the oxygen and nitrogen in air liquefy simultaneously,
even under gradually diminishing pressure, and that in these ex-
periments all the known constituents of air are condensed together.
These results finally disprove the view expressed in ' A System of
Inorganic Chemistry,' * by Professor Ramsay, where he says : " Air
has been liquefied by cooling to —192°, but as oxygen and nitrogen
have not the same boiling points, the less volatile oxygen doubtless
liquefies first." My old experiments! showed that the substance
now known as argon became solid before nitrogen, but chemical

* 1891, p. 70. t See Proc. Chem. Soc. Dec. 1894.

138

Professor Deivar

[March 27,

nitrogen and air nitrogen, with its 0 • 1 per cent, of argon, behaved in
substantially the same way on liquefaction.

Liquid Nitric Oxide. — Great interest attaches to the behaviour of
nitric oxide at low temperatures. Professor Olszewski has examined
the liquid and describes it as colourless. Samples of nitric oxide
have been prepared in different ways. These have been transferred
to liquefaction flasks, where they were left in contact with anhydrous
potash, sulphuric acid alone, a mixture of sulphate of aniline and
sulphuric acid, or phosphoric acid, for many days before use. Each
of the samples, when cooled, gave a nearly white solid, melting into
a blue liquid. The colour is more marked at the melting point than
at the boiling point. Liquid nitric oxide is not magnetic ; neither is
the solid phosphorescent. Colour in the oxides of nitrogen evidently
begins with the second oxide. Solid nitric oxide does not show any
chemical action when j^laced in contact with liquid oxygen, provided
the tube containing it is completely immersed ; but if the tube full
of liquid oxygen is lifted into the air, almost instantly a violent
explosion takes place.

Specific Gravities tahen in Liquid Oxygen. — In a good vacuum
vessel specific gravities may be taken in liquid oxygen with as great
ease as in water. The shape of the vacuum vessel which works best is
shown in Fig. 4. It must contain excess of mercury and be thoroughly
boiled out, so that the inner vessel becomes completely coated with a
mercury mirror as soon as the liquid oxygen is filled in. Instead of a
mercury vacuum, the interior may be silvered and highly exhausted
by a Sprengel pump. The flasks must also be thoroughly clean and
free from dust, otherwise the liquid oxygen will not remain tranquil.
Any superheating is prevented by inserting a long narrow piece of
wood for a moment before the final weighing.

Some twenty substances were weighed in liquid oxygen,* and the
apparent relative density of the oxygen determined. The results
were then corrected, using Fizeau's values for the variation of the
coefficient of expansion of the solids employed, and thereby the
real density of liquid oxygen calculated. The resulting value was
1'1375, bar. 766-5, in the case of such different substances as
cadmium, silver, lead, copper, silver iodide, calc-spar, rock crystal.
The following table sives some of the observations : —

Mean Cubical Coefficient of Expansion

Apparent Density of

Real Density of Liquid

between 15° C.-183° G.

Liquid Oxj^gen.

Oxygen.

Cadmium, 7986x10"^.. ..

1-1188

1-1359

Lead, 7892 „ .. ..

1-1197

1-1367

Copper, 4266 „

1-1278

1-1370

Silver, 5185 „ .. ..

1-1278

11385

Calc-spar, 1123 „ .. ..

11352

1-1376

Eock crystal, 2769

1-1316

1-1376

Silver Iodide, 0189 „ .. ..

1-1372

1-1376

♦ The liquid oxygen might possibly contain a small proportion of nitrogen.

1896.] on New Besearches on Liquid Air. 139

Direct determinations with an exhausted glass cylindrical vessel
displacing about 22 c.c. gave 1-1378. Fizeau's parabolic law for
the variation of the coefficient of expansion holds down to —183^.
The solid which showed the greatest contraction was a block of
compressed iodine ; the one that contracted least being a compressed
cylinder of silver iodide. Wroblewski gave the density of liquid
oxygen at the boiling point as 1*168, whereas Olszewski found 1 • 124.
The variation of density is about +0'0012, for 20 mm. barometric
prc>:sure. Much work requires to be done in the accurate deter-
mination of the physical constants of liquid gases.

Liquid Air. — A large silver ball weighed in liquid air gave the
density of the latter as 0-910, and the corresponding density of
nitrogen at its boiling point 0 - 850. It is difficult to be quite certain
that the constituents of liquid air are in the same proportion as the
gaseous ones, so that further experiments must be made. Liquid air
kept in a silvered vacuum vessel gradually rises in boiling point from
the instant of its collection, the rate of increase during the first hour
being nearly directly proportional to the time. As the increase
amounted to 1° in ten minutes, the boiling point of oxygen ought to
have been reached within two hours. The density of liquid air,
however, does not reach that of pure oxygen even after thirty hours'
storage. The large apparatus of the Eoyal Institution for air lique-
faction can be arranged to deliver liquid air containing 49 per cent,
of oxygen, which gives off gas containing 20 per cent, of oxygen,
rising after six hours to 72-6 per cent.

Combustion in Liquid Oxygen. — A small ignited jet of hydrogen
burns continuously below the surface of liquid oxygen, all the water
produced being carried away as snow. There is a considerable
amount of ozone formed, which concentrates as the liquid oxygen
evaporates. In the same way graphite or diamond, when projjerly
ignited, burns continuously on the surface of liquid oxygen, pro-
ducing solid carbonic acid and generating ozone. If liquid oxygen
is absorbed in wood charcoal, or cotton-wool, and a part of the body
heated to redness, combustion can start with explosive violence.

Gas Jets containing Liquid. — The experiments of Joule and Thom-
son and Reguault on the temperature of gas jets issuing under low
pressures are well known. The following observations refer to the
pressure required to produce a lowering of temperature sufficient to
yield liquid in the gas jet.

The apparatus used in the study of highly compressed gas jets is
represented in Fig. 2 ; where C is a vacuum tube which holds a coil
of pipe about 5 mm. in diameter surrounded with carbon dioxide or
liquid air for cooling the gas before expansion, and A is a small
hole in the silver or copper tube about i mm. in diameter, which
takes the place of a stopcock. When carbon dioxide gas at a pressure
of 30 or 40 atmos. is expanded through such an aperture, liquid can
be seen where the jet impinges on the wall of the vacuum tube, along
with a considerable amount of solid. If oxygen gas escaj^es from the
gmall hole at the pressure of 100 atmos. having been cooled previously

140 Professor T)ewar [March 27,

to —79° in the vessel C, a liquid jet is just visible. It is interest-
ing to note, in passing, that Pictet could get no liquid oxygen jet
below 270 atmos. This was due to his stopcock being massive and
outside the refrigerator. If the oxygen is replaced by air, no liquid
jet can be seen until the pressure is 180 atmos., but on raising the
pressure to 300 atmos. the liquid air collected well from the simple
nozzle. If the carbon dioxide is cooled by exhaustion (to about 1 inch
pressure) or — 115°, then liquid air can easily be collected in the small
vacuum vessel D, or if the air pressure is raised above 200 atmos.,
keeping the cooling at —79° as before.* The chief difficulty is in
collecting the liquid, owing to the rapid current of gas. The amount
of liquid in the gas jet is small, and its collection is greatly facilitated
by directing the spray on a part of the metallic tube above the little
hole, or by increasing the resistance to the escaping gas by placing
some few turns of the tube, like B in the figure, in the upper portion
of the vacuum tube, or generally by pushing in more tube in any form.
A vacuum vessel shaped like an egg-glass also works well. This prac-
tically economises the cool gas which is escaping to reduce the tem-
perature of the gas before expansion, or, in other words, it is the cold
regenerative principle. Coleman pointed out long ago that his air
machine could be adapted to deliver air at as low a temperature as
has yet been produced in physical research. Both Solvay and Linde
have taken patents for the production of liquid air by the application
of cold regeneration, but the latter has the credit of having succeeded
in constructing an industrial apparatus that is lowered in tempera-
ture to —140°, or to the critical point of air, in about 15 hours,
and from which liquid air containing 70 per cent, oxygen is collected
after that time.

For better isolation, the pipe can be rolled between two vacuum
tubes, the outer one being about 9 inches long and IJ inch diameter,
as shown in Fig. 3. The aperture in the metal pipe has a little piece
of glass tube over it, which helps the collection of the liquid. With
such a simple apparatus, and an air supply at 200 atmos. with no
previous cooling, liquid air begins to collect in about five minutes, but
the liquid jet can be seen in between two and three minutes. It is
not advisable to work below 100 atmos.

In Fig. 4 the metallic tube in the vacuum vessel is placed in
horizontal rings, leaving a central tube to allow the glass tube C to
pass, which is used to cool bodies or examine gases under compression.
The inner tube can be filled for an inch with liquid air under a
pressure of 60 atmos. in about three minutes. Generally, in the
experiments, about ^ to 4 cubic feet of air passes through the dif-
ferent sized needle holes per minute when the pressure is about
200 atmos. As the small hole is apt to get stopped, for general

* The liquefaction is takin*? place in this condition at 1| times the critical
temperature. Hydrogen similarly expanded at the melting point of air
(— 2H° G.) behaves exactly in the same way.

1896.]

on New Researches on Liquid Air.

141

working it is better to use a needlo stopcock, worked from the outside
by a screw passing through the middle of the coil of pipe.

In testing the individual coils as to the amount of air passed per
minute under different pressures, the arrangement of apparatus shown
in the Plate 7 was used.

A is a bottle of compressed air, to which the copper pipe B is
attached. This coiled pipe first passes through the vessel C con-
taining water, in order to equalise the temperature, and then through
the cork D into the glass vacuum vessel E, when it is led by a large
number of convolutions to the bottom, terminating in a minute pin-
hole valve F. The released air passes from F right up through the
coils and out of the vent by the copper tube G, which in its turn
passes through a vessel H similar in its object to C, and is then
conducted to a measuring meter Z J.

The following table gives the results of a series of experiments
made on one coil as to the rate of discharge of air at different
pressures : —

Pressure in Atmo-
spheres.

65
105
155
198
210
250
287
290

Cubic Feet per Minute

Measured under Atmosphere

at 15°.

0 22
0-42
0-63
0-79
0-84
1-00
115
1-18

The results show that the rate of air discharge through a fine
aperture is directly proportionate to the pressure, or the velocity
with which the gas on the high-pressure side enters the orifice, is
independent of the density. Actual measurements of the size of the
needle-hole resulted in proving that the real velocity of the air
entering the aperture on the high-pressure side was about 500 feet
per second. In all these experiments the temperature of the coil was
not allowed to get so low as to produce any visible trace of conden-
sation in the air jet. Just before liquefaction the rate of dischart^e
of air through the same aperture may be doubled, the pressure re-
maining steady, owing to change in the viscosity of the gas and other
actions taking place at low temperatures. The above measurements
can only be regarded as representing the general working of such
regenerating coils.

A double coil of pipe has advantages in the conduct of some
experiments. The efficiency is small, not exceeding the liquefaction
of 2 to 5 per cent, of the air passing, but it is a quick method of

142 Professor Dewar [Marcli 27,

reacliing low temperatures, and easy to use for cooling tubes and col-
lecting a few hundred c.c. of liquid air, especially if the compressed
air is delivered at the temperature of — 79° before expansion. With
larger vacuum vessels and larger regenerating coils no doubt the
yield of liquid could be increased. The liquid air resulting from
the use of this form of apparatus contains about 50 per cent, of
oxygen. If the air is cooled with solid carbonic acid previous to its
reaching the vacuum tube coil of pipe, the only change is to reduce
the percentage of oxygen to 40. Successive samples of liquid
taken during the working had nearly the same composition. If
the arrangement shown in Fig. 2 is used, with silver tube, about
-j?^ inch bore, and a foot or two coiled in upper part of the vacuum
vessel, liquid air containing 25 per cent, of oxygen is obtained.
On the other hand, the percentage of oxygen can be increased by a
slight change in the mode of working.

In the above experiments air is taken at the ordinary temperature,
which is a little above twice its critical temperature, and is partially
transformed in a period of time which, in my experiments, has never
exceeded ten minutes, simply and expeditiously into the liquid state
at its boiling point, — 194°, or a fall of more than 200° has been
effected in this short period of time.

Experiments on Hydrogen. — Wroblewski made the first conclusive
experiments on the liquefaction of hydrogen in January 1884. He
found that the gas cooled in a tube to the boiling point of oxygen, and
expanded quickly from 100 to 1 atmos., showed the same appearance
of sudden ebullition as Cailletet had seen in his early oxygen experi-
ments. No sooner had the announcement been made than Olszewski
confirmed the result by expanding hydrogen from 190 atmos. pre-
viously cooled with oxygen and nitrogen boiling in vacuo. Olszewski
declared in 1884 that he saw colourless drops, and by partial expansion
to 40 atmos. the liquid hydrogen was seen by him running down the
tube. Wroblewski could not confirm these results, his hydrogen being
always what he called a " liquide dynamiqiie." He proposed to get
" static " liquid hydrogen by the use of hydrogen gas as a cooling
agent. Professor Ramsay, in his ' System of Inorganic Chemistry,'
published long after the early experiments of Pictet, Cailletet,
Wroblewski and Olszewski on the liquefaction of hydrogen had been
made, sums up the position of the hydrogen question in 1891 as
follows (p. 28) : — " It has never been condensed to the solid or liquid
states. Cailletet, and also Pictet, who claim to have condensed it by
cooling it to a very low temperature, and at the same time strongly
compressing it, had in their hands impure gas. Its critical tem-
perature, above which it cannot appear as liquid, is probably not
above — 230°." It has to be remembered that 7 per cent, of air by
volume in hydrogen means about 50 per cent, by weight of the mixed
gases. Even 1 per cent, by volume in hydrogen is equivalent to
some 13 per cent, by weight.

The following table gives the theoretical temperatures reached for

1896.]

on New Besearches on Liquid Air.

143

an instant during the adiabatic expansion of hydrogen under different
conditions : —

Initial Pressure Atmospheres.

Initial Temperature.

Theoretical Final
Temperature (Absolute).

500 (Pictet)

300 (Cailletet)

100 (Wroblewski)

180 (Olszewski)

100

200

500

O

-130
0
-184
-210
-200
-200
-200

0

25

52

24

14

19-5

15-7

12-7

The calculations show that little is gained by the use of high
pressures. The important inference to be drawn from the figures is
to start with as low a temperature as possible.

From 1884 until his death, in the year 1888, Wroblewski devoted
his time to a laborious research on the isothermals of hydrogen at
low temperatures. The data thus arrived at enabled him, by the
use of Van der Waal's formulae, to define the critical constants of
hydrogen, its boiling point, density, &c., and the subsequent experi-
ments of Olszewski have simply cimfirmed the general accuracy of
Wroblewski's results. Wroblewski's critical constants of hydrogen
are given in the following table : —

Critical temperature —240°

„ pressure 13-3 atmos.

„ density 0-027

Boiling point -250°

Density at boiling point * 0-063

In a paper published in the Phil. Mag. September 1884, " On the
Liquefaction of Oxygen and the Critical Volumes of Fluids," the sug-
gestion was made that the critical pressure of hydrogen was wrong,
and that instead of being 99 atmos. (as deduced by Sarrau from
Amagat's isothermals) the gas had probably an abnormally low value
for this constant. This view was substantially confirmed by Wro-
blewski finding a critical pressure of 13*3 atmos., or about one-fourth
that of oxygen. The ' Chemical News ' (September 7, 1894) contains
an account of the stage the author's hydrogen experiments had reached
at that date. The object was to collect liquid hydrogen at its boiling
point in an open vacuum vessel, which is a much more difficult
problem than seeing the liquid in a glass tube under pressure and at
a higher temperature. In order to raise the critical point of hydrogen
to about — 200°, from 2 to 5 per cent, of nitrogen or air was mixed
with it. This is simply making an artificial gas containing a large

* It is probahle that the real density of boiling liquid hydrogen may lie
between 0-12 and 0-18.

144 Professor Deivar [March 27,

proportion of hydrogen, which is capable of liquefaction by the use
of liquid air. The results are summed up in the following extract
from the paper : — " One thing can, however, be proved by the use of
the gaseous mixture of hydrogen and nitrogen, viz. that by subjecting
it to a high compression at a temperature of — 200°, and expanding
the resulting liquid into air, a much lower temperature than any-
thing that has been recorded up to the present time can be reached.
This is proved by the fact that such a mixed gas gives, under the
conditions, a paste or jelly of solid nitrogen, evidently giving off
hydrogen because the gas coming off burns fiercely. Even when
hydrogen containing only some 2 to 5 per cent, of air is similarly
treated the result is a white, solid matter (solid air) along with a
clear liquid of low density, which is so exceedingly volatile that no
known device for collecting has been successful." *

In Professor Olszewski's paper " On the Liquefaction of Gas," f
after detailing the results of his hydrogen experiments, he says : —
" The reason for which it has not hitherto been possible to liquefy
hydrogen in a static state is, that there exists no gas having a density
between that of hydrogen and nitrogen, and which might be, for
instance, 7 — 10 (H = 1). Such a gas would be liquefied by means
of liquid oxygen or air as cooling agent, and afterwards used as a
recognised menstruum in the liquefaction of hydrogen. Science
will probably have to wait a very long time before this sug-
gestion of how to get " static " liquid hydrogen is realised. The
proposal Wroblewski made in 1884 of using the expansion of hydro-
gen as a cooling agent to effect the change of state, is far more direct
and practicable.

Liquid Hydrogen Jet and Solid Hydrogen. — Hydrogen, cooled to
~ 194° (80° abst. t.), the boiling point of air, is still at a temperature
which is two and a half times its critical temperature, and its direct
liquefaction at this point would be comparable to that of air taken at
60°, and liquefied by the apparatus just described. In other words, it
is more difficult to liquefy hydrogen (assuming it to be supplied at
the temperature of boiling air) than it is to produce liquid air start-
ing from the ordinary atmospheric conditions. Now, air supplied at
such a high temperature greatly increases the difficulty and the time
required for liquefaction. Still it can be done, even with the air
supply at 100°, in the course of seven minutes, and this is the best
proof that hydrogen, if placed under really analogous conditions,
namely at —194° must also liquefy with the same form of apparatus.
It is almost needless to say that hydrogen under high compression
at the temperature of 15° C. passed through such a regenerating coil,
produced no lowering of temperature. Hydrogen cooled to — 200°
was forced through a fine nozzle under 140 atmos. pressure, and yet

* The compressed gas mixture at above —210° was expanded into a large
cooled vacuum vessel.
t Phil. Mag. 1895.

^

Fig. 1.

Labokatoey Liquefaction Apparatus for the production of Liquid Oxygen, &c.

A, air or oxygen iulet ; B, carbou dioxide iulet ; C, carbon dioxide valve ;
D, regenerator coils; F, air or oxygen expansion valve; G, vacuum vessel
with liquid oxygen ; H, carbon dioxide and air outlet ; O, air coil ; f^, carbou
dioxide coil.

Fig. 2.
Liquid Ethylene Flame Calorimeter.

-to rv.^^^.

Fig. 3.

Lecture Apparatus for Projecting the Liquefaction of Air
AT Atmospheric Pressure, and its Solidification.

Fig. 4.

Plan of comparing Eelative Temperatures op Liquefaction and
Small Vapour Pressures.

Fig. 5.
Specific Gravity A^acuum Globe.

^

s

fe

S)

^

h

INLZT

L^B

I

Fig. 6.
Different Arrangements of Regenerating Coils,

Ph

iX!

Fig. 8.
Apparattts used in the production of tpie Liquid Hydrogen Jet.

1896.] on New Besearches on Liquid Air. 145

no liquid jet could be seen. If the hydrogen contained a few per
cent, of oxygen the gas jet was visible, and the liquid collected, which
was chiefly oxygen, contained hydrogen in solution, the gas given off
for some time being explosive.

If, however, hydrogen, cooled by a bath of boiling air, is allowed
to expand at 200 atmos. over a regenerative coil previously cooled to
the same temperature, and similar in construction to that shown in
Fig. 8,* a liquid jet can be seen after the circulation has continued
for a few minutes, along with a liquid which is in rapid rotation in
the lower part of the vacuum vessel. The liquid did not accumulate,
owing to its low specific gravity and the rapid current of gas.
These difficulties will be overcome by the use of a differently shaped
vacuum vessel, and by better isolation. That liquid hydrogen can be
collected and manipulated in vacuum vessels of proper construc-
tion cannot be doubted. The liquid jet can be used in the meantime
(until special apj)aratus is completed for its collection) as a cooling
agent, like the spray of liquid air obtained under similar circum-
stances, and this being practicable, the only difficulty is one of
expense. In order to test, in the first instance, what the hydrogen
jet could do in the production of lower temperatures, liquid air and
oxygen were placed in the lower part of the vacuum tube just
covering the jet. The result was that in a few minutes about
50 c.c. of the respective liquids were transformed into hard white
solids resembling avalanche snow, quite different in appearance from
the jelly-like mass of solid air got by the use of the air pump.
The solid oxygen had a pale, bluish colour, showing by reflection
all the absorption bands of the liquid. The temperatures reached,
and other matters, will be dealt with in a separate communication.
When the hydrogen jet was produced under the surface of liquid air,
the upper part of the fluid seemed to become specifically lighter, as
a well marked line of separation could be seen travelling downwards.
This appearance is no doubt due in part to the greater volatility of
the nitrogen and the considerable diiference in density between liquid
oxygen and nitrogen. In a short time solid pieces of air floated about,
and the liquid subsequently falling below the level of the jet, hydrogen
now issued into a gaseous atmosphere containing air, which froze solid
all round the jet. There is no reason why a spray of liquid hydrogen
at its boiling point in an open vacuum vessel should not be used as a
cooling agent, in order to study the properties of matter at some 20*^
or 30° above the absolute zero.

Fluorine. — This is the only widely distributed element that has
not been liquefied. Some years ago Wallach and Hensler pointed out
that an examination of the boiling points of substituted halogen organic
compounds led to the conclusion that, although the atomic weight
of fluorine is nineteen times that of hydrogen, yet it must in the

* In the figure, A represents one of the hydros^en cylinders; B and C,
vacuum vessels containing carbonic acid under exhaustion and liquid air re-
spectively; D, regenerating coil; G, pin-hole nozzle ; F, valve.

Vol. XV. (No. 90.) l

146 New BesearcJies on Liquid Air. [March 27,

free state approacli hydrogen in volatility. This view is confirmed
by the atomic refraction which Gladstone showed was 0*8 that of
hydrogen, and from which we may infer that the critical pressure of
fluorine is relatively small like hydrogen.* If the chemical energy
of fluorine at low temperatures is abolished like that of other active
substances, then some kind of glass or other transparent material
could be employed in the form of a tube, and its liquefaction achieved
by the use of hydrogen as a cooling agent. In any case a platinum
vessel could be arranged to test whether fluorine resists being liquefied
at the temperature of solid air, and this simple experiment, even if the
result was negative, would be of some importance.

During the conduct of these investigations, I have gratefully to
acknowledge the able assistance rendered by Mr. Robert Lennox, my
chief assistant. Valuable help has also been given by Mr. J. W.
Heath.

[J. D.]

* On the other hand, the exceptionally small refractivity value observed by
Lord Eayleigh in the case of helium shows that the critical pressure of this body
is proportionately high. It would therefore bo more difficult to liquefy than a
substance having about the same critical temperature, but possessing a lower
critical pressure, like hydrogen.

1896.] General Monthly Meeting. 147

GENEEAL MONTHLY MEETING,
Monday, April 13, 1896.

Sib James Ceiohton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Robert James Forrest, Esq.

Major-General Sir Francis Grenfell, G.C.M.G. K.C.B.

Marcus Warren Zambra, Esq.

were elected Members of the Eoyal Institution.

The Managers reported, That they had re-appointed Professor
James Dewar, M.A. LL.D. F.R.S. as Fullerian Professor of Chemistry.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

The Secretary of State in Council of India — Catalogue of the Library of the India
Office, Vol. I. Supplement. 8vo. 1895.
Annual Progress Report of the Archaeological Survey Circle for year ending
June, 1895. 8vo.
The Governor- General of India — Geological Survey of India : Records, Vol.

XXIX. Part 1. 8vo. 1896.
The British Museum (Natural History)— Ca,talogne of Birds, Vols. XXV. XXVII.
8vo. 1895-96.
Catalogue of Fossil Fishes, Part 3. 8vo. 1895.
Catalogue of Wealden Plants, Part 2. 8vo. 1893.
Guide to the British Mycetozoa. By A. Lister. 8vo. 1895.
Introduction to the Study of Rocks. By L. Fletcher. 8vo. 1896.
The Meteorological O^ce— Hourly Means for 1892. 4to. 1895.
Accademia dei Lincei, Beale, Roma — Atti, Serie Quinta : Rendiconti. Classe di
Scienze Morali, etc. Vol. IV. Fasc. 11, 12; Vol. V. Fasc. 1, 2. 8vo. 1896.
Classe di Scienze Fisiche, etc. Vol. V. Fasc. 4-6. 8vo. 1896.
Agricultural Society of England, Royal — Journal, Vol. VII. Part 1. 8vo. 1896.
Ahier, C. W. Esq. {the Author) — Unorthodox Economics. 8vo. 1896.
American Geographical Society — Bulletin, Vol. XXVII. No. 4. 8vo. 1895.
American Philosophical Society — The Theory of the State. By G. H. Smith. 8vo.

1895.
Armistead, J. J. Esq. (the Author) — An Angler's Paradise, and how to obtain it.

8vo. 1895.
Astronomical Society, Eoyal — Monthly Notices, Vol. LVI. No. 5. 8vo. 1896.
Bankers, Institute o/— Journal, Vol. XVII. Parts 2, 3. 8vo. 1896.
Beeby, W. H. Esq. — Pseudo-Nomenclature in Botany. 8vo. 1896.
Berlin, Koniglich Preussische Akademie der Wissenschaften — Sitzungsberichte,

1895, Nos. 39-53. 8vo.
Boston Public Library, U.S.A. — Bulletin for Jan. 1896. 8vo.

Handbook of the New Public Library in Boston. Compiled by H. vSmall. 8vo.
1895.
Botanic Society, Royal — Quarterly Record, No. 64. 8vo. 1895.
British Architects, Royal Institute o/— Journal, 1895-96, Nos. 9, 10.

L 2

148 General Monthly Meeting. [April 13,

British Astronomical Association — Journal, Vol. VI. No. 6. 8vo. 1896.
Brymner, Douglas, Esq. (the Archivist) — Report on Canadian Archives for 1895.

8vo. 1896.
Camera Club— Journal for March, 1896. 8vo.
Canada, Geological Survey of — Contributions to Canadian Palseontology, Vol. II.

Part 1. Svo. 1895.
Chemical Industry, Society o/— Journal, Vol. XV. Nos. 2, 3. Svo. 1896.
Chemical Society — Journal for March, 1896. 8vo.

Proceedings, Nos. 161, 162. 8vo. 1896.
Civil Engineers, Institution of — Minutes of Proceedings, Vol. CXXIII. Svo. 1896.
Danton, D. Esq. {the Author) — Lumiere, Poesie et Realite'. Svo. 1896.
Dublin, Royal /S'ocie^?/— Transactions, Vol. V. Parts 5-12; Vol. VI. Paxt 1. 4to.
1894-96.

Proceedings, Vol. VIII. Parts 3, 4. Svo. 1894-95.
Editors — American Journal of Science for March, 1896. Svo.

Analyst for March, 1896. Svo.

Anthony's Photographic Bulletin for March, 1896. 8vo»

Astrophysical Journal for March, 1896. Svo.

Athenajum for March, 1896. 4to.

Author for March, 1896.

Bimetallist for March, 1896.

Brewers' Journal for March, 1896. Svo.

Chemical News for March, 1896. 4to.

Chemist and Druggist for March, 1896. Svo.

Education for March, 1896. Svo.

Electrical Engineer for March, 1896. fol.

Electrical Engineering for March, 1896.

Electrical Review for March, 1896. Svo.

Electric Plant for March, 1896. Svo.

Engineer for March, 1896. fol.

Engineering for March, 1896. fol.

Homoeopathic Review for March, 1896.

Horological Journal for March, 1896. Svo.

Industries and Iron for March, 1896. fol.

Invention for March, 1896. Svo.

Law Journal for March. 1896. Svo.

Machinerv Market for March, 1896. Svo.

Nature for March, 1896. 4to.

Nuovo Cimento for Jan. 1896. Svo.

Physical Review for March-April, 1896. Svo.

Science Sittings for March, 1896. Svo.

Scientific African for March, 1896. Svo.

Scots Magazine for March, 1896. Svo.

Technical World for March, 1896. Svo.

Transport for March, 1896. fol.

Tropical Agriculturist for Feb. 1896. Svo.

Work for March, 1896. Svo.

Zoophilist for March, 1896. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXV. No. 120. 1896. Svo.
Essex County Technical Laboratories, Chelmsford — Journal for Feb.-March, 1896.

Svo.
Field Columbian Museum, Chicago — Handbook to Meteorite Collection. By O.
C. Farrington. Svo. 1895.

Authentic Letters of Columbus. By W. E. Curtis. Svo. 1895.

Flora of Yucatan. By C. F. Millspaugh. Svo. 1895.

Vertebral Column of Araia. By O. P. Hay. Svo. 1895.

Skeleton of Protostega gigas. By O. P. Hay. Svo. 1895.
Florence, Biblioteca Nazionale Centrale — Bolletino, Nos. 244, 246. Svo. 1896.
Franldin Institute— J ouixxaI for March, 1896. Svo.

1896.] General Monthly Meeting. 149

Geographical Society^ Royal — Geographical Journal for March, 1896. 8vo.

Glasgow PMlosophwal Society — Proceedings, Vol. XXVI. 1894-95.

Harvard College, U.S.A. — Annual Keports of the President and Treasurer 1894-95.

8vo. 18<>6.
Horticultural Society, Royal — Journal, Vol. XIX. Part 3. 8vo. 1896.
Imperial Institute — Imperial Institute Journal for March, 1896.
Japan, Imperial University — Journal of the College of Science, Vol. LX. Part 1.

8vo. 1895.
Johns Hophins University — University Studies: Fourteenth Series, No. 2. 8va.

1896.
American Chemical Journal, Vol. XVIII. No. 3. 8vo. 1896.
University Circular, Nos. 123, 124. 4to. 1896,
Linnean Society — Journal, No. 162. 8vo. 1896.
Liverpool, Literary and Philosophical Society of — Proceedings, Vols. XLIV.-XLIX.

1890-95.
London County Council Technical Education Board — London Technical Educa.-

tion Gazette for March, 1896. 8vo. 1895.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Fourth

Scries, Vol. X. No. 1. 8vo. 1896.
Menshrugge, G. Van der, Esq. (the Author)SvLr la pression hydrostatique negative.

8vo. 1893.
Sur la cause commune de la tension superficielle et de I'evaporation des liquides.

8vo. 1893.
Quelques pages de Thistoire d'un grain de poussiere. 8vo. 1894.
Sur la constitution de la couclie superficielle des corps solides. Svo. 1894.
Quelques exploits d'une particule d'air. 8vo. 1895.
Meteorological Society, Royal — List of Fellows, 1896. 8vo.

Quarterly Journal, No. 97. 8vo. 1896.
Metropolitan Asylums Board — Report on the use of Antitoxic Serum in the Treat-
ment of Diphtheria in the Hospitals of the Board during 1805. Svo. 1896.
Microscopical Society, Royal — Journal, 1896, Part 1. Svo.

Mitchell, Messrs. & Co. (the Publishers) — Newspaper Press Directory for 1896. Svo.
Munich, Bavarian Academy of Sciences, Royal — Sitzungsberichte, 1895, Heft 3.

1896.
New Zealand, Registrar-General for — Statistics of the Colony of New Zealand for

1894. Svo. 1895.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLIV. Part 5; Vol. XLV. Parts 1, 2. Svo. 1895-96.
Eeport of Proceedings of the Flameless Explosives Committee, Part 3. Svo

1896.
Odontoloqical Society of Cheat Britain — Transactions, Vol. XXVIII. No. 4. Svo

1896.
Onnes, Professor H. KamerUngh — Communication from the Laboratory of

Physics at the University of Leiden, Nos. 1, 3, 20, 21, 23. Svo. 1895.
Paris, Societe Fran';aise de Physique — Seances, 1895, Fasc. 3°. Svo. 1896.

Bulletin Bimensuel, 1896 et seq. Svo.
Pharmaceutical Society of Great Britain — Journal for IMarch, 1896. Svo.
Photographic Society, Royal—The Photographic Joiu-nal, Dec.-Feb. 1895-96. Svo.
Physical Society of London — Proceeding:^, Vol. XIV. Part 3. Svo. 1896.
Prince, C. L. Esq. F.R.A.S. F.R.Met.Soc. — The Summary of a Meteorological

Journal. Svo. 1895.
Richards, Admiral Sir G. H. K.CB. J'.E./S^.— Report on the present state of the

Navigation of the River Mersey (1895). Svu. 1896.
Rio de Janeiro Ohservatory — Me'thode Graphique pour la dete'rioination des heures

approchees des eclipses du soleil et des occultatious, par M. Cruls. Svo.

1894.
Le Climat de Rio de Janeiro, par M. Cruls. Svo. 1892.
Dettjrininacao das Pooicocs geographiques do liodeis, Entre Rios, etc. par M.

Cruls. Svo. 1894.

150 General Monthly Meeting, [April 13,

J^ome, Ministry of Public WorTcs—Giomale del Genio Civile, 1895. Fasc. 12^

And Designi. fol.
Eoyal Engineers, Corps o/— Professional Papers, Vol. XXI. 1895. 8vo.

Foreign Translation Series, Vol. I. Nos. 1, 2. Svo. 1895-96.
Eoyal Society of London — Philosophical Transactions, Vol. CLXXXVII. A,
Part 2, Nos. 171-3 ; B, Part 2, No. 133. 4to. 1896.
Proceedings, No. 355. Svo. 1895-96.
Saint Bartholomew's Hospital — Keports, Vol. XXXI. Svo. 1895.
Saxon Society of Sciences, Royal —
Mathematisch-Physische Classe —
Berichte, 1895, Nos. 5, 6. Svo. 1896.
Abhandlungen, Band XXIII. No. 1. Svo. 1896.
Selborne Society— 'Nature Notes for March, 1896. Svo.
SeU, Henry, Esq. (the Compiler)— SelV 3 Dictionary of the World's Press, 1896.

Svo.
Society of Arts — Journal for March, 1896. Svo.
Statistical Society, Boy al— J ouxnol, Vol. LIX. Part 1. Svo. 1896.
Tacchini, Prof. P. Hon. Mem. B.I. {the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXV. Uisp. 1% 1\ 4to. 1896.
United Service Institution, Royal — Journal, No. 217. Svo, 1896.
United States Department of Agriculture— KonihlY Weather Keview for August-
Sept. 1895. 4to.
Experiment Station Record, Vol. VI. Nos. 8-11.
Climate and Health, Nos. 5, 6. 4to. 1895.

The Jack Rabbits of the United States. By T. S. Palmer. Svo. 1896.
United States Patent 0#ce— Official Gazette, Vol. LXXIII. Nos. 10-14 ; Vol.
LXXIV. No. 1. Svo. 1895-96.
Alphabetical Lists of Patentees and Inventions for 1895, Part 2. Svo. 1895.
Unwin, T. Fisher, Esq. (the Publisher) — Cosmopolis for February, 1896. Svo.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1896:

Heft 2. 4to.
Vienna, Geological Institute, iio?/aZ— Verhandlungen, 1895, Nos. 14-18. Svo.
Wisconsin Academy of Sciences, Arts and Letters — Transactions, Vols. IV. VI.

VIII. IX. Parts 1, 2, X. Svo. 1878-95.
Zurich, Naturforschende Gesellschaft — Vierteljahrsschrift, Jahrgang XV. Hefte
3, 4. Svo. 1895.
Neujahrsblatt, No. 98. Svo. 189«.

1896.] Professor Lippnann on Colour Photography. 151

WEEKLY EVENING MEETING,
Friday, April 17, 1896.

Sir James Ckichton-Browne, M.D. LL.D. F.R.S. Treasurer and
V ice-President, in the Cliair.

Professor G. Lippmann, Membre de I'lnstitut (France).
Colour Photography,

The problem of colour photography is as old as photography itself.
The desire of fixing the colours as well as the design of the beautiful
image thrown on the screen of the camera, very naturally occurred to
the earliest observers. Since the beginning of this century three
distinct solutions of the problem have been realised.

The first solution, not quite a complete one, is founded on the
peculiar properties of a silver compound, the violet subchloride of
silver. E. Becquerel (1860) converted the surface of a daguerreotype
plate into this silver compound, and by projecting on it the image of
the solar spectrum, and other objects, obtained good coloured impres-
sions. Poitevin substituted paper for the silver plate as a substratum.
No other substance has been discovered that can play the part of the
subcbloride of silver. Moreover the image is not fixed, in the photo-
graphic sense of the word ; that is, the coloured impression is retained
for any length of time in the dark, but it is blotted out by the action
of daylight. The reason of it is this : the Becquerel images are
formed by coloured silver compounds, which remain sensible to light ;
so that they are destroyed by the continued action of light, in virtue
of the same action which gave them birth. Despite the numerous
experiments made by Becquerel, Poitevin, Zenker and others, no
substance has been found that is capable of destroying the sensibility
of the subchloride for light without at the same time destroying its
colour.

The second method for colour photography is an indirect one,
and may be called the three-colour method. It was invented in
France by Ch. Cros, and at the same time by M. Duces du Hauron
(1869). German authorities claim the priority of the idea for Baron
Bonstetten. Three separate negatives (colourless) are taken of an
object through three coloured screens. From these three positives
(equally colourless) are made ; and, lastly, the colour is supplied to
these positives by means of aniline dyes or coloured inks. Thus
three coloured monochromatic positives are obtained, which by super-
position give a coloured image of the model. In the ingenious
process lately invented by Prof, Joly, the three negatives, and appa-

152 Professor G. Lippmann [April 17,

rently the corresponding three positives, are obtained interwoven on
one and the same plate. The three-coloured method can give a very-
good approximation to the truth, and has probably a great future
before it. We may call it, nevertheless, an indirect method, since the
colours are not generated by the action of light, but are later supplied
by the application of aniline dyes or other pigments. Moreover, the
choice of these pigments, as well as of the coloured screens through
which the negatives have been obtained, is in some degree an arbitrary
choice.

The third and latest method by which colour photography has
been realised is the interferential method, which I published in 1891,
and the results of which I beg to lay before you this evening. It
gives fixed images, the colours of which are due to the direct action of
the luminous rays.

For obtaining coloured photographs by this method, only two
conditions are to be fulfilled. We want (1) a transparent grainless
photographic film of any kind, capable of giviug a colourless fixed
image by the usual means ; and (2) we want a metallic mirror, placed
in immediate contact with the film during the time of exposition.

A mirror is easily formed by means of mercury. The photo-
graphic plate being first enclosed in a camera slide, a quantity of
mercury is allowed to flow in behind the plate from this small
reservoir, which is connected with the slide by a piece of india-rubber
tubing.* The slide is then adapted to the camera, and the action
of light allowed to take place. After exposure the slide is sepa-
rated from the camera, the mercury reservoir lowered so as to
allow the mercury to flow back into it; the photographic plate is
then taken out, developed and fixed. When dry, and examined by
reflected light, it appears brilliantly coloured.

The sensitive film may be made either of chloride, iodide or
bromide of silver, contained in a substratum either of albumen, col-
lodion or gelatine. The corresponding developers, either acid or
alkaline, have to be applied ; the fixation may be cyanide or bromide
of potassium. All these processes I have tried with success. For
instance, the photograph of the electric spectrum now projected before
your eyes, has been made on a layer of gelatiuo-bromide of silver,
developed with amidol, and fixed with cyanide of potassium.

As you see, bright colour photographs may be obtained without
changing the technique of ordinary photography: the same films,
developers and fixators have to be employed ; even the secondary
operations of intensification and of isochromatisation are made use
of with full success. The presence of the mirror behind the film
during exposure makes the whole difference. From a chemical point
of view nothing is changed, the result being a deposit of reduced
silver left in the film, a brownish, colourless deposit. And yet the

* The g;lass of the photographic plate has to be turned towards the objec-
tive, the film in contact with the metallic mirror.

1896.] on Colour Photographif, 153

presence of a mirror during exposure causes the colourless deposit to
show bright colours. Of course we want to know how this is done ;
we require to understand the theory of those colours.

We all know that colourless soap- water gives brilliant soap-bubbles ;
the iridescence of mother-o'-pearl takes birth in colourless carbonate
of lime ; the gorgeous hues of tropical birds are simply reflected
from the brownish substance which forms the feathers. Newton
discovered the theory of these phenomena, and subjected them to
measurement ; he invented for the purpose the experiment called by
the name of Newton's rings. Newton showed, as you know, that
when two parallel reflecting surfaces are separated by a very short
interval, and illumined by white light, they reflect only one of the
coloured rays which are the constituents of white light. If, for
instance, the interval between the reflecting surfaces is only t-qIq o of
a millimetre, violet rays are alone reflected, the rest being destroyed by
interference : that is, the two surfaces send back two reflected rays
whose vibrations interfere with one another, so as to destroy every
vibration except that which constitutes violet light. If the interval
between the reflecting surfaces be augmented to toIo^ millimetre,
the destruction of vibration takes places for every vibration except that
of red light, which alone remains visible in this case.

If we consider now this photograph of the spectrum, and especially
the violet end of the image, we find that this is formed by a deposit
of brown reduced silver. In the case of an ordinary photograph,
this deposit would simply be a formless cloud of metallic particles ;
here the cloud has a definite, stratified form; it is divided into a
number of thin, equidistant strata, parallel to the surface of the plate,
and To§o 0- uiiHinietre apart These act as the reflecting surfaces
considered by Newton, and as they are at the proper distances for
reflecting violet rays, and these alone, they do reflect violet rays.

The red extremity of the photograph is equally built up of strata
which act in a like manner ; only their distance intervals here amount
to tfSoo niillinietre, and that in the proper interval for reflecting
red light. The intermediate parts of the spectral image are built up
with intermediate values of the interval, and reflect the intermediate
parts of the spectrum.

The appearance of colour is therefore due to the regular structure
above described, imprinted on the photographic deposit. The next
question is — How has this very fine, peculiar and adequate structure
been produced ?

It is well known that a ray of light may be considered as a
regular train of waves propagated through the ether, in the same
way as waves on the surface of water. The distance between two
following waves is constant, and termed the wave-length ; each sort
of radiation, each colour of the spectrum, being characterised by a
particular value of the wave-length. Now when a ray of light falls on
a sensitive film, this train of waves simply rushes through the film
with a velocity of about 300,000 kilometres per second ; it impresses

154 Professor G. Lippmann [April 17,

the film more or less strongly, but leaves no record of its wave-length,
of its particular nature or colour, every trace of its passage being swept
out of form by reason of its swift displacement. The impression
therefore remains both uniform and colourless. Things change,
however, as soon as we pour in mercury behind the plates, or other-
wise provide for a mirror being in contact with it. The presence of
the mirror changes the propagated waves into standing waves. The re-
flected ray is, namely, thrown back on the incident ray, and interferes
with its motion, both rays having equal and opposite velocities of
propagation. The result is a set of standing waves — that is, of waves
surging up and down, each in a fixed plane. Each wave impresses the
sensitive film where it stands, thus producing one of these photo-
graphic strata above alluded to. The impression is latent, but comes
out by photographic development. Of course the distance between
two successive strata is the distance between two neighbouring waves ;
this, theory shows, is exactly half the wave length of the impressing
light. In the case of violet, for instance, the wave-length being
^o^oQ millimetres, half the wave-length in the above-quoted distance
of ToJoo^ millimetres ; this, therefore, is at the same time the interval
between two standing waves, in the case of violet light the interval
between two successive photographic strata, and at last it is the interval
required to exist, according to Newton's theory, for the said strata
reflecting voilet rays, and making these alone apparent when illumi-
nated by white light.

The colours reflected by the film have the same nature and origin
as those reflected by soap-bubbles or Newton's rings ; they owe their
intensity to the great number of reflecting strata. Suppose, for
instance, the photographic film to have the thickness of a sheet of
paper (one-tenth of a millimetre), the fabric built in it by and for
a violet ray is five hundred stories high, the total height making
np one-tenth of a millimetre. Lord Eayleigh, in 1887, has proved
a priori that such a system is specially adapted to reflect the corre-
sponding waves of light.

How are we now to prove that the above theory is really applicable
to the colour photograph you have seen ? How can we demonstrate
that those bright colours are due not to pigments, but to the inter-
ference, as in the case of soap-bubbles ? We have several ways of
proving it.

First of all, we are not bound to the use of a peculiar chemical
substance, such as Becquerel's subchloride of silver ; we obtain colour
with a variety of chemicals. We can, for instance, dispense entirely
with the use of a silver salt; a film of gelatine or coagulated
albumen impregnated with bichromate of potash, then washed with
pure water after exposure, gives a very brilliant image of the spectrum.

Secondly, the colours on the plate are visible only in the direction
of specular reflection. The position of the source by which we
illumine the photograph being given, we have to put the eye in a
corresponding position, so as to catch the regularly reflected rays. In

1896.] on Colour FJiotograjphy. 155

«very other position we see nothing but a colourless negative. Now,
as you are aware, the colours of pigments are seen in any direction.
By projecting again a photograph of the spectrum, and turning it to
and fro, I can show you that the colours are visible only in one
direction.

Thirdly, if we change the incidence of the illuminating rays, that
is, if we look at the plate first in a normal direction, then more and
more slantingly, we find that the colours change with the incidence
exactly as they do in the case of soap bubbles, or of Newton's rings ;
they change according to the same law and for the same reasons.
The red end of the spectrum turns successively to orange, yellow,
green, blue and violet. The whole system of colours, the image of
the spectrum, is seen to move down into the part impressed by the
infra-red. This is what we expect to happen with interference
colours, and what again we cannot obtain with pigments.

Fourthly, if while looking at the film normally, we sufier it to
absorb moisture — this can be done by breathing repeatedly on its
surface — we see that the colours again change, but in an order oppo-
site to that above described. Here the blue end of the spectrum is
seen to turn gradually green, yellow, orange, red, and finally infra-
red, that is, invisible. The spectrum this time seems to move up into
the ultra-violet part of the improved film. By suffering the water to
evaporate, the whole image moves back into its proper place ; this
experiment may be repeated any number of times.

The same phenomenon may be obtained with Newton's apparatus,
by slowly lifting the lens out of contact with the plane surface. The
explanation is the same in both cases. The gelatine swells up when
imbibing moisture. If we consider, for instance, the violet of the
spectrum, the small intervals between the strata corresponding to
violet rays, gradually swell up to the values proper for green, and for
red, and for infra-red ; green, then red, then infra-red are therefore
successively reflected.

We will wet this photograph of the spectrum with^water, project
it on the screen, and watch the colours coming back in the order pre-
scribed by theory.

It is necessary to use a transparent film, since an opaque one,
such as is commonly in use, would hide the mirror from view ; the
sensitive substance must be grainless, or at least the grains must be
much finer than the dimensions of the strata they are intended to
form, and therefore wholly invisible. The preparation of transparent
layers gave me at first much trouble ; I despaired for years to find a
proper method for making them. The method, however, is simply
thus : if the sensitive substance (the silver bromide, for instance) be
formed in presence of a sufficient quantity of organic matter, such as
albumen, gelatine or collodion, it does not appear as a precipitate ; it
remains invisible ; it is formed, but seems to remain dissolved in the
organic substratum. If, for instance, we prepare a film of albumeno-
iodide in the usual way, only taking care to lessen the proportions of

156 Colour Fhotography. [April 17,

iodide to half per cent, of the albumen, we get a perfectly transparent
plate, adapted to colour photography.

We want now to go a step further. It is very well for physicists
to be contented with working on the spectrum, since that contains
the elements of every compound colour ; but we all desire to be able
to photograph other objects than the spectrum — common objects with
the most compound colours. We have again but to take theory as a
guide, and that tells us that the same process is able to give us either
simple or compound colours. We have then to take a transparent
and correctly isochromatised film, expose it with its mercury backing,
then develop and fix it in the usual way; the plate, after drying,
gives a correct coloured image of the objects placed before the camera.
Only one exposure, only one operation is necessary for getting an
image with every colour complete.

A plausible objection was offered at first to the possibility of
photographing a mixture of simple coloui-s. The objection was this :
a ray of violet gives rise to a set of strata separated by a given
interval ; red light produces another set of strata with another
interval ; if both co-exist, the strata formed by the red are sure to
block out here and there the intervals left between the strata formed
by the violet. Is it not to be feared that one fabric will be blurred
out by the other, and the whole effect marred ? The confusion would
be still worse if we consider the action of white light, which contains
an infinity of simple components ; every interval here is sure to be
blocked up.

Mathematical analysis, however, shows this objection to be
unfounded ; we have great complexity, but not confusion. Every
compound ray, both coloured and white, is faithfully rendered. As
an experimental proof of this, we will project on the screen photographs
of very different objects, namely, stained glass windows, landscapes
from nature, a portrait made from life, and vases and flowers.

That the colours here observed are due to interference, and not to
the 23resence of pigments, can be shown in the same way as with the
spectrum. Here, again, we observe that the colours are visible only in
the direction of sj^ecular reflection, that they change with the angle
of incidence, that they change and disaj)pear by wetting, and reapj)ear
by drying. Pigments remain equally visible and unaltered in colour
under every incidence. If we attempted to touch up one of our
photographs with oil or water-colours, the adulterated place would
stand out on a colourless background by merely observing by diffused
light. It is therefore impossible either to imitate or touch up a colour
photograph made by the above-described interferential method.

[G. L.]

1896.] The Circulation of Organic Matter. 157

WEEKLY EVENING MEETING,

Friday, April 24, 1896,

Basil Wood Smith, Esq. F.E.A.S. F.S,A. Vice-President,
in the Chair.

Professor G. V. Poore, M.D. F.R,C.P.

The Circulation of Organic Matter.

It is quite impossible to define " organic matter," or to indicate the
line, if there be any, between organic and inorganic.

Organic matter is the material of which living things are made.
When a chemist analyses anything which is the product of life,
whether vegetable or animal, he often speaks of his incombustible
residue or ash as " inorganic matter," but this is clearly an arbitrary
use of the term, for this incombustible residue has formed an indis-
pensable part of one living thing, and may in due time be incorporated
with other living things as something which they cannot do without.

It may well be that everything of which we have knowledge
(even including the igneous rocks) has at one time or another formed
part of a living organism, and it is certain that a large proportion of
the commoner chemical elements may form a part, more or less
indispensable, of the bodies and framework of plants or animals.

Oxygen, hydrogen, nitrogen, carbon, chlorine, sulphur, phosphorus,
iron, sodium, potassium and calcium seem to be indispensable to
almost every living thing. Many more of the elements are constantly
found in some organisms, while others, such as lead, mercury, silver,
&c., may be temporarily incorporated with living bodies.

We shall deal to-night mainly with those elements which are
pre-eminently mobile, which are constantly changing and exchanging,
combining and separating, and which are readily combustible. For
practical purposes one might indeed use the terms " organic " and
" combustible " to signify the same thing.

With regard to solid matter, the power of readily circulating
implies a readiness of combustibility, but it must be remembered
that there is no hard line between combustible and incombustible.
This is a matter of temperature, and many things which are incom-
bustible here are said to be blazing in the sun.

The combustion of organic matter may take place slowly or with
moderate rapidity, or with explosive violence.

When we burn coal, which is a vegetable product, we find that
the carbon and hydrogen escape as carbonic acid and water, accom-

158 Professor G. V. Poore [April 24^

panied by nitrogen, sulphuric acid and volatile hydrocarbons. The
residue consists mainly of silica and alumina, which are removed from
the furnace in the form of clinker and ash. The water ultimately
returns to the earth in the form of rain or dew, the carbonic acid is
ultimately absorbed by green plants, and, by stimulating the growth
of these, helps to furnish us with more combustible material, while
the residue is almost a waste product. Thus, in this example we find
that the carbon and watery vapour readily " cireulate,^^ while the
residue can only do so after a long interval of time, and is practically
lost. The volatile hydrocarbons and sulphuric acid, being poisonous
to herbage, are a source of practical loss rather than gain.

Let us take next the case of an animal, which is really a living^
furnace, browsing in a field ; as it browses we may often see the
breath, which is the smoke of this furnace laden with carbonic acid
and water, escaping from its mouth and nostrils, and it is probable
that the green leaves of the herbage absorb this carbonic acid almost
as soon as it escapes, and, appropriating the carbon, return oxygen to
the animal to help its respiration and combustion. The animal as it
eats continues to grow and increase in bulk and value, whereas the
artificial furnace in which the coal is burnt tends steadily to wear
out and decrease in value. As it browses and grows, the droppings of
the animal nourish the herbage which here and there, by patches of
more vigorous growth and deeper green, aflbrd sure evidence of the
value of these waste products.

In this arrangement there is no waste, for both the animal and
the herbage, by a process of mutual exchange and the circulation of
organic matter, increase in value.

Not only is there no waste, but, strange as it may seem, there is a
positive gain, with no loss whatever. The furnace and the fuel are
both increased ! This increase can only be apparent, and not real,
for it is well known that although we may alter the form of matter,
we can add nothing to and subtract nothing from the sum total of
the world.

One would say that this apparent increase is due to the stimulat-
ing effect of the excreta upon the soil, which enables us to draw
something extra from that inexhaustible storehouse of plant-food and
water, and enables the animal to use these materials, instead of allow-
ing them to drain to the springs, and so find their way to the sea.
We know that a far greater proportion of the rainfall percolates
through barren soil than through soil bearing crops. If this be so,
there is a practical increase of the land at the expense of the water.

Again, we must remember that our knowledge of the sources of
the gases of the atmosphere is not complete. It may be that all the
oxygen of the air is furnished by the green leaves of plants, and all
the carbonic acid by processes of respiration and combustion, but we
are by no means sure of this. Of the sources of the atmospheric
nitrogen we know nothing. Now it is certain that much of the carbon
of the atmosphere is appropriated by the plants, and much of the

1896.] on the Circulation of Organic Matter, 159

oxygen by the animal. If among the herbage there be plants of
clover, it is now certain that much of the atmospheric nitrogen will
be drawn into the soil to nourish these plants and generally to increase
its fertility. Whether the return of oxygen, carbon and nitrogen is,
in the long run, equal to the intake we cannot tell.

When, however, we ponder upon the gradual increase of vegetable
soil or humus with which the bare rocks have been clothed in the
course of ages, it is almost impossible not to come to the conclusion
that the humus and with it the fertility of the soil has steadily in-
creased at the expense of the sea on the one hand, and, possibly,
of the atmosphere on the other. To put the matter in the form of
question and in other terms, " Does the Lithosphere increase at the
expense of the Atmosphere and the Hydrosphere ? " Does the land
increase at the expense of sea and air ? Be this as it may, it seems
certain that by scrupulous return to the soil of all that comes out of
it the resources of nature are made increasingly available for tho
benefit of man.

When organic matter is mixed with water, a process of putrefac-
tion and fermentation is started, and the organic matter, instead of
undergoing oxidation, is reduced, and among the commoner products
■of this process are ammonia with sulphuretted hydrogen and marsh-
gas, which are both combustible. These processes furnish us with
other combustible matters among the commonest of which are the
alcohols, the familiar products of fermentation.

It is interesting to note the tendency of organic matter, when
mixed with water, to give rise to explosive and combustible products.
Explosions in cesspools and sewers have occurred many times.
When wet hay is stored in stack it catches fire. When we stir the
mud at the bottom of a pond or river, bubbles of combustible marsh=
gas rise to the surface. The coal measures are due to the storing
under water of semi-aquatic plants which have been preserved by
being silted up, and we know that coal is full of defiant gas, marsh-
gas, sulphuretted hydrogen and carbon monoxide, which are all com-
bustible, and that the carbonaceous residue, charged with volatile
and combustible hydro-carbons, forms the chief fuel of the civilised
world. Peat is formed in ways analogous to that of coal, and the
so called mineral oils are certainly the products of organic matter
which has been silted up.

These subterranean stores of combustibles, all of organic origin,
are, as we know, prodigious in quantity. Nobody can predict the time
which it will take to exhaust the coal measures of the world, and we
know for a fact that the sacred fires of Baku on the Caspian, fed by
subterranean reservoirs of naphtha, have been burning for centuries.

When we see the end of a tin of " preserved meat " bulged, we
know that the gas-forming organisms have been at work within, and
when the bed of the lower reaches of the Mississippi rises as a small
mud mountain, spluttering with carburetted hydrogen, we know

160 ProfessoT G. F. Poore [April 24,

that analogous forces have been in operation. It seemsj indeed, to
be a law of nature that the ultimate destiny of organic matter is to
" circulate," and that if it do not do so quietly, as in the ordinary pro-
cesses of nutrition in plants and animals, it merely bides its time
and ultimately attains its end with more or less destructive violence.

Nitre (nitrate of potash or nitrate of soda) is an organic product,
and sulphur is an essential constituent of all or nearly all organisms.
Of the three ingredients of gunpowder, two (charcoal and saltpetre)
are, it is certain, of exclusively organic origin, and the third, sulphur,
may be so also.

All the common combustibles with which we are familiar are
certainly of organic origin, and one is almost forced to the conclusion
that in this world life must have preceded combustion. If we are to
explain what Jiaa been by what is, such a conclusion is irresistible.
Are we quite sure that volcanoes, which are seldom far from the sea,
are not fed by old deposits of organic matter which has collected in
the primeval ocean, and like the more recent coal measures, have
been silted up,

Wliat has been the destiny of the protoplasm of the countless
animals and plants which are found in geologic strata? What part
have ancient microbes had in the formation and disruption of the
successive layers of which this earth is formed ? These are questions
which force themselves upon the mind, but which I will not now
attempt to answer. This biological view of the cosmogony which
subjects the world equally with all that is upon it to the laws of
development, evolution and decay, does not, I believe, present so
many difficulties as might at first sight appear.

" Omne vivum ex vivo " is a law of nature, and all organic bodies
spring from organic antecedents. Organic matter is our capital in
this world, and the more frequently we can turn it over, and the
more quickly and efiiciently we can make it circulate, the more
frequent will be our dividends. If we burn organic matter, we may
get a good dividend of energy, but nothing further is to be expected.
The construction of the furnace involves an outlay of capital which
steadily diminishes as the furnace wears out by frequent use. If we
burn organic matter merely to be rid of it, we spend our money for
the sole purj)ose of dissipating our capital. The function of fire is
to destroy and sterilise.

If we mix organic matter with large quantities of water, we have
to encounter all the evils and annoyance of putrefaction, and if, when
so mixed, we send it to the sea, we have no material gain of any kind.
We spend our money for the purpose of dissipating our capital.

We may place the water containing the organic matter upon the
land, and in tropical countries this is done with excellent effect for the
production of rice, a semi-aquatic plant which, according to Professor
Georgeson, Professor of Agriculture in the Imperial University of
Tokio, is said to prefer its nitrogen in the form of ammonia. The

1896.] on the Circulation of Organic Matter. 161

same authority states that nitrification does not take place under
water, and careful experiments carried out at Tokio show that sulphate
of ammonia is a much better manure for irrigated rice than nitrate of
soda.

In our damp climate sewage farming has proved a dismal failure,
and the difficulties seem to increase with the quantity of water which
has to be dealt with. Excess of water drowns the humus, and nitri-
fication cannot go on in a soil the pores of which are closed by excess
of moisture.

The living earth, teeming with aerobic microbes, must be allowed
to breathe. It needs for this purpose a certain amount (about 30 per
cent.) of moisture, but it stands drowning no better than a man does,
and if it be drowned, agricultural failure is inevitable.

If we carefully return to the upper layers of the humus, in which
air and microbes exist in plenty, the residue of everything which we
extract from it, we inevitably increase the thickness of the humus and
its fertility. Our capital increases, and our dividends increase and
recur with a frequency which depends upon the climate.

With tlirifty and high cultivation it may, indeed, prove profitable
to compensate defects of climate by the use of glass and artificial
heat.

The part played in the economy of nature by fungi and bacteria—
the new learning of the last half-century — is an addition to human
knowledge which is destined to revolutionise our views of many
natural phenomena. It has already exercised enormous propulsive
power on human thought, and has stimulated our imaginations scarcely
less than when, to use the words of Froude, " the firm earth itself,
unfixed from its foundations, was seen to be but a small atom in the
awful vastness of the universe."

This knowledge has provided us with a new world peopled with
organisms in numbers which, like the distances of the astronomers
and the periods of the geologists, are really unthinkable by the
human mind. Their variety also, both in form and function, is, for
practical purposes, infinite.

When, with the help of the many inventions of the optician and
the dyer, we catch a glimpse of things which a few years back were
"undreamt of in our philosophy," and when we reflect that these
organisms are certainly the offspring of " necessity," and are probably
mere indications of infinities beyond, we cannot be too thankful for
the flood of light which these discoveries have shed upon the enormity
of human ignorance.

The lower animals and the lower vegetable organisms (fungi and
bacteria) co-operate in a remarkable way in the circulation of organic
matter.

In the autumn the gardener, with a view to what is called '* leaf
mould," sweeps the dead leaves into a heap where they are exposed
to air and rain. This heap when thus treated gets hot, and last

Vol. XV, (No. 90.) m

162 Professor G. V. Poore [April 24,

autumn I found that the temperature of such a heap had risen in the
course of a week or so to 104° F., and remained at a temperature
considerably above that of the surrounding air during the whole
winter. On turning it over after a month or so one found in it a
large number of earth worms and endless fungoid growths visible to
the naked eye, and one felt sure that it was swarming with countless
millions of bacteria, invisible except to the highest powers of the
microscope. In the beginning of March this heap, much reduced in
size, was spread loosely over a patch of ground which was previously
dug. If one examined that ground to-day one would scarcely recog-
nise the structure of leaves, and in a few weeks more it will have
become nothing but ordinary garden mould, and anything planted in
it will grow with vigour. This is a familiar every-day fact.

We know also that noisome filth spread over a field by the farmer
in the autumn or winter loses its ofiensiveness in a few days, and by
the spring neither our eyes or noses give us any clue to the cause of
the fertility of the field which is covered with ordinary "mould."
This process of " humification " is largely due to earth worms
and other earth dwellers, which pass the earth repeatedly through
their bodies, and in doing so reduce it to a very fine powder. I have
upon the table some worm castings picked off a lawn, and which,
after being slowly dried, have been gently sifted through muslin.
Those who have never examined a w^orm casting in this way will be
interested to see of what an imjmlpable dust the greater part is com-
posed, and will also note the considerable size of the pieces of flint
and grit which the animal has used in its living mill, and which have
been separated by the muslin sieve.

These castings are full of microbes, and those who will take the
trouble to scatter the smallest conceivable j^inch of this impalpal)le
dust upon a sterilised potato, after the manner and with all the pre-
cautions familiar to bacteriologists, will obtain an abundant and varied
growth of bacteria and moulds, which will completely baffle their
powers of enumeration and discrimination.

The greatest hindrance in the bacterial examination of the soil is
this p.nibarras de richesses, which makes the isolation of difierent
species a matter of extreme difficulty.

The bacteria exist in the soil in countless millions, but it must
be remembered that they get fewer as we go deeper. The first few
inches of the soil are, in the matter of bacterial richness, worth all
the rest, and at a depth of five or six feet they apj^ear to be almost
non-existent. The practical lesson which we have to lay to heart in
applying this knowledge is that the upper layers of the soil are the
potent layers in bringing about the circulation of organic matters,
and that if we wish to hasten this process we must be careful to place
our organic refuse near the surface and not to bury it deeply, a pro-
cess by which the circulation is inevitably delayed or practically
prevented. If we bury it deeply we not only get no good, but we
may get harm by poisoning our wells and springs.

1896.] on the Circulation of Organic Matter, 163

It is the samo with organic liquids. If these be poured on the
surface, the " living earth " (i. e. the humus stuffed with animal and
microbial life) purges them of their organic matter, and transmits a
relatively pure liquid to the deeper layers. If they be taken to the
barren subsoil direct, as in underground sewers and cesspools, they
escape the purifying action of air and aerobic organisms, and inevitably
poison the water. Filthy liquids accumulating in cesspools and
leaking under pressure to our wells have cost us health and money
incalculable.

Liquids poured upon the surface cannot, owing to the crumby
nature of the humus, exert any appreciable hydraulic pressure. This
is a fact of huge importance in the practical management of organic
refuse.

All effete organic matter instantly becomes the prey of animals
and plants. The dead body of an animal teems with life — " Le roi
est mort, vive le roi." M. Megnin, a skilled entomologist and a
member of the French Academy of Medicine, has made a study,
which is full of gruesome interest, of the living machinery which
makes away with the bodies of animals not buried but exposed to the
air and protected from beasts of prey.

M. Megnin shows that the destruction of the animal is accom-
plished in no haphazard fashion, but that successive squadrons of
insects are attracted by the successive stages of putrefaction.

The first squadron which arrives, sometimes before death and
always before putrefaction, consists entirely of dipterous insects,
house-flies and their relative the blow-fly.

The next squadron are also diptera, and are said to be attracted
by the commencing odour of decomposition. These squadrons use
the carcase as a procreant cradle, and thus ensure the nourishment of
the larvae so soon as they are hatched. Amongst these flesh-seeking
flies there are said to be specialists which prefer the flesh of particular
animals.

The third squadron is attracted when the fat begins to undergo
an acid fermentation. These consist of coleoptera and lepidopter.%
beetles and butterflies, and among them is Dermestes Lardarius, the
Bacon Beetle.

^hen the fats become cheesy, the diptera reappear, and among
them is Pyopliila Casei, the fly which breeds jumpers in cheese, who is
accompanied by a beetle the larvae of which are connoisseurs of
rancidity.

When the carcase becomes ammoniacal, black and slimy, it is
visited by a fifth squadron of flies and beetles.

And these are succeeded by the sixth squadron, consisting of acari
or mites, whose function it is to dry up the moisture and reduce the
carcase to a mummy-like condition.

The dried carcase proves attractive to the seventh squadron, con-
sisting of beetles and moths, some of which are the familiar pests of

M 2

164 Professor G. V. Poore [April 24,

tlie housewife, the furrier, and the keepers of museums. These
animals gnaw the softer parts, such as ligaments, and leave nothing
but a jfine powder behind them, which is in fact their dung.

The last and eighth squadron consists solely of beetles, which
clean up the debris, in the shape of dung, shells, pupa cases, &c., of
the seven squadrons which have preceded them.

M. Megnin, being an entomologist and not a bacteriologist, deals
exclusively with the insects concerned in making away with a carcase,
but it is evident that bacteria work hand in hand with them.

There are many other instances which may be quoted of the co-
operation of fungi with other organisms, and it is only of late years
that we have appreciated the fact of symbiosis or the living together
of two organisms for the mutual benefit of each. This fact was first
pointed out in so-called lichens, which are now shown to be comjjles
bodies consisting of a fungus and an alga, living in symbiotic com-
munity for the mutual benefit of each.

It was next shown that the Papilionaceous Leguminos^ are imable
to flourish without certain bacterial nodules which grow uj)on their
roots, and by the instrumentality of which they can appropriate the
nitrogen of the air, and thus the fact, familiar for centuries, that
the leguminosae leave the ground in a state of great fertility, while
they are singularly independent of nitrogenous manures, has been
explained.

But if the plants themselves are independent of dung, it is not so,
apparently, with the symbiotic nodules, which seem to flourish far
more vigorously in rich garden ground than they do in comparatively
poor farm land. Thus Sir John Lawes has grown clover in a rich
old garden for forty-two years, and has had luxuriant crops every
year.

According to my own observation on the scarlet runner bean these
nodules are more plentiful upon the roots which grow superficially
than upon those which run deeply.

Symbiosis is observable in many plants other than leguminos88,
and it is certain that many of our big forest trees depend for their
nourishment upon fungi which grow upon their roots.

By the kindness of my colleague. Professor F. \V. Oliver, I am
able to show you upon the screen the so-called Mycorhiza as it grows
upon the rootlets of the beech.

In the upper left-hand corner is a portion of root showing its
characteristic fungoid covering (natural size). To the right is a por-
tion enlarged — the thinner strands behind, being parts of the fungus
in the soil without an axis of root. Below is a root apex with fungal
sheath enlarged.

The next slide is from a drawing, by Professor Oliver, of Sarcodes
Sanguinea, the Californian snow plant, a remarkable saprophyte which
is destitute of chlorophyll.

The drawing shows the fungal sheath, and, to the right, the
epidermis and one cortical layer of the root. The black scales in the

1896.1 on the Circulation of Organic flatter. 165

sheath are dead cells in tLe root cap which remain held in the fungal
matrix.

All animals appear to be symbiotic, for we all carry about millions
of microbes which must fairly be regarded as junior partners in our
economy, and which we cannot do without. The microbe which has
been chiefly studied — the Bacterium Coli commune — apj)ears to be
essential for certain digestive processes which go on in the intestines
while we live ; and when we die this microbe is active in starting the
dead body upon that cycle of events which is one form of the " Circu-
lation of Organic Matter."

Now it is certain that the dung of all animals swarms with bacteria
and allied organisms when it leaves the intestines, and it seems highly
probable that excrement carries with it the biological machinery which
is necessary for its dissolution and ultimate humification.

My friend, Mr. George Murray, the keeper of the Botanical De-
partment of the British Museum, whose learning in fuugology is well
known, has kindly furnished me with an elaborate list of 139 genera
of fungi which flouiish on excrement.

Of these 139 genera Mr. Murray has tabulated no less than 628
species wliich are known to flourish on excrement.

Of the 628 species 226 have been found on the dung of more than
one genus of animals, but no less than 402 species of fungi are
peculiar to the excrement of only one genus of animals.

Of these 402 S23ecies of fungi 91 are peculiar to the dung of the
ox; 78 to the horse; 68 to the hare and rabbit; 30 to the dog; 25
to the sheep ; 28 to birds ; 21 to man ; 16 to the mouse ; 9 to the deer;
7 to the pig ; 7 to the wolf, and 22 to other animals.

This marvellous list is on the table for the inspection of those
who are learned in such matters.

This search for fungi in excrement is necessarily incomplete. In
Mr. Murray's list it is evident that the greatest number of species
have been found in the dung of animals which are domesticated and
common, and which offer facilities to the fungologist. The numbers
are startling, but when we consider that the dung of every living thing
which crawls or burrows, or swims or flies, has properties which are
peculiar to it, and which fit it to become the nidus of some peculiar
fungoid or bacterial growth, the part played by fungi in the distri-
bution and circulation of organic matter cannot be over-estimated.

The facts which have been recounted, and which seem to show that
fungi and bacteria are necessary for the growth and development of
even the highest plants and animals, and that fungi and animals are
equally necessary for the dissolution of organic matter, seem to point
to the conclusion that the correlation of the biological forces in this
world is no less exact than the correlation of the physical forces. The
uniform composition of the atmosj^here, except under special and
local conditions, is a fact which points in the same direction.

166

Professor G. V. Poore

[April 24,

BAI?LEy

PROOOCC PER ACRE

IH"

While it is impossible to over-estimate the debt which agriculture
owes to chemistry, we have, nevertheless, learnt from the bacterio-
logist that there are biological problems underlying the question of
fertility, and that a mere chemical estimation of the constituents of
organic manure is insufficient, by itself, to fix its manurial value.
It is by the agency of bacteria that organic matter is changed into
nitrates and other soluble salts, which are absorbed by the roots of
plants and serve to nourish them. This change only takes place
provided the temperature and moisture are suitable and the ground
be properly tilled. Drought and frost arrest the change, and excess
of moisture, by closing the pores of the soil, does the same thing.

Organic manures are economical in the long run, because if the
weather is adverse they bide their time until the advent of " fine,
growing weather." If one season prove unfavourable a large amount
of the organic matter remains in the soil to nourish the next crop.
This is not the case when soluble chemical manures are used.

That it is necessary to put dung uj)on the ground if we are to
maintain the fertility of the soil, has been the experience of all
peoples in every age.

I will now display a diagram which represents by a curve the

yearly produce of barley in bushels
per acre, grown continuously on the
same jDlots of ground for forty years,
but with this difierence, that one plot
(represented by the upper curve)
received 14 tons per annum per acre
of farmyard manure, while the other,
represented by the lower curve, has
been unmanured continuously (Fig. 1).
This diagram has been constructed
from figures given by Sir John Lawes
and Sir Henry Gilbert in the ' Trans-
actions of the Highland and Agricul-
tural Society of Scotland' for 1895.
I have replaced fractions by the
nearest whole figure. The fluctua-
tions of both these curves are very
great, and it will be noticed that
they are exactly parallel to each
other. This teaches us that weather
is the most important factor in agri-
cultural success, and shows the ex-
treme danger to the farmer of "placing
all his eggs in one basket," as has
been done by the so-called farmers of
the far West, who have attempted to grow wheat only by the process
of scratching the prairie without returning any dung to the soil, and
many of whom have been financially swamped by the first bad season.

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1896.] on the Circulation of Organic Matter. 167

Taking the average of tlie forty years, it will be found that the pro-
duce of the manured land averaged 49 bushels per acre per annum,
while the unmanured land gave only 16^ bushels.

I might have added to the diagram a third curve showing the pro-
duce of that plot of ground which, of all those manured with artificials,
gave the highest yield. The yield of this plot for the whole forty years
averaged 46 bushels, or only 3 bushels short of the average yield of
the plot treated with farmyard manure. If, however, we take the
average yield of the three plots for each of the four decades compris-
ing the forty years, the value of the organic matter becomes very
manifest. Thus the yield for each decade was with

Farmyard dung .. 44*9 51-5 50-0 51-6
Artificial manure .. 48-7 49-4 42-8 41*5
Unmanured.. .. 22-2 17-5 13-7 12-6

It will be observed that the yield from artificial manuring only
exceeded the yield from the farmyard jilot in the first decade, when it
showed an excess of 3 • 8 bushels. In the other three decades it was
deficient by 2*1, 7*2, and 10*1 bushels.

The deficiency of the unmanured plot in each decade, as compared
with the farmyard plot, was 22-7, 34-0, 37-3, and 39-0.

These figures are very convincing, and, as practical agriculturalists
seem to be now agreed that farming is hopeless without an adequate
amount of live-stock to furnish dung, no more need be said upon this
head.

But is there no danger in using organic refuse, which may be
infective and dangerous, as an application to the land ? To this I
should say emphatically " No," provided it be put in the upper layers
of the soil, and the soil be tilled. Oiu* organic refuse, when allowed to
putrefy in water, and to trickle under pressure to our wells, or run
direct into our sources of drinking water, has turned millions of
pounds into the pockets of members of my profession, but when
rationally used as a top dressing for the well-tilled soil, it has never,
that I am aware of, produced any harm.

I have tried to investigate this matter. Some five years ago I
constructed a well five feet deep in the middle of a garden which is
plentifully manured with all that is most loathsome to our senses.
This well is lined to the very bottom with concrete pipes, further
protected by an external coating of concrete ; the junctions of the
pipes are securely closed by cement, and there is a good parapet and
efficient cover.

This well is shown in plan and section in the diagram, which I
will throw upon the screen (Figs. 2 and 3).

Now no water can possibly enter the well, except through the
bottom. The water in it is clear and bright, and since its construc-
tion no mud has collected on the bottom. The sides of the pipes
also remain absolutely clean, so much so that when, last summer, I

168

Professor G. V. Poore

[April 24,

fihowed this well to a party of scientific friends, some of them dropped
a hint that it had possibly been scrubbed in honour of their visit.
This, however, was not the case.

The water from this well has been examined three times chemi-
cally, with the result that it has been pronounced free from organic
impurities, and three bacteriological examinations have been made

with the result of showing a bacterial
purity, which is quite exceptional.
The last examination was made by
Dr. Cartwright Wood in November,
1895, and showed a very high degree
of bacterial purity. The water was
specially examined by Dr. Wood for
the presence of Bacterium Coli com-
mune, but with negative results.
Dr. Wood writes : " The results are
exceedingly satisfactory, and I must
admit surprised me very much." A
surface-well on this pattern has
lately been constructed in a neigh-
bouring village, and the results, as
far as the appearance of the well
and water are concerned, seem to bo
entirely satisfactory.

Fig. 2.

Plan of well, showing its relation
to paths and hedge.

Fig. 3.

Section of well, showing concrete
lining and position of pump.

When people live crowded to-
gether in cities, the difficulties con-
nected with the cleaning of the
houses is very great. After the in-
vention of the steam-engine it was
found possible to supply even the
top floors of the highest houses with
an ample supply of water. We ac-
cordingly abolished the scavenger,
and adopted a complete system of water-carried sewage. In this way
our houses have been cleansed, and our rivers and surface-wells have
been fouled, and it is difficult to say whether at 2)resent there be a
balance of advantage or disadvantage. We have had epidemics of
cholera and of typhoid, and it is almost certain that there is no
one here present but has suffered in some way or another from the
" drains."

The greatest drawback of this system is the fact that it
encourages overcrowding of houses on inadequate areas, and, un-
fortunately, it is this fact which has rendered the system so popular.
With water under pressure there is no need to provide houses with
any back-door or back-yard, and there is no inconvenience in having
excessively high buildings. The speculative builder, who has been
relieved of all responsibilities in connection with sewage and water

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170 Professor G. V. Poore [April 24,

supjDly, lias abundantly used his opportunities, and the happy ground-
landlord has sold his land at large prices per square foot. We are
shutting out the light and air more and more from our cities, and the
crowding in the streets is making locomotion in them difficult. This
overcrowding is a serious matter, and I will show you what it means
in London by throwing on the screen a table and diagrammatic plan of
the sanitary areas of London, with the mortality figures in the years
1892 and 1893, as calculated by Mr. Shirley Murphy after due
correction for abnormalities of age and sex distribution (see the
preceding page).

This table and plan shows at a glance that the mortality of
London as a whole (taken as 1000) is fourteen or fifteen per cent,
higher than that of England and Wales, and that, while some of the
outlying districts, such as Hampstead, Lewisham, and Phimstead,
liavc a mortality below that of England and Wales, the areas near
the centre of London are all considerably above it ; and some,
such as the Strand, Holborn, St. George's-in-the-East, and White-
chaj)el, have a mortality as high as that of the worst manufacturing
towns.

The danger of overcrowding is well shown by the explosive
outburst of small-pox in Marylebone in 1894.

I will throw upon the screen a photograph of part of the Asylums
Board Map in which each case of notified small-pox is shown by a
black dot (Fig. 4). This map shows that the outbreak was limited
to two spots, one in Portland Town and one round Nightingale
Street, Edgware Eoad, where the density of population, according to
Mr. Charles Booth, is over 300 i)ersons to the acre.

The other maps show that, whereas the air-borne contagiura,
diphtheria, was confined more or less to the crowded districts, en-
teric fever, which is a water-borne contagium, was evenly spread
over the whole parish. It need hardly be said that the enforcement
of vaccination, notification, and isolation, are important in proportion
to the density of population. The working of the sanitary laws is a
great expense to the ratepayers. I find it stated, for instance, in the
report of the Asylums Board, that for the removal of the 260
small-pox patients from Marylebone, the ambulances travelled nearly
twenty miles for each patient, and collectively 5200 miles, or about
the distance from here to Bombay. Overcrowding is not cheap, and
I find, by a reference to the report of St. Marylebone, that whereas,
in 1871, that parish, of about 1500 acres, and with a diminishing
population, could be " run " for about 6601. a day, it now costs about
1100/. per day. It is right to add that the parish has no control over
a great part of the expenditure, but, nevertheless, 410/. per diem is a
fair sum to place upon the shrine of progressive municipalism.

If infectious disease occurs in our houses we have only to notify,
and the parish does the rest. We have j^ut a premium on fever, and
the lucky man whose house is visited by a mild scarlatina is rewarded
by having his family maintained for six weeks at the public expense

1896.]

on the Circulation of Organic Matter.

171

and bis whitewashing done by the parish. If, on the return of a
child from the hospital, another child catches the disease, be can
recover damages.

Fig. 4.

The Asylums Board is probably the most pauperising institution
ever conceived, but we are such cowards in the presence of disease
that financial and moral considerations have but little weight, pro-
vided the imclean be removed.

Another great drawback to the water-carriage system of sewage is
the increasing difficulty with regard to water supply. Our needs per

172 Professor G. V. Poore [April 24,

head per diem in tlae matter of water have gradually increased to
something like forty gallons, which many experts consider to be none
too much. In London the air is so foul that rain-water is valueless
for domestic use, and the water of the surface wells is too poisonous
to drink, because we have neglected what I believe to be the most
important of the principles of sanitation, viz. the keeping of organic
refuse, whether solid or liquid, on the surface. The humus is the
most perfect purifier and the best of filters, in virtue of its physical
conditions and the life that is in it. We deliberately take our filth
to the under side of the filter, and then complain because our surface
wells are foul. The Water Companies are masters of the situation.
Water is not paid for, as a rule, in proportion to the quantity used,
because Parliament in its wisdom has decided that thriftiness in the
use of water is wicked. The grossly overburdened ratepayer is now
pricking up his ears to listen to the j^rattle about Welsh water
schemes at a cost of 38,000,U00Z., and is congratulating himself that
he is only a leaseholder, and that his bondage is terminable in seven,
fourteen or twenty-one years at most. Water carriage, in which the
carrier is some sixty times more heavy and twenty times more bulky
than the thing to be carried, is economically ridiculous (except in
places where nature has provided enormous quantities of water), and
involves every place where it is tried in ruinous debt. Let us take
an illustration.

A suburban district having 27,000 persons on 7000 acres of land,
or a population of less than four to the acre, mainly engaged in market
gardening, has in the last ten years borrowed 106,442/. for sewerage
works. The only visible result to the inhabitants is that even coun-
try roads, with houses at ^-mile or J-mile intervals, have been dotted
with foul smelling manholes.

In 1894-5 the sum of 18,534Z. 14s. 1^. was raised from rates, and
of this there was spent 6518/. 13s. lOd. for interest and reiDayment of
sewerage loans, and 2542Z. 3s. llfZ. for current expenses in connection
with sewage. If to this be added one-third of the establishment
charges (say 700Z.), we reach a total of 9860Z., or more than half the
sum received from rates.

The provision and maintenance of all the patent domestic gim-
cracks which water carriage involves, together with the necessarily
increased bills for water paid by the householder, would probably
double that sum, and we shall not be far wrong in saying that these
27,000 persons are spending 20,000Z. a year for the purpose of
throwing their capital into the Thames.

This doubling of rates has most seriously crippled the chief
industry of the district, and the market gardeners feel severely the
heavy extra charges which they are called upon to pay. These
gentlemen by putting much of the offal of great towns to its proper
use, and converting it into food and wages for the poor, are doing a
great work, but they are in a fair way to be ruined by the silly reck-
lessness of our local governors.

1896.] on the Circulation of Organic Matter, 173

On December 3, 1895, a writer in The Times pointed ont that in
1895, as compared with 1890, 633,000 acres of land were either ont
of cultivation or had been converted to " permanent pasture," a term
which implies a minimum cultivation. Of these lands there were in
Essex over 31,000 acres, in Kent nearly 30,000, in Surrey 15,000, in
Sussex 29,000, in Berks 20,000, in Bucks 11,500, Herts 7600, Mid-
dlesex 5500.

It is a noteworthy fact that in the eight counties nearest London
which provides for them an insatiable market, nearly 150,000 acres
of land should have glided out of cultivation in the last five yeais.
It is impossible not to believe that the local rates in places near
London are the last straw upon the back of the agriculturist, who is
ruinously taxed in order that his land may be starved. To show
what suburban agriculturists have to bear in the way of local taxation
I will quote from my little book, ' Essays on Rural Hygiene,'* a
few figures showing what is paid by a gentleman who farms 200 acres
of land, of which 15 are grass : —

£ s. d.

Income Tax (at 6c?.) 47 4 9

Land Tax 24 16 8J

Poor Eate .. .. 123 0 5

Burial Eate 19 13 8

District Eate 83 1 11

Tithe (considered low) 15 11 4

£313 8 91

The social problems of the present day are many and complicated,
and all of us have heard of " Distressed Agriculture," " Pauperism,"
" The Aged Poor," and the " Unemployed,"

The agriculturist, who is being burdensomely taxed in order that
his land may be starved, is apparently to have his rates paid for him
out of the Imperial Exchequer. No one who knows the straits he is
in will grudge him this relief. But the paying of local charges out
of Imperial taxes has the inevitable result of making our " Local
Boards " more and more extravagant, because they have the spending
without the trouble of raising money.

The reform most needed in the interest of the agriculturists and
others is to put an effectual check upon the extravagance and osten-
tation of Local Boards and District Councils, and to see that they
spend no more money in any one year than they can raise in their
districts. These bodies are now obliged to submit their accounts to
a proper audit and to publish them, and it is hoped that the ratepayer
will subject them to close criticism.

The policy of allowing persons who are elected for three years to
raise loans and plunge a district into debt for a period of thirty years

' Essays on Kural Hygiene,' 2nd ed. 189-i, Longmans.

174 On the Circulation of Organic Matter. [April 24,

without one iota of personal responsibility is obviously dangerous.
To allow reckless borrowing for the construction of works which are
a source of expense and waste and never of profit, would be called
madness in private life.

Doubtless a seat on a Council which borrows money in lots of
100,000Z. at a time affords a delightful amusement to the idle man,
the busy-body, the faddist, the philanthropist with a mission for
fumbling in other persons pockets, and the prophet who is ever
anxious to borrow in order to provide for the future of which he is
ignorant. Your prophet is the most dangerous of these persons, and
instances will occur to the minds of most of us of municipalities
which have been half ruined by over sanguine persons endowed with
speculative minds and persuasive tongues. The risks run by these
persons is so small, be it remembered, that if an aggrieved ratepayer
makes them defendants in an action they enjoy the unique privilege
of paying j)art of their costs and damages out of the successful
plantiff's pockets.

Most of the local borrowing in this country has been for works
of sewerage, and although such works are financially ruinous we are
told that we get a dividend of " Health." This, however, is not true,
at least in London, and nobody could expect health to emerge
from a system of which putrefaction and overcrowding arc the chief
characteristics.

The application of organic matter to well-tilled soil leads to
positive gain and definite increase. The soil is the only permanent
source of wealth in this world. And we are all of us absolutely
dependent upon it for existence and happiness. The soil, if properly
tilled, provides health as well as wealth, and be it remembered that
in proportion to its productiveness so is the need of labour; and
further, be it remembered that long after the eye is too dim and the
hand too slow to keep time with steam machinery, the physical powers
are amj^ly sufficient for the cultivation of the land.

Many of our pressing social problems are inextricably linked
with our duty to the soil, and any country in which the fertility of
the soil does not increase cannot be rightly regarded as really in the
van of civilisation and scientific progress. We are probably the
wealthiest country on the globe, because for some time past we have
been the hub of the entire financial world. Our success in one
direction is no excuse for neglecting the more certain sources of
wealth, and it is to be hoped that it will soon be regarded as evidence
of neglect of our moral obligations to allow the land to drift out of
cultivation.

[G. V. P.J

1896.

Auuual Meeting.

175

ANNUAL MEETING,
Friday, May 1, 1896.

Sir James Crichton-Browne, M.D. LL.D. F.E.S. Treasurer and
Vice-President, in the Chair.

The Annual Report of the Committee of Visitors for the year
1895, testifying to the continued prosperity and efficient management
of the Institution, was read and adopted.

Seventy-two new Members were elected in 1895.

Sixty-three Lectures and Nineteen Evening Discourses were
delivered in 1895.

The Books and Pamphlets presented in 1895 amounted to about
280 volumes, making, with 594 volumes (including Periodicals bound)
purchased by the Managers, a total of 854 volumes added to the
Library in the year.

Thanks were voted to the President, Treasurer, and the Honorary
Secretary, to the Committees of Managers and Visitors, and to the
Professors, for their valuable services to the Institution during the
past year.

The following Gentlemen were unanimously elected as Officers
for the ensuing year :

President — The Duke of Northumberland, K.G. D.C.L. LL.D.
Treasurer — Sir James Crichton-Browne, M.D. LL.D. F.R.S.
Secretary — Sir Frederick Bramwell, Bart. D.C.L. F.R.S.
M. Inst. C.E.

Managers.

Sir Frederick Abel, Bart. K.C.B. D.C.L. LL.D.

F.R.S.
Sir Benjamin Baker, K.C.M.G. LL.D. F.R.S.
John Wolfe Barry, Esq. C.B. F.R.S. M. Inst. C.E.
The Right Hon. Lord Halsbury, M.A. D.C.L.

F.R.S.
Charles Hawksley, Esq. M. Inst. C.E.
John Hopkinson, Esq. M.A. D.Sc. F.R.S.
Victor Horslev, Esq. M.B. F.R.S. F.R.C.S.
William Huggins, Esq. D.C.L. LL.D. F.R.S.
The Right Hon. Lord Kelvin, D.C.L. LL.D. F.R.S.
Alfred B. Kempe, Esq. M.A. F.R.S.
George Matthey, Esq. F.R.S.
Ludwig Moud, Esq. Ph.D. F.R.S.
Sir Andrew Noble, K.C.B. F.R.S. M. Inst. C.E.
The Right Hon. Earl Percy, F.S.A,
Basil Woodd Smith, Esq. F.R.A.S. F.S.A.

Visitors.

Gerrard Ansdell, Esq. F.C.S.

Sir James Blyth, Bart.

Arthur Carpmael, Esq.

Sir William James Farrer, M.A. F.S.A.

Carl Haag, Esq. R.W.S.

Sir Francis Laking, M.D.

Hugh Leonard, Esq. M. Inst. C.E.

James Mansergh, Esq. M. Inst. C.E.

Lachlan Mackintosh Rate, Esq. M.A.

Felix Semon, M.D. F.R.C.P.

Henry Virtue Tebbs, Esq.

John Isaac Thornycroft, Esq. F.R.S. M. Inst. C.E,

Thomas Tyrer, Esq. F.C.S. F.I.C.

John Westlake, Esq. Q.C. LL.D,

James Wimshurst, Esq,

176 Chronographs and their Application to Gun Ballistics. [May 1,

WEEKLY EVENING MEETING,

Friday, May 1, 1896.

William Crookes, Esq. F.R.S. Vice-President, in the Chair.

Colonel H. Watkin, C.B. E.A. 31.B.I.

Chronographs and their Application to Gun Ballistics.

The lecture I have had the honour of being asked by the Council of
this Institution to give to-night, is on a subject in which I have taken
great interest and worked at for the last twenty-five years. ^ There is
a fascination in being able to record minute portions of time which
our senses are not able to discriminate. It is easy to talk about
the millionth of a second, but it is hard to realise how small this is.
To try and convey some idea of this, supposing a man were to work
eight hours every day, Sundays excepted, for close upon seven years,
one-millionth of his working time during that period would be
represented by ono minute. The instrument which I hope to show
you at work this evening records to that accuracy when working at
tbe highest speed. The objects I had in view in designing the appa-
ratus are twofold. First, the measurement of the velocity of a
projectile outside the gun, or external ballistics. Secondly, the
measurement of the velocity of a projectile at dififerent parts of the
bore of a gun, or internal ballistics. The first is useful for comparing
the relative power of different guns, merits of different powders, and
for determining the resistance of the air. The second for ascertain-
ing the pressure exerted at different parts of the bore by different
natures of powder, from which the shape of the gun is determined.
I dare say you have all noticed the very different shapes of modern
guns from those of a few years ago. This difference is due to the very
different behaviour of the powder, or rather propellant, now employed,
as one can hardly talk of cordite as powder.

I propose this evening to very briefly describe some of the older
forms of chronographs, and more minutely describe those on the table,
which I have designed for experiments in ascertaining the velocity of
a shot passing through the bore of a gun.

The subject divides itself into two principal parts : —

1. The apparatus for measuring minute portions of time.

2. The appliances for utilising these instruments for ballistic
purposes.

1896.] on Chronographs and their Application to Gun Ballistics. 177

The first I will further subdivide into two parts : —

(a) Instruments depending upon the action of gravity.
(h) Instruments liaving revolving drums

The latter into —

(c) Appliances for ascertaining external ballistics.

(d) Appliances for ascertaining internal ballistics.

The lecturer here described, with the aid of lantern slides, several
instruments which had been used for ballistic work, such as Navez-
Leur, Boulenge, &c.

About the same time as the Boulenge was introduced, I designed the
instrument shown in Fig. 1. In this a weight drops freely in air,
and the registration does not, as in the Boulenge chronograph,
commence from the moment of its liberation, but during its fall, thus
avoiding any inaccuracy of residual magnetism in the electro-magnets,
from the fact that registration takes place during the fall. When
small portions of time have to be measured, the experiments may be
so arranged that the weight under the accelerating force of gravity
shall have acquired a considerable velocity before registration com-
mences. Also the time of passing several screens can be recorded.

The instrument consists essentially of two upright brass cylinders
revolving on pivots, those at the bottom being fixed, while the two at
the top consist of screws to allow of the cylinders being removed.
The cylinders are carefully insulated from one another, and connected
with two binding screws on the base board. On the bed of the instru-
ment are two levels at right angles to one another, by which, with the
aid of three levelling screws, the cylinders may be placed truly
vertical. Close to but not quite touching the cylinders are scales
divided into thousandths of a second, which by means of a peculiar
vernier subdivide these into hundred-thousandths of a second. On the
top is an electro-magnet which serves to hold up the weight equi-
distant between the two cylinders.

The weight has two sharp points which nearly, but not quite, touch
the surface of the cylinders.

The action of the instrument is simply this. The weight being
released a short time before the gun is fired, descends between the
cylinders ; the shot on passing through the first screen breaks the
continuity of the primary wire of an induction coil, thus causing an
induced spark to pass from one cylinder to the other through the brass
wire of the weight. As the cylinders are smoked, a minute spot
registers the exact position of the weight at that moment. The
weight continuing to fall, as the shot passes the second screen (the
primary current in the meantime having been re-established) the same
result follows ; and so on for any number of screens. The distances
between the spots, as read off from the velocity scale, give the time
of the shot passing the various screens.

By means of a calculating scale the velocity may be determined
for any distance between the screens. For a second experiment the

Vol. XV. (No. 90.) n

178

Colonel H. Wathin

[May 1,

drums are slightly revolved so as to present a fresh smoked surface
for the records, and the weight again suspended, and so on.

The instrument can be used for accurately determining the speed

Fia. 1.

1896.] on Chronographs and their Application to Gun Ballistics. 179

of revolving cylinders ; also to demonstrate the accelerating force of
gravity. Thus, having attached the secondary wires of a coil to the
binding screw, and set the vibrating spring in action, a stream of
sparks passes through the suspended weight, the rapidity, which is due
to the note given out by the vibrating spring, being so great that to
the eye it appears as one continuous stream of light. But if the
weight be now dropped the sparks appear down each cylinder, opening
out as the weight descends. Each of these sparks gives its record on
the cylinders, and if they are read off by means of the velocity scale,
you will see that they are equi-distant as regards time but vary as to
linear distance. They follow the well-known law,

An interesting experiment is simply made to test one's personal
equation, and to show the comparatively long time it takes for a
message to be sent from the brain to the fingers. Thus, if I press
this key, which breaks the primary circuit, the moment I see the weight
begin to fall, the induced spark will record the time it has taken to
perform this operation.

We now pass on to instruments having revolving drums, the
circumferential speed of which can be made much greater than the
dropping weight, or plumb-bob, of the instrument I have described.
Prof. Bashforth's is a notable example, and one which did much good
work in experiments for ascertaining the resistance of the air to
projectiles.*

After many years' work, designing and constructing chronographs
for experimental purposes, I devised the instrument shown in Fig. 2,
and the system of plugs, &c., with which I have been taking the travel
of shot up different guns during the last two or three years. In this
a large drum, made as light as possible consistent with strength, is
carefully mounted between coned centres. And here I may mention
an incident for the benefit of others, which might have had serious
consequences to myself. In the smaller and lighter instruments I had
previously employed, I had hard steel bearings v/orking into hard steel
centres, and found no difficulty with them, and I therefore employed
the same in this instrument. But one day, notwithstanding careful
lubrication, the two metals seized, and the drum, which was revolving
at a high speed, was quickly brought to a standstill and pulled out of
its bearings. I of course turned off the current at the first alarm, but
it was fortunate for me that the support held the drum. I now
employ No. 7 phosphor bronze, and all works smoothly ; at the same
time I do not neglect lubrication. This drum is revolved by means
of a motor, and this I consider a great advantage over any other
method, inasmuch as the drum can be driven at a very high speed, and

* Description was here given of Professor Bashforth's chronograph and the
Noble chronoscope .

N 2

180

Colonel H. WaiMn

[May 1,

kept for some time running uniformly. With geared mechanism this
is impossible, even though the greatest care is taken, as in the case of

1896.] on Chronographs and their Application to Gun Ballistics. 181

the Noble chronograpli, to grind tlie roughness out of the mechanism
by running it for some time.

On a hinged frame of ebonite are placed a row of forty steel-pointed
pins, screwed into the ebonite so as to allow of accurate adjustment.
The frame is brought up to a fixed stop, and clamped by means of
two cam clutches. Each pin is carefully adjusted, to be at a uniformly
small distance of about -^^q- inch from the surface of the drum. The
ebonite frame is capable of traversing from right to left, so that each
point is opposite a different surface of the drum, for the convenience
of making a series of experiments without re-smoking the drum.
Each pin is connected by insulated wires with a binding screw on the
bed-plate. On the left edge of the drum is a carefully divided circle,
reading by means of a vernier to minutes of angle, and with care to
half this accuracy.

Wires run from the secondary poles of a series of induction coils
to these binding screws. Thus 1 and 2 binding screws are connected
with No. 1 coil, 3 and 4 to No. 2 coil, &c. In this way I have two
records on the drum for each primary circuit. The primary circuits
of the coils are connected with plugs (which I shall presently describe)
screwed into the gun.

Now we come to a very important part of the instrument, viz. the
means of timing the speed of the revolution of the drum. In my first
experiments, years ago, I employed the usual method so much in vogue
then and now, viz. tuning forks. A tuning fork, as you know, vibrates
so many times a second according to its note. Thus, for instance, the
middle C corresponds to 256 double vibrations in a second. To employ
these a small stylus is fixed to the tuning fork, which presses lightly
on the drum ; as the drum revolves a sinuous line is formed by
scratching off the smoked surface. I found, however, by careful trials
that you could not depend on these records, owing to different atmo-
spheric conditions and the varying surfaces of the drum. Nor does
this seem unreasonable when we look into the matter. In the first
place the vibrations of a fork are affected by temperature and baro-
metric pressure ; these are more or less known and could be allowed
for. We might also correct for the additional weight of the stylus,
but it seems to me more difficult, nay impossible, to say what the
vibrations are under the friction of the stylus on the surface of the
drum with varying thickness of carbon deposit. Moreover the
trouble of working out of the tuning fork records is considerable;
and with the circumferential speed necessary for recording millionths
of a second, forks with a very high note have to be employed A fork
giving the middle C, before mentioned, would be useless for this
purpose, but the higher the rate of vibration the greater would be the
retarding effect of the stylus recording the vibrations.

The stop watch arrangement employed by Sir Andrew Noble is
not applicable to this instrument, nor is it, I think, a very accurate
method of timing.

I have, after many failures, worked out a method which experience

182

Colonel H. Watkin

[May 1,

shows is very reliable. In this I depend on a very constant quantity,
viz. gravity. A weight is dropped from a given height, and in its fall
breaks two screens one after the other. Knowing the distance the
weight has to fall to the first screen, and the distance between the
screens, it is easy to calculate the time it has taken for the weight to
pass from the one screen to the other.

The screen is made thus — see Fig. 3. A piece of hardened watch
spring A B, is pivoted in a brass frame B C, and capable of being
held up and pressed very lightly against the support D, so that two
pieces of platinum, one on the spring and one on the support, are
kept in contact. The fall of the weight E breaks the contact. An
exactly similar arrangement, A' B' C D' is placed about 3*77
inches below the top spring. Each screen is connected to the
primary wire of an induction coil, the secondary being led to the
recording points opposite the drum of the chronograph. It follows,
then, that the moment the weight touches the
first screen, a spark passes on the drum from
the steel points. The drum goes on re-
volving, and the weight continues to fall until
the second screen is reached, when again a
spark passes. The distance between the two
spots measured on the graduated circle, and the
known time taken by the weight to pass the
screens, gives the speed of the drum. The time
taken for the weight to fall below the screens
was '01894:8 second. As the result of a trial
before a committee, in which the record of two
weights was made on a rapidly revolving cy-
linder, the variation did not exceed 0*16 per
cent. To test whether the weights were appre-
ciably retarded by breaking the screens, a third
screen was inserted between the weight and the
first screen, and it was found that there was no
appreciable retardation. As a precaution I al-
ways employ two drop weights with entirely
independent circuits, so as to avoid the chance
of an experiment being wasted, from the pos-
sible failure of one ' of the screens not acting
through a bad contact; but I nearly always
obtain the double record.
The next difficulty I encountered in my experiments was the
means of reading the record of the sparks. Some days we might get
nice small records by carefully adjusting the strength of the current.
Another day the records would be much too large for any accuracy.
I tried every conceivable method of smoking, from the carbon de-
posited by gas flame, to that deposited by various kinds of oils, and
also that of burning camphor, but could not be certain of my records
being readable. I may here mention that for accurate experiments.

Fig. 3.

1896.] on Chronographs and their Application to Gun Ballistics. 183

covering the drum with paper is out of the question ; for the spark,
taking the line of least resistance, goes through the thinnest part of
the paper, which may or may not be directly opposite the points at
the moment the spark occurs. "When extreme accuracy is not
required, paper may conveniently be employed, as the paper, on being
removed and varnished on the back, may be kept as a record of the
experiment for future reference and measurement.

The difficulty of obtaining a uniformly smoked surface giving a
minute centre for exact reading has been overcome by the following
simple means. A small lump of paraffin wax about the size of the
tip of one's little finger is dissolved in half a pint of benzole ; a rag
saturated with this solution is rubbed over the drum. The drum is
smoked with a large flat wick saturated with a moisture of equal parts
of paraffin oil and rape seed oil. The nature of the records obtained
can be varied at will, according to the amount of wax dissolved in
the benzole, but all have a distinctly defined minute centre, which
can be read to the greatest nicety. The method adopted of reading
the records, is to stretch a fine hair in the centre of a brass frame,
fitting with steady pins the supports of the drum centre. The hair
is so arranged as only just to clear the surface of the drum. A
magnifying glass enables one to bring the record marks exactly under
the stretched hair.

We now come to the application of these instruments for measur-
ing gun ballistics. For external ballistics the usual screen is a
series of copper wires stretched across a wood frame. The cutting of
this wire breaks the circuit and gives the record. There is no doubt
that the cutting of a wire in this manner is not perfectly accurate,
and to a slight extent would vary with the size of the screen ; but
for ordinary work of getting the muzzle velocity of a shot, when
the screens are placed 120 feet or more apart, it is sufficiently good.
Bashforth employed a different form of screen, as he required the
circuit to be remade immediately the shot had passed through. In
this a spring, whose play was limited by a hole in a copper plate, was
held down to the lower surface of the hole by a weighted thread.
As the thread was cut the spring, rising to the top of the hole, broke
the circuit and remade it. In this method, as I have experimentally
proved, the breaking of the circuit is not very exact, but near enough
when the screens are far apart, I employed a somewhat similar
arrangement with my drop-weight chronograph, only using broad flat
springs to avoid the rubbing of the spring against the side of the hole,
which sometimes occurred in the Bashforth screens.

For internal ballistics when we have to measure the passage of a
shot over plugs placed two inches apart, the utmost accuracy of break
is required. Sir A. Noble used a cutter plug which severed a wire
as the shot forced up an inclined plane. Unless the shot exactly fits
the bore, which of course with the ordinary projectile it does not,
considerable errors arise from the use of such cutter plugs, as we
never know the exact position of the shot when the wire is actually

184

Colonel H. WatJcin

[May L

severed. After trying several methods, the following, which has
proved most satisfactory, was worked out. A soft steel wire. Fig. 4,
A B C, bent as shown in this diagram, has the bent portion B hardened
at two points, where it projects from the plug into the gun. The
wire is covered with india-rubber tubing to insulate it from the plug,
and a plug of asbestos packing D, pressed hard by a screw piston
E, prevents any escape of gas. After the first
experiment we found the compressed air in front
of the projectile pressed the wire away from the
breech and altered its position very slightly;
so now boxwood ferrules are placed over the wire
instead of the rubber tube, for a short distance
from the bottom of the plug. The holes in the
gun are bored spirally round the gun, so as not
to weaken it in one line. The gun we have been
experimenting with is really a 7-inch gun, with
a bore of 4*7 inch diameter, and 60 calibres long.
The great length gives us the opportunity of
ascertaining what gain in muzzle velocity is
obtained by additional length. Some of the
plugs at the breech end where the rise of pres-
sure is very rapid, are only 2 inches apart, the
distance increasing towards the muzzle where
they are 20 inches apart. Here the pressure is
comparatively small, but the velocity of the shot
is very great.

The sketch, Fig. 5, shows the arrangement
of wires from the different parts of the appa-
ratus. Only a few wires are shown to avoid
confusion.

Here the lecturer showed the working of the whole apparatus,
firing a pistol to break a series of screens representing the bore of a
gun. Eecords were obtained on the drum of the breaking of the
screens by the bullet, and the speed of the drum was determined by
a drop weight, similar to that shown at Fig. 3.

The readings obtained on the divided circle are translated into
time, and plotted on a very large scale in the Koyal Gun Factory,
and the velocity and pressure curves calculated. Here is a specimen
of the curve. The working out of a round is a laborious affair,
taking about a fortnight.

Now it may be rightly asked — How do we know that the records
on the drum are true ? Are the cutter plugs reliable, and the records
given by the induction coil accurate ? To test the question of the
cutter plugs, two plugs were placed, one on the top side of a gun,
and one on the bottom side, but at exactly the same distances from the
muzzle. The circuits for these were entirely distinct. On firing the
gun identical records were obtained. Now as regards the records of
the sparks, whether they vary, and how long after the rupture of the

Fig. 4.

1896.] on Chronographs and their Application to Gun Ballistics. 185

primary does the secondary occur, miglit I suppose be tested by means
of the revolving mirror — but this would not have been entirely satis-
factory, inasmuch as it would not have tested the actual record on the
drum. So I devised the following, which, though apparently very simple,
requires care to get good results. On the rim of the drum I insert a
piece of ivory. Fitted to the bed-plate is a hinged piece of brass
whose far end presses against the rim of the drum. The circuit from
the primary wire of an induction coil runs through the brass piece
and the drum, except when it is interrupted by the ivory. A sharp
break here occurs, which leaves its record on the drum by means of
the steel pins and secondary current, as before described. If the
drum is revolved slowly, the spark will give the true position at
which the ivory breaks the circuit. If, now, there is any retardation
or delay in the record of the spark, it will be shown on the drum
when it is rotated rapidly — the record lagging behind that obtained
by the slow break. Knowing the speed of the drum, the time of
retardation can be obtained.

Fig. 5.

I have made several of these experiments. On the table are some
of the records . To test the variability of the records, it suffices to
move the recording points along the drum at each break, when the
records should be in a straight line. These specimens will show you
how accurate they are. Great care must be exercised to turn the
rim perfectly true and smooth ; also the brass piece rubbing against it
must be often smoothed up.

The measurement of these retardations is a delicate matter, as we
are dealing with a retardation of only 10 millionths of a second.
I think that the improvements I have carried out in these instru-

186 Colonel H. Watkin on Chronographs. [May 1,

ments now enable us to obtain records of the passage of a shot up
the bore of a gun to an accuracy closely approaching the millionth
of a second.

There is one thing, however, we have failed so far to get, and that
is the velocity of a shot immediately outside the muzzle of the gun.
There is no doubt that for a short space of time the shot is accelerated,
but how far the acceleration extends is not known.

To try and obtain this we had a strong steel bar fastened to the
muzzle and projecting some 10 feet from it. In this were screwed the
same kind of plugs as those I have already described, only that the
steel wire was of much stouter gauge. The experiment was, however,
a failure. The two plugs that were cut just before the tail end of
the shot left the bore were properly recorded, but the moment the
shot cleared the bore, the blast rushing past the shot caused irregular
results.

Three years ago I proposed another method, which is just about
to be tried, viz. that the drum of the chronograph be covered with a
sensitive photographic film, the whole apparatus to be enclosed in a
box and fitted with a lens. In the gun is a shot filled with magnesium
composition ; this is ignited electrically just before the gun is fired.
As the drum with the film will be in rapid revolution, I hope to get a
streak of light impressed on the film by the magnesium shot as it
leaves the gun. This will form a curve which, from the known
speed of the drum, will give the exact speed of the shot at every moment
from leaving the muzzle to a distance of 20 or 30 feet in front of the
gun. From a small experiment I made in my workshop this seems
hopeful,* as I obtained a streak of light across a photograpic plate,
from a magnesium torch fired from a pistol.

A useful adaptation of the revolving drum is to ascertain the
velocity of recoil of rifles and guns, &c. Across the drum is a slide,
which runs along a groove and presses lightly on its smoked surface.
As the slide is pulled by the recoil, the drum at the same time
revolving at a known speed, we get a curve which gives the velocity
of the recoil at every moment.

I tried in this way to get the curve of the first start of a shot in
the 12 pr., a steel wire being fastened to the shot, and led through the
breech block to the chronograph placed on the carriage immediately
behind. The result was a failure, as the wire broke almost immediately.
This possibly might have been got over by thicker wire had the
experiment been carried on.

* Since the lecture some of the experiments have taken place, and show that
most distinct records can be obtained in this way. The twist of the shot is also
shown, as there were two exits in the shell.

[H. W.]

1896.] General Monthly Meeting. 187

GENERAL MONTHLY MEETING,

Monday, May 4, 1896.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in tlie Chair.

The following Vice-Presidents for the ensuing year were
announced : —

Sir Frederick Abel, Bart., K.C.B. D.C.L. LL.D. F.R.S.

The Right Hon. Lord Kelvin, D.C.L. LL.D. F.R.S.

George Matthey, Esq. F.R.S.

Ludwig Mond, Esq. Ph.D. F.R.S.

The Right Hon. Earl Percy, F.S.A.

Basil Woodd Smith, Esq. F.R.A.S. F.S.A.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer.

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Hon. Sec,

J. H. Badcock, Esq. M.R.C.S.

F. J. Bennett, Esq.

Dugald Clerk, Esq. F.C.S.

William John Gow, M.D. M.R.C.S.

John Cameron Graham, Esq.

Mrs. Edward Patten Jackson,

Sir John Jackson, F.R.S.E.

Lady Jackson,

William L. Jordan, Esq.

J. William Mackean, Esq. F.C.S.

John S. Mackintosh, Esq.

Julius Moeller, Esq.

Thomas Oliver, M.D. F.R.C.P.

Sir Frederick Pollock, Bart. M.A. LL.D.

Harry F. Pollock, Esq. M.P.

Colonel Sir Charles Euan-Smith, K.C.B. D.C.L.

James Swinburne, Esq. M.Inst.C.E. F.C.S.

Arthur J. Walter, Esq. LL.B.

Edward Weldon, Esq.

were elected Members of the Royal Institution.

The Right Hon. Lord Rayleigh was re-elected Professor of
Natural Philosophy in the Royal Institution.

188 General Monthly Meeting, [May 4,

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for tho same, viz. : —

FKOM

TJie Lords of the Admiralty — Greenwich Meteorological Keductions. Part 3,

Temperature, 1841-90. 4to. 1895.
Accademia dei Lincei, Reale, Roma — Classe di Scienze Fisiche, Matematiche e
Naturali. Atti, Serie Quinta ; Rendiconti. 1° Semestre, Vol. V. Fasc. 7.
8vo. 1896.
Andomj B. (the Author) — Industrial Explorings in and around London. 8vo.

1896.
Asiatic Society of Bengal— J ouTual, Vol. LXIV. Part 1, No. 3; Part 2, No. 3.

8vo. 1895-96.
Asiatic Society, iJoyaZ— Journal for April, 1896. 8vo.

Astronomical Society, Boyal— Monthly Notices, Vol. LVI. No. 6. 8vo. 1896.
Bankers, Institute o/— Journal, Vol. XVII. Part 4. 8vo. 1896.
Birmingham Natural History and Philosophical Society — Proceedings, Vol. IX.

Part 2. 8vo. 1895.
British Architects, Royal Institute of — Journal, 3rd Series, Vol. III. No. 12. 4to.

1896.
British Astronomical Association — Memoirs, Vol. IV. Part 3. 8vo. 1896.

Journal, Vol. VI. No. 6. 8vo. 1896.
Camera Club — Journal for April, 1896. 8vo.
Chemical Society — Journal for April, 1896. 8vo.

Proceedings, No. 163. 8vo. 1895-96.
Cracovie, Academic des Sciences — Bulletin, 1896, Nos. 2, 3. 8vo.
Dax, Socide de Borda—20'' Annee (1895), 3-^ Trimestre. 8vo. 1895.
East India Association — Journal for April, 1896. 8vo.
Editors — American Journal of Science for April, 1896. 8vo.

Analyst for April, 1896. 8vo.

Anthony's Photographic Bulletin for April, 1896. 8vo.

Athenaeum for April, 1896. 4to.

Bimetallist for April, 1896.

Brewers' Journal for April, 1896. 8vo.

Chemical News for April, 1896. 4to.

Chemist and Druggist for April, 1896. 8vo.

Electrical Engineer for April, 1896. fol.

Electrical Engineering for April, 1896. 8vo.

Electrical Review for April, 1896. 8vo.

Electric Plant for April, 1896. 4to.

Electricity for April, 1896. 8vo.

Engineer for April, 1896. fol.

Engineering for April, 1896. fol.

Engineering Review for April, 1896. 8vo.

Homoeopathic Review for April, 1896. 8vo.

Horological Journal for April, 1896. 8vo.

Industries and Iron for April, 1896. fol.

Invention for April, 1896.

Ironmongery for April, 1896. 4to.

Law Journal for April, 1896. 8vo.

Lightning for April, 1896. 8vo.

London Technical Education Gazette for April, 1896. 8vo.

Machinery Market for April, 1896. 8vo.

Monist for April, 1896. 8vo.

Nature for April, 1896. 4to.

Nuovo Cimento for Feb. 1896. 8vo.

Photographic News for April, 1896. 8vo.

Science Siftings for April, 1896.

Scientific African for April, 1896. 8vo.

1896.] General Monthly Meeting, 189

Scots Magazine for April, 1896. 8vo.
Technical World for April, 1896. 8vo.
Terrestrial Magnetism for April, 1896. 8vo.
Transport for April, 1896. fol.
Tropical Agriculturist for April, 1896.
Work for April, 1896. 8vo.
Zoophilist for April, 1896. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXV. No. 121. 8vo. 1896.
Field Columhian Museum, Chicago — ^Archseological Studies from the Ancient

Cities of Mexico. By W. H. Holmes. Part 1. 8vo. 1895.
Florence, BiUioteca Nazionale Centrale—'Bollei'mo, No. 247. 8vo. 1896.
FranJdin Institute — Journal for April, 1896. 8vo.

Geographical Society, Royal — Geo(;;raphical Journal for April, 1896. 8vo.
Holmes, Basil, Esq.—l^ife of Sir David Baird. 2 vols. 8vo. 1832.

Sketch of the Civil Engineering of North America. By D. Stevenson. 8vo,
1838.
Holmes, Basil, Esq. — An Epitome of the Elementary Principles of Natural and
Experimental Philosophy, together with an Account of the Steam Engine.
(Lectures delivered at the Eoyal Institution.) By J. Millington. 8vo.
1823.
A Manual of Botany. By R. Bentley. 8vo. 1861.
Imperial Institute — Imperial Institute Journal for April, 1896.
Johns Hopldns University — University Studies, Fourteenth Series, No. 8. 8vo.
1896.
American Chemical Journal, Vol. XVIII. No. 4. 8vo. 1896.
American Journal of Philology, Vol. XVI. No. 4. 8vo. 1895.
Linnean Society — Proceedings, Nov. 1894 to June, 1895. 8vo. 1896.
Madras Literary Society — Madras Journal of Literature and Science for 1889-94.

8vo. 1894,
Manchester Geological Society — Transactions, Vol. XXIV. Parts 5-7. 8vo. 1896.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Vol. X.

No. 2. 8vo. 1896.
Mexico, Sociedad Cientifica '^Antonio Alzate" — Memorias y Revista, Tome IX.

Nos. 1-6. 8vo. 1895-96.
New York Academy of Sciences — Annals, Vol. VIII. Nos. 6-12. 8vo. 1895.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLV. Part 3. 8vo. 1896.
Odontological Society of Great Britain — Transactions, Vol. XXVIII. No. 5. 8vo.

1896.
Paris, Societe Franmise de Physique — Bulletin, No. 77. 8vo. 1896.
Pharmaceutical Society of Great Britain — Journal for April, 1896. 8vo.
Philadelphia Academy of Natural Sciences — Proceedings, 1895, Part 3. Svo. 1896.
Physical Society of London — Proceedings, Vol. XIV. Part 4. Svo. 1896.
Queen's College, Gahcay — Calendar for 1895-96. 8vo.
Quekett Microscopical C?u&— Journal, Nos. 36-38. 1895-96.
Badcliffe Library, Oxford — Catalogue of Books added to the Radcliife Library

Oxford University Museum, during the year 1895. 8vo. 1896.
Rochechouart, Societe des Amis des Sciences et Arts — Bulletin, Tome V. Nos. 3, 4.

8vo. 1895.
Rome, Ministry of Public Works — Giornale del Genio Civile, 1896, Fasc. 1. And

Desigui. fol.
Royal Society of London — Philosophical Transactions, Vol. CLXXXVI. B.

No. 134. 4to. 1896.
Saxon Society of Sciences, Royal —
Philologisch-Historische Classe —

Abhandlungen, Band XVII. Nos. 2, 3. 8vo. 1896.
Selhorne Society — Nature Notes for April, 1896. 8vo.

Sidgreaves, The Rev. W. S.J. F.R.A.S. (the Autlior) — Results of Meteorological,
Magnetical and Solar Observations for 1896. 8vo. 1896.

190 Oeneral Monthly Meeting. [May 4,

Smithsonian Institution — The Composition of Expired Air and its effects upon

Animal Life. By J. S. Billings, S. Weir Mitcliell and D. H. Bergey. 4to.

1895. (Smith Cont. to Knowledge, 989.)
Society of Arts — Journal for April, 1896. 8vo.
TaccMni, Professor F. Hon. Mem. R.L (the ^M^Tior)— Memorie della Society degli

Spettroscopisti Italiani, Vol. XXV. Disp. 3^ 4to. 1896.
Toulouse, Societe Archeologique du midi de la France — Bulletin, No. 16. 8vo.

1895.
United Service Institution, Royal — Journal, No. 218. 8vo. 1896.
United States Department of Agriculture — Monthly Weather Review for Oct.

1895. 8vo.
Uiiited States Department of Interior — Report on Crime, Pauperism and Benevo-
lence in the United States at the Eleventh Census, 1890, Part 2. 4to. 1895.
Report on Wealth, Debt and Taxation at the Eleventh Census, 1890, Part 2.

4to. 1895.
United States Patent O^ce— Official Gazette, Vol. LXXIV. Nos. 2-9. 8vo. 1896.
Upsal, V Ohservatoire Mdt^orologique — Bulletin Mensuel, Vol. XXVII. 8vo.

1895-96.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1896,

Heft 8. 4to. 1896.
Victoria Institute— Journal of the Transactions, Vol. XXVIII. No. 110. 8vo.

1896.
Vienna, Imperial Geological Institute — Verhandlungen, 1896, Nos. 1-3. 8vo.
Zoological Society of London — Proceedings, 1895, Part 4. 8vo. 1896.
Transactions, Vol. XIV. Part 1. 4to. 1896.

1896.] Electric Shadows and Luminescence. 191

WEEKLY EVENING MEETING,
Friday, May 8, 1896.

LuDWiG MoND, Esq. Ph.D. F.K.S. F.C.S. Manager and
Vice-President, in the Chair.

Professor Silvanus P. Thompson, D.Sc. F.R.S. M.B.I.
Electric Shadows and Luminescence.

The early days of the year 1896 were marked by the announcement
telegraphed from Vienna to the effect that Professor Roentgen, a
man whose name though little known outside the world of science
was well known and highly esteemed by those who were initiates in
physics, had discovered the existence of rays of a new and extra-
ordinary kind. Taking a Crookes tube, excited of coui'se by a
proper electric spark, and covering it up within a case of black
cardboard, he found it to produce in the surrounding space some
entirely unexpected effects. Black cardboard is impervious not only
to ordinary light and to radiant heat, but also to all those other
known kinds of invisible light beyond the violet end of tlie spectrum,
known as actinic waves, which are such active agents in the produc-
tion both of fluorescence and of photographic actions. Yet the
invisible emanations of the Crookes tube, which passed freely
through the opaque cardboard, were found by Roentgen to be capable
of revealing their presence in two ways. In the first place he had
seen them to project shadows upon a luminescent screen of paper
coated with the highly fluorescent substance called platino-cyanide
of barium, and in the second place he had been able to photograph
these shadows by letting them fall upon an ordinary photographic
plate. The discovery was singular. It revealed the existence of a
remarkable and hitherto unexpected species of radiation. It added
another to the many puzzling phenomena attendant upon the dis-
charge of electricity in vacuo. It proved that something which in the
ordinary sense in which those terms are used is neither light nor
electricity was generated in the Crookes tube, and passed from it
through substances opaque alike to both.

But that which took the imagination of the multitude by storm,
and aroused an interest the intensity the like of which has not been
known to be aroused by any other scientific discovery in our times,
was not the fact that Professor Roentgen had seen luminescent
shadows from a Crookes tube, or had obtained a photograph of those

192 Professor Silvanus P. Thompson [May 8,

shadows ; it was the entirely subsidiary and comparatively unim-
portant point that to these mysterious radiations flesh is more
transparent than bone.

Let me begin by showing you as a first experiment that same fact
which Eoeutgen announced of the production of luminescent shadows
by these invisible rays. Before you there stands a Crookes tube,
of the most modern kind,* for this particular purpose. We have
here an induction coil t capable of giving 6 -inch sparks, with which
we can send electric discharges through the tube, illuminating it with
its characteristic golden-green glow. I now cover over the tube and
exclude all ordinary light, not with a box of black cardboard but
with a black velvet cloth. And now in the darkness I am able
to show you on a sheet of paper covered with the highly fluor-
escent platino-cyanide of barium — the well known substance which
Eoentgen himself was using — the shadows of objects placed behind.
See how this sheet shines in the light of the tube transmuting the
invisible radiations into visible light. I hold my purse behind the
screen — you see the shadow of the metal clasp, and of the metal
contents (two coins and a ring), but you see not the shadow of the
leather purse itself, for leather is transparent to these rays while metal
is opaque. I hold my hand behind and you see — or at least those of
you who are within a few yards of me — the shadow of my hand, or
rather of the bones of my hand, surrounded by a fainter shadow of
the almost transparent flesh.

Now the second fact that Eoentgen announced was that these
same rays which escape through the opaque covering and excite
fluorescence are also caj^able of taking photographic impressions of
the shadow^s. There is nothing w^hatever new about this part of the
subject : it is the old pliotograj)hy ; there is no " new photograi)hy."
Here is a common camera back, and here inside it is a photographic
dry-plate — quite a common dry-j^late, such as has been known for ten
years. This plate is covered with a black card, so that it may not
become fogged by the light of the room when I draw the slide. All I
have to do is to lay it upon the table below the Crookes tube so as to
cast the shadow upon it, and after due exposure develop the plate
in the ordinary well-understood way. Now it may be interesting
to see the proof of the fact that bone is less transparent than flesh.
So, with your permission, I will ask my little daughter to have her
hand photographed. (Experiment made.)

At the time of Eoentgen's announcement, the exposure required
with the Crookes tubes that were then in existence was from twenty
minutes to, I think, two or three hours. Very shortly improvements
were made ; and with these modern tubes one minute is quite suffi-

* A Crookes " focus " tube (Jackson pattern), constructed by Messrs. New-
ton & Co., of Fleet Street, London.

t An Apps coil capable of giving sparks 25 centimetres in length, but on
this occasion excited v?ith only 5 cells, giving sparks about 6 inches iu length.

1896.] on Electric Shadows and Luminescence. 193

cient for an exposure. Indeed one minute is too much for many
objects. I have not previously tried this particular tube, though I
judge by its appearance that it is in good condition. As soon as
the exposure of one minute is over we will have the plate taken into
the dark room and developed in the ordinary way ; and when it is
developed we will have it brought back into this room and put into
the lantern, that you may see what has been done.

Now, while we are taking photographs, I may as well take a
second to illustrate another point. Roentgen investigated in the
most careful and elaborate way the relative transparency of different
materials for these mysterious rays. He noticed that wood, and
many substances which are opaque to ordinary light, are transparent
to these rays ; whilst, on the contrary, several substances that are
transparent to light, such as calc-spar and heavy glass, are very
opaque toward them. Many experimenters have examined this
question of relative transparency. I devoted a day or two to the
study of gems, and found that imitation rubies made of red glass are
much more opaque than real rubies, and that paste diamonds are
much more opaque than real diamonds. Real diamonds and rubies
are indeed very transparent, and scarcely cast any shadows on the
luminescent screen, though I have found diamond to be more opaque
than an equal thickness of black carbon. There are laid upon this
piece of card two rubies, one being only a glass ruby. There is~al«o
a row of four small diamonds. I will leave you to find out whether
they are false or real. And then there are three larger diamonds,
one of which is uncut and is a genuine South African stone. I lay
them down upon a photographic plate and expose them to the
Roentgen rays so that we may test their relative transparency.
(The two photographs thus taken were projected upon the screen at
the close of the lecture.)

Amongst the things which Roentgen told us was the fact that
different kinds of glass are unequally transparent : that lead-glass,
for instance, is much more opaque than soda-glass, or potash-glass, or,
indeed, any glass which does not contain a heavy metal like lead.
He found that practically the transparency was governed by the
density; that the heavy or the dense substances were the more
opaque. There is now some reason to correct that statement, though
in the main as a first approximation it is perfectly true. Professor
Dewar has shown that you must take into account, not the density in
gross but the atomic weight. Taking any homologous series, for
example, such as a number of sulphides, or oxides, or chlorides, that
one which contains the atomically heavier metal will be the more
opaque. Again, the bromide of sodium is more opaque than the
chloride of the same metal, and the iodide is more opaque than the
bromide. But as the correspondence between relative opacity and
molecular or atomic weight breaks down when we try to pass from
one series of compounds to a different series, there is some reason to
carry the matter to a further degree of approximation. We must go

Vol. XV. (No. 90.) o

194 Professor Silvanus P. Thompson [May 8,

beyond the suggestion of atomic weight. The nearest approach to a
law that 1 have been able to get at yet, on comparing tables of statistics,
is that the transparency is proportional to the specific heat. For
homologous series this is, of course, the same as saying that the
transparency is inversely proportional to the molecular weight.

Eoentgen found all the heavy metals to be remarkably opaque,
while light metals like sodium and aluminium, and even zinc, are
remarkable for their transparency. Aluminium, which is opaque to
every known kind of light, is transparent, even in sheets halt an inch
thick, to these rays. Lithium, the lightest of solid metals, and with
an atomic weight 7 as against aluminium 27, is so transparent that I
have not been able yet even to see its shadow. Of all liquids water
is the most transparent, and it has the highest specific heat of all of
them.

Roentgen further found these rays to be incapable either of refrac-
tion by lens or prism,* or of reflection by any polished mirror.
Eeflection there is in one sense, that of ditifuse reflection, such as
white paper exercises on common light. No lens can concentrate
these rays : they are also apparently incapable of being polarised.
One difficulty in experimenting on these strange properties is that air
itself acts as a turbid medium, reflecting back diffusely, as a smoky
cloud would do for ordinary light, a portion of the rays.

Finding that these radiations differed in so many ways from
ordinary light, and while resembling and even surpassing ultra-violet
rays in their strong actinic properties, yet differed entirely from them
in respect of the properties of refraction, reflection and polarisation, he
named them " X-rays." To judge by his own writing, he appeared to
wish that they might prove to be longitudinal vibrations in the ether,
the possibility of the existence of which has been a subject of specu-
lation on the part of some of the most learned of mathematical
physicists. Others have suggested that these X-rays are transverse
vibrations of a much higher frequency and shorter wave length than
any known kind of ultra-violet light. Others again see in them
evidence that radiant matter (i.e. kathodic streams of particles) can
traverse the glass of a Crookes tube, and regard them as material in
their nature. Lastly, it has been suggested that they may be neither
waves nor streams of matter, but vortex motions in the ether.

To follow out the bearings of these speculations, as well as to
trace the development of discovery, let us go back a little and consider
what was the starting point of Roentgen's research. He was using a
Crookes tube. It is one of the difficulties of my task to-night that
I have to speak in the presence of him who is the master of us all in

* Perrin in Paris, and Winkelmann in Jena, have independently found what
they believe to be evidence of refraction through an aluminium prism. Both
observers detected a slight deviation, but in a direction toward the refracting
angle, showing aluminium to have for these rays a refractive index slightly less,
with respect to air, than unity.

1896.] on Electric Shadows and Luminescence. 195

tliis subject of electric discharges in the vacuum tube. But to under-
stand the discoveries of Crookes let us first witness a few experimental
illustrations of the phenomena of electric discharges in vacuum tubes.
Many of them have been known for half a century. We all know of
the researches made in England by Gassiot, and by Varley and others,
and the tubes of Geissler of Bonn are a household word. But there
is one set of researches which deserves to be known far better than it
is, that made by Dr. W. H. Th. Meyer, of Frankfort, whose pamphlet *
I hold in my hand. In it he depicts a number of tubes in various
stages of exhaustion, including one in that highest stage of exhaustion
which one is j^rone to think of modern origin.

In order to illustrate the successive phenomena which are pro-
duced when electric discharges are sent through a tube during
progressively increasing exhaustion, there is here exhibited a set of
identical tubes. Each is a simple straight tube, having sealed in
at each end an electrode terminating in a short piece of aluminium
wire. The electrode by which the electric current enters is known
as the anode, that by which it leaves the tube as the kathode. Tlie
only ditference between these eight tubes lies in the degree of rare-
faction of the interior air. The first one contains air at the ordinary
pressure. As its electrodes are about 12 inches apart I am unable
with the Apps induction coil (excited to throw an 8 -inch spark) to
send a spark through it. From the second tube about four-tifths of
the air has been abstracted, and here we obtain a forked brush-like
spark between the electrodes. The third tube has been exhausted to
about one-twentieth part, and shows as the discharge a single thin red
linear spark like a flexible luminous thread. When, as in the fourth
tube, the exhaustion is carried so far as to leave but one-fortieth, the
red line is found to have widened out into a luminous band which
extends from pole to j)ole, while a violet mantle makes its appearance
at each end and spreads over both of the electrodes. On carrying
the exhaustion to the stage shown by the fifth tube, where only about
gi^ of the original air is left behind, we note that the luminous
column has broken ujd transversely into flickering strise, that the violet
mantle round the kathode has become more distinct, and is separated
by a dark interval from the luminous red column, while a second and
very narrow dark space appears to separate the violet mantle from
the surface of the kathode. In the sixth tube the exhaustion has been
carried to about xo^oo- "^^^ flickering strise have changed shape and
colour, being paler. The light at the anode has dwindled to a small
bright patch. The violet glow surrounding the kathode has expanded
to till the whole of that end of the tube ; the dark space has become
more distinct, and within it the kathode now shows on its surface an
inner mantle of dull red light. There is a slight tendency for the

* Beobachtuntjen iiber das gescliichtete electrische Licht, sowie iiber den
merkwiirdigeu Eintinss dcs Magueten auf dasselbe ; von Dr. W. H. Theodor
Mever. Berlin, 1^5^.

o 2

196 Professor Silvanus P. Thompson [May 8,

glass to show a greenish fluorescence near the kathode end. In the
seventh tube the luminous column has subsided into a few greyish-
white nebulous patches, the dark space round the kathode has greatly
expanded, and the glass of the tube has now begun to show a yellow-
green fluorescence. The exhaustion has been pushed so that only about
^TTWU ^^ ^^^^ ^^ *^® original air is present. In the eighth and last
tube only one or two millionths of the original air have been left,
with the result that the tube now oflfers an enormously increased
resistance to the passage of the discharge. All the internal flickering
nebulosities have vanished ; the tube looks as though there were no
residual air within. But now the glass itself shines with a fine
yellow-green fluorescence which is particularly bright in the region
around the kathode. Were the exhaustion to be carried much further
the spark from this induction coil would no longer pass, so high
would the resistance become. All these successive stages up to the
last can be shown in one and the same tube attached to a modern
rapid air pump. But for the proper production of the high vacua of
the last stages, where electric shadows are alone produced, nothing
short of a mercurial pump, either in the form invented by Sprengel
or in that used by Geiesler (or one of the recent modifications) will
suffice.

The phenomenon of fluorescence of the glass, which manifests
itself when the exhaustion has become sufficiently high, was known
in a general way as far back as 1869 or 1870. The tube next to be
shown is a modern reproduction of a tube used at that time by
Hittorf, of Miinster. It dififers from the tubes last shown by having
a bend in it. Hittorf observed that when such a tube is ex-
hausted sufficiently highly to give at the kathode the characteristic
greenish-yellow fluorescence, this greenish-yellow fluorescence re-
fused to go round the bend. It might appear at one end or the other,
according to the direction in which the discharge was being sent, but
would not go round the bend. The efl'ect was as if the discharge
went in straight lines from the bit of wire that served as kathode to
the walls of the tube. Indeed shadow effects were observed by him,
and by Wright, of Yale, and afterwards independently by Crookes,
who greatly extended our knowledge of the facts. We may take this
fact, that the fluorescence caused by the kathode will not go round a
corner, as the starting point of the memorable researches of Crookes
on radiant matter a score of years ago.

Before you are several tubes which illustrate the researches made
by Crookes. The first is a simple glass bulb into which are sealed
the two electrodes — the anode, by which the current enters, ter-
minating in a bit of stout aluminium wire ; the other, by which
the current leaves, called the kathode, terminating in a small flat
aluminium disk. The glass bulb was itself highly exhausted — how
highly we shall presently see. From the flat front surface of the
kathode, when sparks are sent through the bulb, a sort of back-
discharge takes place in a direction normal to the surface. This

1896.] on Electric Shadows and Luminescence. 197

discbarge, which only occurs at a very high degree of exhaustion,
possesses several properties which distinguish it from all other kinds
of discharge. It is propagated in straight lines, causes a brilliant
luminescence wherever it strikes against the glass walls of the
tubes, casting shadows of intervening objects, it heats the surface
on which it impinges, and strikes them with a distinct mechanical
force. Singular to relate, it is also capable of being deflected
by a magnet as though it were a flexible conductor carrying
the current. Struck by the singularity of these kathode rays or
kathode discharges, which formed the subject of several beautiful
researches, Crookes advanced the hypothesis that they consisted of
flights of negatively electrified particles or "radiant matter." The
particles he sometimes spoke of as molecules, sometimes as dis-
sociated atoms, or, as we should now say, ions. He studied the wan-
derings of these flying particles by inserting within the bulb at
different points auxiliary electrodes. He found the interior of the
bulb to be positively electrified in all parts except within the dark
space which surrounds the kathode, that is to say, except within the
range of the actual kathode discharge. The kathode discharge itself
was found to be possessed, to an extent exceeding any other known
agency, of the power of exciting fluorescence and phosphorescence in
minerals and gems. The kathode rays were themselves discernible as
they crossed the interior of the tube. In such a bulb the kathode rays
would form a blue streak impinging straight upon the anode. The.
kathode used in the next Crookes tube, is of a concave shape.
Crookes found that, since the kathode rays left the surface normally,
the result of curving the kathode was to focus the rays toward the
centre of curvature. By so focussing the rays upon a bit of platinum
foil, it was found possible to fuse and even melt the metal.

Unlike the discharges obtained at lower stages of rarefaction, the
direction of these kathode rays was found to be independent of the
position of the anode. He found kathode rays to be produced even
when no internal electrodes were inserted, and when, instead, external
patches of tinfoil were attached to the glass. Their mechanical action
he studied by causing them to impinge upon the vanes of a pivoted
fly which w^as thereby set into rotation. In a later experiment he
caused the fly of a " molecule mill " to be set into rotation, not by the
impact of the kathodic discharge but by the kinetic energy of tlie
particles returning back toward the anode after they had impinged
against the walls of the tube and lost their negative electric charges.
A mere resume of Crookes's work in those years beginning about
1869 or 1870, and extending not only for ten years^ctively, but going
on at intervals until a year or two ago, would of itself fill a whole
course of lectures. Into the controversy which has arisen between
Crookes and the English physicists on the one hand and the German
physicists on the other, there is no need to enter. Suffice it to say
that while the German physicists mostly reject Crookes's hypothesis
of radiant matter, and regard all these various phenomena as the

198

Professor Silvanus P. Thompson

[May 8,

^

result of mere wave motions witliin the tube, tlie Britisli pliysiclsts,
including Lord Kelvin and Sir George Stokes, accept Crookes's view
of the material nature of the kathode rays. Who, indeed, that has
seen the molecule mill at work can doubt that, whether vibrations are
present or not (and doubtless there are vibrations present), there are
actually streams of moving particles as an essential feature of the
kathodic discharge ? For the moment the victory undoubtedly rests
with the views of Crookes.

But of all these phenomena the one which concerns us most is
that of the production of electrical shadows. Erecting in the path
of the kathode rays an obstacle cutout in sheet metal — a cross of thin
aluminium is the favourite object— a shadow of it is observed to be
cast upon the wall of the tube behind it ; the glass phosphorescing
brilliantly except where shielded from the impact of the kathode rays,
so that the shadow comes out dark against a luminous background.
Common soda-glass gives this greenish-golden tint, while lead-glass

exhibits a blue phosphorescence. Not
glass alone, but diamonds, rubies, emer-
alds, calc-spar and other earthy ma-
terials, such as alumina, and notably
yttria, produce the most brilliant effects
under the kathode discharge, some of
them only fluorescing transiently,other8
with a persistent phosphorescence. As
a sample is shown a tube in which
a sea shell, slightly calcined to remove
organic matter, is made to emit a bril-
liant luminescence under the impact of
rays from a kathode jilaced above it.
The shell itself casts a shadow against
the lower part of the tube. Some of the shadow effects are very
mysterious and have recently claimed much of my attention. The
size of the kathodic shadows is affected by the electrical state of
,the object. Electrifying it positively makes its shadow shrink to
smaller dimensions. Electrifying it negatively causes a singular en-
largement of the shadow\ There seems to be no difference between
the shadow of a metallic body and that of a non-metallic body of the
same size. All bodies cast shadows, however thin. Even a film of
glass Toius i^c^ thick — so thin that it showed iridescence like a
soap bubble — was found by Crookes to cast its shadow.

Another point noticed by Crookes was that if the exhaustion is
carried very far, and the tube is stimulated by a sufficiently strong
electromotive force, the phosphorescence may occur at points not in
the line of discharge but round a corner. Not that the kathode
rays turn the corner, however. Aj^parently some of the more quickly
moving or perhaps more highly charged particles — atoms, molecules
or ions — those, in fact, described by Crookes as " loose and erratic "
— would manage to get round the corners and produce effects of a

Fig. 1.

1896.]

on Electric Shadows and Luminescence.

199

more or less directly kafchodfc kind in places where they could not
have penetrated by any motion in a straight line.

Here (Fig. 1) is a tube — a variation on one of Hittorf s, having
two branches that cross one another at right angles. There are two
small disks of aluminium in the bulbous ends to serve as electrodes.
When either of these is made the kathode, the whole limb in which it
is situated fluoresces brilliantly of a golden-green tint, particularly at
the distant end. But the other limb remains dark, save for a little
nebulous blue patch, near the anode, due to residual gas. Another
tube (Fig. 2) is made as a zigzag, and here again only the end
branch shines. On reversing the current the luminescence shifts to
the other end. But when the tube is more highly exhausted, the
phosphorescence is observed not only in the end branch where the
kathode is, but also slightly at the end wall of each branch of the
zigzag. Apparently the residual gas will act partly as its own
kathode, and throw off something which causes the glass beyond to
phosphoresce.

And now let me remark that not one of all the tubes shown since
the first one, is capable of showing a shadow upon the fluorescent

Fig. 2.

screen outside, or of taking a photograph through a sheet of aluminium.
Even the brilliant tube which showed so excellently the shadow of the
cross, fails to show any result after hours of vain waiting. It yields
no rays that will penetrate aluminium. For experiments with
Roentgen rays it is absolutely necessary that the process of exhaustion
should be carried beyond the stage that suffices for the production of
kathode shadows ; it must be pushed to about that limit which Crookes
himself described as his unit for the degree of vacuum, namely, one-
millionth of an atmosphere. I do not say that with long exposures
photographs cannot be taken when the degree of exhaustion is lower.
Something depends, too, upon the degree to which the electric dis-
charge is stimulated, and something also depends upon the shape and
structure of the tube and upon the size and shape of the kathode.
But on none of these things does the emission of X-rays depend so
much as upon the degree of vacuum. The highly exhausted vacuum
is the one real essential.

So soon as Crookes's researches upon electric shadows had become
known, electricians set to work to try to produce electric shadows in
ordinary air without any vacuum. One of the ablest of exjierimenters,

200

Professor Silvanus P. Thompson

[May 8,

Professor W. Hoitz, was successful, using as a source of electric dis-
charge the electrified wind which is given off by a metal point attached
to the pole of an influence machine. If in a perfectly dark room such
a point is placed opposite and at a few inches from a wooden disc
covered with white silk and connected at its back or edges to the
other pole of the machine, it will be observed to show a pale lumi-
nosity over a circular patch where it is struck by the electric wind.
If then the object is brought between the disc and the point a shadow
will be observed to be cast upon the white surface. Non-conductors
do not cast shadows as well as conductors do. A piece of thin mica
scarcely casts a shadow at all until it is moistened. Double shadows
can be got by using two disks covered with silk facing one another :
any conducting object introduced between them casts a shadow on

Dry plate.^^^^

(sss^^SSS

Flate of Coppjtr

Fig. 3.

both. If such a shadow from an electrified point is cast downward
upon a sheet of ebonite or pitch, the parts not shaded are found after-
wards to remain electrified, and can be discovered by scattering over
them Lichtenberg's mixed powders of red lead and lycopodium, thus
perpetuating the shadow.

But now it is possible to produce electric shadows in another way,
photographically, as has been known for some years,* from metal ob-
jects such as coins, by simply laying them down upon a photographic
dry-plate (a gelatino-bromide plate) and sending an electric spark
(from an induction coil) into them.

Fig. 3 shows the arrangement adopted by the Rev. F. J. Smith, who
is kind enough to exhibit in the library to-night some scores of his

Proceedings Physical Society of London,' vol. xi. p, 353, 1892.

1896.]

on Electric Shadows and Luminescence.

201

beautiful " inductoscript " photographs. Upon the screen I throw a
few samples, including a print of one of the jubilee coins (Fig. 4).
These curious photographs are pro-
duced simply by the chemical ac-
tion of the electric discharges
which stream off from all the pro-
jecting portions, and so roughly
reproduce an image of the coin.
Since Roentgen's discovery many
persons have announced their sup-
posed discovery of the production
of electric shadow-pictures without
the aid of a Crookes tube. What
they have really observed is, how-
ever, totally different. They have
not been producing X-rays at all,
but have merely rediscovered these Fig. 4.

inductoscript shadows.

Between the researches of Crookes, however, and those of
Roentgen there came in a very remarkable body of researches in
Germany. I have but to name Goldstein,* Puluj, f Hertz, J

* Goldstein, in his researches on the Keflection of Electric (i.e. Kathode)
Eays in ' Wiedemann's Annalen,' xv. 246, 1882, came very near to the discovery
of the Roentgen rays. After pointing out that Hittorf had held the opinion
that the kathode rays end at the place where they strike upon a solid wall, and
that they are unable to proceed in any direction at all from thence, Goldstein
directs attention to the circumstance that fluorescent patches are sometimes seen
at the end of crooked tubes, where they could not have been caused by the
direct impact of kathode discharges. He discusses the question whether this
is due to reflection or to a deflection caused by the spot where impact first took
place having become electrified negatively, and therefore acting as a secondary
kathode. The latter hypothesis is rendered untenable by his observation that
if the spot of first impact is made an anode the effect still occurs. He then
shows that the phenomena are inconsistent with a specular reflection, but are
explained by supposing that there is a diffuse reflection. He then sums up as
follows : — " A bundle of katliode rays does not end, at least under those circum-
stances under which it excites phosphorescence, at the place where it strikes
upon a solid wall, but from the place of impact on the wall there proceed electric
rays in every direction in the gaseous space. These rays may be considered as
reflected. Any solid wall of any property whatever may serve as a reflecting
surface. It is immaterial whether or not it is capable of phosphorescence, or
whether it consists of an insulator or of a conductor. The reflection is diffuse, no
matter whether the surface is dull or most highly polished. An anode reflects
the kathode rays sensibly as well as a neutral conductor or an insulator. The
reflected rays have, like the direct kathode rays, the property to excite phos-
phorescence at their ends. They are subject to deflection, and their ends are
deviated in the same sense as the ends of kathode rays, which would extend
from the reflecting surface toward the place hit by the reflected rays."

t Puluj, " Radiant Electrode Matter and the so-called Fourth State." Pub-
lished in vol. i. of ' Physical Memoirs,' by the Physical Society of London, 1889.
These are translated from papers published in 1883 in the Memoirs of the Imperial
Academy of Sciences of Vienna.

X H. Hertz. Researches on the Glow-Discharge, Wied. Ann. six. 782, 1883.
Hertz regards the kathode rays as a property of tlie ether, not as consisting ol

202 Professor Silvanus P. Thompson [May 8,

Wiedemann,* and Lenarcl,t amongst the workers, to show what in-
terest has been concentrated on the subject. Hertz, whose loss science
has not ceased to lament, observed that a part at least of the kathode
rays were capable of passing through thin aluminium sheet, a pro-
perty which confirmed him in his previous doubt as to the material
nature of the kathodic discharge. His pupil, Philipp Leuard, now
Professor Lenard, of Aachen, took up the point. He fitted up a
tube with a small window of aluminium foil ojDposite the kathode,

moving particles. He finds the kathode rays to consist of a heterogeneous variety
of kinds which differ from one another in their properties of causing phospho-
rescence, of being absorbed, and of being deflected by the magnet. On the Trans-
mission of the Kathode Kays through Tliin Layers of Metal, xlv. 28, 1892.
Hertz finds that glass fluoresces in kathode rays, even if covered with gold leaf
or thin films of various metals, though not if covered with thin mica. Aluminium
was found best, and allowed fluorescence to occur even when a sheet of aluminium
leaf was used so thick as to be opaque to light. A diaphragm of thin aluminium
leaf on a metal frame placed insi(ie a Crookes tube at 20 cm. from the kathode,
permitted enough rays to pass to give a tolerably bright and even fluorescence
over the whole of the further end of the tube. These rays, after passing through
the leaf of metal, still showed rectilinear propagation (with some diffusion) and
had not lost the property of being deflected by the magnet.

* E. Wiedemann's papers which are of special importance have mostly
appeared in ' Wiedemann's Annaleu.' The following are the chief of them.
Some of the later have been written in collaboration with Prof. H. Ebert.

On the Phosphorescent Light excited by Electric Discharges, Wied. Ann. ix.
157, 1880.

On P^^lectric Discharges in Gases, xx. 756, 1881.

On Fluorescence and Pho^^phorescence, Pt. I. xxxiv. 446, 1888.

On the Mechanism of Luminosity, xxxvii. 177, 1889.

On Kathodo- and Photo-Luminescence of Glasses, xxxviii. 488, 1889.

On Electric Discharges in Gases and Flames, xxxv 209, 220, 234, 237, 255,
1888.

On Electric Discharges, xxxvi. 643, 1889.

On the Apparent Repulsion of Parallel Kathode Pays, xlvi. 158, 1892.

On Electric Discharges; Excitation of Electric Oscillations and the Relation
of Discharge-tubes to the same, xlviii. 549, and xlix. 1, 1893.

Researches on Electrodynamic Screening-Action and Electric Shadows, xlix.
32, 1893.

Luminous Phenomena in Electrode-less rarefied Spaces under the Influence
of rapidly alternating Electric Fields, 1. 1, 221, 1893.

With J. B. Mepserschmitt, on Fluorescence and Phosphorescence, Pt. II.
Validity of Talbot's Law, xxxiv. 463, 1888.

With H. Ebert, on the Transparency of Kathode Deposits, Silzber. d. phys.-
med. Soc. zu Erlangen, Dec. 14, 1891.

t Lenard's papers are : —

Note on a Phosphoroscope, with spaik illumination, Wied. Ann. xxxiv. 918,
1888.

With M. Wolf, Luminescence of Pyrogallic Acid, xxxiv. 918, 1888.

With V. Klatt, on the Phosphorescence of Copper, Bismuth, and Manganese
in the Sulphides of Alkaline Earths, xxxviii. 90, 1889.

On Kathode Rays in Gases at Atmospheric Pressure, and in the most extreme
vacuum, li. 225, 1894.

On the Magnetic Deflexion of the Kathode Rays, lii. 22, 1894.

On the Absorption of the Kathode Rays, Ivi. 255, 1S95.

1896.]

on Electric Shadows and Luminescence.

203

means of vacuum-tight cement.

its form being that shown in Fig. 5. The kathode was a flat disk on
the end of a ghxss-covered wire stem. The anode was a cylindrical
tube of brass surrounding the kathode. Upon the farther end of
the tube a brass cap was fixed by
Over a small orifice in this
brass cap was set the alumin-
ium window of foil only ^i^
millimetre thick. By this
means he was able to do what
had previously been supposed
impossible, bring the kathode
rays out into the open air. Or,
at least, that is what he ap-
pears to have considered that

he was doing. Certainly he succeeded in bringing out from the
vacuum tube rays that, if not actual prolongations of the kathode
rays, were closely identified with them. He examined their proper-
ties both in the open air and in gases contained in a second chamber
beyond the window, and
found them to be capable of
producing photographic im-
pressions on sensitive i)lates.
He further examined the ques-
tion whether they can be de-
flected by a magnet. Fig. 6,
which is copied from Lenard's
paper, shows the results. The
row of spots on the left side
shows the photograj^hic effect
under various different condi-
tions of experiment when there
was no magnet present. The
spots in the right-hand row
show the effects obtained when
a magnet was present. For
example, in the third row from
the top it is seen that the
bundle of rays when subjected
to the influence of the magnet
is partially dispersed, the spot
being enlarged sideways and
having a kind of nebulous tail.
This proves that through the
aluminium window there came
some rays which were deflected by a magnet, and some rays also
which were not deflected by a magnet. The question naturally arises
whether the rays which Lenard had thus succeeded in bringing out
into the open air are the same thing as the rays with which Crookes

Fig. 6.

204

Professor Sihanus P. Thompson

[May 8,

had been working with inside the vacuum. To that question the
final answer cannot yet be given. Certainly some of the Lenard
rays resemble the interior kathode rays : but some differ in the
crucial respect of deflectability by the magnet. The higher the
degree of vacuum, the less are the rays deflected.

Having touched all too briefly upon the researches ot Lenard, it
remains for me to speak of those of Wiedemann, of Erlangen, who for
many years has made a study both of the phenomena of electric
discharge and of those of fluorescence and phosphorescence. In a
research made in the year 1895 he attained some results of singular
interest. He had been making electric discharges, in collaboration
with Professor Ebert, by a special apparatus for producing electric

oscillations of high frequency. This apparatus, in the modified form
given to it by Ebert,* stands on the table before you. It is an
apparatus of the same class as that described here some years ago by
Oliver Lodge, for producing Hertzian waves. An oscillating spark
is produced between two polished balls set between two condensers
A and B, each made of plates of sheet zinc (Fig. 7) a few millimetres
apart. Their external circuit is, however, led into the primary of a
small induction coil, the secondary of which goes to a third condenser
C. When spaiks from the Apps coil are sent to the spark-gap, the
oscillations of the two primary condensers set up secondary oscilla-

' Wiedemann's Annalen,' hii. p. 144, 1894.

1896.] on Electric Shadoivs and Luminescence, 205

tions in the third condenser, to which a vacuum tube can be connected.
If, now, by adjusting the distances between the plates of condensers
we tune the primary and secondary circuits together, the electric
oscillations that result will persist much longer than if the circuits
are not so tuned. Though each oscillation may last less than the
1 00-millionth of a second, there will be at each spark some 20,000 or
30,000 oscillations before they have died out. Wiedemann and
Ebert have found that these persistent oscillations are specially
adapted to excite luminescence. To illustrate the point I select here
an old Geissler tube with a comparatively poor vacuum. When
stimulated by ordinary sparks directly from the Apps coil through
the platinum electrodes at its ends, it shows the usual features of
Geissler tubes : there is a luminous column extending through the
central bulb with stratifications along its length, while around the
kathode is the usual violet glow. The glass shows no fluorescence. I
now charge the connections, uniting the wires from Ebert's apparatus,
not to the terminal electrodes of the tube but to two patches of tin-
foil stuck upon the outside of the central bulb. Under these
conditions the electric oscillations illuminate the central bulb with a
glow quite different from that previously seen. Beneath each patch
of foil you can discern the bluish kathode discharge, and the glass
now shines with characteristic apple-green fluorescence. By moving
one plate of one of the condensers in or out I alter the conditions of
resonance in the circuit ; and when the tuning is best the fluorescence
is at its brighest. Now Wiedemann observed * that the light so
generated is capable of exercising a photographic action and of other
etifects, but is incapable either of passing through a thin plate of fluor-
spar or of being deflected by a magnet. These rays difi'ered therefore
both from ultra-violet light and from kathode rays ; hence Wiede-
mann pronounced them to consist of a new species which he named
" Entladungsstrahlen " or discharge-rays. It is again a matter for
research to determine whether Wiedemann's rays are the same as
Lenard's, or as Roentgen's rays. Wiedemann's coadjutor Ebert went
on with the research and produced on this principle a little " lumi-
nescence lamp " having two external rings of foil as electrodes ;
and within the vacuum bulb a small pastile of phosphorescent stuff,
which, when excited by the oscillations of the tuned circuits, glows
with a small bright light. Ebert claims that its efficiency is many
times greater than that of the ordinary glow lamp.

Eeturning now to Roentgen's researches, we will take a glance at
the kind of tube (Fig. 8) w^hich he was employing when he made
his discovery of the X-rays. Its general resemblance ta previous
tubes "f is self-evident. The anode was a piece of aluminium tube
through which passed the glass-covered kathode wire, with a small

=" ' Zeitschrift fiir Elektrochemie,' July 1895, p. 159.

t It is, in fact, identical with the form described by Hertz in 1883, see
' Wiedemann's Annalen,' xix. p. 810.

206 Professor Silvanus P. Thompson [May 8,

flat aluminium plate on its extremity. From this flat plate tlie
kathode rays shot forward against the bulging end of the tube ; and,
without any aluminium window rays which were capable of exciting

fluorescence, found their way
t -J "N through the glass walls. Lenard

I , ^..^-.w..-. ^ had so boxed up his tube with

I J brass cap and metal case, that if

]1| anything in the way of rays

cJJ struggled through the glass walls

I of his tube he might not notice it.

UJS Possibly he never looked for it.

Fig. 8. Tf Roentgen made the fortunate ob-

servation that when his tube was
closely covered with opaque black card it still could cause fluores-
cence on a screea covered with platino-cyanide of barium on which
shadows were cast. From seeing the shadows thus to securing their
imprint permanently on a photographic plate was but a small step,
and the discovery that they could pass freely through a sheet of the
metal aluminium was a natural result of an inquiry as to the trans-
parency of different materials. Aluminium is to these rays much
more transparent than ordinary glass. No lens can focus them, nor
mirror reflect them ; and, unlike the kathode rays within the tube,
they are not deflected by the magnet,

The criterion which we have at present as to whether any rays
from any other source are or are not the same as the X-rays is that
they shall bo able to fulfil the following four-fold test : — They
must be capable of exciting luminescence ; they must be capable of
impressing an image on a photographic i)late ; they must be capable
of passing through aluminium ; and they must be incapable of being
deflected by a magnet. In addition they must — so far as present
evidence goes — be incapable of being either refracted or polarised.
Any rays that will fulfil these tests must for the present be considered
identical with X-rays.

Now it has been suggested that the X-rays are the same as ultra-
violet light. This is certainly not so, for ultra-violet light, as known to
us by the researches of Stokes, Tyndall, Becquerel and Cornu, will
not go through aluminium and is not deflected by a magnet, though it
will excite luminescence and take photographs. Furthermore ultra-
violet light can be refracted and polarised.

It has also been suggested that the X-rays are merely invisible
heat-rajs. But this is certainly untrue also, because although Abney
has succeeded in taking photographs by heat rays, they will not go
through aluminium, are not deflected by the magnet, and instead of
exciting phosphorescence they destroy it, as Goethe found out nearly
a hundred years ago.

Neither are they Hertzian waves of longer period than the heat
waves.

So far as is at present known there is no other way of producing

189 6. J on Electric Shadoivs and Luminescence. 207

the X-rays than tliat of employing tlie liiglily exhausted vacuum tube.
They are not found in the light of ordinary electric sparks in air.
They are not discoverable amongst the rays emitted by ordinary
Geissler tubes with a low exhaustion. They are not found in sun-
light or any artificial light. The arc light, though it yields rays
that will give photographic shadows through a thin pine-wood
board, yields no rays, that will pass through aluminium. The only
other rays that seem to come within reasonable possibility of being
X-rays are the Lenard rays, some of which are probably identical
with Roentgen's ; the Wiedemann rays, which are, so far as yet investi-
gated, entirely similar ; and the Becquerel rays, to which some allusion
will presently be made. It will, however, be convenient here to
present a synoptic table (see p. 208) of the various kinds of rays and
their respective physical properties.

One other physical property of the X-rays has been discovered
since the publication of Eoentgen's research. It was discovered
simultaneously in Cambridge (by Professor J. J. Thomson), in Paris,

in Bologna, and in St. Petersburg, that these X-rays

will cause the diselectrification of an electrified body, no f" ''\

matter whether it is positively or negatively charged.* / Q \
That ultra-violet light can diselectrify bodies that have / ^^^ \
been negatively charged was previously known from the J^^^^^^
researches of Hertz, and of Elster and Geitel. This
fresh discovery that X-rays will also discharge a posi-
tive electrification sets up a new physical test. Let me
show you a simple piece of apparatus which I have found
very convenient for the purpose of demonstrating this
discovery. It is an aluminium-leaf electroscope (Fig. 9)
entirely shielded from all external electrostatic influences
by being enclosed in transparent metallic gauze. It Fig. 9.
is so well shielded that even when the cap is removed
it cannot be charged in the ordinary inductive way, but must be
electrified by direct conduction. The aluminium leaves hang at the
side of a fixed central plate as in Exner's electroscope. The con-
taining vessel is of thin Bohemian glass. On exciting the instru-
ment positively from a rod of rubbed glass, or negatively from a
rod of rubbed celluloid, the leaves diverge. In either case as soon
as the X-rays are caused to shine upon the instrument the leaves fall.

It occurred to me that by the aid of this property of diselectrifica-
tion it might be possible to produce electric shadows without having
resort to any photography. You are aware that if the surface or
any part of the surface of a body is electrified, the fact that it

* It is of great interest to note that this identical property had been observed
by Lenard a year previously as an effect of his rays. He found they would dis-
charge an electroscope enclosed in a metal chamber, with an aluminium sheet in
front, whether positively or negatively charged, and at a distance of 30 centi-
metres from his tube.

208

Professor Silvanus P. Thomjpson

[May 8,

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is electrified can be ascertained by dusting over it mixed powders
of red lead and sulphur (or red lead and lycopodium). With the
aid of Mr. Miles Walker, who has worked with me all through this
matter, I have succeeded in producing, on this plan, well-defined
shadows which will now be demonstrated to you. A clean sheet of
ebonite freed from all traces of previous electrification by being
passed through a spirit flame is laid on a properly prepared metal
table. On it stands a small tray of thin aluminium supported on
four insulating legs. In this tray is placed the object whose shadow
is to be cast, for example a pair of scissors or an object cut out
in sheet lead. Over this again is placed a leaden cover with an
opening above the tray : the leaden cover being designed to cut
oif electrostatic influences which might interfere. The tray is
then electrified by a small influence machine, and while it is so
electrified X-rays are sent downwards from a Crookes tube placed
above. They pass down through the aluminium tray and carry
its electrification to the ebonite sheet, which therefore becomes
electrified all over except in the parts which are shielded by the
scissors or other metallic object. The sheet of ebonite is then re-
moved from the leaden enclosure, the aluminium tray lifted off,
and the mixed powders are dusted over, adhering to the surface of
the ebonite and revealing the otherwise invisible electric shadow.
Fig. 10 is a shadow taken in this way. It is but right to mention
that Professor Eighi, of Bologna, has independently obtained electric
dust shadows in a very similar way since these experiments of mine
were begun.

This will be a convenient place to mention a new effect of X-rays
which I have recently observed and which is set down in the table.
When X-rays fall upon a metal object electrified by an influence
machine, they produce some curious changes in the nature of the
discharge into the air. If the body is already discharging itself from
some edge or corner in an aigrette or brush discharge (visible in
darkness only) the size and form of the aigrette is much altered.
Under some circumstances not yet investigated, the incidence of
X-rays causes the aigrette to disappear; under others the X-rays
provoke its appearance.

Since the publication of Roentgen's research the most notable
advance that has been made has been in the direction of improving
the tubes. Eoentgen himself has mostly employed a pear-shaped tube
with a flat circular kathode near the top, producing a beautiful fluor-
escence of the lower part of the tube. He carefully verified the
circumstance that the X-rays originate at that portion of the glass
surface which receives the impact of the kathodic discharge. They
appear in fact to be generated at the place where the kathode
discharge first impinges upon the surface of any solid body. It is
not necessary that the substance which is to act as emitter of the
X-rays should become fluorescent. On the contrary, it appears that
the best radiators are substances that do not fluoresce, namely the

Vol. XV. (No. 90.) p

210 Professor Silvanus P. Thompson [May 8,

metals. I have found zinc, magnesium, aluminium, copper, iron and
platinum to answer — tlie last two best.* Mr. Porter, of University
College, and Mr. Jackson, of King's College, have independently found
out the merits of platinum foil, the former using an old Crookes tube
designed for showing the heating effect of the kathode discharge when

Fig. 10.

concentrated by a concave kathode. On the table are some of the
experimental forms | of tubes I have used. The best results are
found when the kathodic discharge is directed against an interior

* [The author has since found metallic uranium to surpass all other metals.]
t See 'Philosophical Magazine,' August 1896, p. 1(32.

1896.]

on Electric Shadows and Luminescence.

211

piece of metal — preferably platinum — wliich I term the antikatliode *
set obliquely opposite the kathode, and whicli serves as a radiating
surface from which the X-rays are emitted in all directions. When
experimenting with various forms of tube, I have spent much time in
watching, by aid of a fluorescent screen, their emissive activity during
the progress of exhaustion. As already mentioned. X-rays are not
emitted until the stage of minimum internal resistance has been
passed. As the exhaustion advances, while resistance rises and spark
length increases, there is noticed by aid of the screen a luminosity in
the bulb, which, faint at first, seems to come both from the front face
of the bit of platinum that serves as antikathode, and from the back
face ; an oblique dark line (Fig. 11), corresponding to the plane of

Fig. 11.

Fig. 12.

the antikathode, being observed in the screen to separate the two
luminous regions. On slightly increasing the exhaustion the emis-
sion of X-rays from the back of the antikathode ceases while that
from the front greatly increases (Fig. 12), and is quite bright right
up to the angle delimited by the plane of the antikathode. There is
something mysterious, needing careful investigation, in this lateral
emission of X-rays under the impact of the kathode discharge.

Of all the many forms of tube yet produced none has been found
to surpass the particular pattern devised by Mr. Sydney Jackson

* Comptos Rendus, cxxii. p. 807.

P 2

212

Professor Silvanus P. Thompson

[May 8,

(Fig. 13), and known as the " focus tube." It was with such a tube
that I showed you at the outset the fundamental experiments of
Eoentgen. A concave polished kathode of aluminium concentrates
the kathodic discharge upon a small oblique sheet of platinum, which,
while acting as antikathode, serves at the same time as anode. Not
only does the concentration of the kathodic discharge upon the metal
cause it to emit X-rays much more vigorously, but it also has the
effect of causing them to be emitted from a comparatively small and
definite source, with the result that the shadows cast by opaque objects
are darker. [Photographs were then thrown upon the screen, those
taken with " focus " tubes showing remarkable definition of detail.
Some of these were by Mr. J. W. Giffen ; others, showing diseased
bones, &c., taken by the lecturer, and some by Mr. Campbell-Swinton
and by Mr. Sydney Rowland, were also projected.]

The objection has been taken that in these shadow photographs it
is impossible to distinguish the parts that are behind from those that

/

II

Fig. 13.

are in front. In a sense that is so. But I venture to say that the
objection not only can be got over but has been got over. I cannot
show the proof of my assertion upon the screen, because I cannot put
upon the screen a stereoscopic view. But here in my hand is the
Roentgen stereograph of a dead tame rabbit. Two views were taken,
in which the X-rays were thrown in two different directions at an
angle to one another. When these two views are stereoscopically
combined, you observe the rabbit's body with the lungs and liver inside
in their relative positions. The soft organs, which cast faint shadows
almost indistinguishable amid the detail of ribs and other tissues,
now detach themselves into different planes and are recognisable
distinctly. I now send up for projection in the lantern the two
photographs that were taken at the beginning of my discourse, and
which have in the meantime been developed.

Turning back to the phenomena of luminescence,* permit me to

* This very convenient term was suggested some six years ago by Wiede-
mann, to denote the many phenomena known variously as fluorescence or

1896.] on Electric Shadows and Luminescence. 213

draw your attention to the accompanying table of the different kinds
of luminescence with which the physicist has to deal.

TABLE II.

Phenomenon. Substance in which it occurs.

1. Chemi-laminescence Phosphorus oxidising in moist air;

decaying wood ; decaying fish ; glow-
worm ; fire-fly ; marine organisms,
&c.

2. Photo-luminescence :

(a) transient = Fluorescence . . Fluor-spar ; uranium-glass ; quinine ;

scheelite ; platino-cyanides of various
bases ; eosin and many coal-tar pro-
ducts.

(6) persistent = Phosphorescence Bologna - stone ; Canton's phosphorus

and other sulphides of alkaline
earths ; some diamonds, &c.

3. Thermo-luminescence Scheelite ; fluor-spar.

4. Tribo-luminescence Diamonds ; sugar; uranyl nitrate ;

pentadacylparatolylketone.

5. Electro-luminescence :

(a) Effluvio-lumiuescence .. .. Many rarefied gases; many of the

fluorescent and phosphorescent
bodies.

(b) Kathodo-luminescence .. .. Rubies, glass, diamonds, many gems

and minerals.

6. Crystallo-luminescence Arsenious acid.

7. Lyo-luminescence Sub-chlorides of alkali-metals.

8. X-luminescencG Platinocyanides, scheelite, &c.

You will note the names given to discriminate from one another
the various sorts of luminescence. Chemi-luminescence denotes that
due to chemical action, as when phosphorus oxidises, or when the
glow worm emits its cold light. Then there is the photo-lumi-
nescence of the bodies which shine when they are shone upon. There
is the thermo-luminescence of the bodies which shine when heated.
There is tribo-luminescence caused by certain substances when they
are rubbed. There is the kathodo-luminescence of the objects placed

phosphorescence. It refers to all those cases in which light is produced, whether
under the stimulus of electric discharge, of heat, of prior exposure to illumina-
tion, or of chemical action, and the like, in which the light is emitted at a lower
temperature than that which would bu necessary if it were to be emitted by
meaus of incandescence.

214 Professor Silvanus P. Thompson [May 8,

in a Crookes tube. There is the crystallo-luminescence of certain
materials when they become solid; and the lyo-lnminescence of
certain other materials when they are dissolved. Lastly, there is
the X-luminescence set up by the X-rays.

Pausing on photo-luminescence, here is an experiment to illustrate
the difference between its two varieties, phosphorescence and fluor-
escence. Light from an arc lamp, filtered from all rays except
violet and ultra-violet, is thrown upon a disk to which rapid rotation
is given by an electric motor. The disk is painted with two rings,
one of sulphide of calcium, the other of tungstate of calcium. Though
the light falls only on one patch you note that the sulphide shows a
continuous ring of blue light, for the emission of light persists
after the stuff has passed out of the illuminating rays. The tungstate,
on the other hand, shows only a short trail of light, the rest of
the ring being non-luminous, since tungstate has but little persistence.
The light has in fact died out before the stuff has passed a quarter of
an inch from the illuminating beam. This is a sort of phosphoro-
scope designed to show how long different materials will emit light
after they have been shone upon. Those which show only a tem-
porary luminescence are called fluorescent, while those with persis-
tent luminescence are called phosphorescent. For many years it
has been known that some diamonds are phosphorescent. Three such
are here shown,* which, after exposure of one minute to the arc light,
shine in the dark like glow-worms. The most highly phosphorescent
material yet produced is an artificial preparation of sulphide of
calcium manufactured by Mr. Home. The specimen exhibited has a
candle-power of about yL candle per square inch after exposure for
a few seconds to direct sunlight; but the brilliancy rapidly dies
away, though there is a visible luminescence for many days. This
substance is also brightly luminescent in a Crookes tube, and less
brightly under the influence of X-rays.

Many substances, notably fluor-spar, have the property of thermo-
luminescence, that is they shine in the dark when warmed. Powdered
fluor-spar dropj^ed upon a hot shovel emits bright light. If, however,
the spar is heated to a temperature considerably below red heat for
some hours, it apparently comes to an end of its store of luminous
energy and ceases to shine. Such a specimen, even after being kept
for some months, refuses to shine a second time when again heated.
It has, however, long been known that the property of luminescing
when warmed can be restored to the spar by passing a few electric
sparks over it, or by exposing it to the silent discharge or aigrette.
Wiedemann having found that the kathode rays produce a similar
effect, it occurred to me to try to find out whether any of these
X-rays also would revivify thermo-luminescence. I have found
that on exposure for twenty minutes to X-rays, a sample of fluor-spar

* Kindly lent by Dr. J. H. Gladstone, F.R.S.

1896.]

on Electric Shadoivs and Luminescence.

215

which had lost its thermo-luminescent property by prolonged heating
was partially though not completely revivified.

I referred earlier to the rays recently discovered by M. H.
Becquerel. In February last M. Becquerel, and independently I
myself,* made the observation that uranium salts emit some rays
which very closely resemble the X-rays, since they will pass through
aluminium and produce photographic action. It remains to be seen
whether these rays are identical with those of Roentgen.

Finally, let me briefly exhibit two results of my own work.
There is now shown (Fig. 14) the photographic shadow of two
half-hoop ruby rings. One of them is of real rubies, the other of
imitation stones. By artificial light it is difficult to distinguish one
from the other, but when viewed by the
X-rays there is no mistaking the false
for the true. The real rubies are highly
transparent, those of glass are practically
opaque.

After gaining much experience in judg-
ing by photography of the relative trans-
parency of materials, I made a careful
research f to discover whether these rays
can be polarised. At first I used tour-
malines of various thicknesses and colours.
More recently I have tried a number of
other dichroic substances, andalusite, sul-
phate of nickel, of nickel and ammonium,
sulphate of cobalt, and the like. The
method used for all was the following.
A slice of the crystal was broken into
three parts. One part was laid down, and
upon it were superposed the other two in
such a way that in one the crystallographic axis was parallel, in
the other perpendicular, to the crystallographic axis in the first
piece. If there were any polarisation the double thickness where
crossed in structure would be more opaque than the double thick-
ness where the structure was parallel. Not the slightest trace of
polarisation could I observe in any case. Of numerous other ob-
servers who have sought to find polarisation, none has yet produced
a single uncontestable case of polarisation.

At the present moment interest centres around the use of
luminescent screens for observing the Eoentgen shadows, and in this
direction some advances have been claimed of late. It should,
however, not be forgotten that Eoentgen's original discovery was made
with a screen covered with platino-cyanide of barium. Here is a
piece of card covered with patches of several different kinds of lumi-

FiG. 14.

* See ' Philosophical Magazine ' ; July 1896.
t Ih. August 1896.

216 Electric Shadows and Luminescence. [May 8,

nescent stuffs, several platino-cyanirles, several sulphides, and some
samples of tungstate of calcium. Of these materials the brightest
in luminescence is the hydrated platino-cyanide of potassium em-
ployed by Mr. Sydney Jackson ; the next brightest is a French sample
of platino-cyanide of barium; platino-cyanide of strontium coming
third.

Using a focus tube of Mr. Jackson's improved pattern, enclosed
in a box with a cardboard front, and taking a platino-cyanide screen,
I am able in conclusion to demonstrate to all those of my audience
who are within a few feet of the apparatus, the facts that have so
startled the world You can see the bones of my hand and of my
wrist. You can see light between the two bones of my forearm ;
while metal objects, keys, coins, scissors, &c., enclosed in boxes,
embedded in wood blocks, or locked up in leather bags, are plainly
visible to the eye.

Whatever these remarkable rays are, whether they are vortices in
the ether, or longitudinal vibrations, or radiant matter that has
penetrated the tube, or, lastly, whether they consist simply of ultra-
violet light, their discovery affords us one more illustration of the
fact that there is no finality in science. The universe around us
is not only not empty, is not only not dark, but is, on the contrary,
absolutely full and palpitating with light : though there be light
which our eyes may never see, and sounds which our ears may never
hear. But science has not yet pronounced its last word on the
hearing of that which is inaudible and the seeing of that which is
invisible.

[S. P. T.]

1896.] Mr. A. Siemens on Gable Laying on the Amazon Biver. 217

WEEKLY EVENING MEETING,
Friday, May 15, 1896.

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.E.S. Honorary
Secretary and Vice-President, in the Chair.

Alexander Siemens, Esq. M. Inst. C.E. M.B.I.
Cable Laying on the Amazon Biver.

When it had been decided to connect Belem, the capital of the State
of Para, by means of a subfluvial cable with Manaos, the capital of
the State of Amazonas, a preliminary journey became necessary,
during which landing places at the various intermediate stations had
to be selected, some reaches of the river explored, as no reliable
charts exist, and various other details ascertained in order to facilitate
the laying of the cable. This preliminary survey took place in
October of last year during the hottest season, when the river was at
its lowest ; while the cable was laid during January and February of
this year, when the rainy season had commenced and the river was
rising.

The difference in temperature between the two journeys was on
the average not more than about 6J° Cent. (10° Fahr.), but a great
advantage during the laying was the almost continuous presence of
clouds, which mitigated the fierce heat of the sun and kept the tem-
perature at a very pleasant level.

A diagram on the next page shows the curves of the variation in
temperature during the cable-laying expedition, giving the daily
maximum and minimum temperature registered by a thermometer
hung up under the officer's bridge in the open air, but sheltered from
the sun. The third curve represents the temperature of the water,
which was measured by a thermometer on the refrigerating machine,
fixed at a point where the water pumped in from outside first enters
the machine. Besides the date, the places where the observations
were taken are marked on the diagram, and it will at once be noticed
how very equable the temperature was on the main river. The
fluctuations in the air temperature mostly indicate the absence or
presence of clouds, but the water temperature remained perfectly
constant during the whole time spent on the upper reaches of the
river, the proximity of the sea lowering the temperature only to a
small extent.

A glance at the map of South America explains, without much

218

Mr. Alexander Siemens

[May 15,

comment, how immense the volume of water must be which is col-
lected from an area measuring more than 2h million square miles, for
the most part covered with dense forests; and it follows that the

Temperature -Fahrenhei't.

1896.]

on Cable Laying on the Amazon River.

219

temperature of such a body of water cannot be seriously affected by
the daily variations of temperature indicated by the first two curves.
It is extremely difficult to realise the true proportions of this river,
but the comparative table, in which the dimensions of the principal
rivers of the various continents are contrasted with those of the
Amazon, will help to show the importance of this great system of
natural waterways.

Name.

Mississippi . .
La Plata ..
St. Lawrence
Nile .. ..
Volga ..
Danube
Khine ..
Thames
Amazon

Length in
Statute
Miles.

Watershed,
Square
Miles.

Average Discharge,

Cubic Feet per

Second.

Length of

Navigable

Waters in Miles.

2,616>

1,280,3006

675,000

35,000

2,400

994,900«

700,000

20,000

2,200

565,200"

1,000,000'

2,536

3,370

1,293,050«

61,500

3,000^

2,325

592,3006

384,0002

14,600

1,735

320,3006

205,900

1,600^

810

32,600*'

••

550^

210

6,010

2,220*

200=^

2,7305

2,229,900"

2,400,0008

50,000«

Square Miles.

Area of Great Britain and Ireland 120,626

„ British India 1,560,160

„ Brazil 3,219,000

„ Europe 3,790,000

With several other large rivers, the Amazon shares the fate that
its name changes several times during its long course, and that at
various times different affluents have been considered to be the
true source of the main stream. Most geographers, however, regard
the Maraiion as the principal river, a branch of which, called
Tunguragua, rises in Lake Lauricocha, in Peru, in 10° 30' S. lat., and

1 To source of Missouri, 4300 miles. ^ At Saratoff.

^ Exclusive of tributaries. * At Teddington.

^ To sources of Apurimac, 3415 miles.

6 According to Dr. John Murray.

^ According to Darby, the American hydrographer.

* According to Dr. Lauro Sodre.

220 Mr. Alexander Siemens ' [May 15,

76° 10' W. long., although the Ucayale, where it unites with the
Maraiion at Nauta (4° S. lat., 73° W. long.), is quite as important as
the Marafion. If the greatest distance from the mouth is to decide
the question, then the source of the Apurimac, an affluent of the
Ucayale, can lay claim to being the origin of the Amazon, rising in
Peru in 16° S. lat. and 72° W. long

From the Lake Lauricocha the main direction of the Tunguragua
and the Maranon is to the N.N.W., until the river turns eastward,
and shortly after passing Jaen breaks through the Andes, entering
the plains of the Amazon valley by the Falls of Manseriche, a short
distance west of Borja. Its further course is a little north of east,
until it pours its yellow waters into the Atlantic under the equator
between the Cabo do Norte and the Cabo Maguari, which are 158
miles apart. This distance is just about equal to the distance from
Land's End to Cape Clear in Ireland, or from Brighton to Falmouth.
Even west of the island of Caviana, which lies in the mouth of the
river, together with the island of Mexiana and several smaller ones,
the width of the main stream is over 50 miles, equal to the distance
from Portland Bill to the Cap de la Hague. The part of the Amazon
flowing north of the Island of Marajo may therefore be compared in
width to the Channel, but in depth and volume of water it far sur-
passes it. It is a disputed question whether the water flowing south
of Marajo, commonly called the Para river, should be considered as
part of the Amazon or not. A network of natural canals, "the
narrows," connects the two waterways west of Marajo, but the
influence of the tide makes it difficult to decide whether part of the
water of the Amazon finds its way south of Marajo or not. Along
the old course of the Amazon, commencing at the foot of the Andes,
a similar network of islands and canals is formed on both sides of the
river, as the whole country is almost level, and is consequently
inundated during the rainy season for hundreds of miles by the rivers
flowing through it. The most notable exception to this general state
of things occurs at Obidos, where the whole volume of water is com-
pressed into one channel a little over a mile wide, and said to be
about forty fathoms in average depth.

A sounding taken opposite Obidos, about a third of the distance
across the river, showed a depth of 58 fathoms, measured by a steel
wire and Sir William Thomson's sounding machine. As the
current of the river averages three knots in the main channel, it is
not easy to take soundings by an ordinary lead line, and even with
the steel wire an extra heavy weight (33 lbs.) has to be employed, or
the results are not reliable. Besides the wire sounding machine,
James's Submarine Sentinel was used on the preliminary voyage,
wherever serious doubts existed about a channel through which the
cable was to be laid. Usually the sentinel was set at five fathoms,
and when it struck a bar the ship was stopped, and a series of soundings
taken to ascertain the exact depth of water and the extent of the

1896.] on Cable Laying on the Amazon River. 221

shallow place. A further difficulty in sounding originated from the
soft nature of the soil, which for the greater part of the Amazon
valley is alluvial clay, and allows the lead to sink into it for several
feet.

In the narrows there appears, however, a bank of hard clav,
called Tabatinga, which unfortunately blocks nearly all the branches
of the narrows and creates bars all along the course of the Tajipuru,
the main westerly waterway connecting to the Gurupa branch of the
main river. Occasionally the same hard clay forms shallows in the
main river, but as a rule the section of all the channels resembles
the capital letter, U? i«e. the sides are very steep and the bottom
flat. In this respect, as in many others, the Amazon differs entirely
from the Indian rivers, which build up their beds above the sur-
rounding country, occasionally breaking through their natural
banks and seeking a new bed. The Amazon, on the other hand,
carries with it only the light clay sediment which forms the soil
of the whole valley, and the inducement for the main stream to
alter its course is therefore very small, and long straight reaches
are the result.

Under these circumstances the largest vessels can ascend the river
nearly to the foot of the Andes, but the constantly changing sand-
banks at the mouth of the Amazon proper make this approach of the
river dangerous, and the State of Para is for obvious reasons not over
anxious to have the deep channels properly buoyed and surveyed.
This forces all the shipping to enter the Para river, and to pass the
narrows if the Amazon is the goal of the journey. In doing the
latter the choice for large ships lies between one of the channels
(called furos) with a bar, where it joins the Tajipuru, and a furo,
the Macajubim, which has plenty of water, but which winds about in
such a serpentine fashion that only ships with twin screws can pass it
unassisted. These difficulties are, however, much diminished during
the rainy season, when the river rises to such an extent as to drive
all the inhabitants of its banks into the towns, which have been
built wherever a natural eminence secures the inhabitant against the
flood. Near the mouth the difference is naturally not so great as
higher up, where the influence of the tide is felt less; but at
Manaos the difference in level between low river and high river
exceeds 40 feet.

With all rivers carrying sediment, the Amazon shares the pecu-
liarity that its immediate banks are higher than the country lying
behind them, and thus we have in the rainy season the spectacle of
the main river flowing between two banks covered with dense forest,
and immense lakes stretching out on either side of these banks.
These do not entirely dry up during the remainder of the year, so
that the whole of the Amazon valley really forms a huge swamp
covered with a most luxuriant forest which, below Manaos, narrows
to a broad belt close to the main river, with prairies, called campos,

222 Mr. Alexander Siemens [May 15,

at the back of tlie forest stretching out to the hills, where the forest
recommences.

In such a country no land communication of any sort can be
attempted, as the tropical vegetation and the annual inundations of
the rivers destroy everything that man places in the way of the
natural forces. By water, on the other hand, the intercourse between
all habitable parts of the country is easy and expeditious, since
steamers have been introduced in the year 1853. At that time the
journey from Belem to Manaos was shortened from forty days to eight
days, and at present the ocean-going steamers, which do not call at
the intermediate places, accomplish the distance in three days. Belem
lies on a branch of the Para river called Guajara, which unfortunately
does not share the characteristic shape of the Amazon and the furos,
but forms a rather shallow basin in front of the town. The clothing
of a good many inhabitants seems better adapted to a colder climate ;
it is only the airy costume of the ladies, and still more the absence cf
any costume on the children, that betrays the tropical climate. The
harbour of Para is very full cf shipping, and the general build of the
steamers is well adapted to navigate the broad waterway of the main
river, as well as the smaller and shallower affluents, which become
more and more inhabited from year to year. A number of these
steamers, from a small tug, such as accompanied the cable steamer, to
the ocean-going vessels, were photographed from time to time, and
the views taken show at the same time something of the general
features of the landscape.

As the cable steamer could not approach close enough to Pani, the
shore ends were laid with the help of a bargo and a tug, without any-
thing occurring that need be mentioned. By the same means the
sections from Para to Pinheiro and from there to Mosqueiro were
laid, the large steamer laying the section to Soure across the Para
river. Tliese three places are much resorted to by the inhabitants of
Para for their healthy situation, and because they imagine that salt
water reaches at least Soure. The forest encircles all the houses, but
the proximity of the sea, and the breeze blowing regularly every
afternoon, make all these places extremely comfortable. At Soure the
ss. " Faraday " was anchored at a convenient distance from the shore,
so that the shore end might be landed direct from the ship, and as
long as the tide was rising this plan appeared excellent. By the
receding tide, however, a whirlpool was formed with the ship lying
right across the centre, and when it had been turned seventeen times
in one hour the captain was tired of it, and moved the ship to a safer
anchorage.

Another branch of the cable was laid from Para to Cameta on the
River Tocantins, which is 1200 miles long, but unfortunately has
some rapids not far from Cameta, which cut off the navigable upper
portion of the river from direct communication with the general
Amazon system. Cameta boasts of a fine old church and a number

1896.] on Cable Laying on the Amazon Biver. 223

of two-storied buildings, indicating the prosperous state of the
township.

The first station on the main cable is Breves, the centre of the
rubber trade of the islands of the lower Amazon, situate in the
centre of " the narrows." Between Para and Breves is only one
shallow passage, near the lighthouse of Gujabal, and the pilot
managed to run the ship aground there ; luckily it was low tide, and
with the rising tide the ship could be turned. At Breves the ship
was anchored close to the shore, and its stern secured to a tree by a
rope so that the tide could not cause it to swing. Under these
circumstances the landing of the shore ends was an easy matter and
soon finished. The ship then resumed its way into the narrow furos
described above, and night did not put a stop to its progress, as the
outlines of the forest were clearly visible against the sky, and the
water everywhere more than seven fathoms deep. While the speed of
the ship was kept at about six knots, the pilot ordered the quarter-
master to put the helm a-starboard, as he wished to increase the
distance between ship and shore. The quarter-master was, however,
confused, and put the helm hard a-port, with the result that the bows
went into the forest until the branches of the trees touched the fore-
yard. To appreciate the situation it should be mentioned that the
foremast stands 74 feet abaft the bows, and that the foreyard is 69 feet
above the water level. Luckily the soft ground, the elasticity of the
forest trees, and the steepness of the banks, rendered this accident
quite harmless, and on reversing the engines the ship at once came off,
so that the laying could be resumed. Not far from this spot the
Aturia furo branches off, through which the cable had to be laid, but
which was impassable for the ss. " Faraday " on account of a two-
fathom bar at the Tajipuru end of the furo.

As a splice had to be made with some cable on a barge, from which
it was to be paid out through the Aturia furo, the " Faraday " had to
be anchored, and the right-hand shore was approached so as to leave
room for the ship to swing round when the tide turned. At the
critical moment, when the anchor was to be lowered, somebody
blundered, and turned out the electric light, leaving the anchor winch
and its surroundings in darkness. By the time this mistake had been
rectified the ship was dangerously near the shore, and even the
anchor could not sufficiently check its advance, so that it again ran
ashore, stoj)ping within about five feet of a house, much to the alarm of
the inhabitants. This manceuvre fixed the ship in a most convenient
position, so that it was left there until the splice had been finished,
and the tug " Cochrane," with the barge, had started laying the cable
in the Aturia furo. Again there was no difficulty in backing the ship
off the bank, but it had to proceed for twelve miles stern foremost
before the furo was sufficiently wide to allow the ship to turn and go
on to Breves, or rather a few miles beyond, to the mouth of the Boiassu,
in order to enter the Furo Grande and the Tajipuru in a roundabout

224 Mr. Alexander Siemens [May 15,

way. As tlie ship was drawing over twenty-four feet, and the bar at
the end of the Boiassu had only twenty-three feet of water at high
tide, the result was easily foreseen, but the ship remained on the bar
for nine days, by which time sufficient cable had been transferred to
the barge and to the ss. " Malvern " to enable the ship to continue
her journey. During this enforced sojourn in the midst of the most
wonderful combination of islands and rivers, the two naturalists
whom the British Museum authorities had kindly sent with the
expedition, took full advantage of the opportunity to explore the
locality in all directions.*

Unfortunately the time is too short to give many details of the
intermediate stations, but their general aspect is very similar, and
nothing noteworthy occurred at most of them. Commencing at the
mouth of the river, the first station is Chaves and the second Macapa ;
to these two places a branch is laid from Gurupa. The ss. " Faraday "
had the distinction of being the first European steamer which has
navigated the Amazon river below the mouth of the Tajipuru ; in fact
neither the pilots nor the inhabitants knew of any foreign ship that
had ever touched at these ports. In Gurupa, the second station of
the main line, the inhabitants expressed their joy at being put in
communication with the rest of the world, by actively helping in the
landing of the first shore end. A young lady in white, niece of the
mayor, borrowed a handkerchief from one of our engineers, daintily
laid hold of the end of the cable and triumphantly carried it into the
station. Here a ball was started, and the happy couples waltzed round
the cable end to show their appreciation. Meanwhile the tug began
pulling on the barge from which the cable was to be paid out, and just
as these vessels began to feel the current, which runs rather strong
there, something jambed, the cable would not run out, and the tug could
not hold the barge against the current. Barge, tug and cable drifted
down stream, the end gradually disappearing out of the station.
This contretemps luckily did not disturb the dancers, who continued
their rejoicings until the end had been brought back.

Monte Alegre lies on a furo which unfortunately has a shallow
bar at its mouth, so that the cable had to be laid in and out by the
barge and tug. This furo swarmed with " botes," a species of
dolphin much coveted by the naturalists ; but the natives do not try
to catch them because they are neither good for food nor useful in
other ways, besides they are remarkably shy and strong. From
thence the cable is laid to Santarem at the mouth of the Tapajos,
which presents a strong contrast to the Amazon on account of its
clear waters and tranquil flow. This river is 1200 miles long, and is
formed by the union of the Arinos and Juruena, rising in 14° 42' S.
lat., and 60° 43' W. long., in the so-called " aguas vertentes " (the

* 111 th<3 library were exhibited the specimens collected by the naturaHsts
and other members of the expedition.

1896.] on Cable Laying on the Amazon Biver, 225

turning waters) close to the sources of some of the affluents of the
Paraguay river. In the rainy season all these waters mix, and it is
possible to pass in a boat from the mouth of the Rio de la Plata in
35^ S. lat. to the mouth of the Orinoco in 10° N. lat., by way of the
Paraguay, the Tapajos, the Amazon, the Rio Negro and the Cassequiare,
which forms a connecting link between the Amazon system and the
Orinoco.

From Santarem a branch cable is laid to Alemquer, and Obidos,
the next station on the main line, is the last point touched in the State of
Para. It would not be right to leave unnoticed the rubber-gathering
industry, which is at once the wealth and the bane of this part of the
world. The implements in use are of the most primitive kind, as may
be judged by the samples on the table, but the average earnings can
easily be three pounds per day during the dry season, and the facility
of earning so much money with little exertion makes the inhabitants
unwilling to engage in more arduous labour. A narrow path leads
from the hut on the water's edge into the forest, from one rubber tree
to another, the path eventually returning to the hut. The trees are
cut on the morning round and the rubber is gathered in the afternoon.
As soon as it arrives at the hut, a fire of oily palm nuts (Attalea
Excelsa) is lighted and the thin sap thickened in the smoke. For this
purpose a paddle is used, on to which the sap is poured with a small
earthenware or tin vessel. The smoke soon thickens it and a new
layer is poured on, until the well-known flat cakes of india-rubber
have been formed. Owing to the rise of the river during the rainy
season, most of the huts have to be abandoned, and it can easily be
imagined how comfortless they are. Nearly all of them are built on
piles, and most of them are thatched with palm leaves. There is
hardly any attempt made to cultivate the soil, such as it is, but every-
thing is imported. The ss. " Cametense " in which the surveying
party went out, was laden with cabbages, onions and potatoes, part of
which went as far as Iquitos in Peru. Chiefly owing to this want of
provisions, and to the generally careless mode of life, the mortality
among india-rubber gatherers is very great. There are two stations
in the State of Amazonas — Parintins, formerly called Villa Bella da
Imperatriz, and Itacoatiara, formerly Serpa. Just before reaching
the former station the Serra de Parintins is passed, which forms the
boundary between the two States. At Parintins the river makes a
sudden bend, and the resulting eddy current greatly impeded the
work ; at Itacoatiara, on the other hand, the bow of the ship was run
ashore, and the end of the cable landed direct from the ship.

Before showing views of Manaos three pictures of the vegetation
taken at a short range will be thrown on the screen to illustrate the
luxuriance met with everywhere on the journey, but no attempt will
be made to describe it, as that has been done to perfection in the
classical works of Bates and Wallace. Everything they have said
in this respect remains as true as it was forty years ago, and hardly

Vol. XV. (No. 90.) Q

226 Mr. A. Siemens on Cable Laying on the Amazon Biver. [May 15,

anything new can be added to their description of the general
features of the Amazon valley; but the town of Manaos has com-
pletely changed its character since it was made the capital of that
region in 1853. A town quite European in its features has arisen in
the midst of the forest, and to the benefits of rapid transport — to
which it has owed so much — there is now added the characteristic
lever of modern progress, the annihilator of space and time — electrical
communication.

[A. S.]

1896-] Professor Ewing on Hysteresis, 227

WEEKLY EVENING MEETING,

Friday, May 22, 1896.

George Matthey, Esq. F.R.S. Vice-President, in the Chair.

Professor J. A. Ewing, M.A. F.R.S. Professor of Mechanism and
Applied Mechanics in the University of Cambridge.

Hysteresis,

(Abstract.)

The lecturer explained that the word hysteresis was not a term in
neuro-pathology. It had nothing to do with hysterics. The name
might be unfamiliar, but the thing it described was exceedingly
common. It was scarcely too much to say that hysteresis was to be
found everywhere, except, perhaps, in the dictionary.

The word was derived from the verb vcrrepeo), which signified to
lag behind. It was introduced about fourteen years ago to name a
characteristic which had been prominent in several researches into
the physical qualities of certain materials, especially of iron. The
name was invented at a time when the phenomenon of hysteresis had
no more than a purely scientific interest ; but in the rapid advance
of industrial electricity hysteresis had become a matter of much
commercial importance, and the word was now in common use by
electrical engineers. Certain materials, when causes acted on them
tending to change their physical state, had a tendency to persist in
their previous state. This tendency to persist was what constituted
hysteresis.

It was in connection with the magnetic properties of iron and
steel that the most conspicuous and practically the most important
manifestations of hysteresis were found. An experiment was shown
to illustrate hysteresis in the changes of magnetic condition brought
about by the application and removal of stress. An iron wire,
magnetised by a constant current in a surrounding coil, was hung up
and loaded with weights. The weights were alternately removed
and reapplied, and the magnetic state of the wire was shown by
means of a mirror magnetometer. It was seen that when the weights
were repeatedly put on and ofi", the magnetism changed from one to
another of two values ; but when half the weight only was left on
during unloading, the magnetism assumed a value much nearer to
the loaded than to the unloaded state ; whereas when half the weight
was put on after unloading, the magnetism took a value nearer the
unloaded than the loaded state. In other words, the magnetic efiects
of the loading lagged behind the changes in the loading itself. This

q2

228

Professor J. A. Ewing

[May 22,

lagging was shown to be static in character, for it was in no way
dependent on the rate at which the process of loading and unloading
was performed. Other cases of static hysteresis in the thermoelectric
and mechanical qualities of iron were mentioned.

Practically the most important instance was the hysteresis which
was observed when a piece of iron had its magnetism changed by
changing the magnetising force. When a piece of iron was first
magnetised, the magnetism B was developed by gradual increase of
the magnetising force H, in the way shown in Fig. 1. If at any
stage in the process, such as a, the magnetising force was made to
stop increasing, was reduced to zero, and was then reapplied in the
opposite direction, the magnetism changed in the way shown by the
curve acd of Fig. 2. And finally, if the magnetising force were
again reversed, so as to recover the direction and value it had at a,
the process followed was represented by the curve dea oi Fig. 3.

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Fig. 3.

The closed curve of Fig. 3 showed how the changes of magnetism
in this complete cycle of double reversal tended to lag behind the
changes of magnetising force. In consequence of this hysteresis,
energy was consumed in reversing the magnetism of iron, and it
could be proved that the energy consumed in each double reversal
was proportional to the area enclosed between the curves acd and
dea.

This was the process that went on in the iron cores of trans-
formers when used for electric lighting in the alternate-current
system of supply. The magnetic cycle was gone through something
like 100 times a second, and as a rule the transformer was in circuit
continuously by day and night. Whether it was supplying lamps
and doing useful service, or whether it was not, the waste of power
due to hysteresis went on. It formed a very serious item in the cost
of alternate-current supply, for the effect was that a large part of

1896.]

on Hysteresis.

229

the coal burnt at the central station, after having its energy passed
through a series of costly conversions, was devoted in the end to
nothing more than uselessly warming the transformers in the cellars
of consumers or in boxes under the streets. So long as iron could
not be found that was destitute of magnetic hysteresis, some loss on
this account was inevitable ; but it might be greatly lessened by
choosing a suitable kind of iron. Experience showed that some kinds
of iron had much less hysteresis than others. Thus in Fig. 4 the
curve marked I related to a specimen of iron eminently suitable for
use in transformers, while the curves marked II and III related to
other brands of iron. They enclosed much larger areas, and showed

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that the iron which gave them was to be avoided as having too much
hysteresis. Of late years some of the makers of iron had striven
with marked success to produce iron which should be comparatively
free from hysteresis, and it was now possible to obtain material
for transformers which reduced the loss to a fraction of what was
formerly thought inevitable.

The lecturer's magnetic curve tracer was exhibited in action,
showing magnetic curves, similar to Fig. 3, upon a screen by giving
to a small mirror simultaneous horizontal and vertical movements,
the former proportional to the magnetising force, and the latter to
the magnetisation of the specimen of iron in the machine. As a

Professor J. A, Ewing

[May 22,

230

convenient means of practically testing the quality of iron in this
respect tlie lecturer had lately introduced another instrument, which
was also shown at work. In this hysteresis tester (Fig. 5) the
sample of iron, in the form of a bundle of thin strips, was clamped
in a carrier and caused to rotate between the poles of a magnet
swinging on knife edges. As a consequence of hysteresis this
magnet was deflected, and its deflection, which was noted by means
of a pointer and scale, served to measure the hysteresis.

Fig. 5.

To show directly the heating effect of magnetic reversals in iron,
a differential air thermometer was used, with long bulbs, one of
which was partly filled by a bundle of iron wire. Both bulbs were
surrounded by coils, through which an alternating current passed.
The heating effect of the current itself was the same for both, but
the bulb containing the iron was further heated in consequence of
the hysteresis of the metal, and this additional heating was shown
by movement of a liquid index in a tube connecting the two bulbs.
It had even been proposed to apply the heating effect of hysteresis

1896.] on Hysteresis. 231

to the boiling of water. A kettle invented for this purpose by
Sir David Salomons and Mr. Pyke was exhibited.

In another experiment to illustrate the dissipation of energy
through magnetic hysteresis a steel ball was caused to roll down an
inclined railway formed by a slot cut in an iron tube. The tube was
wound longitudinally with a magnetising coil which caused lines of
magnetic induction to cross the slot. The ball was consequently
magnetised, and as it rolled the changes of magnetism in it and in
the neighbouring parts of the tube checked its motion, causing it to
slow down or stop when the current in the magnetising wire was
applied ; but the resistance due to hysteresis ceased when the current
was broken.

Fig. 6.

In conclusion the lecturer referred to the molecular theory of
magnetisation, which he had explained in a former lecture,* and to
the explanation it gave of magnetic hysteresis. Since then it had
received a remarkable confirmation from the work of Mr. F. G. Baily,
who had measured the hysteresis when iron discs were made to
revolve in a strong magnetic field. He found that when the field
was strengthened the hysteresis was at first increased, but a stage
was reached when the strengthening of the field ceased to increase
the hysteresis, and with a stronger field still the hysteresis was

* 'Proceedings,' Royal Institution, May 22, 1891.

232 Professor J. A. Ewing on Hysteresis, [May 22,

actually reduced. Indeed, by a small further increase of the field
the hysteresis could be made to practically vanish. This very
curious result had been predicted originally by Mr. James Swinburne,
as a consequence of the lecturer's theory, and had at that time seemed
so unlikely that it was urged as an objection to the theory. It had
now been proved to afford the theory the strongest possible con-
firmation.

A model was shown in illustration of this point, in which a glass
plate carrying a number of small pivoted magnets (Fig. 6) was made
to revolve slowly in a magnetic field produced by two neighbouring
coils. So long as the field was weak the small magnets formed
groups which were broken up during the revolution, thereby dis-
sipating energy and exhibiting hysteresis ; but when the field was
sufficiently strengthened the small magnets continued to point one
way without forming groups, for their mutual magnetic forces were
then masked by the external or field force. There were consequently
then no unstable phases in the motion and no hysteresis.

Hysteresis in the magnetic quality of iron was to be ascribed to
the formation of stable groups of molecules, in consequence of the
mutual forces which the molecules exerted on one another in virtue
of their magnetic polarity. It might very well be that in other
manifestations of hysteresis, such, for example, as the familiar
phenomenon of friction between two solid surfaces when rubbing
against one another, the resistance and consequent dissipation of
energy were similarly due to the forming and breaking up of molecular
groups, the molcules being mutually constrained by some other
species of polar forces, possibly due to electrostatic charges upon
them.

[J. A. E.]

1896.] Mr. Augustine Birrell on John Wesley. 233

WEEKLY EVENING MEETING,

Friday, May 29, 1896.

The Right Hon. Lord Halsbury, M.A. D.C.L. F.R.S. Manager,
in the Chair.

Augustine Birrell, Esq. Q.C. M.P.

John Wesley : Some Aspects of the Eighteenth Century.
(Abstract.)

The lecturer said that when he thought of the eighteenth century as
it was lived in England in town and country, he found it difficult to
reconcile all that he read about it with any sweeping description,
condemnation or dominant note. It was a century of violent con-
trasts. It was a brutal age, for the press-gang, the whipping-post,
gaol fever, all the horrors of the criminal code were among its
characteristics. It was an ignorant age, for a great part of the popu-
lation gave itself up to drunkenness and cock-fighting ; a corrupt
age, when offices were bought and sold and every man was supposed to
have his price. Brutal, ignorant and corrupt, the eighteenth century
was all these — was it not written in the storied page of Hogarth?
And yet, too, there was plenty of evidence of enthusiasm, learning
and probity. The life of John Wesley, who was born in 1703 and
died in 1791, covered practically the whole of the eighteenth century,
of which he was one of the most remarkable and strenuous figures,
and his Journal was the most amazing record of human exertion ever
penned by man. Those who had ever contested a Parliamentary elec-
tion would know how exhausting was the experience ; yet John Wesley
contested the three kingdoms in the cause of Christ, and during that
contest, which lasted forty-four years, he paid more turnpike toll than
any man who ever lived. His usual record of travel was 8000 miles
a year, and even when he was an old man it seldom fell below 5000
miles. The number of sermons he preached had been estimated at
40,500. Throughout it all he never knew what was meant by de-
pression of spirits. Wesley was not popular with historians ; he put
the historian out of conceit with himself. It might be said that
Wesley's personal character lacked charm, but it was not easy to
define charm ; nobody ever had defined it, and nobody who was wise
ever would try to do so. But, charm or no charm, Wesley was a
great bit of the eighteenth century, and was therefore a great
revealing record of the century. He received a good classical educa-
tion, and remained all his life very much of the scholar and the

234 Mr, Augustine Birrell on John Wesley. [May 29,

gentleman. He was a man of very wide reading, and his judgments
on books were not only "polite" but eminently sane and sbrewd.
His religious opinions, and his extraordinary credulity in some
matters, in no way affected the perfect sanity of his behaviour or the
soundness of his judgment. He was a cool, level-headed man, and
had he devoted his talents to any other pursuit than that of spreading
religion he must have acquired a large fortune. He knew that he
would have succeeded in other walks of life, but from the first day of
his life almost he learnt to regard religion as his business. In his
Journal he never exaggerated, or never seemed to do so ; the England
he described was an England full of theology and all sorts of queer
vague points, and strange subjects were discussed in all places — of
some of them the very phraseology was now as extinct as the wolf, or
at least as rare as the badger. Although not over well disposed, as
his life went on, towards the clergy of the Establishment, he very
seldom recorded any incidents of gross clerical misbehaviour. In
spite of the rudeness of the manners of the people, Wesley's sufferings
were really nothing to those with which Parliamentary candidates had
had to put up for centuries. What would really shock the reader of
his Journal was his description of what might be called the public
side' of the country — the state of its gaols or its criminal code, the
callous indifference of the magistracy, the indifference of the clergy to
what might be called missionary effort. Wesley's Journal was a
book which ought to be kept in mind as a means of knowledge of the
eighteenth century, just as much as ' Tom Jones ' was a means of
knowledge or as Hogarth was. As one read his Journal one was con-
strained to admire the magnificence of the vigour, the tremendous
force of the devotion and the faith which kept John Wesley in per-
petual motion for more than half a century, and one felt glad to be
able to place that Journal beside Walpole's letters and Boswell's
Johnson, and to know that in it there were some aspects of the
eighteenth century that could not be found elsewhere.

[A.B.]

1896.]

General Monthly Meeting.

235

GENEKAL MONTHLY MEETING,

Monday, June 1, 1896.

Sir James Ckiohton-Browne, M.D. LL.D. F.R.S. Tr
Vice-President, in the Chair.

William Phipson Beale, Esq. Q.C. F.G.S.

Miss Esther Bright,

Edward Ball Knobel, Esq. Treas. K. A.S.

were elected Members of the Royal Institution.

The following Address to the Right. Hon. Lord Kelvin was read
and adopted, and authorised to be signed by the President on behalf
of the Members : —

" To the Eight Hon. Lord Kelvin, D.C.L. LL.D. F.R.S. F.R.S.E. Grand
Officer of the Legion of Honour, Professor of Natural Philosophy, University of
Glasgow, Manager and Vice-President, Royal Institution of Great Britain.

" The Members of the Royal Institution of Great Britain beg leave to offer to
your Lordship their cordial congratulations on the occasion of the Jubilee of your
appointment to the Chair of Natural Philosophy in the University of Glasgow,
and desire to express their high appreciation of the conspicuous services you
liave rendered during your incumbency of that chair in the Extension and
Diffusion of Scientific Knowledge, which it is the main object of the Royal
Institution to promote.

" Recognising as the Members of the Royal Institution do the incalculable
and far-reaching value of your researches and labours in connection with elec-
tricity, magnetism, the atmosphere, heat and vortex motion, and the immediate
practical utility of your ingenious inventions, in aiding further scientific investi-
gation and in enlarging and quickening human intercourse, they wish more
especially to acknowledge the benefits you have conferred on the Royal Institu-
tion by the admirable lectures which you have, from time to time, delivered
within its walls. Your first lecture, " On the Origin and Transformations of
Motive Power," was given on the 29th of February, 1856, when the late Sir
Henry Holland occupied the Chair ; and your last lecture, on " Isoperimetrical
Problems," was given on May I2th, 1893, when the chair was filled by Sir
Douglas Galton, K.C.B.

"In the thirty-seven years intervening between these dates — a period of
intense and fruitful scientific activity — you have addressed the Members of the
Royal Institution fifteen times, your lectures having been as Mirrors and Recorders
in reflecting and measuring the advances achieved in mathematics and physics.

" The Members of the Royal Institution rejoice to think that besides con-
tributing more than any man now living to the progress of Science, you have
likewise secured it a higher place in public estimation than it has hitherto
attained, and they earnestly hope that you will be long spared to wear the
honours which have been so deservedly conferred upon you."

It was Resolved, That Sir Frederick Bramwell, Bart, and
Professor Dewar be appointed delegates from the Royal Institution
to present this Address.

236 General Monthly Meeting. June 1,

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

The Secretary to Government^ PMn/a&— Eeport on the Sangla Tobba. By C. J.

Eogers. fol.
The Secretary to Government, General Department, Bombay — Progress Report of

the Archaeological Survey of Western India (Bombay) for 1894-95. fol.
The Meteorological Office — Report of the Meteorological Council for 1895. 8vo.

1895.
Accademia dei Lincei, Eeale, Roma — Atti, Serie Quinta : Rendiconti. Classe di
Scienze Morali, etc. Vol. V. Fasc. 3. 8vo. 1896.
Classe di Scienze Fisiche, etc. Vol. V. Fasc, 8, 9. 8vo. 1896.
American Geographical Society — Bulletin, Vol. XXVIII. No. 1 . 8vo. 1896.
Astronomical Society, Royal — Monthly Notices, Vol. LVI. No. 7. 8vo. 1896.
Aubrey, W. H. 8. Esq. LL.D. (the Author) — Stock Exchange Investments ; the

theory, methods, practice and results. 8vo. 1896.
Bankers, Institute o/— Journal, Vol. XVII. Part 5. 8vo. 1896.
Batavia 06ser?;ator?/— Rainfall in the East Indian Archipelago, 1894. 8vo. 1895.

Observations made at the Magnetical and Meteorological Observatory at
Batavia, Vol. XVI I. 4to. 1895.
Boston, U.S.A., Public Library— Forty -iourth Annual Report, 1895. 8vo. 1896.
Botanic Society, Royal — Quarterly Record, No. 65. 8vo. 1896.
British Architects, Royal Institute o/— Journal, 1895-96, Nos 13, 14. 8vo.
British Museum Trustees — Index of Artists represented in the Department of
Prints and Drawings, Vol. II. (French School). 8vo. 1896.

Catalogue of Seals in the Department of Manuscripts, Vol. IV. 8vo. 1895.

Catalogue of Greek and Etruscan Vases, Vols. III. IV. 8vo. 1896.
Cambridge Philosophical Society — Proceedings, Vol. IX. Part 2. 8vo. 1896.
Camera Club— Journal for May, 1896. 8vo.

Chemical Industry, Society o/— Journal, Vol. XV. No. 4. 8vo. 1896.
Chemical Society — Journal for May, 1896. 8vo.

Proceedings, Nos. 164, 165. 8vo. 1896.
Editors — American Journal of Science for May, 1896. 8vo.

Analyst for May, 1896. 8vo.

Anthony's Photographic Bulletin for May, 1896. Svo.

Astrophysioal Journal for May, 1896. Svo.

Athenaeum for May, 1896. 4to.

Author for May, 1896.

Bimetallist for May, 1896.

Brewers' Journal for May, 1896. Svo.

Chemical News for May, 1896. 4to.

Chemist and Druggist for May, 1896. Svo.

Education for May, 1896. Svo.

Electrical Engineer for May, 1896. fol.

Electrical Engineering for May, 1896.

Electrical Review for May, 1896. Svo.

Electric Plant for May. 1896. 8vo.

Engineer for May, 1896. fol.

Engineering for May, 1896. fol.

Engineering Review and Metal Worker for May, 1896. 8vo.

Homoeopathic Review for May, 1896.

Horological Journal for May, 1896. Svo.

Industries and Iron for May, 1896. fol.

Invention for May, 1896. Svo.

Law Journal for May, 1896. Svo.

Machinery Market for May, 1896. Svo.

Nature for May, 1896. 4to.

1896.] General Monthly Meeting. 237

Editors — continued.

Nuovo Cimento for April, 1896. 8vo.
Pliysical Keview for May- June, 1896. Svo.
Science Siftings for May, 1896. Svo.
Scientific African for May, 1896. Svo.
Scots Magazine for May, 1896. Svo.
Technical World for May, 1896. Svo.
Transport for May, 1896. fol.
Tropical Agriculturist for April, 1896. Svo.
Work for May, 1896, Svo.
Zoophilist for May, 1896. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXV. No. 122. 1896.

Svo.
Ellis, H. D. Esq. M.A. M.B.I, (tlie ^wf/ior)— Graphic Arithmetic Charts, fol.
Essex County Technical Laboratories, Chelmsford — Journal for April-May, 1896.

Svo.
Fleming, J. A. Esq. M.A. F.R.S. (the Author)— The Alternate Current Trans-
former in Theory and Practice : (Vol. I. The Induction of Electric Currents.)
New edition. Svo. 1896.
Florence, Biblioteca Nazionale Centrale — Bollettino, Nos. 248, 249. Svo. 1896.
Florence, Reale Accademia dei GeorgofiU — Atti, Vol. XVIII. Disp. 3, 4 ; Vol. XIX.

Disp. 1. Svo. 1895-96.
Franldin Institute— J OMin&\ for May, 1896. Svo.

Geographical Society, J?o?/aZ— Geographical Journal for May, 1896. Svo.
Geological Society — Quarterly Journal, No. 206. Svo. 1896.
Harlem, Muse'e 3 ei/Zer— Archives, Se'rie II. Vol. V. Part 1. Svo. 1896.
Harlem, Societe Hollandaise des Sciences — Archives Ne'erlandaises, Tome XXX.

Livr. 1. Svo. 1896.
Imperial Institute— Impenol Institute Journal for May, 1896.
Iowa, Laboratories of Natural History— JiwWetin, Vol. III. No. 4. Svo. 1896.
Johns Hophins University — University Studies, Fourteenth Series, Nos. 4, 5. Svo.
1896.
American Chemical Journal, Vol. XVIII. No. 5. Svo. 1896.
Kew Observatory — Report of the Kew Observatory Committee of the Royal Society

for 1895. Svo. 1896.
Life-Boat Institution, Royal National— Aiinvi&l Report for 1896. Svo.
Lisbon, Royal Observatory — Observations me'ridiennes de la Planete Mars pendant

I'opposition de 1892. 4to. 1895.
London County Council Technical Education Board — London Technical Educa-
tion Gazette for May, 1896. Svo. 1895.
Madras Observatory — Daily Meteorological Means. 4to. 1896.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Fourth

Series, Vol. X. No. 3. Svo. 1896.
Manchester Steam Users' Association — Boiler Explosions Acts, 1882 and 1890,

Reports, Nos. 764-877. Svo. 1895.
Massachusetts Institute of Technology — Technology Quarterly and Proceedings of

the Society of Arts,' Vol. VIII. No. 4. Svo. 1895.
Mechanical Engineers, Institution of — Proceedings, 1895, No. 3. Svo.
Meteorological Society, Royal — Meteorological Record, No. 59. Svo.

Quarterly Journal, No. 98. Svo. 1896.
Microscopical Society, Royal — Journal, 1896, Part 2. Svo.
Navy League—'' The Navy League." Svo. 1896.

Navy League Journal, April-May, 1894. 4to.
New South Wales, Agent- General for — New South Wales Statistical Register for

1894 and previous years. Svo. 1896.
Numismatic Society — Numismatic Chronicle, 1896, Part 1. Svo.
Paris, Societe Franraise de Physique — Bulletin, No. 79. Svo. 1896.
Pharmaceutical Society of Great Britain — Journal for May, 1896. Svo.
Photographic Society, Royal — The Photographic Journal for April, 1896. Svo.

238 General Monthly Meeting. [June 1,

Physical Society of London — Proceedings, Vol. XIV. Part 5. 8vo. 1896,

Borne, Ministry of Fuhlic WorJis — Giornale del Genio Civile, 1896, Fasc. 2. And
Designi. fol.

Boyal Society of London — Philosophical Transactions, Vol. CLXXXVII. A,
Nos. 174-7. 4to. 1896.
Proceedings, No. 356. 8vo. 1896.

Sanitary Institute — List of Members, &c. 1896. 8vo.
Journal, Vol. XVII. Part 1. 8vo. 1896.

Saxon Society of Sciences, Royal —
Mathematisch-Physische Classe —

Berichte, 1896, No. 1. 8vo. 1896.
Philologisch-Historische Classe —
Abhandlungen, Band XVII. No. 4. 8vo. 1896.

Selborne Society — Nature Notes for May, 1896. 8vo.

Society of Antiquaries — Archseologia, 2 S. Vol. IV. Part 2. 4to. 1895.

Society of Arts—Joumol for May, 1896. 8vo.

Sweden, Royal Academy of Sciences — Ofversigt, Vol. LII. 8vo. 1896.

Tacchini, Professor P. Hon. M.R.I, (the Author) — Memorie della Societb, degli
Spettroscopisti Italiani, Vol. XXV. Disp. 4, 5. 4to. 1896.

United Service Institution, Royal — Journal for May, 1896. 8vo.

University of London— Calendar for 1896-97. 8vo. 1896.

Vaughan, Henry, Esq. M.R.I. — The Art of Ancient Egypt : A Series of Photo-
graphic Plates representing objects from the Exhibition of the Arts of
Ancient Egypt at the Burlington Fine Arts Club in 1895. (Privately
Printed for Subscribers.) 4to. 1895.

Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1896,
Heft 4. 4to.

Victoria Institute— Journal of the Transactions, No. 111. 8vo. 1896.

Vienna, Geological Institute, Royal — Verhandlungen, 1896, Nos. 4, 5. 8vo.

Yorkshire Philosophical Society — Annual Eeport for 1895. 8vo. 1896.

Zoological Society of London — Report of the Council for 1895. 8vo. 1896.

1896.] Professor Fleming on Electric Research, 239

WEEKLY EVENING MEETING,

Friday, June 5, 1896.

The Eight Hon. Loed Kelvin, D.C.L. LL.D. F.R.S. Vice-President,

in the Chair.

Professor J. A. Fleming, M.A. D.Sc. F.R.S. M.BJ.

Electric and Magnetic Besearch at Low Temperatures,

During the last four years much time has been spent by Professor
Dewar and by me in the prosecution of a joint research on the
principal electric and magnetic properties of metals at very low-
temperatures. Some reference has already been made in previous
discourses by Professor Dewar to portions of this work,* but the
special object of the present lecture is to extend these descriptions,
and put you in possession of the latest results in this department of
the low temperature investigations. It will be convenient to discuss
the several divisions of it in the order in which they have engaged
our attention.

One hundred and sixty-seven years ago Stephen Gray, a pensioner
of the Charterhouse, in conjunction with his friend Granvile Wheler,
stretched a packthread 300 feet long over silk supports, and demon-
strated that an electrification of the thread at one end spread instantly
over the whole mass, but that if metal wires replaced the silk no
electrification of the thread was possible. This experiment undoubtedly
formed the starting-point for the first definite recognition of the
necessity for a classification of bodies into insulators and conductors,
a distinction which Gray's brilliant contemporary, Dufay, extended
and confirmed, and for which he and Desaguiliers coined these familiar
terms.j Gray's contributions to knowledge as an epoch-making
discoverer have received less notice from scientific historians than
their real value deserves. It is less easy to state who first noticed
that the powers of conduction and insulation were greatly affected by
temperature. Cavendish, in 1776, however, was perfectly familiar
with the fact that solutions of common salt conduct electricity better
when warm than when cold,J and made measurements of the relative

* ' Scientific Uses of Liquid Air.' A Friday Evening Discourse, by Pro-
fessor J. Dewar, LL.D. F.K.S. delivered at the Eoyal Institution, Jan 19, 1894.

t See the 'Intellectual Rise in Electricity,' by Park Benjamin. Stephen
Gray's papers on this subject, communicated to the Eoyal Society, are as follows :
Phil. Trans. 1720, vol. xxxi. p. 104; 1731, vol. xxxvii. p. 18; 1732, vol. xxxvii.'
p. 285 ; 1735, vol. xxxix. p. 16 ; 1736, vol. xxxix. p. 400. See also Dufay, Phil
Trans. 1733, No. 431, p. 258.

X See the ' Electrical Researches of Cavendish.' Edited by Clerk-Maxwell
p. 324.

240

Professor Fleming

[June 5,

resistances of an iron wire and a salt solution which were marvellously
accurate, when we consider that his only means of measurement was the
comparison of electric shocks taken through the bodies to be examined.
Not until after the invention of the battery and galvanometer was
it clearly proved that differences exist between the conducting powers
of metals; but by Davy, Becquerel, Ohm, Pouillet, Fechner and
others all the fundamental facts were ascertained, and the classical
researches of Wheatstone and later of Matthiessen gave us the accurate
lavrs and constants of electrical conduction. By these investigations
it was shown that in the case of electric conduction through metallic
wires of uniform sectional area their total resistance was proportional
to the length, inversely as the cross section, and also proportional to
a specific constant for each material called its resistivity. Moreover,
it was found that this resistivity was considerably affected by tem-
perature, generally being increased in metals by rise of temperature,

and decreased for carbon, electro-
lytic liquids and many badly con-
ducting bodies.

Although much knowledge of
the behaviour of pure metals and
alloys in regard to electric con-
duction has thus been accumu-
lated, we considered that it would
be of great scientific interest to

examine with care the changes
occurring in the conductivity of
these bodies, or reciprocally in
their resistivity, when cooled to
temperatures of two hundred
degrees or more below the Cen-
tigrade zero by the aid of liquid
oxygen and liquid air.* Knowing the great influence of very
small quantities of impurity on this quality, our first attention was
directed to obtaining samples of alloys and metals in a state of great
chemical purity, in giving to wires drawn from them a suitable form,
and in devising a convenient support or holder by which the electrical
resistance of the wire might be measured when immersed in liquid
oxygen or liquid air, either in quiet ebullition in an open vessel, or
under reduced pressure in a closed one. It will be unnecessary to
dwell on the difficulties surrounding the preparation of these
accurately drawn metallic wires of pure metal. Suffice it to say
that our obligations to Mr. George Matthey, Mr. Edward Matthey,
Mr. J. W. Swan and other friends were very great with respect to

* Almost the only experimental work previously clone in this subject seems
to have been that of Cailletet and Bouty (' Journal de Physique,' July 1885), on
the ' Kesistance of Metals at - 100° C.,' using ethylene as a refrigerating agent ;
and a research by Wroblewski, on the 'Resistance of Copper at very Low
Temperatures' ('Comptes Rendus,' 1885, vol. ci. p. IGl).

Fig. 1.
Low temperature resistance coil.

1896.]

on Electric Besearch at Low Temperatures,

241

this portion of the work. The final outcome of all failures was the
production of a resistance coil of the following form: — Two thick
wires of high conductivity copper about 3 or 4 mm. thick are bent
as shown in Fig. 1, and wrapped round the lower part with a cylin-
drical sheath of thin vulcanised fibre laced to them by a silk thread.
On this sheath, which generally had the form of an oval cylinder, a
paraffined silk cord was spirally wound so as to leave a helical groove.
In this groove was coiled the resistance wire, of known length and
section, and its ends were attached by solder to the ends of the thick
copper leads. The wire was wound a little loosely in the groove so
as to allow for the great contraction which takes place in cooling,
and yet the wire was exposed so as to take up instantly the tempera-
ture of the bath, whilst at the same time the mass of material to be
cooled down was rendered as small as possible. The length of wire
employed was generally about one or two metres, and the diameter
from about one-twelfth to half

a millimetre ('003 inch to
•02 inch). These mean dia-
meters were -measured by
the microscope micrometer at
about fifty to one hundred
places for each metre length
of the wire. Having thus
prepared a great collec-
tion of resistance coils of
pure metals and alloys, each
in the form of a wire of
known length and mean dia-
meter, the next operation was
the measurement of their re-
sistance at definite tempera-
tures. For the sake of those not
fully familiar with the details

Coil.

Resistance,

Fig. 2.

Diagram of arrangement of circuits for
comparing resistances by means of the
differential galvanometer.

of electrical measurement, a moment's
digression may be made to explain two of the principal methods in
use. Becquerel's work was chiefly conducted v^ith the difi'erential
galvanometer. In this instrument two coils of wire of exactly equal
length are coiled on one bobbin, in the centre of which hangs a small
magnetic needle. The current from a battery (see Fig. 2) divides
at one point, and flows along one path through the conductor or
conductors under examination and through one coil (No. 2) of the
galvanometer. The other portion of the current flows through a wire
of variable length called a rheostat, and through the other coil of the
galvanometer, equal in every respect to the first coil, but circulates
rpund the needle, N.S., in an opposite direction to that of the current
in the first coil. Hence, if the currents are of equal strength the
needle is not disturbed at all from its zero position. We can make
these currents equal by adjusting the length of the wire of the
rheostat so that its resistance is equal to the resistance of the coil
Vol. XV. (No. 90.) r

242 Professor Fleming [June 5,

being tested. By this means it is easy to verify all the ordinary laws
of conduction. We can, for instance, show at once that by cooling
an iron wire in iced water its resistance is decreased, whereas in
cooling the carbon filament of a glow-lamp its resistance is increased.
This method is not generally so convenient as the arrangement
first described by Mr. Hunter Christie to the Royal Society in 1833,
re-devised ten years later by Wheatstone in 1843, and which has been
always curiously misnamed the " Wheatstone's Bridge," even in sj)ite
of Wheatstone's own declaration that he did not invent it.* In this
arrangement (see Fig. 3) the current from a battery B has two paths
open to it by which to complete its circuit, and we employ a galvano-
meter with a single coil to discover two points on these two circuits
which are at equal potentials. When these two points are connected
the galvanometer needle is undisturbed, and it is a simple matter to
show that under these circumstances the numerical values of the elec-
trical resistances of the two segments A X, X D, of the circuit A D,
denoted by P and Q, and the resistances E and S which form the

Fig. 3.
Wheatstone's Bridge arrangement for comparing resistances.

other branch, are to one another in simple proportion as R is to S —
that is, P is to Q as R is to S. In actual work, one form, useful for
lecture purposes, which this arrangement takes is that known as the
slide wire bridge (see Fig. 4), and which is before you. In this con-
struction the battery current flows partly through a uniform wire a h,
stretched over a scale, and partly through a standard resistance 11',
and the resistance R to be tested placed in series with it.

We employ a galvanometer G to connect the middle point between
R and R' with some point on the slide wire, and we can always find
a point on the slide wire such that no current flows through the gal-
vanometer. The ratio of the unknown resistance R is to that of the
known standard resistance R' in the ratio of the lengths of the two
sections into which the contact piece divides the slide wire. Hence
R is determined in terms of R'. Another form of this appliance in
which all three arms of the bridge consist of coils of wire capable of

* See Phil. Trans. 1833, Mr. S. Hunter Christie, on the 'Experimental
Determination of the Laws of Magneto-Electric Induction.' See also Wheatstone's
Scientific Papers, p. 129, 'An Account of several new instruments for determining
the Constant of a Voltaic Circuit,' Phil. Trans, vol. cxxxiii. p. 303, 1843.

1896.]

on Electric Besearch at Loiv Temperatures.

243

being joined, as required, in series with each other by plugs, is most
commonly used, and it was a most carefully adjusted Elliott bridge of
this last pattern which we employed.

All our resistance measurements have been reduced to express
them in terms of the International ohm, as defined by the Board of
Trade Committee, and obtained by reference to standard coils care-
fully standardised for us at Cambridge. By this means the whole of
our wires were measured at five definite temperatures, viz. at about
200° C. ; at the temperature of boiling water, 100° C. ; at the tem-
perature of melting ice, 0° C. ; at the temperature of solid carbonic
acid melting in ether, which gives a temperature of about —78° C. ;
and at the temperature of liquid oxygen boiling under a pressure of
760 mm.j which gives a temperature of —182° C.

Fig. 4.
Slide wire bridge. Lecture form.

In this last case the coils were immersed in liquid oxygen con-
tained in suitable vacuum-jacketed vessels. In this connection, I
should like to express with due emphasis the opinion that none of
this low temperature research would have been possible at all with-
out the assistance of Professor Dewar's most valuable invention the
glass vacuum-jacketed silvered vessel. For much of this work it has
been necessary to employ many litres of liquid oxygen and air at a
time, and to be able to keep it for hours in a state of perfect qui-
escence and absolutely constant temperature, and in no way could
this have been done without this beautiful and scientific device.

Before describing the results of these experiments it may be
interesting to exhibit a few of the principal facts. The most strik-
ing of them is the very great reduction in electrical resistance, or
increase in conductivity, experienced by all the pure metals when
cooled in liquid air. Here, for instance, are two coils of iron wire :
balancing them on the bridge we find them to be of exactly equal
resistance, but if one of the coils is cooled in liquid air its resistance
is reduced to about one-tenth of its resistance at the ordinary tem-

r2

244 Professor Fleming [June 5,

perature of the air. We may also compare the resistances of these
two similar iron coils, when one is placed in boiling liquid air and
the other in boiling water. The resistances, instead of being in the
ratio of one to one, are now in the ratio of one to twelve. Again, if
we take two wires, one of pure iron and one of pure copper, of exactly-
equal length and equal section, we find that at ordinary temperatures
(15° C.) the iron wire has about six times the resistance of the coj)per :
but if we cool down the iron wire in liquid air to — 186° C, still
keeping the copper coil at the ordinary temperature (15° C), we now
find that the iron coil has actually become a much better conductor
(about 30 per cent, better) than the copper.* On the other hand, if
we examine the behaviour of this coil of German silver, which is a
copper-zinc-nickel alloy, or of this platinum-silver coil, we find that
the cooling down through 200° has a comparatively small effect upon
its electrical resistance. We thus see that whilst pure metals have
their electrical resistance immensely decreased by cooling to the
temperature of liquid air, alloys generally do not experience anything
like so great a change.

A word or two must next be said on the manner in which
we have represented graphically all the results of our experiments.
We desired to delineate lines on a chart so as to express the
change in specific resistance of all our metals and alloys in terms of
temperature ; and the question then arises, how was the temperature
measured ? You already know that an ordinary thermometer,
whether mercury, alcohol, or air, would be useless to measure tem-
peratures at which even air liquefies under ordinary pressures.

The employment of the constant pressure hydrogen thermometer
with reduced pressure would have given us temperature readings very
approximately those of the absolute thermodynamic scale, but the
experimental difficulties of its use would have been enormous. We
preferred to use the platinum resistance thermometer, and to express
our temperatures in platinum degrees as follows : — Our experience
has shown us that a pure soft annealed platinum wire may be cooled
as often as necessary to the lowest attainable temperatures, and yet
will always have the same resistance when measured again at other
constant temperatures. Availing oui'selves of this fact, we have used
in all this work a low temperature platinum thermometer made in
the following way : — A well-annealed platinum wire is made into a
resistance coil, as already described. Its resistance is carefully
measured at the temperature of boiling water, 100° C, and melting
ice, 0° C. From these measurements we construct a scale of tempera-
ture as follows : — A horizontal line A E (see Fig. 5) is taken on
which to mark off temperature, and any two points A and B are
taken on this line and the length A B divided into one hundred
equal parts. At these points B and A perpendiculars are set up

* The exact resistances of the coils used for the experiment were as follows :
Iron at 16° C. = 7*003 ohms, and reduces to 0*711 ohms; at - 186° C. copper
at 16° = 1*169 ohms, reduces to 0-2033 at - 186° C.

1896.]

oa Electric Eesearch at Loio Temperatures.

245

proportional to the resistance of the platinum wire at 0° C. and at
100° respectively, and through the tops of these perpendiculars a
sloping straight line is drawn until it cuts the axis of temperature at
E. The graduation of the horizontal line is continued in both
directions on the same scale as the subdivision of the line between
the points marked 0 and 100. To measure and define any other
temperature, say, for instance, the boiling-point of liquid oxygen
under a pressure of 760 mm., we have simply to measure the resist-
ance of the platinum wire in the liquid oxygen. We then look out
on the chart the ordinate which has the same numerical value as the
resistance of the wire in the oxygen, and at the foot of that ordinate

J/

y

/

/

y

y

SE

u

<^ U-

Q j

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u.

O 111

in

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I?

1
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-l£

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3 10

0

Fig. 5.
Method of constructing a scale of platinum temperature,

we find a number, viz. ( — 197), which is the temperature of the liquid
oxygen on this platinum scale.

Two questions then arise — first, Do all annealed platinum wires
give, when used in this way, the same numerical values for definite
and identical temperatures ? The answer to this is, Nearly, but not
quite. In the case of two thermometers much used by us, the differ-
ence was about half a degree at — 100° C, the boiling-point of liquid
ethylene. Into this matter it is not possible here to enter more fully ;
suffice it to say that we have invariably referred our temperature
measurements to one standard thermometer. The second question is
equally important — it is, What is the relation of the scale of tempera-
ture so defined to the absolute thermodynamic scale; or, which is
very nearly the same thing, to the scale of temperature defined by a
constant pressure hydrogen thermometer ? If the air thermometer
and platinum thermometer readings are made to agree at 0° C. and
100° C, then a temperature which would be called 50° on the
Centigrade scale would be denoted by 50*4 nearly on the platinum
thermometer spale, and corresponding to - 78° on the Centigrade
scale, which is the temperature of carbonic acid melting in ether.

246

Professor Fleming

[June 5,

The platinum temperature by our standard is -81°-9; and corre-
sponding to - 182" C, whicli is very nearly the Centigrade tempera-
ture of liquid oxygen boiling at the normal pressure of 760 mm. ;
the platinum temperature by the same standard is - 197°. The
conversion of these numbers representing low temperatures in
platinum degrees into the numbers representing the corresponding
absolute thermodynamic temperatures is a work we have reserved for
a future research ;* but meanwhile it may be said that there is no
method of measuring low temperatures which is so easy of applica-
tion and so accurate as that depending on the use of a platinum
thermometer. All our work has been ultimately referred to one
standard platinum thermometer, which we call P^.

A suggestion may here be made. There is no reason why the Board
of Trade electrical laboratory should not possess a standard platinum
thermometer defining officially platinum or absolute temperatures for
all time, and with which other platinum thermometers could be easily
and very accurately compared.

Having thus defined our scale of temperature, we proceeded to
embody the whole of our results in a chart which is now before you
(see Fig. 6), and in which vertical distances represent resistivity, or
specific resistance, or the resistance in absolute measure per cubic
centimetre of the various metals, and horizontal distances represent
platinum temperatures. The curves indicate the manner in which
the resistivity varies with temperature for each substance.

The values of the resistivity of most ordinary metals and alloys
are given in the table adjoining : —

Electrical Kesistivity of Puee Annealed Metals.

Metal.

Resistivity

Percentage

in C.G.S.

increment.

units at 0° C.

0° to 100° C.

1,468

40-0

1,561

42-8

2,197

37-7

2,665

43-5

4,355

38-1

5,751

40-6

9,065

62-5

10,023

41-9

10,219

35-4

10,917

36-69

12,323

62-2

13,048

44-0

17,633

39-8

20,380

41-1

94,070

38-88

108,000

—

Atomic
volume.

Silver ..
Copper
Gold ..
Aluminium
Magnesium
Zinc ...
Iron

Cadmium
Palladium
Platinum
Nickel . .
Tin .. ,
Thallium ,
Lead ..
Mercury
Bismuth

10-04

7-10

10-04

10-56

13-76

9-12

7-10

12-96

9-12

9-12

6-94

16-20

17-20

18-27

14-56

21-43

* Callendar has shown that over a wide range of temperature from 0° C. to
700° C. the difference between the platinum temperature and the air thermometer
temperature is a parabolic function of the absolute temperature.

1896.] on Electric Besearch at Low Temperatures,

Electrical Resistivity op Alloys.

247

Alloy.

Aluminium-copper . .

Alumiuium-titunium

Aluminium-silver

Gold-silver

Copper-aluminium ..
Copper-nickel-aluminium
Platinum-rhodium . .

Nickel-iron

German silver . .
Platinum-iridium
Platinum-silver ..

Platinoid

Manganin

Iron-manganese . .

Composition.

94 : 6

94 : 6

90 : 10
97 : 3
87 : 61 : 6h
90 : 10 "^

95 : 5

Ptjr

: 12

Resistivity Percentage

in C.G.S. increment,

units at 0° C. O'^ C. to 100° C.

2,904

3,887

4,641

6,280

8,847

14,912

21,142

29,452

29,982

30,896

31,582

41,731

46,678

67,148

38-1
29-0
23-8
12-4
8-97
6-45
14-3
20-1
2-73
8-22
2-43
31
0-
12-7

The first thing which strikes us on looking at the chart (Fig. 6) is
that the lines for the pure metals all converge downwards in such a
manner as to indicate that their electrical resistance would vanish at
the absolute zero of temperature, but that no such convergence is
indicated in the case of alloys. We have found that the slightest
impurity in a metal changes the position of the resistance line. lu
the next place, note that the order of conductivity is different at low
temperatures to that at ordinary temperatures. At 13° C. pure
silver is the best conductor, but at - 200° pure copper is better
than silver, and the position of mercury is, of course, very
different.

Again, the lines of some metals are very much curved. The
principal magnetic metals, iron and nickel, have lines which are
very concave upwards, and this is a characteristic apparently of many
magnetic alloys. The mean temperature coefficient of these magnetic
metals between 0° C. and 100° C. is much larger than that of other
metals, and the percentage decrease in resistance in cooling them
from + 200° C. to — 200° C. is greater than in the case of any other
metal. It is worth noting in passing that these magnetic metals,
iron and nickel, have smaller atomic volumes than any other metal,
and that, generally speaking, the worst conductors amongst the metals
are those that have the large atomic volumes and large valency.

Next turning to alloys, we may make mention of a few general
facts with regard to their resistance. If to one pure metal we add a
small quantity of any other metal the result is always to raise the
resistance line almost parallel to that of the predominant constituent.
Thus, in our own chart, the alloy consisting of 6 per cent, of copper
with 94 per cent, of aluminium is parallel to the aluminium line, but
higher up. Three per cent, of aluminium added to 97 per cent, of
copper yields an alloy with a resistance line parallel to that of

24& Professor Fleming [June 5,

copper, also higher up. When two pure metals are alloyed together
in various proportions there is generally some proportion in which
the resultant alloy has a maximum resistivity, and except in the case
of alloys of zinc, tin, lead and cadmium with each other, the resistivity
of the alloy is greater than that of either of its constituent metals.
In the case of many well-known alloys the proportions which give
high, if not the highest resistivity are those which correspond to
definite and possible chemical combinations of the metals with each
other, as, for instance, in the well-known platinum-silver alloy in
proportion 33 to 66, which corresponds in proportion with the com-
bination PtAg4 ; the iron-nickel alloy in proportion of 80 to 20, which
corresponds with the combination NiFe4 ; the platinum-iridium alloy
80 to 20, which corresponds with the combination IrPt4 ; and the
copper-manganese alloy 70 to 30, which corresponds with the com-
pound Cu^Mn; all of which are, as far as valency is concerned,
possible compounds. It is, however, found that very high resistivity
generally involves in alloys a want of tenacity and ductility, and
when we reach such limits as 100 microhms per cubic centimetre we
begin to find the solid alloys becoming less useful on account of this
deterioration of their useful mechanical quality.

We have especially studied the electrical resistance at low tem-
peratures of a large series of steel alloys containing varying propor-
tions of nickel, aluminium, chromium, tungsten and manganese in
them.

We have found that the electrical effect of adding to the iron the
other elements of the alloy is usually to shift up the resistance line
nearly parallel to itself, so that the resistance lines of all the iron
alloys are nearly parallel to that of the iron line, only the absolute
value of all the ordinates is increased. This is equivalent to saying
that the effect of the added material is to increase the specific resist-
ance, but not to alter the slope or form of the resistance curve.
Amongst these steel alloys there are two or three that are very inter-
esting. A nickel-steel alloy containing 19 per cent, of nickel, sent
to us by Mr. R. A. Hadfield, exhibits some very extraordinary proper-
ties. Nickel-steel alloys with large percentages of nickel can, as Dr.
Hopkinson has shown,* exist over wide limits of temperature in two
different physical states, in one of which they are strongly magnetic
and in the other of which they are feebly magnetic, and they
pass from the non-magnetic to the magnetic on cooling to low
temperatures. Here, for instance, is a sample of the 19 per cent,
nickel-steel in the non-magnetic condition. If it is cooled in liquid
air we can make it pass instantly into a magnetic condition. In the
first state it is fairly ductile and plastic, but in the second state it is
very hard and brittle. Moreover, its electrical resistance and thermo-
electric power are both permanently altered on undergoing this
change. In the non-magnetic state it has a high resistivity of about

* See Proc. Roy. Soc. 1890, vol. xlvii. p. 138.

H

H

H

1

■

^

H

1

H

H

^

1

H

H

H

1

■

H

B

'2

S3

i

1896.]

on Electric Research at Low Temperatures.

249

81,500 C.G.S. uuits per cubic centimetre at 0° C, but on cooling in
liquid air and becoming magnetic it is found to have decreased to
about 47,200 C.G.S. units when taken at 0° C. A very pretty way
of showing this difference in resistivity is to dip one half of a wire of
the 19 per cent, nickel-steel in liquid air, and then take it out, and
pass a strong electric current through the wire. The current raises
the half which has not been dipped into liquid air to a red heat
before the other half is visibly red hot.

It is, perhaps, more correct to say that this alloy can exist in an
infinity of different physical states, because we have found that the
lower it is cooled in temperature the lower its resistivity can be made

.v.^^^

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10

TENIPEF

ATURE

IN PLAl|lNUM D

CREES

-200- -150- -100-

-50^ -0^

Fig. 7

+ 50^ +100= +150-

Curve showing the Variation of resistivity of nickel-steel (19-64 percent, nickel)

when taken through a cycle of temperature from + 150° to -200°

and back again.

to be when measured again at ordinary temperatures. On heating up
the alloy again to a bright red heat it goes back into the non-magnetic
ductile state.

The chart (Fig. 7) before you shows the manner in which the
electrical resistance varies between the limits of —200° C. and 150° C.
when the alloy is taken through a cycle of temperature beginning at
150° C. in its non-magnetic state.

The 29 per cent, nickel-steel exhibits the same characteristics in
a less marked degree. A close study of this interesting material
shows that there is room for much valuable work upon it yet.

A manganese-steel, brought to notice by Mr. E. A. Hadfield,
having about 12 per cent, of manganese in it, is also capable of exist-
ing in two states, a magnetic and a practically non-magnetic variety.

250 Professor Fleming [Juno 5,

The magnetic variety, which is mucli more brittle, is, however, in
this case formed by the prolonged slow heating of the non-magnetic
variety out of contact with air. In the non-magnetic condition the
material has a rather high specific resistance at 0° C, about 65,700
C.G.S. units per cubic centimetre ; but the magnetic variety has a
much lower specific resistance, viz. about 51,400 C.G.S. units at 0° C

In all these cases it is interesting to note that the change of th
alloy into the magnetic variety is accompanied by a decrease in resi
tivity or increase in conductivity, and an increase in brittleness.

We have tried cooling this non-magnetic variety of manganese-
steel in liquid air, but have not been able in that way to make any
change in its condition as regards magnetic suscej)tibility.

There is a particular alloy, of copper 84 per cent., manganese 12
per cent., and nickel 4 per cent., called manganin, which at ordinary
temperature exhibits but little change of resistance with change of
temperature. On taking the curve of its resistance over wide ranges
of temperature we find that its curve is very concave downwards, and
the vertex of the curve lies at about 16° 0. Hence at ordinary tem-
peratures small changes of temperature make no change in its resis-
tance; but above that point its temperature coefficient is negative,
and below it it is positive. All alloys in which a negative tempera-
ture coefficient has been observed are probably instances of the
same mode of variation of resistance. It may be noted in passing
that the element manganese when present in an alloy seems to have
a great tendency to produce high resistivity and small temperature
coefficient.

Returning then to the pure metals, we may ask, What is the mean-
ing of the fact that in their case the resistance lines all converge
so as to indicate that the electrical resistance would vanish at the
absolute zero of temperature ?

We know that the passage, as we call it, of an electric current
through a conductor heats it, and that by Joule's law the rate of pro-
duction of heat in the conductor is proiDortional to the square of the
current' strength and to the total resistance of the conductor.

Suppose we take two wires, say of iron and a certain copper-
nickel-aluminium alloy having the same resistivity at 100° C. and of
the same size and length. These wires will at -j- 100° C. have the
same resistance. A given current flowing through them will therefore
generate heat in them both at the same rate.

Cool them both down, however, to the temperature of liquid air.
In the case of iron-wire the resistance is reduced to one-fifteenth of
its value at — 200° C, in the other case it is reduced by only 10 per
cent. Hence, at the low temperature the alloy dissipates energy for
the same current 13^^ times as rapidly as the pure metal.

It is a logical deduction from all we know to conclude that if we
could reach the absolute zero of temperature the j)ure metal would
not dissipate the energy of the current at all. Imagine two iron
wires, then, stretched through space, say from the earth to the moon,

1896.]

on Electric Besearch at Low Temperatures.

251

and kept everywhere at the absolute zero of temperature, we could
transmit any amount of electrical energy along them without dissi-
pating any of it as heat in the wires.

As a consequence of this, any pure metal cooled to the absolute
zero of temperature would become a perfect screen for electro-
magnetic radiation, and would be perfectly impenetrable to electro-
magnetic induction.

We can show this increase in the ^power of electro-magnetic

Fig. 8.

An alternating current magnet having a coil C between its poles over which a
shield A of aluminium can be placed.

screening by metals when cooled in the following way. A suitable
coil of wire C is placed (see Fig. 8) between the poles of an alternating
current magnet M, M and a small incandescent lamp L connected with
the coil. When the magnet is excited it induces currents in the coil
and the lamp glows up. A cap of aluminium A is made of such a
size as to drop easily over the coil. This aluminium is not of
sufficient thickness or conductivity to screen oft' the induction when it
is warm. If, however, we cool the aluminium caj) in liquid air and

252 Professor Fleming [June 5,

then drop it over the coil the lamp for one instant goes out, but it
brightens up again as the metal cap instantly warms up. This
shows us, however, that if the cap were at the absolute zero of
temperature it would then be a complete screen for the induction.
In fact, these experiments furnish us with a new definition of what
we mean by the absolute zero of temperature. It is the tempera-
ture at which perfectly pure metals cease to have any electrical
resistance.

In the conduction of currents at ordinary temperatures as we
generally know it, two effects are inseparably connected with the
conveyance of energy by this process. One is the dissipation of some
of the energy as heat in the conductor, the other is a loss of potential
or fall of electric pressure, the latter being one of the factors in the
equivalent of the energy so dissipated. If, however, the conductor is
at the absolute zero of temperature, there would be no heat produced
in it, and no fall of potential along it, either for large or small
currents. What then under these conditions is the function of the
conductor ? The answer is, that it becomes a mere boundary serving
to limit the electro-magnetic field and determine the direction in
which the energy transmission is taking place. These experiments
therefore may be regarded as forging one more important link in that
chain of experimental evidence which compels us to look for the
processes concerned in the conveyance of energy by an electric
current, not inside the conductor as we call it, but in the dielectric
or medium outside. We may then ask. How is it that different bodies
have such various dissipative powers when acting in this way as the
boundary of an electro-magnetic field ? The only suggestion on this
point I venture to make here is as follows : — Materials of high
specific resistance have all probably a very complex molecular struc-
ture. The alloys of high resistivity are probably not merely soli-
dified mechanical mixtures of metals, but chemical compounds, and
even in the case of elementary bodies like carbon and sulphur, which
have high resistivity, these last-named bodies may have, owing to
their high valency and tendency of their atoms to auto-combination,
a complex molecular structure.

This structure may bestow upon them the power of taking up
energy from the electro-magnetic medium, just as gases with a highly
complex molecular structure are very absorbent of radiant heat, which,
if the electro-magnetic theory of light is true, is only another form
of electro-magnetic energy. All we know at present about the pro-
cesses at work during the time a conductor is traversed by an electric
current, is that there is a magnetic field outside the conductor and
also within the mass of the conductor, and that some mechanism is at
work absorbing energy through the surface of the conductor and
dissipating it as heat in the interior. The resistance of a conductor
is best defined as, and numerically measured by, the number express-
ing the rate at which it dissij)ates electro-magnetic energy per unit
of current. For the same current, that is for the same external

1896.]

on Electric BesearcJi at Low Temperatures.

253

magnetic field, conductors dissipate this energy at very different
rates. Some, like silver and copper, whicli have the lowest rates,
are elements of low valency and relatively small molecular volume,
and have probably a simple molecular structure ; others, like alloys
of high resistivity, have in all probability a more complex molecular
structure. Both this last, as well as the molecular mobility charac-

100. 000

-200?

-100?

0-

+ 100-

9U.000

TEMPE

RATURE

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.^

80.000 Ji

I

70.000 ,;

s

i

STANCE IN

so.ooo w

VOLUME SI

30.000

20.000

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^^

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Fig, 9.
Resistivity curve of mercury in terms of platinum temperature.

teristic of the liquid state, are conditions which bestow the power of
taking up rapidly and dissipating the energy of the electro-magnetic
field, and this energy has to be kept supplied from external energy-
transforming sources. We cannot, however, at present profitably
construct further mechanical hypotheses to account for this difference
between conductors, in the presence of our great ignorance about
ether, molecules and energy.

In passing from the liquid to the solid state there is generally an
immense increase in the conducting power of metals. This is well

254

Professor Fleming

[June 5,

shown in the case of mercury. A glass tube a metre in length was
formed into a spiral coil and filled with pure mercury, suitable con-
nections being provided at the ends. This coil was imbedded in a
mass of paraffin wax, and a platinum wire thermometer placed in
contact with it. The whole mass was then reduced to the tempera-
ture of liquid air, and observations taken of the resistance of the
mercury as it heated slowly up after being removed from the liquid
air. The curve in Fig. 9 shows the manner in which the resistance
increases with great suddenness between —41° and —36° as the metal
passes into the liquid condition. The resistance becomes four times
greater between — 50° and — 36° in the course of 14° rise of
temperature, and whilst in the act of passing through the melting

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TEMPERATURE

55

-200

100^

-100 O"

Fig. 10.
Eesistivity curves of bismutli in terms of platinum temperature.

point of the mercury at — 38° '8 C. This chart shows that the resist-
ance curve of the mercury in the solid state tends downwards, so as
to indicate that its resistivity would completely vanish exactly at the
absolute zero of temperature. It is interesting to note also that the
portion of the resistance curve belonging to mercury in the solid
state is sensibly parallel to that portion of it in the liquid state.

We carried on a long struggle with bismuth in the endeavour to
unravel some of the electrical peculiarities of that metal at low tem-
peratures. Chemists are aware of the extreme difficulty of preparing
bismuth in a state of perfect chemical purity by purely chemical
means. From several different sources we procured bismuth which
had been carefully prepared by the reduction of the oxychloride or
nitrate after careful re-precipitations. This bismuth was then pressed
into wire, and its resistance curves taken down to the lowest attainable

1896.] on Electric Research at Low Temperatures. 255

temperatures. We found some very extraordinary results. Although
sensibly agreeing in resistivity at ordinary temperatures, in two cases
(see Fig. 10) the resistance curves had a minimum j)oint, and after
reaching this at about — 80^ tended upwards again; thus showing
that the resistance was increasing as the metal was further cooled.
These curves could be repeated as often as necessary with these
samples. Another specimen gave a curve with a double bend (see
Fig. 10). These results convinced us that it would be necessary to
prepare bismuth electrolytically, and with the assistance of Messrs.
Hartmann and Braun, of Frankfort, who have made a special study
of the preparation of electrolytic bismuth, we were provided with a
quantity of the metal which examination showed to be chemically
pure. On taking the resistance curve of a sam23le of this electro-
lytic bismuth when pressed into uniform wire under great pressure,
we found that its behaviour was perfectly normal, and that the resist-
ance line tended downwards, as in the case of all other pure metals, to
the absolute zero. Also we found that the specific resistance of
this last is very much less than that of the chemically prepared
samples, and less even than that employed by Matthiessen. Hence
pure bismuth is no exception to the law enunciated above. Bismuth
is characterised especially by many peculiarities. It has been known
for some time that the resistance of a bismuth wire is increased when
it is placed in a magnetic field, so that the lines of the field are
perpendicular to the direction of the current flow. This is easily
shown by means of one of Hartmann and Braun's spirals, manu-
factured now purposely for measuring magnetic fields.

We have, however, discovered that if bismuth is cooled to the
temperature of liquid air the effect of any given magnetic field in
changing its resistance is increased many times. Thus, for example :
A certain bismuth wire we used had a resistance of 1 • 690 ohms at
20° C. Placed in a magnetic field of strength 2750 C.G.S. imits so
that the wire was transverse to the direction of the field, its resist-
ance was increased to 1*792 ohms, or by six per cent. The wire was
then cooled in liquid air and its resistance lowered to 0 • 572 ohms.
On putting it then into the magnetic field of strength 2750 C.G.S.
units its resistance became 2*68 ohms. Hence it had increased 368
per cent. This magnetic field can thus actually reverse the effect of
the cooling, and cause the bismuth, when cooled and magnetised, to
have a greater resistance than when at ordinary temperatures and
unmagnetised. We are at present engaged in further unravelling the
problems presented by this new discovery with regard to bismuth.*
It is certainly very startling to find that a magnetic field which in-
creases the resistance only 5 per cent, at ordinary temperatures increases
it five times at — 186° C. We have recently discovered a similar,

* Since the delivery of this discourse we have been able, by the employ-
ment of a powerful electro-magnet kindly lent to us by Sir David Salomons, to
increase the resistance of bismuth, when cooled in liquid air, more than 150 times,
by magnetising it transversely in a field of 22,000 C.G.S. units.

256 Professor Fleming [June 5,

but mucli smaller effect in the case of nickel longitudinally mag-
netised. It will be seen that this process of taking the resistance of
a conductor in liquid air is one which affords us a very critical means
of discrimination as to the chemical purity of a metal. It ranks
almost with the spectrosco23e as an analytical method. There is one
other method by which we can exhibit the change in conductivity in a
metal when cooled, and that is by the increased deflection which a
disc of the metal experiences when suspended in an alternating
current field in such a position that the plane of the disc is at an
angle of 45^ to the direction of the field.

Time will only permit one brief reference to the behaviour of
carbon in regard to electrical conductivity when cooled to low tem-
peratures. We have found that carbon in the form of carbon fila-
ments taken from various incandescent lamps continued to increase
in resistance as it was lowered in temperature. The resistivity at
various temperatures of the carbon from an Edison-Swan lamp is as
follows : —

C.G.S. Units.

Temp. C.

3835 X 103 at

99°

3911 X 10^ at

18° -9

3953 X 103 jjt

1°

4054 X 103 at

- 78°

4079 X 103 ^t

- 100°

4180 X 103 at

-182°

These values, when represented on a chart, give almost a straight
line, and show that the resistivity of carbon continually increases
as it is cooled, but at a very slow rate. Its temperature coefiicient is
therefore negative, and of about the same absolute magnitude as many
alloys of high resistivity. The resistivity of this form of carbon is
about three thousand times that of silver. Adamantine carbon taken
from a Woodhouse and Eawson lamp had ,a resistivity 60 per cent,
greater.

All the so-called insulators — e. g. glass, gutta-percha, ebonite,
paraffin — have resistivities enormously greater than that of carbon,
but like it, their resistance increases as the temperature is lowered.
For the sake of comparison we have placed upon this chart of lines
of metallic resistivity (referring to the large diagram used at the
lecture) the resistance line of carbon with ordinates drawn
to a scale of one-hundredth part of those of the metals. To
properly represent to the full scale the line of carbon, this chart,
which is 15 feet long, would have to be made one-third of a mile
long. If we desired to represent on the same scale the resistivity of
gutta-percha, the length of the chart would have to be billions of
miles — in fact, so long that light would take 5000 years to traverse
it from one end to the other ; even then, to represent to the same
scale the resistance lines of paraffin and ebonite, it would have to be
thirty or forty times longer.*

We must next pass on to consider some problems in thermo-

* The resistivities of platinoid, carbon, and gutta-percha at 0° C. are nearly
in the ratio of the numbers 4 x 10^ 4 x 10^ and 4 x 10^3^

1896.]

on Electric Research at Low Temperatures.

257

electricity which have engaged our attention. If we construct a
thermo-electric couple of two metals and connect this with a
galvanometer, and if one junction is kept at a constant temperature,
say 0° C, whilst the other junction is heated or cooled to various
temperatures, we shall in general, but not always, find an electro-
motive force acting in this circuit when the junctions are at different
temperatures. This electromotive force depends on three things —
the nature of the metals, the temperatures of the junctions, and on
a certain temperature called the neutral temperature of the metals. An
important matter in the experimental study of thermo-electric action
is to discover the position of these neutral temperatures, when different
metals are tested with lead as the standard of comparison, and when
one junction is kept at 0° C. Elaborate experiments made by
Professor Tait many years ago furnished full information on this
matter for temperatures lying above 0° C, and we especially desired
to extend this knowledge to ranges of temperature between 0°,O. and
— 200° C. Accordingly, a number of thermo-electric junctions were
prepared of various pure metals and alloys, the comparison metal

Fig. 11.
Potentiometer arrangement for measuring thermo-electromotive forces.

being always pure lead. These couples were grouped together, and
one set of junctions always kept at 0° C. in melting ice. The other
set of junctions was cooled to various low temperatures by means of
liquid air. The experimental process then consisted in measuring
the electromotive force set up in each couple respectively, and at
the same instant measuring the temperature of the low temperature
junction. After various failures a device was adopted for making this
double measurement with great accuracy and expedition.

The arrangement consisted of a combined potentiometer and re-
sistance balance (see Fig. 11). A long uniform wire stretched over
a scale had a battery connected to its two ends so as to make a fall of
potential down the wire which could be regulated by appropriate
resistances. It will be easily seen that we can combine a galvano-
meter and resistance coil with this arrangement in such a manner as
to form it into a Wheatstone's bridge or a potentiometer. In this
latter form of instrument an unknown electromotive force is balanced

Vol. XV. (No. 90.) s

258

Professor Fleming

[June 6,

against the known fall of potential down a certain length of a gra-
duated wire, and a galvanometer employed to ascertain the point on
the slide wire at which this is the case. Omitting details, it may be
stated that I succeeded in devising an arrangement of circuits in which
this change from a potentiometer to a resistance bridge was e£fected by
moving two brass plugs from one pair of holes to another. This in-
strument formed a most useful combined resistance and electromotive
force measurer which enabled us to do two things — first, to measure
the electromotive force in any thermo couple ; secondly, to measure
the temperature of the low temperature junction by measuring the
resistance of a platinum wire wound round that junction and acting
as a thermometer. In actual practice the platinum thermometer
consisted of a small hollow copper cylinder, in the interior of this
cylinder being inserted a number of the thermo junctions, and round
the outside of which the platinum thermometer wire was wound. Aided

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Fig. 12.

Curve of thermo-electromotive force of a platinum-lead couple at various tem-
peratures ; one junction kept at 0° C, the temperature of the other being varied.
The sloping dotted line represents the variation of the thermo-electric power of
platinum with respect to lead.

by this device we were able to measure temperatures with an accuracy
of ^1^ of a degree at a temperature of —200° C, and to ascertain at
the same instant the exact electromotive force acting in the couple.
When these arrangements had been perfected the method adopted
was to put one set of the junctions in melting ice. The other set,
enclosed in the copper cylinder, were imbedded in a mass of paraffin
wax, which was then cooled down to the temperature of liquid air.
The mass was then removed and inserted in a vacuum vessel, and
allowed to heat up very slowly. At frequent intervals during the
heating the electromotive force of the couple was taken, and also the
temperature of the junction.*

The events which under such conditions happen in the case of a
platinum-lead junction can easily be shown and are very interesting
(see Fig. 12). At the first immersion of one junction in liquid air,
whilst the other is in melting ice, we get a current as shown by the

* For fuller information see Dewar and Fleming on the ' Thermo-Electric
Powers of Metals and Alloys,' ' Philosophical Magazine,' July 1895.

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1896.

on Electric Besearch at Low Temperatures.

259

galvanometer in one direction. On lifting one junction out of the
liquid air it begins to warm up. The first effect of this heating is
to reduce the thermo current in the circuit. At about — 111° on our
platinum scale, some distance therefore above that of liquid air, the
current in the circuit falls to zero. As the junction continues to heat

Temperature.

-200

up, the current increases again in
the opposite direction. At about
— 60" the low temperature junc-
tion reaches the temperature
called the neutral temperature,
and the current is a maximum
in one direction. It then begins
to fall off once more, and finally
becomes zero again when the two
junctions are both at the tem-
perature of melting ice, and it
lastly increases in the opposite
direction as this variable junction
continues to warm up from 0° C.
to higher temperatures.

Having carried out the obser-
vations described with all our
thermo couples, the results were
represented on a chart (see Fig.
13) as follows: — A horizontal
line was taken on which were
marked off divisions representing
platinum temperatures. Vertical
ordinates were then drawn at
various temperatures for each
couple, representing the electro-
motive force in this couple when
the cold junction was at the tem-
perature denoted by the abscissa
of that ordinate. In this way a
series of curves were delineated
which all passed through the
point representing 0° C. These
curves are the curves of thermo-
electromotive force.

In Professor Tait's researches
on this subject he adopted a
method of representing the facts
which has many advantages. Suppose the couple to have one
junction at a constant temperature and the other to be vary-
ing. At any instant the electromotive force of the couple is
varying at a certain rate with the changing temperature of the
non-constant junction. This rate measures what is called the

s 2

Fig. 14.

Curves showing the variation with tem-
perature of the thermo-electric power
of various metals. The thermo-elec-
tric lino of lead being represented
by the dotted line.

260 Professor Fleming [June 5,

thermo-electric power of the metals with respect to each other at
that temperature. If we measure the slope of the electromotive
force curve at any point, it can easily be shown that the numeri-
cal value of this slope gives us the rate of change of electro-
motive force with temperature. If we plot these slopes in terms of
the corresponding temperature, we obtain another set of curves called
curves of thermo-electric power. Lead is always taken as the stan-
dard metal for comparison, because the Thomson effect in lead is zero.
From our chart of thermo-electromotive forces we have constructed
another one of thermo-electric powers (see Fig. 14). The lines of
thermo-electric power cut the lead line in various places, and the
temperature at which they do this is called the neutral temperature
of that metal with respect to lead. Professor Tait deduced from his
experiments that these thermo-electric lines were straight lines for
temperatures above zero Centigrade, and he made, in addition, the
important discovery that for certain metals such as iron and nickel
the thermo-electric lines have sudden changes of direction at high
temperatures.

The general result of our investigations at low temperatures is to
show that, whilst in some cases the thermo-electric lines, as may be
seen from the diagram in Fig. 14, are approximately straight lines
for temperatures down to the lowest reached, they are not all by
any means straight lines. In some cases, such as iron and bismuth,
we find sudden changes of direction of the thermo-electric lines
similar to those found by Professor Tait at higher temperatures,
and this indicates a change in sign in the Thomson effect at that
point. Moreover, in many cases there is a decided tendency of the
lines of many metals to bend round in a manner which indicates
that their thermo-electric power probably would become zero at the
absolute zero of temperature.

The temperature at which the thermo-electric line of any metal
crosses the line of lead gives us the neutral temperature of that metal
with respect to lead, and at that temperature the metal is thermo-
electrically identical with lead. If one junction of a couple is at a
temperature as far above the neutral temperature of the metals as
the other is below it, the couple will give no electromotive force.
This provides us with an experimental method of determining the
position of certain neutral points. Thus, for instance, if one
junction of a platinum-zinc couple is placed in liquid air and the
other is raised to above 30° we get no electromotive force from that
couple. This indicates that the neutral temperature of platinum and
zinc is about — 85'', and this is shown to be the case from the chart.
Two general conclusions are arrived at from a study of the thermo-
electric lines as laid down in our chart. The first of these is that
the thermo-electric lines of many metals are by no means straight
lines over extreme ranges of temperature. Hence the thermo-electric
power is not simply a linear function of the absolute temperature.
The second important fact is, that in the thermo-electric lines of

1896.] on Electric Besearch at Low Temperatures, 261

certain metals at low temperatures there are sudden changes of
direction which indicate a change in the sign of the Thomson effect
in that metal at that temperature, and probably, therefore, some
important molecular change at the corresponding temperature.

In the case of the 19 and 29 per cent, nickel-steel alloys there is
an interesting thermo-electric phenomenon. If a loop of wire of this
material is partly dipped in liquid air, the portion cooled becomes
thermo-electrically dififerent from the remainder, and gives a strong
thermo current if connected to a galvanometer and warmed at one
point, where the changed and unchanged portions meet.

Leaving the further elaboration of these points, we must next
notice some of the facts with respect to the magnetisation of iron at
low temperatures. Professor Dewar mentioned, in a discourse on the
scientific uses of liquid air, some results obtained on cooling small
steel magnets. These effects we have since again explored at greater
length.

Let me show you, in the first place, the effect of cooling a small
steel permanent magnet to the temperature of liquid air. We will
first take a magnet made of a fragment of knitting needle or ordinary
carbon steel and examine the effect of low temperature upon it.
Placing the magnet behind the small suspended magnetic needle of a
magnetometer we obtain a deflection of the magnetometer needle,
which is a measure of the magnetisation of the magnet causing the
deflection. On bringing up a small vessel of liquid air and immers-
ing in it the magnet under test we notice at once a sudden decrease
in the deflection of the magnetometer needle. This indicates that a
notable percentage of the magnetisation of the magnet has been
removed. On taking away the liquid air bath and allowing the magnet
to heat up again we find that there is a still further decrease in mag-
netisation. On cooling it again with liquid air the magnetisation
then increases, and from and after that time the effect of the cooling is
always to increase the moment of the magnet, and the effect of heat-
ing it up again always to decrease the moment of the magnet. Hence
we see that the effect of the first immersion in liquid air is to give
a shock to the magnet which deprives it permanently of a consider-
able percentage of its magnetism ; but when once it has survived this
treatment, then cooling it strengthens the magnet, and warming it
weakens it.

This is not by any means always the case. If we take a magnet
made of the 19 per cent, nickel-steel, the peculiar characters of which
were explained a few moments ago, we shall find a very different
state of affairs. Here we see the first effect is, as before, to remove
a very considerable percentage of the initial magnetisation ; but after
that stage is passed, then cooling this nickel-steel magnet always
weakens it still more, and warming it up again strengthens it. The
subsequent effect of cooling is therefore in the opposite direction in
the carbon-steel and in this nickel-steel. These changes of moment
can best be represented by a diagram of lines as in Fig. 15.

262

Professor Fleming

[June 5,

We Lave in this way examined the behaviour of magnets made
of a very large number of steels — chromium-steels, aluminium-steels,
tungsten-steels, silicon-steels and nickel-steels, in various states of
temper, hard and soft. We find that in some cases there is no initial
decrease of magnetism at all, and that the steady state begins at
once. Broadly, however, the results amount to this : — A steel magnet
when plunged into liquid air generally loses some fraction of its
magnetisation, but that after a few such immersions it arrives at
a fixed condition in which the effect of cooling it is in most cases to
produce an increase of magnetic moment, but in a few exceptional
cases to produce a decrease of magnetic moment. In the case of the
nickel-steels we have found very curious changes of magnetic

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Fig. 15.

19 % Nichel Steel.

Diagram showing changes of magnetic moment of a magnet when alter-
nately cooled in liquid air and warmed up again to -|-5° C. The length of the
firm lines represents the value of the magnetic moment when cooled, and that of
tlie dotted when warm.

moment as the magnet is heated up from — 186° C. to -f 300°. There
is a maximum magnetic moment at about 40° C. (see Fig. 16) in the
case of the 19 per cent, nickel-steel.

In the technical use of magnets for instrumental purposes they
have to go through a process called ageing to get rid of the sub-
permanent magnetism. One of the best ways of ageing a magnet is
to plunge it several times into liquid air.

We have given a large amount of attention to a study of the
changes taking place in the magnetic qualities of soft or annealed,
and also in hard iron when cooled to very low temperatures.

In the first place, we have examined the change in the permea-
bility of iron at the temperature of liquid air. If a ring of iron
is wound over with a coil of wire and subjected to gradually in-

1896.]

on Electric Besearch at Low Temperatures.

263

creasing magnetising forces, this force produces magnetisation in the
iron, but the magnetisation does not increase proportionally with the
force. It tends to a limit, and the curve which shows this variation
is called a magnetisation curve. The number which expresses the
ratio of the magnetisation to the magnetising force is called the
susceptibility of the iron. Instead of considering the magnetisation
of the iron as one of the variables, it is often convenient to con-
sider the induction in the iron, and the induction is defined as a
quantity, the rate of change of which with time measures the electro-
motive force set up in a secondary circuit wound round the iron ring.

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Fig. 16.

The ratio between the induction and the magnetising force at any
instant is called the permeability of the iron. By tedious experiments
with the ballistic galvanometer, it is possible to draw out a complete
magnetisation curve of the iron, starting from the lowest induction
up to the point at which the iron becomes practically saturated.
Assisted by Mr. J. E. Petavel, who has given us most valuable help in
these very tedious magnetic observations, as well as in the subsequent
reductions of them, a large number of observations have been made
on the permeability of a carefully annealed iron ring made of very
fine Swedish iron of the highest quality.* The result is to show —

* It is only right to add that in other portions of this work, especially in
the resistance and thermo-electric work, we have been much indebted for careful
and persevering assistance to Messrs. J. and D. Morris and, in lesser degree, to
Messrs. Jakeman and Tilney for help in other observations requiring severa]
simultaneous observers.

264

Professor Fleming

[June 5,

as seen from the curve (see Fig. 17) — that cooling the iron to — 186° C.
slightly diminishes the permeability. In other words, it requires
a greater magnetic force to produce a given amount of magnet-
isation when the iron is at — 186° C. than when it is at the ordinary
temperature.

When, however, we began to study the behaviour of hardened
iron in this respect, we found ourselves in the presence of very

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Magnetisation and permeability curves of soft iron at 20° C. and - 186° C.

curious effects. If pure iron, which has been carefully annealed, is
twisted, knocked, bent, stretched, or compressed, it passes into a state
known as hard iron, and hard iron has very different magnetic
qualities from soft iron. A very extended series of experiments
with rings of hard iron have shown that hard iron, at least in certain
cases, has its permeability greatly increased by cooling, and this
change takes place with great suddenness. We can show you by a
simple experiment that this is the case. If we take this hard iron

1896.]

on Electric Besearch at Low Temperatures.

265

ring, which has two coils of wire wound round it, and connect one of
these circuits to a battery, we shall send a current through this
primary coil and magnetise the iron ring. If the other, or secondary
circuit is connected to a galvanometer, then at the instant of starting
the primary current there is a transitory induced current produced
in the secondary circuit. As long as the induction in the iron
remains constant no electric change will take place in this secondary
circuit. If, however, we plunge the
iron ring into liquid air, whilst
still keeping the primary current
constant, we find again a secon-
dary current produced at the
moment of cooling the iron.
This indicates a sudden increase
of permeability at the instant of
cooling. If we bring the ring
out of the liquid air we find it
retains some of the increased
permeability acquired on cooling,
but loses a portion of it more
slowly if it is heated up again
to ordinary temperatures by
plunging it into a bath of alco-
hol. Owing to these changes
we found it impossible to repeat
again exactly any required mag-
netisation curve in the case of
the hard iron. The sudden cool-
ing alters the magnetic qualities
of the unannealed iron to such
an extent that it is not possible
to get it twice in exactly the
same state.

By subjecting a hard iron
ring to frequent reversals of the
same magnetising force, whilst it
is warmed up slowly from the
temperature of liquid air up to
ordinary temperatures, we have
been able to trace the gradual
decrease of the permeability at
any constant force throughout this range of temperature, and the
results are embodied in the series of curves in Fig. 18.

We have found, on the other hand, that unhardened steel pianoforte
wire behaves like soft annealed iron.

We have then examined the hysteresis of iron at low temperatures.
As the meaning of that term was very fully explained by the inventor
of it in a discourse given quite recently, no time need be spent in an

TEMPERATURE IN PLATINUM DEGREES.
-200° -150° -100° -50° 0°

Fig. 18.

Curves showing the variation of per-
meability of iron with temperature
between 0° C. and -200° C.

266

Professor Fleming

[June 5,

elaborate explanation of it. It is sufficient to say that when iron is
magnetised and demagnetised, or carried round a cycle of magnetisa-
tion in which its direction of magnetisation is first in one direction
and then in the other, this process involves the expenditure of energy,
and such dissipation of energy is spoken of as the hysteresis loss in
iron. It would occupy too much time to attempt to explain in full
detail the manner in which this dissipated energy can be measured.
As a matter of fact, the method we adopted was the laborious but
exact one of delineating a complete magnetisation curve of the iron,
by means of observations taken with the ballistic galvanometer for
various maximum values of the magnetising force. In this way we
were able finally to arrive at a curve which represented by its ordi-
nates the value of the hysteresis loss in the iron in ergs per cubic

2000 4000 6000 8000 10.000 I2.00P

maximum induction during cycle.

Fig. 19.
Yariation of hysteresis loss in soft iron with temperature.

centimetre per cycle, and the abscissae the maximum value of the cor-
responding magnetic induction. AYhen curves had been drawn out
(see Fig. 19) from all the many hundreds of observations for the case
of the same soft iron ring at ordinary temperatures and at the tem-
perature of liquid air, we found little or no sensible difference
between them. The result is, then, that there is no appreciable
change in the magnetic hysteresis loss of very carefully annealed soft
Swedish iron when cooled to these low temperatures.* With regard
to the hard iron, although the permeability is increased, it is most
difficult to say yet whether the hysteresis is increased or not, as
every fresh reduction in temperature of the iron alters its physical

* The iron used iu all these experiments was a sample of Sankey's trans-
former iron, kindly sent to us by Mr. R. Jenkins.

1896.] on Electric Besearch at Low Temperatures. 267

state, and makes it almost impossible to obtain similar repeated
measurements.

It is natural to inquire how far accepted theories of magnetic
action are able to reconcile the above-mentioned results. Some of
them undoubtedly are in accord with deductions from received
hypotheses. It is generally considered that the facts connected with
the magnetisation of iron indicate that each molecule, or perhaps
small groups of molecules, of the iron are complete micro-magnets,
and that in the unmagnetised condition of the iron these molecular
magnets arrange themselves in groups or in closed circuits so that
for each little group the external magnetic action or magnetic moment
is approximately zero. Magnetisation consists in arranging the
members of some or all of these groups so as to co-lineate the direction
of more or less of the molecular magnets and produce an external
resultant magnetic moment.

Let us then consider one such little group by the aid of a model
made of small magnets, such as Ewing has suggested and used.

SujDpose the members of this group to be at a certain distance
from each other, and we apply a given magnetising force which is
just sufficient to open out the group and co-lineate the magnetic
axes of the several members of it.

Next, suppose we cool this iron, this would result in bringing
the members of the group into closer contiguity. The result of this
will be an increase of the interpolar magnetic forces of the different
members of the group ; and as we can see from the behaviour of the
model, it would require a greater magnetic force to effect the same
amount of co-lineation of the molecular magnets. This, therefore,
corresponds with what we find to be the case on cooling soft iron to
very low temperatures. Professor Dewar's experiments have shown
that the tensile strength of iron and steel is increased to about
double on cooling to — 182° C, and it is quite reasonable to suppose
that this is the result, in part at least, due to an approximation of the
molecules.

As regards the behaviour of magnetised steel and iron when cooled,
it is highly likely, when the groups of molecular magnets have been
opened out more or less, that some of these are in a condition of insta-
bility, in which bringing the members of the group nearer together will
have the effect of making them close up again into magnetic circuits
of no external action. Hence, if this is the case, the first effect of the
sudden cooling will be to effect the observed change. These half-
hearted groups of molecular magnets constitute the subpermanent
magnetism which it is our desire to get rid of in ageing a magnet.
Then, as regards the effect of temperature changes on the magnet
when the stable condition of affairs is reached. In order to explain
this, I think we must consider the action of the molecular groups
upon each other. The approximation of molecular groups will in
general, after the magnet is aged, have the effect of co-lineating more
completely the different members of the groups, and hence increase

268 Professor Fleming on Electric Research. [June 5,

the magnetic moment of the magnet, whilst the separation of the
molecular groups and the reverse effects ensue on heating. The
action of the low temperature upon soft iron and upon magnetised
steel would be explicable then if we may legitimately make the
assumption that lowering the temperature approximates the molecular
groups and also the members of each group.

The result of this, in the case of existing permanent magneti-
sation, is to close up more or less those groups which are in an
unstable condition, but to increase the co-lineation in those groups
in which the magnetic moment exceeds a certain value. Hence, in
the case of the permanent magnet, the first effect of sudden cooling is
a compound effect ; it consists in a great reduction of the magnetic
moment of certain unstable groups, but in an increase of moment of
others. After this initial stage is past, the normal effect is an
increase of magnetic moment of the groups by bringing the members
of them closer together, and a diminution by increase of distance.
There remains then to be explained the anomalous behaviour of the
nickel-steel and hardened iron, but an attempt to throw an inner
light upon the results obtained with these substances cannot possibly
be successful until we have explored far more thoroughly, at low
temperatures, the changes in mechanical as well as magnetic
qualities.

Much as we may be tempted to speculate upon the causes of
these various changes in the properties of matter at very low tem-
peratures, a more important duty at the present time is the collection
of facts and the completion of accurate quantitative measurements.
The experimental difficulties of this low temperature research are
very great, but both Professor Dewar and I have been chiefly anxious
in this particular work to prosecute preliminary explorations in
as many regions of it as possible, these pioneering experiments
enabling us to ascertain in what direction further inquiry will be
profitable. Every step forward opens up fresh suggestions for
investigation, and, I may add, fresh difficulties. In the light of the
results, however, thus ascertained, we shall have additional means
of testing and judging existing electrical theories, and the facts
themselves, when built into the fabric of scientific knowledge, will
serve to broaden those foundations on which we may profitably erect
new hypotheses of electric and magnetic phenomena, which, even if
they can do but little to dissipate that mystery which enshrouds the
most familiar facts, will serve as a continual stimulus to thought and
work in days and years that are yet to come.

f J. A. F.]

1896.] Mr. Thomas Martin on the Utilisation of Niagara. 269

EXTRA EVENING MEETING,

Friday, June 19, 1896.

The Rt. Hon. Lord Kelvin, D.C.L. LL.D. F.R.S. Vice-President,

in the Chair.

Thomas Commerford Martin, Esq. (of New York), American
Delegate to the Kelvin Celebration.

TJie Utilisation of Niagara.

The broad idea of the utilisation of Niagara is by no means new, for
even as early as 1725, while the thick woods of pine and oak were
still haunted by the stealthy redskin, a miniature saw-mill was set
up amid the roaring waters. The first systematic effort to harness
Niagara was not made until nearly 150 years later, when the present
hydraulic canal was dug and the mills were set up which disfigure
the banks just below the stately Falls. It was long obvious that even
an enormous extension of this surface canal system would not answer
for the proper utilisation of the illimitable energy contained in a vast
stream of such lofty fall as that of Niagara.

Niagara is the point at which are discharged, through two
narrowing precipitous channels only 8800 feet wide and 160 feet
high, the contents of 6000 cubic miles of water, with a reservoir area
of 90,000 square miles, draining 300,000 square miles of territory.
The ordinary overspill of this Atlantic set on edge has been deter-
mined to be equal to about 275,000 cubic feet per second, and the
quantity passing is estimated as high as 100,000,000 tons of water
per hour.

The drifting of a ship over the Horse Shoe Fall has proved it to
have a thickness at the centre of the crescent of over 16 feet. Between
Lake Erie and Lake Ontario there is a total difference of level of
800 feet (Fig. 1), and the amount of power represented by the water at
the Falls has been estimated on different bases from 6,750,000 horse-
power up to not less than 16,800,000 horse-power, the latter being a
rough calculation of Sir William Siemens, who, in 1877, was the first
to suggest the use of electricity as the modern and feasible agent of
converting into useful power some of this majestic but squandered
energy.

It may be noted that the water passing out at Niagara is wonder-
fully pure and " soft," contrasting strongly, therefore, with the other
body of water, turbid and gritty, that flows from the north out through
the banks of the Mississippi. The annual recession of the American

270

Mr. Thomas Commerford Martin

[Jnne 19,

Fall, of 74 inches, and of

the Horse Shoe, of 2 • 18 feet, would probably
have been much greater
had the water been less
limpid.

TheroaroftheFalls,
which can be heard for
many miles, has a deep
note, four octaves lower
than the scale of the or-
dinary piano. The fall
of such an immense body
of water causes a very
perceptible tremor of the
ground throughout the
vicinity. The existence
of the Falls is also in-
dicated by huge clouds
of mist which, rising
above the rainbows,
tower sometimes a mile
in air before breaking
away.

It was Mr. Thomas
Evershed, an American
civil engineer, who un-
folded the plan of divert-
ing part of the stream at
a considerable distance
above the Falls, so that
no natural beauty would
be interfered with, while
an enormous amount of
power would be obtained
with a very slight reduc-
tion in the volume of
the stream at the crest
of the Falls. Essenti-
ally scientific and cor-
rect as the plan now
shows itself to be, it
found prompt criticism
and condemnation, but
not less quickly did
it rally the able and
influential support of
Messrs. W. B. Rankin e,
Francis Lynde Stetson,
Edward A. Wickes, and

1896.] on the Utilisation of Niagara. 271

Edward D. Adams, who organised the corporate interests that, with
an expenditure of 1,000,000Z. in five years, have carried out the
present work.

So many engineering problems arose early in the enterprise, that
after the survey of the property in 1890, an International Niagara
Commission was established in London, with power to investigate
the best existing methods of power development and transmission, and
to select from among them, as well as to award prizes of an aggre-
gate of 4400J. This body included men like Lord Kelvin, Mascart,
Coleman Sellers, Turrettini and Dr. Unwin, and its work was of the
utmost value. Besides this the Niagara Co. and the allied Cataract
Construction Co. enjoyed the direct aid of other experts, such as
Prof. George Forbes, in a consultative capacity ; while it was a
necessary consequence that the manufacturers of the apparatus to be
used threw upon their work the highest inventive and constructive
talent at their command.

The time-honoured plan in water-power utilisation has been to
string factories along a canal of considerable length, with but a short
tail race. At Niagara the plan now brought under notice is that of
a short canal with a very long tail race. The use of electricity for
distributing the power allows the factories to be placed away from
the canal, and in any location that may appear specially desirable or
advantageous.

The perfected and concentrated Evershed scheme comprises a
short surface canal 250 feet wide at its mouth, 1^ mile above the
Falls, far beyond the outlying Three Sisters Islands, with an intake
inclined obliquely to the Niagara Kiver. This canal extends inwardly
1700 feet, and has an average depth of some 12 feet, thus holding
water adequate to the development of about 100,000 horse-power.
The mouth of the canal is 600 feet from the shore line proper, and
considerable work was necessary in its protection and excavation.
The bed is now of clay, and the side walls are of solid masonry 17 feet
high, 8 feet at the base, and 3 feet at the top. The north-eastern side
of the canal is occupied by a power house and is pierced by ten inlets
guarded by sentinel gates, each being the separate entrance to a wheel
pit in the power house, where the water is used and the power is
secured. The water as quickly as used is carried off by a tunnel to
the Niagara Eiver again.

The massive canal power house is a handsome building designed
by Stanford White, and likely to stand until Niagara, spendthrift
fashion, has consumed its way backward through its own crumbling
strata of shale and limestone to the base of it. This building is
outwardly of hard limestone, and inwardly of enamel brick and
ordinary brick coated with white enamel paint. It is 200 feet in
length at present, and has a 50-ton Sellers electric travelling crane
for the placing of machinery and the handling of any parts that need
repair. The wheel pit, over which the power house is situated, is a
long deep cavernous slot at one side under the floor cut in the rock,

272 Mr. Thomas Commerford Martin [June 19,

parallel with the canal outside. Here the water gets a fall of about
140 feet before it smites the turbines. The arrangement of the
dynamos generating the current up in the power house, is such that
each of them may be regarded as the screw at the end of a long shaft,
just as we might see it if we stood an ocean steamer on its nose with
its heel in the air. At the lower end of the dynamo shaft is the tur-
bine (Fig. 2) in the wheel pit bottom, just as in the case of the steamer
shaft we find attached to it the big triple or quadruple expansion
marine steam engine. Perhaps we might compare the dynamo and
the turbine to two reels, stuck one each end of a long lead pencil, so
that when the lower reel is turned the upper reel must turn also.
You might also compare the dynamos to bells up in the old church
steeple, and the turbines to the ringers in the porch, playing the
chimes and triple bob majors by their work on the long ropes that
hang down. The wheel pit which contains the turbines is 178 feet
in depth, and connects by a lateral tunnel with the main tunnel
running at right angles. This main tunnel is no less than 7000 feet
in length, with an average hydraulic slope of 6 feet in 1000. It has
a maximum height of 21 feet, and a width of 18 feet 10 inches, its net
section being 386 square feet. The water rushes through it and out
of its mouth of stone and iron at a velocity of 26J feet per second, or
nearly 20 miles an hour.

More than 1000 men were employed continuously for more than
three years in the construction of this tunnel. More than 300,000
tons of rock were removed, which have gone to form part of the new fore-
shore near the power house. More than 16,000,000 bricks were used
for the lining, to say nothing of the cement, concrete and cut stone.
The labour was chiefly Italian. The brick that fences in the headlong
torrent consists of four rings of the best hand-burned brick of special
shape, making a solid wall 16 inches thick. In some places it is
thicker than that. Into this tunnel discharges also by a special sub-
tunnel, the used-up water from the water wheels of the Niagara Falls
Paper Co. The turbines (Fig. 3) have to generate 5000 horse-power
each, at a distance of 140 feet underground, and to send it up to the
surface. For this purpose the water is brought down to each by the
supply penstock, made of steel tube and 7J feet in diameter. This
water impinges upon what is essentially a twin wheel, each receiving
part of the stream as it rushes in at the centre, the arrangement being
such that each wheel is three stories high, part of the water in the
upper tier serving as a cushion to sustain the weight of the entire
revolving mechanism. These wheels, which have thirty-two buckets
and thirty-six guides, discharge 430 cubic feet per second, and they
make 250 revolutions per minute. At 75 per cent, efficiency they
give 5000 horse-power. The shaft that runs up from each one to the
dynamo is of peculiar and interesting construction. It is composed
of steel f inch thick, rolled into tubes which are 38 inches in diameter.
At intervals this tube passes through journal bearings or guides that
steady it, at which the shaft is narrowed to 11 iaches in diameter and

1896.

on the Utilisation oj Niagara.

273

solid, flaring out again each side of the journal bearings. The speed
gates of the turbine wheels are plain circular rims, which throttle the
discharge on the outside of the wheels, and which, with the co-opera-
tion of the governors, keep the speed constant within 2 per cent, under
ordinary conditions of running. These wheels are of the Swiss design
of Faesch and Picard, and have been built by I. P. Morris & Co. of
Philadelphia, for this work.

The dynamos thus directly connected to the turbines are of the
Tesla two-phase type (Fig. 4). Each of these dynamos produces two

Fig. 4. — Niagara 5000 Horse-Power Two-Phase Alternator.

alternating currents, differing 90 degrees in phase from each other,
each current being of 775 amperes and 2250 volts, the two added to-
gether making in round figures very nearly 5000 horse-power. This
amount of energy in electrical current is delivered to the circuits for
use when the dynamo is run by the turbine at the moderate speed of
250 revolutions per minute, or say 4 revolutions per second. Here
then we have, broadly, a Tesla two-phase system embodying the novel
suggestions and useful ideas of many able men, among whom should
be specially mentioned Mr. L. B. Stillwell, the engineer of the
Vol. XV. (No. 90.) t

274 Mr. Thomas Commerford Martin [June 19,

Westinghouse Electric Co. "upon whom the responsibility was thrown
for its success.

Each generator, from the bottom of the bed plate to the floor of
the bridge above it is 11 feet 6 inches high. Each generator weighs
170,000 lbs. and the revolving part alone weighs 79,000 lbs. In
most dynamos the armature is the revolving part, but in this case
it is the field that revolves while the armature stands still. It is
noteworthy that if the armature inside the field were to revolve in
the usual manner instead of the field, its magnetic pull would be
added to the centrifugal force in acting to disrupt the revolving mass ;
but as it is, the magnetic attraction towards the armature now acts
against the centrifugal force exerted on the field, and thus reduces
the strains in the huge ring of spinning metal. The stationary
armature inside the field is built up of thin sheets of mild steel.
Along the edges of these sheets are 187 rectangular notches to
receive the armature winding in which the current is generated. This
winding is in reality not a winding, as it consists of solid copper bars
11.^ by -j^ inch, and there are two of these bars in every square hole,
packed in with mica as a precaution against heating. These copper
conductors are bolted and soldered to V-shaped copper connectors,
and are then grouped so as to form two separate independent
circuits. A pair of stout insulated cables connect each circuit with
the power house switchboard.

The rotating field magnet outside the armature consists of a huge
forged steel ring, made from a solid ingot of fluid compressed steel,
54 inches in diameter, which was brought to a forging heat and then
expanded upon a mandril, under a 14,000-ton hydraulic press, to the
ring, 11 feet 7^ inches in diameter. On the inside of this ring are bolted
twelve inwardly-projecting pole pieces of mild open hearth steel, and
the winding around each consists of rectangular copper bars encased
in two brass boxes. Each pole piece with its bobbin weighs about
li tons, and the speed of this mass of steel, copper and brass, is 9300
feet, or If miles per minute, when the apparatus is running at its
normal 250 revolutions. Not until the ring was sjDceded up to 800
revolutions, or six miles per minute, would it fly asunder under the
impulse of centrifugal force. As a matter of fact, 400 revolutions
is the highest speed that can be attained. This revolving field
magnet is connected with the shaft that has to turn it, and is supported
from above, by a six-armed cast steel spider keyed to the shaft, this
spider or driver forming a roof or penthouse over the whole machine.
The shaft itself is held in two bearings inside the castings around
which the armature is built up, and at the bearings is nearly 13
inches in diameter. At the lower end is a flange fitting with the
flange at the top of the turbine shaft, and at the upper end is a taper
over which the driver fits. The driver and shaft have a deep keyway,
and into this a long and massive key fits, holding them solidly
together. The driver is of mild cast steel, having a tensile strength
of 74,700 lbs. per square inch. The bushings of the bearings are

1896.] on the Utilisation of Niagara. 275

of bronze, with zigzag grooves in which oil under pressure is in
constant circulation. Grooves are also cut in the hub of each spider,
to permit the circulation of water to cool the bearings, this water
coming direct from the city mains at a pressure of 60 lbs. to the
square inch. The oil returns to a reservoir and is used over and
over again. Provision has been made against undue heating, and
plenty of cbance is given for air to circulate. This is necessary,
as about 100 horse-power of current is going into heat, due to the
lost magnetisation of the iron and the resistance in the conductors
themselves. Ventilators or gills in the driver are so arranged as
to draw up air from the base of the machine and eject it at consider-
able velocity, so that whatever heat is unavoidably engendered is
rapidly dissipated.

In almost all electrical plants the switchboard is a tall wall or slab
of marble or mahogany, not unlike a big front door with lots of knobs,
knockers and keyholes on it ; but at the Niagara power house it takes
the form of an imposing platform, or having in mind its controlling
functions, we may compare it to the bridge of an ocean steamer,
while the man in charge or handling the wheels answers to the
navigating officer. The ingenious feature is employed of using
compressed air to aid in opening and closing the switches. The air
comes from a compressor located at the wheel pit and driven by a
small water motor. It supplies air to a large cylindrical reservoir,
from which pipes lead to the various switches, the pressure being
125 lbs. to the square inch. Another interesting point is that the
measuring instruments on the switchboard do not measure the whole
current, but simply a derived portion of determined relation to that of
the generators. All told, less than a thirtieth of a horse-power gives
all the indications required. To the switchboard, current is taken
from the dynamos by heavy insulated cable, and it is then taken off by
huge copper bus bars which are carefully protected by layers of pure
Para gum and vulcanised rubber, two layers of each being used;
while outside of all is a special braided covering, treated chemically to
render it non-combustible. The calculated losses from heating in a
set of four bus bars carrying 25,000 horse-power, or the total output
of the first five Niagara generators, is only 10 horse-power. About
1200 feet of insulated cable have been supplied to carry the current
from the dynamos to the switchboard in the power house. It has
not broken down until between 45,000 and 48,000 volts of alternating
current were applied to it. There are 427 copper wires in that cable,
consisting of 61 strands laid up in reverse layers, each strand con-
sisting of seven wires. Next to the strand of copper is a wall of
rubber one-quarter inch thick, double coated. Over this is wrapped
absolutely pure rubber, imported from England and known as cut
sheet. Then come two wrappings of vulcanisable Para rubber, ne>*t
there is a wrapping of cut sheet, and on top of that are two more
rubber coats. This is then taped, covered with a substantial braid,
and vulcanised. The object in using the cut sheet is to vulcanise it

T 2

276 Mr. Thomas Commerf or d Martin [June 19,

by contact, in order to make it absolutely water-tight. This cable
weighs just over 4 lbs. to the foot, of which 3 lbs. are copper and 1 lb.
insulation.

We have thus advanced far enough to get our current on to the
bus bars, and the next step is to get it from them out of the power
house. This final work is done by extendinc; our bars, so to speak,
and carrying them across the bridge over the canal, into what is
known as the transformer house. It is here that the current received
from the other side of the canal is to be raised in potential, so that it
can be sent great distances over small wires without material loss.
Meantime we may note that the Niagara Falls Power Co. itself
owns more than a square mile around the power house, upon
which a large amount of power will be consumed in the near future
by manufacturing establishments of all kinds, and that it is already
delivering power in large blocks electrically for a great variety of
purposes. Special apparatus for this work has been built by the
General Electric Co. The current for the production of aluminium
is made " direct " by passing through static and rotary transformers,
while the Acheson Carborundum process uses the pure alternating
current. Besides this, the trolley road from Niagara to Buffalo is
already taking part of its power from the Niagara power house by
means of rotary transformers. For these and other local uses the
company has constructed subways in which to carry the wire across
its own territory. These subways are 5 feet 6 inches high, and
3 feet 10 inches wide inside. They are built up with 12 inches
of Portland cement and gravel, backed up with about 1 foot of
masonry at the bottom and extending about 3 feet up each side.
The electric conductors are carried on insulated brackets or insu-
lators arranged upon the pins along tlie walls. These brackets
are 30 feet apart. At the bottom of the conduit manholes are
holes for tapping off into side conduits, and along it all runs a
track, upon which an inspector can propel himself on a private
trolley car if necessary. Thus is distributed locally, the electric
power for which the consumer pays the very modest sum of
31. 17s. 6d. per electrical horse-power per annum delivered on the
wire, or about two guineas for a turbine horse-power, a rate which
is not to be equalled anywhere, in view of the absolute certainty of
the power, free from all annoyance, extra expense, or bother of any
kind on the part of the consumer.

It is a curious fact that the proposal to transmit the energy of
Niagara long distances over wire should have been regarded with so
much doubt and scepticism, and that the courageous backers of the
enterprise should have needed time to demonstrate that they were
neither knaves nor fools, but simply brave, far-seeing men. We have
to-day parallel instances to Niagara in the transmission of oil and
natural gas. Oil is delivered in New York City over a line of pipe
which is at least 400 miles long, and which has some thirty-five
pumping stations en route, the capacity of the line being 30,000

1896.] on the Utilisation of Niagara, 277

barrels a flay. All that oil has first to be gathered from individual
wells in the oil region, and delivered to storage tanks with a capacity
of 9,000,000 barrels of oil. Chicago, Philadelphia and Baltimore are
centres for similar systems of oil pipe running hundreds of miles over
hill and dale. As for natural gas, that is to-day sent in similar
manner over distances of 120 miles, Chicago being thus supplied from
the Indiana gas fields ; and the gas has its pressure raised and lowered
several times on its way from the gas well to the consumer's tap,
just as though it were current from Niagara.

We must not overlook some of the fantastic schemes proposed for
transmitting the power of Niagara before electricity was adopted.
One of them was to hitch the turbines to a big steel shaft running
through New York State from east to west, so that where the shaft
passed a town or factory, all you had to do was to hitch on a belt or
some gear wheels and thus take off all the power wanted. Not much
less expensive was the plan to have a big tube from New York to
Chicago with Niagara falls at the centre, and with the Niagara
turbines hitched to a monster air compressor which should compress
air under 250 lbs. pressure to the square inch in the tube.

So far as actual electrical long-distance transmission from Niagara
is concerned, it can only be said to be in the embryonic stage, for the
sole reason that for nearly a year past the Power Company has beon
unable to get into Buffalo, and that not until last year was it able to
arrive at acceptable conditions, satisfactory alike to itself and to the
city. Work is now being pushed, and by June 1897 power from the
Falls will, by contract with the city, be in regular delivery to the
local consumption circuits at Buffalo, twenty-two miles away. But
the question arises, and has been fiercely discussed, whether it will
pay to send the current beyond Buffalo. Recent ofiicial investigations
have shown that steam power in large bulk under the most favourable
conditions, costs to-day in Buffalo lOZ. per year per horse-power and
upwards. Evidently Niagara power starting at 2/. on the turbine
shaft, or say less than il. on the line, has a good margin for effective
competition with steam in Buffalo.

As to the far-away places, the well known engineers, Prof. E. J.
Houston and Mr. A. E. Kennelly, have made a most careful estimate
of the distance to which the energy of Niagara could be economically
transmitted by electricity. Taking established conditions, and prices
that are asked to-day for apparatus, they have shown, to their own
satisfaction at least, that even in Albany or anywhere else in the same
radius, 330 miles from the Falls, the converted energy of the great
cataract could be delivered cheaper than good steam engines on the
spot could make steam power with coal at the normal price there of
12s. per ton.

What this enterprise at Niagara aims to do is not to monopolise
the power but to distribute it ; and it makes Niagara, more than it ever
was before, common property. After all is said and done, very few
people ever see the Falls, and then only for a chance holiday once in a

278 Mr. Thomas Commerford Martin [June 19,

lifetime ; but now the useful energy of the cataract is made cheaply
and immediately available, every day in the year, to hundreds and
thousands, even millions of people, in an endless variety of ways.

We must not omit from our survey the Erie Canal, in the revival
and greater utilisation of which as an important highway of commerce
Niagara power is expected to play no mean part. In competition
with the steam railway, canals have suffered greatly the last fifty
years. In the United States, out of 4468 miles of canal built at a
cost of 40,000,000/., about one-half has been abandoned and not much
of the rest pays expenses. Yet canals have enormous carrying
capacity, and a single boat will hold as much as twenty freight cars.
The New York State authorities have agreed to conditions by which
Niagara energy can be used to propel the canal boats at the rate of
4Z. per horse-power per year. Where steam-boat haulage for 242
tons of freight now costs about 6^cZ. a boat mile, it is estimated that
electric haulage will cost not to exceed b\d. ; while, with the energy
from Niagara at only 4Z. per horse-power per year, it will cost much
less. Some two years ago the first attempt was made in the United
States on the Erie Canal, with the canal boat " F. W. Hawley," when
the trolley system was used with the motor on the boat, as it is on an
electric car, driving the propeller as if it were the car wheels.
Another plan is that of hauling the boat from the tow-path, and that
is what is now being done with the electric system of Mr. Eichard
Lamb on the Erie Canal at Tonawanda, near Niagara. Imagine an
elevator shaft working lengthwise instead of vertically. There is
placed on poles, a heavy fixed cable on which the motor truck rests,
and a lighter traction cable is also strung that is taken up and paid
out by a sheave, as the motor propels itself along and pulls the canal
boat to which it is attached. If the boats come from opposite direc-
tions they simply exchange motors, just as they might mules or
locomotives, and go on without delay.

On its property at Niagara the Power Company has already begun
the development of the new village called Echota, a pretty Indian
name which signifies " Place of Refuge." I believe it is Mr. W. D.
Howells, our American novelist, who in kindred spirit speaks of the
" Repose " of Niagara. It was laid out by Mr. John Bogart, formerly
State Engineer, and is intended to embody all that is best in sanita-
tion, lighting and urban comfort. It does not need the eye of faith to
see here the beginning of one of the busiest, cleanest, prettiest and
healthiest localities in the Union. The working man whose factory is
not poisoned by smoke and dust, whose home was designed by distin-
guished architects, whose streets and parks were laid out by celebrated
engineers, and whose leisure is spent within sight and sound of lovely
Niagara, has little cause for grumbling at his lot.

The American company has also preempted the great utilisation
of the Canadian share of Niagara's energy. The plan for this work
proposes the erection of two power houses of a total ultimate capacity
of 125,000 horse-power. Each power house is fed by its own canal

1896.] on the Utilisation of Niagara. 279

and is therefore an independent unit. Owing to the better lay of the
land, the tunnels carrying off the water discharged from the turbines
on the Canadian side will have lengths respectively of only 300 and
800 feet, thus avoiding the extreme length and cost unavoidable on
the American side. With both the Canadian and American plants
fully developed, no less than 350,000 horse-power will be available.
The stationary engines now in use in New York State represent only
500,000 horse-power. Yet the 350,000 horse-power are but one-
twentieth of the 7,000,000 horse-power which Prof. Unwin has
estimated the Falls to represent theoretically. If the 350,000 horse-
power were estimated at 4Z. per year per horse-power, and should
replace the same amount of steam power at lOZ., the annual saving
for power in New York State alone would be more than 2,000,000Z.
per year.

Let me by way of conclusion emphasise the truth that this splendid
engineering work leaves all the genuine beauty of Niagara untouched.
It may even help to conserve the scene as it exists to-day, for the
terrific weight and rush of waters over the Horse Shoe Fall is eating
it away and breaking its cliff into a series of receding slopes and
rapids; so that even a slight diminution of the whelming mass of
wave will to that extent lessen disruption and decay. Be that so or
not so, those of us who are lovers of engineering can now at Niagara
gratify that taste in the unpretentious place where some of this vast
energy is reclaimed for human use, and then as ever join with those
who, not more than ourselves, love natural beauty, and find with them
renewed pleasure and delight in the majestic, organ-toned and eternal
cataract.

[T. C. M.]

280 General Monthly Meeting. [July 6,

GENERAL MONTHLY MEETING,
Monday, July 6, 1896.

Sir James Criohton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Eight Hon. Lord Windsor,
Herbert Page, Esq. F.R.C.S.
Alfred Suart, Esq.

were elected Members of the Royal Institution.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

The Lords of the Admiralty — Report of the Astronomer Royal to the Board of

VisitorB, 1896. 4to.
Appendix to the Nautical Almanac for 1900. 8vo. 1896.
The Governor-General of India— Mt-moirs, Vol. XXVII. Tart 1. 8vo. 1895.
Palseontologia Indica. Series XIII. Salt Range FoBsils, Vol. II. Fossils

from the Ceratite Formation, by W. Waagen. Series XV. Himalayan

Fossils, Vol. II. Trias, Part 2, The Cephalopoda of the Muschclkalk, by

C. Diener. 4to. 1895.
The Secretary of State for India— Bengal Public Works Department. List of

Ancient Monuments in Bengal. 4to. 1896.
Indian Department of Revenue and Agriculture. Statistical Atlas of India.

2nded. fol. 1895.
Accademia del Lincei, Beale, Roma — Classe di Scienze Fisiche, Matematiche e

Naturali. Atti, Serie Quinta : Rendiconti. 1*^ Semestre, Vol. V. Fasc. 10,

11. 8vo. 1896.
Agricultural Society of England, Royal—Jomnal, 3rd Series, Vol. VII. Part 2.

8vo. 1896.
American Philosophical /Soc/ef?/— Proceedings, Vol. XXXIV. No. 49. 8vo. 1895.
Amherst, The Hon. Alicia {the Author) — A History of Gardening in England.

8vo. 1895.
Asiatic Society of Bengal— J omnol, Vol. LXIV. Part 1, No. 4; Vol. LXV.

Part 2, No. 1. 8vo. 1896.
Proceedings, 1895, Nos. 9, 10; 1896, No. 1. 8vo.
Astronomical Society, Royal — Monthly Notices, Vol. LVI. No. 8. 8vo. 1896.
General Index to Vols. XXX.-LII. of the Monthly Notices of the R.A.S. 8vo.

1896.
Bankers, Institute o/— Journal, Vol. XVII. Part 6. 8vo. 1896.
Bech, M. M. (the Author) — Theorie mole'culaire du re'cepteur Bell. 8vo. 1896.
Boston Society of Natural History— Vioceedings, Vol. XXVII. Parts 1-6. 8vo. 1896.
British Architects, Royal Institute o/— Journal, 3rd Series, Vol. III. Nos. 15, 16.

4to. 1896.
British Astronomical Association — Memoirs, Vol. IV. Part 2 ; Vol. V. Part 1. 8vo.

1896.
Journal, Vol. VI. Nos. 1 «, ^vo. 1896.

1896.] General Monthly Meeting, 281

Camera Club — Journal for June, 1896. 8vo.
Canadian Institute — Transactions, 1892-93, No. 8. 8vo. 1895.
Chemical Industry, Society of — Tournal, Vol. XV. No. 5. 8vo. 1896.
Chemical Society — Journal for June, 1896. 8vo.

Proceedings, Nos. 166, 167. 8vo. 1895-96.
Civil Engineers, Institution of — Proceedings, Vol. CXXIV. 8vo. 1896.

List of Members, &c. 8vo. 1896.
Congress of Archaeological Societies — Index of Arcbseological Papers published iu

1893 (third issue of series). 8vo. 1894.
Cornwall Folytechnic Society, J?o?/aZ— Sixtv-third Annual Report. 8vo. 1895,
Cornwall, Royal Institution of — Journal, Vol. XII. Part 2. 8vo. 1896.
Cracovie, Academic des Sciences — Bulletin, 1896, Nos. 4, 5. 8vo.
Curried: Co. Sir Donald — Tantallou Castle: the Story of the Castle and the

Ship, told by E. R. Pennell, with illustrations. 4to. 1895.
Editors — American Journal of Science lor June, 1896. 8vo.

Analyst for June, 1896. 8vo.

Anthony's Photographic Bulletin for June, 1896. 8vo.

Athenaeum for June, 1896. 4to.

Autlior for June, 1896. 8vo.

Bimetallist for June, 1896.

Brewers' Journal for June, 1896. 8vo.

Chemical News for June, 1896. 4to.

Chemist and Druggist for June, 1896. 8vo.

Electrical Engineer for June, 1896. ful.

Electrical Engineering for June, 1896. 8vo.

Electrical Review for June, 1896. 8vo.

Electric Plant for Juno, 1896. 4to.

Electricity for June, 1896. 8vo.

Engineer for June, 1896. fol.

Engineering for June, 1896. fol.

Engineering Review and Metal Worker for June, 1896. 8v().

Homoeopathic Review for June, 1896. Svo.

Horological Journal for June, 1896. 8vo.

Industries and Iron for June, 1896. fol.

Invention for June, 1896.

Law Journal for June, 1896. Svo.

Lightning for June, 1896. Svo.

Loudon Technical Education Gazette for .Tune, 1896. Svo.

^Machinery Market for June, 1896. Svo.

Nature for June, 1896. 4to.

Nuovo Cimeuto for May, 1896. Svo.

Photographic News for June, 1896. Svo.

Science Sittings for June, 1896.

Technical World for June, 1896. Svo.

Transport for June, 1896. fol.

Tropical Agriculturist for May, 1896.

Zoophilist for June, 1896. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXV. No. 123. Svo. 1890.
Field Columbian Museum, Chicago — Annual Report of the Director. Svo. 1895.

Flora of West Virginia. By C. F. Millspaugli and L. W. Nuttall. Svo. 1896.
Florence, Biblioteca Nazionale Cen<r«Ze— Bolletino, Nos. 250-252. Svo. 1896.
Franklin Institute — Journal for June, 1896. Svo.

Geographical Society, Royal — Geographical Journal for June, 1896. Svo.
Greenock Philosophical Society — Life and Work of Hirn and the experimental
theory of the Steam Engine. By W. C. Unwin. Svo. 1896.

Thirty-fifth Annual Report, 1895-96. Svo. 1896.
Button, Arthur W. Esq, {the A^dhor)— The Vaccination Question. New edition.

Svo. 1896.
Imperial Institute —Impvnal Institute Journal for June, 1896.

282 General Monthly Meeting. [July 6,

Johns HopMns University— Vni\eTB\ij Studies, Fourteenth Series, Nos. 6, 7.
8vo. 1896.
American Chemical Journal, Vol. XVIII. No. 6. 8vo. 1896.
American Journal of Philology, Vol. XVI. No. 2. 8vo. 1895.
Leicester Public i/6mWes— Twenty-fifth Annual Keport, 1895-96. 8vo.
Linnean Society— J omnal, Nos. 215, 216. 8vo. 1896.
Madras Government ilfwseMm— Anthropology of the Todas and Kotas of the Nilgiri

Hills, &c. By E. Thurston. 8vo. 1896.
Manchester Geological /Soctef?/— Transactions, Vol. XXIV. Part 8. 8vo. 1896.
Navy League — Navy League Journal for June, 1896. 8vo.
Neio York Academy of Snences—^lemoixB, Vol. I. Part 1. 4to. 1895.
Odontological Society of Great J5nYam— Transactions, Vol. XXVIII. Nos. 6, 7.

8vo. 1896.
Paris, Societe Frangaise de Physique— BnWeim^ Nos. 80-82. 8vo. 1896.
Pharmaceutical Society of Great Britain— Somn&l for June, 1896. 8vo.
Philadelphia, Geographical Cluh o/— Bulletin, Vol. II. No. 1. 8vo. 1896.
Photographic Society, Boyal — Photographic Journal for May, 1896. 8vo.
Physical Society of ZonfZow— Proceedings, Vol. XIV. Part 6. 8vo. 1896.
Badclife Observatory Trustees — Results of Astronomical and Meteorological
Observations made at the Kadcliflfe Observatory, Oxford, in the years 1888-
89. Vol. XLVI. 8vo. 1896.
Borne, Ministry of Public Works— Glornaie del Genio Civile, 1896, Fasc. 3. And

Designi. fol.
Boyal Irish ^carfemi/— Transactions, Vol. XXX. Parts 18-20. 4to. 1896.
Proceedings, 3rd Series, Vol. III. No. 5. 8vo. 1896.
List of Members. 8vo. 1896.
Boyal Society of Literature — Keport and List of Fellows. 8vo. 1896.
Boual Society of London— Proceedings, No. 357. 8vo. 1896.

Philosophical Transactions, Vol. CLXXXVI. B. No. 135 ; Vol. CLXXXVII. B.
No. 136, A. No. 179. 4to. 1896.
Sanitary Iiistitute—IWustrsLted List of Exhibits to which medals have been

awarded at the exhibitions of the Sanitary Institute. Svo. 1896.
Selborne Society — Nature Notes for June, 1896. Svo.
Society of 4r<s— Journal for June, 1896. 8vo.
United Service Institution, i?o?/a/— Journal, No. 220, Svo. 1S96.
United States Department of Agriculture {Office of Experiment Stations) — Record,
Vol. VILNo. 6. Svo. 1896.
Bulletin, No. 28. Svo. 1896.

Monthly Weather Review for December, 1895. Svo.
Climate and Health, Vol. II. No. 2. Svo. 1896.
Report of the Chief of the Weather Bureau for 1894. Svo. 1895.
United States Department of the Interior {Census Office) — Report on the Statistics
of Agriculture in the United States at the Eleventh Census, 1890. 4to.
1895.
Report on Transportation Business in the United States at the Eleventh Census,

1890, Part I. Transportation by Land. 4to. 1895.
Report on Vital and Social Statistics in the United States, Part III. Statistics
of Deaths. 4to. 1894.
United States Patent 0>'ce— Official Gazette, Vol. LXXIV. Nos. 10-13; Vol.

LXXV. Nos. 1-4. Svo. 1896.
Verein zur Beforderung des Gewerbfleisses in Preussen — Verhandlungen, 1896,

Heft 5. 4to. 1896.
Victoria Institute — Journal of the Transactions, Vol. XXVIII. No. 112. Svo.

1896.
Yale University Astronomical Observatory — Transactions, Vol. I. Part 5. 4to. 1896.
Yerkes Observatory^ University of Chicago — Organisation of the Yerkes Observa-
tory. By E. Hale. Svo. 1896.
Zoological Society of London — Proceedings, 1896, Part 1. Svo. 1896.

1896.] General Monthly Meeting. 283

GENEKAL MONTHLY MEETING,

Monday, November 2, 1896.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer uml
Vice-President, in the Chair.

George Cawston, Esq.

J. Broiighton Dugdale, Esq. J. P. D.L.

Henry Harben, Esq. J.P.

John H. Usmar, Esq.

were elected Members of the Eoyal Institution.

The Special Thanks of the Members were returned for the
following Donations to the Fund for the Promotion of Experimental
Research at Low Temperatures : —

The Proprietors of The Times .. .. £100

Dr. Ludwig Mond .. .. .. 60

Professor Dewar .. .. .. 50

Sir Andrew Noble .. .. .. 100

The following reply from the Right Hon. Lord Kelvin to the
Address from the Members of the Royal Institution on the occasion
of the Jubilee of his appointment to the Chair of Natural Philosophy
in the University of Glasgow, was read and ordered to be entered on
the Minutes.

" The University, Glasgow.

" For the Address which I have had the honour to receive from the Eoyal
Institution on the occasion of the Jubilee of my Professors liip of Natural Philo-
sophy in the University of Glasgow, I desire to express my warmest thanks.
I value very highly the great honour which it has conferred on me. The
friendly appreciation of ray scientific work contained in the address is most
gratifying. I feel deeply touched by the great kindness to myself, and the
good wishes for my welfare of which it gives expression.

KELVIN.

July 6, 1896."

The Managers reported that at their Meeting held this day, they
litid elected Professor Augustus D. Waller, M.D. F.R.S. Fullerian
Professor of Physiology for three years (the appointment dating from
January 13, 1897).

28i General Monthly Meeting. [Nov. 2,

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

The Secretary of state for India — South Indian Inscriptions. By E. Hultzsch.

Vo]. II. Part 3. 4to. 1896.
The Lords of the Admiraltij — Greenwich Observations for 1893. 4to. 1896.
Greenwich Spectroscopic and Photographic Results for 1893. 4to. 1896.
Cape Meridian Observations, 1888 to 1891. 2 vols. 4to. 1895.
The Governor-General of Jndm— Geological Survey of India. Records, Vol.

XXIV. Part 2. 8vo. 1896.
The British Museum (Natural History)— Csitalogue of Birds, Vol. XXIV. 8vo.
1896.
Catalogue of Snakes, Vol. III. 8vo. 1896.

Catalogue of the Fossil Bryozoa. The Jurassic Brynzoa. 8vo. 1896.
Catalogue of Madreporarian Corals, Vol. II. 4to. 'l896.
The Meteorological Office — Monthly Current Cliarts for tlie Indiiin Ocean, fol.
Accademia del Lincei, Meale, Roma — Atti, Serie Quinta : Rendiconti. Classe di
Scienze Morali, etc. Vol. V. Fasc. 4-9. 8vo. 1896.
Classe di Scienze Fisiche, etc. 1" Semestre, Vol. V. Fasc. 12 ; 2° Semestrc,
Vol. V. Fasc. 1-7. 8vo. 1896.
Agricultural Society of England, Royal— J ouvnul, Third Series, Vol. VII. Part 3.

8vo. 1896.
American Association for the Advancement of Science — Proceedings, Forty-fourth

Meeting. 8vo. 1896.
American Geographical Society— BnWeiin, Vol. XXVIII. No. 2. 8vo. 1896.
Ameri'-an Philosophical Society — Proceedings, No. 150. 8vo. 18y6.
Amsterdam Roycd Academy of Sciences — Publications, 1895-96. 8vo.
Aristotelian So"ciety —Froceedings, Vol. III. No. 2. 8vo. 1896.
Asiatic Society of Bengal— Jonrnii\, Voh LXV. Part 1, Nos. 1, 2; Part 2, No. 2.

Proceedings, 1896, Nos. 2-5. 8vo. 1896.
Asiatic Society, Royal — Journal for Jnly and Oct. 1896. 8vo.
Astronomical Society, Royal — List of Fellows. 8vo. 1896.

Montlily Notices, Vol. LVI. No. 9. 8vo. 1896.
Australian Museum, Sydney— Anux\a,\ Report of Trustees for 1895. 8vo. 1^96.
Banhers, Institute o/— Journal, Vol. XVII. Part 7. 8vo. 1896.
Basel, Natiirforschenden Gesellschaft — Verhandlungen, Band XI. Heft 2. 8vo.

1896.
Berlin, Royal Prussian Academy of Sciences — Sitzungsberichte, 1896, Nos. 1-39.

8vo.
Boston Society of Natural History — Proceedings, Vol. XXVII. pp. 7-74. 8vo.

1896.
Boston, U.S.A., Public Library — Monthly Bulletin of Books added to the

Library, Vol. I. Nos. 1-8. 8vo. 1896.
British Architects, Royal Institute of— J ouriuil, 1895-96, Nos. 17-20, and Calendar.

8vo.
British Astronomical Association — Journal, Vol. VI. Nos. 9, 10. 8vo, 1896.
Buenos Aires, Museo Nacional de — Annales, Tonio IV. 8vo. 1895.
Cambridge Philosophical Society — Proceedings, Vol. IX. Part 3. 8vo. 1896.

Transactions, Vol. XVI. Part 1. 4to. 1896.
Camhridge University Library— Annneil Report of the Library Syndicate, 1895.

8vo.
Camera Club — Journal for July-Oct. 1896. 8vo.
Cape of Good Hope, The Surveyor- General of the Colony of the- Report on Colonel

Morris's Geodetic Survey of South Africa. By I>. Gill. fol. 1896.
Chemical Industry, Society o/— Journal, Vol. XV. Nos. 6-9. 8vo. 1896.
Chemical Society — Journal for July-( 'ct. 1896. 8vo.
Jubilee of the Chemical Society, 1891. 8vo. 1896.
Proceedings, Nos. 166-168. 8vo. 1896.

1896.] General Monthly Meeting. 285

C:ty of London Co7Zef/e— Calendar, 1896-97. 8vo. 1896.

Civil Engineers' Institution— Vroceedings, Vols. CXXV. CXXVI. 8vo. 1896.

Clinical Society of London — Transactions, Vol. XXIX. 8vo. 1896.

Colonial Institute, Royal— Proceedings, Vol. XXVII. 1895-96. 8vo. 1896.

Cornwall, Royal Institution of — Journal, Vol. XTII. Part 1. 8vo. 1896.

Cracovie, VAcademie des Sciences — Bulletin International, 1896, Nos. 6, 7. 8vo.

Cutler, Ephraim, Esq. M.D. LL.D. (the Author) — The American Blood Test lor

Cattle Tuberculosis. 8vo. 1896.
Dax, Sorietide ^orrZa— Bulletin, 1896. Premier Trimestre. 8vo. 1896.
Dewar, Professor, M.A. LL.D. F.R.S. M.R.I. — Transactions of the Seventh Inter-
national Congress of Hygiene and Demography, 1891, Vols. I.-XIII. 8vo.
1892-93.
Ea^t India Association — Journal, Vol. XXVIII. No. 9. 8vo. 1896.
Editors — American Journal of Science for July, Aug. Oct. 1896. 8vo.

Analyst for July-Oct. 1896. 8vo.

Anthony's Photographic Bulletin for July-Oct. 1896. 8vo.

Astrophysical Journal for July-Oct. 1896. 8vo.

Ateneo Veneto for 1895. 8vo.

Athenaeum for July-Oct. 1896. 4to.

Author for July-Oct. 1896

Bimetallist for July-Oct. 1896.

Chemical News for July-Oct. 1896. 4to.

Chemist and Druggist for July-Oct. 1896. 8vo.

Education for July-Oct. 1896. 8vo.

Electrical Engineer for July-Oct. 1896. fol.

Electrical Engineering for July-Oct. 1896.

Electrical Keview for July-Oct. 1896. 8vo.

Electric Plant for July-Oct. 1896. 8vo.

Engineer for July-Oct. 1896. fol.

Engineering for July-Oct. 1896. fol.

Homoeopathic Review for July-Oct. 1896.

Horological Journal for July-Oct. 1896. 8vo.

Industries and Iron for July-Oct. 1896. fol.

Invention for July-Oct. 1896. 8vo.

Journal of Physical Chemistry, Vol. I. No. 1. 8vo. 1896.

Law Journal for July-Oct. 1896. 8vo.

Machinery Market for July-Oct. 1896. 8vo.

Monist for July-Oct. 1896. 8vo.

Nature for July-Oct. 1896. 4to.

New Church Magazine for July-Oct, 1896. 8vo.

Nuovo Cimento for June-Aug. 1896. 8vo.

Physical Review for July-Oct. 1896. 8vo.

Science Siftings for July-Oct. 1896. 8vo.

Scientific African for April, 1896. 8vo.

Terrestrial Magnetism for July, 1896. 8vo.

Transport for July-Oct. 1896. fol.

Travel for July, Aug. Oct. Nov. 1896.

Tropical Agriculturist for June- Oct. 1896. 8vo.

Zoophilist for July-Oct. 1896. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXV. No. 124. Svo. 1896.

Bye-Laws and List of Members. 8vo. 1896.
Engineers, Institution of Junior— Record of Transactions, Vol. V. 1894-95. 8vo.

1896.
Essex County Technical Laboratories, Chelmsford — Journal for June-Sept. 1896.

8vo.
Florence, Bihlioteca Nazionale Centrals — Bollettino, Nos. 253-59. Svo. 1896.
Florence, Reale Accademia dei GeorgofiU — Atti, Vol. XIX. Disp. 2. 8vo. 1896.
Franklin Institute — Journal for July-Oct. 1896. 8vo.

Fulcomer, Daniel, Esq. {the Aiithor) — Instruction in Sociology in Institutions of
Learnins. 8vo.

286 General Monthly Meeting. [Nov. 2,

Geographical Society, 7?o?/aZ— Geographioal Journal for July-Oct. 1896. 8vo.

Geological Society— QnnYterlj Journal, No. 207. 8vo. 1896.

Harlem, Societe Hollandaise des /Sciences— Archives Neerlandaises, Tome XXX.

Livr. 2. 8vo. 1896.
Eenslow, Bev. George, M.A. F.E.S. (the Author)— The Plants of the Bible. 8vo.

1896.
Eoepll, Ulrico, Esq. (the Pu'bUsher)—X.X Anni di Vita editoriale. Edizioui

Hoepli, 1872-96. Milan. 8vo. 1896.
Horticultural Society, Royal— Journal, Vol. XX. Part 1. 8vo. 1896.
Imperial Institute — Imperial Institute Journal for July-Oct. 1896.
Increased Armaments Protest Committee — Empire, Trade and Armaments: An

exposure. 8vo. 1896.
Iron and Steel Institute — Journal, 1896, No. 1. 8vo.

Johns HopMns University — American Chemical Journal for July-Oct. 1896.
University Circulars, Nos. 125, 126. 8vo. 1896.
American Journal of Philology, Vol. XVII. Nos. 1, 2. 8vo. 1896.
Life-Boat Institution, Eoyal National — Journal for Aug. 1896. 8vo.
Linnean Society— Catalogne of the Library. New edition. 8vo. 1896.
Index to the Journal, Zoology, 1838-90. 8vo. 1896.
Journal, Nos. 217, 163. 8vo. 1896.
Transactions, Zoology, Vol. VI. Parts 4-6. 4to. 1896.

Botany, Vol. IV. Parts 3, 4 ; Vol. V. Parts 2-4. 4to. 1895-96.
London County Council Technical Education Board — London Technical Educa-
tion Gazette for July-Oct. 1896. 8vo. 1895.
Madras Government Museum — Administration Keport for 1895-96. 8vo. 1896.
Manchester Geological Society — Transactions, Vol. XXIV. Part 9. 8vo. 1896.
Massachusetts Institute of Technology — Technology Quarterly and Proceedings of

the Society of Arts, Vol. IX. No. 3. 8vo. 1896.
Massachusetts State Board of Health— Tvientj -sixth Annual Eeport. 8vo. 1895.
Mechanical Engineers, Institution o/^Proceedings, 1896, No, 1. 8vo.
Meteorological Society, Royal — Meteorological Record, No. 60. 8vo.

Quarterly Journal, No. 99. 8vo. 1896.
Meux, Lady — Some Account of the Collection of Egyptian Antiquities in the
possession of Lady Meux, of Theobalds Park. By E. A. W. Budge. 2nd
edition. 4to. 1896. (Printed for private circulation.)
Mexico, Sociedad Cientifica, " Antonio Alzcde " — INIemorias y Revista, Tomo VIII.

Nos. 5-8; Tomo IX. Nos. 7-10. 8vo. 1895-96.
Microscopical Society, Royal — Journal, 1896, Parts 3-5. 8vo.
Munich, Royal Bavarian Academy of Sciences — Abhandlungen, Band XVII I.
No. 3. 4to. 1896.
Sitzungsberichte, 1896, Heft 1, 2. 8vo.
Musical Association — Proceedings, Twenty-secoml Session, 1895-96. Svo. 1896.
Navy League — Navy League Journal, July-Oct. 1896. 4to.
New South Wales, Agent-General for — The Wealth and Progress of New South
Wales. By T. A. Coghlan. 2 vols. 8vo. 1895-96.
New South Wales. Edited by F. Hutchinson. 8vo. 1896.
New York Academy of Sciences — Annals, Vol. IX. Nos. 1-3. Svo. 18!t6.

Index, Vol. VIII. 8vo. 1896.
Nova Scotian Institute of Science — Proceedings and Transactions, Vol. IX. Part 1.

Svo. 1896.
Numismatic Society — Numismatic Chronicle, 1896, Part 2. Svo.
Odontological Society of Great Britain — Transactions, Vol. XXVIII. No. 8. Svo.
1896.
List of Members, 1896-97. Svo.
Paris, Societe Frangaise de Physique — Bulletin, No. 83. Svo. 1896.

Seances, 1895, Ease. 4; 1896, Ease. 1. Svo.
Pharmaceidical Society of Great Britain — Journal for July-Oct. 1896. Svo.
Philadelphia, Academy of Naturcd Sciences — Proceedings, 1896, Part 1. Svo.
Photographic Society, Royal — The Photograpliic Journal for June-Sept, 1896.

1896.] General Monthly Meeting. 287

Physical Society of London — Proceedings, Vol. XIV. Parts 7-10. 8vo. 1896.

Bio de Janeiro, Observatorio — Annuario for 1896. 8vo. 1895.

Bochechouarf, La Societedes Amis des Sciences et Arts — Bulletin, Tome V. Nos. 5, 6.

8vo. 1895-96.
Rochester Academy of Science — Proceedings, Vol. III. Part 1. 8vo. 1896.
Borne., Ministry of Public Works — Gioruale del Genio Civile, 1896, Fasc. 4-5.

And Designi. fol.
Boyal College of Surgeons of England — Calendar, 1896. 8vo.
Boyal Engineers, Corps o/— Foreign Translation Series, Vol. I. Paper 3. 8vo.

1896.
Boyal Society of Canada — Proceedings and Transactions, Second Series, Vol. I.

8vo. 1895.
Boyal Society of Edinburgh — Proceedings, Vol. XXI. No. 1, No. 2. 8vo 1895-
96.
Transactions, Vol. XXVIII. Parts 1, 2. 4to. 1896.
Botjal Society of London — Philosophical Transactions, Vol. CLXXXVII B
No. 137 ; Vol. CLXXXVIII. A, Nos. 178, 180, 182. 4to. 1896.
Proceedings, No. 358-361. 8vo. 1896.
Sanitary Institute— J omnal. Vol. XVII. Part 2. 8vo. 1896.
Saxon Society of Sciences, Royal —
Philologisch-Historische Classe —

Berichte, 1896, Nos. 1-3. 8vo. 1896.
Selborne Society— !>! suture Notes for July-Oct. 1896. 8vo.
Society of Antiquaries— Froceediuga, Vol. XVI. No. 1. 8vo. 1896.

Archffiologia, 2 S. Vol. V. 4to. 1896.
Smithsonian Institution — Bureau of Ethnology. Thirteenth Annual Report,

1891-92. 4to. 1896.
Society of Apothecaries of London — Calendar, 1896-97. 8vo.
Society of Arts— Journal for July-Oct. 1896. 8vo.
Statistical Society, Boyal — Journal, Vol. LIX. Part 2. 8vo. 1896.
St. Petersburg, Academic Imperiale des Sciences — Memoires, 8th Series, Tome I.

No. 9 ; Tome II. ; Tome III. Nos. 1-6; Tome IV. No. 1. 4to. 1895-96.
Sweden, Boyal Academy of Sciences — Handlingar (Memoires), Band XXVII.

4to. Bihang, Vol. XXI. 8vo. 1895-96.
Tacchini, Prof. P. Hon. Mem. B.I. (the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXV. Disp. 6-9. 4to. 1896.
Tasmania, Boyal Society o/— Papers and Proceedings for 1894-95. 8vo. 1896.
Thorpe, Professor T. E. LL.D. F.B.S. M.B.I. {the ^wf/ior)— Humphry Davy, Poet

and Philosopher. 8vo. 1896. (Century Science Series.)
Toronto, University of — University of Toronto Quarterly, Nov. 1895-June, 1896.

8vo.
United Service Institution, Boyal— Journal for July-Oct. 1896. 8vo.
United States Department of Agriculture — North American Fauna, Nos. 10-12.
8vo. 1896.
Experiment Station Record, Vol. VII. No. 8-11. Svo. 1896.
Monthly Weather Review for Jan.-June, 1896, and Annual Summary for

1895. 8vo.
Climate and Health, Vol. II. No. 3. 8vo. 1896.
United States Department of the Interior, Census Office — Report on Manufacturinf>-
Industries in the U.S. at the Eleventh Census, 1890, Parts 1, 2. 4to. 1895^
Report on Real Estate Mortgages. 4to. 1895.
Abstract of the Eleventh Census, 1890. 8vo. 1896.
United States Patent O^ce— Official Gazette, Vol. LXXV. Parts 5-13 ; Vol.
LXXVI. Parts 1-3. ' 8vo. 1896.
Alphabetical List, Vol. LXXIII. _ 8vo.
United States Geological Survey — Sixteenth Annual Report, 1894-95, Parts 2-4
4to. 1895.
Fifteenth Annual Report, 1893-94. 4to. 1895.
Bulletins, 123-126, 128, 129, 131-134. 8vo. 1895.
Geological Atlas of the U.S. Sheets 7, 13-25. fol. 1894-96.

288 General MontUy Meeting. [Nov. 2,

Verein zur Beforderung des Gewerbjleisses in Preussen — Verhandlungen, 189G,

Heft 6-8. 4to.
Vienna, Geological Institute, Imperial — Verhandlungen, 1896, Nos. 6-9. 8vo.
Wright & Co. Messrs. J. (the Publishers) — The Medical Annual for 1896. Svo.
Yale University Observatory — Report for 1895-96. Svo.
Zoological Society of London — Proceedings, 1896, Part 2. 8vo. 1896.

1896 ] General Monthly Meeting, 289

GENERAL MONTHLY MEETING,

Monday, December 7, 1896.

Sir James Ckichton-Beowne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Hon. and Eev. William Byron,
Sir Gervas Powell Glyn, Bart.
Alexander Scott, Esq. M.A. D.Sc.
Mrs. T. B. Sowerby,
Eev. Samuel A. Thompson- Yates, M.A.

were elected Members of the Eoyal Institution.

The Special Thanks of the Members were returned for the
following Donation to the Fund for the Promotion of Experimental
Eesearch at Low Temperatures : —

The Duke of Northumberland, K.G. .. £200

The Special Thanks of the Members were returned to Colonel
Coleridge Grove for a Bust of his father, the late Sir William Grove,
M.B.I, and also to Professor Dewar for a Marble Pedestal for the
Bust.

The following Lecture arrangements were announced : —

Christmas Lectures.
Professor Silvanus P. Thosipson, D.Sc. F.K.S. M.R.L Six Lectures
(adapted to a Juvenile Auditory) on Light, Visible and Invisible. On
Dec. 29 {Tuesday), Dec. 31, 1896;' Jan. 2, 5, 7, 9, 1897.

Professor Augustus D. Waller, M.D. F.K.S. FuUerian Professor of Phy-
siology, R.I. Twelve Lectures on Animal Electricity. On Tuesdays, Jan. 19,
26, Feb. 2, 9, 16, 23, March 2, 9, 16, 23, 30, April 6.

Professor Henry A. Mieks, M.A. F.R.S. Three Lectures on Some Secrets
OF Crystals. On Thursdays, Jan. 21, 28, Feb. 4.

J. W. Gregory, Esq. D.Sc. F.G.S. of the British Museum (Natural History).
Three Lectures on The Problems of Arctic Geology. On Thursdays, Feb. 11,
18, 25.

Professor Percy Gardner, Litt.D. F.S.A. Professor of Classical ArchsBology
and Art in the University of Oxford. Three Lectures on Greek History and
Extant Monuments. On Thursdays, March 4, 11, 18.

Professor W. Boyd Dawkins, M.A. F.R.S. F.S.A. F.G.S. Three Lectures
on The Rei-ation of Geology to History. 1. The Incoming of Man. 2. The
Frontier of History in Britain. 3. Roman Britain. On Thursdays, March 25,
April 1, 8.

Vol. XV. (No. 90.) u

290 General Monthly Meeting. [Dec. 7,

Carl Armbruster, Esq. Three Lectures on Neglected Italian and
French Composers (with Musical Illustrations). Oa Saturdays, Jan. 23, 30.
Feb. 6.

Walter Feewen Lord, Esq. Three Lectures on The Growth of the
Mediterranean Route to the East. On Saturdays, Feb. 13, 20, 27.

The Right Hon. Lord Rayleigh, M.A. D.C.L. LL.D. F.R.S. M.R.I. Pro-
fessor of Natural Philosophy, R.I. Six Lectures on Electricity and Electrical
Vibrations. On Saturdays, March 6, 13, 20, 27, April 3, 10.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

prom

The French Government — Documents Inedits sur I'histoire de France. Comptes
des Batiments du Roi sous le regne de Louis XIV. publics par M. J. Guiflfrey.
Tome IV. 1696-1705. 8vo. 1896.
Accademia dei Lincei, Eeale, Roma — Classe di Scienze Fisiche, Matematiche e
Naturali. Atti, Serie Quinta : Rendiconti. 2«* Semestre, Vol. V. Fasc. 8-9.
Classe di Scienze Morali, &c. Serie Quinta, Vol. V. Fasc. 10. 8vo. 1896.
American Geographical Society — Bulletin, Vol. XXVIII. No. 3. 8vo. 1896.
Asiatic Society Royal (Bombay Branch) — Journal, Vol. XIX. No. 52. 8vo. 1896.
Astronomical Society, Royal — Monthly Notices, Vol. LVI. No. 10. 8vo. 1896.
Bankers, Institute o/— Journal, Vol. XVII. Part 8. 8vo. 1896.
Bimetallic League — Papers on Bimetallism, &c. 8vo. 1896.
Blitz, Professor (the Author) — On Vaccination. 8vo. 1896.
Boston Public Library —'Monihlj Bulletin, Vol. I. No. 9. 8vo. 1896.
British Architects, Royal Institute of — Journal, 3rd Series, Vol. IV. Nos. 1-3.

4to. 1896.
British Astronomical Association — Journal, Vol. VII. No. 1. 8vo. 1896.
Camera Club — Journal for Nov. 1896. 8vo.
Canada, Geological Survey of — Annual Report, New Series, Vol. VII. 1894. 8vo.

And Maps to Vol. VII. fol. 1896.
Canadian Institute — Transactions, Vol. V. Part I. No. 9. 8vo. 1896.
Cawston, George, Esq. (the Author) — The Early Chartered Companies. 8vo. 1896.
Chemical Industry, Society of — Journal, Vol. XV. No. 10. 8vo. 1896.
Chemical Society— Journal for Nov. 1896. 8vo.

Proceedings, Nos. 169, 170. 8vo. 1896.
Cracovie, Academie des Sciences — Bulletin, 1896, No. 8. 8vo.
Dax, Socie'te de i?or(?a— Bulletin, 1896, 2® Trimestre. 8vo.

East India Association — Journal, New Series, Vol. XXVIII. No. 7. 8vo. 1896.
Editors — American Journal of Science for Nov. 1896. 8vo.

Analyst for Nov. 1896. 8vo.

Anthony's Photographic Bulletin for Nov. 1896. 8vo.

Astrophysical Journal for Nov. 1896. 8vo.

Athenaeum for Nov. 1896. 4to.

Author for Dec. 1896. 8vo.

Bimetallist for Nov. 1896.

Chemical News for Nov. 1896. 4to.

Chemist and Druggist for Nov. 1896. 8vo.

Education for Nov. 1896.

Electrical Engineer for Nov. 1896. fol.

Electrical Engineering for Nov. 1896. 8vo.

Electrical Review for Nov. 1896. 8vo.

Electricity for Nov. 1896. 8vo.

Engineer for Nov. 1896. fol.

Engineering for Nov. 1896. fol.

Homoeopathic Review for Nov. 1896. 8vo.

Horological Journal for Nov.-Dec. 1896. 8vo.

1896.J General Monthly Meeting. 291

Editors — continued.
Industries and Iron for Nov. 1896. fol.
Invention for Nov. 1896.
Journal of Physical Chemistry for Nov. 1896.
Law Journal for Nov. 1896. 8vo.
Life-Boat Journal for Nov. 1896. 8vo.
Lightning for Nov. 1896. 8vo.

London Technical Education Gazette for Nov. 1896. 8vo.
Machinery Market for Nov.-Dec. 1896. 8vo.
Nature for Nov. 1896. 4to.
New Church Magazine for Dec. 1896. 8vo.
Nuovo Cimento for Sept. 1896. 8vo.
Photographic News for Nov. 1896. 8vo.
Physical Review for Nov.-Dec. 1896. 8vo.
Science Sif tings for Nov. 1896.
Transport for Nov. 1896. fol.
Tropical Agriculturist for Nov. 1896.
Zoophilist for Nov. 1896. 4to.
Essex, County Technical Laboratories — Journal of the Essex Technical Labora-
tories for October 1896. 8vo.
Florence, Bihlioteca Nazionale Cen^raZe— Bolletino, Nos. 260-262. 8vo. 1896.
Franldin Institute — Journal for Nov. 1896. 8vo.

GeograpJiical Society, Royal — Geographical Journal for Nov. 1896. 8vo.
Geological Society — Quarterly Journal, No. 208. 8vo. 1896.
Haarlem, Musee Teyler— Archives, Serie II. Vol. V. Part 2. 8vo. 1896.
Head, Jeremiah, Esq. M.Inst.C.E. M.B.I. {the Author) — American and English
Metliods of Manufacturing Steel Plates. 8vo. 1896. (Inst. Civil Eng.
Reprint.)
Historical Society, i2o?/aZ— Transactions, N.S. Vol. X. 8vo. 1896.
Index of Archaeological Papers published in 1894. 8vo. 1896.
Report on a Photographic Survey of England and Wales. 8vo. 1895.
Forms of Schedule for an Ethnographical Survey of United Kingdom. 8vo. 1895.
Imperial Institute — Imperial Institute Journal for Nov. 1896.
Johns Hopkins University — American Chemical Journal, Vol. XVIII. No. 9. 8vo.

1896.
Leipzig, Fiirstlich JaUonowshische Gesellschaft — Preisschriften, Nos. 32, 33. 8vo.

1896.
Linnean Society — Proceedings, Nov. 1895 to June 1896. 8vo.

Journal, Nos. 164, 218, 220-227. 8vo. 1896.
Macintosh, Professor W. C. LL.B. F.R.S. (the Author)— The Gatty Marine
Laboratory and the steps which led to its foundation in the University of
St. Andrews. (With Bibliography of Marine Zoology.) 8vo. 1896.
Manchester Free Libraries Committee — Forty-fourth Annual Report. 8vo.

1895-96.
Manchester Geological Society — Transactions, Vol. XXIV. Part 10. 8vo. 1896.
Manchester Literary and Philosophiccd Society — Complete List of Members, &c.
and Bibliographical Lists of MSS. vols, and of Memoirs, &c. 8vo. 1896.
Memoirs and Proceedings, Vol. XLI. Part 1. 8vo. 1896.
Meteorological Society — Quarterly Journal, No. 100. 8vo. 1896.

Meteorological Record, No. 61. 8vo. 1896.
Mining Engineers, Federated Institution of — Report of the Proceedings of the
Conference on Inland Navigation (1895), with Map of English Canals. 8vo,
1895.
Navy League — Navy League Journal for Nov. 1896. 8vo.
Neio South Wales, Royal Society o/*— Journal and Proceedings, Vol. XXIX. (1895).

8vo. 1896.
Numismatic Society — Numismatic Chronicle and Journal, 1896, Part 3. 8vo.
Odontological Society of Great Britain — Transactions, Vol. XXIX. No. 1. 8vo.
1896.

292 General Monthly Meeting. [Dec. 7, 1896.

Onnes, D. E. K — Communications from the Laboratory of Physics at the Univer-
sity of Leiden, Nos. 24, 26, 28-31. 8vo. 1896.
Paris, Societe Francaise de Physique — Bulletin, No. 86. 8vo. 1896.
Pharmaceutical Society of Great Britain — Journal for Nov. 1896. 8vo.
Photographic Society, Royal — Photographic Journal for Oct.-Nov. 1896. 8vo.
Physical Society of London — Proceedings, Vol. XIV. Part 11. 8vo. 1896.
Bochechoziart, La Societe les Amis des Sciences et Arts — Bulletin, Tome VI.

Nos. 1, 2. 8vo. 1896.
Rome, Ministry of Public Worhs — Giomale del Genio Civile, 1896, Fasc. 6, 7.

And Designi. fol.
Royal Society of London — Proceedings, No. 362. 8vo. 1896.

Philosophical Transactions, Vol. CLXXXVII. A. Nos. 183, 184. 4to. 1896.
Selhorne Society — Nature Notes for Nov. 1896. 8vo.
Sheriff-Bain, Miss W. — Papers by Professor Bickerton op a New Astronomic

Theory, &c.
Society of Arts — Journal for Nov. 1896. 8vo.

St. Bartholomew's Hospital— Statistical Tables for 1895. 8vo. 1896.
United Service Institution, Royal — Journal, No. 225. 8vo. 1896.
United States Department of Agriculture — Monthly Weather Review for July
and August, 1896. 8vo.
Experiment Station Record, Vol. VIII. No. 1. 8vo. 1896.
Vienna, Imperial Geological Institute—YeThandlungen, 1896, Nos. 10-12. 8vo.
Jahrbuch, Band XLV. Heft 2-4 ; Band XLVI. Heft 1. 8vo. 1896.
Abhandlungen, Band XVIII. Heft 1. 4to. 1895.
Zurich, Naturforschende Gesellschaft — Festschrift 1746-1896 (History of the
Society). 2 vols. 8vo. 1896.

IS opal Institution of (great Britanu

WEEKLY EVENING MEETING,

Friday, January 29, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer
and Vice-President, in the Chair.

Professor Jagadis Chunder Bose, M.A. D.Sc.
Professor of Physics in the Presidency College, Calcutta.

Electro-Magnetic Badiation and the Polarisation of the Electric Bay.

The great work of Hertz in verifying the anticipations of Maxwell
has been followed in this country by many important investigations
on Electric Waves. The Royal Institution witnessed the repetition of
some of the brilliant experiments of Professors Fitzgerald and Lodge.
My interest in the subject, and inspiration for work, are to a great
extent derived from the memorable addresses delivered in this hall,
and I am glad to have an opportunity to lay before you, at this very
same place, an account of some work I have been able to carry out.

As the subject of ether waves produced by periodic electric disturb-
ances is to be dealt with in this lecture, a few models exhibiting the
production of material waves by periodic mechanical disturbances may
be of interest. A pendulum swings backwards and forwards at regular
intervals of time ; so does an elastic spring when bent and suddenly
released. These periodic strokes produce waves in the surrounding
medium ; the aerial waves striking the ear may, under certain condi-
tions, produce the sensation of sound. The necessary condition for
audibility is, that the frequency of vibration should lie within certain
limits.

As the air is invisible, we cannot see the waves that are produced.
Here is a model in which the medium is thrown into visible waves by
the action of periodic disturbances. The beaded string representing
the medium is connected at its lower end with a revolving electric
motor. The rotation of the motor is periodic; observe how the
periodic rotation throws the string into wave forms ; how these waves
carry energy from the source to a distant place ; how a suitable re-
ceiver, a bell for example, is made to respond. I now produce quicker
rotation by sending a stronger current through the motor ; the
frequency or pitch is raised, and the waves formed are seen to become
shorter. By means of the attached counter, the different frequencies
are determined.

Here is a second model, a spiral spring, attached to which is a

thin string. As the string is pulled, the spring is strained more and

more, till the thread suddenly breaks. The spring, suddenly released,

is seen to oscillate up and down. Electric vibration is produced in

Vol. XV, (No. 91.) x

294

Professor Jagadis Chunder Bose

[Jan. 29,

Fig. 1.— Mechanical Wave Apparatus.
(The current regulating the speed of rota-
tion is varied by an interposed rheostat.
The counter is at the top.)

a somewhat similar way. If
two metallic^ spheres be
strongly charged with oppo-
site electrifications, the me-
dium is electrically strained,
and when this strain is sud-
denly removed by a discharge,
waves are produced in the
medium. The discharge is
oscillatory, consisting of back-
ward and forward rushes of
electricity ; positive electricity
flowing now in one direction,
and immediately afterwards in
an opposite direction. These
rapid alternate flows, giving
rise to ether vibration, may be
illustrated by a modification
of the well-known Cartesian
diver experiment. By means
of a bulb and connecting tube,
alternate compression and
rarefaction may be produced
in the cylinder, attended with
alternate rushes of air-currents
through the connecting tube.
These give rise to oscillation
of the immersed ball.

By oscillatory electric dis-
charge, waves are produced in
the ether. To produce oscil-
latory discharge. Hertz used
plates or rods with sparking
balls at the ends. He found
that the sparks ceased to be
oscillatory as soon as the sur-
face of the sparking balls got
roughened ; there was then a
leak of electricity, and no
sudden discharge. The balls
had to be taken out every now
and then for repolishing, and
the process was tedious in the
extreme. Prof. Lodge made
the important discovery that if
two side balls were made to
spark into an interposed third
ball, the oscillatory nature of
the discharge was not affected

1897.] on the Polarisation of the Electric Bay. 295

to so great an extent by a change in tlie nature of the surface. But even
here the disintegration of the sparking surface produced by a torrent
of sparks soon puts an end to oscillation. I found this difficulty
removed to a great extent by making the balls of platinum, which
resists the disintegrating action. I also found that it was not at all
necessary to have a series of useless sparks, which ultimately spoils the
efficiency of the radiator and makes its action uncertain. A flash
of radiation for an experiment is obtained from a single spark, and
for a series of experiments one does not require more than fifty or a
hundred sparks, which do not in any way affect the radiator. As
an electric generator I use a small and modified form of Ruhmkorff's
coil, actuated by a single storage cell. A spark is produced by a short
contact and subsequent break of a tapping key. With these modi-
fications one of the most troublesome sources of uncertainty is
removed. The coil and the cell are inclosed in a small double-
walled metallic box, with a tube for the passage of the electric beam.
The magnetic variation due to the make and break of the primary
of the Ruhmkorff's coil, disturbs the receiver. This difficulty is
removed by making the inner box of soft iron, which acts as a
magnetic screen.

A few words may here be said about the necessary conditions to
be kept in view in making an electric wave apparatus an instrument
of precision. If one merely wishes to produce response in a receiver
at a distance, the more energetic the vibration is, the more likely
it is to overcome obstacles. The waves may with advantage be of
large size, as they possess very great penetrative power. The
surface or the depth of the sensitive layer in the receiver may be
extended, for if one part of it does not respond another part will. But
for experimental investigations the conditions to be fulfilled are quite
different. Too great an intensity of radiation makes it almost impos-
sible to prevent the disturbance due to stray radiation. As the waves
are invisible, it is difficult to know through what unguarded points they
are escaping. They may be reflected from the walls of the room or
the person of the experimenter, and falling on the receiver disturb it.

The radiation falling on any portion of the receiving circuit — the
leading wires or the galvanometer — disturbs the delicate receiver.
It is extremely difficult to shield the receiving circuit from the dis-
turbing action of stray radiation. These difficulties were, however,
successfully removed by the use of short electric waves. With these,
it is not at all necessary to take special precautions to shield either
the galvanometer or the leading wires, the sensitive layer in the
receiver alone being affected by the radiation. The bare leading
wires may be exposed in close proximity to the source of radiation,
and yet no disturbance is produced.

For experimental investigations it is also necessary to have a narrow
pencil of electric radiation, and this is very difficult to obtain, unless
waves of very short length are used. With large waves diverging
in all directions and curling round corners, all attempt at accurate
work is futile. For angular measurements it is necessary to direct

X 2

296 Professor Jagadis Chunder Bose [Jan. 29,

the electric beam in the given direction along narrow tubes, and
receive it in another tube in which is placed the receiver. The waves
experience great difficulty in passing through narrow apertures, and
there are other troubles from the interference of direct and reflected
waves. These difficulties were ultimately overcome by making suitable
radiators emitting very short waves ; the three radiators here ex-
hibited, give rise to waves which are approximately ^ inch, ^ inch
and 1 inch in length. The intensity of emitted radiation is mode-
rately strong, and this is an advantage in many cases. It sometimes
becomes necessary to have a greater intensity without the attendant
trouble inseparable from too long waves. I have been able to secure
this by making a new radiator, where the oscillatory discharge takes
place between two circular plates and an interposed platinum ball.
The sparking takes place at right angles to the circular j^lates. The
intensity of radiation is by this expedient very greatly increased.
The parallel pencil of electric radiation, used in many of the experi-
ments to be described below, is only about half an inch in diameter.
The production of such a narrow pencil became absolutely necessary
for a certain class of investigations. Merely qualitative results for
reflection or refraction may no doubt be obtained with gigantic
mirrors or prisms, but when we come to study the phenomena of
polarisation as exhibited by crystals. Nature imposes a limit, and this
limitation of the size of the crystals has to be accepted in conducting
any investigation on their polarising properties.

The greatest drawback, however, in conducting experimental
investigations with electric radiation arises from the difficulty of
constructing a satisfactory receiver for detecting these waves. For
this purpose I at first used the original form of coherer made of
metallic filings as devised by Professor Lodge. It is a very delicate
detector for electric radiation, but unfortunately I found its indica-
tions often to be extremely capricious.

The conditions for a satisfactory receiver are the following : —

(1) Its indications should always be reliable.

(2) Its sensitiveness should remain fairly uniform during the
experiment.

(3) The sensibility should be capable of variation, to suit difierent
experiments.

(4) The receiver should be of small size, and preferably linear,
to enable angular measurements to be taken with accuracy.

These conditions seemed at first almost impossible to be attained.
The coherer sometimes would be so abnormally sensitive that it
would react without any apparent cause. At other times, when
acting in an admirable manner, the sensitiveness would suddenly
disappear at the most tantalising moment. It was a most dreary
experience when the radiator and the receiver failed by turns, and it
was impossible to find out which was really at fault.

From a series of experiments carried out to find the causes which
may affect prejudicially the action of the receiver, I was led to sup-

1897.] on tJie Polarisation of the Electric Bay. 297

pose that the uncertainty in the response of the receiver is probably
due to the following : —

(1) Some of the particles of the coherer might be too loosely
applied against each other, whereas others, on the contrary, might be
jammed together, preventing proper response.

(2) The loss of sensibility might also be due to the fatigue pro-
duced on the contact surfaces by the prolonged action of radiation.

(3) As the radiation was almost entirely absorbed by the outer-
most layer, the inner mass, which acted as a short circuit, was not
necessary.

For these reasons I modified the receiver into a spiral-spring
form. Fine metallic wires (generally steel, occasionally others,
or a combination of different metals) were wound in narrow spirals
and laid in a single layer on a groove cut in ebonite, so that
the spirals could roll on a smooth surface. The ridges of the
contiguous spirals made numerous and well-defi.ned contacts, about
one thousand in number. The useless conducting mass was thus
abolished, and the resistance of the receiving circuit almost entirely
concentrated at the sensitive contact surface exposed to radiation. If
any change of resistance, however slight, took place at the sensitive
layers, the galvanometer in circuit would show strong indications.
The pressure throughout the mass was made uniform as each
spring transmitted the pressure to the next. When the contact
surfaces had too long been acted on, fresh surfaces could easily be
brought into contact by the simultaneous rolling of all the spirals.

The sensibility of the receiver to a given radiation, I found,
depends (1) on the pressure to which the spirals are subjected, and
(2) on the E.M.F. acting on the circuit. The pressure on the spirals
may be adjusted, as will be described later on, by means of a fine
screw. The E.M.F. is varied by a potentiometer-slide arrangement.
This is a matter of great importance, as I often found a receiver,
otherwise in good condition, failing to respond when the E.M.F.
varied slightly from the proper value. The receiver, when subjected
to radiation, undergoes exhaustion. The sensibility can, however,
be maintained fairly uniform by slightly varying the E.M.F. to keep
pace with the fatigue produced.

The receiving circuit thus consists of a spiral-spring coherer,
in series with a voltaic cell and a dead-beat galvanometer. The
receiver is made by cutting a narrow groove in a rectangular piece
of ebonite, and filling the groove with bits of coiled spirals arranged
side by side in a single layer. The spirals are prevented from falling
by a glass slide in front. They are placed between two pieces
of brass, of which the upper one is sliding and the lower one fixed.
These two pieces are in connection with two projecting metallic rods,
which serve as electrodes. An electric current enters along the
breadth of the toj) spiral and leaves by the lowest spiral, having
to traverse the intermediate s^)irals along the numerous points of
contact. When electric radiaticJn ic, absorbed by the sensitive sur-

298 Professor Jagadis Chunder Bose [Jan. 29,

face, there is a sudden diminution of the resistance, and the galvano-
meter spot is violently deflected.

By means of a very fine screw the upper sliding piece can be
gently pushed in or out. In this way the spirals may be very
gradually compressed, and the resistance of the receiver diminished.
The galvanometer spot can thus easily be brought to any convenient
position on the scale. "When electric radiation falls on the sensitive
surface the spot is deflected. By a slight unscrewing the resistance
is increased, and the spot made to return to its old position. The
receiver is thus re-sensitised for the next experiment.

The receiver thus constructed is perfectly reliable ; the sensibility
can be widely varied to suit different experiments, and this sensibility
maintained fairly uniform. When necessary, the sensitiveness can
be exalted to almost any extent, and it is thus possible to carry out
some of the most delicate experiments (specially on polarisation) with
certainty.

The main difficulties being thus removed, I attempted to construct
a complete electric wave apparatus, which would be portable, with
which all the experiments on electric radiation could be carried out
with almost as great an ease and certainty as corresponding experi-
ments on light, and which would enable one to obtain even quantita-
tive results with fair accuracy.

The complete apparatus is here exhibited ; all its different parts,
including the galvanometer, and all the accessories for reflection,
refraction, polarisation, and other experiments, are contained in a
small case only 2 feet in length, 1 foot in height and 1 foot in
breadth. The apparatus can be set up in a few minutes, the various
adjustments requiring only a short time.

The radiating apparatus is 6 by 5 by 3 inches, the size of a
small lantern. It contains the coil and a small storage cell ; the
radiator tube is closed with a thin plate of ebonite to prevent deposit
of dust on the radiator. One charge of the cell stores enough
energy for experiments to be carried out for nearly a month. It is
always ready for use and requires very little attention. A flash of
radiation for an experiment is produced by a single tap and break
of the interrupting key.

The radiating apparatus and the receiver are mounted on stands
sliding in an optical bench. Experiments are carried out with diver-
gent or parallel beams of electric radiation. To obtain a parallel
beam, a lens of sulphur or glass is mounted in a tube. Suitable
lenses can be constructed from the accurate determination, which
I have been able to make, of the indices of refraction of various
substances for the electric ray, by a method which will be described
later on. This lens-tube fits on the radiator-tube, and is stopped
by a guide when the oscillatory spark is at the principal focus of the
lens. The radiator-tube is further provided with a series of dia-
phragms by which the amount of radiation may be varied.

For experiments requiring angular measurement, a spectrometer-

1897.]

on the Polarisation of the Electric May.

299

circle is mounted on one of the sliding stands. The spectrometer
carries a circular platform, on which the various reflectors, refractors,
&c., are placed. The platform carries an index, and can rotate inde-
pendently of the circle on which it is mounted. The receiver is
carried on a radial arm (provided with an index), and points to the
centre of the circle. An observing telescope may also be used with
a glass objective, and a linear receiver at the focus.

I shall now exhibit some of the principal experiments on electric
radiation.

T ^

Fig. 2. — Arrangement of the Apparatus. One-sixth nat. size.

R, radiator ; T. tapping key ; S, spectrometer-circle ; M, plane mirror ;
C, cylindrical mirror ; p, totally reflecting prism ; P, semi-cylinders ;
K, crystal-holder ; F, collecting funnel attached to the spiral spring
receiver ; t, tangent screw, by which the receiver is rotated ; V, vol-
taic cell ; r, circular rheostat ; G, galvanometer.

Selective Absorption.

I arrange the radiation apparatus so that a parallel beam of elec-
tric radiation proceeding from the lantern falls on the receiver placed
opposite ; the receiver responds energetically, the light-spot from the
galvanometer being swept violently across the screen. I now inter-
pose various substances to find out which of them allow the radiation
to pass through and which do not. A piece of brick, or a block of
pitch, is thus seen to be quite transparent, whereas a thick stratum
of water is almost opaque. A substance is said to be coloured when
it allows light of one kind to pass through, but absorbs light of a
different kind. A block of pitch is o^Daque to visible light, but trans-
parent to electric radiation ; whereas water, which is transparent to
light, is opaque to electric radiation. These substances exhibit selec-
tive absorption, and are therefore coloured.

300 Professor Jagadis Chunder Bose [Jan. 29,

There is an interesting speculation in reference to the possibility
of the sun emitting electric radiation. No such radiation has yet
been detected in sunlight. It may be that the electric rays are ab-
sorbed by the solar or the terrestrial atmosphere. As regards the
latter supposition, the experiment which I am able to exhibit on the
transparency of liquid air may be of interest. Professor Dewar has
kindly lent me this large bulb full of liquid air, which is equivalent
to a great thickness of ordinary air. This thick stratum allows the
radiation to pass through with the greatest facility, proving the high
transparency of the liquid air.

Verification of the Laws of Reflection.

A small plane metallic mirror is mounted on the platform of the
spectrometer-circle. The receiver is mounted on a radial arm. The
law of reflection is easily verified in the usual way. The second
mirror, which is curved, forms an invisible image of the source of
radiation. As I slowly rotate the cylindrical mirror, the invisible
image moves through space ; now it falls on the receiver, and there
is a strong response produced in the receiver.

Refraction.

Deviation of the electric ray by a prism may be shown by a prism
made of sulphur or ebonite. More interesting is the phenomenon of
total reflection. A pair of totally-reflecting prisms may be obtained
by cutting a cube of glass, which may be an ordinary paper-weight,
across a diagonal. The critical angle of a specimen of glass I found
to be 29°, and a right-angled isosceles prism of this material produces
total reflection in a very efficient manner. When the receiver is
placed opposite the radiator, and the prism interposed with one of its
faces perpendicular to the electric beam, there is not the slightest
action on the receiver. On turning the receiver through 90°, the re-
ceiver responds to the totally-reflected ray.

Opacity due to multiple refraction and reflection, analogous to the
opacity of powdered glass to light, is shown by filling a long trough
with irregularly-shaped pieces of pitch, and interposing it between
the radiator and the receiver. The electric ray is unable to pass
through the heterogeneous media, owing to the multiplicity of re-
fractions and reflections, and the receiver remains unaffected. But
on restoring partial homogeneity by pouring in kerosene, which has
about the same refractive index as pitch, the radiation is easily
transmitted.

Determination of the Index of Refraction.

Accurate determination of the indices of refraction becomes im-
portant when lenses have to be constructed for rendering the electric
beam parallel. The index for electric radiation is often very diflierent

1897.]

on the Polarisation of the Electric Bay.

301

from the optical index, and the focal distance of a glass lens for light
gives no clue to its focal distance for electric radiation. I found, for
example, the index of refraction of a specimen of glass to be 2 • 04,
whereas the index of the same specimen for sodium light is only
1-53.

There are again many substances, like the various rocks, wood,
coal-tar, and others, whose indices cannot be determined owing to
their opacity to light. These substances are, however, transparent
to electric radiation, and it is therefore possible to determine their
electric indices. For the determination of the index, the prism-
method is not very suitable. I found the following method, of which
I shall exhibit the optical counterpart, to yield good results. When
light passes from a dense to a light medium, then, at a certain critical
angle, the light is totally reflected, and from the critical angle the
index can be determined. I have here a cylindrical trough filled
with water. Two glass plates inclosing a parallel air-film are sus-
pended vertically across the diameter of the cylinder, dividing the
cylinder into two halves. The cylinder, mounted on a graduated

Fig. 3.
(The dotted lines show the two positions of the air-film for total reflection.)

circle, is adjusted in front of an illuminated slit, an image of the slit
being cast by the water-cylinder on the screen. The divergent beam
from the slit, rendered nearly parallel by the first half of the cylinder,
is incident on the air-film, and is then focussed by the second half of
the cylinder. As the cylinder is slowly rotated, the angle of incidence
at the air-film is gradually increased, but the image on the screen
remains fixed. On continuing the rotation you observe the almost
sudden extinction of the image. I say almost, because the light is not
monochromatic, and the difierent components of white light undergo
total reflection in succession. Just before total extinction the image
you observe is reddish in colour, the violet and the blue lights being
already reflected. On continuing the rotation the image is completely
extinguished. Kotation of the cylinder in an opposite direction gives
another reading for total reflection, and the diff'erence of the two
readings is evidently equal to twice the critical angle.

In a similar way I have been able to determine the indices of re-
fraction of various substances, both solid and liquid, for electric
radiation. In the case of solids, two semi-cylinders, separated by a

302

Professor Jagadis Chunder Bose

[Jan. 29,

suitable parallel air-space, are placed on the spectrometer-circle, the
receiver being placed opposite the radiator. The trouble of following
the deviated ray is thus obviated. The index of refraction of glass I
found to be 2 • 04 ; that of commercial sulphur is 1 • 73.

Double Befraction and Polarisation.

I now proceed to demonstrate some' of the principal phenomena
of polarisation, especially in reference to the polarisation produced
by crystals and other substances, and by dielectrics when subjected
to molecular stress due to pressure or unequal heating.

As the wave-length of electric radiation is many thousand times
the wave-length of light,^there is a misgiving as to whether it would

Fig. 4. — Polarisation Apparatus.

K, crystal-holder; S, a piece of stratified rock; C, a crystal; J, jute
polariser ; W, wire-grating polariser ; D, vertical graduated disc, by
which the rotation is measured.

be possible to exhibit polarisation effects with crystals of ordinary
size. I hope to be able to demonstrate that such a misgiving is
groundless.

A beam of ordinary light incident on a crystal of Iceland spar is
generally bifurcated after transmission, and the two emergent beams
are found polarised in planes at right angles to each other. The
usual optical method of detecting the bi-refringent action of crystal,
is to interpose it between the crossed polariser and analyser. The
interposition of the crystal generally brightens the dark field. This
is the so-called depolarisation effect, and is a delicate test for double-
refracting substances. There is, however, no depolarisation when the

1897.] on the Polarisation of the Electric Bay, 303

principal plane of the crystal coincides with the polarisation planes of
either the polariser or the analyser. The field also remains dark when
the optic axis of the crystal is parallel to the incident ray.

A similar method is adopted for experimenting with polarised
electric radiation.

The spectrometer-circle is removed from the optical bench, and
an ordinary stand for mounting the receiver substituted. By fitting
the lens-tube, the electric beam is made parallel. At the end of the
tube may be fixed either the grating polariser or the jute or serpen-
tine polarisers, to be subsequently described.

The receiver fitted with the analyser is adjusted by a tangent
screw, the rotation of the analyser being measured by means of an
index and a graduated vertical disc.

The polarising gratings may be made, according to Hertz, by
winding copper wires, parallel, round square frames. The polari-
sation apparatus is, however, so extremely delicate, that unless
all the wires are strictly parallel, and the gratings exactly crossed,
there is always a resolved component of radiation which acts on the
sensitive receiver. It is a very difficult and tedious operation to
cross the gratings. I have found it to be a better plan to take two
thick square plates of copper of the same size, and, placing one over
the other, cut a series of slits (which stop short of the edges) parallel
to one of the edges. One of these square pieces serves as a polariser,
and the other as an analyser. When the two square pieces are ad-
justed, face to face, with coincident edges, the gratings must either be
parallel or exactly crossed. Such accurate adjustments make it pos-
sible to carry out some of the most delicate experiments.

The radiator-tube, with the lens and the attached polariser, is
capable of rotation. The emergent beam may thus be polarised in a
vertical or a horizontal plane. The analyser fitted on to the receiver
may also be rotated. The gratings may thus be adjusted in two
positions.

(1) Parallel position.

(2) Crossed position.

In the first position the radiation is transmitted through both the
gratings, falls on the sensitive surface, and the galvanometer responds.
The field is then said to be bright. In the second position the radia-
tion is extinguished by the crossed gratings, the galvanometer re-
mains unaffected, and the field is said to be dark. But in interposing
a double-refracting substance in certain positions between the crossed
gratings, the field is partially restored, and the galvanometer-spot
sweeps across the scale.

I have now the analyser and the polariser exactly crossed, and
there is not the slightest action on the receiver. Observe the great
sensitiveness of the arrangement ; I turn the polariser very slightly
from the crossed position, and the galvanometer-spot is violently
deflected.

304 Professor Jagadis Chunder Bose [Jan. 29,

I now readjust the gratings in a crossed position. I have in my
hand a large block of the crystal beryl ; it is perfectly opaque to
light. I now hold the crystal with its principal plane inclined at
45° between the crossed gratings, and the galvanometer-spot, hitherto
quiescent, sweeps across the scale. It is very curious to observe the
restoration of the extinguished field of electric radiation, itself in-
visible, by the interposition of what appears to the eye to be a per-
fectly opaque block of crystal. If the crystal is slowly rotated, there
is no action on the receiver when the principal plane of the crystal
is parallel to either the polariser or the analyser. Thus, during one
complete rotation there are four positions of the crystal when no
depolarisation effect is produced.

Eotation of the crystal, when held with its optic axis parallel to
the incident ray, produces no action. The field remains dark.

Here is another large crystal, idocrase, belonging to the ortho-
rhombic system, which shows the same action. It is not at all
necessary to have large crystals ; a piece of calc-spar, taken out of an
optical instrument, will polarise the electric ray. But the effect pro-
duced by the crystal epidote seems extraordinary. I have here a
piece with a thickness of only • 7 cm. — a fraction of the wave-length
of the electric radiation — and yet observe how strong is its depolaris-
ing effect.

I subjoin a representative list of crystals belonging to the different
systems, which would be found to produce double refraction of the
electric ray.

Tetragonal System. — Idocrase, scapolite.

OrtTiorliomhic System. — Barytes, celestine, cryolite, andalusite,
hypersthene.

Hexagonal System. — Calcite, apatite, quartz, beryl, tourmaline.

Monoclinic System. — Selenite, orthoclase, epidote.

Triclinic System. — Labradorite, microcline, amblygonite.

Douhle Refraction produced by a Strained Dielectric.

Effect due to Pressure. — A piece of glass, when strongly com-
pressed, becomes double refracting for light. An analogous experi-
ment may be shown with electric radiation. Instead of producing
pressure artificially, it seemed to me that stratified rocks, which, from
the nature of their formation, were subjected to great pressure, would
serve well for my experiment. Here is a piece of slate about an inch
in thickness. I interpose this piece with the plane of stratification
inclined at 45°, and the spot of light flies off the scale. I now care-
fully rotate the piece of slate ; there is no depolarisation effect when
the plane of stratification is parallel to either the polariser or the
analyser. Thus the existence of strain inside an opaque mass can
easily be detected, and what is more, the directions of maximum and
minimum pressures can be determined with great exactitude.

Effect due to Strains in Cooling. — An effect similar to that pro-

1897.] on the Polarisation of the Electric Bay. 305

duced by unannealed glass may be sbown by this piece of solid
paraffin, wbicb was cast in a mould, and chilled unequally by a freez-
ing mixture. One of these blocks was cast two years ago, and it has
still retained its unannealed property. This effect may even be
shown without any special preparation. Pieces of glass or ebonite,
too, are often found sufficiently strained to exhibit double refraction.

Phenomena of Double Absorption.

Being desirous of making a crystal polariser, I naturally turned
*to tourmaline, but was disappointed to find it utterly unsuitable as
a polariser. There is a difference in transparency in directions
parallel and perpendicular to the length, but even a considerable
thickness of the crystal does not completely absorb one of the two
rays. Because visible light is polarised by absorption by tourma-
line, it does not follow that all kinds of radiation would be so
polarised. The failure of tourmaline to polarise the Rontgen rays
is therefore not unexpected, supposing such rays to be capable of
polarisation.

It was a long time before I could discover crystals which acted
as electric tourmalines. In the meanwhile I found many natural
substances which produced polarisation by selective unilateral ab-
sorption. For example, I found locks of human hair to polarise the
electric ray. I have here two bundles of hair ; I interpose one
at 45°, and you observe the depolarisation effect. The darker
specimen seems to be the more efficient. Turning to other substances
more easily accessible, I found vegetable fibres to be good polarisers.
Among these may be mentioned the fibres of aloes (^Agave), rhea
(Boehmeria nivea), pine-apple [Ananas sativus), plantain (3Iusa para-
disiaca). Common jute [Corchorus capsularis) exhibits the property
of polarisation in a very marked degree. I cut fibres of this material
about 3 cm. in length, and built with them a cell with all the fibres
parallel. I subjected this cell to a strong pressure under a press.

1 thus obtained a compact cell 3 cm. by 3 cm. in area, and 5 cm. in
thickness. This was mounted in a metallic case, with two openings

2 cm. by 2 cm. on opposite sides for the passage of radiation. This
cell absorbs vibrations parallel to the length of the fibres, and trans-
mits those perpendicular to the length. Two such cells could thus
be used, one as a polariser and the other as an analyser.

Turning to crystals, I found a large number of them exhibiting
selective absorption in one direction. Of these nemalite and cryso-
tile exhibit this property to a remarkable extent. Nemalite is a
fibrous variety of brucite ; crysotile being a variety of serpentine.
The direction of absorption in these cases is parallel to the length,
the direction of transmission being perpendicular to the length. I
have here a piece of crysotile, only one inch in thickness. I adjust
the polariser and the analyser parallel, and interpose the crysotile
with its length parallel to the electric vibration. You observe that

306 Professor Jagadis Chunder Bose [Jan. 29,

the radiation is completely absorbed, none being transmitted. I now
hold the piece with its length perpendicular to the electric vibration ;
the radiation is now copiously transmitted. Crysotile is thus seen
to act as a perfect electric tourmaline.

Anisotropic Conductivity exhibited by certain Polarising Substances,

In a polarising grating, the electric vibrations perpendicular to
the bars of the grating are alone transmitted, the vibrations parallel
to the grating being absorbed or reflected. In a grating we have a
structure which is not isotropic, for the electric conductivity parallel
to the bars is very great, whereas the conductivity across the bars
(owing to the interruptioDS due to spaces) is almost nothing. We
may, therefore, expect electric vibrations parallel to the bars to pro-
duce local induction currents, which would ultimately be dissipated
as heat. There would thus be no transmission of vibrations parallel
to the grating, all such vibrations being absorbed. But owing to the
break of metallic continuity, no induction current can take place
across the grating ; the vibrations in this direction are, therefore,
transmitted. From these considerations we see how non-polarised
vibrations falling on a grating would have the vibration components
parallel to the direction of maximum conductivity absorbed, and those
in the direction of least conductivity transmitted in a polarised con-
dition.

I have shown that nemalite and crysotile polarise by selective
absorption, the vibration perpendicular to their length being trans-
mitted, and those parallel to their length being absorbed. Bearing
in mind the relation between the double conductivity and double
absorption, as exhibited by gratings, I was led to investigate whether
the directions of the greatest and least absorptions in nemalite and
crysotile were also the directions of maximum and minimum conduc-
tivities respectively. I found the conductivity of a specimen of
nemalite in the direction of absorption to be about fourteen times the
conductivity in the direction of transmission. In crysotile, too, the
directions of the greatest and least absorption were also the directions
of maximum and minimum conductivities.

It must, however, be noted that the substances mentioned above
are bad conductors, and the difference of conductivity in the two
directions is not anything like what we get in polarising gratings. A
thin layer of nemalite or crysotile will, therefore, be unable to pro-
duce complete polarisation. But by the cumulative effect of many
such layers in a thick piece, the vibrations which are perpendicular
to the direction of maximum conductivity are alone transmitted, the
emergent beam being thus completely polarised.

' A double-conducting structure will thus be seen to act as a polariser.
I have here an artificial electric tourmaline, made of a bundle of parallel
capillary glass fibres. The capillaries have been filled with dilute
copper sulphate solution. A simple, and certainly the most handy,

1897.] on the Polarisation of the Electric Bay. 307

polariser is one's outstretched fingers. I interpose my fingers at 45°
between the crossed polariser and the analyser, and you observe the
immediate restoration of the extinguished field of radiation. The
double-conducting nature of the structure is here quite evident.

While repeating these experiments I happened to have by me this
old copy of ' Bradshaw,' and it struck me that here v^^as an excellent
double-conducting structure which ought to polarise the electric ray.
For looking at the edge of the book we see the paper continuous in
one direction along the pages, whereas this continuity is broken across
the pages by the interposed air-films. I shall now demonstrate the
extraordinary efiiciency of this book as an electric polariser. I hold
it at 45° between the crossed gratings, and you observe the strong
depolarisation effect produced. I now arrange the polariser and the
analyser in a parallel position, and interpose the ' Bradshaw ' with
its edge parallel to the electric vibration ; there is not the slightest
action in the receiver, the book held in this particular direction being
perfectly opaque to electric radiation. But on turning it round
through 90°, the ' Bradshaw,' usually so opaque, becomes quite trans-
parent, as is indicated by the violent deflection of the galvanometer-
spot of light. An ordinary book is thus seen to act as a perfect
polariser of the electric ray ; the vibrations parallel to the pages are
completely absorbed, and those at right angles transmitted in a
perfectly polarised condition.

The electric radiation is thus seen to be reflected, refracted and
polarised just in the same way as light is reflected, refracted and
polarised. The two phenomena are identical. The anticipations of
Maxwell have thus been verified by the great work of Hertz and his
successors.

By pressing the key of this radiation apparatus I am able to pro-
duce ether vibrations, 30,000 millions in one second. A second stop
in connection with another apparatus will give rise to a diflerent
vibration. Imagine a large electric organ provided with a very large
number of stops, each key giving rise to a particular ether note.
Imagine the lowest key producing one vibration in a second. W&
should then get a gigantic ether wave 186,000 miles long, Let the
next key give rise to two vibrations in a second, and let each succeed-
ing key produce higher and higher notes. Imagine an unseen hand
pressing the different keys in rapid succession. The ether notes will
thus rise in frequency from one vibration in a second, to tens, to
hundreds, to thousands, to hundreds of thousands, to millions, to
millions of millions. While the ethereal sea in which we are all
immersed is being thus agitated by these multitudinous waves, we
shall remain entirely unaffected, for we possess no organs of percep-
tion to respond to these waves. As the ether note rises still higher
in pitch, we shall for a brief moment perceive a sensation of warmth.
As the note still rises higher, our eye will begin to be affected, a red
glimmer of light will be the first to make its appearance. From
this point the few colours we see are comprised within a single octave

308 Pro/. Bose on the Polarisation of the Electric Ray. [Jan. 29,

of vibration — from about 400 to 800 billions in one second. As the
frequency of vibration rises still higher, our organs of perception fail
us completely ; a great gap in our consciousness obliterates the rest.
The brief flash of light is succeeded ^by unbroken darkness.

These great regions of invisible lights are now being slowly and
patiently explored. In time the great gaps which now exist will be
filled up, and light-gleams, visible and invisible, will be found merg-
ing one into the other in unbroken sequence.

Before I conclude I may be permitted to express my sincere
thanks to the managers of the Eoyal Institution for according me the
privilege of addressing you this evening. I cannot sufficiently ex-
press my gratefulness for all the kindness I have received in this
country. When the managers of this Institution, which has done so
much to advance the cause of Science and Arts, invited me here, I
felt that the scope of this great Institution was not merely confined to
these shores, but embraced other countries, even the most distant.
The land from which I come did at one time strive to extend human
knowledge, but that was many centuries ago ; a dark age has since
supervened. It is now the privilege of the West to lead in this work.
I would fain hope, and I am sure I am echoing your sentiments, that
a time may come when the East, too, will take her part in this
glorious undertaking ; and that at no distant time it shall neither be
the West nor the East, but both the East and the West, that will
work together, each taking her share in extending the boundaries of
knowledge, and bringing out the manifold blessings that follow in its
train.

[J. C. B.]

1897.] General Montldy Meeting. 309

GENERAL MONTHLY MEETING.

Monday, February 1, 1897.

Sir James Criohton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair. \

Alfred Louis Cohen, Esq.

Mrs. Delaforce,

Sir Charles A. Elliott, K.C.S.L LL.D.

John Lawson Johnston, Esq.

Dr. A. Liebmann,

T. George Longstaff, Esq.

Howard Marsh, Esq. F.R.C.S.

Rev. Edward G. C. Parr, M.A.

Charles Rose, Esq.

Edward P. Thompson, Esq.

were elected Members of the Royal Institution.

The Special Thanks of the Members were returned for the
following Donation to the Fund for the Promotion of Experimental
Research at Low Temperatures : —

J. Wolfe Barry, Esq. C.B. .. £25

Sir Frederick Abel, Bart. K.C.B. £50

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

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1897.] General Monthly Meeting. 311

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Mathematisch-PhysiscluB Classe— Abhandlungen, Band XXIII. Nos. 4, 5. 8vo.

1896.
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1897.] The Picturesque in History. 313

WEEKLY EVENING MEETING,

Friday, February, 5, 1897.

The Eight Hon. Lord Halsburt, M.A. D.C.L. F.R.S.

Lord Chancellor, in the Chair.

The Right Rev. The Lord Bishop of London.
Tlie Picturesque in History.

It is an old controversy whether history is a branch of literature
or a branch of science ; but there is no reason why the contro-
versy should ever be decided. A book is written ; it must take its
chance. It is cast upon the world to exercise such influence as it
can, to teach or to attract, to mould thought or to create interest, to
solve questions or to suggest them. There is always one consoling
reflection for authors, which ought to save them from disappointment.
The deeper the impression which a book produces, the smaller is the
circle of its readers likely to be. The general public likes to take
its journeys by easy stages, and will not be carried too far all at once.
Only a select few will be ready to undertake a serious expedition ;
but they are the explorers, and through their eflforts knowledge will
ultimately grow. When pioneers have entered upon a new field, it
takes some time before the communications are made which make
travelling easy. Meanwhile, ideas and notions float disjointedly
into the general stock of knowledge, and afi'ect public opinion
insensibly in various ways. Knowledge of the past is of value as it
affords a background against which men view the present. It is of
some value, as likely to affect men's judgment of what is going on
around them, that ihey should feel that there has been a past at all.
Every additional item of knowledge about the process by which
human society has slowly reached its present form is of increasing
value. From whatever source it comes to them, it is so much to the
good. History is to be welcomed, whatever form it assumes.

There can be no doubt that in late years there has been a very
decided increase of general interest in history amongst us. The nature
of political questions, and the tendency of thought about social
questions, have given a decided impulse in this direction. In small
towns and villages historical subjects are amongst the most popular
for lectures; and historical allusions are acceptable to all audieoces.
It was not so fifteen years ago. At that time I remember an eminent
statesman speaking to me sadly of his experience. He had been
speaking to a vast audience in the open air, under the shadow of one

314 The Bight Bev. The Lord Bishop of London [Feb. 5,

of our oldest cathedrals. The crowd was so great that it had to be
addressed from various platforms, of which he occupied one. He
told me that he was led by his architectural surroundings to indulge
in a peroration in which he exhorted his hearers to act worthily of
their mighty past, and pointed to the splendid building as a perpetual
memorial of the great deeds and noble aspirations of their forefathers.
The allusion fell upon dull ears ; no cheer was raised ; the point was
entirely missed. My friend then strolled to the next platform, where
a longer- winded orator was indulging in a lengthier speech. He, too,
selected the cathedral to give local colour to his peroration. He
denounced the wrongs of the people, and shook his fist at the great
church as the symbol of oppression, the home of purse-proud prelates
who adorned themselves and their belongings at the expense of the
poor. But in this case also no cheer followed ; again a rhetorical
sally which owed its point to any feeling for the past was unheeded.
The working men cared neither for the good nor the evil of the past ;
their minds were set upon the present, and that was enough for them.
I think this indifference would not be shown nowadays. One view or
the other would raise a hearty cheer. There is nowadays a concep-
tion that things have grown, and that the way to mend them is to
get them to grow in the ri^ijht direction. This attitude of mind is
the abiding contribution which a knowledge of history will make to
social progress. Perhaps every branch of knowledge is more valu-
able for the temper which it creates, which can be shared by every one,
than by its direct contributions, which can be judged by only a
few. Again, I say, let us welcome the results of knowledge in any
and every form.

It is not, however, my intention to-night to criticise the various
ways in which history has been written. It is enough to say that it
is not absolutely necessary to be dull in order to prove that you are
wise, or to repress all human emotion in order to show that you are
strictly impartial. On the other hand, the perpetual appeal to
sentiment grows tedious, and the steadfast desire to construct a
consistent character by disregarding uncomfortable facts, or explain-
ing them away, does not carry conviction. It is even more impossible
to write history with a purpose than it is to write fiction with a purpose.
Fiction can at least select its own limitations, and professedly excludes
all the events of the lives of its characters except what suits its imme-
diate purpose. We know that the state of the world's affairs could not
be set to suit a particular past, and that men cannot be read into the
expression of abstract principles. History is very impatient of direct
morals. Its teaching is to be found in large tendencies, which, it may
be, are very imperfectly traceable within particular limits. History
cannot be made picturesque by the skill of the writer. It must be
picturesque in itself if it is to be so at all. All that the writer can
claim is the artistic insight which discerns the elements of a forcible
composition in unexpected places, and reveals unknown beauties by
compelling attention to what might otherwise be overlooked.

1897.] on the Picturesque in History. 315

We may agree that history should be made as picturesque as
possible ; but picturesqueness cannot be applied in patches. Char-
acters must be made life-like by remembering that after all they were
human beings, neither wholly good nor wholly bad, but animated by
motives analogous to those which animate ourselves, and are common
to man in all ages. An historian ought to live with his characters
as much as possible, and form a conception of their temperament and
appearance, so as to feel that he is dealing, not with dummies, but
with real persons. This is not always the method pursued. I re-
member being told by a friend that he was in a great library, and
saw a popular writer anxiously searching the catalogue, with a bundle
of proofs under his arm. He proffered his assistance, as he was
merely reading at large for a few days, and would be glad to have an
object. " Oh," said the author with a sigh, " I want to know the colour
of So-and-so's hair, and I don't know where to find out." My friend
spent three days in discovering this fact, and observed, when the
book appeared, that the information was used in a description of the
hero at a great crisis of his fortunes : " He stood with his shock of
red hair and flashing eyes," &c. Now in this case it is obvious that
the judgment on which the book was written was formed first, and
then picturesque details were sought to deck it out. I have some-
times meditated whether or no the judgment would have been the
same if the writer had known at first that his hero had red hair. As
we are affected in daily life by personal appearance as an index of
character, so we might well be affected by some corresponding con-
ception of temperament in great men of the past. Historical portraits
are very valuable ; the knowledge how a man's appearance impressed
those who saw him is equally valuable. No outburst of description
makes a man real. This is only possible by a sympathy between the
writer and his character, which penetrates all that he says of him.
A large, yet consistent, representation is the best form of picturesque-
ness in this important field.

The danger of an excessive desire for picturesqueness is that it
leads to a purely external view of the course of affairs. The writer
passes hastily from one strongly marked personality to another, from
one striking event to another, and neglects all that lies between them.
Yet personalities are only really interesting as they exhibit tendencies
which are widely spread ; and it is the strength of these tendencies
which finds expression in the dominating character. In fact, the
character itself is of no value for the purposes of history unless it be
brought into relation with the general conditions of life and thought
which produced it. This is the difference between history and fiction.
For the purposes of fiction you have to grant the possibility of the
character which is analysed or displayed in action. For the purposes
of history you have to understand the correspondency of the char-
acter with the conditions and circumstances of national life. It requires
a skilful delineation of those conditions to give a character historical
reality. He cannot be detached from his background. His whole

316 Tlie Bight Bev. The Lord Bisliop of London [Feb. 5,

interest lies in the fact that he really existed, and he must above all
things be made possible. The reader must not be left bewildered
and amazed, asking himself what sort of men lived on the earth in
those days, and what were the interests and pursuits of the ordinary
man.

It is obvious, therefore, that all history cannot be made equally
picturesque, and that it is useless to attempt to make it so by de-
liberate omissions of all that is not picturesque. We must take
human affairs as they come. After all, men did not live in the past for
our amusement, but for our instruction. There were probably as
many dull people in the past as there are in the present, and we
may console ourselves with that reflection. I can see no reason why
any one should read history except that he wishes to learn how things
really went on. I do not know that any method of writing can make
them always exciting. I hear people sometimes complain, " The
newspapers are very dull to-day." I find they mean that there is
no record of a great accident, or a horrible murder, or a political
catastrophe. I think, however, they would change their remark and
become very serious if, let us suppose, the newspapers chronicled
a great railway accident on every day in one week. They would
crave for a period of uneventfulness, and think that it was more
permanently satisfying. We need a stable basis to rest upon before
we can find comfortable i)leasure in contemplating instability.
Picturesqueness must have an element of restfulness. It is not
to be found in constant excitement, but in clear-cut and attractive
presentation of events.

The possibility of such presentation, strange to say, becomes
greater as the events are more remote. This is due to two causes :
first, that we have made up our minds more clearly about what is
imjjortant in the past ; secondly, because the amount of materials
which are available is limited. There is an immense difference
between writing history previous to the sixteenth century and
writing history after that date, owing to the nature of the material.
The change which separates modern from mediaeval times was made
by the conscious growth of nations, and the consequent complexity
of international relations. The difficulty of dealing with modern
history is the imjwssibility of isolating events and their results.
This truth is expressed in the amazing development of diplomacy
and the vast multiplication of documents, which is to the historical
craftsman the dividing line between two periods. The contemporary
chronicler, who was previously the chief authority, sinks into the
background. The historian has to wander patiently through end-
less byways, which lead apparently nowhere. It is comparatively
easy to form a clear conception of a man's character when you have
only the general outlines of his life and the record of his permanent
achievements. It is much more difficult when you can follow his
projects from day to day. The great mass of those projects came to
nothing. Yet it is true, if we look to private life, that a man's

1897.] on the Picturesque in History. 317

character is more revealed by what he tries to do than by what he
succeeds in doing. Indeed, it is not paradoxical to say that his
abiding influence is expressed by his aspirations rather than by his
achievements. His most fruitful heritage is, generally speaking,
his temper, his attitude towards life, his method of facing its
problems. The great question is, Did he heighten or did he lower
the sense of duty of those amongst whom he lived and worked?
The same mode of judgment seems to me to hold true in the large
aifairs with which history is concerned. Before we can judge a
statesman rightly we must follow his aims and methods in detail.
He could only command certain forces, the power of which was best
known to himself. It is easy to prescribe an heroic policy at
great crises, to lament apparent pusillanimity, and to arrange
quietly in one's study, after a lapse of centuries, an ideal termination
to political difiiculties. But we are all of us conscious of the
difference between what we would do and what we can do. Every-
body who sits on a committee comes away feeling that he could
have managed its business better by himself. But the use even of
a committee is to show you what available resources a particular
line of action can command; and you generally depart with a
conviction that it is ODly the second-best policy which has any
chance of immediate success. Statesmen in the past suffered under
the same limitations. The possession of supreme power by rulers
is only apparent. Somehow or other they had to discover what
the nation was likely to do, and more than that they could not
venture to undertake. Improvements in the mechanism of govern-
ment are of use as they enable statesmen to gauge more accurately
the forces on which they can rely. There is one lesson that comes
from reading diplomatic records: it is that rulers were always
trying to make the best of a bad business. Parliamentary obstruc-
tion is only a condensed form of what had always to be reckoned
with. The outward expression of tendencies has changed, rather than
the tendencies themselves.

It is very difficult to clothe with any appearance of interest
abortive attempts which came to nothing, which were put forward
in ambiguous language, and were often cloaks to some further
purpose behind. Yet, as a matter of fact, these constituted the
main activity of many statesmen, and if we leave them untraced or
unmentioned, we are missing the point of their laborious lives.
There is no more widespread delusion than that a man in a great
position gets his own way. He is envied by the ignorant and
thoughtless for his supposed power, for his freedom from those petty
inconveniences of which they themselves are keenly conscious.
The opportunity to do what one wills — this is assumed to be the
privilege of those who direct affairs. One of the great lessons of
history is to show the bondage, as well as the responsibility, of
power. The trials and disappointments of the great deserve recogni-
tion— not only their failures in great undertakings, the dramatic

318 The Bight Bev. The Lord Bishop of London [Feb. 5,

downfall of over-lofty schemes, but the small difficulties of their
daily business, the imperious limitations by which they were con-
stantly hampered. This has a meaning of direct importance to us
all ; but it is hard to make the troubles of daily life picturesque.
The writer of fiction moves us by the stirring adventures of his hero
and heroine in overcoming difficulties which stood in the way of
their marriage. Then he leaves them to settle down to humdrum
life as best they can. They are no longer interesting, but become as
ignoble and commonplace as their parents were at the beginning of
the book. The historian cannot treat his personages in the same
way. He has to face the difficulty of extracting some interest from
their average occupations. He is tempted to shirk it, and to hurry
on to something in which he can find fuller scope for his power of
description.

It is, therefore, this diplomatic record which goes far to injure the
picturesqiieness of history. It constantly reveals limitations which
could not be overcome. It shows us the hero in his shirt-sleeves,
labouring mostly in vain, and it enables us to see only too clearly
his inevitable defects. But if we look a little longer we see that it
enlarges his personality, and exhibits him as the representative of
his nation. This really sets him on a higher level, and gives him a
greater dignity. He is bearing the burden of his country, and is
fettered by her deficiencies. There are many things which might be
done if he had the means to do them. He can only reckon on so
much, and must make it go as far as he can. His projects are
tentative, and he is often obliged to withdraw from much for want
of a little. He is not really his own master, but serves a public
which imperfectly understands its own position and grudges every-
thing it gives. Whatever else picturesqueness may attempt to do, it
must not seek to abolish the pathos of humble industry.

I have been speaking generally about picturesque ways of writing
history, in the ordinary acceptation of the term. Let me attempt to
go a little farther, and try to discover in what the picturesqueness of
history consists. It is obvious that, if it lies in a series of vivid
pictures of events and striking presentations of character, the historian
cannot rival the writer of fiction, and historical novels are the proper
mode of expressing picturesque presentation. Some historians have
felt the need of a more imaginative treatment than their subject
properly allowed, and have supplemented their serious histories by
historical novels. But the point which I wish to consider is the
sense in which history can be made picturesque, and the reason why
some periods of history are more capable of picturesque treatment
than others.

Now the term picturesque itself suggests artistic handling ; and it
is obvious that in art as much depends on the selection of the
subject as on the mode of treating it. An historian is bound by his
subject, and cannot make it picturesque if it is not so in reality. The
great periods of picturesqueness are those in which personality is

1897.] on the Picturesque in History. 319

most powerful. This constitutes to many minds the charm of the
history of Italy, especially in the fifteenth century. There was then
a copious supply of determined and adventurous characters, whose
main object was to express themselves fully. Outward circumstances
gave them a favourable opportunity. They rose by their own
dexterity, and aimed at artistic completeness in all their achieve-
ments. They are attractive by their freedom from conventional
restraints, by their unhesitating self-confidence, and by the magnifi-
cence of their aims. The same spirit which animated Italy passed
on in a somewhat modified form to the rest of Europe in the sixteenth
century, and became domesticated in France. From that time
onward we may say that French history is the most picturesque.

Yet it is worth observing that a mere expression of character,
unfettered by ordinary restraints, does not of itself satisfy our craving
for picturesqueness. In fact, the most purely personal history is that
of the later Koman Empire, of the Byzantine Empire, and of its
successor, the Russian Empire. For striking scenes and dramatic
events, these histories surpass any others. Caligula and Nero, Leo
the Isaurian and Irene, Ivan the Terrible and Peter the Great,
outstrip in wilfulness and daring anything that Italy or France ever
produced. Yet they seem to us remote and monstrous ; they do not
touch us with any sympathy ; they belong to a range of ideas which
is not our own ; they represent characteristics of power with which we
are not familiar. It is not enough that scenes should be striking, or
characters strongly marked. Scenes and characters alike must stand
in some definite relation to ourselves and our actual surroundings.
I doubt if our interest in Italian history would be so strong were it
not for the fact that its records still remain and have their message
for us. Italian princes would be forgotten had they not been patrons
of artists and architects, whose works speak to us by their beauty and
their grandeur. We wish to know what was the view of life which
gave these creations such dignity and grace, who were the men for
whom such stately palaces were built, what was the conception of
human character and its possibilities which prevailed in the com-
munity from which they sprang? The men themselves are only
interesting because they were conspicuous and intelligible instances
of tendencies which we wish to see expressed in action, that we
may more clearly understand their meaning as expressed in the
abstract forms of architecture and art. Our interest is not primarily
in the men themselves, or their doings, but in the significance of the
ideas which lay behind them. The same thing is true of the
picturesqueness of French history. We are attracted by the process
which produced that mental alertness and precision which characterise
the French mind, that power of organising life so as to get the most
out of it, which is still the peculiar merit of the French people.

This leads me to another point. A bald record of events or a
faint description of a character by a contemporary does not suffice
for historical picturesqueness. Things may loom large, and we may

320 The Bight Bev. The Lord Bishop of London [Feb. 5,

see their importance, but we cannot hope to reproduce them by mere
exercise of imagination. Picturesqueness must come from adequate
materials, and every touch must be real. Imagination, after all, is
only an arrangement of experience. You cannot really create ; you
are only borrowing and adjusting odds and ends according to some
dominant conception. It is useless in history to read a man about
whom little is known into the likeness of another about whom you
may know much. It is useless to reproduce an obscure period in
the terms of a period with which you are more familiar. Where we
do not know we cannot safely invent. Now picturesqueness in
history must depend on the material available for intimate knowledge.
It is only at times when men were keenly interested in life and
character that such records were produced. We cannot make the
life of Byzantium live again, for the records are formal and official.
Outside accounts of magnificence suggest little ; we need the touch
of intimacy to give life. In short, picturesqueness is only possible in
dealing with periods when literature was vigorous and contemporary
memoirs were plentiful.

I should not like to say whether the demand created the supply,
or the supply created the demand. It is enough that men were
interested in themselves and in one another, and have left us the
result of their interest. That interest arose from a belief in the
importance of what was happening, and a power of tracing it to
individual action. Hence prominent individuals were closely
scanned, their motives were analysed, and the influences which
weighed with them were carefully observed. In some cases the men
themselves were worthy of study : in other cases their importance
was entirely due to their position. But anyhow they were represen-
tatives of their times, of the habits, manners and ideas which were
current. The picture which we wish to have in our own minds is
not merely that of the man, or of the events in which he took part,
but of the life and the society which lay behind him.

The picturesqueness of history, therefore, is largely due to
memoirs ; and the countries and epochs which have produced them
are especially picturesque. Now it is great crises, periods of
disruption, great emergencies, which as a rule impress contemporaries
and furnish matter for close observation. The production of crises
is, of course, not the highest sign of human intelligence. In fact,
a crisis is due to blundering and incapacity. But when a crisis
occurs it is a revelation of character. This is obvious in the drama.
It is impossible to represent an ordinary man engaged in his ordinary
pursuits. To show what sort of man he is, it is necessary to place
him in an extraordinary and unexpected position; then all his
hidden strength or weakness comes to light. A man can only be
defined by his limitations ; and these are only obvious when he has
to act on his own initiative, robbed of his ordinary props, and forced
to draw upon his own intellectual and moral resources. Hence it
comes that we feel the attraction of troublous times in history, and

1897.] on the Picturesque in History. 321

regard them as the most picturesque. The Great Rebellion and the
French Eevolution have furnished endless motives to dramatists,
novelists and painters, because they suggest possibilities of striking
contrasts, and afford available situations. The human interest is
then most intense, and our sympathies are most easily awakened.

But though such times are the best for displaying individual
character, it may be doubted if they are the best for displaying
national life and national character. Indeed, they exaggerate differ-
ing tendencies which, in an ordinary way, work harmoniously
together, and force them into violent opposition. It is true that the
tendencies were there, that they rested upon certain ideas and made
for certain ends. But in the exigencies of a struggle they assumed
undue proportions and became one-sided through the apparent
necessity of denying any right of existence to the ideas opposed to
them. In short, national life depends on the blending of various
elements, and the co-operation on a large scale of efforts which,
regarded on a small scale, seem to be diametrically opposed. Periods
of revolution destroy this process, and make the apparent opposition
an absolute one for a time, so that the parallel between the individual
and the nation fails in this point. A crisis in the life of the
individual reveals his true character, because it compels him to
gather together the various elements of which that character is com-
posed and condense them into a decisive act. In the case of a nation
the contrary occurs. The crisis dissolves the bands which bind
national character together, and sets some of its elements against
others. All are equally necessary ; they must ultimately be recom-
bined and reabsorbed ; they do not really exist in the form in which
they show themselves under the exigencies of conflict. Revolutionary
epochs may be the most interesting, but they are not the most instruc-
tive. They may show us forcible characters, but these characters are
rarely attractive. They may emphasise natiooal characteristics, but
they do not show them in the form in which they really work. It
is true that a decisive choice will be made which elements are to be
dominant in the new combination. So far as those elements were
unknown and unsuspected before, the interest lies in discovering their
origin and the source whence they drew their power. The picturesque-
ness of revolutionary periods is really dramatic and psychological,
not strictly historical.

We come back, therefore, to the position that history is pic-
turesque at those epochs when national tendencies are expressed in
individual characters, and when the consciousness of this fact creates
a literary study of those characters which is given in considerable
detail. It is worth while to go a step further, and consider what may
be learned from this fact. Perhaps this may best be done by
reference to the history of our own country, with which we are most
familiar.

English history is not very picturesque. It has not produced a
large number of striking situations or of strongly marked characters.

322 The Bight Bev. The Lord Bishop of London [Feb. 5,

It is by no means rich in memoirs, and the most stirring times have
not called forth the most vivid description of their incidents. There
is no brilliant biography of Oliver Cromwell, for instance, by a con-
temporary. We have to piece together materials for the characters
of Henry VIII., Elizabeth, Mary Queen of Scots, and Charles I. No
one at the time attempted to grasp them. The dramatic moments of
their careers were only dimly and imperfectly felt. Let me illustrate
what I meant when I said that it was impossible for later writers to
create deeper impressions than were present in the minds of con-
temporaries. Two situations occur to me as surpassing all others in
English history in vividness and dramatic effect ; they are the murder
of St. Thomas of Canterbury and the death of Wolsey. This is
entirely due to the fact that they profoundly moved men's minds at
the time, and are recorded in language which is full of the emotion
so engendered. Both were regarded as great and significant cata-
strophes, important in themselves and in their results. The death of
Wolsey is a remarkable instance. In outward circumstance it is
inferior to the execution of More or the burning of Cranmer. Yet
it remains more picturesque. We feel that More and Cranmer fell
in a way like soldiers on the field of battle. They shared the
fortunes of their cause, and our interest lies in discovering the exact
point on which they took their intellectual stand, and laid down their
lives rather than take a step further. But Wolsey is a type of human
fortunes, of the inherent limitations of man's endeavours, of the sudden
reversal of high hopes, of the restless chafing of an imprisoned spirit,
and its final despair. This position arises from the literary skill of
his biographer, Cavendish, reflecting doubtless the permanent im-
pression of his time, and expressing with deepening melancholy the
profound pathos of the wreckage of a life. This intensity of feeling
could not have gathered round an ordinary career, but was engendered
by the profound conviction that with the fall of Wolsey England had
entered upon a new course in its national life — a course the end and
goal of which no man could foresee. Wolsey had striven to make
England powerful in a changing world. He had created forces which
he could not restrain within the limits which his prudence had pre-
scribed. There was deeper emotion at the downfall of him who
strove to keep the peace than over the sad fate of combatants on either
side when once war had been proclaimed. It is only the pen of one
who is conscious of living through such a crisis that can be instinct
with real feeling and can convey that feeling to after-times.

It is curious to observe that these two instances of Thomas of
Canterbury and Wolsey, are both cases of men who pursued clear
and decided objects, and whose characters consequently detached
themselves from the general background of contemporary life. The
objects which they pursued were not in either case popular, and
they had to trust mainly to their own resoluteness and skill for
ultimate success. Hence came the attraction of their characters for
their biographers. They were men who could bo studied and de-

1897.] on the Picturesque in History. 323

scribed in themselves, apart from the results of their actions. In
fact, any estimate of or sympathy with their line of action was entirely
secondary to the interest of the men themselves. In this sense they
resemble the subjects of Italian or French history. They rose to
power by their own capacity, and they used their position consciously
lor the furtherance of objects which they deliberately selected for
themselves. It is this which gives a picturesque interest to
characters in history. We are most easily attracted by a sense of
completeness and self-determination. This, indeed, is the artistic
quality in character, and alone admits of clear and forcible delineation.
Opportunism, however successful, cannot well be depicted clearly ; it
must be considered by reference to a number of possibilities, and
challenges our judgment at every step. A man who is doing his best
under untold difficulties may be heroic, but he rarely enjoys any
great moments which set forth his heroism in a striking way. Our
judgment may after a long survey recognise his w^orth, but that does
not make him picturesque. William the Silent can never fill a large
canvas, great as was his contribution to the best interests of the
world.

The picturesqueness, then, of the history of any nation, or period,
depends upon the possibility of an individual detaching himself from
ordinary life in such a way as to express in himself its unconscious
tendencies. The possibility of such individual detachment depends
on the ideas on which the ordinary life of the nation is founded. If
these ideas are to be represented by a person, they must be compara-
tively simple. For this reason great crises in a nation's history are
the most picturesque, for they simplify national ideas by forcing one
or two great principles into temporary supremacy over all else. Yet
even in great crises England has not brought forth clearly repre-
sentative characters. Oliver Cromwell, for instance, was the executor,
rather than the representative, of the principles of the Great Eebel-
lion. They were never definite enough to be summed up by any
individual. However highly we may rate Cromwell's capacity,
we cannot make him out as eminently picturesque, or place him by
the side of Napoleon.

We may, 1 think, go a step further. The ideas on which national
life are founded may be ultimately reduced to the national conception
of liberty. Ultimately each man values the society of which he
forms part for the opportunities which it affords him of doing or
being what he wishes to do or be.

Now there is a difference, which is not always recognised, in the
meaning of liberty to different peoples. It would be a long matter
to attempt to explain this difference in detail and account for it. But
we may say generally that it depends on the way in which the rights
of the individual are regarded in relation to the rights of tlie com-
munity. Let me apply this to the instances of picturesqueness which
I have taken. In Italy, in the sixteenth century, the communities
were so small, and their position was so precarious, that men longed

324 The Bight Bev. The Lord Bishop of London [Fob. 5,

for the growth of a national spirit, as the limits in which their actual
life was lived were too narrow to express that life in its fulness. A
nation could only be formed by the power and influence of a
dominant and resolute personality. Hence men were so interested
in the development of such a personality that they were ready to
watch various experiments and to endure much tyranny in the hopes
of final success. This created a curious accentuation of the value of
individual character, and an absence of any sense of its limitations,
which was undoubtedly fitted to produce picturesqueness, but had
serious drawbacks in practice.

In the same way, the historical circumstances of the consolidation
of the provinces of France under the Monarchy developed a high ap-
preciation of individual character ; and the keenly logical intelligence
of the French mind gave it a permanent place in literature.

England, on the other hand, became in early times an organised
community, and there was no violent break in the pursuit of this or-
ganisation. I cannot now trace in detail the results of the different
course of English and French history as reflected in the characters of
the people. But this at least is obvious : the average Frenchman
conceives of himself as having a right to gratify his individual desires,
without thought of others, to a degree unknown to the average
Englishman. French civilisation is concerned with the arrangement
of the externals of life in the most comfortable way. English civili-
sation is concerned primarily with political institutions and with
the organisation of the activities of life. The Frenchman conceives
himself as an individual, the Englishman conceives himself as part
of a community. The Frenchman, though wedded to his own country,
and having no desire to leave it, still considers himself as a citizen
of the world. The Englishman, though a rambler and an adventurer,
ready to make his home anywhere, still considers himself an English-
man wherever he goes. France took for the motto of its aspirations
" Liberty, Fraternity, Equality." I believe that if England* had had
occasion to formulate its aspirations in the same way, its motto would
have run " Liberty, Justice, Duty."

Now picturesqueness is obtained by isolating men from their
surroundings, by getting clear-cut situations. To this a Frenchman
lends himself ; he is accustomed to think and act by and for himself. An
Englishman objects to isolation ; however much he may be alone, and
however decidedly he may act, it is as a representative of England,
with a mass of national tradition behind him, which he would not
rid himself of if he could. He will take enormous responsibility
upon himself, but while taking it repudiates it. He minimises his
own individual part in what he does, and is persistently apologetic.

1 think I can illustrate my meaning from our literature. Shake-
speare has shown with curious insight the difference between northern
and southern peoples. Othello and Romeo, when touched with passion,
are pure individuals, and act entirely with reference to their own
feelings. The difficulties of Hamlet lay in the fact that he could not

1(S97.] on the Picturesque in History. 325

forgot that lie was heir to the throne of Denmark, and could not act
in such a way that righteous vengeance should seem to be private
ambition. He could not escape from his attachment to society, and
therefore he will always fail to have the picturesqueness which
belongs to individual detachment.

I have been speaking of picturesqueness in its ordinary sens6.
The upshot of my remarks is that in proportion as history is pic-
turesque in this sense it is not really history. For history is con-
cerned with the life of the community, and picturesqueness with the
character of individuals. But there is, I think, a larger and truer
picturesqueness, which may be found not in details but in principles.
The great object of liistory is to trace the continuity of national life,
and to discover and estimate the ideas on which that life is founded.
Individuals are only valuable as they express those ideas and embody
that life. Such expressions are often to be found in lowly places, and
are manifested in inconspicuous lives. It is the true function of
history to discover and exhibit them wherever they may be. In our
own history, at all events, I am convinced that we need a heightened
sense of the causes which produced those qualities which have created
the British Empire. The most picturesque hero is the English people
itself, growing through manifold training into the full manhood which
it still enjoys. What made it ? What principles does it embody ?
How may these principles be enlarged in view of its great and growing
responsibilities ? These are questions which have an undying
interest, and men's minds are being more and more turned towards
them. For us, at all events, the highest imaginative charm gathers,
not round individuals, but round the growth of our conceptions of
public duty. To trace the growth of that body of ideas wliich make
up England's contribution to the world's progress, to estimate their
defects, and to consider how they may be increased by broader
sympathies and greater teachableness — this is a task which requires
the (jualities at once of a scientific explorer and of a consummate
aitist.

Vol. XV. (No. 91.)

326 Professor John Milne [Feb. 12,

WEEKLY EVENING MEETING,
Friday, February 12, 1897.

George Matthet. Esq. F.E.S. F.C.S. Vice-President, in tlie Chair.

Professor John Milne, F.R.S. F.G.S.

Becent Advances in Seismology.

As an introduction to the discourse for this evening, I feel it my
duty to call attention to the broad meaning which it now seems
necessary to apply to the word Seismology. Only a few years ago
the occupation of the seismologist was strictly confined to the study
of sudden movements which from time to time take place in the
crust of our earth. These movements, although sometimes violent,
were to him transient phenomena which seldom continued longer
than a few seconds, or at the most one or two minutes. Recent
investigations have shown that the same disturbances are preceded
by minute tremors which, under certain conditions, may last many
minutes, whilst after all movement to which we are sensible has
ceased, the ground may palpitate for many hours. Another set of
phenomena to which attention is now directed, are the earthquakes
which are repeated many times per year in every country in the
world, which by our unaided senses are passed by unnoticed. In
short, the unfelt evidences of seismicity are much more general than
those which are accompanied by destruction and alarm, and a new
seismology has been discovered which is at least as important as
the old.

Now that we are assured that the greater number of earthquakes
are but intermittent accelerations in the more general movements of
rock folding and rock crushing, to separate the announcements that
these mighty changes are in operation from the changes themselves,
is to separate an infant from its parent, an effect from its cause.
Besides these legitimate relations of earthquakes, the practical
seismologist finds that he often records movements of a quasi-seismic
origin, together with others like diurnal waves, and tremors which
find an explanation in causes external to the surface of our earth.
These latter are at present without a home, and although they are
non-seismic, in many instances at least, they represent actual move-
ment in the ground, and seismology finds itself in the position of
foster-mother to strange children. These various movements which
take place within and on the surface of the earth, the study of which
may, until we find a more suitable word, be embraced under the term
seismology, are indicated in the following table : —

1897.] on Becent Advances in Seismology. 327

1. Bradyseismic or slow secular changes, resulting in tlie elevation
or depression of countries and mountain ranges.

2. Secular flow or crush. Of this we have only indirect evidence.

3. Annual or longer period changes in level.

4. Earthquakes or accelerations in bradyseismic action or secular
flow. Volcanic earthquakes. Sea waves. Air waves.

5. Unfelt earthquakes, common to all countries.

6. Irregular changes in level completed in a few minutes, or in
many days.

7. Diurnal waves.

8. Tremors, or microseisms and pulsations. Possibly in part
atmospheric movements.

The advances that have been made during recent years by
recording movements which may possibly have a bradyseismical
character are, as compared with the information derived from the
study of the other movements with which we have to deal, but few
in number. Both in Germany and in Japan, horizontal pendulums
have been carefully installed underground, and it has been found
that in both instances, as with the levels of Plantamour, although
there is an annual change in inclination which cannot be accounted
for by seasonal changes in temperature, there is for periods of several
years' duration a continuous tilting in one direction.

A very curious observation made in Tokio, was, that very often
for several days before a local earthquake, a horizontal pendulum
would gradually wander towards the west. Although such a sequence
in phenomena may have been accidental, because it has been shown
by observation with seismographs founded on the solid rock that the
greatest and most frequent motion is in the direction of the
dip rather than parallel to the strike, indicating that the direction of
folding is a direction of pronounced yielding, whilst slow change in
level is apparently most pronounced in districts where mountain
growth is possibly yet in progress, we see in the Japan observations
an indication of the possibility that crises in bradyseismical motion
may be foretold.

I learn from Col. J. Farquharson, H.E., Director of the Ordnance
Survey, that some years ago the question whether during recent years
there had been any changes in level in Britain was carefully tested
in Lancashire and Yorkshire, under the direction of Sir Charles
Wilson. The first levelling in these counties was carried out between
1843 and 1850, and the second between 1888 and 1894. Excepting
in the coal and salt districts, no material changes were found to have
taken place. It is, however, to be remembered that this re-levelling
was confined to lines of level along roads, and whether there have or
have not been any changes in the height of hills or mountains since
the first measurements were made we do not at present know.

One method of measuring bradyseismical eftects within a period
of three or four years, and to determine how far such movements may
be connected with the occurrence of earthquakes, would be to estab-

z 2

328 Professor John Milne [Feb. 12,

lish in a suitable district a triangular arrangement of three sets of
levels, the distance between each set being several miles. All the
instruments should be on the rock, and displacements parallel and at
right angles to the dip should be recorded.

A summary of all the advances which have of late years been
made in the study of earthquakes would, in great measure, be found in
an epitome of the twenty volumes which since 1880 have been published
by the Seismological Society of Japan, a work which is being
actively continued by a committee supported by the Japanese
Government.

Previous to 1878 our knowledge of the charActer of earthquake
motion was largely dependent upon the effects snch motion produced
upon various bodies and upon our senses. To correct and extend
this knowledge, students of earthquakes in Japan at about this time
devoted nearly their whole attention to seismometry, first testing pre-
existing forms of apparatus, and then experimenting with forms
which were new. Those instruments which were intended to record
the rapid and violent movements of the ground, whether these were
in a vertical or horizontal direction, did this relatively to a mass so
suspended that, although its suj)ports v/ere moved, a point in this
mass remained practically at rest. An account of these seismograj^hs
was in 1888 given to this Institution by Prof. J. A. Ewing, F.R.8.

For earthquakes in which there was a vertical component of motion,
however, it was soon noticed tliat these " steady points " were swung
from side to side by tilting, and instruments had then to be devised
to measure angular displacements. Following these came a class of
instruments intended to record the slow undulatory and often unfelt
earthquake motions. These, together with a group of tromometers or
tremor measurers — apparatus to record the time at which shocks had
occurred — resulted in the development of a group of instruments
which would require for their description a volume on Seismometry,
and it is fair to say that the seismometry of Japan revolutionised the
seismometry of the world.

After the new inventions, the story of which forms one of the
most important in Japanese seismology, records were obtained which
showed that the impressions we had with regard to earthquake move-
ments had been widely incorrect, whilst they also indicated that our
estimates in mechanical units of seismic destructivity had been
founded on a wrong hypothesis. Having given the dimensions of a
body that has been overturned, or the dimensions and tensile strength
of a wall or column-like structure that has been shattered, we are
now in a position to calculate the acceleration to which the same has
been subjected, and the result arrived at is not far removed from
calculations of the same quantity derived from the diagrams obtained
at the same time and at the same place from a seismograph. Inves-
tigations of this description have been applied with marked success to
construction, and as new engineering works and new buildings spring
up in Japan, we see that rules and formulae are followed which are

1897.] on Becent Advances in Seismology. 329

unknown and not required in countries free from earthquakes. That
these rules, which take into consideration that structures have to
withstand stresses due to more or less horizontal displacements at
their foundations, have been followed, is in itself a testimony that
engineers regard them as being worthy of consideration, and we now
feel assured that when an earthquake like that of 1891, which cost
Japan 10,000 lives and an expenditure on repairs of at least
30,000,000 dollars, is repeated, the losses will be comparatively
trifling. That the new departures in engineering and building
practice have proved beneficial has been repeatedly demonstrated.
Because experiments showed that earthquake motion at a compara-
tively shallow depth was somewhat less than what it was upon the
surface, a number of modern and important buildings in Tokio have
had given to them deep foundations and are surrounded by open areas.
On several occasions these buildings have stood unimpaired whilst
neighbouring structures have been badly shattered.

The tall chimneys of factories, as well as those of ordinary
dwellings, have been so far modified that the new forms stand whilst
the old forms fall. The greatest material benefits which seismology
has conferred upon Jaj^an will, however, probably be found in the
radical changes which are taking place in the construction of ordinary
dwellings.

One application of seismometry to the working of railways in
Japan has resulted in a saving of fuel of from 1 lb. to 5 lbs. of coal
per mile per locomotive. In these and other ways, by following up
initiatives created during the last twenty years, Japan has reached
a high position, if not foremost, amongst nations who have given
attention to seismology. The Government of that empire, recog-
nising the value of what has been already accomplished, and that
much more is yet oj^en to investigation, have at their university
established a Chair of Seismology, a committee which is liberally
supported, to make investigations relating to earthquakes an,d their
effects, and a seismic survey of their empire.

When we remember that a single earthquake has often cost Japan
a far greater loss of life and an expenditure of jDublic funds at least
comparable with that accompanying her recent war, it is not remark-
able that her chief interest in earthquakes has been directed towards
means to mitigate their effects; by doing which, whilst conferring
benefit on herself, she has also conferred benefits upon the earthquake-
shaken countries of the world. Notwithstanding this, questions of
interest to science have not been overlooked. The object of one series
of experiments, which were carried out at intervals extending over
several years, was to measure the velocity with which disturbances pro-
duced by explosions of dynamite and other substances were propagated,
and to study the character of the vibrations as they radiated from
their source. Near to an origin a clear separation between normal and
transverse movements was observable, which at distances exceeding
50 or 100 feet was lost. Single waves as they spread outwards wero

330 Professor John Milne [Feb. 12,

seen to gradually change into double waves. The velocity of propa-
gation evidently increased with the intensity of the initial impulse ;
it was greater for vertical and normal than for transverse waves, and
vibrations generally were propagated more rapidly to stations near
an origin than between stations at some distance from the same.
These and many other results were confirmed and extended by
records obtained from a series of nine seisraometric stations situated
on a plot of ground the area of which was only a few acres. In these
investigations the records, which were drawn upon the surfaces of
smoked plates, were those of real earthquakes. The motion on one
side of this ground was invariably so much greater than it was
900 feet distant upon the other side, that it offered an explanation
for the peculiar distribution of ruin so often observed in a city after
it has been shaken by an earthquake. The houses in one street
may stand, whilst others possibly not more than 100 feet distant, also
standing on alluvium, but somewhat softer in character, may be
shattered. From the survey of a field, seismic investigations were
extended to the survey of Tokio, and then to the survey of the
northern half of Japan. At this point the Government came to
the assistance of private observers, and took under its control the
survey of the whole empire, embracing an area of 140,000 square
miles, within which there are now close on 1000 stations at which
earthquakes are recorded.

The results of this undertaking are not at present fully known.
"What we have learned is that during the last six years the average
number of shocks have been about three per day, a frequency which
is greater than that which is usually given for the whole world.

If we take the well-marked earthquake districts of the world and
give to them frequencies one-third of that in Japan, it would not be
an over-estimate to say that 10,000 movements sufficiently strong to
be felt and shake considerable areas of our planet occur every year.
Five thousand of these come from the home of our deep-sea cables.

The Japan earthquakes, like those of South America, mostly
originate on the side of the country which slopes steeply down beneath
the Pacific Ocean. In fact, it may be taken as a rule that whenever
ground over a considerable distance, which I will take at 120 geogra-
phical miles, has an average slope greater than 1 in 50, in such
districts under the influence of bradyseismical bending or of secular
crush round the base of the continental domes, earthquakes are
frequent. From Japan to beneath the Pacific, slopes of 1 in 25
occur, whilst on the coast of Peru slopes as great as 1 in 16 may
be found. The volcanic districts of Japan which, like those of South
America, are found along the upper part of a bradyseismic fold, are
singularly free from earthquakes, and the times of seismic and
volcanic activity show no marked connection.

The analyses of the Japan records, as a whole, as with the analysis
of the records of most other countries, show a marked annual and
semi-annual periodicity. The former of these, which shows a winter

1897.] on Recent Advances in Seismology. 331

maximum for both hemispheres, is attributed by Dr. C. G. Knott *
to the fact that in winter we have large accumulations of snow and
steeper barometric gradients than in suiumer, and it is these inequa-
lities of stress of long continuance which cause yieldings to be more
frequent at one season rather than at another.

The most important feature in the Japanese records, which gives
to them a value greater than those of any other country, is the fact
that the various shocks may be classified according to the district
from which they originated, and at the same time a value or
weight can be given to each, according to the area it disturbed, whilst
primary and secondary shocks can be readily separated from each
other.

The advantage of such tables, when, for example, we seek for a
possible connection between certain lunar influences or the rising of
the tide upon a coast, because such influences are at a maximum in
different districts at different hours, is at once apparent, whilst all
surprise that investigators who have only had at their disposal tables
of earthquakes the origins of which have been in widely separated
districts have failed in establishing laws, which we might anticipate,
at once disappears.

Thanks to the liberality and foresight of the Japanese Govern-
ment, we are now in a position to make investigations hitherto
impossible, and to confirm or disprove very many of the results of
previous investigators. Dr. Knott, who is engaged upon these volu-
minous statistics, finds a confirmation of the law of Perry that there
is a maximum in earthquake frequency near the time of perigee ;
that there are maxima associated with the moon's declination ; its con-
junction with the sun ; the time of the moon's meridian passage ;
and the ebb and flow of tides. Until these investigations have been
completed and published, their importance cannot be fairly estimated.
Dr. F. Omori has pointed out the existence of diurnal and semi-
diurnal periodicities, and that the frequency of after-shocks follows
fairly definite laws ; the former of which investigations has by rigid
treatment been emphasised and extended by Dr. C. Davison.

Many investigations have been made to discover a relationship
between seismic phenomena and those of an electric or magnetic
character, but the only certain result is to show that the artificial or
actual shaking of the ground near to an earth plate may be accom-
panied by temporary currents, whilst the displacement of large bodies
of strata, as for example those which accompanied or caused the earth-
quake of 1891, may result, as pointed out by Prof. Tanakadate, in a
permanent readjustment in the relative position of the isomagnetics
in a district.

After this earthquake, the cause of which was attributable to the
sudden fracturing of rocks, the line of v/hich is traceable on the

* Trans. Seis. Soc. vol. iv. pt. 1, " Earthquake Frequency," C. G. Knott,
F.R.S.E.

332 Professor John Milne [Feb. 12,

surface over a distance of 40 miles, many opportunitieis presented
themselves for the observation of sound waves. Often a subterranean
boom was heard, unaccompanied by any sensible shaking, but more
frequently it was a warning that within a very few seconds there would
be a more or less violent shaking.

If we assume that the sounds originated at the same foci as the
after-shocks, the velocity with which the former were transmitted was
therefore higher than that at which the latter were transmitted. But
inasmuch as observation showed that the earth waves had a velocity
seven times as great as an air wave, the conclusion is that whatever
may be the mechanical action producing the earthquake sound, it is a
vibratory motion transmitted tl^roifgh the rocks ; and because it is never
audible at many miles distant from its source, the vibrations producing
it either raj)idly die out or change in character.

Another interesting investigation, which is by no means completed,
has been to note the effects produced by earthquakes upon the lower
animals, several of which are apparently more alive to the existence
of minute tremors than human beings. The effect produced by earth-
quakes on human beings, which partakes largely of an emotional and
moral character, is a subject about which many interesting facts have
been collected.

Perhaps the greatest triumph in seismological investigations is
the fact that \ye are now assured that if a large earthquake occurs in
any one portion of our globe, it can with suitable instruments be
recorded in any other portion of the same. Because the rate at which
these movements are propagated is so very high, in some instances
approaching 12 km. per second, or double the rate at which a wave of
pompression could pass through steel or glass ; because at a given
station we have never recorded two disturbances which we should
expect had the movement like a barometrical wave been transmitted
in all directions round the earth ; and finally, because it appears that
the velocity to points at a great distance from an origin is higher than
that to points relatively near to the same, the conclusion for the
present is that the motion, rather than being propagated round our
world, is propagated through the same.

Inasmuch as thpse velocities throw light upon the effective rigidity
of the materials constituting the paths along which they were de-
termined, the importance of establishing, say at twenty existing
observatories willing to co-oj)erate, instruments to record these earth
movements is at once apparent. The cost of such a set of instruments,
required to carry out a seismic survey of the world, would be about
1000^.

At the observatories where these instruments were established, in
addition to the speedy announcements of great catastrophes in distant
places, the records of these, and of disturbances of a more local origin,
would throw light upon some of the otherwise unaccountable de-
flections sometimes fc>hQ\vn in phqtograms from magnetographs, baro-
graphs and other instruments sensible to slight displacements ;

1897.] on Recent Advances in Seismology. 333

whilst, as will be shown later, changes in level, affecting astro-
nomical observations, would be continuously recorded.

From the times at which movements were recorded at different
stations, it would seem possible to localise the origins of disturb-
ances which in many instances are submarine. This would throw new
light upon changes taking place in ocean beds, lead to the identifica-
tion of districts which those who lay cables are desirous of avoiding,
and sometimes enable us to attribute cable ruptures to natural rather
than to artificial causes.

Another function of instruments which record these unfelt move-
ments is that their records may often be used to anticipate, confirm
or to correct telegrajDhic information, which are matters of great im-
portance to all communities. Good examples of work having this
character are seen if we compare the records obtained in the Isle of
Wight and the telegraphic information respecting the three disasters
which last year were sooner or later after their occurrence reported
as having taken place in Japan.

For some weeks our newspapers told us that on June 17th the
eastern coast of Japan had been inundated by sea waves, and that
something like 30,000 people had lost their lives. Those who had
reason to believe that either on the 16th or 17th, vessels, whether
men-of-war or merchantmen, or even friends travelling on land,
were to reach the stricken districts on these dates, probably felt some
anxiety respecting their safety. The Isle of Wight seismograms
showed that in this instance there had been an error connected with
telegraphic transmission, of two days, the disaster having taken place
on the 15th, whilst on the 16th and 17th all was quiet.

On August 31st similar diagrams indicated that at a distance of
about 6000 miles, and therefore probably in Japan, there had been a
very violent disturbance commencing at 5.7 p.m. For detailed in-
formation about this catastrophe we had to wait until mails arrived
some four weeks later. These earth messages reached England from
Japan in 16 minutes.

The last disaster, which was reported as having taken place in
Kobe, created considerable anxiety with many who had friends and
property in that prosperous little city. An absence of records in the
Isle of Wight indicated that there had at least been gross exaggera-
tion in the telegraphic news, whilst some weeks later it was discovered
that the widely published message, which had been sent regardless of
the alarm it might create, was devoid of all foundation.

These, then, are a few of the advantages we should expect from a
seismic survey of the world, and all that is required to carry the
same into effect is a sum which is very much less than that which is
required for the purchase of a modern telescope.

From these disturbances, the origins of which are to be found in
gradual or sudden yieldings within the crust of our globe, I will now
pass to those movements the origin of which is apparently traceable
to external influences, the most interesting of which is the diurnal

334 Professor John Milne [Feb. 12,

wave. At Shide, in the Isle of Wight, where instruments like conical
pendulums are installed with their booms in the meridian on the
eastern side of a valley which runs north and south, the movements
are such that on fine days these booms point towards the sun, indicat-
ing that in the morning there is a downward tilting towards the east,
and in the afternoon towards the west ; at night the motion is east-
wards. The direction of this movement, which may have a range of
2" or 3", is, however, at the same time different at different places ; for
example, in Japan, on parallel ridges bounding a swampy valley, the
simultaneous movements on these ridges were found to be in contrary
directions ; that is to say, they were such that we may imagine the
trees on the opposite sides of the valley every day to ha ve performed
a slow bow to each other.

Because these movements are practically confined to fine weather,
whilst in dull wet weather they are hardly discernible, we should
imagine them to be the result of expansions and contractions in the
surface soil, or warping of the piers carrying the instrument follow-
ing changes in temperature ; but when we find that they are practically
as marked in an underground chamber, where the changes in tempera-
ture are exceedingly small, the suggested explanation apparently fails.

Another cause to which we may turn, as possibly throwing light
upon these movements, lies in the fact that, by the action of the sun,
there is on two sides of most observing stations a difference in the
load which, by evaporation, is carried up into the atmosphere
and there dissipated. As an illustration of this, if on one side
of an observatory we had a field of clover and on the other side
a surface of earth, the difference in the loads removed during a
day in summer would often exceed 12 lbs. per square yard. Be-
cause the clover side would be the one which would be the most
relieved, this would tend to rise, and the pendulum would swing
towards the uncovered surface. At night-time the causes leading
to a slow return of the pendulum towards its normal position would
be varied. For example, the area which during the day had lost the
most by evaporation would be the one presenting the greater number
of points for the condensation of moisture as it rose from the ground,
which, on the bare side, would be free to escape to the atmosphere ;
hence the clover-covered surface would, relatively to the ground on
the opposite side of the pendulum, grow heavy, be depressed, and the
pendulum take up a retrograde motion, which usually appears to be
somewhat less than the daylight displacement.

Another phenomenon bearing upon the movement during the
night is the almost unstudied sub-surface precipitation of moisture.
Experiment has shown that in certain cases after sunset, when the
surface of bare earth is chilled or, in winter, frozen, aqueous vapour
rising upwards beneath such an area, instead of escaping to the atmo-
sphere is condensed underground, and the superficial soil grows
heavier. Soil which is tilled with stones probably shows this in
a marked manner ; each stone, being a good radiator, is at night

1897.] on Recent Advances in Seismology. 335

quickly chilled to form a condenser, beneath which moisture collects
which otherwise wo aid have escaped to the atmosphere. For this
reason fields containing a certain number of stones are more fertile
than others where stones are absent.

Another important question, bearing upon differential loading of
differently covered areas, depends upon the existence or non-existence
of a covering of vegetation. We know how much many plants pump
upwards to transpire during the day, but their action during the
night is to the writer quite unknown. Daring the night this trans-
piration may be small, but are they yet pumping to replace their
daylight loss ?

An action of this sort, if it exists, only implies a transfer of load
from beneath to a higher level on the surface, but if on one part of
an area with a common water supply this goes on, whilst it does not
take place on another portion of the same, it would follow that the
former might be superficially altered in form. What is here stated
respecting the cause of the diurnal wave is only a suggestion waiting
disapproval or confirmation.

Changes of level are closely connected with rainfall, which, when
it saturates a valley has, at one station at least, been accompanied
by movements indicating an increased steepness of the bounding
hills. Daring fine weather the motion is reversed, or, in other words,
the surface movements on the two sides of a valley, with alternations
of fine or wet weather, have corresponded to a concertina-like opening
or shutting of the same. Certain seasonal changes in level may in
part be due to the removal and replacement of loads represented by
leaves and plants.

The last group of movements on which I shall touch are pulsations
and tremors, the existence of which are supposed to be indicated by
the regular or irregular swingings which are from time to time
established in pendulums and other forms of apparatus which are
delicately suspended. The occurrence of the latter movements,
which have been so carefully studied for many years in Italy, and
automatically recorded in Japan, show remarkable relationships to
the localities where they are observed, the instruments by which they
are recorded, to the seasons, the hours of the day and night, and to
a number of meteorological phenomena.

In Japan, tremors were never observed underground upon rock
foundations, which, however, has not been the case in Italy. At one
station they may be marked, whilst at another station, only a few
hundred yards distant, they may be only shown feebly or be entirely
absent. A light horizontal pendulum is usually more disturbed than
one that is relatively heavy. Tremor frequency and tremor intensity
are more frequent during the night than daring the day. A favourite
hour for tremors to appear, or to attain a maximum, is about 6 a.m.,
and at one station they were always to be seen between midnight and
this hour. They are much more frequent during winter than during
summer, when barometric changes are rapid, and when the observing

336 Prof. John Milne on Becent Advances in Seismology. [Feb. 12,

station is crossed by a steej) barometric gradient, whether the local
barometer is high or low. Tremors may be marked during a calm,
whilst during a gale, when doors and windows rattle, a tromometer
may be at rest. They are frequently observed during a frost or thaw,
and they are generally frequent when the temperature is falling and
when it is low. Although waves beating on a coast may produce
fretillements upon a surface of mercury, such actions are apparently
unconnected with the swinging movements of tromometers.

Because tremors are seldom observed in a very dry building or in
an instrument beneath a well-ventilated covering, I am inclined to
the opinion that many of these perplexing disturbances can be ex-
plained on the assumption that, from time to time, beneath cases
which are even air-tight a circulation of air is established. This is
brought about, as may be shown experimentally, either in consequence
of a difference in temperature in different parts of a case, or, as is
shown by the introduction of a desiccating agent like calcium
chloride, by the difference in the rate at which moisture is condensed,
absorbed or given off at different points within such a cover.

Although a suggestion like this tends to destroy many of the
records of so-called earth tremors, and for years daily maps were
issued showing the microseismic activity of the Italian peninsula, we
are left confronted with phenomena which it is the interest of all who
work with instruments susceptible to these influences to understand
more clearly

Most particularly we should like to know the reason of their
frequency at particular hours and seasons, but above all things, how
to avoid visitors which may accelerate or retard the swinging of a
pendulum, or cause inaccuracy in the weighings of the assayer.

[J. M.]

1897,] ApproacJiing Itetnrn of ihe November Bleteorp, 337

WEEKLY EVENING MEETING,
Friday, February 19, 1897.

8tr Frederick Abel, Bart. K.C.B. DXIL. LL.D. F.R.S,

Vice-President, in the Chair,

G. Johnstone Stoney, Esq. M.A. D,Sc. F.R.S. 3I.B.L

The Approaching Beturn of the Great Swarm of November Meteors.

The present discourse was intended to supplement one delivered
eighteen years before, in the Theatre of the Royal Institution, oil
* The Story of the November Meteors,' of which a copious extract
will be found in vol. ix, of the Proceedings of the Institution.

Orbit of the Leonids.

In the earlier discoui'se an account was given of the successive
steps which led up to the great discovery by the late Professor J.
Couch Adams of the orbit of these meteors. They novr pursue, and
have been for several hundreds of years pursuing^ a long oval path in
the heavens, round which they travel three times in each century.
This orbit near its distant end intersects the orbit of Uranus and
very close to its perihelion it intersects the orbit of the earth. It
does not intersect the orbits of the intermediate planets, of which
the principal are Jupiter and Saturn, since the plane in which the
meteors move is so much inclined to the planes of the orbits of those
planets that the meteors are carried above and below their orbits in
each revolution. The swarm is extended like an immense procession
many millions of miles in length, though only some 100,000 miles
wide, along a portion of its orbit. During one half of each revo-
lution the stream is for sixteen years lengthening out as it approaches
the sun, and during the other half of the revolution,' while receding
from the sun, it shortens again, not, however, quite to the same size
as it had at the commencement of the revolution, since one revolution
after another there is a gradual increase in the length of the pro-
cession.

Entrance of the Leonids into the Solar System^

After the lapse of a sufficient time the swarm will of necessity
have so lengthened out as to extend the whole way round its orbit •
and the consideration that it is at present of limited lent^th, viewed
in connection with the dynamical certainty that it must ever keep
steadily extending, carries our thoughts bask to that past time, which
cannot be very remote from the cosmical standpoint, when that
which is now a long stream was a compact cluster. It was then,

338 Mr. G. Johnstone Stoney [Feb. 19,

whenever that epoch was, that these meteors entered the solar
system ; and in the former lecture the reasons were given which led
the late Professor Le Verrier to fix upon the spring of the year
A.D. 126 as the date of this remarkable event, when the swarm,
which had up to that time been an independent cluster, became
a member of the solar system. The cluster at that time seems
to have been travelling inwards from open space towards the sun,
past which it would, if unimpeded, have made a single sweep,
and would then have receded from the sun's neighbourhood to the
same immensity of distance from which it came. But while advan-
cing towards the sun, the great planet Uranus seems to have crossed
its path. The cluster of meteors must have nearly collided with
that great planet ; in fact, passed so close that the planet was able
to drag the group quite out of its previous path, after which the
planet advanced along its own orbit, and left the individual meteors
to pursue whatever orbits round the sua corresponded to the speed
and direction of motion which the planet had impressed upon each of
them. Previous to their encounter with the planet the great meteoric
cluster seems to have had sufficient coherence from mutual attraction
to be able to maintain itself as a compact group. But in sweej)ing
past so great a planet the difference of force acting on the members
of the group would probably be too great for their feeble attraction
towards one another. They got a little scattered, and when aban-
doned by the planet, found themselves too far asunder to admit of
their assembling again into a compact body ; a? id since then each
meteor has had to pursue independently its own orbit round the sun.
These orbits, though very close to one another, are not quite the
same ; they differ a little in every respect, and amongst the rest, in
their periodic times. The average period of traversing the orbit is
nearly 33} years. For some of the meteors it seems to be a week
longer, and for others a week shorter than their mean period.
Hence, at the end of their first revolution, the meteors with the
shortest periodic time came to their starting point a fortnight sooner
than the greatest laggards. At the end of two revolutions they were
a mouth asunder, and so on until now, at the end of 63 revolutions,
the foremost of the procession comes round two jears in advance of
the hindermost.

Astronomers already know much which seems to support this re-
markable hypothesis of Le Verrier's ; but it is most desirable that
probability shall be changed into certainty one way or the other ; and
the lecturer urged that a great effort ought to be made on the occasion
of the approaching return of the great swarm, to secure observations,
so full and so accurate as will enable either ourselves or our posterity
to trace back with precision the history of the Leonids in the past,
and so ascertain with certainty whether it was, or was not, within a
few days of the end of February in the year a.d. 126, that these
innumerable minute bodies began their present career within the
solar system.

1897.] on the ApproacMug Beturn of the November Meteors. 339

When the Meteors will return.

The immense procession takes two years to pass the point where
it pours across the earth's orbit. This point the earth reaches every
year about the middls of November, and accordingly, when the
meteors return the earth will certainly, in two successive years, pass
through the stream, and may also encounter the front or rear of the
procession in a third year. In this way we may count on having
great meteoric displays on whatever is the advancing side of our
earth in each of two successive years, in November 1899, and in
November 1900, with perhaps a third display in either 1898 or 1901.
In the middle of November of the year 1898 the moon will be absent,
and if by good fortune the head of the meteoric stream shall have
arrived so soon, which, however, is doubtful, we may expect an immense
display then on one half of the earth. In 1899, when it appears
certain that the stream will be encountered, there will unfortunately
be moonlight, which will detract from the splendour of the display,
though it need not take away our prospect of securing invaluable
photographic records in that year, since it has been found that such
photographs may be taken even in strong moonlight.

Sporadic Leonids.

Another matter to which attention was invited was that of the few
scattered Leonids which the earth meets with every year, and not
only in the years of the great displays. Their presence may be
accounted for as follows.

The meteoric stream is about 100,000 miles across — more than a
third of the way from the earth to the moon — and through it the
earth passes obliquely, occupying about five hours in the transit.
The earth intercepts some of the meteors, which plunging with
immense speed into our atmosphere, are first heated by the friction to
brilliant incandescence, and then dissipated in vapour before they
can get within miles of the earth's solid surface. This produces
the splendid spectacle which we are privileged to witness on such
occasions. But many as are the meteors which the earth intercepts,
those are immensely more numerous which pass close enough beside
it to be bent by its attraction a little out of their previous orbit —
only a little, however, on account of the enormous speed with which
they shoot past the earth, a speed of about 45 miles a second — so that
each is not so much as three minutes in darting past the earth.
The earth has plunged some sixty or seventy times through the
stream, and has thus diverted from their natural course a vast number
of the meteors. But however great this number may be, the number
of those which were too far off to feel any influence from the earth is
immeasurably greater. In fact, the meteoric stream is about as long
as from Jupiter to the earth, so that the earth when it passes through
the stream can affect but a very short piece of its whole length.

Those Leonids that have been thus affected are they that have

340 Mr. G. Johnstone Stoney [Feb. 19,

since become sporadic Leonids. They traverse new ortits a little
differing from the great meteoric orbit, and also differing from one
another. By a well-known dynamical law, they would, if subsequently
acted on only by the sun's attraction, return accurately at the end of
each revolution to the situation close to the earth's path which they
occupied when the earth, after having dragged them a little aside,
passed on along its own orbit. Since the sun's attraction upon them
is immensely more powerful than any other, they, on the completion
of every revolution, return nearly to that situation, which the earth
passes each year in the middle of November ; but since their motion^
are slightly perturbed, especially by the great planets Juj)iter and
Saturn, tbey get to| be somewhat scattered into situations behind and
in front of that point in the earth's orbit, as well as, no doubt, many
of them sideways, so that a few of them may encounter, though many
more of them must escape, the earth. This scattering of the sporadic
Leonids is what causes the earth to meet with a few of them for
some days before and after it reaches the point of intersection of its
orbit with that of the main swarm.

Again, when the earth diverts a meteor from its path, it slightly
alters every element of its orbit. Among others, it alters its periodic
time. Hence in each subsequent revolution the meteor which has
been disturbed will either draw ahead of the main swarm or fall
behind it ; and this has caused the sporadic meteors to be now dis-
tributed round the whole length of the orbit, so that the earth
encounters some of them every year, and not only at intervals of
33 years.

Such is a sufficient picture of what happens in the case of ordi-
nary sporadic Leonids. But there is one among them which is go
peculiar that it deserves separate treatment.

Of TempeVs Comet.

Astronomers know very little of the dynamics of comets, very-
little of the dynamics of clusters of stars, and almost nothing of the
dynamics of nebulae. When any one of these problems shall be
solved, it will probably throw much light on the other two. Mean-
while, whatever may be the dynamical relation in which the tail of a
comet stands to its nucleus and to the other bodies of the solar
system, we know at all events that its nucleus travels along an orbit
Under the same laws as an ordinary mass of ponderable matter. Now
the orbit of the nucleus of Tempel's comet is nearly but not quite
coincident with that of the main swarm of November meteors, a^
appears from the following table of the best determinations we yet
have of the elements of both orbits.

Leonids. Tempel's Comet.

Period .. .. .. 33-25 .. 33-18 yenrs-

Mean distance 10-3402 .. lC-3248

Excentricity 0-9047 .. 0-9054

Perihelion distance .. .. .. ., 0-9855 .. 0*9765

Inclination .. 16° 46' .. 17° 18'

Longitude of node 51° 28' .. 51° 26'

Distance of perihelion from node .. 6^51' .. 9 2'

1897.] on the Approaching Return of the November Meteors. 341

It will be observed that each of the elements of the orbit of
Tempel's comet diifers, but only differs a little, from the correspond-
ing element of the orbit of the meteors. Differences of this kind have
established themselves in the case of every one of the sporadic
meteors which have got separated from the main swarm by the earth.
And this gives rise to the suspicion, almost amounting to belief,
that the comet was at one time a member of the swarm, and was
drawn a little aside on one of the occasions when the earth passed
through the stream. Since that event Jupiter and Saturn have
been incessantly perturbing its orbit and that of the meteors a little
differently, and have thus increased the divergence. Now, if we can
determine the orbit of the comet with great accuracy, it will become
possible to ascertain with precision what these perturbations have
been in the last few centuries, and thus to trace back the path which
the comet has pursued in space. If this can be done satisfactorily,
we shall be able to find when it was that the comet was so close to
the earth that the earth was able to alter its whole future history.
This is another problem which the lecturer invited astronomers to
set before them, and in order to prepare for it, to make the most
exact observations that are practicable upon the comet on the occasion
of its approaching return.

The Main Swarm.

We may next turn to the main swarm. The inclination of the
orbit of the meteors to the planes in which Jupiter and Saturn travel
has been referred to above. The meteors, on account of this inclined
position of their orbit, glide at a distance of many millions of miles
over and under the orbits of those planets, and the planets, as they
pass through the inclined orbit of the meteors, are favourably situated
for modifying that orbit by their attraction. One of the principal
effects that they thus occasion is to make the meteoric orbit, instead
of standing out from the sun in one fixed direction, to shift slowly
round in the same direction in which the planets travel round the
sun. This shifting of the orbit of the meteors has caused the time
when the earth encounters the swarm to have gradually advanced
from October 12th (Old Style), when the earth encountered the swarm
in A.D. 902 (this being the first visit of the meteors of which we
possess a record) until November 13th (New Style), when the great
shower of 1866 was discharged upon the earth. The point on the
earth's orbit where the meteors' orbit intersects is called the node of
the meteors' orbit. Accordingly, the facts are usually described by
saying that the node of the meteoric orbit has shifted forwards along
the earth's orbit from the place which the earth reaches each Octo-
ber 19th, which is equivalent in the new style to the date which was
called October 12th in a.d. 902, until November 13th or 14tb, which
is the present date. Thus the shift forwards in a thousand years of
the date on which the showers occur has been about three weeks and a
half, and we know that a similar shift must have been going on before

Vol. XV. (No. 91.) 2 a

342 Mr. G. Johnstone Stoney [Feb. 19,

that time. A diagram illustrating these facts will be found in vol. ix.
of the Proceedings of the Royal Institution, opposite to page 43.

It was by a study of this advance of the node, and by referring it
to its dynamical cause, that Professor Adams was able to discriminate
between five different orbits which had been found by Professor
Hubert Newton to be compatible with all other known facts. This
enabled hiin, in April 1867, to announce which was the real orbit.

Professor Adams, in his computations, used a method of investi-
gation known as Gauss's method, in which what he really computed
was the perturbing effect on a meteor of two rings of attracting
matter with the form, size and position of Jupiter's and Saturn's orbits,
the masses of the rings being equal to the masses of the planets, and
being distributed round the ring not equally, but with a preponderance
where the planet, in travelling along its orbit, lingers longest. Now
the actual amount by which the node shifts between successive returns
of the meteors differs slightly from revolution to revolution ; because
the amount in any one revolution depends on what have been the
distances and directions of the planets from the meteors during that
particular revolution. But what Gauss's method does is to give the
average amount of this shift taking one revolution with another, and
this will in some revolutions be a little more, and in others a little
less, than the actual amount. The difference between the actual and
the average amount is well exemplified by the annexed diagram of
the times at which the great showers have been observed, and the
times at which they would have occurred if the advance of the node
had not deviated from its average amount.

In the left-hand part of the diagram the longitudes of the node
along the earth's orbit corresponding to the observed dates of the
showers are plotted down. These show an irregular advance of the
node towards the right-hand side of the figure. The straight line
indicates where the node would have been if its advance had been
uniform ; and in the right-hand part of the figure are given the
number of hours by which the actual shower preceded or followed the
time when it would have occurred on the uniform hypothesis.

Now there is nothing except the want of more accurate data than
we yet possess to prevent the calculation being carried farther than it
was by Professor Adams, and made to furnish the actual amount of the
Bhift in each individual revolution ; indicating not qnly that, but the
small difi'erence which must exist between the perturbations upon the
front, the middle and the back of the stream, so as to enable us
to determine the sinuosities which must have established themselves
in it.

There is a circumstance to which it may be useful to invite
attention in connection with the calculation of the perturbations of
the Leonids. The planets that are massive enough and so situated
as to be able to atfect the meteoric orbit are Jupiter, Saturn and
Uranus, and in every one of these cases there is a remarkably simple
jiumerical relation between the periodic time of the Leonids and that

1897.] on the Apiwoaching Ueturn of the Nomnher Meteors. 84o

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344 Mr. G, Johnstone Stoney . [Feb. 19,

of the planet perturbing tbeir motions. The most conspicuous of
these relations is that 14 revolutions of Jupiter in his orbit occupy
almost exactly the same time as five revolutions of the Leonids —
probably exactly the same time as five revolutions of those meteors
which occupy the foremost position in the procession. This re-
markable cycle has, therefore, been repeated as many as ten times
since the year a.d. 126, when it is supposed that the meteors entered
the solar system. Similar relations exist between the periodic time
of the Leonids and those of the planets Saturn and Uranus. Now
students of what is known as the " Planetary Theory " are aware
that numerical relations of this kind produce a very marked effect
on the perturbations, tending to make the perturbations in a short
limited time conspicuously different from their mean values, and ren-
dering it all the more necessary in the interests of physical astronomy
that such observations shall be made and such data collected when
the great stream returns to us, as will enable the computations to be
made for each revolution separately.

At present we can only predict the return of a shower from our
knowledge of the average amount of the shift of the node, and the
time so determined is, as we see from the diagram, usually several
hours before or after the actual time. If we could calculate the per-
turbations in a single revolution we should be in a position to compute
the actual time. Even making use of the elements of the orbit as
already determined by Professor Adams from imperfect data, it V70uld
probably be possible to make a moderate approximation to the amount
of the perturbations between 1866 and 1899, so as to be able to come
nearer to ascertaining the hour at which the next meteoric shower
will commence than we can at present. It is to be hoped that this
eminently useful computation will be made before November 1898,
since it is possible that the head of the swarm will have reached the
earth's orbit by that time.

But still more important information may emerge if we can
calculate with sufficient accuracy the perturbations in individual
revolutions. It will become possible to explore the past, to trace
back the history not only of the meteoric procession as a whole, but
of each part of it, and so ascertain with certainty when and through
what instrumentality it was that these foreigners annexed themselves
to the solar system. Similar information may be won in reference to
Tempel's comet. We may discover when and on what occasion this
body broke away from the main stream. These, if they can be
effected, will be great achievements, and will show the observers and
mathematicians of the present generation to be worthy successors of
the great men — Professors Adams, Hubert Newton, Le Verrier and
Schiaparelli — who made careful preparation before the return of the
meteors in 1866, so that the most instructive observations might then
be attempted, or who afterwards made use of the materials so collected
to splendid effect

1897.] on the Approaching Beturn of the November Meteors, 345

The Observations now most wanted.

The immediate lessons we seem to learn from the whole survey are,
that while observations upon sporadic Leonids are of little import-
ance, the utmost eflforts should be made to determine with more
accuracy than has hitherto been possible the radiant point of each of
the different parts of the main stream through which the earth will
pass in 1899 and 1900, and perhaps in 1898. Every method, both
by direct observation and by photography, should be carefully
planned beforehand, and employed when the critical opportunity
comes. It is of special importance that the observations shall be
divided into sections, each extending over a short time — say not more
than a quarter of an hour — and that a careful record be kept of the
times of the several sections of observations, in order that it may be
possible afterwards for the mathematician to compute and allow for
the amount of deflection effected by the earth's attraction upon the
meteors observed in each of these sections of time. This is a very
necessary improvement ujDon the methods used in 1866. It is indeed
essential where our aim is to attain great accuracy. Now very
much greater accuracy in the observations than that which was at-
tained in 1866 is imperatively required for the dynamical calculations
which it is desirable that our mathematicians should be enabled to
grapple with.

The matters, then, that are most immediately pressing are : —

1. To make preparation with the utmost forethought for the
observations on the main stream, especially for the determinations of
the radiant point in each quarter of an hour.

2. To make the fullest and most careful observations that are
possible upon Tempel's comet. Some of these may probably be by
photography.

3. To compute, so far as can be accomplished with our present
materials, the perturbations which the planets Jupiter, Saturn and
Uranus have effected on the orbit of the Leonids between November
1866 and the present time.

[G. J. S.]

310 . Lknt.-Colond C. B. Cornier [Feb. 20,

WEEKLY EVENING MEETING,
Friday, February 26, 1897.

Basil Woodd Smith, Esq. F.R.A.S. F.S.A. Vice-President,

in the Chair.

Lieut.-Colonel C. R. Conder, R.E. D.C.L. LL.D. M.K.A.S.
Palestine Exploration.

The object of exploration is to obtain accurate knowledge of a country,
its inhabitants, and its extant monuments and texts. That of
Palestine has special interest to Christian races and to Jews, as serving
to explain more clearly the sacred literature of their Faith.

The results of such exploration may be judged by looking back a
century to the time of Bayle, Voltaire and Astruc, when what was
regarded as advanced scientific work assumed that the Hebrews were
a savage race without literature, that history only began to be written
about 500 B.C., and that the oldest civilisation was that of China and
India. It is now known that the art of writing was practised in
Egypt and Chaldea as early as 3000 B.C., that the Canaanites about
the time of Joshua had a civilisation equal to that of surrounding
nations, as had also the Hebrew kings ; while, on the other hand,
Chinese civilisation is only traceable to about 800 B.C., and that of
India was derived from the later Persians, Arabs and Greeks. These
results are due solely to exploration.

The requirements for exploration demand a knowledge not only
of Syrian antiquities but of those of neighbouring nations. It is
necessary to understand the scripts and languages in use, and to study
the original records as well as the art and architecture of various ages
and countries. Much of our information is derived from Egyptian
and Assyrian records of conquest, as well as from the monuments of
Palestine itself. As regards scripts, the earliest alphabetic texts
date only from about 900 B.C., but previous to this period we have to
deal with the cuneiform, the Egyptian, the Hittite and the Cypriote
characters. The explorer must know the history of the cuneiform
from 2700 b.c. down to the Greek and Roman age, and the changes
which occurred in the forms of some 550 characters originally hiero-
glyphics, but finally reduced to a rude alphabet by the Persians, and
iised not only in Babylonia and Assyria but also as early as 1500 b.c.
in Asia Minor, Syria, Armenia, Palestine, and even by special soribes
id Egypt. He should also be able to read the various EgyjDtian

1897.] on Palestine Exploration. 347

scripts — the 400 hieroglyphics of the monuments, the hieratic, or
running hand of the papyri, and the later demotic. The Hittite
characters are quite distinct and number at least 130 characters,
used in Syria and Asia Minor from 15 0 B.C., or earlier, down to
about 700 B.C. The study of these characters is in its infancy. The
syllabary of Cyprus was a character derived from these Hittite hiero-
glyphics, and used by the Greeks about 300 B.C. It includes some fifty
characters, and was probably the original system whence the Phoenician
alphabet was derived. As regards alphabets, the explorer must study
the early i'hoenician, and the Hebrew, Samaritan and Moabite, with
the later Aramean branch of this alphabet, whence square Hebrew is
derived. He must also know the Ionian alphabet, whence Greek and
Eoman characters arose, and the early Arab scripts — Palmyrene,
Nabathean and Sabean, whence are derived the Syriac, Cufic, Arabic
and Himyaritic alphabets.

As regards languages, the scholars of the last century had to deal
only with Hebrew, Aramaic, Syriac, Coptic and Greek, but as the
result of exploration we now deal with the Ancient Egyptian whence
Coptic is derived, and with various languages in cuneiform script,
including the Akkadian (resembling pure Turkish) and the allied
dialects of Susa, Media, Armenia and of the Hittites ; the Assyrian,
the earliest and most elaborate of Semitic languages; and Aryan
tongues, such as the Persian, the Vannic and the Lycian.

The art and architecture of Western Asia also furnishes much
information as to religious ideas, customs, dress and history,
including inscribed seals and amulets, early coins and gems. The
explorer must also study the remains of Greek, Eoman, Arab and
Crusader periods, in order to distinguish these from the earlier remains
of the Canaanites, Phoenicians, Hebrews, Egyptians and Assyrians,
as well as the art of the Jews and Gnostics about the Christian era,
and the later pagan structures down to the fourth century a.d.

The monuments actually found in Palestine are few though
important. The discovery at Tell el Amarna of about 150 letters
written by Phcenicians, Philistines and Amorites — and in one case
by a Hittite Prince — to the kings of Egypt, proves, however, the use of
cuneiform on clay tablets by the Syrians as early as 1500 B.C., and
one such letter has been recovered in the ruins of Lachish. The
oldest monuments referring to Syria and Palestine are found at
Tell LoTi, on the Lower Euphrates, and date from 2700 B.C. Next to
these are the Karnah lists of Tbothmes III. about 1600 B.C., record-
ing the names of 119 towns in Palestine conquered after the defeat
of the Hittites at Megiddo. These lists show that the town names
which occur in the Bible are mainly Canaanite and were not of
Hebrew origin. The Canaanite language of this period was practi-
cally the same as the Assyrian, excepting that of the Hittites, which
was akin to the Akkadian. In the next century the Tell el Amarna
tablets show that the Canaanites had walled cities, temples, chariots,
and a fully developed native art. They record the defeat of the

348 Lieut.-Colonel C. B. Cornier [Feb. 26,

Egyptians in the north by Hittites and Amorites, and tlie invasion
of the south by the Abiri, in whom Drs. Zimmern and Winckler
recognise the Hebrews, the period coinciding with the Old
Testament date for Joshua's conquest.

An inscription of Mineptah, discovered in 1893, speaks of the
Israelites as already inhabiting Palestine about 1300 e.g., and agrees
with the preceding. Other Egyptian records refer to the conquests
of Eameses II. in Galilee and in Syria, when the Hittites retained
their independence ; and in the time of Eehoboam, Shishak has left
a list of his conquests of 133 towns in Palestine, including the
names of many towns noticed in the Bible.

The Hittite texts found at Hamath, Carchemish and Merash, as
well as in Asia Minor, belonged to temples, and accompany sculp-
tures of religious origin. They are still imperfectly understood, but
the character of the languages, the Mongol origin of the people, and
the equality of their civilisation to that of their neighbours, have
been established, while their history is recovered from Egyptian and
Assyrian notices. The Amorites were a Semitic people akin to the
Assyrians, and their language and civilisation are known trom their
own records, while they are represented at Karnak with Semitic
features.

The oldest alphabetic text is that of the Moabite stone about
900 B.C. found at Dibon, east of the Dead ,Sea, on a pillar of basalt,
and recording the victories of King Mesha over the Hebrews, as
mentioned in the Bible. Several Bible towns are noticed, with the
name of King Omri, and the language, though approaching Hebrew
very closely, gives us a Moabite dialect akin to the Syrian, which is
preserved in texts at Samalla, in the extreme north of Syria, dating
from 800 e.g. The Phoenician inscriptions found at Jaffa, Acre,
Tyre, Sidon, Gebal and in Cyprus do not date earlier than 600 e.g.,
and show us a distinct dialect less like Hebrew than the Moabite.
The most important of these early texts is the Siloam incription in
the rock-cut aqueduct above the pool, found by a Jewish boy in 1880.
It refers only to the cutting of the aqueduct (in the time of
Hezekiah), but it gives us the alphabet of the Hebrews and a
language the same as that of Isaiah's contemporary writings. It is
the only true Hebrew record yet found on monuments, and confirms
the Old Testament account of Hezekiah's work.

The Assyrian records refer to the capture of Damascus by
Tiglath Pileser III. in 732 e.g., and of Samaria in 722 e.g., as well as
to Sennacherib's attack on Jerusalem in 702 e.g. The latter record
witnesses also the civilisation of the Hebrews under Hezekiah, whose
name occurs as well as those of Jehu, Azariah, Menahem, Ahaz,
Pekah and Hosea, who, with Manasseh, gave tribute to Assyrian
kings.

About the Christian era Greek texts occur in Palestine, the most
important being that of Herod's Temple at Jerusalem, forbidding
strangers to enter, and those of Siah in Bashan, where also Herod

1897.] on Palestine Exploration. 349

erected a temple to a pagan deity. Such texts are very numerous in
Decapolis, where a Greek j)opulation appears to have settled in the
time of Christ.

The geographical results of exploration are also important for
critical purposes. Out of about 500 towns in Palestine noticed in the
Old Testament, 400 retain their ancient names, and about 150 of these
were unknown before the survey of the country in 1872-82. The
result of these discoveries has been to show that the topography of
the Bible is accurate, and that the writers must have had an intimate
knowledge of the land. Among the most interesting Old Testament
sites may be mentioned Lachish, Debir, Megiddo, Mahanaim, Gezer
and Adullam as newly identified ; and of New Testament sites,
Bethabara, ^Enon and Sychar, all noticed in the fourth Gospel.

The existing Hebrew remains are few as compared with Roman,
Arab and Norman ruins of later ages. They include tombs, aque-
ducts and fortress walls, with seals, weights and coins. The most
important are the walls of the outer court of Herod's great temple at
Jerusalem, with his palace at Herodium, and buildings at Ceesarea and
Samaria. The curious semi-Greek palace of Hyrcanus at Tyrus in
Gilead dates from 176 B.C. In Upper Galilee and east of Jordan
there are many rude stone monuments — dolmens and standing stones
— probably of Canaanite origin, as are the small bronze and pottery
idols found in the ruins of Lachish. Sculptured bas-reliefs are, how-
ever, not found in Palestine proper, having been probably destroyed
by tbe Hebrews.

This slight sketch may suffice to show the advance in knowledge
due to exploration during the last thirty years. The result has been
a great change in educated opinion as to the antiquity of civilisation
among the Hebrews and Jews, and as to the historic reliability of the
Bible records. Further exploration, especially by excavation, may
be expected to produce yet more interesting results, and deserves
general support, as all classes of thinkers agree in the desirability of
increasing actual knowledge of the past. It is no longer possible to
regard the Hebrews as an ignorant and savage people, or to consider
their sacred writings as belonging necessarily to the later times of
subjection under the Persians. Internal criticism is checked and
controlled by the results of exploration, and by the recovery of
independent historical notices.

[C. K. C]

350 General Monthly Meeting. [March 1,

GENERAL MONTHLY MEETING.

Monday, March 1, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Frederick John Beaumont, Esq.

Major Charles Turner Blewitt, R.A.

John Fowler Leece Brunner, Esq.

James Cadett, Esq.

John Corrie Carter, Esq.

John Cohen, Esq.

Mrs. Thomas Collier,

John George Craggs, Esq.

Tbornycroft Donaldson, Esq. M.A.

Henry Edmunds, Esq.

Mrs. Henry Edmunds, »

Gilbert Strange Elliot, Esq.

William Adams Frost, Esq. F.R.C.S.

William Terrell Garnett, Esq. J.P.

Henry Andrade Harben, Esq.

Frederic Hewitt, M.D.

F. W. Hildyard, Esq.

Mrs. George King,

Henry Leituer, Esq.

Rev. James Dunne Parker, LL.D. D.O.L. F.R.A.S.

E. Mumford Preston, Esq.

John Morgan Richards, Esq.

Colonel George Sartorius,

Frederick Holland Schwann, Esq. B.A. LL.B.

William Robert Smith, M.D. D.Sc. F.R.S.E.

Henry Alfred Stern, Esq. M.A.

Charles John Stewart, Esq.

George Lawrence Stewart, Esq.

Mrs. Augustus D. Waller,

Mrs. J. Lawson Walton,

were elected Members of the Royal Institution.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. :—

FOR

Accademia dei Lincei, Reale, Boma — Classe di Scienze Fisiche, Matematiche e
Natural!. Atti, Serie Quinta : Rendiconti. 1° Semestre, Vol. VI. Fasc. 2.
Classe di ScieDze Morali, &c. Serie Quinta, Vol. V. Faec. 11, 12. 8vo.
1896-97-

1897.J ^ General Monthly Meeting. 351

American Academy of Arts and Sciences — Proceedings, New Series, Vol. XXIII.

8vo. 1896.
American Geographical Soriet//— Bulletin, Vol. XXVIII. No. 4. 8vo. 1896.
Astronomical Society, Royal — Monthlv Notices, Vol. LVII. No. 3. 8vo. 1897.
Boston Public Library—Monihlj Bulletin, Vol. II. No. 2. 8vo. 1897.
Boston Society of Natural History — Proceedings, Vol. XXVII. pp. 75-199. 8vo.

1896.
Botanic Society, Royal— Qimvterlj Record, Vol. VI. No. 67. 8vo. 1896.
British Architects, Royal Institute of — Journal, 3rd Series, Vol. IV. Nos. 7, 8.

4to. 1896.
British Asuociatinn — Eeport of Meeting at Liverpool, 1896. 8vo. 1896.

Toronto Meeting, 1897: Preliminary Programme. 8vo. 1896.
British Astronomical Association — Journal, Vol. VII. No. 4. 8vo. 1897.
Burton, S. James, Esq. F.G.S. (the Author) — The Westraliau Goldfields. 8vo.

1896.
Camhridrje Philosophical Society — Proceedings, Vol. IX. Part 4. 8vo. 1897.
Camera Club — Journal for Feb. 1897. 8vo.

Chemical Industry, Society o/— Journal, Vol. XVI. No. 1. 8vo. 1897.
Chemical Society — Journal tor Dec. 1896. 8vo.
Cracovie, Academic des Sciences — Bulletin, 1896, No. 10. 8vo.
Devonshire Association — Report and Transactions, Vol. XXVIII. 8vo. 1896.
Editors — American Journal of Science for Feb. 1897. 8vo.

Analyst for Feb. 1897. 8vo.

Anthony's Photographic Bulletin for Feb. 1897. 8vo.

Astrophysical Journal for Feb. 1897. 8vo.

Athenfeum for Feb. 1897. 4to.

Autlior for Feb. 1897. 8vo.

Bimetallist for Feb. 1897.

Brewers' Journal for Feb. 1897. 8vo.

Chemical News for Feb. 1897. 4to.

Chemist and Druggist for Feb. 1897. 8vo.

Education for Feb. 1897.

Electrical Engineer for Feb. 1897. fol.

Electrical Engineering for Feb. 1897. 8vo.

Electrical Review for Feb. 1897. 8vo.

Electricity for Feb. 1897. 8vo.

Engineer for Feb. 1897. fol.

Engineering for Feb. 1897. fol.

Homceopathic Review for Feb. 1897. Svo.

Horoloiiical Journal for Feb. 1897. 8vo.

Industries and Iron for Feb. 1897. fol.

Invention for Feb. 1897.

Journal of PJiysical Chemistry for Feb. 1897.

Law Journal for Feb. 1897. 8vo.

Life Boat Journal for Feb. 1897. Svo.

Lightning for Feb. 1897. 8vo.

Loudon Technical Edufatiou Gazette for Jan. 1897. Svo.

Machinery Market for Feb. 1897. Svo.

Nature for Feb. 1897. 4to.

New Book List for Feb. 1897. Svo.

New Church Magazine for Feb. 1897. Svo.

Nuovo Cimento for Jan. 1897. Svo.

Photographic News for Feb. 1897. Svo.

Science Sittings for Feb. 1897.

Transport for Jan. 1897. fol.

Travel for Feb. 1897.

Tropical Agriculturist for Feb. 1897.

Zoophilist for Feb. 1897. 4to.
Electrical Engineers, Institution of — Journal, Vol. XXV. No. 125. Svo. 1897.
Fitzgerald, Mrs. P. F. (the Author)— The Rational or Scientific Ideal of Morality.
Svo. 1897.

362 General Monthly Meeting [March 1,

Florence, Bihlioteca Nazionale Centrale — Bolletino, No. 266. 8vo. 1897.
Florence, Reale Aceademia dei Georgofili — Atti, Quarta Serie, Vol. XIX. Disp. 3,

4. Svo. 1896.
Franklin Institute — Journal for Feb. 1897. Svo.

Geographical Society, Royal — Geographical Journal for Feb. 1897. 8vo.
Geological Society — Quarterly Journal, No. 209. 8vo. 1897.
Quarterly Journal, General Index to first 50 vols. 8vo. 1897.
Geological Literature added to the Library during 1896. 8vo. 1897.
Harvard College— Annual Reports, 1895-96. 8vo. 1897.
Heneagef Charles, Esq. M.R.I. — Lecture on Psychiatric Institutions, the Austrian

Law of Curatel and separate Asylum for Drunkenness. By Herr Schlangen-

hausen.
Illinois, State Laboratory of Natural Eidory — Bulletin, Vol. IV. Part 2. Svo.

1896.
Report on Noxious and Beneficial Insects. Svo. 1898.
Imperial Institute — Imperial Institute Journal for Feb. 1897.
Iowa, State University — Bulletin from the Laboratories of Natural History,

Vol. IV. No. 1. Svo. 1896.
Iron and Steel Institute— J oumfd, 1896, No. 2. Svo. 1897.
Johns Hopkins University — American Chemical Journal, Vol. XIX. No. 2. Svo.

1897.
University Studies: Fifteenth Series, Nos. 1, 2. Svo. 1897.
Kerntler, Franz {the Author) — Die Elektrodynamischen Grundgesetze und das

eigentliche Elementargesetz, etc. Svo. 1897.
Leipzig, Fiirstlich Jahlonowskische Geselhchaft — Preisschriften,No. 34. Svo. 1896.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Vol.

XLI. Part 2. Svo. 1896-97.
Massachusetts State Board of Health — Twenty-fourth and Twenty-fifth Annual

Reports. Svo. 1893-94.
Mechanical Engineers, Institution of — Proceedings, 1896, No. 2. Svo.
Meteorological Society — Quarterly Journal, No. 10 L Svo. 1897.
Mitchell & Co. Messrs. (the Publishers) — ISewspaper Press Directory for 1897. Svo.
Navy League — Navy League Journal for Feb, 1897. Svo.
New Jersey, Geological Survey of — Annual Report of State Geologist for 1895.

Svo. 1896.
New Zealand, Registrar-General of — Statistics of the Colony of New Zealand for

1895. fol. 1896.
Numismatic Society — Numismatic Chronicle and Journal, 1896, Part 4. Svo.
Odontological Society of Great Britain — Transactions, Vol. XXIX. No. 4. Svo.

1897.
Onnes, D. H. K. — Communications from the Laboratory of Physics at the Univer-
sity of Leiden, No. 33. Svo. 1896.
Paris, Societe Frangaise de Physique — Bulletin, No. 89. Svo. 1897.
Pharmaceutical Society of Great Britain — Journal for Feb. 1897. Svo.
Philadelphia, Academy of Natural Sciences — Proceedings, 1896, Part 2. Svo.
Philadelphia, Geographical (7Zm&— Bulletin, Vol. II. No. 2. Svo. 1896.
Photographic Society, Royal — Photographic Journal for Jan.-Feb. 1897. Svo.
Physical Society of London — Proceedings, Vol. XV. Part 2. Svo. 1897.
Prince, C L. F.R.A.S. {the Compiler) — The Summary of a Meteorological Journal

for 1896. Svo.
Royal Irish Academy — Proceedings, Third Series, Vol. IV. No. 1. Svo. 1896.
Royal Society of Edinburgh— Froceedings, Vol. XXI. No. 3. Svo. 1S97.
Royal Society of London — Proceedings, Nos. 365, 366. Svo. 1897.

Philosophical Transactions, Vol. CLXXXVII. A. No. 188 ; Vol. CLXXXIX. A.

No. 189. 4to. 1897.
Saxon Society of Sciences, Royal —
Philoloqisch-Historische Clause —

Abhandlungen, Band XVI. ; Band XVIII. No. 1. Svo. 1897.
Mathematisch-Physische Classe —

Berichte, 1896, No. 4. Svo. 1897.

1897.] General Monthly Meeting. 353

Schooling, William, Esq. M.R.I, (the Author) — Life Assurance Explained. 8vo.

1897.
Selborne Society — Nature Notes for Feb. 1897. 8vo,

Society of Antiquaries — Proceedings, 2nd Series, Vol. XVI. No. 2. 8vo. 1896.
An Archaeological Survey of Lancashire. By Wm. Harrison. 4to. 1896.
An Archaeological Survey of Herefordshire. By J. O. Bevan and others. 4to.
1896.
Society of Arts — Journal for Feb. 1897. 8vo.
St. Petersburg, Academie Imperiale des Sciences — Bulletin, V® Serie, Tome VI.

No. 1. 8vo. 1S97.
United Service Institution, Boyal — Journal, No. 228. 8vo, 1897.
United States Department of Agriculture — Monthly "Weather Keview for Nov.
1896. 8vo.
Weather Bureau Bulletin, No. 19. 8vo. 1896.
Experiment Station Bulletin, Nos. 34, 35. 8vo. 1896.
United States Patent Oj^ce— Official Gazette, Vol. LXXVI. Nos. 12, 13 ; Vol.
LXXVII. Nos. 1-8. 8vo. 1896.
Alphabetical Lists of Patentees and Inventions for quarter ending March and
June, 1896. 8vo. 1896.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1897,

Heft 1. 4to.
Vienna, Impericd Geological Institute — Verhandlungen, 1896, Nos. 16-18. 8vo.
Waller, Professor Augustus D. M.D. F.R.S. M.i^.Z.— Electro-Physiology. By W
Biedermann. Translated by F. A. Welby. Vol. I. 8vo. 1896.

354 Mr. Shelford Bidwell [March 5,

WEEKLY EVENING MEETING,

Friday, March 5, 1897.

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Honorary
Secretary and Vice-President, in the Chair.

Shelford Bidwell, Esq. M.A. LL.B. F.R.S. M.R.L

Some Curiosities of Vision.

The function of the eye, regarded as an optical instrument, is limited
to the formation of luminous images upon the retina. From a purely
physical point of view it is a simple enough piece of apparatus, and,
as was forcibly pointed out by Helmholtz, it is subject to a number of
defects which can be demonstrated by the simplest tests, and which
would, in a shop-bought instrument, be considered intolerable.

What takes jjlace in the retina itself under luminous excitation,
and how the sensation of sight is produced, are questions which
belong to the sciences of physiology and psychology ; and in the
physiological and psychological departments of the visual machinery
we meet with an additional host of objectionable peculiarities from
which any humanly constructed apparatus is by the nature of the case
free.

Yet in spite of all these drawbacks our eyes do us excellent
service, and provided that they are free from actual malformation and
have not suffered from injmy or disease, we do not often find fault
with them. This, however, is not because they are as good as they
might be, but because with incessant practice we have acquired a very
high (iegree of skill in their use. If anything is more remarkable
than the ease and certainty with which we have learnt to interpret
ocular indications when they are in some sort of conformity with ex-
ternal objects, it is the pertinacity with which we refuse to be misled
when our eyes are doing their best to deceive us. In our earliest
years we began to find out that we must not believe all we saw :
experience gradually taught us that on certain points and under
certain circumstances the indications of our organs of vision were
uniformly meaningless or fallacious, and we soon discovered that it
would save us trouble and add to the comfort of life if we cultivated
a habit of completely ignoring all such visual sensations as were of
no practical value. In this most of us have been remarkably suc-
cessful, so much so that, if from motives of curiosity or for the sake
of scientific experiment, we wish to direct our attention to the sensa-
tions in question and to see things as they actually appear, we can

1897.1 on Some Curiosities of Vision. 355

only do so with the greatest difficulty ; sometimes, indeed, not at all,
unless with the assistance of some specially contrived artifice.

I propose to-night to discuss a few of the less familiar vagaries of
the visual organs, and will do my best to assist in the illustration of
them. But it will be my part merely to provide the apparatus for
the experiments ; the experiments themselves must be carried out by
each of you individually. Some of them will, I am afraid, be found
rather difficult ; success will depend mainly upon your power of
laying aside habit and prejudice and giving close attention to your
visual sensations. I hardly dare to hope that every one present will
observe all the peculiarities and defects which it is intended to
demonstrate, but in case of failure I generally find that there is a
comfortable tendency to attribute it not to any deficiency in the
observer's power of concentrating his attention, but to the fact that
his eyes are not as other mens', and are free from the particular defect
which it is desired to bring into prominence. Of course any one is
welcome to such an entirely satisfactory opinion.

Among the most annoying of the eccentricities which characterise
the sense of vision is that known as the persistence of impressions.
The sensation of sight which is produced by an illuminated object does
not cease at the moment when the exciting cause is removed or changed
in position, but continues for a period which is generally said to be
about ^Q second, but may sometimes be much more or less. It is for
this reason that we cannot see the details of anything which is in
rapid motion, but only an indistinct blur, resulting from the confu-
sion of successive impressions. When I turn this disc, which is
painted in black and white sectors, you soon lose sight of the
divisions, and if the speed is high enough the w^hole surface appears
to be of a uniformly grey hue. If we illuminate the rotating disc
by a properly timed series of electric flashes, it looks as if it were at
rest, and in spite of the intermittent nature of the light, the black and
white sectors are seen quite continuously, though as a matter of fact
the intervals of darkness are very much longer than those of
illumination.

The persistent impressions which we have been discussing are
often spoken of as positive after-images.

There is one very remarkable phenomenon accompanying the
formation of positive after-images, especially those following brief
illumination, which seems, until comparatively recent times, to have
entirely escaped the notice of the most acute observers. It was first
observed accidentally by Prof. C. A. Young, when he was experiment-
ing with a large electrical machine which had been newly acquired
for his laboratory. He noticed that when a powerful Leydeu jar
discharge took place in a darkened room, any conspicuous object was
seen twice at least, with an interval of a trifle less than a quarter of a
second, the first time vividly, the second time faintly. Often it was
seen a third time, and sometimes, but only with great difficulty, even a
fourth time. He gave to this phenomenon the name of recurrent

356

Mr. STielford Bidwell

[March 5,

vision : it may perhaps be more appropriately denominated the
Young effect.

We have here a machine presented to the Institution by Mr.
Wimshurst, which is a giant in comparison with that used by Prof.
Young, and I hope by its means to be able to show the effect to every
one present who will give a little attention. Look in the direction of
some object which is exposed to the light of the discharge : the object
will be seen for an instant at the moment when the spark passes and
you hear the crack, and after a dark interval of about ^ second it will
make another brief appearance. Some of you may perhaps see even
a second recurrent image. Under certain conditions I myself have
observed no less than six reappearances of an object which was
illuminated by a single discharge.

Twelve years ago I called attention to a very different method of
exhibiting a recurrent image. The apparatus used for the purpose
_ consists of a vacuum tube mounted in the usual

way upon a horizontal axis capable of rotation.
"When the tube is illuminated by a rapid suc-
cession of discharges from an induction coil, and
is made to rotate very slowly (at the rate of
about one turn in two or three seconds) a very
curious phenomenon may be noticed. At a
distance of a few degrees behind the tube, and
separated from it by a clear interval of darkness,
comes a ghost. This ghost is in form an exact
reproduction of the tube ; it is very clearly de-
hned, and though its apparent luminosity is
feeble, it can no doubt be easily seen by most
of you. The varied colours of the original are,
however, absent, the whole of the phantom tube
being of a uniform bluish or violet tint. If the
rotation is suddenly stopped, the ghost still
moves steadily on until it reaches the luminous
tube, with which it coalesces and so disappears.
(See Fig. 1, where the recurrent image is indi-
cated by dotted lines.)
. I returned to the subject three or four years

ago, with the pnmg^^y ^^y^JQ^.^ ^f ascertaining whether or not the Young
effect was identical with one which had recently been discovered by
Charpentier, and which will be referred to presently. A certain
phenomenon which I had attributed to the Young effect was quoted
by Charpentier as exemplifying his own newly-observed one. I
found, however, that the two effects, though both of an oscillatory
character, were in fact quite distinct from one another. The results
of my experiments in relation to this and other allied matters were
embodied in a communication to the Royal Society.*

Fig. 1.

Proc. Roy. Soc. vol. Ivi. p. 132 (1894).

1897.] on Some Curiosities of Vision. 357

In investigating the influence of colour upon the Young effect,
two methods of experimenting were employed. In the first, coloured
light was obtained by passing white light through coloured glasses ;
in the second and more perfect series of experiments, the pure
coloured light of the spectrum was used. Among otlicr results, it
was found that ceteris paribus the recurrent image was much stronger
-with green light than with any other, and that when the excitation
was produced by pure red light, however intense, there was no
recurrent image at all.

I intend to attempt a repetition of my first experiment before
you. A metal disc with a small circular aperture near its edge is
placed in the lantern, and its image projected upon the screen.
When the disc is turned slowly the sj)ot of light upon the screen
goes round and round, and some of you may, perhaps, be able to see
at once that the bright primary spot apj)ears to be followed at a short
distance by a much feebler spot of a violet colour, which is the re-
current image of the first. It is essential
to keep the direction of the eyes per-
fectly steady, which is not an easy thing
to do without practice. (See Fig. 2.) If
now we place a green glass before the
lens, the ghost will be at its best, and
all of you should be able to see it, pro-
vided that you do not look at it. With
an orange glass the ghost becomes less
distinctly visible, and its colour generally
appears to be bluish-green instead of
violet as before. When a red glass is
substituted the ghost completely disaj^-
pears. If the speed of rotation is suf- -pio 2

ficiently high, the red spot is considerably

elongated during its revolution, and its colour ceases to be uniform,
the rear portion assuming a light bluish-pink tmge. But however
great the speed, no complete separation of the spot into red and pink
portions can be effected, and no recurrent image is ever formed.

The spectrum method of observation can only be carried out on 8
small scale, and cannot be exhibited to an audience. It, however,
affords the best means of ascertaining hovf far the apparent colour of
the recurrent image depends upon that of the primary, a matter of
some theoretical interest. I found that white light was followed by a
violet recurrent image ; after blue and green, when the image was
brightest, its colour was also violet ; after yellow and orange it
appeared blue or greenish-blue. On the other hand, when a complete
spectrum was caused to revolve upon the screen, the whole of its
recurrent image from end to end appeared violet; there was no
appearance of blue or greenish-blue at the less refrangible end. For
this and other reasons it was concluded that the true colour was in
all cases really violet, the blue and greenish-blue apparently seen in
Vol. XV. (No. 91.) 2 b

358 Mr. SM/ord Bidwell [March 5,

conjunction with the much brighter yellow and orange of the primary
being merely an illusory effect of contrast. [This contrast effect was
illustrated by a lantern slide.] It seems likely, then, that the effect
which has been spoken of as recurrent vision, is due principally, if
not entirely, to an action of the violet nerve fibres. It need hardly
be pointed out that it represents only a transient phase of the well
known positive after-image, and it had even been observed in a vague
and uncertain sort of way long before the date of Prof. Young's
experiment. Helmholtz, for example, mentions the case of o positive
after-image which seemed to disappear and then to brighten up
again ; but he goes on to explain that the seeming disappearance was
illusory.

M. Charpentier, of Nancy, whose name I have already mentioned,
was the first to notice and record a remarkable phenomenon which,
in some form or other, must present itself many times daily to

every person who is not blind, but
which, until about six years ago, had
been absolutely and universally ignored.
The law which is associated with Char-
pentier's name is this : — When darkness
is followed by light, the stimulus which
the retina at first receives, and which
causes the sensation of luminosity, is
succeeded by a brief period of in-
sensibility, resulting in the sensation of
momentary darkness. It appears that
the dark period begins about -^q^ second
after the light has first been admitted
Fig. 3. to the eye, and lasts for about an equal

time. The whole alternation from light
to darkness and back again to light is performed so rapidly, that
except under certain conditions, which, however, occur frequently
enough, it cannot be detected.

The apparatus which Charpentier employed for demonstrating
and measuring the duration of this effect is very simple. It consists
of a blackened disc with a white sector mounted upon an axis. When
the disc is illuminated by sunlight and turned rather slowly, there
appears upon the white sector close behind its leading edge a narrow
but well-defined dark band (See Fig. 3). The portion of the retina
which is apparently occupied at any moment by the dark band is
that upon which the light reflected by the leading edge of the white
sector has fallen -J-^ second previously.

But no special apparatus is required to show the dark reaction ;
it is, as I have said, an exceedingly common phenomenon. In Fig. 4
an attempt has been made to illustrate what any one may see if he
simply moves his hand between his eyes and the sky or any strongly
illuminated white surface. The hand appears to be followed by a
dark outline separated from it by a bright interval. The same kind

1897.] on Some Curiosities of Vision. 359

of thing happens in a more or less marked degree whenever a dark
object moves across a bright background, or a bright object across a
dark background.

In order to see the effect distinctly by Charpentier's original
method, the illumination must be strong. If, however, the arrange-
ment is slightly varied, so that transmitted instead of reflected light
is made use of, comparatively feeble illumination is sufficient. A
very effective way is to turn a small metal disc having an open
sector of about 60°, in front of a sheet of ground or opal glass behind
which is a lamp. By an arrangement of this kind upon a larger
scale, the effect may easily be rendered visible to an audience. The
eyes should not be allowed to follow the disc in its rotation, but
sJaould be directed steadily upon the centre. [Experiment.]

The acute and educated vision of Charpentier enabled him, even
when working with his black and white disc, to detect the existence.

Fig. 4. Fig. 5.

under favourable conditions, of a second, and sometimes a third dark
band of greatly diminished intensity, though he remarks that the
observation is a very difficult one. What is probably the same effect
can, however, be shown quite easily in a different manner. If a disc
with a very narrow radial slit J^ inch or J mm. wide, is caused to
rotate at the rate of about one turn per second in front of a bright
background, such as a sheet of ground glass with a lamp behind it,
the moving slit assumes the appearance of a fan-shaped luminous
patch, the brightness of which diminishes with the distance from the
leading edge. And if the eyes are steadily fixed upon the centre of
the disc, it will be noticed that this bright image is streaked with a
number of dark radial bands, suggestive of the ribs or sticks of the
fan. Near the circumference as many as four or five such dark
streaks can be distinguished without difficulty; towards the centre
they are less conspicuous, owing to the overlapping of the successive

2 B 2

360 Mr. Shelf ord Bidwell [March 5,

images of the slit.* [The effect was demonstrated by means of a
rotating disc in the lantern, and is roughly indicated in Fig. 5.]

The dark reaction known as the Charpentier effect, occurs at the
beginning of a period of illumination. There is also a dark reaction
of very short duration at the end of a period of illumination. I
should explain that owing to what is called the proper light of the
retina, ordinary darkness does not appear absolutely black : even in
a dark room on a dark night with the eyes carefully covered, there
is always some sensation of luminosity which would be sufficient to
show up a really black image if one could be produced. Now the
darkness which is experienced after the extinction of a light is for a
small fraction of a second more intense than common darkness.

I believe that the first mention of this dark reaction occurs in the
article which I contributed to ' Nature ' in 1885, in which it was stated
that when the current was cut off from an illuminated vacuum
tube " the luminous image was almost instantly replaced by a corre-
sponding image which appeared to be intensely black upon a less dark
background," and which was estimated to last from J to J second.
" Abnormal darkness," it was added, " follows as a reaction after the
luminosity."

In the Royal Society paper to which I have before referred the
point is further discussed, and a method is described by which the

stage of reaction may be easily exhibited,
and its duration approximately measured.
If a translucent disc made of stout
drawing-paper and having an open
sector, is caused to rotate slowly in
front of a luminous background, a
narrow radial dark band like a streak
of black paint appears upon the paper
very near the edge which follows the
open sector. From the space covered
by this band when the disc was rotating
at a known speed, the duration of the
dark reaction was estimated to be about
■5-^^ second. [The experiment was shown,
Fig. 6. and is illustrated in Fig. C]

One more interesting point should
be noticed in the train of visual phenomena which attend a period of
illumination. The sensation of luminosity which is excited when light
first strikes the eye is for about ^L second much more intense than it
subsequently becomes. This is shown by the fact that the bright
band intervening between the leading edge of the white sector of a
Charpentier disc and the dark band, appears to be much more
strongly illuminated than any other portion of the sector.

* Proc. Roy. Soc, vol. Ivi. p. 142 (1894). A similar observation was described
by Charpentier, Comptes Rendus, Jan. 1896.

1897.] on Some Curiosities of Vision. 361

I propose now to say a few words about a curious phenomenon
of vision wbicli occupied my attention towards the end of hist year.*

Eather more than two years ago, Mr. C. E. Benham brought out
a pretty little toy which he called the Artificial Spectrum Top. It
consists of a cardboard disc, one half of which is painted black, while
on the other half are drawn four successive groups of concentric
black lines at different distances from the centre. When the disc
rotates rather slowly each group of black lines generally appears to
assume a different colour, the nature of which depends upon the speed
of the rotation and the intensity and quality of the light. Under
the best conditions the inner and outer groups of lines become
bright red and dark blue ; at the same time the intermediate groups
also appear tinted, but the hues which they assume are rather un-
certain and difficult to specify. By far the most striking of the
colours exhibited by the top is the red, and next to that the blue ;
this latter, however, is sometimes described as bluish-green. [The
top was exhibited as a lantern slide.]

My recent experiments seem to indicate pretty clearly the cause
of the remarkable bright red colour and also that of the blue. The
more feeble tints of the two intermediate groups of lines perhaps
result from similar causes in a modified form, but these I have not
yet investigated.

In the red colour we have another striking example of an ex-
ceedingly common phenomenon which is habitually disregarded ;
indeed, I can find no record of its ever having been noticed at all.
The fact is, that whenever a bright image is suddenly formed upon
the retina after a period of comparative darkness, this image appears
for a short time to be surrounded by a narrow coloured border, the
colour under ordinary conditions of illumination being red. If the
light is very strong the transient border is greenish-blue. Sometimes
both red and blue borders appear together, the blue being inside the
red.t The colour generally seen is, however, red, and it is most
conspicuous with good lamp-light.

This observation was first made in the following manner. A
blackened zinc plate with a small round hole in it is fixed over a
larger hole in a wooden board ; the hole in the zinc is covered with
a piece of thin white writing paper. Thus we are furnished with a
sharply defined translucent disc which is surrounded by a perfectly
opaque substance. An arrangement is made for covering the trans-
lucent disc with a shutter which can be opened very rapidly by
means of a strong spring. If this apparatus is held between the
eyes and a lamp, and the translucent disc is suddenly disclosed by
working the shutter, the disc appears for a short time to be sur-
rounded by a narrow red border. The width of the border is perhaps

* Proc. Koy. Soc. vol. Ix. p. 370 (1896).

t I have recently shown that the greenish-blue border is simply the " negative
after-image " of the red one. — April 24th.

362 Mr. Shelf ord Bidwell [March 5,

-^ inch or 1 mm., and the appearance lasts for something like
ytj. second. Most people are at first quite unable to recognise this
effect, the difficulty being not to see it but to know that one sees it.
Those who have been accustomed to visual observations generally
perceive it without any difficulty when they know what to look for,
and no doubt it would be quite evident to a baby a few weeks old,
which had not advanced very far in the education of its eyes.

The observation is made rather less difficult by a further device.
If the disc^ is divided into two parts by an opaque strip across the
middle, it is clear that each half-disc will have its red border, and, if
the strip is made sufficiently narrow, the red borders along its edges
will meet, or perhaps overlap, and the whole strip will, for a moment
after the shutter is opened, appear red. A disc was prepared by
gumming across the paper a strip of tin foil about 3L inch wide.
The effect produced when such a disc is exposed is indicated in
Fig. 7, the red colour being represented by shading.

Fig. 7.

A simpler apparatus is, however, quite sufficient for showing the
effect,* and with practice one can even acquire the power of seeing it
without any artificial aid at all. I have many times noticed flashes of
red upon the black letters of a book that I was reading, or upon the
edges of a page : bright metallic or polished objects often show it
when they pass across the field of vision in consequence of a move-
ment of the eyes, and it was an accidental observation of this kind
which suggested the following easy way of exhibiting the effect
experimentally.

An electric lamp was fixed behind a round hole in a sheet of
metal which was attached to a board. The hole was covered with
two or three thicknesses of writing paper, making a bright disc of
nearly uniform luminosity. When this was moved rather quickly
either backwards or forwards or round and roimd in a small circle,

* See ' Nature,' vol. Iv. p. 367 (Feb. 18, 1897).

1897.] on Some Curiosities of Vision. 363

the edges of the streak of light thus formed appeared to be bordered
with red. [Experiment shown. J

If this experiment is performed with a strong light, the hole
becomes bordered with greenish-blue instead of red. With an inter-
mediate degree of illumination both blue and red may be seen together,
the blue being inside the red.

Most of the effects that have so far been described were produced
by transmitted light, but reflected light will show them equally well.
If you place a printed book before you near a good lamp and inter-
pose a dark screen before your eyes, then, when the screen is suddenly
withdrawn, the printed letters will for a moment appear red, quickly
changing to black. Some practice is required before this observation
can be made satisfactorily, but by a simple device it is possible to
obliterate the image of the letters before the redness has had time to
disappear ; the colour then becomes quite easily perceptible. Hold
two screens together side by side, a black one and a white one,
in such a manner that there is a triangular opening left between
them. In the first place let the black screen cover the printing, then
quickly move the screens sideways so that the printed letters may be
for a moment exposed to view through the gap, stopping the move-
ment as soon as the page is covered by the white screen. During
the brief glimpse that will be had of the black letters while they are
beneath the gap, they will, if the illumination is suitable, appear to
be bright red.

We may go a step further. Cut out a disc of white cardboard,
divide it into two equal parts by a straight line through the centre,
and paint one half black. At the .^«^____

junction of the black and white portions ^^ ^

cut out a gap which may conveniently
be of the form of a sector of about 45°
(see Fig. 8). Stick a long pin through
the centre and hold the arrangement
by the pointed end of the pin a few
inches above a printed page near a
good light. Make the disc spin at the
rate of about 5 or 6 turns a second
by striking the edge with the finger.
As before, the letters when seen through
the gap will appear red, and persistence
will render the repeated impressions
almost continuous. Care must be taken Fig. 8.

that the disc does not cast a shadow

upon the printing, and that the intensity of the illumination is properly
adjusted. I have here several rather more elaborate contrivances for
making discs rotate.

In none of these experiments does an extended black surface ever
appear red, but only black dots or lines, which may of course have the
form of letters. And the lines must not be too thick ; if their thick-

364 Mr. Shelford Bidwell [March 5,

ness is much more than gV ^^^^ ^^ ^ ^^' ^^® lines, as seen by an
observer at a distance of two or three feet, do not become red through-
out but only along their edges. The red appearance is in fact not
due to the black lines themselves at all ; these serve merely as a
background for showing up the red border which fringes externally
the white portions of the paper, and the width of this border does not
exceed about one-fifth of a degree.

[By means of a large rotating disc some designs in black lines and
letters were made to appear red, the effect being visible in all parts of
the theatre.]

When the disc is turned in the opposite direction, the black lines
appear at first sight to become dark blue. Attentive observation,
however, shows that the aj^parently blue tint is not formed upon the
lines themselves as the red tint was, but upon the white ground just
outside them. This introduces to our notice another border phe-
nomenon which seems to present itself when a dark patch is suddenly

Fig. 9.

formed on a bright ground, for that is essentially what takes place
when the disc is turned the reverse way. I made some attempts to
obtain more direct evidence that such a dark patch appeared for a
moment to have a blue border, and after some trouble succeeded in
doing so.

A circular aperture was cut in a wooden board and covered with
white paper : a lamp was placed behind the board, and thus a bright
disc was obtained as in the former experiment. An arrangement was
prepared by means of which one half of this bright disc could be
suddenly covered by a metal shutter, and it was found that when
this was done a narrow blue band appeared on the bright ground just
beyond and adjoining the edge of the shutter when it had come to
rest. The blue band lasted for about -^^ second, and it seemed to
disappear by retreating into the black edge of the shutter. An
attempt has been made to illustrate it in Fig. 9, where the shaded
band indicates the blue border.

1897.] on Some Curiosities of Vision. 365

We have then to account, if possible, for the two facts that in the
formation of these transient borders the red sensation occurs in a
portion of the retina which has not been exposed to the direct action
of light, while the blue occurs in a portion which is exposed to un-
changed illumination. Accepting the Young-Helmholtz theory of
colour vision, the effects must, I think, be attributed to a sympathetic
affection of the red nerve fibres. When the various nerve fibres
occupying a limited portion of the retina are suddenly stimulated by
white or yellow light of moderate intensity, the immediately surround-
ing red nerve fibres are for a short period excited sympathetically,
while the violet and green fibres are not so excited, or in a much less
degree. And again, when light is suddenly cut off from a patch in a
bright field, there occurs an insensitive reaction in the red fibres just
outside the darkened patch, in virtue of which they cease for a
moment to respond to the luminous stimulus: the green and violet
fibres by continuing to respond uninterruptedly, give rise to the
sensation of a blue border.

Whether or not the hypothesis which I have suggested is correct
in all its details, it is, I think, sufficiently obvious that the red and
blue colours of Benham's top are due to exactly the same causes as
the colours observed in my own experiments, for the essential condi-
tions are the same in both cases.

I have mentioned only a few among many curious phenomena
which have presented themselves in the course of my investigation.
It is not improbable that a careful study of the subjective effects
produced by intermittent illumination would lead to results tending
to clear up many doubtful points in the theory of colour vision.

[S. B.]

366 Professor Arthur Smithells [March 12,

WEEKLY EVENING MEETING,
Friday, March 12, 1897.

Sib Frederick Abel, Bart. K.C.B. D.C.L. LL.D. F.E.S.
Vice-President, in the Chair.

Professor Arthur Smithells, B.Sc. F.I.C.

The Source of Light in Flames.

When hydrogen burns in oxygen the gases unite to form steam, and
a flame of simple structure is obtained. The light is of very feeble
intensity, so feeble when the hydrogen is highly purified and when
both gases are free from dust, that the flame is scarcely visible in a
room from which all other light is excluded.*

To what is the light of this flame due ? It is not sufficient to
say that it is the result of chemical action attended by the evolution
of much heat. Light is of an undulatory nature, and the undulations
arise during an oscillatory process associated with matter. We
desire to know with what particular kind of atoms or molecules the
light of a hydrogen flame is associated. It may be said that when
hydrogen combines with oxygen the heat that is produced is
necessarily contained, as it were, in the steam, and that therefore it
is the steam that glows. This raises the question as to what evidence
we have, apart from flames, of the possibility of making gases glow
by the simple process of heating them. The evidence is nearly all
negative. None of the common gases, including those contained in
the best known flames, have been made to glow when heated by a
2)urely baking or roasting process to the highest obtainable tempera-
ture. The passage of an electric discharge through the gases is not
to be regarded as merely a heating process.

Aii^ong the gases that can be made to glow, the most conspicuous
is iodine. The vapour of this substance shows a distinct red glow at
a temperature below that at which glass is visibly red.l [Experi-
ment shown.] It is possible that some chemical action, namely,
dissociation and recombination, may be in progress in the iodine
vapour, and that the emission of light may be due to this. A similar
glow, however, has been obtained with bromine, and, to a less extent,
with chlorine,^ at temperatures which exclude the likelihood of
dissociation.

* Stas, CEuvres, tome iii. p, 228.

t Salet, ' Analyse Spectrale,' p. 173 ; see also Phil. Mag, [v] 37, p. 245 (1894).

X Evershed, Phil. Mag. [v] 39, p. 460 (1895).

1897.] on the Source of Light in Flames. 367

The great difficulty, and in most eases the present impossibility,
of making gases glow by a mere increase of temperature of a direct
kind, leads us to hesitate before we say that a hydrogen flame glows
merely because it contains hot steam. The matter may be con-
sidered from another point of view. When hydrogen burns, the
atoms of hydrogen are combining chemically with atoms of oxygen.
It is impossible to picture this process with any certainty of detail,
but we do know that the uncombined atoms have a store of energy
which is set free or becomes perceptibly kinetic when they combine.
This action takes place only when the atoms are within each other's
sphere of chemical attraction, or, in other words, when the new
substance begins to be formed. It seems impossible not to suppose
that such a process entails in the substance that is being formed a
condition as regards motion which must be considered apart from
any condition of temperature which is exhibited by the flame as a
whole. We cannot suppose, when a number of atoms commence to
form a molecular system, that the liberation of their potential energy
will result directly in increased translatory motion of the newly
formed molecule. The process may be compared to two oppositely
electrified spheres approaching one another rapidly in space in paths
sufficiently close for the mutual attraction to determine their union
into a system of revolution ending in actual contact. During the
coalescence the system would be in a vibratory state.

Without propounding any hypothesis as to the nature of chemical
energy, it seems certain that in the process of chemical union the
newly formed substance is in a state that it will be very difficult,
and perhaps even impossible, for it to acquire by what we ordinarily
understand as an increase of temperature, and this state being
oscillatory may well occasion the emission of light.

The oscillatory motion will be short lived and will disappear in
two ways, first in producing radiations, and secondly and chiefly, in
communicating to other impinging molecules, and thereby to itself,
an increased translatory motion which corresponds to increase of
temperature. According to this view the emission of light by a
burning gas is antecedent to, rather than consequent upon, a high
temperature, if we used this last term in its ordinary sense.

If the number of molecules being formed in a flame at any
instant is small compared with the number of other molecules in
their immediate neighbourhood, we may have a flame in which the
emission of light is associated with a low general temperature.
This case arises with substances that enter into combination freely at
low temperatures. A stream of carbon dioxide charged with a little
phosphorus vapour produces a bright green flame when it issues into
the air. The light is due to phosphoric oxide, that is to say, it is
the formation of phosphoric oxide that occasions it. Much energy
is liberated during the formation of each molecule, but the luminous
molecules are so far apart, there are so many molecules of carbon
dioxide round them, that the average temperature is quite incon-

368 Professor Arthur Smithells [March 12,

siderable, and the finger perceives no heat when held in the flame.
If the supply of phosphorus vapour be increased the number of
luminous molecules increases, the light becomes brighter, and the
temperature also rises in due proportion.

In the case of hydrogen, which does not ignite at a low tem-
perature, it is impossible to get a cool sheet of flame, for by the
addition of a neutral gas, the molecules of nascent steam are soon
separated to such an extent that the energy liberated is insufficient to
keep the general temperature of the sheet up to the j)oint required
to stimulate sufficiently the combination of the incoming hydrogen.

If the shell of burning gas, which constitutes what may be called
the foundation of a flame, is very hot, it is always possible that a
secondary source of light may be developed, due to a purely baking
process. This may affect the product of combustion itself, or the
unburned gas or some decomposition product. We might thus
anticipate that in the hydrogen flame light would come not only from
the steam, which is being formed, but also from the hydrogen within
the flame, which is subjected to intense roasting as it ascends.
This, however, does not appear to be the case. The occurrence of the
spectrum of hydrogen in that of the oxy-hydrogen flame was described
by Pliicker, but experiments undertaken by Professor Liveing,*
specially to test this question, have decided it in the negative. The
light of the oxy-hydrogen flame has been examined spectroscopically
by Professors Liveing and Dewar, Dr. Huggins and others, and the
spectrum is now attributed to water alone.

The light of a hydrogen flame is very feeble compared with that
of most other flames. If we ask why this is so, we are asking almost
the same question that eighty years ago impelled Sir Humphry Davy
to the splendid researches which laid the foundation of our scientific
knowledge of flames. And it was the same question that fifty years
later led Dr. Edward Frankland to investigations of flame, which
rank second only to those of his illustrious predecessor. Curious to
know why an explosive mixture of coal gas and air within a safety
lamp burned with a pale blue flame, whilst coal gas ordinarily burnt
with a bright light, Davy, after a few simple experiments, concluded
that he was correct in his first surmise, viz. " that the cause of the
superiority of the light from the stream of coal-gas might be owing
to a decomposition of a part of the gas towards the interior of the
flame where the air was in smallest quantity, and the deposition of
solid charcoal which, first by its ignition and afterwards by its
combustion, increased in a high degree the intensity of the light."
Davy's final and general conclusion was that '* whenever a flame is
remarkably brilliant or dense it may be always concluded that some
solid matter is produced in it ; on the contrary, when a flame is
extremely feeble and transparent it may be inferred that no solid
matter is formed."

* Phil. Mag. [v] 34, p. 371 (1892).

1897.] on the Source of Light in Flames. 369

In 1867 Dr. Frankland, lecturing before the Eoyal Institution,*
gave strong reasons for dissenting from Davy's views, both as to the
cause of the luminosity of flames in general and of the flames of
hydrocarbons in particular. Dr. Frankland's conclusions may be
summarised as follows : —

(i.) Bright flames exist which do not contain solid particles.

(ii.) The luminosity of flames depends mainly on the density of
the substances contained in them.

(iii.) Feebly luminous flames may be made bright by compressing
the burning gases.

(iv.) The luminosity of ordinary hydrocarbon flames, such as
that of coal gas, is not due in any important degree to solid particles
of carbon, but almost entirely to the glow of dense hydrocarbon
vapours.

Of these conclusions, two are beyond doubt. The flame of
phosphorus, or of carbon-di sulphide burning in oxygen, are examples
of bright flames in which no solid matter can be supposed reasonably
to exist. The explosion of electrolytic gas in a eudiometer resting
on an india-rubber pad produces a bright light, the gas is hindered
from expanding, and hence the flame travels through the mixture
under increasing pressure.

A table, in Dr. Frankland's paper, shows the kind of evidence
from which he concluded that the brightness of flames depends on
the density of the substances they contain, and the general agreement
of fact with theory is very striking. It is important to know whether
the rule holds without exception, and whether it is in harmony with
other general laws. There are flames containing dense substances
which are not bright, and flames which are bright though they do
not contain dense substances; but these apparent exceptions are
explained by supposing that the temperature in one case is very low
and in the other very high. If this kind of accommodation is per-
missible. Dr. Frankland's principle can hardly be submitted to a
rigorous test.

The fact that the light of compressed flames is so intense can
hardly be held to support the general doctrine in any rational sense,
for it cannot be said either physically or chemically that two gases
are in a like state when they have the same density. As a fact the
increased luminosity here accompanying increased density is unde-
niable, and Dr. Frankland has contended for no more than this ;
but the matter must be looked at in the light of the molecular theory.
This theory would lead us to expect increased light from a flame
containing dense matter if the density were a result of molecular
crowding, whilst it can at present tell us nothing about the effect
likely to ensue from an increase of density arising from the greater

* Proc. Roy. Inst. 5, p. 419. The best account of Dr. Frankland's views is
contained in six lectures delivered at the Royal Institution, and admirably
reported in the ' Journal of Gas Lighting.*

370 Professor Arthur SmitJiells [March 12,

weight of the individual molecules. For this reason Dr. Frankland's
observations on compressed flames may be considered essentially
unconnected with the observations on uncompressed flames containing
substances of high molecular weight, though the results may be
embodied in a single statement ; and to this extent the generalisation
loses importance.

The development of brightness in a flame may be conveniently
studied in the flame of hydrogen phosphide. When this gas is
sufficiently diluted with carbon dioxide, the flame has the same green
glow as has been already noticed in the case of carbon dioxide charged
with phosphorus vapour. This glow is to be ascribed to the forma-
tion of an oxide of phosphorus, and since phosphorus oxide itself
glows in presence of oxygen with exactly the same light,* we may
reasonably conclude that the oxide whose formation determines the
glow is the pentoxide. If now the proportion of hydrogen phosphide
to carbon dioxide be slightly increased, an entirely new kind of
luminosity is developed in the flame towards the tip. This is at first
yellowish, but increases in whiteness and brilliance as the supply of
carbon dioxide is diminished, until finally, when the pure hydride is
burning, the flame has the appearance of brightly burning phosj^horus.
This yellow or white light is to be regarded as secondary in origin,
and to be the result of high temperature in the ordinary sense of the
word. In confirmation of this it may be stated that the light appears
in exactly that place where, considering the flame as a heating agent,
the effective temperature would be highest ; and further, if a ring of
copper wire be placed horizontally in the lower part of the flame, so
as to lower the general temperature, the yellow luminosity at once
disappears just as it does when the flame is cooled by an increase in
the supply of carbon dioxide. It is a matter of much interest to
determine what substance emits the yellow or white light. It might
be supposed to be due to phosphorus separated within the flame by
decomposition of the hydrogen phosphide. In that case the introduc-
tion of oxygen into the middle of the flame might be expected to
diminish the luminosity ; but the reverse is the case. The glow
appears to be due to phosphorus pentoxide, for if the flame of a
Bunsen burner be held above the hydrogen phosphide flame the
yellow-white glow is extended continuously upwards into the Bunsen
flame. The track of the phosphorus pentoxide can in fact be seen in
the form of a white glow so long as the temperature of the surround-
ings reaches a certain point. The absence of solid particles from a
hydrogen phosphide flame can be shown by concentrating the sun's
rays upon it.

In these experiments the use of hydrogen phosphide gives a con-
venient method of regulating the supply of phosphorus ; they may be
repeated with phosphorus vapour itself diluted with carbon dioxide,
and the same results are obtained. It appears, therefore, that there

» Thorpe on 'The Glow of Phosphorus,' Proc. Roy, Inst. 13, p. 72 (1890).

1897.] on the Source of Light in Flames. 371

are two luminous effects to recognise in the combustion of phosphorus.
One is due to the act of formation of phosphorus pentoxide giving the
green glow, and the other due to the subsequent heating of the same
substance producing the white glow. Adopting the terminology
suggested by E. Wiedemann, we may say that there is chemi-lumines-
cence and thermo-luminescence of phosphorus pentoxide. In what is
ordinarily called the phosphorescence of phosphorus we have the
chemi-luminescence ; in the vivid combustion of phosphorus the
chemi-luminescence is completely overpowered and masked by
the thermo-luminescence.

It is interesting to inquire how far other combustible elements
behave in the same way. The flame of silicon hydride may be sub-
jected to similar experiments. When sufficiently diluted with carbon
dioxide a pale greenish flame is obtained, silica being the product.
The green colour may therefore be attributed to the formation of
this compound. When the supply of carbon dioxide is reduced the
flame becomes brightly luminous, but the luminosity may be removed
by cooling with a wire ring. The optical test shows the bright light
to be due to solid particles, and as the glow is prolonged continuously
in the track of the escaping silica when a Bunsen flame is held over
the silicon hydride flame, it seems clear that the secondary or bright
luminosity of the flame is here, as in the case of phosphorus, to be
ascribed to a purely thermal action. The chief difference in the two
instances is that in the case of phosphorus hydride the product is a
glowing gas, and in the case of silicon hydride a glowing solid.

Hydrocarbon flames may also be considered from the same point
of view, and here the facts are well known. In the first instance we
have to recognise in a hydrocarbon flame the bright yellow light
and the blue or lilac light. The bright yellow light may be
suppressed by cooling by means of a wire or by diluting the gas
with carbon dioxide. This part of the light of a hydrocarbon
flame has frequently been ascribed to a preferential burning of the
hydrogen, whereby carbon is separated in the flame and glows in
the state of solid particles. This view, which appears to have
originated in a misinterpretation of Davy's words, has never been
based on substantial evidence, and it is at variance with the most
cogent experiments on the subject. There seems little doubt that
the bright glow of a hydrocarbon flame is essentially a thermal
phenomenon.

The glowing substance was supposed by Davy to be solid
particles of carbon, by Frankland to be the vapour of dense hydro-
carbons. These two rival views have been subject to considerable
discussion, especially by Heumann.*

It seems extremely difficult now to find any good evidence for
the dense hydrocarbon theory. One of the simplest arguments
against it was supplied by Stein, who pointed out that the glowing

* Phil. Mag. [i] 89, p. 366 (1877).

372 Professor Arthur Smitliells [Marcli 12,

substance in a hydrocarbon flame, which may be collected in the
form of soot, contains a smaller quantity of hydrogen than could
reasonably be expected if soot were a hydrocarbon or a mixture of
hydrocarbons. He also remarked upon the non-volatile character
of soot. A recent analysis of soot from an acetylene flame showed
1*4 parts of hydrogen to 98*6 parts of carbon, after the soot had
been extracted with ether and dried. Now the hydrocarbon richest
in carbon recognised in organic chemistry (chrysogene) contains
about 5 per cent, of hydrogen. The soot, therefore, could not con-
tain more than about 30 j)er cent, of it, leaving a surplus of 70 per
cent, of uncombined carbon. To maintain Frankland's doctrine
that the light is essentially due to dense hydrocarbons in the gaseous
state, would compel us, in fact, to recognise soot as a hydrocarbon
of quite exceptional composition and properties. The doctrine was,
in its inception, an inference from experiments on other flames in
which high luminosity was found to be associated with high density
of the substances contained in the flames ; but it is to be remarked
that in most, if not all of these flames, the glow was ascribed to the
product of oxidation, and not merely to something separated and
subjected to a purely roasting process.

But even if we regard the glowing substance soot of a flame as a
hydrocarbon or a mixture of hydrocarbons, and to this extent accept
Frankland's view, there remains the question whether the glowing
substance in the flame is solid or gaseous. The optical test, first
used by Soret, shows indisputably that a finely divided solid pervades
the whole of the luminous region of a hydrocarbon flame, and there
seems no reason to doubt that the glow of this solid matter would be
adequate to produce the light of the flame.

According to the views of Lewes, the luminosity of a hydrocarbon
flame is determined essentially by the formation and subsequent
decomposition of acetylene. This theory, which is certainly in-
genious, need not be discussed on the present occasion.

The development of bright light in a hydrocarbon flame, what-
ever be the full explanation, is certainly a secondary process,
demanding a particular mode of burning the gas for its production.
When the hydrocarbon meets the air in other ways, as when it is
burnt in a very small flame or at a very high pressure, or when air
is added to the gas before it leaves the burner, the bright light
disappears, and we then have the primary light of combustion which
is of feeble intensity and blue colour. The changes which a hydro-
carbon flame undergoes with varying air supply are well seen when
benzene vapoar is burned with a gradually increasing quantity of
admixed air. The flame is at first very bright; the next phase,
reached when the bright yellowish light has just disappeared, shows
two cones of bluish light, corresponding to those of a Bunsen burner ;
the last phase is reached when, by adding more air, the outer cone
is quenched, and the flame presents the appearance of a thin conical
shell of blue light. [Experiment shown.] The two-coned phase

1897.] on the Source of Light in Flames. 373

marks the period when the oxygen required for combustion is got
partly from the air mixed with the vapour before it leaves the burner
and partly from the air outside, one cone corresponding to each part
of the supply. From analyses of the interconal gases, it appears that
large quantities of carbon monoxide and hydrogen are generated in
the inner cone, and that these are the gases which burn in the outer
cone. The evidence that the formation of carbon monoxide is the first
step in the combustion of carbon has been greatly strengthened by
the experiments of Prof. H. B. Dixon, and is at variance with no
important facts.

The source of the light in a blue-burning hydrocarbon flame has
been the subject of most elaborate investigation and of prolonged
controversy. The spectrum of this light was one of the first to be
carefully described, and is often called the Swan spectrum, from
the fact that it was first accurately mapped by Swan in 1856. It
is seen in the blue part at the base of all ordinary hydrocarbon
flames and in the inner cone, but not in the outer cone of flames fed
with air in the manner of the Bunsen burner. In so far as the charac-
teristic ijroduct of these jiarts of flumes has been found to be carbonic
oxide, it would be natural to attribute tlie Swan spectrum to this gas.
This view, however, has never been adopted. The Swan spectrum
has been attributed either to carbon itself or to a hydrocarbon (acety-
lene), and the whole discussion and investigation of the subject has
centred round these alternatives. The neglect to consider the likeli-
hood of carbon monoxide being the source has arisen from a disregard
of the occurrence of this gas in flames, and from a belief that it has
another distinct spectrum. At the same time the difficulty presented
by the other explanations has been fully realised, and it is admitted
that the support of either demands somewhat strained hypotheses.

The question of the origin of the Swan SiDcctrum is too large and
complicated to be fully discussed here. It will suffice to j)oint out
that if the formation of carbon monoxide is the first act in the oxida-
tion of a hydrocarbon two results would follow : (1) it would hardly
be supposed that carbon vapour existed free even momentarily in the
flame; (2) that the preponderating product with which was associated
the energy of the chemical change should contribute mainly to the
emission of light. The chief difficulty opposed to the view that
carbon monoxide is really the source of the Swan spectrum appears
to lie in the fact that this gas may be made to yield a different spec-
trum by the electric discharge. A full consideration of the evidence
bearing on the subject leads to the view, first, that this spectrum is
not undoubtedly due to carbon monoxide, and secondly, that it may
be due to carbon dioxide.

The evidence derived from the study of flames, and much other
evidence, is favourable to the view that carbon monoxide is the source
of the Swan spectrum, and if this be the case, the chemi-luminescence
of a hydrocarbon flame like that of a flame of the hydrides of j^hos-
phorus, silica and antimony, would be attributed to the act of oxidation.

Vol. XV. (No. 91.) 2 c

374 Prof. Smithells on the Source of Light in Flames. [March 12,

Some light is no doubt due to the completion of the oxidation, the
carbon monoxide forming carbon dioxide and the hydrogen forming
water, but the intensity of this portion of the light is inconsiderable
in the spectroscope, and in the visible spectrum not characteristic.

The flame of cyanogen presents special points of interest. It has
been shown that the sharp differentiation of the flame into an inner
rose-coloured cone and an outer blue one, corresponds to the combus-
tion of the gas in two steps, the first being the oxidation of carbon, to
carbon monoxide, and the second the oxidation of carbon monoxide to
carbon dioxide.* Admixture of air with the gas before combustion
renders it possible to separate the two parts of the flame in the cone
separating apparatus, and when the distance between them exceeds a
certain limit and the gases are dried, the outer cone is quenchfid wlien
a bottle of dried air is held over it. [Experiment shown.] This
behaviour accords with the well known experiment of Prof. Dixon on
the combustion of carbon monoxide. According to the view which has
been developed in the foregoing, it would be expected that the light
emitted by the inner cone of a cyanogen flame should be due to the
carbon monoxide which is produced there, and if the Swan spectrum
be really due to that substance then the Swan spectrum should be
Been. As a matter of fact, the inner cone of a cyanogen flame gives a
brilliant spectrum, in which, however, only one band of the Swan
spectrum is distinctly developed. It is possible that the liberation of
nitrogen from cyanogen during its combustion may have a disturbing
influence. In any case it is very striking that when cyanogen is
burnt in oxygen instead of air the Swan spectrum is seen to be com-
pletely and brilliantly developed, and on the whole the evidence
derived from a cyanogen flame appears to strengthen tlie view which
associates the Swan spectrum with the production of carbon monoxide.

Keviewing the evidence which has been oifered,it appears that the
primary source of light in flames is to be found in the intense vibra-
tory motion which is determined by the act of chemical union. This
is seen in the phosphorescence of phosphorus, in the flame of hydrogen,
and at the base of the flames of the hydrides of silicon and carbon.
A secondary source of light arises when the temperature effect of
the primary combustion causes the glow of a product or partial
product of combustion. This is seen in the white flame of phos-
phorus, in the brightest part of the flame of silicon hydride, and
in the bright yellow-white part of ordinary hydrocarbon flames.

The question of the luminosity of flames containing the vapours
of salts introduces new problems, the elucidation of which is far from
beiug complete. This question, however, cannot be considered on
the present occasion. FA S 1

Smithells and Dent, Journ. Chen). Soc. 65, p. 603 (1894).

1897.] Greek and Latin Palaeography. 375

WEEKLY EVENING MEETING,
Friday, March 19, 1897.

Basil Woodd Smith, Esq. F.R.A.S. F.S.A. Vice-President,
in tlie Chair.

Sir Edward Maunde Thompson, K.C.B. D.C.L. LL.D. F.S.A.
(Principal Librarian of the British Museum).

Greeh and Latin Palseography,

Our knowledge of Greek and Latin Palaeography has expanded so
largely during the last quarter of a century, that, in response to an
invitation to read a paper before the Eoyal Institution, I have
ventured to select it as the subject for the discourse this eveuinc^.
For, although palseography is a science which is, in the nature of
things, confined to the enquiries of comparatively few students, yet
that branch of it which deals with writings in Greek and Latin may
appeal to the interest of most of us, whose education has been
founded on the study of the classical authors of Greece and Eome.
And, further, the derivation of the alphabet now in use throughout
the greater part of the world, immediately from the ali^habet of the
Latins and more remotely from that of Hellas, and the various
changes through which it passed before attaining a simple and
regular form, are matters for the curiosity, if not for the study, of all
who claim to take an interest in the history of literature.

The extension of the knowledge of our subject during recent
years is due in the highest degree to the invention of photography,
and to the perfection to which the art of photographic reproduction
has been brought. When we regard the rude and inexact facsimiles
from manuscripts, which appear in the older works on palaeography,
we cannot conceive the possibility of the student learning anything
of value from them. For all scientific purposes they are worthless,
and they could only serve to convey a very general idea of the
character in which the originals were written. Next came works
executed with more skill, but so costly that they were beyond the
reach of all but the wealthy ; and, again, careful and exact as they
are, they fail to reproduce those minute variations and delicate
nuances of the manuscript, which it is impossible for a second hand
to render faithfully. Photography came and made the path smooth.
Under ordinary conditions it gives us a facsimile of the original,
which, next to being the original itself, is the best that we can
desire. The agency of the second hand, which involuntarily but

2 0 2

376 Sir Edward Maunde Thompson [March 19,

inevitably imported its own character into the old hand-made
facsimile, is dispensed with ; the agency of light can never alter
the character of the first hand. The collections of photographic
facsimiles issued during the last five-and-twenty years form a
palaBographical corpus which renders the study a comparatively
easy one; and, further, we now have the immense advantage of
being in a position to compare side by side, through the medium of
those trustworthy facsimiles, texts which are in reality scattered
through the libraries of Europe. Five-and-twenty years ago the
palaeographer working in the public library of his own country
might have a good knowledge of the handwritings of the later
middle ages ; the material under his hands was sufficient ; but of
the earlier periods his experience was limited, and he could scarcely
speak without hesitation on questions of the palaeography of manu-
scripts, of which his library contained only a few examples. We are
in a very different position to-day. The abundant supply of fac-
similes has given us the meaus of training the eye and of familiarising
it with the handwritings of all periods.

And while our material has thus been concentrated by photo-
graphy, it has also actually increased in amount. Kecent excavations
in Egypt have placed us in possession of documents which, for the
first time, have brought us almost in touch with the classical period
of Greek literature. Greek writing of the third century before
Christ was scarcely known to us before these modern discoveries ;
we now know that at that age writing was a common and widespread
accomplishment under the Ptolemies in Egypt. Nor in this direction
alone have we profited : the numerous papyri which have been and
are being found of the early centuries of the Christian era supply the
links, formerly wanting, to trace the descent of the uncial writing of
the earliest extant Biblical codices of the fourth and fifth centuries
from the earlier examples. The chain is now nearly complete, and
the history of Greek handwriting can be followed with more or
less precision through a period of some seventeen centuries before it
became fixed by the printing press. The additions to our material
for Latin palaeography have not been so abundant, but they have
been scarcely less interesting. Excavations on the site of Pompeii
and in other places have given us an insight into the character of
the handwriting of the Eoman people in the early time of the empire ;
and^ even if no great classical work has been recovered, we have in
the wall scribblings that have been laid bare, and in the waxen
tablets that have been found, invaluable examples of the writing of
everyday life and of the business transactions of the people.

The connection between the Greek and Latin alphabets is obvious
when we compare their early forms. The primitive Greek alphabet
of two-and-twenty signs borrowed from the Phoenicians — written at
first from right to left, and eventually from left to right, after
passing through that curious period of boustrophedon writing, in which
a line written from the right was succeeded by one written from the

1897.] on Greek and Latin Palaeography. 377

left, and so on, just as the ploughing ox cuts the furrows in the field —
this primitive alphabet, under local influences which cannot now be
defined, developed into two main branches or groups, to which the
designations of Eastern and Western have been applied. The Eastern
or Ionian branch was that current in Asia Minor and the neighbouring
islands, and in certain states of Greece ; the Western branch was
employed more extensively in Greece and in most of the states of the
Peloponnese, and also in the Achaean and Chalcidian colonies of
Italy and Sicily. The most special mark of distinction between the
two branches is the symbol or letter representing the sound x. In
the Eastern branch this sound is represented by H, and the letters
X and ^ have the sounds of kh and ps, as we know them in ordinary
usage in Greek literature, Athens having naturally followed the
Ionian system. In the Western branch the letter H is wanting, while
X and ^ have the values of x and kh ; the sound ps being expressed
in separate letters tt? or ^s, or rarely by a special sign '^. No satis-
factory explanation has yet been found for this remarkable distinction
The Latins borrowed the Western Greek alj)habet from the Chalcidian
colonies, such as Cumae, planted on the Campanian coast. The Greek
double letters (or aspirates) tli, ph, kh, representing no sounds in the
Latin tongue, were dropped ; the third letter, at first used to express
the hard g sound, came to be also used for the k sound, and the letter
K, though it remained in the alphabet, became almost a dead letter.
Gradually the k sound ousted the g sound in the third letter, and for
expression of the latter another symbol had to be invented. This was
found by differentiating the C by a stroke or tail, thus creating the
letter G. A place for this new letter had been meanwhile left vacant
by the gradual extinction of the soft s ov z sound in Latin, whereby
the presence of Z was dispensed with. In Quintilian's time X was
*• ultima nostrarum " and closed the alphabet. Later, Y and Z were
added, not for the purpose of expressing native sounds, but for the
more exact transliteration of Greek.

To find illustrations of the use of the early forms of the Greek and
Latin alphabets, we should have recourse to inscriptions on stone or
metal, but this would take us beyond the limits of our present subject,
which is confined to the history of the development of handwriting, as
distinct from epigraphy. And yet, while we thus lay aside the more
ancient examples of texts, either Greek or Latin, we must not assume
that handwriting only began where the early inscriptions leave ofiF.
In consequence of the recent discoveries in Egypt, our former views
in regard to the antiquity of the practice of writing in Greece
have undergone considerable modification. There is always, and I
imagine there always has been, a tendency to refuse to bygone
generations that capacity for acquiring and diffusing knowledge
which we flatter ourselves is an attribute of modern intelligence ;
and all unexplored periods of history are dark ages. But we now
know that three hundred years before the Christian era the Greeks in
Egypt, in difierent classes of society, the professional man and man

378 Sir Edward Maunde Thompson [March 1^,

of business, jnst as well as the literary man, could write with as
much ease and fluency as we can ourselves. Their handwriting is
fully matured and bears on its face the evidence of a development
which must have been the growth of a long period. The knowledge
of writing in (Greece, we fully believe, must be at least coeval with
the oldest Greek inscriptions ; and we are not to assume that, because
those inscriptions are laboured and painfully executed, therefore the
handwriting of the same time was equally laboured and painful. On
the contrary, the handwriting may have been, and probably was^
tolerably fluent ; and it would be jas unjust to measure the ancient
Greek's capacity for expressing himself with the pen by the standard
of his inscriptions, as it would be to take the rustic lettering of our
provincial tombstones as a measure for deciding the proficiency of
modern penmanship.

As I have already said, we have to depend, for our acquaintance
with the earliest examples of Greek writing, upon the papyri which
have been found in Egypt. These may be broadly classified in two
divisions : the first, literary ; the second, official and domestic. The
literary documents, naturally, are generally written with more care
than those of the other class. Texts intended for the market were
inscribed in a formal style which would correspond to the print-
ing of the present day. But others, even though of a literary
character, if written for the scholar's own use, would not be neces-
sarily transcribed in this formal fashion, but might appear in the
ordinary current handwriting of the scholar himself or of his
amanuensis. On the other Land, official and domestic documents
are generally written in cursive handwritings, more or less exact or
careless, according to the education or skill of the writer. In dating
the domestic documents we have not the same difficulty — as a rule —
as in dealing with literary works, for a large proportion bear actual
dates, and thus form standards of comparison for those documents
which have not been so dated. In dealing with literary works
written in the cursive handwritings we have the same advajitage of
comparison with the dated cursive examples of the official and
domestic division. But, when we come to the formally written works,
our real difficulty begins.

The faculty of deciding the age of handwritings of a formal
character of any period must chiefly grow from familiarity j and this
familiarity, of course, can only be acquired by the survey of a large
number of examples. Every palaeographer knows how easy it is to
assign dates to manuscripts of the middle ages, say from the twelfth
to the fifteenth centuries, of which there are plentiful examples ; his
difficulties begin when he moves back into the earlier centuries
when his material is more limited ; and when he comes to examine,
for example, such a formal handwriting as the uncials of the fourth,
fifth and sixth centuries, he does not venture to be dogmatic. "Wheii
we go back to a period still more remote, such as the third, second
and first centuries B.C., our difficulties become extreme. It is not to

1897.] on Greek and Latin Palseography. 379

be wondered at, then, that the dates formerly assigned to some of
the examples of classical papyri must be reconsidered by the light of
recent discoveries.

If we take up a table of alphabets, drawn from the oldest ex-
amples of Greek writing extant, and glance along the lines of the
different letters, we see how various their formation was under
different conditions, even at that early period.* In the first two
columns we have the formal letters used in the classical fragments ;
in the others we have the letters used in documents, all of a more or
less cursive character. How very cursive some of them could become
is evident, if we examine the examples of the letters Lambda, Mu,
Nu, Pi, Tau and Omega. With regard to the last letter, the transi-
tion, which without those examples it would not be easy to exjolain,
from the original horseshoe-shaped letter to the later w form is
readily followed. How easily there might have been a confusion
between a Lambda and a Mu and a Pi ! for each of those letters in
some instances is formed simply by a curved stroke. The Tau with
the horizontal only on the left is an example of a rapid method of
constructing the letter, which has a modern parallel in the t of some-
what similar shape in use among the French. A second table will
carry us on to the third century after Christ, missing, however, one
century, the first century B.C. ; for it is a remarkable circumstance
that among the large number of papyri that have been recovered
there are scarcely any that actually bear dates within that hundred
years. However, comparing the forms of letters of the second cen-
tury B.C. with those of the first century of our era, we conclude that
it was a period of decadence in Greek handwriting, the letters of the
later century being inferior to those of the earlier time.

Probably the very oldest example of Greek writiug is the papyrus
fragment, now in the Imperial Library at Vienna, inscribed with an
invocation of a certain Artemisia against the father of her child. It
is probably as early as the first half of the third century b.c. The
handwriting is rough, every letter being written separately in the style
of an inscription ; and, judging by the fluent character of other extant
specimens of nearly contemporary current handwriting, we are justi-
fied in assuming this papyrus to represent, not the educated style of
tie time, but rather the imperfect effort of one not much accustomed
to use the pen.j

It is, however, even though an illiterate production, a document
of much value in that it shows exactly individual forms of letters of
the formal alphabet of the time. The contemporary literary hand
is seen at its best in some fragments of the ' Phaedo* of Plato, which
had been employed, together with other papyrus documents, as the

* See the carefully drawn table in 'The Flinders Petrie Papyri,' ed. Prof. J. P.
Mahnify ; in the ' Cunningham Memoirs ' of the Eoyal Irish Academy, 1891.
t Facsimiles of the Paheograpliioal Society, ii. 14L

380 Sir Edward Maunde Thompson [Marcli 19,

material for cartonnage mummy-cases in the Greek colony of Gurob
in the Fayum. The official deeds found among these fragments date
from about the year 260 B.C. ; this manuscript of Plato may therefore
be placed rather earlier, for it is not probable that a literary work
such as this would have been destroyed immediately after it had been
written, although ordinary documents would cease to have any value
after a few years. It is to be regretted that what remains of this
once beautiful manuscript is in such a fragmentary condition ; but
there is still enough to show that a very perfect style of hand-
writing was employed in the production of classical works intended
for the book market in the third century B.C. The chief charac-
teristic of the writing is the great breadth — almost flatness — of
many of the letters, as compared with their height.*

The same invaluable Gurob collection of papyri also provides
us with material for ascertaining the capabilities of persons in dijBfer-
ent ranks of life to express themselves in writing — not in the formal
literary hand of the ' Phaedo,' but in the ordinary running hand of
the day. A beautiful document of the middle of the century, written
in a particularly clear and well- shaped character, is the letter of a
young man, well educated, named Polykrates, who addresses his
father with affectionate frankness, and invites him to come and stimu-
late the writer to ^hake off his present idleness ; but assures him also
that in money matters his son is quite solvent. Another letter,
equally well written, is addressed in the year 242 B.C., by one Horos,
an official, to a colleague named Armais, and seems to be prompted by
professional jealousy at his correspondent making a good thing by
the sale of oil at a price higher than that fixed by royal decree.
The writing is an excellent examjDle of that fine linked hand which
appears to have come into vogue at this time and which is so particu-
larly characteristic of the best written cursive documents of the next
hundred years. A third letter of the same time shows how a man of
the agricultural class could handle his pen. It is a communication
from a farm bailiff to his master, telling hira of the vineyard, the
olive-yard, and the dearth of water. The writing is the rough hand
of a practical man, not highly educated, but with knowledge enough
to express himself in a business-like way. In this example there is
none of the beautiful linking together of the letters which appeared
in the practised hand of the official's epistle ; here, every letter stands
apart, and perhaps we may style the bailiffs handwriting as rather of
the pothook order.

In the third century, then, before Christ we have evidence that the
Greeks in Egypt practised the two styles of handwriting : the literary
and the cursive. And the possession of a literary hand implied a
long course of practice. Like all things, handwriting is subject to
the regular laws of nature. It developes, reaches perfection, and then
decays. And it is when in the stage of perfection, that a style of

* Mahaffy, ' Flinders Petrie Papyri.'

1897.] on Greek and Latin Palaeography. 381

handwriting is adopted for a literary hand. Hence as a literary hand
it seems to burst upon us in full life : Athene springs ready armed
from the head of Zeus. But it has been previously passing through a
long period of preparation and development, the evidences of which
are lost ; and it is only because it succeeds in reaching perfection,
that it is then employed as a literary hand. When once in that posi-
tion, it may maintain its excellence for a time, but not for a loner
time. It gradually becomes a formal hand, and then an artificial
hand, and, as such, is doomed to deterioration. Meanwhile, the
natural cursive hand continues its course, and again developes a new
style, which in turn reaches perfection and then supersedes the old
literary hand, which has by this time lost all life and has become a
mere imitative script. And thus the process goes on repeating itself.
The best illustration of this law of change is to be seen in the general
adoption, both for Greek and for Latin manuscripts, of the minuscule
or small hand, as the literary hand, in place of the uncial or large
hand, early in the ninth century. The creation of minuscule writing
is naturally a long process. The large letters have to be ground
down by a long course of cursive writing, and the small letters thus
formed have to take shape and be cast in an artistic mould before
they can aspire to be used in the production of literary manuscripts.
But in the end, because they can be more fluently formed, and thus
become the more natural means of the expression of thought, they
cannot fail to supersede the older and more slowly written uncials.

The time at our disposal this evening will not allow me to take
you down to the moment of this great change. I propose to limit
my further remarks on Greek palaeography to the early centuries, and
only to touch the boundary of the mediaeval period.

To illustrate the handwriting of the first half of the second
century B.C., we may turn to two literary documents, the one written
in a cursive hand, the other in a formal hand. The first is an astro-
nomical treatise, now in Paris, which must be earlier than the year
164 B.C., as some documents of that date are written on the back of
the papyrus. The hand is of a good bold character, the prominent
feature being the linking together of the letters by connecting strokes
which has been already referred to. This papyrus was no doubt a
copy made for a scholar's own use, and not for sale. It is copied in
the ordinary character which he would write naturally. The second
papyrus, containing a dialectical treatise, of the same age, is inscribed
in the formal literary hand by a professional writer, working for the
book market. Comparing these two works with those of the preced-
ing century we should pronounce a deterioration in the formal hand,
being a style which naturally tends to become artificial ; but we do
not perceive any great change in the cursive hand, which is the
natural hand, except that it may be rather more fluent than that of
the previous century.*

* ' Notices et Extraits des MSS. de la Bibl. Imperiale,' xviii. pt. 2.

382 Sir Edivard Maunde Thompson [March 19,

We now turn the century and glance at one or two of the classical
papyri representing the first century b.o. The literary hand assumes
in some of these a more compact style. The manuscript of the 18th
book of the Iliad, known as the Harris Homer, now in the British
Museum, is an excellent specimen, but rather discoloured. Here the
writing is again of the formal literary type, the letters delicately
shaped and slightly inclining to the left. Somewhat of the same cast
of hand and of the same period is the quite recently discovered
papyrus of the odes of the poet Bacchylides. The writing is beauti-
fully clear, and, had the roll not been unfortunately broken up and a
portion of it reduced to a confusion of small fragments, the editing of
the book would not have presented most of the difficulties which now
have to be encountered.

Towards the end of the first century a more ornamental class of
writing for literary purposes appears to Lave been coming into vogue.
It was essentially a calligraphic style, and in the rounded shapes of
the letters we see an indication of the form that Greek literary writing
was to assume when the writing material changed from the frail
papyrus, on which the strokes were necessarily of a light character,
to the substantial vellum which would bear the impress of a firmer
hand. A fragment of the Odyssey, now in the British Museum, which
may be dated in the closing years of the century, is in this style.
And again, the beautifully written papyrus which contains the ora-
tion of Hyperides for Lycophron and Euxenippus, and which may be
placed in the first century of our era, is another example of this precise
but rather artificial hand.

But, now and again, a scholar, perhaps too poor to buy costly
papyri, perhaps living too far away in the country, or, it may be, pre-
ferring his own transcript to the handsomer but less correct text
which he might purchase, wrote out some favourite book for his own
use. The long-lost work of Aristotle on the Constitution of Athens,
which was recovered only a few years ago, is an instance of this
jiersonal industry. Written on the back of some farm accounts of
the year 78-79 a.d., the text is in the involved and cramped cursive
hand found in documents of the end of the century. But such home-
made books were no doubt comparatively rare by the side of those
turned out by the professional literary scribe, whose writing was now
approaching nearer to the perfect round uncial hand which we find in
the earliest vellum manuscripts. The papyrus document which comes
nearest to that round hand is the Bankes Homer of the second
century.

How this hand was taught in the schools we learn from an
interesting little diptych or pair of waxen tablets belonging to a
schoolboy of about the second century.*

This copy-book, clumsily made of wood, wdth a sunken surface
coated with wax in the usual way, contains two columns of the

* Brit. Mus., Add. MS. 34,186.

1897.] on Greek and Latin PalseograpJiy. 383

multiplication table, a little exercise in words of two sjllables, and
the boy's copy of two iambic lines set by his master, who has written
them in very good uncial letters : —

croffiov Trap" avSpo? 7rpocr8€)(ov (Tvixf^ovXiav,
fjLT] iradiv eiKT] tols <^tXots Trto-reuerat.

The poor boy knew very little Greek and was certainly not a good
writer. The master has written the sigma of a-o^jiov rather lightly,
probably the wax was too thin, close to the edge, for the stilus to
make a good imj)ression : and the pupil leaves it out altogether. But
we may turn the laugh against the pedagogue. The word Trtcrrci^eTat
should have been Trto-revere. The master discovered his error, but he
claps in his epsilon at the end of the wrong line.

The descent of the beautiful uncial writing of the vellum manu-
scripts from this earlier hand requires no further demonstration. The
three great codices of the Bible — the " Codex Vaticanus " of the
fourth century, tlie " Codex Sinaiticus " of the fourth or fifth century,
and the " Codex Alexandrinus " of the fifth century — are great palseo-
graphical monuments as well as all-important texts.

For our earliest specimens of Latin handwriting we have recourse
to the excavations of Pompeii, and of Herculaneum, and of Rome.
From Pompeii we have a large collection of wall inscriptions which
have been carefully collected by the Germans and published by them
in the volumes of the ' Corpus Inscriptionum Latinarum.' We have
also from the same source a very valuable set of waxen tablets which
were found a few years ago, and which have been partly published by
the Society of the Lincei of Rome. A complete edition has been long
since promised by Professor Zangemeister of Heidelberg.

The wall inscriptions of Pompeii are of two kinds : first, those
traced with a brush in large letters, generally in capital letters,
consisting chiefly of advertisements, recommendations of candidates,
announcements of public games, losses, houses to let, &c. — in fact,
just such advertisements as we may see placarded in print on our
own walls at the present day. Some few of these are of early date,
but most of them lie between the years 63 and 79 of our era, the
latter year being the date of the destruction of the city. The second
kind of the wall inscriptions is composed of scrawls, a few in
charcoal or chalk, but most of them scratched with a sharp point, that
is, graffiti : they are in cursive letters, and consist of all kinds of idle
scribbiings, quotations from the poets, reckonings, salutations, love
addresses, pasquinades and satirical remarks. Here again, a few may
be ancient, but most of them are of a period little anterior to the
destruction of Pompeii. Similar graffiti have been found at Hercu-
laneum, on the walls of the Palatine, and in other places in Rome.

The waxen tablets discovered at Pompeii are 127 in number.

384 Sir Edward Maunde Thompson [March 19,

They were found in 1875 in the house of a pawnbroker or banker
named Lucius Csecilius Jucundus. Enclosed in a box placed in a
recess above the portico, they fortunately escaped absolute destruction,
although much blackened and damaged by the heat. They comprise
two classes of documents, viz. deeds connected with auctions, and
receipts for payments of taxes. They range in date mostly from
A.D. 53 to A.D. 62, and they are generally trij^tychs, that is, tablets
formed of three boards or leaves of wood. Of the same period are
a few fragments of Latin-written papyri found among the Greek
collection recovered at Herculaneum. They are, however, very scanty.

The next important material consists of twenty-four waxen
tablets, which were recovered in the ancient mining works of
Verespatak, in Dacia, the ancient Alburnus Major, and concern
the private affairs of the miners. Twelve of them bear dates between
the years 131 and 167 of our era. These tablets were probably left
in the mines when the Eoman colony was suddenly attacked by the
barbarians; and it has been suggested that the destruction of the
place was effected in the war with the Marcomanni, a.d. 166-180.
They are published in the ' Corpus Inscriptionum Latinarum.'

Contemporary with these collections we may also count a few
documents and stray tiles and such fragments found at various
sites, which are scratched with alphabets or verses or haphazard
memoranda.

The greater part of the materials which have just been enumerated
consist of documents or fragments written in cursive handwriting,
and afford us means of tiacing pretty clearly the C(jurse which that
form of Eoman writing took in the early centuries, leading on to the
current handwriting which we find in the papyri of Italy of the early
middle ages, and forming eventually the type upon which the national
handwritings of Italy, France, and Spain were developed.

Two tables of alphabets in the ' Corpus Inscriptionum ' show
the forms of letters used in the wall inscriptions and those used in
the waxen tablets of Dacia. In the first division of the first plate, we
have the oldest forms of letters painted with a brush : in the first
row, square capitals, formed precisely ; in the second and third rows,
the more careless and quickly written alphabet, which, from its
negligent style, has been called Mustic. In the third and fourth
divisions are the cursive alj^habets of the graffiti. Eunning the eye
vertically down the several columns of the letters, we can follow
their changes and see the history of the development of certain forms
very plainly. In writing quickly, all parts of the letters which may
be dispensed with without obscuring their forms naturally fall away ;
the cross stroke of A is soon found to be a trouble, it drops into a
tag, and in many cases altogether disappears. The letter B, even in
the early stage in the second division, begins to lose the upper
bow. In the third division, the main stroke, instead of being drawn
in its proper vertical line, runs off to the line of the bow, and
then a bow is added on the left, giving the letter the appearance of a

1897.] on Greek and Latin Paloeography. 385

small d or tall a ; this development is seen pretty well completed in
the fourth division. The letter E, besides the capital form, is also
written in t^o vertical strokes, a form found in inscriptions and
which apj)ears in the old Faliscan alphabet. In the waxen tablets
this form is very generally used, no doubt because it was so very
easily written. In the letter F, again, the cross stroke gradually
drops away, and the letter is formed eventually of merely two strokes,
both of them vertical. The development of the tail of G can be traced
in the column as we descend. In the fourth division, the four
strokes of the letter M fall into a perpendicular arrangement. But
this form of the letter does not occur in the Dacian tablets ; it was
probably found confusing in a class of writing which contained so
many verticals. The letter N g )es through the same course, falling
into three vertical lines. The breaking up of the letter 0 is very
interesting : when it is formed by the double action of two curves
meeting, the second curve tends to become concave like the first, the
letter tinis assuming the form of a badly made cursive a. In the
letter P we see the gradual loss of the bow — or rather its change
from a curve to a mere oblique tag or stroke. Important changes
pass over the letter E ; first comes the opening of the bow, then the
gradual change in the direction of the stroke, which becomes a mere
waved line.

The second table of alphabets represents the forms of letters found
in the Dacian waxen tablets of the second century. Here is a still
further development of the letters of the graffiti., and in writing on
such a material as wax there would be even more temptation to get
rid of superfluities in the letters, than when writing on a plaster-
covered wall. Further, the tendency of the action of the hand
would be to write letters sloping rather to the left, the curves would
all tend to become concave, the stilus being held with its point inwards.
The princijjal difficulty in reading the writing on the waxen tablets is
caused by the linking of the letters, many of the combinations form-
ing almost monograms ; these are all collected in the lower division of
the plate. Accurate facsimiles of the wall inscriptions are collected
in the ' Corpus Inscriptionum ' and may there be studied in all their
details.

From the tables of alphabets it is seen how the cursive hand of
everyday life developes from the capital letters ; and those capital
letters are of course nothing more than the later development of the
archaic alphabet. To find the Roman literary hand, we must start
again from the capitals, but move in a diftereut direction from that
followed by the cursive writing. For public inscriptions a refined
and artistic form of letters w^as naturally soon required ; and the
creation of very perfect alphabets of capital letters, both square aud
rustic, resulted. To apply this large style to literary purposes may
appear to us a costly aud cumbersome method ; and it is certainly
remarkable that the practice of producing manuscripts in large letters,
or majuscules, should have endured so many centuries as it did. On

386 Sir Edward Maunde Thompson [March 19,

tlie other hand, we must remember that the many examples that have
survived probably owe their long life to the fact that they have been
always regarded as of special value, and have thus been carefully
kept, while ordinary copies, transcribed in the common handwriting
of the day, and probably far more numerous than the majuscule
codices, have been allowed to perish. However, extant examples
prove to us that capital writing was employed in the production of
important manuscripts, both in the square letter and in the rustic
letter. But, as the latter form could be more expeditiously written, it
was more frequently used than the square type. Again, the incon-
venience of the square type almost immediately caused another
modification ; the scribe took to rounding off the angles of the letters,
and a script which has received the name of Uncial writing was deve-
loped. From the fourth century, then, we have surviving examples
of manuscript volumes in these large letters. But the system could not
last ; the square letter seems to have soon fallen into desuetude ;
then the rustic hand gradually dies out, leaving the uncial in posses-
sion of the field, only, however, to fall eventually into a decrepit and
imitative state, and to disappear before the beautiful literary small
hand which, by the beginning of the ninth century, had at length, after
many vicissitudes, fully developed from the current forms of hand-
writing.

One or two fragments exist to show us the early practice of
writing in capital letters. A fragmentary papyrus was recovered from
the ashes of Herculaneum, inscribed with a poem on the battle of
Actium in a light style of rustic letters, which was probably in fairly
general use for literary purposes in the first half of the first century.
The words are separated from one another by a full point, as in
inscriptions; and long vowels are in many instances marked with
an accent — long I being indicated by doubling the letter in height.

Another fragment of interest is a scrap of a sheet of papyrus,
which contained a writing exercise of some young scholar in Egypt,
perhaps of the first or second century ; now in the British Museum.
A line from the second book of the -^neid was the text chosen for
this copy : —

" Non tibi TyudaricUs facies invisa LacaenaB."

The fragment shows a few imperfect repetitions of this line copied in
rustic capitals, with some slight variations from the normal shapes.
The letter D is exaggerated ; and (a matter of more interest) the
(Z-shaped B, the development of which in the cursive alphabet has
already been noticed, is employed instead of the usual capital.

But, as already said, we have to descend to the fourth century to
find examples of complete volumes in this large character. The
" Codex Palatinus " of Virgil, now in the Vatican Library, is the best
written manuscript of that time, and in the beautiful regularity
of its rustic writing resembles the sculptured inscriptions of an

181?7.] on Greek and Latin Palseograpliy. 387

earlier period. Another famous manuscript of the same time is also
a copy of Virgil, known as the " Schedas Vaticanse," interesting
from having a large series of illustrative paintings ; the writing not
quite so compact and regular. And of still greater interest is a third
Virgilian manuscript, the Laurentian Virgil of Florence, in the same
style of writing but of later date ; we can, almost with certainty,
place it in the middle of the fifth century, for it contains a note
of revision in the year 494. Ihe rustic capital writing of these
three examples is in its full strength. To see what it became in its
first decadence, we may glance at the manuscript of Prudentius at
Paris, written about the year 500, in which the character, though still
good, is artificial ; and an instance of pure imitation, as late as about
the year 800, is afibrded by the manuscript known as the Utrecht
Psalter.*

The evidence of the employment of the square capital for sump-
tuous manuscripts is more scanty. No volume in this style has
survived ; but a few leaves from different manuscripts are still in
existence. At St. Gall, in Switzerland, there are the remains of
what must have been a manuscript of immense size, for each page
contained only nineteen lines. Again, the author chosen for this
distinction is Virgil, and the manuscript may liavo been written early
in the fifth century.

The third class of majuscule writing is the uncial; and the
earliest example of it is probably to be found in the palimpsest
fragments of Cicero ' de Kepublica,' of the fourth century, in the
Vatican Library. Here again the manuscript when perfect must
have been of unusual size. The upper writing is the commentary of
St. Augustine on the Psalms, written late in the seventh century. The
fragmentary coj)y of the Gospels at Vercelli in North Italy, of the
end of the fourth century, shows the uncial hand in a perfect and
vigorous form ; and the manuscript of Livy in the Imperial Library of
Vienna is one of the best examples of the characters in the fifth
century. For the three following centuries, the uncial was destined
to be the chief literary hand of Western Europe ; but we must take
leave of it at this point to trace in outline the development of the
small or minuscule hand which was to supersede it.

We return to the early Roman cursive hand, and take up the
thread with the Dacian waxen tablets of the second century, selecting
one of them of the year ISD."]"

This tablet originally consisted of three leaves, and, counting six
pages to the tablet, we open it to t-how pages 2 and 3 of the triptych.
On these pages are inscribed, in Roman cursive writing, a deed record-
ing the purchase of a slave girl. When the two leaves were closed, a

* For facsimiles of these and other majuscule MSS., see Wattenbach and
Zangemeister, ' Exempla Codd. Lat. litteris majusculis scriptoruui,' 1876, 1879;
and tke Facaimiles of the Pal geographical Society.

t ' Corpus luscriptionum Latinarum,' iii. pt. 2.

388 Sir Edward Maunde Thompson [March 19,

string or wire was passed through them and was secured on the back
of the second leaf, that is, on page 4, by the seals of the witnesses ;
and on the same page the deed is repeated, in accordance with the
legal practice of the Eomans. Had waxen tablets been the principal
writing material of the Eoman world and continued to be so through
the middle ages, we should at this day be writing a script quite dif-
ferent from the one which we actually employ. The character of
the writing material has necessarily had at all times an important
influence on the character of the handwriting; a most notable
example being the development of the cuneiform writing in Babylonia
and Assyria, where clay was the writing material in general use. On
such a surface as moist clay the letters could be more easily formed
by punctures than by strokes ; and so it would have been with a
prevalent use of waxed surfaces. We have seen the disjointed
character that the Roman writing assumed in the tablets ; confined to
the same material it would have broken up still more, links and curves
would gradually have disappeared, and in the end the alphabet would
have consisted of a series of straight strokes and angles. But waxen
tablets did not constitute the only, or even the principal, writing
material of the Eomans ; and a connected current hand, gradually
changing from capital forms to minuscule forms, was developing on
papyrus and vellum, alongside the disjointed cursive letters of the
waxen tablets. Unfortunately scarcely any specimens of this current
hand of early date have been found — nothing more, in fact, than a few
subscriptions of witnesses ; we can only hope that some fortunate
discovery in Egypt may put us in possession of documents to supply
the links missing in the chain. Coming down, however, to the fifth
and sixth centuries we find ourselves again uj^on firm ground with the
papyrus documents of Eavenna and Naples and other places in Italy,
in which we see the cursive Eoman hand developed into a bold, rather
straggling character. As an example we may select a Eavenna deed
of the year 572, w^hich is a good typical specimen, and, to analyse it
the better, we may add a table of the forms of the letters, which fre-
quently changed their shape when in combination with others.*

To follow the history of this hand, I should have to trace its course
in the early middle ages through the national handwritings of Italy
and of the Frankish empire and of Spain, of which it was the parent.
Each of those national hands, the Lombardic, the Merovingian, and
the Visigothic, as they have been termed, succeeded also in develop-
ing a literary form of writing of its own, not inelegant, but still, even
at its best, rather intricate. In their cursive forms they became more
and more involved and illegible ; and, to the lasting advantage of
Western European handwriting, they were swept away by the new
hand which grew up in the reign of Charlemagne. It is, however,
not without interest to know that the genius of the Eoman cursive

* Pal. Soc, i. 2 ; and table of Latin cursive alphabets in my * Handbook of
Greek and Latin Palseogvaphy.'

1897.] on Greek and Latin Palaeography. 389

haiivi still inflaencecl the legal and diplomatic hand of Europe in the
middle ages, and that even in the modera engrossing hands of our
own law courts there yet remain traces of that influence.

To find the script which, as I have said, was destined to
oust the national hands, more particularly for literary purposes,
we turn again to the early period of the majuscule writing, the
period of capitals and uncials. Bearing in mind that the natural
law of deterioration is always at work, that a literary hand
soon becomes an artificial hand, and that the natural hand is the
cursive hand of ordinary life, we shall be prepared to find, what
really took place, that cursive forms soon began to intrude among
the majuscule forms in those manuscripts which were not of the first
order ; in other words, the scribes would allow the minuscule cursive
forms which they wrote as their ordinary hand to slip in among the
more artificial literary letters. In fact, absolute purity of the script
would only be maintained in very carefully written books. Hence
arose a class of writing which has been called Half-uncial^ because it
is composed of a mixture of uncial and small letters. No doubt it
took some little time for this kind of writing to be reduced to a
system ; and we can see it in an incipient stage of development in
such technical works as law books where this incipient style may
have become traditional. In marginal notes too, the writing space
being limited, this mixed hand was often preferred to the ordinary
cursive writing, just as we write a half-printing style of letters
in the narrow margins of our books. But those stages must have
been also passed through in much earlier times than the periods of
the extant examples ; for the half-uncial hand had become a recognised
form of literary handwriting, at least by the beginning of the sixth
century. A manuscript of St. Hilary, now in the archives of St.
Peter's at Eome, is written in this character and bears a date of
revision in the year 509-510.*

Judging from extant examples, the literary half-uncial hand appears
to have been specially in favour in Southern France and Italy ; and
eventually it has had the largest career of any form of Western writing.
We can here only mention the fact that it was the hand on which the
Irish scribes of the seventh century modelled their national writing,
which became the parent of our own Anglo-Saxon character. When,
under the fostering care of Charlemagne, the school of writing in the
Abbey of Tours, presided over by the English Abbot Alcuin, was
developing the script which was to supersede the degenerate scrawls
of the national Merovingian hand, the literary half-uncial was chosen
as a model, and a beautiful form of writing, such as is seen in the
Gospels of the Emperor Lothaire of the middle of the ninth century,
was the result. This hand, somewhat simplified, became the Carlo-
vingian minuscule which was gradually adopted as the basis of the
mediasval literary hands of Western Europe. But when those new

* Pal. Soc, 1.136.
Vol. XV. (No. 91.) 2 d

390 Greek aud Latin Palaeography. [March 19,

national hands began in most countries to pass into slovenly age in
the fifteenth century, wc owe it to the sense of beauty in the Italians
that a better model than that period could afford was found for the
choicest types for the newlj invented art of printing. The Carlo-
vingian writing had passed into a beautiful form under the hands of
the Italian scribes of the eleventh and twelfth centuries ; and when,
in the Eenaissance, fastidious taste rejected contemporary writing as
not being excellent enough for the highest standard, it was to that
earlier form that men again turned as the only pattern fit for the
reproduction of manuscripts of the classics, and then for the printing
of books, in the type, so perfect in its simplicity, which we call
Eoman.

[E. M. T.]

1897.] Early Man in Scotland. 391

WEEKLY EVENING MEETING,
Friday, March 26th, 1897.

Sib James Criohton-Browne, M.D. LL.D. F.R.S. Treasurer
and Vice-President, in the Chair.

Sir William Turner, D.C.L. LL.D. F.R.S.

Early Man in Scotland.

In Scotland, as in other countries, man existed before the time of
written history. The conditions under which his remains are found,
and the works which he has left behind him, provide the data for
determining their age, not absolutely or capable of being expressed
in numbers of years, but relatively to each other.

Marked differences existed in the physical conditions of Scotland,
and indeed in the northern parts of England also, as compared with
the southern districts of England and the adjoining parts of France
and Belgium at the first appearance of primeval man in those countries .
It is the more necessary, therefore, that the conditions then prevailing
in Scotland should not be overlooked.

No evidence sufficient to satisfy geologists has been advanced to
prove that man existed in Britain during the period called Tertiary.
So far, indeed, as Scotland is concerned, evea if it were admitted that
in other parts of the globe man had been on the earth during Tertiary
times, there is little likelihood that his remains could have been pre-
served ; for in that country the Tertiary is represented chiefly by
volcanic rocks, and a few patches of sand and gravel with rolled sea
shells belonging to the closing stages of that period.

From the careful study which geologists have given to the surface
of Scotland, it is evident that at the commencement of the period
termed Quaternary or Pleistocene, immediately succeeding the Ter-
tiary, the whole of the country was covered with ice which formed a
great sheet 3000 or 4000 feet thick in the low grounds, of which
the lower boulder clay, or till, as it is termed, was the ground-
moraine.

As an upper boulder clay also occurs, which is often separated
from the lower boulder clay by stratified deposits, some of which
contained marine and other fresh water and terrestrial organic remains,
it is obvious that the Ice Age was not one uninterrupted period of con-
tinuous cold.* The lower and upper tills are the ground-moraines of

* For the evidence on which these statements are based, consult the ' Great
Ice Age,' by Professor James Geikie, edition 1894, also liis 'Classification of
European Glacial Deposits,' in Journal of Geology, vol, iii. April-May, 1895.

2 D 2

392 Sir William Turner [March 26,

independent ice sheets, each indicating a distinct epoch, separated by
an interglacial period. The earlier epoch was that of maximum
ghiciation, and the ice sheet extended over the north and middle of
England, as far south as the Thames Valley and the foot of the
Cotswold Hills, but the high moors in Derbyshire and Yorkshire and
the tops of the highest mountains in Wales and Scotland rose above
its surface. The great Mer de Glace stretched westward over Ireland
into the Atlantic, whilst on the east it was continuous across the
North Sea, with a similar ice sheet which covered Scandinavia and
the region of the Baltic, and extended south to the foot of the hiils
of central Europe, and overspread much of the great central plain.
In the extreme south of England, therefore, the conditions differed
from those that obtained in the country further north. Although not
actually covered with a sheet of ice, yet the more southern counties
had been of necessity under the influence of cold, and must have been
subjected to the effects produced by rain and snow, by freezing and
thawing.

During the succeeding intergrlacial epoch the climate eventually
became temperate and genial, and vegetable and animal life abounded.
It is to this stage that most of the Pleistocene river alluvia and
cave deposits of England and the adjacent parts of the Continent are
assigned. The British Islands appear at that time to have been
joined to the Continent, and the same mammalian fauna then occupied
Britain, France and Belgium, which implied similar climatic condi-
tions. As examples of these, it may be sufficient to name the larger
mammals, as the cave and grizzly bear, the hyaena, lion, Irish deer,
reindeer, hippopotamus, woolly rhinoceros, straight-tusked elephant
and mammoth, all of which are now either locally or wholly extinct.

Abundant evidence exists that man was contemporaneous with
these mammals in western Europe, as is shown by the presence of
his bones alongside of theirs, and of numerous works of his hands,
more especially the implements and tools which he had manufactured
and employed. To a large extent these consisted of flint, rudely
chipped and fashioned. To these implements, and to the men who
made them, the well-known term "Palaeolithic" is applied. But
along with these, other implements have been discovered, made from
the bones, horns and teeth of the larger mammals, on some of which
animal forms and incidents of the chase have been sculptured both
with taste and skill. Up to now, however, no trace of pottery which
can without question be referred to Palaeolithic men has been found,
and no habitations, except the caves and rock shelters which nature
provided lor them.

One may now consider how far northwards in Britain Palaeolithic
man and the large mammals, with which he was contemporaneous,
have been traced. The exploration of caverns made by Professor
Boyd Dawkins, and other geologists associated with him, has proved
that bones of certain of the mammals of this epoch were present
in caves in Derbyshire, Y.orkshire and North Wales, and that human

1897.] on Early Man in Scotland. 393

remains and implements of PalaGolithic type have been found along
with them in the Robin Hood cave in the Cres^swell Crags, and in
caverns in North and South Wales.

When Scotland is considered, evidence of the existence of the
mammals of this epoch is not so abundant, yet the interglacial beds
of that country have yielded remains of mammoth, reindeer, Irish
elk, urus and horse. Bat notwithstanding the keen scrutiny to
which the superficial deposits in Scotland have been subjected by
the members of the Geological Survey and others, no traces either
of the bones of Palaeolithic man or of the work of his hands have been
discovered in North Britain. This, indeed, is not much a matter of
surprise, for it must be remembered that, subsequent to the genial
interglacial epochs another ice sheet, that of the upper boulder clay,
made its appearance, grinding over the surface of the land, wearing
away alluvia, and largely obliterating the relics of interglacial times.
Hence interglacial beds occur only at intervals and are very fragmen-
tary. Nor in Scotland are there any caves similar in dimensions to
those which in England and elsewhere have yielded such abundant
traces of Palaeolithic man and his mammalian congeners. If Palaeo-
lithic man ever did exist in Scotland, and there is no reason why he
might not have migrated northward from Yorkshire and Wales, yet
one could hardly expect to discover traces of his former presence. In
Scotland there are no massive limestones, with extensive caverns, in
which man could have sheltered, and in which his relics and remains
could have been secure from destruction during the advance of the
second ice sheet. It is only in the alluvial deposits of interglacial
times that such traces have been preserved, but these deposits, as we
have seen, were ploughed out and to a great extent demolished by
the later sheet of ice. The shreds that remain, however, are of ex-
treme interest, from the fact that they contain relics of the Pleis-
tocene mammals, with which Palaeolithic man was contemporaneous ;
and there is a bare chance that some day traces of man himself
may be encountered in the same deposits.

Geologists have shown that in the regions which were overflowed
by the second or minor ice sheet no traces of Palaeolithic man, or of
the southern mammals with which he was associated, have ever been
met with in British superficial alluvia. When found in those regions
out of Scotland, they occurred in caves chiefly, and sometimes in the
stratified deposits which here and there underlie the upjDer bouldei-
clay and its accompanying gravels.

So far as Scotland is concerned, one must look for a period subse>-
quent to the melting of the second great ice sheet for evidence of the
existence of early man. After its disappearance important fluctuations
in temperature and in the relative level of land and sea took place
from time to time, so that the climate and the area of land in Scotland
diifered in some measure from what is known at the present day.
Eventually a period of cold again occurred, not so severe, undoubtedly,
as in the two preceding glacial epochs, but sufficient to bring into

394 Sir William Turner [March 26,

existence considerable district ice sheets and extensive valley-glaciers
in the Highlands and Southern Uplands. Scotland at this stage was
partially submerged, and many of the Highland glaciers reached the
sea and gave origin to icebergs. The submergence slightly exceeded
100 feet, and the marine deposits formed at the time are charged with
arctic shells and many erratic blocks and debris of rocks. On a sub-
sequent elevation of the land, the beach formed at this level consti-
tuted a terrace, well marked on the coast line in many districts, and
now known as the 100-foot beach.

There is good reason to believe that the elevation referred to was
of sufficient extent to join Britain again to the Continent. It is to
this stage that the great timber trees which underlie the old peat
bogs of Scotland are referred. The peat with its underlying forest
bed passes out to sea, and is overlaid in the carse lands of the Tay
and the Forth by marine deposits, which form another well-marked
terrace, the 45 to 50 foot raised beach of geologists.

'^I'hus the elevation of the land that followed after the formation of
the 100-foot beach coincided with an amelioration of climate and with
the presence of an abundant vegetation, and large mammals, such
as the red-deer, the elk, and the Bos primigenius roamed through
the woods. While these conditions obtained partial submergence
again ensued, and the sea rose to 50 feet, or thereabouts, above its
present level. Within recent years it has been shown that during
this period of partial submergence glaciers reached the sea in certain
Highland firths, which would seem to show that the climate was hardly
so genial as during the preceding continental condition of the British
area, when that region was clothed with great forests. Ere long,
however, elevation once more supervened, and the sea retreated to a
lower level. Here it paused for some time, and so another well-
marked terrace was formed, that which is known as the 25 to 30 foot
beach.

There is not any evidence of the presence of man in Scotland
during the formation of the 100-foot beach or terrace, but one can
speak with certainty of his presence there during tlie period of forma-
tion of the later beaches. If one could put oneself into the position
of an observer, who at the time of the 40-50 foot submergence had
stood on the rock on which Stirling Castle is now built, instead of
the present carse lands growing abundant grass and grain, and studded
with towns, villages, and farm-houses, one would have seen a great
arm of the sea extending almost if not quite across the country from
east to west, and separating the land south of the Forth from that to
the north. In this sea great whales and other marine animals
disported themselves, and sought for their food. Abundant evidence,
that this was the condition at that time in the Carse of Stirling, is
furnished by the discovery during the present century of no fewer
than twelve skeletons of whalebone whales belonging to the genus
BalaBuoptera or Finner whales, imbedded in the deposit of mud, blue

1897.] on Early Man in Scotland. 395

silt and clay which formed the bed of the estuary.* This carse clay,
as it is called, is now in places from ,45 to 50 feet above the present
high-water mark, and is extensively used for the manufacture of
bricks and tiles. At a still lower level lies the carse clay uf the
25-30 foot terrace. Until the beginning of the present century the
clay had been covered by an extensive peat moss, which the pro-
prietors of the land have removed. The question which has now to
be considered is — Did man exist in Scotland at the period of the
formation of the carse clays and of the two lower sea beaches ? There
is undoubted evidence that he did.

Along the margin of the 45-50 foot terrace in the neighbourhood
of Falkirk one comes upon the shell-mounds and kitchen-middens of
Neolithic man. All these occur on or at the base of the bluffs which
overlook the carse lands — or, in other words, upon the old sea-coast.
Again, in the Carse of Gowrie, a dug-out canoe was seen at the very
base of the deposits, and immediately above the buried forest-bed of
the Tay Valley. The 25-30 foot beach has been excavated out of
the 40-50 foot terrace ; it is largely a plain of erosion rather than of
accumulation. It is probable, therefore, that many of the relics of
man and his congeners which have been obtained at certain depths in
the 25-30 foot beach may really belong to the period of the 40-50 foot
beach. Some of these finds will now be referred to.

In 1819 the bones of a great whale, estimated at about 72 feet
long, were exposed in the carse land adjoining the gate leading into
the grounds of Airthrey Cfstle, near Bridge of Allan, about 25 feet
above the level of high water of spring tides. Two pieces of stag's
horn, through one of which a hole about an inch in diameter had been
bored, were found close to the skeleton. In 1824, on the estate of
Blair Drummond, in the district of Menteith, a whale's skeleton was
exposed, and along with it a fragment of a stag's horn which was said
to have a hole in it and to have been like that found along with the
Airthrey whale. Mr. Home Drummond also states that a small piece
of wood was present in the hole, which fitted it, but on drying, shrunk
considerably. Unfortunately, these specimens have been lost, and no
drawings or more detailed descriptions were ever apparently published,
though in some geological and archeological works they have been
stated, without any authority, to have been lances or harpoons.
Twenty years ago the skeleton of another whale was exposed at
Meiklewood, Gargunnock, a few miles to the west of Stirling, and
resting upon the front of its skull was a portion of the beam of the
antler of a red deer, fashioned into an implement eleven inches long,
and six and a half inches in greatest girth ; a hole had been bored
through the beam, in which was a piece of wood one inch and three-
quarters long, apparently the remains of a handle. The implement

* See more particularly Mr. Milne Home's ' Ancient Water Lines,' Edinburgh,
1882, and ' The Raised Beaches of the Forth Valley ' by D. B. Morris, Stirling,
1892.

396 Sir William Turner [Marcb 26,

was tnr. cated at one end, and shaped so that it could have been used
as a hammer, whilst the opposite end was smooth and bevelled to a
chisel or axe- shaped edge formed by the hard external part of the
antler.* There can be no doubt that this implement resembled those
found alongside of the Airthrey and Blair Prummond whales earlier
in the century, and it effectually disposes of the statement that they
were lances or harpoons. Dug-out canoes have indeed been found
imbedded in the Carse clays at a similar level, so that the people of
that day had discovered a means of chasing the whale in the water ;
one can, however, scarcely conceive it possible to manufacture a horn
implement sufficient to penetrate the tough skin and blubber of one
of these huge animals, and to hold it in its efforts to escape. It is
much more probable that the whale had been stranded at the ebb of
the tide in the shallower water near the shore, and that the people
had descended from the neighbouring heights, and had used their
horn implements, with their chisel-like edges, to flense the carcass of
its load of flesh and blubber, and had carried the spoil to their
respective habitations. There can be little doubt that these imple-
ments rank, along with the dug-out canoes, as the oldest relics made
with human hands which have up to this time been found in Scotland,
and that they belong to the earliest period of occupation by Neolithic
man.

After the oscillations in the relative level of land and sea had
ceased, and the beach found at the present day had been formed,
evidence of the presence of Neolithic man and of mammals, both wild
and domesticated, such as now exist in Scotland, becomes greatly
multiplied.

Shallow caves or rock shelters situated in the cliff which bounds
the esplanade at Oban Bay, which, after being closed for centuries
by a landslide from the adjacent height, had recently been quarried
into in obtaining stone for building purposes, were described in the
lecture.f The caves were as a rule 100 yards inland, and about
30 feet or more above the present high- water mark. They had, no
doubt, been formed by the action of the waves at the period of forma-
tion of the 25-30 foot beach, for the floor of one of the caves was
covered by a layer of gravel and pebbles, which had been washed
there when the sea had had access to it.

In these caves, bones representing fifteen human skeletons, men,
women, and children, were found ; also bones of the Bos longifrons,
red and roe deer, pig, dog, goat, badger, and otter, shells of edible
molluscs, bones of fish and claws of crabs ; flint scrapers, hammer
stones, implements of bone and horn fashioned into the form of pins,
borers and chisel-shaped instruments. In one cave several harpoons

* I described this implement in Reports of British Association, 1889, p. 790.
It has subsequently been figured in a Report by Dr. Munro in the ' Proceedings
of the Society of Antiquaries/ 1896.

t For a detailed description, see papers by Dr. Joseph Anderson and the
Author in Proc. Scot. Soc. Antiquaries, 1895.

1897.] on Early Man in Scotland. 397

or fish spears made of the horns of deer were obtained ; similar in
form to those found in the Victoria Cave, Settle, in Kent's Cavern,
and in the grotto of La Madelaiue, France, which in some of these
instances have been associated with Palaeolithic objects.

An account was then given of the construction and contents of the
chambered horned cairns in Caithness and the north-west of Scotland,
which have been so carefully investigated and described by Dr.
Joseph Anderson.* The presence of incinerated bones and of unburnt
skeletons showed the cairns to have been places of interment, whilst
flint flakes and scrapers, bone and jjolished stone implements, and
shallow vessels of coarse clay, associated them with Neolithic man,
obviously the same race as the builders of the English long barrows.

Stone abounds in Scotland, and the polished stone implements,
which have been found in every county, in the soil and near the
surface of the ground, are often of large size and beautifully ground
and polished. Flint, ou the other hand, is confined to a few localities,
as the island of Mull and limited areas in the counties of Banff and
Aberdeen. The nodules are as a rule small in size, and though
adapted for the manufacture of arrow-heads and scrapers, flint does
not seem to have attained the same importance in Scotland as the raw
material provided by nature for the manufacture of articles used by
Neolithic man, as was the case in England and Ireland.

Although there is ample evidence of the nature of the implements
and weapons manufactured by Neolithic man, and of his methods of
interment in rock shelters and chambered cairns, no traces of built
dwellings which can be ascribed to the people of this period have
been discovered. Doubtless their habitations were constructed of
loose stones and turf, and sun-dried clay, or of the skins of animals
killed in the chase spread over the branches of trees, which, from
their fragile and destructible character, have not been preserved.

In the course of time stone and bone, readily procurable, and which
are directly provided by nature for the use of man, gave place to
materials which required for their manufacture considerable skill and
knowledge. The introduction of bronze as a substance out of which
useful articles could be made, marked an important step in human
development, and could only take place after men had learnt by
observation the ores of copper and tin, and by experiment the methods
of extracting the metals from them, and the proportions in which
they should be combined in the alloy in order to secure the necessary
hardness. So far as Scotland is concerned, bronze must have been
introduced from without ; its manufacture could not have been of
indigenous development, as the ores of tin and copper do not occur
in North Britain. Doubtless it came from the southern part of our
island, and was extensively employed in South Britain long before it
became substituted in the north for the more primitive materials.

There is abundant iuformation that Scotland had a Bronze Age.

♦ ' Scotland iu Pagan Times,' Ediuburgb, 1886.

398 Sir William Turner [March 26,

Swords, spears, bucklers, bracelets, rings, fish hooks, axes, chisels,
sickles and other implements made of this metal have been found in con-
siderable numbers. These objects occur sometimes singly, at others
in collections or hoards in peat mosses, or even at the bottom of lochs
and rivers, or buried in the soil as if they had been placed there with
a view to concealment, and then, through the death or removal of
their owners, had been lost sight of. In many instances these weapons
and implements are elegant in design, show great mechanical ability
in their construction, and are ornamented with much taste and skill.
Instances also are not uncommon in which objects of bronze are found
in the sepulchres of the period.

In the study of the Bronze Age in Scotland a want is experienced
similar to that felt in a review of the Neolithic period. There are no
buildings which can be distinctly regarded as dwelling-places for the
men of this time. With them, however, as in the polished Stone Age,
there is evidence of the mode in which they disposed of their dead
friends and relatives. Interments which there are good grounds for
associating with these people, have been exposed in the formation of
roads and railways, and in agricultural operations. Where the sur-
face of the ground has not been cultivated or otherwise disturbed,
in almost every county tumuli, mounds, hillocks and cairns occur,
the exploration of which has in many cases yielded interesting results.
In no instance, however, have chambered cairns, divided into compart-
ments, and possessing an entrance passage, been found associated with
articles made of bronze. The sepulchral arrangements of the period
possessed a greater simplicity than is shown in the chambered
cairu.

The interments in the Bronze Age were sometimes that of a single
individual in a knoll or mound, or under a cairn artificially con-
structed, and now overgrown with grass, heather and whin bushes, or,
as is not uncommon, in the collection of sand or gravel near the sea
shore, or on a river bank, or in the moraine of some long-vanished
glacier. At other times, in similar localities, two to six interments
had been made as if in a family burying ground. At others the inter-
ments were much more numerous, and represented doubtless the
cemetery of a tribe or clan ; one of the best known of these was
observed some years ago at Law Park, near St. Andrews, in which
about twenty interments were recognised. In another at Alloa,
twenty-two separate interments were exj^osed. Quite recently, im-
mediately to the east of Edinburgh, in the districts now known as
Inveresk and Musselburgh, not less than fifty interments of this
period have been brought to light, in connection with building
operations, which implies that theu, as now, this part of the country
was settled and had a considerable population.

Two very distinct types of interment prevailed, viz. Cremation,
with, or without cinerary urns ; and Inhumation, the unburnt body
being enclosed in a stone cist or coffin. From an analysis of 144
localities in Scotland of burials \\hich may be associated with the

1897.] on Early Man in Scotland. 399

Bronze Age,* and which included about 400 distinct interments, it
would appear that in fifty-one of these localities the bodies had all
been cremated ; in sixty they had been buried in stone cists ; in
fifteen the same mound or cemetery furnished examples of both kinds
of sepulchre, and in the rest the kind of interment was not precisely
recorded. These diversities did not express tribal differences, but
seemed to have prevailed generally throughout Scotland. Both cre-
mation and inhumation are found in counties so remote from each
other as Sutherland in the north and "Wigtown in the south, in Fife
and the Lothians on the east, and in Argyll and the distant Hebrides
in the west, as well as in the intermediate districts.

The cremation had been effected by wood fires, for in many
localities charcoal has been found in considerable quantity at the
place of interment. The heat generated was sufficient to reduce the
body to ashes, and to burn the organic matter out of the bones, which
fell into greyish-white fragments, often curiously cracked and con-
torted, which were not very friable. They were then collected and
usually placed in an urn of a form and size which we now call cinerary.
When a bank of sand or gravel was convenient, a hole three or four
feet deep was made and the urn lodged in it. Sometimes the urn
stood erect and a flat stone was placed across the mouth before the
hole was filled in with sand and earth ; at others a bed of compacted
earth, or of small stones, or of a flat stone, was made at the bottom
of the hole, and the urn, with its contents, was inverted. In some
cases the urn was protected by loose stones arranged around it. In
obviously exceptional instances, it may be perhaps of a tribal chief-
tain, a small stone cist was built to enclose the urn, and even a cairn
of stones was piled above and around to protect it and to mark the
spot.

Cremated interments not contained in urns have been recorded in
a few instances, and in them the surrounding sand or gravel has
usually been discoloured from the blackened remains and charcoal
having to some extent become diffused through it.

The largest examples of cinerary urns were from 12 to 16 inches
in height, wdth a flat narrow bottom, and 10 to 12 inches wide
at the mouth. About one-third the distance below the month the
urn swelled out to its widest diameter, and w^as surrounded by one
or two mouldings, between which and the mouth the outer surface
was often decorated with lines which ran horizontally, or vertically,
or obliquely ; sometimes they intersected and formed a chevron or a
diamond-shaped pattern. Below the mouldings, the surface was
without pattern, though sometimes raised into an additional simple
circular moulding.

When the inhumation of an unburnt body was decided on, a rude

* Most of these are recorded in the ' Archaeologica Scotica,' the ' Proceedings of
the JScottish Society of Antiquaries,' and Dr. Joseph Anderson's ' Scotland in Pagan
Times ' ; whilst others, in the author's note books, have not yet been published.

400 Sir William Turner [March 26,

cist or coffin, formed of undressed flattened stones, was built for its
reception. As a rule the sides and ends of the cist were formed each
of a single slab of sandstone, schist, gneiss, granite or other stones
ju'ovided by the rock in the neighbourhood ; but in some instances of
a stone of a different character from the adjoining rocks, and
obviously brought from a distance. The stones were set on edge and
supported a great slab, which being laid horizontally formed the lid
or cover of the cist, and which was much thicker and heavier than
the side and end stones ; sometimes, as if for additional protection, a
second massive slab was placed on the top of the proper cover. The
floor of the cist was formed, when the earth was shallow, of the native
rock, and at other times of compacted earth, or a layer of pebbles, or
of flat stones. Usually the stone walls and the cover of the cist were
simply in apposition, but sometimes they were cemented together with
clay. In some cists exposed a few years ago on the farm of Cousland,
near Dalkeith, the peculiarity was observed of the cist being divided
in its long direction into two by a stone slab down the middle.

The cists were oblong, the length exceeding the breadth, and
although they varied in size, those for adults being larger than for
children, they were always shorter than would have been required for
a body to be extended at full length. As the end stones were usually
set within the extremities of the side stones, the internal measurement
of length was some inches less than the external. The average dimen-
sions may be given for the interior about 4 feet in length, 2 feet in
breadth and 2 feet in depth. The cover slab was much larger both
in length and breadth, as it overlapped both the sides and ends.

Tliese cists remind one in their general form and plan, but on a
much smaller scale, both as regards the size of the enclosed space and
the magnitude of the stones, of the dolmens so frequent in Brittany.
As survivals in modern times we may point to the empty stone boxes,
on the cover stone of which an inscription is incised, to be seen in so
many country churchyards, built on the ground superficial to the pit
in which the body in its wooden coffin has been inhumed.

Owing to the shortness of the cist the body could not be extended
at full length, but was laid upon its side, with the elbows bent, so that
the hands were close to the face ; the hips and knee joints were also
bent so that the knees were in front of the body.

Usually only a single skeleton has been found in a cist, either a
man or a woman as the case may be. Sometimes two skeletons have
been seen, at times a man's and a woman's, doubtless husband and wife ;
in others the second skeleton has been that of a child. Sometimes the
cist was below the average in size, and contained only the skeleton of
a child or young person. Such examples throw light upon the
family I'elations of the people of this period. They show that they
desired to preserve tlie associations of kinsfolk even after death ; and
when the cist contained the remains only of a child it was constructed
with the same care as if it had been the tomb of a chief.

When cremated bodies are found associated with stone cists in the

1897.] on Early Man in Scotland. 401

same cemetery, the cinerary iirns in which the ashes were customarily
deposited lie outside the cists, and in quite independent excavations
in the soil, but in such close proximity as to show that they belonged
to the same period. In two instances short cists have been opened, in
which, alongside of the skeleton of an unburnt body were cremated
human bones, not contained in a cinerary urn, but scattered on the
floor of the cist, which conclusively prove that both cremation and
inhumation were sometimes in practice at the same interment.

One may now inquire into the reason why cinerary urns, with
their contained ashes, and short cists, enclosing bodies which had been
buried in a bent or stooping attitude, should be associated with the men
of the Bronze Age. The first and most important is the presence of
objects made of bronze. In the 144 localities under analysis in which
interments ascribed to the Bronze Age have been examined, bronze
articles were found in 34 directly associated with the interments. In
four of these the bronze was along with objects made of gold. In
seven other interments of the same character gold ornaments without
bronze were presont. The men of this period were, therefore, workers
in gold also, and as it has been, and indeed still can be, mined in
Scotland, it is not unlikely that the ornaments had been wrought
from native metal. Additional proof that the burials in short cists,
and after cremation in cinerary urns, both belonged to the same
period, and were practised by the same people, is furnished by the
presence of articles of bronze and gold in both groups of interment.

But, in addition to metallic objects, the graves sometimes con-
tained other implements and ornaments. In many localities articles
made of flint, stone, or bone and jet beads were associated with bronze.
In others flints in the form of chips, knives, arrow heads and spear
heads ; stone implements in the form of whetstones and hammers ;
bone and jet ornaments and bone pins were found in short cists, and
some of these articles also in cremation interments, unaccompanied
by bronze.

Attention has been called by Dr. Joseph Anderson to the character
of the bronze objects usually associated with these burials.* For the
most part they have been thin blades, leaf-like or triangular in form,
and either with or without a tang for the attachment of a handle.
From their shape they might have been used as spear-heads, daggers,
or knives. Not unfrequently the surfaces of the blade were orna-
mented with a punctated or incised pattern. Sometimes bronze
pins, rings, and bracelets have been obtained from these interments.
It should, however, be stated that the bronze articles and ornaments
of gold found in association with the burials are of a more simple
character, and present less variety in form, purpose and decoration
than those which have been got in hoards in various parts of Scotland.
It would seem, therefore, as if the people of this period, even if they
were in possession of such finished and beautifully decorated swords,

♦ * Scotland in Pagan Times.'

402 Sir William Turner [March 26,

bucklers, axes and bronze vessels as have been got in the hoards just
referred to, did not deposit them in the graves of their deceased
friends and relatives. It may be, however, that the simpler articles
found in the interments represent a period in the Bronze Age earlier
than that in which the art of making the more elaborate articles had
been acquired, when perhaps the custom of dejDOsiting grave goods
had been more or less departed from.

Cinerary urns are not the only utensils formed of baked clay to
which the term urn has been applied, and archaeologists recognise by
the names of " incense cups, " food vessels," and " drinking cups "
three other varieties.

The examples of so-called incense cups are not numerous in
Scotland ; they were associated with cremation interments and have
usually been contained in cinerary urns ; they are the smallest of all
the varieties of urn, and are as a rule from 2 to 3 inches high, and
about 3 inches wide. In one specimen from Genoch, Ayrshire, the
cup possessed a movable lid. Not unfrequently the outer surface was
patterned with horizontal, vertical, and zig-zag arrangements of lines.
In a few cases the sirles were perforated as if to allow the escape of
fumes, and it is probably from this character, as well as from their
small size which fitted them for being easily carried in the hand, that
they have been termed incense cups. The burning of incense would,
however, imply, on the part of the people of the Bronze Age, the
possession of fragrant gums and resins such as are not indigenous to
Britain, and which the ancient Caledonians were not at all likely to
be in a position to procure. In most instances the contents of these
cups were not preserved by the finders. An example which was dis-
covered in 1857 at Craig Dhu, North Queensferry, covered by a
larger urn, and about the size of a teacup, was filled with calcined
human bones ; the specimen from Genoch, found a number of years
ago by Dr. James Macdonald, of Ayr, contained the burned bones
and ashes of a child in its fifth or sixth year. Of the conflicting
theories as to the purpose to which these cups were applied, the
view that, like the large urns with which they were associated, they
were cinerary, and were intended for the recej)tion of the ashes of an
infant or young child, seems the most probable.

Numerous examples of the variety of urn termed " food vessel " have
been found in Scotland, and " drinking cups," although not quite so
numerous, are fairly represented. In the 144 localities under analysis
the bowl-shaped food urns were found in 31, drinking cups in 25,
and in seven instances the size and form of the urn is not stated with
sufficient precision. With a few exceptions, in which the character
of the burial had not been fully described, the urns were contained in
short cists, in which also the skeleton of an unburnt body in the bent
or contracted position, was lying. In several instances it is stated
that the urn, either food or drinking vessel, contained black dust, or
earth, or greasy matter, but burnt bones are never said to constitute
their contents. Not unfrequently, although this is not an invariable

1897.] on Early Man in Scotland, 403

rule, the urn was placed in proximity to the head and raised hands of
the skeleton.

These varieties of nrn are by no means invariably present in short
cists. In twenty-five localities where this kind of grave was seen,
there is no record of either form of urn being present. It is obvious
therefore that, though associated with so many inhumation interments,
they were not regarded as necessary accompanimeuts, and they
obviously discharged in the minds of the people of the time a different
function from that of cinerary urns. The term food-urns applied to
the bowl-shaped variety is probably appropriate, as indicating that
edible substances were placed in them, in the belief that food should
be i^rovided for the use of the corpse. It is questionable, however, if
the taller variety were drinking cups, as the unglazed clay would not
fit them for the retention of liquids for any length of time. Their
presence in the stone cists, along with, in some instances, im2)lements
and weapons, would point to the belief, in the minds of those practis-
ing this form of interment, in a resurrection of the body, and a
restoration to the wants and habits of the previous life. It may be
that placing the body in the crouching position, lying on one side,
was regarded as the attitude best fitted, when the proper time came,
to enable it to spring into the erect position and assume an active
state of existence. The practice of cremation, however, to an almost
equal extent as inhumation, by people of the same period, shows that
they may not all have shared in the belief in a corporeal resurrection.
But it should not be forgotten that, even in many cremation inter-
ments, blades and other objects made of bronze have been found along
with the burnt bones and cinerary urns, as if for use in a future life.

The association of bronze objects, both with short cists and
cinerary urns, establishes these forms of interment as practised at a
time when bronze was the characteristic metal used in many purposes
of life. The crouching attitude of the dead body, the contracted
grave, and the varieties of urns already described, are therefore to be
regarded as equally characteristic of this period, even if bronze is not
found in a particular instance associated with the interment, and this
view is generally held by archaeologists in Scotland.

In a preceding paragraph implements and weapons made of stone,
flint and bone were referred to as having been sometimes associated
with bronze, and also of similar objects having been found in graves,
in which, though obviously of the same class and period, no article
made of metal was observed. Such an association proves that there
was no sharp line of demarcation between the employment of the
more simple substances used by Neolithic man in the manufacture of
implements and weapons, and the use of bronze for similar purposes.
The two periods undoubtedly overlapped. It has been customary to
regard this overlapping as if bronze-using man had continued for a
period to employ the same substances in making useful articles as did
his Neolithic predecessors ; that time was required before the more
costly bronze, imported from foreign sources, replaced the native

404 Sir William Turner [March 26,

material, and that consequently both groups of objects became asso-
ciated in the same grave.

Additional light is thrown on the mixture of objects representing
different stages of culture in the same interment by a collection of
goods from the grave of an aboriginal Australian, buried about fifty
years ago, recently brought under my notice by Dr. E. Broom. Along
with the skeleton were found a clay pipe, an iron spoon, the remains
of a rusted pannikin, the handle of a pocket-knife, and a large
piece of flint. The handle of the knife, with its steel back, had
doubtless been used along with the flint for the purpose of obtaining
fire, as in Neolithic times a similar office was discharged by flint and
a nodule of pyrites. These accompaniments of the Australian inter-
ments show that men in a lower grade of culture and intellectual
power utilise, as opportunity offers, objects representing a much
higher civilisation. It is possible, therefore, that some of the mixed
interments ascribed to the Bronze Age may be the graves of Neolithic
men who, in conjunction with articles of their own manufacture, had
employed the material introduced by a bronze-using race, with whom
they had been brought in contact, and whose usages they had more
or less imitated.

That the inhabitants of prehistoric Scotland were not a homo-
geneous people, but exhibited different types in their physical con-
figuration, so as to justify the conclusion that they were not all of the
same race, has long been accepted by archaeologists. The first
observer who made a definite statement, based on anatomical data, was
the late Sir Daniel Wilson, in his well-known ' Prehistoric Annals of
Scotland.' Whilst admitting that the material at his disposal was
scanty, he thought that he was justified in stating that the primitive
race in Scotland possessed an elongated dolichocephalic head, which
he termed boat-shaped, or kumbecephalic. This race, he said, was
succeeded by a people with shorter and wider skulls, which possessed
brachycephalic proportions. Further, he considered that both these
races preceded the intrusion of the CeltaB into Scotland. But the
evidence is by no means satisfactory that the interments from which
Wilson obtained the long kumbecephalic skulls were of an older date
than those which yielded the brachycephalic specimens. So far,
therefore, as rests upon these data, one cannot consider it as proved
that a long-headed race preceded a broad-headed race in Scotland, and
that both were antecedent to the Celtae.

Evidence from other quarters must be looked for, especially from
the extensive researches of Thurnam, Greenwell, Eolleston and other
archaBologists into prehistoric interments in England ; and by the
study of the material which has accumulated in Scotland since the
publication of Sir Daniel Wilson's ' Prehistoric Annals.'

The remains of prehistoric man in England subsequent to the
PalsBolithic Age have for the most part been found in mounds and
tumuli, some of which were very elongated in form, others more
rounded, so that they have been divided into the two groups of Long

1897.] on Early Man in Scotland. 405

and Round barrows. There is a consensus of opinion that the long
barrows were constructed by a race which inhabited England prior to
the construction of the round barrows. The long barrows are indeed
the most ancient sepulchral monuments in South Britain ; obviously
they were erected before the use of bronze or other metal became
known to the people. They belonged, therefore, to the Neolithic Age,
as is testified by the implements and weapons found in them being
formed of stone, flint, bone and horn, and by the absence of metals.
They are not widely distributed in England, but are found especially
in a few counties in the north, as Yorkshire and Westmorland, and
in the Western counties in the south. The builders of these barrows
in their interments practised both inhumation and cremation, but the
burnt bones were never found in urns.

The study of the human remains obtained from the English long
barrows by Drs. Thurnam and Eolleston proves that the crania were
distinctly dolichocephalic, and that the height was greater than the
breadth. Those measured by Dr. Thurnam gave a mean length-
breadth index 71*4, whilst Dr. Eolleston's series were 72*6.

The round barrows were constructed by a bronze-using people.
The crania obtained in them were, as a rule, brachycephalic. Of
twenty-five skulls measured by Dr. Thurnam seventeen had the
length -breadth index 80 and upwards, and in six of these the index
was 85 and upwards. Only four were dolichocephalic, whilst in
three the index ranged from 77 to 79. In the brachycephalic skulls
the height was less than the breadth.

As similar physical conditions prevailed both in England and
Scotland during the Polished Stone and Bronze periods, there is a
strong presumption that the two races had, in succession to each other,
migrated from South to North Britain. Unfortunately very few
skulls have been preserved which can with certainty be ascribed to
Neolithic man in Scotland, but those that have been examined from
Papa Westray, the cairn of Get and Oban, are dolichocephalic, and
doubtless of the same race as the builders of the English long
barrows.

Seventeen skulls from interments belonging to the Bronze period
have been examined by the author. The mean length-breadth index
of twelve was 81*4, and the highest index was 88 '6. In each skull
the height was less than the breadth. In the other five specimens
the mean index was 74 ; the majority, therefore, were brachycephalic.
In only one specimen was the jaw prognatliic ; the nose was almost
always long and narrow ; the upper border of the orbit was, as a rule,
thickened, and the height of the orbit was materially less than the
width. The capacity of the cranium in three men ranged from 1380
to 1555 c.c. ; the mean being 1462 c.c. In stature the Bronze men
were somewhat taller than Neolithic men. The thigh bones of the
Bronze Age skeletons gave a mean platymeric index 75 * 1, materially
below the average of 81*8 obtained by Dr. Hepburn from measure-
ments of the femora of modern Scots. The tibiae of the same

Vol. XV. (No. 91.) 2 b

406 Sir William Turner [March 26,

skeletons gave a mean platyknemic index 68 • 3 ; intermediate, there-
fore, between their Neolithic predecessors and the present inhabitants
of Britain. Many of the tibiae also possessed a retroverted direction
of the head of the bone; but the plane of the condylar articular
surfaces was not thereby affected, so that the backward direction of
the head exercised no adverse influence on the assumption of the
erect attitude.

Whilst in England the Bronze Age round barrows are numerous
and the burials in short cists are comparatively rare, in Scotlandthe
opposite prevails. Whilst part of Dr. Thurnam's aphorism, viz. *' long
barrows, long skulls," applies to both countries ; the remaining part,
" short barrows, short skulls," should be modified in Scotland to " short
cists, short or round skulls."

The presence of dolichocephalic skulls in the interments of the
Bronze Age shows that the Neolithic people had commingled with the
brachycephalic race. Similarly the Bronze men, though subject to
successive invasions by Romans, Angles, and Scandinavians, have
persisted as a constituent element of the people of Great Britain.
The author has found a strong brachycephalic admixture in the
crania of modern Scots, in Fife, the Lothians, Peebles and as far
north as Shetland. In 116 specimens measured, 29, i.e. one-quarter,
had a length-breadth index 80 and upwards, and in five of these
the index was more than 85.

The question has been much discussed whether the people of the
Polished Stone Age were descended from the men of the Ruder Stone
Age, or were separated from them by a distinct interval of time. The
latter view has been supported by Professor Boyd Dawkins, who con-
tends that there is a great zoological break between the fauna of the
Palaeolithic, Pleistocene period and that of the Neolithic Age, and that
the two periods are separated from each other by a revolution in
climate, geography and animal life.*

Undoubtedly many large characteristic mammals of the Palaeolithic
fauna had entirely disappeared from Britain and western Europe, but
some nine or ten species, as the otter, wolf, wild cat, wild boar, stag,
roe, urus and horse, were continued into the Neolithic period; at
which time the dog, small ox, pig, goat and perhaps the sheep, as
is shown by their osseous remains, were also naturalised in Britain.
The continuity of our island with the Continent by intermediate
land, which existed during Palaeolithic times, also became severed,
and a genial temperate climate replaced more or less arctic conditions.

Man, however, possesses a power of accommodation, and of
adapting himself to changes in his environment, such as is not
possessed by a mere animal. The locus of an animal is regulated
by the climate and the nature of the food, so that a change of climate,
which would destroy the special food on which an animal lives, would

* Cave Hunting and Journal of Anthropological Institute, vol. xxiii., Feb.
1894.

1897.] on Early 3Ian in Scotland. 407

lead to the extinction of the animal in tliat locality. Man, on the
other hand, is omnivorous, and can sustain himself alike on the flesh
of seals, whales and bears in the Arctic circle, and on the fruits
which ripen under a tropical sun. Man can produce fire to cook his
food and to protect himself from cold, and can also manufacture
clothing when necessary. Palasolithic man has left evidence that he
had the capability to improve, for the cave men were undoubtedly in
advance of the men who made the flint implements found in the river
drifts. The capacity of the few crania of Palaeolithic man which
have been preserved is quite equal to, and in some cases superior to
that of modern savages. So far as regards the implements which
he manufactured and employed, Neolithic man showed no material
advance over the Palaeolrthic cave dweller.

The association of the bones of domestic mammals, which were
not present in Palaeolithic strata, along with the remains of Neolithic
man, proves that additional species had been introduced into Western
Europe at a particular period, probably by another race which had
migrated northward and westward ; but it by no means follows that
Palaeolithic man had of necessity disappeared prior to this migration,
and that when Neolithic man reached Western Europe he found it, as
regards his own species, a desolate solitude. How then did Neolithic
man with his associated animals find his way into Britain ?

Was it whilst the land remained, which connected Britain with the
Continent in interglacial times, and along which Palaeolithic man had
travelled, or was it at some subsequent period after the formation of
intermediate arms of the sea ? If the latter, then the further question
arises, how was the transit effected ? Neolithic man, so far as is known,
had no other means of conveyance by water than was afforded by a canoe
dug out of the stem of a tree. Although such rude boats might in calm
weather serve as the means of transporting a few individuals across
a river or narrow strait from one shore to the other, they can scarcely
be regarded as fitted for an extensive migration of people ; still less
as a means of conveying their pigs, dogs, goats and oxen. Hence one
is led to the hypothesis that, after the sea had submerged the inter-
mediate land of interglacial times, there had been a subsequent
elevation so that Britain again became a part of the continent of
EurojDC. If one may use the expression, a " Neolithic land bridge " was
produced, continental relations and climate were for a time re-estab-
lished, and a free immigration of Neolithic man with his domestic
animals became possible. This may have been at the period when
an abundant forest growth in Scotland succeeded the elevation of
what is now called the 100-foot terrace. There is no evidence of the
presence of Neolithic man in Scotland until about that period.
Before this island with its surrounding and protecting " silver streak "
settled down to the present distribution of land and water, there are
ample data, as is shown by the three sea beaches at different levels seen
so distinctly on the coast of Scotland, that frequent oscillations changed
the relative positions of land and sea to each other.

2 K 2

408 Sir W. Turner on Early Man in Scotland. [Marcli 26, '97.

From the consideration of what may be called the biological data
the conclusion seems not to be justified, that because climatic changes
had led to a disappearance of certain characteristic Palseolithic
mammals, but by no means of all, therefore Palaeolithic man had
vanished along with them. When Neolithic man reached western
Europe, he in all likelihood found his Palaeolithic predecessor settled
there, and a greater or less degree of fusion took place between them.
Hence, as the present inhabitants of Britain may claim the men both
of the Neolithic and Bronze Ages as their ancestors, it is possible
that as Neolithic man migrated northward into Scotland he may have
carried with him a strain of Palaeolithic blood.

[W. T.]

1897.] Metallic Alloi/s and the Theory of Solution. 409

WEEKLY EVENING MEETING,

Friday, April 2, 1897.
George Matthey, Esq. E.R.S. Vice-President, in the Chair.

Charles T. Heycock, Esq. M.A. F.R.S.

Metallic Alloys and the Theory of Solution.

The term alloy in its technical sense is used to indicate a solid
mixture of two or more metals. The earlier investigators in this
field, such as Matthiesen, Eiche and many others, worked mainly
with solid alloys, and they endeavoured to investigate the change in
properties of the alloy, such as conductivity for heat and electricity,
malleability, ductility and the like, with successive small changes in
composition.

This method, although well adapted to bring out properties of
alloys suitable for use in the arts, has not till recently shed much
light on the real constitution of this interesting group of substances.
Chemists have neglected the subject because the ordinary processes
by which they attack problems fail them when dealing with alloys,
on account of their opacity, want of volatility and power of being
separated from one another by crystallisation. Another difficulty
arises from the fact that the resulting alloy has usually the same
colour as the metals from which it is produced, except in a few cases,
such as the rich purple alloy of gold and aluminium investigated by
Professor Eoberts-Austen, and the alloy of zinc and silver noticed
by Matthiesen and investigated by Neville and Heycock, which has
the property of taking a superficial rose tint when heated and
suddenly cooled.

During the past twelve years considerable advance has been made
in the study of alloys by investigating some of their properties whilst
in the liquid state, such as the temperature at which solidification
commences; it is convenient to term this temperature the freezing
point. Le Chatelier, Roberts-Austen, Neville, myself and others
have all worked in this way. The result of this work may be very
briefly stated as follows.

Solutions of metals in one another obey the same laws that regulate
the behaviour of solutions of such substances as sugar in water. For
example, if we take solutions of sugar of different concentrations, but
not exceeding 3 or 4 per cent., we find that within these limits the
lowering of the freezing point is nearly proportional to the con-
centration. Exactly in the same way, if we add to a quantity of
molten sodium (freezing point 97° C.) some gold, we find the gold
dissolves much in the same way that sugar dissolves in water. On

410 Mr. Charles T. Heycoch [April 2,

determining the freezing point of tlie alloy we find that it is lowered
in direct proportion to the weight of gold added, notwithstanding the
fact that pure gold by itself melts at a temperature of 1060° C. It is
remarkable that the effect of increasing the quantity of gold in the
alloy continues to depress the freezing point of the sodium, until the
alloy contains more than 20 per cent, of gold when the minimum
freezing temperature 81 '9° C (eutectic temperature) is reached. The
case of gold dissolving in sodium may be taken as a very general one,
for a large number of pairs of metals have been examined, and with
but few exceptions, such as antimony dissolved in bismuth, the effect
is almost always to produce a lowering of the freezing point of the
solvent metal. By the solvent metal we generally mean the metal
which is present in the largest quantity.

A second point in which metallic alloys resemble ordinary
solutions is in the fact that the depression of the freezing point
is inversely proportional to the molecular weight of the dissolved
substance. Thus, if we dissolve 34:2 grams (molecular weight in
grams) of cane sugar in 10 litres of water, and determine the freezing
point of the solution, it is found to be depressed a definite number of
degrees below that of pure water. But the same depression of the
freezing point is ju'oduced by the solution of 126 grams of crystallised
oxalic acid, or only 32 grams of formic acid, in 10 litres of water.*
Alloys again appear to obey the same law ; thus it is found that if
we dissolve 197 grams of gold, or 112 grams of cadmium, or 39
grams of potassium, respectively, in a constant weight of sodium, the
freezing point of the sodium will be lowered by almost the same
number of degrees in each case. Now the numbers 197, 112 and 39
are the atomic weights of the metals, and it can be shown that these
numbers are also probably the molecular weights of these elements.
Hence we conclude that metals dissolved in each other obey the
same laws as ordinary solutions.

The above facts for the behaviour of solutions of substances in
water and organic liquids have been gradually accumulated by the
work of Blagden, Eiidorff, Coppet and Eaoult, extending from about
1780 to the present time, but no general explanation of them was
brought forward until Van'tHoff advanced the remarkable theory
that a dissolved substance was in a condition somewhat analogous to
that of a gas, the solvent substance serving the part of the vessel in
which the gas is confined, but also exerting other effects.

He further gave strong reasons for believing that substances in
dilute solution obeyed the same laws that gases do — i.e. the laws
of Boyle and Charles for temperature and pressure. Several other
theories of solution, besides what may be termed the gaseous theory,

* Although water is used as a solvent by way of illustration in these cases, it
should be stated that it is by no means a suitable liquid for such experiments,
owing to the changes it brings about in the substances dissolved. In making
such experiments it is far preferable to use benzene or acetic as a solvent.

1897.] on Metallic Alloys and the Theory of Solution.

411

liave been proposed. Notwithstanding that some weighty objections
can be urged against this theory, it is remarkable that we can by aid
of it predict the numerical values for the fall of the freezing point of
different solvents produced by the solution of other substances,
provided that we know the latent heat of fusion of the solvent.

On applying the same reasoning to alloys, we find that the theory
holds good, as the table below shows.* We see from this table that

Observed Depression in the Freezing Point of a Solvent Metal, caused
BY the Addition of One Atomic per cent, of a Second Metal.

Solvent. 1

Tin.

Bismuth.

Cadmium,

Lead.

Zinc.

Depression calcu- ]

lated on theory of

Van'tHuff.

3-0° C.

2-08= C.

4-5° C.

6-5° C.

5-lloC.

Metal dissolved
Sodium ..

At. Wt.
23

2-8

2-0

4-5

1-2

Copper .. ..

63

2-9

1-2

3-6

6-3

1-5 (rise)

Silver .. ..

108

2-9

2-0

10-8 (rise)

6-6

5-15 (rise)

Platinum

195

2-1

4-5

6-4

...

Gold .. ..

197

2-9

2-1

1-6

6-4

3-4 (rise)

Bismuth

209

2-4

.•

4-5

3-0

5-1

in no cases are the observed depressions of the freezing points greater
than those calculated from the theory, but in many cases they fall
below this quantity ; this latter fact admits of explanation.

On the theory of Yan'tHoff it is necessary that when a solution
begins to freeze the pure solvent should separate out first. This
admits, in case of aqueous solutions, of simple proof, for if we take a
dilute solution of potassium permanganate and make it freeze slowly,
we find that pure colourless ice separates out on the walls of the vessel,
whilst the purple permanganate is concentrated towards the centre.
This experiment led Neville and myself to try if a similar state of
things could be shown for metallic alloys.

We have great pleasure in bringing before the Royal Institution
this evening the first announcement of the results we have obtained.
For this purpose we took two metals, gold and sodium, the former
being very opaque to X-rays, whilst the latter is very transparent to
them. A quantity of sodium was melted in a tube, and gold dissolved
in it to the extent of about ten per cent. The alloy was then allowed
to cool extremely slowly, and sections (about ^ inch thick) were cut
from different parts of the solid alloy and placed between thin plates

* For the nature of this calculation, vide Heycock & Neville, Chem. Soc.
Jour. vol. Ivii. p. 339. Also Neville, 'Science Progress,' October 1895.

412 Mr, C. T. Eeycoch on Metallic Alloys, &c. [April 2,

of aluminium to protect them from the air. These sections were then
placed on a photographic plate, enclosed in a light-tight bag, and
exposed to the action of the X-rays. On developing the plate we
found a complete picture of the inside of the alloy. Positives
obtained from these negatives are thrown upon the screen. The
sodium is seen to have crystallised out in plates, as is evident from
its transparency, whilst the opaque gold is seen to have become
concentrated in the mother liquor between these plates, where it
finally solidified along with some of the sodium.

Very similar results are produced with other pairs of metals,
such as aluminium and gold and aluminium and copper. Behrens,
Eoberts-Austen, Osmond and others have examined alloys, after
superficial etching, with high microscopic powers, and they find a
similar separation of the constituents.

We thus see that solution of metals in one another follows
extremely closely the same laws that regulate solutions with which
we are ordinarily familiar. I should like to state here that the
matter of this lecture is largely drawn from the work carried out by
Mr. Neville, F.R.S. and myself during the past six years.

[C. T. H.]

1897.] General Monthly Meeting. 413

GENERAL MONTHLY MEETING.

Monday, April 5, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

John Howard Colls, Esq.
Hugh Ernest Diamond, Esq.
Mrs. J. Dundas Grant,
Douglas Hall, Esq.
Walter Hunter, Esq.

Frederick Morell Mackenzie, Esq. M.R.C.S.
were elected Members of the Eoyal Institution.

The Special Thanks of the Members were returned for the following
Donation to the Fund for the Promotion of Experimental Research
at Low Temperatures : —

Sir William J. Farrer £50

The following Lecture Arrangements were announced : —

Tempest Anderson, M.D. B.Sc. Four Lectures on Volcanoes. (Tiie
Tyndall Lectures,) On Tuesdays, April 27, May 4, 11, 18.

Ernest Henry Starling, M.D. Three Lectures on The Heart and its
Work. On Tuesdays, May 25, June 1, 8.

Professor Dewar, M.A. LL.D. F.R.S. M.B.I. Three Lectures on Liquid
Air as an Agent op Research. On TJmrsdays, April 29, May 6, 13.

Churton Collins, Esq., M.A. Four Lecture son The French Revolution
and English Literature. On Thursdays, May 20, 27, June 3, 10.

The Rev. J. P. Mahaffy, D.D. Professor of Ancient History in the Uni-
versity of Dublin. Three Lectures on The Greek Theatre according to
Recent Discoveries. On Saturdays, May 1, 8, 15.

J. A. Fuller Maitland, Esq., M.A. F.S.A. Four Lectures on Music in
England during the Reign of Queen Victoria (with Musical Illustrations).
On Saturdays, May 22, 29, June 5, 12.

The Pkesents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FOB

The British Museum Trustees — Catalogue of the Cuneiform Tablets in the

Kowyunjik Collection. By C. Bezold. Vol. IV. 4to. 1896.
Accademia dei Lmce^, JSea?e, ^oma— Atti, Serie Quinta : Rendiconti. Classed!

Scienze Fisiche, etc. 1° Semestre, Vol. VI. Fasc. 3-5. 8vo. 1897.
Agricultural Society of England, Boyal — Journal, Third Series, Vol. Vllf. Part 1.

8vo. 1897.
American Academy of Arts and Sciences — Proceedings, Vol. XXXII. No. 1. 8vo.

1896.
American Philosophical Society — Proceedings, No. 152. 8vo. 1896.
Asiatic Society, Boyal — Catalogue of the Library of the Royal Asiatic Society.

8vo. 1893.
Journal for 1888, 1889 and 1890. 8vo.

414 General Monthly Meeting, [April 5,

Astronomical Society, Royal — Monthly Notlcas, Vol. LVEI. No. 4. 8vo. 1897.

B inkers, Institute o/— Journal, Vol XVIII. Part 8. 8vo. 1897.

Berlin, Koniglich Preussische Akademie der Wissenschaften — Sitzungsberichte,

Nos. 40-53. 8vo. 1896.
Bevan, The Rev. J. 0. M.R.T. (the Author)— An Arohseological Survey of

Her^^fordshire. Bv J. O. Bevan and others. 4to. 1896.
Boston, U.S A. Public Library —Monthly Bulletin of Books added to the Library,

Vol. II. No. 3. 8vo. 1897.
Boston Society of Natural Jf/stor^— Proceedings, Vol. XXVII. (pp. 201-241).

8vo. 1896.
British Architects, Eoyal Institute o/"— Journal, 1896-97, Nos. 9, 10. 8vo.
Camera Club — Journal for March 1897. 8vo,

Chmical Industry. Society o/— Journal, Vol. XVI. No. 2. 8vo. 1897.
Chemical Society — Journal for Jan. find Fob. 1897. 8vo.

Proceedings, No. 173. 8vo. 1897.
Civil Engineers, Institution o/— Miiuites of Proceedings, Vol. CXXVII. 8vo. 1897.
Cracovie, V Academic des Sciences — Bulletin International, 1897, No. 1. 8vo.
De Candolle, Casimir, Esq. M.R.I. — Geneve et la Socie'te' de Lecture. Par

F. De Crue (1818-96), avec portraits. 8vo. 1896.
Editors — American Journal of Science for March, 1897. 8vo.

Analyst for March, 1897. 8vo.

Anthony's Photographic Bulletin for March, 1897. 8vo.

Astrophysical Journal for March, 1897. 8vo.

Atheufeum for March, 1897. 4to.

Author for March, 1897.

Bimetallist for March, 1897.

Brewers' Journal for March, 1897. 8vo.

Chemical News for March, 1897. 4to.

Chemist and Druggist for March, 1897. 8vo.

Education for March, 1897. 8vo.

Electrical Engineer for March, 1897. fol.

Electrical Engineering for March, 1897.

Electrical Review for March, 1897. 8vo.

Engineer for March, 1897. fol.

Engineering for March, 1897. fol.

Homoeopathic Keview for March, 1897.

Horological Journal for March, 1897. 8vo.

Industries and Iron for March, 1897. fol.

Invention for March, 1897. 8vo.

Journal of Physical Chemistry, Vol. I. Nos. 6, 7. 8vo. 1897.

Journal of State Medicine for March, 1897. 8vo.

Law Journal for March, 1897. 8vo.

Machinery Market for March, 1897. 8vo.

Nature for March, 1897. 4to.

New Book List for March, 1897. 8vo.

New Church Magazine for March, 1897. Svo.

Nuovo Cimento for Feb, 1897. Svo.

Physical Eeview for March- April, 1897. 8vo.

Science Sittings for March, 1897. 8vo.

Travel for March, 1897.

Tropical Agriculturist for Feb. 1897. Svo.

Zoopldlist for March, 1897. 4to,
Edward^, F. G. Esq. (the Author)— A Communication to the Royal Institution

on " A New Theory of Matter and Force " (MS.), fol. 1897.
Electrical Engineers, Institution of — Journal, Vol. XXVI. No. 126. Svo. 1897.
Essex County Technical Laboratories, Chelmsford — Journal for Jan.-Feb. 1897.

Svo.
Florence, Biblioteca Nazionale Centrale — Bollettino, Nos. 268-270. Svo. 1897.
Forbes, Avary W. H. Esq. MA. M.R.I, (the Author)— Is Science Guilty? or,
Some of the Sins of Civilization. Svo. 1897.

1897.] General Monthly Meeting. 415

FranMin Institute — Journal for March, 1897. 8vo.

Geographical Society, Royal — Geographical Journal for March, 1897. 8vo.
Herve, M. Henri (le Dirtcteur) — Kevue de TAeronautique, seizieme annee, 1893,
livr. 4'^; septierae annee, 189i : huitieme anne'e, 1895, livr. l''^ 4to.
1893-95.
Holmes, Mrs. Basil (the Author) — The London Burial Grounds: Notes on their

History. Illustrated. 8vo. 1896.
lllinou State Laboratory of Natural History — Bulletin, Vol. V. 8vo. 1897.

Biennial Report of the Biological Experiment tstation. 8vo. 1897.
Imperial Institute — Imperial Institute Journal for March, 1897.
Johns Hopkins University — American Chemical Journal for March, 1897.
Ker, Proftssor W. P. (the Author) — Epic and Romance: Essays on Medieval

Literature. 8vo. 1897.
Linotype Company — Sell's Dict'onary of the World's Press, 1897. (British

Empire Edition.) 8vo.
London County Council Technical Education Board — London Technical Educa.-

tion Gazette for Feb. 1897. 8vo.
Manchester Geologi'^al Society —Tra.nsaciions, Vol. XXV. Part 3. 8vo. 1897.
Marcet, William, Esq. M.D, F.B.S. F.R.C.P. M.E.I, (the Author)— A Contribution
to the History of the Respiration of Man. (Croonian Lectures, 1895.) 4to.
1897.
Mensbrugge, M. G. Van der (the Author)— Sur les nombreux effets de I'elasticite
des liquides, 2 parts. 8vo. 1896.
Liste des Publications de I'Auteur. 8vo. 1896.

Sur la theorie de I'explosion d'une bulla de savon tres mince. 8vo. 1897.
Principes ge'neraux d'une nouvelle theorie oapillaire. 8vo. 1896.
De'monstiation tres simple de la cause commune de la tension superficielle et

I'e'vaporation des liquides. 8vo. 1896.
Conservat.on des Toiles peintes. 8vo.
Sur une analogie tres impoi-tante entre la constitution des solides et des liquides.

8vo. 1895.
Sur les pressions exercees par les liquides en mouvement ou en repos. 8vo.
Quelques experiences propres a faire comprendre la constitution des liquides.
8vo. 1895.
Meteorological Society, Boyal — Catalogue of an Exhibition of Meteorological

Instruments in use in 1837 and 1897. 8vo. 1897.
Microscopical Society, Royal — Journal, 1897, Part 1. 8vo.
Navy League — Navy League Journal for March, 1897. 4to.
New Zealand, Registrar-General of — The New Zealand OflScial Year-Book, 1896.

8vo. 1896.
North of England Institute of Mining and Mechanical Engineers — Annual Report.
8vo. 1896.
Transactions, Vol. XLV. Parts 4,5; Vol. XLVI. Parts 1, 2. 8vo. 1896-97.
Odontological Society of Great Britain — Transactions, Vol. XXIX. No. 5. 8vo.

1897.
Paris, Societe Frani;aise de Physique — Bulletin, No. 93. 8vo. 1897.

Seances, 1896, Fasc. 3. 8vo. 1897.
Pharmaceutical Society of Great Britain — Journal for March, 1897. 8vo.
Physical Society of London — Proceeding?', Vol. XV. Part 3. 8vo. 1897.
Radcliffe Trustees — Catalogue of Books added to the Radcliffe Library, Oxford

University Museum, during 1896. 4to. 1897.
Rome, Ministry of Public Works — Giornale del Genio Civile, 1896, Fasc. 11-12.

And Designi. fol.
Royal Society of London — Philosophical Transactions, Vol. CLXXXVII. B.
No. 140; Vol. CLXXXVIIL B. Nos. 141, 142; Vol. CLXXXIX. A.
Nos. 190, 191. 4to. 1897.
Proceedings, Nos. 367-369. 8vo. 1897.

The Year Book of the Royal Society of London, 1896-7. 8vo. 1897. (First
Issue.)
Selborne Society— '^a,ime Notes for March, 1897. Svo

416 General Monthly Meeting. [April 5,

Smithsonian Institution — Annual Keport of the Board of Kegents of the Smith-
sonian Institution, to July, 1894. 8vo. 1896.
Society of Arts — Journal lor March, 1897. 8vo.
St, Petershourg, VAcademie Imperiale des Sciences — Me'moires, 8th Series,

Vol. III. Nos. 7-10 ; Vol. IV. Nos. 2-4 ; Vol. V. No. 1.
Bulletin, Tome III. Nos. 2-5; Tome IV. Nos. 1-5; Tome V. Nos. 1, 2. 8vo.

1895-96.
Tacchini, Prof. Hon. Mem. B.I. (the Author) — Memorie della Societa degli

Speitroscopisti Italiani, Vol. XXV. Disp. 11. 4to. 1S96.
United Service Institution, Royal — Journal for March, 1897. 8vo.
United States Department of Agriculture — Experiment Station Kecord, Vol. VIIL

No. 4. 8vo. 1896.
Monthly Weather Review for Dec. 1896. 8vo.
United States Patent 0^'ce— Official Gazette, Vol. LXXVII. Nos. 9-13; Vol.

LXXVIII. Nos. 1-3. 8vo. 1896.
United States Geological /S^Mrrey— Seventeenth Annual Report, 1895-96, Part 3.

(2 vols.). 4to. 1896.
Verein zur Beforderung des Geicerbfleisses in Preussen — Verhandluugen, 1897^

Heft 2. 4to.
Vienna, Geological Institute, Imperial — Verhandlungen, 1897, Nos. 1-3. Svo.
Wright, Messrs. J. & Co. (the Publishers) — The Medical Annual for 1897. 8vo.

1897.] The Bight Hon. Lord Eayleigh on Limits of Audition. 417

WEEKLY EVENING MEETING,

Friday, April 9, 1897.

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Honorary
Secretary and Vice-President, in the Chair.

The Eight Hon. Lord Rayletgh, M.A. D.C.L. LL.D. F.R.S. M.B.L
Professor of Natural Philosophy, B.I.

The Limits of Audition.

(Abstract.)

In order to be audible, sounds must be restricted to a certain range
of pitch. Thus a sound from a hydrogen flame vibrating in a large
resonator was inaudible, as being too low in pitch. On the other
side, a bird-call, giving about 20,000 vibrations per second, was
inaudible, although a sensitive flame readily gave evidence of the
vibrations and permitted the wave-length to be measured. Near
the limit of hearing the ear is very rapidly fatigued ; a sound in the
first instance loud enough to be disagreeable, disappearing after a
few seconds. A momentary intermission, due, for example, to a rapid
passage of the hand past the ear, again allows the sound to be heard.
The magnitude of vibration necessary for audition at a favourable
pitch is an important subject for investigation. The earliest estimate
is that of Boltzmann. An easy road to a superior limit is to find
the amount of energy required to blow a whistle and the distance to
which the sound can be heard (e.g. one-half a mile). Experiments
upon this plan gave for the amplitude 8 X 10~^ cm., a distance
which would need to be multiplied 100 times in order to make it
visible in any possible microscope. Better results may be obtained
by using a vibrating fork as a source of sound. The energy resident
in the fork at any time may be deduced from the amplitude as ob-
served under a microscope. From this the rate at which energy is
emitted follows when we know the rate at which the vibrations of
the fork die down (say to one-half). In this way the distance
of audibility may be reduced to 30 metres, and the results are less
liable to be disturbed by atmospheric irregularities. If s be the
proportional condensation in the waves which are just capable of
exciting audition, the results may be expressed: —

frequency == 256 j s = 6-0 x 10

„ = 384 p = 4-6 X 10

=r 512 ' s = 4-6 X 10

showing that the ear is capable of recognising vibrations which
involve far less changes of pressure than the total pressure out-
standing in our highest vacua.

418 Lord Bayleigh on the Limits of Audition. [April 9,

In sucli experiments the whole energy emitted is very small, and
contrasts strangely with the 60 horse-power thrown into the fog-
signals of the Trinity House. If we calculate according to the law of
inverse squares how far a sound absorbing 60 horse-power should be
audible, the answer is 2700 kilometres ! The conclusion plainly
follows that there is some important source of loss beyond the mere
diffusion over a larger surface. Many years ago Sir George Stokes
calculated the effect of radiation upon the propagation of sound. His
conclusion may be thus stated. The amplitude of sound propagated
in plane waves would fall to half its value in six times the interval
of time occupied by a mass of air heated above its surroundings in
cooling through half the excess of temperature. There appear to be
no data by which the latter interval can be fixed with any approach
to precision ; but if we take it at one minute, the conclusion is that
sound would be propagated for six minutes, or travel over about
seventy miles, without very serious loss from this cause.

The real reason for the falling off at great distances is doubtless
to be found principally in atmospheric refraction due to variation of
temperature, and of wind, with height. In a normal state of things
the air is cooler overhead, sound is propagated more slowly, and a
wave is tilted up so as to pass over the head of an observer at a
distance. [Illustrated by a model.] The theory of these effects has
been given by Stokes and Reynolds, and their application to the
explanation of the vagaries of fog signals by Henry. Progress would
be promoted by a better knowledge of what is passing in the atmo-
sphere over our heads.

The lecture concluded with an account of the observations of
Preyer upon the delicacy of pitch perception, and of the results of
Kohlrausch upon the estimation of pitch when the total number of
vibrations is small. In illustration of the latter subject an experi-
ment (after Lodge) was shown, in which the sound was due to the
oscillating discharge of a Leyden battery through coils of insulated
wire. Observation of the spark proved that the total number of
(aerial) vibrations was four or five. The effect upon the jiitch
of moving one of the coils so as to vary the self-induction was
very apparent.

1897.] Cathode Bays. 419

WEEKLY EVENING MEETING,

Friday, April 30, 1897.

' Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Honorary
Secretary and Vice-President, in tlie Chair.

Professor J. J. Thomson, M.A. LL.D. Sc.D. F.R.S.

Cathode Bays.

The first observer to leave any record of what are now known as
the Cathode Rays seems to have been Pliicker, who in 1859 observed
the now well known green phosphorescence on the glass in the
neighbourhood of the negative electrode. Pliicker was the first
physicist to make experiments on the discharge through a tube, in a
state anything approaching what we should now call a high vacuum :
he owed the opportunity to do this to his fellow townsman Geissler,
who first made such vacua attainable. Pliicker, who had made a
very minute study of the efifect of a magnetic field on the ordinary
discharge which stretches from one terminal to the other, distin-
guished the discharge which produced the green phosphorescence
from the ordinary discharge, by the difference in its behaviour when
in a magnetic field. Pliicker ascribed these phosphorescent jmtches
to currents of electricity which went from the cathode to the walls of
the tube, and then for some reason or other retraced their steps.

The subject was next taken up by Pliicker's pupil, Hittorf, who
greatly extended our knowledge of the subject, and to whom we owe
the observation that a solid body placed between a pointed cathode
and the walls of the tube cast a well defined shadow. This observa-
tion was extended by Goldstein, who found that a well marked,
though not very sharply defined shadow was cast by a small body
placed near a cathode of considerable area ; this was a very important
observation, for it showed that the rays casting the shadow came in
a definite direction from the cathode. If the cathode were replaced
by a luminous disc of the same size, this disc would not cast a shadow
of a small object placed near it, for though the object might intercept
the rays which came out normally from the disc, yet enough light
would be given out sideways from other parts of the disc to jDrevent
the shadow being at all well marked. Goldstein seems to have been
the first to advance the theory, which has attained a good deal of
prevalence in Germany, that these cathode rays are transversal
vibrations in the ether.

The physicist, however, who did more tlian any one else to direct
attention to these rays was Mr. Crookes, whose experiments, by their
beauty and importance, attracted the attention of all physicists to this

420 Professor J. J. Thomson [April 30,

subject, and who not only greatly increased our knowledge of the
properties of the rays, but by his application of them to radiant matter
spectroscopy has rendered them most important agents in chemical
research.

Eecently a great renewal of interest in these rays has taken place,
owing to the remarkable properties possessed by an offspring of theirs,
for the cathode rays are the parents of the Rontgen rays.

I shall confine myself this evening to endeavouring to give an
account of some of the more recent investigations which have been
made on the cathode rays. In the first place, when these rays fall on
a substance they produce changes physical or chemical in the nature
of the substance. In some cases this change is marked by a change
in the colour of the substance, as in the case of the chlorides of the
alkaline metals. Goldstein found that these when exposed to the
cathode rays changed colour, the change, according to E. Wiedemann
and Ebert, being due to the formation of a subchloride. Elster and
Geitel have recently shown that these substances become photo-
electric, i.e. acquire the power of discharging negative electricity
under the action of light, after exposure to the cathode rays. But
thougb it is only in comparatively few cases that the change pro-
duced by the cathode rays shows itself in such a conspicuous way as
by a change of colour, there is a much more widely spread phenomenon
which shows the permanence of the effect produced by the impact of
these rays. This is the phenomenon called by its discoverer. Prof.
E. Wiedemann, thermoluminescence. Prof. Wiedemann finds that
if bodies are exposed to the cathode rays for some time, when the
bombardment stops the substance resumes to all appearance its
original condition ; when, however, we heat the substance, we find
that a change has taken place, for the substance now, when heated,
becomes luminous at a comparatively low temperature, one far below
that of incandescence ; the substance retains this property for months
after the exposure to the rays has ceased. The phenomenon of
thermoluminescence is especially marked in bodies which are called
by Van t'Hoff solid solutions ; these are formed when two salts, one
greatly in excess of the other, are simultaneously precipitated from
a solution. Under these circumstances the connection between the
salts seems of a more intimate character than that existing in a
mechanical mixture. I have here a solid solution of CaSo^ with
trace of MnSo^, and you will see that after exposure to the cathode
rays it becomes luminous when heated. Another proof of the altera-
tion produced by these rays is the fact, discovered by Crookes, that
after glass has been exposed for a long time to the impact of these
rays, the intensity of its phosphorescence is less than when the rays
first began to fall upon it. This alteration lasts for a long time,
certainly for months, and Mr. Crookes has shown that it is able to
survive the heating up of the glass to allow of the remaking of the
bulb. I will now leave the chemical efiects produced by these rays,
and pass on to consider their behaviour when in a magnetic field.

1897.] on Cathode Bays. 421

First, let us consider for a moment the effect of magnetic force
on the ordinary discharge between terminals at a pressure much
higher than that at which the cathode rays begin to come off. 1 have

Fig. 1. Fig. 2,

here photographs (see Figs. 1 and 2) of the spark in a magnetic field.
You see that when the discharge, which passes as a thin bright line
between the terminals, is acted upon by the magnetic field, it is pulled
aside as a stretched string would be if acted upon by a force at right

Fig. 3. Fig. 4.

angles to its length. The curve is quite continuous, and though there^
may be gaps in the luminosity of the discharge, yet there are no
breaks at such points in the curve, into which the discharge is bent by
Vol. XV. (No. 91.) 2 f

422

Professor J. J. Thomson

[April 30,

a magnet. Again, if the discharge, instead of taking place between
points, passes between flat discs, the effect of the magnetic force is to
move the sparks as a whole, the sparks keeping straight until their
terminations reach the edges of the discs. The fine thread-like
discharge is not much spread out by the action of the magnetic field.
The appearance of the discharge indicates that when the discharge
passes through the gas it manufactures out of the gas something
stretching from terminal to terminal, which, unlike a gas, is capable of
sustaining a tension. The amount of deflection produced, other circum-
stances being the same, depends on the nature of the gas ; as the photo-
graphs (Figs. 3 and 4) show, the deflection is very small in the case
of hydrogen, and very considerable in the case of carbonic acid ; as a
general rule it seems smaller in elementary than in compound gases.

Fig. 5.— Hydrogen (Ammeter, 12 ; Vultmeter, 1600).

Let us contrast the behaviour of this kind of discharge under the
action of a magnetic field with that of the cathode rays. I have here
some photographs (Figs 5, 6 and 7) taken of a narrow beam formed
by sending the cathode rays through a tube in which there was a
plug with a slit in it, the plug being used as an anode and connected
with the earth, these rays traversing a uniform magnetic field. The
narrow beam spreads out under the action of the magnetic force into
a broad fan-shaped luminosity in the gas. The luminosity in this
fan is not uniformly distributed, but is condensed along certain lines.
The phosphorescence produced when the rays reach the glass is also
not uniformly distributed ; it is much spread out, showing that the
beam consists of rays which are not all deflected to the same extent

1897.]

071 Cathode Bays.

423

by the magnet. Thie luminous patch on the glass is crossed by bands
along which the luminosity is very much greater than in the adjacent

Fir.. G.— Air.

Fig. 7.— Carbonic Acid Gas (Ammeter, 12; Voltmeter, 1600).

parts. These bright and dark bands are called by Birkeland, who
first observed them, " the magnetic spectrum." The brightest places

2 F 2

424 Professor J. J. Thomson [April 30,

on the glass are by no means always the terminations of the brightest
streaks of luminosity in the gas; in fact, in some cases a very
bright spot on the glass is not connected with the cathode by any
appreciable luminosity, though there is plenty of luminosity in other
parts of the gas.

One very interesting point brought out by the photographs is
that in a given magnetic field, with a given mean potential dijBference
between the terminals, the path of the rays is independent of the
nature of the gas ; photographs were taken of the discharge in
hydrogen, air, carbonic acid, methyl iodide, i.e. in gases whose
densities range from 1 to 70, and yet not only were the paths of the
most deflected rays the same in all cases, but even the details, such
as the distribution of the bright and dark spaces, were the same ; in
fact, the photographs could hardly be distinguished from each other.
It is to be noted that the pressures were not the same ; the pressures
were adjusted until the mean potential difference was the same. When
the pressure of the gas is lowered, the potential difference between
the terminals increases, and the deflection of the rays produced by a
magnet diminishes, or at any rate the deflection of the rays where
the phosphorescence is a maximum diminishes. If an air break is
inserted in the circuit an effect of the same kind is produced. In
all the photographs of the cathode rays one sees indications of rays
which stretch far into the bulb, but which are not deflected at all by
a magnet. Though they stretch for some two or three inches, yet in
none of these photographs do they actually reach the glass. In some
experiments, however, I placed inside the tube a screen, near to the
slit through which the cathode rays came, and found that no appre-
ciable phosphorescence was produced when the non-deflected rays
struck the screen, while there was vivid phosphorescence at the places
where the deflected rays struck the screen. These non-deflected rays
do not seem to exhibit any of tLe characteristics of cathode rays, and
it seems possible that they are merely jets of uncharged luminous
gas shot out through the slit from the neighbourhood of the cathode
by a kind of explosion when the discharge passes.

The curves described by the cathode rays in a uniform magnetic
field are, very approximately at any rate, circular for a large part of
their course ; this is the path which would be described if the cathode
rays marked the path of negatively electrified particles projected with
great velocities from the neighbourhood of the negative electrode.
Indeed, all the effects produced by a magnet on these rays, and some
o^ these are complicated, as, for example, when the rays are curled up
into spirals under the action of a magnetic force, are in exact agree-
ment with the consequences of this view.

We can, moreover, show by direct experiment that a charge of
negative electricity follows the course of the cathode rays. One way
in which this has been done is by an experiment due to Perrin, the
details of which are shown in the accompanying figure (Fig. 8.) In
this experiment the rays are allowed to pass inside a metallic cylinder

1897.]

on Cathode Bays.

425

through a small hole, and the cylinder, when these rays enter it, gets
a negative charge, while if the rays are deflected by a magnet, so as
to escape the hole, the cylinder remains without charge. It seems
to me that to the experiment in this form it might be objected that,
though the experiment shows that negatively electrified bodies are
projected normally from the cathode, and are deflected by a magnet, it
does not show that when the cathode rays are deflected by a magnet
the path of the electrified particles coincides with the path of the
cathode rays. The supporters of the theory that these rays are waves

Earth

Fig. 8.

in the ether might say, and indeed have said, that while they did not
deny that electrified particles might be shot off from the cathode,
these particles were, in their opinion, merely accidental accompani-
ments of the rays, and were no more to do with the rays than the
bullet has with the flash of a rifle. The following modification of
Perrin's experiment is not, however, open to this objection: Two
co-axial cylinders (Fig. 9), with slits cut in them, the outer cylinder
being connected with earth, the inner with the electrometer, are
placed in the discharge tube, but in such a position that the cathode

Fig. 9.

rays do not fall upon them unless deflected by a magnet ; by means
of a magnet, however, we can deflect the cathode rays until they fall
on the slit in the cylinder. If under these circumstances the cylinder
gets a negative charge when the cathode rays fall on the slit, and
remains uncharged unless they do so, we may conclude, I think, the
stream of negatively- electrified particles is an invariable accompani-
ment of the cathode rays. I will now try the experiment. You
notice that when there is no magnetic force, though the rays do not
fall on the cylinder, there is a slight deflection of the electrometer,

426 Professor J, J. Thomson [April 30,

sliowing that it has acquired a small negative charge. This is, I
think, due to the plug getting negatively charged under the torrent
of negatively electrified particles from the cathode, and getting out
cathode rays on its own account which have not come through the
slit. I will now deflect the rays by a magnet, and you will see that
at first there is little or no change in the deflection of the electro-
meter, but that when the rays reach the cylinder there is at once a
great increase in the deflection, showing that the rays are pouring a
charge of negative electricity into the cylinder. The deflection of
the electrometer reaches a certain value and then stops and remains
constant, though the rays continue to pour into the cylinder. This
is due to the fact that the gas traversed by the cathode rays becomes
a conductor of electricity, and thus, though the inner cylinder is per-
fectly insulated when the rays are not passing, yet as soon as the rays
pass through the bulb the air between the inner cylinder and the
outer one, which is connected with the earth, becomes a conductor,
and the electricity escapes from the inner cylinder to the earth. For
this reason the charge within the inner cylinder does not go on con-
tinually increasing : the cylinder settles into a state of equilibrium
in which the rate at which it gains negative electricity from the rays
is equal to the rate at which it loses it by conduction through the air.
If we charge up the cylinder positively it rapidly loses its positive
charge and acquires a negative one, while if we charge it up negatively
it will leak if its initial negative potential is greater than its equili-
brium value.

I have lately made some experiments which are interesting from
the bearing they have on the charges carried by the cathode rays, as
well as on the production of cathode rays outside the tube. The
experiments are of the following kind. In the tube (Fig. 10) A and B
are terminals. C is a long side tube into which a closed metallic
cylinder fits lightly. This cylinder is made entirely of metal except
the end furthest from the terminals, which is stopped by an ebonite
plug, perforated by a small hole so as to make the pressure inside the
cylinder equal to that in the discharge tube. Inside the cylinder
there is a metal disc supported by a metal rod which passes through
the ebonite plug, and is connected with an electrometer, the wires
making this connection being surrounded by tubes connected with
the earth so as to screen off electrostatic induction. If the end of
the cylinder is made of thin aluminium about -^Q^h. of a millimetre
thick, and a discharge sent between the terminals, A being the cathode,
then at pressures far higher than those at which the cathode rays
come off, the disc inside the cylinder acquires a positive charge. And
if it is charged up independently the charge leaks away, and it leaks
more rapidly when the disc is charged negatively than when it is
charged positively ; there is, however, a leak in both cases, showing
that conduction has taken place through the gas between the cylinder
and the disc. As the pressure in the tube is diminished the positive
charge on the disc diminishes until it becomes unappreciable. The

1897.]

on Cathode Bays.

427

leak from the disc when it is charged still continues, and is now
equally rapid, whether the original charge on the disc is positive or
negative. When the pressure falls so low that cathode rays begin to
fall on the end of the cylinder, then the disc acquires a negative
charge, and the leak from the disc is more rapid when it is charged
positively than when it is charged negatively. If the cathode rays
are pulled off the end of the cylinder by a magnet, then the negative
charge on the disc and the rate of leak from the disc when it is posi-
tively charged is very much diminished. A very interesting point
is that these effects, due to the cathode rays, are observed behind
comparatively thick walls. I have
here a cylinder whose base is
brass about 1 mm. thick, and yet
when this is exposed to the
cathode rays the disc behind it
gets a negative charge, and leaks
if charged positively. The effect
is small compared with that in
the cylinder with the thin alu-
minium base, but is quite appre-
ciable. With the cylinder with
the thick end I have never been
able to observe any effect at the
higher pressures when no cathode
rays were coming off. The effect
with the cylinder with the thin
end was observed when the dis-
charge was produced by a large
number of small storage cells, as
well as when it was produced by
an induction coil.

Eiirlfi

Electrometer

Fig. 10.

It would seem from this experiment that the incidence of the
cathode rays on a brass plate as much as 1 mm. thick, and connected
with the earth, can put a rarefied gas shielded by the plate into a con-
dition in which it can conduct electricity, and that a body placed
behind this screen gets a negative charge, so that the side of the
brass away from the cathode rays acts itself like a cathode though
kept permanently to earth. In the case of the thick brass the effect
seems much more likely to be due to a sudden change in the potential
of the outer cylinder at the places where the rays strike, rather than
to the penetration of any kinds of waves or rays. If the discharge in
the tube was perfectly continuous the potential of the outer cylinder
would be constant, and since it is connected to earth by a wire through
which no considerable current flows, the potential must be approxi-
mately that of the earth. The discharge there cannot be continuous ;
the negative charge must come in gusts against the ends of the
cylinder, coming so suddenly that the electricity has no time to dis-
tribute itself over the cylinder so as to shield off the inside from the

428 Professor J. J. Thomson [April 30,

electrostatic action of the cathode rays ; this force penetrates the
cylinder and produces a discharge of electricity from the far side
of the brass.

Another efifect which I believe is due to the negative electrifica-
tion carried by the rays is the following. In a very highly exhausted
tube provided with a metal plug, I have sometimes observed, after
the coil has been turned off, bright patches on the glass ; these are
deflected by a magnet, and seem to be caused by the plug getting
such a large negative charge that the negative electricity continues to
stream from it after the coil is stopped.

An objection sometimes urged against the view that these cathode
rays consist of charged particles, is that they are not deflected by an
electrostatic force. If, for example, we make, as Hertz did, the rays
pass between plates connected with a battery, so that an electrostatic
force acts between these plates, the cathode ray is able to traverse
this space without being deflected one way or the other. "We must
remember, however, that the cathode rays, when they pass through a
gas make it a conductor, so that the gas acting like a conductor
screens off the electric force from the charged particle, and when the
plates are immersed in the gas, and a definite potential difference
established between the plates, the conductivity of the gas close to
the cathode rays is probably enormously greater than the average
conductivity of the gas between the plates, and the potential gradient
on the cathode rays is therefore very small compared with the average
potential gradient. We can, however, produce electrostatic results if
we put the conductors which are to deflect the rays in the dark space
next the cathode. I have here a tube in which, inside the dark space
next the cathode, two conductors are inserted ; the cathode rays start
from the cathode and have to pass between these conductors ; if,
now, I connect one of these conductors to earth there is a decided
deflection of the cathode rays, while if I connect the other electrode
to earth there is a deflection in the opposite direction. I ascribe this
deflection to the gas in the dark space either not being a conductor
at all, or if a conductor, a poor one compared to the gas in the
main body of the tube.

Goldstein has shown that if a tube is furnished with two cathodes,
when the rays from one cathode pass near the other they are repelled
from it. This is just what would happen if the dark space round the
electrode were an insulator, and so able to transmit electrostatic
attractions or repulsions. To show that the gas in the dark space
differs in its properties from the rest of the gas, I will try the follow-
ing experiment. I have here two spherical bulbs connected together
by a glass tube ; one of these bulbs is small, the other large ; they
each contain a cathode, and the pressure of the gas is such that the
dark space round the cathode in the small bulb completely fills the
bulb, while that round the one in the larger bulb does not extend
to the walls of the bulb. The two bulbs are wound with wire, which
connects the outsides of two Ley den jars ; the insides of these jars

1897.] on Cathode Bays. 429

are connected with the terminals of a Wimshurst machine. When
sparks pass between these terminals currents pass through the wire
which induce currents in the bulbs, and cause a ring discharge to
pass through them. Things are so arranged that the ring is faint in
the larger bulb, bright in the smaller one. On making the wires in
these bulbs cathodes, however, the discharge in the small bulb, which
is filled by the dark space, is completely stopped, while that in the
larger one becomes brighter. Thus the gas in the dark space is
changed, and in the opposite way from that in the rest of the tube.
It is remarkable that when the coil is stopped the ring discharge on
both bulbs stops, and it is some time before it starts again.

The deflection excited on each other by two cathodic streams
would seem to have a great deal to do with the beautiful phosphor-
escent figures which Goldstein obtained by using cathodes of different
shapes. I have here two bulbs containing cathodes shaped like a
cross ; they are curved, and of the same radius as the bulb, so that if
the rays came off these cathodes normally the phosphorescent picture
ought to be a cross of the same size as the cathode, instead of being
of the same size. You see that in one of these bulbs the image of
the cross consists of two large sectors at right angles to each other,
bounded by bright lines, and in the other, which is at a lower pres-
sure, the geometrical image of the cross, instead of being bright, is
dark, while the luminosity occupies the space between the arms of the
cross.

So far I have only considered the behaviour of the cathode rays
inside the bulb, but Lenard has been able to get these rays outside
the tube. To this he let the rays fall on a window in the tube, made
of thin aluminium about y^o th of a millimetre thick, and he found
that from this window there proceeded in all directions rays which
were deflected by a magnet, and which produced phosphorescence
when they fell upon certain substances, notably upon tissue paper
soaked.in a solution of pentadekaparalolylketon. The very thin alu-
minium is difficult to get, and Mr. McClelland has found that if it is
not necessary to maintain the vacuum for a long time, oiled silk
answers admirably for a window. As the window is small the phos-
phorescent patch produced by it is not bright, so that I will show
instead the other property of the cathode rays, that of carrying with
them a negative charge. I will place this cylinder in front of the
hole, connect it with the electrometer, turn on the rays, and you will
see the cylinder gets a negative charge ; indeed this charge is large
enough to produce the well known negative figures when the rays fall
on a piece of ebonite which is afterwards dusted with a mixture of
red lead and sulphur.

From the experiments with the closed cylinder we have seen that
when the negative rays come up to a surface even as thick as a milli-
metre, the opposite side of that surface acts like a cathode, and gives
off the cathodic rays ; and from this point of view we can understand
the very interesting result of Lenard that the magnetic deflection of

430

Professor J. J. Thomson

[April 30,

the rays outside tlie tube is independent of the density and chemical
composition of the gas outside the tube, though it varies very much
with the pressure of the gas inside the tube. The cathode rays could
be started by an electric impulse which would depend entirely on
what was going on inside the tube ; since the impulse is the same
the momeutam acquired by the particles outside would be the same ;
and as the curvature of the path only depends on the momentum, tbe
path of these particles outside the tube would only depend on the
state of aifairs inside the tube.

The investigation by Lenard on the absorption of these rays shows
that there is more in his experiment than is covered by this considera-
tion. Lenard measured the distance these rays would have to travel
before the intensity of the rays fell to one-half their original value.
The results are given in the following table : —

Substance.

Hydrogen (3 mm. press.)

(760) .. ..
Air (0-760 mm. press.)

SO2

Collodion

Glass

Aluminium

Silver

Gold

Coefficient of
Absorption.

0-00149

0-476

3-42

8-51
3,310
7,810
7,150

32,200

53,600

Density.

0-000000368
0-0000484
0-00123
0-00271

Absorption
Density

4040
5640
2780
3110
3010
3160
2650
3070
2880

We see that though the densities and the coefficient of absorption
vary enormously, yet the ratio of the two varies very little, and the
results justify, I think, Lenard's conclusion that the distance through
which these rays travel only depends on the density of the substance
— that is, the mass of matter per unit volume, and not upon the
nature of the matter.

These numbers raise a question which I have not yet touched
upon, and that is the size of the carriers of the electric charge. Are
they or are they not the dimensions of ordinary matter ?

We see from Lenard's table that a cathode ray can travel through
air at atmospheric pressure a distance of about half a centimetre
before the brightness of the phosphorescence falls to about one-half
of its original value. Now the mean free path of the molecule of air
at this pressure is about 10-^ cm., and if a molecule of air were pro-
jected it would lose half its momentum in a space comparable with
the mean free path. Even if we suppose that it is not the same molecule
that is carried, the eflFect of the obliquity of the collisions would
reduce the momentum to one-half in a short multiple of that path.

Thus, from Lenard's experiments on the absorption of the rays
outside the tube, it follows on the hypothesis that the cathode rays

1897.] on Cathode Bays. 431

arc charged particles moving with high velocities, that the size of
the carriers must be small compared with the dimensions of ordinary-
atoms or molecules. The assumption of a state of matter more finely
subdivided than the atom of an element is a somewhat startling one ;
but a hypothesis that would involve somewhat similar consequences
— viz. that the so-called elements are compounds of some primordial
element — has been put forward from time to time by various chemists.
Thus, Prout believed that the atoms of all the elements were built up
of atoms of hydrogen, and Mr. Norman Lockyer has advanced weighty
arguments, founded on spectroscopic consideration, in favour of the
composite nature of the elements.

Let us trace the consequence of supposing that the atoms of the
elements are aggregations of very small particles, all similar to each
other ; we shall call such particles corpuscles, so that the atoms of
the ordinary elements are made up of corpuscles and holes, the holes
being predominant. Let us suppose that at the cathode some of the
molecules of the gas get split up into these corpuscles, and that these,
charged with negative electricity and moving at a high velocity, form
the cathode rays. The distance these rays would travel before losing
a given fraction of their momentum would be proportional to the
mean free path of the corpuscles. Now, the things these corpuscles
strike against are other corpuscles, and not against the molecules as
a whole ; they are supposed to be able to thread their way between
the interstices in the molecule. Thus the mean free path would be
proportional to the number of these corpuscles ; and, therefore, since
each corpuscle has the same mass to the mass of unit volume — that
is, to the density of the substance, whatever be its chemical nature
or physical state. Thus the mean free path, and therefore the co-
efficient of absorption, would depend only on the density; this is
precisely Lenard's result.

We see, too, on this hypothesis, why the magnetic deflection is
the same inside the tube whatever be the nature of the gas, for the
carriers of the charge are the corpuscles, and these are the same
whatever gas be used. All the carriers may not be reduced to their
lowest dimensions; some may be aggregates of two or more cor-
puscles ; these would be differently deflected from the single corpuscle,
thus we should get the magnetic spectrum.

I have endeavoured by the following method to get a measure-
ment of the ratio of the mass of these corpuscles to the charge
carried by them. A double cylinder with slits in it, such as that
used in a former experiment, was placed in front of a cathode which
was curved so as to focus to some extent the cathode rays on the
slit ; behind the slit, in the inner cylinder, a thermal junction was
placed which covered the opening so that all the rays which entered
the slit struck against the junction, the junction got heated, and
knowing the thermal capacity of the junction, we could get the
mechanical equivalent of the heat communicated to it. The deflec-
tion of the electrometer gave the charge which entered the cylinder.

432 Professor J. J. Thomson on Cathode Bays. [April 30,

Thus, if there are N particles entering the cylinder each with a
charge e, and Q is the charge inside the cylinder,

Ne=Q.
The kinetic energy of these

4Nm«;2 = W

where W is the mechanical equivalent of the heat given to the

thermal junction. By measuring the curvature of the rays for a

magnetic field, we get

m

— v=l.

e

Thus

e ~ 2 W *

In an experiment made at a very low pressure, when the rays
were kept on for about one second, the charge was sufficient to raise
a capacity of 1'5 microfarads to a potential of 16 volts. Thus

Q = 2-4 X 10-^

The temperature of the thermo junction, whose thermal capacity
was 0 • 005 was raised 3 • 3° C. by the impact of the rays, thus

W = 3-3 X 0-005 X 4-2 X W
= 6-3 X 10^

The value of I was 280, thus

^ = 1-6X 10-^
e

This is very small compared with the value 10"'' for the ratio of
the mass of an atom of hydrogen to the charge carried by it. If
the result stood by itself we might think that it was probable that
e was greater than the atomic charge of atom rather than that m
was less than the mass of a hydrogen atom. Taken, however, in
conjunction with Lenard's results for the absorption of the cathode
rays, these numbers seem to favour the hypothesis that the carriers
of the charges are smaller than the atoms of hydrogen.

It is interesting to notice that the value of e/m, which we have
found from the cathode rays, is of the same order as the value lO'""^
deduced by Zeeman from his experiments on the effect of a magnetic
field on the period of the sodium light.

[J.J.T.]

1897.] Annual Meeting, 433

ANNUAL MEETING,

Saturday, May 1, 1897.

Sir James Ceichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Annual Report of the Committee of Visitors for the year
1896, testifying to the continued prosperity and efficient management
of the Institution, was read and adopted.

Fifty-eight new Members were elected in 1896.

Sixty-four Lectures and Nineteen Evening Discourses were
delivered in 1896.

The Books and Pamphlets presented in 1896 amounted to about
274 volumes, making, with 621 volumes (including Periodicals bound)
purchased by the Managers, a total of 895 volumes added to tlie
Library in the year.

Thanks were voted to the President, Treasurer, and the Honorary
Secretary, to the Committees of Managers and Visitors, and to the
Professors, for their valuable services to the Institution during the
past year.

The following Gentlemen were unanimously elected as Officers
for the ensuing year :

President — The Duke of Northumberland, K.G. D.C.L. LL.D.
Treasurer — Sir James Crichton-Browne, M.D. LL.D. F.H.S.
Secuetary— Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S.
M. Inst. C.E.
Manager^!. i Visitors.

Sir Frederick Abel, Bart. K.C.B. D.C.L. LL.D. Sir James Blyth, Bart.

F.R.S. William Arthur Brailey, M.D. M.R.C.S.

The Right Hon. Arthur James Balfour, M.P. Edward Dent, Esq.

D.C.L. LL.D. F.R.S. i John Ambrose Fleming, Esq. M A D Sc F R S

John Wolfe Barry, Esq. C.B. F.R.S. M.Inst. C.E. | Edward Kraftmeier, Esq.
William Crookes, Esq. F.R.S. Sir Francis Laking, M.D.

Edward Frankland, E^iq. D.C.L. LL.D. F.R.S. : Hugh Leonard, Ksq. M. Inst. C.E.
Charles Hawksley, Esq. M. Inst. C.E. Sir Philip Magnus, J.P.

Donald William Charles Hood, M.D. F.R.C.P. \ T. Lambert Mears, Esq. M.A. LL.D.

Victor Horsley, Esq, M.B. F.R.S, F.R.C.S. ' Lachlan Mackintosh Kate, Esq. M.A.

William Huggins, Esq. D.C.L. LL.D. F.R.S. I Thomas Tyrer, Esq. F.CS. F.I.C, *
The Right Hon. Lord Lister, M.D. D.C.L. LL.D. Roger William Wallace, Esq. Q.C.

Pres. R.S, John Westlake, Esq. Q.C. LL.D.

Ludwig Mond, Esq. Ph.D. F.R.S. His Honour Judge Frederick Meadows White

Arthur William hdcker, Esq. M.A. D.Sc. F.R.S. ■ Q.C.

Basil Woodd Smith, Esq. F.R.A.S. F.S.A,
The Hon. Sir James Stirling, M.A. LL.D.
Sir Henry Thompson, F.R.C.S. F.Pt.A.S.

James Wimshurst, Esq.

434 General Monthly Meeting. [May 3,

GENERAL MONTHLY MEETING.

Monday, May 3, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.E.S. Treasurer and
Vice-President, in the Chair.

Charles Elmer Southwell, Esq.
Mrs. Silvanus P. Thompson,

were elected Members of the Royal Institution.

The Right Hon. Lord Rayleigh was re-elected Professor of
Natural Philosophy in the Royal Institution.

The Presents received since the last Me'^ting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

The Secretary of State for J?ztZia— Archaeological Survey of India, Vol. VL The

Muhammadan Architecture of Bharoch, Cambay, Dholka Champanir and

Gujarat. By J. Burgess. 1896. 4to.
The Governor-General of JnfZm— Geological Survey of India : Records, Vol. XXX.

Part 1. 8vo. 1897.
The Meteorological Office— Ueport of the Meteorological Council to the Koyal

Society. Svo. 1896.
Accademia dei Lincei, Reale, Roma — Classe di Scienze Fisiche, Matematiche e

Naturali. Atti, Serie Quinta : Eendiconti. 1" Semestre, Vol. VI. Fasc. 6,7.

Classe di Scienze Morali, etc. Serie Quinta, Vol. VI. Fasc. 1. 8vo. 1897.
American Association for the Advancement of Science — Proceedings, 45tli Meeting

at Buffalo, N.Y. 1896. 8vo. 1897.
American Academy of Arts and Sciences — Proceedings, New Series, Vol. XXII.

Nos. 2-4. 8vo. ' 1896-97.
Memoirs. Vol. XII. Nos. 2, 3. 4to. 1896.
American Geographical Society— BuWetm, Vol. XXIX. No. 1. 8vo. 1897.
Asiatic Society, Royal — Journal for April, 1897. 8vo.

Astronomical Society, Royal — Monthly Notices, Vol. LVII. No. 5. 8vo. 1897.
Bankers, Institute o/— Journal, Vol. XVIII. Part 4. 8vo. 1897.
Birkett, John, Esq. F.R.C.S. M.R.I. — Des Ide'es Napoleoniennes. Par le Prince

Napoleon-Louis Bonaparte. 8vo. 1839.
Boston Public Library— MowiXAy Bulletin, Vol. II. No. 4. 8vo. 1897.
Botanic Society, ii'oj/aZ— Quarterly Ptecord, Vol. VI. No. 68. 8vo. 1896.
Bouloqne-sur-mer, Chambre de Commerce — Woiks at the Port of Boulogne and

Plans, fol. 1896.
British Architects, Royal Institute o/— Journal, 3rd Series, Vol. IV. Nos. 11, 12.

4to. 1897.
British Astronomical Assorialion — Memoirs, Vol. VI. Part 2. 8vo. 1897.

Journal. Vol. VII. No. 5. 8vo. 1897.
Camera C/it6— Journal for April, 1897. 8vo.

Chemical Industry, Society o/"— Journal, Vol. XVI. No. 3. 8vo. 1897.
Chemical Society — Journal for March-April, 1897. 8vo.

Proceedings, Index to Vol. XII. 8vo. 1897.
Cracovie, V Academic des Sciences— BnWet'm, 1897, No. 2. 8vo.
Cutter, Ephraim, Esq. LL.D. — Various Papers on Medical Subjects. 8vo. 1897.

1897.]

General Monthly Meeting.

435

Dax : Soci^te de Borda — Annee 1896, Troisieme Trimestre. 8vo. 1896.
East India Association — Journal, Vol. XXIX. No. 9. 8vo. 1897.
Editors — American Journal of Science for April, 1897. 8vo.

Analyst for April, 1897. 8vo.

Anthony's Photographic Bulletin for April, 1897. 8vo.

Astrophysical Journal for April, 1897. 8vo.

Athenaeum for April, 1897. 4to.

Author for April, 1897. 8vo.

Bimetallist for April, 1897.

Brewers' Journal for April, 1897. 8vo.

Chemical News for April, 1897. 4to.

Chemist and Druggist for April, 1897. 8vo.

Education for April, 1897.

Electrical Engineer for April, 1897. fol.

Electrical Engineering for April, 1897. 8vo.

Electrical Keview for April, 1897. 8vo.

Electricity for April, 1897. 8vo.

Engineer for April, 1897. fol.

Engineering for April, 1897. fol.

Homceopathic Review for April, 1897. 8vo.

Horological Journal for April, 1897. 8vo.

Industries and Iron for April, 1897. fol.

Invention for April, 1897.

Journal of Physical Chemistry for April, 1897.

Journal of State Medicine for April, 1897. 8vo.

Law Journal for April, 1897. 8vo.

Lightning for April, 1897. 8vo.

London Technical Education Gazette for April, 1897. 8vo.

Machinery Market for April, 1897. 8vo.

Monist for April, 1897.

Nature for April, 1897. 4to.

New Book List for April, 1897. 8vo.

New Church Magazine for April, 1897. 8vo.

Nuovo Cimento for March, 1897. 8vo.

Photographic News for April, 1897. 8vo.

Science Sittings for April, 1897.

Terrestrial Magnetism for March, 1897. 8vo.

Transport for April, 1897. fol.

Travel for April, 1897.

Tropical Agriculturist for April, 1897.

Zoophilist for April, 1897. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXV. No. 127. 8vo. 1897.
Florence, Bihlioteca Nazionale Centrale — Bolletino, Nos. 271, 272. 8vo. 1897.
Florence, Beale Accademia dei Georgofili — Atti, Quarta Serie, Vol. XX. Disp. 1 .

8vo. 1897.
Franklin Institute— J ouvnaA for April, 1897. 8vo.

Geographical Society, Royal — Geographical Journal for April, 1897. Svo.
Barlem, Societe Hollandaise des Sciences— Archives Ne'erlandaises, Tome XXX.

Livr. 5«. 8vo. 1897.
Historical Society, Boyal — The Domesday of Enclosures, 1517-1518, being the
extant returns to Chancery for Berks, Bucks, Cheshire, Essex, Leicestersljire,
Lincolnshire, North Hants, Oxon, Warwickshire, by the Commissioners of
Enclosures in 1517, and for Bedfordshire in 1518; together with Dugdale's
MS. Notes of the Warwickshire Inquisitions in 1517, 1518 and 1549. Edited
by J. S. Leadam. 2 vols. 8vo. 1897.
Horticultural Society, Eoyal— J omnal, Vol. XX. Part 3. 8vo. 1897.
Hughes, W. C. Esq. — The Art ot Projection and complete Magic-Lantern Manual.
By an Expert. Svo. 1893.

436 General Monthly Meeting. [May 3,

Imperial Institute — Imperial Institute Journal for April, 1897.

Japan, Imperial University College of Science — Journal, Vol. IX. Part 2. 4to. 1897.

Johns Hopkins University — Americaa Chemical Journal, Vol. XIX. No. 4 (April).

8vo. 1897.
Linnean Society— SonrnQi\ Nos. 166-219. 8vo. 1897.
Lubbock, Sir John, Bart. M.P. FM.S. M.R.I.— The Scenery of Switzerland and

the causes to which it is due. 8vo. 1896.
Madras Government Museum — Bulletin (Anthropology), Vol. II. No. 1. 8vo.

1897.
Madrid, Royal Academy of Sciences — Anuario for 1897. 8vo.
Navy League — Navy League Journal for April, 1897. 8vo.
Nova Scotian Institute of Science — Proceedings and Transactions, Vol. IX. Part 2.

8vo. 1896.
Odontological Society of Great Britain — Transactions, Vol. XXIX. No. 6. 8vo.

1897.
Paris, Society Frangaise de Physique — Bulletin, No. 94. 8vo. 1897.
Pharmaceutical Society of Great Britain — Journal for April, 1897. 8vo.
Photographic Society, Royal — Photographic Journal for Marcli, 1897. 8vo.
Physical Society of Lonc?o/i— Proceedings, Vol. XV. Part 4. 8vo. 1897.
Queen's College, GuZim?/— Calendar for 1896-97. 8vo. 1897.
Rochechouart. La Societe'des Amis des Sciences et Arts — Bulletin, Tome VI. Nos.

3, 4. 8vo. 1896.
Royal Society of Lo/ifZon— Proceedings, No. 370. 8vo. 1897.

Philosophical Transactions, Vol. CLXXXVIII. B. No. 143 ; Vol.CLXXXIX. A.

No. 192. 4to. 1897.
Russell, Tlie Hon. F. A. Rollo, F.R.Met.Soc. M.R.I (the Author)~The Atmosphere

in relation to Human Life and Health. (Smithsonian Miscellaneous Collec-
tions, No. 1072. Hodgkins Fund.) Washington. 8vo. 1896.
Sanitary Institute— J oumsil, Vol. XVIII. Part 1. 8vo. 1897.
Saxon Society of Sciences, Royal —
Mathematisch-Physische Classe —

Berichte, 1896, Nos. 5, 6. 8vo. 1897.

Abhandlungen, Band XXIII. No. 6. 8vo. 1897.
Scottish Microscopical Society — Proceedings, Vol. II. No. 1. 8vo. 1895-96.
Selborne Society — Nature Notes for April, 1897. 8vo.
Sidgreaves, The Rev. W. S. J. F.R.A.S. — Results of Meteorological, Magnetical

and Solar Observations at Stonyhurst College Observatory, 1896. 8vo. 1897.
Singh, The Hon. Maharaj Pratap Narain — Raskusumakar ; or a Book on

Rhetoric. By the Hon. Maharaja Pratap Narayan Singh Bahadur, of

Ayodhya. 8vo. 1894.
Soriety of ^rfs— Journal for April, 1897. 8vo.
Statistical Society, Royal— Jomna\, Vol. LX. Part 1. 8vo. 1897.
St. Petersburg, Acade'mie Imperiale des Sciences — Bulletin, V® Se'rie, Tome VI.

No. 2. 8vo. 1897.
Tacchini, Prof. P. Hou.Mem.R.I (the Author) — Memorie della Societa degli Spet-

troscopisti Italiani, Vol. XXV. Disp. 12. fol. 1896.
Toulouse, Societe Archeologique du Midi de la France — Bulletin, Serie in 8vo.

Nos. 17, 18. 8vo. 1«96.
United Service Institution, Royal — Journal for April. 8vo. 1897.
United States Department of Agriculture— 'Monthly Weather Review for Jan.

1897. 8vo.
Experiment Station Record, Vol. VII. No. 12 ; Vol. VIII. No. 5. 8vo. 1897.
Experiment Station Bulletin, No. 37. 8vo. 1897.
United States Patent O^^ce— Official Gazette, Vol. LXXVIII. Nos. 4-7. 8vo.

1897.
Annual Report of the Commissioner of Patents for 1895. 8vo. 1896.
Verein zur Beforderung des Gewerbfleisses in Preussen — Verhandlungen, 1897,

Heft 3. 4to.

1897.] General Monthly Meeting. 437

Vienna, Imperial Geological Institute -Verhandlungen, 1897, Nos. 4, 5. Svo.
Yorkshire Archseological Society -The Yorkshire AvcluTeological Journal, Part 55.

Svo. 1897.
Zoological Society— Proceeduige, 1896, Part 4, Svo. 1897.

Transactions, Vol. XIV. Part 3. 4to. iS97.
Zurich, Naturforschende GeseZZsc7m/<— Vierteljahrsschrift, Jahrg. XLI. Suppl.
Svo. 1896.
Neujahrsblatt, No. 99. 4to. 1897.

Vol. XV, (No. 91.) 2 g

438 Mr. Anthony Hope Hawkins [May 7,

WEEKLY EVENING MEETING,

Friday, May 7, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Anthony Hope Hawkins, Esq.

Romance.

My object in the remarks which I am to have the honour of addressing
to you to-night is to attempt to define in some degree the meaning and
function of romance as a quality in literature ; and although romance
is to be found in many kinds of literature, I think you will not only
forgive, but will also approve, if I discuss it from the point of view
of the species on which alone even your indulgence could seem to
give me any right to speak — that of prose fiction. As regards nomen-
clature, there is at the present time a tendency in some quarters to
distinguish between novels and romances ; but I think that the older
and more authoritative usage in English is to employ novel as the
generic, romance as the specific term. In this latter way I shall use
the words to-night ; and I shall ask, to put my questions broadly,
What are the characteristics whose presence in a novel leads us to
call that novel a romance ; and what is the share of romance, as a
quality, in the work that novels have to do ? The terms which are
popularly opposed to romance — realism and the realistic — I shall not
deal with further than in so far as they may occur incidentally in the
course of my proper inquiry. It may be doubted whether the anti-
thesis, admittedly rough and ready, is not in fact so partial and so
clumsy as to be devoid of any merit as a guide in thinking, though it
may by familiarity have acquired some convenience as a catchword.
Speaking in a place mainly devoted to the study of exact sciences,
I would add that I must beg for some allowance if, in treating of a
subject of an inexact nature, and of an art not very amenable to strict
rules, my conclusions are affected by a certain degree of vagueness
and tentativeness. The true meaning which underlies ordinary
phraseology is not always easy to discover, and rigid dogmatism of
statement would befit neither the topic nor the speaker. At the same
time I may here and there, owing to a desire for brevity, seem to
assert, where my real intent is only to suggest matter for your con-
sideration.

Romance, then, being a certain quality in literature, and literature
being (so far, anyhow, as novels represent it) a picture of some side
or aspect of life — for these two preliminary steps in the argument it
seems safe to assume — the presence or absence of romance must be

1897.J on Bomance. 439

due either to the choice of the aspect, or to its treatment, or to a
combination of these two. Now every novel which (if I may use the
phrase) knows its own mind, may be analysed into, first, the theme,
and secondly, the things which exist for the sake of the theme — the
auxiliaries ; that is to say, into the thing which it was the writer's
end and object to exhibit, and the various means and devices by which
he endeavours to make the exhibition of it as clear, as complete, and
as striking as possible. For the essential character of the book we
must look not at the auxiliaries but at the theme ; indeed it is not
a rare case that much of the auxiliaries should be in violent contrast
with the theme, seeking that means of heightening the theme's effect.
We should go very wrong, then, if we judged the character of the book
from them : it is always the theme which decides that. To put it
briefly, the auxiliaries subserve the theme, the theme classes the book.

Again, the theme is not concerned with incidents as such. I
need not approach the borders of metaphysics and ask whether there
is any such thing as an incident as such, or could be ; I am happily
at liberty to waive that question, and to content myself with observing
that at any rate incidents as such — incidents not in relation to a mind
perceptive of them, I mean — are not the subject of novels. The theme
deals with people passing through incidents, and shows how they are
affected thereby : their thoughts, feelings, emotions, and volitions.
The incidents are means, not ends, and, to use the common metaphor,
just as truly a background to the picture as any particular locality or
any historical period which the writer may select for the staging of his
story. The truth of this, if not self-evident, yet becomes immediately
apparent when we observe that we can go a very long way towards
changing incidents, or even towards dispensing entirely with external
incidents, without affecting the identity of the theme ; but we can
take hardly a single step in the direction of changing the character
of the people with whom the theme is concerned : it becomes plain
at once that a pursuit of that path will end by depriving us altogether
of what we set out to tell, and leaving us either with no story at all
or with a very different one. Novels, then, are not about things or
incidents, but about people. It may be objected that they are also,
in some cases, about non-human animals- Yes, but only when such
animals are treated as people — that is to say, with an artificiality
which the writer's talent makes us accept in spite of a more or less
obstinate sense of ultimate falsity.

It follows that the quality which is the subject of my inquiry,
since it is to be found in the theme, must be found in the people and
not in the incidents. Here common ways of speaking and thinking
seem to be to some extent against us. When the ordinary man —
when anybody who is not at the moment trying or caring to think
exactly — speaks of a romance, no doubt he most often has external in-
cidents in his mind ; he thinks of fighting perhaps,

" the lance points slantingly —
Athwart the morning air."

2 G 2

440 Mr. Anthony Hope Hawlcins [May 7,

Or perhaps ho has in his mind murders and dark intrigues. None
the less he does not mean the same thing when he says " A
Romance " as he does when he says " A Detective Story." Nor
does he really mean to assert the necessary introduction of im-
probability of incident, '-r of " sensati- )ns," or of strange scenes
or strange places — though he would say that all these things
were certainly often present in romances, and we should be
obliged to admit the justice of his remark Or perhaps he would
maintain that a plentiful supply of love making is the hall-mark of
the romance ; and again we sliould agree that love-making is very
common and is apt to be a predominant subject in romance. But he
would admit on reflection that there might be a romance of ambition,
or of religious emotion, or of devotion to truth, or of the love of
humanity. His mistake, in fact, would seem to be the very ordinary
one of taking separable, though frequent, accidents for the essence.
And it is worth noticing that the common speech is sometimes more
nearly right. If I say of a man, " He hasn't a bit of romance in
him," I do not mean that nothing happens to him — the Tower of
Siloam would fall on romantic and unromantic alike. Nor do I mean
that he never makes love. He may make it very often. I am
characterising the quality of the man's mind, not his fortunes or his
doings. We shall see later on, perhaps, how the venial error of every-
day speech finds its excuse.

The theme in which we are to discover the romance is concerned,
then, not with things or with incidents but with people. But it is
concerned only with parts of people. Sometimes we read of a book,
" It shows us the whole man," and the remark is meant as praise.
But it is not to be read literally, or it is not praise. You must add
to it, " so far as relevant to the theme." No book should, or perhaps
could, show the whole man any more than it should show his whole
life. This is familiar ground, and I need not labour it. A book
shows more or less of a man, first, in relation to a similar more or less
of other people, and secondly, as acted on by the chosen incidents,
not by all that happens to him, for the greater part of that either
has no material influence at all, or such a common and obvious one
that the exj^erience of the reader may safely be left to presuppose it.
Certain feelings of a man or several men are the theme of a novel,
and are therefore the place in which romance is to be found or the
absence of it to be noted.

But does romance lie in the choice of these feelings or in the
treatment of them ? The question cannot be answered quite simply.
Not in the choice in one sense, for probably any sort of emotion might
be selected, nor merely in the treatment, for there must be a material
of the appropriate nature. Miserliness does not sound like a good
subject for romance, yet there might be a romance of miserliness ;
but it would have to be miserliness in excelsis, and unless it were, no
skill of treatment would make a romance out of the theme. We must
answer, I think, that the basis of romance is to be found in the choice

1897J on Romance. 441*

of a special case of some emotion, and in imparting to it certain
special qualities by means of treatment.

And first in romance, the emotion is taken at a higli pitch. It is
strong and strongly felt ; it is one of the salient features of the man's
character, one of the determining influences of his life. Almost of
necessity it follows that it is imaginative in character ; that it does
not acquiesce in limitations which to another mind might seem in-
superable ; that it sees a way for itself, and foresees its satisfaction
with a clearness which gives to it perseverance and resolution. It
may be noble, but will not be too meek ; it may be wicked, but it
must not be petty ; it may be in fact, temporary, but no decay is
visible in it as yet. This strength of emotion seems to me the first
characteristic of romance. But by itself it is insufiicient for our
purpose. It must be taken in conjunction with the second.

All literature demands abstraction, just as any other inquiry does.
In romance abstraction is carried further than in writings where this
quality is not. Not merely is the vain attempt to show the whole
man and his whole life abandoned, but attention is directed in a
special degree to the one great emotion — or perhaps to two or three
great and conflicting emotions, whether all in the mind of one person
or assigned to the leading actors in the story. The small emotions
drop out or are minimised ; the infinite complication of motives is
avoided. This high degree of abstraction results in giving to the
chosen emotion a character of simplicity; it is cleared from the in-
trusion of rivals ; it is exhibited in possession of the field ; it is dis-
entangled from the afiairs of life ; or if the theme be a battle between
two great enemies, then the arena is cleared for their struggle, and
the small fry are kept out.

We may add another quality, which is really a resultant of this
union of strength and simplicity. The emotions of romance are
confident. As their strength causes them to make little of external
hindrances, as their simplicity frees them from being lost in the
entanglements of circumstances, so their confidence makes them not
self-questioning but self-asserting. They do not doubt themselves,
or impute unreality to themselves, or ask whether they are worth
having in the end, or whether the objects to which they are directed
are worth the trouble of winning. They are sure of themselves,
ready to give an account of themselves, finding in themselves their
own justification.

In these three qualities which I have tried to indicate are to be
found, I think, the leading characteristics of the emotions as they are
selected for and treated in writings of a romantic character. Anything
so definite as a definition is perhaps rather repugnant to the subject,
and certainly is, as it always is, dangerous to the speaker. In literary
matters to make a definition is — if you will allow me a professional
comparison — hardly less rash than to write a sequel ; both acts cause
the critical eye to glance towards the critical tomahawk. But I
think we shall not be very far wrong if at this stage we venture to

442 Mr. Anthony Hope Haiohins [May 7,

say that the aim of romance is to exhibit in action a strong, simple,
confident emotion, either in exclusive domination, or in conflict with
and ultimately triumphing over one or more emotions possessing the
same qualities, but proving in the end either less persistent or less
fortunate. No particular class of incidents is essential, no special
scenes, no special surroundings. Neither is any particular sort of
emotion essential : to take our old illustration, a sublime miserliness
might struggle with a keen parental affection, and a good romance
describe the conflict. But whatever the incidents, the scene or the
emotion, the qualities will remain. Some strong, simple and con-
fident emotion will dominate the persons, shape the events, and deter-
mine the character of the story. The task of incidents and scene is
simply to aiford a stage and to enhance the effectiveness of the drama.
Let me illustrate what I mean by a glance at one or two sorts of
novels which are not romances, l^emember, I am not saying that
they are not — or may not be — good novels, only that they have not
the marks of romance. I will take the emotion of Love — Love
between man and woman. This is treated in novels of all sorts, and
in many forms of literature besides ; that is due to its universality,
to the fact that it appeals to most writers and the certainty that it
will appeal to most readers. But it is a favourite of romance not
only for its universality, but even more because it lends itself most
readily to the characteristically romantic treatment. Above all other
emotions it is strong and resents control, it is simjile and rises above
circumstances, it is confident and self approved. But every novel
which deals with love is not romance. For example, there is a large
class of novels which give pictures of the life that is about us every
day, and in which love plays a part, perhaps, so far as the incidents
go, a leading part. But the love is not a subject, it is rather a datum,
it happens, it is not felt ; it occurs at a certain point because it is the
proper thing to occur, the natural feature of the young man's twenty-
fifth and the young lady's twentieth year, the suitable winding up of
the series of social sketches of which the novel consists, the suitable
recognition of what our national customs in regard to matrimony
happen to be. All this is not of necessity untrue to life, nor of
necessity uninteresting or unamusing or uninforming ; it may be
almost anything in the world except romance. We are told indeed
that Mr. A. and Mi-s B. are in love. Even so did Stage Managers in
old times stick up a board and write on it " This is Verona." Well,
we take your word for it, but otherwise it might as well have been
the Arctic regions. In this sort of book love is merely a premiss
from which we draw the conclusion — marriage — but what the emotion
of love itself is remains undiscussed, undescribed, to all appearance
uncomprehended. And it may be noticed that not a few of the
novels which have love for their theme, and are generally called, and
perhaps call themselves, romances, fail in this respect. The love-
making is itself mechanical ; it does not rule the book, and we are
forced to suspect the writer either of failing to understand his theme,

1897.] on Romance. 443

or of Laving confused his theme and his auxiliaries to such a point
that the passion which it is the real work of the book to exhibit
becomes no more than a subordinate and sometimes a tedious incident
in it. Why are these books not romances? It is because the
strength of the emotion is not realised or exhibited, there is no power,
no imagination. If any such love-affair, or rather marriage-arrange-
ment, as I have indicated, is to be found in a true romance of which
love is the theme, it is there, not for its own sake, but as an auxiliary,
useful by way of contrast, by its tameness heightening the effect of
the great emotion whose exhibition is the real purpose of the book.

Take another class of novels. I am in a difficulty about naming
it. If I say analytical, I confuse manner and matter ; if I say real-
istic, neither you nor I will be sure what I mean, and I shall probably
give a wrong impression. Perhaps I may take refuge in the semi-
slang phrase which came into vogue a little while ago, and speak of
the " problem novel." Problem novels are not romance ; the reason is
not the same as in the previous case ; there may be strength enough and
to spare in the emotions described. Nor is it because the emotion is
sometimes, as we say, illicit, being in conflict with law, or morality,
or convention ; there is in that nothing in the smallest degree incon-
sistent with romance — rather does romance find some of its finest
opportunities in situations so created. From the point of view of
romance, the fault here is the absence of simplicity and the resulting
want of confidence. The emotion is encumbered and complicated ; it
is surrounded by rivals ; it is tortured by problems social and ethical ;
it is mixed up with and obscured by questions of the relative duties,
the relative rights, the relative standards of men and women. Inter-
esting as all these questions are, they are not in the way of romance.
Or, again, the emotion is sapped from within ; it is hesitating, fearful,
doubtful ; it asks whether it really exists, or, if it exists, whether it
isn't something else than it seems to be, or if it really exists and really
is what it seems to be, then whether it has any business to exist, or
at any rate to be what it is ; or again, it does not know what it wants,
much less whether, if it wants it, it ought to want it, and so on.
There is no simplicity, no confidence ; in their place we find com-
plexity and self-distrust.

But of course it is not always so easy to draw the line, and even
though we assume every confidence in the formula we have adopted,
we should still be puzzled from time to time how we ought to class
a novel. We should not hesitate to call the ' Vicar of Wakefield ' a
romance, a true case of romance, notwithstanding its everyday charac-
ters and scenes. But take the great novels of manners — ' Tom Jones,'
or ' Vanity Fair,' or ' Pendennis.' In the broad sweep of books like
these there will be found matter of a romantic character, and we are
tempted to the easy course of some such division as one of pure
romances and mixed romances. But I fear that to adopt such a dis-
tinction would be rather a concession to mental indolence than an
obedience to the truth of the argument. We must ask again, What is

444 Mr. Anthony Rope Hawkins [May 7,

the theme ? and by that, when we have discovered it, we may judge.
We shall find, I think, that books like these are not romances, because
the romance that is in them is subordinate and subsidiary. Take
either ' Tom Jones ' or ' Pendennis,' and the theme seems to be (I
need not say that I speak with diffidence) something more varied and
something more complicated than romance deals with. We have the
picture of a young man, not only passing through a great variety of
incidents, but himself very variously, and often very temporarily,
affected by them. If you judge chapter by chapter you may say here
and there, " This is romance " ; but if you take the book as a whole
you will say, " No, there is not here the abstraction, the simplicity,
the concentration on two or three great emotions." There is abstrac-
tion, of course, but not in the high degree characteristic of romance ;
nor, again, has any one or any two emotions the pride of place which
romance assigns to them. You can hardly tie the writer down to any
narrower theme than " The Way of the World." The reason does
not lie in the number of characters or of incidents, although this is a
probable accompaniment of themes of such a nature. Take a novel,
or a series of novels, no less expausive in treatment, no less crowded
with incidents and characters — the story of D'Artagnan and the Mus-
keteers. We say at once, "Here is romance.' Why? As it seems
to me, because, in spite of all complexity, in spite of all deviations-,
in spite of the elaborate and minute tracing out of purely subsidiary
incidents, you have running through the whole book, inspiring it all
and exhibited in it all, one strong, simple, imperious passion or
emotion, which rules the lives of the leading characters and above all
of the great hero. Dumas' trilogy of the Musketeers is a romance of
the joy of action — of doing, of using hand and brain. These men do
not much mind what they are at, but they must be at something, and
this great desire of tlieirs despotically overrides every other emotion
and every consideration that endeavours to oppose it. They cannot
keep still ; they are in love with living. This temper of theirs—
again, above all, of D'Artagnan's — shapes and inspires the whole
book, so that kings and queens and cardinals, wars and plots and
amours, exist only as the stage on which it may exhibit itself, and as
the material from which it may satisfy its monstrous appetite for
joyful activity. I do not say that there is nothing of this temper in
* Tom Jones,' or even in ' Pendennis,' but it does not set the tone of
the book; it is not unimpeded, it is no more than an element. Would
it be possible to say, in a rough attempt at a summary, that the great
Englishmen use their heroes to illustrate the world, but that the great
Frenchman uses the world to satisfy and glorify his hero ?

But all writers of romance are not such as the creator of D'Artagnan
■ — I mean, of course, of D'Artagnan as we find him in the novels.
They cannot wring simplicity out of an almost limitless complication
of persons and incidents ; they cannot follow the thread through so
enormous and infinitely winding a maze. The result is one which
was foreshadowed by the fact that the ordinary man — ourselves at

189?.] on Romance. 445

ordinary minutes I mean — in his own mind identifies romance with
a particular framework of story or description of incident. We took
leave to call this a mistake, and we must call it one still, but now we
are in a position to see how it comes about. The presence or absence
of romance as the dominating character of the book is determined
fey the quality and treatment of the emotions exhibited in it. The
function of the incidents is to exhibit the emotions in action, and there
are certain classes of incidents which perform this office, if not more
perfectly than others, yet at all events more easily and more obviously.
Thus they tend to suggest themselves to the writer of romance ;
they are the line of least resistance along which his mind travels ;
thuy strike him at once as supplying the most effective stage for his
drama of emotion. Suppose, once more, that the passion of love is
the writer's theme. It is to be strong, persistent, not to be turned
aside. The readiest way to display these qualities is to confront it
with great obstacles, to demand of it great sacrifices and efforts, to
face the man who feels it with the peril of death. There may be
sacrifices as great as that of life, or greater ; but life is very obviously
a very great sacrifice, and appeals as such to everybody, even to those
who might miss the poignancy of some not less great but less obvious
act of self-devotion. Again, a mark of love is that it takes joy in
serving the object of love, and perhaps we may add, takes an especial
pride in the applause of the object of love. How better show this
mark of love, and thereby reinforce the impression of the love's
strength, than by causing the lover to preserve his mistress who in
her turn has come into great distress ? We see at once how fighting,
and perils, and all sorts of adventures, come to be so common in
romances as to have been mistaken for the essence of that of which they
are only accidental concdmitants, and to seem to be the theme where
they are only particularly handy and convenient auxiliaries ; for you
might reverse the parts and make the theme patriotism or courage,
using love as an auxiliaiy ; the same incidents would serve, only you
would have, so to say, to shift the centre of gravity ; or you might
have a struggle between the two, using still the same framework of
incident.

Again, from the point of view of the simplicity and confidence of
the emotion, it is naturally felt that these qualities are most readily
exhibited in hours of action, and are at their prime in moments of
strong excitement, such as arise in view of imminent danger or of
the necessity for rapid action. Thus it comes about that analysis
falls into the background, that the characters, being in fact reduced
to embodiments of one or two simple emotions which alone are of
service to the theme, require less detailed description, and that the
incidents acquire a greater relative importance and occupy more of
the writer's pen and of the reader's attention. And as a certain
startlingness in the incidents and a certain strangeness in the scene
afford a good stage for the emotions of the actor, so they predispose
the mind of the reader to sympathise with them, and, to use a common

446 Mr. Anthony Hope Hawkins [May 7,

phrase, to take them in the spirit in which they are meant. Their
remoteness from his everyday experience clears from his mind the
everyday atmosphere in which he lives, and persuades him into an
acquiescence in the justice of the picture ; he knows that, as a
general rule, he does not feel his emotions in just this form, but the
novelty and stirring nature of the incidents easily convince him that,
placed as the hero was, he would feel as the hero felt. In this way,
then, what are generally called romantic incidents and romantic sur-
roundings are of real assistance to romance in the proper sense ; they
both aid in the exhibition of the matter of the theme, and dispose the
reader to accept, approve and endorse it ; they harmonise with the
high pitch of the emotions shown in action, and afford a fit setting
for them. But it must be repeated that they are only one of many
settings, not better than others, but only more obvious, more ready,
and in fact more easy to handle. The writer propo-es to himself a less
difficult task than that which he would attempt if he dispensed with
these auxiliaries. Very much the same considerations are applicable
to what are called historical romances. Here again the strangeness
of scene, the remoteness from common experience, and the sense that
everyday criteria cannot be applied, help the reader to put himself at
the standpoint of the characters, and thus materially assist the writer
in his task. There is, in a word, less chance of the reader saying,
" I shouldn't feel like that, or act like that, and no more would he."

I have approached the borders of a question which I must not
wholly avoid. The romancer is often accused of dwelling in and of
inviting his readers to join him in an entirely artificial world, corre-
sponding to nothing in rerum natura, and of shirking that grappling
with the facts of life in which novelists of another school find their
hardest task and their highest glory. This charge of unreality is one
which romance must not shirk, but must face and analyse. I believe
myself that the accusation owes its origin in a great degree to the
same confusion of thought which has been already noted — to the idea
that the essence of romance is to be found in the incidents, rather
than in the emotions. For the emotions surely are not unreal ; they
are deep, fundamental, universal in human nature. But although
we must sturdily assert their reality, we may, without shame
and without hesitation, admit their rarity in the precise form
in which romance presents them. The " simple case " is, I take
it, always rare in nature; it has to be extracted; it is attained
as the result of a very high degree of abstraction. So it is in
literature ; and if all that is charged against the characteristic
themes of romance is that they are not often to be seen in undis-
turbed operation in life as we live it, the charge may be confessed.
But rarity is not falsity ; and not to happen very often, if it be a
fault, is a fault which affects many of the most important events in
the world's history. Abstraction is not the falsification of facts
ordinarily apparent, but rather the means of exhibiting truths ordi-
narily hidden — overlaid, as it were — by the multitude of circumstances

1897.] on Bomance. 447

and the compllcatioris of common feelings. Romance does not claim
to reflect all life, but certain aspects of life to which it gives pro-
minence. These are not the aspects with which the physician or
the statistician, or even the logician, is primarily concerned, but they
are true and important aspects. Eomance comes to be false only
when it allows itself to forget its own true nature and its own true
function. But for every form of literature the same penalty waits
on the same sin. What is called the realistic novel becomes false
when through an intemperate adoration of mere fact it forgets
that its business is with the minds of men, and that, given a certain
number of characters in the story, that only is essential which in
some way acts on the minds of those characters, and is, so to say, a
differentia of them as compared with the rest of the world ; what
they have for breakfast is of no matter unless it should give them
indigestion, and indigestion should i^roduce irritation or otherwise
affect the course of their thoughts and emotions. In like manner
romance becomes false when it forgets what its true theme is, lets
itself be carried away by the incidents, thinks only of them, and
instead of representing people influencing and being influenced by
events, gives us a series of mechanical stage effects happening to a
number of no less mechanical stage puppets. This sin is indeed
common ; perhaps no writer could show quite a clean sheet in regard
to it. But no cleverness, no inventiveness, no accomplishment in
mere technique, compensate for an error so fatal — ^just as no minute-
ness of observation or diligence in collecting what are called " docu-
ments," compensates for the corresponding sin of the writer whose
watchword is reality. In both sorts of books the thing in the end
is — the one thing in the end is, the temper of the characters. To
that we come back with a persistence only to be excused because
here lies the foundation of the whole matter. In romance the thing
is always the love of the woman, not the machinations of the villain
— the high mind of ambition, not the means it seeks or the prize
it aims at — the spirit of adventure, not the adventures — the joy in
action, not the precise actions by which the impulse seeks and finds
satisfaction. I have a notion that if we could know the order in
which the writer evolved his book, whether the man came first or
the incidents, whether he fitted his scene to his characters or con-
trived characters to put on his scene, we should in most cases be
able to say whether his book would be a good book or not a good
book in the most essential point. When a lady said to Sir Walter
Scott that she never knew what was going to happen on the next
page of his books. Sir Walter is reported to have replied, " Nor I
neither, madam." The story may well embody a truth ; he may
very likely not have known what was going to happen to his char-
acters, but depend upon it Sir Walter knew very well what was
happening and what was about to happen in them ; he knew where
he was going, though he might not have decided exactly what road
to take.

448 Mr. Anthony Hope Hawkins [May 7,

Perceiving this radical fact, we find all contradiction between
romance and the life we call real to vanish, and we must confess that
the fault has been in our own ideas and not in the subject with which
we are concerned. Romance becomes an expression of what are
perhaps the most important, the most far-reaching, the most deeply
•seated instincts and impulses of humanity. It has no monopoly of
this expression, but it is its privilege to render it in a singularly
clear, distiuct, and pure form ; it can give to Lwe an ideal object, to
anibition a boundless field, to courage a high occasion; and these
great emotions, revelling in their freedom, exhibit themselves in their
glory. Thus in its most worthy forms, in the hands of its masters,
it can not only delight men, but can touch them t ) the very heart.
It shows them wl.at they would be if they could, if time and fate and
circumstances did not bind, what in a sense they all are, and what
their acts would show them to be if an opportunity ofi'ered. So they
dream and are the happier, and at least none the worse, for their
dreams. It is the ^i^ of the Romancer, in the measure of his ability,
to see and reveal truths of the heart, and for a time to loose the
fetters that a man's own lot rivets on him, to bid men forget what is
round them, but not of them, about them, but not themselves. We
say that a man "forgets himself" in an exciting romance. We mean,
as we sometimes do in speaking, just the opposite of what we say. A
man does not read a good romance to forget himself, but to forget
what is not himself; and because he finds there something that
recalls the self which the changes and chances and troubles of the
world have almost made him forget, he is well pleased.

There are two points on which I wish to guard myself before I
sit down, if your patience will kindly allow me. The first has refer-
ence to what I have said about the relative position of incidents and
emotions. I must not be understood to mean anything in the least
like what is sometimes said, half-seriously, half-jokingly— that " the
plot doesn't matter." In my judgment the plot matters so much as
to be the surest mark of the writer's ability, and incomparably the
chief criterion of the merit of the book. But the word " plot " must
be understood in its proper sense, in the sense that makes it the very
core and kernel of the book, the story, the thing the writer tells the
reader. Every novel consists of emotions and incidents ; this is the
rudimentary analysis of it in respect of matter, just as the division
into theme and auxiliaries is the rudimentary analysis of it in respect
of form (I am not, of course, insisting on my own precise terms, but on
the obvious distinctions which I use them to express). The plot is
not emotions, for emotions idle, in a vacuum, so to speak, will yield no
story ; neither is it incidents, for as we saw at the beginning, naked
incidents, incidents without people and without emotions, will yield
no story. The j)lot of a romance is emotions and incidents — emotions
in action — and the merit of the plot lies first in choosing emotions of
true romantic quality, and secondly in fitting those emotions with
the most appropriate actions — those which will best exhibit the

1897.] on Romance. 449

emotions and most attract the reader to the engrossed study of them.
It is almost impossible to say, and certainly not very useful to spend
time in inquiring, whether the first task or the second is the more
difficult : the successful accomplishment of both is necessary to the
writing of a good romance, and the product which results from
bringing the emotions into contact with the incidents is the plot.
This product may or may not be in complete existence when the
writer begins the story ; it must be complete by the time he ends it.
I do not mean that every incident which may be related in a novel is
part of the plot, or every emotion which may be described either.
We may revert to the formal division of theme and auxiliaries, and
although it may not be practicable to draw a very definite line between
what belongs to the plot and what does not in all case^, we may say
that the plot lies in the theme and such of the auxiliaries as afford the
most immediate and essential vehicle for the expression of the theme.
Beyond these limits there may lie both many emotions and many in-
cidents, all of which should no doubt, if we are to follow a rigid rule,
have their particular service to perform in relation to the plot, but as
to which in the practice of critics considerable latitude is allowed,
2:)rovided that they are in themselves of an entertaining description,
or contain true and life-like sketches of human nature. No man is
denied a few digressions if he will make good use of the indulgence.

The second point is this. I may seem to have drifted into a
eulogy where I meant only to render justice, and to have claimed for
romantic novels a pre-eminence over other kinds. To make any such
pretentions on their behalf is not my purpose, and would by no means
represent my own opinion. The power and province of romance are
limited ; it cannot annex and does not seek to encroach upon sister-
kingdoms. Concerned itself with strong and simple emotions, it is
addressed to emotions of a similar nature ; it is primarily an appeal
to feeling, and to feeling of a direct, normal and straightforward
description. It is not armed with the keenest weapons of analysis;
it is not skilled to trace minute variations or to catch flitting shades ;
it is not at home with struggles and stirrings that find no outlet in
action, are invisible to the world, and barely conscious in the
heart which is their home ; it prefers an environment where a
man's individuality can have play, and has no pleasure in the
sombre picture of a tyranny of circumstances that crushes the actor
•into a mere sufferer; its purpose is not to arraign the equity of
institutions or to read the riddles of life. These subtle investiga-
tions, so attractive in their difficulty, so delicate and 25atient in
their methods, with their results so fascinating to the alert intellect
and the curious mind, it must leave to writings of another temper.
Nor, again, is it the way of romance to bid you stand by, an amused
spectator, while it exhibits to you scenes from the world's comedy,
and bids you laugh at follies of which you are not guilty, or at passions
from which you smilingly thank heaven you are free — or wonder you
are not ; it is not disinterested enough for that, and must have you

450 Mr. Anthony Hope Hawhins [May 7,

share the emotions which it displays before your eyes. It will make
terms with humour, but it does not love ridicule. In spite of the
deep truths with which romance deals, the romantic temper is, in a
sense, innocent, unsophisticated, primitive ; it throws itself into life
rather than analyses it ; it sympathises and shares, it does not stand
aloof and smile. Intricacy baffles it ; it retreats in fear from the bite
of the acid of irony. It is conversant with great sorrows, yet in the
end it is a cheerful thing. It trusts life, it loves life ; even for its
deepest woes there are the consolations of love or the hallowing pride
of memory — for when romance kills, she kills becomingly. It does
not ask whence we come and whither we go, it does not cry, " Vanity
of Vanities ! " But a temper like this, while it has its virtues, and
possesses about it much that is attractive, has its obvious limitations
and is subject to great disabilities. It is not a full expression of the
human mind ; it is not final, exhaustive, nor perhaps even particularly
heljpful in regard to the great problems which occupy the intellect ;
there are large fields of emotion which it leaves untouched, complica-
tions that it does not unravel, varieties that it cannot note, moods
with which it cannot enter into sympathy and which it seems rather
to delude than satisfy. So sometimes men and women turn away
from it in a sort of impatience, and they are especially apt to do this
when they are members of a society which is highly civilised, highly
cultivated, and much interested in the puzzles and difficulties that
beset the life of the community and the individual — a society that
takes a critical and perhaps not a very hopeful view of itself, that has
its intellect fully developed, its conscience very acute, and ( perhaps I
may add) its nervous system in a state of some irritation. Romance
seems then rather a childish thing — yes, like a child laughing in the
garden while a man lies dead in the house. Even if it were no more,
yet let the child laugh : his laughter is a part of the truth about the
world. But, as a matter of fact, this impatience may be understood
and excused as a mood, but is not to be justified as a criticism ; and
those who are guilty of it fail in catholicity of judgment. Because
romance cannot fill the place and discharge the function of other
writings inspired by difierent tempers and employing different means,
they are hasty to deny the value of its proper office and the import-
ance of the position it holds as one of the many forms which must be
assumed by that interpretation of human life which is the great oc-
cupation of all imaginative literature, and the title by which it com-
mands the attention of human minds. They are all at the task — the
careful chronicler, the keen analyst, the patient student, the smiling
comedian, the indignant satirist, the theoriser, the visionary, and the
wit. It is enough for the romancer to claim and take his place in
the rank, being sure that, if he pursues his own task faithfully and
performs it with ability, there are many who will find in him not the
worst companion, and few to whom he will not (at some moments,
at least) seem to speak words both of gladness and of truth. For
romance is, in the end, an assertion, constantly and confidently re-

1897.] on Romance. 451

peated, that, resistless as may seem the stream of tendencies, hard as
the fetters of fate, tyrannous as the order of society, of nature, or even
of the universe, yet there is still in men themselves an exuberant some-
thing which lives, and works, and does, and makes. Thus, after all
acknowledgment made of its limitations, with the amplest recognition
of the value and necessity to literature of other methods and other
points of view, it remains a fine expression of the vitality of the
human race, of the love of life and the fruitful joy in it, of the
excellent vigour of the spirit of man.

[A. H. H.]

WEEKLY EVENING MEETING,

Friday, May 14, 1897.

William Crookes, Esq. F.R.S. Vice-President, in the Chair.

Professor Harold Dixon, M.A. F.R.S.

Explosion-Flames.

The lecturer gave a brief history of the researches made on the
temperatures and pressures produced in explosion-flames, and ex-
hibited 'photographs of various explosion- flames taken on a very
rai)idly moving film. The photographs showed the movements of
the flame from the ignition point, and the effect of sound-waves
reflected from the ends of the explosion-tube.

452 Professeur Henri Moissan [May 28,

WEEKLY EVENING MEETING,

Friday May 28, 1897.

LiTDWiG MoND, Esq. Ph.D. F.R.S. Vice-President,
in the Chair.

Professeur Henri Moissan, Membra de I'Academie des Sciences,

Paris.

Le Fluor.

Milords, Mesdames et Messieurs, — J*ai ete heureux de repondre k
votre appel, et je tiens tout d'abord a vous remercier de I'honnenr
que vous avez bien voulu me faire en me demandant cette conference.

On connaissait depuis longtemps un mineral curieux auquel on a
donue le nom de fluorine et que Ton rencontre dans la nature en gros
cristaux cubiques, incolores ou teintes de vert ou de violet. Cette
fluorine est un compose binaire forme d'un metal, le calcium uni a un
autre corps simple qu'il avait ete impossible d'isoler jusqu'ici et
tiuquel on a donne le nom de fluor.

Ce fluorure de calcium a ete compare bien souvent au chlornre de
sodium dont les chimistes connaiseent parfaitement la composition.
En eflfet, entre les fluorures et les chlorures, il y a de grandes et
profondes analogies : le chlorure et le fluorure de potassium cristal-
lisent tons deux dans le systeme cubique. Les proprietes principales
des chlorures sent semblables a celles des fluorures. lis fournissent
le plus souvent des reactions paralleles ; traites par I'acide sulfurique
ils produisent les uns et les autres des acides hydrogenes solubles
dans I'eau et donnant a I'air d'abondantes fumees.

Outre le fluorure de calcium, on trouve encore, dans la nature,
d'autres composes renfermant du fluor. On connait, par exemple,
une combinaison complexe de phosphate de chaux et de fluorure de
calcium a laquelle on a donne le nom d'apatite.

Ce minerai, qui se presente parfois en tres jolis cristaux, a pu
etre obtenu synthetiquement dans les laboratoires, mais ce qui est
plus important, Henri Sainte-Claire Deville a pu preparer une apatite
chloree, et ce nouveau compose se presente en cristaux identiques a
ceux de I'apatite fluoree. On est dune en droit de dire que, dans ces
combinaisons le chlore pent remplacer le fluor, s'y substituer. C'est
la une analogic- remarquable, un lien qui reunissait le chlore bien
etudie, bien connu, a ce corps simple, non encore isole, le fluor.

Ai=je besoin de vous citre d'autres exemples ? lis ne nous man-

1897.] ! sur le Fluor. 453

querent pas. On connait la wagnerite, fluoree naturelle ; on peut
preparer le compose similaire chlore.

Ces analogies du chlore et dii fluor se ponrsuivent plus loin.

Traitons du sel marin, du chlorure de sodium, par de I'acide sul-
furique. Yous voyez qu'il se produit aussitot un abondant degage-
ment d'acide chlorhydrique gazeux.

Faisons de memo pour le fluorure de sodium. Ajoutons dans un
vase de plomb de I'acide sulfurique a un fluorure alcalin. J^ous
verrons des fumees intenses se produire. Dans I'un et I'autre cas,
nous aurons degage un corps gazeux a une temperature de + 20°
(centigrade), fumant abondamment a I'air, incolore, possedant les
caracteres d'un acide energique, s'unissant a I'etat anbydre avec
Tammoniaqiie, ties soluble dans I'eau et s'y combinant avec une
grande elevation de temperature.

Si nous donnons au fluorure de sodium, au compose binaire du
fluor et du sodium, la formule NaFl, celle du corps acide produit par
Taction de I'acide sulfurique ne peut etre que HFl. Les deux
reactions sent identiques,

Le corps gazeux, acide, produit dans cette reaction, est done une
combinaison de fluor et d'hydrogene, un corps analogue a I'acide
cblorbydrique auquel nous donnerons le nom d'acide fluorbydrique.

Mais, dans les sciences naturelles I'analogie ne suflit j)as ; la
metbode scientifique ne peut admettre que ce qui est rigoureusement
demontre. II fallait done tout d'abord prouver que I'acide fluorby-
drique etait un acide bydrogene. Et ceci, messieurs, va nous reporter
au commencement de ce siecle. Vous savez combien fut grande I'in-
fluence de Lavoisier sur I'essor de la cbimie en tant que science veri-
table. Vous savez combien ce grand esprit, par I'emploi contiuu de
la balance dans les reactions, fournit a la science que nous etudions une
rigueur matbematique. Frappe du role important de I'oxygene dans
la combustion, il crut que cet element etait indispensable a la forma-
tion des acides. Pour Lavoisier, tout acide etait un corps oxygeue ;
I'acide cblorbydrique fut done, d'apres les tb^ories de Lavoisier, con-
sidere comme renfermant de I'oxygene, et il en fut de mome, par
analogic, pour I'acide fluorbydrique.

C'est a votre grande savant Humpbry Davy que revient I'bonneur
d'avoir demontre que I'acide fluorbydrique ne renfermait pas d'oxy-
gene. Mais permettez-moi, avant d'arriver aux belles recbercbes de
Davy, de vous rappeler I'bistorique de la decouverte de I'acide fluor-
bydrique. Nous ne nous arreterons pas aux recbercbes de Margraff
Bur ce sujet, publiees en 1768, mais nous n'oublierons ]3as que ce fut
Scbeele qui caracterisa I'acide fluorbydrique en 1771, sans arriver
toutefois a I'obtenir a I'etat de purete. En 1809, Gay-Lussac et
Tbenard reprirent I'etude de cette preparation et arrivereut a pio-
duire un acide assez pur, tres concentre, mais qiii etait loin d'etre
anbydre. L'action de I'acide fluorbydrique sur la silice et les silicates
fut alors parfaitement elucidee.

Keportons-nous maintenant vers I'annee 1813, epoque oil Davy
Vol. XV. (No. 91.) 2 h

454 Professeur Eenri Moissan [May 28,

reprend I'etude de I'acide fluorhydrique. Peu de temps auparavant,
Ampere, dans deux lettres adressees a Humphry Davy, avait emis cette
opinion que I'acide fluorhydrique pouvait etre considere comme
forme par la combinaison de Fhydrogene avec un corps simple
encore inconnu, le fluor, en un mot que c'etait un acide non oxygene.

Davy, qui partageait cette idee, chercha done tout d'abord a
demontrer que I'acide fluorhydrique ne renferme pas d'oxygene. Pour
cela, il neutralise I'acide fluorhydrique par de I'ammoniaque et, en
chauffant fortement ce sel dans un appareil en platine, il ne recueille
dans la partie froide que le fluorhydrate d'ammoniaque sublime sans
aucune trace d'eau.

Repetons la meme experience, mais avec un acide oxygene ; pre-
nons de I'acide sulfurique que nous neutraliserons par de I'am-
moniaque ; nous obtenons ainsi du sulfate d'ammoniaque. Si nous
chauffons alors ce sel dans le meme appareil en platine, il fond vers
140°, puis vers 180° il se decompose en ammoniaque et en bisulfate,
enfin ce dernier sel se transforme par une nouvelle elevation de tem-
perature en bisulfite d'ammoniaque volatil, en azote et en eau.

Ainsi, en chauffant fortement le sulfate d'ammoniaque, il y a eu
formation d'eau. Et dans cette experience de Davy, lorsque I'on se
trouve en presence d'un acide oxygene, la quantite d'eau recueillie est
assez grande pour etre admise d'une fagon indiscutable. Le fluor-
hydrate d'ammoniaque, de meme que le chlorhydrate, ne fournissant
pas d'eau par sa decomposition, on etait done conduit a dire que I'acide
fluorhydrique ne renfermait pas d'oxygene et qu'il etait analogue a
I'acide chlorhydrique. Or, on sait par demonstration experimentale
que I'acide chlorhydrique est forme de chlore et d'hydrogene ; il est
done logique de penser que I'acide fluorhydrique est produit par la
combinaison de I'hydrogene avec le fluor.

Cette experience importante, faite par des mains exercees, ne
parvint cependant pas a faire admettre d'une fa^on generale, I'exis-
tence des hydracides.

Les idees de Lavoisier sur le role de I'oxygene dans la formation
des acides, idees qui avaient ete combattues au debut, etaient alors
si bien admises que beaucoup d'esprits se refusaient a croire a I'exis-
tence d'acides hydrogenes. Ce ne fut qu'apres les recherches memo-
rabies de Gay-Lussac sur le cyanogene et sur I'acide cyanhydrique,
qu'il fat deraontre d'une fa9on indiscutable qu'il pouvait exister des
acides energiques ne reufermant pas trace d'oxygene.

D'ailleurs, quand nous avons a comparer les combinaisons acides
formees par le chlore, par exemple, ou le soufre, avec I'hydrogene,
nous avons la deux types de composes tout a fait differents.

Prenons un volume de chlore et un volume d'hydrogene ; sous
Taction de la lumiere ou d'une etincelle d'induction, ils s'uniront
pour former deux volumes de gaz acide chlorhydrique, compose ayant
toutes les proprietes d'une acide tres energique.

Si nous combinons deux volumes d'hydrogene a un volume de
vapeur de soufre, nous obtiendrons deux volumes de gaz hydrogene

1897.] sur le FUor. 455

sulfure, possedant encore une reaction acide, il est vrai, mais incom-
parablement plus faible que celle de Tacide chlorhydrique.

II est bien evident que, par ses reactions energiques, par le
degagement de chaleur qu'il produit au contact de I'eau et des bases,
I'acide fluorbydrique doit etre compare a I'acide chlorhydrique et non
a I'acide sulfhydrique. II se rapproche absolument de cet acide
chlorhydrique forme d'un volume de chlore et d'un volume d'hydro-
gene unis sans condensation.

Permettez-moi maintenant de vous rappeler une experience
beaucoup plus recente de Gorre. Ce chimiste a chauffe du fluorure
d'argent dans une atmosphere d'hydrogene. II a vu, dans ces condi-
tions, le volume gazeux doubler ; il semble done bien que I'acide
fluorhydrique soit forme d'un volume d'hydrogene uni a un volume
de ce corps simple non encore isole, le fluor. De plus, c'est bien ce
meme corps simple qui a quitte le fluorure d'argent pour s'unir a
I'hydrogene et produire I'acide fluorhydrique dont nous venons de
parler precedemment.

Ainsi, messieurs, sans preparer ce fluor, sans pouvoir le separer
des corps avec lesquels il est uni, la chimie etait parvenue a etudier
et a analyser un grand nombre de ses combinaisons. Le corps n'etait
pas isole et cependant sa place etait marquee dans nos classifications.
Et c'est la ce qui nous demontre bien I'utilite d'une theorie scien-
tifique : theorie qui sera regardee comme vraie pendant un certain
temps, qui resumera les faits et permettra a I'esprit de nouvelles
hypotheses, causes premieres d'experiences, qui, pen a peu detruiront
cette meme theorie, pour la remplacer par une autre plus en harmonie
avec les progres de la science.

C'est ainsi que certaines proprietes du fluor etaient prevues avant
meme que son isolement ait ete possible.

Voyons maintenant quels ont ete les essais tentes, non seulement
sur cet acide fluorhydrique, mais encore sur les fluorures, pour arriver
a isoler le fluor.

Je vous parlais tout a I'heure des experiences de Davy, dans
lesquelles il a demontre notamment que I'acide fluorhydrique ne
renfermait pas d'oxygene. Outre ces experiences, Davy en a fait un
grand nombre d'autres que je rappellerai en les resumant.

On pent d'une fagon generale diviser les recherches entreprises sur
le fluor en deux grandes classes :

1°. Experiences faites par voie electrolytique s'adressant soit a
I'acide soit aux fluorures.

2°. Experiences faites par voie seche. Des le debut de ces
recherches, il etait a prevoir que le fluor decomposerait I'eau
quand on pourrait I'isoler ; par consequent, toutes les tentatives qui
ont ete faites par la voie humide depuis les premiers travaux de Davy
le furent sans aucune espece de chance de succes.

Humphry Davy a fait beaucoup d'experiences electriques, et ces ex-
periences il les a executees dans des appareils en platine ou en chlorure
d'argent fondu et au moyen de la puissante pile do la Societe royalu,

2 Ti 2

456 Professeur Henri Moissan [May 28,

II a reconnu que I'acide fluorhydrique se decomposait tant qu'il
contenait de I'eau et qu'ensuite le courant semblait passer avec beau-
coup plus de difficulte. II a essaye aussi de faire jaillir des etin-
celles dans I'acide concentre, et il a pu, dans quelques essais, obtenir
par cette metbode une petite quantite de gaz. Mais I'acide, bien que
refroidi, ne tardait pas a se reduire en vapeurs : le laboratoire devenait
rapidement inhabitable. Davy fut meme tres malade pour s'etre
expose a respirer les vapeurs d'acide fluorhydrique et il conseille aux
chimistes de prendre de grandes precautions pour eviter Taction de
cet acide sur la peau et sur les bronches. Vous savez, messieurs, que
Gay-Lussac et Thenard avaient eu egalement beaucoup a souffrir do
ces memos vapeurs acides.

Les autres experiences de Davy (je ne puis les citer toutes) ont
ete faites surtout en faisant reagir le cblore sur les fluorures. Elles
presentaient des difficultes tres grandes, car on ignorait a cette epoque
I'existence des fluorhydrates de fluorures et Ton ne savait point pre-
parer la plupart des fluorures anhydres.

Ces recherches de Davy sent, comme on pouvait s'y attendre, de la
plus haute importance, et une propriete remarquable du fluor a ete
mise en evidence par ce savant : dans les recherches oii il avait eto
possible de produire une petite quantite de ce radical des fluorures, le
platine ou I'or des vases dans lesquels se faisait la reaction etait pro-
fondement attaque. II s'etait forme dans ce cas des fluorures d'or ou
de platine.

Davy a varie beaucoup les conditions de ces experiences. II a
repete Taction du chlore sur un fluorure metallique dans des vases de
soufre, de charbon, d'or, de platine, etc. ; il n'est jamais arrive a un
resultat satisfaisant.

II est conduit aiusi a penser que le fluor possedera sans doute une
activite chimique beaucoup plus grande que celle des composes connus.

Et en terminant son niemoire Humphry Davy indique que ces
experiences pourraient peut-etre reussir si elles etaient executees dans
des vases en fluorine. Nous aliens voir que cette idee va etre reprise
par differents experimentateurs. La lecture du travail de Davy vous
interesse, vous caj)tive au plus haut point. Je ne puis mieux comparer
ce beau memoire qu'a ces tableaux de maitre auxquels le temps ajoute
un nouveau charme. On ne se lasse jamais de les admirer et Ton y
decouvre sans cesse de nouveaux details et de nouvelles beautes.

C'est en operant dans des appareils en fluorure de calcium que les
freres Knox essayerent de decomposer le fluorure d'argent par le
chlore. La principale objection a faire a leurs experiences repose
sur ce fait que le fluorure d'argent employe n'etait pas sec. II est en
eflet tres difficile de deshydrater completement les fluorures de
mercure et d'argent. De plus, nous verrons, par les recherches de
Fremy, que Taction du chlore sur les fluorures tend plutot a former
des produits d'addition, des fluochlorures, qu'a chasser le fluor et a le
mettre en liberte.

En 1848, Louyet en operant aussi dans des ajipareils en fluorine.

1897.] sur le Fluor. 457

etudia une reaction analogue : il fit reagir le chlore sur le fluorure do
mercure. Les objections que Ton peut faire aux recherches des freres
Knox s'appliquent aussi aux travaux de Louyet. Fremy a demontre
que le fluorure de mercure prepare par le precede de Louyet renfer-
mait encore une notable quantite d'eau. Aussi les resultats obtenus
etaient assez variables. Le gaz recueilli etait un melange d'air, de
chlore et d'acide fluorliydrique, dont les proprietes se modifiaient
suivant la duree de la preparation.

Les freres Knox se plaignirent beaucoup de Taction de I'acide
fluorhydrique sur les voies respiratoires, et, a la suite de leurs travaux
I'un d'eux rapporte qu'il a passe trois annees a Genes, et en est
revenu encore tres soufi"rant. Quant a Louyet, entraine par ses
recbercbes, il ne prit pas assez de precautions pour eviter Faction
irritante des vapours d'acide fluorbydrique, et il paya de sa vie son
devouement a la science.

Ces recbercbes de Louyet amenerent Fremy a reprendre vers
1850 cette question de I'isolement du fluor. Fremy etudia d'abord
avec metbode les fluorures metalliques; il demontra I'existence de
nombreux fluorbydrates de fluorures, indiqua leurs proprietes et leur
composition. Puis, il fit reagir un grand nombre de corps gazeux sur
ces diflerents fluorures ; Taction du cblore, de Toxygene fut etudiee
avec soin. Eufin, toute son attention fut attiree sur Telectrolyse des
fluorures metalliques.

La plupart de ces experiences etait faite dans des vases de platine
a des temperatures parfois tres elevees. Lorsque, apres cette etude
general des fluorures, Fremy reprit Taction du cblore sur les
fluorures de plomb, d'antimoine, de mercure et d'argent, il montra
nettement la presque impossibilite d'obtenir a cette epoque ces
fluorures absolument sees. Aussi Ton comprend que, dans ces
recbercbes electrolytiques, ce savant se soit adresse surtout au
fluorure de calcium.

Ayant vu combien les fluorures retiennent Teau avec avidite, il
revient toujours a, cette fluorine, qu'on trouve parfois dans la nature
dans un grand etat de purete, et absolument anbydre. C'est ce
fluorure de calcium maintenu liquide, grace a une baute temperature,
qu'il va electrolyser dans un vase de jDlatine.

Dans ces conditions, le metal calcium se porte au pole negatif, et
Ton voit, autour de la tige de platine qui constitue Telectrode nega-
tive et qui se ronge avec rapidite, un bouillonnement indiquant la
mise en liberte d'un nouveau corps gazeux.

Certainement, dans ces experiences, du fluor a ete mis en liberte,
mais, messieurs, representez-vous cette electrolyse faite a la tempera-
ture du rouge vif. Combien Texperience devient difficile dans ces
conditions ; comment recueillir le gaz ? comment en constater les
proprietes ? Ce corps gazeux deplace Tiode des iodures ; mais,
aussitot que Ton tente quelques essais, le metal alcalin, mis en
liberte, perce la parol de platine ; tout est a recommencer, Tappareil
est mis bors d'usage.

458 Trofesseur Henri Moissan [May 28,

Loin de se decourager par les insucces, Fremy apporte, au con-
traire, dans ces recherches, une perseverance incroyable. II varie
ses experiences, modifie ses appareils, et les difficultes ne font que
I'encourager a poursuivre son etude.

Deux faits importants se degagent tout d'abord de ses travaux :
I'un qui est entre immediatement dans le domaine de la science;
I'autre qui semble avoir frappe beaucoup moins les esprits.

Le premier c'est la preparation de I'acide fluorbydrique anbydre,
de I'acide fluorbydrique pur. Jusqu'aux recbercbes de Fremy, on
avait ignore I'existence de I'acide fluorbydrique vraiment prive d'eau.
Ayant prepare et analyse le fluorbydrate de fluorure de potassium,
Frcmy s'en sert aussitot pour obtenir I'acide fluorbydrique pur et
anbydre.

il prepare ainsi un corps gazeux a la temperature ordinaire qui se
condense dans un melange refrigerant en un liquide incolore tres
avide d'eau. Voila done une reaction d'une grande importance .
preparation de I'acide fluorbydrique pur.

Je tiens a vous faire remarquer en passant que le jour ou Hum-
pbry Davy a electrolyse I'acide fluorbydrique concentre, le liquide
mauvais conducteur qu'il obtenait a la fin de son experience etait de
I'acide fluorbydrique a pen pres anbydre.

Le second fait, qui a passe je dirai presque inaper9u et qui m'a
vivement interesse, surtout a la fin de mes recbercbes, c'est que le
fluor a la plus grande tendance a s'unir a presque tons les composes
par voie d'addition.

En un mot, le fluor forme avec facilite des composes ternaires et
quaternaires. Faisons reagir le cblore sur un fluorure ; au lieu
d'isoler le fluor, nous preparerons un fluocblorure. Employons
I'oxygene, nous ferons un oxyfluorure. Cette propriete nous ex-
plique I'insucces des essais de Louyet, des freres Knox et d'autres
operateurs. Memo en agissant sur les fluorures sees, dans une atmos-
pbere de cblore, de brome ou d'iode, nous aurons plutot des com-
poses ternaires que du fluor libre. Ce fait a ete nettement mis en
evidence par Fremy. Et le memoire de ce savant comportait un si
grand nombre d'experiences, qu'il semble avoir decourage les cbimis-
tes, ariete I'essor^de nouvelles tentatives. Depuis 1856, date de la
publication du memoire de M. Fremy, les recbercbes sur I'acide
fluorbydrique et sur I'isolement du fluor sont peu nombreuses. La
question parait subir un temps d'arret. Cependant, en 1869, M. Gorre
reprend avec metbode I'etude de I'acide fluorbydrique. II part de
I'acide fluorbydrique anbydre prepare par la metbode de Fremy ; il
determine son point d'ebuUition, sa tension de vapeur aux diff'erentes
temperatures, enfin ses principales proprietes. Son memoire est
d'une exactitude remarquable. Des nombreuses recbercbes de Gorre,
nous ne retiendrous pour le moment que les suivantes, sur lesquelies
je veux appeler votre attention.

Ce savant electrolyse dans un appareil special de I'acide fluor-
bydrique anbydre con tenant une petite quantite de fluorure de platine,

1897.] sur le Fluor. 459

de telle sorte qu'il puisse recueillir les gaz produits a chaque elec-
trode ; il voit au pole negatif se degager de I'hydrogene en abondance,
tandis que la tige qui terminait le pole positif etait rongee avec
rapidite. Ce pbenomene etait identique a celui obtenu par Fremy dans
I'electrolyse du fluorure de calcium. Gorre verifie ensuite cette
observation de Faraday, que I'acide fluorbydrique contenant de I'eau
laisse passer le courant, mais que I'acide fluorbydrique absolument
pur, bien anbydre, n'est nullement conducteur. Dans une de ses
experiences, Gorre essaye d'electrolyser de I'acide fluorbydrique qui,
par suite d'une impurete, etait bon conducteur, et voulant eviter
I'usure de I'electrode, il y substitue une baguette de cbarbon.

Ce cbarbon, il le prepare avec soin, en cbauffant dans un courant
d'bydrogene un bois dense, qui lui fournit une tige sonore, bonne
conductrice de I'electricite. L'appareil etant monte, il commence
I'experience ; aussitot une violente explosion se produit, les morceaux
de cbarbon sent brises et projetes aux extremites du laboratoire. Gorre
repete I'experience plusieurs fois ; le resultat est toujours le meme.
Nous pouvons aujourd'bui donner I'explication de ce pbenomene.

Le cbarbon qu'il preparait ainsi par distillation d'un bois tres dur
etait rempli d'bydrogene. Yous savez tons, messieurs, combien les gaz
se condensent avec facilite dans le cbarbon ; les belles experiences de
Melsens I'ont etabli d'une fa9on tres nette. Lorsque Ton electro-
lysait ensuite de I'acide fluorbydrique conducteur, en pla9ant au pole
positif un semblable cbarbon, il se degageait du fluor qui s'unit a
I'bydrogene, comme nous le verrons plus loin, en produisant une
violente detonation. Dans cette experience de Gorre une petite
quantite de fluor avait ete mise en liberte, et c'est a sa combinaison
avec I'bydrogene occlus dans le cbarbon que I'explosion etait due.

Et maintenant, messieurs, j'arrive aux experiences nouvelles dent
j'ai a vous entretenir.

Je suis parti dans ces recbercbes d'une idee precongue. Si
Ton suppose pour un instant que le cblore n'ait pas encore ete
isole, bien que nous sacbions preparer les cblorures de pbospbore et
d'autres composes similaires, il est de toute evidence que Ton augmen-
tera les cbances que Ton pent avoir d'isoler cet element en s'adressant
aux composes que le cblore pent former avec les metalloides.

II me semblait qu'on obtieudrait plutot du cblore, en essayant de
decomposer le pentacblorure de pbospbore ou I'acide cblorbydrique
qu'en s'adressant a I'electrolyge du cblorure de calcium ou d'un
cblorure alcalin.

Ne doit-il pas en etre de meme pour le fluor ?

Enfin le fluor etant, d'apres les recbercbes anterieures et parti-
culierement celles de Davy, un corps done d'afiinites tres energiques,
on devait pour pouvoir recueillir cet element, operer a des tempera-
tures aussi basses que possible.

Telles sont les idees generales qui nous ont amene a reprendre
d'une fagon systematique I'etude des combinaisons formes par le fluor
et les metalloides.

460 Professeur Henri Moissan [May 28,

Je me suls adresse tout d'abord au fluorure de silicium, et j'ai ete
frappe, des ces premieres recherches, de la grande stabilite de ce
compose. Sauf les metaux alcalins, qui, au rouge sombre, le dedou-
blent avec facilite, peu de corps agissent sur le fluorure de silicium.
II est facile de se rendre compte de cette propriete si Ton remarque
que sa formation est accompagnee d'un tres grand degagement de
cbaleur. M. Bertbelot a demontre depuis longtemps que les corps
composes sent d'autant plus stables qu'ils degagent plus de cbaleur au
moment de leur production.

J'estimais done, a tort ou a raison, avant memo d'avoir isole le
fluor, que, si Ton parvenait jamais a preparer ce corps simple, il
devait se combiner avec incandescence au silicium cristallise. Et
cbaque fois que, dans ces longues recbercbes j'esperais avoir mis du
fluor en liberte, je ne manquais pas d'essayer cette reaction; on verra
plus loin qu'elle m'a parfaitement reussi.

Apres ces premieres experiences sur le fluorure de silicium, j'ai
entrepris des recbercbes sur les composes du fluor et du pbospbore.

M. Tborpe a decouvert le compose PbFP un pentafluorure de
pbospbore ; j'ai prepare le compose PbFr et j'ai porte toute mon
attention sur les reactions'qui permettaient d'essayer un dedoublement.
J'ai fait cette experience a laquelle avait songe Humpbry Davy, de
faire briiler le trifluorure de pbospbore dans I'oxygene, et je me suis
aper9u qu'il n'y avait pas eu formation d'acide pbospborique et mise
en liberte du fluor, comme I'esperait le savant anglais, mais que le
trifluorure et I'oxygene s'etaient unis pour donner un nouveau corps
gazeux, I'oxyfluorure de pbospbore.

N'etait-ce pas la un nouvel exemple de cette facilite que possede
le fluor de fournir des produits d'addition ?

J'ai tente alors, mais inutilement, Taction de I'etincelle d'induc-
tion sur le trifluorure de pbospbore. Cependant le pentafluorure de
pbospbore decouvert par M. Tborpe a pu etre dedouble par de tres
fortes etincelles en trifluorure de pbospbore et fluor.

Cette experience etait faite dans une eprouvette de verre sur la
cuve a mercure ; vous pensez bien qu'immediatement, il se produisait
du fluorure de mercure et du fluorure de silicium. On ne pouvait
pas esperer dans ces conditions conserver le fluor, memo noye dans
un exces de pentafluorure. J'ai done songe a une autre reaction.

On savait, depuis les recbercbes de Fremy, que le fluorure de
platine, produit dans I'electrolyse des fluorures alcalins, se decom-
posait sous I'influence d'une temperature elevee. Ayant constate que
les fluorures de pbospbore sont facilement absorbes a cbaud par la
mousse de platine, avec production finale de pbospbure de platine,
nous avions pense que ce precede de preparation du fluorure de platine
permettrait d'isoler le fluor. En cbauffant peu d'abord, I'absorption
du fluorure de pbospbore, par exemple, donnerait un melange de
pbospbore et de fluorure de platine, et la quantite de ce dernier etant
assez grande, une elevation de temperature pourrait en degager le
fluor. Ces experiences et d'autres analogues ont ete tcntees dans les

1897.] siir le Fluor. 461

conditions les plus propres a en assurer le succes ; elles ont fourni
des resultats interessants, mais qui n'avaient pas une nettete suffi-
sante pour resoudre la question de I'isolement du fluor.

En memo temps que so poursuivaient les etudes prececlentes, je
preparais le trifluorure d'arsenic qui avait ete obtenu par Dumas dans
un grand etat de purete ; je determinais ses coustantes physiques
ainsi que quelques proprietes nouvelles, et j'apportais tons mes soins
a etudier Taction du couj-ant electrique sur ce compose.

Le fluorure d'arsenic, corps liquide a la temperature ordinaire,
compose binaire forme d'un corps solide, I'arsenic et d'un corps gazeux,
le fluor, semblait se preter dans d'excellentes conditions a des experi-
ences d'electrolyse.

J'ai du, a quatre reprises differents, interrompre ces recherches sur
le fluorure d'arsenic, dont le maniement est plus dangereux que celui
de I'acide fluorhydrique anhydre et dont les proprietes toxiques
m'avaient mis dans I'impossibilite de continuer ces experiences.

Je suis arrive cependant a electro! yser ce compose en employant
le courant produit par 90 elements Bunsen.

Dans ces conditions, le courant passe d'une fagon continue ; I'ar-
senic se depose a I'etat pulverulent au pole negatif, et Ton voit se
former sur I'electrode positive des bulles gazeuses qui montent dans
le liquide mais sent absorbees presque aussitot. Le fluor mis en liberie
est repris de suite par le trifluorure d'arsenic AsFP qui passe a
I'etat de pentafluorure AsFP. Cette experience, poursuivie pendant
longtemps, ne m'a pas donne le fluor ; mais elle m'a fourni de precieux
renseignements sur I'electrolyse des composes fluores liquides, et elle
m'a conduit a la decomposition de I'acide fluorhydrique anhydre.

Pour arriver a I'electrolyse de I'acide fluorhydrique, j'avais fait
faire un petit appareil que vous avez sous les yeux et qui est forme
d'un tube en U en platine portant sur chaque branche un tube ab-
ducteur place au-dessus du niveau du liquide.

Les deux ouvertures de ce tube en U devaient etre fermees par des
bouchons de liege imbibes au prealable de paraffine ainsi que nous
I'avions fait dans toutes nos experiences sur I'electrolyse du fluorure
d'arsenic.

Un fil de platine traversait chaque bouchon et etait mis en com-
munication avec une pile de cinquante elements Bunsen.

Nous avons prepare tout d'abord de I'acide fluorhydrique pur et
anhydre, et nous avons vu que ce liquide, ainsi que I'avait indique
Faraday et ensuite Gorre, ne conduisait nullement le courant.

L'experience a ete variee de bien des fa9ons, le resultat est tou-
jours le memo. Avec le courant fourni par 90 elements Bunsen, la
decomposition ne se produit que lorsqu'on s'adresse a un acide hydrate,
et cette decomposition s'arrete aussitot que toute I'eau a ete separee
en hydrogene et oxygene. II semble done impossible d'obtenir, par
ce precede, le dedoublement de I'acide fluorhydrique en ses elements :
hydrogene et fluor.

Je me suis souvenu a ce moment, que, dans les etudes precedentes

462 Professeur Henri Moissan [May 28,

sur le fluorure d'arsenic, j'avais essaye de rendre ce liquide bon
conducteur, en radditionnant d'une petite quantite de fluorure de
manganese ou de fluorhydrate de fluorure de potassium. Ce precede
fut applique a I'acide fluorhydrique, et c'est alors qu'apres trois
annees de reclierclies, j'arrivai a la premiere experience importante sur
I'isolement du flu or.

L'acide fluorhydrique contenant du fluorhydrate de fluorure de
potassium se decompose sous Taction du courant et, dans I'appareil
que vous avez sous les yeux, on pent obtenir au pole negatif un
degagement regulier de gaz hydrogene. Qu'obtient-on au pole positif ?
Eien. Une legere augmentation de pression, voila tout. Seulement, en
demontant I'appareil, on remarque que le bouchon de liege du pole
positif a ete brule, carbonise, sur une pi'ofondcur d'un centimetre. Le
bouchon de liege paraffine du pole negatif n'a pas ete altere. II s'est
done degage au pole positif un corps agissant sur le liege avec une
activite toute differente de celle de l'acide fluorhydrique.

Je dois aj outer qu'afin de diminuer la tension de vapeur de l'acide
fluorhydrique, nous avons refroidi ce liquide dans nos experiences
au moyen du chlorure de methyle, qui, par une rapide evaporation,
nous produit un froid de — 50° (centigrade).

11 a fallu modifier I'appareil et particulierement la fermeture du
tube en U. Les bouchons en fluorine a frottement doux ne m'ont pas
donne de bons resultats. La gomme laque ou la gutta-percha dont
on les entourait etait rapidement attaque par le corps gazeux pro-
duit au pole positif. On dut alors recourir a une fermeture gazeuse,
au moyen de pas de vis en platine, et voici apres bien tatonnements,
comment I'experience fut disposee.

Le tube en U en platine est ferme par des bouchons a vis. Chacun
de ces bouchons est forme par un cylindre de spath-fluor, bien serti
dans un cylindre creux de platine, dont I'exterieur porte le pas de vis.
Chaque bouchon de fluorine laisse passer en son axe une tige carree
de platine. Ces tiges, plongeant par leur extremite inferieure dans
le liquide, servaient d'electrodes. Enfin, deux ajutages en platine
sondes a chaque branche du tube, au-dessous des bouchons, par con-
sequent au-dessus du niveau du liquide, permettaient aux gaz degages
par Taction du courant de s'echapper au dehors.

Pour obtenir l'acide fluorhydrique pur et anhydre on commence
par preparer le fluorhydrate de fluorure de potassium en prenant
toutes les precautions indiquees par Fremy. Lorsqu'on a obtenu ce
sel pur, on le desseche au bain-marie a 100°, et la capsule qui le con-
tient est placee ensuite dans le vide en presence d'acide sulfurique
concentre et de potasse fondue au creuset d'argent. L'acide et le
potasse sent remplaces tous les matins pendant quinze jours et le
vide est toujours maintenu dans les cloches a 1 centim. de mercure
environ.

II faut avoir soin pendant cette dessiccation, de pulveriser le sel de
temps en temps dans un mortier de fer, afin de renouveler les surfaces ;
lorsque le fluorhydrate ne contient plus d'eau, il tombe en poussiere

1897.] surle Fluor. 463^

et peut alors servir a preparer I'acide fliiorhydrique. II est a remarquer
que le fluorliydrate de fluorure de potassium bien prepare est beaucoup
moins deliquescent que le fluorure.

Lorsque le fluorhydrate est bien sec, il est introduit rapidement
dans un alambic en platine que Ton a seche en le portant au rouge
pen de temps auparavant. On le maintient a une douce temperature
pendant une heure ou une heure et demie de fagon que la decomposi-
tion commence tres lentement ; on perd la premiere portion d'acide
fluorhydrique forme qui entraine avec elle les petites traces d'eau
pouvant rester dans le sel. Le recipient de platine est alors adapte a
la cornue et Ton chauffe plus fortement, tout en conduisant la decom-
position du fluorhydrate avec une certaine lenteur. On entoure en-
suite ce recipient d'un melange de glace et de sel, et a partir de ce
moment, tout I'acide fluorliydrique est condense et fournit un liquide
limpide, bouillant a 19° '5, tres hygroscopique et produisant, comme
Ton sait, d'abondantes fumees en presence de I'humidite de Fair.

Pendant cette operation, le tube en U en platine, dessecbe avec le
plus grand soin, a ete fixe au moyen d'un bouchon dans un vase de
verre cyliudrique et entoure de cblorure de methyle. Jusqu'au
moment de I'introduction de I'acide fluorbydrique, les tubes abduc-
teurs sont relies a des eprouvettes dessecbantes contenant de la potasse
fondue. Pour faire penetrer I'acide fluorbydrique dans ce petit appareil,
on peut I'absorber par Tun des tubes lateraux dans le recipient meme
GUI il s'est condense.

Lorsqu'on a fait penetrer, a I'avance, un volume determine d'acide
fluorbydrique liquide dans le petit appareil en platine, refroidi par le
cblorure de methyle en ebullition tranquille, a la temperature de
— 23°, on fait passer dans les electrodes le courant produit par 25
elements Bunsen, grand modele, montes en serie. Un ampere-
metre, place dans le circuit, permet de se rendre compte de I'intensite
du courant.

Afin de rendre I'acide conducteur, nous y avons ajoute, avant
I'experience, une petite quantite de fluorhydrate de fluorure de
potassium seche et fondu ; environ 2 grammes pour 10 centimetres
cubes d'acide. Dans ce cas, la decomposition se produit d'une fagon
continue, et Ton obtient, au pole negatif, un gaz brulant avec une
flamme incolore et presentant tons les caracteres de I'hydrogene ; au
pole positif, un gaz incolore d'une odeur penetrante tres desagreable,
se rapprochant de celle de I'acide hypochloreux, et irritant rapide-
ment la muqueuse de la gorge et les yeux. Nous faisons en ce
moment I'experience sous vos yeux. Le nouveau corps gazeux est done
de proprietes tres energiques : vous voyez le soufre s'enflammer a
son contact.

Le phosphore prend feu et fournit un melange d'oxyfluorure et de
fluorure de phosphore. L'iode s'y combine avec une flamme pale en
perdant sa couleur. L'arsenic et I'antimoine en poudre se com-
binent au fluor avec incandescence.

Le silicium cristallise, froid, brule de suite au contact de ce gaz

464 Professeur Henri Moissan [May 28,

avec beaucoup d'eclat. Parfois il se produit des etincelles ; il se
forme du fluorure de silicium qui a ete recueilli sur le inercure et
nettement caracterise.

Le bore pur brule egalement en se transformant en fluorure de
bore. Le carbone amorpbe devient incandescent au contact du fluor.
Pour faire ces differentes experiences, il suffit de placer, comme vous
le vojez, les corps solides dans un petit tube de verre et de les
approclier de I'extremite du tube de platine par lequel se degage le
fluor. On pent aussi repeter ces experiences en mettant de petits
fragments des corps solides a etudier sur le couvercle d'un creuset
de platine maintenu aupres de I'ouverture du tube abducteur.

Ce gaz decompose I'eau a froid en fournissant de I'acide fluor-
hydrique et de I'ozone; il enflamme le sulfure de carbone et, re-
cueilli dans une capsule de platine remplie de tetrachlorure de
carbone, il fournit un degagemeut continu de chlore.

Le chlorure de potassium fondu est attaque a froid, avec degage-
ment de chlore. En presence du mercure, I'absorption est complete
avec formation de protofluorure de mercure de couleur jaune clair.
Le potassium et le sodium deviennent incandescents et fournissent
des fluorures. D'une fagon generale, les metaux sent attaques avec
beaucoup moins d'energie que les metalloides. Cela tient, pensons-
nous, a ce que la petite quantite de fluorure metallique forme empeobe
I'attaque d'etre profonde. Le fer et le manganese en poudre brulent
en fournissant des etincelles.

Les corps organiques sent violemment attaques. Un morceau de
liege, place aupres de I'extremite du tube de platine par lequel le gaz
se degage, se carbonise aussitot et s'enflamme. L'alcool, I'ether, la
benzine, I'essence de terebenthine, le petrole prennent feu a son
contact.

En operant dans de bonnes conditions on peut obtenir a cbaque
pole un rendement de 2 litres a 4 litres de gaz par heure.

Lorsque I'experience a dure plusieurs beures et que la quantite
d'acide fluorhydrique liquide restant au fond du tube n'est plus
suffisante pour separer les deux gaz, ils se recombinent a froid dans
I'appareil en platine, avec une violente detonation.

Nous nous sommes assures par des experiences directes, faites au
moyen d'ozone sature d'acide fluorhydrique, qu'un semblable melange
ne produit aucune des reactions decrites precedemment. 11 en est de
meme de I'acide fluorhydrique gazeux. Nous ajouterons que I'acide
fluorhydrique employe ainsi que le fluorhydrate de fluorure etaient
absolument exempts de chlore. Enfin, on ne peut pas objector que le
nouveau gaz produit soit un perfluorure d'hydrogene ; car en presence
de fer chauffe au rouge maintenu dans un tube de platine, il est
absorbe entierement sans degagement d'hydrogene.

Enfin, dans des recherches plus recentes je me suis assure qu'il est
possible de faire ces experiences dans un appareil de cuivre tel que
celui que vous avez devant vous.

Par I'electrolyse de I'acide fluorhydrique rendu conducteur au

1897.] surle Fluor. 465

moyen de fluorhydrate de fluorure de potassium, on obtlent done au
pole negatif de I'liydrogene et au pole positif un degagement continu
d'un corps gazeux presentant des proprietes nouvelles, done d'affinites
tres energiques : ce corps gazeux est le jfluor.

Nous avons pu en determiner la densite, la couleur, le spectre,
etudier son action siir les corps simples et composes.

Maintenant que Ton connait les priucipales proprietes du fluor,
maintenant que cet element a pu etre isole, je suis convaincu que Ton
trouvera, malgre I'energie de ses reactions, de nouvelles methodes de
preparation.

II est a croire que Ton arrivera a preparer le fluor par un pro-
cede chimique fournissant de meilleurs rendements que le precede
electrolytique.

Le fluor aura-t-il jamais des applications ?

II est bien difficile de repondre a cette question, D'ailleurs, je
puis le dire en toute sincerite, je n'y pensais guere au moment ou j'ai
entrej)ris ces recherclies, et je crois que tous les chimistes qui ont
tente ces experiences avant moi n'y pensaient i)as davantage.

Une reclierclie scientifique est une recherche de la verite, et ce
n'est qu'apres cette premiere decouverte que les idees d'ajjplication
peuvent se produire avec utilite.

II est evident que lorsqu'on voit les grandes transformations
industrielles qui se font aujourd'hui sous nos yeux, on ne pent
se prononcer sur cette question. Apres la preparation de I'acier
Bessemer, la fabrication du manganese au haut fourneau, la produc-
tion de I'alizarine de synthese, le chimiste hesite toujours a nier la
vitalite industrielle d'une reaction de laboratoire.

Quand on pense a la valeur qu'avaient certains metaux tels que
le potassium et le sodium, lorsque Davy les preparait par elec-
trolyse ; quand on se rappelle que, par le procede de Gay-Lussac
et Thenard, ils revenaient a quelques milliers de francs le kilo-
gramme, et qu'aujourd'hui par les methodes electrolytiques ils ne
coutent plus que 5 francs, on n'ose plus dire qu'une reaction chimique
ne saurait avoir d'applications industrielles.

Seulement, messieurs, et c'est par la que je termine, il est curieux
de voir combien il faut d'efforts continus, de vues difiereutes, pour
arriver a resoudre une de ces questions scientifiques ; je devrais
dire plutot pour faire progresser une de ces questions seientifiques, car
en realite un sujet n'est jamais forme. II reste toujours ouvert pour
nos successeurs : nous ne faisons qu'ajouter un anneau a une chaine
sans fin.

L'avancement de la science est lent ; il ne se produit qu'a force
de travail et de tenacite. Et lorsqu'on est arrive a un resultat, ne
doit-on pas par reconnaissance se reporter aux efforts do ceux qui
vous ont precedes, de ceux qui ont lutte et peine avant vous? N'est-ce
pas en eflet un devoir de rappeler les difficultes qu'ils ont vaiucues,
les vues qui les ont diriges et comment des hommes, differents de pays
et d'idees, de position, et de caractere, mus seulement par I'amour de

466 Professeur Henri Moissan siir le Fluor. [May 28,

la science, se sont legues sans se connaitre la question inachevee;
afin qu'un dernier venu put recueillir les recherches de ses devan-
ciers et j ajouter a son tour, sa part d'intelligence et de travail?
Collaboration intellectuelle entierement consacree a la recherche de
la verite et qui se poursuit ainsi de siecle en siecle.

Ce patrimoine scientifique que nous cherchons toujours a etendre
est une partie de la fortune de I'humanite ; nous devons garder un
souvenir reconnaissant a tons ceux qui lui ont donne la chaleur de
leur coeur et le meilleur de leur esprit.

[H. M.]

1897.] Signalling through Space ivithout Wires. 467

WEEKLY EVENING MEETING,

Friday, June 4, 1897.

Sir Fbederick Bramwell, Bart. D.C.L. LL.D. F.R.S.
Honorary Secretary and Vice-President, in the Chair.

W. H. Preece, Esq. C.B. F.R.S. M. Inst. C.E.

Signalling through Space without Wires.

Science has conferred one great benefit on mankind. It has sup-
plied us with a new sense. We can now see the invisible, hear the
inaudible, and feel the intangible. We know that the universe is
filled with a homogeneous continuous elastic medium which transmits
heat, light, electricity and other forms of energy from one point of
space to another without loss. The discovery of the real existence
of this " ether " is one of the great scientific events of the Victorian
era. Its character and mechanism are not yet known by us. All
attempts to " invent " a perfect ether have proved beyond the mental
powers of the highest intellects. We can only say with Lord Salis-
bury that the ether is the nominative case to the verb " to undulate."
We must be content with a knowledge of the fact that it was created
in the beginning for the transmission of energy in all its forms,
that it transmits these energies in definite waves and with a known
velocity, that it is perfect of its kind, but that it still remains as
inscrutable as gravity or life itself.

Any disturbance of the ether must originate with some disturb-
ance of matter. An explosion, cyclone or vibratory motion may
occur in the photosphere of the sun. A disturbance or wave is im-
pressed on the ether. It is propagated in straight lines through
space. It falls on Jupiter, Venus, the Earth and every otlier planet
met with in its course, and any machine, human or mechanical,
capable of responding to its undulations indicates its presence. Thus
the eye supplies the sensation of light, the skin is sensitive to heat,
the galvanometer indicates electricity, the magnetometer indicates
disturbances in the earth's magnetic field. One of the greatest
scientific achievements of our generation is the magnificent generali-
sation of Clerk-Maxwell that all these disturbances are of precisely
the same kind, and that they differ only in degree. Light is an
electromagnetic phenomenon, and electricity in its progress through
space follows the laws of optics. Hertz proved this experimentally,
and few of us who heard it will forget the admirable lecture on

468 Mr. W. H. Preece [June 4,

" The Work of Hertz " given in this hall by Prof. Oliver Lodge
three years ago.*

By the kindness of Prof. Silvanus Thompson I am able to illus-
trate wave transmission by a very beautiful apparatus devised by
him. At one end we have the transmitter or oscillator, which is a
heavy suspended mass to which a blow or impulse is given, and
which, in consequence, vibrates a given number of times per minute.
At the other end is the receiver, or resonator, timed to vibrate to
the same period. Connecting the two together is a row of leaden
balls suspended so that each ball gives a portion of its energy at
each oscillation to the next in the series. Each ball vibrates at right
angles to or athwart the line of propagation of the wave, and as they
vibrate in different phases you will see that a wave is transmitted
from the transmitter to the receiver. The receiver takes up these
vibrations and responds in sympathy with the transmitter. Here we
have a visible illustration of that which is absolutely invisible. The
wave you see differs from a wave of light or of electricity only in its
length or in its frequency. Electric waves vary from units per
second in long submarine cables to millions per second when excited
by Hertz's method. laght- waves vary per second between 400 billions
in the red to 800 billions in the violet, and electric waves differ
from them in no other respect. They are reflected, refracted and
polarised, they are subject to interference, and they move through
the ether in straight lines with the same velocity, viz. 186,400 miles
per second — a number easily recalled when we remember that it was
in the year 1864 that Maxw^ell made his famous discovery of the
identity of light and electric waves.

Electric waves, however, differ from light waves in this, that we
have also to regard the direction at right angles to the line of pro-
pagation of the wave. The model gives an illustration of that which
happens along a line of electric force, the other line of motion I speak
of is a circle around the point of disturbance, and these lines are
called lines of magnetic force.\ The animal eye is tuned to one
series of waves, the " electric eye," as Lord Kelvin called Hertz's
resonator, to another. If electric waves could be reduced in
length to the forty- thousandth of an inch we should see them as
colours.

One more definition, and our ground is cleared. When elec-
tricity is found stored up in a potential state in the molecules of a
dielectric like air, glass or gutta-percha, the molecules are strained,
it is called a charge, and it establishes in its neighbourhood an electric
field. When it is active, or in its kinetic state in a circuit, it is
called a current. It is found in both states, kinetic and potential,
when a current is maintained in a conductor. The surrounding

* This is published in an enlarged and useful form by ' The Electrician '
Printing and Publishing Company. — W. H. P.
t Vide Fig. 4, p. 474.

1897.] on Signalling through Space without Wires. 469

neighbourhood is tben fouud in a state of stress forming what is
called a magnetic field.

In the tirst case the charges can be made to rise and fall, and to
surge to and fro with rhythmic regularity, exciting electric icaves
along each line of electric force at very high frequencies, and
in the second case the currents can rise or alternate in direction
with the same regularity — but with very diiferent frequencies — and
originate electromagnetic waves whose wave fronts are propagated in
the same direction.

The first is the method of Hertz, which has recently been turned
to practical account by Mr. Marconi, and the second is the method
which I have been applying, and which for historical reasons I will
describe to you first.

In 1884 messages sent through insulated wires buried in iron
pipes in the streets of London were read upon telephone circuits
erected on poles above the housetops, 80 feet away. Ordinary tele-
graph circuits were found in 1885 to produce disturbances 2000 feet
away. Distinct speech by telephone was carried on through one
quarter of a mile, a distance that was increased to 1 j mile at a later
date. Careful experiments were made in 1886 and 1887 to prove
that those ejects were due to pure electromagnetic waves, and were
entirely free from any earth-conduction. In 1892 distinct messages
were sent across a portion of the Bristol Channel between Penarth
and Flat Holm, a distance of 3 • 3 miles.

Early in 1895 the cable between Oban and the Isle of Mull broke
down, and as no ship was available for repairing and restoring com-
munication, communication was established by utilising parallel wires
on each side of the channel and transmitting signals across this
space by these electromacjnetic waves.

The apparatus (Fig. 1) connected to each wire consists of —

(a) A rheotome or make and break wheel, causing about 260
undulations per second in the primary wire.

(h) An ordinary battery of about 100 Leclanche cells, of the
so-called dry and portable form.

(c) A Morse telegraph key.

(d) A telephone to act as receiver.

(e) A switch to start and stop the rheotome.

Good signals depend more on the rapid rise and fall of the
primary current than on the amount of energy thrown into vibration.
Leclanche cells give as good signals at 3*3 miles distant as 2 J H.P.
transformed into alternating currents by an alternator, owing to the
smooth sinusoidal curves of the latter. 260 vibrations per second
give a pleasant note to the ear, easily read when broken up by the
key into dots and dashes.

In my electromagnetic system two parallel circuits are estab-
lished, one on each side of a channel or bank of a river, each circuit
becoming successively the primary and secondary ot an induction
system, according to the direction in which the signals are being

Vol. XV. (No. 91.) 2 i

470

Mr. W. E. Preece

[June 4,

sent. Strong alternating or vibrating currents of electricity are
transmitted in the first circuit so as to form signals, letters and
words in Morse character. The effects of the rise and fall of these
currents are transmitted as electromagnetic waves through the inter-
vening space, and if the secondary circuit is so situated as to be
washed by these ethereal waves, their energy is transformed into
secondary currents in the second circuit which can be made to affect
a telephone and thus to reproduce the signals. Of course their
intensity is much reduced, but still their presence has been detected
though five miles of clear space have separated the two circuits.

Such effects have been known scientifically in the laboratory
since the days of Faraday and of Henry, but it is only within the

CURRENT BREAKER

Fig. 1 — Diagram of connections of Mr. Preece's system.

last few years that I have been able to utilise them practically
through considerable distances. This has been rendered possible
through the introduction of the telephone.

Last year (August, 1896) an effort was made to establish com-
munication with the North Sandhead (Goodwin) lightship. The
apparatus used was designed and manufactured by Messrs. Evershed
and Vignoles, and a most ingenious relay to establish a call was in-
vented by Mr. Evershed. One extremity of the cable was coiled in a
ring on the bottom of the sea, embracing the whole area over which
the lightship swept while swinging to the tide, and the other end was
connected with the shore. The ship was surrounded above the
water line with another coil. The two coils were separated by a
mean distance of about 200 fathoms, but communication was found
to be impracticable. The screening effect of the sea water and the
effect of the iron hull of the ship absorbed practically all the energy

1897.

on Signalling through Space without Wires.

471

r-4-

i c

^— WW-

of tbe currents in the coiled cable, and the effects on board, though
perceptible, were very trifling — too minute for signalling. Previous
experiments had failed to show the extremely rapid rate at which
energy is absorbed with the depth or thickness of sea water. The
energy is absorbed in forming eddy currents. There is no difficulty
whatever in signalling through 15 fathoms. Speech by telephone
has been maintained tiirough 6 fathoms. Although this experiment
has failed through water, it is thoroughly practical through air to
considerable distances where it is possible to erect wires of similar
length to the distance to be crossed on each side of the channel. It
is not always possible, however, to do this, nor to got the requi-
site height to secure the best effect. It is impossible on a light-
ship and on rock lighthouses. There are many small islands —
Sark, for example — where it can-
not be done.

In July last Mr. Marc(mi
brought to England a new plan.
My plan is based entirely on
utilising electromagnetic waves
of very low frequency. It de-
pends essentially on the rise and
fall of currents in the primary
wire. Mr. Marconi utilises elec-
tric or Hertzian waves of very
high frequency, and they depend
upon the rise and fall of electric
force in a sphere or spheres. He
has invented a new relay which,
for sensitiveness and delicacy, ex-
ceels all known electrical appa-
ratus.

The peculiarity of Mr. Mar-
coni's system is that, apart from
the ordinary connecting wires of
the apparatus, conductors of very
moderate length only are needed,
and even these can be dispensed
with if reflectors are used.

The Transmitter. — His trans-
mitter is Prof. Righi's form of
Hertz's radiator (Fig. 2).

Two spheres of solid brass, 4 inches in diameter (A and B), are
fixed in an oil-tight case D of insulating material, so that a hemisphere
of each is exposed, the other hemisphere being immersed in a bath
of vaseline oil. The use of oil has several advantages. It main-
tains the surfaces of the spheres electrically clean, avoiding the
frequent polishing required by Hertz's exposed balls. It impresses
on the waves excited by these spheres a uniform and constant form.

2 I 2

Fig. 2. — Dingrara of tbe Marconi
apparatus.

472 Mr. W. H. Preece [June 4,

It tends to reduce the wave lengths — Righi's waves are measured in
centimetres, while Hertz's were measured in metres. For these
reasons the distance at which effects are produced is increased.
Mr. Marconi uses generally waves of about 120 centimetres long. Two
small spheres, a and b, are fixed close to the large spheres, and con-
nected each to one end of the secondary circuit of the " induction
coil " C, the primary circuit of which is excited by a battery E,
thrown in and out of circuit by the Morse key K. Now, whenever the
key K is depressed sparks pass between 1, 2 and 3, and since the
system A B contains capacity and electric inertia, oscillations are set
up in it of extreme rapidity. The line of propagation is D d, and the
frequency of oscillation is probably about 250 millions per second.

The distance at which effects are produced with such rapid
oscillations depends chiefly on the energy in the discharge that passes.
A 6-inch spark coil has sufficed through 1, 2, 3, up to four miles,
but for greater distances we have used a more powerful coil — one
emitting sparks 20 inches long. It may also be pointed out that this
distance increases with the diameter of the spheres A and B, and it
is nearly doubled by making the spheres solid instead of hollow.

The Receiver. — Marconi's relay (Fig. 2) consists of a small glass
tube four centimetres long, into which two silver pole-pieces are
tightly fitted, separated from each other by about half a millimetre

a thin space which is filled up by a mixture of fine nickel and

silver filings, mixed with a trace of mercury. The tube is exhausted
to a vacuum of 4 mm., and sealed. It forms part of a circuit
containing a local cell and a sensitive telegraph relay. In its
normal condition the metallic powder is virtually an insulator.
The particles lie higgledy-piggledy, anyhow in disorder. They
lightly touch each other in an irregular method, but when electric
waves fall upon them they are " polarised," order is installed. Tliey
are marshalled in serried ranks, they are subject to pressure — in
fact, as Prof. Oliver Lodge expresses it, they " cohere " — electrical
contact ensues and a current passes. The resistance of such a space
falls from infinity to about five ohms. The electric resistance of
Marconi's relay — that is, the resistance of the thin disc of loose
powder — is practically infinite when it is in its normal or disordered
condition. It is, then, in fact, an insulator. This resistance drops
sometimes to five ohms, when the absorption of the electric waves by
it is intense. It therefore becomes a conductor. It may be, as sug-
gested by Prof. Lodge, that we have in the measurement of the variable
resistance of this instrument a means of determining the intensity of
the energy falling upon it. This variation is being investigated both
as regards the magnitude of the energy and the frequency of the
incident waves. Now such electrical effects are well known. In
1866 Mr. S. A. Varley introduced a lightning protector constructed
like the above tube, but made of boxwood and containing powdered
carbon. It was fixed as a shunt to the instrument to be protected.
It acted well, but it was subject to this coherence, which rendered

1897.

071 Signalling through Space without Win

473

the cure more troublesome tlian the disease, and its use had to be
abandoned. The same action is very common in granulated carbon
microphones like Huuning's, and shaking has to be resorted to to
decohere the carbon particles to their normal state. Mens. E. Branly
(1890) showed the effect with copper, aluminium and iron filings.
Jr'rof. Oliver Lodge, who has done more than anyone else in England
to illustrate and popularise the work of Hertz and his followers, has
given the name " coherer " to this form of apparatus. Marconi
" decoheres " by making the local current very rapidly vibrate a small
hammer head against the glass tube, which it does effectually, and in

6

^

STEEPHOLM

<» Marconi Experiments
•"— Eiectro-Magnetio Induction CxporlmontS

eREAN OOWMn^

Fig. 3. — Map of locality where the experiments were carried out.

doing so makes such a sound that reading Morse characters is easy.
The same current that decoheres can also record Morse signals on
paper by ink. The exhausted tube has two wings which, by their
size, tune the receiver to the transmitter by varying the capacity of
the apparatus.* Choking coils prevent the energy escaping. The
analogy to Prof. Silvanus Thompson's wave apparatus is evident.
Oscillations set up in the transmitter fall upon the receiver tuned in

• The period of vibration of a circuit is given by the equation T = 2 ir VK L,
80 that we have simply to vary either the capacity K or the so-called " self-
induction " L to tune the receiver to any frequency. It is simpler to vary K.

474

Mr, W. H. Preece

[June 4,

sympathy with it, coherence follows, currents are excited and signals
made.

In open clear spaces within sight of each other nothing more is
wanted, but when obstacles intervene and great distances are in
question height is needed — tall masts, kites and balloons have been
used. Excellent signals have been transmitted between Penarth and
Brean Down, near Weston-super-Mare, across the Bristol Clianijel, a
distance of nearly nine miles (Fig. 3). [The system was here shown
in operation]

Mirrors also assist and intensify the effects. They were used in
the earlier exj^eriments, but they have been laid aside for the present,
for they are not only expensive to make, but they occupy much time
in manufacture.

It is curious that hills and apparent obstructions fail to obstruct.
The reason is probably the fact that the lines of force escaj)e these
hills. When the ether is entangled in matter of different degrees of
inductivity the lines are curved as in fact they are in light. Fig. 4

Fig. 4. — Diagram illustrating the way in which liills are bridged by the
electric waves.

shows how a hill is virtually bridged over by these lines, and conse-
quently some electric waves fall on the relay. Weather seems to
have no influence : rain, fogs, snow and wind avail nothing.

The wings shown in Fig. 2 may be removed. One pole can be
connected with earth, and the other extended up to the top of the
mast, or fastened to a balloon by means of a wire. The wire and
balloon or kite covered with tin foil becomes the wing. In this case
one pole of the transmitter must also be connected with earth. This
is shown by Fig. 5.

There are some apparent anomalies that have developed them-
selves during the experiments. Mr. Marconi finds that his relay acts
even when it is placed in a perfectly closed metallic box. This is
the fact that has given rise to the rumour that he can blow up an
ironclad ship. This might be true if he could plant his properly
tuned receiver in the magazine of an enemy's ship. Many other
funny things could be done if this were possible. I remember in my
childhood that Capt. Warner blew up a ship at a great distance off

1897.]

on Signalling through Space ivithout Wires.

475

Brighton. How this was done was never known, for his secret died
shortly afterwards with him. It certainly was not by means of
Marconi's relay.

I he distance to which signals have been sent is remarkable. On
Salisbury Plain Mr. Marconi covered a distance of four miles. In
the Bristol Channel this has been extended to over eight miles, and
we have by no means reached the limit. It is interesting to read the
surmises of others. Half a mile was the wildest dream.*

It is easy to transmit many messages in any direction at the same
time. It is only necessary to tune the transmitters and receivers to
the same frequency or " note." I could show this here, but we are

Fig. 5. — Diagram of Marconi connections when using pole or kite.

bothered by reflection from the walls. This does not happen in open
space. Tuning is very easy. It is simply necessary to vary the
capacity of the receiver, and this is done by increasing the length of
the wings W in Fig. 2. The proper length is found experimentally
close to the transmitter. It is practically impossible to do so far away.

* "Unfortunately at present we cannot detect the electromagnetic waves
more than 100 feet from their source." — Trowbridge, 1897, ' What is Elec-
tricdry,' page 256.

"I mention 40 yards because that was one of the first out of door experi-
ments, but I should think that something more like half a mile was nearer the
limit of sensibility. However, this is a rash statement not at present verified." —
Oliver Lodge, 1894, ' The Work of Hertz,' page 18.

476 Mr. W. H. Preece on Signalling iciihout Wires. [June 4,

It has been said tLat Mr. Marconi has done nothing new. He has
not discovered any new rays ; his transmitter is comparatively old ; his
receiver is based on Branly's coherer. Columbus did not invent the
egg, but he showed how to make it stand on its end, and Marconi has
produced from known means a new electric eye more delicate than
any known electrical instrument, and a new system of telegraphy that
will reach places hitherto inaccessible. There are a great many
practical points connected with this system that require to be
threshed out in a practical manner before it can be placed on the
market, but enough has been done to prove its value, and to shovv
that for shipping and lighthouse purposes it will be a great and
valuable acquisition.

[W. H. P.]

1897.] Diamonds. 477

WEEKLY EVENING MEETING,
Friday, June 11, 1897.

Sir Frederick Abel, Bart. K.C.B. D.C.L. LL.D. F.E.S.
Vice-President, in the Chair.

William Crookes, Esq. F.K.S. M.B.L

Diamonds.

It seems but the other day I saw London in a blaze of illumination
to celebrate Her Majesty's happy accession to the throne. As in a
few days the whole Empire will be celebrating the Diamond Jubilee
of our Queen, who will then have reigned over her multitudinous
subjects for sixty years, what more suitable topic can I bring before
you than than that of Diamonds ! One often hears the question
asked, " Why Diamond Jubilee ? " I suppose it is a symbol intended
to give a faint notion of the pure brilliancy and durability of the
Queen's reign ; and in thus associating Her Majesty with the precious
Diamond, to convey an idea of those noble qualities public and private
which have earned for her the love, fealty and reverence of her sub-
jects.

From the earliest times the diamond has occupied men's minds.
It has been a perennial puzzle — one of the riddles of creation. The
philosopher Steffans is accredited with the dictum that, " Diamond is
quartz which has arrived at self-consciousness!" and an eminent
geologist has parodied this metaphysical definition, saying : " Quartz
is diamond which has become insane ! "

Professor Maskelyne, in a lecture " On Diamonds," thirty-seven
years ago,* in this very theatre, said, " The diamond is a substance
which transcends all others in certain properties to which it is
indebted for its usefulness in the arts and its beauty as an ornament.
Thus, on the one hand, it is the hardest substance found in nature or
fashioned by art. Its reflecting power and refractive energy, on the
other hand, exceed those of all other colourless bodies, while it yields
to none in the perfection of its pellucidity " — but he was constrained
to add " The formation of the diamond is an unsolved problem."

Recently the subject has attracted many men of science. The
development of electricity, with the introduction of the electric fur-
nace, has facilitated research, and I think I am justified in saying that
if the diamond problem is not actually solved, it is certainly no longer
insoluble.

* ' Chemical News,' vol. i. p. 208.

478 Mr. William Crookes [June 11,

In the early part of last year, accompanied by my wife, I visited
some of our Colonies in South Africa, and spent a considerable time
in the neighbourhood of the famous Diamond Mines of Kimberley,
where I had an exceptionally good opportunity of studying the pecu-
liar geological formation, and of noting interesting facts connected
with the occurrence of the precious stone which forms the subject of
this evening's lecture.

Although the experiments I wish to bring before you are chiefly
connected with the physical and chemical properties of diamonds, and
of the light that recent researches throws upon their probable forma-
tion, it will possibly act as a kind of compensation for the dryness of
some of the theoretical points if with the help of a few photof^raphs *
taken on the spot, I bring before your very eyes the general character
of the famous mines and their surroundings.

The most famous diamond mines are Kimberley, De Beers,
Dutoitspan, Bulfontein and Wesselton. They are situated in lati-
tude 28° 43' South, and longitude 24° 46' East. Kimberley town
is 4042 feet above sea-level. Other mines in the district, as yet
unimportant, are worked for diamonds. Kimberley is practically in
the centre of the present diamond-producing area. Besides these
mines, there are in the Orange Free State, about 60 miles from the
Kimberley diamond region, two others of some importance known as
Jagersfontein and Coffeefontein.

Before describing the present mode of diamond extraction followed
in the leading mines, I will commence with the so-called " Kiver
Washings," where, in their original simplicity, can be seen the
methods of work and the simple machinery long since discarded in
the large centres (Fig. 1). These drifts or "river-washings" present
an interesting phase of diamond industry. The work is carried out
in the crude fashion of early diamond discovery, every man working
on his own little claim, assisted by a few natives, and employing
primitive machinery. The chief centre of the river washings is at
Klipdam No. 2, about 30 miles to the north-west of Kimberley. The
road to Klipdam No. 2 involves a journey of about a dozen miles in
one of the old African coaches now becoming obsolete through the
spread of railways. Eoad there is none — only a track across the
veldt made by countless teams of oxen and mule«.

Diamonds from the "river washings " are of all kinds, as if every
mine in the neighbourhood contributed. The samples are much
rolled and etched, and contain a fair proportion of stones of very good
quality, as if only the better and larger stones had survived the ordeal
of knocking about.

Diamonds from the drift fetch about 40 per cent, more than those

* Of the photographs Illustrating this lecture, Nos. 4 and 7 are from plans
lent by Mr. Gardner Williams, and Nos. 3, 5, 6, 8, 9, 12, 13 and 18 are copies of
photographs purchased at Kimberley. The remaining twenty were photographed
by myself.

ll

-Aliu\ lal L)iann>nJ Washin.?-

2.— Market Squuiw. kiiiiberley

■Suburbs of Kimberlev,

■OOP 'J I T Z ' C T

^^^^.

ett"^

CONSOLIDATED

w'^rst,.

ALEX'^fJOe'^SrONTtl.'-- 3£ ^AU.yOnEiO^rotJ r E •

4. --Plan of the Diamond Mines.

1897.] on Diamonds. 479

from Kimberley : taking the yield of the Kimberley and De Beers
mines as worth, all round, large and small, 26s. &d. a carat, the drift
diamonds are worth 40s.

The town of Kimberley is a remarkable instance of rapid growth
(Fig. 2). It has an excellent clnb and one of the best public
libraries in South Africa. Parts of the town, affectionately called
" the camp " by the older inhabitants, are still in the galvanised iron
or " tin shanty " stage (Fig. 3), and the general appearance is unlovely
and depressing. Reunert reckons that over a million trees have been
felled to supply timber for the mines, and the whole country within
a radius of 100 miles has been denuded of wood, with most injurious
effects to the climate. The extreme dryness of the air, and the
absence of trees to break the force of the wind and temper the heat
of the sun, probably account for the dust storms so frequent in
summer. The temperature in the day frequently rises to 100° in the
shade, but in so dry a climate this is not unpleasant, and I felt less
oppressed than I did in London the previous September. Moreover,
in Kimberley, owing to the high altitude, the nights are always
cool.

The five noted diamond mines are all contained in a circle
3^ miles in diameter (Fig. 4). The mines are irregularly shaped
round or oval pipes, extending vertically downwards to an unknown
depth, retaining about the same diameter throughout. They are
said to be volcanic necks (Fig. 6), filled from below with a hetero-
geneous mixture of fragments of the surrounding rocks, and of
older rocks such as granite, mingled and cemented with a bluish
coloured hard clayey mass, in which famous blue the diamonds are
hidden.

The breccia filling the pipes, usually called " blue ground," is a
collection of fragments of shale, eruptive rocks, boulders, and crystals
of many kinds of minerals.

The Kimberley mine for the first 70 or 80 feet is filled with what
is called "yellow ground," and below that with "blue ground."
This superposed yellow on blue is common to all the mines. The
blue is the unaltered ground, and owes its colour chiefly to the
presence of lower oxides of iron. When atmospheric influences have
access to the iron it becomes peroxidised, and the ground assumes a
yellow colour. The thickness of yellow earth in the mines is there-
fore a measure of the depth of penetration of air and moisture. The
colour does not affect the yield of diamonds.

The diamantiferous clay or blue ground shows no signs of passing
through great heat, as the fragments in the breccia are not fused at
the edges. The eruptive force was probably steam or water-gas,
acting under great pressure but at no high temperature. According
to Mr. Dunn, in the Kimberley mine, at a depth of 120 feet, several
small fresh-water shells were discovered in what appeared to be
undisturbed material.

Let me cite a description of a visit to Kimberley in 1872, by

480 Mr. William Croohes [June 11,

Mr. PatersoD, taken from a paper read to the Geologists' Association,
which gives a graphic picture of the early days of the Kimberley
mine : —

" The New Rush diggings (as the Kimberley Mine was first
called) are all going forward in an oval space enclosed around by
the trap dyke, of which the larger diameter is about 1000 feet, while
the shorter is not more than 700 feet in length. Here all the claims
of 31 feet square each are marked out with roadways about 12 feet in
width, occurring every 60 feet. Upon these roadways, beside a short
pole fixed into the roadway, sits the owner of the claim with watchful
eye upon the KaflBr diggers below, who fill, and hoist by means of a
pulley fixed to the pole above, bucketful alter bucketful of the picked
marl stuff in which the diamonds occur."

Soon came the difftculty how to continue working the host of
separate claims without infringements. A system of rope haulage
was then adopted. This mode of haulage continued in vogue during
the whole of 1873, and if the appearance of the mine was less
picturesque than when roadways existed, it was, by moonlight
particularly, a weird and beautiful sight.

But the mine was now threatened in two other quarters. The
removal of the blue ground undermined the support from the walls
of the pipe, and frequent falls of reef occurred, not only burying
valuable claims but endangering the lives of workers below (Fig. 6).
Moreover, as the workings deepened, water made its appearance,
necessitating pumping.

It soon became evident that open workings were doomed, and by
degrees the present system of underground working was devised.

During this time of perplexity, individual miners who might have
managed one or two claims near the surface could not continue work
in the face of harassing difiiculties and heavy expenses. Thus the
claims gradually changed hands until the mine became the property
first of a comparatively small number of capitalists, then of a smaller
number of limited liability companies, until the whole of the mines
have practically become the property of the " De Beers Consolidated
Mines, Limited."

The areas of the mines are : —

Kimberley 33 acres.

De Beers 22 „

Dutoitspan . 45 „

Bulfontein 36 „

The contents of the several pipes are not absolutely identical.
The diamonds from each pipe differ in character, showing that the
upflow was not simultaneous from one large reservoir below but was
the result of several independent eruptions. Even in the same mine
there are visible traces of more than one eruption.

The blue ground varies in its yield of diamonds in different mines,

5.~Kimhtrle\- A\ine--VoIcanic Neck

6. — Kimberlev Mine in 1872.

SECTION OF KIMBERLEY MINE
LOOKING WEST

^^s:^JJ^:

7.— Section of Kimberlev Mine.

-De Beers Mine.— Underground Workings.

g. — De Beers Mine. ^Underground Workings.

lo.— The Depositing Floors.

1897.] on Diamonds. 481

but is pretty constant in the same mine. In 1890, the yield per load
of blue ground was —

. From the Kimberley mine from 1' 25 to 1*5 carat.
„ De Beers mine „ 1-20 ,,1-33 „

„ Dutoitspan mine „ 0-17 „ 0*5 „
„ Bulfonteiu mine „ 0*5 „ 0'33 „

In the face of constant developments I can only describe the
system in use at the time of my visit. Shafts are suuk in the solid
rock at a sufficient distance from the pipe to be safe against reef
movements in the open mine (Fig. 7). Tunnels are driven from this
shaft at different levels, about 120 feet aj)art, to cross the mine from
west to east. These tunnels are connected by two others running
north and south, one near the west side of the mine and one midway
between it and the east margin of the mine. From the east and west
tunnels offsets are driven to the surrounding rock. When near the
rock, the offsets widen into galleries, these in turn being stoped on
the sides until they meet, and upwards until they break through the
blue ground. The fallen reef with which the upper part of the mine
is filled sinks and partially fills the open space. The workmen then
stand on the fallen reef and drill the blue ground overhead, and as
the roof is blasted back the debris follows. When stoping between
two tunnels the blue is stoped up to the debris about midway between
the two tunnels. The upper levels are worked back in advance of
the lower levels, and tlie works assume the shape of irregular terraces.
The main levels are from 90 to 120 feet apart, with intermediate
levels every 30 feet. Hoisting is done from only one level at a time
through the same shaft. By this ingenious method of mining every
portion of blue ground is excavated and raised to the surface, the
rubbish on the top gradually sinking and taking its place.

The pcene below ground in the labyrinth of galleries is bewil-
dering in its complexity, and very unlike the popular notion of a
diamond mine (Figs. 8, 9). All below is dirt, mud, grime ; half naked
men, black as ebony, muscular as athletes, dripping with perspiration,
are seen in every direction, hammering, picking, shovelling, wheeling
the trucks to and fro, keeping up a weird chant which rises in force
and rhythm when a titanic task calls for excessive muscular strain.
The whole scene is more suggestive of a coal mine than a diamond
mine, and all this mighty organisation, this strenuous expenditure of
energy, this costly machinery, this ceaseless toil of skilled and black
labour, goes on day and night, just to win a few stones wherewith to
deck my lady's finger !

Owing to the refractory character of blue ground fresh from the
mines, it has to be exposed to atmospheric influences before it will
pulverise under the action of water and mechauical treatment. It is
brought to the surface and spread on the floors (Fig. 10). Soon the
heat of the sun and moisture produce a wonderful effect. Boulders,
hard as ordinary sandstone when fresh from the mine, commence to

482 Mr. William CrooJces [June 11,

crumble. At this stage the treatment of the diamonds assumes more
the nature of farming than mining. To assist pulverisation by ex-
posing the larger pieces to atmospheric influences, the ground is
frequently harrowed and occasionally watered. The length of time
necessary for crumbling the ground preparatory to washing, depends
on the season of the year and the amount of rain. The longer the
ground remains exposed the better it is for washing. When the
process is complete the softened friable blue clay is again loaded into
trucks and taken to the washing machinery, where it is agitated with
water and forced tlirough a series of revolving cylinders j^erforated
with holes about an inch in diameter ; incorrigible lumps that will
not pass the cylinders are again subjected either to the weathering
process or passed between crushing rollers.

The fine ground which has passed through the holes in the
cylinder, together with a plentiful current of water, flows into the
washing pans (Fig. 11). These pans are of iron, 14 feet in diameter,
furnished with ten arras each having six or seven teeth. The teeth
are set to form a spiral, so that when the arms revolve the teeth carry
the heavy deposit to the outer rim of the pan, while the lighter
material passes towards the centre and is carried from the pan by the
flow of water. The heavy deposit contains the diamonds. It remains
on the bottom of the pan and near its outer rim. This deposit is
drawn off every twelve hours by means of a broad slot in the bottom
of the pan. The average quantity of blue ground passed through each
pan is from 400 to 450 loads in ten hours. The deposit left in each
pan after putting through the above number of loads amounts to
three or four loads, which go to the pulsator for further concentra-
tion.

The pulsator (Fig. 12) is an ingeniously designed, somewhat com-
plicated machine for dealing with the diamantiferous gravel already
reduced one hundred times from the blue ground ; the pulsator still
further concentrating it till the stones can be picked out by hand.
The value of the diamonds in a load of original blue ground is about
30,s., the gravel sent to the pulsator from the pans, reduced a hundred-
fold, is worth 1601. a load.

The sorting room in the pulsator house is long, narrow and well
lighted. Here the rich gravel is brought in wet, a sieveful at a
time, and is dumped in a heap on tables covered with iron plates.
The tables at one end take the coarsest lumps, next comes the gravel
which passed the |-inch holes, then the next in order, and so on.
The first sorting, where the danger of robbery is greatest, is done
by thoroughly trustworthy white men. Sweeping the heap of gravel
to the right, the sorter scrapes a little of it to the centre of the table
by means of a flat piece of sheet zinc (Fig. 13). With this tool he
rapidly surveys the grains, seizes the diamonds, and puts them into
a little tin box in front of him. The stuff is then swept off to the left,
and another lot taken, and so on, till the sieveful of gravel is ex-
hausted and another brought in.

II. — De Beers Washing- and Concentratino; Machinery.

12. — The Pulsator.

3-— Sorting- Gravel for Diamonds.

I.. — De Beers Diamond Office. — Valuators' Table.

1897.]

on Diamonds,

483

The diamond has a peculiar lustre, impossible to mistake. On
the sorting table the stones look like clear pieces of gum arabic,
but with an intrinsic lustre which makes a conspicuous shine among
the other stones.

Watching the white men in the sorting room is an experience but
tame compared to the excitement of taking a sorter's place at the big
diamond table and disinterring from the gravel diamonds usually
described as the iinest and biggest found for many a day. The
interest, however, abates when the amateur sorter is told that the
jewels may not be carried away as mementos !

Sometimes as many as 8000 carats of diamonds are separated in
one day, representing about 10,000Z. in value.

Diamonds occur in all shades, from deep yellow to pure white
and jet black, from deep brown to light cinnamon ; they are also
green, blue, pink, yellow, orange and opaque.

From the pulsator sorting room the stones are taken to the
Diamond Office to be cleaned in acids and sorted into classes by the
valuators, according to colour and purity. It is a sight for Aladdin
to see the valuators at work in the strong-room of the De Beers
Company at Kimberley (Fig. 14). The tables are literally heaped
with stones won from the rough blue ground — stones of all sizes,
purified, flashing and of inestimable price ; stones that will be
coveted by men and women all the world over ; and last, but not least,
stones that are probably destined to largely influence the development
and history of a whole huge continent.

When the diamantiferous gravel has been washed down to a point
at which the stones can be picked out by hand, a good plan for
separating them is by their specific gravities. The following table
^ives the specific gravities of the minerals found on the sorting tables.
I have also included the specifi.c gravities of two useful liquids.

This table shows that if I throw the whole mixture of minerals
into methylene iodide, the hornblende and all above that mineral will
rise to the surface ; while the diamond and all minerals below will
sink to the bottom. If I take these heavy minerals, and throw them
into thallium lead acetate, tliey will all sink except the diamond, which
floats and can be skimmed ofi".

Hard graphite
Quartzite and granite

Beryl

Mica

Hornblende
Methylene iodide ..

Specific
Gravity.
, 2-5
, 2-6
2-7
, 2-8
, 3-0
, 3-3

Diamond 3' 5

Specific
Gravity.

Thallium lead acetate .. 3*6

Garnet 3-7

Corundum 3" 9

Zircon 4*4

Barytes 4*5

Chrome and titanic iron ore 4 • 7

Magnetite S'O

In illustration, I have arranged an experiment. In front of the
lantern is a cell containing a dense liquid ; when I throw into it
several minerals of different specific gravities, some sink whilst

484 Mr. William Crookes [June 11,

others swim, aud these swimmers can easily be skimmed from the
surface.

With gems like diamonds, where infinite riches are concentrated
in so small a bulk, it is not surprising that safeguards against rob-
bery are elaborate. The Illicit Diamond Buying (I.D.B.) laws are
stringent, and the searching, rendered easy by the " compounding " of
the natives, is of a drastic character. In fact, it is very difficult for a
native employe to steal diamonds ; even were he to succeed, it would
be almost impossible to dispose of them, as a potential buyer would
prefer to secure the safe reward for detecting a theft rather than run
the serious risk of doing convict work on the Cape Town Breakwater
for a couple of years. Before the passing of the " Diamond Trade
Act " the value of stolen diamonds reached nearly one million sterling
per annum.

One great safeguard against robbery is the " compound " system
of looking after the natives (Fig. 15). A " compound " is a large
square, about 20 acres in extent, surrounded by rows of one-story
buildings of corrugated iron. These are divided into rooms each
holding about twenty natives. A high iron fence is erected around
the compound, 10 feet from the buildings. W ithin the enclosure is a
store where the necessaries of life are supplied to the natives at a
reduced price, and wood and water free of charge. In the middle is
a large swimming-bath with fresh water running through it. The
rest of the space is devoted to games, dances, concerts, and any other
amusement the native mind can desire. In case of acci^lent or illness
there is a well-appointed hospital where the sick are tended. Medical
supervision, nurses and food are supplied free by the Company.

As a rule the better class of natives — the Zulus, Matabeles,
Basutos, Bechuanas — when well treated, are honest and loyal.

In the compound are to be seen representatives of nearly all the
picked types of African tribes (Fig. 16). Each tribe keeps to itself,
and to go round the buildings skirting the compound is an admirable
object lesson in ethnology. At one point is a group of Zulus;
next we come to Fingoes ; then Basutos ; beyond come Matabele
(Fig. 17), Bechuanas, Pondos, Swazis, and other less-known tribes,
each forming a distinct group, or wandering around making friendly
calls. We went one afternoon to the l)e Beers compound when most
of the natives were assembled, and having a camera with me I was
naturally glad to get as many photographs as I could. I have to
thank Captain Dallas, Mr. Moses, and Mr. Mandy, the Superintend-
ents of the respective compounds, who speak all the dialects fluently,
for their kindness in showing us round aud improvising dances and
concerts (Fig. 18), for the benefit of my camera.

The clothing in the compound is diverse and original (Fig. 19).
Some of the men are great dandies, whilst others think that in so hot
a climate a bright coloured pocket-handkerchief or " a pair of spec-
tacles and a smile " is as great a compliance with the requirements of
civilisation as can be expected.

5---De Beers Compound.

[6.— De Beers Compound.

[?.— De Beers Compound.— Matabele War Dance.

[8 — De Beers Compound.— Amateur Orchestra.

ig. — De Beers Compound.

20— Groups of Diamond Crystals.

1897.] on Diamonds. 485

So distinctive are the characters in diamonds from each mine that
an experienced buyer at once tells the locality of any particular
parcel of stones. De Beers and Kimberley mines are distinguished
by large yellowish crystals. Dutoitspan yields many coloured stones,
while Bulfontein — half a mile off — produces small white stones,
occasionally speckled and flawed, but rarely coloured. Diamonds
Irom the Wesselton mine are nearly all irregular in shape ; a perfect
crystal is rare, and most of the stones are white, few yellow.
Diamonds from the Leicester mine have a frosted, etched appearance ;
they are white, the crystallisation irregular (" cross-grained "), and
they are very hard. The newly discovered "■ Newlands " mines in
Griqualand West are remarkable for the whiteness of their diamonds
and for their many perfect octahedral crystals. Jagersfoutein stones
in the Orange Free State, take the prize for purity of colour and
brilliancy, and they show that so-called " steely " lustre characteristic
of old Indian gems. Stones from Jagerslontein are worth nearly
double those from Kimberley and De Beers.

Monster diamonds are not so uncommon as is generally supposed.
DianKmds weighing over an ounce (151-5 carats) are not infrequent
at Kimberley, and there would be no difficulty in getting together a
hundred of them. Not long ago, in one parcel of stones at the office
of Wernher, Beit and Co., I saw eight perfect crystals, each over an
ounce, and one that weighed two ounces (Fig. 20). The largest
known diamond — a true mountain of light — weighs 970 carats, over
half a pound. It was found four years ago at Jagersfoutein. It is
perfection in colour, but has a small black spot in the centre.
Diamonds smaller than a small fraction of a grain elude the sorters
and are lost. A microscopic examination of blue ground from Kim-
berley, after treatment with appropriate solvents, shows the presence
of microscopic diamonds, white, coloured and black, also of boart
and carbonado.

From two to three million carats of diamonds are turned out of
the Kimberley mines in a year, and as five million carats go to the
ton, this represents half a ton of diamonds. To the end of 1892, ten
tons of diamonds had come from these mines, valued at 60,000,000/.
sterling. This mass of blazing diamonds could be accommodated in
a box five feet square and six feet high.

The diamond is a luxury for which there is only a limited demand.
From 4 to 4^ millions sterling is as much as is spent annually in
diamonds ; if production is not regulated by demand, there will be
over-production, and the trade will sutfer. By regulating the out-
put, since the consolidation in 1888 the directors have succeeded in
maintaining prices.

Outside companies and individuals collect diamonds to the value
of about a million annually.

Intermediate between soft carbon and diamond come the graphites.
The name graphite is given to a variety of carbon, generally crystal-
line, which in an oxidising mixture of chlorate of potassium and

Vol. XY. (No. 91.) 2 k

486 Mr. William CrooJces [June 11,

nitric acid forms graphitic acid easy to recognise. Graphites are
of varying densities, from 2*0 to 3*0, and generally of crystalline
aspect. Graphite and diamond pass insensibly into one another.
Hard graphite and soft diamond are near the same specific gravity.
Tiie difference appears to be one of pressure at the time of formation.
Some forms of graphite exhibit a remarkable property, by which
it is possible to ascertain approximately the temperature at which
they were formed, or to which they have subsequently been exposed.
Graphites are divided into "sprouting" and "non-sprouting."
When obtained by simple elevation of temperature in the arc or the
electric furnace they do not sprout; but when they are formed by
dissolving carbon in a metal at a high temperature and then allowing
the graphite to separate out on cooling, the sprouting variety is
formed. One of the best varieties is that which can be separated
from platinum in ebullition in a carbon crucible. The phenomenon
of sprouting is easily shown. I place a few grains in a test-tube and
heat it to about 170° C, when, as you see, it increases enormously in
bulk and fills the tube with a light form of amorphous carbon.

The resistance of a graphite to oxidising agents is greater the
higher the temperature to which it has previously been exposed.
Graphites which are easily attacked by a mixture of fuming nitric
acid and potassium chlorate are rendered more resistant by strong
heat in the electric furnace.

I will now briefly survey the chief chemical and physical
characteristics of the diamond, showing you by the way a few
experiments that bear upon the subject.

When heated in air or oxygen to a temperature varying from
760° to 875° C. according to its hardness, the diamond burns with
production of carbonic acid. It leaves an extremely light ash, some-
times retaining the shape of the crystal, consisting of iron, lime,
magnesia, silica, and titanium. In boart and carbonado the amount
of ash sometimes rises to 4 per cent., but in clear crystallised diamonds
it is seldom higher than 0*05 per cent. By far the largest constituent
of the ash is iron.

The following table shows the temperatures of combustion in
oxygen of different kinds of carbon : —

°C.

Conclensed vapour of carbon 650

Carbon from sugar, heated in an electrical furnace.. .. 660

Artificial graphites, generally 660

Graphite from ordinary cast iron 670

Carbon from hlue ground, of an ochrey colour 6 0

„ „ very hard and black .. .. 710

Diamond, soft Brazilian 760

„ hard Kimberley 780

Boart from Brazil 790

„ from Kimberley 790

., very hard, impossible to cut . c . . 900

At the risk of repeating an experiment shown so well at this

2i.-Crystal of Diamond, showing Triangular Mark!

22.— Triangular Markings on a Crystal of Diamond (x ic

2}.— Marking:s developed on smooth surface of Diamond
bv combustion.

24. — Crystal of Diamond showing: curved edg:es.

1897.] on Diamonds. 487

table by Professor Dewar, I will beat a diamond to a bigh tempera-
ture in tbe oxyhydrogen blowpipe and tben suddenly throw it in
a vessel of liquid oxygen. Notice tbe brilliant light of its combus-
tion. I want you more especially to observe the wbite opaque
deposit forming in the liquid oxygen. This deposit is solid carbonic
acid produced by the combustion of the carbon. I will lead it
through baryta water, and you will see a white precipitate of barium
carbonate. With a little more care than is possible in a lecture I
could perform this experiment quantitatively, leading the carbonic
acid and oxygen, as tliey assume the gaseous state, through baryta
water, weighing the carbonate so formed, and showing that one
gramme of diamond would yield 3*666 grammes of carbonic acid —
the theoretical proportion for pure carbon.

Some crystals of diamonds have their surfaces beautifully marked
with equilateral triangles, interlaced and of varying sizes (Fig. 21).
Under the microscope these markings appear as shallow depressions
sharply cut out of the surrounding surface (Fig. 22), and these
depressions were suppcsed by Gustav Kose to indicate the probability
that the diamonds at some previous time had been exposed to
incipient combustion. Rose also noted that striations appeared on
the surfaces of diamonds burnt before the blowpipe. This experi-
ment I have repeated on a clear smooth diamond, and have satisfied
myself that during combustion in the field of a microscope, before
the blowpipe, the surface becomes etched with markings very
ditferent in character from those naturally inscribed on crystals.
O'he artificial striae are cubical and closer massed, looking as if
the diamond d^uring combustion had been dissected into rectangular
flakes (Fig. 23), while the markings natural to crystals appear as if
produced by the crystallising force as they were being built up.

I exhibit on a diagram a form of graphite from the Kimberley
blue ground (reproduced from M. Moissan's work) which in its
crystalline appearance strangely resembles the surface of a diamond
whose internal structure has been partially dissected and barred by
combustion. It looks as if this piece of graphite was ready to
separate out of its solvent as diamond, but owing to some insufiicient
factor it retained its graphitic form.

The specific gravity of the diamond is from 3 '514 to 3*518.
For comparison, I give in tabular form the specific gravities of the
different varieties of carbon : —

Amorphous carbon 1*45 to !• 70

Graphite 2-11 „ 3-0

Hard gas coke 2-356

Boart 3-47 . 3-49

Carlonado 3- 50

Diamond 3 '514 „ 3*518

The diamond belongs to the isometric system of crystallography.
It frequently occurs with curved faces and edges (Fig. 24). Twin

2 K 2

488 Mr. William Croohes [June 11,

crystals (macles) are not uncommon. Having no double refraction
it should not act on polarised light. But, as is well known, if a
transparent body which does not so act is submitted to strain of an
irregular character it becomes doubly refracting, and in the polari-
scope reveals the existence of the strain by brilliant colours arranged
in a more or less defined pattern according to the state of tension
in which the crystal exists. Under polarised light I have examined
many hundred diamond crystals, and with few exceptions all show
the presence of internal tension. On rotating the polariser, the
black cross, which is most frequently seen, revolves round a par-
ticular point in the inside of the crystal, and on examining this
point with a high power, we see sometimes a slight flaw, more rarely
a minute cavity. The cavity is filled with gas at an enormous
pressure, and the strain is set up in the stone by the effort of the gas
to escape.

It is not uncommon for a diamond to explode soon after it
reaches the surface, and some have been known to burst in the
pockets of the miners or when held in the w^arm hand. Large
crystals are more liable to burst than smaller pieces. Valuable
stones have been destroyed in this way, and it is whispered that
cunning dealers are not averse to allowing responsible clients to
handle or carry in their warm pockets large crystals fresh from
the mine. By way of safeguard against explosion, some dealers
imbed large diamonds in raw potato to insure safe transit to
England.

I will project some diamonds on the screen by means of the
polarising microscope, and you will see by the colours how great
is the strain to which some of them are exposed.

In the substance of many diamonds we fiind enclosed black
uncrystallised particles of graphite. There also occur what may
be considered intermediate forms between the well-crystallised
diamond and graphite. These are "boart" and "carbonado."
Boart is an imperfectly crystallised diamond, having no clear por-
tions, and therefore useless for gems. Boart is frequently found
in spherical globules, and may be of all colours. It is so hard that
it is used in rock-drilling, and when crushed it is employed for
cutting and polishing other stones. Carbonado is the Brazilian
term for a still less perfectly crystallised form of carbon. It is
equally hard, and occurs in porous masses, and in massive black
pebbles, sometimes weighing a couple or more ounces.

Diamonds vary considerably in hardness, and even different parts
of the same crystal are decidedly different in their resistance to
cutting and grinding. The famous Koh-i-noor, when cut into its
present form, showed a notable variation in hardness. In cutting
one of the facets near a yellow flaw, the crystal became harder and
harder the further it was cut into, until, after working the mill for
six hours at the usual speed of 2400 revolutions a minute, little
impression was made. The speed was accordingly increased to more

1897.] on Diamonds. 489

than 3000, wten the work slowly proceeded. Other portions of
the stone were found to be comparatively soft, and became harder as
the outside was cut away.

Beautifully white diamonds have been found at Inverel, New
South Wales, and from the rich yield of the mine and the white
colour of the stones, great things were expected. A parcel of
many hundred carats came to England, when it was found they
were so hard as to be practically unworkable as gems, and I
believe they were ultimately sold for rock-boring purposes.

I will illustrate the intense hardness of the diamond by an
experiment. I place a diamond on the flattened apex of a conical
block of steel, and on the diamond I bring down a second cone of
steel. With the electric lantern I will project an image of the
diamond and steel faces on the screen, and force them together by
hydraulic power. You see I can squeeze the stone right into the
steel blocks without injuring it in the slightest degree.

But it is not the hardness of the diamond so much as its optical
qualities that make it so highly prized. It is one of the most
refracting substances in nature, and it also has the highest reflecting
properties. In the cutting of diamonds advantage is taken of these
qualities. When cut as a brilliant the facets on the lower side are
inclined so that light falls on them at an angle of 24° 13', at which
angle all the incident light is totally reflected. A well cut diamond
should appear opaque by transmitted light except at a small spot
in the middle where the table and culet are opposite. All the light
falling on the front of the stone is reflected from the facets, and
the light passing into the diamond is reflected from the interior
surfaces and refracted into colours when it passes out into the air,
giving rise to the lightnings and coruscations for which the diamond
is supreme above all other gems.

1 hold some of Mr. Streeter's magnificent diamonds in the elec-
tric light, and by transmitted light you will see they are black, while
by reflected light they fill the room with radiance and colour.

The following table gives the refractive indices of diamonds and
other bodies : —

Refeactive Indices for the D Line.

Chromate oflead .. 2 -50-2 -97

Diamond 2-47-2-75

Phosphorus .. .. 2-22

Sulphur 2*12

Ruby 1-78

Thallium glass . . 1 ' 75

Iceland spar .. .. I'Go

Topaz 1-61

Beryl 1-60

Emerald 1-59

Flint glass 1-58

Quartz 1-55

Canada balsam .. .. 1*53

Crown glass 1 • 53

Fluor-spar 1*44

Ice 1-31

According to Dr. Gladstone, the specific refractive energy —

490 Mr. William Crookes [June 11,

will be for the D line 0 • 404, and the refraction equivalent, —

^ d '

will be 4-82.

After exposure for some time to the sun many diamonds glow
in a dark room. Some diamonds are fluorescent, aj^pearing milky
in sunlight. In a vacuum, exposed to a high-tension current of
electricity, diamonds phosphoresce of different colours, most South
African diamonds shining with a bluish light. Diamonds from other
localities emit bright blue, apricot, pale blue, red, yellowish-green,
orange, and pale green light. The most phosphorescent diamonds
are those which are fluorescent in the sun. One beautiful green
diamond in my collection, when phosphorescing in a good vacuum,
gives almost as much light as a candle, and you can easily read by its
rays. The light is pale green, tending to white.

I will now draw your attention to a strange property of the
diamond, which at first sight might seem to argue against the great
permanence and unalterability of this stone. It has been ascertained
that the cause of phosphorescence is in some way connected with the
hammering of the gaseous molecules, violently driven from the
negative pole, on to the surface of the body under examination, and so
great is the energy of the bombardment, that impinging on a piece of
platinum or even iridium, the metal will actually melt. When the
diamond is thus bombarded in a radiant matter tube the result is
startling. It not only phosphoresces but assumes a brown colour,
and when the action is long continued becomes almost black.

I will project a diamond on the screen and bombard it with
radiant matter before your eyes. I do not like to anticipate a
failure, but here I am entirely at the mercy of my diamond. I
cannot rehearse this experiment beforehand, and it may happen that
the diamond I have selected will not blacken in reasonable time.
Some visibly darken in a few minutes, while others, more leisurely in
their ways, require an hour.

This blackening is only superficial, but no ordinary means of
cleaning will remove the discoloration. Ordinary oxidising re-
agents have little or no effect in restoring the colour. The black
stain on the diamond is due to a form of graphite which is very
resistant to oxidation. It is not necessary to expose the diamond in
a vacuum to electrical excitement in order to produce this change.

I have already signified that there are various degrees of refrac-
toriness to chemical reagents among the difi'erent forms of graphite.
Some dissolve in strong nitric acid ; other forms of graphite re-
quire a mixture of highly concentrated nitric acid and potassium
chlorate to attack them, and even with this intensely powerful
agent some graphites resist longer than others. M. Moissan has
shown that the power of resistance to nitric acid and potassium
chlorate is in proportion to the temperature at which the graphite

1897.] on Diamonds. 491

was formed, and with tolerable certainty we can estimate this
temperature hy the resistance of the specimen of graphite to this
reagent.

The superficial dark coating on a diamond after exposure to mole-
cular bombardment I have proved to be graphite,* and M. Moissan f
has shown that this graphite, on account of its great resistance to
oxidising reagents, cannot have been formed at a lower temperature
than 3600° C.

It is therefore manifest that the bombarding molecules, carrying
with them an electric charge, and striking the diamond with enormous
velocity, raise the superficial layer to the temperature of the electric
arc, and turn it into graj)hite, whilst the mass of diamond and its
conductivity to heat are sufficient to keep down the general tempera-
ture to such a point that the tube appears scarcely more than warm
to the touch.

A similar action occurs with silver, the superficial layers of
which can be raised to a red heat without the whole mass becoming
more than warm. J

This conversion of diamond into graphite is, I believe, a pure
effect of heat. In 1880 § Professor Dewar in this theatre placed a
cry.^tal of diamond in a carbon tube through which a current of
hydrogen was maintained. The tube was heated from the outside by
an electric arc, and in a few minutes the diamond was converted into
graphite. I will now show you that a clear crystal of diamond, heated
in the electric arc (temjjerature 3600° C), is converted into graphite,
and this graphite is most refractory.

The diamond is remarkable in another respect. It is extremely
transparent to the Eontgen rays, whereas highly refracting glass,
used in imitation diamonds, is almost perfectly opaque to the rays
(Fig. 25). I exposed over a photographic plate to the X rays for a
few seconds the large Delhi diamond, of a fine pink colour, weighing
31J carats, a black diamond weighing 23 carats, together with an
imitation in glass of the pink diamond lent me by Mr. Streeter ; also
a flat triangular crystal of diamond of pure water, and a piece of glass
of the same shape and size. On development, the impression where
the diamond obscured the rays was found to be strong, showing that
most rays passed through, while the glass was practically opaque.
By this means imitation diamonds and some other false gems can
readily be detected and distinguished from the true gems. It would
take a good observer to distinguish my pure triangular diamond from
the adjacent glass imitation.

Speculations as to the probable origin of the diamond have been
greatly forwarded by patient research, and particularly by improved

* ' Chemical News,' vol. Ixxiv. p. 39, July 1896.

t ' Comptes Eendus,' cxxiv. p. 653.

% Proc. Roy. Soc. vol. 1. p. 99, June 1891.

§ ' Proceedings of the Royal Institution,' Jan. 16, 1880.

492 Mr. William Crockes [June 11,

means of obtaining high temperatures. Thanks to the success of
Professor Moissan, whose name will always be associated with the
artificial production of diamonds, we are able to-day to manufacture
diamonds in our laboratories — minutely microscopic, it is true — all
the same veritable fliamonds, with crystalline form and appearance,
colour, hardness, and action on light the same as the natural gem.

Until recent years carbon was considered absolutely non-volatile
and infusible ; but the enormous temperatures at the disposal of ex-
perimentalists— by the introduction of electricity — show that, instead
of breaking rules, carbon obeys the same laws that govern other bodies.
It volatilises at the ordinary pressure at a temperature of about 3600°O.,
and passes from the solid to the gaseous state without liquefying.
It has been found that other bodies which volatilise without liquefying
at the ordinary pressure will easily liquefy if pressure is added to
temperature. Thus, arsenic liquefies under the action of heat if the
pressure is increased ; it naturally follows that if | along with the
requisite temperature sufficient pressure is applied, liquefaction of
carbon will be likely to take place, when on cooling it will crystallise.
Put carbon at high temperatures is a most energetic chemical agent,
and if it can get hold of oxygen from the atmosphere or any compound
containing it, it will oxidise and fly off in the form of carbonic acid.
Heat and pressure therefore are of no avail unless the carbon can be
kept inert.

It has long been known that iron when melted dissolves carbon,
and on cooling liberates it in the form of graphite. Moissan dis-
covered that several other metals have similar properties, especially
silver; but iron is the best solvent for carbon. The quantity of
carbon entering into solution increases with the temperature, and on
cooling in ordinary circumstances it is largely deposited as crystalline
graphite.

Professor Dewar has made a calculation as to the Critical Pressure
of carbon — that is, the lowest pressure at which carbon can be got to
assume the liquid state at its critical tcmjierature, that is the highest
temperature at which liquefaction is possible. He starts from the
vaporising or boiling point of carbon, which, from the experiments of
Yiolle and others on tlie electric arc, is about 3600° C, or 3874°
Absolute. The critical point of a substance on the average is 1 * 5
times its absolute boiling point. Therefore the critical point of
carbon is 5811° Ab., or, say, 5800° Ab. But the absolute critical
temperature divided by the critical pressure is for elements never
less than 2 • 5. Then —

6800° A. ^ . -p^ 5800° A. ^qoh . i.
— =r— — = 2 • 5, or PCr = — -^ — , or 2d20 atmospheres.
PCr 2 • 5

The result is that the critical pressure of carbon is about 2300
atmospheres, or say 15 tons on the square inch. The highest critical
pressure recorded is that of water, amounting to 195 atmospheres,

1897.] on Diamonds. 493

and the lowest that of hydrogen, about 20 atmospheres. In other
words, the critical pressure of water is ten times that of hydrogen,
and the critical pressure of carbon is ten times that of water.

Now 15 tons on the square inch is not a difficult pressure to
obtain in a closed vessel. In their researches on the gases from
fired gunpowder and cordite, Sir Frederick Abel and Sir Andrew
Noble obtained in closed steel cylinders pressures as great as 95 tons
to the square inch, and temperatures as high as 4000° C. Here, then,
if the observations are correct, we have sufficient temperature and
enough pressure to liquefy carbon; and if the temperature could only
be allowed to act for a sufficient time on the carbon there is little
doubt that the artificial formation of diamonds would soon pass from
the microscopic stage to a scale more likely to satisfy the require-
ments of science, industry and personal decoration.

I now proceed to manufacture a diamond before your eyes — don't
think I yet have a talisman that will make me rich beyond the
dreams of avarice ! Hitherto the results have been very microscopic
and are chiefly of scientific interest in showing us Nature's workshop,
and how we may ultimately hope to vie with her in the manufacture
of diamonds. Unfortunately the operations of separating the diamond
from the iron and other bodies with which it is associated are some-
what proloniicd — nearly a fortnight being required to detach it from
the iron, graphite and other matters in which it is embedded. I can,
however, show the dilferent stages of the operations, and project on
the screen diamonds made in this manner.

In Paris recently I saw the operation carried out by M. Moissan,
the discoverer of this method of making carbon separate out in the
transparent crystalline form, and I can show you the operations
straight as it were from the inventor's laboratory. I am also
indebted to the Directors of the Notting Hill Electric Lighting
Co., and to the general manager, Mr. Schultz, for enabling me to
perform several operations at their central station, where currents of
500 amperes and 100 volts were placed at my disposal.

The lirst necessity is to select pure iron — free from sulphur,
silicon, phosphorus, &c. — and to pack it in a carbon crucible with
pure charcoal from sugar. Half a pound of this iron is then put
into the body of the electric furnace and a powerful arc formed close
above it between carbon poles, utilising a current of 700 amperes
at 40 volts pressure. The iron rapidly melts and saturates itself
with carbon. After a few minutes' heating to a temperature above
4000° C. — a temperature at which the lime of the furnace melts like
wax and volatilises in clouds — the current is stopped, and the
dazzling fiery crucible is plunged beneath the surface of cold water,
where it is held till it sinks below a red heat. As is well known,
iron increases in volume at the moment of passing from the liquid
to the solid state. The sudden cooling solidifies the outer layer of
iron and holds the inner molten mass in a tight grip. The expansion
of the inner liquid on solidifying produces an enormous pressure,

494 Mr. William Croohes [June 11,

and under the stress of this pressure the dissolved carbon separates
out in a transparent, dense, crystalline form — in fact, as diamond.

Now commences the tedious part of the process. The metallic
inf^ot is attacked with hot nitro-hjdrochloric acid until no more iron
is dissolved. The bulky residue consists chiefly of graj^hite, together
with translucent flakes of a chestnut-coloured carbon, black opaque
carbon of a density of from 3 * 0 to 3*5, and hard as diamonds — black
diamonds or carbonado, in fact — and a small portion of transparent
colourless diamonds showing crystalline structure. Besides these,
there may be carbide of silicon and corundum, arising from impurities
in the materials employed.

The residue is first heated for some hours with strong sulphuric
acid at the boiling point, with the cautious addition of powdered nitre.
It is then well washed and allowed for two days to soak in strong
hydrofluoric acid in the cold, then in boiling acid. After this treat-
ment the soft graphite will disappear, and most, if not all, of the
silicon compounds will be destroyed. Hot sulphuric acid is again
applied to destroy the fluorides, and the residue, well washed, is
repeatedly attacked with a mixture of the strongest nitric acid and
powdered potassium chlorate, kept warm, but to avoid explosions not
above 60° C. This ceremony must be repeated six or eight times,
when all the hard graphite will gradually be dissolved, and little
else left but graphitic oxide, diamond and the harder carbonado and
boart. The residue is fused for an hour in fluorhydrate of fluoride
of potassium, then boiled out in water, and again heated in sulphuric
acid. The well-washed grains which resist this energetic treatment
are dried, carefully deposited on a slide, and examined under the
microscope. Along with numerous pieces of black diamond are seen
transparent colourless pieces, some amorphous, others with a crystal-
line appearance, as I have attempted to reproduce in drawings.
Although many fragments of crystals occur, it is remarkable that I
have never seen a complete crystal. All appear broken up, as if on
being liberated from the intense pressure under which they were
formed they burst asunder. I have direct evidence of this phe-
nomenon. A very fine piece of artificial diamond, carefully mounted
by me on a microscopic slide, exploded during the night and covered
my slide with fragments. This bursting paroxysm is not unknown
at the Kimberley mines.

On the screen I will project fragments of artificial diamond
(Figs. 26, 27), some lent me by Professor Roberts- Austen, others
of my own make ; while on the wall you will see drawings of dia-
monds copied from M. Moissan's book on the Electric Furnace. Un-
fortunately these specimens are all microscopic. The largest arti-
ficial diamond, so far, is less than one millimetre across.

Laboratory diamonds burn in the air before the blowpipe to
carbonic acid ; and in lustre, crystalline form, optical properties,
density and hardness they are identical with the natural stone.

Many circumstances point to the conclusion that the diamond

1897.] on Diamonds. 495

of the chemist and the diamond of the mine are strangely akin as
to origin. It is conclusively proved that the diamond has not been
formed in situ in the blue ground. The diamond genesis must have
taken place at great depths under enormous pressure. The explosion
of large diamonds on coming to the surface shows extreme tension.
More diamonds are found in fragments and splinters than in perfect
crystals ; and it is noteworthy that although many of these splinters
and fragments are derived from the breaking up of a large crystal,
yet in no instance have pieces been found which could be fitted
together. Does not this fact point to the conclusion that the blue
ground is not their true matrix ? Nature does not make fragments
of crystals. As the edges of the crystals are still sharp and
unabraded, the locus of formation cannot have been very distant
from the present sites. There were probably many sites of crystal-
lisation differing in place and time, or we should not see such
distinctive characters in the gems from different mines, nor indeed
in the diamonds from different parts of the same mine.

How the great diamond pipes originally came into existence is
not difficult to understand, in the light of the foregoing facts. They
certainly were not burst through in the ordinary manner of volcanic
eruption ; the surrounding and enclosing walls show no signs of
igneous action, and are not shattered nor broken even when
touching the " blue ground." These pipes after they were pierced
were filled from below, and the diamonds formed at some previous
epoch too remote to imagine were erupted with a mud volcano,
together with all kinds of debris eroded from the adjacent rocks.
The direction of flow is seen in the upturned edges of some of the
strata of shale in the walls, although I was unable at great depths
to see any upturning in most parts of the walls of the De Beers
mine.

Let me again refer you to the picture of the section through the
Kimberley mine. There are many such pipes in the immediate
neighbourhood. It may be that each volcanic pipe is the vent for
its own special laboratory — a laboratory buried at vastly greater
depths than we have reached or are likely to reach — where the
temperature is comparable with that of the electric furnace, where
the pressure is fiercer than in our puny laboratories and the melting-
point higher, where no oxygen is present, and where masses of
carbon-saturated iron have taken centuries, perhaps thousands of
years, to cool to the solidifying point. Such being the conditions
the wonder is, not that diamonds are found as big as one's fist, but
that they are not found as big as one's head. The chemist arduously
manufactures infinitesimal diamonds, valueless as ornamental gems ;
but Nature, with unlimited temperature, inconceivable pressure and
gigantic material, to say nothing of measureless time, produces
without stint the dazzling, radiant, beautiful crystals I am enabled
to show you to-night.

The ferric origin of the diamond is corroborated in many ways.

496 Mr. William CrooJces [June 11,

The country round Kimberley is remarkable for its ferruginous
character, and iron-saturated soil is popularly regarded as one of
the indications of the near presence of diamonds. Certain artificial
diamonds present the appearance of an elongated drop. From
Kimberley I have with me diamonds which have exactly the appear-
ance of drops of liquid separated in a pasty condition and crystallised
on cooling (Fig. 28). At Kimberley and in other parts of the
world, diamonds have been found with little appearance of crystal,
lisation, but with rounded forms similar to those which a liquid
might assume if kept in the midst of another liquid with which it
would not mix. Other drops of liquid carbon retained above their
melting-point for sufficient time would coalesce with adjacent drops,
and on slow cooling would separate in the form of large perfect
crystals. Two drops, joining after incipient crystallisation, would
assume the not uncommon form of interpenetrating twin crystals.
Illustrations of these forms from Kimberley are here to-night.
Other modified circumstances would produce diamonds presenting
a confused mass of boarty crystals, rounded and amorphous masses,
or a hard black form of carbonado.

Again, diamond crystals are almost invariably perfect on all sides.
They show no irregular side or face by which they were attached
to a support, as do artificial crystals of chemical salts; another
proof that the diamond must have crystallised from a dense liquid.

When raised the diamond is in a state of enormous strain, as
I have already shown by means of polarised light. Some diamonds
exhibit cavities which the same test proves to contain gas at
considerable pressure.

The ash left after burning a diamond invariably contains iron as
its chief constituent ; and the most common colours of diamonds, when
not perfectly pellucid, show various shades of brown and yellow, from
tbe palest "off colour" to almost black. These variations accord
with the theory that the diamond has separated from molten iron,
and also explain how it happens that stones from different mines,
and even from different parts of the same mine, differ from each
other. Along with carbon, molten iron dissolves other bodies
which possess tinctorial powers. One batch of iron may contain an
impurity colouring the stones blue, another lot would tend towards
the formation of pink stones, another of green, and so on. Traces of
cobalt, nickel, chromium and manganese, metals present in the blue
ground, might produce all these colours.

A hypothesis, however, is of little value if it only elucidates
one-half of a problem. Let us see how far we can follow out the
ferric hypothesis to explain the volcanic pipes. In the first place we
must remember these so-called volcanic vents are admittedly not
filled with the eruptive rocks, scoriaceous fragments, &c., constituting
the ordinary contents of volcanic ducts. At Kimberley the pipes are
filled with geological plum pudding of heterogeneous character —
agreeing, however, in one particular. The appearance of shale and

25- — Diamonds in Rontgen Rays.

A.— Black Diamond (in Gold Frame),
B. — Glass Imitation Diamond.
C— Pink Delhi Diamond.

26.— Artificial Diamond, from Molten Iron.

-Artificial Diamond from Molten Iron.

28. — Diamond Crystal in the form of a Drop.

1897.] on Diamonds. 497

fragments of other rocks shows that the melange has suffered no
great heat in its present condition, and that it has been erupted from
great depths by the agency of water vapour or some similar gas.
How is this to be accounted for ?

It must be borne in mind I start with the reasonable supposition
that at a sufficient depth * there were masses of molten iron at a
great pressure and high temperature, holding carbon in solution,
ready to crystallise out on cooling. In illustration I may cite the
masses of erupted iron in Greenland. Far back in time the cooling
from above caused cracks in superjacent strata through which water f
found its way. On reaching the iron the water would be converted
into gas, and this gas would rapidly disintegrate and erode the
channels through which it passed, grooving a passage more and
more vertical in the endeavour to find the quickest vent to the
surface. But steam in the presence of molten or even red-hot iron
rapidly attacks it, oxidises the metal and liberates large volumes of
hydrogen gas, together with less quantities of hydrocarbons J of
all kinds — liquid, gaseous and solid. Erosion commenced by steam
would be continued by the other gases, and it would be no difficult
task for pipes, large as any found in South Africa, to be scored out
in this manner. Sir Andrew Noble has shown that when the screw
stopper of his steel cylinders in which gunpowder explodes under
pressure is not absolutely perfect, gas finds its way out with a rush
so overpowering as to score a wide channel in the metal; some of
these stoppers and vents are on the table. To illustrate my argu-
ment Sir Andrew Noble has been kind enough to try a special
experiment. Through a cylinder of granite is drilled a hole 0 • 2 inch
diameter, the size of a small vent. This is made the stopper of an
explosion chamber, in which a quantity of cordite is fired, the
gases escaping through the granite vent. The pressure is about
1500 atmospheres, and the whole time of escape is less than half a
second. Notice the erosion produced by the escaping gases and by
the heat of friction, which have scored out a channel over half an
inch diameter and melted the granite along their course. If steel and
granite are thus vulnerable at comparatively moderate gaseous pres-
sure, is it not easy to imagine the destructive upburst of hydrogen and
water gas grooving for itself a channel in the diabase and quartzite,
tearing fragments from resisting rocks, covering the country
with debris, and finally at the subsidence of the great rush, filling
the self-made pipe with a water-borne magma in which rocks,

* The requisite pressure of fifteen tons on the square inch would exist not
many miles beneath the surface of the earth,

t There are abundant signs that a considerable portion of tliis part of Africa
was once under water, and a fresh-water shell has been found in apparently
undisturbed blue ground at Kimberley.

X The water sunk in wells close to the Kimberley mine is sometimes impreg-
nated with paraffin, and Sir H. Roscoe extracted a solid hydrocarbon from the
"blue ground."

498 Mr. William CrooJces [June 11,

minerals, iron oxide, shale, petroleum and diamonds are churned
together in a veritable witch's cauldron? As the heat abated the
water vapour would gradually give place to hot water, which, forced
through the magma, would change some of the mineral fragments
into the now existing forms.

Each outbreak would form a dome-shaped hill, but the eroding
agency of water and ice would plane these eminences until all traces
ot the original pipes were lost.

Actions such as I have described need not have taken place
simultaneously. As there must have been many molten masses of
iron with variable contents of carbon, different kinds of colouring
matter, solidifying with varying degrees of rapidity, and coming in
contact with water at intervals throughout long periods of geologi-
cal time — so must there have been many outbursts and upheavals,
giving rise to pipes containinn diamonds. And these diamonds, by
sparseness of distribution, crystalline character, difference of tint,
purity of colour, varying hardness, brittleness and state of tension,
would have impressed upon them, engraved by natural forces, the
story of their origin — a story which future generations of scientific
men may be able to interpret with greater precision than we can
to-day.

Who knows but that at unknown depths in the earth's metallic
core beneath the present pipes there are still masses of iron not yet
disintegrated and oxidised by aqueous vapour — masses containing
diamonds, unbroken and in greater profusion than they exist in the
present blue ground, inasmuch as they are enclosed in the matrix
itself, undiluted by the numerous rock constituents which compose
the bulk of the blue ground ?

If this be the case a careful magnetic survey of the country round
about Kimberley might prove of immense interest, scientific and
practical. Observations, at carefully selected stations, of the three
magnetic elements — the horizontal component of direction, the vertical
component of direction and the magnetic intensity — would soon show
whether any large masses of iron exist within a certain distance of the
surface. It has been calculated that a mass of iron 500 feet in
diameter could be detected were it ten miles below the surface. A
magnetic survey might also reveal other valuable diamantiferous
pipes, which owing to the absence of surface indications would
otherwise remain hidden.

There is another diamond theory which appeals to the fancy. It
is said that the diamond is a direct gift from Heaven, conveyed to
earth in meteoric showers. The suggestion, I believe, was first
broached by A. Meydenbauer,* who says : — " The diamond can only
be of cosmic origin, having fallen as a meteorite at later periods of
the earth's formation. The available localities of the diamond
contain the residues of not very compact meteoric masses which may,

* ' Chemical News,' vol. Ixi. p. 20f). 1 890.

1897.] on Diamonds. 499

perhaps, have fallen in historic ages, and which have penetrated
more or less deeply, according to the more or less resistant char-
acter of the surface where they fell. Their remains are crumbling
away on exposure to the air and sun, and the rain has long ago
washed away all prominent masses. The enclosed diamonds have
remained scattered in the river beds, while the fine light matrix has
been swej)t away."

According to this hypothesis, the so-called volcanic pipes are
simply holes bored in the solid earth by the impact of monstrous
meteors — the larger masses boring the holes, while the smaller
masses, disintegrating in their fall, distributed diamonds broadcast.
Bizarre as such a theory may appear, I am bound to say there are
many circumstances which show that the notion of the Heavens
raining diamonds is not impossible.

In 1846 a meteorite fell in Hungary (the " Ava meteorite")
which was found to contain graphite in the cubic crystalline system.
G. Rose thought this cubic graphite was produced by the transfor-
mation of a diamond. Long after this prediction was verified by
Weinschenk, who found transparent crystals in the Ava meteorite.
Mr. Fletcher has found in two meteoric irons — one from Youndegin,
East Australia, and one from Crosby's Creek, United States —
crystals absolutely similar to those in the Ava meteorite.

In 1880 a meteoric falling in Russia contained, besides other
constituents, about 1 per cent, of carbon in light grey grains, having
the hardness of diamond, and burning in oxygen to carbonic acid.

Daubree says the resemblance is manifest between the dia-
mantiferous earth of South Africa and the Ava meteorite, of which
the stony substance consists almost entirely of peridot. Peridot
being the inseparable companion of meteoric iron, the presence of
diamonds in the meteorites of Ava, of Youndegin, and of Crosby's
Creek, bring them close to the terrestrial diamantiferous rocks.

Hudleston maintains that the bronzite of the Kimberley blue ground
is in a condition much resembling the bronzite grains of meteorites ;
whilst Maskelyne says that the bronzite crystals of Dutoitspan
resemble closely those of the bronzite of the meteor of Breitenbach,
but are less rich in crystallographic planes.

But the most striking confirmation of the meteoric theory comes
from Arizona. Here, on a broad open plain, over an area about five
miles diameter, were scattered one or two thousand masses of metallic
iron, the fragments varying in weight from half a ton to a fraction
of an ounce. There is little doubt these masses formed part of a
meteoric shower, although no record exists as to when the fall took
place. Curiously enough, near the centre, where most of the
meteorites have been found, is a crater with raised edges three-
quarters of a mile in diameter, and about 600 feet deep, bearing
exactly the appearance which would be produced had a mighty mass
of iron or falling star struck the ground, scattered in all directions,
and buried itself deep under the surface. Altogether ten tons of

500 Mr. WiJliam Croolces [June 11,

this iron have already been collected, and specimens of the Canyon
Diablo meteorite are in most collectors' cabinets.

An ardent mineralogist, the late Dr. Foote, in cutting a section
of this meteorite, found tlie tools were injured by something vastly
harder than metallic iron, and an emery-wheel used in grinding the
iron had been ruined. He examined the specimen chemically, and
soon after announced to the scientific world that the Canyon Diablo
meteorite contained black and transj^aient diamonds. This startling
discovery was afterwards verified by Professors Friedel and Moissan,
who found that the Canyon Diab'o meteorite contained the three
varieties of carbon — diamond (transparent and black), gra23hite and
amorphous carbon. Since this revelation, the search for diamonds
in meteorites has occupied the attention of chemists all over the
world.

I am enabled to show you photographs of true diamonds I myself
have extracted from pieces of the Canyon Diablo meteorite (Figs. 29,
30), five pounds of which I have dissolved in acids for this purpose
— an act of vandalism in the cause of science for which I hope
mineralogists will forgive me. A very fine slab of the meteorite,
weighing about seven pounds, which bus escaped the solvent, is on
the table before you.

Here, then, we have absolute proof of the truth of the meteoric
theory. Under atmospheric influences the iron would rapidly oxidise
and rust away, colouring the adjacent soil with red oxide of iron.
The meteoric diamonds would be unaffected, and would be left on
the surface of the soil to be found by exj^lorers when oxidation had
removed the last proof of their celestial origin. That there arc still
lumps of iron left at Arizona is merely due to the extreme dryness of
the climate and the comparatively short time that the iron has been
on our i)lanet. We are here witnesses to the course of an event which
may have happened in geologic times auy where on the earth's
surface.

Although in Arizona diamonds have fallen from above, confounding
all our usual notions, this descent of precious stones seeius what is
called a freak of Nature lather than a normal occurrence. To the
modern student of science there is no great difference between the
composition of our earth and that of extra-terrestrial masse«. The
mineral peridot is a constant extra-terrestrial visitor, present in most
meteorites. And yet no one doubts that peridot is also a true con-
stituent of rocks formed on this earth. The spectroscope i ^eals thafc
the elementary composition of the stars and the earth are ^ '^^ much
the same ; so does the examination of meteorites. Inde». only

are the selfsame elements present in meteorites but they arj combined
in the same way to form the same minerals as in the rust of the
earth.

This identity between terrestrial and extra-terrestrial rocks
recalls the masses of nickeliferous iron of Ovifak. Accompani( d with
graphite they form part of the colossal eruptions which have covered

2g. — DiaiTKjnd from Canyon Diablo Meteorite.

50. — Diamond from Canvon Diablo Meteorite.

189'^.] 071 Liamonds. 501

a portion of Greenland, They arc so like meteorites that at first
they were considered to be meteorites till their terrestrial origin was
proved. They contain as much as 1 • 1 per cent of free carbon.

It is certain from observations I made at Kimberley, corroborated
by the experience gained in the laboratory, that iron at a high tem-
perature and under great pressure will act as the long sought solvent
for carbon, and will allow it to crystallise out in the form of diamond
— conditions existent at great depths below the surface of tlie earth.
But it is also certain, from the evidence afforded by the Arizona and
other meteorites, that similar conditions have likewise existed among
bodies in space, and that a meteorite, freighted with its rich contents,
on more than one occasion has fallen as a star from the sky. In
short, in a physical sense, Heaven is but another name for Earth, or
Earth for Heaven.

[W. C]

Vol. XV. (No. 91.)

li L

502 General MontMij 3Ieeting. [June 14,

GENERAL MONTHLY MEETING.

Monday, June 14, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The following Vice-Presidents for the ensuing year were an-
nounced : —

Sir Frederick Abel, Bart. K.C.B. D.C.L. LL.D. F.R.S.

The Right Hon. A. J. Balfour, M.P. D.C.L. LL.D. F.R.S.

William Crookes, Esq. F.R.S.

Edward Fraukland, Esq. D.C.L. LL.D. F.R.S.

Ludwig Mond, Esq. Ph.D. F.R.S.

Basil Woodd Smith, Esq. F.R.A.S. F.S.A.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer.

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Hon. Secretary.

Tempest Anderson, M.D. B.Sc.
Samuel Pope, Esq. Q.C.
Major Clifford Probyn,
were elected Members of the Royal Institution.

The following Address to the Queen was read, and it was moved
from the Chair, seconded by the Honorary Secretary, and carried by
acclamation, all present standing,

" That this Address be approved and authorised to be signed by
His Grace the President on behalf of the Members : —

To Her Most Gracious Majesty the Queen,
Patron of the Eoyal Institution of Great Britain.

May it Please Your Majesty,

We, the President and Members of the Royal Institution of Great Britain, in
general meeting assembled, desire humbly to congratulate your Majesty on the
completion of the Sixtieth Year of your glorious and beneficent reign, and with
profound thankfulness to acknowledge the blessings which we, in common with
all classes of your subjects, have enjoyed under your rule, and more especially, the
freedom and encouragement given to those pursuits with which we, as a corpora-
tion, are concerned.

Science, Arts, and Manufactures, which it is the object of our institution to
promote, have found in the serenity, which your just and gentle government has
conferred upon the country, the conditions most favourable to their growth, while
the ethical principles, which ought ever to sustain and direct these, have been
quickened by the virtues which Ijave adorned your throne. The extension of
education, and particularly of that technical education, the national importance
of which your late illustrious and ever lamented Consort was the first to recognise,
has favoured the diiFusion of natural knowledge, which again has multiplied
useful raeclianical inventions, and conduced to new applications of the mineral
and other productions of the country.

3 897.] General Monthly Meeting. 503

We venture to believe that the investigations carried on in the laboratories
of our Institution during the last sixty yt-ars, by its eminent Professors, have
resulted in discoveries which will make your reign memorable in the annals of
science, and we confidently anticipate that the addition recently made to the
resources of the Institution, l>y the generosity of one of your subjects, will greatly
enhance its public usefulness in the future.

We fervently hope and pray that your Majesty will still, for many years to
come, reign over us and the vast and varied Empire tiiat is happily united under
your Sceptre, and that to-day, with one voice, offers you its grateful homage ; and
we look to a continuance of the gracious patronage, which you and tlie Eoyal
Family have so long bestowed on our Institution, as the best guarantee of its
prosperity and success."

The Presents received since the last Meeting were laid on tlie
table, and the thanks of the Members returned for the same, viz. : —

The Lords of the Admiralty — Report of the Astronomer Royal to the Board of

Visitors, fol. 1897.
Report of Her Majestv's Astronomer at the Cape of Good Hope for 1897.

4to. 1S97.
Independent Day-Numbers for 1897, as used at the Royal Observatory, Cape

of Good Hope. 8vo. 1897.
The Secretary of State for India — Progress Report of the Archfeological Survey

of Western India for Sept. 1895 to April 189(j. fol. 1896.
Palaeontologia Indica. Ser. XVI. Baluchistan and N.W. Frontier. Vol. I.

Tlie Jurassic Fauna. Part 1, The Fauna of the Killaways of Mazar Drik.

Bv F. Noetling. fol. 1895.
Men'ioirs, Vols. XXV. XXVI. 8vo. 1895-96.
Aecademia dei Lincei, Reale, Roma — Atti, Serie Quinta : Rendiconti. Classe di

Scienze Morali, Vol. VI. Fasc. 2. Classe di Scienze Fisiche, etc. 1^ Semes-

tre. Vol. VI. Fasc. 8-10. 8vo. 1897.
American Academy of Arts and Sciences — Proceedings, Vol. XXXII. Nos. 5-9.

8vo. 1897.
Armstrong, Lord, CB. F.R S. M.R.I, (the Author)— "El ecliic Movement in Air

and Water, with Theoretical Inferences, fol. 1897.
Asiatic Societij of Bengtd-FroceeiMn^rs, 189G, Nos. 6-10. 8vo. 1896-97.

Journal, Vol. LXV. Part 1, Nos. 3, 4; Part 2, Nos. 3, 4; Part 3. No. 1. 8vo.

1896-97.
Astronomical Society, Royal— '^lov.thly Notices, Vol. LVII. No. 6. 8vo. 1897.
Banhers, Institute o/— Journal, Vol. XVIIi. Part 5. 8vo. 1897.
Batavia, Magneticul and Meteoroloijical Observatory — Observations, Vol. XVIII.

(1895). 4to. 1896.
Rainfall in tlie East Indian Archipelago (1895). 8vo. 1896.
Berlin, Koniglich Freusnsche Ahademie der Wissenschaften — Sitzungsberichte,

1897. Nos. 1-25. 8vo.
Boston, U.S.A. Puhlic Library — Monthly Bulletin of Books added to the

Library, Vol. II. No. 5. 8vo. 1897.
Boston Society of Natural History — Proceedings, Vol. XXVII. No. 14. 8vo.

1897.
Botanic Society, Uoyal — Quarterly Record, No. 69. 8vo. 1897.
British Architect)*, Royal Institute o/— Journal. 1896-97, Nos. 13, 14. 8vo.
British Astronomical Association — Journal, Vol. VII. No. 6. 8vo. 1897.
British Institute of Public Bealth—Jouvual of State Medicine, Vol. V. No. 1.

8vo. 1897.
British Museum Trustees — Subject Index of Modern Works added to the liibrary

of the British Museum iii tiie years 1885-90 and 1891-95. Compiled by

G. K. Fortescue. 2 vols. 8vo. " 1891 97.

2 L 2

604 General Monthly Meeting. [June 14,

Brymner, Douglas, Esq. LL.D. F.R.S.C. (the Arc1nvist)~'Re\)ort on Canadian

Archives for 1896. 8vo. 1897.
California, University of — Report of Work of the Asciicultural Experiment Stations
of the Univeisity of California for 1894-95. ''8vo. 1896.
Agricultural Experiment Station Bulletins.
Eeport of the Viticultural Work of the Agricultural Experiment Station,

1887-93. 8vo. 1896.
Notes on Cliildren's Drawings. Edited by G. E. Brown. (Univ. of Cal. Studies,

Vol. II. No. 2.) 8vo. 1897.
Geological Bulletins, Vol. I. Nos. 12-14. 8vo. 1896.
Biennial Report of the President of the Universitv, 1894-96. 8vo, 1896.
Reirister of the University, 1895-96. 8vo.
Quiclcsilver Condensation at New Almaden, Cal. By S. B. Christy. Svo.

18S5.
On the Correlation of Elementary Studies. By G. H. Hoursou. Svo. 1896.
Grape Sugar 8vrup. Svo. 1893.
Tlie White Wine Problem. Svo. 1895.
The Vine in Southern California. Svo. 1892.
The Vineyards in Alamede County. Svo. 1893.
The Vineyards of Southern California. Svo. 1888.
Annual Report of the Viticultural Commissioners. 1887. Svo. 1888.
Study of Human Foods and Practical Dietetics. By M. E. Jaffa. Svo. 1S96.
Canadian Institute — Proceedings, New Series, Vol. I. Pari" 1, No. 1. Svo. 1897.
Canning, Hon. A. 8. G. (the Author) — Historv in Fact and Fiction. A Literary

Sketch. Svo. 1897.
Carruthers, Rev. G. T. (the Author) — The Origin of the Celestial Laws and Motions.

Svo. 1897.
Chemical Industry, Society o/^Journal, Vol. XVI. No. 4. Svo. 1897.
Chemical Society — Journal for May, 1897. Svo.

Proceedings, Nos. 179, ISO. Svo. 1897.
Chicago Academy of Sciences — Twenty-ninth Annual Report for 1896. Svo. 1897.
The Lichen Flora of Chicago and Vicinity. By W. W, Calkins. (Bulletin of
Geological and Natural History Survey, No, 1.) Svo. 1896.
Chicaqo Field Columbian Museum — Contribution (2) to the Coastal and Plain
Flora of Yucatan. By C. F. Millspaugh. (Botanical Series, Vol. I. No. 3.)
Svo. 1896.
Catalogue of a Collection of Birds obtained bv the Expedition into Somali-land.
By D. G. Elliot. (Ornithological Series, Vol. I. No. 2.) Svo. 1897.
Cracovie, VAcadimie des Sciences — Bulletin International, 1897, No. 3. Svo.
Crauford and Balcarres, The Right Hon. the Earl of. K.T. F.R.S. i¥.E. J.— Biblio-
theca Lindesiana. First Revifion. Hand List of Proclamations, Vol. II.
George I.-Wil!iam IV. 1714-1837. (Privately Printed at the Aberdeen
University Press.) fol. 1897.
Dissett, 31. R. Esq. (the Author) — The Explanation of the Origin of Solar and
Stellar Light, and the Minor Phenomena connected therewith. Svo. 1897.
Edinburgh, Ttoyal College of Physicians — Reports from the Laboratory, Vol. VI.

Svo. 1897.
Editors — American Journal of Science for May, 1897. Svo.
Analyst for May, 1897. Svo.

Anthony's Photographic Bulletin for May, 1897. Svo.
Aeronautical Journal for April, 1897. Svo.
Astrophysical Journal for May, 1897. Svo.
Athenaeum for Mav, 1897. 4to.
Author for May, 1897.
Bimetallist for May, 1897.
Brewers' Journal for May, 1897. Svo.
Chemical News for May, 1897. 4to.
Chemist and Druggist for May, 1897. Svo
Education 'for May, 1897. Svo.

4897.] General MontUy Meeting. 505

Editors — continued.

Electrical Engineer for May, 1897. fol.

Electrical Engineering for May, 1897.

Electrical Review for May, 1897. 8vo.

Engineer for May, 1897. fol.

Engineering for May, 1897. fol.

Homceopatliic Review for May, 1897.

Horological Journal for May, 1897. 8vo.

Industries and Iron for May, 1897. fol.

Invention for May, 1897. 8vo.

Journal of Physical Chemistry, Vol. I. No. 8. 8vo. 1897.

Journal of State Medicine for May, 1897. 8vo.

Law Journal for May, 1897. 8vo.

Machinery Market for May, 1897. 8vo.

McClure's Magazine for May, 1897. 8vo.

Nature for May, 1897. 4to.

New Book List for IVIay, 1897. 8vo.

New Church Magazine for May, 1897. 8vo.

Nuovo Cimento for April, 1897. 8vo.

Physical Review for May- June, 1897. 8vo.

Science Siftings for May, 1897. 8vo.

Travel for May, 1897.

Tropical Agriculturist for May, 1897. 8vo.

Zoophilist for May, 1897. 4to.
Eynigranis^ Information Office — Combined Circulars for Canada, the Australian

and South African Colonies, Nus. 1-3. 8vo. 1897.
Electrical Engineers, Inxtitution o/— Journal, Vol. XXVI. No. 128. Svo. 1897.
Essex County Technical Laboratories, Chelmsford — Journal for March- April, 1897.

Svo.
Florence, Biblioteca Nazionale Centrale — Bollettino, Nos. 273, 274. Svo. 1897.
Franklin Institute — Journal for May, 1897. Svo.
Geddes, T. E. Esq. — La Resurreccion de Jesu-Christo, Nuestro Seuor. Svo.

Valparaiso, 1896.
Geographical Society, Royal — Geographical Journal for May, 1897. Svo.
Geological Society — Quarterly Journal, No. 210. Svo. 1897.

General Index to Vols. I.-L. of the Quarterly Journal, Part 2, La-Z. Svo.
1897.
Imperial Institute — Imperial Institute Journal for May, 1897.
Johns Hopkins University — University Circulars, No. 129. 4to. 1897.

American Journal of Philology, Vol. XVII. No. 4. Svo. 1896.

American Chemical Journal for May, 1897.
Kew Observatory — Report for 1896. Svo. 1897.

Description of the Kew Observatory.
Leicester Free Public Libraries Committee — Twenty-sixth Annual Report, 1896-

97. Svo.
Life-Boat Institution, Boyal National — Annual Report for 1897. Svo.
London County Council technical Educat on Board — London Technical Educa-
tion Gazette for May, 1897. Svo.
Manchester Geological /Soc/ef?/— Transactions, Vol. XXV. Parts 4-6. Svo. 1897.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Vol.

XLE. Part 3. Svo. 1897.
Massachusetts Institute of Technology— Technology Quarterly, Vol. X. No. 1.

Svo 1897.
Jiuxirxi, Sociedad Cientifica ^'■Antonio Alzate" — Memorias y Revista, Tomo X.

JN^os- 1-4. Svo. 1896-97.
Micro,sco)dcal Society, Boyal - Journal, 1897, Part 2. Svo.

Munick Royal Bavarian Academy of Sciences — Sitzungsberichte, 1896, Heft 3, 4.
Svo 1897.

Ludwig Otto Hesse's Gesammelte Worke. Herausgegeben von d. Math. Ph\ s.
Cla&se d. k. Bayerischen Akad. d Wisoenschaften. 4to. 1897.

506 General Monthly Meeting. [June 14,

Navy League— 'N&vy League Journal for May, 1897. 4to.

Neto York Academy of Sciences — Transactions, Vol. XV. 1895-96. 8vo. 1896.

Annals, Vol. IX. Nos. 4, 5. 8vo. 1897.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLVI. Part 3. 8vo. 1897.
Numismatic Society — Numismatic Chronicle, 1897, Part 1. 8vn.
Odontolvgical Society of Great Britain — Transactions, Vol. XXIX. No. 7. 8vo.

1897.
Onnes, Prof. Br. H. Kamerlingh — Communications from the Physical Laboratory

at the' University of Leiden, No. 2.5. 8vo. 1897.
Faris, Society Frangaise de Physique — Bulletin, Nos. 95-97. 8vo. 1897.

Seances, 1895, Fasc. 1, 2. 8vo. 1895.
Pharmacevtical Society of Great Britain — Journal for May, 1897. 8vo.
Philadelphia Academy of Natural Sciences — Proceedings, 1896, Part 3. 8vo.

1897.
Photoqra'phic Society of Great Britain, Royal — The Photographic Journal for

April-May, 1897. 8vo.
Physical S(dety of London — Proceedings Vol. XV. Part 5. 8vo. 1897.
Rome, Ministry of Public IFor^s —Giornale del Genio Civile, 1897, Fasc. 1°, 2°.

And Designi. fol.
Royal Engineers, Corps of — Professional Papers, Foreign Translation Series,

Vol. i. Nos. 4, 5. 8vo. 1897.
Professional Papers of the Corps of Royal Engineers, Vol. XXII. 8vo. 1896.
Royal Society of Edinburgh — Proceedings, Vol, XXI, No. 4. 8vo. 1897.
Royal Society of London — Philosophical Transnctions, Vol. CLXXXVIII. B.

Nos. 144, 145; Vol, CLXXXIX. A, Nos. 193-196. 4to. 1897.
Proceedings, Nos. 371-373. 8vo. 1897.
Russell, The Hon. F. A. Rullo, F.R.Met.Soc. M.R.I. {the Author)— T:hQ Atmosphere

in relation to Human Life and Health. (Smithsonian Miscellaneous Collec-
tions, No. 1072, Hodgkins Prize Essay.) Washington. 8vo. 1896.
Selborne Society — Nature Notes for INIay, 1897. 8vo.

Smith, Miss Oioen — Fallacies of Race Theories as applied to National Character-
istics. By W. D. Babington. 8vo. 1895.
Smithsonian Institution — Atmospheric Actinometry and the Actinic Constitution

of the Atmo.-phere. (Hodgkins Prize Essay, Smith. Cent, to Knowledge,

No. 103i.) 4to. 1896.
Virginia Cartography : A Bibliographical Description. By P. L. Phillips.

(Smith. Misc. Coll. 1039.) 8vo. 1896.
The Atmosphere in relation to Himian Life and Health. By F. A. R. Eussell.

(Smith. Misc. Coll. 1072.) 8vo. 1896.
Constants of Nat-ire, Part 5. By F. W. Clarke. (Smith. Misc. Coll.

1075.)
Air and Life. By H. De Varginy. (Hodgkins Prize Essay, Smith. Misc. Coll.

1071.) 8vo. 1896.
Mountain Obsi rvatories in America and Europe. By E. S. Holden. (Smith.

Misc. Coll. 1035.) 8vo. 1896.
Smithsonian Physical Tables. By T. Gray. (Smith. Misc. Coll. 1038.) 8vo,

1896.
The Air of Towns. By Dr. J. B. Cohen. (Hodgkins Prize Essay, Smith.

Misc. Coll. 1073.) 8vo. 1896.
Equipment and Work of an Aero-Physical Observatory. By A. McAdie.

(Hodgkins Prize E^say, Smith. Misc.* Coll. 1077.) 8vo. 1897.
Society of Arts — Journal tor May, 1897. 8vo.
St. Bartholomew's Hospital—Yieports, Vol. XXXII. 8vo. 1897.
Sunday Lecture Society— The Sunday Bill of 1895. By A. V. F. Wild. 8vo.

1897.
Tacchini, Prof. Hon. Mem. R.L (the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXVI. Disp. 1, 2. 4to. 1897.
United States Department of Aip-iculture — Experiment Station Bulletin, No. 40.

8vo. 1897.

1897.] General Monthly Meeting, 607

United States Department of Interior (Census Office) — Report on Crime, Pauperism

and Benevolence in the U.S. at the Eleventh Census, 1890, Part 1, Analysis.

4to. 1896.
Eeport on Insurance Business at Eleventh Census, 1890, Part 2, Life Insurance.

4to. 1895.
' Report on Vital and Social Statistics at Eleventh Census, Part 2, Vital

Statistics; Part 4, Statistics of Deaths. 4to. 1895-96.
Report on the Insane, Feeble-minded, Deaf and Dumb and Blind at the

Eleventh Census. 4to. 1895.
• Report on Farms and Homes, Proprietorship and Indebtedness at the Eleventh

Census. 4to. 1896.
United Service Institution, Royal — Journal for May, 1897. 8vo.
United States Patent O^^ce— Official Gazette, Vol. LXXVIII. Nos. 8-13 ; Vol.

LXXXIX. Nos. 1, 2. 8vo. 1897.
Alplabetical List of Patentees and Inventions to Sept. 1896. 8vo.
University College — Supplement to the Catalogue (1879) of the General Library

and South Library of University College. 8vo. 1897.
Upsal, Observatoire Meteorologique — Bulletin Mensuel, Vol. XXVIII. 4to.

1896-97.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1897,

Heft 4. 4to.
Vienna, Geological Institute, Imperial — Jahrbuch, Band XL VI. Heft 2. 8vo.

1897.
Williams and Norgate, Blessrs. (the Publishers) — Problems of Nature : Researches

and Discoveries of Gustav Jaeger. Edited and Translated by H. G.

Schlichter, 8vo. 1897.
Yorkshire Philosophical Society — Annnal Report for 1896. 8vo. 1897.
Young & Co. Messrs. D. (the Publishers) — The Inventor's Companion. 8vo. 1897.
Zoological Society of London — Report of the Council for 1896. 8vo. 1897.
Zurich, Naturforschende Gesellschaft — Vicrteljahrsschrift, 1897, Heft 1. 8vo.

508 General Monthly Meeting. [July 5,

GENERAL MONTHLY MEETING,

Monday, July 5, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.E.S. Treasurer and
Vice-President, in the Cliair.

Hugh Harper Baird, Esq.

Ivon Braby, Esq.

James Mackenzie Davidson, Fsq, M.B. CM.

Axfchur Croft Hill, Esq. B.A.

James Y. Johnson, Esq.

Leo Kamm, Esq.

Michael Edmund Stephens, Esq.

The Rev. Henry Wace, D.D.

Julius Wernher, Esq.

Henry Wilde, Esq. E.R.S.

were elected Members of the Royal Institution^

The Special Thanks of the Members were returned for the following
Donation to the Fun^^ for the Promotion of Experimental Research at
Low Temperatures:—

Sir Andrew Noble, K.C.B. .. .. £100

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FOR

Accademia del Lincei, cttfxU, Homa — Classe di Scienze Fisiche, Matematiche e

Nuturali. Atti, Serie Quinta: Rendiconti. lo iSemestre, Vol. VI. Fasc. llo.

Classe di Scienze Morali, &c. Serie Quinta, Vol. VI. Fasc. 3, 4 8vo. 1897.
Agricultural Society of England, Eoyal — Journal, 3rd Series, Vol. VIII. Part 2.

8vo. 1897.
American Academy of Arts and Sciences — Proceedings, New Series, Vol. XXII.

Nos. 10, 12. Svo. 1.^97.
Astronomical Society, Boyal — Mocthly Xotices, Vol. LVII. Xo. 7. Svo. 1897.
Bankers, Institute o/— Journal, Vol, XVIII. Part 6. Svo. 1897.
Bech, M. J/, {the Author) — Etude expe'rimentale sur rElectro-Magne'tisme ren-

versant toutes les ide'es actuellenient admises sur cette science. Svo. 1897.
Boston Public Library— Monthly Bulletin, Vol. II. No. 6. Svo. 1897.
British Architects, Eoyal Institute of — Journal, 3rd Series, Vol. IV. Nos. 15, 16.

4to. 1897.
British Astronomical Association — Journal, Vol. VII. Nos. 7. 8. Svo. 1897.
•Qambrldge Fhilosophical Society — Proceedings, Vol. IX. Part 5. Svo. 1897.
Camera Club — Journal for May-June, 1897. Svo.
Oape of Good Hope, The Surveyor-General of the Colony of the — Report on Colonel

Morris's Geodetic Survey of South Africa. By D. Gill. fol. 1896.
'Chemical Industry, Society of — Journal, Vol. XVI. No. 5. Svo. 1897.
'Chemical Society — Journal lf>r June. 1897. Svo.
ProceedingSv, Nos. 173-178, 181. Svo. 1807.

1897.] General Monthly Meeting. 609

Editors — American Journal of Science for Juno, 1897. 8vo.
Analyst for June, 1897. 8vo.

Anthony's Photographic Bulletin for June, 1897. 8vo.
Aeronautical Journal for January, 1897. Svo.
AtheufBum for June, 1897. 4to.
Author for June, 1897. 8vo.
Bimetaliist for June, 1897.
Brewers' Journal for June, 1897. 8vo.
Chemical News for June, 1897. 4to.
Chemist and Druggist for June, 1897. Svo.
Education for June, 1897.
Electrical Engineer for June, 1 837. fol.
Electrical Engineering for June, 1897. 8vo.
Electrical Review for June, 1897. 8vo.
Electricity for June, 1897. 8vo.
Engineer for June, 1897. fol.
Engineering for June, 1897. fol.
Homoeopathic Review for June, 1897. 8vo,
Horological Journal for June, 1897. Svo.
Industiies and Iron for June, 1897. fol.
Invention for June, 1897.

Journal of Physical Chemistry for June, 1897.
Journal of State Medicine for June, 1897. Svo.
Law Journal for June, 1897. Svo.
Lightning for June, 1897, Svo.

London Technical Education Gazette for June, 1897. Svo.
Machinery Market for June, 1897. Svo.
Nature for June, 1897. 4to.
New Book List for June, 1897. Svo.
New Church Magazine for June, 1897. Svo.
Nuovo Cimento for May, 1897. Svo.
Photographic News for June, 1897. Svo,
Public Health Engineer for June, 1897. Svo.
Science Siftings for June, 1897.
Transport for June, 1897. fol.
Tropical Agriculturist for June, 1897.
Zoophilist for June, 181^7. 4to.
Electrical Engineers, Institution q/"— Journal, Vol. XXV. No. 12'-. Svo. 1897,
Emigrants' Information Office — Combined Circulars for Canada, The Australasian

and South African Colonies, Nos. 1-3. Svo 1897.
Evans, Sir John, K.C.B. F.R.S. ill. i?.Z.— "The Parlement of the Thre Ages.'*

(An alliterative poem of the 14th Century : now first edited from MSS. in

the British Museum, with introduction, notes, and appendices containing'

the poem of " Winnere and Wastoure " and illustrative texts, by I. GoUancz.)

4to. 1897.
Florence, Biblioteca Nazionale Centrale — BoUetino, No. 275. Svo. 1897.
Franklin Institute — Journal for June, 1897. Svo.

Geographical Society, Royal — Geographical Journal for June, 1897. Svo.
Notes of a Journey on the Upper Mekong, Siam. By H. W. Smith. (Extra

Publication.) Svo, 1895.
British New Guinea, Country and People. By Sir W. Macgregor. (Extra

Publication.) Svo. 1897.
Eastern Persian Irak. By General A. Houtum-Schindler. (Extra Publica-

ticm.) Svo. 1897.
Imperial Institute — Imperial Institute Journal for June, 1897.
Johns Hopkins University — American Journal of Philology, Vol. XVIII. No. 1»

Svo. 1897.
American Chemical Journal, \o\. XIX. No, 6 (June). Svo. 1807»
University Circulars, No, 130. Svo. 1897.

610 General Monthly Meeting. [July 5,

Knox. H. T. a Esq. 3I.R.L— The Navy League Guide to the Naval Review of

1897. 8vo. 1897.
Meteorological Society, Royal — Quarterly Journal for April, 1897. Svo.
Meteorological Record, No. 63. 8vo. 1897.

Hints to Meteorological Observers. Fourth edition. Svo. 1897.
Microscopical Society, Royal— Journal, 1897, Part 3, 8vo.
Middlesex Hospital— Reports for 1895. 8vo. 1896.
Navy League — Navy League Journal for June, 1897. Svo.
Paris, Societe Frangaise de Physique — Se'ances, 1896; Fasc. 4.

Bulletin, Nos. 98, 99. Svo. 1897.
Perry- Coste, F. H. Esq. (the Author) — An Extraordinary Case of Colour Blind-
ness. Svo. 1897.
Pharmaceutical Society of Great Britain — Journal for June, 1897. Svo.
Philadelphia, Academy of Natural Sciences — Proceedings, 1897, Part 1. Svo.
Philadelphia, Geographical Society of — Map of the Arctic Regions (with most

recent Explorations). By A. Heilprin. fol. 1897.
Photographic Society, Royal — Pliotographic Journal for June, 1897. Svo.
Physical Society of London — Proceedings, Vol. XV. Part 6. Svo. 1897.
Rome, Ministry of Public Works — Giornale del Genio Civile, 1897, Fiisc. 3. Svo.
Rose & Co. Messrs. W. — Jubilee Souvenir of the Fire Service. A History of the

Fire Service and its Organisations, fol. 1897.
Royal Cormocdl Polytechnic Society — Sixtv-fourtli Annual Report, 1896. Svo.
Royal Society of London — Proceedings, No. 374. Svo. 1897.
Saxon Society of Sciences, Royal —
Ma thematiseh- Physische Ciasse —

Berichte, 1897, Nos. 1, 2. Svo. 1897.
Selborne Society — Nature Notes for June, 1897. Svo.
Society of Arts — Journal for June, 1897. Svo.
St. Petersburg, Academic Imperiale des Sciences — Bulletin, V^ Serie, Tome VI

No. 3. Svo. 1897.
Tacchini, Prof. P. Hon.Mem.R.L (the Author') — Memorie della Societa degli Spet-

troscopisti Italian!, Vol. XXVI. Disp. 3. fol. 1897.
Thornton, James Howard, Esq. C.B. — Memories of Seven Campaigns (India,

China, Egypt, the Soudan). Svo. 1895.
United Service Institution, i?oya/— Journal for June. Svo. 1897,
United States Department of Agriculture — Experiment Station Record, Vol. VIII.

No. 7. Svo. 1897.
Experiment Station Bulletin, No. 38. Svo. 1897.
Cotton Culture in Egvpt. By G. P. Foaden. (Experiment Station Bulletin,

No. 42.) Svo. 1897.
Some Common Birds in their relation to Agriculture. By F. E. L. Beal.

(Farmers' Bulletin, No. 54.) Svo. 1897.
United States Patent O/^icc— Official Gazette, Vol. LXXIX. Nos. 3-6. Svo. 1897.
Upsal, Royal Society of Sciences — Nova Acta, 3rd Ser. Vol. XVII. Fasc. 1. 4to.

1896.
Verein zur Beforderung des Gewerbfieisses in Preussen — Verhandlungen, 1897,

Heft 5. 4to.
Vienna, Imperial Geological Institute — Verhandlungen, 1897, Nos. 6-8. Svo.
Welch, J. Cuthbert, Esq. F.C.S. (the Compiler) — General Index of the Proceedings

of the Societv of Public Analysts. Vol I. and to Tlie Analyst, Vols. I.-XX.

(1877-96). *8vo. 1897.
Zoological Society of London — Proceedings, 1897, Part 1. Svo. 1897.

1897.] . General Monthly Meeting. * 511

GENERAL MONTHLY MEETING,

Monday, November 1, 1897.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

John W. Woodall, Esq. M.A. D.L. J.P.
was elected a Member of the Royal Institution.

The following letter was read : —

Whitehall, 2.nd Juhj, 1897.
My Lord Duke, — I have liad the honour to lay before The Queeu the loyal
and dutiful address of the Eoyal Institution of Grt at Britain on the occasion of
Her Majesty attaining the sixtieth year of her reign, and I have to inform Your
Grace that Her Majesty was pleased to receive the same very graciously.

I have the honour to be,

My Lord Duke,
Your Grace's obedient servant,

(Signed) M. W. Ridley.
His Grace The Duke of Northumberland, K.G., &c.

The^ Special Thanks of the Members were returned to Mr. A. J.
Hipkins for his valuable present of the Collection of Tuning Forks
made by the late Dr. Alexander J. Ellis, F.R.S. 3I.BJ.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FOR

TJie Governor- General of India — Geological Survey of India : Records, Vol. XXX.

Parts 2, 3. 8vo. 1897.
The Lords of the Admiralty — Results of the Spectroscopic and Photographic

Observations made at the Royal Observatory, Greenwich, in 1894. 4to. 1897.
Greenwich Observations for 189-4. 4to. 1897.
Tlie British Museum {Natural if /sior?/)— Catalogue of the Fossil Cephalopoda,

Part 3. By A. H. Ford and G. C. Crick. 8vo. 1897.
Catalogue of the African Plants collected by Dr. F. Welwitsch in 1853-61.

Dicotyledons, Part 1. By W. P. Hiern. 8vo. 1896.
Catalogue of Tertiary Mollusca, Part 1.

The Australian Tertiary Mollusca. By G. F. Harris. 8vo. 1897.
Guide to the Fossil Mammals and Birds. 8vo. 1896.
Guide to the Fossil Reptiles and Fishes. 8vo. 1896.
Guide to the Fos>il Invertebrates and Plants. 8vo. 1897.
Tlie Meteorological Office — Meteorological Observations at Stations of the Second

Order for 1892 and 1893. 4to. 1896-97.
Monthly Cm-rent Charts for the Atlantic Ocean, fol. 1897.
Hourly Means for 1893. 4to. 1896.
Report of the International Meteorological Conference at Paris, 1896. 8vo.

1897.

512 General Montlihj Meeting. [Nov. 1,

Accademia dei Lincei, JReale, Roma — Atti, Serie Quiiita : Eendiconti. Classe di

Scienze Morali, Vol. VI, Fasc. 5, 6. Classe di Scienze Fisiche, etc. 1" Semes-

tre, Vol. VI. Fasc. 12. 2° Semestre, Fasc. 1-7. 8vo. 1897.

Atti deir Accademia Pontificia de' Nuovi Lincei, Anno L. Sess. V*. VP. 4to.

1897.

Adams Memorial Committee — Scientific Papers of J. C. Adams, Vol. I. Edited

by W. G. Adams, with a Memoir by J. W. L. Glashier. 4to. 1896.
Agricultural Society of Great Britain, Boyal — Journal, 3rd Series, Vol. VIII.

Part 3. 8vo. 1897.
American Academy of Arts and Sciences — Proceedings, Vol. XXXII. No. 15. 8vo.

1897.
American Geographical Society — Bulletin, Vol. XXIX. No. 2. 8vo. 1837.
American Philosophical Society — Proceedings, Vol. XXXVI. No. 154. 8vo. 1897.
Amsterdam Royal Academy of Sciences — Jaarboek, 189(J. 8vo. 1897.
Verslaiien, Deel 5. 8vo. 1897.

Verbandelingen, Erste Sectie, Deel V.; Twsede Sectie, Beel II. Deel V.
Nos. 4-10. 8vo. 1896-97.
Arc^toivslii, Henryh (the Author j—IjH Ge'nealogie des Sciences : quelques remarques
sur la Bibliographic des Me'moires scientifiques et le Principe de la
classification des Sciences. 8vo. 1897.
Materiaux pour servir a la Bitjliographie des Travnux scientifiques Polonais
(Index des Me'moires publics dans les premiers Volumes des Mem. Physio-
graphiques de Pologne). 8vo. 1897.
Asiatic Society of Bengal — Proceedings, 1897, Nos. 1-4. 8vo. 1897.

Journal, Vol. LXV. Part 3, Special Number. Vol. LXVI. Part 1, No. 1 ;
Part 2, No. 1. 8vo. 1897.
Anatic Society, Royal — Journal, July-Oct. 1897. 8vo.

Astronomical Society, Royal — Monthly Notices, Vol. LVII. No. 8. 8vo. 1897.
Australian Museum, Sydney — Annual Report of the Trustees for 1896. 8vo.

1897.
Bandsept, M. A. (the Author) — Incandescence par le gaz: Bruleurs ct Manchons.

8vo. 1897.
Banlers, Institute o/"— Journal, Vol. XVIII. Part 7. 8vo. 1897.
Berlin, Konigliche Technische Hochschule — Programm, 1897-9S. 8vo.
Berthot, P. Esq. (the Author) — Des Forces Mutuelles et de leurs applications aux
phenomenes meVaniques, physiques et cliimiques. 2 Parts. 1886-1897.
Sur une loi empirique reliant le rayon moyen orbitaire, la masse et la pesanteur

a I'equateur des planetes. 1896.
Sur les effets des forces mutuelles.
Bevan, Rev. J. 0. M.A. 3LR.I. — An Archaeological Survey of Herefordshire.

Mediaeval Period. By J. Davies and J. O. Bevan. 4to. 1897.
Bhxhely, Mrs. H. C. (the Authoress) — Blakely and Armstrong Guns. Third

edition. 8vo. 1897.
Boston, U.S.A. Public Library — Monthly Bulletin of Books added to the Library.
Vol. IL Nos. 7-10. 8vo. 1897.
Forty-fifth Annual Eeport. 8vo. 1897.

A List of Periodicals, Newspapers, Transactions and other Serial Publications
currently received in the principal Libraries of Boston and Vicinity. 8vo.
1897.
Contributions towards a Bibliography of the Higher Education of Yy^omen.

8vo. 1897. (Bibliographies of Special Subjects, No. 8.)
A Brief Description of the Chamberlain Collection of Autographs in Boston
Public Library. 8vo. 1897.
Botanic Society, Royal — Quarterly Record, No. 70. 8vo. 1897.
British Architects, Royal Institute of — Journal, 1896-97, Nos. 17-20. 8vo.

Calendar, 1897-98. 8vo.
British Astronomical Association — Memoirs, Vol. V. Parts 3, 4. 8vo. 1897.

Journal. Vol. VII. Nos. 9, 10. 8vo. 1897.
Cambridge University Library —Annunl Report of the Library Syndicate. 8vo.
1896.

1397.] General MontJily Meeting. 513

Camera Club — Journal for July-Oct. 1897. 8vo.

Canada, Geological Survey of — Annual Eeport (N.S.) Vol. VIII. (1895) and

Maps. 8vo and fol. 1897.
Chemical Industry, Society of — Journal, Vol. XVI. Nos. 6-9. 8vo. 1897.
Chemical Society — Journal for July-Oct. 1897. 8vo.

Proceedings, No. 182. 8vo. 1897.

List of Fellows, May, 1897. 8vo.
CJiilovi, D. Esq. (the Author) — Cataloj^hi delle Biblioteche e I'lnstituto Inter-

nfizionale di Bibliografia di Bruxelles. 8vo. 1897.
alley, Frank H. Esq. (the Author)— Some Fundamental Propositions relating to

the Design of Frameworks. 8vo. 1897.
Civil Engineers, Institution of — Minutes of Proceedings, Vols. CXXVIII. CXXIX.
8vo. 1897.

Eeport of the Council, 1897. 8vo.
Colonial Institute, i^oyaZ— Proceedings, Vol. XXVIII. 8vo. 1897.
Cracovie, Arademie des Sciences — Bulletin International, 1897, Nos. 4-7. 8v6.
Dax, Societe de Borda — Bulletin, 1896, No. 4. 8vo.

Defonshire Association — Report and Transactions, Vol. XXIX. 8vo, 1897.
East India Association— Journal, Vol. XXIX. Nos. 10, 11. 8vo. 1897.
Edinburgh, Royal Society of — Proceedings, Vol. XXI. No. 5. 8vo. 1896-97.
Editors — American Journal of Science lor July-Oct. 1897. 8vo.

Analyst for July-Oct. 1897. 8vo.

Anthony's Photographic Bulletin for July-Oct. 1897. 8vo.

Aeronautical Journal for July-Oct. 1897. 8vo.

Astrophysical Journal for July-Oct. 1897. 8vo.

Ateneo Veneto for 1896. 8vo.

Athenseum for July-Oct. 1897. 4to.

Author for July-Oct. 1897.

Bimetallist for July-Oct. 1897.

Brewers' Journal for July-Oct. 1897. 8vo.

Chemical News for July-Oct. 1897. 4to.

Chemist and Druggist for July-Oct. 1897. 8vo.

Education for July-Oct, 1897. 8vo.

Electrical Engineer for July-Oct. 1897. fol.

Electrical Engineering for July-Oct. 1897.

Electrical Review for July-Oct. 1897. 8vo.

Engineer for July-Oct. 1897. fol.

Engineering for July-Oct. 1897. fol.

Homceopathic Review for July-Oct. 1897.

Horological Journal for July-Oct. 1897. 8vo.

Industries and Iron for July-Oct. 1897. fol.

Invention for July-Oct. 1897. 8vo.

Journal of Physical Cliemistry for Oct. 1897. 8vo.

Journal of State Medicine for July-Oct. 1897. 8vo.

Law Journal for July-Oct. 1897. ' 8vo.

Machinery Market for July-Oct. 1897. 8vo.

Nature for July-Oct. 1897. 4to.

New Church Magazine for July-Oct. 1897. 8vo.

Nuovo Cimeiito for June-Sept. 1897. 8vo.

Physical Review for July-Sept. 1897. 8vo.

Public Health Engineer for July-Oct. 1897. 8vo.

Science Sittings for July-Oct. 1897. 8vo.

Terrestrial Magnetism for June, 1897. 8vo.

Travel for June and Sept. 1896, March, June and July-Oct. 1897.

Tropical Agriculturist for July-Oct. 1897. 8vo.

Zoophilist for July-Oct. 1897. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXVI. No. 130. 8vo. 1897.

General Rules recommended for the Supply of Electrical Energy. 8vo. 1897.

List of Members, &e. 1897. 8vo.
Ellis, Charles, E-q. (the ^ttfftor)— Shakespeare and the Bible. 16mo. 1896.

514 General Monthly Meeting. [Nov. 1,

Emigrants' Information Office — Canada Circular, 1897. 8vo.
Australasian Colonies Circular, 1897. 8vo.
South African Colonies Circular, 1S97. 8vo.
Essex County Technical Labor atories, Chelmsford — Journal for May- July, 1897.

8vo.
Field Columbian Museum — Archseological Studies among the Ancient Cities of
Mexico, Part 2. By W. H. Holmes. 8vo. 1897.
Observations on Popocatapetel and Ixtaxihuati. By O. C Farriugton.
List of Mammals from Somali land, ^c. By D. G. Elliott. Hvo. 1897.
Florence, Biblioteca]Nazionale Oen^raZt?— Bollettino, Nos. 276-283. 8vo. 1897-
Florence, Reale Accademia dei GeorgafiU — Atti, Vol. XX. Disp. 2. 8vo. 1897.
Franldin Institute — Journal for July-Oct. 1897. 8vo.
Garrard, J. J. Esq {the Author) — Report on the Mining Industry of Zululaud in

1896. 8vo. 1897.
Geographical Society, Royal — Geographical Journal for July-Oct. 1897. 8vo.
Geological Society — Quarterly Journal, No. 211. 8vo. 1897.

Geological Literature added to the Geological Society's Library during year
1896. 8vo. 1897.
Gladstone, Dr. J. H. F.R.S. M.B.I. — Tijdschrift van het Kon. Nederlandsch
Aardrijkskundig Genootscbap v. Amsterdam, Tweede Series, Deel XIIL
8vo. 1896.
Glasgow, Philosophical Society of — Proceedings, Vol. XXVIII. 8vo. 1897.
Harlem, Societe' Hollandaise des Sciences — Archives Ne'erlandaises, Serie II.
Tome 1, Livr. 1. 8vo. 1897.
CEuvres Completes de Christian Huygens. Tome VII. Correspondance, 1670-
1675. 4to. 1897.
Harvard College, Astronomical Observatory — Annals, Vol. XXVI. Part 2. 4to. 1897.
Head, Jeremiah, Esq. M. Inst. C.E. M.B.I, (the Author) — The Coal Industry of the
South-Eastera States of North America. 8vo. 1897. (North of England
Institute of Mining Eng. Excerpt.)
Howard Association — Penological and Preventive Principles. By Wm. Tallack.

Second edition. 8vo. 1896.
Illinois State Laboratory of Natural History — Bulletin, Vol. V. Part 2. 8vo. 1897.
Imperial Institute — Imperial Institute Journal for July-Oct. 1897.
Iron and Steel Institute — Journal, 1897, No. 1. 8vo.

List of Members, 1897.
Japan Imperial University — Journal of the College of Science, Imperial Univer-
sity of Japan, Vol. X. Part 2. 4to. 1897.
Johns HopMns University — University Circulars, No. 131. 4to. 1897.
American Journal of Philology, Vol. XVIII. No. 2. 8vo. 1897.
American Chemical Journal for July, Aug. 1897.
Knox, Miss C. T. F. — Coelum Philosnphorum. 24mo. 1553.
Dictionarium Theophrasti Paracelsi. 16njo. 1584.
Dictionnaire Mytho-Herme'tique. Par H. J. Pernety. 16mo. 1787.
Knox, H. T. C. Esq. M.B.I.—The Navy League Handbook, 1897. 8vo.

The British Navy for 100 years. By C. N. McHardy. 8vo. 1897.
Leeds, Literary and Philosophical Society of — Annual Report. 8vo. 1897.
Life-Boat Imtitution, Boyal National — Journal for Aug. 1897.
Linnean Society — Journal, Nos. 167, 228. 8vo. 1897.

Transactions : Botau}', 2n(l Series, Vol. V. Parts 5, 6 ; Zoology, 2nd Series,
Vol. VI. Parts 7, 8 ; Vol. VII. Parts 1-3. 4to. 1896-97.
Liverpool, Literary and Philosophical Society — Proceedings, Vol. LI. 8vo. 1897.
London Chamber of Commerce — Cement Trade Section— Report re Cement Admix-
ture, with evidence of experts, fol. 1897.
London County Council Technical Education Board — London Technical Educa-
tion Gazette for July-Oct. 1897. 8vo.
Manchester Geological Society — Transactions, Vol. XXV. Parts 7-11. 8vo. 1897.
Manchester Museum, Owens College — Notes from the Manchester Museum. Nos.
1-4. 8vo.
Report for the Year 1896-97. 8vo. 1897.

1897.] General Monthly Meeting. 515

Manchester Steam Users' Association— FovLi'ieenth Annual Report on the Working

of the Boiler Explosions' Acts, 1882-90. Reports, Nos. 878-956. fol. 1896.
Manicini, Diodeziano, Esq. (the Translator) — Odi, Epistole, Satire del Horace.

(In Italian.) 8vo. 1897.
Massachusetts Institute of Technology — Technology Quarterly, Vol. X. Nos. 2, 3.

8vo. 1897.
Mechanical Engineers, Institution of — Proceedings, 1896, No. 3. 8vo. 1897.
Medical and Chirurqiccd Society of London, Royal — Medico-Chirurgical Transac-
tions, Vol. LXXX. 8vo. 1897.
Mersey Commission — Report on the present state of the Navigation of the River

Mersey, 1896. By Sir G. S. Nares. 8vo. 1897.
Meteorological Society, Boyal — Quarterly Journal, No. 103. 8vo. 1897.

Meteorological Record, No. 64. 8vo.' 1897.
Metropolitan Asylums Board — Report for the year 1896. 8vo. 1897.
Microscopical Society, Boyal — Journal, 1897, Parts 4, 5. 8vo.
Montpellier^ Academic des Sciences et Lettres — Memoires, 2^ Ser. Tome II. Nos. 2-4.

8vo. 1895-96.
Munich, Royal Bavarian Academy of Sciences — Sitzungsberichte, 1897, Heft 2.

8vo. 1897.
Musical Association — Proceedings for 1897. 8vo.
Navy League — Navy League Journal for July-Oct. 1 897. 4to.
New Jersey, Geologiccd Survey of — Annual Report for liS96. 8vo. 1897.
New South Wales, Agent-Genral for — Wealtli Progress of New South Wales,

1895-96, Vol. I. 9th issue. 8vo. 1897.
New South Wales, Royal Society of — Journal and Proceedings, Vol. XXX. 8vo.

1897.
New Zealand, Registrar-General of — Report on the Results of a Census of the

Colony of New Zealand taken on April 12, 1896. By E. J. Von Dadelszen.

4to. 1897.
Results of a Census of the Colony of New Zealand taken in 1896. fol. 1897.
Norfolk and Norwich Naturalists' Society — Transactions, Vol. VI. Part 3. 8vo.

1897.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLVI. Parts 4, 5. 8vo. 1897.
Annual Report, 1896-97. 8vo. 1897.
Numismatic Society — Numismatic Chronicle, 1897, Parts 2, 3. 8vo.
Odontological Society of Great Britain — Transactions, Vol. XXIX, No. 8. 8vo.

1897.
Onnes, Prof. Dr. H. JiTajnerZmg^— Communications from the Physical Laboratory

at the University of Leiden, Nos. 32, 34, 35, 37-40. 8vo. 1897.
Paris, Societe Francaise de Pliysique — Bulletin, Nos. 100, 101. 8vo. 1897.

Seances, 1897, Fasc. 1. 8vo.
Pharmaceutical Society of Great Britain — Journal for July-Oct. 1897. 8vo.
Photographic Society of Great Britain, Royal — The Photographic Journal for

July-Sept. 1897. 8vo.
Physical Society of London — Proceedings, Vol. XV. Parts 7-10. 8vo. 1897.
Queensland, Agent-Genercd for — The Work and Wealth of Queensland. 8vo.

1897.
Roberts, Isaac, Esq. D.Sc. F.R.S. (the Author)— A selection of Photographs of

Stars, Star-Clusters and Nebulae, together with information concerning the

Instruments and the methods employed in the pursuit of Celestial Photo-
graphy. 4to. 1893.
Rochechouart, La Societe des Amis des Sciences et Arts — Bulletin, Tome VI. No. 5.

8vo. 1896.
Rome, Ministry of Pxdjlic TFbr/iS— Giornale del Genio Civile, 1897, Fasc. 4-6.

And Dcsigni. fol.
Royal College of Surgeons of England — Calendar for 1897. Svo.
Roycd Horticultural Society — Journal, Vol. XXI. Part 1. 8vo. 1897.
Royal Irish Academy — Proceedings, 3rd Series, Vol. IV. Nos. 2, 3. 8vo.

1897.

516 General Monthly Meeting. [Nov. 1,

Boyal Society of London — Record of the Royal Society. 8vo. 1897.

Philosophical Transactions, Vol. CLXXXVIII. B, No3. 146-149; Vol.

CLXXXIX. A, Nos. 197-206. 4to. 1897.
Proceedings, Nos. 375-379. 1897. 8vo.
Sanitary Institute — Journal for July-Oct. 1897. Svo.
Saxon Society of Sciences, Royal —
Mathematisch- Ph ysische Classe —

Berichto, 1897, No. 3. 8vo. 1897.
PMlologiscli -Historische Classe —

Abhandlungen, Band XVIL No. 6. 8vo. 1897.
Selborne Society — Nature Notes for July-Oct. 1897. 8vo.

Sherhorn, C. B. Esq. F.G.S. F.L.S. (the Autlior)— Books of Reference in the
Natural Sciences. 8vo. 1894.
Explanation of the Atlas adopted for Preparing an Index Generum et Specie-
rum Animalium. 8vo. 1896.
Smithsonian Institution (Bureau of Ethnology)~F onrteenth Annual Report,
Parts 1, 2 ; Fifteenth Annual Report. Svo. 1897.
Report of Board of Regents, 1894-95. 8vo. 1896.
Memoir of G. B. Goode, 1851-96. By S. P. Langley. 8vo. 1897.
Annual Reports of U.S. National Museum for 1893 and 1894. Svo. 1895-96.
Society of Arts — Journal for July-Oct. 1897. Svo.

Report of the Proceedings of the Fourtli Meeting of the International Congress
on Technical Education held in london, June 1897. Svo. 1897.
Statistical Society, Royal — Journal, Vol. LX. Parts 2, 3. Svo. 1897.
St. Bartholomeiv's Hospital— SUitistic&l Tables for 1896. 8vo. 1897.
Swedish Academy of Sciences, Eoycd — Ofversigt (Bulletin), Vol. LIII. Svo. 18J)7.
Handlingar (Memoires), Vol. XXVIII. 4to. 1895-96.
Bihaug, Vol. XXiI. Svo. 1896-97.
Taechini, Prof. P. Hon. Mem. R.I. (the Author) — Memorie della Societa degli

SpettroscopiBti Italian!, Vol. XXVI. Disp. 4-8. 4to. 1897.
Teyhr Museum.— Archives, Se'rie II. Vol. V. Part 3. Svo. 1897.
Toulouse, Societe Archeologique du Midi de la France — Memoires, Tome XV.

Livr. 2. 4to. 1896.
United Service Institution, Royal — Jouri al f >r July-Oct. 1897. Svo.
United Sta^-'s Department of Agriculture — Experiment Station Record, Vol. VIII.
Nos. S-il; Vol. IX. ^o. 1. Svo. 1897.
Year Book, 1896. Svo. 1897.
United States latent 0^'ce— Official Gazette, Vol. LXXIX. Nos. 7-13; Vol.
LXXX. No. 1. Svo. 1897.
Alphabetical List of Patentees and Inventions to Dec. 1896. Svo.
University of London — Calendar for 1897-98, and Revised Regulations for 1S99.

Svo. 1897.
Verein zur Beforderung des Gewerhjleisses in Preussen — Verliandlungen, 1897,

Heft 6-10. 4to.
Victoria JwsfiYufe— Journal of the Transactions, Vol. XXIX. Nos. 1 13, 114. Svo.

1897.
Vienna, Geological Institute, Imverial — Jahrbuch, Band XLVI. Heft 3, 4; Baud

XLVII. Heft 1. Svo. 1897.
Waller, Professor A. D. M.D. F.R.S. M.R.I, (the Author)— IjeGimes on Physiology,

First Series, on Animal Electricity. Svo. 1897.
Zoologiccd Society of London — Proceedings, 1897, Parts 2, 3. Svo.
List of Fellows, 1897. Svo.
Transactions, Vol. XIV. Part 4. 4to. 1897.
Zurich, Naturforschende Gesellschaft — Vierteljahrsschrift, 1897, Heft 2. Svo.

1897.] General Monthly Meeting,

GENEKAL MONTHLY MEETIN

Monday, December 6, 1897. N^ ^ y^

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Hon. Herbert Mills Birdwood, C.S.I. M.A. LL.D.

Major John Leslie, B.A.

Captain Henry George Lyons, R.E. F.G.S.

Cecil Powney, Esq.

were elected Members of the Royal Institution.

The Special Thanks of the Members were returned to Professor
Dewar, LL.D. F.R.S. for his present of a Portrait of Mr. Benjamin
Vincent, Honorary Librarian of the Royal Institution.

The following Lecture arrangements were announced : —

Pkofessoe Oliver Lodge, D.Sc. LL.D. F.R.S. Professor of Physics in
University College, Liverpool. Six Lectures (adapted to a Juvenile Auditory)
on The Principles of the Electric Telegraph. On Dec. 28 {Tuesday^
Dec. 30, 1897; Jan. 1, 4, 6, 8, 1898.

Professor E. PtAY Lankester, M.A. LL.D. F.R.S. Eleven Lectures on
The Simplest Living Things. On Tuesdays, Jan. 18, 25, Feb. 1, 8, 15, 22,
March 1, 8, 15, 22, 29.

Professor Dewar, M.A. LL.D. F.R.S. M.R.I. Fullerian Professor of
Chemistry RJ. Three Lectures on The Halogen Group op Elements. On
Thursdays, Jan. 20, 27, Feb. 3.

Jean Paul Richter, Esq. Ph.D. M.B.I. Three Lectures on Some Italian
Pictures at the National Gallery. On Thursdays, Feb. 10, 17, 24.

Professor J. A. Fleming, M.A. D.Sc. F.R.S. M.B.I. Professor of Electrical
Engineering in University College, London. Five Lectures on Recent
Researches in Magnetism and Diamagnetism. On Thursdays, March 3, 10,
17, 24, 31.

Professor Patrick Geddes, F.R.S.E. Professor of Botany, University
College, Dundee. Three Lectures on Cyprus. On Saturdays, Jan. 22, 29,
Feb. 5.

William Henry Hadow, Esq. M.A. B.Mus. Fellow of Worcester College*
Oxford. Three Lectures on The Structure of Instrumental Music (with
Musical Illustrations). On Saturdays, Feb. 12, 19, 26.

Professor Walter Raleigh, M.A. Three Lectures on English Letter-
Writers. On Saturdays, March 5, 12, 19.

Lionel Gust, Esq. M.A. F.S.A. Director of the National Portrait Gallery.
Two Lectures on Portraip:s as Historical Documents ; Portraits as Monut
ments. On Saturdays, March 26, April 2.

Vol. XV. (No. 91.) 2 m

518 General Monthly Meeting. [Dec. 6,

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FOR

Accademia del Idncei, Eeale, Ttoma — Olasse di Scienze Fisiche, Matematiclie e

Naturali. Atti, Serie Quinta: Kendiconti. 2° Semestre, Vol. VI. Fasc. 8, 9.

Classe di Scienze Morali, &c. Serie Quinta, Vol. VI. Fasc. 7, 8. 8vo. 1897.

American Academy of Arts and Sciences — Proceedings, New Series, Vol. XXII.

Nos. 16, 17 ; .Vol. XXIII. Nos. 1-4. 8vo. 1897.
American Geographical Society — Bulletin, Vol. XXIX. No. 3. Svo. 1897.
American PhiJosojjhical Society — Proceedings, Nos. 153, 155. Svo. 1896-97.
Astronomical Society, /I'o^/aZ— INIonthly Notices, Vol. LVII. No. 9. 8vo. 1897.
Basel, Naturforschende Gesellschaft — Verhandlungen, Band XL. Heft 3. Svo.

1897.
Batavia, Magnetical and Meteorological Observatory— Wind and Weather,
Currents, Tides and Tidal Streams in the East Indian Archipelago. By
J. P. Van der Stok. 4to. 1897.
Belgium, Royal Academy of Sciences, Letters and Fine Arts — Annuaires, 1896-97.
Svo.
Notices Biographiques et Bibliographiques concernant les Membres, etc. 4" ed.

Svo. 1897.
Memoires Couronnes, Tomes XLVIII. (Part 1) XLIX. L. (Part 2) LIII. LIV.

Svo. 1895-96.
Bulletins, Tomes XXX.-XXXIII. Svo. 1895-97.
Keglements. Svo. 1896.

Memoires cour, et des savants e'trang., Tome LIV. 4to, 1896.
Bischoffsheim, B. L. Esq. (the Founder) — Anuales de I'Observatoire de Nice,

Tome VI. 4to. 1897.
Boston Fuhlic Library— Monthly Bulletin, Vol. II. No. 11. Svo. 1897.
Boston Society of Natural History — Proceedings, Vol. XXVIII. Nos. 1-5. Svo.

1897.
British Architects, Boyal Listitute o/— Journal, 3rd Series, Vol. V. Nos. 1, 2.

4to. 1897.
British Astronomical Association — Journal, Vol. VIII, No. 1. Svo. 1897.
Buenos Ayres, Museo Nacional — Memoria p. 1894-96. Svo. 1897.

Annales, Tome V. Svo. 1896-97.
Cambridge Philosophical Society — Transactions, Vol. XVI. Part 2. 4to. 1897.

Proceedings, Vol. IX. Part 6. Svo. 1897.
Camera C/w&— Journal for Nov. 1897. Svo.
Canada, Royal Society — Proceedings and Transactions, 2nd Series, Vol. II.

Svo. 1896.
Cannizzaro, Professor Stanislas (the Author) — Scritti intomo alia Teoria Mole-
colare ed Atomica ed alia Notazione chimica. Pubblicati nel 70 Anniversario
della sua Nascita. (13 July, 1896.) Svo. 1896.
Chemical hidustry. Society o/— Journal, Vol. XVI. No. 10. Svo. 1897.
Chemical Society — Journal for Nov. 1897. Svo.

Proceedings. No. 183. Svo. 1897.
Chicago, John Crerar Library— Annwsil Keports, 1895-96. Svo. 1897.
City of London Co//ege— Calendar, 1897-98. Svo. 1897.
Clinical /Socief?/— Transactions, Vol. XXX. Svo. 1897.
Cracovie, VAcade'mie des Sciences — Bulletin, 1897, No. 8. Svo,
Crawford and Balcarres, The Earl of, K.T. ilf.B.Z— List of MSS. Printed Books
and Examples of Bookbinding exhibited to the American Librarians on the
occasion of their visit to Haigh Hall during the Second International Library
Conference. Svo. 1897.
Editors — American Journal of Science for Nov. 1897. Svo.
Analyst for Nov. 1897. Svo.

Anthony's Photographic Bulletin for Nov. 1897. Svo.
Athenaeum for Nov. 1897. 4to.

1897.] General Monthly Meeting. 519

Editors — continued.

Author for Nov. 1897. 8vo.

Brewers' Journal for Nov. 1897. 8vo.

Chemical News for Nov. 1897. 4to.

Chemist and Druggist for Nov. 1897. 8vo.

Education for Nov. 1897.

Electrical Engineer for Nov. 1897. fol.

Electrical Engineering for Nov. 1897. 8vo.

Electrical Eeview for Nov. 1897. 8vo.

Electricity for Nov. 1897. 8vo.

Engineer for Nov. 1897. fol.

Engineering for Nov. 1897. fol.

Homoeopathic Review for Nov. 1897. 8vo.

Horological Journal for Nov. 1897. 8vo.

Industries and Iron for Nov. 1897. fol.

Invention for Nov. 1897.

Joiu-nal of Physical Chemistry for Nov. 1897.

Journal of State Medicine for Nov. 1897. 8vo.

Law Journal for Nov. 1897. 8vo.

Lightning for Nov. 1897. 8vo.

London Technical Education Gazette for Nov. 1897. 8vo.

Machinery Market for Nov. 1897. 8vo.

Nature for Nov. 1897. 4to.

New Church Magazine for Nov. 1897. 8vo.

Nuovo Cimento for Oct. 1897. 8vo.

Photographic News for Nov. 1897. 8vo.

Physical Review for Oct. 1897. 8vo.

Public Health Engineer for Nov. 1897. 8vo.

Science Siftings for Nov. 1897.

Travel for Nov. 1897. 8vo.

Terrestrial Magnetism for Sept. 1897. 8vo.

Tropical Agriculturist for Nov. 1897.

Zoophilist for Nov. 1897. 4to.
Field Columbian Museum, Chicago— Second Annual Exchange Catalogue, 1897-98.
8vo. 1897.

Observations on a Collection of Papuan Crania. By G. A. Dorsey. 8vo. 1897.
Florence, Bihlioteca Nazionale Centrale — Bolletino, Nos. 284, 285. 8vo, 1897.
Franhlin Institute — Journal for Nov. 1897. 8vo.
Geneva, Societe de Physique et d*Histoire Naturelle —Mcmoires, Tome XXXII.

Part 2. 4to. 1896-97.
Geographical Society, Royal — Geographical Journal for Nov. 1897. 8vo.
Horticultural Society, Boyal—Jonrnal, Vol. XXI. Part 1. 8vo. 1897.
Hiicke, Julius, Esq. (the Author) — Die Geld-Verrichtuugen. 8vo. 1897.
Illinois State Laboratory of Natural History — Bulletin, Vol. IV. 8vo. 1897.
Imperial Institute — Imperial Institute Journal for Nov. 1897.
Johns HopMns University — American Chemical Journal, Vol. XIX. No, 9. 8vo.

1897.
Jordan, W. L. Esq. M.R.I. F.R.G.S. (the Author)— The Ocean: A treatise on
Ocean Currents and Tides and their causes, demonstrating the system of the
World. 2nded. 8vo. 1885.
Linnean Society — Journal, Nos. 168, 229. 8vo. 1897.

Proceedings, Nov. 1896 to June 1897. 8vo. 1897.
Madras Government Museum — Administration Report for 1896-97. fol.
Mechanical Engineers, Institution of — Proceedings, 1896, No. 4^ 8vo. 1897.
Meteorological Society, Royal — Quarterly Journal for Oct. 1897. 8vo.
Navy League — Navy League Journal* for Nov. 1897. 8vo.
Ne^v York Academy of Sciences — Annals, Vol. IX. Nos. 6-12. 8vo. 1897^
Odontological Society — Transactions, Vol. XXX. No. 1. 8vo. 1897.
Paris, Socief(f Fra7icaise de rhysique—HuUctm^ 'No, 10.3. 8vo. 1897.

2 M 2

520 General Monthly Meeting. [Dec. 6,

Pharmaceutical Society of Great Britain — Journal for Nov. 1897. 8vo.
Phillips, Charles E. S. Esq. M.R.I, {the Comj?i7er)— Bibliography of X-Eay Lite-
rature and Research, 1896-97, with Historical Retrospect and Practical

Hints. 8vo. 1897.
Photographic Society, Royal — Photographic Journal for Oct. 1897. 8vo.
Physical Society of London — Proceedings, Vol. XV. Part 11. 8vo. 1897.
Royal Society of London — Philosophical Transactions, Ser. B. Vol. CLXXXIX.

No. 150. 4to. 1897.
Proceedings, No. 380. 8vo. 1897.
Saxon Society of Sciences, Royal —
Mathematisch-Physische Classe —

Abhandlungen, Band XXIV. No. 1. 8vo. 1897.
Selhorne Society — Nature Notes for Nov. 1897. 8vo.
Society of Antiquaries — Proceedings, 2nd Series, Vol. XVI. Nos. 3, 4. 8vo.

1896-97.
Address of Sir A. W. Franks, April 23, 1897. 8vo. 1897.
Society of Arts — Journal for Nov. 1897. 8vo.
Tacchini, Prof. P. Hon. Mem. R.I. (the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXVI. Disp. 9. fol. 1897.
United Service Institution, Royal — Journal for Nov. 1897. 8vo.
United States Department of Agriculture — Experiment Station Record, Vol. IX.

No. 2. 8vo. 1897.
Experiment Station Bulletin, Nos. 43, 44. 8vo. 1897.
North American Fauna, No. 13. 8vo. 1897.
United States Patent O^ice— Official Gazette, Vol. LXXX. Nos. 4-13 ; Vol.

LXXXI. Nos. 1, 2. 8vo. 1897.
Victoria Institute— Journal of the Transactions, No. 115. 8vo. 1897.
Whitworth, The Rev. W. A. M.A. M.R.I.—D C C Exercises, including Hints for

the Solution of all the Questions in ' Choice and Chance.' 8vo. 1897.

1897.]

Contact Electricity of Metals.

521

WEEKLY EVENING MEETING,
Friday, May 21, 1897.

Sm Edward Frankland, K.C.B. D.C.L. LL.D. F.R.S.

Vice-President, in the Chair.

The Right Hon. Lord Kelvin, G.C.V.O. D.C.L. LL.D. F.R.S. M.B.I.

Contact Electricity of Metals.

§ 1. Without preface two 95 years old experiments of Volta's were,
one of them shown, and the other described. The apparatus used
consists of : (a) a Volta-condenser of two varnished brass plates, of
which the lower plate is insulated in connection with the gold leaves
of a gold leaf electroscope, and the upper plate is connected by a
flexible wire with the sole plate of the instrument ; (6) two circular
discs, one of copper and the other of zinc, each polished and unvarnished,
I hold one in my right hand by a
varnished glass stem attached to it,
while on my left hand I hold the
other, which is kept metallically con-
nected with the sole plate of the
electroscope by a thin flexible wire.
To commence the experiment I
place one disc resting on the other,
and lift the two till the upper touches
a brass knob connected by a stiff
metal wire with the lower plate of
the Volta condenser. I break this
contact and then lift the upper plate
of the condenser ; you see no diver-
gence of the gold leaves. This
proves that no disturbing electric
influence sufficient to show any per-
ceptible effect on our gold leaf
electroscope is present. Now I re- i i^.. 1.

peat what I did, with only this

change — I hold the lower disc with the upper disc resting on it two or
three centimetres below the knob. I then with my right hand lift
the upper plate of the Volta-condenser ; you see a very slight diverg-
ence between the shadows of the gold leaves on the screen. I can just
see it by looking direct at the leaves from a distance of about half
a metre. Still holding the lower plate firmly in my left hand in
the same position, and holding the upper plate by the top of its
glass stem in my right, at first resting on the lower plate I lift it and

622 Lord Kelvin [May 21,

let it down very rapidly a hundred times, so as to produce one hun-
dred cycles of operation — break contact between discs, make and
break contact between upper disc and knob, make contact between
discs. Lastly, I lift the upper plate of the condenser ; you see now a
great divergence of the gold leaves, many of you can see it direct on
the leaves, while all of you can see it by their shadows on the screen.
Now, keeping the upper plate of the condenser still unmoved, I bring
a stick of rubbed sealing-wax into the neighbourhood of the electro-
scope ; you see the divergence of the leaves is increased, I remove
the sealing-wax and the divergence diminishes to what it was before.
This proves that the gold leaves diverge in virtue of resinous elec-
tricity upon them, and therefore that the insulated plate of the
condenser received resinous electricity from the copper disc. If now
I interchange the two discs so that the upper is zinc and the lower
copper, and repeat the experiment, you see that the rubbed sealing-
wax diminishes the divergence as it is brought from a distance into
the neighbourhood, and that a glass rod rubbed with silk increases
the divergence. Hence we conclude that in the separation of two
discs of copper and zinc the copper carries away resinous electricity
and the zinc vitreous electricity.

§ 2. Experiment 2. — The same apparatus as in Experiment 1,
except that the polished zinc and copper discs have their opposed
faces varnished with shellac, and are provided with wires soldered to
them for making metallic connection between them when the upper
rests on the lower, as shown in Fig. 2. All operations are the same
as in Experiment 1, but now with this addition — when the upper
disc rests on the lower, make and break metallic contact by hand as
shown in the diagram. The results are the same as those of Experi-
ment 1, except that the quantity of electrification given to the gold
leaves by a single cycle of operations is generally greater than in
Experiment 1, for this reason : In Experiment 1 at the instant of
breaking contact between the zinc and copper there is generally some
degree of inclination between the two discs, while at the corresponding
instant of Experiment 2 they are parallel and only separated by the
insulating coats of varnish. If great care is taken to keep the
discs as nearly as possible parallel at the instant of separation, the
effect of a single separation may be made greater in Experiment 1
than in Experiment 2 (see § 3 below).

§ 3. An instructive variation of Experiment 1 may be made by
giving a large inclination, 5°, or 10°, or 20°, of the upper plate to
the lower, while still in contact and at the instant of separation. By
operating thus the experiment may be made to fail so nearly com-
pletely that no divergence of the leaves will be observed even after
one hundred cycles.

§ 4. These two experiments, with the variation described in § 3,
put it beyond all doubt that Volta's electromotive force of contact
between two dissimilar metals is a true discovery. It seems to have
been made by him about the year 1801 ; at all events he exhibited

1897.]

on Contact Electricity of Metals.

523

his experiments, proving it in that year to a Commission of the
French Institute (Academy of Sciences). It is quite marvellous that
the fundamental experiment (§1 above), simple, easy and sure as it
is,* is not generally shown in courses of lectures on electricity to
students, and has not been even mentioned or referred to in any
English text-book later than 1845, or at all events not in any one

of a large number in which I have looked for it, except in the * Ele-
mentary Treatise on Electricity and Magnetism,' founded on Joubert's
*Traite Elementaire d'Electricite,' by Foster and Atkinson, 1896
(p. 136). The only other places in which I have seen it described
in the English language are Eoget's article in the 'Encyclopaedia
Metropolitana ' referred to above ; Tait's ' Eecent Advances in Physical
Science,' 1876 ; and Professor Oliver Lodge's most valuable, interest-
ing and useful account of all that had been done for knowledge of
contact electricity from its discovery by Yolta till 1884, in his Keport

* Fully and clearly described in Eoget's article on " Galvanism,
• Encyclopaedia Metropolitana,' vol. iv. edition 1845, p. 210.

in the

624

Lord Kelvin

[May 21,

to the Britisli Assocation of that year, ' On the Seat of the Electro-
motive Forces in the Voltaic Cell.'

§ 5. The reason for this unmerited neglect of a great discovery
regarding properties of matter is that it was overshadowed by an
earlier and greater discovery of its author, by which he was led to
the invention of the voltaic pile and crown of cups, or voltaic battery,
or, as it is sometimes called, the galvanic battery. Knowing, as we
now know, both Volta's discoveries, we may describe the earlier
most shortly by saying that the simple experiment (§ 1 above), de-
monstrating the later discovery, is liable to fail if a drop of water
is placed on the lower of the two polished plates. It fails if (see
Fig. 4 below) the last connection between the zinc and copper, when
the upper disc is lifted, is by water. It would not fail (see Fig. 6 below)
nor be sensibly altered from what is found with the dry polished
metals, if the upper disc is slightly tilted in the lifting, so as to
break the water arc before the separation between the metals, and
secure that the last connection is contact of dry metals. To show
this to you more readily than by a Volta condenser with gold leaf
electroscope, I shall now use instead my quadrant electrometer with-
out condenser.

(1) Holding the copper disc connected with the metal case of
the electrometer in one hand, with my other hand I hold by a glass
handle the zinc disc, which you see is connected by a fine wire with
the insulated quadrants of the electrometer. I first place the zinc
resting on the copper, both being polished and dry. You now see
the spot of light at the point marked O on the scale, which I call
the metallic zero. I now lift the zinc disc two or three millimetres
from resting on the copper, and you see the spot of light travelling
largely to the right, which proves that vitreous electricity has passed
from the zinc disc through the connecting wire to the insulated
quadrants of the electrometer. I lower the zinc disc down to rest
again on the copper disc ; you see the spot of light again comes back
to the metallic zero.

(2) I now raise the zinc disc, and with a little piece of wet wood
(or a quill pen) place a little mound of water on the copper disc, as
shown in Fig. 3. I bring down the zinc disc to touch the top of the

Fig. 3.

1897.]

on Contact Electricity of Metals.

525

little mound of water, keeping it parallel to the copper disc so that
there is no metallic contact between them (Fig. 4) ; you see that the

zr

)

u

cc

:>

Fig. 4.

spot of light moves to the left and settles at a point marked E (which
I call the electrolytic zero of our circumstances), a few scale divisions
to the left of the metallic zero. This motion and settlement is the
simplest modern exhibition of Volta's greatest discovery.

(3) Now that the spot of light has settled, I lift the zinc disc
a millimetre till the water column is broken, and then two or three
centimetres farther (Fig. 5); the spot of light does not move, it

remains at E. I lower the zinc disc again : still no motion of the
spot of light, not even when the zinc again touches the little mound
of water.

(4) Now I tilt the zinc disc slightly till it makes a dry metallic
contact with the copper, as shown in Fig. 6 ; while the water arc still

Fig. 6.

626 Lord Kelvin ^ [May 21,

remains unbroken. You see the spot of light, at the instant of
metallic contact, suddenly leaves E and moves to the right, and
settles quickly at the metallic zero after a few vibrations through
diminishing range.

(5) Lastly, I break the metallic contact, and hold the zinc disc
again parallel to the copper (Fig. 4) with the water connection still
remaining unbroken between them ; the spot of light shows no sudden
motion ; it creeps to the left till, in half a minute or three-quarters of
a minute, it reaches its previous steady position on the left. This is
the now well-known phenomenon (never known to Volta) of the re-
covery of a voltaic cell from electrolytic polarisation after a metallic
short-circuit.

§ 6. The succession of experiments described in § 5, interpreted
according to elementary electrostatic law, proves the following con-
clusions : —

(1) When the dry and polished discs of zinc and copper are
metallically connected and held parallel, their opposed faces are
oppositely electrified, the zinc with vitreous electricity, and the copper
with resinous electricity, in quantities varying inversely as the
distance between them when this is small in comparison with the
diameter of each.

(2) The opposed polished faces are non-electrified when polished
portions of the zinc and copper surfaces are connected by water, and
when there is no metallic connection between them. Or, if not
absolutely free from electrification, they may be found slightly elec-
trified, zinc resinously or vitreously, and copper vitreously or resi-
nously, according to difierences in respect to cleanness, polish, or
scratching or burnishing, as exj)lained in § 16 below; and according
to polarisational or other difference in the wetted portions of the
surfaces.

If instead of pure water we take a weak solution of common salt,
or carbonate of soda, or sulphate of zinc or ammonia, we find results
but little affected by the differences of the liquids.

§ 7. But if the polished surface of either the copper or the zinc is
oxidised, or tarnished in any way, notably different results are found
when the experiments of § 5 are repeated with the disc or discs thus
altered.

For example, hold the copper disc, with its polished side up, over
a slab of hot iron, or a spirit lamp, or a Bunsen burner, till you see a
perceptible change of colour, due to oxidation of the previously polished
face. Then allow the copper to cool, and repolish a small area near
one edge ; place a little mound of water upon this area, and operate as
in § 5 (2), (3). The water connection between polished zinc and
polished copper brings the spot of light to the same electrolytic zero
E as before. But now, when we lift the zinc disc and break the water
connection, the spot of light moves to the right, instead of remaining
steady as it does when both the dry opposed surfaces are polished. If

1897.] on Contact Electricity of Metals. 527

next we tarnish the zinc disc by heat, as we did for the copper disc,
and repeat the experiment with wholly polished copper, and with the
zinc disc oxidised where dry, and polished only where wet by the
water connection, we find still the same electrolytic zero E ; but now
the spot of light moves to the left when we lift the zinc disc and
break the water connection.

§ 8. The experiments of § 7, interpreted in connection with those
of § 5, prove that there are dry contact voltaic actions between metallic
copper and oxide of copper in contact with it, and between metallic
zinc and oxide of zinc in contact with it ; according to which, dry
oxide of copper is resinous to copper in contact with it, and dry oxide
of zinc is resinous to zinc in contact with it, just as copper is resinous
to zinc in contact with it. We may verify this conclusion by another
interesting experiment. Taking, for instance, the oxidised copper
plate, with a little area polished for contacts ; put a little mound of
copper, instead of the mound of water, on this area for contact with the
upper plate ; and for the upper plate take polished copper instead of
polished zinc. If we operate now as in § 7, the spot of light settles at
the metallic zero 0 when the metallic contact is made, instead of at
the electrolytic zero E, as it did when we had water connection be-
tween zinc and copper. But now, just as in § 7, the spot of light
moves to the right when the contact is broken and the upper plate
lifted, which proves that vitreous electricity flows into the electro-
meter from the upper plate, when its distance from the lower plate is
increased after breaking the metallic contact. We conclude that when
the two plates were parallel, and very near one another, and when there
was metallic connection between them, vitreous and resinous elec-
tricities were induced upon the opposed surfaces of metallic copper
and oxidised copper respectively. This statement, which we know
from § 7 to be also true for zinc compared with oxidised zinc, is pro-
bably also true for every oxidisable metal compared with any one of its
possible oxides. It is true, as we shall see later (appended paper
of 1880-81 ; also Erskine Murray's paper referred to in § 15), even for
platinum in its ordinary condition in our atmosphere of 21 per cent,
oxygen and 79 per cent, nitrogen, voltaically tested in comparison with
platinum which has been recently kept for several minutes or several
hours in an atmosphere of pure oxygen, or even in an atmosphere of
95 per cent, oxygen and 5 per cent, nitrogen.

§ 9. Hitherto we have had no means of measuring the amount of
the Volta-contact electric force between dry metals, except observa-
tion of the degrees of deflection of the gold leaves of an electroscope,
or of the spot of light of the quadrant electrometer consequent upon
operations performed upon difierent pairs of metals, with dimensions
and distances of motion exactly the same, and comparison of these
deflections with the steady deflection from the metallic zero given by
polished zinc and copper connected conductively with one another by
water, and connected metallically with the two electrodes of an

528 Lord Kelvin [May 21,

electroscope or electrometer. Kohlrausch, in 1851,* devised an appa-
ratus for carrying out this kind of investigation systematically, and
with a good approach to accuracy, by aid of a Dellman's electrometer
and a Daniell's cell, as more definite and constant than a zinc-water-
copper cell. This method of Kohlrausch's for measuring the Volta
electromotive forces between dry metals, " has been employed with
modifications by Hankel, by Gerland, by Clifton, by Ayrton and
Perry, by von Zahn, and by most other experimenters on the subject."t
About thirty-seven years ago, in repetitions of Volta's fundamental
experiment proving contact electricity by electroscopic phenomena
resulting from change of distance between parallel plates of zinc and
copper, I found a null method for measuring electromotive forces
due to metallic contact between dissimilar metals, in terms of the
electromotive force of a Daniell's cell, which is represented diagram-
matically in Fig. 7, and in perspective in Fig. 8. The two discs
are protected against disturbing influences by a metal sheath. The
lower disc is permanently insulated in a fixed position, and is kept
connected with the insulated pair of quadrants of a quadrant electro-
meter. The upper disc is supported by a metal stem passing through
a collar in the top of the sheatb, so that it is kept always parallel to
the lower disc and metallically connected to the sheath, while it can
be lifted a few centimetres at pleasure from an adjustable lowest
position in which its lower face is about half a millimetre or a milli-
metre above the upper face of the lower disc. A portion of the wire
connecting the lower plate to the insulated quadrants of the electro-
meter is of polished platinum, and contact between this and a
platinum-tipped wire connected to the slider of a potential divider
is made and broken at pleasure. For certainty of obtaining good
results it is necessary that these contacts should be between clean
and dry polished metals, because if the last connection on breaking
contact is through semi-moist dust, or oxide, or " dirt " (defined by
Lord Palmerston to be matter in a wrong place), or if it is anything
other than metallic, vitiating disturbance is produced.

§ 10. To make an experiment, first test the insulation with the
upper plate held up in its highest position, and after that with it let
down to its lowest position, in each case proceeding thus : Holding
by hand the wire connected to the slider, run the slider to zero, make
contact at P, observe on the screen the position of the spot of light
from the electrometer mirror for the metallic zero, and then run the
slider slowly to the top of its scale and break contact ; the spot of
light should remain steady, or at all events should not lose more than
a very small percentage of its distance from metallic zero, in half a

* * Poggendorff Annalen,' vols. Ixxv. p. 88 ; Ixxxii. pp. 1 and 45 ; and Ixxxviii.
p. 465, 185] and 1853.

t Prof. O. J. Lodge, * On the Seat of the Electromotive Forces in the Voltaic
Cell,' Brit. Ass. Report, 1884, pp. 464-529.

1897.]

on Contact Electricity of Metali,

529

minute. Eepeat the test with the cell reversed. If the test is
satisfactory with the upper plate high, the insulation of the insulated
quadrants in the electrometer and of the lower disc in the Volta-
condenser is proved good. If after that the test is not satisfactory
with the upper disc at its lowest, we infer that there are vitiating
shreds between the two plates, and we must do what we can to remove
them ; or, if necessary, we must alter the screw-stop at the top so as
to increase the shortest distance between the plates sufficiently to
prevent bridges of shred or dust between them, and so to give good
insulation. The smaller we make the shortest distance with perfect

-100

Fig. 7.

enough insulation, the more sensitive is the apparatus for the
measurement of contact electricity performed as follows.

§ 11. Eun the slider to zero ; make and keep made the contact at P
till the spot of light settles at the metallic zero ; break contact at P,
and lift the upper plate slightly. (If you lift it too far, the spot of
li^ht may fly out of range.) If the spot of light moves in the direction
showing positive electricity on the insulated quadrants (as it does if
the lower plate is zinc and the upper copper), connect the cell to
make the slider negative (as shown in Fig. 7). Eepeat the experi-
ment with the slider at different points on the scale, until you find that,
with contact P broken, lifting the upper plate causes no motion of the
spot of light. If the compensating action with the slider at the top

530

Lord Kelvin

[May 21,

1897.] on Contact Electricity of Metals. 631

of the range is insufficient, add a second cell ; if it is still insufficient,
add a third cell ; if still insufficient, add a fourth.*

§ 12. By this method I made an extended series of experiments in
the years 1859-61, as stated in a short paper communicated to Sec-
tion A of the British Association at its Swansea meeting in August

1880, which with additions published in ' Nature ' for April 14, 1881,
is appended to the present article.

§ 13. Quite independently, "f Mr. H. Pellat found the same method,
and made admirable use of it in a series of experiments described in
theses presented to the Faculty of Sciences in Paris in 1881, J of
which the results, accurate to a degree of minuteness unknown in
previously published researches on the electrical effects of dry contacts
between metals, constitute in many respects the most important and
most interesting extension of our knowledge of contact electricity
since the times of Volta and Pfaff. One of his results (I shall have
to speak of others later) was that Pfaff was right in 1829 § when he
described experiments in which he found no difference in the Volta-
contact-electromotive force between zinc and copper, whether tested in
dry or damp air, oxygen, nitrogen, hydrogen, carburetted hydrogen, or
carbonic acid, so long as no visible chemical action occurred ; and that
De la Eive was not right when he " asserted that there was no Volta
effect in the slightly rarefied air then known as vacuum." || Pfaff ex-
perimented with varnished plates ; Pellat arrived at the same con-
clusion with polished unvarnished plates of zinc and copper. He
found slight variations of the Volta electromotive force due to the
nature of the gas surrounding the plates, and to differences of its
pressure, of which he says : " Ces variations sent tres faibles, par
rapport a la difference de potentiel totale. . . . Ces variations dans
la difference de potentiel sont toujours en retard sur les change-
ments de pression. Elles ne paraissent done pas dependre directement
de celle-ci, mais bien des modifications qui en resultent dans la nature

* The only case hitherto tested by any experimenter, so far as known to me,
in which more than two Daniell cells would be required for the compensation, is
bright metallic sodium, guarded against oxide by glass, in Mr. Erskine Murray's
experiments (§ 18 below), showing volta-difference of 3-56 volts from his standard
gold plate. For direct test this would require four Daniell cells on the potential
divider. The greatest volta-difference of potentials observed by Pellat was 1 • 08
volts, for which a Daniell's cell would rather more than suffice. About 1862 I found
considerably more than the electromotive force of a single Daniell's element
required to compensate the Volta electromotive force between polished zinc and
copper oxidised by heat to a dark purple or slate colour.

t Ann. de Chimie et de Physique, vol. xxiv. 1881, p. 20, footnote.

t ' Theses presente'es a la Faculte des Sciences de Paris, pour obtenir le Grade
de Docteur-es-Sciences Physiques/ par M. H. Pellat, Professeur de Physique au
Lycee Louis le Grand, No. 461, juin 22, 1881. See also 'Journal de Physique,'

1881, xvi. p. 68, and May 1880, ' Diffe'rence de potentiel des couches e'lectriques
qui recouvrent deux metaux en contact.'

§ Ann. de Chim., 2 series, vol. xli. p. 236.
11 Lodge, Brit. Assoc, Report, 1884, pp, 477-8.

632 Lord Kelvin [May 21,

de la surface metallique, modifications qui mettent un certain temps a
Be produire." The smallest pressures for which Pellat made his ex-
periments were from 3 to 4 or 5 cm. of mercury.*

§ 14. The same method was used by Mr. J. T. Bottomley in an
investigation by which he demonstrated with minute accuracy the
equality of the Volta-contact-difference measured in a glass tube
exhausted to less than ^^^3 mm. of mercury* (2^ millionths of
an atmosphere), and immediately after in the same tube filled with
air to ordinary atmospheric pressure; and again exhausted and
filled with hydrogen to atmospheric pressure three times in succes-
sion ; and again exhausted and filled to atmospheric pressure with
oxygen. In some cases the electrical test was repeated several times,
while the gas was entering slowly. The actual apparatus which he
used is before you, and in it I think you will see with interest the
little Volta-condenser, with plates of zinc and copper a little larger
than a shilling, the upper hung on a spiral wire by a long hook
carrying also a small globe of soft iron. Thus you see by aid of an
external magnet I can lift and lower the upper plate without moving
the vacuum tube which, during the experiments, was kept in connec-
tion with a Sprengel pump and phosphoric acid drying tubes. Mr,
Bottomley sums up thus : " The result of my investigation, so far as
it has gone, is that the Volta contact effect, so long as the plates are
clean, is exactly the same in common air, in a high vacuum, in
hydrogen at small and full pressure, and in oxygen. My apparatus,
and the method of working during these experiments, was so sensitive
that I should certainly have detected a variation of 1 per cent, in
the value of the Volta contact efiect, if such a variation had presented

itself." t

§ 15. With the same method further researches have been carried
on by Mr. Erskine Murray, and important and interesting results
obtained, within the last four years, in the Physical Laboratories of
the Universities of Glasgow and Cambridge. He promises a paper
for early communication to the Eoyal Society, and, from a partial
copy of it which he has already given me, I am able to tell you of
some of his results. Taking generally as standard a gilt brass disc
which he found among the apparatus remaining from my experiments
of 1859-61, he measured Volta-differences from it in terms of the
modern standard one volt. These differences are what we may call
the Volta-potentials of the different metallic surfaces, or surfaces of
metallic oxides, iodides, &c., or metallic surfaces altered by cohesion
to them of gases or vapours, or residues of liquids which had been
used for washing them ; if for simplicity we agree to call the Volta-
potential of the gold, zero. As a rule he began each experiment by

* A very high exhaustion had been maintained for two days, and finally per-
fected by two and a half hours' working at the pump immediately before the
electric testing experiment.

t Brit. Assoc. Keport, 1885, pp. 901-3.

1897.1 on Contact Electricity of Metals. 533

polishing the metal plate to be tested on clean glass paper or emery
cloth, and then measured its difference of potential from the standard
gold plate. After that the plate was subjected to some particular
treatment, such as filing or burnishing ; or polishing on leather or
paper ; or washing with water, or alcohol, or turpentine, and leaving
it wet or drying it ; or heating it in air, or exposing it to steam or
oxygen, or fumes of iodine or sulphuretted hydrogen ; or simply
leaving it for some time under the influence of the atmosphere.
The plate as altered by any of these processes was then measured
for potential against the standard gold. Very interesting and in-
structive results were found ; only of one can I speak at present.
Burnishing by rubbing it firmly with a rounded steel tool, or by
rubbing two plates of the same metal together, increased the potential
in every case ; that is to say made the metallic surface more positive
if it was positive to begin with ; or made it less negative or changed it
from negative to positive, if it was negative to begin with. Thus : —

Zinc immediately after being scratched sharply by

polishing on clean glass paper was found . -f *70 volt.

After being burnished with hard steel burnisher it

was found . . . . . . + '94 volt.

After being left to itself for 2 hours it was found + '92 volt.

After further burnishing . . . . + 1*00 volt.

After still further burnishing . . . . -f- 1*02 volt.

It was then scratched by polishing on glass paper,
and its surface potential returned to its original
value of + -70 volt.

§ 16. This seems to me a most important result. It cannot be due
to the removal of oxygen, or oxide, or of any other substance from the
zinc. It demonstrates that change of arrangement of the molecules
at the free surface, such as is produced by crushing them together, as
it were, by the burnisher, affects the electric action between the outer
surface of the zinc and the opposed parallel gold plate. It shows that
the potential * in zinc (uniform throughout the homogeneous interior)

* There has been much of wordy warfare regarding potential in a metal, but
none of the combatants has ever told what he means by the expression. In fai-t
the only definition of electric potential hitherto given has been for vacuum, or
air, or other fluid insulator. Conceivable molecular theories of electricity within
a solid or liquid conductor might admit the term potential at a point in the
interior ; but the function so called would vary excessively in intermolecular space,
and must have a deficite value for every point, whether of intermolecular space or
within the volume of a molecule, or within the volume of an atom, if the atom
occupies space. It would also vary intensely from point to point in the ether or
air outside the metal at distances from the frontier small or moderate in com-
parison with the distance from molecule to molecule in the metal.

But when, setting aside our mental microscopic binocular which shows us atoms
and molecules, we deal with the mathematical theory of equilibrium and motion
of electricity through metals with outer surfaces bounded by ether or air or other

Vol. XV. (No. 91.) 2 n

534 Lord Kelvin [May 21,

increases from the interior tlirougli tlie thin surface layer of a portion
of its surface affected by the crushing of the burnisher, more by
•32 volt than through any thin surface-layer of portions of its surface
left as polished and scratched by glass paper. The difference of
potentials of copper and zinc across an interface of contact between
them is only about 2^ times the difference of potential thus proved to
be produced between the homogeneous interior of the zinc and its free
surface, by the burnishing. Pellat had found that polished metallic
surfaces, seemingly clean and free from visible contamination of any
kind, became more positive by rubbing them forcibly with emery
paper, zinc showing the greatest effect, which was '23 volt. Murray's
burnished surface of zinc actually fell ' 32 volt when scratched by
polishing on glass paper.

§ 17. With two copper plates (a), (h) polished
on emery and each compared with standard

gold, Murray found (a) - -11 volt.

(6) _ -06 volt.
They were then burnished by rubbing them for-
cibly together, and again tested separately ;

he found . ' (a) - -02 volt.

(h) - -02 volt.

Rises of Volta-potential of about the same amount were produced
by burnishing with a steel burnisher copper plates which had been
polished and scratched in various ways. Such experiments as those
of Murray with burnishing ought to be repeated with hammering or
crushing by a Bramah's press. Indeed Pellat * suggested that metals
treated bodily " par le laminage ou le martelage " (rolling or hammer-
ing) might probably show Volta-electric properties of the same kind as,
but more permanent than, those which he had found to be produced
by violent scratching with emery paper.

§ 18. It is interesting to remark that Murray's most highly bur-
nished zinc differed from his emery-polished copper (a) by 1*13

insulating fluids or solids, we find it convenient to use a mathematical function
of position called potential in the interior of each metal. This function must, for
the case of equilibrium, fulfil the condition that it is of uniform value through
each homogeneous portion of metal. Its value must, as a rule, change gradually
(or abruptly) with every gradual (or abrupt) change of quality of substance
occupying space.

To illustrate the difficulty and complexity of expression with which I have
struggled, and to justify if possible my ungainly resulting sentence in the text,
consider the case of a crystal of pure metal : suppose, for example, an octahedron
with truncated corners, all natural faces and facets. In all probability Volta-
differences of potential would be found between the octahedronal and truncational
faces. "We might arbitrarily define the uniform interior potential as the potential
of the air either near an octahedronal face or near a truncational face ; or, still
arbitrarily, we might define it as some convenient mean or average related to
measurements of Volta-difierences of potential between the difierent faces.

* Ann. de Chimie et de Physique, 1881, vol. xxiv. footnote on p. 83.

1897.]

on Contact Electricity of Metals

535

volts. This is considerably greater, I believe, than the highest
hitherto recorded Volta-difference between pure metallic surfaces of
zinc and copper.

By far the greatest Yolta-difference between two metallic sur-
faces hitherto measured is, I believe, 3 • 56 volts, which Murray, in
another part of his work, found as the Volta-diflference between bright
sodium protected by glass and his standard gold. He had previously
found a copper surface after exposure to iodine vapour to be — * 34
relatively to his standard gold. The difference between this iodised
surface and the bright metallic surface of sodium was therefore 3*90
volts : which is the highest dry Volta electromotive force hitherto
known.

§ 19. Seebeck's great discovery of thermoelectricity (1821) was a
very important illustration and extension of the twenty years' earlier
discovery of the contact electricity of dry metals by Volta. It proved
independently of all disturbing conditions that the difference of
potentials between two metals in contact varies with the temperature
of the junction. Thus, for instance, in the copper-iron arrangement

^^

IRON ^

J

25^ 15°

W' ^

i
Copper A

B Copper ^

K

Fig. 9.

represented in Fig. 9, with its hot junction at 25° and its cold at 15°,
the electromotive force tends to produce current from copper to iron
through hot, and its amount is '00148 volt: that is to say, if the
circuit is broken at A B the two opposed faces A, B, at equal tempe-
ratures, present a difference of electric potential of -00148 volt, with
B positive relatively to A. This is not too small a difference to be
tested directly by the Volta-static method, worked by two exactly similar
metal discs connected to A and B, when they are at their shortest
distance from one another, and then disconnected from A and B,
and separated and tested by connection with a delicate quadrant elec-
trometer. But the test would be difficult, because of the difficulty of
preparing the opposed surfaces of two equal and similar discs, so as
to make them equal in their surface- Volta-potentials within one
one-thousandth of a volt, or even to make their difference of potentials
constant during the time of experiment within one one-thousandth of
a volt. There would, however, be no interest in making the experi-
ment in this way, because by the electromagnetic method we can
with ease exhibit and measure with great accuracy the difference of
potentials between A and B, by keeping them exactly at one tempe-

2 N 2

636

Lord Kelvin

[May 21,

rature and connecting them by wires of any kind witli brass or otber
terminals of a galvanometer of higb enough resistance not to sensibly
diminish the difference of potentials between A and B, provided all
the connections between metals of different quality except J and K
are kept at one and the same temperature (or pairrf of them, properly
chosen, kept at equal temperatures).

§ 20. Suppose, now, instead of breaking a circuH of two metals at
a place in one of the metals, as A B in copper in Fig. 9, we break it
at one of the junctions between the two metals, as at C 0, 1' I, Fig. 10.
C D represents a movable slab of copper which (for § 22 below) may
be pushed in so as to be wholly opposite to I' I, or at pleasure drawn
out to any position, still resting on the copper below it as shown in
the diagram. Calling zero the uniform potential over the surfaces
C C D, the potential at I' I would be about + • 16 volt (according to

tRON

Fig. 10.

Murray's results for emery-polished copper and iron surfaces) If the
temperature at J and throughout the system is uniform at about 15° G.
Keeping now the temperature of C C, 1' I exactly at 15°, let the tem-
perature of J be raised to 25°. The difference of potentials between
C'C a-jd I'l would be increased to •16148 volt, supposing '16000 to
have been exactly the difference of potentials when the temperature
of J was 15°. This difference of differences of potentials would be
just perceptible on the most delicate qua;lrant electrometer connected
as indicated in the diagram. Lastly, raise the temperature of C G
and I' I to exactly 25°, J being still kept at this temperature : the
spot of light of the electrometer will return exactly to its metallic
zero. But, would the Volta-difference of potentials between the
surfaces G' G, I' I remain unchanged, or would it return exactly
to its previous value of '16000, or would it come to some other
value ? We cannot answer this question without experiment. The

1897.] on Contact Electricity of Metals. 537

proper method, of course, would he to use the metal-sheathed Volta-
condenser and compensation (§ 9 above), and with it measure the
Volta-dilFerences between copper and ir -n at different tfraperatures,
the same for the two metals in each ctis(\ Tiie slieith and everything
in it should, in each experiment, be kept at one and the same constant
temperature. But it would probably be very diffioult to get a decisive
answer, because of the uncertainties and time-lags of changes in the
Volta-potential of metallic surfaces with change of temperature, which,
if we may judge from Pellat's and Murray's experiments on effects of
temperature when the two metals are unequally heated, would probably
also be found when the temperatures of the two metals, kept exactly
equal, are raised or lowered at the same time.

§ 21. The thermoelectric difference between bismuth and antimony
is about ten times that between copper and iron for temperature diff-
erences of ten or twenty degrees on the two sides of 20° C, and their
Volta-contact difference is exceedingly small (according to Pellat, just
one one-hundredth of a volt when both their surfaces are strongly
scratched by rubbing with emery). It would be very interesting,
and probably instructive, to find how much their Volta-contact differ-
ence varies with temperature by the method at present suggested.
The great variations of Yolta-surface potentials, found by Pellat and
Murray, when one of the two metals is heated, may have been due
to difference of temperatures between the two opposed plates with
air between them ; and it is possible that no such large variation, or
that large variation only due to changes of cohering gases, may bo
found when the two metals are kept at equal temperatures, and these
temperatures are varied as in the experiment I am now suggesting.

§ 22. Peltier's admirable discovery (18^4) of cold produced where
an electric current crosses from bismuth to antimony, and heat where
it crosses from antimony to bismuth, in a circuit of the two metals,
with a current maintained through it by an independent electromotive
force, is highly important in theory, or in attempts for theory, of the
contact electricity of metals.

From an unsatisfactory * hypothetical application of Carnot's
principle to the thermodynamics of thermoelectric currents I long
ago inferred f that probably electricity crossing a contact between
copper and iron in the direction from copper to iron would pro-
duce cold, and in the c(mtrary direction heat when the tempera-
ture is below 280° C. (the thermoelectric neutral temperature of
copper and iron),| and I verified this conclusion by experiment.!

* * Mathematical and Phj^ical Papers,' vol. i. art. xlviii. § 106, reprinted from
* Transactions of the Koyal Society of Edinburgh,' May 1854.

t Ibid. § 116 (19).

J In a thermoelectric circuit of copper and iron the current is from copper to
iron through hot when both junctions are below 280° C. It is from iron to
copper through hot when both junctions are above 280° C.

§ 'Experimental Researches in Tliermoeleetricity,' Proc. R. S. May 1854;
republished as art. li. in * Mathematical and Physical Papers,' vol. i. (seo pp.
464-465).

538 Lord Kelvin [May 21,

Hence we see, looking to Fig. 10, if the movable copper plate C D is
allowed to move inwards (in the position shown in the diagram
it is pulled inwards by the Volta-electrifications of the opposed
surfaces of iron and copper), cold will be produced at the junction J,
all the metal being at one temperature to begin with ; and if we draw
out the copper plate C D, heat will be produced at J. The thermo-
dynamics of this action,* because it does not involve unequal tem-
peratures in different parts of the metals concerned, is a proper subject
for unqualified application of Carnot's law, and has nothing of the
unsatisfactoriness of the thermodynamics of thermoelectric currents,
which essentially involves dissipation of energy by conduction of heat
through metals at different temperatures in different parts. At
present we cannot enter further into thermodynamics than to remark
that when the plate C D is drawn out, the heat produced at J is not
the thermal equivalent of the work done by the drawing out of the
copper plate, but in all probability is very much less than the thermal
equivalent. Probably by far the greater part of the work spent in
drawing out the plate against the electric attraction goes to storing up
electrostatic energy, and but a small part of it is spent on heat
produced at J ; or on excess (positive or negative) of this Peltier
heat above quasi-Peltier (positive or negative) absorptions of heat in
the surface layers of the opposed surfaces when experiencing changes
of electrification.

§ 23. Keturning to Fig. 9 ; suppose, by electrodes connected to
A B and an independent electromotive force, a current is kept flowing
from copper to iron through one junction, and from iron to copper
through the other ; the Peltier heat produced where the current passes
from iron to copper is manifestly not the thermal equivalent of the
work done. In fact, if the two junctions be at equal temperatures
the amounts of Peltier heat produced and absorbed at the two junc-
tions will be equal, and the work done by the independent electro-
motive force will be spent solely in the frictional generation of heat.

§ 24. Many recent writers,! overlooking the obvious principles of
§§ 22, 23, have assumed that the Peltier evolution of heat is the
thermal equivalent of electromotive force at the junction. And in con-
sequence much confusion, in respect to Volta's contact electricity and
its relation to thermoelectric currents, has largely clouded the views

* [March, 1898.] It has been given in a communication to the Eoyal Society
of Edinburgh entitled * The Thermodynamics of Volta-contact Electricity ' ;
Feb. 21, 1898.

t Perhaps following Clerk Maxwell, or perhaps independently. At all events
we find the following in his splendid book of 1873 : " Hence J n represents the
electromotive contact force at the junction acting in the positive direction. . . .
Hence the assumption that the potential of a metal is to be measured by that of
the air in contact with it must be erroneous, and the greater part of Volta's
electromotive force must be sought for, not at the junction of the two metals, but
at one or both of the surfaces which separate the metals from the air or other
medium which forms the third element of the circuit." — ' Treatise on Electricity
and Magnetism,' vol. i. § 249.

1897.] on Contact Electricity of Metals. 539

of teachers and students. We find over and over again the statement
that thermoelectric electromotive force is very much smaller than the
Volta-contact electromotive force of dry metals. The truth is, Yolta-
electromotive force is found between metals all of one temperature, and
is reckoned in volts, or fractions of a volt, without reference to tem-
perature. If it varies with temperature, its variations may be stated
in fractions of a volt per degree. On the other hand, thermoelectric
electromotive force depends essentially on difference of temperature,
and is essentially to be reckoned per degree ; as for example, in fraction
of a volt per degree.

§ 25. Volta's second fundamental discovery, that is, his discovery
(§ 5 above) that vitreous and resinous electricity flow away from zinc
and copper to insulated metals connected with them (for example, the
two electrodes of an insulated electrometer) when the two metals are
separated after having been in metallic contact, makes it quite certain
that there must be electric force in the air or ether in the neighbour-
hood of two opposed surfaces of different metals metallically con-
nected. This conclusion I verified about thirty-six years ago by
experiments described in a letter to Joule, of January 21, 1862,
which he communicated to the Literary and Philosophical Society
of Manchester, published in the Proceedings of the Society and in
' Electrostatics and Magnetism ' (§ 400) under the title of *' A New
Proof of Contact-electricity."

§ 26. Volta's second fundamental discovery also makes it certain
that movable pieces of two metals, metallically connected, attract one
another, except in the particular case when their free surfaces are
Volta-electrically neutral to one another. This force, properly
viewed, is a resultant of chemical af&nity between thin surface layers
of the two metals. And the work done by it, when they are allowed
to approach through any distance towards contact between any parts
of the surfaces, is the dynamical equivalent of the portion of their
heat of combination due to the approach towards complete chemical
combination constituted by the diminution of distance between the
two bodies. To fix the ideas, let the metals be two plane parallel
plates of zinc and copper, with distance between them small in
comparison with their diameters, and let us calculate the amount of
the attractive force between them at any distance. Let V be the
difference of potentials of the air or ether very near the two metallic
frontiers, but at distances from these frontiers amounting at least to
several times the distance from molecule to nearest molecule in either
metal (see footnote on § 16 above). The electric force in air or
ether between these surfaces will be V/D, if D denotes the distance
between them. Hence (our molecular microscopic binocular set
aside) if p is the electric density of either of the opposed surfaces,
A the area of either of the two, and P the attraction between them,
we have

540 Lord Kelvin [May 21,

Hence,

SttD''

Hence the work done by electric attraction in letting them come from
any greater distance asunder D' to any smaller distance D is : —

V2 A / 1 I \ . , , V2 A

if D is very small in comparison with D'.

§ 27. For clean sand-papered copper and zinc * we may take V as
J of a volt c.g.s. electromagnetic, or :j^ c.g.s. electrostatic.

Let now A be 1 sq, cm. and D, 'OOl of a centimetre. We find P
equal to • 249 dyne, and the work done by attraction to this distance
from any much greater distance is -000249. This is sufficient to
heat 5' 9 X 10"^^ grammes of water, 1°.

The table on the next page shows corresponding calculated results
for various distances ranging from 1/100 of a centimetre to 1/10^^ of
a centimetre.

Columns 5 and 6 are introduced to illustrate the relation between
the electric attraction we are considering and chemical affinity as
manifested by heat of combination. The " brass " referred to is an
alloy of equal parts of zinc and copper, assumed to be of specific
gravity 8 and specific heat * 093.

§ 28. It would be exceedingly difficult, if indeed possible at all,
to show by direct experiment, at any distance whatever, the force of
attraction between the discs ; as we see from the table at a distance
of 1/100 of a centimetre it amounts to only 1/400 of a milligramme-
heaviness ; and to only 2 J grammes-heaviness at the distance 10"^ of
a centimetre, which is about ^ of the wave-length of ordinary yellow
light. At the distances 10"^, 10"^, 10'^ of a centimetre the calculated
forces of attraction are 25 kilogrammes, 2J tons,! and 250 tons. This
last force is 2 or 3 times the breaking weight per square centimetre
of the strongest steel (pianoforte wire), 6 times that of copper, 15
times that of zinc. We are, therefore, quite sure that the increase of
attraction according to the inverse square of the distance is not con-
tinued to such small distances as 10'^ of a centimetre; and at dis-
tances less than this, the electric attraction merges into molecular
force between the two metals.

* Pellat's measured values rano^e from "63 to '92, according to the physical
coudition left by less or more violent scrubbing with emery paper. The mean of
these numbers is 17. Murray's range was still wider, from '63 volt to 1'13, the
smallest being for copper burnished, opposed to zinc vscratched and polished with
glass pa[ier; and the Jargest, copper polished merely with emery paper, opposed
to zinc polished and burnished.

t The metrical ton is about 2 per cent, less than ('984 oO the British ton in
general use through the British empire for a good many years before 1890, but
destined, let us hope, to be rarely if ever used after the 19th century, when the
French metrical system becomes generally adopted through the whole world.

1897.]

on Contact BUctricity of Metah.

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642 Lord Kelvin [May 21,

§ 29. Consider, now, a large number of discs of zinc and copper,
each of 1 square centimetre area, and thickness D, and polished on
both sides. On one side of each disc attach three very small columns,
of length D, of glass or other insulating material, and place one disc
on top of the insulators of another, zinc and copper alternately, so as
to make a dry insulated pile of the metal discs, separated by air
spaces each equal to the thickness D. If in the building of this pile
each disc is kept metallically connected with the one over which it is
placed, while it is being brought into its position, work will be done
upon it by electric attraction to the amount shown in column 3, and
the total work of electric attraction during the building of the pile
will be the amount shown in column 3, multiplied by one less than
the number of discs.

But if each disc, after being metallically connected with the one
on which it is to be placed, till it comes within some considerable
distance — say 300 D, for example, from the disc over which it is to
rest — is then disconnected and kept insulated while carried to its
position in the pile, no work will be done on it by electric attraction.
And if now, lastly, metallic connection is made between all the discs
of the pile, currents pass from each copper to each zinc disc, and
heat is generated to an amount equal to that shown in column ,4,
multiplied by one less than the number of discs ; and if this heat
is allowed to become uniformly diffused through the metals, they rise
in temperature to the extent shown in column 6.

All these statements assume that the electric attraction increases
according to the inverse square of the distance between opposed faces
of zinc and copper. We have already (§ 28) seen that this assump-
tion cannot be extended to such small distances as 10"^ of a centi-
metre. We have now further proof of this conclusion beyond the
possibility of doubt, because the large numbers in columns 5 and 6
for 10"^ are enormously greater than any rational estimate we can
conceive for the heat of combination of equal parts of zinc and copper
per gramme of the brass formed. (See § 32 below.)

§ 30. When, on a Friday evening in February 1883 — fourteen
years ago — quoting from an article which had been published in
Nature "j" in 1879, I first brought these views before the Royal Insti-
tution, we had no knowledge of the amount of heat of combination
of zinc and copper, nor indeed of any other two metals. It appeared
probable to us, from Volta's discovery of contact electricity between
dry metals, that there must be some heat of combination ; but I could
then only express keenly-felt discontent with our ignorance of its
amount. Now, however, after twenty-seven years' endurance, I am
happily relieved since yesterday by Professor Roberts Austen, who
most kindly undertook to help me in my preparations for this even-
ing, with an investigation on the heat of combination of copper and
zinc, by which he has found that the melting together of 30 per cent.

* * Nature,' i. 551, " On the Size of Atoms."

1897.]

on Contact Electricity of MetaU.

543

of zinc with 70 per cent, of copper generates about 36 heat-units
(gramme- water-Cent.) per gramme of the brass formed. I am sure
you will all join with me in hearty thanks to him, both for this result
and for his further great kindness in letting us now see a very beau-
tiful experiment, demonstrating a large amount of heat of combination
between aluminium and copper, in illustration of his mode of experi-
menting with zinc and copper, which could not be so conveniently
put before you, because of the dense white fumes inevitable when
zinc is melted in the open air.

[Experiment : A piece of solid aluminium dropped into melted
copper : large rise of temperature proved by thermo-electric test.
Result seen by all in large deflection of spot of light reflected from
mirror of galvanometer.]

§ 31. Another method of investigating the heat of combination of
metals, which I have long had in my mind, is to compare the heat
evolved by the solution of an alloy in an acid with the sum of the
heats of combination of its two constituents in mixed powders. The
former quantity must be less than the latter by exactly the amount
of the heat of combination. This investigation was undertaken a
month ago by Mr. Gait, in the Physical Laboratory of the University
of Glasgow, and he has already obtained promising results ; but many
experimental difficulties, as was to be expected, have presented
themselves, and must be overcome before trustworthy results can be
obtained.

[Added Feb. 1898. — By dissolving a gramme of a powdered alloy,
and again a gramme of mixed powders of the two metals in the
same proportion, in dilute nitric acid, Mr. Gait has now obtained
approximate determinations of heats of combination for four diflferent
alloys, as shown in the following table : —

No.

II.
III.

IV.

Alloy.

("48 per cent, zinc \
\52 „ copper/ **
(Approximately chemical combining
proportions.)*

1 30 per cent, zinc 1
\70 „ copper/

/76*7 per cent, silver \

" \23-3 „ copper/ •'

(Approximately chemical combining

proportions.)*

/51 -6 per cent, silver "I
\48-4: „ copper/

Heat of combination

per gramme of alloy

in gramme-water-

Cent. thermal units.

77

34-6

18

The combining proportions are —

(i) 50 • 8 zinc with 49 • 2 copper,
and (ii) 77-4 silver „ 22*6 „

644 Lord Kelvin [May 21,

The composition stated for the alloy in each case is the result
of chemical analysis. No. I. was intended to be equal parts of zinc
and copper (as being approximately the chemically combining pro-
portions) ; but the alloy, which resulted from melting together equal
parts, was found to have 4 per cent, more copper than zinc, there
having no doubt been considerable loss of the melted zinc by evapo-
ration. No. III. turned out on analysis to be, as intended, very
nearly in the chemically combining proportions of silver and copper.
No. IV. was intended to be equal parts of silver and copper, but
analysis showed the deviation from equality stated in the table. The
proportions of No. II. were chosen for the sake of comparison
with Professor Roberts Austen's result (§ 30), and the agreement
(34: -6 and 36) is much closer than could have been expected, con-
sidering the great difference of the two methods and the great
difficulties in the way of obtaining exact results which each method
presents.

From a chemical point of view it is interesting to see, from
Mr. Gait's results, how much more, both in the case of copper and
zinc, and copper and silver, the heat of combination is, when the
proportions are approximately the chemically combining proportions,
than when they differ from these proportions to the extents found in
Alloys II. and IV. Mr. Gait intends, in continuance of his investi-
gation, to determine as accurately as he can the heats of combination
of many different alloys of zinc and copper and of silver and copper,
and so to find whether or not it is greatest when the proportions are
exactly the chemically " combining proportions." He hopes also to
make similar experiments with bismuth and antimony, using aqua
regia as solvent.]

[§ 32. February 1898. — Looking now to column 5 of the table of
§ 27, we see from Professor Eoberts Austen's result, 36 thermal units,
for the heat of combination of 30 per cent, copper with 70 per cent,
zinc, and from Gait's 77 thermal units for equal parts of copper and
zinc, that the law of electric action on which the calculations of
the tables are founded is utterly disproved for discs of metal of one
one-thousand-millionth of a centimetre thickness, with air or ether
spaces between them of the same thickness, but is not disproved for
thicknesses of one one-hundred millionth of a centimetre.

Consider now our ideal insulated pile (§ 29) of discs 10~^ of a
centimetre thick, with air or ether spaces of the same thickness be-
tween them. Suddenly establish metallic connection between all the
discs. The consequent electric currents will generate 7*4 thermal
units, and heat the discs by 79° C. Take again the insulated column
with thicknesses and distances of 10~^ of a centimetre; remove the
ideal glass separators and diminish the distance to 10~^ of a centi-
metre (the thicknesses of discs being still 10~* of a centimetre). Now,
with these smaller distances between two opposed areas, make metallic
contact throughout the column by bending the corners (the discs for
convenience being now supposed square) ; 74 thermal units will be

1897.] on Contact Electricity of Metals. 645

immediately generated, and the discs will rise 790° in temperature,
and we have a column of hot brass — perhaps solid, perhaps liquid.
This last statement assumes that the law of electric action, on which
the table is founded, holds for discs 10~^ of a centimetre thick, with
ether or air spaces between them of 10~^ of a centimetre. In reality
it is probable that the law of electric action for discs 10~^ of a
centimetre thick, begins to merge into more complicated results of
intermolecular forces, before the distance is as small as 10"* of a
centimetre.

Resuming our mental molecular microscopic binocular (§ 16, foot-
note), we cannot avoid seeing molecular structures beginning to be
perceptible at distances of the hundred-millionth of a centimetre, and
we may consider it as highly probable that the distance from any
point in a molecule of copper or zinc to the nearest corresponding
point of another molecule is less than one one-hundred-millionth,
and greater than one one-thousand-millionth of a centimetre.]

§ 33. In all that precedes I have, by frequent repetition of the
phrase " air or ether," carefully kept in view the truth that the dry
Volta contact-electricity of metals is, in the main, independent of the
character of the insulating medium occupying space around and
between the metals concerned in each experiment, and depends
essentially on the chemical and physical conditions of molecules of
matter in the thin surface stratum between the interior homogeneous
metal and the external space, occupied by ether and dry or moist
atmospheric air or any gas or vapour which does not violently attack
the metal : or by ether with vapours only of mercury and glass and
platinum and steel and vaseline (caulking the glass-stopcocks), as in
Bottomley's experiments (§ 14 above).

This truth has always seemed to me convincingly demonstrated
by Volta's own experiments, and I have never felt that that conviction
needed further foundation ; though of course I have not considered
quite needless or uninstructive, Pfaffs and my own and Pellat's
repetitions and verifications, in different gases at different pressures,
and Bottomley's extension of the demonstration to vacuum of 2J
millionths of an atmosphere. I am now much interested to see by
Professor Oliver Lodge's report, already referred to (§ 4 above), that
in the Bakerian Lecture to the Royal Society in 1806,* Sir Hum-
phry Davy, who had had contemporaneous knowledge of Yolta's
first and second discoveries, expressed himself thus clearly as to the
validity of the second : " Before the experiments of M. Volta on the
electricity excited by mere contact of metals were published, I had
to a certain extent adopted this opinion," an opinion of Fabroni's ;
" but the new fact immediately proved that another power must neces-
sarily be concerned, for it was not possible to refer the electricity
exhibited by the opposition of metallic surfaces to any chemical
alterations, particularly as the effect is more distinct in a dry atmo-

* Phil. Trans. 1807.

646 Lm-d Kelvin [May 21,

sphere, in which even the most oxidisable metals do not change, than
in a moist one, in which many metals undergo oxidation."

§ 34. It is curious to find, thirty or forty years later, De la Rive
explaining away Volta's second discovery by moisture in the atmo-
sphere ! Fifty-one years ago, when I first learned Volta's second dis-
covery, by buying, in Paris, apparatus by which it has ever since been
shown in the ordinary lectures of my class in the University of
Glasgow, I was warned that De la Rive had found it wrong, and had
proved it to be due to oxidation of the zinc by moisture from the air.
I soon tested the value of this warning by the experiments of § 5
above, and a considerable variety of equivalent experiments, in one
of which (real or ideal, I cannot remember which), a varnished zinc
disc, scratched in places and moistened, sometimes on the scratched
parts and sometimes where the varnish was complete, was tested in
the usual manner by separating from contact with an unvarnished or
varnished copper disc, with or without metallic connection when the
discs were at their nearest,

[§§ 35-40 are added in Feb. 1898.]

§ 35. Within the last eighteen or twenty years there has been a
tendency among some writers to fall back upon De la Rive's old hypo-
thesis, of which there are signs in expressions quoted by Professor
Oliver Lodge in his great and valuable report of 1884, and in some
statements also of Professor Lodge's own views.

In what is virtually a continuation of this report in the ' Philo-
sophical Magazine ' a year later,* we find the following with reference
to writings of Helmholtz and myself on the contact-electricity of
metals : " Both these contact theories, in explaining the Volta effect,
ignore the existence of the oxidising medium surrounding the metals.
My view explains the whole effect as the result of this oxygen bath,
and of the chemical strain by it set up." With views seemingly un-
changed, he returned to the subject at the end of 1897 with the
following statement in the printed syllabus of his ' Six Lectures
adapted to a Juvenile Auditory, on the Principles of the Electric
Telegraph ' (Royal Institution, Dec. 28, 1897, Jan. 8, 1898).

" Chemical method of producing a current — Voltaic cell — Two
" differently oxidisable metals immersed in an oxidising liquid and
" connected by a wire can maintain an electric current, through the
" liquid and through the wire, so long as the circuit is closed. [The
" same two metals immersed in a potentially oxidising gas and con-
" nected by a wire, can maintain an electric force or voltaic difference
" of potential in the space between them.]

"N.B. — No one need try too hard to understand sentences in
brackets,"

And lastly, after some correspondence which passed between us

t Prof. O. Lodge ' On the Seat of the Electromotive Force in a Voltaic Cell,*
Phil. Mag. Oct. 1885, p. 383.

1897.] on Contact Electricity of Metals. 547

in December, I have to-day (Feb. 14), received from him a "slightly
amplified statement made in order to concentrate the differences,"
which he kindly gives me for publication as a supplement to the
shorter statement from the syllabus.

Amplification, February, 1898.

" There is a true contact-force at a zinc-copper junction,* which
" on a simple and natural hypothesis (equivalent to taking an inte-
" gration-constant as zero) can be measured thermoelectrically f and
" is about ^ millivolt at 10° C.

" A voltaic force, more than a thousand times larger,f exists at
" the junction of the metals with the medium surrounding them ; and
" in an ordinary case is calculable as the difference of oxidation-
" energies of zinc and copper ; but it has nothing to do with the heat
" of formation of brass.

" References :

" Phil, Mag. [5].

" vol. xix. pp. 360 and 363, brass and atoms, pp. 487 and 494, summary.

" vol. xxi. pp. 270 and 275, thermoelectric argument.

'• vol. xxii. p. 71, Ostwald experiment.

" August 1878, Brown experiment."

§ 36. With respect to the first of the two paragraphs of this
last statement and the first two lines of the second, the wrongness
of the view there set forth is pointed out in § 24 above. With
respect to the last clause of the second paragraph and the statement
quoted from the syllabus, I would ask any reader to answer these
questions : —

(i.) What would be the ef&cacy of the supposed oxygen bath in
the experiments of § 2 above with varnished plates of zinc and
copper ? or in Erskine Murray's experiment, described in his paper
communicated last August to the Eoyal Society, in which metallic
surfaces, scraped under melted paraffin so as to remove condensed
oxygen or nitrogen from them, and leave fresh metallic surfaces in
contact with a hydro-carbon, are subjected to the Voltaic experiment ?
or in Pfaff's and my own and Pellat's experiments with different
gases, at ordinary and at low pressures, substituted for air ? or in
Bottomley's high vacuum and hydrogen and oxygen experiments
(§ 14 above) ?

(ii.) What would be the result of Volta's primary experiment,
shown at the commencement of my lecture (§1 above), if it had been
performed in some locality of the universe a thousand kilometres
away from any place where there is oxygen ? The insulators may
be supposed to be made of rock-salt or solid paraffin, so that there
may be no oxygen in any part of the apparatus. This I say because
I understand that some anti-Voltaists have explained Bottomley's

* See footnote on § 16 above. K. Feb. 14, 1898.
t See § 24 above. K. Feb. 14, 1898.

548 Lord Kelvin [May 21,

experiments by the presence of vapour of silica from the glass, sup-
plying the supposedly needful oxygen !

§ 37. The anti-Voltaists seem to have a super«3titious veneration
for oxygen. Oxygen is entitled to respect because it constitutes
60 per cent, of all the chemical elements in the earth's crust ; but
this gives it no title for credit as coefficient with zinc and copper in
the dry Volta experiment, when there is none of it there. Oxygen
has more affinity for zinc than for copper ; so has chlorine and so has
iodine. It is partially true that different metals — gold, silver, plati-
num, copper, iron, nickel, bismuth, antimony, tin, lead, zinc,
aluminium, sodium — are for dry Volta contact electricity in the order
of their affinities for oxygen ; but it is probably quite as nearly true
that they are in the order of their affinities for sulphur, or for oxy-
sulphion (SO4) or for phosphorus or for chlorine or for bromine. It
may or may not be true that metals can be unambiguously arranged
in order of their affinities for any of these named substances ; it is
certainly true that they cannot be definitely and surely arranged in
respect to their dry Volta contact-electricity. Murray's burnishing,
performed on a metal which has been treated with Pellat's washing
with alcohol and subsequent scratching and polishing with emery,
alters the Volta quality of its surface far more than enough to change
it from below to above several metals polished only by emery ; and,
in fact, Pellat had discovered large differences due to molecular con-
dition without chemical difference, before Murray extended this funda-
mental discovery by finding the effect of burnishing.

§ 38. Eeturning to Professor Lodge's supposed oxygen bath (§ 35) ;
if it exists between the zinc and copper plates, it diminishes or
annuls or reverses the phenomenon, to explain which he invokes its
presence (see § 5 above).

§ 39. Many years ago I found that ice, or hot glass, pressed on
opposite sides by polished zinc and copper, produced deviations from
the metallic zero of the quadrants of an electrometer metallically
connected with them in the same direction as if there had been water
in place of the ice or hot glass. From this I inferred that ice and
hot glass, both of which had been previously known to have notable
electric conductivity, acted as electrolytic conductors.

Experiments made by Maclean and Goto in the Physical Labo-
ratory of the University of Glasgow in 1890,* proved that polished
zinc and polished copper, with fumes passing up between them from
the flame of a spirit-lamp 30 centimetres below, gave, when metallic-
ally connected to the quadrants of an electrometer, deviations from
the metallic zero in the same direction, and of nearly the same amount,
as if cold water had been in place of the flame. This proved that
flame acted as an electrolytic conductor. They also found that hot air
from a large red-hot soldering bolt, put in the place of the spirit lamp,
had no such effect ; nor had breathing upon the plates, nor the vapour

* Phil. Mag. Aug. 1890.

1897.] on Contact Electricity of Metals. 549

of hot water, any effect of the kind. In fact hot air, and either cloudy
or clear steam, act as very excellent insulators ; but there is some
wonderful agency in fumes from a flame, remaining even in cooled
fumes, in virtue of which the electric effect on zinc and copper is
nearly the same as if continuous water, instead of fumes, were between
the plates and in contact with both.*

A similar conclusion in respect to air traversed by ultra-violet
light was proved by Righi, f Hallwachs, J Elster and Geitel, § Branly. ||
The same was proved for ordinary atmospheric air, with Eontgen
rays traversing it between plates of zinc and copper, by Mr. Erskine
Murray, in an experiment suggested by Professor J. J. Thomson, and
carried out in the Cavendish Laboratory of the University of Cam-
bridge. H

§ 40. The substitution for ordinary air between zinc and copper, of
ice or hot glass, or of air or gas modified by flame or by ultra-violet
rays, or by Eontgen rays, or by uranium (§§ 41, 42 below), gives us,
no doubt, what would to some degree fulfil Professor Lodge's idea of a
" potentially-oxidising " gas, and each one of the six fails wholly or
partially to " maintain electric force or voltaic difference of potential
in the space between them." In fact, Professor Lodge's bracketed
sentence, so far as it can be understood, would be nearer the truth if
in it " cannot " were substituted for " can." I hope no reader will
consider this sentence too short or sharp. I am quite sure that Pro-
fessor Lodge will approve of its tone, because in his letter to me of
the 14th, he says, " In case of divergence of view it is best to have
both aspects stated as crisply and distinctly as possible, so as to
emphasise the difference." I wish I could also feel sure that he will
agree with it, but I am afraid I cannot, because in the same letter he
says, " I am still unrepentant."

Continuation of Lecture of May 21, 1897,

§ 41. In conclusion, I bring before you one of the most won-
derful discoveries of the century now approaching its conclusion,
made by the third of three great men, Antoine Becquerel, Edmond
Becquerel, Henri Becquerel — father, son and grandson — who by their
inventive genius and persevering labour have worthily contributed to
the total of the scientific work of their time ; a total which has
rendered the nineteenth century more memorable than any one of all
the twenty-three centuries of scientific history which preceded it,
excepting the seventeenth century of the Christian era.

You see this little box which I hold in my right hand, just as I
received it three months ago from my friend Professor Moissan, who
will be here this day week to show you his isolation of fluorine. It

♦ Kelvin and Maclean, R.S.E. 1897. t Rend. R. Ace. dei Lincei, 1888, 1889.

t Wiedemann's Annalen, 34, 1888. § Ibid. 38, 41, 1888.

U Comptes Eendus, 1888, 1890. i Proc. R.S. March 1896.
Vol. XV. (No. 91.) 2 o

550 Lord KeMn [May 21,

induces electric conductivity in the air all round it. If I were to
show you an experiment proving this, you might say it is witchcraft.
But here is the witch. You see, when I open the box, a piece of
uranium of about the size of a watch. This production of electric
conductance in air is only one of many marvels of the " uranium
rays" discovered a year ago by Henri Becquerel, of no other of
which can I now speak to you, except that the wood and paper of
this box, and my hand, are to some degree transparent for them.

I now take the uranium out of its box and lay it on this hori-
zontal copper plate, fixed to the insulated electrode of the electrometer.
I fix a zinc plate, supported by a metal stem which is in metallic
connection with the sheath of the electrometer, horizontally over the
copper plate at a distance of about one centimetre from the top of the
Uranium. Look at the spot of light ; it has already settled to very
nearly the position which you remember it took when we had a
water-arc between the copper and zinc plptes, connected as now,
copper to insulated quadrants and zinc t,o tl^e sheath. I now lift
the uranium, insulating it from the copper plate by three very small
pieces of solid paraffin, so as to touch neither plate, or, again, to
touch the zinc but not the copper. This change makes but little
difference to the spot of light. I tilt the uranium now to touch the
zinc above and the copper below; the spot of light comes to the
metallic zero as nearly as you can see. I leave it to itself now,
resting on its paraffin supports and not touching the zinc, and the
spot of light goes back to where it was ; showing about three-quarters
of a volt positive.

§ 42. I now take this copper wire, which is metallically connected
with the zinc plate and the sheath of the electrometer, and bring it to
touch the under side of the copper shelf on which the uranium is sup-
ported by its paraffin insulators. Instantly the spot of light moves
towards the metallic zero, and after a few vibrations settles there. I
break the contact ; instantly the spot of light begins to return to its
previous position, where it settles again in less than half a minute.
You see, therefore, that if I re-make and keep made the metallic
contact between the zinc and copper plates, a current is continuously
maintained through the connecting wire, by which heat is generated
and radiated away, or carried away by the air ; as long as the con-
tact is kept made. What is the source of the energy thus produced ?
If we take away the uranium, and send cool fumes from a spirit-
lamp, or shed Rontgen rays or ultra-violet light, between the zinc
and copper, the results of breaking and making contact would be just
what you see with uranium. So would they be — you have already,
in fact, seen them (§ 5) — without either Eontgen rays or ultra-violet
light, but with the copper and zinc a little closer together and with
a drop of water between them : and so would they be with dry ice,
or with hot glass, between and touched by the zinc and copper. In
each of these six cases we have a source of energy ; the well-known
eluctro-chemical energy given by the oxidation of zinc in the last

1897.] on Contact Electricity of Metals. 661

mentioned three cases ; and the energy drawn upon by the cooled
fumes, or by the Eontgen rays or ultra-violet light, acting in some
hitherto unexplained manner, in the three other cases. We may
conjecture evaporations of metals; we have but little confidence in
the probability of the idea. Or does it depend on metallic carbides
mixed among the metallic uranium? I venture on no hypothesis.
Mr. Becquerel has given irrefragable proof of the truth of his dis-
covery of radiation from uranium of something which we must admit
to be of the same species as light, and which may be compared with
phosphorescence. When the energy drawn upon by this light is
known, then, no doubt, the quasi electrolytic phenomena, induced by
uranium in air,* which you have seen, will be explained by the same
dynamical and chemical principles as those of the previously known
electrolytic action of cooled fumes from a spirit-lamp, and of air
traversed by Rontgen rays or ultra-violet light.

Appendix.

On a Method of Measuring Contact Electricity. \

In my reprint of papers on Electrostatics and Magnetism (§ 400, of
original date, January 1862) I described briefly this method, in con-
nection with a new physical principle, for exhibiting contact elec-
tricity by means of copper and ziiic quadrants substituted for the
uniform brass quadrants of my quadrant electrometer. In an extensive
series of experiments which I made in the years 1859-61, I had used
the same method, but with movable discs for the contact electricity,
after the method of Volta, and my own quadrant electrometer substi-
tuted for the gold-leaf electroscope by which Volta himself obtained
bis electric indications.

I was on the point of transmitting to the Eoyal Society a paper
which I had written describing these experiments, and which I still
have in manuscript, when I found a paper by Hankel in Poggendorf 's
* Annalen ' for January, 1862, in which results altogether in accord^
ance with my own were given, and I withheld my paper till I might
be able not merely to describe a new method, but if possible, add
something to the available information regarding the properties of

* Experiments made in the Physical Laboratory of the University of Glasgow
[§33 of Kelvin, Beattie and Smolan, Proc. E.S.E. ; also 'Nature,' March°ll,
1897, and Phil. Mag. March 1898] show this electrolytic conductivity to be
produced by uranium to nearly the same amount in common air oxygen and
carbonic acid ; and to about one-third of the same amount in hydrogen, at
ordinary atmospheric pressure ; but only to about yi^ of this amount in each of
these four gases at pressures of 2 or 3 millimetres. There seems every reason
to believe that it would be non-existent in high vacuum, such as that reached by
Bottomley in his Volta-contact experiments (§14 above).

t First published in the British Association, Swansea meeting, August 1880,
ond ' Nature,' April 4. 1881.

2 o 2

552 Lord Kelvin [May 21,

matter to be found in Hankel's paper. I have made many experi-
ments from time to time since 1861 by the same method, but have
obtained results merely confirmatory of what had been published by
Pfatf in 1820 or 1821, showing the phenomena of contact electricity
to be independent of the surrounding gas, and agreeing in the main
with the numerical values of the contact differences of different metals
which Hankel had published ; and I have therefore hitherto published
nothing except the slight statements regarding contact electricity
which appear in my ' Electrostatics and Maguetism.' As interest has
been recently revived in the subject of contact electricity, the follow-
ing description of my method may possibly prove useful to experi-
menters. The same method has been used to very good effect, but
with a Bohnenberger electroscope instead of my quadrant electrometer,
in researches on contact electricity by Mr. H. Pellat, described in the
* Journal de Physique ' for May 1880.

The apparatus used in these experiments was designed to secure
the following conditions : To support, within a metallic sheath, two
circular discs of metal about four inches in diameter in such a way
that the opposing surfaces should be exactly parallel to each other
and approximately horizontal, and that the distance between them
might be varied at pleasure from a shortest distance of about one-
fiftieth of an inch to about a quarter or half an inch. This part of
the apparatus I have called a " Yolta-condenser." The lower plate,
which was the insulated one, was fixed on a glass stem rising from
the centre of a cast-iron sole plate. The upper plate was suspended
by a chain to the lower end of a brass rod sliding through a steady-
ing socket in the upper part of the sheath. An adjustable screw on
this stem prevents the upper plate from being let down to nearer than
about one-fiftieth of an inch, or whatever shortest distance may be
wanted in any particular case. A stout brass flange fixed to the
lower end of this rod bears three screws, one of which S is shown in
the drawing, by which the upper plate can be adjusted to parallelism
to the lower plate. The other apparatus used consisted of a quadrant
electrometer, and in my original experiments an ordinary Daniell's
cell, in my later ones a gravity Daniell's cell of the form which I
described in ' Proc. E.S.' 1871 (pp. 253-259), with a divider by which
any integral number of per cents, from 0 to 100 of the electromotive
force of the cell could be established between any two mutually insu-
lated homogeneous metals in the apparatus.

Connections. — The insulated plate was connected by a brass wire
passing through the case of the Volta-condenser to the electrode of
the insulated pair of quadrants. The upper plate was connected to
the metal sheath of the Volta-condenser, and to the metal case of the
electrometer, one pair of quadrants of which were also connected to
the case. One of the two terminals of the divider, connected to the
poles of the cell, was connected to the case of the electrometer. To
the third terminal (the bar carrying the slider) was attached one of
the contact wires, which was a length of copper wire having soldered

1897.] on Contact Electricity of Metals. 553

to its outer end a short piece of platinum. The other contact surface
was a similar short piece of platinum fixed to the insulated electrode
of the electrometer. Hence it will be seen that metallic connection
between the two plates was effected by putting the divider at zero and
bringing into contact the two pieces of platinum wire.

Order of Experiment. — The sliding piece of the divider was put
to zero, and contact made and broken, and the upper plate raised :
then the deflection of the spot of light was observed. These opera-
tions were repeated with the sliding piece at ditFerent numbers on
the divider scale, until one was found at which the make-break and
separation caused no perceptible deflection. The number thus found
on the divider scale was the percentage of the electromotive force of
the Daniell cell, which was equal to the contact electric difference
of the plates in the Volt-condenser.

[Addendum, November 23, 1880. — Since the communication of
this paper to the British Association, I have found that a dry plati-
num disc, kept for some time in dry hydrogen gas, and then put into
its position in dry atmospheric air in the apparatus for contact elec-
tricity, becomes positive to another platinum disc which had not
been so treated, but had simply been left undisturbed in the apparatus.
The positive quality thus produced by the hydrogen diminishes
gradually, and becomes insensible after two or three days.]

P.S. — On December 24, 1880, one of two platinum plates in the
Volta-condenser was taken out ; placed in dried oxygen gas for forty-
five minutes ; taken out, carried by hand, and replaced in the Volta-
condenser at 12.30 on that day. It was then found to be negative
to the platinum plate, which had been left undisturbed. The amount
of the difference was about • 33 of a volt. The plates were left un-
disturbed for seventeen minutes in the condenser, and were then
tested again, and the difference was found to have fallen to -29 of a
volt. At noon on the 25th they were again tested, and the diflerence
found to be * 18. The differences had been tested from time to time
since that day, the plates having been left in the condenser undis-
turbed in the intervals. The following table shows the whole series
of these results : —

Electric difference between
surfaces of a platinum plate in
Time. natural condition, and a platinum

plate after 45 minutes' expoeore
to dry oxygen gas.

Dec. 24, 12.30 p.m '33 of a volt.

24, 12.47 p.m -29 „

25, noon '18 „

27, noon '116 „

28, 11.20 a.m -097 „

31, noon -047 „

Jan. 4, 11.0 a.m -042 „

11, 11.40 a.m -020 „

Mr. Rennie, by whom these experiments were made during the
recent Christmas holidays, had previously experimented on a platinum

554 Lord Kelvin on Contact Electricity of MetaU. [May 21,

plate which had been made the positive pole in an electrolytic cell
with an electromotive force of one volt, tending to decompose water
acidulated with sulphuric acid ; the other pole being a piece of plati-
num wire. After the plate had been one hour under this influence
in the electrolytic cell he removed it, and dried it by lightly rubbing
it with a piece of linen cloth. He then placed it in the Volta-
condenser, and found it to be negative to a platinum plate in
ordinary condition ; the difference observed was * 27 of a volt. This
experiment was made on October 21 ; and on November 8 it was
found that the difference had fallen from '27 to '07, Mr. Eennie
also made similar experiments with the platinum disc made the
negative pole in an electrolytic cell, and found that this rendered
the platinum positive to undisturbed platinum to a degree equal
to about • 04 of a volt. The effect of soaking the platinum plate in
dry hydrogen gas, alluded to in my first postscript, which also was
observed by Mr. Eennie, was found to be about 'll of a volt. Thus
in the case of polarisation by hydrogen, as well as in the case of
polarisation by oxygen, the effect of exposure to the dry gas wa&
considerably greater than the effect of electro-plating the platinum
with the gas by the electromotive force of one volt.

[K.1

18 97.] Projperiies of Liquid Oxygen, 665

WEEKLY EVENING MEETING,

Friday, January 22, 1897.

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.E.S.

Honorary Secretary and Vice-President,
in tlie Chair.

Professor Dewar, M.A. LL.D. F.R.S. M.B.I.

Fullerian Professor of Chemistry E.I.

Properties of Liquid Oxygen.

Gaseous Absorption. — During recent years a great deal of research
has been directed to the study of what may be called the low tempera-
ture absorption spectrum of gaseous and liquid oxygen. It has been
shown that gaseous oxygen gives two types of absorption spectrum, one
composed of a number of well-defined groups of lines of exquisite sym-
metry, like the great groups A and B of the solar spectrum, the other
of bands relatively broad and more or less black. The band spectrum is
especially marked in gaseous oxygen under high pressure, and Janssen
has shown that the intensity of absorption in different columns of
gas under different pressure is identical when the length multiplied
into the square of the density is the same in each case. The band
that is most easily seen is one in the yellow, and, in order just to see
it, 18 metres of oxygen under 11 atmospheres pressure (or 11 times
the density under ordinary pressure) must be traversed by white light
before it enters the spectroscope. From this result and Janssen's law
just given, it follows that in order to detect the same band in a
column of gaseous oxygen at atmospheric pressure, it would require to
be 2178 metres long or about 1^ miles. The question arises what
would be the length of an oxygen tube at atmospheric pressure, equi-
valent to the absorption of a beam passing vertically through the
earth's atmosphere. This problem has been answered by Janssen,
who has shown that an oxygen column 172 metres long would have a
similar action. It follows at once from this result that the band in
the yellow cannot be seen in the spectrum of the midday sun, as
it would require a column of oxygen at least twelve times longer in
order to make it visible ; but that it ought to be seen provided the
sun was observed near the horizon. When the sun is 4° above the
horizon, the depth of atmosphere the rays have to penetrate is about
twelve times that of the zenithal thickness. This theoretical result
Janssen has confirmed by a series of observations made at sunrise
in the dry air of the Desert of Sahara.

Liquid Absorption. — Both types of spectra are well marked in the
spectrum of liquid oxygen, the only marked difference being that the

556

Professor Bewar

[Jan. 22,

liquid absorption known as A and B of Frauenhoffer appear now as
bands with sharp edges on the less refrangible side, fading away
gradually towards the more refrangible, which is just the opposite
character to that of the gaseous absorption of the same groups. The
change from the gaseous to the liquid state has not caused any material
alteration in the general character of the absorption from what it
was under high gaseous compression. The question may therefore
naturally be put, does Janssen's law expressing the relation of absorp-
tion and density in the gaseous state extend to the liquid condition ?
This may be answered by calculating what thickness of the liquid at
its boiling point, taken as being 800 times denser than the gas at
ordinary temperatures, would be required (provided the same law held)
to render visible the absorption band in the yellow. The resulting
number is about 3 * 4 mm., and this is confirmed by laboratory experi-
ments which show that between 3 and 4 mm. thickness of liquid oxygen
at ■- 183° is sufficient to cause the appearance of this band. Thus it
appears Janssen's law extends to the liquid condition, the square of
the density still defining the intensity of the absorption. It is pro-
bable that the band spectrum has its origin either in complex mole-
cules generated by condensation, or it may originate from encounters
between molecules of the ordinary mass which become more frequent
when the free path is diminished. The following table gives the
results of observations (made with my colleague Prof. Liveing) in
order to find the gaseous pressure required to originate definite
absorption bands together with some data of liquid absorption.

Wave-Length
of Band.

Atmospheric

Pressure.
18-metre tube.

Atmospheric

Pressure.

!• 65-metre tube.

Atmospheric

Pressure.

2178 metres tube.

Thickness of
Liquid.

A

5785
(yellow band)

6300\
4700/

5350\
4470/

1
12
11

20
30

20
40
35

110

1

30 mm.
3 to 4 mm.

The gaseous oxygen in the 1 • 65-metre tube under 85 atmospheres
compression appears to be very transparent for violet and ultra-violet
up to the wave-length 2745, or about the limit of the magnesium
spark spectrum. When the pressure was increased to 140 atmo-
spheres the ultra-violet absorption was complete beyond wave-length
2704. In the 18-metre tube with the oxygen under 90 atmospheres
pressure, a faint absorption band appeared about L of the solar
spectrum, a strong one between 3640 and 3600 wave-length, and a

1897.] on Properties of Liquid Oxygen. 557

diffuse band about the solar line O with complete absorption beyond
P. The intensity of the absorption in the latter case was, following
Janssen, 4J times what it was under the highest pressure in the
short tube. From this we should infer that in the liquid state
medium thicknesses like a centimetre or two would be transparent to
the ultra-violet, but depths of 10 to 20 cm. would become more
and more opaque. Actual experiments confirm this suggestion.

Thus the passage of light through a layer of liquid 3 to 4 mm.
thick is sufficient to cause visible absorption in the yellow, while it
requires more than five hundred thousand times this thickness of
oxygen gas at atmospheric pressure to do the same thing. Provided
the density of tbe oxygen gas is much below that corresponding to
the atmosphere, then an enormous thickness of gaseous oxygen would
be required to cause any visible absorption. This may explain why
such a spectrum is not shown in sunlight, quite independently of the
earth's atmosphere, provided we assume that any oxygen in the solar
atmosphere must have a relatively small density.

Absorption of Liquid Air. — If the surface of the earth was cooled
to below — 200° C. then the atmosphere would liquefy, and the ocean
of liquid air would form a depth of about 80 to 35 feet. The actual
proportionate depth can be experimentally observed by taking a tube
about 52 feet long, or about 3^^th part of the height of the homo-
geneous atmosphere, and cooling one end to — 210°, when about
f inch of liquid is obtained. Of this liquid air layer, about 6 to
7 feet may be taken as the equivalent of the oxygen portion. A
question of considerable interest arises as to the effect of the presence
of liquid nitrogen on the oxygen absorption ; although nitrogen is
colourless yet the dilution of the liquid oxygen in a neutral solvent
has altered the concentration of the colour-absorbing medium. In
order to examine into this matter Professor Liveing and the author
compared the absorption of 1*9 cm. of liquid air with 0*4 cm. of
liquid oxygen, or the proportionate thickness of oxygen which the
layer of 1 * 9 cm. of liquid air contains. The light which had passed
through the latter was, by means of a reflecting prism, brought into
the field of view of the spectroscope at the same time with that
which had passed through the liquid air. The positions of the lamps
were then adjusted so that the brightness of the spectra of those
parts where there were no absorption bands was equal in the two
spectra. Under these circumstances it was seen that the absorption
bands were very much more strongly developed by 0 ' 4 cm. of liquid
oxygen than by five times that thickness of liquid air.

Another sample of liquid air was rapidly mixed with an equal
volume of liquid oxygen, and the absorption of this liquid compared
as before with that of liquid oxygen. It was seen that the absorption
of 2 • 4 cm. of the mixture was much greater than that of 0 • 4 cm. of
liquid oxygen. The density of the liquid oxygen in the mixture
was, in fact, three times that in pure liquid air, and by an extension
of Janssen's law to liquid mixtures the absorption should have been

558 Professor Dewar [Jan. 22,

increased ninefold. The observations, so far as they go, accord with
this theory. In order to examine the effect of temperature, the ab-
sorption of a thickness of 3 cm. of liquid oxygen boiling under 1 cm.
pressure, or at a temperature of —210°, was compared with a like
thickness of the liquid boiling at atmospheric pressure. With the
colder liquid the bands in the orange and yellow were sensibly
widened, mainly on the more refrangible side ; the faint band in the
green was plainly darker, and the band in the blue appeared some-
what stronger. The difference between the temperatures of the two
liquids was about 27°, or approaching to one-third the absolute
boiling-point of oxygen. The density of oxygen at — 210° C. is not
known, but in any case it is greater than that at — 183° C, and an
increased absorption of about one-fourth by the cooling might be
anticipated.

At the low temperature reached by the use of a hydrogen jet taken
in liquid air, the latter solidifies into a hard white solid resembling
avalanche snow. The solid has a pale bluish colour, showing by
reflection all the absorption bands of the liquid.

The refractive power of the liquid, as determined by Prof. Liveing
and the author, was given in a previous lecture.* Later investigations
resulted in the determination of the dispersive power. The refractive
constant of the liquid oxygen was found to be almost identical with
Mascart's value for the gas, and similarly the dispersive constant in
the liquid and gas seems to be identical.

Magnetic Properties of Liquid Oxygen.

The remarkable magnetic properties of liquid oxygen were de-
scribed to the Royal Institution in a lecture delivered in 1892.t
Professor Fleming and myself have for some time past directed our
attention to the question of determining the numerical values of the
magnetic permeability and magnetic susceptibility of liquid oxygen,J
with the object of determining not only the magnitude of these
physical constants, but also whether they vary with the magnetic
force under which they are determined.

Although a large number of determinations have been made by
many observers of the magnetic susceptibility of different liquids
taken at various temperatures, difficulties of a particular kind occur
in dealing with liquid oxygen. One method adopted for determining
the magnetic susceptibility of a liquid is to observe the increase of
mutual induction of two conducting circuits suitably placed, first in
air, and then when the air is replaced by the liquid in question, the

♦ "Liquid Atmospheric Air," Proc. Eoy. Inst. 1893.

t See Roy. Inst. Proc. June 15th, 1892, "On the Magnetic Properties of
Liquid Oxygen." Friday evening discourse, bv Professor J. Dewar, F.R.S.

X Proc. Roy. Soe. vol. Ix. 1896, p. 283, " On the Magnetic Permeability of
Liqaid Oxygen and Liquid Air," by Professor J. A. Fleming, F.R.S. and
Professor J. Dewar, F.R.S.

1897.] on Properties of Liquid Oxygen. 559

susceptibility of which is to be determined. A second method con-
sists in determining the mechanical force acting on a known mass
of the liquid when placed in a non-uniform magnetic field. Owing
to the difficulty of preventing entirely the evaporation of liquid
oxygen, even when contained in a good vacuum vessel, and the im-
possibility of sealing it up in a bulb or tube, and having regard to the
effect of the low temperature of the liquid in deforming by contrac-
tion and altering the conducting power of coils of wire placed in it, it
was necessary to devise some method which should be independent of
the exact constancy in mass of the liquid gas operated upon, and in-
dependent also of slight changes in the form of any coils of wire
which might be used in it. After many unsuccessful preliminary
experiments the method which was finally adopted by Professor
Fleming and myself as best complying with the conditions introduced
by the peculiar nature of the substance operated upon is as fol-
lows : —

A small closed circuit transformer was constructed, the core of
which could be made to consist either of liquid oxygen or else imme-
diately changed to gaseous oxygen, having practically the same tem-
perature. This transformer consisted of two coils, the ^primary coil
was made of forty-seven turns of No, 12 S.W.G. wire ; this wire was
wound into a spiral having a rectangular shape, the rectangular
turns having a length of 8 cm. and a width of 1 • 8 cm. This rect-
angular-sectioned spiral, consisting of one layer of wire of forty-seven
turns, was bent round a thin brass tube, 8 cm. long and 2J cm. in
diameter, so that it formed a closed circular solenoid of one layer of
wire. The wire was formed of high conductivity copper, doubly in-
sulated with cotton, and each single turn or winding having a rect-
angular form.

The turns of covered wire closely touched each other on the inner
circumference of the toroid, but on the external circumference were
a little separated, thus forming apertures by which liquid could enter
or leave the annular inner core.

The nature of this transformer is shown in Fig. 1.

The mean perimeter of this rectangular-sectioned endless solenoid
was 13J cm. and the solenoid had, therefore, very nearly 3*5 turns
per cm. of mean perimeter. When immersed in liquid oxygen a coil
of this kind will carry a current of 50 amperes. When a current of
A amperes is sent through this coil the mean magnetising force in
the axis of this solenoid is, therefore, represented by 4*376 times the
current through the wire, hence it is clear that it is possible to produce
in the interior of this solenoid a mean magnetising force of over
200 C.G.S. units. This primary coil had then wound over it, in two
sections, about 400 or 500 turns of No. 26 silk-covered copper wire to
form a secondary coil. The primary and secondary coils were sepa-
rated by layers of silk ribbon. The exact number of turns was not
counted, and, as will be seen from what follows, it was not necessary
to know the number. The coil so constructed constituted a small

560 Professor Dewar [Jan. 22,

induction coil or transformer, with a closed air-core circuit, but which,
when immersed in a liquid, by the penetration of the liquid into the
interior of the primary coil, became changed into a closed circuit
transformer, with a liquid core. The transformer so designed was
capable of being placed underneath liquid oxygen contained in a
largo vacuum vessel, and when so placed formed a transformer of the
closed circuit type, with a core of liquid oxygen. The coefficient of
mutual induction of these two circuits, primary and secondary, is

Fig. 1. — Diagram of the Closed Circuit Transformer used in Experiments.

therefore altered by immersing the transformer in liquid oxygen,
but the whole of the induction produced in the interior of the
primary coil is always linked with the whole of the turns of the
secondary coil, and the only form-change that can be made is a small
change in the mean perimeter of the primary turns due to the con-
traction of the coil as a whole. In experiments with this transformer
the transformer was always lifted out of the liquid oxygen into the
cold gaseous oxygen lying on the surface of the liquid oxygen, and

1897.] on Properties of Liquid Oxygen, 561

which is at the same temperature. On lifting out the transformer,
the liquid oxygen drains away from the interior of the primary coil,
and is replaced by gaseous oxygen of very nearly the same tem-
perature.

The vacuum vessel used had a depth of 60 cm. outside and 53 cm.
inside, and an internal diameter of 7 cm. It held 2 litres of liquid
oxygen when full ; but, as a matter of fact, 4 or 5 litres of liquid
oxygen were poured into it in the course of the experiment.

Another induction coil was then constructed, consisting of a long
cylindrical coil wound over the four layers of wire, and a secondary
circuit was constructed to this coil, consisting of a certain number of
iurns wound round the outside of the primary coil, and a small
adjusting secondary coil, consisting of a thin rod of wood wound over
with very open spirals of wire. The secondary turns on the outside
of the primary coil were placed in series with the turns of the thin
adjusting coil, and the whole formed a secondary circuit, partly out-
side and partly inside the long primary cylindrical coil, the coefficient
of mutual induction of this primary and secondary coil being capable
of being altered by very small amounts by sliding into or out of the
primary coil the small secondary coil. This last induction coil, which
will be spoken of as the balancing coil, was connected up to the small
transformer, as just described, as follows : —

The primary coil of the small transformer was connected in series
with the primary coil of the balancing induction coil, and the two
terminals of the series were connected through a reversing switch
and ammeter with an electric supply circuit, so that a current of
known strength could be reversed through the circuit, consisting of
the two primary coils in series. The two secondary coils, the one on
the transformer and the one on the balancing induction coil, were con-
nected in opposition to one another through a sensitive ballistic
galvanometer in such a manner that on reversing the primary
current the galvanometer was affected by the difference between the
electromotive forces set up in the two secondary coils, and a very fine
adjustment could be made by moving in or out the adjusting coil of
the balancing induction coil.

The arrangement of circuits is shown in Fig. 2.

For the purpose of standardising the ballistic galvanometer
employed, the primary coil of the balancing induction coil could
be cut out of circuit, so that the inductive effect in the ballistic
galvanometer circuit was due to the primary current of the closed
circuit transformer alone. A resistance box was also included in the
circuit of the ballistic galvanometer. The resistance of the ballistic
galvanometer was about 18 ohms, and the resistance of the whole
secondary circuit 80 '36 ohms. The experiment then consisted in
first balancing the secondary electromotive forces in the two coils
exactly against one another, then immersing the transformer in liquid
oxygen, the result of which was to disturb the inductive balance, and
in consequence of the magnetic permeability of the liquid oxygen core

562

Professor Dewar

[Jan. 22,

being greater tlian unity, a deflection of the ballistic galvanometer
was observed on reversing the same primary current. The induction
through the primary circuit of the small transformer is increased in
the same proportion that the permeability of the transformer core
is increased by the substitution of liquid oxygen for gaseous oxygen,
and hence the ballistic deflection measures at once the amount by
which the magnetic permeability of the liquid oxygen is in excess
over that of the air or gaseous oxygen forming the core of the trans-
former when the transformer is lifted out of the liquid. As a matter
of fact, it was never necessary to obtain the inductive balance pre-

WWW
r\AAAA/\

Vwvw

r

Fig. 2. — Arrangement of the Circuits of the Transformer and Induction Coil.

cisely. All that was necessary was to observe the throw of the bal-
listic galvanometer, first when the transformer was wholly immersed
under the surface of liquid oxygen, and, secondly, when it was lifted
out into the gaseous oxygen lying on the surface of the liquid, the
strength of the primary current reversed being in each case the same.
In order to standardise the galvanometer and to interpret the mean-
ing of the ballistic throw, it was necessary to cut out of circuit
the primary coil of the balancing induction coil, and to reverse
through the primary circuit of the small transformer a known small
primary current, noting at the same time the ballistic throw pro-
duced on the ballistic galvanometer, this being done when the
transformer was underneath the surface of liquid oxygen. It will
be seen, therefore, that this method requires no calculation of any

1897.]

on Properties of Liquid Oxygen,

563

coefficient or mutual induction, neither does it involve any know-
ledge of the number of secondary turns on the transformer, nor of
the resistance of the secondary circuit ; all that is necessary for a
successful determination of the magnetic permeability of the liquid
oxygen is that the secondary circuit of the transformer should
remain practically of the same temperature during the time when
the throw of the ballistic galvanometer is being observed, both
with the transformer underneath the liquid oxygen and out of the
liquid oxygen. If then the result of reversing a current of A
amperes through the two primary coils in series when the secondary
coils are opposed is to give a ballistic throw D, and if the result of
reversing a small current a amperes through the primary coil of the
transformer alone is to produce a ballistic throw d, then, if fx is the
magnetic permeability of liquid oxygen, that of the gaseous oxygen
lying above the liquid and at the same temperature being taken as
unity, we have the following relation : —

D

a
•which determines the value of /x.

Table op Results of Observations on the Magnetic Permeabilitt of
Liquid Oxygen.

A = primary
current, in
amperes, passing
through pri-
maries of the
tran?former and
balancing coil.

Corresponding

mean mag-
netisng force in
C.G.S. units in
primary circuit
of transformer.

Total ballistic
throw which would

be produced if
primary current of
A amperes were
reversed through
primary of trans-
former alone

= ^-

Ballistic throw

of Kalvanometer

resulting from

immersion of the

transformer in

liquid oxygen.

Transformer and

balancing

induction coil

being opposed

IX = permeability ;
calculated from

8-037
28-18
37-8
36-8
50-5

35-2
123-0
165-4
161-0
220-9

1,734

6,068

8,153

7,938

10,894

4-33
14-9
21-18
23-57

32-98

1-00250
1-00246
1-00260
1-00297
1-00304

The values of the permeability given in the foregoing table are not
all of equal weight.

The value, viz. !• 00287, found by Professor Fleming and the
author for the magnetic permeability of liquid oxygen, shows that
the magnetic susceptibility {Jc) per unit of volume is 228/ 10^ It
is interesting to compare this value with the value obtained by

564: Prof. Deivar on Properties of Liquid Oxygen. [Jan. 22, '97.

Mr. Townsend for an aqueous solution of ferric chloride, and which
he states can be calculated by the equation

10'k = 91-6m>- 0-77,

where w is the weight of salt in grams per cubic centimetre, and Jc
the magnetic susceptibility. Even in a saturated solution, w cannot
exceed 0 * 6, hence, from the above equation, we find the value of the
magnetic susceptibility of a saturated solution of one of the most para-
magnetic iron salts, viz. ferric chloride, is 54/10^ for magnetic forces
between 1 and 9. This agrees fairly well with other determinations
of the same constant. On the other hand, the magnetic suscepti-
bility of liquid oxygen for the same volume is 228/10^ or more than
four times as great. The unique position of liquid oxygen in respect
of its magnetic susceptibility is thus strikingly shown. It is, how-
ever, interesting to note that its permeability lies far below that of
certain solid iron alloys generally called non-magnetic.

In the course of these investigations valuable assistance has been
given by Mr. Robert Lennox and Mr. J. W. Heath.

I J. D.]

LOKPon: printed by William clowes and sons, limited,
stamfokd street and charing cboss,

fl0gal Jnatituticn nf (Bxtai ?Sntj

'Q>

WEEKLY EVENING MEETING, ^s<^

Friday, January 21, 1898*

Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Honorary
Secretary and Vice-President, in the Chair.

The Eight Hon. Sir John Lubbock, Bart, M.P. D.C.L. LL.D.

F.R.S. M.n.i.

^^ Buds and Stipules,

The lecturer commenced by saying that his attention had been drawn
to the subject by a remark of Vaucher's in his ' Histoire Physiologique
des Plaiites,' calling attention to the fact that some species of Kock-
rose have stipules \Yhile others have none, and suggesting that it
would be interesting, if possible, to determine the reason for the
difference. Stipules are the small leaflets found at the base of the
leaf in many plants. In some they drop early, so that on a cursory
examination they might be supposed to be absent, as, for instance, in
the Beech or Elm; in others they live as long as the leaves, and in
some few cases even survive them. The study of stipules led him
to that of buds.

Every gardener knows to his cost how often the bright promise
of spring is ruined by late frosts. All through the winter the young
leaves, which commenced in the previous year and are formed in the
bud even early in the previous summer, lie snugly enclosed in many
warm wraps, covered, moreover, by furry hairs, and often still further
protected from insects and browsing quadrupeds by gummy secre-
tions.

A complete leaf may be considered as consisting of four parts,
the blade, the leaf-stalk, the stipules and the leaf-base ; or perhaps
of two portions : the upper, with its expansion, forming the blade ;
and the lower, with two ajipendages, the stipules. Sometimes the
stipules are absent, as in Ma23les ; sometimes the leaf-stalk is absent,
as in Gentians ; sometimes the blade is absent, and its function is
performed by the flattened petiole, as in most of the Australian
Acacias ; sometimes the stipules alone are present, as in a very
curious Pea, Lathyrus Aphaca.

He then described a number of different forms of stipules and the
construction of buds in a variety of common shrubs and trees. In
the Oak the bud has over forty coverings before a normal leaf is
reached, and the peculiar form of the leaf-blade is due to the way it is
packed in the bud. He showed the leaves and flowers of the coming

Vol. XV. (No. 92.) 2 p

566 Bight Hon. Sir J. Luhhoch on Buds and Stipules. [Jan. 21,

Bummer, and in the Pine even the rudiments of the leaves of the
following year. He showed in some cases how the form of the bud
influenced the leaves, pointing out that the seed-leaves, or cotyledons,
differ from the subsequent leaves mainly because they are influenced,
not by the form of the bud, but by that of the seed, and showed for
instance how the form of the seed-leaf in the Mustard and other
plants was thus determined.

In conclusion, he described the fall of the leaf, which is a vital
process, and not merely one of death. Finally, he showed in the
Rock-roses that those species in which the young bud is protected by
a broad petiole have no stipules, while those in which the petiole is
narrow are provided with stipules, which serve for the protection of
the bud.

Thus then, he said in conclusion, I have endeavoured to answer
Yaucher's question, to explain at any rate in some cases the presence,
the uses and the forms of stipules, and the structure of buds in some
of our common trees, shrubs and herbs. If I shall have induced you
to look at them for yourselves in the coming spring, you will be
amply rewarded.

You will often be reminded of Tennyson's profound remark about
Nature :

" So careless of the single life,
So careful of the type she seems,"

and you will, I am sure, be more and more struck with wonder and
admiration at the variety and beauty of the provisions by which
Nature preserves these tender and precious buds from the severity of
winter, and prepares with loving care and rich profusion for the
bright promise of spring and the glorious pageant of summer.

1898.] Instinct and Intelligence in Animals. 567

WEEKLY EVENING MEETING,

Friday, January 28, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer
and Vice-President, in the Chair.

Professor C. Lloyd Morgan, F.G.S. Principal of
University College, Bristol,

Instinct and Intelligence in Animals.

Biology is a science, not only of the dead, but of the living. The
behaviour of animals, not less than their form and structure, demands
our careful study. Both structure and behaviour are, however, de-
pendent on that heredity which is a distinguishing characteristic of
the organic world, and in each case heredity has a double part to
play. It provides much that is relatively fixed and stereotyped, but
it provides also a certain amount of plasticity, or ability to conform to
the modifying conditions of the environment. Instinctive behaviour
belongs to the former category ; intelligent behaviour to the latter,.
When a caterpillar spins its silken cocoon, unaided, untaught and
without the guidance of previous experience ; or when a newly-mated
bird builds her nest and undertakes the patient labours of incuba-
tion, before experience can have begotten anticipations of the coming
brood, we say that the behaviour is instinctive. But when an animal
learns the lessons of life and modifies its procedure in accordance
with the results of its individual experience, we no longer use the
term instinctive, but intelligent. Instinct, therefore, comprises those
phases of active life which exhibit such hereditary definiteness as fits
the several members of a species to meet certain oft-recurring or
vitally important needs. To intelligence belong those more varied
modes of procedure which an animal adopts in adaptation to the
peculiar circumstances of its individual existence. Instinctive acts
take their place in the class of what are now generally known as
congenital characters; intelligent acts in the class of acquired
characters.

But the study of instinct and intelligence in animals opens up
problems in a different field of scientific investigation. They fall
within the sphere not only of biological, but also of psychological
inquiry. And in any adequate treatment of their nature and origin,
we must endeavour to combine the results reached by different methods
of research in one harmonious doctrine. This involves difiiculties
both practical and theoretical. For those invertebrates, such as the
insects, which to the naturalist present such admirable examples of

2 p 2

568 Professor C. Lloyd Moi-gan [Jan. 28,

instinctive behaviour, are animals concerning wliose mental processes
the cautious psychologist is least disposed to express a definite opinion.
While the higher mammalia, with whose psychology we can deal
•with greater confidence, exhibit less typical instinctSj are more sub-
ject to the disturbing influence of imitation, and, from the greater
complexity of their behaviour, present increased difficulties to the
investigator who desires carefully to distinguish what is congenital
from what is acquired.

Nor do the difficulties end here. For the term "instinct" is
commonly, and not without reason, employed by psychologists with
a somewhat different significance, and in a wider sense than is neces-
sary or even desirable in biology. The naturalist is concerned only
with those types of behaviour which lie open to his study by the
methods of direct observation. He distinguishes the racial adapta-
tion which is due to congenital definiteness, from that individual
accommodation to circumstances which is an acquired character.
But for the psychologist, instinct and intelligence comprise also the
antecedent conditions in and through which these two types of animal
activity arise. The one type includes the conscious impulse, which
in part determines an instinctive response; the other includes the
choice and control which characterise an intelligent act. When a
spider spins its silken web, or a stickleback builds the nest in which
his mate may lay her eggs, the naturalist describes the process and
seeks its origin in the history of the race ; but the psychologist in-
quires also by what impulse the individual is prompted to the per-
formance. And when racial and instinctive behaviour is modified in
accordance with the demands of special circumstances, the naturalist
observes the change and discusses whether such modifications are
hereditary ; but the psychologist inquires also the conditions under
which experience guides the modification along specially adaptive
lines. Each has his part to play in the complete interpretation of
the facts ; and each should consent to such definitions as may lead
to an interpretation which is harmonious in its results.

In view, therefore, of the special difficulties attendant on a com-
bined biological and psychological treatment of the problems of
animal behaviour, I have devoted my attention especially to some
members of the group of birds in the early days of their life, and
I shall therefore draw my examples of instinct and intelligence
almost entirely from this class of animals. The organisation and
the sensory endowments of birds are not so divergent from those of
man, with whose psychology alone we are adequately conversant,
as to render cautious conclusions as to their mental states altogether
untrustworthy ; when hatched in an incubator they are removed from
that parental influence which makes the study of the behaviour of
mammals more difficult; while the highly developed condition in
which many of them first see the light of day affords opportunity
for observing congenital modes of procedure under more favourable
circumstances than are presented by any other vertebrate animals.

1898.] on Instinct and Intelligence in Animals. 569

Even with these specially selected subjects for investigation, however,
it is only by a sympathetic study and a careful analysis of their
behaviour that what is congenital can be distinguished from what is
acquired ; for from the early hours of their free and active life, the
influence of the lessons taught by experience makes itself felt. Their
actions are the joint product of instinct and intelligence, the con-
genital modes of behaviour being liable to continual modification in
adaptation to special circumstances. Instinct appears to furnish a
ground plan of procedure, which is shaped by intelligence to the
needs of individual life, and it is often hard to distinguish the
original instinctive plan from the subsequent intelligent modification.

It is not my purpose to describe here in detail, as I have done
elsewhere, the results of these observations. It will suffice to indicate
some of the more salient facts. In the matter of feeding the callow
young of such birds as the jackdaw, jay or thrush instinctively open
wide their beaks for the food to be thrust into their mouths. Before
the eyes have opened, the external stimulus to the act of gaping would
seem to be either a sound or the shaking of the nest when the parent
bird perches upon it. Under experimental conditions, in the absence
of parents, almost any sound, such as a low whistle, lip-sound, or click
of the tongue, will set the hungry nestlings agape, as will also any
shaking or tapping of the box which forms their artificial nest. And
no matter what is placed in the mouth the reflex acts of swallowing
are initiated. But even in these remarkably organic responses the
influence of experience soon makes itself felt. For if the material
given is wrong in kind or distasteful, the effect is that the bird ceases
to gape as before to the stimulus. Nor does it continue to open the
beak when appropriate food has been given to the point of satisfac-
tion. These facts show that the instinctive act is prompted by an
impulse of internal origin, hunger, supplemented by a stimulus of
external origin, at first auditory, but later on, when the eyes are
opened, visual. They show also that when the internal promptings
of hunger cease, owing to satisfaction, the sensory stimulus by itself
is no longer operative ; and they show, too, that the diverse acts of
gaping and swallowing become so far connected that the experience
of distasteful morsels tends, for a while at least, to prevent further
gaping to the usual stimulus.

With those birds which are active and alert soon after hatching,
the instinctive acts concerned in feeding are of a different character.
At first, indeed, the chick does not peck at grains which are placed
before it, and this is probably due to the fact that the promptings of
hunger do not yet make themselves felt, there being still a considerable
supply of unabsorbed yolk. Soon, however, the little bird pecks with
much, but not quite perfect, accuracy at small near objects. But
here again experience rapidly plays its part. For if distasteful
objects, such as bits of orange peel, are the first materials given,
pecking at them soon ceases; and if this be repeated the little bird
cannot be induced to peck, and may even die of starvation. This

570 Frofeasor C. Lloyd Morgan [Jan. 28,

makes it very difficult to rear by hand some birds, sucb as plovers,
whose natural food, in due variety, is not readily obtainable. It must
be remembered, too, that under natural conditions the parent bird
calls the young and indicates with her beak the appropriate food;
and this appears to afford an additional stimulus to the act of pecking.
Pheasants and partridges seem to be more dependent on this parental
guidance than domestic chicks, and they are more easily reared when
they have somewhat older birds as models, whose pecking they may
imitate. Passing allusion may here be made to a type of instinctive
response in some respects intermediate between the upward gaping of
the jay and the downward pecking of the chick. It is seen in the
young moorhen, which pecks upwards at food held above it, and can-
not at first be induced to take any notice of food on the ground.
Under natural conditions it is fed by the parent, which holds the
food in her beak above the little bird as it floats on the water.

We have, then, in these simple instinctive acts examples of behaviour
which is congenitally definite in type for each particular species ; of
actions which are the joint product of an internal factor, hunger, and
an external factor, sensory impressions; of complex modes of pro-
cedure which subserve certain vital needs of the organism. It should
be mentioned, however, that the relative definiteness of instinctive
responses has been subjected to criticism from a psychological source.
It has been urged that the nutritive instincts, the play instincts, the
parental instincts, those of self-preservation, and those concerned in
reproduction, are so varied and multifarious that definiteness is the
last thing that can be predicated of them. Varied and multifarious
they are indeed, and each of the groups above mentioned contains
many differing examples ; but that is because we are dealing with
comprehensive classes of instinctive behaviour. The fact that the
group of fishes includes organisms of such wide structural diversity
as the salmon, the globe fish, the eel and the sole, does not affect the
fact that these species have a relatively definite structure each after
his kind. It is only when we treat a group of fishes as if it were an
individual fish that we are troubled by iudefiniteness of structure.
And it is only when we deal with a group of instincts comprised
under a class-name as if it were a particular instinctive act, that we
fail to find that definiteness which to the naturalist is so remarkable.
From the physiological jDoint of view, instinctive procedure would
Beem to have its origin in an orderly group of outgoing neural dis-
charges from the central office of the nervous system, giving rise to a
definite set of muscular contractions. And this appears to have an
organic basis in a congenital preformation in the nervous centres, the
activity of which is called into play by incoming messages, both from
internal organs in a state of i^hysiological need, and from the external
world through the organs of special sense. The naturalist fixes his
attention chiefly on the visible behaviour, which is for him the
essential feature of the instinctive act. But in view of the require-
ments of psychological interpretation it is advisable to comprise under

1898.] on Instinct and Intelligence in Animals. 571

the term instinct, in any particular manifestation off its existence, tbe
net result of four things : first, internal messages gi ving rise to the
impulse ; secondly, the external stimuli which co-operate with the
impulse to aflfect the nervous centres ; thirdly, the active response due
to the co-ordinated outgoing discharge ; and fourthly, the message
from the organs concerned in the behaviour by which the central
nervous system is further aflfected. Now I shall here assume, without
pausing to adduce the arguments in favour of this view, that conscious-
ness is stirred in the brain only by incoming messages. If this be so,
the outgoing discharges which produce the behaviour are themselves
unconscious. Their function is to call forth adaptive movements ;
and these movements give rise to messages which, so to speak, afford
to consciousness information that the instinctive act is in progress.
Hence I have urged that the instinctive performance is an organic
and unconscious matter of the purely physiological order, though its
effects are quickly communicated to consciousness in the form of
definite messages from the motor organs. I have not denied that
the stimuli of sight, touch, hearing, and so forth, have conscious
efiects ; I do not deny (though here I may have spoken too guardedly)
that the initiating impulse of internal origin is conscious. In both
these cases we have messages transmitted to the central office of the
brain. What I have ventured to urge is that the consciousness of
instinctive behaviour, in its comjpleted form, does not arise until
further messages come in from the motor organs implicated in the
performance of the act, lodging information at the central office con-
cerning the nature of the movement. A diagram will perhaps serve to
make this conception clearer.

Impulse

Stimulus

Instinctive behaviour

The circle represents the brain, in some part of which conscious-
ness arises through the effects of incoming nerve-currents. Under
the influence of the two primary groups of messages due to impulse
and to sensory stimulus, consciousness is evoked, and the brain is
thrown into a state of neural strain, which is relieved by the outgoing
discharge to the organs concerned in the instinctive behaviour. It is
this outgoing discharge which I regard as unconscious. But the
acti(ms which are thus produced give rise to a secondary group of
incoming messages from the moving limbs. This it is which gives
origin to the consciousness of instinctive behaviour as such. And I
regard it as psychologically important that these incoming messages
are already grouped so as to afford to consciousness information
rather of the net results of movement than of their subsidiary details.

572 Professor C. Lloyd Morga7i [Jan. 28,

So much for our general scheme. If now we turn to the instinctive
behaviour concerned in locomotion, we find a congenital basis upon
which the perfected activities are founded. There is on the part of
the chick no elaborate process of learning to walk ; ducklings and
moorhens a few hours old swim with perfect ease when they are
placed in water ; these birds also dive without previous practice or
preliminary abortive attempts ; while young swallows, if their wings
are sufficiently large and strong, are capable of short and guided
flights the first time they are committed to the air. In these cases
neither the internal impulse nor the sensory stimuli are so well
defined as in that of the nutritive activities. The impulse probably
takes the form of an uneasy tendency to be up and doing, perhaps due
to ill-defined nervous thrills from the organs of locomotion, which are
in need of exercise. The sensory stimuli are presumably afibrded by
the contact of the feet with the ground or with the water, and by the
pressure of the air on the wing surfaces. It is a curious fact that if
joung ducklings be placed on a cold and slippery surface, such as
that of a japanned tea tray, they execute rapid scrambling movements
suggestive of attempts to swim, which I have never seen in chicks,
pheasants or other laud birds.

It will not be supposed that I claim for perfected locomotion, so
admirably exemplified in the graceful and powerful flight of birds, an
origin that is wholly instinctive and unmodified by the teachings of
experience. Here, as elsewhere, instinct seems to form the ground plan
of activities, which intelligence moulds to finer and more delicate
issues. This is the congenital basis on which is built the perfected
superstructure. And if our opjjortunities for observation and our
methods of analysis were equal to the task, we should be able to dis-
tinguish, in the development of behaviour, the congenital outline from
the shading and detail which are gradually filled in by the pencil of
experience.

The difficulties which render this analysis at the' best imperfect
are therefore twofold. In the first place, intelligence begins almost
at once to exercise its modifying influence ; and in the second place,
many instinctive traits do not appear until long after intelligence has
begun its work. Much of the intelligent detail of the living picture
is filled in before the instinctive outlines are complete. The term
*' deferred instincts " has been applied to those congenital modes of
procedure which are relatively late in development. The chick does
not begin to scratch the ground, in the manner characteristic of rasorial
birds, till it is four or five days old, nor does it perform the operation
of sand- washing till some days later ; the moorhen does not begin to
flick its tail till it is about four weeks old ; the jay does not perform
the complex evolutions of the bath till it has left the nest and felt its
legs, when the stimulus of water to the feet, and then the breast,
seems to start a train of acts which, taken as a whole, are of a remark-
ubly definite type. The development of the reproductive organs brings
with it, apart from the act of pairing, a number of associated modes of

1898.] on Instinct and Intelligence in Animals. 573

behaviour — nest building, incubation, song, dance, display, and strange
aerial evolutions — which are presumably, in large degree, instinctive,
though of this we need more definite evidence ; for it is difficult to esti-
mate, with any approach to accuracy, the influence of imitation. There
seems to be no reason for doubting that, when an animal grows up in
the society of its kind, it is affected by what we may term the tra-
ditions of its species, and falls into the ways of its fellows, its imitative
tendency being subtly influenced by their daily doings. The social
animal bears the impress of the conditions of its peculiar nurture.
Its behaviour is in some degree plastic, and imitation helps it to
conform to the social mould.

The exact range and nature of the instinctive outline, indepen-
dently of those modifications of plan which are due to the inherent
plasticity of the organism, are therefore hard to determine. And if,
as we have good grounds for believing, the growth of intelligent plas-
ticity, in any given race, is associated with a disintegration of the
instinctive plan, congenital adaptation being superseded by an accom-
modation of a more individualistic type, to meet the needs of a more
varied and complex environment, the problems with which we have to
deal assume an intricacy which at present defies our most subtle analysis.

We must now turn to the consideration of the manner in which
individual accommodation, through the exercise of intelligence under
the teachings of exj^erience, is brought about ; and it will be well
to pave the way by adducing certain facts of observation.

Although the pecking of a young chick, under the joint influence
of hunger and the sight of a small near object, would seem to belong
to the instinctive type, the selection of appropriate food, apart from
the natural guidance of the hen, seems to be mainly determined by
individual experience. There is no evidence that the little bird
comes into the world with anything like hereditary knowledge of good
and evil in things eatable. Distasteful objects are seized with not
less readiness than natural food, such as grain, seeds and grubs. The
conspicuous colours of certain nasty caterpillars do not appeal to any
inherited power of immediate discrimination, so as to save the bird
from bitter experience. They seem rather to serve the purpose of
rendering future avoidance, in the light of this bitter experience, more
ready, rapid and certain. Bees and wasps are seized with neither
more nor less signs of fear than large flies or palatable insects. Nor
does there seem to be any evidence of the hereditary recognition of
natural enemies as objects of dread. Pheasants and partridges showed
no sign of alarm when my dog quietly entered the room in which they
were kept. When allowed to come to closer quarters, they impudently
pecked at his claws. A two-days chick tried to nestle down under
him. Other chicks took no notice of a cat, exhibiting a complete in-
difference which was not reciprocated. A moorhen, several weeks old,
would not suffer my fox-terrier to come near his own breakfast of
Bopped biscuit, but drove him away with angry pecks until the higher
powers supervened.

674 Professor C. Lloyd Morgan [Jan 28,

It is not, of course, to be inferred from these observations tbat
sucb an emotion as fear has no place in the hereditary scheme, or
that the associated acts of hiding, crouching or efforts to escape, do
not belong to the instinctive type. I have seen little pheasants
struck motionless, plovers crouch, and moorhens scatter, at the sound
of a loud chord on the violin, or of a shrill whistle. A white stone-
ware jug, placed in their run, caused hours of uneasiness to a group
of birds including several species. But there is no evidence that, in
such cases, anything like hereditary experience defines those objects
which shall excite the emotion. It is the unusual and unfamiliar
object, especially after some days of active life amid surroundings to
which they have grown accustomed ; it is the sudden sound (such as a
sneeze), or rapid movement, as when a ball of paper is rolled towards
them, that evokes the emotion. Hence, if the parent birds are absent,
the stealthy approach of a cat causes no terror in the breast of inex-
perienced fledgelings. But when she leaps, and perhaps seizes one
for her prey, the rest scatter in alarm, and for them the sight of a
cat has in the future a new meaning.

The elementary emotions of fear, anger, and so forth, stand in
a peculiar and special relationship to instinct. At first sight they
seem to take rank with the internal impulses which are the part-
determinants of instinctive behaviour. The crouching of a frightened
plover or land-rail, the dive of a scared moorhen, result partly from
the external stimulus afforded by the terrifying object, partly from
the emotional state which that object calls forth. But in their pri-
mary genesis I am disposed — here following to some length the lead of
Professor Wm. James — to assign to such emotions an origin similar to
that of the consciousness which follows on the execution of the in-
stinctive act. Assuming, as before, that consciousness owes its genesis
to messages which reach the sensorium through incoming nerve-chan-
nels, the sensory stimuli, afforded, let us say, by the sight of a terri-
fying object, do not seem, in the absence of inherited experience,
capable of supplying messages which in themselves are sufficient to
generate the emotion of fear. Now the well known accompaniments
of such an emotional state are disturbances of the heart-beat, the
respiratory rhythm, the digestive processes, the action of the glands,
and the tone of the minute blood vessels throughout the body. And
all these effects are unquestionably ^produced by outgoing discharges
from the central nervous system. But they are felt as the result of
incoming messages, like vague and disquieting rumours, transmitted
to the central office from the fluttering heart, the irregular breathing,
the sinking stomach, and the disturbed circulation. Is it not there-
fore reasonable to suppose that the emotion in its primary genesis, is
due to the effect on the sensorium of these disquieting messages ? If
this be admitted as a working hypothesis — and it cannot at present
claim to be more than this — we reach at any rate a consistent scheme.
As primary messages to the central office of consciousness we have,
on the one hand those due to stimuli of the special senses, and on the

1898.] on Instinct and Intelligence in Animals, 675

other hand those resulting from the condition of the bodily organs,
taking the form of a felt craving for their appropriate exercise. These
co-operate to throw the brain into a state of unstable equilibrium, or
neural strain, which is relieved by outgoing streams of nervous energy.
And these in turn fall into two groups : first, an orderly set of
discharges to the voluntary muscles concerned in behaviour; and
secondly, a more diifuse group of discharges to the heart, resj)iratory
api)aratus, digestive organs, glands and vascular network. In so far as
these are outgoing discharges, they do not directly affect consciousness.
But there quickly returns upon the sensorium an orderly group of
incoming messages from the motor apparatus concerned in instinctive
behaviour, and a more indefinite group from the heart and other
visceral organs. The former gives the well-defined consciousness of
activity, the latter the relatively ill-defined feelings which are classed
as emotional. But so swift is the back-stroke from the body to the
brain, that, ere the instinctive behaviour is complete, messages from
the limbs — and, under the appropriate circumstances, from the heart
— that is to say, of both instinctive and emotional origin — begin to
be operative in consciousness ; and the final stages of a given per-
formance may be guided in the light of the experience gained during
its earlier stages.

The exact manner in which consciousness exercises its guiding
influence is a matter of speculation. Perhaps the most probable
hypothesis is that the central hemispheres are an adjunct to the rest
of the central nervous system, and exercise thereon, by some such
mechanism as the pyramidal tract in the human subject, a controlling
influence. Given an hereditary ground plan of automatic and in-
stinctive responses, the cerebral hemispheres may, by checking here
and enforcing there, limit or extend the behaviour in definite ways.
In any case, from the psychological point of view, their action is
dependent on three fundamental properties : first, the retention of
modifications of their structure ; secondly, difierential results accord-
ing as these modifications have pleasurable or painful accompaniments
in consciousness ; and thirdly, the building of the conscious data,
through association, into a system of experience. The controlling
influence of this experience is the essential feature of active intelli-
gence. Or, expressed in the almost obsolete terminology of the older
psychology, intelligence is the faculty through which past inexperi-
ence is brought to bear on present behaviour.

Professor Stout, whose careful work in analytical psychology is
well known, has done me the service of criticising, in a private com-
munication, my use of the phrase " past experience," urging that
present experience is not less important in determining behaviour
than that which is past, and which can only be operative through its
revival in memory. The criticism is valid in so far as it shows that
I have not been sufficiently careful to define what I mean by past
experience. But I certainly had in mind, though I did not clearly
indicate, the inclusion of what Mr. Stout regards as present ex-

576 Professor C. Lloyd Morgan [Jan. 28,

perience. My conception of " present," as I have elsewhere described
it, is that short but appreciable period of time, occupying only some
small fraction of a second, which is comprised in the fleeting moment
of consciousness. All anterior to this, if it were but a second ago,
I regard as past — past, that is to say, in origin, though still operative
in the limited field of the present moment. When we are reading a
paragraph and near its close, the net result of all that we have read
in the earlier sentences is present to influence the course of our
thought. But the very words — " all that we have read " — by which
we describe this familiar fact, imply that the guiding experience
originated in a manner which demands the use of the past tense.
Still I am none the less grateful to Mr. Stout for indicating what to
many may have seemed a serious omission in my interpretation.
Sufiice it to say that if we include under the phrase " present ex-
perience " the occurrences of five minutes or even of five seconds ago
(all of which I regard as past), I fully agree that present experience
(in this sense) exercises a most important guiding influence.

We have distinguished four classes of messages afi'ecting con-
sciousness in the central office of the sensoriura : first, stimuli of the
special senses ; secondly, internal cravings ; thirdly, motor sensations
due to bodily activity ; and fourthly, emotional states. These are
combined in subtle synthesis during the growth of experience, and
are associated together in varied ways. Into the manner in which
experience grows we cannot enter here. It will be sufficient to
indicate very briefly the effects of this growth on the behaviour of
animals in the earlier stages of their life. This may be considered
from a narrower or from a broader standpoint. In the narrower view
we watch how, within the field of widening synthesis, particular
associations are formed. We see how, within experience, the taste
and appearance of certain caterpillars or grubs become so associated
that for the future the larva is left untouched. Or we see how that
terrible pounce of the cat becomes so associated with her appearance
as thenceforth to render her an object of dread to enlightened spar-
rows. But of the physiological mechanism of association we know
little.

There is a familiar game in which a marble is rolled down an
inclined board at the bottom of which are numbered compartments.
The lower part of the board is beset with a series of vertical pins so
arranged that the marble, rebounding from one to another, pursues
a devious course before it reaches its destination. But if we tie
threads from pin to pin we may thus direct the course of the marble
along definite lines. Now the brain may be roughly likened to a
set of such pins, and the marble to an incoming nerve current. The
congenital structure is such that a number of hereditary threads con-
nect the pins in definite ways, and direct the discharge into appro-
priate channels. But a vast number of other threads are acquired
in the course of individual experience. These are the links of
association which direct the marble in new ways. Observation of

1898.] on Instinct and Intelligence in Animals. 577

behaviour can only give us information that new directing threads
have been introduced. The psychology of association can only
indicate which pins have been connected by linking threads. Even
such researches as those of Flechsig can at present do no more than
supplement the psychological conclusion by general anatomical
evidence. Of the details of brain modification by the formation of
association fibres we are still profoundly ignorant.

Nor when we turn from the narrower to the wider point of view are
we in better case. We are forced to content ourselves with those
generalities which are the makeshift of imperfect knowledge. Still
even such generalities are of use in showing the direction in which
more exact information is to be sought. And we can, perhaps, best
express the net result of acquired modification of brain-structure by
saying that every item of experience makes the animal a new being,
with new reactive tendencies. The sparrows, which yesterday were
unaffected by the stealthy approach of the cat, garrulously scatter to-
day, because they are not the same simple-minded sparrows that they
were. The chick comes into the world possessed of certain instinctive
tendencies, with certain hereditary directing threads. But at the touch
of experience its needs are modified or further defined. New con-
necting threads are woven in the brain. On the congenital basis has
been built an acquired disposition. The chick is other than it was,
and reacts to old stimuli with new modes of behaviour.

In its early days, the developing animal is reading the paragraph
of life. Every sentence mastered is built into the tissue of experience,
and leaves its impress on the plastic yet retentive brain. By dint of
repetition the results of acquisition become more and more firmly in-
grained. Habits are generated, and habit becomes second nature.
The organism which, to begin with, was a creature of congenital im-
pulse and reaction, becomes more and more a creature of acquired
habits. It is a new being, but one with needs not less imperious than
those with which it was congenitally endowed.

All of this is trite and familiar enough. But it will serve its
purpose if it help us to realise how large a share acquired characters
take in the development of behaviour in the higher animals, and how
fundamentally important is the plasticity of brain-tissue, and its re-
tentiveness of the modifications which are impressed on its yielding
substance.

Such being the relations of intelligence to instinct in the indi-
vidual, what are their relations in the evolution of the race? Granting
that instinctive responses are definite through heredity, how has this
definiteness been brought about ? Has it been through natural
selection ? Or are the acquired modifications of one generation trans-
mitted through heredity to the next ? Is instinct inherited habit ?
Mr. Herbert Spencer has long advocated and still advocates the
latter view ; while Mr. A. E. Wallace attributes instinct entirely
to natural selection. Darwin, who wrote before the transmission of
acquired characters was seriously questioned, admitted both factors.

578 Professor 0. Lloijd Morgan [Jan. 28,

And Eomanes, to whose ever-kindly sympathy I am deeply indebted,
adhered to this view in spite of modern criticism. There is not much
in my own observational work which has any decisive bearing on the
question. But there are one or two points which are perhaps worthy
of consideration. The part played by acquisition in the field of
behaviour is the establishment of definite relations between particular
groups of stimuli and adaptive responses. If this be so, and if
acquired modifications of brain-structure be transmitted, we might
reasonably expect that the sight of a dog would have a similar effect
on young pheasants to that which it has on their parents. But this
does not appear to be the case. Again, one might reasonably expect
that the sight of water would evoke a drinking response in recently
hatched birds, just as the sight or scent of a Yucca flower excites a
definite response in the Yucca moth. But here, too, this is not so.
Thirsty chicks and ducklings seem to be uninfluenced by the sight
of water in a shallow tin. They may even run through the liquid
and remain unaffected by its presence. But if they chance to peck at
a grain at the bottom of the tin or a bubble on the water, as soon as
the beak touches the liquid, this stimulus at once evokes a drinking
response again and again repeated. Why does the touch of water in
the beak excite a congenital response, while the sight of water fails
to do so? I believe it is because under natural conditions the chicks
peck at tbe water in imitation of the mother, who thus shields them
from the incidence of natural selection. Under these circumstances
there is no opportunity for the elimination of those who fail to
respond at the mere sight of water, and consequently no selective
survival of those who do thus respond. Bat though the hen can
lead her young to peck at the water, she cannot teach them the
essential movements of beak, mouth and gullet which are necessary
for the completed act of drinking. In this matter she cannot shield
them from the incidence of natural selection. Those which, on
pecking the water, failed to respond to the stimulus by drinking,
would assuredly die of thirst and be eliminated ; the rest would
survive and transmit the congenital instinctive tendency. Thus it
would seem that when natural selection is excluded, a special mode
of behaviour has not become congenitally linked with a visual
stimulus ; but where natural selection is in operation, this behaviour
has become so linked with a touch or taste stimulus in the beak.
Similarly in the case of the pheasants and the dog. The parent birds
warn the young of his approach, and thus prevent the incidence of
natural selection. Hence there is no instinctive response to the sight
of a terrier.

No doubt there are many cases of complex behaviour, seemingly
instinctive, which are difficult to explain by natural selection alone,
and which have the appearance of being due to the inheritance of
acquired habits. I have, however, elsewhere suggested that acquired
modifications may, under the conditions of natural selection, foster
the development of " coincident " variations of like nature and direc-

1898.] on Instinct and Intelligence in Animals. 579

tion, but having their origin in the germinal substance. But into
a consideration of this hypothesis I cannot here enter. Without
assuming a dogmatic attitude, I am now disposed to regard the direct
transmission of acquired modes of behaviour as not proven.

Thus we come back to the position assumed at the outset — that
heredity plays a double part. It provides, through natural selection
or otherwise, an outline sketch of relatively definite behaviour, racial
in value ; it provides also that necessarily indefinite plasticity which
enables an animal to acquire and to utilise experience, and thus to
reach adaptation to the circumstances of its individual life. It
becomes therefore a matter of practical inquiry to determine the
proportion which the one kind of hereditary legacy bears to the other.
Observation seems to show that those organisms in which the en-
vironing conditions bear the most uniform relations to a mode of life
that is relatively constant, are the ones in which instinct preponder-
ates over intelligent accommodation ; while those in which we see
the most varied interaction with complex circumstances, show more
adaptation of the intelligent type. And the growth of individual
plasticity of behaviour in race development would seem to be accom-
panied by a disintegration of the definiteness of instinctive response,
natural selection favouring rather the plastic animal capable of
indefinitely varied accommodation than the more rigid type, whose
adaptations are congenitally defined.

I have dealt, it will be observed, only with the lower phases and
earlier manifestations of intelligence. Its higher development, and
the points in which it differs from the more complex modes of human
procedure, offer a wide and difiScult field for careful observation and
cautious interpretation. I have recently attempted further investiga-
tions in this field, but tliey concern rather the relation of intelligence
to logical thought than that of instinct to intelligence, which forms
the subject of this discourse.

[C. LI. M.]

680 Mr. Alan A. Campbell Swinton [Fob. 4,

WEEKLY EVENING MEETING,

Friday, February 4, 1898.

Sib William Crookes, F.R.S. Vice-President, in the Chair.

Alan A. Campbell Swinton, Esq. M.B.I.

Some New Studies in Cathode and Bontgen Radiations,

The researches of Crookes, Lenard and Routgen have given to man
a new eye. They have perhaps also given to nature a new light.
They have certainly given to science more than one new problem.

This small glass bulb which I hold in my hand, which, being ex-
hausted to a high vacuum, contains, besides its two aluminium elec-
trodes, only a few billions of molecules of residual gas, may appear but
a simple piece of apparatus. Could it, however, only be induced while
Tinder the stimulus of an electric discharge to reveal in their entirety
the secrets that it contains, we should know much at present utterly
unknown, not only as regards the nature of electrical action, but also
in reference to the funtlamental constitution of matter, and the
true mechanism of energy. It is, in fact, for the reason that within
the Crookes radiant-matter tube, where molecules are separated by
comparatively long distances, it is possible to deal not as in everyday
life with aggregates of matter, but even individually, perhaps, with
single molecules and atoms floating apart in space, that so much
attention is at present being devoted to this particular branch of
physics.

Every one is now acquainted with what has become the quite
ordinary phenomenon of the cathode rays. I turn on the induction
coil spark to this highly exhausted tube, and from the aluminium
plate that forms the negative electrode or cathode, there proceeds, as
you see, some kind of ray that excites a green luminescence in the
glass upon which it fall.*. I interpose in the path of these cathode
rays a screen, made of aluminium in the form of a cross, and the lattor
casts a sharp shadow on the glass. I have here a coil of wire,
through which an electric current is passing, and as I slowly move
the coil so as to encircle the tube, and consequently gradually increase
the strength of the magnetic field within the tube, it will be observed
that the shadow of the cross rotates, becoming at the same time
smaller. Here we obviously have a deflection of the cathode rays
from their rectilinear path, the action of a magnetic field of this
description being to concentrate the rays and also to give them a twist,
the direction of which depends upon the direction in which the current
is sent through the coil of wire.

1898.] on Some New Studies In Cathode and Eontgen Badiations. 581

This concentration or focnssing of the cathode rays by means of a
magnetic field, which has been studied by Biikeland and by Fleming,
can be also shown by means of another tube, the interior of which is
free from any obstruction. This tube, when excited in the ordinary
manner, shows, as you will observe, the nsual green fluorescence
nearly all over its surface, but especially at the rounded end opposite
the cathode. I suspend this tube over one pole of a powerful electro-
magnet, placed with its axis in line with that of the tube as shown in
Fig. 1. As more and more electric current is passed round the
electro-magnet, and the magnetic field
becomes stronger and stronger, it will
be obs'-rved that the beam of cathode
rays becomes more and more conceu-
trat(3d to a point opposite the pole of
the magnet, until at length when the
magnet is fully excited the whole of
the green fluorescence in the tube has
now entirely died out, and the cathode
stream can be seen as a bluish cone,
the b !se of which is the cathode disc,
and the apex is a very small point
<^xactly over the centre of the magnet
pole. It is not possible to keep the
tube in this condition for more than a
few seconds, as the heat produced on
the glass where the cathode rays are
concentrated is so intense as to quickly
perforate the latter. Indeed, by slowly
moving the tube it is possible to en-
grave on its interior surface any de-
sired figure, the action of the cathode
rays being sufficient to erode the glass.
Fig 2 is a photograph of the globular
end of a tube, upon the interior glass
surface of which, as can be seen, a
square with diagonals has been
roughly engraved by this means.

Whether the action is due directly to the bombardment of the atoms
which form the cathode rays breaking off little pieces of glass as a
volley of minute bullets would do, or whether it is a secondary effect
due to heat, is perhaps uncertain. The result in any case is that
where the concentrated cathode rays impinge upon the glass, the
latter is eroded and visibly roughened.

A concentrated cathode discharge can also be obtained by em-
ploying as cathode a si)herically concave aluminium cup, so arranged
relatively to the glass of the tube that the rays are, given off only from
the hollow side, this being the arrangement now universally used in
tubes for the production of the Eontgen rays. It is a method origi-
VoL. XV. (No. 92. ) 2 Q

PiQ, 1.— Cathode rays fooussod to
a point by means of a magnet.

682

Mr. Alan A. Campbell Swinton

[Fob. 4,

nally introduced by Crookes, more especially for showing the heating
effect of the cathode rays when allowed to impinge upon a piece of
platinum foil, and it is to Herbert Jackson that we owe its application
to the production of the h'ontgen rays.

Here is a tube arranged as
in Fig. 3 with two concave
cathodes opposite one another,
both focussing upon a small
fragment of quicklime. I em-
ploy in this case two cathodes
because I am going to use an
alternating electric current, such
as is supplied from the mains,
but transformed up to some
*iO,000 volts by being passed
through an induction coil.
Each aluminium cup serves in
turn as cathode and anode, and,
as will be observed, when the
current is turned on and con-
ditions are favourable, a very
brilliant aud beautiful light is
produced. This, however, only
lasts for a short time and then
dies out, the strong light re-
curring from time to time at
unequal intervals. This curious
effect, which in result is analo-
gous to the hunting of a badly adjusted arc lamp, requires explanation.
It appears to be due to absorption of the residual gas by the lime
while the latter is white hot, and the giving of it out again at a lower
temperature ; this producing a periodic increase and decrease of the
vacuum, and a consequent decrease and increase of the energy of the
discharge through the tube and of the light. Another curious fact,
and one that supports the bombardment theory of the cathode rays,
is that the rays after having been allowed to fall upon the block of
lime for a little time, are found to bore perlectively straight and very
minute holes in the material. This block, which has been used on
several occasicms, aud has also been turned round a little, was solid
originally, but has now several holes passing right through it, some
of these not being more than about half a millimetre in diameter.
At the edges the material is somewhat bn ken away, but in the
interior the holes have been so accurately eroded by the cathode rays
that they look as though they might have been bored with a small
drill. This shows the great accuiacy with which the cathode rays
cnn be focussed. Again, it is remarkable that though the current is
alternating, and the arrangement of the tube and electrodes perfectly
symmetrical, so that one would expect the heating and luminous effect

Fig. 2. — Figure enuraved on the interior
of a gla^s bulb by cathode rays.

1898.] on Some New Studies in Cathode and Bonfgen Radiations. 583

on both sides of this piece of lime to be the same, the light appears to
be given oflf sometimes only on one side and sometimes only on the
other.

With a tube such as this, excited with an alternating current, it is
easy to produce exceedingly high temperatures confined to a very small

Fig. 3. — Cuthode ray lamp.

area, and it is not at all improbable that it may be eventually found
possible to produce commercially and practically in this way, high
voltage electric lamps of much higher efficiency than the ordinary
incandescent filament lamp, and possibly even rivalling arc lamps. In
both of these latter it is necessary that the incandescent substance

2 Q 2

584 Mr. Alan A. Campbell Swinton [Feb. 4,

Bliould be a fairly good electrical conductor ; whereas in this cathode
ray arrangement there is no such limitation, and consequently there
is a much wider range of available refractory substances. It is also
quite conceivable that in future an electric furnace of this nature may
be found of service in some of the more delicate of chemical investi-
gations where it is necessary to obtain in isolated substances very
high temperatures. Indeed, already Crookes and Moissan have em-
ployed this means for turning into graphite the surface of a diamond.

It is now becoming more and more generally believed that Sir
William Crookes' origiual theory, enunciated some twenty years ago,
as to the nature of these cathode radiations, is at any rate to a large
extent correct. According to this theory the cathode rays consist of
material particles of the residual gas, which being similarly electrified
by contact with the cathode are violently rej^elled by the latter. This
has been the view held for a long time by most En«;lish physicists,
and the chief point of difference now appears to be whether these
material particles are single atoms, single molecules, or larger aggre-
gations of matter.

I have here a model which roughly shows what is supposed to
take place. As you see, there are facing one another t^o plate
electrodes, which I am able to charge positively and negatively
respectively by means of a Wimshurst machine ; between them is
suspended by a silk thread, what for the moment we will assume to
be a single atom. It is in fact a gilded pith ball. As soon as I turn
the handle of the "Wimshurst machine and electrify the electrodes, as
you see, the ball oscillates rapidly from one to the other. If it starts
in contact with the negative electrode it receives from this a negative
charge ; it thereupon is repelled until it strikes the positive electrode,
where it gives up its negative charge and receives a positive one.
Again, owing to mutual repulsion, it is driven across to the negative
electrode, and so on backwards and forwards. U'his is a very simple
and elementary experiment, which I would not have ventured to show
you except that it leads to another which is perhaps of more interest.
If the atoms in a tube were caused to fly backwards and forwards at
equal velocities, as did the pith ball, between anode and cathode, it is
obvious that there would be an anode stream similar in most if not in
all respects to the cathode stream, which does not appear to be the
case. If, however, I now remove the connection betweeu the positive
electrode and the Wimshurst machine, and instead, connect the posi-
tive electrode to earth, leaving the negative electrode connected to the
Wimshurst machine as before, it will be seen that the pith ball flies
with much greater violence and rapidity from cathode to anode than
it does on its return journey from anode to cathode. This is for the
reason that while in the former case we have both the repulsion of the
cathode on the similarly electrified ball and also the attraction of the
anode urging the ball on its path, on the return journey both ball and
anode are at zero potential, and consequently there is the attraction
of the distant cathode only causing the ball to move. Now, if we

1898.] on Some New Studies in Cathode and Bontgen Badiations. 585

consider the condition of affairs inside a focus tube while a discharge
is taking place, this List experiment may help us to understand at
least one possible reason for the atoms not being projected from the
anode at anything like the velocity that they are projected from the
cathode.

Fig. 4 has been prepared to show the probable distribution of posi-
tively and negatively electrified atoms
in a focus tube while the discharge
is taking place. It is larfzely based
upon })revious similar illustrations
due to Crookes, applied to a tube of a
different form. As will be seen, the
greater portion of the bulb is filled
with positively electrified atoms, as
denoted by crosses, while it is only
behind the cathode and in the cathode
stream itself that any nesatively elec-
trified atoms are to be found. That
this is at any rate approximately true
can be proved by means of exploring
poles and in other ways, and it is
curious to note that some of the very
beautiful photographs published by
Lord Armstrong in his recent mono-
graph on 'Electric Movements in Air
and Water' show that in air at ordinary
atmospheric pressure there is a similar
tendency for the positive discharge to
be much more dispersive than the

Fig. 4. — Diaij;ramslio\viiicj probable
distiibution of positiwiy and
nejjjatively charged atoms iu
a focus tube.

ISow assuming that the figure cor-
rectly denotes the condition of the
atoms inside the tube, it is evident
that considering only the contents of

the tube and disregarding everything outside, the anode is very
much in the same condition as the earthed electrode in the pith ball
experiment ; being at the same electrical potential as the great bulk
of its environment. It is very probably for a similar reason that in
a tube of the foj rn illustrated the cathode rays are only given oft' from
the concave side of the cathode, the whole environment of the convex
side being negatively charged, with the result that the atoms there
are in a state of equilibrium.

Whether this explanation is sufiicient or not — and no doubt there
are at work other causes — in any case there is no question that the
velocity of the negative stream is very much greater than the velocity
of the positive stream. That there is something of the nature of a
positive stream, which increases in velocity the higher the exhaustion,
can, however, be' shown experimentally.

686

Mr. Alan A. Campbell Swinton

[Feb. 4,

Fig. 5 is a radiometer tube, exactly similar in principle to those
of Crookes. It consists of an ordinary focus tube, on one side of
which a glass annex has been blown, containing a sliding carrier,
holding half inside a glass cup a small and delicately pivoted wheel
with mica vanes. By the employment of a magnet, which acts on a
piece of iron attached to the sliding carrier inside the tube, I can
move the wheel bodily, cither out into tlie centre of the tube, so that
the cathode stream impinges upjn the vanes, or back into the annex,

Fig. 5.

-Adjustable radiomtter tube for showing both cathode
and anode streams.

when the vanes are quite outside of the cathode line of fire. When
the tube is put into operation in this latter position (that shown in
full lines in the illustration), immediately the current is turned on the
wheel begins slowly to revolve in a direction that indicates a stream
from the anode to the cathode. On the other hand, when the wheel
is moved out into the bulb (in the position indicated in dotted lines),
so that the cathode stream impinges upon the vanes, tlie wheel imme-
diately begins to revolve with great rapidity in the opposite dii ection.

1898.] on Some Neiv Studies in Cathode and Eontgen Badiations. 587

Here, therefore, we have direct experimental evidence that in a focns

tube, while the cathode stream of negatively electrified atoms proceeds

at a great velocity through the centre of the bulb, the anode stream of

positively electrified atoms returns to the cathode at a much lower

velocity round the outside of the cathode stream. Fig. 6 shows

approximately what probably occurs in

a tube of the ordinary focus type, the

direction of the two opposite streams

of positively and negatively charged

atoms being shown by the arrow-heads.
If the discharge within a focus tube

be closely watched during the process

of exhaustion, it will be found to alter

as the vacuum increases. First of all,

at a low vacuum, the cathode rays can

be seen converging in the form of a

cone from the concave cathode to a

focus, and then immediately diverging

again in another cone on the other side

of the focus, as shown on the extreme

left of Fig. 7. It can f ui ther be shown

that the individual rays cross at the

focus. As the exhaustion proceeds,

both convergent and divergent cones,

but especially the latter, become

smaller and smaller, while the thread

that joins them becomes longer and

longer as shown in the succeeding

sections of Fig. 7, till at last, at the

highest vacuum at which the discharge

will pass, the cathode rays, which are

now very nearly invisible, appear to

come off only from a small area at the

centre of the cathode, and not very

ajipreciably to diverge again after once having come together, as

indicate! on the extreme right of the illustration.

Now I have found that if the anti-cathode or anode upon which
the cathode rays impinge is made not of aluminium or of platinum as
usual, but of ordinary electric light carbon, the carbon becomes
luminescent where struck by the rays. Further, if the carbon anti-
cathode be so placed as to intersect either the convergent or divergent
cones of rays, these, instead of producing a uniform luminous patch
upon the carbon, produce a bright ring with a dark interior. This
ring becomes smaller as the vacuum is increased. It develops a
bright spot in the centre as exhaustion proceeds still further, and
finally with a still higher vacuum it closes round the spot until only
the spot itself is left. These effects are shown for each condition of
vacuum in the lower portion of Fig. 7, and I have here a tube that I

Fig. 6. — Diiigram showing prob-
able circ ation of atoms in
a focus lube.

588

Mr. Alan A. Campbell Sivinton

[Feb. 4,

will put into action and show the effect for one degree of vacuum.
As you observe, the luminescence on the carbon is very bright, in fact
the surface appears white hot. It, however, takes the shape of a well
defined hollow ring with a dark interior and a bright spot at tlie
centre, and as I deflect the stream of cathode rays with a magnet, the
ring also moves with no perceptible lag, being at the same time
somewhat deformed, but still retaining its hollow character.

By means of a tube in which the carbon anti-cathode is connected
to the positive terminal by sliding connections, and can be caused to
move along the tube so as to intersect either the convergent or di-

f

t

,v^^^

@

-Appearance and efiect of the cathode rays in a focus tube at four
diffennt degrees of exhaustion.

vergent cones at any desired point, it can be shown that with cathodes
of considerable concavity, both the convergent and divergent cones
of cathode rays are never solid but always more or less hollow in
section.

Now, how can this remarkable effect be explained ? Perhaj^s the
most satisfiictory explanation is that suggested by Professor G. F.
Fitzgerald, which accords with the Crookes theory of cathode rays,
and also with what I have already mentioned as to the anode stream
of positively charged atoms returning to the cathode outside of the
cathode stream 2)assing in the opj^osite direction. If we return to
Fig. G, it is evident that the supply of atoms to the active cathode

1898.] on Some Neiv Studies in Cathode and Uonigen Eadiations. 589

surface is from all ronud the edge of the latter, so that the atoms may
very possibly be all shot off again from the cathode in the form of a
hollow cone before they get further than a certain distance towards
the centre. Further, as the vacuum increases we know from our
experiments with our radiometer tube that the velocity of the positive
stream also increases very considerably, so that under the conditions
of a higher vacuum the atoms approaching the cathode have more
momentum and consequently get nearer to the centre before they
obtain a negative charge and are repelled in the cathode stream, thus
making the stream and the rings smaller in diameter. Of course,
once we start with a hollow convergent cone it is easy to understand
that the divergent cone will also be hollow, seeing that the atoms fiy
more or less rectilinearly crossing one another's paths at the focus.
How to explain the bright spots in the centres of the rings, which
ap (tears to indicate a central negative stream down the axis of the
hollow cones, is more difficult, but possibly the heterogeneous nature

./Q~'

^\i III ill 11 '^ I ki

V

^

m ng

Fig. S.
Apparatus for showiDg the cathude ray spectrum.

of the cathode stream, due very j^robably to the varying veh^cities of
the negatively charged atoms, may bo sufficient to account for this.

Crookes observed many years ago that cathode rays were deflected
by a magnet. Lenard was the first to show that the rays are not
homogeneous, but some are m( re easily deflected than others. Birke-
land went one step further than this, and showed that if a thin cathode
beam was deflected by a suitable magnetic field it was split up into
bundles of rays, and if allowed to fall upon the glass walls of the
tube, it gave fluorescent bands of alternate brightness and darkness,
which he termed the magnetic spectrum.

Fig. 8 represents an ajiparatus for showing this effect. The
cathode rays proceeding from a flat aluminium disc are caused to
])ass through a narrow slit in a piece of platinum which serves as
the anode. After passing through the slit, the rays impinge upon
the bulb, and if otherwise unaffected, produce a luirrow baud of
intense luminescence upon the glass. At each side of the bulb is

690 Mr. Alan A. Campbell Sicinton [Feb. 4,

fixed an electromagnet, producing straight magnetic lines across the
path of the rays. As soon as the magnets are excited the cathode
beam is deflected and split up, and instead of having a single narrow
line of luminescence, we now have many lines with dark intervening
spaces, all in constant movement. An experiment like tiiis cannot be
shown to an audience, but I have prepared photographs which will
make the effect produced clear. Fig. 9 is a photograph taken without
camera or lens, and produced simply by binding a strip of sensitive
photographic film round the bulb of the tube and making a single
discharge by a single break of the contact-breaker of tlie induction
coil. The film being in close contact with the glass is impressed by
tlie luminous bands that the unequally deflected c.ithode rays pro-
duce on the latter, and we have a photographic image of the bands
for a single electrical discharge. Nor is this all. By inserting
between the glass and the photographic film a piece of very thin
black j)aper, so placed as to cover only one-half of tlie spectrum, it is
possible to obtain a photograph of the bands, one half of which is due
to the visible fluorescent luminosity of the glass, and the other half
to the invisible Eontgen rays produced by the impact of the cathode
rays on the glass.

Fig. 10 is such a photogra[)h, and it will be seen that the Uontgen
rays are also given off in bands, which are co-terininons with the
fluorescent bands though photographically fainter tlian the latter.
In the photographs shown, this difference in density between the two
images is lessened by the interposition between the glass and the
film in the case of the luminous portion of a thin sheet of slightly
yellow celluloid. Without this the difference would be so great that
it would not be possible to show both images upon a single film. Of
course, this faintness of the l\ontgen ray bands is only to be expected,
as in tlie photograph of the luminous bands the Eontgen rays are also
present, so that in the one case the photographic image is the result
of both descripti<»ns of radiations, and in the other is caused by only
one. It is worthy of note that in the spectrum image produced by
the Eontgen rays, the greatest photographic effect is always produced
by the least deflected of the cathode ray streams, that is to say, by that
stream which presumably was travelling at the greatest velocity. It
is obvious that the cathode ray atoms which are travelling most
rapidly will be the ones least deflected, just as the faster is the flight
of a bullet the flatter is its trajectory. Hc;re we have a probable
explanation of the existence of the bands which most likely are due
to the atoms of the cathode rays having either from the first different
velocities imparted to them, due to tlie oscillatory character of the
induction coil discharge, or from tlieir gathering into gronps travelling
at different velocities on the well-known principle that occasions the
traflic in the street to form knots of maxima and minima, owing to the
faster vehicles catching up the slower and being impeded by them.

The axial stream in the centre of the hollow cathode ray cones
juay possibly also be due to the same cause.

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1898.] on Some New Studies in Cathode and Rontgen Radiations. 501

In any ca^e tlie photographs that I have shown you prove very
conclusively that those negative atoms which are least deflected by a
magnet are tliose which produce the most active Rontgen rays, and
therefore it follows that the quality of the Rontgen rays is very
largely dependent upon the velocity with which the negative atoms
strike upon the anti-cathode. Quite in harmony with this theory is
an exj^eriment which I will now show you. I have here a Rontgen
ray tube with two cathodes, as shown in Fig. 11. The cathodes are
both in the same tube, and therefore the conditions as regards vacuum
nuist be the same for both. They both focus upon opposite sides of
the same platinum anti-cathode, and they only differ in the fact that

Fig. 11.
Focus tube with two cathodes of differeut diameters.

one is considerably larger than the other. I will now put the tube
into operation, using the larger cathode, and as you see, scarcely any
Rontgen rays are pi'oduced, while what there are do not jienetrate
my hand. I will now alter the connections and use the smaller cathode
instead of the larger one. Now very penetrative Rontgen rays are
generated in abundance, and you can clearly see the shadow of the
bones in my hand on the fluorescent screen.

Here is another tube which is furnished uith four cathod s all of
different sizes and all arranged to focus upon the same anti-cathode,
which can be rotated so as to face the particular cathode in use. This
tube behaves just like the other, and for any given degree of exhau^-tion
gives more penetrative Rontgen rays the smaller the cathode employed,

592 3Ir. Alan A. Campbell Stvinton [Feb. 4,

It is found that tlie smaller the cathode the greater is the E.M.F.
required to cause the electric discharge to pass through the tube, and
probably in consequence of this, and also perhaps because a less number
of atoms can get into tbe vicinity of the cathode at one time, the greater
is in all probability the velocity of the stream of atoms that form the
cathode rays.

The particular material employed for the anti-cathode surface
also materially aifects the production of the Eoutgen rays. This is a
subject that was, I believe, first investigated by Professor Silvanus
Thompson, who found that the best absorbents were the best emitters
of the Rontgen rays — in other words, that the best materials for the
anti-cathode were metals of the higliest atomic weight. If the Eontgen
rays are produced by the sudden removal of velocity from the cathode
ray atoms, or by a sudden change in this velocity by collision with tlie
atoms of the anti-cathode, this is in accordance with what would be
expected, as substances of high atomic w' eight would obviously be the
most efiicient by reason of the greater inertia of tLeir atoms.

I have made numercnis experiments with various metals for the
anti-cathode, and I have here a tube which has a movable anti-cathode
made half of aluminium and half of platinum. By jerking the tube,
-either the platinum or the aluminium i)ortions can be brought opposite
the cathode and put into use, so that under ex^^ctly similar conditions
as regards vacuum, size of cathode and bulb and distance, it is
possible accurately to compare the efficiency of the tw^o substances.
Fig. 12 is a j^hotograph of my wrist taken with the platinum portion
of the anti-cathode, and Fig. 13 one taken with the aluminium portion.
The conditions were otherwise identical, but, as is very obvious, the
result with the platinum is much superior to the other.

The usual method adopted for varying the resistance of a Eontgen
ray tube, and thus modifying the character of the Eontgen rays that
it produces, so as to obtain the exact penetrative quality that is
desired, is by varying the vacuum. Tbe higher the exhaustion the
greater is the resistance to the passage of the discharge, the greater
is the velocity of the cathode rays, and the more penetrative are the
Eontgen rays. This variation of the vacuum is usually effected by
heating the tube, which has the effect of driving out into the interior
molecules of the residual gas condensed or occluded upon the glass.
Apart from this, very possibly the temperature of the contents of tlie
tube and the kinetic energy of the molecules, which is gieater the
higher the temperature, may in itself assist the passage of the dis-
charge.

There are, however, other means of varying the resistance of a
tube and altering the character of the rays that it generat* s which do
not depend upon either the degree of exhaustion or upon the tempera-
ture. One method for effecting this regulation consi>t-! in making the
anti-cathode, which is also the anode, movable, and altering the dis-
tance between it and the cathode ; another in making the cathode
movable and altering its position relative to the glass walls of the tube.

< r

.2 5

^ -3

S-,

be

o

o

s

1898.] on Some New Studies in Cathode and Ronfgen Radiations. 593

In the former case the tube may be constructed as shown in Fig. 14,
in which the anti-cathode is mounted on a sliding stem so that by

Fig. 14.
Adjustable anode tube.

Fig. 15.
Adjustable cathode tube.

594 Mr. Alan A. Campbell Swinton [Feb. 4,

shaking the tube its distance from the cathode can be varied. In
this case the nearer the anti-cathode is placed to the cathode the higher
is the resistance of the tube and the more penetrative are the Eontgen
rays that are generated.

Fig. 15 shows another form of adjustable tube in which the anti-
cathode is stationary, and it is the cathode that is movable. The
cathode is here so mounted upon a sliding stem that it can be moved
in and out of a slightly conical annex blown upon one side of the
glass bulb of the tulie. I will put a tube of this descri2)tion into
operation, beginning with the cathode in the position shown in the
illustration in dotted lines, when it is outside the annex in the bulb,
and let you see tlie effect of gradually moving it backwards into the
annex. We will observe the character of the resulting Eoutgen rays
produced at each position with a fluorescent screen. The tube UFcd
has a small piece of iron attached to the cathode so that we can move
the latter by means of a magnet according to the suggestion of
Dr. Dawson Turner and others.

You observe tliat, to commence with, with the cathode right out in
the bulb, we get E5ntgen rays which can do little more than pene-
trate the black paper backing of tlie screen. My hand throws a dark
shadow on the fluorescent surface, but you can see no bones, as the
rays will not penetrate my hand. I now move the cathode a little
back towards the edge of the annex. The bones are now just visible.
The hand is still very black, but the bones can be seen ; now on
moving the cathode just inside the edge of the annex the bones
become very clear, and when I move it still furtlier into the annex the
rays become very penetrative, and even pass through the bones so that
their structure can be observed.

Figs. 16, 17 and 18 show a series of three photographs of my
hand obtained in this manner. I'hey were all taken with the same
tube under identical conditions as regards vacuum, distance, exjwsure,
photographic plate and development. The position of the cathode
only was altered, and, as will be observed, the results show a marked
increase of penetration the further the catliode was moved towards
and into the glass annex. In the case of Fig. 16 the cathode was
right out in the bulb, in Fig. 18 it was completely in the annex. In
Fig. 17 it was in an intermediate position.

Now we have studied the cause of these effects by means of a tube
in which positions of both anode and cathode can be altered inde-
pendently by a magnetic adjustment. Fig. 19 shows a portion of
the tube, and above it is drawn a curve representing approximately
the difference of potential required to cause a discharge to pass
through the tube with varying positions of the anti-cathode. In the
diagram the abscisssB represent the distance i)etween anti-cathode
(which also formed the anode) and the cathode, divided in tenths of
an inch, while the ordinates represent also in tentlis of an inch the
length of the alternative sparks in air between two brass balls j inch
in diameter. Starting with the anti-cathode in its furthest position

-g

1898.] on Some New Studies in Cathode and Bontgen Badiations. 595

from the cathode, and moving it gradually towards the latter, it will
be observed that at first there is a slight gradual increase in the
length of the alternative spark. Then for the next small movement

Fig.

19. — Dingram showing liow the resistance of a tube is altered
by varying the position of tlie anode.

there is a very sudden increase, and after that again a gradual increase
till we get to the point marked in dotted lines, which denotes the
limit of travel that the anti-cathode was allowed.

Now let us come to Fig. 20, which represents the effect of moving
the cathode in the same tubs, the anti-cathode being stationary in the
position shown. Here, as will be seen, the less the distance between
cathode and anti-cathode the less is the length of the alternative
spark.

This distance in this case doe? not appear, however, to be the
determining factor, as it is more than counterbalanced by the more
important factor of the position of the cathode relatively to the glass
walls of the tube. We have a gradual decrease in the length of the
alternative spark as the cathode is moved a little towards the anti-
cathode, then a further much more rapid decrease as the cathode
emerges from the annex, and a still further slight decrease as it is
moved away from the glass walls out into the bulb.

Now as to the effect upon the Eontgen rays, as it has been before
remarked, the greater the resistance of the tube and the greater the
E.M.F. ncccss.iry to cause a discharge to pass, the greater is the

596

Mr. Alan A. Campbell Swinton

[Feb. 4

velocity of the atoms that form the cathode rays, and the more pene-
trative are the Rontgen rays produced. Further, so far as the moving

Fig. 20. — Diagram showing how the rosislance of a lube is altoved
by varying the position of the cathode.

cathode is concerned, the supply of atoms appears to be of great im-
portance. If penetrative Eontgen rays are desired the access of
atoms to the cathode must be restricted. If only a few atoms can
get to the cathode these are projected at great velocity ; if there is
too ready access the atoms crowd in upon the cathode and the electri-
cal charge of the latter is unable to throw them off with much speed.
It is possible to restrict the supply of atoms to the cathode either by
bringing the latter back into a recess or annex, as in the tube just
shown, or a tube such as is illustrated in Fig. 21, in which both
cathode and anti-cathode are fixed, but in which there is a movable
conical glass shield which can be brought up from behind the cathode
so as to impede the access of the atoms, which, as we have seen, come
in round the edges of the cathode, to any desired extent. This tube
regulates just as did the adjustable cathode tube, and its efficacy goes
a long way to prove that the theory as explained above is substantially
correct.

In order to produce sharply defined Eontgen photographs it is of
course of the utmost importance that the rays should be given off

1898.] on Some New Studies in Cathode and Bontgen Radiations. 597

from a very small area or point.
The sharpness of definitioii
varies considerably with differeut
tubes, and a ready means of
judging as to their quality in
this respect is very useful. I
have here a very pretty arrange-
ment for this purpose which is
the idea of Mr. Mackenzie David-
son. It consists simply of a
square wooden frame over which
are stretched at equal distances
a number of parallel wires. There
are two sets of wires crossing
one another at riglit angles. By
holding this screen near the tube
and examining the shadows cast
by the wires upon a fluorescent
screen at different distances, it is
easy to see whether the definition
of the tube is good or b.id. Here
are three Eontgen photographs
of the wires, all taken at the
same distance but with different
tubes. As will bo observed, they
vary very considerably as regards
distinctness, showing that the
tubes were very unequal in
defanitlon.

Fig. 22 shows a photograph
of the wires taken almost in the
plane of the anti-cathode, the
shadow of which is visible at
the right of the picture. As
will be observed, the shadows
of the wires jiarallel to the
plane of the anti-cathode be-
come less and less distinct the
iurther they are from the Litter,
while the wires that are at right
angles to the anti-cathode plane
are exceedingly indistinct. This
is of course due to the Eontgen
ra3's being given off' from a spot
of considerable area in the par-
ticular tube with which this
photograph was taken, and to
the projection of the active area

Vol. XV. (No. 92.)

Fig. 21.
Tube with adjustable glass shield.

2 R

598

3Ir. Alan A. Camplell Stcinton

[Feb. 4,

becoming more and more of a line when viewed nearer and nearer
towards tbe plane of the anti -cathode.

The best and most accurate way of investigating tbe area of the
anti-cathode from which the I.'ontgen rays proceed is by means of
pin-hole photography. Seeing that the Eontgen rays are not re-
fracted, photography with a lens is of cours-e out of the question, but
with a pill-hole very fairly accurate and distinct images can be
obtained. It is only necessary to place a sheet of lead, pierced by a
p n-h()]e, near the tube, and then to examine the rays coming through
the hole with a fluorescent screen placed some way behind the lead

j

i . i
; ■ : 1

' i
i

. : i

*i

1-
P

Fig. 22.

-Runtgen ray pliotogrsiph of a wire screen, taken almost in the
plane of the auti-catliode, showing astigmatic effect.

sheet, in order to see exactly the size and shape of the active area of
the anti-cathode ; or instead of the screen a photographic plate may bo
employed and the effect re corded.

Fig. 23 shows four pin-hole photographs of the anti-cathode taken
in this way, giving the effect produced with four different distances
between the cathode and anti-cathode. The largest figure is jjroduced
with the greatest distance, and vire versa. It will be observed that
owing to the anti-catln do being placed obliquely to the cathode the
figures are all obli([ue, though somewhat imperfect, conic sections ;
further, that when the distance between cathode and anti-cathode is
great, we have a section of the divergent cone giving a hollow ring
with a central spot, just as was visible with the carbon anti-cathode.
The ring gets smaller and smaller, and finally disappears as the dis-
tance between the electroiles is reduced and the focus api^roaclics the
anti-cathode. It will also be noticed tliat where in the ring porti(m
of the figures the cathode rays strike most normally, that is to say,

1898.] on Some New Studies in Cathode and Rontgen Badiafions. 599

at one of the two points of greatest curvature of each ellipse, the
Hontgon rays are produced more actively than in the remaining
portion, where the cathode rays impinge on the anti-cathode more on
the slant. This is still more marked in Fig. 2i, which shows what
are practically sectiims through the major and minor axes of one of
the images shown in Fig. 28. They were taken similarly to the
others, b:;t with the pin-hole and photographic plate almost in the
j)lane of the antl-cathodc.

By some it is imagined that because the Rontgen rays are so very
penetrating, therefore they are of the nature of an invisible light of
great intensity, which though not affecting the human retina acts
upon photograpliic })lates very powerfully. This is quite erronous,
and as a matter of fact the photographic effect of Kontgen rays is
relatively very feeble. I have investigated this by means of two
photograpliic plates which I have exposed respectively to a very
powerfully excited l^ontgen ray tube, screened by black paper to
remove the visible luminosity, and to the light of a single standard
candle. The Rontgen ray tube was employed at a distance of two
feet, and the candle at a distance of ten feet, so that according to the
law of inverse squares, which holds good for Rontgen rays as for
light, tlie intensities of the two radiations, supposing them to be
equal to start with, would be in the projiortion of 25 to 1. Each
p^ate was exposed in sections for varying lengths of time, five, ten,
fifteen seconds, and so on, each succeeding section being exposed
live seconds longer than the preceding one. By sliding tho two nega-
tives past one another it is possible to compare them very accurately,
and the section exposed to the light of the standard candle for ten
seconds is almost exactly of equal density to the section exposed
to the Rontgen rays for twenty-five seconds. The photographic
power of this particular Rontgen ray tube — and it was a very good one
— was therefoe less than one-sixtieth of that of one standard candle.

With regard to the true nature of the Rontgen rays there have
been many theories. There is the original suggestion of Rontgen
himself, that they may possibly consist of longitudinal waves in the
ether. Others have thought that they were possibly ether streams or
vortices. There is a theory propounded by Tesla and others that
they consist of moving material particles, atoms or corpuscles,
similar to the cathode ruys, which reminds one of Newton's corpus-
cular theory of light. There is the more generally received doctrine
that they are simply exceedingly short transverse ether waves similar
in all respects to the waves of light, only so much shorter than tlie
most ultra-violet waves hitherto known that they pass between the
molecules of matter, and are consequently neither refracted nor easily
absorbed or reflected by any media. Lastly, there is the theory first
suggested to the writer early in 1896 by Professor George Forbes,
and recently independently enunciated and elaborated by Sir George
Stokes, v;liich imagines them to bo frequently but irregularly repeated,
isolated, and indbpendent disturbances or jnilses of the ether, each
pulse being similar 2)erha2)S to a single wave of light, and consisting

2 R 2

600 Mr. Alan A. CampbeU Sivinton [Feb. 4,

of a single transverse wave or ripple, but the pulses following one
another in no regular order, or at any regular frequency as do the
trains of vibration of ordinary light.

Then again, there is the question of the mechanism by means of
which the Routgen rays are produced. They are generated by the
impact of the cathode rays upon the anti-cathode, and it is now
becoming more and more certain that the cithode rays consist of
negatively charge! at)ms travelling at enormous velocity. If we
accept this view, tliere are obvii;usly several methods by which we
may imagine the Eontgen rays being generated by the impact of the
travelling atoms upon the anti-cathode. Each cathode ray at(mi
carries a negative charge, while the anti-cathode is positively charged,
so that when the two come into contact an electrical discharge will
take place between tliem. An electrical oscillation will thus take
l^lace in the atom just as in the brass balls of a Hertz oscillator, and
transverse electro-mnguetic waves will be propagated through the
ether in all available directions. As the electro-static capacity of
the atom must be exceedingly small, the periodicity of oscillation
and the wave frequently will be enormous, while at the same time
the oscillation will probably die out with sufficient rapidity to admit
of only one or two corai)lete periods. At the same time the greater
the difference of potential between atom and anti-cathode at the
moment of impact the greater will be tha amplitude of oscillation,
and the more vigorous and far-reaching the etheric disturbances.

Or we may imagine a more purely mechanical origin for the
Eoutf'en rays. It is believed that tlie velocity of the cathode rays
is enormous, being, as recently measured by J. J. Thomson, over
10,000 kilometres per second, and though Lodge, in his well-known
endeavours to detect a movement of the etlier by dragging a material
body through it, obtained only negative results, of course he could not
i)ossibly obtain any velocity at all comparable to this. Assuming that
at the velocity of the cathode ray atoms these do appreciably drag the
ether with them, there may be some ether effect produced analogous
to the atmospheric effect that is noted as the crack of a whip or a
clap of the hands, as each atom hits the anti-cathode and rebounds.*

Or agiin, it is conceivable that the phenomenon is merely one
of heating, and that the cathode ray atoms are by impact with the
anti-cathode raised to such an enormous temperature that they give
off for a short space of time supor-ultra-violet light. Taking a
velocity for the atoms of 10^ centimetres per secon i, as found by
J. J. Thomson to be the minimum velocity of the cathode rays, and
calculating the temper i^^ure to which a nitrogen atom would be raised
if, when travelling at this speed, it w^ere instantly brought to rest

* Since the above was written, Ihe writer's attention lias been drawn to
Professor J. J. Tliomsou's paper, " A Theoi y of tlie Connection between Cathode
andRoiitgen Rays," in the 'Philosophif-al Magazine 'for February, ia which it is
suggested that Rontgen rays consist of very tliin ami intense tlectro-niagnetic
pulses produced in the etlier by the sudden stoppage by the anti-cathode of the
ekctiifled particles of the cathode rays.

1898.] on SDme^Ncw Studies in CatJwde and Bontyen Badkitlorts. GOL

and the whole of its energy converted into heat in the atom itself,
we have according to the formula

T =

in which 2 J 8 '

T = the rise in lemperatdre in degrees centigrade ;

V = the velocity in centimetres per second ;

J = joules equivalent ;

S = the specific heat of nitrogen, we have the result that the rise
in temperature is no Jess than the stupendous figure of a2)proximately
50,000,000,000 degrees centigrade.

This is upon the probably erroneous assumption that the specific
heat rem.ains constant; but allowing for this, and even allowing for
the mei-est fraction of the energy being converted into heat in the
atom itself, there is obviously an ample margin to admit of a tem-
perature being actually obtained enormously transcendinoj the electiic
arc or anything of which man has any knowledge. Perhaps it may
be objected that it is only when we come to deal with aggregations of
atoms that we can speak of heat, and that a hot atom is a physical
absurdity, ^f, however, we look upon heat as a rhythmic dance of
the atoms, perhaps we may also contemplate the possibility of a single
atom executing a pas seul, and giving })ulpes to the ether at each of
its movements. In any case this difficulty disappears if we imagine
the cathode ray particles each to consist of an nggreg-ition of atoms.

The fact that substances of high atomic weight form the most
efficient anti-cathodes, lends force to the suggestion that the Eontgen
rays are produced in some way by the sudden removal of velocity
from the atoms that form the cathode rays, owing to the collision of
these latter with the comparatively stitionury atoms of wliich the
anti-cathode is composed ; while the efiect observed with the pin-hole
photographs of the anti-cathode, in which, as has been seen, the
cathode rays that strike the anti-cathode most nornjally are the most
eifective in producing lioiitgen rays, is ulso in accordance with this
view. At the same time, the fact that in Eontgen ray photi graphs
of Birkeland's cathode ray spectrum it is always the least deflected
ray that produced tlie greatest photographic eiiVcfc, goes to show that
the higher the velocity of the cathode ray atoms the more efiective
these latter are in generating the Itontgen rays.

In conclusion, I must express my great indebtedness to the very
able assistance of Mr. J. C. M. Stanton and Mr. H. L. Tyson Wolfi".
The latter has blown nearly all the tubes that 1 have been able to
show this evening, while the aid of the former has also been of great
value in a class of experimenting that require s much time and labour.
More than two years have now elapsed since the date of Eontgen's
discovery, and nearly twenty years since the commencement of the
researches of Crookes. Here, as always, we find that " Art is long,
opportunity fleeting, experiment uncertain, judgment difiicult."
Thus wrote the Greek Hippocrates some twenty-three centuries ago,
and time has not impaired the truth of the ancient a])horisni.

[A. A. 0. S.J

602 General Montlily Meeting. [Feb. 7,

GENERAL MONTHLY MEETING,

Monday, February 7, 1898.

Siu James Cuicuton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Enrique Cortes, Esq.

J. S. Fairfax, Esq.

Mrs. S. Fisher,

George Hiimphreys-Davies, Esq.

Oliver ]mray, Esq.

John William Jarvis, E^q.

Ivan Levinstein, Esq.

John Stewart MacArthur, Esq. F.C.S.

The Right Hon. Lord Monk Bretton.

Frederick James Quick, Esq.

Emanuel Ristori, Esq

Charles L. Samson, Esq.

Mrs. R. Lawrence Smith,

Rear-Admiral Arthur Knyvett Wilson, V.C. C.B.

were elected Member» of the Royal Institution.

The following letters were read: —

" 7'o the Treasurer of the lioyal Imtiiutiun uf Great Britain.

"Dear Sir Jawes, '' Jumwrij, 189S.

"As an expression of his attarlmient to tlie Institution with wbicli he wag
so long coiniected, and of liis syiu|iiilhy with it.s objt ct;;, my dear luisliand desired
nie (at sucli lime as .should be mott convene nt to m\.>-e!f) to [vcfcent, in his
name, to tlie lloval Institution a thon>and jxinndg: to be di^posL■d of, as the
Boar<i of Ma- ager^ may sec fif, for the promotion of science.
" I luive now tlie pleasure of iimitliug to you this su)n.

" Yours faitli fully,
(Signed) Loiisa C. Tyndall."

"61 Carlisle Place Man.-ions,

'• Victoria Street, S.W.
"Dear Mns. TvM)ALI>, ''January }7th, IH'JS.

'•1 have to acknowledge your letter, enclosing a crossed clicque of the
value of iKiOO. This gener us donntion to the funds of ti e Koyal Institution,
given by your late husband's ex) res^ed wish, will be notified to the Managers
and to the MembL-rs generally at their next nieetiug, when a formal acknowledg-
ment of their grateful appreciation of it will be communicati d to you. Meanwhile
I trusr, you will allow me to express my own senst^ of the Uiuuitlcence of the gift
and of the simple and toncliing terms in which it has been conveyed.

" The Managers would. I am sure, d( sire to be guided by any wish of yours as
to the applicatitn of the gift, but in the absence of any explicit diiections they
will, I have no doubt, employ it in the piomotion of original scientifio research,
in which your husband's vivid and penetrating intellect delighted to exurcise
itself.

'■Revered as your late husband's memory is, and ever must he, in the Royal
Institution, this j)Osthumous nnirk of Ids solicitude for its welfare will, if possible,
deepen the afl'ectionate esteem in which he is held.

1898.] General Monthly Meeting. 603

"There is not, I regret to say, in the Royal Institution any worthy present-
ment of tlie late Proft ssor Tyndall. Yon liave, I believe, a really good bust of
liim, and I should be glad to know if you would feel disposed to aftord facilities
for having a replica of that made for the Royal Institution.
" With Idml regards,

" Yours very faithfully,
(Signed) James Crichton-Browne."

Moved, seconded, and carried unanimously,

** That the Special Thanks of the Members of the Rojal Institution
of Gicat Britain, in General Meeting assembled, be returned to
Mrs, Tyndall, for her generous Donation of One Thousand Pounds
given in fulfilment of the wish of her husband, the late Professor
Tyndall, for the promotion of Science, which he did so much by his
life-long labours to advance, and in token of his s^mipathy with the
objects of the Royal Institution to which he rendered such signal
service."

The Special Thanks of the Members were returned for tlie
following donations to the Fund for the Promotion of Experimental
Kesearch at Low Temperatures : —

Sir Frederick Abel, Bart £50

Professor Dewar £100

Sir Andrew Noble, K.C.B £100

The Special Thanks of the Members were returned to the Rev.
William J. Packe for his present of an Electiic Lamj) and Fittings.

It was announced from the Chair that the Managers had resolved,
at their Meeting held this day, that the Centenary of the Royal
Institution, which was founded in 1799, would be properly celebrated
next year.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FOR

Tlie Secretary of State for IiuUa — Annual Progress Report of the Arclieeological
Survey Circle, N.W.P. and Oudh, for year ending BOth June, 1897. fol.
Arclixologlcal Survey of India —

Ijists of Antiquarian Remains in the Central Provinces and Berar. By
11. Cousins. 4to. 1897.
Tlie Governor -Gtneral of In'Ua — Geological Survey of India : Records, Yol. XXX.

Part 4. 8vo. 1897.
Tlie Lords <f the Admiralty —
Annah of the Cape Observatory —

Yol. III. The Cape Photugrnphic Durchmusternug for the Equinox, 1895.

By D. Gill and J. C. Kapteyu. Part 1. 4to. 189G.
Vol.' YI. Solar Parallax from Heliometer Observations of Minor Planets.

Vol. 1. 4to. 1897.
Vol. YII. Solar Parallax from Observations of Victoria and Sappho. Vol. II.

4to. 1896.
Cape Meridian Observations, 1861-65. 8vo. 1837.

Appendix to Cape Meridian Observations, 1890-91. (Star Correction Tables
by W. H. Finlay.) 4to. 1895.

604 General Monthly Meeting. [Feb. 7,

Accademia dei Llnce>\ Beale, Homa — Atti, Serie Quinfa: Eendiconti. Classe di

Scienze Morali, \o\. VI. Fasc. 9-12. Clisse di Scienze Fisiche, etc.

2°Seme&tre,Vol.VI. Fnse. 10; P Semestre, Vol. VII. Fasc 1. 8yo. 1897-98.

Atti dell' Accademia Pontificiade' NuoviLiiii ei. AunoL. S<ss. VII''. 4to. 1897.

Agricultural Society of Great Britain, Royal — Juuinil, 3rd iSeries, Vol. VIII.

Part 4. 8vo. 1897.
Amagat, Professor E. H. {the Jr^f/ior)— Rocherches sur I'e'lasticiti de Fair sous de
taibles piessions. 8\o. 1896.
Recherches sur la compressibillte des oraz. 8vo. 1883.
Me'moiie sur Ja eompressibilite' des liquides.
Sur la conipres&ibiliie des fjaz sous de fortes presfcions.

IMe'moire snr la coraprfssibilite' des gaz a dps pressir us elevees. 8vo. 1880.
Reelierches sur Felastieite' des sulides et la eompressibilite du mercure. 8vo.

1891.
Meraoire sur I'e'lasticile' et la dilatabilite des fluides jiisqu'aux tres liautes

pre'ssions. 8vo. 1893.
Sur la pressioQ iuterieure et le viriel des forces inteiieures dans les fluides.

4to. 1895.
Sur la de'term.ination de la densitc' des gaz lique'fie's et de Icurs vnpours saturees.

4to. 1892
Sur la densite des gaz lique'fie's et de leiirs vapenrs satin e'es et sur les con-

slantes du point critique de I'licide carbonique. 4to, 18l»2,
Veiitication d'euseiuble de la loi des etats correspoudants de Van der "VVaals.

4to. 189G.
Sur les relations esprimnnt que les divers coefficients consideres en tliermo-

dynaniique satisfont a la loi des e'tats corrtspoudants. 4to. 1897.
Sur les variations du rapport des chaleurs spe'cifiques des fluides. 4to. 1895-96.
Sur la pression inte'rieuie dans les fluides et la forme de la fonction ^ (p v t) - 0.

41o. 1894.
Notice sur les travaux scimtifiques de E. H. Amagat. 4to. 189G.
American Geogrojihical Siaciety — Bulletin, Vol. XXIX. No. 2. 8vo. 1897.
Asiatic Society of Bengal — Proceedings, 1897, Nos. 5-8. 8vo. 1897.

Journal, Vol. LXVl. Part 1, Nos. 2, 3 and Extra Number; Part 2, Nos. 2, 3.

8vo. 1897.
The Ka^miracabdamrla: a Ka(;niiri Grammar written in the Sanskrit language
by Icvara-Kaula. Edited, with notes and additions, by C. A. Grierson.
Part I. Declension. 8vo. 1897.
AHatic Society, Royal — Journal, Jan. 1898. 8vo.
Astronomical Society, Roycd — Monthly Notices, Vol. LVIII. Nos. 1, 2. 8vo.

1897.
Bankers, Institute o/"— Journal, Vol. XVIII. Part 9; Vol. XIX. Part 1. 8vo.

1897.
Bashforih, The Rev. F. B.D. (the Author)— T&hles of Remaining Velocity, Time
of Flight and Energy of various Projectiles, 1865-70. 8vo. 1891-92.
A Mathematical Treatise cm the Motion of Projectiles. 8vo. 1893.
Batavia Magneticcd and Meteorological Observatory— Oh^ex\a.{\ons, Vol. XIX.
4 to. 1897.
Rainfall in the East Indian Arcliipelago for 1896. 8vo. 1807.
Bauer, L. A. Esq. (the Author) — First Report upon Magnetic Work in Maryland,

including the Histoiy and Objects of Magnetic Snveys. 8vo. 1897.
Birmingham and Midland Institute — Programme for 1897-98. 8vo.
Boston, U.S.A., Public Library — Annual List of Books added to the Library,
1896-97. 8vo. 1898.
Monthly Bulletin of Books added to the labrary, Vol. II. No. 12; Vol. IIL
No. 1. 8vo. 1897.
Bright, C Esq. (the Compiler) — Map of the World's Telegraphic System, 1897.

fol.
British Architects, Royal Institute o/— Journal, 1897-98, No-. 3-6. 8vo.
British Astronomical Association — Journal, Vol. VIII. Nos, 2, 3. 8vo. 1897.

1898.] General Montldij Meeting. 605

Cambridge Philosophical Society — Proceedinizs, Vol. IX. Part 7. 8vo. 1898.

Transactions, Vol. XVI. Part 3. 4to. 1898.
Camera C/m&— Journal for Dec. 1897 and Jan. 1898. 8vo.

Canada, Geological Survey o/— Paleozoic Fossils, Vol. III. Part 3. 8vo, 1897.
Chemical Industry, Society o/— Journal, Vol XVI. Nos. 11, 12. 8vo. 1897.
Chemical Society — Journal for Dec. 1897 and Jan. 1898. 8vo.

Proceedin«,% Nos. 181-187. 8vo. ls97.
Church, Professor A. H. F.E.S. M.i?./.— Register of the Staff and Students of the
Royal Agricultural Colhge, Cirencester, from 1844 to 1897, with Historical
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Civil Engineers, Institution of — Minutes of Proceedings, Vol. CXXX. 8vo.

1897.
Colliery Guardian, Editor of— Map showing lines of Equal Magnetic Declination

for Jan. 1, 1898.
Committee for the Survey of the Memorials of Greater London — Report, May 1897.

fol.
Cooper, F. A. Esq. B.Sc. (the Author)— The Origin of Zymotic Diseases. 8vo.

1897.
Cracovie, Academic des Sciences — Bulletin International, 1897, Nos. 9, 10. 8vo.
Currie & Co. Messrs. Donald (the Pul >l i sh ers) -IWusti-dted Official Handbook of

tlie Cape and South Africa. Edited by J. Noble, hxo. 1893.
Dublin Society, lioyal — Proceedings, New Series, Vol. VIII. Part 5. 8vo. 1897.

Trans.ctions, Vol. V. No. 13; Vol. VI. Nos. 2-13. 4to. 1896-97.
Editors — American Journal of Science for Dec. 1897 and Jan. 1898. 8vo.

Analyst for Dec. 1897 and Jan. l!s98. 8vo.

Anthony's Photographic Bulletin for Dec. 1897 and Jan. 1898. 8vo.

Aeronautical Jrunml for Jan. 1898. 8vo.

Astropliysical Jonrnal for Nov.-Dec. 1897. 8vo.

Atheureum for Dec. 1897 and Jan. 1898. 4to.

Author for Dec. 1897 and Jan. 1898.

Bimetallist for Nov.-Dec. 1897 and Jan. 1898.

Brewers' Journal for Dec. 1897. 8vo.

Chemical News for Dec. 1897 and Jan. 1898. 4 to.

Chemist and Drnggist for Dec. 1897 and Jan. 1898. 8vo.

Education for Dec. 1897 and Jan, 18'.i8. 8vo.

Electrical Engineer for Dec. 1897 and Jan. 1898. fol.

Electrical Engineering for Dec. 1897 and Jan. 1898.

Electrical Review for Dec. 1897 and Jan. 1898. 8vo.

Engineer for Dec. 1897 and Jan. 1898. fol.

Engineering for Dec. 11S97 and .Ian. 1898. fol.

Engineering Magazine for Dec. 1897. 8vo.

Homoeopathie Review for Dec 1897 and Jan. 1898.

Horological Journal for Dec. 1897 and Jan. 1898. 8vo.

Industries ami Iron for Dec. 1897 and Jan. 1898. ful.

Invention for Dec. 1897 and Jan. 1898. 8vo.

Journal of Physical Chemistry for Dec. 1897. 8vo.

Journal of State Medicine for Dec. 1897 and Jan. 1898. 8vo.

Law Journal for Dec. 1897 and Jan. 1898. 8vo.

Machinery Market for Dec. 1897 and Jan. 1898. 8vo.

Nature for Dec. 1897 and Jan. 1898. 4to.

New Church Magazine for Dec. 1897 and Jan. 1898. 8vo.

Nuovo Cimento for Nov. 1897. 8vo.

Physical Review f3r Nov.-Dec 1897. 8vo.

Public Health Engineer for Dec. 1897 and Jan. 189S. 8vo.

Science Siftings for Dec. 1897 and Jan. 1898. 8vo.

Terrestrial Magnetism for Dec. 1897. 8vo.

Travel for Dec. 1897 and Jan. 1898. 8vo.

Tropical Agriculturist for Dec. 1897 and Jan. 1898. 8vo.

Zoophilist for Dec. 1897 and Jan. 18J8. 4to.

606 General Monthhj fleeting. [Feb. 7,

Emigrants' Information 0/??>e — Canada Circular, 1898. 8vo.
Austral asiau Colonies Circular, 1898. Svo.
South Afrioan Colonics Circular, 1898. 8vo.
Florence, Bihloteca Nazionale Cewfm/e— Piollettino, Nos. 28^^-230. Svo. 1897.
Franlihi Instltiite — J ourniil for Dec 1897 and Jan. 1898. 8vo.
GeograiMcal Society, J?o?/aZ— Geographical Journal for Dec. 1897 and Jan. 1898.

"Svo.
Harlem, Sonlete HoUandaise des Sciences — Arcliives Neerlaudaises, Se'rie II.
Tome 1, Livr. 2, 3. 8vo. 1897.
CEuvies completes de Christian Huvgens. Tome YI. Correspondance, 16G6-C0.
4t^). 189.5.
Harvard Callege, Astronomical Ohservafori/ — Fiftj'-seconl Eeport. 8vo. 1897.
Hidor'cil Socif^.ty, Boyal — Transactions, New Scries, Vol. XI. Svo. 1897.

Index i,f ArcliEeological P.ipers published in 189G. Svo. 1897.
Horticultural Society, Boyal — Arrangements for 1898. Svo.

Report, 1897-98. Svo.
Hlinois State Laloratory of Natural History — Bulletin, Vol. V. Part 3. Svo.

1897.
Imperial Jns/i7?t/e— Imperial Institute Journal for Pec. 1897 and Jan. 1898.
Jervis, Chevalier G. — Measures of Time, or Elementary Princip'es of Technical

Chronology of Eastern Nations. By T. B. Jervis. Svo. 1836.
Johns Hopkins Unicersify — Univcrsitv Circulars, Nos. 132, 133. 4to. 1897.
American Journal of Philology, Vol. XVIII. No. 3. Svo. 1897.
American Chemical Journal for Dec. 1897.
Junior Engineers, Institution <f — Record of Transactions, Vol. VI. Svo. 1897.
Le Chatelier, Frof. H. {the Aidhor)— 'Notice sur les travaux scientitiques de H. le
Chatelier. 4to. 1897.
Les piincipes fondamentaux de I'energe'tique et leur application aux pheno-

mencs cldmiquts. Svo. 1^91.
Recherches expe'rimentales et theoriqucs sur les e'quilibres chimiques. Svo.
1888.
Leighton, John, Esq. F.S.A. M.BI. (the Author)—I\\e Unification of London.

Svo. 1895.
Linnean Society — Journal, No 230. Svo. 1897.

London County Council Technical Education Board — Loudon Technical Educa-
tion Gazette for Dec. 1897 and Jan. 1898. Svo.
Madrid, Boyal Academy of Sciences — Memorias, Tomo XVII. Svo. 1897.

Discursos del M. P. ]M. Sa<;asta Svo. 1897.
Manchester Free FuUic Libraries Commi77ee— Forty-fifth Annual Report, 1896-97.

Svo.
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Meteorological Society, i?o?/aZ— Meteorological Record, Nos. ijb, G6. Svo. 1897.
Microscopical Society, Boyal— iowvwA, 1897, Part 6. Svo.
Navy League — Navy League Journal for Dec. 1897 and Jan. 1898. 4to.
New Zealand, Begistrar-General of — The New Zealand Official Ytar-Book for

1897. Svo.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLVII. Part 1. Svo. 1897.
Odontological Society of Great 5r/7am— Transactions, Vol. XXX. Nos. 2, 3. Svo.

1897.
Faris, Societe Francaise de Physique— Bnlletm, Nos. 104-108. Svo. 1897.

Seances, 1897, Ease. 2. Svo.
Fharmaceutical Society of Great iJnVain— Calendar, 1898. Svo.

Journal for Dec. 1897 and Jan. 1898. Svo.
Philadelphia, Academy of Natural Sciences — Proceedings, 1897, Part 2. Svo.

1897.
Photographic Society of Great Britain, Boyal — The Pliotograpliic Journal for

Nov.-Dec. 1897. Svo.
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1898.] General 3IonlJthj Meeting. GOT

Bio de Janeiro, Ohserraforio — Annuario para 1897. 8vo.

Borne, Ministry of FuhiiG IFor/rs —Giurnale del Gcnio Civile, 1897, Fasc. 7. Aucl

Dcsigni. fol.
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Boi/al. Scottish Socieiij qMrts— Transactions, Vol. XIV. Part 3. 8vo. 1897.
Boyal t<ociety of Edinhitrqh — Proceedings, Vol. XXI. No. 6. 8vo. 189G-97.

Transactions, Vol. XX'XVIH Part 1. 4to. 1897.
Boyal Society of London — Piillosophical Tran.sactions,Vol. CLXXXIX.B. No. 151 ;
Vol. CXO. A. Nos. 207, 208. 4to. 1897.
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Sanitary Inditute—Jonrn&l for Jau. 1898. 8vo.
Silicon Society of Sciences, Uoyal —
Mathematisch-riiysisrhe Classe —

Berichte, 1897, No. 4. 8vo. 1897.
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Berichte, 1897, No. 1. 8vo. 1897.
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Smith, Basil Wood, Esq. F.B.A.S. M.B.L— Chinese Bescarclies. By A. Wylie.

8vo. (Shanghai) 1897.
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1897.
S'jciety of Antiquaries — Arcliajologia, Vol. 1-V. Part 2. 4fo. 1897.
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Ston'-y, G. Johnstone, Esq. M.B I. F.B.S. {the Author)— 0( Atmospheres upon

Planets and Satellites. (2 Cf)pies.) 4to. 1897.
St. Pidersbourg, Academie Impe'i iaie des Sciences — Bulletin, Tome \, N- s. 3 5:
Tome Vl" Nos. 4, 5; Tome Vil. No. 1. 8vo. 189G-97.
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Spettroscopisti Italiani, Vol. XXVI. Disp. 10-12. 4to. 1897.
Thompson, Professor S. P. F.B S. M.B.I {the ^M///or)— Presidential A Idress
delivered at Inaugural Meeting of Ptontgen Society, Nov. 1897. 8vo. 1897.
United Serrice histitalon, Boyal — Journal for Jan. 1898. 8vo.
I'nited Stcdes Department (f Agri<nlture — Experiment Station Kecord, Vol. VIII.

No. 12; Vol IX. No. 3. 8vo. 1897.
United States Geologiccd /S'^rw?/— Se-venteenth Annual Report, 1895-96, Parts 1, 2.
4to. 189ij.
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(U.S.G S. Bull. No. 143.)
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LXXXII. Nos. 2, 3. 8vo. 1897-98.
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Heft 9, 10 ; 1898, Heft 1. 4to.
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1897.
Yale University Ohiervatory — Report, 1896-97. 8vo.

608 Dr. J. H. Gladdone [Feb. 11.

WEEKLY EVENING MEETING,

Friday, February 11, 1898.

Siu EiAVAiiD Frankland, K.C.B. D.C.L. LL.D. F.R.S.

Vice-PresideDt, in the Cliair.

J. H. Gladstone, Esq. D.Sj. F.R.S. M.E.L

The Metals used hij the Great Xations of Antiquitij.

At the beginning of this century little was known of the great
nations of antiquity, except through the classic poets and historians,
and the sacred writings of the Hebrew people. Since then onr know-
ledge has been enormously increased by the labours of scholars and
explorers; the ruins of ancient cities have been exhumed, and the
contemporary literature of Egypt and Assyria, inscribed on papyri
or tablets of clay, and painted or carved on the walls of temples,
palaces and tombs, has been deciphered. AVhat is in some respects
still more important is, that objects found in these ruins have thrown
great light upon the daily life of the people and their ornamental
and useful arts. One of the departments of this inquiry concerns the
metals used by the different nations, and at the different epochs of
their history ; and it is to this department that my attention will be
confined this evening. The difficulty I experience is the vast amount
of material ; and I cannot attempt anything more than a general view
of the subject and some of the most salient points.

The area over which the inquiry extends is that of the lands
bordering on the eastern half of the Mediterranean, and stretching
eastwards to the Persian Gulf. The time, so far as Egypt is con-
cerned, includes the whole period from the first Pharaoh, Mencs, to
the conquest of the country by Alexander the Great ; ranging from
about B.C. 4400 to b.c. 332. The chronology employed throughout is
that of Dr. Wallis Budge, of the British Museum, who has adopted in
the main that of Brugsch Bey. This period of 4000 years appears to
me of reasonable length, and errs, if anything, on the side of modera-
tion. Our kuowledge of the other nations docs not extend to any-
thing like so remote a time.

Egypt.

If we take as our starting-point Seueferu's triumphal tablet in
Wady Maghara, in the Sinaitic peninsula, we see the king flourishing
his battle-axe over the head of his enemy. This symbolises the
conquest of the copper and turquoise mines of that region, and implies
of course their previous oxisteucc as a source of wealth. In the

1808.] on the Metals used by the Great Nations of Antiquity. 609

hieroglyphic inscription above his head there is not only the king's
name spelt phonetically, but in the royal titles are seen two ideographs
which bear upon our subject. One is the necklace or ornamental

collar f^wfl^"!, which is the well-known symbol for gold ; and the other
an axe , the head of which resembles that of a copper rather than
of a stone weapon. These titles have no reference to the metals
themselves, but mean "^^^ f>rm<<'\ " Gulden Horus," and | Ij " Benefi-
cent Divinity." Before such symbols could be used to express
abstract idea«, they must have been well known in their c.^.ucrete
form. The date assigned to Seiieferu is B.C. 3750 ; but the dis-
coveries of the past year have put in our possession the actual metals
themselves, of a nmch greater antiquity. M. de Morgan, late Director
(jeneral of Antiquities in Egypt, has explored an enormous royal
tomb at Nagada, the centre chamber of which contained the mummy
of the Pharaoh, with the cartouche of King Menes, the reputed first
King of Kgypt. If it be really his tomb, the probable date will be
B.C. 44 )0. What is interesting to us is that in two of the chambers,
among a multitude of articles made of ivory, quartz, porphyry, wood,
alabaster, tortoiseshell, mother-of-pearl, obsidian, earthenware, corne-
lian, glass and cloth, there were found some small pieces of metal,
viz. two or three morsels of gold, and a long bead of that metal of a
somewhat crescent form, together with some art cles of copper — a kind
of button, a bead, aud some fine wire.* The button was analysed by
M. Berthelot, the well-known French chemist and politician, to whom
we are indebted for the examination of a very large number of ancient
metallic objects ; he states that it is nearly pure copper, without
arsenic or any other metal in notable proportion.]"

Thcpe are the oldest metallic obj( cts in the world to which we
can assign a probable date. But Prof. Flinders Petrie had discovered
three years ago, also at Nagada, a great number of objects of the same
character, and among them a few small copper implements. Some
filings from a dagger, a celt, and a little harpoon were analysed by
me, and found to consist of pract'cally pure copper, without any trace
of tin. The remains of these filings are in the little bottles on the
table. The age of these tools must be com| arable with that of the
royal tomb, and may possibly be even older.

Of about the same period, and perhaps even earlier, are a number
of tombs at and near Abydos, which have been explored by M.
Amelineau, bearing the names of kings unknown to history, accom-
panied by hieroglyphics of archaic form. J In these have been found

* See ' Ethnographie Prehistorique et Tombeau royal de Negadah,' par
J. de Morgan .• Pai-i:^, 1897; pp. 162-3 and 19o-8, in wliich these articles are
derMTibcd and drawn. f Annales Ch. Pli. Avrd, 1895.

t Sec ' L'Age de la Pierre et les Mc'taux,' par J. de Morgan ; Paris, 1896;
cliaj). viii.

610 Dr. J. H. Gladstone [Feb. 11,

larger quantities of copper utensils, viz. pots, hatchets, needles, chisels,
&c., which M. Berthelot also fiucls to be nearly pure metal, but some
contain a little arsenic. It would appear, therefore, that the Egyp-
tians, at the very beginning of the historic period, were acquainted
with the use of gold and copper.* Let us follow the history of these
two metals, beginning with g<jld, which, as it is generally found native,
was probably the first known to man.

According to a letter just received by me from M. Berthelot, all
or nearly all the ancient gold that he has examined contains more or
less silver. This pale coloured gold is sometimes termed electriim,
and was found in great quantity in Asia Minor, where the Pactolus
and other streams " rolled down their golden sands." Gold is fre-
quently represented in the Egyptian sculptures and pictures ; for
instance, in the very interesting scenes of social life at Beni Hassan,
circa B.C. 2100. illustrations of which I now throw upon the screen,
we see the goldsmiths making jewellery, weighing out the metal,
melting it in their little furnaces with the aid of blow- pipe and
pincers, washing it, and working it into the proper forms. In the
picture of a bazaar at Thebes we find a lady bargaining for a neck-
let ; and in another picture we see the weighing of thick rings of
gold and of silver, which were used as articles of exchange. I wish
I could show you the exquisite gold jewellery, inlaid with gems, found
in the tombs of four princesses buried at Dahshur, about B.r. 2850,
and wliich is now exhibited in the museum of Gizeh ; but I can throw
upon the screen the photograj^h of the beautiful enamelled gold neck-
lace of Queen Aliliotpu, b.c. 1700, f The great kings Seti I. and
Rameses II., b c. 1300, worked extensive gold mines in Nubia, which
yielded g(dd free from silver.

To return to the history of copper. In the inscriptions we cannot
distinguish between copper and its various alloys, for th(y are all
exj)ressed by the general teim cJievit, and the symbol of the battle-axe
blade. But if we can get the substance itself and analyse it, we
know what we are dealing with. Many s})ecimens of copper imple-
ments, dating from the fourth to the sixth dynasty, say from b.o. 3750
to 3100, have been examined. '1 hey consist of almost pure copper.
One of the earliest, analysed by me, was a piece of a vessel liom
El Kab, which contained 98 per cent, of copper, the remaining 2 per
cent, being made up of bismuth, arsenic, lead, iron, sulphur and
oxygen, evidently the impurities r\ the original ore.

It was evidently very important for the E^^yptians to harden the
copper as much as jjossible ; and this might be efiectcd in several

* Since Ihe lecture whs delivered the Egypt Exploration Fund has issued a
memoir, under the title of ' Desha^heh,' from which it appc ars that in the \evy
ancient tombs at that place there were found a few gold beads and copper objects,
r.iid a j)i(-ture of an artificer weighing a copper bowl.

t For drawings see ' The Struggle cf the Nations,' by G. Ma&pero, pp. 3
and 97.

1808.] on the Metals used hij the Great Nations of Antiquity. 611

ways: (1) by hammering, (2) by the admixture of arsenic, (3) by
the admixture of tin, (4) by the admixture of zinc, (5) by the
presence of a certain amount of oxygen in the form of cuprous oxide.
As to arsenic, some of the oldest copper implements contain a notable
quantity. Dr. Percy found 2 "29 per cent, in a knife which was dug
up some distance below a statue of Rameircs II. ; and I found 3*9 per
cent, in a hatchet from Kahun, dating back to B.C. 2300, It is said,
however, that the addition of 0*5 per cent, of arsenic is sufficient to
produce a hardening effect; and many specimens of ancient copper
implements contain this amount, though the proportion of arsenic in
copper ores themselves rarely exceeds 0 * 1 per cent.

As to the admixture of tin. It is well known that bronze, the alloy
of cojDper and tin, is stronger than pure copper. The extent of this
depends upon the proporthjn of the two metals, and j)robably on other
circumstances. The oldest supposed occurrence of an admixture of
tin, is in a bronze rod, found by Flinders Petrie in a mastaba at
Medum, probably of the fourtli dynasty, which I found to contain
9*1 per cent, of tin.* It seemed so improbable that tin should be
employed at so remote a period, and that in sufficient quantity to
make what we call gun-metal, that I was suspicious of its genuineness,
notwithstanding the very circumstantial account of its discovery ;
but M. Berthelot has since found in a ring from a tomb at Dahshur,
believed to be not much later than the third dynasty, 8*2 per cent,
of tin; and in a vase of the sixth dynasty, 5*68 per cent, of tin. "j"
These seem to restore the credit of Dr. Petrie's specimen. At a later
period weak bronzes become common. Thus, at Kahun, tools found
in a carpenter's basket by Prof. Petrie contained varying amounts of
tin from 0-5 to 10 '0 per cent.; 6 or 7 per cent, of tin was subse-
quently common. Bronze implements abound in Egyj^t. I am able
not only to throw upon the screen representations of arrow- and
spear-heads and battle-axes, but, through the kindness of Sir John
Evans, to show a beautiful large spear-head with an inscription of
King Kames (b.c. 1750) down the blade. I am also indebted to
Prof. Hinders Petrie and Dr. Walker for this collection of imple-
ments of the twelfth dynasty from Illahun, including a fine mirror
with ivory handle, necklets, and a bronze casting for a knife, which
was never finished ; also many objects of the eighteenth dynasty, or
thereabouts, such as a sword, dagger and axe, together with mirrors,
bracelets, earrings and pendants, and a steelyard. My own collection
contains specimens of what are believed to be razors of different types,
and small statuettes of Osiris, Isis and others.

As to the admixture of zinc. There does not seem to be any
specimen of brass, properly so called, found in Egypt within the
period of our inquiry ; but various attempts are known to have been

* Particulars of this and other imaly&es may be foimd in 'Proceedings of the
Society of Biblical Archfeology, March 1^90, March 1892, and March 1891.
t Fcuilles a Dahchour e:i 189 1, pp. loG-9.

612 Dr. J. H. Gladstone [Feb. 11,

made to imitate gold, of which aurochalcnm is an instance, and that
may have been yellow brass.

As to oxygen. It is generally supposed to exist in copper in the
form of the red cuprous oxide ; and most of the copper, and many of
the bronze, implements have a covering of this substance. This is
caused by the gradual formation of an oxychloride of copper through
the action of alkaline chlorides in the soil, aided by the air and
moisture. Berthelot has worked out the chemistry of this substance
very fully, and shows how when once formed it gradually works its
way into the solid metal, transforming it into the suboxide, and
frequently disintegrutiug it. Some good specimens of little bronze
images suffering this disintegration are exhibited by Mr. Joseph Offord.
Two at least of the copper adzes on the table consist to the extent of
30 or more per cent, of oxide of copper; they are exceedingly hard,
and it becomes a question whether the formation of the oxide is due
to the slow chemical change, or whether it was purposely produced
in the manufacture in order to harden them. The effect of different
proportions of oxygen on the tenacity of copper is known to be very
various, and certainly deserves further investigation.

It is difficult, or rather impossible, to express in definite figures
the advantage gained by the ancient Egyptian metallurgists through
this alloying of the copper. Arsenic, tin or zinc may and do affect
the hardness, or the tenacity, or the elasticity, in different ways, and
also according to the proportion of the metal united with the copper.
Thus, there are several very different kinds of alloys of copper and
tin, though they are all included under the name of bronze ; more-
over, a piece of copper which has been exposed to a considerable
stress, is permanently altered in its properties. Again, in any table
of numerical values, it should be taken into account whether the
copper with which the alloys are compared had been made as pure
as possible, or contained a normal amount of oxygen.* We must
rest contented with the knowledge that copper can be rendered
stronger and more serviceable by these means, and that the ancient
artificers were acquainted with the fact.

Alter the extensive use of copper and bronze in ancient Egypt,
other metals were gradually employed. Silvtr, as distinct from
electrum, seems to have been little used, except for ornamental
purposes.! The diadem of one of the kings named Antef (b.c. about

* For tabulated results of experimf-Vits bearing on these points, see * The
Testing of Materials of Constructiuu,' by Prof. Cawthorne IJnwin ; and the
second Report to the Alloys Reseai eh Corandtteo of the Institution of Mechanical
Engineers, by Prof. Roberts-Austen, witii the discussion thereon. —Proc. Inst.
Mi'ch. Eng. April 1S98.

t In tlie translation of 'The Book of the Dead,' by Dr. Wallis Budge,
vol. iii. published since the lecture, it appears that in one of tlie oldtst chapters,
said to have been found by Herutataf, about B.C. 3600, there is a formulary to
be said over a scarab of greenstone encircled with a band of refined copper, and
having a ring of bilver.

1898.] 071 the Metals used h)j the Great Nations of Antiquity. 613

2700), and that of the Princess Nor.bhotep (b.c. 2400), were made of
silver and gold. Silver also occurs among the beautiful jewellery of
the princesses buried at Dahshur, and that of Queen Ahhotpu. But
when the intercourse between Egjpt and the neighbouring nations of
Asia was better established, silver became much more common ; thus
we find it frequently mentioned in the Great Harris papyrus,
(B.C. 1200), in which the King IJameses III. describes his magnificent
presents to the temples and priesthood of Egypt.* The metal lead
also occurs frequently in the same lists, and was used, as elsewhere,
for mixing with copper and tin in the formation of the easily fusilile
bronze used for statuary.

Tin ];as a very interesting history. We have funnel it used in
combination with copper as far back as perhaps B.C. 3100, and
enormous quantities of it must have been afterwards em}doyecl. It is
still a question whether in the first instance some stanniferous copper
ore was used, or whether the Egyptians found that the addition of
a certain black mineral was advantageous for hardening their copper,
or whether from early days they reduced the metal from its ore
and added it to the copper in the furnace. That, at any rate, they
were afterwards acquainted with the metal itself, is clear from the
discovery by Flinders Petrie of a small ring at Gurob (b.c. 1450),
which, on examination, I found to be of tin, im^^erfectly reduced from
its ore. Perthelot has also analysed what was essentially a tin ring,
though alloyed with copper, dating about a century later ; and Prof.
Church describes a scarab of the same metal, which was found on the
breast of a mummy of about the seventh century b.c. This metal also
appears more than once among the rich gifts catalogued on the
papyrus of Rameses III., if " tehi'' is to be so translated.

Although kohl, the sulphide of antimony, was used for blackening
the eyebrows from a very early period, I am not aware of any metallic
antimony in Egypt of older date than some beads found by Prof. Petrie
at lllahun in a tomb of about 800 B.C. They proved to be fuirly
pure metal. It is curious that the art of preparing this metal was
after waids lost, and only rediscovered in the fifteenth century of
our era.

The period of the first use of iron in Egypt is at present a matter
of great controversy. Some contend for its use even in the mytho-
logical period, while others would bring it as late as 800 or 600 b.c.
There exist the oxidised remains of some wedges of iron intended to
keep erect the obelisks of Rameses II. at Tanis, which is near the
border of Palestine ; but there is no positive proof that they were
placed there during his reign. I have little doubt, however, that
the Black Baa, mentioned several times in the Harris papyrus, b.c.
1200, is the same as the /ieXas (nSrjpo^ of Ilesiod : i.e. iron. In the
long account which King Piankhi gives of his invasion of Egypt from
the Upper Nile, he mentions iron more than once among the presents

* ' Epcords of the Past,' vols. vi. and viii.
Vol. XV. (No. 02.) 2 s

(j]4. Dr. J. n. Gladstone [Feb. 11,

made to him by the minor chieftains of the time in token of their
submission, indicating that at this period, B.C. 700, it was still not
very common.

Assyria.

In the country lying between or near the Euphrates and the
Tigris we have some antiquities dating, perhaps, as far back as any
in Egypt. We have also a great amount of Accadian and Assyrian
historical and other literature on tablets and cylinders of clay, and on
the walls of the great palaces ard temples. As in the case of Egypt,
the discoveries of the remotest age are those which have been most
recently published. Dr. Peters has just given us the records of the
explorations of the American Oriental Society at Nippur, and describes
the successive layers of the great temple of Bel.* These appear to
indicate the absence of metal in very remote periods. The oldest
specimens are those recently found by M. de Sarzec at Tello (Lagash)
in Southern Chaldaea. They consist of some votive statuettes, and a
colossal spear, an adze and curved hatchet — all of copper without tin,
according to M. Berthelot's analysis. A small vase of antimony and
a large one of silver have also been found. The period of these is
supposed to be some considerable time anterior to B.C. 2500. At Tel
el 8ifr, in the same neighbourhood, Mr. Loftus discovered a large
copper factory, in which were caldrons, vases, hammers, hatchets,
links of chain, ingots, and a great weight of copper dross, together
with a piece of lead. The date of these is believed to be about B.C.
1500. At Nippur the American explorers found at a higher level, in
the temple of Bel, what they term a jewellei-'s shoj), which consisted
of a box full of jewellery, mainly precious stones, but also containing
some gold and copper nails ; these apparently date from abmit B.C.
1300. In Babylonian graves, and oth{;r places of about the same
period, there have been found objects made of copper and iron and
silver wire ; but the use of metals seems much more restricted in
these great alluvial plains than in contemporary Egypt. Iron,
however, was perhaps an exception. According to Messrs. Perrot
and Chipiez, excavations at Warka seem to prove that the Chaldaeans
made use of iron sooner than the Egyptians ; in any case, it was
manufactured and employed in far greater quantities in Mesopotamia
than in the Nile Valley ; in fact, at Khorsabad M. Place is said to
have found hooks and grappling irons, fastened by heavy rings to
cha'n cables, picks, mattocks, hammers, ploughshares, &c., in all about
157 tons weijfht. Mr. Layard also found at Nimroud a large quantity
of scale armour of iron in a very decomposed state, but exactly
resembling what is represented in the sculptures of warriors. Of this
he collected two or three basketfuls.

Coming down to the period of the great Babylonian Empire, we
find very large treasures of the precious metals changing hands

* ' Nipimr,' by Dr. Peters, Philaflelphia.

1898.] 071 the Metals used hy the Great Nations of Antiquity. 615

during their sanguinary wars. Thus, on the black obelisk of Shal-
maneser II., in the British Museum, we have depicted the embassies
fi'om different nations bringing their tribute to the feet of the king.
The second of these has an inscription reading : " The tribute of Jehu,
sou of Omri ; silver, gold, bowls of gold, vessels of gold, goblets of
gold, pitchers of gold, lead, sceptres for the king's hand, and staves ;
1 received." The gates of his palace at Balawat, now at the British
Museum, were of stout timber strengthened with bands of bronze, and
the Trustees kindly gave me a small piece of the metal for analysis ;
it yielded about 11 per cent, of tin. The grandson of this king,
Rimraon Narari III., probably B.C. 797, took Damascus; and the spoil,
according to the inscriptions, comprised 2300 talents of silver, 20 of
gold, 3000 of copper, 5000 of iron, together with large quantities of
ivory, &c.

Lenormant gives two verses of a magical hymn to the god Fire,
which exist both in Accadian and Assyrian ; they run — " Cojiper, tin
their mixer thou art ; gold, silver, their purifier thou art."

Palestine.

Between the great territories of Egypt and Assyria lies a narrow
strip of country, small in extent, but very important in the history of
civilisation, commerce and religion. During the period of which we
are speaking it was occuj^ied by a succession of different nations. It
formed part of the possession of the great Hittite people. We cannot
read their inscriptions, and we know little of their history. We have,
however, bronze and silver seals that are supposed to belong to them,
and curious bronze figures. They seem to have had abundance of
silver, probably from the mines of Bulgardagh in Lycaonia. We read
of Abraham purchasing a piece of land from Ephron the Hittite for
which he weighed out " four hundred shekels of silver current money
with the merchant." He was, in fact, rich in silver and gold, and
among the presents given to Rebekah were jewels of silver and jewels
of gold.

The first notice of metals in Palestine to which we can give an
approximate date is in connection with the invasion of that land, and
other countries further to the eastward, by the great Egyptian King
Thothmes III.* He led his army through the plai nof Esdraelon,
and gained a victory at Megiddo, and amongst the spoil were chariots
inlaid with gold, chariots and dishes of silver, copper, lead, and what
was apparently iron ore. This took place about B.C. 1600. The
original of the long treaty of peace and amity between Katesir, King
of the Hittites, and Eameses II. is said to have been engraved on
tablets of silver.

When the children of Israel left Egypt they were, of course,

* * Eecords of tlic Past,' vol. ii.

2 S 2

616 Br. J. H. Gladstone [Feb. 11,

acquainted with the metals used in that country. They borrowed
the jewels of silver and gold of their oppressors ; and of these the
golden calf was afterwards made. We read, too, of the " brazen
serpent,' * and of elaborate directions for the use of silver, gold and
biass in the construction of the Tabernacle. Lead is mentioned
once, but iron seems to have been unknown to them, the word never
occurring in the Book of Exodus ; and though it is occasionally
mentioned in the later Books of Numbers, Deuteronomy and Joshua,
it is always with reference, not to the Israelites, but to the nations
they encountered. Thus we read of the Midianites having gold,
silver, copper, iron, tin and lead, which were to be purified by pass-
ing through the fire ; of the King of Bashan, a remnant of the
Rephaim, who had the rare luxury of an iron bedstead, which was
kept afterwards as a curiosity at Rabbah ; and of the spoil of the
Amorite city of Jericho, comprising gold, silver, copper and iron.
Later on the Canaanites wei e formidable with their " nine hundred
chariots of iron ; " and later still the Philistines, whose champion,
(j'oliath of Giith, was cla I in armour of bronze, and bore a spear with
a heavy head of iron. Among the materials collected by David in
rich abundance for the building of the Temple were gold, silver,
bronze and iron ; but the best artificers in metals were furnished by
Hiram of Tyre, at the request of Solomon. During the reign of the
latter there was an immense accumulation of these j^recious metals in
Jerusalem. The comparative value of the different materials is
indicated by the words of the j^rophet in describing the Zion of the
future, "For biMSS 1 will bring gold, and for iron 1 will bring silver,
find for wood brass, and for stones iron" (Isaiah Ix. 17). Another
prophet (Jeremiah vi. 29, 30) uses the simile of the refining of silver
by the process of cupellation.

1 he great mound of Tel el Hesy affords a very perfect example
of the debris of town upon town during many centuries ; and of the
lis;lit that these mounds throw upon the progress of civilisation.
When Joshua, after the decisive victory of Bethhoron, led his troops
to the plain in the south-west corner of Palestine, he besieged and
took Lachish, a city of the Araorites. It then became an important
stronghold of the Israelites : its vicissitudes are frequently mentioned
at various dates of the sacred history, as well as on the Tel el Amarna
tablets. The mound has lately been explored by Messrs. Petrie and
Bliss ; and in the remainsof the Amorite city (perhaps b.c. 1500 ) there
are large rough weapons of war, made of cop|»er without admixture
of tin ; above this, dating perhaps from 1250 to 800, appear bronze
tools, with an occasional piece of silver or lead, but the bronze
gradually becomes scarcer, its place being taken by iron, till at the

* The word " brass," at the time of the transLition of our Bible was used
indiscriminately for copper or anj' of its alloys ; so was also the correspondino^
Hebrew term. In the Old Testament it never refers to the alloy of zinc, to
whifh the term brass is now conliiied.

1898.] on the Metals used by the Great Nations of Ant I quit i/. 617

top of the mound there is little else than that metal. The Palestine
Exploration Fund has kindly lent me specimens of these finds for
exhibition. About b.c. 700, Lachish was the headquarters of Sen-
nacherib during his invasion of Palestine. From it he sent his
messengers to Hezekiah, and at the same town he received the peace
offering of the Jewish king, 300 talents of silver and 30 talents of
gold, to raise which he had to despoil his palace and the Temple.
In Sennacherib's own version of the transaction the silver is given
as 800 talents, and the gold 30. Lachish was finally deserted about
400 B.C. -

Greece.

Wo know little of the very early history of Greece, for the most
ancient monuments bear no inscriptions, and literature did not com-
mence till the time of the Homeric poems. In these, and in Hesiod,
there are many graphic descriptions of the habits and arts of the
heroic period, including the use of metals ; and many of the towns
described in them have recently been explored with great success,
and have y'elded up the very materials about which they sang.

Piobably the earliest find has been in the volcanic island of
Santorin, where, uud. r beds of pozzolana. which are supposed to date
about 2000 b.c , have been found two little rings of beaten gold and
a saw of pure copper. In the Ashmolean Museum there are a very
ancient silver ball and beads of the same metal rolled from the flat,
also a spear-head of copper. These were obtained from Amorgos.
In Antiparos there have also been found very ancient objects of silver
mixed with copper.

Passing to the mainland, the towns of the Peloponnesus and the
momid of Hissarlik, the supposed Troy, have been explored by,
Dr. Si hliemann, Dr. Tsountas, and Dr. Dorpfeld ; and they reveal
what is termed the MycenEean period, which figures so largely in the
poems of Homer and Hesiod. In these the precious metals, gold and
silver, are constantly mentioned, together with xakKo<i. generally
translated br.iss. Thus, in the description of Achilles' shield, we are
introduced to Hephaistos at his great forge on Etna, heating the bars
of silver, or brass, or tin, or gold, and then hammering them on the
anvil, so forming the designs which represent so beautifully tlie
various scenes of j eace and war. After having fashioned the shiekl,
he is represented as forging for the warrior a cuirass of copper,
greaves of tin, and a helmet with a golden crest.

Homer frequently mentions iron, but generally gives it the epithet
*' worked with toil," and treats it as a rare and costly metal. Thus
a huge iron discus was given as a valuable prize to the hero who
could throw it the farthest in the athletic games at the funeral of
Patroclus.

Mr. W. E. Gladstone, who has long turned the great powers of
his mind from time to time to Homeric studies, wrote me lust summer :
" The poems of Homer showed mc, I think, forty years ago that tijcy

G18 Dr. J. H. Gladdone [Feb. 11,

represented in the main a copper age." The reasons he assigns in
his letter, as well as in his published works, are fairly conclusive, and
the recent exploratiocs, and the analyses of Dr. Percy, Prof. Roberts-
Austen, and others, have shown that in the early period of the
Mycenaean age copper without tin was employed for numberless pur-
poses ; but as time advanced, bronze came into use. At Hissarlik,
in the lowest and second city, have been found a gilded knife-blade,
needles and pins, of practically pure copper ; while in the third and
sixth cities occur battle-axes of copper containing 3 to 8 per cent, of
tin. In the very old town of Tiryns, the palace apparently had its
walls covered witli sheets of cojDper ; much lead was also found there.
At Mycenai, the Achaian capital* the metals in use were gold, silver,
copper, bronze ai^d lead ; copper jugs and caldrons are common,
and great leaden jars for storiug grain ; also elegant bronze tools
and cutlery ; mirrors, razors and swords. In the tombs the bodies
are laden with jewels, largely ornaments of gold, with a much smaller
amount of silver.

Some of these objects illustrate the poems of the time ; thus, in
the Odyssey we find Nestor makinoj a vow to AthenaR : " So the heifer
came from the field ; . . . the smith came holding in his hands his
tools, the means of his craft, anvil and hammer, and well-made pin-
cers wherewith he wrought the gold. Athenee, too, came to receive
the sicrifice. And the old knight Nestor gave gold, and the other
fashioned it skilfully, and gilded therewith the horns of the heifer,
that the goddess might be glad at the sight of her fair offering."
Now at Mycenai there was found the model of an ox-head in silver,
with its horns gilded, and between them a rosette of gold, not
directly attached to the silver but to a thin copper plate. In Vapliio,
a town near Sparta, of a somewhat later period, tombs were found
containing many beautiful objects in silver, gold and bronze. Espe-
cially notew^orthy are two golden cups embossed with figures of bulls
and men ; in the one case it is a spirited hunt in the woods, in the
other a peaceful scene on the meadows. Iron, in Mycenai, appears
only as a precious metal of which finger-rings are formed. KtWo?,
which has frequently been translated "steel," was almost certainly
a blue mineral, lapis lazuli, or a carbonate of copper.

In the remains of a Greek colony in Cyprus, belonging to the
end of the Mycenaean period, which is now being explored by the
British Museum, iron plays a much more important part. At
Athens also large iron swords, which belonged to the ninth or tenth
century B.C., have been found in an old cemetery.

After this came the intellectual period of Grec'an history.
Aristotle must be mentioned in any account of the science of the
day ; and he it is who gives us the first description of the metal
mercury, and also how to produce the alloy which we call brass,
by heating together copper and calamine, the carbonate of zinc.
Metallic zinc, how^ever, was not known for many centuries after-
wards.

1898.] on the Metals used hi/ the Great Nations of Antiqiutij. 619

Conclusion.

In tracing back the history of tliese great nations we have found
evidence of a time when metals were little, if at all, employed ; the
pott( r's art was well known, and early man became wonderfully
proficient in working hard stone, and especially flint. The earliest
indications we have of metals are of gold and copper, both being
scarce, and no doubt costly. Gold was probably the earliest to attract
the attention of mankind, bectuse it occurs native, of bright yellow
colour, and is easily worked. Copper, however, dates tj a similar
period, so far as the remains which have come down to us are concerned.
1^'robably the deep blue carbonate, such as occurs in Armenia, was
first worked. AVhen silver was first used is not very evident, but
it is certain that it was far more common in the northern portion
of the area we have been considering, than in the southern. The
metallurgy of co])per was doubtless a matter of much study and
experiment so as to produce the hardest metal. This seems to have
led to the knowledge of tin, but at what precise jieriod we know not ;
nor do we know whether it was brought from Etruria, or found in
some nearer region. Mines of tin were certainly worked at Cento
Camaielle, as Egyptian scarabs liave been found in the old W(^rk-
ings,* and near Campiglia and in Elba, as well as in the Iberian
peninsula. This seai-ch for the metals, and the necessity of carrying
the ore or rough metal to the places where it was wrought, or of the
finished material to distant customers, must have greatly promoted
C(mimerce. This took place both by land and sea, in caravans
and ships. In this way tools and other objects were disseminated
through the more distant jiarts of Europe and Asia ; the similarity
of type over large areas shows a common origin, and hence we can
even roughly form an opinion as to whether they were introduced
in earlier or later times. Thus, in Switzerland and Scai:dinavia
we meet with copper imi)lements as well as bronze, and ancient as
well as modern forms ; while in Britain we find no evidence of
copfier tools, though bronze objects are abundant.

The Phcenicians, arriving on the eastern shore of the Mediter-
ranean from the direction of the Persian (lulf, formed an important
nation for about 1000 years, from B.C. 1400 to b.c. 400. They were
great artificers, but not having much originality they adopted the
patterns and designs of Egypt or Assyria. They were also j^re-
eminently traders, and founded cities and em2)oria of commerce, so
that their metal work was sj)read over all the Mediterranean. It is
to be found in Cyprus, mixed with the workmanship of the Grecian
Mycenaean age. Their ornamental jewellery was eagerly sought in
Etruria, Greece and Calabria ; for the beauty of it 1 may refer you
to the Etruscan cup of gold in the South Kensington Museum, and

* ^ee ' Early Mau iu Britain/ by Prof. W, Boyd Dawkme=

620 Dr. J. H, Gladstone on the Metals of Antiquity. [Feb. 11,

the wonderfiil work in gold in one of tlie Greek rooms in tlie British
Museum.

Commerce implies a large extension of a medium of exchange.
The whole question of money is far too wide a subject for us to deal
with now ; suffice it to say that Herodotus attributes to the Lydians
the introduction of the use of coins. The earliest were of electrum,
issued in the form of oval bullets, officially stamped on one side.
Tliey date back, perhaps, to B.C. 700 ; but, according to other autho-
rities, silver money was coined at i3i]gina more than a century before
that time.

The great period which hr,s been under our consideration ter-
minated in each country with an age of disorder and deterioration.
The rise of the Roman Empire introduced a new era : it was in one
sense an iron age — ferrum being synonymous with the sword. We
now live in another kind of iron age, but in better and brighter times
than those of Hesiod, and we may hope that our great engineering
works, our iron roads and iron steam-ships may lead not to the
enslaving but to the brotherhood of nations.

[J. H. G.]

1898.] Professor L. C. Mlall, on a YorJcshire Moor. 621

WEEKLY EVENING MEETING,

Friday, February 18, 1898.

Basil Woodd Smith, Esq. F.E.A.S. F.S.A. Vice-President,
in the Chair.

Frofessor L. C. Miall, F.R.S.

A YorJcsliire Moor.

The Yorkshire moor is high, ill-draiued, peaty, aud overgrown with
heather. Moors of this type abound in ScotLand, and creep southward
along the hills into Yorkshire and Derbyshire, breaking up into
smaller patches as the elevation declines. In the south of England
they become rarer, though famous examples occur in Dartmoor and
Exmoor. In the north they may cover great stretches of country.
It used to be said that a man might walk from Ilkley to Glasgow
without ever leaving the heather. That was never quite true, but
even to-day it is not far from the truth ; a man might walk nearly
all the way on unenclosed ground, mostly moorland.

Neither peat nor heather is confined to high ground. Peat often
forms at sea level, and may contain the remains of sea-weed. In-
some places it is actually submerged by change of sea level, and the
peasants go at low water and dig through the sand to get it. Heather
ranges from sea level to Alpine heights.

Peat may form because there is no fall to carry off the w'ater, or
because the soil, though high and sloping, is impermeable to water.
A few feet of stiff boulder clay constitute such an impermeable floor,
and a great part of our Yorkshire moors rests uj^ou boulder clay,
which is attributed to ice action, because it is often packed with ice-
scratched pebbles, some of which have travelled far, and because the
rock beneath, when bared, exhibits similar scratches.

The rocks beneatli tlie boulder clay of a Yorkshire moor are
chiefly sandstones and shales. Where the sandstones crop out, they
form tolerably bold escarpments with many fallen blocks, such as we
call " edges " in the north ; the shales make gentler slopes. Both
the surface water and the sjjring water of the moors are pure and
soft ; they may be tinged with peat, but they contain hardly any lime,
j)otash or other mineral substance except iron oxides.

The Avettest parts of the moor are called mosses (in some parts of
Scotland they aro called flow-mosses) because the S2>hagnuui moss
grows there in profusion. The Sphagnum swamps are an important
feature of the moor, if only because they form a great part of the
peat. Not all the peat, however; some is entirely composed of
heather and heath-like plants, while now and then the hair moss
(Polytrichum) and certain moorland lichens contribute their share,

622

Professur L. C. 3Iiall,

[Feb. 18,

but the Spliagnum swamps play the leading part, especially in
starting new growths of peat. If we walk carelessly over the moor,
we now and then step upon a bed of Sphagnum. We have hardly
time to notice its pale green tint and the rosy colour of the new

growths before all close observa-
tion is arrested by the cold
trickle of water into the boots.
The piactised rambler takes
care to keep out of the Sphag-
num swamps altogether, know-
ing that he may easily sink to
the knees or further. Sphagnum
sucks up water like a si)onge,
and if you gather a handlul,
you will be suiprised to see how
much water can be squeezed out
of it. This water abounds in
microscopic life ; Amoelte and
other Ehizopofls, Diatoms, In-
fusoria, Nematoids, Eotifers
and lhe like can be obtained
in abundance by squeezing a
little Sphagnum fresh from the
moors.* As the stems of Sphag-
num grow U2:)wards, they die at
the base, and form a brown
mass, which at length turns
black, and in which the micro-
scope reveals characteristic
structural details, years, per-
haps centuries, after the tissues
ceased to live.

An old Sphagnum moss is
sometimes a vast si)ongy accu-
mulation of peat and water,
rising higher in the centre than
on the sides, and covered over
by a thin living crust. The
interior may be half-liquid, and
when the crust bursts after heavy rain, the contents of a hillside
swamp now and then pours forth in an inky flood, deluging whole
parishes. In 1697 a bog of forty acres burst at Charleville, near
Limerick. In 1745 a bog burst in Lancashire, and speedily covered
u space a mile long and half a mile broad. A bog at Crowbill on the

Fio. 1. — leafy branch of Sphagnum,
magnified ; one leaf of ditto, further
magnified.

* It is interesting to note that the same abundance of animal life characterises
the mosses of Spitzln-rgen, where not a few of the very same species are found.
(U. J. Sooiirliekl, "Noii-mariue Fauna of Spitzbergcn, " ' Troc. Zoul. tSoc' 1897).

1898.

on a YorJi'shire 3Io

623

moors uear Keigliley burst in 1824, and coloured tlio river with a
peaty stain as far as to the Humber. In December 1896, a bog of
200 acres burst at Rathmore, near Killarney, and ihe eftects were
seen ten miles off. Nine persons perished in one cottage.

The soaking up of water is essential to the growth of the Sphag-
num, which employs several different expedients for this purpose.
Its slender stems give off numerous leafy branches, and also branches
which are reduced to filaments.
These last turn downwards aloug
the stem, which they may almost
C(mceal from view. The crowded
leaves have in-folded edges. There
are thus formed innumerable narrow
chinks, in which water may creep
upwards. The microscope brings
to light further contrivances, which
answer the same purpose. Many of
the cells of the leaf lose their living
substance, and are transformed into
water -holding cavities with thin
transj^arent walls, which are pre-
vented from collapsing by spirally
wound threads. But the water must
not only be lodged ; it must ascend,
and supply the growing blanches
above. Accordingly the water -
holding cells are not closed, but
pierced by many circulir pores,
which allow liquid to pass in and
out freely. Perforated water cells
also form the outer layers of the
stem. Thus the whole surface of
the plant, whether immersed or not,
is overspread by a water film, which
is easily replenished from below as
it evaporates above. It is the water
spaces which render the Sphiignum
so pale. The green living sub-
stance forms only a thin net vorh,
traversing the water-holding tissue.

Now and then we are lucky enough to see the bed of a Sphag-
num swamp. Quarrying, or a landslip, or the formation of a new
watercourse, may expose a clean section. I have known the mere
removal of big stones, time after time, from the bed of a stream fed
by a Sphagnum swamp, gradually increase the cutting power of the
running water, until the swamp is not only drained, but cut clean
through down to the solid rock. Then we may see that the peat rests
upon a sheet of boulder clay, and this upon the sandstones and shales.

Fig. 2. — Detail of Spbagnura Uaf ;
green cells with corpuscles, ami
water-cells with spiral threads
and pores. Below is a section
(from Sachs) of part of a leaf.

624 Professor L. C. Miall, [Feb. 18,

Between the peat aud the boulder clay there is sometimes fouud an
ancient seat- earth, in which are imbedded the mouldering stunij^s of
long dead trees. Oak, Scotch fir, birch, larch, hazel, alder, willow,
yew and mountain ash have been met with.* Where a great tract of
peaty moorland slowly wastes away, the tree stumps may be fouud
scattered thick over the whole surface. Above the seat-earth and its
stumps, if these occur at all, comes the peat, say from five to twenty
feet deep, aud above the peat the thin crust of living heather.

Every part of the moor has not, however, the same kind of floor.
Streams in flood may excavate deep channels, and wash out the gravel
and sand into deltas, which often occupy many acres or even several
square miles. The outcrops of the sandstones crumble into masses
of fallen blocks. Instead of the usual impervious bed of boulder-
clay, we may get a light subsoil. The verges of the moor have
commonly this character ; they are by comparison dry, well drained,
and overgrown with furze, bilberry, crowberry, fern, and wiry
grasses; such tracts are called "roughs" or "rakes" in the north of
England. A similar vegetation may be found far within the moor,
though not in places exposed to the full force of the wind. Even on
the verges of the moor there are very few earthworms, and at most
a scanty covering of fine mould ; in the heart of the moor there is no
trace of either. The Neniatoid worms which are so common in most
soils, and easily brought to the surface by j^ouring a few drops of
milk upon the ground, seem to bo absent from the humus. Insects
and insect larvae are very seldom found in it.

In a country where population and industry grow steadily, it is
rare to find the moor gaining upon the grass and woodland. Wo
have to go back some centuries to fi.nd an example on anything like
a large scale. The Earl of Cromarty (Phil. Trans. No. 330, p. 296),
writing in 1710, says that in 1651 he saw a "firm standing wood'" of
dead fir trees on a hill-side in West Eoss-shire. About fifteen years
later he passed the same spot, and found no trees, but a " plain green
moss " in their place. He was told that the trees had been over-
turned by the wind, aud afterwards covered by the moss, and further
that none could pass over it because it would not support a man's
weight. The Earl " must needs try it," and fell in up to the arm-
pits.

A section through a thick bed of peat will sometimes reveal the
manner of its growth. The lower part is often compact, the upper
layers of looser texture. It is not uncommon to find by microscopic
examination that while the lower part is made uj) entirely of Sphag-
num, the more recent growth is due to heather, crowberry, grasses,
hair moss and lichens. In some j)laces the whole thickness is of
Sphagnum only ; in others there is no Sphagnum at all. Peat formed
of Sphagnum only has no firm crust, and from the circumstances of

* Tn Yorkshire I think that birch and alder are the commonest of tlic buried

trees.

1898.]

on a Yorlishire Moor,

625

its growth it is likely to be particularly wet. Sphagnum often
spreads over the surface of i)ools or even small lakes, not nearly so
often in Yorkshire, however, as in a country of well glaciated
crystalline rocks, where lakes abound. In such cases a peculiar
kind of peat is formed as a sediment at the bottom of the water,
which may in the end fill u]) the hollow altogether. A very slight
cause is enough to start a Sphagnum bog, such as a tree falling
across a stream, or a beaver dam. When a pool forms above the
dam, the Sphagnum spreads into it, and the peat begins to grow.
Long afterwards, when the hollow is
completely filled with peat, there may
be a chance for grasses, rushes, crow-
berry and heather.

In our own time and country the
moors waste faster than they form ; it
is much commoner to find the grass
gaining on the heather than to find the
heather gaining on the grass. There
is no feature of the Yorkshire hills
more desolate than ground coveied with
wasting peat. The surface is cut up
by innumerable channels, with peaty
mounds between. These are either
absolutely bare, or thinly covered with
brown grasses and sedges. The dark
pools which lie here and there on the
flats are overhung by wasting edges of
black peat. It is cheerful to step from
this dismal territory to ground clothed
with close-growing grasses of a lively
green, such as we find where the peat
has disappeared altogether.

The moors are commonly wet, very
wet in places. In certain parts and
during certain seasons of the year they
are, however, particularly dry, and

V

Fig. 8. — Ling (Calhrna vulga^
ris). A leafy branch ; a single
leaf, seen from beneath ; and
a cross section of the base of
the leaf.

subject to a severity of drought which

the lower slopes and the floor of the valley know nothing of. At
lower levels trees give shelter from sun and wind ; night-mists check
evaporation, and even return a little moisture to the earth ; the deep,
finely divided soil lodges water, which is given off little by little, and
in our climate never fails to yield an effective supply to the roots ;
pools and streams dole out sparingly the Mater which fell lon^z before
as rain. But the moor lies fully open to sun and wind. In iMarcli it
is exposed to the east wind ; in June to hot sun and cold, clear nights ;
in August there is perhaps a long spell of drought ; in November
heavy gales with abundance of rain. Tiie summer is late ; the moor-
land grasses make little growth before the bcginnins; of June; even

626 Professor L. C. Mlall, [Feb. 18,

then the heather bears few young leaves, while the fronds of the
bracken are only beginning to pnsh through the soil. Whatever the
weather, there is no protection against its extremes; there is no
shelter and no shade. The air is cold ; wind and the diminished
pressure due to height favour rapid evaporation. Though the Sphag-
num patches form permanent bogs, a great part of the moor becomes
far drier in a hot summer than auy pasture or meadow. The top of
the peat crumbles, and is blown about as dust, the loose sand can
hold no moisture, bared surfaces of clay become hard as iron. Another
feature which must profoundly atfect the vegetation of the moor is the
poverty of its water in dissolved salts. It is pure and soft, like dis-

FiG. 4. — Transverse section of It af of Lino;, showino; large air-
spaces, the reduced lower epidermis which bears the stomates,
and the long hairs which help to close the cavity into which
the stomates open.

tilled water, and contains hardly any mineral food for plants. The
plants of the moor are subject to the extremes of wet and dry, to cold
and to famine.

The best known and most characteristic of the moorland plants
are the heaths. Ling, the common heather, is the most abundant of
all; it sometimes covers many square miles together, to the almost
complete exclusion of other plants. Ling is a low shrub, wliose wiry
stems creep and writhe on the surface of the ground. When sunk
in deep peat the stems are often pretty straight, but among rocks you
may follow the twisted branches for many yards, and at last discover
that what you took for small plants rooted near the surface are really
the tops of slender trees, whose roots lie far below. Bilberry, too,
wriggles among loose stones or fallen blocks till you grow weary of
following it. The leaves of ling are dry, hard and evergreen. They
last for two or three years, and do not fall ofi' as soon as they die,

1898.'

071 a YovTisliire Moor.

627

but crumble slowly away. They are very small, densely crowded,
and ranged ou the branch in four regular rows. A good thin section
through a leaf is not easy to cut ; when you get one, you find that
the interior is largely occupied by irregular air spaces, and that the
stomates are sunk in a deep groove on the under side of the leaf,
where they are further sheltered by hairs.

Fig. 5. — Cross-leaved Heath {Erica tetraUx); with part of a branch,
enlarged ; a leaf seen from the under side ; and a section of a leaf.

Ling is a plant of slow growth, and a stem which showed seven-
teen annual rings was only a centimetre in diameter. Stems of
greater age than this are rare. After ten or twelve years the plants
flower scantily, and exhibit other signs of age. Then the common
practice is to burn them off.

As we travel south, we find the ling getting smaller and smaller.
In Scotland it is often waist-deep, in Yorkshire knee-deep, on
Dartmoor only ankle-deep. On the moors of the south of England
the ling is generally much mixed up with grasses, as also on the
verges of the Yorkshire moors. In Cornwall it may grow so close
to sea level that it is wet with salt spray in every storm, and its tufts

628 Professor L. C. Mtall, [Feb. 18,

are intermingled with sea-pink and sea-plantain. At the Lizard,
wherever the serpentine comes to the surface, ling ceases, and the
Cornish heath (Erica vagans) takes its place.

Here and there we find among the ling the large-flowered heaths
with nodding pink or purple bells (Scotch heath, cross-leavei
heath). The leaves of these plants are much larger and thinner
than those of ling ; they are called " rolled leaves," because the edges
curve downwards and inwards, partly concealing the under surface,
which bears the stomates. All our native heaths agree in possessing
wiry stems, long roots and narrow evergreen leaves, with a glossy
cuticle and small transpiring surfaces. The tissues are very dry,
and burn readily even when green or drenched with rain. It is
possible by good management to set acres of heather in a blaze, even
in midwinter, with a single lucifer match. The heaths wither very
slowly when gathered, and change little in withering.

Some of these features are characteristic of desert plants. Many
desert plants have reduced transpiring surfaces and hidden stomates.

Fig. 6. — Transverse section of roller! leaf of cross-leaved
Heath {Erica tetralix).

They often have very long roots, as was particularly obseived in the
excavations for the Suez Canal.* The leaves are often small and
crowded, the stems woody, much branched and tufted. Bright sun-
light retards growth, and green tissues hardly ever present a large
absorbing surface when they are habitually exposed to bright light.
Accordingly the young shoots and branches do not push out freely,
but try to hide one behind another. The tissues of desert plants may
be remarkably dry ; they are often, however, remarkably succulent ;
the plant either learns to do without water for a long time together,
or to store it up.

It is not without surjn'ise that we learn how similar are the effects
of tropical drought and of Arctic cold. The facts of distribution
would in themselves suffice to show that our moorland heaths are
well fitted to endure great cold. Ling extends far within the Arctic
circle, though it seldom covers large surfaces there, and it rises to

* Examples are quoted by Warming. ' Lehrb. d. okol. Pflanzengeographie/
p. 198.

1898.] on a Yorkshire Moor, 629

2000 metres (6600 feet) on the north side of the Alps. It extends
soutliward to the shores of the Mediterranean. Our large-flowered
heaths have not been traced quite so far north as ling, and they are
not found on the Alps, though they inhabit the Pyrenees. Many
representatives of the heath family, with like structure of leaves, are
found in the extreme north of the American continent. Those
features which assimilate our heaths to desert plants, and which
seem to be obvious adaptations to a situation of extreme drought, are
equally serviceable to plants which have to face boisterous winds and
low temperature. The shrubs of the far north are low, tufted, small-
leaved, evergreen and dry — just like the heaths of our moors.
Middendorff* shows how the Dahurian larch becomes stunted in
proportion to increasing cold. Before it disappears altogether, it is
cut down to a prostrate creeping shrub. One such dwarf larch,
though 150 years old, was only a foot or two across. Plants much
exposed to biting winds must make the most of any shelter that can
be had ; their branches push out timidly, and for a very short
distance ; the leaf surface is reduced to a minimum ; since the warm
season is short, evergreen leaves are profitable, for they enable the
j^lants to take advantage of early and late sunshine.

The heaths and many other moorland plants bear the marks of
the Xerophytes, or drought plants. Xerophytes grow under a con-
siderable variety of conditions, some of which do not suggest drought
at first sight, but their tissues are always ill'Supplied with water.
It may be that w^ater is hardly to be had at all, as in the desert ; or
that water must not be imbibed in any quantity because of low
temperature, as in Arctic and Alpine climates ; or that the water is
mixed with useless and perhaps injurious salts, from which it can
only be separated with great difficulty, as in a salt marsh. Whatever
may be the reason for abstinence, xerophytes absorb water slowly^
part with it slowly, and endure drought well.

In the case of moorland plants there is an obvious reason why
many of them, though not quite all (Sphagnum is one exception)
should rather thirst and grow slowly than pass large quantities of
water through their tissues. The water contains hardly any potash
or lime, and very little that can aid the growth of a plant. But it is
probable that this is not the sole reason. Except where special
defences are provided, it is dangerous for a plant which may be
exposed to wind or low temperature to absorb much water.

The Bilberry (or Blueberry, as w^e ought to call it) is one of the
few exceptions to the rule that moorland plants are evergreen j it
casts its leaves in early winter. But the younger stems are green,
and take upon themselves the function of leaves when these are
absent. Keruer has described one adaptation of the bilberry to
seasons when water is scarce. Many plants, especially those of hot
and wet climates, throw off the rain water from their tips, and so

* ' Sibirische Reise,' vol. iv. p. 605.
Vol. XV. . (No. 92.) 2 t

630

Professor L. C. 3Iiall,

[Feb. 18,

keep tlio roots comparatively dry ; others direct the water down the
branches and stem to the roots. Bilberry is one of the latter sort.
The rounded leaves slope downwards towards the leaf stalk, and

from the base of every leaf
stalk starts a pair of grooves,
which are sunk in the sur-
face of the stem. A light
summer shower is economised
by the guiding of the drops
towards the roots. Bilberry
abounds on the loose and
sandy tracts of the moor, and
especially on its verges ; it
is seldom found upon a deep
bed of peat.

There is a moorland plant
which may be said to mimic
the heaths, as a Euphorbia
mimics a Cactus, or Sarra-
cenia a Nepenthes. Simi-
larity of habit has brought
about similarity of structure.
The plant I mean is the
Crowberry, which is so like
a true heath in its foliage
and manner of growth, that
even the botanists, who did
not fail to remark that the
flowers are altogether dif-
ferent, long tried to bring
the crowberry and the heaths
as near together in their
systems as they could . Crow-
berry has the long, dry, wiry
stems, the small, narrow,
rolled, clustered, evergreen
leaves of a true heath. The
leaf margins are turned back
till they almost meet, and
the narrow cleft between
them is obstructed by close-
set hairs, so that the trans-
piring surface is effectually
sheltered. Crowberry is a
peat-loving shrub, and is often found with ling and other heaths in
the heart of the moor. The berries are a favourite food of birds,
which helj) to disseminate the species. Crowberry has an un-
commonly wide distribution, not only in the Arctic and Alpine

Fig. 7. — Crowberry (Empetrum nigrum').
A staminate branch, slightly enlarged;
a, part of a pistillate branch ; 6, one sta-
minate flower ; c, one pistillate flower.

1898.]

on a Yorksldre Moor.

631

regions of the Old World, but also in the New, It abounds in
Greenland, where the Eskimo use the berries as food, and extract a
sjDirit from them. A very similar species, with red berries, occurs iu
the Andes.

The heaths, bilberry, crowberry, and many other peat-loving
shrubs or trees, have a peculiar root structure. The usual root hairs
are wanting, and in their place we find a peculiar fungus-growth,
which invades the living tissues of the root, sometimes penetrating
the cells, There is often a dense mycelial mantle of interwoven
filaments, which covers all the finer roots. This looks like parasitism,

Fig. 8. — Cross section of leaf of Crowberry. The lower figures
show one of the peculiar hairs and one of the stomates. Both
are confined to the inner, which is properly the under surface.

but the fungus is apparently not a mere parasite, for the tree or shrub
shows no sign of injury, but thrives all the better when the fungus
is plentiful, and may refuse to grow at all if the fungus is removed.
Ehododendron, ling, most heaths, bilberry, crowberry, broom,
spurgeJaurel, beech and birch are among the plants which have a
mycelial mantle. If the native soil which clings to the roots of any
of these is completely removed, if the fine roots with the mycelial
mantle are torn off by careless transplanting, or if peaty matter is
withheld, the plant dies, or struggles on with great difficulty until
the mycelial mantle is renewed. Such plants cannot, as a rule, be
propagated by cuttings, unless special precautions are taken. Frank

2 T 2

632 Professor L. C. Miall, [Feb. 18,

maintains that tlie mycelial mantle is the chief means of absorption
from the peaty soil, and that the tree or shrub has come to depend
upon it. The known facts render this interpretation probable, but
thorough investigation is still required. In some cases at least the
j)lant can be gradually inured to the absence of a mycelial mantle.
I have repeatedly planted crowberry in a soil devoid of peat. It
generally succumbs, but when it survives the first year, it maintains
itself and slowly spreads. Microscopic examination shows that the
roots of crowberry grown without peat contain no mycelial filaments
or very few. The special function of the fungus may be to reduce
the peat to a form capable of absorption as food by green plants. It
is likely that the fungus gains protection or some other distinct
advantage from the partnership. Most of the species of green plants
which have the mycelial mantle are social. It is obvious that the
fungus will be more easily propagated from plant to plant, where
many trees or shrubs of the same species grow together.

Fig. 9. — Lougitudinal section of root of Ling (Calluna vulgaris), sLowing
mycorhizal filaments in outer cells.

The grasses of the moor are marked xerophytes with wiry leaves,
whose look and feel tell us that they have adapted themselves to
drought and cold by reducing the exposed surface to a minimum. A
section of the leaf of Nardus, Aira flexuosa or Fesfcuca ovina shows
that the upper surface, which in grasses bears the stomates, is
in-folded, and sometimes greatly reduced. Advantage has been taken
by these grasses of a structure which was apparently in the first
instance a provision for close folding in the bud. The upper stomate-
bearing surface is marked by furiows with intervening ridges, and
where the folding is particularly complete, both furrows and ridges
are triangular in section, and the leaf, when folded up longitudinally.,
becomes an almost solid cylinder. In the grasses of low, damp
meadows, the j)ower of rolling up may soon be lost by the leaves.
Other grasses, which are more liable to suffer from drought, retain in
all stages the povrer of rolling up their leaves. Sesleria cserulea, for
instance, which covers large tracts of the limestone hills of Yorkshire,
can change in a few minutes from closed to open, or from open to.
closed, accordinpf to the state of the air. The leaves of the true

1898.]

on a Yorlishire Moor,

633

moorland grasses (Nardus, Aira flexuosa, Festuca ovina) are per-
manently in-rolled, and flatten out very slowly and imperfectly, even
when immersed in water for many hours.

Onr moorland grasses are all arctic, and occur both in the old
and the new worlds ; Festuca ovina is also a grass of the steppes ; it
is world-wide, being found in all continents, especially on mountains,
and even reaching Australia and New Zealand.

It may seem paradoxical to count the Rushes as plants which are
protected against drought, for they often grow in the wettest part of
the moor. They are common, however, in dry and stony places, and

Fig. 10.

-Transverse section of leaf of Nardns stricta^
showing permanent in-rolling.

their structure is completely xerophytic. The leaves are often
reduced to small sheaths, which wither early, while the stems are
green, and perform the work of assimilation; or else, as happens in
certain species, the leaves assume the ordinary structure of the stem.
The cylindrical form of the rush stem is significant, for of all
elongate solid figures the cylinder exposes the smallest surface in
proportion to its volume. Moreover a cylindrical stem, without
offstanding leaves, and alike on all sides, is w^ell suited, as Jungner
points out, to the circumpolar light, which shines at low angles from
every quarter in succession. A rush stem is singularly dry, the

634 Professor L. G. Miall, [Feb. 18,

centre being occupied by an abundant pith of star-shaped cells,
which entangle much air.

The Hair moss (Polytrichum commune) of the moor has a delence
against sun and wind, which has been described by Kerner. The
leaf has wings, like an altar piece, which can open and shut. The
assimilating surface occupies the centre, and rises into many green
columns. In wet or cloudy weather the wings open wide, but when
the sun shines they fold over the columns, and protect them from
scorching.

All the most characteristic plants of the moors are Arctic, 1-ing,
bilberry, crowberry, certain rushes, Nardus, Festuca ovina, most of
our club mosses, the hair moss and Sphagnum range withm the

Fig. 11. — Transverse section of leaf of Aira Jtexnosd.

Arctic circle; while the large-flowered heaths get close up to it.
Most of them are found on both sides of the Atlantic, and some, like
the crowberry and Festuca ovina, have a singularly wide distribu-
tion.

It has often been pointed out that great elevation above sea level
produces a similar effect upon the flora to that of high latitude. In
the Alps, the Pyrenees, the Himalayas, and even in the Andes, the
forms characteristic of northern lands reappear, or are represented
by allied species. Where, as in the case of the Andes, nearly all the
species differ, it is hard to draw useful conclusions, but whenever the
very same species occur across a wide interval the case is instructive'.
In the Alps we find our moorland and Arctic flora almost complete,
though Eubus Chamsemorns, Erica Tetralix, and E. cinerea (both

18980

on a Yorkshire Moor.

635

found in the Pyrenees), Narthecium ossifragum and Aira flexuosa
have disappeared.

A favourite explanation rests upon the changes of climate to
which the glaciation of the northern hemisphere bears emphatic
witness. When the plains of Northern Europe were being strewn
with travelled boulders, when Norway, Scotland and Canada were
covered with moving ice, the vegetation of Siberia and Greenland
may well have extended as far south as Switzerland.

I do not doubt the general truth of what we are taught respecting
the glacial period, but I think that we are apt to explain too much
by its help. We know very little
for certain as to its effect upon
vegetation. Our information con»
cerning the prcglacial flora is ex-
tremely meagre, nor are we in a
230sition to say positively what
sort of flora covered the plains of
Europe after the severity of glacial
cold had passed away, and before
men had changed the face of the
land by tillage.* We know rather
more about the animals of these
ages, for animals leave more recog-
nisable remains than plants, but
the indications of date, even in the
case of animals, are apt to be slight
and uncertain. On the whole, 1
doubt whether the glac'al period
marks any great and lasting change
in the life of the northern hemi-
sphere, f I think it probable that
since the glacial period passed

away, the countries of Central .

ifcurope posses.sed many species, both of plants and nnimals, which we
should now consider to be Arctic, and that these Arctic species endured
until many of them were driven out by an agent of which geologists
usually take little notice. I shall come back to this point.

'I'he animal life of tlie Yorkshire moors is not abundant. Hares,
shrews, stoats, weasels and other small quadrupeds, which are
plentiful on the rough pastures, cease whei-e the heather begins.
There are a good many birds, some of which, like the grouse, the

Fig. 12. — Transverse se(;tion of leaf of
Feshica ovina. In tliick sections
hairs are seen to point iuwafdg
from the inner epidermis.

* Some information has been gained by investigation of plant reniains found
beneath the bogs of Denmark, and beneath the palseolithic brick-earth at
Hoxne.

t It is well known that this position has been strongly maintained by Professor
Boyd Dawkins ("Early Man in Britain," p. 123,&c. ' Q. J. Geol. Soc' vol. xxxv.
p. 727, and vol. xxxvi. p. 391>). On the other side. Dr. James Geikie may be
consulted ('Prehistoric Europe,' ch. iii, &n.).

6S6

Professor L. C. MiaU,

[Feb. 18,

ring-ouzel, the twite, or mountain-linnet, the curlew, and the golden
plover, seek all their food on the moor, except in the depth of winter,
when some of them may visit the sea-coast, or the cultivated fields^
or even southern countries. The kestrel, blackbird, whinchat, stone-
chat, night-jar and lapwing abound on the " roughs " or border-
pastures rather than on the moor itself. Owing to the absence of
tarns and lochs there are practically no water-fowl. Gulls are hardly
ever seen, though they are common enough on the Northumberland
moors. Now that the peregrine, golden eagle and hen-harrier are

Fig. 13. — Transverse section of stem of Ru<h {Juncus conglomeraius),
showing the stellate pith cells, and very numerous air spaces.

exterminated, the chief moorland birds of prey are the merlin, kestrel,
and sparrow-hawk. Of these, only the merlin is met with in the wilder
parts of the moor, where it flies down the smaller birds. The kestrel
hovers over the roughs, on the look-out for a mouse or a frog. The
sparrow-hawk preys upon small birds, but rarely enters the heart of
the moor.

To most people the interest of the moor centres in the grouse.-
There are many things about grouse which provoke discussion, such
as its feeding times, or the grouse-fly, and what becomes of it during

1898.] on a Yorkshire Moor. 637

the months when the grouse are free of it. But the absorbing topic
on which every dweller by the moor is expected to have an opinion,
is the grouse disease.

All sorts of causes Lave been assigned, such as over-stocking of
the moors, destruction of the large hawks which used to kill off ailing
birds, parasitic worms, cold, deficiency of food, and so on. Some
Yorkshire sportsmen have attributed the disease to the scarcity of
gritty sand. On shale-moors, tbey maintain, the gizzard of the
grouse is filled with soft stones, which will not grind up the heather-
tops effectively, except when they are young and tender. On sand-
stone moors the grouse can deal with tougher food, and there the
disease, it is sa'd, is unknown. Dr. Klein's researches * show that
the disease is really due to the multiplication within the body of a
specific germ, which is fungal, but not bacterial. The infection is
conveyed, or may be conveyed, by the air.

The viper is rare, and until quite lately I had never heard of its
presence on our Yorkshire moors. Lizards are also rare, but efts are
not uncommon. Among the moorland moths are many small Tineina
(allied to the clothes moth). The caterpillar of the emj^eror moth
is characteristic, and seems to be protectively coloured, for it wears the
livery of the heather — green and pink. The moths which issue from
these larv8B are captured in great numbers by Sunday ramblers, whd
resort to the base contrivance of bringing a female moth in a cage^
The self-styled " naturalist " sits on a rock, and captures one by ond
the eager moths which come about him, afterwards pinning out the
expanded wings to form grotesque patterns, or selling his specimens
to the dealers. Certain wide-spread Diptera are plentiful, and there
are a few which pass their larval stages in the quick-running streams
which flow down from the moor. The small number of good-sized
insects partly exj)lains (or is exj)lained by) the paucity of conspicuouSj
scented or honey-bearing flowers. In this the moor contrasts strongly
with the higher Aljjs. Bees, however, get much honey from the
large-flowered heaths and ling ; heather-honey is considered better
than any other. A little scale insect (^Orthesia uva) has been found
plentifully on the Sphagnum of the moors, particularly in C'umber-
land.f A big spider (^E^eira diadema) spreads its snare among the
heather, and may now and then be seen to deal in a particularly
artful fashion with a wasp or other large insect which may have
blundered into the web. The spider cuts the threads away till the
struggling insect dangles ; cautiously on outstretched leg holds out
and attaches a new thread, and then sets the wasp spinning. The
silken thread, paid out from the spinneret, soon binds the victim into
a helpless mummy.J I have never found gossamer so abundant as
on the verges of the moor.

* ' The Etiolop;y and Pathology of Grouse Disease, &c.' (1892).
t Shaw (180G) quoted by R. Blanchard in ' Ann. Soc. Eiit. Fr.' torn. Ixv.
p. 681 (1896). i Blackwall's ' Spiders/ vol. ii. p. 359.

638 Professor L. G. Midi, [Feb. 18,

In our day the Yorkshire moor harbours no quadrupeds, and the
grassy hills none but small quadrupeds. It was not always so. At
Eaygill, a few miles from us across the moors, a collection of bones
was discovered a few years ago in quarrying. A deep fissure in the
rock had been choked ages before with stones and clay. This fissure
was cut across by the working face of the quarry. Many bones were
brought out of it, bones of the ox and roebuck among the rest. But
mixed up with these were teeth and bones of quadrupeds now alto-
gether extinct or no longer found in Britain, such as the straight-
tusked elephant [E. antiqmis), the hippopotamus, a southern rhinoceros
(B. leptorhimis), the cave by ana, and the European bison. The Irish
(Ik is often dug up in Yorkshire, the reindeer and the true elk now
and then. Not very long ago these and other large quadrupeds
grazed or hunted a country which can now show no quadruped
bigger than a fox.

It is evident that the moors, valleys and plains of Y^orkshire have
been depopulated in comparatively recent times. The disappearance
of so many conspicuous species is commonly attributed to the glacial
period, but I think that the action of man has been still more
influential. The extinct animals are such as man hunts for profit or
for his own safety. Many of them, among others the cave bear,
Machairodus, Irish elk, mammoth, and straight-tusked elephant, are
known to have lasted inta the human period. That so many of them
were last seen in the company of man is some proof that he was
concerned in their death.

Central Europe, before man appeared within its borders, or while
men were still few, little resembled the Europe which we know.
Much of it was covered with woods, morasses or wastes, and inhabited
by animals and plants, of which some ranged into the Arctic circle,
others to the Mediterranean, Africa and India. The worst lands of
all — cold, wet, and wind-sw^ept — had doubtless then, as now, the
greatest proportion of Arctic species. But it is likely that the
passage from the bleak hills to the more fertile valleys and plains
was not then so abrupt as at present. All was al.ke undrained and
unenclosed ; and what we know of the distribution of life in Pleisto-
cene Europe shows us that a large proportion of ojir European
animals and plants are not restricted by nature within narrow limits
of latitude or climate. Species which are now isolated, at least in
Central Europe, occupying moors or other special tracts, and sur-
rounded by a population with which they have little in common,
were formerly continuous over vast areas. In the early days of man
in Europe many plants, birds and quadrupeds which are now almost
exclusively Arctic may well have ranged over nearly the whole of
Europe.

As men gradually rooted themselves in what are now^ the most
populous countries of the world, the fauna and flora underwent
sweeping changes. The forests were cleared, and trees of imported
species planted here and there; The land was drained, and fenced^

1898.] on a Yorkshire Moor, 639

and tilled. During the long attack of man npon wild nature many
quadrupeds, a few birds, some insects and some plants are known to
have perished altogether. Others have probably disappeared with-
out notice Certain large and formidable quadrupeds, though they
still survive, are no longer found in Europe, but only in the deserts
of the south or the unpeopled northern wastes. Thus the lion, which
within the historic period ranged over Greece and Syria, and the
grizzly bear, which was once an inhabitant of Yorkshire, have dis-
appeared from every part of Europe. Tillage and fencing have
checked the seasonal migrations of the reindeer and the lemming.
Useful animals have been imported, chiefly from the south or from
Asia. Useful plants have been introduced from ancient centres of
civilisation, and common farm weeds have managed to come in along
with them. Many species of both kinds are southern, many eastern,
none are Arctic. In our day the cultivated lands of Europe are
largely occupied by southern or eastern forms, and the wastes appear
by contrast with the imported population more Arctic than they really
are. Even the wastes are shrinking visibly. The fens are nearly
gone, and we shall soon have only a few scattered moors left to show
what sort of vegetation covered a great part of Europe in the days of
choked rivers and unfenced laud. The moors themselves cannot
resist the determined attack of civilised man. Thousands of acres
which used to grow heather are now pastures or meadows.

What we call the Arctic fauna and flora of to-day is apparently
only the remnant of an assemblage of species varying in hardinesSj
which once extended from tlie Arctic circle almost to the Mediter-
ranean. If climate and soil alone entered into tbe question, it is likely
that the so-called Arctic fauna and flora miglit still maintain itself
in many parts of Central Europe. This Arctic (or ancient European)
flora includes many plants which are capable of withstanding extreme
physical conditions. Some thrive both on peat and on sand, in bogs
and on loose gravel. They may range from sea level to a height of
several thousand feet. They can endure a summer glare which
blisters the skin, and also the sharpest cold known npon this planet.
Some can subsist on soil which contains no ordinary ingredient of
plant food in appreciable quantity. Such plants survive in particular
places, even in Britain, less because of peculiarly appropriate sur-
roundings, or of anything which the microscope reveals, than because
they can live where other plants perish. Ling, crowberry and the
rest are like the Eskimo, who dw^ell in the far north, not because
they choose cold and hunger and gloom, but because there only can
they escape the competition of more gifted races. The last defences
of the old flora are now being broken down ; it is slowly giving way
to the social grasses, the weeds of commerce, and the broad-leaved
herbs of the meadow, pasture and hedge-row. The scale has been
turned, as I think, not so much by climatic or geographical changes,
as by the acts of man.

Every lover of the moors would be glad to know that they bid

640 Professor L. C. Miall, on a TorJcshire Moor. [Feb. 18,

fair to be handed down to our children and our children's children
without diminution or impoverishment. The reclaiming of the moors
is now checked, though not arrested, and some large tracts are re-
served as open spaces. But the imj)overishment of the moors goes
on apace. The gamekeeper's gun destroys much. Enemies yet
more deadly are the collectors who call themselves naturalists, and
the dealers who serve them, A botanical exchange club has lately
exterminated the yellow Gagea, which used to grow within a mile of
my house. "Whenever a kingfisher shows itself, young men come
from the towns eager to slay it in the name of science. No know-p-
ledge worth having is brought to us by such naturalists as these ;
their collecting means mere destruction, or at most the compilation
of some dismal list. If the selfish love of possessing takes hold of
any man, let him gratify it by collecting postage-stamps, and not
make hay of our plants and mummies of our animals. The naturalist
should aspire to study live nature, and sliould make it his boast that
he leaves as much behind him as he found.

[L, C. M.]

1898.] Becent Besults of FhysicO'Cliemical Inquiry. 64:1

WEEKLY EVENING MEETIN

Friday, March 4, 1898.
Sm William Crookes, F.K.S. Vice-President,
Professor T. E. Thorpe, LL.D, F.Pt.S.

Some Recent Results of Physico- Chemical Inquiry.

The lecturer gave an account of the main results of an investigation
on the relations between the viscosity (internal friction) of liquids and
their chemical nature which had occupied the late Mr. J. W. Eodger
and himself during several years. He pointed out, in the first
place, that the many attempts which had been made since Hermann
Kopp directed attention to the connection which exists between the
molecular weights of substances and their densities, to establish
similar relationships between the magnitudes of other physical
constants and chemical composition, had rendered it highly probable
that all physical constants are to be regarded as functions of the
chemical nature of molecules, and that the variations in their mag-
nitude observed in passing from substance to substance are to be
attributed to changes in chemical composition. As yet, however, all
endeavours to connect the chemical nature of liquids with their
viscosity have been only partially successful, although it is obvious
from the work of Graham, Rellstab, Pribram and Haudl, and Garten-
meister, that such a connection ought to be discoverable.

Thus it was known that an increment of CH2 in a homologous,
series is in general accompanied by an increase in viscosity, and
that the increase is greater when the increment of CH2 takes place
in an alcohol radicle than when it takes place in an acid radicle,
Metameric bodies have, in general, different viscosity values, and
these are nearer together the nearer the boiling points of the liquids.
Substances containing double-linked carbon are more viscous than
those of equal molecular weight containing single-linked carbon.
The substitution in a molecule of CI, Br, I and NO2 for H in all
cases increases the viscosity of the substance. This increase is
smallest on the introduction of CI, and increases on the introduction
of Br, I, and NO2 and in the order given. The absolute amount of
the increase depends not only upon the nature of the substituting
radicle but also upon its position in the molecule. Of two isomeric
esters that possesses the greater viscosity which contains the higher
alcoholic radicle. The ester containing the normal radicle has always,
a greater viscosity than the iso-compound, and this obtains no matter

642 Professor T. E. Thorpe [March d,

whether the isomerism is in the alcohol or the acid radicle. The
normal aldehydes have invariably a greater viscosity than the iso-
compounds, whilst the alcohols have a greater viscosity than the
correspondicg aldehydes and ketones. The introduction of the
hydroxyl group into the molecule greatly increases the viscosity of
the liquid. This is strikingly illustrated by the instances of propyl
alcohol, propylene glycol and glycerin. Indeed the high viscosity
of solutions of carbohydrates, e.g. the sugars, gums, &c., is probably
dependent on the relatively numerous hydroxyl groups in the mole-
cule. The manner in which tlie hydroxyl group is combined seems,
however, to have considerable influence on the viscosity. Thus in
the cases of the isomeric substances, benzyl alcohol and metacresol,
it is found that in the first-named substance, in which the hydroxyl
group occurs in the side chain, the viscosity is very much less than
that of the second, in which the hydroxyl group is attached to a carbon
atom in the benzene ring.

Whilst the broad fact of a connection between the viscosity of a
liquid and the chemical nature of its molecules is established, it
cannot be said that the numerical results hitherto obtained ajSbrd any
accurate means of determining the quantitative character of this con-
nection. This is owing partly to the imperfection of observational
methods, and partly to the uncertainty of the basis of comparison. It
seems futile to expect that any definite stoichiometric relations should
become evident by comparing observations taken at one and the same
temperature. Hitherto few attempts have been made to ascertain
the influence of temperature upon viscosity, and hence the law of the
variation is unknown. It seemed therefore, obvious, that in order to
investigate the subject with reasonable hope of discovering stoichio-
metric relations, one essential point was to ascertain more precisely
the influence of temperature on viscosity, and then to compare the
results under conditions which have been found to be suitable in
similar investigations in chemical j)hysics. Unfortunately, the accu-
rate determination of absolute coefiScients of viscosity is beset with
difficulties, both in the theory and practice of the methods which can
be employed. Moreover, it is quite possible that even if accurate
values of the coefficients of viscosity were obtained, their relationships
to chemical composition might not be simple. Viscosity is, no doubt,
the nett result of at least two distinct causes. When a liquid flows,
during the actual collision or contact of its molecules a true friction-
like force is called into play which opposes the movement, whilst at
the same time molecular attractions exercise a resistance to the forces
which tend to move one molecule past another.

After indicating the meaning of viscosity and the principles
involved in measuring it, the lecturer proceeded to point out how
the coefficient of viscosity may be defined. It is the force which is
necessary to maintain the movement of a layer of unit area past
another of the same area with a velocity numerically equal to the
distance between the layers when the space between them is con-

1898. J on Some Becent Besults of Physico-CJiemical Inquiry. G13

tinuously filled with the viscous substance. He then described the
different modes of measuring viscosity, and explained the general
principle of the method and the features of the particular apparatus
employed in the investigation made by Mr. Rodger and himself. The
princij^le was that of Poiseuille, and consisted in observing the time
required for a definite volume of liquid under a definite pressure to
pass through a capillary tube of known size, the temperature being-
known and kept constant during the interval. The actual apparatus,
however, differed in many important features from any previously
designed for the same purpose, and admitted of the determination, in
absolute measure, of the coefiicient for a tempemture range from
0° up to the ordinary boiling point of the liquid. In most of the
instruments used by previous observers, the liquid, after passing
through the capillary, was allowed to escape, and hence the apparatus
had to be recharged before another observation
could be made. In the newer form, the time ^ '^

spent in recharging was saved, by arranging
that in all the observations on any one liquid
the same sample could be used repeatedly ; and
further economy in time was obtained by ar-
ranging that observations could be taken while
the liquid was flowing in either direction through
the capillary tube, and that while an observation
was in progress and liquid was leaving one por-
tion of the instrument, it was entering another
portion and getting into position for a fresh ob-
servation. It was also desirable to avoid the use
of corks or caoutchouc in such parts as would be
in contact with the liquid, and it was therefore
necessary that the instrument should be made
entirely of glass.

The form of apparatus designed to meet these
requirements is shown in Fig. 1 ; it may be
termed a glischrometer. It consists of two up-
right limbs L and R (left and right), connected
near their lower ends by a cross piece. Within
the cross piece is the capillary tube C P, the
bore of which is about • 008 centimetres radius,
and the thickness of the wall about 2 millimetres,
the internal radius of the cross piece being a
millimetre or so greater than the external radius
of the capillary. At the zone R, R'^, the walls of
the cross piece are constricted and made con-
tinuous with those of the capillary : the latter
is thus gripped at its middle portion and held axially within the
cross piece. Care is of course taken that the bore of the capillary is
in no wise disturbed during the process of sealing.

On one side of each limb of the instrument three fine horizontal

644 Professor T. E. Thorpe [March 4,

lines were etched, m\ m^, h^, on tLe left limb ; m^, w*, 7c^, on the right
limb. The volumes of the limbs between m^ and m^ and between m^
and m* were carefully determined ; these rejiresent the volumes of
liquid which flow through the ca2)illarj. The time taken by the level
of the liquid to pass from the upi^er to the lower of either of these
pairs of marks is the time observed in the experiments. The limb is
constricted in the vicinity of the marks, in order to give sharpness in
noting the coincidence of the meniscus with the mark. The shape of
the limb between the marks was made cylindrical rather than spherical,
in order that the contained liquid might the more readily acquire the
temperature of the bath in which the glischrometer was placed during
an observation.

It will be seen from the figure that the upper ends of the limbs
H^, H'-^ terminate within the glass traps T^, T'^. These traps admit
of slight adjustments of the volumes of liquid contained in the limbs,
and their use is connected with that of the marks h^ and 1c-. During
an experiment the levels of liquid in the two limbs are continually
altering. The object of these marks and trajDS is to ensure that at the
beginning of any observation in a particular limb the effective head
of the liquid contained in the glischrometer shall be constant and
shall be known. Let us sujDpose that an observation is to be made in
the right limb ; the liquid level in the left limb is just brought into
coincidence with the mark k^, when any excess of liquid will flow
over into the trap T^ ; hence the effective head of liquid extends
from H^ to k^, and is thus known. A similar proceeding is carried
out for the left limb observations, using the mark P and trap T^.
The marks k^ and k'^ are placed by trial in such positions that the
volume from k^ to H^ is almost equal to, but slightly greater than,
that from P to H^. The volumes F- H^ and P H^ are the working
volumes of liquid used in the observations.

The general arrangement of the whole apparatus is shown in
Fig. 2. A bath B, which for observations at temperatures below
100° contains water, and for higher temperatures glycerin, is sup-
ported on an iron stand which is placed on a table in front of a
window.* The bath is divided into two compartments. The inner
compartment is provided back and front with i3late glass walls ; the
rest of the bath is made of brass. The outer compartment bounds
the inner at the sides and underneath, and is fitted with a tap for
adjusting the quantity of liquid which it contains. The brass frame-
work carrying the glischrometer, and thermometer T, can be lowered
into vertical slots in the lateral walls of the inner compartment ;
when thus situated the glischrometer occupies a central position in
the bath. The walls of both compartments are provided with guides,
along which move stirrers consisting of brass plates pierced with
holes, which are attached to suitable rods and cross pieces, and are
worked by a small water-motor W M.

* In practice two baths were used, one containing water, the other glycerin.

1898.] on Some Becent Besulfs of PJiysico-Chemical Inquiry. 645

Fig. 2.

Vol. XV. (No. 92.)

2 u

646 Professor T. E. Thorpe [March 4,

The rubber tube E connects the right limb of the glischrometer
with the glass tube 0, in which is inserted the three-way cock Z. In
the same way E' connects the left limb of the glischrometer with the
tube 0' fitted with the three-way cock Z'. At P, O and 0' are united
by a T piece which leads to the bottle M containing a quantity of
sulphuric acid, which can be abstracted or replaced by means of the
syphon W. The acid serves to dry air in its passage from the reser-
voir L to the glischrometer. When hygroscopic liquids are being
experimented upon, the exit tubes of the three-way cocks are provided
with small tubes filled with calcium chloride to prevent access of atmo-
spheric moisture to the glischrometer. In this way it is insured that
dry air only is in contact with the liquid under examination.

By means of the tube N, which extends from within a few milli-
metres of the surface of the acid in M to a centimetre or so below
the cork L', and which is fitted with the cock Q, the air in M may be
put into communication with the large air reservoir L. This con-
sists of a glass bottle of about 30 lities capacity, encased in a wooden
box, and surrounded with sawdust to prevent excessive fluctuation
of temperature. A glass tube A', which reaches to within 5 milli-
metres, of the bottom of L, is connected, as shown, by india-rubber
tubing with the water reservoir E. The air in L is compressed by
raising the water reservoir, the height of which can be regulated by
a cord leading by a system of pulleys to the stud X, in close proximity
to the observer, and to the water manometer D D which indicates the
pressure set up in the confined air space. The manometer is con-
nected with the air reservoir by the tube I I, which has a common
termination with the tube N.

After describing the method of making a viscosity observation, the
lecturer proceeded to indicate how the coefficients of viscosity for the
particular temperatures were deduced from the time and pressure of
iiow, and the constants of the glischrometer.

The coefficient of viscosity rj may be found from the expression — •

in which K is the radius of the capillary tube and I its length, and V
the volume of the liquid of density p passing through in time t and
under pressure p. The negative term of the formula gives the mea-
sure of the correction for the kinetic energy imparted to the liquid,
as deduced by Gouette and Finkener.

With a view of tracing the influence of homology, substitution,
isomerism, molecular complexity, and, generally speaking, of changes
in the composition and constitution of chemical compounds upon
viscosity, a scheme of work was drawn up which involved the deter-
mination in absolute measure of the viscosity of between 80 and 90
liquids at all temperatures between 0° (except in cases where the
liquid solidified at that temperature) and their respective boiling
points.

1898.] on Some Recent Besults of Phjsico-Chemical Inquiry. 647

This list is as follows :—

Water HgO.

Bromine Brg.

Nitrogen peroxide NjO^ .

Paraffins and Unsaturated Fatty Hydrocarhons.

Pentaue CM^.iCM.^.QR,.

Isopentaue (CHaXCH.CHo.CHg.

Hexane CH3.(CH2X.CH3.

Isohexane .. .. (CH3).CH.(CH.,)2.CH3.

Heptane CH3.(CH-,)3.CH3.

Isobeptane (CH3).,CH.(CH.)3.CH3.

Octane CH3.(CH2),.CH3.

Trimethyl Ethylene (i8-isoamylene) (CH3),,C : CH . CH3 .

Isoprene (Peutine) CjHg.

Diallyl (Hexine) QH.^: Cll.{GB.^\.QYi -.GU,.

Iodides.

Methyl iodide CH3I.

Ethyl iodide CH3.CH0I.

Propyl iodide CH3.CH:.CH2I.

Isopropyl iodide (CHal^CHI.

Isobutyl iodide (CH3).,CH.CHJ.

Allyliodide CH, : CH.CHJ.

Bromides.

Ethyl bromide CH3.CH.,Br.

Propyl bromide CH3.CH,.CELBr.

Isopropyl bromide (CH3).,CHBr.

Isobntyl bromide (CH3)2CH.CH.Br.

Allvl bromide CH, : CH.CH,Br.

Ethylene bromide CHoBr.CHoBr.

Propylene bromide CHs.CHBr.CH^Br.

Isobutylene bromide (CH3).,CBr.CHoBr.

Acetylene bromide CHBr:CHBr.

Chlorides.

Propyl chloride CH3 . CHg . CH^Cl .

Isopropyl chloride (CH3)2CHC1.

Isobutyl chloride (CH3)2CH.CH,CL

Allyl chloride CH^: CH.CH,CI.

INIethylene chloride (Dichlorme-

thane) CH^Cl^.

Ethylene chloride CH.,C1 . CH2CI .

Ethylidene chloride CH3.CHCI2.

Chloroform (Trichlormethnne) .. CHCI3.
Carbon tetrachloride (Tetrachlor-

methane) CCI4.

Carbon dichloride (Tetrachlorethy-

lene) CCLrCCI^.

Stdphur Compounds.

Carbon bisulphide .. CSg.

Methyl sulphide (CH3)2S,

Ethyl sulphide (CH3.CH5)2S

Thiophen CH : CH.S.CH: CH

I I

2 u 2

6i8 Professor T, E. Thorpe [March 4,

Acetaldehyde and Ketones.

Acetaldehyde CH3.COH.

Dimethyl ketone CH3.CO.CH3.

Methyl ethyl ketone CH3.CH2.CO.CH3

Diethyl ketone CH3.CH2.CO.CH2.CH3.

Methyl propyl ketone CH3.(CH2)2 -00.0113. j

Acids,

Formic acid H.COOH.

Acetic acid CH3.COOH.

Propionic acid CH3.CH0.COOH.

Butyric acid CH3.(CH2)2.COOH.

Isobutyric acid (CH3)2CH.COOH.

Oxides (Anhydrides}.

Acetic anhydride (Acetyl oxide) .. (CH3.COXO.
Propionic anhydride (Propionyl
oiide) .. .. (CH3.CH2.C0),O.

Aromatic Hydrocarbons.

Benzene OyHg.

Toluene (Methyl benzene) .. .. CeHg.CHs.

Ethyl benzene C6H5.C2H5.

Ortho-xylene G6^i(^^3)z(^ •'^)-

Meta-xylene CeH,(CH3),(l : 3).

Para-xylene C6H4(GH3).,(1 : 4).

Alcohols.

Methyl alcohol CH3OH.

Ethyl alcohol CH3XH2OH.

Propyl alcohol CH3.CH2.CH,OH.

Isopropyl alcohol (CH3)2CHOH.

Butylalcohol CH3.(CH2)2.CH20H.

Isobutyl alcohol (CH3),,CH.CH20H.

Trimethyl carbinol (CH3)3COH.

Amyl alcohol (active) CH3.CH2.CH(CH3).CH20H,

Amyl alcohol (inactive) (CH3) CH.CH2.CH.,0H.

Dinietliyl ethyl carbinol . . . . (CH3)2C(OH) CH2 . CH3 .

AUylalcohol CH^ : CH . CH^OH .

Esters.

Methyl formate H.COOCH3.

Ethyl formate H.COOCH2.CH3.

Propyl formate H.COOCH2.CH2.CH3.

Mthyl acetate CH3.COOCH3.

Ethyl acetate CH3.COOCH2.CH3.

Propyl acetate CH3.COOCH2.CH2.CH3.

Methyl propionate CH3.CH2.COOCH3.

Ethyl propionate CH3.CH2.COOCH2.CH3.

Methyl butyrate CH3.CH2CH2.COOCH3.

Methyl isobuty rate (CH3)2CH . COOCH3 .

1898.] on Some Becent Results of Physico-Gliemical Inquiry. 649

Ethers.

Ethyl ether CH3.CH2.O.CH..CH3.

Methyl propyl ether CHj.O.CHj.CH^.CHs.

Ethyl propyl ether CH3.CH2.O.CH2.CH2.CH3.

Dipropyl ether CH3.CH..CH..O.CH,.CH2.0H3.

Methyl isobutyl ether CH3.0.CH2-CH(CH3)2.

Ethyl isobutyl ether CH3.CH2.O.CH2.CH(0H3)2.

In speaking of the results of the observations on these substances
the lecturer drew special attention to the case of water, more parti-
cularly as regards the efifect of temperature in altering its viscosity.
The lollowing table shows the viscosity of water in absolute measures
at temperatures between 0° and 100° C.

Temperature.

Viscosity.

Temperature.

Viscosity.

Temperature.

Viscosity.

0
0

•01778

0
35

•00720

0
70

•00406

5

•015095

40

•006535

75

•003795

10

•013025

45

•00597

80

•00356

15

•011835

50

•005475

85

'•00335

20

•010015

55

•005055

90

•003155

25

•00891

60

•00468

95

•002985

30

•007975

65

•004355

100

•00283

The results of these observations are graphically represented in
Fig. 3, in which viscosity coefficients are ordinates and temperatures
are abscisssB.

A special series of observations was made in order to ascertain
if, as inferred by Moritz, water had a maximum viscosity in the
neighbourhood of 4°, but no indication was given of any anomalous
change in the rate of variation between 0° to 8°, and the lecturer
pointed out the bearing of this fact upon the supposition that water
at low temperature is a solution of ice, richer and richer in ice as it
is more and more cooled.

The so-called anomaly of water possessing a point of maximum
density remote from its point of congelation, must be connected with
its other physical properties, and observation shows this to be the
case. Water, like all other liquids, is compressible, but whereas in
the case of all other liquids the compressibility increases with the
temperature, it is found that water at low temperature is more com-
pressible than at high temperatures. It has also been shown that
water is " anomalous " in respect to its behaviour when heated under
pressure. The degree to which it expands for a given interval of
temperature steadily increases with the pressure, and especially at
low temperatures, contrary to what is usually observed. The viscosity
of water is also affected by pressure. It has been shown by Warburg
and Sachs, and also by Rontgen, that water at ordinary temperatures

650 Professor T. E, Thorpe [Marcli d,

becomes more mobile wlieu subjected to pressure : in other words, its
viscosity is lowered by pressure. This is a very striking fact, and
so far as observation has gone it is without a parallel. Benzene,
ether, liquid carbon dioxide, all become more viscous under the

j

r

■OITOO

\

\

■nisno

\

)1300

o

\

\

\

1

o

\

!

\

<-
o

>

1-

o
o

>

\

\

1
1

\

\

\

ocnoo

\

\

\

\

\

\

cone

V

\^

^

^

^

1 1

1

■^""^

Fig. 3.— Viscosity of Water between 0° and 100°.

influence of great pressure. Now Professor Eontgen has pointed out
that thesie " anomalies " may be explained on the assumption that
water at ordinary temperatures is an aggregation of two distinct
kinds of molecules, one of which has the properties we associate with

1898.] 011 Some Recent Results of Physico-Chemical Inquiry. 651

ice. The proportionate amount of these " ice-molecules " depends,
under ordinary conditions, upon the temperature. On heating they
become fewer and fewer ; on cooling they become more numerous.
We may regard water at any particular temperature as a saturated
solution of such molecules ; when cooled below its ordinary solidifying
point it is a supersaturated solution of such molecules, and of course
behaves under such conditions like any other supersaturated solution.

Now any circumstance which effects the transformation of the
ice-molecules into the other kind of molecules should be attended by
a contraction of volume. When water is heated from 0° upwards, w^e
have two distinct volume changes — expansion of the water as such,
and the destruction or transformation of the ice-molecules with
consequent diminution of volume. Up to 4° the diminution due to
the transformation of the ice-molecules is greater than the expansion,
and the nett result is contraction. After 4° the ice-molecules
become fewer and fewer, and the degree of expansion gradually
gains upon that of the diminution in volume due to the alteration of
the ice-molecules ; and thence the degree of contraction becomes less
and less, until the nett result is an increase of volume and the water
seems to behave like any other liquid on heating. It does not,
however, follow that all the so-called ice-molecules will have dis-
appeared, even at above 8°, for the two distinct sets of molecules
may co-exist, but of course in gradually diminishing ratio as the
temperature rises.

It is easy to see how this assumption, which is but an extended
form of a very old idea, may serve to explain the " anomalies " above
referred to. Take the case of compressibility of water at low tem-
peratures. It is unnecessary to remind a Royal Institution audience
that ice, even at low temperatures, may be converted into water by
pressure ; the classical experiments of Faraday and Tyndall are
admirable illustrations of that fact. Now the more ice we thus
convert into water the greater the contraction. A given increase
of pressure at a low temiDcrature causes a i^resitev contraction than
at a higher temperature, because at the lower temperature there are
more ice-molecules to be changed. The diminution of volume under
compression is like the increase of volume by temperature, made up
of two parts, viz. (1) the real compressibility of the water ; and (2)
the diminution attending the transformation of the ice-molecules.
Probably the water-molecules, as such, behave like other molecules —
they contract under pressure, and to a gradually smaller extent as
the pressure is increased ; it is only the effect of the increased
pressure in changing the ice-molecules, with consequent diminution
of volume, that makes the apparent compressibility greater, and thus
gives rise to the " anomaly." It should follow, therefore, that at some
point of tcsmperature above the freezing point of water there should
be a minimum point of compressibility, just as there is a minimum
volume. Experiment shows that such a minimum point exists at
about 50°.

652 Professor T. E. Thorpe [March 4,

The fact, discovered by Amagat, that water under great pressure is
more expansible by heat than at ordinary pressure, may also be equally
well explained on this hypothesis. Increasing temperature, as we
have seen, works in two directions on the volume of water — but as
yet nothing is exactly known of the effect of pressure upon the volume-
change per degree of temperature of an aggregate consisting solely
of one kind of water-molecules ; but the probability is that such an
aggregate of molecules would behave like a gas. The anomaly
found by Amagat gradually disappears as the pressure is increased.
This finds its explanation in the fact that with gi*adually increasing
pressure the number of ice-molecules becomes less. Amagat also found
that the anomaly became less marked as the temperature was increased;
this also is explained by the circumstance that as the temperature
increases the number of the ice-molecules diminishes.

The same hypothesis explains the fact that under pressure the
temperature of the point of maximum density becomes lower, and
it also affords a reason for the circumstance that the freezing point of
water becomes lowered by pressure.

It has been observed that water at low temperatures becomes
colder when subjected to pressure, which may be explained by the fact
that in order to convert ice-molecules into molecules of the second
kind, heat is required, which can only be furnished by the compressed
liquid.

As regards the influence of pressure on viscosity, we have only to
assume, as analogy indicates, that the greater the number of ice-
molecules in solution the more viscous becomes the liquid. If we
add soluble matter to water, its viscosity increases. Sea water is more
viscous than pure water, and the greater the amount of salt in solu-
tion the greater becomes the viscosity. If by pressure we diminish,
for any particular temperature, the number of ice-molecules in solu-
tion, it must follow that we diminish the viscosity, which is what is
observed.

Now, in the light of Professor Eontgen's explanation, the behaviour
of water is no longer " anomalous." Its normal properties are exactly
similar to those of any other liquid. The so-called anomalies are
simply due to the circumstance that the " solid " form of water is
specifically lighter than the liquid form. The peculiar form of the
curve showing the relation between viscosity and temperature in the
case of water at low temperatures, arises from the progressive and
rapid increase of the number of the ice-molecules. In this special
particular water is not peculiar. Studies on surface energy, on vapour
pressures and densities, and on optical characters, have shown that
this hypothesis of molecular complexes is well founded, and it is
remarkable that many liquids, especially hydroxyl combinations, in
which there is reason to assume the existence of such complexes, also
exhibit curves of viscosity very similar in character to that shown by
water.

The mathematical expression of the relation of the viscosity of

1898.] on Some Becent Besults of Physico-Chemical Inquiry. 653

liquids to temperature has engaged the attention of many physicists
from the time of Poiseuille, but, on the whole, no empirical formula
reproduces the observed values better than that of Slotte, which may
be written in the shape —

rj = C/{a + ty\

In order to determine the value of the constants two values of
7], viz., rji and 773, are chosen, which correspond respectively with the
temperatures t^ and ^3 ; a third value of 77, viz. r}2, is then found from
the equation rj^ = v' rj^ rj^, ^^^ ^^^ temperature t^ corresponding with
this value 770 is found graphically, and a and n are deduced from
the equation —

1 2 - t t^

i i n =

log 771 - lonf 7)3

log (a + ^3) - log (a + <i)-

Writing the formula in the shape -q = C / (1 -{- h i)", where C is
the viscosity coefficient at 0°, the experimental results in the case
of the whole series of liquids may be accurately represented by
formulae of the Slotte type by means of the following constants.

Constants in Slotte's Formula, 77 = C/(l + h 0"-

—

C.

h.

n.

Pentane

Hexane

Heptane

Octane

Isopentane

Isohexane

Isoheptane

Isoprene ■

Amylene

Diullyl

002827
003965
005180
007025

002724
003713
004767

002600
002534
003388

•006039
•005279
•005551
•006873

008435
004777
005541

006944
005341
005780

1-7295
2-1264
2-1879
2-0290

1-2901
2-3237
2-1633

1-4433
1-7855
1-9340

Mt'thyl iodide

Ethyl iodide

Propyl iodide

Isopropyl iodide

Isobutyl iodide

Allyl iodide

005940
007 IwO
00;»372

008783
011G20

009296

007444
006352
007308

006665
009186

007933

1-4329
1-7520
1-7483

1-9161

1-6577

1-6592

Ethyl bromide

Propyl bromide

Isopropyl bromide

Isobutyl bromide

Allyl bromide

004776
006448

006044

008234

006190

007212
006421

005916

006187

006895

]-4749

1-8282

2-0166
2-1547

1-7075

654 Professor T. E. Thorpe [March 4,

Constants in Slotte's Formula, tj = C/(l + h t)" — continued.

—

C.

b.

n.

Ethylene bromide

Propyl, ne bromide

Isobutylene bromide

Acetylene bromide

•024579
•023005
•033209

•012307

•012375
•011267
•013227

•008905

r6222
1-7075

1-7988

1-5032

Bromine

•012535

•00S935

1-4077

Pro])yl cliloride

Isopropyl chloride

Isobutyl chloride

AUyl chloride

•004319

•004012
•005842

•004059

•004917

•007185
•007048

•006366

2-2453

1-5819
1 • 8706

1-7459

Ethylene chloride

Ethylidene chloride

Mttl.ylene chloride

Chloroform

Carbon tetrachloride

Carbon dichloride

•011269

•00G205

•005357
•007006
•0134GG

•01139

•009933
•007575

•007759
•006316
•010521

•007925

1-6640
1-6761

1^4408
1-8196
1^7121

1-6325

Carbon bisulphide

•004294

•005021

1 • 6328

Methyl sulphide

Ethyl sulphide

•003538
•005589

•005871
•00b705

1-6981
1-8175

Thiophen

•008708

•009445

1-6078

Dimethyl ketone

Methyl etliyl ketone . . . .
Methyl propyl ketone ..
Diethj 1 ketone

•003949
•005383
•006464
•005919

•004783
•007177
•007259
•006818

2-2244

1-7895
1-8248
1-8626

Acetaldehyde

•002671

•003495

2-7550

Formic acid

Acetic acid

Propionic acid

Butyric acid

Isobutyric acid

•029280
•01G867
•015199
•022747

•018872

•016723

•008912
•009130
•010586

•009557

1-7161
2-0491
1-8840
l-i)920

2-0059

Acetic anhydride

Propionic anhydride

•012416
•016071

•010298
•011763

1-6851
1-7049

Ethyl ether

•002864

•007332

1-4644

1898.] on Some Recent Results of Physico-Chemical Inquiry. 655
Constants in Slotte's Formula, tj = C/(l + & 0" — continued.

—

C.

&.

n.

Benzene

Toluene

Ethyl benzene

Ortho-xylene

Meta-xyleiie

Para-xylene

•009055

• 0076S4
•008745

•011029
•008019
•008457

•011963
•008850
•008218

•010379
•008646
•008494

P5554
1-6522
1-7616

1-6386
1-6400
1^7326

Water—

0°to 8°

0° to 100°

•017793
•017944

•017208
•023121

1-9944
1-5423

Methyl alcohol

Ethyl alcohol

Propyl alcohol . .
liutyl nlcohol —

0°to 52°

52° to 114°

Isopropvl alcohol —

0°to40°

40° to 78°

Isobutvl alcoliol —

0° to 38°

38° to 75°

75° to 105°

Inactive amyl alcohol —

0°to 40°

40° to 80°

80° to 128°

Active amyl alcohol —

0°to 35°

35° to 73°

73°tol2i°

Trimethyl carbinol —

20° to 50°

50° to 77°

Dimethyl ethyl carbinol —

o°to27° .. .. :.

27° to 63°

63° to 95°

AUyl alcohol

•008083
•017753
•038610

•051986
■056959

•045588
•048651

•080547
•085365
•094725

•085358
•093782
•152470

•111716
•124788
• 147676

•135060
1^755458

•142538
•154021
•131901

•021736

•006100
•004770
•007366

•007194
•010869

•007057
•011593

•010840
•011527
•015888

'008488
•012520
•026540

•009851
•015463
•127583

•128156

•196967

•020868
•027019
•026082

•009139

2-6793
4-3731
3-9188

4-2452
3-2150

4 •9635
3-4079

3-6978
3-6708
3-0537

4-3249
3-3395
2-4618

4-3736
3-2542
2 0050

1-8232
2-0143

3-2080
2 7578
2-6610

2-7925

Nitrogen peroxide

•005267

•007098

1-7319

Methyl formate

Ethyl formate

Propyl formate

•001301

•005048
•006679

•014655
•007197
•007179

0-8325
1-7006
1-9154

656 Professor T. E. Thorpe [March 4,

Constants in Slotte's Formula tj = C/(l + 6 ty — continued.

Methyl acetate
Etliyl acetate ..
Propyl acetate . .
Methyl propionate ..
Ethyl propionate
Methyl butyrate
Methyl isobutyrate ..

Diethyl ether ..
Methyl propyl ether
Ethyl propyl ether . .
Diproj)yl etlier
Methyl isobutyl ether
Ethyl isobutN 1 ether

•004781

• 005783

• 007706
•005816
•006928
•007587
•006720

•002864
•003077
•003969
•005401
•003813
•004826

6.

006472
007:584
007983
006820
007468
008081
007144

007332
006809
005454
006740
005737
0C6549

8636
8268
8972
8972
8914
8375
9405

1-4644
l-f863
2-1454
1-9734
2 0109
1-9733

Slotto's formula gives the best results in the case of observed
viscosity curves in which tlie slope varies but little with the tempera-
ture. As regards the relation between the chemical nature of the
substances and the magnitude of their temperature coefficients, it is
evident that —

(a) From the mode in which the constants n and h are derived,
their individual values cannot be expected to be simply related to
chemical nature.

(b) For the majority of the liquids the formula —

V = C/(l+ lit + yr-)

obtained from Slotto's formula by neglecting terms in the denominator
involving higher powers of t than <^, closely expresses the eflfect of
temperature on viscosity, and in the formula the magnitudes of the
coefficients f3 and r) are found to be definitely related to the molecular
weight and constitution of the substances, except in the case of liquids
which, like water and the alcohols, contain molecular aggregate.

In order to obtain quantitative relationships between viscosity
and chemical nature, and to compare one group of substances with
another, it is necessary to fix upon particular temperatures, and to
obtain and compare the values corresponding with those tempera-
tures. The first point to decide was at what temperatures viscosities
should be compared. Inasmuch as the viscosity curves, even in the
same family of substances, cross one another, it is obvious that quanti-
tative relationships obtained at any single temperature of comparison,
as has usually been done, can have no pretensions to generality.
Following the method of Kopp, temperature of the boiling point may
be considered as a comparable temperature, or we may adopt the

1898.] on Some Becent Besults of Physico-Chemical Inquiry. 657

method indicated by Van der Waals ; or, lastly, we may compare the
viscosity values at the temperatures of equal slope, or at temperatures
at which drj / dt is the same for the different liquids — that is, points
at which temperature is exercising the same effect on viscosity.

Now, no matter which of these modes of comparison be instituted,
definite general relations are apparent. Thus, if we compare the
viscosity coefficients at the boiling points, it is found that as a
homologous series is ascended the coefficients, as a rule, diminish.
Of corresponding compounds, the one having the highest theoretical
molecular has the highest coefficient. Normal propyl compounds
have higher values than allyl compounds, and an iso-compound has a
larger coefficient than a normal compound. In the case of other
metameric substances, branching of the atomic chain and the sym-
metry of the molecule influence the magnitudes of the coefficients,
the ortho-position in the case of aromatic compounds having a more
marked effect than either the meta- or para-positions. There are,
however, certain significant exceptions to the universality of these
rules, but these are in all probability dependent upon differences in
molecular complexity, as there is independent reason for believing
that the anomalous liquids contain molecular aggregates. Very similar,
although less definite, relationships are obtained at corresponding
temperatures obtained by the method of Van der Waals, and these are
still more obvious when the comparisons are made at temperatures of
equal slope.

The attempt has been to ascertain if molecular viscosity can be
expressed as the sum of partial effects which may be ascribed to the
atoms and to the modes of atom linkage which occur in the molecule,
and it has been found possible to obtain values for particular ele-
ments and groups, and to trace the special influence of the iso-
grouping, of ring grouping, and of double linkage, upon the viscosity
of a liquid in such manner as to obtain a very fair agreement between
the observed and calculated value. Fundamental viscosity constants
have thus been obtained for the various elements, and it fs possible
to assign a quantitative value to specific differences in molecular
arrangement. Thus the fundamental viscosity constants at tempera-
tures of equal slope may, for a particular slope, be expressed as
follows : —

Fundamental Viscosity Constants.

Hydrogen

Carbon

Hydroxyl-oxygen C — O — H

Ether-oxygen .. .. -.. .. C— O— C
Carbonyl-oxygen C = 0

H

C

o

o<

II

o

44-5

31
166

58
198

658

Professor T, E. Thorpe

[March i,

Fundamental Viscosity Constants — continued.

Sulphur C— S— C

Chlorine (in monochlori(les)

Chlorine (in dichlorides)

Bromine (in raonobromides)

Bromine (in dibromides)

Iodine

Iso grouping

Double linkage

Ring-grouping

s

246

CI

256

cr

244

Br

372

Br'

361

I

499

<

- 21

( = )

48

@

244

The following tables show the numbers calculated by means of
these constants, together with those actually observed in a number of
cases : —

—

Observed.

Calculated.

DiffLi-euce per cent.

Pentane

Hexane

Heptuno

Octane

Isopentane

Isohexane

Isoheptane

Isoprene

Diallyl

687

818

931

1035

663

799
908

620

728

689

809

929

1049

668
788
908

607
729

-0-3
1-1
0-2

-1-3

-0-7
1-4
0-0

21
-0-1

Methyl iodide

Ethyl iodide

Propyl iodide

Isopropyl iodide

Isobutyl iodide

Allyl iodide

638
778
903

878

1010

864

664

784
904

883

1003

866

-4-0
-0-8
-0-1

-0-6

0-7

-0-2

Ethyl bromide

Propyl bromide

Isopropyl bromide

Isobutyl bromide

663
774

750

877

657

777

756
876

0-9
-0-4

-0-8
0 1

1898.] on Some Recent jResidts of Physico-Chemicallnquiry. 659

—

Observed.

Calculated.

Difference per cent.

Allyl bromide

Ethylpne bromide

Propylene bromide

Isobutylene bromide
Acetylene bromide

734

973

1068

1171

932

739

962

1082

1181

921

-0-7

1-1

-1 3

-0 9

1-2

Propyl chloride

Isopropyl cliloride

Isobutyl chloride

Allyl chloride

Ethylene chloride

Methylene chloride

658

6U
760

617

737
600

661

640

760

623

728
600

-0-4

0-6
00

-1 = 0

1-2

0-0

Methyl sulphide

Ethyl sulphide

578
812

575
815

0-5
-0-3

Dimethyl ketone

Methyl ethyl ketone
Methyl propyl ketone ..
Diethyl ketone

572
671
796

785

558
678
798
798

2-4
-1-0
-0-2
-1-6

Acetaldehyde ,

448

438

2-2

Formic acid

Acetic acid

Propionic acid

Butyric acid

Isobutyric acid

456
593
7+2
842

843

484
604
724
844

823

-6-1

-1-8

2-4

-0-2

2-4

Acetic anhydride

Propionic anhydride

838
1036

845
1085

-0-8
-4-7

Ethyl ether

635

627

1-3

Benzene

Toluene

Ethyl benzene

Ortho-xylene

Meta-xylene ..
Para-xylene

688
821
939

954
939
923

697
814
934

934
934
934

^1-3

0-8
0-5

21
0-5

-1-2

These general results are, it should be stated, independent of the
magnitude of the slope : no matter what particular value be selected,
the relations are made obvious. Of course, in the actual comparison,
such a value of the slope was selected as would comj)rehend the
greatest number of observed cases.

In conclusion it may be pointed out that a comprehensive view of
the physico-chemical relationships of a series of substances can only

660 Becent Besults of Physlco-Chemical Inquiry. [March 4,

be obtained by studying the variation of the physical property over as
wide a range of temperature as possible ; that the graphical or alge-
braical representation of the results so obtained will indicate whether
particular members of a series are exceptional in behaviour as com-
pared with their congeners ; and if such exceptional behaviour occurs,
it may be detected either in the viscosity-magnitude or the temperature,
no matter whether we use the boiling point, a corresponding tempera-
ture, or a temperature of equal slope as the condition of comparison.

[T. E. T.]

GENERAL MONTHLY MEETING.

Monday, March 7, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.R.S.

Treasurer and Vice-President, in the Chair.

Miss Cecilia Ash,

Mrs. Henry C. A. Baynes,

Miss Mary E. Bevington,

Tlie Hon. Edith M. Boscawen,

Miss Alice M. Burton,

The Rev. J. J. Coxhead, M.A.

Alfred Charles Cronin, Esq.

Ralph Collingwood Forster, Esq.

William Garnett, Esq. M.A. D.O.L.

Herbert Godsal, Esq.

Alexander H. Goschen, Esq.

Major-General Coleridge Grove, C.B.

Arthur Humbert, Esq,

Josei^h Kincaid, Esq. M.A. M. Inst. C.E.

Captain William N. Lister,

Lazare M. Lowenstein, Esq.

George Wharton Marriott, Esq.

Mrs. E. R. Mtrtou,

Thomas MiddJemore, Esq.

Bertram Savile Ogle, Esq. J. P.

Paris Eugene Singer, Esq.

(ieorge Paul Taylor, Esq.

John Thornton, Esq.

Sir Arthur Si^eiicer Wells, Bart.

were elected Members of the Royal Institution.

1898.] General Monthly fleeting. 661

The Special Thanks of the Members were returned for the follow-
ing Donation to the Fund for the Promotion of Experimental Research
at Low Temperatures ; —

Mr. Hugh Leonard £50

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

The Meteorological 0/f?ce— Meteorological Observations at Stations of the Second
Order for 1894. ' 4to. 1897.
Hourly Means, 1894. 4to. 1897.

Rainfall Tables of the British Islands. 1866-90. 8vo. 1897.
Quarterly Current Charts for the Pacific Ocean, fol. 1897.
Accademia dei Lincei, Reale, Roma — Classe di Scienze Fisiche, Matematiche e
Naturali. Atti, Serie Quinta : Rendiconti. 2' Semestre, Vol. VI. Fasc. 11,
12, Classe di Scienze Morali, &c. lo Semestre, Serie Quinta, Vol Vll'
Fasc. 2, 3. 8vo. 1898.
American Academy of Arts and Sciences — Proceedings, New Series, Vol. XXIII

Nos 5-8. 8vo. 1897.
American Geographical Society— EnWeim, Vol. XXIX. No. 4. 8vo. 1897.
Adronomical Society, Royal — Monthly Notices, Vol. LVIII. No. .S. 8vo. 1898.
Asiatic Society, Royal (Bombay Branch) — Journal, Vol. XIX. No. 53. 8vo. 1897.
Ball, Sir Robert S. F.R.S. (the Author)— Vhe Twelfth and Concluding Memoir on
the Theory of Screws, Nvith a Summary. (Roy. Irish Acad. Trans. Reprint )
4to. 1898.
Rankers, Institute o/— Journal, Vol. XIX. Part 2. 8vo. 1898.
Berlin, Royal Frustian Academy of Sciences — Sitzungsberichtis 1897, Nos. 40-53.

8vo.
Boston Public Lrtror?/ -Monthly Bulletin, Vol. III. No. 2. 8vo. 1898.
Botanic Society, Royal — Quarterly Record, Nos. 71, 72. 8vo. 1897.
British Architects, Royal Institute of — Journal, 3rd Series, Vol. V. Nos. 7, 8. 4to

1898.
British Astronomical Association — Memoirs, Vol. VI, Part 3. 8vo. 1898

Journal, Vol, VIII. No. 4. 8vo. 1898.
Camera r/M?>— Journal fur Jan. Feb. 1898. 8vo.

Canada, Meteorological Office of — Report of the Meteorological Service of Canada
for 1890, By^R, F, Stupart, 8vo, 1895.
Report of the Meteorological Service of Canada for 1895, By R. F, Ptupart
4to, 1897.
Chemical Indudry, Society of — Journal, Vol. XVII. No. 1. 8vo, 1898,
Chemical Society — Journal for Feb, 1898, 8vo.

Proceedings, Nos. 188, 189, 8vo. 1897.
Chicago, Field. Columbian Mnseum — Publications, Nos. 22, 24. 8vo. 1897.
Clinical Society of London — Index to Transactions, Vols. I,-XXX. 8vo. 1898,
Cracovie, Academic des Sciences — Bulletin, 1898, No. 1, 8vo,
Crawford and Balcarres, The Earl of, K.T. M.R.L—
Bibliotheca Lindesiana —
Hand-list of Oriental MSS, : Arabic, Persian, Turkish. (Privatelv printed.)
8vo. 1898,
Editors — American Journal of Science for Feb. 1898. 8vo.
Analyst for Feb. 1898. 8vo.

Anthony's Photographic Bulletin for Feb. 1898. 8vo.
Astrn-phvfcical Journal for Jan. 1898, 8vo,
Athenseum for Feb, 1898, 4to.
Author for Feb. 1898. 8vo.
Bimetallist for Feb. 1898. 8vo,
Vol. XV. (No. 92.) 2 x

662 General Monthly Meeting. [Marcli 7,

Editors — continued.

Brewers' Journal for Feb, 1898. 8vo.
Chemical News for Feb. 1898. 4to.
Chemist and Druajgist for Feb. 1898. 8vo.
Education for Feb. 1898.
Electrical Engineer for Feb. 1898. fol.
Electrical Engineering for Feb. 1898. 8vo.
Electrical Review for Feb. 1898. 8vo.
Electricity for Feb. 1898. 8vo.
Engineer for Feb. 1898. fcl.
Engineering for Feb. 1898. fol.
Homoeopathic Review for Feb. 1898. 8vo.
Horological Journal for Feb. 1898. 8vo.
Industries and Iron for Feb. 1898. fcl.
Invention for Feb. 1898.

Journal of State Medicine for Feb. 1898. 8vo.
Law Journal for Feb. 1898. 8vo.
Life-Boat Journal for Feb. 1898. 8vo.
Lightning for Feb. 1898. 8vo.
Machinery ]\Tarket for Feb. 1898. 8vo.
, Nature for Feb. 1898. 4to.
New Church Magazine for Feb. 1898. 8vo.
Photographic News for Feb. 1898. 8vo.
Pliysical Review for Jan. 1898. 8vo.
Public Health Engineer for Feb. 1898. 8vo.
Science Siftings for Feb. 1898.
Travel for Feb. 1898. 8vo.
Tropi.-al Agriculturi.4 for Feb. 1898.
Zoophilist, for Feb. 1S98. 4to.
Electrical Engineers, Inditution o/"— Journal, Vol. XXVI. No. 131. 8vo. 1898.
Fleming, Professor J. A. MA. F.R S. M.R.L {the Author) — Magnets and Electric

Currents. 8vo. 1898.
Florence, Bihlioteca Nazionale Ceufm/e -Bolletino, Nos. 291, 292. 8vo. 1897.
Franldin Institute— So\\xnsi\ for Feb. 1898. 8vo.
Geographical Society, i?o?/aZ— Geographical Journal for Feb. 1898. 8vo.

Year Book and Record. (First Issue.) 8vo. 1898.
Geological Society — Quarterly Journal, No. 213. 8vo. 1898.

Geological Literature added to the Lilirary during 1897. 8vo. 1898.
Imperial Institute— Im-per'ml Institute Journal for Feb. 1898.
Iron and Steel Inxtitute -Journal, 1897, No. 2. 8vo. 1898.
Jordan, W. L. Esq. M.R.I (the Author)— The Spinning Top. fol (MS.)
Louis, B. A. Esq. F.I.C. (the Author) — The Iron Industry of Hungary. 8vo.

1898.
Manchester Geological /S'o''refi'/— Transactions, Vol. XXV. Part 12. 8a^o. 1898.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Vol.

XLII. Part 1. 8vo. 18H7-98.
Manchf:ster Museum, Owens College — Museum Handbook. Catalogue of Shells,

Parts 2, 3. Svo. 1898.
31 assachu setts Institute of Technology — Technology Quarterly, Vol. X. No. 4. 8vo.

1897.
Microscopical Society, Royal — Journal, 1898, Part 1. Svo.
Mitchell and Co. Messrs. C. — New.<paper Press Directory, 1898. Svo.
Aeio South Wales, The Agent-General for — Wealth and Progress of New South

Wales, 1895-96, Vol. IL Svo. 1897.
Odoutological Society — Transactions, Vol. XXX. No. 4. Svo. 1898.
Paris, Societe Franc^aise de Physique— BuUetiu, Nos. 109, 110. Svo. 1898.
Pharmaceutical Society of Great Britain — Journal for Feb. 1898. Svo.
Photographic Society, Royal — List of Members, 1898. Svo.
Photographic Journal for Jan. 1898. Svo.

1898.] General Monthly Meeting. 663

Queensland, The Agent-General for— Annah of the Queensland Museum, No. 1.

8vo. 1891.
Eadd/fe Library, Oxford University, Museum — Catalogue of Books added to the

Library during 1897. 4to. 1898.
Rome, Ministry of FuhJic TForA's— Giornale del Genio Civile, 1897, Fasc. 8-10.

8vo. 1897. * And Designi. fol.
Hoyal Society of London — Pliilosophical Transactions, Ser. A. Vol. CXC. Nos. 209,

210. 4to. 1898.
Proceedings, No. 384. 8vo. 1897.
Saxon Society of Sciences, Royal —
Mathematisch- Physische Classe —

Abhandlungen, Band XXIV. Nos. 2, 3. 8vo. 1898.
Pb iloJogisch-Historische Classe —

Bericl.te, 1897, No. 2. 8vo. 1898.
Selborne Society — Nature Notes for Feb. 1898. 8vo.
Soc'ety of ^r^s— Journal for Feb. 1898. 8vo.
Tacchini, Prof. P. Hon. Mem. R.L {the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXVII. Disp. 1. fol. 1898.
Taylor, Sedley, Esq. M.A. (the Author) — A System of Si-ht-Singing from the

established musical Notation based on the piinciple of Tonic Relation. 8vo.

1890.
United Service Institution, Royal — Journal for Feb. 1898. 8vo.
United Slates Department of Agriculture — Experiment Station Record, Vol. IX.

No. .5. 8vo. 1898.
United States Patent O^^ce— Official Gazette, Vol. LXXXI. Nos. 7-13; Vol.

LXXXII. Nos. 1-8. 8vo. 1897-98.
U.S. Army, Surgeon-General's Office — Index Catul gue of tlie Library of the

Surgeon-General's Office, St cond Serie.-, A'ol. II. 8vo. 1897.
Vienna, hnperial Geological Institute — Vcrliandlung( n, 1897, Nos. 17, 18. 8vo,
Vizagapatam, G. V. Juggarow Observatory — Report. 1896. 8vo. 1897.
Walsh, D. Esq. M.D. (tlie Author) — The Rontgen Rays in IMedical Work, with

Introduction on Electrical Apparatus and Methods. By J. E. Greenhill.

8vo. 1897.
Wright, J. and Co. 3Iessrs. (the Publishers) — The Medical Annual for 1898. 8vo.
Yorkshire Arehseological Society — Yorkshire Arch geological Journal, Part 56.

8vo. 1898.
Zoological Society of Lo?K?(;n— Transactions, Vol. XIV. Part 5. 4t.o. 1898.

2 X

664 Mr. Walter Frewen Lord [Marcli 11,

WEEKLY EVENING MEETING,

Friday, Marcli 11, 1898.

Sir Fhederick Bramwell, Bart. D.O.L. LL.D. F.R.S.
Honorary Secretary and Vice-President, in the Chair.

Walter Frewen Lord, Esq.
"MarJced Unexplored.'^

The small area of unexplored history that I shall ask your leave to
open up this evening is that curious backwater of Mediterranean
history which I have called Murat's dream. It was an early attempt
to unify Italy, and was defeated by Lord William Bentinck and Louis
Philippe (afterwards King of the French) when Due d'Orleans.

In order to facilitate my exposition of this highly comj^licated
period I will ask your attention to these four maps. The first repre-
sents Murat's dream ; the second represents what actually happened
to Italy when that dream ceased to be even an asj^iration ; the third
represents Italy at tlie present moment : I will speak of the fourth
map presently. As regards the first map I need hardly remind you
that after the battle of Austerlitz the ancient kingdom of tho Two
Sicilies was conferred upon Joseph Bonaparte by his brother Napo-
leon. This was a simple operation in so far as the mainland
dominions were concerned ; but Sicily, being an island, and pro-
tected by the British fleet, was beyond Napoleon's reach, and never
passed out of the hands of the Neaj^olitan Bourbons. Joseph, when
presented to the throne of Spain, was succeeded by Joachim IMurat,
Napoleon's brother-in-law, and at the time that our story opens Murat
was de facto King of Naples. To that kingdom he had recently added
the States of the Church. He w^as in military occupation of the
Grand Duchy of Tuscany. His brother-in-law, Prince Borghese —
not a warlike or an ambitious person — was in occupation of Piedmont ;
the King of Sardinia having retired to the island from which he took
his title. Sardinia was at this epoch, all that remained to the
present Eoyal House of Italy. It is obvious that this is the largest
homogeneous dominion actually and potentially (for there would
have been no difficulty about Lucca, Parma and Modena) ever carved
out in Italy since the fall of the Roman Empire until the year 1861.
Murat proposed to make this a permanent settlement ; leaving
Ferdinand of Bourbon in Sicily, the House of Savoy in Sardinia,
England in Corsica, and Austria in her dominions of Northern Italy.
England and Austria assented to this plan ; and before we come to

1898.] on ''Marked Unexplored:' 665

consider how a scheme so powerfully supported was not carried out,
we must first ask why F>iigland and Austria (neither power yielding
to the other in hatred of Napoleon and his family) came to sanction it.

It was a question of military expediency. On the 28th of October,
1813, the Allied Armies halted on the right bank of the Khine. But
they durst pursue Napoleon no further ; and waited for their left
wing to swing round and take Napoleon in the rear. But their left
wing could not swing round. Marshal Bellegarde, commanding the
Austrian army, refused to move a man under existing circumstances.
He openly stated that the Allies must come to a compromise. Some-
how or other Murat must be detached from Napoleon's cause in order
to break up the deadlock in Italy.

The fourth map. The deadlock in Italy was caused in this way.
Eugene Beauharnais' army of 40,000 men practically held in check
the Austrian army of 70,000, because Bellegarde was compelled to
detach an army corps to watch Murat, who in his turn could do
nothing because he was between Bellegarde and Bentinck. If Murat
could only be won over to the cause of the Allies, they would
command 120,000 men to Beauharnais' 40,000, and France could
easily be invaded by way of the Riviera. Murat deserted the
Emperor, and threw in his cause with the Allies ; his price being his
own definite and ofiieial recognition as King of Naples, while he on
his part consented to recognise Ferdinand as King of Sicily.

Murat's conduct has been variously described. We shall see,
presently, what Bentinck thought of it. M. Thiers records that
Napoleon said that he had made a great mistake in making Murat
a king, as he now thought only of his own kingdom and France
came second. Murat himself stated that ho was now an Italian,
and thought only of the interest of Italy. The Austrians thought
that Muiat meant to make the most for himself out of the situation,
that his defection might be useful to them, and that, further, Murat
had excellent grounds for dissatisfaction with his brother-in-law's
interfering and imperious behaviour.

Be that as it may, Murat quitted the Grand Army after a violent
quarrel with the Emperor, and betook himself to Italy with the object
of unifying it in the manner I have briefly sketched.

At this time Lord William Bentinck was Commander-in-Chief and
Ambassador Extraordinary in Sicily. He commanded about 30,000
men. Bellegarde was the Austrian Commander-in-Chief, Count Mier
was the Austrian Charge d' Affaires, and Count Neipperg was the
Austrian Ambassador Extraordinary charged with the execution of
the Treaty of Alliance and Recognition. Lord William Bentinck
was charged with the same duty on the part of England.

Lord William Bentinck received his instructions early in January
1814 from Lord Castlereagh. This is the temper in which he
received them. "I was always afraid that Count Neipperg would
be overreached by that Italian court " (meaning Naples). *' The
conditions of this treaty are altogether impolitic, inexpedient and

666 Mr. Walter Frcwen Lord [Marcb 11,

unnecessary. Upon Murat no reliance can ever be placed. But this
treaty creates not only a rival but a master perhaps in Italy " (which
is exactly what it was intended to do). "When the Viceroy"
(Eugene Beauharnais) '• is driven back to the Alps the Italians will
certainly gravitate towards Murat. But if the British protection and
assistance had happened co be within their reach, that srreat floating
force would certainly have ranged under their standard. The nntioual
energy would then have been roused, like Spain and Germany, in
honour of national independence, and this great people, instead of
being the instrument of the ambitions of one military tyrant or
another, or, as formerly, the despicable slaves of a set of miserable
petty princes, they would have become a powerful barrier both
against Austria and France, and the peace and happiuess of the world
would receive a great additional security — but I fear the hour is
gone by. It is lamentable also to see superior rewards showered
upon a man whose whole life has been crime " (this means Murat),
" who has been the intimate and active j)artner of all Bonaparte's
wickedness, and whose last act of treachery to his benefactor has been
the result of necessitv. This treaty is a sad violation of all j^ubl.e
and private principle."

I am sure that you will be grateful to me when I say that that is
the only one of Lord William Bentinck's despatches that I shall read
to you.

1 apprehend that it is open to an ambassador to have his private
opinion on his instructions ; but when his views are of this violent
character there are only two courses that he can pursue with self-
respect and honesty : the first is, do what Benjamin Keene did when he
wfis directed to surrender Gibraltar to Spain. He rent his garments
in rage and mortification — and then did what he was told. The
second is to do what Gilbert Elliot did when he was ordered to carry
o:i the government of Corsica under impossible conditions. He
asked that he might be rej)laced immediately ; but if any value was
placed upon his services, the conditions of his charge must be altered
as he indicated. Bentinck took neither of these courses. He used
his instructions to defeat the plans of the Cabinet. Thus in sending
Mr. Graham, his private secretary, to Naples, ostensibly to sign the
treaty, tbe terms of which had been already settled between England
and Austria, he directed him to use his intimacy with the Neapolitan
court, in order to obtain a passport to the Austrian headquarters.
Such a passport was courteously granted to him, of course under the
impression that it was being granted to a man who was at work on
the treaty. Not at all. " You will use the armistice as a means of
getting to the headquarters and informing the authorities in secrecy
that I am about to occupy Corsica with 10,000 fout, 400 horse and
30 guns," and to concert this landing with them.

In due course the King of Naples' envoys. Colonel Barthemy, an
A.D.C. of King Joachim, and Baron d'Aspern of Count Neipperg's
suite, arrived at Palermo to do their work. Bentinck ^' relused to

1889.] on ''MarJced Unexplored:' 667

compromise himself in any manner." " Eefused to comj)romise
himself," by obeying the orders of his sovereign.

Mr. Graham, on our side, arrived at Naples on the 5th of January,
was conveyed in a royal carriage to the Due de Gallo's, where he met
Count Noipperg and Menz. They naturally supposed that Graham
had come to sign the treaty on Bentinck's behalf; but when it was
presented to him, Graham said that he had no instructions. The
Austrians stared at him, and naturally wondered what in that case he
had come to Naples for. They did not suspect Bentinck's perfidy.

After a few days of dining and feting, Mr. Graham had another
interview with Count Neipperg. Count Neipperg was completely
bewildered at (I'raLam's attitude. The question, he said, had been
settled by Lord Aberdeen and Prince Metternich, acting under the
ordi^rsof their soveieigns, and neither he nor Lord William Bentinck,
still less Mr. Graham, could pretend to any discretion in the matter.
They were merely agents. Graham was a loyal private secretary, and
struggled hard in an impossible situation. At length he dro])i)ed a
word in favour of King Ferdinand, and Neipperg flashed out at him,
" It was absurd," he said, " that a useless monarch should stand in the
way of the peace of Europe ; and Austria," he went od, was quite
prepared to lorce Ferdinand to renounce Naples if he did not do so
of free will.

"A u-rcless monarch" is a remarkable expression v\lien applied
to a Bourbon sovereign married to an Austrian archduchess, and
applied, too, by the ambassador of the Austrian Emperor. I thipk
it shows how determined Austria was to establish the throne of
Murat. For the rest the epithet is entirely in place. Never was
there a more useless monarch than Ferdinand of Naples.

Neipperg summoned up the resolve of his court in these words :
*' Wherever we can find a soldier to oppose to the French armies, we
shall buy him at any cost," and " King Joachim must now have a
better military frontier." That is a well-known diplomatic phrase,
and, of course, implied a large addition to his territory. Thus the
intentions of Austria were manifest. Murat, on his side, by the
mouth of the Luke of Campochiaro, stated plainly that his deter-
mination was to be the leader of United Italy; that in that cause
lie had no desire for any ally except England : with himself on land
and England in alliance at sea, he said, United Italy was a certainty.
He was so well aware, he added, of the hopelessness of ever rivalling
Euglaud at sea, that he was ready to hand over all his ships to
England at once. So near as this was Italy to being unified in the
year 18 U.

Giaham, on his part, would say nothing definite, listened to
everyone, reported to Bentinck, and even went so far in dissimulation
as to arrange an imaginary campaign, with King Joachim command-
ing the centre of the Allied Army, and having Bellegarde on his right
wing and Bentinck on his left. So loyal was lie in a disloyal cause.
He then extracted the passport for the Neapolitan Ministry for

668 Mr. Walter Frewen Lord [March 11,

Foreign Affairs, and mule Lis way to Geneva, the headquarters of
the Allies, ostensibly t > forward tlie plans of Murat, really to thwart
them. Thus Bentinck had managed to waste a fortnight, aud England
was still unpledged.

On the 7th of January, i814, tlie treaty between Austria aiid
Naples was signed by the Duke of Gallo for Kiug Joachim and by
Adam, Count Neippcrg, fov the Emperor. The secret articles bound
Austria to obtain the rec ignition of Kiug Joachim by England, and
to compel King FerHnand of Sicily (by force if necessary) to
acknowledge that Naples had passed away from him for ever. The
next day Count Neipperg wrote to Bentinck and remonstrated at the
delay. He urged all the arguments that he could think of (and what
a strange notion of Knglish discipline he must have formed when he
found that he had to coax a lieutenant-general into obeying his
sovereign's orders), and wound up by reminding Bentinck of the
very serious nature of the Euroj)ean cris's. If it turned out badly,
he urged, the world would hold Neipperg and Bentinck to be
responsible.

Three weeks later, on the 30tli of January, Bentinck gave some
signs of life. He wrote a despatch to Castlereagh, complaining with-
out the slightest grounds, so far as I have been able to discover, of an
" apparent want of good faith " on the part of Austria ; and adding,
" I am aware that Murat wishes to make every possible parade and
demonstration of a good understanding with Great Britain, as the
most effectual means of quieting the discontent existing both among his
subjects and his army." Note the discourteous expression " Murat,"
instead of the " King of Naples." This is only an exaggerated
instance of Bentinck's habitual attitude towards those with whom
he was dealing. You would gather from his letters that he was the
only honest man in Italy. " Jn point of fair dealing, I consider
Prince Metternich and King Mxirat to be nearly on a level."

Having pushed sheer inertia so far as it was possible to push it
without running the risk of being recalled, Bentinck now proceeded
in a leisurely way to take action ; with how much intention that it
should be effective we may suppose when he writes, " I feel consider-
able embarrassment in what manner I should act." Considerable
embarrassment ! With his instructions on the table in front of him !
He began by saying that he could not possibly go to Naples except
incognito. AVhat an extraordinary condition for an ambassador to
make ; and added that he could not set foot in Naples until he was
definitely assured on that point, as he was in the embarrassing situa-
tion of being the ambassador of a government that so far had not
recognised the King of Naples. When the whole point of his
instructions was to recognise him, and that immediately !

What adds a touch of grim humour to the situation, is Bentinck's
habit of writing offtcially of his " straightforwardness," his " upright-
ness," on one occasion of his " known frankness."

At last, on the 6th of February, this man of known frankness

1898] on" Marked Uncxyloreci:' G69

made his way to Naples and wrote to Lord Castlereagh that the Due
de Gallo and Count Neipperg were most pressing for him to sign,
but that he would not, because no reliance was to be placed upon
Murat. Bowever, he went so far as to sign on armistice, which was
all the Allies could get out of him. He then returned to Palermo,
and took up the routine of administration there, leaving the Austrians
and Neapolitans gazing at each other in mute amazement at finding
so irresponsible a person in so responsible a situation.

In Palermo he found a despatch from Lord Castlereagh, directing
him to inform the Crown Prince that it wus out of the question for
the Poyal family of Sicily to hope any more for the restoration of
Naples, but that Great Britain would see that they were properly
compensated. The Crown Prince was invited to chooge, in order of
preference, whatever addition to Siciiy he would like instead of
Naples. He might choose from this list, Poland, Lombardy, Saxony,
Sardinia, Corsica, the Ionian Islands, or (oddly enough) the West
Indian Islands, 'i bus the intentions of England were no less plain
than those of Austria.

Bentinck seems by this time to have felt that something more was
expected of him than writing declamatory despatches, abusing alike
the cabinet of the Prince Repent, the Austrians and the French.
So he made a great display of zeal and energy, resulting (as such
displays mostly do) in nothing. He sailed from Palermo on the
28th of February, reached Naples on the 2nd of March and made his
way by land to Leghorn, which place he reached on the 8th. Here
Filangieri, a messenger from King Joachim, reached him, but he
would not compromise himself, hurried on to Reggio, which he
reached on the loth, and ultimately made his way to Verona by the
22nd. Let me remind you that this is just three months after oi'ders
for the immediate conclusion of the treaty with Murat had been
issued. On the road he favoured the cabinet with some comments
on their policy. " All parties," he wrote, " agree in one view, viz. that
of augmenting as much as possible Murat's power, and of uniting
Italy under his standard." " A stand sbould be made at once
against these views of ambition." Verona was the Austrian head-
quarters. Here Bentinck met Bellegarde, and, after his usual fashion,
made a violent attack upon his probity. " I found the Marshal
anxious to believe to be true that which he knew to be false." But
Bellegarde would not be bullied, and he civilly, but quite firmly,
reminded Bentinck of his government's instructions to keep on good
terms with Murat. To be lectured was more than Bentinck could
stand from anybody, so he broke up the council of war that he had
called, and betook himself to Bologna in a huff. Here he drew up
instructions to Sir Robert Wilson to proceed at once to the head-
quarters of the King of Naples and piesent his ultimatum. And
here I must ask you to consider once more that Bentinck was not
empowered to make an ultimatum at all : his instructions were not
to seek a quarrel, but to cement a peace. The particular point that

670 Mr. Walter Freicen Lord [March 11,

he cliose to join issue over was the occupation of Tuscany. Murat
was in possession ; Bentinck said that Murat ought to withdraw his
army and hand over the country to England. Bellegarde said that,
as a middle course, the best thing to do would be to summon the
destined occupant of the Tuscan throne — the Grand Duke of
Wiirzburg — so that neither English nor ^Neapolitans should occupy
the country.

Murat offered to share Tuscany with Bentinck, or to allow him
to occupy Via Reggio and Lucca Genoa and Pisa, thus commanding
all the military roads, or (if Bentinck would sign the treaty) to
evacuate Tuscany altogether. A more conciliatory temper it would
be impossible to hhow.

Tiie utter futility of the whole squabble is not realised unless
we keep clearly in our minds that the object of the alliance was for
both armies to get out of Tuscany as soon as possible and cross tiie
frontier into France. But Bentinck only wanted to pick a quarrel,
and he did it this time most effectually. I wish that I could read
you his iustructions to Sir Robert Wilson. They would show, better
than any words of mine could do, that he intended the negotiat on to
fail. I will quote, however, tv\o or three sentences of his secret
instructions to Wilson. " I will not hear of any interference."
Inteiference ! between allies in a common cause. "An immediate
decision must be the sine qua non of my remaining with the British
expedition." This, after three months' delay for which he alone was
responsible!

With these instructions, Sir Robert Wilson interviewed the Due
de Gallo, the Foreign Minister of Tsaples. Gallo made the offers
that I have already mentioned, and then introduced Wilson to a
private audience with the King. In the midst of the interview Gallo
entered with — I was going to say -a letter, but a communication
from Lord William Bentinck to the King. It was written in the
third person, severely lecturing the King, and couched in the most
arrogant language. The King read it silently until he came to the
word "disloyal," when he laid the letter down, stared at Wilson
repeating the word, and then taking the letter up read it through to
the end, read it a second time, handed it silently to Gallo, and signified
that the audience was at an end.

The next day the Due de Gallo sent a line to Lord William
Bentinck, simj)ly infiaming him that his language and bearing was
not in accordance with Lord Castlereagh's instructions, and declining
to hold any further communications with him. For the future, the
Duke said, the Neapolitan court would communicate direct with the
British cabinet. On the 2nd of Aj)ril, Bentinck rej^orted the inter-
view to Lord Castlereagh, adding " 1 have resolved to be no party to
a system of weak and timid policy, which, in my judgment, promises
no material present advantage, and certainly none to counterbalance
the dangerous effects of Murat's power and ambition." And Bentinck
was drawing pay to the amount of 14,000/. a year for the express

1898.] on ''Marled Unexplored." 671

purpose of carrying out that policy. That does not strike one as
being conspicuously straightforward or honourable conduct.

" The negotiations having failed," he wound up, " I return to-day
to Leghorn." I think it would have been more in accordance witli
Bentinck's "known frankness," if lie had written "in spite of every
possible concession on the part of the Austrians and the court of
Naples, I have contrived to make the negotiations fail.''

He betook himself to Palermo, gathered up his forces, despatched
a small expedition under Colonel Montresor to reduce Corsica, landed
on the Riviera on his own account, and on the 18th of Aj)ril, Genoa
surrendered to the British army.

If forgiveness be a kingly virtue, there have been few monarchs
of more truly royal nature than Joachim Murat, King of Naples.

Beutinck had been Murat's evil genius from first to last. He had
thwarted his grand design of unifying Italy, and condescended even
to such petty impertinences as wearing the violet cockade of the
Keajiolitan Bourbons in Murat's presence, and punctiliously calling
him Monseigneur instead of Sire or your Majesty. How did Miirat
revenge himself? Five days after the capture of Genoa, Murat
wrote to Bentinck congratulating him on his success. He could
never, he said, forget the wounding expression that Bentinck had
permitted himself to use towards himself as King, but as one soldier
to another he begged Bentinck's acceptance of a sword, in com-
memoration of the capture of Genoa. As there was not time to have
one of suitable magnilicence prepared, he begged Bentinck's accept-
ance of his own. The sword of Murat, the greatest cavalry leader
that ever lived, was a present that monarchs might have coveted, a
most gracious gift, most graciously bestowed. How did Bentinck
receive it ? I think there is no doubt that if he had not been roundly
rebuked by Lord Castlereagh for his misbehaviour, he would have
declined it. This is what he wrote home :

" It is a severe violence to my feelings to incur any degree of
obligation to an individual whom I so entirely despise. But having
hitherto adoj^ted, according to the best of my humble judgment, a
line of conduct towards that personage which your lordshijj has not
approved, I feel it to be my duty not to betray any appearance of a
spirit of animosity which can do no good, and may perhaps be inter-
2)ieted by so suspicious a mind to higher authority." Suspicious is
the last thing that Murat was ; and as to " higher authority," Ben-
tinck need not have been alarmed : nobody supposed that there were
two men in England so rude as Lord William Bentinck.

He concluded his despatch by hoping that the Prince Eegent
would allow him to present him with Murat's sword as a curiosity.

I have said hard things of Lord William Bentinck. What did
the Austrians say of him ?

Bellegarde looked on him as a kind of lunatic, hurrying up and
down Italy, for ever active and never achieving anything. Count
Mier said the most damaging thing ever said of him, damaging in

672 Mr. Walter Frewen Lord [March 11,

its self-restralDt. He said that he did not see how England could
expect Italy to be pacified, unless sbe would send out a man who
would jDay some attention to his instructions. But it is not so much
with Bentinck's personality that I would occupy you, as with his
policy. Now the keynote of Bentinck's policy was implacable hos-
tility to Murat because he Wi.s an adventurer, and unfaltering support
of tlie Bourbon Ferdinand because he was a legitimate monarch.
And yet, when Murat had fallen and Ferdinand was once more en-
throned at Naples, F( rdinand was not grateful for a restoration which
was almost entiiely Bentinck's work. On the contrary, when Ben-
tinck proposed to winter at Naples, Ferdinand conveyed to him a
strong hint that he would do better to stop away. Wben — Bentincl:-
like — be braved the hint, the King sent him his passports. When
Bentinck hesitated to use them, the King intimated that he would
have him arrested and turned out of Naples by armed force. All
that is not consistent, not natural. What explanation does the
historian give of so contradictory a state of things? The most
exhaustive historian of this jDcriod is an Austrian, who naturally
takes the liarshest view of Lo:d William Bentinck because he bullied
Maria Caroline, of Sicily, who was an Austrian archduchess by birth.
He says that if Bentinck's conduct at this ej)och has the inconse-
quence of a lunatic's action, it is because all turns uj)on some secret
spring of action. " Bentinck," he says, " wanted Sicily for himself.
See how that explains everything. It explains that mysterious clause
in the Sicilian constitution by which the comidete separation of
Naples from Sicily was decreed. With this in his mind, Bentinck
naturally did not want to leave Murat in Naples, b( cause that would
have entailed the necessity of leaving Ferdinand in Sicily, where
Bentinck wanted to rule himself. Nothing less than so grtat an
ambition could have caused even Bentinck to deliberately violate his
instructions for not merely a week or so, but for four months. Finally,
it explains Ferdinand's hatred for his benefactor." It does, and
most satisfactorily — if we could only bring ourselves to believe any-
thing so outrageously incredible.

At the time when this conjecture was published, it could have
been no more than a conjecture ; for the papers disclosing the actual
state of affairs were not accessible to the public.

My compliments to the Austrian for his insight. For, ladies and
gentlemen, I present you with the astounding conclusion, that the
outrageously incredible is nothing less on this occasion than the
truth. To annex Sicily to England and rule the Island himself as
Viceroy is precisely what Lord William Bentinck was aiming at.
That, and not pious wrath, was the secret of his hatred of Murat ;
that, and not attachment to the cause of a legitimate sovereign, was
the reason for his championing the cause of Ferdinand.

On the 5th of May, 1814, he received from Lord Castlereagh the
explicit command to officially disavow to the Crown Prince of Sicily
any such jjlan either of his own or of the British Government. In

1898.] on ''Marked Unex;ploredr 673

acknowledging the receipt of his orders he poured out his usual
volume of abuse of everybody concerned. In partial justification of
himself, but yet with a fine inconsistency, he wrote, " Hated though
Murat is, he is not so detested as the old King." " Badly as I think
of the Crown Prince, I cannot believe that he has broken my con-
fidence." '' Still worse as I think of the King, I can hardly believe it
even of him." In receiviug Bentinck's official disclaimer the Crown
Princo wrote that he had never breathed a word on the subject to
any one, and that he had severely scolded Prince Castel cicala.

Prince Castelcicala, the Neapolitan ambassador, whose romantic
and resounding name accords somewhat oddly with the high respect-
ability of Great Cumberland Place, where his Embassy was, had
demanded Bentinck's immediate recall as the only satisfactory protest
against his iniquitous plan of buying half the kingdom to which he
was accredited. In this coil it is evident that some one is telling the
thing which is not. The person who was saying the thing that is not
would appear to have been the Crown Prince of Sicily. The facts are
as follows.

On the 3rd of December, 1813, about a month before our story
opens, Lord William Bentinck had written to the Crown Prince and
laid before him the plan of surrendering Sicily to England. Sicily,
he wrote, had never paid Naples ; the island could not rule itself, and
would not consent to be ruled by Naples. England was the only
power who could manage the government of Sicily. As to compen-
sation, why, money was no object. Or, if territory was preferred,
perhaps King Ferdinand would like the States of the Church.
England could have no objection to his taking them. Perhaps not :
but Ferdinand might have some objection to accepting them. All
serious adjectives are out of place when applied to that incomparable
fribble ; but the least flighty part of his character was, perhaps, his
attachment to the Church. So that, apart from the unprincipled
nature of the communication, I know not which to marvel at most, the
brutality of offering to j^lace the King of Sicily on the Pension List
of the Treasury, or the ineptitude of proposing to dower an ardent
Catholic with the plunder of the Holy See. The Crown Prince re-
plied guardedly, and made some allusions to Bentinck's instructions.
"Instructions?" Bentinck rejoined, "he had none:" the Crown
Prince must not give the proposal a second thought. It was only
" the phantasm of his own disordered brain," a " sogno filosofico," a
" castle in Spain," " le reve d'un voyageur."

From the way the correspondence runs it appears to me plain that
the Crown Prince did not believe Bentinck when he said that he had
no instructions and was acting on his own initiative. He gave the
question a week's thought, and then transmitted copies of the corre-
spondence to Castelcicala; who acted as we have seen, adding dry
comments. In the unparalleled circumstances, he said, of an ambas-
sador proposing to buy the country to which he was accredited, and
doing so without his sovereign's instructions, it was not sufficient for

674 Mr. Walter Freicen Lord [March 11,

him to say that the idea was only a philosophic dream. If Lord
William Bcntinck, he added, is subject to dreams of this kind he is
not a lit person to be accredited to my master's court. His demand
for Bentinck's recall was not acceded to ; but Bentinck soon after re-
signed his post, and so passes from our history, where he figures as
Murat's evil genius. In that capacity he was succeeded by Louis
Philippe, who was even now hastening to Paris, and whom we must
follow in his efforts to overtLrow the last Bonaparte throne lef1, in
Europe.

For we have now arrived at June 1814 ; the Emperor is installed
at Elba, and Louis XVII I. is on the throne of Fiance. The first
rumours of the Congress of Vienna are in the air, and the watchwords
of that Congress are to be Legitimacy and Restoration. Hence the ex-
tremely awkward position of the Allied Powers with regard to Murat,
who certainly was not a legitimate monarch in this sense, and at whose
gates there resided a legitimate monarch in the person of Ferdinand
of Sicily, w^ho claimed to be also Ferdinand of Naples. Nevertheless
the most ardent chamjDion of legitimacy, the Emperor of Austria, had
in fact recognised Murat, and had undertaken to engage England to
recognise him also. These promises had been made under the stress
of military exigencies, as I have endeavoured to make plain. But
Austria was loyal to them ; and it seemed that Murat was to be made
the solitary exception to the rule " Legitimacy and Restoration," and
that one Bonaparte kingdom would survive the general wreck. Thus
all that Bentinck had achieved by his perfidy and disobedience was to
postpone the fulfilment of Murat's dream. We shall see this if we
follow Louis Philippe through his interviews with various notables
throughout the year 1814.

Louis Philippe, Duke of Orleans, had married, under the protec-
tion of British shijDS and bayonets, Maria Amelia, daughter of Maria
Caroline, Queen of Sicily, and Ferdinand her husband. He was des-
tined to seek the same protection for himself and his aged wife in their
flight from France in 1848, and to die, as he had wedded, in an island
— exile, and under the British flag. He now betook himself to Paris in
order to do the best he could for his father-in-law, and to overturn, if
possible, the throne of Murat. He met with a cold rece[)tion. First,
the Emperor of Austria : " Tell your father-in-law that he must give
up all idea of returning to Naples. It is out of the question for him
to think of it." The Emperor of Russia was even more firm : " Tell
your father-in-law that peoples are no longer to be ruled by holding
out a hand to be kissed. Unless he can make up his mind to a really
liberal and constitutional form of government, he must give up all
idea of regaining the kingdom of Naples."

Seeing that Ferdinand was at this moment occupied in plunder-
ing and persecuting every upholder of the constitution who had not
already fled the country, the Emperor's words were not very en-
couraging. But the vanity and tenacity of Ferdinand were of that
colossal stamp that almost exalts potty failings into greatness. On

1898.] on ''Marked Unexplored:' 675

hearing of the Eussian Emperor's advice, he said : " The Emperor
knows nothing about it. My return is longed for as if I were the
Messiah. As for constitutions, why doesn't the Emperor grant one to
Eusjiia, since he is so ready with his advice to me ? "

Brave words ; but words brought him no nearer to moving Murat.
Murat, a fiery and impulsive man, was playing his game with great
skill. He merely sat steady under his treaty obligations, and called
upon the contracting powers to fill theirs.

Louis Philippe now approached Louis XVIIL Surely his kins-
man the King of France would help him. Perhaps the son of Egalite
Orleans was not a very welcome figure to the brother of Louis XVI.
Anyhow the King of France received him with reserve. King-
Ferdinand, he said, had all his sympathy, and he would instruct
M. de Talleyrand to urge legitimacy and restoration at the Congress
of Vienna with all possible force. He even went so far as to say
that he would never recognise Murat himself. There was an amusing
passage of arms between the two monarchs at about this period. The
of&cial gazetteer, when it appeared, contained — in accordance with
this resolve of Louis XVLEI. — the following entry :
Naples, see Sicily, kingdom of.

Murat, not to be behindhand, published the official gazetteer of
Naples with this entry :

Frarice, see Elba, island of.

All of which brave doings brought Louis Philippe no nearer to
turninu; Murat off the throne of Naples.

Bafiled in Paris, he now turned to London, and craved from
Louis XVIIL a line of introduction to the Prince Eegeut. " No,"
said the King, " I can 't do that ; the Prince would show the letter to
his ministers, and it would become an ofiicial document, but you may
give H.R.H. this message. Ask him if he remembers that Knight of
the Garter whom he received sitting." This was all the letter of
introduction that Louis Philippe brought to London. It seems to
have reference to some incident for which the Prince Regent owed
rej)aratiou,for he received the Duke graciously enough. But he held
out no more hope than the other kings. " Your father-in-law has
played his cards badly." " Votre beau-pere a mal mene sa barque," he
said. " Our engagements with Murat must be maintained." " England
has no engagements with Murat," said the Duke. But the Prince
was silent, and then he added, " I can't think what the Allies meant
by stuffing Napoleon into the Island of Elba, just outside Murat's
gates." This was a most unpleasant line for the Prince's thoughts to
take, for it led to the conclusion that if another exile were found for
Napoleon, Murat would do no harm where he was. So the Duke
hastened to turn the conversation : " Let your Royal Highness put
yourself at the head of the movement," he said, " and do for Naples
what you have already done for France."

On this appeal, vague and grandiose, the Prince Regent shook
hands with the Duke, and rang his bell for Lord Liver2)ool and

676 Mr. Walter Frewen Lord [Marcli 11,

Lord Castlereagli, wlio were in attendance. He presented these
nobles to the Duke, and referred the matter to them, glad to escape
unpledged from so tenacious a negotiator.

Lord Castlereagli had a cold ; a bad cold ; a very bad cold indeed.
Lord Castlereagli was deeply grieved at being unable to pay his
respects to His Eoyal Highness the Due d'Orleans. He was most
distressed at being unable even to receive His Eoyal Hi<ihness in
bed. The fact was that Lord Castlereagh was going to Vienna in
the Autumn, and had no mind to discuss the situation with this
pertinacious young man. Lord Liverpool, however, was not going
to Vienna, and was not of an anxious temper. He had a long inter-
view with the Due d'Orleans, and took the best step towards making
matters clear by saying at once —

Firstly, that Austria is bound to Murat ;

Secondly, that England and Enssia, having had notice of the
treaty, and having approved of it, were equally bound, and that it
was useless for the Duke to deny the fact : a fact it remained ;

But thirdly (and I think this must have been irouical), France
and Spain remained unpledged, and might do what they liked in the
matter.

The Duke fenced a little, but Lord Liverpool drove his conclusions
home. If his advice were asked, he said, he would not recommend the
alliance of two Bourbon kings, with the object of restoring a third ;
that a French army entering Italy would produce a very bad im-
pression ; and that li Louis XVIII. allied himself with Ferdinand in
order to attack Murat, of course the feeling of England towards
Sicily would undergo a considerable change. There was a marked
menace in the last warning, and Louis Philippe shifted his ground
again. " Confess, my Lord," he said," that you hum and haw because
you are all afraid of Murat." Lord Liverpool laughed, there was
something in that. " But how would your Eoyal Highness set to
work if you wanted to get rid of Murat " ? "I would set Lord
William Bentinck at him," said Louis Philippe boldly. Whereat
Lord Liverpool grew very grave : Lord William, he said, had been far
too hasty with Murat, and had given him very just grounds of com-
plaint. So far Louis Philippe had not scored a point, and now
Lord Liverpool tried to reason him out of his position. Even if we
turned out Murat, he argued, there was no compensation possible for
him ; there was no other throne that we could offer. " W^hy a throne ?
then why not money " ? " By all means, if he would take it." " Oh,
he would take it fast enough if the British fleet were in the Bay of
Naples." " But then who is to pay it " ? "Why of course, my Lord,
those powers who have guaranteed Murat's throne." That was the
only point that Louis Philippe scored off Lord Liverpool. He now
waited on Prince Metternich, and opened up with his remark that
Murat was not to be depended on. But then, rejoined Metternich,
no more is your father-in-law, you must wait for the Congress. The
Due d'Orleans had been so pertinacious that Lord Castlereagh's cold

1898.] on ^'Marked Unexplored" 677

had had time to recover, and the Duke, encouraged perhaps by the
incident, interviewed him and pressed for an immediate decision. But
Lord Castlereagh was not so easily squeezable as Louis Philippe
imagined. An immediate decision is quite out of the question, he said ;
" your Eoyal Highness must wait, like all of us, for the Congress."

" Je ue j)us rien gagner," he sighed.

And yet, at the moment when he was complaining that he could
make no way, he had in fact won his cause. Ferdinand, by himself,
was a neglisjible quantity in his own cause. The sovereigns of
Europe held him as a incumbrance in their cause. They were
fighting the cause of monarchy, and he was a disgrace to the cause
of monarchy. They were fighting the cause of legitimacy, and
Ferdinand was the incarnation of all the qualities that made the
word legitimacy an abomination in the ears of the peoples;

If it had not been for Bentinck and Louis Philippe, Ferdinand
would never have returned to Naples.

Bentinck's conduct was highly improper, but, as a matter of fact,
it did prevent the definite recognition of Murat. Louis Philippe's
adroitness and pertinacity produced the general imjiression that
Murat was rather a nuisance than otherwise. The result was that
when the Dukes of Gallo and Campochiaro claimed admittance to
the Congress of Vienna as Murat's representatives, it was refused to
them.

Talleyrand, the plenipotentiary of Louis XVIII., tried to push
his advantage further. But Metternich was firm. "I will never,"
he said, " advise my master to repudiate the treaty with Murat. It
was made in an hour of stress when we had need of his help, and I
will be no party to repudiating it now. But," he added, " you know
Murat's temper. He has so far exhibited great self-restraint. Sooner
or later he will make a slip, and we shall profit by that."

1 am glad that my time has drawn so near to its close, and that I
can do no more than hurry through the last year of Murat's life.
Prince Metternich was quite right, Murat did make a slip, and the
Austrians did take advantage of it. They entered his territory, he
was defeated in battle and fled. Ferdinand, the Messiah as he called
himself, returned to his faithful Neapolitans, and Murat wandered in
exile. His private fortune of twelve millions of francs had been
spent in maintaining the royal state of Naples. All that he carried
into exile with him was a handful of gold pieces and some diamonds.

At last, when at the end of his resources, there came a helping
hand from Austria, The Emperor created him Count of Lipona, and
granted him a passport to Austrian dominions : doubtless a provision
would have followed. It came too late. That very morning he had
completed his preparations for a last desperate attempt. " The die
is cast," he cried, as with the patent of Count of Lipona in his pocket,
he set sail for Calabria, bent on a struggle for the throne of Naples.
He had miscalculated. There was no rising in his favour. He
was taken prisoner, tried by a Court Martial, of which nearly

y(5L. XV (No 92.) 2 Y

678 3Ir. Walter Frewen Lord on 'Marked Unexplored." [Marcli 11,

every raembor had been decorated by his own hands, condemned
and shot.

"As an act of justice or an act of policy his punishment is equally
to be justified," wrote Bentinck's successor, as a comment on the
tragedy. Perhaps : only when one remembers 1848 and 1859, 1866
and 1870, wl en one remembers the long agony through which Italy
had to pass before she attained that measure of unity that Murat was
endeavouring to win for her in 1815, our only consolation for Murat's
death must be the reflection that the Red Cross of Savoy now waves
over the Peninsula from end to end.*

The discourse was illustrated by four maps.

[W. F .L.]

1898.] Mr. J. Mansergh on Bringing Water to Birmingham. 679

WEEKLY EVENING MEETING,
Friday, March 18, 1898.

Sir Fkederick Bramwell, Bart. D.C.L. LL.D. F.R.S.
Hon. Secretary and Vice-President, in the Chair.

James Mansergh, Esq. V.P. Inst. C.E. F.G.S. M.B.L

The Bringing of Water to Birmingham from
the Welsh Mountains.

The city of Birmingham has an area of 12,365 acres ; and the
parliamentary limits within which the Corporation are bound to
supply water extend to 83,221 acres, or 130 square miles — an area
10 per cent, in excess of that of the County of London. This district
varies considerably in elevation, being 270 feet above sea level in
the north-east corner, and rising to 800 feet in the south-west. As
compared with this, the highest part of Hampstead Heath, in the
north-west of London, is 450 feet. The population within I he limhs
at the time of census taking in 1891 was 647,972, and is believed to
be now over 700,000. The water is at present obtained from tiye
local streams, and from six wells sunk in the New Ked Sandstone
which underlies the city and its neighbourhood.

In 1890 I was called in to investigate the whole question of the
future of the water undertaking. My advice to the committee, put
shortly, was —

1. That the water obtainable from the local streams, flowing as
they do through populous districts, would go on constantly increasing
in impurity, and the greatest care would have to be exercised in order
to ensure its safety for domestic use.

2. That the addition to their resources by any impounding works
which could be constructed on these streams, or by sinking more
wells, would carry them on for only a comparatively few years, at
the end of which time they would inevitably have to go much
further afield, and the money they hud spent would be practically
lost.

3. That the distant unpolluted sources, at sufficient elevation to
supply Birmingham by gravitation, were comparatively few, and that
if their acquisition were delayed even for a few years only, the chances
were that they would have been secured by some other community,
possibly London.

This advice was accepted, the result being that a Bill was
promoted in Parliament in the Session of 1892, by which the
Corporation sought powers to utilise the waters of the rivers Elan
and Claerwen flowing from an area of 7 1 square miles in the counties

2 Y 2

680 Mr. James Manser gh [March 18,

of Radnor, Brecon and Cardigan. These rivers are tributaries of the
Wye, which, passing through Radnor, Brecon, Hereford, Monmouth
and Gloucester, joins the Severn near Chepstow.

Diagram No. 1, being a map of England, shows the relative
positions of Birmingham and the Elan shed, with the aqueduct
(§0 miles). It also shows the Stockton and Middlesbrough
(35 miles), the Manchester Thirlmere (100 miles), and the Liver-
pool Vyrnwy (66 miles), schemes all executed ; and in addition the
Welsh scheme for London (170 miles), projected by my friend
Sir Alexander Binnie.

In order to obtain complete control of the drainage area, and thus
secure the water from pollution, the Corporation asked Parliament to
allow them to acquire the whole of it by purchase, a proposition which
induced the opposition of the landowners, the Commoners and the
Commons Preservation Society. The Bill was also opposed by a
number of property owners upon the line of aqueduct, by a small
section of Birmingham ratepayers, by the Corporation of Hereford,
and by the London County Council ; the ground of the last-mentioned
opposition being that the source of supply was an exceptionally good
one, that therefore the Council might some day like to get hold of it,
and that Birmingham ought to wait until London had made up its
mind. We were most effectively assisted in combating this ojjposition
by your worthy Honorary Secretary, Sir Frederick Bramwell, who
had been engaged in the Liverpool fight twelve years previously, and
was able to testify that a similar objection was made at that time by
the Metropolitan Board of Works to the taking of the waters of
the Vyrnwy to the great Lancashire seaport, and to show that the
London water question was no further advanced in 1892 than it was
in 1880. This London contention was met by setting out in detail
the many streams in the Welsh mountains which were available for
the Metropolis, but too low for Birmingham ; streams which, when pro-
vided with proper storage reservoirs, were competent to supply nearly
500 miUion gallons a day without touching the Elan and Claerwen.

In addition to these oppositions we had of course to fight — as
happens in all water Bills of this class — the question of the amount
of compensation water to be paid to the river for the right to divert
the water authorised to be taken for the supply of Birmingham. In
the case of works established upon the rivers of Lancashire and
Yorkshire, whose waters are utilised for manufacturing purposes
nearly up to their sources, this is a serious question, but fortunately
in the whole course of the Wye, and the Elan below the point of
abstraction, there is not a single case of such utilisation even for
driving the wheel of a corn mill. This did not, however, prevent
most exorbitant claims being set up by riparian owner's on account
of their fishing rights — not, however, by the net-fishers in the lower
reaches who make their livelihood out of the fishing, but by sports-
men who handle a rod for diversion. In the Bill as deposited we
had proposed that the quantity of compensation water should be 22J

DIAGRAM No. 1,

0

"Ik \ ^^\^^^ MIDDLESBRO-

Stockto

Map of England and Wales, showing the Manchester Thirlmere,
Liverpool Vyrnwy, Stockton and Middlesborough, and the
Birmingham Elan Schemes; also the Proposed Welsh Scheme
FOR London.

682 Mr. James Manpergh [March 18,

millions of gallons per day : the rod fishers demanded forty millions.
They were assisted by the Wye Fishery Board, and, in the back-
ground, by the officials of the Board of Trade who administer the
Salmon Fisheries Acts ; and ultimately a compromise was come to by
which the quantity was fixed at 27 million gallons a day. Since the
works have been in course of construction we have had the oppor-
tunity of measuring the flow of the river at the spot where the
27 millions will have to be discharged, and have found that in very
dry weather it falls to something under -ij millions, so that the
quantity passing down will, so soon as anv water is taken to
Birmingham, be increased at such point six-fold. Of course the
capability of so benefiting the river is due to the storing of flood
waters in the reservoirs to be constructed.

Another incidental benefit arising out of this impounding will be
the reduction in the volume and violence of destructive floods in the
river below. The amount of compensation water in these cases is a
fairly well recognised proportion of the water collectable from the
watershed area, tljat is to say, where the water is used for trade or
manufacturing purposes the proportion is one-third, and where there
are only ordinary riparian — including fishing rights — it is about one-
fourth. The qujintity of water collectable is as-ccrtained from the area
of the gatlicring ground and the rainfall upon it less the evaporation
and the volume of water inevitably overflowing from the reservoirs in
times of flood. Thus the area we are here dealing with, was deter-
mined by accurately marking upon the plans the parting lines or
watershed boundaries after careful examination, and in some cases
instrumental levelling upon the ground. By measurement from the
plans the area was found to be 45,562 acres, the first factor in the
calculation, 'i he area is shown by a photograph of a model of the
watershed (Diagram No. 2).

The model was made on a scale of 6 inches to a mile, that is,
880 feet to an inch horizontal, and 300 feet vertical, and upon it the
reservoirs are represented as made and filled with water. The rain-
fall might have been a much more difficult thing to determine than
the area, hut that very fortunately the Lord of the Manor, Mr. Kobert
Lewis Lloydj and his fither before him had kept a rain-gauge regu-
larly from the year 1871 onwards, at the family mansion of Nant-
gwillt, in the lower part of the Elan Valley, and at a spot on the
watershed area to be appropriated.

So soon as it seemed jDrobable tliat the matter would be proceeded
with, several other rain-gauges were erected at several pomts upon
the shed, with the assistitnce of Mr. Symons, the last, and a most
worthy gold medallist of the Society of Arts. Then, by a comparison
of these with the long-term gauge at Nant-gwillt and others in the
surrounding country, it was decided that the mean annual fall of a
long ser'es of years upon the watershed might be taken at about
C8 inches, and the average of three consecutive dry years at 55 inches
— this latter being the figure always used in these estimations — as

DIAGRAM No. 2

AREA OF WATERSHED... 45.562 ACRES

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MONTHLY RAINFALL AT NANTCWILT

1898.] on Bringing Water to Birmingham from Wales. 683

first suggested by the veteran waterworks engineer and hydrologist,
the late Mr. Hawksley. The greatest rainfall was in 1872, viz, 93-86
inches ; and tlie least was in 1892, viz. 43 '44 inches.

Diagram No. 3 shows the rainfall. The upper one gives the
yearly fall at Nant-gwillt from 1871 to 1896, with the meau of that
term, and also the mean of the lowest tliree consecutive dry years.
The lower one shows the monthly fall at the same place for the same
period. It is very usual to take 14 inches as the amount of evapora-
tion, but, in order to be on the safe side and to allow amply for loss
by overflow, 19 inches were deducted from the 55, leaving 36 as
collectable by means of the reservoirs intended to be constructed.
Taking the mean of three consecutive dry years, the rainfall in one
year upon the watershed area would be equivalent to 252,495,491 tons
of water, of which 63,950,823 would be lost by absorption or evapora-
iton, and 2^,154,608 tons by overflow, leaving 165^390,060 tons as
collectable in the reservoirs. In a year of maximum ram like 1872,
the total quantity falling upon the watershed would be 431,116,756
tons, and the volume overflowing from the reservoirs into the river
would be correspondingly increased. Further observations since the
Bill was in Parliament have satisfied me that we may calculate on
obtaining from the works 75 million gallons a day for supply, in
addition to the 27 millions for compensation.

Considered geologically the whole of the watershed area consists
of rocks of Lower Silurian age, principally inferior slates, but in parts
of very hard grits and conglomerates. It is the presence of thick
bands of the latter stretching across the Elan, at a place called Caban
Coch, and resisting degradation, which has determined the position of
the contraction in the sides of the valley and rendered it so eminently
suitable for the location of a barrier dam. At this spot the bed of
the river is 700 feet above Ordnance datum, the bottom of the valley
being about 200 feet wide, and at 120 feet higher, only 600 feet. Im-
mediately above this contraction the valley widens out into a broad
"/a^," and 1540 yards higher up, the river C'laerwen joins the Elan
on its right bank.

These conditions pointed unmistakably to the Caban as the site
of the lowest dam, and consequently determined the area of gathering
ground to be utilised.

The height of the wall to be built was after milch consideration
fixed at 122 feet above the bed of the river, and the contents of the
reservoir behind it will be nearly 8000 million gallons. As compared
with the height of this wall above the river, the Vyrnwy (Liverpool
works) is 85 feet, and the Thirlmere (Manchester works) 50 feet.
The river Elan has in the part aflfected by this dam a rise of 30 feet
in a mile, so that the 122-feet barrier backs the water up that valley
4 miles, and up the Claerwen, which is somewhat steeper, about
2J miles. The length of drought which it was deemed advisable to
guard against was fixed at 180 days, and consequently the total
storage to be provided was nearly 18,000 million gallons, or 10,000

684 Mr. James 3Iansergh [March II

millions more than the Cahan Coch reservoir would contain. For the
purpose of selecting the positions of other reservoirs than the Caban
higher up, the two valleys were levelled and closely contoured to
above the highest possible site on each, and by this means the exact
positions of five others were determined, giving the greatest impounding
capacity icith the least amount of structural wcrJc.

On Diagram No. 4 are given longitudinal sections of the two
valleys, showing that on the Elan, above the Caban, there is to be
a dam at Pen-gareg, and another at Craig-yr-allt-goch, and on the
Claerwen at Dol-y-mynacb, Cil-oerwynt and Pant-y-beddau. In the
order named, tlieir respective heights are 128 feet, 120, 101, 108, and
98 ; and tlie reservoir capacities 1330, 2000, 1680, 3150, and 1940
million gallons respectively.

A unique feature in the scheme is the provision of what has been
called a suhmergcd dam, to be built across the Caban C<5ch reservoir
at a point nearly a mile and a half above the main wall, and called
Caregddu, its precise function being to hold the water up behind it
high enough to charge the aqueduct conveying the water to Birming-
ham^ It is described as submerged, because until the water has
been lowered 40 feet it will be drowned and out of sight. The neces-
sity for this device comes about in the following way, viz. at the
Birmingbam end of the aqueduct the water is to be delivered into
a large service reservoir at Frankley, about 6 miles from the centre
of the city, whose top water will be 603 feet above O.D. From
the commencement of the aqueduct in the side of the Caban reser-
voir to Frankley is a distance of nearly 74 miles, and in this
length the fall required to convey the water is in round figui*es
170 feet, so that the invert of the aqueduct at its inlet will be 770 feet
above O.D. or 70 feet higher than the bed of the river at Caban
Coch. Now the water must of necessity never fall below this inlet,
or the aqueduct could not be charged, and therefore the submerged
dam is to have its crest at 782 O.D. being high enough to fill the
aqueduct; the cross-section of which will be described later on.

Diagram No. 5 explains this more fully. A is the main Caban
wall, built at a spot where the bed of the river is, as before stated,
700 feet above O.D., its crest being 822 ; B is the submerged wall,
with a crest level of 782 ; c is the entrance to the aqueduct, with its
invert level at 770.

When the reservoir is full, the layer of water between 822 and
782, 40 feet thick and having a surface area of 600 acres, contains
4585 million gallons. Now suppose very little water were coming
down the rivers in a time of great drought, 27 million gallons have still
to be sent out for compensation every day at a, and dealing with the
first instalment, another 27 millions have to go down the aqueduct
to Birmingham ; then this combined draught of 54 millions would
draw down the water from 822 to 782 in about 80 days. The quantity
of water below 782 between Caban Coch at a and Carregddu at b
is 2565 million gallons, and would therefore sufSce to pay the com-

DIAGRAM No. 4.

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CABAN COCH DAM.

DIAGRAM No. 6,

BOUZEY DAM.

FLOOD LEVEL

1898.] on Bringing Water to Birmingham from Wales. 687

Ijensation water for another 100 days. In this way a drought of
180 days is provided for, the water for supply during the 100 days
coming from the Pen-gareg and Craig-goch reservoirs, higher up the
Elan. They hold together 3330 million gallons, and are therefore
fully competent to ensure this.

The water darkly shaded on the diagram above the submerged
dam and below 782, cannot of course be counted as effective storage,
as it cannot be drawn down without leaving the aqueduct inlet high
and dry, but it will of course be in no sense stagnant, because the
quantity going to Birmingham must always be running through it.
When the second and following instalments are required for supply,
the reservoirs on the Chierwen will have to be made in succession
as required, and the addition of the water obtainable from them
will enable the 40 feet " slice " between 822 and 782, which they
will always be rei:)leting, to maintain the increased delivery by way
of the aqueduct and the com25ensati()n as before, leaving the 2565
millions below 782 for the last 100 days of the drought. In order
to delay as long as possible the making of the Claerwen reservoirs,
a tuimel 1^ mile long is to be driven from the Dol-y-mynach
reservoir on that river to above the submerged dam, so that its
natural unstored waters can be used for supply, the respective levels
at each end admitting of this being done comfortably.

In this country Imudreds of impounding reservoirs have been
constructed for the storage of water for canal purposes and for town
sup2}ly, and a very large majority of these have banks of earth sup-
porting an internal wall of puddled clay, which forms the watertight
part of the barrier.

There are still only very few stone dams of any great size in
England, although many are to be found on the Continent of Europe.
The Ehan and ('laerwen valleys were, however, peculiarly adapted
for such structures, the dam sites being all on rock practically to the
surface, and plenty of stone for building at no great distance, the
material for earth banks being, on the other hand, deficient.

It may be interestino to show a cross-section of one of these stone
dams, and on Diagram No. 6 you have the Caban Coch which we are
now building, and alongside it that of the Bouzey dam, near Epical,
in France, which failed about three years ago with very disastrous con-
sequences. I invite you to compare these two profiles, and note the
relative thickness of the walls at the same depth below the water sur-
face, which, of course, determines the pressure. In this dam (Bouzey)
the line of stress, instead of falling within the middle third of the
profile, as it ought to do, was very much nearer the down-stream face at
the point of failure ; the weight of the structure was under 130 lbs.
per cube foot, and neither the stone nor the mortar of which it was
built was of good quality. The failure was no doubt due to the fact
that when the reservoir was full the water face of the wall at the
point of fracture, owing to the improjjer form of cross-section, was sub-
jected to a tensile strain which the material was not competent to boar.

688 Mr, James Manser gli [March 18,

This strain Professor Unwin has calculated at a ton and a quarter per
square foot, which was sufficient to make a horizontal tear or rent
along the back of the wall. Once this was made the water would enter
it, and, acting upwards as a wedge, widen the rent and ultimately
overturn the part of the wall above, cutting it right across vertically
at each end of the disturbed part, a length of about 190 yards.

The structure of all the walls in the Elan Valley will be identical
in character ; they are being formed of blocks of stone (plums as the
men call them) practically unhewn, varying from 5 or 6 cwt. to as
many tons in weight, built so as to avoid horizontal bedding planes
but with good vertical bonding, and embedded in and surrounded by
a matrix of high-class Portland cement concrete. Both the up and
down stream faces are being finished with heavy broken-coursed and
rock-faced grit or conglomerate blocks closely jointed. The stone
weighs about 170 lbs. per cube foot and the concrete about 146, and
we are aiming at getting a little more than half the mass oi plums, so
that the finished weight of the dams shall be as nearly as possible
160 lbs. per cube foot. The design of the walls is such that no
effective tensile strain can ever come upon their water faces, but if it
did, the structures as put together will resist a tensile strain of at
least 12 tons per square foot. When the Caban reservoir is full the
total water pressure against the exposed face of the dam will be about
60,000 tons. The work is being so built that there shall be no
interstices in it, and that each dam when finished shall be to all
intents and purposes a monolith, only removable by some great con-
vulsion of nature. Without reckoning anything for the cohesibility
of the structure, but only considering the weight, the factor of safety
against overturning (as did the Bouzey) is from 3^ to 4.

The drainage area above Caban Coch is by far the largest that
has been hitherto dealt with in this country in constructing works of
this character. Deducting the reservoirs, the Manchester Thirlmere
area is 11,000 acres, the Liverpool Yyrnwy 22,000, and this is 44,000;
The provision to be made for passing flood waters during the execu-
tion of the works is consequently a very important matter. At the
Caban it is quite within the range of probability that at the very
height of a flood 700,000 cube feet a minute may have to be dealt
with.

Diagram No. 7 is an outline drawing showing the way in which
we are arranging for the passage of such a flood during constructioDj
and how it will be disposed of when it comes afterwards with all
reservoirs full.

First of all we cleared out of the bed of the river o?i and for some
distance heloiv the base of the wall a very great number of large
boulders and some rocks in sHii in order to enable the water to run
freely away. We then erected a concrete and timber stank on the
Breconshire side of the river to elclude the water, and thus allow of
the excavation for the foundation of that end of the wall being got
out and the base of the wall and the ferecon culvert built. This has

DIAGRAM No. 7.

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630 Mr. James Mansergh [March 18,

all been done, the wall having been carried up to 730 O.D., or 30 feet
above the bed of the river, the water passing meanwhile along the
left side of its old course. We have now completed a similar stank
on the Radnor side, and are getting out the foundation inside of it, and
the building of the wall and the Radnor culvert will follow in due
course. Then a stank of concrete will be erected up to the level of
730, abutting against the wall at the upper and ihner end of each
culvert. This stank being finished, we shall be in a position to
impound water behind it to the extent of 240 million gallons, and to
charge the two culverts (which are 16 feet in diameter) under a head
over the centre of 22 feet, and this combined storage and power of
discharge through the culverts will enable us to pass a maximum flood
without interfering with the conduct of the works. The excavation
for the foundation of the central part of the wall can then be got out,
and the wall be built between the two ends (which are being finished
with vertical joints, dovetailed in plan) up to 730, after which the
remaining 92 feet in height of the wall can be erected without further
trouble.

"When the wall has been finished to its full height the inlet ends
of the two culverts will be closed. Whi st they are performing
their function of passing the river in its normal state, and during
floods, they are fitted with cast-iron trumpets or bell -mouthed inlets
to facilitate the entrance of the water. At the proper time these
castings will be removed, and the face-plate to which they are attached
will then become the seating of a steel caisson, which will be lowered
into its place by means of guides previously fixed and drawn home
so as to form a watertight junction by bolts inside. These doors or
caissons are competent to bear the pressure due to a full reservoir, viz.
about 560 tons, and under their protection the pipes with their valves
will be laid in the culverts for conveying the compensation water to
the measuring chambers outside. Afterwards each of the caissons
will be reinforced by a mass of concrete and brickwork inside the
culvert, so that there may be no risk of the perfect and permanent
soundness and watertightness of the " stop.'' In connection with the
measuring apparatus there will be self-recording gauges and testing
chambers, and turbines driven by the compensation water actuating
accumulator pumps for working the hydraulic valves and dynamos
for electric lighting. With a full reservoir the passing of the 27
million gallons a day of compensation water will give about 650 horse-
power, gross. When the reservoir is full the water will overflow the
whole 600-foot length of the wall, unimpeded in any way, and at the
time of a high flood the depth will be about 3 feet on the crest. This
will be a magnificent sight, which I hope some of us may live to see.
On each side of the valley a channel lined with masonry and concrete
will be constructed in front of the ends of the main wall to conduct
the water harmlessly down and train it into the main channel of the
river, which will be enclosed within masonry side walls 150 feet
apart.

DIAGRAM No. 8.

1898] on Bringing Water to Birmingham from Wales. 691

At the dams higher up the river, similar means are being
provided for the passing of flood waters, modified, of course, to meet
the circumstances of each case. The Craig- goch dam is to be built
on a curve in plan, all the other main dams being straight, and will
have a roadway carried over it on arches. The submerged dam will
also have a road over it, and as upon it must be laid a railway for the
conveyance of materials up the Claerwen Valley, its ends must be
built on practicable railway curves.

Before closing this much-condensed description of the general
scheme and the works in the valley, I should like to say that out of
the 45,562 acres of the collecting area probably 40,000 consist of open
mountain pasture or moor land carrying not more than one small
sheep per acre. Diagram No. 8 gives a very fair idea of the general
character. This is the country just above the upper end of the
Craig-goch reservoir.

In the lower parts of the valleys there is some cultivated land,
which will for the most part be occupied by the reservoirs, roads
and railways, the small farmsteads being submerged and all trees
and fences being removed below top water level of the reservoirs.
Practically the whole area will be expropriated ; only the cottages of
the very few shepherds needed, being left. The old manor house of
Nant-gwillt will be drowned, as also Cwm Elan House, for some time
the residence of Shelley, and the very small Nant-gwillt Church and a
Baptist chapel, from the grave- yard of which the remains of between
60 and 70 bodies have been removed and reinterred near a new chapel
erected below Caban Coch.

Aqueduct.

I will now shortly describe the course and mode of construction
of the aqueduct (Diagram No. 9). As has already been stated, the
aqueduct commences in the side of the Caban Coch reservoir above
the submerged or Caregddu dam, and terminates in the Frankley
service reservoir, nearly 74 miles distant. At its inlet there will be
a tower containing the controlling valves and simple screens to keep
out floating matters. The aqueduct goes immediately into tunnel,
a mile and a quarter in length, through the Foel, and emerges on the
side of the hill about 800 yards below the Caban dam. At about
4^ miles it crosses over the Mid Wales Eailway where that line is in
tunnel, and at 5 miles under the river Wye, a little south of the small
town of Rhayader. At 10 miles it passes the village of Nantmel, and
at 17 goes under the Central Wales Railway at Dolau, where it enters
a tunnel 4J miles long. At 26 miles it is just south of Knighton,
that point being at the east end of another tunnel 2 J miles long. At
35 miles it crosses over the river Teme, south of Leintwardine, then
runs along Bringwood Chase to just south of Ludlow, where it again
crosses the Teme. At 52^ miles it is half a mile north of Cleobury
Mortimer, and at 58 miles it crosses over the river Severn 3 miles

DIAGRAM No. 9.

CROSS SECTION OF AQUEDUCT

DIAGRAM No. 10.

DIAGRAM No. 11

1898.] on Bringing Water to Birmingham from Wales. 693

north of Bewdley, where the pressure in thepijDes will be about 24.0 lbs.
on the square inch. At G3J miles it is just north of Wolverley, and
at 68 close to Hagley, reaching the intended Frankley reservoir at
73 miles Si chains.

In addition to the two railways above mentioned the aqueduct
crosses the Shrewsbury and Hereford Hail way at 42 miles 10 chains,
the Severn Valley Railway at 58 miles 54 chains, the Stafford and
Worcester Canal at 62 miles 70 chains, and the Halesowen and
Bromsgrove Railway at 72 miles 5 chains. In its course it also
crosses the rivers Rea and Stour, and the Teme a third time.

There are altogether —

IS^ miles of tunnel ;

23 miles of cut and cover ; and

37 J miles of iron and steel pipes crossing

valleys under pressure.

Total 73J miles.

The meaning of " cut and cover " is that the aqueduct is laid in
ground approximately parallel to and slightly higher than the hy-
draulic gradient line, so that an open trench maybe cut, the aqueduct
built in it, and the ground filled in and restored over it to its original
condition^ In tunnel and cut and cover the structure consists of blue
brick lining on a concrete backing so far as the invert and side wall
are concerned, the arch being of concrete only.

Diagram No. 10 shows the cut and cover conduit in construction,
and Diagram No. 11 the aqueduct as built across narrow valleys.

This conduit is laid almost throughout with a fall of 1 in 4000, or
about 16 inches in a mile, the exception being in the long tunnels,
which have slightly better gradients. It will carry, running some-
thing under full, 75 million gallons a day, and the first instalment of
27 million gallons a day will flow about 3 feet deep and with a sjiced
of 150 feet a minute, taking about 44 hours in its passage from
the Elan to Birmingham. In crossing valleys below the hydraulic
gradient line the aqueduct will consist at first of two 42-inch cast-
iron or steel pipes, with a fall of 3 feet in a mile, or 1 in 1760. As
the demand for water increases, a third, fourth, fifth and sixth jDij^e of
similar size will be laid.

The service reservoir at Frankley is to be divided into two equal
parts, each holding 100 million gallons. The surface water area will
be 25 acres, and the depth 30 feet. The side walls will be of con-
crete faced with blue brickwork, a skin of asphalt coming between
them and being laid also on the concrete floor. Below this reservoir
will be built a series of filter-beds, sufficient at all times to efficiently
filter all the water that is required. From a pure water tank below
the filters the gravitation mains will start into the district, and from
it will be pumped such water as is wanted for a high fringe of
sparsely populated country too high to be commanded by gravita-
tion.

Vol. XV. (No. 92.) 2 z

694 Mr. James Mansergh [Marcli 18,

Housing of Woekpeople.

I should like now to be allowed to say a few words about tbe
arrangements which have been made by the Elan Supply Committee,
with whom I am in constant touch, for the housing and general well-
being of the workpeople engaged on the works in the Elan Valley,
and their families. At my recommendation, the Committee deter-
mined to undertake the construction of the reservoirs and all collateral
works in the valley under the direct administration of their own
staff, and without the intervention of contractors. This is not the
time nor place either to defend or apologise for this decision ; suffice
it to say that up to the present time the method is giving complete
satisfaction. Having thus decided, the question arose of how the
people were to be kept together in close proximity to the works,
and it was answered by the erection of a villaoje below Cabaa
Coch, with sufficient accommodation for about 1000 people. The
houses are of wood, and are built of different types to suit varying
grades ; thus, there are huts for officials such as the missioner and
schoolmaster, for gangers, for married workmen, and for navvy
lodgers. It has not been unusual on public works to put twenty-
four men into such a hut, sleeping in pairs in twelve beds, and,
where work was going on day and night, I believe there have been
occasions when these beds have not had time to get cold. This, to
say the least of it, is not nice. The committee needed no pressing
from me to sanction the erection of the huts above described. In
the larger eight men sleep in one large room, but each man has his
own separate cubicle and single bed.

Water is laid on under pressure throughout the village ; the drain-
age system is as good as can be made ; and there is a fire brigade.
There is also a canteen, where good beer and aerated waters are to be
had at certain hours and under strict regulations ; schools for infants
and older children, with one male and two female teachers, these
rooms being used on Sundays for religious services. There is also
a large recreation hall with gymnasium, games, writing accommoda-
tion, and a circulating library, and in which are given concerts,
theatrical entertainments, and this last winter a hall. Then there
are baths and wash-houses, and a general and accident hospital in
the village, and another for infectious diseases far away up the hill-
side. The baths are, of course, patronised principally on Saturday
afternoon and Sunday morning. When first opened there was only
one charge, viz. a penny. It was soon found this would not do —
account had to be taken of different grades. If a nipper, or ordinary
tramp labourer, ivlio is not a jproud man, paid a penny, the legitimate
navvy demanded to pay more so as to be select. The foreman posed
on a still higher platform. Now, therefore, a warm bath, soap and
towel costs a penny. Ditto, with two towels, three half-pence. Ditto,
ditto, and high-class toilet soap, two-pence. There are, of course,

1898.] on Bringing Water to Birmingham from Wales. 695

ladies' days, but into the particulars of their prejudices I have not
ventured to inquire.

To keep out infectious diseases there is also a " doss house " on
the opposite side of the river to the village, where men tramping in
search of work are taken in. On admission they are made to have a
warm bath and their clothes are disinfected, and for a week they sleep
here, working with others, and are under the supervision of the doctor,
before being allowed to take up their quarters in the village. These
arrangements have hitherto been successful, and whilst two years
ago small-pox was epidemic in many parts of South Wales, and
especially on some large public works, we escaped.

In the rest of this description of the village, I am quoting from a
lecture, delivered in Birmingham on several occasions with great
success, by Mr. E. A. Lees, the highly esteemed Secretary of the
Water Committee.

" The village is on the opposite side of the river to the road,
and access is given to it by a suspension bridge constructed across
the river by the Corporation. The position of the village, in that it
has to be approached by this bridge, and that it is erected on private
ground to which there is no public right of way, is fortunate, in that
the Corporation thereby have the means of exercising a beneficent
supervision which would be impossible were it, in the ordinary sense
of the word, a public place. Nor is the supervision of the Corpora-
tion merely nominal. No strangers are allowed in the village without
permission. Every tradesman who wishes to deliver goods is re-
quired to furnish himself with a pass, on which somewhat stringent
regulations are laid down. For instance, the owner undertakes he
will not deliver any intoxicating drinks within the village ; and the
Sunday quiet and rest of the inhabitants are protected by a regulation
that, with the exception of milk, no goods shall be delivered or sold
on that day ; and these regulations are not a dead letter, for at the end
of the bridge on the village side a gate is situate, at which the bridge-
keeper is constantly in attendance, and examines the contents of every
cart before it is allowed to proceed.

" Fire hydrants are fixed on the water mains throughout, fire ex-
tinguishing apjiliances are provided at convenient points, and in the
middle of the village there is a small fire station surmounted by a
fire bell. This is the rendezvous of the fire brigade, some members
of whom are on duty every evening. The village is perambulated
throughout the night by two watchmen. All of the huts are more-
over inspected weekly by the village superintendent, with a view
to the removal of all refuse, and the prevention of the use of oil
lamps of dangerous type, and other articles likely to occasion an
outbreak of fire.

" The village day school is placed under the Education Depart-
ment, the school managers being the Chairman of the Water Com-
mittee with three officials, two of whom are resident at the works and
one in Birmingham. The buildings are certified by the Department

2 z 2

696 Mr. James Mansergh [March 18,

as sufficient for the accommodation of 168 scholars. At first, con-
siderable difficulty was experienced in bringing the navvy children
under the discipline of regular instruction, but now good progress
is being made, and, at the last esamination by the Government In-
spector, the school earned the highest possible grant,

" I must now refer to the canteen : To this institution a special
interest attaches, as we have here an experiment embodying some of
the suggestions thrown out for the regulation of the liquor traffic.
In point of fact, the canteen is a municipal public house, and is, I
think, the only instance of the kind in the United Kingdom. Oa
the question of the drink traffic there were the three proverbial
courses open to the Water Committee : —

" 1. To do nothing, and allow any enterprising publicans who
could obtain licenses to set up their establishments and conduct their
trade in the usual manner.

" 2. To attempt to prohibit the traffic altogether.

" 3. To undertake the provision of beer for the use of the com-
munity, but under such regulations as should render it least hurtfuL

" The objection to the first course is obvious. The navvies — in
common, alas, with many others — readily yield to temptations to
drink when they have the means of gratifying the appetite; and
during the summer inonkhs, when regularity in the gangs is of the
utmost importance, and at the same time when earnings are highest,
there would be the greatest likelihood of the demoralising and
disastrous effects of drunkenness asserting themselves.

" To the second course the objection was none the less marked.
The people, rightly or wrongly, will have their beer, and without
facilities to obtain it in a legitimate manner, they would decline the
place altogether or resort to illicit meaiis to supply themselves. It
was held, therefore, to be impolitic to attempt prohibition, and I think
it would have been unwise to prohibit altogether the sale of beer.

" The third alternative course, then, was that adopted, namely, to
provide beer under stringent regulations. The canteen is placed
in charge of a manager, in whose name the license stands. The
manager has no interest in the sale of the drink ; his salary is fixed,
and is sufficiently liberal to command the services of a thoroughly
reliable and respectable man. The points against which he must
guard himself are, incivility to customers on the part of himself or
his assistants, lack of cleanliness in the house and drinking vessels,
adulteration of the liquors, selling out of hours, and disorder and
drunkenness on the part of his customers. If he is able to avoid
offence in all these respects he is thought no worse of if the
takings fall off, and no better of if they increase. To promote the
objects in view, stringent regulations have been enacted ; and the
regulations are not merely printed and hung on the walls, but are
actually enforced. The sale of drink is refused to men who show
signs of having had enough, or who have already been sujjplied up to
the stipulated limit. No women or children are permitted in the bar-

1898.] on Bringing Water to Birmingham from Wales. 697

Even in the out-door department no woman under 21 years of age is
served, and no boy under 16. The house is closed every night at nine
o'clock, and the inspection and co-operation of the police are courted
in every way. Every effort is made to sell a thoroughly wholesome
and pure beer. A regular system of sample taking and testing is
carried out, samples being taken without notice from time to time
and forwarded to Birmingham for analysis in cases marked with num-
bers only, so that the analyst cannot tell from what brewers the beers
are purchased.

" Now as to the social results. "While we cannot say that by our
attempt to regulate the drink trafftc we have created a ' Utopia,' we
may fairly say, and indeed we claim, that we have reduced the evil
results of drinking to a minimum, taking into consideration the fact
that on the oj)posite side of the river, within half a mile of the village,
another public house exists, which is conducted on the usual lines.
Persons qualified to judge speak in the highest terms of the results of
the experiment.

" One of the declared bases of the Elan village canteen is that the
profits are devoted to the social well-being of the community. First,
the whole of the cost of the day school, beyond the Government
grant, and including the cost of the building, is provided from the
canteen profits ; in other words, the profits take the place of what in
an ordinary community woukl be the School Board rate. Second, the
cost of erecting and maintaining the public hall, with the library,
gymnasium and reading room, is provided from the same source ; re-
creation grounds for the workmen and clerical stalf, the deficit on
the bath house, and occasional help to charitable institutions, are all
defrayed from the canteen profit."

The men are taken up the valley from the village early in the
morning and brought back after their work in railway carriages, so as
to save time and their exposure in open trucks, and the children from
the upper w^orks huts are brought down to school and returned home
in the same way ; with this ride in view the parents have no trouble
in getting them away to their lessons.

[J. M.]

698 The Dean of Canterbury

WEEKLY EVENING MEETING,

Friday, March 25, 1898.

Sir James Crichton-Browne, Treasurer and Vice-President,
in tlie Chair.

The Very Key. the Dean of Canterbury, D.D. F.E.S.

Canterbury Cathedral.

(Abstract.)

The Friday Evening Lecture was delivered by the Very Eev. the
Dean of Canterbury, who, at the request of the President, took as his
subject " Canterbury Cathedral." After speaking of the difficulty of
steering between the Scylla and Charybdis of saying too little or too
much in dealing with the story of a cathedral which had been closely
connected with the history of England for thirteen centuries, the
lecturer touched, first, on points of interest connected with Mercery
Lane and Christchurch Gate, and the ancient and famous King's
School. He spoke of the many styles of architecture still visible in
the cathedral — Roman and Saxon, Early and Late Norman, Decorated,
Early and Late Perpendicular, and modern — which mark the chauges
of a thousand years. To show how completely the cloisters are, as
Professor Willis called them, " a perfect museum of mediaeval archi-
tecture," he showed a slide and photograph of the Martyrdom door,
where Edward I. was married to Margaret of France. The Norman
door, by which Becket entered, was superseded by the Early English
triple arcade of 1290, overlaid about 1400 by the fan-shaped shafts
and groins of Prior Chillenden, into which has been inserted the
Perpendicular door of Archbishop Morton, about 1490. He then
gave a very rapid sketch of the main events in the history of the
structure, which was burnt down (by the Danes) in 1011, and again
burnt down in 1067 and 1174, amid the wild emotion of the people,
described \)y Gervase, who witnessed it. After describing how it was
rebuilt by William of Sens and William the Englishman, and the
later additions of Archbishops Simon of Sudbury, Arundel, Courtier,
and Morton, he spoke of the cloisters, and described the daily life of
a mediaeval monk, the hardships of which sufficed to account for the
immense size of the infirmary, of which the ruins still remain. As
an illustration of some of the memorable scenes for which the
cathedral is famous, Dr. Farrar rapidly described, from original
sources, the circumstances which attended the murder of Becket.
This was illustrated by a reproduction of the ancient painting, now
mainly obliterated, on the tomb of Henry IV. After alluding to the
Becket pilgrims and tLc relics, and the famous visits of various

1898.] on Canterbury Cathedral. 699

sovereigns, and of Erasmus and Dean Colet, he described the memo-
rable penance of Henry II. in the crypt, which was also illustrated
by an ancient picture. He then mentioned the discovery of the stone
coffin in the nave a few years ago, and gave very strong reasons for
his own belief that it contains the genuine remains of the murdered
Archbishop. Attention was next turned to the refuge offered in the
crypt to the Walloons and Huguenots, whose French service is still
continued in the Black Prince's Chantry every Sunday afternoon.
The ravages committed by Culmer (" Blue Dick ") and the Puritans
in 1642 were next described, and the lecture concluded with a swift
glance at the recent events in the cathedral history — the burial of
Archbishop Benson, the^rs^ prelate of the Eeformed English Church
to be buried in his own cathedral after an interspace of 338 years,
since the death of Cardinal Pole ; the enthronement of Archbishop
Temple ; the visit of their Eoyal Highnesses the Prince and Princess
of Wales with their family, and a circle of illustrious Englishmen, in
1897 ; and the thirteenth centenary visit of all the English-speaking
bishops of the Empire, and of Cardinals Vaughan and Derrand, the
Archbishop of Trebizond, the Duke of Norfolk, and other illustrious
Eoman Catholic prelates and laymen.

The lecture was illustrated throughout with fine lantern slides
and large photographs of the cathedral buildings.

GENEEAL MONTHLY MEETING,
Monday, April 4, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.E.S. Treasurer and
Vice-President, in the Chair.

Miss Sarah Brisco,
Frank Clowes, Esq. D.Sc. F.C.S.
Sherard Cowper-Coles, Esq.
James E. Home, Esq. M.A.
Stephen Miall, Esq. LL.D. B.Sc.
Cecil David Mocatta, Esq.
Ernest George Mocatta, Esq.

were elected Members of the Eoyal Institution.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

Tlie Secretary of State for JwrZm— Review of Education in Bengal (1892-93 to
1896-97). fol. 1897.
Annual Progress Report of the Archaeological Survey of Western India for
year ending 30th June, 1897. fol.

700 General MontJdy Meeting. [April 4,

The Governor-General of India — Memoirs of the Geological Survey of India,
Vol. XXVII. Fart 2. 8vo. 1897.

(F. Noetling. The occurreuce of Petroleum in Burma and its technical
exploitation.)

Palsoontnlogia Indica. Ser. XV. Vol. I. Part 4 ; Vol. II. Part 1. Ser. XVL
Vol. I. Parts 2-4, 1897.
The Lords of the Admiraltt/ — Nautical Almanac for 1901. 8vo. 1898.
The Meteorological Office — Report of the Meteorological Council to 31st of March,

1897. 8vo. 1897.
Accademia dei Lincei, Eeale, Boma — Atti, Serie Quinta : Rendicouti. Classe di
Scienze Morali, Vol. VII. Fasc. 1. Classe di iScienze Fisiche,etc. ; 1° Semestre,
Vol. VII. Fasc. 4, 5. 8vo. 1898.

Atti deir Accademia Poiitificia de' Nuovi Lincei, Anno L. Sess. Vir\ 4to. 1897.
Agricultural Society of Great Britain, Boyal — Journal, 3rd Series, Vol. IX.

Part 1. 8vo. 1898.
American Geographical Society — Bulletin, Vol. XXX, No. 1. 8vo. 1898.
Astronomical Society, Boyal — Monthly Notices, Vol. LVIII. No. 4. 8vo. 1898.
Bankers. Institute of — Journal, Vol. XIX. Parts 3, 4. 8vo. 1898.
Bos'on, U.S.A. Public Library — Monthly Bulletin of Books added to the Library,

Vol. III. No. 3. 8vo. 1898.
Britiiih Architects, Royal Institute o/— Journal, 1897-98, Nos. 9, 10. 8vo.
British Association — Re-port of the Toronto Meeting (1897). 8vo 1898.
British A>'tronomiral Association — Memoirs, Vol. A' I. Part 3. 8vu. 1898.

Journal, Vol. VIII. No. 5. 8vo. 1898.
British Museum Trustees (Natural History) — Catalogue of the Madnporarian

Corals, Vol. III. 4to. 1897.
Camera Club — Journal for March, 1898. 8vo.

Chemical Industry, Society o/— Journal. Vol. XVII. No. 2. 8vo. 1898.
Chemical Society — Journal for March, 1898, 8vo.

Proceedings, Nos. 190, 191. 8vo. 1898.
Cook, Ladv {the Authoress) — Essays on Social Topics. 8vo,
Dax, SociJte de JBor(7a— Bulletin, 1897, Nos, 1-3. 8vo.
Editors — American Journal of Science for March, 1898. 8vo.

Analyst for March, 1898. 8vo.

Anthony's Photographic Bulletin for March, 1898. 8vo.

A«trophysical Journal for Feb. and March, 1898. 8vo.

Athenseum for March, 1898. 4to.

Author for March, 1898.

Bimetallist for March, 1898.

Brewers' Journal for March, 1898. 8vo.

Chemical News for March, 1898. 4to.

Clieniist and Druggist for March, 1898. 8vo.

Education for March, 1898. 8vo.

Electrical Engineer for March, 1898. fol.

Electrical Engineering for Feb. 15 and March 1, 13, 1898

Electrical Review for March, 1898. 8vo.

Engineer for IMarch, 1898. fol.

Engineering for March, 1898. fol.

Homoeopathic Review for March, 1898,

Horological Journal for March, 1898. 8vo.

Industries and Iron for March, 1898. fol.

Invention for March, 1898. 8vo.

Journal of Physical Chemistry for Jan. 1898. 8vo.

Journal of State Medicine for March, 1898. 8vo.

Law Journal for March, 1898. 8vo.

Machinery Market for March, 1898. 8vo.

Nature for March, 1898. 4to.

New Church Magazine for Mar^'h. 1898. 8vo,

Nviovo Cimento for Uec. 1897 ami Jan. 1898. 8vo

1898.] General Monthly Meeting. 701

Editors — continued.

Physical Review for Feb. 1898. 8vo.
Public Health Engineer for March, 1898. 8vo.
Science Ab>tracts, Vol. I. Pait 1. 8vo. 1898.
Science Siftings for March, 1898.
Travel for March, 1898. 8vo.
Tropical Agriculturist for March, 1898. 8vo.
Zoophilist for March, 1898. 4to.
Electrical Engineers, Institution of — Journal, Vol. XXVII, No. 132. 8vo. 1898.
Emigrants' Information 0/^ce— Canada Circular, April, 1898. 8vo.
Australasian Colonies Circular, April, 1898. 8vo.
South African Colonies Circular, April, 1898. 8vo.
Executors of the late Mrs. Armitage — Copy of a Plate representing " A Deputation

to Faraday." By Edward Armitage, R.A.
Florence, BiUioteca Nazionale Cew^ra/e— Bollettino, Nos. 293, 294. 8vo. 1898.
Franklin Institute — Journal for March, 1898. 8vo.

Geographical Society, Boyal — Geographical Journal for March, 1898. 8vo.
Grey, Henry, Esq. F.R.B.S. F.Z.S. &c. {the Aiithor)— The Classics for the Million.

New edition. 8vo. 1898.
Harvard Co/Ze(/e— Annual Reports, 1896-97. 8vo. 1898.
Imperial Institute — Imperial Institute Journal for March, 1898.
Jordan, Wm. L. Esq. M.R.I, (the Author) — The New Principles of Natural

Philosophy. 8vo. 1895.
London County Council Technical Education Board — London Technical Educa-
tion Gazette for Feb. 1898. 8vo.
Louis, D, A. Esq. — Catalogues published for the Buda-Pest Exhibition in 1 896. 8vo.
Madrid, Royal Academy of Sciences — Annuario, 1898. 12mo.
Manchester Geological Society — Transactions, Vol. XXV. Parts 13, 14. 8vo. 1898.
Massachusetts, State Board of Health — Twenty-seventh and Twenty-eighth Annual

Reports. 8vo. 1896-97.
Meteorological Society, Royal — Quarterly Journal, No. 105. 8vo. 1898.
Navy League — Navy League Journal for March, 1898. 4to.
Nova Scotian Institute of /Sc/ence— Proceedings and Transactions, Vol. IX.

Part 3. 8vo. 1897.
Numismatic Society — Chronicle and Journal, 1897, Part 4. 8vo.
Odontohgical Society of Great Britain — Transactions, Vol. XXX. No. 5. 8vo.

1898.
Oliver, Thomas, Esq, M.D. F.R,C.P. (the Author)— On the Cause of Death by

Electric Shock. By T. Oliver and R. A. Bolam. 8vo. 1898.
Paris, Societe Frangaise de Pliysique — Bulletin, Nos. Ill, 112. 8vo. 1898.
Perry-Cosie, F. H. Esq. B.Sc. {the Author)— The Rhythm of the Pulse. 8vo. 1898.
Pharmaceutical Society of Great Britain — Journal for March, 1898. 8vo.
Photographic Society of Great Britain, Royal — The Photographic Journal for Feb.

1898. 8vo.
Prince, C. L. Esq. F,R.A.S, (the Compiler) — Summary of a MeteorologicalJournal,

1897. fol.
Queensland Government — Ethnological Studies among the North-west Central

Queensland Aborigines. By W. E. Roth.
Queen s College, Galway — Calendar for 1897-98. 8vo.
Rochechouart, La Societe les Amis des Sciences et Arts — Bulletin, Tome VI.

No. 6; Tome VIL Nos. 1-3. 8vo. 1896-97.
Royal Engineers, Corps o/— Professional Papers, Vol. XXIII. 8vo. 1897.
Royal Society of London— Y ear-Book, 1896-97, 1897-98. 8vo.

Philosophical Transactions, Vol. CLXXXIX. B, Nos. 152, 153 ; Vol. CXC. A,

Nos. 211, 212. 4to. 1898.
Proceedings, Nos. 385-387. 8vo. 1898.
Saxon Society of Sciences, Royal —
Mathematisch-Fh ysische Classe —

Boriehte, 1897, Nos. 5, 6. 8vo. 1898.

702 General Monthly Meeting, [April 4^

Selhorne Society — Nature Notes for March, 1898. 8vo.

Society of ^r^s— Journal for March, 1898. 8vo.

TaccMni, Prof. P. Eon. Mem. R.I. (tJie Autltor) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXVII. Disp. 2. 4to. 1898.
Toulouse, Societe ArcMologique du Midi de la France — Bulletin, Series in 8vo.

No. 19. 8vo. 1897.
United Service Institution, Royal — Journal for March, 1898. 8vo.
United States Department of Agriculture — Experiment Station Kecord, Vol. IX.

No. 4. 8vo. 1897.
United States Patent O^ce— Official Gazette, Vol. LXXXII. Nos. 9-12. 8vo.

1898.
Alphabetical Lists of Patentees and Inventions for quarter ending June 30,

1897. 8vo.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhaudlungen, 1898,

Heft 2, 3. 4to.
Vienna, Geological Institute, Imperial — ^Verhaudlungen, 1898, Nos. 1, 2. 8vo.
Whitty, Rev. J. I. LL.D. D.C.L. (the Author)— Discovery of Whitty's Wall at

Jerusalem. 8vo. 1895. Palestine Exploration. 8vo. 1897.
Yorlishire Philosophiral Society — Annual Keport for 1897. 8vo.
Zurich, Naturforschende Geselhchaft — Vierteljahrsschrift, Jahrg. XLII. Heft 3, 4.

8vo. 1898.
Neujahrsblatt. 4to. 1898.

1898.] Professor Andrew Gray on Magneto-Optic Rotation. 703

WEEKLY EVENING MEETING,
Friday, April 29, 1898.

Basil Woodd Smith, Esq. F.R.A.S. F.S.A. Vice-President,
in the Chair.

Professor Andrew Gray, M.A. LL.D. F.R.S.

Magneto-Optic Botation and its Explanation by a Gyrostatic Medium.

The action of magnetism on the propagation of light in a transparent
medium has been rightly regarded as one of the most beautiful of
Faraday's great scientific discoveries. Like most important dis-
coveries it was no result of accidental observation, but was the out-
come of long and patient inquiry. Guided by a conviction that (to
quote his own words) " the various forms under which the forces of
matter are made manifest have one common origin," he made many
attempts to discover a relation between light and electricity, but for
very long with negative results. Still, however, retaining a strong
persuasion that his view was correct, and that some such relation must
exist, he was undiscouraged, and only proceeded to search for it more
strictly and carefully than ever. At last, as he himself says, he " suc-
ceeded in magnetising and electrifying a ray of light, and in illuminat-
ing a magnetic line of force.*''

Faraday pictured the space round a magnet as permeated by what
he called lines of force ; these he regarded as no mere mathematical ab-
stractions, but as having a real physical existence represented by a
change of state of the medium brought about by the introduction of
the magnet. That there is such a medium surrounding a magnet we
take for granted. The lines of force are shown by the directions which
the small elongated pieces of iron we have in iron filings take when
sprinkled on a smooth horizontal surface surrounding a horizontal bar
magnet, as in the experiment I here make. [Experiment to show field
of bar magnet by iron filings.']

The arrangement of these lines of force depends upon the nature
of the magnet producing them. If the magnet be of horse-shoe shape
the lines are crowded into the space between the poles ; and if the pole
faces be close together and have their opposed surfaces flat and parallel,
the lines of force pass straight across from one surface to the other
in the manner shown in the diagram before you. [Diagram of field
between flat pole faces.']

The physical existence of these lines of force was demonstrated
for a number of different media by the discovery of Faraday to which

704

Professor Andrew Gray

[April 29,

I Lave already referred, and on which almost all the later work on
the relation of magnetism to light has been founded. I am permitted
by the kindness of the authorities of this Institution to exhibit here
the very apparatus which Faraday himself employed, though for the
various experiments I have to make it is necessary to actually use
another set of instruments. [^Apjparatas shown.'] Before repeating
Faraday's experiment, let me describe shortly what I propose to do,
and the effect to be observed.

A beam of plane polarised light is produced by passing white light
from this electric lamp through a Nicol's prism. To understand the
nature of plane polarised light, look for a moment at this other dia-

Fig. 1.

gram (Fig. 1). It represents a series of particles displaced in a certain
regular manner to different distances from the mean or equilibrium
positions they originally had along a straight line. They are moving
in the directions shown by the arrows and with velocities depending
on their positions, as indicated by the lengths of the arrows. Suppose
a certain interval of time to elapse. The particles will have moved
in that time to the positions shown in this other diagram (Fig. 2), on

,.-■■'

"^1

- y'

^--r-.

\

1

>

*N

» —

'

k,

V \

,--'

Fig. 2.

the same sheet. It will be seen that the velocities as well as the
positions of the particles have altered, but that the configuration is
the same as would be given by the former diagram moved through
a certain distance to the left.

Thus an observer looking at the particles and regarding their con-
figuration would see that configuration apparently move to the left,
and this, it is very carefully to be noted, is a result of the transverse
motions of the individual particles. In another interval of time equal
to the former, the arrangement of particles will appear to have moved
a further distance of the same amount towards the left.

This transverse motion of the particles, thus shown displaced from

1898.]

on Magneto-Optic Rotation.

705

their equilibrium positions, represents the vibration of the medium
which is the vehicle of light, and the right to left motion of the con-
figuration of particles is the wave motion resulting from that vibration,
I do not say that the medium is thus made up of discrete particles,
or that the different portions of it vibrate in this manner, but there
£•8 undoubtedly a directed quantity transverse to the direction in
which the wave is travelling, the value of which at different points
may be represented by the displacements of the particles, and which
varies in the same manner, and results, as here shown, in the propaga-
tion of a wave of the quantity concerned.

In fact we have here a representation of a wave of plane polar-
ised light. The directions of vibration are right lines parallel at all
points along the wave. Ordinary light consists of vibrations the
directions of which are not parallel if rectilinear, and each vibration
is therefore capable of being resolved into two in directions at right
angles to one another. The Nicol's prism in fact splits a wave of
ordinary unpolarised light into two waves, one in which the vibra-
tions are in one plane containing the direction in which the light is
travelling, the other in a plane containing the same direction, but at
right angles to the former. One of these waves is stopped by the film
of Canada balsam in the prism and thrown out of its course, while the
other wave is allowed to pass on undisturbed.

If the wave thus allowed to pass by one Nicol's prism be received
by another, it is found that there are two positions of the latter in which
the wave passes freely through the second prism, and two others in
which the wave is stopped. The prism can be turned from one posi-
tion to another by properly placing it and then turning it round the
direction of the ray. It is found that if the prism be thus turned

Fig.

from a position in which the light is freely transmitted, we come after
turning it through 90"" to a position in which the light is stopped,
and that if we go on turning tlirough another angle of 90° a position

706

Professor Andrew Gray

[April 29,

is readied in which the light is again freely transmitted, and so on, the
light being alternately stopped and transmitted by the second prisms in
successive positions 90° apart.

The mode of passage of the wave by the Nicols when their planes
are parallel, and its stoppage when the planes are crossed, are illus-
trated by this diagram (Fig. 3) of a vibrating cord and two slits.
When the slits are parallel, the vibration which is passed by one is
passed by the other ; when they are crossed, a vibration passed by one
is stopped by the other.

Two planes of symmetry of the prisms parallel to the ray, and
called their principal planes, are parallel to one another when the
light passes through both, and are perpendicular to one another
when the light passed by the first is sto23ped by the second. We shall
call the first prism the polarising prism, or the ^oZamer, from its effect
in producing plane polarised light ; the other, the analyser. The
stoppage of the light in the two positions 180° apart of the second
prism, and its passage in the two intermediate positions, show that the
light passed by the first prism is plane polarised.

Fig. 4.

Now a beam of plane polarised light is passed through the per-
forated pole-pieces of this large electro-magnet (Fig. 4), so that the
beam travels between the pole-faces along the direction which the lines
of force there would have if the magnet were excited by a current. The
arrangement of the apparatus is as shown in the diagram. The light
is polarised by the prism P, passes through the magnetic field, and
then through the analysing prism A, to the screen. As you see, when
the second prism is turned round the ray the light on the screen alter-
nately shines out and is extinguished, and you can see also that the
angle between the positions of free passage and extinction is 90°.

I now place in the path of the beam this bar of a very remarkable
kind of glass, some of the j)roperties of which were investigated by
Faraday. It is a very dense kind of lead glass, which may be
described as a silicated borate of lead ; that is, it contains silica, boric
acid and lead oxide. The beam is not disturbed although the light
passes through the glass from end to end. I now adjust the analysing
prism to very nearly complete extinction, and then excite the magnet.

1898.] on Magneto-Optic Rotation. 707

If the room is sufficiently darkened, I think all will see that when the
magnet is excited there is a very perceptible brightening of the dim
patch of light on the screen, and that this brightening disappears
when the current is removed from the magnet. This is Faraday's
discovery.

How are we to describe this result ? What effect has been pro-
duced by the magnetic field? It is clear that the direction of
vibration of the light emerging from the specimen of heavy glass has
been changed relatively to the prism so that the light now readily
passes. It is found, moreover, that the amount of turning of the direc-
tion of vibration round the ray is proportional to the length of the
specimen, so that the directions of vibration at different points along
the wave within the specimen lie on a helically twisted surface, and
may be regarded as represented by the straight rods in the model
before you on the table (Fig. 5),

Fig. 5.

It is also found that the amount of the turning depends on the
intensity of the magnetic field — is, in fact, simply proportional to that
intensity. Hence the turning is proportional to the mean intensity of
the field, and to the length of the path in the medium, that is, to the
product of these two quantities. It also depends on the nature of the
medium. The angle of turning produced by a field of known intensity
when the ray passes through bisulphide of carbon has been very
carefully measured by Lord Kayleigh, whose results are of great value
for other magnetic work.

The law of proportionality of the amount of turning of the plane
of polarisation to the intensity of the magnetic field in the space
in which the substance is placed, is not, however, to be regarded
as established for strongly magnetic substances, such as iron, nickel
or cobalt. The matter has not yet been completely worked out, but
the turning in such cases seems to be more nearly proportional to
the intensity of magnetisation, a different quantity from the intensity
of the magnetic field producing the magnetisation. If this law be

708 Professor Andrew Gray [April 29}

found correct, the angle of turning will be proportional to the pro-
duct of the intensity of magnetisation and to the length of the path ;
and the angle observed divided by this product will give another
constant, which has been called Kundt's constant.

The rotation of the plane of j)olarisation in strongly magnetised
substances was investigated by Kundt, the very eminent head of the
Physical Laboratory of the University of Berlin, who died only a
year or two ago. Kundt is remembered for many beautiful methods
which he introduced into quantitative physical work ; but no work
he did was more remarkable than that which he performed in magneto-
optic rotation when he succeeded in passing a beam of plane polar-
ised light through plates of iron, nickel and cobalt. Such substances,
though apparently opaque to light, are not really so when obtained in
plates of sufficient thinness. In sufficiently thin films all metals, so
far as I know, are transparent, not merely to Eontgen rays, but to
ordinary light. Kundt conceived the idea of forming such films of
the strongly magnetic metals, so as to investigate their properties as
regards magneto -optic rotation. He succeeded in obtaining them by
electroplating platinised glass with such thin strata of these metals
that light passed through them in sufficient quantity for observation.
The rotation produced by the glass and the exceedingly thin film of
platinum was determined once for all and allowed for. Kundt
obtained the remarkable result that the magnetic rotatory power in
iron is so great, that light transmitted through a thickness of one
centimetre of iron magnetised to saturation is turned through an
angle of over 200,000°, that is, that light passing through a thickness
of an inch of iron magnetised to saturation would have its plane of
polarisation turned completely round more than a thousand times ; in
other words, one complete turn would be given by a film less than yoVo
of an inch in thickness. A scarcely smaller result has been found by
Du Bois for cobalt, and a maximum rotation of rather less than half
as much by the same experimenter for nickel.

The direction of turning in all the cases which have so far been
specified — that is, Faraday's glass, bisulphide of carbon, iron, nickel
and cobalt — is the same as that in which a current of electricity would
have to flow round the spires of a coil of wire surrounding the specimen
so as to produce the magnetic field. This we call the 'positive direc-
tion. There are, however, many substances in which the turning
produced by the magnetic field is in the contrary or negative direction ;
for example, ferrous and ferric salts of iron, chromate and bichromate
of potassium, and in fact most compound substances which are feebly
magnetic.

Faraday established by his experiments the fact that substances
fall into two distinct classes as tested by their behaviour under the
influence of magnetic force. For example, an elongated specimen of
iron, nickel or cobalt, if freely suspended horizontally between the poles
of our electro-magnet, would set itself with its length along the lines
of force. On the other hand, a similar specimen of heavy glass, or a

1898.

on Magneto-Optic Botation.

709

tube filled with bisulphide of carbon, would, if similarly suspended, set
itself across the lines of force. The former substances were there-
fore called by Faraday paramagnetic, the latter diamaguetic.

It might be supposed that diamagnetics would show a turning effect
opposed to that found in paramagnetics, but this is not the case.
As we have seen, bisulphide of carbon and heavy glass, which are
diamagnetics, show a turning in the same direction as that jiroduced
in iron — as indeed do most solid, fluid and gaseous diamagnetics.
Feebly paramagnetic compound substances, on the other hand, produce
negative rotation.

A theory of diamagnetism has been put forward in which the
phenomena are explained by supposing that all substances are para-
magnetic in reality, but that so-called diamagnetic bodies are less so
than the air in which they are immersed when experimented on. Thus
the diamagnetic quality is one of the substances relatively to air, in
the same kind of way as the apparent levity of a balloon is due to the
fact that its total weight has a positive value, but is less than that
of the air dispLT,ced by the balloon and appendages. Lord Kelvin's
dynamical explanation of magneto-optic ^

rotation does not bear out this view of i

the matter.

Before passing to the dynamical ex-
planation, however, I must very shortly
call attention to some remarkable dis-
coveries in this subject made by Dr.
John Kerr, of Glasgow. I have here
an electro-magnet arranged as in the
diagram before you (Fig. 6). The light
from the lamp is first plane polarised by
the Nicol P, then it is thrown on the
piece of silvered glass G, and part of it
is thereby reflected through this per-
forated pole-piece so as to fall normally
on the polished point of the other pole-
piece. Keflection thus' takes place at
perpendicular incidence, and the re-
flected light is received by this second
Nicol. When the magnet is unexcited
the second Nicol is arranged so as to
quench the reflected light. The mag-
net is then excited, and it is found that
the light is faintly restored, showing
that an effect on the polarisation of the
light has been produced by tlie magnetisation,
here that the incident and reflected light is m
magnetisation. We shall not

Fig. 6.

It is to be noticed

the direction of

pause to make this experiment. It

was arranged this morning and successfully carried out ; but the

effect is slight, and might not be noticeable without precautions,

Vol. XV. (No. 92.) 3 a

710

Professor Andrew Gray

[April 29,

which we have hardly time to make, to exclude all extraneous light
from the screen.

It would perhaps be incorrect to say that the plane of polarisation
has been rotated in this case, as it has been asserted by Eighi that the
light after reflection is no longer plane polarised, but that there are two
components of vibration at right angles to one another, so related that
the resultant vibration is not rectilinear but elliptical. There is there-
fore no position in which the analysing prism can be placed so as to
extinguish the reflected light. The transverse component necessary
to give the ellijDtic vibration is, however, in this case, if it exists, very
small, and very nearly complete extinction of the beam can be obtained
by turning the analysing prism round so as to stop the other com-
ponent vibration. The angle through which the prism must be turned
to effect this is the amount of theaj^parent rotation. The direction
of rotation is reversed by reversing the magnetism of the reflecting
pole. Dr. Kerr found that the direction is always that in which the
current flows in the coils producing the magnetisation of the pole.

Fig. 7.

Dr Kerr also made experiments with light obliquely incident on a
pole-face, with the arrangement of apparatus shown in this other dia-
gram (Fig. 7). He found that the previously plane polarised light was
by the reflection rendered slightly elliptically polarised. A slight
turning of the analysing Nicol was necessary to place it so as to stop
the vibration corresponding to the long axis of the ellipse and so
secure imperfect extinction.

These effects are, like those of normal incidence, very small, and
they can hardly be shown to an audience.

I must now endeavour to give some slight account of the theories
that have been put forward in explanation of magneto-optic rotation.
There is an essential distinction between it and what is sometimes
called the natural rotation, the plane of polarised light produced
by substances, such as solutions of sugar, tartaric acid, quartz, &c.,
some of which rotate the plane to the right, some to the left. When

1898.]

on Mngneto-Optic Rotation.

711

Fig. 8.

liglit is sent once along a column of any of those substances with-
out any magnetic field, its plane of rotation is rotated just as it
is in heavy glass or bisulphide of carbon in a magnetic field. But
if the ray, after passing through the
column of sugar or quartz, is received
on a silvered reflector and sent back
again through the column to the start-
ing point, its plane of polarisation is
found to be in the same direction as at
first. Quite the contrary happens when
the rotation is due to the action of a
magnetic field. Then the rotation is
found to be doubled by the forward

and backward passage, and it can be increased to any required degree
by sending the ray backward and forward through the substance, as
shown in this other diagram (Fig. 8).

Thus the rotations in the two cases are essentially different, and
must be brought about by different causes. In fact, as was first, I
believe, shown by Lord Kelvin, the annulment of the turning in
quartz, and the reinforcement of the turning in a magnetic field, pro-
duced by sending the ray back again after reflection at the surface of
an optically denser medium, points to a peculiarity of structure of
the medium as the cause of the turning of the plane of polarisation in
sugar solutions and quartz, and to the existence of rotation in the
medium as the cause of the turning in a magnetic field. Think of
an elastic solid, highly incompressible and endowed with great elas-
ticity of shape and of the same quality in different directions — a stiff
jelly may be taken as an example to fix the ideas. Now let one
portion of the jelly have bored into it a very large number of
extremely small corkscrew-shaped cavities, having their axes all
turned in the same direction. Let another portion have imbedded in
it a very large number of extremely small rotating bodies, spinning-
tops or gyrostats in fact, and let these be uniformly distributed
through the substance, and have their axes all turned in the same
direction.

Both portions would transmit a plane polarised wave of trans-
verse vibration travelling in the direction of the axes of the cavities
or of the tops with rotation of the plane of polarisation ; but in the
former case the wave, if reflected and made to travel back, would have
the original plane of polarisation restored ; in the latter the turning
would be doubled by the backward passage.

To understand this it is necessary to enter a little in detail into
the analysis of the nature of plane polarised light. As I have
already said, the elastic solid theory may not express the facts of
light propagation, but only a certain correspondence with the facts.
But its use puts this matter in a very clear way. In a ray of plane
polarised light each portion of the ether has a motion of vibration in
a line at right angles to the ray, and the direction of this line is the

712

Professor Andrew Gray

[April 29,

same for each moving particle. The lines of motion and the relative
positions of the particles in a wave are shown in the first diagram above
(Fig. 1). As the motion is kept up at the place of excitation it is
propagated out by the elastic resistance of the medium to displace-
ment, and the configuration of particles travels outwards with the speed
of light, traversing a wave-length (represented
in the diagram by the distance between two
particles of the row in the same phase of motion)
in the period of complete to-and-fro motion of a
particle in its rectilineal path.
Fig. 9. Now, a to-and-fro motion such as this can be

conceived as made up of two opposite uniform and
equal circular motions. Think of two distinct particles moving in the
two equal circles A B in this diagram (Fig. 9), with equal uniform
speeds in opposite directions. Let each particle be at the top of its

A B a' b'

cb cb .cp

O0

d^e i^P ^r>

/ \

?q:> cq:^ cr;^ <cp
<i^ ct> c^ c^

2 2,

<^ C46 Jct^ ct>

Fig. 10.

circle at the same instant ; then at any other instant they will be in
similar positions, but one on the right, the other on the left of the
vertical diameter of the circle. Thus at that instant each particle is
moving downward or upward at the same speed, while with whatever
speed one is moving to the left, the other is moving with precisely

1898.]

on Magneto-Optic Botation.

713

that speed towards the right. Imagine, now, these two motions to be
united in a single particle. The vertical motions will be added
together, the right and left motions will cancel one another, and the
particle will have a motion of vibration m the vertical direction of
range equal to twice the diameter of the circles, and in the period of
the circular motions.

The rate of increase of velocity of the particle at each instant is
the resultant obtained by properly adding together the accelerations
of the particles in the circular motions, and therefore the force which
must act on the particle to cause it to describe the vibratory motion
just described, is the resultant of the forces required to give to the
two particles the circular motions which have just been considered.

Now, what we have done for any one particle may be conceived of
as done for all the particles in a wave. To understand the nature of
a wave in this scheme, we must think of a series of particles originally
in a straight line in the direction of propagation of the ray, as dis-
placed to positions on a helix surrounding that direction. Fig. A

Fig. 11.

of this diagram (Fig. 10), regarded from the lower end, and the black
spots on the model before you, show a left-handed helical arrangement.
Let these particles be projected with equal speeds in the circular paths
represented by the circle at the bottom of Fisj. A. On this circle are
seen the apparent positions of different particles in the helical ar-
rangement when it is viewed by an eye looking upwards along its
axis. This motion is shown by that of the black spots on the surface
of the model (Fig. 11), when I set it into rotation about its axis.
Let the particles be constrained to continue in motion exactly in this
manner. As the model shows, the helical arrangement of the par-
ticles is displaced along the cylinder. This is the mode of propaga-
tion of a circularly polarised wave, which is made up of helical
arrangements of particles which were formerly in straight lines
parallel to the axis.

The direction of propagation of the wave is clearly from the
bottom of the diagram to the top^ and from the end of the model
towards your left to the other, when the particles have a right-handed
motion, and is in the contrary direction when the direction of rotation
is reversed. For a right-handed helical arrangement the direction of

714

Professor Andrew Gray

[April 29,

propagation for the same direction of motion of the particles is the
opposite of that just specified. The direction of propagation remains
therefore the same when the direction of motion and the helical
arrangement of the particles are both reversed. All this can be
made out from the diagram. Fig. B shows part of a right-handed
arrangement of j)articles corresponding to the opposite arrangement
of Fig. A ; and if the particles have the motions shown at the bottom
of the diagram, the propagation will be for both in the same direction
from the bottom to the top.

Fig. 12.

In Fig. 10 we suppose the periods equal and also the wave-
lengths, the distance along the axis from particle 1 to particle 9.
The combination of the circular motions A and B gives rectilinear
motion ; the combination of the wave motions of Figs. A and B
gives a plane polarised wave, the plane of polarisation of which does
not change in position. If, however, while the periods were equal,
the wave-lengths were unequal, as shown in this other diagram (Fig.
12), the plane of polarisation would rotate, as shown by the lines
drawn across the paths in the figure on the right,for the circular motions
of particles in the longer wave would gain on those in the shorter.

1898.] on Magneto-Optic Botation. 715

A little consideration will show that the direction of the resultant
rectilinear motion will, in consequence of the unequal speeds of
propagation, turn round as the wave advances, and will do so in the
direction of motion of the particles in the more quickly travelling
wave, generating the screw surface shown in the model I have already
exhibited.

We must now consider the forces. The jmrticles moving in the
circular paths have accelerations towards the centres of these paths,
and forces must be applied to them to produce these accelerations.
These forces are applied in the present theory by the action of the
medium, and it is the reactions of the partcles on the medium that
are properly called the centrifugal forces of the particles. The
requisite centreward forces then are supplied by the state of strain
into which the medium is thrown by the displacement of parts of it,
which form in the undisturbed position a series of straight arrays in
the direction of propagation, into these helical arrangements round
that direction. The greater these elastic forces the greater the
velocity of propagation of the wave.

In an elastic medium these forces depend on the amount of the
relative displacements of the particles, and will be greater for dis-
placements in the right-hand helical arrangement than for displace-
ments in the opposite direction if the medium has a greater rigidity
for right-handed distortion than for left, and the right-handed wave of
distortion will be transmitted with greater speed, and vice versa.
This is the case of solutions of sugar and tartaric acid, quartz, &c.,
for which a helical structure has been supposed to exist in the
medium.

Taking this case, refer to Figs. A and B of our large diagram
(Fig. 10), and let the right-handed wave travel the faster. Let the
waves travel up, be reflected at the upper ends, as at the surface of a
denser medium, and then travel down again. The reflected waves
are those shown in Fige;. A', B' of the diagram. By the reflection the
helical arrangement will be unaltered. But the plane of polarisation,
as we have seen, turns round in space in the direction of the motion
of the particles in the more quickly moving wave ; it therefore turns
round in the direction of the hands of a watch as the wave moves in
the upward direction in the diagram, and in the opposite direction
when the wave is travelling back. Thus the rotation of the plane of
polarisation produced in the forward passage is undone in the backward.

It is easy to see that the same thing will take place if the
reflection is at the surface of an optically rarer medium, so that the
direction of motion of the particles is the same in the reflected as in
the direct wave. The helical arrangements, however, are reversed by
the reflection, and hence the wave which travelled the more quickly
forward travels the more slowly back, and again the turning of the
plane of polarisation is annulled by the backward passage. Thus Lord
Kelvin's hypothesis of difference of structure completely explains the
phenomena.

716 Professor Andrew Gray [April 29,

We pass now to the other case, that of magneto-optic rotation.
Let us suppose, to fix the ideas, that the right-banded circular ray-
travels faster than the other, and that whether direct or reversed.
Here, as in the other case, the elastic reaction of the medium on the
displaced particles depends only on the distortion, and if there be no
structural peculiarity in the medium there must be the same reaction
in the particles in both the circular waves which combine to make
up the plane polarised one.

Thus the actions on the particles being the same for both waves,
and the velocities of propagation being different, the motions con-
cerned in the light propagation cannot be the same. There must in
fact be a motion already existing in the medium which, compounded
with the motions concerned in light propagation, give two motions
which give equal reactions in the medium against the equal elastic
forces, applied to the particles in the case of equal helical displace-
ments.

Thus Lord Kelvin supposes that in the medium in the magnetic
field there exists a motion capable of being compounded with the
luminiferous motion of either circularly polarised beam. The latter
is thus only a component of the whole motion.

In the very important paper in which he has set forth his theory
Lord Kelvin expresses his strong conviction that his dynamical
explanation is the only possible one. If this view be correct,
Faraday's magneto-optic discovery affords a demonstration of the
reality of Ampere's theory of the ultimate nature of magnetism. For
we have only to consider the particles of a magnetised body as
electrons or groups of charges of electricity, ultimate as to smallness,
rotating about axes on the whole in alignment along the direction of
the magnetic force, and with a preponderance of one of the two
directions of rotation over the other. Each rotating molecule is an
infinitesimal electro-magnet, of which the current distribution is
furnished by the system of convection currents constituted by the
moving charges.

The subject of magneto-optic rotation has also been considered by
Larmor, and two types of theory of these effects have been indicated
by him in his report on the ' Action of Magnetism on Light.' One
is represented by Lord Kelvin's theory, which is illustrated by
Maxwell's chapter on molecular vortices in his ' Electricity and
Magnetism.' FitzGerald's paper " On the Electromagnetic Theory
of the Reflection and Refraction of Light," in the ' Philosophical
Transactions' for 1880, is related to Maxwell's theory, and ex-
plains the rotation produced by reflection from the pole of a magnet
by means of the addition of a term to the energy of the system.
The other theory is also a purely electromagnetic one, and supposes
that the effects are due to a kind of seolotropy of the medium set up by
the magnetisation, and so attributes them to a change of structure
which introduces rotational terms into the equations connecting
electric displacements and electric forces. This latter theory therefore

1898.]

on Magneto-Optic Rotation.

in

regards the magneto-optic rotation as only a secondary effect of the
magnetisation, which is not supposed to exert any direct dynamical
influence on the transmission of the light- waves.

It is not possible here to enter into the subject of these theories,
but I should like to direct attention to a paper by Mr. J. G.
Leathem, just published in the ' Philosophical Transactions,' in
which the type of theory just referred to has been worked out and
compared in its results with the experiments of Sissingh and Zeeman
in reflection. These investigators made measurements of the phase
and amplitude of the magneto-optic component of the reflected light
for various angles of incidence. For both these quantities the
theoretical results of Leathem agree very well with the observed
values.

Eeturning now to the gyrostatic medium, between which and the
electro-magnetic theory, it is to be remembered, there is a corre-
spondence, we may inquire in what
way the gyrostats, when moved by
the vibrations of the medium, react
upon it, and so affect the velocity
of propagation. The motion of a
gyrostat is often regarded as mys-
terious, and it can hardly be fully
explained except by mathematical
investigation. But the general na-
ture of its action may be made out
without much difficulty. First of
all, a gyrostat consists of a massive
fly-wheel running on bearings at-
tached to a case which more or
less completely encloses the wheel.
The mass of the wheel consists in
the main of a massive rim, which
renders as great as possible what
is called the moment of momentum
of the wheel when rotating about its axis. The diagram (Fig. 13)
represents a partial section of the case and fly-vfheel of a gyrostat,
showing the arrangement of fly-wheel and bearings.

Now let the fly-wheel of such a gyrostat be rapidly rotated, and the
gyrostat be hung up, as shown in this other diagram (Fig. 14), with the
plane of the fly-wheel vertical, and a weight attached to one extremity
of the axis. The gyrostat is not tilted over, but begins to turn round
the cord by which it is suspended with a slow angular motion which
is in the direction of the horizontal arrow if the direction of rotation
is that of the circular arrow shown in the case. The same thing is
shown by the experiment I now make. I spin this gyrostat, and hang
it with the axis of rotation horizontal by passing a loop of cord round
one end of the axis so that the weight of the gyrostat itself forms the
weight tending to tilt it over about the point of suspension. The

Fig. 13.

718

Professor Andrew Gray

[April 29,

axis of rotation here again remains nearly horizontal, but turns slowly
round in a horizontal plane as before.

The explanation in general terms is this. The weight gives a
couple tending to turn the gyrostat about a horizontal axis at right
angles to that of rotation. This coujDle in any
short interval of time produces moment of momen-
tum about the axis specified, the amount of which
is the moment of the couple multiplied by the time,
and may be represented in direction and magnitude
by the line 0 B. This must be compounded with
the moment of momentum 0 A already existing
about the axis of rotation, and gives for the resultant
moment of momentum the line O C, which is the
direction of the axis of rotation after the lapse of the
short interval of time. The axis of rotation thus
turns slowly round in the horizontal plane, and the
more slowly the more rapidly the fly-wheel rotates.
The gyrostat in fact must have this precessional
motion, as it is sometimes called, in order that the
moment of momentum of the gyrostat about a ver-
tical axis may remain zero. That it must remain
zero follows from the fact that there is no couple
in a horizontal plane acting on the gyrostat.

Thus any couple tending to change the
direction of the axis in any plane produces a
turning in a perpendicular plane. For ex-
ample, if a horizontal couple, tliat is about a
vertical axis, were applied to the axis of the
gyrostat in the last figure it would turn about a horizontal axis, that
is, would tilt over.

Again, consider a massive fly-wheel mounted on board ship on a
horizontal axis in the direction across the ship. The rolling of the
ship changes the direction of the axis, and produces a couple applied
by the fly-wheel to the bearings, and an equal and opposite couple
applied by the bearings to the fly-wheel. I'his couple is in the plane
of the deck, and is reversed with the direction of rolling, and has its
greatest value when the rate of turning of the ship is greatest. Thus
the force on one bearing is towards the bow of the ship, the force on
the other towards the stern, during a roll from one side to the other ;
and these forces are reversed daring the roll back again. This is the
gyrostatic couple exerted on its bearings by the armature of a dynamo
on shipboard.

In the same way when a gyrostat is embedded in a medium and the
medium is moving so as to change the direction of the axis of rota-
tion, a couple acting on the medium in a plane at right angles to the
plane of the direction of motion is brought into play. To fix the
ideas, think of a row of small embedded gyrostats along this table, with
their axes in the direction of the row, and their fly-wheels all rotating

Fig. 14.

1898.] on Magneto-Optic Botation. 719

in the same direction. Now let a wave of transverse displacement
of the medium in the vertical direction pass along the medium in the
direction of the chain. The vibratory motion of each part of the
medium will turn the gyrostatic axis from the horizontal, and there-
by introduce horizontal reactions on the medium. Again, a wave of
horizontal vibratory motion will introduce vertical reactions in the
medium from the gyrostats.

Now a wave of circular vibrations, like those we liave already
considered, passing through the medium in the direction of the chain,
could be resolved into two waves of rectilinear vibration, one in which
the vibration is horizontal, and another in which the vibration is
vertical, giving respectively vertical and horizontal reactions in the
medium. The magnetisaticm of the medium is regarded as due to the
distribution throughout it of a multitude of rotating molecules, so
small that the medium, notwithstanding their presence, seems of uni-
form quality. The molecules have, on the whole, an alignment of
their axes in the direction of magnetisation. These reactions on the
medium when worked out give terms in the equations of wave propa-
gation of the proper kind to represent magneto-optic rotation.

It is worthy of mention that the addition of such terms to the equa-
tion was made by McCullagh, the well-known Irish mathematician,
who, however, was unable to account for them by any physical theory.
The necessary physical theory may be regarded as afforded by the
mechanism which thus forms an essential part of Lord Kelvin's mode
of accounting for magneto-optic effects.

Lord Kelvin, in his Baltimore Lectures, has suggested for magneto-
optic rotation a form of gyrostatic molecule consisting, as shown in
the figure, of a spherical sheath enclosing two equal gyrostats. These
are connected with each other and with
the case by ball-and-socket joints at
the extremities of their axes, as shown
in Fig. 15. If the spherical case were
turned round any axis through the
centre no disalignment of the gyro-
stats contained in it would take place,
and it would act just like a simple
gyrostat. If, however, the case were
to undergo translation in any direction
except along the axis, the gyrostats
would lag behind, and the two-link
chain which they form would bend at
the centre. This bending would be Fig. 15.

resisted by the quasi-rigidity of the

chain produced by the rotation, and the gyrostats would react on the
sheath at the joints with forces as before at right angles to the plane
in which the change of direction of the axis takes place.

The general result is, that if the centre of this molecule be carried
with uniform velocity in a circle in a plane at right angles to the line

720

Professor Andrew Gray

[April 29,

of axes, tlie force required for the acceleration towards the centre,
and which is applied to it by the medium, is greater or less according
as the direction in which the molecule is carried round is with or
against the direction of rotation of the gyrostats. That is, the effect
of the rotation is to virtually increase the inertia of the molecule in
the one case and diminish it in the other.

These molecules embedded in the medium are supposed to be
exceedingly small, and to be so distributed that the medium may, in
the consideration of light propagation, be regarded as of uniform
quality. Lord Kelvin's last form of molecule, it may be pointed out,
if the surface of its sheath adheres to the medium, will have efficiency
as an ordinary single gyrostat as regards rotations of the molecule,

Fig. 16.— Path of the Bob of a Gyrostatic Pendulum.

As the pendulum moves, it passes from one ray to another on the
opposite side, and the direction of motion at each swing alters through
the angle between two rays. The central parts of the rays are left out.
The marking point does not pass exactly through the centre.

and efficiency likewise as regards translational motion of the centre
of the molecule. The former efficiency can be made as small as may
be desired by making the molecule sufficiently small ; the latter may
be maintained at the same value under certain conditions, however
small the molecule be made.

The lately discovered effect of a magnetic field in giving one
period of circular oscillation of a particle or another according as the
particle is revolving in one direction or the other about the direction
of the magnetic force, is connected with magneto-optic rotation.
There is a connection between velocity of propagation and frequency
of vibration, which is exemplified by the phenomena of dispersion.
In the Faraday effect, the two modes of vibration, if of the same period,
have different velocities of vibration, consequently these two modes

1898.] on Magneto-Optic Rotation. 721

of vibration must have different frequencies for the same velocity
of propagation.

The vibrations of the molecules of a gas in which the Zeeman
effect is produced by a magnetic field may be represented by the
motion of a pendulum the bob of which contains a rapidly rotating
gyrostat with its axis in the direction of the supporting wire of the
pendulum. The period of revolution of the bob when moving as a
conical pendulum is greater or less than the period when the gyrostat
is not sj^inning according as the direction of revolution is against or
with the direction of rotation.

The bob when deflected and let go moves in a path which
constantly changes its direction, so that if a point attached to the bob
writes the path on a piece of paper, a star-shaped figure is obtained.
I cause the gyrostatic pendulum here suspended to draw its path by
a stream of white sand on the blackboard placed below it, and you
see the result.

I must here leave the subject, and may venture to express the
hope that on some other occasion some one more specially acquainted
with the electromagnetic aspects of the phenomenon may be induced
to place the latest results of that theory before you.

[A.G.]

722

Annual Meeting,

[May 2,

ANNUAL MEETING,

Monday, May 2, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Annual Report of the Committee of Visitors for the year
1897, testifying to the continued prosperity and efficient management
of the Institution, was read and adopted, and the Report on the Davy
Faraday Research Laboratory of the Royal Institution, which accom-
panied it, was also read.

Sixty-six new Members were elected in 1897.

Sixty-three Lectures and Nineteen Evening Discourses were
delivered in 1897.

The Books and Pamphlets presented in 1897 amounted to about
260 Volumes, making, with 632 volumes (including Periodicals bound)
purchased by the Managers, a total of 892 volumes added to the
Library in the year.

Thanks were voted to the President, Treasurer, and the Honorary
Secretary, to the Committees of Managers and Visitors, and to the
Professors, for their valuable services to the Institution during the
past year.

The following Gentlemen were unanimously elected as Officers
for the ensuing year :

President — The Duke of Northumberland, K.G. D.C.L. LL.D.

Treasurer — Sir James Crichton-Browne, M.I). LL.D. F.R.S.

Secretary —Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S.
M. Inst. C.E.

Managers.
Sir William Crookes, F.R.S.
Sir Edward Frankland, K.C.B. D.C.L. LL.D. F.R.S.
The Right Hon. George Joachim Goschen, M.P,

D.C.L. LL.D. F.R.S.
Donald William Charles Hood, M.D. F.R.C.P.
Sir William Huggins, K.C.B. D.C.L. LL.D. F.R.S.
David Edward Hughes, Esq. F.R.S.
Alfred B. Kempe, Esq. M.A. F.R.S.
Hugh Leonard, Esq. M. Inst. C.E.
Thomas John Maclagan, M.D.
Ludwig Mond, Esq. Ph.D. F.R.S.
Alexander Siemens, Esq. M.Inst. C.E.
The Hon. Sir James Stirling, M.A. LL.D.
Sir Henry Thompson, F.R.C.S. F.R.A.S.
Sir Richard Everard Webster, G.C.M.G. M.P.

Q.C. LL.D.
Sir William Henry White, K.C.B. LL.D. D.Sc.

F.R.S.

Visitors.
Sir Alexander Richardson Binnie, M. Inst. C.E.

F.G.S.
Sir James Blyth, Bart. J.P.
Charles Vernon Boys, Esq. F.R.S,
Edward Dent, Esq.
James Edmunds, M.D. M.R.C.P.
Maures Horner, Esq. F.R.A.S.
Edward Kraftmeier, Esq.
Sir Francis Laking, M.D.
T. Lambert Mears, Esq. M.A. LL.D.
Lachlan Mackintosh Rate, Esq. M.A,
John Callander Ross, Esq.
William James Russell, Esq. Ph.D. F.R.S.
Sir James Vaughan, B.A. J.P.
James Wimshurst, Esq.
Alfred Fernandez Yarrow, Esq. M. Inst. C.E.

1898.] 3Ir. Edicard A. Minchin on Living Crystals. 723

WEEKLY EVENING MEETING,

Friday, May 6, 1898.

Sir William Crookes, F.PuS. Vice-President, in the Chair.

Edward A. Minchin, Esq. M.A. Fellow of Merton College, Oxford.

Living Crystals.

Crystals are a class of bodies distinguished by many remarkable
properties. Their definite symmetrical forms, limited by piano
surfaces meeting at sharp angles, in conformity with some easily
recognisable type of geometrical figure ; their peculiarities of cleavage
and etching ; their growth and individuality, most strikingly mani-
fested in their power of regeneration ; and finally, their optical
properties ; each and all of these characteristics sufficiently mark out
the crystal from the non-crystalline body. None of these qualities,
however, are in any way due to the action of life. An ordinary
crystal owes its peculiar characteristics entirely to the action of the
laws of inorganic matter, laws which admit of being clearly formu-
lated and accurately calculated.

Crystalline bodies are known, however, to occur which have been
deposited within living bodies, and which owe their origin to vital
activities. In such cases the crystal, while identical in its chemical
composition and molecular structure with crystals of inorganic origin,
may exhibit at the same time certain peculiarities which are due
entirely to the circumstances of its origin. In this way an oppor-
tuiiity is afforded of making an interesting and important comparison.
On the one hand we have the inorganic crystal, owing its striking
properties to the action of j^hysical laws which can be defined, cal-
culated and artificially reproduceil. On the other hand we have the
living crystal, as it may be termed (" biocrystal " Haeckel), which
exhibits certain additional features, the result of its origin amidst
conditions which no one has succeeded as yet in imitating or explain-
ing. Ti^e resemblances between the two kinds of crystal are such as
are due to the intrinsic properties of the material composing them ;
the differences must therefore be the effect of differences in the sur-
roundings in which the crystals arise. In other words, those points
in which a living crystal differs from a crystal of the same kind, but
of inorgiinic origin, must depend on the different activities of living
and lifeless matter. Hence a careful examination of the peculiarities
of the living crystal might be expected to throw considerable light
upon the nature of life and the properties of living matter.

As an instance of p. crystalline body which occurs both as an
inorganic substance and as a living crystal, we may take calcite,

724 Mr. Edward A. Minchin [May 6,

sufficiently well known as a mineral, and forming also the skeleton of
many forms of animal life. In the latter condition it can be well
studied in the very simple group of organisms known as Ascons, the
most primitive order of calcareous sponges.

In Ascons, as in other calcareous sponges, the skeleton is made up
of minute splinters or spicules of calcite, which always conform to one
of three types of form ; (1) rod-like or needle-shaped spicules, usually
more or less curved, and always with unlike ends ; (2) three-rayed or
triradiate spicules, having each three rays meeting at a central point ;
and (3) four-rayed or quadriradiate spicules, consisting each of a
basal system of three rays, exactly similar to the triradiate spicules,
and an additional or fourth ray tacked on to it. The three basal rays
may therefore be termed the triradiate system in the three-rayed and
four-rayed spicules alike, irrespective of the presence or absence of
the fourth ray.

With regard to the triradiate systems, it may further be noted
that three classes can be distinguished amongst them. Sometimes the
three rays are unequal in size, and irregular in arrangement, making
a figure which is quite asymmetrical ; such forms are, however, com-
paratively rare. More usually the triradiate systems exhibit a definite
symmetry which follows one of two patterns. In the first place, the
rays may meet at equal angles, so that, irrespective of the unequal
development of the rays themselves, the spicule is symmetrical about
three planes. In the second place, the angles may be such that the
spicule shows a marked bilateral symmetry, having an unpaired
and two paired angles, with corresponding unpaired and paired rays.
Thus irregular, regular and sagittal forms of the triradiate system
can be distinguished, each of which may have an extra ray tacked
on, and so become quadriradiate. The fourth ray may be straight
or curved, long or short, smooth or spined, but all its variations
are quite independent of the variations of the rays of the basal
system.

Although the spicules of Ascons often exhibit very definite and
symmetrical patterns, it is obvious that their forms do not in the least
resemble those of the inorganic calcite crystal, and from their outward
appearance it would be impossible even to suspect them to have any-
thin f^ in common with the calcite crystal. In fact, several features
seen in the spicules in question are the exact opposite of those charac-
teristic of crystals. Few things are so remarkable in crystals as the
fact that their parts are so connected together that one part cannot
vary independently of other parts, a property well seen in the laws
reo'ulatiug the addition of new faces during growth. But in the
spicule any part can vary independently of the rest. The rod -like
forms always have the two ends unlike ; the triradiate may have all
the rays unlike, and of different sizes ; and it is the rarest thing to
find a quadriradiate with the apical ray similar to the basal rays.

In spite of their remarkable divergence from the usual crystalline
form, however, it is easy to prove not only that the spicules are

1898.] on Living Crystals. 725

crystals, but also that each one is a single crystal, a fact discovered
independently by Sollas and Ebner. Their crystalline nature is
shown both by their beLaviour to polarised light and by etching
experiments. They do not answer to the cleavage test so satisfac-
torily, probably on account of the organic matter with which their
substance is interpenetrated. But other tests show them to be true
calcite crystals, distinguished, how^ever, by a peculiar form, which
can best be illustrated by imagining each spicule to have been, as it
were, cut by a lapidary out of a single block of crystal^ just as a
diamond is cut into a faceted form which is not that of the natural
diamond crystal. This comparison must only be taken as an illusti-a-
tion, however, and not as a description of how the spicule is formed,
for it is not carved out of a block, but is built up to its shape, just as
a stone house is not hewn out of solid stone, but built up of separate
stones.

It is seen that the great difference between the living and the
lifeless crystal is one of external form. In view of the regularity
and symmetry of the calcite crystal, and the very precise geometrical
laws that govern its form, the differences in this respect exhibited
by the living crystal become very striking. It is evident that some
disturbing influence must be at work which interferes with the natural
development of the crystal. We know that if a calcite crystal deve-
lops of itself, it assumes a certain form. In order to discover what
has caused the living crystal to take on its curious and unusual
growth, we must examine the conditions under which it has arisen.
Hence it is now necessary to leave for a moment the crystalline aspect
of these spicules and look at them from another j)oint of view, as
portions of a living body. To do this we must understand something
of the animal which has produced them and the part which they play
in its internal economy.

The simplest calcareous sponge or Olynthus is an organism very
easy to understand. It can be compared to a thin-walled vase, with
a wide opening at the top, and a great many minute openings or pores
on the sides. During life an internal mechanism produces a current
of water which flows in through the pcres into the cavity and passes
out by the opening or osculum at the summit. All calcareous sponges
start life in this condition, and the form and structure, whatever it
may be, which they have when full grown depends simply on the
manner in which the Olynthus grows. Hence this organism may be
considered as representing probably the primitive type of sponge
which was the ancestor of the whole group, and which is not found
anywhere at the present day as an adult form, but occurs always in
the life-history as a transitory stage, in which the structure of the
sponge is found reduced to its simplest terms.

Now the wall of the young sponge is very thin and delicate, and
could not support itself were it not for the spicules which stiffen it.
When the body wall is examined more closely it is seen that the

Vol. XV. (No. 92.) 3 b

726 Mr, Edward A, Minchh [May 6,

form and arrangement of the spicules have a definite relation to its
structure. In the simplest cases only triradiates are present, and
then they are arranged in a single layer, all placed with one ray
pointing downwards, away from the opening at the top. The rays
of different spicules overlap and cross one another, and so produce a
sort of lattice-work, with meshes rather like a honeycomb. In the
meshes are placed the pores, and at first the arrangement is such
that there are the same number of pores and spicules, the result
being that each spicule has a pore in each of the interspaces between
the arms. As the sponge grows, however, new pores and new spicules
are constantly being formed, so that the simple arrangement is upset
to some extent, though the same general pattern can be made out.
When an extra fourth ray is added on to the triradiate system, it is
always placed so as to project into the cavity, and if the extra ray
is curved, it always points up towards the large opening at the top.
If simple needle-shaped spicules are present thev are always placed
on the outside, with the straight portion of the shaft embedded in the
wall, and the curved portion sticking out into the water.

The relation of the spicules to the structure of the sponge shows
that they have a definite function to perform and an important part
to J)lay in the economy of the organism that has produced them.
Their function is partly one of support, partly one of protection.
Given a vase-like organism, with a thin porous wall, what are the
architectural requirements of a supporting and protecting framework
for it, supposing that for the material of the framework rods of cal-
cite are to be employed ? The simplest solution of the problem would
be to place the rods in the body wall, so that one or more come to lie
between each of the pores. Such an arrangement would, however,
be far from jierfect, since on the one hand a skeleton of loose uncon-
nected rods is not very strong, and on the other hand it does not
afford any protection. Hence the next stej) in the evolution of the
framework is, on the one hand, to bend some of the rods so that
they point outwards, and so cover the outside with a forest of sharp
spikes ; and, on the other hand, to join up some of the loose rods in
the wall and unite them into composite systems. Now of all the
systems that could be devised by joining rods together, none could
be more suited to the type required than the triradiate figure pro-
duced by joining three rods only. In the first place each triradiate
corresponds perfectly to the natural interspaces between the pores,
which if disposed so as to best economise sj)ace, take on an arrange-
ment m alternating rows, so that each pore is surrounded by six others
at equal distances, forming a hexagon. In short, the arrangement of
the pores repeats the familiar problem of the angles of the cells of
the honeycomb, and the triradiate spicules correspond exactly to the
interspaces. Secondly, it must be remembered that the sponge has
to live in waves and currents, and its framework requires a certain
amount of flexibility as well as strength. This condition also is best

1898.] on Living Crystals. 727

fulfilled by the triradiate systems, which, while supporting the wall,
allow it a great deal of freedom to bend and yield under the action
of powerful currents. Were the rods united into more extensive
systems, however, so as to form lattice plates or a continuous trellis-
work, we should get a framework of greater strength but of dangerous
brittleness, unable to withstand any violent shock. It is easy to
understand, therefore, the evolution of the curved, rod-like spicules
on the one handj and the triradiate systems on the other. The next
problem is to plan out a scheme of defence for the inner surface like
the palisade with which the exterior is defended. This, of course, is
easily done by making some of the rods j)roject into the interior. But
for reasons of internal economy it would be inconvenient for the
spikes on the inner surface to slant out from it like those outside.
Considerations of interior comfort require here that the spikes should
start straight out from the wall, even though they curve at their tips.
Now the spikes require support, and this cannot be obtained in the
soft wall of the sponge, too thin to hold firmly a sjDicule stuck at
right angles to its surface. These difficulties are overcome, however,
by the upright spike being stuck on to the triradiate system, and
this done, the result is at once a quadriradiate spicule, a great addition
to the strength and stability of the sponge structure. For, in the
first place, the quadriradiates constitute a formidable armament to
obstruct the entrance of intruders. In the second place they fit in,
so to speak, with a method by which the sponge is accustomed to
protect itself against hard times. When exposed to unfavourable
conditions, Ascons contract themselves very greatly and so become
much more rigid, since their wall becomes much thicker and their
cavity much smaller, sometimes vanishing altogether. When a
sponge with quadriradiate spicules contracts to a certain point, the
projecting rays interlock in the interior of the cavity, and, in this
way the fragile organism attains a much greater rigidity and power
of resistance to the action of external forces.

It is thus seen that the three classes of spicules are just those
which are best fitted for supporting and protecting an organism
having the structure of the simple sponge or Olynthus, which has
been described. But this process of adaptation can be traced still
further. It has already been pointed out that the symmetrical tri-
radiate systems can be divided into two classes, sagittal and regular.
To understand the significance of these two forms it is necessary to
glance at the further growth of the Olynthus.

In Ascons, the primitive vase-like organism elongates, while at
the same time its wall becomes folded and bulged out to form hollow
outgrowths, each like the finger of a glove. The outgrowths con-
tinue to increase in length and become branched, and finally join
together so that a network of hollow tubes is formed, clustered round
the primitive osculum of the Olynthus, and also giving rise to new
oscula of the same kind, which rise up from the network like

3 B 2

728 Mr. Edward A. Minchin [May 6,

chimneys. In this peculiar growth two distinct types are found.
In one type (Clatlirina) the tubes form a close network opening by
a few short oscula, usually very inconspicuous. In the other type
(Leucosolenia) the sponge has a more erect form and consists chiefly
of the conspicuous chimneys, united by an inconspicuous network of
small tubes. Now in the former type of architecture the pressures
and strains in the network of tubes are dilferent at different spots,
and cannot be said to predominate in one direction more than another.
Hence, in ClatLrina, we might expect to find a type of spicule adapted
to these conditions, and as a matter of fact, the predominant spicule
here is the triradiate with equal rays and equal angles : that is to say,
an evenly balanced form fitted to resist tensions in any direction
equally. But occasionally a Clathrina grows in a more erect and
stalked form, and then strains in a vertical direction predominate ;
in such a case (e.g. CI. hlanca, CI. lacunosa) the arm of the spicule,
which is placed vertically, becomes greatly strengthened, especially
in certain regions, the other two arms remaining small, sometimes very
much so. In all cases, however, the equal angles are still retained.

In Leucosolenia, on the other hand, the erect growth requires
strengthening chiefly in a vertical direction, and the form of the
triradiate spicule is at once seen to correspond with this, having
paired angles and a form which at once suggests adaptation to pressure
in one direction rather than another. The spicules are placed with
great regularity, the unpaired ray directed vertically, and the paired
rays horizontally, so that the whole forms a beautiful basket-work,
stiffened by vertical ribs and held together by horizontal girders. It
is thus seen that even subordinate peculiarities of form have their
special uses, which are evident when studied in connection with the
architectural requirements of the whole organism.

The result, therefore, of an inquiry into the relations between
the living crystals and the organism by which they are formed, is
as follows: that both in their form and arrangement the spicules
represent a most exquisite piece of engineering, and are to be re-
garded as adapted to support and protect the fragile and delicate
body wall. Moreover, the history which has been traced for the
development of the spicules is shown to be not altogether imaginary
by the facts of the development of the spicules, which may now be
briefly considered.

The calcareous spicules are formed within cells, derived from the
external layer of the body wall, but each ray or branch owes its
origin to a distinct cell. In the simplest case one cell forms a single
rod-like spicule, and when a very large rod is to be formed, the
mother cell may multiply into two or more daughter cells. When
a triradiate is to be formed, three mother cells come together, one
for each ray, and after each has divided into two daughter cells, they
secrete three separate rods, which sooner or later become joined to-
gether to form the spicule. When a quadriradiate is to be formed,

1898.] on Living Crystals. 720

a remarkable series of events takes place. First, three cells come
together and form a triradiate system in the usual way. Then a
cell is given oif by the division of the nearest pore cell, and this
cell travels to the little triradiate spicule and takes up a position
over it, on its inner side. Then the cell secretes a little rod of
calcite, which is stuck on to the triradiate system, converting it into
a four-rayed spicule, so that not only is the fourth ray a late addition
to the basal system, but it is derived from quite a different source,
the basal rays being formed by cells of one class, the fourth ray by
a cell of a different class. The development of the triradiate and
quadriradiate spicules shows them, in fact, to be composite bodies,
built up of a number of skeletal elements, each a simple rod. This
is remarkable, and even paradoxical, in view of the fact already men-
tioned, that each spicule, when full grown, is a single crystal. In
their earliest stages, however, it is found that the minute triradiate
systems are at first non-crystalline, and only become so after the
rays have been joined together. Then, since all parts are in con-
tinuity, the crystallisation takes place in such a way that all parts
of the spicule have a uniform molecular arrangement, producing not
three or four separate crystals, as might at first sight have been
expected, but a single one.

It is seen, therefore, that the primitive skeletal element in Ascons
is a simple rod, and that the general course of evolution was such as
has been traced out, some rods remaining single but growing out from
the surface ; others becoming arranged in trios and forming triradiate
systems ; and others, again, becoming tacked on to the triradiates to
form the four-rayed spicules. But how did the primitive skeletal
elements, the rods, themselves originate ? Unless an intelligible origin
can be suggested for them, there is a gap in the scheme of evolution.
Now any living organism, however simple, is composed of matter
which is in process of constant change and transmutation. As a
result of metabolism, substances of all kinds are continually being
formed, and amongst them many of crystalline nature, which may be
deposited from a state of solution and crystallise out. Hence it is
not uncommon to find ordinary crystals in living tissues, crystals
which show no sign of having any origin at all out of the common,
and which must be supposed either to be of no use to the organism
that produced them, or at least to perform some function for which
their external form is not of great importance. It is a rational sup-
position, therefore, that the spicules of Ascons also had at one time the
form as well as the constitution of crystals, and originated simply as
bye-products, so to speak, of the wear and tear of the living substance.
When, however, it became of importance to the organism that they
should have one form rather than another, then their natural form
became modified and completely altered. Now this is the most
obscure portion of all their history, how, namely, the living substance
can so act upon the growing crystal as to cause it to assume a form

730 3Ir. Edivard A. Minchin [May 6,

whicli is not that which it would naturally assume. We can observe
that it does so, and that not only in this, but in many other cases,
living bodies appear to have the power of modifying and transforming
their component materials in a way which we are far from under-
standing. Ko sooner, however, is this mysterious change effected
than the crystal has crossed, so to speak, the line which separates the
living from the lifeless world, and must now be regarded from an
entirely different standpoint, that is to say, as a part of a living body.
As such it is subject to new influences and is governed by new laws,
which, as it were, override those by which the lifeless crystal is ruled.
In the first place, it must be supposed that each spicule, had it been
deposited in an inorganic matrix, would have had the characteristic
contours of an ordinary crystal of calcite. This receives, in fact,
further proof from the interesting observations of Sollas, who showed
that upon sponge spicules j^laced in a solution of carbonate of lime,
new layers of calcite are deposited, which tend to restore the ordinary
crystalline form. Instead of that, however, it has a form which can-
not be brought into any relation with its intrinsic crystalline prof»er-
ties. It is true that the attempt has been made to ex]3lain the
symmetry often exhibited by the spicules as due to their crystalline
nature. Not only, however, can any such explanation be shown to be
inadequate in itself, but it is also quite unnecessary, since in other
sponges, spicules even more symmetrical may occur, which are manu-
factured, so to speak, out of a non-crystalline material, namely, colloid
silica. The symmetry and regularity of form which sponge spicules
often possess are clearly, therefore, not due to the inherent properties
of the material of which they are composed, but to the action of the
living matrix in which they are deposited. The symmetry of a
crystal, on the other hand, is one wdiich in its fundamental traits is
entirely independent of the matrix in which it is dei)osited. We
have seen further that in a natural crystal the parts cannot vary
independently. But in the living crystals every part varies indepen-
dently of all the others, according to the needs of the organism, and
the spicules can be traced through a long series of evolutionary
changes, resulting in the many different forms with which we are
acquainted.

We may therefore sum up with regard to these living crystals
as follows. Their constitution is that of the calcite crystal, but
their external form is that which the sponge requires, and not that
which they would naturally assume. They furnish us, in fact, with
a beautiful instance of what is termed adaptation, that is to say, the
fact that any living organism tends to have just that form, structure
and organisation in all its parts which it requires in order to main-
tain its existence in its peculiar mode of life, whatever it may be.

The principle of adaptation raises many scientific and philosophical
questions of great importance, but certain points may be emphasised
which have been seen in the instances under discussion. In the first

1898.] on Luing Crystals, 731

place, it is very evident that these adaptations did not come into
existence suddenly, like an instantaneous pliotograph as it were, but
are the result of a long and gradual course of evolution from the
simple crystal, formed, so to speak, almost by chance in the molecular
ferment and turmoil that goes on in the living organism, up to the
highly perfected and elaborated forms of spicules which compose
the supporting framework in different species of sponges. In the
second place, the persistence of different species of sponges in certain
grades of evolution shows that the adaptation in any given case is
not to be regarded as perfect, but only as slightly better or worse
than that seen in other species. This points to the main factor in
the evolution having been the natural selection consequent upon
competition and the struggle for existence.

[E. A. M.]

732 General Monthly Meeting. [May 9,

GENERAL MONTHLY MEETING,

Monday, May 9, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer aud
Vice-President, in the Chair.

The following Vice-Presidents for the ensuing year were
announced : —

Sir William Crookes, F.R.S.

Sir Edward Frankland, K.C.B. D.C.L. LL.D. F.E.S.
Sir William Huggins, K.C.B. D.C.L. LL.D. F.R.S.
Ludvvig Mond, Esq. Ph.D. F.R.S.
The Hon. Sir James Stirling, M.A. LL.D.
Sir Henry Thompson, F.R.C.S. F.R.A.S.
Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer.
Sir Frederick Bramwell, Bart. D.C.L. LL.D. F.R.S. Honorary
Secretary.

Hugh Bell, Esq.

Henry Marc Brunei, Esq. M. Inst. C.E.

Bailey Knight, Esq.

Lionel Phillips, Esq.

Alfred Morton Smale, Esq. M.R.C.S.

were elected Members of the Royal Institution.

The Right Hon. Lord Rayleigh was re-elected Professor of
Natural Philosophy in the Royal Institution.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

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1897.
Monumental Remains of the Dutch East India Company in Madras. By A. Rea.

4to. 1897.
Accademia dei Lincei, Reals, Boma — Classe di Scienze Fisiche, Matematiche e

Naturali. Atti, Serie (^liuta : Rendiconti. 1° Semestre, Vol. VII. Fasc. 7, 8.
Asiatic Society, Boyal — Journal for April, 1898, 8vo.

Astronomical Society, Royal — Monthly Notices, Vol. LVIII. No. 5. 8vo. 1898.
Boston Public Library— Monthlj Bulletin, Vol. III. No. 4. 8vo. 1898.
Bright, Charles, Esq. F.R.S. E. {the Author)— Science and Engineering, 1837-97.

8vo. 1898.
British Arcliitects, Royal Institute o/— Journal, 3rd Series, Vol. V. Nos. 11, 12.

4to. 1898.
Cambridge Philosophical Society — Transactions, Vol. XVI. Part 4. 4to. 1898,
Camera Club — Journal for April, 1898. 8vo.
Chemical Society — Journal for April, 1898. 8vo.
Proceedings, No. 198. 8vo. 1897.

1898.] General Monthly Meeting. 73^

Chicago, John Crerar Library — Third Annual Eeport. 8vo. 1898.

Civil Engineer?:, Im^titution of — Minutes of Proceedings, Vol. CXXXI. 8vo. 1898.

Cracovie, Acade'mie des Sciences — Bulletin, 1898, No. 2. 8vo.

Editors — American Journal of Science for April, 1898. 8vo.

Analyst for April, 1898. 8vo.

Antliony's Photographic Bulletin for April, 1898. 8vo.

Astro-physical Journal for April, 1898. 8vo.

Athenaeum for April, 1898. -ito.

Author for April, 1898. 8vo.

Bimetal! ist for April, 1898. 8vo.

Brewers' Journal for April, 1898. 8vo.

Chemical News for April, 1898. 4to.

Chemist and Druggist for April, 1898. 8vo.

Education for April, 1898.

Electrical Engineer for April, 1898. fol.

Electrical Engineering for April 15, 1898. 8vo.

Electrical Review for April, 1898. 8vo. .

Electricity for April, 1898. 8vo.

Engineer for April, 1898. fol.

Engineering for April, 1898. fol.

Homoeopathic Review for April, 1898. 8vo.

Horological Journal for April and May, 1898. 8vo.

Industries and Iron for April, 1898. fol.

Invention for April, 1898.

Journal of Physical Chemistry for February, March and April, 1898. 8vo.

Journal of State Medicine for April, 1898. 8vo.

Law Journal for April, 1898. 8vo.

Lightning for April, 1898. 8vo.

Machinery Market for April, 1898. 8vo.

Nature for April, 1898. 4to.

New Church Magazine for April, 1898. 8vo.

Nuovo Cimento for Feb. 1898. 8vo.

Photo<.'raphic News for April, 1898. 8vo.

Physical Review for March, 1898. 8vo.

Public Health Engineer for April, 1898. 8vo.

Science Siftings for April, 1898.

Travel for April, 1898. 8vo.

Tropical Agriculturist for April, 1898.

Zoophilist for April, 1898. 4to.
East India Association — Journal, Vol. XXX. No. 13. 8vo. 1898.
Electrical Engineers, Institution of — Journal, Vol. XXVII. Nos. 133, 134. 8vo.

1898.
Ellis, G. B. Esq. Cthe Author)— The Merchandise Marks Act. 8vo. 1898.
Florence, Bihlioteca Nazionale Centrale — Bolletino, Nos. 295, 296. 8vo. 1898.
FranMin Institute — Journal for April, 1898. 8vo.
Gall and Inglis, Messrs. {the Publishers) — The Observer's Atlas of the Heavens.

By W. Peck. 4to. 1898.
Geneva, Societe de Physique et d'Histoire Naturelle—Com-ptea Rendus, 1885 et

seq. 8vo.
Geographical Society, Royal — Geographical Journal for April, 1898. 8vo.
Geological Society — Quarterly Journal, No. 214. 8vo. 1898.
Goteborgs Hogshola — Arsskrift, Band III. 8vo. 1897.
Harlem, Societe Hollandaise des Sciences — Archives Neerlandaiscs, Ser. II.

Tome 1, Livr. 4, 5. 8vo. 1898.
Head, A. P. Esq. M.I.M.E. (the Author)— 'Notes on American Iron and Steel

Practice. Svo. 1898.
Horticultural Society, Eoijal— J onvna,\. Vol. XXI. Part 3. Svo. 1898.
Imperial Institute — Imperial Institute Journal for April, 1898.
Iron and Steel Institute — Journal. Name Index, Vols. I.-L. Svo. 1898,

734 General Monthly Meeting. [May 9,

Johns HopMns University — University Circulars, No. 134. 4to. 1898.

American Chemical Journal, Jan. -April, 1898. 8vo.
Jordan, Wm. L. Esq. (the Author)— The Standard of Value. 7tli ed. 8vo. 1896.
Kerntler, Franz, Esq. (the Author) — Die Moglichkeit eiiier experimentellen

Entsclieidung zwischen den verschiedenen elektrodynamischen Grundge-

setzen. 8vo. 1898.
Kew Observatory, Director — Eeport on Kew Observatory, 1897. 8vo. 1898.

Notes on Thermometry. By C. Chree. 8vo. 1898.
Linnean Societij— Journal, Nos. 169, 170, 231. 8vo. 1898.

London County Council Technical Education Board — London Technical Educa-
tion Gazette for March, 1898. fol.
Middlesex Hospital— ReTpovts for 1896. 8vo. 1897.
Microscopical Society, Royal — Journal, 1898, Part 2. 8vo.
Munich, Royal Bavarian Academy of Sciences — Abhandlungen, Math.-Phvs. Classe,

Band XIX. Abth. 2. 4to. 18!t8.
Festrede, 14 Nov. 1896. 4to. 1897.
Navy League — Navy League Journal for April, 1898. 8vo.
New Zealand, Registrar-General of — Statistics of the Colony of New Zealand for

1896. 8vo. 1897.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLVI. Part 6 ; Vol. XLVII. Parts 2, 3. 8vo. 1898.
Borings and Sinkings, XJ-Z. 8vo. 1898.
Ohach, Br. Eugene F. A. M.R.L (the Author)— Guita Percha (Cantor Lectures).

8vo. 1898.
Fharmaceutical Society of Great Britain — Journal for April, 1898. Svo.
Rome, Ministry of Public Works — Giornaie del Genio Civile, 1897, Fasc. 11°, 12°;

1898, Fasc. 1. 8vo. 1897-98. And Designi. fol.
Roijal Irish ^ca(Ze?7zy— Transactions, Vol. XXXI. Parts 1-6. 4to, 1896-98.
Royal Society of London — Philosophical Transactions, Ser. A. Vol. CXCI. Nos.

214, 215 ; Ser. B. Vol. CLXXXIX. Nos. 154-156. 4to. 1898.
Proceedings, Nos. 390-392. Svo. 1897.
Sanitary Institute — Journal, Vol. XIX. Part 1. Svo. 1898.
Selborne Society — Nature Notes for April, 1898. Svo.
Sidgreaves, Rev. Father, F.R.A.S. — Results of Meteorological and Magnetical

Observations at Stonj'hurst College Observatory, 1898. Svo. 1898.
Smiths^onian Institution — Bibliography of the Metals of the Platinum group :

Platinum, Palladium, Iridium, Khodium, Osmium, Ruthenium, 1748-1896.

By J. L. Howe. Svo. 1897. (Smith. Misc. Coll.)
The Smithsonian Institution, 1846-96. The History of its first Half Century.

Edited by G. B. Goode. Svo. 1897.
Society of Arts — Journal for April, 1898. Svo.
Statistical Society, i^oyaZ— Journal, Vol. LXI. Part 1. Svo. 1898.
Stewart, Charles, Esq. (the Author) — Stewart's Telegraphic Code. Svo. 1897.
Sweden, Royal Academy of Sciences — Handlingar (Me'moires), Band XXIX. 4to.

1896-97.
United Service Institution, Royal — Journal for April, 1898. Svo.
United States Patent Office — Annual Report of the Commissioner of Patents for

1896. Svo. 1897.
Official Gazette, Vol. LXXXII. No. 13; Vol. LXXXIII. No. 1. Svo. 1898.
Upsal, V Observatoire Meteorologique — Bulletin Mensuel, 1897. 4to. 1897-98.
Victoria Institute — Journal, No. 119. Svo. 1898.
Zoological Society of London — Report for 1897. Svo. 1898.

1898.] Prof. W. A. Tilden on Experiments on Certain Elements. 735

WEEKLY EVENING MEETING,

Friday, May 13, 1898.

LuDWiG MoND, Esq. Ph.D. F.R.S. Vice-President, in the Chair.

Professor W. A. Tilden, D.Sc. F.R.S.

Becent Experiments on Certain of the Chemical Elements
in relation to Heat.

The discovery that different substances have different capacities for
heat is usually attributed to Irvine, but there can be no doubt that
Black, Crawford and others contributed to the establishment of the
idea. The fact that equal weights of different substances, in cooling
down through the same number of degrees, give out different amounts
of heat, may be illustrated by the well-known experiment, in which
a cake of wax is penetrated with different degrees of rapidity by
balls of different metals heated to the same temperature. But, for
the quantitative estimation of the amounts of heat thus taken up and
given out again — that is, the specifiG heats — the physicist must resort
to other forms of experiment, each of which presents difficulties of
its own. Broadly speaking, three principal methods have been used
in the past for this purpose. The first is based upon the observation
of the exact change of temperature j^roduced in a known mass of
water, by mixing with it a known weight of the substance previously,
at a definite temperature above or below that of the water. The
second consists in determining the quantity of ice melted, when the
heated body is brought into contact with it in such a way that no
heat from any other source can reach the ice. And the third method
consists in observing the rate at which the temperature of the heated
body falls through a definite range of degrees, when suspended in a
vacuous space, as compared with the rate of cooling of another body
taken as the standard.

The process of intermixture with water w^os used by the earlier
experimenters in the last century, and some of the best results extant
have been obtained by this method, which, however, is not so easy
as it appears when the highest degree of accuracy is desired.

Lavoisier and Laplace, in 1780, devised the ice calorimeter which
bears their name ; and in a most interesting memoir, which is re-
printed among Lavoisier's works, they show that they were familiar
with the idea which in modern times is expressed as the principle
of the conservation of energy. In this memoir they give the results
of experiments, in which the specific heats of iron, mercury and a

736

Professor W. A. Tilden

[May 13,

few other substances are estimated with a very tolerable approach to
accuracy. Although many of the metals were known to them, and
supposing they had persisted in this work, it would not have been
possible for them to make the discovery which was reserved for
Dulong and Petit thirty-five years later, for the atomic theory had
not then been conceived, and no elemental combining proportions
had been determined.

Dulong and Petit * seem to have used at first the method of mix-
tures, and to have found, by direct exiDcriment, that the specific heat of
solids (metals and glass) increases with the temperature. They also
studied (after Leslie) the laws of cooling of bodies ; and two years
after the publication of their first paper on the subject, they (Petit
and Dulong, sic) arrived at the remarkable general expression which
is associated with their names.f

After pointing out that all the results of previous experiments
except those of Lavoisier and Laplace are extremely incorrect, they
describe their own conclusions obtained by the method of cooling,
conducted with many precautions to avoid error. The numerical
expression of their experimental results is given in the following
table : —

Copt of Table by Petit and Dulong.
(Ann. Cliim. Phys. 1819, x. 403.)

Specific Heats.

Atomic Weights Atoi
(0 = 1). X Sp

nic Weight
ecific Heat,

Bismuth

•0288

13-30

3830

Lead

•0293

12-95

3794

Gold

•0298

12-43

3704

Platinum

•0314

11-16

3740

Tin

•0514

7-35

8779

Silver

•0557

G-75

3759

Zinc

•0927

4-03

3736

Tellurmm

•0912

4-03

3675

Copper

•0949

3-957

3755

Nickel

•1035

3-69

3819

Iron

•1100

3-392

3731

Cobalt

•1498

2-46

3685

Sulphur

•1880

2-011

3780

The statement of the relation indicated in the last column of
figures is expressed in the following words of the authors, p. 405 :
" Les atomes de tous les corps simples ont exactement la memo
capacite pour la chaleur."

Here the question rested, till resumed many years later (1840) by
Eegnaultj who in his first memoir | pointed out the difficulties which

Ann. Chira. 1817, vii. 144. f Ibid. 1819, x. 395.

Ibid. 73, 5.

1898.] on Experiments on Certain Elemeuts in relation to Heat. 737

attend the acceptance of the statement of Petit and Dulong in the
form in which they gave it. He then discussed the three principal
experimental methods : viz. (1) fusion of ice ; (2) mixture with water
or other liquid ; and (3) cooling ; and decided in favour of the
second, which he used throughout his researches. The general form
of the apparatus used by the great physicist has been a model for
the guidance of successive experimentalists since his time.

Another quarter of a century elapsed before the question of the
specific heats of the elements was resumed by Hermann Kopp. His
results were communicated to the Royal Society, and are embodied
in a paper printed in the ' Philosophical Transactions ' for 1865. After
reviewing the work of his predecessors, he described a process by
which he had made a large number of estimations of specific heat,
not only of elements, but of compounds of all kinds in the solid state.
Concerning his own process, however, he remarks that " The method,
as I have used it, has by no means the accuracy of that of Regnault "
(p. 84).

In 1870 Bunsen introduced his well-known ice calorimeter. This
is an instrument in which the amount of ice melted by the heated
body is not measured by collecting and weighing the water formed,
but by observing the contraction consequent upon the change of
state. The results obtained by Bunsen himself are uniformly slightly
lower than those of Regnault for the same elements.

Since that time, experiments have been made by \A'eber, Dewar,
Humpidge and others, in connection especially with the influence of
temperature in particular cases.

. Setting aside the elements, carbon, boron, silicon and beryllium,
as providing an entirely separate problem, the question is whether the
law of Dulong and Petit is strictly valid when applied to the metals.
Kopp, in the discussion of his subject, came to the conclusion that it
is not ; but the grounds for this conclusion are unsatisfactory, since
neither the atomic weights nor the specific heats were at that time
known with sufficient accuracy. It has been customary to assume
that the divergences from the constant value of the product, At. Wt.
X Sp. Ht., are due partly to the fact that at the temperature at which
specific heats are usually determined, the different elements stand in
very different relations to their point of fusion : thus, lead at the tem-
perature of boiling water is much nearer to its melting point than
iron under the same conditions. The divergences have also been
attributed to temporary or allotropic conditions of the elements. As
to the relation to melting point, the specific heats of atomic weights
seem to be practically the same in separate metals and alloys of the
same which melt at far lower temperatures. For example, the atomic
heat of cadmium is 6 * 85 ; of bismuth 6 • 47 ; of tin, 6 • 63 ; and of lead,
6*50; while the mean atomic heat in alloys of bismuth with tin and
lead with tin ranges from 6 '40 to 6*66 (Eegnault), which is practi-
cally the same. Again, while the melting point of platinum is at a
white heat, the metal becomes plastic at a low red heat, and yet tho

738

Professor W. A. Tilden

[May 13,

specific heat at this lower temperature is very little less than it is
near the melting point. The properties of many other metals,
notably zinc and copper, change considerably at temperatures far
removed from their melting points without substantial change in
their capacity for heat.

As to allotropy, it is a phenomenon which is comparatively rare
among metals, and in the marked cases in which it occurs we have
no information as to the value of the specific heats in the several
varieties, such as the two forms of antimony and the silver-zinc alloy
of Heycock and Neville, and they may be left out of account. Bunsen
compared the so-called allotropic tin, obtained by exposing the
metal to cold for a long time, and found it -054:5 against '0559
for the ordinary kind.* In dimorj)hous substances there is often no
difference. Eegnault found for arragonite • 2086 and for calcite * 2085
respectively. The differences between metals hammered and annealed,
hard and soft, were also found by Eegnault to be very small, f

Hard steel
Hard bronze

1175. Same, softened
0858. Same, softened

1165

08G2

Kopp came to the conclusion, ^rs/, that each element in the solid
state, and at a sufiicient distance from its melting point, has one sj)ecific
or atomic heat, which varies only slightly with physical conditions ; and
secondly, that each element has essentially the same specific or atomic
heat in compounds as it has in the free state. This last is practically
identical with the statement which is known as Neumann's law. With
Kopp's conclusion I agree, but, from some of Eegnault's results
coupled with my own, the effect of small quantities of carbon and
j)erhaps of sulphur upon the specific heats of metals is greater than
has been supposed. If we take the results of Eegnault and of Kopp
and combine them with the most accurately known atomic weights,
the products are still not constant.

Atomic Weights most accurately known (1897) combined
WITH Specific Heats.

Copper

Gold

Iron

Lead

Mercury liq

„ - 78° to + 10°

Silver

Iodine

63-12
195-74

55-60
205-36
198-49
198-49
107-11
125-89

S.H.

Eegnault.

09515
03244
11379
03140
03332
03192
05701
05412

S.H.

At. Ht.

Kopp.

Eegnault.

-0930

601

6-35

-1120

6-33

•0315

6-45

6-61

..

6-34

-0560

6-11

6-81

At. Ht.
Kopp.

5-87

6-23
6-47

6-00

* Pogg. Ann. 141, 27.

t Ann. Chim. [3], ix.

1898.] on Experiments on Certain Elements in relation to Heat. 739

The " Law " of Dulong and Petit is therefore only an approxima-
tion ; but this may perhaps be due to inaccuracy in the estimation of
the specific heat, owing'to impurity in the material used. That is the
problem which I have endeavoured to solve.

The introduction by Professor J. Joly of a new method of calori-
metry, which depends upon the condensation of steam upon the cold
body, and the excellent results obtained by the Author in the use of
the differential form of his instrument,* led me to think that with
due attention to various precautions — such as exact observations of the
temperatures, and practice in determining the moment at which the
increase of weight due to condensation is completed — results of con-
siderable accuracy might be obtained.

The problem is to find two elements, very closely similar in
density and melting point, which can be obtained in a state of purity,
and then to determine with the utmost possible accuracy the specific
heat of each under the same conditions.

The two metals cobalt and nickel were selected for the purpose.
They were examined by Reguault, but the metals he used were very
impure.

The cobalt employed in my experiments was prepared by myself.
For the nickel I am indebted to Dr. Ludwig Mond. Both were
undoubtedly much more nearly pure than any metal available in
Eegnault's time. The results obtained are as follows : —

Specific Heats of Cobalt and Nickel
Pure fused.

Cobalt, S.G.^, 8-718.

4c

■10310
10878
10310
-10355
10373
10362

Aritli. mean

10348

2r

Nickel, S. a ^8-790.

•10953

•10910 \ toohi^h?

•10930

10931

The value arrived at for cobalt is much lower than that ( • 1067)
derived from Regnault's experiments, while that for nickel is practi-
cally identical with Kegnault's, which is * 1092. This is certainly
too high.

Further experiments will be made. Already, however, I feel
certain that Kopp's conclusion is right, and that the law of Dulong
and Petit, even for the metals, is an approximation only, and

* Proc. R. S. 47, 241,

740

Professor W. A. Tilden

[May 13,

cannot be properly expressed in tlie words of the discoverers. For,
although the exact values of the atomic weights of these two elements,
cobalt and nickel, are not known, it is certain that they are not so far
apart as would be implied by these values for the specific heats.

Two other examples of somewhat similar kind are shown by gold
and platinum, copper and iron.

For the gold I naturally applied to my colleague, Professor
Eoberts- Austen. The platinum I prepared from ordinary foil, by re-
solution and re-precipitation as ammonio-chloride, and subsequent
heating. Both metals were fused into buttons before use. The
atomic heats come closer together than those of Co and Ni.

Copper and iron differ considerably in melting point, but both
at the temperature of 100° are far removed from even incipient
fusion. The copper was prepared from pure sulphate by electrolysis,
the iron by reduction of pure oxide in pure hydrogen. Notwith-
standing all our care, it was disappointing to find it contained • 0 1 per
cent, of carbon, the source of which I am at a loss to explain. This
iron is purer than any examined by Eegnault or Kopp.

Specific Heats op Gold and Platinum.

Pure fused.

Gold, S.G.^~, 19-227.

18°
Platinum, S.G. -10,21 -323

•03052

•03147

•03017

•03150

•03035

•03144

rith. mean .. .. -03035

Aritb. mean .. .. -0314

tomic heat ^.. .. 5-94

Atomic heat .. .. 6-05

SrEciFic Heats of Copper and Iron.

Fused.

20°
Copper (pure) S. G. ^^ 8-522.

•09248
•09241
•09205
•09234

Aritb. mean
Atomic heat

• 09232
5-83

15°

Iron, S. G. — r^, 7 '745, contains
Q-Ol per cent, copper.

11022
■11037

Aritb. mean ..
Atomic beat , .

•110.30
0^13

Tlie differences observed between cobalt and nickel, and between
gold and platinum, are manifestly not due to allotropes or to differ-

1898.] on Experiments on Certain Elements in relation to Heat. 741

ences of melting point, which in these cases can have no effect on the
result. 80 large a difference must be due to peculiarities inherent in
the atoms themselves ; and differences of atomic heat are to a certain
extent comparable with the differences observed in other physical
properties, which, like specific volume, specific refraction, &c., are
approximately additive.

If we try to think what is going on in the interior of a mass of
solid when it is heated, the work done is expended not only in setting
the atoms into that kind of vibration which corresponds to rise of
temperature, that is, it makes them hotter, but partly in separating
the molecules or physical units from one another (= expansion) and
partly in doing internal work of some kind, the nature of which is not
known. A difference between metals and non-metals has been brought
out by the researches of Heycock and Neville, who find that metals
dissolved in metals are generally monatomic ; whereas it is generally
admitted that iodine, sulphur and phosphorus in solution are poly-
atomic. It is moreover remarkable that, although in respect to specific
heat each element in a solid seems to be independent of the other
elements with which it is associated, when the elementary substances
are vaporised some rise in separate atoms like mercury, some in
groups of atoms like iodine, sulj)hur, arsenic and phosphorus, and as
the temperature is raised these groups are simplified with very vary-
ing degrees of readiness.

The two metals, cobalt and nickel, with which I began my inquiry,
have very nearly the same atomic weight, the value, 58 • 24 for nickel
and that for cobalt 58 • 49, being calculated by F. W. Clarke from the
results of a great many analyses by many different chemists. They
are so close together that for a long time they were regarded as
identical, and Mendeleef does not hesitate even to invert the order by
making Co = 58*5 and Ni = 59. These metals, nevertheless, differ
from each other in several very important chemical characters. Nickel,
for example, forms the well known and highly remarkable compound
with carbonic oxide discovered by Dr. Mond. Cobalt, on the other
hand, produces many ammino-compounds to which there is nothing
corresponding among the compounds of nickel.

Having put aside the common excuses for the observed diverg-
ences from the constant of Dulong and Petit, we are compelled to
look round for some other hypothesis to explain them.

The constitution of carbon compounds is now accounted for by a
hypothesis concerning the configuration of the carbon atom introduced
by Van't Hoff and Le Bel twenty-five years ago, and which is now
accepted by the whole chemical world. It seems not unreasonable to
apply a similar idea to the explanation of those cases of isomerism
which have been observed in certain compounds of the metals, notably
chromium, cobalt and platinum. This has already been done by Pro-
fessor Werner, of Ziirich. If the constitution of comi^ounds can be
safely explained by such hypothesis, this implies the assumption of
peculiarities in the configuration of the individual constituent metals

Vol. XV. (No. 92.) 3 0

742 Experiments on Certain Elements. [May 13,

around which the various radicles are grouped in such compounds ; and
hence peculiarities in the behaviour of such metals in the elemental
form may possibly be accounted for. For the atom of cobalt Professor
Werner employs the figure of the regular octahedron. For nickel,
therefore, which differs from cobalt in many ways, a different figure
must be chosen. This, however, is for the present a matter of pure
speculation.

W. A. T.

1898.] The Early Life and Work of Shakespeare. 743

WEEKLY EVENING MEETING,

Friday, May 20, 1898.

The Hon. Sir James Stirling, M.A. LL.D. Vice-President,
in the Chair.

The Eight Hon. D. H. Madden, M.A. LL.D.

The Early Life and Work of Shakespeare.

In the year 1592 there was in London a moderate actor and
struggling dramatist named William Shakespeare. He had as yet
published nothing, and he was known chiefly as an adapter of the
work of popular authors to the uses of the company of players with
whom he was associated. As a dramatist, few would have thouo'ht of
comparing him with Marlowe, Greene, Peele, Lodge, or Nash ; and as
a poet he was known only to some private friends, to whom he had
shown certain sonnets and, it may be, the first heir of his invention,
a poem entitled * Venus and Adonis.'

Had he then met the fate which shortly afterwards overtook his
great master, Marlowe, a tavern brawl might have dej^rived the world
not only of ' Hamlet,' ' Othello ' and ' As you like it,' but of all
knowledge of the man who was destined to be their author. It is
true that his genius had attained to the production of ' A Midsummer
Night's Dream ' and ' Romeo and Juliet ' ; but neither of these plays
was printed until some years after, when his later productions had
added to the reputation of their author. Had his fellows adventured
on the publication of a posthumous volume, containing, in addition
to these plays, * Titus Andronicus,' ' Henry VI,' ' Love's Labour's
Lost ' and ' The Comedy of Errors,' it is possible that the truer in-
stincts of the nineteenth century might have rescued the collection
from the indifference of the eighteenth century, and the contempt of
the seventeenth, when Pepys was not deterred by the fame of their
author from describing ' A Midsummer Night's Dream ' as the most
insipid, ridiculous play, and ' Eomeo and Juliet' as the worst, he had
ever seen. If Thomas Thorpe had thought it worth while to publish
the Sonnets at the instance of Mr. W. H. (which I greatly doubt), it
is possible that the discernment of an unheeded critic might discover
some of the finest poetry in the English language in the forgotten
volume — for forgotten it certainly would have been at a time when
Steevens deemed the sonnets unworthy of publication, as productions
which no one would read.

3 c Q

744 The Bight Hon. D. H. Madden [May 20,

I have suggested tliese possibilities with no intention of engaging
in the most fruitless of all inquiries — speculation as to what might
have been — but for a practical purpose. If we would clearly discern
the man Shakespeare in relation to the known facts of his life, it is
needful to close our eyes to the dazzling splendour of his later works.
I invite you to do this for a moment, and, forgetful of theories, fancies
and transcendental criticism, to fix your attention uj)on a few simple
facts, proved by clear evidence, in the hope that we may be thus aided
in the realisation of a personality, at once the most attractive and
the most elusive.

For a reason, which will appear presently, I take the close of the
year 1592 as the termination of what I have called the early life and
Work of Shakespeare. Of the man as he then existed, of the life
which for some twenty-eight years he had lived on this earth, of the
knowledge which he had acquired, of the pursuits in which he had
engaged, and of the literary work which he had accomplished, we
have means of knowledge fuller and more certain than we possess
with regard to many great men whose lives are separated from ours
by a much shorter interval of time ; and the man, as we know him,
and his work as we possess it, are in complete accord.

And yet Hallam wrote, with absolute truth, that of William
Shakespeare " it may be truly said that we scarcely know anything."
For he thus explained his meaning : " If there was a Shakespeare of
earth, as I suspect, there was also one of heaven ; and it is of him
that we desire to know something." Of the Shakesijeare of heaven ;
of the creator of Hamlet, Othello and Lear, our knowledge has been
fairly summed up in the words : " He lived, and he died ; and he was
a little lower than the angels." And yet one other fact is certain.
The Shakespeare of whom we would know something was one and the
same person with his eaidier self, and any knowledge which we may
gain of the one adds to our understanding and appreciation of the
other.

I have chosen the end of the year 1592 as a point in Shakespeare's
life, because it is then that we obtain our earliest view of the man, in
the light of a contemporary notice. Every student of the life of
Shakespeare is familiar with the words in which he was denounced
by Greene, who, when repenting on his deathbed of many grievous
sins, somehow forgot to include " envy, hatred, malice and all un-
charitableness." The authenticity of this passage, and its application
to Shakespeare have not been questioned, but its full significance has
I think, been overlooked.

In his ' Groatsworth of Wit ' Greene conveyed a solemn warning
to certain persons, three in number, whom he addressed as " Gentlemen,
his quondam acquaintances, that spend their wit in making Plaies."
Of these the first and third have been identified with reasonable
certainty as Marlowe and Nash. The second is probably either
Lodge or Peele. They are entreated to employ their rare wits in
more profitable courses than writing plays for play-actors. They are

1898.] on the Early Life and Work of Shakespeare. 745

warned that they were in like case with Greene, they also would be
forsaken by these " Puppets that speak from our mouths, those Antics
garnished in our colours." " Yes, trust them not," he adds, " for there
is an upstart Crow beautified with our feathers, that with his Tyger's
heart wrapped in a Player's hide supposes he is as well able to bombast
out a blank verse as the best of you, and being an absolute Johannes
factotum, is in his owne conceit the only Shake-scene in a countrie."
The line thus parodied, " O Tiger's heart wrapt in a woman's hide,"
occurs in the Third Part of Henry VI., and this circumstance, taken
with the obvious play on his name, identifies Shakespeare as the object
of Greene's invective.

Had this curious pamphlet been given to the world on the authority
of Greene, it might be disregarded as the raving of a disordered brain.
But it was revised and published in December 1592, about two months
after Greene's death, by Henry Chettle, himself a dramatist of note,
to whose pen it appears to have been attributed. For in the preface
to his ' Kind Hart's Dream,' Chettle is at pains to disown the author-
ship and to make such amends as he could to two of the playwrights
addressed by Greene. " A letter," he says, " written to divers play-
makers is offensively by one or two of them taken." There was one
of those, he tells us, " whose learning I reverence, and at the perusing
of Greene's book stroke out what there in conscience I thought he in
some displeasure writ." No such reverence for either the learning or
the art of Shakespeare led Chettle to tone down the only really offen-
sive part of the whole passage.

Of another of those who took offence he writes, that he did not
so much spare him as since he wished, for which he is as sorry
as if Greene's fault had been his own, " because myselfe have scene
his demeanour no less civill than he excellent in the qualities he
possesses. Besides, divers of worship have reported his ui^rightness
of dealing, which argues his honesty, and his facetious grace in
writing, that approves his Art."

There is no reason for applying to Shakespeare these words of
Chettle, save only a sense of their appropriateness. For it was by
one or two of the play-makers addressed by Greene that offence was
taken, and Shakespeare was not of the number. I am not, however,
careful to discuss the sufficiency of this reason, for the real signifi-
cance of Chettle's preface consists in the evidence which it affords of
the state of his mind when he edited and revised Greene's pamphlet.
When he saw no reason to tone down the only really scurrilous
passage in the ' Groatsworth of Wit " — the denunciation of Shake-
speare as an impudent plagiarist — it is impossible to avoid the
conclusion that either Shakespeare was unknown to him, or that he
saw no reason to quarrel with Greene's estimate of character and
literary ability.

Strange as Greene's words now sound in our ears, there is no
reason why they should have startled Chettle. Without accepting
the literal truth of any of the traditions, we cannot doubt that Rowe,

746 The Bight Hon. D. H. Madden [May 20,

Shakespeare's earliest biograplier, states with substantial truth that he
was " received into the company then in being at first in a very mean
rank." The playwrights of established position — Greene, Lodge,
Peele, Nash, Marlowe — had all received a University education. They
would, not unnaturally, look down on one who was not of their order,
and whose earliest dramatic work took the form, not of original com-
position, but of adaptation. The popularity with playgoers of Shake-
speare's adaptations was not likely to win the favour of the dramatists
whose works were laid under contribution. We know, on the authority
of Nash, that the Talbot scenes in ' Henry VI.' were applauded by
thousands of spectators, and we learn from Ben Jonson that even
twenty-five years later there were old fashioned playgoers who would
swear that ' Titus Andronicus ' and * Jeronimo ' were the best plays.

Thus we can easily understand, from a knowledge of Shakespeare's
early life, how it was that his first work as a dramatist — great as we
now recognise it to be in part — did not meet with immediate or cordial
reception on the part of the literary world. In the end he overcame
all opposition and asserted his supremacy, but when the volume of his
early work was completed, the time had not yet come.

It was well said by Coleridge, in one of his lectures on Shakespeare,
that a young man's first work almost always bespeaks his recent
pursuits. Not so much, I would venture to add, in the selection of a
subject, as in incidental passages and casual allusions, from which we
may discern most certainly the class of images with which his mind
is stored and which present themselves unbidden to his imagination.

If the authorship of Shakespeare's earliest play, ' Love's Labour's
Lost,' were a matter of speculation, we should conclude with absolute
certainty that it was the work of one who was thoroughly acquainted
with the studies and pursuits of school.

I am not about to discuss the vexed question of Shakespeare's
classical learning. Had I time to do so, I could not hope to add
anything to Professor Bayne's essay entitled "What Shakespeare
Learned at School," published in his ' Shakesi^eare Studies.' He
there details, from authentic sources, the general course of grammar-
school instruction in Shakespeare's time, and examines the evidence
supplied by his writings of his having passed through such a course
of study. Ovid and Mantuanus were favourite text books. So
popular was Mantuanus in the sixteenth centmy that pedants like
to him to whom we are introduced in ' Love's Labour's Lost,' under
the name of Holophernes, preferred his ' Fauste, precor, gelida,' to
' Arma virumque ' ; in other words, the ' Eclogues ' of Mantuanus
to the ' iEneid ' of Virgil. Shakespeare's love of Ovid appears
most clearly in his early writings. The story of ' Venus and Adonis '
is borrowed from the 'Metamorphoses,' and 'Lucrece' from the
' Fasti.' On the title-page of the former are two lines from Ovid's
' Elegies,' taken from a poem of which no English version had then
been published. 'Titus Andronicus' is full of allusions to Ovid.
In 'Love's Labour's Lost,' Holophernes puns on his name— Ovidius

1898.J on the Early Life and Work of Shakespeare. 747

Naso —surest token with Shakespeare of afifectionate familiarity; "Why
indeed ' Naso ' but for smelling out the odoriferous flowers of fancy,
the jerks of invention ? " The extent to which Shakespeare had steeped
himself in Ovid was noticed by his contemporaries. Meres wrote
in 1598 : " As the soule of Euphorbus was thought to live in
Pythagoras so the witty soule of Ovid lives in mellifluous and
honey-tongued Shakespeare."

The classical learning displayed by Shakespeare was precisely
what a clever boy might be expected to carry away from the free
grammar-school at Stratford. Thus Coleridge's conclusion appears
to be a just one ; " Though Shakespeare's acquirements in the dead
languages might not be such as we suppose in a learned educa-
tion, his habits had nevertheless been scholastic, and those of a
student."

This conclusion agrees exactly with the testimony of a competent
and trustworthy witness, so precisely in point that one is disposed to
ask, why it was ever thought needful to resort to speculation and to
expert evidence. If, indeed, the question of Shakespeare's classical
learning had to be decided in accordance with the opinions of learned
experts, we might well despair of arriving at a conclusion. According
to critics like Whalley and Upton, he was a kind of poetic Porson,
with head so crammed with Greek that he cannot say of valour that
it " most dignifies the haver," without the Greek word eyjtv being
present to his mind. Between this extreme, and Farmer's conclusion
that " his studies were most demonstratingly confined to nature and
his own language," you may find every possible form of intermediate
belief. I do not know a better illumination of the value of mere
opinion and expert evidence, in matters of criticism.

There is no such ambiguity about the testimony of Ben Jonson.
When he wrote of Shakespeare that he had " small Latin and less
Greek," we feel sure that Shakespeare was criticised as a classical
scholar by one who regarded himself as being, in this particular, his
superior. If I were to hear it said of one unknown to me that he
knew little law and less equity, I should conclude that the subject
of the conversation was certainly not a layman, but probably a judge,
or at all events some one who had made a special study of law.
And if I knew the speaker to be a censorious man, with a good
opinion of his own attainments, I should consider it likely that the
man of whom he spoke was a fair lawyer, though probably more
eminent in other respects.

Now the great, and, on the whole, generous, nature of Jonson, was
infected with a double dose of " the scholar's melancholy, which is
emulation." His love for Shakespeare, he tells us, and I have no
doubt truly, approached to idolatry. And yet in the very passage in
which he records his affectionate admiration, he does not hesitate to
note what he regarded as defects, and he sums up, in words which
sound strangely in our ears : " He redeemed his vices with his virtues.
There was ever more in him to be praised than to be pardoned."

748 The Bight Hon. D. H. Madden [May 20,

Jonson is not likely to have exaggerated Shakespeare's proficiency in
the classical studies upon which he justly prided himself. *' The rudi-
ments of Greek," Mr. Sidney Lee tells us, " were occasionally taught in
Elizabethan grammar-schools to very promising pupils." If Shake-
speare had some Greek, we may fairly conclude that he was a promising
pupil, and credit him with the full amount of learning which a clever
boy would carry away from the grammar-school at Stratford — scholar-
ship perhaps neither critical nor profound, and not disdaining the aid
of translations when procurable, but for literary purposes a sufficient
introduction to the masterpieces of the older civilisations.

If the early works of Shakespeare had been published anonymously,
and we had to seek for some clue as to their probable authorship,
a careful inquirer could not fail to note the frequent use of legal
phraseology, es^/ecially in the Poems and earlier plays. I have
recently seen it stated that there are no fewer than fifty-one legal
terms and allusions in the Poems, of which twenty-nine occur in
the Sonnets. I have not verified this statement, but I see no reason
to doubt its accuracy. Remarkable as is the frequency of those
allusions, the manner of their introduction is still more noteworthy.
They are for the most part of a casual character, introduced without
special reference to the matter in hand, or to the context, with which
they are often out of harmony. A poet or a dramatist may employ a
term of art with strict accuracy, without leading to the conclusion
that he was himself possessed of technical knowledge. He may have
consulted a book, or (better still) a friend skilled in the art, when-
ever it became needful to make use of technical language. But when
terms of art are used, not of set purpose, but because they present
themselves unbidden to the writer's miud, it is impossible to avoid
the conclusion that they have become, somehow or other, part of his
mental equipment. No one but a lawyer would go to a law book in
search of a simile or a pun.

It is, I think, impossible for a layman to realise the extent to
which legal terms and allusions are embedded in the ordinary lan-
guage of Shakespeare. It would be easy to accumulate instances.
Some are obvious enough, such as Eosaline's pun on the announce-
ment of three proper young men of excellent growth and presence :
" Be it known unto all men by these presents ; " and the suggestion
of Autipholus of Syracuse that a man may recover his hair by fine and
recovery, capped by Dromio's " Yes, to pay a fine for a periwig and
recover the lost hair of another man." Others are more recondite,
as when Lepidus, with a lawyer's appreciation of the difference be-
tween taking by descent and by purchase, says of Mark Antony that
his faults are "hereditary rather than purchased; what he cannot
change, than what he chooses."

There is no known fact in Shakespeare's life associating him with
the practice of the law. It is, however, reasonably certain that he
found some employment for his time and his brains between his
leaving school and his coming to London. " I would there were no

1898.] on the Early Life and Work of Shakespeare. 749

age between sixteen and three-and-twenty," says the Shepherd in
' The Winter's Tale,' " or that youth would sleep out the rest."
Shakespeare may have relieved the tedium of those years by some of
the exploits suggested by the Shepherd, but of his serious occupations
we know nothing. There is therefore nothing to exclude any con-
clusion which may fairly be suggested by his writings. The clever
and needy boy of sixteen may have found employment for a time in
the office of one of the six attorneys practising in the Court of Eecord
which we know to have then existed at Stratford. He may also
have earned his bread for a time, as tradition asserts, by teaching in
the school of Holophernes. Finally, tiring alike of school and law,
he drifted into play-acting and play-writing. Certainly the age
between sixteen and three-and-twenty does not seem to have suggested
to his mind in after life the idea of sustained eifort or fixed purpose,
but only a certainty that the " boiled brains of nineteen and two-and-
twenty " would hunt in any weather.

Such familiarity with legal phraseology as we find in Shakespeare's
works bespeaks some acquaintance with law, but not more than
could be readily acquired by a clever youth (and I suppose that
Lord Frederick Verisopht's estimate of Shakespeare still holds
good) who had served some sort of apprenticeship to the law, and
had gained access to a few law books. A man may talk of warrants,
charters, leets and law days, and not be a Lord Chancellor. He
may play on the words " recovery," and " assurance," and yet not be
a learned conveyancer. Jarndyce v. Jarndyce need not have been
attributed to a Lord Chancellor, nor Bardell v. Pickwick to a
Chief Justice, even if we did not know that the wiiter had picked up
his legal knowledge in a proctor's office. Where a writer has a
little law and sound brains he may be fairly expected to use his legal
terms aright. This is what Shakespeare for the most part does.
Mr. Castle indeed adduces several instances of the use of technical
terms, otherwise than they would be used by a lawyer, from which he
concludes that the plays were written by a layman, who sometimes
relied on his own resources, and at other times had recourse to the
aid of a trained lawyer. But why should this layman for ever hanker
after legal phrases and allusions, in season and out of season ? And
why, if he realised the need of advice, did he adventure on their use
in the absence of his adviser ? It is surely more reasonable to have
regard to Shakespeare's legal phraseology as a whole, and to draw
our conclusion accordingly. There is a curious passage in Nash's
' Epistle to the Gentlemen Students of two Universities,' in which
he writes of some that leave " the trade of noverint " and busy them-
selves with the endeavours of art, '* affording whole Hamlets, I
should say handfuls of tragical speeches." This passage, which was
printed in 1589, may not refer to Shakespeare, but that it proves that
a limb of the law turned playwright — for this is the significance of
Nash's reference to the trade of noverint — is not an improbable sup-
position.

750 The Bight Hon. D. H. Madden [May 20,

There is yet anotlier cliaracteristic of the early plays and poems,
which would be of still greater value if we were driven to discover
their authorship from internal evidence ; for it would exclude many
competitors and considerably narrow the area of search. I have
elsewhere collected the allusions to field sports and to horsemanship
which are scattered throughout the works of Shakespeare. They are
to be found in his later, as well as in his early works, but nowhere
in such freshness and abundance as in the first heir of his invention
— ' Venus and Adonis.' Of the descrij^tion of the hare-hunt in this
poem Mr. Bagehot remarks, that it is idle to say that we know
nothing of its author, for we know that he has been after a hare.
This is a concise statement of the inference to be drawn from the
Shakespearian allusions to sj)ort and to horses. In mere point of
number they are without parallel in literature. There are to be
found in Shakespeare about four hundred words and pbrases dis-
tinctly relating to field sports, horses and horsemanship. Many of
these terms of art can only be detected by those who have made a
special study of the sporting literature of the age. For example,
although the words " career " and " race " are still in use, they have
long since lost the technical meaning which they once possessed in
the language of the manege. Reading the passages in which these
words occur, in the light of the technical knowledge which Shakespeare
possessed, they acquire a fresh significance and convey a fuller mean-
ing. Time will not permit me to enter into this subject at any length,
but I may mention some of the characteristics of the Shakespearian
allusions to sport or horsemanship. Sometimes they convey a secret
of woodcraft or horse knowledge, as when we are warned against a
horse with a cloud in his face, or taught how to avoid scaring a herd
of deer by the noise of a cross-bow. Often they are used in illustra-
tion of human nature and character, as when we are told that " hollow
men, like horses hot at hand, make gallant show and promise of their
mettle," but when the time of trial comes on and they should " endure
the bloody spur," they, "like deceitful jades, sink in the trial."
Sometimes they convey a lively image, often an irrelevance, by which
I mean an idea somewhat out of place with its surroundings ; and
puns on words connected with the chase, especially on the words
" hart " and " deer," are almost beyond counting.

There is a distinctive note about Shakespeare's allusions to sport,
which I have failed to find in either the detailed descriptions or
casual allusions of any other writer. Applying Mr. Bagehot's canon,
we surely know something of the man whose thoughts for ever run
on horse, hound, hawk and deer. We know that many years of
his early life must have been spent in the pursuit of sport, and if
we were to draw any conclusion from local allusions, we should
infer that those years had been spent not far from Gloucestershire
or from Cotswold. And here we find the ShakesjDeare of fact and
of tradition in perfect accord with the testimony of his early works.

I have directed your attention to some aspects of the Shakespeare

1898.] on the Early Life and Work of Shakespeare. 751

of 1592, in regard to which he appears to be intelligible and devoid
of all mystery, save only as to the immensity of his genius. They
appertain to the Shakespeare of this earth — schoolboy ; possible
attorney's clerk ; certain huntsman, courser, falconer and horseman ;
needy adventurer ; and theatrical factotum. But what of the Shake-
speare of heaven ?

The unity of Shakespeare has not yet been questioned. No one
has doubted the personal identity of Greene's Johannes factotum
with the supreme artist, many years afterwards addressed by one of
the greatest of his contemporaries as " the wonder of the stage."
This, wrote Hallam, is " an improvement in critical acuteness doubt-
less reserved for a distant posterity."

Had Hallam written some twenty years later, his forecast might
have been difierent. A generation in which the existence of Shake-
speare has been denied, might fairly be expected to question his
unity. By " Shakespeare," I mean the author of the plays and poems ;
and his existence as a separate entity is surely denied by those who
regard him as merely a phase or casual development of another man,
and the authorship of the greatest of all literary productions as an
unconsidered incident in a life-work of an entirely different kind.

When an irrational idea is entertained by men who are in other
respects rational, we can generally find, if we search carefully, some
reason for its existence ; not, perhaps, an exquisite reason, but a
reason good enough, in the absence of a better. Eational men who
believed in the Tichborne claimant would tell you that the mother
of Tichborne believed in him, and that she ought to know her own
son : a reason good in itself, but overborne by the weight of adverse
testimony. When Mr. John Bright said that " any man who believes
that William Shakespeare of Stratford wrote ' Hamlet ' or ' Lear ' is a
fool," he gave a reason for the faith, or want of faith which was in
him, and voluminous writers have done little more than expand and
illustrate this concise statement. But he overlooked the fact that
* Hamlet' and 'Lear' were not written by William Shakespeare of
Stratford. They were the work of one who was linked to the
man of Stratford no doubt by the tie of personal identity, but sepa-
rated from him in a much more real sense by some twenty years of
thought, work, study, observation of men and manners, and (for
aught we know) of sin, suffering and remorse, in this city. Why,
between the man of Stratford and the Shakespeare of 1592 there lay
six years of work in London : a time more than sufficient to convert
an unfledged schoolboy into a learned professor.

What are the characteristics of the author of ' Hamlet ' and ' Lear '
which have been noted as irreconcilable with what we know of the
man of Stratford ? They are these : the encyclopaBdic range of his
knowledge, so vast that specialists in several branches of learning
have claimed him as their own ; his intimate acquaintance with
human nature, as it manifests itself in all times and under all cir-
cumstances, at home and abroad, in courts and palaces, as well as

752 " The Biglt Hon. B. H. Madden [May 20,

in humbler abodes ; bis familiarity with ancient literature ; bis
knowledge of foreign languages, sbown by bis use of French and
Italian books of whicb no translations are known to bave existed ;
and tbe fact tbat, in Coleridge's words, " be w^as not only a great
poet, but a great pbilosopber."

Tbe Shakespeare of 1592, as we discern him, was on bis way to
tbe attainment of these great qualities, but he had not as yet attained.
He bad lived for six years in London under tbe intellectual influence
of Marlowe, and probably on terms of intimacy with him. Marlowe
was killed in 1593, and a few years afterwards Sbakespeare, quoting
a line from ' Hero and Leander,' addressed the author as " Dead
Shepherd," in terms suggestive of personal attachment. In 1593 he
published ' Venus and Adonis,' dedicating this " first heir of his in-
vention " to the Earl of Southampton. Tbat this dedication was as
prudential and successful as his other speculations we may infer from
tbe very different language which be used a few years later in his
dedication of ' Lucrece.' He had then become on terms of iatimacy with
Southampton, which he described as ' love,' a word at that time de-
scriptive of warm friendship. If tradition speaks truly this sentiment
was returned in tbe substantial form of a gift of one thousand pounds.
The Karl of Pembroke and the Earl of Montgomery are stated by
tbe editors of tbe folio of 1623 to have prosecuted tbe plays and
" their author living " with much favour, a statement of which an
interesting illustration may be found in a note to Mr. Wyndbam's
recent edition of the Poems. The flights of tbe Swan of Avon,
according to Ben Jonson, " did so take Eliza and our James,"
that we may fairly conclude tbat be was not neglected by their
courtiers. Fuller, who was born in 1608, probably derived bis know-
ledge of tbe wit combats at the Mermaid Tavern at first hand, from
those who had witnessed or taken part in them. It was by the
publication of the Poems that Shakespeare was first introduced to the
polite society of the capital. Meanwhile bis fame as a dramatist
grew apace, for in 1598 Meres ranked him first in both tragedy and
comedy.

Of bis life in London, of tbe men and women with whom be con-
versed, of the books which be studied, of the scenes which he wit-
nessed, we may conjecture much, but we know little or nothing. If
there was something (as many have conjectured with Hallam) which
changed tbe sweet and sunny nature of Sbakespeare to gloom, tbat
something must always remain buried in mystery. It can derive no
clear or certain illustration from sonnets written (so far as can be
learned from external evidence) before the advent of this gloom
became traceable in bis other writings. His love of rural sports, and
a desire, like that of Scott, to attain a position of consequence in the
country, may explain his abandonment of London life ; but it can
never solve tbe riddle of bis total neglect of tbe greatest of all lite-
rary productions. One fact, however, is certain. The Shakespeare of
1592 was, in the course of a quarter of a century of London life,

1898.] on the Early Life and Wo7'1c of Shalcespeare. 753

subjected to precisely the kind of influences by which one endowed
with illimitable genius and boundless powers of acquiring knowledge
(and these must be assumed on any hypothesis) might in time be
wrought into the author of ' Hamlet ' and of ' Lear/ Reading his
plays in chronological order, we can trace the development of his
mighty intellect, until at last we are brought face to face with " a
thing most strange and certain " : the personal identity of the
final outcome of all those years with the man whom we have been
considering, and whom we can easily recognise as William Shake-
speare, late of Stratford. I live in daily expectation of this identity
being questioned. It is satisfactory to feel that when Hallam's
anticipation is fulfilled, the interest of the subject which we have
been considering will not be lessened. But you may then have to
listen to many lectures, each dealing with the life and work of one
only of the several individuals into whom criticism shall have re-
solved the components parts of that mighty whole, which, in the
meantime, and provisionally, we still call William Shakespeare.

[D. e. M.]

754 Lieut-General The Eon. Sir Andrew Clarhe [May 27,

WEEKLY EVENING MEETING,

Friday, May 27, 1898.

Sir William Crookes, F.K.S. Vice-President, in the Chair.

Lieut.-General The Hon. Sir Andrew Clarke, R.E. G.C.M.G.

Sir Stamford Baffles and the Malay States.

The subject which I wish to bring before the Members of the Royal
Institution to-night is one that passing events now invest with a
special and direct interest. Sir Stamford Raffles and his work at
Singapore and in the Straits Settlements must always claim the
attention of those who have dwelt in that region, and have had trans-
actions connected with it; but it has been invested with general
national importance and a peculiarly direct significance by its
relationship to the progress of events in the Far East. At the
present moment we are able and willing to appreciate the good work
Raffles did for his country in founding Singapore. We can now all
see how fortunate it was for England that, in 1819, he realised the
importance of making secure the road to the Far East, and that his
measures with that object in view were, after many difficulties,
eventually crowned with success. If he had been beaten in his
single-handed campaign against the authorities at Penang and in
India, against also the Secret Committee, and even the Cabinet at
home, our expansion eastwards would have been fettered, our trade
would have been deprived of fresh avenues, and nothing short of a
costly and hazardous war would have placed us in that position
of vantage at the southern promontory of Asia, on the open high-
way to the marts of Siam, China and Japan, which he secured for
us without a blow, and by his own unaided but indomitable energy.
We can all of us see these results to-day; but, in paying our
tribute to this remarkable man, we should recollect that he achieved
these successes under great difficulties, that he was the object of
slanderous misrepresentations, that he was opposed with a bitterness
unknown in the present phase of society, and that charges of grave
and ineffaceable purport were brought against him by his unscrupulous
and deadly adversaries. It is only within the last few months that
all the clouds obscuring the fame of Sir Stamford Raffies have been
dispelled by the unanswerable official contemporary evidence which
Mr. Demetrius Boulger has brought to light in his recent biography
of the Founder of Singapore.

If the subject of this picturesque and varied career, this spectacle

1898.] on Sir Stamford Baffles and the Malay States. 755

of a strong man, struggling, under a weight of difficulties not of his
own making, and of wrongs that he had never merited, to the goal of
triumphant achievement, appeals to you who may have never seen the
roadstead of Singapore, with the great ocean steamers passing east-
wards and westwards at pistol-shot from our batteries, you will
understand how much greater is the hold this theme has estab-
lished on the mind of one who had the honour to hold practically
the same post as that which Eafifies filled, and who was privileged
to carry out in the Malay States the wise and permanent prin-
ciples of his liberal and large-minded policy. It is that association
of place, principle and policy that has induced me to accede to the
request to address you on the subject of Stamford Raffles and his
work.

Before I draw your attention to the public side of Sir Stamford
Raffles' career I will sketch for you, as briefly as may be, that part of
his private life which preceded his attainment of official prominence
in the capacity of Lieutenant-Governor of the temporarily subjected
island of Java. Born in the year 1781, with every reason to believe
that his family was of gentle origin although its fortunes had for
some generations been obscure, young Stamford Raffles was compelled
by the necessities of his parents to accept temporary employment in
the Secretary's office of the India House. Here he did so well that
be gained the approbation of his chief, Mr. William Ramsay, long
Secretary to the East India Company, who at the earliest opportunity
brought him on to the establishment. During these years young
Raffles, after the long hours of his office, did everything in his power
to supply the defects of an imperfect education, burning the midnight
oil, or to be more exact the midnight candle, in pursuit of knowledge,
despite his mother's protest against his extravagance. He had his
reward, for early in the year 1805, before he reached his twenty- fourth
birthday, he was appointed Assistant- Secretary at Penang with
a large salary. He owed this sudden rise to the good opinion
Mr. Ramsay had formed of him, and to the general belief in the office
as to his exceptional ability, of which opinion the Chairman, Sir Hugh
Inglis, made himself the spokesman. It has now been clearly shown
that Mr. Ramsay had no other motive in securing this appointment
for his young friend than the desire to advance a deserving man, and
that when he said the departure of his assistant was " like losing a
limb " he intended no exaggeration and spoke from his heart. When
Raffles got this appointment he naturally bethought himself of getting
married and of securing a partner during his exile. Many years must
elapse before he could again set foot in England, and it was only
natural, as he said, to secure one " bosom friend, one companion to
soothe the adverse blasts of misfortune and gladden the sunshine of
prosperity." He found this lady in Olivia Fancourt, the widow of an
Assistant-Surgeon in the Madras Establishment. Her maiden name
was Devenish ; she had resided in India when her first husband had
died, and during the nine years of her second married life in the East

756 Lieut-General The Hon. Sir Andrew Clarke [May 27,

she was the paragon of all a wife should be. She gained the esteem
and respect of the Earl of Minto, who wrote of her as " the great
lady," and of Dr. Leyden, who addressed one of the happiest efiforts
of his muse to Olivia. She fascinated her husband's staff, and even
the Malay clerk Abdulla probably revealed the truth when he said
" it was she that taught him."

On arrival at Penang, or really before arrival, while at sea,
Eaffles showed that his pertinacity and assiduity were not abated by
the rise in his fortunes, by turning his attention to the study of the
Malay language. He worked hard at it, employed on his own account
a staff of native teachers and translators, and was soon a qualified
interpreter. But he became much more than a mere interpreter.
He mastered Malay history, laws, and the great principles of naviga-
tion by which the commerce of the Archipelago had been controlled.
He grasped the importance of Malacca, and by a timely remonstrance
he saved it from the fate which the Government had decreed. He
read much of Singapura, " the lion city " and metropolis of the old
Malay empire, and he probably thought of reviving its departed glory
before he knew that it would make an unrivalled maritime station.
Malay studies strengthened by a common pursuit his friendship with
Leyden, and the importance of this fact was that Leyden was then
resident at Calcutta, and that he had gained the confidence of the
Governor-General, Lord Minto. If Raffles had been an ordinary man,
the appointment to Penang would never have possessed any greater
significance than a good, well-paid post, and his name would never
have been handed down to posterity as one of our greatest Pro-Consuls.
At Penang there never was the least chance of any special distinction.
There is no need to disguise the fact that Raffles was ambitious. He
broke through the barriers of local insignificance that would have held
him confined in a vegetating existence until he added his own to the
numerous graves of his colleagues on the islaud, or returned to pass
his closing years in England with an impaired constitution and not
one of all his dreams achieved. He looked beyond Penang, he saw
the opportunity of freeing the Straits and the Spice Islands from the
jealous control of the Dutch which arose out of the temporary asser-
tion of French authority through Napoleon's incorporation of Hol-
land. These events were of public notoriety ; they formed the topic
of conversation both at home and abroad, but Eaffles alone, with a
singular prescience and forethought, at once saw how they could be
turned to Imperial advantage.

He left Penang on leave, and he went to Calcutta. He was
received by Lord Minto, on whom he made a most favourable impres-
sion, and in a few weeks he won the Governor-General round to his
policy of conquering Java as the sure way to secure for ever the
predominance of British commerce in the waters of the Far East. At
that moment Raffles was exactly twenty-nine years of age. Yet for
some inscrutable reason this half-forgotten and unappreciated public
servant is even to-day slighted, judging by the inadequate reception

1898.J on Sir Stamford Baffles and tlie Malay States. 757

his biography has met with, and by the reluctance the critics have
shown to accept his claims to greatness at the just rate his services to
the country and the Empire both demand and justify.

Well, he was only twenty -nine when, coming as a stranger, he
won the responsible ruler of India round to his views on a question
of external policy which entailed the despatch of the largest expedi-
tion up to then sent from the shores of India. He not only framed
the policy, but he was entrusted with the task of carrying it out. I
will not detain you with the details, but he discharged his task with
unerring wisdom and unsurpassed energy. He Foon discovered the
best route for the expedition to Batavia, one that had never previously
been used by Europeans. The officers of the Royal Navy laughed at
him, or rather, thought slightingly of his professed knowledge of this
sea route, and predicted nothing but misfortune, but he had the
laugh of them, for the route followed proved perfectly safe, and the
expedition reached the roadstead of Batavia without losing a ship or
even a spar. The ultimate success of the undertaking was, to a great
extent, dependent on the early arrival of the ships on the coast of
Java, and this was due mainly to the courage and confidence shown by
Raffles.

If the service Raffles rendered throughout the ^^reparations of the
Java expedition was great, so w^as his reward. He deserved it, no doubt,
but public servants do not always get what they deserve. To do that,
every one of the higher powers would have to be a Lord Minto — just,
generous, with the will to bestow the merited reward and the courage
to stand or fall by those they nominate. Well, Raffles was made
Lieutenant-Governor, with the fullest powers, of the island of Java
immediately after its conquest. I do not intend to dwell on his
remarkable administration of that beautiful and still but partially-
developed island. It will suffice to say tbat in five years he pacified
the portion left under the native sultans in a manner that no former
Government had ever attempted, he raised the industrial and agri-
cultural prosperity of the island to the highest point, and he increased
the revenue sevenfold. His government of Java forms one of the
brightest pages in the history of Anglo-Indian administration, but the
Fates, or to be more precise, the Congress of Vienna, decreed that the
island should be restored to the Dutch, and thus, except as a model,
the work of Raffles, in probably the richest and most beautiful island
of the world, came to an end.

This meant much more for Raffles than the loss of a Lieutenant-
Governorship. It signified the destruction of his hopes, of his
ambition, not for himself but for the country. Java was, in his
hands, to be the stepping-stone, the half-way house to China and to
Japan. It was to secure for England the position in those seas of an
undisputed supremacy. She was to be the beneficent mistress of the
countless islands of the Archipelago, and the security of her position
was to be based on the generosity of her commercial policy towards
the rest of the world. Raffles was a Free Trader before the phrase
Vol. XV. (No. 92.) 3 p

758 Lieut. -General The Hon. Sir Andrew Clarhe [May 27,

was known in party politics at honip. While tlie East India
Company clung to its monopolies, Eaffles, its servant, made every
port within its jurisdiction a Free port, and, with the one exception
of opium, allowed every article to be exported or imported under
all friendly flags at a customs rate of five per cent. Lastly, within
the shortest radius, he sought for the finest naval station that
Nature had provided in those seas. He thought he had found it
in Bauca, or in Billiton. All these hopes, these ambitions if you
will, were dashed to the ground by the Congress of Vienna. Of
the great fabric of beneficent rule and Imperial power created in
the mind of Raffles, and of which his energy and address had
laid the corner stone, nothing remained.

Under the shadow of this great disappointment Raffles came to
England in 1816. He returned two years later to the East as
Lieutenant-Governor of Fort Marlborough, or Bencoolen, in Sumatra.
He was charged with no special mission, nor was he entrusted with
the execution of any external policy. He was to confine his attention
to the local matters of what was called in those days the West Coast,
and he was, if possible, to reduce the heavy expenditure of the
establishment. At Bencoolen those who dreaded the active imagina-
tion and untiring energy of Stamford Kaffles felt sure that he would
have no opportunity of disturbing their tranquility by raising
burning questions, by contending for rights that they were well
content to see lost or left in abeyance. All they hoped from him
was that he v^^ould increase the cultivation of pepper, improve the
book-keeping of the ofiices, and perhaps indulge in tlie harmless
direction of natural history, that activity of mind which they knew
him to possess. Such were the motives of those in power when they
sent back to the East the man who had inspired the Governor-
General's policy in a great issue, and administered the affairs of a
thickly populated island with a skill not inferior to that of Warren
Hastings.

I have now brought you to the turning point in this great man's
career. His banishment to Sumatra, for that is what the appoint-
ment would have signified to an ordinary Governor, was intended to
put an end to his opportunities of agitating the minds of his superiors
in India and London. They did not want to be troubled any more
about the questions of the Archipelago or the Dutch proceedings
therein, and they believed that the deplorable condition of their
moribund settlements on the West Coast would effectuaUy prevent
his meddling with anything outside them.

We know how baseless was this expectation. Local affairs, the
limited horizon of a Sumatran station, were iu capable of chaining
the imagination of a man who had known how to emancipate himself
from Penang and to become one of the leading personages in the
Anglo-Indian world. He had much to do at Bencoolen. He did it.
He restored the prosperity of that station, he established an
equilibrium in the finances, and he arrested the decline in the

1898.] on Sir Stamford Raffles and the Malay States. 759

fortunes of the West Coast. But while he did this his energy, his
vigilance and his audacity remained undiminished for his great and
final struggle with England's great rival in the East. He saw that
there was no one else who would essay the task, and, with his
buoyant spirit, he assumed the direction of the necessary national
policy in this quarter of the Far East. Well for England was it
that he did so, as the opportunity he saw, if it had been then lost,
might never have recurred.

The restoration of Java to the Dutch was inevitable ; great as
was the loss and the pity, we could not retain it except by setting a
bad example to the other European Powers who wished to benefit by
the prostration of France after Waterloo. But with the restoration
of Java we had done all that the most exacting sense of justice could
require of us. There was no reason for us then to sit down supinely
while the Dutch extended the area of their authority and made their
position the base of aggressive operations at our expense. They
recovered, by. the Castlereagh Convention, Malacca and Java. They
found the island of Java in a flourishing condition. On the records of
the Government stood the facts as to the schemes and views of Eaffles.
They took over his surplus, and, to the best of their capacity, they
also took over his projects. They seized Billiton, they laid hands
on Banca, they asserted their jurisdiction at Palimbany, and they
planted their flag at Rhio. In this manner they secured much
more than they ever possessed before. Their hold on the Straits of
Malacca was tightening, and if the British authorities had remained
inactive for but a few months longer, there seems no reason to doubt
that they would have brought under their flag the whole of the
territories of Johore, within which stood the peerless harbour and
roadstead of Singapore.

At that supremely critical moment Eaffles reached Bencoolen.
He took in the whole situation at a glance. The Dutch, he said, had
scarcely left us a foot to stand on, but there was still time to secure
that foot. He reached Bencoolen in March 1818 ; he at once addressed
the Governor-General, the Marquis of Hastings, who had, in the matter
of the Gillespie charges, shown himself none too well disposed towards
Raffles, and in July he was invited to come to Calcutta to discuss the
situation. RafiQes did not waste a day. Immediately on receipt of
this invitation he hastened to Calcutta in a miserable country boat,
and laid his plans and projDOsals before Lord Hastings. He suc-
ceeded first of all in making his peace, as he termed it, with the
Governor-General, who went so far as to say, " Sir Stamford, you can
depend on me." But his second success was the greater, for he
obtained the Governor-General's authoritv to counteract Dutch
encroachments by establishing British influence and authority in
Acheen and at Rhio. In notifying this news to a frieud he added,
"At Rhio, I fear, we may be too late." Within little more than six
months of his return to the East, Raffles had thus obtained permission
to do what no one else would do, viz;, to keep the Straits open for

3 D 2

760 Lieut. -General TJie Hon. Sir Andrew Clarke [May 27,

British trade and to place a check on the excluding policy of the
Dutch. He thus resumed, in a different form, the task he had
crowned with success in Java, of obtaining on the road to the Far
East a free port and a naval station adequate for the expansion and
security of British trade. In the first act he had been beaten by the
force of circumstances, and by the fact that the political requirements
of Europe never allowed the local arguments in favour of retention
to be impartially considered ; but now, in the second act of his duel
with the Dutch, there was a reasonable chance of success, because
the Governor- General, at least, had become alive to the necessity of
doing something. Thus, for the second time in his career, Baffles
brought a Governor-General of India round to his views, and made
the policy of the country conform to his views of the situation.

On 28th November and 5th December, 1818, Raffles received his
instructions to proceed to the Straits of Malacca. In the former it
was laid down that " the proceedings of the Dutch authorities in the
Eastern Seas leave no room to doubt that it is their policy to extend
their supremacy over the whole Archipelago." To counteract the
injury to British trade from this policy it was proposed to arrange
" the establishment of a station beyond Malacca such as might command
both the Straits of Malacca and of Singapore."

The port of Rhio was suggested as the most likely place, and as
one where the Dutch had no rights. In the second despatch, pro-
vision was made for the Dutch having forestalled the British in the
occupation of Rhio. In that event an arrangement was sanctioned
with the Sultan of Johore. The significance of this reference lay in
the fact that the port of Johore was the old Zion City of the Malays,
Singapura or Siugaj^ore, and how thoroughly Raffles's mind was fixed
on this point may be inferred from his saying in a letter written, a
few days after he received his instruction, on board ship at the mouth
of the Hooghley, " do not be surprised if my next letter to you is
dated from the site of the ancient city of Singapura."

We have now reached the point at which Raffles has not only
obtained the highest sanction for his measures to counteract the
spread of Dutch influence to the exclusion of British, and the very
moment when he had practically fixed in his mind the place, Singa-
pore, by the acquisition of which he intended to defeat their policy.
I do not intend to enter into the question of the rival pretensions of
Colonel Farquhar. Mr. Boulger's researches and the official docu-
ments have settled that dispute. But having just quoted Raffles'
letter from the Sandheads, let me follow it up by saying that at once
on his arrival at Penang, on 1st January, 1819, Raffles wrote to the
Governor-General, " the island of Singapore appears to me to possess
peculiar and great advantages " for the desired station. In his own
mind, as recorded on the official records, Raffles had fixed on the
position of Singapore long before he saw it. His Malay studies had
made him acquainted with its past history, and he entertained a
reasonable hope that it would be possible to revive its ancient

1898.] on Sir Stamford Baffles and the Malay States. 761

importance under the British flag. On 29th February,* 1819, he
hoisted the Union Jack at Singapore, and in the nearly eighty years
that have since elapsed, the evidence as to the value and importance
of what Sir Stamford Raffles acquired for us has been steadily
increasing, and with every prospect of further development. We can
see with our own eyes by its geographical position the magnitude of
its trade, the prosperity of its settlers, of what momentous import-
ance Singapore is to the British Empire. Survey the ring of
British stations that girdle the globe, and I doubt if there is one
more indispensable for our security. But Baffles saw these things
in anticipation. Singapore was a barren spot with few inhabitants
and one small block-house erected in haste, when he wrote, "it
has been my good fortune to establish this station in a position
combining every possible advantage, geographical and local," and
again, " you will be happy to hear that the station of Singapore con-
tains every advantage — geographical and local — that we can desire,
an excellent harbour which I was the first to discover, capital facilities
for defence to shipping if necessary, and the port in the direct track
of the China trade; we have a flag at St. John's, and every ship
passing through the Straits must go within half-a-mile of it." These
expressions of opinion, written within a few days of the hoisting of
the British flag at Singapore, will show what its founder thought of
its future. It will suffice for me to say that all, and more than all, he
foretold has been fully realised.

That is how we obtained Singapore. Let me tell you in a few
words how nearly we lost it. You have seen how quickly Raffles
acted. Within seven weeks of his sailing from the Ganges he had
planted the Union Jack at Singapore. Those were the days of slow
sailing ships. Three weeks were taken in the voyage to Penang,
another three weeks were passed at Penang, and less than a week
sufficed for this energetic man to visit and reject the Carimonos and
to occupy Singapore by treaty with the Sultan of Johore. It was
well that Raffles acted with this promptitude, for on the receipt of a
despatch from Lord. Hastings to the effect that he intended to employ
Raffles on a special mission to the Straits, the Secret Committee sent
out a furious despatch forbidding his employment, and declaring that
"any difference with the Dutch will be created by Sir Stamford
Raffles' intemperance of conduct and language." These official
attacks so far influenced Lord Hastings that on 20th February, 1819,
he sent orders to Raffles to give up the plan of founding a port and
to return to Bencoolen. Fortunately before that despatch was even
penned the matter had been settled, and Lord Hastings supported
the fait accompli. The Dutch protested and indulged in a paper
war, which, as Raffles throughout predicted, was all they could do.
The arguments and facts were against them ; but, if there had been
telegraphs or even steamers in those days, Raffles would never

♦ The anniversary is now kept on the 6th February.

762 Lieut.-General The Hon. Sir Andrew Clarice [May 27,

have succeeded in securing Singapore in the teeth of his official
superiors.

As stated above, on the 29th February, 1819, Raffles formally
occupied on his own responsibility the island of Singapore, and con-
tinued to watch over its progress till he finally left it on the 9th June,
1823,* having on his departure received, amongst other tributes of
resj^ect and esteem accorded to him, including one from the Supreme
Council of India, an address from the people of Singapore, iu which
it states, " at such a moment we cannot be suspected of panegyric
when we advert to the distinguished advantages which the commer-
cial interests of our nation at large have derived from your personal
exertions. To yonr unwearied zeal, your vigilance, and your com-
prehensive views, we owe at once the foundation and maintenance
of a settlement unparalled for the liberality of the princii^les on which
it has been established — principles the operation of which has con-
verted, in a period short beyond all example, a haunt of pirates into
the abode of enterj^rise, security and opulence."

After Raffles' departure, Singapore and the settlements on the
Straits were, under successive Governments, limited to the ordinary
administration of an Indian out-station. The failure of a military
expedition in 1831, and the partial success of one sent in 1832 to
retrieve that failure, on the Malacca frontier, induced the Indian
Government to withhold, more or less, all intervention in the native
states amongst wliich its settlements were situated. On the transfer
of these settlements to the direct authority of the Crown the same
policy was continued, and thus remained till 1874.

In order to form a just estimate of the value of what has been
done in the Malay Peninsula it would be necessary to describe its
condition in January 1874, when it was determined that the internal
struggles which were then paralysing trade in all the western states
and decimating the population, had become a serious danger to the
neighbouring British settlements. Years of guerilla warfare between
rival ]\Ialay chiefs and their adherents on the one hand, and between
various Chinese secret societies and factions on the other, had put a
stop to all legitimate work. Towns and villages had been destroyed,
mines closed, orchards wasted, and fields left uncultivated for years.
There was no safety for life and property, no money, nO trade, and
little food in the country. Lawlessness and opj)ression prevailed
everywhere, and those who found it hard to live on shore took to the
water and made the Straits of Malacca the scene of their operations,
so that hardly a day passed but some small trading vessel would be
attacked and burnt after the entire crew had been murdered. Pro-
bably at no time had the ill fame of the Malacca Straits so truly

* Sir S. Raffles died on the 4tli July, 1826, after having been elected the
first President of the Zoological Society in the previous April. This Society,
which has given pleasure to millions of young and old, was founded mainly by
his exertions.

1898.] on Sir Stamford Baffles and the Malay States. 763

justified its reputation for acts of piracy as in the closing months of
the year 1873.

For particulars of the terrible sufferings and terrible oppression
of the Malay working classes, men and women, it would be well to
consult the reports written by the Residents and forwarded to the
Colonial Office. Briefly, it may be said that, while the facts were
more than enough to justify the interference of Great Britain, far
too long delayed, it happened that at this very time influential Malay
chiefs in Perak, Selangor and Sungei Ujong sought the assistance of
the Governor of the Straits Settlements to put an end to a state of
affairs which had got beyond their control, and in Perak the claimant
to the supreme power asked that a British officer might be sent to aid
him in the administration of the government of the country.

This was the moment at which it was decided to interfere for
this purpose, and what is known by the Treaty of Pemkore was the
result. The Governor of the Straits Settlements went to Perak,
taking with him the officers considered best qualified to assist
in the difficult task of pacifying Malays and Chinese, putting
down all violence with a firm hand, healing old sores, making, or
attempting to make, reconciliation of quarrels, restoring to their
homes women who had been captured and carried into slavery, and
dividing the mining lands between opposing factions of Chinese.
All this was done, but not all at once — this and a great deal more —
and while it is interesting to tell in a few words the result to-day
of the experiment made twenty- four years ago, it is still more
interesting to note the means by which that result has been brought
about.

A few figures and one or two facts will best illustrate this result.

In 1874 a rough approximation of the then population was
assumed at 180,000. In 1891, when a fairly reliable census had
been taken, the population of the four protected states was 424,218 ;
whilst the last census raises the population to 610,093.

The total land revenue in 1875 was 866 dollars; in 1895 it had
reached 511,237.

The total revenue of 1875, the first year in which it was at all
regularly collected, was 409,394 dollars; in 1896 it amounted to
8,434,083.

Tlie value of the total imports and exports were in 1876, as far
as then could be ascertained, a million and a half dollars; m 1896
it just touched fifty millions.

In 1874, beyond an occasional native path or elephant track
through the jungle, no road existed; now a network of well graded
and macadamised roads traverses these States. In addition, railway
works have been carried on, and are being rapidly extended, and last
year's revenue from these was a little over 300,000 dollars.

Irrigation works have made good progress.

In civil administration the establishment of judicial and police
tribunals, schools, hospitals, as well as police stations aud gaols, all

76 i Lieut.-General The Hon. Sir Andrew Clarice [May 27,

the needs of civilisation, Lave been provided ; nor lias culture, in the
formation of museums and libraries, been wholly neglected.

The sanitary boards have done good work.

The cardinal feature of interest in the story is the means by
which all piracy and land fighting, whether by Chinese or Malays,
was absolutely stamped out ; by which taxation was almost abolished,
slavery suppressed, justice done, roads and railways constructed,
prisons and hospitals built and maintained, and above all, the chiefs
reconciled to the new life, and the recognition of equality of all races
and classes before the law. It has been done by the residents laying
down and insisting on the constant recognition of the principle that
the interests of the people they were set to govern should be the first
consideration of Government officers. By learning their languages,
their prejudices, their character, and by showing them that con-
sideration which alone can secure sympathy and a good understand-
ing between Government and people, their respect, and, to some
extent, their afiection has been won. The natural tendencies of our
race are not exactly inclined to these lines, and what has been done,
and the present feeling as to how the natives should be treated, is
due to the personal influence of a succession of Residents who gained
their knowledge by their own intelligence and experience ; for there
were no authorities to consult, the administrative experiment in the
Malay peninsula standing alone, and having no parallel in British
administration of alien races.

The Residents were told they were to collect and administer the
revenues of the State to which they were accredited. They were
also told their advice was to be asked and acted upon in all questions
except those of Mahomedan law and Malay custom. At the same
time they were warned that they were only " advisers," and that if
they went beyond that they would be held responsible for any trouble
which should arise from their action, in what must have been cynic-
ally described as " a delicate and difficult position ; " but the very
elasticity and wide discretion of this policy was the foundation of its
marvellous success. It would certainly not be easy to conceive a
more impossible position. Entire control of all revenue ; to be con-
sulted about everything, and the advice tendered must be followed.
That clearly implies the responsibility for the whole Government
of the country. But then the individual who held this position
was to remember that he was only an adviser, not a ruler; he had no
means to enforce his directions, and he was warned that he would be
held personally responsible for any trouble that might arise from that
impossible position. The men to whom the work was entrusted at
once took the entire control and the responsibility with it, and trusted
to their own determination and tact to keep the peace, lead the chiefs
without driving them, but drive where necessary, and secure the sym-
pathy and goodwill of the people.

Now that the position of control is recognised, there is force to
back it, and the anomaly is at an end, but out of the difficulties of

1898.] on Sir Stamford Raffles and the Malay States. 765

that ambiguous instruction has perhaps grown the administration of
symj)athy, consideration and mutual respect which obtains between
the Malay people and the British officers in the services of the native
State Governments. I do not for a moment desire to minimise the
great work accomplished in Egypt ; but I claim for the achievements
in the Malay Peninsula the praise which is due to greater success
under more difficult circumstances.

Not by wars involving the slaughter of native races, not by
drafts upon the imperial exchequer, not by the agency of chartered
companies, which necessarily seek first their own interests, has the
development of the Malay States been attained. Their present
peace and marvellous advance in prosperity have been due to a
sympathetic administration, which has dealt tenderly with native
prejudices, and sought to lead upwards a free people instead of
forcibly driving a subject race.

The example and success of Stamford Eaffles should encourage
us at the present juncture. He showed us what could be done by
courage, confidence and a clear mind. The progress of our commer-
cial and political power in the East brought us into collision with
two formidable European rivals, the French and the Dutch. The
former were vanquished by Clive on the mainland of India, the latter
were finally crushed after an incessant struggle of two centuries by
the founding of Singapore. The credit for the latter achievement is
as clearly due to Eaffles alone as the victory of Plassey was to Clive,
and I myself hold the opinion, to which I may add I gave expression
before the publication of Mr. Boulger's biography, that of these two
great Englishmen Stamford Eaffles was the greater.

Eaffles died a poor man. No thought of accumulating a vast
fortune, or of seeking money as a means to power and patronage,
appealed to his mind. His ambitions were satisfied with work done
for the future of the empire. This was the true imperialist.

I have said enough to draw your attention to the varied, arduous
and ill-appreciated career of Stamford Eaffles. I have touched on
the magnitude of his work and the difficulties under which it was
accomplished. Injured and traduced during his life, he has been
neglected by later generations. But his work will endure as long
as the British Empire. It was achieved at a moment of depression
such as the present. The game seemed lost, the Government was in-
different and short-sighted, the enemy was up and doing, the margin
of opportunity was narrowed to the smallest compass, cowardice or
hesitation controlled our action, yet one man was able to turn the
bitter draught of defeat into the ambrosia of victory. So will it be
again if our public servants keep before them the inspiring example
of Stamford Eaffles.

The life of Stamford Eaffles is full of great lessons of vital
import to all those to whom the British Empire is alike an object of
national pride and of grave responsibility. That Empire was not built
up by the genius of statesmen, but by the patient labours, the fore-

766 Lieut. -General The Hon. Sir Andrew Clarice [May 27,

sight, and the vigorous initiative of men like Baffles. The directors
of the Honourable East India Company in London, anxious only for
immediate pecuniary returns, and Lord Hastings, absorbed in the
local affairs of India, failed absolutely to perceive the eventual
necessity for a British high road to the Far East. That Malacca was
occupied and tenaciously held, and that Singapore became a British
possession, was mainly, if not wholly, due to Stamford Raffles.*

The enormous importance of the Straits Settlements to-day, as
the key to the great ocean highway which stretches up to the Gulf
of Pe-chi-li, is abundantly recognised. But for the possession of
this key, what would now be our position in the China seas ? Yet
the man who saw into the dim future and who strove, as some strive
for personal distinction or for wealth, to gain and to keep this
priceless j)ossession, received scant recognition and few honours from
the nation to whose interests he gave his life. Almost may he be
said to have died of a broken heart. It is only now, when the
splendid fabric of the Empire is beginning for the first time to be
understood, that tardy reparation is accorded to the memory of one
of its great founders.

All important as was the work which Eaffles accomplished, his
aspirations were realised only in part. The surrender of the Dutch
islands was an act which no other nation in the world would have
countenanced. Those foreign critics who aifcct to regard the growth
of the Empire as the result of a policv of unexampled rapacity, have not
taken the trouble to read history. The total extent of territory which
we have abandoned is enormous, and the Dutch colonies have been
twice handed back to Holland. The action was magnanimous, but
the progress of the world has certainly not benefited. The restora-
tion of Java, against which Raffles strove in vain, gave back the
natives to a rule in which little consideration of their interests or
their rights found place. Sumatra, which, in British hands, would
long ago have been a thriving colony populated by a contented
race, has been the scene of continuous warfare. Raffles suggested
an alliance with Siam, which, if then carried out, would have
saved this interesting country from partial dismemberment, and
from the menace which still hangs darkly over it. His idea of a
confederacy of Malay States has been partially, at least, realised
in the Malay Peninsula, where it is my greatest pride to have
inaugurated the system which has led to jjrosperity and unexampled
development of commerce.

The great guiding principle of Raffles' policy was to understand
the native character, and to govern as far as possible by the agency
of native institutions. This is a golden rule, occasionally forgotten,
but essential to dealing with Eastern races.

The period covered by the official life of Sir Stamford Raffles was

* In tliis sketch I have purposely omitted to mention other names than that
of Raffles, in order to avoid undue lengtheninc; of the narrative.

1898.] on Sir Stamford Baffles and the Malay States. 767

a turning-point in our relations witli tlie Far East. A new chax^ter
in the history of those relations has now opened. The beginning
of the century saw the establishment of that great trade route
which has since conferred upon us four-fifths of the commerce of
China. With the excejjtion of the acquisition of Hong Kong with
Kowlon in 1812, and of the rising colony of North Borneo, Great
Britain has not added to her possessions in the China Seas. Port
Hamilton, lying a short distance south of Korea, was occupied only
to be abandoned. Throughout these years our policy has been to
leave China territorially intact, and to open up her resources by
the agency of Treaty Ports. That policy is now practically at an
end. Since Raffles founded Singapore, Kussia has become firmly
established in the Far East, and her policy, long evident, of
occuj^ying Manchuria, and such ports in the Gulf of Pe-chi-li has
now been realised. Germany is established on the China sea-board,
with claims and concessions which extend into the Hinterland.
Meanwhile France has moved up from the South, and is about, it is
said, to occupy a port opposite to Hainan. The partition of China may
be said to have commenced. While we might have j)i"eferred that the
opening out of this vast country should have been gradually carried
out through its own ports, other powers, more ambitious, perhaps, and
less patient, had other views, and have decided to attempt by a direct
process what we were content to leave to indirect methods. Sooner
or later this was absolutely inevitable, unless China showed promise
of an internal awakening of which there was no real hope. I do not
see in the recent proceedings of Russia, Germany and France any
cause for alarm or any ground for recrimination. We are not and
we never were prepared to occupy Manchuria ourselves. We have
no right to complain if Russia here and Germany in Shantung under-
take to develop the resources of these territories. To Russia a warm
water port in the East is a real need. Geographical conditions all
pointed to the Liao-Tuug peninsula as furnishing such a i^ort. In
occupying Port Arthur and Talienwan, Russia is simply fulfilling
her evident dtstiny and acting in obedience to natural forces. Her
action creates no legitimate grievance. We have no right to claim
to exclude another power from territory which we do not intend to
occupy. I believe that in spite of restrictions the opening up of
Manchuria will benefit British trade just as the development of
European Russia has added to our commerce. Our only wise
course is to recognise facts long foreseen, and since the partition
of China has commenced to make certain of our share. I do not
gather that any step in this direction has been taken. We are
apparently to occupy Wei-hai-wei, which lies 600 miles beyond our
sphere, and we have done nothing to secure our position at the
mouth of the Yangtse, The ancient fable of the dog and the bone
stands true now as always. By reaching after the image of a
power which is not to be ours, we risk losing the real substance.
I consider, therefore, that we should welcome a Russian occupation

768 Sir Stamford Baffles and the Malay States. [May 27,

of Manchuria and a German occupation of Shantung; but that we
ought at once to clearly define our sphere of future direct influence
in central China, and take immediate steps to make that influence a
reality when the time comes. We deferred providing India with a
frontier line until the Russians had advanced across the plains of
Central Asia, and difficulties were the natural result. If we defer
defining our share of China greater difficulties will assuredly arise.

No one power can monopolise the trade of an opened-out China.
There is room for all, and we can, if we choose, secure our just
share. If we do not maintain our present proportion of the whole
trade of China, it does not thereby follow that we shall not gain
enormously, for that whole trade at the present time is but a fraction
of what the future will bring. If, as I believe fully, we shall keep
our full share of future commercial advantages, it will be due in
great measure to the wisdom and the foresight of Stamford Raffles,
who, in Singapore, secured for us the great gate of one of the most
important trade routes of the world.

[A. C]

1898.] Development of the Tomh of Egypt. 769

WEEKLY EVENING MEETING,

Friday, June 3, 1898.

Sir Henry Thompson, F.R.C.S. F.R.A.S. Vice-President,
in the Chair.

Professor W. M. Flinders Petrie. D.C.L.
Professor of Egy2)tology in University College, London.

Tlie Development of the Tomh in Egypt.

The general ideas about tlie Egyptians are so bound up with their
preservation of the dead, that some connected account of the develop-
ment of the tomb may be of interest to others beyond the group of
specialists ; the more so as my aim is to illustrate the sequence of
ideas and of gradual changes in series, rather than to deal with solely
archaeological matters.

The reasons that the tomb has become so much associated in our
minds with the Egyptians are partly real, partly accidental. No
doubt the Egyptian thought much of a future state, attached great
importance to it, and provided for it in every way that he could devise.
Yet we should be taking a very one-sided view if we supposed that
the dead were more thought of than the living. It is owing to the
accidental conditions that the tombs are so far more noticeable than
the houses of ancient Egypt. The tomb was always placed on the
desert high above the inundation, and often imperishably cut in the
solid rock. The house was usually in the fertile plain of the NilCy
and is therefore now buried ten, twenty, or thirty feet in the alluvial
deposits left each year by the inundation.

Ancient Egypt has all been covered up far out of sight, except
such works as stood on the raised desert edge of the valley ; and
naturally enough the greater part of these remains are for the dead
rather than for the living. Hence our ideas are liable to be very
one-sided as to the relative importance of the house and the tomb in
the real life of the Egyptians, and we judge of them almost as im-
perfectly as English life might be judged if the will office in Somerset
House were its only evidence.

It is as impossible to understand the arrangement of a tomb without
knowing the theory of the soul, on which it was constructed, as it is
to understand a temple without knowing the religion, or a house
without the social life. The Egyptian had four theories about the
soul, probably belonging to successive waves of population that had
overflowed the country from different sources. There was the bird

770

Professor W. M. Flinders Petrie

[June

.o

m

T

theory, according to which the soul or ha fluttered about in and out of
the tomb as a human-headed bird ; the spiritual body or Jca also
coming out of the tomb and wandering about. This soul and ghost
needed sustenance, and were fed by the tree goddess, who dwelt in
the thick sycamores which overshadowed the cemeteries. This
theory more probably belonged to the earliest negroid inhabitants of
Egypt.

Secondly, there was the Osiris theory, according to which the
deceased went to the elysian kingdom of Osiris, and there ploughed
and sowed and reaped and threshed the heavenly corn. This may
probably belong to the Libyan stratum. Thirdly, there was the Solar
theory, according to which the soul went to join the company of
the gods in the boat of the sun-god Ra, which sailed daily across

the waters above the firmament, or
heavenly ocean. This seems due to
Mesopotamian influence, to which the
l)egiDuings of hieroglyphs are also to
be attributed. Fourthly, there is the
mummy theory, according to which the
body must be imperishably preserved
for ages until reunited to the soul.
This was perhaps due to the Red Sea
invaders of Phoenician kinship.

Now all these theories were mixed
together throughout historical times,
and combined as best they might be,
though each is mutually destructive of
all the others if logically carried out.
The most usual theories with which we
have to deal in considering the tombs
are the first and last combined, — the
ha-hird of the soul, supposed to fly in
and out of the grave, the ha or spiritual
body to come out in search of food,
and the mummy all the time lying inert
in the sepulchre. Thus we see it on
a papyrus, where the &a-bird is flying
down the pit from the door of the
tomb, bearing food and drink to the
mummy lying below. In one of the
rock-cut tombs of Deshasheh there is a beautiful provision for such
visits. The well-shaft was flagged over with slabs in the chamber
of offerings, but a little channel in the rock gave place for the ha to
pass from the well into the upper chamber where the statues were
placed, which it desired to visit and inhabit. And another little
channel opened from the statue-chamber out to the oj^en air on the
hill top, so that the ha and Jca could thus go in and out to visit
both the tomb and the outer world. Any one who has seen the lar^^e

¥

Fig. 1. — Section of tomb, from a
papyrus, showing door above,
•well-shaft with ba flying down,
and muramy in chamber w^ith
ofterings below.

1898.]

on the Development of the Tomb in Egypt.

Ill

serious owls, with half-human expressions, which flit noiselessly up
and down the open tomb shafts, can readily understand whrxt the
Egyptian thought when he credited the fleeting soul with like action.

Having thus before us the theory of the soul and of burial, we
can now turn to consider the actual tombs.

The oldest burials that we know in Egypt are those belonging to the
prehistoric population, which diifered greatly from the historical Egyp-
tians. They belong to the age when only the bird theory and Osiris
theory were in force, and perhaps the sun-god theory ; but certainly
when the mummy theory was quite unknown. Instead of preserving
the body by mummifying, they often cut it up and buried only the
bonesj or only a part of the bones. The bodies, moreover, are always

Fig. 2. — Typical early tomb, plan and ssction.

buried in a contracted position, and not laid out like the mummy.
The graves are open square pits, lined with mats, and roofed over
with beams and brushwood. Thus they were quite different from the
later type of Egyptian tombs. It is well to see thus that the actual
remains that we find reach back to a time before the general soul-
tbeory of later ages had yet been brought in.

But it is the later time of the historical development of the tomb
that we have mainly to consider at present. The tombs that we
actually have for study range continuously from about 4000 b.c. down
to Roman times ; but the principal age of consecutive development
is from about 4000 to 2500 b.c. or the IVth to the Xllth dynasty.
After that time no new ideas were introduced in the ordinary tombs,
and only gradual decay and simplification is to be seen.

772

Professor W. M. Flinders Petrie

[June 3,

The earliest tombs of the simplest type, such as I have found in

the cemetery of Dendereh, show only the essential parts. There is
a sepulchral chamber under the ground (see Fig. 2) ; a square pit
to reach that ; a mound heaped over the pit, either of mere earth
held together by a brick wall, or else of mud-brick throughout ;
and lastly a doorway figured always on the east face of the mound,
at which the &a-bird was ^.supposed to [fly out, and the /i:a-ghost to
walk out to receive the food which was offered to it. The essential
parts of this door are (1) the lintel or j^rnie/, with a figure of the
dead and his name and titles, over the^ door ; (2) the jamhs which

WtM

^^

1

i

t

Fig. 3.— False door. Tomb of Ahat.

support this ; (3) the niche or entrance between the jambs with a
figure of the dead coming forth ; with (4) a round roll or drum,
imitated from a log lintel to the door, which generally bore only the
name, with perhaps a short title. This doorway for the soul, or
*' false door," as it is now commonly called, is a most necessary part
of the tomb ; it became developed into a great monument in itself,
and finally changed and dwindled down into the mere funeral tablet
on a small scale. This whole raised mound and false door is known
by the modern name of a mastaba, or " platform " in Arabic.

But the survivors craved to have some immediate token of the
dead, to which their offerings might be made. If the ka, or spiritual

1898.]

on the Development of the Tomb in Egypt.

773

body, passed out through this door, why not give it some abiding
place in its own likeness ? And, to do this, what more natural than
to picture it in the doorway ? Such an image would be obviously
a suitable abiding place for the wandering immaterial ka, where it
could rest and be refreshed by the provision which was brought by
its pious descendants. Accordingly, a figure in relief was sculptured
in the doorway niche ; and in front of that the food was laid, and the
drink poured out into a trough of stone, on an altar of offerings
that was placed before it.

The next step was to have a statue of the dead, so as to simulate
the living person most completely. The more indistinguishable it

Fig. 4. — Tomb of Ka-aper, plan. Lower part is detail of upper plan
five times larger. So also in the following plans.

was from life, the more happy the ka would be when inhabiting it.
Thus a grand impulse was given to the most realistic art and the
most expressive portraiture ; and it is to this requirement that we
owe the brilliant examples of Egyptian art that have come down to
us. This statue, however, could not be left in the open air before
a tomb, even in the Egyptian climate ; it was too much exposed to
injury, which would grieve and hurt the ka. So a little room was
added in front of the false door, with a niche in which the sentient
statue was preserved, as in the tomb of Ka-aper at Saqqara (Fig. 4).
Here also the statue of his wife was found, which is one of the
most life-like of these wooden figures that has been preserved to us.
Here the statue was safe, and tlic family could visit it, and lay their
Vol. XV. (No. 92.) 3 e

774

Professor W. M. Flinders Petrie

[June 3,

offerings before it. Yet the statue was exposed to possible injury.
So the desire of the family to see it was subordinated to their wish
to save it from harm, and it was walled in by screening off the end
of a corridor before the tomb ; the corridor itself being an enlarge-
ment of the statue-chamber, where the offerings were made. Such
is seen in the tomb of Ka-mena, at El Kab.

The next step for the preservation of the statue was to deepen
the recess of the false door so as to hold the statue within it. This
was done in the tomb of Nefermaat at Medum. There a very deep
niche contained the statue, safely walled in with solid masonry across

Fig. 5. — Wooden statue oi wife of Ka-aper.

the entrance. Then the jambs of the doorway were expanded
laterally to form a fa9ade, but yet each made of one single stone.
To protect and enlarge the mastaba, two successive coats of brick-
work were added all round it. In placing the first it was not desired
to hide the fagade, so a cross passage was left in order that the sculp-
tured stone fagade should remain visible, and a direct passage was
left through the brickwork. The outer coat of brick covered the
entrance finally, and a court was added in front for the offerings.
This is a particularly important link in the series, as we see how
the wish to leave exposed the sculptured facade of the niche led to
a cross passage being left inside the brick coating (Fig. 6).

1898.]

on the Development of the Tomh in Egypt.

775

Observe how in the next tomb, that of Bahotep at Medum, this
cross passage has become incorporated in the primary construction,
and a cruciform chamber of stone is the result. The statues of
Eahotep and Nefert were placed in the two recesses thus formed, one
on either side. Two coats of brickwork were superadded, so as to
entirely close the chamber ; a false door was made in the outer coat,
and a court for offerings built before it, in which lay a large quantity
of little cups and dishes of pottery. Meanwhile, a second false door
in the same mastaba — that for the wife Nefert — remained in the
undeveloped form of a simple niche, because there was no need for
it to hold her statue, which was in her husband's chamber. So far.

Fig. 6.— Plan of tomb of
Nefer-maat.

Fig. 7.— Plan of tomb of
Rahotep.

the statues were safeguarded, but the family could see no more than
a stranger could.

The next point of change was in the wish for the family to see
the sculptures, and enter the chamber when they came with offerings ;
while yet the statue was to be better secured. This is seen done in
the tomb of Seker-kha-bau (see Fig. 9). Here the end of the cross
chamber is walled off to hold the statues, thus forming a separate
closed cell for them ; and this cell is commonly known to the modern
natives as a serd-ah. The chamber itself retains the panelled con-
struction typical of the mastaba face, showing that its true nature
as a part of the primary mastaba was not forgotten, although it was

3 E 2

776

Professor W. M. Flinders Petrie

[June 3,

now enclosed in front to form a chamber within the mass. So far,
I have only dealt with tombs belonging to the first fifty years or so
of which such remains are known coming a little later. The next
step was to make a faQade front to the chamber, and to bring out the
panelled pattern, or repetition of false doors, on to the outer face.
This is shown in the tomb of Ptahshepses at Saqqara.

Next a regular enclosure wall was put on before the tomb front,
as we see in a tomb at Medum (No. 22). There the chamber is com-
plete ; but an outer passage has been added, and the serdab is walled
off at the end of it, just as it had before been walled off at the end

Fig. 8. — Head of Nefert, in limestone.

of the primitive passage which developed into the chamber. Another
pit or chamber appears in the mass, probably for casting the
funeral offerings in ; as it was a custom to ascend the mound of a
mastaba, and leave dishes and jars of offering on the top near the
mouth of the pit. The pit or well is to the right hand. When —
as here — the well has been moved away to the right, and the chamber
or false door to the left, it was because a passage had been developed
between the well and the funeral chamber ; and thus the false door
was kept always close before the actual place of the body below.

We reach the full completion of this type, rather later on, in the
Vlth dynasty tomb of Senna at Dendereh. There the passage in

1898."

on the Development of the Tomh in Egypt.

in

front is regularly formed with an entrance door, and it covers sixteen
false doors along the front of the mastaba. The chamber has been
lengthened out greatly. No serdab is to be seen, as that apparently
was a Memphite feature unknown in the upper country. And the pit
is long in order to allow of a coffin being lowered at full length with
the body inside it.

Much the same construction appears in the large mastaba of Prince
Mena of the Vlth dynasty at Dendereh. Two pits appear there ; that
nearest the front leads to the funeral chamber lying behind the offer-
ing chamber. The further pit led to another chamber containing
pottery, and was doubtless for the offerings. How this was reached
is seen at the right hand, where a door from outside leads into a court-
yard with a bench along two sides of it. From this court a flight of
steps led on to the top of the mastaba ; the blank part beyond the
steps having been covered with their continuation upward, now de-
nuded away. The squares across which the shading is carried are

Fig. 9. — Plan of tomb of Seker-kha-bau at Saqqara.

merely construction cells left hollow in the brickwork, and filled up
with gravel.

The tomb was further elaborated by the addition of courts and
chambers in front of the true mastaba. In the tomb of Nenkheftka
at Saqqara, the chamber, its false door, and its serdab, with a slit
through which the statue might receive its incense, are all within the
mastaba. Subsequently three chambers were added on the front of
the mastaba, to serve as an introduction to the rest.

This is seen further developed in the tomb of Ty at Saqqara,
where the chamber has two false doors (for Ty and his wife), a serdab
on the left of it, with three slits for censing the statues. A new
supplementary chamber appears to the right of it. The front is
enclosed so as to form a passage, in which is a false door as in other
examples noticed. The new feature is a large court prefixed to this
passage, containing twelve pillars, and approached by a porch with
two pillars (see Fig. 10).

778

Professor W. M. Flinders Petrie

[June 8,

This type was carried further by prefixing the pillared court
directly in front of the chamber, as in a tomb at Dendereh. And the
same is carried out more fully in the tomb of Ateta at Saqqara.

Lastly, the court was incorporated entire in a single construction
of the mastaba as a square block of building in the tomb of Ptahhotep
at Saqqara, in which the primary mastaba is lost sight of in the in-
creasing complication of chambers.

Such complication was, however, only exceptional. On coming
down about a thousand years later, we still find the old type of
mastaba existing, as in that of Mentuhotep at Dendereh. There the
faQade has thirteen false doors along it. The chamber has become
lengthened out with a continuation to the whole length of the mastaba,
and an entrance appears in the north end of the mastaba, the purpose
of which we cannot now be certain about.

Fig. 10.— Plan of tomb of Ty.

The most distinct change in the later time, that is to say, about
the Xlth dynasty, or 2800 b.c, was in the funeral pits. In all the
earliest tombs they are square : and soon after they were lengthened
out from north to south, and ran southward into the funeral chamber,
which lay behind the false door. In the later time, however, they
were placed just behind the false door, with the chamber west of them
below. And they were therefore lengthened from east to west, in
order to pass the coffin more conveniently into the chamber. This
distinction in the direction of the pit, at first north to south, and later
on east to west, is one of the first tests of the age of a mastaba. Often
two pits were made side by side, as here, leading each to a chamber,
apparently for the husband and wife separately. One false door
served for both of them, and this would not be unlikely, as the wife

1898.]

on' the Development of the Tomh in Egypt.

779

is often placed together with her husband on his stele in the false
door. One tomb is peculiar for having an annex on the south, with
a long chamber but no false doors. The doorway left in the wall
between the two is probably merely structural, as both mastabas were
filled up solid with gravel. Such annexes occur in other cases, and
are as yet unexplained.

A usual feature of the Xlth and Xllth dynasty mastabas — at
least at Dendereh — is to revert to the early type where the passage-
chamber opened from the end. In one case there is a mixed form
with the front entrance still made, and yet the end open.

Fig. 11.— 13l■ick^Y0^k tuuuel in tomb of Adu I.

We now pass from the consideration of the plans of these tombs,
in which we have seen every stage of development, from the primi-
tive mound with a niche in the side of it, to the elaborate mass of
chambers for various funeral purposes, and we turn back to note the
development in the sections of the great tombs of the feudal princes.

The earliest example is one at Medum, where we see the central
pit not opening directly into a chamber but into a sloping passage
which leads to the chamber. So far we have not found any early
tombs (except pyramids) which have a sloping entrance passage, and
that type does not seem to have ever been adopted for small tombs,
but only for those belonging to rulers.

780

Professor W. M. Flinders Petrie

[June 3,

In the later part of the old kingdom, about 3400 B.C., we have a
splendid series of tombs of the Princes of Dendereh, built upon the
type of the sloping passage. Adu I. built a grand vaulted tunnel
of brickwork, which led down to the funeral pit. This tunnel has
four rings of brickwork in the vault arch, and is finely built. It
would be set down as Roman by most persons, but in the last few
years we have pushed back the history of the Egyptian arch of brick
to the XlXth dynasty, then to the Xllth, and now to the YIth
dynasty. Probably it began even earlier, but it is here in full use at
3500 B.O.

In the section the entrance is through an arched doorway in the
outer wall. That opened on a very narrow court or passage, in
which a stairway led to the top of the mastaba, as in Mena's. This
court was filled up with brickwork to cover the entrance to the tunnel.

ADU 11

Fig. 12. — Sections of tombs of Adu I. and Adu II.

The tunnel ran down at a steep slope, the roof of it afterwards turn-
ing horizontal to meet the wall at the tower, and it was walled up.
The well did not cause any break in the floor, and scarcely any on
the side of the passage, which runs on downward in the rock to the
funeral chamber. Two small chambers at the sides of the passage
contained funeral ofi'erings of pottery, &c. Entering the chamber, it
is of a T form, wide on either hand, and then narrowing to a long
recess of just the wirlth of the sarcophagus lid. The sarcophagus
itself is sunk in the rock floor, and the lid lay on the floor, or possibly
with a pavement flush with the top. The whole chamber and coffin
recess was lined with sculptures of ofi'erings ; this provision for the
support of the ka having been at this age transferred down from
the place of ofi'erings above to the actual place of the body below the
ground. This tomb is the most complete of this type, and enables
us to understand the others which follow it.

1898.] on the Development of the Tomb in Egypt. 781

The next tomb, that of Prince Adu II., has the same arched door-
way. The passage is much steeper, as they wished to reach the same
depth more quickly. The well is at the end of the passage, and not
intersecting it midway. The chamber is T-shaped, as before; but it
is lined with bricks, and had brick vaults for roofing each part ; all
of these have now fallen in, together with much of the gravel rock
above.

The plan of Adu II. has the ofiering chamber and well in the
usual positions. But, in addition, there is a second well in the N.W.
corner, which was, doubtless, for his wife Ana, who appears on a
tablet with Adu ; in the chamber at the bottom was a female skull.
The chamber of the second well was to the south, so that it came
nearly behind the second false door in the upper chamber of offering.
The large false door is exactly in front of the place of the sarcophagus
in the main funereal chamber. The front of this mastaba has a full
development of the false-door decoration : twelve doors on one hand,
and eighteen on the other, thirty in all. A feature of these large
mastabas of the nobles is the provision of tombs for their families
near them, much as several of the kings had the small pyramids of
their family adjoining their own pyramid. This plan is most distinct
in this mastaba, where a court is added on at the south end, containing
nine pit tombs for the family of Adu, beside a tenth in front of the
false doors.

The next tomb shows a new departure in construction. The very
steeply sloping passage of Adu II. had probably caused trouble in
making the barrel roof of it — an early settlement of the lower part
is to be seen. So a new idea appears in the providing a horizontal
barrel roof to a sloping passage, thus keeping all the brickwork level,
while the floor rapidly descends. The result is a passage which is
about fifteen feet high at the end. The well is put nearer to the end
of the passage, and the sloping floor continues down past it into the
chamber. This lower, or funereal chamber, has so much caved in
that the details are lost.

Having thus succeeded in economising material by the construction
of dofty hollows vaulted over, the same principle was carried further
in-*;the mastaba of Prince Merra. Here an entrance passage opens
into a court, from which a flight of steps led to the top. But there
is no doorway from this court into the passages. The only entrance
was by a well behind the court, which led to a high vaulted passage
with sloping floor. This passage was lighted by a high-up archway,
at the deep end of it opening on to a well shaft. Beyond the wall
was another lofty passage chamber with a domed roof, and through
this the funereal chamber was reached. This was much simpler and
poorer than before, not having any lateral branches, but being merely
a place large enough to get in the sarcophagus and place it to one
side. Nor was there any sculpturing of the sides, or indeed any
lining.

782 Professor W. M. Flinders Petrie [June 3,

The last stage that we have found in this series is that of Prince
Beb, where the well of entrance and the second well are placed near
together, and nothing comes between the high-vaulted sloping passage
and the funereal chamber. In this last there is no inscription on the
outside of the mastaba nor on the chamber ; but the whole care was
given to crowding the inside of the coffin with very lengthy magic
texts. This seems to mark a change of belief, from the earlier idea
of the lea wandering about from the tomb, inhabiting its statue, and
accepting its offerings, to the different idea of the importance of the
mummy and the need of its having the preservative charms as close
to it as possible. Thus in this series of tombs we have seen the
earliest at Medum, with a central well and sloping entrance to the
chamber ; the long sloping passage of Adu I. prefixed to the well
entrance ; the well pushed on to near the chamber in Adu II. ; the
start of high-vaulted spaces in the next tomb ; the extension of
these large spaces in order to economise material, with barrel and
domed roofs ; and, lastly, the rearrangement of the parts. If we
could extend this chain onward beyond the century or two which it
covers, we should doubtless be able to trace many more changes into
diverse forms ; but the lack of material is our difficulty, and it is
only this spring in my work at Dendereh that the present series has
come to light.

I do not propose here to deal with the series of changes to be
seen in the construction of pyramids, as that alone would be a large
subject. But we may notice how the earliest type of pyramid starts
from the mastaba with a long sloping passage. The royal mastaba
tomb of Seneferu had such a passage, starting — as do these passages
of the princes' tombs — from the ground level. The next stage was
to add a coat of masonry around the pyramid like the successive coats
around Rahotep's mastaba, and to continue the original mass upward.
This was done seven successive times, each time supposed to be the
last, as the masonry was finely finished off with polished surfaces.
Finally came the idea of putting one continuous coat from top to
base, and so the first pyramid came into existence. When once this
form was started, the later kings designed their pyramids at one
stroke and had no such intermediate steps of construction ; this is
obvious when we look at the arrangement of the internal passages.
So we must by no means sui3pose that because the first pyramid was
thus developed, that therefore every pyramid went through the same
stages.

Of the later times of the Egyptian kingdom very little architec-
tural material has been examined from the cemeteries. In the
XXVIth Dynasty, about 600 B.C., tombs were made with a well shaft,
and one chamber or several at the bottom of it under the ground, but
we know nothing of the surface buildings. Too often any rich tomb
was provided by ejecting the former occupier of some noble structure.
The stages of the latest degradation can be traced. The deep well
and chamber became shortened and simplified in the Ptolemaic times.

1898.] on the Development of the Tomb in Egypt. 783

At the end of that period the chamber was made still smaller, and
the coffin was left projecting into the well. Then it was simply
placed in the well, which became thus a deep grave and nothing
more. In Roman times the well was made shallower stage by stage,
until at last it became a mere shallow grave, only two or three feet
deep. Finally the whole system of preserving the body and burying
a special class of funeral objects came to an end with Christianity in
Egypt, when the body was buried in the clothes worn during life,
and any objects buried with it were those which had been actually
used by the person.

[Note. — Although the lower edge of the plans is east and the top west, yet
the reader's right hand is south and left hand north, owing to the plans having
been reversed in making the blocks.]

[W. M. F. P.]

GENERAL MONTHLY MEETING,

Monday, June 6, 1898.

Sir James Ckichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Arthur Wemyss Horsbrugh, Esq,
was elected a Member of the Royal Institution.

The Special Thanks of the Members were returned for the
following Donations to the Fund for the Promotion of Experimental
Research at Low Temperatures : —

£ s.

Mrs. G. J. Romanes 5 1

Sir Frederick Bramwell, Bart 100 0

Professor Dewar 100 0

Dr. Ludwig Mond 200 0

Charles Hawksley, Esq 100 0

Sir David Salomons, Bart 21 0

Dr. Rudolph Messel 100 0

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

The French Government — Documents Inedits sur I'Histoire de France ; Lettres
de Catherine de Medicis, Tome VI. 1578-79. 4to. 1897.
Topographie Historique du Vieux Paris. Region Centrale de I'Universite. 4to.
1897.

The Lords of the Admiralty — Nautical Almanac Circular, No. 17. 8vo. 1898.

784 General Monthly Meeting. [June 6,

Accademia del Lincei, Reale, Roma — Atti, Scrie Quiota : Rendiconti. Classe di

Scienze Fisiche, etc. ; 1° Semestre, Vol. VII. Fasc. 9. 8vo. 1898.
American Geographical Society — Bulletin, Vol. XXX. No. 2. 8vo. 1898.
Astronomical Society, Royal — Monthly Notices, Vol. LVIII. No. 6. 8vo. 1898.
Bankers, Institute of — Journal, Vol. XIX. Part 5. 8vo. 1898.
Berlin, Royal Frussian Academy of Sciences — Sitzungsberichte, 1898, Nos. 1-23.

8vo.
Boston, U.S.A. Public Library — Monthly Bulletin of Books added to the Library,

Vol. III. No. 5. 8vo. 1898.
British Architects, Royal Institute o/— Journal, 1897-98, Nos. IH, 14. 8vo.
British Astronomical Association — Journal, Vol. VIII. No. 6, 8vo. 1898.
Camera Club — Journal for May, 1898. 8vo.

Chemical Industry, Society of — Journal, Vol. XVII. No. 4. 8vo. 1898.
Chemical Society — Journal for May, 1898. 8vo.

Proceedings, No. 195. 8vo. 1898.
Cornwall, Royal Institution o/— Journal, Vol. XIII. Part 2. 8vo. 1897.
Cracovie, V Academic des Sciences — Bulletin International, 1898, No. 3. 8vo.
Crosby, Lockwood & Son (the Publishers) — Catalogue of Scientific and Technical

Books. 8vo. 1898.
Dax, Soci^td'de ^ordct— Bulletin, 1897, No. 4. 8vo.
Editors — American Journal of Science for May, 1898. 8vo.

Analyst for May, 1898. 8vo.

Anthony's Photographic Bulletin for May, 1898. 8vo.

Astrophysical Journal for May, 1898. 8vo.

Athenaeum for May, 1898. 4to.

Author for May, 1898.

Bimetallist for'lMay, 1898.

Brewers' Journal for May, 1898. 8vo.

Chemical News for Mav, 1898. 4to.

Chemist and Druggist for May, 1898. 8vo.

Education for May, 1898. 8vo.

Electrical Engineer for May, 1898. fol.

Electrical Engineering for May, 1898.

Electrical Review for May, 1898. 8vo.

Engineer for May, 1898. fol.

Engineering for May, 1898. fol.

Homoeopathic Review for May, 1898.

Horological Journal for May, 1898. 8vo.

Industries and Iron for May, 1898. fol.

Invention for May, 1898. 8vo.

Journal of Physical Chemistry for May, 1898. 8vo.

Journal of State Medicine for May, 1898. 8vo.

Law Journal for May, 1898. 8vo.

Machinery Market for May, 1898. 8vo.

Nature for May, 1898. 4to.

New Church Magazine for May, 1898. 8vo.

Nuovo Cimento for March- April, 1898. 8vo.

Physical Review for April, 1898. 8vo.

Public Health Engineer for May, 1898. 8vo,

Science Abstracts, Vol. I. Parts 2-5. 8vo. 1898.

Science Siftings for May, 1898. 8vo.

Travel for May, 1898. 8vo.

Tropical Agriculturist for May, 1898. 8vo.

Zoopliilist for May, 1898. 4to.
Essex Technical Laboratories — Journal, August-December, 1897. 8vo.
Florence, Bihlioteca Nazionale Centrale — Boiletino, No. 297. 8vo. 1898.
Franklin Institute — Journal for May, 1898. 8vo.

(geographical Society, Royal — Geographical Journal for May, 1898. 8vo.
Imperial Institute — Imperial Institute Journal for May, 1898.

1898.] General Monthly Meeting. 785

Iron and Steel Institute — Journal, Name Index, Vols. I.-L. 8vo. 1898.
Ives, F. E. Esq. (the Atithor) — Kromskop Colour Photography. 8vo. 1898.
Janet, Charles, Esq. (the Author) — Natural History Papers. 1897. 8vo and fol.
Jervis, Chevalier G. (the Author) — Guida alle Acque Mineral! d'ltalia. Provincie

Meridional!. By G. Jervis. 8vo. 1896.
Johns Hopkins University— American Chemical Journal for May, 1898. 8vo.
Life-Boat Institution, Roj/al National — Annual Report for 1898. 8vo.
London Counti/ Council Tecknieal Education Board — London Technical Educa-
tion Gazette for April-May. 1898. 8vo.
Manchester Geological Society — Transactions, Vol. XXV. Part 15. 8vo. 1898.
Manchester Literary and Philosophical Society —M.ev[xo\vs and Proceedings,

Vol. XLII. Part 2. 8vo. 1897-98.
Manchester Steam Users' Associatiom — Boiler Explosions Acts. Reports, Nos. 957-

1036. fol. 1897.
Meteorological Society, Royal — Meteorological Record, No. 67. 8vo. 1898.

Quarterly Journal, No. 106. 8vo. 1898.
Navy League — Navy League Journal for May, 1898. 4to.
Numismatic Society — Chronicle and Journal, 1898, Part L 8vo.
Odontological Society of Great Britain — Transactions, Vol. XXX. Nos. 6, 7. 8vo.

1898.
Paris, Societe Fran(;aise de Physique — Seances, 1897, Fasc. 3. 8vo.

Bulletin, Nos. 114-116. 8vo. 1898.
Pharmaceutical Society of Great Britain — Journal for May, 1898. 8vo.
Phillips, Charles E. S. Esq. M.R.I. — Submarine Telegraphs: Their History,

Construction and Working, By C. Bright. 8vo. 1898.
Photographic Society of Great Britain, Royal — The Photographic Journal for

April, 1898. 8vo.
Rochechouart, La Societe les Amis des Sciences at Arts — Bulletin, Tome VII.

Nos. 4-6. 8vo. 1897-98.
Rome, Ministry of Public Works — Giornale del Genio Civile, 1898, Fasc. 2, 3.

8vo. 1898.
Royal Society of London — Philosophical Transactions, Vol. CXCI. A, Nos. 216-

218. 4to. 1898.
Proceedings, Nos. 393-395. 8vo. 1898.
Saxon Society of Sciences, Royal —
Philologisch-Historische Classe —

Berichte, 1898, No. 1. 8vo.
Selborne Society — Nature Notes for May, 1898. 8vo.
Society of Arts — Journal for May, 1898. 8vo.
Tacchini, Prof. P. Hon. 3fem. R.I. (the Author) — Memorie della Societa degli

Spettroscopisti Italiani, Vol. XXVII. Disp. 3. 4to. 1898.
Tasmania, Royal Society of — Papers and Proceedings for 1897. 8vo. 1898.
Teyler Museum, Haarlem — Archives, Ser. II. Vol. V. Part 4; Vol. VI. Part 1.

8vo. 1898.
Thorpe, W. G. Esq. (the Author) — The Hidden Lives of Shakespeare and Bacon.

8vo. 1897.
Toulouse. Socie'te Archeologique du Midi de la France — Bulletin, Series in 8vo,

No. 20. 8vo. 1897.
United Service Institution, Royal — Journal for May, 1898. 870.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1898,

Heft 4, 5. 4to.
Vienna, Geological Institute, Imperial — Verhandlungen, 1898, Nos. 3-8. 8vo.
Whitworth, The Rev. William A. M.A. M.R.I, (the Author)— The Expectation of

Parts, into which a magnitude is divided at ran<lom. 8vo. 1898.
Zoological Society of London— Froceedmgs, 1897, Part 4. 8vo. 1898.

786 The Bight Eon, Lord Bayleigh [June 10,

WEEKLY EVENING MEETING,

Friday, June 10, 1898.

SiE William Huggins, K.C.B. D.C.L. LL.D. F.R.S. Vice-President,

in the Chair.

The Eight Hon. Lord Eayleigh, M.A. D.C.L. LL.D. F.R.S. M.B.I.

Professor of Natural Philosophy, B.I.

Some Experiments with the Telephone.

Early estimates of the minimum current of suitable frequency
audible in the telephone having led to results difficult of reconcilia-
tion with the theory of the instrument, experiments were undertaken
to clear up the question. The currents were induced in a coil of
known construction, either by a revolving magnet of known mag-
netic moment, or by a magnetised tuning-fork vibrating through
a measured arc. The connection with the telephone was completed
through a resistance which was gradually increased until the residual
current was but just easily audible. For a frequency of 512 the
current was found to be 7 X 10~^ amperes.* This is a much less
degree of sensitiveness than was claimed by the earlier observers,
but it is more in harmony with what might be expected upon
theoretical grounds.

In order to illustrate before an audience these and other experi-
ments requiring the use of a telephone, a combination of that
instrument with a sensitive flame was introduced. The gas, at a
pressure less than that of the ordinary supply, issues from a pin-
hole burner | into a cavity from which air is excluded (see figure).
Above the cavity, and immediately over the burner, is mounted a
brass tube, somewhat contracted at the top where ignition first
occurs. J In this arrangement the flame is in strictness only an
indicator, the really sensitive organ being the jet of gas moving
within the cavity and surrounded by a similar atmosphere. When
the pressure is not too high, and the jet is protected from sound, the
flame is rather tall and burns bluish. Under the influence of sound
of suitable pitch the jet is dispersed. At first the flame falls,

* The details are given in ' Phil. Mag.' vol. xxxviii. p. 285 (1894).
t The diameter of the pin-hole may be 0* 03".
X ' Camb. Proc.' vol. iv. p. 17, 1880.

1898.]

on Some Experiments with the Telephone

becoming for a moment almost
invisible ; afterwards it assumes
a more smoky and luminous ap-
pearance, easily distinguishable
from the unexcited flame.

When the sounds to be ob-
served come through the air,
they find access by a diaphragm
of tissue paper with which the
cavity is faced. This serves to
admit vibration while sufficiently
excluding air. To get the best
results the gas pressure must be
steady, and be carefully adjusted
to the maximum (about 1 inch)
at which the flame remains un-
disturbed. A hiss from the mouth
then brings about the transforma-
tion, while a clap of the hands or
the sudden crackling of a piece
of paper often causes extinction,
especially soon after the flame
has been lighted.

When the vibrations to be
indicated are electrical, the tele-
phone takes the place of the disc
of tissue paper, and it is advan-
tageous to lead a short tube from
the aperture of the telephone into
closer proximity with the burner.
The earlier trials of the combina-
tion were comparative failures,
from a cause that could not at
first be traced. As applied, for
instance, to a Hughes' induction
balance, the apparatus failed to
indicate with certainty the in-
troduction of a shilling into one
of the cups, and the performance,
such as it was, seemed to dete-
riorate after a few minutes' ex-
perimenting. At this stage an
observation was made which ulti-
mately afforded a clue to the
anomalous behaviour. It was
found that the telephone became
dewed. At first it seemed incre-
dible that this could come from

788 The Bight Hon. Lord Bayleigh [June 10,

the water of combustion, seeing that the lowest part of the flame was
many inches higher. But desiccation of the gas on its way to the
nozzle was no remedy, and it was soon afterwards observed that no
dewing ensued if the flame were all the while under excitation, either
from excess of pressure or from the action of sound. The dewing
was thus connected with the unexcited condition. Eventually it
appeared that the flame in this condition, though apparently filling
up the aperture from which it issues, was nevertheless surrounded
by a descending current of air carrying with it part of the moisture
of combustion. The deposition of dew upon the nozzle was thus
presumably the source of the trouble, and a remedy was found in
keeping the nozzle warm by means of a stout copper wire (not
shown) conducting heat downwards from the hot tube above.

The existence of the downward current could be made evident to
private observation in various ways, perhaps most easily by pro-
jecting little scraps of tinder into the flame, whereupon bright sparks
were seen to pass rapidly downwards. In this form the experiment
could not be shown to an audience, but the matter was illustrated
with the aid of a very delicate ether manometer devised by Professor
Dewar. This was connected with the upper part of the brass tube
by means of a small lateral perforation just below the root of the
flame. The influence of sound and consequent passage of the flame
from the unexcited to the excited condition was readily shown by
the manometer, the pressure indicated being less in the former state
of things.

The downward current is evidently closely associated with the
change of appearance presented by the flame. In the excited state
the gas issues at the large aperture above as from a reservoir at
very low pressure. The unexcited flame rises higher, and must
issue at a greater speed, carrying with it not only the material
supplied from the nozzle, and constituting the original jet, but also
some of the gaseous atmosphere in the cavity surrounding it. The
downward draught thus appears necessary in order to equalise the
total issue from the upper aperture in the two cases.

Although the flame falls behind the ear in delicacy, the combina-
tion is sufficiently sensitive to allow of the exhibition of a great
variety of interesting experiments. In the lecture the introduction
of a threepenny piece into one of the cups of a Hughes' induction
balance was made evident, the source of current being three
Leclanche cells, and the interrupter being of the scraping contact
type actuated by clockwork.

Among other experiments was shown one to prove that in certain
cases the parts into which a rapidly alternating electric current is
divided may be greater than the whole.* The divided circuit was
formed from the three wires with which, side by side, a large flat

* See 'Phil. Mag' vol. xxii. p. 490 (18SG).

1898.] on Some Exjyeriments with the Teleijhone. 789

coil is wound. One branch is formed by two of these wires connected
in series, the other (in parallel with the first), by the third wire.
Steady currents would traverse all three wires in the same direction.
But the rapidly periodic currents from the interrupter distribute
themselves so as to make the self-induction, and consequently the
magnetic field, a minimum ; and this is effected by the assumption of
opposite values in the two branches, the ratio of currents being as
2 : — 1. On the same scale the total or main current is + 1. It
was shown by means of the telephone and flame that the current in
one branch was about the same (arithmetically) as in the main, and
that the current in the other branch was much greater. [R.J

GENERAL MONTHLY MEETING,

Monday, July 4, 1898.

Sir James Criohton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Special Thanks of the Members were returned for the
following Donations to the Fund for the Promotion of Experimental
Research at Low Temperatures : —

£

Sir Frederick Abel, Bart. K.C.B 100

Sir Andrew Noble, K.C.B 100

Sir John Brunner, Bart. M.P. .. .. 50

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

The Lords of the Admiralty — Greenwich Observations, 1895. 4to. 1807.
(Greenwich Spectroscopic and Photographic Results, 1895. 4to. 1897.
Cape Meridian Observations, 1892 to 1895. 4to.

The Cape Photographic Durchmusterung for the Equinox, 1875, Vol. II. 4to.
Annals of the Cape Observatory, Vol. IV. 4to.
Report of the Astronomer-Royal to the Board of Visitors, 1898. fol.
Tfie British Museum Trustees — Facsimiles from Early Printed Books in the

British Museum, fol. 1897.
Catalogue of the Stowe MSS. Vol. I. Text ; Vol. II. Index. 8vo, 1895-96.
Catalogue of Greek Coins: Ionia (1892) ; Mysia(1892); Alexandria and the

Nomes (1892) ; Troas, ^olis and Lesbos (1894) ; Caira, Cos, Rhodes, &o.

(1897) ; Lycia, Pamphylia and Pisidia (1897). 8vo.
Catalogue of the Hindi, Panjabi, Sindhi and Pushtu Printed Books. 4to.

1893.
Catalogue of Hebrew Books acquired during 1868-92. 4to. 1894.
Ahurrow, Charles, Esq. M. Inst. C.E. {the Compiler) — Annual Eeport relating to

the Public Works Department of the Stadsraad, Johannesburg, S.A.R. "fol.

1897.

Vol. XY. (No. 92.) 3 f

790 General Monthly Meeting. [July 4,

Accademia dei Lincei, Beale, Roma — Classe di Scienze Morali, etc. : Rendiconti.

Serie Quinta, Vol. VII. Fasc. 3, 4. Classe di Scienze Fisiche, Matematiche

e Naturali. Atti, Serie Quinta : Rendiconti. 1° Semestre, Vol. VII. Fasc. 10.

8vo. 1898.

Agricultural Society, Royal— J nnrnal, Vol. IX. Part 2. 8vo. 1898.

American Academy of Arts and Sciences— Froceedmi::s, Vol. XXXIII. Nos. 9-12,

8vo. 1898.
American Philosophical Society— Vroceedings, Vol. XXXVI. No. 150. 8vo.

1897.
Anonymous — A Correspondence between an Amateur and a Professor of Political

Economy. 8vo. 1898.
Astronomical Society, Royal — Monthly Notices, Vol. LVIII. No. 7. 8vo. 1898,
Bankers, Institute o/— Journal, Vol. XIX. Part 6, 8vo. 1898.
Boston Public Library— Monthly Bulletin, Vol. III. No. 6. 8vo. 1898.
Boston Society of Natural History— Froceed'mgs, Vol. XXVIII. Nos. G, 7. 8vo.
1898
Memoirs, Vol. V. No. 3. 4to. 1898.
British Architects, Royal Institute o/— Journal, 3rd Series, Vol. V. Nos. lo, 16.

4to. 1898.
British Astronomical Association— 'Jonrao}, Vol. VIII. No. 7. Svo. 1898.
California, University o/^Various Publications, 1896-97.
Cambridge Observatory Sijudicate — Astronomical Observations made at the

Observatory, Vol. XXIII. 1872-7.5. 4to. 1S98.
Cambridge Philosophical Society— Froceedings, Vol. IX. Part 8. 8vo. 1898.
Cambridge University Library Syndicate — Annual Report, 1897. fol.
Camera Club — Journal for June, 1898. 8vo.

Chemical Industry, Society of — Journal, Vol. XVII. No. 5. 8vo. 1898.
Chemical Society — Journal for June, 1898. Svo.

Proceedings, Nos. 196, 197. Svo. 1897.
Chicago, Field Columbian Museum — Bulletins: Botanical Series, Vol. I. No. 4;
Anthropoloirical Series, Vol. II. No. 2 ; Zoological Series, Vol. I. Nos. 9, 10.
Svo. 1898.^
Clowes, Frank, Esq. F.C.S. M.R.I, (the Author)— The Detection and Measure-
ment of Inflammable Gas and Vapour in the Air. By F. Clowes and
B. Redwood. Svo. 1896.
A Treatise on Practical Chemistry and Qualitative Analysis. 6th ed. Svo.

1895.
Quantitative Chemic.d Analysis. By F. Clowes and J. B. Coleman. Svo.
1897.
Constable, Messrs. T. and A. (the Publishers) — The twenty-sixth volume of the
Publications of the Scottish History Society, containing "Diary of Lord
Wariston," "Preservation of the Honours of Scotland," "Lord Mar's
Legacies," "Highland Affairs in the 18th Century." Svo. 1896.
Cnrnivall, Royal Institution o/— Journal, Vol. XIII. Part 3. Svo. 1898.
Editors— American Journal of Science for June, 1898. Svo.
Analyst for June, 1898. Svo.

Anthony's Photographic Bulletin for June, 1898. Svo.
Athenseum for June, 1898. 4to.
Author for June, 1898. Svo.
Bimetallist for June, 1898. Svo.
Brewers' Journal for June, 1898. Svo.
Cbemical News for June, 1898. 4to.
Chemist and Druggist for June, 1898. Svo.
Education for June, 1898.
Electrical Engineer for June, 1898. fol.
Electrical Engineering for June 15, 1898. Svo.
Electrical Review for June, 1898. Svo.
Electricity for June, 1898. Svo.
Engineer for Juue, 1898. fol.

1898.] General Monthly Meetimj. 791

Editors — continued.

Engineering for June, 1898. fol.
Homoeopathic Review for June, 1898. 8vo.

Horological Journal for Dec. 1895, March ami Nov. 1897, and June, 1898. 8vo.
Industries and Iron for June, 1898. fol.
Invention for June, 1898.

Journul of Physical Chemistry for June, 1898. 8vo.
Journal of State Medicine for June, 1898. 8vo.
Law Journal for June, 1898. 8vo.
Lightning for June, 1898. 8vo.
Machinery Market for June, 1898. 8vo.
Nature for June, 1898. 4to.
New Church Magazine for June, 1898. 8vo.
Nuovo Cimento for May, 1898. 8vo.
Photographic News for June, 1898. 8vo.
Physical Review for May- June, 1898. 8vo.
Public Health Engineer for June, 1898. 8vo.
Science Abstracts, Vol. I. Part 6. 8vo. 1898.
Science Siftings for June, 1898.
Travel for June, 1898. 8vo.
Tropical Agriculturist for June, 1898.
Zoophilist for June, 1898. 4to.
. Edwards, Percy J. Esq. (the Compiler) — History of Loudon Street Improvements,

1855-97. fol. 1898.
Electrical Engineers, Institution of — Journal, Vol. XXVII. No. 135. 8vo. 1898.
Florence, Biblioteca Nazionale Centnde — Bollettiuo, Nos. 298, 299. 8vo. 1898.
Franklin Institute — Journal for June, 1898. 8vo.

Geographical Society, Royal — Geographical Journal for June, 1898. Svo.
Geological Society — Quarterly Journal, No. 212. 8vo. 1897.
Imperial Institute — Imperial Institute Journal for June, 1898.
Johns Hopkins University — University Circulars, No. 135. 4to. 1898.

American Chemical Journal for June, 1898. Svo.
Jordan, Wm. L. Esq. M.R.I, {the Author) — The Admiralty Falsification of the

" Challenger " Record. 8vo. 1890.
Leicester, Free Public Libraries Committee — Twenty-seventh Annual Report,

1897-98. Svo.
London County Council Technical Education Board — Report of the Technical
Education Board for 1897-98. fol.
London Technical Education Gazette for June, 1898. fol.
Manchester Geological Society —Tmnsactions, Vol. XXV. Part IG. Svo. 1898.
Manchester Literary and Philosophical Society — Memoirs and Proceedings, Fourth

Series, Vol. IX. No. 2. Svo. 1894-95.
Mechanical Engineers, Institution of — Proceedings, 1897, Nos. 3, 4. Svo.
Meriden Scientific Association — Transactions, Vol, VIII. Svo. 1897-98.
Mersey Commissioners—ilQpovt on the present state of the Navigation of the

River Mersey, 1897. By Sir G. S. Nares. Svo. 1S9S.
Microscopical Society, Royal — Journal, 1898, Part 3. Svo.
Navy League — Navy League Journal for June, 1898. Svo.
New Jersey Geological Survey — The Physical Geography of New Jersey. By

R. D. Salisbury. Svo. 1898.
New South Wales, The Agent-General for — The Wealth and Progress of New

South Wales, 1896-97. By T. A. Coghlan. Svo. 1897.
North of England Institute of Mining and Mechanical Engineers — An Account of
the Strata of Northumberland and Durham as proved by Borings and
Sinkings. A-B. and L-R. Svo. 1878-87.
Onnes, Prof. H. K. — Communications from the Physical Laboratory at the Univer-
sity of Leiden, No. 41. Svo. 1898.
Paris, Societe de Physique — Bulletin, Nos. 117, 118. Svo. 1898.
Pharmaceutical Society of Great Britain — Journal for June, 1898. Svo.

3 F 2

792 General Monthly Meeting. [«Tuly 4,

Philadelphia, Academy of Natural Sciences — Proceedings, 1897, Part 3. 8vo. 1898.
Photographic Society, Royal— The Photographic Journal for May, 1898. 8vo.
Rome, Ministry of Public Works — Giornale del Genio Civile, 1898, Fasc. 4. 8vo.

And Designi. fol.
Royal Society of Edinburgh— Vroceedings, Vol. XXII. No. 1. 8vo. 1897-98.

transactions, Vol. XXXIX. Part 1. 4to. 1898.
Royal Society of London — Philosophical Transactions, Ser. A, Vol. CXCI. No.
219; Ser. B, Vol. CXO. No. 157. 4to. 1898.
Proceedings, Nos. 396-398. 8vo. 1898.
St. Petersburg, Academic Imperiale des Sciences — Memoires, Tome V. Nos, 6-13;

Tome VI. Nos. 1-3, 5. 8vo. 1897-98.
Sanitary Institute— J omnaA, Vol. XVII. Part 3. 8vo. 1896,
Scottish Microscopical Society — Proceedings, Vol. II. No. 2. 8vo. 1896-97.
Selborne Society — Nature Notes for June, 1898. 8vo.
Smithsonian Institution — A Catalogue of Earthquakes on the Pacific Coast, 1769-

1897. By E. S. Holdeu. (Smith, Misc, Coll.) 8vo. 1898.
Society of Arts — Journal for June, 1898. 8vo.
Tacchini, Prof. P. — Memorie della Societa degli Spettroscopisti Italiani, Vol.

XXVII. bisp. 4, 4to. 1898,
Tarleton^ Alfred H. Esq. M.R.I, (the Author)— 'Nicholas Breakspear (Adrian IV,),

Englishman and Pope. 4to. 1896.
United Service Institution, Royal — Journal for June, 1898. 8vo.
United States Department of Agriculture — Experiment Station Record, Vol. IX.
Nos, 8-10. 8vo, 1898.
Year Book of Agriculture, 1897. 8vo. 1898.
United States Department of the Interior — Report of the Secretary of the Interior,
1895-96, Vol, IV, Parts 1-4. 4to. 1896.
Report of the Secretary of the Interior, 1896. 5 vols. 8vo, 1896-97.
United States Patent O^ice— Official Gazette, Vol, LXXXIII. Nos. 2-5. 8vo.

1898.
University of Xondon— Calendar, 1898-99. 8vo. 1898,
Victoria Institute — Journal, No, 118. 8vo. 1898.

Vienna, Imperial Geological Institute — Jahrbuch, Band XLVII. Heft 2. 8vo,
1897.
Abhandlungen, Band XVII. Heft 4. 4to. 1897.
Wagner Free Institute of Science, Philadelphia — Transactions, Vol. V. 8vo, 1898.
Yorkshire Archxological Society — Yorkshire Archaeological Journal, Part 57. 8vo.
1898.
List of Members and Catalogue of Library, 8vo. 1898.
Zoological Society of London — Proceedings, 1898, Part 1. 8vo.

Transactions, Vol. XIV. Part 6. 4to. 1898,
Zurich, Naturforschende Gesellschaft — Vierteljahrsschrift der Naturforschenden
Gesellschaft, 1898, Heft 1. 8vo. 1898.

1898.] General Montlily Meeting. 793

GENERAL MONTHLY MEETING.

Monday, November 7, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

The Special Thanks of the Members were returned for the
following Donations to the Fund for the Promotion of Experimental
Research at Low Temperatures : —

John B. Carrington, Esq £25

Charles Scott Dickson, Esq. Q.C £100

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

The Lords of the Admiralty — Keport of Her Majesty's Astronomer at the Cape

of Good Hope for 1897. 4to. 1898.
Ahel, Sir Frederick, Bart. K.C.B. F.R.S. M.R.I. <&c.— Annual Keport of the

Indian Section of the Imperial Institute, 1897-98. fol. 1898.
Accademia dei Lincei, Reale, Roma — Classe di Scienze Morali, Storiehe e Filo-

logiehe : Rendiconti. Serie Quiuta, Vol. VII. Fasc, 5, 6. 8vo. 1898.
Atti, Serie Quinta : Rendiconti. Classe di Scienze Fisiche, etc. 1" Semestre,

Vol. VII. Fasc. 11, 12 ; 2° Semestre, Vol. VII. Fasc. 1-7. 8vo. 1898.
Agricultural Society of England — Journal, Vol. IX. Part 3. 8vo. 1898.
American Academy of Arts and Sciences— Proceedings, Vol. XXXII. Nos. 13-14.

8vo. 1897. Vol. XXXIII. Nos. 13-27 ; Vol. XXXIV. No. 1. 8vo. 1898.
Memoirs, Vol. XII. No. 4. 4to. 189 .
American Association for the Advancement of Science — Proceedings, Vol. XLVI.

8vo. 1898.
American Geographical Society — Bulletin, Vol. XXX. No. 3. 8vo. 1898.
American Philosophical Society — Proceedings, Vol. XXXVII. No. 157. 8vo. 1898.
Amsterdam, Royal Academy of Sciences — Verhandelingen, 1« Sectie, Deel VI.

Nos. 1-5 ; 2« Sectie, Deel VI. Nos. 1, 2. 8vo. 1898.
Jaarboek, 1897. 8vo. 1898.
Verslagen, Deel VI. 8vo. 1898.
Asiatic Society of ifengaZ— Proceedings, 1897, Nos. 9-11 ; 1898, Nos. 1-4. 8vo.
Journal, Vol. LXI. Part 1, Extra No. 3; Vol. LXVI. Part 1, No. 4, Part 2,

No. 4; Vol. LXVII. Part 1, No. 1. 8vo. 1897-98.
Asiatic Society, Royal — Journal for July-Oct. 1898. 8vo.
Astronomical Society, Royal— ^lonthly Notices, Vol. LVIII. Nos. 8, 9, and

Appendix. 8vo. 1898.
List of Members, June 1898. 8vo.
Bankers, Institute o/— Journal, Vol. XIX. Part 7. 8vo. 1898.
Basel, Naturforschende Gesellschaft—\ erhsindlungen, Band XII, Heft 1. 8vo.

1898.
Berlin, Royal Prussian Academy of Sciences — Sitzungsberichte, 1898, Nos. 24-39.

8vo.
Boston, U.S.A. Public Library — Monthly Bulletin of Books added to the Library,

Vol. III. Nos. 7-10. 8vo. 1898.
Forty-sixth Annual Report, 1897-98. 8vo.
Boston Society of Natural History — Proceedings, Vol. XXVIII. Nos. 8-12. 8vo.

1898.

794 General Monthly Meeting. [Nov. T,

Botanic Society of London, Royal — Quarterly Record, Vol. YII. No. 73. 8vo,

1898.
British Architects, Eoyal Institute o/— Journal, 1897-98, Nos. 17-20. 8vo.

Calendar, 1898-99. 8vo. 1898.
British Astronomical Association — Journal, Vol. VIIT. Nos. 8-10. 8vo. 1898.

Memoirs, Vol. VI. Parts 4, 5; Vol. A' II. Part 1. 8vo. 1898.
British Museum Trustees — The Poems of Bacchylides. Edited by F, G. Kenyon.
8vo. 1897.
The Poems of Bacchylides. Facsimile of Papyrus DCCXXXIII. in the

British Museum, fol. 1897.
Catalogue of Printed Books in the British Museum relating to Wm. Shake-
speare. 4to. 1897.
Supplement to the Catalogue of the Persian MSS. By C. Eieu. 4to. 1895.
White Athenian Vases. By A. S. Murray and A. H. Smith. 4to. 1896.
Facsimiles of Royal, Historical, Literary and other Autographs in the Depart-
ment of MSS. Edited by G. F. Warner. First Series, Second Edition, 1898 ;
Second Series, 1896 ; Third Series, 1897. fol.
Catalogue of Seals in the Department of MSS. Vol. V. 8vo. 1898.
Catalogue of Drawings by British Artists in the Department of Prints. By

L. Binyon. 8vo. 1898.
Catalogue of Japanese Printed Books and MSS. By R. K. Douglas. 4to.
1898.
Brymner, Douglas, Esq. {the Archivist) — Report on Canadian Archives for 1897.

8vo. 1898.
Buenos Aires, Museo Nacional — Comunicaciones, Tome I. No. 1. 8vo. 1898.
Camera Club — Journal for July-Oct. 1898. 8vo.

Campion, Henry, Esq. {the Author) — The Secret of the Poles. 8vo. 1898.
Canadian Institute — Transactions, Vol. V. Part 2, No. 10. 8vo. 1898.

Proceedings, Vol. I. Parts 4, 5. 8vo. 1898.
Chemical Industry, Society o/— Journal, Vol. XVII. Nos. 6-10. 8vo. 1898.
Chemical Society — Journal for July-Oct. 1898. 8vo.
Civil Engineers, Institution of — Minutes of Proceedings, Vols. CXXXII.

CXXXIII. 8vo. 1898.
Cocy The Rev. Charles C. (the Author) — Nature versus Natural Selection; an

essay on organic evolution. 8vo. 1895.
Collurania, Osservatorio privato di {Teramo) — Pubblicazioni : No. 1 (Marte uel

1896-97, by C. Cerulli). 8vo. 1898.
Colonial Institute, Royal — Proceedings, Vol. XXIX. 8vo. 1898.
Cornivall, Polytechnic Society, J2o?/aZ— Sixty-fifth Annual Report. 8vo. 1897.
Cracovie, V Academic des Sciences — Bulletin International, 1898, Nos. 4, 5. 8vo.
Crawford and Balcarres, The Earl of, K.T. ili.i?./.— Bibliotheca Lindesiana:
Catalogue of English Broadsides, 1505-1897. (Privately Printed.) 4to.
1898.
Collations and Notes, No. 4 : Autototype Facsimiles of Three Mappemondes.
1. The Harelian (or Anonymous) Mappemonde, c. 15.36; 2. The Mappe-
monde by Desceliers of 1546; o. The Mappemonde by Desceliers of 1550.
With Notes by C. H. Coote. (Privately Printed) 4to and fol. 1898.
List of MSS. Printed Books and Examples of Metal and Ivory Bindings. Two
Parts. 8vo. 1898;
Dax, Societede 5orda— Bulletin, 1898, Nos. 1, 2. 8vo.
East India Association— SomxuqX, Vol. XXX. Nos. 14, 15. 8vo. 1898.
Editors — Aeronautical Journal for July, 1898. 8vo. ^

American Journal of Science for July-Oct. 1898. 8vo.
Analyst for July-Oct. 1898. -8vo.

Anthony's Photographic Bulletin for July-Oct. 1898. 8vo.
Astrophysical Journal for June, Aug. Oct. 1898. 8vo.
Ateneo Veneto, Anno XX. Vol. I. Fasc. 2, 3 ; Vol. II. Fasc. 1-3 ; Vol. XXI.

Fasc. 1, 2. 8vo. 1897-98.
Athenaeum for July-Oct. 1898. 4to.

1898.] General Monthly Meeting. 795

Editors — contiimed.

Author for July-Oct. 1898.

Bimetallist for July-Oct. 1898.

Brewers' Journal for July-Oct. 1898. 8vo.

Chemical News for July-Oct. 1898. 4to.

Chemist and Druggist for July-Oct. 1898. 8vo.

Education for July-Oct. 1898. 8vo.

Electrical Engineer for July-Oct. 1898. fol.

Electrical Engineering for July-Oct. 1898.

Electrical Eeview for July-Oct. 1898. 8vo.

Engineer for July-Oct. 1898. fol.

Engineering for July-Oct. 1898. fol.

Homoeopathic Review for July-Oct. 1898.

Horological Journal for July-Oct. 1898. 8vo.

Industries and Iron for July-Oct. 1898. fol.

Invention for July-Oct. 1898. 8vo.

Journal of Physical Chemistry for Oct. 1898. 8vo.

Journal of State Medicine for July-Oct. 1898. 8vo.

Law Journal for July-Oct. 1898. 8vo.

Machinery Market for July-Oct. 1898. 8vo.

Nature for July-Oct. 1898. 4to.

New Church Magazine for July-Oct. 1898. 8vo.

Nuovo Cimento for June, 1898. 8vo.

Physical Eeview for July- Aug. 1898. 8vo.

Public Health Engineer for July-Oct. 1898. 8vo.

Science Abstracts, Vol. I. Parts 7, 8. 8vo. 1898.

Science Siftings for Aug. 1898. 8vo.

Terrestrial Magnetism for June, 1898. 8vo.

Travel for July-Oct. 1898. 8vo.

Tropical Agriculturist for July-Oct. 1898. 8vo.

Zoophilist for July-Oct. 1898. 4to.
Electrical Engineers, Institution o/— Journal, Vol. XXVII. No. 136. 8vo. 1898.

List of OflScers and Members. 8vo. 1898.
Emigrants^ Information Office — Circulars on Canada, the Australasian and South

African Colonies, July-Oct. 1898. 8vo.
Florence, Biblioteca Nazionale Centrale—BoWeiuio, Nos. 300-308. 8vo. 1898.
Florence, lieale Accademia dei Georgofili — Atti, Vol. XX. Disp. 3, 4 ; Vol. XXI.

Disp. 1, 2. 8vo. 1897-98.
Franklin Institute— Journal for July-Oct. 1898. 8vo.

Garrard, J. J. Esq. (the Commissioner) — Report on the Mining Industry of Zulu-
land for 1897. fol. 1898.
Geographical Society, Roijal — Geographical Journal for July-Oct. 1898. 8vo.

Antarctic Exploration : A plea for a National Expedition. By Sir C. E.
Markham. 8vo. 1898.

Historical Atlas of the Chinese Empire. By E. L. Oxenham. 2nd edition.
4to. 1898.

Notes on the Kuril Islands. By H. J. Snow. 8vo. 1897.

Supplement to the Bibliography of Algeria, 1895. By Lieut.- Col. R. L. Play-
i\iir. 8vo. 1898.

The Pamirs and the Source of the Oxus. By Et. Hon. G. N. Curzon. 8vo.
1898.
Geological Societij—Qusntexly Journal, No. 215. 8vo. 1898.
Glasgow, Philosophical Society— Proceedings, Vol. XXIX. 8vo. 1898.
Harlem, Societe Hollandaise des Sciences — ^Archives Ne'erlandaises, Ser. II.

Tome II. Livr. 1. 8vo. 1898.
Horticultural Society, Royal— J onrnsi], Vol. XXI. Part 2 ; Vol. XXII. Parts 1, 2.

8vo. 1897-98.
Howard Association — Ecport, October 1898. 8vo.
Illinois State Laboratory of Natural History— BnWetiu, Vol. V. Nos. 4, 5. 8vo. 1898.

796 General Monthly Meeting. [Nov. 7,

Imperial Institute — Imperial Institute Journal for July-Oct. 1898.

Imperial Institute Year Book, 1894; aud Supplement, 1895. 8vo.
Iron and Steel Institute — Journal, 1898, No. 1. 8vo.

Johns Hopldns University — American Chemical Journal for July-Oct. 1898. 8vo.
American Journal of Philology, Vol. XIX. No. 2. 8vo. 1898.
University Circulars, No. 136. 4to. 1898.

University Studies, 14 th Series, Nos. 8-10 ; 15th Series, Nos. 3-12 ; 16th Series,
Nos. 1-5. 8vo. 1896-98.
Jordan, James B. ^£"52. —Raised Geological Model of London and Suburbs. By

J. B. Jordan.
Le Creps, Arthur, Ei-q. (the Author) — A Hospital Steam Ship for Wrecked Fisher-
men. 8vo. 1898.
Leeds Philosophical and Literary Society— ^eyenty-eighth. Annual Report. 8vo.

1898
lAnnean i^oae^y- Journal, Nos. 171, 232, 233. 8vo. 1898.

Transactions: Zoology, Vol. VII. Part 4; Botany, Vol. V. Parts 7,8. 4to.
1897-98.
London County Council Technical Education Board — London Technical Educa-
tion Gazette for July-Oct. 1898. 8vo.
MacClean, Frank, Esq. F.R.S. M.R.L (the Author)— Spectra of Southern Stars,
with tables and plates. 4to. 1898.
Comparative Photographic Spectra of Stars to the 3^ magnitude. (Phil. Trans.)
4to. 1898.
Madras Government iT/Mseum— Bulletin, Vol. II. No. 2. Anthropology. 8vo. 1898.

Administrative Report for 1897-98. fol.
Manchester Geological Society — Transactions, Vol. XXV. Parts 17-21. 8vo.

1898.
Manchester Literary and Philosophical Society— Memo'uB and Proceedings,

Vol. XLII. Parts 3, 4. 8vo. 1897-98
Manchester Museum, Owens College — The Nomenclature of the Seams of the
Lancashire Lower Coal Measures. 8vo. 1898.
Report for 1897-98. 8vo.
Massachusetts Institute of Technology— Technology Quarterly, Vol. XI. No. 2.

8vo. 1898.
Mechanical Engineers, Institution of — Proceedings, 1898, Nos. 1, 2.
Meteorological Society, Royal — Meteorological Record, No. 68. 8vo. 1898.

Quarterly Journal, No. 107. 8vo. 1898.
Metropolitan Asylums Board — Report for 1897. 8vo. 1898.
Mexico, Sociedad Cientifica " Antonio Alzate " — Memorias y Revistas, Tomo XI.

Nos. 1-8. 8vo. 1897-98.
Microscopical Society, Royal— Journal, 1898, Parts 4, 5. 8vo.
Munich, Royal Bavarian Academy of Sciences — Sitzungsberichte, 1898, Heft 2.

8vo. 1898.
Musical Association — Proceedings, Twenty-fourth Session, 1897-98. 8vo. 1898.
Navy League — Navy League Journal for July-Oct. 1 898. 4to.

Minutes of Proceedings at tlie Navy League Conference to consider the posi-
tion of this country if involved in v/ar. 8vo. 1898.
New Jersey, Geological Survey of — Relief Map of New Jersey, 1896. fol.

Annual Report of State Geologist for 1897. 8vo. 1898.
New York Academy of Sciences— Anna.la,\ol. XI. Fart 1. 8vo. 1898.

Transactions, Vol. XVI. 8vo. 1898.
Norfolk and Norwich Naturalists' Society — Transactions, Vol. VI. Part 4. 8vo. 1898.
North of England Institute of Mining and Mechanical Engineers — Transactions,

Vol. XLVIL Parts 4, 5. 8vo. 1898.
Numismatic Society — Chronicle and Journal, 1898, Parts 2, 3. 8vo.
Odontological Society of Great ^r/^a wt— Transactions, Vol. XXX. No. 8. 8vo

1898.
Palestine Exploration F«nd— Excavations at Jerusalem, 1894-97. By F. J. Bliss.
8vo. 1898.

1898.] General MontMy Meeiinj, 797

Paru, Sociefe Fran^aise de Physique — Seances, 1897, Fase. 4. 8vo.

Bulletin, Nos. 119, 120. 8vo. 1898.
Patent Offi.ce — Catalogue of the Library of the Patent OflSce. Vol. I. Authors. 4to.

1898.
Pharmaceutical Society of Great Britain — Journal for July-Oct. 1898. 8vo.
Philadelphia, Academy of Natural Sciences — Proceedings, 1898, Part 1. 8vo.
Photographic Society of Great Britain, Royal — The Photographic Journal for

June-Oct. 1898. 'Svo.
Physical Society of London — Proceedings, Vol. XVI. Nos. 1, 2. Svo. 1898.

List of Fellows. 8vo. 1898.
Pitt-Rivers, Lieut-Gen. D.C.L. F.R.S. F.S.A. M.R I. (the Author)— Exc&valious

in Craiiborne Chase, Vol. IV. (Printed Privately.) 4to. 1898.
Prince, C. L. Esq. F.R.A.S. (the Author) — Observations upon the Topography and

Climate of Crowborough Hill. 2iid edition. 8vo. 1898.
Quehett Microscopical C/tt6— Journal, Series II. Nos. 39-42. Svo. 1896-98.
Rio de Janeiro, Museo Nacional — Kevista, Vol. I. 4to. 1896.
Rio de Janeiro, Observatorio — Annuario for 1898. Svo. 1897.
Rochechouart, La Societe les Amis des Sciences et Arts — Bulletin, Tome VIII.

Nos. 1, 2. Svo. 1898.
Rome, Ministry of Public TForA-s— Giornale del Genio Civile, 1898, Fasc. 5. Svo.

1898.
Royal College of 5'»rgfeows— Calendar, 1898. Svo.

Royal Irish Academy — Proceedings, 3rd Series, Vol. IV. No. 5. Svo. 1898.
Royal Societies Club — " The Royal Societies Clnb " : Foundation, Objects, Rules,

Bye-Laws, List of Members. Svo. 1897.
Royal Society of Edinburgh— TTansaciions, Vol. XXXVIII. Part 3. 4to. 1896.
Royal Society of London — Philosophical Transactions, Vol. CXOI. A, Nos. 220-225 ;

Vol. CXCI. B, Nos. 158, 159. 4to. 1898.
Proceedings, Nos. 399-403. Svo. 1898.
Royal Society of Neio South TFaZes — Journal and Proceedings, Vol. XXXI. Svo,

1898.
St. Bartholomew's Hospital—Bejiorts, Vol. XXXIII. Svo. 1898.
St. Petersburg, V Academic Imperiale des Sciences — Bulletin, V«* Serie, Tome VIL

Nos. 2-5 ; Tome VIII. Nos. 1-4. Svo. 1897-98.
Me'moires, Tome VI. Nos. 4, 6-8, 10. 4to. 1898.
Sanitary Institute— J ouma\. Vol. XIX. Part 2. Svo. 1898.
Saxon Society of Sciences, Royal —
Philologisch • Historisch e Classe —

Abhandlungen, Band XVIL No. 2. Svo. 1898.

Berichte, 1898, Nos. 2, 3. Svo.
Mathematisch-Physische Classe —

Abhandlungen, Band XXIV. Nos. 4, 5. Svo. 1898.

Berichte, 1898, Nos. 1-4. Svo.
Scottish Meteorological Society — Journal, Third Series, Nos. 13, 14. Svo. 1898.
Selborne Society — Nature Notes for July-Oct. 1898. Svo.
Smithsonian Institution — A Catalogue of Scientific and Technical Periodicals,

1665-1895. By H. C. Bolton. 2nd edition. Svo. 1897. (Smith. Miss.

Coll. 1096.)
Report of U.S. National Museum for 1895. Svo. 1897.
Society of ^rfs— Journal for Jnly-Oct. 1898. Svo.
Statistical Society, jRo?/aZ— Journal, Vol. LXI. Parts 2, 3. Svo. 1898.
Swedish Academy of Sciences, ^o?/aZ —Bihang, Band XXIII. Heft 1-4. Svo. 1898.

Ofversigt, Band LIV. Svo. 1898.
Tacchini, Prof. P. Hon.Mem.R.L {the Author) — Memorie della Societa degli Spet-

troscopisti Italiani, Vol. XXVII. Disp. 5-8. 4to. 1898.
Toulouse, Socie'te Archeologique du Midi de la France — Bulletin, Series in Svo,

No. 21. Svo. 1898.
Tuer, Andreio W. Esq. (the Author) — Bartolozzi and his Works. 2nd edition.

Svo. 1885.

798 General Monthly Meeting, [Nov. 7,

United Service Institution, Boyal — Journal for July-Oct. 1898. 8vo.
United States Department of Agriculture — Experiment Station Bulletin, Nos. 52,
53. 8vo. 1898.
Experiment Station Record, Vol. IX. No. 11 ; Vol. X. No. 1. 8vo. 1898.
Division of Chemistry, Bulletin, No. 50. 8vo. 1898. '
Biological Survey, Bulletins, Nos. 1-11. 8vo. 1898.
United States Department of the Interior (Census O^ce)— Compendium of the
Eleventh Census, 1890, Part 3. 4to. 1897.
Eeport on Vital and Social Statistics at the Eleventh Census, Part 1. 4to.

1896.
Report on Population, Part 2. 4to. 1897.

Statistical Atlas of the United States based upon results of the Eleventh
Census, fol. 1898.
United States Geological ^SMrt-e?/— Geological Atlas of the United States, Folios

26-37. fol. 1896-97.
United States Patent O^^ce— Official Gazette, Vol. LXXXIII. Nos. 6-13; Vol.

LXXXIV. Nos. 1-13; Vol. LXXXV, Nos. 1-4. 8vo. 1898.
Upsal, Royal Society of Sciences — Nova Acta, Vol. XVII. Fasc. 2. 4to. 1898.
Verein zur Beforderung des Gewerhfleisses in Preussen — Verhandlungen, 1898,

Heft 6-8. 4to.
Ver non-Ear court, L. F. Esq. M.Inst.C.E. {the Author) — Formulary of the charac-
teristic particulars about a Tidal River. 8vo. ' 1898.
Victoria Institute— 3 onm&X, Nos. 119, 120. 8vo. 1898.
Vienna, Imperial Geological Institute — Verhandlungen, 1898, Nos. 9-12. 8vo.

Jahrbuch, Band XLVII. Heft 3, 4 ; Band XL VIII. Heft 1. 8vo. 1898.
Vincent, Benjamin, Esq. Hon.Lih. Roy. Inst, (the Compiler) — Haydn's Dictionary

of Dates. 22hd edition. 8vo. 1898.
Yale University Observatory— Eeiwri, 1897-98. 8vo.
Zoological Society of London — Proceedings, 1898, Parts 2, 3. 8vo. 1898.

Transactions, Vol. XIV. Part 7. 4to. 1898.
Ziirich, Naturforschende Gesellschaft — Vierteljahrsschrift, 1898, Heft 2, 3. 8vo.
1898.

1898.J General Monthly Meeting. 799

GENERAL MONTHLY MEETING,

Monday, December 5, 1898.

Sir James Cbichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

Herbert William Allingham, Esq., F.R.C.S.

T. Newbold Piddocke, Esq.

Edward Preedy, Esq.

William Munro Tapp, Esq. LL.D.

The Hon. William Frederick Ciithbert Vernon,

Mrs. Adela Wetzlar,

Charles Theodore Williams, M.A. M.D. F.R.C.P.

were elected Members of the Eoyal Institution.

The Special Thanks of the Members were returned to Dr. George
Wyld for his present of a Portrait of Dr. Thomas Garnett, the first
Professor in the Eoyal Institution.

The Presents received since the last Meeting were laid on the
table, and the thanks of the Members returned for the same, viz. : —

FROM

Accademia dei Lincei, Reale, Eoma — Classe di Scienze Fisiche, Matematiche e

Natural!. Atti, Serie Quinta : Kendiconti. 2" Semestre, Vol. VII. Fasc. 8, 9,

8vo. 1898.
American Geographical Society — Bulletin, Vol. XXX. No. 4. 8vo. 1898.
Asiatic Societtj of Bengal — Journal, Vol. LXVIi. Fart 1, Nos. 2, 3; Part 2, Nos.

1, 2 ; Part 3, No. 1.
Proceedings, 1898, Nos. 5-8. 8vo.
Australian Museum, Sydney — Keport of Trustees for 1897. fol. 1897.
Bankers, Institute o/— Journal, Vol. XIX. Part 8. 8vo. 1898.
Bashforth, The Rev. Francis, 5.1).— Keplica di Krupp all Protesta del Signer

iiashforth. Translated, with Notes. 8vo. 1898.
Boston Public Library— Monthlj Bulletin, Vol. HI. No. 11. 8vo. 1898.
British Architects, Rotjal Institute o/— Journal, 3rd Series, Vol. VI. Nos. 1, 2. 4to

1898.
British Astronomical Association— J ourna], Vol. IX. No. 1. 8vo. 1898.
Cambridge Philosophical Society — Transactions, Vol. XVII. Part 1. 4to. 1898.

Proceedings, Vol. IX. Part 9. 8vo. 1898.
Camera Club — Journal for Nov. 1898. 8vo.
Canada, Royal Society o/— Proceedings and Transactions, 2ud Series, Vol. III.

8vo. 1897.
Chemical Society— Journal for Nov. 1898. 8vo.

Proceedings, Nos. 198, 199. 8vo. 1897.
Chicago, Field Columbian Museum — Bulletins: Anthropological Series, Vol. II,

No. 3. 8vo. 1898.
Civil Engineers, Institution of — Minutes of Proceedings, Vol. CXXXIV. 8vo,

1898.
Clinical Society of London— Trsmsactions, Vol. XXXI. 8vo. 1898.
Cracovie, T Academic des Sciences — Bulletin International, 1898, No. 8. 8vo,

800 General Monthly Meeting. [Dec. 5,

Devonshire Asi^ociation— 'Report and Transactions, Vol. XXX. 8vo. 1898.
Editors — American Journal of Science for Nov. 1898. 8vo.

Analyst for Nov. 1898. 8vo.

Anthony's Photographic Bulletin for Nov. 1898. 8vo.

Athenseum for Nov. 1898. 4to.

Author for Nov. 1898. Svo.

Aeronautical Journal for Oct. 1898. Svo.

Bimetallist for Nov. 1898. 8vo.

Brewers' Journal for Nov. 1898. Svo.

Chemical News for Nov. 1898. 4to.

Chemist and Druggist for Nov. 1898. Svo.

Education for Nov. 1898.

Electrical Engineer for Nov. 1898. fol.

Electrical Engineering for Nov. 1898. Svo.

Electrical Keview for Nov. 1898. Svo.

Electricity for Nov. 1898. Svo.

Engineer for Nov. 1898. fol.

Engineering for Nov. 1898. fol.

Homoeopathic Keview for Nov. 1898. Svo.

Horological Journal for Nov. 1898. Svo.

Industries and Iron for Nov. 1898. fol.

Invention for Nov. 1898.

Journal of State Medicine for Nov. 1898. Svo.

Law Journal for Nov. 1898. Svo.

Lightning for Nov. 1898. Svo.

Machinery Market for Nov. 1898. Svo.

Nature for Nov. 1898. 4to.

New Ciiurch Magazine for Nov. 1898. Svo.

Nuovo Cimento for Aug. 1898. Svo.

Photographic News for Nov. 1898. Svo.

Physical Review for Sept.-Oct. 1898. Svo.

Public Health Engineer for Nov. 1898. Svo.

Science Abstracts, Vol. I. Part 11. Svo. 1898.

Science Siftings for Nov. 1898.

Terrestrial Magnetism for Sept. 1898. Svo.

Travel for Nov. 1898. Svo.

Tropical Agriculturist for Nov. 1898.

Zoophilist for Nov. 1898. 4to.
Florence, Bihlioteca Nazionale Centrale — Bollettino, No. 310. Svo. 1898.
Franklin Institute— J ournaA for Nov. 1898. Svo.

Geographical Society, Royal — Geographical Journal for Nov. 1898. Svo.
Geological Society — Quarterly Journal, No. 216. Svo. 1898.
Gill, L. Upcott, Esq. (the Publisher) — The Naturalists' Directory for 1898. Svo.
Historical Society, Royal — Transactions, Vol. XII. Svo. 1898.
Imperial Institute — Imperial Institute Journal for Nov. 1898.
Johns Hopkins University — American Chemical Journal for Nov. 1898. Svo.
Junior Engineers, Institution of — Record of Transactions, Vol. VII. Svo. 1898.
Linnean Society of London— Froceedings, Nov. 1897 — June 1898. Svo. 1898.

Journal, Nos. 234, 235. Svo. 1898.
Liverpool, Literary and Philosophical Society — Proceedings, Vol. LII. Svo. 1898.
Madras Observatory— Report for 1897-98. Svo. 1898.
Makato, Tentearo (the Author) — Japanese Notions of European Political Economy.

Svo. 1898.
Manchester Free Libraries Committee — Forty-sixth Annual Report. Svo. 1897-98.
Massachusetts Institute of Technology — Teclinology Quarterly for Sept. 1898. Svo.
Meteorological Society, Royal — Meteorological Record, Nos. 69, 70. Svo. 1898.

Quarterly Journal, No. 108. Svo. 1898.
Munich, Royal Bavarian Academy of Sciences — Sitzungsberichte, 1898, Heft 3.
Svo.

1898.] General MontJdij Meeting. 801

Navy League— 'N&Yj League Journal for Nov. 1898. 8vo.

New York Academy of Sciences — Annals, Vol. XI. Part 2. 8vo. 1898.

Onnes, Prof. H. K. — Communications from the Physical Laboratory at the Univer-
sity of Leiden, Nos. 27, 36, 42, 43. 8vo. 1898.

Paris, Society Frangaise de Physique — Bulletin, Nos. 121, 122. 8vo. 1898.
Seances, 1898, Fasc. 1. 8vo.

Pharmaceutical Society of Great Britain — Journal for Nov. 1898. 8vo.

Quekett Microscopical Oiu&— Journal, Vol. VII No. 48. 8vo. 1898.

Rome, Ministry of Public IFbrfes —Giornale del Geaio Civile, 1898, Fasc. 6, 7. 8vo.
And Designi. fol.

Royal Society of Edinburgh— Proceed'mgs, Vol. XXII. No. 2. 8vo. 1897-98.

Royal Society of Low^Zow— Philosophical Transactions, Ser. A, Vol. CXCl. Nos.
226, 227 ; Ser. B, Vol. CXC. Nos. 160-166. 4to. 1898.

Sanitary Institute— J onrudl. Vol. XIX. Part 3. 8vo. 1898.

Saxon Society of Sciences, Royal —
Philologisch-historische Classe —
Abhandlungen, Band XVIII. No. 3. 8vo. 1898.
Sachregister der Abhandlungen und Berichte, 1846-1895. 8vo. 1898.

Selborne Society— ^atnTe Notes for Nov. 1898. 8vo.

Smithsonian Institution — An Investigation on the influence upon the vital resist-
ance of animals to the micro-organisms of disease brought about by prolonged
sojourn in an impure atmosphere. By D. H. Bergey. Hodgkius Fund Essay.
(Smithsonian Misc. Coll. 1125.) 8vo. 1898.
A determination of the ratio (x) of the Specific Heats at constant pressure and
at constant volume for air, oxygen, carbon dioxide and hydrogen. Hodgkins
Fund Essay. (Smithsonian Cont. to Knowledge, 1126.) 4to. 1898.
Smithsonian Report for 1896. Excerpts: Nos. 1097, 1098, 1102, 1114. 8vo.
1898.

Society of Arts — Journal for Nov. 1898. 8vo.

Sweden, Academy of Sciences — Handlingar, Band XXX. 4to. 1897-98.

Thompson, Professor Silvanus P. D.Sc. F.R.S. M.R.L {the ^w^/ior)— Michael
Faraday : His Life and Work. (The Century Science Series.) 8vo. 1898.

United Service Institution, Roijal- J ournoX for Nov. 1898. 8vo.

United States Department of Agriculture— lS,x^eriment Station Record, Vol. IX.
No. 12; Vol. X. No. 2. Svo. 1898.

United States Patent O^ce— Annual Report of the Commissioner of Patents for
1897. Svo. 1898.
Official Gazette, Vol. LXXXV. Nos. 5-8. Svo. 1898.
Vienna, Imperial Geological Institute — Verhandlungen, 1898, No. 13. Svo.

Yorkshire Archxdogical Society— Yorkshire Archoeological Journal, Part 58. Svo.
1898.

802 Captain Ahney [Fob. 25.

WEEKLY EVENING MEETING,

Friday, February 25, 1893.

Sir Frederick Abel, Bart. K.C.B. D.C.L. LL.D. F.R.S.
Vice-President, in the Chair.

Captain Abney, C.B. D.C.L. F.R.S. 3IM.L

The Theory of Colour Vision applied to Modern Colour Photography,

The subject of my address this evening is a very large one, and
would occupy moie time than the hour allotted to me, if I entered
fully into every part of it. All I can hope to do is to jiut before you
the main scientific reasoning which has led to the success at present
attained in colour photograj)hy, by a combination of colours, aud
by the absorption of colouring matter.

On the screen we have the sjiectrum of the electric light, and a
very beautiful object it is. But it is not to its beauty that 1 wish to
call your attentiou, but to the varying brightness of its different
parts, and further, to the fact that in it we have strictly pure colours,
that is a series of simple colours, and not mixed colours such as we
may find in nature. Now if we can reproduce fairly well by means
of photography this grand multi-coloured band, both as regards
colour and also brightness (that is luminosity), we may say that we
have succeeded in doing what is required, and that all hues in nature,
with their varying shades and brightness, can be equally well repro-
duced. The exponent of colour photography is bound to go to the
spectrum for his information, and this I must do to-night. On the
wall is a diagram of the spectrum in the shape of a curve, which
shows the luminosity of every individual part. If we could abolish
colour from our minds, and merely look upon the spectrum as a
monochromatic band having waves of difierent oscillation frequency,
we should have this same curve, and our eyes would be like a photo-
graphic plate, which knows no colour qua colour. All that the plate
knows is that a certain wave length, having a certain amplitude, will
so afi*ect its sensitive surface that a certain opacity of deposit will
be attained on applying the developer to it. If two or more colours
are mixed, each of the wave lengths will play its own part, and an
opacity will be produced representing the sum of the separate effects.
A little reflection will show that whatever photographs we may obtain
we must use outside coloured light to illuminate them if a coloured
object is to b^ reproduced. V7e have to consider what are the fewest

1898.]

on the Theory of Colour Vision, &c.

803

colours that we can use, for evidently simplicity is a great desidera-
tum, and the number agreed upon must settle the number of separate
photographs required.

This brings us to the question of how we see colour, and how
many sensations of colour we have. I am not going into the de-
batable ground of rival colour-vision theories, but I am going to
adopt for to-night that one which will answer every practical purpose,
and that is the Young theory, in which it is held, and held correctly,
that a red, a green, and a blue sensation are alone needful to produce
the sensation of any other hue by admixture one with another. The
fundamental colour sensations are not necessarily identical with
any particular colour, but as a matter of fact, at all events one of
these sensations is to be found excited singly in the spectrum,
viz. that which is excited by the extreme red. The extreme violet
seems to be a compound of two sensations, one a deep blue and the
other red, so that the pure blue and also the green sensations can
never be singly stimulated in the normal eye. The diagram shows
these sensations as curves representing the stimulations by the
spectrum colours of the seeing apparatus in the retina (Fig. 1). The
scales on each curve are so adapted that when the ordinates of the
sensation curves are equal we get white. To get a yellow, the red
sensations and green sensations are equally stimulated, for there the
curves cut. It will be seen that the purest green sensation is largely
mixed with white, for at one point, where the red and blue curves
cut, the green curve is above them. At that point, then, the red and

m

Fig. 1.

blue, and a certain portion of green, go to form white, and the balance
is green, so here the pure green sensation is diluted with white. At
any other point it is mixed with some other sensation, either red or
blue, and also up to certain points with white. Of course, if we
could get three colours which only stimulated respectively the three
fundamental sensations, we should take three appropriate photo-
graphs of the spectrum and illuminate them with those three colours.

804 Captain Ahney [Feb. 25,

But the amount of white which is in the purest green sensation,
renders it desirable to choose a green which has less white inherent
in it, to prevent the mixture being pale.

In 1861, Clerk Maxwell gave a lecture in this theatre, in which
the method of producing photographs in the colours of nature by
means of illuminating three photographic pictures, and combining
the images together, was foreshadowed, and it is to this, and to his

Fig. 2. — Maxwell's Curves of Colour Sensations.

original work on the mixture of colours, that we must turn. By
means of what he called his colour-box, he could mix any three
colours of the spectrum together, and, for reasons which appeared
adequate at the time, he took a bright red, a bright green, and a
bright blue of the spectrum as best representing the sensations. He
referred all other colours of the spectrum to these, and expressed
them as mixtures of the three. The diagram that he made is given
(Fig. 2). The heights of the different curves he obtained by
measuring the width of the three slits through which any three
chosen colours came, and making such widths the ordinates. The
standard red he chose was a red containing a little green; the
standard green near E is nearly free from white, but a glance at
the diagram (Fig. 1) will show it is mixed with a certain amount of
red ; Maxwell's blue contained a certain quantity of green. This is
merely history, but it may be remarked that where we are dealing
with colours, and not sensations, the colours he chose are probably
nearly the best for the purpose we have in view. I have reduced the
Maxwell curves so as to represent luminosity as well as colour, and
you will see that they all fit into the spectrum curve, and that the
great mass of brightness is due to the green and red. Of blue there
is but very little. These curves should be kept well in your mind.

We need not trouble you much about colour mixtures. I have
an apparatus here which allows us to mix any colours together

Fig. 3.

Wliite. Violt't. Blue. Peacock Cliromiiim Orange. Red.
Green. (ireeii.

Fig 4.

•mm

Eed Imaore.

Green Iniiioe.

Blue hm

1"IG. 5.

Li D

Fig. 6.

Li T)

1898.] on the Theory of Colour Vision, &c. 805

In the small spectrum we can place three slits and make a patch of
white light. By altering the width of one or two of the slits we can
form colours of any hue. [White was here matched, and three other
colours made, and again whiteJ\ Instead of light being diminished
by alteration of the width of the slit, we can cut off varying quantities
from each ray and allow them to impress the retina for different
times, tbe persistence of vision blending the impressions together.
In fact, by an artifice of the kind I have here, which consists of a
long band of paper punctured along the three lines of the slits with
holes of different sizes, and passing the strip in front of the slits, we
can play a regular tune in colour. [^Shoian!]

But we can get these same tunes of colour, though not quite so
pure (i.e. unmixed with white) if we use considerable parts of the
spectrum. The slits are withdrawn, and all those parts of the
spectrum which can come through the holes are mixed together and
the colours are reproduced, but not in quite such purity as before.

There is another method of altering the intensity of the rays, and
that is by placing in front of the slits photographic deposits of
different opacities, and you see that we have, as before, different
colours produced. The diagram (Fig. 3) shows a print of the de-
posits employed. The three rows represent the transparencies of
white, violet, blue, peacock blue, dark green, orange and red, taken
through an orange, a green, and a blue screen respectively. The
three left-hand squares in the transj^arency covered the three slits,
and white was formed on the screen. The next three squares gave a
violet, the next three a blue, and so on. This is the foundation of
colour photography. Having learnt that the colours mixed together
need not be single rays of the spectrum, but may occupy adjacent
parts on each side of the single ray and still produce approximately
the same results, we can go a step further, as it shows that we may
use the light coming through media such as coloured glasses instead
of pure spectrum colours.

An interesting experiment is to imitate the sj)ectrum by means of
a red, a blue and a green glass. A slit is placed in the lantern,
and an image of it thrown on the screen. We have a disc formed of
these three glasses, each being shaded by an appropriate mask, to
imitate the extent of each sensation in the spectrum. This disc
rotates in front of the slit. The varying combinations give a large
range of colour, and we have a tolerable representation of the
spectrum produced.

I think now we are in a position to realise what is required in
order to reproduce by photography the spectrum with all its colours.
TVe must get three photographic negatives, each one of which will
take in only so much of the spectrum as is represented by the colour
sensations as shown in the diagram, and secure that the brilliancy of
the light coming through the transparencies or positives taken from
the negatives at each part shall be represented by the heights of the
curves, the maximum height in the positive being represented in each

Vol. XV. (No. 92.) 3 g

806 Captain Ahney [Feb. 25,

case by bare glass. Bebind tbe " red " pbotograpb we place a red
medium, sucb as red glass, wbicb occupies but a small part of the
spectrum and is equivalent to the red sensation, and behind the
green photograph a green medium, also taking in but a small part of
the spectrum, and behind the blue photograph a blue medium, and if
the luminosity of the mixed light coming through the red, the green,
and the blue when unshaded hy the positives forms white, we shall have
a representation of the spectrum.

Suppose that we were going to reproduce the image of the elec-
tric light carbons by combining three distinct photographs together
backed by proper media, and that we wished to know what each trans-
parency would look like when illuminated with its proper colour, we
can show this in a fairly simple manner. Close in front of the slit of
the spectroscope is a lens of such a focus that a sharp image of the car-
bon points is thrown on the surface of the j^risin. The prism analyses
the colours, and a lens in front of the spectrum collects the coloured rays
again and gives us an image on the screen of the carbon points. Placing
three slits in the spectrum, we alter their width until the image again
appears white at the brightest part. We may substitute three lenses
of equal foci for the single lens, and we have three images side by
side, which, as just seen when combined together, will give the white
image of the crater and the redder image of those parts where
the heat is less intense. We can vary this experiment. If we place
against the prism a small square made up of circular glasses of dif-
ferent colours, we have the image of the glasses on the screen when
the whole spectrum is used. With the slits inserted as before, we
also get white light and the colours of the glasses (Fig. 4). The
three lenses, also placed before the slits, give the separate images
such as we wish to obtain by photographic means.

But how about securing these photographs ? Can we find three
different photographic plates which will be exactly sensitive to the
required parts of the spectrum, excluding all other parts ?

It will be seen that the parts overlap (see Fig. 1). Thus the
green and red curves overlap, as do also the green and the blue.
It may at once be stated that there are no such different kinds of
plates to be found. But if we can find one plate which is sensitive
to the whole spectrum, we can, by using absorbing media, cutoff those
portions which are required. Now the ordinary plate, with short
exposure, is not sensitive much beyond the blue (see No. 4, Fig. 5),
but if we give it a slightly longer exposure it will tJfe found sensitive
to the green and yellow as well, and, with a still further exposure, to
the extreme red ; so that we can use an ordinary plate for the purj)Ose,
as it is sensitive, but in vastly different degrees, to the whole spectrum,
but we have to cut off all the parts we do not want.

In the spectrum of the light transmitted by an orange glass in the
spectrum, we see that the red, yellow and green alone penetrate, and
this is the region of the spectrum that the red sensation curve occu-
pies. A blue-green glass cuts off most of the red and the violet, and

1898.] on the Theory of Colour Vision, &c, 807

this gives the part occupied by the green sensation curve ; and so
with the blue. Evidently, then, by using the orange, blue-green and
blue media for the three photographs of the spectrum, we shall secure
three negatives representing, with some degree of exactness, the sen-
sation curves, though the exposures given to each one will be very
different. The red will require nearly one hundred times more
exposure than the blue, and the green an intermediate exposure.
On the screen we have the negatives obtained, aud also the positives
(Fig. 6). No. 1 was taken through the orange, No. 2 through the
green, and No. 3 through the blue screen. The superposed images
of these three positives, if backed by red, green and blue light, will
give us the spectrum. \Mr. Ives showed the projection on screen.]
The picture is fairly perfect, and exemplifies what can be done with
an oidiuary plate.

What 1 wish to impress upon you is that the screens used for the
taking of the three different negatives must each allow a large part
of the spectrum to pass, whereas the colour screens used to illuminate
the three positives, where the images are superposed, will be more
efficient the smaller the part of the spectrum that is used, for if large
parts are used the colours will be tinged with white. This is a
most important point in three-colour photography.

We have modifications of plates which allow shorter exposures
to be given to the green and the red. Cadett's spectrum plate (see
No. 1, Fig, 5), for instance, can be utilised for giving equal exposures
through a blue, a green and a red medium, when the white light is
first toned down to a pale yellow, which, however, still contains all
the colours of the spectrum.

Then there are others, such as Lumiere's (see Nos. 2 and 3,
Fig. 5), which are sensitive to the green and yellow and red, as well
as to the blue, but which exhibit gaps in sensitiveness in the length
of the spectrum. These plates can be utilised for photographing
colours in nature, though they must fail for photographing the spec-
trum. But to atone for the gaps, the absorbing media used have to
be modified to effect a compromise as it were. Mr. Ives, who is the
inventor of the Photochromoscope, and who is present this evening
to show some of his wonderful results, has kindly lent me a slide
showing the screens with which to take the three negatives with
Lumiere's pan-chromatic plates.

By modifying the screens, any plate which is sensitive to the
yellow and orange may be utilised, even though it is not at all, or
only very feebly, sensitive to tlie red. For be it remembered that the
colours in nature are not pure spectrum colours. A red, for instance,
such as this glass, contains an appreciable amount of yellow in it,
and the yellow will impress the plate sufficiently to answer the
purpose of obtaining the requisite density to represent the red. Of
course, if there were a red of a spectrum simplicity, it would not
impress the plate. Except with the ordinary plate such as I have
used, tbere has to be a series of compromises. Again, it must be

3 G 2

808 Captain Ahney [Feb. 25,

remembered tbat the negatives obtained have to be converted into
positives ; and further, that for effective working all three negatives
must, in ordinary circumstances, be obtained on one plate, and by
one length of exposure. Mr. Ives has worked this out with a wonder-
ful degree of exactitude, and his camera can be examined in the
Library after the lecture to show the manner in which he has
accomplished it. He has aimed at getting a perfectly graduated
negative with each colour screen, and in the positives from them there
are absolutely transparent parts, thus securing the maximum bril-
liancy.

These positives are backed by colour screens chosen to imitate
the three colours used by Clerk Maxwell in his colour mixture equa-
tions.

Now, having explained the principles of the three-colour photo-
graphy, I will get Mr. Ives to throw three or four of his pictures on
the screen, and I have to thunk him for his ready acquiescence in
responding to my request for his help to-night. It is a pleasure
to acknowledge that Mr. Ives has been the pioneer in this colour
photography, working on exact principles, which he has applied to
practical purposes.

In connection with the same subject we have the more recent
process due to Professor Joly, of Dublin. Instead of taking three
negatives and from them three transparencies, he combines the three
in one. To take his negatives he observes the same general principle
as that already enunciated, for he places in contact with his sensitive
plate a screen consisting of a series of orange, green and blue lines
ruled on w^hite glass and touching one another ; each line is ^i^ of an
inch in width. Every third line is a colour screen in orange, the
next line and third from it a green, and the remaining ones blue.
To tone down the excess of blue in daylight, the lens is covered with
a pale yellow screen. The one negative is therefore a mixture of
three colour negatives. A transparency is taken in the usual w^ay,
and by placing in contact with it a screen ruled in red, green and
blue, the red lines occupying the position of the orange line in the
taking screen, the green the green, and the blue the blue, we have a
representation in colour of the original object. [The taking screen,
the viewing screen, and a negative and a positive were shown, as also
a selection of finished pictures taken by Professor Joly.]

Suppose we take one set of Ives' negatives and make duplicate
prints from them in bichromated gelatine, we should get, on develop-
ment, transparent gelatine of different thicknesses. where the light
had most acted the film would be thickest, and where no light had
acted the gelatine would be practically absent, and the intermediate
intensities of light acting would give intermediate thicknesses of
gelatine. We may dye one set of gelatine prints with a transparent
red, a transparent green and a transparent blue, to imitate the viewing
screens, and if these were superposed we should find a very different
result to that obtained by triple projection. What ought to be black

1898.] on the Theory of Colour Vision, dc. 809

would be white, and what ought to be white would be black, and the
colours shown would be complementary. A yellow hy projection we
know is caused by a full mixture of red and green light, but by
superposition the red would cut ofif all the blue-green light, and the
green all the purple light, and the image would be nondescript, and
so with other colours. If we dyed the second set of gelatine
negatives with the complementary colours a very different state of
things would be found. Taking the yellow, for example, which in
the " red " and " green " negatives would be shown by great opacity
and in the blue by total transparency, the part of the print in the
" red " negative would be represented by very feeble sea-green, and
that in the green by very feeble purple, whilst in the blue negative it
would be represented by full yellow. From the first two the only
light penetrating would be the blue, and the only colour reaching
the eye after passing through the third gelatine transparency would
be the yellow, and so for other colours. Hence, for superposed
pictures, either for the lantern or for prints, the complementary
colours to those of the viewing screen should be used. This is the
foundation of most of the three-colour printing processes extant.

We have three such prints in the three colours, lent me by Messrs.
Waterlow & Sons, and here they are superposed to make the final
coloured print. This triple printing can be done either by litho-
graphy or by printing in colour from gelatine films.

I have endeavoured, by a brief sketch, to show you the principles
on which photography in colour has been based — principles which
are truly scientific — and which my friend, Mr. Ives, has adopted in
all his work. The rule-of-thumb man, who works according to his
own sweet wdll, is a man to whom a certain amount of success will
be given, but it is to him who works on the true principles of science
that the highest success must accrue. I have endeavoured to show
you that Young's theory of Colour Vision, though a theory, is yet of
supreme use in this particular branch of industry. I have purposely
omitted to mention many of the glaring mistakes which have been
made by the rule-of-thumb man, both at home and abroad, in regard
to it.

[W. DE W. A.]

810 Mr. W. H. M. Christie [April 22,

WEEKLY EVENING MEETING,

Friday, April 22, 1898.

Sir James Crichton-Browne, M.D. LL.D. F.R.S. Treasurer and
Vice-President, in the Chair.

W. H. M. Christie, Esq. C.B. M.A. F.R.S. Astronomer Eoyal.

The Becent Ecli^pse.

After the failure through bad weather, which was the fate of nearly
all the expeditions in the eclipse of 1896, widely spread though they
were from Norway through Siberia to Japan, it was felt that every
eflfort should be made to occupy as many stations as practicable along
the track of the recent eclipse of 1898, January 22, which, starting
from Equatorial Africa, crossed India and ended in the Chinese Empire.
It was at first hoped that it would have been possible to send one of
the observing parties to Africa, but it was not found practicable to
establish stations in Somali Land, and thus the field was narrowed to
the shadow track through Central India. Practically the choice of
stations was confined to the neighbourhood of the places where the
various railway lines intersect the central line of the shadow track,
and of these the more westerly had the advantage of giving slightly
longer duration of totality. Fortunately the weather chances were
unusually favourable in the recent eclipse, the prospect of clear sky
at that time of year in Central India being so great that Mr. Eliot,
the Meteorological Reporter for India — to whom we are so much
indebted for his collection of the weather statistics — is said to have
put the chances at 25 to 1 in favour of a fine day for the eclipse.

The Joint Eclipse Committee of the Royal and Royal Astro-
■nomical Societies arranged for four parties of observers : —

1. Sir Norman Lockyer, whose main equipment was prismatic
cameras, at Viziadrug.

2. Professor Turner and myself to take large and small scale
photographs of the corona. Karad (south of Poena) was originally
selected, but owing to the outbreak of plague there the Bombay
Government advised its abandonment, and Sahdol (a station further
east and with somewhat shorter duration of totality), on the railway
connecting Katni and Bilaspur, was substituted.

3. Captain Hills and Mr. Newall. Slit spectroscopes and photo-
graphs of corona at Pulgaon.

4. Dr. Copeland to take large scale photographs of the corona
with a lens of 40 feet focus.

Besides these there was a party under the auspices of the British
Astronomical Association at Talni, consisting of Mr. and Mrs.

1898.] on the Becent Eclijpse. 811

Maunder, Mr. Thwaites and Mr. Evershed ; and tlie Viceroy of India
occupied a station in the neigbbourhood of Buxar, near Benares, with
a large party, which included Mr. Pope, of the Indian Survey, who
took photographs of the corona. Mr. Michie Smith, Government
Astronomer at Madras, and a party of observers occupied a station at
Sahdol. There were also three parties of observers at or near Jeur,
to the S.E. of Poena, viz. the American astronomers. Professor Camp-
bell and Mr. Burckhalter, taking large-scale photographs of the
corona; the Japanese astronomers, also taking photographs of the
corona ; and Professor Naegamvala, of the Poona College of Science,
with a large party of observers.

Admirable arrangements were made by the Government of India,
special facilities were accorded by the Indian railway companies,
and valuable assistance was rendered by the Admiralty to Sir Norman
Lockyer, H.M.S. ' Melpomene ' being detailed for his party.

I will now pass on to the consideration of the results obtained in
this eclipse. These may be classified as
I. Photographs of the Corona.
II. Spectroscopic Observations.

III. Polariscopic Observations.

IV. Photographs of Partial Phase for position of the Moon.
V. Miscellaneous.

I. Photographs of the Corona,

A special feature of this eclipse was the number and the variety
of instruments which were utilised to obtain large-scale photographs
of the corona, on a scale of about 4 inches to the sun's diameter.
Professor Campbell, Dr. Copeland and Mr. Michie Smith had each
a telescope 40 feet in length, the form of mounting this long tube
being different in each case. Mr. Michie Smith pointed his tube to
the pole, and reflected the sun's rays into it by a plane mirror turn-
ing about a polar axis — what is known as a polar siderostat. In this
form the image rotates slowly as the mirror turns with the diurnal
movement, and the plate (15 inches square) should therefore be
rotated slowly to get an absolutely fixed image. Mr. Michie Smith
had arranged for this, but did not receive the apparatus in time.
For short exposures of a few seconds, however, the rotation would
hardly be appreciable.

Professor Campbell mounted his tube on a timber framework,
so as to point to the position of the sun at mid-totality, and applied
clockwork to move his plate, which was 17 inches by 14 inches.
Dr. Copeland used a fixed mirror to reflect the rays into his telescope,
which was mounted horizontally, and moved his plate (18 inches
square) by clockwork.

The instrument I used was on a different principle, the large
scale being obtained by applying a concave lens (placed at the proper
point within the focus) to magnify the image formed by an object-

812 Mr. W. H. M. Christie [April 22,

glass of comparatively short focal length, and thus the total length
of the telescope is kept within manageable dimensions — 11 feet in
my case, instead of 40 feet as in the ordinary form. This combina-
tion is in fact an application of the well-known Barlow lens, and
forms what has since become known to photographers as the tele-
photo form. My instrument was the photographic telescope, of
9 inches aperture and 8 feet 6 inches focal length, presented some
years ago to the Greenwich Observatory by Sir Henry Thompson,
and to this was applied a tele-photo concave magnifier of 3 inches
diameter giving a solar image 4 inches in diameter, with a field of
view of 10 inches diameter (2 J diameters of the sun).

The same so-called tele-photo form was also used for two smaller
telescopes of 4 inches aperture which gave a solar image 1 J inches in
diameter, each of these being combined with another photographic
telescope of 4 inches aperture and 62 inches focus (known as the
Abney lens) in a double tube. Thus each " double tube " gave two
photographs of the corona, large and small scale, the former to show
detail and the latter to give as great extension as possible. These
" double tubes" wore first used in the eclipse of 1893. In the recent
eclipse they were efiectively employed by Professor Turner at Sahdol,
and by Captain Lenox Conyngham, K,E., under Captain Hills' direc-
tion, at Pulgaon.

Another important feature in the instrumental equij^ment was the
coelostat, a form of mounting a mirror devised by M. G. Lippmann
in 1895, and successfully used in the recent eclipse at three stations
(Sahdol, Pulgaon and Viziadrug) ; the observers being indebted to
Dr. Common for designing the instruments, supervising their con-
struction and, most important of all, supplying the large plane mirrors
(16 inches in diameter).

Another new departure of much interest was Professor Burck-
halter's device for giving to each part of the corona the exact
exposure best suited to its brightness. The brightness of the inner
parts near the sun's limb is so overpowering, as contrasted with the
faintness of the outer streamers, that widely ditFerent exposures are
required to bring out their respective details, and thus it is necessary
to take a series of photographs, the combination of which should
represent the whole phenomenon.

Professor Burckhalter arranges to get the whole on one plate by
giving exposures rapidly increasing from the sun's limb to the edge
of the field, this being effected by means of a slit of peculiar form in
a metal screen which rotates rapidly in front of the photographic
plate, and thus gives intermittent exjjosures of duration depending on
the width of the slit, which increases rapidly from the sun's limb
outwards.

Another interesting instrument was that used by Mr. Thwaites at
Talni with a triple object-glass, 4i inches in diameter, of Cooke's
new form adapted both for visual observation and for photography.

Valuable series of photographs of the corona were obtained with

1898.] on the Becent Eclipse. 813

all these instruments, the exposures being so arranged that each series
of photographs would give a complete representation of the corona,
showing the details in the different parts.

A small-scale photograph of the corona, taken by Mrs. Maunder
with a lens of 1^ inch aperture and 9 inches focus on a Sandell
triple-coated plate, is remarkable for the great extension of the
corona which it shows, one ray in particular being traceable to a
distance of nearly 3° from the sun.

II. Spectroscopic Observations.

These were made with two classes of instruments :
a. Slit Spectroscopes.
h. Prismatic Cameras.

a. Slit Spectroscopes. — Captain Hills, R.E , using two spectro-
scopes with two flint prisms and four quartz prisms respectively, fed
by a 12-inch heliostat, in combination with two telescopes of 4J-inch
and 5-inch aperture respectively, obtained fine photographs of the
coronal spectrum and of the flash spectrum at the beginning and end
of totality. These latter show clearly the progressive changes from
the dark line spectrum of the sun to the bright line spectrum of the
chromosphere as the moon covered the sun's disc.

Mr. Newall with a 4-prism spectroscope attempted to determine
the relative motion of the corona on opposite sides of the sun in the
line of sight, by the displacement of the coronal lines in the spectrum ;
but unfortunately his attempt to determine the rotation of the corona
failed through the faintness of the spectrum at the region photo-
graphed, only 8' from the sun's limb. He, however, succeeded in
obtaining a fine photograph of tho spectrum of the flash at the
end of totality. He also observed the distribution of coronium round
the sun's limb with a diffraction grating in front of an object-glass of
3J inches aperture and 29 inches focus. With this instrument he
noted seven bright patches of coronium, three being traced to a dis-
tance of 12' from the sun's limb. Two of these coincided roughly
with coronal streamers in the north-east and south-west.

b. Prismatic Cameras. — Sir Norman Lockyer's party at Viziadrug
made use of two prismatic cameras, i.e. photographic telescopes, with
one or more large prisms placed in front of the object-glass. One of
these had an object-glass of 6 inches aj^erture with two large prisms
in front of it, the other was larger, having an object-glass of 9 inches
aperture, but with only one prism, so that its dispersion was only
about half of that given by the other.

With these instruments valuable series of photographs were
obtained at the beginning and end of totality, showing the spectrum
of the chromosphere, and during totality for the coronal spectrum. In
each case rings represented the various lines of the spectrum, giving
the images of the chromosphere or corona surrounding the eclipsed
sun as formed by light of the various wave-lengths emitted by it.

814 Mr. W. E. M. Christie on the Becent Eclipse. [April 22,

Mr. Evershed at Talni also obtained fine photographs of the spec-
trum of the chromosphere and corona with a smaller prismatic
camera.

III. Polariscopic Observations.

Professor Turner at Sahdol obtained photographs showing radial
polarisation in the coronal streamers, his object being to determine
how much of the light of the corona is polarised radially, and conse-
quently due to reflected sunlight.

Mr. Newall made eye observations which indicated strong polari-
sation of the atmosphere at all points within 30° of the sun, the plane
of polarisation being not vertical.

IV.

Photographs of the partial phase for determination of the position
of the moon were taken by me at Sahdol, the longitude and local time
being accurately determined by Major Burrard, E.E., and Lieut.
Crosthwaite, R.E., of the Indian Survey Department.

V. Miscellaneous.

A number of drawings of the corona were made by observers at
the various stations occupied, but their value would have been much
greater if the observers had worked with a stump to represent the
gradations of light in the corona, instead of attempting to draw with
a pencil an outline of the corona, which has essentially no defined
boundary.

[W. H. M. C]

1898.] Liquid Air as an Analytic Agent. 815

WEEKLY EVENING MEETING,

Friday, April 1, 1898.

Sir Edward Frankland, K.C.B. D.C.L. LL.D. F.R.S. Vice-
President, in the Chair.

Professor Dewar, M.A. LL.D. F.E.S. M.BJ.

Liquid Air as an Analytic Agent.

The increasing importance of low-temperature research is shown
by the gradual development of the applications of liquid air for
scientific and other purposes. The much larger apparatus now used
in the production of the liquid enables experiments to be made on a
more imposing scale.

Liquid air poured from a tin can, filled by being dipped into a
5-gallon jar filled with the liquid, into a large silver basin heated to red-
ness, remained apparently as quiescent at this high temperature as in
cooler vessels, and maintained a spheroidal condition, just like other
liquids. The temperature of the liquid air was about —190° C, or
83^ absolute, while the vessel in which it was placed had a temperature
of 800° C, or 1073° Ab. In other words, between the wall of the
silver vessel and the liquid air there was a difference of temperature
of 1000° C, 12 times the absolute temperature of the liquid.

Liquid air can be of great service in the qualitative separation
of mixtures of gases. With the object of ascertaining the propor-
tion of any gas in air that is not condensable at about —210° C. under
atmospheric pressure, or is not soluble in liquid air under the same
conditions, a series of experiments was made with the following
apparatus.

A cylindrical bulb of a capacity of 101 c.c, marked B in figure,
had a capillary tube sealed into it terminating in a three-way stop-
cock, as shown at E. The parts marked C and D consist of soda-lime
and sulphuric acid tubes for removing carbonic acid and water. The
stand marked G holds the large vacuum test-tube into which B is
inserted, and which contains liquid air maintained under continuous
exhaustion. As this low temperature had to be kept steady from
one to two hours, while at the same time the bulb B had to be com-
pletely covered with liquid air, it was necessary to arrange some means
of keeping up the liquid air supply without disturbing the apparatus.
The plan adopted is shown at H, which is a valve arrangement which
can be so regulated as to suck liquid air from the large vacuum
vessel A, and discharge it continuously along a pipe into the vacuum
test-tube G, the latter being kept under good exhaustion. In work-
ing the apparatus, the tube I is connected to a gasometer containing
10 cubic feet of air, so that the volume of air condensed in each

816

Professor Dewar

[April 1,

experiment may be observed. This was generally from 2 J to 3 cubic
feet. If there is a very small proportion of some substance not
liquefiable or soluble in liquid air, then we should expect the vessel
B would not fill up completely into the capillary tube. This is,
however, exactly what does take place. After 40 minutes' cooling,

Fig. 1.

the vessel B and the cool part of the tube were filled with liquid.
In this experiment some 80 litres of air were condensed, and any
accumulated uncondensed matter must have been concentrated in the
upper part of the capillary tube, which had a volume of 0 * 5 c.c.
Under the conditions, therefore, the material looked for must be
less than 1 part by volume in 180,000 of air.*

* These experiments, alono; with the succeeding ones on Bath Gas, were
all described in a Paper entitled, ' Liquefaction of Air and the Detection of
Impurities,' given at the Chemical Society on 4th November, 1807.

1898.] on Liquid Air as an Analytic Agent 817

To test the working with an unoonden sable gas added to air, a
volume of 10 cubic feet was taken in the gasholder, and to that
500 c.c. of hydrogen were added. This is in the proportion of less
than 1 in 500. Even after two hours' cooling, the tube B could only
be filled four-fifths. In order to prove that the gas accumulated in
the upper part of B was hydrogen, the three-way stopcock at E was
turned, and the temperature allowed to rise, so that tlie gas was
expelled from the evaporation of the liquid air and collected over
mercury as shown at F. The gas thus collected was easily com-
bustible and consisted chiefly of hydrogen. The amount of hydrogen
was then reduced to 1 part in 1000 of air, and it was found that
after one-and-a-quarter hours' cooling, the bulb B had filled to
within a half c.c. of the capillary tube. A new sample of air con-
taining 1 part of hydrogen in 10,000 of air, filled the bulb B com-
pletely as if it were ordinary air.

It appears from these experiments that 1 part of hydrogen in
1000 of air is just detectable in the form of an uncondensable residue.
As the 80 litres of air coiidens -^d contained some 80 c.c. of hydrogen,
it appears that 100 c.c. of liquid air at from —200° to —210° C. had
dissolved nearly all this gas ; in fact, that 20 c.c. of hydrogen at
the low temperature is dissolved in 100 c.c. of liquid air, and can
only be detected by examining the first sample of gas boiled off or
extracted by lowering the pressure on the liquid. In the paper on
' The Liquefaction of Air and Research at Low Temperatures,' * it
was shown that if hydrogen containing a small percentage of oxygen
were employed for the purpose of getting a hydrogen jet, the liquid
collected from it was oxygen, containing, however, so much hydrogen
dissolved in it that the gas coming off for a time was explosive.

Coal gas, which is a mixture of hydrogen, marsh gas, carbonic oxide,
and various illuminating gases and impurities, after passing through
a coil of pipe surrounded with solid carbonic acid for the purpose of
condensing the vapours of benzol, naphthalene, &C.5 when supplied to a
tube similar to B, surrounded by boiling liquid air, gave a liquid and
gaseous portion at the lowest tem[ erature. It was possible to con-
dense in this way all the constituents of coal gas, and to separate
them after liquefaction by fractional distillation, except carbonic
oxide and hydrogen.

Ultimately, however, the carbonic oxide would be condensed, and
hydrogen be left alone in the gaseous state. Similarly, any gas less
easily condensed than air could be separated from a mixture of the
same with air. Hydrogen present in air to the extent of one in a
thousand is just detectable, but smaller quantities escape direct obser-
vation owing to solution in the liquid. In order to press this inquiry
a little further, some natural gas known to contain a different con-
stituent, like helium, suggested itself as being worthy of trial. Lord
Rayleigh's analysis of the gas from the King's Well, at Bath, gave

* Proc, 1895, vol. xi. p. 221.

818 Professor Dewar [April 1

1*2 part of helium per 1000 volumes, so that it seemed admirably-
adapted for such experiments. By the kind permission of the
Corporation of Bath, an abundant supply of this Gas was obtained
for experimental purposes.

In a paper read before the Eoyal Society on December 19, 1833,*
by Dr. Daubeny, Professor of Chemistry at Oxford University, on the
' Quantity and Quality of the Thermal Springs of the King's Well in
the City of Bath,' there are some interesting details. Dr. Daubeny's
experiments extended over a month, and he estimated the volume
of gas given off as from 80 to 530 cubic inches per minute
(average 264). The temperature of the water of the King's Well
was 115° Fahr., and the amount of water per minute was equal to
126 gallons. The average volume of gas was 240 cubic inches per
minute. The gas was collected from an area of 20 feet in the centre
of the bath ; the maximum amount of gas obtained was 300 cubic
inches, while the minimum quantity was 194 cubic inches per minute.
Calculated at the rate of evolution of 250 cubic feet per day for
50*^0 years, then the whole gas given off amounts to 456 million cubic
feet.

Thirty-two years after Daubeny's experiment Professor Williamson
made a more elaborate examination of the Gases of the King's Well.
In B.A. Reports, 1865, he gives the following as the volume com-
position of the gas : —

Carbonic Acid. Oxyofeii. Marsh Gas. Nitrogen,
2-948 0-54 0-18 9G-33

3-056 0-617 0-216 96-11

Williamson used a funnel 8 ft. 9 in. in diameter to collect the gas,
and obtained a quantity equal to a rate of 112 cubic feet per day.
This is only about half the amount Daubeny collected, and may be
exj^lained by the great alterations made in the bath itself between
the dates of the observations.

In passing, it is interesting to note the general character of the
saline constituents of the spring, as the most probable hypothesis is
that the argon and helium come from the rocks traversed by tlie
water. The following analysis was made by Dr. Attiield.

Grs. per Gallon.

Carbonate of calcium 7-8402

Sulphate ot calcium 94-1080

Nitrate of calcium •56'i3

Carbonate of niagnesiura * 561 1

Chloride of magnesium 15-2433

Chloride of sodium 15-1555

Sulphate of sodium 23-1400

Sulphate of potas>ium 6-7020

Nitrate of potassium 1-0540

Carbonate of iron 1-2173

Silica 2-7061

168-2898

■^ iioyal Soe. Proc., vol. iii. p, 254.

1898.] on Liquid Air as an Analytic Agent. 819

Ramsay, the geologist, estimated the mineral ingredients obtained
from this source in one year would equal a square column 9 feet in
diameter and 140 feet high. Roscoe detected by spectroscopic ex-
amination the presence of lithium, strontium and copper. The sample
of Bath gas examined by Rayleigh contained scarcely any oxygen and
but little carbonic acid. The weight in a given globe of the N from
the Bath gas (2 • 30522) is about half-way between that of chemical
nitrogen (2 '299) and "atmospheric" nitrogen (2*3101), suggesting
that the proportion of argon is less than in air, instead of greater, as
had been expected. Later experiments by Rayleigh proved that
this nitrogen contained helium as well as argon.

The sample of gas from the Bath Spring was treated exactly in
the same way as the hydrogen mixtures before referred to. During
liquefaction there was a marked difference in the appearance of the
liquefied gases, for while the hydrogen and air mixtures on condensa-
tion gave clear transparent liquids, the product from the Bath gas
was turbid, and a precipitate gradually formed which by transmitted
light looked yellowish-brown. The yellowish-brown precipitate is a
hydro-carbon, probably of the petroleum series, having a marked
aromatic smell, and is liquid at the ordinary temperatures. It was
probably this gas which Professor Williamson gave as marsh gas in his
analysis. Further research will be made on this substance. Another
peculiarity of the liquid nitrogen obtained from Bath gas is that, on
examining it with a spectroscope, even through a thickness of two
inches of liquid, no trace of the characteristic oxygen absorption spec-
trum could be obtained. In all other attempts to make nitrogen for
liquefaction on the large scale, oxygen could always be detected in
the liquid by means of its absorption spectrum. Another phenomenon
was that the gas from the King's Well could not be entirely condensed
by refrigeration with liquid air boiling in vacuo. After the cooling
had continued for some time, the gas ceased to flow into the condens-
ing vessel, and the upper part of the vessel was occupied by a gas
that would not undergo liquefaction at the temperature together with
substantially liquid nitrogen saturated with the said gas.

About 70 litres of the Bath gas were condensed, certainly the
largest quantity of this gas ever subjected to chemical examination.
This was boiled off, and a^ by accident too much nitrogen had vola-
tilised along with the gas, oxygen was added, and the mixture sparked
over alkali, to get rid of the excess of nitrogen. The samjile of gas
directly collected from the liquid nitrogen contained about 50 per
cent, of helium. During the sparking the helium lines were well
marked (along with others, the origin of which must be settled later),
and a vacuum tube filled with the product of the sparking gave a
splendid spectrum of the gas. The recorded unknown lines in the
Bath helium were subsequently detected along with helium in the
more volatile portion of liquid air.* Eight months after my paper
to the Chemical Society, and some two months after this address was

♦ See 'Nature,' vol. Iviii. p. 570, Letter of Sir William Crookes, Oct. 11, 1898.

820

Professor Deimr

[April 1,

Fig. 2.

A, glass vacuuia vessel, containing liquid air. B, tube of argon. C, tube of
liquid chlorine. D, tube of metallic sodium. E, Routgen X-ray bulb, F, photo-
gr.tpliic plate behind sheet aluminium.

1898.] on Liquid Air as an Analytic Agent. 821

delivered, the same material was found by Professors Kamsay and
Travers to exist in argon, and has been recognised and named by
them Neon, a new element.

It is, therefore, possible to separate helium from other gases by
liquefaction when it is only present to the extent of one part in one
thousand. From this it would appear that heliima is less soluble in
liquid nitrogen than hydrogen in liquid air, and is of greater volatility
than the constituents of the other gases which were condensed. If the
sample of the uncondensed gas from the first liquefaction of the Bath
gas were again treated in the same way, a much more concentrated
specimen of helium could be obtained. Provided helium were wanted
on a large scale, then a liquid air apparatus, similar to that in use at
the Royal Institution, transported to Bath, and worked with the gas
from the King's Well, could be made to yield a good supply, as the
gas contains 1 • 2 parts in 1000.

Argon, which is present in the proportion of 1*4 per cent., con-
denses with the nitrogen; but if the liquid be allowed to slowly
boil away, a residuum may be obtained containing about 7 per cent,
of argon. Argon, when frozen, solidifies to a perfectly clear glass.

Absorption of Rontgen Radiation at Low Temperature by
Different Bodies.

The transparency of bodies to the Rontgen radiation is an inter-
esting study, although we are not in a position to draw definite con-
clusions from the results. As a general fact we know the opacity
of elements in the solid state increases with the atomic weight.

In the experiments small tubes of the same bore were filled re-
spectively with liquid argon and chlorine, potassium, phosphorus,
aluminium, silicon and sulphur, and exposed at the temperature of
liquid air (in order to keep the argon and chlorine solid) in front
of a photographic plate shielded with a sheet of aluminium to an
X-ray bulb (see Fig. 2). The order of increasing opacity of the
shadow of each substance was observed, and the sequence in the list
given above represents the results. A tube containing silicon was
a little more transparent than the potassium or chlorine. Sodium
and liquid oxygen and air, nitrous and nitric oxides proved much
more transparent than chlorine. Tubes of potassium, argon and
liquid chlorine presented no very marked difference of density on
the photographic plates.

From these experiments it would appear that argon is relatively
more opaque to the X-rays than either oxygen, nitrogen, or sodium,
and that it is on a level with potassium, chlorine, phosphorus, alu-
minium and sulphur. This may be regarded as supporting the view
that the atomic weight of argon is twice its density relative to
hydrogen.

Thermal Transparency at Low Temperatures.

Pictet, after an elaborate investigation, concluded that below a
certain temperature all substances had practically the same thermal
Vol. XV. (No. 92.) 3 h

822 Professor Dewar [April 1,

transparency, and that a non-conducting body became inefifective at
low temperatures in shielding a vessel from the influx of heat.
Experiments, about to be detailed, however, prove that such is not
the case, the transference of heat observed by Pictet appearing to
be due not so much to the materials themselves as to the air con-
tained in their interstices. Good exhaustion in the ordinary vacuum
vessels used in low temperature work reduces the influx of heat to
one-fifth of what is conveyed when the annular space of such double-
walled vessels is filled with air. If the interior walls are silvered,
or excess of mercury is allowed to remain, the influx of heat is
diminished to one-sixth of the amount entering without the metallic
coating. The total efi'ect due to the high vacuum and silvering is
to reduce the ingoing heat to one-thirtieth of the original amount,
i.e. roughly, to 3 J per cent.

By filling the annular space between the walls of several similar
vacuum vessels with various substances, and exhausting them all
to the same low pressure, large differences in the thermal isolation
were observed. The rate of evaporation of equal volumes of liquid
air contained in the respective vessels measures the rate of influx of
heat. Moreover, it appears that what might bo called under the
circumstances the thermal transparency of some materials diminished
at very low temperatures instead of increasing, as had been asserted.
Thus, of two vacuum tubes (one simply exhausted, and the other having
powdered carbon in the vacuum space), the latter, at low temperature,
was the most efficient preserver of liquid air, showing that tbe carbon
diminished the radiation and gas convection. But when the vacuum
was destroyed and air admitted into the space, the liquid air in the
carbon tube boiled oft' much more vigorously than that in the simple
tube, indicating that at ordinary temperatures carbon allowed more
heat to pass than did air.

In conducting these experiments, generally sets of three double-
walled glass tubes, as nearly identical in size and shape as possible,
were mounted on a common stem, and two out of the three filled with
different kinds of powders, while the third is left empty as a standard
for comparison (Fig. 3). In this way each set had the same vacuum,
and as intercommunication between the tubes after sealing off from
the pump was left free, any deterioration in the vacuum on keeping
affected all three vacuum tubes to the same extent.

The preparation of such tubes entails enormous labour, because
it takes days of exhaustion with a mercurial pump to extract the
occluded gases, even at as high a temperature as the glass would
stand. Before beginning the experiment, the vacuum tubes of each
triple set were filled with liquid air, and allowed to stand half an
hour in order to get the heat conduction in the porous mass into a
steady state. The tubes after this treatment were filled to the same
height, and the relative times required to distil off the same volume
of liquid air from each observed — the outer surface of the vacuum
tubes being maintained at a steady temperature by immersion in a large
vessel of water. Neither the tubes nor the shape of the vacuum space

1898.]

on Liquid Air as an Analytic Agent.

823

in each were absolutely identical, so that the results are simply com-
parative. The general ratio of heat propagation found for two
substances when different sets of double-walled tubes of about the
same form and proportion were compared, remained substantially

J:''iG. 3. — Three tubed blowu on to oae ^tem, so that the exhaustion in each
would be identical.

A, filled with lampblack between the inner and outer tubes. B, annular
space left empty. C, filled with silica between the tubes. A', B', C, the same
tubes in section.

constant when a high vacuum was reached. A confirmation of the
results was generally made by noting the time required to evaporate
the whole of the air from each tube. The annular vacuum space
had generally a thickness of 4 to 5 mm., and was in each case com-
pletely filled up with the solid. In reality, however, the absolute

3 H 2

824

Professor Dewar

[April 1,

fraction of the space filled by the solid did not exceed one-half.
The effect of any considerable inequality in the thickness of the non-
conducting powders was ascertained by comparing two vacuum tubes,
one having double the thickness of vacuum space of the other, and
each then filled with precipitated silica. Taking the unfilled vacuum
tube as the unit for comparison as described above, then the single
thickness of silica increased the insulation to 6 and the double
thickness to 8. The following table contains the results of a number
of experiments with triple sets of double-walled tubes filled with
different substances, when exhausted and unexhausted. The results are
expressed in the relative times required to volatilise the same small
volume of liquid air from each tube. This is most readily done,
after filling each tube with the same volume of liquid air, by noting
the time required to fill a given vessel standing over the pneumatic
trough with the gaseous air distilling off.

In each triple set the unit taken for comparison is the time value
of the free vacuum spaced tube.

Empty Tube 1 I'O

Charcoal 5 0'7

Magnesia 2 0*6

Vacuum. Air.

Empty Tube 1 1-0

Lampblack 5 07

Silica 4 0-7

Vacuum.

Empty Tube 1

Graphite 1"3

Alumiua 3' 3

Vacuum.

Empty Tube 1

Lampblack 4

Lycopodium 2*5

Empty Tube
Calcium carbonate
„ fluoride

Vacuum.
. 1
. 2-5
. 1-25

Empty Tube . .
Barium carbonate
Calcium phosphate

Vacuum.

Empty Tube 1

Phosphorus (amorphous) . . 1
Mercuric iodide 1*5

Empty Tube
Lead oxide
Bismuth oxide

Vacuum.
. 1
. 1-3

. 2-7

Vacuum.
. 1
. 2
. 6

From these experiments it will be seen that silica, charcoal,
lampblack and oxide of bismuth all increase the insulation to 4, 5,
and 6 times that of the empty vacuum space. In tubes generally
which did not reach such a high vacuum the relative insulating
effect of these powders could be raised as much as 1 to 8 or 1 to 10.
In this case the influx of heat per unit of time in the vacuum tube
which did not contain any finely divided powder was necessarily
much greater. As the chief communication of heat is by molecular
bombardment the fine powders must shorten the free path of the
gaseous molecules, and the slow conduction of heat through the
porous mass must make the conveyance of heat energy more difficult
than when the gas molecules could directly impinge upon the outer

1898.1

on Liquid Air as an Analytic Agent.

826^

glass surface maintained at a higher temperature. To separate the
true conduction from the radiation and the gas motion would require
far more elaborate experiments, but these are sufficient to prove that
the presence of certain finely divided solids in the high vacuum space

Fig. 4. — Three tubes blovvu un to one stem, similar to Fig. 3.

A, vacuum space having three turns of gold paper, gold outside. B, vacuum
space having some pieces of gold leaf put in so as to make contact between walls
of vacuum tube. C, vacuum space empty. A', B', C, the same tubes in section.

of the vessels used in low temperature research improves the heat
insulatiou, wh'le in the presence of air the same bodies facilitate the
transference of heat. This is the explanation of Pictet's apparently
extraordinary results.

In no case was the diminution of the influx of heat, in the case of

826

Professor Dewar

[April 1,

the use of finely divided solids, ever so effective as a high vacuum,
in an empty tube, the glass surfaces being silvered. This is seen by
reference to results recorded in Tables Nos. 1, 2 and 3, where the
insulation is increased in the proportion of more than 1 to 7, which
is decidedly better than anything reached by the use of powders.

It will be noted that the use of silica and charcoal to fill up the
annular spaces between the walls of these silver-coated vacuum
vessels has produced very different results from those recorded in
the former experiments with plane glass surfaces. Instead of the
heat insulation being increased from 4 to 5 times by the use of such
powders, it is now only very slightly benefited. This suggests that
the finely divided solid affects chiefly the combined radiation auJ
conduction factors.

A further set of experiments was made with similar vacuum tubes,
replacing the powders by metallic and other septa (Fig. 4). Various
papers coated with metallic powders in imitation of gold and silver
which are in common use, were compared with black paper and a com-
parison made between the use of sheet lead and aluminium, all under
similar conditions.

The following tables express the comparative results of the differ-
ent experiments.

(1)
Vacuum space empty, not sil-
vered 1

8ame space unexhausted .. .. 0*25
Vacuum sf^ace empty, silvered
on both surfaces 7 ' 4

(2)

Vacuum space empty, silvered on

inside surfaces 1

Silica in silvered vacuum space 1 • 1

Empty silvered vacuum 1

Charcoalin silvered vacuum 1*25

Vacuum space unsilvered 1

„ silvered inside 5

„ in annular space with glass test-tube silvered .. G

(4)

Vacuum space empty 1

Tliree turns silver paper, bright

surface inside 4

Three turns silver paper, bright

surtace outside 4

(6)
Vacuum space empty
Three turns gold paper, gold out-

side

Some pieces of gold leaf, put in
so as to make contact between
walls of vacuum tube

1

4

0-3

(5)

Vacuum space empty 1

Three turns b^ack paper, black

outside 3

Three turns black paper, black

inside 3

(7)

Vacuum space empty 1

Three turns, not touching, of sheet

lead 4

Tluee turns n(*t touching, of sheet

aluminium 4

The experiments show that liquid air can be conveniently used
to study many important problems of heat transmission.

1898.]

on Liquid Air as an Analytic Agent.

827

Photographic Action at the Temperature of Liquid Air.

In a former lecture on Phosphorescence and Photographic Action,
it was shown that photographic action was reduced by 80 per cent,
at the temperature of — 182° C. It was further proved that a sensi-
tive film was still comparatively active at the temperature of — 210° C.
Experiments in this direction have been continued at different times.

In these new experiments the source of light was respectively a 16
candle-power lamp, a magnesium and cadmium spark discharge, and
a Eontgen bulb. Small dark slides were prepared having a circular
hole. One was placed in liquid air, and another simultaneously exposed
for the same time at the ordinary temperature (Fig. 7). They were
developed together, and the density of the image observed (Fig. 5).

• e

Fig. 5.

1, photographic film exposed at ordinary temperature. 2, photographic film
cooled in liquid air during exposure.

Both were exposed for the same length of time, and both were developed
together.

2.

Fig. 6. — Ultra-violet spectrum of spark discharge.

1, on film at ordinary temperature. 2, on film cooled in liquid air.
Both exposed for the same length of time and then developed together.

Distance op Plates feom Source op Light giving the
Photographic Intensity.

SAME

Source of Light.

Cooled Plate.

Uncooled Plate.

Ratio of

Intensities at

Balance.

16 candle-power lamp

Ultra-violet spark magnesium andl
cadmium ., ../

Kontgen bulb

in.
20

22i

10

in.
50

90

24f

Ito 6
ltol6
1 to 6

828

Professor Dewar

[April 1,

Fig. 7.

A, vacuum cup with liquid air, into which is placed a photographic film in £
small metallic slide having a hole in the centre. C, a metallic slide, holding a
photographic film, which is exposed at ordinary temperature.

^ Both of these are exposed to the light from a 16 candle-power lamp D, con-
tamed in a box. The light is diminished or increased by the diaphragm at E.

1898.] on Liquid Air as an Analytic Agent. 829

Further trials were made by bringing the cooled plate nearer to the
source of light until finally a position was found where the very
feeble photographic impression that appeared on both plates had the
same density. In this position the relative distances of the plates
from the source of light were measured. This mode of conducting
the photographic comparison of the hot and cold plates gets over the
difficulty of variation in the intensity of the source of light. From
these experiments it would appear that when cooled to the tempera-
ture of liquid air both the incandescent lamp and the Eontgen radia-
tion were reduced to 17 per cent, of their photographic action at the
ordinary temperature ; whereas the ultra-violet radiation was reduced
to about 6 per cent. This marked increase in the inertia of the photo-
graphic plate at low temperatures for the short wave-lengths cannot
be explained by the absorption of liquid air, for such radiation as
this is small for a thickness of 10 to 20 mm. of the liquid. It is
possible that the ultra-violet radiation is dissipated by the photo-
graphic film at low temperatures to a greater extent than with ordi-
nary light, through absorption and subsequent emission as a phos-
phorescent glow. It would seem probable that if the plate could be
developed at these low temperatures no action would be apparent,
and that it is during the heating up after the low temperature ex-
posure that the photographic action on the film takes place through
an internal phosphorescence. This possibility must make us cau-
tious in drawing inferences as to possible chemical action at low
temperatures.

A more elaborate study of photographic and phosphorescent effects
at low temperatures would add much to our knowledge of the
chemical and physical actions of light.

Vol. XV. (No. 02.) 3 i

INDEX TO VOLUME XV.

Abel, Sir Frederick, Donations, 309,

603, 789.
Abney, Captain, The Theory of Colour

Vision, 802.
Address to H.M. The Queen, 502 ;

reply, 511.

to Lord Kelvin, 235 ; reply, 283.

Ail-, Liquid, 133, 557.

Solid, 136.

Amazon River, Cable Laying on, 219.
Annual Meeting (1896) 175, (1897) 433,

(1898) 722.
Antivenene, 107.
Argon, 1.

Armistead, J. J., Fish Culture, 39.
Assyria, Metals used in, 609
Audition, Limits of, 417.

Bacterial Condition of Water, 64.
Barry, J. Wolfe, Donation, 309.
Beutinck, Lord William, 665.
Bidwell, S., Some Curiosities of Vision,

354.
Binnie, A. R., The Tunnel under the

Thames at Blackwall, 81.
Birmingham, Bringing of Water to,

from Wales, 679.
Birrell, A., John Wesley : Some Aspects

of the Eighteenth Century, 233.
Blackwall Tunnel, 81.
Bose, J. C, Polarisation of the Electric

Ray, 293.
Bramwell, Sir Frederick, Donation,

783.
Brunner, Sir John, Donation, 789.
Buds and Stipules, 565,

Cable Laying on the Amazon River,
217.

Canterbury Cathedral, 698.

The Dean of, Canterbury Cathe-
dral, 698.

Carrington, John B., Donation, 793.

Cathode and Rontgen Radiations, 580.

Rays, 419.

Centenary of the Royal Institution, to
be celebrated in 1899, 603.

Chemical Elements in relation to Heat,
735.

Christie, W. H. M., The Recent

Eclipse, 810
Chronographs, 176.
Clarke, Sir Andrew, Sir Stamford

Raffles and the Malay States, 754.
Collier, Hon. John, Portrait Painting,

36.
Colour Photography, 151, 802.

Vision, Theory of, 802.

Compressed Air in Tunnelling, 87, 93.
Conder, C. R., Palestine Exploration,

346.
Contact Electricity of Metals, 521.
Crookes's Researches on Electric

Shadows, 191.
Crookes, W., Diamonds, 477.
Crystals, Living, 723.

Dew^ar, J., Donations, 283, 603, 783.
Liquid Air as an Analytic Agent,

815.
New Researches on Liquid Air,

133.

Properties of Liquid Oxygen, 555.

Re-elected Fullerian Professor of

Chemistry, 147.
Diamonds, 477.

Dickson, C. Scott, Donation, 793.
Dixon, Harold, Explosion Flames, 451.

Early Man in Scotland, 391.

Earthquakes, 326.

Eclipse, The Recent, 810.

Egvpt, Development of the Tomb in,

769.

Metals used in, 608.

Electric Ray, Polarisation of, 293.
Research at Low Temperatures,

239.

Shadows and Luminescence, 191.

Electro-Magnetic Radiation, 293.
Ellis, A. J., Collection of Tuning

Forks presented, 511.
Ewing, J. A., Hysteresis, 227.
Explosion Flames, 451.

Faraday's Discoveries in the Polarisa-
tion of Light, 706.
Farrer, Sir W. J., Donation, 413.

INDEX.

831

Fish Culture, 39.

Flames, Source of Light, 366.

Fleming, J. A., Electric and Magnetic
Researcli at Low Temperatures, 239.

Fluorine, 145, 452.

Frankland, E., Water Supply of Lon-
don, 53.

Fraser, T. E., Immunisation against
Serpents' Venom, &c., 107.

Garnett, Thomas, Portrait Presented,
799.

Gladstone, J. H., The Metals Used by
the Great Nations of Antiquity, 608.

Gray, Andrew, Magneto-Optic Rota-
tion, 703.

Greece, Metals Used in, 617.

Grove, Sir William, Bust of, Presented,
289.

Gun Ballistics, 176.

Handwriting, 375.

Hawkins, A. H., Romance, 438.

Hawksley, G., Donation, 783.

Heat, Chemical Elements in Relation

to, 735.
Helium, 8.
Heycock, C. T., Metallic Alloys and

the Theory of Solution, 409.
History, The Picturesque in, 313.
Humour, 96.

Hydrogen, Liquefaction of, 142.
Hysteresis, 227.

Instinct and Intelligence in Animals,
567.

Kelvin, Lord, Address to, on the occa-
sion of the Jubilee of his Professor-
ship in University of Glasgow, 235 ;
reply, 283.

Contact Electricity of Metals, 521

Lee, Sidney, National Biography, 27.

Lenard's Researches on Electric
Shadows, 202, 430.

Leonard, H., Donation, 661.

Lilly, W. S., Theory of the Ludicrous,
95.

Lippmann,G., Colour Photography,151.

Liquefying Apparatus, 134.

Liquid Air, 133.

as an Analytic Agent, 815.

Oxygen, Properties of, 555.

Living Crystals, 723.

London, Lord Bishop of, The Pictur-
esque in History, 313.

Lord, W. Frewen, "Marked Unex-
plored," 664.

Lubbock, Sir John, Buds and Stipules,

565.
Ludicrous, Theory of the, 95.
Ludwig and Modern Physiology, 11.
Luminescence, 191.

Madden, D. H., The Early Life and

Work of Shakespeare, 743.
Magnetic Curve Tracer, 229.

Research at Low Temperatures,

239.

Magneto-Optic Rotation, 703.

Malay States, 754.

Mansergh, J., Bringing of Water to

Birmingham, 679.
Marconi's System of Signalling, 471.
Marine Organisms, 75.
" Marked Unexplored," 664.
Martin, T. C, Utilisation of Niagara,

269.
Metallic Alloys, 409.
Metals, Contact Electricity of, 521.

used by the Great Nations of

Antiquity, 608.

Messel, Rudolph, Donation, 783.
Meteorites containing Diamonds, 499.
Meteors, November, 337.
Metropolitan Water Supply, 53.
Miall, L. C, A Yorkshire Moor, 621.
Microbes in Water, 62.
Milne, J., Recent Advances in Seis-
mology, 326.
Minchin, E. A., Living Crystals, 723.
Moissan, H., Le Fluor, 452,
Mond, L., Donations, 283, 783.
Monthly Meetings : —

(1896) February, 32; March, 78;
April, 147; May, 187 ; June, 235 ;
July, 280; November, 283; De-
cember, 289.

(1897) Februarv, 309 ; March, 350 ;
April, 413 ; May, 434 ; June, 502 ;
July, 508; November, 511; De-
cember, 517.

(1898) February, 602; March, 660;
April, 699 ; May, 732 ; June, 783 ;
July, 789; November, 793; De-
cember, 799.

Morgan, C. Lloyd, Instinct and Intelli-
gence in Animals, 567.
Mortality Figures, 168.
Murat, J., 664.
Murray, John, Marine Organisms, 75.

National Biography, 27.

Niagara, Utilisation of, 269.

Noble, Sir A., Donations, 283, 508, 789,

603.
November Meteors, 337.

832

INDEX.

Northumberland, Duke of, Donation,
289.

Obganic Matter, Circulation of, 157.

Palestine Exploration, 346.

Metals used in, 615.

Petrie, W. M. Flinders, The Develop-
ment of the Tomb in Egypt, 769.

Physico-Chemical Inquiry, Recent Re-
sults, 641.

Physiology, Modern, 11.

Picturesque in History, 213.

Palaeography, Greek and Latin, 375.

Polarisation of Electric Ray, 293.

Poore, G. V., Circulation of Organic
Matter, 157.

Portrait Painting, 36.

Preece, W. H., Signalling through
Space without Wires, 467.

Raffles, Sir Stamford, and the Malay

States, 754.
Rayleigh, Lord, More about Argon, 1.
Re-elected Professor of

Natural Philosophy, 187, 434.

The Limits of Audition, 417.

Some Experiments with the

Telephone, 786.
Refraction of Electric Ray, 300.
Romance, 438.

Romanes, Mrs. G. J., Donation, 783.
Rontgen Radiations, 580.
Rontgen's Researches on Electric

Shadows, 191.

Salomons, Sir David, Donation, 783.
Sanderson, Burden, Ludwig and

Modern Physiology, 11.
Scotland, Early Man in, 391.
Serpents* Venom, Immunisation

against, 107.
Seismology, 326.
Shakespeare, William, Early Life and

Work, 743.
Siemens, A., Cable Laying on the

Amazon River, 217.
Signalling through Space without

Wires, 467.
Singapore, Founder of, 754.
Smithells, A., The Source of Light in

Flames, 366.
Snake Bite, Treatment of, 107.

Solution, Theory of, 409.

Specific Heats, 736.

Sponges, 723.

Stoney, G. Johnstone, The Approach-
ing Return of the Great Swarm of
November Meteors, 337.

Swinton, Alan A. Campbell, New
Studies in Cathode and Rontgen
Radiations, 580.

Telephone, Some Experiments with
the, 786.

Temperatures, Research at Low, 133,
239, 555, 815.

Thomson, J. J., Cathode Rays, 419.

Thompson, Sir E. Maunde, Greek and
Latin Palaeography, 375.

Thompson, S. P., Electric Shadows and
Luminescence, 191.

Thorpe, T. E., Some Recent Results of
Physico-Chemical Inquiry, 641.

Tilden, W. A., Experiments on Chemi-
cal Elements in Relation to Heat,
735.

Times, The, Proprietors of. Donation,
283.

Tomb, Development of, in Egypt, 769.

Trout Stream, 50.

Tunnel under the Thames at Black-
wall, 81.

Turner, Sir William, Early Man in
Scotland, 391.

Tyndall, Mrs., Gift of 1000/. in name of
'Dr. John Tyndall, 602.

Vacuum Vessels, 134.

Vincent, B., Portrait of, Presented, 517.

Viscosity of Liquids, 641.

Vision, Some Curiosities of, 354.

Vitalism, Old and New, 21.

Volta's Discoveries, 521.

Waller, A. D., Elected FuUerian
Professor of Physiology, 283.

Water Supply of London, 53.

Watkin, H., Chronographs, and their
Application to Gun Ballistics, 176

Wesley, John, 233.

Wiedemann's Researches on Electric
Shadows and Luminescence, 202.

YoEKsmBE Moor, 621.

END OF VOLUME XV.

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Vol. XV. -Part I. l-^V %#^. /?

Jaii, 17. 'IHE liiGiiT Hox. Loud Kayleigh— More about Argou?

Jan. 24. Irofessou Burdon Sanderson, M.D. — Ludwig and Moderil

Phy.yioiogy H

Jan. 31. Sidney Lee, Esq. —National Biography .. .. .. .. 1^7

Feb. 3. Oeneral Monthly Meeting .. .. .. .. .. ^i-j,

Fob. 7. The Hon. John Collier— Portrait Painting in its Historical

A.spoots 2>G

Feb. 14. J. J. Aemistead, Esq. — Fish Culture .. .. .. .. ;;<j

Feb. 21. Edward Frankland, Esq.— The Past, I'resent and Future

Water Supply of London . . . . . . . , . . . , f,;;

Feb. 26. John Murray, Esq. — Marine Organisms and their Conditions of

Environment. . . . , . . . . . . . . . . . 7.",

March 2. General Monthly Meeting . . . . 7y

March G. A. R. Binnie, Esq.— The Tunnel under the Thames at Black-
wall . . . . . . . . . . . . .... . . 81

March 13. Wilj.ia.m Sajil el Lilly, Esq, — The Theory of the Ludicrous . . 95
March 20. Professor T. R. Eraser, M D.— Immunisation against Serpents'

Venom a,nd the Treatment of Snake- Bite with Antivenene . . 107

JMarch 27. Professor Dewar — New Researches on Liquid Air .. .. i;j;j

April 13. General Monthly Meeting .. ,. 147

April 17. Professor G. Lippmann — Colour Photography , . . . . . I5i

April 24. Professor G. V. Poore, M.D. — The Circulation of Organic

Matter .. .. .. 157

May 1. Annual Meeting . . . . . . . . 175

May 1. Colonel H. Watkin, C.B. — Chnmographs and their Application

to Gun Ballistics . . . . . . . . . . \ , . . 17(5

May 4. General Monthly Meeting . . . . 187

May 8. Pkofes.^or Silvanus P. Teojjpson — Electric Shadows and

Luminescence' .. .. ., .. .. .. .. 191

May 1 5. Alexander Siemens, Esq.— Cable Laying on the Amazon River 217

May 22. Professor J. A. Ewing — Hysteresis . . . . . . . . 227

May 2y. Augustine Btrrell, Esq. M.P. — John Wesley : Some Aspects of

the Eighteenth Century .. .. .. ., . f ,. 23.S

June 1. General Monthly Meeting . . 235

June 5. Professor J. A. Fleming — Electric and Magnetic Research at

Low Temperatures. . .. .. .. .. .. ., 239

June 19. (Extra Evening). Thomas C. Martin, Esq. — The Utilisation of

Niagara . . . . , . . . . . , . . . . . 269

July 6. General Monthly Meeting . . . . . . . . . . 280

Nov. 2. General Monthly Meeting . . . . . . . . , . 280

Dec. 7. General Monthly Meeting . . . , . , , . 289

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Vol. XV.— Part II.

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1897. PAGE

Jan. 22. Professor Dewar — Properties of Liquid Oxygen . . . . 555

Jan. 29. Professor Jagadis Chunder Bose — The Polarization of the

Electric Eay 293

Feb. 1. General Monthly Meeting 309

Feb. 5. The Eight Eev. the Lord Bishop of London — The

Picturesque ia History 313

Feb. 12. Professor John Milne — Eecent Advances in Seismology , . 326

Feb. 19. G. Johnstone Stoney, Esq. — The Approaching Return of the

Great Swarm of November Meteors 337

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Blarch 1. General Monthly Meeting 850

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Palaeography . . . , 375

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May 1. Annual Meeting 433

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May 21, The Rt. Hon. Lord Kelvin— Contact Electricity of Metals .. 521

May 28. Professor H. Moissan — Le Fluor 452

June 4. W. H. Preece, Esq.— Signalling through Space without Wires 467

June 11. William Cbookes, Esq. — Diamonds 477

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PROCEEDINGS

OF THE

i(oi)al fiu^tttuttou of iSfVeat iijt;

Jan. 21. The Right Ho\. Sir John Lubbock, Bart. M.P. — wasptH4?A8fi'-

Stipules '^X^^^^^^^

Jan. 28. Professor C. Lloyd Morgan — Instinct and lutelligenc^-HH^^ J^

Animuls . . . . . . . . *"567

Feb. i. Alan A. Campbell Swinton, Esq. — Some New Studies in

Cathode and Rontgen Radiations 580

Feb. 7. General Monthly Meeting . . . . . . . . . . g02

Feb. 11. John Hall Giadstone, Esq.— The Metals Used by the Great

Nations of Antiquity .. . .. ,. .. .. G08

Feb. 18. Professor L. C. Miall— A Yorkshire Moop 621

Feb. 25. Captain Abney, C.B.— The Tl;cory of Colour Vi^ion applied to

Modern Colour Photography .'. . . y02

March 1. Professor T. E. Thorpe — ^ome Recent Results of Physico-

Cheniicul Inquiry .. .. .. 641

IMarch 7. General Monthly IMeeting . . . . .... . . 660

March 11. Walter Frewln Lord, Esq. — '• Marked Unexplored"^. . .. 604

March 18. James IMansi^rgh, Esq. — 'I bx; Bringing of AVater to Birmingham

from the Welsh Mountains . , . . . . . . . . 671)

March 25. The Very Rev. Th3 Dean of Canterbury, D.D.— Canterbury

Cathedral . . . . . . . . . . . . . . . . 698

April 1. , Professor Dewar — Liquid Air as an Analytic Agent .. .. 815

April 4. General Monthly Meeting , 699

April 22. W. H. M. Christie, Esq., C.B.— The Recent Eclipse . . . . 810
April 29. Professor Andrew Gray —Magneto-Optic Rotation and its

Explanation by a Gyrostatic Mtdiuni .. .. .. .. 703

May 2. Annual Meeting 722

May 6. Edward A. Minchin, Esq. — Living Crystals 723

May 9. General Monthly Meeting . . 732

May 18. Professor W. A. Tilden— Recent Expeiiments on Certain of the

Chemical Elements in relation to Heat . . 735

May 20. The Right Hon. D. H. Madden— The Eaily Life and Work

. ef Shakespeare . . . . . . 743

May 27. Lieut.-General> The Hon. Sir Andrew Clarke— Sir Stamford

Raffles and the Malay States . . . . . . . . . . 754

June 3. Professor W. M. Flinders Petrie— Tl.e Development of the

Tomb in Egypt 769

June 6. General Monthly Meeting 783

June 10. The Right Hon. Lord Ratleigh — Some Experiments with

the Telephone » . . . . . . . , 786

July 4. General Monthly Meeting 789

Nov. 7. General Monthly Meeting 793

Dec. 5. General Monthly Meeting .. .. .. .. .. 799

Index to Vol. XV. .. .. .. ,. .. .. .. 830

58.

LONDON:
ALBEMARLE STREET, PICCADILLY

• Au(ju§t 1899.

WHSE 00744