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THE

LONDON ano EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

CONDUCTED BY

SIR DAVID BREWSTER, K.H.LL.D.F.R.S. L. & E. &e.
RICHARD TAYLOR, F.L.S.G.S. Astr.S. Nat.H. Mose. &c.

AND

RICHARD PHILLIPS, F.R.S. L. &E. F.G.S, &c.

“Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster
vilior quia ex alienis libamus ut apes.” Just. Lies. Monit. Polit. lib. i. cap. 1.

VOL" Vint,

NEW AND UNITED SERIES OF THE PHILOSOPHICAL MAGAZINE,
ANNALS OF PHILOSOPHY, AND JOURNAL OF SCIENCE.

JANUARY—JUNE, 1836.

LONDON:

PRINTED BY RICHARD TAYLOR, RED LION COURT, FLEET STREET,
Printer to the University of London.

SOLD BY LONGMAN, REES, ORME, BROWN, GREEN, AND LONGMAN; CADELL}
BALDWIN AND CRADOCK; SHERWOOD, GILBERT, AND PIPER 5 SIMPKIN
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LONDON: -—— BY THOMAS CLARK, AND ADAM AND
CHARLES BLACK, EDINBURGH; SMITH AND SON,

GLASGOW , HODGES AND M’ ARTHUR, DUB-

LIN; AND G. W.M, REYNOLDS, PARIS.

Tue Conductors of the London and Edinburgh Philosophical Magazine
and Journal of Science beg to acknowledge the editorial assistance ren-
dered them in the publication of the present volume by their friend Mr.
Epwarp Wim Bray ey, F.L.S., F.G.S., Librarian to the London In-

stitution.

June 1st, 1836.

Vos

cs
Ee
1

Pon
A

CONTENTS.

NUMBER XLIII.—JANUARY, 1836.

Page
Mr. T. W. Jones on the Retina and Pigment of the Eye of the

Common Calamary (Sepia Loligo) .... 1... -2c eee ee even
Rev. W. Buckland’s Notice on the Fossil Beaks of four extinct
Species of Fishes, referrible to the Genus Chimera, that oc-
cur in the Oolitic and Cretaceous Formations of England . .
Mr. J. Tovey on the Relation between the Velocity and Length
of a Wave, in the Undulatory Theory of Light ..........
Dr. J. Inglis’s Extracts from a Prize Essay on Iodine........
Mr. W. J. Henwood’s Observations on the Steam Engines of
Cornwall; in reply to John Taylor, Esq..........+.....-
Dr. H. Hudson on an Error in Dr. Apjohn’s Formula for in-
ferring the Specific Heat of Dry Gases ..............4-
Rev. Baden Powell’s Remarks on a Paper on the Transmission
of Calorific Rays, &c. by M. Melloni, in the Phil. Mag. and
dournal or Science, INOZ42.)... cries cate sees ee herinets
Rev. Baden Powell’s further Observations on M. Cauchy’s
Theory of the Dispersion of Light ..........--..-..+-.
Mr. C. B. Rose’s Sketch of the Geology of West Norfolk .

7
12

20

2)

“

23

24.
28

Mr. W.G. Horner on the Theory of Congeneric Surd Equations 43

Rev. D. Lardner’s Letter to Peter Barlow, Esq., respecting
some parts of his Reports addressed to the Directors and
Proprietors of the London and Birmingham Railway Com-

YE Pfennig hts orf -asg- eee cee tae Nok: wie itn sia ate ta
er. W. Ritchie’s Remarks on. a supposed new Law of Mag-
MeiC ACHON ...... 4. ~ cdg ete meen tonss: o” Br] peLaeesl t=

Dr. Marshall Hall’s Deseliption of a Thermometer for deter-
mining minute Differences of Temperature..............

Official Report of the Proceedings of the British Association
for the Advancement of Science, at the Dublin Meeting,
PASE LOD 0x0 c, 2 = wince Apheieeteel teil a dati ly wise cece aie

Proceedings of the Geological Society sle'«!+ 6 pimeria sive ce fae

—E Lannean SOclety 222. <2) 34 pietaes icin ite

—__—_—___——- Cambridge Philosophical Society ......

Mr. J. D. Smith on the Analysis of German Silver, and the Se-
paration of Zinc from Nickel, &c..... 2.2... pid aee ens

Action of Mushrooms on Atmospheric Air................

mipeciva,.anew Compound ......--. <ignemeantiter iheenns>

Berzelius on the Properties of Tellurium..................

Action of Oxacids on gale ia Apart NirBte of Gana
drogen : F

Seicpfiiic Boukipnnts catch. ods orto ilaaerne.

Meteorological Observations for November 1835 . ‘ :

Meteorological Observations made at the Apartments of the
Royal Society by the Assistant Secretary; by Mr. Thomp-
son at the Garden of the Horticultural Society at Chiswick,
neer London; and by Mr. Veall at Boston

a2

iv "CONTENTS.

NUMBER XLV.—FEBRUARY.

Page
Rev. J. Challis on Capillary Attraction and the Molecular

Forces of Fluids. 1)... 2200 oe sateen 0 t's ee tates te 89
Letter from Peter Barlow, Esq. to the Rev. D, Lardner, on the
Theory of Gradients in Railways...........-++++++-++- 97
Mr. H. J. Brooke on Symbolic Notation, as applied to Minera-
Bid py a kent io ie 0 on teen ee me omens 101
Mr. J. MacCullagh on the Laws of Reflexion from crystallized
Surfacestsy ee eae scone tation, © srettiew ig? occ ne 103

Mr. R. W. Fox’s further Remarks on the Magnetic Forces.. 108

Dr. H. Hudson’s Remarks on M. Melloni’s and Prof. Powell’s
Papers on the Transmission of Calorific Rays inserted in
Lond. and Edinb. Phil. Mag. for December 1835 and Ja-

MBP YB SGS ooo 55 ni Scie eee ot se oe ah = Snel tee ye | ae 109
Rey. Baden Powell on the Theory of Dispersion .......... 112
Mr. Faraday’s Experimental Researches in Electricity. Tenth

Sth Ce ys pee a bee eine ener eet cnr ic Radice 114
Mr. T. T. Grant’s Experiments on the Protection of Iron from

the Action of Salt Water ...... 2.2.2... eee e ee ee eee es 128
Mr. E. Solly on the Conducting Power of Iodine, Bromine,

BUNT CMOMING LOFPRICCETICIEY 0. wo. since els che ine seep 130
Mr. W. Sturgeon’s Description of the Aurora Borealis of No-

WERDER BG, PAGO. a cn te c'eysciee sory mat ce sm ce ee sin tel 134

Mr. John Taylor on the History of Rotatory Single Steam
Engines working expansively; in reply to Mr. Henwood.. 136
Mr. S. Woodward on the Crag Formation; in answer to Mr.

Chiarlesworth's Heply.. 22 eo citar Seavey eo 3m aye ep ected 138
New Books :—Prof. Wheweli’s Remarks on an Article in the
Quarterly Review on Newton and Flamsteed............ 139

Proceedings of the Royal Society ( Anniversary, Nov.30, 1835) 147

— Geological Society .............2+.... 156
Ss Zoological Society. ..:.\ jy t.icade eae see 161
An Cical x periment +. s/o a fees pain 2) che olay pote she, os ee 168
MME ANG POEROONCe 5 Pickler Lye oe nice ohooh’ Lekota) afoteere fe 169
On the Mirage, as seen in Cornwall.............5....0006 169
Subsidiary Hypothesis to the Electro-chemical Theory of Sir
RITE DUE VEIN. S verate Renee setae inte ceric pieehgnme ret 170
Note on Mr. Challis’s Paper on Capillary Attraction ........ 172
i. Dreithaubts Mineralogy. 2200. ccc cin cre ae cece od ome 173
Pralleyis MEUMIEb ihn. act ce wile, Pepe nls kecfesit vite ster See 173
Dr. Thomson on Sesquisulphate of Manganese ............ 173
M. F. Wohler on Crystallized Oxide of Chromium ........ 175
VOW SSCIENEINC TIQUMB eben. o's'aoivuselsin sc a! > snes atauateletatn 2 175

CONTENTS. v

NUMBER XLVI—MARCH.

Page

Mr. Faraday on the general Magnetic Relations and Characters
Cathe Metals ear eee es. d lorck eae aie eo ckcetoete 177

Mr. Woodbine Parish on the Effects of the Earthquake Waves
emtne Cossiar tie Pactie.. 34. <4. - « s «paaee ms cape. 181

Rev. B. Powell’s Note on the Transmission of Radiant Heat.. 186

Mr. J. Atkinson on Sir G. S. Mackenzie’s Remarks on certain
Points in Meteorology, &c., inserted in Lond. and Edinb.

fie wiag, tor November 1835.2... 6... - g++ se cacle se = 187
Mr. H. F. Talbot on the repulsive Power of Heat .......... 189
Dr. J. Inglis’s Extracts from a Prize Essay on Iodine........ 191

Sir D. Brewster on the Anatomical and Optical Structure of the
Crystalline Lenses of Animals, particularly that ofthe Cod 193
Prof. R. Wagner’s Observations on the Compound Eyes of In-

SOC Bogakaoaec ends Ob SU nn DOP CODE boE bo t> Fo Obdeor 202
Rev. Baden Powell on the Formula for the Dispersion of Light
derived from M. Cauchy’s Theory .::....5....5....2.% 204:

Rev. W. Whewell’s Remarks on a Note on a Pamphlet entitled
« Newton and Flamsteed” in No. CX. of the Quarterly Re-
TAT ORTe i Rl pe) He deeb MN stash aes St aan easel at aes Cie clan hares J 11
Prof. S. P. Rigaud’s Observations on a Note respecting Mr.
Whewell, which is appended to No. CX. of the Quarterly

RBC ee AEA East Che SEL DE © soca v5 4) aserage ee oie oe 218
On Whiston, Halley, and the Quarterly Reviewer of the “ Ac-
faq OLE AIGPLEC OL Fel Bare ee es oN ote Be orcteie 225

Mr. W. Hopkins’s Abstract of a Memoir on Physical Geology;
with a further Exposition of certain Points connected with
“TENSE Pel aA? NA ROR caine en sh Pe a 227

Rev. Dr. Robinson on the Aurora of November 18th, 1835.. 236

Mr. W. H. Barlow’s Account of Experiments made at Con-
stantinople on Drummond’s Light, for the purpose of Light-

house I]lumination in the Black Sea.................... 238
Rev. W. Ritchie’s Additional Remarks on the Law of Mag-
netic Attractions and Repulsions..................--.. 242

Mr. W. S. Woolhouse on the Theory of Gradients on Railways 243
Prof. Forbes’s Noter especting the Undulatory Theory of Heat,

and on the Circular Polarization of Heat by Total Reflexion 246
Dr. Daubeny’s Reply to some Remarks contained in Dr. John

Divewe, Lue of pit TF, Davy te ee olen teb ie vcs dare oe 249
Proceedings of the Linnzean Society ...............-000- 255
——_ Gibraltar Scientific Society —New Obser-

Watery at aims ar Baths sie Seno a. soy eine de bee 256
M. Mitscherlich on Nitro-benzide and Sulpho-benzide ...... 257
M. Mitscherlich on the Formation of Aither.............. 258

Mr. J. D. Smith on the Separation of Barytes and Strontia .. 259
Mr. J. D. Smith on the Composition of Carbonate of Zinc.... 261
Prof. Del Rio on Riolite, a supposed Biseleniuret of Zinc, and
Herrerite, supposed to be Carbonate of Tellurium,....... 261
Meteorological Observations ...00 000. J Ueccecscccsccccs - 268

vi CONTENTS.

NUMBER XLVII.—APRIL.

Page

Mr. J. de C. Sowerby’s Observations upon the Habits of the
Plecotus auritus, or Long-eared Bat.............-0+04. 265

Mr. G. Schweitzer’s Observations on the frequent Presence of

Lead in English Chemical Preparations; on the Cause of
that Presence; and other Remarks relative thereto ...... 267
Mr. J. Tovey’s further Researches in the Undulatory Theory
GP gtr: & .y..c'< nies shee cian te eee eedesaiay nis ea Tels ieee
Mr. W. Hopkins’s Abstract of a Memoir on Physical Geology;
with an further Exposition of certain Points connected with

270

GE SGD Ct, nae ey aracd SER eae eaiels = jake a eae 272
Mr. J. T. Graves on the lately proposed Logarithms of Unity,

in. Reply.to Prof De Morgan... 5 oc 6.4.2 00 n> % ani balmiee 281
Rev. Prof. Challis on the Phenomena of Drops of Oil floating

TL LAT 1 RES ET oan rh Sema er ys Caries” - 288
Mr. P. Barlow’s Remarks on Lieutenant Lecount’s Treatise on

PEGI AR AMUAS 2 00 Sha, ots chokes Sie ty ainsait Sky of a ain Syord Bele Lee 291

Mr. T. Squire on the Solar Eclipse of May 15th, 1836, parti-
cularly as it will be seen at Alnwick, in Northumberland .. 293
Prof. J. R. Young’s Observations upon Mr. Woolhouse’s Theory

Of Wena SP LACtGNS We. hie fannie, 9 sg hh ssa: crete See 295
Mr. C. Fox on the Construction of Skew Arches .......... 299
Rev. Baden Powell’s further Observations on M. Cauchy’s

Theory of the Dispersion of Light.................... 305
Proceedings of the Geological Society, (Anniversary Address

of Charles Lyell, Esq. President) ...........000...0000: 310
——___—__—_——_ Linnean Society; Zoological Society 345-346
——— at the Meetings of the Royal Institution ...... 348
On the Attractive and Repulsive Forces of Magnets at very

BIMAL AVISEANEES 2 < widis wois ayrinyesk stir = 40 ci tiecaper ee inten thet oe 349
On the Aurora of the 18th November last ..............,. 350
Note on Mr. Atkinson’s Paper inserted in the last Number of

our Journal mage NSB oe. to n.< st-\m.nssisielaposave esleltS/ctee ie Cer rope |
Meteotological Observations, . . ....0).(..2.66 se jee 91900 2 80 351

NUMBER XLVIII.—MAY.

Dr. R. Kane on the Action of Hydrochloric Acid on certain
Sulphates, and particularly on the Sulphate of Copper.... 353
Mr. W. Hopkins’s Abstract of a Memoir on Physical Geology;
with a further Exposition of certain Points connected with
the Subject (continued)........... steaiats. sated perl 9 ea 357
Sir Philip de Malpas Grey Egerton’s Catalogue of Fossil Fish
in the Collections of Lord Cole and Sir Philip Grey Egerton,
arranged alphabetically; with References to the Localities,
Geological Positions, and published Descriptions of the
SUE R awe cas aU IEE Piles te rtm. ys. tle hee ta 366
Mr. C. Rumker on a new Method of reducing Lunar Obser-
vations for the Determination of the Longitude,......... 373

CONTENTS. vil

‘ Page
Sir D. Brewster’s Observations on the Lines of the Solar Spec-
trum, and on those produced by the Earth’s Atmosphere,

and by the Action of Nitrous Acid Gas .....-.+--+-.--- 384
Mr. W.S. B. Woolhouse on the Theory of Vanishing Fractions,
in Reply to the Observations of Professor Young ........ 393
Mr. E. Solly’s further Experiments on Conducting Power for
Electricity ee. . ~~ sup» = fale Sate OSU, 1 Ia oe -. 400
Reviews, and Notices respecting New Books: — Young's
Theory and Solution of Algebraic Equations .......... 402
Weigmann’s Herpetologia Mexicana ........+.+++++- 410
Cooper’s Flora Metropolitana ........-.+00++- +1008 411
Samouelle’s Entomologist’s Useful Compendium, 2nd Edit. 412
Proceedings of the Royal Society.........-...--+++40-: 412
aS TSS SE en eek Sate ac 423

Royal Society of Edinburgh—Dr. Hope's

Address on presenting the Keith Medal to Prof. Forbes, for

his Experiments on the Refraction and Polarization of Heat 424

Cambridge Philosophical Society ...... 429

Camden Philosophical Institution ...... 43)

Sir John F. W. Herschel’s Views on Scientific and General
Education, applied to the proposed System of Instruction in

the South-African College ........ 22-25. -e eee ee ee -» 432
On the Aurora Borealis of November 18, 1835, as witnesse

at Collumpton in Devonshire, by N.S. Heineken=.:.4::... . 439
Lieut. Lecount’s Reply to Mr. Barlow............+---00.- 439
Botanical Society of Edinburgh ...........--.4---00---- 440
Inquiry relative to Dr. Pemberton’s Translation and Illustra-

tions of Newton’s Principia, by Prof. Rigaud ............ 44]
On Suberic Acid and its Combinations ................ 22 443
Phloridzine;—Thebaia, a new Alkali in Opium............ 444
New Renal Calculus........-- PSE As RO. PUNTO US 2 SS 446
Solidification of Carbonic Acid ................42 eee. 446

Arsenovinic Acid—Meteorological Observations

NUMBER XLIX.—JUNE.

Prof. Forbes on the Mathematical Form of the Gothic Pendent 449
Rev. Prof. Ritchie's Experimental and Physical Researches in
Electricity and Magnetism .......... ee a ee 455
M. Cauchy on a New Formula for solving the Problem of In-
terpolation in a Manner applicable to Physical Investigations 459
Sir D. Brewster on the Colours of Natural Bodies.......... 468
Rev. J. H. Pratt on the Proposition that a Function of @ and
can be developed in only one Series of Laplace’s Coeffi-
cients; the Function being supposed not to become infinite
between the Limits o and x of 6’ and o and 27 of W
Mr. Faraday on a supposed new Sulphate and Oxide of An-
TUMIOIY . sa te ewe ciclo eelabe + "5 nea. d he Remap a 26 © 476
Mr. J. Nixon’s Table of observed Terrestrial Retractions .... 479
Mr. J. Blackwall’s Characters of some undescribed Species of
ATOM .....0000: posarvtengnicsahscerene Mare an vein Meee

Vill CONTENTS.
: gue, bs Page
Rev. P. Keith on the Conditions of Germination, in Reply to

MaDeGandolle sates. 3.50. ccc). ils coe ee eee obots lle ater 491
Dr. R. Kane’s Experiments on the Action of Ammonia on the
Chlorides and Oxides of Mercury, and on the Composition

of White Precipitate’. >...) kyips slgade.s six's «IES. a ateseia lee 495
Mr. Tovey’s Researches in the Undulatory Theory of Light,
in continuation of former Papers..............+++- e006. 500

Mr. Beke on the former Extent of the Persian Gulf, and on the

Non-identity of Babylon and Babel; in Reply to Mr. Carter 506
Prof. Young on the Theory of Vanishing Fractions --...... 515
Mr. Faraday on the History of the Condensation of the Gases,

in Reply to Dr. Davy, introduced by some Remarks on that

of Electro-magnetic Rotation ....... 056. ccec0. scien 521

SUPPLEMENTARY NUMBER.

Mr, Charlesworth on the Crag of Suffolk, and on the Fallacies
connected with the Method now usually employed for ascer-
taining the relative Age of Tertiary Deposits ............ 529

Sir W. R. Hamilton’s Theorem respecting Algebraic Elimina-
tion, connected with the Question of the Possibility of re-
solving in finite Terms the general Equation of the Fifth
WSR WER I tet Wieds eae a) fo wien posto alba dent 1s hake APRS ofa /u 0 Bisbee. sh 538

New Books :—Webster’s Principles of Hydrostatics; and

Theory of the Equilibrium and Motion of Fluids........ 544

Proceedings of the Royal Society 22.02.20 0..0.. sete ol 545
a Geological Society ........ satel Bec ee 553
Sa SS ean OcIeey. iio heee Oa oc Shee 580
On the Properties of Liquid Carbonic Acid................ 583
Ataalrama|tion of Zin’ Piatesety .! 70245 ciao Hah tie ola Bom 585
Crystallized Oxichloride of Antimony..............06..4- 585
M. Guérin-Vary on Potatoe Starch ................000.5- 586
Artificial Camphor or Camphogene...................00- 588
NEW 4ACIO. OL STGIBIOE 7. co. 4.0. ic:e-s aternn' =o reels aE o.. Riblale s 588
Observations on the Eclipse of May 15, 1836.............. 589
Figeite ne Panett aso rye Aw pela ants aye ocala MnRe os, «e's = coe oan 591
Note respecting certain controversial Communications lately
sent for insertion in this Journal ...................... 591
Meteorological Observations............-... 202. eeeeee 592
Pndexty.'\o-uimyme es is Se A ee ee ets oe 594
PLATES.

I. A Plate illustrative of Mr.'T. Warton Jones’s Paper on the Eye of
the Sepia Loligo.

IJ. A Plate illustrative of Sir D. Brewsrer’s Paper on the Crystalline
Lenses of Animals, and of Prof. Wacner’s Observations on the
Compound Eyes of Insects.

ILI. A Plate illustrative of Mr. C.Fox’s Paper on the Construction of
Skew Arches.

IV. A Plate illustrative of Prof, Fonszs’s Paper on the Gothic Pendent.

ee. Ce a ¢ er ” 7. : = . hoe ra :
, , Pr a a ~ E
oe Lon. bEiin fiat. Mag Vol.8. FEI,
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4 = P. *
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.
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.

. EYE OF PUK SEP LA I OLdG@a.

Sri fod by wart & Soreé

ee ae ee ee ee

THE

LONDON ano EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.)

JANUARY 1836.

I. On the Retina and Pigment of the Eye of the Common Cala-
mary (Sepia Loligo). By'THomas Wuarrton Jones, Esg.*

JN the eye of the Cuttlefish tribe, the retina is said to be si-
tuated behind a thick layer of dark pigment. As such a
structure would have the effect of intercepting more or less
completely the rays of light, the strangeness of it has particu-
larly attracted the attention of the physiologist and optician.
The eye in the Cephalopodous Mollusca presents several ano-
malies when compared with that of the Vertebrata, but I am
inclined to think that the structure just mentioned is not one
of them. This is at least the case in the eye of the Sepza
Loligo, which I have carefully examined ; and what is found in
one species probably also exists in the other genera and species
of the order.

My dissections and microscopical examinations of the eye
of the SepiaLoligo show, that what has hitherto been described
as pigment is in reality not so, but a nervous expansion of a
peculiar texture, tinged of a reddish brown colour—a circum-
stance which has given rise to the error of supposing it merely
pigment. Before describing the structure of the retina, it will
not be out of place first to notice the optic nervous apparatus,
which differs remarkably from what is observed in the Verte-
brata. In connexion with the cerebral ganglion, on each side,
is a large nervous mass, or ganglion, from which fibrils pro-
ceed in a peculiar manner to the eyeball. On either side of the
nervous mass, or optic ganglion as it may be called, the fibrils

* Communicated by the Author.
Third Series. Vol. 8. No. 43. Jan. 1836. B

2 Mr. T. Wharton Jones on the Retina and Pigment

arise, and immediately after their origin intercross with each
other, those from the one side going to the opposite side of
the eye, and contrariwise. The nervous fibrils from the fore
end of the ganglion do not intercross, but proceed directly to
the eye. The fibrils which thus arise from the optic ganglion
are in very great number. They cover to a considerable ex-
tent the posterior surface of the eyeball, and each penetrates
singly the thin cartilaginous lamina which corresponds to a
sclerotica. The optic fibrils having thus entered the eyeball
expand into a layer of a light reddish-brown tinge, which I
shall distinguish by the name of the first layer of the retina.
What I call the second layer of the retina, is the reddish
brown membrane, which, I have already mentioned, is the
part usually considered as pigment. It is situated within the
first layer; and betwixt the two there intervenes a pretty thick
and dark layer of pigment, through apertures in which the
nervous substance passes from the first layer of the retina to
form the second. Examined with the microscope, the second
layer of the retina, which, as I have said, is of a reddish
brown colour, is observed to be composed of short fibres per-
pendicular to its surfaces. These fibres, towards the inner
surface, end in a delicate pulpy nervous substance, also tinged
of a reddish brown colour, particularly on its inner surface,
which has a corrugated or papillary appearance.

I think it unnecessary to notice further the structure of the
eye of the Calamary, but shall content myself with referring
to the annexed figures (Plate I.) and their explanation.

Since writing the above I have examined the eye of an
Octopus, and have found the retina and pigment to possess the
sume structure as in this Calamary.

Explanation of the Plate.

Figure 1. Represents the brain and two eyes of the Sepia
Loligo. On the right side are seen the optic ganglion, and
the fibrils which arise from it expanding themselves- on the
back of the eye previously to their penetrating the sclerotica.
On the left side is a horizontal section of the eye and optic
ganglion.

a. Cerebral ganglion. 6. Subcesophageal ganglion. c. A
black probe introduced into the nervous collar, through which
the cesophagus passes. d. Optic ganglion of the right side:
e, e,e. The nervous fibrils which arise from it and enter the
eye to form the retina. ,f Optic ganglion of the left side cut
horizontally. g, g. Optic fibrils arising from the ganglion and
penetrating the sclerotica at different points. A, 4, 4, h. The

of the Eye of the Common Calamary (Sepia Loligo). 3

sclerotica, which is cartilaginous. 7,2. A cartilaginous part,
which may be compared in some respects to the cornea of the
Vertebrata. It has a large opening in its centre, through which
the lens projects. 4, 4. A thin membrane which lines the inner
surface of the preceding part, and extends a little beyond the
edge of the opening in it. This membrane, which is covered
on its inner surface with a dark pigment, may be looked on as
a kind of iris. It is reflected on the anterior surface of the
structure which supports the lens, and is continuous with the
outer lamina of the anterior segment of the latter. J, J, 7,1. A
silvery-like membrane, which may be called the conjunctiva.
m,m. Kirst layer of the retina. Opposite that part where the
optic fibrils cover the back part of the eye, this layer of the
retina is joined by the fibrils immediately on their entrance,
but further forward the fibrils run a little way within the
sclerotica before joining the retina, which produces the ap-
pearance of another layer. m, ”. Second layer of the retina.
0,0. Pigment situated betwixt the two layers of the retina.
p- The lens. It is a sphere divided into two unequal seg-
ments, an anterior smaller, and a posterior larger. Betwixt
the two segments is interposed a thin transparent membrane q,
which is continued from the first layer of the retina, and is
joined by athin membrane r, which arises from the sclerotica.
The lens, as in the Vertebrata, is composed of laminz and
fibres. The outer laminz of the lens are continued into a
plicated structure situated around its circumference, on
either surface of the membrane which is interposed betwixt
the segments of the lens. s,s. A transparent membrane,which
may be called the hyaloid. It does not, however, completely
inclose the aqueous fluid which represents the vitreous hu-
mour. ¢. A cartilaginous pulley, through which play the sub-
divisions of a tendon u, common to a membraneous muscle
surrounding either eyeball.

Figure 2. Shows the intercrossing of the optic fibrils after
their origin from the optic ganglion.

Figure 3. A section of the layers of the retina magnified.

a. The optic fibrils joining 6. the first layer of the re-
tina. c. The pigment interposed between the first and second
layers. d. Second layer of the retina, composed of short fibres
perpendicular to its surfaces. e. A pulpy nervous substance
in which the fibres end on the inner surface.

Sha re

II. Notice on the Fossil Beaks of four extinct Species of Fishes,
referrible to the Genus Chimera, that occur in the Oolitic
and Cretaceous Formations of England. By the Rev. WM.
Buckianp, D.D. F.G.S., Professor of Geology and Minera-
legy in the University of Oxford.*

BOUT six years ago, Sir Philip Grey Egerton procured

from the Kimmeridge clay of Shotover Hill, near Oxford,

five remarkable fossil bodies of most curious configuration, in

some degree resembling beaks of Cuttlefishes and Turtles, but
not reducible to any known form in either of these families.

In 1832, the Rev. C. Townsend of Great Milton, near Ox-
ford, discovered in the Portland stone of that village another
series of bones, resembling those from the Kimmeridge clay,
but very much larger, and of a different species.

On my submitting these specimens to Mr. Mantell, he im-
mediately compared them with three similar bones in his collec-
tion,—one from the Chalk marl of Hamsey, and two from the
Chalk near Lewes. These were obviously the same parts of
two other species of animals of the same genus. That from
the Chalk marl had been shown by him to Cuvier, who could
only recognise in it a distant resemblance to the articulating
posterior portion of a jaw of a Saurian; but this resemblance
was not maintained in the more perfect fragments of other
species which had come into my possession from the Kimme-
ridge and Portland beds.

Mr. Mantell permitted me at this time to prepare a draw-
ing of the fragment from the Chalk marl which he had sub-
mitted to Cuvier.

After searching in vain through the best collections in Lon-
don, and consulting our best comparative anatomists, I could
find no animal whose beak or jaws corresponded with either
of the forms of fossil bones under consideration.

During the last five years I have lost no opportunity of
submitting these fossils to skilful comparative anatomists, and
with the same result. My exhibition of several of them to
some of the most distinguished anatomists of Germany, at the
meeting of the Naturforscher at Bonn in September last, threw
no further light upon the subject. The nearest approxima-
tion that was suggested to me came from Professor Carus,
who advised me to compare the two smallest of these fossils
(evidently a pair) with the beak of a Tetrodon.

In pursuance of this advice, I examined all the Tetrodons
in every museum I visited after my departure from Bonn,
and arrived at no other conclusion than the assurance that

* Communicated by the Author. This paper was read before the Geo-
logical Society on the 4th of November, 1835.

On the Fossil Beaks of four Species of Chimeera. 5

not one of these supposed fossil beaks could be referred to
that genus.

In examining the rich collection in the museum at Leyden,
a few days ago, with my friend Professor Van Breda, I found
by the side of a Tetrodon a skeleton of that rare fish the
Chimera monstrosa, of which I had never before seen the bones,
and instantly recognised in the upper and lower jaws of this
animal the object of my long research. The two intermaxillary
bones of the upper jaw corresponded with the pair of tooth-
like bones from the Kimmeridge clay, which I had in vain
compared with the teeth of the Zetrodon; the superior
maxillary bones corresponded with a second pair of the
fossil bones from the same clay ; and the lower maxillary of
the Chimera presented the form of the fossil inferior maxil-
lary bones of my four different species from the Portland
stone, Kimmeridge clay, Chalk marl, and Chalk.

This discovery of the type of each of these new forms of
fossil bones in the mouth of a living species of Chimera, at
once clears up all the difficulties of which I have so long been
seeking the solution, and enables me to announce the exist-
ence of four fossil species of a genus hitherto unheard of in
the annals of Paleontology; one in each of the following
four different formations, namely, the Portland stone, Kim-
meridge clay, Chalk marl, and Chalk. To that discovered in
the Portland stone; I propose to give the name of Chimera
Townsendii ; to that in the Kimmeridge clay, Chimera Eger-
tonii; to that in the chalk marl, Chimera Agassizit; and to
that in the chalk, Chimera Mantelliz.

On my submitting these fossils to Professor Agassiz, he at
once admitted them to belong to the genus Chimera, a genus
of which the living individuals are extremely rare, and of
which he knows not where a single prepared skeleton exists,
except in the museum at Leyden.

The only known living species of the genus Chimera is
widely diffused, and- is usually found pursuing herrings and
migratory fishes: it lives chiefly in the northern seas, and
occurs also in the Mediterranean. It is most nearly allied to
the family of Sharks, and is from two to three feet long. The
cartilaginous nature of its skeleton explains the reason why
no other bones of the fossil Chimera have been found, together
with those that form their very peculiar jaws. The hard horny
plates which cover these jawbones in the living species, and
perform the office of teeth, are in none of our fossil specimens
preserved. ‘The two intermaxillary bones of the upper jaw
of the Chimera Lgertonii have nearly the hardness of enamel,
and appear to have had no separable horny covering: the

6 Dr. Buckland on the Fossil Beaks of four extinct Species

superior and inferior maxillary bones of the same species
exhibit rugous surfaces of attachment, from which their horny
coverings have been removed. The same marks of attach-
ment are seen in the lower jaw-bones of the Chimera Agassizit
and Chimera Mantellii. The horny investment of all these
bones has evidently fallen off and perished, like the horny
covering which separates readily from the bony beak of Tur-
tles, and which is rarely, if ever, found with the bones of
fossil Testudinata.

The genus Chimera is one of the most remarkable among
living fishes, as a link in the family of Chondroptérygiens.
The fact of the existence of many fossil species of this curious
genus (and some of these much larger than the single known
existing species) in such early periods as those of the Oolitic
and Cretaceous formations leads to important considerations
in Physiology.

Professor Agassiz has at my request prepared the following
description of the four fossil species which form the subject of
this communication. Further details and figures will be pub-
lished by him in the eighth number of his Pozssons Fossiles.

Note by Professor Agassiz.

The discovery of the genus Chimera among. fossil fishes
is one of the most interesting and unexpected.

Recent Chimeras are very little known, and have been ar-
ranged in the order of cartilaginous fishes, but their organi-
zation, and especially the structure of their skeleton, has not
been sufficiently studied. Dr. Buckland’s discovery will draw
the attention of Ichthyologists in a particular manner to this
singular family. ‘The four fossil species about to be enumer-
ated differ essentially from each other, and are considerably
larger than the living. Unfortunately the fossil fragments
which we now possess are far from being complete; only the
jaws of these curious fishes have hitherto been discovered, and
principally the lower jaws.

In the Portland species, the Chimera Townsendii, which is
the largest, the inferior maxillary is very large, short, and
proportionally much thicker, the groove of the symphysis of
its two branches shallower, and the cavity of the dental edge
broader than in the other species; its exterior surface is con-
vex and furrowed longitudinally with shallow wrinkles. The
intermaxillary bone is much bent.

In the Chimera Egertonii the inferior maxillary is short
and flat; its snout is truncated, and in proportion very large ;
the cavity of the dental edge is very wide and the groove of its
symphysis very deep; the intermaxillary is much bent, and

of Fishes referrible to the Genus Chimera. e

the dental edge truncated and square; the superior maxillary
is irregularly triangular, much elongated, and contracts in-
sensibly towards its dental extremity, which is bifid.

In the Chimera Agassizii of Dr. Buckland the inferior
maxillary is the most regular in form of the four species; it is
nearly square, and has the dental edge slightly open; the sur-
face of the symphysis is flatter than in the other species.

The Chimera Mantellii has the inferior jaw straighter and
thinner: its exterior surface is perfectly smooth and flat; its
snout is much elongated and pointed, and the cavity of the
dental edge wider.

Since Dr. Buckland’s discovery of the above four species,
I have found a fifth in the collection of Mr. Greenough, which
differs considerably from them all, in the extreme shortness of
the lower jaw, the length of which is less than its height.
The symphysis of the lower jaw is flat; the dental margin
truncated and grooved in its hinder part. The external sur-
face is smooth; the middle of the inner surface concave; the
intermaxillary is flatter than in the Chimera Egertonii, and
terminates in a straight point. The superior maxillary is
shorter than that of the Chimera Egertonii.

I propose to give to this species of so remarkable a genus
the name of Chimera Greenovii. The locality of this fossil
is unknown.

Oxford, Oct. 27, 1835.

III. On the Relation between the Velocity and Length of a

Wave,.in the Undulatory Theory of Light. By Joun
Tovey, Esq.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

[X the last volume but one of your Magazine, the Rev. Pro-
fessor Powell presented us with an abstract of the essential
principles of M. Cauchy’s View of the Undulatory Theory of
_ Light; by which, as Mr. Powell says, it appears “ that a rela-
tion between the velocity and length of a wave is established
on M. Cauchy’s principles, provided the molecules are so
disposed that the intervals between them always bear a sensi-
ble ratio to the length of an undulation.” vol. vi. p. 266.
Since I first read this, I have arrived at the same result as
M. Cauchy by a less complicated method, which I proceed
to lay before you. Ido this with diffidence, having read
scarcely anything on the subject besides the abstract above
mentioned and Professor Airy’s tract. Should you deem

8 Mr. Tovey on the Relation between the Velocity and

my method worthy of a place in your Journal, I shall pro-
bably send you a continuation of the subject.

Let m,m’, m', &c. be the masses of the particles of ether;
let the rectangular coordinates of m be 2, y,2; those of m’,
xv+Axr,y+Ay, z+ Az; of m', r+ Az’, yt Ay, z+Az, &e.
Let r = /(Az?+ Ay?+3s?), 7) = /(Aa!?+ Ay’? + Az’?), &c.
Suppose the masses to be all equal, and the force of one par-
ticle on another to be a function of their distance multiplied
by m3; and suppose each particle to be influenced only by the
attractions or repulsions of the other particles; then as the
cosines of the angles which 7 makes with the positive direc-

A A A seh
tions of z, y, 2 are =, —, = we have (by the princi-

ples of statics), when the system is in equilibrium,

m= me Aai=s0; mz, £1) Ay = 0,
me 20) he O (1.)

The sums = extending to all the particles within the sphere
of the attractive or repulsive influence of the particle m, which
may be any particle of the system.

Now, suppose the system to be disturbed, and that at the
end of the time ¢, the displacements of m, in the directions of
2, Y, % be &, 7, $; and those of m’, E+ AE, y+Ayn, $+A’; and
suppose Aé, Ay, A to be so small that we may neglect their
squares and rectangles; then the distance of these particles
being r+ Ar = oy [(Axv+A£)?+ (Ay+An)?+(Az+A8)*],
we have
_ ArAf+ AyAn+ Az AE

Ps
The cosines of the directions which » + Ar makes with those
Axv+Ake Ay+An Az+AT.
r+Ar? r+Ar? r+Ar ’
write X, Y, Z for the sums of the components of the forces
acting on m, in the directions of 2, y, z, we have

Ar

of z,y, z will be and if we

he J (r+4r)
= 7 2 Sis der (Aaw+ A€),

“4A
Yame, SOTA ay san) (2.)

T= m2 Lets) (Az+AQ).

Length of a Wave, in the Undulatory Theory of Light. 9
df (r) Inge Sd Ar

Now,f(r+Ar) = f(r) += Ar FERp eT Ro gm
consequently, 2
(r+Ar) mein). (2 Ces oO :
Pg Ast Aes at (Ce 2D) ar}
(Ax + Aé)
=O nay LO) a gy (one i)

(ArAEt+AyAn+Az 8) Az,
by substituting for Ax its value previously found.

If in this expression we write ¢ (7) for a, wv (r) for
(4 ote

3 dy an and substitute it in the first of the equa-

tions (2.), we shall have by virtue of the first of the equa-
tions (1.),

X=ms.{o(r)AE+ (r) (ArAE+AyAn+AzA$) 2}.

The second and third of the equations (2.) are similar to
the first, consequently if we transform them in the same man-

vats f @E dy
ner, and (by the principles of dynamics) put WP? dP
oe.
qe for X, Y, Z, we shall have

23 = m=.{o(r)AE+U(r).(ArAg + AyAy + AzAS)Ar},
d*y

ape E.{o(r)Ant(r). (AvAg+ AyAn+ AzAg)Ay}, (3.)

os = mE Lo(r)AL+ (7) . (APE + AyAn) +AzAd)As}.

From these general equations, a number of integrals,
adapted to particular cases, may be found. Let us suppose
the vibrations of the particles to be performed in straight
lines, all in one direction. This is a case of polarized light.
Let x be taken in the direction of the vibrations; then y and ¢
will be zero, and the first of the equations (3.) will give

iM
26 = mz. {o(r) + (rr) Aa} AE. (4.)

Third Series. Vol. 8. No. 43. Jan. 1836. C

10 Mr. Tovey on the Relation between the Velocity and
Now, let £ be a function of x and ¢, then for AE we may

PE Az? dE Ag aE det
dz ae) ae dB 23 “<d#° 93.4.

If we substitute this value of A £ in equation (4.), and sup-
pose the particles to be so arranged in their state of equili-
brium that for every particle on one side of m, within the
sphere of its influence, there is another at an equal distance
on the opposite side, we may divide the sum © into two parts,
one comprehending the positive values of Az, and the other
the negative; and for every term in one part we shall have a
term equal to it, and involving the same power of A z, in the
other. But in the one part all the terms involving odd powers
of A z will be positive, and in the other all negative; conse-
quently all these terms will vanish: the other terms being
all positive, the sum of one part will be equal to that of the
other. Consequently equation (4.) will become

d? ad? 4 2
a2 = mE (r+ 0 ("Aa pa2(TE as ss - =a)

the sum, in this equation, extending only to the positive
values of Az.

For m=. {$(r)+(r) Az*} Az*, write s*, and for m=.

{> (r)+(r) Ax*} Azt write s’*, then the last equation will be
2 2 4

ae ae ey th (5.)
t dz dz

If we omit the last term, this equation becomes exactly of
the same form as that for the transmission of sound, and gives
then no relation between the length and velocity of the waves.
But if we integrate the equation as it is, we shall obtain a re-
lation of this sort; and this relation will afford a theory of |
the dispersion of light.

As § is a function of z and ¢, it may be expressed by a
series of terms such as p sin t+ q cos nt, where p and g are
functions of z, and ” a constant quantity*. Suppose then
& = psinnt+qcosnt; substitute this value of £ in equa-
tion (5.), and it will become

Il
©

+(9 eee ea et aS od \ ee
q * dz Sait, =e,

* Poisson, T'raité de Mécanique, No. 514, edit. 2.

Length of a Wave, in the Undulatory Theory of Light. 11

This equation must be true for all values of ¢, therefore

@ U d*

ept soe + gp ge =O (6.)
a gl? ds

Wg +878 + gage =O be)

Now, as p is a function of z, it may be expressed by a
series of such terms as a sin kz + 6 cos kz, where a, 6, and
% are constant quantities. Substitutea sini z + bcoskz for
Pp in equation (6.), and it will become

n? —s? fe + % k4 = 0; hence
Ae ae iter k

a Aee aE i si? :
=\/(*= 54") aA tome er art 3 ), nearly.

As the equations (6.) and (7.) are similar, and as we have
put asinkz + bcoskz for p, we must put a! sin £ + b' cos
k z for q; a! and 0! being two more constant quantities. Hence
£ may be expressed by a series of terms similar to

(a sink z+ coskz) snnt+(a' sinkz+0' coskz) cosnt.
With respect to any particular value of z, this term goes
through all its values while ¢ increases by =, and with re-
spect to any particular value of ¢, it goes through all its values

; A Qa -
while z increases by —3 consequently it represents a wave

k
bey pti : OE tn
of light, moving in the direction of z, with the velocity a

the value of which has just been found equal to

Wd gl? )
(0+ s55-)
Professor Powell’s expression for this quantity is

n>

sin( #5")
H , which is equal to H [or aay very

2 BY 4 n
l
nearly. As the Professor considers only one term instead of
the sums s° and s'*, and as rm and J in his notation are the

Qa. : :
same as Az and iy in ours, the two expressions are vir-
/:

tually the same.
C2

12 Dr. Inelis’s Extracts from his Prize Essay on Iodine.
g ‘Y

/2

If we examine the composition of the quantity <~;, we
shall see that the relation between the length and velocity of
a wave does not depend merely upon the ratio of the intervals
of the particles to the length of an undulation, but also upon
the radius of the sphere of their influence.

On the last principle, I think we can (as M. Fresnel seems
to have conjectured*) account for the dispersion of light
without supposing that the waves move with different velocities
in the free setherial medium; to which supposition there seems
to be an insuperable objection+. But I reserve this for future
consideration. In the mean time I hope Professor Powell
will favour us, through the medium of your Journal, with
what he has done towards the verification of M. Cauchy’s
formula, having told us that he is engaged on the subjectt.

I am, yours, &c.
Evesham, Aug. 17, 1835. Joun Tovey.

P.S. In my next communication I believe I shall be able
to show that if the vibrations of the particles of zther be each
decomposed into three rectangular directions, two of which
are perpendicular to the direction in which the light is pro-
pagated, and the other parallel to it, the vibrations in any one
of these three directions may be calculated separately; and
that a satisfactory reason may be assigned why the vibrations
in the direction of propagation are insensible. (Airy’s Tract,
art. 101.)

September 3, 1835.

IV. Extracts from a Prize Essay on Iodine. By JAMES
Ineuis, M.D.

[Continued from p. 444, and concluded. }

N COURTOIS shortly after his discovery of iodine

“e formed the black pulverulent iodide of nitrogen by the
action of iodine upon hydrous ammonia. Gay-Lussac next
described another compound of dry ammoniacal gas and iodine,
which he called the ioduret of ammonia, but which might
rather be called a hydriodate of an iodide of nitrogen. When
this compound is thrown into water, decomposition takes
place, hydriodic acid is found in the water, and the black iodide

* Airy’s Tracts, p. 285, note. t Lbid.

_{{ Notices of Professor Powell’s verifications of M. Cauchy’s modifica-
tion of the undulatory theory, so far as they have yet been made public,
will be found in Lond. and Edinb, Phil. Mag., vol. vi. p. 374; and last vo-
lume, p. 293.—Eorr. }

wr. Inglis’s Extracts from his Prize Essay on Iodine. 13

of nitrogen is precipitated; so that if we suppose it to bea
hydriodate, then we should not require to say that hydriodic
acid and iodide of nitrogen were formed at the moment of so-
lution, but that they existed in the compound ready formed,
and that in consequence of the greater affinity which hydriodic
acid has for water than for the iodide, they separate, and the
iodide precipitates, whilst the acid is held in solution, as I found
to be frequently the case when experimenting on the double
iodides to be noticed hereafter.

If, instead of using the iodine alone with the aqua ammonia,
there be added equal parts of a strong tincture of iodine and
the ammonia, then I found that instead of the dark detonating
ioduret, there was formed an iodide of carbon, similar to that
formed by the tincture of iodine, and the alcoholic solution of
potash. ‘The periodide of carbon by this process is obtained
in pretty large plates. 1 equivalent of ammonia +1 of alco-
hol + 6 of iodine are required, and there result 1 atom of
nitrogen gas (which is evolved and found in the upper por-
tion of the vessel), 1 atom of water, 2 of iodide of carbon, and
3 of hydriodic acid, which latter unites with the excess of am-
monia remaining in the solution. Its presence is indicated by
the addition of bichloride of mercury, and a little muriatic acid
to saturate any excess of ammonia which might redissolve the
red periodide of mercury which is precipitated.

The black detonating teriodide of nitrogen is decomposed
by almost every substance: oils and fatty matter do not cause
its detonation as they do that of the chloride of nitrogen. The
strong mineral acids all explode it when in a perfectly dry
state.

I allowed aqua ammoniz to remain over the iodide of nitro-
gen, in which there was no trace of free iodine, for several
weeks; the iodide was decomposed, almost half of the vessel
in which I had it was filled with nitrogen, and small crystal-
line points were seen floating in the fluid, at the same time that
a yellowish deposition was seen at the bottom. Alcohol when
allowed to remain in contact with the iodide, decomposes it.
Nitrogen is evolved, the liquid becomes of a deep red colour,
and iodide of carbon is formed, the smell of which is per-
ceived in the fluid. Pure water is even reacted on by, or re-
acts with, the elements of this iodide. I found azote given off
as before, the water assumed a ruby tint, and small crystals of
iodine were precipitated.

The most probable cause of the explosive power of the
iodide of nitrogen is this: Nitrogen requires an immense
power to liquefy it. Indeed, by condensation it has never yet
been done; but chlorine and iodine possess this power; the

14 Dr. Inglis’s Extracts from his Prize Essay on Iodine.

tendency, however, is still to regain its original capacity, so
that any substance containing hydrogen, or any other element
which combines with the chlorine or iodine, instantly liberates
the nitrogen, and it expands with a force equal to that which
would be required to liquefy it. * * * *

There is but one hydrocarburet of iodine noticed by authors;
it appears in colourless acicular crystals, and is formed by the
action of olefiant gas on iodine. Faraday, its discoverer,
found it, in composition, quite analogous to chloric ether, and
called it hydrocarburet of iodine +.

After having thoroughly dried a portion of iodine I intro-
duced it into a flask, which was luted on to a gas tube with
sulphate of lime; then the stop-cock was opened, and a constant
supply of gas was thus allowed to enter as fast as the former
was absorbed. Instantly there.is action observed; the small
grains of iodine on the sides of the vessel become semifluid,
and of a dark colour, and the interior of the flask is gradually
filled with ruddy brown fumes. In the course of four hours,
the acicular colourless crystals of Faraday began to appear,
and that in the shade, showing that the direct rays of the sun
are not necessary, as he supposed}. After the gas had been
acting on the iodine for eighteen days I removed the flask, and
observed a fluid at the bottom, which when examined was of
a blackish green colour. It does not combine with water, but
runs into globules like oil, or more exactly like a solution of
iodine in creosote when it is placed in water. On the appli-
cation of the leat of a spirit-lamp to a tube containing this
fluid with the mixture of a drop or two of water, slight ex-
plosions take place, the black liquid is decomposed, a red
fluid rises in vapour, and olefiant gas is evolved. ‘The red
fluid is probably a mixture of olefiant gas and free iodine, for
it instantly casts with starch the characteristic blue tint.

When the black fluid is put into a small retort, and heat
applied, olefiant gas is first driven off, and then a copious ef-
fusion of hydriodic acid; whilst at the same time the orange
red fluid again appears. When the beak of the retort is
placed in water the hydriodic acid is absorbed, and portions
of the red and black fluids come over also; the latter falls ot
the bottom. The water precipitates starch blue, and the per-
chloride of mercury instantly causes the precipitation of the
periodide of mercury. Alcohol removes the substance that
keeps this compound fluid, and the solid green hydrocarburet,

+ See Phil. Trans. for 1821 : or Phil. Mazg., vol. lix. p. 852.—Enir.

} Mr. Faraday certainly formed this compound by exposing iodine and
olefiant gas to the sun’s rays, but he does not explicitly represent that the
“ direct rays” are necessary.—Epir.

Dr. Inglis’s Extracts from his Prize Essay on Iodine. 15

to be spoken of immediately, results. The sulphuric and mu-
riatic acids have no action with the dark fluid, whilst they cause
the decomposition of the red, precipitating its iodine. There
can be little doubt that these two fluids are different com-
pounds, but a limited period prevented any further inquiry.

The next compound to be spoken of is a solid hydrocar-
buret of iodine, sometimes of a dark blackish colour, at other
times, and oftener, of a decided green. It has never been no-
ticed by any chemical author, and differs from Faraday’s in
the following particulars. His is transparent, in white acicular
crystals, shooting out from the sides of the flask, and formed,
as I noticed before, in a very few hours after olefiant gas is
brought in contact with iodine; of a sweet taste, and aromatic
smell]: it fuses and sublimes unchanged. Insoluble in water,
acids, and alkalies; soluble in ether and alcohol, and may be
crystallized from them.

This new hydrocarburet is opake, of a dark green colour,
and not of crystalline texture ; is formed after a longer action
of olefiant gas on iodine; is destitute of taste and smell: it
fuses and is decomposed, giving rise to another new com-
pound, hereafter to be noticed ; and lastly, is insoluble in both
ether and alcohol. Mr. Kemp was the first to discover this
compound, but he has never examined its properties. When
it is first removed from the flask in which it has been formed,
itis mixed with a large portion of Faraday’s hydrocarburet, and
also with the fluids already noticed: these last are allowed -
to drip from it, and then on boiling with alcohol the whole
of Faraday’s hydrocarburet is taken up, and the green com-
pound remains behind, which, after repeated washings with
alcohol, may be considered pure. The former sinks in sul-
phuric acid, whilst the green floats on its surface, and both
are alike unacted on by it. It burns with a clear flame by
heat ; it emits olefiant gas and hydriodic acid, and there re-
mains behind a carbonaceous residue.

At first, from the negative qualities of this green hydrocar-
buret of iodine, I thought it was merely carbon; but I soon
altered my opinion, for I found that by placing this in a
small tube retort, I obtained a perfectly new compound by
distillation. I was led to this process by observing that when
the green hydrocarburet was heated, dense brown fumes
escaped, which emitted the odour of garlic. A receiver was
therefore adapted to the retort, and being kept cool, a liquid
of a deep reddish brown colour collected in it. Whenever
the stopper is removed from the bottle in which it is con-
tained, the room is soon filled with the smell of assafoetida.
It is, like the former, highly inflammable, and consists also of

16 Dr. Inglis’s Extracts fiom his Prize Essay on Iodine.

carbon, hydrogen, and iodine. I have not examined its pro-
perties further, but from its peculiar odour have called it the
foetid hydrocarburet of iodine. * * * *

The compound of sulphur and iodine formed by Gay-
Lussac is most likely merely a mechanical mixture, for after
keeping it in alcohol in a closed vessel for several months, the
alcohol became saturated with iodine, and the sulphur re-
mained unaltered. I tried to procure a chemical compound
in the same way as the chloride of sulphur is formed, but a
similar one to the last resulted. I caused hydriodic acid to
come in contact with the chloride of sulphur; instant reaction
took place,” muriatic acid was formed, and a dark compound,
which was probably an iodide of sulphur, presented itself.
Other means may be had recourse to, as

Hydrosulphuret)) Hyd. Muriat.
ofiodine = { Sulp. acid.
and Tod. Iod. of
chlorine = J Chlo. sulp.

or, by the action of chloride of iodine. on sulphuretted hy-
drogen, there would result, either muriatic acid and iodide
of sulphur, or chloride of sulphur and hydriodic acid.
Having formed the sesquiodide of phosphorus, I laid it
aside in a well-stoppered bottle; it, however, in a short time
attracted moisture from the air, and on removing the stopper
much condensed hydriodic acid burst forth. To get rid of the
fumes, I added a small portion of water, and laid it aside; on
examining it again I found a yellow powder at the bottom of
the fluid. I added now a little more water; but whenever the
red powder came in contact with it, instant decomposition
took place, and much gas was evolved with brisk effervescence,
After the disengagement of the gas had ceased, there still re-
mained a red powder, which being dried and exposed to a
moist atmosphere did not attract moisture; therefore it is
not any of the former iodides. It bears a considerable heat
without change; if, however, it be continued and agitated, it
bursts into flame, and burns with the characteristic appearance
of phosphorus. It is most probably an oxide of phosphorus,
but differs from the following in being darker in colour and
much less inflammable. The oxide of phosphorus, which the
former resembles, is conveniently formed by placing phos-
phorus in a long glass tube, and then heating the tube until the
phosphorus catches fire and liquefies. A current of air is now
made to pass through the tube by blowing forcibly into one
end, vivid combustion ensues, and the whole interior of the

Dr. Inglis’s Extracts from his Prize Essay on Iodine. 17

tube is filled with the yellow oxide. On raising the tube after
the combustion has ceased, from the horizontal to the perpen-
dicular position, a splendid phenomenon takes place; a bright
red glow of light commences at the bottom of the tube and
gradually rises to the top after traversing the whole mass. This
compound Mr. Kemp considers to be an oxide of phosphorus.

I found that when carbon and dry pure boracic acid are
heated to redness in a porcelain tube, and pure iodine drop-
ped into it whilst at this high temperature, a small portion
of a yellow compound sublimed, which I considered as an
iodide of boron. * ¥ * ‘i

When solutions of the protonitrate of mercury and hydrio-
date of potassa are mixed together, the green protiodide of
mercury is precipitated; bat by this method a portion of the
yellow iodide is almost invariably found mixed along with the
green, on account of the presence of a portion of the perni-
trate. But this is completely obviated, and a very pure prot-
iodide formed, when the elements themselves are made to act
on each other. I found that on agitating together the iodine
with an excess of metallic mercury in a tube, that combination
was formed. After the action has commenced, the addition
of a little water facilitates its completion. This iodide, by the
combined influence of air and light, is resolved into metallic
mercury and the biniodide. ‘To try which of these agents had
the greater power, I placed a portion of the green iodide (being
perfectly dry) in a closed box impenetrable by any species of
light. On examining it in a few weeks afterwards, I found
that it was only partially decomposed, and those portions that
had undergone the change had assumed a very beautiful ap-
pearance. There was rising out of the mass at different
places a formation exactly similar to one
of vegetable origin: |. represents a small
mass of green iodide from which the
‘eryptogamic-looking excrescence sprung;
2. represents the root, which was of a red
crimson colour; and 8. is the upper expanded portion, which
on the exterior was covered with a feathery crystallization of
the yellow iodide. The interior was hollow, and was exter-
nally of the same rich red colour as its root. ‘These vegeta-
tions resembled much in richness and beauty the bells of some
of the finest heaths.

Another portion of the green iodide was placed in a small
phial filled with distilled water, which after being exposed to
the light for many weeks, still retained its original green co-
lour, being as yet undecomposed. Air, therefore, is the prin-

Third Series. Vol. 8. No. 43. Jan. 1836. D

1g Dr. Inglis’s Extracts from his Prize Essay on Iodine.

cipal agent in effecting its decomposition, since in both in-
stances the temperature was the same, and must have affected
each alike. As the bichloride of mercury added to a solution
of the hydriodate of potassa causes the formation of the bin-
iodide, it might be expected that the protochloride would give
us the green protiodide, which on trying I found to be the
case ; when equal parts of calomel and hydriodate of potassa
are added to each other (the one in solution and the other
suspended in water) an instant interchange takes place, and
the green iodide is produced. This took place in all cases,
whether I used the calomel in excess, or vice versd. But I
found that on pouring off the supernatant liquid from the
green iodide, in either of the above instances, and now adding
the calomel, the precipitation wholly consisted of the beau-
tiful bright yellow iodide; or, if to a solution of the nitrate
of mercury in excess, there be added the above-mentioned
liquid, there is instantly a flocculent precipitation of pure ses-
quiodide. From these facts I presume that in the process for
the production of the green iodide there is formed a sesqui-
chloride of mercury, 7.e. a chloride having one half more
chlorine in its composition than calomel = (2 Hg +3 Ch, or
1 Hg + 13Ch), and analogous to the sesquiodide. I men-
tioned before that the same results always followed whether
I used the calomel, or the hydriodate of potassa in excess.
The yellow sesquiodide of mercury may be kept for any
length of time excluded from the light without changing co-
lour; but if exposed it soon acquires a dark hue. By heat
one might suppose it had been converted into the biniodide,
for it assumes first a red hue, then by continuing the heat it
fuses and becomes of a deep crimson colour, and _volatilizes
into crystals of the same tint, but on cooling the original yel-
low is restored. It is singular enough that exactly an oppo-
site effect is produced by heat on the biniodide; it is converted
at 400° Fahrenheit into a deep blood-red-coloured fluid,
which volatilizing condenses on the sides of the tube into
yellow acicular crystals, which retain that colour for a consi-
derable time, unless suddenly cooled or agitated, when the
characteristic crimson tint of the biniodide again appears.
The biniodide falls as a rich red powder when solutions of
the bichloride of mercury and hydriodate of potassa are mixed
together, and in this form it is generally seen. I, however,
have procured it in pretty large crystalline cubes by the fol-
lowing process. I found that it was dissolved in great abund-
ance by a boiling solution of the hydriodate of zinc. I added
the powdered biniodide till no more could be taken up, and

Dr. Inglis’s Extracts from his Prize Essay on Iodine. 19

then placed this saturated solution under the exhausted re-
ceiver of an air-pump; in a short time the biniodide began to
be deposited, and svon they increased and assumed the form
of large regular cubes. The hydriodate of zinc that remained
was capable of dissolving a fresh quantity of biniodide, or of
redissolving that which was crystallized from it: the crystals
contain no zinc; they are acted on by chemical agents and
by heat just in the same manner as the precipitated biniodide,
and are quite distinct from the hydrargo-biniodide of zinc to
be mentioned hereafter. ‘The biniodide of mercury is sufh-
ciently soluble in an excess of the hydriodate of potassa, from
which there results on slow evaporation a yellow salt, which
I discovered many months ago, and called it the double hy-
driodate of the biniodide of mercury and potash, because
I found that whenever it was brought in contact with water,
instant decomposition took place, the water from its strong
affinity for hydriodic acid removed it, and the red biniodide
was precipitated. Bonsdorff, however, calls this compound the
hydrargo-biniodide of potassium. * * *

On mixing bichloride of mercury in powder to a saturated
solution of hydriodate of potassa, and agitating together, the
whole becomes nearly asolid red mass, and much heat is at
the same time generated. * * * This red iodide is formed by
many other processes, as when a solution of bicyanuret of
mercury is added to an alcoholic solution of iodine, in which
case it instantly precipitates.

When the yellow sesquiodide is kept for some time under
water, and exposed to light, very good small cubic crystals of
the red iodide are found covering the surface; but the method
I described above is the best one for obtaining it in its cry-
stalline form.

I have reason to think that there is another iodide of mer-
cury, of a blue colour; it is formed by freely exposing in an
open vessel the red iodide with an excess of metallic mercury.
In the course of three or four weeks the surface assumes a
decidedly blue tint. I have not as yet further examined this
compound. * i = ii * *

On examining the crystal of the iodide of lead with the aid of
the microscope, it is found to be a flat six-sided cry-
stal [prism?]. This, next to the tetrahedron, appears,
from what I have observed to be the most common
form of crystallization. * * *. I found that when, in-
stead of using just a neutralizing sufficiency of hydriodate of
potassa and acetate of lead, the hydriodate was added in excess,
there was thrown down a white soft powder and not the yellow

iodide. And by ammonia the yellow iodide is converted into
2

SS

ED)
“yd,
WG»
Mpeg
ifr

iiss

SS

y,
XZ

20 ~=©Mr. Henwood on the Steam-Engines of Cornwall.

a similar white powder, which, perhaps, may be another iodide
of lead. If metallic tin be boiled with the iodide of lead, no
reaction takes place; but if the dry iodide be mixed with gra-
nulated tin, and exposed to heat, combination takes place, and
a double iodine of tin and lead results, of a brown colour and
differing from either iodide separately. By boiling this double
iodide in water, very beautiful crystals of the yellow iodide of
lead are obtained. [To be continued.]

V. Observations on the Steam Engines of Cornwall; in Reply
to John Taylor, Esq., F.R.S., Treas. G.S., Sc. By
W. J. Henwoop, F.G.S. Lond. & Paris, Hon. M.Y.P.S.,
Curator of the Royal Geological Society of Cornwall.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

R. TAYLOR’s communication in your present month’s
Number* appears to imply that a rotatory single engine
working expansively is something of a novelty.

Now, Mr. Watt’s first expansion engine was erected in
1778+; the patent for his rotatory engine was taken out in
1781, October 25th ¢; and that for his double engine in 1782,
March 12th §.

Thus the rotatory single engine working expansively pre-
ceded the invention of the double engine; and some of the
former construction were erected by Messrs. Boulton and
Watt on the Cornish mines.

At Binner Downs mine in this county Messrs. Gregor and
Thomas have erected five rotatory single engines working ex-
pansively ; the first of them in 1828, the last in 1833. Captain
Gregor also set up a similar one, for driving a common grist
mill, for Messrs. Harvey and Co. of Hayle Foundry.

All these have performed their work extremely well; are
quite as manageable as double engines ; and, where they have
taken their place, have worked with much less coal. The
duty of those at Binner Downs, which are used as winding
(whim) engines, Captain Gregor estimates at about 15 millions
of pounds raised one foot, high by the use of each bushel of
coal consumed ||.

Mr. Taylor speaks of “the method of working high pres-
sure steam expansively, which we owe to Mr. Woolf.”

* Vol. vii. p. 369. + Farey on the Steam-Engine, p. 341.

t Ibid., p. 346. § Ibid., p. 350.

Captain Lean reports the duty of Mr. Sims’s engine at Charlestown

44, and not 60, millions, as stated by Mr. Taylor.
§ Lond. and Edinb. Phil. Mag., vol. vil. p. 369.

Dr. Hudson on an Error in Dr. Apjohn’s Formula, 21

Now, in former numbers of this Journal*, I have shown
that in 1811—1812, Captain Trevithick erected a single engine
at Huel Prosper mine, in which steam of above 40 pounds
pressure on the square inch was worked expansively. Mr. Farey
observest that Mr. Woolf came to reside in Cornwall about
the year 1813, and the “ first engines for pumping water from
the mines were set up by him in 1814;” but these, he adds, -
had two cylinders. I therefore repeat, that we do not owe
this practice to Mr. Woolf, but to Captain Trevithick. But it
has been already shown that this is only an extension of
Mr. Watt’s practice of 1778.

The advance in the duty of steam engines which has taken
place in this county within the seven years last past, is princi-
pally, if not entirely, due to Captain Grose; and is obtained
mainly by the application of substances which transmit heat
very slowly, to the surfaces of the portions of the apparatus
containing dense steam.

I remain, Gentlemen,
Yours, &c.

1, Morrab Place, Penzance, W. J. HEnNwoop.
November 28, 1835.

VI. Onan Error in Dr. Apjohn’s Formula for inferring the
Specific Heats of dry Gases. By H. Hupson, M.D.,
M.R.LA.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

BEG to point out a serious error in the formula given (in
p. 385 of your 7th volume) by Dr. Apjohn for ascertaining
the specific heats of gases by their action on the “ evaporation
thermometer.” I have shown (in your Journal for October
last, same vol., p. 257,) that (taking the density of air at 212°
under 30 pressure as unity) the density of the vapour of satura-

tion at 7° is = wept * 13°75, consequently (the weight of
*327958

a cubic inch of air at 212° under 30 being nti E t) the

weight of a cubic inch of the vapour of saturation at 2° i=

of Grs.

—/—_ x 327958 ; at of at t° be-
usa * 3°27958; also the latent heat of vapour at ¢° be

* Phil. Mag. and Annals, vol. vii. p. 323, March 1830, and vol. x. p. 98,
August 1831. + Ibid., vol. viii. p. 308.

f -327958 is the weight at 32° (Prout), and 1°375 the expansion be-
tween 32° and 212° (Gay-Lussac).

22 Dr. Hudson on an Error in Dr. Apjohn’s Formula.

ing = 1168—¢ (capacity of water being = 1), it follows that

1168—t eas Up NEA | oaths

ery x f x 327958 of water in falling 1° will give out
the quantity of heat necessary to produce this cubic inch of
vapour. But in the experiments with dry gases an equal
volume (i. e. one cubic inch) of the gas falling V° produces this
same effect; consequently (S being the weight of a cubic inch
of the gas at ¢°) VxS gives the weight of the gas which
would produce this effect in falling 1°; from whence it is
obvious that 1 (the capacity of water): C (the capacity of

1168—¢ 1168—¢
“ J; —____ 27 dO ae
the gas)::S x \ 748 Lt x f x 3°27958, and C 44840:
x a x 3:27958; or (since S’,the weight of a cubic inch of
S x 508 MALES
. fe} ( RSs
the gas at 60°, = ade we have by substitution
1168—t x f
Gy eS Se ° 456.
Vx’ x 006456

Now, if V (the depression of wet thermometer) in hydro-
gen gas be = 20° (/’, the temperature of wet ball being 48°),
and if V in atmospheric air be = 25° (¢ being = 43°), and

Gr.

taking weight of cubic inch of hydrogen at 60° = 0:02153,

Grs.
and weight of cubic inch of air at 60° = 0°3099*; conse-
quently,

1120 x 34875 _ ee
20 xc02153 © 006456 = 5°856,

, 2 A D185 % 99848). Wow hag
and capacity of air = STU a is 006456= 2751.

Dr. Apjohn appears to have used ( for every gas) the weight
of a cubic inch of air, instead of S, the weight of the particu-
lar gas. Accordingly, the experiments (except with hydrogen)
rather favour my view that the capacities of gases are equal
in equal volumes.

The same I believe to be true with hydrogen, and that
V will be found the same in every gas (with an improved
apparatus for trying the experiments) under similar circum-
stances of temperature and pressure, if the current of gas be
sufficiently powerful.

capacity of hydrogen =

* J have supposed P (the pressure) = 30. ‘The requisite alteration in
1168 —t x f

the value of S! gives C= —Vxsxp ™ 006456 x 30.

Prof. Powell’s Remarks on M. Melloni’s Paper. 23

Hoping for an immediate insertion of this, I shall reserve
any remarks on the probable errors in the experiments, and
their causes, for a future occasion.

I am, Gentlemen, yours, &c.

24, Stephen’s Green, Dublin, H. Hupson.
Nov. 11, 1835.

VII. Remarks on a Paper on the Transmission of Calorific
Rays, &c. by M. MEtont, in the Phil. Mag. and Journal
of Science, No. 42. By the Rev. B. Power, M.A., F.R.S.,
Savilian Professor of Geometry, Oxford.*

N the last Number of this Journal (vol. vii. p. 475) a short
communication appears from M. Melloni, in which that di-
stinguished experimenter has honoured me with a reference to
the experiment which I tried in 1825, which forms the basis of
a peculiar view of the nature of the heat originating from lu-
minous hot bodies, and which M. Melloni has since successfully
verified with his extremely delicate apparatus, so as entirely to
remove all doubt, which (I presume from the silence of phy-
sical writers) must previously have been felt on the subject.

But while he speaks with approbation of that experiment,
M. Melloni refers to my views connected with it in terms which
imply a most singular misconception of them, and on which
I therefore feel it necessary to offer a very few remarks.

M. Melloni describes me as “ endeavouring to explain his
results by hypotheses” which are untenable. Now, I am not
aware of having attempted to explain M. Melloni’s results at
all. All that I have contended for is, that if the distinction
between two kinds of heat, “luminous and obscure” (as the
author terms them), be admitted, (and he himself, I believe,
admits it,) it will follow, that all results which have hitherto
been commonly stated as referring to “ radiant heat,” will
require now to be more precisely worded, and we must say
which sort of radiant heat we mean, in all cases where there
may be both present.

That particular result which M. Melloni obtained in the
repetition of my experiment with the thermomultiplier, and
which so strongly confirms it, I have, indeed, adverted to as,
to my apprehension, ill explained by the gratuitous hypothesis,
that the heat acquires a new property with regard to its re-
lations to surfaces by merely passing through glass; which
seems to me at once needless and contrary to all analogy;

* Communicated by the Author.

24 Prof. Powell’s further Observations on M. Cauchy’s

and, instead of it, I have maintained the simple conclusion of
two kinds of heat simultaneously emanating or originating
from luminous hot bodies.

As to contending that this distinction of two kinds of heat
‘‘ suffices to explain all the facts relative to transmission,”
I should have been glad if M. Melloni had pointed out any
passage in which I have contended for anything of the kind.
The facts of transmission (and for all these most curious and
important facts we are entirely indebted to the experimental
skill of M. Melloni) are of a kind as yet appearing so little
reducible to fixed laws that I should imagine any theory en-
tirely premature; certainly I have offered none.

The experiment described by M. Melloni (p. 477 at the
bottom) is undoubtedly a most curious and interesting one,
but how it applies to the question relative to mine I fail in
perceiving. It proves, the author conceives, that there are in
this case ‘several different kinds of dark heat.” It is true we
have hitherto known of but one, and I have referred only to
one in my researches, but I have never denied that there may
be two, three, or a hundred kinds. I have merely maintained
that there are characteristic and well-marked distinctions in
the properties of any or all non-luminous heat (to adopt for
brevity the barbarously incorrect language which is becoming
current) from those of the luminous kind; but there may still
be many more such characteristic distinctions, and some such
M. Melloni seems to have established in this experiment.

I look with great interest to the further extension of this
curious inquiry on a point requiring the most careful exami-
nation; while I acknowledge that the thermomultiplier of
M. Melloni has opened to us an entirely new field of investi-
gation, and in the hands of its inventor and of Prof. Forbes
has done more for the advance of our knowledge in this de-
partment within a very short time past, than the most san-
guine would have ventured to anticipate.

VIII. Further Observations on M. Cauchy’s Theory of the Di-
spersion of Light. By the Rev. BapEN Powe 1, M.4A., F.R.S.,
Savilian Professor of Geometry, Ouford.*

N a former paper, which is inserted in successive portions of
this Journal, No. 31 e¢ seq. (vol. vi.), I have given an abstract
of M. Cauchy’s highly important researches on the undulatory
theory, so far as they bear on the great question of the disper-
sion of light, and in conclusion have deduced a simple for-

* Communicated by the Author: on this subject see also a preceding
article by Mr. Tovey.

Theory of the Dispersion of Light. . 25

mula expressing the relation between the length of a wave
and the velocity of its propagation. In a paper in the Phi-
losophical Transactions for 1835, Part L, I have exhibited the
results of calculation by means of this formula, by which theory
is compared with observation for all the cases determined by
M. Fraunhofer, and it will, I believe, be admitted that the ac-
cordance is as close as can be reasonably expected.

Since that paper was printed I have been indebted to Pro-
fessor Sir W. R. Hamilton for bringing to my notice the cir-
cumstance that the formula as there deduced, owing to certain
assumptions made in the course of the investigation, is not
absolutely rigorous, although under conditions which may be
easily admitted as likely to subsist it is reduced to the form
which I have used. ‘The state of the case will be rendered
evident from the following considerations.

In order to simplify the investigation M. Cauchy adopts
the method of supposing an expression, which really consists
of the sum of a series of analogous terms, reduced to a single
term; upon this he pursues his inferences with respect to it,
and then in the conclusion recurs to the summation again.
The complete resulting expression would represent the mo-
tions of an entire system, considered as produced by the com-
bination of many, or even an infinity of, similar motions, each
represented by the simplified equations obtained with the
omission of the sign of summation. This will be understood
on a comparison of those parts of my abstract which intro-
duce equations (21.) and (56.). On the same supposition
I have proceeded to that deduction which leads to the formula
expressing the relation between the length of a wave and the
refractive index. (See p. 265, Lond. and Edin. Phil. Mag.,
April 1835.) ;

The formula thus deduced, in its simplified shape, viz.

\- (2
at Lala sin

(9)
= ~

(eau

~

is obtained by collecting together into one constant (H/’) the
sum of a number of terms of analogous forms which com-
pose the values of the coefficients L, M, &c. Now if we recur
to the expressions from which these values were originally
derived, the equations (22.) and (12.), (or in the original
memoir, more explicitly, equation (20.),) we shall readily per-
ceive that the values of these coefficients in their exact form
(that is, retaining the sign of summation,) are such as these:
Third Series. Vol. 8. No. 43. Jan. 1836. E

26 Prof. Powell’s further Observations on M. Cauchy’s

L
= S {F (m, 1, «) « > (A, 7 cos) },
&c. = &e.

Whence we should derive

4s = s{ (F (m,7,«) + F (m,r, B) +, &c.).$ (kyr, cos) } 5

Hence by the same process as that employed before, we may
obtain a corresponding abridged expression

‘hee Tae ) x
(—) =8}@)(— Sx
e eG
2
To perceive more clearly the difference between the exact

and approximate expressions, we may first observe, that since
we have from equations (19.) and (45.)

k 7

ne and 7 cos 8 = Ag,

E Sei s Ao.
the arc which is involved in the formula becomes - el

Now, if we take the simplified formula, develope the sine
in terms of the arc, and divide by the arc, we shall have

Thee 1 ;Ag.ny? WR Ne oe ‘
eee ee easy |

whereas the exact formula, in the same way, would give

1 wate 1 S[(H") (M7) 7
aire. {1-2 = S(EE)
oe)
120 ee pRtee

supposing the series to converge rapidly enough.
Now, this would manifestly be the same as the last if we
were at liberty to suppose

spans (287)"] = psaay) [227],

and similarly in the other terms: in which case we should

Theory of the Dispersion of Light. 27

only have a common multiplier for the whole series, which
would be represented by H'. Now this supposition would be
the same as that of
S [(H®) (Ag)] = (S (HP) (Ag)
for the same value of A; or, since A g is the difference in per-
pendicular distance from a given plane, of the molecule at the
point vy = at the end of the time ¢, it will be evident, on a
little consideration, that to disregard the sign of summa-
tion altogether corresponds to taking into account only the
action of two adjacent molecules. If again we apply it
only to H* (as in owr simplified formula), without regarding
Ae as variable, this is equivalent to considering only the ac-
tion of two adjacent parallel strata of molecules, for all of
ae

which Ag isthe same. But if i) be small, and the series

A : : :
consequently converge rapidly, (=") being still of sensible

magnitude, we may suppose that this is not far from the truth.

I will not, however, say more with regard to the analysis
of the theory at present, as the subject has been taken up by
Sir W. R. Hamilton, with whose researches Gn systems of
rays, in fact, the other parts of M. Cauchy’s investigations
are closely connected. My abstract has been restricted to so
much of those investigations as refers directly to the subject
of the dispersion; but the entire theory, of which it forms a
part, embraces the curious and beautiful discussion of wave
surfaces: and the connexion and analogy of some of the most
important of these results with his own researches are speci-
ficially pointed out by the Irish Astronomer Royal in his third
Supplement to the Theory of Systems of Rays in the Trans-
actions of the Royal Irish Academy, vol. xvii. p. 125 and 141.
Since this paper went to the press, that eminent mathematician
has kindly given me permission to make what use I please of
some further investigations on the subject of the dispersion-
formula, including its numerical applications, which he had
communicated to me. I hope, therefore, in a subsequent
Number of this Journal to give some account of these im-
portant researches,

The development of the value of fe) in a series of powers
of A, in a form available for the actual comparison of theory
with observation, vy the use of a peculiar method for determin-
ing the coefficients, appears also to have been lately investigated
by M. Cauchy. His “ Eercices de Mathématique,” which,
as | stated in a former paper, were broken off abruptly in 1830,
have now been resumed, and are in the course of publication

EK 2

98 Mr. Rose’s Sketch of the Geology of West Norfolk.

at Prague, under the title of “Nouveaux Exercices,” &c. They
will contain the continuation of the theory of dispersion, and
the development in a form adapted to calculation. The di-
stinguished author also has recently produced a memoir on
interpolation, by a new method, which in conclusion he
briefly applies (but without sufficient explanation) to the cal-
culation of the refractive indices, in one instance of flint glass
from Fraunhofer.

One thing, however, is clear, viz. that from the close accord-
ance between all the results which I have calculated (by the
approximate formula) and those of observation, viz. the ten
sets of indices obtained by Fraunhofer, and since that, ten
other sets determined by M. Rudberg (very recently com-
municated to the Royal Society*), it is sufficiently evident that
at least for all these cases the approximate supposition is as
near the truth as, perhaps, will be thought sufficient, when
all circumstances are considered.

It is, however, still quite conceivable that the differences,
minute as they are, may be accounted for by a more accurate
prosecution of the analysis. Again, it remains to be seen
whether in other cases, especially those of more highly di-
spersive media, the same method will still apply, or whether
we must have recourse to a more complex investigation, which
shall yet include, as a simplified case, the formula which holds
good for media of low dispersive power.

= +

1X. A Sketch of the Geology of West Norfolk. By C. B. Rose,
Fellow of the Royal Medical and Chirurgical Society of Lon-
don.

(Continued from vol. vii. p. 376, and concluded. }

Diluvium.— CiLsy, sand, or gravel of varying thickness, and

frequently alternating beds of these substances,
are found immediately incumbent on the chalk, and obscure in
many places its outcrop, as they also do that of the gawlz, lower
greensand, and clays of Marshland+. These irregular beds,
alternating with each other, without any order of superposition,
have received the name of diluvium ; but itis so difficult to de-
termine what has been deposited by diluvial agency, in other

* So long ago as 1827 we received and inserted in Phil. Mag. and
Annals, N.S., vol. ii. p. 401, a paper on the undulatory theory of disper-
sion from M. Rudberg. Has this been lost sight of in the recent investi-
gations of the subject ? Some of the calculated numerical results obtained
by M. Rudberg, we observe, are identical with those obtained by Professor
Powell, as given in Phil. Trans, 1835, pp. 252, 254.—Epir.

+ The diluvium in Marshland is covered by a considerable thickness of
alluvial deposits.

Mr. Rose’s Sketch of the Geology of West Norfolk. 29

words, by the mighty debacle, and what was deposited by the
usual currents found in large basins of water, into which huge
rivers emptied themselves, that, with our present knowledge,
in My opinion, we cannot apportion the effects due to each
agent. ‘That the clays, particularly, are composed of trans-
ported materials there cannot be a question, for the chalk
which forms the substratum of the greater part of western
and central Norfolk could not furnish the blue clay so fre-
quently met with upon it: not only this, the boulders, so
abundantly found in the clay, inclose organic remains
which enable us to determine that their parent rocks are si-
tuated fifty, nay hundreds of miles apart from them. With-
out noticing the fragments of primitive rocks (which are more
difficult to identify, in consequence of their not containing
organic remains), I may particularize boulders from the old
red sandstone, mountain limestone, alum-shale of Whitby, blue
lias, cornbrash limestone, Septaria of the Oxford and Kimme-
ridge clays, &c., all inclosing animal exuvize that indubitably
determine from what strata they were disrupted. As many of
these boulders weigh some hundreds of pounds, indeed, some
tons*, it is fair to infer that no common current or torrent
could have impelled them to their present sites, making every
allowance for time; indeed, the magnitude of some of them,
the distance they must have travelled, and the want of order
in the arrangement of the clay, sand, and gravel, all combine
to render it highly probable that the transport of these ma-
terials could not have been effected by any other agent than
the Noachian Deluge.

The light lands covering the outcrop of the chalk abound
in bleached fragments of flint, the debris of the abraded chalk;
these fragments are in many places (as around Castleacre) so
abundant, that it is found necessary to pick them from the
and about once in four years, to the amount sometimes of
two loads (24 bushels to the load) per acre. The clay of the
heavy \ands is either yellow or blue: the former contains a
large proportion of calcareous matter, and in it large fractured
flints predominate, with their angles sharp; the blue clay is in
a much greater degree argillaceous, and is also remarkable
for the abundance of boulders of the oolitic series of rocks,
having all their angles rounded. The gravel beds are prin-
cipally composed of fragments (in the form of pebbles) of al-
most every member of the series of rocks, from granite up-
wards, with every angle effaced, manifestly the result of long
exposure to attrition, ;

In some situations, as is exemplified on Necton Common

* A boulder of breccia in a clay-pit at Fouldon, south of Swaffham,
weighs several tons.

30 Mr. Rose’s Sketch of the Geology of West Norfolk.

near Swaffham, the gravel beds contain so large a quantity
of decomposing iron pyrites, that the water percolating the
gravel is sufficiently charged with iron to cement the sand
and stony fragments together, and form a coarse breccia.
Under similar circumstances, the water of some springs has
a considerable ferruginous impregnation : at Thetford a chaly-
beate spring occurs, containing also carbonate of soda and
free carbonic acid, with a proportion of zvon not inferior to
that of Tunbridge Wells, although it flows from a very dif-
ferent source; the elaboratory of ow chalybeate being situated
in the diluvial beds, and the decomposition of iron pyrites
from the disrupted chalk strata affording the ferruginous in-
gredient.

Fragments of calcareous tufa are occasionally met with in
these beds. i

Being desirous of not extending this paper beyond the li-
mits of a periodical, I forbear noticing the ceconomical and
agricultural purposes to which these beds are applied; and
for the same reason I shall refer your readers to Mr. Samuel
Woodward’s Geology of Norfolk* for a list of the antedilu-
vian organic remains, which are, for the most part, inclosed
in boulders.

The only mammalian remains I have seen are, part of a
tusk of Elephas primigenius found at Hunstanton, teeth and
vertebrae of Elephas Indicus from beneath the brick-earth at
Narford, and part of a tooth of the Mastodon latidens? found
in a gravel-pit at Swaffham.

It is worthy of notice, that the parent strata from which
the boulders must have been originally detached are all si-
tuated to the north and the west of our county.

Alluvium. —The first deposit I shall notice under this head
has received the name of * Brick-earth of the Nar,” from my
having (till very recently) found it only in the valley through
which that river takes its course. In this valley I have traced
it west and east from Watlington through East Winch and
West Bilney to Narford, a distance of nine miles. It occupies
low grou d, except at its inland extremity, where it rises to
about eig"ty feet above the level of the Nar.

Mr. Arthur Young in his “ Agricultural Survey of Nor-
folk,” speaking of this deposit, under the article “* Manure
Oyster Shells,” says, “In East Winch and West Bilney, and
scattered for ten miles to Wallington (Watlington ?), there is
a remarkable bed of oyster-shells in sea mud: the farmers use
them at the rate of ten loads an acre for turnips, which are a
very good dressing; they are of particular efficacy on land

* An Outline of the Geology of Norfolk, page 39, “ Clay of Western
Norfolk,”

Mr. Rose’s Sketch of the Geology of West Norfolk. 31

worn out by corn. * * * * * ‘They are found within two
feet of the surface, and as deep as they have dug, water having
stopped them at sixteen or eighteen feet deep. They fall into
powder on being stirred.”

The clay inclosing the shells is of a slate blue colour, and
upon drying falls into laminz ; it contains numerous spangles
of mica, and in the lower part of the bed at Winch and Bil-
ney there is a considerable admixture of sand. It has a very
muddy smell when first opened, and the water which rises
from it is too offensive to be used for culinary purposes. No
boulders have been found in it.

At West Bilney it is generally covered by two or more
feet of earth, consisting of vegetable soil, and yellow sandy
loam, containing small pebbles and angular fragments of flint.
The yellow loam burns into a red brick; a portion lying be-
tween the loam and the blue clay, and probably a mixture of
the two, produces a mottled brick; and the blue clay, usually
denominated the brick-earth, becomes a fine white brick. At
another part of the brick-yard bleached shells, chiefly Turri-
tella Terebra and Mactra subtruncata, are found immediately
beneath the vegetable soil in white sand: the same shells are
also scattered through the brick-earth, with Ostrea edulis, Ros-
tellaria Pes Pelecani, &c. At this locality a well was sunk
to the depth of forty feet, and Ostree and Rostellarie were still
brought up; but the oysters were most abundant at the depth
of three or four feet from the surface. ‘Two fragments of the
grinding teeth of the Oz, and small portions of bone, were
also found in the blue clay, at the depth of five feet.

At East Walton, Ostree, Turbo littoreus, and fragments of
a Pecten are turned up by the plough; in a pit they may also
be seen imbedded in a light-coloured alluvial clay, rising
abruptly from the valley of the Nar to the height of eighty
feet above the level of the river: the shells are much more
broken than those found in the blue clay, situated at a lower
level ; indeed, in the latter situation but few are at all injured.
At Walton Stocks the same shells were also found.

At Narford, near the Hall, in the same fetid blue clay as at
Bilney, Ostrea, accompanied by Rostellaria, were discovered
beneath a considerable bed of sand and loam; the clay was
sunk through at the depth of twenty-seven feet, and in its
lowest portion teeth and vertebree of the Asiatic Elephant
were found: this is the most inland extremity of this deposit
at present detected. The shells of the same deposit have also
been found at a brick-yard in East Winch, covered by seven
feet of sand and loam: beneath these lie a light-coloured ar-
gillaceous earth, six feet in thickness, containing a few shells,
which reposes upon the blue clay, in which the Ostree, Ros-

$2 Mr. Rose’s Sketch of the Geology of West Norfolk.

tellarie, &c. are very abundant; the blue clay has here been
opened to the depth of ten feet. Very recently have been dis-
covered at this spot, in the loam, fragments of a tooth and
bones of an elephant, and a broken tooth of a rhinoceros.

In the middle of the village of East Winch, by the side of
the road leading to Lynn, Ostree and Rostellarie were dis-
covered on sinking a well; and on Mr. Forster’s farm, in the
same parish, similar shells were found.

At Tottenhill brick-yard, a short distance from the road
leading from Lynn to Downham, and at Watlington, the
same bed of blue clay is met with, inclosing similar shells to
those at West Bilney.

The same kind of blue clay was opened last summer about.
half a mile to the south of Middleton ‘Tower, in a valley run-
ning parallel to that of the Nar, and separated from it by the
high ground on which the village of Middleton stands; a small
stream takes its course through this valley, emptying itself, as
the Nar does, into the Ouse at Lynn. Ostrea edulis and
Turbo littoreus were found six feet below the surface.

In some localities, with the Ostree have been found Cardia,
Mactra, and other shells, of which the following is a list. The
greater number of the oysters are large, thick, and antiquated ;
they and the Rostellarie are very abundant; Natica glaucina
is next in abundance; Pecten and Cerithium are scarce. The
shells have not suffered by attrition, but few are broken, and
none of them are mineralized.

Organic Remains.

Name. Reference. Locality.

Vermilia triquetra ...... Brown’s lllust., pl. 2.f.1,5. [On Ostrez, W. Bilney.
Cardium echinatum ...) —————-—_ pl. 21. East Winch.

STEGIUC .sseeasteaee Wood’s Conch., pl. 55. f. 4.) Ditto. Ditto.
Corbula Nucleus ......... Brown’s Illust., pl. 14. f.6,9.| W. Bilney.
Mactra subtruncata......) —————-— _ pl. 15. f. 7. Ditto. E. Winch.

SOLIdA; 05s o0deee Penn. Brit. Zool., pl.55.f.2.| Ditto.
Ostrea edulis ............ Brewn’s Illust., pl. 31. f.19.) Do. Narford, &c.
Pecten varius ... a tr eae Zo0k la Do. Walton.
Tellina,young specimens), species undetermined. W. Bilney.
Cerithium reticulatum | Geol. Norf., t.1. f. 2. W. Bilney.

Turritella Terebra ...

—_—

Buccinun: reticulatum

Brown’s Illust., pl. 51. f. 56.
Min. Conch., t. 565. f. 3.
Penn. Brit. Zool., pl. 75. f. 2.

} Do. _E. Winch.
Ditto.

Turbo littoreus ......... Brown’s Illust., pl. 46 f.1,9.| Do. Do. Walton.
Rostellaria Pes Pele- | | Penn.Brit.Zool.vol.iii.pl.78. D Do.. &
ee eas } Sow. Min. Con., t. 558. f. 1. } tae Rae
Natica glaucina ......... Brown’s Illust., pl. 43. Do. Do.
BIOS; TCCEDION, .cichs «steven ee ea cain ia an Ditto.
Elephas Indicus, teeth and vertebrz of. Narford. E. Winch.
Rhinoceros, fragments of a molar tooth of the lower \E Winch
MAW Tithe teas ly be atte os or anebrewserse cheeks. tle ; 3

* Dr. Buckland’s Reliquie Diluviane, pl. 7. fig. 6.

Mr. Rose’s Sketch of the Geology of West Norfolk. 38

We have here shown, that within the valley of the Nar
there occurs an extensive deposit of mud, containing marine
shells, the living congeners of which inhabit the adjoining sea.
The accompanying map (vol. vii. Plate I.) of the ground oc-
cupied by this deposit is a portion copied from the Ordnance
map, and exhibits the high grounds bounding the valleys. I
have affixed the various localities where the shells have been
found, to render my account more intelligible, and to show the
extent and course of the deposit. The shells have at present
been found on the north side of the valley only, except at
Tottenhill and Watlington; they have not been met with on
the south side (the present course of the Nar) beyond Wor-
megay, but occupy the low ground to the north and east of the
elevated patch of carstone on which Bilney Lodge stands, and
are-again found in the valley of the Nar at Narford.

The general level of that portion of the brick-earth in which
the oyster-shells are most congregated is not much above
low-water mark at Lynn; at the Bilney brick-yard they are
about seventeen feet above it. ‘Their elevation to the extreme
height (about 100 feet) at which they are found at East Walton
was probably effected by spring tides in conjunction with storms
casting them upon the shore of the creek (presuming this
valley to have been once a creek of a sea): the fractured
state of the shells and the high angle of their elevation at
this locality will, I conceive, justify such an inference; indeed,
the equinoctial gales, which here blow with great violence from
the west, and consequently cowards Walton, would impel waves
with corresponding force up this very acclivity.

We are therefore led to infer that this valley was, at a re-
mote period, occupied by the waters of the ocean: upon ex-
amining the accompanying map, and observing the relative si-
tuations of it and the estuary called the Wash, it will be seen
that the embouchure of the former is in the direction of the
latter; and when we bear in mind that there is a process of
filling up constantly in progress in all estuaries, and that our
estuary, therefore, must once have extended much higher into
Marshland, we cannot doubt that the valley of the Nar ata
former period opened directly into the estuary, and that the
ocean’s waves flowed freely into the valley, forming an ex-
tensive creek, bounded by the high grounds of North Runc-
ton, Middleton, and East Winch on the north; those of Wal-
ton, Westacre, and Narford on the east; and of Marham,
Shouldham, and Tottenhill on the south.

I think it not at all improbable that similar deposits of
mud and shells to those of the Nar and Middleton Tower
may hereafter be discovered in the valleys of South Wooton

Third Series. Vol. 8. No. 43. Jan. 1836. F

34 Mr. Rose’s Sketch of the Geology of West Norfolk.

and Castle Rising; indeed, on the road leading from Lynn
to Hunstanton, there are many visible indications of a resi-
dence of the sea upon lands now raised to an elevation be-
yond the reach of the highest tides. At Dersingham Heath
and at Ingoldisthorpe it is not difficult to trace at various
points terraces parallel to the shore of the Wash, raised by
the waves of the flowing tide, and troughs and gulleys formed:
by the retiring waters of ebb tide. ‘The adjoining marshes
are considerably below the level of high tide, and are pro-
tected from inundation by embankments.

It is probable that the elevation of the strata at Hunstan-
ton Cliff (rising about fifteen yards in a mile), continued along
the eastern shore of the Wash, mainly contributed to the ex-
clusion of the salt water from the valley of the Nar, and that
it was further reclaimed by the silting up of the upper part of
the estuary, and the embankments constructed by man.

As this brick-carth is nowhere covered by transported ma-
terials inclosing boulders of distant strata, we must consider
it to be a post-diluvian deposit*.

Ancient Beach.—At Hunstanton, manifestations of a great
change in the relative level of the sea and the present cliff
exist. I paid a visit to this interesting spot last summer, and
whilst examining the greensand stratum at a part considerably
beyond the point where the incumbent red chalk crops out
(the least attractive portion of the cliff), I discovered traces of
an ancient beach composed of rounded fragments of red and
white chalk, immediately reposing upon the greensand, and
covered by 93-feet of sandy loam, containing small angular
fragments of flint. ‘The weather came on so stormy and wet,
which continued during my stay, that I could not then carry
further my examination. At the spot I examined, the old

* The following are references to deposits of the same epoch: ‘‘Recent
shells resting on the out-goings of the floetz strata in Clackmananshire,” as
stated by Mr. Bald, in Mem.Werner. Soc., vol. i. p. 403;—‘ Marine shells
found in the line of the Ardrossan canal,” by Capt. Laskey, Mem. Wern.
Soc., vol. iv. part li. p. 568;—‘* Marine shells of existing species on the left
bank of the Mersey, and above the level of high-water mark,” discovered
by J.'lrimmer, Esq.; vide Proceedings of Geol. Society of London, vol. i.
p. 419;—the occurrence of similarly situated shells near Preston in Lan-
cashire, as stated by Mr. Gilbertscn, and confirmed by R. I. Murchison,
Esq., who likewise observed “ similar phenomena over a very considerable
tract of country occupying the ancient estuary of the Ribble;” vide Pro-
ceedings Geol. Soc. Lond., vol. i. p. 365, 366.; [also Phil. Mag. and An-
nals, N.S., vol. xi. p. 366.—Enrv. ] ;—and “ Description of a bed of recent
marine shells near Elie on the southern coast of Fifeshire, by W. J. Hamil-
ton, Esq., Sec. Geol. Soc., read March 11, 1835. [Lond. and Edinb, Phil.
Mag., vol. vii. p. 318.] In imitation of the technical language of Mr.
Lyell, the period of these deposits may be termed the pascene, from ras
omnis, and xesvoc recens, all the shells being of recent species.

Mr. Rose’s Sketch of the Geology of West Norfolk. 35

beach is immediately incumbent on the breccia of the green-
sand, five feet above the level of the present beach, and rises
towards the east from Lynn bay ; consequently it inclines in
an opposite direction to the regular strata. I purpose taking
the earliest opportunity of prosecuting my research into this in-
teresting relic of * olden time,” to trace its course and extent,
and particularly to explore it for testaceous exuviz ; at present
none have been seen. Mr. E. Mugridge, at my request, has
endeavoured to trace the course of the old beach, and thinks
it rises to the surface at a part of the cliff which is about 40
feet high.

Alluvium of Marshland.—Marshland is part of the Bedford
Level, forms the western boundary of this county, and con-
tains about 63,000 acres of low-Jand. It is geologically com-
posed of alternating beds of lacustrine silt and peat (covering,
in the immediate vicinity of Lynn, a marine silt), lying upon
a stiff clay inclosing small nodules of chalk, the whole re-
posing on the Oxford clay.

The various canals and dikes cut for inland navigation and
for the drainage of the Level have exposed the beds above
mentioned. ‘lhe following are the sectzons I have been able to
procure. At Salter’s Lode, near Downham, “ the silt was
observed to be ten feet deep; and next below that, three feet
thicknesse of firm moor; then bluish gault, which the work-
men judged to have been silt originally, because being dry, it
not only crumbled, like it, but had the roots of reeds in it;
then below it moor of three feet thicknesse, much firmer and
clearer than the other; and lastly, whitish clay, which is sup-
posed to have been the very natural and bottome soyle at the
first, before those changes happened, either from the altera-
tion of the course of the sea, or choaking up of these out-
falls” * .

In making the Eau-brink Cut near Lynn the beds were
found arranged in the following manner:

1. Vegetable soil, and brown clay with sand... ... 4 ft.
2. Blue clay, a brick-earth =... 2. ee nee wee 8
3. Peat, containing bones and horns of ru- othe
vi) SE I eee eer Sa Sea } 0%
Blue clay, similar to No.2. ... 0 20. see eee ae 8
. Peat, with alder and hazel bushes; the lower seth, 3
tion clay, containing roots of marsh plants ...
. Dark blue clay, a marine silt, containing the fol-
lowing shells in great abundance: Cardium edule,
Mytilus edulis, Tellina solidula, Lutraria com-

*

nn

for)

* Dugdale on Embanking, &c. Edit. 1662, page 178.

I 2

36 Mr. Rose’s Sketch of the Geology of West Norfolk.

pressa, and Turbo ulve; this bed was not cut
through*.

In the beds Nos. 2 and 4, fluviatile shells were found: the
smaller ones appear to have been overlooked by the labourers,
but Anodons were noticed, and were found interspersed
throughout both beds; in No. 2. they were abundant, forming
a layer immediately upon the peat, No. 3.

The shells from No. 6. are certainly not of the same era
as those of the brick-earth of the Nar; they are evidently of a
more recent date, and resemble those now existing in the
river at Lynn.

At Mr. Allen’s well, in the town of Lynn, similar alluvial
strata to those at Eau-brink were met with, and were imme-
diately succeeded by a bed of blue clay containing nodules of
chalk, between 20 and 30 feet in thickness, which we consider
to be diluvium.

For the section of the alluvium at Denver Sluice see a former
part of this paper, vol. vii. p.173. By the above sections we
are informed of, and are enabled to arrange, the succession of
changes to which Marshland has been exposed. Commencing
with the period of the irruption of the sea, and its residence
in Marshland, during which the marine exuvie discovered in
making the Eau-brink Cut were deposited, we learn next that
this district became a marsh, in which alders, hazels, and marsh
plants vegetated. Its next change was inundation by fresh wa-
ter, forming a lake inhabited by freshwater Testacea, a transi-
tion probably effected by obstruction to the outlet of the rivers
of the great level, from bars thrown up by the tidal waves in
the estuary now called the Wash; this state continued till the
deposition of eight feet of mud had elevated its surface, and,
with the aid of other natural forces, burst its barrier; again the
waters escaped, leaving, perhaps, but a solitary river to drain
the interior ; again aquatic plants took possession of the surface,
and from the occurrence of large trees in the peat (No. 3.),
forests of oak and other trees indigenous to this island sprang
up, encompassed by brush-wood of hazel, alder, &c. This
was the state of the fens at the period of the Roman invasion;
and after the invaders had established their authority in the
country, they commenced embanking this district, to protect
it from the inroads of the sea }: itis said, that the Emperor Se-

* Marine silt containing similar shells occurs in Lewes Levels. (Dr. Man-
tell’s Geology, &c.)

+ Tacitas, in his life cf Agricola, says, “ the Britons complained that
their hands and bodies were worn out and consumed by the Romans, in ~
clearing the woods, and embanking the fens.”

Mr. Rose’s Sketch of the Geology of West Norfolk. 37

verus was the first to intersect the fens with causeways*. From
the time that the Romans finally renounced the sovereignty
of Britain, in the year 427, to the reign of Charles I., 1630,
(when the drainage of the Jevel was projected by, and com-
menced under the auspices of, the Earl of Bedford, being com-
pleted by his son in 1653,) a period of 1203 years, its cultiva-
tion was neglected, and it became a second time extensively
inundated, its forests laid prostrate, and in process of time
buried beneath lacustrine silt (No. 2, Kau-brink section); again
the rivers flowed in natural channels +, and ultimately this
morass, through the enterprise and skill of man, is reclaimed,
and the Bedford Level emerges a fertile tract of country.
The coin of Charles II. and the pair of scissors met with in
the excavation at Denver Sluice (vol. vii. page 173.) must have
been found at a spot that had been previously opened, for
the bed of peat No. 4. could not have been formed at so late
a period.

Many smal] formations of peat and deposits of silt are
found on the margins of the rivulets, and in the small basins
occurring on the surface of the dzlwvium; these contain the
shells of existing amd indigenous species of fluviatile Testacea.
Horns and bones of a species of elk, stag, and other mam-
malia are found imbedded in the peat.

Submarine Forest.—We possess but little information re-
specting the submarine forest off the coast of Norfolk.

« A forest seems to have extended from the coast of Lin-
colnshire a considerable way along the Norfolk coast, as there
is on the shore near Thornham, at low water, the appearance
of a large forest having been at some period interred and
swallowed up by the waves. Stools of numerous large timber
trees, and many trunks are to be seen, but so rotten, that they
may be penetrated by a spade. ‘These lie in a black mass
of vegetable fibres, consisting of decayed branches, leaves,
rushes, flags, &c.t Also, off Hunstanton and Brancaster, at
ebb tide, a bank of mud inclosing trunks and branches of

* Dugdale mentions one, “supposed to have been made by him of 24
miles in length, extending from Denver to Peterborough ; this was com-
posed of gravel about three feet in depth, and sixty feet broad ; it was dis-
covered beneath a covering of moor from three to five feet in thickness.”
Other works of art have also been found beneath the moor at various
places in the great level.

+ “In the year 870, the Danes (then Pagans) led by Inguar and Ubba,
made an incursion into this realm, and destroyed it (the religious house
at Ely): for such was the depth of the waters, which compassing this isle
extended to the sea, that they had an easy access unto it by shipping.’—
Dugdale, Edit. 1772, page 181.

{ Philosophical Transactions, No. 481, and Beauties of England and
Wales, vol. xi. p. 94.

38 Mr. Rose’s Sketch of the Geology of West Norfolk.

trees is seen. Mr. S. Woodward notices the above forest
under the head of ** Lacustrine formations,” and says, ‘ ‘The
ligneous deposit on Brancaster beach comes under this head,
and deserves our particular notice. In_this locality, trunks
of trees are found abundantly imbedded in the mud; and at
low water, the proprietors of the land thereabouts remove
them by means of a team of horses, and convert them into
posts and fences, or use them for similar purposes; the wood
being quite sound, and not in the least impregnated by
the soil in which they have been imbedded. With these are
found the horns and bones of the deer and ox, in excellent
preservation* .”

Mr. R. C. Taylor, speaking of the subterranean forest, says,
** Doubtless this must be the southern extremity of that sub-
marine forest which has long engaged the notice of geologists,
on the north-west part of Norfolk, whence it is traced across
the Wash and the fens of Cambridgeshire to Peterborough,
and all along the Lincolnshire coast, as far as the Humber.
There is no important variation in the general level of this
woody tract. As relates to the Norfolk portion, it appears so
closely in connexion with the crag formation, as almost to
form a part of it: the shells of the one being occasionally
mixed with the vegetable matter of the other ; and are further
accompanied by bones of stags, elephants, and oxen +.” Mr.
Taylor writes thus of its situation near Cromer: “ It is not
possible to say how far inland this subterranean forest ex-
tends, but that it is not a mere external belt is obvious from
the constant exposure and removal of new portions, at the
base of the cliffs ;” and again, “ near Cromer, the trees are a
few feet above the crag stratum, and are about the level of
high water.” He also believes it to have been antediluvian,
as we learn from the following reference to Dr. Alderson’s
** Geological Observations on the Vicinity of Hull and Be-
verly ¢.” ‘Dr. Alderson in describing the geological charac-
ters of that district (Holderness), many years ago, was of opi-
nion that the diluvial hills were heaped upon the submarine
forest. Nothing has arisen to discourage that idea; but it
derives confirmation from the parallel case which is presented
by the cliffs of Norfolk §.”

Professor Lyell (evidently in reference to Mr. Taylor’s
observations) expresses himself thus: ‘* After examining in
1829, the so-called submarine forest of Happisborough in

* Outline of the Geology of Norfolk, p. 13.

+ Phil. Mag. and Annals, N.S., vol. i. p. 289.

t Nicholson’s Philosophical Journal, 4to, vol. iii.
6 Phil. Mag. and Annals, N.S., vol,.i. p. 289.

Mr. Rose’s Sketch of the Geology of West Norfolk. 39

Norfolk, I found that it was nothing more than a tertiary lig-
nite of the ‘ crag’ period ; which becomes exposed in ihe bed
of the sea as soon as the waves sweep away the superincum-
bent strata of bluish clay*.”

Mr. Bakewell makes the following remarks: “ But these
subterranean forests in England deserve more attention than
thev have hitherto received from geologists; the period of
their growth, and the causes by which they were submerged,
are at present unknown. A similar subterranean forest ex-
tends into the sea on the coast of Flanders. Have these forests
been once united, and afterwards separated by a subsidence,
which formed the bed of the German Ocean +?”

Dr. Alderson and Mr. Taylor appear to have considered
these forests to have been antediluvian: I am not sure that
I understand Professor Lyell on this subject; his Jignite, I am
aware, is antediluvian, but in it, does he include “ large stools
of trees, their stems, and branches” ? If the subterranean and
submarine forests of the eastern coast be antediluvian, the sub-
terranean forests of Marshland are not contemporaneous to
them, but of a more recent period, for they, with the beds of
peat, are invariably found above what is considered diluvial
debris.

On the date of this “once sylvan tract” I ought not to
venture an opinion, for I have no personal acquaintance with
it, never having had an opportunity of examining the spot;
indeed, itis very difficult of access; and until it is determined
upon what substratum the “ mud inclosing the vegetable mat-
ter” is deposited, we cannot assign to the submarine forests
their place in the scale of formations: still, I cannot consider
this submarine forest (from the data connected with it already
collected) to be contemporaneous with the lignite of the crag
exposed in the cliff at Cromer, but believe it to be of the
same epoch as the subterranean forest of the fens, and that its
submergence was the result of the subsidence which formed
the trough for the German Ocean.

Recent writers evidently consider the subterranean forests
to be postdiluvian: thus, Phillips writes, “ All the lacustrine
deposits containing peat, which I have inspected in Holder-
ness, agree in this general fact, that the peat does not rest im-
mediately upon the diluvial formation beneath, but is sepa-
rated from it by at least one layer of sediment, which is seldom
without shells + .”

* Principles of Geology, by C. Lyell, Esq., second edition, vol. ii. p. 273.

+ Bakewell’s Geology, 3rd edit. p. 513.

t Ulustrations of the Geology of Yorkshire, by J. Phillips, Esq., p. 55.
[See also Phil. Mag. and Annals, N,S,, vol, ix. p. 353,—Ebir. |

40 .Mr. Rose’s Sketch of the Geology of West Norfolk.

Again: “The extensive accumulations of peat and trees,
along the shores of the Humber and its tributary rivers, hap-
pened, probably, at the same period of time as those which
have contributed to fill up the ancient lakes of Holderness.
This is inferred, with the highest probability of truth, from
the position of the peat with respect to the diluvial clay and
pebbles; for wherever these occur together, the former is in-
variably uppermost * .”

Dr. Fleming, describing a submarine forest in the Frith of
Forth, tells us the peat reposes upon a lacustrine silt; and
from the tenour of his remarks he evidently considers it to
belong to the “ modern epoch +”.

My observations on the alluvial phsenomena are brief, in
consideration of the great length to which my communication
had already extended. For much valuable information on the
subject I refer those who feel an interest in the inquiry to
two essays by the Rev. Dr. Fleming, published in the ‘Trans-
actions of the Royal Society of Edinbugh, vol. ix. p. 419, and
in the Quarterly Journal of Science, 1830, vol. vii. p. 21; and
to Mr. R. C. Taylor’s communication to a former volume of
this Magazine, entitled “ On the Natural Embankments
formed against the German Ocean on the Norfolk and Suf-
folk Coast, and the Silting up of some of its Astuaries* ”,—
papers replete with instructive matter.

Waving further speculation on the causes of the muta-
tions to which the small area that I have examined has been
subjected, I have in conclusion merely to state that in thus
arranging and publishing my geological notes I have but re-
sponded to an appeal made by Dr. Fitton, from the chair of
the Geological Society at the Annual General Meeting of the
Fellows in 1828, in the following words: ‘ But those who are
deprived of the privilege of travelling even in England, must
not suppose that they can be of no service as geologists ; or
if they belong to our body, that they are thus released from
their obligation to be active in our cause: and there are two
descriptions of persons,—the resident clergy, and members of
the medical profession in the country,—to whom what I am
about to say may be more particularly deserving of attention.
Such persons, if they have not yet acquired a taste for natural
science, can hardly conceive the interest which the face of the
country in their vicinity would gain, however unpromising it
may appear, by their having such inquiries before them; how
much the monotony of life in a remote or thinly inhabited

* Illust. Geology of Yorkshire, p. 56.

+ Quarterly Journal of Science, vol. vii. 1830, p. 21.
t Phil. Mae. and Annals, N.S., vol. ii. p. 295.

Mr. Rose’s Sketch of the Geology of West Norfolk. 41

district would thus be relieved, nor how much benefit they
might confer on the natural history of their country*.”
Swaffham, May 5, 1835.

Explanation of the Sections and Map.

The sections do not give the relative proportions or true
dip of the respective strata, but merely their order of super-
position.

Section at Hunstanton Cliff: Thickness.
No. 1. Vegetable soil and diluvium. feet. inches.
2. Lower chalk, Lond. and Edinb. Phil.
es 28 O
Mag. vol. vil. page 275 ... se. ose
3. Chalk-marl, 7b. page 276, 2 ft. 6 in. to 3 0
4. White zoophytic bed, 76. page 181 ... 1 4—6

A thin seam of red argillaceous matter
: ; : 0 2—S8
occurs in this place, 2b. page 181 ...
5. Red zoophyticlimestone in two beds, fee
: : - 3 10
equivalent of the gault, 7b. page 181
zane greensand. Carstone, 2d. Eee gis

8. Sandy breccia, 7b. page 176... ve 14 0

x

The dotted line points out the course of the ancient beach.

For these admeasurements I am indebted to Mr. E. Mug-
gridge of Lynn; they were taken at the highest part of the cliff.
Mr. Richard C. Taylor’s statement of the greatest depth ex-
posed of each stratum is published with his section in the
Philosophical Magazine, vol. Ixi. 1823.

* Proceedings of the Geological Society of London, vol. i. p. 60,—[also
Phil. Mag. and Annals, N.S., vol. iii. p. 299.—Ebrv. ]

Third Series. Vol. 8. No. 43, Jan. 1836. G.

42 Mr. Rose’s Sketch of the Geology of West Norfolk.

Section from Lynn to Swaffham.
a. Alluvium.
No. 1. Vegetable soil and diluvium; 2. Chalk with flints ;
3. Chalk without flints, including chalk-marl; 4. Gault ;

5. Inferior greensand; 6. Kimmeridge clay; 7. Oxford clay.
H. Hardwick Tollgate; M. Middleton; E. W. East Winch;
B. West Bilney; N. Narborough; S. Swaffham.

Map of the Valley of the Nar, &c. (vol. vii. Plate I.)

The map exhibits the localities of the shells of the brick-
earth; the course of the deposit, described page 33, will be
readily traced upon it. The marks (™) show the situation of
the quarries of carstone, and the spots where the brick-earth
is dug.

The dotted line across the map traces the course of the
gault, and serves to correct the West Norfolk portion of the
Geological Map published by the authority of the Geological
Society, as regards the course of the inferior greensand, which
is made to approach too near Swaffham : referring to the ac-
companying map, the inferior greensand occurs to the west
of the dotted line only; and to the east of it are the chalk
strata.

Note.—Since my paper was sent to the Editors, I have verified my antici-
pations (vol. vii. p. 181.) respecting the extent inland of the red chalk of
Hunstanton cliff. Having expressed my opinion to Mr. Durrant of Sand-
ringham that the red chalk extended to West Newton (the village in which
the valley of blue gault commences), that gentleman informed me he had
seen it opened in that part of his parish immediately adjoining to West
Newton. I took an early opportunity of examining the spot myself, and had
the satisfaction of seeing its outcrop, which lies in adirect line with the strike
of the blue gault; and I collected some of its characteristic Belemnites,
which were very abundant. Mr. Durrant also informed me that it occurs
at Ingoldisthorpe; and Mr. E. Muggridge has recently stated to me that it
nas been sunk through in making a well at Dersingham Mill; therefore
its course from the coast to its junction with the d/ue gault is now pretty
well traced throughout.—Sept. 11, 1835.]

[ 43 ]

X. On the Theory of Congeneric Surd Equations. By
W.G. Horner, Esq. (Ina Letter addressed to T. S. Davies,
Esq., F.RS. L. & E.)*

[If those mathematicians who have met with a quadratic equation + whose
“roots” either under a real or imaginary forin could not be exhibited,
will recall to memory the surprise with which they viewed the circum-
stance, and the attempts which they made to solve the mystery, they
will read with no ordinary gratification the following discussion of the
general question of which this formsa part. The general theory of such
equations, very happily named by Mr. Horner “ Congeneric Equations,”
is here laid dewn with great clearness, and, so far as I know, for the
first time,—as it is, indeed, nearly the first time the formation of any
general and philosophic views respecting them has been attempted.

The following letter was drawn up in answer to some passages in one
which I had a short time previvusly addressed to Mr. Horner, and was
a private and friendly communication; yet I have sincere pleasure in
having obtained his permission to publish it in the Phil. Mag. I do so
under the conviction that it will furnish the same satisfaction to others
that it has done to me. J shall only add in conclusion my hope that the
inquiry which, in the close of his letter, he has assigned to me, will
be pursued by himself, as I know no man to whom such researches can
be so safely and successfully referred.

Royal Military Academy, Nov. 15, 1835. aS: D:]

My pear Sir,

I AGREE with you in thinking that the properties of irra-

tional equations have not received that degree or kind of
attention from writers on the elements of algebra, which was
due either to the importance of the subject, or to a considera-
tion for the comfort of young students. This appears the
more extraordinary, because the methods of clearing an
equation from irrational expressions, whether involving the
unknown or not, have been so fully discussed, that really very
little remained to be done for rendering the state of the whole
case very intelligible. Waring (Med. Alg., Prob. 26.) may
be cited as a case in point. But “a miss is as good as a
mile.” In solving equations involving radicals every one has
experienced the necessity of putting his results to the proof
before he could venture to decide which of them, or whether
any of them, could be trusted; but as the latter alternative,
or the failure of every result, is of rare occurrence in books of

* Communicated by Mr. Davies.
4+ For instance, 27 + ,/x*—7 = 5, the “roots” of which are 4 and 8
as determined by the common process; neither of which substituted in
the equation reduces it to zero, These are the roots of its congeneric surd
equation 2a— f/er—7 =5, .
G2

44° Mr. W.G. Horner on Congeneric Surd Equations.

exercises, because, no doubt, the compilers had not thought
the matter out, we who use their collections, being as in-
dolent as they, have contented ourselves with the general
probability of, at least, partial success. In the mean time
even classical writers have spoken of clearing an equation
from radicals, in order to its solution, as a process of course,
and which would not in any way affect the conditions. The
consequence is, that a habit prevails of talking about equations
without any regard to this peculiar case, and therefore in
language which when applied to it becomes quite incorrect.
The term root of an equation passes for synonymous with any
quantity which, being substituted for the unknown, satisfies
the conditions; and it is affirmed, and demonstrated, that
every equation has at least one root; and that, having one, it
must have as many roots as there are units in the greatest
index attached to the unknown. It is therefore ‘quite start-
ling, when we are reminded that equations may be proposed
ad libitum, whose conditions cannot be satisfied by any quan-
tity, positive, negative, or imaginary; that notwithstanding
this, the roots obtained from such equations may be real quan-
tities. Nor is the enigma solved by discovering that the roots
obtained from one equation are sure to satisfy the conditions
of another, not much unlike it: on the contrary, one is quite
displeased at this kind of thimble-rig shuffling, where we were
assured of finding truth, the whole truth, and nothing but the
truth. A logician of the old school would settle the business
by crying ‘ distinguo” ; but we should still reply, that it is a
lame distinction which clears up only one half of the pre-
mises: we know that these are surd equations we are now
speaking of, and that just before we were speaking of rational
equations, or equations cleared of surds; but the difficulty
remains unexplained. If he really knew a little of the sub-
ject, he would, perhaps, next try the pass-word ambiguity :
** There is always a certain ambiguity adhering to surd ex-
pressions.” When, however, the most is said that can be said
to that purport, it amounts in short to this, that in the reading
of formulz, when we meet with a radical, we ought not to
use the definite but the indefinite article. We have a knack
of saying “the”, where we ought to say “a”, that is all;
and if we did but read a square root, a cube root, and so on,
we should be certain of finding one that would satisfy the ex-
isting conditions. ‘This sounds plausibly, and at least ninety-
nine out of every hundred of algebraists would inquire no
further; but you would perhaps object, that at this rate

+ ¥«ex= — ¥ x might be a good equation, unless, with

Mr. W.G. Horner on Congeneric Surd Equations. 45

Lindley Murray, we admit the “the” when the same quantity
appears a second time under the same radical; and that
without a greater latitude still, we should never be able to

prove that + YW w—ax—W x+a made —¥V x*—a’*, and so
on. So that the professed ambiguity is subject, after all, to a
conventional permanence.

The source of the whole mystery, in my judgement, is to
be found in the almost unavoidable imperfection of the man-
ner in which we are taught to transform equations when we
are at school. The operations consequent on /ransposition
are correct as far as their principles are resolvable into Eu-
clidian axioms. Beyond that they are liable to fallacy; and,
generally speaking, we are infallible in our judgement only
as long as every term is on one side. We may then deter-
mine satisfactorily i in what cases zero is admissible as the ag-
gregate value. An instance of the hazard attending the neg-
lect of this principle is given in my paper in the ‘Lond. and
Edinb. Phil. Mag. for September 1834, (vol.v.) p. 189. In the
management of surds, instances might easily be accumulated.

And whence this hazard? and why consequent upon trans-
position? Because, from the nature of analysis, we are con-
tinually arguing from the direct to the converse. An equa-
tion is formed hypothetically. We trace out certain direct con-
sequences, in the form of equations also, and so on; until an
equation is obtained, such that if the first be true, the last is
therefore true. But the converse is that which we wished to
ascertain. Is the hypothetical equation true, because the re-
sulting equation is so? ‘To determine this, a similar query
must be instituted from link to link throughout the chain of
reasoning. Is each equation in succession true, because the
next in succession is so? If each of these subordinate in-
quiries admits of a decided affirmative, the reply to the ge-
neral query is satisfactory; otherwise, it isnot. Now in the
management of equations, we have been taught, either vir-
tually or in direct terms, to rely upon certain “axioms, which
for the present purpose will be most effectually stated in
pairs, viz.

If equals be added to equals, the wholes are equals)
and,

If equals be subtracted from equals, the remainders 7 I.
are equal.

If equals be multiplied by equals, the products are)
equal; and iy

If equals be divided by equals,the quotients vi ’
equal.

46 Mr. W.G. Horner on Congeneric Surd Equations.

If equals be raised to powers denoted by equal ex-’)

ponents, the powers are equal; and

If of equal quantities roots be extracted, which SIII.

are denoted by equal exponents, the roots are |
equal.

It has never been my chance, either to hear the validity of
any of these principles called in question, or even any caution
suggested as necessary in the application of them; and yet,
when tested by the combined trial of their direct and reflex
action, they will presently appear to be very susceptible of
misuse in incautious hands.

The first and second pair, abstractedly considered, afford
such entire conviction, that in each of them, if either proposi-
tion is granted, the other can be strictly demonstrated by
means of it; and the second pair are truly corollaries to the
first. No hesitation, no ambiguity, is felt.

The fifth proposition, as a clear corollary to the third, is,
in itself, equally satisfactory ; but quite otherwise in regard
to its reflex effect, as described in the sixth. For, being aware
that if wnegual quantities (+ a, —a) be raised to power,
denoted by equal exponents, the powers may nevertheless be
equal; we are assured that, conversely, if of equal quantities
roots be extracted which are denoted by equal exponents,
the roots may nevertheless be unequal.

This remark furnishes a sufficient reason for rejecting the
third pair of principles, and consequently the ordinary me-
thod of clearing an equation from surds, For, in every in-
stance in which this is effected by transposition and involution,
in compliance with the fifth axiom, we tacitly assume that
such step can be retraced with equal certainty by means of
the sixth; whereas, in any such transit, the consequent equa-
tion may be quite true, and yet the antecedent be quite false.

If, however, we attribute the failure of the third pair of
axioms to a special ambiguity peculiar to evolution, we shall
remain under a delusion, and miss the cause and remedy of
the evil. Involution is but a single instance of the erroneous
application of the axioms of the third pair; but the use of any
of the four unexceptionable axioms is liable to be frustrated by
a similar cause, although in some cases the absurdity intro-
duced is so palpable as to occasion a kind of instinctive uncon-
scious avoidance. In other instances, however, even acute
minds have failed to observe the fallacy. This I shall now
point out, and prove that unless connected with the use of the
first pair of axioms, it will be avoided, if no member of the
equation is transposed to the zero side.

The origin of the fallacy in question will be rendered more

Mr. W. G. Horner on Congeneric Surd Equations. 47

evident by a course of amusing experiments upon a familiar
equation, é. g.

w+ 2a Te? —S8rt+12=—0,
whose roots are 1, 2, —3, —2. Applying the four axioms in
succession, we shall perceive how the incautious blending of

two truths, by means of rules in themselves unexceptionable,
will produce a falsehood.

ish To #4 22°-—7e°=—8r+12=0
Add B= «le 10

at} 2 —722°=—|F7a4+ 11 = 0;

a false equation, with regard to all the values of z, with the

single exception of 1, the value already used. Similar results

would accrue from the addition or subtraction of any other

divisor of the equation; the result will be false in every value,

except those which are also found in the equation added or
subtracted. Thus,

From 2* + 22° —72#* — 824412 @)
Take 62° — 1827 4- 12 10)
z+ 22 — 132° 4+ 102 = 0;
whose only correct roots are those also of 27— 347+ 2 = 0.

2ndly, The given equation is resolvable into the quadratics
2—3r+2=0, anda’ +57+6=0.

Therefore, multiply 2 — 3r=— 2
by e+ 5br=— 6
GE Da ae AG a= ~ 18%

a statement altogether erroneous, not containing a single cor-

rect value of z.
On the other hand, divide

a4+20% —~72? —8e = —12
by a’? —32e= — 23
P+ 2a —7T«4#—8
Hes = 6,
xr—3
* P+I92r*—138 2 =— 10:

incorrect, except in respect of the roots of z°— 37+2 = 0.
You will clearly perceive, without dwelling upon the distine-
tion of cases, the very simple nature and origin of the para-
dox. The axioms speak of quantities which are s?multaneously
equal; but no two roots of an equation, unless they be equal
roots, are coexistent: if e = 1 it is not at the same time = 2.
Consequently, as in each of the examples v in the upper of
the two equations has some yalues, which substituted in the

48 Mr. W.G. Horner on Congeneric Surd Equations.

lower will render its sides unequal, the results, as far as such
values of 2 are concerned, are no longer coincident with
the conditions of the axioms on which the management of
equations is founded, but are illustrations of the opposite
axioms, viz. that unequals added to, or subtracted from, or
multiplied or divided by, equals, produce wnequal results, or
in algebraic language, false equations.

The reason why this inconvenience, in the use of the se-
cond pair of axioms, cannot occur when all the terms are on
one side and zero alone on the other, is very evident; al-
though, by another of those paradoxes by which equations
are beset, the complete truth appears at first sight to be the
result of combining a truth with an error, and equals to re-
sult from combining equals with uneguals. It is, however,
easy to avoid all suspicion of error. ‘Thus, it was said, that
the given equation is resolvable into a* + 3a + 2 = 0,and
w2+5x+6=0. But as these statements are not s/multa-
neously true, but, on the contrary, any value of 2 which satis-
fies one of the quadratics will render the other = A, some
numerical quantity differing from 0, we in fact collect the

product of e — 32+ 2 = 0, or A;
by ge ar + 12’*= Ay or ©,

in finding (2? — 3x2 + 2) (a + 72 + 12) = 0; where the
premises being strictly correct, the result is unexceptionable.
And the same result arises, although not with equally clear
evidence of its truth, when A is superseded by zero.

The same test, of a hypothetical adjustment of one of the
two proposed equations, would at once expose the fallacy of
each of the conclusions attained in our imaginary experi-
ment.

The general propriety of keeping the zero-side of each
equation in a. chain of argument clear from any transposed
terms, is proved therefore by the liberty which it allows to
the mind, of conceiving any zero, which happens to be pro
tempore incorrect, to be superseded by the correct value, and
of perceiving without any embarrassment or additional Jabour
the exact conditions of the final result. But the especial pro-
priety of adhering to this expedient, when surds are to be ex-
tricated, appears in the necessity which it imposes of attending
to the copula of the argument, the suppression of which in
the vulgar process occasions all the obscurity that is com-
plained of. ‘Thus, between the statements

II

a@a=Vf/nr or a4—-wVe (0)
and Cm.” or a —) we ud

Mr. W. G. Horner on Congeneric Surd Equations. 49

the copula a+ /r=A has been lost sight of. ‘The com-
plete chain is
We I FS OOr Fe
a+ /x=A, or 0
Sc Ga Ch OQ.

You are well aware that this copula will, in all cases of surd
equations, consist of all the variations that can be made of
the given formula by varying the affection of each radical it
contains in all possible ways. You also can refer, more readily
than myself, to various authors in whose works the method
of forming the continued product of a formula and all such
variations of it (for the sake of a convenient term I would ven-
ture to say, its congeners) has been simplified. You see, that
by retaining the entire set of congeneric equations, all doubt
respecting the constancy of every symbol employed, whether
letter or radical sign, is entirely cleared away. Uncertainty,
indeed, still remains attached to the results of the solution of
the final equation; namely, uncertainty as to which of the
congeneric formule will be reduced to zero, by the resulting
values of x; but this doubt is unconnected with any perplexity
respecting the general theory.

A very unnecessary ambiguity is admitted in the current
acceptation of the word root; and great advantage would ac-
crue from restricting it to its only legitimate signification of
“such a value of the unknown in any linear divisor of the
equation, as will cause that divisor to vanish.”

The sum of the whole matter, respecting surd equations,
I conceive to be this. We know that the continued product
of a surd formula and all its congeners will produce a ra-
tional formula; and that such rational formula, being equated
to zero, may be solved by as many roots as it has dimensions.
We are also certain that each of these roots will cause one of
the congeneric surd formule to vanish ; otherwise the product
of all would not be = 0 as assumed. But, is the value of x
which effects this, to be called a root of the surd formula?
No, it is a root of the rational combination only.— Have irra-
tional equations, then, no roots? None at all.— What have
they, then, in the place of roots ? An equitable chance, in com-
mon with each formula in the congeneric society, of solution
by means of the solution of the stock-equation.—But if an
equation has no root, nor even a certainty of solution, in what
form can it be intelligibly proposed? A note of interrogation
subjoined might serve to intimate that the equation is pro-
posed either for solution or correction—To what order can

. ‘ F m ,
surd equations be assigned ? To the fractional order >? when
’

Third Series. Vol. 8. No. 43. Jan, 1836. H

50 Letter from the Rev. Dr. Lardner to Peter Barlow, Esq.

n congeneric formule produce a rational equation of the mth
order ; thus, ;

22+ 7% 2° —a = Bb? is of the 2 order.
at J wt Jf BHO? =jOl° de secces
6

aWYate—-Va—x= 0? §......
Are the chances of solution equal for each individual congener?
I leave that question in good hands, and remain,
Yours, very affectionately,
Bath, Nov. 12, 1835. W. G. Horner.

XI. Letter to Peter Barlow, Esq., F.B.S., Sc., Sc., respecting
some parts of his Reports addressed to the Directors and Pro-
prietors of the London and Birmingham Railway Company.
By the Rev. Dionysius Larpner, LL.D., F.R.S., &e.

Dear Sir,

ig was not until my return to London within the last few

days that I had the pleasure of receiving a copy of your
Second Report addressed to the Directors of the London and
Birmingham Railway Company. The previous communica-
tions which had passed led me to anticipate some collision
of opinion between us, but I confess I did not expect that
any difference should exist on a question of a nature so ele-
mentary as that which you have noticed in your Report. In
page 87 you say:

‘“‘ If (as was assumed in the Parliamentary Committee on
the question of the Great Western Railway) as much power
was gained in the descent as was lost in the ascent, the odds
would be made all even. But that assumption is altogether
erroneous both in theory and practice.”

And again, in page 91, you say, referring to your theory of

the deflexion of bars:

“The only doubt, therefore, which can remain is, how far
I ought to reject as inconsiderable any increase of power on
the descending side. This point cannot be met experimen-
tally, and I am therefore obliged to depend here only on de-
monstration. The case certainly involves no difficulty of con-
ception to those acquainted with theoretical mechanics; but
the question having been seen in a different light by a gentle-
man of considerable scientific eminence, I should have been
glad to have exhibited the effect experimentally; but as the
whole turns upon velocity, this is of course impossible.”

To those who have taken an interest in the question respect-

on the Theory of Gradients in Railways. 9

ing the effect of gradients, raised in my evidence before the
Great Western Railway Committee, and subsequently more
fully developed by me at the meeting of the British Association
in Dublin, it will of course be evident that I am the person
here alluded to. But since your Report must needs fall into
the hands of many persons who have neither seen my evidence
before Parliament, nor heard the discussion in Dublin, I think
it right to explain briefly what the conclusions are at which I
arrived, and which you declare to be erroneous both in theory
and practice.

There are on railways certain inclined planes, forming so
small an angle with the horizon, that a load placed upon them
will not descend by its gravity, the friction being greater than
the tendency down the plane by gravity. Let the angle of
elevation of such a plane be «, and let the greatest angle of
elevation which is compatible with this conclusion be ¢. I
shall call this angle, «’, the angle of repose. Now let us sup-
pose an inclined plane at the inclination «, the length of which
expressed in feet is L: let a load be placed upon the plane,
the amount of which we shall take as the unit of weight. Let
t be the ratio of the friction to the pressure peculiar to the
nature of the road, the carriages, &c. which is of course a con-
stant quantity, so long as the carriages and the road continue the
same. Now the pressure upon the plane will be expressed by
cos‘; but as « must be a very small angle, we may, without
sensible error, take cos ¢ = 1, and consider the whole weight
as pressing upon the inclined plane. In fact, ¢ is an angle
so smal] that its sine does not exceed 0°004, and « being still
stnaller, it is clear that cos¢ is so nearly equal to the unit that
we are justified in this assumption.

To determine the tractive force which must be applied to
the load to draw it up the inclined plane, it is only necessary
to add together the forces necessary to overcome the friction
and the gravity: now the friction is ¢, and the gravity sin ¢;
therefore the force which resists the motion up the plane will
be¢+ sine. The moving power, therefore, which will keep
the load moving up the plane at a uniform speed will exert a
pull upon it which shall be expressed by ¢# + sine. The unit
being the weight of the load, it is clear that the total expendi-
ture of mechanical power in drawing the load the entire length
of the plane will be expressed by L (¢ + sin «).

Now to estimate the mechanical force necessary to draw the
load at a uniform speed down the plane, we have only to con-
sider that the force which is opposed to the drawing power is
the friction ¢, diminished by that component of the weight of
the load which is directed down the plane, and which of course

H 2

52 Letter from the Rev. Dr. Lardner ¢o Peter Barlow, Esq.

conspires with the drawing power. ‘The effective resistance,
therefore, to the drawing power will be ¢sin s, referred to the
weight of the load as the unit. The total expenditure of me-
chanical force, therefore, necessary to cause the required de-
scent will be L (¢ — sine). Now if we wish to determine the
whole rnechanical power expended in ascending and descend-
ing the plane, it is only necessary to add L (¢ + sin «) to L (¢—
sine): the sum is2 L¢. Now it is obvious that this would be
the amount of mechanical force expended in drawing the same
load backwards and forwards on the level plane of the length L.

If the angle of inclination of the plane were the angle of re-
pose, then the tendency of the weight down the plane by its
gravity would be precisely equal to the friction or sine’ =¢:
there would in fact be no resistance to the motion down the
plane, and consequently any velocity imparted to the load
down the plane would be continued uniform without any
drawing power to the bottom, supposing of course the plane
to be free from the inequalities which would alter the amount
of friction.

To ascend such a plane, on the other hand, would require a
drawing force of twice the amount necessary for a level, since
t+ sine =2¢; and we accordingly arrive at the same con-
¢lusion,—that in ascending and descending planes whose in-
clinations do not exceed <’, the total expenditure of mechanical
power is the same as on the level, the only difference being
that on the level it is expended by one continued uniform
éxertion, and that on the inclinations it is greater in the as-
cent and jess in the descent, the mean being the amount upon
the level.

T explained fully, both before Parliament and at the British
Association, that this reasoning would not extend to greater
elevations thax ¢', for that in these cases the power saved in
the descent wonld be less than the excess expended in the
ascent, and that, consequently, such gradients would always
occasion a loss of mechanical power.

Now really this conclusion is so plain a result of first prin-
ciples that I have been utterly at a loss to discover in what can
originate our difference of opinion about it. It struck me,
therefore, that this discrepancy must have its origin, not in
the above reasouing, but in some difference of conception re-
specting the very foundations of mechanical science. It oc~
curred to me, therefore, to look over your Reports, to. see
whether the same difference as to first principles would lead you
to conclusions upon other points different from those at which I
should have arrived: in this I was not disappointed, for I found
in another case, in which the force of gravity is considered, and

on the Theory of Gradients in Railways. 53

indeed one which is the extreme case of an inclined plane, viz.
that of a perpendicular fall, you have arrived at a conclusion
which certainly is totally at variance with the views which I
have been accustomed to take of the theory of forces. In
your First Report to the Directors of the London and Bir-
mingham Railway Company, page 90, in speaking of the effect
produced by the wheels of wagons passing over the joints of
rails where one has sunk below the level of the other, so as to
form a sort of slip, you say:
_ «It has perhaps never occurred to such persons that a dif-
ference of level at a joint-chair will, when the carriage is moving
from the higher to the lower level at its greatest speed, cause
the wheel to pass the distance of a foot without pressing on the
rail, and consequently throwing the whole weight, which ought
to be borne equally by the two rails, wholly upon one. Yet
this is a fact resting upon a natural Jaw, and cannot be other-
wise. To fall th of an inch by the action of gravity requires
gzth part of a second, and in that time the carriage will have
advanced a foot, and consequently in that space the whole
weight has been borne by one rail only.”
_ I freely confess that I am one of the persons you allude to,
to whom such an idea never would have occurred. I am en-
tirely ignorant of the natural law to which you allude, but I
am not ignorant of a natural Jaw which is altogether incom-
patible with your conclusion; and my conviction that the
whole weight cannot press on the remaining wheel is quite as
clear and strong as yours is that it will so press. It is quite
true that the force of gravity will cause a body to fall freely
jisth of an inch in J,th part of a second, but when the force
of gravity is thus employed it cannot at the same time cause
the whole weight of the same body to press upon a fixed point.
The fact is, that when the wheel passes from the higher to the
lower level, the centre of gravity being unsupported falls, and
the only pressure exerted upon the remaining wheel depends
on the moment of inertia of the load in receiving an incipient
angular motion, and it is evident that this pressure must be
extremely slight; but, whatever be its amount, it is totally dif-
ferent both as to effect and cause from that which you allude
to. If you consider that during the moment of a perpendicular
fall, in the case of one rail being below the level of the other,
the weight while it falls still presses with its whole force upon
the rails, your view even of the most elementary principles of
this part of mechanics is so essentially different from mine,
that the wonder is, not that we should differ in one instance,
but that we should agree in any.

Referring again to your second Report, where you have

54 Letter from the Rev. Dr. Lardner to Peter Barlow, Esq.

noticed my inferences respecting gradients, I find that you say
that, ?

“‘ As the question wholly turns upon velocity, it is of course
impossible to exhibit the effect experimentally.”

Now although I do not perceive this to be at all a matter
of course, but on the contrary have found it very easy to
reduce questions depending on velocity to experiment, yet I
beg to observe that the present question does not depend
either wholly or at all upon velocity. Whatever be the speed
of the load upon the inclined plane, provided only it be main-
tained uniform, my theory of gradients (if it deserve to be so
called) will still hold good. It will take the same expenditure
of mechanical force to move a load on such inclined planes as
I have described, and the mean between the ascending and
descending forces will be the force along a level plane. You
must surely be so well acquainted with the laws of friction that
it is needless for me to remind you that that resistance is alto-
gether independent of the velocity. And I would also beg to
observe that the case is one totally distinct from the consi-
deration of accelerating forces. In page 91 you say:

“This point cannot be met experimentally, and J am there-
fore obliged here to depend only on demonstration. The case
certainly involves no difficulty of conception to those acquainted
with theoretical mechanics, &c.”

I admit that it does not; but I apprehend the conception
which those acquainted with theoretical mechanics form of it
will be altogether different from that at which you appear to
have arrived, and I therefore regret that you seem to have
forgotten your expressed intention of giving a demonstration
of your own peculiar view of the matter. In the next page
(92) you mention the intention as one which you dad, but seem
to have immediately abandoned it.

It will be very gratifying to me, and I am sure it will be
useful to all who are practically engaged in those extensive
enterprises for the formation of lines of communication through
the country, if you will show how these views of mine are at
variance with the established principles of mechanics. Al-
though I am not aware that any one has hitherto pointed out
the property which I have explained in reference to inclined
planes of less inclination than the angle of repose, yet, so far
as I am informed, there is no difference of opinion whatever
as to the legitimacy of the method of estimating the tractive
force both in ascending and descending these planes. The
same formulz that I have used, viz. L (¢ + sins), have been
in substance universally adopted in estimating the mechanical
force necessary to work railroads. You will find that many

Dr. Ritchie on a supposed new Law of Magnetic Action. 55

eminent engineers, althongh they have not thrown the prin-
ciple into the language of analysis, have nevertheless used it
arithmetically ; and indeed I have never before heard any
doubt expressed about it.

During the Jast autumn I have been engaged in an exten-
sive course of experiments on rail-roads in different parts of
the kingdom, with a view to determine with greater precision
than has been hitherto attained, the values of the different con-
stant quantities which enter into their theory. The results of
all these experiments are in the most perfect accordance with
the principle you have called in question.

I remain, dear Sir, yours very truly,
Dron. Larpner.
36, Cambridge Terrace, Edgeware Road,
December 14, 1835.

XII. Remarks ona supposed new Law of Magnetic Action. By
the Rev. Witiiam Ritcuie, LL.D., F.R.S, Professor of
Natural Philosophy in the Royal Institution of Great Britain
and in the University of London.*

N the last Number of the London and Edinburgh Philoso«
phica! Magazine}, Mr. Fox has endeavoured to show
that the mutual attraction of two magnets does not follow
the law formerly adopted by all philosophers, viz. the law
of the inverse square of the distance ; but the law of the simple
inverse of the distance. This law he deduces from experi-
ments on the attraction of the opposite ends or poles of mag-
nets placed at very small distances from each other. Thus,
for example, when the ends of the magnets are at the distance
of 5555 of an inch, he found the effect to be only one half of
what it was when they were in contact; when removed to the
distance of =,55 of an inch the effect was one half of one half,
or one fourth; when separated by a distance of ;1, of an inch,
the force was only one half of one fourth, or one eighth, &c.;
which numbers are to each other in the inverse ratio of the
distances
I admit the truth of the experiments, but differ from Mr.
Fox in the conclusion he has drawn from them. To show
that the deduction is unfounded, we must first describe what
is meant by the pole of a magnet, and its position with regard
to the extremity of the magnet. The pole of a magnet is
the centre of parallel forces of all the attractions and repulsions
of the elementary magnets of which it is composed. Now the
position of this centre will obviously depend on the form of

* Communicated by the Author, t Vol. vii. p. 439,

56 Dr. Marshall Hall’s Description of a Thermometer

the magnet, and also on its ength. Biot has shown that ina
steel wire 24 inches long, and properly magnetizef, the pole
is an inch and a half trom its extremity, and that this distance
diminishes with every diminution in the length of the mag-
net *. The centre of parallel forces or the pole of a magnet
is similar to the centre of gravity of a body. In the one case
the effect is the same as if all the matter of which the body
is composed were concentrated in the centre of gravity, in the
other the effect is the same as if the difference between the
sum of all the attractive and repulsive forces were concen-
trated in the pole. Now, in the case of the mutual attrac-
tion of bodies, our measurements are always taken between
the centres of gravity; in the case of magnetic attractions the
distances of the magnets are, in fact, the distances between

the poles.

Let the distance of the
poles of the magnets when 1 rr
in apparent contact be call- a Ate ba

ed2, as in fig. ( L.),and then (2.) * c ~
separated bY, an ae Lot ——
of 1, as in fig. (2.), anc gi) 35 a ——
by intervals of A as in (3+) nnssltetl

fig. (3.)

Then the distances between the centres of force in these
three positions are 2, 3, 4. Hence if the law of the znverse
squares of the distances, investigated by Coulomb, be the
real law of action, the attractive forces will be inversely as
2°, 3°, 4°, that is, as 4, 3, 7,3; but 4 is nearly the half of one
fourth, and ;4, nearly the half of 4, as Mr. Fox found by
actual experiment. ‘These experiments then, instead of lead-
ing to a new law of action, afford a beautiful illustration of
that law which universally prevails whenever we have matter
acting on matter by attractive or repulsive forces.

XIII. Description of a Thermometer for determining minute
Differences of Temperature. By Marsuary Hatt, M.D.,
ERS. Se. ¢

| pursuit of the theory of the inverse ratio of the respira-

tion and of the irritability in the animal kingdom, an-
nounced in a late volume of the Philosophical ‘Transactions,
I have found it absolutely necessary to determine the minute

* Biot, Traité de Physique, tom. ili. p. 90,

+ Communicated by tke Author.

+ An abstract of Dr. Marshall Hall’s paper on this subject will be found in
Phil. Mag. and Annals, N.S, vol. xi, p. 453.—Epir. :

for determining minute Differences of Temperature. 57

differences of temperature which exist in animals
of the same class. In pursuing this inquiry, I soon
discovered that it was essential to devise other
instruments than those in ordinary use.

It was easy by enlarging the bulb and by select-
ing a tube of extremely fine calibre, to render the
common thermometer capable of more minute in-
dications. But it was impossible to carry this
change beyond a certain degree, the augmented
length of the instrument becoming highly incon-
venient.

In order to obviate this difficulty, I devised the
instrument which I am now about to describe.

The form of this instrument is represented in
the accompanying outline. The relative size of the
bulb and calibre of the tube is such that the tenth
part of a degree occupies a considerable space
upon the scale. ‘The entire scale consists of ten
degrees. At the upper part of the thermometric
tube a small bulb is blown, which I shall desig-
nate the reservoir; it is turned forwards so as to
remain at a right angle with the tube. Al

The bulb and the tube are filled with mercury,
and a little of that fluid is included in the reser- 9,
voir, when the whole is hermetically sealed.

When an experiment is to be made, the mer-
cury in the tube is to be brought into contact with
the mercury in the reservoir, by placing the in-
strument horizontally, with the reservoir upwards, in water of
a sufficient temperature.

I will now suppose that I wish to try the comparative
temperature of the swallow which shuns, and the sparrow
which abides, the rigours of our winter. The thermometer
is removed from the water at the temperature of 110° Fahr.,
and placed upright. The contiguity of the mercury in the
tube with the mercury in the reservoir being broken, the
highest point in the scale will represent that degree, viz.
110°. The lowest will consequently be the 100th degree.
The entire scale is one of six degrees between these extremes,
each degree being divided into tenths.

The same plan is adopted for any other part of the scale.

We have thus an instrument of the usual size, capable of
measuring the tenths of a degree of temperature, at any
part of the scale. It only requires the addition of a common
thermometer to afford the extreme limit of the magnified
scale.

Third Series. Vo\. 8. No. 48. Jan. 1836. I

58 British Association for the Advancement of Science.

I may be permitted to add, that the temperature of an ani-
mal indicated by such a thermometer compared with that of
the medium in which it is placed, affords a near approxima-
tion to the degree of respiration, and, inversely, of the irrita-
bility of the muscular fibre.

LXV. Proceedings of Learned Societies.

OFFICIAL REPORT OF THE PROCEEDINGS OF THE BRITISH AS-
SOCIATION FOR THE ADVANCEMENT OF SCIENCE, AT THE
DUBLIN MEETING, AUGUST 1835.

Communicated by the Council and Secretaries.
(Continued from vol. vii. p. 513.)

Notices and Abstracts of Miscellaneous Communications to the Sections,
continued.

MEDICAL SCIENCE,—continued.

Experimental Inquiry into the different Offices of Lacteals, Lym-
phaties, and Veins in the Function of Absorption. By P. D.
Hanpysipe, M.D.

Fe author’s general position is thus stated: “ The lacteals, lym-
phatics, and veins are endowed each with a peculiar office in the

general functions of absorption ; for example, 1. The lacteals are
those vessels which absorb the aliment which is necessary for main-
taining the nutrition and increase of the body, and exercise the
property of refusing entrance to all other matters; 2. The lympha-
tics absorb the elements of the body upon their becoming useless or
noxious, so as by their final discharge from the system to make room
for the deposition of new matter, and these vessels possess no ab-
sorbing power over any substances foreign to the system; 3. The
veins not only return to the heart the blood after that fuid has ful-
filled the object of its diffusion over the system, but enjoy the office
of receiving into the animal system by absorption various foreign
matters which may be brought into contact with their orifices.

In support of these views the author presents a short review of
results obtained by various eminent anatomists and physiologists.

The following is the order of the subjects discussed :

Lacteals.—Their distention after a full meal,—their condition as
observed in living animals ;—effects of ligatures on the thoracic
ducts of horses.

Lymphatics,—Anatomical origin of,—analogy of lymphatics and lae-
teals,—exact resemblance of the lymph prior to its absorption to
that found in the lymphatic vessels,—absence of lymphatics in
vegetables,—no proof afforded by examination of lymph that
lymphatics serve as the channel through which foreign matters
gain entrance into the system,—no communication between lym-
phatics and veins except through the great lymphatic trunks.

Veins.—Analogy between the anatomy and disposition of the veins
of animals and the vessels corresponding to these in plants, favours,
the doctrine of venous absorption.

Section of Medical Science. 59

“ When foreign matters capable of affecting the constitution ge-
nerally, and of being diluted in its solids and fluids, are brought
into contact with the serows and mucous surfaces of the body,
with the ewtis vera, and with the interstitial cellular tissue of dif-
ferent organs, the resulting phenomena exhibited by the blood
in the veins give evidence that these vessels are the sole agents
employed in this variety of absorption.” These four points are
discussed by reference to a variety of experiments, to which the
author adds the following from his own researches, as bearing on
the question of absorption of foreign matters by veins of the cel-
lular tissue.

Exp. 1. Having made a fistulous opening in the abdominal parietes
of a dog, he took advantage of the period when a complete granu-
lating surface should be formed, to apply to it very freely the solu-
tion of pruss. potass. On killing the animal three minutes after the
application, and applying the appropriate chemical test to the blood,
it was seen to exhibit traces of the prussiate.

Exp. 2. He induced the formation of a granulating surface four
inches square in extent in the fleshy substance of the back of a
large cat, and then retained pledgets of lint moistened with 13 of the
usual solution of the prussiate of potash in contact with this surface
daring the space of four hours. A fair indication of the presence
of the poison in the blood was seen, on submitting to the usual test
the blood from the carotid arteries, both in its fluid and coagulated
states, while no indication whatever of its presence was observed in
the lymph.

These experiments now put forth as evidence in favour of the
doctrine of absorption by the veins of foretgn matters, from the 7-
terstitial cellular tissue of the animal body, when taken along with
the previous experiments also adduced to prove the absorption of
foreign matters from the surface of the eutis vera and the different
mucous and serous superficies, would appear to justify a conclusion—
that the absorption of foreign matters occurring from the interstices
and surfaces of the body occurs solely through the channel of the
venous system.

Observations on the effects of Cold on different parts of the Human
Body, and on a mode of measuring Refrigeration. By Dr.
OsBORNE.

In this communication Dr. Osborne began by adducing some
facts to show the importance of cold, viewed as a cause of disease.
He stated, that of 57, the entire number of patients on the preced-
ing day (13th August, 1835,) in Sir Patrick Dun’s Clinical Ho-
spital, 34 could distinctly refer to cold as the cause of their com-
plaints, contracted in the following manner: in 12 from damp
clothes, 5 from damp feet, 3 from bathing, and 14 from cold air
when heated. This proportion, however, would probably be very
different in winter. The direct effect of cold on the air-passages of
the lungs is almost restricted to inflammation at the rima of the
glottis, and this is usually caused by suddenly rushing from heated

60 British Association for the Advancement of Science.

to cold air. It may be proved that the respired air, being of nearly
the same tempevature as the blood, and not deriving its heat from
the action of respiration in the lung (see Brodie’s Experiments),
must, in its passage downwards, be heated to considerably more
than half the difference between the temperature of the blood and
that of the air; that, consequently, at its arrival in the air-vesicles
of the lungs, it must have acquired such a temperature as amounts
to a protection against the effects of cold. Dr. Osborne considers
this as a provision of nature in a matter in which we are not able
to guard ourselves.

When, owing to an oppression of nervous energy, the healthy
temperature of the surface is not maintained, then the air arrives at
the air-vesicles without being heated; hence, he conceives, may be
explained the numerous instances of sudden death which oceur in
chronic bronchitis and low fevers when sudden depressions of the
temperature of the atmosphere have taken place during the night.
In those cases the cold thus admitted to the lungs causes a torpor in
their capillary circulation ; and after death it is found that the blood
has stagnated in the lungs, and in the veins and right cavities of the
heart.

The common opinion that various inflammatory diseases are con-
tracted by sleeping in newly-built houses appears to be ill founded,
except in as far as the clothes worn by the individual may contract
moisture. The air under the bedelcthes being kept up by the heat
of the body to the temperature 80°, the only way in which the damp
air can prove injurious is by the lungs, which, as before stated, are,
in health, enabled to resist its effects. It appears that in a regiment
which was quartered in newly-built barracks no injury resulted from
the damp.

On the stomach the effect of cold is perceived, not by a sensation
of cold in that organ, but by thirst, in consequence of reaction, a&
is experienced after taking ices. When the cold is long-continued
or overpowering, in consequence of feeble reaction, then gastritis is
produced from torpor of the capillaries. This last mode of expla-
nation is derived from the phenomena observed in the exterior of the
body on the application of cold. When the application is transient and
the circulation vigorous, the contraction of the vessels and paleness
of the surface are only momentary, and are succeeded by reaction
evinced in increased heat and diffused blush of redness. When it is
long continued, then the pale and shrunk state of the surface is gra-
dually succeeded by a purple or livid colour, attended with increase
of size, as may be proved by a ring on the finger, from the swollen
state of the vessels. Comparing these facts with the experiments de-
tailed by Dr. Alison,—which showed that in inflamed parts not only
the small vessels but the large arterial trunks leading to the part are
dilated, and veadered incapable of contracting like other arteries,—
Dr. Osborne proposes the question, whether there is not sufficient
evidence to prove that cold produces inflammation by producing
torpor and dilatation of the vessels, either of the part itself or of
some connected or adjacent part, which, if not removed by transient

Section of Medical Science. 61

reaction, is followed by the more permanent reaction of inflamma-
tion, causing a number of new phenomena.

With regard to the effect of cold on the skin, which is the most
important of all, it is evident that meteorology has contributed very
little to our knowledge of the influences of the atmosphere on health
or disease. It has appeared to the Author, that in order to connect this
science with utility, as far as mankind is concerned, one considera-
tion has been omitted, which is, the cooling power of the atmosphere
estimated with reference to ourselves. The human body has a heat
of nearly 98°, and is placed in a medium always cooler than itself.
The degree of cooling influence exerted on it has never been made
the subject of measurement, and to the present time is estimated
solely by the feelings. In order to measure the cooling influences
of the air or other media, Dr. Osborne used a spirit thermometer,
without a frame, carefully graduated from the degree 90 to 80 in-
clusive, that being nearly the temperature of the exterior of the body.
Having heated the bulb to 90°, he exposed it in different situations,
observing the time during which the spirit descended from 90° to 80°;
and adopting, as a measure of the refrigerating power, the rate of
cooling deduced. And by this contrivance is exhibited the result
of radiation, and of the conducting power of the atmosphere as
modified by its temperature, its density, its moisture, and its cur-
rents; and that result, the most interesting of all to the invalid,
who, in respect to temperature, may be conceived as represented
by the instrument. As the variety in the shape of the bulb, the
bore of the tube, the thickness of the glass, or the density and
quantity of the fluid employed will cause variety in the time of the
descent, the result obtained with two thermometers must not be ex-
pected exactly to correspond. In order to procure uniformity for
this purpose, it will be necessary to place a number of them, pre-
viously graduated between 90° and 80° and heated to 90°, in air at
60° or 50°, and to select those which contract according to the time
fixed on as a standard. The thermometer so applied, Dr. Osborne
proposes to call a psychometer, or measurer of refrigeration.

Amongst the observations brought forward by him to illustrate
its use are the following:

To show the refrigerating effect of agitation or of a breeze, the
temperature of the air remaining the same.

In air, temp. 70° at rest, it cooled from 90° to 80° in 5™ 208.
in a slight, breezes... sas. danssbeosr cn UUZ™ 508,
blown on with a bellows ............in 58%.

These observations show the fallacy of determining climate by
the thermometer. ‘There are situations in which, owing to constant
currents of air, a cold is produced of the utmost consequence to
health, but not appreciable by the thermometer. Dr. Osborne ex-
pects that by means of this mode of observation much light may be
thrown on the climates of the western coast of Africa, and of other
unhealthy localities. The meteorological tables at present kept in
those places fail in showing the effect of the sea and land breezes.

The following shows the refrigerating power of water above air
of the same temperature, at rest, to be above 14 to 1.

62 British Association for the Advancement of Science.

In air at rest, temperature 70°, it cooled from 90° to 80° in 5™ 405.
In water at rest, same temperature.........secceceeeeeeeeeees IM 248,

It is well known that in swimming it is not the fatigue so much
as the refrigeration which fixes the limit. This appears from the
following observation compared with the preceding.

The instrument agitated in water, cooled from 90° to 80° in 15°.

In order to ascertain the refrigeration produced by damp clothes,
Dr. Osborne covered the bulb of the instrument with cotton wool,
and having placed it at rest in an apartment at 683°, found it to cool
from 90° to 80° in 10" 148. Placing it in the same circumstances,
but with the cotton wool slightly damped, it cooled down in 2™ 57%.
This proportion must be much increased when under the influence
of the open air. The application of cotton wool to the skin, moist-
ened with water or an evaporating lotion, he has found the most
eligible means of cooling the surface in disease, not only on account
of the constancy with which the refrigeration is maintained, but
from its being peculiarly agreeable to the feelings of the patient.

On the Influence of the Artificial Rarefaction or Diminution of At-
mospheric Pressure in some Diseases, and the Effects of its Con-
densation or increased Elasticity in others. By Sir JAMES
Murray.

The paper was divided into two parts. The first detailed the ge-
neral principles of the rarefaction of air, and its powers as a reme-
dial agent on the human body. The second part related to the local
agency of condensation of air in topical diseases.

The propositions were submitted, not as remedial means of them-
selves alone, but as auxiliary to those already in use. It was shown,
That the ordinary atmospheric pressure sustained by the whole body
averages 15 tons ;—that by placing a person in an air-tight bath, with
provision for breathing the ordinary atmosphere, half a ton or a ton
can be removed without danger :

That the abstraction of this elastic compression permits the easier
expansion of the chest, elicits the bleod and animal heat to the sur-
face of the body, opens the pores of the skin, and restores to the
surface rashes or eruptions which had been suppressed.

It was therefore submitted, that an agent capable of producing
such effects is entitled to consideration in treating certain conditions
of pectoral diseases; in eliciting internal congestions or inflamma-
tions from central organs to the surface ; in preventing certain fevers,
and other complaints arising from obstructions of the cutaneous
functions; in translating gout and rheumatism from vital organs to
the limbs ; in restoring a due balance of the circulation, and attract-
ing the blood into the superficial veins from the deep-seated arteries.

A case of a patient was detailed, in which congestion of the brain
was diverted from the head by inclosing one of the lower extremi-
ties in a rarefying bath, and abstracting about two pounds and a half
of pressure from each inch of the surface: the influx of the fluids
was so great, that in two hours the circumference of the limb was

Section of Medical Science. 63

increased nearly three inches, the vessels of the skin rendered red,
warm, and turgid, and the head relieved.

The case of a painter was also adduced, whose right arm had long
been paralysed and cold from the effects of lead paint. The arm
was put for two hours into the rarefying case, and afterwards con-
tinued hot and vigorous, so that the man was able to resume his
work.

Part second.—As diseases of an opposite nature require opposite
remedies, the principle of rarefaction is reversed in certain cases,
and condensation, or additional pressure, employed.

This part of the paper detailed several cases illustrative of the powers
of this agent. Where there was too much vascularity of parts, then
local pressure, pumped under an air-tight covering, emptied the vessels,
propelling onwards the overflow of blood contained in the veins, and
preventing its undue influx by the arteries.

The consequences were, to diminish inflammations, dissipate tu-
mours and white swellings, facilitate the reduction of hernia and other
protrusions, and to diminish the influx of fluids into indurated
breasts or enlarged glands.

The author adduced a very interesting case, the reduction of a
prolapsus ani by atmospheric pressure, without touching or bruising
the sensitive intestine.

The powers of condensation of air were then alluded to, for the
treatment of fungous sores or ulcers, and for the suppression of
uterine hemorrhages, as well as bleeding from wounds or lacera-
tions *.

On the Differential Pulse. By Dr. WDowne tt.

Dr. M’Donnell’s paper began with a description of what he terms
“the Differential Pulse,” and with proofs of his claim to priority in
ascertaining it in 1784. The observations which succeed related to
the following subjects.

The influence of disease and of particular remedies upon the
pulse, with a reference to the effect of posture on the number of
beats; the absence of this phenomenon in quadrupeds, owing to
their natural vessels being horizontal in both the lying and standing
posture ; certain cases of health and disease, in which the maximum
and minimum of this variation are found ; the methods to be pursued
for investigating the number of the pulse in wild and ferocious ani-
mals as deducible from their respirations ; the proportion between the
stops, pulses, and respirations in man and quadrupeds in active ex-
ercise ; observations made at a depth of 26 feet in a diving-bell,
which corroborate the views of Sir David Barry and Dr. Carson on
the moving powers in the circulation; proofs that barometrical va-
riations have no influence upon the pulse or breathings.

Part 2.—On the limitations of the doctrine of the “ Differential

* In vol. xiv. of the Philosophical Magazine, First Series, p. 293, was
published a paper on Smith’s Air-Pump Vapour-Bath, an instrument which
. was designed to effect, by the same means, many of the objects contemplated
by Sir J. Murray.—Epir.

64 British Association for the Advancement of Science.

Pulse”; of stationary or permanent pulses; observations made on
the pulses of children before and after their having respired ; of the
acceleration of the pulse after birth; observations on quadrupeds
with respect to this; supposition that the foetus remains before
birth in the state of the cold-blooded aninials; of the final cause of
this peculiarity; of the cause of the stethoscopic sounds of the
foetal heart being very rapid, although the pulse in the funis be slow ;
an account of an experiment made by a watch ticking under water ;
of the remarkable strength of the fcetal pulse as felt in the chord;
of the absorption of the blood in the chord into the system of the
foetus after delivery ; and the inference from this in favour of the
views of Sir David Barry and Dr. Carson respecting the suction power
of the thorax as influencing the circulation.

On some hitherto unobserved Differences in the Effects of Accumu-
lations of Liquids or of Air within the Cavity of the Thorax. By
Dr. WitttAM STOKES.

On Aneurism by Anastomosis. By R. Avams, A.M, Member of

the Royal College of Surgeons.

Abstract of a Case of deficient Development of the right Hemi-
sphere of the Brain, with Congenital Malformation of the Hip and
Wrist Joints, and Atrophy of the Members of the same Side. By
Dr. Hutton.

Description of a Case of Deformity of the Pelvis, in which the Cesa-
rean Operation was successfully performed. By G. B. KNowLEs,
MR.CS., FLS., Lecturer on Botany atthe Birmingham School
of Medicine.

Propositions concerning Typhus Fever,deduced from numerous Obser-

vations. By Dr. Perry.

On the Use of Chloride of Soda in Fever. By Roz. J.Graves, M.D.

Dr. Graves commenced a series of clinical experiments in 1832
upon the efficacy of chloride of soda in petechial and maculated
fever. He has exhibited this medium at Sir Patrick Dun’s Hospital
and at the Meath Hospital, where its effects have been witnessed by
a great number of physicians as well as pupils. The form recom-
mended is Labarraque’s solution, which is a saturated solution of
chloride of soda. ‘This was given in doses of from fifteen to twenty
drops in an ounce of camphor mixture every fourth hour. In the
commencement of fever, where there is great heat of skin and signs
of vascular excitement, its employment is contraindicated. It is
also inadmissible in cases where there is decided evidence of vis-
ceral inflammation. When the early stage of fever is past, when all
general and local indications have been fulfilled, when there is no
complication with local disease, when the patient lies sunk and pro-
strated, when restlessness, low delirium, and more or less derange-
ment of sensibility is present, when the pulse is quick, when the
body is covered with maculz or petechie, and the secretions from
the skin and mucous membranes give evident proof of what has.
been termed a putrescent state of the fluids, it is then that the chlo-
ride of soda may be prescribed with advantage. It operates, although

~ —_——

a oe — ar

Subsection of Mechanical Sciences applied to the Arts. 65

not rapidly, yet energetically, in arresting many of those symptoms
which create most alarm. It seems to counteract the tendency to
tympanitis, to correct the foetor of the excretions, to prevent collapse,
to promote a return to a healthy state of the secretions of the skin,
bowels, and kidneys; in fact, it appears admirably calculated to
meet the bad effects of low putrid fever. Its employment does not
preclude the use of wine or other approved remedies. Dr. Graves
has used it in several hundred cases of typhus, and strongly recom-
mends its employment in that disease.

Original Views of the Functions and Diseases of the Intestinal
Canal, $c. By Dr. O'BEiRNE.

On Purulent Ophthalmia. By Dr. Evory KEnneEpy.

Dr. Evory Kennedy gave a report of numerous cases of purulent
ophthalmia of infants, in which leeching, constant removal of the pu-
rulent secretion, and caustic applications, modified according to the
violence of the attack, and, in aggravated cases, the solid nitrate of
silver, applied to the interior of the lids, had proved most successful.

A notice of the curved Drill Catheter, invented by Mr. Francis
L’EsTRANGE, was presented to the meeting.

Mr. Hawks exhibited to the Section specimens of Harrington’s
patent Electrizer. — /
Abstract of Registry kept in the Lying-in Hospital of Dublin. By

Rogert Coutuins, M.D., late Master of that Institution.*

MECHANICAL SCIENCES APPLIED TO THE ARTS.
On Impact and Collision. By Eaton HopcGKinson.

Mr. Hodgkinson reported to the Section the results of certain ex-
periments made by him on impact and collision, in continuation of
those communicated to the Association in the year 1834 on the
collision of imperfectly elastic bodies. The results were,

First, That cast-iron beams being impinged upon by certain
heavy masses or balls of metal of different kinds, were deflected
through the same distance, whatever were the metals used, provided
that the weights of the masses were equal.

Secondly, That the impinging masses rebounded after the stroke
through the same distances, whatever was the metal of which they
were composed, provided that the weights were the same.

Thirdly, That the effect of the masses of different metals impinging
upon an iron beam were entirely independent of their elasticities, and
were the same as they would give ifthe impinging masses were inelastic.

Mr. Hodgkinson also gave the result of some interesting experi-
ments on the fracture of wires under different states of tension, from

* Of this and some other communications made to the Medical Section,
the titles only of which are given in our report, abstracts will be found in the
copies of the Proceedings of the Association, separately printed for the use
of the members.— Epi.

Third Series. Vol. 8. No. 43. Jan. 1836. K

66 British Association for the Advancement of Science.

which it appeared that the wire best resisted fracture and impact
when it was under the tension of a weight which, being added to
that impinging upon it equalled one third of the force that was ne-
cessary to break it.

On the Solid of least Resistance. By J. S. Russevy.

Mr. Russell was called upon to give an account of a new form for
the construction of ships, by which they should experience least re-
sistance from the water in their passage through it. A vessel of 75
feet keel and 6 feet beam had been built on this new formation,
and made the subject of very accurate experiments, from which it
appeared that this vessel, named the “ Wave”, experienced much less
resistance in passing through the water than vessels of the very finest
formation and from the best builders on the old construction.

Mr. Russell then detailed very minutely the mode of forming any
vessel on his plan when the length and breadth were given. The
peculiarity, in general terms, appears to be the formation of the en-
trance lines from parabolic ares, so as to have a point of inflection at
about one sixth part from the bow of the vessel, before which the bow
is concave externally, giving the finest possible entrance at the stern,
at an angle of contact infinitely small, and behind which the con-
vexity is external and the formation elliptical to the midship section,
after which the formation becomes wholly ellipsoidal. Mr. Russell
had been induced to consider this solid as the solid of east resistance
from a phenomenon that appeared to distinguish this form from all
others, namely, that it entered the water at the highest velocities
without breaking in the slightest degree the evenness of its surface ;
that, while at high velocities all other formations dashed the water
into spray or raised it in waves above the surface, this vessel, at ve-
locities of 16 or 18 miles an hour, appeared to give no motion to any
particles of water, excepting such as happened to lie in its path. He
considered the entrance into smooth water without ruffling the sur-
face as the criterion of minimum resistance.

Mr. Russell observed, that the form had been constructed on a
hypothetical view of the subject, viz. that the minimum force requi-
site to alter the position of any fluid particle would be that which
gave to the particle a uniformly accelerated velocity through the
former half of its path, and a uniformly retarded velocity during the
remainder; that the well-known relation of the coordinates of the
parabola accomplished this in the manner formerly explained, but
that he rested for the proof of the correctness of the theory upon
the experiments he had already adduced.

Mr. Russell then described a very simple mode of construction, by
which the ordinates of a circle or a table of sines might be used so
as, in the most elementary mechanical manner, to form a very close
approximation to the solid of least resistance ; and he concluded by
drawing the lines of a vessel of given dimensions according to the
new formation of least resistance.

On certain points in the Theory of the Construction of Railroads.
By the Rev. Dr. LARDNER and C, VIGNOLLES.

ees he ae ie

Subsection of Mechanical Sciences applied to the Arts. 67

On the Monthly Reports of the Duty of Steam-engines employed in
draining the Mines of Cornwall. By Joun Tay or, F.RS.,
Treasurer of the British Association.

Mr. Taylor observed that he had found at this and other Meetings
of the Association considerable interest to be expressed with regard
to this method of recording the actual effect produced by the con-
sumption of a given quantity of fuel, and recommended it to the
notice of engineers in general. ‘The monthly reports alluded to gave
the means of comparing one engine with another in this district;
they also afforded an historical view of the progress of improvement
in this important machine; and they had, Mr. Taylor believed,
contributed largely to that improvement, by the emulation and at-
tention excited by them in the persons who had the charge of con-
structing and managing the engines.

Mr. Taylor stated that the work done in the best engines now
employed in Cornwall by the consumption of one bushel of coal, re-
quired ten or twelve years ago the consumption of two bushels ;
that during the period of Boulton and Watt’s patent four bushels
were consumed to do the same work, and that in the earlier stages of
the employment of steam power the quantity of coal used was 16
bushels, So that by the progressive advance of improvement one
bushel had become sufficient for the ‘duty that formerly required
sixteen.

Mr. Taylor, in remarking on the importance of this subject to the
deep mines of Cornwall, stated, that the steam-engines now at work
for the purpose of draining the mines there were equal i in power to
at least 44,000 horses, and that as some doubts had frequently been
expressed as to the accuracy of the results shown by the duty re-
ports, he had compared them some time since with the accounts
of the coal actually used in some of the principal mines at different
periods, by which he found the saving of money was as great as the
reports indicated, and that their general accuracy was borne out
fully by the account books, where this was incontestably proved.

Description of a Self-registering Barometer 5c. By Prof. StEVELLY.

During the oscillations of the common barometer, when it falls, a
certain quantity of mercury is added to that already in the cistern,
which of course adds so much to its weight; on the contrary, when
it rises, mercury retires from the cistern, which thereby becomes so
much lighter than before. If, then, the tube of a barometer be fixed
firmly in its place, but the cistern be by any means so suspended as
to move downwards by equal distances for equal additions to its
weight, and to rise similarly for similar diminutions of its weight, it
is clear that a scale may be placed beside the cistern; and an index
carried by the cistern may be made to mark upon the scale a
variety of positions corresponding to the rising and falling of the
common barometer. It may be shown to any person even slightly
conversant with mathematical subjects, that the range of this scale
may be made to bear any proportion to that of the common baro-
meter. Supposing for an instant what is now stated to be accom-

K 2

68 British Association forthe Advancement of Science.

plished, it is obvious that a pencil may be so attached to the cisterm
as to rise and fall with it, and thus to mark on a properly ruled sheet
of paper, carried by clockwork across the instrument, the indications
of the barometer at the successive hours of the day; and thus a
curve representing the actual diurnal oscillations of the barometer
can be placed before the eye, and a registry kept from day to day
on separate sheets of paper. The mean curve can also be had by
making the pencil traverse, day after day, for a long period, the
same sheet of paper; for the pencil-marks will at length become
blackest and heaviest upon the parts corresponding to the mean
curve; and thus all the labour of actual observation, registry, &c.
will be avoided, and thus, too, much of the trouble of reduction, if
not all, will be saved.

Many mechanical methods of suspending the cistern will readily
suggest themselves to persons conversant with practical matters ; but
the method that is preferred by the author is by a mercurial hy-
drometer, the cistern, for the sake of stability, being suspended
underneath the hydrometer, as in Ronchetti’s modification of Nichol-
son’s hydrometer. The accompanying drawing will give an idea of
the form of the instrument; the following is the description of it.
The guide-wheels and supports are omitted.

; B the barometer tube (it may be of
ir iron) firmly fixed in its place, and dip-
| ping below into

C, the cistern, which is suspended by

F, a frame, supported by

S, the pillar or stem of

H, the hydrometer ball, which floats
in

A, a vessel firmly fixed, and contain-
ing the mercury (or other fluid) in
which the hydrometer floats.

In the description of this instrument
given to the Subsection, it was sup-
posed that the surfaces of the mercury
in the cistern and in the vessel A were
so large that the rising or falling of
the fluid in these vessels might be
neglected; also, since the instrument
is very sensible, it was supposed that
the lower part of the barometer tube
which dips into the cistern should be
rendered very small, in order to di-
minish unsteady oscillation. Also the
internal part of the barometer tube
B at the upper part, the external
part where it dips into the mercury in
the cistern, as well as the cistern and
the vessel A, at the surfaces of the
mereury in them, were all supposed to
he cylindrical. And it was then shown

Subsection of Mechanical Sciences applied to the Arts. 69

in a popular manner, that if the internal cross section of the baro-
meter tube at its upper part were made equal to the cross section of
the pillar or stem of the hydrometer, the sensibility of the instru-
ment would be too great for practice; the scale in that case would
be lengthened out indefinitely, since the hydrometer could never
sink sufficiently to attain a position of equilibrium upon a fall of the
barometer, and vice versd. But if the cross section of the stem or
pillar of the hydrometer be made twice as great as the internal cross
section of the upper part of the barometer, the rising and falling of
the cistern would be exactly equal to the rising and falling of the
common barometer ; and therefore the scale of this instrument would
then be equal to the scale of the common barometer; and between
these limits any desired scale, however long, may be obtained. A
scale shorter than that of the common barometer may also be had
by increasing the cross section of the stem of the hydrometer be-
yond the above limit ; but this is not likely to be ever desired. When
it is desirable to save expense, the hydrometer may be made to float
in water; but of course its dimensions will require to be much
greater in that case: or the cistern may be counterpoised, and a
cylinder like the stem of the hydrometer, dipping into the mercury,
may, by its varying buoyancy, be made to restore the equilibrium.

The exact mathematical formula which gives the relation of the
scale to that of the common barometer, whatever be the dimensions
of the parts of the instrument, is of the form 6h = dh' x C, where
6h is the variation of the height of the common barometer, 2h! is
the corresponding part of the scale of this instrument, and C a con-
stant depending for its value upon the dimensions of the several parts
of the instrument.

Professor Stevelly also described a very simple and cheap instru-
ment for weighing hydrometrically, the sensibility of which is very
remarkable,—a hydrometer-ball with a stem of steel wire, having
upon it one or two dots of gold, and a scale-pan attached to it, either
above as in Nicholson’s, or below as in Ronchetti’s modification of
the hydrometer. An index, or a microscope with a horizontal wire,
is attached to the side or cover of the vessel in which the hydro-
meter floats in such a way that it may be steadily and slowly raised
or lowered to mark the position of the gold-dot, instead of taking the
indications from the surface of the fluid, as in the common method.
The weight of the substance to be weighed is then had by placing
it in the seale-pan, bringing the index or wire of the microscope to
mark the position of the gold-dot, then removing the substance and
substituting for it known weights until the dot is again brought to the
same position. Since the adjustment takes place at the instant of
using the instrument, it becomes almost incapable of being deranged,
and thus a very correct balance may be had by a common apothe-
cary’s phial, with a little mercury to steady it, and a knitting-needle
pushed down through its cork, and a scale-pan placed above. Every
person knows the difficulty of adjusting the common hydrometer, and
its liability to derangement.

The same principle may be readily conceived to apply to the con-
struction of a self-registering rain-gauge.

70 British Association for the Advancement of Science.

On Vibration of Railways. By Capt. Denuam, R.N.

Capt. Denham ascertained that the vibrating effects of a passing
laden railroad train in the open air extended laterally on the same
level 1110 feet, (the substratum of the positions being the same,)
whilst the vibration was quite exhausted at 100 feet when tested ver-
tically from a tumel.

The tunnel was through a stratum of sandstone rock: the rails
laid in the open air on a substratum of 12 feet of marsh over sand-
stone rock. The method of testing was by mercury reflecting ob-
jects to a sextant. The experiments were made in the neighbour-
hood of Liverpool.

Mr. Anprew Parircuarp exhibited examples of various kinds
of apparatus constructed by him for illustrating the Polarization of
Light; and gave a brief account of his improved achromatic micro-
scope, one of which was placed upon the table.

The construction of a simple polariscope invented by Mr. Pritch-
ard was explained. The crystals to be examined were mounted in
slides and introduced between tourmalines, by which means sections of
any crystals that present themselves may be examined, and the cell
of the upper tourmaline being removeable can be employed for other
experiments. A lens was attached for condensing artificial light.

The mechanical part of the achromatic microscope produced was
constructed on the principles recently published by Dr. Goring and
Mr. Pritchard in their works on the microscope: the chief feature in
the optical part was the execution of a set of object-glasses which
admitted a pencil of light of siaty-eight degrees, free from spherical
and chromatic aberration, having the oblique pencils nearly correct
and the field of view moderately flat. Mr. Pritchard stated expressly
of this instrument, that it was the simplest that had yet been con-
structed that would accomplish all the work that might be required
of a microscope, either for general examination, dissection, or minute
investigation.

Preparations of various classes of microscopic objects in Canada
balsam were exhibited.

Mr. Hawkins explained the principle of Saxton’s locomotive Dif-
ferential Pulley ; and a mode of producing rapid and uninterrupted
travelling by means of a succession of such pulleys set in motion
by steam-engines or by horses.

Mr. CHEvERTON read a paper on Mechanical Sculpture, or the
production of busts and other works of art by machinery, and illus-
trated the subject by specimens of busts and a statue in ivory, which
were laid on the table. This machine, in common with many others,
produces its results only through the medium of a model to govern
its movements; but it has this peculiarity, that the copy which it
makes of the original is of a size reduced in any proportion, and
that it is enabled to effect this result not merely on surfaces, such as
bas reliefs, but in the round figures, such as busts and statues.

Geological Society. 71

Mr. Errrick gave an account of certain improvements proposed
by him in the Astronomical Clock for giving the pendulum a free
motion at right angles to the line of its motion, and thereby pre-
venting the tendency to acquire a circular motion by any improper
adjustment of the pendulum-spring.

He described a mariner’s steering-compass provided with two ad-
justments, whereby the card was made to point ¢rve bearings on the
horizon; the variation and local attraction being allowed for by regu-
lating the position of the needle on the card.

He also read an account of certain improvements on steam-
engines, for making available the power of the steam of high-pressure
boilers, which is below the pressure of the atmosphere, by allowing
the high-pressure steam to pass off into the atmosphere, and allowing
the steam of low-pressure to pass into a condenser through a secon-
dary slide. He gave a description of a method of securing the seams
of boilers by longitudinal instead of the present circular clenches ;
and of a machine for drilling boiler plates as rapidly as they can be
punched by the punching machine.

Mr. Rogerts exhibited a machine which renders objects visible
while revolving 200,000 times a minute.

If a firebrand be whirled, in the dark, round a centre in a plane
perpendicular to the eye of the spectator, it will present the appear-
ance of a luminous circle. From this fact it has been inferred, that
the impression on the retina made by the luminous body in its pas-
sage through every point of the circle, remains until the body has
completed a revolution. How rapidly soever the firebrand may be
made to revolve, the circle, and, therefore, every part of it, will be
distinetly visible: hence a probability arises, that at the greatest at-
tainable velocity, a perfect impression of the object in motion will
still be produced on the optic nerve, provided that the time of view-
ing such object be limited to that which is required for passing
through a small space—small, at least, with reference to the size of
the revolving body—and also that no other object be presented on
the field of vision before the former spectrum shall have vanished
from the eye; unless in the case of the same object under similar
circumstances. The former of these conditions is provided for in
machine, No. 1, in which the eye-hole is made to travel through
180 feet between every two inspections of the moving object, and
which object is made to assume a different position at each succes-
sive inspection. The latter condition is included in machine No. 2;
the object is there presented to the eye in one position only.

GEOLOGICAL SOCIETY.
Nov. 7, 1835.—The Society assembled this evening for the Session.
A paper was first read, entitled ‘A notice on the Fossil Beaks of
four extinct species of Fishes, referrible to the genus Chimera, which
occur in the oolitic and cretaceous formations of England,” by the
Rev. William Buckland, D.D., F.G.S., &e. This paper has been given
atlength in the present Number, at p. 4.

72 Geological Society.

A paper was next read, “ On the recent discovery of Fossil Fishes
( Palgoniscus catopterus, Agassiz,) in the new red sandstone of T yrone,
Ireland ;"’ by Roderick Impey Murchison, Esq., V.P.G.S.

A Sinall specimen of new red purtachenved presenting the first im-
pressions of fishes found in this formation in the British Isles, having
been exhibited before the Geological Section of the British Association
at the late meeting in Dublin, Mr. Murchison, in company with Prof.
Sedgwick, Lord Cole, and Mr. Griffith, visited the spot where it had
been obtained.

The quarry is at Rhone Hill, in the parish of Killyman, about three
miles east of Dungannon. ‘The new red sandstone in which it is ex-
cavated is a prolongation of the deposit which occupies large tracts
in the county of Antrim, and extends into this part of Tyrone, where
it surrounds a small, slightly productive coal-field, but reposes for the
greater part upon mountain Jimestone. The eastern flank of the di-
strict is covered by a vast thickness of clay, containing lignite, the
exact age of which is not known; and the surface generally is very
much overlaid by loose detritus, consisting of sand and gravel, derived
from the adjacent formations. Large blocks of syenite and green-
stone, referrible to a northern origin (Antrim), are scattered here and
there.

The beds of new red sandstone exposed in the quarry dip about 15°
to the N.N.E., and consist, in the upper part, of red and green marls,
passing down into a dark red, thickly bedded, siliceous sandstone,
with a few irregular, highly micaceous way-boards of a deep purple.
colour. The surface of some of the beds exhibits ripple-marks. The
quarry, which is the property of Mr. Greer, is from 25 to 30 feet deep,
and the fishes are found only in the bottom beds, but are in great
abundance *,

Dr. Agassiz afterwards gave a systematic enumeration of the fos-
sil fishes which he has found in English collections. He commenced by
detailing the general results of his researches, from which it appears,
that the discovery in England of three hundred new species has
corroborated the laws of development which he had previously de-
termined in the succession of these animals during the different
changes which our globe has undergone, with the exception of the
discovery in the chalk of two species belonging to two genera which
he had before observed only in the oolitic series, and of a species of
one of those genera in the lower tertiary strata.

The secondary systems (terrains) of England are the richest in fos-
sil fishes ; and Dr. Agassiz stated that the number of specimens which
he has seen in English collections is astonishing. The species which
he has determined are about 400; but the specimens too imperfect
to be described, at present, announce the existence of a still greater
number.

Their geological distribution presents the following details:

In the Silurian system of Mr. Murchison there are five or six spe-
cies which exhibit the first appearance and organization of this long

* A slab, presented to the Geological Society by Mr. Greer, exhibits, on
a surface not exceeding two feet square, above 250 fishes.

Geological Socicty. 73

series of vertebral animals, the species of which become more and
more numerous, and more and more diversified, as well in their forms
as in the details of their organization.

The old red sandstone, including the Caithness schist and the Gam-
rie deposit, contains twenty species.

In the coul measures there are fifty-four species ; in the magnesian
limestone sixteen.

The oolitic series is particularly rich in ichthyolites, the number of
species from the lias to the Wealden inclusive being one hundred
and fifty.

The greensand and chalk are also very rich in fossil fishes, and
even much richer than their equivalents on the Continent. The num-
ber of English species is fifty.

In the London clay the species perfectly determined are about fifty,
but it is certain, from the fragments preserved in different collections,
that this formation incloses the remains of a much greater number.
M. Agassiz stated that the London clay, particularly in Sheppey, will
be, for a long time, an inexhaustible mine.

The crag contains five or six species peculiar to it, and belonging
to genera which do not inhabit our northern seas.

As an example of what remains to be done in the study of fossil
fishes, and of the importance of these researches to zoology and geo-
logy, M. Agassiz afterwards described two singular genera found in
the lias. One is the animal which has been described under the name
of Squalo-raia, discovered at Lyme Regis ; the other a new genus,
called by M. Agassiz Gyrostris mirabilis, and is probably the largest
known fish. This fossil was discovered at Whitby; but there have
hitherto been found only some detached bones of the head, of the
branchial arcs, and some portions of vertebra and fins: traces of the
same fish have been recently observed at Lyme Regis.

Nov. 18.—A letter was first read from Dr. Pingel of Copenhagen
to the President, containing a notice of some facts showing the gradual
sinking of part of the west coast of Greenland.

The first observations which led to the supposition that the west
coast of Greenland nad subsided, were made by Arctander between
1777 and 1779. He noticed, in the firth called Igalliko (lat. 60° 43’
N.), that a small, low, rocky island, about a gun-shot from the shore,
was almost entirely submerged at spring tides, yet there were on it
the walls of a house 52 feet in length, 30 feet in breadth, 5 feet thick,
and 6 feet high. Half a century later, when Dr. Pingel visited the
island, the whole of it was so far submerged that the ruins alone
rose above the water.

The colony of Julianahaab was founded at the mouth of the same
firth in 1776; and near a rock, called the Castle by the Danish co-
lonists, are the foundations of their storehouse, which are now dry
only at very low water.

The neighbourhood of the colony of Frederickehaab (lat. 62° N.),
was once inhabited by Greenlanders ; but the only vestige of their
dwelling is a heap of stones, over which the firth flows at high water.

Near the well-known glacier which separates the district of Fre-

Third Series. Vol. 8. No. 43. Jan. 1836. L

74 Geolog:cal Soctety.

derickehaab from that of Fiskenass, is a group of islands called
Fulluartalik, now deserted ; but on the shore are the ruins of winter
dwellings, which are often overflowed.

Half a mile to the west of the village of Fiskenass (lat. 63° 4’ N.),
the Moravians founded, in 1758, the establishment called Lichtenfeld.
In thirty or forty years they were obliged once, perhaps twice, or
move the poles upon which they set their large boats, called Umiak,
or Women’s boats. The old poles still remain as silent witnesses,
but beneath the water.

To the north-east of the mother colony, Godthaab (lat. 64° 10’ N.),
is a point called Vildmansnass by St. Egede, the venerable apostle
of the Greenlanders. In his time, 1721—1736, it was inhabited by
several Greenland families, whose winter dwelling remains desolate
and in ruins, the firth flowing into the house at high tide. Dr. Pin-
gel says that no aboriginal Greenlander builds his house so near the
water's edge.

The points mentioned above the writer of the letter had visited ;
but he adds, on the authority of a countryman of his own highly de-
serving of credit, that at Napparsok, 10 Danish miles (45 miles En-
glish) to the north of Ny-Sukkertop (lat. 65° 20' N.), the ruins of
ancient Greenland winter houses are to be seen at low water.

Dr. Pingel is not aware of any instance of subsidence in the more
northern districts ; but he suspects that the phenomenon reaches at
least as far as Disco Bay, or nearly to 69° north lat.

Some notes by Capt. Fitzroy, R.N., read at a Court Martial at
Portsmouth, Oct. 19th, 1835, on Capt. Seymour and his Officers
for the loss of His Majesty’s Frigate Challenger, wrecked on the coast
of Chili, near the port of Conception, and communicated to the Pre-
sident by Capt. Beaufort, R.N., Hon Mem. G.S., were then read.

These notes refer to the effects produced by the earthquake of Feb.
1835, in the currents on the coasts of Chili, from the Island of Mo-
cha to the parallel of Conception. Capt. Fitzroy also mentions that
the island of Santa Maria was elevated ten feet.

A letter dated Valparaiso, 22nd of March 1835, from R. E. Alison,
Esq., addressed to the President, on the earthquake of Chili of the
20th of February 1835, was then read.

The earthquake began at quarter past 11 a.m. by a gentle heaving .
or undulation of the earth ; but the motion increased in a few seconds
to so great a degree that no person could stand. It destroyed the
cities of Conception and Chillan, with the ports of Talcahuano and
Maule, as well as above twenty smaller towns, and animmense num-
ber of country houses. It was felt to the southward as far as the In-
dian territory opposite the island of Chiloe ; to the northward be-
yond Copiapo ; at Mendoza on the east of the Andes; by the crew of
a ship 100 miles to the westward of the coast, and at Juan Fernandez
300 miles from it.

At the port of Talcahuano the same phenomena occurred which ac-
companied the destruction of Pencoin 1730 and 1751. Forty minutes
after the first shock the sea suddenly retired so far that part of the
bottom of the Boca chica, the smailer or southern entrance of the bay,

Linnean Society. 75

could be seen ; but the sea afterwards returning through the same
channel with a great bore, flowed 20 feet over the town, carrying
everything before it. This phenomenon was repeated three times.
Mr. Alison says that the sea was reported to have receded, or rather
the land to have risen, 2 or 3 feet, a difference having also taken place
in the soundings in the bay; and that a rock, which was invisible pre-
viously to the earthquake, was afterwards near the surface.

Large fissures are stated to have been made in the earth, and water
to have burst from some of them: the earth is also said to have opened
and closed ; and near Los Angeles several hills to have disappeared,
and others to have opened and vomited steam and black smoke. The
harbour of the island of Santa Maria was destroyed, and the sea retired
between 300 and 400 yards, while the reefs which surrounded the
greater part of the island are said to have entirely disappeared.

At the island of Juan Fernandez phenomena occurred similar to
those which accompanied the destruction of Talcahuano. About a
league from the shore the sea appeared to boil, a high column of water
was thrown into the air, when the sea retired so far that a number of
old anchors and brass guns became visible ;_ but it soon returned with
great violence, carrying off all the houses of the convicts. A volcano
also burst forth at the point where the sea was first agitated. The
brig Glanmalin was in the latitude of Talcahuano, and about 100 miles
to the westward of it, at the time of the earthquake, when the crew
felt a shock as if the vessel had struck upon a rock.

Mr. Alison also mentions the existence near Valparaiso of the re-
cent marine shells 1400 feet above the level of the sea, and of recent
marine shells being dug near Conuco for the purpose of making lime.
In the bay of Valparaiso, he says, a rock which in 1817 could be passed
over in a boat, is now dry, except at spring tides.

LINNEAN SOCIETY.

Nov. 17.—A notice, by Mr. White was read, ofan individual of the
Great Black Woodpecker (Picus martius of Linnzus,) having been
shot in 1834 at Billingford, near Scole Inn, Norfolk. The stuffed
specimen is in the possession of Mr. Drake, a farmer of that place.
The bird was shot in a moist natural wood, where the Rhamnus Fran-
gula and Viburnum Opulus abound. Another of the same species was
seen at the same time.

The conclusion of Mr. Don’s “Descriptions of Indian Gentianee”
were then read. .

Among the numerous families which compose the class of Dicoty-
ledonous plants, there is perhaps none so equally and generally dis-
tributed over the surface of the globe as the Gentianee, extending
almost to the extremities of both hemispheres, and occurring in every
intermediate region wherever the elevation of the land and other local
circumstances favour their development. By a comparison of the
Floras of different countries they appear to constitute the proportion
of about | to 83 of the phenogamous vegetation. By the indefatigable
researches of Dr. Wallich and Mr. Royle, the number of species. of
this order belonging to the Indian Flora has been more than doubled,
and they now amount to about 50. Of the 13 genera into which

L2

76 Linnean Society.

they have been distributed, Carscora, Exacum, Slevogtia, Crawfurdia,
Agathotes, and Ophelia are exclusively Indian, and the remaining 7
are common to the European and Northern Asiatic Floras. Of these
50 species, 33 belong to the Alpine Flora, which, in 3500, the number
at which the phenogamous plants of the Flora of Northern India may
be estimated, will give a proportion equal to that above stated. ‘The
author has confined himself in this paper to the description of the
species found by Mr. Royle. We subjoin the new genera and species :

Gen. 1. Gentiana. Borck. Brown.

1. G. contorta, annua; floribus solitariis, corolla infundibuliformi 5-loba:
lobis lineari-oblongis obtusis zestivatione convolutis, dentibus calycinis
lanceolatis acuminatis, foliis ellipticis obtusis 5-nerviis subsessilibus.

Gen. 2. Preumonantae. Schmidt.

1. P. Kurroo, caulescens, subuniflora; dentibus calycinis elongatis subulatis,
corolla campanulata : lebis acutis, foliis obtusis; radicalibus elongato-
lanceolatis; caulinis linearibus.

2. P. depressa, subacaulis, ceespitosa, uniflora; dentibus calycinis ovato-
lanceolatis mucronatis, corolla campanulata : lobis integerrimis aristatis,
foliis lanceolatis mucronatis margine scabris ; surculinis obovatis.

Gen. 3. Ertcata. Renealm.

1. FE. capitata, caulescens, simplex; foliis ovatis, floribus aggregatis, den-
tibus calycinis ovatis mucronatis recurvis, corolla lobis ovatis obtusis :
sinubus crenatis.

2. E. argentea, acaulis; foliis calycibusque lanceolatis mucrenatis condu-
plicatis recurvis margine scarlosis, floribus fasciculatis, corolla lobis
Ovatis acuminatis.

3. E. marginata, caulescens, ramosa ; foliis lanceclatis mucronulatis planis
margine cartilagineis, floribus fasciculatis, dentibus calycinis ovato-
lanceolatis mucronatis erectis, corolle lobis obtusis: sinubus acutis.

4. E. decemfida, caulescens, ramosa; dentibus calycinis subulatis mucronatis
rectis, corolla lubis lanceolatis acuminatis: sinubus bidentatis, foliis
radicalibus ovatis mucronatis maximis ; summis subulatis.

5. E. pedicellata, caulescens, ramosissima ; dentibus calycinis lanceolatis
mucronatis revolutis, corolla lobis ovatis acuminatis : sinubus integris,
foliis lanceolatis acuminatis, capsula longé stipitata.

6. E. canaliculata, caulescens, erecta, ramosa; segmentis calycinis cuneatis
mucronatis, corollz lobis ovatis acutiusculis, foliis ovato-lanceolatis ob-
tusis margine scabris.

Gen. 4. Euvrytuaria. Renealm.

1, E. coronata, breviter caulescens; floribus aggregatis, corolla 10-loba :
sinubus lobis subzequalibus ovatis uniformibus, foliis lanceolatis acutis
margine cartilagineis.

2, E. pedunculata, caulescens, ramosa, diffusa; pedunculis elongatis fili-
formibus unifloris, corolla 5-fida calyce ter longiore, laciniis calycinis
ovatis obtusiusculis.

3. E. carinata, caulescens, simplex; foliis lanceolatis mucronatis carinatis,
Horibus fasciculatis, corolla 10-loba: lobis lanceolatis acuminatis ; sinu-
um duplo brevieribus argute denticulatis.

Gen. 5. Craweurvia. Wall.

1. C. fasciculata,
2, C. speciosa,

oe 7

_
a

Linnean Society. i

Gen. 6. Swertia. L.

1. S. speciosa, foliis oppositis connato-vaginantibus elliptico-oblongis acu-
minatis 7-nerviis, floribus racemoso-paniculatis, corollz segmentis acu-
minatis : glandulis connatis.

2. S. petiolata, foliis oppositis petiolatis oblongis obtusis 5-nerviis, floribus
racemoso-paniculatis, corolla segmentis obtusis: glandulis distinctis
filamentoso-ciliatis.

3. S. alternifolia, foliis alternis ! elliptico-oblongis acuminatis 7-nerviis basi
vaginantibus, floribus racemoso-paniculatis, corolla segmentis ellipticis
obtusis: glandulis orbiculatis contiguis.

4. S.cuneata, foliis oppositis petiolatis spathulato-oblongis obtusis 5-nerviis,
floribus racemosis, corolla segmentis obtusis : glandulis lineari-oblon-
gis subremotis filamentoso-ciliatis.

5. S. cerulea, floribus subsolitariis, ecrolle segmentis ovatis mucronulatis :
glandulis linearibus distantibus, foliis inferioribus spathulatis petiola-
tis ; superioribus calycibusque lanceolatis obtusiusculis.

Gen. 7. AGATHOTES.

1. A. Chirayta, caule tereti, foliis ovato-lanceolatis, foveis nectariferis ob-
longis distinctis : squamulis margine capillaceo-fimbriatis.

2. A. alata, eaule tetragono alato, foliis ovatis, fovea nectarifera orbicu-
lata: squamula rotundata fimbriata.

Gen. 8. OPHELIA.

1. O. angustifolia, floribus 4-fidis, foliis petiolatis lineari-lanceolatis agutis,
segmentis calycinis linearibus mucronulatis, corollz laciniis ovatis acu-
minatis calyce brevioribus.

2. O. pulchella, floribus 4-fidis, foliis lanceolato-linearibus acutis, segmen-
tis calycinis lanceolatis acuminatis, corolla laciniis ovatis mucronu-
latis calyce longioribus, caule tetragono.

3. O. paniculata, floribus 5-fidis, foliis linearibus scabris margine revolutis,
petiolis ciliatis, segmentis calycinis lanceolatis acuminatis, corollze
laciniis ovato-lanceolatis acuminatis calyce vix longioribus, caule
tereti.

4. O. purpurascens, floribus 5-fidis, foliis lanceolatis acuminatis 3-nerviis
scabris, petiolis ciliatis, segmentis calycinis lanceolatis mucronatis, co-
rollz laciniis ovato-lenceolatis acuminatis basi bituberculatis calyce lon-
gioribus, filamentis basi connatis, caule teretiusculo.

5. O. cordata, floribus 5-fidis, foliis sessilibus cordatis acutis 5-nerviis, seg-
mentis calycinis ovato-lanceolatis acuminatis, corolla laciniis oblongis
obtusiusculis calyce brevioribus.

6. 0. lurida, floribus 4-fidis, foliis superioribus cordatis acutis amplexicauli-
bus, segmentis calycinis lineari-lanceolatis mucronulatis, corolla laci-
niis ovatis acuminatis calyce longioribus.

Gen. 9. Hatenta. Borck.
1. H. elliptica, corollis campanulatis 4-fidis calcaribus filiformibus breviori-
bus, laciniis calycinis obtusis abbreviatis, foliis ellipticis obtusis 5-nerviis ;
inferioribus petiolatis.

Gen. 10. Enyrun®a. Renealm.

1. Z£. Roxburghii, floribus pedunculatis corymbosis, corolla laciniis lanceo-
latis : tubo calycis longitudine, foliis superioribus jinearibus 3-nerviis,
caule quadrangulo.

78 Cambridge Philosophical Society:—Sir John F. W. Herschel

Gen. 11. Carscora. Lam. Brown.
1. C. diffusa.

2. C. decussata.
3. C. pusilla.

Gen. 12. Exacum. L. Brown.

1. E. pedunculatum.
2. E. tetragonum.

Gen. 13. Stevoetia. Reichend.
1. S. verticillata.

_—_-—_—.

CAMBRIDGE PHILOSOPHICAL SOCIETY.

At the anniversary meeting on Friday, November 6th, 1835, the
following officers were elected for the ensuing year :

Dr. Clark, Trinity College, President ;— Professor Cumming, Tri-
nity College ; Professor Sedgwick, Trinity Coliege ; Dr. F. Thackeray,
Emanuel College, Vice-Presidents ;— Kev. G. Peacock, Trinity Coi-
lege, Treasurer :—Rev. Professor Henslow, St. John’s College; Rev.
W. Whewell, Trinity College; Rev, J. Lodge, Magdalen College,
Secretaries ;—W. Hopkins, Esq., St. Peter’s College ; Rev. J. Hymers,
St. John’s College; Dr. Haviland, St. John’s College; Rev. J. J.
Smith, Caius College; Rev. S. Earnshaw, St. John’s College, Old
Council ;—Rev. L. Jenyns, St. John’s College; Rev. R. Murphy,
Caius College ; Rev. A. Thurtell, Caius College; C. C. Babington,
Esq-, St. John’s College; Rev. H. Philpott, Catherine Hall, New
Council.

November 16.—After various presents of books and objects of
natural history had been announced, a Memoir was read by the
Rev. R. Murphy, ‘On the Resolution of Equations of Finite Differ-
ences.

Extracts were then read of letters from Sir J. Herschel to the Rev.
W. Whewell, containing various meteorological observations, and
especially some tending to show that the height of the barometer at
the equator is less by about a quarter of an inch than it is at twenty
or thirty degrees from it.

The following are a portion of the extracts here referred to :

««The barometer certainly has a permanently and very decidedly
lower mean ievel at and near the line. The strong upward current
due to the circulation of the trades can alone account for this. Of
the general fact I have no doubt, and however difficult it is to observe
the barometer on shipboard, from the unusual quietness of our pas-
sage, I think I can come pretty near to its true difference from that
in our latitudes. The depression at the equator below that in lat.
20° may I think be stated at 0'2 nearly.

«<These are the results of a series of barometrical observations,
made at my request by Sir E. Ryan, in his voyage to Calcutta from
this place. The barometer is reduced to 32° F., and to the Royal
Society's Standard, by careful comparison with my Troughton’s ba-
rometer,

on the Height of the Barometer in different Latitudes. 79

Mean observed
Latitude corre-
sponding.

Limits of the Zone of Lati- Mean observed
tude N. and S. Pressure.

in.

‘ 29-821
equatorial zone ..
Lat. 5° to 15°, mean of :

N. and S. zones .. eae)
Zones 15° to 25° lat... 30:030
Zones 25 to35 .... 30°125
Zones 35 to40 .... 29-934

Lat. 5° N. to 5° S., the ;

“The following set of observations (made with no care, and with a
bad barometer,) by Mr. MacHardy, surgeon of the Mountstewart El-
phinstone, in its last voyage homewards, at my request, also confirm
the equatorial depression :

No of M bserved M bserved
vie eet a ee Degree
in.
Dat OL tO OY Sa, a. 8 29°821 | ea.
Best Dh Stee, « 5 29-802 9 20
1d COL ZD aiec aire 6 29:960 19 41
23 COLO OM cee teal O 30-085 31720

** Not having Mr. MacHardy’s zero, I have made his equatorial re-
sult correspond to Sir E. Ryan’s, by addition of a constant (+ 0-188).
Sir E. Ryan’s depression is greater; Mr. MacHardy’s about the same
which I first assigned (3 inch) from my own observations in my voyage
out.”

Extracts were also read of letters from C. Darwin, Esq., of Christ
College, to Professor Henslow, containing an account of the geolo-
gical phenomena of some parts of the Andes,

Nov. 30.—Various presents were announced, and a paper by Pro-
fessor Wallace of Edinburgh was read, containing geometrical theo-
rems and formule, particularly applicable to some geodetical pro-
blems.

Afterwards Professor Airy stated his views and the results of his
observations with reference to the supposed analysis of the solar
spectrum into red, yellow, and blue, by Sir David Brewster, which
supposition he conceived to be unfounded. Professor Airy, Mr. Roth-
man, Mr. Peacock, and Mr. Power then gave an account of their ob-
servations of the Aurora Borexlis of Nov. 18th.

Dec. 14.—A communication by Mr. Potter, of Queen’s College,
was read, containing an Explanation of the Rainbow on the doctrine
of Interference, and referring especially to the Supernumerary Bows
often seen within vivid displays of the rainbow, near its summit. It
was shown that such additional bands would accompany the primary
bow if the drops were of approximately equal size, and that the cir-

So Intelligence and Miscellaneous Articles,

cumstances usually observed would be accounted for by supposing the
rain-drops of the diameter of 1-72 of an inch. ‘The considerations
account for the supernumerary bows being seen near the summit of
the bow only, since the drops, as they fall lower, coalesce, and be-
come larger; and the white fog-bows, which are often seen, would
result from very minute drops, of the diameter perhaps of one thou-
sandth of an inch,

Afterwards a communication was also read from C. Darwin, Esq.,
containing a notice that animals (lizards, &c.) which are oviparous in
certain districts of South America, as they are in this country, are
viviparous in the province of Mendoza, which he visited. Mr. Dar-
win also gave an account of red snow observed by him in the road
from St. Jago de Chili to Mendoza, by the Portello pass, and of a
microscopical examination of the substance.

XV. Intelligence and Miscellaneous Articles.

ON THE ANALYSIS OF GERMAN SILVER, AND THE SEPARATION
OF ZINC FROM NICKEL, &c. BY MR. JOSEPH D. SMITH.

ISHING to ascertain in what proportions the copper, zine, and

nickel were combined in a specimen of German silver, or pak-
fong, an alloy which has within a few years been extensively employed
as a substitute for silver plate, I referred to Rose's Analytical Chemis-
try, in which I find it stated, that when a solution of potash or soda is
added to one containing the oxides of nickel and zinc, their separa-
tion is by no means completely effected, a great excess of alkali not
redissolving the whole of the oxide of zinc, even when boiled; he
therefore directs the oxides to be converted into chlorides, and then
to volatize the chloride of zinc ; but the manipulation in this process
is of so complicated a nature and requires such numerous precau-
tions to ensure accuracy, that it is quite unsuited to any but the most
experienced and skilful analysts.

Among many of the experiments performed I tried to discover a sim-
pler method than that recommended by Rose: there was one which I
made to ascertain to what extent the oxide of zinc was soluble in soda
or potash after precipitation in mixture with oxide of nickel ; for if the
method would give results correct within 3 or 4 per cent., it would
have answered my purpose sufficiently well: therefore I took 20 grains
of zinc and 30 grains of oxide of nickel, dissolved them in muriatic
acid, and having largely diluted the solution, boiled it for half an
hour with four times as much soda as it took to precipitate the oxides.
The precipitate when dried and ignited weighed 46°4 grains, show-
ing that 16-4 grains of oxide of zinc were precipitated with the 36
grains of oxide of nickel. Thus the results obtained by the use of
caustic alkali are as incorrect in this instance, or even more so, than
when this process is employed to separate copper from zinc, the un-
fitness of which method was pointed out by Mr. Keates in a paper on
the Analysis of Brass (Ann. of Philosophy, vol. xix.), and he at the
same time gave directions for the performance of its analysis. Although
the results obtained by the employment of his process are sufficiently

Intelligence and Miscellaneous Articles. 81

correct, yet it may be advantageously superseded by passing a current
of sulphuretted hydrogen gas through the solution of the mixed metals
made strongly acid, separating the bisulphuret of copper, and after
heating the solution to expel the excess of sulphuretted hydrogen, the
zinc may be precipitated by carbonate of soda. Another experiment,
in which the process recommended by Mr. Phillips for separating oxide
of cobalt from oxide of nickel by adding a solution of potash to an
ammoniacal one of the mixed metals, was tried with equally unsa-
tisfactory results, for from 20 grains of zinc and 30 grains of oxide
of nickel a precipitate was thrown down from an ammoniacal solution
by potash, weighing after ignition 48 grains, giving 18 grains of oxide
of zinc mixed with 30 grains of oxide of nickel.

After many other methods, of which it will suffice to say that they were
all unsuccessful, I was led to try the effect of sulphuretted hydrogen
gas upon the salts of nickel and zinc, when solutions of them, pre-
viously neutral, are acidified by oneof the weaker acids, and which
acid should likewise form soluble salts with both metals. Pursuing
this idea, | mixed a little acetic acid with a neutral solution of zinc,
and also with a neutral solution of nickel, and passed a current of
sulphuretted hydrogen through both the solutions: in the solution of
nickel no precipitation took place, but in that of zinc an abundant
white precipitate fell ; and by passing excess of the gas through the
solution, the whole of the zinc was precipitated as a sulphuret. I
then made an experiment to determine whether it was possible to
analyse German silver by passing sulphuretted hydrogen through its
solution, differing in its acidity, both as regards the acid and degree
of acidity at different times, according to the nature of theg precipi-
tate desired, whether copper or zinc ; the results obtained were very
satisfactory,

245 grains of copper, 12 grains of zinc, and 20 grains of oxide of
nickel were dissolved in nitromuriatic acid; the solution, strongly
acidified with muriatic acid, was diluted with about a pint of water;
a current of sulphuretted hydrogen gas was then passed through the
Solution until all the copper was precipitated; the bisulphuret of
copper formed having been well washed, was acted on by nitric acid,
which dissolved the copper and left some sulphur ; after the separa-
tion of the latter, the solution of copper was boiled with caustic soda
to precipitate the peroxide, which after ignition weighed 30°4=24:3
grains of copper. The solution containing the zinc and nickel was
carefully evaporated to dryness, to expel the excess of acid, and the
residue dissolved in water acidulated with one fluid ounce of strong
acetic acid sp. gr. 1:0691, and warmed to assist the action : when this
was effected, the solution was diluted to about a pint, and a stream
of sulphuretted hydrogen gas was passed through it until the gas was
in excess ; a dingy white precipitate of sulphuret of zinc fell, which
weighed 18 grains = 12 grains of metallic zinc.

The remaining solution containing the nickel, after being heated
to expel the sulphuretted hydrogen, was decomposed by caustic soda ;
this gave hydrate of nickel, which when reduced to protoxide by strong
ignition, weighed 20°1 grains. In this experiment there was a loss

Third Series. Vol. 8. No. 43. Jan. 1836. M

82 Intelligence and Miscellaneous Articles.

of 0°2 grain of copper and a surplus of O°1 grain of oxide of nickel ;
errors so small that they are evidently those of manipulation and not
owing to any defect in the process followed.
70 grains of German silver gave by the above process :
Goppersros sees a. saa
DIMER TUG Lo stelle s cls PD

Nickelig? 35 B28 /s.92 thee, Sse
Gobaltht, cae. Sudeep f.9 234
70:2

There appears to be a larger proportion of copper in this than is
generally met with in German silver, for only one out of four alloys,
the composition of which, on the authority of Gersdorff, is given by
Bourchardat (Cours de Chimie, 1* partie, page 289), contains as
large a proportion of copper as the specimen | analysed, and to it
may be attributed the very yellow shade which this alloy possessed ;
its chief advantage over many others being what is technically called
* dipping well.’

The same method may doubtless also be employed to separate
manganese and cobalt from zinc, for solutions of the former metals,
when acidified by acetic acid, are not precipitated by sulphuretted
hydrogen gas.

St. Thomas’s Hospital,

December 1835.

ACTION OF MUSHROOMS ON ATMOSPHERIC AIR.

M. Marcet subjected known quantities of mushrooms to the action
of oxygen, azote, and atmospheric air under graduated receivers; and
having left them for a certain time, and ascertained the alteration
both in the volume and nature of the gases; the conclusions at
which he arrived, after performing numerous experiments, are the
following:

Ist. That mushrooms produce very different effects upon atmo-
spheric air from those which result from the action of green plants
under similar circumstances. They vitiate the air very readily, either
by absorbing its oxygen to form carbonic acid gas at the expense of
the carbon of the vegetable, or by disengaging carbonic acid ready
formed.

2nd. That the modifications which atmospheric air suffers by the
contact of mushrooms in a vegetating state are the same day and
night.

3rd. That if fresh mushrooms are suffered to remain in pure oxygen
gas, a large portion of the gas disappears in a few hours. One part
of it combines with the carbon of the vegetable to form carbonic acid
gas, while another portion is fixed in the vegetable, and is replaced
by azotic gas liberated from the mushrooms.

4th. That fresh mushrooms, by remaining for some hours in azotic
gas, produce but little change in it ; a small quantity of carbonic acid

Intelligence and Miscellaneous Articles. 83

is disengaged, and a very minute portion of azote is absorbed.—
Journal de Chimie Médicale, Oclobre 1835.

_—

ALDEHYD—A NEW COMPOUND.

This substance, composed of hydrogen, carbon, and oxygen, was
discovered by M. Liebig ; it was procured by distilling with a gentle
heat a mixture of,

Alcohol (80 per cent. real) ...... 4 parts
NOEED at. « Cet oles MiieEY haeieis on, ote 4 do.
BSPNBCU ACAD occ cic cea re cba ae oie a 3:2 6 do.
Peroxide of manganese ......... 6 do.

Aldehyd, mixed with alcohol and some other products, comes over, and
some carbonic acid is disengaged. As the new product is extremely
volatile, the receiver must be kept very cool to prevent the great loss
of it which would otherwise occur. When about six parts have been
distilled, they. are to be withdrawn and redistilled, mixed with an
equal weight of well-dried chloride of ealcium, from a retort in a salt-
water bath ; when three parts have come over, these are to be again
distilled with an equal weight of chloride of calcium, and then one
part and a half, which is aldehyd, completely free from water, and
partly so from alcohol and ether, is to be distilled. To this aldehyd
its volume of zther is to be added, and ammoniacal gas is to be passed
through it to saturation, taking care to surround the vessel with cold
water, on account of the great heat disengaged. It is requisite to
place a safety bottle between the vessel from which the ammonia is
evolved and that which contains the aldehyd and ether, in order to
prevent the passage of vapour of the aldehyd into the apparatus used
for disengaging the ammonia, the absorption of this latter gas being
so extremely rapid, that it would be impossible to prevent its rise.
As the absorption of the ammoniacal gas proceeds, the liquor becomes
turbid, and numerous transparent colourless crystals are precipitated,
which are a compound of ammonia and aldehyd; these are to be
purified by two or three washings with ether ; they are then to be
dissolved in an equal weight of water, and to the solution is to be
added a mixture of three parts of sulphuric acid and four of water.
At a gentle heat the aldehyd distils with brisk effervescence, and the
operation ought to be stopped as soon as the water in the bath begins
to boil ; the aldehyd comes over mixed with water, and is to be re+
distilled with an equal volume of chloride of calcium in large pieces ;
surrounding the apparatus carefully with cold water, on account of
the heat generated by the union of the aldehyd and chloride: tne
product is to be again distilled from a salt-water bath with chloride of
calcium in powder, and the aldehyd has then the following properties :
it is liquid, colourless, transparent ; its odour is ethereal and suffoca-
ing, and its specific gravity is 0°790; it boils at 71+24 Fahr.; it combines
with water in all proportions, much heat being evolved ; if chloride of
calcium be added, the aldehyd separates and floats on the surface ; it
combines in the same way with alcohol and with ether ; its solutions
produce no change on vegetable blue colours ; it is very inflammable,
burning with a blue flame ; if it be kept in a bottle containing air, it
M 2

84 Intelligence and Miscellaneous Articles.

decomposes it ; absorbs the oxygen and becomes very concentrated
acetic acid. Phosphorus, iodine and sulphur are dissolved by this
fluid, and much heat is given out during its combination with bro-
mine and chlorine, and hydrochloric and hydrobromic acids are formed,
and it appears then to be converted into dromaland chloral. Nitric
acid, when heated with aldehyd, decomposes it ; nitric acid [oxide ?]
and nitrous acid being disengaged. By the action of heat it is con-
verted into a yellow turbid fluid, cn the surface of which a resinous
substance of a red brown colour appears, so elastic that it may be
drawn out into long filaments; this substance is called by M. Liebig,
resin of aldehyd ; long prismatic crystals are formed in aldehyd kept
in bottles.

These crystals are but slightly volatile ; they do not freeze at
212°; they sublime in very brilliant white transparent needles, and
they are hard and easily pulverized ; they are inodorous, combustible,
nearly insoluble in water, but dissolved by alcohol and ether. M. Lie-
big inquires whether these crystals are produced by the absorption
of oxygen, and he has not decided the question. After the formation
of these crystals, the aldehyd contains another soft (mow) volatile liquid,
which bears a great resemblance to acetal.

Aldehyd is composed of

4 atoms carbon...... 305°748......+. 55°024
S atoms hydrogen.... 49°918...... . $983
2 atoms oxygen...... 200;000. ...< .. »» 35°993

555°666 100-000

Journal de Chimie Médicale, Novembre 1835.

ON THE PROPERTIES OF TELLURIUM. BY BERZELIUS.

When tellurium is fused in a glass vessel containing hydrogen, and
it is allowed to cool slowly, a very shining regulus is obtained, re-
sembling burnished silver. The surface in contact with the glass is
a perfect mirror. The other surface is covered with a crystalline ve-
getation, perfectly analogous to that which is formed when a solution
of muriate of ammonia is dried upon a glass plate : the crystallization
appears to appertain to a regular system; but when the regulus is
broken and the angle of the crystallized surface is measured, it is
found to be incompatible with a regular system. If the metal be
fused in a cupel in a sand-bath it presents crystals, the form of which
is determinable.

Tellurium is not in the slightest degree malleable; it may be re-
duced to the finest powder, so as to entirely lose its metallic lustre. If
this powder be sprinkled with water, it is covered with a grey, brilliant,
metallic pellicle, which it is difficult to sink in water. In this respect
it resembles the powder of sulphur, selenium, and silicon.

The fusing point of tellurium is such as to soften glass too much
to retain it. If it be heated in glass to full redness, the body of the
retort is filled with a yellow-coloured gas resembling chlorine; some

Intelligence and Miscellaneous Articles. 85

small drops of tellurium are deposited in the neck of the retort, which,
however, do not appear to increase, although the red heat be con-
tinued for several hours. In the distiliation of tellurium in hydrogen,
already mentioned, there are formed at the place where the cold gas is
in contact with the vapour of tellurium, long, flat, crystalline needles ;
they are not sufficiently wide and thick to allow of the determination
of any angle. These crystals are also found, but in smaller quantity,
in the places at which the gaseous mixture goes out from the hottest
parts of the tube. If tellurium be strongly heated in a covered cru-
cible, it gives out when uncovered a peculiar disagreeable odour,
different from and much weaker than that of the oxide of selenium.
M. Magnus has already noticed this fact. On cooling, tellurium con-
tracts very much; and if the surface solidifies faster than the interior,
so that it can support atmospheric pressure, cavities containing air
are formed in the interior, which are discovered when the regulus is
broken. ‘These cavities often communicate with the surface. This
property of tellurium also belongs to selenium; it influences the den-
sity of the metal; Miiller of Reichenstein found it to be 6343, Klap-
roth 6115, and Magnus 6:1379. Berzelius found great difficulty in
determining the density ; the metal, which sublimed in drops in di-
stillation with hydrogen gas, had a density of 6°1305, which is less
than above stated, and proves that these drops also had cavities.
Several fragments taken from a regulus which had a cavity, and from
near it, gave the following numbers : 6°2324, 6:2516, 6:2445, 6°2578.
The meau is 6°2455, but it is proper to take the greatest as the true
density, since the cause of the discordant results tends to render them
too light.

ACTION OF OXACIDS ON PYROXYLIC SPIRIT—NITRATE OF
CARBOHYDROGEN.

[Continued from vol. vii. p 539. ]

Justice to Dr. Thomson induces me to copy the following from the
Records of Science :

«© Dumas has unnecessarily coined a new name to distinguish this
base, viz. Méthyléne (from pe@u, wine, and in, wood). What advan-
tage is gained by this innovation it is difficult even to guess at. The
disadvantages of designating simple compounds by arbitrary names
(since this compound turns out to be one of the simplest organic com-
pounds with which we are acquainted) are sufficiently obvious, and we
trust that this name will not be adopted by British chemists.

“« The existence of this simple compound of hydrogen and carbon
in pyroxylic spirit was demonstrated in 1326 by Dr. Thomson. (Edin.
Trans., xi. 15. Inorganic Chemistry, i. 194; ii. 294.) It is difficult
to allow ourselves to suspect that Dumas should have been ignorant
of this fact, which has been published for nine years; but, in conse-
quence of the absence of any allusion to it, it is impossible in charity
to avoid drawing such a conclusion.”

To the above I will only add that MM. Dumas and Peligot have
committed a most useless innovation in calling the nitric acid azotic

86 Intelligence and Miscellaneous Articles.

acid. This is the more remarkable, because M. Dumas, in the fifth
volume of his Chimie appliquée aux Arts, printed in 1835, employs
the term nitric acid and nitrate of méthyiéne.—R. P.

Nitrate of carbohydrogen is obtained with difficulty by the direct
action of nitric acid upon pyroxylic spirit. At first nothing remark-
able is obtained ; but towards the end of the operation red vapours
are procured, which are a mixture of nitrate of carbohydrogen and
formic acid,

It is, however, easily obtained by the following process. Put into
a retort 50 grammes of powdered nitre, and add to it as soon as made
a mixture of 100 grammes of sulphuric acid and 50 of pyroxylic spirit :
the retort should be large, the receiver tubulated, and it is to commu-
nicate with a bottle containing salt water, placed in a freezing mix-
ture, and with a tube to conduct the gases into a chimney.

The heat given out by the mixture and action of these substances
is sufficient to produce their mutual decomposition and the produc-
tion of the nitrate of carbohydrogen. A smal] quantity of red vapour
appears in the apparatus; while, on the contrary, much ethereal
matter is produced, which condenses partly in the tubulated receiver
and partly in the cooled bottle.

When the operation is over there is obtained at the bottom of the
bottle a thick and colourless stratum of the new ether. In order to
purify it, it must be decanted, several times distilled from a mixture
of massicot and chloride of calcium. ‘The distillation should be per-
formed in a bath of boiling water ; the quantity of the new compound
obtained is equal to that of the pyroxylic spirit employed.

This product is not, however, pure, and evidently contains several
different substances. When distilled, the boiling point is at first 140°;
it then gradually rises to 152°, and goes on without further altera-
tion. The portion distilled between 140° and 145°, exhales a very
distinct odour of bydrocyanic acid; it is probably formed of carbo-
hydrogen. The portion which boils at 152° is the most abundant, and
evidently the purest, The authors consider it, provisionally, as nitrate
of carbohydrogen; it is colourless, has a weak ethereal odour ; its
density 1-182 at 72°. It is perfectly neutral; it burns rapidly witha
yellow flame. When a few drops are put into a tube, and it is heated,
it is soon vaporized, and detonates with force if the heat be conti-
nued. It detonates with violence on the approach of flame; and a
receiver containing 15 cubic inches might occasion serious accidents
if exploded.

While it remains liquid it is not dangerous, but its vapour at a tem-
perature not exceeding about 300°, detonates with singular violence ;
in fact it contains azote, hydrogen, and carbon, elements analogous to
those of gunpowder: the products of the detonation are nitric oxide,
carbonic acid, and water.

By analysis it appears to be composed of

Carbon 45 ciiqewiaesidyy s) cet, FE,
Pydropens..Ssisnnecas a dae
AGT OSTA Janes ty eps! the 18:2
OXyBENs cc..egitw sins) el Dee

»

Intelligence and Miscellaneous Articles. 87

While nitrate of carbohydrogen would give by calculation :
C3 WSO fie 21s Behar

Hap eearear rs! .. 38
Aa 157-0. 3.2. SAS
OheeeGeo-d:..:, 2 62'1

967°5 100:

When it is heated with a solution of potash in alcohol, rapid de-
composition takes place, and crystals of nitrate of potash are formed
in considerable quantity, the formation of which cannot be explained
on the supposition of its being a nitrite instead of a nitrate of carbe-
hydrogen ; and a nitrite would yield results further removed from
those above given than those of a nitrate,

[To be continued. ]

SCIENTIFIC BOOKS.

New Scientific Journal.—On April Ist, 1836, will appear Tue
Lonvon Georoaicat Journat, No. I., with coloured engravings, by
J. de Carle Sowerby, F.L.S., of new Fossil Echinide from the English
strata.

Herpetologia Mexicana ; seu Descriptio Amphibiorum Nove Hi-
spaniz. Pars Prima, Saurorum Species amplectens. Adjecto Syste-
matis Saurorum Prodromo, additisque multis in hune Amphibiorum
ordinem observationibus. Edidit Dr. Arend Fr. Aug. Wiegmann,
Accedunt Tabule lithographicee decem.—Lately published at Berlin.

METEOROLOGICAL OBSERVATIONS FOR NOVEMBER 1835.
REMARKS.

Chiswick.—November 1. Hazy: clear. 2. Dense fog: rain, 3. Rain.
4, Overcast. 5.Cold: haze. 6. Sharp frost: fine: slight fog. 7. Frosty
haze: rain at night. 8. Clearand fine. 9—12, Cloudy and cold. 13. Rain:
fine. 14.Fine. 15. Cloudy. 16. Fine. 17. Hazy. 18. Overcast:
fine: clear at night, with extensive aurora borealis which illuminated
the whole of the visible northern hemisphere. At times the streamers ex-
tended from the horizon even beyond the zenith. 19. Very fine.
20. Slight haze. 21. Clear and fine. 22. Overcast: cloudy and windy.
93, Rain: fine. 24,25. Very fine. 26. Hazy: fine. 27, 28, Overcast :
rain: fine. 29. Rain. 30. Rain: fine. ©

Boston. —November 1. Fine. 2. Foggy. 3. Rain. 4—6. Cloudy.
7. Cloudy: raine.m. 8,9. Cloudy. 10. Cloudy: raina.M. 11. Fine.
12, Rain. 13, Cloudy. 14. Cloudy: rain p.m. 15—17. Cloudy.
Is—21.Fine. 22.Cloudy. 23.Rain, 24.Cloudy. 25. Cloudy: rain
pM. 26-28. Fine. 29. Cloudy: rain all night. 30. Cloudy: rain a.m.

[We have incorporated with our Meteorological Table on the next page,
a selection from the Observations made at the Apartments of the Royal
Society, Somerset House, London, by the Assistant Secretary, by order of
the President and Council, as published in the Atheneum ; and we shall
continue to do so in future, giving in our next the altitude and other par-
ticulars of the station.)

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LONDON ano EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]

FEBRUARY 1836.

XVI. On Capillary Attraction and the Molecular Forces of
Fluids. By the Rev. James CHAuts.*

i Laplace’s capillary theory the fluid is supposed to be

perfectly incompressible ; and the only forces acting on it
besides gravity, are assumed to proceed both from its own
molecules and those of the solid with which it is in contact,
to be wholly attractive, and to become insensible at all sensi-
ble distances from the attracting centres. Calculations made
on these hypotheses serve to explain phenomena in a remark-
able manner. But the principles of this theory are liable to
objection, as no account is taken of a repulsive molecular ac-
tion, whilst, on the supposition of a molecular constitution of
the fluid, the particles could not be held in places of equili-
brium but by the action of repulsive as well as attractive
forces. ‘The theory of M. Poisson not only meets this ob-
jection by regarding the fluid as composed of insulated mo~
lecules subject to the opposite tendencies of attractive and
repulsive forces, and as liabie to compression, but takes into
consideration also the effect of the variation of density, which,
according to this constitution of the fluid, must exist within
a small depth both from its free surface and from that in
contact with the solid. This, no doubt, is the only complete
method of treating the problem. The next inquiry is, to
what degree is that superficial variation of density effective?
M. Poisson’s theory does not bear on this point, and experi-

* Communicated by the Author.

Third Series. Vol. 8. No. 45. Feb. 1836. N

90 The Rev. J. Challis on Capillary Attraction

ments have not succeeded in establishing even the existence
of such a variation.

The object of the following remarks is to show, in the first
place, that capillary phenomena will be little affected by the
superficial variation of density, when the molecular attraction
is feeble compared to the repulsion, and the sphere of attrac-
tive activity great compared to that of the repulsive activity ;
and then to give a reason for supposing the molecular forces
of fluids to be of this nature, by showing that such an hypo-
thesis will account for their fluzdity.

The constitution of fluids is here assumed to be molecular,
and the molecules are conceived to be held in places of equi-
librium by attractive and repulsive forces, which near the
boundaries of the fluids necessarily produce a variation of com-
pression. The condition of equilibrium of the molecules at
the free surface requires the extent of action of the attractive
force to be greater than that of the repulsive, while experience
shows that the sphere of molecular activity is of insensible
magnitude. With respect to any point at a sensible distance
from the surface, if we conceive a plane to pass through it,
the resultant of the repulsions it is subject to from the action
of the particles on one side of the plane will be perpendicular
to the plane, and equal and opposite to the resultant from the
action of the particles on the other side. The same may be
said of the attractions. But the attractive resultant may be
very different from the repulsive resultant. The ratio of the
two may be taken as the measure of the proportion of the
attractive to the repulsive action of the fluid. Let us now
assume the attractive action to be very feeble compared to the
repulsive, but to have a much larger sphere of activity, and
consider what will result from this hypothesis.

Conceive m an to represent the projection of the plane
surface of the fluid on the plane of the paper; abcd, a
normal to the surface; a b, the radius of the sphere of re-
pulsive activity, and } d the same for the attractive force.

Let the spherical surface afc e be described with centre
6 and radius 6 a; and m d n, a portion of a spherical surface,
with centre 6 and radius bd. The former surface includes
all the atoms which exert a sensible repulsive force on an atom
at b, and the space between this surface and the latter in-
cludes all the atoms whose attractions are sensible at the

same point. The resultants both of the attractive and re-
pulsive forces on 6 will be in the normal acd. The attrac-
tive resultant is the excess of the action of hdkecf above
that of mafh and »aek, and takes effect in the direction
bc. The repulsive resultant is the excess of the action of the

and the Molecular Forces of Fluids. 91
hemisphere fc e above that of the hemisphere fae, and is

ad

effective in the direction b a. “These two resultants must be
equal. But as a é is small compared to 6 d, the attraction
on 6 will differ little from the attraction on a. And as the
latter must be just equal to the repulsion of the hemisphere
ps, whose radius = a 6, it follows that this repulsion is
very little greater than the difference of the repulsions of fc e
and fae. That this may be the case, there must be a rapid
variation of density at a, and at the same time, on account
of the feebleness of the attractive resultant, a small variation
at d. The repulsion on any particle will thus be chiefly
owing to the action of the particles in its immediate neigh-
bourhood, and be increased but little by the action of the
more remote particles within the sphere of activity. The law
of repulsion will be one of rapid diminution with the increase
of distance from the repelling molecule; and the depth to
which the superficial variation of density is considerable, will
be less than the radius of the sphere of activity of the repul-
sive force, and therefore much less than that for the attractive
force. And if the variation of density is inconsiderable at 4,
d fortiori it will be so at all points intermediate to 5 and d.

When, therefore, it is required to investigate any effect due
to the molecular attractions of fluids, the superficial variation
of density may be neglected, if the suppositions on which the
foregoing reasoning is founded be correct; and by treating
the fluid as incompressible, the repulsive force will be taken
account of with the same kind of approximation as when, in
problems on the common theory of fluids, a change of pres-
sure is supposed to be unaccompanied by a change of density.
According to these views Laplace’s hypotheses suffice for a
theory of capillary attraction, and any theory which, like that
of M. Poisson, leaves the laws of the attractive and repulsive
forces perfectly arbitrary, would seem to be not inconsistent
with Laplace’s, but inclusive of it.

N2

92 The Rev. J. Challis on Capillary Attraction

The way in which the above hypothesis may be conceived
to account for the fluidity of fluids may be stated as follows:
The distinguishing characteristic of fluids is the facility with
which the relative positions of different parts may be made to
change, excepting when the forces applied tend to compress
the whole mass into a smaller space. Now, since it is a con-
sequence of our hypothesis, that the repulsive force of each
atom varies very rapidly with the distance, and the attractive
force slowly, the above-mentioned property will be accounted
for by saying, that any cause which compresses in a very slight
degree any portion of the atoms, by diminishing their mutual
distances, calls into play their repulsive action, without sen-
sibly affecting their attractions on each other, or on particles
more remote, so that they will be ready to obey any inequality
of repulsion without drawing surrounding particles with them.
Suppose, for instance, a plate of small but finite thickness
were dipped in a fluid with its planes vertical. When it just
begins to enter, it compresses the particles immediately under,
and by diminishing their mutual distances calls forth a repul-
sion, which again compresses and puts in motion the conti-
guous particles: these in like manner act on the next in suc-
cession, and so on till the whole mass is made to yield to the
immersion. If at the same time a sensible attractive force
were excited by the compression, the surrounding particles
would be drawn towards the compressed parts, and the effect
on those at the surface would be a depression near the im-
merging plate, such as we know to take place when a solid is
dipped in a semz-fluid substance. An obstacle would thus be
presented to the immersion of the plate, the same in kind as that
presented by a solid, the rigidity of which, according to this
theory, will be owing to a great degree of energy in the mo-
lecular attractions. But when the attractive forces are very
feeble, there will be little resistance to the immersion besides
that arising from the inertia of the particles, and the fluidity
will consequently be nearly perfect. This distinctive pro-
perty which fluids possess of being readily divided, I have
elsewhere observed, may be conveniently employed as a prin-
ciple from which the fundamental equations relating to their
equilibrium or motion may be derived.

Some mathematical consequences, which, as I am about to
show, follow from the views expounded above, will also serve
to confirm the initial hypothesis. Admitting that the varia-
tion of density at the surfaces of fluids has small influence on
any effects resulting from their molecular attractions, and that
the molecular repulsions are taken account of by supposing

and the Molecular Forces of Fluids. 93

the fluid incompressible, we may employ the common equa-
tion of the equilibrium of fluids, viz. dp = e@(Xd2+Ydy
+Z ds), in questions relating to capillarity. 1t is well known
that this equation determines the resultant of the forces acting
on any particle at the surface to be perpendicular to the sur-
face.

Let ANQ be the projection on the plane of the paper of
a fluid surface near its contact with a plane solid surface,
supposed to be projected into the straight and vertical line
AB. Drawa tangent AT at A. The resultant of the forces
acting on a particle at A will be
perpendicular to AT. Conceive a
plane perpendicular to the plane of
the paper to pass through A, and
to make an angle 6 with AB; and
another plane, similarly situated, to
make an angle +89 with the same
line. Then 20 being indefinitely
small, the attraction of the fluid
between the planes on A will vary
as0$. Let it = qg24, and let the
angle TAB = ¢. The total at-
traction of the fluid between the
planes A T and AB on A, will in
the vertical direction be fg d 4 cos 4
[from 6 = 0 to 6 = ¢], or g sing; and in the horizontal di-
rection, fgd 4 sin 6 [from 6 = 0 to § = ¢], or g (l— cos¢).
The resultant of the solid’s attraction, which will be in the
horizontal direction, will be found by putting gq! for g, and
180° for ¢ in the last expression, and will consequently be
2q'. The resultant of the attraction of the portion Q AT
between the surface and the tangent plane will be nearly in
the direction AT. Calling it £, and the force of gravity g,
the whole attraction in AB =g+q sing+é cos ¢, and
that in the horizontal direction = 2 q'—g (1—cos¢) —k sing.
Since the resultant of these is perpendicular to A T, their
ratio = tan ¢, from which equality we readily obtain

(2q'~— 9) sing = gceoso+h.

Now, for all fluids capable of hanging in drops of sensible
thickness from the horizontal surface of the solid, 2¢q' is
greater than q; and considering the small extent of activity of
the molecular forces, both g' and g must be exceedingly
greater than gravity. Also if ¢ be an angle of considerable
magnitude, “ must be much smaller than the left side of the

94 The Rev. J. Challis on Capillary Attraction

equation. Hence this equation cannot in general be satisfied
except for a very small value of ¢. If the surface were hori-
zontal, we should have * = 0, cos¢ = 0, and therefore
2q' = q. This relation appears to be nearly satisfied be-
tween mercury and glass, since the experiment of Casbois
shows, that by merely boiling the mercury, its upper surface
in a capillary glass tube may become horizontal, or even con-
cave. The reasoning by which ¢ was shown to be in general
a very small angle, does not apply to mercury, which is inca-
pable, like water and oils, of adhering to a solid. The small-
ness of the angle of actual contact, seems to be a condition
always satisfied, whenever a fluid moistens a solid*.

It is not possible to determine theoretically the form of the
curve A N Q near the solid, because the laws of the mole-
cular forces are unknown. Considering, however, the small
extent of their sphere of activity, we may say that for a small
distance the curve will be the same, whether the fluid rise
against a plane surface or in a capillary tube. Let N bea
point of the fluid surface situated just beyond the sphere of
sensible action of the solid, let N R be drawn vertically, and
the angle QN R =. It is proved, on the supposition of
incompressibility, (see Poisson’s New Theory of Capillary
Action, art. 18,) that the quantity of fluid raised in a given
tube varies as cos w. Now, as it is shown above that the an-
gle ¢ of actual contact is constant, and very small, it follows
that the angle w, and consequently the heights of ‘ascent, may
be different for different relative positions of A and N. If
the fluid ascend ina tube not previously wetted, the points A
and N will be nearest each other, » will have its greatest value,
and the height of ascent be least. As A and N are more re-
moved from each other by wetting more of the solid surface,
the rise of the fluid may be expected to be greater, and to
attain its maximum value when the moistening is carried to
such a degree, that the solid can retain no more fluid attached
to it. In this case the influence of the solid on the form of

* The views which this communication is intended to explain are stated,
in part, at the close of my Report on Capillary Attraction (contained in
the Fourth Report of the British Association), to which I take this oppor-
tunity of referring for the sake of pointing out an error in the remarks
(p. 273.) on an equation of Laplace’s theory, equivalent to that obtained
above, excepting that gravity is not taken into account. It is not true,
as there stated, that Laplace neglects the superficial variation of pressure.
The strictures of Dr. Young upon it, adduced at p. 266 of the Report,
will appear to be inapplicable from the reasoning above, which it is hoped
will serve to place the inferences to be drawn from this equation, and its
importance in the capillary theory, in a true point of view.

and the Molecular Forces of Fluids. 95

the fluid surface will be the least possible, and the column
may be considered to be supported by the action of the fluid
on itself. The fluid will thus hold the place of the solid in
the equation previously obtained; we shall have q' = 4, and
the equation will become

gsing = gcos¢ +k.

Hence, on account of the smallness of g and & compared to
g, the angle of contact with the aqueous tube will be small as
well as of that with the solid. Consequently the intermediate
angle » will be small, and the heights of ascent be the same
whatever be the solid, if the fluid thoroughly wets it. In the
experiments of M. Link, (see Poggendorfi’s Annalen 1833,
p. 404,) the condition here supposed was fulfilled by means
of an apparatus for dipping the solid repeatedly in the fluid.
The height of ascent is found to be independent of the nature
of the solid, or nearly so. In subsequent experiments, (Pog-
gendorff’s Annalen, 1834, p. 5935) the plates between which
the fluids ascended were previously dipped in strong caustic
alkali and concentrated sulphuric acid, to get rid of a film of
grease attaching to them, which they contract in the act of
polishing. Water, in these new experiments, stood very
nearly at the same height between glass, copper, and zinc
plates. Other fluids did not follow this law, and in the in-
stance of sulphuric acid, the deviation appeared to depend on
a chemical action between the solid and fluid. Such a cir-
cumstance would be likely to affect the form of the curve
ANQ and angle », and consequently, according to the
theory, the height of ascent.

The general inference from the foregoing reasoning is, that
the heights of ascent do not merely depend on the molecular
attractions, but, while these remain the same, may be affected
by any circumstance that alters the form of the fluid surface
near the solid, and particularly by the manner and degree of
moistening the solid by the fluid. In this way the differences
of the heights, as determined by different experimenters, may
be accounted for.

The maximum height of ascent in a given tube varies, ac-
cording to theory, for different fluids, as a certain quantity

—, in which ¢ is the specific gravity of the fluid, and H* de-
g
* This is the quantity called H by Poisson, and by Laplace in his Sup-
plementary Treatise. The quantity so denominated in Laplace’s first
Treatise is equal to —. This letter is inadvertently used sometimes in

one of these senses, and sometimes in the other, in the Report on Capil-
lary Attraction,

96 The Rev. J. Challis on the Molecular Forces of Fluids.

pends on the law, intensity, and sphere of activity of its mo-
lecular forces. Admitting the superficial variation of density
to be negligible, and the fluids to be incompressible, H_ will
be a measure of their cohesiveness, or the inverse of it a mea-
sure of their fluidity, as it is proportional to the effect of their
molecular attractions acting under the same circumstances.
(Laplace’s Treatise, art. 12. and Supplement, p. 18.) On
this account it formerly appeared to me simplest to suppose
this quantity to vary ase; and the first experiments of
M. Link favoured this idea by assigning to different fluids
the same height of ascent. Those subsequently made, which
are the more accurate, do not give the same result, but suffi-
ciently prove that the heights are not as the specific gravities,
and consequently that H does not vary as 9°, as is usually
supposed. Probably nothing can be determined respecting
it d priori. The last-mentioned experiments gave the fol-
lowing results when the fluids ascended between glass plates
thoroughly moistened:—height x specific gravity = 5:3, for
sulphuric ether; 6°7, for alcohol; 10°7, for liquid caustic
alkali; 10°9, for liquid ascetic [carbonated ?] alkali; 12:5, for
water; 15°6, for muriatic acid; 16°8, for nitric acid; 20°3,
for sulphuric acid. According to what is said above, these
numerical quantities are in the order of cohesiveness, sul-
phuric ether being the least cohesive body, or possessing the
greatest degree of fluidity.

The phenomenon of endosmose may be appealed to as in-
dicating a great attractive energy in partially fluid substances.
When water is on one side of the porous membrane, and an
imperfect fluid, as treacle, or solution of gum, on the other,
the latter is found to draw the water powerfully through the
pores. The force exerted at any time appears by experiment
to be in this case proportional to the difference of the den-
sities of the fluids on the opposite sides of the membrane.

The subjects treated of in this paper are of such a nature
as scarcely to admit of any very definite discussion. Since,
however, the degree in which capillary phenomena may be
affected by a variation of density at the surfaces of fluids is at
present quite unknown, it seemed desirable at least to ascer-
tain whether an approximation to the truth is obtained when
that variation is neglected; and, perhaps, the preceding rea-
sons, connected with the nature of fluidity, may make it pro-
bable that such is the case.

Papworth St. Everard, Dec. 10, 1835,

Bote]

XVII. Letter from Peter Barlow, Esg., F.R.S., to the Rev.
D. Lardner, LL.D., F.R.S., on the Theory of Gradients in
Railways.

Dear Sir,
AS you have addressed a letter to me in the last London

and Edinburgh Philosophical Magazine, I feel myself
bound by courtesy to reply to it through the same Journal,
not, however, with a view of entering into any controversy on
the question. You have in your letter very clearly stated your
mode of solution, I will endeavour to explain also the grounds
of my objection; the readers of the Lond. and Edinb. Philo-
sophical Magazine will then be able to form their own judge-
ment.

First, ¢ being the fraction expressing the ratio of the fric-
tion to the load, and ¢ the angle of the plane’s inclination, you
take ¢ to denote the resistance on the horizontal plane, ¢
+ sine to denote the same on the ascending plane, and
¢ — sin e for the same on the descending plane. ‘Then, assum-
ing what may not, perhaps, be quite true, (but to which I do
not here make any objection,) 2. e. that in locomotive engines
the power generated and expended is the same in the same time,
you arrive at the conclusion, that in cases of uniform velocity
the resistance into the velocity is constant: taking, therefore,
V to denote the velocity on the horizontal plane, and v the ve-
locity on the descending plane (which you also assume to be
uniform), you arrive at the equation

(¢— sine) v = 7V.
wv iV

iy #Semies
And by this formula your tables of velocities are computed for
the Great Western and Basing lines; but where the formula
gives more than 40 miles an hour the results of the computa~

tion are not stated.
Thus, for example, assuming, as you do, 25 miles to be the

Whence

, , 1
velocity on a horizontal plane, and ¢ = 250° the formula be-
comes

_ ‘I
(:004—sin e)"

I have gone over all the numbers in yqur four tables, and,
except very trifling numerical errors, I find your results con-
sistent with this formula as far as you have given the com-
puted velocities; but those which you have not stated (by

v=

98 Letter from Peter Barlow, Esq., to Dr. Lardner,

supposing the break to be employed) are so extraordinary
that I think you can scarcely consider them as correct.
For example, taking a very common gradient of 16 feet to

a mile, or sine = nina ea find
|

_ (004 —355
Such a gradient is very common in practice, and in practice
in such a case the break is not applied. The computed and
practical result ought, therefore, to agree, supposing the
solution correct ; but such a velocity as one of 103 miles per
hour has never yet, I believe, been obtained.

Again, with a slope of 1 in 250, by no means an uncom-
mon gradient, your formula gives the velocity of descent zn-

finite: now such gradients are descended without the break,
but, of course, not with an infinite velocity. For slopes
greater than the last, of which also there are many, your ve-
locity passes through infinity, and becomes negative, and the
time of descent negative also, or less than no time.

I have certainly stated in my Second Report to the Direc-
tors of the London and Birmingham Railway Company, that
a solution which leads to such extraordinary results must be
‘erroneous both in theory and practice.” And my opinion is
not altered. The error, I conceive, arises from combining the
two dissimilar forces ¢ and sin <, and then treating the ques-
tion of descent as one belonging to the case of uniform mo-
tions; whereas (according to my view of the subject) it pro-
perly belongs to the class of accelerated motions.

Your solution, however, and my objection to it are thus
placed before the readers of the London and Edinburgh Phi-
losophical Magazine, and I leave the question in their hands.

I remain, dear Sir, yours truly,
Woolwich, Jan. 2, 1836. PETER Bartow.

v Ti 103:09 miles per hour.

After closing my letter, I have thought it might be satis-
factory to some of the readers of the Phil. Mag. to see the
view I take of this question, which is as follows.

Suppose a body free from friction to arrive at, or to be pro-
pelled from, the upper end of an inclined plane with a velo-
city v, and let the angle of the plane = «, then the velocity
acquired by that body in the time ¢ will be v + 2g. sine. ¢;
and the space descended will be ¢v + g sin ¢.2°; (g denoting
the space fallen through by gravity in one second, or g
= 16,, feet.)

Suppose now a body subject to friction to reach the same
plane with the same velocity, but that this body. contains

on the Theory of Gradients in Railways. 99

within itself an acting power which exactly balances the fric-
tion at all velocities; then I consider that the descent of this
body wiil take place under precisely the same circumstances
as the former, and therefore that the space described in the
time ¢ will be as before27 = ¢v + g sin <.é, and that in both
these cases the velocity will be uniformly accelerated.

But if the internal acting power within the body will only
balance the friction when the velocity of the body is v, there
will be three circumstances on which the velocity of descent
will depend, viz.

First, the original velocity = v.

Secondly, the accelerating force = g sin «.

Thirdly, the retarding force arising out of the excess of
friction beyond that of the internal force employed to over-
come it.

In this form the solution of the problem falls under the
case of variable forces, and is so involved as not to admit of
solution without employing differentials of the second order.

Now, I consider a locomotive engine to be a body constituted
as above supposed, that is, liable to friction, but containing
within itself an acting power capable of overcoming the fric-
tion, so that where gravity does not act, the motion of the
body continues uniform; and if on reaching a descending
plane, the internal force was still such as to balance the fric-
tion due to the increased velocity, then its descent would be
governed by the same laws as supposed in the second case, that
is, the velocity after any time ¢ would bev’ = v + 2tg sin ¢,
and the space described would be 7 = tv + g sine.@.

The actual law of locomotive machines is not yet well un-
derstood ; some engineers are of opinion that an increased ve-
locity, by throwing the steam faster into the funnel, causes an
increased draught, which produces a proportionally greater
quantity of steam, in which case the above would be an ex-
act expression for the space described; and if it is not so, and
we still reject the consideration of retardation, then at all
events the above formula will mark a limit in the problem,
and the velocity and space thus obtained will be the greatest
that can be acquired in a given time. This, therefore, is the
most favourable view of the question for Dr. Lardner in com-
paring his velocities with mine. Let us see, then, what the re-
sults are on this supposition. We have seen that, 7 being any
length of plane, gsine® + vi = 1,

1 Sale si ae

or Ps

: vt = =! sans
g sine gsine gsin’e¢
h denoting the height of the plane.

100 Letter from Peter Barlow, Esq., to Dr. Lardner.

By the solution of this equation, we obtain

pos 1 = 2

( and v being taken in the same measure,) and the last ac-
quired velocity v' will be
v= f/(v+4gh).

Taking now the first example given in my letter, that is to
say, a plane sloping 16 feet in a mile, and let the length of
the plane be half a mile, (which is one of the cases in the
Basing line given by Dr. Lardner in his table): Here, since
v = 25 miles, and h = 8 feet: we find v’ = 29:29 miles per
hour for the greatest velocity, and 27:11 miles per hour for
the mean velocity; whereas, Dr. Lardner’s formula gives the
uniform velocity of descent 103:09 miles per hour.

The time of descent will, in like manner, by my 1™ ¢
formula be Seeceeseeces ess eeseese esessteseeeseesees 6
By Dr. Lardner’s formula.......scsscssesseeseseers 0 17

Taking the second example, of a slope of 1 in 250, and the
length of plane half a mile, we have
h = 103 feet nearly.
Whence v, the greatest velocity ... ... +. = 303 miles.

Mean velocity = 271

Time of descenté = 1™ 5%.
By Dr. Lardner’s formula the velocity = infinity.

Time of descent = zero.

With these very wide differences in our results, it must be
that one of the two solutions is wrong, and without saying
which, I am, on my part, quite content to leave the decision
to those whose minds have not already received a bias from
preconceived notions of the forces. A locomotive power is
rather a novel consideration in mechanics; and either Dr.
Lardner or I have certainly taken a wrong view of the subject,
that is, of the * fundamental law of gravitations.” ‘That the
results as computed by Dr. Lardner’s formula are inconsistent
with practice there can be no doubt, and how that can be theo-
retically right which is practically wrong is rather difficult to
conceive.

eam Ts

XVIII. On Symbolic Notation, as applied to Mineralogy. By
H. J. Brooxs, Esq., F.R.S. F.L.S. £.G.S.

To Richard Phillips, Esq.
Dear Sir,

HAVE, at the repeated solicitation of several of my friends,

undertaken and made some progress in a new work on
Mineralogy, in the course of which some difficulties have oc-
curred relative to the chemical constitution of minerals and
their distribution into species, which perhaps some of your
chemical readers may assist in removing; and on this account
I shall feel obliged by an early insertion of this notice in your
Journal.

Before I commenced the work in which I am engaged, I
had thought of proposing a new edition of the late W. Phil-
lips’s useful volume; but upon a close examination of its con-
tents I found it would require so much correction, and so great
a remodelling, to adapt it to the present state of mineralogical
knowledge, that it would be less troublesome to prepare a new
treatise.

Notwithstanding the decided objection entertained by you
to the use of symbols, I am disposed to regard them as very
serviceable in ceconomizing time and labour ; and it will pro-
bably turn out that your objection applies rather to the unne-
cessary and capricious changes to which these short-hand
characters have been subjected, and their employment in the
expression of conflicting theories, than to the characters them-
selves.

Symbols were first introduced by Berzelius, which fully
answered the purpose for which they were intended; and it
would have been much better, and much confusion would have
been spared, if they had been rigidly adhered to, notwith-
standing any slight improvement of which they might have
been susceptible. But, unfortunately, in the symbolical repre-
sentations of the composition of minerals published by dif-
ferent authors, not only are the symbols of Berzelius changed,
but the formule are made up according to the peculiar views
of each author concerning atomic weights, and their several
notions of the most fit manner of parcelling out into definite
compounds such of those constituents of a mineral, as given
by analysis, as they choose to consider essential to its constitu-
tion, after having rejected whatever they imagine to be foreign
matter.

These differences will be apparent on a comparison of the
analyses of different minerals, as given by Leonhard in his
Handbuch der Oryctognosie, and by Thomson in his recently

102 On Symbolic Notation, as applied to Mineralogy.

published work on Mineralogy, with the formule by which
the composition of such minerals is expressed.

Hence arises the difficulty in selecting a chemical formula
which shall accurately represent the chemical constitution of
a mineral, and particularly as other symbolical expressions
might, with a little contrivance, be framed to represent equally
well the result of the same analysis. A question, therefore,
occurs whether there is any rule to guide us in determining
which formula is the most correct.

The doctrine of definite proportions is, as I understand it,
applicable to all cases of chemical union. An electro-positive
and an electro-negative element are, in all cases, to be regarded
as the combining atoms, whether such elements are simple, or
consist of binary, quaternary, or any other compound of simple
elements. Thus, one proportional of oxalic acid and one of
potash are the combining atoms in oxalate of potash ; in binox-
alate, two proportionals of the acid form the atom; and in qua-
droxalate four proportionals. But in what manner do these
two and four proportionals constitute the combining atoms?
Again, in sulphate of nickel and potash, are the two elements
sulphates; or is sulphuric acid one, and the combined oxides the
other? And what function does the water perform in hydrous
salts, as it does not appear in the formule representing such ?
in what manner, or even whether it is combined with any, or
which, of the elements of the compound in which it occurs ?

On referring, however, to the last edition of Berzelius’s
Theory of Chemical Proportions, I find that the inquiry I
have thus ventured to suggest will probably not produce a sa-
tisfactory answer; but as some chemists retain in their formule,
and others reject, the same ingredient of a mineral, as shown
by analysis, they perhaps have some rule by which they are
guided, and which if worked out might furnish a clue to the
object Iam seeking. The passage from Berzelius is as follows:
¢ Sulphuric acid, potash, alumina, and water are compound
atoms of the first order; sulphate of potash and sulphate of
alumina are of the second order ; dry [anhydrous] alum, of the
third order; and lastly, crystallized alum, containing water com-
bined with the double sulphate, may be regarded as an atom of
the fourth order. We are as yet ignorant of the extent of the
number of these orders. Affinity among compound atoms de-
creases rapidly as the numbers of the orders increase; and the
degree which exists even among atoms of the ¢hird order is too
feeble to be observed in the operations of the laboratory. This
affinity is seldom manifested, except in minerals; and to un-
derstand thoroughly the nature of these, it is necessary to know
how far the combination of compound atoms can take place,

On Reflexion from Crystallized Surfaces. 103

and whether there is any limit to the numbers of the orders of
the combining atoms.”

Under these circumstances, it would have been better not
to construct any mineralogical formule, except the simple
ones; and in future the composition of such minerals as
involve the uncertain orders of atoms should be expressed
simply by the proportion of each ingredient in 1000th parts,
or by the nearest equivalent numbers of each, taking the
element which occurs in the smallest quantity as an atomic
unit. We should then express by our formule what we know,
instead of contriving to represent an imaginary atomic consti-
tution, which, if the atomic theory be true, is probably in all
cases false.

I am, dear Sir, yours truly,
January 7th, 1836. H. J. Brooke.

XIX. On the Laws of Reflexion from crystallized Surfaces.
By J. MacCuraen, Fellow of Trinity College, Dublin.

To Sir David Brewster.
Dear Sir,

I HAVE great pleasure in sending you an account of the

laws by which I conceive that the vibrations of light are
regulated when a ray is reflected and refracted at the sepa-
rating surface of two media; especially as the only guide
which I had, in my inquiry after these laws, was your paper
on the action of crystallized surfaces upon light, published in
the Philosophical Transactions for the year 1819.} The observa-
tion which I found there, that the polarizing angle was the
same for a given plane of incidence, ‘‘ whether the obtuse
angle of the rhomb [of Iceland spar] was nearest or furthest
from the eye, or whether it was to the right or left hand of
the observer,” disappointed me at first, being contrary to
what I had anticipated from principles analogous to those
which had been employed by Fresnel in the problem of re-
flexion from ordinary media. I then sought other principles,
and the observation is now a result of theory.

Assuming, as a basis for calculation, that Fresnel’s law of
double refraction is rigorously true, I have been obliged to
make an essential change in his physical ideas, Conceive an
ellipsoid whose semiaxes are parallel to the three principal di-
rections of the crystal, and equal respectively to its three
principal indices of refraction, and let a central section of the
ellipsoid be made by a plane parallel to the plane of a wave
passing through the crystal. The section will be an ellipse,
and the wave will be polarized by the crystal in a plane pa-

104 Mr. MacCullagh on the Laws of Reflexion

rallel to either semiaxis of this ellipse, the index of refraction
for the wave being equal to the other semiaxis. ‘This is
Fresnel’s law of double refraction; and the theory which led
him to it makes it necessary to admit that the vibrations of
the wave are perpendicular to its plane of polarization;
whereas, according to the views which I have adopted, the
vibrations of the wave are parallel to its plane of polarization,
and to one semiaxis of the elliptic section, while its index of
refraction is equal to the other semiaxis. ‘These views nearly
agree with the theory of M. Cauchy, according to whom
the vibrations of polarized light are parallel to its plane of
polarization, but inclined at small angles to the plane of the
wave in crystallized media, instead of being exactly parallel
to the latter plane, as I have supposed them to be. Besides,
the theory of M. Cauchy, founded on the six equations of
pressure in a crystallized medium, implies the existence of a
third ray of feeble intensity, ‘and for the other two rays gives
a law somewhat different:from that of Fresnel. Being obliged,
in order to account for your experiments, to abandon the
physical ideas of Fresnel, and to approximate towards those
of M. Cauchy, I was embarrassed by this third ray; and wish-
ing to get rid of it, as well as of the slight deviations from
the symmetrical law of Fresnel, 1 adopted the expedient of
altering the equations of pressure, in such a way as to make
them afford only two rays, and give a law of refraction exactly
the same as Fresnel’s. The equations which I found to an-
swer this purpose are the following:

belt Ze Me ee
Bre 0 ned aes
GE e(esi se st) Vg
Di ar i +a) ve
Se 524 5*) V9

F = c* ( A SLR

In these equations, the axes of coordinates are perpendicu-
lar to each other, and parallel to the three principal directions

Jrom crystallized Surfaces. | 105

of the crystal; x,y,z are the coordinates of a vibrating mo-
lecule at the time ¢; &, 7, %. are the components of the dis-
placement of the same molecule at the same time; a,b,c are
the three principal indices of refraction out of the crystal into an
ordinary medium in which the velocity of light is equal to V ;
and g is the density of the ether, which density I suppose to be
the same inall media. ‘The quantities A, F, E are the compo-
nents, parallel to the axes of x, y, 2 respectively, of the pres-
sure upon a plane perpendicular to the axis of x; F, B, D
are the components of the pressure upon a plane perpendi-
cular to the axis of y; and E, D, C, the components of the
pressure upon a plane perpendicular to the axis of z. The
values of D, E, F are the sameas those given by M. Cauchy;
but the values of A, B, C are different from his, and much
simpler. By introducing into the equations of M. Cauchy
the condition that the vibrations shall be performed without
any change of density, the resulting values of A, B, C might
be shown to agree nearly with those given above. The six
pressures, A, B, C, D, E, F, being known, it is easy to find
the pressure upon a plane making any given angles with the
axes of coordinates.

These things being premised, it is time to mention the laws,
or rather hypotheses, which’ I have imagined for discovering
the relations that exist, as to direction and magnitude, among
the vibrations in each ray, when reflexion and refraction take
place at the separating surface of two media, whether crystal-
lized or not. In stating the two very simple laws that have
occurred to me for this purpose, it will be convenient, when
the first medium is an ordinary one, to suppose that the inci-
dent light is polarized. Then by the first law, the vibrations
in one medium are equivalent to those in the other; that is to
say, if the incident and reflected vibrations be compounded,
like forces acting at a point, their resultant will be the same,
both in length and direction, as the resultant of the refracted
vibrations similarly compounded. By the second law, the la-
terval pressure upon the separating surface is the same in both
media; the lateral pressure being understood to mean the pres-
sure in a direction perpendicular to the plane of incidence.

As it would engage us too long to follow these laws into
detail, I shall merely state some of the results which I have
obtained from them, for the case of a uniaxal crystal into
which the light passes out of an ordinary medium.

Imagine the surface of the crystal to be horizontal, and call
the point of incidence I. With the centre I and any radius,
conceive asphere to be described, cutting in the point Z a
vertical line I Z drawn through the centre, and let a radius

Third Series. Vol. 8. No, 45. Feb. 1836. O

106 Mr. MacCullagh on the Laws of Reflexion

IP, parallel to the axis of the crystal, meet the surface of the
sphere in P. Let the great circle ZO E be
the plane of incidence, containing both the
direction IO of the ordinary refracted ray re)
produced backwards, and the direction I E ~ P
of a normal to the extraordinary wave; and R
draw the great circles PZ, PO, PE. The
angle Z will be the azimuth of the plane of incidence. Let
ZO=4,ZE=9,PO0O=y),PE=¥Y, the angle ZOP
= @, and the angle ZEP= 4. Call the angle of inci-
dence i, and suppose 6 to be the reciprocal of the ordinary
refractive index, and a the reciprocal of the extraordinary.
Each of the refracted rays, in turn, may be made to dis-
appear, by polarizing the incident ray in a certain direction
assigned by theory. When the extraordinary ray disappears,
the reflected ray is polarized in a plane inclined to the plane
of incidence at an angle 6 determined by the formula
a : igfit HV Bea sin? z :
| tan 6 = cos (i+ ¢) tan§+2 (a®—2*) sin 4 sin cos) ay ers G3)"
When the ordinary ray disappears, the plane of polariza-
tion of the reflected ray is inclined to the plane of incidence
at an angle 6’ determined by the formula

!
—tan f! = cos (7+ 4") cotan 6’ + (a*—6*) =a
ait es Se
sin Y cos V Sin (ia) (3.)

And when the angles B, 8’, become equal, the plane of po-
larization of the reflected ray becomes independent of the
plane of polarization of the incident ray; and the angle of in-
cidence 7, at which this equality takes place, is the polarizing
angle of the crystal. Hence we have the equation of condi-
tion

; Cae ey __sin®z
cos (i+ ¢) tan§+2 (a°—O*) sin§ sin cos ah
2 if & = 0.(4.)
aa a 1 ¢p27ey08 24. 1, , sin’ 2
+cos (¢+ 9 )cotan# + (a*—D*) ee a sin J’ cos singel)

to be fulfilled at the polarizing angle.
Since 7+, in this equation, is nearly equal to a right an-

gle, putz+$ = > + 8, and will be a small quantity. Draw

P R an arc of a great circle perpendicular to ZO E, and let

from crystallized Surfaces. 107

ZR=p,PR=gq. Then we shall find from equation (4.),
after various substitutions and reductions,

272
& = K cos* g (cos* $—cos*p); where K = (2 3 eres (5)

In deducing this value of 8, the approximations were made
with a tacit reference to the case of reflexion in air from a
common rhomb of Iceland spar. The coefficient K, in this
case, is equal to about nine degrees, and the resulting nume-
rical values of the polarizing angles in various azimuths agree
very well with your experiments. You will perceive that the
value of 3 is the same in supplementary azimuths, which ex-
plains the observation, cited in the beginning of my letter, re-
lative to the equality of the polarizing angles at opposite sides
of the perpendicular I Z in a given plane of incidence.

When the point R falls upon O, we have 8 = 0, and7+4
equal to a right angle. Hence, when the cotangent of ZR
is equal to the ordinary index, the tangent of the polarizing
angle is equal to the same index. This theorem, though de-
duced from an approximate equation, might be shown to be
exact.

When the axis of the crystal lies in the plane of incidence,
we may obtain an exact expression for the polarizing angle.
The condition of polarization then becomes

a af 2__},2) cin dl 1 APR Bs) jl

cos (2+ ¢')—(a°—0*) sin p' cos h ayia Age

from which, by the proper substitutions, we obtain the fol-
lowing expression :

0; (6.)

- 9. 1—a® cos? A—B? sin? A

sin? z.= a BP : (7.)
where A denotes the complement of Z P, or the inclination of
the axis to the face of the crystal, and z is the polarizing angle.
This formula, in a shape somewhat different, was communi-
cated, above a year ago, to Professor Lloyd, who has noticed
it, in connexion with your paper, in his Report on Physical
Optics. When a and become equal, the formula gives your
law of the tangent for ordinary media.

The foregoing results show that, when a ray is polarized
by reflexion from a crystal, the plane of polarization deviates
from the plane of incidence, except when the axis lies in the
latter plane; and that the deviation may be made very great
by placing the crystal in contact with a medium whose
refractive power is nearly equal to that of the crystal it-
self; for when z is nearly equal to ¢ or to 4, the divisor sin
(t—¢) or sin ({(—9’) is TG small, and therefore tan 6 or

2

108 Mr. Fox’s further Remarks on the Magnetic Forces.

tan 6! is very great. But this remark is of no value whatever
in explaining the very singular phenomena which you have
observed in the extreme case just mentioned ; nor can I ima-
gine any reason why there should be a deviation, as there
was in some of your experiments, when the axis lies in the
plane of incidence, since everything is then alike on both
sides of this plane. Indeed the whole of this subject, which
occupies the latter part of your paper of 1819, is very extra-
ordinary and interesting ; and I was glad to hear that you had
resumed the investigation of it, and made many experiments
which have not been published.

I wish you would publish them. They seem to be of great
importance in the present state of optical science.

Tam, dear Sir, ever truly yours,
Trin, Coll. Dublin, Dec. 22, 1835. J. MacCuiiacuH.

XX. Some further Remarks on the Magnetic Forces. By
R. W. Fox.*

AM glad that Dr. Ritchie has noticed my remarks on the

laws of the magnetic forces, because I hope that it will be
the means of exciting more attention to the subject. I can-
not, however, admit the justness of his conclusion, unless it
can be shown that the results of my experiments are conform-
able to the law of the inverse of the squares of the distances
throughout the whole series of nine or ten removals of the
magnet, calculating from any assumed points whatever in
them. Dr. Ritchie has confined his calculations to only two
or three distances.

The magnets which I employed were cylinders of three
inches long and one tenth of an inch in diameter, and at-
tracted each other with half the force of contact when sepa-
rated about 7,5 of aninch. From this minute distance to
that of } and even +} of an inch, the results were nearlyt in
accordance with the law of the simple inverse ratio of the di-
stance, calculating from the contiguous surfaces of the mag-
nets; and when the same bars were made more strongly
magnetic, their force, at half an inch, much more nearly ap-
proximated to the simple, than to the duplicate, inverse ratio
of the distance.

* Communicated by the Author.

+ Lhave used this qualifying word, because at very minute distances the
diminution of the force did not seem to be quite equal to the inverse
ratio of the distance; whereas it rather exceeded it towards the end of
the series. At the distance of 3 of an inch, the force, in the case referred
to, was about +7',5 of that of contact.

On the Transmission of Calorific Rays. 109

Now, the question is, will it be possible to reconcile these
facts with the latter law ?

I found that when the magnets referred to, adhered to
each other at their terminal edges only, as shown in the
annexed figure, it requized a much greater force
to separate them than when the two surfaces, or
ends a, e, were together. This may, perhaps, be
attributed to a better contact in the former case
than in the latter; and I conceive that if the con-
tact had been still more perfect, the force would
have been reduced one half at less than z;',, of an
inch. The fact, moreover, proves, I think, that the
greatest force of magnets, when in contact at their
dissimilar poles, is not fixed in their axes, or at any
appreciable distance from their points of junction.
Under these circumstances the distribution of their
united forces is, I consider, much the same as it is
in the case of a single magnet. as

XXI. Remarks on M. Melloni’s and Professor Powell’s Papers
on the Transmission of Calorific Rays, inserted in Lond. and.
Edinb. Phil. Mag. for December 1835 and January 1836.
By H. Hupson, M.D., M.R.L.A.*

N referring to the remarks which M. Melloni has done me

the honour to make relative to a communication which

I read to the Physical Section of the British Association}, I

beg to say, that I stated in the paper that I considered my

experiments with the thermo-muitiplier as zmperfect, and

merely mentioned them as indicating a method of determining
a point on which some doubts were still entertained.

I have since adopted the method alluded to, which has fully
confirmed the correctness of M. Melloni’s observations; and
as it appears capable of being advantageously employed in
some branches of the investigation, I shall briefly describe it.
ABCD isa square, mahogany board, on which two rectan-
gular brass plates (each 4 inches wide), E FG H and FILK,
are fixed (as in fig. 1, p. 110,) at right angles to each other and
divided into half inches; at C MI O a plate of brass is fixed
perpendicular to the board, forming a complete screen to T
(the thermo-electric pile), except through a square opening
(at N) equal to the section of the pile. A second brass screen
EI is fixed in like manner perpendicular to the board, and

* Communicated by tke Author.

+ An abstract of the communication here referred to will be found in
Lond. and Edinb. Phil. Mag., vol, vii. p. 297.—Eprr.

110 Dr. H.Hudson’s Remarks on M. Melloni’s and

forming at its base the hypothenuse of the right-angled isosceles
triangle I F E; in this second brass screen there is a circular
opening (P), about 23 inches in diameter, whose centre is im-
mediately opposite to the centre of the square hole (N); both
centres being in the avis of the pile, which is parallel to P Q,
the central line of the brass plate E.G; to this circular opening
a brass circle is attached (moveable round its centre and) having
four screws (as in figure 2.) by means of which any substance
intended to be used asa screen may be firmly fixed in the cir-
cle. Brass plates are made which fit tightly into the circle,

having rectangular pieces (of different sizes) cut out of their
centres. :

c
rt eetho totson Sel Bey

> OE Ti Or CSRS

Having selected one of these plates (in which the opening
is somewhat smaller than the crystal, or other substance in-
tended to be used asa screen) it is fixed into the circle be-
hind the screws (as in figure 3.) and the crystal is then fixed
in front of it so as to completely cover the opening; the bot-
tom of the canister (for containing hot water, &c.) is a right~

Prof. Powell’s Papers on the Transmission of Calorific Rays. 111

angled isosceles triangle, whose equal sides measure four inches,
so that the canister being placed alternately in the different
positions at R and S, it is evident that the lines drawn from
any point of the radiating surface to a given point of the cry-
stal are of equal length, and form the same angle with the cry-
stal and canister in each case; while the other sides of the ca-
nister cannot interfere with the effect. Under these circum-
stances it would appear that any effect produced on the thermo-
multiplier by the mere heating of the crystal should be pre-
cisely; the same in both cases ; and any eacess of effect in the
position R may be taken as the measure of the crystal’s dia-
thermancy for the kind of heat which the canister radiates.
The circle (in which the crystal is fixed) being moveable, the
experiment can be repeated after turning the crystal round
through 180° so as to verify the’ result.

Having made use of the apparatus above described, in ad-
dition to its furnishing abundant confirmation of M. Melloni’s
statements, I think I have obtained a proof that rock crystal
(about 3th of an inch thick) and other bodies, which are
usually considered wholly impervious to the heat radiated from
bodies at low temperatures, do transmit heat from a canister
containing hot water, although the effect is obscured by the
rapidity with which the crystal absorbs heat. I first put the
canister as at S, and the needle almost (if not altogether) zn-
stantaneously begins to move with a slow but rather steady
motion, and at length stops (say) at 5°. The canister being
removed the needle soon settles at zero again. ‘The canister
is then placed at R, and immediately the needle begins to
move (with more energy, however, than in the former case),
and goes to 51°, from which it again returns to about 3°, and
ultimately settles at 5°, as when the canister was at S.

Thus, though there is no perceptible difference in the stati-
cal effect, there appears to be a force acting on the needle at
R (producing a larger are of vibration and in a shorter time)
which, I believe, can only be attributed to rays of heat trans-
mitted through the crystal.

With regard to Professor Powell’s remarks on M. Melloni’s
paper, in the Lond. and Edinb. Phil. Mag. for December,
it appaers to me that the learned Professor has in some de-
gree misapprehended M. Melloni’s observations. Professor
Powell’s ingenious experiment went to prove that rays of heat
issuing from aluminous heated body were transmitted freely,
while those from a non-luminous source were apparently not so
transmitted.

The general fact on which Professor Powell founded the
distinction M.Melloni admits, but he maintains (and on grounds

112 Prof. Powell’s Postscript on the Dispersion of Light.

which I believe to. be incontestably true) that the distinction is
not between Jumznous and obscure sources of heat, but between
the kind of rays of heat emitted from bodies at different zempe-
tures; and that the accident (as I may term it) of the bodies
being at such a temperature that rays of light accompanied
the rays of heat, has nothing whatever to do with the fact of the
different transmissibilities of the calorific rays: 1st, Because the
same difference of transmission exists between sources alto-
gether obscure; 2nd, Because this difference (between lumin-
ous and obscure sources) does not exist with reference to some
bodies, e.g. rock salt; and, thirdly, in bodies emitting light,
the quantity of heat transmitted is in no way proportional,
either to the degree of light which accompanies it in the first
instance, or to the quantity of light which passes through
along with it.

In reference to this subject, it is to be observed, that it is
altogether erroneous to consider “ diathermancy” in the sci-
ence of heat as analogous to * transparency” in optics ; for that
property of bodies by which they stop (absorb) or transmit
rays of a particular refrangibility or colour is the true analogue
in the latter science.

I suspect that this necessary distinction escaped Professor
Powell’s attention when he alluded to M. Melloni’s hypothesis
as “needless and contrary to all analogy ;” for in this view of
the subject, the explanation which M. Melloni has given of
the heat being more abundantly transmitted through succes-
sive plates (of similar natures) is perfectly analogous to the
effect of a succession of screens (of the same colour) on com-
mon light. The “ diathermancy” of rock salt alone appears
entitled to be compared with “ transparency” as used in optics.

Stephen’s Green, Dublin, Jan. 9, 1836.

XXII. On the Theory of Dispersion. By the Rev. B. Powell,
MA., F.R.S., Sav. Prof. of Geometry, Oxford.

EARNING that there is not room in this Number for

the continuation I had proposed of the researches com-

menced in the last, I am anxious meanwhile to make a
brief remark on two points referred to in the last Number.

I. Mr. Tovey in an excellent paper on the formula for di-
spersion, introduces a most material simplification on M. Cau-
chy’s process. I allude to this more particularly now, because
the writer refers to the importance of not omitting the summa-
tion. He will, I trust, find that the introduction of it as
discussed in my paper (and still more when the continuation
appears, ) will produce an entire accordance in our results.

Prof. Powell’s Postscript on the Dispersion of Light. 113

II. In the Editors’ note appended to my paper (p. 28.) there
is a reference to some investigations of M. Rudberg, pub-
lished in a former volume of this Journal. I ought, perhaps,
to have referred to those curious researches at an earlier pe-
riod: but it will readily appear that they are quite distinct
from mine. The author states at the commencement of his
paper: “ In investigating the principle, according to which, for
the explanation of the dispersion of light on the system of
undulations, we must suppose that when the light passes from
the air into a more refractive medium the length of the undu-
lations are much contracted, in fact, much shorter,—I have
found that the following relation appears to exist between the
length of the undulation of a certain colour in the air and
the corresponding one in any other substance :” L = a.1”;
I being the length in air, Lin the medium, @ and m con-
stant depending on the medium.

He then takes Fraunhofer’s value of 7 for each ray, and
assuming that they are diminished in proportion to the re-
fractive power, proceeds to calculate L for the different media
examined by Fraunhofer: and thence the refractive indices
by the formula, which on this assumption follows from the
former (N being the index)

1
N= ope

and the resulting numbers certainly exhibit a very good agree-
ment with those of observation.

Now, with regard to the nature of the formula, it is to be
observed that the author neither gives any theory from which
it is deduced, nor a reference to any other paper, or investiga-
tion of such theory; and the form of it is such as would ap-
pear extremely unlikely to have any connexion with the ana-
lysis of undulations. Again, had any such investigation either
of the author or of any other philosopher been in existence, it
is hardly conceivable that it could have remained since 1827,
without becoming known to some, at least, of the numerous
mathematicians in all parts of Europe who have since that
period been directing their attention to the subject.

But further, (unless I greatly mistake the author’s meaning, )
it appears to me from the very form of expression used in the
passage above quoted, that the formula is not derived from any
theory of undulations: for when, he says, “ In investigating,
&c....... Lhave found, ......” the meaning really seems to me
simply this; that in attempting such an investigation on the
undulatory theory he had not been able to succeed in obtain-
ing any theoretical relation between the yelocity of a waye, and

114 Dr. Faraday’s Experimental Researches in Electricity.

its length: but that EmprricaLty he found upon a compari-
son of numerical results, “ that this relation appears to sub-
sist,” which is expressed by the above formula. Such is the
impression which the passage conveys to my mind; and, in-
deed, the tenor of the whole confirms it. I can only add, that
I should be truly glad to have pointed out any deduction from
theory which would give so simple a formula.

Considered as an empirical law, it certainly merits great
attention. But thus much will be at once evident,—it is totally
independent of M. Cauchy’s principles, and of my results de-
duced and calculated on those principles.

Oxford, Jan. 6, 1836.

XXIII. Experimental Researches in Electricity.—Tenth Se-
ries. By Micuaret Farapay, D.C.L. F.R.S. Fullerian
Prof. Chem. Royal Institution, Corr. Memb. Royal and Imp.
Acadd. of Sciences, Paris, Petersburgh, Florence, Copen-
hagen, Berlin, &c. &c.*

§ 16. On an improved form of the Voltaic Battery. § 17. Some
practical results respecting the construction and use of the
Voltaic Battery.

1119; l HAVE lately had occasion to examine the voltaic

trough practically, with a view to improvements in
its construction and use; and though I do not pretend that the
results have anything like the importance which attaches to
the discovery of a new law or principle, I still think they are
valuable, and may therefore, if briefly told, and in connexion
with former papers, be worthy the approbation of the Royal
Society.

§ 16. On an improved form of the Voltaic Battery.

1120. In a simple voltaic circuit (and the same is true of
the battery) the chemical forces which, during their activity,
give power to the instrument, are generally divided into two
portions; the one of these is exerted locally, whilst the other
is transferred round the circle (947. 996.) ; the latter consti-
tutes the electric current of the instrument, whilst the former
is altogether lost or wasted. ‘The ratio of these two portions
of power may be varied to a great extent by the influence of
circumstances: thus, in a battery not closed, all the action is
local; in one of the ordinary construction, much is in circula-

* From the Philosophical Transactions for 1835, Part [I]. This paper was
received by the Royal Society June 16th, and read June 18th, 1835.

[+ The paragraphs of the author’s former series of Researches here refer-
red to, from 875 to 1047 both inclusive, belong to his Eighth Series, re-
printed in Lond, and Edinb, Phil. Mag., vol. vi. p. 34 et seg. —Enir. ]

On an improved Form of the Voltaic Battery. 115

tion when the extremities are in communication; and in the
perfect one, which I have described (1001.), ad/ the chemical
power circulates and becomes electricity. By referring to the
quantity of zinc dissolved from the plates (865.* 1126.), and
the quantity of decomposition effected in the volta-electrometer
(711. 1126.) or elsewhere, the proportions of the local and
transferred actions under any particular circumstances can be
ascertained, and the efficacy of the voltaic arrangement, or the
waste of chemical power at its zinc plates, be accurately deter-
mined.

1121. Ifa voltaic battery were constructed of zine and pla-
tina, the latter metal surrounding the former, as in the double
copper arrangement, and the whole being excited by dilute
sulphuric acid, then no insulating divisions of glass, porcelain,
or air would be required between the contiguous platina sur-
faces ; and, provided these did not touch metallically, the same
acid which, being between the zinc and platina, would excite
the battery into powerful action, would, between the two sur-
faces of platina, produce no discharge of the electricity, nor
cause any diminution of the power of the trough. ‘This is a
necessary consequence of the resistance to the passage of the
current which I have shown occurs at the place of decompo-
sition (1007. 1011.); for that resistance is fully able to stop the
current, and therefore act as insulation to the electricity of the
contiguous plates, in as much as the current which tends to pass
between them never has a higher intensity than that due to the
action of a single pair.

1122. If the metal surrounding the zinc be copper (1045.),
and if the acid be nitrosulphuric acid (1020.), then a slight
discharge between the two contiguous coppers does take place,
provided there be no other channel open by which the forces
may circulate: but when such a channel is permitted, the re-
turn discharge of which I speak is exceedingly diminished, in
accordance with the principles laid down in the eighth series of
these Researches.

1123. Guided by these principles I was led to the construc-
tion of a voltaic trough, in which the coppers, passing round
both surfaces of the zincs, as in Wollaston’s construction,
should not be separated from each other except by an inter-
vening thickness of paper, or in some other way, so as to pre-
vent metallic contact, and should thus constitute an instrument
compact, powerful, economical, and easy of use. On examin-
ing, however, what had been done before, I found that the

(* The paragraphs referred to from 661 to 874 will be found in Mr. Fa-
raday’s Seventh Series, reprinted in Lond. and Edinb. Phil. Mag., vol. y.
p- 161, et seq.—En1r. |

116 Dr. Faraday’s Experimental Researches in Electricity.

new trough was in all essential respects the same as that in-
vented and described by Dr. Hare, Professor in the Univer-
sity of Pennsylvania, to whom I have great pleasure in re-
ferring it.

1124. Dr. Hare has fully described his trough*. In it the
contiguous copper plates are separated by thin veneers of
wood, and the acid is poured on to, or off, the plates by a
quarter revolution of an axis, to which both the trough con-
taining the plates, and another trough to collect and hold the
liquid, are fixed. ‘This arrangement I have found the most
convenient of any, and have therefore adopted it. My zinc
plates were cut from rolled metal, and when soldered to the
copper plates had the form delineated, fig. 1. These were
then bent over a gauge into the form fig. 2., and when packed
in the wooden box constructed to receive them, were arranged
as in fig. 34, little plugs of cork being used to keep the zine

Fig. 1.

plates from touching the copper plates, and a single or double
thickness of cartridge paper being interposed between the con-
tiguous surfaces of copper to prevent them from coming in
contact. Such wes the facility afforded by this arrangement,
that a trough of forty pairs of plates could be unpacked
in five minutes, and repacked again in half an hour; and the
whole series was not more than fifteen inches in length.

1125. This trough, of forty pairs of plates three inches

* Philosophical Magazine, 1824, vol. Ixiii. p. 241; or Silliman’s Journal,
vol. vii. See also a previous paper by Dr. Hare, Annals of Philosophy
[Second Series], 1821, vol. i. p. 329, [also Phil. Mag., First Series, vol. lvii.
p- 284.] in which he speaks of the non-necessity of insulation between the
coppers.

+ The papers between the coppers are, for the sake of distinctness,
omitted in the figure,

Estimation of Voltaic Energy by Equivalents. 117

square, was compared, as to the ignition of a platina wire, the
discharge between points of charcoal, the shock on the human
frame, Xc., with forty pairs of four-inch plates having double
coppers, and used in porcelain troughs divided into insulating
cells, the strength of the acid employed to excite both being
the same. Inall these effects the former appeared quite equal
to the latter. On comparing a second trough of the new con-
struction, containing twenty pairs of four-inch plates, with
twenty pairs of four-inch plates in porcelain troughs, excited
by acid of the same strength, the new trough appeared to sur-
pass the old one in producing these effects, especially in the
ignition of wire.

1126. In these experiments the new trough diminished in
its energy much more rapidly than the one on the old con-
struction; and this was a necessary consequence of the smaller
quantity of acid used to excite it, which in the case of the forty
pairs new construction was only one seventh part of that used
for the forty pairs in the porcelain troughs. ‘To compare,
thérefore, both forms of the voltaic trough in their decompos-
ing powers, and to obtain accurate data as to their relative
values, experiments of the following kind were made. ‘The
troughs were charged with a known quantity of acid of a
known strength; the electric current was passed through a
volta-electrometer (711.) having electrodes 4 inches long and
23 inches in width, so as to oppose as little obstruction as
possible to the current; the gases evolved were collected and
measured, and gave the quantity of water decomposed. Then
the whole of the charge used was mixed together, and a known
part of it analysed, by being precipitated and boiled with ex-
cess of carbonate of soda, and the precipitate well washed,
dried, ignited, and weighed. In this way the quantity of metal
oxidized and dissolved by the acid was ascertained; and the
part removed from each zinc plate, or from all the plates, could
be estimated and compared with the water decomposed in the
volta-electrometer. ‘To bring these to one standard of com-
parison, I have reduced the results so as to express the loss
at the plates in equivalents of zinc for the equivalent of water
decomposed at the volta-electrometer: I have taken the equi-
valent number of water as 9, and of zinc as 32°5, and have
considered 100 cubic inches of the mixed oxygen and hydro-
gen, as they were collected over a pneumatic trough, to result
from the decomposition of 12°68 grains of water.

1127. The acids used in these experiments were three,—sul-
phuric, nitric, and muriatic. The sulphuric acid was strong
oil of vitriol ; one cubical inch of it was equivalent to 486 grains
of marble. The nitric acid was very nearly pure; one cubical
inch dissolved 150 grains of marble. The muriatic acid was

118 Dr. Faraday’s Experimental Researches in Electricity.

also nearly pure, and one cubical inch dissolved 108 grains of
marble. These were always mixed with water by volumes,
the standard of volume being a cubical inch.

1128. An acid was prepared consisting of 200 parts water,
41 parts sulphuric acid, and 4 parts nitric acid ; and with this
both my trough, containing forty pairs of three-inch plates,
and four porcelain troughs, arranged in succession, each con-
taining ten pairs of plates with double coppers four inches
square, were charged. These two batteries were then used
in succession, and the action of each was allowed to continue
for twenty or thirty minutes, until the charge was nearly ex-
hausted, the connexion with the volta-electrometer being care-
fully preserved during the whole time, and the acid in the
troughs occasionally mixed together. In this way the former
trough acted so well, that for each equivalent of water decom-
posed in the volta-electrometer only from 2 to 2°5 equivalents
of zinc were dissolved from each plate. In four experiments
the average was 2°21 equivalents for each plate, or 88°4 for the
whole battery. In the experiments with the porcelain troughs,
the equivalents of consumption at each plate were 3°54, or
141°6 for the whole battery. In a perfect voltaic battery of
forty pairs of plates (991. 1001.) the consumption would have
been one equivalent for each zinc plate, or forty for the whole.

1129. Similar experiments were made with two voltaic
batteries, one containing twenty pairs of four-inch plates, ar-
ranged as I have described (1124.), and the other twenty pairs
of four-inch plates in porcelain troughs. The average of five
experiments with the former was a consumption of 3°7 equiva-
lents of zinc from each plate, or 74 from the whole: the average
of three experiments with the latter was 5°5 equivalents from
each plate, or 110 from the whole: to obtain this conclusion,
two experiments were struck out, which were much against
the porcelain troughs, and in which some unknown deteriorat-
ing influence was supposed to be accidentally active. In all
the experiments, care was taken not to compare zew and old
plates together, as that would have introduced serious errors
into the conclusions (1146.).

1130. When ten pairs of the new arrangement were used,
the consumption of zinc at each plate was 6°76 equivalents, or
67°6 for the whole. With ten pairs of the common construc-
tion, in a porcelain trough, the zinc oxidized was, upon an
average, 15°5 equivalents each plate, or 155 for the entire
trough.

1131. No doubt, therefore, can remain of the equality or
even the great superiority of this form of voltaic battery over
the best previously in use, namely, that with double coppers,
in which the cells are insulated. The insulation of the cop-

Advantages of Hare’s Trough. 119

pers may therefore be dispensed with; and it is that circum-
stance which principally permits of such other alterations in
the construction of the trough as gives it its practical advan-
tages.

1132. The advantages of this form of trough are very nu-
merous and great. i. It is exceedingly compact, for 100 pairs
of plates need not occupy a trough of more than three feet in
Jeneth. ii. By Dr. Hare’s plan of making the trough turn
upon copper pivots which rest upon copper bearings, the latter
afford fixed terminations; and these I have found it very con-
venient to connect with two cups of mercury, fastened in the
front of the stand of the instrument. These fixed terminations
give the great advantage of arranging an apparatus to be used
in connexion with the battery before the latter is put into ac-
tion. iii. The trough is put into readiness for use in an instant,
a single jug of dilute acid being sufficient for the charge of
100 pairs of four-inch plates. iv. On making the trough pass
through a quarter of a revolution, it becomes active, and the
great advantage is obtained of procuring for the experiment
the effect of the first contact of the zinc and acid, which is
twice or sometimes even thrice that which the battery can pro-
duce a minute or two after (1036. 1150.). v. When the ex-
' periment is completed, the acid can be at once poured from
between the plates, so that the battery is never left to waste
during an unconnected state of its extremities ; the acid is not
unnecessarily exhausted; the zinc is not uselessly consumed ;
and, besides avoiding these evils, the charge is mixed and ren-
dered uniform, which produces a great and good result (1039.);
and, upon proceeding to a second experiment, the important
effect of first contact is again obtained. vi. The saving of zinc
is very great. It is not merely that, whilst in action, the zinc
performs more voltaic duty (1128. 1129.), but a// the destruc-
tion which takes place with the ordinary forms of battery be-
tween the experiments is prevented. This saving is of such
extent that I estimate the zinc in the new form of battery to
be thrice as effective as that in the ordinary form. vii. The
importance of this saving of metal is not merely that the value
of the zinc is saved, but that the battery is much lighter and
more manageable; and also that the surfaces of the zinc and
copper plates may be brought much nearer to each other when
the battery is constructed, and remain so until it is worn out:
the latter is a very important advantage (1148.). viii, Again,
as, in consequence of the saving, thinner plates will perform
the duty of thick ones, rolled zinc may be used; and I have
found rolled zinc superior to cast zinc in action ; a superiority
which I incline to attribute to its greater purity (1144.).
ix. Another advantage is obtained in the economy of the acid

120 Dr. Faraday’s Experimental Researches in Electricity.

used, which is proportionate to the diminution of the zinc dis-
solved. x. The acid also is more easily exhausted, and is
in such small quantity that there is never any occasion to re-
turn an old charge into use. Such old acid, whilst out of use,
often dissolves portions of copper from the black flocculi usu-
ally mingled with it, which are derived from the zinc; now any
portion of copper in solution in the charge does great harm,
because, by the local action of the acid and zinc, it tends
to precipitate upon the latter, and diminish its voltaic efficacy
(1145.). xi. By using a due mixture of nitric and sulphuric
acid for the charge (1139.), no gas is evolved from the troughs;
so that a battery of several hundred pairs of plates may, with-
out inconvenience, be close to the experimenter. xii. If, dur-
ing a series of experiments, the acid becomes exhausted, it can
be withdrawn, and replaced by other acid with the utmost fa-
cility ; and after the experiments are concluded, the great ad-
vantage of easily washing the plates is at command. And it
appears to me, that in place of making, under different circum-
stances, mutual sacrifices of comfort, power, and economy, to
obtain a desired end, all are at once obtained by Dr. Hare’s
form of trough.

1133. But there are some disadvantages which I have not
yet had time to overcome, though I trust they will finally be
conquered. One is the extreme difficulty of making a wooden
trough constantly water-tight under the alternations of wet
and dry to which the voltaic instrument is subject. To remedy
this evil, Mr. Newman is now engaged in obtaining porcelain
troughs. The other disadvantage is a precipitation of copper
on the zinc plates. It appears to me to depend mainly on the
circumstance that the papers between the coppers retain acid
when the trough is emptied; and that this acid slowly acting
on the copper, forms a salt, which gradually mingles with the
next charge, and is reduced on the zinc plate by the local ac-
tion (1120.): the power of the whole battery is then reduced.
I expect that by using slips of glass to separate the coppers at
their edges, their contact can be sufficiently prevented, and the
space between them be left so open that the acid ofa charge can
be poured and washed out, and so be removed from every part:
of the trough when the experiments in which it is used are
completed.

1134. The actual superiority of the troughs which I have
constructed on this plan, I believe to depend, first and prin-
cipally, on the closer approximation of the zinc and copper
surfaces ;—in my troughs they are only one tenth of an inch
apart (1148.) ;—and, next, on the superior quality of the rolled
zinc above the cast zinc used in the construction of the ordi-
nary pile. It cannot be that insulation between the contigu-

Nature and Strength of the Battery Acid. 121

ous coppers is a disadvantage, but I do not find that it is any
advantage; for when, with both the forty pairs of three-inch
plates and the twenty pairs of four-inch plates, I used papers
well imbibed with wax%, these being so large that when folded
at the edges they wrapped over each other, so as to make cells
as insulating as those of the porcelain troughs, still no sensible
advantage in the chemical action was obtained.

1185. As, upon principle, there must be a discharge of
part of the electricity from the edges of the zinc and copper
plates at the sides of the trough, I should prefer, and intend
having, troughs constructed with a plate or plates of crown
glass at the sides of the trough: the bottom will need none,
though to glaze that and the ends would be no disadvantage,
The plates need not be fastened in, but only set in their places ;
nor need they be in large single pieces.

§ 17. Some practical results respecting the construction and use
of the Voltaic Battery.

1136. The electro-chemical philosopher is well acquainted
with some practical results obtained from the voltaic battery
by MM. Gay-Lussac and Thenard, and given in the first forty-
five pages of their Recherches Physico-chimiques. Although
the following results are generally of the same nature, yet the
advancement made in this branch of science of late years, the
knowledge of the definite action of electricity, and the more
accurate and philosophical mode of estimating the results by
the equivalents of zinc consumed, will be their sufficient justi-
fication.

1137. Nature and strength of the acid.—My battery of forty
pairs of three-inch plates was charged with acid consisting of
200 parts water and 9 oil of vitriol. Each plate lost, in the
average of the experiments, 4°66 equivalents, or the whole
battery 186°4 equivalents, of zinc, for the equivalent of water
decomposed in the volta-electrometer. Being charged with
a mixture of 200 water and 16 of the muriatic acid, each plate
lost 3°8, or the whole battery 152, equivalents of zinc for the
water decomposed. Being charged with a mixture of 200
water and 8 nitric acid, each plate lost 1°35, or the whole bat-
tery 74°16, equivalents of zinc for one equivalent of water de-
composed. ‘The sulphuric and muriatic acids evolved much
hydrogen at the plates in the trough; the nitric acid no gas
whatever. ‘he relative strengths of the original acids have
already been given (1127.); but a difference in that respect

* A single paper thus prepared could insulate the electricity of a trough
of forty pairs of plates.
Third Series, Vol. 8. No. 45. Feb, 1836.

‘192 Dr. Faraday’s Experimental Researches in Electricity.

makes no important difference in the results when thus.ex-
pressed by equivalents (1140.).

1138. Thus nitric acid proves to be the best for this purpose:
its superiority appears to depend upon its favouring the elec-
trolization of the liquid in the cells of the trough upon the
principles already explained (905. 973. 1022.), and conse-
quently favouring the transmission of the electricity, and there-
fore the production of transferable power (1120.).

1139. The addition of nitric acid might, consequently, be
expected to improve sulphuric and muriatic acids. Accord-
ingly, when the same trough was charged with a mixture of
200 water, 9 oil of vitriol, and 4 nitric acid, the consumption
of zinc was at each plate 2°786, and for the whole battery
111°5 equivalents. When the charge was 200 water, 9 oil of
vitriol, and 8 nitric acid, the loss per plate was 2°26, or for the
whole battery 90°4, equivalents. When the trough was
charged with a mixture of 200 water, 16 muriatic acid, and 6
nitric acid, the loss per plate was 2°11, or for the whole battery
84°4, equivalents. Similar results were obtained with my bat-
tery of twenty pairs of four-inch plates (1129.). Hence it is
evident that the nitric acid was of great service when mingled
with the sulphuric acid; and the charge generally used after
this time for ordinary experiments consisted of 200 water, 4
oil of vitriol, and 4 nitric acid.

1140. It is not to be supposed that the different strengths
of the acids produced the differences above ; for within certain
limits I found the electrolytic effects to be nearly as the strengths
of the acids, so as to leave the expression of force, when given
in equivalents, nearly constant. Thus, when the trough was
charged with a mixture of 200 water and 8 nitric acid, each
plate lost 1°854 equivalent of zinc. When the charge was
200 water and 16 nitric acid, the loss per plate was 1°82 equi-
valent. When it was 200 water and 32 nitric acid, the loss
was 2°1 equivalents. The differences here are not greater
than happen from unavoidable irregularities, depending on
other causes than the strength of acid. .

1141. Again, when a charge consisting of 200 water, 43 oil
of vitriol, and 4 nitric acid was used, each zinc plate lost 2°16
equivalents; when the charge with the same battery was 200
water, 9 oil of vitriol, and 8 nitric acid, each zinc plate lost
2°26 equivalents.

1142. I need hardly say that no copper is dissolved during
the regular action of the voltaic trough. I have found that
much ammonia is formed in the cells when nitric acid, either
pure or mixed with sulphuric acid, is used. It is produced in
part as a secondary result at the cathodes (663.) of the dif-

74

Uniformity of the Charge.—New and old Plates. 123

ferent portions of fluid constituting the necessary electrolyte,
in the cells.

1143. Uniformity of the charge.—This is a most important
point, as I have already shown experimentally (1042. &c.).
Hence one great advantage of Dr. Hare’s mechanical arrange-
ment of his trough.

1144. Purity of the zinc.—If pure zinc could be obtained,
it would be very advantageous in the construction of the vol- -
taic apparatus (998.). . Most zincs, when put into dilute sul-
phuric acid, leave more or less of an insoluble matter upon
the surface in the form of a crust, which contains various me-
tals, as copper, lead, zinc, iron, cadmium, &c., in the metallic
state. Such particles, by discharging part of the transferable
power, render it, as to the whole battery, local; and so dimi-
nish the effect. As an indication connected with the more or
less perfect action of the battery, I may mention that no gas
ought to rise from the zinc plates. ‘The more gas which is
generated upon these surfaces, the greater is the local action
and the less the transferable force. ‘The investing crust is also
inconvenient, by preventing the displacement and renewal of
the charge upon the surface of the zinc. Such zinc as, dis-
solving in the cleanest manner in a dilute acid, dissolves also
the slowest, is the best; zinc which contains much copper
should especially be avoided. I have generally found rolled
Liege or Mosselman’s zinc the purest; and to that circum-
stance attribute in part the advantage of the new battery
(1134.).

1145. Foulness of the zinc plates.—After use, the plates of
a battery should be cleaned from the metallic powder upon
their surfaces, especially if they are employed to obtain the
laws of action of the battery itself. This precaution was al-
ways attended to with the porcelain trough batteries in the
experiments described (1125. &c.). If a few foul plates. are
mingled with many clean ones, they make the action in the
different cells irregular, and the transferable power is-accord-
ingly diminished, whilst the local and wasted power is in-
creased. No old charge containing copper should be used to
excite a battery.

_ 1146. New and old plates.—I1 have found voltaic batteries
far more powerful when the plates were new than when they
have been used two or three times; so that a new and a used
battery cannot be compared together, or even a battery with
itself on the first and after times of use. My trough of twenty
pairs of four-inch plates, charged with acid consisting of 200
water, 4} oil of vitriol, and 4 nitric acid, lost, upon the first
time of being used, 2°32 sane per plate. When used
2

124 Dr. Faraday’s Experimental Researches in Electricity.

after the fourth time with the same charge, the loss was from
3°26 to 4°47 equivalents per plate; the average being 3°7 equi-
valents. The first time the forty pair of plates (1124.) were
_ used, the loss at each plate was only 1°65 equivalent; but
afterwards it became 2°16, 2°17, 2°52. The first time twenty
pair of four-inch plates in porcelain troughs were used, they
lost, per plate, only 3°7 equivalents; but after that, the loss
was 5°25, 5°36, 5°9 equivalents. Yet in all these cases the
zincs had been well cleaned from adhering copper, &c., before
each trial of power.

1147. With the rolled zinc the fall in force soon appeared
to become constant, i. e. to proceed no further. But with the
cast zinc plates belonging to the porcelain troughs, it appeared
to continue, until at last, with the same charge, each plate lost
above twice as much zinc for a given amount of action as at
first. These troughs were, however, so irregular that I could
not always determine the circumstances affecting the amount
of electrolytic action.

1148. Vicinity of the copper and zinc.—The importance of
this point in the construction of voltaic arrangements, and the
greater power, as to immediate action, which is obtained when
the zinc and copper surfaces are near to each other than when
removed further apart, are well known. I find that the power
is not only greater on the instant, but also that the sum of
transferable power, in relation to the whole sum of chemical
action at the plates, is much increased. The cause of this gain
is very evident. Whatever tends to retard the circulation of
the transferable force, (i. e. the electricity, ) diminishes the pro-
portion of such force, and increases the proportion of that
which is local (996. 1120.). Now the liquid in the cells pos-
sesses this retarding power, and therefore acts injuriously, in
greater or less proportion, according to the quantity of it be-
tween the zinc and copper plates, i.e. according to the di-
stances between their surfaces. A trough, therefore, in which
the plates are only half the distance asunder at which they are
placed in another, will produce more transferable, and less
local, force than the latter; and thus, because the electrolyte
in the cells can transmit the current more readily, both the
intensity and quantity of electricity is increased for a given
consumption of zinc. To this circumstance mainly I attribute
the superiority of the trough I have described (1134.).

1149. The superiority of double coppers over single plates
also depends in part upon diminishing the resistance offered
by the electrolyte between the metals. For, in fact, with dou-
ble coppers the sectional area of the interposed acid becomes
nearly double that with single coppers, and therefore it more

First Immersion of the Plates—Their Number. 125

freely transfers the electricity. Double coppers are, however,
effective, mainly because they virtually double the acting sur-
face of the zinc, or nearly so; for in a trough with single cop-
per plates and the usual construction of cells, that surface of
zine which is not opposed to a copper surface is thrown almost
entirely out of voltaic action, yet the acid continues to act
upon it and the metal is dissolved, producing very little more
than local effect (947. 996.). But when by doubling the cop-
per, that metal is opposed to the second surface of the zinc
plate, then a great part of the action upon the latter is con-
verted into transferable force, and thus the power of the
trough as to quantity of electricity is highly exalted.

1150. First immersion of the plates.—The great effect pro-
duced at the first immersion of the plates, (apart from their
being new or used (1146.),) I have attributed elsewhere to the
unchanged condition of the acid in contact with the zinc plate
(1003. 1037.): as the acid becomes neutralized, its exciting

‘power is proportionably diminished. Hare’s form of trough
secures much advantage of this kind, by mingling the liquid,
and bringing what may be considered as a fresh surface of
acid against the plates every time it is used immediately after
a rest.

1151. Number of plates*.—The most advantageous num-
ber of plates in a battery used for chemical decomposition,
depends almost entirely upon the resistance to be overcome at
the place of action; but whatever that resistance may be,
there is a certain number which is more ceconomical than
either a greater or a less. Ten pairs of four-inch plates in a
porcelain trough of the ordinary construction, acting in the
volta-electrometer (1126.) upon dilute sulphuric acid of spec.
gray. 1°314, gave an average consumption of 15:4 equivalents
per plate, or 154 equivalents on the whole. Twenty pairs of
the same plates, with the same acid, gave only a consump-
tion of 5°5 per plate, or 110 equivalents upon the whole.
When forty pairs of the same plates were used, the consump-
tion was 3°54 equivalents per plate, or 141°6 upon the whole
battery. Thus the consumption of zinc arranged as twenty
plates was more advantageous than if arranged either as ten
or as forty.

1)52. Again, ten pairs of my four-inch plates (1129.) lost
6°76 each, or the whole ten 67°6 equivalents of zinc, in effect-
ing decomposition; whilst twenty pairs of the same plates,
excited by the same acid, lost 3°7 equivalents each, or on the
whole 74 equivalents. In other comparative experiments of
numbers, ten pairs of the three-inch plates (1125.) lost 3°725,

* Gay-Lussac and Thenard, Recherches Physico-chimiques, tom. i. p. 29.

126 Dr. Faraday’s Experimental Researches in Electricity.

or 37°25 equivalents upon the whole; whilst twenty pairs lost
2°53 each, or 50°6 in all; and forty pairs lost on an average
2°21, or 88°4 altogether. In both these cases, therefore, in-
crease of numbers had not been advantageous as to the effec-
tive production of transferable chemical power from the whole
quantity of chemical force active at the surfaces of excitation
1120.).

1153. But if I had. used a weaker acid or a worse con-
ductor in the volta-electrometer, then the number of plates
which would produce the most advantageous effect would
have risen; or if I had used a better conductor than that
really employed in the volta-electrometer, I might have re-
duced the number even to one; as, for instance, when a thick
wire is used to complete the circuit (865. &c.). And the
cause of these variations is very evident, when it is considered
that each successive plate ‘in the voltaic apparatus does not
add anything to the quantity of transferable power or electri-
city which the first plate can put into motion, provided a good
conductor be present, but tends only to exalt the zntenszty of
that quantity, so as to make it more able to overcome the ob-
struction of bad conductors (994. 1158.).

1154. Large or small plates*.—The advantageous use of
large or small plates for electrolyzations will evidently depend
upon the facility with which the transferable power or electri-
city can pass. If in a particular case the most effectual num-
ber of plates is known (1151.), then the addition of more zine
would be most advantageously made in increasing the size of
the plates, and not their number. At the same time, large
increase in the size of the plates would raise in a small degree
the most favourable number.

1155. Large and small plates should not be used together
in the same battery: the small ones occasion a loss of the
power of the large ones, unless they be excited by an acid
proportionably more powerful; for with a certain acid they
cannot transmit the same portion of electricity in a given
time which the same acid can evolve by action on the larger
plates.

1156. Simultaneous decompositions. When the number of
plates in a battery much surpasses the most favourable pro-
portion (1151—1153.), two or more decompositions may be
effected simultaneously with advantage. ‘Thus my forty pairs
of plates (1124.) produced in one volta-electrometer 22°8
eubic inches of gas. Being recharged exactly in the same
manner, they produced in each of two volta-electrometers 24

* Gay-Lussac and Thenard, Recherches Physico-chimiques, tom. i. p. 29.

Effect of largeand smallPlates : Simultaneous Decompositions.127

cubical inches. In the first experiment the whole consump-
tion of zinc was 88"4 equivalents, and in the second only
48°28 equivalents, for the whole of the water decomposed in
both volta-electrometers.

1157. But when the twenty pairs of four-inch plates (1129.)
were tried in a similar manner, the results were in the oppo-
site direction. With one volta-electrometer 52 cubic inches
of gas were obtained; with two, only 14°6 cubic inches from
each. The quantity of charge was not the same in both cases,
though it was of the same strength ; but on rendering the re-
sults comparative by reducing them to equivalents (1126.),
+t was found that the consumption of metal in the first case
was 74, and in the second case 97, equivalents for the whole
of the water decomposed. These results of course depend
upon the same circumstances of retardation, &c., which have
been referred to in speaking of the proper number of plates
(1151.).

1158. That the transferring, or, as it is usually called, con-
ducting, power of an electrolyte which is to be decomposed,
or other interposed body, should be rendered as good as pos-
sible*, is very evident (1020. 1120.). With a perfectly good
conductor and a good battery, nearly all the electricity is
passed, i. e. nearly all the chemical power becomes transfer-
able, even with a single pair of plates (867.). With an inter-~
posed non-conductor none of the chemical power becomes
transferable. With an imperfect conductor more or less of
the chemical power becomes transferable as the circumstances
favouring the transfer of forces across the imperfect conductor
are exalted or diminished: these circumstances are, actual
increase or improvement of the conducting power, enlarge-
ment of the electrodes, approximation of the electrodes, and
increased intensity of the passing current.

1159. The introduction of common spring water in place
of one of the volta-electrometers used with twenty pairs of
four-inch plates (1156.) caused such obstruction as not to al-
low one fifteenth of the transferable force to pass which would
have circulated without it. Thus fourteen fifteenths of the
available force of the battery were destroyed, being converted
into local force, (which was rendered evident by the evolution
of gas from the zines,) and yet the platina electrodes in the
water were three inches long, nearly an inch wide, and not
a quarter of an inch apart.

1160. These points, i. e. the increase of conducting power,

* Gay-Lussac and Thenard, Recherches Physico-chimiques, tom. i. pp. 13,

15, 22.

128 Mr. Grant on protecting Iron from the Action of Salt Water.

the enlargement of the electrodes, and their approximation,
should be especially attended to in volta-electrometers. The
principles upon which their utility depend are so evident that
there can be no occasion for further development of them
here. Me:

Royal Institution, Oct. 11, 1834.

XXIV. Experiments on the Protection of Iron from the
Action of Salt-Water. By 'T. Tassert Grant, Esq.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

wits reference to the interesting papers which appear

in your Journal of the present month (November 1835,
vol. vii. pp. 389, 391.) giving an account of som eexperiments
recently made with the view of protecting iron from the action
of salt water, &c., I beg leave to communicate, that for some
months past I have myself been engaged in a series of very si-
milar experiments. My attention was drawn to the subject with
the view of obtaining a remedy for the great wear and tear arising
from the oxidation of the iron tanks at present generally used in
the Navy for the stowage of fresh water. I first fitted a small
plate of zinc, 3 inches square, ;';th of an inch thick, with iron
rivets, to a piece of sheet iron 6 inches square, the two metals
being completely in contact, and immersed the same into six
gallons of spring water ; at the same time I also immersed a
piece of sheet iron of the same dimensions, without the zinc,
into the same quantity and quality of water: at the expiration
of thirty days the two pieces of iron presented nearly the
same appearance, viz. oxidation was perceivable, and to the
same extent in both. I repeated the experiment with pro-
tectors of larger dimensions, still without any satisfactory re-
sult; and I have other experiments still in progress, in which
the two metals bear a more equal proportion, but sufficient
time has. not yet elapsed to form a correct opinion as to the
result. Experiments with the two metals in contact in salt
water, for the purpose of substituting iron sheathing for ships’
bottoms instead of copper, have also engaged my attention,
and have been attended with various results. As far as these
experiments have proceeded, I fear they are not likely to be
productive of the great benefit I at first anticipated. Although
no doubt can exist as to the zinc protecting the iron from
oxidation, as the simple electrical action arising by the con-
tact of the two metals in presence of the fluid will produce
that effect, yet I have found in all instances that the cor-

Mr. Grant on protecting Iron from the Action of Salt Water. 129

rosion of the zinc is very considerable: the following expe-
riment will show to what extent: Two pieces of sheet iron
fastened to a piece of wood, the one with nine zinc nails, the
other with the same number of iron nails having pieces of
zinc $ths of an inch in diameter under the head of each nail ;
also a third piece of sheet iron fastened to the wood simply
with iron nails: the board was then floated in the sea, and at
the expiration of thirty days, I found that the heads of six of
the nine zinc nails had completely disappeared, and the pieces
of zinc corroded to such an extent that only a very small por-
tion of zinc remained. The protected iron down to this period
was free from oxidation, whereas the iron unprotected was
perfectly oxidized. This experiment has been repeated several
times with the same result, which clearly shows that although
the zinc completely protected the iron, the zinc itself became
corroded in exact proportion to the protection that it afforded to
the iron. Experiment has also proved that the same evil which
rendered Sir Humphry Davy’s system of no practical use for
the protection of copper on ships’ bottoms from oxidation, is
also apparent to a certain extent as regards the protected
iron ; viz. that by rendering it slightly negative, a calcareous
substance is found deposited on its surface; and that sea ve-
getable matter appeared also in a short period to attach itself
to the iron, although in a much less degree than in the expe-
riments tried on the bottoms of boats which were subject to
the constant friction of the water passing by them.

In the experiments tried in still water, vegetable matter
was found to make its appearance on the iron in six weeks
after immersion, although a strong electrical current was
kept up during that period. The results of the experiments,
as far as they have proceeded, lead me, therefore, to the fol-
lowing conclusions: in the first place, that iron and zinc in
connexion will not protect the former from oxidation in fresh
water; secondly, that when iron and zinc are in connexion in
salt water, the iron will be protected, but a calcareous and
vegetable matter is generated upon it; and, thirdly, that in
the same proportion as the zinc protects the iron, the zinc it-
self becomes subject to corrosion.

I wish it, however, to be clearly understood, that although
these experiments are not so favourable as might be wished,
I by no means consider them so conclusive as to preclude
the necessity of further investigation.

I am, Gentlemen, yours, &c.

Royal Clarence Yard, Gosport, Tuomas TassELL Grant.
November 22, 1835.

car awit [ 430 Ji a

XXV. On the Conducting Power of Iodine, Bromine, and
Chlorine for Electricity. By Epwarp Souty, Jun., Esq.*

QW the Philosophical Magazine and Journal of Science;
No. 42, p. 441, Dr. Inglis, in his prize essay on iodine,
states that he has found solid iodine to be a conductor of elec-
tricity. In my own observations I had always found it a non-
conductor ; I was therefore led to repeat my experiments with
greater care, and the following are the results.

1. I first sought for conducting power by the beautiful me-
thod proposed by Dr. Wollaston, namely, the effect produced
upon the tongue when two metals of different degrees of oxi-
dibility, placed on either side of it, are made to communicate
with each other, through any portion of conducting matter.
lodine was melted in a thin glass tube, which, when cold, was
broken, and the iodine obtained in a solid state ; a portion was
then placed between the extremities of the two metals; but on
no occasion was the least taste produced ; though if the metals
were connected together only by being immersed in spring
water, a taste was immediately perceived. When the two
terminations of the metal plates are made to dip into 2 solution
of iodine in water, a strong taste is perceived.

2. In order to examine the conducting power with the vol-
taic battery, and where the application of the tongue would
have been uncertain and inconvenient, the following apparatus
was used. BD J K is a slip of glass, on which two pieces
of bibulous paper, E and F, soaked in a solution of iodide of
potassium, are placed. The wire A, resting upon E, was al-
ways made the anode C; or that resting an F, the cathode:
thus arranged, of course no action. took place. But if a wire
was made to touch with one end the paper F, and with the
other end the paper E, the usual series of pheenomena took
place ; iodine was evolved at A, and also at that end of the tem-
porary wire which rested upon F. The fluid to be examined
was placed in a glass tube, G, having two platinum wires, H
and I, fused into it; they were separated from each other by
an interval of about the jth of an inch; thus, when the two
wires were made to rest upon the two pieces of paper F and

* Communicated by the Author.—It appears that we were correct in
thinking that Dr. Inglis’s experiments on this subject would attract atten-
tion. He has favoured us with the following reply to our note respecting
it appended to the first part of his paper, as referred to above. “In answer
to the note regarding the conducting power of iodine, I may just quote a
sentence from my original Essay: ‘The preparation sent in, shows the state
in which iodine requires to be, for the transmission of Electricity. It has
merely been fused in a glass tube, and the tube afterwards broken from
around it. But although it still continues to conduct, it did so with far
more energy when in the fluid state.’ Dec. 18, 1835.”—Enrr.

On the Conducting Power of Iodine, &¢. for Electricity. 131

¥, any current that passed would be rendered evident by the
decomposition of the iodide of potassium.

» $. Iodine was fused in the tube G, and the end of its two
wires, I and H, were placed on the papers E and_F, as soon
as the iodine was solid; not the least spot of iodine was per-
ceived at E or H, though the battery employed consisted of
sixty pairs of plates, four inches square, in very strong action:
a small piece of wire was then made to connect I and H, just
where they are fused into the glass tube; and though they were
but momentarily connected, yet a dark spot of iodine was pro-
duced ; thus proving that the only interruption to the current
was that in the tube G, between the wires H and I.

Fig. 1.

D . EK

4. ‘The iodine was then replaced by a solution of iodine in
water; the current passed immediately, and produced its full
effect at A and H: the water only, however, was decomposed,
and no peculiar action was occasioned. But this is certainly no
proof that iodine is at all a conductor ; we very well know that
sulphuric acid added to water improves its conducting power,
and so do phosphoric and sulphurous* acids, and man
other acknowledged nonconductors; indeed, were it not for the
addition of certain nonconducting substances, such as sul-
phuric acid, the decomposition of water would hardly be ef-
fected by the voltaic battery. Again, M. De la Rivet has
remarked that bromine and chlorine are nonconductors, and

' * See Phil. Trans. 1834; Faraday’s Seventh Series, No. 755. for Lond.
and Edinb. Phil. Mag., vol. v. p. 257.—Enrr.)
« t Annales de Chimie et de Physique, 1827, vol. xxxv.

132 Mr. E. Solly on the Conducting Power of

that pure water is also one; but that a solution of bromine or
chlorine in water is a good conductor. A solution of iodine
in zther also allowed the transmission of electricity, but in a
less degree.

5. Iodine is soluble in carburet of sulphur, forming a fine
pinkish red solution; when boiled in it, a considerable quan-
tity is dissolved, which, upon cooling, is again deposited in
crystals: neither the hot nor the cold solution conducted the
electricity.

6. Iodine is also soluble in chloride of sulphur, forming a
deep red liquid; much more is taken up by boiling, and upon
cooling, crystals, probably of unaltered iodine, are precipitated.
Dr. Inglis says that “iodine and chloride of sulphur form a
compound, having many of the properties of bromine; but
that it is decomposed by galvanism, which the real bromine is
not.” The result of my experiments was different, for I found
that when the red liquid was submitted to the electric current
in G, it formed a perfect barrier to the passage of the elec-
tricity, and it is very certain that decomposition cannot be
effected without conduction. Perhaps Dr. Inglis will state
how the experiment was performed, and at which electrode the
jodine was evolved, or what were the substances evolved.

7. Bromine I found to be a nonconductor when placed in
the tube G; a solution of bromine in water was a much better
conductor than pure water, as M. De la Rive has mentioned
(see the above-quoted memoir). In these and all the follow-
ing experiments here described, the test of the wire (3.) was
applied.

s. A solution of bromine in ether conducts. AXther seems
to have a remarkable action on the colours of solutions con-
taining bromine, for whenever it is added to any of the deep
red solutions containing bromine, or the iodide of bromine,
the colour is rendered considerably lighter, so that an almost
opake solution becomes pale yellow, and quite transparent.

9. Bromine is soluble in chloride of sulphur, in the same
way as iodine, forming a beautiful red solution: this proved a
nonconductor; but upon adding a few drops of zther it be-
came aconductor. Bromine is also soluble in carburet of
sulphur, forming a splendid red solution, similar to the fore-
mentioned one: this was likewise a nonconductor; but a few
drops of zether rendered it a conductor.

10. Periodide of bromine was a conductor; the current
transmitted by it was fully able to decompose the iodide of po-
tassium at E and F; but thedecomposition of water, also placed
in the circuit, was effected with some difficulty. A little water
was now added to the periodide of bromine; the water floated
at the top, and dissolved a small portion of it: the water and the

Bromine, Iodine, and Chlorine for Electricity. 133

iodide of potassium indicated that the current was passing;
but the liquids in the tube G were not visibly affected.

11. An aqueous solution of the periodide of bromine being
put into the tube G, conducted, and was briskly decomposed ;
but both the platinum wires remained bright and clean, and
neither iodine, bromine, nor any compound of them, was
evolved or deposited on either electrode, though the action
was continued for some time.

12. A solution of the periodide of bromine was a good con-
ductor, and the current transmitted had sufficient intensity for
the electrolyzation of water. Solutions of the periodide, in
chloride of sulphur and carburet of sulphur, were nonconduc-
tors; upon the addition, however, of a few drops of zther, they
became good conductors.

13. The conducting power of chlorine was next tried, and
for this purpose the following apparatus was employed: A BC,

Fig. 2.

fig. 2, is a glass tube ;*,ths of an inch in diameter, having two
platinum wires fused into it at A, so as to be separated the 1,th
of an inch from each other ; the tube being then inverted, the
space from E to F was filled with peroxide of manganese and
muriatic acid; the end C was then carefully closed by a spirit
lamp, and the whole being cooled, it was placed in the posi-
tion represented in the figure, the space from E to C being
filled with a mixture for generating the chlorine, the other
parts of the tube having been carefully kept dry. Heat was
then applied to C, and B was immersed in ice-cold water; as
soon as a sufficient quantity of liquid had collected in B, A
was immersed in a mixture of ice and salt, and B was gently
warmed ; by this means the liquid chlorine was rectified, and
obtained quite free from water or other extraneous fluids at A.
Matters being thus arranged, and sufficient chlorine having
been condensed, the tube was placed in the same position as
the tube G in the former figure, one of the two platinum wires
resting on the moistened paper F, the other upon E, fig. 1.
I was at first surprised by finding it a conductor; but when
the tube was carefully wiped, so as to be quite free from all
adhering salt from the freezing mixture, it proved a perfect
nonconductor.

134 Mr. Sturgeon’s Description of the

14. The crystallized hydrate of chlorine was then put in the
tube G, fig. 1: it proved a nonconductor. A strong solution
of chlorine, placed in the same situation, was a good conductor.

From these experiments the following conclusions may be
drawn: Ist, that iodine, bromine, and chlorine are noncon-
ductors; 2ndly, that they improve the conducting power of
badly-conducting eiectrolytes; and 3rdly, that two noncon-
ductors combining can form a body which can conduct electri-
city, and which resists the decomposing power of the voltaic
battery.

7, Curzon Street, 15th January, 1836.

XXVI. Description of the Aurora Borealis of November
16, 1835. By W.Sturceon, Lecturer on Experimental
Philosophy at the Honourable East India Company's Military
Academy, &c. &c.*

N aurora borealis of a very unusual character was seen in
this neighbourhood, and I imagine over a large tract of
country, on Wednesday evening the 16th instant. I was
walking from Greenwich to Woolwich between nine and ten
o’clock; and when I had arrived at the top of Maize Hill, by
the side of Greenwich Park, then about ten minutes past
nine, my attention was first attracted by the fine light of the
aurora in the north. I walked on a little further till a good
opening to the northern horizon presented itself from the road
leading from Maize Hill to Mr. Angerstein’s estate. At this
opening I made a determined stand, for the purpose of observ-
ing any novel phznomenon which the aurora might happen
to present.

At this time it consisted principally of a very extensive la-
teral range, on both sides of the pole star, of vertical streamers,
which were pencilling thenorthern heavens from about 15°
above the horizon to Cassiopeia’s Chair, then about the meri-
dian; and so uniform was their arrangement and splendour
that they presented one sheet of yellowish white light, the
most intense at the base, and becoming more and more faint
as they proceeded upwards, until quite lost at their terminal
altitudes.

This appearance of the aurora had but just stamped its im-
pression on my mind, when in one moment the whole of the
northern heavens appeared in one complete state of undulat-
ing commotion, heaving upwards in rapid succession immense
waves of lightt, which, like the streamers which preceded

* Communicated by the Author.
+ These waves were seen at Milton next Gravesend by my scientific
friend Mr. Swinny ; and I beg to acknowledge the obligation I am placed

‘Aurora Borealis of November 16, 1835. 135

them, gradually diminished in brilliancy from their source near
the horizon till their arrival at the zenith, which was their ge-
neral vanishing point. ;

‘The horizontal range of the aurora during this unusual dis-
play was eastward as far as Jupiter, whose azimuth from the
north was then about 75°; and perhaps about the same ex-
tent westward on the other side of the pole star. 1 observed
it stretch to beyond @ Lyre (Vega), whose azimuth from the
north was about 60°, but could not very well ascertain the
position of the western extremity at the place where I was
standing, on account of the reflexion of the gas light in Lon-
don mixing with that of the aurora, and the intervention of
trees, &c.

This extensive ocean of light, which illuminated nearly half
of the visible heavens, and whose waves rolled with the rapidity
of thought, lasted about eight or ten minutes, perhaps longer,
when they gradually began to disappear, and the aurora to
contract in all its dimensions. Until this time (nearly half
past nine) no dense nucleus had marked the centre of the
aurora: the stars were seen between the horizon and the lu-
minous base as decidedly, though not so clear, as if no au-
rora were present. ‘The star Benetnasch, in the tip of the tail
of the Great Bear (y Ursae Majoris), was one of those which
were observed below the aurora; but Mizar (g Ursze Majoris),
then on the meridian below the pole, was seen in the bright
arched base of the streamers and waves.

The last-mentioned change in the appearance of the aurora
brougbt it gradually to that state which is usually exhibited
in some period or another of this boreal phenomenon. The
dense black nucleus began to form, and soon curtained the
stars which had previously twinkled in that segment of the
northern sky. The luminous margin also, its usual attendant,
became well defined, and its highest point was well marked to
the westward of the meridian, perhaps nearly in the magnetic
north. I now walked on, keeping the aurora in view, which
shot occasional streamers from various parts of the luminous
arch. Just before I entered Woolwich, about ten o’clock,
another fine display of vertical streamers spread over the
northern sky, and continued for nearly a quarter of an hour.
By this time I reached home; but too late to ascertain their
effect, if any, upon the magnetic needle, for they faded away
very rapidly after my arrival, and before eleven the aurora
had entirely disappeared.
under to Mrs. Swiony, who also saw these waves, for a more happy de-
scription of them than any I had before thought of. ‘They appeared to

this lady as “ waves of thin smoke or steam, behind which was placed a
strong light.” A more expressive description could not possibly be given.

136 Mr. J. Taylor on Rotatory Steam Engines. !

During my walk home, I observed several fine meteoric
stars, most of which appeared to be shot from the same point
of the heavens, which point was somewhere in a right line be-
tween me and the Twins. One of these meteors shot with a
moderate velocity across the north part of the meridian, at an
altitude of about 80°, and appeared to traverse an arch of the
heavens of 90° or 100°. It burst into several luminous frag-
ments at the western termination of its range, and became
extinct in a moment. I listened for some time, but heard no
noise; neither did my servant who was with me, and who
listened attentively at my request. I had previously point-
ed out to him the direction he was to look in, and he saw
the meteor from the first to its last appearance. He also di-
rectly afterwards saw another from the same quarter, which
traversed the heavens in nearly the same direction as the for-
mer. He called out to me, but it was lost without my seeing
+t. ‘These meteors were seen about five minutes before the
last display of streamers mentioned above.

I saw no appearance of the aurora to the south of the zenith,
though frequently looked for. The sky was quite clear of
clouds, and the black southern expanse, studded with its bril-
liant stars, afforded a fine contrast to the display of the aurora
in the north.

Artillery Place, Woolwich, Nov. 19, 1835.

N.B. Whilst writing the above, a friend has called on me,
who saw fine streamers about half-past eight o’clock.

De Ea

XXVIL. On the History of Rotatory Single Steam Engines
working expansively, in reply to Mr. Henwood. By John
Taylor, Esq. ERS., Treas. G.S.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
Me: HENWOOD by his letter in your last Number (p. 20.)
seems to exhibit a great desire for controversy, In as much
as he attacks me because my communication appears to him
to imply that a rotatory single engine working expansively is
something of novelty. Now, not to insist upon the thing be-
ing little known, it must be evident that it was no part of my
object to discuss whether the engine which I described was
new or otherwise, and that, in fact, I stated that it was not a
new invention, and mentioned another on the same construc-
tion formerly erected at Wheal Vor.
I have since found that Captain Francis of the Mold mines
has successfully applied the same principle to Whim engines;
and I am glad to hear that those of Messrs. Gregor and

Mr. J. Taylor on Rotatory Steam Engines. 137

Thomas seem further to prove that which I merely wished
to draw the attention of engineers to, and by making it public
in your pages, to give information which otherwise might not
for a long time to come have reached to other districts.

Having observed a certain instance of great improvement
in the ceconomy of fuel, applicable to that kind of engine which
is mostly employed in all the varied operations of our numer-
ous manufactures, I merely desired to communicate the know-
ledge of the fact; and, as I expressed in my letter, I pointed
it out as deserving attention and inquiry. I think it much
more important to the public to consider the steps by which
improvements are worked out to practical advantage than to
indulge in disputes about such originators of an invention as
did little more than to broach an idea, good enough, perhaps,
in itself, but which may only have been rendered valuable by
the superior skill or industry of others exerted in bringing it
into useful and general application.

This observation may apply to what Mr. Henwood chooses
to say of Mr. Woolf, respecting whom he seems to lose no
opportunity of endeavouring to detract from the merit to which
I and many others think he is entitled; my expression was
that we owe to him the method of working high-pressure
steam expansively *, and this is still my opinion. I have in
another place recorded Captain Trevithick’s engine at Wheal
Prosper, and so far have done him justice, but this engine
did only about 26 millions duty, and did not equal other en-
gines then working in the common way; nor does it appear
that Captain Trevithick followed up his invention or produced
any improvement upon the duty of the engines in Cornwall,
the average not having increased until two years afterwards,
when some of Mr. Woolf’s engines had attained to a duty of
50 millions, and Messrs. Jeffrey and Gribble had successfully
adapted the same principle to an engine with one cylinder.

Mr. Henwood in a note states correctly that Captain Lean
reports the duty of the Charles Town engine at 40 millions,
and not at 60, as stated by me. What, however, I did state
was, that when [I saw it, soon after it was put to work, it was
calculated to be performing a duty of about 60 millions. This
calculation was made by the principal agent of the mine, and
the engineer on the spot, and I saw no reason to doubt their
accuracy, and gave their account as I received it, adding, how-.
ever, that I had desired that its performance should be re-
gularly reported in the monthly duty papers, by which of
course any error in this respect would certainly be set right ;

{* Our much respected predecessor, Dr, Tilloch, expended a consider-
able part of his property in his zeal for assisting Mr. Woolf.—Ebrr.}

Third Series. Vol. 8. No. 45. Feb. 1836. Q

188 Mr. Woodward’s Reply to Mr. Charlesworth.

and observing that, if the rate of duty which I had mentioned
could be maintained, a very great improvement might take
place in the engines most generally employed.

I still think that this is a very important object for the con-
sideration of persons who employ or construct steam engines ;
and if Mr. Henwood’s notice of my short letter should assist
in interesting them in the subject, it will not be without its use,
though I may not be inclined to trouble you again upon the
disputed points. I am, Gentlemen, yours very truly,

Bedford Row, Jan, 26, 1836. Joun Taytor.

XXVIII. Cn the Crag Formation; in answer to Mr. Charles-
worth’s “ Reply.” By Samuet Woopwarp, Esq.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
HE severe animadversions by Mr. Charlesworth, in your
Number for December 1835, on my notice of his former
paper, necessitates my requesting the favour of your inserting
a few lines in reply.

Mr.Charlesworth’s remarks about “breach of decorum” and
‘*impugning his veracity,” &c. &c. [ leave to the good sense
of your readers; neither do I intend to quarrel about words.
The difference between my opponent and myself appears to
be this: He makes his “ red crag” a distinct formation, newer
than the one upon which it reposes. I, on the contrary, have
asserted it to be diluvial or disrupted crag, and cited as ex-
amples the cliffs north and south of Yarmouth and at Cromer.
Mr. R. C. Taylor, at p. 21 of his Geology of Eastern Norfolk,
states, that “‘ the crag itself has, at the last of the geological
epochs, been subject to abrasion by the diluvial currents to
which allusion has been made. Their fragments, mingled
with those of the chalk and preceding formations, piled in
enormous heaps, form the cliffs of Cromer and Trimmingham,
Z50 or 300 feet in thickness, upon the original crag, which
rests, 22 situ, at their base.” And, strange to say, at p. 86,
Mr. Charlesworth, forgetting his discovery that “ the red crag
was a gradual deposit formed by successive accumulations of
marine exuvie,” quotes my friend Mr. Searles Wood as fol-
lows: ‘ Jam inclined to think the whole of the upper stratum
has been produced from the ruin of the lower.” After such
a contradiction of himself I might surely with greater pro-
priety retort upon him the passage occurring at p. 466, |. 27.

My impression on the first glance at the upper bed at
Ramsholt was, (comparing it with the Norfolk deposit,) that,
from its discoloration by the oxide of iron and there being no

—

Reviews, and Notices respecting New Books. 139

superincumbent bed except vegetable mould, it must belong to
the diluvium ; and on examination I could find no perfect shells;
all appeared to me to be waterworn and broken into fragments,
and to have been transported from some other deposit.

I have shown Mr. Charlesworth the note I made at the
time on the lower bed, which is as follows: ** From the or-
ganic remains resembling those of Malta, figured by Scilla,
in his Corporibus Marinis, &c., 1 am inclined to think the
sheils of this bed much newer than those reposing on them.”
This opinion has unexpectedly been confirmed (contrary to
Mr. Charlesworth’s conjecture at p. 92,) by the latest infor-
mation from M. Deshayes, communicated to Mr. Lyell; by
which it appears that a larger percentage of recent species
has been detected in the so-called “coralline crag” than
from perhaps any other portion of the great deposit. If such
is the fact, and I have no reason to doubt my authority, there
is an end of the question between my opponent and myself.

The propriety or impropriety of calling the lower bed
“coralline crag” is, I conceive, of little moment, and a mere
question of words, and not of facts. What I contended for
was, that it was not composed of corallines [corals] as that
at Aldborough; and my opinion still is, that the use of the
term, as distinguishing the epoch of any portion of the crag,
tends only to mislead the inquirer.

Iam, Gentlemen, yours, &c.
Lakenham Grove Cottage, SamMuEL Woopwarp.
Norwich, Dec. 4, 1835.

XXXI. Reviews, and Notices respecting New Books.

Newton and Flamsteed, Remarks on an Article in Number CIX. of
the Quarterly Review: by the Rev. Witt1AM WueEweE Lt, M.A.,
Fellow and Tutor of Trinity College, Cambridge. Deighton,
Cambridge; and Parker, Strand.

HE attention of the public has been lately directed with anxious

interest to the character of Sir Isaac Newton, by an article in
the Quarterly Review, founded upon Mr. Baily’s Account of Flam-
steed, prefixed to an edition of his Observations, printed by the Board
of Admiralty ; and copious extracts from this ‘ Account’ have been
given by some of our contemporaries.

The work itself not being published, but privately distributed, we
have had no opportunity of judging for ourselves as to the value of
the conclusions drawn from the letters of Flamsteed, and the grounds
which they afford the Reviewer for announcing to the world, though
with professions of regret, that the name of Newton is nolonger to he
hadinreverence. From the appearance, however, of Mr. Whewell’s
short pamphlet entitled ‘Newton and Flamsteed,’ we have now
the satisfaction of finding that the subject has been fully investigated

Qe

140 Reviews, and Notices respecting New Books.

by one who will be universally considered as most competent to
form a correct judgement :—and to very many who have beendwell-
ing with grief and wonder upon the painful impressions created by
this Review of an unpublished book, the following decisive expres-
sion of Mr. Whewell’s opinion will be very grateful :

‘I shall conclude; leaving it to the reader to decide—whether
the blame of intemperate virulence of feeling and irrational violence
of conduct does not rest solely with Flamsteed ;—whether Newton’s
philosophical and moral character do not come out from this exa-
mination BLAMELESS and ADMIRABLE, as they have always been
esteemed by thinking men;—and whether the Reviewer has not
shown extraordinary ignorance of that part of scientific history
which he has pretended to elucidate, and unaccountable blindness
and perverseness in his use even of the ex parte evidence which
he had before him.”

Mr. Whewell’s pamphlet evinces the clear-sightedness and candour
for which he is distinguished, Though a very short, itis a very ad-
mirable and interesting production, and entitles its author to rank
as high for moral discrimination, as he does for scientific attain-
ments. We shall take the liberty to quote rather largely, knowing
the interest which must be taken in the subject. With regard to
the Reviewer's unaccountable blindness, perverseness, and partiality,
he justly remarks, that “‘ he has taken for his sole guide the state.
ments of one of the parties, written in the warmth of the moment,
—has identified himself with Flamsteed’s most petulant feelings, and
has not corrected them by any attention to the case of the opposite
party. Whenthe great body of Review Readers are called upon, in
this temper, to cast away all their reverence * for the most revered
name of our nation, it must be right that some one should interpose
a warning, and deprecate judgments of such levity and partiality.”

“It is to be observed,” adds Mr. Whewell, “ that if we adopt the
Reviewer's opinion, that Flamsteed was throughout a man bitterly
wronged, and that there was an extreme of baseness and tyranny
on the side of the persons with whom he quarrelled, we involve in
our condemnation almost all the eminent literary and scientific men
of the day +: for we have, acting with Newton, and sharing in his
views, not only Halley, the object of Flamsteed’s intense dislike, but
Gregory, Arbuthnot, Mead, Sloane, Wren.

« The purpose for which Newton desired that the world should
pessess the best observations, was the confirmation of the great
Theory of Universal Gravitation ;—incomparably the greatest dis-
covery ever made by man; and at that period, we may say, in the
agony of that latent struggle by which the confirmation and general
reception of great discoveries is always accompanied. We of the
present day are accustomed to consider this immense step as effected
at once, on the publication of the first edition of the Principia in
1687 ; but we may easily convince ourselves that this was not so.
Even under the most favourable circumstances, a vast theory like

* The Edinburgh Review intimates that this reverence has been all a
mistake, attributable to one Mr. Conduit!

+ Designated by the Edinburgh Reviewer as ‘ Newton's party”: vide
infra, p. 144.

“ Newton and Flamsteed,”’ by the Rev. W. Whewell. 141

this could not make its way at once. No man of Newton’s standing
(I believe) thoroughly accepted his views: Halley was sixteen, David
Gregory nineteen years his junior. In England this acceptance of
the theory required half a generation, in France and Germany
more than a whole generation. And during this interval, the re-
sult of the struggle depended upon the accordance of the theory
with the best observations, which the Greenwich ones undoubtedly
were. Upon these observations, then, depended a greater stake in
the fortune of science than was ever before at hazard, and this New-
ton knew well. How then can one be surprised at the earnestness
and importunity with which he begs for Flamsteed’s observations ;
and tries to soothe a jealousy and reserve which appear to have
shown themselves at an early period?

“As for your observations, you know I cannot communicate them to
any body, and much less publish them, without your consent. But if 1
should perfect the moon’s theory, and you should think fit to give me leave
to publish your observations with it, you may rest assured that I should make
a faithful and honourable acknowledgment of their author, with a just cha-
racter of their exactness above any others yet extant. Inthe former edition
of my book, you may remember that you communicated some things to me,
and I hope the acknowledgments I made of your communications were to
your satisfaction: and you may be assured I shall not be less just to you for
the future. For all the world knows that I make no observations myself,
and therefore I must of necessity acknowledge their author: and if I do not
make a handsome acknowledgment, they will reckon me an ungrateful
clown.— Account of Flamsteed, p. 151.

«« This the Reviewer has quoted ; but he has not quoted what
immediately follows, striking as it is.

“And, for my part, I am of opinion that for your observations to come
abroad thus with a theory which you ushered into the world, and which by
their means has been made exact, would be much more * for their advantage
and your reputation, than to keep them private til] you die or publish them,
without such a theory to recommend them. For such theory will be a de-
monstration of their exactness, and make you readily acknowledged the ex-
actest observer that has hitherto appeared in the world. But if you publish
them without such a theory to recommend them, they will only be thrown
into the heap of the observations of former astronomers, till somebody shall
arise that, by perfecting the theory of the moon, shall discover your obser-
vations to be exacter than the rest. But when that shall be, God knows: I
fear, not in your life-time, if I should die before it is done. For I find this
theory so very intricate, and the theory of gravity so necessary to it, that I
am satisfied it will never be perfected but by SomzBopy WHO UNDERSTANDS
THE THEORY OF GRAVITY AS WELL OR BETTER THAN I po,—p. 151-152.

“<I have several times,” observes Mr. Whewell, “in reading this
passage, felt a kind of terror at the peril to which the success, or
at least the speedy success, of the greatest of physical truths is here
represented as exposed.” He justly adds,

«« With this consciousness of being in possession of such a truth,
while Flamsteed’s records of his observations contained the only
language in which it could be made generally convincing, we ma
easily imagine that Newton could not help urging the publication
and employment of the observations, in a manner which excited no

* Erroneously printed “worse ” in the work.

142 Reviews, and Notices respecting New Books.

sympathy in Flamsteed, unconscious of the nature of the then ex-
isting crisis in the history of astronomy.

*«« Flamsteed was only four years younger than Newton; he never
fully accepted Newton's theory, nor comprehended its nature. Like
all astronomers of his time, he understood by ‘ theory’ only a mode
of expressing laws of phenomena, not a new generalization by which
such laws are referred to a physical cause.” Thus, having been told
that Newton had deduced all the inequalities of the moon’s motion
from the laws of gravity alone, he says, in a letter to Lowthorp,

“ With some indignation I answered that he had been as many years upon
this thing, as I had been on the constellations and planets altogether:.....that
I had imparted above 200 of the moon’s observed places to him, which one
would think should be sufficient to limit any theory by; and since he has
altered and suited his theory till it fitted these observations, ’tis no wonder
that it represents them: but still he is more beholden to them for it than
he is to his speculations about gravity, which had misled him.

«He appears,” adds Mr. Whewell, « to have thought too directly
of the value of his observations, as the means of purchasing reputation.
How otherwise are we to account for the jealousy with which he
objected to Newton’s combining Cassini’s observations of the comet
of 1680 with his? when it must have been clear, even with his own
notion of a theory, that the truth of the theory would be the better
established, the more observations it agreed with. This is Flam-
steed’s own account of an interview with Newton in the letter just
quoted :

“Some occasion of discourse about comets happening, I acquainted him
that Dr. Gregory gave out that since he had altered his paths of comets, and
instead of parabolas made them ellipses, his theories would represent all
Mons. Cassini’s observations within a minute, whereas I thought he had
only my observed places to represent, and that it was not only an injury ¢o
me, but the nation, to rob our Observatory of what was due to it, and further
to bestow it on the Hrench.—p. 174.

As the accusations against Newton are, as Mr. Whewell justly
observes, wholly ex parte, so it is evident how narrow were the views
and how wretched the temper of his detractor. Mr. Whewell cha-
yacterizes Flamsteed as having been ‘“‘ of weak temper, suspicious,
irritable, and self-tormenting. We can hardly think otherwise of a
man who was in the habit of brooding over the movements of spleen
excited by casual expressions in the letters of his correspondents,
and recording them in ink on the paper. Thus, as early as 1694,
Newton happens to write to him (p. 139), «I believe you have a
wrong notion of my method in determining the moon’s motions’;
on which Flamsteed makes this note, ‘I had: and he of me: and
still has. And after this period almost every letter of Newton’s has
a similar comment appended to it, and these become more and more
bitter. Yet Newton appears to have been his friend as long as Flam-
steed’s temper allowed him to beso. A little after the above letter

he writes :

“ What you say about my having a mean opinion of you is a great mis-
take. I have defended you where there has been occasion, but never gave
way to any insinuations against you. And what I wrote to you, proceeded
only from hence, that you seemed /o suspect me of an ungrateful reservedness,
which made me begin to be uneasy,” —p. 146.

** Newton and Flamsteed,” by the Rev. W. Whewell. 143

“ Surely there is no want of kindly feeling in these expres-
ees. FF).

«« The wrathful temper of Flamsteed’s dealings with Newton and
his friends is indeed so manifest, that it is quite marvellous the ne-
cessity of making allowance for it should not have occurred to the
Reviewer. Who, for example, can overlook it in the account which
Flamsteed has given in his own Diary of his appearance before the
Committee of the Royal Society on Oct. 19, 1711, and which the
Reviewer has quoted at length? This Committee, it is to be ob-
served, were the guardians of the national interest in the Greenwich
observations, and were bound to see that Flamsteed made them ac-
cessible and useful to the public. According to his own account
he began by calling them ‘ the robbers of his property.’ In describing
the altercation which ensued, he says, ‘I only desired him (Newton)
to keep his temper, restrain his passion, and thanked him as often
as he gave me ill names.’ And again, in another part of the con-
versation: ‘I only desired him (as | had often done) to restrain his
passion, keep his temper, &c.’ We hardly require the recollection
of Sir Anthony Absolute to see here the demeanour of a very angry
man; far too angry, certainly, to allow us to accept literally what
he asserts, much less what he implies merely. I confess therefore I
have great doubts whether, from the expression in the same account,
‘he called me many hard names, puppy was the most innocent of
them ;’ (p. 228.) we can confidently infer that the obnoxious term
was used.”

Perhaps we should express more exactly the impression conveyed
by Flamsteed’s passionate and wrong-headed statements, if we were
to say, that the term ‘puppy’ may very possibly have been in some
way or other used by Newton (certainly Flamsteed’s self-compla-
cency and self-will made it far from inapplicable), but that, if so, it
is certain that it was the most and not the least angry word which
was thus employed. If anything worse had been said, it is very clear
that Flamsteed was not in a temper to omit recording it in his letters
and journal.

With regard to the accusation, of which it is attempted to make
so much, respecting the packet containing that part of Flamsteed’s
Catalogue which had, after much prevarication and many ex-
cuses, been obtained from him, and placed in Newton’s hands sealed
up, Mr. Whewell observes, p. 16, “‘that the case is very different
from that which the Reviewer has collected, by confining himself to,
and, what is more extraordinary, by adopting without modification,
the indignant and querulous account given by Flamsteed. * *

“ It must be recollected that any assumption on the part of Flam-
steed, that he might deal with the observations made in his official
capacity of Astronomer Royal, as if they were his private property,
could not be allowed by the guardians of the institution ;—that New~
ton and the persons who acted with him, acted not as private persons,
nor at the suggestion of their own caprice, but took measures for the
publication, as the Visitors of the Observatory, bound by their duty
to see the office made effective ;—that the sealed packet being thus

national property, the seal was declared to have been broken by the
Queen’s command,”—p. 16.

144 Reviews, and Notices respecting New Books.

We may remark, that it seems impossible to assign any meaning
to the deposit of the sealed packet but that, 2f necessary, it was to
be opened. The necessity did occur, for Flamsteed refused to go
on with the printing. If the work had been allowed to be finally
stopt, of what use was the packet ?

«« Newton was acting as the authoritative head of a national body,
and had, in that capacity, to repress, what must have appeared to
him, extravagant claims and offensive behaviour.”—p. 13.

«« Almost thirty years had elapsed during which Flamsteed pos-
sessed the title of Astronomer Royal, and nothing had proceeded
from the magnificent Observatory with which he was entrusted.” —
Halley's Preface.

In further illustration of the intellectual and moral character of
Flamsteed, we add the following from Number cxxvz. of the Edin-
burgh Review, just published, in which we do not find any mention of
Mr. Whewell’s Remarks :

“If we consider the vast progress that was made in astronomy
from the time of Tycho, or rather Hevelius, to Bradly, and the nu-
merous inventions and discoveries by which every branch of it was
enriched, we can scarcely find one, either inrespect of theory, or of
instruments, or of methods of observation or computation, to which
he [Flamsteed] can justly lay claim. Delambre, indeed, allows him
the merit of having been the first who practised the method of de-
termining the place of the equinoxes from observed equal declina-
tions of the sun; but if we except this, which, moreover, was an
easy corollary from Picard’s then well-known method of determining
the time from observations of equal altitudes, zt would be difficult to
show that he made a single step in advance of his age. The cha-
racter of his mind is more remarkable for activity, and that sort of
sagacity which leads to practical skill, than for any of the higher
endowments. In point of genius, his name is not to be mentioned
with that of Newton ; he was immeasurably inferior even to his rival,
Halley. His mathematical knowledge, even for the time, appears
to have been extremely limited. He set no value on the physical
speculations of Newton, and evidently never understood them. He
sneers at his ‘ conceptions’ about gravity, calls him ‘ our great pre-
tender,’ carps at the lunar theory, does not ‘ relish the small equa-
tions,’ and determines ‘to lay these crotchets of Newton aside.’ On
no occasion does he attempt to establish a principle, or refer a phe-
nomenon to gravitation ; and he left to one of his successors the two
most brilliant discoveries of modern astronomy, the aberration and
nutation, though both were within his reach. In fact, he himself
clearly pointed out the effect of the former, and even defined its
amount ; but he mistook (in common, however, with others) the
phenomenon for the effect of parallax, although the simplest mathe-
matical considerations might have shown him that parallax would be
manifested in quite a different manner. Newton suggested to him
the importance of noticing the state of the barometer and thermo-
meter at the time of the observations, but he neglected the good
advice. Even in respect of instrumental accuracy he perhaps came
rather behind than preceded the attainments of his day.”"—p. 369.

“On the recommendation of Newton and Arbuthnot, a royal

*© Newton and Flamsteed,” by the Rev. W. Whewell. 145

warrant was obtained from the Queen, in December, 1710, consti-
tuting the President (Newton) of the Royal Society, and whoever
else the Council should think fit, Visttors of the Observatory ; au-
thorizing them to demand of the Astronomer, ‘ within six months
after the year shall have expired,’ a copy of the annual observations,
to direct such observations to be made as they should think fit, and
to inspect the instruments, and report on their state to the Board
of Ordnance. Flamsteed, who saw clearly that he would now be
placed more at the mercy of Newton’s party * than ever, complains
loudly of this measure—insinuates that nobody knew his business
but himself—and tells us he was worse used than the ‘ noble Tycho,
who had no visitors of his observatory appointed over him.’

“«« He also remonstrated against the appointment to the Secretary
of State (St. John), but was ‘ answered haughtily, the Queen would
be obeyed.’ He even drew up a petition to the Queen, in one of
the clauses of which he prays,

««That I maynot have the President of the Royal Society, nor any of their
Council, set over me as visitors, nor suffered to prescribe to me what obser-
vations to make, since they know little of my business, and will but incom-
mode me in my progress, and obstruct me; as some of them have done for-
merly ; but that such of the nobility or gentry that are skilful in mathematics,
together with the principal officers of your Majesty’s Ordnance, that have been
founders of my studies, may have the inspection and care of the Observatory.’

“ The idea of seeking among the nobility and gentry for visitors
who should know more of his business than Newton and Halley,
with the Council of the Royal Society, may be allowed to be origi-
nal; but we suspect the qualification on which Flamsteed would
have set most value, would have been a disposition to allow him to
manage his business in his own way. At all events he seems to
have had no very high opinion of the Royal Society, of which he
thus writes ina letter to Sharp: ‘ Our Society decays, and produces
nothing remarkable, nor is like to do it, I fear, while ’t is governed
by persons that either value nothing but their own interests, or un-
derstand little but vegetables, and how, by making a bouncing noise,
to cover their own ignorance.’ ”—p. 383.

Halley, however, the Edinb. Reviewer adds, “ was better ac
quainted with llamsteed’s business, that is, with practical astrono-
my, than any other individual ; and hence Flamsteed’s anxiety, of
which some amusing instances occur, to keep him in ignorance of
what he was doing.

** Flamsteed, as our extracts have made evident, entertained a
most exalted opinion of his own importance, and the superiority of
his knowledge of astronomy, Halley commenced his scientific ca-
reer as an astronomer, and by making a catalogue of stars; and
therefore from the first was placed in a situation of direct rivalry
with him. He had likewise acquired, by the versatility of his pur-
suits and employments, a large share of popular fame, of which
Flamsteed appears to have been not a little envious.”—p. 393.

The Quarterly asserts that Halley was “ low and loose in his con-
duct, andashameless infidel.” On this subject the Edinburgh says :

{* These are unfair expressions of the Reviewer, calculated to create a
prejudice.—Eprr. |

Third Series. Vol. 8. No. 45. Feb, 1836. R

146 Reviews, and Notices respecting New Books.

« Tt has been surmised that Flamsteed’s aversion to Halley arose
from the libertine conduct and infidel opinions* which the latter en-
tertained, and took no pains to conceal. We have no evidence of this.”

«« Flamsteed’s charges are exaggerated to a degree that at the
present time makes them appear almost ludicrous.’’—Edinb. Rev.
exxvi. p. 363.

To this more might be added from the records of the time in proof
of Flamsteed’s bad disposition and disingénuousnesst, of which what is
called his piety cannot be received as an extenuation, as it appears
to have consisted in claiming the Deity as his partisan in all his
quarrels. Nor can his belief in judicial astrology be lost sight of,
nor his journey to Ireland to be touched for the benefit of his dis-
eased body by a gentleman, ‘‘ whose gift,” he tells us, ** was of God.”

How great is our astonishment, then, to find the Edinburgh Re-
viewer, after giving such a low estimate of Flamsteed’s character,
so inconsistent, or so far mystified by the ‘leperous distilment ° of
the Quarterly, as to call on us to credit the uncorroborated assertions
of such a person, in opposition to the uniform testimony of Newton's
distinguished contemporaries! During a very long life, no man ever
was more the object of general interest and of close observation. If
the letters of ill-conditioned persons are brought to light, what can
we expect to find in them but complaints and calumnies? The
Quarterly tells us for our consolation, that if we have lost a New-
ton, we have, forsooth, gained a Flamstezd! The Edinburgh goes
so far as to favour us with an hypothesis to account for the origin
of the mistaken opinion which has hitherto prevailed that Newton
was a man of great moral worth! namely, that all the traditions of
his moral character are derived from no other source than the Eloge
of Fontenelle, who had his information solely from Mr. Conduit, a
relation of Newton, and the inheritor of his property ! Can anything
be more ludicrous ?

We shall conclude with citing the character which is given of
Mr. Whewell by another writer in the same Number of the Edin-
burgh Review.

«« Mr. Whewell has already, by his writings, approved to the world,
not only his extensive acquirements in mathematical and physical
science, but his talent as a vigorous and independent thinker. To
a narrower circle, he is known as the principal public tutor of the
principal college of his University; and in this relation, his zeal, and
knowledge, and ability have concurred in raising him to an enviable
eminence. Though more peculiarly distinguished by his publications
in that department of science so exclusively patronized by the Uni-
versity, he has yet shown at once his intelligence and liberality, by
amplifying the former circle of studies pursued in the college under
his direction; and, in particular, we are informed that he has ex-
erted his influence in awakening a new spirit for the cultivation of

* Tt appears that Newton sometimes gravely and kindly expostulated with

Halley upon the latter subject: Flamsteed reviled him, and calumniated his
moral character.

+ See his conduct with regard to Hooke, in the Royal Society, Nov. 2,
1681, and Feb. 15, 1682, when he attempted to escape the disgrace due to
his confident ignorance by a low fraud.

6

Royal Society. 147

mental philosophy ; in which department hehas already introduced,
or is in the course of introducing, a series of more appropriate au-
thors than those previously in use.”—Review of Whewell’s Thoughts
on the Study of Mathematics as a part of a Liberal Education, p.410.

We rejoice that such a man has stept forward to dissipate our an-
xieties, and to disabuse the public ; and do not hesitate to rely on the
assurance of so competent a judge, and one who has had opportuni-
ties of carefully examining the subject, that © Newton’s philosophical
and moral character come out from this examination blameless and
admirable, as they have always been esteemed by thinking men.”

XXX. Proceedings of Learned Societies.

ROYAL SOCIETY.
[Continued from vol. vii. p 412.)

Nov 19, “ OX the Empirical Laws of the Tides in the Port of Liver-
1835.— pool.” By the Rev. William Whewell, M.A., F.R.S.

The author employs the results of the discussion of sixteen years of
tide observations made at Liverpool, published by Mr. Lubbock in the
Philosophical Transactions for the present year, in testing and im-
proving the formule, expressing the mathematical laws of the inequa-
lities of the phenomena of the tides, which had already been deduced
by the author from the London tide observations. He finds that the
Liverpool observations have not only confirmed, in the most satisfac-
tory manner, these formule, but have furnished the means of greatly
improving them. The corrections for lunar parallax and declination,
which, as far as they depended on the former investigation, might be,
considered as in some measure doubtful, and only locally applicable,
have now been fully verified as to their general form ; the nature of
the local differences in the constants of the formulz has also, in part,
come into view ; and the investigation has, moreover, shown that,
notwithstanding the great irregularities to which the tides are subject,
the results of the means of large masses of good observations agree
with the formule with a precision not far beluw that of other astrono-
mical phenomena. ‘The formule obtained point directly to a very
simple theory of the circumstances of tides, namely, that the tide at
any place occurs in the same way as if the ocean assumed the form
of equilibrium, corresponding to a certain antecedent time, and differ-
ent place. The ocean, in its position of equilibrium, would have the
form of a spheroid, of which the pole would revolve round the earth,
following the mvon at a certain distance of terrestrial longitude. This
distance is termed by the author the retroposition of the theoretical
tide in longitude, its mean value being what he has termed in other
communications, the corrected establishment of the place. If from an
original equilibrium tide, a derivative tide were sent off, along any chan-
nel, in which it is no Jonger infiuenced by the forces of the moon and
sun, it would take a certain time in reaching any place in that chan-
nel, and the circumstances of the tide at that place would not depend
on the positions and distances of the moon and sun at the time when
the tide happens, but on the positions and distances of those lumina-
ries at a certain time, anterior to the time of the tide, by the interval
occupied in the transmission of the tide along the channel. This inter-

R 2

148 Royal Society.

val of time, which, in his fermer papers, the author had called the age
of the tide, he here terms the retroposition of the theoretical tide in time.

Adopting this phraseology, the author finds that the phenomena of
the Liverpool tides may be expressed as follows.

1. The effects which the changes of the moon’s force produce on
the tides are the same as the effects which those changes would pro-
duce upon a retroposited equilibrium tide.

2. The retroposition of the tide in longitude is affected by small
changes, which changes are proportional to the variations in the moon’s
force.

3. The retroposition of the tide in time is also affected by small
changes, which changes depend on the variations in the moon’s force.

On the hypothesis that an equilibrium tide give rise to the Liver-
pool tides, we must suppose that the channel by which they are trans-
mitted occupies in length, from west to east, 11" 6™ of longitude; or
we may suppose the tide spheroid to lie behind the position of equi-
librium by a certain space; and the longitude occupied by the chan-
nel from end to end, may be supposed to make up the rest of the 115
6™, the retroposition of the tide in longitude. The author proceeds
to show how the circumstances of the tide may be hypothetically re-
presented on these suppositions; although it is not to be imagined
that these hypotheses are strictly accordant with the true state of the
case. As the general laws of the tides at other places must resemble
those at Liverpool, they will of course be capable of being represented
in a similar manner.

The remainder of the paper is occupied by a comparison of the data
of observations at London and Liverpool, and by an investigation of
the corrections in the formule thence resulting.

November 26, 1835.—‘‘ Observations on Halley's Comet, made at
Mackree, Sligo, in the Months of August, September, October and
November 1835.” By Edward J. Cooper, Esq. Communicated by
Capt. Beaufort, R.N., F.R.S.

These observations are communicated in the state in which they
were taken, and without the corrections for refraction and parallax,
with a view to assist computers in the calculation of a new approxi-
mate orbit. They were made principally with the author’s equatorial
telescope, having a focal length of 25 feet 3 inches, and a clear aper-
ture of 13°3 inches. Some few, however, were taken with the finder,
which is 6 feet 6 inches in focal length, and 4-9 inches clear aperture.
The eye-pieces used were, one by Frauenhofer (an illuminated wire-
micrometer), one by Messrs. Troughton and Simms (an illuminated
field-micrometer), a comet eye-piece, and the ordinary eye-piece of
the finder. The first of these had a magnifying power of about 400,
the second of 226, the third of about 95, and the fourth about 40.

«An Account of the great Earthquake experienced in Chili, on the
20thof February 1835,” withaMap. By Alex. Caldcleugh, Esq., F.R.S.

An idea formerly prevailed among the inhabitants of Chili, that the
earthquakes of those regions take place at certain regular periods ;
but it is now sufficiently proved, from the numerous catastrophes of
this kind which have occurred during the present century, that they
may happen indiscriminately at all times, and in all states of the at-

Royal Society. : 149

mosphere. The author is disposed to place but little reliance on most
of the supposed prognostics of these convulsions: but he mentions
that, previously to the earthquake described in the present paper, there
were seen immense flocks of sea birds, proceeding from the cuast to-
wards the Cordillera, and that a similar migration had been noticed
prior to the great shock of 1822. From his own observations, he con-
cludes that the barometer usually falls shortly before any considerable
shock, and that it afterwards rises to its ordinary mean height. Both
before, and also at the time of the convulsion, the volcanos of the
whole range of the Cordillera were observed to bein a state of extra-
ordinary activity.

The earthquake began at half-past eleven o’clock in the morning
of the 20th of February. The first oscillations of the earth were gen-
tle, and attended with little noise : they were succeeded by two ex-
tremely violent tremors, continuing for two minutes and a half, the
principal direction of the motion being from south-west to north-east ;
and they were attended by aloud report, apparently proceeding from
the explosions of a volcano to the southward. All the buildings of
the town of Conception were thrown down during these undulations.
At the expiration of half an hour, when the inhabitants, who, on the
first alarm, had fled to the neighbouring heights, were preparing to
return to their houses, it was observed that the sea had retreated to
such a distance that the ships in the harbour were left dry, and all
the rocks and shoals in the bay were exposed to view. At this pe-
riod an immense wave was seen slowly advancing towards the shore,
and, rolling majestically onwards, in ten minutes reached the city of
Conception, which was soon overwhelmed in a fiood of an altitude of
28 feet above high-water mark. The few persons who had remained
in the town had but just time to make their escape, and to behold from
the rising grounds, the complete submersion of the city. All objects
that were movable were swept away into the ocean by the reflux of
this great wave, which was succeeded by several similar, but smaller
waves, completing the work of destruction, and leaving behind them,
on their final retreat, a scene of universal havoc and desolation.

The island of Santa Maria, which is situate to the southward of the
bay of Conception, and is about seven miles broad, and two long, re-
mained, after the earthquake, permanently elevated at least ten feet
above its former position; anda similar change was found to have
taken place with regard to the bottom of the sea immediately sur-
rounding the island. The amount of this elevation was very accurately
ascertained by the observations of Capt. Fitzroy, who had, previous]
to the earthquake, made a careful survey of the shores of that island ;
thus supplying the most satisfactory and authentic testimony to this
important fact.

‘The author gives, in the course of the paper, several particulars re-
lating to the effects of the earthquake in different parts of the Chilian
coast; the oscillations appearing to have extended to the north as far
as Coquimbo, and to the east as far as Mendoza, at the ridge of the
great chain of the Andes. Vessels navigating the Pacific Ocean,
within a hundred miles of the coast, experienced the shock with con-
siderable force. Its influence was very perceptible in the island of

150 Royal Society: Anniversary Proceedings for 1835.

Juan Fernandez, a basaltic mass 360 miles distant from the coast ; as
was shown by the sudden elevation and subsidence of the sea, which
at one time rose 15 feet above the usual level, carrying all before it.

Anniversary Meeting, Nov. 30th, 1835.—John William Lubbock,
Esq. V.P. and Treasurer, in the Chair.

After the transaction of certain formal business the Secretary
read the Report, from which the following are extracts :

“The Council have to report the following statement of their pro-
ceedings during the past year, as far as they relate to matters of ge-
neral interest to the Society.

*“« By an arrangement made with the Trustees of the British Mu-

seum, a sum of 165/. has been placed at the disposal of the Library —

Committee for the purchase of books, in consideration of a grant by
the Society to the British Museum of fifty-five volumes of Oriental
Manuscripts.

“The printing of the classed Catalogue, under the direction of
Mr. Panizzi, is in great forwardness, and will soon be completed.

“The Council have the satisfaction of reporting, that the Com-
mittee appointed, in compliance with the wishes of the Lords Com-
missioners of His Majesty’s ‘Treasury, and of the Honourable Board
of Excise, for the purpose of giving their opinion on the construction
of instruments and tables for ascertaining the strength of spirits, in
reference to the charge of duty thereon, have nearly completed their
labours, and will very shortly be ready with their Report.

“The Copley Medal for the present year has been awarded to
William Snow Harris, Esq., for his ‘ Experimental Investigations of
the Forces of Electricity of high Intensity,’ contained in his paper
published in the Philosophical Transactions for the year 1834
(p. 213; Proceedings, p. 277. No. 16.)

«One of the Royal Medals for the present year has been awarded
to Michael Faraday, Esq., for his investigations and discoveries con-
tained in the series of ‘ Experimental Researches in Electricity,’ pub-
lished in the Philosophical Transactions, and more particularly for the
Seventh Series, relating to the definite nature of Electro-chemical Ac-
tion. (Phil. Trans. for 1834, p. 77; and Proceedings, p. 261, No. 15.)

«The other Royal Medal for the present year has been awarded
to Sir William Rowan Hamilton, Andrews Professor of Astronomy
in the University of Dublin, for the papers published by him in the
16th and 17th volumes of the Transactions of the Royal Irish Aca-
demy, entitled ‘ Supplement to an Essay on the Theory of Systems
of Rays,’ and more particularly for those investigations at the con-
clusion of the third and last Supplement, whick relate to the disco-
very of Conical Refraction.

“The Council propose, in the year 1838, to give one of the Royal
Medals to the most important unpublished paper on Chemistry, and
the other Medal to the most important unpublished paper on Mathe-
matics, which shall have been communicated to the Royal Society
for publication in its Transactions, after the present date and prior
to the month of June 1838.

The Secretary also read the following List of Fellows deceased
since the last Anniversary : viz.

On the Home List.—His Royal Highness the Duke of Gloucester ;

Royal Society. 151

Sir William Blizard, Knt.; Sir David Barry, Knt.; The Marquis of
Breadalbane ; The Earl of Charleville ; The Bishop of Cloyne ; The
Earl of Darnley; Lord De Dunstanville; Colonel Sir Augustus Simon
Frazer, K.C.B.; Major-General Hardwicke ; Captain Kater; Rev.
Thomas Robert Maithus, Thomas James Mathias, Esq.; William
George Maton, M.D.; Rey. Robert Morrison, D.D.; Michael Thomas
Sadler, Esq.; Richard Sharp, Esq. ; William Smith, Esq. ; Edward
Troughton, Esq.; Sir George Lemon Tuthill, Knt. M.D.; Ralph
Watson, Esq.

On the Foreign List.—Frederich Stromeyer.

The Secretary stated that of these only three, namely, Captain
Kater; John Brinkley, Lord Bishop of Cloyne, and Edward Trough-
ton, Esq. have contributed papers to the Royal Society.

Capt. Kater contributed the following papers, fifteen in number, to
the Philosophical Transactions.

1. On the light of the Cassegrainian Telescope, compared with that
of the Gregorian. (Phil. Trans. 1813, p. 206.)

Having remarked the superiority in the performance of a Casse-
grainian telescope over those of similar dimensions in the Gregorian
construction, Capt. Kater made a series of experiments to determine
the comparative excellence of these two methods of constructing that
instrument. From a mean of these experiments and from a consi-
deration of all the circumstances in which they were made, he con-
cludes that the comparative superiority of the Cassegrainian over the
Gregorian telescope of equal apertures and magnifying powers, is
as 20 to 11, or very nearly twice as great. He conjectures that the
superiority of illumination in telescopes of the former construction
may possibly depend on their being exempt from the mutual inter-
ference of rays meeting in the same point, as happens in the Grego-
rian telescope, when the small speculum receives the rays after they
have arived at the focus, and after they have become sufficiently con-
centrated to interfere with each other’s motion.

2. In a subsequent paper, the experimental research relating to
the same subject is further prosecuted, and the conclusion arrived at
is, that the illuminating power of the Cassegrainian telescope, as
compared to the Gregorian, is in the proportion of 24 to 1.

3. His next communication to the Society relates to ‘An improved
method of dividing Astronomical circles and other instruments.”
The general principle of the method there proposed is the same as
that of the beam compass; but the apparatus, instead of having points,
is furnished with two micrometer microscopes, adjustable to different
distances, as aliquot parts of the arc or line to be divided. Asa spe-
cimen of the method by which this apparatus is to be used, Capt.
Kater describes the series of divisions and subdivisions which he
thinks most convenient in a circle of two feet diameter.

4. The series of investigations in which Capt. Kater was engaged
for many years, relative to the pendulum, commences with a paper
entitled, “‘ An account of experiments for determining the length of
the Pendulum vibrating seconds in the Latitude of London.” To
ascertain with exactness the length of the seconds pendulum, an
object of considerable importance in Physical Science, was scarcely

152 Royal Society.

possible by the methods which had been before resorted to: for the
determination of the precise centre of oscillation of a body vibrating
as a pendulum, depending as it does on the regular figure and uni-
form density of that body, involves difficulties which might be re-
garded as insurmountable. Capt. Kater fortunately discovered the
means of solving this problem, by the application of a mathematical
property already known to belong to the centre of oscillation, but
which had never hitherto been practically employed with this view ;
namely, that this centre and the centre of suspension are reciprocal to
one another : that is to say, that if a body, vibrating as a pendulum, be
inverted, and suspended by its former centre of oscillation, its former
point of suspension will become its centre of oscillation in its new
position; and the vibrations in both positions will be performed in
equal times. This property, therefore, furnishes an easy method of
determining the exact distance between these two points, in a body
of any form, or however irregular may be the densities of its different
parts; for it will be only necessary, for that purpose, to provide a
second axis of suspension, placed by estimation very near to the
centre of oscillation, while the body is vibrating on its first axis,
and also capable of adjustment as to distance, and as to its being kept
in the line passing through the first axis, and the centre of gravity :
thus by repeated trials of the number of vibrations performed, in a
given time, by that body, when suspended on either of these two axes,
and by altering the place of the moveable axis until this number be-
comes the same in both positions, we obtain a final adjustment which
gives the exact distance between the centres of suspension and os-
cillation in that body; a distance equivalent to the length of a sim-
ple pendulum performing the observed number of vibrations in a cer-
tain time.

The mode of suspension adopted by Capt. Kater was the knife-
edge, of which he points out the various advantages and disadvan-
tages, and the methods he took for overcoming the difficulties of the
inquiry. By employing the method of coincidences he found that
the number of vibrations made by the pendulum in twenty-four
hours might be obtained to within half a second of the truth in the
space of eight minutes: and he then applied the usual correction
for the extent of the arc of vibration, and also for the height of the
place of observation above the level of the sea.

5. This paper was followed by another, ‘“‘ On the length of the
French Metre estimated in parts of the English Standard :’ in de-
termining which he employed the same micrometer microscopes as
were used in the pendulum experiments, bringing them alternately
over the metre and over the standard scale, placed in the same plane
parallel to and in contact with one another; care being taken that
their temperatures were the same.

6. In the following year (1819) Capt. Kater gives an ‘* Account of
experiments for determining the Variation in the Length of the Pen-
dulum vibrating Seconds, at the principal stations of the Trigonome-
trical Survey of Great Britain :” a paper which is full of laborious
calculations, founded on the observations therein detailed. The in-
vestigation of the diminution of terrestrial gravity from the equator

Royal Society. 15%

tothe pole is pursued by the comparison of determinations of the
length of the seconds pendulum at various stations: and is founded
on the theorem demonstrated by Clairaut, that the sum of the two
fractions expressing the ellipticity and the diminution of gravity
from the pole to the equator is always a constant quantity, and is
equal to 24 times the fraction expressing the ratio of centrifugal
force, and that of gravity at the equator. The extreme degree of
accuracy with which the force of gravitation may be determined by
the apparatus employed by Capt. Kater, suggested to him the possi-
bility of ascertaining by its means minute variations in this force
observable in passing through a country composed of materials of
yarious degrees of density: instances of the occurrence of which
are given in this paper.

7. Inthe year 1823, Capt. Kater communicated to the Royal Society
an account of experiments made with an invariable pendulum be-
longing to the Board of Longitude, by Sir Thomas Brisbane and
Mr. Dunlop, at Paramatta in New South Wales, and thence deduces
the fraction expressing the terrestrial compression.

8. In a paper which appeared in the Phil. Trans. for 1821 (p. 75.)
Capt. Kater gives an account of the comparison which he instituted
of various British Standards of Linear Measures for the purpose of
accurately examining the standard yard employed by General Roy,
in the measurement of a base on Hounslow Heath, as a foundation for
the trigonometrical operations carried on by the Ordnance through-
out the country. He found material differences to exist between the
standards of Sir George Shuckburgh, of Bird, of the Royal Society,
of General Roy’s, and of the one constructed by Ramsden, which
was used in the trigonometrical survey. Capt. Kater then proceeds to
investigate the effect of these differences on the figure of the earth.

9. Sir George Shuckburgh Evelyn kad, in the course of his inquiries
respecting a standard of weights and measures, examined with great
care the weights of a standard cube, cylinder, and sphere, and the
methods employed for this purpose had been minutely described ;
but the mode of ascertaining the dimensions of these bodies had not
been so fully detailed. Capt. Kater was accordingly desirous of re-
investigating this latter branch of the subject before the Commis-
sioners of Weights and Measures should make their final report. The
apparatus he employed for this purpose, and the results of his ex-
periments, are stated in a paper also published in the Philosophical
Transactions for 1821.

10. These researches were continued by Capt. Kater in the year
1825; and the details are given in a paper published in the Phil. Trans.
for 1826, and entitled «‘ An Account of the construction and adjust-
ment of the new standards of weights and measures of the United
Kingdom of Great Britain and Ireland.”

11. The series was completed in 1830 by the account he gives of
the detection of a source of error in estimating the standard of linear
measure, arising from the thickness of the bar, on the surface of
which the lines are traced, and of the means he took to obviate it.

12. The attention of Capt. Kater was at one time directed to the
Third Series. Vol. 8. No. 45. Feb. 1836.

154 Royal Society.

ascertaining the best kind of steel for the construction of a compass
needle, the most advantageous form to be given to the needle, and
the most effective mode of communicating to it magnetism. Many
curious and unexpected results were obtained in the course of this
investigation.

13. A remarkable volcanic appearance in the moon being observed
by Capt. Kater in February 1821, he communicated to the Society
shortly afterwards an account of the phenomenon, which was pub-
lished in the Phil. Trans. for the same year.

14. Oneof the greatest benefits conferred onscience by Capt. Kater
was his invention of the floating collimator, an instrument of which
the object is to determine the situation of the line of collimation of
a telescope attached to an astronomical circle, with respect to the
zenith or the horizon in any one position of the instrument; or in
other words, to determine the zero-point of the divisions on the limb:
an operation which was before usually performed by the use of the
level or the plumb-line, or by the reflexion of an object from the
surface of a fluid. Each of these methods was liable to many in-
conveniences and defects; all of which are avoided in the floating
collimator. The principles on which this instrument is constructed
are two; the first is the property of a telescope employed by Gauss,
and subsequently by Bessel, in virtue of which the cross wires of a
telescope adjusted to distinct vision on the wire, may be distinctly
seen by another telescope also similarly adjusted, at whatever distance
the telescope may be placed, provided their axes coincide ; in which
case the rays diverging from the cross wires of either telescope, will
emerge parallel from its object-glass, and will therefore be refracted
by that of the other telescope to its sidereal focus, as if they came
from an infinite distance. The other principle, which is employed
as a substitute for the common level, is the invariability with respect
to the plane of the horizon, of the position of a body of determinate
figure and weight, when floating on the surface of afluid. Thus the
telescope being attached to a box floating on mercury, and serving
as a stand to the telescope, may be fixed either in a horizontal or a
vertical position; in which latter case the reverse observations may
be made by merely turning the float half round in azimuth.

15. The later improvements made by Capt. Kater in the vertical
floating collimator are described by him in a subsequent paper pub-
lished in the Philosophical Transactions for 1828. Besides ob-
viating the sources of error arising from the necessity of transferring
the instrument to different sides of the observatory, and of taking the
float out of the mercury and replacing it at each observation, the
vertical floating collimator has the further advantage of being adapted
for use, not only with a circle, but also with a telescope, either of
the refracting or reflecting kind. Such a telescope, furnished with
a wire micrometer, and directed to the zenith, becomes a zenith
telescope, free from all the objections to which the zenith sector,
and the ordinary zenith telescopes with a plumb-line, are liable.
From the greater degree of precision attainable by the employment
of this instrument, from the facility of its construction, the readiness

Royal Society. — 155

of its application, and the economy of time resulting from its use, the
employment of the level and plumb-line may be wholly superseded.

John Brinkley, Lord Bishop of Cloyne, commenced his scientific
career, while Andrews Professor of Astronomy in the University of
Dublin, by a mathematical paper published in the Phil. Trans. for
1807, containing an investigation of the general term of an important
series in the inverse method of finite differences. In 1810 Dr. Mas-
kelyne, then Astronomer Royal, announced to the Society by the
communication of a letter from Dr. Brinkley, the supposed discovery
by the latter of the annual parallax of « Lyre, which he was confident
exceeds 2. In 1818 he reported having met with apparent motions
in several of the fixed stars which he could explain only by referring
them to parallax. Among these « Aquile exhibited the greatest
change of place. The observations made at the Greenwich obser-
yatory not being in accordance with those made at Dublin, Dr.
Brinkley, in a subsequent paper published in the Phil. Trans. for
1821, institutes a new series of observations with a view to discover
the source of this discordance. . In conclusion he states his inability
to discover any explanation of this difference, or to obtain any result
opposed to his former conclusions. He remarks, however, that the
discrepancies between his observations and those made at Greenwich
may by some be considered as showing the great precision of modern
observations, since the whole extent of the absolute difference is
only one second. In the last paper on this important subject, which
was published in the Phil. Trans. for 1824, Dr. Brinkley endeavours
to form a correct estimate of the absolute and relative degrees of
accuracy of the instruments at Dublin and at Greenwich. He first
considers the difference of parallax between y Draconis and a Lyre,
and secondly the absolute parallax of a Lyre.

Four other papers by the same author are also contained in the
Philosophical Transactions: the first in 1819, giving the results of
observations made at the observatory of Trinity College, Dublin, for
determining the obliquity of the ecliptic, and the maximum of the
aberration of light; the second, published in 1822, containing the
investigation of the elements of a comet observed by Captain Basil
Hall ; the third published in 1824, on the North Polar distances of
the principal fixed stars ; and the last, which appeared in 1826, com-
municating the results of the application of Capt. Kater’s floating
collimator to the astronomical circle at the observatory of Trinity
College, Dublin. He regards the results of these observations as
highly favourable to the principle of the collimator, which he con-
siders as a new astronomical power, and as even belonging to a more
advanced era of practical astronomy than the present.

Mr. Edward ‘Troughton is the author of a paper in the Phil. Trans.
for 1809, entitled “‘ An Account of a method of dividing Astronomical
and other instruments by ocular inspection; in which the usual tools
for graduating are not employed; the whole operation being so con-
trived, that no error can occur but what is chargeable to vision when
assisted by the best optical means of viewing and measuring minute
quantities.” The intrinsic excellence of Mr. Troughton’s method,

$2

156 Geological Society.

as detailed in this paper, consists in the process of examination
employed to correct the imperfections in laying down the divisions
by methods which give only approximate degrees of accuracy.

The Copley Medal, and the two Royal Medals for the present year
were delivered, pursuant to the awards made by the Council.

The ballot for the election of Council and Officers being taken,
the Scrutators reported the following as the result.

President: His Royal Highness the Duke of Sussex, K.G.—
Treasurer: Francis Baily, Esq.—Secretaries: Peter Mark Roget,
M.D.; John George Children, Esq.—Foreign Secretary : Charles
Konig, Esq.

Other Members of the Council: William Allen, Esq.; Rey. William
Buckland, D.D.; Samuel Hunter Christie, Esq.; Rev. James Cum-
ming; Davies Gilbert, Esq.; Joseph Henry Green, Esq.; Henry
Holland, M.D.; William Lawrence, Esq. ; John William Lubbock,
Esq. ; Herbert Mayo, Esq. ; Roderick Impey Murchison, Esq. ; Rev.
Robert Murphy, M.A.; Sir John Rennie; William Henry Smyth,
Capt. R.N.; Edward Turner, M.D.;. Rev. William Whewell.

GEOLOGICAL SOCIETY.

(Nov. 18, 1835, continued.) —< Geological notes made during a
survey of the East and West Coasts of South America, in the years
1832, 1833, 1834, and 1835, with an account of a transverse section
of the Cordilleras of the Andes between Valparaiso and Mendoza ;"’
by F. Darwin, Esq., of St. John’s College, Cambridge ; communicated
by Prof. Sedgwick, were afterwards read.

Prof. Sedgwick began by observing that the notes were extracted
from a series of letters (addresssd to Professor Henslow), containing
a very great mass of information connected with almost every branch
of natural history ; and that he had selected for the occasion those re-
marks only which he thought more especially interesting to the Geo-
logical Society.

Mr. Darwin’s first letter contained some account of St. Jago (one
of the Cape Verde Islands), which he visited early in 1832; and he
considered that he had good evidence of its recent elevation, as he
found on its surface beds of recent shells and corals considerably above
the actual level of the sea.

In various portions of the notes he shortly described the vast extent
of primary rocks along the shores of Patagonia, the existence of highly
crystalline schists in the Falkland Islands, alternating with micaceous
slaty sandstone, exhibiting the casts of bivalves (Terebratulz), and
encrinital stems, and a rock near Cape Famine containing “some sort of
Ammonites.’’ On the line of the western coast of South America, from
Chiloe to Tres Montes, he found a widely extended formation of mica-
slate, traversed and burst through by a grand transverse chain of gra-
nite, and penetrated by innumerable dykes of great complexity of
mineral structure.

From the position of the tertiary deposits, which exist on both sides
of the Southern Andes, he concludes that the primary chain must have

Geological Soctety. 157

had a great elevation anterior to the tertiary period: and he thinks
that a rough approximation may be made to the date of the com-
mencement of the volcanic period, by observing the first associa-
tion of streams of lava, with certain tertiary groups on the Patagonian
side.

A considerable portion of the extracts was devoted to a descrip-
tion of the great tertiary groups on both sides of the chain of the Andes.
Some of the details respecting the eastern side were derived from
observations made on the Rio Negro, and on the line of a transverse
section from Rio Santa Cruz to the base of the Cordilleras. These
exhibit the structure of what Mr. Darwin calls the great southern ter-
tiary formations of Patagonia.

The lowest of these formations appears to be of great extent and
thickness, and in one instance was found to contain a bed of an-
cient lava, which seemed to mark the commencement of the eruption
from the craters of the great chain of the Andes. It is character-
ized by a great Oyster, and by other shells and corals, some of which
belong to species now living on the neighbouring coasts. Over it is a
deposit which Mr. Darwin describes as chiefly composed of rolled por-
phyry pebbles, which he had himself traced for more than 700 miles.
Overlying all the rest, and at a greater elevation above the level of
the sea, were beds of recent shells, identical in species with the lit-
toral shells of the neighbouring shores. Among these, he more espe-
cially notices a widely extended bed of Muscles, which still retain
their blue colour, and emit an animal smell when thrown in the fire.
From these facts, he thinks the tertiary deposits of Patagonia may be
separated into distinct periods, somewhat similar to those derived by
Mr. Lyell from a comparison of the newer deposits of Europe: and
in making the transverse section, he thought that he saw traces in the
valley of Santa Cruz of an ancient channel, which must have traversed
a great portion of the south part of the continent before the elevation
of the tertiary groups.

In noticing the groups on the western side of the Andes, he de-
scribes an old tertiary deposit (eocine or miocene ?) south of Rio
Maypo, and abundance of recent shells 1300 feet above the same level.
He also describes the association of lava with beds containing recent
shells in the island of Chiloe. Among other facts, he notices the ap-
pearance of pitchstone among the beds of lava, and the occurrence of
a forest growing over a bed of recent oysters 350 feet above the ac-
tual level of the sea. All these recent shells are the littoral shells of
the neighbouring shores ; from which he concludes that the elevation
must have been gradual, or by successive hitches, similar to those by
which the coast of Chili and, more recently, the coast of Chiloe have
been unquestionably elevated.

In addition to these very remarkable notices, Mr. Darwin mentions
other fertiary deposits at Chiloe and Conception, composed of beds
of sandstone and carbonaceous shale without shells, but containing
many silicified trunks of dicotyledonous trees, and alternating with
beds of lava.

During the progress of the four years’ survey (in addition to the

158 Geological Society.

traverse above mentioned), Mr. Darwin crossed from Rio Negro to
Buenos Ayres by Sierra de la Ventana, a chain almost unknown to
geographers. He found two immense collections of large bones (of
Mastodons) near Santa Fé, but in a condition not to admit of their
being removed. He also found bones of a species of Mastodon at
Fort St. Julian, S. lat. 50°, and more than 600 miles from the former
localities. In one instance the bones appear to have been associated
with marine shells. In the gravel of Patagonia he also found many
bones of the Megatherium and of five or six other species of quadru-
peds, among which he has detected the bones of a species of Agouti.
He also met with several examples of the polygonal plates of the Me-
gatherium, which at first induced him to regard the animal as a gigan-
tic Armadillo. A very large collection of tiese fossils has been sent
to England, and are in the custody of Professor Henslow till Mr, Dar-
win’s return.

Professor Sedgwick concluded by reading extracts from two letters
describing a section transverse to the Andes, extending from Valpa-
raiso to Mendoza. The Cordillera is here composed of two separate
and parallel chains. The western chain is composed of sedimentary
rocks, distinctly stratified, and resting on granite. ‘The sedimentary
rocks (composed of red sandstone, conglomerate, gypsum, &c.) are
violently contorted, and dislocated along parallel north and south
lines, and as they approach the granite, become so crystalline that they
cannot be distinguished from the porphyritic dykes by which they are
traversed.

Following the line of section, Mr. Darwin found, at the Pass of
Puquenas, elevated 12,000 feet above the sea, that the red sandstone
was replaced by a black rock, like clay slate and pale limestone, con-
taining numerous impressions of shells ; a Gryphza? is the most abun-
dant; but he also found Ostrea, Turritella, Ammonites, and a small
bivalve (‘Terebratula?).

At the Portillo Pass is a conglomerate resting on micaceous sand-
stone, and traversed by great veins of granite. But at the Uspellata
Pass (in the eastern chain), he found highly crystalline and felspa-
thic rocks, regularly bedded, and resting on granite, the peaks of
which reach the elevation of 14,000 feet. A wider examination of
the overlying groups convinced him, not only that they were more re-
cent than the western chain (being partly made up of its debris), but
that they were of the same age with certain tertiary formations above
noticed. For example, he discovered along the line of section, in
the eastern chain, beds of sandstone, with silicified trunks of dico-
tyledonous trees, and beds of carbonaceous shale, resting on an an-
cient stream of lava, and surmounted by black augitic lava, 2000 feet
thick; over all these were five grand alternations of black volcanic
rocks and sedimentary deposits, amounting to several thousand feet
in thickness. This series, in its structure and fossils, is considered as
identical with certain tertiary deposits of Patagonia, Chiloe and Con-
ception; for it loses its mineral character only where it approaches
the granite ; in which case it is shattered, contorted, and traversed by
great veins rising out of the central mass; and its several beds, as

Geological Society. 159

well as the fossils they contain, become entirely crystalline. Mr. Dar-
win further states, that this singular overlying group contains very nu-
merous veins of copper, silver, arsenic, and gold, which may be traced
down to the granite ; and as a general conclusion, he expresses his
conviction that the granite (now rising into central peaks 14,000 feet
in elevation), must have been in a fluid state since the tertiary group,
above described, was deposited.

Dec. 2nd.—A letter was first read from Capt. Belcher, R.N.,
F.G.S., addressed to Woodbine Parish, Esq., Sec. G.S., dated 10th
of March, 1835, inclosing two others from Lieut. Bowers, R.N.,
and H. Cuming, Esq.

These letters referred to the effects produced at Valparaiso by the
earthquake of November 1822.

Capt. Belcher says that he had carefully searched the Remark-
Books of His Majesty’s vessels stationed on the Chilian coast, between
September 1822 and March 1823, but had not found a notice in any
way connected with the Port of Valparaiso. He therefore infers that
no British ship of war was present; but he thinks that if the distur-
bance produced by the earthquake of November 1822 had been of a
nature to alter the soundings, or even induce the residents to attach
importance to any known charges, they would have formed a subject
of special communication by the commanders of ships of war.

Lieut. Bower states in his letter, dated 7th of March 1835, that he
was not at Valparaiso at the time of the earthquake, but arrived from
England in February 1823, and found everything in the same situa-
tion as when he quitted it twelve months previously. He adds, that
since the earthquake, the water has gradually receded from the part
situated between the landing-place and the market-place, and that a
row of stores and substantial dwellings had been erected where the
sea formerly flowed.

Mr. Cuming’s letter is dated 5th of March 1835.

The writer arrived at Valparaiso in January 1822, and resided there
constantly until 1827, and from the latter period, with occasional ab-
sences, till May 183]. At the time of the earthquake, he lived in the
Plaza Mayor, near the landing-place at the Arsenal, and his house
was destroyed by the first shocks. He did not go to the beach during
the night, but was informed that the sea had retired a considerable
distance, and had returned with great force. On the morning of the
20th he noticed the effects, but found nothing more than a high tide.
He never heard of the rocks having been heaved up, or of the perma-
nent retirement of the sea, until the publication of Mrs. Graham's
work, to the statements contained in which neither he nor his friends
could subscribe.

Mr. Cuming’s pursuit of conchology and natural history generally,
caused him to visit frequently the rocks and inlets with which the
northern and southern parts of the Bay abound ; but though the rocks
were covered with Fuci, Patellz, Chitons, Balani, &c., yet he never
perceived the least difference in their appearance from the date of his
arrival to his finally quitting Valparaiso. He mentions particularly,
as points which he often examined, the Caleta, the Quebrada de Dios,

160 Geological Society.

and the Cruz de Reyes. He also never found the least trace of the
above productions, except in situations covered by the tide.

After the earthquake, Mr. Cuming resided in a house in the Arse-
nal, where the spring tides came up to the same mark as they did pre-
viously to that event. He refers especially to the tides of 1822 and
1823.

Another circumstance which convinced Mr. Cuming that no change
of level had taken place was the existence of a small detached rock
opposite the Estanco, half-way between the Custom-house and the
Market-place, and about fifty yards from the walls at half tide. From
this rock he had often taken Concholepas Peruvianu previously to the
earthquake, and subsequently it retained the same position.

The vessels occupied the same anchorage as they did before Novem-
ber 1822; and nautical men affirmed that there was not the least dif-
erence in the depth of the water in any part of the Bay.

The opinion that a change had taken place in the relative level of
land and sea, Mr. Cuming conceives originated in the accumulation
of detritus at points where the tide flowed anterior to the earthquake,
and on which houses, and even small streets have been since erected.
Though these accumulations appear to have been going on between
50. and 80 years, yet they were smail previously to the violent rains
in June 1827, which brought down into the bay the loose granitic
soil of the hills and the ravines. This detritus has since been thrown
up by the tides, and formed into a firm open space exceeding 250 feet
in breadth, on which the buildings have been erected.

The quantity of matter thus carried into the Bay has not affected
the anchorage, and Mr. Cuming, when dredging within two hundred
yards of low-water mark, never found a grain of decomposed granite,
or any kind of recent soil, but fine sandy mud, well stocked with se-
veral species of shells of mature growth.

Both to the northward and southward of Valparaiso, where the
coast is open, namely, at Lagunilla, Vina del Mar, Con-Con, and
Quintero, the sea has thrown up high banks of sand, many feet above
the ievel of the land behind them, and reaching inland from 1000 to
2000 feet, and at Quintero to a much greater extent. At this place
the sand contains beds of shells “in a semi-fossil state.”” Mr. Cuming
visited these localities previously to the earthquake, and often subse-
quently, but never saw a shell beyond the range of high water, except
those in the state above mentioned, and the owners declared that no
change had taken place.

Mr. Cuming also states that about 70 years since, he believes at
the same time that Conception was visited by an earthquake, Valpa-
raiso was also visited. The sea retired to a very great distance, and
the reflux was so violent that it destroyed all the houses, carrying the
boats and canoes to the church of San Francisco, which is about a
pool of a mile on a gradual ascent from where the tide usually

ows.

A paper on the effects of the Earthquake-waves on the Coasts of
the Pacific, by Woodbine Parish, Esq., Sec. G.S., was afterwards read,
and will be inserted at length in our next number.

ae Ca

ZOOLOGICAL SOCIETY.
(Continued from vol. vii. p. 534.)

Oct. 27, 1835.—The following ‘‘ Observations on the Habits, &c. of
amale Chimpanzee, Troglodytes niger, Geoff., now living in the Mena-
gerie of the Zoological Society of London, by W. J. Broderip, Esq.,
V.P.Z.S., F.R.S., &c.,” were read :—

«The interesting animal whose habits in captivity I attempt to
describe, was brought to Bristol in the autumn of this year by
Capt. Wood, from the Gambia coast. The natives from whom
he received it, stated that they had brought it about one hundred
and twenty miles from the interior of the country, and that its
age was about twelve months. The mother was with it, and, ac-
cording to their report, stood four feet six inches in height. Her
they shot,—and so became possessed of her young one; and those
who have seen our animal will well understand what Dr. Abel
means, when, in his painful description of the slaughter of an Asi-
atic Orang (Pithecus Satyrus, Geoff.), he observes that the ges-
tures of the wounded creature during his mortal sufferings, the hu-
man-like expression of his countenance, and the piteous manner of
his placing his hands over his wounds, distressed the feelings of those
who aided in his death, and almost made them question the nature
of the act they were committing. During the period of his being
on ship-board, our Chimpanzee was very lively. He had a free range,
frequently ran up the rigging, and showed great affection for those
sailors who treated him kindly.

«‘T saw him for the first time on the 14th instant, in the kitchen
belonging to the Keeper’s apartments. Dressed in a little Guernsey
shirt, or banyan jacket, he was sitting child-like im the lap of a
good old woman, to whom he clung whenever she made a show of
putting him down. His aspect was mild and pensive, but that of a
little withered old man; and his large eyes, hairless and wrinkled
visage, and man-like ears, surmounted by the black hair of his head,
rendered the resemblance very striking, notwithstanding the de-
pressed nose and the projecting mouth. He had already become
very fond of his good old nurse, and she had evidently become at-
tached to her nursling, though they had been acquainted only three
or four days; and it was with difficulty that he permitted her to go
away to do her work in another part of the building. In her lap he
was perfectly at his ease; and it seemed to me that he considered
her as occupying the place of his mother. He was constantly reach-
ing up with his hand to the fold of her neck-kerehief, though when
he did so she checked him, saying ‘“‘ No, Tommy, you must not pull
the pin out.” When not otherwise occupied, he would sit quietly in
her lap, pulling his toes about with his fingers, with the same pensive
air as a human child exhibits when amusing itself in the same
manner. I wished to examine his teeth; and when his nurse, in
order to make him open his mouth, threw him back in her-arms and
tickled him just as she would have acted towards a child, the carica-
ture was complete.

“1 offered him my ungloved hand. He took it mildly in his, with

162 Soologicul Society.

a manner equally exempt from forwardness and fear ;—examined
it with his eyes, and perceiving a ring on one of my fingers, sub-
mitted that and that only to a very cautious and gentle examination
with his teeth, so as not to leave any mark on the ring. I then offered
him my other hand with the glove on. This he felt, looked at it,
turned it about, and then tried it with his teeth. His sight and his
ordinary touch seemed to satisfy him in the case of a natural surface,
but, as it appeared to me, he required something more to assure his
senses when an artificial surface was presented to him; and then he
applied the test of his teeth.

‘‘ At length it became necessary for his kind nurse to leave him;
and after much remonstrance on his part, she put him on the floor.
He would not leave her, however, and walked nearly erect by her side,
holding by her gown, just like a child. At last she got him away by
offering him a peeled raw potato, which he ate with great relish,
holding it in his right hand. His keeper, who is very attentive to
him, and whom he likes very much, then made his appearance, and
spoke to him. Tommy (for by that name they call him) evidently
made an attempt to speak too, gesticulating as he stood nearly erect,
protruding his lips, and making a hoarse noise “‘ hoo-hoo””’ somewhat
like a deaf and dumb person endeavouring to articulate. He soon
showed 'a disposition to play with me, jumping on his lower extremi-
ties opposite to me like a child, and looking at me with an expression
indicating a wish for a game of romps. I confess I complied with
his wish, and a capital game of play we had.

“«On another occasion, and when he had become familiar with me,
I caused, in the midst of his play, a looking-glass to be brought, and
held it before him. His attention was instantly and strongly ar-
rested: from the utmost activity he became immoveably fixed,
steadfastly gazing at the mirror with eagerness and something like
wonder depicted on his face. He at length looked up at me—then
again gazed at the glass. ‘The tips of my fingers appeared on one
side as I held it—he put his hands and then his lips to them—then
looked behind the glass—then gazed again at its surface—touched
my hand again, and then applied his lips and teeth to the surface of
the glass—looked behind again, and then, returning to gaze, passed
his hands behind it, evidently to feel if there was anything substan-
tial there. A savage would have acted much in the same way,
judging from the accounts given of such experiments with the un-
tutored natives of a wild and newly discovered land.

“I broke a sugared almond in two, and, as he was eating one half,
placed the other, while he was watching me, in a little card-box
which I shut in his presence—as soon as he had finished the piece
of almond which he had, I gave him the box. With his teeth and
hands he pulled off the cover, took out the other half, and then laid

the box down. He ate the kernel of this almond, rejecting the .

greatest part of the sugary paste in which it was incased, as if it had
been a shell: but he soon found out his error; for, another almond
being presented to him, he carefully sucked off the sugar and left
the kernel.

I then produced a wine-glass, into which I poured some racy sherry,

_

Mr. Broderip on the Habits of the Chimpanzee. 163

and further sweetened it with sugar. He watched me with some
impatience, and when I gave him the glass he raised it with his
hands to his lips, and drank a very little. It was not to his taste,
however, for he set down the glass, almost as full as he had taken
it up; and yet he was thirsty, for I caused a tea-cup with some
sugared warm milk and water to be handed to him, and he took up
the cup and drained it to the last drop.

«<T presented him with a cocoa-nut, to the shell of which some of the
husk was still adhering: the tender bud was just beginning to push
forth—this he immediately bit off and ate. He then stripped off some
of the husk with his teeth, swung it by the knot of adhering husk-
fibres round his head, dashed it down, and repeatedly jumped upon
it with all his weight. He afterwards swung it about and dashed it
down with such violence that, fearing his person might suffer, I had
it taken away. A hole was afterwards bored through one of the
eyes, and the cocoa-nut was again given to him. He immediately
held it up with the aperture downwards, applied his mouth to it, and
sucked away at what milk there was with great glee.

“As I was making notes with a pencil, he came up, inquisitively
looked at the paper and pencil, and then took hold of the latter.
Before I gave it up, I drew the pencil into the case, foreseeing that
he would submit the pencil-case to examination by the teeth. Im-
mediately that he got it into his possession, he put the tip of his
little finger to the aperture at the bottom, and having looked at it,
tried the case with his teeth.

“While his attention was otherwise directed I had caused a
hamper containing one of the Pythens to be brought into the room
and placed on a chair not far from the kitchen dresser. The lid
was raised, the blanket in which the snake was enveloped was
opened, and soon after Tommy came gamboling that way. As he
jumped and danced along the dresser towards the basket, he was all
gaiety and life. Suddenly he seemed to be taken aback, stopped—
then cautiously advanced towards the basket, peered or rather craned
over it—and instantly with a gesture of horror and aversion, and the
ery of Hoo! hoo! recoiled from the detested object, jumped back
as far as he could, and then sprang to his keeper for protection. He
was again put down, his attention diverted from the basket, and,
after a while, tempted to its neighbourhood by the display of a fine
rosy-cheeked apple, which was at last held on the opposite rim of
the hamper. But no—he would evidently have done a good deal
to get at the apple; but the gulf wherein the serpent lay was to be
passed, and after some slight contention between hunger and horror,
off he went and hid himself. [ then covered up the snake, and after
luring him out with the apple, placed it on the blanket—No. I then
shut down the lid—still the same desire and the same aversion. I then
had the hamper, with the lid down, removed from the chair on which
it had been placed to another part of the room. The apple was again
shown to Tommy and placed on the lid. He advanced cautiously,
looking back at the empty chair and then at the hamper: he ad-
yanced further with evident reluctance, but when he approached

164 Roological Soctety.

near he peered forward toward the basket, and, as if overcome by
fright, again ran back and hid himself under his cage.

“IT now caused the hamper with the serpent to be taken out of
the room. Our friend soon came forward. I showed him the apple
and placed it on the chair. He advanced a little, and I patted his
head and encouraged him. He then came forth and went about the
room, looking carefully as if to satisfy himself that the snake was
gone—advanced to the chair more boldly,—looked under it—and
then took the apple and ate it with great appetite, dancing about
and resuming all his former gaiety.

“We know that there are large constricting serpents in Africa;
and as the animal must have been very young when separated from
its parent, I made this experiment in particular to try his instinct:
it succeeded to the entire satisfaction of the witnesses who were
present.

‘‘He manifested aversion to a small living tortoise, but nothing
like the horror which he betrayed at sight of the snake. I was in-
duced to show him the former by the account of the effect produced
by Testudinata on the Asiatic Orang, whose habits are so admirably
described by Dr. Abel and Captain Methuen, who brought the ani-
mal to England.

“Tommy, among other exercises, is very fond of swinging. He
places himself on the swing, generally in a sitting posture. holding
on each side with his hands. He not unfrequently puts up his feet
and grasps the cord on either side with them too, appearing more at
home on his slack rope than Il Diavolo Antonio himself.

«‘ James Hunt, one of the keepers, has observed him frequently
sitting and leaning his head on his hand, attentively looking at the
keepers when at their supper, and watching, to use Hunt’s expres-
sion, ‘‘every bit they put into their mouths.” Fuller, the head
keeper, informs me that our Chimpanzee generally takes his rest in a
sitting posture, leaning rather forward with folded arms and some-
times with his face in his hands. Sometimes he sleeps prone, with
his legs rather drawn up, and his head resting on his arms.

“Of the black Orangs which I have seen, Tommy is by far the
most lively. He is in the best health and spirits, and is a very dif-
ferent animal from the drooping, sickly Chimpanzees that I have
hitherto seen. A good deal of observation made on the Asiatic
Orangs which have been exhibited in this country, satisfies me that
the intelligence of the African Orang is superior to that of the Asiatic.
This intelligence is entirely different from that of a well-educated
dog or a mere mimic, and gives me the idea of an intellect more re-
sembling that of a human being than of any other animal, though
still infinitely below it.

«The Pygmy of Tyson and the black Orang dissected by Dr.
Traill, and so well described by him in the ‘ Wernerian Transactions,’
are both stated to have progressed generally by placing their bent
fists on the ground and so advancing: indeed Dr. Traill says that
the individual which he saw never placed the palms of the hands on
the ground. The progression of Dr. Abel’s red or Asiatic Orang is

Mr. Broderip on the Habits of the Chimpanzee. 165

described to have been after the same fashion. Whether it is that
our Chimpanzee is in better health and more lively, I know not, but
he certainly passes a great deal of his time in a position nearly ap-
proaching to erect, nor does he, generally, place the bent knuckles
to the ground. He will often stand on the top of his cage and
apply the palms of his hands to the smooth surface of the wall against
which it stands. It is said that a spectator who saw him thus em-
ployed, with his back to the company, dressed in his little banyan
jacket and woollen cap, was told by a companion to look at the
monkey, as he profanely called him. ‘‘ Where is he?” was the re-
ply. ‘“ Why there on the top of the cage,” was the answer. ‘‘ What!”
said the first, ‘‘that little man who is plastering the wall?”

«Tommy does not like confinement, and when he is shut into his
cage, the violence with which he pulls at and shakes the door is very
great, and shows considerable strength; but I have never seen him
use this exertion against any other part of the cage, though his
keeper has endeavoured to induce him to do so in order to see
whether he would make the distinction. When at liberty he is ex-
tremely playful, and, in his high jinks, I saw him toddle into a
corner where an unlucky bitch was lying with a litter of very
young pups, and lay hold of one of them, till the snarling of the
mother and the voice of his keeper, to which he pays instant respect,
made him put the pup down. He then climbed up to the top of the
cage where the Marmozets were, and jumped furiously upon it, evi-
dently to astonish the inmates, who were astonished accordingly, and
huddled together, looking up in consternation at this dreadful pother
o’er their heads. Then he went to the window, opened it and looked
out. I was afraid that he might make his escape: but the words
“Tommy, no!” pronounced by his keeper in a mild but firm tone,
caused him to shut the window and come away. He is in truth a
most docile and affectionate animal, and it is impossible not to be
taken by the expressive gestures and looks with which he courts
your good opinion, and throws himself upon you for protection
against annoyance.

«« Tt must be remembered that though I have not observed our Chim-
panzee to progress with his bent knucklestouching the ground, as [ have
seen the Asiatic Orangs move, there is no reason for doubting the ac-
curate descriptions of Tyson and Dr. Traill. I consider it as my pro-
vince to relate faithfully what I saw, and I have only seen our Chimpan-
zee, as yet, in a small room, where a very few paces will bring him toa
chair, a leg of a dresser, or some other piece of furniture which en-
ables him to call into action his prehensile hands and feet, so admi-
rably adapted to his arboreal habits. The narrowness of the pelvis,
the comparatively inferior development of the glutei* and gastro-
enemii muscles, and other peculiarities of conformation so ably

* This must be understood as limited to a comparison with the same
muscles in man; for there is in the Chimpanzee as Mr. Owen observes, “ a
persion for a more extended attachment for the glut@i muscles, in a greater

readth of the ilia between the superior spinous processes, than is observed
in the inferior Simi.”

166 Zoological Society.

pointed out by Tyson, Dr. Traill, and others, but more particularly by
Mr. Owen, show that the erect, or, more properly speaking, the semi-
erect position, is not the natural one; though my observations upon
living Asiatic Orangs and Chimpanzees accord with the inference
drawn by Mr. Owen from the comparative organization of the lat-
ter, viz. that the semi-erect position is more easily maintained by the
Chimpanzee than by any of the other known Simie.

«The great intelligence and strength of the individual now in the
menagerie of the Society, added to the state of its dentition, raised
a doubt in my mind as to the accuracy of the report of its age; and I
wrote to my friend Mr. Owen my suspicion that he might be older
than he was said to be. I received the following reply, in which so
much valuable information is concentrated that I feel it to be due to
those who may think this memoir worthy of attention to give it as
I received it.

‘21st October, 1835.

««« My dear Broderip,—I feel that we have no data towards deter-
mining with certainty the exact age of the young Chimpanzee at the
Gardens: its present state of dentition corresponds to that which
our own species presents during the period of from 2 to 7 years, viz.
incisors 4, canines $, molars 4, all of which belong to the deci-
duous series. The deciduous canines appear in the human jaws be-
fore the completion of the second year ; and those of the Chimpanzee
are certainly the temporary ones, but are protruded by the enlarged
germs of the permanent teeth behind them, so as to appear larger
than natural. From this circumstance and from the space already
existing beyond the deciduous molars, I infer that the appearance
of some of the permanent teeth is near at hand; and we may still
see an additional molar protruding in each jaw before the winter is
over, if the poor animal should survive that period.

«« «The human child acquires the corresponding permanent molars
at the seventh year; and from the appearances on the jaws of our
Chimpanzee I conclude that its age tallies with that of 5 or 6 years in
us. But analogy will be dangerous ground for an inference as to
precise age, since it is by no means improbable that, where the brain
is so much less developed, the full use of it may be much earlier ac-
quired, such as it is; and that the shedding of the teeth may take
place at a proportionally early period.

‘ Believe me, &c. * RicHarp Owen.’

““T now proceed to the measurements of our male specimen,
premising that the operation was a work of no small difficulty in
consequence of the restlessness of the animal. Indeed I am not sure
now about the height, though I am confirmed in the measurements
by Mr. Miller and Fuller. The Chimpanzee would keep drawing up
his legs and putting the musculus scansorius detected by Dr. Traill
into action; and it was not practicable to make him stand or lie
quite straight with his legs entirely extended.

Height from the heel to the top of the head........ 2 0
Circumference of the bottom of the breast.......... Tees

Mr. Broderip on the Chimpanzee. 167
Bt an.
Gircimereretice round the nips. fo 2 1 34
of the head round the eyes andears.. 1 3
Genie of the mow. 92". 9 NP eae O 3+
Height from the middle of the upper lip to the eyebrows 0 34
Length from the eyebrows to the occtput .... ..... 0 7
Diameter of theearmpwards = 2S5-. US Pee. Ome
Transverse diameter of the same.................. One.
Circumference of the external edge of the same...... O 63
of that part which adheres to the head O 42
Height from the upper point of the pubis to theclavicle O 10}
Distance between the navel and sternum .......... QO 42
Distance between the navel and pubis ............. O 34
ao NES Secs beige bose awe QO 4
Length of the arm from the shoulder to the end of leo
r
PM HUD Cte stem ee vane Safes a etcacts omen
Cireumiferente'of theiarm.s 4.) 4... Peel. 2.) 8 0 6
of the forearm four inchesabove thewrist O 6}
Length of the hand from the wrist to the end of the ae
PEM CD Ee ror teehee ch Co aac see \ fia
Gircumterence orthe hand s.r ee ee. Oe QO 44
wo th 2g hay hc 5 00s OL ee a gee a PA aye O 14
RECONCMINEET weet woe cele ete O25
a middle finger... eee ee 0 Sz
GUT EM MAP Er: eins oss oe css oe oats ee Ore
PIL UITHILE OL enero rn en Tela eee bys tretcvere ane core Cr oy
Circumference of the thumb and little finger ....... O° '13g
————— OLB CU MEFCUN Nts tenes otis else ccs a'e Or a=
Mae OU CN PIMIES fee's sto cyaN ere ore Gia es exh a0 alae tiem O 2%
PM EMEMMPECLGES ce el ce ete CA sete as ape el Seale ae OF ae
Height from the heel to the extremity of the thigh-bone 0 114
Length from the heel to the extremity of the middle 5
PRES CEE oi orele cic soe aes aos tee teeter oan <i a,e4s ae’ oe :
@ircumterence or the thigh: oars octets 6 a ec eite O 8
leg, at its thickest part........ O 6
foot, taken from the origin of 0 5
PUNEMETEMNEEES scr isco cho cus, vcettlay® suoleesuste dt caveae os *
Memon or the tramp. Or preat t0€...0 .. 262 ar ese. oe Q 17
— BOCENIG IG aicttie’s tatty aetna sie cent racee 0 2
——— EEIEMSLOCY «| nenere Mey elevite titastes alana ate eons (Oe Bat
c——MEDDICLI TOE Ta scsi: one cane helms ee tye oe Os
ithind (61 ROY ofp Auta bes telat, Seal Ne Sale. bol Riba a Me Oz
Greatest breadth of the sole at the origin of the thumb \ 0 2:
RAIS A a ora OE tt BE se ert gb 5.03 0p acer 4
——$$ near the heel .......... Osa
Circumference of the great toe at the largest point.... 0 12
EDETACOER Gy Moet). rcletacene uta oe O 1+

“On referring to the dimensions given by Daubenton we shall
be struck with the stoutness of our specimen as compared with that
of the individual which was the subject of his observations.

168 Intelligence and Miscellaneous Articles.

«Tt was my intention to have added a particular description of the
individual which has been the subject of this memoir; but on care-
fully inspecting the animal I find Dr. Traill’s elaborate description so
accurate—(there really is no difference but sex at present)—that I
should be needlessly occupying space if I inserted my own; and I
beg, therefore, to refer the reader to that gentleman’s highly valuable
papers in the ‘ Wernerian Transactions’.

«« Since writing the above the cage in which our animal was con-
fined has been enlarged and several barked branches have been nailed
to a stem so as to form an artificial tree. ‘These branches he ascends
with great activity, and frequently swings with his head downwards,
holding on by his lower extremities, and recovering himself with
greater agility than any rope-dancer.”—W. J. B.

XX XI.—Zntelligence and Miscellaneous Articles.

OPTICAL EXPERIMENT.
GPE following description of an optical experiment will no doubt in-
terest many of the readers of the London and Edinburgh Philo-
sophical Magazine: this experiment is easily performed, and may be
seen by several persons at the same time.

Mr. Lipkens, of Voorburg, it is believed, was the first to notice the
phenomenon, and on a recent visit to this country was so kind as to
call the attention of the writer to the fact, and to allow of its being
published in England.

The apparatus which may be most advantageously employed for
the development of this phenomenon, consists of astout hollow sphe-
rical glass vessel about six or eight inches in diameter, with an open
neck, to which should be attached, by cement or otherwise, a brass
cap, furnished with a stop-cock.

The experiment is performed thus: Pour into the globe a small por-
tion of water, and then, by means of the lungs or of a condensing
syringe, force air into it, the quantity being adjusted according to
the strength of the globe. Ifa lighted candle or lamp be so placed
that the flame may be viewed through the horizontal diameter of the
spherical vessel while it is charged with condensed air, and supported
at the same time in such a position that the neck with the brass cap
and stop-cock are uppermost, then every time the finger of the operator
placed upon the opening of the stop-cock so as to close it, is raised,
a sudden and rapid escape of a portion of the confined air or vapour
taking place, it will be observed that the image of the flame will ap-
pear with a halo of coloured light. Generally the first escape gives
a light yellow halo surrounded with a red circular fringe; the se-
cond liberation a blue halo; the third shows a green halo, and in
most cases the haloes are encompassed by a series of coloured rings.

Before all the condensed air is allowed to escape, the water in the
globe may be shaken about in it without any detriment to the ex-
periment.

The phenomena exhibited by this experiment (if dexterously per-

Intelligence and Miscellaneous Articles. 169

formed) give results something similar to those noticed on the egress
ofa polarized ray of light after it has traversed at right angles a po-
lished plate of quartz of a given thickness, and cut perpendicularly to
the axis of double refraction. For it is well known, that when a ray
has thus passed through, if examined by an analysing eye-piece, it
exhibits a variable coloured central aperture with rings, the tints of
the aperture changing according to the position of the polished cry-
stalline plate with regard to the eye-piece.

So far as the writer was enabled to experiment with his globe he
found the results capricious, for he never could predict what would be
the precise colour of the first halo, but the mean of a number of ex-
periments gave the order of changes as above related.

Mr. Lipkens favoured the writer in French with his ideas on the
subject, which may be translated thus: The cause of the phenomenon
presented by the experiment is evidently due to vapours formed in
the glass globe by a change of temperature in the air which it in-
closes, and which takes place, as we know, every time that there is a
rapid change in the tension of that air.

The variety of the colours of the haloes which are obtained by al-
lowing the compressed air to escape successively in the way described,
might depend on the dimensions of the vesicular molecules of the
water, or on the thickness of the envelopes of these molecules. Mr.
Lipkens then states, that as far as he knew, the necessary means
required to obtain one centra! colour rather than another, are not
yet discovered, and consequently it appears that were philosophers
to discover and give a general explanation of the phenomena in ques-
tion, their time would not be misemployed.

London, Jan. 27, 1836. F. W.

THULITE AND STROMITE.

In a list of minerals appended some years since to a volume on
crystallography, I gave 92° 30’ and 87° 30’ as the angles of this
mineral; and I did so upon the authority of some fragments of a red
mineral received by Mr. Heuland from Sweden, having ‘“ Thulite”
written by Ekeberg on the paper containing them. But I have since
found that the fragments I measured were bisilicate of manganese,
or, as I have named it, Strdémite, of which, or of thulite, I had not at
that time seen any other specimen. I shall feel obliged to the Editors
of the Phil. Mag. if they will insert this correction. H. J. Brooke.

ON THE MIRAGE, AS SEEN IN CORNWALL.
To the Editors of the Phil. Mag. and Journal of Science.

GENTLEMEN,

The mirage is so frequently seen in this hilly county, that I did
not think of sending you the following notice of one which I lately
saw, until I recollected that some eminent travellers who had wit.
nessed similar phenomena abroad have deemed them worthy of a
full description in their narratives.

Third Series, Vol. 8, No. 45. Feb. 1836, Tr

170 Intelligence and Miscellaneous Articles.

Early in the morning of the 25th of September last, while on the
coach upon the high ground about a mile and a half west of Truro, I
observed towards the south-east, in a valley ,the appearance of a beau-
tiful lake, or inlet of the sea, winding round a distant point, and then
branching off into several little creeks or sheets of water, which soon
lost themselves among the windings of the contiguous vales. The
nearest part of this imaginary water was about half a mile from the
coach, and so much did it resemble an inlet of the sea, that a fellow
passenger, who was a stranger to the locality, could not be per-
suaded for some time but that it was really such.

The sun had been up about an hour, and the morning was calm
and unusually cold. The thick fog which had risen from the valleys,
had not quite reached the tops of the hills, and its surface seemed
as level as the ocean ; so that while reflecting the unclouded beams
of the sun, it couid not possibly be distinguished from an inlet of
the sea. I am, Gentlemen,

Your very humble Servant,

Redruth, 9th December, 1835. R. Epmonps, Jun.
SUBSIDIARY HYPOTHESIS TO THE ELECTRO-CHEMICAL THEORY
OF SIR H. DAVY.

The beautiful theory advanced by Sir H. Davy to account for che-
mical affinity, by ascribing it to electrical agency, has many suppor-
ters, because it is a theory founded on extensive observation and nu-

merous facts. It supplies chemists with a principle capable of ac-—

counting for the phenomena ascribed to affinity, and affords a con-
sistent explanation of the chemical agencies of the Voltaic apparatus.
Dr. Turner briefly embodies the substance of the theory as follows:
**What chemists term chemical attraction or affinity is under this
point of view an electrical force arising from particles of a different
kind attracting each other in consequence of being in opposite states
of electrical excitement. Substances which have a disposition to
unite, assume opposite electrical conditions when brought into con-
tact, and the very existence of the compound depends on its elements
retaining their state of excitement.”

Now granting the validity of this opinion, still there is a residual
phenomenon to account for, viz. the reason why substances of dif-
ferent kinds assume opposite electrical states when brought into con-
tact. Judging from analogy, we think a reasonable explanation can
be found by supposing particles of different substances to possess
different capacities for electricity, or a different specific electricity.
We know that bodies have different capacities for heat,—thus, we
know that mercury at the temperature of 212° contains a very dif-
ferent quantity of heat to that of an equal weight of water at a simi-
lar temperature,—and it is a legitimate inference, in perfect confor-
mity with the laws of induction, to assume that bodies also have dif-
ferent specific electricities; that two substances of different kinds,
placed under such circumstances that each has an equal opportunity
of parting with or retaining its electricity, will contain, when an equi-
librium is established between each of them and the atmosphere or

Intelligence and Miscellaneous Articles. 171

surrounding objects, and consequently between each other also, dif-
ferent quantities of electricity. Now we know that if two bodies of
a similar nature (say two pith balls) contain dissimilar quantities of
electricity, they will attract each other, the one containing the great-
est charge being positive with regard to the other; and we may infer
from this, if two bodies of a different kind,such as potassium and oxy-
gen, assume, the one a positive and the other a negative electricity,
when brought into contact (an admission necessary for the support
of Sir H. Davy’s theory), that the potassium, which evinces a positive
energy, contains more electricity than the oxygen, which becomes ne-
gative. If so, if this obtains when both are placed under similar cir-
cumstances,—both at an equilibrium of electricity, it follows in-
evitably that they must have different capacities for electricity; so
that the inference of different capacities for electricity is, we think, to
the fullas clear as the inference of the attractive force or affinity being
dependent onelectricity. This theory will account for some bodies
having a disposition to unite, others evincing no such disposition at
all,&c.: thus the two pith balls oppositely electrified, by the one con-
taining an excess and the other a deficiency or at least a smaller
quantity than the other, stand in the relation of two dissimilar sub-
stances having different specific electricities, and consequently con-
taining different quantities; and in like manner they possess an at-
traction for each other, but no sooner do they touch than an equili-
brium of electricity is established, and they are no longer in the same
relative condition,inas much as each now contains the same quantity
of electricity ; byreason of their specific electricities being equal, they
therefore no longer have any attraction for each other. This is very
different with regard to oxygen and potassium; these bodies when
brought into contact powerfully attract each other, and then still
maintain each its peculiar specific electricity, and consequently
their mutual attraction continues: hence the reason why the elements
of a compound retain their respective states of excitement, upon
which the very existence of the compound depends. According to
this view, substances which in their natural condition not only have
no attraction or affinity for each other, but repel each other, (if any
such actually exist,) should be considered as possessing like specific
electricities; and the disparity in the force of attraction should be
considered to depend on the disparity in the capacity for electricity.
To illustrate this by an example, we should consider that the disparity
between the specific electricity of oxygen and potassium is so great
that they unite the moment they are brought within reach of each
other;—then the disparity in the specific electricities of oxygen and
hydrogen we should consider as less than that between the two for-
mer, and therefore they do not unite when simply brought into con-
tact; but they do not repel each other, therefore they do not possess
equal specific electricities ; so that by making the disparity more ap-
parent, (which is done by giving each a higher charge, as when an
electric spark is passed through them,) they do attract each other, and
unite—once united, their natural difference in electrical capacity
suffices to huld them in union, Just so the two pith balls do not re-

T2

172 Intelligence and Miscellaneous Articles.

pel each other, do not evince the similarity of their specific electri-
cities, until] made more apparent by their possessing a higher charge
than surrounding objects ; and when they have parted with their su-
perabundance and attained an equilibrium with surrounding objects
the repulsion ceases: so in the other case would the attraction cease,
but the elements of the compound cannot lose their relative super-
abundance and deficiency :—so that we should consider that the dif-
ficulty of union of substances and the quantity of additional electrical
excitement required to make them combine, is a measure of the dif-
ference of their specific electricities. This theory may be applied also
to account for a substance evincing one kind of electric energy when
about to combine with one substance, and the opposite state when
about to combine with another; thus, according to this view, sulphur
possesses a greater specific electricity than oxygen and a less specific
electricity than mercury, and is consequently positive with regard to
oxygen and negative in relation to mercury.

26, Woburn Place, London, 2
August.17,/1835. Epwarp B. Watrorp.

NOTE ON MR. CHALLIS’S PAPER ON CAPILLARY ATTRACTION.

The following editorial note was written with the intention of an-
nexing it to that passage of Mr. Challis’s paper inserted in the present
number, p. 94, in which mercury is excluded from part of the investiga-
tion, as being incapable of adhering, like other fluids, to solid bodies.

We apprehend that it will eventually be found necessary to extend
this investigation to the case of mercury, which is as capable of ad-
hering to metals, (to platinum, for example,) as water and oil are of
adhering to other solids, metals being in fact moistened by mercury.
See Philosophical Magazine, First Series, vol. xviii. p. 110, note; and
Quarterly Journal of Science, vol. xx. p.82 et seqg.; vol. xxi, p.231
et seg. Inthe note in Phil. Mag. here referred to, the perfect con-
tact of fluids with the solids which they are capable of wetting ts at-
tributed to their mutual chemical action; and Mr. Daniell, in the
Quarterly Journal, loc. cit., also ascribes it to the ‘‘ affinity” of the
fluid for the solid; but Mr. Faraday appears to refer it to an inter-
mediate species of attraction, ‘‘ in part elective, partaking in its cha-
racters both of the attraction of aggregation and chemical affinity :’’
see his Exp. Res. in Electricity, Sixth Series, par.620, 624, in Phil.
Trans. for 1834, pp. 66, 67. It is even probable that the results ob-
tained by Link, as described in the last page of Mr. Challis’s paper,
may be explained in a similar manner, for the order of the heights to
which the fluids mentioned ascended is almost precisely that of what
we should conceive, a priori, would be the relative degrees of an ap-
proximate chemical attraction of the fluids for glass or its elements.
The mathematical investigation, we may suggest to Mr. Challis, of
the entire series of facts related by Mr. Faraday in the memoir alluded
to, and which are ascribed by that philosopher to the mediate at-
traction in question, could not fail materially to contribute to the
elucidation of this obscure though very important and interesting
subject —E. W. B.

wi

perturbations, &c.

Intelligence and Miscellaneous Articles. 173

M. BREITHAUPT’S MINERALOGY.

In No. 27 of this work we noticed two varieties of wavellite from
Frankenberg, and stated, upon what we now find to have been in-
accurate information, that they had been named by M. Breithaupt
Peganit and Pegmatit. This latter name should have been Sérigisan.
We have since had an opportunity of examining another of this gen-
tleman’s new minerals, his Arsenic Glance, which appears to con-
sist of native arsenic and galena in distinct and unmixed layers.
A specimen, said to be his Batrachite, has also been brought to us ;
but it seems to be only an amorphous mass of a grayish rock, without
any definite mineralogical character ; and possibly many more equally
good species might be afforded from the same locality.

We cannot but regret to see an already overloaded nomenclature
thus encumbered with new names representing nothing that can ever

‘yank as distinct minerals. The alumocalcite of this author is another

instance of considering accidental varieties of known minerals as new
species; and the specimen in situ of his erlanite, from which the
fragment that has been analysed was taken, is said to be some miles
in extent, and at least 100 fathoms in thickness. ‘The Andes might
afford a copious harvest of such simple minerals as this.—EbirT.

HALLEY’S COMET.

This interesting body has been twice seen since its perihelion pas-
sage by the Rev. R. Dawes, of Ormskirk, on the 16th and 19th in-
stant. On the 16th its place was noted, and found to be, January
15,785, 1836, Greenwich, mean time, R.A, comet 15h. 59 min. 46: sec.
south declination 27 deg. 22 min. 30sec. These values will require
some further correction, and the declination is considered to be an
approximation merely, On the 19th the haze only gave time for a
casual glimpse. As the comet is said by Mr. Dawes to be “‘ exceed-
ingly faint”, itis hopeless to look for it with any telescope which does
not considerably exceed his in power—that is, a very excellent five-
feet telescope, made and mounted by Dollond. Mr. Dawes is acknow-
ledged to be one of the most skilful and delicate measurers of minute

‘celestial phenomena in this country, and has contributed several

valued memoirs to the Royal Astronomical Society. By interpolat-
ing from Lieutenant Stratford's admirable ephemeris of Hatiey’s
comet, for the moment of Mr. Dawes’s observation, the place is found
to be R.A. 15h. 59 min. 43°5 sec. south declination, 27 deg. 22 min.
42 sec., a very near coincidence, especially when it is remembered
that the ephemeris only pretends to: be approximate, is founded on
unreduced observations, and is not as yet corrected for planetary

ON SESQUISULPHATE OF MANGANESE. BY DR. THOMSON,

When neutral solutions of sulphate of zinc and chloride of manga-
nese are mixed together, no sensible change takes place. But if tne
mixture be concentrated, it gradually deposits yellowish white co-

174 Intelligence and Miscellaneous Articles.

loured crusts, which constitute a hitherto undescribed salt of manga-
nese.

This salt dissolves readily in water, but I could not succeed in ob-
taining it in crystals. Its taste is sweetish and astringent, and
slightly acid.

16:26 grs. of it, rendered as dry as possible by pressure between
the folds of blotting-paper, and subsequent exposure to a gentle heat,
were dissolved in water, and mixed with a great excess of carbonate
of ammonia. The mixture was left for twenty-four hours, and during
that time was frequently agitated. It was then thrown on a filter, to
collect the white precipitate which had fallen. This precipitate became
brown by exposure to the air, and by ignition acquired a reddish tint.
In this state it was red oxide of manganese. It weighed 5-78 grs.
= 5°38 grs. of protoxide of manganese.

The ammoniacal liquid which passed through the filter being eva-
porated to dryness, and the residue redissolved in water, left a small
quantity of matter, which became red by ignition, and was also red
oxide of manganese. It weighed 0-07 gr. = 0°065 gr. of protoxide.
So that the whole protoxide of manganese contained in 16°26 grs. of
the salt amounts to 5°445 grs.

The liquid thus freed from base was treated with nitrate of silver.
The chloride of silver obtained, weighed, after ignition, 0°5 gr. =
0-12 gr. of chlorine.

The excess of silver being removed by the addition of a little com-
mon salt, the liquid was precipitated by muriate of barytes. The sul-
phate of barytes obtained being collected, washed, and ignited, weighed
24:06 grs. = 8°5 grs. sulphuric acid.

What is wanting to complete the 16°26 grs. must be water. For
on other constituent could be obtained.

Thus it appears that the salt is composed of,

Sulphuric acid .)..:.2 sai). mi 8°5

Chlorine iyisinst.;ck Seuisia pees 0°12
Protoxide of manganese..... 9°445

Water jac fi ated tte Pen 2°195— 16:26

The chlorine was doubtless combined with manganese, probably in
the state of tris-chloride. We must, therefore, subtract 0:36 from the
protoxide of manganese. The remainder, 5-085, is the quantity of
manganese in combination with the sulphuric acid. Now, 5'1 is
8:5 as 4:5 to 7'5. So that the salt is composed very nearly of

14 atom sulphuric acid ...... 7°95
] atom protoxide of manganese 4°5
2-atOMS, WALER «5 a\e-sie -'s)s 2 01 2-25—14°25

The water was rather less than two atoms. Probably a little had
been driven off in the attempt to dry the salt by heat.

To what the yellow colour is owing which this salt possesses I do
not know. The solution of it in water is colourless, so that none of
the manganese can be in a state of red oxide. I could detect no
oxide of zinc in the oxide of manganese, and none could be extracted
by digesting the newly precipitated oxide in caustic potash.

Records of Science, vol. ii. p. 369.

——EE~EEoo—_ eee

-

Meteorological Observations. 175

ON CRYSTALLIZED OXIDE OF CHROMIUM. BY M. F. WOHLER.

When perchoride of chromium is passed in the state of vapour,
through a glass tube heated to redness, it is decomposed into oxide
of chromium, which remains in the tube in a crystalline form, and a
mixture of chlorine and oxygen gases. The crystals of oxide of
chromium thus obtained are black, of a metallic lustre, hard, well
defined, and brilliant, possessing exactly the same form as the native
peroxide of iron (_fer oligiste), which confirms the isomorphism before
recognised in these two oxides. The exterior characters of these
oxides, when crystallized, are precisely similar ; the specific gravity
of this oxide of chromium is 5°21, nearly approaching to that of
oxide of iron; but whilst the latter gives a red powder, that of the
former is green, like the common oxide of chromium. These cry-
tals are as hard as corundum, which, next to the diamond, ranks as
the hardest known body.—Journal de Pharmacie, Juin 1835.

NEW SCIENTIFIC BOOKS.

A Manual of British Vertebrate Animals. By the Rev. Leonard
Jenyns, M.A., F.L.S., &c.

An Elementary Treatise on the Computation of Eclipses and Oc-
cultations. By J.W. Lubbock, Esq., F.R.S., &c.

Notices of Communications to the British Association for the Ad-
vancement of Science ; at Dublin, in August 1835.

Geology of Yorkshire, Vol. Il. By Prof. Phillips.

Philosophical Transactions, Part IJ. 1835.

Remarks occasioned by Lord Brougham’s Paley’s Natural Theology
illustrated. By Thomas Martin.

METEOROLOGICAL OBSERVATIONS FOR DECEMBER 1835.

REMARKS.

Chiswick.— December 1. Clear and fine: cloudy and windy at night.
2. Very fine. 3.Cloudy. 4, 5.Fine. 6. Frosty and foggy. 7. Foggy.
8.Hazy:rain. 9.Cloudy andcold. 10. Slightsnow. 11—13. Sharp
frost, 14,15. Hazy. 16,17. Dense fog. 18. Clear: hail shower at noon.
19, Cloudy and cold. 20. Slight snow. 21. Overcast : clear and cold.
22. Sharp frost : foggy. 23—26. Frosty and foggy. 27.Cloudy. 28. Fine.
29. Overcast. 30. Fine. 31. Frosty with dense fog. The quantity of
rain in this month amounted only to a quarter of an inch.

P.S. Observing the discrepancy apparent in your last Journal between
the results of observations at the Apartments of the Royal Scciety and at
this Garden, I intended to have sent some account of the instruments used
here, and their situation. Such will be necessary ; but as some investiga-
tions are being made on the subject, I thought it better to defer it till next
Number. I shall therefore only remark that the thermometers here, in-
dicating the max. and min. of temperature, are in an open space, unaffected
by radiation from buildings—a circumstance which must have a very great
influence on those used for the same purposes at Somerset House.—
R. Tuomrson.

Boston.—December 1, 2. Fine. 3. Cloudy. 4,5.Fine. 6, Cloudy.
7,8. Foggy. 9. Cloudy: rain early a.m. 10 11. Fine. 12. Cloudy.
13.Fine. 14,15. Cloudy. 16.Fine. 17. Foggy. 18. Fine. 19. Snow:
<— night with snow. 20,21.Cloudy, 22—26,Fine. 27—s0. Cloudy.
21. Fine.

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THE
* LONDON ann EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]
MARCH 1836.

XXXII. On the general Magnetic Relations and Characters
of the Metals. By Micuae. Farapay, D.C.L. F.R.S., &c.*

GENERAL views have long since led me to an opinion,
which is probably also entertained by others, though I
do not remember to have met with it, that a// the metals are
magnetic in the same manner as iron, though not at common
temperatures or under ordinary circumstancest. I do not
refer to a feeble magnetism, uncertain in its existence and
source, but to a distinct and decided power, such as that pos-
sessed by iron and nickel; and my impression has been that
there was a certain temperature for each body, (well known
in the case of iron,) beneath which it was magnetic, but above
which it lost all power ; and that, further, there was some rela-
tion between this point of temperature, and the intensity of
magnetic force which the body when reduced beneath it could
acquire. In this view iron and nickel were not considered as
exceptions from the metals generally with regard to mag-
netism, any more than mercury could be considered as an ex-
ception from this class of bodies as to liquefaction.
I took occasion during the very cold weather of December
last, to make some experiments on this point. Pieces of va-
rious metals in their pure state were supported at the ends of

* Communicated by the Author.

+ It may be proper to remark that the observations made in par, 255
of my “ Experimental Researches,” have reference only to the three classes
of bodies there defined as existing at ordinary temperatures.

t Encyclop. Metrop., ‘ Mixed Sciences,’ vol. i. p. 761.

Third Series. Vol. 8. No. 46. March 1836. U

178 Mr. Faraday on the general Magnetic Relations

fine platinum wires, and then cooled to a very low degree by the
evaporation of sulphurous acid. They were then brought
close to one end of one of the needles of a delicate astatic ar-
rangement, and the magnetic state judged of by the absence or
presence of attractive ferces. ‘The whole apparatus was in an
atmosphere of about 25° Fahr.: the pieces of metal when
tried were always far below the freezing-point of mercury, and
as judged, generally at from 60° to 70° Fahr. below zero.
The metals tried were,

Arsenic, Lead,
Antimony, Mercury,
Bismuth, Palladium,
Cadmium, Platinum,
Cobalt, Silver,
Chromium, Tin,
Copper, Zinc,
Gold,

and also Plumbago; but in none of these cases could I obtain
the least indication of magnetism.
Cobalt and chromium are said to be both magnetic metals.
I cannot find that either of them is so, in its pure state, at
any temperatures. When the property was present in speci-
mens supposed to be pure, I have traced it to iron or nickel.
The step which we can make downwards in temperature
is, however, so small as compared to the changes we can pro-
duce in the opposite direction, that negative results of the
kind here stated could scarcely be allowed to have much weight
in deciding the question under examination, although, unfor-
tunately, they cut off all but two metals from actual compari-
son. Still, as the only experimental course left open, I pro-
ceeded to compare, roughly, iron and nickel with respect to
the points of temperature at which they ceased to be magnetic.
In this respect iron is well known*. It loses all magnetic pro-
perties at an orange heat, and is then, to a magnet, just like a
piece of copper, silver, or any other unmagnetic metal. It does
not intercept the magnetic influence between a magnet and
a piece of cold iron or a needle. If moved across magnetic
curves, a magneto-electric current is produced within it exactly
as in other cases. The point at which iron loses and gains
its magnetic force appears to be very definite, for the power
comes on suddenly and fully in small masses by a’small di-
minution of temperature; and as suddenly disappears upon
a small elevation, at that degree.
With nickel I found, as I expected, that the point at which
it lost its magnetic relations was very much lower than with

* See Barlow on the Magnetic Condition of Hot Iron. Phil. Trans.
1822, p. 117, &c.

and Characters of the Metals. 179

iron, but equally defined and distinct. If heated and then
cooled, it remained unmagnetic long after it had fallen below
a heat visible in the dark: and, in fact, almond oil can bear
and communicate that temperature which can render nickel
indifferent to a magnet. By a few experiments with the ther-
mometer it appeared that the demagnetizing temperature for
nickel is about 630° or 640°. A slight change about this
point would either give or take away the full magnetic power
of the metal.

Thus the experiments, as far as they go, justify the opinion
advanced at the commencement of this paper, that all metals
have similar magnetic relations, but that there is a certain
temperature for each beneath which it is magnetic in the man-
ner of iron or nickel, and above which it cannot exhibit this
property. This magnetic capability, like volatility or fusibi-
lity, must depend upon some peculiar relation or condition of
the particles of the body; and the striking difference between
the necessary temperatures for iron and nickel appears to me
to render it far more philosophical to allow that magnetic
capability is a general property of ail metals, a certain tem-
perature being the essential condition for the development of
this state, than to suppose that iron and nickel possess a
physical property which is denied to all the other substances
of the class. .

An opinion has been entertained with regard to iron, that
the heat which takes away its magnetic property acts somehow
within it and amongst its electrical currents (upon which the
magnetism is considered as depending) as flame and heat of
a similar intensity act upon conductors charged with ordinary
electricity. The difference of temperature necessary for iron
and nickel is against this opinion, and the view I take of the
whole is still more strongly opposed to it.

The close relation of electric and magnetic phenomena led
me to think it probable, that the sudden change of condition
with respect to the magnetism of iron and nickel at certain
temperatures, might also affect, in some degree, their con-
ducting power for electricity in its ordinary form; but I could
not, in such trials as I made, discover this to be the case with
iron. At the same time, although sufficiently exact to indicate
a great change in conduction, they were not delicate enough
to render evident any small change; which yet, if it occurred,
might be of great importance in iilustrating the peculiarity of
magnetic action under these circumstances, and might even
elucidate its general nature.

Before concluding this short paper, I may describe a few

results of magnetic action, which, though not directly con<
U2

180 On the Magnetic Relations of the Metals.

cerned in the argument above, are connected generally with
the subject*. Wishing to know what relation that temperature
which could take from a magnet its power over soft iron, had
to that which could take from soft iron or steel its power rela-
tive to a magnet, I gradually raised the temperature of a mag-
net, and found that when scarcely at the boiling-point of al-
mond oil it lost its polarity rather suddenly, and then acted
with a magnet as cold soft iron: it required to be raised to a
full orange heat before it lost its power as softiron. Hence
the force of the steel to retain that condition of its particles
which renders it a permanent magnet, gives way to heat at a
far lower temperature than that which is necessary to prevent
its particles assuming the same state by the inductive action of
a neighbouring magnet. Hence at one temperature its par-
ticles can of themselves retain a permanent state; whilst at a
higher temperature that state, though it can be indeed from
without, will continue only as long as “the inductive action lasts;
and at a still higher temperature all capability of assuming
this condition is lost.

The temperature at which polarity was destroyed appeared
to vary with the hardness and condition of the steel.

Fragments of loadstone of very high power were then ex-
perimented with. ‘These preserved their polarity at higher
temperatures than the steel magnet; the heat of boiling oil was
not sufficient to injure it. Just below visible ignition in thedark
they lost their polarity, but from that to a temperature a little
higher, being very dull ignition, they acted as soft ron would
do, and then suddenly lost that power also. ‘Thus the load-
stone retained its polarity longer than the steel magnet, but
lost its capability of becoming a magnet by induction much
sooner. When magnetic polarity was given to it by contact
with amagnet, it retained this power up to the same degree
of temperature as that at which it held its first and natural
magnetism.

A very ingenious magnetizing process, in which electro-mag-
mets and a ‘high temperature are used, has been proposed
lately by M. Aimé+. Iam not acquainted with the actual
results of this process, but it would appear probable that the
temperature which decides the existence of the polarity, and
above which all seems at liberty in the bar, is that required.
Hence probably it will be found that a white heat is not more
advantageous in the process than a temperature just above or
about that of boiling oil; whilst the latter would be much

* See on this subject, Christie on Effects of Temperature, &c. Phil.

Trans. 1825, p. 62, &c.
+ Annales de Chimie et de Physique, tome lvii. p. 442.

Effects of Earthquake Waves on the Coasts of the Pacific. 181

more convenient in practice. The only theoretical reason
for commencing at high temperatures would be to include
both the hardening and the polarizing degrees in the same
process; but it appears doubtful whether these are so con-
nected as to give any advantage in practice, however advan-
tageous it may be to commence the process above the depo-
larizing temperature.

Royal Institution, Jan. 27, 1836.

XXXIII. On the Effects of the Earthquake Waves on the
Coasts of the Pacific. By WoovstnE Panisu, Esq., F.2.S.,
Secretary to the Geological Society.*

T one of our meetings last season, in a discussion which
arose out of the discovery of recent shells and other ma-
rine deposits on several parts of the coasts of Chile and Peru
above the present level of the sea, I ventured to throw out the
opinion that a great part of those appearances might, perhaps,
be referred to violent upheavings of the sea under the influence
of earthquakes. I had then only in my recollection the earth-
quake waves which burst over Scylla and Lisbon in Europe,
and Callao in America; but upon looking into the early
writers upon the countries bordering on the Pacific, I have
found so many recorded instances of these disruptions of the
great ocean, and in some cases attended with such remarkable
effects, that I have thought it might interest the Society to
have them collectively before it, particularly upon any new
discussion of such phenomena as first gave rise to my obser-
vations upon the subject.
Under that impression I have put them together in this

paper.

Historical Notices of the Effects of the Earthquake Waves on
the Coasts of Chile and Peru.

Acosta in his Historia Natural y Moral de las Indias, writ-
ten in 1590, gives us a chapter upon the earthquakes of his
time, from which the following is a translation: he says, ** On
the coast of Chile, do not remember precisely the year,
there took place a very terrible earthquake, which overthrew
whole mountains, stopping up with them the courses of rivers
and turning them into lakes, destroying towns, and a vast
number of people.” Jt caused the sea to rise out of its bed
some leagues, leaving ships dry far inland.

* Read before the Geological Society Dec, 2, 1835 ; and now communi-
cated by the Author.

182. Mr. Woodbine Parish on the Effects of the

A few years afterwards (in 1582) Arequipa was destroyed
by an earthquake.

In 1586, on the 9th of July, happened an earthquake at
Lima which, according to the Viceroy’s account of it, was
felt for 170 leagues along the coast. Amongst other calami-
tous consequences of it, Acosta mentions that ‘ the sea then
was upheaved as on the former occasion on the coast of Chile,
rising afler the shock of the earthquake mightily out of its bed,
and bursting over the shore nearly two leagues inland, over-
whelming all that shore, and leaving the shrubs and trees as it
were swimming in the waters.”

Frezier in the account of his voyage to the South Seas (in
1712, 1713, 1714,) speaks of an earthquake wave which de-
stroyed the town of Arica in 1605. He says, * On the 26th
of November 1605, the sea, being agitated by an earthquake,
suddenly flooded and bore down the greatest part of it; the
ruins of the streets are to be seen to this day,” &c.

The next account we have of a similar event is from Ulloa’s
Voyage to South America. In enumerating the earthquakes
experienced at Lima, he writes: “ One of the most dreadful
of which we have any account was that of the 20th of Octo-
ber 1687. It began at four in the morning, with the destruc-
tion of several public edifices and houses, whereby great num-
bers of persons perished ; but this was little more than a pre-
sage of what was to follow, &c. &c.

“¢ During the second concussion, the sea retired considerably
JSrom its bounds, and returning in mountainous waves, totally
overwhelmed Callao and the neighbouring parts, together with
the miserable inhabitants.”

Our own countryman Lionel Wafer, who was in those seas
at the time, says, “* When we were in the latitude of 12 de-
grees 30! south, and about 150 leagues from the coast, our
ship and bark felt a terrible shock, which put our men into
much consternation, so that they could hardly tell where they
were, or what to think, but every one began to prepare for
death ; and, indeed, the shock was so sudden and violent that
we took it for granted the ship had struck upon a rock: but
when the amazement was a little over, we cast the lead and
sounded, but found no ground, so that after consultation we
concluded it must certainly be some earthquake. The sud-
denness of the shock made the guns of the ship leap in their
carriages, and several of the men were shaken out of their
hammocks: Capt. Davis, who lay with his head over a gun,
was thrown out of his cabin. The sea, which ordinarily looks
green, seemed then of a whitish colour, and the water which
we took up in our buckets for the ship’s use we found to be
mixed with sand: this at first made us think there was some

Earthquake Waves on the Coasts of the Pacific. 183

spit cf land; but when we had sounded, it confirmed our opi-
nion of the earthquake...... Afterwards we heard the news that
at that very time there was an earthquake at Callao, and the
sea ebbed so far from the shore that on a sudden there was no
water to be seen; and that after it had been away some time it
returned in rolling mountains of water, which carried the ships
in the road of Callao a league up into the country, overflowing
the city of Callao, together with the port, and drowned man and
beast for 50 leagues along the shore,” &c. Sc.

Wafer describes the effects of a similar catastrophe at Santa,
about three degrees to the north of Callao, which he wit-
nessed. He says, “‘ On landing I went up to the town, which
was three miles or thereabouts from the sea. In our way
to the town we cros$ed a small hill, and in a valley between
the hill and the town we saw three small ships, of about 60
or 100 tons each, lodged there and very ruinous: it caused in
us great admiration, and we were puzzled to think how those
ships could come there; but proceeding towards the town we
saw an Indian, whom we called, and he at the first motion came
tous. We asked him several questions, and among the rest
how those ships came there. He told us that about nine
years before (1678) those three ships were riding at anchor in
the bay, which is an open place about five or six leagues from
point to point; and that an earthquake came and carried the
water out of sight, which staid away twenty-four hours, and then
came in again tumbling and rolling with such violence that it
carried these ships over the town which then stood on the hill
which we came over, and lodged them there, and that it de-
stroyed the country for a considerable way along the coast.
This account when we came to the town was confirmed to us
by the priest and many other inhabitants of the town.

Ulloa speaks of great earthquakes at Lima in the years
1697, 1699, 1716, 1725, 1732, 1734, and 1745, but does not
give us the details of them. He gives a more particular ac-
count of that one, the most dreadful of all up to the time he
wrote, which took place in 1746. But of this I shall rather
give an extract from the narrative published at the time by
authority of the Viceroy.

After stating the direful effects of this earthquake at Lima,
that account proceeds thus:

“Yet at least the remains of what Lima was are still ex-
isting; not so fares it with the garrison and port of Callao,
where the very objects of the misfortune are quite vanished
out of sight: this doubles the concern and anguish of the mind,
which shudders at the contemplation of the dreadful calamity.
Not the least sign of its former figure does now appear: on
the contrary, vast heaps of sand and gravel occupying the spoy

184 | Mr. Woodbine Parish on the Effects of the

of its former position, it is at present become a spacious strand,
extending along that coast.. Some few towers, indeed, and the
strength of its walls for a time endured the whole force of
the earthquake, and resisted the violence of its shocks; but
scarcely had its poor inhabitants begun to recover from the
horror of the first fright which the dreadful ruin and devasta-
tion had occasioned there, (and how great that was is not to be
known,) when suddenly the sea began to swell, either through
the impulsive force which the earth by its violent agitation
impressed upon it,—and thereby keeping up for a time, in one
vast body, mountains of water,—or by what other means na-
tural philosophers may please to assign, which on these occa-
sions are the causes of its elevation—and swelling rose to such
a prodigious degree, and with so mighty a compression, that
on falling from the height it had attained, (although Callao
stood above it on an eminence which, however imperceivable,
yet continues still increasing all the way to Lima,) it rushed
furiously forward, and overflowed with so vast a deluge of water
its ancient bounds, that foundering the greater part of the ships
which were at anchor in the port, and elevating the rest of
them above the height of the walls and towers, drove them
on and left them on dry ground, far beyond the town; at the
same time it tore up from the foundation everything that was
in it of houses and buildings, excepting only the two great
gates, and here and there some small fragment of the walls
themselves, which as registers of the calamity are still to be
seen among the ruins and the waters, a dreadful monument
of what they were.

‘In this raging flood were drowned all the inhabitants of
the place, who at that time might amount to near 5000 per-
sons, of all ages, sexes, and conditions, according to the most
exact calculation that can be made,” &c. &c.

** There were twenty-three ships, great and small, at anchor
in the port at the time of the earthquake: and of these, as has
been mentioned before, some were stranded, being four in
number, viz. the § San Firmin’, man of war, which was found
in the low ground of the upper Chacara, the part opposite to
the place where she rode at anchor, and near her the ‘St. An-
tonio,’ belonging to Don Thomas Costa, a new ship just ar-
rived from Guayaquil: the vessel of Don Adirar Corsi rested
on the spot where before stood the hospital of St. John, and
the ship * Succour’ of Don Juan Baquixano, which had just
arrived that very evening with a cargo from Chile, was thrown
up towards the mountains, both one and the other of them at

reat distances from the sea; and all the rest were foundered.”

Ulloa adds, that “this terrible inundation extended to
other ports of the coast, as Cavallos and Guanape, and the

of the Earthquake Waves on the Coasts of the Pacific. 185

towns of Chancay, Guara, and the valleys Della Barranca,
Sape, and Patevilca underwent the same fate as the city of
Lima.”

Five years afterwards, in 1751, on the 26th of May, the
city of Conception, called by the Indians Penco, on the coast
of Chile, was totally destroyed by an inundation of the sea;
in consequence of which the inhabitants removed to some di-
stance from it, and rebuilt their city on the spot where it now
stands.

In Molina’s account of Chile, speaking of this event, he
mentions that the city was agazm inundated, alluding to a si-
milar catastrophe which had befallen it some years before, in
1730: to which Ulloa has more particularly alluded. He
says, on that occasion (in 1730) * the sea at first retired a
considerable way; but soon it rose so greatly that, passing its
ordinary bounds, it inundated the city (Penco) and the country
about it, obliging all the inhabitants to seek safety on the neigh-
bouring hills.”

The earthquake wave which overwhelmed Conception in
1751, was equally felt at the island of Juan Fernandez. I have
a manuscript report of the Viceroy of Peru (lately published
in the Journal of the Royal Geographical Society), wherein
it is stated that “the first colony of the Spaniards had not
long been settled there when it was almost totally destroyed
by the same dreadful earthquake which, in the year 1751,
overthrew the city of Conception in Chile: with the earth-
quake the sea rose and overwhelmed the houses, most of which
had unfortunately been built along the shore. Thirty-five
persons perished from this calamitous event, and amongst
them the governor with his wife and children.”

It is unnecessary for me to repeat, that in the great earth-
quake of 1822, on which there has been so much discussion,
the sea is said to have been agitated in an extraordinary de-
gree. Mrs. Graham, in her Journal, tells us that “ on the
night of the 19th of November, during the first great shock,
the sea in Valparaiso Bay rose suddenly, and as suddenly re-
tired, in an extraordinary manner, and in about a quarter of
an hour seemed to have recovered its equilibrium.”

She further mentions having heard from the officers on
board Lord Cochrane’s ship, that when His Lordship “ and
others threw themselves immediately into a boat to go to the
assistance, if help were still possible, of the sufterers, the
rushing wave landed them higher than any boat had been be-
Sore, and they then saw it retire frightfully, and leave many of
the launches and other small vessels dry.”

I had written so far when the accounts reached this coun-

Third Series. Vol. 8. No. 46. March 1836. x

186 Prof. Powell on the Transmission of Radiant Heat.

try of the dreadful earthquake which, on the 20th of February
last, again utterly destroyed the city of Conception, with its
sea-port at Talcahuano, and all the towns of Chile between
the parallels of 35° and 38° south latitude.

The details which have as yet reached us afford another
remarkable evidence of the direful and irresistible effects of
the earthquake wave. In the Bay of Talcahuano the sea is
said to have risen three times, overwhelming the town, and
sweeping away its ruins with such a rush and whirl of waters
as, to quote one account, it is more easy to imagine than
describe, and carrying some of the ships far up upon the
shore.

The circumstance of a vessel, ‘the Glemalier,” having ex-
perienced a violent shock when at a distance of ninety-five
miles from the coast, which stopped her course and induced
the master to believe she had struck the ground, coincides
remarkably with old Wafer’s account of what happened to
himself off the coast of Peru during the earthquake of 1687,
and is of value, in as much as it corroborates his testimony to
a fact which before seemed hardly credible*.

Such is the list with which history furnishes us of these
terrific inundations. Fearful as it is, if we bear in mind how
recently we have become aware even of the existence of those
coasts, and how extremely imperfect is our knowledge of
them at all, we shall have no difficulty in believing that it
comprises but a very small portion, indeed, ofa series of events
which, in a very short period of time, geologically speaking,
must have left indelible marks of their tremendous agency,
attesting but too well the calamitous visitations to which the
inhabitants of those shores are subject.

XXXIV. Note on the Transmission of Radiant Heat. By the
Rev. BavEN Powet1, M.A., F.R.S., Savilian Professor of
Geometry, Oxford.t

FEW scientific discussions are more unsatisfactory than

those in which writers endeavour to point out, or explain,
misconceptions of each other’s meaning. In reference to one
or two remarks somewhat of this nature made in the course
of papers in recent Numbers of this Journal, on the subject of
radiant heat, I will merely state, in the fewest possible words,

* We believe that several if not many other instances of the same fact
have been recorded, chiefly in the older accounts and collections respect-
ing earthquakes.—Eprr.

+ Communicated by the Author.

Mr. Atkinson on Sir G. S. Mackenzie’s Remarks. 187

distinctly what my meaning was, and there leave the ques-
tion.

The result which I obtained in 1825, and which M. Mel-
loni has so fully verified, was this: The effect from a lumin-
ous hot body, without any screen, upon a black and a white
surface respectively, was observed to be in a certain ratio;
the same effects when a transparent screen was interposed
were in a different and greater ratio. M. Melloni’s theory is,
that this new and different relation to suzfaces is communi-
cated to the rays by, and in, the act of passing through the
screen; so at least I understand it. Now ¢his is what I objected
to as a very singular theory, discordant (as I conceive) with
allanalogy, and needless, in as much as the effect is explained
by the much simpler supposition, that there are two distinct
sorts of heat emanating at the same time from the luminous
body, distinct in their relations to surfaces as well as to screens.

It was to this single point alone that my remarks applied.
With the other valuable results of M. Melloni I am not now
concerned. I will merely add, in the present unformed state
of this entire branch of our knowledge it seems hardly sate
to adopt any theory, except as a mere conjectural guide.
But I have the greatest hopes that before long we shall be in
a condition to advance to some satisfactory general principles,
when I find such an instrument as M. Melloni’s in active
employment in the hands of such able and zealous experi-
menters as are now engaged with it in Edinburgh and

Dublin.

XXXV. On Sir G.S. Mackenzie’s Remarks on certain Points
in Meteorology, &c., inserted in Lond. and Edinb. Phil. Mag.
for November 1835. By Josepu Arxinson, Esq., Secretary
to the Carlisle Literary and Philosophical Society.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
HAVE been induced by Sir G. S. Mackenzie’s remarks

on the equinoctial gales, contained in your Magazine for
November last, to look for a corroboration of his supposition
that the equinoctial gales have of late come from the eastward,
but I cannot find that such has been the case here. ‘The si-
tuation of Coul is most probably the cause of the easterly
winds being so prevalent there. On the 22nd of September,
which is the day mentioned as the one on which he wrote his
letter, while an easterly wind was blowing, I find a southerly
wind noted in my journal. ‘This of itself is enough to show

X 2

188 Mr. Atkinson’s Meteorological Remarks.

that locality has a great deal to do with the kind of winds
prevalent at each place. On the 30th of September, in the pre-
sent year, the easterly winds began to below here, and con-
tinued without intermission till the 8th of October; and from
the 26th of August to the 2nd of September, easterly winds
also prevailed: but while these winds were altogether light,
scarcely approaching to the character of a breeze, the west-
erly winds, which prevailed from the 2nd to the 29th of Sep-
tember, were very strong, and on several days, especially on
the 28th of September, might be called gales.

Sir G. Mackenzie’s remarks as to the easterly winds having
lately come much charged with moisture will, I find on re-
ference to my journal, apply to Carlisle as well as Coul; for
on looking back at those days on which easterly winds have
prevailed during the past year, I finda great proportion noted
as drizzly or showery.

I have also remarked that easterly winds have become
much more prevalent here of late years than was wont to be the
case, while the south-westerly have of late been decreasing in
number. Whether this excess of easterly winds is likely to
continue, or will only be for a year or two, it is of course al-
most impossible to tell, but I am inclined to think it only
temporary. It is rather remarkable that in the month of Fe-
bruary last (1835) the wind never blew from an easterly
point for even a quarter of aday. The month of May seems
to be the one in which easterly winds have most prevailed
here for the last two years.

The observations which are made at the Apartments of the
Royal Society in London must surely be very loosely taken,
for I often find the height of the thermometer as noted at
3P.M., to exceed the maximum! This most probably arises
from the use of two thermometers, having either different
scales, or else hanging in different positions. This cireum-
stance, added to the evidently too small quantity of rain which
used to be given as the results of the observation of the rain-
gauge (but which have lately been seemingly better attended
to), shake the faith of the meteorologist in any of the observa-
tions published under the sanction of the Royal Society.
Surely there ought to be one maker appointed to construct
every instrument used by Societies, whether Royal or not,
and by those who, living at a distance from towns, would still
wish to compare their observations with those of others. The
great attention which is now paid to meteorology as a branch
of science demands that something should be done to secure
the agreement of all instruments used by observers of the
weather. Several pages of some scientific Journal should

Mr. Talbot on the Repulsive Power of Heat. 189

also be devoted to the publication of the monthly results (ac-
cording to a fixed tabular form) of observations taken in va-
rious parts, not only of this kingdom, but of the whole world,

if possible. I am, Gentlemen, yours obediently,
JosEPH ATKINSON,
Carlisle, Dec. 1, 1835. Sec. of the Carlisle Lit. and Phil. Soc.

XXXVI. On the repulsive Power of Heat. By H.¥.Tarzor,
Esq.) F.L.S.*

Experiment 1.—On the Vaporization of Sulphur.
W HEN a minute portion of sulphur is warmed between

two plates of glass, it sublimes, and forms gray nebulous
patches, which are very curious microscopic objects. Each
cluster consists of thousands of transparent globules, exactly
imitating in miniature the nebulz which we see figured in
treatises on astronomy}. By observing those particles which
are larger than the others, we find their figure not to be
spherical, but plano-convex, with the flat side to the glass.
Being very transparent, each of them acts the part of a little
lens, and forms in its focus the image of a distant light, which
can be perceived even in the smaller globules until it vanishes
from minuteness. If they are examined again after a certain
number of hours, the smaller globules are generally found to
retain their transparency, while the larger ones are become
opake, in consequence of some internal change in the arrange-
ment of their molecules. I find that Mitscherlich and others
have noticed this property in sulphur of undergoing a sponta-
neous change}. There is a circumstance attending this expe-
riment which deserves particular attention. Although the
sulphur has been sublimed by heating it over a Jamp between
two plates of glass almost in contact with one another, yet the
globules are found adhering to the upper glass only; and as
their number amounts generally to many thousands, it is evi-
dent that the preference which they thus exhibit to the upper
glass must have some strong determining cause.
The reason of it is, no doubt, that the upper glass is a little
cooler than the lower one; and by this means we see that the
vapour of sulphur is very powerfully repelled§ by heated

* Communicated by the Author.

+ And owing, perhaps, their mutual disposition to the same general
laws of attraction as the Nebula ?—Eprr.

¢ See Phil. Mag. and Annals, N.S., vol. iii. p. 144, 152, for correlative
facts.—Epit.

This is a very beautiful instance in corroboration and extension of

Prof. Powell’s experiment described in the Phil. Trans. 1834, part ii.
p- 485.—Epit.

190 Mr. Talbot on the Repulsive Power of Heat.

glass. The plano-convex form of the particles is owing to
the force with which they endeavour to recede from the lower
glass, and their consequent pressure against the surface of the
upper one. I think this experiment is a satisfactory argu-
ment in favour of the repulsive power of heat, and I believe
it has not been hitherto described.

Experiment 2.—On the Vaporization of Arsenic.

When a particle of arsenic is sublimed between two plates
of glass, it forms nebulous patches, considerably resembling
those formed by sulphur in the preceding experiment. But
the microscope detects a great difference. Instead of a glo-
bular or semiglobular form, the particles of arsenic are cry-
stallized. ‘The minuteness of some of the crystals almost ex-
ceeds calculation. I would suggest the employment of this
method to detect the presence of arsenic in minute quantities
of matter. The difficulty of demonstrating its presence with
sufficient certainty is shown by the number of chemical essays
that have been written on the subject, while a particle of the
size of a pin’s head is amply sufficient to display this micro-
scropic crystallization; and the form of the crystals being di-
stinct and definite, the observer can soon make himself ac-
quainted with their figure, so as to run little risk of mistaking
any other substance for them.

Note on Radiant Heat.

M. Melloni says (in the Number of this Journal for Decem-
ber last, vol. vii. p. 475,) that

‘** For a long time the immediate transmission of terrestrial
radiant heat by transparent substances, both solid and liquid,
has been denied; and the opinion has become prevalent that
we see in experiments of this kind only an effect of the heat
absorbed by the body submitted to the calorific radiation.”

This “ prevalent opinion” he has shown to be erroneous,
but by experiments which are too delicate to be repeated with
facility.

As a popular illustration of the fact, therefore, seems to
be wanted, I subjoin the following rude but convincing expe-
riment.

Let a poker be heated bright red hot, and having thrown
open a window, approach the poker quickly to the outs¢de of
a pane, and the hand to the inside. A strong heat is felt at
the instant, which ceases as soon as the poker is withdrawn,
and may be again renewed, and made to cease as quickly as
before. Now, everybody knows that if a piece of glass is so
much warmed as to convey this impression of heat to the

rt 4

Dr. Inglis’s Extracts from his Prize Essay on Iodine. 191

hand, it will retain some part of that heat for a minute or
more; but in this experiment the heat vanishes in a mo-
ment. It is not, therefore, heated glass which we feel, but
heat which has come through the glass, in a free or radiant
state.

XXXVII. Extracts from a Prize Essay on Iodine. By James
7 Ineuis, M.D.

[Continued from p. 20, and concluded. ]

I MENTIONED before that Serullas had proposed iodic
acid as a test for the vegetable alkalies. I find that hydriodic
acid may be used as such also. To the sulphate of quinine
I added in solution a few drops of sulphuric acid, so that the
sulphate might be soluble in water. I next added a solution
of hydriodate of potassa; instantly there was a yellow preci-
pitation, which became gradually ofa greenish colour. I added
more hydriodate, and the precipitation of yellow iodide of
quinine still took place, which finally became of a reddish
brown colour. I have not examined this compound, but call it
iodide of quinine, the hydriodates being all soluble; and I do
not see how it could be an iodate.

I find also that the hydriodate of potassa throws down a
white precipitate with tincture of capsicum. I cannot deci-
dedly say that this acid is as good a general test as the io-
di * * * *

I wished to obtain a compound of cyanogen with iodine,
and for this purpose made a solution of bicyanuret of mer-
cury in water, which I added to an alcoholic solution of io-
dine; immediately the red biniodide of mercury fell, and the
action I thought to be this:

L atom of ‘) Cyanogen. Bicyanuret
bicyanuret | Cyanope eae of iodine.
of mercury. | Mercury.
\ ‘
3 atoms Iodine. .
of Iodine. . Biniodide
iodine. J Iodine.. of mercury.

If too much cyanuret of mercury be added, then all the
precipitation is red. But if there be only sufficient, then a
lightish brown powder in crystals falls. I boiled and strained
off the supernatant liquor from the biniodide of mercury, and
Jaid it aside to crystallize; but this could not be effected.
The liquid is exceedingly pungent, and exhales a vapour

192 Dr. Inglis’s Extracts from his Prize Essay on Iodine.

painful to the eyes. When added to water a copious yellow
precipitation takes place. It contains about two thirds of al-
cohol; is, when pure, of a clear amber colour; when placed on
the skin it causes a painful sensation, and excites an inflam-
matory blush. It, after being boiled, deposits acicular red
crystals, interspersed with yellow ones of a similar shape.
Even when much diluted with either water or alcohol, the
odour and taste of this new cyanide are very pungent. * * *

I next wished to obtain an iodide of chromium, and this
I endeavoured to do in the same manner as the chloride is
got. I mixed adrachm of the hydriodate of potassa with
half a drachm of the bichromate of potassa, and adding
fuming sulphuric acid, I distilled; but could not succeed in
procuring it. In the Lond. and Edinb. Phil. Mag. and Jour-
nal of Science, (No. 15. September, 1833, vol. iii. p. 235,)
I observed that M. Peligot describes a compound of chromic
acid with metallic chlorides. I thought that some analogous
compound might be formed with the metallic iodides.

To the bichromate of potassa in solution, and when boiling,
I added concentrated hydriodic acid in excess. A consider-
able portion of iodine is evolved, and a thick black compound
formed, having iodine in excess.. I put a portion of this into
water, and having boiled it, laid it aside to cool. No crystal-
lization took place, but the solution was of a decided green
colour.

The black compound when dried and broken into pieces
resembles kino; it is of a dark green colour, with considerable
lustre, and is friable. The liquid that drained from it gave
crystals of hydriodate of potash. ‘The action I suppose to be
as follows :

Chromic acid.
Chromic acid.
Potassium. ...

Chromate of potassa.

Oxygen. ...... Water.
Hydrogen.
Todine...... Chromate of the iodide
Potassa..... of potassium.

I thought that hydrocyanic acid, being of easy decomposi-
tion, would, when combined with tincture of iodine, give hy-
driodic acid and a cyanuret of iodine. I allowed them to react
on each other for some weeks; no deposition was observed,
but on testing the fluid, hydriodic acid is readily detected. I

consider this solution as a hydriodate of the iodide of cyano-
gen.” a eae Oe ae ae

ee

ee el

XXXVITI. On the Anatomical and Optical Structure of the
crystalline Lenses of Animals, particularly that of the Cod.
By Sir Davip Brewster, LZ.D., F.R.S., V.P.RS. Ed.

[ With a Plate. ]

[From the Philosophical Transactions for 1833, p. 323-332;
with additions. ]

AVING observed very singular phzenomena in the cry-
stalline lenses of fishes and quadrupeds when exposed to
polarized light, I was led to examine their anatomical struc-
ture, with the view of ascertaining if it had any relation to
these optical appearances. Leeuwenhoek and Sattig had pre-
viously made some progress in this research, but their methods
of observation were ill fitted for so delicate an inquiry, and
experience soon convinced me that the structure of the lens
could not be thoroughly investigated either by the microscope
or the scalpel.

Anatomists had long regarded the crystalline lens as com-
posed of concentric laminz, and these laminze of minute fibres;
but M. Soemmerring, in his work on the Human Eye, pub-
lished in 1804, regards this structure as the effect merely of
maceration in alcohol, and maintains that it does not exist in
the recent or the living eye*. This decision, which its author
has supported by many plausible but unphilosophical and in-
efficient arguments, appeared to set aside all the results which
had been obtained by preceding inquirers, and rendered it
necessary for me to adopt a new mode of investigation, which
should not be liable to the same criticism.

The crystalline lens of the cod, like almost all globular
lenses, has the form of a prolate spheroid, the axis of revolu-
tion being a little longer than the equatorial diameter. ‘This
axis is the axis of the eye, or of vision.

The body or substance of the lens is inclosed in an exceed-
ingly thin and transparent membrane, called its capsule; and
this membrane is so elastic that when it was stretched upon a
plate of glass, the extended portion polarized a blueish white
tint of the first order. If we puncture the capsule, a thickish
fluid flows from the opening ; ; but upon removing the capsule
altogether, this fluid is found to constitute only the outer coat
of the lens, the substance of the lens growing denser and
harder as we approach to the centre of it.

The body of the lens is not connected with the capsule, as

* “Lens, post mortem ita tractata, etiamsiin segmenta spheerica, laminas
et fibras dehiscat, tamen minime inde sequitur lentem recentem seu vivam
ex ejusmodi fibris, lamellis et segmentis spheericis conflari, aut per vitam
lentis sanz fabricam zeolitidi ullo modo similem esse.”—pp. 67, 68.

Third Series. Vol. 8. No. 46. March 1836. ee

194 Sir David Brewster on the Anatomical and Optical

Dr. Young supposed, by any nerves or filaments whatever :
on the contrary, it floats as it were within the capsule; and in
holding the lens in my hand, I observed its axis of revolution
take a horizontal position whenever it was placed in an in-
clined direction. This observation I repeated many times with
the same lens, though I have not been able to do it with others.

When the lens is taken out of its capsule, and the softer
parts removed by rubbing it between the finger and the thumb,
we obtain a hard nucleus, the structure of which we shall now
proceed to examine. In order to get rid of Soemmerring’s
objections, I have often removed the recent lens from a newly
caught fish, and taken out the nucleus without exposing it to
any process of maceration or induration. I then detach a film
or two from the nucleus, and find it to consist of regular trans-
parent laminz of uniform thickness, and capable of being se-
parated like those of sulphate of lime or mica. The surface
of these laminz is perfectly smooth, and reflects light as co-
piously as any other polished substance of the same refractive
power*.

When we look with a microscope at the surface of any la-
mina, before it has been detached, it has the appearance of a
grooved surface, like mother-of-pearl, or one of Mr. Barton’s
iris surfaces; and in large lenses it is often easy to trace these
apparent grooves or lines to the two poles of the axis of revo-
lution, the lines being widest at the equator, and growing nar-
rower and narrower as they approach the poles. In small
lenses, however, it is extremely difficult, and often impossible,
to follow these lines to their points of convergency by the use

. . to} .
of the microscope ; and hence both Leeuwenhoek and Sattig

maintained, that in fishes the points of convergency formed:

a line at each pole, the line at the one pole being perpendi-
cular to the line at the other. These lines are bisected by
the polar point, and the parts of the line on each side of the
pole are called septa. Hence the lines or fibres which com-
pose the laminz are related to two septa in fishes, according
to Leeuwenhoek and Sattig.

In examining these phenomena, I observed the surface of
the lamine sparkling with the colours of mother-of-pearl +,
and upon applying a microscope, adjusted to such a focus as
to show distinctly the reflected image of the candle, I observed

* The objections urged by Soemmerring may be still more completely
removed by examining the lenses when newly taken out of the eye and im-
mersed in a glass trough of distilled water. In many cases the septa and
the fibres will be distinctly seen before it is possible that the lens could
have undergone any change whatever.

+ ites colours may be transferred to wax, &c., like those of mother-of-
pearl,

Structure of the Crystalline Lenses of Animals. 195

on each side of this image one or more highly prismatic images,
produced by interference, like those of grooved surfaces.
As the direction of the fibres is necessarily perpendicular to
the line joining the coloured images, I was enabled to trace
them to their termination, or points of convergency, when the
fibres themselves could not be rendered visible by the best
microscope. But while this new method of observation en-
abled me to detect all or most of the varieties of fibrous organi-
zation which exist in the crystalline lenses of animals, it fur-
nished at the same time a simple and accurate method of de-
termining the diameter of the fibres at any point of the sphe-
roid. The distance of any of the coloured images from the
colourless image was a direct measure of the breadth of the
fibres; and with the aid of a series of Mr. Barton’s beautiful
divisions upon steel, from 3125 in an inch to 10,000, which
he was so kind as to make for me, it was easy to obtain these
measures without even the trouble of calculation.

By these means | succeeded in tracing the fibres, or thin
slender lamin, to two poles diametrically opposite to each
other, and coinciding with the poles of the spheroidal lens, as
shown in Plate II. fig. 1. In small lenses, and particularly
in the lenses of birds, the accurate convergency of the fibres
to one focus is less distinctly seen; but it is easy to distinguish
this diffused polarity, as it may be called, from the conver-
gency of the fibres to points arranged in a straight line, and
constituting the two septa already mentioned.

The distribution of the fibres now described is the simplest
that occurs in the lenses of animals. Every fibre has the
same length and the same form; and its curvature is, like the
meridian of a spheroid, without any contrary flexure.

The perfect flatness of the surfaces of the concentric lamine,
as indicated by their power of forming a distinct image by re-
flexion, shows that the fibres which compose them are flat and
not cylindrical; and when we look through them with a pow-
erful microscope, this conclusion is amply confirmed by the
uniform distribution of the refracted light.

In order to measure the diameter, or rather the breadth of
the fibres, I detach from the equator of the lens an extremely
thin lamina, and having placed it above a small aperture in a
plate of brass, I look through it at a candle, and measure the
angular distance of the first coloured image from the white or
central image, taking the centre of the red ray as the point
from which the measurement is to be taken. When the first
coloured images on each side of the central image are ex-
tremely distinct, it will be better to measure the angular di-
stance of the red parts of their spectra, and to take half that

Y2

196 Sir David Brewster on the Anatomical and Optical

distance as the angular distance of the first image from the cen-
tral image. If we call this distance A, and put B for the
breadth of each fibre, or the breadth of the transparent part,
together with the breadth of the opake interval or line which

separates the fibres, we shail then have B = C being a

C
7,
constant quantity for the red ray to be determined by experi-
ment. According to Fraunhofer’s experiments on Interfe-
rence, C is equal to 0°0000256 of an English inch for the
0:0000256
5 ;
In order, however, to save the trouble of calculation, and
in cases where a general estimate only is required, I use Mr.
Barton’s system of grooves already mentioned ; and upon look-
ing through the lamina at the white image, or rather the cen-
tral image of the iris surface, I can at once compare the di-
stance of the first prismatic images of the one with the same
distance in the other. If I am using, for example, the divi-
sions of 5000 in an inch, and if I find the distances of the co-
loured images the same with the laminze and with the steel, I
infer that the breadth B is the 5000dth of an inch. This con-
clusion, however, is not quite correct, for we may have been
comparing the effect of a perpendicular incidence on the la-
mina with the effect of an oblique incidence onthe steel. Now,
Fraunhofer has shown that the coloured images separate as
the incidence in a plane intersecting the grooves at right an-
gles is increased, and that the value of B, to which this in-
creased distance corresponds, is smaller in the proportion of
radius to the cosine of the angle of incidence, I. Hence the

. C
formula becomes B= essen This property gives us the

middle red ray; hence the formula becomes B=

advantage of a variable scale; and in making the experiment,
I found that at an incidence of 25°, when the divisions of 5000
in an inch were employed, the coloured images of the laminze
corresponded with those of the grooved steel. Hence the
value of the quantity B, or the breadth of the fibres, is about
the 5500dth part of an inch.

I next detached laminz from parts nearer the pole, and I
found that the coloured images gradually separated as the
fibres approached to the poles; thus proving, what might have
been inferred from other facts, that the fibres gradually taper
in breadth from the equator to the poles of the lens. In order

* Fraunhofer found that in a system of lines where B was 0:0001223 of
a Paris inch, A was 11° 25! 20": and in another system, where B was
00005919, A was 2° 20! 57’.

Structure of the Crystalline Lenses of Animals. 197

to allow the fibres to be packed without condensation into
spherical laminz, their breadths must diminish as the cosine -
of the distance from the equator.

Although the prolate form of the spheroid indicates that
the thickness of the laminz, or of their component fibres,
must increase slightly towards the poles, yet I have not been
able to prove this experimentaily, or even to determine the
thickness of the fibres. I have more than once detached, by
accident, a single fibre from the mass, and by an examination
of the black line which forms its edges, I am satisfied that its
thickness is at least five times less than its maximum breadth.

Having thus determined the form and size of the fibres, we
come now to a very delicate and interesting part of the inquiry,
namely, to ascertain the mode in which the fibres are laterally
united to each other, so as to resist separation, and form a
continuous spherical surface. The remarkable mechanism by
which this is effected was first pointed out to me by an optical
phaenomenon. In looking ata bright light through a thin lamina
of the lens of a cod, I observed two faint and broad prismatic
images, situated in a line exactly perpendicular to that which
joined the common coloured images. Their angular distance
from the central image was nearly five times greater than that
of the first ordinary prismatic images, and no doubt whatever
could be entertained that they were owing to a number of
minute lines perpendicular to the direction of the fibres, and

whose distance did not exceed the x 5, or the 12,500dth

1
2500
of an inch.

Upon applying a good microscope to a well-prepared lami-
na, I was delighted to observe the structure shown in fig. 2,
where the two fibres, a 6, bc, are united by a series of teeth,
exactly like those of rackwork, the projecting teeth of one fibre
entering into the hollows between the teeth of the adjacent one.
The length of the teeth, or 2p, is equal to about one half of
mn, and this length of course diminishes towards the pole in
the same ratio with the fibre. The breadth of the teeth is
such, that five of them, namely, three of one fibre together
with the two teeth of the adjacent fibre, which they inclose,
are equal nearly to mn + np, which is the measure of the
quantity B in the preceding formula. With an ordinary mi-
croscope, the series of teeth between any two fibres seem to
form a dark line, whose breadth is np; and it is in conse-
quence of the interruption of the light thus occasioned, when
the Jamina is dry, and the surfaces not in optical contact, that
the fibrous lamina acts upon light like grooved steel, the space
np in the lamina corresponding to the groove formed by the
cutting diamond point in the metallic surface.

198 Sir David Brewster on the Anatomical and Optical

Although the parallel sides of the teeth do not form con-
tinuous lines, yet they produce colours by interference in the
same manner as if they were continuous; and it is by their
influence that the secondary prismatic images are produced
in a line perpendicular to the sides of the teeth. In the living
as well as in the recent lens the faces of the teeth and of the
fibres are all in optical contact, and light passes through them
in every direction in the same manner as if the whole lens
were a continuous solid.

The toothed structure which has now been described, I
have found in the salmon, haddock, herring, shark, and, in-
deed, in the lens of every fish where I have looked for it; and
in this class of animals it is generally very distinct, and almost
always capable of producing the secondary prismatic images.
In the salmon, however, the teeth are much narrower than in
the cod, and the colours which they produce are less distinctly
seen.

Having thus determined the form and magnitude of the
fibres and their teeth in a given lamina, it becomes interesting
to ascertain if they suffer any change in shape or size at differ-
ent distances from the centre of the lens. With this view I
continued to remove one coat of the lens after another, till I re-
duced it to such a minute nucleus that I could no longer use
it. I then dried it at the fire, and having crushed it, I ob-
tained small portions of lamina extremely near the centre: in
this way I found that the fibres gradually diminished towards
the centre of the lens, and the teeth in the same proportion,
so that the number of fibres in any spherical coat or lamina
was the same from whatever part of the lens it was detached.

In the lens of a cod, I found that there were 2000 fibres in
an inch at the equator of a spherical coat or lamina, whose
radius was ths of an inch; consequently there must have
been 2500 in the spherical surface*. If we now suppose that
the breadth of each fibre is five times its thickness, and that
each tooth is equal to the thickness of the fibre, or that five
teeth are equal in breadth to a fibre, we shal! obtain the fol-
lowing results for the lens of a cod four tenths of an inch in
diameter :

Number of fibres in each Jamina or oe 2,500
WICH COAL cet vice’ sfechwcioas'eiss

= hoot am,.eaeh: Dbre: \duios<sas ews 12,500

—__—- - ——— in each spherical coat... 31,250,000

— fibres in the lens ..........00008 5,000,000

— teeth in the lens ...........00.. 62,500,000,000
or, to express the result in words, the Jens of a small cod con-

* The radius being .*, or *2, we have 3:1416 x°4 x 2000 = 2513.

=

Structure of the Crystalline Lenses of Animals. 199

tains five millions of fibres, and sixty-two thousand five hun-
dred millions of teeth. A transparent lens exhibiting such a
specimen of mechanism may well excite our astonishment and
admiration !

The magnitude of the fibres and of their teeth varies in
different animals. In the lens of a South American fish, for
example, called the sheep-head, there are only 613 fibres in a
spherical surface*; but it will be seen in a subsequent paper,
that there are other animals in which the fibres are still more
minute than those in the lens of the cod.

By means of very fine microscopes, with high magnifying
powers, I have succeeded in detecting the same structure in
the lenses of birds and quadrupeds; but in these classes of
animals it is much less distinctly developed than in fishes.
The teeth are much shorter; and when the lens belonged to
an aged animal, the toothed structure was extremely indistinct
and irregular, and in some parts of the fibres it entirely dis-
appeared.

The fibrous structure represented in fig. 1, and in which
the fibres converge to two opposite poles, is never found, in
so far as my observations extend, in any of the Mammalia
or Cetacea. It is the universal structure in the lenses of all the
birds that I have examined; and though it is the most com-
mon structure in fishes, it is pot the only one which they ex-
hibit. In the following table, I have given the names of the
different animals in whose lenses I have found the structure
shown in fig. 1.

FIsHEs.
Cod. Loch-Leven Trout. Mackerel.
Haddock. Turbot. Coal Fish.
Serpent Fish. Sole. Gold Fish.
Diver. Sayd. Great Lamprey.
Mullet. Grey Dog. Bull-head.
Herring. Flying Fish. Whiting, English.
Holibut. Frog Fish. Pout.
Fresh-water Fluke. Sea Cat. Dab.
Salt-water Fluke. Eel. Plaice.
Spirling. Pike. Lumpsucker.
Birps.
Cassowary. Turkey. Curlew.
Albatross. Barnacle Goose. Chaffinch.
Pelican. Sea Eagle. Thrush.
Crane. Snowy Owl. Magpie.

* The diameter of the lens was 1th of an inch, and there were 975
fibres in an inch at the equator.

200 Sir David Brewster on the Aatomical and Optical

Plover. Cock. Adjutant.
Common Pigeon. Hen. Peacock.
Wood Pigeon. Green Linnet. Kite.
Emberiza. [ Ornithorhynchus.] Raven.
Alauda arvensis. Red-tailed Hawk. Gray Parrot.
Tringa. Trumpeter. Nicobar Pigeon.
Black Grous. Vulture, Indian. Crested Curassow.
Red Grous. Cireaetes brachy- Mandarine Duck.
Partridge. dactylus. Chukar Partridge.
Wild Duck. Crested Guan. Owl, Indian.
Pheasant. Condor. [ Macacus Cynomol-
Penguin. Rhea Ostrich. gus*. |
Lizarps.
Lacerta striata. Lacerta Calotes.

For many of the lenses in the preceding table, and for
others which I shall have occasion to enumerate in subsequent
communications, I have been indebted to the kindness and
zeal of Captain Basil Hall, Captain Robertson, Professor Grant,
Mr. George Swinton, Dr. Knox, Mr. William Clark, and
Mrs. Green of Cumberland Island.

In the Philosophical Transactions for 1816, I have de-
scribed and represented by drawings the singular structure
of the crystalline lens of the cod, as exhibited by transmitting
through it a beam of polarized light. I have there shown that
it consists of three different structures; viz. the nucleus, which
has negative double refraction like calcareous spar; the ex-
ternal strata, which have the same kind of double refraction ;
and the intermediate strata, which have positive double re-
fraction like zircon. The axis of vision, or that of the sphe-
roidal lens, is the axis of double refraction for these three
structures. I have discovered the same structure in the lens
of the haddock, the salmon, the frog-fish, the skate, and the
whiting, and indeed, with more or less distinctness, in all the
lenses of fishes which were large enough to show the polarized
tints.

A doubly refracting structure, related to the axis of vision,
is distinctly seen in the human lens, and in that of quadrupeds
and birds; but it differs considerably, both in its character
and intensity, from that which exists in the lenses of fishes.
In the paper to which I have already referredt, I have stated

* For the lenses cf most of these birds, &c. and many others which will
be described in subsequent papers, I have been indebted to the liberality
of the Zoological Society.

+ Philosophical Transactions 1816, p: 315.

Structure of the Crystalline Lenses of Animals. 201

that in the lenses of sheep and oxen there is only one series
of luminous sectors, or one structure, corresponding with the
intermediate set in the crystalline of fishes. This, however,
is a mistake. By nicer means of observation I can distinctly
see all the three structures in the lens of the sheep, the ox,
and the horse; but, what is very singular, the nucleus and
outer structure have positive double refraction, while the
double refraction of the intermediate structure is negative ;
a result exactly the reverse of that which I have obtained
from the lenses of fishes*. If this triple structure is intended,
as I have already conjectured, to correct aberration, or to im-
prove vision, it will be a curious problem to determine how
this is effected, and to connect the one structure with the ex-
istence of a spheroidal lens without the aqueous humour, and
the other with the coexistence of a flat lens and an aqueous
humour.

When the lens of a cod is prepared so as to indurate and
retain its form and transparency, the process of induration
confounds all the three structures in one; viz. a negative
doubly refracting structure many times more intense than that
which exists in the recent lens. When a lens thus indurated
was exposed to polarized light, I observed round the axis of
the lens a beautiful system of negative uniaxal rings, seven in
number, and intersected with a well-defined black cross.
When the polarized light passed through any equatorial dia-
meter of the lens, a system of seven biaxal rings was beauti-
fully displayed, the principal axis being of course negative.
This system of rings was intersected by the black cross,
when the plane of the equator coincided with that of primi-
tive polarization, and they displayed the two dark hyperbolic
branches when the inclination of these planes was 45°. These
phenomena I observed most distinctly in the lens of the
boneta; and I have seen them also in the lenses of the cod,
the shark, and the flying-fish, which happened to have been
preserved without any fissures or loss of transparency.

In looking at a candle through the indurated lens of a cod,

* Since this paper was printed in the Philosophical Transactions, I have
been able to examine the lenses of the Sheep, the, Horse, and the Cow,
at various ages, and to discover differences in the polarizing structure de-
pending upon the age of the animal ; but, what is very strange, I have seen
the polarizing structure change after death, and when one lens was placed
in distilled water, and exhibited only two series of sectors,"both positive,
I have observed the formation and development of two additional series
of sectors, both negative, the one between the two positive series of sectors,
and the other at the external margin, thus making four series, viz.

+, —, +, —, commencing from the centre of the lens.

Third Series. Vol. 8. No. 46. March 1836. Z

202 Prof. Wagner’s Observations on

held at a distance from the eye, and which had been preserved
for three years, I observed the candle encircled with three
beautiful concentric rings, red on the inside and green with-
out. ‘Phese colours were no doubt those of mixed plates.

In examining the lamin of the crystalline lens under the
microscope, we are often perplexed with a variety of colours
apparently spread over the surface of the plate. These co-
lours are not the effect of chromatic aberration, but arise from
the interference of the coloured pencils produced by the two
surfaces of the laminze. If we take a thin lamina, and, hold-
ing it opposite to a candle, look at its surface with a lens
about an inch in focus, we shall see the whole of it covered
with the most brilliant and varied colours, not inferior to
those of the richest opal. These colours vary as we incline
the laminz in a plane cutting the fibres of it perpendicularly;
and when the portion of the lamina is flat, they form a series
of rectilineal serrated fringes perpendicular to the direction
of the fibres. When the portion of the lamina is much curved,
the fringes are irregular, and form, occasionally, returning
curves of every variety of form and of every imaginable tint.
If we immerse one of the surfaces of the lamina in a fluid of
the same refractive power, we remove, as it were, the fibrous
structure of ihat surface, and the serrated fringes immediately
disappear. ‘This observation led me to imitate these fringes
by combining two series of grooves cut on the surface of se-

arate strips of glass*. The effects were precisely similar
and highly beautiful; and in the prosecution of the subject
I was led to the observation of a series of very curious phz-
nomena, which will form the subject of a separate communi-
cation.

XXXIX. Observations on ‘the Compound Eyes of Insects.
By Rupotew Waener, Professor in Erlangen.t+

O* examining the works of Jehn Miiller on the Eyes of
Insects, with a view to the 2nd Part of my Manual of
Comparative Anatomy, I have only been able, as might be
expected, to confirm the greater part of his statements. But
with respect to the very interesting structure of the compound
eye I have arrived at a different opinion. Strauss, indeed,
represents small knob-shaped, or rather cup-shaped, ganglions
of the fibres of the optic nerve, which Miller and Duges

* These phenomena are much more splendid, when the grooves are
formed upon thin plates of isinglass, by taking an impression of them front
a steel surface,

+ From Wiegmann’s Archiv fiir Naturgeschichte, 3° Heft, 1835; com-
wunicated by Mr. William Francis, Berlin.

the Compound Eyes of Insects. 208

deny. In Sphinx Atropos, however, I first observed how the
fibres of the optic nerve surround the apex of the conical
lenses. like a cup, and pass forwards over the lens to its an-
terior facet and to the cornea. ‘The nerve, therefore, forms a
true retina which surrounds the crystalline lens like a capsule.
The nervous fibril is readily broken off under the apex of the
cone, but the retina is also always perceptible at this part.
The reason why this has been overlooked appears to me to
be that they used too weak magnifiers; with a magnifying
power of 300 times my statements will be confirmed. I have
often repeated the observations on Beetles, (for example, on
Melolontha,) on Papiliones, (for example, on Pap. Urtice,)
and others. Whether the crystalline lenses are cylindrical or
hexagonal is difficult to say; and even where they may be
6-angular, as in Melolontha, of which I am still doubtful, the
angles must be much rounded. In Mel. vulgaris (Plate IT. fic.
3.), and more distinctlyin Mel. Fullo (fig. 5.) veachlens appeared
to me to consist of six three-sided prisms, whose bases are di-
rected outwards, so that they with their apices rejoin one an-
other convergent in the axis of the lens. Ata is the Jens,
inclosed by the sheath of its retina and entire, at bisected ;
two prisms cover the third, which lies under them. c is a
single prism from the side; d a similar one seen from the
side opposite to the basis, (fig. 4. of Sphinx Atropos).

If this statement be true, the eyes of insects will appear
only single ones inwardly aggregated; behind each cornea lies
a crystalline lens with retina and choroidea; the layer of pig-
mentum takes the place of the latter. The rays of the axis,
therefore, would not alone, as Muller supposes, fall on the
nerves, nor the other rays be absorbed by the pigment, but
would fall on the retina exactly as in the human eye. I have
not yet examined the construction in the pyriform crystalline
Jenses without the cornea subdivided into facets.

We thus discover every day a greater complexity of ap-
parently simple organs, and a closer analogy with the human
construction, even in the Invertebrated animals. I think I find
a greater perfection in the organization of the eyes in the An-
nelida, particularly in Hirudo, for instance. See my Lehrbuch
der Vergleichende Anatomie, 2te Abtheilung, p. 428.

[ Note.—Since these observations on the compound eyes of the Lepido-
pterous Insects were published by Wagner, a similar structure has been
detected by Burmeister in the compound eyes of some of the Branchiopo-
dous Crustacea.—Ep1r- |

Z2

[ 204 ]

XL. On the Formula for the Dispersion of Light derived from
M. Cauchy’s Theory. By the Rev. Baven Powet1, M.4A.,
F.R.S., Savilian Professor of Geometry, Oxford.

(Continued from p. 24.)

N a former Number of this Journal I stated in a general
way the nature of some considerations of importance re-
specting the formula of dispersion deduced from M. Cauchy’s
theory, promising at the same time to give some further ac-
count of the other researches of Sir W. R. Hamilton, with
which it is connected, and of which the author has kindly
allowed me to make use. In saying that that eminent mathe-
matician had “taken up the subject,” I beg it to be under-
stood (and I mention it at his request,) that I allude to no
other investigations than what are here to be given. In the
present paper, therefore, I shall proceed to explain his method
of comparing, in the first place, the degree in which the ap-
proximate and exact formulas accord with each other; and
in the second, the analysis by which he deduces a process of
computation by the exact formula: the numerical results, as
derived from the two methods, will then be compared. Some
illustrations of other points will form the subject of a future
communication.
Upon the principles explained in the last paper, if we take
the development of the sine divided by the arc, and square
the polynomial, using the approximate formula,

] sin 6,\2
a> js Bef i ') (1.)
we shall have

1 H 2 1 H,? 6,2 2 H,2 4

Sg ey eg Ea fh a ae i? O4—, &e. (2.)

2

But if we use the exact formula,
1 k > (sin 6y*
ihn s{ (=) \ (3.)

. - A
and substitute for @ its value a

we shall in like manner have,

1 2 Diamine Z 2 4
p= S(H)- Z (5) Sad) +e () Scag)

=), Occ. (4.)

ue

On the Formula for the Dispersion of Light. 205

Now, to compare this with the approximate development
(2.) we may assume

H, = vS(H?)
_ 7, /S (He!)
eee. vie
which being substituted in (2.) will give
ry w/e ope era 2/2" \*[S.(H?Ae*) |?
a= 8(H)— 3(5) SHA) + GIS) “song
== 18 &e. (6.)

Hence it is manifest that by our assumption of H, and @,
in the approximate formula, the two first terms of both deve-
lopments are identical; but the third and subsequent terms
will differ. We thus obtain an idea of the degree in which
the approximation deviates from the truth,

In the next place, adopting the exact development (4.) we
may proceed to the important discussion of a method of de-
termining the coefficients, and of actually computing the
value of »% in any given case. The development may be ex-
pressed in the following form, writing single letters for the
coefficients :

1 Fiih ee S gts

== A,— Ai(=) + Ao(—] —, &e. (7.)
Now, if r be the time of a vibration, or, what is the same

thing, of the propagation of a wave, « being the reciprocal of

the velocity, we shall have

pt ay
i eae
Thus the series (7.) becomes
! oan we wy"
ap = Ao Ai), +4 (2) BAe (8.)

Again, we might substitute other letters for the coefficients
by making them include the powers of » so as to express the

4, 1 :
series in powers of tee only. By extracting the root, and

developing the reciprocal of the polynomial, it will be easily
seen that the series resulting will be still one of the same

powers of (=), and may be expressed in this form,

9

= a + a, (=) + a, (on +, &c. (9.)

206 ~—— Prof. Powell’s Formula for Dispersion of Light

Now, if we substitute this value of « in each term of the
following expression derived from (8), viz.

pe po
O= —1+ Apwi— A, + Ag - &e. (10.)

we shall have

(=I + Ag [ao + a, t*? + &e.]?

| + Av fiag +.a,77? +,&c.)*.077 \, , (11.)

(VS
| + Ag [ao +4, 77? + &e.]®°. r*

e &c.

If in this expression we collect the coefficients of the same
powers of r and equate them respectively to zero, we shall at
length obtain,

=
4% = ve -

a, =iA,A,? (12.)
Cay A, Ae a A, hare

We might continue the process: but confining ourselves to
the three first terms, we find, Ist, that a) a, are positive; and
a, may probably be so; Zndly, that, since the first coeffi-
cients A, A,, &c. are all independent of u, and since we have
values of the second set a a, in terms of these only, therefore
these last are also zndependent of »%, that is, are constant for
all rays in the same medium, but differ for different media.
Thus in the series (9.) the value of » will differ only by the
change in the factor 7, that is, for rays whose times of vibra-
tion are different, or, in other words, for rays whose lengths of
waves are different, that is, for the different primary rays.
We shall thus obtain the means of calculating the value of »
for each ray independently of the medium, supposing we may
restrict ourselves to the three first terms. For we have the
three constants a @, @. the same in the series for each ray ;
thus if we take such serieses for any four rays we can eliminate
the three constants.

Let us then consider the four rays (in Fraunhofer’s nota-
tion) B, D, F, H; for any one medium, we shall have this sy-
stem of equations, viz.

rt Q a5
bp = A + 4, TR + GTR” )

_

Hp = A + a tH + Me | (13.)
sp
2 -2 ~4

bp = 4 + TR + Age |

Py = % + TH + a, TH J

derived from M. Cauchy’s Theory. 207

Between these it is possible to eliminate the three medium-con-
stants a) a, @., and thus to deduce a general relation, valid
for all media, between the four indices ph, Hp Hp My» and the
four periodic times tz tp Tp Ty.

Now, a little consideration will show that this relation can
only involve the two ratios of the three differences of the four
indices, and the two ratios of the three differences of the four
reciprocals of the squares of the periodic times. Taking
these we may for abridgement write,

Py —& =

PESOS BY Sag? VE RIEL Be Sp (14.)
Profs Pu Ps

ciate lage 7 Bt a i penile A (15.)
Paeitg, May ar ig re

Then it will appear that the result of elimination will be a
relation between the four quantities s, sp tp tp only; and will

not involve the four other quantities hp, My Ty Ty if we pre-

viously substitute for #4 wp tp’ rp” their respective expres-

sions deduced from (14.) and (15.), which are
Hp = Pp +Sp Hu—Ps) I
Hp = Hy + Sp (Hyp)

oe? =\t9° + ty (a 75°) ;

ta = ahs at (7H —T3°)

(16.)

(17)

This result of elimination will therefore be the same as if in
the equations (13.) we had supposed

4
to

II

™~

D ie ts ie (18.)
ae pe be. =. tp

ols Oieatia =e Ola iG,| J

that is, the same as if we eliminated any two new quantities
b and c between the three new equations

Sm = btp + ¢t,*

: (19.)

“a
7"
Il
~
=
=
a
™~

Z08 Prof. Powell’s Formula for the Dispersion of Light

This last elimination is easy, and gives as the relation sought
the following :

Ss 1—+t Ss 1-—t
eee ¥ Be Ry ee gt or (20.)
be so pute ih ei stead

This relation may be expanded by substituting the values
(14.) and (15.) so as to put it under the form,

( (+p ~Fs) (TH wuin e) (TR —T;) ae
0 = 2 —(up—Hp) (ta —*5°) (75°73) (FH — 75’) r fet)

L4(@u—Fs) (tr’—TB°) tp’ — TB’) (te TD) J

and in this way the relation (20.) may be verified, as it will
then be found to be satisfied independently of the three me-
dium-constants a) a, a, by the expression (13.) for the four
indices.

Now, to proceed to the actual calculation, we have Fraun-
hofer’s values of A for the standard rays; these are obtained
from interference, and are absolutely independent of any me-
dium. Now if ¢' the time which light takes to traverse a
given length J' zm vacuo, will obviously have

t! hal EH

Pie KE
If then we take ¢’ as the unit of time, we have for the time
of a vibration 7m vacuo

Aa
T= i ih
Thus if 7’ = ,5455 inch, since by Fraunhofer’s observa-
tions we have ~ = ‘00002451 inch, it follows that we have

axis "BABL aa similarly
tp = 2175 tp = "1794 ty = 4G. = (22)

Now, there is a circumstance which may be remarked
among these numbers, which affords a considerable facility in
our calculation. The square of +, will be found to be almost
exactly an harmonic mean between the square of the extreme
values t, T,,: or we have

te? = 2 (ty + 73) (23.)
so that in the notation of 5.)

yee (24.)

derived from M. Cauchy’s Theory, 209

Availing ourselves of this circumstance we may put the re-
lation (20.) or (21.) under the simpler form

4 Sptp(l1—-4p) —Sp = 4 (1-26) (25.)
or, what is equivalent,
My Pp = Up (up—Hg) + by (un—2 Hy +s) (26.)
whence ay = — (1—2¢,) = —tp (1-2 ¢p)

which are wholly functions of the values of +, viz.

4p — el 7 2 eo (27.)
fi 1a. ta ~2tp +R"
by nae eS ae e TA eal = ; (28.)

Thus employing the values (22.) of T; Tp Ty the follow-
ing numbers result :

log (—ap) = 1:80441
log (—b,) = 1:06281

Now, to take an example of a particular medium; for flint
glass, No. 13, Fraunhofer found

bp = 16277 bp = 1'6483 My = 1°6711.

Hence by (26.) and the above logarithms, we may calculate
the value of »,, which will be found to result

My = 163492;
by Fraunhofer’s observation it was
My = 1°6350.

Such is the method of Sir W. R. Hamilton: he has, how-
ever, not only calculated this example, but has gone through
the values of the index, for the same ray D in all the media
examined by Fraunhofer. These results I will subjoin, add-
ing a column of the same values as computed by myself, by

a tentative method with only the approximate formula, from
my paper in the Philosophical Transactions.

Third Series. Vol. 8. No. 46. March 1836. 2A

210 On the Formula for the Dispersion of Light.

By My #,
Medium, Calculated Calculated
fedinm Observed by by theexact | by the approxi-
Fraunhofer. Formula. mate Formula.

——— el — eee eee —EEEEEE——EES

Flint-glass 13. 1°6350 1°63492 1°6355

Do. 93. 1°6337 1°63350 1°6335
Do. 30. 1°6306 1°63051 1°6305
Do. 3. 1:6085 1°60825 1°6079
Crown-glass M. 1°5591 1°55901 1°5593
Do. 13. 1°5281 1°52788 1°5279
Do. 9. 1°5296 1°52945 1°5296
Oil of turpentine.| 1°4'744 1°47444 | 1°4746
Solution of potash. 1°4028 1°40270 1°4029
Water. 1°3336 1°33346 1°3333

I shall not here enter on any detailed remarks or compari-
sons of the results exhibited in this table. From it the reader
will be enabled to form a correct judgement of the degree in
which the approximate method is comparable with the exact ;
at least for media of no higher dispersive power than those
examined by Fraunhofer. Meanwhile we may just observe,
that the results here given by the exact formula are invariably
a little in defect compared with those of observation; whereas
the approximate numbers are sometimes in defect and some-
times in excess. To this circumstance, and some further
investigations connected with it, I shall recur in a future

communication.

—<—<_—_—=—

In the last Number (p. 113) 1 alluded to the calculations of
M. Rudberg. It may be worth while to observe that such a
formula as that which he adopted empirically, may give results
nearly coinciding with those of the formula derived from
theory which I have used, as will appear by the following con-
siderations.

M. Rudberg’s formula, in my notation, becomes

ie = a ae),

be

1
Now (writing @ gaan a'), let us suppose a quantity H! so
assumed that we have

or; atx = H'(1-=5);

Rev. Mr. Whewell’s Reply to the Quarterly Review. 211
then (writing H! ¢’-> =H) we shall have
Sagey 1, a1) a2. ]
{=H [ 1 (m=1) tp ae.
This may obviously coincide with approximate development
1 Black ae

especially if we confine ourselves to the first two terms,
2,

(which is usually sufficient,) making (m—1) = er

XLI. Remarks on a Note on a Pamphlet entitled ** Newton
and Flamsteed” in No. CX. of the Quarterly Review. By
the Rev. W. Wuewewt, M.A. F.R.S., Fellow and Tutor
of Trinity College, Cambridge.*

To the Editor of the Quarterly Review.
My dear Sir, Trinity College, Cambridge, Feb. 3, 1836.
HAVE just seen No. 110 of the Review; and I perceive
that the reviewer of Mr. Baily’s account of Flamsteed,
in No. 109, has done my remarks on his article the honour of
writing a note respecting them, which you have inserted.

As I do not see in this note any new arguments on the re-
viewer's side of our controversy, I do not conceive that I have
occasion to add much to what I have already said, for I pre-
sume your readers do not look for an answer to mere hard
words, A few additional remarks will, I think, enable com-
petent judges to decide between us.

I asserted, and assert, that Flamsteed never fully compre-
hended or accepted Newton’s theory ;—never understood the
difference between the Newtonian theory of the causes of the
celestial motions, and the empirical laws of phanomena which
he himself called theories;—in short, the difference between a
formula and an explanation—between the discovery of what
occurred, and the discovery why it occurred—between an ob-
server and a philosopher. I quoted a letter which proved this;
nor does the reviewer venture to deny the clear inference
which irresistibly follows from this quotation. But he takes
refuge in “ the whole tenour of the correspondence,” without
quoting a single passage. ‘To any one capable of understand-
ing the distinction which I have pointed out, the whole tenour
of the correspondence shows Flamsteed to have had no glimpse
of this difference. For example, he says (Account of Flam-

* From the 2nd edition of Mr. Whewell’s Pamphlet. See our last Num-
ber, p. 139—147.
2A2

212 The Rev. Mr. Whewell’s Remarks on a Note

steed, &c., p. 211,) of the theory, * Z call zt mine, because it
consists of my solar and lunar tables corrected by myself, and
shall own nothing of Mr. Newton’s labours till he fairly owns
what he has had from the Observatory ;” and (p. 214) he
says, that Newton “would needs question the observations
when they agreed not with his theories, or rather conceptions.”
The book is full of such expressions. The Edinburgh re-
viewer, wiser than his brother, has pointed out this.

When my opponent has produced any one passage which
shows that Flamsteed understood the difference between the
nature of his own labours and those of Newton, (which these
passages and many others prove he did not understand,) we
shall be able to appreciate his claims to use language like that
which he has applied to my opinions. ‘Till then, such ex-
pressions as ‘ audacious dictum,” and “we must beg our non-
undergraduate public to consider,” must, I think, pass for
bold words used to supply the lack of proofs.

I repeat also, that Flamsteed’s complaining that the English
nation was robbed, because Newton’s theory of comets was
confirmed by French observations, is another proof that Flam-
steed did not understand what the nature, interest, or value of
a true theory was.

With regard to the hard terms alleged by Flamsteed to
have been used by Newton, I should, I think, have conveyed
more exactly the impression which Flamsteed’s angry state-
ment leaves on calm consideration, by saying that it is proba-
ble that when Flamsteed had talked of the Royal Society as
the robbers of his property, Newton did, in some way, em-
ploy the term “puppy”; but that it is certain that this was
the hardest word which he was provoked to use; for it is
abundantly clear that if anything worse had been said, Flam-
steed was not in a temper, or of a character, to abstain from
recording it. ‘The reviewer’s argument amounts to this :—
that an angry man cannot exaggerate or misrepresent, because
a clergyman ought not to lie. I donot think this will avail him.

On the subject of the sealed packet, I will put the issue in
the form of a question. What does the reviewer take to have
been the purpose of depositing the observations in Newton’s
hands? My answer is simple. From Flamsteed’s known
irritability, it was thought necessary to require this deposit,
in order to secure the publication, in case Flamsteed should
refuse to proceed. The case provided for arrived: the remedy
was applied. I want to hear of any other interpretation of the
deposit.

The exclamatory way in which the reviewer disposes of the
account given by Arbuthnot of this step, appears to me rather

on * Newton and Flamsteed” zx the Quarterly Review. 213

tragical than logical. ‘The Queen’s command. What a
paltry, pitiful subterfuge! The Queen’s command! How often
is the name of royalty thus abused!” ‘The evidence that it
had been abused in this case is, I believe, only Flamsteed’s
opinion——** This I am persuaded was false” (p. 294)—which
I hold to be altogether insufficient, even if he had been an
uninterested and reasonable person.

The note quotes a passage of my remarks, in which I had
said that I left it to the reader to decide * whether the re-
viewer had not shown an extraordinary ignorance of that part
of scientific history,” &c. As I wrote with the wish of avoid-
ing anything offensive, I have once or twice since been dis-
posed to regret that I had not left this decision to the reader,
without saying that I had done so. I feel much less of this
regret after reading the reviewer’s acknowledgement respect-
ing the preface to the first edition of the Observations, that
‘* he certainly is ignorant of this preface ;” and after his speak-
ing of it as a want of candour to call it Halley’s, which no
person at all acquainted with the history of astronomy needs
to be informed. As to the statement made in this preface, I
need not inform those who have read my Remarks, that I did
not put it forward as unquestionable authority, but as the case
on one side, in opposition to the ex-parte statement made by
the reviewer on the other. ‘There is, however, this material
difference ;—that this statement of Halley’s was published to
the world, and challenged contradiction ; that adopted by the
reviewer is found in the moody soliloquies and querulous effu-
sions of a weak man, which did not see the light till a hundred
and thirty years later. As to Tlamsteed’s charges against
Halley’s edition, I can hardly suppose that the reviewer will
carry any unprejudiced reader with him when he adopts them;
though this proceeding is certainly in the general spirit of his
treatment of the subject.

I did not argue the question of right in my Remarks; but
I must now say that I am very far from assenting to the state-
ments on this subject which have been published. The ques-
tion of the kind of constraint which the nation has a right to
exercise over the publication of the astronomer royal’s Obser-
vations, I conceive to be avery difficult one: but Halley’s
statement that the Observatory had existed for thirty years
and that nothing had been published, is a strong primd facie
case; for it would be absurd to suppose that the Observer
was at liberty to lock up his observations for ever. What
would be the use of such an Observatory? or the meaning of
its having visitors? I must observe here that the reviewer has,
very unwarrantably, transformed the statement that nothing

214 ‘The Rev. Mr. Whewell’s Remarks on a Note

was published, into a charge that nothing was done. The
complaint was, that though much was done, nobody but the
observer could profit. by it.

I do not think it a reasonable infliction either on the reader
or the writer, that a discussion of the character of one man
should ramify into controversies on the merits of several others;
and therefore I shall say as little as possible respecting Hal-
ley and Whiston. Halley, an eminent and vigorous philoso-
pher, who devoted himself to science in the most liberal and
useful manner during a long life, I hope to see vindicated, by
some one acquainted with the history of those times, from the
aspersions which the childish spleen and gall of an irritated
rival threw upon him, and which have been so strangely and
precipitately adopted by men of the present day. I lament
his or any one’s errors; but when the reviewer reminds us of
the exclusion of Halley from the Savilian professorship on
the ground of his want of religion, we may, perhaps, allow
ourselves to hope that his subsequent election to the office im-
plies that such unhappy opinions had been discarded. The
charges of ignorance and immoral conduct are utterly at va-
riance with all we know of him; and rest on nothing but
Flamsteed’s extravagant prejudices and passions servilely
adopted by the reviewer. The friend of Newton, the favoured
servant of King William, Queen Anne, Queen Caroline, to
whom the offer was made of being appointed preceptor to the
Duke of Cumberland, was never by any other person accused
of want of respectability: and the man whom Lalande termed
the greatest of English astronomers, and whom the severe-
judging Delambre calls one of the most eminent men of sci-
ence that Europe has produced, can suffer little from Flam-
steed’s disparagement of his knowledge.

I hold Whiston’s testimony to be of small value (not that
he himself was a worthless person, as the reviewer takes the
liberty of misquoting me), from the extraordinary inconsistency,
prejudice, and self-conceit, which I find in his memoirs of
himself. That he had some mathematical knowledge is little
to the purpose ; though, even in such subjects, I suppose the
reviewer is not prepared to admire the judgement which led
him to recommend the scheme of finding the longitude by
having ships moored all over the surface of the ocean, each to
fire a gun at midnight, so as to be heard and seen at any place.

The reviewer states that Halley also kept his observations
of the moon long unpublished, in order to have a chance of
obtaining the reward for the longitude; and asks, ** What does
Mr. Whewell think of private property now?” To which I
answer, that I think of Halley’s property as I think of Flam-

on * Newton and Flamsteed” in the Quarterly Review. 215

steed’s. Halley did publish, and with dispatch, his other ob-
servations. I have never either defended or blamed his hold-
ing back the lunar observations ; but I may observe that the
crisis which gave the peculiar importance to the publication
of Flamsteed’s was past; and I do not think Halley’s motive
at all reprehensible. In all such cases it is difficult to decide
what constraint may be applied so as to produce publication.
There may be a fault of procrastination and fastidiousness,
which was Flamsteed’s. The attempt to expedite publication
in the manner which may be most advantageous to astronomy
js meritorious; and this merit was Halley’s and Newton’s.
Whether in pursuit of this object they went beyond the limits
which it is so difficult to define, I do not pronounce; but I
am sure that Flamsteed was no judge of those limits; and his
evidence is so far damaged by his circumstances and charac-
ter, that it hardly helps us in deciding the point.

When you reviewers condescend to controversy, you have
an overwhelming advantage in being advocate and judge at
the same time. I presume it is in a momentary usurpation of
the latter capacity that my opponent calls my pamphlet
“rash,” “unworthy,” &c. And when, moreover, to the cir-
culation and authority of the Quarterly, you add the rapid
reply of a monthly periodical, as in the present case, a poor
pamphleteer has no chance of being heard in opposition to
you. I shall therefore take the vehicle nearest at hand for
this letter, and send it to the Cambridge paper; by which
means it may, I hope, come to the knowledge of several of
those who care most about the question.

Believe me, my dear Sir, yours very faithfully,
W. WHEWELL.

To the Editor of the Cambridge Chronicle.
Sir,

I shall be much obliged by your publishing this letter as a
postscript to that addressed to the editor of the Quarterly
Review, which you did me the favour of inserting in last week’s
Chronicle.

Some of my friends, feeling that strong interest in the fair
fame of Newton, which those cannot fail to feel who love to
contemplate the union of intellectual and, moral excellence,
have expressed regret at my not having answered the charge
that Newton neglected to acknowledge his obligation to Flam-
steed for the observations by which the numerical elements of
the lunar theory were determined; and that in the second edi-
tion of the Principia he erased the acknowledgement he had

216 ~- The Rev. Mr. Whewell’s Remarks on a Note

made in the first. I had passed over this point, as not bear-
ing materially on the dispute respecting the publication of
Flamsteed’s observations, which appears to have attracted the
largest share of the notice of the public; and with a view of
abridging, as much as justice would permit, this unprofitable
discussion of the errors and weaknesses of those whom we
have been accustomed to admire: but a few words on the
subject just mentioned may serve to show how much of mistake
there is in such statements.

That the Newtonian lunar theory was published the second
time without any acknowledgement of what it owed to Flam-
steed, is not true. Newton’s “Theory of the Moon,” on its
first appearance after the use of Flamsteed’s observations, and
on the only occasion (so far as I know) when it was published
with that title, was inserted in David Gregory’s Astronomia
Physice et Geometrice Elementa, printed in 1702. It is there
stated (p. 332) that the illustrious author had made the calcu-
lations agree very nearly with the phznomena, “ as he had
proved by very many places of the moon observed by the ce-
lebrated Mr. Flamsteed.” And the elements of the theory
are there by Newton referred to Greenwich. With this book,
Flamsteed was on various accounts much discontented. One
great reason was, that Gregory had said, “ ‘The most solid
walls, and even rocks and mountains, are not absolutely
steady ;” ‘ This,” says Flamsteed, “is a‘fling at my wall-arc.”
(Flamsteed, p. 204.) But I do not see that he here complains.
of any omission of his name in the Lunar Theory. Newton
had previously communicated his theory to Flamsteed, in the
shape in which the observer could understand and use it
(Flamsteed, p. 72); and though Flamsteed speaks contemp-
tuously and disparagingly of it, he employed it in constructing
lunar tables, which he called a Theory. It is of this that he
says, a little before the publication of Gregory’s work, (p. 211,)
‘‘ T call it mine, and shall own nothing of Mr. Newton’s la-
bours, till he fairly owns what he has had from the Observa-
tory.” ‘The obligations of the theory of universal gravitation
to Flamsteed, were of the same nature as its obligations to
Tycho Brahe, who believed that the sun went round the earth.
The observations were highly useful; but it would have been
an absurd perversion of the truth to have called the observer
one of the authors of the theory. Yet it is probable that no-
thing less than this, and probably not this, would have satis-
fied the discontented and morbid mind of Flamsteed. "What
was stated in Gregory’s book was just; and I do not see
what more could have been briefly said.

By the time of the publication of the second edition of the

on * Newton and Flamsteed” in the Quarterly Review. 217

Principia in 1713, (the year before the sacrifice to Heavenly
Truth), the impossibility of noticing Flamsteed in any man-
ner which would not disgust and irritate him, must have been
very clear. Newton appears therefore only to have acted with
common prudence and forbearance in avoiding such notice as
much as possible. Flamsteed is not quoted as authority for
the Lunar Theory, of which he rejected a great part. (See
Account of Flamsteed, pp. 304, 305, 309.) His observations
of the comet are quoted as the best. In several other points,
as the observations of the satellites of Jupiter, Newton refers
to published observations of other astronomers, instead of the
private communications of Flamsteed. It was proper to rea-
son upon published rather than upon unpublished observa-
tions; and the terms on which Flamsteed had put himself
with Newton were probably felt by the great philosopher to
be such as rendered it undesirable to make use of the private
letters of his perverse correspondent.

So far as the published letters of Flamsteed prove anything,
they show, that not only he did not feel himself injured by
not being mentioned in those parts of the second edition of
the Principia which refer to the moon, but that he entertained
such an opinion of the work as would have made him angry
at being so introduced. Thus, soon after the publication, he
says, (p. 305,) ** I think his new Principia worse than the
old.” And (p. 309) he writes to his friend Abraham Sharp,
«JT have determined to lay these crotchets of Sir Isaac New-
ton wholly aside; and I think if you purchase not the new
edition of his book [of which the price was 18s.] you will be
at least 17s. a saver by it; for I know not whether all the
alterations and additions be worth 12d.”

So much for the wrong done to Flamsteed by not being
sufficiently mentioned in the second edition of the Principia.
I have been told also that I ought to have noticed more par-
ticularly some of the extravagant expressions of assumed au-
thority and intemperate accusation which occur in the note
in the Quarterly Review: but as these can affect only the
character of the anonymous reviewer, I do not see how it can
be worth while to make them the subject of remark.

I will again leave it to the reader to decide, after looking at
the passages I have just produced, whether the writer of the
note, in appealing to “the whole tenour of the book,” as
proving that Flamsteed comprehended and accepted Newton’s
Theory, was not asserting at random, and taking the chance
of the impression he might produce, without having read the
work which was under his review, or understanding the ques-
tion on which he undertook to pronounce.

218 Prof. Rigaud on a Note in the

I suppose that if the vilifier of Newton has nothing to sup-
port him but rhetoric of this kind, the admirers of that great
man will not feel any permanent inquietude ; and my sole ob-
ject will be answered.

I am, Sir, your very obedient servant,
Trinity College, Feb. 6, 1836. _ W. WHEWELL.

XLII. Observations on a Note respecting Mr. Whewell, which
is appended to No. CX. of the Quarterly Review. ByS. P.
Rieaup, Esq. M.A. F.R.S., Savilian Professor of Astronomy,
Ozford.

To the Editors of the Philosophical Magazine and Journal.

SIRs, Oxford.

Tue following remarks were, for the most part, drawn up
before I saw the letters which Mr. Whewell has printed in
the Cambridge Chronicle of the 6th and 13th of February*.
Some parts of what had been written were found, in conse-
quence, to be unnecessary ; but leaving these to his able de-
fence, I am still induced to offer the remainder to your con-
sideration. Irritation is so great an obstacle to the attainment
of truth, that I deeply regret the tone which the writer has
assumed. That, however, I leave to his better feelings; my
business is with his facts and his arguments.

S. P. Ricaup.
PRE reader is most probably acquainted with the Note in

question; it seems unnecessary, therefore, to occupy his
time with introductory explanations of the parts which have
been thought to require correction. ‘The topics, though ex-
amined separately, are taken nearly in the order which the
original suggested.

Whiston was an honest and laborious man, but very defi-
cient in judgement. As he advanced in life he became more
pertinacious in error; he had sacrificed the world to his sin-
cerity, and, conscious of moral rectitude in his purpose, he
persuaded himself that he must be equally right in his opinions.
Bishop Hare’s own character adds no weight to the senti-
ments which he may express on this subject, but the few words
which have been quoted from him are not contradictory to
what is here said. Sir Isaac Newton, therefore, may be equally
justified in his early patronage of his successor in the Lucasian
Professorship, and in afterwards shunning his society. ‘This
change Whiston was unwilling to consider as just; and in

* See the preceding article of our present Number.

Quarterly Review respecting Mr. Whewell. 219

speaking of the man whose friendship he had lost, he says in-
deed what he thinks, but his thoughts, which at best were
often inaccurate, were now warped by his feelings of disap-
pointment.

I have not the slightest wish to take in any way from what
may be justly due to Flamsteed ; on the contrary, I honour
his self-devotion to that department of science in which he was
qualified so eminently and so usefully to excel; I honour his
independence and noble application of his own property to
his great (and it ought to have been national) object; I re-
spect his religion, but I fear that I do not adopt so high a
view of it as some of his undiscriminating admirers. I do
not mean to express any doubts of his opinions on the great
truths of Revelation, or of his general intention to conform his
conduct to the dictates of Christianity; but his unhappy tem-
per, irritated by disease, was suffered to become ungovern-
able. ‘If any man seem to be religious and bridleth not his
tongue, but deceiveth his own heart,” the apostle has told us
the state to which he may be reduced. I presume to judge
no one or to pronounce that “his religion is vain”; but, with
every allowance for the weakness of human nature, I must
say, that professions of forgiveness too frequently repeated,
and constant assumption of the special favour of Heaven, are,
when unaccompanied by kind thoughts and mild language,
the sources of very painful impressions.

To enter fully into the character of Halley would require
more time and space than can now be assigned to it ; but there is
one point which must not be passed over. To call him a
“ self-convicted infidel ” is, to say the least, strong language,
which when applied to the mighty dead, should not have been
used without mature consideration. The authority, from which
it is derived, was probably Whiston’s account of the election
in 1691 to the Savilian Professorship. The application, that
Whiston makes of it to his own case, might have suggested
the possibility of some bias in the direction which he gives to
the story; and as the question is now about Halley’s own view
of his opinions, we have much better evidence ina letter which
he wrote on the 22nd of June, in the same year, to Mr. Abra-
ham Hill, which proves that, so far from submitting of neces-
sity to an examination, in which he was likely to bear himself,
as Whiston reports, with unbending defiance towards Bentley,
he courted the inquiry in confidence of being able to clear himself
from the charge which was brought against him. ‘The letter like-
wise supplies us with the definite nature of this charge ; for it
mentions a caveat having been entered against him till he could
show that he was “ not guilty of asserting the eternity of the

220 Prof. Rigaud, on Newton, Whiston,

world.” This objection necessarily* involved his being an
atheist, and not merely a sceptic as Whiston ‘says, which shows
again the inaccuracy of his relation. It may be from the
fault of a bad memory, it may be from a limited extent of
reading, but I can at this moment recall to my recollection
no one passage, in which Halley has published anything pro-
fane ; and I may add that in some disquisitions on the general
deluge, which he published in the Philosophical Transactions,
he treats the Scripture account with all due respect. ‘These
disquisitions seem also to supply a clue to the cause of the ca-
veat; for having reasoned on the dislocations visible on the
earth’s surface, he subjoined an explanation of his hypothesis,
because it was suggested to him that those changes might
rather have happened in times before the Mosaic creation, (when
a former world was possibly reduced to chaos, out of whose
ruins the present might be formed,) than at the period of the
Deluge. This, in the eyes of many religious persons, may
then have amounted to a heinous offence; but whether it did
so with justice may now be safely left to the determination of
Christian geologists. The passage immediately referred to
occurs indeed in the Philosophical Transactions for 1724; but
Halley had treated of the Deluge in the 190th number of the
same collection, which, having been published in 1687, makes
it not improbable that he may then, in discussing the subject
among his friends, have used the same topics, and have thus
raised the storm which burst on him in 1691. But to return
to the term originally objected to: it was proposed, in 1691,
to send in testimonials of Halley’s character to the electors of
the Savilian Professor; and the form, in one part, said that his
friends recommended him from their * own long experience
of his mathematical genius, probity, sobriety, and good life.”

* This, perhaps, should not be assumed as a necessary consequence, lest
injustice should be done to those philosophers, both heathen and Chris-
tian, who, salva pietate, have entertained the notion of the eternity of the
world as the coexistent effect of an Eternal Intelligent Cause ; the Stoics,
for instance, Volkelius, &c.

Writers on Natural Theology now considered as of the highest authority,
following the example set by Crellius, are, we believe, disposed to place
most reliance upon the arguments to be derived from the course of nature
daily presented to the view, as being of the greatest efficacy, both with or-
dinary minds and with those to whom abstruse questions respecting the
materia prima, &c, may have suggested themselves.

“Nunc id,” says Crellius, ‘quod tota Peripateticorum, imo et Platoni-
corum schola, non modo fatetur, sed et urget, probabimus, nempe res hujus
universi omnes finis gratid existere; sed ita, ut controversiam de materia
primd, queecunque tandem ea sit, non faciamus nostram.”—Crellius, De Deo
et ejus Attributis, cap. iii.,in which work he was assisted by Stanislaus Lubje-
niecius, a Polish nobleman, the author of the Theatrum Cometicum.—R. T.]

Halley, and Flamsteed, 221

This passage is copied from a paper in Halley’s own hand-
writing, and shows that ‘self-convicted” is the last term
which can with propriety be applied to him. I hope that I feel
as much as any man a deep abhorrence of irreligion, and I
would not say a word to palliate its baneful nature; but to
overload accusations of this kind with unsupported preju-
dice seems to me to be the surest way of destroying their
effect.

That anything should have induced Newton to use harsh
language to Flamsteed is sincerely to be deplored; but there
are circumstances not to be neglected which may be gathered
from Flamsteed’s own account of what passed on the 26th of
Octeber 1711. His ironical thanks and recommendation to
restraint of passion, were no soothers of irritation. While the
accusation of robbery was dwelt on, it must be remembered
that Newton was under the persuasion of Flamsteed having
*¢ called him an atheist”; that Flamsteed, when this was men-
tioned, left him, without the slightest notice, in error on so
grave a point; and though he denies that he had uttered it,
he does not deny that he had entertained the suspicion; for
he only adds, “I hope he is none.” If Newton, under such
provocation, had remained unmoved, he would have been not
merely (as he was) one of the first of men, but he must have
been more than man; if the mildness of his natural temper
had not wholly unfitted him for personal altercation, he never
could have used such an unappropriate appellation as ‘ puppy ’
—how he would have expressed himself if more familiar with
the Janguage of reproach, I am unwilling to inquire.

When Newton called for the catalogue of stars, ** It would
neither be prudent nor safe,” Flamsteed said, “to trust a copy
of them out of my own keeping. He [Newton] answered,
‘that I might put them into his hands sealed up; whereby I
understood they were to be so kept by him till I had finished
the whole, and was ready to print it.” Here then was no
** solemn pledge”; not even any express conditions or precise
explanation are said to have accompanied the delivery. Now
Newton’s undoubted object was to secure the publication of
the catalogue, and as Flamsteed had taken his own view for
himself, Newton may, on his side, have understood that the
precaution of the seal was only to make the papers “safe”
until the time came for printing them. There are difficulties
about the story of this seal being broken, for it is told (I do
not mean intentionally) without sufficient precision. Every
honest mind revolts against a breach of trust; but we ought to
be well convinced of the character of the act and of the crimi-
nality of the person against whom it is alleged, before we pour

222 Prof. Rigaud, on Newton, Whiston,

out our indignation against him. The description (in p. 294)
seems to refer to the packet which was put into Newton’s
hands in 1705, and in another place (No. 163) Flamsteed
says that the seal was broken when the catalogue was returned
to him in 1708; but neither in his personal narrative (p. 86)
nor in his letter to Sharp (No. 135), does he make any such
complaint as he probably would, if the circumstance had oc-
curred at that time. The sextant observations were com-
pletely printed in 1707, and the managers decided on the ex-
pediency of immediately proceeding with the catalogue; they
may, therefore, have then considered the time to have arrived
when it was necessary to open and examine the document;
but there are particulars which seem rather to indicate that
they had not broken the seal till a later period. Whether
they were right or wrong in the proposed arrangement of the
publication does not affect the question of the fact, and it is
clear that nearly four years having elapsed, during which they
could not overcome Flamsteed’s opposition to their intentions,
they determined to wait no longer for his concurrence. The
Queen’s order to proceed with the publication appears to have
been issued in the beginning of 1711, and this seems to be
the probable time when the seal was broken. It is inconceiv-
able that Newton would have pleaded the authority of the
Queen’s order for what had taken place in 1708; and if he
had, it is highly improbable that Flamsteed would have failed
to notice so obvious a contradiction. By comparing Nos. 100,
104, and 199, it may be seen that, when irritated, Flamsteed
could forget what he had written, and in the hurry of
vexation he has here made a confusion in his narrative. Surely,
therefore, it would be unjust, without more complete know-
ledge of particulars, tocondemn Sir Isaac Newton and all his
friends on such an accusation, which is neither explained nor
corroborated by any concurring evidence. In such a case it
would be more fair to judge of the story by his established
character, than to sacrifice his character for the establishment
of the story. One thing, however, may be fairly presumed,—
that the Queen’s order justified what was done; for Flamsteed
in his reflections does not appeal from it, but confines his
complaint to the authority not having been really obtained,
or not till after the offence had been committed, (which latter
supposition is introduced as if the first broader assertion was
immediately accompanied by some doubts of its accuracy).

In the reference to what Halley says on the thirty years of
Flamsteed’s life, at Greenwich, the writer would have done
well to have looked to the original. It is indeed said, in the
preface, that during that time “ nihil prodierat”—-and nothing

i

Halley, and Flamsteed. 223

had been published ; but, as Mr. Whewell had observed, it is
added immediately after, “tot annos non effluxisse otiosos,
schedasque Grenovicenses in haud modicam crevisse molem.”
The whole, therefore, together is a plain statement of an un-
deniable truth.

The work which is regularly done in the execution of any
employment belongs of course to the employer, and his hav-
ing made a hard bargain in no way affects his right. Any
one, therefore, engaged in a great scientific work, was entitled
to apply to the Astronomer Royal for assistance from his un-
published observations, when they had accumulated for years
and there was no immediate prospect of their publication. A
discretionary power certainly rested with the observer, but it
referred to the nature and object of the application, and whe-
ther, if not immediately sanctioned by the Crown, it was such
as to imply a fair presumption of the Royal approbation:
the power did not extend to an arbitrary refusal. Flam-
steed may be considered as obliging Newton whenever he
readily communicated his official labours to him, but the
soni part of what he specifically “worked for Sir Isaac

ewton” consisted in the reduction of his observations, an
operation, in which he appears to have persisted contrary to
the expressed wishes of Newton (No. 30).

«¢ The sacrifice to heavenly truth” was not a holocaust of
300 copies of the book, for 388 pages of each were retained
by Flamsteed, and form a part of the Ist vol. of the Historia
Celestis. The whole that was burnt was the title and pre-
face, with the catalogue, and 120 pages extracted from the
later observations—about one fourth of what had been printed
by the referees.

That 100/. per annum was too small a payment to the astro-
nomer royal does not admit of a doubt; but his office existed
long before the importance of it was rightly understood, and
Burstow was a Crownliving, which was given to Flamsteed by
Lord Keeper North to set him more at his ease. This is not
the manner in which the astronomer royal ought to be remu-
nerated for his services; but in those days it was probably
thought an easy method of saving the public money. This in
no degree diminishes the injustice of not supplying him with
what was necessary for the Observatory; and, although he
certainly looked to some return from the sale of his observa-
tion, this was a miscalculation of what the market was likely
to produce.

Newton, in 1691, (No. 14,) had said to Flamsteed, “ If you
and I live not long enough, Mr. Gregory and Mr. Halley are
young men.” The office of astronomer royal was a fair ob-

224 Prof. Rigaud, on a Note in the Quarterly Review.

ject of honourable ambition, but those who accuse Halley of
the endeavours to supplant his predecessor, are bound to bring
forward direct facts, not surmises, in support of the charge.
With such an object, it was the more disinterested in him to
hold that the salary ought not to be augmented. He may
have done so in Flamsteed’s time, but I am not acquainted
with the authority for it. I have always heard that the objec-
tion was made by him to Queen Caroline, when she visited
the Observatory, and expressed a wish for the inadequate
payment being increased. From a document in the British
Museum it is clear that this could not have taken place before
September 1729. Halley, then, for nearly ten years conti-
nued himself to receive only the original “ pitiful salary” ;
the report was erroneous, which Crosthwait heard, of his
having in 1728 got an addition of 100/. per annum (No.
279.); and after all, he only obtained the further pay of the rank
which he had held in the navy.

There are some particulars respecting Halley’s observations
which ought to be added to the writer’s account, because they
bear immediately on the present question. It was on the 2nd
of March 1727 that Sir Isaac Newton reminded the Council of
the Royal Society that they had neglected their duty by not
having of late demanded, in obedience to the Queen’s order,
the fair copy of the annual observations. We see, therefore,
that Newton’s earnestness on this point did not originate in
any personal feeling against Flamsteed, and the minute shows
that he took the opportunity of Halley’s being present to make
the representation. ‘The whole is given by Mr. Baily (in the
Memoirs of the Royal Astronomical Society, vol. viii. p. 188.),
and he adds, * It is worthy of remark, that this was the last
meeting of the Royal Society at which Sir Isaac Newton was
present, as he died on the 20th of the same month.” It is not
indeed improbable that his death was hastened by this exer-
tion of the good old man in the execution of what he consi-
dered to be a duty. Hearne says, in one of his memorandum
books, ‘Some time before he died, a great quarrel happened be-
tween him and Dr. Halley.......This ’tis thought so much
discomposed Sir Isaac as to hasten his end.” Sir David
Brewster, in his Life of Newton, has alluded (p. 339) to this
circumstance, but he does not seem to have noticed the time
to which it refers. Halley, it must be admitted, in this case
was wrong. His withholding the required documents and
taking up Flamsteed’s idea of the observations being private
property were possibly, after Newton’s death, never interfered
with; and by the tacit acquiescence of the Government, not
only the rights of the Crown were virtually abandoned, but the

Whiston, Halley, and the Quarterly Review. 2925

claims of the astronomer royal were confirmed by long-con-
tinued usage.

*,.* I have much regretted the line which has heen taken
by the Reviewers. The public mind will be made up on the
differences between Newton and Flamsteed, and after a time
this history will be left to the few who are curious about such
subjects; but while new, there was something exciting in it,
and it has been put prominently forward, while the British
Catalogue, as republished by Mr. Baily, has been noticed
with merely transient praise. Now this is certainly not the
least valuable part of a very valuable volume. It is a work
of useful and lasting’ reference for the astronomer, which pos-
sibly no one would have undertaken excepting the person to
whom we are indebted for it, and which no one could have
executed who had not, with the advantages of modern science,
been, like him, for years familiar with the Historia Celestis.

XLIII. On Whiston, Halley, and the Quarterly Reviewer of
the * Account of Flamsteed.” By A CorrEsPoNDENT.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN, Manchester, Feb. 20.
HE Note on Mr. Whewell in the late Quarterly Review
is sufficiently revolting on account of its coarseness, and
the insulting imputation on that gentleman of having pre-
sumed upon his official station in the University, and treated
the subject of Newton and Flamsteed as ifhe were palming his
opinions upon undergraduates. Now I leave it to the readers
of Mr. Whewell’s letter to judge if ever imputation could be
more unfounded, and if his letter be not altogether free from all
appearance of assumption of the authority either of his office
or (what is much more) of his high scientific reputation.

But what is still more reprehensible is the barefaced disin-
genuousness which the writer displays. What can be a more
palpable misrepresentation than that contained in the follow-
ing passage relating to Whiston: “ If, therefore, he was the
worthless, shallow person that Mr. Whewell would have us to
believe....”? Now what Mr. Whewell really says of Whiston
is, that his yudgement is worthless. What is this, but an attempt
to deceive the reader ?

Another instance of this utter want of principle is displayed
in the writer’s reviling Halley for the very same conduct

Third Series. Vol. 8. No. 46. March 1836. 2B

226 Whiston, Halley, and the Quarterly Review.

which he had in the preceding page eulogized in Whiston,
namely, that he would not dissemble his religious opinions.
¢ The secret history,” says he, “of the enmity against Whis-
ton, is his conscientious departure from the doctrine of the
‘Church of England, and his adoption of the principles of
Arianism.” While of Halley he says, “ Mr. Whewell cannot
be ignorant that Halley was a self-convicted infidel, and that
he lost an honourable and lucrative situation by being so;—and
therefore, it seems’ more than probable that Flamsteed was
‘disgusted with him.”
It must be evident to everybody that the opprobrious term
“ self-convicted” must have been meant to impute to Halley
a consciousness of guilt, of moral depravity*: and his devia=
tion from orthodoxy, whatever it was, and ingenuous acknow-
ledgement of it, are, to suit the purposes of detraction, stig+
matized as a disgraceful crime, while Whiston’s, in order to
make him an auxiliary, 1 is justified and even praised as **a con-
scientious departure.” Let us try the question by making the
‘terms change sides. Why did he not call Halley’s “a Y con
scientious departure,” and Whiston “a self-convicted Arian” ?
—evidently to serve the cause of falsehood by insinuating a
prejudice. As for the term infidel, we know how vaguely and
inconsiderately, and malignantly, it has often been used ;
and that Newton himself was even called an atheist by some
of his contemporaries}. ‘Che character and extent of the de-
viation of these distinguished men from any standard of opi-
nion is wholly another consideration: but the moral quality
of the fact of their entertaining and avowing their convictions
is the same. With regard to Halley, Whiston’ s account bears
direct testimony to his sincerity and disinterestedness.
I will only add, that the Note is, with regard to honesty, of

the same stamp with the article which it vainly attempts to
defend ; and remain, Gentlemen, yours, &c. C.S.

* Sirrah, ’tis conscience makes you squeak.
So saying, on the fox ke flies.
The self-convicted felon dies.—Gay’s Fables, ii. 1.

+ Even in our own time a venerable and pious divine and distinguished
naturalist has not escaped similar malignity from one who aspired to be a
competitor; see Phil. Mag. and Annals, N.S. vol. x. p. 373: and in the
Morning Chronicle, a journal pretending to great liberality, these philoso-
phers, who from their ascribing to the Creator the power of enduing mat-
ter with life and thought, are denominated materialists, have also lately
been stigmatized as atheists.

[ 297 J :

XLIV. An Abstract of a Memoir on Physical Geology ; with
a further Exposition of certain Points connected with the
Sulject. By W. Horxins, Esq., M.A., F.G.S., of St. Peter’s
College, Cambridge.*

JN a memoir entitled “ Researches in Physical Geology,”
lately printed for the Transactions of the Cambridge Phi-

losophical Society, I have endeavoured to develop, by reason-
ing founded on mechanical principles, and by mathematical
methods, the effects of an elevatory force acting simulta-
neously at every point beneath extensive portions of the crust
of the earth, in producing in it dislocations and elevations
such as we now recognise. I have not there, however, at-
tempted to give any exposition of the mechanical principles
on which the investigations are founded, beyond what was
necessary to make the subject intelligible to persons familiar
with investigations of a similar character ; but, with the hope
that the interest which the subject of elevations must always
possess in the estimation of the speculative geologist may
appertain in some measure to any new theoretical views re-
specting it, I have now been induced to attempt a somewhat
more detailed and popular exposition of the mechanical con-
siderations which have entered into my own investigations,
and which must in some measure, I conceive, enter into all
others on similar points possessing any claim to a demonstra-
tive character. I cannot expect to remove difficulties inhe-
rent in such investigations, and which must be felt to be con-
siderable even by those best prepared to enter upon them;
but if I should succeed in so far diminishing them as to ren-
der the subject more accessible by the only way in which, in
my Opinion, it can be successfully approached, my object will
be accomplished. What I have now written may be consi-
dered as an abstract of a considerable portion of my memoir,
with a somewhat more detailed exposition of several points
connected with the subject of it.

When natural phenomena, characterized by general laws,
have suggested to us a general cause to which they may be re-
ferred, our first object must be to investigate the consequences
of this cause acting under certain conditions, and to compare
our results with those deduced from observation. Observa-~
tion, however, unaided by theory, can rarely accomplish
more than to detect approximations, more or less accurate,
to those perfectly definite laws which the phenomena would

* Communicated by the Author.

2B2

228 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

accurately follow under the influence of the principal cause
alone to which they are referrible. The coincidence between
these perfectly definite laws and those deduced from our as-
sumed general cause, independently of perturbing ones, must
afford the strongest test of the truth of our assumption. The
strength of the evidence thus derived, will of course depend
in such cases upon the accuracy of the approximation to de-
finite laws in the observed phazenomena ; but it is important to
observe, that this first approximation must always be the most
important one, and that it must be made the instant we begin
to speculate on the causes of such phenomena as I have al-
luded to, if the slightest value is to attach to our speculations;
and also that accurate (or what is synonymous in all, or at
least in all but the simplest cases,) mathematical methods of
investigating the effects which would result from our assumed
general cause, are just as necessary in the case we are sup-
posing, as if the observed phenomena presented accurate co-
incidences with the general laws to which they only approxi-
mate.

These remarks (sufficiently trite perhaps) are made with
the view of meeting directly the vulgar objection of the use-
lessness of applying mathematical investigations to geological
problems. ‘To assert this is, in fact, equivalent to the asser-
tion that that branch of the science with which we are imme-
diately concerned presents no phzenomena characterized by
general laws, or referrible to a definite and simple cause.
Such however is not the case. The phenomena do distinctly
approximate to obvious geometrical laws, and there is a sim-
ple cause to which they may be referred, the effects of which
it has been my object in the memoir in question to investigate
on mechanical principles, in order that we may compare the
laws obtained from these results with those to which the ob-
served phenomena are found to approximate.

The phenomena with which we are chiefly concerned in
these investigations are those dislocations of the crust of the
globe, which we recognise more particularly in faults and
mineral veins, or rather in the narrow fissures in which what
is properly termed the mineral vein is deposited. ‘The latter
phenomena might, in fact, be almost entirely comprehended
in the former, since it is found very generally, where mineral
veins occur in stratified masses, that the strata are somewhat
higher on one side of the vein than the other. In general
this difference of level (not exceeding, perhaps, a few feet) is
not sufficient to be designated as a fault, though it sometimes
increases so much as to be considered such. In these cases
it would appear absurd to suppose that the fissure of the

Mr. Hopkins’s Abstract of his Memoir on Physical Geoiogy. 229

mineral vein and the fault are not to be referred to the same
mechanical origin, or that other veins in the same district
should not be referred to the same cause as such an one as that
just described, from which, except where the above-mentioned
difference of level becomes great, they differ in no respect.
It is also highly important to observe, that (as far as investi-
gation has yet proceeded,) where faults and mineral veins co-
exist in the same district, they follow, with reference to their
positions, precisely the same laws.

I do not mean, however, to maintain that all mineral veins
are necessarily to be referred to the same mechanical cause.
I conceive that some of the Cornish veins—those, for instance,
of St. Austle Moor—are clearly referrible to some cause quite
distinct from that in which the veins of our limestone districts
have originated. The latter possess, I believe, universally the
characters which lead us to regard them as having originated,
like faults, in dislocations produced by mechanical violence,
while the former are almost totally destitute of these charac-
ters. It would, therefore, be absurd to conclude that these
two classes of veins have necessarily had the same origin. It
is not, however, from d@ priori considerations that these points
are to be finally decided: but since the evidence of dislocation
afforded by a fault is independent of its vertical magnitude,
I cannot but regard the mineral veins of our limestone di-
stricts as indicative of dislocations in the masses in which
they exist, equally with the faults with which they are so fre-
quently associated. I therefore regard them in this point of
view; the correctness of our doing so must, of course, be ul-
timately tested by the harmony which may exist between our
theoretical deductions involving this hypothesis, and the phz-
nomena which these veins actually present to us.

The planes of these dislocations approximate, in the first
place, to verticality ; and, secondly, their horizontal directions
bear distinct relations to the general configuration of the
elevated district in which they exist. If there be a central
axis of elevation, the directions of dislocation are approxi-
mately parallel or perpendicular to it, as is the case in most
of our mining districts; and if there be a central point of ele-
vation, these directions diverge from it as a centre. Such
appears to be the case in Mount Etna, and the groups of the
Cantal and Mont Dor. The lake district in this country pro-
bably affords a similar instance.

These are the laws established by observation, so far as
it has yet extended. Many anomalous cases may possibly
exist, but they will not invalidate the conclusion, that, so far
as the phenomena are characterized by these laws, they are

230 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

attributable to the action of some general cause, at least as ex
tensive in its operation as the district throughout which the
phenomena are observed to follow the same law without
breach of continuity. This cause is assumed to be that which
naturally suggests itself to the mind of every geologist, viz. an
elevatory force acting simultaneously at every point of a por-
tion of the earth’s crust, of at least the extent just intimated,
and of any assigned thickness. It is manifest, that the eleva-
tion of this mass must produce in it extension, and consequent
tension, which, if of sufficient intensity, will cause those dis-
locations or fissures which we now recognise in the phzeno-
mena already alluded to. These fissures must, according to
this theory, be regarded as the primary phenomena, with
which all the other phzenomena of elevation, as faults, mineral
veins, anticlinal lines, &c., are connected as secondary ones.

I have carefully abstained in my memoir from any specula-
tions on the causes which might produce this elevatory force—
I merely assume its existence. It is easy, however, to con-
ceive such a force to act as above supposed, if we assume the
existence of a cavity beneath the elevated mass, either origi-
nally coextensive with it, or rendered so by the action of the
elevatory force itself. Any vapour or matter in a state of
fluidity from heat, forced into this cavity, or expanded there,
will produce the elevatory force which I assume to have acted.
This appears to be the simplest mode in which we can con-
ceive such a force to be produced; and if we choose to set
out from the more remote hypothesis of the earth’s having
been originally fluid, it might probably be shown that the
formation of cavities such as above supposed, would, under
simple conditions, be the necessary consequence of that pro-
cess of cooling by which we must then suppose the crust of
the globe to have assumed its present solidity. Instead, how-
ever, of assuming the existence of a cavity, we might suppose
a portion of the solid matter of the earth, at a certain depth
beneath its surface, to become by some means expanded, and
by its expansion to elevate the superincumbent mass. This
hypothesis, as far as my investigations are concerned, would
equally suffice, as, in fact, would any other by which we could
account for the simultaneous action of an elevatory force upon
a portion of the earth’s crust of sufficient extent. For many
reasons, however, independent of my immediate object, I
should not hesitate to reject this latter hypothesis as generally
insufficient to account for observed phzenomena, and as in-
volving serious physical difficulties. If we adopt the hypothesis
of internal cavities, we may observe that there is no reason
why we should not suppose them to exist, not only at differ-

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 23%

ent depths in different places, but also along the same vertical
line, so that one shall be placed under another. It might, L
conceive, be shown to be highly probable, if we should again
recur to the hypothesis of the original fluidity of the globe,
that the deeper cavities would in such case be the more ex-
tensive.

The immediate consequence of the elevatory force, as al-
ready remarked, will be to produce eatension, and consequent
tensions, in the elevated mass. Our first object must be to
determine the directions of these tensions, for the purpose of
ascertaining those of the resulting fissures. We shall after-
wards consider the influence of the constitution of the elevated
mass ; at present it is only necessary to regard it as admitting
of a certain small extension without rupturing.

I. For the greater simplicity let us first suppose the ele-
vated mass to be of indefinite length, of uniform depth, and
bounded laterally by two vertical parallel planes, beyond which
the disturbance does not extend. Let A B B! A! bea section of
the mass by a vertical plane perpendicular to the axis of ele-

vation, A C B originally coinciding with A B; and let us also
suppose that every such section is precisely similar and equal.
Then it is manifest that there can be no extension perpendi-
cular to these sections*, and that, consequently, the whole ex-
tension must lie in directions perpendicular to the axis of
elevation. Now let us conceive for a moment the elevated
mass to consist merely of a very thin continuous lamina of it,
ACB. Then it is evident that the extension, and therefore
the tension, at any point, as C, in the section, must be in the
direction T C 'T’ of a tangent to the curve line ABC. Let
us now conceive another lamina, similar to the first, but with-
out any adhesion to it, superposed upon it. It is clear that
its extension, and, therefore, its tension, must be precisely the
same as that of the first lamina, always supposing the original

* The hypothesis of indefinite length in the elevation is equivalent to
that of its being terminated by sections equal and similar to the one de-
scribed in the text, so far as relates to’ the absence of longitudinal ex-
tension.

232 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

unextended dimensions of each to have been the same.
Again, suppose a third lamina superimposed in the same
manner, and then a fourth, and so on, till a mass of any as-
signed thickness shall have been thus composed. It will then
follow, from what has been shown, that the tension at any
point c of the mass in this state must lie in the plane of the
section, and in the direction to the tangent of the curve-line
acb, formed by the intersection of the vertical plane of the
section with the lamina in which the point ¢ may be situated.

The only difference between this hypothetical mass and
any proposed actual mass of the same form and dimensions,
will consist in this—that in the former there is no cohesion
whatever between the successive ]aminz of which we have
supposed it to be formed. If, however, our lamine should
be superposed on each other in their unextended state, and
made to cohere firmly together, (in which case the mass would
differ in no wise from any actual mass,) and then elevated to
the position represented in the diagram, it is easily seen that
the position of each point of the mass would be exactly the
same as in the hypothetical case above stated. Consequently,
the extension of any portion of the mass (and therefore the
tension) must be the same in the two cases. Hence then it
follows that if A BB! A! represent any actual elevated mass,
the direction of the tension at any point ¢ will be that of the
tangent line at that point as above described.

There is no difficulty in extending reasoning precisely si-
milar to the above to any more complicated form of the ele-
vated mass, of which the upper and lower surfaces were ori-
ginally parallel, and horizontal, and we shall arrive at this
conclusion.—J/ we conceive the mass, previous to its elevation,
to be composed of horizontal lamine (or thin strata) the direc-
tions of the tensions at any proposed point of the mass when ele-
vated but still unbroken, will lie in the tangent plane to the
curved surface formed by that originally horizontal lamina in
which the proposed point may be situated ; and the intensity of
the tensions will be the same*, in different lamine at points
similarly situated in each.

If the mass in its undisturbed position be not of uniform
depth, (2. ¢. if the upper and lower surfaces be not parallel,) the
above reasoning would not be accurately applicable. ‘The
case, however, we have considered may be taken as the stand-
ard one to which others will approximate with more or less
accuracy, particularly as physical reasons might be assigned

* There are causes why this should be only very approximately true,
(See Memoir, p, 42.)

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 233

why an extensive cavity within the earth should be nearly
horizontal. Adhering then to this case, it is manifest that the
extension of each component lamina of the mass will depend
on the form assumed by it when the mass is elevated, since its
boundaries, by hypothesis, remain immoveable. Consequently
the direction of the tension in the tangent plane before men-
tioned must also depend upon the form of the lamina. This
direction is not generally horizontal, but since it will usually
be nearly so, and will always determine the horizontal direc-
tion, or azimuth, of a vertical plane drawn through it, we shall
be understood when it may be convenient to speak of the ho-
rizontal tensions.

It is manifest then that the determinations of the directions
of the tangential tensions in the elevated mass, must in cases
such as the above be a purely geometrical problem, as may be
easily elucidated by a few instances. In the elevation already
described (of which the segment of a cylinder, by a plane
parallei to its axis, may be regarded as the approximate type,
and which may therefore be termed cylindrical) it has been
shown that this tension lies entirely in a vertical plane perpen-
dicular to the axis. If the elevation approximate to the form
of a cone (which may be conceived to be formed by the super-
position of similar conical shells), it may be shown*, that if
each lamina remain unbroken, the direction of the only ten-
sion will be parallel to the slant side of the cone, and will pass
through its axis; but that if a dislocation exist along the ver-
tical axis, the principal tension at any proposed point (parti-
cularly near the vertex) will be perpendicular to the vertical
plane passing through that point and the axis, there being
also another tension in that plane. If again the form of the
elevation should approximate to the segment of a sphere, there
will be two tensions at each point of the mass, one of which
will lie in the plane through the proposed point and the verti-
a axis of the elevation, the other being perpendicular to that

ane.

The above are some of the most simple forms which the
elevated masscan be conceived to assume; they may, how-
ever, be taken as the approximate types of many of the general
elevations which present themselves to our observation, con-
sidered independently of their local irregularities. When the
superficial boundary of the elevated mass is very irregular,
(particularly if the superficial extent be not very great,) the
directions of greatest extension, or of greatest tension, will be
very different in different points; and it may become very dif-

* See Memoir, p. 47.

234 Mr. Hopkins’s Abstract of his Memoir on Physical Geology:

ficult to calculate with any precision the resulting phenomena.

Cases however may easily be conceived without such diffi-

culty, though more complicated than the simple ones above,

alluded to. Suppose, for instance, recurring to ‘our hypothesis
of internal cavities, one cavity of great extent to exist at a cer-.
tain depth, and another smaller one within the mass above the;
former, and communicating with it, so that any fluid pressure
acting in the lower should be communicated immediately to
the upper one. ‘That portion of the elevated mass which lies
directly above the upper and smaller cavity, may manifestly
be subjected simultaneously to the tension impressed upon
the whole mass from the action of the elevatory force in the
larger cavity, and to that produced by the partial elevation
above the smaller one. ‘These two sets of tensions may be
conceived to be superimposed the one on the other, in the
same manner as any two sets of forces in equilibrium may be
so superimposed *. ‘Their intensities and directions will de-
pend on the forms of the general and partial elevations re-
spectively. ‘Thus we may have a partial elevation of which
a cone or segment of a sphere should be the approximate
type, superimposed upon a general one of which the type
should be the segment of a cylinder. Other combinations
might be formed in a similar manner.

Should it appear preferable to consider the subject inde-
pendently of the hypothesis of internal cavities, we have only,
to conceive our partial elevations to be produced by a more
intense action of the elevatory force at those points. As re-

ards the resulting state of tension, it is perfectly immaterial
which hypothesis we adopt.

The states of tension above described refer to the mass in its
elevated but unbroken state, z.e. previously to the formation
of those fissures which must of course be formed when the
tension shall become greater than the cohesive power of the
mass. ‘The tension will begin to be produced at the instant
the act of elevation commences, and will increase till it ac-
quires the intensity just mentioned. Z7zme will be necessary
for this, but it may possibly be so short as to give to the ac-
tion of the elevatory force the character of an impulsive action,
which would probably produce the most irregular phzeno-
mena, and such as would be altogether without the sphere of
calculation. I exclude therefore the hypothesis of this kind
of action, not as involving in itself any manifest improbability,
but as inconsistent with the existence of distinct approxima-

* One of these sets of tensions may possibly modify the other, but in

a general explanation, or in a first approximate calculation, this modifica-
tion may be neglected.

a

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 285

tions to general laws in the resulting phenomena. It would:
appear probable however that the time above mentioned will
be short, and I therefore assume it to be so, and that conse-
quently the tensions increase rapidly but continuously from
zero to that degree of intensity which is necessary to over-
come the cohesive power of the elevated mass. This assump-
tion has also the advantage of facilitating some parts of the
mathematical investigation*.

It will, perhaps, be somewhat more convenient for our
further investigations, if we conceive the tensions at different
points of one of our elevated, but still continuous and un-
broken, component laminz, transferred to corresponding
points of a plane laminat. For this purpose, imagine each
point of the curved lamina projected on a plane horizontal
one, and that the same tension exists at each point of the
latter, as at the point of the former, of which it is the projec-
tion; the direction of each tension in the horizontal lamina
being the projection upon it of that of the corresponding
tension in the curved one. Now one of our ultimate objects
will be, to determine the horizontal directions of the fissures
which must result in the elevated mass, when the tensions be-
come of sufficient intensity to produce them, and these direc-
tions may be considered as coinciding with those which would
be produced in our hypothetical horizontal lamina. Conse-
quently our investigation will be reduced to the determination
of these latter directions.

To elucidate this, suppose our general elevation to be such
as first mentioned above, or what I have termed cylindrical.
Its projection on a horizontal plane will be a parallelogram,

D EK

G F

represented by DE FG. Suppose also a partial elevation

* See Memoir, p. 21.

+ We may remark that the vertical elevation of the disturbed mass, in
the state above described, is always extremely small compared with its
horizontal extent.

236 The Rev. Dr. Robinson on the Aurora of

approximately spherical, superimposed upon the general one,
such that O shall be the projection of its vertical axis, and
the dotted circle that of the circumference of its base. Then
taking P as the projection of any proposed point in the par-
tial elevation, we must suppose applied there, first, a tension
(F) impressed on the mass generally perpendicular to D E;
secondly, a tension (/,) in a direction passing through O (see
p- 233); and thirdly, another tension /, perpendicular to P O.
From these data the directions of the fissure through P, when
the tensions become sufficient to produce it, must be deter-
mined. And here we may remark, that since one lamina of
our elevated mass will be similar to another, the tensions Ff,
and f;, will be very approximately the same for each; and
that consequently the direction of the fissure just mentioned
will equally determine the horizontal direction of the fissure
which shall pass through any point of which P is the projec-
tion. The extensibility of the mass being assumed to be
small, the intensities of the tensions F, f, f,, will be propor-
tional to the extension each would produce in the mass at P,
if it acted separately, or to the additional extension produced
by each when acting simultaneously. The accurate determi-
nation of these intensities would in most cases present great
difficulties. In general, however, it will be sufficient to con-
sider such tensions as f, and jf, (belonging to the partial ele-
vation) merely as forces producing modifications in the effects
of F, the nature of which can be determined with sufficient
accuracy for practical purposes.

[To be continued. ]

XLV. On the Aurora of November 18th, 1835. By the Rev.
T. R. Ropinson, D.D.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

ih R. STURGEON ’s notice of the aurora of § November
18th (not 16th as misprinted,) induces me to send you
the notes which I made of its appearance, as from his positive
statement ‘ that he saw no appearance of aurora to the south
of the zenith, though frequently looked for,” this seems to be
one of the very rare cases where auroral phenomena can be
proved to occur in a low region of the atmosphere. They
are as follows, the time being reduced to Greenwich.
‘Noy. 18. Sky strongly illuminated, but covered with
clouds till 9» 20", when two arches were visible, which broke

a

November 18th, 1835, as seen at Armagh. 237

suddenly into streamers. The largest was nearly straight,
but was met by another band of streamers making an angle
with it, thus:

a Cygni
TTT
may Tuc CU |
aLyre. # i Ty

ya

South of the zenith, however, there is a permanent arch, its
lower edge on a and y Orionis, and at the crest its altitude is
30° 13'*. Its upper edge passes through the Pleiades, but it
is broader there than at the vertex. This greater breadth
seems to be a fragment of another arch coalescing with the
principal one, and is fading away.

«9% 41™, The lower edge is on Aldebaran. The upper still
on the Pleiades.

<<‘ gh 48™, The arch suddenly becomes more luminous, The
altitude of its lower vertex is now 34°21’. A splendid yel-
low streamer darts along 30° of its upper edge, parallel to it,
(which is new to me, for all that Ihave noticed hitherto were
perpendicular to the arches or nearly so ;) with little intermis-
sion clouds and rain, but the arch when last seen unchanged.

© 108 35™, Clear. The arch has disappeared, but the whole
sky is covered with flashes which are brightest to the north.”

I may add, that the arch gave sufficient light to read the
seconds of my chronometer and note them down, so that it
seems impossible that Mr. Sturgeon could have failed to ob-
serve it, had it been visible at Woolwich. If this was not
the case, then probably the appearance which he describes
was the dissolution of my arch, and this meteor must have
been lower than any which I have seen. Perhaps some of
your correspondents may be able to afford additional infor-
mation.

Armagh Observatory, Feb. 5, 1836. T. R. Rozinson.

* These altitudes were taken by the sextant, bringing the visible hori-
zon’s image to the arch, and measuring its altitude (in this case 0° 51’) by
a circle in the daylight. ,

[ 238 J

XLVI. An Account of Experiments made at Constantinople
on Drummond’s Light, for the purpose of Lighthouse Illu-
mination in the Black Sea. By W. H. Bartow, Esgq., Civil
Engineer. Communicated by P. Barlow, Esq., F.B.S., in a
Letter to the Editors of the Lond. and Edinb. Philosophical
Magazine and Journal of Science.

GENTLEMEN, Royal Military Academy, Feb. 4, 1836.

I CAN hardly tell how far the following account of experi-

ments made on Drummond’s light at Constantinople may
be considered deserving a place in your scientific Journal: it
is to me highly interesting, on account of the ingenuity and
perseverance it displays in the pursuit of a scientific object,
under very difficult circumstances; and I think that it must
be gratifying to scientific men generally to know that the
Turks, hitherto so bigoted to old maxims and religious pre-
judices, are availing themselves of the most refined disco-
veries of modern philosophy. .

It may be well to state, as introductory to the following
letter, that Mr. W. H. Barlow has been a resident for some
time in Constantinople, for the purpose of constructing a brass-
foundery and boring-apparatus, upon a large scale, with a
view of remodelling the Turkish artillery; and thet on the re-
turn of Namik Pasha from this country, (who had examined
with a scrutinizing eye many of our manufacturing and scien-
tific establishments, ) Halil Pasha, the sultan’s son-in-law, sent
for Mr. Barlow, and spoke to him on the subject of restoring
some dilapidated lighthouses in the Black Sea, and requested
to know if he was acquainted with a very remarkable light
which was known in England under the name of Drum-
mond’s lamp. He was answered that he knew of it generally,
and that if he could find any description of it in any of his
books, he would furnish him with the particulars. Fortunately,
on referring to an ingenious Armenian physician, Dr. Zohrab,
who had studied at Edinburgh, he fell upon a number of the
Nautical Gazette in which an account was given of the light,
and on the ground of the information thus obtained the ex-
periments detailed in the following letter were undertaken. _

I am, dear Sirs, yours very truly,
Peter Bartow.

Letter to Peter Barlow, Esq.
Constantinople, Jan. 6, 1836.
** T have already informed you of my first experiments on
Drummond’s light, and the astonishment it produced in the

Experiments on Drummond’s Light made in Turkey. 239

‘Turks when it first shone forth in all its brilliancy. ‘ Mash-
‘allah allah gunez boo!’ was heard on all sides, and I must
‘acknowledge that my astonishment and delight were no less
when I first found my attempts successful, in which Dr. Zohrab
‘equally participated, neither of us having ever seen it in En-
‘gland. I promised you that on my return from examining and
‘reporting on the state of the lighthouses in the Black Sea,
I would give you a detailed account of my proceedings, a
promise which I now propose to redeem as far as the extent
of a letter will permit.

** When Halil Pasha first mentioned the Drummond’s light,
‘having searched my own library in vain for any description,
I applied to Dr. Zohrab, who, having studied in Edinburgh,
and being in the habit of reading English works, I thought
might possess the desired information ; and fortunately he had
a number of the Nautical Gazette in which was given several
particulars of the light, with drawings, and as we were reading
of its beauties, a sudden thought struck us of trying to make
it. I set to work that night, and made a drawing of the sim-
plest apparatus I could conceive capable of producing the de-
‘sired effect, which was as follows. In fig. 1, A and B are two
bladders, one containing
‘oxygen, the other hydro-
gen. C is the mixing-
box, to which they are
attached by being firmly
tied upon the two project-
ing pipes. In this box were placed about thirty pieces of
‘wire gauze, which, by the by, we were sadly at a loss to ob-
tain'till we accidentally fell upon two wire-gauze masks which
had been used at the last carnival; these were instantly cut
up and arranged in the mixing-box, at the upper end of which
we attached the small pipe and stopcock as in the figure.
The stopcock belonged to an apparatus of Dr. Zohrab’s, and
the small pipe wis made by an ingenious Armenian at Ga-
leta. Thus prepared, we filled the bladders with the proper
gases (after only one unsuccessful attempt), and a piece of lime
placed on a lump of clay was put before the jet: a board was
then placed on the bladders with a weight on it. We then
lighted the jet, and to our inexpressible joy a light instantly
burst forth so intense that it was impossible to look directly
at it. ‘This being accomplished, and our apparatus appearing
safe, I determined to exhibit the light itself to the Pasha, in-
stead of the drawing of it which I had promised him. The
astonishment and approbation were, as I have stated, very
great, and I was immediately dispatched to the Black Sea, to

240 Mr. W. H. Barlow’s Account of Experiments

examine and report on the state of the lighthouses. On my
return I was requested to make a larger and more complete
apparatus, in which I have succeeded to the full extent of my
expectation. This last light burns for an hour; it is described
below; but I must here first mention a circumstance attending
our first exhibition. After this was over, Dr. Zohrab and my-
self removed our apparatus, and there being still some gas
in the bladders, we lighted it again for our own amusement
in my drawing-office, when it exploded with great violence
while I was pressing the bladders with my hands. You re-
member the explosion of my gases in my little room at Rush-
grove Cottage, but that was nothing; this was so sharp that
T lost the sensibility of my right ear for nearly a month, and
the explosion forced pieces of the bladders quite through the
cloth of my trowsers; and yet, excepting my ear, I escaped
without injury.

In my large lamp it was necessary to have recourse to ga-
someters instead of bladders. ‘These, according to Drum-
mond’s description, were to act under a pressure of 30 inches
of water; and ‘our explosion jhad taught us that this pres-
sure must be very equable to prevent the mixing of the gases
in any great quantity. Many were the schemes I had, and
rejected, but at last I adopted the following :—A, fig. 2, is a
cylinder of tin two feet in diameter, and four feet six inches
high, closed at the bottom, and open at the top; B is another
cylinder, one foot nine inches in diameter, of the same height,
having a diaphragm at one foot eight inches from the bottom ;
this formed the hydrogen gasometer, and was used as follows:
From the bottom of the Jarger cylinder rose a pipe D, to the

Fig. 2.

ef
I m f ‘mn
Js
N
A
~S
\

va

Wy

height of one foot nine inches, and a small recess was made

on Drummond’s Light made at Constantinople. 241

an inch deep in the diaphragm of the inner cylinder to receive
its end; the inner cylinder, therefore, being placed within the
other, its edge rested on the bottom of the latter. To fill the
gasometer, the interior cylinder was taken out, and water
poured into the other to the level 7; the former was then re-
placed, the stopcock ¢ opened, and the air expelled till the
diaphragm reached the surface of the water; the gas was now
introduced at the stopcock, and the gasometer thereby raised :
twenty-seven inches of water were now poured into the part B,
which, together with the weight of the tin, made up the whole
pressure of thirty inches. This forced part of the water in D
up the sides of the vessel, and other water was added till
the external water rose to the level L, which is twenty-nine
inches above the top of the pipe; and consequently restored
the water in the lower part of the gasometer to its original
level 7. It is now evident that as many inches of gas as are
let off are supplied by the upper part descending ; and the sur-
face of the upper and lower diameter being the same, the level
of the water at 7 and L always remained the same, and con-
sequently the pressure. There is, moreover, very little friction,
and the action is soft and equal. The oxygen gasometer was
constructed in the same manner; but being only required to
hold half the quantity, its area of bottom was made only half
the former, the height being the same. The other parts are
easily comprehended: c’ is another cock; m, the mixing-box ;
S, S, its supports; p, the emission pipe; and ', the lime-ball.
Fig. 3 is a plan of the whole, showing both gasometers. The
mixing-box is made by soldering the pipe m into the outer
pipe , which has a diaphragm pierced with holes; the part of
the pipe m projecting through it has also holes round its side.

The lamp is lighted thus: the hydrogen being let on by

Fig. 3. Hydrogen.

its stopcock being opened, passes into m, and through the
Third Series, Vol. 8. No. 46. March 1836. 2C

242 Prof. Ritchie on Magnetic Attraction.

diaphragm d into c, and passes out through the pipes p p; this
is now lighted, and it burns with a red unsteady flame; then
the oxygen stopcock is turned gradually, when this gas passes
through the holes into c, where it mixes with the hydrogen,
and they come out in perfect union at the pipes p,p. The
hydrogen cock is now fully opened, and the other cock gra-
dually opened and adjusted till the lime-ball gives out its most
brilliant light, when the hydrogen flame entirely disappears.
The difficulties we encountered and the extraordinary shifts
we were put to would be very amusing to you, but they are
too long for a letter; suffice it to say, that in the end the ex-
periment succeeded beyond our most sanguine expectation.
The Pasha was delighted with its performance, and has taken
the apparatus to his palace. I have since exhibited to him
coal-gas light, which I managed much easier, and have drawn
out my estimates for this light and oil; but no doubt the latter
will be preferred, and I soon expect to be at work in putting
in proper repair the lighthouses of Fanaraki. I am anxi-
ously waiting your further description of Beale’s light, which
I will also show to the Pasha, who takes great interest in all

these matters. Witt Baweae

XLVII. Additional Remarks on the Law of Magnetic At-
tractions and Repulsions. By the Rev. Wit11aM RitcuHie,
LL.D. F.RS.*

S Mr. Fox still seems to think that the law of magnetic
attractions is inversely as the distance between the ends
of the attracting magnets, without any reference whatever to
their form, the following considerations will, I think, convince
him and every impartial inquirer that the supposed law has
no existence in nature.
Let two magnets be formed, of plate steel, into the annexed
figure, having the poles at P, P’, and consequently further
from the ends a, 6 than if the

bar were rectangular; then the _ }
attraction between those mag-
nets will follow very different P Pp’

Jaw from that which exists when

the bars are equally broad. The fact is, the supposed law
obtained by measuring from the ends of the magnet will change

with the length of the magnets, their form, and even with the
uniformity of the temper.

* Communicated by tke Author.

Mr. Woolhouse on the Theory of Gradients on Railways. 243

The law in question, then, being a function of so many va-
riable quantities, must be one of extreme complexity, perhaps
beyond the powers of the most refined analysis to unfold.

XLVIII. On the Theory of Gradients on Railways.
By Mr. W.S. B. Wootnouse.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

S Dr. Lardner and Mr. Barlow, in your Numbers for

* January and February, hold out conflicting opinions on
the theory of gradients on railways, and have left the subject
in a state more calculated to create doubts in the minds of the
less informed of your readers than to lead them towards the
formation of settled conclusions, perhaps you will favour me
with the insertion of a few words, by way of explanation, as
far as the philosophy of the question presents itself to my
mind. Mr. Barlow, without absolutely saying which of the
two solutions is wrong, though probably quite conclusive in
his own view of the matter, first states his objection to the
arithmetical results of the formula employed by Dr. Lardner
for the velocity, in certain cases, then gives an outline of his
principle of investigation, and finally expresses himself “ quite
content to leave the decision to those whose minds have not
already received a bias from preconceived notions of the
forces.” Whatever sentiments may prevail as to the compe-
tency of my opinions on such a subject, it will at least be
acknowledged that I possess the qualification of being free
from the bias here alluded to, and I am induced to hope that
your readers will, on this very ground, acquit me of any ima-
ginable interference in thus undertaking, voluntarily, the ex-
amination of a point that has already had the attention of such
distinguished individuals. By close and continued application
of particular opinions to particular subjects, it is indeed sur-
prising how they fix themselves in the mind, and become ulti-
mately, whether true or false, of almost a fundamental character,
But I donotconsider thisobservation to be applicable to the pre-
sent case. It is my wishto simplify and expose the truth as far as
Ican perceive it. Ido not, however, intrude the presentremarks
in elucidation of the subject without some degree of hesitation,
although quite free from apprehension as to their theoretical
soundness. ‘To many of your readers, who must be far from
satisfied with the present situation of the question, I never-
theless feel myself justified in submitting them.

2C2

244 Mr.W. S. B.Woolhouse on the Theory of

According to Dr. Lardner, the subject is “totally distinct
from the consideration of accelerating forces”; he considers
it to be essential that the velocities be continued uniform, and
therefore discards everything in the shape of an accelerating
force. Now, in order that such a theory may be sustained,
it is a well known elementary principle of forces, that the power
employed must be always precisely equal to the resistance, or
the amount of friction combined with the proper resolved effect
of gravity along the railway, observing, however, that in the
term friction, we must include the resistance to the motion ex-
perienced by the carriages, &c., in passing through the atmo-
sphere. We shall not here discuss the practicability of pre-
serving this exact balance between the forces at the various
changes of inclination ; nor shall we offer any serious objec-
tion to the principle that the friction is the same for all veloci-
ties, which has received the sanction of general practice,
though doubtless inaccurate, as far as regards the effect of the
atmosphere.

Continuing the notation of the preceding letters, we have ¢
for the moving power that will keep the load moving at a
uniform speed V along the level plane; ¢ + sin < for the moving
power to keep the load moving at the same uniform speed up
the inclined plane; and ¢ —sine for the moving power to sus-
tain the same uniform speed down the inclined plane. To
the truth of this there cannot be any doubt, if we assume, as
Dr. Lardner has done, that the friction ¢ is not altered by the
slight inclination of the plane. By following Dr. Lardner’s
reasoning, we are hence fairly led to the result that the same
amount of mechanical force will be expended in ascending
and descending the inclined plane, as in drawing the same
load backwards and forwards along the level plane of the same
length L.

Though Dr. Lardner is certainly justified in stating this
conclusion to be a plain result of first principles, it should at
the same time be remembered, that it rests solely on the hypo-
thesis that the power in each case is to be precisely adapted
to the amount of resistance, so as to preserve throughout the
the same uniform velocity V. This hypothesis has not been
admitted by Mr. Barlow, and it must necessarily fail in deter-
mining the effect produced by the deflection of a rail during
the transitory passage of the carriages. In this way, it appears
to me that the principle advocated by Dr. Lardner carries
with it a restriction that entirely unfits it for an objection to
what has been advanced by Mr. Barlow, in his Second Re-
port, addressed to the directors of the London and Birming-
ham Railway Company. On the other hand, * however, I can

Gradients on Railways. 245

only come to Mr. Barlow’s conclusion, that it is altogether
erroneous, both in theory and practice,” when the assumed
maintenance of uniform motion is objectionable, as it most
certainly is, in the case of the deflections of rails. Contenting
myself at present, then, with the opinion that the contending
parties thus view the question of power expended, on differ-
ent suppositions as to the way in which it is applied, I shall just
take a very brief sketch of the question of velocity, when the
motion is not assumed to continue the same through planes of
different inclinations.

Dr. Lardner supposes that in cases of uniform velocity, the
resistance into the velocity is constant, and on this assumption
deduces the equations stated by Mr. Barlow in page 97, viz.

: tV
(¢— sine) v=tV 0 ane
This assumed principle is, in my opinion, decidedly inaccurate,
more especially when it is contemplated that the carriages will
pass along with the uniform velocity so expressed. For uniform
motion can only be continued when the moving force continues
equalto the resistance; and assuming with Dr. Lardner that the
amount of friction is independent of the velocity, the speed will
in such a case be quite indeterminate ; or, in other words, the
power so applied will sustain uniformly any velocity that may
have been previously communicated. It the friction were really
independent of the velocity, while a moving force which exactly
balances the resistance would maintain uniformly any pre-
viously imparted motion, a moving force which exceeded the
resistance would transmit the carriages with a velocity con-
tinually accelerated, in conformity with what has been said by
Mr. Barlow: but as the portion of resistance arising from the
atmosphere at least, increases with the velocity, it is evident
that the resistance will gradually augment till it balances the
moving force, and so a uniform motion will eventually succeed.
If the carriages be so acted upon as to retain a uniform velo-
city v along a level plane, and with such velocity and moving
power they arrive at the upper end of, and proceed down, an
clined plane, the investigation given by Mr. Barlow, pages
98 —100, will be strictly accurate on two suppositions, viz. 1.
That the friction is independent of the velocity and inclination
of the plane; 2. That the action of the moving power is not
diminished by the increase of velocity. The former supposi-
tion is sanctioned by Dr. Lardner ; the latter, as Mr. Barlow
justly observes, if not true, will have the effect of giving the
velocity and space passed over, rather in excess of the truth, and
therefore the more favourable for a comparison with Dr. Lard-

246 Prof. Forbes on the Undulatory Theory of Heat, and

ner’s velocities, which are so much in excess. There can be
no doubt as to the inaccuracy of the preceding formula, from
which the last-mentioned velocities are calculated, as the prin-
ciple from which it is derived is not founded in theory.
Yours, &c.
February 20, 1836. W.S. B. Wootnouse.

XLIX. Note respecting the Undulatory Theory of Heat,
and on the Circular Polarization of Heat by Total Reflexion.
By James D. Forses, Esq., F.R.SS. L. § E., Professor of
Natural Philosophy in the University of Edinburgh.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

5 a subject so vast and so little explored as that of
radiant heat is undergoing investigation, it is hardly to
be expected either that experimentalists should abstain from
speculation, or, on the other hand, that such speculations
should be, in all cases, happily devised by their authors, or
fully apprehended by men of science generally. ‘The more
immediate results of M. Melloni’s researches as to the nature
of heat, do not seem to me to have been very philosophically
stated in such expositions of them as I have seen (at least in
English) ; but it is not of this that I at present mean to speak.
M. Melloni lately read a paper to the Academy of Sciences
stating certain objections to the undulatory theory of heat, on
which M. Ampere has lately published some ingenious specu-
lative views, but which (so far as I know) has received little
or no experimental support except that which I have given in
investigating the laws of its polarization. I wish to point out
what I conceive to be the present state of the subject, specu-
latively regarded, and to mention an additional discovery

which I have recently made in confirmation of these views.
The arguments which M. Melloni adduces tu prove that
light and heat are not the same modification of matter all
amount to this,—that they may be separated, often in the most
irregular and capricious manner, as when the action of a co-
loured medium absorbs certain rays of the luminous spectrum
and yet leaves unaltered the symmetry of the heating spec-
trum *. Such experiments, or many simpler ones, show that
heat is not light, but nothing more. If M. Ampere really
meant that the light of the solar spectrum zs the same thing
with the heat of the solar spectrum, nothing is easier than to
refute it, and I pointed out as distinctly as words can express
the fact, that light and heat are apparently separable in my

* L’ Institut (Journal), 23rd Dec. 18365.

the Circular Polarization of Heat by Total Reflexion. 247

paper on Polarization, Art. 25. “all our experiments point
to the first [conclusion], namely, that heat, though intimately
partaking of the nature of light, and accompanying it under
certain circumstances, is capable of almost complete separation
from it under others.” This is all that can be said as to the
matter of fact, and includes within it all the experiments quo-
ted in M. Melloni’s paper. For it will be found that the dif-
ficulties which beset the undulation theory of heat are all
addressed to our ignorance, not to our knowledge; they are
negative rather than positive; they refer entirely to dispersion
and absorption, the two great difficulties of the theory of
Young and Fresnel ; and it would be equally presumptuous
and unreasonable to expect to find at once in the new and
obscure subject of heat a solution of doubts which the far more
complete knowledge which we have of the subject of light has
been unable to resolve. The objection of the impermeability
of one substance to heat which is permeable to light, cannot
prove light and heat to be “ two essentially distinct modifica-
tions of the condition of the ethereal fluid *;” for the same
objection applies to different Aznds of light; a red glass is im-
permeable to yellow light, though it is perfectly transparent
for red light. To say that this conclusion results from the
phzenomena of partial absorption by coloured glasses, is taking
advantage of the total ignorance we are in with regard to lu-
minous absorption, as a sort of negative argument. The only
result is what I have already stated, (and I agree with M. Mel-
Joni that it is unanswerable,) that one and the same undulation
does not invariably impress the senses of sight and feeling at
once. ‘The great difficulty is this—to account for the equal
refrangibility of two waves having different properties. This
I conceive is the whole difficulty at present. Now I argue
that this cannot be urged as an wltimate difficulty until the
undulatory theory of dispersion is complete, which, notwith-
standing the most remarkable investigations and experiments
of Cauchy and Powell, I scarcely think can be admitted to be
accomplished. The difference between heat and light must be
such that the law of refrangibility shall either be independent of
it, or shall admit of one result corresponding to several values of
the distinguishing element. ‘Thus, if the length of the wave be
the sole distinction, the velocity in a dense medium must admit
of a single value for several values of the length; a very sup-
posable case, as such functions are frequently periodical +.

* TL’ Institut, p. 411, note.
_ + Though M. Cauchy’s expression contains a trigonometrical function,
it could not physically apply to this supposition,

248 Prof. Forbes on the Undulatory Theory of Heat.

Or the distinction may be founded on the extent of displacement
of the ethereal particles, or on a want of coincidence with the
law of force produced by displacement as commonly assumed,
or on a thousand other causes, on which I do not wish to
dwell because I see little advantage in presenting premature
hypotheses which a year or two may demolish. I cannot help
observing, however, in an experimental point of view, that if
Sir D. Brewster’s analysis of the solar spectrum he adopted,
we have a difficulty in the case of light identical with that in
the case of heat. It surely would have been unreasonable to
urge against that analysis that it could not be true, because it
is contrary to the assumption that colour depends on frequency
of vibration ;—and refrangibility solely upon the velocity of a
wave :—these are tne very points to be proved, and if we have
no breach of analogy between light and heat but on ground
still debateable as regards the former, the supporters of calo-
rific waves have little to tremble for.

Since the experiments of M. Matteucci respecting the in-
terference of calorific rays have been treated (and [ am in-
clined to think justly) as inconclusive, the proof of the polari-
zation and double refraction of heat is the only one to which
we can refer with any confidence as a basis of analogical rea-
soning. The phenomena of polarization and depolarization
of perfectly dark heat I have now succeeded in making as
obvious as most of the more ordinary experiments on trans-
mission, and I have lately succeeded in completing the ana-
logy in one case which seems to put the nature of the calorific
emanations beyond a doubt. Fresnel’s marvellous prediction
of the circular polarization of light by two internal total re-
flexions at certain angles, is justly appealed to as one of the
most conclusive evidences in favour of a theory which could
foresee so singular a result. By employing a rhomb of rock
salt I have obtained precisely analogous results in the case of
heat wholly unaccompanied by light*. ‘The loss is so trifling
in passing through this amazing substance (the discovery of
whose properties I hold to be the most valuable part of M.
Melloni’s valuable labours), and the total reflexion so far com-
plete, that this curious and complex experiment is almost as
easily tried as any of those in common polarization.

With such evidence before me I cannot for a moment doubt
that the waves (if such there be either in light or heat) pro-
duced by non-luminous hot bodies are identical in character
with those producing light, that is, that the vibrations are
transversal.

Before concluding, I beg to mention briefly a decisive ex-

* Communicated to the Royal Society of Edinburgh, Ist Feb. 1836.

Prof. Daubeny’s Reply to Dr. John Davy. —- 249

periment which I have made to show that conduction has no
influence in producing the appearance of polarization. For a
statement of the objection I refer to my note inserted in this
Journal for November last. It is thus obviated:

poe ewes
ee

T had a tin vessel constructed of the shape shown at A, which
had one surface a similar in size and position to the first or
polarizing plate used in my experiments, and of which the se-~
condary radiation to the analysing plate was supposed to pro-
duce the variations observed. ‘The analysing plate B was

laced between the thermo-electric pile P and the vessel A,
which was filled with bozling water, and which therefore pro-
duced on an enormously exaggerated scale the effects attributed
to my mica plate. The vessel A was then turned into the
various rectangular positions as regarded B, without any de-
cided difference of effect on the pile being observable; indeed,
if any, that effect indicated a maximum of heat reaching the
pile when the position of the surfaces was unsymmetrical, or
when in polarizing, it is least. This experiment was also re-
peated for the case of polarization by reflexion.

By a particular process (which I will take another oppor-
tunity of describing,) I have been enabled to prepare mica
plates, which, whilst they polarize more effectively than my
former ones, are of extreme tenuity, so that they are almost
incapable of becoming sensibly heated. With such plates I
can polarize about 50 per cent. of heat wholly unaccompanied
by light, and readily polarize the heat of boiling water.

I am, Gentlemen, yours truly,

Edinburgh, 12th Feb. 1836. James D. Forses.

ee

L. Reply to some Remarks contained in Dr. John Davy’s Life
of Sir Humphry Davy. By Cuartes Davseny, M.D.,
Professor of Chemistry, 5¢-5 Oxford.

Mr. Eprror,
N Dr. Davy’s lately published book, entitled “* Memoirs of
the Life of Sir Humphry Davy,” occurs a passage reflecting
on myself, on which I feel myself called upon to offer a few re-
marks.

250 Prof. Daubeny on Sir H. Davy’s Theory of Volcanos,

After noticing his brother’s change of opinion with respect
to the cause of volcanos, Dr. Davy proceeds as follows:

‘It would hardly be supposed, that my brother’s motives
for modifying his views respecting the nature of volcanic ac-
tion, as above stated, and for giving up in part a brilliant
hypothesis, could be misinterpreted, and referred to an un-
worthy feeling ; yet this, to my surprise, has been done, and
even by Dr. Charles Daubeny, Professor of Chemistry in the
University of Oxford. This Gentleman, in defending the
hypothesis. which he advocates, and which is precisely my
brother’s early hypothesis, comparing Sir H. Davy’s early
views with his later, says, ‘ The authority of Sir H. Davy may,
I conceive, on this occasion, be fairly pleaded against himself,
and the weight of his zpse dixit in the two latter years of his
life be viewed as counterbalanced by the contrary judgement
he had pronounced, apparently on the same evidence, at an
earlier period; neither is it inconsistent with what we know
of his character, to suppose that he should have acquired a
distaste for the theory in question, when he found it seized
upon and illustrated by an humble [humbler] class of in-
quirers.’ ”

* This I would remark is neither generous nor just, nor even
reasonable criticism. It is not generous to assign to unworthy
motives, a meritorious act; for so surely may be viewed the
relinquishing such an hypothesis by the author of it, when he
found it not sufficiently supported by facts. It is not just, be-
cause not true, that he merely gave his zpse dixit against his
early hypothesis ; in my brother’s observations on volcanos, as
I have mentioned, he assigned his reasons for so doing, con-
sisting chiefly in want of the positive evidence which he ex-
pected to have met with in examining into the phenomena of
active volcanos, provided the chemical theory were true. And
least of all, is the criticism reasonable: it is almost absurd to
suppose that my brother would relinquish his hypothesis be-
cause approved of and advocated by others. Dr. Daubeny
might as well have fancied that he would have changed his
views respecting chlorine, and the metallic bases of the fixed
alkalies, as soon as they were seized upon and illustrated by
an humbler class of inquirers.”

The asperity of the above remarks seems but little warrant-
ed by the occasion which has called them forth.

Had Dr. Davy been aware of the sentiments I have always
expressed relative to his deceased brother, he would have
acquitted me of any wish to depreciate his memory, and would
have felt that even in the absence of any other mode of ac-
counting for this change of opinion, I should have abstained

in Reply to Dr. John Davy. 251

from suggesting one which would have seriously disparaged
it.

But the whole amount of the charge (if charge it can be
called) which I had brought against Sir H. Davy, consisted
in attributing to him some degree of fickleness or caprice in the
abandonment of a preconceived opinion, apparently without
sufficient reason.

How far the motive suggested for this change of opinion
may be consistent with the character of the individual himself,
(which is now a matter of history, and not a fit subject for in-
discriminate panegyric,) will best be appreciated by those who
were most in his intimacy.

For my own part, as a warm admirer of his genius, though
gathering my impression of his sentiments and disposition
from public report; without any recollections from personal
acquaintance to correct the impressions thus received, but
with every disposition to extenuate the foibles of so great a
philosopher ; I shall sincerely rejoice, if the book now pub-
lished by his brother, a small part alone of which I have as yet
perused, should succeed in its proposed object of elevating the
personal reputation of the individual, and thus convince the
world that my interpretation of his conduct in this trivial par-
ticular has been erroneous.

Still, however, Dr. Davy must excuse me, if, from all that
has yet appeared, I persist in regarding his brother’s change
of opinion in this instance a matter rather of taste than of
judgement.

In the memoir on volcanos referred to, Sir Humphry di-
stinctly admits that his previous theory is fully competent to
explain all the phznomena*, although he concludes by
assigning a preference to the other explanation as recommend-
ed by greater simplicity ; a sentence which, as his biographer
Dr. Paris justly observes (Life, p. 247), must be admitted to
be rather equivocal. In his Consolations of a Philosopher he
is somewhat more explicit, yet even there the only reason he
assigns for preferring the theory of central heat is vagueenough,
being, as he thinks, ‘more agreeable to the analogies of things.”

Having, therefore, looked in vain in either of these records
of his sentiments for any attempt to show in what way “ this

* “ Assuming the hypothesis of the existence of such alloys of the metals
of the earths as may burn into lava in the interior, the whole phenomena
may be easily explained from the action of the water of the sea and air on
these metals; nor is there any fact, or any of the circumstances which I
have mentioned in the preceding part of this paper, which cannot be easily
explained, according to that hypothesis.””—Memoir on the Phenomena of
Volcanos, by Sir H. Davy, Phil. Trans. 1828. [or Phil. Mag. and Annals,
N.S. vol. iy. p. 85—94. Eprr.]

252 Prof. Daubeny on Sir H. Davy’s Theory of Volcanos,

simpler hypothesis” will account for the chemical phenomena
accompanying volcanic action, and Dr. Davy himself not
having supplied this desideratum, I cannot view his adoption
of it in any other light at present than as a matter of taste on
his part. Dr. Davy, indeed, makes his brother say, though I
have not yet lighted upon the passage in which this sentiment
occurs, that the chemical theory does not rest on sufficient
evidence.

This however, although a ground for scepticism as to the
truth of the one, would afford no reason for adopting the
other ; for granting that of two hypotheses both competent to
explain the facts, the simpler one ought to be preferred, no
competition surely can exist between them, when this can
be predicated only of one.

That the chemical theory will enable us to account for the
phenomena, has beenshown in the memoir which called forth
Dr. Davy’s animadversions, and since more fully elsewhere*,
and is admitted, as has been seen, in the fullest manner by
Sir Humphry in the very paper to which allusion is made.
Neither do I see the force of the negative evidence which Dr.
Davy has produced to impugn it, for he is too conversant
with volcanic operations to be ignorant that sulphuretted hy-
drogen is amongst its commonest products, and is too good a
chemist to admit the possibility of substances like potassium
or calcium in their unoxidized condition finding their way up-
wards in the midst of the steam, which always accompanies
volcanic ejections}. What, then, becomes of the objection, that
if the hypothesis were correct, inflammable gas might proba-
bly be detected issuing from the volcano, or that some pure
or uncombined alkaline or earthy inflammable basis might be
discovered entangled in the lava, when the former is seen to
be actually present, and the latter can so little be expected ?
And, whilst the presence of hydrogen, combined as it naturally
would be with the sulphur which we know to exist in such
situations, furnishes a striking confirmation of Sir Humphry
Davy’s original views, neither he, nor any other chemist, has
succeeded in accounting for it according to the opposite ones.

The same may be said of the sal ammoniac, the nitrogen,
and according to the simplest form of the hypothesis as ex~

* Encyclop. Metrop., art. GEoLocy.

+ This objection, at least, cannot have originated with Sir Humphry,
but must be the exclusive property of his brother, for in the memoir re-
ferred to we find Sir Humphry distinctly asserting, ‘‘ That the extreme
facility of oxidation belonging to these bodies, must prevent them from ever
being found in a pure combustible state in the products of volcanic erup-
tions.

in Reply to Dr. John Davy. 253

pounded by Cordier, even of the water and the muriatic acid,
which are noticed by Davy himself as issuing from the vol-
cano, whose phenomena he describes.

Whatever ground, therefore, may exist for his scepticism
on the subject, none certainly has been assigned for his
adoption of the rival hypothesis, which, without effecting the
object of explaining the facts, is saddled with assumptions
equally gratuitous ; the existence of the alkaline and earthy
bases in the interior of the earth, being not more unsupported
by direct evidence, than that of a central fluid mass; seeing
that the increasing temperature detected in descending into
the bowels of the earth, may be explained quite as well by
chemical processes carried on at the requisite depths, as by
the hypothesis of central fluidity.

I trust I have now said enough to justify my having stated
that Sir Humphry only gave his zpse dixif in support of his
new hypothesis, a point which I was at that time more parti-
cularly anxious to establish, from a wish to obtain for the
theory I had advocated an unprejudiced hearing, and being
well aware of the weight which the deliberate judgement of
such an authority as that of Sir H. Davy on a question of
science would obtain with most readers. Since that time the
favourable opinion expressed by the present as well as by the
late President of the Geological Society with respect to the
chemical theory, will have secured it a candid reception
amongst naturalists; whilst the authority of one of the most
distinguished of Sir Humphry Davy’s living cotemporaries
and rivals in science, Mons. Ampére, will vindicate its claim
to respect amongst chemical philosophers.—One more word
with respect to the reasonableness of imagining that Davy
might choose to abandon his former hypothesis without deli-
berate consideration.

In the first place, considering the numberless applications
of which his great discovery of the alkaline and earthy bases
admitted, it is not necessary to suppose that he would regard
this one with any peculiar favour. And indeed the only al-
lusion I find to it at all in any of his earlier publications con-
sists of four lines in a note appended to his Memoir on the
Decomposition of the Earths.

Secondly, the solid character of the discoveries on which
the reputation of Davy was based, would naturally make him
indifferent as to the fate of a theory resting on assumptions
which, whether probable or not, were such as could themselves
neither be substantiated nor set aside by direct experiment.

The higher, indeed, we estimate the fame of Sir H. Davy,
the less difficult will it appear to us to account for his aban-

254 Prof. Daubeny on Sir H. Davy’s Theory of Volcanos.

donment of his original views, and for his preference as a mat-
ter of taste for others which were calculated, from their very
vagueness, to allow full scope to that imagination, which, as
appears from his Consolations of a Philosopher, continued in
unimpaired vigour to the last. There is, therefore, no analogy
between the motives of his conduct in this case and in the
question with respect to the nature of chlorine, in which Sir
H. Davy might feel a just pride, as having recalled the scien-
tific world from theory to a simple expression of facts, and
thus corrected the logic of chemistry, in quite as great a de-
gree as he extended our knowledge of this particular class of
combinations.

It may be readily inferred from these remarks that I regard
the chemical theory of volcanos, which it has been my humble
endeavour to elucidate and to confirm, chiefly valuable by
erecting a standard to which volcanic operations may be com-
pared, and thus encouraging more minute attention to the
phznomena they present. ‘This the mere vague and general
statement of their originating in central heat is not so likely
to do, and hence it may perhaps be regretted, if the preference
for a simpler hypothesis, or the authority of great names,
should so prepossess the minds of men of science as to pre-
vent their entertaining the views I have advocated, and to
induce them to dismiss the subject as altogether beyond the
reach of probable conjecture *.

It is on this latter ground chiefly that I have chosen to ad-
dress you, for with respect to that part of the subject which
concerns myself I should have been content perhaps to leave
the question at issue to the candour of the public, and to the
impression which most persons will entertain, that I at least
can have no desire to attribute unworthy motives to Sir H.
Davy.

Oxford, Feb. 23, 1836.

* In Dr. Thomson’s Outlines of Mineralogy, Geology, and Mineral Ana-
lysis just published, I find this sentiment expressed, but the only objections
stated to the chemical theory are, Ist, The specific gravity of the earth;
Qndly, The nature of the elastic fluids emitted by volcanos. I regret, there-
fore, that the learned author, who has done me the honour of quoting and
commending the work on volcanos I published in 1826, had not zlso con-
sulted the article on Geology in the Encyclop. Metrop., to which I contri-
buted the portion relating to volcanos, as he would have there seen the first
objection fully, and I hope fairly, treated, and the latter shown to be quite
in aceordance with the theory.

The low specific gravity of the metals of the alkalies appears to operate
against the reception of the theory in the minds of many; yet if it can be
shown that the bases of those volcanic products which appear upon the
surface have collectively a greater specific gravity than the mass resulting
from their union with oxygen, I cannot see wherein the force of this objec-
tion resides.

[ 255 ]

LI. Proceedings of Learned Societies.

LINNZAN SOCIETY.

Jan. 19, J EAD, Descriptions of the species of Lacis found grow-
1836. ing in the River Essequibo, and of the fish called Pacou,
which feeds upon these plants. By Robert H. Schomburgh.

Feb. 2.—Read, Observations upon a supposed new species of Vero-
nica found in Staffordshire, in a letter to Mr. Sowerby ; by Mr. George
Luxford.

Also, descriptions of two species of the genus Pinus from the Hi-
malaya Alps. By Professor Don, Libr. L.S.

The first of these, which belongs to the group of spruce firs, has been
described and figured by Dr. Wallich, in the 3rd volume of his splendid
work on Indian plants, under the name of Pinus Smithiana, in honour
of the late eminent President of the Linnean Society. It is nearly
related to Pinus orientalis, a native of Armenia and the western parts
of Georgia, and has been cultivated for more than ten years in our
gardens, and was at first supposed to belong to the Indian cedar
(Pinus Deodara). Khutrow, Morinda, and Raga, are the names by
which it is known in its native mountains.

The second species belongs to the group of silver firs, and is nearly
allied to Pinus Webbiana, but is essentially distinguished from it by
its longer acutely bidentate leaves, of nearly the same colour on both
surfaces, by its shorter and thicker cones, with trapeziform scales, and
rounded notched bracteole. Dr. Wallich, who had neither seen
flowers nor fruit, has doubtfully referred it to Taxus, under the spe-
cific name of Lambertiana, in his Catalogue. Several travellers have
noticed the tree, but Mr. Royle appears to be the only one who has
been fortunate enough to meet with it in flower and fruit.

The author has noticed a remarkable peculiarity in the seeds of the
species belonging to this group, which consists in the rupture or se-
paration at the inner side of the external integument, leaving the
nucleus with its inner covering exposed at that part.

The following are the characters of these two species :

Sp. 1. Pinus Smirutana. Wail.

P. foliis solitariis compresso-tetragonis rectis subulatis pungentibus, strobilis

oblongis cylindraceis: squamis obovato-rotundatis coriaceis rigidis mar-
gine levissimis, antherarum cristé subrotunda erosé crenulata.

Sp. 2. Pinus Pinprow. Loyle MSS.
P. foliis bifariam versis linearibus planis utrinque concoloribus apice biden-
tatis, antherarum cristé bicorniculata, strobilis ovalibus: squamis trape-
zoideo-cordatis, bracteolis subrotundis emarginatis erosé crenulatis.

Feb. 16.—Read some observations on the Nephrodium rigidum.
By Professor Don, Libr.L.S.

For this valuable addition to the British Filices, we are indebted to
the Rev. W. T. Bree, who discovered it many years ago on Inglebo-
rough, and it has since been published in the Supplement to English
Botany. The British specimens accord entirely with foreign ones,
and with the accurate figure given by Schkuhr (Kryptog. Gew. t. 38.).

256 Proceedings of Learned Societies.

The author has proposed the following character of the species :

N. rigidum, fronde lanceolata bipinnata : pinnulis oblongis pinnatifidis: la-
ciniis arguté dentato-serratis: venulis inconspicuis, soris biseriatim
contiguis, indusio scarioso dilatato, stipite rhachique densé paleaceis.

The species ranks next to dilatatum and spinulosum, but differs
from both by its larger and more crowded sori, broader and more de-
pressed indusium, and by the stipes and rhachis being copiously clothed
with narrow ramentaceous scales as in Aspidium aculeatum. The more
delicate*fronds, with pinnatifid pinnule, having the lobes serrated with
sharp-pointed, incurved teeth, essentially distinguish it from Nephro-
dium Filix Mas, between which and spinulosum it appears to be inter-
mediate in its habit and characters.

Read also remarks on some varieties of Erica ciliaris and Tetraliz.
By Professor Don, Libr. L.S.

The extreme states of these two species are easily recognised at first
sight; but it must be admitted that varieties do occur in which the
characters of both appear blended. The normal form of ciliaris is
characterized by its flat, ovate, ternary leaves, elongated axis of its
inflorescence, oblong and slightly curved corollas, and naked anthers ;
and that of Tetralx by its quaternary, linear leaves, revolute at the
edges, capitate inflorescence, globular corollas, and aristate anthers.
Some of the varieties of ciliaris exhibited to the meeting, for which
the author was indebted to Mr. Hewett C. Watson, had the axis of
their inflorescence quite as much depressed as in Tetralizx, along with
the narrow quaternary leaves of that species. Another specimen,
clearly referrible to Tetralix, had the corolla nearly as long as in cilz-
aris. Another variety of Tetralix, lately discovered in Ireland, and
which by some botanists is regarded as constituting a distinct spe-
cies, has entirely the habit of ciliaris, but with the depressed inflo-
rescence, globular corollas and aristate anthers, of the former species ;
and it differs from both in the entire absence of the short pubescence
from the upper surface of the leaves.

The only permanent mark by which ciliaris and Tetralix can be
separated is by the absence or presence of the awn-like appendages at
the base of the anthers.

A comparison of Irish specimens of Gypsocallis mediterranea with
others containedin the Smithian Herbarium, shows that they agree in
every essential point; and although the two plants when grown to-
gether in a garden exhibit a somewhat different aspect, there cannot
remain any doubtas to their identity. G.carnea is readily distinguished
by the much greater length of its anthers and ovarium.

GIBRALTAR SCIENTIFIC SOCIETY.—NEW OBSERVATORY AT
CATANIA.

It is truly gratifying to see that activity in scientific pursuits is fast
spreading from Britain to her colonies. The institution at Quebec has
already distinguished itself by the publication of some able papers on
American geology, topography, and statistics ; and we now find that
a new society has started up at Gibraltar, which, we trust, may prove

Intelligence and Miscellaneous Articles. 257

as stable as the Rock itself, for the gradual changes in the members
of so respectable a garrison are ever likely to renew its spirit. We
are alluding to “ The Gibraltar Scientific Society,” of which Dr. Bur-
row, D.D., F.R.S., is the worthy president ; and we hope soon to
learn the names of the Council. One of that body, Captain W. H,
Shirreff, R.N., and a Fellow of the Royal Astronomical Society of
London, possesses a well-situated observatory, mounted with excellent
instruments, in the use of which he has long been expert. This gen-
tleman introduced two young officers of great merit to the December
meeting, Lieut. Graves and Lieut. Stanley, of the Navy, on which occa-
sion they were elected honorary members, as a mark of consideration for
their hydrographical labours in the Archipelago. We look forward to
the proceedings of this promising association with much interest.

The respected correspondent to whom we are indebted for the
foregoing notice adds the following :

“From a letter from Sig. Cacciatore, of Palermo, I find that the
University of Catania are about to build and equip an Observatory,
partly at their own expense, and partly at that of the King of Naples.
I have been applied to respecting instruments, &c.”

LII. Intelligence and Miscellaneous Articles.

ON NITRO-BENZIDE AND SULPHO-BENZIDE. BY E. MITSCHER-

LICH.
Nitro-ben- HEN hot and fuming nitric acid is gradually
zide.— added to benzine, action ensues, accompanied

with the evolution of heat; and a peculiar substance is formed, which
remains dissolved in the hot nitric acid; but when cooled it partly
separates, and floats on the surface. If the acid is then diluted with
water, this product falls to the bottom of the vessel. By washing,
and then distilling this substance, it may be obtained perfectly pure,
as a yellowish liquid, possessing a very sweet taste and peculiar
odour, somewhat between that of the volatile oil of almonds and oil
of cinnamon. Its specific gravity is 1-209 at 59° Fahr., it boils at
415-4° Fahr., and distills unchanged. At $7-4° Fahr. it solidifies,
affording acicular crystals.

This substance may be distilled unchanged with nitric acid. Di-
luted sulphuric acid does not act on it ; but when the concentrated
acid is boiled with it, it is decomposed, with the disengagement of
sulphurous acid gas, and the solution becomes highly coloured. When
heated with potassium, it detonates so violently as to break the ves-
sel. It is almost insoluble in water ; neither ether nor alcohol act
onit. The strong acids, such as the nitric and sulphuric, readily
dissolve it, better at a high than alow temperature. [t is composed of

12 volumes of the vapour of carbon, —
10 hydrogen,
2 azote,
4 . oxygen.
Third Series. Vol. 8. No. 45. March 1836. 2D

258 Intelligence and Miscellaneous Articles.

The specific gravity of the vapour is about 4:4,
1 volume of nitro-benzide is composed of
3 volumes carbon,
23 hydrogen,
4 azote,
1 oxygen.
The formation of nitro-benzide may be explained by supposing that
a volume of nitric acid gas combines with a volume of benzine,
whilst there separates } vol. of hydrogen and 4 vol. of oxygen.

Sulpho-benzide.—if benzine is mixed with anhydrous sulphuric
acid it is not decomposed, nor is any sulphurous acid gas liberated;
but a thick liquid, very soluble in water, is obtained, which, when
diluted with water, affords a crystalline substance equal to about
five or six parts for every 100 of benzine employed. This substance
is very slightly soluble in water, and may be purified by washing
with water. To completely purify it, it may be dissolved in
zther, filtered, the solution crystallized, and the crystals distilled.
At 212° Fahr. this substance melts, forming a transparent and colour-
less liquid, and boils at a temperature between the boiling-points of
sulphur and mercury. It is inodorous, insoluble in the alkalies ; but
soluble in the acids, where it separates the water. Heated with
sulphuric acid, it forms a particular acid, which forms a soluble com-
bination with barytes. The other acids do not alter it.

It is composed of 12 carbon,

10 hydrogen,
1 sulphur,
2 oxygen.

It thus appears that nitro- and sulpho-benzide are formed by the
union of nitric acid and sulphuric acid with benzine, and that during
this combination water is separated. It is owing to this circumstance
that the union of these substances is so stable as to resist the ordi-
nary methods of separating the acids. M. Mitscherlich, from the
analogy of these bodies with the amides, has proposed to call them
nitro- and sulpho-benzide.— Journal de Pharmacie, Juin 1835.

FORMATION OF ZTHER. BY M. MITSCHERLICH.

The decomposition of alcohol into ether and water is not inter-
esting merely by, the production of ether, but is especially so as an
example of a particular kind of decomposition, which cannot be so
well followed with any other substance, and which is manifested in the
formation of some important products, for example, in that of al-
cohol itself. M. Mitscherlich has endeavoured to elucidate the
phenomena of this decomposition by the following experiments :
Take a mixture of 100 parts of sulphuric acid, 20 of water, and 50
of anhydrous alcohol, and heat it gradually until its boiling-point
becomes 284° Fahrenheit. Alcohol is then allowed to fall gradually
into the vessel which contains the mixture, and the current is to be
so regulated that the heat of the mixture remains constantly at 284°.
If, for example, the operation be conducted with a mixture of six
ounces of sulphuric acid, one ounce and one fifth of water, and three

Intelligence and Miscellaneous Articles. 259

of alcohol, and if the density of each two ounces of preduct as it is
obtained be taken, it will be observed that this density passes gra-
dually from 0-780 to 0-788 and 0°798, and afterwards remains con-
stantly at the last-mentioned density, which is exactly that of the
alcohol employed. If the operation be properly conducted, an
unlimited quantity of alcohol may be converted into ether, provided
that the sulphuric acid does not change. ‘The distilled liquor is
formed of two distinct fluids ; the upper one is ether, containing a
little water and alcohol ; the lower one is water, with a little alcohol
and ether, Its weight is nearly equal to that of the alcohol employed,
and it is composed of

SEEDED ais oo dates 65
Alcohol). |5 plex. 442 18
Water 4,240.45 scr. 17—100

If into six ounces of concentrated sulphuric acid six ounces of
pure alcohol are suffered to flow gradually, a product of constant
density is not obtained until the sulphuric acid has taken its pro-
portion of water. Take, on the contrary, three ounces of sulphuric
acid and two ounces of water, and let alcohol be added, drop by drop ;
the first two ounces distilled are merely spirit, if wine of specific
gravity 0-926, containing scarcely a trace of ether. The density
decreases until the quantity of water of the sulphuric acid is re-
duced to its proportion, and the product of the distillation has ac-
quired the density of the alcohol.

If concentrated sulphuric acid be added to anhydrous alcohol in
excess, pure alcohol distils at first; but when the temperature
reaches nearly 260°, the first traces of ether begin to appear; the
production of ether is at its maximum between 284° and 302°.

It results, from the preceding observations, that alcohol, when in
contact with sulphuric acid, is converted into zther and water at a
temperature of about 284°. A great number of analogous deconi-
positions and combinations are known, which may be attributed en-
tirely to the influence of the contact of bodies. The most remark-
able example of this kind is that of the conversion of oxygenated
water into water and oxygen, by the slightest trace of the peroxide of
manganese and some other substances. The decomposition of sugar
into alcohol and carbonic acid, the oxidizement of alcohol when it is
changed into vinegar, are phenomena of the same kind ; and so also
is the conversion of starch and sugar by means of sulphuric acid.
M. Mitscherlich, observing that in the preparation of carburetted
hydrogen by means of sulphuric acid and alcohol water is formed
at the same time, attributes this decomposition of alcohol to the
influence of mere contact, and not to the affinity of sulphuric acid
for water.—Journal de Pharmacie, Juin 1835.

ON THE SEPARATION OF BARYTES AND STRONTIA.—BY
MR. J. D. SMITH.
The great analogy existing between the salts of barytes and strontia,
may render an observation on the difference of solubility in water of
2D2

260 Intelligence and Miscellaneous Articles.

their chromates worthy of notice ; and the more so, as it adds one
to the few methods already devised for the analysis of substances
containing both these earths. I had remarked some time before, that
when a solution of neutral chromate of potash was added to one of
muriate of strontia considerably diluted, no precipitation took place
until the mixed solutions were boiled, and. even then that a large
quantity of strontia was still held in solution; whilst, on the other
hand, the action of the neutral chromate of potash on a solution of
muriate of barytes was widely different ; for let the solution of barytes
be ever so largely diluted, yet chromate of potash invariably produced
precipitation ; so much so that wherever a sulphate was capable of
detecting this earth, chromate of potash also indicated its presence.
Wishing to examine some minerals supposed to contain both strontia
and barytes, it occurred to.me that the property possessed by a dilu-
ted solution of muriate of strontia of not precipitating with chromate
of potash, might be made available for analytical purposes. I there-
fore made a few experiments to ascertain the fitness of this salt as an
agent for separating the salts of these earths when dissolved in a large
quantity of water. These experiments at first did not afford very
exact results; for the precipi:ated chromate always appeared to in-
dicate rather more barytes than was originally taken: but tnis was
found to be owing to the chromate, like the sulphate of barytes, re-
quiring ignition before weighing, to expel a little water which obsti-
nately adheres to it when dried at low temperatures ; this error was
entirely obviated by heating the chromate to redness previous to
weighing it.

The cause of the error being thus ascertained, 20 grs. of carbonate
of strontia and 5 grs. of carbonate of barytes were dissolved in dilute
muriatic acid ; the solution wascarefully evaporated to dryness to expel
the excess of acid; the dry sait was redissolved in distilled water, and
the solution diluted to a pint and a half ; to this was added a dilute
solution of chromate of potash, made with transparent crystals, in
order to prevent the otherwise possible admixture of sulphate or
carbonate. After standing for a short time it was filtered, and the
chromate of barytes washed, dried, and ignited; weight 6°53 grs.=
5 grs. of carbonate. The solution and washings were then evapora-
ted to reduce the liquor to a smaller compass, and a solution of
sesquicarbonate of ammonia added, which precipitated carbonate of
strontia ; this when collected and dried weighed 19°19 grs.

Another experiment, in which the quantity of barytes exceeded that
of the strontia, was conducted in a similar manner, with the exception
of the employment of less water (2 pint) to dissolve the dry salt be-
fore the addition of the chromate of potash. In this case there were
obtained from 12 grs. of carbonate of barytes, and 8 grs. of car-
bonate of strontia, 15-8 grs. of chromate = 12°09 grs. of carbonate of
barytes, and 7°26 grs. of carbonate of strontia.

In both the above experiments it will be remarked that there is less
carbonate of strontia obtained than was originally taken: thisis owing
to strontia not being entirely precipitated by a solution of sesquicar-
bonate of ammonia ; for when this salt and muriate of strontia are

Intelligence and Miscellaneous Articles. 261

mixed, the former being in excess, the filtered liquor will become
slightly turbid on the addition of oxalate of ammonia, and stirring the
solution.

In the following experiment, in which 10 grs. of each carbonate were
taken, and oxalate substituted for sesquicarbonate of ammonia, the
results were chromate of barytes 13-04 grs. = 10 grs. of carbonate, and
11-9 grs. of oxalate = 10 grs. of carbonate of strontia ; thus showing
the superiority of oxalate of ammonia as a precipitant for strontia :
the only precaution necessary is to have the solution neutral.

Note. Pyroxylic spirit produces a more intense crimson flame witha
small quantity of muriate of strontia than alcohol does, and conse-
quently is of greater service as a test for recognising strontia when
occurring in minute quantity. f
St. Thomas's Hospital,

Feb. 1836.

COMPOSITION OF CARBONATE OF ZINC.—BY MR. J. D. SMITH.

When solutions of sesquicarbonate of ammonia and sulphate of
zinc are mixed, a white, bulky, and gelatinous precipitate is produced ;
this after repeated washings with hot water, by which carbonic acid
gas is plentifully evolved, falls as a white powder. 80 grs. of this
powder lost by ignition 22-5 grs., and 81) grs. dissolved in a counter-
poised bottle of dilute sulphuric acid, lost 12°5 grs. of carbonic acid.
From these experiments it appears that 80 grs. of this powder are
composed of 57°5 grs. oxide of zinc, 12°5 gts. of carbonic acid, and
10 grs. of water ; which numbers indicate a compound of 24 eqs. of
oxide of zinc, 2 eqs. of water, and | eq. of carbonic acid ; which may
be viewed either as a 2 carbonate of zinc with 4 eqs. of water, or as
1 eq. of hydrated subsesquicarbonate of zinc united to | eq. of hy-
drate of zinc. Its equivalent number being in former case 280, in
the latter 140,

or 24 eqs. of oxide of zinc 100
1 eq. of carbonic acid 22
2 eqs. of water...... 1S—140.
St. Thomas's Hospital,
Feb, 1836.

ON RIOLITE, A SUPPOSED BISELENIURET OF ZINC, AND HER-
RERITE, SUPPOSED TO BE CARBONATE OF TELLURIUM.—BY
PROFESSOR DEL RIO.

An account is given by Mr. Del Rio, in vol. iv. of the Phil. Mag.
and Ann., p. 113, of two new minerals found in Mexico ; one supposed
to be biseleniuret of zinc and sulphuret of mercury, which in honour
of Mr. Del Rio I have named Riolite ; the other, considered a bisele-
niuret of zinc and bisulphuret of mercury, | have named Culebrite,
from the place in which it occurs.

By the last mail I have received the following letter from Mr. Del
Rio relative to the first of these substances, and to another mineral,
supposed to be carbonate of tellurium, which I shall be obliged to the

262° Intelligence and Miscellaneous Articles.

editors of the Phil. Mag. and Journal of Science to insert in that

journal.
Feb. 18, 1836. H. J. Brooke.
“* Dear Sir, “ Mexico, November 14, 1835.

«<I have again examined the mineral you have been so kind as to
name Riolite, and have found it to be not a seleniuret of zinc, but a
native selenium ore with a variable mixture of sulphoseleniuret of mer-
cury, and seleniurets of cadmium and iron.

[ put in a retort 533 grs. which I washed to separate the carbonate
of lime: as some particles were attached to the sides of the retort,
I washed it down with some water, and at the moment many round
little lumps of selenium arose to the surface, which was covered with
a film of the same, proving that it was notcombined. There were sub-
limed by the distillation 38 grs. of selenium and 13 of mercury, which
was also amalgamated with selenium; and there remained in the re-
tort 10 grs. of a yellow and grey powder,

1. I treated the 10 grs. with muriatic acid, which dissolved the iron
and the cadmium, and the selenium was precipitated as a black pow-
der, which amounted to gr.

2. I precipitated the diluted solution (1.) with a small bar of zinc :
the grey and voluminous cadmium was easy to be distinguished from
the iron: both amounted to 13 gr.

3. The iron was dissolved in diluted muriatic acid, and the cadmium
in concentrated ; and the last was precipitated again with a bar of zinc
in a crucible of platinum, to which some cadmium was attached as a
silver white metal, and some was precipitated as a dark grey powder,
which deposited upon the charcoal at the blowpipe a reddish brown ring.

4. Together with the black powder (1.) I observed another preci-
pitate lighter in colour and heavier, which I separated by washing,
and treated with hydrochloromuriatic acid. All was dissolved imme-
diately, and red selenium arose to the surface, which was reduced
to selenious acid by the addition of nitric acid : there remained only
a melted globule of sulphur. At the same time some sulphate of lime
was precipitated, which amounted to 14 gr.

5. I precipitated the last solution with hydrosulphate of ammonia,
and I obtained 63 grs. of sulphuret of mercury.

6. The selenium (1.) was put in a little capsule over the lamp in
a dark corner of my room with some sulphuric acid, and gave many
small flashes of light on the surface of the liquid of the selenious acid
which sublimed; I smelled some sulphurous acid, and the decanted
solution precipitated red selenium with water ; the remaining solution
precipitated the same without water; and there was at the bottom
selenious acid as a white powder.

As the quantities of mercury and cadmium are variable, because I
found more in other specimens, I think this mineral is nothing else
than a mixture to which no formula can properly be applied.

In the beginning, when I thought it wasa seleniuret of a fixed base,
I treated it twice at the blowpipe with some iron and borax, and after
washing the charcoal I found both times the next day very small double

Meteorological Observations. 263

rhomboidal, oblique pyramids of seleniuret of iron of a dark grey co-
lour: the iron was dissolved in muriatic acid, and the black selenium
was precipitated.

I take profit of this opportunity to let you know that the Herrerite
is not a carbonate of tellurium, as it was announced by my pupil, but
of zinc and nickel, which gives to it the pretty pistachio and grass-
green colour: it contains also some cobalt ; and the apple-green,
fibrous, and very soft substance, which accompanies it, and I sup-
posed erroneously to be a species of the preceding, shows to be at the
blowpipe an arseniate of nickel.

As soon as I get some pieces of your Culebrite, I will examine it,
and give you notice.

ANDREA DEL Rio.

METEOROLOGICAL OBSERVATIONS FOR JANUARY 1836.

REMARKS.
Chiswick.— January 1. Snow. 2. Severe frost: slight snow at night.
3. Thawing: cloudy and fine. 4. Cloudy: stormy. 8. Hazy: fine.
9. Frosty. 10. Stormy, with some snow. 11. Overcast: heavy rain.
12. Sharp frost : clear and calm. 13. Frosty : cloudy. 14, Cloudy and
windy. 15. Heavy rain: clear and windy at night. 16,17. Clear and
frosty. 18.Cloudy and cold. 19. Fine. 20. Frosty haze: overcast.

21. Fine: clear. 22. Slight rain. 23. Boisterous. 24—26. Very fine.
27. Fine: stormy at night. 28. Fine: slight rain: windy. 29. Cloudy and
cold. 30.Clear and frosty: fine but cold. 31. Rain.

The plan which is followed in regard to the meteorological observations
made at the Garden of the Horticultural Society, is in accordance with
that recommended by Professor Daniell in his excellent Meteorological
Essays. A full account of the instruments employed is given by Mr. Booth
in yol. vii., p. 97, of the First Series of the Hort. Soc. Transactions. It will
be proper, however, to mention such circumstances as are connected with
the abstract which appears in the Phil. Mag. and Journal of Science.

The barometer is situated about fourteen feet above the mean level of
the Thames, at Chiswick. The observations are taken at 8 a.m., 1 p.m.,
and 10 .m. A correction is made for every observaticn for the capacity
of the cistern, the neutral point of the barometer, and the temperature of
the mercury; so that the column of mercury is reduced to that which, at
a temperature of 32°, would balance the atmosphere. The thermome-
ters indicating the mar. and min. of temperature are self-registering, and
of Rutherford’s construction; they are placed in an open space in the
Arboretum, and are protected from the rays of the sun by a sort of um-
brella of painted canvas. They are attached to the post which supports
the umbrella, a little below the level of the margin of the latter, and about
four feet from the ground.

The rain-gauge is made according to Mr. Howard’s directions, in his
work upon the Climate of London. ‘The quantity is registered every morn-
ing, when there is any, at 8 a.m. The direction of the wind is noted at
] P.M.

Boston.—January 1, 2. Cloudy. 3. Cloudy; rain p.m. 4. Cloudy.
5.Fine. 6. Cloudy. 7, 8. Fine. 9. Cloudy. 10. Cloudy: snow p.m.
11,12.Cloudy. 13.Fine. 14. Fine: snow melted: stormy night, with
rain, 15. Fine:rainr.m. 16,17. Fine. 18. Cloudy: rain p.m. 19. Fine.
20,21.Cloudy. 22, Cloudy: rain p.m. 23. Stormy. 24. Fine: rain p.m.
25.Foggy. 26.Cloudy. 27.Fine. 28. Fine: rain p.m. 29, Fine: snow
A.M. 30. Cloudy and stormy: snow a.M. 31. Snow.

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THE
LONDON ann EDINBURGH
PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]

APRIL 1836.

LIII. Cbservations upon the Habits of the Plecotus auritus,
or Long-eared Bat. By J. pr C. Sowersy, Esq., F.L.S.*

Axsour the beginning of August last, a living specimen

of the Long-eared Bat was given to my children, We
constructed a cage for him by covering a box with gauze and
making a round hole in the side fitted with a phial cork.
When he was awake we fed him with flies introduced through
this hole, and thus kept him for several weeks. The animal
soon became familiar, and immediately a fly was presented
alive at the hole he would run or fly from any part of the
cage and seize it in our fingers, but a dead or quiet fly he
never would touch, At other times dozens of flies and grass-
hoppers have been left in his cage, and waking him by their
noise, he dexterously caught them as they hopped or flew
about, but uniformly disregarded them while they were at
rest. ‘The common Blatta, hard Beetles, and Caterpillar he
refused, even after he had been induced by their moving to
attack them. As we became still more familiar our new friend
was invited to join in our evening amusements, to which he
contributed his. full share by flitting round the room, at times
settling upon our persons and permitting us to handle and
caress him. He announced his being awake by a shrill chirp,

* Read at the first Philosophical Meeting of the Camden Literary and
Scientific Institution, January 26, 1836: and now communicated by the
Author.

Third Series. Vol. 8. No. 47. April 1836, 2E

266 Mr. Sowerby on the Habits of the Long-eared Bat.

which was much more acute than that of the Cricket. Now
was the proper time for feeding him. I before stated that he
only took his food alive: it was also observed that not only
was motion necessary, but that generally some noise on the
part of the fly was required to induce him to accept it; and
this fact was soon discovered by the children, who were en-
tertained by his taking flies from their fingers as he flew by
them, before he was bold enough to settle upon their hands
to devour his victims. ‘They quickly improved upon their
discovery, and by imitating the booming of a bee, induced
the bat, deceived by the sound, to settle upon their faces,
wrapping his wings round their lips and searching for the ex-
pected fly. We observed that if he took a fly while on the
wing, he frequently settled to masticate it; and when he had
been flying about a long time he would rest upon a curtain,
pricking his ears and turning his head in all directions,
when if a fly were made to buzz, or the sound imitated, he
would proceed directly to the spot, even on the opposite side
of the room, guided, it should appear, entirely by the ear.
Sometimes he took his victim in his mouth, even though it
was not flying; at other times he inclosed it in his wings, with
which he formed a kind of bag-net; this was his general plan
when in his cage, or when the fly was held in our fingers or
between our lips.

From these observations I should conclude that many of
the movements of the Bat upon the wing are directed by his
exquisite sense of hearing. May not the sensibility of this
organ be naturally greater in those animals whose organs of
vision are too susceptible to bear daylight, when those organs,
from their nature, would necessarily be of most service? such
as the cat, who hunts much by the ear, and the mole, who
feeding in the dark recesses of his subterranean abode is very
sensible of the approach of danger and expert in avoiding it.
In the latter case large external ears are not required, because
sound is well conveyed by solids and along narrow cavities.
In the cases of many bats and of owls the external ears are
remarkably developed. Cats combine a quickness of sight
with acute hearing; they hunt by the ear, but they follow their
prey by the eye. Some bats are said to feed upon fruits; have
they the same delicacy of hearing, feeling, &c. as others ?.

[ 267 ]}

LIV. Observations on the frequent Presence of Lead in En-
glish Chemical Preparations ; on the Cause of that Pre-
sence; and other Remarks relative thereto. By Gustavus
ScHWEITZER*.

THE examination of the purity of chemical preparations,
in which I have been engaged for some time, convinces

me that many of them are impure and contain lead. In se-
veral which I have examined I have found subcarbonate of
magnesia containing lead in the proportion of 2°40 grains
subcarbonate of lead in 1000 grains of subcarbonate of mag-
nesia. Bicarbonate of potash contained a similar proportion ;
bicarbonate of soda, subcarbonate of ammonia, &c. showed
the same impurity. It is clear, when these substances, so
universally used, contain lead, that many other combinations
which are prepared from them must be equally impure. The
cause of this impurity arises greatly from the manner in which
these substances are prepared. Leaden vessels are too often
used for the crystallization and precipitation of them, and how
easily alkaline substances act on lead is too well known to
need comment. But another cause of this impurity, although
the portion present is but very small, is the white glass used
in this country, which must be an object of great consequence
to practical chemists and druggists. I know not whether any
direct experiments have been made to show what influence
alkalies, acids, and salts may have on white glass. I have
therefore endeavoured to ascertain this point by the following
experiments. White glass bottles, such as are used for medi-
cine, were taken and filled, some with distilled water and
others with common water. No lead was imparted to the
water in either case, even after immersion in it for a few
weeks exposed to a common temperature; but when the di-
stilled water was impregnated with carbonic acid gas, after a
few days the fluid gave, with the proper tests, ample proof of
the existence of lead; and when boiled to expel the gas, no
indication of lead was obtained, proving that a bicarbonate of
lead was formed by the action of the carbonic acid gas on the
lass. Acetic acid, nitric acid, muriatic acid also take up
an from white glass. Diluted sulphuric acid, after standing
some time in these glasses, shows no indication of dissolved
lead, but after pouring off the acid and rinsing the bottle
with nitric acid the presence of lead was detected. Neutral
salts showed an equal action when they contained such acids
as produce with oxide of lead insoluble combinations, or com-

* Communicated by the Author.
2E2

268 Mr. Schweitzer on the Cause of the frequent Presence of

binations of very sparing solubility, and produced more or
less a film on the glass, which film was dissolved by nitric
acid;—as the phosphates, oxalates, chromates, sulphates.
Chloride of lead is but slightly soluble in pure water, and
according to my analysis 100 parts of distilled water will dis-
solve 0°74 part of chloride of lead. Solutions of chlorides
will also dissolve chloride of lead, more or less, according to
their strength, but still less than distilled water, because when
to a concentrated solution of chloride of lead in distilled
water a few drops of chloride of calcium of 0°2 strength are
added, the greater part of the chloride of lead will be sepa-
rated, but by chloride of calcium in excess the chloride of lead
will be retaken up. (Bischof, Neues Jahresh. d. Chemie und
Physick.) This 1 found to occur with the chlorides of am-
monium, iron, lithium, magnesium, potassium, sodium, and
zinc, and most likely will be proved to be the case with all
chlorides of a corresponding strength. Therefore chloride of
lead will be imparted to a solution of a chloride when kept
in white glass bottles according to the strength of the solution
of the chloride; the more chloride the solution may contain
the less will be taken up of the chloride of lead. The chlorides
will take up by boiling a considerable quantity of chloride of
lead, a portion of which will crystallize when the fluid is
cooled down.

Caustic alkalies act very powerfully on white glass, and
much oxide of lead will be dissolved. Caustic ammonia acts
very slightly on the glass; subcarbonate of potash, soda, and
ammonia also take up lead, but considerably less than the
caustic alkalies. A strong solution of ‘the subcarbonates will
take up less than a diluted one. Volatile oils show no action
on the glass. ‘These experiments prove that the white glass
bottles commonly used are not fit for chemical and medical
purposes; which fact is worthy of the attention of the Medical
Board. The great addition of oxide of lead in the manufac-
ture of glass to make it more fusible must be avoided. Accord-
ing to the analysis of Faraday, the ordinary flint glass contains
33°28 per cent. of oxide of lead, whereas for all chemical or
medical purposes a glass free from lead should be used.

A piece of lead perfectly clean and bright on the surface
was kept in distilled water in a closed vessel, and after some
time showed a white crystalline coating of subcarbonate of
lead; the fluid was also filled with little crystalline scales.
The fluid turned red litmus-paper blue, and tests indicated
freely the presence of lead in the fluid; but when it ‘was care-
fully filtered through paper which had been freed by weak
nitric acid from its impurity, no indication of lead whatever

Lead in English Chemical Preparations. ‘269

was perceived, showing that the carbonate of lead was merely
dispersed in the water and not dissolved. A similar effect
was shown by oxide of lead treated with pure water, but no
solution of it was perceptible if it was kept with the water,
whether in an open or a closed vessel 3—a fact which is op-
posed to the received opinions*. Well-water and mineral
water corrode lead, forming a coating of oxide of lead on the
metal without taking up a particle of the oxide; but mineral
waters strongly impregnated with carbonic acid gas I found to
‘contain faint traces of lead, when they had been for some time
in contact with it. Mr. Walker according to his analysis found
in the mineral water of Bath, lead originating from the pipes
or pump used for the conveying of the water. (Quarterly
Journal of Science, Literature, and Art, January to March,
1829.) Might not the lead in these instances be dispersed
mechanically in the water? The result of my experiments
induces me to believe so.

Volatile oil dissolves lead freely. Alcoboland gether, when
pure, do not act on that metal. When an alkaline fluid contains
a trace of lead, the best test to apply is the hydrosulphuret of
ammonia, as this reagent will detect s00.000 gt: of crystallized
acetate of lead; but this is almost the limit of its dilution, as
the observation must be made by the light falling upon the
surface of the liquid, which must have a diameter of not much
less than one inch. In a neutral fluid, or in one which is only
slightly acid, the presence of lead may be shown by the appli-
cation of sulphuretied hydrogen gas; but it is advisable to avoid
the use of nitric acid, as by a little surplus of it faint traces of
lead will be easily overlooked. Acetic acid is preferable be-
cause its surplus does not affect the delicacy of the hydrosulphu-
retted gas. Very good tests also are soluble sulphates and chro-
mates, particularly to decide on the nature of the metal, al-
though not to such an extent as the tests before mentioned,
Chromate of potash will indicate traces of lead, when sulphate
of soda ceases to do so. Sulphate of lead will be partly dis-
solved by concentrated nitric acid ; muriatic acid shows traces
of lead; acetic acid only faintly shows them. Chromate of
lead when treated with strong sulphuric acid will be changed
into sulphate of lead, and the decanted acid will contain no
lead. Nitric acid dissolves traces of lead from the chromate;
muriatic acid changes the chromate of lead into chloride of
lead and the chromic acid into oxide of chrome by develop-
ing chlorine, particularly by the application of heat. Acetic

* Handbuch der theoretischen Chemie von Leopold Gmelin, 1 Band, 2 Abth.

P. 1073. [See on this subject Capt. Yorke’s paper in Lond. and Edinb.
bil. Mag., vol. v. p. 81.—Kprr.]

270 Mr. Tovey’s further Researches in the

acid acted on chromate of lead and took up some lead, parti-
cularly when the acid was for several days in contact with it:
according to Mans, (Poggendorff’s Annalen, band ix. p. 127.)
it is not soluble in acetic acid.
Royal German Spa, Brighton, Gustavus SCHWEITZER.
November 29, 1835.

LV. Further Researches in the Undulatory Theory of Light.
By Joun Tovey, Esq.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

oy that my paper on the relation between the
length and velocity of a wave of light, inserted in your
Number for January last, has received, in your Number for
February, a favourable notice from your eminently scientific
correspondent Professor Powell, I venture to send you a con-
tinuation of my researches.

My object now is to transform the general equations (3.)
of that paper, into others adapted to any case of undulation
in which the directions of the coordinates can be so taken
that the displacements §, , , may be regarded as functions of
z and ¢.

On the condition just stated, we have, by Taylor’s formula,

aye Me Ax Be Az® diz Axt
Pi eet gas Bh) Gee hiae Vida ene
ek) d*y Ax* O° 4 ee. ig ee
BS ae date oo. Get hes cl aetna
dé GO DOG? Ot a A ee cake

Tek Tiga tt ag ga ges tng rel ara

+ &e.

+ &c.

+ &c.

Now, suppose the arrangement of the molecules in the state
of equilibrium to be such that for every molecule on one side
of m, within the sphere of its influence, there is another at
an equal distance on the opposite side; then, if we substitute
these expressions for A£, Ay, AZ, in the first of the equa-
tions (3.), the sums =. ¢(7) Az, 2.¢(r) Aa’, TE. (r) A 2,
Sais) Avy Z.v(nAyAx, z.v(r)AyAdc*,
=. (r) AzAa’, E.(r) Az Azt, &c., in which the degrees
of the products of the variations are odd, will vanish ; be-
Cause, whatever be the signs of Aw, Ay, Az for any molecule,
these signs will all be changed for the corresponding mole-

Undulatory Theory of Light. 271

cule on the opposite side of m; consequently the signs of the
odd products of the variations will be changed, while the ab-
solute values of the variations and of their products remain
the same for both molecules. This supposition respecting the
arrangement of the molecules is due to M. Cauchy, and ap-
pears very probable; because it seems impossible to conceive
how the equilibrium could subsist unless it were true. It is
also probable that the sphere of the influence of each mole-
cule comprehends a great number of other molecules; and
accordingly we shall assume this as an hypothesis. Now, as
we cannot suppose the molecules, in their state of equilibrium,
to be more crowded in one part of the sphere than another, it
follows that the terms of the other sums =. (r) Ay A 2’,
V(r) AyAxr, =.y (7) AZAz, =. (7) Az Az’, &c., in
which there are odd powers of the variations, will be about
half of them positive and half negative, and will nearly destroy
each other, and consequently these sums will nearly vanish.
Neglecting them as well as the former, the first of the equa-
tions (3.) becomes, by the substitution,

ae Age ae
Tea me{ (He) +9008). (Fae +58 Ae 4 ke) |

The second and third of the equations (3.) are of the same
form as the first; consequently, if we transform them in the
same manner, and, for the sake of abridgement, put

> =. (¢ (7) + b(r) Az*) Ax? = 3?

m™ f " :

aage (or) + ¥ (7) Aw’) Act =
&e. &e.

F=-(¢ (r) + W(r) Ay’) Aa? = s?

(1.)
mE. (O(r) +H (r) Ay?) Artes 5)

2.3.4
&e. &ce.
m
a = .(¢ (7) + P(r) Az’) Aa? = a
bee

or Z.(o(r) + ¥(r7) Ar) Aat= af"

&ec. &e.
we shall have

272 Mr. Hopkins’s Abstract of his Memoir on PhysicalG eology.

d?é ACTS aE is d'é ,
de satin gee “agit &e ’
d?y d?y d‘

ae Hs ae + Phy + Be. (2.)
Se RE 94 hat tha

de el dia? + Sy dx + &e.

These equations show that the displacements in the three
rectangular’ directions are, to the extent to which we have
carried the approximation, independent of each other.

We have supposed the masses of the molecules to be all
equal; but if the medium be composed of two fluids uniformly
mixed, and if the masses of the molecules of one fluid be all
equal to m, and of the other all equal to m', the equations
(2.), which we have just obtained, will still be of the same
form ; because each of the sums = may then be divided into
two parts, one of which parts, multiplied by m, will embrace
the molecules of one of the fluids, while the other part mul-
‘ tiplied by m/, will comprehend the molecules of the other
fluid ; and the molecules of each fluid may be conceived to be
arranged in the manner which we have supposed. In this way
the equations may be extended to the case of any compound
medium in which the elementary media are uniformly mingled.

In another communication I propose to deduce the inte-:.
grals of the equations (2.), and point out the extent of their
application. I am, Gentlemen, yours, &c.

Evesham, Feb. 9, 1836. Joun Tovey.

P.S. There are three typographical errors in my last paper.
At page 9, line 12, for z read Az; page 10, line 3, for dz
12

read A 24; and line 22, same page, for s” read ee

LVI. An Abstract of a Memoir on Physical Geology ; with
a further Exposition of certain Points connected with the
Subject. By W. Horxins, Esq., M.A., F.G.S., of St. Peter’s
College, Cambridge.

[Continued from p. 236.]

LE HAVING now reduced the determination of the hori-

zontal directions of the fissures produced in the ele-
vated mass to that of the fissure which would be produced
in a plane lamina every point of which is subjected to known
tensions, we may proceed with this latter problem. Our first.
object is to determine the direction in which the tensions have

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 273

the greatest tendency to cause a fissure to begin at any proposed
point. ‘To give all requisite generality to the investigation,
let us suppose there to be any number of these tensions, and
let F, f,,,f:, &c. denote their respective intensities at any pro-
posed point, 8,, 8, &c. the angles which their directions
make with that of F;

b= A, hog = = es

ze cos2B = p, cos 26, + p.cos2 6, +, &c.
v the angle which the required direction makes with that of
F; we shall have for the determination of ¥,

1+ pcos 26
' =psin 2 B

This equation will determine the direction in which the ten-
sions have the greatest tendency to cause a fissure to begin at
any assigned point, but when its formation has begun, it is ob-
vious that the state of tension in its immediate vicinity must
be altered, and that the tensions thus modified may not have
a tendency to continue the fissure in the same direction as that
in which it was the tendency of the original tensions to make
it begin. I have shown, however, that with our hypothesis
as to the mode of action of the elevatory force (see p. 234) the
above equation will be very approximately applicable to the
action of these modified as well as to that of the original ten-
sions.

The actual direction in which the fissure will be formed
will not in all cases depend solely upon this tendency of the
tensions, but partly also on the constitution of the elevated
mass. If, however, its cohesive power be perfectly uniform,
it is manifest that this direction will be determined by the ten-
sions alone, or will coincide with that given by the above
equation. It will appear also that this is equally true in cer-
tain other cases; when it is not so, the effect of any peculiar
constitution of the elevated mass must be investigated. I shall
now proceed with these points.

Let us still confine our attention to a simple lamina of uni-
form thickness. Its cohesive power at any proposed point
may be estimated in exactly the same manner as the intensity
of the tension at that point. Let the point of the lamina be
designated by P, and draw through it, in any direction in the
plane of the lamina, a straight line whose length is unity.
Then conceive two equal and opposite forces (f/f) acting

cot?» + cot P—1 = 0.*

* See Memoir, p. 18. + Memoir, pp. 20, 21. t Memoir, p. 13.
Third Series. Vol. 8. No. 47. April 1836. 2F

274 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

uniformly along this line perpendicular to it, and in the plane
of the lamina, on the contiguous particles situated respec-
tively on opposite sides of the line, thus tending to form
a fissure along it. The cohesive power opposes this tendency,
and if it be uniform along the line just mentioned it will be
measured by that value of f which is just sufficient to over-
come it. Ifthe cohesive power along this line be variable, f
will manifestly not be a measure of it with reference to the
single point P. In such case we must conceive the cohesive
power to be equal (for the unit of length) at every point of
the line to that at P, and then that value of (which we may
designate by 11) which would, under such circumstances, just
overcome the cohesive power, may be taken as a measure of
it at the point P, when estimated in the direction perpendicu-
lar to the above line through that point.

In the first place let us suppose the value of II the same for
every direction of this line; then is it manifest that the direc-
tion in which a fissure may be formed immediately at the
point P cannot be determined in any degree by the cohesive
power, since its value is the same for every direction through
P. The same conclusion will clearly apply to every point
where the value of II is independent of angular direction, and
equally so whether 17 be the same or different for different
points, 7.e. whether the cohesive power be uniform or vari-
able, so long as its variation depends solely on the position of .
the point P; or, in mathematical Janguage, the above con-
clusion will hold whenever I is a function only of the co-
ordinates of P. In such case then, the fissure will be formed
through P in that direction in which the tensions there have
the greatest tendency to form it, and our equation will be as
strictly applicable for the determination of this direction as if
the lamina were perfectly homogeneous. We shall be able
shortly to extend still further the conditions under which this
equation will be similarly applicable.

It is easy to extend the above reasoning from a lamina to
the general elevated mass.

If, however, the value of I be different for different angu-
lar positions of our line of a unit of length through P, (as,
for instance, when a laminated or jointed structure prevails
in the mass, or any accidental line of less resistance passes
through the proposed point,) it is manifest that the direction
of the fissure there will depend on the tensions and this vari-
able value of IJ conjointly, and the equation above given will
no longer suffice generally for its determination. ‘The case of
Jaminated or jointed masses I professedly exclude from these
investigations, since their lines of dislocation will’ necessarily

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 275

be principally determined by their peculiar structure, and
will therefore be in great measure independent of the causes
whose effects I am investigating. The case however of the
existence of partial and irregular lines of less resistance, re-
garded as modifying, and not as principal causes, comes within
the sphere of our investigations. We may now proceed to
this point.

. Recurring again to the simple case of a lamina, it is easily
shown* that if a fissure in its continuous propagation through
consecutive points meet a line of less resistance, it will be
propagated across it without change of direction, or along it,
according as a certain condition is or is not satisfied, this con-
dition depending on the angle at which the fissure meets the
line of less resistance, and the cohesive power along that line
estimated in a direction perpendicular to it.. If this angle be
a right angle the condition is necessarily satisfied, as it must
be also if the angle do not deviate much from a right angle,
unless the cohesive power just mentioned be extremely small,
so that in such cases the line of less resistance will have no
effect on the direction of the fissure. If the angle just men-
tioned deviate too much from a right angle, the fissure will be
propagated along the line of less resistance; but I have
shownf that when this ceases to be the case it will almost im-
mediately resume the direction determined by our equation,
so that if these lines of less resistance exist only partially and
irregularly, and be of limited extent, they will only produce
partial deviations in the direction of the fissure, without very
materially affecting its general bearing. This reasoning again
is easily extended to the general mass.

We shall now be able to arrive (as intimated above) at
another and important condition respecting the constitution
of the elevated mass, with which our equation will be strictly
applicable to determine the direction of a fissure. Ifa single
tension act at a point of a lamina, it is easily shown (and in
fact is in itself sufficiently obvious,) that the resuiting fissure
will be perpendicular to the direction of the tension, the co-
hesive power being such as above shown (p. 274) to be consis-
tent with the strict application of our equation. In like man-
ner it may be easily conceived, that since all the tensions act
in the planes of their respective laminae, whatever their hori-
zontal directions may be, the resulting fissure, whatever may
be its horizontal direction, must necessarily (independently
of perturbing causes,) lie in a plane perpendicular to each
Jamina at the points where it intersects it. Hence, then, it

* Memoir, p. 24. + Memoir, p. 23. t Memoir, p. 14.

2¥F¢2

276 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

follows that however small the cohesion may be between two
successive lamin or strata, this will produce no effect on the
position of the fissure. In such case then its horizontal di-
rection will still be accurately determined by our equation.
‘This is important, because in a stratified mass the cohesion
between different beds must probably be often much less than
that between the constituent particles of each bed. The same
conclusion will hold with respect to any accidental planes of
less resistance which do not deviate too much from horizon-
tality ; but if they be vertical, or nearly so, they will produce

‘the accidental and partial deviations which have already been
noticed.

In forming a judgement of the probable extent of these
planes of less resistance, we must be careful not to be too
much influenced by the impressions produced by the exami-
nation of a disturbed district, since we are now speaking of
the existence of these planes in the undisturbed mass. I would
also observe, that we are only concerned with this kind of
discontinuity in the cohesive power, so far as it depends on
local and irregular, and not on general causes, since, as already
stated, I exclude those cases in which any regularly jointed or
laminated structure may be supposed to have existed in the
mass previously to its elevation. Now as far as the planes we
are speaking of might be caused by accidental circumstances
in the constitution or deposition of the mass, it would seem
necessary to suppose them irregular in position and partial in
extent; in which case, as we have seen, partial deviations
only would be produced by them in the vertical or horizontal
directions of the fissure.

It appears then from what has preceded, that the equation
above given will accurately determine the direction of a fissure
at any proposed point, produced by tensions such as we have
supposed, not only in a homogeneous mass, but also in a mass
in which there may be any number of planes of less resist-
ance, provided they do not deviate too much from horizon-
tality, and notwithstanding any variation in the cohesive power
of the mass depending on the difference of position of one
point and another. From the interpretation of the equation,
it appears that the fissure (or rather its intersection with a
horizontal plane) will in general be rectilinear only in the

, &c. are the same

fi, fa
F

particular case in which the ratios : r?

for every point through which it passes, supposing the direc-
tions of the tensions at one point respectively parallel to those
at another. There is, however, one important exception, viz.

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 277

the case in which there are two tensions only, and these ten-
sions at right angles to each other. The direction of the fis-
sures will then be always perpendicular to that of the greater
tension. If therefore the directions of this tension at different
points be parallel to each other, the fissure will be rectilinear,
whatever be the ratio of the two tensions. The case of a
single tension is a particular case of the above, when the

smaller tension vanishes. If there be two tensions making an

acute angle with each other, the direction of the fissure will
be within the exterior or obtuse angle between the directions

. . . 5 .
of the tensions; and if one tension be considerably greater

than the other, or if the angle between their directions do not
deviate materially from a right angle, the fissure will lie much
nearer to the direction of the smaller tension* than to that of
the greater.

III. Having thus explained how a single fissure may be
formed, and its direction determined, let us consider the for-
mation of a number of similar fissures all following the same
law, and not remote from each other, thus forming a system
of fissures. In the greater number of cases in which such sy-
stems have been recognised the lines of dislocation have been
approximately rectilinear and parallel. It will suffice, there-
fore, to take this case, which will be somewhat the most simple
to explain.

In the first place I have considered in my memoir, how far
it would be possible that the fissures of a system should be
formed consecutively. For this purpose I have examined the
modification which would be produced in the tension of the
mass by the existence of a rectilinear fissure extending for any
assigned distance, assuming, for the greater simplicity, the
mass to be acted on by one system of tensions perpendicular
to the fissure ; and it appears that if we draw a line perpendi-
cular to the fissure and meeting it at a point P, not too near
its extremities, the tension at any proposed point of this line
and in its direction (or perpendicular to the fissure) will be
less than that which will be caused by the existence of the
fissure, in a direction parallel to itself, provided the distance
of the proposed point from the fissure be less than the radius
of curvature at P of the curve formed by the intersection of
the vertical side of the fissure with a horizontal planet. Now
it has been before stated that when there are two tensions at
any point in directions perpendicular to each other, if they
produce a fissure it must be perpendicular to the greater of

* Considerably nearer to it than the resultant of two forces respectively

equal in intensity to the two tensions, and in the same directions.
+ Memoir, p. 33.

278 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

these tensions, and therefore, in the present case, perpendi-
cular to the former fissure. Consequently, since the radius
of curvature above mentioned will, if the fissure be of con-
siderable length, be very large at every point, it will be im-
possible for a second fissure to be formed parallel to the first
and not very remote from it, by the general tensions to which
the mass is supposed to be subjected *.

We may conceive, however, any number of parallel fissures
in the case we are considering to be formed simultaneously.

Acotctgtt aes Bute ae

a ey
Thus suppose two parallel fissures, AP, A'P’, produced by
tensions acting perpendicularly to their directions, to begin
simultaneously at A and A’, and also to arrive at P, P’ at the
same instant, P P! being perpendicular to A P and A’ P".
There will manifestly be no reason why they should not in
such case be continued simultaneously from P, P’, just as they
began at the same instant at A and A’. If, however, the re-
laxation produced by the opening of A P be communicated
through the distance P P! instantaneouslyt, it is clear that as
soon as A P should have advanced in its progressive forma-
tion by the smallest quantity further than the other fissure,
the formation of this latter would be instantly arrested. Un-
der such circumstances, then, the possibility of the simulta-
neous formation of two or more fissures would be rather a
mathematical than a physical possibility. The fact is, how-
ever, that the relaxation produced by the one fissure is not
communicated instantaneously to the distance of the other.
Time will be necessary for this purpose, and this removes the
difficulty of conceiving this mode of formation, since it is no
longer necessary that the velocities of propagation of the two
fissures should be mathematically equal. For, suppose one
fissure to have reached P when the other has reached Q’,

* If there were another system of tensions perpendicular to the first,
this conclusion weuld be true for still greater distances from the existing
fissure. We may remark that these two cases of tensions would seem to be
the only ones in which systems of rectilinear parallel fissures near each other
could in any way be produced. See Memoir, p. 36.

+ This would be the case if the mass were absolutely inextensible.

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 279

then it is easily seen that if the velocity of propagation of the
first fissure should be such as to continue it from Q to P, in
less time than the relaxation of the tension would be commu-
nicated from Q to Q’, (Q Q' being parallel to P P’,) the con-
tinued formation of A! Q’ would not be arrested. Now I have
shown* that the velocity of propagation will be extremely
great, so that the distance Q! P’ may be large, and all physi-
cal impossibility is therefore entirely removed. Let us sup-
pose, for instance, a system of parallel fissures to begin simul-
taneously along the lower surface of the elevated mass, and
to be propagated upwards +. If the mass be nearly homoge-
neous, the velocity of propagation will be nearly infinite; and
if the fissures be not too near together, it is very possible that
the time requisite for the relaxation of the tension to be com-
municated from one fissure to the distance of the next, may
be greater than that which is necessary to propagate the fis-
sures to the upper surface of the mass. In this case it is
manifest that every fissure will necessarily be continued to
that surface. It seems most probable, however, that in actual
cases, similar to that just stated, a part only of the fissures
commencing below would reach the higher portion of the
mass. If its thickness should be very great, the fissures
reaching the surface would probably be at a proportionally
greater distance from each other.

In this manner, then, the formation of systems of parallel
fissures presents no difficulty. Adopting this view of the sub-
ject, we are immediately led to the conclusion, that the whole
of any disturbed district, characterized by a continuous system
of parallel dislocations, must have been elevated simultaneously.
It is not, however, here meant to be asserted that the whole
elevation must have taken place at once, but that that move-
ment which determined the positions of the principal and cha-
racteristic dislocations by causing the commencement of their
formation, must have been a great movement, and must have
extended at least as far as such dislocations may be observed
to follow continuously the same law. Subsequent efforts of
the elevatory forces might take place in any number, but it is
evident that they would have but little effect in producing new
fissures parallel to the former, (since the mass would generally
yield along the old ones,) though they may be very instru-

* Memoir, p. 22.

+ | have shown (Memoir, p. 43) that fissures must generally commence
in the lower portion of the mass; and we may remark, that according to
our hypothesis respecting the rapid increase of intensity of the elevating
force, from the instant the elevation commences, the formation of the fis.
sures must begin almost accurately at the same instant,

280 Mr. Hopkins’s Abstract ofhis Memoir on Physical Geology.

mental in extending those existing previously. Partial eleva-
tions, or subsidences, may be easily conceived to be thus pro-
duced; but whatever alteration may take place in this man-
ner, in the general conformation of the district, must be un-
der the guidance, as it were, of the fissures previously ex-
isting.

Nothing perhaps will tend’'more to corroborate the views
I have been explaining on this important point of the forma-
tion of systems of fissures, than the attempts we may make
to account for it otherwise, assuming always that the phe-
nomena are due to the action of mechanical causes extraneous
to the mass itself, and independent of that kind of internal
molecular action to which the existence of joints, or of a la-
minated structure, may possibly be owing. In the first place,
I have shown that two parallel fissures not remote from each
other could not be formed consecutively by a repetition of
the elevatory action extending to the whole elevated mass;
this consecutive formation, if it should take place at all, must
therefore be owing to consecutive partial efforts of the eleva-
tory force at different points of the mass. But I have shown*
that, if the elevatory force be confined to a portion of the
mass of comparatively small superficial extent, fissures must
either be formed diverging from it in all directions, such as
have been recognised in Mount Etna, and in the groups of
the Cantal and Mont Dor, or concentric about the vertex, so
that it is mechanically impossible that systems of parallel fis-
sures could be thus produced. In fact, I can in no way con-
ceive this successive formation of parallel fissures, without
hypotheses respecting the mode of action of the elevatory
force which are infinitely too arbitrary to be admitted for an
instant.

After one system of fissures is formed, there is no difficulty
whatever in conceiving the formation of a second system per-
pendicular to the former. The existence of two rectilinear
parallel fissures must evidently destroy all tension in the por-
tion of the mass between them, but will have no effect on the
extension, or therefore on the tension which may exist in a
direction parallel to the fissures, the only one in fact in which
any tension can be impressed on a part of the mass so situ-
ated. Consequently whatever tendency there may be to form
a second system of fissures, it must necessarily be in a direc-
tion perpendicular to that already existing. This second
system might be formed by any forces, however partial or
irregular their action, (always assuming ft not absolutely zm-

* Memoir, p. 47.

“Mr. John T. Graves on the Logarithms of Unity. 281

pulsive,) since the only direction in which the mass ‘could ad-
mit of any tension being impressed upon it would be, as just
stated, that parallel to the first system. It seems to be me-
chanically impossible that any second system of parallel fissures
could be thus formed except in the direction here stated.

[To be continued.]

LVII. On the lately proposed Logarithms of Unity, in Reply
to Professor De Morgan. By Joun T. Graves, of the Inner
Temple, Esq., M.A.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

| the Philosophical Transactions for 1829, and in the abs-

tract of a memoir printed in the Fourth Report of the
British Association, it is proposed to modify the ordinary
formule for the logarithms of unity and of numbers in general
by certain rather startling extensions. These innovations
Prof. De Morgan is not disposed to admit, as appears from sec-
tions (158.) and (245.) of his able and useful Treatise on the
Calculus of Functions, recently published in the Encyclopedia
Metropolitana. His principal difficulty seems to be founded

Qin
on his dissent from the proposition that e 247-vW—-1 = i,

and accordingly be challenges the supporters of the new
theory to the proof of that equation. Now in one sense I do
Qin
not either assert or admit its accuracy; for e2t™—W—1 has
many values, while 1 has only one. I am bound, however,
Qin
to show that 1 is among the values of e2in— V¥—=1, To
show this would be to prove, that, according to my under-
standing of the term, tho is a Neperian* logarithm
of 1. Icall} an e-log. of —1/e as wellas of +c. If

I am told that logarithm ought to be so defined that x ought
to be called an a-log. or a logarithm to base a only of the®

* I have been accustomed to write “ Neperian” instead of “ Napierian,”
because the inventor of logarithms, in the title of his original work on the
subject, signs his name in Latin, “ Neperus”’ ; because the Scottish mode
of spelling the name was unfixed in his time, and because foreigners have
generally adopted the Latin orthography.

Third Series. Vol. 8. No. 47. April 1836. 2G

282 Mr. Graves’s Repiy to Prof. De Morgan’s Remarks

arithmetical value of a’, I must say that I should not approve
such a restriction. It would, if the proposed theorems be cor-
rect, arbitrarily exclude from the xame of logarithms orders of
functions which enjoy the same fundamental and characteristic
properties as those that are favoured with that name. It would
also in some cases be difficult of application. The expression
= a =
(m—/ —1%)? has two values. If we adopt the restricted
definition, of which of those values shall we be allowed to call
1 a logarithm with reference to the base m— 7 —1n? On
the other hand, there are cases where a” has an infinite num-
ber of real and positive values. But I proceed to prove that
Qin
1 is among the values of e 2¢m— V —1 from postulates which
I believe will be conceded by Professor De Morgan.
For all values of x, real or imaginary, by cos z, I denote

a x x
1 eh een Asse a ee
and by sin x I denote
wv a 2 a’
TRILL SST ML SAG LLSAse Cee
I assume that
j 2 qa?
Rebige Tongegnit ages? Pe:
Athi y* y
sles fig Wye tout
(vty) , (waty)? , (e@+y)* 3
it 1 Tantdes T 7.2.3 vip (3.)
that the complete and correct equation for e” is
aneee x x a
Ante (14 ig. Ce aes (-

and that, if w denote in succession O and all integers positive
* and negative, the values of 1° are properly represented by the
formula

cos (2wam)+* 7 —1 sin(2wez). (5.)

* I have found that upon the whole it tends to superior clearness of

notation to place ./—1 foremost.where it occurs as a factor.

on the lately proposed Logarithms of Unity. 283
From these premises it follows irresistibly that

ghee {1+ eres + Be Fr wb

2 Cag
cist jal alae Opn (6.)
but by (3.) this product is equal to

(Y—12wr+1) | (W—12wr+l)?
esim@L, yal Sips tga 1.2

x

i

(7 —12w2+1)
1.2.3

The development (7.) therefore is complete and correct,
having as many values, and only as many, as e”.

é Zea, (7.)

3 End a 21 ’
To apply this result, on substituting ee ae for x in
Qix 1
(7.), we find that the values of e 2?7—~—1 are represented
by the formula

ap (Gv) Lvichaia

2imr—V/—1
2war—V/—1\? (7 —1 2i7)
es eer 1.2
2wr—V/—1\3 (VW —1 iz)
ty ™— Vai) 1.2.3 (8)

Now, among the values of (8.), which are found by giving
to win that formula all its values in succession, there is one

Qin
value (which I denote by e; 2**—“—1) that will correspond
to the case of w = i, in which case the development (8.) re-
duces itself to

(f—12in) (W=—19ir? W—12in)3
ie die en ee gag Pc} ON) LE

= cos(2im)+ /f—I1sin(2inz) = 1. Q.E.D.

eee

It may be remarked that, tested by formula (7.), the ex-

pression ¢ /—12i% wil] be found to have an infinite number
2G2

284 Mr. Graves’s Reply to Prof. De Morgan’s Remarks

of real values, which are successively equal to 1, and to the

. . —din*®_. . .
ascending integral powers of e, 4’ o° with their reciprocals.

The expression e,~4'™’ is equivalent to cos (/ —1 477°)

+7 —1 sin(/—1 422°). In these investigations there is
often much convenience in thus putting imaginary quantities
after sin and cos, and the want of familiarity with this practice:
has, perhaps, been an obstacle to the full comprehension of
the new theory.

There is another objection started by Professor De Morgan
but not pursued. He says that after supposing a = /4,
where f§ = cos 6 + 7 —1 sin 6, I find a = f(xf-a), but
that I should have obtained precisely the same expression, if
I had assumed 6 = e°*, c being any quantity whatever. By

e°*, I here understand the Professor to mean ‘hat particular

cé site c 6 (c 6)* (c4)°
value of e-~ which is equal to 1+ — + eo ay 1.2.3

1
and which I should denote by ey *. On this understanding

I fully agree with his statement, but not with the inference
which I suppose him to draw from it. I suppose him tacitly
to infer, without minute examination, that when /@ = cos 6

+ eee,

+ s/—1 siné, or &”“—14 the expression f(2f-!a) cannot
have so general a meaning as it would have if the meaning of
f$ were generalized in the mode he mentions. ‘This is an in-
ference which, if the functional definition of a* adopted by
me were admitted to be proper, would at most only charge
my solution with not being sufficiently general. I acknow-
ledge, indeed, that the impropriety of that definition would
be evinced, if it fairly led to a meaning of a? which subverted
any established exponential theorems more fundamental than
those which that definition embodies, or if by the inconvenient
generality of the values it would comprise, the expediency of
a further limiting equation of condition were pointed out.
The supposed inference, however, as above stated, is not cor-
rect, for it happens that even if /@ were assumed equal to

2 3
oh Leh

1 1.2 1.2.3
be unaffected by any variation of c, since it would indicate
operations which would eliminate ¢ from the result. That re-
sult would in consequence be identical with mine, and if ex-
amined with a little attention, would be perceived entirely to

1+

+..., the expression f(x f~'a) would

on the lately proposed Logarithms of Unity. 285

coincide with what is ordinaily understood by a” in all cases
where the meaning of a®. has been fixed by usage, and to
confer a reasonable analogical meaning on a* where usage has
been silent. The definition of a* which I adopt is this: a*
denotes in succession every function ¢ x of x, which, inde-
pendently of x and y, fulfils the following conditions:
or. oy = o(rt+y) (9.)
aca (10.)

This definition is, perhaps, the simplest that could be pro-
posed, the most extensively applicable and the most accordant
of any with other less fundamental properties of a” which have
been observed to hold good within certain limits.

The abstract contained in the Fourth Report of the British
Association does not contain the reasoning by which I find
JF (x f-'a) to be the general solution for a*, f§ being equal to
cos 6 +4/—1 sin 6. My reasoning is as follows:

I first proceed to show that if fx and fx denote two func-
tions of x, each of which fulfils condition (9.), we shall have
Jf 2 = f(x), c being some constant.

Let f' 2 = fa, yx being some unknown function of «,
the form of which is sought: then by the assumed property
of f’, we shall have fpa. fly = fv (x+y); but by the
same property of f,; we have fla. fly =f(ba+ vy).
Hence fy (x# +y) =f(va+ vy).

Now, if ¥ (x + y) differ from Pa + Wy, let 64+ ) (7+ y)
= x+y; then we shall have f{6+¥(x+y)} =f(ve
+vy) =f (c+y); but by the property of f f {6+ (x+y)
any + y); hence fo. fp (e+ y) =f (x + y); hence

il.

Hence the general equation to find Wx is

b+0(r7+y)=vetby, (11.)

§ being some quantity such that f9 = 1.
Let Pr—b=We (12.)

By this substitution we obtain from (11.)
Vety=Vordy (13.)

I consider equation (13.) the purely algebraic part of the best
definition that can be given of what is meant by multiplication
in its extended sense, since that definition is based on the
most characteristic formal property of multiplication in arith-
metic, the science suggestive of symbolic rules, In my view
of algebra, if we presuppose arithmetic in general, and alge-
braic addition, we may at once, on having obtained equation

286 Mr. Graves’s Reply to Prof. De Morgan’s Remarks

(13.), assume v2 = ca, ¢ being some algebraic multiplier,
since it is impossible to arrive at any simpler proof than the
mere form of the proposition.

For those to whom this assumption may not seem satisfac-
tory, we may make the proof that f 2 = c¢ w rest upon dif-
ferent data. Whatever be the form of & and value of 4,
Wie ty +h)—V(e+y)

h
whether / be regarded as the increment of 2 or y. We have
therefore in general

dV (x+y) _ dv (r+y)
PAS GT dy (14)
or, in this particular case, performing the respective partial

differentiations on the equivalent expression in (13.), we ob-
tain

the expression remains unaltered,

d(Vatvy) dvr _dWartVy) dwy
ani Pans or = ee eet (15.)
dVa dy

a? it must be independent

but since is equal to

da

daz
be equal to some quantity fed. We assume that the ge-
neral form of fcdwz is ¢ + ¢.x, but 0 is the only value of cin
the equation P2 = ¢ + cz, which will be found to satisfy
equation (13.). Hence Pa = cz.

Having satisfied ourselves in whatever way, that Va = cx
is the general solution of (13.), we have, by (12.), Ya = 6+ex,
Hence fbx or fx = f(§t+ex); but f(i+cx) = fb. f(c x)
=1.f(er) =f(cr). Hence fr =f (cz).

= ¢, then ‘x must

of x, and therefore constant*. Let

Q. E. D.

Hence, if any function fx could be found to satisfy (9.),

Ff (cx), ¢ being wholly arbitrary, would be the general solution
of (9.). Equation (10.), which defines the base of the system,
limits the otherwise arbitrary c to such values that fc may be
equal to 1. Hence a* = f(cx), ¢ assuming in succession all
the values of f—1a, and none other.

The next step in the investigation is to find some function
(no matter what) that fulfils condition (9.), and to determine
the general form of its inverse. Such a function I find in
cos 6 + s/f —] sin 6.

* By similar considerations we might find at once from equation (9.),

P : é dQu
without having recourse to Taylor's theorem, that oa = cOxn,

on the lately proposed Logarithms of Unity. 287

I have perused with interest Professor De Morgan’s ob-
servations on the impossibility of ever proving that we have
arrived at the most general solution of a functional equation.
It seems to me, however, that our only limit to the meaning
of the general symbols employed in the solution of such equa~
tions is the necessity of their compliance with certain formal
conditions, which must by tacit or express convention be
considered elementary and definitional. Now, I think, we
may sometimes show that given functional equations can be
solved by the solution of certain others expressing such ele-
mentary conditions, and by such solution only. When we
can show this, we are at liberty, in my opinion, to substitute
the symbols which the latter equations define, and to pro-
nounce ourselves in possession of the most general solution.
This subject deserves further consideration.

There is an error in the abstract of my last memoir. I
there appear in substance to define cosine and sine to mean
respectively such functions ¢ and as simultaneously fulfil
thefollowing conditions :

guoy —vabvy = o(e@+y) (16.)
oubyt+veoy=vurty) (17)
(¢2P + (var)? = 1 (18.)

These conditions do not constitute a sufficiently limited de-
finition to coincide with the ordinary acceptation of cosine and
sine. The general solution of (16.) and (17.) gives ¢a

j ays if pate »
a Sex) cake ze) and va = fies) Le 2), where S§
means, as before, cos§ + / —1 sin 4, cos and sin @ being
defined by equations (1.) and (2.).. The third condition (18.)
only requires that c’ should be equal to —<, and so only
limits $v to cos (ca) and Y2 to sin(cx). If instead of the
third condition we were to substitute the following, viz.

dy:

1 by ele 0) ote 5
, we should have a good definition coinciding with
dua Oo

(1.) and (2.).

I am anxious to embrace the present opportunity of cor-
recting a former involuntary misrepresentation with respect
toProfessor Ohm. I find that his logarithmic formule are
not only coincident in principle with mine, but coextensive in
their applicability to imaginary as well as real quantities.

On some future occasion, Gentlemen, I shall be happy,
with your permission, to communicate my investigations re-
lating to the limits of the possibility of finding a base , such

or =

‘288 Prof. Challis on the Phenomena of

that a particular specified value (2;*) of #* may be equal toc, a
and c being given. My results are shortly stated in the Fourth
Report of the British Association, p. 528. The question
bears closely on the subject of the solution of equations in-
volving surds and their “ chance” of representable roots, a
subject which was treated in an interesting and logical man-
ner by Mr. W.G. Horner in a letter to be found, p. 43, of
the January Number of your Magazine for this year. I hope
also that you will be able to find room for a statement of the
restrictions which various ordinary exponential theorems re-
quire, and for a few useful equations and developments.

With sentiments of sincere respect, I have the honour to be,

Gentlemen, yours, &c.,
Inner Temple, Feb. 12, 1836. Joun T. GRAvEs.

LVIII. On the Phenomena of Drops of Oil floating on Water.
By the Rev. Professor Cua.uis.*

AM not aware that the following facts, connected with the

subject of capillary attraction, have been before observed.
A single drop of salad oil was let fall on the surface of water
contained in a glass tumbler, and was seen to spread imme-
diately on the water surface. Another drop let fall shortly
after on a part of the surface not reached by the spreading of
the first, was not observed to spread in the least degree like
the other, but instantly assumed a well-defined circular shape.
The first drop also collapsed by degrees into a circular form ;
and this, it was found by repeating the experiment, was most
likely to happen when the drop was not of very small size.
When two drops fell in very quick succession, both of them
were observed to spread, but that which reached the surface
last, spread in less degree than the other, and sooner assumed
a circular shape. The smaller the size of the spreading drops,
the greater appeared to be their tendency to spread. In one
instance a very small drop was seen to be succeeded by an-
other ata considerable interval, which also spread, but in
much less degree. These phenomena were uniformly pre-
sented in a great number of trials, fresh water being put into
the glass after each. The chief thing to remark is, that without
any visible connexion between the first drop and the succeed-
ing ones, the manner in which the latter are affected on coming
into contact with the water is influenced by the previous con-
tact of the first.

The explanation I propose to give of this fact will be drawn

* Communicated by the Author.

Drops of Oil floating on Water. 289

from the theory of the molecular forces of fluids contained in
my communication to the February Number of this Journal.
It is there supposed that the sphere of action of the attractive
molecular forces of fluids is much greater than that of the re-
pulsive, and that the latter increase so rapidly with any de-
crement of the mutual distances of the molecules, as to be
taken account of without sensible error by considering the
fluid incompressible. On this supposition the angle of actual
contact between a solid and a fluid, or that between two fluids,
is determined by the hydrostatical equilibrium resulting from
the molecular attractions of the two substances, the solid like
the fluid being treated as incompressible. It thence appeared
that this is an exceedingly small angle in cases in which the
bodies in contact are not of very different specific gravities.
Hence in the instance before us, the angle of contact, that is,
the angle which the surface of contact of the oil and water
makes with the upper free surface of the oil, is very small.
Bat since the drop is convex both at its upper and under sur-
faces, this is apparently an angle of considerable magnitude.
In fact the theoretical angle of contact, or that which the
upper surface of the oil makes with an imaginary surface
drawn parallel to its under surface and just beyond the sphere
of the molecular action of the water, would be found by cal-
culation to be of sensible magnitude. Consequently, that the
angle of actual contact may be exceedingly small, the portion
of the upper surface of the oil that lies within the sphere of
the molecular action of the water must undergo a flexure
near the visible periphery of the drop. Now in fulfilling this
condition it seems probable that a very thin film of the oil
spreads over the whole water surface, (as there is no force to
counteract,) and gives rise at the same time to the visible
spreading of the first drop. The film itself being of less
thickness than the radius of the sphere of the molecular action
of the water, will not be perceptible to the senses. Such a cir-
cumstance having happened to the drop that first comes in
contact with the water, will prevent any that succeed from
being similarly affected.

I take this opportunity of adverting to the editorial note
(signed E. W. B.) in the February Number, (p. 172,) on my
communication in that Number, and thanking the author of
it for correcting the erroneous assertion that mercury is inca-
pable of adhering to solids, which was inconsiderately made
of solids in general, when I was more particularly referring
to glass. In accordance with the authorities quoted in the
note, the theory I was explaining would lead to the inference

Third Series. Vol. 8. No. 47. April 1836. 2H

290 Attraction of Aggregation and Chemical Affinity.

that mercury is capable of moistening substances of greater
or not much less specific gravity than itself, by showing that
the angle of actual contact with them may be exceedingly
small.

With respect to the kind of molecular force to which the
mathematical reasoning was intended to apply, I may observe
that in strictness it is applicable only to that which is usually
called the attraction of aggregation, a familiar instance of
which, wholly independent of chemical affinity, is seen in
water adhering to ice. I was unacquainted with Mr. Fara-
day’s observations on this subject referred to in the note, but
having since perused them, I quite agree with him in thinking
that in the contact of two dissimilar substances this force is
modified by chemical affinity, even when no chemical action
takes place between them. There are, however, no means at
present of estimating this effect mathematically. It is pro-
bably greatest in the state bordering on chemical action.
Analysis applied to the case of perfect contact caused by the
attraction of aggregation alone, (which is a simple instance
of the statzcs of molecular forces,) leads to the inference that
the same fluid will rise to the same height in different capil-
lary tubes: and Link’s experiments show, in fact, that water
rose to the same height between glass, copper, and zinc plates ;
sulphuric acid, between glass and copper plates; muriatic
acid, between glass and copper; liquid caustic alkali, between
glass and zinc; liquid ascetic* alkali (sp. gr. 17145), between
glass and zinc. ‘The deviations from the law in the other in-
stances may therefore be owing to chemical affinity, perhaps
also to chemical action. The same causes would affect the
heights of ascent of different fluids in the same tube. But I
am disposed to think that in addition to these causes, the dif-
ference of heights depends on the different natural conditions
of the fluids. For instance, the most volatile fluids, which are
probably those that are most perfectly fluid, appear by the
experiments to rise least. A small degree of viscidity, it will
perhaps be admitted, would tend to increase the height of
ascent, if the condition of perfect contact be maintained. To
separate the effect of chemical affinity from that of the attrac-
tion of aggregation, requires experiments more numerous and
varied than any that have hitherto been made.

Observatory, Cambridge, March 11, 1836.

* [Carbonated ?]

Kii2oa) J

LIX. Remarks on Lieutenant Lecount’s Treatise on Iron
Rails. By Peter Bartow, Esq., F.R.S.*
N amusing but not a very accurate critique of my Reports
to the Directors of the London and Birmingham Railway
Company having been recently published by Lieutenant Le-
count, R.N., which must, I suppose, be considered as the last
expiring groans of the fish-bellied rails, in which critique
many of my formule are made to suffer woful transforma-
tions, allow me in their defence to make a few observations,
and they shall be very few. The author commences his in-
quiry at page 20, and as an earnest of what is to follow, his
very first step is to correct a simple trigonometrical expression
Ihave given, (which is perfectly right as it stands,) and by his
correction to render it ambiguous. With this corrected for-
mula, however, after another forty pages, he contrives to prove
what I have stated at page 19 of my Report, viz. that by taking
a most injudicious form of parallel rail, we may get one inferior
to the fish-bellied rail of the same weight. Now my object has
been to prove, on the other hand, that by choosing a judicious
section we may get one as decidedly superior; and I have
no doubt that thus far both conclusions are just, notwith-
standing the ambiguity of his formula.
As it stands in my Report, the expression is

V(r? + d® —2drcos 2);

and Mr. Lecount, not recollecting that the cosines in the se-
cond quadrant are negative and that “ minus into minus pro-~
duces plus,” has thought it necessary to make the alteration
in question :—any student in trigonometry will judge with what
propriety.

The next 47 pages are employed to prove that all my rules
for the neutral axis are unfounded; which of course they
ought to be, if all Mr. Lecount says about them be correct.
I will not even suspect that he has designedly misrepresented
and misapplied my investigations, but I must say that the re-
sult he conceives he has arrived at, page 107, is very far from
a correct statement. It would seem from what he says, that
I give the ratio of 1 to 9 for all cases. Now, if he had pro-
perly understood what I had done, and if he had wished to
have properly represented it, he would have informed the
reader, that I had given a rule which was general for all bars;
and that as an approximate rule only, sufficiently exact for
all practical purposes, I had stated that taking the neutral axis
in the middle of the head was nearly correct for all the usual
forms of rails, and, as it happens, (the rail in question being

* Communicated by the Author.
AD

292 Mr. Barlow on Lieut. Lecount’s Treatise on Iron Rails.

five inches deep and the head an inch deep,) the ratio in that
particular case is 1 to 9.

The worst, however, is what follows in the subsequent chap-
ters, where he compares my computed, or rather his com-
puted, results with my experiments, and where by a very un-
accountable blunder he mistakes through the other 87 pages
my columns of index readings for deflections, and pays me
and my rules some very awkward compliments because the
two do not agree. Now, I should have wondered very much
if they had, for they might as well be compared with the co-
lumn of sunrisings in any page of an almanac as with the
column of numbers he has mistaken for deflections.

I have explained, (I should havethought sufficiently clearly, )
at p. 36 of my First Report, what these numbers are, and how
the deflections in the adjacent columns are obtained from
them; and must think that Mr. Lecount is the only person who
has yet misunderstood them. I have called them in the head
of the column, to mark the distinction, deflections by index in
some places, and in others index readings; but in ali the
tables the adjacent column is headed deflections for each ton,
and it is this column alone with which comparisons can be
made; and I must repeat that I cannot help thinking that
Mr. Lecount is the only person who has yet fallen into this
singular error. If I had not a better opinion of his integrity,
I should be almost inclined to think it was a designed mistake
to make outa case in favour of the fish-bellied rail, but of this
I most fully acquit him; but then to what am [ to attribute it?
I know but of one other explanation.

As an example or two of the kind here referred to, the
reader will excuse my quoting the following. At page 109
he says, “ Mr. Barlow gives the mean deflection per ton at
015, and the deflection for 74 tons ‘107; whereas in the very
same table, and only three lines above this deduction of +107
deflection for 74 tons, it is shown in the experiment that at
7 tons it was actually °335, or three times greater than that
which is deduced by this mode of proceeding for 74 tons
There is some mistake here evidently.”

Evidently there is, Mr. Lecount, and it is this; you have
mistaken my index readings for deflections: if you will look
again you will find that you could not have found a better
proof of the correctness of my deductions.

Again, page 151, Mr. Lecount says: * Mr. Barlow himself,
p. 103, Second Report, states the deflection by computa-
tion, &c. to be from +051 to ‘055 with 11 tons, although in
the same page, and only three lines above, the experimental
deflection is registered from actual observation 0717. What

Mr. Squire on the Solar Eclipse of May 15th. 293

have we here to do with calculation or hypothesis? We see
the thing before our eyes; the rail does deflect 0717; and why
are we told that it only deflects 055?” Now, I say, the rail
does not deflect 0717: if Mr. Lecount will turn again to page
103, he will find that what he takes for “ deflections by com-
putations, &c. from ‘051 to ‘055,” are the experimental de-
flections ; and that ‘0717, the number “before our eyes”, is only
the index reading.

Mr. L. thus passes through all my pages from 36, First
Report, to 103, Second Report, with a total misapprehension
of my tables. I am sure, therefore, his readers will readily
excuse his having occasionally misunderstood my deductions
from them.

I might, if I had leisure, amuse myself and perhaps the
reader with many other specimens of the author’s ingenuity ;
indeed, I really think he has subjected himself to prosecution
for the torture which he has inflicted on my differential equa-
tions; but I have, perhaps, said enough to show that my rules
are not quite so ill-founded as Mr. Lecount would lead his
readers to believe ; at the same time I will readily admit that
with all the varieties of iron only mean results can be ex-
pected, and “that two bars of the same weight and form will
have different degrees of strength,” &c.; but if I have fitted
them to what iron of a good quality (not the best) ought to
bear, it is all that I profess; and from many experiments made
since my Report was published, I have reason to believe I
have succeeded.

Mr. Lecount concludes his preface by saying: “ It requires
a man of some nerve to face such a leviathan as Professor
Barlow on mathematical points, but it was necessary that some
person should do it, and it appears the lot has fallen on Jonah,
with what advantages others must judge.” Perhaps a little
more attention to what he was reading with a view to criticise
it, would have been better than mere nerve to have contended
with his supposed formidable opponent. As to the advantages,
I must leave that question to be settled between Jonah and his
readers.

LX. On the Solar Eclipse of May \5th, 1836, particularly as
it will be seen at Alnwick, in Northumberland. By 'Tuomas
Squire, Esq.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
F all the anticipated celestial phanomena of the present
year, the large solar eclipse which happens on Sunday,

294 Mr.-Squire on the Solar Eclipse of May 15th.

May 15, p.M., must be considered to rank foremost in a popu- j
lar point of view. This eclipse, it is well known, will be an-
nular in the North of England, and central across Northum-
berland. It also further appears that this central track will
run very nearly over the town of Alnwick, and on looking at
the line of its course, it is clear that this place will be found
the most convenient and proper for observing this eclipse
under its greatest magnitude; with this impression I have
been induced to send you the results of my computations of
the same for that place, with some other trifling matters re-
lating to this subject, which I hope you will find a corner for
in the next Number of the Philosophical Magazine.

Particulars of the large Solar Eclipse of May 15, p.m., 1836 ;
computed for the Latitude and Longitude of Alnwick.*

© eclipsed May 15th, p.m.
comp. for Alnwick.

Beginning.......... 1" 41™58*] ,at 45° 56' 58" west of the ©'s 1.1.
Begs of annulus ....3 5 544 ( )’scentre N. of ©’s = 5!'"1646 ;

: ’ then will the greatest breadth
Middlesg ha. Visi. 3 813349 ofthe annulus be 56/8446,

Visible d@p ....-..3 8 147 and least 46/5154.
End of annulus ....3 10 32:2
End of eclipse...... 4.28 2:1, at 34°54! 46” from the ©’s vertex.

For the basis of these calculations, I have supposed the
geographical latitude of Alnwick to be 55° 25! 22" N. or its
geocentric 55° 14’ 49", and longitude 1° 28’ W. of the Royal
Observatory, Greenwich.

The rare phenomenon of a central eclipse in England, and
the opportunity it offers for scientific inquiry, will no doubt
be an inducement for many gentlemen to visit Alnwick, and
its neighbourhood, for the purpose of making such observa-
tions on the present eclipse as may be conducive to the ex-
tension of our knowledge in astronomy and _ philosophy.
Should the atmosphere be favourable the observer must not
only be careful to observe the beginning and end with the
greatest accuracy, but also the immersions and emersions of
the solar spots; the inflection of light about the beginning and
ending of the annular formation ; and it will also be interesting
to observe what stars are visible. The barometer and ther-
mometer should be attended to, and experiments made on the
calorific effects of the solar rays on different bodies, regard
being had to the magnitude of the eclipse at the same time.
Moreover, the colour and shade of objects should be at-

* The instants are given in mean solar time according to the meridian
of that place.

Prof. Young on Vanishing Fractions. 295

tended to; and it may be proper to notice what effect the
gloom has upon animals and plants, &c.*
I remain, Gentlemen, yours, &c.
Epping, March 15, 1836. Tuomas SoQuire.

P.S. During the annular observation the light and heat
will be about zy of that of the full sun.

LXI. Observations upon Mr. Woolhouse’s Theory of Vanish-
ing Fractions. By J.R.Youne, Esq., Professor of Mathe-
matics in Belfast College.+

T was a remark of D’Alembert, that in all subjects except

in the mathematical sciences, there was room for difference
of sentiment. This exception, however, in favour of mathe-
matics was unadvisedly made by D’Alembert, as his own dis-
putes with Euler, on the subject of imaginary logarithms,
fully prove. Nor is this, the only mathematical topic upon
which very considerable difference of sentiment has prevailed.
The doctrine of vanishing fractions, a subject of far higher
interest and importance, has been the source of much more
keen and frequent controversy among mathematicians, and
respecting which doctrine there is by no means harmony of
opinion even at the present day; and this is a circumstance
doubtless to be regretted, because of the frequent and un-
avoidable occurrence of these fractions in various departments
of analytical research. To the aspiring student such con-
flicting theories in a part of the “ exact sciences” must be a
source of much perplexity. It must be embarrassing to feel
that if he assent to the reasoning of the profound Waring, he
must oppose himself to that of the cautious Maseres; and that
if he adopt the views of Professor Woodhouse, he must dis-
card the arguments of Dr. Hutton. It cannot, however, be
denied that the opinions of Waring and Hutton are those
which most accord with the ordinary views of modern analysts,
in reference to this subject; and it was scarcely to have been
expected that any mathematical theory should now be pro-
mulgated condemnatory of conclusions which, in the works
of our ablest modern analysts, wear all the aspect of mathema-
tical certainty. An essay has, however, been recently pub-
lished, by a very ingenious and able mathematician, embody-

[* Particular directions for observing an Annular Solar Eclipse, adapted
to every class of observers, and to the use of instruments of every degree
of perfection and power, will be found in Mr. Baily’s Memoir on the An-
nular Eclipse of Sept. 7, 1820,—Phil. Mag., First Series, vol. lv, p..85.—
Epit. |

+ Communicated by the Author,

296 Prof. Young’s Observations upon

ing statements and positions, in reference to this important in-
quiry, of a very peculiar kind, and which appear to me to be not -
only opposed to well-established truths, but calculated, under
the protection of his name, to retard—what I am sure that
gentleman is most anxious to promote—the spread of pure
scientific truth. It is from the same anxiety for truth that
I here venture, very briefly, to examine the more prominent
of the positions adverted to, and this I do with the same sen-
timents of respect and regard which I have long entertained for
his talents and friendship. I cannot, perhaps, in strictness,
say that my own defence requires that I should reply to the
animadversions which Mr. Woolhouse has made upon the
views which, in conimon with so many others, [ entertain on
the subject of vanishing fractions, although I think I am pri-
vileged to show that my friend has not supplied the place of
these views, which he has very unsparingly censured, by others
that will bear the test of careful examination. With many of
the observations in Mr. Woolhouse’s Essay I am disposed en-
tirely to agree, as being in strict accordance with the usual
notions of this doctrine; but the new theory, for which the
Essay is chiefly remarkable, seems to me to have been much
too hastily framed; it is embodied in the very general propo-
sitions which follow :

I. “ If, in any investigation of a geometrical problem, the
unknown quantity is expressed by a fraction which, in a parti-
cular case, becomes a vanishing one, the problem in that case
will resolve itself into a porism, and the value of the fraction,
or unknown quantity, will then admit of arbitrary assumption;
and a similar result will follow in all such cases, whatever be
the nature of the investigation.”

II. ‘* Whenever, in an analytical investigation, the resulting
expression for a quantity resolves itself into a vanishing frac-
tion, we may observe, as a general rule, that either one of the
original conditions of the inquiry becomes destroyed, or that
two or more of them become dependent, and, consequently,
whichever way it be, that there is at least one condition less
to fulfill, and that the vanishing fraction is not restricted to
any determinate value.” (Gentleman’s Diary, 1836, pp. 25, 26.)
That these propositions are fallacious, Mr. Woolhouse would,
I think, have soon seen, if he had attempted their demonstra-
tion, instead of contenting himself with testing their accuracy
by two particular examples, which, as far as they go, seem
indeed, at first sight, to corroborate their truth, although upon
examination such will not be found to be the case; and if we
were to interpret every vanishing fraction agreeably to this
theory, we should frequently be involved in the most pal-
pable errors. Indeed it is remarkable that my friend did not

Mr. Woolhouse’s Theory of Vanishing Fractions. 297

reflect that 2, occurring in an analytical result, was as likely
to be the symbol of absurdity, that is, of no value at all sub-
sisting under the proposed conditions, as the symbol of mul-
tiple values.

When we are operating with equations of the first degree,
containing several unknown quantities, the symbol $ is, in fact,
the very form which the result usually takes when the pro-
posed equations involve incompatible conditions; so that the
foregoing theory would lead us to infer an unlimited variety
of values, when in reality not one exists. ‘The theory which
Mr. Woolhouse condemns could never lead to such absurdity.
But even the examples which Mr. Woolhouse adduces do not
appear to accord with the doctrine which they are intended
to illustrate and enforce; nor do they furnish any ground of
objection to the theory they are designed to oppose. Of these
two examples the following is the one upon which, I believe,
Mr. Woolhouse places the most importance.

‘¢ To find a point in the arc of an elliptic quadrant, such
that, a tangent being drawn through it, the perpendicular
drawn from the centre to the tangent may be a mean propor-
tional between the two semiaxes a,b.” Now by putting x, y
for the coordinates of the required point, we easily obtain the
following equations, embodying the proposed conditions, viz.

Eyed y ae 1 x y
JERE cabs Tresabe hn ae

¢¢ and we find

so that the coordinates of the required point are

iN SH {MOTE bs,
e=ay/p y= NY fs

Now, although most persons would say that these results
furnish al/ the values of x and y legitimately deducible from
the preceding expressions for z* and y*, yet Mr. Woolhouse
adds, “* When 6 = a the elliptic quadrant becomes a circular
one, and these last expressions give for the position of the re-
quired point x = a 3, y = a 3, or the point which bi-
sects the arc of the quadrant. But in the case of the circle,
it is obvious that all its points will answer the proposed con-

Third Series. Vol. 8. No. 47. April 1836. aI

298 On Mr. Woolhouse’s Theory of Vanishing Fractions.

dition; and if we take the expressions which are immediately
deduced in the investigation, viz.

a(a—b) , &(a—d)

aoe? Y= ae?

we see that they become vanishing fractions in the case of the
circle, and do not limit the required point.” Now, I submit
that the values 7 =a 4/1, y = 3, are the true, and the only
values, fairly deducible from these vanishing fractions ; and that
the fact of the problem admitting multiple solutions, under the
proposed change of hypothesis, is altogether deduced from
other, and distinct, considerations. It is, in fact, information
which the analytical result is quite incompetent to supply ;- and
is derivable solely from an examination, not of the conclusion,
but of the original conditions of the problem. From this ex-
amination it appears that, in the proposed hypothesis, the two
conditions merge into one, and thus a restriction being re-
moved, the problem becomes indeterminate; but the mere
merging of the final result into the form 2, could never have
made known this ; the information is obtained quite independ-
ently of the slightest reference to this result, and from a di-
rectly opposite source. It is no doubt true, that when condi-
tions disappear, in certain hypotheses the results will assume
the form 2, but it is not true conversely; that when the results

assume the form 2, conditions must have disappeared, and

thus the values of ° become innumerable, as Mr. Woolhouse
contends, What would my friend say of the sum of a geo-
a(r"—1),
r—]
his second proposition above, this sum is anything! It ap-
pears to me that Mr. Woolhouse’s oversight, in his interpre-
tation of ° in the foregoing problem, is analogous to that
sometimes committed in physics; and which consists in taking
for cause and effect, two phenomena, not invariably con-
nected, yet both having a common antecedent. The very
thing (viz. the hypothesis a = 5) which causes 2° to become
9, causes also, in this case, one condition to disappear; and it
is thence presumed that there is an invariable connexion be-
tween these two events; whereas that connexion is purely ac-
cidental.
Belfast, March 16, 1836.

a

metrical series, viz.S = when7 = 1? According to

—-
Lond kE iin. Pik Mag. anak Tourn, of Science. Vo tA
6

SS ee
(7

[ 299 ]

LXII. On the Construction of Skew Arches. By
Cuartes Fox, Esq.*

[With a Plate. ]
atid bridges have hitherto been comparatively little used ;

but since railways have been introduced, in which it is
highly important to preserve as direct and straight a line as
possible, they are very frequently required, as a railway
passes through the various districts without the possibility of
regarding the angle at which it may cross canals and roads,
its course being in great measure controlled by the naturai
features of the country.

Wherever a canal is thus crossed at an angle, we must
either divert the canal, so as to bring it at right angles to the
railway; or we must build a common square bridge of suffi-
cient span to allow the canal, its course being unaltered, to pass
uninterruptedly under it; or we must erect a proper skew _
bridge. The first of these is often impracticable, as provisions
are generally inserted in the Acts of Parliament, for preserving
the canal from any alteration in its course; and even if this
were not the case, the diversion of a canal causes great expense,
and is attended with much inconvenience to its traffic: the se-
cond is a most unscientific mode of overcoming the difficulty,
and would also involve very serious expense, arising from the
necessity of making use of an arch of much larger dimensions
than would be required were the proper oblique arch erected
initsstead. By referring to Plate III. figs. 1 and 2, this will be
apparent: for this diagram I have selected the angle at which
the London and Birmingham railway crosses the Grand Junc-
tion Canal, being an angle of 30 degrees. It is for the above
reasons that oblique arches are now so frequently erected; and
a good method of building them is, therefore, of considerable
importance.

As many practical men with whom I am acquainted have
experienced considerable difficulty in the construction of
skew bridges, I was led to turn my attention to the subject ;
and haye at length succeeded in rendering the principles of
it easy to be understood.

All persons are acquainted with the manner in which com-
mon square arches are built, where all the courses are square
to the face, and parallel both to the direction and surface of
the road or river running under it, by which means the thrust
or strain is always at right angles to the joints or beds of the

* Communicated by the Author.
212

300 Mr.C. Fox on the Construction of Skew Arches.

individual stones composing the arch; hence the whole thrust
of ordinary arches, which is brought in upon the abutments,
is exerted in the direction of the bridge itself, z. e. of the road
passing over it.

To devise some simple mode of setting out and working the
courses of stone in a skew arch, so as to bring in the thrust
in the proper direction, was the great object to be obtained.
All practical men are aware of the vast difference between
having to deal with straight and with twisted Jines; and the
necessity of introducing twisted lines in the construction of
skew bridges will soon be seen.

In skew bridges, in order to keep the thrust in the proper
direction, it is necessary to place the courses of stones at an
angle with the abutment, whereby each stone loses its paral-
lelism with the surface of the road, and is therefore laid on
an inclining bed.

In a common semicircular arch each course of stones is
parallel with the axis of the bridge, and all the beds are
wrought so as to point to the axis: the inclination of the stones
varies in every course; but although the inclination of the
stones varies in every course, both ends of the course have
the same inclination, both ends are equally high in the arch,
and both ends point to the centre. This is the case in the
ordinary bridge; but in a skew bridge, as the courses run
obliquely across the arch, one end of the course is necessarily
higher up the arch than the other, and therefore would no
longer point to the centre; but only make this point to the
centre, and we immediately get the twisted form, that is, we
make each bed of the courses of stones a true spiral plane.

The principle which I have adopted is, to work the stones
in the form of a spiral quadrilateral solid, wrapped round a
cylinder, or in plainer language the principle of a square
threaded screw; hence it becomes quite evident that the trans-
verse sections of all these spiral stones are the same throughout
the whole arch. It will be obvious that the beds of the stones
should be worked into true spiral planes; but I am not aware
that any rule has yet been published that would enable the
stones to be wrought at the quarry into the desired form, or of
any rule by which the true angle at which the courses cross the
axis of the bridge is determined. Tig. 3. is a representation of
the courses of the stones, each alternate course being omitted
in order to show their form more distinctly; and the course
forming the key-stone is carried out so as to show that it
really is the thread of a square threaded screw wound round
a cylinder, the cylinder being indicated by the two dotted
lines. If the threads are cut at right angles to the cylinder,

Mr. C. Fox on the Construction of Skew Arches. 301

the section would appear as in fig. 4; if cut at right angles to
the courses, or as nearly so as the case will admit of, as they
are really cut to form the face of the bridge, the section would
appear as in fig. 5.

In order that these principles may be understood, it is ne-
cessary to have aclear idea of the nature of a spiral plane; and
perhaps, the best definition of it is, to consider it as being
produced by the twofold motion of the radius of a cylinder,
2. é. let a radius revolve upon its axis at an uniform velocity,
and at the same time impart to it a progressive motion along
the axis itself, and then by apportioning these two motions to
the particular case you will obtain any spiral you may desire;
hence it is apparent that the outer edge of a spiral plane is
produced bya straight line wound round a cylinder every-
where forming the same angle with the axis, while the inner
edge actually merges into the axis itself, which of course is a
straight line. The question which now naturally suggests it-
self is how to decide at what angle to place these spiral stones
with respect to the axis of the bridge, or in mechanical lan-
guage, what traverse must we give the screw ?

In entering upon the investigation of this subject, my first
idea was to develop upon a plane surface all the superficies
connected with a skew arch.

If a semi-cylinder be cut obliquely, the section is a semi-
ellipsis, and if the semi-cylinder be then unfolded, the edge
of the developed ellipsis will not be a straight line but a spiral
one; and some builders not being aware of this fact, have
squared a course from the face of the centring, and having
drawn in the remaining courses parallel with this, have taken
it for granted that all the courses would be square with the
face, which it will be seen is impossible by referring to the de-
velopment of the intrados, or under surface of the arch, which
is the development of the centring itself: they have hereby
been led into very serious and perplexing difficulties.

Having shown the impossibility of making all the stones
square to the face, I will now give the mode of deciding in
what direction they should be placed. When the soffit is
developed, the edge which formed the face of the arch gives
a true spiral line: my first plan was to lay the courses of
stone at right angles to a line extending between the two ex-
treme points of the spiral line of the developed soffit (see
fig. 6); this line I shall afterwards speak of as the approxi-
mate line, as it is the nearest approximation to the line of the
face that can be obtained by a straight line.

On further consideration I discovered a far more eligible
mode of laying out the lines,

302 Mr. C. Fox on the Construction of Skew Arches.

It is evident from fig. 7, that if spiral planes are considered
as composed of spiral lines placed at various distances from
the centre of the cylinder, each of these lines will form a
different angle with the axis; and therefore, as an arch has
always some thickness, that although we have the inner edge
of the spiral plane placed at right angles to the thrust, yet
every other portion is gradually departing from a right angle,
and is, therefore, exerting its force in an improper direction:
thus an arch of this description can never exert its thrust in
the direction of the bridge, but is endeavouring to push the
abutments obliquely.

To get the thrust strictly correct, I have supposed the arch
to be cut into two rings of equal thickness (see fig. 8); and
having considered the external ring as removed, have pro-
ceeded to develop the outside surface of the remaining one:
this I shall hereafter speak of as the intermediate develop-
ment, as it is the development of a surface midway between
the extrados and soffit or intrados.

Upon this intermediate development I place the approxi-
mate line, and then draw all the courses square to it; by which
means we obtain a line in the centre of each stone exerting its
force in the true direction, and thus get rid of the disadvan-
tage of twisted beds to the stones, as in proportion as the one
half of this bed exerts its force in an oblique direction on
the one hand, the other half acts in the opposite direc-
tion, and is therefore always producing a balance of effect,
which resolves the various forces into one exerting all its
power in the true direction, which is the object to be ob-
tained.

Having explained the mode of setting out the beds of the
stones, a little may now be said on the situation of the cross-
joints: by these will be understood the joints between the va-
rious stones constituting a complete course.

Where an arch is built of stone throughout, the situation of
these joints is of minor importance; but where stone is expen-
sive, it is common to make the faces of the arch only of stone,
filling in the intermediate space with brick-work; as in these
instances the cross joints form the boundary between stone-
and brick-work, it becomes a point of considerable importance.
This is the case in the Watford viaduct; each stone here is
equal in thickness to five courses of bricks, so that there are
five thicknesses of mortar in the brick-work to one in the
stone. Mortar always is compressed into a smaller compass
when the centring is struck, and the full weight of the arch
comes upon it. In consequence of this tendency, that por-
tion of arches constructed of brick-work, always subsides much

Mr. C. Fox on the Construction of Skew Arches. 303

more than the stone. In an arch where stone- and brick~
work are combined, little reliance should be placed on their
connexion, as this is always more or less disturbed after the
centring is removed, so that we should endeavour to con+
struct each portion of the arch with its bearing surfaces or
beds as nearly equal as possible.

In the first models the soffits of all the stones were made of
an equal length, considering that this would present the best
appearance; but this method rendered the bearing surfaces
very unequal, as will be seen by fig. 9; the equal lengths
being indicated by the dotted lines.

This difficulty is overcome by this simple means: instead of
having the stones of equal length on the soffit, they are made
so on the intermediate development, and then the areas of
the bearing surfaces or beds of the stones are all equal. See
fig. 10.

“Having given the mode of laying out the lines, I will now
proceed to the practical part, viz. the working of the indivi-
dual stones.

My first idea was to commence by working the soffit; and
this was the mode employed.

Having obtained an elastic mould cut to the angle at which
the joints of the soffit cross the axis of the bridge, the work~
man by means of this gets an oblique line on that surface of
the stone which he intends for the soffit. It will be under-
stood from fig. 11, that this oblique line thus obtained will be
parallel with the axis of the bridge. The workman then pro-
ceeds to chisel out a groove (or what is by masons called a
chisel-draught) along this line, of sufficient depth for what he
knows will be required for the hollowing of the stone.

He then takes two wooden moulds (one of which is shown
in fig. 12), which are portions of the same circle as the soffit
itself. A mark being placed upon the centre of each of these
moulds, the workman then proceeds to sink them into the
stones at right angles to this chisel-draught, (see fig. 11,) and
in such a manner that the centre marks shall be in the chisel-
draught, and the upper edges of the moulds, which are straight,
shall be in the same plane, or what is commonly called, out
of winding. It will now be obvious that these two last grooves
will form true portions of the soffit itself, and therefore, that
the workman has nothing to do but to work out the remainder
of the stone with a straight edge, always kept parallel with
the first draught, and sunk to the bottom of the two draughts
which were worked by the curved moulds. Having ob-
tained this hollowed surface, an elastic mould, of the exact
size of the soffit of each stone, is pressed into it, by which

304 Mr. C. Fox on the Construction of Skew Arches.

the stone being marked, we obtain all the lines of the soffit
itself.

It will now be quite evident that the beds may be obtained
by making use of a square, one limb of which shall be made
to the curvature of the soffit, and the other the radius of this
curve; always taking care that this square is kept at right
angles to the axis, as will be seen in figures 13, 14, and 15.

The first few stones were wrought in this manner; but
finding it very difficult to prevent the workman from getting
his soffit a little on one side, by which means he wasted much
of the stone on one bed and rendered the other deficient,
I had recourse to a method which I will describe. Having
provided two straight edges, the one parallel and the other
containing the angle of the twist, (see fig. 16,) we proceeded
to work one of the beds by chiselling two draughts along the
stone, so that these straight edges being kept at a proper di-
stance from each other were let into the stone until they were
out of winding on their upper edges.

Having finished one'bed by straight edges, we then ob-
tained the soffits and other beds by means of the square be-
fore mentioned. By working a bed first instead of the soffit,
the best will always be made of a block of stone.

As we have before seen that all the stones constituting a
skew arch are portions of the same square threaded screw,
the workman having finished one stone has only to repeat the
same operations with every other.

Any stone in the face of the arch, taken from one side, and
applied to the corresponding one face to face, will continue
the true spiral plane: this fact enabled us to work all the
stones for one bridge in pairs; that is, one stone having been
wrought with the proper twist, and of sufficient length to make
. two stones, was accordingly sawn in two at the proper angle:
but of course this cannot be done advantageously when the
stone is of a very hard nature.

It has been shown that by developing all the various sur-
faces, instead of having to think of complicated spiral lines,
they are at once reduced to straight ones; and I will now very
briefly show how simply the data necessary for the construc-
tion of a skew arch may be obtained (see fig. 17).

Let A represent the curvature of the intrados, and C the
extrados, B being a line midway between A and C. Let
DD, EE, F F represent the boundaries of three cylinders of
which A, B, C are the transverse sections; let these cylinders
be cut by the straight line G, H, at the angle of askew, that
is, the angle formed by the two roads crossing each other ;
and from the points I, J, K, draw three straight lines at right

Prof. Powell on the Theory of the Dispersion of Light. 305

-angles to the axis, and of such lengths that I L shall be of
equal length to the semicircle A, and J M equal to B, and KN
equal to C; from the point O draw the straight line O L, and
‘also from P to M: it will be seen that O L is the approxi-
mate line of the developed soffit, and P M that of the inter-
mediate development. Add Q, R, and S, which are the centre
lines of the three developments.

It will be seen that when these developments are placed as
in an arch, these three lines Q, R, S_ being parallel with the
axis, will be in a plane perpendicular to the axis, and, there-
fore, that all the points in each spiral will be vertical with the
axis, and also with one another.

Through any point in P M draw a straight line V at right
angles with P M, which straight line shall extend to the axis
of the cylinder.

At the point where it intersects R, a line T perpendicular
to the axis intersects Ralso: this last perpendicular line cuts
the three lines Q, R, S at the points where the lines U, V, W,
which meet in X, intersect Q, R, S.

The joints are then drawn upon the three developments
eee with the lines U, V, W, and at such distances that the
ines Q, R, S shall be cut into equal parts. Of course, care
must be taken to divide the approximate line of the soffit into
a given number of stones. ‘The angle X will be that which
the intrados form with the axis of the cylinder, and the angle
U W will give the wind of the bed. On this principle and
by the rules here given, it is nearly as easy to work the stones
of a skew bridge as those of any other.

Park Village East, London, March 17, 1836.

LXIII. Further Observations on M. Cauchy’s Theory of the
Dispersion of Light. By the Rev. Bapen PowELt, M.A.,
E.R.S., Savilian Professor of Geometry, Oxford.

(Continued from p. 28.)

I PROCEED to illustrate the further researches to which
I alluded in my last paper; relative to the development of
the theory of dispersion, and simplifying the process of M.
Cauchy.

In order to consider the subject in its simplest form, let us
confine our attention to a plane wave perpendicular to the
axis of z, with vibrations parallel to the axis of y. Then the
displacements § and ¢ will vanish, and the differential equation

306 Prof. Powell’s further Observations on M. Cauchy’s_

of motion deduced upon M. Cauchy’s principle (in my ana-
lysis, eq. (12.),) will be reduced to

f (7 os? ?
Fh HS { mith) 4, Ve (1.)

where 7 is the value, at the time ¢, of the varying displacement
of the molecule m, whose rectangular coordinates when in
equilibrium are x y z34+Avy is the displacement at the same
moment ¢, of another molecule m, which has for its rectangu-
lar coordinates when in equilibrium

rt+Ac ytAy z+Az, while
r= V/ Aa’ + Ay? + Az’,
or the distance between these two molecules in their positions
of equilibrium; £8 is the angle between this distance r and
the axis of y; and, finally, f(r) and f(7) are functions of 7, of
which the former (if positive) expresses the law of attraction,

or (if negative) the law of repulsion, and the latter is derived
from it by the rule

FitD = 7 P zr). —T(7-
S, the sign ef summation, is relative to the actions (attractive
or repulsive) of all the molecules m.

I have recapitulated thus far in reference to what was esta-
blished at the outset of M. Cauchy’s investigations. “Now this
analysis is thus far devoid of all difficulty or intricacy ; the
whole difficulty of the subject lies in the zntegration of these
equations of motion. The integration given by M. Cauchy
is of an extremely general kind: but for the purpose we have
now more immediately in view, it will be readily allowed that
if a particular solution were proposed, such as to include the
establishment of the relation between » and A, it would suffice.
A valuable instance of a method of effecting such a simplifica-
tion has been laid before the readers of this Journal, in the
excellent paper of Mr. Tovey in the Number for January, p. 7.
But another such particular solution has been pointed out
by Sir W. R. Hamilton, the nature of which I now proceed
to describe ; and this will be most perspicuously done in the
following manner:

It will be easily seen that all the conditions of a wave for
the ordinary phenomena are fulfilled by such a function as

4 = A+Bcos (<7 we-) +C sin (= (we—t)); (2)

Theory of the Dispersion of Light. 307

which, merely by the assumption of the coefficients and trigo-
nometrical operations, is easily put under the form

2a
7 = % +7, COS es (u2—1+ 0), (3.)
t) being entirely arbitrary, and 7 4, being also arbitrary, but

small ; 7) is introduced only for greater generality.
Differentiating in respect of ¢, we shall have

@ Qn\2 2:
oy =— (=) 4, COS (= (e—t+4)). (4)
Also, by the method of finite differences, we have
2 2
—2 xn, cos (= (ea—t+t) ) (sin res)

Ayj= bide erure (5.)
— sin (= (we—-t+t,) (sin tad hv *)

a

Now (on precisely the same grounds as those adverted to
in the analysis of Cauchy for deducing the equations (22.),)
it will be seen that this expression is of such a form that if it
were introduced in a summation, since we may assume half
the values of A x as positive and half as negative, the second
member involving the first power of the sine of a function of
A, and the first member the square, the sums of all the
values in the second member will destroy each other, but not
those in the first.

Thus on substituting this value of A in the differential
equation (12.), or that above, (1.), we shall only have to take
into account the first member, multiplied by the function of
(vr); and it will thus easily appear that that equation (1.) is
satisfied by these values derived from the assumed equation
of the wave (3.), provided we suppose

(22) = 8 {2m LO + PASE (ain HAF) 1, (6,

or, in other words, the equation (3.) coupled with this last
condition (6.) is a particular solution of the differential equa-
tion of the motion of a system of molecules (1.).

But also, this equation (6.) involves the relation between r

- A 1 2
and », (or between A and p, since we have — =—,) which
y- ee pia?

is expressed by writing, for abridgement,

308 Prof. Powell’s further Observations on M. Cauchy’s

mh AX ae
v

f(r) +o08° BS (1), 4° — ye hfe
‘ J

Mm
and —
2g

(though H? is not necessarily positive), which, since
Qa 6

Ue a Ae

will give the relation

is sin 6 y?
Gye id rad i, (8.)
the same as that formerly deduced.

Such is the outline of the simplification proposed: I have
only to regret that these and the other researches connected
with the same subject have not been brought before the public
by the author himself in the more complete form in which he
could have clothed them. But, as they are, I trustneither he
nor the mathematical reader will think I have done wrong in
adopting this mode of availing myself of his permission to
make use of them. On the same ground I will add another
brief investigation from the same source connected with the
fundamental formula of dispersion.

I have before observed that for low dispersive substances,
at least, the simple approximate formula appears quite suffi-
cient. As it may, therefore, be useful for a very large num-
ber of cases, it will not be unimportant to dwell upon it, and
to state a very simple practical rule resulting from it, which
completely removes the difficulties of the computation as con-
ducted by the methods I formerly adopted.

In the first place, from the nature of the formula the fol-
lowing considerations will be readily evident. Taking any two
rays whose indices are » p,, and length of waves A A,,_ let us
write the arc

meCosd _

* = 6.
Then we have sigicos ys = gm
A A

7

and by the approximate formula

Theory of the Dispersion of Light. 309

1 in 6
~= (Ss );

1 sin( bie
conegn are)

Then developing the sine and dividing by the arc
] 7 NS
1 — at i] cw +,&c.

—--_—
De cans, iy, 23ce
And for a first approximation, neglecting the terms above two
dimensions, this will be easily reduced to

re 6? Gi78

soe sida akg

By 6 6 A;
whence we obtain

iz.
yin (1— 7)
Ar.2
‘San
Hence the practical method referred to will be as follows:
Let there be assumed a subsidiary arc $ such that

be

6
log 6 = } log faya] + log sin 9.

a,
And since i. = sec® ¢, we have also

log. sec. = 3} (log pw, — log p).

These logarithmic formulas enable us to perform the ap-
proximate calculation with the greatest ease.

[ 310 ]

LXIV. Proceedings of Learned Societies.
GEOLOGICAL SOCIETY.
Anniversary Proceedings, February 19th, 1836.

FTER the usual Reports had been read, (which are printed in
the “ Proceedings ” of the Society,) the President announced the
award of the Wollaston Medal and Proceeds for the past year; and, in
doing so, said,
GENTLEMEN,

You havelearnt from the Report of the Council that the Wollaston
Medal has been awarded to Mr. Agassiz of Neuchatel for his work
on Fossil Ichthyology, and that the sum of 25/. from the Donation
Fund has been awarded by the Council to Mr. Deshayes in promo-
tion of his labours in fossil conchology. I shall now proceed to re~
quest Mr. Broderip to communicate this adjudication to his friend
Mr. Agassiz, and I shall deliver in charge to our Foreign Secretary,
Mr. De la Beche, the sum which has been voted to Mr. Deshayes.

The President then addressed Mr. Broderip in these words :-—

Mr. Broprrip,

I have great pleasure in requesting you to inform Mr. Agassiz, of
Neuchatel, that the Council of the Geological Society have awarded
the Wollaston Medal to him for his work of last year on Fossil Ich~
thyology. Ona former occasion we presented the proceeds of the
Donation Fund for one year to the same distinguished naturalist, to
assist him in the publication of the early part of his great work, the
importance of which was then only beginning to be known to the
scientific world.

It will ever be a subject of gratification to us to have learnt that
this small pecuniary aid was not without its influence in accelerating
the publication of his ‘“ Researches on Fossil Fish,’ arriving as it
did opportunely at a moment when the funds which could be appro-
priated for the undertaking were nearly exhausted. Mr. Agassiz
acknowledged at the time his obligation to us for a mark of
sympathy and regard which he received so unexpectedly from a
foreign country, and which cheered and animated him to fresh ex-
ertions. You will have the kindness to acquaint him that the
Council in now awarding the Medal to him, are desirous that he
should possess a lasting testimony of their esteem and of the high
sense which they entertain of the merit of his scientific labours.

Mr. Broprrip replied,—

Srr.—I accept the trust: and permit me, on the behalf of Pro-
fessor Agassiz, to offer his best thanks to the Society for the seal
which it has this day set on the powerful zoological lever which he
has placed in the hands of Geologists.

This crowning gift will be doubly precious to him when he reflects
on the high character of those who have awarded it, and hears of
the expressions with which you, Sir, have been pleased to accom-
pany it.

These, he will feel, are the incentives

“ that the clear spirit do raise
To spurn delights and live laborious days.”

Geological Society. 811

He will look upon the illustrious head that gives dignity to the
gold—upon the representation of ‘that dark eye” before whose
glance, as it has been eloquently said by one of your predecessors,
all false pretensions withered—and the sight will inspire him
with new energies.

The President then addressed Mr. De la Beche in these words :—

Mr. De ta Becue,

It is now my duty to deliver into your hands as Foreign Secretary
of this Society the sum of 25/., and it is with great satisfaction that I
request you to inform Mr. Deshayes of Paris that this portion of
the proceeds of the Wollaston Donation Fund has been awarded to
him by the Council for the promotion of his labours in Fossil Con-
chology. I beg that you will express to Mr. Deshayes at the same
time how highly we appreciate the services which he has already
yendered to Geology by his description of the fossil shells of the
strata above the chalk, to which he has chiefly, although not exclu-
sively, devoted his attention ; and we rejoice to hear that he is now
engaged in the investigation of the fossil shells of the older for-
mations.

We are not ignorant that he has prosecuted his scientific studies
with zeal and enthusiasm under circumstances of considerable dif-
ficulty ; and we trust that the notice thus taken of his labours may
encourage him to persevere in devoting the powers of his mind and
his great acquirements to a department of science so eminently
subservient to the advancement of Geology.

Mr. Dr 1a Becne on receiving the donation expressed the plea-
sure which it gave him to be requested to communicate the intelli-
gence to Mr. Deshayes, and the satisfaction which he felt in pub-
licly avowing his approbation of the award of the Council.

The following gentlemen were elected the Officers and Council for
the ensuing year.

Orricers.—President, Charles Lyell, jun. Esq. F.R.S. & L.S.:
Vice-Presidents, Rey. William Buckland, D.D. F.R.S. Professor of
Geology and Mineralogy in the University of Oxford ; Sir Philip de
Malpas Grey Egerton, Bart. M.P. F.R.S. ; George Bellas Greenough,
Esq. F.R.S. & L.S.; Edward Turner, M.D. F.R.S, L. & E. Professor
of Chemistry in the University of London: Secretaries, William John
Hamilton, Esq. ; Woodbine Parish, jun. Esq. F.R.S.: Foreign Secre-
tary, Henry Thomas De la Beche, Esq. F.R.S.& L.S.: Treasurer, John
Taylor, Esq. F.R.S.

Counciz.—Francis Baily, Esq. F.R.S. & L.S.; William John
Broderip, Esq. F.R.S. & L.S.; William Clift, Esq. F.R.S.; Sir A.
Crichton, M.D, F.R.S.; William Henry Fitton, M.D. F.R.S. & L.S.;
Henry Hallam, Esq. F.R.S.; Robert Hutton, Esq. ; Roderick Impey
Murchison, Esq. V.P.R.S. F.L.S.; Viscount Oxmantown, F.R.S. ;
John Forbes Royle, Esq. F.L.S.; Rev. Adam Sedgwick, Woodwardian
Professor in the University of Cambridge, F.R.S. & L.S.; Lieut.-Col.

$12 Geological Society.

W. H. Sykes, F.R.S. & L.S. ; Henry Warburton, Esq. M.P. F.R.S.5
Rev. William Whewell, F.R.S.& L.S.

The President subsequently delivered the following

ADDRESS.
GENTLEMEN,

You have learnt this morning, from the annual report of the
Council, that the financial affairs of the Society continue to flourish;
and that since our last anniversary we have published the conclud-
ing part of the third volume of our Transactions, and the first part
of a fourth volume. Another part of the same volume is nearly
ready, and the Council have directed their thoughts seriously to the
means of preventing, in future, the accumulation of such heavy
arrears of unpublished memoirs. The delays have hitherto arisen
from a desire to print all papers containing original and valuable
matter in the order in which they were presented; but many have
been sent to us in so unfinished a state as to retard the printing of
the rest, and, as the science advances rapidly, and new facts pour in
daily, the authors even of the most finished memoirs soon require
to make additions and corrections, and thus the evil is continually
augmenting. ‘The Council have therefore resolved, for the future,
to print at once those memoirs which are in the most complete
state, without waiting for others which are imperfect.

During the last year there have been elected into the Society 45
new members, and we have lost 4 by resignations and 12 by deaths.
Among the names of the deceased Fellows I may mention those of
Mr. Goodhall and Mr. Mammatt as having zealously contributed to
the progress of our science. Mr. Goodhall was an active collector
of British fossils, and to his labours we owe many valuable contri-
butions to our museum, and the discovery of shells of new species
figured in Sowerby’s Mineral Conchology. The work of Mr. Mam-
matt, on the Coal-field of Ashby-de-la-Zouch, has been honourably
mentioned by my predecessor Mr. Greenough, in his last anniver-
sary speech. Mr. Mammatt had superintended, for more than thirty
years, the working of extensive coal mines, and kept a record of the
details of various sections with which he was practically acquainted.
To these documents he has added several plans of remarkable faults
which intersect the carboniferous strata of Leicestershire. He has
shown that on one side of one of these faults the beds rise to the
height of 500 feet above the corresponding beds on the other side,
yet the mass of uplifted strata does not project above the gene-
ral level of the country. He infers, therefore, that it has been
removed by denudation, and that the wreck of it alone now:
remains on the surface in the shape of sand and boulders. Mr.
Conybeare has drawn similar conclusions respecting analogous phz-=
nomena observed on a still greater scale in the Newcastle coal di-
strict.* Whether the denudation was sudden or gradual, or whether
the faults were produced at once or were the result of a series of
movements, are points which the limits of this discourse will not

* Report on Geology to the British Association, 1832.

Geological Society. 313

allow me to discuss at present. Mr. Mammatt contends that these
enormous shifts were not effected by volcanic convulsions, but simply
by a quiet and uniform operation accompanying the desiccation,
shrinking, and induration of dense masses of argillaceous and other
rocks, an opinion which, however ingenious, seems irreconcileable
with the evidence of violent disruption with which this and other
coal-fields abound. Mr. Mammatt’s volume is illustrated by more
than one hundred plates of fossil plants, but it is much to be re-
gretted that before executing such costly illustrations the author did
not obtain the assistance of a skilful botanist, who might have selected
the most important and might have added descriptions, without which
mere figures can scarcely ever convey accurate information.

Early in the spring of last year an application was made by the Mas-
ter General and Board of Ordnance to Dr. Buckland and Mr. Sedg-
wick, as Professors of Geology in the Universities of Oxford and Cam-
bridge, and to myself, as President of this Society, to offer our opi-
nion as to the expediency of combining a geological examination of
the English counties with the geographical survey now in progress.
In compliance with this requisition we drew up a joint report, in
which we endeavoured to state fully our opinion as to the great ad-
vantages which must accrue from such an undertaking, not only as
calculated to promote geological science, which would alone be a
sufficient object, but also as a work of great practical utility, bear-
ing on agriculture, mining, road-making, the formation of canals and
rail-roads, and other branches of national industry. The enlight-
ened views of the Board of Ordnance were warmly seconded by
the present Chancellor of the Exchequer, and a grant was obtained
from the Treasury to defray the additional expenses which will be
incurred in colouring geologically the Ordnance county maps. This
arrangement may justly be regarded as an economical one, as those
surveyors who have cultivated geology can with small increase of
labour, when exploring the minute topography of the ground, trace
out the boundaries of the principal mineral groups. This end, how-
ever, could only ke fully accomplished by securing the cooperation
of an experienced and able geologist, who might organize and direct
the operations: and I congratulate the Society that our F oreign
Secretary, Mr. De Ja Beche, has been chosen to discharge an office
for which he is so eminently qualified.

At the same time that measures are thus in train for complet-
ing a Geological Map of England on a magnificent scale, the Map
of Scotland, by Dr. MacCulloch, which has been so long and im-
patiently expected, is at length on the eve of publication. But at
the moment when I can announce this welcome intelligence we
have to deplore the sudden loss of this distinguished philosopher.
The first paper in the first volume of our Transactions was from
the pen of Dr. MacCulloch, and subsequent volumes contain no
less than eighteen of his memoirs*. It would lead me far beyond

* [Three of these papers by Dr. Macculloch will be found at large in Phil.
Mag. First Series : viz. ‘¢ On the Sublimation of Silica,” in vol. lxiv. p. 441;
“ On Staffa,” ibid. p. 445 ; and “ On certain Products obtained in the Di-
stillation of Wood,” in vol. xlv. p. 203.]

Third Series. Vol. 8..No. 47. April 1836. 2K

$14 Geological Society.

my present limits were I to attempt to give a general analysis of
these, and of his numerous other works on geology, such as his
Western Islands and his Classification of Rocks. The infiuence
exerted by them on the progress of our science has been powerful
and lasting, yet they have been less generally admired and studied
than they deserve. Their popularity has been impaired by a want
of condensation and clearness in the style, a defect which no one
could more easily have remedied than the author, had he been
willing to submit to the necessary labour. Another blemish has
also contributed to give a repulsive character to some of his later
productions, especially his System of Geology, the absence, or ap-
parent absence, of all enthusiasm and love for his subject, anda
disposition to neglect or speak slightingly of the labours of others,
and even to treat in a tone bordering on ridicule some entire depart-
ments of science connected with geology, such as the study of fossil
conchology. I attribute these imperfections principally to habitual
ill health acting upon a sensitive mind, for certainly, Dr. MacCul-
loch’s spirits were much depressed by bodily sufferings when I
had first the pleasure of knowing him, about the year 1822. His
imagination was then haunted with the idea that his services in
the cause of geology were undervalued, and it was in vain to com-
bat this erroneous impression. After that period he almost entirely
withdrew himself, even when residing in London, from all personal
intercourse with the most active geologists; and to those who knew
him this seclusion from scientific society was a subject of frequent
regret. Having expressed myself thus unreservedly on some of the
peculiarities and defects of his style, I may affirm that as an origi-
nal observer Dr. MacCulloch yields to no other geologist of our times,
and he is perhaps unrivalled in the wide range of subjects on which
he displayed great talent and profound knowledge. For myself I
may acknowledge with gratitude that I have received more instruction
from his labours in geology than from those of any living writer.
One of the most important communications which we have re-
ceived for many years is an essay by Professor Sedgwick on the
changes of structure produced in stratified rocks after their deposi-
tion. Respecting the magnesian limestone, he has confirmed by
new arguments the conclusions which he formerly drew, in proof
that the complicated concretions of this rock have been pro-
duced since the original deposition of the beds. But the principal
part of his memoir is devoted to the description of the cleavage or
slaty structure of rocks, and those partings which have been called
joints. The author first shows the analogy of the Cumbrian zone of
green slate and porphyry with the structure of the principal chain
of North Wales. In these regions, as in part of the slaty series of
Westmoreland and Lancashire, occur many beds exhibiting a slaty
cleavage, which the Professor distinguishes from a jointed structure.
Joints, he says, are fissures placed at definite distances from each
other, the masses of intervening rock having no tendency to cleave
in a direction parallel to such fissures: whereas in the planes of
cleavage, the rock is capable of indefinite subdivision in a direction

Geological Society. 315

parallel to such planes. The planes of stratification, on the other
hand, are perfectly distinct from both, and throughout the district
alluded to have never been found to coincide with the lines of cleav-
age, dipping sometimes to the same point and sometimes to opposite
points of the compass, but being always inclined to them at an angle
of from 10° to 30° or 40°, and inno instance at 90°. There are re-
gions in North and South Wales thirty miles in extent, and many
miles in breadth, where the cleavage planes preserve an undeviating
dip and direction notwithstanding that they traverse strata which
are greatly contorted. —

In that variety of slate-rock which is used for roofing, all traces
of original deposition or stratification are often obliterated ; yet in
many quarries, a number of parallel stripes are discovered, sometimes
of a lighter and sometimes of a darker colour than the general mass.
These stripes, says the Professor, are universally parallel to the
true beds, whenever such beds can be discovered, whether by or-
ganic remains, by the alternations of similar deposits, or other
ordinary means. Many of these beds are of a coarse mechanical
structure, others are fine chloritic slate; but the coarser beds and
the finer, the twisted and the straight, have all been subjected to
one change, a crystalline cleavage passing alike through all. Some
of the sections given show the cleavage planes preserving an almost
geometrical parallelism while they pass through curved strata, of
which the sedimentary origin is obvious. In another place it
is said that where the slaty cleavage is very perfectly brought
out the rocks always make an approach to homogeneity, but where
the coarse beds predominate the slaty structure almost entirely dis-
appears. Dr. Boase in his comments on these passages has re-
marked that they seem inconsistent with each other, and I confess
that at first they struck me in the same light ; but the Professor has
explained to me that although the coarse beds are not slaty, they
have a grain parallel to the cleavage planes of the finer beds, this
grain being exhibited when they are struck with the hammer; and it
is only when the materials of the beds are very coarse that the
cleavage planes entirely vanish. :

In regard to the origin of these phenomena, the author supposes
that crystalline or polar forces must have acted on the whole mass
simultaneously in given directions, and that the action being carried
on at once through a very large mass of matter may have acquired
an accumulated intensity of crystalline action in each part, so that
the whole intensity of crystalline force, modifying the mass, may
not have been equal to the sum of the forces necessary to crys
stallize each part independently, but may have been some function
of that sum whereby it may have been increased almost indefinitely.

I regret that I have not space to do justice to this ingenious
speculation, nor have I yet had sufficient opportunities of obser-
vation to know whether we shall be able to distinguish generally,
with precision, those slates which are diagonal to the strata, from
those flagstone-slates, as it is proposed to term them, which are pa-
rallel to the layers of deposition. Pe the lastsummer I observed

2K 2

316 Geological Society.

in the Swiss Alps that the fissile roofing-slate and drawing-slate of
the Niesen, in the Canton of Berne, divides into extremely thin la-
minz, which are parallel to the true planes of stratification. The
direction of the beds is shown by alternations of coarse and clearly
mechanical strata of a kind of greywacke, the whole series belong-
ing to the Green Sand or fucoid grit formation. Ifit be said that
these slates may owe their laminated texture to extremely minute
flakes of tale, mica, or some other foliated mineral which may have
fallen as sediment and have been all deposited on their flat surfaces,
I reply, that in that case they would exemplify the exact similarity
of certain acknowledged slates of deposition to others which have
originated in crystalline forces independent of sedimentary action.
Mr. Murchison, after confirming the truth of the Professor’s obser-
vations as applied to all those regions of Wales which have come
within his survey, has pointed out what might by some be considered
an exception to the rule in a part of the slate-rocks of Pembroke-
shire, where the planes of slaty cleavage are coincident with the
true lamin, as proved by colour and the alternation of various
layers of deposit. Mr. Murchison states, however, that although
these rocks are quarried as roofing-slates, and are a part of the older
system, they may be classed by Mr. Sedgwick as fine flagstones.

Some confusion will, I fear, arise from attempting to restrict the
term slate to those cases alone where the cleavage is oblique to the
stratification ; but whatever nomenclature we adopt, it is clear from
the excellent paper of the Professor, that three distinct forms of
structure are exhibited in certain rocks throughout large districts :
namely, first, stratification ; secondly, joints; and thirdly, slaty
cleavage; the last having no connexion with true bedding, and
being superinduced by a cause absolutely independent of gravita-
tion. These different structures must have different names, even
though there may be cases, and I believe there will be many, where
it is impossible, after carefully studying the phaenomena, to decide
upon the class to which they belong.

One curious consequence, but slightly alluded to by the author, ap-
pears to follow from the facts described, namely, that the slaty struc-
ture must have commenced at a period posterior to the last series of
violent movements which dislocated the strata and threw them into
anticlinal and synclinal lines. Such disturbances would have de-
ranged the parallelism of the cleavage planes. If, therefore, there
are proofs, as I believe there are, of the elevation or subsidence of
these rocks since they assumed the slaty structure, the whole
country must have been moved bodily, or the separate masses,
if they changed their relative position, must have moved in such
directions as to allow the dip of the cleavage planes to remain un-
altered.

It is with pleasure that I next call your attention to the investi-
gations which Mr. Murchison has been steadily pursuing in the
older fossiliferous rocks of Wales and the bordering counties of
England. He has at length brought his survey of five years to a
successful termination; and his work will form a most important

Geological Society. 317

step in the progress of geological science, not merely as elucidating
the history of a portion of the sedimentary formations of our island,
but as fixing the characters of a succession of normal groups to
which the strata of other parts of Europe, and perhaps of America,
may be referred. A large and beautifully illustrated treatise, in
which he intends to give a detailed description of his original ob-
servations and views, will soon be published. In the mean time we
have tasted, as it were by anticipation, the fruits of his labours,
having, year after year, received at our meetings the earliest intel-
ligence of his discoveries, and having freely discussed and criticized
them long before it has been possible for him to lay the whole in a
matured and digested form before the public. You are aware that
the system of rocks, which have been the chief object of his re-
search, constitutes the upper part of what was formerly called the
transition or greywacke series. In these strata, which had previ-
ously remained in a state of obscurity and confusion, he has distin-
guished several formations. The old red sandstone rests conform-
ably on the uppermost of these, while the lowest of them repose
both conformably and unconformably on the ancient slate-rocks of
Wales. Mr. Murchison proposes the general name of “ Silurian”
for this whole system, as the strata may best be studied in those
parts of England and Wales once occupied by the ancient British
nation the Silures.

The necessity of a new term has arisen from the uncertain lati-
tude with which the word “transition ” had been applied, some au-
thors including in it the carboniferous rocks, and also from the still
greater confusion introduced by the word “ greywacke,” a term which
can only be employed conveniently, in a mineralogical sense, to
designate a peculiar kind of rock which has been formed at many
successive epochs. Thus, for example, in the memoir now under
review, it is shown that in Pembrokeshire grits, which have passed
for greywacke, occur in the true coal-measures, in the old red sand-
stone, in the Silurian, and in the still older systems of rock.

Below the Silurian strata are slate-rocks of older date, in which
traces of organic remains have been again detected ; and Professor
Sedgwick has suggested the name of Cambrian for this more ancient
system, which is conterminous over a wide territory with the Silu-
rian formations, the relative position of both being clearly seen.

Mr. Murchison has recently traced the Silurian system running in
zones through Pembrokeshire, and there rising out in the coast
cliffs from beneath the old red sandstone as conformably as in the
interior of the country,—an important verification of the accuracy
of his previous determinations. Great lithological changes are, how-
ever, observed to take place in these localities, so distant from the
best types of the system; thus, the “ Ludlow and Wenlock” formations
are no longer distinctly separated by subordinate limestones, and
are therefore simply termed the ‘ upper Silurian rocks,” and these,
changing their soft argillaceous characters of “ mudstone,” become
hard sandstones, yet contain some well-known organic remains ;
whilst the lower Silurian rocks, or Caradoc and Llandeilo formations,
not only maintain their usual fossil distinctions, but exhibit lime-

318 Geological Society.

stones of much greater thickness than in any other part of their
course. Mr. Murchison has also shown that rocks oceupying a large
coast tract in Pembrokeshire, which from their mineral aspect had
been laid down as “greywacke”, consist of true coal-measures.
After noticing a ridge of intrusive rocks in Caermarthenshire, be-
tween the Towey and the Taf, as connected with certain great lines
of dislocation, he points out, in the Cambrian System of Pembroke-
shire, examples of the existence of two classes of trap rock, one
bedded or contemporaneous, the other amorphous and of posterior
intrusion. He further shows that the main directions of the stra-
tified deposits of this county are parallel to divergent zones of
trap.

In another paper the same author states that he has lately disco-
vered to the north-west of Shrewsbury, proofs of an eruption of
trap posterior to the new red sandstone, and probably to the lias.
This line of fissure along which he has observed the new red sand-
stone affected for a distance of thirty miles is on the precise pro-
longation of a linear eruption in the Breiddin Hills, which he had
previously pointed out as having been in progress during and after
the epoch of the deposition of the Silurian strata. The more modern
trap is made up of a peculiar felspathic rock identical with some
of these at the great vent of eruption fifteen miles distant, where
they both alternate with and are intruded into the more ancient
deposits.

It appears from these observations that volcanic operations were
renewed along the same line after a wide interval of time, showing
that we must be on our guard against inferring the synchronism of
coincident lines of derangement. The repetition also in the same
spot and at two distant periods of a trap identical in mineral cha-
racter is curious, and reminds me of an opinion lately mentioned to
me by Mr. Von Buch, that the composition of lava is often deter-
mined by that of preexisting volcanic rocks near the point of erup-
tion. Thus on two opposite sides of the same volcano, as on Tene-
riffe for example, a trachytic flow of lava will issue from a mass of
trachyte, and a basaltic flow from rocks of basalt.

Mr. De la Beche has shown that the trappean rocks are associated
in such a manner with the new red sandstone of part of Devonshire,—
among other places, near Tiverton and Exeter,—as to indicate that the
trap and the sandstone were each in the course of formation at the
same period. Some beds of sand present every appearance of hav-
ing been of volcanic origin, and ejected from a crater, but the sand
became mixed with common detrital matter then in process of de~
position at the bottom of the sea. Numerous angular fragments,
some of them even one or two tons in weight, of quartziferous por-
phyry with a felspathie base, are intermingled with the conglome~
rates of the old red sandstone, and do not resemble any trappean
rocks discovered in place in this district. Mr. De la Beche conjec-
tures with much probability that these fragments were ejected from
volcanic vents, and that they fell upon the sand and pebbles then in
the course of deposition around such vents, and were thus included.
The author has not failed to show that the original features of the

Geological Society. 319

bed of the sea, of the period of eruption alluded to, have been obli-
terated by subsequent denudation; and I may suggest that this cause
has often prevented geologists from recognising the analogy of
trappean phzenomena to those of submarine and insular volcanos
now active *.

In another communication Mr. De la Beche informs us that the
“ Cornish grauwacké,” in which term he here comprises the slates
of that country and their associated sandstones and conglomerates,
contains in some places organic remains. Specimens of these fos-
sils have been presented by him to our museum. He also states
that this greywacke formation, which extends into Somerset and
Devon, is older than Mr. Murchison’s Silurian system, and may be
subdivided into natural sections, coinciding perhaps with some ob-
served by Professor Sedgwick in the Cambrian group. ‘The slates
of Tintagel, long since known to be fossiliferous, belong to the same
age as this greywacke of Cornwall.

A joint paper by Professor Sedgwick and Mr. Williamson Peile
has made us acquainted with the carboniferous limestone flanking
the primary Cumbrian mountains, and with the coal-fields of the
north-west coast of Cumberland. These carboniferous strata rest
unconformably on the primary Cumbrian slates. The carboniferous
series is divided into four groups: Ist, The great scar limestone;
2nd, Alternations of limestone, shale, and coal; 3rd, Millstone
grit; 4th, Great upper coal formation. It appears that the struc-
ture of the carboniferous limestone is nearly the same as that of the
Yorkshire chain so admirably described by Professor Sedgwick in
the first part of our fourth volume just published.

Mr. Griffith, who has for so many years been preparing a geologi-
cal map of Ireland, has described to us the position of some veins of
syenite which traverse the mica-slate and chalk near Fair Head in the
county of Antrim. The syenite is composed of dark green erystal-
lized hornblende and brownish red felspar, with occasional grains of
quartz ; and the chief point of interest consists in the circumstance
that the syenitic veins have the appearance in general of being regu-
lar beds in the mica-slate, being for the most part conformable both
in strike and dip. They are found, however, when more closely
examined and traced for some distance, to deviate from the strati-
fication of the mica-slate, and to have an indented and saw-like edge
at their junction. Similar syenitic veins also penetrate through the
chalk in the neighbouring part of the coast, and near their contact
with the chalk nodules or spheroidal masses of syenite are occa
sionally observed so isolated and surrounded by chalk that had not
the intruding veins clearly proved its posteriority, the syenite might
be mistaken for the older rock, rounded fragments of which had
been imbedded in the calcareous stratum. These phanomena
remind us of the isolated nodules of granite which in Cornwall,
the Valorsine, and other countries, occur in the immediate vicinity
of granite veins.

* (See on this subject Lond. and Edinb. Phil. Mazg., vol. vii. p. 515.]

320 Geological Society.

I have next to call your attention to an able sketch of the geo-
logy of Denmark, which you will find at some length in our Pro-
ceedings, from the pen of an eminent Danish naturalist, Dr. Beck,
of Copenhagen. He describes in Bornholm, besides the granitic and
Silurian rocks, certain strata which appear to agree with our Weal-
den group in mineral character and fossil plants, some of these
being the same as those found in the Hastings sands, although the
shells are marine. In Bornholm this formation is characterized by
containing coal. The most remarkable feature in the geology of
Denmark Proper is the great development of the cretaceous system
above the white chalk with nodular flints. In the island of See-
land the ordinary white chalk is covered with a hard yellowish
limestone containing some fossils of the white chalk and others
peculiar to itself, especially univalves of the genera Trochus, Fusus,
Voluta, Oliva, Cyprzea, and Nautilus. At Faxoe this rock consists
of an aggregate of corals of unknown depth, but certainly more
than forty feet thick. When I myself visited the Faxoe quarries in
1834 in company with Dr. Forchhammer, the rock struck me as
agreeing with the description usually given of the limestone in re-
cent coral reefs. The fossil zoophytes of Faxoe are often cemented
together by white chalk, which may recall to your recollection the
recent chalk which Lieut. Nelson has presented to our museum
from the coral reefs of the Bermudas. This recent substance is
not distinguishable from some of the white marking chalk of En-
gland, and like it is composed of pure carbonate of lime. It is in
fact a white earthy mud, known to be derived from the decomposi-
tion of the softer corallines, such as Eschara, Flustra, and Celle-
pora. These observations support an opinion which has long been
entertained by some geologists that all chalk may be derived from
the decomposition of shells and zoophytes.

While on this subject I may mention a discovery made by Mr.
Lonsdale during the last summer, and which he has permitted me
to announce. In arranging our collection he has found that our
common white chalk, especially the upper portion of it, taken from
different parts of England, (Portsmouth and Brighton among others, )
is full of minute corals, foraminifera, and valves of a small ento<
mostracous animal resembling the Cytherina of Lamarck. From
a pound of chalk he has procured, in some cases, at least a thou-
sand of these fossil bodies. They appear to the eye like white
grains of chalk, but when examined by the lens are seen to be fossils
in a beautiful state of preservation.

According to Dr. Beck there is a whitish and hard chalk above
the Faxoe beds almost entirely made up of pulverized zoophytes
including bivalves and Echini, chiefly of the same species as those of
the white chalk with flints, and with corals like those of Faxoe.
There are layers of flint or chert in this upper division. These
conclusions, drawn from a careful examination of an extensive series
of the Danish fossils, are very important, for it was formerly ima~
gined by Dr. Forchhammer that the Faxoe beds and the overlying
chalk belonged to the calcaire grossier, an idea suggested by the

Geological Society. 321

generic resemblance of the shells to those of the tertiary deposits.
But none of the species, according to Dr. Beck, agree with any
known tertiary fossils, and the secondary genera Ammonite and
Baculite occur among the Faxoe shells. Some of the Faxoe corals
agree with those of Maestricht, and the newest of the cretaceous for-
mations of Seeland and Jutland agree more nearly with those com-
monly called the Maestricht beds than with any previously known.
Dr. Beck, however, says that the organic remains differ on the
whole from those of Maestricht, and are more analogous to those
found at Kinruth near Liege.*

The cliffs of Méen, one of the Danish islands, are composed of white
chalk with nodular flints. The fossils agree with those of the chalk
of England and France, as was shown in the year 1827 by the list
of more than one hundred species of them given by Dr. Beck in
Leonhard’s Taschenbuch der Mineralogie. ‘Two years before, Dr.
Forchhammer had published in the Transactions of the Royal Danish
Academy his opinion respecting Méen, and extracts from his paper
afterwards appeared in the Edinburgh Journal of Science for July
1828. He then considered the Méen chalk to be an integral part
of the same tertiary deposit of sand and clay which contains erratic
blocks in Denmark; and in confirmation of this opinion he gave
sections representing an alternation of chalk with beds of tertiary
sand, clay, and loam. Being desirous of inquiring into this singular
phenomenon I visited the Méen cliffs in company with Dr. Forch-
hammer in 1834, and came to a different conclusion. I have explained
to the Society my reasons for inferring that the association of the
cretaceous and tertiary deposits may be referred to the violent dis-
turbances which the chalk strata have undergone. The cretaceous
beds are curved, vertical, or shifted, and, upon the whole, more de-
ranged than the chalk in Purbeck or the Isle of Wight. In fact
the movements have been on so great a scale that masses of the
overlying clay and sand have subsided bodily into large fissures
and chasms, intersecting the chalk to the depth of several hundred
feet. Some of the intercalations of clay and sand in the midst of
great masses of unconformable chalk can only, I think, be explained
by supposing engulfments of superincumbent matter, such as are
described to occur during earthquakes. These appearances are
analogous to those exhibited by masses of chalk nearly enveloped
in crag near Trimmingham in Norfolk, although the Danish phe-
nomena are on a much grander scale. Dr. Forchhammer did not
fully concur in these opinions in 1834, but he appears to have since
adopted them for the most part, in an excellent memoir on the geo-
logy of Denmark, a copy of which has been lately sent by him to
the Society, accompanied by a small coloured map of the whole of
Denmark and Bornholm.

As the fossils of the upper cretaceous series of Denmark are very
peculiar, and of so much interest from their position, I have plea-
sure in stating that figures and descriptions of them are in the course
of publication by Dr. Beck, and I may add that we owe this work

* On this subject see Lond, and Edinb. Phil. Mag., vol. vii. p. 413, note.)

$22 Geological Society.

to the liberality and the zealous interest taken in our science by an
illustrious member of our Society, the Crown Prince of Denmark,
The collection of recent shells formed by His Royal Highness and
now in his private cabinet,—more extensive perhaps than any other
in Europe,—has afforded Dr. Beck the most ample facilities of com-
paring fossil and recent shells, and from the opportunities thus en-
joyed we may look, at no distant period, for results which will ma-
terially advance the general progress of fossil conchology.*

Few communications have excited more interest in the Society
than the letters on South America addressed by Mr. Charles Darwin
to Professor Henslow. Mr. Darwin has devoted four years, from
1832 to 1835 inclusive, to the investigation of the natural history
and geology of South America. From the position of the tertiary
deposits which exist on both sides of the southern Andes, he con-
cludes that. the primary chain must have had a great elevation an-
terior to the tertiary period. A transverse section from Rio Santa
Cruz to the base of the Cordilleras, and another on the Rio Negro
exhibit the structure of what Mr. Darwin calls the great southern
tertiary formations of Patagonia, which may be separated into groups
of distinct periods analogous to those already established in Europe,
The lowest group is of great extent and thickness, and in one in-
stance was observed to alternate with a bed of ancient lava, which
seemed to mark the commencement of the eruptions from the cra-
ters of the principal chain of the Andes. Among the shells and
corals, even of this lowest deposit, are some which are supposed to
belong to species now living in the neighbouring Pacific. Over-
lying this is a stratum of rolled porphyry pebbles, which the author
traced for 700 miles. Scattered over the whole, and at various
heights above the sea, from 1300 feet downwards, are recent shells
of littoral species of the neighbouring coast, so that every part
of the surface seems once to have been a shore, and Mr. Darwin
supposes that an upheaval to the amount of 1300 feet has been
owing to a succession of small elevations, like those experienced in
modern times in Chili.

The principal section described is one transverse to the Andes,
extending from Valparaiso to Mendoza. The Cordillera consists
here of two separate and parallel chains, the western being com-
posed of stratified sedimentary rocks resting on granite. The
strata are violently dislocated and contorted along parallel north
and south lines, and become crystalline as they approach the gra-

* Having been led to speak of cretaceous fossils, I may state that it has
been a question whether certain fossils found in the English chalk, and
called by Mr. Mantell Hippurites Mortoni, are truly referrible to the genus
Hippurite. When I first saw one of these fossils in the collection of Mr.
Robert Hudson, I conjectured that it might belong to the family of Conia
and Balanus ; but I regret that this opinion has been published as mine in
Loudon’s Magazine, as it was abandoned by me as soon as I had opportu-
nities of minutely examining the specimens. (See Loudon’s Mag., No. 58.)
Without being able to decide whether they are truly Hippurites, I may
state that I believe them to belong to the family of Rudistes of Lamarck,
and that they are not allied to Conia.

Geological Society. 323

nite. Some of the slates and limestones, probably referable to the
transition period, contain organic remains at an elevation of 13,000
feet above the sea. In the eastern chain are sandstones and conglo-
merates, and associated felspathic rocks regularly bedded, and more
recent than the rocks of the western chain, being partly made up of
their debris. After much investigation Mr. Darwin convinced him-
self that these were of the same age with certain tertiary deposits of
Patagonia, Chiloe, and Conception, resembling them in mineral cha=
racter and in the lignite and fossil wood which they contain. In
one escarpment is seen a sandstone of this system in which there
is a wood of petrified trees in a vertical position, some of the trees
being perfectly silicified and of dicotyledonous wood, others con-
‘sisting of snow-white columns. of coarsely crystallized carbonate of
lime. They appear to have formed a clump of trees which had
grown on lava and was then submerged, so that layers of fine sand
stone were quietly deposited between the trunks. The enveloping
sandstone rests on lava, and is again covered by a bed of black au-
gitic lava about 1000 feet thick. Over this there are at least five
other grand alternations of similar rocks and aqueous deposits,
amounting in thickness to several thousand feet. The same sedi-
mentary strata, or the continuation of them, are not only altered by
granite, but are traversed by dikes of granite proceeding from the
mass, and also by numerous metallic veins of iron, copper, arsenic,
silver, and gold, all of which can be traced to the underlying gra-
nite. A gold mine has been worked close to the clump of silicified
trees.

From these observations I am led to suspect that, as in some parts
of the Alps, the metamorphic structure has been assumed by strata
high up in the secondary series, so in the Andes the same structure
has been superinduced on certain tertiary deposits which have been
also penetrated by granitic and by metalliferous veins.

Dr. Daubeny has analysed a new thermal spring discovered near
the town of Torre del Annunziata in the Bay of Naples, and he re-
fers the origin of nitrogen gas in this and other springs in the vol-
canic region of Naples and Mount Vultur to a process of subterra-
nean oxygenation analogous to combustion. In the excavations
made in voleanic tuff and lava near Torre del Annunziata for gain-
ing access to the spring, vestiges of walls and buildings with fresco
paintings, and other traces of human art were discovered, and vege=
table mould containing the stems of reeds, similar to those now
growing in the neighbourhood, and a fir and cypress tree in an up-
right position. The buildings must have been overwhelmed before
the soil existed on which the fir and the cypress grew, as this soil
was formed upon the materials which enveloped the town.

Mr.H. E. Strickland and Mr. Hamilton have examined a cavity be-
low the level of the sea in Cephalonia adjoining the coast, into which
a constant stream of sea water is flowing, and has been flowing for
years. This singular phenomenon had previously attracted the at-
tention of Mr. Martin and of Lord Nugent and others, some of
whom had speculated, like Mr. Strickland, on the probability of the

$24 Geological Society.

water thus descending through crevices being converted into va-
pour in subterranean hollows, and then carried off in other direc-
tions in the form of stufas or hot springs. I forbear to enlarge on this
subject at present, as a description of the facts drawn up by Mr. Mar-
tin before Mr. Strickland’s visit, will shortly be read to the Society.

We have received from Capt. Belcher a suite of geological spe-
cimens from various parts of the west coast of Africa, with remarks
on the reefs and sand-banks of that coast; and a collection from the
Rev. W. Hennah of recent calcareous limestone and volcanic pro-
ducts from the island of Ascension.

I shall next consider some papers relating more or less exclusively
to fossil zoology, which have been read at our meetings during the
last session. We are indebted to Mr. Broderip for a description of
some new species of fossil Crustacea and Echinodermata, which were
discovered by Lord Cole and Sir P. Egerton in the lias of Lyme
Regis. One of these crustaceans belongs to a genus intermediate
between the Palinurus and the Shrimp. It is of a gigantic size
compared to any recent species, and belongs to a division of which
the living types have been only met with in the arctic regions.

Sir P. Egerton has described some peculiarities of structure in
the occipital bone of an Ichthyosaurus, observed in the skeleton of
a new and gigantic species recently discovered by Miss Anning at
Lyme Regis. He also states that the axis and atlas in this genus
are usually found adhering firmly together, and they are connected
by an auxiliary bone, showing that strength rather than freedom of
lateral motion was required in the neck of these animals. These
observations have been confirmed by Mr. Owen and Mr. Clift.

It has often been a question whether the bones of birds had ever
occurred in strata below the chalk, some of the thin fragile bones
found at Stonesfield, and formerly considered to be those of birds,
having been ascertained to belong to Pterodactyls. In order to
elucidate this point, Mr. Mantell lately placed all his specimens from
the Wealden, supposed to be those of certain Grallz, or waders, in
the hands of Mr. Owen, and the result of his examination has con-
firmed Cuvier’s opinion that they are true ornitholites. They seem,
therefore, to be the oldest authenticated fossils of this class hitherto
found in Great Britain. The rarity of such remains in geological
formations, especially in the marine, cannot surprise us; for in the
recent shell marl of Scotland, formed in lakes much frequented by
water-fowl up to the moment of their drainage, no bones of birds
have as yet been detected amongst the numerous relics of deer, ox,
pig, and other quadrupeds occurring in the marl.

Mr. Darwin, in his travels in South America before alluded to,
found, in crossing the continent from the Rio Negro to Buenos
Ayres, many large bones of Mastodons, and other remains of the
Mastodon at Port St. Julian, 50° S, lat., at a distance of more
than six hundred miles from the former. He also saw, in the
gravel of Patagonia, many bones of the Megatherium, and among
the remains of five or six species of quadrupeds associated with them,
he detected those of a species of Agouti.

Geological Society. 325

Our museum has just been enriched by a truly magnificent present
of fossil bones from India, more valuable than any which have reached
England since those obtained by Mr. Crawfurd and Dr. Wallich from
Ava. They were collected and presented to us bya gentleman whom we
last year elected a Fellow of this Society, Capt. Cautley of the Bengal
Artillery, and their existence seems to have been first distinctly recog-
nised by Dr. Falconer, superintendent of the Botanic Garden at Saha-
runpore. These organic remains come from the range of hills for-
merly called Sewalik, which skirt the base of the Himalayan mountains
from the Ganges to the Sutluj rivers, or from north lat. 30° to 31°.
They abound in part of the range to the westward of the Jumna river,
and belong to the genera Mastodon, Elephant, Hippopotamus, Rhi-
noceros, Hog, Anthracotherium, Horse, Ox, Deer, Antelope, Ca-
nis, Felis, Gavial, Crocodile, Emys, Trionyx, besides fish and shells.
Among the fossils there are some considered to be new genera, and
one which Messrs. Cautley and Falconer have called Sevatherium.

We have also received a splendid collection of specimens of rocks
from the Himalayas, illustrating the two sections published by Mr.
Royle in his work on these mountains, from the plains to the snowy
passes, and his section across the central range of India.

Several new facts have been brought to light in fossil ichthyo-
logy during the last year. Sir P. Egerton has found in the coal-
field of North Staffordshire, among other remains of fish, some
scales of the Megalichthys, that large sauroidal fish first described
by Dr. Hibbert as occurring at Burdiehouse, near -Edinburgh. I
have lately seen a large tooth of this fish in a mass of Cannel coal
found in Fifeshire by Mr. Horner and described by him in a paper
read before the Royal Society of Edinburgh. It will be remem-
bered that these teeth were formerly referred to saurians, to which,
in fact, the Megalichthys had a much nearer affinity, according to
Mr. Agassiz, than has any fish now living. Sir P. Egerton has also
published a catalogue of the fossil fish in his cabinet at Oulton Park,
and in that of Lord Cole, at Florence Court; two collections which
are described by Mr. Agassiz as unrivalled in England in this de-
partment of organic remains, and only equalled by two others in
the rest of Europe, that of Count Munster, at Baireuth in Bavaria,
and that of the Royal Museum of Paris*. In this catalogue Sir
Philip has given the names and loealities of about 200 ichthyolites,
British and foreign, and has indicated the geological position of
each.

Remains of fishes have been found by Mr. Prestwich in a formae
tion of sandstone and red conglomerate which overlies the old red
sandstone in Banffshire. He supposes the deposit to be of the age
of the coal-measures, an opinion which is in accordance with the
characters of the ichthyolites as determined by Mr. Agassiz.

One of the most perplexing enigmas in paleontology has lately
been solved by Dr. Buckland, who has discovered that some cu-
rious fossils of the oolitic and cretaceous strata, which had long

* Agassiz, Poiss. [oss., 4me livr. p. 45.

326 Geological Society.

baffled the skill of comparative anatomists, are in fact the upper
and lower jaws of extinct species of Chimera, a rare genus of
living fish. These fossils had been found by Sir P. Egerton in the
Kimmeridge clay, by Mr. Townsend in the Portland stone, and by
Mr. Mantell in the chalk. They belong to four distinct species,
of which the characters are given by Mr. Agassiz. The scientific
world is indebted to the splendid museum of comparative ana-
tomy at Leyden for the opportunities enjoyed by Dr. Buckland
of comparing the skeleton of the recent Chimera with the fossils
alluded to.

Mr. Agassiz has described two very singular genera of fossil fish
from the lias, one of which has been known under the name of
Squalo-raia from Lyme Regis; the other from Whitby, called Gy-
rostris mirabilis, probably the largest known fish.

Hitherto the new red sandstone in Great Britain had been desti-
tute of all organic remains, but some distinct impressions of fish of
the genus Paleoniscus, 4g., have now been observed in this for-
mation near Dungannon in Ireland. The geological position of these
has been pointed out by Mr. Murchison, and a slab of sandstone
presented to the Society by Mr. Greer exhibits on a single surface
only two feet square, impressions of about 250 fishes.

I have already had occasion to allude more than once to the
name of Agassiz, on whom the Council have this day conferred the
Wollaston Medal. I may say with pleasure, that in his second
visit to England, as in that of the preceding year, he has given an
impulse to the study of fossil remains in various departments which
will long be felt in this country. It is not merely sound knowledge
which he has freely communicated to all who have enjoyed his so-
ciety, but what is even of more lasting profit, a generous enthusiasm
for the study of every department of natural history and particularly
of fossils. The great work on which he is now engaged yields not
in importance to any that has ever been undertaken for the illustra-
tion of organic remains, and the progress which he has already made
at so early an age, holds out the most encouraging prospects of his
future success.

When we consider the strong ties of affinity which unite together
all animals of the vertebrate classes, and reflect that man himself,
viewed in reference to his organization, belongs to this great divi-
sion of the animal kingdom, we cannot but feel the highest interest
in tracing the remains of the vertebrate animals through geological
formations of every age, from the newest to the most ancient. Ina
small part of Europe alone more than 800 species of ichthyolites
have already been determined. They are distributed through strata
of all epochs; no less than 54 species have already been discovered
in the carboniferous rocks, and five or six have been met with in
the still older Silurian formations.

The museums of Great Britain alone have afforded to Mr. Agassiz
no less than 300 new species of ichthyolites, 50 of which have been
added since our last anniversary. He had previously pointed out
as a general law that particular generic types are strictly confined

Geological Society. 327

to certain groups of strata, and it is remarkable that so vast an
accession of new species offers but few exceptions to the rule.
In the chalk two species have come to light belonging to genera
before observed in the oolitic series only, and a distinct species of
one of these genera extends even into the lower or Eocene tertiary
deposits.

The labours of Mr. Charlesworth have thrown much light on the
structure of the crag of Suffolk and Essex, and on the fossils of
that deposit. He proposes to divide the crag into the upper or red
crag, and the lower or coralline crag, the last of which consists for
the most part of calcareous sand, derived chiefly from the decom-
position of zoophytes and shells, and in which many very perfect
corals and testacea are preserved. Among other places this coral-
line crag may be well examined at Tattingstone, Ramsholt, Orford,
and Aldborough. It is now many years since Mr. Wood, of Hes-
kerton in Suffolk, formed a large collection of crag fossils, amount-
ing in number to no less than 450 species of the classes Annulata,
Cirrhipeda, Conchifera, and Mollusca. Out of 370 species of shells
found in the lower crag, Mr. Wood identifies 150 with those found
in the red crag. Of these 150 species, common to the two deposits,
Mr. Charlesworth suggests that many may have belonged to the
lower bed and have been washed into the newer one, in the same
manner as some fossil shells of the chalk have been evidently im-
bedded in the crag*.

Such accidental mixtures have doubtless occurred, and they have
been occasionally remarked by geologists in other places under
analogous circumstances. But I continue to believe that these
upper and lower divisions of the crag should be referred to the
same geological period. The determination of that period or the
exact place which the crag should occupy in the chronological series
of European strata is a more difficult question. When I first sub-
mitted 111 species of crag shells to the examination of M. Deshayes,
he was of opinion that 66 of them were extinct, and that the others
belonged to recent species now inhabitants of the Germian Ocean.
I lately laid before him 60 species from the coralline crag with which
Mr. Charlesworth had favoured me, and he was still of opinion that
the proportion of recent species was equally great.

But I should add that the suites of individuals of each species
were not so full and complete as might have been desired, to enable
these identifications to be placed beyond all doubt. Dr. Beck
has lately seen 260 species of crag shells in Mr. Charlesworth’s ca-
binet in London, and informs me, that although a large proportion of
the species approach very near to others which now live in our nor-
thern seas, he regards them as almost all of distinct species,.and un-
known as living. Both he and M. Deshayes have declared the
shells to be those of a northern climate, and according to Dr. Beck
the climate may even have resembled that of our arctic regions.

* [See Mr. Charlesworth’s paper on the Crag, in L. and E. Phil, Mag.
vol. vii. p. 81; also p, 413, note, and p, 464 of the same volume. ]

328 Geological Society.

In regard to the discordance in the results at which these eminent
conchologists have arrived, it may arise not only from the unequal:
opportunities which they have enjoyed of examining the necessary
data, but also, in part, to the different estimate which they have
formed of the amount of variation necessary to constitute a distinct
species. One example will sufficiently illustrate my meaning. Those
naturalists who agree with M. Deshayes in referring all the living
varieties of Lucina divaricata brought from different countries to
one and the same species, will identify many more fossils with re-
cent shells than those who agree with Dr. Beck in dividing the
same recent individuals of Lucina divaricata into six or eight di-
stinct species. Provided, however, each zoologist is consistent
with himself, and provided the distinctive characters relied on as
specific by each are commensurate one with another, no confusion
will arise.

In reviewing the proceedings of the Society during the last year,
I find that the remaining memoirs, numerous as they are, may be
all referred to one great class of subjects, for they either relate to
changes now going on upon the surface of the earth as attested by
man, or to geological proofs of similar changes since the rivers, lakes,
and seas were inhabited by the existing species of testacea. Under
these heads I shall be led to consider the effects of modern earth-
quakes in upheaving and depressing the land; the gradual rising of
land in one region and the lowering of its level in another; the rolling
in of great waves of the sea upon the coast during earthquakes ; the
transportation of rocks by floating ice; the signs of upraised beaches
containing marine shells ; erratic blocks ; alluvial deposits of different
ages; and other kindred topics on which a variety of new facts have
been collected.

The last year has been signalized in South America by one of
those terrific convulsions which have so often desolated the western
coast since the discovery of the new world. A brief notice of this
catastrophe was sent me by Mr. Alison, written immediately after
the event. He mentions that on the 20th of February, 1835, when
Conception, Chillan, and other towns were thrown down in ruins,
the sea first retired from the shores of the Bay of Conception, and
then returning in a wave about twenty feet high, rolled over several
of the towns, and completely destroyed whatever the earthquake
had left uninjured. He also states that the coast of the bay was
reported to have been heaved up, and that a rock off the landing~
place at the port of Taleahuano, which before the shock was nearly
level with high water, stood afterwards three feet above that mark.
Large fissures were made in the earth, and water burst from some
of them.

In these and other particulars Mr. Alison’s letter agrees with
the more circumstantial account sent to the Royal Society by
Mr. Caldcleugh, who was resident at Valparaiso, but who drew his
information in great part from eye-witnesses. He mentions that a
great number of the volcanos of the Chilian Andes were in a state
of unusual activity during the shocks, and for some time preceding

Geological Society. 329

and after the convulsion. Among others, Osorno, of which the
cone rises 3900 feet above the sea, and which is situated on the
mainland north-east of the island of Chiloe was in eruption, lava
being seen to flow from its crater. Several others are also noticed,
and the lava emitted from one of them is stated to have covered
an area eight leagues in circumference and to the depth of 33 yards.
The ashes reached to the distance of 300 leagues. I refer you to
these statements because it is rare to meet with any recent descrip-
tions of the emission of lava and ashes from the high cones of the
Andes.

The same writer was informed that the strata of clay-slate, form-
ing the shore of the Bay of Conception, were elevated from three to
four feet, whereas the rise at San Vicente, south of Talcahuano,
amounted to only 15 feet. Mr. Caldcleugh was also informed that
the island of Santa Maria, in the Bay of Conception, was upheaved
about eight feet.

At the same time the island of Juan Fernandez, distant 360 miles
from Chili, was violently shaken and devastated by a great wave.
A dense column of vapour issued from the sea about a mile from
the coast, and flames were seen at the same spot in the night which
illumined the whole island. At this point in the sea whence the
flames were emitted the depth of water was afterwards ascertained
to be no less than 69 fathoms.

At a court-martial, lately held at Portsmouth, in consequence of
the wreck of the Challenger frigate on the coast of Chili, m May
1835, some notes of Capt. FitzRoy were read, and afterwards com-
municated by Capt. Beaufort to the Society, in which he describes
some remarkable alterations produced by the earthquake of February
in the direction of the currents on the Chilian coast. A more de-
tailed account of the convulsion has just been received at the Ad-
miralty from the same officer, with a sight of which I have been
favoured, but no allusion is here made to the currents. ‘There are,
however, other facts perfectly new and of the highest importance at-
tested in this memoir, and as they come from an observer of great
experience in hydrographical surveying, who examined the Bay of
Conception immediately after the shocks, they will remove all doubts _
from the minds of those who have questioned the power of earth-
quakes to cause the permanent upheaval of land.

Capt. FitzRoy states, that on the 20th of February, 1835, the
earthquake was felt at all places between Copiapo and Chiloe from
north to south, and from Mendoza to Juan Fernandez from east
to west. Conception and other towns were thrown down. After
the shock the sea retired; the vessels in the bay grounded, even
those which had been lying in seven fathoms water ; all the shoals
in the bay were visible; and soon afterwards a wave rushed in and.
then retreated, and was followed by two other waves. The verti-
cal height of these waves does not appear to have been greater
than from 16 to 20 feet, although they rose to much greater heights
when they rushed upona sloping beach. During the shocks the
earth opened and closed rapidly in numerous places, The direction

Third Series, Vol, 8. No. 47. April 1836, 2L

330 Geological Society.

of the cracks was not uniform, though generally from south-east to
north-west. The earth was not quiet during three days after the
great shock, and more than three hundred shocks were counted
between 20th February and 4th of March. The loose earth of the
valley of the Bio Bio was everywhere parted from the solid rocks
which bound the plain, being separated by cracks from an inch to
a foot in width.

In the Bay of Conception two explosions or eruptions were seen
in the sea while the great waves were coming in. One beyond the
island of Quiriquina appeared to be a dark column of smoke in
shape like a tower; another rose in the Bay of San Vicente like
the blowing of an immense imaginary whale. Its disappearance
was followed by a whirlpool which lasted some minutes. It was
hollow and tended to a point in the middle, as if the sea was pouring
into a cavity of the earth. The water in the bay appeared to be
everywhere boiling, bubbles of air or gas were rapidly escaping,
and dead fish were thrown ashore in quantities.

For some days after the 20th February the sea at Talcahuano did
not rise to the usual marks by four or five feet vertically. ‘ Some
thought that the land had been elevated, but the common and pre-
vailing opinion was that the sea had retired. This difference gra-
dually diminished till, in the middle of April, there was only a dif-
ference of two feet between the existing and former high-water
marks. The proof that the land had been raised exists in the fact that
the island of Santa Maria was upheaved nine feet; but of this pre-
sently. When walking on the shore, even:at high-water, beds of dead
mussels, numerous chitons and limpets, and withered sea-weed still
adhering, though lifeless, to the rocks on which they had lived, every=
where met the eye—the effects of the upheaval of the land.”

From the above extracts, then, it appears that in the opinion of
Capt. FitzRoy some of the land was first raised in February four or
five feet, and that it afterwards gradually returned towards its for-
mer level, so that in about two months the temporary increase of
its height was diminished by more than one half.

The observations which follow respecting Santa Maria, an island
seven miles long and two broad, in the Bay of Conception, deserve
particular attention, and I shall give them in Capt. FitzRoy’s own
words ; for although in so doing I anticipate a communication which
I trust will hereafter be given in full to the Society*, I am only sup-
plying the proofs of the elevation which was asserted as a fact in
Capt. FitzRoy’s notes read before you during the last year.

“It appeared that the southern extreme of the island had
been raised eight feet, the middle nine, and the northern end up-
wards of ten feet. The Beagle visited this island twice, at the end
of March and in the beginning of April. At her first visit it was
concluded, from the visible evidence of dead shell-fish, water-marks,
and soundings, and from the verbal testimony of the inhabitants,

* Since the above was written the whole memoir has appeared in the
Nautical Magazine for March 1836.

Geological Society. 331

‘that the land had been raised about eight feet. However, on re-
turning to Conception, doubts were raised, and to settle the matter
beyond dispute, or the possibility of mistake, the owner of the
island, Mr. Salvador Palma, accompanied us. An intelligent Ha-
noverian, who had lived two years there and knew its shores tho-
roughly, was also a passenger in the Beagle. His occupation upon
the island was sealing. When we landed, the Hanoverian, whose
name was Antonio Vogelborg, showed me a spot from which he used
formerly to gather Choros by diving for them at low water. At
dead low water, standing upon that bed of choros, and holding his
hands up above his head, he could not reach the surface of the
water. His height is six feet; on that spot when I was there the
choros were barely covered at high spring tide.

* Riding round the island afterwards with Mr. Palma and Vogel-
borg, many measures were taken in places where no mistake could
be made. On large steep-sided rocks, where vertical measures
could be correctly taken, beds of dead mussels were found ten feet
above the present high-water mark. A few inches only above
what was taken as spring-tide high-water mark were putrid shell-
fish and sea-weed, which evidently had not been wetted since the
upheaval of the land. One foot lower than the highest bed of mus
sels, a few limpets and chitons were adhering to the rock where
they had grown. Two feet lower than the same, mussels, chitons,
and limpets were abundant.

* An extensive rocky flat lies around the northern parts of Santa
Maria. Before the earthquake this flat was covered by the sea,
some projecting rocks only showing themselves. Now the whole
flat is exposed. Square acres (or many quadras) of this rocky flat
were covered with dead shell-fish, and the stench arising from them
was abominable. By this elevation of the land the southern port
of Santa Maria has been almost destroyed ; there remains but little
shelter, and very bad landing. The soundings have diminished a
fathom and a half everywhere around the island.”

The author then goes on to inform us that at Tubul, to the south-
east of Santa Maria, the land has been raised six feet. At Mocha
two feet. No elevation has been ascertained at Valdivia, north-
ward of Conception; at Maule, according to the assertion of the
governor, the chief pilot, and other residents, the land instead of
being elevated had sunk two feet, for they said there were two feet
more water on the bar after the shock, and the banks of the river
were lowered. Capt. FitzRoy, however, suggests that a rush of wa~
ter might have shifted the loose sands of the bar; so that he doubts
the subsidence at Maule, and only feels certain that the land had
not risen there.

It is scarcely necessary for me to advert to the striking analogy
of the phenomena observed by Capt. FitzRoy and those which were
formerly described by Mrs. Maria Graham (now Caleott), and pub-
lished in our Transactions, respecting the Chilian earthquake of 1822.
The coast of Valparaiso, Quintero, and other places was then stated
to have undergone unequal erat the greatest amounting only

9 9

wo

332 Geological Society.

to a few feet, and banks of sea-shells were laid dry above high-water
mark. But these statements, given on the authority of Mrs. Gra-
ham’s personal observation, and confirmed by others to which I shall
presently allude, have been met by a direct counter-statement so
circumstantial and explicit as to deserve the fullest consideration.
Mr. Cuming, well known to you by his numerous researches in
conchology, declares that being at Valparaiso before and during the
earthquake of 1822, and residing there constantly until 1827, he
could never detect any proofs of the rise of the land, although his
pursuit of conchology and natural history in general caused him to
visit frequently the rocks and inlets with which the northern and
southern parts of the bay abound. These rocks were covered with
Fuci, Patella, Chitons, Balani, &c., yet he never perceived the least
difference in their appearance from the date of his arrival to his
finally quitting Valparaiso, nor observed any trace of them except
in situations covered by the tide. He also remarked that the wa-
ter at spring tides rose after the earthquake to the same point on a
wall near his house which it had reached before the shocks. He
imagines that the idea that a change had taken place in the relative
level of land and sea originated in the gain of land opposite Valpa-
Taiso, occasioned by the accumulation of detritus at points where
the tide had flowed previously to the earthquake. Mr. Cuming
first heard of the notion of the land having been elevated at Valpa-
raiso when Mrs. Graham’s paper read to the Geological Society in
1824 was talked of at Valparaiso. Neither he nor his friends
were then able to subscribe to the opinion expressed in that com-
munication.

On the other hand, Lieut. Freyer, R.N., in a letter read to you
during the last session, observes, that being at Valparaiso after the
earthquake of 1822, he saw a shelly beach to the east of the town,
above the reach of the tides; and rocks, which was pointed out to him
as being less under water than it had been before the convulsion.
Dr. Meyen also, a Prussian traveller, who visited Valparaiso in 1831,
says he examined the coast there and found appearances in corro-
boration of Mrs. Graham’s statements. I may also repeat what I
have elsewhere recorded, that some years after the event I applied
to Mr. Cruckshanks, an English botanist, who resided in Chili at the
time of the earthquake, whether he had seen any signs of the alleged
change of level. He said that he examined the coast at Quintero
after the shocks, and satisfied himself that it had been uplifted seve=
ral feet, and that the fishermen told him that the ocean had gone
down and was lower than before, in confirmation of which they
pointed to some rocks of greenstone at Quintero, a few hundred
yards from the beach, which were always under water previously
to the great shock of 1822, but were afterwards uncovered when
the tide was at half ebb.

Without pretending that I can reconcile this contradictory evi-
dence, I may suggest that some discordance in the accounts may
have arisen from a want of uniformity in the movement at different
places, and still more from a subsequent sinking down of some

Geological Society. 333

of the land which was first raised, in the manner described by Capt.
FitzRoy as having taken place near Talcahuano in the spring of last
year. In perusing Mr. Cuming’s account we must all feel that the
author has had no object in view but that of establishing the truth;
and the doubts which he has raised will call for a reinvestigation of
the phenomena; but after hearing all objections, even before the
late convulsion of 1835, I expressed myself satisfied with the proofs
in favour of the elevation of 1822*. If I had still cherished any
scepticism, it would now be removed by the coincidence of the facts
related by Capt. FitzRoy. To suppose that a set of imaginary
phenomena, which appeared at first sight very improbable, and
which no geologist could explain, should have been invented, in
Chili, in 1822, by several intelligent observers, and that thirteen
years afterwards nature should realize, in the same country, the
same phenomena, or others strictly analogous, so as to lend coun-
tenance to all the previous misconceptions, is to imagine a combi-
nation of circumstances almost as marvellous as the upheaval of a
continent itself.

We are indebted to Mr. Woodbine Parish for a collection of histo-
rical notices respecting the effects of the earthquake waves of the
Pacific, which have repeatedly caused great inundations on the coast
of Chili and Peru. The earliest date to which he has traced back
these memorials is the year 1582. The sea usually retired in the
first instance, and then rolled in upon the land, carrying ships far
inland and levelling towns to the ground. Such floods must have
left great banks of sand and gravel, mingled occasionally with bro-
ken and entire shells, upon dry land, considerably above the level
of the highest tides, but they will by no means account for the very
elevated position of recent marine shells on various parts of the
maritime country of Patagonia, Chili, and Perut.

Mr. Freyer, to whom I have before alluded, states that he ob-
served in many parts of Peru, especially near Arica and in the Isle
of San Lorenzo, in the Bay of Callao, lines of shingle and sand, with
shells of existing species, at various elevations above the level of the
sea. The rocks of sandstone and gypsum south of the bold pro-
montory called the Morro of Arica are shaped into distinct terraces
towards the shore, and on these terraces the rock, wherever it is ex-
posed, is seen to be incrusted with balani and millepores. At the
height of about twenty or thirty feet above the sea, these shells and
zoophytes are as abundant and almost as perfect as on the shore;
at upwards of fifty feet they still occur, but in an injured state, for
although there is no rain in this district to hasten their decay, by
alternate moisture and desiccation, still they are abraded by the
sand which is constantly blown over them. Some of the recent
shells occurring at considerable heights in the island of San Lo-
renzo retain their colour almost as freshly as those living in the
adjacent sea. Mr. Darwin has also observed in different parts of
Patagonia and Chili beds of recent shells at various heights above

* Principles of Geology, 4th edit. vol. ii. p. 331.
+ [See Mr. Woodbine Parish’s paper in our last Number.]

334 Geological Society.

the sea, and among them mussels which retained their blue colour,
and emit a strong animal odour when thrown into the fire.

I shall now turn from the modern changes observed in South
America to the evidences of recent alterations in the level of the
land in high latitudes in the northern hemisphere. Dr. Pingel, a
Danish mineralogist and naturalist, has communicated some facts
showing the gradual sinking of part of the west coast of Greenland,
It is now more than fifty years since Arctander inferred that this
coast had subsided, having noticed some buildings in the Firth
called Igalliko, on a low rocky island near the shore, almost en-
tirely submerged at spring tides. From this point, which is in lat.
60° 43! north, to Disco bay, extending to nearly the 69th degree of
north latitude, Dr. Pingel has traced various signs of the depression
of the land, ancient settlements of the Greenlanders and Moravians
being now overflowed by the sea. In one case the Moravians were
obliged to move inland the poles upon which their large boats were
set, and the old poles still remain beneath the water as silent wit-
nesses of the change. It is also mentioned that no aboriginal Green-
lander builds his hut near the water’s edge. Having conversed with
Dr. Pingel, at Copenhagen, on this subject, I am convinced that the
phenomena cannot be explained away by reference to a rise of the
tides at particular points, the advance of the sea being general for
more than 600 miles from north to south, and caused not by the
undermining of cliffs and the denudation of land, but by submers
gence of what was before above water.

I am the less inclined to question the probability of a general sub-
sidence of the land in Greenland, because I now believe that an
equally slow and gradual movement is taking place, but in an oppo-
site direction, throughout a large part of Sweden and Finland. I
ventured formerly to controvert the proofs adduced in favour of
such an upheaval of land in those countries, although the fact had
been advocated by Celsius, the Swede, and in later times by Play-
fair and Von Buch. But after visiting, in 1834, several parts both
of the eastern and western coasts of Sweden, I became satisfied that
an elevation is in progress, more rapid at Stockholm than further to
the south, and greater at Gefle than at Stockholm. The rate of
rise appears in some places to have amounted only to a few inches
in a century, in other places to several feet, but as far as I could
learn from the report of pilots, travellers, fishermen, and traders,
the alteration extends to the North Cape, and is probably felt over
a space more than 1000 miles in length from north to south, and
several hundred miles in breadth. The evidence is derived from
many sources, partly from tradition and from the recollection of
the oldest inhabitants and seafaring men, partly from the position
of ancient buildings on the coast, and partly from marks chiselled
at different periods on rocks bordering the sea, for the express
purpose of indicating the ancient standard level of the waters. As
the details of my own observations have been published in the
Philosophical Transactions of last year*, I need only add that at one

* [See Lond. and Edinb. Phil. Mag., vol. vi. p. 297.]

Geological Society. 385

spot to the south of Stockholm I saw what appeared to me a con=
elusive proof of an alternate rising and sinking of the same land since
this region was inhabited by man, first a depression of the ground
of at least 50 feet below its former level, and then a re-elevation of
the same amounting to at least 50 feet.

The probable cause of the prolonged and insensible movements
of large masses of land opens a wide and inviting field for specu
lation. As we know that volcanic action is never dormant in some
parts of the interior of the globe, it seems most natural to imagine
that an alternate expansion and contraction of the earth’s crust may
arise from a gradual increase or diminution of its temperature.
Mr. Babbage has suggested that as many common kinds of stone
have been shown by experiment to augment in volume when heated,
and decrease in bulk when slowly cooled, a great thickness of sub-
jacent rock may cause the surface to rise or sink according to the
variations experienced in the subterranean temperature. We have
also to consider the effects which might result from the slow cool-
ing and crystallization of large reservoirs of melted matter, on
which subject we have unfortunately as yet few experiments to
guide our conjectures. We know not, for example, whether the
passage from a fluid to a solid state would uplift or let down an
incumbent mass of rock. A dense fluid, subjected to immense
pressure, may, perhaps, on crystallizing into a rock like granite, oc~
cupy more space in its state of solidiry. Imeed not remind you
that as ice floats in water, soa bar of cast iron floats on the surface
of melted iron.

But however obscure the origin of the movements in question,
their reality if admitted affords a key to the interpretation of a va-
riety of geological appearances, some of which I shall now proceed
to consider.

Dr. Beck has mentioned that the oldest strata in Denmark are
often covered by deposits of gravel, sand, and loam, several hun-
dred feet thick, in which, but more commonly upon them, lie erratic
blocks. The sand and gravel beds rarely contain any fossils, but
when shells do occur they are absolutely identical with living species.
He has also found, in the lower valleys of Jutland, more than se-
venty species of shells now living in the German Ocean. These
facts agree precisely with others which I observed in different parts
of Sweden, and which J have described in the memoir before al-
luded to. On the west coast, between Uddevalla and Gothenborg,
the beds of sand, gravel, and clay, containing recent oceanic shells,
are seen at various heights from 100 to 300 feet above the sea.
M. Alex. Brongniart formerly pointed out those which rest on the
gneiss, near Uddevalla, and like him I saw Balani still attached to
the rocks at the height of more than 150 feet above the sea-level.
I ought, however, to state that at the points where I discovered
them they had not been exposed to decomposition in the atmosphere
ever since their emergence. On the contrary, the adhering shells
had been protected by a covering of shelly sand only removed of
late years for road-making. I need scarcely insist upon the obvious

336 Geological Society.

inference that the Balaniand corallines which also cover the rocks, and
which are of the same species as those found on the shells of the re-
cent strata in contact with the rocks, prove that the gneiss was long
submerged beneath the waters, and that the shells werenot washed up
by an inroad of the sea upon the land. In theisland of Orust, opposite
Uddevalla, I found similar appearances, and on other parts of the
western coast ; but on the eastern shores of Sweden or those bor-
dering the Baltic, both to the north and south of Stockholm, a
marked distinction is recognised. In the assemblage of fossil shells
which there occur in beds of upraised gravel, sand, and clay, the
testacea belong to recent species, yet not to that assemblage which
inhabits the ocean, but to a confined number of mixed freshwater
and marine species characteristic of the brackish waters of the Baltic.
Such deposits rise near Stockholm to the height of 200 feet above
the sea, and show that the relative level of land and sea has greatly
changed, not only since the existing testacea were in being, but also
since the Baltic was divided off from the ocean as an inland sea
freshened by a superabundance of river water.

It is well known that these parts of Sweden are densely strewed
over with huge erratic blocks, many of the largest of which oc-
cur in the highest part of ridges of sand and gravel, finely stratified
or made up of a continued series of thin layers of sand, loam, and
gravel. In one of these ridges, at Upsala, I found layers of marl,
containing perfect shells of recent species, such as live in the Baltic.
The ridge was about 100 feet high, and on the summit of it were
blocks of gneiss and granite, measuring from eight to ten feet in
length. I saw similar boulders but inferior in size overlying some
deposits of recent shells in Orust and near Uddevalla*. Hence it
is evident that the transportation of these rocky fragments into
their present position continued after the period when the modern
shelly formations of both the coasts of Sweden were accumulated.

In addition to the facts enumerated in my paper on Sweden in the
Philosophical Transactions for 1835, in regard to the agency of ice-
islands, I may mention a fact observed by Dr. Beck on the coast of
Jutland. He has ascertained that on the breaking up of the fringe of
ice which encircles the coast there during winter, small islands of ice
float off and carry with them not only small gravel from the beach
but stones four feet in diameter firmly frozen into the solid mass.
These ice-floes are sometimes driven eastward into the Cattegat, and
have been known to stop up the narrow part of the passage of the Great
Belt, and to cause new reefs of rocks thus transported on which ves-
sels, and a few years ago a Danish man-of-war, have been stranded.
If such power can be exerted by ice-islands, only a few hun-
dred feet in diameter, in latitudes corresponding to those of En-
gland, we may be well prepared to find thatislands several leagues in
circumference may remove blocks of the magnitude of small houses.

Capt. Bayfield, in commenting on the inferences which I had
drawn as to the transporting power of ice in the Baltic, communi-

* Phil, Trans., 1835, p. 33.

Geological Society. 337

cated to me several interesting facts observed by him both on the
Jakes of Canada and in the St. Lawrence. In the river last men-
tioned the loose ice, when the water is low in winter, accumulates
on the shoals, the separate fragments being readily frozen together
into solid masses in a climate were the temperature is sometimes
30° below zero. In this ice boulders become entangled, and in the
spring, when the river rises after the melting of the snow, the packs
are floated off, frequently conveying away the boulders to great di-
stances. Heavy anchors of ships lying on the shore have in like
manner been closed in and removed. He also states that immense
jce-islands, detached far to the north, perhaps in Baffin’s Bay, are
brought by the current in great numbers down the coast of Labrador
every year, and are frequently carried through the Straits of Belle-
isle between Newfoundlandand the continent of America, which, after
passing through the Straits, sometimes float for several hundred
miles to the south-west up the Gulf of St. Lawrence. In one of
these icebergs which Capt. Bayfield examined, he found heaps of
boulders, gravel, and stones, and he saw other ice-floes discoloured
by mud. Capt. Belcher also informs us that in 1815, when in
His Majesty’s ship Bellerophon he fell in with field-ice off New-
foundland, near St. John’s Harbour, in which there were muddy
streaks, gravel, and even stones: it was in the heat of summer and
torrents of water were shooting off the ice. The importance of these
phznomena will be duly appreciated by the geologist who reflects
that they relate to the annual transportation of rocks from high la-
titudes probably corresponding to those of the northern parts of
Norway and Sweden, and that the points sometimes reached by the
ice are further south than any part of Great Britain. It is there-
fore by no means necessary to speculate on the former existence of a
climate more severe than that now prevailing in the Western Hemi-
sphere in order to explain how the travelled masses in Northern
Europe may have been borne along by ice. We know from inde-
pendent evidence that large parts of the lands bordering the Baltic,
and now strewed over with erratics, have constituted the bed of the
sea at a comparatively modern period.

It may be asked whether I refer all erratics, even those of Swit-
zerland and the Jura, to the carrying power of ice. In regard to
those of Switzerland I have elsewhere endeavoured to show that a
combination of local causes might have contributed to their transfer ;
for repeated shocks of earthquakes may have thrown down rocky
fragments upon glaciers, causing at the same time avalanches of
snow and ice, by which narrow gorges would be choked up and
deep Alpine valleys, such as Chamouni, converted into lakes. In
these lakes, portions of the fissured glaciers, with huge incumbent
or included rocks might float off, and on the escape of the lake,
after the melting of the temporary barrier of snow, they might be
swept down into the lower country*.

M. Charpentier has lately proposed another theory which he in-

* Principles of Geology, vol. iii. p. 149, 1833, enlarged in later editions,

338 Geological Society.

forms us is merely a development of one first advanced by M,
Venetz. The Alpine blocks, according to these writers, were not
carried by water, for had that been the case the largest would
be either in the Alpine valleys or near the base of the great chain,
and we should find their size and number diminish as we receded
from their original point of departure. But the fact is otherwise,
many of the blocks on the Jura, or those farthest removed from
the starting-place, being of the largest dimensions. They suppose,
therefore, in accordance with the opinion of M. de Beaumont and
others, that the elevation of the Alps occurred at a comparatively
modern epoch, and that when these mountains were first upheaved
they were more lofty than now, and more deeply covered with snow
and glaciers. After the principal movement had ceased, a lower-
ing of the Alps took place, the dislocated and shattered beds re-
quiring time to settle down into their present more solid and stable
form. According to this hypothesis, therefore, the erratic blocks
are monuments of the greater magnitude and extent of the ancient
glaciers under a different configuration of the surface. I have not
space for all the ingenious arguments adduced, after a minute exa-
mination of the ground by M. Charpentier in support of this theory,
but must refer you to the original memoir *.

Before leaving this subject I may observe, that although it is rare,
in modern times, to meet with icebergs in the northern hemisphere
so far south as the Azores, in north latitude 42°, yet they have been
seen there, and not unfrequently in north lat. 44°, within the pre-
sent century, thus reaching the parallel of Southern Italy and Cen-
tral Spain. In the southern hemisphere we learn from Capt. Hors-
burgh that some large ones were carried, in 1828, still nearer to
the equator as far as lat. 35° south, or within about forty miles of
the Cape of Good Hope. I do not remember, when examining
alluvial deposits, to have seen any blocks in Sicily nor in Italy till
I approached the foot of the Alps; and in Sweden I found them in-
creasing in number and size as I advanced northwards, where I saw
some between thirty and forty feet in diameter. The erratics, theres
fore, as far as my experience extends, are a northern phenomenon 3
and M. Charpentier states, on the authority of Humboldt, that
there are no such fragments at the eastern foot of the equatorial
Andes, where, notwithstanding the altitude of the mountains, there
are no glaciers.

But assuming that ice could have transported into their present
position those myriads of angular blocks which cover the low coun-
tries bordering the Baltic, in what manner and by what force could
these masses have been detached from the mountains of which'they
once formed a part? Now the granitic rocks in Sweden sometimes
consist of large tabular masses, traversed by numerous horizontal
and vertical joints ; and entire hills may be said to be broken up,

* Sur les Blocs Errat. de la Suisse, Ann. des Sci., tom. viii. p. 219. Mr.
Bakewell has also in some one of his works alluded to the carrying of Alpine
blocks by ice.

as

Geological Society. $39

situ, into blocks of the same forms and dimensions as the erratics of
the Baltic. I remarked this particularly in Ostrogothland, near Lake
Roxen. Whether this fissuring of the rocks has been due to earth-
quakes, or the expansive power of ice in northern regions, or to what
other causes I cannot pretend to decide; but reefs of such jointed.
rocks before they emerged from the sea might have afforded an in-
exhaustible supply of detached fragments, over and around which
the ice would freeze in winter. One block after another might be
buoyed up and floated off on the rise of the Baltic when the snows
melted, or of the ocean during'high tides.

It has been suggested that large blocks may have been pushed.
far over the bed of the sea and over the land by a succession of
waves raised by earthquakes or by hurricanes. Without denying
that such agency may explain some facts in geology, I may remark
that we cannot be too much on our guard against assuming violent
catastrophes where the effects may have been brought about tran-
quilly, and even with extreme slowness. Let us imagine, for ex-
ample, a sunken reef of granite in Baffin’s Bay, in about 75° north
lat., divided into fragmentary masses as above described, and these
masses becoming year after year involved in packed ice. In a few
months they may be drifted more than 1800 miles to the southward,
through the Straits of Belleisle, to the 48° north lat., the ice mov-
ing perhaps at a slow rate—no more thanamile an hour. We
might even land upon such ice-fields and be unable to determine
whether they were in motion or not. After a repetition of these
operations for thousands of years, the uneven bed of the ocean far to
the south may be strewed over with drift fragments which have
either stranded on shoals or have dropped down from melting bergs.
Suppose the floor of the ocean where they alight to be on the rise as
gradually as the bottom of the Baltic in our own times. The change
may be so insensible that pilots may suspect, and yet scarcely dare
to insist upon the fact till its reality is confirmed by the experience
of centuries. At length a submarine ridge, covered with the tra~
velled fragments, emerges, and first constitutes an island, which at
length becomes connected with the main land,—in time, perhaps,
the site of a university like Upsala. Here the question is agitated
whether the land is stationary, or continually rising beneath their
feet. Perchance they decide that it is motionless, and yet it con-
tinues to move upwards, “ E pur si muove,” till by a growth as im-
perceptible as that of the forest tree, what was once a submarine
reef becomes the summit of an inland mountain. Here the geologist
admires the position, number, and bulk of the transported fragments ;
identifies them with the parent mountains, a thousand miles distant
to the north; and in speculating on the causes of the phenomena,
imagines mighty deluges and tremendous waves raised by the shock
of a comet, or the sudden starting up of a chain like the Andes out
of the sea, by which huge rocks were scattered over hill and dale
as readily as shingle is cast up by the breakers on a sea beach.

But it is time to return from these digressions and to consider the
other memoirs treating of these and similar subjects which have

$40 Geological Society.

been lately read to the Society. There is perhaps no class of geo-
logical phenomena in Great Britain which has hitherto remained in
more obscurity than that relating to the distribution and origin of
superficial gravel, sand, and mud, especially that which has been
called diluvium. Mr. Murchison, in his examination of the older
rocks of part of Wales and England, has made a great step towards
reducing these phenomena to order, and has thrown so much light
upon them that his treatise may be considered not only as one of
much local interest, but as likely to contribute powerfully towards
the establishment of a general theory of these deposits. He has
distinguished between the local drift, or the gravel and alluvium of
South Wales and Siluria, and that which he terms the northern drift
of Lancashire, Cheshire, North Salop, and parts of Worcester and
Gloucester. The surface of the Welsh and Silurian territories is
exempt from the debris of far-transported rocks, the alluvium there
being derived from the adjacent mountains, while Herefordshire
is chiefly covered with debris of the old red sandstone. The au-
thor, after giving a detailed description of the drainage of the
Teme, Onny, Lug, and Wye, shows that in the valleys of these
rivers the loose materials change with each successive range which
they traverse, the fragments becoming smaller in proportion as they
have been carried to greater distances towards the valley of the Se-
vern. It is also demonstrated that there is an evident connexion
between the distribution of this ancient gravel or drift and the strike
and dip of the strata in the Welsh and Silurian mountains ; and hence
it is inferred that the scattering of certain fragments took place
during the original upheaving of the mountains. But there are
other wide-spread accumulations of sand and gravel in the valleys
of the same region, which have partly been due to the existing rivers,
and partly to lakes which were drained long after the first emersion
of the country from the sea.

The above-mentioned alluvia differ entirely from another kind
of detritus, which is spread over parts of Lancashire, Cheshire, and
North Shropshire, and which consists of granites, porphyries, and.
other hard rocks, similar to those of Cumberland and some of the
Scotch mountains. To these, with their associated clay and sand,
the author gives the name of the northern drift. It has two di-
stinguishing features: first, the occasional occurrence in and upon
it of large blocks or boulders of northern origin, sometimes of great
size, like the erratics of the Baltic, and none of which ever enter
into the region of the Welsh drift; secondly, the association with
it of marine shells of existing species. This last fact was formerly
noticed by the author and Mr. Gilbertson, at Preston in Lancashire,
at heights of 350 feet above the sea. Sir Philip Egerton has since
observed the same shells in sand and gravel, north of Tarporley, in
Cheshire, at the height of 70 feet, where they occur at the western
base of the Forest Hills, about nine miles from the nearest point of
the estuary ofthe Mersey. But what is still more remarkable, Mr.
Trimmer found similar recent marine shells on Moel Tryfane, near
the Menai Straits, at the height of 1592 feet above the level of

Geological Society. 341

the sea. The same author also reported to us that he had disco-
vered similar gravel with recent marine shells overlying a peat
bog near Shrewsbury, in which were the remains of a submerged
forest. Mr. Murchison, however, having examined this spot, has
shown us that the supposed trees were stakes with sharpened puints.
driven into the ground, forming a woodwork which supported an
old road, and over these piles the shelly gravel or northern drift
had been afterwards spread artificially. I understand that Mr.
Trimmer is now fully aware of the mistake into which he had
fallen.

From the evidence afforded by the shells, as well as by the indica-
tion of several newly discovered localities where they occur sixty
miles from the nearest sea-coast, Mr. Murchison infers that the tracts
covered by them must have formed the bed of the sea during the
modern period, and as the granitic drift occupying the high grounds
east of Bridgnorth rises to the height of 500 or 600 feet, and thence
descends in a deltoid form into the Vale of Worcester, he conceives
that the sea also extended over the valley of the Severn from Bridg-
north to the Bristol Channel, so that there was then a strait sepa-
rating Wales and Siluria on the one side from England on the other.
The deposits observed by Mr. Strickland at Cropthorne and at
other points in the valley of the Avon, an eastern tributary of the
Severn, and which contain fluviatile and land shells, with the bones
of extinct quadrupeds, must, according to Mr. Murchison, have
been accumulated at the mouth of a river which flowed from the
east, or from the Cotteswold Hills, into the ancient straits above
alluded to, and into which the northern drift was prolonged.

There are sections near Shrewsbury from which Mr. Murchison
has been enabled to deduce the relative age of the two alluvial for-
mations, the local or Welsh drift having in those places been found.
covered by the clay and boulders of the northern drift. The latter
is, therefore, evidently of newer origin. As to the mode in which the
erratic blocks were transported, Mr. Murchison adverts to the
possible agency of ice-floes, and to thedifficulty of imagining that cur-
rents of water alone, whether of rivers or the ocean, could have ex-
erted a force adequate to their removal to such great distances; many
boulders of several tons in weight having been transported to more
than 100 miles from the nearest possible source of their origin.
He also infers from the position of the shells, gravel, and boulders,
that they were not washed, as has sometimes been imagined, by
one or more diluvial waves over preexisting lands, but were all de-
posited during the same period in the bed of the sea, which bed
was afterwards uplifted to unequal heights by movements of eleva-
tion of unequal intensity—movements which, though so largely
affecting the physical geography of our island, must have taken
place within the modern era.

Mr. Edward Spencer has communicated to us the result of his
examination of the “diluvium” near Finchley, and the summits of
the neighbouring hills of Highgate and Hampstead. The gravel
there contains water-worn boulders of granite and porphyry, toge-

$42 Geological Society.

ther with fragments of secondary rocks with their characteristic
fossils from the mountain limestone to the chalk inclusive. Mr,
Spencer supposes that the current which brought these materials
into their present situation must have flowed from the north. The
diluvium here alluded to seems to correspond to that which covers
the crag of Norfolk, and which is in some places intimately con-
nected with that deposit. Imay add that I have seen a similar for-
mation on the banks of the Elbe, below Hamburgh, and in other
parts of Denmark, with erratic blocks included in it in some
laces.

: Our Secretary, Mr. Hamilton, has described a bed of marine
shells, of recent species, on the southern coast of Fifeshire, near
Elie, part of the deposit being twelve or fourteen feet above the
level of high tide. Similar marine shells have been observed above
the sea-level in many of the low lands bordering the estuaries of the
Forth and Tay; and in the memoirs before mentioned Mr. Murchi-
son has described a raised beach at the mouth of Carlingford Bay,
Treland, which he lately examined in company with Professor Sedg-
wick. Mr. Dela Beche also informs us that he has lately disco-
vered proofs of two movements of the land of Somerset, Devon, and
Cornwall, one to a height of about thirty to forty feet above the
present sea-level, and another to an uncertain depth beneath it,
both subsequent to the period when the vegetation of the land and
the molluscous inhabitants of the neighbouring sea were the same
as they now are.

The evidence, therefore, is annually augmenting in favour of con-
siderable alterations in the relative level of land and sea having been
brought about in northern Europe at a comparatively modern epoch,
For this reason I am more than ever disposed to refer to great move-
ments of elevation and depression, the origin and present position of
the loess of the valley of the Rhine, of which I gave some account
in a former year. I have lately had occasion to recall your atten-
tion to this ancient silt im which terrestrial and aquatic shells are
preserved of species still living in Europe. It is found from below
Cologne to the neighbourhood of the Falls of Schaffhausen, exhibit-
ing almost everywhere the same mineralogical character and fossils,
forming sometimes low hills which cover the gravel of the great al~
luvial plain of the Rhine, sometimes rising up on the flanks of the
mountains which border the great valley to an elevation of 300 or
400 feet above the river, or more than 1200 feet above the sea. I
discovered lately, in the neighbourhood of Basle, the first remains
of fossil fish which have been detected in this silt; and Mr. Agassiz
recognized them as the vertebrz of a small species of the Shark fa-
mily, perhaps of the genus Lamna. They were associated with the
usual fresh-water and terrestrial shells, and the fact appeared ano-
malous, but the celebrated ichthyologist informs me that species of
this family and of the Skate tribe have been known to ascend from
the sea up the mouths of the rivers Senegal and Amazon to the di-
stance of several hundred miles.

Some have imagined that a great lake once extended throughout

i

Geological Society. 343

the valley of the Rhine, which sent off large branches up the courses
of the Mayne, Neckar, and other tributary valleys, in all of which
large patches of loess are occasionally met with. The barrier of
such a lake has been placed in the narrow gorge of the Rhine between
Bingen and Bonn; but this theory is untenable, as there are proofs
of the loess having once filled that gorge, and of its having over-
spread the adjoining hills of the Lower Eifel; also that it reached
to the flanks of the hills bounding the valley of the Rhine as far
down as Cologne and still further.

Instead of supposing one continuous lake of sufficient extent and
depth to allow of the simultaneous accumulation of loess at all heights
and throughout the whole area where it now occurs, I conceive that
subsequently to the period when the countries now drained by the
Rhine and its tributaries, acquired nearly their actual form and geo-
graphical features, they were again depressed gradually by a move-
ment like that now in progress on the west coast of Greenland. In
proportion as the whole district was lowered, the general fall of the
waters between the Alps and the ocean was lessened, and both the
main and lateral valleys, becoming more subject to river inundations,
were partially filled up with fluviatile silt containing land and fresh-
water shells. After this operation, when a thickness of many hun-
dred feet of loess had been thrown down slowly, and in the course of
many centuries, the whole region was once more upheaved gradu-
ally, but perhaps not equally, throughout the whole region. During
this upward movement most of the fine loam was carried off by
denudation to such an extent that the original valleys were nearly
re-excavated. The country was thus restored to its pristine state,
with the exceptionof those patches of loess still remaining, and which,
from their frequency and their remarkable homogeneousness of
composition and fossils, attest the original continuity and common
origin of the whole. By introducing such general fluctuations of re-
lative level, we may dispense with the necessity of erecting and after-
wards removing a great barrier more than 1200 feet high, sufficient
to exclude the ocean from the valley of the Rhine during the accu-
mulation of the loess.

Dr. Fitton has again brought before us those curious phenomena
in the Island of Portland from which the former alternate existence
of sea, of dry land, and lastly, of a body of fresh water in the same
place, all anterior to the formation of the chalk, has been clearly in-
ferred. In the ancient soil, called in Portland, the “ Dirt bed,” the
silicified trunks of trees and their roots are still preserved. Some
curious facts are just published on this subject in the new Part of our
Transactions, in a memoir by Dr. Buckland and Mr. De la Beche.
After Mr. Webster had first made known the nature and existence
of the dirt bed, Professor Henslow ascertained that between this
and the marine oolite of Portland there were two other beds of car’
bonaceous clay, and in one of these Dr. Fitton has now found the
remains of Cycadez, from which it appears that the forest of the
dirt bed was not the first vegetation which grew on this tract. First
there must have been the sea of the oolite, then land which sup-

344 Geological Society.

ported Cycadez, then a lake or estuary in which freshwater strata
were deposited, then again land on which other Cycadez and a fo-
rest of dicotyledonous trees flourished ; then a second submergence
under fresh water, in which new strata were formed ; and finally, a
return of the ocean in the South-east of England, when the green-
sand and chalk were superimposed upon the Wealden. The ap-
pearances in Portland alluded to by Dr. Fitton may be explained
either by the alternate rising or sinking of the same ground, or by
simply supposing one gradual and continuous subsidence in a region
where a large and turbid river entered the sea. The conversion of
certain tracts into land several feet high might be caused in a single
year by river-inundations, and there might be sufficient time for a
forest to grow upon these before the continued sinking down of the
land (assuming it to have been constant) had time to cause the tract
to be again submerged. I have before adverted to the petrified
forest described by Mr. Darwin, in Chili, where the trees have grown
ona bed of lava, and have then been covered by sand and sedi-
mentary and volcanic matter 2000 feet thick. These facts seem to
prove that the region of the Andes, instead of having been raised
up suddenly and at once, a few thousand years before our time, as
some have conjectured, has undergone, even since the commence=
ment of the tertiary period, vast movements of depression as well
as of elevation.

Among the modern changes of the surface of the globe which
have been attributed to a depression of the earth’s crust, I may men-
tion the great cavity in Western Asia spoken of by Humboldt in his
Asiatic Fragments. ‘The supposed existence of a region of dry land
18,000 square leagues in area, surrounding the Caspian Sea, and be-
low the mean level of the ocean, naturally excited the most lively
curiosity. The fact was regarded for twenty years as established
by a series of barometrical measurements made in 1811 by Profes-
sors Engelhardt and Parrot. The difference of level which these
travellers assigned to the Caspian and Black Seas amounted to about
350 feet. But Professor Parrot, having revisited the tract in 1829 and
1830, soon found reason to doubt the accuracy of his former conclu-
sions. He learnt that some Russian engineers had ascertained by
careful measurements that the Don, at the place called Katschalinsk,
where it is only sixty wersts distant from the Wolga, is 130 Paris
feet higher than the latter river, and as the Don flows with much
greater rapidity to the Black Sea than the Wolga does to the Cas-
pian, the difference of level between the two seas, if any, must be.
considerably less than 130 feet. Parrot accordingly made a series
of levellings from the mouth of the Wolga to Zarytzin, 400 wersts
up its course, and from the mouth of the Don to the like distance ;
and these observations gave as a result that the mouth of the Don
was between three and four feet lower than that of the Wolga!
So that, according to this measurement, if there is any difference
between the levels of the two seas, the Caspian is the highest!
Baron Humboldt, who with other geographers had given full credit
to the former statement of Parrot, very naturally refused to admit

Linnean Society. 345

the validity of these new observations, unless the Professor was pre-
pared to show that his former ones were less worthy of confidence,
In reply to this, Professor Parrot, in his Appendix, admits that the
barometrical instruments used in 1811 were imperfect, and that his
former calculations also were in some respects inaccurate.

It appears tome perfectly natural that Baron Humboldt, M. Arago,
and others, should have willingly admitted the supposed fact of a con-
siderable variation between the levels of the Caspian and Black Seas.
It is well known that the Mediterranean sustains its level at nearly
the same height as the ocean, by drawing largely from the Atlantic
on one side and from the Black Sea on the other. But if these
constant supplies of water were cut off, if the Straits of Gibraltar
and Constantinople were closed, and the Mediterranean became an
inland lake isolated like the Caspian, its level must immediately fall.
Its loss, by evaporation, would not be counterbalanced by the influx
of river water, and there would then exist around its borders a tract
of dry land lower than the ocean. It is true that we have no data
for deciding to what extent this depression of level would reach; but
it would present, at least on a small scale, a phzenomenon analogous
to that supposed to have been established in the case of the Cas-
pian.

With every inclination to acknowledge and duly to appreciate the
honest zeal with which Professor Parrot has laboured to correct his
first error, 1 may remark that it does not yet appear why three or
four years were lost after 1829 in putting the scientific world on
their guard, and above all why the author of the Asiatic Fragments,
published in 1831, was allowed to remain in ignorance of results
previously obtained.

Gentlemen, I have now endeavoured to lay before you a brief
sketch of the principal subjects referred to in the papers and in the
discussions which have engaged the attention of the Society during
the last year. I have confined myself exclusively to our own Pro-
ceedings ; for the limits of this address would not allow me to give an
analysis even of all the English works on Geology which have ap-
peared since our last Anniversary, still less of all those which have
been published on the Continent. A brief notice of these last would
indeed require a volume, and this fact alone should inspire us with a
feeling of strength and confidence in the future progress of Geology,
which although it had scarcely obtained a recognised place among
the sciences towards the close of the last century, has already risen
into such importance as to excite a general interest in every nation
throughout the world where the works of nature are studied.

LINNEAN SOCIETY.

Dec. 15, 1835.—A communication from Charles C. Babington,
Esq., M.A., F.L.S., on several new or imperfectly understood
British and European Plants, was read.

Among the species whose history is elucidated in this paper are
the following, viz.

Third Series. Vol. 8. No.47. April 1836. 2M

346 Rvological Society.

1. Crepis virens, L. This is the Crepis tectorum of British au-
thors, which must henceforth be removed from our Flora,
C. virens has the leaves even at the margin, the achenia smooth,
and shorter than the pappus. C. tectorwm has the leaves revolute at
the edges, and the achenia scabrous, equalling the pappusin length.

2. Habenaria chlorantha, and bifolia. The former is the Orchis
bifolia of Fl. Brit, and Engl. Bot., and the latter is the difolia of
Linnzus, as is proved by the specimen in his Herbarium, and is
identical also with the Platanthera brachyglossa of Reichenbach.

Among the additions to the British Flora we may reckon the
following: Ist, /Zerniaria ciliata, a species hitherto confounded
with glabra; from which it is principally distinguished by its ovate
ciliated leaves, The Cornish habitat for glabra belongs to thisspecies.
2ndly, Polyzonum maritimum, L., found by Mr. Borrer on_ the
sandy shore near Muddiford. 3rdly, P. Razz, the marinum of Ray’s
Synopsis, and the aviculare e of Smith. 4thly, P.dumetorum, L.,
an interesting addition discovered by Mr. Hankey in a wood near
Wimbledon. 5thly, Luphorbia corallioides, L., found at Slinfold,
Sussex, and perhaps scarcely to be reckoned indigenous. It is the
pilosa of the Ist edit. of Hooker's Brit. Flora. 6thly, Erica
Mackait, a species discovered on Craigha Moira, Cunnemara. In
its essential characters it approaches to E. Tetralix; but in habit it
resembles E. ciliaris.

March 1.—His Grace the Duke of Somerset, President, in the
chair.

Some account of a species of Agave introduced accidentally into
the Deccan; by Lieut.-Col. Sykes, F.R.S. &c.,—was read.

A number of young plants of this species came up accidentally
in the garden of the collector at Poonah, in a border that had been
appropriated the year before to a collection of bulbous roots that
had been obtained from the Cape of Good Hope. One of the

lants flowered in the fifth year after their first appearance. The
height of the flower-stem was 25 feet. Although the fowers were
apparently perfect, no seeds were produced. After the flowers had
fallen, a multitude of small bulbs were produced on the branches.
The species proves to be identical with the Agave cubensis, a plant
discovered by Jacquin in the island of Cuba. It belongs to Ven-
tenat’s Fourcroya, a group of species distinguished from the normal
Agaves by their dilated filaments, and by the thickened base of the
style.

arn 16.—Read a continuation of Dr. Hamilton’s Commentary
_on the Hortus Malabaricus.

ee

ZOOLOGICAL SOCIETY.

November 10, 1835.—At the request of the Chairman, Mr. Gould
exhibited a specimen of the true Lanner Hawk, Falco Lanarius, Linn.,
and entered into some details with respect to its distinguishing pe-
culiarities. Its real characters, he stated, have hitherto been so im-
perfectly understood as to have led to very general doubts as to its
existence as a distinct species.

Mr. Gould also exhibited specimens of two species of Pheasant,

Zoological Society. $47

. both of very great rarity, which had recently come into his posses-
sion: they were the Phasianus Semmeringii, Temm., and the Phas.
versicolor, Ej. He accompanied the exhibition by some remarks on
the subdivisions which appear to him to be required among the Pha-
sianide generally ; and more especially on the position, among that
extensive group, of the species exhibited.

Mr. Bell read ‘‘ Some Account of the Crustacea of the Coasts of
South America, with Descriptions of New Genera and Species;
founded principally on the Collections obtained by Mr. Cuming and
Mr. Miller. (Tribus 1, Oxyrhynchi.)”

The skeleton was exhibited of a Coypus, Myopotamus Coypus,Comm.,
together with preparations of some of the viscera obtained from the
same individual, which recently died at the Society's Gardens. With
reference to them some notes by Mr. Martin were read, which are
given in the Proceedings.

Mr. Christy subsequently exhibited several skins of the Coypus,
for the purpose of directing the attention of the Meeting to the po-
sition of the mamme in the female, which are situated extremely high
up the sides.

Nov. 24.—Mr. Yarrell exhibited a specimen of the SyngnathusAcus,
Linn., with the view of again* calling the attention of the Society
to the fact that the males in this species of Pipe-fish are furnished with
a pouch under the tail, in which they bear about with them the ova
until the young have escaped from the capsule; and which probably
serves also as a place of shelter to which the young can, for some
time after their exclusion, retreat in case of danger. In this indivi-
dual the opened abdomen exhibited the preparatory organs of the
male; and the displayed subcaudal pouch showed many eggs con-
tained in it, the young of which were fully developed and ready to
escape from the capsules, while from others the young had actually
escaped. As a guide to those observers who may be desirous of
procuring specimens equally illustrative of the peculiarity of this
fish, Mr. Yarrell mentioned that the individual exhibited was ob-
tained on the 20th of July.

Mr. Yarrell read some “‘ Notes on the Economy of an Insect destruc-
tive to'Turnips”; which he prefaced by adverting to the importance
to agriculture of an attentive collection of those entomological facts
which relate to species injurious to the ordinary crops of the farmer.
He then proceeded to remark that the turnip crop is in this country
usually infested in every season by two species of Haltica; and that
another destroyer has been, in the dry summer of this year, super-
added to them, especially on the light and chalky soils. To the
history of this latter pest, which has been known to occur in those
seasons only in which there has been an almost total absence of rain,
Mr. Yarrell’s paper is directed. A good account of a similar visita~
tion in 1782, as it was observed in Norfolk by Mr. William Marshall,
was published in the ‘ Philosophical Transactions’ for the following
year.

Early in July last the “‘ yellow fly ” was seen upon the young tur-

* See Lond. and Edinb. Phil. Mag., vol. vi. p. 383,
2M2

ms

248 Royal Institulion.

nips. It was remembered by some farmers that this was the fly .
which prevailed in the year 1818, and which was followed by the
caterpillars known by the name of the blacks. The eggs being depo-
sited by the perfect insect in the leaf of the plant, the black cater-
pillar or turnip-pest speedily makes its appearance, feeding on the
soft portions of the leaves of the turnips and leaving the fibres un-
touched; and finally, casting its black skin and assuming one of a
more slaty or grey colour, it buries itself in the earth. Lodged there,
it forms for itself, from the soil, a strong oval cocoon; from which
some of the earlier broods pass almost immediately into the perfect
state, filled with ova, and ready quickly to supply another generation
of destroyers. So compiete and so rapid was the destruction in some
instances, that a whole field was found, in two or three days, to pre-
sent only an assemblage of skeletonized leaves; and this too when
the turnips had attained a considerable size.

The insect whose proceedings have heen thus briefly noticed, be-
longs to the Hymenopterous family Tenthredinide ; it is the Athalia
Centifolie, a species first noticed by Panzer. Mr. Yarrell describes
the perfect insect and the caterpillar; and then recurs to the damage
effected by the latter. By their repeated broods the devastation was
continued for so long a time that even the third sowing did not in all
cases escape destruction ; and it was not until the occurrence of the
heavy rains in September, terminating the unusually dry summer,
that the mischief ceased. The destruction of the leaves caused, in
most instances, the loss of the root also; and where the leaves suf-
fered from the attacks of the black caterpillar, but not sufficiently to
occasion the death of the plant, the turnip itself became pithy and
of little value. It has become necessary, Mr. Yarrell states, to im-
port the root largely from the Continent to supply the deficiency of
the home crop.

The remedial measures adopted on a former visitation were the
turning into the infested fields of a large number of ducks, who
greedily devoured the caterpillars as they were brushed from the
leaves by a boy with a long pole; the passing of a heavy roller over
the ground at night, when the caterpillars were at their feed; and
the strewing of quick lime by broad cast over the fields, renewing
it as often as it was dispersed by the wind. The latter mode was
generally considered as the most effectual preservative.
PROCEEDINGS AT THE YFRIDAY-EVENING MEETINGS OF THE

ROYAL INSTITUTION.

Jan. 22, 1836.—Mr. Faraday on silicified plants and fossils, and
the proposed theories of silicification.

Jan. 29.—Dr. Ritchie. A view of the differential and integral cal-
culus.

Feb. 5.—Mr. Brande on the manufacture of paper-hangings.

Feb. 12.-Dr. Grant on the structure of fishes, considered with
reference to their aqueous element.

Feb. 19.—Mr. Faraday on the magnetism of metals as a general
character (see page 177).

Intelligence and Miscellaneous Articles. $49

Feb, 26.—Dr. Lardner on steam communication witli India.

March 4,—Mr. Fox on a mode of laying out and working oblique
or askew bridges. (See p. 299 of the present Number.)

March |1.—Dr. Arnott on warming and ventilating buildings.

March 18.—Mr. Wheatstone on the means of investigating the
structure of crystalline bodies by their sonorous vibrations.

LXV. Intelligence and Miscellaneous Articles.

ON THE ATTRACTIVE AND REPULSIVE FORCES OF MAGNETS AT
VERY SMALL DISTANCES.

Note applicable to the Correspondence between Professor Ritchie and
Mr. R. W. Fox, (see our last four Numbers,) on the attractive and
repulsive forces of magnets at very small distances. Extracted by
a Correspondent from a paper by W. Snow Harris, Esq., F.R.S.,
in the Trans. R.S. Edinburgh, 1831; dated July 1, 1827.

£ JN the following table are the results of a series of experiments

with the attracting and repelling poles. The magnets em-
ployed are indicated by the letters a, b, c, d, e, their dimensions be-
ing as follows:

a, A small cylindrical magnet 2 inches long, 0°2 of an inch in dia-
meter, and similar in every respect to the suspended magnet zx
[on which its force was exerted ].

, 4°5 inches long, and 0-4 of an inch square,

, 70 inches in length, and 0-7 of an inch diameter.

, 9:0 inches long, 0:8 of an inch wide, and 0°3 of an inch thick.

» 14-0 inches long, 1:0 inch wide, and 0°5 of an inch thick.

D signifies the distance ; whilst the letters a, b, c, d, e are placed
over the respective forces.”

Lee

is)

; Dissimilar Poles. Similar Poles.

a | 6b e | d e a bie d e
4 oh ae 34+ pe | vse] oes 3-4
Brel os Aae Se 4+ nea iepe Heer etl eae 4°
mae, ss ieee Gian) Oe Wesel cselpe caret ine |i
25) . | ne} os 85] 5 eval h tases wes Mec 8+
ie Pog (2504 3 13° | 3 1.202 [O19 les Wh 18s
18) «| .. 3+ | 35+) 165 | & ode freee’) 125/034]! W544
1G ites e! j}iies 4: AD 4) 21: Hwee [lesen lbemaral| aot 4+) 185
0 ec 45 5:5 | 23 estas, lespcenll tide 5+ iO;
MEAN Messiaen 55 — 0-28") | eS | se. | ore | 475), 5'5 2G
Teed RCo bes WRU ih MD
1° | 15 | 2. 10° 12: 49° 3 15 Q2- | 7% 9: 33°
08) 2+) 3+/15: | 21 acre Nea, 2° | 3° !1o- | 11-9] 4a
06) 4° | 6—|25°-+ 132 ey 3:+:| 5° 114: ,), 14: .| 56°
05) 6°" | Br 3s", | 40 [4° | 65 15:5) 14-4) 60-
0°4| 9° rag : Ot U7: aloo te come
*3/15* | |18° | I vos

“These experimental results are quite consistent with the opera-
tions of the inductive influence [before explained]. We immediately
perceive, by referring to the attractive forces, that the law of the in-

* At these distances the repulsive force was superseded by attraction,

350 Intelligence and Miscellaneous Articles.

verse square of the distance is manifest through all the approximations,
except a few of the last, the occasional irregularities observed being
very inconsiderable ; so that when the magnets are very nearly approxi-
mated in relation to their respective intensities, the increments in the
forces begin to decline,—a circumstance of considerable importance
in our endeavours to investigate the laws of magnetic attraction ;
for it may be supposed that the inductive influence which thus begins
to vary, may at last so far vanish, even before contact, that the abso-
lute force, at near approximations, may in some instances, as already
stated, be in an inverse SIMPLE RATIO OF THE DISTANCE™, and which was
observed to happen with the bars marked d and e. For although the
cylindrical counterpoise employed in these experiments did not admit
of the forces being examined at nearer approximations than those
marked in the table, yet by substituting one of large dimensions the
forces may be carried on nearly up to the point of contact, so as to
be estimated in terms of the preceding progression, since the degrees
of attraction may be always compared and valued in grains of abso-
lute weight.”

‘In the following table are the results ofthe experiments so con-
tinued with the magnets d and e ; the counterpoise being 1:0 inch in
diameter, 1° of attraction corresponding to 10° of the former, and
being equal to two grains of absolute weight :”

Dissimilar Poles.

D d | e
0-4 | 6 | 18
0-3 | 85 | 24
0-2 | V3: | 36

“Tt may be perceived in this table, that the corresponding forces
at near approximations, do not materially vary from a simple inverse
ratio of the distance.”

« This deviation from the law of the inverse square of the distance
observed in all the near approximations of the magnets may happen
either in consequence of the distant polarities having passed a certain
limit, or otherwise from the inductive action not going on with the
same freedom at some point approaching saturation. The latter
would seem to be extremely probable ; for it has been already shown,
that when two dissimilar polarities are opposed to each other, their
free action becomes more or less neutralized.” ——T7vaus. of Royal So-
ciety of Edinburgh, vol. xi. p. 310—312. W. J. A.

ON THE AURORA OF THE 18TH NOVEMBER LAST.
Communicated by Professor Rigaud.

During the beautiful aurora which took place on the 18th of last
November, it is remarkable that Mr. Sturgeon was not able to see
any of its light excepting in the north. Dr. Robinson, in the last
number of the Phil. Mag. (p.236.), has drawn an important conclu-
sion from this circumstance; it may be right, therefore, to state

* The Italics and capitals in this passage are our Correspondent s.—Eprr.

Meteorological Observations of the Royal Society. 351

that in Oxford the streams of light rose and continued for a con-
siderable time to pass far beyond the zenith. A little, also, after
nine o'clock, an arch like a Jong, luminous, narrow cloud extended
from about the E.N.E. or N.E. by E. nearly across the heavens. It
appeared to have an altitude of about 60° where it cut the southern
meridian. ‘The approximation of this situation to that of the mag-
netic equator would have given great value to this phenomenon, if
the arch had been more definite in its form, and the place could have
been more accurately determined in which itreached the horizon ;
but this last circumstance could only be collected from its passing
near Jupiter.

The Oxford Herald of the 21st mentioned that this arch had been
also observed at Banbury.

NOTE ON MR. ATKINSON’S PAPER INSERTED IN THE LAST
NUMBER OF OUR JOURNAL, PAGE 188.

We regret that we should have given currency to a paragraph in
the above-mentioned paper, which seems to imply a degree of negli-
gence on the part of the Assistant Secretary at the Royal Society’s,
whose duty it is to make and record the Meteorological Observations
there. If Mr. Atkinson had taken the precaution to make inquiries
at the apartments of the Royal Society, he would have found that the
anomalies and apparent errors to which he alludes are not owing to
want of care and attention on the part of the Assistant Secretary, but
to the position in which the instruments are placed ; which position,
although evidently not a good one, is the best which the locale of the
Society presents. The instruments are all of the best kind, and of
superior accuracy and workmanship.—Eprr.

METEOROLOGICAL OBSERVATIONS FOR FEBRUARY 1836.

Chiswick.—February 1. Slightly overcast : fine. 2, Hazy: rain: baro-
meter extremely low. 3. Rain. 4. Wet and stormy. 5. Hazy and cold.
6. Very fine. 7. Drizzly: cloudy and'mild. 8, 9. Overcast. 10. Showery.
11. Clearand cold, 12,Cold and windy. 13.Sharp frost: fine. 14. Fine.

15. Clear and frosty. 16. Frosty. 17, 18. Clear, cold and windy.
19, 20. Sharp frost: fine but cold. 21. Frosty: clear. 22, 23. Overcast.
24, Overcast : fine. 25. Frosty: fine. 26. Sleet; rain. 27. Drizzly.

28. Hazy: cloudy and fine. 29. Overcast.

During the first three days of the month the barometer fell remarkably
low, and particularly on the 2nd, on which day it was lower than it has
probably been for many years in the vicinity of London. The fall of rain
was notremarkably great, nor was the temperature at nights below freezing ;
but in the country the fall of snow was, at the same time, unusually deep,
and the storm so excessively violent that the mails were in many instances
obstructed in consequence.

Boston.—¥ebruary 1. Cloudy and stormy: rain early a.m. 2. Fine: snow
pM. With rain. 3. Cloudy: rain early a.m. 4. Cloudy and stormy : rain
P.M. 5. Cloudy. 6. Fine. 7. Cloudy: rain early a.M.; rain p.m.
8. Cloudy: rainr.m. 9. Fine. 10, Rain: rain p.m. 11, Fine and stormy.
12. Stormy. 13.Fine. 14, Cloudy. 15. Fine. 16.Cloudy. 17. Stormy:
snow a.M.and p.m. 18. Stormy. 19,20.Fine. 21.Cloudy. 22. Fine.
23—25. Cloudy. 26, Cfoudy: rain rm. 27. Cloudy. 28. Cloudy:
raine.M, 29, Rain.

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THE

LONDON ann EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]

MAY 1836.

LXVI. On the Action of Hydrochloric Acid on certain Sul-
phates, and particularly on the Sulphate of Copper. By
Rosert Kane, M.D. M.R.LA.*

HE following experiments were instituted in consequence

of some results casually arrived at, whilst engaged on
another subject ; and as they possess a certain interest with
regard to the theory of the hydracids, and are also additions
to the number of real facts in chemistry, I have considered
them deserving of the notice of the Royal Irish Academy.

When bluestone (S+ Cu) +5 H, is dissolved in liquid mu-
riatic acid, there is produced a considerable reduction of tem-
perature, viz. from about 65° to about 35°. The solution
becomes deep grass green, and by evaporation yields needles
of hydrated chloride of copper. If there is taken a quantity
of sulphate of copper corresponding to the atomic weight, and
a quantity of liquid muriatic acid corresponding to an atom of
dry acid, and the solution be effected by heat, on cooling,
the whole solidifies into a fibrous mass of hydrated chloride
of copper, and there is no bluestone remaining undecomposed.
The sulphuric acid remains in the water. When the atomic
proportions are not accurately preserved, small crystals of
bluestone are scattered through the mass of chloride; but the
latter can be obtained pure by carefully attending to this
point. In this reaction we have evidently a complete in-

* Communicated by the Author,
Third Series. Vol. 8. No. 48. May 1836. 2N

354 Dr. Kane on the Action of Hydrochloric Acid on

version of the ordinary rules of chemical affinity. The sul-
phuric acid ranks much higher in affinitary [?] power than the
muriatic acid, and yet is completely displaced by the latter
from its state of union with the black oxide of copper. The
theory of this reaction is very easily understood. ‘These are

(S + Cu +5H)+ CIH, and there are. formed (Cl + Cu)

+S+6H. The sudden liberation of the larger quantity of
water from its state of solidity in bluestone produces the re-
markable reduction of temperature.

I have sometimes observed that when the crystallized chlo-
ride of copper is allowed to remain for a long time in contact
with the strongly acid mother-liquor, a reverse action is set
up, and small crystals of sulphate begin to appear disseminated
through the mass. I several times analysed these crystals, in
order to ascertain whether a sulphate of the chloride of copper,
like Peligot’s chromate of the chloride of potassium, would
be formed, but without effect ; no definite compound could be
detected.

The interesting nature of this reaction made it important to
ascertain the action of sulphate of copper upon dry muriatic
acid gas. ‘The experiments for this purpose were conducted
in the following manner. A bulb tube was connected at the
ends with strong glass tubes containing fragments of dried
chloride of calcium. The one tube was by its other extremity.
connected to a retort, in which muriatic acid gas was disen-
gaged by the action of oil of vitriol on fused chloride of so-
dium. ‘The other desiccating tube was of much smaller size,
so as to allow of being weighed in a delicate balance ; to the
remote extremity of this a small quill tube was attached, by
which the excess of gas made its escape. ‘The sulphate of
copper in fine powder was introduced into the weighed bulb
tube, and the whole then weighed to determine the quantity
employed ; the desiccating tubes were then attached, and the
muriatic acid gas disengaged. Having been dried in its pas-
sage over the first chloride of calcium, it came into contact
with the bluestone, by which it was rapidly absorbed; and any
water that was formed or disengaged, carried away by the
current of dry gas in excess, was deposited in the small de-
siccating tube, where its quantity could be accurately deter-
mined.

When the crystallized bluestone (S Cu+5 H) in fine pow-
der is put into the tube, it absorbs rapidly thé$muriatic acid
gas, and becomes grass green: great heat is produced. Drops
of moisture appear on the cold portions of the tube. It loses

certain Sulphates, and particularly Sulphate of Copper. 355

its pulverulent texture, and is converted into a mass of silky
pale green crystals: on the heated portions of tube, points of
a chocolate brown matter are produced. The current of gas
being continued until all action ceased, and the tube and its
contents had cooled to the ordinary temperature of the room,
the apparatus was weighed, and the bluestone was found to
have absorbed rather more than one atom of muriatic acid,
the excess being attributed to the quantity absorbed by the
water disengaged.

The mass of green crystals thus obtained is very delique-
scent, excessively acid, and gives fumes, arising probably from
some muriatic acid in excess. Dissolved in water it yields
by crystallization the hydrated chloride of copper in long
needles.

When there is used sulphate of copper, either quite dry, or
retaining one atom of water, the effect is so nearly similar as
to allow of the same description serving for both.

S Cu or S Cu H absorb muriatic acid rapidly, and assume
a dark chocolate brown colour. The mass becomes slightly
coherent as if some water became free; but the second desic-
cating tube does not increase in weight in any perceptible de-
gree. The process is accompanied by the evolution of so
much heat as occasionally to crack the tubes; but the passage
of the gas must be continued for a long time after the whole
has become cold. The amount of gas absorbed then approxi-
mates very closely to one atom, but it seldom absolutely at-
tains the theoretical quantity; it can approach, however,
within one per cent., and we may consequently consider that
one atom is the quantity absorbed.

This brown matter is possessed of interesting properties.
When heated it gradually and readily parts with its muriatic
acid gas, leaving behind the sulphate of copper unaltered.
Exposed to the air it rapidly absorbs water, with the evolution
of heat, and becomes apple green, a change which occurs
instantaneously if a few drops of water be allowed to fall upon
it. Dissolved in water it forms an apple green solution ; and
by crystallization gives the crystallized chloride of copper,
sulphuric acid remaining in the liquor.

Two theories may be conceived of the nature of the body
thus formed: One, that the chloride of hydrogen is absorbed
by the sulphate of copper and combines with it as water would
do,—that, in fact, the so-called muriatic acid is capable of re-
placing the water of crystallization of salts as ammonia and
phosphuretted hydrogen have been shown to do by Rose and
Graham: The other, that the chloride of hydrogen reacting

on the oxide of copper forms water and chloride of copper,
2N 2

356 Dr.Kane on the Action of Hydrochloric Acid on Sulphates.

while the latter with the sulphuric acid constitutes a sulphate
ofa chloride. The general nature of its properties inclines
me to believe the former to be the true idea, that the chloride
of hydrogen exists as such in the brown powder, and that
chloride of copper is only formed when the decomposition is
effected with the presence of much water.

The singular results of the reaction just described render-
ing an examination of the influence of muriatic acid on the
sulphates in general highly interesting, experiments were in-
stituted, of which the results shall be very briefly stated. —

Dry muriatic acid was passed over sulphates in the appa-
ratus before described. With the sulphates of potash, soda,
zinc, magnesia, iron, alumina, and lead, no action was ob-
served ; these salts did not change in weight or in appearance.
On the other hand, the sulphates of nickel and of quicksilver
absorb muriatic acid very gradually, with the evolution of
heat, the absorption ceasing when half an atom has been
taken up. These compounds lose the gas they had absorbed,
by exposure to the air during some time, and immediately on
being heated. If they be put into water, the sulphate is de-
posited pure, the muriatic acid remaining in the water.

Sulphate of potash dissolves in liquid muriatic acid with
some evolution of heat; and if by means of heat two atoms of
sulphate of potash be dissolved in a quantity of liquid con-
taining an atom of real muriatic acid, there separate on cooling
finely formed crystals (rhomboidal plates) of bisulphate of
potash, with opake cubes of chloride of potassium. A great
number of analyses of the crystals obtained by such reaction
was made to determine whether the sulphate of chlorkalium
corresponding with the chromate had any existence, but no
trace of its being formed could be obtained. Bisulphate of
potash crystallizes from its solution in liquid muriatic acid
unaltered. Sulphate of ammonia similarly treated gives pre-
cisely similar results.

It has been long known that Glauber’s salt treated with
muriatic acid constitutes a powerful freezing mixture, the
theory of which is at once explained by the results of the expe-
riment. When sulphate of soda is dissolved in liquid muriatic
acid there are formed bisulphate of soda and chloride of so-
dium, and as the former salt crystallizes only with four atoms
of water, the remaining quantity of the water of crystallization
of the Glauber’s salt is disengaged, to the amount of sixteen

atoms: thus, 2 {(S+Na)10 H}+(Cl+H) =
{(2 S+Na) +4 H)} +(Cl+ Na) +17 H.

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 357

This large quantity of water suddenly separated from a state
of combination in which it had been solid, produces, by its
absorption of caloric of liquidity, the frigorific property.

The sulphates of zinc and magnesia dissolve in muriatice
acid, and by cooling or evaporation are obtained unaltered.
The muriatic acid does not appear to produce any change of
nature.

When protosulphate of iron is dissolved in muriatic acid,
the liquor furnishes by crystallization quantities of unaltered
sulphate and of chloride of iron. Sometimes the sulphate re-
tains its common quantity of water of crystallization, but at
others I have obtained a salt giving by analysis:

Sulphuric acid 18°7 S = 195
Protoxide of iron 16°7 Fe = 17°3
Water and loss 14°6 gH = 13-2

50°0 50:0

The crystals were always so aggregated that their form
could not be accurately determined ; they are transparent,
harder, and of a much lighter green than ordinary copperas ;
they are quite permanent, and when dissolved in water give
sulphate of iron with the ordinary quantity of water.

The sulphate of alumina crystallizes unaltered from its so-
lution in muriatic acid, bué in more beautiful plates than from
water. From the solution of sulphate of nickel or of mer-
cury in muriatic acid, these salts are deposited by crystalliza-
tion unchanged.

23, Lower Gloucester Street, Dublin: March 25, 1836.

LXVII. An Abstract of a Memoir on Physical Geology ; with
a further Exposition of certain Points connected with the
Subject. By W. Horxiys, £sq., M.A., F.G.S., of St. Peter’s
College, Cambridge.

[Continued from p. 281, and concluded. ]

IV. npHE two systems of fissures which I have described

are those which must be regarded according to this
theory as primary phenomena, from which, as before stated,
the secondary phenomena of mineral veins, faults, anticlinal
lines, &c., must be derived. For this second part of the sub-
ject, I must refer to the second Section of my Memoir, where
T have entered in detail into the manner in which these latter
phienomena may be conceived to be derived from the former.
The number of phenomena which we are thus enabled to
account for, as the consequences of a simple cause from which

358 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

they are deducible by strict mechanical reasoning, appears to
me, in the present state of our speculations and practical
knowledge, to give to the theory 1 have been attempting to
develop the strongest claim to the attention of geologists.

It will be observed, that a most essential part of this theory
consists in the relation which it assigns between the directions
of dislocation and the general configuration of the elevated
mass at the instant previous to its rupture. It may, at first
sight, appear impossible to ascertain what this form may have
been, now that we can only examine the mass in its dislocated
state; but this difficulty, though it must always exist in a
greater or less degree, will not appear so serious a practical
one, when we consider that since necessary relations must
exist between the form of the mass at the instant above men-
tioned, and the lines of dislocation, and again between these
lines and the actual disturbed form of the mass, some such
relations must also exist between this latter and the previous
form. Thus if the actual form be approximately conical, we
may conclude it to have been also conical at the instant of
dislocation; and if the disturbed district be of great length
as compared with its width, and presents a well-defined axis
of elevation, we may conclude the unbroken elevation to have
been approximately cylindrical. Partial elevations which may
have been superimposed upon a general one, as already de-
scribed, at the instant previous to dislocation, must generally
be more difficult to detect, since it*may frequently be impos-
sible to distinguish present indications of them from similar
elevations which may have been produced by the elevatory
force entirely subsequently to the formation of the fissures.
On such points the observer must of course exercise his dis-
crimination and judgement. Deviations from rectilinearity or
parallelism in the lines of dislocation are not to be regarded
necessarily as anomalies. We frequently speak, it is true, of
the law of parallelism in such phaenomena, as if that were
their essential characteristic, but it is manifest that, according
to our theory, this is only a secondary property in them, de-
pending on the rectilinearity of the general axis of elevation.
In conical elevations such as those before alluded to (p. 233)
there is no approximation to parallelism in the observed fis-
sures; and if the general axis of elevation be curvilinear, the
longitudinal fissures preserving their parallelism with it (ac-
cording to theory) will be also curvilinear, while the trans-
verse fissures perpendicular to the former at their points of
intersection will no longer be parallel. ‘These deviations from
rectilinearity and parallelism are due to the action of the ge-
neral elevatory force, and to the nature of the general eleva-

Mr. Hopkins’s Abstract of his Memoir on Physical Geoiogy. 359

tion. Others more limited may be due to partial elevations.
Where they are observed, the local configuration of the mass
must be examined, and thence the directions of the conse-
quent tensions superimposed on that of the general mass must
be inferred. The equation of.page 273 will then determine the
resulting directions of the fissures, and therefore the nature of
the deviations. In simple cases, the remarks in page 276-277
will enable us to do this with sufficient accuracy to compare
the theoretical deduction with the observed pheenomena,

V. It has already. been stated, that all consideration of
those portions of the earth’s crust, in which a regularly jointed
or laminated structure may have prevailed previous to their
elevation, has been excluded from the investigations contained
in my memoir, because I wished to keep them distinct. from
any speculations respecting the operation of other causes than
the one whose effects I proposed to develop. In our general
speculations, however, on theories of elevation, it is necessary
to consider how far these dislocations which, according to the
theory I have been discussing, must be regarded as primary
phenomena, areanything more than secondary ones, depending
on lines of less resistance, produced by some such particular
structure as that above mentioned. Much valuable informa-
tion respecting joints may be expected from the forthcoming
work of Professor Phillips on the Geology of Yorkshire; but
at present we know but little accurately about this important
feature in the structure of rocks, and of its cause, I conceive,
absolutely nothing. We have, therefore, no positive reason
to conclude that this peculiarity of structure has generally
been superinduced after the elevation of the mass in which it
exists, though in some cases there appears little doubt of
such having been the fact. It is highly important, however,
to determine whether any perfect coincidence does exist in
the directions of dislocation, and of joints in the same district ;
and it is to be hoped that geologists will direct their earnest
attention to this subject. Should this coincidence be esta-
blished generally in districts where the fractures are parallel
and at right angles to each other, it will still be important to
ascertain how far it exists in elevations approximating to the
conical form ; and, in all cases, whether the directions of joints
bear any relations to the configuration of the mass, as mo-
dified by partial elevations. All these are points of interest
which we may hope by accurate and careful observation to
determine. Should the coincidence, however, between joints
and lines of fracture be perfectly established, we shall still
have to consider whether the joints, by their prior existence in
the undisturbed mass, have determined the lines of fracture, or

360 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

[whether] these latter phanomena have exercised an influence
in determining the positions of the joints, supposed to be sub-
sequently formed in the elevated mass. Now, assuming the
coincidence just mentioned, there must of course be the same
relations between the general conformation of the elevated
mass and the directions of joints, as those which have been
already stated to exist between that conformation and lines of
dislocation; and therefore, if we assume the prior existence
of joints, and also that the lines or axes of elevation have been
principally determined by the points of application of the ele-
vatory force in the lower portion of the elevated mass, we must
necessarily conclude, that some relation must exist between
the causes which have produced the jointed structure, and the
action of the elevatory force; 7. e. between the action of a force
extraneous to the mass, and that internal molecular action, to
which it would seem absolutely necessary to refer the formation
of joints in the undisturbed mass. ‘To assert such relation to
be physically impossible, would, in the present state of our
knowledge, perhaps, be absurd; but it does appear to me that
the difficulty of conceiving it is so great as to form a most se-
rious, if not a fatal objection, to any theory in which it should
be involved as a necessary consequence. To avoid this ob-
jection, we might proceed on the hypothesis, that the lines or
axes of elevation have been principally determined by the lines
of less resistance along the joints, rather than as above sup-
posed; and such might be the case, if the principal line of
action of the elevatory force* should not deviate materially
from either of the two directions at right angles to each other
in which we are assuming joints to exist. If, however, that
principal line should approximate to an angle of 45° with these
rectangular directions, and should be of considerable length,
the hypothesis would be, [ conceive, altogether inadmissible.
Supposing then the accurate coincidence of the directions
of joints and those of fracture to be hereafter established, it
would appear that the hypothesis of the laws discoverable in
lines of fracture being generally due to the prior existence of
some regular structure in the undisturbed mass, would still
involve serious difficulties, on account of the relations existing
so generally between the lines of fracture and the configuration
of the elevated mass, for which, with the above hypothesis, it

* It must be recollected that we can only judge of the superficial form
and dimensions of the mass to which the elevatory force has been applied,
by those of the actual elevations. These appear unquestionably, I conceive,
to justify the notion of sufficiently determinate lines of action of the ele-
vatory force, at least in a sufficient number of instances to give due weight
to the argument in the text.

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 361

seems almost impossible to conceive any efficient physical
cause. On the other hand (still supposing the coincidence of
the directions of joints and of lines of fracture), if we assume
the formation of joints to have been posterior to the elevation
of the mass, this coincidence will still remain to be accounted
for. Our ignorance, however, of the process by which this
structure may have been superinduced, will not at present
allow us to do this. The fact must continue to offer a theo-
retical difficulty, but one, I conceive, very different in its
nature to that above stated, since it would appear, I think,
probable that, taking a portion of the elevated mass bounded
by adjoining fissures, the position of the joints subsequently
formed in it should have some relations to the boundaries of
that portion. The fact, therefore, of the coincidence (or rather
parallelism) of direction above mentioned, while it presents a
difficulty, does not seem to offer any @ priori objection to the
theory which involves it. It is proper, however, to observe
that though it should appear, for the reasons now stated, that
a preference may generally be due to the theory which would
assign the production of fissures to the elevatory force alone,
we should by no means be justified in the rejection in every
instance of that which attributes the directions of those fissures
to the previous structure of the mass, and especially in those
cases in which we fail to recognise distinct lines of elevation,
or the usual relations between them and the lines of dislo-
cation. And here it may be remarked as a striking fact, that
the only mining district in this country in which there is any
difficulty (as far as I have yet ascertained) in tracing these
relations, is that in which, for independent reasons, it appears
most necessary to recognise the influence ofa previously veined
or jointed structure on the directions of its dislocations. I
allude to the mining district of Cornwall.

In the above reasoning I have assumed the accurate coin-
cidence of the directions of joints and of lines of fracture, and
it is important to observe that this accuracy of coincidence is
essential to the theory which would assign the latter phzeno-
mena to the prior existence of the former. A difference of a
few degrees in the angular positions of the above lines would,
if iehats established, be fatal to this theory, because, as I have
already explained, although a fissure produced by an eleva-
tory force would cross a line of less resistance under a certain
condition, without change of direction, that condition cannot
be generally satisfied when the angle between the fissure and
line of less resistance is small, and in such case the fissure will
be propagated exactly along the latter line. Observations on
this point would therefore demand great care and accuracy.

Third Series. Vol. 8. No. 48. May 1836. 20

362 Mr. Hopkins’s Abstract of his Memoir on Physical Geology.

It is also important to remark, that the accurate coincidence
above spoken of will require two coexisting systems of joints
to be at right angles to each other, since such is the law recog-
nised in lines of dislocation. Observation, however, so far as
it has proceeded, appears in many instances, I believe, to con-
tradict this law in the directions of joints. Should any other
laws be established hereafter, or very frequent deviations from
the one just mentioned, it will probably be found necessary to
abandon altogether the notion that lines of dislocation have
been principally determined by the directions of joints, rather -
than by the mode of action of the elevatory force.

The theory which it has been the object of my memoir to
develope, enables us to account for nearly all the more im-
portant phenomena of elevation; but before we finally decide
on its relative claims to our adoption, we are manifestly called
upon to remove as far as possible, by accurate observation,
the uncertainty which still remains respecting the possible in-
fluence of a jointed structure in producing what I have termed
the primary phzenomena of elevation. ‘These speculations are
thrown out with the hope of indicating some of the more cri-
tical points of inquiry on which the ultimate determination of
this question must turn, and which are generally best indicated
in such cases by theoretical discussion. The necessary re-
lations which I have shown must exist, according to one of
these theories, between the directions of dislocation and the
general, and in some cases local, conformation of the elevated
mass, will probably do much towards enabling us ultimately
to decide between them; and it is therefore of the first im-
portance that the observer who may hereafter wish to eluci-
date this subject, should remark these relations as carefully as
those which may exist between the dislocations themselves, or
the joints with which they may be associated *.

We may here observe, that the only difference between the
two theories we have considered, consists in the cause which
they assign for what I have termed, with reference to the

* It would be important, as before intimated, to observe the directions
of joints in a conical elevation with lines of dislocation diverging from its
vertex. [am not aware that the existence of a similarly diverging system
of joints has ever been suspected. It would also be highly desirable to ob-
serve whether there be any continuity in the joints of two contiguous but
distinct formations, and particularly when one formation is primary and the
other. sedimentary. The perfect continuity of the veins in Cornwall, in
passing from the killas to the granite, forms a curious feature in the geology
of that district, if we are to regard the former as a sedimentary deposit.
In such case, it would clearly demonstrate that the regular structure to
which, I conceive, many of those veins must be referred, was superinduced

in that district after the great dislocations which must have accompanied
the injection of the granite.

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. $63

theory with which I have been more particularly occupied,
primary phenomena. The secondary phenomena of faults,
mineral veins, anticlinal lines, valleys, &c., will be deducible
from the primary ones just in the same manner in both theo-
ries, so that nearly the whole of the investigations contained
in the second section of my memoir will be equally applicable
to both these theories.

In that section I have entered, as before intimated, with
considerable detail into an examination of the secondary phe-
nomena of elevation, such as anticlinal lines, longitudinal and
transverse valleys, ejected and injected horizontal beds of trap,
veins of trap and granite; and also the different phenomena
of mineral veins, such as the throw and depth of a vein, the
comparative widths of the best bearing veins and cross courses,
and the shifts or heaves so frequently recognised at the inter-
sections of veins. I have also stated reasons for concluding
that the fissures of mineral veins must have been filled by some
process of infiltration or segregation (which I profess not further
to define) from the surrounding mass; and here, viewing this
point with reference to the subject of joints, I would further
observe, that the formation of a vein (by which is here meant
the matter contained in the fissure) might take place along an
open joint, exactly in the same manner as along a fissure pro-
duced by any other means. If, therefore, we find veins (such
as those before alluded to in Cornwall) which cannot be sup-
posed to originate in the dislocating effects of an elevatory
force, we should carefully examine how far the directions of
these veins appear to coincide with those of the leading joints.
From a hasty inspection of the Cornish veins, I have a strong
impression that this coincidence will be found to exist in that
district. It would be important to ascértain this fact by care-
ful and detailed observation; for, should it be established, it
will immediately destroy the hypothesis of the contemporaneous
formation of such veins as a necessary alternative, and at least
remove one inconceivable process from the speculations of
geologists, more especially with respect to those who may at
once be disposed to allow this mode of formation of the Corn-
ish veins, while they contend for the fact of the mass in which
they are found being a sedimentary deposit. The difficulty
of the theory of all similar veins will be reduced by my hy-
pothesis to that of the formation of joints, a process hard
enough to conceive, but which has its analogy in that of cry-
stallization, and must of necessity be recognised. ‘The pro-
cess of contemporaneous formation of veins, without the pre-
vious formation of fissures as receptacles for the segregated or
infiltrated matter, appears to me inconceivable in itself, and

202:

$64 Mr. Hopkins’s Abstract of his Memoir on Physical Geology

unsupported by any analogies drawn from the known opera-
tions of nature.

VI. There is another point on which I have touched inci-
dentally in the conclusion of my memoir—the application of
the principles already explained to the theory of Elie de Beau-
mont, respecting the parallelism of mountain-chains of con-
temporaneous elevation. I have before stated, that in what-
ever manner we may conceive an elevatory force to be pro-
duced, there seems no reason why we should not suppose it,
in some cases, to have acted at a much greater depth than in
others. Now I have already explained (p. 278) the reason
for concluding that the formation of a system of fissures, ac-
cording to our theory, must be simultaneous; and also how
the simultaneous formation is facilitated by the circumstance
of time being necessary for the transmission of the relaxation
of the mass produced by the opening of a fissure. From that
explanation it will easily be seen, that if a number of fissures
commence simultaneously in the lower portion * of an elevated
mass of great thickness, and great superficial extent, it is most
probable that those only will reach the upper surface which
are remote from each other. These fissures will be large,
and all the phenomena resulting from them may be expected
to be on a proportionate scale. Anticlinal lines + will almost
necessarily be formed along them; and thus it is as easy to
account for two parallel mountain ranges, as for two neigh-
bouring anticlinal lines on a scale of comparatively small mag-
nitude; and our theory will thus assign a physical cause for
the Jaw of parallelism in mountain chains of contemporaneous
elevation, as contended for by M. Elie de Beaumont, if, at
least, the application of that geologist’s theory be restricted
within certain limits. I have no intention, however, of now
insisting on this extensive action of the physical cause I have
been considering ; but I would observe, that the extent of this
action can only be determined by that of those portions of the
earth’s surface throughout which the laws of observed phzeno-
mena may be continuous, and in accordance with our theore-
tical deductions.

To persons not habituated to the investigation of the accu-
rate relations between mechanical causes and their effects,
much of the previous reasoning may appear too refined to be
applicable to our subject; but it must always be recollected,
that this reasoning is immediately applied to hypothetical pro-

* Lhave shown that these fissures must generally commence in some
lower portion of the elevated mass. See Memoir, p. 43.
+ See Memoir, p. 51.

Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 365

blems, to which it is strictly applicable, and which are chosen
so as to bear the closest analogy to the corresponding ones
which nature presents to us; and it is simply on the strictness
of this analogy that we are called upon to decide, in judging
of the admissibility of our mode of investigation. It is im-
portant to have a clear conception of this principle, on which
the application of strict analysis to the problems of nature
must always be made. In fact, this is the principle on which
every one must tacitly (sometimes perhaps unconsciously) pro-
ceed, in forming a distinct idea of the necessary relations be-
tween any physical cause acting under complicated conditions,
and its remoter consequences. We must form our conclu-
sions from the consideration of some comparatively simple
but strictly analogous case, and apply them to the actual one,
with such limitations as circumstances may require. The
advantage which the mathematician possesses, consists in this
—that the standard case to which he refers his more complex
problem, is a definite one, from which he has means of de-
ducing his results free from that uncertainty which necessarily
attends other modes of investigation. It is a standard case of
this kind, which I have endeavoured to supply for geological
theories of elevation; nor am I without hopes, that the attempt
may at least so far succeed as to remove some of that inde-
finiteness on this subject, by which the earlier speculations in
every science must almost necessarily be characterized. More
particularly, perhaps, may this be asserted of geology, which,
notwithstanding the rapidity of its growth, is yet hardly strong
enough to emerge from the cloudiness in which its phraseo-
logy alone, with reference to the phenomena of elevation, by
addressing itself more to the imagination than the judgement
of the student, has sometimes been sufficient to involve it. An
impression has thus been too frequently created, that little
hope exists of elevating the science to any rank among the
stricter physical sciences. Such a notion, however, appears
to me most fatal to its healthy progress. The author of the
Principles of Geology, whatever may be thought of some of
his theoretical views, must be allowed by all to have set us an
example well calculated to improve in this respect the tone of
' geological speculation, in as much as he has boldly grappled
with the difficulties of his problems in detail, and not been
content to meet them with indeterminate generalities. In
these investigations I have endeavoured to act upon the same
principle, as the only one on which, if we are to speculate at
all, we can speculate with safety; and if, perchance, a some-
what vagué and misty sublimity which has appertained to this

366 Sir P, G. Egerton’s Catalogue of Fossil Fish

branch of the science should thus be diminished, ample com-
pensation will be made if we should in return confer upon it
a portion, however small, of the more naked dignity of de-
monstrative truth.

St. Peter’s College, Jan. 7, 1836.

LXVIII. Catalogue of Fossil Fish in the Collections of Lord
Cole and Sir Philip Grey Egerton, arranged alphabetically ;
with References to the Localities, Geological Positions, and

| published Descriptions of the Species. By Sir Puivip DE
Matpas Grey Ecerton, M.P., F.R.S., £.G.S.

To the Editors of the Philosophical Maguzine and Journal.

GENTLEMEN,

Be following “ Catalogue of Fossil Fish” was printed for

private distribution, but I am induced tosolicit its insertion
in your widely-circulated Journal in the hopes that it may
prove of interest beyond the immediate pale of my personal
friends and acquaintance ;—to the geological adept, as exhi-
biting in a tabular form the stratigraphical position of two
hundred and twenty-seven species,—to the student in fossil
ichthyology, as affording a clue to the depositories of many
new and rare specimens destined to appear in the forth-
coming numbers of Dr. Agassiz’s ‘ Recherches sur les Poissons
Fossiles.”

To the discriminating eye and classic orthography of that
distinguished naturalist I am indebted for the diagnosis and
nomenclature of the new genera and species enumerated in the
Catalogue, as well as for the identification of such as were
raleady known. I remain, Gentlemen, yours, &c.

Oulton Park, Feb. 6, 1836. Puitie Grey Ecerton.

The letter c ore prefixed to a species denotes the Collection to which it belongs
when not common to both.

GENUS AND SPECIES. STRATA AND LOCALITIES.
Acanthoderma spinosum ..... Engi, canton Glaris.
Acanus oblongus* .......... Engi, canton Glaris.

c new species not yet named Engi, canton Glaris.
gE Acipenser, new species not yet
nMed Fe 6 ..... (Lias.) Lyme Regis.
Acrodus nobilis ..........-- (Lias.) Lyme Regis.
c gibberulus .,.... .. (Lias.) Lyme Regis.

* This genus is found in the Planer Kalk.

LP LAr Fw

9) s and Lord Cole’s Collections. 376. 6)
: IES. STRATA AND LOCALITIES.
$ wEPe ies. (Lias.) Brunswick.
dé tti .w.gle... (Lias.) Brunswick.
whe 6 med........ (Lias.) Lyme Regis.
» erygius.
By q BG MS. (Coal Formation.) Lebach.
@\3 ss. Agass. vol.
Re We ose (Coal Formation.) Lebach.
_— , Agass.vol.ii.
ee Gee (Coal Formation.) Lebach.
& ¢ oterus. Agass.
Si: hind A Franc aPt ics ote (Coal Formation.) Lebach.
5 j, @eine +.) Engi, canton Glaris.
= . lanum...... Engi, canton Glaris.
pleurum »... Engi, canton Glaris.
> ATM re) 01a Engi, canton Glaris.
= » RS tats UR Engi, canton Glaris.
z 7 icutirostris .. (Oolite.) Solenhofen.
¢ bularis.w.... (Oolite.) Solenhofen.
~ miradiatus r;. (Oolite.) Stonesfield.
3 ssimus w..... (Kimmeridge Clay.) Shotover Hill.
- sphala .....% (Tertiary Beds.) Monte Bolca.
° itosteus #1... (Oolite.) Stonesfield.
- .™ Geology of
SU (Chalk.) Sussex.
= salis. Agass.
LE Le ee (Tertiary Beds.) Monte Bolca.
2 serratus t.... (Tertiary Beds.) Malta.
§ odon. Agass.
aj. VM. Stee .. (Tertiary Beds.) Malta.
— CEUSI Sy 5.-)0\0 0/0 (Tertiary Beds.) Malta.
e~ (AGO Wise 3.4 North America.
z lotis.» <Agass,
Be ela aiateateione « North America.
OM Bt ae North America.
BEM Pie <a "<0 North America.
c ———— subserratus n..... (London Clay.) Sheppey.
Caturust macrodus »........ (Oolite.) Solenhofen.
microchirus .%....... (Oolite.) Solenhofen.
MAK UMMIS(c!s Wo 5 als oes (Oolite.) Solenhofen.
c pachyurus .».......- (Oolite.) Solenhofen.
x Chimera{ Egertonii ........ (Kimmeridge Clay.) Shotover Hill.
Clupea Beurardi.\.......... (Tertiary Beds.) Mount Lebanon.
DCVIS... Per 2. 52 2. ves Engi, canton Glaris.
megaptera.......... Engi, canton Glaris.
Scheuchzeri,
a doubtful species. —Agass. Engi, canton Glaris.

* Zeus Lewesiensis, Mantell.
+ Originally named Ureus by Agassiz.

+ Discovered and described by Dr. Buckland, [See our present volume,
pp. 4, 5.—Enprr. }

366 Sir P, G. Egerton’s Catalogue of Foss

branch of the science should thus be diminish
pensation will be made if we should in retur
a portion, however small, of the more nake
monstrative truth.

St. Peter’s College, Jan. 7, 1836.

LXVIII. Catalogue of Fossil Fish in the |
Cole and Sir Philip Grey Egerton, arran
with References to the Localities, Geolo,

; published Descriptions of the Species.
Matpas Grey Ecerron, M.P., F.R.S.

To the Editors of the Philosophical Ma;

GENTLEMEN,
‘THE following “ Catalogue of Fossil

private distribution, but I am induce
in your widely-circulated Journal in
prove of interest beyond the immedia’
friends and acquaintance ;—to the gec
biting in a tabular form the stratigr
hundred and twenty-seven species,—
ichthyology, as affording a clue to tl
new and rare specimens destined ‘
coming numbers of Dr. Agassiz’s “ Rx
Fossiles.”
To the discriminating eye and cl
distinguished naturalist I am indel
nomenclature of the new genera anc
Catalogue, as well as for the ider.
raleady known. I remain, Gentlemen, you~,
Oulton Park, Feb. 6, 1836. Puitie Grey Ecrerron.

The letter c or x prefixed to a species denotes the Collection to which it belongs
when not common to both.

GENUS AND SPECIES. STRATA AND LOCALITIES.
Acanthoderma spinosum ..... Engi, canton Glaris.
Acanus oblongus* .........- Engi, canton Glaris.

c new species not yet named Engi, canton Glaris.
gE Acipenser, new species not yet
named ......ee+-+e-ee--~ (Lias.) Lyme Regis.
Acrodus nobilis ...... ras (Lias.) Lyme Regis.
c gibberulus .,...... (Lias.) Lyme Regis.

* This genus is found in the Planer Kalk.

in his and Lord Cole’s Collections.

GENUS AND SPECIES.

c Acrodus Bronnii. %.5f......
Cc Guilliardetti .wiel....
———— not yetnamed...i....

Amblypterus eupterygius.
Agass. vol. ii. p. 36
lateralis. Agass. vol.

——

ii. p. 39

latus. Agass.vol.ii.
macropterus. Agass.
vol. u. p. 31
Anenchelum dorsale. »
Glarisianum ......
heteropleurum »...
isopleurum .y.....
TAU nyees gota fhe -
Aspidorhynchus acutirostris
mandibularis.w....
Asteracanthus semiradiatus ¥ .
ornatissimus »....

Atherina macrocephala ......
Belonostomus leptosteus m...

Beryx ornatus *.* Geology of

Susser 9s): . Sees ATA eh
c Carangopsis dorsalis. Agass
VOL Nppln Sa paeier. yas a ited

Carcharias grossiserratus t...
megalodon.» Agass.

376 36)

STRATA AND LOCALITIES.
(Lias.) Brunswick.
(Lias.) Brunswick.
(Lias.) Lyme Regis.

(Coal Formation.) Lebach.

(Coal Formation.) Lebach.
(Coal Formation.) Lebach.

(Coal Formation.) Lebach.

Engi, canton Glaris.
Engi, canton Glaris.
Engi, canton Glaris.
Engi, canton Glaris.
Engi, canton Glaris.

.. (Oolite.) Solenhofen.

(Oolite.) Solenhofen.

(Oolite.) Stonesfield.
(Kimmeridge Clay.) Shotover Hill.
(Tertiary Beds.) Monte Bolca.
(Oolite.) Stonesfield.

(Chalk.) Sussex.

(Tertiary Beds.) Monte Bolea.
(Tertiary Beds.) Malta.
(Tertiary Beds.) Malta.
(Tertiary Beds.) Malta.

North America.

North America.
North America.
North America.

VO: Sep 29IANs).). Lt ae
productus h.......
Cc macrodon w.......
c megalotis.». Agass,
mola plies. . Connie).
minor’ ow. se Ps...
—— polygyrus m......
c

&

subserratus »..... (London Clay.) Sheppey.
Caturust macrodus »........ (Oolite.) Solenhofen.
microchirus 4....... (Oolite.) Solenhofen.

AVLERATNVS ST m's'< avs) « eres (Oolite.) Solenhofen.
pachyurus .»........ (Oolite.) Solenhofen.

Chimera} Egertonii ........ (Kimmeridge Clay.) Shotover Hill.
Clupea Beurardi.1.......... (Tertiary Beds.) Mount Lebanon.
ICV IBAA 50. i5:c)nte asap Engi, canton Glaris.
megaptera.......... Engi, canton Glaris.

Scheuchzeri,

a doubtful species. —Agass. Engi, canton Glaris.

* Zeus Lewesiensis, Mantell.
+ Originally named Ureus by Agassiz.
} Discovered and described by Dr. Buckland, [See our present volume,

pp. 4, 5.—Epir. |

368 Sir P. G. Egerton’s Catalogue of Fossil Fish

GENUS AND SPECIES. STRATA AND LOCALITIES.
Clupea catopygoptera..... . (Tertiary Beds.) Monte Bolca.
COMMIS Bedicitte: «, Lafetaiaie (Tertiary Beds.) Sicily.
c Cobitis cephalotes.» Agass. vol.
Vis Jil. eatnee ohatainid erate setae (Tertiary Beds.) G&ningen.
c Ceelacanthus, new species ..... (Magnes. Limest.) East Thickley.
Cottus: brevis iy cca. 5 i .cieiee (Tertiary Beds.) Q&ningen.

x Ctenacanthus tenuistriatus.y.. (Mountain Limestone.) Bristol.
c Cybium macropomum, y...... (London Clay.) Sheppey.

Cyclurus crassus. iz... ....0 Engi, canton Glaris.
nemopterus iw . : Engi, canton Glaris.
Dapedius Colei. Agass. vol. 5.
Dp. LOR EE Naar es 61.3 (Lias.) Lyme Regis.
granulatus, § Agass.
volsai eas AOL ce etete janis (Lias.) Lyme Regis.
politus *. Geol.
Trans. 2nd series, vol.i.Agass.
Vol..11. (Pp; MBvecisea'. «is sisietn s (Lias.) Lyme Regis.
— punctatus. Agass.
VOL? Uap 1 LOD Les... Gistewsteys & (Lias.) Lyme Regis.
Dercetis elongatus t. Geol. of
POLLS SORicteiers-cueieteseiain so) eice.e (Chalk.) Sussex.

Dipterusmacrolepidotus}. Geol.
Trans. 2nd series, vol. iii.

Agass. vol. ii. p.114,...... (Schist.) Caithness.
Ductor leptosomus. Agass. vol.
Men PLeOL es lei steperetareis Salat shale (Tertiary Beds.) Monte Bolca.
Esox lepidotus n........... (Tertiary Beds.) C&ningen.
c Eugnathus chirotes......... (Lias.) Lyme Regis.
; ornatus .n.......- (Lias.) Lyme Regis.
x Fistularia magnifica .w....... Engi, canton Glaris.
tenuirostris ....... (Tertiary Beds.) Monte Bolca.
Galeus aduncus." Agass. vol. iii,
PL. 2G Aeharctahe Wide Ha ieraie's 5 (Molasse.) Switzerland.
SOrVAGUS . A Wists wes « (Molasse.) Switzerland.
c pristodontus §. ».
Agass. vol. iii. pl. 26. Geol.
of Sussex, pl. 32......... « (Chalk.) | Maéstricht.
not yet named...... (Chalk.) Sussex.
Gasterocnemus rhombeus. —
Agass. vol. v. p. 20........ (Tertiary Beds.) Monte Bolca.
Gyrolepis Albertii. Agass. vol. ii.
Pe Paitin Cop ABoclpiniewin gs (Muschel Kalk.) Bayreuth.
—__—— tenuistriatus. Agass.
VOLIGED. BRAGS eek ote. (Muschel Kalk.) Bayreuth.
Hemipristis serra. Agass. vol.
LV SpE LA eee alps tyb) 1000: (Molasse.) Switzerland.
* De la Beche. + Murena Lewesiensis, Mantell,

t This includes the four species of Sedgwick and Murchison.
§ Also found in the chalk of Sussex.

bo}

‘in his and Lord Cole’s Collections. 369

GENUS AND SPECIES. STRATA AND LOCALITIES.
Holocentrum pygeum. Agass.
OLE ple? 6 eT ET I (Tertiary Beds.) Monte Bolca.
Hybodus curtus*.W........ (Lias.) Lyme Regis.
———— incurvus..¥....... (Lias.) Lyme Regis.
— grossispinus....... (Lias.) Lyme Regis.
——- ornatus #...... .-. (Lias.) Lyme Regis.
————- reticulatus *....... (Lias.) Lyme Regis.
igen MPL SIS : (Lias.) Old Passage, Bristol.
marginalis m....... Lias.) Keynsham.
Jott, Iron Sand & Oolite.) Tilgate and
grossiconus \...... i Stonesfield, Loess
——_- |polyprion: Yi... 03.5; Oolite.) Stonesfield.
dorsalis w......... ¢ al Stonesfield.
— aeutuss mL L ORS (Kimmeridge Clay.) Shotover Hill.
=" plicatilisnnes oreo: (Muschel Kalk.)
new species not yet
nied AB OEIC XS (Oolite.) Purbeck.
Isurus macrurus .i......... Engi, canton Glaris.
Labrax-schizarus (R202 0r% 3 (Tertiary Beds.) Monte Bolca.
Lamna acuminata t.’* Geol. of
Sassen: pl: SEIS. aL (Chalk,) Sussex.
MantelliinGeol. of Sus-
Serr pl Sacre. ere 8) (Chalk.) Sussex.
appendiculata/*Geol. of
USMS BD) Ola toe. eae (Chalk.) Sussex and Maéstricht.
contortidens a ...... (Molasse.) _ Switzerland.
———— Seuspidatar tes o57).%.: (Molasse.) Switzerland.
———— dentienlatart..)05) } (Molasse.) Switzerland.
—— hastalist m......... (Molasse.) Switzerland.
——— quadrans......... (Molasse.) Switzerland.
—— obliqua ® 2.2.0... London Clay.) Sheppey.
————' plicata mi. eo London eres Sheppey.
——- trigonodus. W....... Tor oem Malta.
— — xiphodon.......... Tertiary Beds.) Malta.
new species not yet
SUMO O. AN aft 3S Molasse.) Switzerland.
Lebias crassicaudus ->....... Tertiary Beds.) Sinigaglia.
Leptacanthus semistriatus b. .. (Oolite.) Stonesfield.

Lichia prisca. Agass. vol. v.

pit iar et 21, Be Tertiary Beds.) Monte Bolca.
Lepidotus fimbriatus ........ trae) Lyme Regis.
Fittonii§. . <Agass.
VOL Ps OO, Ci Ben. snsyetse (Tilgate Beds.) Tilgate Forest.
Mantellii§. Agass.
TOR, Ho PLBU esecGMlS } as (Tilgate Beds.) Tilgate Forest.

* This Ichthyodorulite probably belongs to H. reticulatus.
+ Also from Quedlinburg. + Also from Malta.
§ Lepisosteus Fittonii, antell.

Third Sevies. Vol. 8. No, 48. May 1836, 2P

370 Sir P. G. Egerton’s Catalogue of Fossil Fish

GENUS AND SPECIES. STRATA AND LOCALITIES.
s Lepidotus maximus. !*..... (Oolite.) Stonesfield.
new species not yet
named ...+.++++++++++++.+ (Oolite.) Stonesfield.
—__—_——— minor. Agass. vol.
ii. ple SCH ASH eh} (Oolite.) Portland.
— notopterus. # Agass.
Vol 1. pl B4 Schick, (Oolite.) Solenhofen.
c new species not yet
Rimed -.caeN Ke: Les Kimmeridge Clay.) Boulogue.
Leptolepis Bronnii.......... (ht Lyme Regis.
caudalis..... ..... (Lias.) “Lyme Regis.
c contractus,....... Oolite.) Solenhofen.
nbs... c) Oolite.) Solenhofen.
EV ISMOIEL Reese.» (Oolite.) Solenhofen.
sprattiformis ,,.... (Oolite.) Solenhofen.
c Leuciscus gracilis. ........ (Tertiary Beds.) _Wurtemberg.
CTS Ws, tsi .. (Papier Kohl.) Rhine.
papyraceus. » Agass.
WAL MepIS SG -cks aay L } (Papier Kohl.) Rhine.
CEningensis.wAgass.
vol. v. pl. 57—58 ........-. (Tertiary Beds.) C&ningen.

Q

onl

Macropoma Mantellii *.’* Geol.

of Sussex, p. 239 ......... (Chalk.) Sussex.
Mallotus villosus fossilis? .... Greenlandt.
Megalichthys Hibbertii. Trans.

Royal Soc. Edin. v.13 .... (Coal Formation.) North Stafford.
Megalops priscus J ........ (London Clay.) Sheppey.
Microdon hexagonus ........ Oolite.) Solenhofen.

new species not yet
MUTCD ONG ONT Ses 4 hls oak} ee Stonesfield.
Mugil princeps -®&.....-...- Tertiary Beds.) Aix.
Myliobates angustus..2...... (London eee Sheppey.
—_——_—. subarcuatus.n...... eee Clay.) Sheppey.
Studeris .mcic.ie. os Molasse.) Switzerland.
: Myriacanthus paradoxus .%... (Lias.) Lyme Regis.

Myripristis homopterygius.... (Tertiary Beds.) _ Monte Bolca,
Notidanus} primigenius. Agass.

wol..411 Spb 27 0c3%.36 pe eh (Molasse.) Switzerland.
Odontaspis rhaphiodon§ w..... (Chalk.) Maéstricht.
Ophiopsis dorsalis ......... (Oolite.) Purbeck.
Osmeroides Mantellii ||... Geol.
of Sussex, p: 235 .......-. (Chalk.) Sussex.
Osteolepis arenatus. Agass. vol.
Si, Pe pias». ankaagsss 52 (Coal Series.) Gamrie.
Palzoniscus comptus. Agass.vol. {(Magnesian Limestone.) East
LL, be OD Maateestas meee asce, «= Thickley.

* Amia Lewesiensis, Mantell.

+ [See Lond. and Edinb. Phil. Mag., vol. v. p. 461.—En1r.]

+ This genus is also found in the chalk of Sussex.

§ Also from the chalk of Sussex. || Salmo Lewesiensis, Mantell.

in his and Lord, Cole’s Collections. 371

GENUS AND SPECIES. STRATA AND LOCALITIES.

Palzoniscus elegans. Agass. vol. {(Magnesian Limestone.) East

The Be 9B, ARGS AE. deatete 3 } Thickley.
c longissimus. <Agass. {(Magnesian Limestone.) East
wol. ais px VAD n gis w. heeday-fe ss > Thickley.
Freieslebeni. Agass.
Vol, Tis piGBeehe <h12\es 2} (Kupfer Schiefer.) Eisleben.
magnus. Agass. vol.
By Pat Se tA scala aS > (Kupfer Schiefer.) Eisleben.
ea eer toll) esha) sk (Coal Shale.) North Stafford.
Blainyillei. Agass.
OLMIS GAS oe eh aioe, ces 2 ayer < Muse, near Autun.
Duvernoy. Agass.
VOL Bp Ao. GPS SA. (Coal Formation.) Zweibriicken.
macropomus. Agass.
70 Mi 8 a a as (Zechstein.) Ilmenau.

c Paleorhynchum Colei........ » Engi, canton Glaris.
Egertonil......... » Engi, canton Glaris.
Glarisianum ...... , Engi, canton Glaris.

— datunit sR Stee Engi, canton Glaris.
MCAMMYK.-/'5 20> » Engi, canton Glaris.
microspondylum... , Engi, canton Glaris.

———- longirostris ....... » Engi, canton Glaris.

Palimphyes brevis. ). Agass. vol.

Tie TAO icra iieloss: dpte’ ssi acs ave Engi, canton Glaris.
longus. Agass. vol.
REN S28 RES ES ee Engi, canton Glaris.

Pholidophorus Bechei. Geol.
Trans. 2nd series, vol. i..... (Lias.) Lyme Regis.

latiusculus........ Tyrol

HAAS 5 a: ©: Hotere ian Lyme Regis.

onychius ....... (Lias.) Lyme Regis.
——+—_=-)Jatimanus Wi...) (Oolite.) Solenhofen.

E ————— radiatopunctatusi!. (Oolite.) Solenhofen.

c ———— taxis .%.......... Oolite.) Solenhofen.
—_——— ureoides v:....... Oolite.) Solenhofen.
Placodon gigas ..w........-- (Muschel py Bayreuth.

E — Minsteri »........ (Muschel Kalk.) Bayreuth.

c Platysomus gibbosus, ~ Agass.

VOI. 1). 164 HOS 2.50.5. (Kupfer Schiefer.) Mansfeld.

x Pleiocnemus macrospondylus. ') Engi, canton Glaris.
Pleuracanthus serratus...“ ... Engi, canton Glaris.
Psammodus magnus. ...... Saas Stonesfield.

CenMs 67 Views. es Oolite.) Stonesfield.
reticulatus. »...... hee Clay.) Shotover Hill.
porosus ..... 2.66 Mountain Limestone.) Bristol.

x Pterygocephalus paradoxus ... (Tertiary Beds.) Monte Bolea.

c Ptycholepis Bollensis ....... Lias,) Lyme Regis.
Ptychodus altior.),Geol. of Sus-

$08, DOM g sss esccet ses (Chatk ) Sussex.

P2

372

Sir P. G. Egerton’s Catalogue of Fossil Fish.

GENUS AND SPECIES. STRATA AND LOCALITIES.

Ptychodus decurrens.” Geol. of

Susser, pl. 32:5. iy hee we Be (Chalk.). Sussex.
— latissimus. 1. Geol. of
Sussem,. pl. 32.29 Nels | (Chalk.) Sussex.
mammillaris. ~ Geol.
of Susser, pl. 832 ......... (Chalk.) Sussex.
— polygyrus.y. Geol. of
Sussex; pls 82 sgh ak Chalk.) Sussex.
Pyenodus Bucklandii.\...... ( Oolite } Stonesfield.
PAR V IDE ena) hime oi (Oolite.) Stonesfield.
c new species not yet
MINED rate fe ss eos) = Oolite.) Stonesfield.
microdon\..). ...). eriloats Beds.) Tilgate Forest.
a es Jura.
c Pygzeus, new species not yet
ROME TT. Seer sie = sk Tertiary Beds.) Monte Bolea.
Semionotus rhombifer .»..... (Lias.) Lyme Regis.

— new species not yet

meme PBI. BOT sk (Bit. Schist.) Seefeld, Tyrol.
Smerdis micracanthus. <Agass.
VOLSaV ep! SoH: OPS. ire (Tertiary mae Monte Bolca.
PANMGUS ist. 2G ww we se Tertiary Beds.) Aix.
Spheradus ISAS. 66 « sae sos - tonite} Stonesfield.
c new species not yet
CET AS A aR RES SO IE Jura. :
c Sparnodus altivelis.......... (Tertiary Beds.) Monte Bolca.
E macrophthalmus .. (Tertiary Beds.) Monte Bolea.
E ————— micracanthus...... (Tertiary Bet Monte Bolca.
ce Sphyrena gracilis .......... Tertiary Beds.) Monte Bolca.
c Spinacorhinus polyspondylus*r-(Lias:) Lyme Regis.
c Tetragonolepisconfluens. Agass.

VOL HO Pe TO? tele. Lae (Lias.) . Lyme Regis... —
heteroderma ...... (Lias.) . Lyme Regis...
eaghn'.. fe). en Lyme Regis.
pholidotus ........ Lias.) . Lyme Regis.

c ————— pustulatus........ trian Lyme Regis.
—— speciosus. Agass.vol. . ...

RE a AS aE A Sa A Lias.) Lyme Regis.

E ————— radiatus.......... Lias.) Lyme Regis.
Tetrapterus priscus &........ (Liss) Clay.) Sheppey.

c Thrissops salmoneus
Tinca furcata.

Agass. vol. v.

(Oolite,) Solenhofen.

Pl SP). eae). (Tertiary Beds.) C&ningen.
E Vomer longispinus. Agass. vol.
Vepies LNW eae. (Tertiary Beds.) Monte Bolca.

Specimens undetermined.
New genus allied to Palimphyes..

Engi, canton Glaris.

* Squaloraia dolichognathus, Dr. Riley. [See Lond. and Edinb. Phil.

Mag,, vol. iii. p. 369.—Enir. }

Mr. Rumker’s Method of reducing Lunar Observations. 373

GENUS AND SPECIES. STRATA AND LOCALITIES.

New genus allied to Scopelus ... Engi, canton Glaris.

E Placoid fish not yet named.... ae Shale.) North Stafford.

E Placoid fish not yet named.... (Coal Shale.) North Stafford.

E Placoid fish not yet named.... (Coal Shale.) North Stafford.

E Placoid fish not yet named.... (Coal Pier North Stafford.
Scomberoid not yet named ... (London Clay.) Sheppey.

c Ten species not yet named.... (London Clay.) Sheppey.

c New genus not yet named.... (Tertiary Beds.) QEningen.

LXIX. On a new Method of reducing Lunar Observations
Jor the Determination of the Longitude. By Cuaries
RumkeEr, Esq., F.R.A.S.*

To Lieut.-General Sir Thomas Macdougall Brisbane, K.C.B.,
Pres. RS. E., F.R.S.L., F. Ast. S., §c.
Sir,
HE lively interest which you took in the determination of
the longitude by lunars, and the success which attended
your observations, animate me to submit the following me-
thod, admitting of greater accuracy when either altitude is
low, to your approval and patronage. Allow me to remind you
here, that already when I had the honour of accompanying
you on your passage to Australia, I had occasion to allude to
the necessity of a more strict method, suitable to the circum-
stances. ‘This subject has since been treated by a celebrated
astronomer. His method appears to me, however, not likely
to be generally adopted by seamen, and requires, moreover, a
particular ephemeris, which becomes useless on ordinary oc-
casions, when the usual methods answer every purpose.

I hope, therefore, that the following method, which re-
quires no other tables than the Nautical Almanac, and may,
according to circumstances, be computed with more or less
precision, will meet your approbation.

The object of the present lines is to correct the error com-
mitted in the usual methods of clearing the apparent di-
stance between sun and moon by taking out the refraction
for the central altitude of both bodies, whereas it is the re-
fraction for those points of their limbs, the distance of which is
actually measured, that should be used in the calculation.

As introduction, it may not be useless to remark, that the
usual methods of clearing the distance, supposing the alti-
tudes known from observation, can be classed into direct and
approximative ones. For thus, as all the former methods
are derived from the equation existing between the sides of

* Communicated by Sir Thomas M. Brisbane, K.C.B., &c.. A portion
of this paper was inserted in our Number for October last : this having re-
quired some corrections, we now give the Communication entire.

374 Mr. Rumker’s new Method of

the two triangles formed by the apparent zenith distances and
distance, and the true zenith distances and distance, and only
differ by slight variations in the manner of finding thence the
true distance, or side of the latter triangle opposite to the angle
at the zenith common to both triangles, the latter methods
unite all in computing in the apparent triangle the angle at
the sun and moon, and the sides adjacent thereto in two right-
angled triangles having for hypothenuses the corrections of
the sun’s and moon’s altitudes. These sides are the corre-
sponding corrections of the distance.

Let D designate the apparent distance of the centres, S and
M the above angles atthe sun and moon, e—7 the difference
between parallax and refraction or correction of altitude,
then is the true distance of centres = D + cosine S.(e—7)
+ cosine M (@!—7’) +a (e—7')? + (el —w)? + 4+.

The moon’s parallax being greater than her refraction, the
second correction becomes negative; and when one of the
angles is obtuse, its cosine takes the opposite sign. ‘The fun-
damental formula of all approximative methods is,

( sin k — sin H cos D ipso

cos H sin D ) g
Ee H-—sin 4 cos D

cos A sin D
where g and = refer to that altitude 2 or H which stands first
and by itself in the parenthesis. Lyons obtains by executing

the division,
D + (sin 2 sec H cosec D— tan H cot D) (e—7)
+ (sin Hsec 4 cosec D— tan h cot D) (e—7)+ +.

sin k—sin H cos D
If we make ( ent tustallk ) (y—7)

sin h—sin H cos D
Se tien

* 2cos$}(D+H+h) sin} (D+ H—A2)
=(1 Bh cos H. sin D ) (e—"),

we obtain the one part of Mendoza Rios’ approximative for-
mula to which the other is analogous; and by separating in
Lyons’s method the moon’s parallax from the refraction, thence
results the correction of the distance for the moon’s parallax
sin € alt. sin © alt.

only = hor. par. x [_sap~ ee ie i

which is identical in Elford’s, Thomson’s, and Lynn’s tables, is
found graphically by Kelly, and by Norie in his linear tables,
and which Thomson finds with his lunar scale; and it is only in

true distance = D +

) (—2") + + ty ots

reducing Lunar Observations. ~ 375

the manner of allowing for the refraction and the sun’s parallax
that the above authors differ ; all of whom, however, with the
exception of Lynn, have erred in using in the calculation the
apparent altitude, whereas the apparent altitude corrected for
refraction should have been used. On the same grounds the
usual tables exhibiting the moon’s correction by inspection,
including parallax and refraction, are erroneously computed.

By approximative methods are not to be understood me-
thods that admit of less accuracy, but such as approach the
truth by a series of which the last terms vanish, or, which
answers the same purpose, by a gradual substitution in the
calculation of terms found by a former approximation. The
approximative methods have, particularly to seamen, that ad-
vantage above the direct ones, that the trigonometrical calcu-
lation need only be executed to the nearest minute; and as
the correction of the distance never can exceed that of the
altitude, and as its sign, as well as amount, can nearly be esti-
mated from the position which the observed bodies occupy,
essential errors may easily be avoided; moreover, they offer
an easy means of reducing the refraction to the points of the
limbs brought into contact when observing their distance, as
shall be shown in what follows: To deduce from the ob-
served altitude of the upper or lower limb the apparent alti-
tude of the centre, the horizontal semidiameter must be di-
minished for refraction by a correction to be taken out from
the table at the end of this paper: in order to find the vertical
diameter, the moon’s semidiameter requires moreover the
usual augmentation on account of parallax. From another
table, too extensive for our limits here, the reduction from the
apparent to the true zenith must be taken, which may also
be computed after the following formula :

sin ¢ sin h —sindS 2sin¢

ss cos2¢ = tang. reduction

cos h gr AFF ? 6 ‘
a*—b*

neglecting higher powers of a?—d*. This reduction assum~-

, rT rea aed rt , sing
ing the ratio of axes nae is very nearly = 1360". i

(sin g sinh — sin’), where # denotes the true altitude, ¢ the
latitude, ® the declination, attention being had to its sign.
Tables for the correction of the horizontal parallax on ac-
count of the spheroidical figure of the earth are contained in
several nautical works, or supplied by a simple calculation.
Let us designate by,
_ D, the apparent distance of centres;

d, the distance of the points of contact or observed distance
of limbs ;

376 Mr. Rumker’s new Method of

H, the greater, / the less, apparent altitude of centres ;

H’, the greater, 4! the less, apparent altitude of the points

of contact ;

7, the semidiameter parallel to the horizon (augmented if

the moon’s) of the upper body ;

e—7, the correction of the upper altitude ;

oe! —z’, the correction of the lower altitude ;

§, the true distance of the limbs, to which the equatorial ho-
rizontal semidiameters must be added to obtain the true di-
stance of the centres.

Let A be the distance of the middle of the apparent di-
stance of the centres, and A’ the distance of the middle of the
apparent distance of the limbs from the highest point in the
apparent distance or its prolongation, that is, from that point
in a great circle drawn through sun and moon where the
effect of parallax and refraction is 0,—then is

tan 4 (H—A) Sas
tani (H + %) tan} D and A’=id+r4+A-—iD
whence we obtain the apparent altitudes of the points of con-
tact,

sin H! =

tan A =

cos (1d — A’) sinH gil eprgpmeteos (4 d+ A’) cosh
cos (1 D—A) ~ cos (4 D4-A)

which are also found by H’/—H =, tan HD tan (} D—A) and
h'—h =r tanh tan(} D+A) and adding f’/—H and /'—h
to the apparent altitudes of the centres above the sensible hori-
zon and subtracting from the sum the change of refraction from
H’ to Hand /' to 4. But if A>3 D, H'—H is to be sub-
tracted from the greater altitude, and the change of declina-
tion to be added thereto; the same method is to be followed
when the distance of the moon’s remote limb from a star is
observed. It being, however, not so much an error in the al-
titude as an error in the refraction that materially affects the
calculation, and this refraction not being sensibly altered by
a few seconds of difference of altitude, the change of refraction
may safely be neglected. For the apparent altitudes of the
points of contact of the sun and moon above the horizon,
compute strictly the refractions g and e’ with regard to baro-
meter and thermometer, and add the sum of these refractions
to the observed distance of the limbs. From the same appa-
rent altitudes of the points of contact above the sensible hori-
zon, find, by applying thereto the above-stated reduction, the
altitudes H’ and /’ with respect to the true zenith, and de-
duct from each the corresponding refraction found before, and
compute for the rest the parallaxes in altitude z and 7’, and

reducing Lunar Observations. 377

subtract their sum ++’ from the observed distance augmented
by the refractions, and call the remainder d + ¢ + oe’ —2— 7!

Find also for each altitude the corrections g—z and ¢/ —7';
then is

gees COS (H'+3d—A’).(e—7) __ cos (2'+3d+A').(e!—7')

cos H’cos(id—A') . cosh’ cos(1d+A )
4 00s (H’ +3 4d—A’) cos [H'— (3 d—A')] (g—z)?. sin 1”
2 tan d cos* H’ cos? (1 d— A’)
4, 88 (A! +4 d+A) cos [h'—($ d+ A')] (g!—2z!)?. sin 1! me

2 tan d cos* h’ cos? (1 d— A’) ae
If we call the first correction «, the second £, then is:
y sin 1/
baba BH (pe baat (fa 3 A ay

to which both horizontal semidiameters are to be added to
find the true distance of the centres. The square of the sun’s
correction can always be neglected, and that even of the moon’s
correction disappears when d is near 90°, or when the moon’s
correction is small. All four corrections disappear when the
distance is the supplement of the sum of the altitudes ; but
when the distance is equal to the difference of the altitudes,
all other corrections vanish except the first one, which be-
comes = 2 (p—7).

The first two corrections only, however, need be computed,
as the others can be taken as a small third correction from a
table contained in most nautical works, with its sign, which
becomes negative when 6>90; so that this method has the ad-
vantage that no difference of cases need be attended to, as in
that of Witchell’s, whose example I have followed in the com-
putation of it. For if we call, of the two first corrections, the
one proceeding from the sun S and that from the moon M,
then is,

§ = 6— S+M+ third correction,

which latter one, in the absence of the tables, may be found by
the formula ((’s corr. —} M).M cot 6 sin 1",

To the semidiameters, which are to be added to the ob-
served distance to obtain the apparent distance of the centres,
a correction should be applied on account of inclination to
the horizon, for which Mendoza Rios has given a table. This
inclination to the horizon is found by sin. inclination =
sin Hsec(4D— A). In the subsequent example this incli-
nation is = 90°; so that the vertical semidiameters have been
used. As however the distance of the centres enters only into

Third Series. Vol. 8. No. 48. May 1836. 2Q

378

Mr. Rumker’s new Method of

the approximative calculation, the correction for inclinatron
may be omitted in this method.

To illustrate this method we shall choose the example given
by Professor Schumacher in his Ephemeris for 1835, which

from 21 feet elevation

come the following :
ist Example. Jun

172° 22! E. longitude,

above the level of the sea would be-

e 18, 1835, in 23° 57' N. latitude, and
the following observations were made.

Therm. 90 Fahr.; barom. 28°6 Engl.

© Lower Limb. 83 55 35
Dip — 4 21

83 51 14

©’s semid. + 15 45

App.alt. 84 6 59
Red. to true zen. + 35

© Upper Limb. 5 15 50

Bos et sae tee anee — 4 21
5 11 29
C’s hor. semid. 15 4
Refraction —20 —14 45 vert.semid.
Parallax +1

H= 84 7 34 Ap. alt. above hor. 4 56 44
Reduct. to true zen. +1 23
EEN G/
Observed Distance of Limbs.
d = 90 17 16 4d= 45 8 38
semid. © = 7 15 45 r= 15 45
semid. (« = 7! 14 45 A. =, 39°37 57
90 47 46 = D 4D= 45 23 53
A’ = 39 38 27
Calculation.
H 84 7 34
he a8 9
H+h 89 5 41 4(H+h) 44 32 50 cot 0-006864
H—h 79 9 27 4(H—A) 39 34 43 tan 9-917318
4D 45 23 53 cot 9-993966
A 39 37 57 tan 9-918148
4D—A 5 45 56 tan 9-0042 3D+A 85 7 50 tan 1-0607
H 84 7 34 tan 0-9877 hk 458 7 tan 8-9392
r 15 45 log 29754 7 15 5 log 2-9567
H’—H_ 15 27 log 2:9673 h'—h 15 5 log 2:9567
App.alt.84 6 59 App.alt. 4 56 44
84 22 26 refr. ¢/=10! 5 11 49
Reduc. zen. 309 Change refr. fork'—h = 20
H' 84 23 1 5 11 29 refr. R = 8! 19"
Refract. 5 Red, zen. 1 23
84 22 56 par, «= | 5 12 52
— Ref. 819
r—-- = —4 eee ae
P_R = + 46 42 5 4.33. pat. R=> 60 1
P+x—-e—-R = 46 38 P—R = +46 42
d= 9017 16
3 = 89 30 38

reducing Lunar Observations. 379

3445 8 38 4445 8 38
A! 39 38 27 A! 39 38 27
4d—A'= 5 3011 sec 000201 4d+A!’ 84 47 5 sec 1-04144
H’ 84 23 1 sec 1-00936 h' 5 12 52 sec 0-00180
H’+3d—A’ 89 53 12 cos 7-29623 h'+3d+A! 89 59 57 cos 5:16270
e—x = 4" log 0-60206 R'—P’ — 46! 42" log 3-44747
Se — 0-08 log 8-:90966 M = + 0"-45 log 9-65341
Vi + 0-45
5= 89 30 38-00
§= 89 30 38-37
—— 15 45
= 15 4
———————— Diff.
True pa : a 0° 1! 241.6 pr. log. 92-1065
From Nautical Alm. prap. log. for midnigh 0°3250

Mean time at Greenwich 12 2 58:5 pr. log 1°7815
Mean time on board 23 34 52:0

Longitude 11 31 53-5 East.

2nd Example. October 16, 1835, in 53° 33’ N. latitude,
and 9° 58! E. longitude, at 10 A.M, mean time, the following
altitudes of the sun’s and moon’s lower limb and distance of
their limbs were observed. Elevation of the eye 20 feet.
Barom. 30°2; therm. 40.

© »)
23 41 31 45 30 0
Dip — 415 dip — 415
23 47 16 45 25 45

Dim. for refr. aug. for par.

© semid. 16 4: 6 (’shor.sem.15 18-7
o0}+ 16 26 103 28:8
ee dim. for ref. 0:4

23 53 186 ee eS
Reduction + 9 31:0 45 41 13:8
— Reduction + 4 53
i= iP4 nw Qv49: ———E
H 45 44 68
Distance.
d = 72 41 13 kd = 36 20 365
15 29:2 r= 15 29:2
16 46 A= 20 18 38:0
D= 73 12 46:8 56 54 44-0
4D 36 36 23:0
A' = 20 18 21:0

2Q2

380 Mr. Rumker’s new Method of
H=45 46 7
A=24 2 50
H+h=69 38 57 3(H+A) 34 54 28 cot 0-1562619
H—A=21 43 16 4(H—A) 10 51 38 tan 9-2829749
$D 36 36 23 cot 0-1291056
A 20 18 38 tan 9-5683424
(4 D—A) 16 17 49 tan9:46589 (4D+A)56 55 1 tan 0-18611 —
H 45 46 7 tan 0-01165 h 24 250 tan 9-64954
7 15 29 log 2:96801 r 16 5 log 2-98453
H'—H 4! 39" log 244556 hi—h 11! 1" — Jog 282018
45 41 14 23 53 19

45 45 53 refr. 0! 58’)
Reduction + 4 53

H’ = 45 50 46
Refraction 58

45 49 48 parall. 39’ 41

e—x = — 38' 6".0
g—n = + 2 555
e—x+e—7' = — 36 055

d = 72 41 13-0
3 72 5 12"5

4d = 36 20 36 $d
A! = 20 18 21 Al
(;d—A') 16 215. sec 0-01724 Ad+A!
H’ = 45 49 48 sec 0-15690 h!
H’+4d—A'= 61 52 3 cos 9-67349 = =h'+3d+A'=
e—= = 38 6 log 335908 e'— a!
M = + 26 49-5 log 3:20671 S=
= 39°7
3 = 72 5 125
72 31 22:3
3rd corr. + 36
6 = 72 31 259
jp == 15 18:7
r= 16 46
y —- Diff.
True dist. of centres oe rs ee 0° 9" 49!"8 ... pr. log. 12627
From Nautical Almanac pr. log. 0'3111

eeeeee

Mean time at Greenwich 21 20 7
Mean time at ship 22 0 0
Longitude in time 0 39 53 Kast.

pr. log. 0°9516

24 4 20 ref. cor. 2'13'"2
+ 9 31

24 13 51 parallax 7-7

e'—r" 2 5:5
36° 20! 36"
20 18 21_
56 38 57 sec 0-25982 —
24 13 51 sec 0-04005 —
80 52 48 cos 9-20004 ©

2' 5"5 log 209864 ,
39-68 log 1-59855 —

reducing Lunar Observations. 381

The third correction is to rectify the error committed in
assuming one side of a spherical jtriangle equal to the adja-
cent segment of its base cut off by a perpendicular from the
vertex of the opposite angle, which error will diminish with
the angle contained between the above side and the base.

Suppose a and c to be two sides of a triangle, and } and d
their adjacent segments, and » = a — 6, then is tan $p
_ tan} (c—d).tan § (c+d)
iF ian(O+$u)
approximations, supposing it in a first one = 0. But
tan} (c —d).tan}(c+d) = tan’? 3A, if we denote by A the

tang? 5A
tang (b+ #)

Whence we find the following general expression for iy,
which may be reduced accordingly as circumstances allow :

Suppose,

» whence » may be found by

perpendicular. And tang }p =

tang 5A Bates
1+tang? $a — f_tan?3a ve tan22A
___ | tan d+tan? 4a + | tand+tan?3a_
tand (tan d+tan? 3a —tanbf_tan23a q 2+-&e. | tan b-+tan® $A tan b-+tan?$
tan 6+tan2 3a tan b+tan2 32 | tand+ tan 6+
tan b+tan? 3a tand+tan23a
tan 6+... tan ...J

then is: tang b tang $1» = N—N?+ N®— N*4+ N5— 4 — ...
py. becomes, therefore, negative when > 90, and is = 0 when
6 ="90°.

Walbeck, who proposed computing for the time of obser-
vation, reduced for the estimated longitude from the first meri-
dian, the apparent distance as seen from the place of obser-
vation; and to derive, by a comparison of this computed
distance with the observed one by means of the moon’s ap-
parent horary motion, the error of the estimated longitude, has
remarked already the necessity of computing the refraction
for the points of contact when the altitudes are low, in the
note to page 15 of his Dissertatio de Modo reducendi Distan-
tias, Abo 1817: “ Si rigorose calculaveris, refractio non pro
Centro lunz sed puncto limbi quo distantia capitur sumenda
est. Inutile vero est, calculum talibus minutiis molestum red-
dere, que preterea, nisi sit luna vel sol horizonti proximus
nullius sunt momenti. Ex hac etiam caussa minimee altitu-
dines evitari debent.” But low altitudes are better than none,
and cannot always be avoided.

Walbeck found from latitude, declination and horary angle,
the altitudes, parallactic angle and the corrections of the alti-
tudes, and thence the apparent declinations and right ascen-

382 Mr. Rumker’s new Method of

sions of both bodies, and computed thence, with true dif-
ference of right ascensions and true declinations, the true di-
stance, and withthe apparent difference of right ascensions
and apparent declinations, the apparent distance, and the
differences A‘— A of these apparent and true distances for
three successive equally distant periods ¢,, ¢,, ¢3, and denoted
by «5 w2, wa, the remainders left by a subtraction of these
differences A‘— A from one another.

Suppose now w, = A + Bt, + Cz#,’, a, = A+Bé, +Ct,’,
and a, = A+Bz#,+Cz,?, then is, ©

w, (t3—ty) + &(t;—ts) + 3 (ta—t))
(t.—7,) (t3—t,) (tg—ta)

Parra
t,—t,

C=

p= C(¢,+7¢,) and A = w, —¢,(B+#, CQ),
whence any other # = A + Bt+C# for any given ¢ may
be found, provided A is assumed proportional to the given 2;
Then w+ sum of apparent semidiameters applied to the distance
taken from the Naut. Almanac for the time reduced for longi-
tude to the first meridian, gives the apparent distance of limbs,
which by a comparison with the observed distance will show
the error of the assumed longitude. This rather laborious
proceeding may be simplified by taking also from the Nauti-
cal Almanac for the same reduced time, together with the
other elements, the true distance of the centres, and finding by
differ. R cosin declin.
sine distance
the sun, as well as for the moon; then a subtraction of the
parallactic angles from the angles of position will give the
above-mentioned angles S and M, whence will be found,
A’—A = (a'—¢') cos M—(g— =) cos S+ third correction,
where S and M are considered acute; any doubts whether the
angles of position are obtuse or acute, are easily decided, and
the reduction of the refraction to the points of contact is ac-
complished in the same manner as before. This method offers
advantages when by a series of observations the longitude of
a place on shore is to be determined. At sea it would be
unwise to neglect the opportunity of observing the altitudes
above the visible horizon, considering that the latitude enter-
ing into the calculation of the altitudes rests upon no firmer
base than the contemporaneously observed altitudes, and re-
quires moreover a very unsafe reduction by dead-reckoning
to the time and place of lunar observation, not to mention

, the sines of the angles of position for

reducing Lunar Observations. 383

that the error of the estimated longitude affects the elements
entering into the computed altitudes taken from the Nautical
Ephemeris, of which the observed altitudes are independent.
Immediately before or after new moons the faint image of the
moon when she is high may be difficult to bring down to the
horizon, and occupy such a position in respect of it, that
neither upper nor lower limb can be correctly observed. The
computed altitude of a fixed star is also more to be depended
on than its observed one; in these cases it is better to com-
pute, particularly the high altitudes, with the reduced geo-
centric latitude, as the refraction corresponds thereto, which,
by rights, ought to have been taken from the tables for the
angle of the ray of light with the normal or with its comple-
ment; the altitude above the sensible horizon then requires only
a trifling correction.

When the lower object is a star, and the moon’s altitude is
not too small, the usual methods are sufficiently correct, pro-
vided allowance is made for barometer and thermometer.

Here follows a specimen of the table of the contraction of
the vertical diameter on account of the refraction, which is
calculated for the mean diameter of the sun, and for mean re-
fraction.

Correction for Correction for Correction for
Altitude. Tower
Limb. |

4°50"! —
4 45
40
35

Lower | Upper i c Upper
Limb. | Limb. i Limb.

fe}
=r

= OW Ph or
cooceccos

9
9
9
,
9
9
8
8
8
8
8
8

BOO NIA ARAAaNNS
mm Ro
i — i — i — i — i — i —
WCwOWWWAEL EE RE PR
v

NNN
c & or
—i——)

or

[ 384 ]

LXX. Observations on the Lines of the Solar Spectrum, and
on those produced by the Earth's Atmosphere, and by the
Action of Nitrous Acid Gas. By Sir Davin Brewster,
K.H., V.P.R.S. Ed.*

[NX a paper on the Monochromatic lamp, &c., read before

the Royal Society of Edinburgh on the 15th April 1822,
and published in their Transactions, I recorded some of my
earliest experiments on the action of coloured media on the
solar spectrum. ‘These experiments were continued at irre-
gular intervals, with the view of obtaining distinguishing cha-
racters of coloured media, of investigating the cause of the
colours of natural bodies, and of examining more correctly
the phzenomena of the overlapping colours of equal refrangi-
bility, which I had announced in the paper already referred
to. The results to which I was conducted on the two last of
these subjects have been already published, in two papers, one
on the analysis of solar light, and the other on the colours of
natural bodies.

The first and the principal object of my inquiries, namely,
the discovery of a general principle of chemical analysis, in
which simple and compound bodies might be characterized
by their action on definite parts of the spectrum, still re-
mained to be pursued. ‘The coloured juices of plants—arti-
ficial salts and their solutions, and various glasses and mi-
nerals—had afforded me many beautiful examples of this
species of action; and after determining the locality of these
actions in reference to Fraunhofer’s principal lines, and their
intensity, as depending on the thickness of the absorbing me-
dium and the brightness of the spectrum, I was able to di-
stinguish all such compounds, by merely looking through
them at a well-formed spectrum. Even in those cases where
the eye could recognise no difference between the colours of
two substances that exercised different specific actions upon
light, their discrimination was instantly effected by viewing
them through a standard coloured medium.

As some of these bodies attacked the spectrum at fwo,
three, four, and even five or more points at once, it became
probable that the number and intensity of such actions de-
pended on the number and nature of the elements which en-
tered into the composition of the body, or, what is nearly the
same thing, that it was the sum of all the separate actions of
such elements; and hence the next step in the inquiry was,
to determine the action of elementary bodies on the solar
spectrum. ‘This inquiry was not limited to coloured bodies,

* From the Transactions of the Royal Society of Edinburgh, corrected.

Sir David Brewster on the Lines of the Solar Spectrum. 385

for it is quite possible that a body may transmit light perfectly
white, and yet exercise a definite action in absorbing various
parts of the spectrum. The only physical condition which
is necessary in this case is, that the sum of all the rays thus
absorbed, shall constitute white light.

The first substances which I examined were sulphur and
iodine vapour. The sulphur attacked the violet end of the
spectrum with great force, and, when combined with arsenic,
in the form of native orpiment, its absorptive power for the
same colours was greatly increased. Even with the thinnest
film that I could detach, and not exceeding the two-hundredth
part of an inch, the spectrum was, as it were, cut sharply in
two near the boundary of the green and indigo spaces, and
this body possessed the very uncommon property of having
nearly the same colour at small as at great thicknesses. By
increasing the thickness, the absorption advances almost im-
perceptibly from the remaining blue border, and if the trans-
parency continued, the transmitted light would certainly be-
come red at great thicknesses,—a property which may be
communicated transiently to the thinnest plates, merely by an
increase of temperature.

The iodine vapour acted powerfully upon the middle of the
spectrum, and, by an increase of thickness, gradually extended
its absorption towards both extremities; but more rapidly to-
wards the violet one, so as to show that the final colour must
be a homogeneous red*.

In so far as these two experiments went, they were highly
favourable to the speculation which had at first presented it-
selfto me. My attention was now directed to the action of
gaseous bodies, and the first trial which I made was with
nitrous acid gast. The result of this experiment completely
destroyed the hypothesis which had appeared so plausible,
and presented me with a phenomenon so extraordinary in its
aspect,—bearing so strongly on the rival theories of light,—
extending so widely the resources of the practical optician,
and lying so close to the root of atomical science, that I am
persuaded it will open up a field of research, which will ex-
haust the labours of philosophers for centuries to come.

The spectrum of Newton, and of all the philosophers of
the 18th century, was a parallelogram of light, with circular
ends, in which the seven colours gradually shaded into each
other without any interruption. The illumination was a maxi-
mum in the yellow rays, and the light decayed by insensible

* [See Lond. and Edinb. Phil. Mag., vol. ii. p. 362. ]
+ [See Lond. and Edinb. Phil. Mag., vol. ii. p. 381

By
Third Series. Vol. 8. No. 48. May 1836. 2 hh

$86 Sir David Brewster on the Lines of the Solar Spectrum,

degrees towards the red and the violet extremities. In the
year 1808, Dr. Wollaston conceived the happy idea of examin-
ing a beam of light, that passed through an aperture only
the twentieth of an inch wide, and he was surprised to see it
crossed by seven dark lines, perpendicular to its length.

About ten or twelve years afterwards, the celebrated op-
tician Joseph Fraunhofer, without knowing what had been
done by Dr. Wollaston, observed the spectrum formed by the
sun’s light transmitted through small apertures; and by ap-
plying a telescope behind the prism, he discovered about 600
parallel dark lines traversing the spectrum. As no such lines
appeared in the spectra of white flames, Fraunhofer considered
them as having their origin in the nature of the light of the
sun. The strongest of these lines were seen in the spectra of
the Moon, Mars, and Venus, and, by means of very fine in-
struments, he was able to detect one or two of them with
other new lines in the spectra of Sirius and Castor.

Such was the state of the subject, when I made the experi-
ment already referred to on nitrous acid gas. Upon examin-
ing with a fine prism of rock-salt, with the largest possible
refracting angle, (nearly 78°,) the light of a lamp transmitted
through a small thickness of the gas, whose colour was a very
pale straw yellow, I was surprised to observe the spectrum
crossed with hundreds of lines or bands, far more distinct
than those of the solar spectrum. The lines were sharpest
and darkest in the violet and blue spaces, fainter in the green,
and extremely faint in the yellow and red spaces. Upon in-
creasing, however, the thickness of the gas, the lines grew
more and more distinct in the yellow and red spaces, and be-
came broader in the blue and violet, a general absorption ad-
vancing from the violet extremity, while a specific absorption
was advancing on each side of the fixed lines in the spectrum.
It was not easy to obtain a sufficient thickness of gas to de-
velop the lines at the red extremity, but I found that heat
produced the same absorptive power as increase of thickness,
and, by bringing a tube containing a thickness of half an inch
of gas to a high temperature, I was able to render every line
and band in the red rays distinctly visible.

The power of heat alone to render a gas, which is almost
colourless, as red as blood without decomposing it, is in it-
self a most singular result; and my surprise was greatly in-
creased when I afterwards succeeded in rendering the same
pale nitrous acid gas so absolutely black by heat, that not a ray
of the brightest summer’s sun was capable of penetrating it. In
making this experiment, the tubes frequently exploded, but,
by using a mask of mica, and thick gloves, and placing the

and on those produced by the Earth's Atmosphere, §c. 3857

tubes in cylinders of tinned iron with narrow slits to admit
the light, there is little danger of any serious accident.

When the gas is in the liquid state, it produces none of the
fixed lines which I have described, and exercises no other
action upon the spectrum than any ordinary fluid of the same
orange colour.

In examining the structure of the solar spectrum, Fraunho-
fer seems to have put forth all his strength in determining
the position of the principal lines, A, B, C, D, E, 6, I’, G and
H*, which he had selected as equidistant as possible, for the
purpose of measuring their angular distances in different
media, and thus obtaining the most accurate data for the con-
struction of the achromatic telescope. ‘These measures he
has given with the greatest exactness for various kinds of
crown and flint glass and for a few fluids, and be has thus put
it into the power of the practical optician to construct achro-
matic object-glasses, with a degree of certainty and perfection
hitherto unknown.

This method, however, notwithstanding its high value, is
not easily applicable in practice, and from the nice observa-
tions which it involves, we have reason to believe that it has
not been used by any other artist than Fraunhofer himself.
The difficulty of procuring out of the mass of glass to be em-
ployed, prisms sufficiently pure to show such narrow lines as
E, or the two which constitute D+,—of obtaining the sun
when his light is wanted, and of observing and measuring the
distances of the fixed lines ina spectrum constantly in motion,
are insurmountable obstacles to the general adoption of so
refined a method of measuring dispersive powers.

From all these difficulties, the discovery of lines in the ni-
trous acid gas spectrum completely relieves us. As the lines
whose distances are required, may be made as broad and
black as we please, prisms of ordinary purity are suflicient to
exhibit them in perfect distinctness. The artificial light of a
lamp can be commanded at any hour, and as its rays are ab-
solutely fixed, the least experienced observer can have no dif-
ficulty in measuring the distances of the fixed lines, and thus
obtaining, with extreme accuracy, all the data for the con-
struction of achromatic instruments.

But it is not merely to this practical purpose that the
gaseous lines are singularly applicable. Among the various
solids and fluids in nature, there are very few sufficiently pure
and transparent, to enable us to see through them the lines of

* Six of these, viz. B, D, 6, F, G, and H, were discovered by Dr. Wollaston.
+ These lines are also the most important, as the most luminous part of
the spectrum lies between them.

2R-2

388 Sir David Brewster on the Lines of the Solar Spectrum,

the solar spectrum, so as to enable us to measure their refrac-
tive and dispersive powers with minute accuracy, whereas the
gaseous lines can be rendered visible, however imperfectly the
spectrum may be formed. In determining the various ele-
ments of double refraction and polarization, and in all optical
researches where the phenomena vary with the refrangibility
of the rays, the gaseous lines will hereafter perform a most
important part.

Had the solar lines been much broader than they are, we
might have been able, by means of minute thermometers, to
have ascertained the temperature of all those parts of the
spectrum where there was no light, and thus to have deter-
mined whether or not the rays s of light and heat are separate
and independent emanations. The ‘phenomena of the nitrous
acid gas spectrum, the lines of which can be widened at plea-
sure, “enable us to perform this and other interesting experi-
ments, and thus to decide many important questions in the
theory of radiant matter.

From the various experiments which I had made on the ae
sorptive action of coloured media, I was led to a general prin-
ciple, which, in that stage of the inquiry, appeared to possess
considerable importance. The points of maximum absorption
exhibited a distinct coincidence with some of the principal
dark lines in the solar spectrum, and thus indicated that these
lines marked, as it were, weak points of the spectrum, on
which the elements of material bodies, whether they existed
in the solar atmosphere or in coloured solids and fluids, ex-
ercised a particular influence. ‘These actions, however, were
so indefinite, that, with the exception of the oxalate of chro-
mium and potash*, a salt of most remarkable properties, they
never appeared in the form of lines or distinct bands. ‘The
light which was left shaded into the dark spaces, and there-
fore) notwithstanding the general coincidence which I had
observed, the phenomena of ordinary absorption could not be
identified with those of the definite actions by which the solar
lines are produced. i

This point of similarity, however, led me to institute a di-
ligent comparison between the solar lines and those of the
nitrous acid gas spectrum; and it did not require many ex-
periments to prove, that there existed between these two
classes of phanomena a most remarkable coincidence. — In
order to afford ocular demonstration of this fact, I formed
the solar and the gaseous spectrum with light passing through
the same aperture, so that the lines in the one stood opposite

* [See Lond. and Edinb. Phil. Mag.,, vol. ii. p. 362 ; and vol. vii. p. 436.]

and on those produced by the Earth's Atmosphere, §c. 389

those on the other, like the divisions in the vernier and the
limb of a circle, and their coincidence or uon-coincidence
became a matter of simple observation. I then superimposed
the two spectra, when they were both formed by solar light,
and thus exhibited at once the two series of lines, with all
their coincidences, and all their apparent deviations from it.
Professor Airy, to whom J showed this experiment, remarked,
that he saw the one set of lines through the other, which is
an accurate description of a phenomenon, perhaps one of the
most splendid in physical optics, whether we consider it as
appealing to the eye or to the judgement.

The general coincidence, thus cognisable by the eye, re-
quires to be more particularly explained. Though some of
the larger lines in the gaseous spectrum coincide with some
of the larger ones in the solar spectrum, yet, In many cases,
faint and narrow lines in the one coincided with strong and
broad lines in the other; and there were some strong gaseous
lines, and even broad hands, to which I could discover no
counterpart in I’raunhofer’s map of the spectrum, which, at
this stage of my inquiry, was the standard to which I appealed.
This discrepancy at first embarrassed me, and, as I observed
it in parts of the spectrum where Fraunhofer had laid down
every line which he had seen with his finest instruments, I
abandoned all hopes of being able to establish the general
principle of their identity. 1 was therefore obliged either to
renounce this principle as one contradicted, or rather not con-
firmed by observation, or to consider Fraunhofer’s delinea-
tion as in fault, and to enter upon the Herculean task of
making a better map of the spectrum.

The magnificence of Fraunhofer’s instruments,—the means
of nice observation which he had at his command,—and his
great skill as an observer, were considerations which long de-
terred me from even attempting to repeat his examination of
the spectrum. Possessing such inferior means, and situated
in so unfavourable a climate, I should have felt the attempt
as presumptuous; but in the comparison which I had already
made of the gaseous and solar lines, I had detected grave
errors, and inexplicable omissions, in Fraunhofer’s map, and
was disposed even to adopt the suggestion of Mr. H. F. Tal-
bot, (to whom I mentioned the fact, and who had the same
confidence that f had in Fraunhofer’s accuracy,) that a change
might have taken place in the light of the sun itself, and that
the delineation of the Bavarian philosopher might have been
perfecily accurate at the time when it was executed. This
supposition, however, became less and less tenable as I pro-
ceeded in the identification of the two classes of lines; but

390 Sir David Brewster on the Lines of the Solar Spectrum, .

even if it had been otherwise, it would have added a still more
powerful motive, while it afforded the best apology for under-
taking a new delineation of the spectrum.

The apparatus which I had at my command for this inves-
tigation were two very fine rock-salt prisms, executed by my-
self; a large hollow prism made of plates of parallel glass for
holding fluids; a fine plate glass prism, by Fraunhofer, and
which I owe to the kindness of Mr. Talbot; a copious supply
of oil of cassia and oil of cinnamon, which Mr. George Swin-
ton transmitted to me from Bengal with his usual liberality ; a
good achromatic telescope, by Berge; and an excellent wire
micrometer by Troughton. ‘To this apparatus Mr. Robison
made two important additions, which he executed with his
own hands, the one a brass stand with a variable aperture for
admitting the incident light, and the other a stage for holding
and‘ adjusting the prisms in front of the object glass; and I
have recently been favoured by Sir James South with the
use of his fine, five-feet achromatic telescope, executed by
Dollond.

After a little practice in the observation of the solar spec-
trum, I discovered most of the lines, which I had in vain
sought for, in Fraunhofer’s map, as the counterpart of those
in the gaseous spectrum. I saw well-marked groups, of which
he had only given one of the lines, and shaded bands, and
well-defined lines, which his methods of observation had not
permitted him to discover. After I had laid down all the
principal features in the spectrum, I was able to examine the
two classes of lines pari passu. ‘The action of the gas upon
invisible lines in the spectrum rendered them visible by slightly
enlarging them, and this enlargement of a ‘solar line indi-
cated the existence of a corresponding line in the gaseous
spectrum.

By this double process, and by methods of observation
which I believe have never before been used in optical re-
searches, I have been able to execute three different maps of
the spectrum; first, a map of the lines in the solar spectrum;
secondly, a map of the same spectrum, exhibiting at the same
time the action of nitrous acid gas upon solar light, previously
deprived of a number of its definite rays; and, thirdly, a map
showing the action of the gas upon a continuous and uninter-
rupted spectrum of artificial white light. The general scale
of these delineations is, four times greater than that of Fraun-
hofer, but some portions of them are drawn on a scale ¢welve
times greater, which became necessary from the impossibility
of representing in narrower limits the numerous lines and
bands which I have discovered. The length of Fraunhofer’s

-and on those produced by the Earth’s Atmosphere, Sc. 391

spectrum is 15}inches. Mine, upon the same scale, is nearly
17 inches. The length of the general spectrum, which I have
delineated, is about five feet 8 inches, and the length of a
spectrum, corresponding to the scale on which I have deline-
ated parts of it, is seventeen feet.

Fraunhofer has laid down in his map 354 lines, but in the
delineations which I have executed, the spectrum is divided
into more than 2000 visible and easily recognised portions,
separated from each other by lines more or less marked, ac-
cording as we use the simple solar spectrum, or the solar and
gaseous spectrum combined, or the gaseous spectrum itself, in
which any breadth can be given to the dark spaces.

The suggestion of Mr. Talbot induced me to watch nar-
rowly the state of the defective solar lines at different seasons
of the year, in order to observe if any change took place in
the combustion by which the sun’s light is generated, or in the
solar atmosphere through which it must pass. Such changes
I have found to be very general in every species of terrestrial
flame. The definite yellow rays which exist in almost all
white lights, flicker with a variable lustre; and analogous rays
in the green and blue spaces proceeding from the bottom of
the flame, exhibit the same inconstancy of illumination. In
the course of the winter observations, I observed distinct lines
and bands in the red and green spaces, which at other times
wholly disappeared; but a diligent comparison of these ob-
servations soon showed, that these lines and bands depended
on the proximity of the sun to the horizon, and were produced
by the absorptive action of the earth’s atmosphere. I have no
hesitation, therefore, in affirming, that during the period of
my own observations, no change has taken place either in
the dark lines or luminous bands of the solar spectrum; a
result which seems to indicate, that the apparent body of
the sun is not a flame in the ordinary sense of the word,
but a solid body raised by intense heat to a state of bril-
liant incandescence. )

The atmospheric lines, as they may be called, or those lines
and bands which are absorbed. by the elements of our atmo-
sphere, have their distinctness a maximum, when the sun
sinks beneath the horizon. ‘The study of them, consequently,
becomes exceedingly difficult in a climate where this luminary,
even in a serene day, almost always sets in clouds; but as I
have availed myself of every favourable moment for observa-
tion, | have been able to execute a tolerably accurate delinea-
tion of the atmospheric spectrum.

It is a curious circumstance, that the atmosphere acts very
powerfully round the line D, and on the space immediately on

392 Sir David Brewster on the Lines of the Solar Spectrum.

the least refrangible side of it. It develops a beautiful Jine in
the middle of the double line D, and by enlarging a group of
small lines on the red side of D, it creates a band almost as
dark as the triple line D itself. It widens generally all the
lines, but especially the darkest one which I call m between
Cand D._ It develops a band on‘the least refrangible side of
m, and it acts especially upon several lines, and develops a se-
parate band on the most refrangible side of C. The lines A,
B, and C are greatly widened, and lines and bands are parti-
cularly developed between A and B, and generally through-
out all the red space.

Most of the lines thus widened by the atmosphere are faint
lines previously existing in the spectrum, and I have no doubt
that they would be seen in the spectrum of the lime ball light
condensed by a polyzonal lens, and acted upon by thirty miles
of atmosphere. .

The absorptive action of the atmosphere shows itself in a
less precise manner in the production of dark bands, whose
limits are not distinctly defined. A very remarkable narrow
one, corresponding to one produced by the nitrous acid gas,
is situated on the most refrangible side of C. Another very
broad one lies on the most refrangible side of D, close to a
sharp and broad band of yellow light, displayed by the general
absorption of the corresponding part of the superimposed blue
spectrum. There is also an imperfectly defined atmospheric
action, corresponding to a group of lines where Dr. Wollas-
ton placed his line C.

This general description of the atmospheric lines, while it
indicates the remarkable fact, that the same absorptive ele-
ments which exist in nitrous acid gas exist also in the atmo-
spheres of the sun and of the earth, leads us to anticipate
very interesting results from the examination of the spectra of
the planets. Fraunhofer had observed in the spectra of Venus
and Mars, some of the principal lines of the solar spectrum.
This, indeed, is a necessary consequence of their being illu-
minated by the sun, for no change which the light of that
luminary can undergo, is capable of replacing the rays which
it has lost. But while we must find in the spectra of the pla-
nets and their satellites, all the defective lines in the solar
spectrum, we may confidently look for others arising from the
double transit of the sun’s light through the atmospheres
which surround them.

Allerly, April 12, 1833.

F989 5.

LXXI. ‘On the Theory of Vanishing Fractions, in reply to
the Observations of Professor Young. By W.S. B. Woot-
HOUSE.*

[|X my short but comprehensive essay on the principles of
* the differential and integral calculus, printed in the Ap-
pendix to the Gentleman’s Diary for the years 1835-36, my
expressed object was to remove, as far as was practicable, the
perplexing difficulties usually experienced by those students
who very naturally desire to bring the subject under the gui-
dance and dominion of their reasoning faculties. The theory
of vanishing fractions is well known to be the chief source of
these difficulties ; and it so happens, unfortunately for begin-
ners, that writers have hitherto paid little or no attention to
the strict interpretation that ought to be given, in the general
sense, to a fraction when the values of its numerator and de-
nominator have both absolutely disappeared or become equal
to zero. This part of the subject has been diligently exa-
mined in the second part of my essay, where it is shown that
a fraction in such a state may consistently possess any value
whatever, if it be not limited by a special condition, but that
one particular value only will fulfill the law of continuity
assumed by the successive values immediately before or after
the disappearances take place. It appears, however, that my
explanations, there given, are insufficient to satisfy the scruples
of Prof. Young, who has, in opposition to the principle I have
adopted, entered into a very general statement of his own views
at page 295 of the last Number of the Philosophical Magazine.
The opinions of one so deservedly eminent as my esteemed
friend are entitled to high consideration, and 1 am duly sen-
sible of the respectful and condescending manner in which his
observations are expressed. In a mathematical discussion of
this kind, however, it would have been more desirable had
Prof. Young attached less weight to his supposed evidence of
authority, and applied himself more closely to the demonstra-
tion of his statements, nearly all of which are at direct variance
with my judgement, and therefore, to me, far from being satis-
factory. I here propose a brief and explicit examination of
the most important points that Professor Young has advanced,
and, I hope, with the same earnest anxiety for the spread of
scientific truth that he has been pleased to ascribe to me.

To any person unacquainted with the inquiry, Professor
Young’s assertions would seem to imply that my views were of a
strange and revolutionary description; that they were, in re-

* Communicated by the Author,

Third Series. Vol. 8. No. 48. May 1836. 2 S

394 Mr. Woolhouse on the Theory of Vanishing Fractions,

ality, adverse to the results of our ablest modern analysts, and
directly opposed to well-established truths ;—indeed it would
almost appear that Professor Young himself had contracted that
notion. No idea, however, could be imagined more contrary
to the fact. The new line of theory, adopted and pursued in
my essay, leads to precisely the conclusions subscribed to by
all modern analytical writers, and varies only in the substitu-
tion of strict reasoning in place of the illogical and mysterious
mode of deduction that has all along rendered this most im-
portant branch of mathematics a popular paradox. Profes-
sor Young has quoted two of my most general principles,
which, with one or two more extracts, will convey a pretty
correct idea of the particular view I have taken of the subject.
As these extracts will very much facilitate the present discus-
sion I shall here annex them.

I. As a principle, we have no right to reduce a fraction by dividing its
numerator and denominator by absolute nothing, as the process removes
from the fractions the indeterminate character which they previously
possessed, and which they ought to retain. (Gentleman’s Diary,
Appendix, page 26.)

IT. If, in the investigation of a geometrical problem, the unknown quan-
tity is expressed by a fraction which in a particular case becomes a
vanishing one, the problem in that case will resolve itself into a po-
rism, and the value of the fraction, or unkuown quantity, will then
admit of arbitrary assumption; and a similar result will follow in all
such cases, whatever be the nature of the investigation. (Page 25.)

IIf. Whenever, in an analytical investigation, the resulting expression
for a quantity resolves itself into a vanishing fraction, we may observe,
as a general rule, that either one of the original conditions of the in-
quiry becomes destroyed, or that two or more of them become depen-
dent, and, consequently, whichever way it be, that there is at least one
condition less to fulfill, and that the vanishing fraction is not, restricted
to any determinate value. (Pages 26, 27.) :

IV. When a fraction, which in a particular case becomes a vanishing
one, expresses the value of a quantity which we previously know, from
the nature of the subject, does not become discontinuous in that case,
or generally when such a fraction enters in any equation, the other
terms of which are not discontinuous, the fraction is, under such cir-
cumstances, necessarily limited to continuous values, and consequently,
when the terms vanish, it must take the particular value, (described
in the essay,) or the ordinary result deduced either by the method of
limits or the usual process of differentiation. (Page 29.)

The paragraphs IT. and III., which embody the main -prin-
ciple, are those extracted by Professor Young, who labours
under a misapprehension if he supposes that I contented my-
self with testing their accuracy by two particular examples.
Has Professor Young read the remark on page 26 that im~
mediately follows my examples? Speaking of the examples,
I there add, that “* these are not adduced as curious instances,
but merely as examples of what always takes place in such

in reply to the Observations of Professor Young. 395

cases.” It is here evident that 1 had not contented myself
with testing the accuracy of the propositions by the two par-
ticular examples. On the contrary, my conviction of their
truth was founded on the solid evidence of mental demonstra-
tion, and the examples were adduced for the purpose of illus-
tration without any reference to the proof of the principle
itself, which, in common with the others, may be established
without much difficulty. I shall now proceed at once to the
demonstration of these principles.

First, then, it is required to be shown that, logically, we
have no right to reduce a fraction by dividing its numerator
and denominator by absolute nothing. Let ¢2, $x be two
functions of a variable 2 which do not vanish when «=a; and
suppose another variable y to be so connected with x as to
always fulfill the condition

(vx—a) Ox—y (2 — al > @ = 0. (1)

in which 2, 8, are two positive numerical indices and either
whole or fractional. The value of y deduced from this con-
dition is

(v7 —a) Ou
(x—a)* ox
and takes the most general form of a vanishing fraction. Sup-
pose it to be reduced by dividing the numerator and deno-
minator by (2 — a)’, and it becomes

te = a) Pe Se PP ed ore

= ae RON (a — a) Sectoebie (3)

Let x now be taken equal to a and the expression (2) will
become y = 2, while (3) will give

Oo a > ic}
we 2 if \- = Bo (4)
in a< fp

But if we refer back to the original condition (1), it is plain
that it will be satisfied with 2 = a, independently of the value
of y, that in this case it imposes no limit whatever on the value
of y which is therefore completely indeterminate. It follows
therefore that the result of (2), when x = a, viz. y = 8, must
have the same indeterminate acceptation ; and that the pro-
cess of dividing the numerator and denominator of (2) by
(2 — a)’, (= zero when 2 = a,) which produces (3), and so
determines a particular value for y, is inadmissible when 2=a,
and ought not in that case to be performed. And as the ex-
282

y= eu Mss. (2)

396 Mr. Woolhouse on the Theory of Vanishing Fractions,

pression (2) comprehends every possible case of vanishin
fractions, the reasoning is general, and fully establishes the
position occupied in the first extract. 4

It is here evident that the same objection will apply to the
division by zero of an equation involving two variables, or that
the equation resulting from a division by a common factor is
inadmissible when that factor absolutely vanishes. Thus the
equation (1), when divided by (2 — a)F, gives

(x —a)* "02—you =0,

which would, for « = a, give to y the particular value in (3),
a circumstance quite inconsistent with the nature of the con-
dition involved in the antecedent equation (1), which, in the
case x = a, places no restriction on the value of y. It is also
obvious that the multiplication of an equation, or of the nu-
merator and denominator of a fraction, by zero, is equally ob-
jectionable, as regards propriety of reasoning, since, by that
process, we might pass from conditions that determine par-.
ticular values to others of a totally indeterminate character.
Before quitting this. point it will be well to draw a general
and necessary inference that may, in conjunction with the
fourth extract, contribute in some degree towards the eluci-
dation of the present inquiry. It is this: —That when a quan-
tity, which we know from other considerations ought to have
a determinate value, comes out in a vanishing fraction, or,
vice versa, when a quantity, which we know to be indetermi-
nate, comes out in a determinate form, we may be assured:
that at least one of the steps, in the process of solution, fails
in the manner here explained. :

The proof of the principles contained in the other extracts
immediately follows from the preceding demonstration. Sup-
pose the equation (2) to express the result of an analytical
investigation in which the reasoning throughout is admissible
when x = a, so that no multiplication or division by a power
of x —a occurs in the process. We proceed to show that
the resulting vanishing fraction (2), when x =a, must be in-
determinate in value. The equation (1), which is antecedent
to, and corresponds in signification with, the equation (2), is
satisfied with 2 = a, without any reference to the value of y, be-
cause that equation is divisible by a positive power of « —a.
Since, therefore, in the investigation, no multiplications or divi-
sions have been made by 2 —a or any power of it, it is conclu-
sive that the series of equations, which precede the equation (1)
in the course of reduction, must likewise be divisible by the same
power of z — a, and therefore be satisfied with x = a, inde-
pendently of the value of y. The primitive equation from

in reply to the Observations of Professor Young. 397

which the expression (2) is deduced will consequently, when
x = a, be also satisfied by any value of y._ If this primitive
equation expresses an original condition of the problem, that
condition, therefore, when x = a, cannot limit the variable y,
or the expression (2), to any particular value. If, however,
this equation is produced by a combination of two or more
leading equations of the problem, the circumstance of its
wholly disappearing when x = a, will necessarily lead us to
the conclusion that for this particular value of 2 some depen-
dency exists among those leading equations, and therefore that
one of the original conditions of the problem becomes, in that
case, virtually destroyed. In addition to this proof we may
remark that the expression (3) is legitimately deduced from
the equation (1) in every case in which x — a does not ab-
solutely vanish, or in which the value of x differs from the
quantity a, however small that difference may be; that since
it holds good when z is taken as nearly equal toa as we please,
and is in itself continuous as 2 approaches and arrives at that
value, it is evident that, when x becomes exactly equal to a, it
will express, as in (4), that particular value of y, or of the
vanishing fraction (2), which unites in the law of continuity
observed by all its other successive values.

Having attempted, and I expect successfully, the demonstra-
tion of the principles laid down in the extracts from my essay,
without discovering them to be “ fallacious,” it now remains for
Professor Young, since the truth is our common object, either to
subscribe to my views or to point out wherein consists the inac-
curacy of the reasoning here employed; and, without any wish,
to prolong our discussion, I unhesitatingly pledge myselt to de-
vote my most respectful and candid consideration to whatever
arguments or explanations he may be pleased to offer. But it
will be useless to pursue the subject any further unless Pro-
fessor Young will enter more into the theoretical merits of the
question and make up his mind to support every general
statement with some kind of evidence.

In Professor Young’s present letter he thinks it remarkable
that I did not reflect that was as likely to be “ the symbol of
absurdity” as the symbol of multiple values, and he follows up
the same idea by observing that “* when we are operating with
equations of the first degree, containing several unknown quan-
tities, the symbol ® is, in fact, the very form which the result
usually takes when the proposed equations involve incompatible
conditions.” If, however, subjects of absurdity are not to be ab-
surdly treated, I apprehend it will not require any extraordinary
degree of reflection to be convinced of the incorrectness of such

398 Mr. Woolhouse on the Theory of Vanishing Fractions,

anotion. On the other hand, it is rather remarkable that
Professor Young did not consider that 3 was the usual symbol

of absurdity or of incompatible conditions, and that § could
never be so, in the result of an investigation logically con-

ducted. Thus, the corresponding antecedent equation to the

Oo adie hs
result x =o, when cleared of fractions, is oz =0 or 0 =0,

an equation that is very obviously satisfied without any limi-
tation to the value of z, and that cannot fail therefore to be
compatible with other equations or conditions; but the cor-
responding antecedent equation to the result «= 2 is: =m.
an equation evidently indicating the presence of absurdity or
of incompatible conditions, unless the nature of the inyestiga-
tion will admit of infinite results.

The query respecting the geometrical series is dismissed at
once by a reference to the fourth extract from my essay. By
putting for S the series it represents, the equation is

9 n—1 a (r” — 1)
atar+ar-+.....+t ar o> Sree

and as the left-hand member is not discontinuous when 7 = 1,
the vanishing fraction, which forms the right-hand member,
must be limited to its continuous value, viz. 2a. The very
circumstance of the equation involving both a determinate
and an indeterminate quantity, when r =1, indicates the ex-
istence of a fallacy in the process by which it has been de-
duced. We first have

SS a ar a7? foes 27 pec0sn(G)
and multiplying by r — 1, we get
(ry —1) S=ar*—a =a (r®— 1) seveee (8)

which divided by 7 — 1, gives

S = oe aa eoeeeesessce (c)

In the case 7 = 1, and ry — 1= 09, we have therefore com-
mitted the fault of multiplying by absolute nought in passing
from (a) to (6); but the equation (c) is a true deduction from
(b), for the mere placing of r— 1 in the denominator of a.
fraction is not an actual performance of division. The equa-
tion (a) becomes S =a +a +a + «3 the equation (4)
entirely vanishes, and (c) becomes S = =

After the foregoing discussion it will be needless to offer any
special observations on the obvious inaccuracy of Professor

' in reply to the Observations of Professor Young. 399

Young’s views of the ellipse question. It may, however, be
worth while to take the opportunity of adding a single remark on
an erroneous principle which he appears to entertain regarding
the general theory of analytical results. I never before heard of
theincompetency of an analytical result to afford any positive in-
formation that an investigation could admit of. It is plain that
the original equations, which express the analytical conditions
of a problem, cannot include any extraneous conditions with
those expressed in the enunciation, and that they must there-
fore comprehend, in their analytical results, every solution
that the problem is capable of receiving. The equations, how-
ever, may not include certain other implied conditions, de-
pendent on the peculiar nature of the inquiry, and therefore
may yield some additional solutions incompatible with the
conditions so implied. For instance the nature of a problem
may be such as to exclude from the results not only imaginary
values but negative values and values which fall beyond cer-
tain limits, though they will be unavoidably comprehended in
the analytical solution. ‘The exclusion of inadmissible solu-
tions, therefore, rests with the nature of the problem and not
with the forms of its analytical conditions. It is hence evident
that Professor Young involves himself ina palpable incon-
sistency, when he arrives at the fact of the ellipse question
admitting multiple solutions, by an examination of the origi-
nal analytical conditions, and at the same time alleges that the
analytical result is quite incompetent to supply that informa-
tion; for the true analytical result must necessarily present
every solution capable of satisfying the analytical conditions
from which it has been deduced. If we refer back to the na-
ture of the problem, as originally presented, which is the pro-
per source of rejective information, we perceive that the only
condition it imposes on the results is the limitation which re-
quires the coordinates xy to fall within the bounds of the
ellipse, or of the circle that represents it in the indeterminate
case.

I have thus unreservedly enumerated the principal reasons
on which I found my sincere and firm conviction of the incor-
rectness of the various statements contained in Professor
Young’s letter. To avoid the possibility of being misunder-
stood, I have also given a concise analysis of the most impor-
tant of the principles maintained in my essay ; and, in conclu-
sion, I may be permitted to add, that instead of their being
*condemnatory of conclusions which, in the works of our
ablest modern analysts, wear all the aspect of mathematical
certainty,” they establish the truth of those very conclusions
on a firmer and more intelligible basis,—that instead of. the

400 Mr. E. Solly’s father Experiments on Electric Conduction.

mere aspect of certainty, in favour of those conclusions, they
substitute certainty itself.
London, April 9, 1836.

a

LXXII. Further Experiments on Conducting Power for Elec-
tricity.* By Evwarp So.ty, Jun., Esq.

15. [* my former communication I said that I had found

iodine when solid to be a nonconductor, but I did not
describe any experiments made with it in the melted state,
This perhaps may have appeared an omission, the more so after
Dr. Inglis’s note (the contents of which had not, however, been
communicated to me,) had been appended to my paper; but I
had been advised to lose no time in describing such of my ex-
periments as were in opposition to Dr. Inglis’s statement that
“jodine is a conductor”.+ What follows now will explain
that apparent omission.

16. In all my original experiments I had found iodine to be a
nonconductor in the fluid as well as the solid state; but on the
present occasion, when I was led to repeat them by the above-
mentioned statement, I was not a little surprised to find the
iodine, when rendered fluid by heat, become a conductor.
‘That a substance acting as iodine does should not be similar
as to conducting power when fluid to what it is when solid,
(as all known substances that have been as yet examined are,
excepting only such as are electrolytes, and also perhaps the
periodide of mercury,) but should appear a conductor upon
assuming the liquid state, was so singular, and so contrary
to my previous results and preconceived views, that I was in-
duced to multiply my experiments; they continued unsatis-
factory, and they were the more so as the iodine did not
always appear a conductor but sometimes a nonconductor,
and then, when it did appear a conductor it did ina very feeble
manner, and with great uncertainty.

17. Iwas therefore led to doubt the purity of the iodine which
I was using, and this seemed the more probable as it was
from a different source from that which I had employed in
the original experiments; and in the means which I had be-
fore described for examining conducting power it was impos-
sible the wires could touch, and therefore the objection which
the use of loose wires would have introduced was avoided. In
consequence I procured some perfectly pure iodine sublimed at
a very low temperature, and ascertained that that which I had

* Communicated by the Author: see our Number for February, p. 130.

+ Lond. and Edin. Phil, Mag., No, 43. p. 129.

Mx. E. Solly’s further Experiments on Electricity. 40%

‘ been previously using contained some impurity, most probably
the iodide of iron, which is not unfrequently present in the
iodine of the shops. The pure substance which I now used
proved equally a nonconductor when fused as it had proved
to be when solid.

18. When iodine is distilled with five times its weight of
chlorate of potassa, a liquid comes over, which, according
to Wohler, is a chloride of iodine: it proved to be a very
good conductor. Its solution in xther was also a good
conductor, zther being as is well known a non-conductor.
The chloride which I used. was purified by being twice
distilled off chloride! of calcium. After the electric cur-
rent had passed, upon examining the tube which had con-
tained the chloride of iodine, I found that the one platinum
wire, or that which had been the anode, was very much cor-
roded, but still quite clean; the other, or that which had been
the cathode, was encrusted with black matter very like iodine
in appearance. So good a conductor indeed was this fluid,
that the spark of a voltaic battery was hardly visibly impaired
by interposing a small portion of it in the circuit. Great heat
was evolved during the passage of the current, so that the li-
quid soon boiled.

19. The chloride of bromine and its solutions in water and
ether were all good conductors.

20..1 prepared iodic acid by Connel’s process and then
heated it up to its boiling point. I kept it fused and boiling
for about a minute, and then allowed it to cool; by this means
more than half was decomposed and volatilized, but what re-
mained was I believe pure iodic acid. I used it immediately
after this to prevent absorption of moisture from the atmo-
sphere. I then found it a most distinct insulator when solid,
but a very good conductor when fused, so much so that a spark
might be easily taken from its melted surface. Its aqueous
solution was also a very good conductor, and when strong,
iodine was precipitated at the cathode.

21. It isvery interesting and curious that iodicacid should be-
have thus, for as in all hitherto described experiments oxygen
and iodine were both found to go to the same electrode, and
as in order to the decomposition of a body the two composing
ions must go to opposite electrodes*, it seems very unlikely that
iodic acid should be an electrolyte: besides this, it is not com-
posed of one proportional of each of its elements, which Mr,
Faraday has shown to be the case with all known electrolytest.

* Experimental Researches in Electricity, by Mr. Faraday, No. 828,—
[Lond. and Edinb. Phil. Mag., vol. y. p. 425.—Eb1r.]
+ Ibid. No. 679.—[vol. v. p. 167.]

Third Series. Vol. 8. No.48. May 1836. ie

402 Reviews, and Notices respecting New Books.

If, however, it be an electrolyte, which is very improba-
ble, it will be a proof that in the electrolyzation of a sub-
stance the evolution of the one ion depends entirely on the
nature of the other ion with which it is combined; and thus
the terms anions and cations will only be relative. If, how-
ever, iodic acid is not electrolyzed, still this experiment fur-
nishes us with another exception to the law of liquido-con-
duction * similar to the periodide of mercuryt+.

22. Unfortunately, however, iodic acid is decomposed b
the same degree of heat which is required to melt it, and the
vapours of iodine entirely prevent the acid being examined
during the experiment: it is also decomposed by almost all
substances which can be used as electrodes, and therefore the
advantage which can sometimes be taken of observing which
of the electrodes is corroded, is here of no avail. I was there-
fore quite unable to ascertain whether iodic acid was electro-
lyzed or not; but when the electrodes were immersed in the
fused acid, much stronger ebullition seemed to take place than
before.

23. It was impossible to ascertain whether the oxides of
bromine and chlorine were conductors or not, and I therefore
had not the advantage of comparing iodic acid with the bro-
mic and chloric acids.

I had at first some hopes of being able to add further ex-
periments in relation to these last described, but finding that
not in my power, I no longer delay sending the above.

7, Curzon Steeet, 15th April, 1836.

LXXIII. Reviews, and Notices respecting New Books,

On the Theory and Solution of Algebraic Equations ; with the Recent
Researches of Budan, Fourier, and Sturm on the Separation of the
Real from the Imaginary Roots of Equations: by J. R. Youna, Pro-
fessor of Mathematics in Belfast College. Souter, London.

We have more than once dwelt upon the remarkable perspicuity
; of Mr. Young’s writings. In this respect they are, one and all,
models of the very best kind for the elementary writer, and far better
adapted than any which we are acquainted with, for the purposes of
actual study. In saying this, we mean no ordinary praise ; for of all
kinds of writing on science, and especially on mathematical science,
the development of elementary principles in a perspicuous and logical
manner is the most difficult. If Mr. Young had succeeded only in
this, beyond any other author in our language, he would have achieved
much, and have effected sufficient towards a diffusion, not only of

* Exp.Res. in Electricity, by Mr. Faraday, No.402.—[Lond. and Edinb
Phil. Mag., vol. iii.]
¢ Ibid. No. 691.—[vol. v. p. 169.]

Prof. Young on Algebraic Equations. 403

mathematical knowledge, but of taste for mathematical pursuits in
the younger branches of the community, to claim the gratitude of
every sincere friend of science and of man. How many have turned
away in disgust from the illogical statements (for arguments they
deserve not to be called, nor, scarcely, even sophisms,) of the general
mass of writers on analysis, under the impression, justly entertained
so far as any impression could result from such works, that it was com-
posed of a mere set of hocus pocus triflings ! or in despair of ever ac-
quiring even a glimpse of the promised land that lay beyond the ele-
mental mountain-range, darkened as it was by the symbolical mists
in which ignorant or injudicious compilers had involved them! Not

on by easy steps, generalizing the particulars, one after another, in
a way that not only commands our assent, but interests the attention
too deeply to allow of our being turned aside from the further pursuit
of science. His algebraical reasonings are not less convincing than
those of the Euclidian logic; and the hold which the elegant formule
and elegant results he derives take upon the fancy, is not less strong
than that which his compact and unsophisticated reasoning takes upon
the understanding. So much may be said of all Professor Young’s
writings: but his present work, in addition to this, has many and pe-
culiar claims upon the attention of the mathematical world, as well as
upon the young and aspiring class of mathematical students.

From the time that our distinguished countryman Harriot trans-
posed the “ absolute term” to the same side of the equation with the
other terms, algebra has taken a new aspect,—a totally new cha-
racter. He wasthus enabled to show that an equation of the nth
degree may be compounded, from n simple equations having n roots,
which may be any numbers whatever ; and he inferred (not so illogi-
cally as has been ofter represented by foreign historians of algebra*,
and too implicitly admitted by our own,) that every equation of the
mth degree has also n roots. From that time the great problem of
algebra became the determination of those roots by a practicable pro-
cess. Certain cases of it had been already solved, so far as the fourth
degree inclusive, by more than one person ; the simple and the quadra-
tic equation at a very early period, the cubic by Tartaglia and Cardan,
and the biquadratic by Ferrari. All these were solved by exhibiting
a general formula in terms of the 2nd and 3rd roots of certain as-
signed functions of the coefficients ; and the ambition of the earlier
inquirers was to find analogous expressions for the roots of the fifth
and higher degrees. The inquiry undet this form has been altogether
unsuccessful ; and the most signal mistakes, and, in many cases, the
most ludicrous ones, have been made in the progress of such attempts.

* A lithographic specimen of a manuscript page of Harriot’s work, pub-
lished by that eminent mathematical antiquary Professor Rigaud of Oxford, in
his Supplement to the works of Dr. Bradley, sets this question quite at rest.
He distinctly understood the nature both of negative and imaginary roots.
The“ Ars Praxis Analytic,” we would add, is rather to be taken as a specimen
of Warner's power to comprehend Harriot s views, than as a standard of those
views themselves.

2T?2

404 Reviews, and Notices respecting New Books.

The problem, on the authority of very careful researches into the re-
lation that must subsist amongst the roots themselves in the com-
position of the coefficients, and the degree of the subsidiary equations
to which the algebraical expression of those relations conducts us, is
now known tobe incapable of solution by a general formula. If this
be established satisfactorily (and to our own minds it is so), the in-
quiry is ended in this direction; and the only ground to hope for a so-
lution is in the discovery of some process which shall evolve the several
roots by one continuous series of operations, figure after figure, till
either the whole of them areassigned ; or, when the roots are irrational,
till so many figures shall be assigned as are necessary for the purpose
had in view in the problem in which the equation originated *. This
was the method followed by Newton, whose sagacity led him to see the
hopelessness of a general formula of solution, if not its essential im-
possibility,—one instance amongst many of his extraordinary pre-
science of the history of science in after ages, Nor was this done after
a casual view of the subject, but after careful investigations ofits charac-
ter, as is evident from the researches which he made respecting the re-
lations between the roots and the coefficients of a literal equation—re-
searches, to the results of which, much as they have been since pur-
sued, the labours of his successors have made comparatively unimpor-
tant additions. His method of approximation, however, with which we
are now more immediately concerned, was characteristic of his great
mind, and remained till our own time, except under peculiar circum-
stances, not only the briefest, but the best that had been proposed.
Still it had its difficulties and imperfections, even after the initial figure
of a root had been found, and these were fully exposed by Lagrange
in the 5th note to his Traité de Resolution des Equations as far back
as 1798; and though they have been in some degree removed by
Mr. Horner (in the Annals of Philosophy,) and Baron Fourier (in his
Analyse des Equations Determinées,) the method is on many accounts
incumbered with difficulties that are of a serious practical nature, and
essentially inherent in the principle of the process.

A method of approximation, very elegant in theory, and though not
rapid in execution, yet free from some of the defectsincident to New-
ton’s method, was given by the celebrated analyst just referred to,
Lagrange, by which the root was exhibited in a continued fraction.
This, too, besides its practical tediousness, had other inconveniences,
several of which, by the labours of Mr. Horner, published in the An-
nals of Philosophy and the Journal of the Royal Institution, were al-
most entirely removed. Still the tediousness which is essential to its
first principle of operation is such as to render it useless in practice,
except where some very important object arises to justify the employ-
ment of the great length of time which its practice requires.

It is to Mr. Horner that we owe a simple, rapid, easy, and complete
method of continuous approximation, disencumbered of all extraneous

* The investigation is here referred to cases in which the equation is re-
duced toa rational form, as indeed are all the general conclusions which are
deduced respecting equations. A valuable dissertation on irrational or surd
equations is given by Mr, Horner in the present volume of this Journal, p. 43.

Prof. Young on Algebraic Equations. © 405

operations and symbols, and arranged in a form so condensed as ra-
ther to resemble, in appearance, the extraction of the square or cube
root of a numerical quantity, than the solution of a complete equa-
tion, but considerably less complicated than even that operation as
it is generally laid down. All the work is visible to the eye, and is
arranged in a series of columns beneath the coefficients*: and these,
step by step, formed by the multiplication of the result in one column
by a single digit, and added to the next throughout the series, till the
new subtrahend is found beneath the absolute term. By a repetition
of the same process, a new trial divisor is found and verified, and the
coefficient of a new equation, having its roots reduced by the quan-
tity brought out already, has its coefficients standing in the same
columns, instead of the original coefficients at the head. A continuance
of this simple process evolves the root, figure after figure, till the whole
of them if rational, or as many as are requisite if irrational, are de-
termined. The process, moreover, instead of becoming more com-
plicated, and the determination of the next figures more uncertain,
becomes more simplified in the first respect, and more certain in the
other; and the last half of the whole number of figures (save one) are
obtained by mere division. Moreover, it presents at the end of the pro-
cess, the coefficients of a new equation, which contains the remaining
roots of the original equation. It thus, whilst the root is actually as-
signed, presents us with the depressed equation simultaneously pro-
duced,—an additional advantage of the method. Nor are these all;
but our space does not allow of our entering into further particulars.

This substitution of a general method for a general formula is not,
indeed, the object after which the lovers of mere symbols have been
straining ; and perhaps such formule, though in their employment, a
hundred times the work would be required, would be more accordant
to such prejudices: nevertheless, the mathematician who looks at
the question with a philosophic eye, will see, that as this process is
requisite even in the extraction of the roots which any such formule
must involve, the search after those formule is a matter of mere tri-
fling. Though it strains at the naked gnat, it can swallow the sym-
bolized camel,—the more smoothly, the more incumbered it is with
these useless and unintelligible hieroglyphics! By the mathematician
who values a result, less by its extreme algebraical complication than
by the elegant facility of its application to the main purposes for which
the formule were devised, a method like this must be hailed as one cf
the greatest boons that has ever been conferred upon the scientific
community. Its influence will soon be felt in every department of
philosophy which involves considerations respecting mensurable quan-
tity, by whatever means the measures can be effected; and in many
cases even theories will be brought to a decisive test, the numerical
results upon which this testing depended having been hitherto in-
volved in equations which no ardour or perseverance could resolve
by any of the methods heretofore proposed.

Though this discovery was published in the Philosophical Transac-

* No letters are introduced, and the whole process is purely numerical,

406 Reviews, and Notices respecting New Books.

tions in 1819, and was immediately pirated by others, yet it has un-
accountably been neglected amongst mathematicians in general, in
England. For this we cannot, nor do we pretend to account ; but it
is unfortunate, less for Mr. Horner’s sake than for the sake of mathe-
matical science. We hope, however, that the elegant exhibition of
the principles and the processes of the method which are given in this
work by Professor Young (together with Mr. Horner’s own illustra-
tions of the subject in Leybourn’s Mathematical Repository, vol. v.,)
will have the effect of familiarizing at least the younger and more in-
quiring English mathematicians with this beautiful system of numeri-
cal solution. No work could be better calculated to produce such an
effect, and we doubt whether any (even a minor) improvement can
be made upon it as it stands in this work, and in Mr. Horner's papers.

Even amongst those who have felt disposed to do justice to Mr.
Horner’s labours, there are few, it appears to us, who are fully aware
of the extent of the applicability of his theorems. He has, indeed,
only applied them in one particular direction ; and it is, perhaps, too
much to expect that others will be hasty in making applications of
them which he has not suggested. The unaccountable neglect with
which his past labours have been received, may well discourage the
most ardent and persevering mind. We sincerely trust, however, that
he has yet many years of activity and usefulness before him, and that
he may still be able to accomplish some of the purposes, to which his
previous investigations directly lead.

As in the extraction of the square and cube roots, so in this gene-
ral evolution of the roots of an equation, the first figure is to be
found tentatively ; and as in them, so here, the successive figures are
determined with greater certainty at every successive step. The divi-
sional portion also of neither one nor other commences till after the
first step: or in other words, the initial figure of the root and its sign
are required as a separate and preparatory step to the operation of
the method. The difficulty of effecting this first step has always been
found to be great. Lagrange proposed a method which, though theo-
ertically perfect, was yet, from the immense labour which it involved,
utterly incapable of application to practice, except, indeed, in cases in
which the necessity for its application was partially superseded by other
methods, namely, in the equations of the first four degrees *. It was
reserved for Budan to overcome this difficulty in his Nowyelle Méthode,
published in 1803, with the high approbation of Lagrange himself,
Most unaccountably, this valuable work lay neglected in France till
after Navier’s publication of Fourier’s Anal. des Eq. Det. in 1831, and
in England till it was made known to the readers of our Magazine
and of Leybourn’s Repository by Mr. Horner. It was soon perceived

* Common justice requires that the laborious researches of the Abbé de
Gua (Meém. de l’ Acad., 1741) should not be overlooked in any history of
this problem. Though only in a very limited degree successful, he yet
opened the road of inquiry, and deduced several very important results, In
his expression for the nwmber of conditions necessary to render all or any
number of the roots of an equation real, he is certainly wrong; but this is
not the place to discuss the source of his error, or to give the true formula.

Prof. Young on Algebraic Equations. 407

by the Continental mathematicians that Fourier’s was but a slight mo-
dification of Budan’s method, and accordingly the French elementary
writers since that time have invariably given the name of Budan, not
that of Fourier, to the method. The few English mathematicians who
have spoken on the subject, following Navier and Fourier, or rather
Mr. Peacock’s account of the matter, have designated them as ‘‘ Fou-
rier’s rules.” Professor Young ascribes them rightly to Budan ; and we
hope that, as his work must of necessity obtain an extensive circulation,
the mistake will be gradually corrected. We hope it is not too late,
though we well know how difficult it is to eradicate a familiar epithet,
however unjust ; as, for instance, in the case of “ Cardan’s Rule” for
cubics, and “ Mercator’s Projection” of the Sphere, neither of which,
it is well known, was the invention of the persons whose names they
bear, whilst the names of their authors, Tartaglia and Wright, are
almost unknown, except to well-read mathematicians. This rule was
an immense advance in the progress of actual solution, as it enables
us to discover the number of roots which lie between any assigned
limits, a and b, and to determine whether they be real or imaginary.
The initial (or, if need be, any number of figures,) of the real roots
may be successively determined ; and hence the methods of actual ap-
proximation, whether that of Newton, of Lagrange, or of Horner, may
be immediately commenced, and the determination of it gradually
and systematically effected*. This method, however, though in com-
parison of Lagrange’s “ Equation of the Squares of the Differences
of the Roots” such as to induce any one to rejoice in its discovery,
and value it as perfect, still a simpler, more direct, and effective me-
thod has been since discovered by M. Sturm, already alluded to. It
was read to the French Institute in 1829, before the publication of
Fourier’s Traité, but was not published in its Mémoires till a few
months ago. It was, however, printed in Crelle’s Journal fiir die
reine und angewandte Mathematik, about a year after, and was
introduced in an abridged form into the works of Lacroix, Bourdon,
and Lefebre de Fourcy, soon and successively. No allusion to it,
however, appeared in any English work till the publication of Profes-
sor Young's treatise. It is the more extraordinary that Mr. Pea-
cock should have overlooked it when writing his “ Report”, as it was
so easy of access from so many quarters, The memoir has since been
accurately and elegantly translated into English, as we noticed in a
late Number, by Mr. W. H. Spiller. The best and most simple of all
the abstracts of this important paper that we have seen is that of Mr.
Young, in the work before us. Mr. Horner has well termed it the
« gem of the book,”—well, as modestly coming from him ; but still, to
our thinking, not more a gem than the version of his own methods in
the same work : and to follow the metaphor, we would add that it is
here cut, polished, and set in the most tasteful and elegant manner
of which it seems capable. Even to accomplished mathematicians, to
whom the subject is new, we strongly recommend the reading of
Mr. Young’s chapter before taking up the original memoir, as it will

* Fourier employs the Newtonian, though he has put it in almost the
worst form, perhaps, of which it is susceptible for actual working.

408 Reviews, and Notices respecting New Books.

greatly facilitate the study of Sturm’s details to have Young’s general
view of its essential parts already in the mind: to younger and less
experienced students this course is indispensable, whilst to those who
are but arrived at the threshold of the subject, by their previous ac-
quirements, no inducement to pursue the obvious and natural course
is necessary. The process itself is, we may add, in application, only
the method of finding the greatest common measure of two alge-
braical expressions.

The real roots, both positive and negative, being successively evolved,
an equation is left in which all the roots are imaginary. For all the
purposes of actual calculation, the problem then is perfectly solved.
Still, for many reasons, it is desirable to be able to assign the quad-
ratic factors of which the depressed equation is composed. Is it too
much to hope that another Horner or another Sturm may rise up in
our own day to render the solution, in every sense, complete ?

The process of Sturm is the same as that which leads, in the usual
operation itself, to the detection of the equation which is composed of
equal roots, and terminates there at once, so that we cannot but detect
them as we proceed. This is a great advantage, in as much as we can-
not pass over this circumstance unknowingly. We have, it is true, to
depress the equation, and proceed anew ; but we have removed all am-
biguity as to equal roots, and done very much towards their determi-
nation. This advantage is peculiar to the method of Sturm. If real
roots, in the reduced equation, lie between narrow limits, we know
they are not equal ones, and therefore proceed to their separation
with certainty.

We would not, however, conceal from our readers the fact that,
advantageous as Sturm’s rule generally is, in comparison with that
of Fourier and Budan, still the great facility with which the derived
polynomes are formed in the latter method, compared with the tedious
calculations which the former often requires, is a great and decided
advantage in this stage of the work. Wherever, from the want of
some visible relation amongst the coefficients of the given equation
existing, it is probable that the derivation of Sturm’s V,, V,, etc. (or
X,, X,, etc. of Young’s notation) will give high numbers as coefficients
of these derived polynomes, we think it better to defer the application
of either method, till, by successive substitutions in the usual manner,
it is rendered evident that some test will be required, by the appear-
ance of “a doubtful interval.” Should there be but one such doubt-
ful interval, or even a small number of them, compared with the de-
gree of the equation, then we think Fourier’s method will be the less
operose: but if several, then unquestionably it will be most simple
to have recourse to Sturm’s in preference to the other. The direct-
ness of Sturm’s process, and the less danger of interchanging the ad-
ditive and subtractive signs of the result, is an advantage, however,
which furnishes great relief to the attention during the operation, and
which, to calculators who are not in the almost daily use of either the
one or the other, will be duly valued as an important feature of this
process. It may, moreover, often be abbreviated in practice by
using only a few of the higher places of figures, instead of all

Prof. Young on Algebraic Equations. 409

which result from finding the coefficients of the derived polynomes ;
as the ratios alone are sought, and these can hardly ever be required
to extreme exactness, since the general character, not the particular
values, are generally sought. Atthe same time some experience, and
the foresight which experience alone can give, is requisite to distin-
guish when, and under what circumstances, this abbreviation can be
used with perfect safety. If we take, for instance, the biquadratic
equation 32 2* + 41 2° — 184 2* — 24x + ] = 0, the application of
Sturm’s method brings us to products (and in these cases logarithms
cannot be used with perfect safety, except where the contractions can
be used) of szrteen figures; and as the coefficients of equations which
arise out of any inquiry to which algebra may be made subservient,
and under all conditions of the data, are generally less likely to be so
simple as the example given above, some subsidiary methods of less-
ening the actual trouble are yet not only desirable, but necessary.
Cannot Mr. Horner so apply or modify his principle of “ Synthetic
Division”’, as to furnish a more direct and easy algorithm for Sturm’s
Rule? We think we see more than one way by which this may be
accomplished ; but we leave it in better hands, when we refer over the
problem into his*.

The space which we can devote to a review will not allow us to
give even a general analysis of Professor Young’s treatise. It is suf=
ficient to say that it contains all that can be interesting to the student
on the subject of equations, developed with his usual perspicuity and
elegance ; and that it is brought, in all essential points, to the state of
Science at the present hour ; and though principally intended for the
use of students who have only mastered the first principles of algebra,
and happily adapted to their wants, yet as a syllabus for recalling to
the minds of the most extensively read mathematicians on the subjects
of equations, the essentials of what they already know, we are per-
suaded that it will be of considerable utility. With this conviction
we take our leave of the work, happy if our favourable notice shall be
the means of rendering it more extensively known, and that less for
the sake of Professor Young than of the numerous persons who may
derive advantage from his labours.

* We have often wondered that the method of working with the “ de-
tached coefficients” in algebraic multiplication and division has never been
introduced into practice, and even into elementary works: and that the
beautiful contrivance of what its inventor has called “ Synthetic Division”
(see Leybourn’s Repos., vol. v.,) has not also become a school-boy practice
ere now. This is also one amongst the many valuable improvements in
algebra and arithmetic conferred on mathematicians by Mr. Horner. The
eleventh edition of Hutton’s course, edited by Dr. Gregory, is the only e/e-
mentary work in which it has yet appeared,

410 Reviews, and Notices respecting New Books.

Herretotocia Mexicana, seu Descriptio Amphibiorum Nove Hispa-
nie, que itineribus Comitis de Sack, Ferdinandi Deppe et Chr, Guil.
Schiede in Museum Zoologicum Berolinense pervenerunt. Pars I.
Saurorum Species amplectens, adjecto Systematis Saurorum Pro-
dromo, additisque multis in hunc Amphibiorum ordinem observatio-
nibus, edidit Dr. Arend Friedericus Augustus Wiegmann. Accedunt
tabule lithographice decem, novorum generum typos exhibentes.
Berolini sumptibus C. G, Liideritz, 1834. London, W. Wood,
Tavistock-street.

This Work is intended to form two volumes, of which the first con-
tains the order Sauri, and the second will contain the Ophidii, Chelonii,
and Batrachii. The author treats of the Sauri, on which he has
founded the Prodromus of his system, at large, giving careful charac-
teristic definitions of all known genera, appending the Crocodiles
(Loricati, Merr.) and the Amphisbenoides, as he has done in a former
work (Handbuch der Zoologie, Berlin 1832), as aberrant suborders.
The anatomical characters of the typical subdivision (Squamati) and
of both the aberrant (Loricati and Annulati) are investigated at length.
The typical subdivision (Squamati) is divided into the series Lepto-
glossi, Rhiptoglossi,and Pachyglossi,which are developed in a Synopsis.
The central group is formed by the Chameleontes alone ; the Leptoglosst
and Pachyglossi form the lateral divisions, and are subdivided into two
sections.

LEPTOGLOSSI. RuIPTOGLOSSI. PacnyYGLosslI.

Sect. I. (aberrans.) Sect.II. (typica.) Sect. I. Sect.I. (typica.) Sect. II. (aberrans. )
(a.) Brevilingues. (b.) Fissilingues. Vermilingues. (b.) Crassilingues. (a.) Latilingues.

(Agame.)
Fam. Fam, Fam. ‘am, am.
1. Lacertz. 1. Monitores. Chamzleontes. 1. Dendrobate. Ascalabote.
2. Stychopleuri. 2. Trachydermi. 2, Humivage.
3. Chamzsauri, 8. Ameive.

4. Scinci.
5. Gymnophthalmi.

The families of the aberrant sections inhabit both hemispheres,
those belonging to the typical only one, or the tribes belonging to
the Old and New World show at least a great difference in their den-
tition. The families are well characterized according to the pecu-
liarities of their outward form and their osteological peculiarities.
The author has added several observations to the genera, and has
described a great number of new genera and species from all parts of
the world. He refers, in describing the four last families of the Brevilin-
gues, to a Synopsis of the genera, In the description of the Sauri of
Mexico, which begins at p. 22, all the living genera are described
with great accuracy, and he has often given a complete view of the
anatomy of the typical species, also a Conspectus of all the species
of the genus, with short diagnoses and descriptions of the Mexican
species. The author has also endeavoured to show their relation to
those from other parts of the world. The coloured plates surpass
those of Wagler in accuracy, and give not only a true copy of the
scaly covering of the animal, but so represent their habit and phy-
siognomy, that they appear to be drawn after living specimens.

Reviews, and Notices respecting New Books. 411

Frora Merropouitana; or Botanical Rambles within Thirty Miles
of London. Being the results of numerous Excursions madein 1833,
1834, 1835, furnishing a List of those Plants that have been found
on the different Heaths, Woods, Commons, Hills, &c., surrounding the
Metropolis (more particularly in the Counties of Surrey and Kent,)
chiefly from actual Observation and the latest Authorities. Intended
for the Student in practical Botany: with a List of the Land and
Fresh-water Shells of the Environs of London. By Daniel Cooper,
London: S. Highley, 32, Fleet street.

After a long, wet, and dismal winter, in the dirt and smoke and noise
of the City, there is something inspiring in the title of this little work,—
“ Botanic Rambles within Thirty Miles of London.” At sight of it the
sky seems at length to brighten, the air becomes mild, and our ima-
gination carries us to many a delightful spot as we glance over the
habitats which Mr. Cooper has recorded. Nor will the botanist of the
provinces smile at his brethren in the Capital when they exult in the
opportunities which are afforded them for their favourite pursuit,
if he considers the beauty and variety of the country within a cir-
cuit of thirty miles of London, and the innumerable means of con-
veyance ready at every moment of leisure or fine weather to trans-
port them to the scene of their investigations. Of this district also, how
considerable is the portion in which Nature has maintained her un-
disturbed sovereignty in spite of inclosure-acts, corn-laws, and those
artificial prices which have too often brought the crooked ploughshare
to violate tracts that mock at cultivation ; but which, when unappro-
priated and unperverted, used to yield spontaneously a rich feast to
our nobler appetites! The lover of heath and thicket and forest,
down and marsh and wood, gliding stream, and shady lane, may
certainly go further and fare worse ; nor will the pedestrian gene-
rally meet with more comfortable and reasonable entertainment
than the inns within this circuit afford. To all these advantages
we may now add that London possesses admirable schools for re-
gular botanical instruction, since that important step in our social
progress, the foundation of the University of London, and the con-
sequent establishment of King’s College: here the labours of such
eminent botanists as Professors Lindley and Don cannot fail to
be attended with extensive usefulness, not to mention other meri-
torious teachers connected with our medical schools. Highly valu-
able, however, as such aids unquestionably are, Botany, as Pro-
fessor Martyn has well observed, “ is not to be learned in the closet;
you must go forth into the garden or the fields, and there become fa-
miliar with Nature herself,—with that beauty, order, regularity, and
inexhaustible variety which is to be found in the structure of vegeta-
bles, and that wonderful fitness to its end which we perceive in every
work of creation.” It has also been justly said by another writer,
that “ the plants which adorn and characterize a picturesque country,
impressed on the recollection by that attention which the botanist is
led to bestow on them while enjoying his rambles, contribute largely
to the stock of delightful associations which he carries away with him,

412 Proceedings of Learned Societies.

and often call up the remembrance of the scenes in which he observed
them. And in the intervals of rest, or of unfavourable weather, he
may furnish himself with agreeable occupation in examining such as
are new to him.”—Flora Vectiana, Pref.

As the season has we trust arrived when we may exclaim, in the
words of the Royal Botanist,

Lo, the winter is past,

The rain is over and gone.

The flowers appear on the earth,

The time of the singing of birds is come:

we shall gladly recommend this little volume to those who are dis-
posed to connect the study of nature with the purest enjoyment.
Both what it contains and what it lacks may give them pleasing
occupation, especially if they will endeavour to supply Mr. Cooper
with contributions for a new edition. And if they would add to their
pleasure by giving some attention to a kindred pursuit, we shall re-
commend to them another companion in their excursions : namely,

The Entomologist’s Useful Compendium; or an Introduction to the
Knowledge of British Insects ; comprising the best Means of obtain-
ing, preserving, studying, and arranging them; with a Calendar of
their times of appearance, &c., illustrated with Plates: Part I.
Longman and Co.

The publication has been seasonably commenced in monthly parts,
each part containing, in addition to a portion of the work, a Calendar
of the times of appearance of insects for the ensuing month, the places
where they may usually be found, and directions for collecting them,
which will afford great assistance to the student.

The merits of the work are well known from the former edition,
which was soon exhausted ; and Mr. Samouelle has been long en-
gaged in improving it, and adapting it to the advanced state of natural
history.

LXXIV. Proceedings of Learned Societies.

ROYAL SOCIETY.
[Continued from p. 156.]

Dec. Jy lap following papers were read : “Memoranda taken

1835. during the continuance of the Aurora Borealis of
November 18, 1835.” By Charles C, Christie, Esq. Communi-
cated by Samuel Hunter Christie, Esq., F.R.S.

The appearances described were seen from Deal, on the day men-
tioned in the title, from 9 to 20 minutes past 10 o’clock in the even-
ing ; and consisted chiefly of a bright arch of light, of which the
lower edge was sharply defined, surmounted on a dark cloud below,
while the upper edge was shaded off into the cloudless and starlight
sky, emitting large but faint luminous streaks, which issued up-

Royal Society. 413

wards with great rapidity, exactly imitating flames agitated to and
fro by a violent wind.*

««Démonstration compléte du Théoréme dit de Fermat: par
Fran¢ois Paulet, de Genéve, ancien éléve de l’E’cole Polytechnique.”
Communicated by P. M. Roget, M.D., Sec. R.S.

The theorem of which the author professes to give, in this paper,
the complete demonstration, is the following: ‘No power, beyond
the second degree, of any quantity, can exist, capable of being re~
solved into the sum, or the difference, of two other powers of the
same degree :” or, as it may still more generally be expressed, “ If
the exponents of three powers be multiplied by the same number,
provided that number be greater than 2, neither the sum, nor the
difference, of any two of the resulting quantities can ever be equal
to the third quantity.”

Dec. 17.—“ Researches towards establishing a theory of the
Dispersion of Light, No. II.’ By the Rev. Baden Powell, M.A.,
F.R.S., Savilian Professor of Geometry in the University of Oxford.

The author, in a preceding paper, published in the last part of
the Philosophical Transactionst, commenced a comparison between
the results of M. Cauchy's system of undulations, expressing the
theoretical refractive index for each of the standard rays of the
spectrum, and the corresponding index found from observation in
different media. Since that paper was communicated, he has re-
ceived the account of a new series of results obtained by M. Rud-
berg, and comprising the indices for the standard rays in a prism of
calcareous spar, and in a prism of quartz, both for the ordinary and
the extraordinary rays; and also the ratios of the velocities in the
direction of the three axes of elasticity, respectively, in Arragonite
and Topaz. The author was accordingly led to examine this valu-
able series of data, and the comparison of them with the theory forms
the subject of the present paper. He finds the coincidences of theory
and observation to be at least as close as those already obtained from
Fraunhofer’s results, and to afford a satisfactory extension of the
theory to ten new cases, in addition to those already discussed ; and
a further confirmation of the law assigned by the hypothesis of un-
dulations.

A paper was in part read, entitled, “‘ On the action of Light upon
Plants, and of Plants upon the Atmosphere.”” By Charles Daubeny,
M.D., F.R.S., Professor of Chemistry and of Botany in the Univer-
sity of Oxford.

Jan. 7, 1836.—A paper was read, entitled, «‘ Meteorological Jour-
nal kept at the Royal Observatory, Cape of Good Hope, from the
1st of June to the 3lst of December, 1834.” Communicated by
Capt. Beaufort, R.N., F.R.S., Hydrographer to the Admiralty.

* Other particulars respecting this Aurora have been given in our late
Numbers: by Mr. Sturgeon, p. 134; Dr. Robinson, p. 236; and Prof. Rigaud,
p- 850.—Ebpir.

+ An abstract of Prof. Powell’s preceding memoir will be found in Lond.
and Edinb. Phil. Mag., vol. vi. p. 374: various papers on the subject, by-Prof.
Powelland Mr. Tovey, have appeared in our last and present volumes.—Eprr.

414 Royal Society.

The observations recorded in this Journal are those of the baro.
meter, and of two thermometers, one in, and the other out of doors;
taken at sunrise, noon, sunset, and midnight, in each successive day
from the Ist of June, 1834, to the end of the year.

«« Some Account of the Volcanic Eruption of Coseguina in the
Bay of Fonseca, commonly called the Coast of Conchagua, on the
Western Coast of Central America.” By Alexander Caldcleugh,
Esq., F.R.S.

The particulars recorded in this narrative are derived partly from
a voluminous collection of official reports transmitted from the au-
thorities in various towns to the government of Central America,
_ and partly from the information of intelligent eye-witnesses of the
phenomena. The eruption occurred on the 19th of January, 1835,
and was preceded by a slight noise, accompanied with a column of
smoke issuing from the mountain, and increasing till it took the form
of alarge and dense cloud, which, when viewed from a distance of ten
leagues to the southward, appeared like an immense plume of white
feathers, rising with considerable velocity and expanding in every
direction. Its colour was, at first, of the most brilliant white; but
it gradually became tinged with grey; then passed into yellow; and
finally assumed a beautiful crimson hue. In the course of the fol-
lowing days several shocks of an earthquake were felt, the last of
which were most terrific. On the morning of the 22nd, the sun had
risen in brightness; but a line of intense darkness denoted the pre-
sence of the same cloud which had before presented such remarkable
appearances, and which, extending with great rapidity, soon ob-
scured the light of day ; so that in the course of half an hour the
darkness equalled in intensity that of the most clouded night: per-
sons touched without seeing one another ; ‘the cattle hurried back
to their folds ; and the fowls went to roost, as on the approach of
night. This atmospheric darkness continued with scarcely any di-
minution for three days; during the whole of which time there fell
a fine impalpable dust, covering the ground at St. Antonio to the
depth of two inches and a half, and consisting of three layers of
different shades of grey colour: and for ten or twelve succeeding
days the sky exhibited a dim and murky light. At Nacaome, to
the northward of the volcano, the same degree of darkness was ex-
perienced, and the deposit of ashes was from four 'to five inches in
depth, and exhaled a fetid sulphureous odour, which penetrated
through every interstice in the buildings. The complete obscurity
was only occasionally broken by the lightning, which-flashed in every
direction, while the air was rent with loud and reiterated explosions
like the discharges of artillery, which accompanied each eruption of
volcanic matter, and conspired to strike the deepest terror, and to
spread among the inhabitants a universal panic that the day of judge-
ment was arrived. On the 24th the atmosphere became clearer, and
the houses were found covered to the depth of eight inches with ashes,
in which many small birds were found suffocated. Deer and other
wild animals flew to the town for refuge, and the banks of the neigh-
bouring streams were strewed with dead fish. In Segovia, and as
far as eight leagues from the volcano, the showers of black sand were

Royal Society. 415

so abundant as to destroy thousands of cattle; and many were
subsequently found whose bodies exhibited one mass of scorched
flesh.

Within the Bay of Fonseca, and two miles from the volcano, it is
stated that two islands, from two to three hundred yards in diameter,
were thrown up, probably from the deposit of masses of scoriz on
previously existing shoals.

Jan. 14.—Dr. Daubeny’s paper entitled, “ On the action of Light
upon Plants, and of Plants upon the Atmosphere,” was resumed and
concluded.

The objects of the experimental inquiries of which the author gives
an account in this paper were, in the first place, to ascertain the ex-
tent of the influence of solar light in causing the leaves of plants to
emit oxygen gas, and to decompose carbonic acid, when the plants
were either immersed in water, or surrounded by atmospheric air.
The plants subjected to the former mode of trial were Brassica
oleracea, Salicornia herbacea, Fucus digitatus, Tussilago hybrida, Co-
chlearia armorica, Mentha viridis, Rheum rhaponticum, Allium ur-
sinum, and several species of Graminee. Geraniums were the only
plants subjected to experiment while surrounded with atmospheric
air. Comparative trials were made of the action on these plants of
various kinds of coloured light, transmitted through tinted glass, of
which the relative calorific, illuminating, and chemical powers had
been previously ascertained ; and the results of all the experiments
are recorded in tables; but no general conclusion is deduced from
them by the author. He next describes a few experiments which
he made on beans, with a view to ascertain the influence of light on
the secretion of the green matter of the leaves, or rather to deter-
mine whether the change of colour in the chromule is to be ascribed
to this agent. The third object of his inquiries was the source of
the irritability of the Mimosa pudica, from which it appeared that
light of a certain intensity is necessary for the maintenance of the
healthy functions of this plant, and that when subjected to the ac-
tion of the less luminous rays, notwithstanding their chemical influ-
ence, the plant lost its irritability quite as soon as when light was
altogether excluded. He then examines the action of light in causing
exhalation of moisture from the leaves; selecting Dahlias, Helian-
thuses, Tree Mallows, &c., as the subjects of experiment. The
general tendency of the results obtained in this series is to show that
the exhalation is, ceteris paribus, most abundant in proportion to the
intensity of the light received by the plant. He also made various
comparative trials of the quantity of water absorbed, under dif-
ferent circumstances, by the roots of plants, and chiefly of the He-
lianthus annuus, Sagittaria sagittifolia, and the Vine. From the ge-
neral tenor of the results of these and the preceding experiments, he
isinclined to infer that both the exhalation and the absorption of
moisture in plants, as far as they depend on the influence of light,
are affected in the greatest degree by the most luminous rays ; that
all the functions of the vegetable economy which are owing to the
presence of this agent, follow, in this respect, the same law; and
that in the vegetable, as well as in the animal kingdom, light acts in

416 Royal Society.

the character of a specific stimulus. The author found that the
most intense artificial light that he could obtain from incandescent
lime produced no sensible effect on plants.

The latter part of the paper is occupied by details of the experi-
ments which the author made with a view to ascertain the action of
plants upon the atmosphere, and more especially to determine the
proportion that exists between the effects attributable to their action
during the night and during the day; and also the proportion be-
tween the carbonic acid absorbed, and the oxygen evolved.

His experiments appear to show that at least 18 per cent. of oxy-
gen may be added to the air confined in a jar by the influence of a
plant contained within it. He also infers that the stage of vegetable
life at which the function of purifying the air ceases, is that in which
leaves cease to exist. The author shows that this function is per-
formed both in dicotyledonous and in monocotyledonous plants, in
evergreens as well as in those that are deciduous, in terrestrial and
in aquatic plants, in the green parts of esculents as well as in ordinary
leaves, in Alge and in Ferns as well as in Phanerogamous families.
Professor Marcet has shown that it does not take place in Fungi*.

The reading of a paper, entitled, ‘« On the Anatomical and Optical
Structure of the Crystalline Lenses of Animals, being the continua-
tion of the paper published in the Philosophical Transactions for
1833.” By Sir David Brewster, K.H., LL.D., F.R.S.,—was com-
menced.

Jan, 21.—Sir David Brewster’s paper, entitled, “On the Anato-
mical and Optical Structure of the Crystalline Lenses of Animals,
being the continuation of the paper published in the Philosophical
Transactions for 1833,” + was resumed and concluded.

The author has examined the structure of the crystalline lens of
the eye of a great variety of animals belonging to each of the four
classes of Vertebrata; and has communicated in this paper a de-
tailed account of his observations, arranged according as they re-
late to structures more and more complex. In a former paper,
published in the Philosophical Transactions for 1833, the lens of the
Cod fish was taken as the type of the simplest of these structures, in
as muchas all the fibres of which it is composed converge, like the
meridians of a globe, to two opposite points, or poles, of a spheroid
or lenticular solid ; both of which poles are situated in the axis of
vision. The structure which ranks next in respect of simplicity is
that exhibited in the Salmon, among fishes; in the Gecko, among
reptiles; and in the Hare, among Mammalia. It presents at each pole
two septa placed in one continuous line, in different points of which
all the fibres proceeding from the one surface to the other have their
origin and termination. A structure somewhat more complex is
met with in the lenses of most of the Mammalia, and is particularly
exemplified in the lion, the tiger, the horse, and the ox. Three
septa occur at each pole in the form of diverging lines inclined to

* A notice of the results obtained by Prof. Marcet will he found at p. 82
of the present volume.—Enpir.

+ Sir D. Brewster’s former paper on this subject was given entire, with
additions, in our Number for March last, p. 193.—Epir.

Royal Society. 417

one another at angles of 120°. The next degree of complexity is
presented in the lens of the whale, the seal, and the bear, which
contain, instead of three, four septa on each side, placed at right
angles to each other in the form of across. In some specimens of
lenses of whales and seals the author observed two septa from each
pole, forming one continuous line, from each of the extremities of
which proceeded two others, which were at right angles relatively to
one another: so that there were in all five on each surface. The
most complex structure is that of the lens of the elephant, which
exhibits three primary septa diverging at equal angles from the pole,
and at their extremities bifurcating into two additional septa, which
are inclined to each other at angles of 60°, these latter being the
real septa, to which the fibrous radiations are principally related.
In some lenses of the elephant the author found the three septa
immediately proceeding from the poles exceedingly short, and ap-
proaching to evanescence ; so that he has no doubt that occasion-
ally they may be found to have disappeared, and that the other six
septa will then all diverge from the poles, like the radii of a hexagon,
at angles of 60°.

In all the preceding cases, where the arrangement of the fibres
is symmetrical on the two sides, the septa on the opposite surface
of the lens occupy positions which are reversed with respect to one
another ; thus in the simple case of the double septa at each pole,
the line formed by those of the posterior surface is situated at right
angles to that formed by the septa of the anterior surface. Where
there are three divergent septa at each pole, the direction of those
on the one side bisect the angles formed by those on the other side ;
and again, where the septa form a rectangular cross, those of one
surface are inclined 45° to those of the other surface.

It follows as a consequence of this configuration of the series of
points which constitute the origins and terminations of the fibres,
that all the fibres, with the exception only of those proceeding in a
direct line from the extremities of any of the septa, must, in their
passage from the one surface to the other, follow a course more or
less contorted ; and must form lines of double curvature; that is,
curves of which none of the portions lie in the same plane.

The fibres of the lenses of quadrupeds gradually diminish in size
from the equator or margin of the lens, where they are largest, to
their terminations in the anterior or posterior septa. They are
united together by small teeth like those of fishes; but, generally
speaking, the teeth are smaller and less distinctly pronounced, and
sometimes they are not seen without great difficulty.

In the lens of the turtle, as well as in that of several fishes, the
arrangement of the fibres, instead of being symmetrical on the two
sides, as is the case in all the preceding instances, is different on the
anterior and posterior surfaces; there being two septa on the for-
mer, but none in the latter, which presents only a single polar point
of convergence.

The author has directed much of his attention to the optical pro-
perties of these structures. Thelens of the salmon depolarizes three

Third Series. Vol.8. No. 48. May 1836. 2U

418 Royal Society.

series of luminous sectors ; the inner and outer series being negative,
and the intermediate series positive. The polarizing structure of
the cornea is negative, and it depolarizes very high tints at its junc-
tion with the sclerotic coat. When a slice cut from the sclerotica
nearly perpendicularly to the surfaces, and with parallel faces, is
exposed to polarized light, it exhibits the system of biaxal rectilineal
fringes, exactly like those in a plate of glass heated by boiling wa-
ter or oil, when in the act of rapid cooling. The same alternation
of properties with regard to polarization in the successive strata of
the substance of the crystalline lenses is exhibited by other fishes
which the author examined.

With respect to the final cause of these highly complicated ar-
rangements, it is reasonable to conceive that the gradually increas-
ing density of the fibres in each successive stratum from the surface
to the centre is intended to correct spherical aberration : but the
design of the other properties resulting from the arrangement of the
fibres with reference to septa, in all their variations of number and
position, and more especially the alternations of positive and nega-
tive structures, as exhibited by the action of the different strata in
polarized light, has not even excited the ingenuity of conjecture,
and will probably remain among the numerous problems destined to
exercise the sagacity of another age.

Jan. 28.—A paper was read, entitled, “ Discussion of Tide Ob-
servations made at Liverpool.” By J. W. Lubbock, Esq., F.R.S.

The chief purpose which the author has in view in presenting the
tables accompanying this paper, which are a continuation of those
published in the Philosophical Transactions for 1835, and are
founded on the observations instituted by Mr. Hutchinson at Liver-
pool, is to exhibit the diurnal inequality in the height of high water,
which is.scarcely sensible in the river Thames, but which at Liver-
pool amounts to more than a foot. The diurnal inequality in the
interval appears to be insensible.

The author has further ascertained that Bernoulli’s formule ex-
pressing the height of the tide, deduced from his theory of the tides,
present a very remarkable accordance with observation.

Feb.4.-—“‘ Geometrical Investigations concerning the Phenomena
of Terrestrial Magnetism: Second Series,-—On the number of points
at which a magnetic needle can take a position vertical to the Karth’s
surface.” By Thomas Stephens Davies, Esq., F.R.S. Lond. and
Edin., F.R.A.S., of the Royal Military Academy, Woolwich.

This paper is intended as a continuation of the one by the same
author published in the last volume of the Philosophical Transac-
tions* ; in which it was proposed to investigate the mathematical
consequences of the hypothesis of the earth being a magnet with
two poles, or centres of force, situated anywhere either within, or
at the surface, and of equal intensity, but of contrary characters :
with the ultimate view of verifying this hypothesis by comparing its
results, so deduced, with the phenomena furnished by observation.

* An abstract of Mr. Davies’s former paper appeared in Lond. and Edinb,
Phil. Mag., vol. vi. p. 302-305.—Epir.

Royal Society. 419

In his former paper the author had shown that on this hypothesis
the magnetic equator, or the locus of the points at which the mag-
netic needJe takes a horizontal position, is one single and continuous
line on the surface of the earth. In this paper his object is to prove
that there are always two, and never more than two, points at the
earth’s surface, at which the needle takes a position vertical to the
horizon.

At the close of his former paper the author had deduced the
equation of the curve of verticity, that is, of the curve at any point
of which an infinitesimal needle being placed, it will always tend
towards the centre of the earth, and consequently be vertical to the
horizon at its point of intersection with the surface of the earth -
but, owing to circumstances over which he had no control, he was
unable, at that time, to write out an account of his investigations of
the peculiar character of that curve, or to apply its properties to the
determination of the latter problem: and these are more especially
the objects to which the present paper is devoted.

The processes to which he has had recourse, with this view, are
the following. He first transforms the rectangular equation of the
curve into a polar equation, and finds that in the result the radius
vector is involved only in the second degree; and hence that for
every value of the polar angle there are two values of the radius
vector, and never more than two ; or, in other words, that no line
drawn from the centre of the earth can cut the curve of verticity in
more than two points. But as no means present themselves of ase
certaining whether the values of (r), the polar ordinates of the curve
of contact, be always real or not, or how many values of (6), the
other co-ordinate to that curve, are possible for any given value of
7; he abandons this method of inquiry, contenting himself with a
few deductions respecting the general form of the locus, and proceeds
to employ a different method.

The general system of his reasonings proceeds on the principle
that as the magnetic curve itself, and the curve of verticity have one
common and dependent genesis, a knowledge of the properties of
the former must throw considerable light on those of the latter; and
he is accordingly induced to enter into a more minute examination
of the magnetic curve than had before been attempted. As both
the polar and the rectangular equations of this curve are much too
complex to afford any hope of success in their investigation, the
author has recourse to a system of co-ordinates, which he terms the
‘angular system,” and which was suggested to him originally by the
form under which Professor Playfair exhibited this equation in Ro.
bison’s Mechanical Philosophy. But as he has not yet published
his investigations of the differential coefficients, and other formule
necessary in the application of this system, he puts his results in
a form adapted to rectangular co-ordinates ; each rectangular co-
ordinate being expressed in terms of his angular co-ordinates and
the constants of the given equation; and by these means deduces
the characters of the magnetic curve throughout its whole course.

The angular equation being

cos 6, + cos 6,, =2cos B,
2U2

420 Royal Society.

he finds, 1°, that the two equations, the convergent and the divergent,
or that in which the poles are unlike, and that in which they are
like, are both expressed by this equation, and essentially included
in it: 2°, that the divergent branches on one side of the magnetic
axis are algebraically and geometrically continuous with the con-
vergent branches on the other side; the parameter (6) being the
same in both cases: 3°, that the divergent branches are assym-
ptotic, and the assymptote is capable of a very simple construction ;
4°, that the continuous branches have the poles as points of in-
flexion, and that these are the only points of inflexion within finite
limits: 5°, that a tangent at any point of the curve, or, which is
the same thing, the direction taken by a small needle placed there,
admits of easy construction: 6°, that when the parameter (() is
such as to cause the convergent and divergent branches to intersect,
they do so in a perpendicular to the magnetic axis drawn from the
poles: 7°, that the convergent branches are always concave, and
the divergent always convex, to a line at right angles to the magnet,
drawn from its middle,—besides other properties not less interesting,
though less capable of succinct enunciation.

Having separated the branches belonging to the case of like poles
from those belonging to the unlike ones in the magnetic curve, the
author proceeds to asimilar separation of the corresponding branches
in the curve of verticity. In the former case the curve is composed
of two branches infinite in length, having the magnetic axis for as-
symptotes, lying above that axis, and emanating from the poles to
the right and left ; and of two finite branches, continuous with those
just described, and lying below the magnetic axis; one of which
passes through the centre of the earth, and meets the other in the
perpendicular from the middle of the axis; so that the whole system
is constituted by one continuous curve, extending from negative
infinite to positive infinite, and having the lines drawn from the centre
of the earth to the magnetic poles as tangents at the poles ; and no
part of the curve lies between these tangents. It bears in form
some general resemblance to a distorted conchoid ; this curve not
having either cusp or loop. In the second case, the curve is also
composed. of four branches, two finite and two infinite ones; the
latter having the line drawn from the centre of the earth through
the middle of the magnet as assymptotes, and both lying on the
same: side of it as the more distant pole; and the finite branches
joining these continuously at the poles, and each other in the mid-
dle of the magnetic axis; the one from the nearer pole lying above
the axis, and the one from the remoter pole lying below it. The
branches, where they unite at the poles, have the lines drawn from
the centre of the earth to the poles as tangents, and the Jower in-
finite branch passes through the centre. The whole system of
branches is comprised between the polar tangents; and the two
systems are mutually tangential at the poles, and intersect each
other at the centre; but they have no other point in common.

Lastly, the author proceeds to demonstrate that a circle (namely,
the magnetic meridian) described from the centre of the curve of
verticity, will always cut the convergent system in two points, but

Royal Society. 421

can never cut it in more than two. He remarks, however, that if
we could conceive two poles of like kinds to exist without any other
whatsoever, we might have either four points of verticity, or only
two, according to circumstances ; but he waves the discussion of this
particular case, as being irrelevant to the purpose of his present
inquiry.

Mr. Davies announces his intention of shortly laying before the
Society a continuation of these researches; devoting the next series
to the points of maximum intensity.

“ Memoir on the Metamorphoses in the Macroura, or Long-
tailed Crustacea, exemplified in the Prawn (Palemon serratus).” By
John V.Thompson, Esq.,F.L.S., Deputy Inspector-General of Hospi-
tals. Communicated by Sir James Macgrigor, M.D., F.R.S., &c.

Theauthor gives descriptions, illustrated by outline figures, of three
different stages of growth of the Prawn; the first being that of the
larva immediately on its exclusion from the egg ; the second, at a
later period, when it has acquired an additional pair of cleft mem-
bers, and a pair of scales on each side of the tail ; and the third, at
a still more advanced stage of development, when it presents the
general appearance of the adult Prawn, but still retains the natatory
division of the members, now increased to six pair. The author
thinks it probable that an intermediate stage of metamorphosis exists
between the two last of these observed conditions of the animal.

Feb. 11.—A paper was in part read, entitled, “ On Voltaic Com-
binations.” Ina letter addressed to Michael Faraday, Esq., D.C.L.,
F.R.S. Fullerian Professor of Chemistry in the Royal Institution of
Great Britain, &c., &c. By John Frederick Daniell, Esq., F.R.S.,
Professor of Chemistry in King’s College, London.

Feb. 18.—The reading of Mr. Daniell’s paper, entitled, “ On Vol-
taic Combinations,” in a letter to Michael Faraday, Esq., D.C.L.,
F.R.S., &c., was resumed and concluded.

The author, after expressing his obligations to Mr. Faraday for
the important light which hislate researches in electricityhave thrown
on chemical science*, proceeds to state that in pursuing the train of
inquiry which has thus been opened, he has obtained further confir-
mations of the truth of that great principle discovered and esta-
blished by Mr. Faraday, namely, the definite chemical action of
electricity ; and has thence been led to the construction of a voltaic
arrangement which furnishes a constant current of electricity for
any required length of time.

For the purpose of ascertaining the influence exerted by the dif-
ferent parts of the voltaic battery in their various forms of combi-

* The greater part of Mr. Faraday’s Experimental Researches in Elec-
tricity will be found entire in Lond. and Edinb. Phil. Mag., vol. iii., vol. v.,
vol. vi.; and of his other Series abstracts have been given in Phil. Mag. and
Annals, N.S., vol. xi., and in the succeeding volumes of Lond. and Edinb.
Phil. Mag. Mr. Faraday’s Seventh Series, on the definite chemical action
of Electricity, appeared in Lond. and Edinb. Phil. Mag., vol. v. p. 161; and
his Tenth Series, on the construction of the Voltaic Battery, in our present
volume, p. 114,—Eprr.

422 Royal Society.

nation, he contrived an apparatus, which he designates by the name
of the dissected battery, and which consists of ten cylindrical glass
cells, capable of holding the fluid electrolytes, in which two plates
of metal are immersed ; each plate communicating below, by means
of a separate wire, which is made to perforate a glass stopper closing
the bottom of the cell, with a small quantity of mercury, contained
in a separate cup underneath the stopper, and with which electric
communications may bemade at pleasure through other wires passing
out of the vessel on each side. ‘The active elements of the circuit,
which were adopted as standards of comparison, were, for the me-
tals, plates of platinum and amalgamated zinc three inches in length
by one in breadth; and for the electrolyte, water acidulated with
sulphuric acid, in the proportion of 100 parts by volume of the for-
mer to 2-25 of the latter; this degree of dilution (giving a spe-
cific gravity of 1:0275,) being adopted, in order to connect the au-
thor’s experiments with those of Mr. Faraday.

This dilute acid exerts scarcely any local action on amalgamated
zinc ; because the surface of the metal becomes covered with bub-
bles of hydrogen gas, which adhere strongly to it; and this force
of heterogeneous adhesion appears to have an important influence
on the phenomena both of local and of current affinity, and soon
puts a stop to the decomposition of the water by the zinc. When
a small quantity of nitric acid is added to the acidulated water, the
same plate which in the former experiment resisted the action of
the diluted sulphuric acid, is, in a few hours, entirely dissolved,
without the extrication of any gaseous matter. This result is ex-
plained by the author on the supposition that the elements of the
nitric acid enter into combination with the hydrogen as it is evolved,
and that the opposing attraction of this latter substance is thus re-
moved. The author finds, in like manner, that nascent hydrogen
deoxidates copper, and precipitates it from its solutions upon the
negative plate of the voltaic circuit.

A series of experiments performed with the dissected battery is
next described ; illustrating, in a striking manner, the difference of
effects with relation to the quantity and the intensity of the electric
current, consequent on the different modes of connecting the ele-
ments of the battery: the former property being chiefly exhibited
when the plates of the respective metals are united together so as
to constitute a single pair; and the latter being exalted when the
separate pairs are combined in alternate series. The influence of
different modifications of these arrangements, and the effects of the
interposition of pairs in the reverse order, operating as causes of
retardation, are next inquired into.

In the course of these researches, the author, being struck with
the great extent of negative metallic surface over which the deoxi-
dating influence of the positive metal appeared to manifest itself,
as is shown more especially in the cases where a large sheet of cop-
per is protected from corrosion by a piece of zinc or iron of com-
paratively very small dimensions, was induced to institute a more
careful examination of the circumstances attending this class of phe-
nomena ; and was thus led to discover the cause of the variations

Linnean Society. 423

and progressive decline of the power of the ordinary voltaic battery,
one of the principal of which is the deposit of the zinc on the platina
[or copper] plates ; and to establish certain principles from which a
method of counteracting this evil may be derived. The particular
construction which he has devised for the attainment of this object,
and which he denominates the constant battery, consists of a hollow
copper cylinder, containing within it a membranous tube formed by
the gullet of an ox, in the axis of which is placed a cylindrical rod
of zinc. The dilute acid is poured into the membranous tube from
above by means of a funnel, and passes off, as occasion requires, by
a siphon tube at the lower part; while the space between the tube
and the sides of the copper cylinder is filled with a solution of sul-
phate of copper, which is preserved in a state of saturation by a
quantity of this substance suspended in it by a cullender, allowing
it to percolate in proportion as it is dissolved. Two principal objects
are accomplished by this arrangement ; first, the removal out of the
circuit of the oxide of zinc, the deposit of which is so injurious to
the continuance of the effect of the common battery ; and, secondly,
the absorption of the hydrogen evolved upon the surface of the
copper, without the precipitation of any substance which would lead
to counteract the voltaic action of that surface. The first is com-
pletely effected by the suspension of the zinc rod in the interior
membranous cell into which fresh acidulated water is allowed slowly
to drop, in proportion as the heavier solution of the oxide of zinc
is withdrawn from the bottom of the cell by the siphon tube.
The second object is attained by charging the exterior space sur-
rounding the membrane with a saturated solution of sulphate of
copper, instead of diluted acid ; for, on completing the circuit, the
electric current passes freely through this solution, and no hydrogen
makes its appearance upon the conducting plate; but a beautiful
pink coating of pure copper is precipitated upon it, and thus perpe-
tually renews its surface.

When the whole battery is properly arranged and charged in this
manner, it produces a perfectly equal and steady current of electri-
city for many hours together. It possesses also the further advan-
tages of enabling us to get rid of all local action by the facility it
affords of applying amalgamated zinc ; of allowing the replacement
of the zinc rods at a very trifling expense ; of securing the total
absence of any wear of the copper; of requiring no employment of
nitric acid, but substituting in its stead materials of greater cheap-
ness, namely, sulphate of copper, and oil of vitriol; the total ab-
sence of any annoying fumes ; and lastly, the facility and perfection
with which all metallic communications may be made and their ar-
rangements varied.

LINNZEAN SOCIETY.

April 5.—A paper was read, entitled, “ On the Ovula of Santalum
album ; by William Griffith, Esq., Assistant Surgeon in the Madras
Medical Service: communicated by R. H. Solly, Esq-, F.L.S.”

In this paper are detailed minute observations on the fecundation
of Santalum album, carried on through all the stages of that process,

424 Royal Society of Edinburgh.

and throwing additional light on the subjects investigated by Mr.
Brown, in his papers on the Sexual Organs and mode of Impregna-
tion in Orchide@ and Asclepiadee, of which abstracts were given in
Phil. Mag. and Annals, N.S., vol. x. p. 437; and Lond. and Edinb.
Phil. Mag., vol. i. p. 70.

A paper was also read, containing particulars of the lives of the
two eminent botanists of the early part of the last century, named
Sherard,—especially of William Sherard, who founded the Professor-
ship of Botany at Oxford which bears his name,—and of Dillenius,
who was appointed the first professor upon that foundation ; derived
from the papers of the celebrated Peter Collinson, and communicated
to the Society by Aylmer Bourke Lambert, Esq., V.P.L.S.

William Sherard was appointed English consul at Smyrna, where
he made large collections of plants, which he brought to England
with him, and with the assistance of his brother, James Sherard,
commenced the preparation of his Pinax. James Sherard afterwards |
became possessed of a botanical garden at Eltham, in which he cul-
tivated the plants of the Hortus Elthamensis.

It is mentioned as a point of some curiosity, that Dillenius, though
attached to the study of mosses, which are among the most diminu-
tive of plants, was himself “ tall and clumsy.” Notices are alse given
of Catesby, author of the “Natural History of Carolina ;”” among these
it is stated that the plates illustrating the works of both Dillenius and
Catesby were all drawn as well as engraved by the authors themselves,
and the works produced under circumstances of great discouragement.

ROYAL SOCIETY OF EDINBURGH.

Feb. 15.—The award of the Keith Prize to Professor Forbes having
been announced by the Council on the 18th of January, the medal
was presented by Dr. Hope, the Vice-President in the Chair, ac-
companied by an address to the following effect.

The prize founded by ourlate estimable associate Mr. Keith, whose
ingenious contrivances for self-registering thermometers and baro-
meters are recorded in our Transactions, is, by the regulation of his
Trustees, to be adjudged biennially for the most important discovery
communicated to the Royal Society, or in the event of such being
wanting, for the best paper which shall have been presented to the
Society in the space of two years on ascientific subject. The Coun-
cil, in discharge of the powers vested in them, have awarded unani-
mously the Keith prize for the last biennial period, to Professor
Forbes, for his paper ‘‘ On the Refractionand Polarization of Heat,”
which they consider to come under that class of communications,
which contain discoveries important to science.

The Vice-President then observed, that the subject of heat is one
so important to man, and so intimately connected with a variety of
natural phenomena, that it has not failed to command a great de-
gree of attention in all ages:—That an intimate connexion subsists
between Heat and Light, and that much discordance of opinion has
subsisted respecting the nature of both. He next stated the various
opinions entertained concerning them, and particularly respecting

Refraction and Polarization of Heat. 425

heat, and in historic order presented the views of Bacon, Boyle,
Boerhaave, Stahl, and Black, and adverted to the discoveries of
Black respecting latent and specific heat, and the successive labours
of Irvine, Crawfurd, Wilke, Magellan, Lavoisier and Laplace, Dulong
and Petit, in the same field.

Heat presents itself in two very different conditions ; first when
combined with matter, pervading bodies slowly, either by commu-
nication and conduction through and among its particles, or by the
movements of the particles themselves; secondly, when radiated,
moving through elastic fluids or empty space with vast velocity.

The first of these had been studied by the philosophers already
named, and not long after by Rumford. To the second of these, viz.
radiant heat, the subject of Professor Forbes’s discovery called upon
him more especially to allude, and to present a brief historic view.

The radiation of cold, and its reflection by metallic mirrors, was
known to Baptista Porta in the sixteenth century ; and observations
were made on the radiation of heat, by the Florentine academicians,
towards the middle of the seventeenth century, and by Marriotte in
1682. About the middle of the 18th century, Lambert published
his works on pyrometry and photometry, which contained some of
the first accurate experiments on this subject ; and the facts of the
difficult transmission and reflection of heat by glass, were pointed
out by the Swedish chemist Scheele. Pictet of Geneva extended
his experiments on the radiation and the reflection of the heat de-
rived from boiling water; and our venerable associate Professor Pre-
vost of the same place, established the doctrine of the mobile equi-
librium of heat, in 1802. The triumph of this theory was found in
the beautiful experiments of Dr. Wells, on dew, in 1813.

Meanwhile, the experiments of Rumford and Leslie were corro-
borating and extending these general views, even although the doc-
trines of radiation were denied by the latter philosopher in all his
writings. The passage of radiant heat through solid substances,
such as glass, and through fluids, such as water, had long been ad-
mitted, in the case where light accompanied heat. But in the case
of non-luminous heat, it was strenuously denied by Leslie, and others.
The experiments of De la Roche proved that such was the fact, at
least in the case of heat derived from terrestrial sources, and at the
same time luminous. But this subject has received a vast enlarge-
ment by the recent experiments of Melloni, who has shown that
substances differ surprisingly in their permeability to heat, and that
while some, such as alum, stop almost every incident ray, others,
as rock-salt, transmit almost the whole of the heat, and that from
whatever source derived,

The connexion of light with heat was too obvious and important
to be overlooked. To Sir W. Herschel the world is indebted for
the first great step in this curious inquiry. He examined the ther-
mometric qualities of the spectrum formed from the sun’s rays bya
common prism of glass ; and in 1800 announced the curious fact,
that the heating power increases, not only from the violet to the red
end of the spectrum, but even beyond the latter, indicating the exist-
ence of dark calorific rays. These experiments, though at first denied

426 Royal Society of Edinburgh :—Prof. Forbes’s Experiments

by some authors, were afterwards fully confirmed, and some ano-
malies which they presented, explained, by Robison, Englefield,
Berard, Seebeck*, and Melloni.

Heat, then, even unaccompanied by light, appears to be capable
both of reflection and refraction. But new modifications of light,
discovered of late years, require us to investigate how far the ana-
logy may be pursued. In 1802, Dr. Young announced his remark-
able discovery of the interference of the rays of light, or the power
of two luminous rays, properly disposed, to produce darkness by their
union, About the year 1808, Malus, a most eminent French phi-
losopher and mathematician, discovered the remarkable modification
which light undergoes by reflection from certain substances at cer-
tain angles. This modification may be easiest conceived by stating
the fact, that light so reflected becomes incapable of undergoing a
second reflection in certain positions of the reflecting surface, when
common light would be reflected.

The corresponding experiment in the case of heat was tried by
Berard, along with Malus, about the year 1811, and an account of
them was published in 1817, in the Mémozres d’ Arcueil. They found,
that when the solar beam was twice reflected in the manner just
stated, the heat and light refused simultaneously to be reflected in
certain positions of the second reflector. The same experiment was
repeated with incandescent bodies, with the same result ; and even,
as stated by Berard, with bodies having temperatures beneath that
of visible incandescence. These experiments were probably discon-
tinued in consequence of the death of Malus, and the details were
never published, if, indeed, they were ever carried to any great ex-
tent. The result has been, that Berard’s conclusion seems not to
have been generally adopted by the scientific world. The po-
larization of heat has remained amongst the doubtful facts in sci-
ence. It has been adopted in scarcely any systematic works,
whether British or foreign: and, of late years, direct evidence
seemed to be entirely against it. Professor Powell of Oxford, re-
peatedly and fruitlessly, attempted to obtain Berard’s result. No-
bili of Florence (whose recent loss science has to deplore) attempted
it likewise with the aid of his thermo-multiplier, an instrument ad-
mirably adapted for the measurement of small quantities of heat ;
and Melloni having failed to polarize even luminous heat by tourma-
lines, concurs in the conclusions of Powell and Nobili. The Vice-
President then observed, that it was under these circumstances that
the subject was undertaken by Professor Forbes, who, by means of
arrangements differing from any that had before been used, has suc-
ceeded in completely establishing the polarization of heat under all
the circumstances in which light is polarized, namely, by Reflection,
Transmission, and Double Refraction, and that it is for the esta-
blishment of these facts that the Keith Prize has been awarded by

the Council}.

* Seebeck’s memoir on this subject will be found in Phil. Mag., First Se-

ries, vol. lxvi. p. 330. e¢ seg.—Enrr.
+ Prof. Forbes’s paper establishing these facts will be found at large in Lond.

and Edinb. Phil. Mag., vol. vi. p. 134, e¢ seg. See also vol. vii. p. 349.—Enir.

on the Refraction and Polarization of Heat. AQT

Dr. Hope then stated that, in the ordinary case of the publication
of papers, the Society holds itself in no degree responsible for the
truth of the facts stated therein; but, in the adjudication of prizes,
the case is different; and that, with regard to them, the Council
are bound to be satisfied of the truth of the statements for which
they award their prize. Several memhers of the Council had seen
and satisfied themselves of the accuracy of Mr. Forbes’s leading ex-
periments before the Keith Prize was awarded ; and, some days ago,
he deemed it right to request Mr. Forbes to show him the more im-
portant of these experimental demonstrations. ‘This he succeeded
in doing in a way which left upon his mind not the slightest doubt
as to the truth of his results ; the variations of temperature being so
obviously displayed, as to prevent the slightest ambiguity as to the
true source from which they are derived. The instrument employed
in the research is the thermo-multiplier, of which the invention is
due to Nobili, though it has been greatly improved for experimental
purposes by Melloni. Professor Forbes has likewise increased greatly
its power of indicating the more delicate effects by employing a te-
lescopic apparatus, which enables him to measure a quantity of heat,
perhaps not exceeding one fifteen hundredth part of a degree of
Fahrenheit.

That the Society may fully understand the nature of the proofs
afforded by Mr. Forbes’s experiments, reference must be made to
the correlative facts observed in the case of light.

When light undergoes reflection from glass at an angle of 56°, its
physical character is found to be thus far altered, that it refuses to
bea second time reflected by another plate of glass placed to receive
the ray at the same angle of 56°, if the plane of incidence on the
second glass be perpendicular to the plane of incidence on the first.
The light is then wholly transmitted by the second plate. If the
plane of incidence be the same for the two plates, complete reflec-
tion takes place at the second plate. This illustrates polarization by
reflection.

If a number of glass plates be used, and light transmitted obliquely
through such a bundle of plates, it is in like manner found, that the
emergent light is wholly transmitted by a second similar bundle
placed parallel to the first, but is almost wholly reflected, and therefore
not transmitted, when the second bundle is placed so that whilst the
ray falls upon it at the same angle as upon the first, the plane of in-
cidence on the second bundle is perpendicular to the plane of inci-
dence upon the first bundle. This is polarization by transmission or
refraction.

Lastly, It was observed before the close of the 17th century by
Huyghens, that certain bodies, as Iceland spar, endowed with the
property of double refraction, alter at the same time the character
of the light in thetwo refractedrays. So that,if two sections similarly
cut from a crystal of Iceland spar be placed upon one another in
conformable positions, or the respective positions which they occu-
pied on the crystal, the two rays will proceed through the second
slice as they did through the first, and be refracted according to the

428 Royal Society of Edinburgh.

same laws. But if the second slice be placed unconformably upon
the first, or turned round a quarter of a circle, the ray, which at first
was ordinarily refracted, is now extraordinarily refracted; and the
ray, which at first was extraordinarily, is now ordinarily refracted.
Now, it has been found that some crystals, such as tourmaline, pos-
sess the property, first, of dividing these rays, and then of suppress-
ing or absorbing one of them; the result of which is, that when two
tourmalines, cut as we have supposed, are placed conformably, the
ray which was not suppressed by the first slice, still makes its way
through the second; but, when placed unconformably, the ray trans-
mitted by the first plate is wholly suppressed by the second. In the
latter case, therefore, not a ray of light can penetrate the two plates.
This is polarization produced by double refraction.

Now, all these modes of polarization have been recognised by
Mr. Forbes in the case of neat, and even in the case of heat wholly
unaccompanied by light. The Vice-President announced that he
had witnessed this in the most satisfactory manner in the case of
heat polarized by reflection and transmission, for which purposes,
instead of glass, (which permits scarcely any non-luminous heat to
penetrate it,) Mr. Forbes employs plates of mica, divided by a pecu-
liar process into extremely thin laminz.

But the analogies which he has established between light and heat
do not stop here. It has been foundin the case of light, that, when
the two reflecting plates before spoken of, or the two crystals, are
placed in wnconformable positions, so that little or no light reaches
the eye, we may, by interposing between the plates or the crystals
a thin lamina of a doubly refracting substance (such as mica) in a
certain position (relatively to its internal structure), cause a portion
of light, which before was incapable of reaching the eye, to become
capable of so doing. In other words, the polarized light, which at
first was incapable of reflection or transmission at the second plate
or crystal, now becomes capable of it; it has lost, to a certain ex-
tent, its character of polarization, or it is said to be depolarized.

Dr. Hope stated, that he had seen this to be most completely ef-
fected in the case of heat, by Mr. Forbes. A lamina of mica is in-
terposed between the bodies used to polarize heat unconformably
placed. When the lamina of mica has a certain position, no effect
is produced beyond stopping a small portion of the heat, which
would otherwise reach the thermometer; but when this interposed
lamina is turned 45° in its own plane, a portion of the heat which
before was incapable of reaching the thermometer in consequence
of its polarization, is now capable of doing so, and the influx of heat
is instantly indicated. The most striking exemplification of this re-
sult is found in the fact, which excited so much interest when com-
municated more than a year ago to the Society, that in certain cases
the mere interposition of a piece of mica (in the proper situation),
will cause an immediate indication of increased temperature, the
mica depolarizing more heat than it stops. Since depolarization takes
place only in consequence of double refraction, we have here an-
other undoubted proof of the double refraction of heat.

Cambridge Philosophical Society. 429

The Vice-President terminated his general and rapid sketch, in
which he alluded to the brilliant discoveries of Brewster, Arago, and
Fresnel, respecting the polarization of light,by observing that it would
be needless for him to point out the important bearing of these facts
on the question of the nature of heat, and its connexion with light.
He concluded in the following terms :—“It now only remains for
me to present to Professor Forbes the medal which has been award-
ed to him for these discoveries. I believe that I shall be joined cor-
dially by every member of the Society who now hears me, in the
fervent wish that it may be the will of the Almighty Ruler, that his
life may be long protracted, with vigour of mind and health of body
to pursue the career in which he has made an advancement so ho-
nourable to himself, and’reflecting lustre upon those great establish-
ments, the University and the Royal Society, with which he is con-
nected. I cannot doubt that he will persevere in this happy path
with the same ardour and success which have hitherto accompanied
his researches. Indeed, we have a gratifying proof that his zeal will
not be impaired, nor his success less brilliant, from the discovery in
the same field announced by him at the last meeting of the Society,
of the Circular Polarization of Heat*.”

CAMBRIDGE PHILOSOPHICAL SOCIETY.
(Continued from p. 80.)

Feb. 22.—A paper was read by Mr. Kelland, of Queen’s College,
* On the application of the hypothesis of finite intervals to the expla-
nation of the phenomena of dispersion.” The object of this paper was
to show, that by supposing, as M. Cauchy has done, the distance
between two consecutive particles of the medium of light to bear a
finite ratio to the length of wave, the phenomena of dispersion are
satisfactorily accounted for. Numerical calculations are entered
into for the purpose of verifying the formula in all the cases which
M. Frauenhofer has examined. The fact that a star appears to us as
a point, and not a spectrum, compels the author to the conclusion
that the medium of light is more dense in vacuo than in refract-
ing media, a conclusion in opposition to generally received opinions,
It is also a consequence of the above circumstance, as applied to
the author’s formula, that the forces which the particles exert on
each other follow the lawof the inverse square of the distance, and also
that the vibrations must be transversal. The author added, that by
the formula he had investigated, a marked difference was found in
the results when applied to M. Frauenhofer’s seven solids and three

* This discovery is announced in the Proceedings of the Society for Feb. 1,
1836, in the following terms :—“ Professor Forbes verbally communicated
to the Meeting, that he had succeeded in proving the Circular Polarization
of Heat, whether accompanied or unaccompanied by Light, when polarized
heat is made to undergo two total reflections within a rhomb of rock-salt ;
the plane of total reflection being inclined 45° to the plane of primitive po-
larization.”

Prof. Forbes also announced his discovery in our Number for March last,
at p. 248 of the present volume.—Eprr.

430 Cambridge Philosophical Society.

fluids; for the former a particular function of the forces was always
negative—tor the latter always positzve ; which remarkable circum-
stance the author thinks will lead to the most important conse-
quences in the theory of molecular actions,

The Rev. Mr. Whewell madesome remarks on the present state of
our knowledge of the tides. He stated that recent researches have
completely changed the position of this subject ; observation is now
in advance of theory, as, a little while ago, theory was in advance
of observation. It has been shown that the inequalities depending
on the moon’s hour of transit, declination, and parallax follow with
great exactness the laws resulting from the hypothesis of a spheroid
of equilibrium, slightly modified. In addition to this, it has recently
been discovered that the diurnal inequality of the tides agrees in
general circumstances with the equilibrium hypothesis, and that
there is a solar inequality also agreeing with the same hypothesis,
The observer may now, therefore, call upon the mathematician to
investigate the result of some theory agreeing more nearly with the
state of the case than those of Bernoulii and Laplace, and thus to
bring the calculation into accordance with the observed quantities.
It was remarked further, that this must be solved as a problem of
hydrodynamics, not of hydrostatics; but that it does not appear
likely that a satisfactory solution will be obtained, except we take
into account the retarding forces, as well as the attractive forces
and the condition of perfect fluidity. ‘This being almost the only
mechanical problem yet unsolved, which is requisite for the com-
pletion of the theory of universal gravitation, was put forward as a
subject well worthy the attention of mathematicians.

March 7.—Mr. Whewell gave an account of the recent discoveries
made by Prof. Forbes, and other philosophers, with respect to the pola-
rization of heat. Ele stated that Prof. Forbes had recently obtained
an additional confirmation of this discovery, by finding that heat, by
two internal reflexions in a rhomb of rock-salt, resembling Fresnel’s
rhomb, becomes circularly polarized under the same circumstances
as light. It was also mentioned that Biot and Melloni have very
recently ascertained that heat acquires circular polarization by trans-
mission along the axis of a crystal of quartz.*

The Rev. Mr. Willis then explained his views respecting the com-
position of the entablature of Grecian buildings. He observed that
this feature in the architecture of Egypt consisted of two members,
arising from the mode there adopted of roofing a building with beams
of stone, resting on the pillars, and supporting transverse slabs. The
upper member being resolved into two, the three divisions of archi-
trave, frieze, and cornice were produced; and the portion of the
mass which belongs to each of these members may be determined
by observing in what manner they are managed when the entabla-
ture is resolved into parts by cross-trabeation. It appears in this
way (and also by the principles which, Vitruvius implies in giving
his rules) that each member consists of a vertical face capped by

* See the report of proceedings of the Royal Society of Edinburgh, in
the preceding page.

Camden Institution. 431

some projecting mouldings ; the term cymatium denotes this group
of mouldings in all cases; and not, as has hitherto been supposed,
a particular form of moulding. The entablature in the simplest
cases consists of architrave, frieze, corona, each with its cymatium,
and the sima above; in more complex cases there are inserted also
the denticulus, and the modillion-bund, each of which has likewise
its cymatium,

March 21.—A memoir was read by S. Earnshaw, Esq., of St. John’s
College, ‘* On the Integration of the Equation of Continuity of Fluids
in Motion;” alsoa memoir by Professor Miller on the Measurement
of the Axes of Optical Elasticity of certain Crystals. This memoir
contained various determinations, from which it appears that the
law concerning the connexion of the crystalline and the optical
properties of crystals suggested by Professor Neumann, namely,
that the optical axes are the axes of crystalline simplicity, is false ;
but that it is true, in many of the cases hitherto examined, that
one of the optical axes coincides with the axis of a principal cry-
stalline zone.

Afterwards Mr. Webster, of Trinity College, made some obser-
vations on the periodical and occasional changes of the height of
the barometer, and on their connexion with the changes of tempera-
ture arising from the seasons and from the condensation of aqueous
vapour.

CAMDEN LITERARY AND PHILOSOPHICAL INSTITUTION.

January 26th.—A very perfect specimen of the Ornithorhynchus
paradoxus was shown to the meeting, and its peculiarities described.

Mr. Saxton exhibited a very ingenious and simple piece of ma-
chinery, by which the rolling of a ship labouring in aheavy sea was
perfectly imitated.

Mr. J. de C. Sowerby, F.L.S., in laying before the members some
cases of fossil shells from the London clay, arecent donation to the
Institution, suggested a plan for the advantageous arrangement of
fossils in reference to the strata in which they are found; and pre-
sented a specimen of an undescribed fossil Nautilus from the green
sand.

Mr. Wilson addressed the meeting on the characters of two fine
skulls of the African* Orang Outang. By reference to the skulls
of other animals he pointed out the comparative peculiarities of the
head for the accommodation of the senses of sight, smell, hearing,
and taste. The extraordinary development of the teeth and jaws
in the African* Orang, in harmony with the nature of its food,

* Mr. Wilson seems inadvertently to have transposed these local desig-
nations: the Chimpanzee ( T'roglodytes niger, Geoff.) is the African, and the
ordinary Orang Outang (Simia Satyrus, Auct.) the Asiatic animal; the spe-
cimen of the former recently living in the menagerie of the Zoological
Society, was brought from the Gambia coast. See our last volume, p. 161,
aiso p. 72; and vol. vi. p.457. Should the subject require further expla-
nation, perhaps Mr, Wilson will have the goodness to supply it.—E. W. B,

432 Intelligence and Miscellaneous Articles.

and serving also as instruments of offence and defence, gave rise to
the necessity for immense spines and ridges for the attachment of
the muscles ; impressing on the animal an aspect of ferocity. The
skull of the female was more smooth, the prominences less pro-
duced ; characteristic of the milder nature of the animal. In some
of the lower monkeys, viewed horizontally, the bulk of the face
concealed entirely the arch of the skull; as.the animals assumed a
more docile disposition the vault of the skull rose gradually, until
a forehead of considerable dimensions was perceived. The skull of
the male was narrow above, broad and expanding at the base, and
obtusely flattened behind ; evincing a destructive and ferocious dis-
position, and the absence of regard for offspring. In the female,
the arch of the skull was broad above, narrower below, and length-
ened out behind ; displaying Jess ferocity of disposition, more cir-
cumspection, and tenderness for offspring.

Compared with the Chimpanzee or Asiatic* Orang at present in
the Zoological Gardens, these skulls, although much larger in size,
were very inferior in perfection of development to that animal.

Mr. Sowerby then read a paper upon the “ Habits of the Plecotus
auritus,” the Long-eared Bat, which was followed by an interesting
discussion. The paper itself was inserted in our last Number, p. 265.

LXXV. Intelligence and Miscelldneous Articles.

Views on Screntiric anp Generat Epucation, applied to the pro-
posed System of Instruction in the South African College. By Sir
John F. W. Herschel, M.A., F.R.S., &c.

ie is with great pleasure that we observe from the local publica-
tions of the British Colony in Southern Africa, that in that distant
region, as in his own country, Sir John Herschel,—while devoting his
main attention and energy to the advancement and extension of that
branch of Astronomy of which his revered father and himself may
be considered at once the founders and to a very great extent the
finishers also,—yet directs his powerful and accomplished mind to
more general objects, and especially to the improvement of Educa-
tion, and the application to that purpose of the resources derivable
from the most recent advances which science and literature have
made. ‘The following letter addressed by Sir John to the Rev. Dr.
Adamson, relative to the proposed scheme of instruction in the South-
African College, will prove we think as interesting to our readers as
we have found it, and it will amply justify the remarks with which we
have now introduced it to their attention.

A good practical system of public education ought, in my opinion, to be
more real than formal; I mean, should convey much of positive knowledge
with as little attention to mere systems and conventional forms as is con-
sistent with avoiding solecisms. This principle, carried into detail, would
allow much less weight to the study of languages, especially of dead lan -

* See the note in the preceding page.

Sir John F. W. Herschel’s Views on Public Education. 433

guages, than is usually considered its due in our great public schools,
where, in fact, the acquisition of the latter seems to be regarded as the
one and only object of education. While on the other hand it would attach
great importance to all those branches of practical and theoretical know-
ledge whose possession goes to constitute an idea of a well-informed gen-
tleman, as, for example—a knowledge of the nature and constitution of the
world we inhabit—its animal, vegetable, and mineral productions, and
their uses and properties as subservient to human wants. Its relation to
the system of the universe, and its natural and political subdivisions; and
last and most important of all, the nature and propensities of man himself,
as developed in the history of nations and the biography of individuals ;
the constitutions of human society, including our responsibilities to indi-
viduals and to the social body of which we are members. In a word, as
extensive a knowledge as can be grasped and conveyed in an elementary
course of the actual system and laws of nature both physical and moral.

Again, in a country where free institutions prevail, and where public
opinion is of consequence, every man is to a certain extent a legislator;
and for this his education (especially when the Government of the country
lends its aid and sanction to it) ought at least so far to prepare him, as to
place him on his guard against those obvious and popular fallacies which
lie across the threshold of this as well as of every other subject with
which human reason has anything to do. Every man is called upon to
obey the laws, and therefore it cannot be deemed superfluous that some
portion of every man’s education should consist in informing him what
they are. On these grounds it would seem to me that some knowledge of
the principles of political economy—of jurisprudence—of trade and manu-
factures—is essentially involved in the notion of a sound education. A
moderate acquaintance also with certain of the useful arts, such as prac-
tical mechanics or engineering—agriculture—draftsmanship—is of obvious
utility in every station of life ;—while in a commercial country the only
remedy for that proverbial short-sightedness to their best ultimate interest.
which is the misfortune rather than the fault of every mercantile commu-:
nity upon earth, seems to be, to inculcate as a part of education, those broad
principles of free interchange and reciprocal profit, and public justice, on
which the whole edifice of permanently successful enterprise must be based.

The exercise and development of our reasoning faculties is another grand
object of education, and is usually considered, and in a certain sense justly,
as most likely to be attained by a judicious course of mathematical in-
struction—while it stands if not opposed to, at least in no natural con-
nexion with, the formal and conventional departments of knowledge (such
as grammar, and the so-called Aristotelian logic). It must be recollected,
however, that there are minds which, though not devoid of reasoning pow-
ers, yet manifest a decided inaptitude for mathematical studies, —which are
estimative not calculating, and which are more impressed by analogies, and
by apparent preponderance of general evidence in argument than by ma-
thematical demonstration, where all the argument is on one side and no
show of reason can be exhibited on the other. The mathematician listens
only to one side of a question, for this plain reason, that no strictly mathe-
matical question has more than one side capable of being maintained other-
wise than by simple assertion; while all the great questions which arise
in busy life and agitate the world, are stoutly disputed, and often with a
show of reason on both sides, which leaves the shrewdest at a loss fora
decision.

This, or something like it, has often been urged by those who contend
against what they consider an undue extension of mathematical studies in
oumUniversities. But those who have urged the objection have stopped

a3

Third Series. Vol. 8. No, 48. May 1836, 2X

434 Intelligence and Miscellaneous Articles.

short of the remedy. It is essential, however, to fill this enormous blank
in every course of education which has hitherto been acted on, by a due
provision of some course of study and instruction which shall meet the
difficulty, by showing how valid propositions are to be drawn, not from
premises which virtually contain them in their very words, as is the case
with abstract propositions in mathematics, nor from the juxtaposition of
other propositions assumed as true, as in the Aristotelian logic, but from
the broad consideration of an assemblage of facts and circumstances
brought under review. This is the scope of the Inductive Philosophy—
applicable, and which ought to be applied (though it never yet has fairly
been so) to all the complex circumstances of human life; to politics, mo-
rals, and legislation; to the guidance of individual conduct, and that of
nations. I cannot too strongly recommend this to the consideration of
those who are now to decide on the normal course of instruction to be
adopted in your College. Let them have the glory—for glory it will really
be—to have given a new impulse to public instruction, by placing the Wo-
vum Organum for the first time in the hands of young men educating for
active life, as a text book, and as a regular part of their College course. It
is strong meat, I admit, but it is manly nutriment; and though imper-
fectly comprehended, (as it must be at that age when the college course
terminates,) the glimpses caught of its meaning, under a due course of col-
lateral explanation, will fructify in after life, and like the royal food with
which the young bee is fed, will dilate the frame, and transform the whole
habit and ceconomy. Of course it should be made the highest book for the
most advanced classes.

Among branches of knowledge purely formal, langnage of course stands
foremost. Its importance is doubtless great as the key to the depositories
of knowledge, and as the most powerful instrument of human reason. Of
course it must form an essential part of every system of instruction. But
it should be studied as a means and not as anend. ‘The books chosen in
every language (after its first rudiments are acquired) ought to be vehicles
of other than mere verbal instruction, and the attention of the pupil ought
to be much more strongly directed to the matter than to the words. In-
deed, a foreign tongue can never be said to be in fair train of being mas-
tered, till the sense is seized and the words begin to pass unheeded. Much
of course will depend on the tact of the teacher in determining the point
where the strictness of literal construction may be relaxed or altogether
abandoned, and fluent translation substituted for it. And here I would
incidentally remark, how infinitely preferable a close written translation is
to any oral construing. A boy should come up ‘to construe” with his
written, or even—in the case of beginning—his printed, translation in his
hand ; he should read it aloud, and then be called upon to prove by literal
construction that such zs the true sense of the passage. Thus and thus
only can we be sure that the sense has not escaped him in the turmoil of
words and rules, which it is to be feared is too often the case in the usual
method. As for composition, or even translation from the vernacular into
a foreign tongue, till the point of fluent construing or translation at sight
is attained, I consider it as time mispent*. The usual practice at schools
of setting boys who know nothing, or next to nothing, of Latin, to write
Latin exercises, has always appeared to me a mere waste of their own and
their master’s time. One hour spent in acquiring a fluency of rendering
at sight is worth a week of such unnatural effort.

* [On this point we venture to express our dissent, We are inclined to think
that these two species of exercises, simultaneously practised, assist and test each
other,—R. T.]

Sir John F. W. Herschel’s Views on Public Education. 435

So soon as any of the pupils, in the opinion of the masters, shall have
acquired such a degree of proficiency in a foreign or dead language that it
can be done with advantage, I should be disposed to recommend, in pur-
suance of the principle above laid down, that its study as a mere language
should be abandoned, and that such proficients as a distinction and a re-
ward, should be drafted into a separate class, and commence the study of
some subject competent to their age, in that language. This would secure
one material advantage, viz. that, in pursuance of asubject, amuch greater
quantity of the half-acquired tongue can be made to pass through the
channels of the mind than in the mere conning over of stated passages as
exercises, and that a familiarity is thereby acquired with its forms and
idioms which can never be attained by the study of rules, or by any assi-
duity in construing and parsing. Historical works, as exciting the atten-
tion, following out a connected story, and requiring the perusal of many
pages at a sitting, seem particularly adapted to this purpose. Those of
Livy, Cesar, and even Tacitus, in the Latin; of Schiller in German ; and
the spirited biographies of Charles and Peter, by Voltaire, in French, may
be taken as exemplifying the proposed method.

In this colony, and more especially in Cape Town, two languages are
habitually spoken among those classes who may be expected to send their
sons to college, and a question may arise which of those should be taught
in the vernacular language of the country, and made the vehicle of in-
struction in the college. As to the latter point, convenience, of course,
must be consulted. It would cripple the institution of half its power te
carry on two distinct courses of tuition, under masters exclusively English
and exclusively Dutch, besides being otherwise mischievous. Probably no
parent would be found so culpably negligent of his child’s future comfort
and advancement, as to allow him to attain the age of admission entirely
ignorant of English. Such entire ignorance ought, I think, to operate as
a bar to admission. Considering also that this is, and will in all human
probability remain for centuries to come, a British possession ; that com-
munications with Britain are constant and increasing; British settlers ar-
riving yearly, and British habits gaining ground, I should conceive that,
ceteris paribus, so far as can be done without sacrificing what is more im-
portant, a preference should be given to the English language as the me-
dium of oral communication, and in the choice of elementary books.

But whether the acquisition of a critical knowledge of either of these
languages should be made a feature in the course of instruction, is another
question. For my own part I think not, being of opinion that youths
should occupy their time at school or in college in learning that which
they have not opportunity or means of learning elsewhere, and that pro-
vided bad grammar and vulgar expressions are corrected and reprobated
whenever they occur—in speech or in writing—no other express provision
for learning any language in ordinary use in the country is needed. In
fact, however, neither the English nor the Dutch languages can be criti-
cally studied without an acquaintance, in the latter case with the German,
in the former with both that language and the Latin. A knowledge of the
original meaning and mode of derivation of words is of far more import-
ance than that of mere idiom and grammatical nicety, and in this view,
as well as by reason of the vast intrinsic utility of the languages themselves,
I would strongly urge the propriety of making both the last-mentioned lan-
guages essential parts of the regular College course, and as such, to be taught
indiscriminately to all the pupils, superadding French as highly desirable ;
but leaving it optional with parents, and loading it with an extra payment.
I should hardly think it worth while to have a Greek class, though a
small vocabulary of Greek words (in the Greek character) consisting of
those whose derivatives have been ee directly into our terms of

2X2

436 Intelligence and Miscellaneous Articles.

art and science (without passing through the Latin) would be no doubt
useful. ;

I confess I do not see any valid reason for deferring the study of Latin
till an advanced period. All languages are easiest learnt early, nor am I
aware (when artificial difficulties, such as committing to memory the Eton
Grammar, &c. are discarded,) that the Latin is more difficult to acquire
than any modern language. The known fact of the readiness with which
children acquire languages, as well as the degree in which the knowledge
of words, both in children and in grown up persons, is often in advance of
their acquaintance with their import, may, I should hope, induce you, my
dear Sir, to reconsider your position, that the acquisition of general in-
formation is so far a necessary or advantageous preparation for that of
languages as to render it desirable to postpone the latter in point of time
till the former is attained.

Of the purely abstract departments of study, I shall say little, as I do
not see how the mathematical course actually established in the college
can well be amended, except in so far as the introduction of new branches
of physical science into the course of instruction, would naturally lead to
a greater development and detail of its applications, to those subjects
which admit them in a form not too difficult—at the expense, perhaps, of
some sacrifice of more abstruse and technical points.

In what is said I would not be understood as advocating a merely uti-
litarian course of instruction. Something must be conceded to ornament
and elegance. The influence of a tincture of elegant literature, early im-
bibed, on the tastes and habits of after life is far too important to be lost
sight of. The charms of well-chosen poetry, for instance, learnt in youth,
take so strong a hold on the imagination, and connect so many pleasing
associations with the memory of youthful studies, that it would be a very
erroneous system which would banish them as superfluous. Still the se-
lection should be cautiously made, with reference to the matter as well as
to the language. It is not easy to say on what defensible grounds the
feeble Pastoralsof Virgil, or the whining love-letters and wild extravagancies
of Ovid, are generally selected as the avenues by which the temple of the
Latin Muse is to be approached, when there is quite easy Latin for the
beginner, joined with pleasing narrative and far loftier and more poetical
diction to be found in the Aineid, or made the vehicle for the soundest
good sense, the noblest sentiments, and the most sterling wit in Horace.
But the consideration of these subjects would lead to a dissertation on clas-
sical literature. I will only observe that neither in the study of the Ger-
man nor the Latin languages would I begin with poetical works.

In advocating so considerable a range of instruction as I have done, it
may be reasonably asked—how is it to be accomplished ?

Without descending into a detail of each year’s work, or of the propor-
tion in which the several items are to be distributed among the limited
number of professors whom the funds of the Institution will support, I
would observe, that in many of the subjects proposed, a very limited and
extremely elementary course only is contemplated, and in some a true
statement of their scope and fundamental principles in the form of an oc-
casional lecture, might suffice. For example, the course of political ceco-
nomy might be confined to the reading of a single elementary volume of
moderate extent, such as, for example, the admirable ‘ Conversations,’ by
Mrs. Marcet. In Ethics, a subject of chief importance, some standard
work (such as Paley’s Moral Philosophy,) might be distributed over time
so as to pervade the whole duration of each pupil’s frequenting the insti-
tution. For the study of natural history, the proximity of the Museum
offers great advantages. An occasional visit to that collection would form
an excellent comment on whatever outline of animated nature might be

Sir John F. W. Herschel’s Views on Public Education. 437

put into the hands of the junior classes. The best mode of disposing of the
subject of jurisprudence would perhaps be by lecture, but on a very limited
scale. A few lectures also on the useful arts—engineering and manufac-
tures, might, perhaps, satisfy all the requisites of the occasion.

Drawing should, of course, be taught by a drawing-master, and paid
for as an extra; but the principles of perspective should be included in
the course of geometry. The physical sciences—those especially which
most require experimental elucidation (as all do, more or less), could
hardly be taught adequately otherwise than by a regular course of lectures.
As a single elementary compendium of physical science, I know nothing
comparable to the ‘‘ Physics” of Dr. Arnott; but without the elucidation
which experimental lectures afford, the study of this, or any other work
must be insufficient to communicate distinct and satisfactory notions. No
provision, however, (I believe,) exists for any such course, and as no one
can be expected, or indeed ought, in justice, to be suffered to perform so
extensive a task gratuitously, there is no course open but one of the fol-
lowing, or a combination of them all:

Ist, To establish one or two lecturing professorships, with salaries from
the funds of the institution ;

2ndly, To provide for their support by fees from the pupils ;

3rdly, To apply to the public for support by subscription ;

And, lastly, to apply to Government for assistance.

That any, or all of these modes, independent of the last, would prove
permanently sufficient, is much to be doubted. But no worthier or more
truly useful application of a portion of the public treasure than for the
maintenance of a high standard of education, in at least one point, the
metropolis of the colony, can be imagined—supposing such an application
made, and successful. The professor or professors, being APPOINTED and
SALARIED by Government, it would devolve upon the resident masters of
the college to enforce the attendance of their classes (for which no payment
should be required), to aid their progress by a course of reading, prospec-
tive and retrospective, and to estimate their proficiency by public and pri-
vate examination.

But in that case I would by no means confine the benefit of the lectures
within the walls of the institution. The doors of the lecture-room should
be thrown open, not only to the pupils, but to the public in general, on pay-
ment of a small fee in aid of the professor’s salary. This would have several
highlybeneficial effects: 1st, Theaugmentation of his income would be amo-
tive to the professor to render hislectures intelligible andattractive. 2nd, It
would afford an opportunity to many adult persons, tradesmen and others,
to acquire knowledge of a kind which must be useful to themselves, and
have a direct tendency to develope the internal resources of the colony.
3rdly, It would probably furnish to many an attractive counteractive of
intemperate and idle habits, which mainly grow out of the absence of some
object of interest enough to engage the attentiou. 4thly, It would afford
to parents and relations of the pupils an authorized and no way invidious
opportunity of witnessing in person the actual process of instruction to
which they are subjected. Lastly, but not of least importance, should
any unforeseen circumstance, such as want of funds, occur, to suspend for
atime, or permanently to cripple the efficiency of the institution itself,
the lecturing professors being entirely or chiefly supported from without,
and independent as (in this view of the subject) they would be of its internal
arrangements, would still continue to perform their duties, so that the public
instruction, though grievously wounded (as it must be, by any event, so
much to be deprecated) would not be entirely annihilated, and a rallying
point would always be preserved for a reconstruction of a more extended
system, whenever the necessary means should be forthcoming,

438 Intelligence and Miscellaneous Articles.

I will here recapitulate the heads of the several branches of instruction
I have above endeavoured to recommend.

Laneuacers.—Latin and German, Greek Alphabet and Vocabulary;—

French, evtra.

History.—1. Ancient Greek, Roman (Jewish ?).

2. Modern—chiefly those of England and Holland; European
and General in less detail.

Natura History.—1. General subdivisions of Organic nature.

2. Particular History of the more remarkable Animals and
Vegetables.

-GrocrapHy.—1l. Political—Ancient and Modern.

2. Physical-—-1. Form of the Earth.—2. Traces of its former
condition.—3. Natural subdivisions.—4. Climates.—5. Atmo-
sphere. Winds. Seas. Tides.

PuysitcaL Scrence.—Mechanics, including Hydrostatics, &c. Astro-

nomy. Chemistry. Optics, &c.

N.B. The climate is remarkably favourable for Optical Lectures, which
might be splendid and most attractive.

Usrrut Arts.—Engineering, including the nature of the Steam Engine.

Agriculture and Horticulture. Draftsmanship (extra).

Sociat Retations.—Ethics. Jurisprudence. Political Economy.

Maruemarics.—Arithmetic, Geometry, Analysis, Applications.

Inpuctive PHiLtosopuy.—Novum Organum of Bacon, omitting his

specimen of the application of his own principles to the Nature of
Heat.

A few brief remarks on the subject of public examinations may not be
irrelevant, and I should certainly not have hazarded them had I not been
requested by you to state my impressions as to what may prove of benefit
to the objects of the institution prospectively ; and it is in the spirit of
that request, and without the slightest wish to criticise anything which I
have observed in the only examination at which I have had the honour to
be present, that T do so.

First, then, I think it would be desirable that some portion of the ex-
amination of the senior classes should be conducted in writing, and with
deliberation, not only in mathematics but on other subjects. From what
I have been in the habit of observing in such matters, I am disposed to
think that a combination of written with oral answers, is necessary to give
an effectual trial to the merits of any proficient.

In the next place, I would suggest, that the number and variety of prizes
given may quite as easily be too great as too small, and that a certain re-
serve on this point is essential to keeping up the value of such distinctions
in general.

Lastly, I should be disposed to suppress altogether a practice which I
have observed to exist, of the successful candidates for prizes returning
thanks to their judges. There is no distinction which can possibly be
awarded to a youth at college which ought not to have the immediate
effect of humbling him in his own sight, and inducing him to retire in si-
lence and meditation on the share which his own good fortune, or the ill-
luck or diffidence of his competitors may have had in his success—on the
numbers of questions which might have been proposed to him, and which
he could not have answered, and on the immeasurable interval which still
separates him from excellence—as well as in forming inward resolves,
to let his future exertions be greater than his past. Sucha frame of mind
is incompatible with any kind of public declamation.

{ remain, dear Sir, yours, with much esteem,
J. F. W. HERSCHEL.

Intelligence and Miscellaneous Articles. 439

ON THE AURORA BOREALIS OF NOVEMBER 18TH, 1835, as
WITNESSED AT COLLUMPTON IN DEVONSHIRE. BY N.S.
HEINEKEN.

To the Editors of the Philosophical Magazine and Journal of Science.

GENTLEMEN,

In the Number of the Philosophical Magazine for this month
(February) there appears to be a mistake in the date given by Mr.
Sturgeon for the occurrence of the Aurora Borealisin November last,
and that we should read the 18th instead of the *« 16th of Nov. 1835.”
If such should be the case, allow me to state that my attention was
called, by a friend, to the same phanomenon on the evening of the
18th of November. The aurora was seen here about a quarter be-
fore nine o’clock, but I did not observe it until half-past, at which
time it presented precisely the appearance described by Mr. Stur-
geon. Waves of light appeared to roll, in rapid succession, from
the horizon to the zenith, which were succeeded by columns, some-
times of a yellowish and at other times of a lilac tint. The light of
the aurora was sufficient to produce a shadow upon a white wall,
and to enable me to ascertain the hour by my watch. Several me-
teors were seen; one of these, at nearly fifteen minutes before ten
o'clock, had almost the brilliancy and apparent magnitude of Ju-
piter. It passed from towards the north to the west. The dura-
tion of its course did not much exceed a second, and it left a train
of reddish-coloured sparks, the length of which appeared to be
equal to one half of the space passed over. Although I listened
attentively, I heard no explosion. The state of the thermometer
for the preceding day was, max. = 52°, min. = 44°. For the 18th,
max.= 514°, min. = 34°. The depression in the temperature took
place after the appearance of the aurora, for at ten o’clock that night
the thermometer stood at 42°. I am, yours, &c.

Collumpton, Devon, Feb. 3, 1836. N.S. HeInexen.

[We have annexed to the notice of a paper by Mr. Christie in
our report of the proceedings of the Royal Society, at p. 413 of the
present Number, references to other communications relative to this
aurora.—EpIr. ]

LIEUT. LECOUNT’S REPLY TO MR. BARLOW.

We have received a letter from Lieut, Lecount, informing us that
he has published a pamphlet in reply to Mr. Barlow’s letter in our
last Number, p. 291. He states the following as the points at issue be-
tween them ; and our readers will have an opportunity of judging
how far he has succeeded, by a perusal of his reply, which is advertised
on the wrapper of our present Number.

“ Mr. Barlow has called an ellipse, which vanishes with respect to
depth at one end, a fishbellied rail ; and has asserted that it deflects
4, when a parallel rail deflects 3. I have shown that it is the parallel
rail which deflects 4, while the fishbelly only deflects 3.

“« Mr. Barlow asserts 10 tons to be the longitudinal extension of
iron. I assert that his own experiments only show 9 tons.

440 Intelligence and Miscellaneous Articles.

«¢ Mr. Barlow asserts the neutral axis in rectangular bars to be
as 1 to 4. I assert that with his own formula and his own experi-
ments it is as 1 to 10.—Mr. Barlow in another mode of calcula-
ting it for railway-bars gives it as 1 to 9. I say that his own experi-
ments and his own formule show that it is as 9 to 1.

«« Mr. Barlow assigns 7 tons as the strength of certain rails. I say
his own formule will only give half that strength.

“« Mr. Barlow asserts that the deflection of a rail is the same at all
velocities of the engines. I assert that it is not.”

BOTANICAL SOCIETY OF EDINBURGH.

We rejoice to observe that a Botanical Society has been established
in Edinburgh. At a meeting which took place on the 17th of March,
the Society was constituted, under the title of ‘‘ The Botanical Society
of Edinburgh,’—the meetings to be held on the second Thursday of
every month, from November to July inclusive.

Professor Graham has been elected President, and Drs. Greville
and Balfour Vice-Presidents of the Society for the present year.

The advancement of Botanical Science is the object of the Society.
Its operations will for some time be confined principally to the hold-
ing of periodical meetings, to correspondence, to the formation of an
herbarium, and the interchange of specimens. The last is a new
feature in the constitution of such a Society, and will be conducted
by a committee, in accordance with certain rules embodied in the
laws. The desiderata of botanists in all parts of the kingdom will be
supplied, as far as possible, from the Society’s duplicates, and indi-
viduals will secure the important advantage of exchanging the bota-
nical productions of their respective districts for those of others more
remotely situated. The benefits resulting to science, as well as to
individuals, by this arrangement, will it is hoped be considerable ; es-
pecially in regard to the Geographical Distribution of Plants in the
British Islands and the formation of Local Floras. The Society, be-
sides, contemplates an extension of this plan by promoting an ex-
change of specimens with botanists in other parts of the world.

The members will be divided into the following classes :—Resi-
dent, Non-resident, Foreign, and Associate. Any person wishing to
become a non-resident member must be recommended by two indi-
viduals belonging to some scientific or literary Society, and pay a
contribution of two guineas, which, without any additional payment,
will entitle him, as long as he continues annually to send specimens
to the Society, to a participation in the duplicates. To become a
Foreign Member, it is necessary to transmit 500 specimens, including
at least 100 species, or a botanical work of which the candidate is
himself the author,—the former alternative, only, entitling him to a
share of the Society’s duplicates. To continue to participate in these
duplicates, he must afterwards contribute annually 300 specimens,
including at least 50 species.

The Flora of Edinburgh, which is particularly rich, will afford a

Prof. Rigaud’s Inguiry relative to Dr. Pemberton. 441

constant supply of valuable dupiicates, and others will be regularly
obtained from other parts of Scotland,—especially the rarer alpine
species.

Saacal Secretaries will be appointed in different parts of the king.
dom. In the mean time all communications are to be addressed (post-
age paid) to the Secretary, W. H. Campbell, Esq., Botanical Society,
21 Brown’s Square, Edinburgh. -

INQUIRY RELATIVE TO DR. PEMBERTON’S TRANSLATION AND
ILLUSTRATIONS OF NEWTON’S PRINCIPIA. BY PROFESSOR
RIGAUD.

the New Memoirs of Literature* for March, 1727, there is ad-

velbised, as speedily to be published, “ Sir Isaac Newton’s Mathe-
matical Principles of Natural- Philosophy, translated from the latest
edition, with a Comment by H. Pemberton, M.D. F.R.S.” In this
notice the author says, “ I having had a very particular opportunity
of being fully informed of his real mind from his own mouth, do in-
tend to proceed in my design with all expedition; wherein I shall
present the public with such a translation of Sir Isaac Newton’s
words as shall comprehend in the fullest manner I am able his true
sense. And besides many other occasional remarks, I shall illus-
trate at large the meaning of the difficult passages by explanatory
notes, and shall demonstrate in form those numerous corollaries and
scholiums which he, for brevity, has set down without proof.” The
work is specifically mentioned as intended “ for the use of mathe-
matical readers,” to distinguish it from the popular “ View of Sir
Isaac Newton’s Philosophy,” which Pemberton then had in the
press. This came out in 1728, with a preface containing many cu-
rious particulars respecting Newton, towards the end of which it is
said, ““ As many alterations were made in the last edition of the
Principia, so there would have been many more if there had been a
sufficient time. But whatever of this kind may be thought wanting I
shall endeavour to supply in my Comment on that book. I had rea-
son to believe he expected such a thing from me, and I intended to
have published it in his lifetime. .... This Comment I shall forth.
with put to press, joined to an English translation of his Prin
which I have had some time by me.”

Dr. Pemberton died in March, 1771, and in the same year his
Course of Chemistry was published, by his old friend Dr. James
Wilson. The editor prefixed a biographical preface, from which we
learn that Motte’s Translation of the Principia, which came out in
1729, put astop to Dr. Pemberton’s intention. Indeed, he expressed
in his advertisement the fear of being, in this manner, anticipated
in his design, and it is to be regretted that his fears were realized.
It is best, certainly, when the reader is able, for him to study the
original, and to a mathematician there is no great difficulty in ma-
thematical Latin ; but even if a complete edition in English, exe-
cuted in a manner worthy of such a work, be not considered as a
desideratum in British literature, a comment like Pemberton’s must

* Vol. v. p. 239,

cipia

442 Intelligence and Miscellaneous Articles.

in all probability have contained much that was valuable. In the
Abridgement * of the Philosophical Transactions Dr. Hutton has
given an account of Pemberton, and says that “ after his death many
valuable pieces were found among his papers.” In the enumeration
of them we find “A Comment on an English Translation of the
Principia.” This appears to describe the work in question ; but al-
though the account is almost wholly taken from Dr. Wilson’s Me-
moir, the original does not express the fact quite so strongly ; it
only says +, “ The Doctor advertized he would publish a Comment
on an English Translation of the Principia, and I find in his copy a

reat number of papers written for that purpose.” This seems to in-
dicate that the Comment had not been completely arranged ; but at
the same time it gives every reason to conclude that materials for
it had been collected. It is not impossible that the manuscripts may
yet be in existence ; and if they are, the best way of bringing them to
light appears to be by recalling the attention of the scientific world
to the circumstance.

Dr. Pemberton’s will was executed August 7, 1769, in it he be-
queaths his printed books to Dr. Wilson ; but his papers must have
been included in the residue of his property, all of which he left to
Mr. Henry Miles, whom he describes as a timber-merchant at Ro-
therhithe{. This gentleman married Dr.Pemberton’s niece, by whom
he had “two sons, both of age and in perfect health and strength §,”
[1771.] If any readers of the Philosophical Magazine should be ac-

uainted with their descendants something might probably be learned.
from them.

It is well known that Dr. Pemberton undertook the publication of
the third edition of the Principia. Newton entertained so high an
opinion of his talents ‘‘that he even solicited Dr. Mead to prevail on
him to assist him” in the work ||; and he was so well satisfied with the
care which the editor took in the execution of his task, that, with
his accustomed generosity, he nobly rewarded it. This engage-
ment, Dr. Pemberton says **, “obliged me to be very frequently with
him ; and as he lived at some distance from me, a great number of
letters passed between us on this account.” It isnot likely that these
letters should have been destroyed, and if they could be recovered
they would form an important addition to our stock of scientific
history. The correspondence with Cotes, during the publication of
the second edition of the Principia, is preserved in Trinity College,
Cambridge ++, and thus we should have the means of following New-
ton’s progress to the completion of his stupendous work.

P. R.
* Vol.vi. p. 570. + Wilson’s Preface, ape
+ In Manning and Bray's History of Surrey, vol.ji. p. 235, Henry iles,

Esq. is recorded as a subscriber in 1788 of 100/. to the charity-school at
Rotherhithe. °

§ Wilson, p. xxiv. || Zbid., p. xiii. q Ibid., p. xiv.

** Prefaee to View of Newton’s Philosophy.

++ Bishop Monk’s Life of Bentley, p. 180.

Intelligence and Miscellaneous Articles. 443

ON SUBERIC ACID AND ITS COMBINATIONS.
Examination of Cork.—M. Chevreul has given the name of suberine
to cork freed from those substances which can be extracted from it
by digestion in water, alcohol, and ether.

‘Bther digested upon cork acquires a pale yellow colour; this solu-
tion affords by evaporation a substance which is deposited in small
acicular crystals. This substance resembles a resin, and M. Boussin-
gault has called it resin of cork. Nitric acid converts it into oxalic
acid and a substance resembling wax, which M. Chevreul has deno-
minated cerine.

Resin of cork contains

Carbon ...... 0°824 = 32 eqs.
Hydrogen .... O-111 = 26 eqs.
Oxygen...... 0°065

Suberine partially dissolves in the alkalies ; and the alkaline solu-
tion affords a brown precipitate on the addition of an acid. The pre-
cipitate is converted into suberic acid by treating it with nitric acid.

That part of the suberine which does not dissolve in the alkalies,
consists of lignin and a little resin.

It appears most probable that it is the principle soluble in the al-
kalies, which in the cork gives rise to the production of suberic acid :
two facts tend to confirm this opinion, one that M. Chevreul has dis-
covered, that the epidermis of the birch produces a large quantity of
suberic acid; and the other, M. John has found that this epidermis
is almost entirely soluble in solution of potash.

The results of the analysis of suberic acid by M. Boussingault indi-
cate nearly the same composition as already given by M. Bussy, viz.
Anhydrous acid. Hydrated acid.

Carbon .... 0°612 = 16 eqs. Carbon .... 0-557 = 16 eqs.
Hydrogen .. 0:076 = 12 eqs, Hydrogen... 0°079 = 14 eqs.
Oxygen.... 0°304 = 3 eqs. Oxygen.... 0°364= 4 eqs.

Suberic ether may be prepared by heating a mixture of 4 parts of
alcohol, 1 part of muriatic acid, and 2 parts of suberic acid. It is
rather heavier than water, of a faint smell, and disagreeable taste. It
is colourless, oleaginous, and boils at 450° Fahr. Its composition is

Carbon ...... 0°627 = 24 eqs.
Hydrogen.... 0:096 = 22 egs.
Oxygen .... 0276 = 4 eqs.

But C* H® O#= CH’ O3 + C’ H' + H2O. Thus suberic
ether is subject to the general law which governs the composition
of zthers of the same kind.

By distilling suberic acid and lime at a moderate temperature,
M. Boussingault has obtained, amongst other products, a volatile oil,
which possesses the general properties of essential oils. Its odour is
powerful and aromatic. When separated from the hydrocarburets
with which it is mixed, it boils at 276°8° Fahr. ; it does not become
solid at 18° Fahr., and affords by analysis,

Carbon...... 0:766 = 14 eqs.
Hydrogen.... 0°108 = 14 eqs.
Oxygen...... 0126 = 1 eq.

444: Intelligence and Miscellaneous Articles.

The specific gravity of its vapour ascertained by the method of M. Du-
mas was found to be 4-392. The formula, C'° H'* O, compared to that
of suberic acid, C'® H'* O+, presents a remarkable relation, showing
that the essential oil obtained by the action of lime on suberic acid
differs from the acid only in containing 3 eqs. less of oxygen: ac-
cordingly when this oil is exposed to the air it becomes distinctly
acid.

When the essential oil is treated with nitric acid, violent action en-
sues, and it is converted into suberic acid. It will now be seen that
the volatile oil obtained from suberic acid presents a certain analogy
to the essential oil of almonds, which MM. Liebig and Weehler consider
as a hydruret of the radicle of benzoic acid. If we suppose the ra-
dicle of suberic acid to be C'* H?2 O, then the volatile oil, the formula
of whichis C6 H‘+ O, may be likewise represented by C'° H O+H?;
in this case it will be a hydruret of suberyle. The production ofa
body analogous to hydruret of suberyle by the mode described above
is not easily explained. It only appears in a general manner, that
under certain influences, an organic acid may be reduced at the ex-
pense of its own elements, and may be modified in such a manner
that the result of this modification shall be a less oxygenized body,
approaching in its nature to the radicle of the acid.—L’ Institut, Jan.
27, 1836.

PHLORIDZINE.

MM. de Koninck and Stas have discovered a new organic substance
in the barks of the apple, pear, and wild cherry, which they call phlo-
ridzine, from ¢Aoos, bark, and 6.Za, root ; these chemists having ob-
tained it from the cortical part of the root of these trees. When pure
it is of a dead white colour, and commonly crystallized in silky needles ;
it is very slightly soluble in water, but it increases in solubility by an
increase of temperature, dissolving to any extent in water at 212°.
Persulphate of iron colours its solution brown, and throws down a
yellow precipitate, whilst the protosulphate does not act upon it.
Phloridzine may be obtained by boiling the bark in water for 4 or 5
hours, and repeating the boiling for 2 hours. By leaving the solution
in convenient vessels for about 36 hours, the phloridzine will be de-
posited in brown crystals on the sides of the vessel. It may be ob-
tained in larger quantity and in greater purity by digesting the bark
with warm alcohol for 7 or 8 hours and distilling the alcohol; by
standing for 24 hours the phloridzine will be deposited. Its compo-
sition is stated at 14 eqs. of carbon, 9 of oxygen, and 18 of hydrogen.
—L’ Institut, Feb. 3, 1836.

THEBAIA, A NEW ALKALI IN OPIUM.

M. Couerbe discovered this new substance in the solution from
which the muriates of morphia and codeia had been separated by
Gregory's process. It was separated by its discoverer in the following
manner : the mother waters above mentioned were evaporated to the
consistence of a syrup ; this contains bimeconate of lime, morphia,
narceia, meconin, narcotina, and thebaia: muriatic acid is to be added,

Intelligence and Miscellaneous Articles. 445

to separate a black fatty matter containing ulmic acid, which is removed
by a skimmer from the surface of the liquid. To the solution thus
purified, ammonia is to be added, which occasions a black deposit of
morphia and thebaia. This precipitate is to be dried, powdered, and
treated with boiling zther, in which the’thebaia, though only slightly
soluble, dissolves. When the ether is separated by distillation, the
thebaia is deposited in small reddish crystals, which are to be purified
by boiling in alcohol with animal charcoal. It is then to be dissolved
in ether, and by spontaneous evaporation crystals are obtained.

Thebaia, thus prepared, is perfectly white, strongly alkaline, and
soluble in alcohol and ether. In the first liquid it crystallizes, like
the sugar of grapes, in small mammillated crystals, but in the second,
in brilliant flat rhombic crystals: When heated to about 266° it
fuses, and does not solidify till its temperature is reduced to 130° ;
whereas narcotina fuses at 338° and solidifies at 266°. Codeia
fuses at 302°, and meconin at 194°. By fusion, thebaia loses 4 per
cent., or two equivalents of water. Concentrated acids convert it into
a resinous substance, whereas when properly diluted, they combine
and form crystallizable salts with it. By friction it becomes nega-
tively electrical.

It is composed, according to M. Couerbe, of

Carbon ...... 71:976 = 25 equivalents
(eis COB Dasam2ew 0 ,
Hydrogen.... 6460 = 27 do. ee

Oxygen .... 15:279

M. Couerbe gives the following table of the colours produced by
agitating the peculiar substances of opium in a bottle with sulphuric
acid and air. Nitric acid oxidizes them so rapidly that the progress
of the oxidation cannot be followed. The experiment is to be made
in a four-ounce phial, with six grains of the substance, with nearly
half an ounce of sulphuric acid containing nitric acid: strong agita-
tion is to be employed. At first the colour is not very deep ; but it is
developed in a few minutes.

Thebaia is rendered instantly red, becoming deeper and deeper by
time ; when examined in thin portions the colour has a yellowish tint.

Narcotina, at first yellow, and remains so for seven or eight minutes,
then becomes red.

Codeia immediately becomes of a very pale green colour, which
passes to a vert-russe after some time.

Morphia becomes almost immediately of a green colour.

Meconin, no immediate effect, but in 24 hours the mixture becomes
of a superb rose colour,

Narceia immediately becomes nearly of a mahogany colour.

Whensulphuric acid, which contains no nitric acid, isemployed, then

Thebaia gives a rose-colour, with a shade of yellow ;

Narcotina, a blood red colour ;

Codeia, a green colour ;

Morphia, a brown colour ;

Meconin, first a turmeric yellow and then red ;

Narceia, a chocolate colour.

446 Intelligence and Miscellaneous Articles.

M. Couerbe obtained from 40 pounds (French) of opium, the fol-
lowing products :
1 ounce of meconin,
14 ounce of codeia,
$ ounce of narceia,
] ounce of thebaia,
50 ounces of morphia.
The narcotina, which remained in the marc, was not extracted.—
Ann. de Ch. et de Ph., lix.136.

NEW RENAL CALCULUS.

There has been recently found in the kidney of a young girl 20
years old, who died of a calculous disorder, several calculi which pre-
sent some remarkable particulars. The largest of these calculi
weighed about 19 grs.; it was rounded, and covered with several ex-
crescences resembling the mulberry calculus. Its composition offers
an example not yet noticed of the association of oxalate and carbo-
nate of lime, being composed, according to an analysis of M. Bour-
chardat, of about 0:4 of oxalate of lime, 0°2 of carbonate of lime, and
colouring matter, blood, and loss 0°4. A notable quantity of iron was
detected in the organic portion of the calculus.—LE’ Institut, 24 Fev.
1836.

SOLIDIFICATION OF CARBONIC ACID.

M. Thilorier has read to the Academy of Sciences a memoir con-
taining an account of the means by which he rendered carbonic acid
solid; and he also gave some details respecting liquid carbonic acid.

He finds the specific gravity of the liquid acid to be *83, water
being 1-; it dissolves in all proportions in alcohol and ether :
potassium decomposes it, but the common metals do not. A jet of
carbonic acid, directed upon a spirit thermometer, caused it fall to
194°* below zero Fahr. The cold would have been still greater if
the bulb of the thermometer could have been entirely covered by
the jet.

The solidification of carbonic acid was effected in the following
manner: a jet of liquid carbonic acid was received in a glass vial ;
the expansion which it undergoes is about 400 times its original
volume, and by this so intense a cold is produced that one part of the
carbonic acid congeals in a white powder and adheres to the glass.
This powder exists for some minutes, and without any pressure. If
the finger be placed on solid carbonic acid, the heat converts it into
gas, the expansion of which repels the finger. A few grains of this
powder, closed in a vessel, soon expelled the cork.

Solid carbonic acid contains a little water, which is doubtless derived
from the moisture of the air. In order, however, to remove all doubts,
it would be necessary to get rid of the hygrometric moisture, both of
the air and of the vessels, because it might be supposed that this

* These are lower temperatures than have ever before been artificially
produced, and lower also, we believe, than any which have yet been ob-
served in nature.—Epir,

Solidification of Carbonic Acid. 447

water facilitates the congelation of the acid, as is the case with
chlorine.

As to the temperature of this congelation, it was determined by
using a spirit thermometer graduated to 187° below zero, to which
about 44° must be added for the tube of the thermometer which could
not be cooled, so that the cold observed was not less than 231°.

These experiments were verified by commissioners, among whom
were MM. Thenard and Dulong.—Journal de Chim. Med., tome ii.

p.3.

_ ARSENOVINIC ACID.

M. Felix D’Arcet has found that when arsenic acid is made to act
upon alcohol, a new acid, analogous to the sulphovinic and phospho-
vinic‘acids, is formed.

Arsenovinate of barytes is composed of

Barium........ 27°20

Carbon........ 19°21
; Hydrogen...... 3°33
ATSEHIG 3)... 20... 15:31
Oxzyeenye ss ....d- 34:95— 100°
Arsenovinic acid is stated to be formed of
Calculated. Experiment.
cs Dees Oe ak 24°93
PAPO R, So eter Oe 4°47
PP ioe a4 38°91
O7 ........ 29°4—100° 31°69—100-

Journ. de Chim. Med., tome ii. p. 11.

METEOROLOGICAL OBSERVATIONS FOR MARCH 1836.

Chiswick.—March 1. Cloudy: stormy. 2. Fine. 3. Showery. 4. Rain:
windy at night. 5.Fine. 6. Rain. 7.Cloudy. 8.Rain. 9.Frosty:
fine. 10. Hazy: drizzly. 11. Fine. 12. Stormy and wet. 13. Fine.
14. Stormy and wet. 15.Rain: stormy. 16.Very fine. 17. Cloudy and
windy. 18,19.Hazy: fine. 20. Veryfine. 21.Slight haze. 22. Drizzly.
23, Hazy: slight rain: windy at night. 24. Fine. 25. Heavy rain: stormy
showers. 26. Cold and windy: slight showers. 27. Frosty : fine.
28. Stormy and wet. 29. Clear and cold: rain. 30. Heavy rain.
$1. Stormy showers : clear arid windy.

Boston.—March 1. Cloudy: rain early a.M.: rainp.M. 2. Fine: rain p.m,
$. Cloudy. 4.Foggy. 5.Fine: rain early a.m.:rainr.m. 6. Cloudy,
7. Fine. 8. Cloudy: rain early a.m. 9. Fine; rain early a.m. 10. Cloudy,
11, Cloudy: rain p.m. 12. Fine and stormy: raine.M. 13. Fine: rain p.m,
14, Stormy: rain early a.m. 15. Cloudy: rain early a.m.: rain A.M.
16. Fine. 17. Stormy : rain early a.m. 18, 19. Cloudy. 20. Fine.
21.Cloudy. 22.Fine: rainp.m. 23.Cloudy. 24. Fine: hail-storm p.m,
25.Rain. 26, Fine and stormy. 27.Fine. 28. Rain. 29. Stormy.
30.Cloudy: rain a.m. 91. Stormy: heavy squall with rain and snow a.M.

* See note in the preceding page.

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449

NEW LAW RELATING TO PERIODICAL
PUBLICATIONS.

The Newspaper Stamp and the Newspaper Postage compared. By Joun
CrawrFurp, F.R.S. &c. &e. Reid, London.

Mr. CRAWFURD has long since acquired distinction by his contributions to
the knowledge of those countries in which he was resident. We have now to
thank him as Journalists for calling the attention of the public to the prospects
of those connected with periodical publications at the present crisis of their af-
fairs, especially as the London newspapers have apparently been careful to con-
ceal the frightful consequences which are to be entailed upon printers and pub-
lishers.

To Mr. Crawfurd, Mr. Wakley, and the Weekly Dispatch, we are indebted for
all our knowledge of this astounding proposition, respecting which it does not
appear, so far as we can learn, that any of the Printers and Publishers of the me-
tropolis who are to incur these enormous risks have been consulted.

The definitions of papers and pamphlets liable to the provisions of the Act are
quite vague, soas to make it impossible for a Printer or Publisher to know whether
or no he is incurring the under-mentioned risks and penalties. His whole pro-
perty and personal liberty will be continually at the mercy of the officers of the
Stamp Office, or of Police Magistrates, who may exercise an arbitrary discretion
as to what publications are subject to the Act.

Abstract of some of the Clauses affecting Journals, Printers, and Publishers, in the
proposed Bill for the Consolidation of the Stamp Duties.

168.—Before a journal capable of being so construed to be a Newspaper can be printed, .
an affidavit must be made at the Stamp Office, setting forth the title of the paper, in-
tended printing-office and publishing-office, private residence and names of printers and
publishers, and of other persons in any manner concerned in publishing such Newspaper,
with the name of the proprietor, or two of the largest proprietors. Affidavits to be re-
newed and amended jn certain cases, and whenever required by the Commissioners.

169.—Penalty for printing and publishing without making the above affidavits, One
_ Hundred Pounds per day. By the same clause every vender is rendered liable to the
same penalty for selling or delivering out any such journal, although ignorant that the
affidavits may not have been made in the form required by the Act. Power is also given
_ to the Commissioners of Stamps, to stop the issue of stamps until new affidavits have
been made, whether necessary or not. In other words, the Commissioners are to be
permitted to ruin any journal they please, by insisting upon new forms of affidavits,
with which, from the absence of the proprietors or other causes, it may be impossible
suddenly to comply.

170.—The affidavits to be evidence in an action at law against the printers, proprie -
tors, or publishers, until new affidavits have been delivered that the parties have ceased
to be connected with the publication;

450 New Law relating to Periodical Publications.

171.—Service of legal process at the place of abode mentioned in the affidavit, to be
deemed a legal service. Personal service being dispensed with.

174.—Every printer, or publisher, in the United Kingdom, capable of being construed
to come within the meaning of Clause 166 and schedule, is required to send two copies
of his Paper, signed with his own hand, within three days of the date of publication, to
the Stamp Office in London, Edinburgh, or Dublin, and between the hours of 10 and 3 ia
the day. Publishers living in Cornwall or Northumberland, may petition for leave to
send copies to a distributor of stamps within twenty or fifty miles, and may be refused
at pleasure of Commissioners.—Every instance of neglect in forwarding copies within the
appointed time, is to be visited with a penalty of One Hundred Pounds. The signed co-
pies are to be evidence in a court of law for two years, against the parties.

175.—Besides the written signature and printed names of the printers and publisher,
it is also to contain a ¢rue description of the house or building in which the same is actu-
ally printed, and if that description differ in any respect from the description of the
building in which the same was intended to be printed, as stated in the affidavit, for every
such offence a penalty is inflicted of One Hundred Pounds.

176.—No printer can purchase stamps of a vendor of stamps, without first giving him
a certificate that he (the purchaser) has fulfilled all the bonds and engagements required
by the Act, and which certificate must be signed by the Commissioners.

A vendor selling stamps to persons disqualified, will be fined Fifty Pounds for every
offence, and the onus is to lie with the accused person to prove that he did not sell the stamps,
‘any law or usage to the contrary notwithstanding.’

177,—Persons concerned shall, upon a bill being filed against them, be compelled to
make discovery of their own guilt, and shall all be equally liable for the unpaid duty. ,

178.—Any person having such paper in his possession shall be liable to a penalty of
Twenty Pounds for every such paper, or to be imprisoned for a term of not less than one
month, and not exceeding six months,

179.—Every person sending such paper abroad, to be liable to a penalty of One Hun-
dred Pounds for every offence.

180.—A bill may be filed against any person, without distinction, who shall thereby
be compelled to make any discovery in his power of the printer, publisher, or proprietor.

181.—Any person more than twenty-eight days in arrear of payment of advertisement
duty shall be disqualified to receive stamped paper until the arrears are paid.

182.—Every pamphlet, or literary work containing advertisements, must be entered
within six, and in some cases within ten, days at the Stamp Office, and the advertise-
ment duty immediately paid, under a penalty of Twenty Pounds for every offence.
Every person concerned in printing or publishing the paper is to be liable to the same penal-
ties. :
183.—The printing-press and types employed in printing an unstamped paper will
be liable to be seized, without any other warrant than this Act, whoever may claim to be
the real proprietors of the property.

By clause 239 every Justice of the Peace is required (no discretion being allowed) to
grant upon the application of any Constable, Police Officer, or any Officer of Stamp Du-
ties, a warrant to enter and search any house or place suspected to contain unstamped papers
alleged to come within the meaning of Schedule A, or Persons concerned in them, or print-
ing presses which may at any time have been employed in printing them. And the Officers
are empowered to seize, not only those presses, but also all other presses and ‘printing
materials found in the same house, (no matter to whom they belong) all of which are to
be forfeited. -

‘By clause 241, Officers are permitted to break open doors and make forcible entry into
priyate houses, shops, and offices, &c. -

248.—A Justice of the Peace may convict upon the evidence of one credible witness.
The accused may appeal to the Quarter Sessions, but the cause cannot be moved by writ
of Certiorari or otherwise, into any superior court.

249.—Any common informer, entitled to a pecuniary reward, in the event of conviction is
to be admitted as a credible witness. ai)

Also a convicted person may get absolved from his penalty, and even become himself
entitled to a reward, if he procure the conyiction of any other offender.

Tee te
ral is } ma <
Peay
Cee MMM TE Shag s 9,

7, A ca Ct aes ae

Lond & Edin Fal: Mag. Vor Fi.

L7G, Forbes on the Mathematical Form

VA
iN

AVIA

Lendants opunizorm strengli’
of Marble (b) and Lorttand Stone (a)

THE
LONDON anp EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES. ]}

JUNE 1836.

LXXVI. On the Mathematical Form of the Gothic Pendent.
By James D. Forses, Esq., F.R.S.L. & E., Professor of
Natural Philosophy in the University of Edinburgh.*

[With a Plate.]

ard are few points in the history of science more cu-

rious than the display of theoretical skill afforded by the
masonic works of the darker ages. Wherever the Gothic
architects derived their knowledge, it must have been both
extensive and sound; and now that the stigma attached to
the unfortunate appellation of Gothic has in a great measure
passed away, and it is admitted that pure taste may be shown
in following other than the Grecian models, we may be per-
mitted to gather lessons from these remoter times, tending to
show that the basis, at least, of what is pleasing in architec-
ture is not of a capricious or ephemeral character, but reposes
upon the immutable substratum of natural laws.

When we select the best works which have characterized
the middle ages, including both the Norman and the pointed
styles,—but especially the latter, from its earliest introduction
into Italy during the Imperial decline down to the sixteenth
century,—we are sometimes at a loss to say whether the
sound mechanical principles employed in such structures have
been more happily displayed or artfully concealed. ‘To con-

* Read before the Royal Society of Edinburgh, Feb. 1, 1836 ; and com-
municated by the Author.
Third Series. Vol. 8. No.49. June 1836. 2¥

450 Prof. Forbes on the Mathematical

fine ourselves to the Pointed style, we have a beautiful ac-
cordance amongst the perpetually rising lines of a symmetri-
calstructure. ‘These carry the eye from the base to the sum-
mit of a building with a consciousness that such a general
disposition of parts is conformable to the particular disposi-
tion of details; we have a superposition of less solid upon
more condensed parts, retreating buttresses and tapered pin-
nacles. Then the peculiar form of the pointed arch, which,
whilst it leads the eye upwards, has that in it which convinces
us of its fitness to be loaded at the summit, and to bear in
stately equipoise those spires or towers, which had their
especial adaptation to the objects of the sacred edifices with
which they were connected. The mutual support afforded by
the parts was not only always adequate, but (in the best models)
amply enough developed to prove to the eye that it was so.
Pillars are placed where they might have been dispensed
with, but they are never placed where the eye sees at once
their inutility. Spandrels of arches are lightened, though
the voussoirs might have sustained the load; open canopies
with loaded vertices, though their lightness strikes the eye
with a pleasing astonishment, are never suffered to inspire us
with a dread of instability.

Yet it often happens that the real sources of security in
Gothic architecture have been as carefully kept out of sight,
as that amount of protection required by the eye was se-
cured*. We are perfectly capable of admiring the interior
of a groined stone roof, without concerning ourselves much
with the mode in which the lateral thrust is opposed. The
vertical weight is that which chiefly affects our senses, and
that the walls should appear, as well as be, strong enough to
sustain it. Yet every carpenter knows that the lateral thrust
of his roof must somehow or other be resisted. Much more
so when stone is used, and arches which render the employ-
ment of tie-beams impracticable. The Gothic architects from
a very early period transferred the pressure to individual
points of the vertical walls, (for instance, by the beautiful co-
noical groining of King’s College Chapel, Cambridge,) and
sustained the pressures by flying buttresses of the most ele-
gant forms, which conveyed the thrust to the lateral solid but-
tresses, surmounted by those elegant but ponderous pinnacles,
which whilst they appear to be placed but for ornament, are
in reality preventing the displacement of these stays, and thus

* I find that Mr. Willis, in his interesting and elegant work on Italian
Gothie Architecture, has expressed himself in almost the same terms that
I have here used.

orm of the Gothic Pendent. 451

conducing to the great end in view. The supports of the towers
and spires of churches are in many cases quite different from
those which the eye of the spectator is taught to consider as
the real sources of stability.

We might say truly of the Gothic architects, “ Ars est celare
artem” ; but we have at present rather to do with the cases in
which it is displayed. Though we are very far from thinking
that the principles of taste are in all cases referrible to prin-
ciples of reasoning, we believe that in a vast majority of cases
they are so, and frequently to mechanical principles by no
means obvious. The ¢act,—as distinguished from definite
knowledge,—which experience conveys, is one of the most cu-
rious of our faculties, and we are often astonished on disco-
vering upon what remote analogies or reasoning our home-
liest conclusions are founded. That there is a point beyond
which mere logic is unavailable, and where its application
would be absurd, few will] deny: but we must commence with
the clear conception of a design to be answered, and means
conspiring to the given end; nor must our superstructure be
inconsistent with that design, nor opposed to, if it does not
conspire with, those means. The more obvious conditions
of stability must be fulfilled; and any ornament interfering
with them is not only superfluous but displeasing. Every
conspicuous part must have its apparent use: no portion
must have a greater share of duty assigned to it than it ap-
pears, as well as is, able to sustain.. Some of the architects
of the middle ages delighted in constructing paradoxes in
stone. ‘They violated the rules of good taste, because they
violated the rules of common sense. Every one sees that he-
lical pillars, if they be what they appear to be, are incapable
of bearing a heavy load. Short dumpy pillars seem dispro-
portioned to the chance of their flexure; very slender ones,
unless most skilfully grouped, look as if a touch of the finger
would bend them at the middle of their length. Orders of archi-
tecture of increasing heaviness as we ascend, stone staircases
which seem hung in air, and leaning towers (if we could con-
ceive that it ever occurred to an architect to execute such a
monstrosity), would be equal violations of the canons of taste
and reason. On the other hand, the most moderately expe-
rienced eye cannot look at a well-balanced building, what-
ever may be its order of architecture, or at a well-trussed
roof, however simple its materials, without a degree of con-
scious satisfaction, of the cause of which we are for a mo-
ment ignorant. ‘Though we do not pretend that the eye can
detect by mere general experience the concordance between
parts which the more refined mechanical problems present,

242

4.52 Prof. Forbes on the Mathematical

such as the relation between the intrados and extrados of an
arch, or the form of an equilibrated dome, yet it so happens
that our consciousness of fitness and the accuracy of our
theoretical views desert us nearly at the same moment, and
that we are obliged to have recourse to that middle path
which practical sagacity, long experience, and sound mechani-
cal views point out.

Professor Robison, in one of those admirable articles on
applied science with which he enriched the Encyclopedia
Britannica, and which remarkably exhibit the characteristics
just mentioned, after an eloquent appeal on behalf of the dig-
nity of roofs, has the following pertinent remarks.

** The Gothic architecture is, perhaps, entitled to the name
of Rational Architecture, and its beauty is founded on the cha-
racteristic distinction of our species. It deserves cultivation: not
the pitiful, servile and unskilled copying of the monuments ;
this will produce incongruities and absurdities equal to any
that have crept into the Greek architecture: but let us ex-
amine with attention the nice disposition of the groins and
spandrels; let us study the tracery and knots, not as orna-
ments, but as useful members; let us observe how they have
made their walls like honeycombs, and admire their ingenuity
as we pretend to admire the instinct infused by the great
Architect into the bee*.”

Having had occasion to consider some time ago what should
be the form of a depending column of uniform material, such
that the area of section should always be proportional to the
weight sustained, I was led by an easy analysis to conclude,
that it must be the solid generated by the revolution of the
logarithmic curve round its axis. The mere imagination of
such adepending body reminded me of the beautiful pen-
dents of Gothic architecture, which, though we more fre-
quently see them on a small than a large scale, have always

««* The Greeks were enabled to execute their colossal buildings only by
using immense blocks of the hardest materials. The Norman mason could
raise a building to the skies without using a stone which a labourer could
not carry to the top on his back. Their architects studied the principles of
equilibrium; and having attained a wonderful knowledge of it, they in-
dulged themselves in exhibiting remarkable instances. We call this false
taste, and say that the appearance of insecurity is the greatest fault. But
this is owing to our habits: our thoughts may be said to run in a wooden
train, and certain simple maxims of carpentry are familiar to our imagina-
tion; and in the careful adherence to these consists the beauty and sym-
metry of the Greek architecture. Had we been as much habituated to
the equilibrium of pressure, this appareut insecurity would not haye met
our eye: we would have perceived the strength, and we should have re-

lished the ingenuity.’—Art. Roor, Encyclop. Britann., Third Edit., vol. xvi.
p, 463; 10,9.

Form of the Gothic Pendent. 453

conveyed to my mind a sense of peculiar elegance; and this
notwithstanding that they occur only in the later periods of
Gothic architecture, and are rather contemptuously passed
over by the connoisseur as merely exaggerated bosses.

I have not been able to discover either in practical or de-
scriptive works any indication of the real figure of Gothic
pendents. I am perfectly satisfied, however, that if they are
not logarithmic spindles, they ought to be so. The gradual
modification of the curve from the long finely tapered ex-
tremity to the point of greatest curvature, and then the flat
receding branch, corresponds to a multitude of Gothic details ;
and an exact sketch from the best models I have been able
to procure has led me to the same conclusion.

It is not to be supposed that the architects could have had a
curve in view which was not known until long after the termi-
nation of the real Gothic zra; I conceive that it was merely
a rude approximation to that figure’which might satisfy the
eye by exhibiting some parity between the area of the co-
hering surfaces and the mass to be sustained. When we come
to reflect upon extreme cases, this supposition of the judge-
ment exercised by the eye will not appear extravagant. A
depending cylinder seems heavy at its lower part, because the
area of section is disproportioned to the weight it has to sus-
tain, and hence the upper part will appear weak and con-
tracted; for, if the depending mass be loaded until the limits
of cohesion are passed, rupture must take place there. Any
body materially increasing inferiorly would be still more dis-
pleasing. A uniform cone with the apex downwards will,
I believe, strike every one as overloaded near its centre, and
every figure having its concavity directed towards its axis
would be still more disagreeable. The form, therefore, must
be concave outwardly, and we may easily: imagine how the
abstraction of matter from the middle of the depending cone,
and the transfer of it towards its upper and lower extremities,
might produce a curve similar to the logarithmic. This
figure, in fact, embraces the essential part of what Professor
Robison calls rational architecture,—sufficiency without re-
dundancy: the section on which strength depends increases
in proportion to the mass to be sustained.

We may observe also that since the lower extremity should
be indefinitely extended (the curve becoming asymptotic, )
the eye could not be satisfied by an abrupt termination; there
is consequently always an inferior expansion which may seem
to replace the asymptotic part of the spindle removed,-and
without which the termination might appear abrupt.

One characteristic of the Gothic architecture is unity of de-

454 Prof. Forbes on the Form of the Gothic Pendent.

sign. We accordingly find the peculiar figure of the pen-
dent carried into the minuter depending ornaments for the
sake of symmetry; though the scale is almost too small to re-
quire the curve of equal strength to satisfy the eye. It is
quite obvious too, that to reverse the case we have described,
and to make masses of the form of pendents resting on their
smaller bases to sustain weights, is equally repugnant to the
principles of good architecture and good sense.

In all cases the strength actually given to pendents enor-
mously exceeds that requisite for their cohesion. It appears
from the following simple analysis that the modulus or sub-
tangent of the logarithmic curve, must, in order exactly to
prevent rupture, be equal to twice the modulus of cohesion
of the substance in feet.

« Required the figure of a depending body which shall be
just within the limit of cohesion at every part of its length.”
Let s* represent the area of its section corresponding to any
point z in a given vertical ascending line. Since the condi-
tion infers that the increase of section shall be in a constant
ratio to the increased volume of the solid,

med seus? gia
(a being a constant) ; and integrating
xz =a.hyp.log s? +c.

If we assume the body to bea solid of revolution, and like-
wise that the variable radius 7 shall become equal to unity
when w = 0, we shall have for the corrected integral

xv = 2a.hyp. log r.

Hence the contour of the pendent will be a logarithmic curve,
whose subtangent = 2a.

Now, since it {is required that the increment of cohering
surface shall be just capable of supporting the increment of
Ss aa
Tgp? 8% equal to the mo-
dulus of cohesion of the substance employed expressed in
linear measure. Consequently the subtangent is equal to twice
the modulus of cohesion, and for a self-supported body of
uniform thickness, the measure of the one and the other would
be the same.

In the cases of white marble and Portland stone the moduli
of cohesion have been stated at 1542 and 945 feet respec-
tively. The subtangents would, therefore, be 3084 and 1890
feet. We may thence calculate the logarithm of 2 upon those
scales, or the vertical height in which the radius of the section
doubles itself. This will be found to be 2138 feet in the case

mass, we must have the quantity

Prof. Ritchie on Electricity and Magnetism. 455

of white marble, and 1310 feet in that of Portland stone *.
In a pendent x times the necessary strength 7 will be doubled
in the vth part of the above intervals.

Explanation of Plate IV.
Fig. 1. Gothic Pendent.
Fig. 2. Pendents of Uniform Strength: a, of Portland

Stone; 4, of White Marble.
Edinburgh, January 16, 1836.

LXXVII. Experimental and Physical Researches in Electri-
city and Magnetism. By the Rev. Witiiam Ritcute,
LL.D., F.R.S., Professor of Natural Philosophy in the Royal
Institution and in the University of London.t

1 AS soon as the magneto-electric spark and shock were

obtained, it must have been observed that the size of
the spark increased with the length of the coil employed, and
afterwards diminished till it at length disappeared. The
physiological effects are also exceedingly feeble with a short
coil, and continue to increase by increasing the length of the
wire long after the spark has attained its maximum bright-
ness. In experimental research, and particularly in public
lectures, it is very convenient to obtain both effects from the
same magnet and revolving lifter. This is easily and expedi-
tiously accomplished by the following arrangement, which will
be understood by simply inspecting the annexed figure.

AB is the hollow axis, C D the solid axis passing through
the former, metallic contact being prevented by a cylinder of
wood. B is the disc of
copper or platina dipping
into the mercury contained
in the cell F, and G the
star or point dipping into
the cell H. ‘Two copper
wires having their ends
formed into a close spiral
by rolling them round a
thick wire are soldered to
the hollowand solid axis at
Band C. The revolving lifter of soft iron is considerably longer

* If xo denote the logarithm of 2 upon the scale in question, and M the
modulus of the common system, we shall have

Whence these numbers are computed.
+ Communicated by the Author.

456 Prof. Ritchie’s Experimental and Physical

than those commonly employed, and made of a tube of iron
instead ofa solid mass. A continuous coil of eighty or a hun-
dred yards, or even more according to the effect intended to be

roduced, is rolled about one of the ends, whilst two or three
coils of thirty, forty, or fifty yards long are rolled about the
other end. The ends of the last are collected together and
soldered to a thick wire which fits into the cylinder formed
by the spiral, each end of the single coil being terminated by
similar pieces.

When brilliant phenomena of light are required, we fix a
star of platina foil on the solid axis, and if we wish to double the
effect we fix another similar star on the hollow axis, and con-
nect the ends of the compound coil with the two axes by means
of the spiral cylinder. If we wish to exhibit chemical or phy-
siological effects we connect the continuous coil, or employ
both coils as a continuous one.

When the short coil is employed the light is exceedingly
brilliant and the shock scarcely sensible; with the long coil
the light is feeble, but the shock unpleasantly powerful, even
without wetting the hands.

The following simple addition to the revolving lifter will
supersede the apparatus which I formerly described for de-
tonating a mixture of oxygen and hydrogen by the magneto-
electric spark*. DE is a thick copper or brass wire, about
the size of a quill, and bent into the annexed form. It is
screwed into the end of the brass axis so as to have good me-
tallic contact. EP is a wire having a loop at E through
which the wire passes, the other end resting on a small disc
of copper connected with the wire W. T is a glass tube open
at the lower end and closed at the other by a sound cork, or
a piece of wood cemented in it. ‘The wire W dips into the
interior compartment I of the cup for holding mercury. A
small spiral spring is fixed on the wire a little above P in order
to secure good contact with the disc of copper. When the lifter
is made to revolve, the end of the wire is raised from the disc
at every revolution, and a brilliant spark appears at the point
P, which will detonate a mixture of oxygen and hydrogen in-
troduced into the tube.

Though these facts, which I have endeavoured to illustrate
by an improved apparatus, are generally known, I am_ not
aware that any theory has been proposed to account for the
striking difference between the physical and the chemical or
physiological effects.

The undulatory theory of light is already established on so
firm a basis, that we may employ it in the explanation of all

* [See Lond. and Edinb. Phil. Mag., vol. iv. p. 105.—Eprv.]

:

Researches in Electricity and Magnetism. 457

phzenomena in which light is in any way evolved. It is univer-
sally admitted that nothing passes from the permanent mag-
net to the lifter when temporary magnetism is induced on the
latter. It is also admitted that nothing passes from the lifter
to its surrounding coil when voltae electricity is induced on
the latter. The polarity of the electricity essentially belong-
ing to the soft iron is rapidly changed by the change of poles
in the soft iron horseshoe lifter. ‘The electricity thus thrown
into a rapid vibratory state must derange the stable equili-
brium of the electricity belonging to the coil of copper wire.
Hence if this wire or the circuit be suddenly broken, which is
the case when one of the points leaves the mercury, the rapid
motion of the electricity at the point of separation must com-
municate a corresponding rapid vibration to the electric fluid
contained in the surrounding air, and consequently to the elec-
tric fluid contained in the humours of the eye, retina, optic
nerve, and brain, which will be followed by the sensation of
light.

The ‘appearance and indefinite continuance of the mag-
neto-electric light, without deriving supply from any foreign
source, thus affords a powerful argument in favour of the
undulatory theory of light, whilst it appears to me an unan-
swerable objection to the Newtonian doctrine. As long as
the lifter is made to revolve, light of the same degree of
brilliancy continues toemanate. We can conceive this motion
continued for ever; so that the light, according to the New-
tonian theory, lurking in a small copper wire and actually
given out, would ultimately surpass all the light which has
been given out by the sun since the creation of the world. For
an infinite number of sparks, however minute, will constitute
an infinite light; whereas the whole light given out by the
sun since the creation is only a very limited quantity. Since
gold-leaf placed in the circuit is deflagrated, and a fine platina
wire heated red hot, these effects are obviously produced by
the rapid vibration of the electricity or ether essentially be-
longing to them. The metals then are obviously heated by
their own heat, an unanswerable argument against the chemical
theory of caloric.

2. In order to account for the production of the physical and
physiological effects by wires of different lengths, we must take
into view the striking difference between good and imperfect
conductors of voltaic electricity. The metals not only con-
duct much deter than liquids, but also convey the vibratory
wave much quicker. In the case of a short conductor the
whole electricity belonging to it has polarity induced on it in
an indefinitely short period ; and also returns to its natural

Third Series. Vol. 8. No. 49. June 1836. 22

458 Prof. Ritchie on Electricity and Magnetism.

state with extreme rapidity. To produce a sensation the ex-
citing cause must continue to act for a certain length of time
depending on the delicacy of the organ. The eye being the
most delicate is affected by a series of vibrations continuing
during a very short period; and hence a comparatively short
wire formed into a coil will exhibit light when the circuit is
broken before any sensible shock is experienced.

By continuing to lengthen the coil the series of vibrations
will continue during a longer period, but they may not follow
each other with sufficient rapidity to constitute light. When
any part of the body is placed in the circuit when the metallic
contact is broken, the electricity belonging to that part of the
body is suddenly forced into a corresponding polar arrange-
ment accompanied by that peculiar sensation termed a shock.
Hence in the case of five or six feet of imperfectly conducting
substances, such as the liquids of the body, a certain length of
time must be required to allow the induction to take place.

3. If these views be correct, the electric fluid instead of
being an imponderable agent possesses one of the essential
properties of ponderable matter. When a body is put in
motion it will communicate a portion of its motion to other
matter, but not without Josimg a corresponding quantity of
its own motion. Hence, agreeably to the experiments of
Mr. Faraday, when the electricity of one wire is forced to induce
electric polarity on that belonging to another wire, the mo-
mentum of the first suffers a corresponding reduction. Again,
the motion of the electricity of a wire towards a state of po-
larity will continue after the inducing cause has been removed,
thus exhibiting in another point of view the same property of
ponderable matter, viz. the inertia of matter, or in this case its
tendency to continue in motion after the impulse which first
produced the motion has ceased.

If these views be correct we have no right to expect that
bodies at different temperatures, or differently electrified or
magnetized, will have different weights, since in each of these
states they contain exactly the same quantity of ponderable
and improperly called imponderable matter.

It is a well-known fact that we receive a more powerful -
shock when electricity is being induced on the body than
when the induced electricity is returning to its natural state.
This is what might be expected from considering the energy
and quantity of the exciting agents employed, these being
either a powerful voltaic battery, or the immense quantity of
electricity put in rapid motion in a large mass of soft iron.

If these views be correct again, it is obvious that as we hear
by means of vibrations, so we see by means of vibrations, we

New Formula for solving the Problem of Interpolation. 459

are warmed by means of vibrations, and we receive an electric
shock by the sudden vibrations excited in the elastic fluid
essentially belonging to our own bodies.

LXXVIII. On a New Formula for solving the Problem of
Interpolation in a Manner applicable to Physical Investiga-
tions. By M. Caucuy.*

[NX the application of analysis to geometry, physics, and

astronomy, the questions which present themselves for
solution are of two kinds. First, it is required to find the
general laws of the figures or the phenomena, that is, the
general form of the equations which exist among the different
variables: for instance, between the coordinates of curves and
their surfaces; between the velocities, the times, and the spaces
described by bodies in motion, &c.: secondly, to determine
the numerical values of the arbitrary constant quantities which
enter into the expression of these laws, that is, the values of
the unknown coefficients contained in the equations. Among
the variables we usually distinguish, as is well known, those
which may vary independently of one another, and are there-
fore called independent variables, from those which are de-
rived from them by the resolution of the several equations,
and which are named functions of the independent variables.
Let us consider a particular function of the latter kind, and
suppose that it is derived from the independent variables by
means of an equation or formula which contains a certain
number of coefficients. An equal number of observations or
experiments, each of which will afford a particular value
of the function answering to a particular system of values
of the independent variables, will be sufficient to enable us to
determine the numerical values of all these coefficients ; and,
these values being determined, we may easily obtain such, new
values of the function as will correspond with new systems of
values of the independent variables, and thus solve that which
is called the problem of interpolation. If, for example, the
ordinate of a curve be expressed as a function of the abscissa
by means of an equation containing three coefficients, it will
be sufficient to know three points of the curve, that is to say,
three particular values of the ordinate corresponding with
three particular values of the abscissa, in order to determine
the three coefficients. ‘When these are determined the curve
may be easily traced by points, if we calculate the coordinates
of so many points in the arcs of the curve lying between the
given points, as we wish to ascertain.

* Translated from a lithograph circulated by tke Author.
97,9

4 et

460 M. Cauchy on a New Formula for

Thus, when viewed in its whole extent, the problem of in-
terpolation consists in determining the coefficients or arbi-
trary constants contained in the expression of the general
laws of figures or phenomena, on the supposition that at least
an equal number of points is given in the former or an equal
number of observations or experiments made upon the latter.
In a great number of questions these arbitrary constants enter
only in the first degree into the equations containing them.
This is precisely what happens when a function is capable of
being developed in a converging series arranged according to
the ascending or descending powers of an independent variable,
or to the sines and cosines of the multiples of an arc. ‘Then
the question is, to determine the coefficients of such of the
terms of the series as cannot be disregarded without giving
cause to fear that a sensible error in the values of the function
may be the consequence. Among the small number of formulze
that have been proposed for this purpose the most worthy of
notice are,—that derived from the calculus of finite differences
but applicable only when the different values of the indepen-
dent variable are equi-different among themselves,—and that
of Lagrange, which, whatever these values be, can be applied
to series arranged according to the ascending powers of the
independent variable. However, the latter formula itself be-
comes more and more complicated in proportion as it is found
desirable to retain a greater number of the terms of the series
in which the function is developed; and what is still more
annoying is, that the approximate values of the different orders
corresponding with the different cases in which we should
keep, first one term of the series, then two, then three, &c.,
are obtained by calculations almost independent of one
another ; so that each new approximation, far from being ren-
dered easier, is more tedious and laborious than those which
precede. Struck with these inconveniences, and led by my
investigations respecting the dispersion of light to turn my
attention anew to the problem of interpolation, I have been
so fortunate as to find for its solution a new formula, which,
both in respect to the certainty of the results and the facility
with which they are obtained, seems to me to possess such
decided advantages over the others, that I have no doubt it
will soon be generally employed by all persons devoted to the
cultivation of the physical and the mathematical sciences.

In order to give an idea of this formula, I suppose that a
function of x represented by y is developed in a converging
series arranged according to the ascending or descending
powers of x, or according to the sines and cosines of the mul-
tiples of an arc x, or, more generally, according to other func-

solving the Problem of Interpolation. 461

tions of a which I shall represent by ¢ (a) =u x (x) = v,
v(x) = w; so that we have

(1.) y=au+bv+cw++...... where a,b,c... are
constant coefficients.

Now, the question is, 1st, how many terms of the second
member of the equation (1.) are to be employed, in order to
obtain a value of y so approximate that the difference be-
tween it and the exact value may be very small, and capable
of being compared with the errors to which the observations
are liable; 2ndly, to determine in numbers the coefficients of
the terms retained, or, in other words, to find the approxi-
mate value just mentioned. The data of the problem consist
of a sufficient number of values of y represented by

Yio Yoo veveeeees Yn3

and corresponding with an equal number (7) of values of x
Fepresented ‘by 7,,2,,...... Z,, and, consequently, with an
equal number of values of each of the functions uw, v, w, ......
These several values of the functions I shall represent by

Uy 9 Ug, seeeee U, for the function u;
V,9 Uz 5. eeeeee, UV, for the function v;
W 15 Woy seeeee Wy for the function w; &c.
Thus we shall have for the solution of the problem, the num-
ber (n) of equations of the first degree among the unknown
coefficients a, b,c ......
(y= au.+ bu 4+ew + w....
(2.) Z Yo = BUly + DDy+ CWy+ cevece

I e
L Yn = AUgt Dg + C Wat cooces

and if we put z to represent generally any one of the whole .
numbers |, 2, ...... 2, these equations will all be comprised
in the general formula

(3.) Ye = AU; + DY; + CW; A cover.

The first approximation will be made by neglecting the
coefficients b,c, &c., or, what amounts to the same thing, by
reducing the series, which the equation contains, to its first
term. ‘Then the general approximate value of y will be

(4.) Y= aw;
and to determine the coefficient (a) we shall have the system
of the equations

(5.) Yy = Ay, Yo = Ay sevens Yn = Aty.

The different values of a that can be deduced from the

462 M. Cauchy on a New Formula for

equations (5.) would, whether considered separately or in
combination with one another, be all precisely equal, if the
particular values of y which we suppose to be furnished by
observation were rigorously exact. But they are not so; for
actual observation is inevitably liable to errors confined within
certain limits, and this consideration renders it advisable so to
combine the equations among themselves that, in the most
unfavourable cases, the effect produced on the value of the
coefficient a by the errors committed in respect to the values
of ¥;5 Yos «+» Yay May be the least possible. Now the different
combinations that can be made of the equations (5.) in order
to derive from them a new equation of the first degree in re-
ference to a, will all furnish values of a comprised in the ge-
neral formula

(6.) pal Ie 9, + Ka Yo + acvccvere EnYn
Ke Uy + keg Ug + corcovece kyUly

which we obtain by adding together the equation (5.), mem-
ber by member, and multiplying them respectively by the con-
stant factors /,, k,...k,. It is still further to be observed,
that, as the value of a determined by the equation (6.) does not
vary, while we cause the factors /,, /, ... &, to vary simulta-
neously in the same ratio, it is clear that the greatest among
these factors (the sign not being taken into account) may al-
ways be considered as reduced to unity.

Finally, let it be observed that if we represent by

£19 Eq coveee Eng

the errors committed in the observations and the values of
Y\ > Yo +++ Yn Yespectively, the formula (6.) will furnish an ap-
proximate value of a, the difference between which and the
true value will be

Teves tis es oe. boc epee

(7-) ag ha

It is now necessary to choose /,, /,, .-- #, such that, in the
most unfavourable cases, the numerical value of the expression
(7.) may be the least possible.

Let us represent by

Su;

the sum of the several numerical values of w;, that is to say,
what the polynomial + w, + w+ ceseseeee + %q becomes
when we so dispose of each sign in it that each term will be
positive.

Let us represent by Se, not the sum of the numerical
values Of ¢,, &95 €3 «+ én) but what the sum Sw, becomes when

solving the Problem of Interpolation. 463

in it we substitute for each value of u; the corresponding
value of <, If we reduce to +1 or to —1 each of the co-
efficients /,, k,, ... k, by so choosing the signs that in the
denominator of the fraction (7.) all the terms may be positive,
this fraction will be reduced to
Se.
Su;’

and it will afford a numerical value, at most, equal to the ratio
Sa if we represent by the sum of the numerical values of
é or, in other words, that of S<; in the case which is least
favourable. On the other hand, by assigning to h,, k, ... Irn
unequal values the greatest of which (the signs not being taken
into account) may be unity, we shall obtain for the denominator
the fraction (7.) a quantity whose numerical value will evi-
dently be lower than Swz;, while that of the numerator may
ascend even to the limit 3: and this will actually happen if
the errors ¢;, £5 +++ & be all of no amount, except that one
which is multiplied by a factor equal (the sign being disre-
garded) to unity. Hence it follows that the greatest error to
be apprehended in respect to the value of a determined by
means of the formula (6.) will be the least possible if we put

generally eco

choosing the signs in such a manner that, in the polynomial,
Ke, ty, + ig tty + veveee + ky Up, all the terms may be positive.
Then the formula (6.) will give

Sy
(9.) lier S u; ;
(Sy; being what the sum Su; becomes when in it we substi-

tute for each value of wu; the corresponding value of y,,) and
the equation (4.) will become

(10.) a

u
Su; Sys

If, as an abbreviation, we put (11..) @ = ce » we shall

have
(12.) yre Sy.

If we supposed generally « = 1, the equation (4.) reduced
to y = 0 would indicate that the value of y is constant ; and
as we should then have

u

2£>a
Su;

l F ]
= >, the formula (12.) would give y = a Sy.

464 M. Cauchy on a New Formula for

We should then take as the approximate value of y the
arithmetical mean between the observed values; and the greatest
error to be apprehended would be less for this than for any
other approximate value. This property of arithmetical means,
together with the facility with which they are calculated, com-
pletely justifies the preference usually given to them in the
valuation of those arbitrary constants which can be determined
directly by observation.

Let Ay be now what is wanting to complete the approxi-
mate value of y furnished by the equation (12.), so that we
have

(13.), y=a8y,t+ Ay.

Let us also put

(14.) v=aSu,+ Av, w= «Su; + Aw, &e. ...
we shall derive from the formula (3.)

(15.) Sy, = aSu;+bS8v, + ¢Sw,, Xe...
then from this last multiplied by « and subtracted from the
equation (1.), we obtain

(16.) Ay=bAv+cAw + &e....

Moreover, let us represent by «;, Ay;, Av;, Aw; what the

values of a, Ay, Av, Aw, deduced from the equations (11.),
(13.), and (14.), become when for 2 we substitute x;, 7 being
one of the integers 1. 2...”. Ifthe values of Ay,, A yo --AYis
are very small, and capable of being compared with the inevi-
table errors of the observations, it will be useless to proceed
to a second approximation, and we may rest satisfied with the
approximate value of y afforded by the equation (12.). If the
contrary takes place, it will be sufficient, in order to obtain a
new approximation, if we do with the formula (16.) as in the
first approximation we have done with the formula (1.). This
being supposed, let us represent by
S! A U;
the sum of the numerical values of Av;, and by
SAy;, S Aw; ..... Ke.

the polynomials into which the sum S’ A a, is changed, when
for each value of Av; we substitute the corresponding value
of Ay; or of Aw; ...... «

In fine, let

Av

ha a S'A 9;

If we can without a sensible error disregard in the series
the coefficient (c) of the third term and those of the following
terms, we must take as the approximate value of Ay,

solving the Problem of Interpolation. 465

(18.) NY, == BiG.

Let A®y be the remainder of the second order which is re-
quired to complete this approximate value, and let us there~
fore put

(19.) Ay = BS'Ay, + Ary.

Let us in like manner put

(20.) Aw = BS' Aw; + A’w, &e. ...

We shall derive successively from the formula (16.)

(21.) Ay; = bAv,+ chw; + &e. ...

(22.) SAy; = bS9’Av,;+ cS Aw,, &e. ».
and from this last, multiplied by 6 and deducted from the
equation (19.), we obtain

(23.) Aty =cA?w +, &C. oe

Let 6;, A®y;, A°w;...... be what the values of 6, A?y, A? w.
derived from the equations (17.), (19.), and (20.), become when
for x we substitute z;, i being one of the integers 1.2... 2.
If the values of A? y,, A? y, ... A?y, be very small, and capa
ble of being compared with the errors incident to the obser-
vations, it will be useless to proceed to a new approximation,
and we may be contented with the approximate value of Ay
furnished by the equation (18.). If it happen otherwise we
shall obtain a third approximation by operating upon the
formula (23.) as we have done in the first approximation on
the formula (1.). By continuing this process we shall obtain
the following rule.

The unknown quantity y, a function of the variable quan-
tity x, being supposed capable of being developed in a con-
verging series

aw+buv+cewt.

in which w, v, w represent given Fanelians ea the same variable,
if we know x particular values of y corresponding with par-
ticular values (7,, v5, v3,.-. ,) of x: if moreover we represent
by 7 any one of the whole numbers 1,2, 3.00,” and by ¥;; 2%,
V;-+» what y, u, v, ... become when for z we substitute x;; then,
in order to obesin a sufficient approximation to the general
value of y, we shall first determine the coefficient « by. means
of the formula

(II.) u=aSu;,

(in which S uw, represents the sum of the numerical values of
u,;,) and the difference of the first order Ay by means of the
formula

(IIT.) y=aSyt+ Ay.

If the particular values of A y represented by 4 my » AYy oe
Third Series. Vol. 8. No. 49. June 1836.

466 M. Cauchy on a New Formula for

Ay, can be compared with the errors of observation, we may
disregard A y and reduce the approximate value of y to

aSy;.

In the contrary case we shall determine 6 by means of the
formule

(IV.) v=aSv,+ Av Av=BS'Azy,,

(S'A v; being the sum of the numerical values of A v;,) and the
difference of the second order (A* y) by means of the formula

(V.) Ay=BS'Ay + A*y.

If the particular values of A?y represented by A*®y,, A? Yo»

. A*y, may be set off against the errors of observation, we
shall be able to neglect A*y, and therefore to reduce the ap-
proximate value of y toa Sy; + CS’ A y;; but if they can-
not, we shall determine y by means of the formule

(VI.) w=aSv;,+ Aw, Aw= BS Aw, + A®w, A?w
= y S! A’ w;.
(S" A?w,; being the sum of the numerical values of A? w;,)

and the difference of the third order (A® y) by means of the
formula

(VII.) A?y = yS" A®y; + A®y, &c.

Thus, in short, by supposing the coefficients «, 6, y ... de-
termined by the system of the equations (II.), (IV.), (VI. \ &e.
we shall calculate the several orders of differences represented
by Ay, A? y, A°y...... or, rather, their particular values cor-
responding with the values (7, 7, 73...) of the variable z,
until we arrive at a difference the particular values of which
may be set off against the unavoidable errors of observation.
Then it will be sufficient to represent as zero the value of this
difference deduced from the system of the equations (III.),
(V.), (VII.)... in order to obtain a sufficient approximation to
the general value of y.

This general value will be then

y=aS8y;,, or y= aSy,+ BS Ay;... &e.
according as we shall be able, without a sensible error, to re-
duce the series (I.) to its first term or its first two terms, &c.
Now, if we call the number of terms retained m, the problem
of interpolation will be resolved by the formula

(VIIL) y= aSy,+ BS’ Ay; + yS" A’y; + &e.,
the second member being continued to the term which con-
tains A"—1y;.

It is necessary to observe, that from the formule (II.), (III.),
(1V.), (V.), (VI.) (VIL.) ... we derive not only

solving the Problem of Interpolation. 467

(1X.) Sa; => 15 SB; = UV; S' B; => hs Sy: = Vs Sy: =U;
S’ %= its SEC),
but also

(X.) SAv,= 0; SAw,; =v; § A? w;= 0; S'A* vw; = v, &c.,
and

(XL) SAy,=0; SA’*y; = 0; S A?y; = 0; S'Aty;= 0..,

These latter formule are so many equations of condition
which must be satisfied by the particular values of a, 6, y...
as well as by those of the several orders of differences of
W, V, W... y; and hence it follows that in the calculation of these
particular values we cannot commit an error of a single figure
without being apprised of it by the bare fact of the equa-
tion of condition ceasing to be verified.

The advantages of the new formule of interpolation are the
following:

Ist. They are applied to the development by series, what-
ever be the law according to which the different terms are
deduced from one another, and whatever be the values, equi-
different or not, of the independent variable.

2nd. The new formule are of very easy application, espe-
cially when logarithms are employed in the calculation of the
ratios @, 8, y ... and in that of the product of those ratios by
the sums of the several values of the functions or their differ-
ences. Then, in fact, all the operations are reduced to addi-
tions and subtractions.

3rd. By means of these formulz the successive approxima-
tions are made with a constantly increasing facility, as the se-
veral orders of differences continually decrease.

4th. They allow us to introduce at once into the calcula-
tion the numbers furnished by all the given observations, and
thus to add to the exactness of the results by making a great
number of experiments subservient to this object.

5th. They possess this advantage also, that, on every new
approximation, the values which they furnish for the coeffi-
cients a, b, ¢ are precisely those in which the greatest error to
be apprehended is the least possible.

6th. Our formule: indicate of themselves the moment when
the calculation ought to cease by then giving differences com-
parable with the errors of observation.

7th. The quantities which they determine satisfy equations
of condition which do not allow the least fault of calculation
to be committed without being almost instantly perceived.

In the new mathematical exercises there will be found nu-
merous applications of the formule of interpolation. I shall
here quote but one of them.

Let / be the length of a luminous undulation relative to one

$AQ

468 Sir David Brewster on the Colours of Natural Bodies.

of the rays of the solar spectrum, and § the index of refrac-
tion of this ray passing from the air-into another medium: it
follows from the principles established in my memoir on the
dispersion of light, that we may develop in a converging series

(+) é according to the ascending powers of (+) ‘ and con-

0.” ;
sequently ae, and §° according to the ascending powers

erp) - Moreover, a very able observer, Fraunhofer, has de-

termined, in respect to different substances, the indices of
refraction of the rays for which the values of 7 in hundred-
millionth parts of an inch, are

2541, 2425, 2175, 1943, 1789, 1585, 1451,

and finds as the corresponding values of § relative to a cer-
tain species of flint-glass, 1°626469; 1°628469; 1:633667;
1°640495; 1°646756; 1°658848; 1°669686: in which case
the formula (VIII.) being then reduced to

2 4
6? = 2°6112351 —0:0256298 (4) +0:1081567 (4
Ye

0:0649226 etal +0°019115 ear oe:
ai ; (+-) —0-002189 (—*) ;
reproduces exactly, and without the slightest alteration, the
preceding values of 6.

September 1835.

LXXIX. On the Colours of Natural Bodies. By Sir Davip
Brewster, K.H. LL.D. F.R.S. Lond. V.P.R.S. Edin.*

HERE are few of the applications of optical science so
universally interesting as that which has for its object the
explanation of the colours of natural bodies. Sir Isaac New-
ton was the first person who ventured to refer to one general
principle all the variety of colours which are found in nature ;
and he maintained his opinions on this subject with a con-
fidence in their accuracy which seems to have confounded his
adversaries: For while his analysis of light, the most perfect
of all his labours, exposed him to the most harassing contro-
versies, his theory of natural colours, the least perfect of his
speculations, was allowed to pass without examination or
censure. |
During the century which has elapsed since the death of

* From the Transactions of the Royal Society of Edinburgh, an unim-
portant paragraph being omitted.

Sir David Brewster on the Colours of Natural Bodies. 469

Newton this theory has been generally received and admired:
In our own day it has been ingeniously defended, and beauti-
fully illustrated, by M. Biot; and, with few exceptions, it has
been adopted by most of the distinguished philosophers of the
present age.

The author of this theory has presented it under the two
following propositions, one of which states the general cause
of the phznomena, and the other the particular constitution
of natural bodies on which their colours depend.

1. “ Kvery body reflects the rays of its own colour more
copiously than the rest, and from their excess or predomi-
nance in the reflected light, has its colour.

2. “ The transparent parts of bodies, according to their se-
veral sizes, reflect rays of one colour, and transmit those of
another, on the same ground, that thin plates or bubbles do
reflect or transmit those rays.”

In estimating the truth of the theory which is contained in
these two propositions, I do not intend to enter into any ex-
amination of the postulates, facts, and reasonings, on which
it is founded. The object of the following paper is to analyse
one leading phenomenon of colour, and to apply this analysis
as an experimentum crucis, in determining the true origin of
all colours similarly produced.

The colour which I have chosen for this purpose is the
green colour of the vegetable world, and I have made this se-
lection for the following reasons :—

1. The green colour of plants is the one most prevalent in
nature.

2. It is the colour of which Sir Isaac Newton has most di-
stinctly described the nature and composition.

3. Its true composition is almost identically the same in all
the variety of plants in which it appears.

Sir Isaac Newton has described this colour in the following
manner :—

“There may be good greens of the fourth order, but the
purest are of the third. And of this order the green of all
vegetables seems to be, partly by reason of the intenseness of
their colours, and partly because, when they wither, some of
them turn to a greenish-yellow, and others to a more perfect
yellow or orange, or perhaps to red, passing first through all
the aforesaid intermediate colours. Which changes seem to
be effected by the exhaling of the moisture which may leave
the tinging corpuscles more dense, and something augmented
by the accretion of the oily and earthy part of that moisture.
Now the green, without doubt, is of the same order with those
colours into which it changeth, because the changes are gra-

470 Sir David Brewster on the Colours of Natural Bodies.

dual, and those colours, though usually not very full, yet are
often too full and lively to be of the fourth order.”

Having thus determined that the green colour of vegetables
must, according to this theory, be a green of the third order,
we must inquire into its composition. Sir Isaac has himself
stated, that the green of the third order “ is principally con-
stituted of original green, but not without a mixture of some
blue and yellow.” In point of fact, it consists of all the rays
of the green space, with the least refrangible rays of the blue
space, and the most refrangible rays of the yellow space, and
it does not contain a single ray of zndigo or violet, nor a single
ray of orange or red light. ‘This is its real composition,
whether we deduce it from the theory of periodical colours,
or obtain it by direct analysis with the prism.

In order to discover the true composition of the green co-
lour of plants, we may analyse the light which they reflect or
transmit, but the best method is to extract the green colour-
ing matter by means of alcohol, and to examine the action of
the tingeing corpuscles when suspended in that fluid. For
this purpose I have used the leaves of the common laurel,
Prunus Lauro-cerasus, as a type of this class of colours. The
leaves are torn into small shreds and put into absolute alcohol,
and the fine green fluid which is thus obtained is either placed
in a hollow prism with a large refracting angle, so as to ex-
hibit its composition in its own spectrum, or the light trans-
mitted through the fluid may be analysed by a fine prism, or
the spectrum produced by such a prism may be viewed through
a portion of the fluid bounded by parallel surfaces. By which-
soever of these methods the experiment is made, we shall ob-
serve a spectrum of the most beautiful kind. In place of see-
ing the green space with a portion of dlwe on one side and
yellow on the other, as the Newtonian theory would lead us
to expect, we perceive a spectrum divided into several coloured
bands of unequal breadths, and having their colours greatly
changed by absorption.

At a certain thickness of the green fluid there are three red
bands. By increasing the thickness, the violet and blue spaces
are absorbed, and the two inner red bands. An absorption
then begins near the middle of the green space, and after de-
stroying the more refrangible portion of that space, three
bands are left; viz. one faint band of the extreme red, one
band almost white, corresponding with the mest luminous
spectrum, and one green band contiguous to the white one.

In applying. this mode of examination to. the green co-
lours of others plants, I have found them to have invariably
the same composition. In the following list of plants of va-

Sir David Brewster on the Colours of Natural Bodies. 471

rious characters, I have given those in which I have made the
experiments with most care. [Excepting where it is otherwise
mentioned, the green fluid was extracted from the leaves:

White Lilac. Celastrus scandens.

— Convolvulus. Viburnum Tinus.
Tulip-Tree. Prunus Lusitanica.
Mignionette. Aucuba Japonica.
Common Pea. Juniperus communis.
Daphne Cneorum. Camellia Japonica.
Virginian Raspberry. _—_ The green berries of the
White Jasmine. Convallaria multiflora.
Thuja occidentalis. The green berries of the
Arbutus Unedo. Asparagus officinalis.
Hemerocallis flava.

When the green fluid obtained from these plants has stood

for three or four days, it loses its high green colour, and be-
comes of an olive-green, which grows more and more of a
brownish-yellow, till it becomes almost colourless. During
these various changes, the specific action of the fluid upon the
spectrum changes also; but neither the change of colour nor
the change of action has any relation whatever to the effects
of an increase or decrease of thickness in the tingeing corpus-
cles, by which Sir Isaac Newton explains the changes which
take place in the colour of leaves. When the fluid has be-
come almost colourless like water, it still exercises a powerful
action upon the middle of the ved space, and a faint, but still
perceptible action, at two points of the green band. This
curious fact may lead us to expect that transparent media may
yet be discovered, which shall absorb different parts of the
spectrum, while they themselves are perfectly colourless.
This effect of course cannot take place unless the rays ab-
sorbed compose white light.

In the course of these experiments, I observed a very re-
markable phenomenon, which at first sight appeared to be
somewhat favourable to the Newtonian theory. In making a
strong beam of the sun’s light pass through the green fluid,
I was surprised to observe that its colour was a brilliant red,
complementary to the green. By making the ray pass through
greater thicknesses in succession, it became first orange and
then yellow and yellowish-green, and it would undoubtedly have
become blue, if it had been transmitted through a greater
thickness of fluid. ‘This mode of producing a spectrum by
reflexion from the particles of a fluid, exhibits the phano-
menon of opalescence in a very interesting form. Had the
green fluid shown the same colour at all thicknesses, or had

472 Sir David Brewster on the Colours of Natural Bodies.

it absorbed only the red rays, the opalescent beam would have
been red throughout the whole of its path: but as the different
colours are absorbed in different proportions, and, in the pre-
sent case, in the order of their refrangibility, excepting the
blue and violet, the colour of the intromitted beam must vary
from red to greenish-yellow, as these colours are successively
taken out of it.

The analysis of this experiment is very interesting, but as
this is not the place to pursue it, I shall only remark, that I
have observed the same phenomenon in various other fluids
of different colours, that it occurs almost always in vegetable
solutions, and almost never in chemical ones, or in coloured
glasses; and that it is a phenomenon of opalescence or im-
perfect transparency. One of the finest examples of it which
I have met with may be seen by transmitting a strong pencil
of solar light through certain cubes of bluish fluor-spar. The
brilliant blue colour of the intromitted pencil is singularly
beautiful.

According to the Newtonian theory of colours, the green
of plants is of the same order as the yellow and orange into
which it is changed when it withers, in consequence of an in-
creased density, or an enlargement of size in the tingeing cor-
puscles. In order to put this opinion to the test of experi-
ment, I extracted the yellow juice from the brilliant yellow
leaves of the common laurel. This fluid becomes of a deep
red at great thicknesses. It attacks the spectrum powerfully
towards the extremity of the green space, a place where it is
not touched by the green fluid. It then absorbs the yellow
and violet, leaving a bright green, and converting the blue into
violet. At greater thicknesses, the violet disappears, and the
absorption advances gradually to the red.

For the purpose of varying the experiment, I extracted the
juice of the leaves of the privet, which become of a deep
black violet when they wither, a colour which has not the
most remote resemblance to any periodical tint. The fluid
was a deep red colour, much deeper than that of the darkest
port wine. It attacked the red part of the spectrum near the
line B of Fraunhofer, at the same place that the green juice
attacked it, leaving (wo red bands, the innermost of which
vanished at an increased thickness. It then absorbed the
violet and blue spaces generally; and having obliterated the
middle of the green space, the absorption advanced to the
orange rays at D.

Now, in both these experiments, the action of the colouring
matter of the decayed leaves is decidedly different from that
of the green juice, and there is no appearance whatever of the

Sir David Brewster on the Colours of Natural Bodies. 473

tints having any such relation as that which subsists between
adjacent colours of the same order.

From facts like these, which it is impossible to misinter-
pret, we are entitled to conclude, that the green colour of
plants, whether we examine it in its original verdure, or in its
decaying tints, has no relation to the colours of thin plates.

I have submitted to the same mode of examination nearly
one hundred and fifty coloured media, consisting of fluids ex-
tracted from the petals, the leaves, the seeds, and the rind of
plants,—the different substances used in dyeing,—coloured
glasses and minerals,—-coloured artificial salts,—and different
coloured gases; and in all these cases I have obtained results
which lead to the same conclusion. I have analysed, too, the
blue colour of the sky, to which the Newtonian theory has
been thought peculiarly applicable; but instead of finding it
a blue of the first order, in which the extreme red and the ex-
treme violet rays are deficient, while the rest of the spectrum
was untouched, I found that it was defective in rays, adjacent
to some of the fixed lines of Fraunhofer, and that the absorp-
tive action of our atmosphere widened, as it were, these lines.
Hence it is obvious, that there are elements in our atmosphere
which exercise a specific action upon rays of definite refrangi-
bility, and that this, in some of these rays, is identical with
that which is exercised over them by the atmosphere of the
sun. I have obtained analogous results in analysing the yellow,
orange, red, and purple light, which is reflected from the clouds
at sunset; but it is impossible to convey any correct idea of
the composition of these colours, without a reference to the
fixed lines of the spectrum, of which we at present possess no
distinct nomenclature.

I may mention, however, this general fact, that in the va-
rious specific actions exercised upon light by solids, fluids,
vapours, and gases, the points at which the spectrum is at-
tacked are generally coincident with the deficient lines of
Fraunhofer; and particularly with those which are common
to the light of the sun, and that of some of the fixed stars.
Hence it appears, that these rays or lines are weak parts of
the spectrum, or the parts of white light which have the
greatest affinity for those elements of matter, which, while they
enter into the composition of sublunary bodies, exist also in
the atmospheres of the central luminaries of other systems.

From the preceding experiments, it is impossible to resist
the conclusion, that the second and leading proposition of
Newton’s theory of colours is incompatible with the actual
phznomena; and we may demonstrate the incorrectness of

the first proposition by simply stating the fact, that there are
Third Series. Vol. 8. No. 49. June 1836. 3B

474 The Rev. J. H. Pratt on a Proposition

red, yellow, green, and blue media, which are absolutely inca-
pable of reflecting or transmitting certain definite rays of the
same colour with themselves.

The true cause of the colours of natural bodies may be
thus stated: When light enters any body, and is either re-
flected or transmitted to the eye, a certain portion of it, of
various refrangibilities, is lost within the body; and the co-
lour of the body, which evidently arises from the loss of part
of the intromitted light, is that which is composed of all the
rays which are not lost; or, what is the same thing, the co-
lour of the body is that which, when combined with that of
all the rays which are lost, compose the original light.
Whether the lost rays are reflected, or detained by a specific
affinity for the material atoms of the body, has not been ri-
gorously demonstrated. In some cases of opalescence, they
are either partly or wholly reflected ; but it seems almost cer-
tain, that in all transparent bodies, and in that great variety
of substances in which no reflected tints can be seen, the rays
are detained by absorption*.

LXXX. On the Proposition that a Function of § and \ can
be developed in ONLY ONE Series of Laplace’s Coefficients ;
the Function being supposed not to become infinite between
the limits 0 and x of and o and 2% of |. By the Rev.
J.H. Pratt, B.A.t

pegs important proposition is, in fact, not proved, but

assumed, by Laplace in the Mécanique Céleste, II. ii.

§ 12. Professor Airy pointed out this defect, and gave a

proof of the proposition in the Cambridge Philosophical ‘Trans-

actions: but this labours under the restriction of supposing
the number of terms in the series finite. M. Poisson has con-

sidered this among numerous other important questions in a

paper in the Connoisance des Tems for 1829, and also in his

Théorie Mathématique de la Chaleur, chap. viii. But I con-

fess it appears to me that the proposition is not proved even

in these places; though by a slight addition to the reasoning
the objection to the proof may be removed.
M. Poisson shows that if p = cosé cos @! + sin @ sin 6! cos

(¥—w’), and also if (1—2e p + a®)-? = 14a P,+a°?P,+4+....

+ 6 Pi vesweh then

1 2 .

SANG et 3 ip. ‘
L(Y) = af 48a Pitot (28+ IP. + oo}
SF (4, V') sin déldy’. 79)
* The views on this subject of Sir John Herschel will be found in a paper

by that philosopher in Lond. and Edinb, Phil. Mag., vol. iii. p. 401.—Ep1r.
+ Communicated by the Author.

in the Mécanique Céleste. AT5

S pre F f
He then says, that since ["/" . Pf (6, V’) sin 6! do! dy’
is of the form of Laplace’s coefficients, we may put it
an

pe Pee ia
and hence f (4, ¥) = Yo + Y, + «oes je Vatrtee canes
In the same manner we shall have
FOV) = Vo + OV + ence + Y',4,
the accents denoting that 4! and { are put for @ and y.

i+] pt pee
Hence Y;= —— JA ny . Pf (HV) sind dé’ dy by

the above assumption,

L284 1 fepte SIEM OY
= Sf, . P,Y’; sin@'di'dy' by the

nature of Laplace’s Coefficients. All so far is clear enough.

But in order to show that (4, ~) cannot be developed in
another series V,>+V,+ --. V; + --- he says, that if this were
possible we should have

eh aN x fin “Vien Ald al ;
Va ff _P, V/ sind déldy

by what has preceded ; and then easily deduces the result de-
sired. But surely this is no less than begging the question,
All we learn from it is that if we proceed to develop, as above,
we shall arrive at a series of determinate terms; but it does
not follow that another method of development cannot be
discovered which would lead to another series. The following
demonstration appears to be free from objection.

In the formula (1.) we may evidently interchange # and #6,
) and ¥ since P, P,... P; ... are the same functions of 4, p
and #,/. Hence from that formula we learn that the defi-
nite integral of the product of any given function of 6 and ¥,
and the function (1+3aP,+.... + (27+1)¢’P; + ....) siné
does not vanish between the limits specified above.

Now, suppose,f (4, ¥) can be expanded in the two distinct
series Q) + Q, + eee + Qy eveee and Ro+R,+...... R; 4--.e:
Then by hypothesis Q;—R, does not vanish; and conse-
quently,

st eae (1432P, bet dopaaarceds Sater) ial Py sh tesaee) sin 6
(

Q,—R,) dédy does not vanish.
3B2

47 Prof. Faraday on a supposed new

6
® P2% .
a ey - P; sin@ (Q;—R,) dd does not vanish, since

all the other terms do vanish by the nature of Laplace’s Co-
efficients.

Again, (Qo— Ro) + (Q)—Ri)+ «-- +(Q:—R,) +. =O.
Multiply by P; sin 4 and integrate ; then we have

Mees (Q; — R,) P; sinddidy = 0:

but we showed that this does not vanish if Q; and R, are

different functions. Hence that hypothesis is not true, and

therefore Q; = R, and the expansions of f (6, )) are identical.
Caius College, Cambridge, Feb. 18, 1836.

LXXXI. Ona supposed new Sulphate and Oxide of Antimony.
By Micwaer Farapay, D.C.L., F.R.S., §c. §c.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

| my Experimental Researches, paragraphs 693. 694. 695.
696.*, have, in relation to antimony, described what I con-
sidered to be a new sulphuret, and expressed my belief that a
new and true protoxide existed consisting of single proportions,
“but could not stop to ascertain this matter strictly by ana-
lysis.” Professor Rose when in London informed me that Ber-
zelius objected to my new sulphuret, and I was induced to make
more accurate experiments on that point, which showed me
my error, and accorded generally with what Rose had described
to me. I intended to publish these results in the first electric
paper which I might have to put forth; but my friend Mr.
Solly has put into my hands a translation of Berzelius’s paper,
and it is so clear and accurate as to the facts that 1 now pre-
fer asking you to publish it, adding merely that my experi-
ments quite agree with those described in it, as regards the
sulphuret. With respect to the supposed chloride and oxide,
I have not anywhere implied that I had made quantitative ex-
periments on them.

On Faraday’s supposed Sulphuret of Antimony and Oxide of
Antimony : by J. J. BErzELivs.—From his “Jahresbericht,”
No. 15.

‘«‘ Faraday has stated, that when sulphuret of antimony is
beated with more metallic antimony, a new sulphuret of anti-
mony is formed, which when in the fused state is distinguish-

* See Lond. and Edinb. Phil. Mag., vol. v. p. 170.—Enprr.

Sulphate and Oxide of Antimony. ATT

able from the common sulphuret. According to a few expe-
riments, this sulphuret of antimony is composed of Sb S, or
one atom of each element. When this sulphuret is dissolved
in muriatic acid, sulphuretted hydrogen is evolved, and al-
though a little antimony is separated, yet there remains in
solution a combination with chlorine Sb Cl, which when de-
composed with carbonate of soda furnishes a new oxide. The
mixing of this with the common oxide is said to have given
rise to the contradictory views of its composition, and also to
the appearance that the fused oxide of antimony is decom-
posed to a certain extent by the electric current only until
the new oxide is reduced.

“‘ Faraday appears convinced of the truth of this statement,
but adds that he has not confirmed by analysis the composi-
tion of this oxide, because he should thereby have interrupted
the course of his main experiments.

“This appeared to me to deserve a nearer investigation, as
well for itself as for the importance of its influence on Fara-
day’s electro-chemical views. I have therefore repeated the
above-described experiments of Faraday on the three new
combinations of antimony with sulphur, chlorine, and oxygen,
and I have found that even if they do exist they cannot pos-
sibly be formed by the means which he has described, and
they are therefore still to be discovered.

‘The following is the substance of my examination. |
mixed together very carefully and intimately sulphuret of an-
timony and metallic antimony in the proportions that, through
melting, the combination Sb+S must be formed: the mixture
was then put into a glass tube; this was drawn out to a capil-
lary end ; the air was then expelled by heat, and the tube was
hermetically sealed. The tube was then placed in a vessel
covered with sand, heated to a full red-heat, and then suffered
to cool slowly. When the mass was taken out there was at
the bottom a regulus, which contained 63 per cent. of the an-
timony which had been added after it had been separated
from some adhering portions of sulphuret of antimony by
boiling with a little muriatic acid.

*¢ This had all the properties of pure antimony. Rubbed
to powder and boiled with muriatic acid, it still evolved how-
ever a little sulphuretted hydrogen and gave some antimony
to the acid. ‘The powder when thus boiled had lost 6} per
cent.

* From all this it is evident that though the resulting sul-
phuret of antimony contained more antimony after than be-
fore the process, it is not the combination which Faraday
thought it was. Even in the cleavage it had not the appear-

478 Ona supposed new Sulphate and Oxide of Antimony.

ance of a pure sulphuret of antimony. The upper portions
had the same radiated structure as the common sulphuret of
antimony, and a few larger crystals had shot up into the upper
surface of the regulus, where they were surrounded with an
irregular mass of a lighter colour. The upper and the lower
portions of this so-formed antimony were each separately
analysed, in such a manner that a weighed portion was put
into muriatic acid and digested in it in the water-bath. The
solution went on rapidly. From the lowermost portion cry-
stals fell off one after another, upon which the acid did not
act. The same happened likewise with the uppermost por-
tion, only they were smaller and fewer in number. ‘These in-
soluble parts when well boiled and washed were from the
lowermost 15 and from the uppermost 10 per cent. It
proved to be pure metallic antimony formed in feathery cry-
stals, and shows, therefore, the interesting fact that sulphuret
of antimony can dissolve at a high temperature 13} per cent.
of metallic antimony, which when the solution is suffered to
cool sufficiently slowly crystallizes out of the yet fluid sul-
phuret of antimony before this latter solidifies. By a more
rapid cooling the whole mass congeals together, and the cleav-
age is then quite similar throughout.

‘¢ From what has been said it is quite evident that the mu-
riatic acid takes up nothing but the common chloride of an-
timony. Ihave examined this behaviour further in detail,
and thereby found, that by this method neither with water
nor alkali is it possible to obtain any other oxide.

‘* The above-mentioned experiment of Faraday, that melted
oxide of antimony is decomposed by the electric current,
clearly proves that the law proposed by him that similar quan-
tities of electricity always evolve equal chemical proportions,
only holds good so long as the comparison is made between
combinations of proportional composition.

‘“‘ As for the cause of the appearance, that the decomposi-
tion of the oxide of antimony becomes gradually weaker and
weaker, and at last ceases, it is evident that Faraday has over-
looked the circumstance that the oxide is decomposed into
metal at the negative conductor and antimonious acid at the
positive conductor, which then soon becomes encrusted with
a solid substance, alter which the electricity could not have
any further action.” ~

With respect to Berzelius’s objection in the last paragraph
but one of his paper, I will ask you to reprint paragraph 821.*
of my series. ‘* All these facts combine into, I think, an ir-
resistible mass of evidence, proving the truth of the important

* See Lond. and Edinb, Phil. Mag., vol. v. p. 344.—Ebrr.

Mr. Nixon’s Table of observed Terrestrial Refractions. 479

proposition which I at first laid down, namely, that the che-
mical power of a current of electricity is in direct proportion
to the absolute quantity of electricity which passes. (377. 783.)
They prove too that this is not merely true with one substance,
as water, but generally with all electrolytic bodies ; and further
that the results obtained with any one substance do not merely
agree amongst themselves, but also with those obtained from
other substances, the whole combining together into one series
of definite electro-chemical actions.(505.) I do not mean to say
that no exceptions will appear ; perhaps some may arise, espe-
cially amongst substances existing only by weak affinity: but
I do not expect that any will seriously disturb the result an-
nounced. If, in the well-considered, well-examined, and I may
surely say, well-ascertained doctrines of the definite nature of
ordinary chemical affinity, such exceptions occur, as they do in
abundance, yet without being allowed to disturb our minds
as to the general conclusion, they ought also to be allowed, if
they should present themselves at this the opening of a new
view of electro-chemical action: not being held up as obstruc-
tions to those who may be engaged in rendering that view
more and more perfect, but laid aside for a while, in hopes
that their perfect and consistent explanation will finally ap-
pear.”

With regard to my having overlooked the cause of the
diminution and cessation of voltaic action on the oxide of
antimony, I do not know how that can well be said, for Ber-
zelius’s statement seems in parts to be almost a copy of the
reasons I have given: see paragraph 801. of the Seventh Series
of my Researches. My explanation is actually referred to in
the account of the action on the oxide of antimony at para-
graph 693., but by a misprint 802. has been stated instead
of 801.* I am, Gentlemen, yours &c.,

M. Farapay.

LXXXII. Table of observed Terrestrial Refractions. By
Joun Nixon, Esq.t
THE following table of mean refractions is founded on
measurements obtained at 61 stations on 162 arcs, of

various lengths from 1! 9" to 21! 48", amounting together to
17° 59’. The observations were made on 515 different days
of the years 1821 to 1824, 1827 to 1833, and 1835. The
average altitude above the level of the sea of the 162 arcs is
1730 feet.

* This reference is correctly made in Lond. and Edinb. Phil. Mag,, vol. y.
p. 170.—Epir.

+ Communicated by the Author.

480 Mr. Nixon’s Table of observed Terrestrial Refractions:

Table of observed Refractions.

11 arcs from |
\16' 36" to 2)’ 48”

fi

ose 29

— fi ps6

Perse 530
|

50 ares fi |

Sum, 162 ares = 17°58! 59"; Refr, 3425” = EES

The class A. forms itself naturally from the total deficiency
of observations on arcs from 14! 1" to 16! 36". That marked
B. consists of ares still large enough to mask those local irre-
gularities of refraction, generally of a negative character,
which begin to form an occasional but slight feature of the
class C. The arcs marked D, subdivided at first into two
classes of about the same number of arcs, were ranged together
on account of the anomaly of the smaller arcs presenting a
refraction of ;1,, whilst those of the other class, abounding in
negative refractions, averaged no more than ;+3. Some of
the more marked deviations from the mean value may, no
doubt, be attributed in inconsiderable distances to the want
of sufficient accuracy in the measurement of the height of the
eye and pointing the telescope at the base of the signal, yet
numerous recent observations have clearly indicated a modi-
fication of the average refraction peculiar to the locality. As
the ratio of the refraction to the contained are appears to
increase with the arc, it is more than probable that the con-
stant error of the sector, considered as — 20", has been esti-
mated in defect.

Let a,c be two arcs, of which c is (considerably) greater
than a, and let a third are & equal their difference c—a.

aie 1 :
Admitting =, to denote the constant proportion of the refrac-

, Abia :
tion to the arc, then will = be the refraction for the arc a, and

c A . .
= that for the are c; that of the intermediate arc } being

1 Cc
equa to ~

a . : °
a Supposing the instrument to give the ele-

Mr. Blackwall on undescribed Species of Araneide. 481
vations in defect by an unknown constant quantity 2, the

: ; a
calculated refraction for the are a will be —~ -% and that

See ; : -
for the arc C, ple Hence the ¢rue refraction for the in-

termediate arc 6 must equal the difference of these two quan
tities, and the constant error of the instrument will be the
excess of this proportion of the are c (or a) above the quantity
previously calculated.

The several values of the refraction in terms of the arc, and
that of the error of the instrument, deduced from the applica-
tion of the above formula to various combinations of the four
classes of arcs, are subjoined.

Ref. Error of
er,

Sector.

I. By the difference of Band A... j1, —24/
ii. Cand A... 737 —23
II], -——_—_————- DandA... , -26
Iv, ———---——— DandB... zi5 —27.

The true value of the mean refraction is most probably the
average of the two first ratios, or ;1.,, and that of the in-
strumental error 23}", or about 2" more than the quantity de-
rived from actual measurement. (See Lond. and Edinb. Phil.
Mag. for 1833, vol. ii. page 334.)

Ilkley, April 27, 1836. Joun Nrxon.

LXX XIII. Characters of some undescribedSpecies of Araneidz.
By Joun Brackwatt, Esq., F.L.S., §c.*

Tribe, Tuxsire_x, Latreille.
Genus, Walckenaéria hi
7 galls - 1nl.
Walckenaéria fuscipes,
EPHALOTHORAX oval, convex and glossy, with a slight indentation
in the medial line cf the posterior region; the anterior part, which
is prominent and acute, is compressed and deeply indented on the sides,
and has also a slight longitudinal indentation above: in front it is divided
into two segments by a transverse groove. Mandibles conical, armed with
teeth on the inner surface, and inclined towards the pectus, which is broad
and heart-shaped. Legs moderately robust; the anterior and posterior
pairs, which are the longest, are equal in length, and the third pair is the
shortest. ‘These parts, with the maxille and lip, are of a brown colour ;
palpi brown, the fourth and fifth joints being much the darkest ; the fourth
joint terminates in two apophyses ; one, which is large, depressed, and hairy
externally, overlaps the base of the fifth joint; the other, which is small,
projects on the inner side; the fifth joint is oval, convex and hairy ex-
ternally, concave within, comprising the palpal organs; they are highly

* Communicated by the Author.

Third Series. Vol. 8. No. 49. June 1836. 3C

482 Mr. Blackwall on undescribed Species of Araneide.

developed, not very complex in structure, and are of a brown colour
tinged with red. Eyes distributed in pairs on the anterior eminence of
the cephalothorax; one pair is situated on the summit of its superior seg-
ment, another on a small prominence on the upper part of the inferior
segment, in front ; these eyes describe a narrow trapezoid whose shortest
side is before; the third and fourth pairs are seated on the sides of the
frontal eminence, and are geminated. Each tarsus is terminated by three,
claws ; the two upper ones are pectinated, and the lower one is inflected
near its base. Abdomen oval, convex above, projecting over the base of
the cephalothorax ; it is thinly covered with hair, glossy, and of a brownish
black colour. The plates of the spiracles are pale yellow.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, ,th of an inch; length of the cephalothorax ,; breadth
s+; breadth of the abdomen ;*,; length of an anterior leg +4; length of
a leg of the third pair +4.

I found this spider in March 1835, at Oakland, under stones; but ob-
tained specimens of males only. ‘

Walckenaéria depressa.

Cephalothorax of a short oval form, convex, prominent, but obtuse,
before, where the eyes are situated, depressed in the posterior region,
without any indentation in the medial line. Mandibles moderately strong, -
concave, and slightly inclined towards the pectus, which is broad and
heart-shaped. The anterior and posterior pairs of legs, which are the
longest, are equal in length, and the third pair is the shortest. These
parts, with the maxille and lip, are of a deep brown colour, the cephalo-
thorax, pectus, and lip being much the darkest. Each tarsus is terminated
by three claws; the two superior ones are curved and pectinated, and the
inferior one is inflected near its base. The third and fourth joints of the
palpi are short; the latter is the larger, and has two strong apophyses in
front, the outer one of which is the more prominent: the fifth joint is oval,
convex and hairy externally, ccricave within, comprising the palpal organs ;
they are highly developed, complicated in structure, with a curved, spiny
process at the extremity, and are of a deep red-brown colour. Abdomen
oval, somewhat depressed, pointed at the spinners, and projects over the
base of the cephalothorax; it is thinly covered with hair, glossy, and
brownish black. Plates of the spiracles deep brown. Aged individuals
have the legs of a dark red-brown colour.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, +;th of an inch; length of the cephalothorax ,; breadth
sz; breadth of the abdomen ~,; length of an anterior leg +-; length
of a leg of the third pair +4.

The specimens from which the description was made were taken under
stones, in a wood at Oakland, in April 1835. Males alone were cap-
tured.

Walckenaéria obtusa.

There is a striking resemblance between the male of this species and the
male of Walckenaéria cuspidata* ; the following are the principal points of
difference. The male of Walckenaéria obtusa is decidedly the larger, its
pectus is more elongated, it has a slight indentation in the medial line
of the posterior region of the cephalothorax, and has no acute, conical
prominence situated within the trapezoid formed by the four intermediate

* For the description of Walckenaéria cuspidata, see Lond. and Edinb.
Phil. Mag., vol. iii. p. 108,

Mr. Blackwall on undescribed Species of Araneide. 483

eyes. Its palpi also differ a little in organizaticn : the third joint is clavate ;
the fourth is short, terminating in three apophyses, the largest of which
curves outwards before the fifth joint; exterior to this occurs the next in
size, having a small, pointed prominence at its base, in front; and the
smallest is situated underneath: the fifth joint is somewhat oval, convex
and hairy externally, concave within, comprising the palpal organs; they
are highly developed, complicated in structure, with a strong spine on the
outer side curved into a circular form, and are of a brownish black colour
tinged with red.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, +th of an inch; length of the cephalothorax +, ; breadth
z'y; breadth of the abdomen +',; length of an anterior leg #,; length of
a leg of the third pair 2.

I found males of this species under stones at Oakland in February 1835,
but I have not been so fortunate as to discover the female.

Tribe, INEQUITEL”, Latreille.
Genus, Theridion, Walckenaer.
Theridion angulatum.

Cephalothorax inversely heart-shaped, inclining to oval, convex, slightly
hairy, prominent before, where the eyes are situated, with an inden-
tation in the medial line of the postericr region ; its colour is pale yellow-
brown, with a longitudinal band ef red-brown on each side, and a broader
one of the same hue extending along the middle ; the margins are yellowish
white. Eyes placed on black spots; four, which are intermediate, form
a square nearly, the two in front being seated on a protuberance ; the
other four are disposed in pairs on the sides of the square; the eyes con-
stituting each pair are placed obliquely on an eminence, and are near
together but not contiguous. Mandibles moderately strong, conical, and
perpendicular; they are red-brown, with a spot of a darker hue in front,
near the base of each. Maxillze enlarged externally, where the palpi are
inserted, obliquely truncated on the outer side, at the extremity, and in-
clined towards the lip, which is almost semicircular, being a little pointed
at the apex. These organs, and the palpi, which are short, and are armed
with a curved, pectinated claw at the extremity, are of a red-brown colour.
Pectus of an oblong heart-shape and a dark red-brown hue. Legs yel-
lowish-brown banded with red-brown; the first pair is the longest, then
the fourth, the third pair being the shortest; the second and third pairs
are disproportionally short. Each tarsus is terminated by three claws;
the two superior ones are curved, and are slightly pectinated near the base,
and the inferior one is inflected near its insertion. The abdomen, which
is deeply notched in front, and projects over the base of the cephalotho-
rax, has an angular appearance, occasioned by two, bold, lateral promi-
nences, situated on the upper side, nearer to the posterior than the an-
terior extremity; the superior surface, from the fore part to the lateral
prominences, is of a deep red-brown colour, the margins being the darkest ;
on each side of the medial line are two minute, yellowish white spots,
forming a long narrow quadrangle; the posterior part is pale red-brown,
a yellow transverse line connecting the two lateral prominences, from
which proceed two obscure, angular bands that converge to the spinners ;
the whole of the upper part has an irregular border of yellowish-white
minutely freckled with red-brown; the sides and under part of the abdo-
men are dark red-brown, with streaks and minute spots of a lighter shade.
Plates of the spiracles yellow.

Length, from the anterior part of the cephalothorax to the extremity of

3C2

484 Mr. Blackwall on undescribed Species of Araneidee.

the abdomen, +th of an inch; length of the cephalcthorax :,; breadth
a'y; breadth of the abdomen ;; length of an anterior leg +; length of a
leg of the third pair 4.

This spider, which, like Tetragnatha extensa, frequently extends the first
and second pairs of legs forwards, and the third and fourth pairs back-
wards, in a line with the body, was found in a cleft of a rail at Oakland,
in the month of April, 1835. I have not yet seen the male.

Theridion filipes.

This remarkable species has the cephalothorax of an oval form; it is con-
vex and glossy, with an indentation in the medial line of the posterior re-
gion. Mandibles powerful, conical, armed with teeth on the inner surface,
rather divergent at the extremities, and inclined towards the pectus, which
is heart-shaped. Maxillee enlarged at the base, where the palpi are in-
serted, obliquely truncated on the outer side, at the extremity, and in-
clined towards the lip, which is semicircular, and prominent at the apex.
Legs and palpi long, slender, and furnished with hairs and some fine, erect
spines. These parts are of a brown colour, the mandibles and maxillz
having a tinge of red. Eyes disposed in two transverse rows on the fore
part of the cephalothorax; the intermediate eyes of both rows form a
trapezoid whose anterior side is considerably the shortest; the lateral
ones are placed obliquely in pairs, each pair being seated on a small emi-
nevice, and geminated ; the posterior eyes of the trapezoid are larger, and
the anterior ones much smaller than the rest. Each tarsus is terminated
by three claws ; the two superior ones are curved and slightly pectinated,
and the inferior one is inflected near its base. The first pair of legs is the
longest, then the fourth, the third pair being the shortest. Abdomen oval,
convex above, projecting over the base of the cephalothorax; it is thinly
covered with hair, glossy, and of a blackish brown colour, with a tinge of
olive. A long, slender, cylindrical, semitransparent process, directed back-
wards, is in connexion with the sexual organs. Plates of the spiracles of a
deep, dull brown colour. Some specimens have a series of faint, pale, an-
gular lines, whose vertices are directed forwards, extending along the mid-
dle of the upper part of the abdomen.

Length, from the anterior part of the cephalothorax to the extremity
of the abdomen, 3th of an inch; length of the cephalothorax 5; breadth
23 breadth of the abdomen +',; length of an anterior leg 2%, ; length of
a leg of the third pair -3,.

The male is rather smaller and darker coloured than the female, but the
relative length of its legs is the same; their absolute length, however, is
greater, an anterior one measuring }4ths of an inch. The third and fourth
Joiuts of the palpi are short; the latter, which is the stronger, being pro-
minent on the inner side and in front; with the frontal prominence se-
veral long bristles are connected: the fifth joint is of a long, irregular
oval form, having a projection on the outer side, and two smaller ones on
the upper part, near its articulation with the fourth joint; it is convex
and hairy externally, concave within, comprising the palpal organs, which
are highly developed, complicated in structure, and of a red-brown colour;
a strong, corneous spine, enveloped in a delicate, transparent membrane,
originates in the upper part of these organs, and, bending downwards, ex-
tends along their inner side a little beyond the termination of the fifth
joint, being curved outwards at its extremity.

This spider is allied to the Neriene by the disposition and relative size
of the eyes, and to the Linyphie by the length and delicacy of its limbs ;
indeed, on a superficial view, it bears a striking resemblance to Linyphia
pusilla ; but the structure of the maxilla and the relative length of the

Mr. Blackwall on undescribed Species of Araneide. 485

legs have induced me to class it with the Theridia. It occurs under stones
in the woods at Oakland, where I captured specimens in March 1835.

The first individual I examined under the microscope was a female, and
it presented an anomaly in organization which I never before witnessed
in this class of animals ; it had a supernumerary eye, situated between the
two small ones constituting the anterior pair of the trapezoid. An in-
stance of a deficiency of eyes in a female Thomisus cristatus has since
fallen under my observation. This spider had the two lateral pairs only ;
the two intermediate, or smaller pairs, were altogether wanting, not even
the slightest rudiments being visible.

Genus, Neriene, oT
‘ : mihi.
Neriene rubripes,

Cephalothorax oval, convex, glossy, with furrows on the sides diverging
from the upper part to the margins, and an indentation in the medial line
of the posterior region. Mandibles powerful, conical, convex in front,
divergent at the lower extremities, armed with two rows of teeth on the
inner surface, and slightly inclined towards the pectus, which is heart-
shaped. Maxilla strong, and inclined towards the lip, which is semicir-
cular and prominent at the apex. These parts are of a red-brown colour,
the mandibles, lip, and margins of the pectus being the darkest. Legs mo-
derately robust, provided with hairs and a few fine spines; the first pair is
rather the longest, then the fourth, the third pair being the shortest.
These organs and the palpi are of a red colour. Each tarsus has three
claws at its extremity; the two superior ones are pectinated about two
thirds of their length from the base, and the inferior one is inflected near
its insertion, Eyes placed on black spots, and disposed as in the Neriene
generally. Abdomen oval, convex above, projecting over the base of the
cephalothorax ; it is thinly covered with hair, glossy, and brownish black.
Plates of the spiracles pale yellow. A curved process of a red-brown
colour is connected with the sexual organs. Some individuals have the
abdomen of a yellowish-brown hue, and the other parts, generally, lighter-
coloured.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, .%,ths of an inch; length of the cephalothorax ~, ; breadth
a's breadth of the abdomen ;',; length of an anterior leg +; length of
aleg of the third pair ~,.

The male is somewhat smaller and darker-coloured than the female,
but its legs are longer, an anterior one measuring ~%ths of an inch. The
maxille are remarkably convex externally immediately before the insertion
of the palpi. The second joint of the palpi is curved towards the cepha-
lothorax; the third and fourth joints are short, the latter being rather the
larger: the fifth is oval, convex and hairy externally, concave within, com-
prising the palpal organs, which are prominent, highly developed, complex
in structure, and are of a dark red-brown colour. ‘The fifth or terminal
joints of the palpi have their convex sides directed towards each other.

This species was found at Oakland, under stones, in the autumn of 1834,
by Mr. T. Blackwall.

Neriene tibialis.

This spider has the cephalothorax of an oval form; it is convex, glossy,
prominent but obtuse before, where the eyes are situated, with an indenta-
tion in the medial line of the posterior region. Mandibles moderately

owerful, conical, armed with teeth on the inner surface, and somewhat
inclined towards the pectus, which is heart-shaped. ‘These parts, with

486 Mr. Blackwall on undescribed Species of Araneide.

the maxillz and lip, are of a brownish black colour. The anterior and
posterior pairs of legs, which are the longest, are equal in length, and the
third pair is the shortest. Each tarsus is terminated by three claws; the
two superior ones are slightly pectinated, and the inferior one is inflected
near its base. The tibize of the anterior pair of legs are disproporticnally
strong, having the appearance of being swoln. The palpi are slender ; the
third joint is long and clavate; the fourth is elongated before into a nar-
row, oval process, hairy externally, which extends obliquely across the
upper part of the fifth joint towards the inner side, but is terminated by a
short, acute spine curved outwards: the fifth joint is oval, convex and
hairy externally, concave within, comprising the palpal organs, which are
highly developed and complicated in structure, having several corneous
processes, one of which, on the outer side, at the extremity, is curved
into a cireular form. Abdomen oval, convex above, projecting over the
base of the cephalothorax ; it is thinly covered with hair, glossy, and of a
brownish black colour. The plates of the spiracles are pale yellow.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, ~-th of an inch; length of the cephalothorax »,; breadth
5; breadth of the abdomen ;!,; length of an anterior leg +; length of a
jeg of the third pair 3.

{In March 1835 I captured a few specimens of this species, all of which
were males, under stones, at Oakland.

Neriene livida.

Cephalothorax oval, convex, glossy, with several furrows on the sides
diverging from the middle to the margins, and an indentation in the medial
line of the posterior region. Mandibles powerful, conical, convex in front,
near the base, armed with a few small teeth on the inner surface, and
rather inclined towards the pectus, which is heart-shaped. Maxillz strong,
convex underneath, and inclined towards the lip, which is somewhat of a
triangular form truncated at the apex. Legs and palpi robust, and fur-
nished with hairs and fine spines. These parts are of a red-brown colour,
the lip, maxilla, mandibles, and anterior part of the cephalothorax being
the darkest. Each tarsus is terminated by three claws; the two superior
ones are curved and deeply pectinated, and the inferior one is inflected
near its base; the palpi have a curved, pectinated claw at the extremity.
Abdomen oval, convex above, projecting over the base of the cephalotho-
rax, and rather broader at the posterior than the anterior extremity ; it
is thinly covered with hair, glossy, and of a yellowish-brown colour, with
a tinge of black. Plates of the spiracles pale-yellow. ;

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, ith of an inch; length of the cephalothorax 5',; breadth
~'y; breadth of the abdomen yz; length of an anterior leg +; length of
a leg of the third pair +.

The male is smaller and darker coloured than the female, but the rela-
tive length of its legs is the same. The second joint of the palpi is curved
towards the cephalothorax; the third and fourth joints are short, the
latter projecting two obtuse apophyses, the larger one situated on the
outer and the smaller one on the inner side: the fifth joint is oval, convex
and hairy externally, concave within, comprising the palpal organs, which
are highly developed, complex in structure, and of a dark red-brown colour.

This species is common on the under surface of stones in the neighbour-
hood of Llanrwst.

Neriene furva.

The cephalothorax is of an oval figure; it is convex, glossy, with slight
furrows on the sides, and an indentation in the medial line of the posterior

Mr. Blackwall on undescribed Species of Araneidze. 487

region. Mandibles powerful, conical, vertical, convex in front, and armed
with teeth on the inner surface. Maxille enlarged at the base, where the
palpi are inserted, and inclined towards the lip, which is semicircular and
prominent at the apex. Pectus heart-shaped. These parts are dark brown,
with a slight tinge of red, the pectus, lip, and anterior part of the cepha-
lothorax being the darkest. Legs and palpi robust, and of a red colour.
Each tarsus is terminated by three claws; the two superior ones are pec-
tinated about half their length from the base, and the inferior one is in-
flected near its insertion. The third and fourth joints of the palpi are
short, the former, which is considerably the stronger, being convex in front ;
the latter projects two apophyses from its anterior extremity ; ene before,
which terminates in a corneous point, and has a small, acute, corneous
prominence on the inner side; the other underneath, which is provided
with a corneous point on the outer side: the fifth joint is oval, convex and
hairy externally, concave within, comprising the palpal organs; they are
highly developed, complicated in structure, with a corneous process at the
upper part curved outwards, and are of a dark red-brown colour. Ab-
domen oval, convex above, projecting over the base of the cephalothorax ;
it is thinly covered with hair, glossy, and of a brownish-black colour.
Plates of the spiracles pale yellowish-white.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen 3th of an inch; length of the cephalothorax ;-; breadth 3, ;
breadth of the abdomen -~, ; length of an anterior leg +; length of a leg
of the third pair +.

I found one male only of this species, under a fragment of rock in a
wood at Oakland, in June 1835.

Tribe, ORBITELE, i
Genus, Linyphia, \ Latreille.

Linyphia nigella.

Cephaiothorax oval, convex, glossy, with an indentation in the medial
line of the posterior region; it is of a dark brown colour approaching to
black. Mandibles long, powerful, armed with teeth on the inner surface,
divergent at the extremities, of a deep brown colour tinged with red, and
inclined towards the pectus, which is heart-shaped, and of a brownish black
hue. Maxille strong, longer than broad, with the exterior angle, at the
extremity, curvilinear; they resemble the mandibles in colour, and incline
a little towards the lip, which is semicircular, prominent at the apex, and
brownish black. Legs long and slender, provided with hairs and a few
spines; their colour is pale yellowish brown, the thighs having a tinge of
red. Each tarsus is terminated by three claws; the two superior Ones are
curved and pectinated, and the inferior one is inflected near its base.
Eyes disposed in two transverse rows on the anterior part of the cephalo-
thorax ; the intermediate eyes of both rows form a trapezoid, whose an-
terior side is considerably the shortest, and the lateral ones are placed
obliquely in pairs, each pair being seated on a small eminence, and gemi-
nated ; the posterior eyes of the trapezoid are the largest, and the anterior
ones much the smallest of the eight. The third and fourth joints of the
palpi are short, the latter, which is much the stronger, being prominent on
the inner side, at the lower extremity: the fifth joint is of an irrregular
oval figure, convex and hairy externally, concave within, comprising the
palpal organs, which are highly developed, complicated in structure, having
a small projection at the upper part, in front, and a large corneous spine,
originating in the upper part of the under side, extending to the termina-
tion of the joint, where it is curved into a circular form, the extremity
projecting a little; the colour of these organs is dark reddish brown,

488 Mr. Blackwall on undescribed Species of Araneide.

The convex sides of the fifth or terminal jvints of the palpi are directed
towards each other. Abdomen oval, convex above, projecting over the
base of the cephalothorax; it is thinly covered with hair, glossy, and
brownish black. Plates of the spiracles pale yellowish brown. Some in-
dividuals have a series of obscure, angular lines of a yellowish brown co-
lour, whose vertices are directed forwards, extending along the middle of
the upper part.

. Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, 4th of an inch; length of the cephalothorax +; ; breadth
2,3 breadth of theabdomen ~,; length of an anterior leg +4; length of
a leg of the third pair 3.

Specimens of this species were procured under fragments of rock in the
woods at Oakland, in September 1835, but they were all males.

Linyphia tardipes.

The cephalothorax of this interesting species is oval, convex, glossy, de-
pressed and somewhat rounded before, with an indentation in the medial
line of the posterior region; its colour is reddish brown, with a broad band
of blackish brown extending along each side. Mandibles powerful, conical,
divergent at the extremities, and inclined towards the pectus; they are
terminated by a long nail slightly curved at its extremity, and are armed
with two rows of teeth cn the inner surface, the anterior row being re-
markably long and fine. Maxille strong, straight, and somewhat quadrate,
having the exterior angle, at their extremity, curvilinear. Lip semicircular
and prominent at the apex. The pectus, which is heart-shaped, is finely
pointed at its posterior extremity. These parts are of a reddish brown
colour, the pectus and lip being rather the darkest. Eyes placed on black
spots on the anterior part of the cephalothorax; four are intermediate
and form a square nearly, the two in front being the largest of the eight ;
the other four are disposed in pairs on the sides of the square; the eyes
constituting each pair are placed obliquely on a small eminence, and are
contiguous. The palpi are furnished with spines, and have a slightly
curved, slender claw at their extremity; their colour is reddish brown.
Legs moderately robust, supplied with hairs and a few fine, erect spines ;
they are of a reddish brown colour obscurely banded with brownish black ;
the first pair is the longest, the second and fourth pairs are nearly equal
in length, and the third pair is the shortest. Each tarsus is terminated by
three claws ; the two superior ones are curved, and the inferior one is in-
flected near its base. Abdomen oval, convex above, rather broader at the
posterior than the anterior extremity, and projects over the base of the
cephalcthorax ; it is thinly covered with hair, glossy, and of a reddish
brown colour on the upper side with a few minute, whitish spots inter-
spersed, and a series of large, brownish black blotches extending along each
side of the medial line ; these blotches unite, as they approach the spinners,
and form transverse, curved bands; the sides are brownish black, minutely
mottled with reddish brown; the under side is dark brown, or brownish
black. Plates of the spiracles pale yellow. Connected with the sexual organs
is a large and very prominent, curved process of a dark red-brown colour ;
it is abruptly contracted in the curvature, and is recurved at the extremity,
which is enlarged and deeply notched.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, 4th of an inch ; length of the cephalothorax ,; breadth 7, ;
breadth of the abdomen +';; length of an anterior leg ,4, ; length of a leg
of the third pair 4.

The male resembles the female in colour, and in the relative length of
the legs, but their absolute length is greater, an anterior one measuring

__ ms

Mr. Blackwall on undescribed Species of Araneid&, 489

3#,ths of an inch. On the anterior part of the cephalothorax, about the
region of the eyes, are some longish, black bristles, directed forwards.
The third and fourth joints of the palpi are short, the latter being the
stronger, and a long, slender bristle projects in front from the anterior ex-
tremity of the former: the fifth joint is somewhat oval, being gibbous on
the outer margin, and having a large process, or apophysis, curved out-
wards, and notched at its extremity, directed upwards from its superior
part; it is convex and hairy externally, concave within, comprising the
palpai organs, which are highly developed, complex in structure, present-
ing several curved, corneous processes, and are of a red-brown colour.
The fifth joints of the palpi have their convex sides turned towards each
other.

In the autumn of 1834, I found specimens of this spider at Oakland,
under detached pieces of rock imbedded in a light soil, to the inferior
surface of which they attach their cocoons, usually two or three in number,
by asmall, fine web. The cocoon is flat on the side in contact with the rock,
and convex, with a smail, depressed border, on the opposite one. It measures
about 4th of an inch in diameter, is composed of white silk of a fine com-
pact texture, and contains, on an average, between thirty and forty sphe-
rical eggs of a pale yellow colour, not agglutinated together, but enveloped
in delicately soft silk. This species fabricates a small, compact, horizontal
sheet of web in the cavities beneath stones, on the under side of which it
takes its station in an inverted position. It pairs in the month of Sep-
tember. An approximation to the Theridia may be traced in the dispo-
sition and relative size cf the eyes.

Tribe, LatTericrap&, Latreille.

Genus, Thomisus, Walckenier.
Thomisus luctuosus.

Cephalethorax inversely heart-shaped, convex, depressed in the pos-
terior region, and broadly truncated before; it is of a brown colour, veined
with lines of a deeper shade, and hasa fine line of yellowish white on the
lateral margin; a short band of a yellowish white hue, bifid before, on
each side of which is a spot of the same colour, situated on an irregular,
black patch, occupies the medial line of that portion of the cephalothorax
which is in contact with the abdomen, and a faint brownish white spot oc-
curs on the inner side of the tubercles on which the anterior eyes of the
lateral pairs are seated. Eyes disposed in front, in two transverse, curved
rows, forming 2 crescent ; the lateral eyes of both rows are larger than the
rest, those of the anterior row being the largest of all, and are situated on
projections of the cephalothorax. Mandibles short, strong, vertical, cunei-
form. Maxille inclined towards the lip, which is triangular. Pectus ob-
long heart-shaped.. These parts, with the legs and palpi, are of a dark
brown colour, the legs being streaked and spotted with brown of a deeper
shade, and yellowish white at the joints. The first and second pairs of legs,
whose dimensions considerably exceed those of the third and fourth pairs,
are nearly equal in length, the second pair being slightly the longer ; and
the longitudinal extent of the fourth pair surpasses that of the third. Each
tarsus has two curved, deeply pectinated claws at its extremity. Abdomen
oval, depressed, wrinkled, broader at its posterior than its anterior ex-
tremity, and projects over the base of the cephalothorax ; its colour is
dark brown obscurely mottled with pale brown and yellowish white, parti-
cularly on the upper part. Plates of the spiracles reddish brown.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, 4th of an inch; length of the cephalothorax 4th; breadth

Third Serics. Vol. 8. No. 49. June 1836. 3D

490 Mr. Blackwall on undescribed Species of Araneidze.

tx; breadth of the abdomen +; length of a leg of the second pair 4;
length of a leg of the third pair 4.

I discovered the female of this species, which seems to belong to the
section Cancroides, in September 1834, in the woods at Oakland, on the
trunks of trees which had been felled. In July it constructs a lenticular
cocoon of white silk, of a compact texture, measuring about 4th of an inch
in diameter, in which it deposits between 80 and 90 spherical eggs, of a
pale yellowish white colour, not agglutinated together. The cocoon is
often placed between two leaves connected by a slight tissue of silk, form-
ing a kind of sack, usually containing the female, which sits upon the
cocoon and is greatly attached to it.

Tribe, CITIGRADZ, Lege
Genus, Lycosa,

Lycosa exigua.

Cephalothorax large, hairy, somewhat oval, compressed before, with de-
pressed, sloping sides, and a narrow indentation in the medial line of the
posterior region; its colour is dark brown, with three longitudinal bands
of a pale yellowish brown tint, one extending along each side, and the
third occupying the carina. Mandibles strong, conical, armed with a few
teeth on the inner surface, reddish brown, and inclined towards the pectus,
which is heart-shaped, of a very dark brown colour, approaching to
black, and is thinly covered with whitish hairs. Maxillz short, powerful,
straight, enlarged and rounded at the extremity, and of a pale reddish
brown colour. Lip quadrate, and of a dark, dull brown colour, being palest
at the apex. Eyes unequal in size; four, which are minute, form a row
in front, the two exterior ones being the smallest; the other four are
placed on the sides of the anterior part of the cephalothorax, and form a
square nearly, the anterior pair being the largest of the eight. Legs and
palpi long, moderately robust, and provided with hairs and strong spines ;
they are of a pale reddish brown colour, with spots and longitudinal streaks
of a brownish black hue on the upper part and sides; these spots and
streaks are most conspicuous on the thighs, and on the second joint of the
palpi. The palpal claw is curved and pectinated. Each tarsus has two
curved, deeply pectinated claws at its extremity. Abdomen oval, hairy,
convex above, projecting over the base of the cephalothorax ; it is dark
brown on the upper side, with three yellowish white spots in front, the
intermediate one, which is the largest, and is faintly bordered with brownish
black, extending backwards nearly half the length of the abdomen; on
each side of the medial line, on the posterior half of the abdomen, occurs
a series of alternate blackish and white spots, the latter being much the
smaller; the two series, which are rather obscure in some specimens, con-
verge to the spinners, where they meet; the sides are yellowish brown,
spotted with dark brown; the under side is pale yellowish, or reddish
brown. Plates of the spiracles very dark brown.

Length, from the anterior part of the cephalothorax to the extremity of
the abdomen, 1th of an inch; length of the cephalothorax 4; breadth 5; ;
breadth of the abdomen +',; length of a posterior leg 44.; length of a leg
of the third pair 53,.

The male is rather smaller than the female, and darker coloured, but the
relative length of its legs is the same. The third and fourth joints of the
palpi are short, the latter being the stronger of the two: the fifth joint is
oval and pointed at the extremity, which is armed with a small claw; it is
convex and hairy externally, concave within, except at the end, which
is solid, and comprises the palpal organs; they are highly developed, com-

The Rey. P. Keith on the Conditions of Germination. 491

plex with corncous processes, and are of a very dark reddish brown co-
lour.

This species occurs in pasture fields in Denbighshire. In the month of
June the female spins a lenticular cocoon of yellowish or greenish brown
silk, of a compact texture, with a whitish margin of a slighter texture ; it
contains between 50 and 60 yellowish white eggs of a spherical figure, not
agglutinated together. The cocoon, which is always connected with the
spinners of the female, and is carried along with her, measures about jth
of an inch in diameter; when the young quit it they attach themselves
to the body of the mother.

Oakland, Denbighshire, 1836.

LXXXIV. Of the Conditions of Germination, in reply to
M. DeCandolle. By the Rev. P. Ketru, £.L.8.*

OTHUING can be so gratifying to an author as the com-
mendation that comes from a critic of acknowledged ta-
lent and learning—* laudatus d laudato viro.” But we, the
oi moaaos of botanical scribblers, ought, perhaps, to rest satis-
fied, and to think ourselves very well off if a first- or second-
rate wrangler in the science condescends to take notice of
us, if it were but for the purpose of giving us a rap on the
knuckles.

In my System of Physiological Botany published in 1816+,
I enumerated five conditions as necessary to the process of
the germination of the seed, and thought I had adduced good
grounds for the said enumeration. Yet its accuracy has been
impugned by a great botanist, and my five conditions reduced
to three. I ought, perhaps, to submit in silence, and take in
good part the correction of a great master; but as I am not
satisfied of the soundness of the views of my corrector, I will
venture to vindicate my original statement.—Proceed we now
to the article itself.

I. The first condition necessary to germination is the ma-
turity of the seed. Unripe seeds seldom germinate, because
their parts are not yet prepared ta form the chemical combi-
nations on which germination depends. ‘This fact M. De
Candolle denies, saying that “ M. Keith ne sest pas ex-
primé avec precision lorsqu’il a posé la maturité de la graine,
pour premiere condition générale et nécessaire a la germina-
tion”; and adding that Senebier and ‘Treviranus succeeded
in making green peas to germinate a short time before they
were absolutely ripet{. If M. DeCandolle had read to the end
of the paragraph which he criticizes, he would have seen that
the identical exception which he specifies is mentioned by

* Communicated by the Author.
+ Vol. ii. p. 3. { Phys. Veg. il. 662.

492 The Rev. P. Keith on the Conditions of Germination,

Mr. Keith. He would have seen also that radish-seed, which
M. Lefébure could not prevail upon to germinate till it was
quite ripe, will germinate, when it pleases to do so, before
that period arrives. If left long upon the stalk in a wet sea-
son it will germinate even in the pod. Also Jemon-seed will
sometimes germinate in the very centre of its pulpy pericarp
even before the fruit is cut open.

After all, we regard these apparent exceptions as amounting
absolutely to nothing. The seeds were not ripe, it is true, in
the common acceptation of the term, which supposes them to
be as dry and as hard as a bone; but they were ripe in the
physiological acceptation of it, and that is enough. ‘The seed
that will germinate is, physiologically speaking, ripe; that is,
its fluids have been so elaborated in the process of its matura-
tion, and its solids so vitalized in the assimilation of due aliment,
as to be now fully and profitably susceptible of the action of
the combined stimuli of the soil and atmosphere. Hence I
contend, notwithstanding the objection of M. DeCandolle, that
the maturity of the seed is rightly and legitimately placed in
the list of the conditions of germination. I do not speak of
the experiments of the chemist in bis laboratory; I do not
deny that a seed apparently unripe may germinate; but I
speak of the operations of the farmer and of the gardener, and
ask whether or not it would not be thought most absurd in them
if they were to gather and sow their seeds in an unripe state?

II. The second condition necessary to germination, or at
least to rapid and healthy germination, is the exclusion of
light. The practice of the raking in of the grains, or seeds,
sown by the farmer or gardener is founded upon this principle.
But it does not seem to have engaged the notice of men of
science, or to have heen proved by direct and intentional ex-
periment till lately. The first direct experiments that were
instituted on this subject are those of Ingenhousz. He found
that seeds germinate faster in the shade than in the sun, and
hence concluded that light is prejudicial to germination. Se-
nebier, who repeated the experiments of Ingenhousz, had the
same result, and drew from them the same conclusion*.
The prejudicial effect of light has been thought to be owing
to its action on the carbonic acid gas contained in the seed,
by which its oxygen is withdrawn too rapidly, its carbon
fixed, its mass parched, and the possibility of its germination
thus precluded. _

But M. DeCandolle denies that the exclusion of light is
necessary: L’exclusion de Ja lumiére est trés-loin d’étre,

* Mem. Phys. Chem. vol. ili. p. 341.

in Reply to M. DeCandolle. 493

comme on la dit *, unedes conditions nécessaires a la germina-
tion: il n’y a personne, en effet, qui n’ait vu des graines ger-
mer, quoique exposées a la clarté ft.” Yet this objection is
equally invalid with the objection that was made to the
maturity of the seed. I do not say that a seed may not ger-
minate if left exposed to the light. I do not say that it may
not be made todo so. _ But is that giving it a fair chance for
early and healthy germination? Is that treating it in a way
to bring all toasuccessful issue? For, again, I allude merely
to the operations of the farmer and gardener, and not to the
experiments of the chemist in his closet ; though I am ready
to admit that there is, perhaps, no rule without its exception ;
and on this ground it will be easy to find a flaw in almost any
rule whatever. Suppose a writer on agriculture were to say
that it is necessary for the cultivator who would farm well
to keep his corn-fields clear of weeds; the truth of the rule
might be denied by any one who was disposed to be captious.
For he may turn round upon the rale-maker, and say,— No
such thing! What you advance is not the fact, for I have
seen many a good crop of corn in fields where the weeds stood
higher than the corn itself. This may be all very true; but
would it be a good and valid objection against the keeping of
corn-fields clear of weeds? Certainly not. What then are
we to think of the objections with which M. DeCandolle com-
bats the accuracy of the above conditions of germination ?
For in the one case he admits that the grains selected for sow-
ing should be the largest and the best nourished,—but how
can they possibly be so, unless they are left upon the stalk
till they are fully ripe?—and in the other case he does not
deny that the exclusion of light is useful to germination, he
only denies that it is necessary. But if it can be shown to
be useful, we maintain that it is on that very account practi-
cally necessary.

III. <A third condition of germination is the access of a
certain degree of heat. No seed has ever been known to ger-
minate at or below the freezing-point. Hence seeds do not
generally germinate in winter, even though lodged in their
proper soil. Yet the potential vitality of the seed is not
necessarily destroyed by this exposure. For the seed will
germinate still, on the return of spring, when the ground has
been again thawed, and the temperature raised to the proper
degree. ‘This condition M. DeCandolle admits to be good,

[V. A fourth condition necessary to germination is the ac-
cess of moisture. Seeds will not germinate if they are kept

* Keith, Phys. Bot., vol. ii. p. 5. + Phys. Vég., ii. 638.

494 The Rev. P. Keith on the Conditions of Germination.

perfectly dry. Water, therefore, or some liquid equivalent
to it, is essential to germination. Hence rain is always ac-
ceptable to the farmer or gardener immediately after he has
sown his seed; and if no rain falls, recourse must be had if
possible to artificial waterings. But the quantity of water ap-
plied is not a matter of indifference. There may be too little
or there may be too much. If there is.too little, the seed dies
for lack of moisture; if there is too much, the seed rots. This
condition M. DeCandolle admits also to be good.

V. A fifth condition necessary to germination is the access
of atmospheric air. Seeds will not germinate if placed in a
vacuum. Ray introduced some lettuce-seeds into the receiver
of an air-pump, which he then exhausted; but the seeds did
not germinate. Yet they germinated upon the readmission of
the air, which is proved by consequence to be necessary to
their germination. Whether the whole of the ingredients of
the atmospheric air are necessary, or only part of them, we
do not at present inquire; but we are willing, with M. De
Candolle, to limit the part necessary to oxygen.

Such are the five conditions which I enumerated as indis-
pensable to the success of the process of germination; and
I still persist in maintaining the correctness of the enumera-
tion, notwithstanding all that M.DeCandolle has written
about the germinating of immature seeds, or the non-necessity
of the exclusion of light. By demolishing the two first of the
above conditions M. DeCandolle leaves only three behind.
But what would M. DeCandolle say if I were to come forward
with an objection professing to demolish one of the three con-
ditions which he has suifered to remain? The presence of
water he regards as an essential condition. But I have ac-
tually known acorns to germinate, by protruding a radicle
several inches in length, though lying in the corner of a dry
granary where no water had access to them at all. Such an
objection, undoubtedly, would be but frivolous and vexatious,
—a light in which some might be apt to regard the objec-
tions which have been taken notice of above. For to say
that the maturity of the seed and the exclusion of light are
not necessary conditions of germination seems to be counter
to the opinions whether of the practical cultivator, or of the
speculative phytologist. What says Evelyn on the subject of
the maturity of the seed; and of the exclusion of light ?—
“Choose your seed of that which is perfectly mature, pon-
derous, and sound.” (Sylva, chap. i. sect. 2.) ‘* Keep your
newly sown seeds continually fresh, and in the shade, as much
as may be, till they peep.” (Sylva, chap. xxxii. sect. 2.) Now
this is quite in keeping with the physiological doctrines of the

Action of Ammonia on Chlorides and Oxides of Mercury. 495

present day, founded on facts that pneumatic chemistry, as ap-
plied to germination, has clearly demonstrated. ‘ It is well
known that seeds will not germinate in the light. This is
caused by light decomposing the carbonic acid gas, expelling
the oxygen, and fixing the carbon, whence all the parts be-
come hardened,—a condition under which vegetation cannot
proceed.”—Lindley’s Introd. to Bot. p. 270.

Still we regard the author of the criticism with feelings of
the most unfeigned respect. But when it comes to be circu-
lated at second-hand, and advanced by the plagiarists as an
original remark of their own, without any intimation what-
ever of the source from which it came, we can only regard them
with feelings of contempt. In a late botanico-veterinario-
agricultural periodical, the criticism was excerpted from the
work of M. DeCandolle, and published, in translation, as the
actual critique of the editor or writer of the article, without
the slightest reference to the original from which it was stolen.
But as the periodical in question did not long survive the
commission of this piece of plagiarism, and died a natural
death (some say a violent death) at a very early age, we have
nothing further to say on the subject. De mortuis nil nisi
bonum.

Charing, Kent, Feb. 17, 1836. Patrick KeiTH.

LXXXV. Experiments on the Action of Ammonia on the Chlo-
rides and Oxides of Mercury, and on the Composition of
White Precipitate. By Ropert Kane, M.D., M.RI.A*

The paper of part of which the following is an abstract was
read to the Royal Irish Academy at the October and November
meetings of 1835, and will appear in the next part of the Trans-
actions of that body. By permission of the Council the present
abstract is sent for publication in the Philosophical Magazine.

Y the action of ammonia on a solution of corrosive subli-

mate there is produced a White Precipitate, which has been
frequently made the subject of examination by chemists.
Nevertheless there prevails considerable doubt as to its real
nature. In these countries there has been adopted a theory,
founded principally on the experiments of Hennell, that it
consists of an atom of red oxide of mercury united to one of
sal ammoniac: several, other chemists, however, of equal emi-
nence, as Soubeiran, Guibourt and George Mitscherlich, have
each formed separate and discordant views. I trust it will be

* Communicated by the Author.

496 Dr. Kane’s Experiments on the Action of Ammonia

found that the results now brought forward will clear up these
discrepancies and enable us to attain to a knowledge of its
real nature.

In order to place in evidence the necessity that there exists
for a reexamination of this subject, I shali arrange in a tabu-
lar form the results hitherto obtained. ‘The first column con-
tains the names of the chemists by whom the analyses of white
precipitate have been made, the others the quantities of the
constituents which were actually determined: one element,
oxygen, which is only ascertained from the loss, has been
omitted.

Authors. Mercury. | Chlorine. | Ammonia. | Where described.
Fourcroy ...| 74°] 13:2 6:03 Gmelin, Handbuch.
Hennell ...... 74-24 13:14 6°31 Quarterly Journal *.
Mitscherlich 76°37 13°82 71 Poggendorff, B. 85.
Guibourt .... 78°31 1eys2)! 4:45 Thenard, Traité.
Soubeiran.... 82-1 78 aes Jour. Phar., vol. xii.

To unravel the sources of error that had evidently led
astray so many distinguished chemists was the object of my
experiments.

By the theory of Hennell, generally adopted here, corrosive
sublimate should give almost precisely its own weight of white
precipitate ; thus,

(2 Cl+ Hg) +2 N H? gives . {Hg +(Cl N H*)+ CINH!?:

and 273°6 of sublimate gives 272°34 of white precipitate.
The first set of experiments was made to ascertain how far
that was consistent with the truth.

A. A solution of corrosive sublimate was decomposed by
caustic ammonia, and the precipitate, carefully washed with
cold water, was dried until preserving its pure white colour
it ceased to lose weight. ‘The liquor and washings were then
acidulated with nitric acid and precipitated by nitrate of silver.
The chloride of silver produced gave the quantity of chlorine
abstracted from the sublimate. Of six experiments carefully
conducted the mean was, from 100 of sublimate, 93-1 of white
precipitate, and 13-0 of chlorine in the liquor.

But 100 grains of sublimate contain

Mercury... = 74°09
Chlorine... = 25°91;
we have therefore in white precipitate,

* An account of Mr. Hennell’s experiments on this substance will also
be found in Phil. Mag., First Series, vol. Ixv. p. 226.—Eb1t.

on the Chlorides and Oxides of Mercury. 497

In 93:1 grs. In 100 grs.
Mercury = 74°09 Mercury = 79°57
Chlorine = 12°91 Chlorine = 13°87

B. When white precipitate is heated, there is obtained,
besides gaseous matter and watery vapour, all the mercury
and chlorine united as calomel. This mode was now em-
ployed. A quantity of white precipitate, generally from 15 to
25 grains, was introduced into a very small tube retort, and
heated cautiously until all the ammonia constituent had been
expelled, along with whatever trace of watery vapour ap-
peared, and the calomel completely sublimed white, which
by a little care can be accomplished without any loss. Four
experiments conducted in this way gave results very closely
agreeing, of which the mean is,

From 100 of white precipitate, 92-98 of calomel, containing

Mercury... = 79°14
Chlorine... = 13°84.

C. The mercury was obtained in the metallic state by dis-
solving white precipitate in muriatic acid and decomposing
by protochloride of tin. ‘The mean result was 77°7 of mer-
cury from 100 of white precipitate.

D. White precipitate was dissolved in muriatic acid and
the liquor decomposed by a current of sulphuretted hydro-
gen. The sulphuret of mercury was collected on weighed
filters, dried until it ceased to lose weight, and its quan-
tity determined. ‘The liquor was evaporated and the quan-
tity of residual sal ammoniac ascertained. In this way the
mercury and ammonia are both determined, and the mean re-
sult is, in 100 of white precipitate,

Mercury ... = 77:96
Ammonia... = 7°16.

E. To obtain another value for the ammonia the following
processes were used in addition. When white precipitate is
boiled with a solution of sulphuret of barium, the mercury is
all converted into sulphuret, there are formed chloride and
oxide of barium, and ammonia is disengaged. The gaseous
ammonia was passed over into a vessel of dilute muriatic acid,
and the sal ammoniac obtained dry by evaporation. Ifa so-
lution of iodide of potassium be digested on white precipi-
tate, the quicksilver is converted into biniodide; and there
being formed chloride and oxide of potassium, ammonia is
set free, and its quantity determined as above. The mean of
the results is that 100 of white precipitate contain 6°53 of
ammonia.

I’. In all theories of the composition of white precipitate
Third Series. Vol. 8 No. 49. June 1836. Re OF

498 Dr. Kane’s Experiments on White Precipitate.

hitherto advanced, oxygen is enumerated as a constituent toa
very considerable amount, generally so much as to peroxidize
the whole of the quicksilver. ‘The results hitherto obtained
in my experiments would not appear to leave room .for so
much oxygen, and I therefore endeavoured to obtain an esti-
mate of the amount by direct experiment, on the following
principle. When white precipitate is heated, there is obtained
ammonia and azote, water and calomel, but no free oxygen.
Therefore all the oxygen of the substance has been formed
into water at the expense of the ammonia, and by collecting
the water and determining its weight, the quantity of oxygen
present could be ascertained. A small retort was blown of
strong glass and a capacity of from 0-2 to 0°3 of a cubic inch;
the neck being about two inches long. ‘To this was tightly
connected a small tube containing fused potash, and commu-
nicating by a small tube with the mercurial trough. The re-
tort was carefully weighed and the white precipitate intro-
duced, then weighed again. ‘The desiccating tube was care-
fully weighed, and the apparatus having been connected
tightly, heat was applied until the chlorine and mercury had
all sublimed as calomel. ‘The water was driven over com-
pletely into the potash tube, and the mixed azote and ammo-
nia collected over mercury and analysed by water; the cor-
rections for temperature and pressure, air of apparatus, and
residual gas having been attentively applied. After the opera-
tion the retort was weighed. The residue was calomel, the
loss water and gases. The desiccating tube was weighed ;
the increase of weight was water. ‘There were obtained in
four experiments the following quantities of water:

Material. Water. Water per cent.

22:21 0:22 0-990
20°47 0:14 0°684
12°14 0:08 0°658
19:42 0-00 0-000

Giving a mean of 0°583 per cent, of water.
Summing up all the means we obtain a final result for the
composition of white precipitate, viz.

Mercury: )....¢=-ns00.. = ,,78°60
Chlorine ........00.. = 13°85
ATMO Aresacsvcs sss ees ONC
WY difeiastasaricettdaces c= Opos
DL O08 wenvarsscmneles cde =) OECD

100:00

Dr. Kane’s Experiments on White Precipitate. 499

The ordinary view of white precipitate founded on the ex-
periments of Fourcroy and Hennell give the following numeri-

cal results. Hg+ClNH!

He —— OD ee —— acne
ee ib On wa Wits
ClH = 3642 = 13°37
NEG i), 19515) =, 629

The fallacy of this view is completely proved by the great
variation of the quantity of mercury and the absence of oxy-
gen. Its language has been nevertheless adopted by George
Mitscherlich, and hasthus caused great confusion. He gives the
name Chlorwasserstoffsiure to the hypothetic dry [anhydrous]

muriatic acid, and his formula (N H?+M)+ Hg is so con-
structed. This is shown by the numbers for muriatic acid and
ammonia, 10°7 and 7°1, which he says form sal ammoniac. In
order to get his value for the chlorine in the table of results
(p. 496), I added to his muriatic acid half the oxygen which
he gives to the oxide of quicksilver. In fact his analysis cor-
rectly interpreted overturns the very hypothesis it was in-
tended to support, for he obtained
Mercury ... = 76°37
Muriatic acid...10°70 af veg?
Ouyiew sWats..i efit Chlorine ,... =. 13:82
Ammonia... = 7:10

97-29
Leaving a vacancy of only 2°71 for all the oxygen to oxidize
the whole of the quicksilver.

The simplest view to take of the existence of the chlorine
in this substance, is to suppose it united with half the mer-
cury into corrosive sublimate. It is almost the only view which
agrees with its reactions. ‘Then in what state is the remainder
of the mercury? We may suppose it peroxidized, and the oxide
united with the ammonia, giving the formula (2 Cl + Hg)

+ (H+2N H?) and the following numerical results.

2Hg = 405°60 or, per cent. 77°00
Cr = Trae 13°45
20x = 16°00 —__ i 3°04
2NH* = °34°30 6°51.

This agrees closely with Mitscherlich, and also with some
of my own analyses. It differs nevertheless from the mean
of my results in the quantities of mercury and chlorine, and
particularly in the amount of oxygen; this hypothesis sup-
posing the presence of 3°04 pee cent. of oxygen,—a body the

Siu Z

500 Mr. Tovey’s Researches in the

existence of which as a constituent I could not determine at
all, and which the quantities of the other constituents would
appear absolutely to exclude. It is therefore necessary to ex-
amine whether any other method of arrangement is more sa-
tisfactory.

From the researches on oxamide, benzamide, &c. it follows,
that by the action of ammonia on an oxide there may be
formed water and a compound of the body N H? with the
base of the oxide. If we consider this to have taken place in
white precipitate, we should have the formula

(2 Cl+ Hg) +(2 N H’+Heg), giving

2Hg = 405°60 or, per cent. 79°73

2 Cl = 70°84° 13°93

Q9NH? = 32°30 6°34;
and this compound should yield on analysis, on being decom-
posed, 6°73 per cent. of ammonia.

The question whether ammonia in acting on metallic oxides
forms water and metallic amides is one of the most interest-
ing now requiring to be examined; but notwithstanding the
bearing the results just described have on the question, I do
not wish to adopt too positively the opinion that white preci-
pitate is a compound of deutochloride and deutamide of
mercury until more extended researches shall enable me to
argue from a greater number of facts derived from the reac-
tions with other metals.

LXXXVI. Researches in the Undulatory Theory of Light,
in continuation of former Papers. By Joun Tovey, Esq.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

i NOW proceed, as I proposed at the conclusion of my last
paper, p. 272, to integrate the equations

dé cid? ey eds

d@ dx iPr d x
dy, Lier a d*y,

i fae + Ss; “Aaa + &c. (1.)

+ &c.

oh dle
de oN dx? + $y dat + &e.

As € is, by supposition, a function of x and 4, we can put

Undulatory Theory of Light,—continued. 501

& =psinke + p'sinkax + p’ sin kle + &e.

+ qgcoskx + q' coskx + gq" cos k"x + &e.
where Ps P's p", &es q 75 7", &e. are functions of t, and hk, k!, k",
&c. arbitrary constants. (Poisson, Traité de Mécanique,

No. 514.) Now, if we substitute p sin kx + q cos k x for = in
the first of the equations (1.), it becomes

a
{art (@#-SH +8) p | sinks

et eR seis ie ka = 0;
rr: ( -) 7p coska = 0;

and, this equation being true for all values of x, resolves itself
into
dp 212 2
oT tae (s ke —s” fA &c. ) p=0,
dT . (ej2 gh
apt (s i? —s! i++ &e. ) iO.

The complete integrals of these equations are p = A sin né
+Beosni, g = A'sinnét + B' cosné¢; where A, B, A’, BY,
are arbitrary constants, and x = 4/ (s? 4°—s!? k*.4+ &e.). Hence
the complete integral of the first of the equations (1.) can be
expressed by the sum of a series of functions, each of which
is of the form
(A sin x¢+B cos n#) sinkx+ (A’sinnt+ BI cos nt) coskx.

This expression is, by the rules of trigonometry, equiva-
lent to

A+B! A'—B
2 2

cos (zt—kax) + sin (nt—k x)

A-—B )

d A
a ae Bie (mt+hk ax) + E svenepe 2)

which, if we put

A+B! s A'—B : ’
: = asin a, —Z— = @ Cos a, = — Bsind,
'4+B
ee = pcos 0,

may, by the same rules, be reduced to
asin (nt—ka +a) + Bsin(nt + ke + 0).

It follows, therefore, that since the second and third of the
equations (1.) are of the same form as the first, and since »
and % are, like 1, functions of 2 and ¢, we can express the
complete integrals of these equations by putting

id

502 Mr. Tovey’s Lesearches in the
& = d.asin (nt—kxv+a)+.Bsin (nt+ha+0),
y = X.a, sin (x,t—k, x+a,)+=.B6 sin(nt+k r+6), (2.)
¢ = 2.a,sin (nv, f—hk,v+a,)+=.6,sin (n,t+h,a+5,);

where
WS PAS I eH eT Se.)
n = WV (spk?P — Pk} + &c.), (3.)
my = V (shy sky + &e.):
the sums = being extended to all the requisite values of the
arbitrary constants.

We perceive, by the equations (2.), that the motion of the
system may be regarded as compounded of a number of co-
existing movements, severally expressed by the terms of the
sums =. And when we confine our attention to a single term
of the first sum in one of these equations, which we may do
in a great variety of problems, we have virtually the same ex-
pression for the displacement of a molecule of an undulating
medium, as is assumed tacitly by Sir Isaac Newton, and ex-
pressly by Professor Airy*.

Taking separately the displacement y, and considering only
one term of the first sum in the expression for this quantity,
we have

; 7 = a, sin (n,t —k,x + a).

It is well known that this equation represents a series of
equal and continuous waves, the length of each wave being

25 g : 5 :
pre where 27 is the circumference of a circle whose radius
ic

éf ~ .
is unity. Now, if we increase x uniformly, so as to make

k hnctaie : a dz. 1,
mt—k,« constant, remains constant, and > = ee

Hence we perceive that these waves travel, in the direction of
2 positive, with a velocity equal to aps If »= 8, sin(n é
+k,x+ b,), which is a term of the second sum, the move-
ment is similar, except that the waves travel in the contrary

direction.
The second of the equations (3.) gives

is s/? 5
%; = 5,4 (1- aera + &c.) 3

an equation affording the same theory of dispersion as that
which has been so satisfactorily investigated and verified by

* See Airy’s Mathemat. Tracts, p. 259.

Undulatory Theory of Light,—continued. 503

Professor Powell in the recent Numbers of your Journal.
This I have shown more explicitly in your Number for Ja-
nuary last, p. 7.

Since, by the last equation, the velocity of the waves, and
consequently the refraction of the light at the surface of the
medium, depends chiefly upon s,, while the dispersion depends

fo
s/@ : :
upon =a i? and the following terms of the series, we see that

the dispersion may be different for different media, though
the mean refraction be the same; contrary to the opinion
which so long retarded the improvement of refracting tele-
scopes.

The equations (3.) may, perhaps, lead to a theory of ab-
sorption as well as of dispersion; since it is obvious that they
may become impossible for particular values of 4 It should
be observed that the sums s”, 5,°, s,°, s!°, &c. are not necessarily
positive, and I now think it would be better to denote them
by s, s,5 Sj s';&c. I adopted the other notation in order
to assimilate the formula to those employed in the theory of
sound.

In the case of undulation which we have been considering,
the waves are plane waves, perpendicular to the axis of 2 ; we
now pass on to the consideration of converging and diverging
waves.

Let us take the case of a system of waves going and re-
turning to and from a certain point; calling this point the
centre of agitation. ‘Then the diameter of the sphere of in-
fluence of any molecule being an insensible quantity, it is evi-
dent that the minute portion of one of the waves contained
within the sphere cannot, at any sensible distance from the
centre of agitation, differ sensibly from the same portion of
a plane wave. ‘Therefore, as the motion of any molecule is
affected only by the molecules within the sphere of its in-
fluence, it follows that the equations (3.), which give the ve-
2 " au of plane waves, will also give, at any

| 7]
point of the system, the velocities with which diverging or
converging waves are transmitted in the direction perpendi-
cular to the wave-surface at that point.

When the molecules are so arranged that the sums s°, 5°,
$75 &c. are the same for all directions of the rectangular co-
ordinates, the velocities of the waves are the same for every
radius drawn from the centre of agitation; and consequently
the wave-surfaces are spherical.

bia n
locities 7

504 Mr. Tovey’s Researches in the

If we conceive a slowly tapering cone (fig. 1.) to have its

Fig. 1. B E
A A sill eae aee pe eebveed
C D

summit A at the centre of agitation of a system of spherical
waves, and if we take the axis of the cone for the axis of 2,
it is clear that the displacements £, 4, % of the molecules
within the frustum B C D E may be regarded as functions of
x and ¢; and may therefore be expressed by the equations
(2.), nearly. It is also manifest that the same equations will
express the displacements for any other frustum of the me-
dium, by making the arbitrary quantities to vary according to
the position of the frustum. Consequently, if we suppose

= asin(nt—kx+a)
for the frustum B C D E, the same equation may be taken to
express the value of & for any other frustum of the same cone,
by regarding a, 2, k, a as functions of x.
Let g be the radius of the sphere of influence of the mole-

cules: then, if = were infinitely small, the minute portion of

a wave contained within the sphere would be a plane wave,
and a, 2, k,a constant. Hence we perceive that these quan-

tities must be functions of a and consequently, that we may

write
2
ee Ay B £+4c(4) + &e.,
x x
niles, Ata +0 (2) + &c.,
x x
g

x
2
gee Am 4 BM 2 4 Om/ g ) aoa

x
the only variable quantity in these series being z.
Now when z is infinite « must be zero; therefore A = 0:

and as 8. is, at all sensible distances from the centre of agi-

Undulatory Theory of Light. 505
tation, an extremely small quantity, we may reject its powers
above the first; therefore « = BS . The quantities x, k, a

approach, as x increases, towards the values which they have
in the case of plane waves, which values are independent of a.
And since the small portion of a wave contained within the
sphere of influence of any molecule cannot, at any sensible
distance from the centre of agitation, differ sensibly from the
same portion of a plane wave, we may regard 7, k, a as con-
stant for all parts of the cone. If then we retain @ to denote

B
Bg, the constant part of —*, we have

oi “ sin (nt — kw + a):

and, in general, for any cone taken as we have supposed, we
have, from the equations (2.),

es (sinnt+hk a+b),

f=. = sin (nt—ka+a)+ =.

a . C
i sh ra sin (n,t—hk,x+a,)+ = . Pi sin (n,t+k,x+b,), (4.)

s sin (2, f+h,c+0,).

When the waves all move from the centre of agitation, the
second sums in the equations (4.) will vanish: and limiting
our view to a single term of one of the first sums, we have an
expression for the displacement virtually the same as that
which Professor Airy, in his valuable tract on the Undulatory
Theory of Optics, has partly assumed and partly borrowed
from the theory of sound*.

It may be observed, by the way, that the method adopted
in this paper of expressing the displacement of the molecules,
is analogous to that employed so successfully in physical astro-
nomy to express the differences between the mean and true
places of the planets.

When the molecules are so arranged that the sums s’, s/’,
s,2, &c. are different for different directions of the coordinates,
waves going and returning to and from a centre of agitation
will not be spherical. The most simple case of such waves
will probably furnish a subject for another paper.

I am, Gentlemen, yours, &c.
Evesham, April 15, 1836. Joun Tovey.

P.S. I perceive that throughout my last paper I inadver-
tently called the differences Aw, Ay, Az variations.

* Mathemat. Tracts, p. 271.
Third Series. Vol. 8. No. 49. June 1836. 3F

pee irks
= ea sin (2,t—k,«+,) + -

Rw ROS wal

LXXXVII. On the former Extent of the Persian Gulf, and
on the Non-identity of Babylon and Babel; in Reply to Mr.
Carter. By C. T. Bexe, Esq., £.S.A.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
(THE opinion which was, in the first instance, advanced by

me in the Number of your Journal for February 1824*,
was to the effect that the low lands of the Euphrates and Ti-
gris have been formed by the gradual deposits of those rivers,
and that this operation has been so extensive, that, at the time
of the erection of the Babel of Genesis, it must have been phy-
sically impossible for that city to be built near the spot where
the Babylon of Nebuchadnezzar afterwards stood. ‘This
opinion may be considered as embracing two distinct and
separate propositions :—the first is that, within the period of
history, an advance of the Jand upon the sea has taken place
of sufficient importance to affect materially the geography of
the localities in question; the second is that, within the same
period, that advance has been so great as (independently of
all other arguments,) to warrant my conclusion with respect
to the non-identity of Babylon and Babel. If the former of
these propositions be untrue, @ fortior? must the latter be so;
but, on the other hand, even if the former be established, it
does not follow that the latter is likewise correct.

From Mr. Carter’s former arguments I certainly was led to
consider, that he not merely disputed the correctness of the
first proposition to its entire extent, but that he went yet
further, and contended that the changes (if any) which have
taken place, are altogether insignificant. In his present re-
marks he says, however f, ‘I much object to such expressions
in the reply as, ‘ Mr. Carter has, in fact, asserted the opinion
that, since the time of Nearchus, the encroachments on the
gulf must be very unimportant,’ omitting the words ‘to the
point in question, any later encroachments,’ &c., as conveying
the idea of a mere assertion without proof, and a much broader
one than my remarks warrant.” I am most anxious that no
difference should exist between us on the score of mere mis-
conception of each other’s meaning, and [I therefore give at
length, in the note at foot, an extract of the whole passage
from which I made my citation{; and I put it to the candour

* Lond. and Edinb. Phil. Mag., vol. iv. p. 108—111.

+ Supra, vol. vii. p. 195,

t ‘Following the course of Nearchus, as given in his own clear account
of the voyage preserved by Arrian, from his arrival at the Arosis, the river

Mr. Beke on the former Extent of the Persian Gulf. 507

of my opponent himself, whether I was not fairly authorized
in the conclusion which I came to with respect to his mean-
ing: indeed I would ask whether, when in his present reply
he says, with respect to “the navigation of Alexander and his
fleet in the delta streams,” that ‘the ancient canal, the entire
circuit, all the points of the navigation then presented by the
spot, are still offered for our observation,” it must not be un-
derstood as his unqualified opinion that “since the time of
Nearchus the encroachments on the gulf have been very un-
important.” If I am’so unfortunate as still to misunderstand
his meaning, I beg to assure him that I do so most uninten-
tionally.

As regards the observation that my words ‘convey the idea
of a mere assertion without proof,” Mr. Carter must allow me
to say, that a construction appears to be put upon them which
ought not by any means to be adopted in a discussion like
the present. Every proposition advanced, or assertion made,
on either side, must be presumed to be made upon what are
regarded as ‘‘proofs;” and it is simply from the considered
insufficiency of those alleged proofs that the correctness of
any such proposition or assertion is questioned on the other
side. For my part, I feel that I might have reason to object,
not merely to some expressions, but also to the tone generally
in which Mr. Carter’s last reply is written; but I refrain from
doing so, and I sincerely trust that neither of us will have
occasion again to refer to any such unpleasant topic.

In order to prevent any future misconception, it is to be
understood that the first and principal point in dispute be-
tween us is, whether a change of such importance has taken
place as materially to affect the geography of the localities in

at the N.E. next before coming to the streams of the Delta, in his progress
to Kataderbis and the island of Margastana, in his passage through the
channel over the shoals to his arrival at Diridotis (by the Khore Abdallah),
on the S.W. side of the Delta, and comparing it with the present state of
the country, we learn with surprise the small degree of change which the
general characters of the coast have undergone during the lapse of so many
ages. Dr. Vincent, in his able work on the Commerce and Navigation of
the Ancients in the Indian Ocean, adverting to this remarkable fact, ob-
serves, that Capt. Howe’s chart ‘ explains the journal of Nearchus as per-
fectly as if it had been composed bya person on board of his fleet,’ (vol. i.
p- 423.) and (p. 466.) ‘the pilot on board Nearchus’s ship steered exactly
the same course’ (along the coast of the Delta) ‘as MacCluer’s Karack pilot
2000 years afterwards.’ The junction of the river called by Arrian the
Eulzus (coming from the N. or N.E.) with the Tigris by the still existing
ancient Hoffar canal, across which Alexander sent a part of his fleet while
he sailed down the Eulzus to the mouths of the Tigris, and so round to
meet it (Arrian, Exp. Alex. vii. 7.) further shows that to the point in
question any later encroachments on the gulf must be very unimportant.”
Lond, and Kdinb, Phil. Mag., vol. v. P 247—8, The Italics are Mr. Carter’s.
S8F2

508 Mr. Beke on the former Extent of the Persian Gulf,

question; that is to say, a change so great as to render the
descriptions of ancient writers inapplicable to the actual coast-
line and state of the neighbourhood generally.

Seeing that my hypothesis precludes the possibility of Ne-
archus’s voyage being made applicable to the present coast of
Susiana and the countries at the head of the Persian Gulf, it
is scarcely necessary for me expressly to dispute in detail the
correctness of the identifications, considered to have been
established by Dr. Vincent, of the river Arosis, of Kataderbis,
the island of Margastana, Diridotis, &c. &c.* That the river
Karoon is not the Eulzeus, nor Shuster the representative of
Susa, has already been asserted by many geographers of emi-
nence, whose voices are united in favour of Shus and the river
Haweeza or Kerrah. Without intending to range myself with
these geographers, I believe I am correct in saying that, as
between them and Dr. Vincent, the greater show of reason is

* Although I am quite willing to concede that “a few miles of addition
to the Delta is not the question” between us, yet, as regards the learned
Dean’s identifications, I must remark, that a few miles—nay, a very few
miles indeed—of addition would (I much suspect,) render it impossible that
“Capt. Howe’s chart should explain the journal of Nearchus as perfectly
as if it had been composed by a person on board of his fleet.” To establish
the correctness of this position, it appears to be necessary, not merely that
the coast should have remained unvaried since the time of the Greek navi-
gator, but that Capt. Howe’s chart should accurately represent that coast: it
ought, consequently, to correspond in all points with the trigonometrical
survey recently made by Lieuts. Brucks and Haines, of the East India Com-
pany’s Marine Service.

By the kindness of Capt. Horsburgh I have been furnished with copies
of the Company’s chart, as also of that of Lieut. MacCluer (by Dalrymple,
1786 and 1788): Capt. Howe’s he was not in possession of. Owing to the
longitude not being marked in MacCluer’s, J am prevented from making an
exact comparison of these two charts; still differences of sufficient moment
are to be detected between them. For instance, the island of Karack is
represented by MacCluer as being 8, and Korgo more than 4 geographical
miles long, whereas they are actually just half those lengths respectively :
Buna (Derabuna), by the Core Moosah, is made as much as 9 miles long,
from north to south, and 3 miles broad, whilst it is only 3 miles long, and
less than 1 mile broad, its length being from east to west: Derah, adjoin-
ing this Jast island, is made 7 miles long and 3 miles broad, but it is in fact
only a mile and a half each way: the Core Abdallah, represented in the
copy of 1786 as being 10 miles broad, with 8 miles of coast between it and
the mouth of the Bussorah river, and in that of 1788 as only 6 miles broad,
with about 10 miles of coast, is actually 12 miles broad, and the two mouths
meet at a point, without any coast intervening. These variations (which
are only a portion of what might be pointed out,) may be said to be but
trifles with respect to “the general characters of the coast ;” still they are
more than sufficient to show that MacCluer’s chart would have been rather
a dangerous guide for Nearchus to have placed implicit confidence in.
Capt. Howe’s chart, which was adopted by Dr. Vincent, is (I believe) not
even so correct as that of MacCluer; but I have not at present the means
of referring to the Dean’s work, so as to ascertain this positively.

and on the Non-identity of Babylon and Babel. 509

on their side. Under their hypothesis, however, Charax,
which was situate at the confluence of the Tigris and Eulzeus,
will have to be placed not 37 but about 100 miles up the
river; so that “the plain fact” by which ‘even the increase
of 35 miles” in the distance of that city from the sea is “an-
nihilated” in so summary a manner, is not quite so manifest.
The position of Charax remains, I conceive, yet to be deter-
mined; but, let it have been where it may, I confess I do not
exactly understand how my “extravagant hypothesis” is to be
‘at once disposed of,” for the reason that, “if the distance of
Charax, the port, had increased but 70 miles” (or it may be
only 35 miles,) between the times of Alexander and Pliny (400
years), “‘the whole distance to Babylon could have increased
but 70” (or 35) miles in the 2160 years which have elapsed
since the voyage of Nearchus down to the present time. Leav-
ing the ‘extravagant hypothesis” quite out of the question, it
appears to me that, assuming the same rate of increase through-
out the whole period, the gain would be about 380 (or 190)
miles.

The “‘diversitas auctorum” of which Pliny complains, is a
point upon which Mr. Carter makes a great stand; and hence
he comes to the strange conclusion, that the distance between
Babylon and Charax was “utterly uncertain.” Now it may
be perfectly comprehensible that the naturalist should have
been in difficulty upon the subject, and unable to arrive at
any satisfactory result, on account of the apparent discrepan-
cies among the various authorities which were before him ; yet
it will not, I presume, be thence argued, that either Babylon
or Charax was so situate as not to have been perfectly easy of
access, so that the distance between them might always have
been ascertainable, in the same way as it would be in the
present day (and perhaps with less difficulty,) were both cities
in existence. There is not the slightest reason, therefore, for
imagining that “the distance was utterly uncertain.” The
various authors must be presumed to have made their several
statements upon good grounds, and with a competent know-
ledge of the actual distance; and whatever discrepancies may
be found among them, beyond those which will always exist
where distances are only estimated and not actually measured,
are mainly, if not entirely, to be attributed to differences in
the standards of measurement employed by them respectively.
And this, in fact, is what Pliny himself says: ‘Inconstantiam
mensurae” (the measure itself and not the distance measured,)
*‘diversitas auctorum facit: cum Perse quoque schceenos et pa-
rasangas, alii alia mensura determinent*.” 'This difficulty be-

* Hist. Nat., lib. vi. cap. 27.

510 Mr. Beke on the former Extent of the Persian Gulf,

comes no slight one when, as was frequently the case, those
standards of measurement, although of widely different
lengths, had the same name*; added to which, we must bear
in mind that the various distances recorded were, at various
times, applicable to different states of the country, in those
portions of it which were liable to change. The possible ex-
istence of errors of copyists is, of course, not to be lost sight
of; but I question much whether we may be authorized to en-
tertain “serious doubts of the authenticity” of passages which
do not exactly coincide with our preconceived notions.

In his former papert Mr. Carter cites various authorities
in illustration of the passage from Pliny, in part originally
quoted by met; which passage he understands (though I can-
not conceive how,) to mean that “long before Pliny’s time
the two rivers had united above the embouchure somewhere,
not by encroachments on the gulf and formation of delta,
but simply by the labour of hands;’ and in his present reply
that gentleman repeats that those various authorities “ all
harmonize with the unbroken sense of this passage :” meaning,
of course, as it is interpreted by him. I confess that in my
last answer I dismissed these authorities rather summarily,
and I did so on account of my not being able to discover their
application, and on account also of the “discrepancies” exist-
ing among them, which my opponent himself admitted §. And
on this point an explanation is due from me to Mr. Carter. In
your Number for June last (1835), I stated that “these autho-
rities, according to his (Mr. C.’s) admission, contain ‘some dis-
crepancies,’ and are not always ‘very explicable,’” in which I
was thus far wrong: the being not “‘ very explicable” was (as
he now observes,) * distinctly ‘applied by him ¢o Pliny’s general
account of the two rivers only,” the “discrepancies” having

* We have a precisely analogous case in the various miles of the present
day, and we may easily conceive the case of a geographer in future ages
being strangely perplexed on this account. Take, for instance, the distance
between St. Petersburg and Riga, which by a Swede would be said to be
50 miles ; by a German, 71 miles; and by an Englishman, 285 or 330 miles;
whilst a Frenchman would call it 95 or 118 leagues, and a Russian 495
wersts; to which might be added, perhaps, twenty other measures of modern
Europe (principally miles), all differing with one another. Here would be
ample ground for complaining, as Pliny did, of the “inconstantia mensure,”
but certainly none for the conclusion that ‘‘the distance was utterly un-
certain.”

+ Lond. and Edinb. Phil. Mag., vol. v. p. 249.

{ “Inter duorum amnium ostia 25 mill. pass. fuere, aut (ut alii tradunt)
7 mill. utroque navigabili. Sed longo tempore Euphratem preclusere Or-
cheni, et accolz agros rigantes; nec nisi Pasitigri defertur in mare.” — Hist.
Nat., lib. vi. cap. 27.

§ “ But notwithstanding some discrepancies, the conclusion from the
above authorities surely is,” &c. .

and on the Non-identity of Babylon and Babel. 511

been intended by him (as will be seen from the last note,) to
apply merely to the rest of the authorities cited by him. Iam
most happy to be able thus to correct my error.

As regards these various ‘‘ harmonizing,” “ discrepant ”
authorities, I even now refrain from considering them in de-
tail; for it would only needlessly be taking up much room,
since my remarks would be little more than the continued
repetition, with respect to each of them individually, of the
assertion which I make respecting them collectively; namely,
that Iam unable to see their applicability, either to Pliny’s
statement as above explained by Mr. Carter, or to the present
condition of the country. It will not be denied that the gene-
ral conclusion from them is, that the two rivers in question
“have, at a very early period, united inland somewhere ;” but
I cannot conceive by what possible means the further con-
clusion is to be arrived at from them, that ** Khorna was the
grand confluence in all ages*;” for the two rivers may, by
the union of their deltas, have formed a junction at some point
much further inland, and yet, for ages afterwards, have still
continued their (in part) separate courses to the sea.

Among the many writers thus cited by Mr. Carter, is the
geographer Ptolemy, to whom, however, whilst he quotes the
particular passages from the other authors which he considers
applicable, he refers only in general terms. Yet Ptolemy’s
description of these rivers, and the countries through which
they flow, is that, perhaps, which is the most important of the
whole, and which, consequently, requires to be more particu-
larly considered. ‘The purport of this description appears to
be as follows: That to the north of Babylon the Euphrates
divided itself into two streams, whereof the one flowed south-
ward by that city, and the other eastward past Seleucia: that
between these two branches of the Euphrates there was a river
called the Basilius, which, on the one hand, fell into the Ti-
gris below Apamea, and, on the other hand, joined the main
stream of the Euphrates flowing past Babylon, at some di-
stance below that city: that the Euphrates likewise threw off
an arm called the Baarsares; and that both this arm and also
the main stream itself, continued their courses southward, and
divided themselves into several subordinate branches, with
which they formed lakes and marshes towards the head of the
Persian Gulft.

The Alexandrian philosopher’s account must, of course, be

* How does such a conclusion tally with the notion that the Orcheni
“united” the two rivers “ simply by the labour of hands”? Did they make
the junction at Khorna?

t+ ‘H rov EvQecrov Séois, nab yy oxiCerat sis re trav dice Babuaraavos

512 Mr. Beke on the former Extent of the Persian Gulf,

taken with all the imperfections in geographical knowledge
belonging to his age; but the whole context affords a mani-
fest indication that, so late as about his time, (the beginning
of the second century of our zera,) the Euphrates possessed its
separate delta, of which the apex was above Babylon, and of
which the western branches formed lakes and marshes below
that city; whilst (although the junction is not mentioned,) the
most eastern branch, as it passed by Seleucia, must have joined
the Tigris. The outlet of the lakes and marshes into the sea
is also not described; in fact, as Pliny tells us, it was already
closed up by the Orcheni: but the authorities cited by Mr.
Carter, as also Herodotus to whom I shall presently refer,
plainly show that, at an earlier period, the delta streams of the
Euphrates had their separate union with the Persian Gulf.
In my last paper* I attempted to show how these lakes and
marshes at the mouths of the Euphrates would, in the first
instance, have been produced, and how, subsequently, the
branches of the river which formed them would successively
have been stopped and filled up by the operation of natural
means, the western branches being those which were first
closed. The Orcheni would have finished the work of nature
by stopping up the eastern arm, which, till then, discharged
itself into the sea, not more than 25 or 27 miles (as stated by
Pliny,) from the western mouth of the Tigris; and the lakes
and marshes of the Euphrates, having no longer a channel
through them, would then gradually have become silted up,
in the manner I have further suggested in the same paper.
Much light would be thrown upon the subject if, by local
examination, it were determined (which it might be without
much difficulty,) how far westward the course of any branch of
the Euphrates has once extended +.

piovra, ab tov Oi Dercunsins, Gv 6 msteey xarsivas Basiasiog rorepoc,
Ob Sols THe EXTLOTNS LLOLLLS sereeeeseoerene veeee 00 AE x. —Lib. v. cap. 18.
"ACEI acececncercctnccnnccnseronsccessonesen abs KOS.
iD qv 4 tov Baoirsiov rorapmov reds tov Tier ovpeSoay, yy Ae Kage.
—Ibid.

Arcepétovar 02 rAv xaouv OTe Basirsios worms, nal 6 bie tHe BaGvadvos
fav, xal 6 xaerovuevos Beccegoccens: os Tw wiv EvQeary ovpearrss, xara Seow
ZOE OVTLY (OT rrerscseceeceeesees snadahttogech aces a6 XO So’.

Ta 0: die Baluarwvias, os xarsizas 0 Buoirsioc rorepos CUVEE TOV.

of =O a’.

Tlosotor té of roramol obrol, nal wi ax witav exteoral Aluvas nal Edn,

Sv vod evry cov ered sabres LT ccceeersere in s’ XB s’.—Lib.v. cap. 20.
Edit. Basil. 1533.

* Lond. and Edinb. Phil. Mag., vol. vii. p. 45.

+ The most eastern branch of the Euphrates, which joined the Tigris
above Babylon, would appear also to have become closed, unless indeed it

and on the Non-identity of Babylon and Babel. 513

At the present moment (as I have before remarked,) I do
not consider that our present knowledge of the countries in
question is sufficient to enable us to come to any entirely
satisfactory conclusion, or to reconcile the various apparently
conflicting statements of antiquity, which evidently cannot be
made to apply (under favour of Mr. Carter must it be said,)
to the present state of the country, and which it will require
much labour and not less caution to adapt to any hypothetical
condition of the country. But one point, which is not suffi-
ciently attended to by commentators generally, cannot be too
strongly borne in mind by those who may apply themselves to
the task. It is, that where a fact is expressly asserted by a
writer of character, who possessed the means of knowing it,
its correctness must be admitted, until something positive be al-
leged sufficient to invalidate it. Mr. Carter appears entirely
to neglect this rule, when he cites Arrian as “saying ex-
pressly, the Euphrates has a higher channel than the Tigris,
which receives the waters of the Euphrates by many streams,”
and yet, without hesitation, stigmatizes this an “error.” Per-
fectly true it may be, as Col. Chesney reports, that, in the
present day, “the Tigris gives a large contribution to the
sister stream by the canal of the Hie, about 220 miles above
the gulf;” but may it not be equally true, that formerly the
two rivers united much higher up, at a point at which their
relative levels were as Arrian so expressly states them to have
been? The mere circumstance that the river Al Huali or
Hermas, which at the present day runs in a direction towards
the west so as to unite with the Khabour, is considered to
have had in former times an eastward course and to have
joined the Tigris*, is in entire accordance with such a state of
things.

Mr. Carter says, “* Xenophon understood this better [than
Arrian]: he mentions four canals by which the latter [the Ti-
gris] pours its waters into the Euphrates +.” Did Xenophon
really say this, I should be compelled to admit his testimony,
as that of a man of unquestioned honour and integrity and an
eye-witness, even in spite of the express assertion of Arrian to
the contrary ; but it is far from being the case, and Mr, Carter
has evidently been misled from consulting merely some loose

was kept open by artificial means, in which case it would, in the result, have
been regarded merely as a canal.

* See Rennell’s Illustrations of the Retreat of the Ten Thousand, p. 102;
see also Orig. Bibl., p. 113, where the opinion is expressed that “at the time
when the extent northward of the Persian Gulf was much greater than it is
at present...... the river Al Huali had its separate course to the sea.”

+ Anab,, lib. i. cap. 7.

Third Series. Vol. 8. No.49. June 1836. 3G

514 Mr. Beke on the former Extent of the Persian Gulf.

and inaccurate version. A reference to the original would
have shown him that what the author really says respecting
these four canals is simply cicGaAdovor 02 cig tov Edgperny:
correctly rendered in the Oxford version (edit. 1676), ‘Iidem
in Euphratem znfluunt,” and by Spelman “ they fall into the
Euphrates.” Smaller streams are commonly said to fall into
larger ones with which they communicate, so that these words
do not necessarily convey any idea beyond that of mere union;
and the writer being near the Euphrates (see the next para-
graph of the text,) would naturally describe these canals as
tributaries to that river, even had the actual run of the waters
been in the other direction. Seeing, however, that these ca-
nals were navigable, and that they were of course made without
locks, it is manifest that no great difference of level between
the two rivers could have existed ; and whichever way it may
have been, most assuredly there was not, in a country which to
this day is almost a dead flat, any opportunity for the one river
to ‘pour its waters into” the other.

Mr. Rich tells us in his Memoir on the Ruins of Babylon
(2nd edit. p. 18), that during the inundation of the Euphrates
“rafts laden with lime are brought almost every day from
Felugiah to within a few hundred yards of the northern gate
of Bagdad.” This must (I have reason to believe) be under-
stood as referring to a canal existing there, which joins the
two rivers, and which is filled during the flooded season; but
even here, no less than 380 (600—220) miles above the Hie,
by which (as Col. Chesney informs us, ) the Euphrates receives
the waters of the Tigris, the levels of the two rivers so closely
correspond as to allow of a navigable communication ex-
isting between them! Mr. Carter has discoursed very learn-
edly respecting the mode in which rivers produce their deltas,
but there appears to be a fundamental defect in his reasoning:
he takes as a “fact” that the Tigris ‘can be more rapid (than
the Euphrates] only through flowing from a higher country
down a greater slope.” But if we look to what is actually the
fact, we find that at two distinct points, namely, at Felugiah
(opposite Bagdad) and at Khorna, the Tigris and Euphrates are
of equal (or nearly equal) heights. Between these two points,
however, we have the unquestionable evidence of Col. Chesney
that the two rivers are “very different in every respect,” the
former moving in a rapid and the latter in a dull and lingering
stream. This difference in character is clearly not produced
by the Tigris ‘flowing from a higher country down a greater
slope,” since at Bagdad that river is no higher than the Eu-
phrates at Felugiah. Other causes have therefore to be sought
for, among which may be noticed the greater length of the

Prof. Young on the Theory of Vanishing Fractions. 515

Euphrates between these two points and the breadth of its
bed in the lower portion of its course, both which causes must
produce a corresponding diminution in its speed, and on the
other hand the contraction of the channel of the Tigris, which
must be attended with a corresponding acceleration of the mo-
tion of its waters.

Col. Chesney is referred to as describing the Euphrates as
in the present day flowing in a dull and lingering stream:
Herodotus, also an eye-witness, in his description of Babylon
talks of the “deep and rapid streams of the great Euphrates *.”
No one will for a moment doubt the accuracy of Col. Chesney’s
observation; but is not credit also due to Herodotus? and is
he, in like manner as Arrian, to be “unceremoniously thrown
overboard,” whilst the facts respecting the former condition of
these rivers remain unascertained? In the passage last cited,
the Halicarnassian traveller further expressly asserts that the
Euphrates “discharges itseif into the Persian Gulf;” which
assertion he confirms in his more detailed statement that that
river, “ which before flowed in an almost straight line,” had
its course so turned by Nitocris, that in his time, “those who
wished ¢o go from the sea up to Babylon were compelled to touch
at Ardericca three times on three different days+.” Surely such
unqualified and unequivocal assertions of plain matters cf fact
are entitled to consideration, and are not to be put aside as
errors simply because they are not applicable to the present
state of things, or rather, perhaps, because they do not coin-
cide with what we have been taught by former commentators
to receive as the truth.

[To be continued. ]

LXXXVIII. On the Theory of Vanishing Fractions. By
J. R. Youne, Esg., Professor of Mathematics in Belfast
College.

N a letter inserted in the April number of this Journal (p. 295)
I ventured to offer some objections to certain novel positions,

lately advanced by an ingenious mathematician, in an Essay
on the Fundamental Principles of the Differential and Inte-
gral Calculus. To these objections the author of the Essay

as furnished a reply, in the number for May (p. 393); and I
am happy to find, from the general tone of it, that Mr. Wool-
house has considered my scruples with the same good feeling
in which they were avowedly offered.

* Ea wiyas, nal Babds, nal raxds, eSler d€ odtos és Thy “Epudeqv Sarno-
cav.—Clio, 180.

+ Clio, 185, t Communicated by the Author,

s8G2

516 Prof. Young on the Theory of Vanishing Fractions.

In my former communication, I contented myself with sim-
ply pointing out the fallacy involved in the extremely general
statements which I extracted from the Essay referred to; and
with tracing the source of this fallacy to the circumstance of
the author having unguardedly assumed the converse of a cer-
tain proposition, to be equally general with the proposition
itself, which converse holds however only in particular cases.

The direct proposition to which I here allude is this, viz.
that when in certain hypotheses any of the analytical conditions
of a problem disappear, the final result, to which the general
process leads, takes the form 2. The converse proposition is,

that when the final result takes the form © original conditions

must have disappeared. ‘This latter is the affirmation distinctly
conveyed, without the slightest qualification, in the propositions
marked II. and III. in Mr. Woolhouse’s reply; and it will be
remembered, that against those propositions only my objec-
tions were directed; for.I cheerfully admitted that much of
Mr. Woolhouse’s Essay was ‘in strict accordance with the
usual notions of this doctrine.”

To show that these objections were valid, I adduced an in-
stance (that of a geometrical series) in which the propositions
objected to would lead to error; and in adverting to this in-
stance, in his reply, it will be seen that my respected friend
has not defended the positions in question from the charge of
making the sum of the said geometrical series anything, but
has shown that another position (Prop. IV.), a position which
was never impugned, is competent to supply the correct result.
Surely my ingenious friend does not consider it to be a suffi-
cient defence of Proposition III. to prove that its affirmations
are neutralized by Proposition IV.; and yet there is no other at-
tempt made to establish its truth. The proposition which Mr.
Woolhouse discusses at page 395, does not at all contribute to
this object; for that is the converse of the one which it behoves
him to prove, in order to establish his third principle: this
principle requires the proposition stated above, in Italics, and
not the one which Mr. Woolhouse has demonstrated in the
preceding Number. There is no dispute as to the form of the
result when conditions vanish; the question is, does this form
necessarily imply vanishing conditions in the original analytical
statement of the problem? Mr. Woolhouse’s third principle
unequivocally states z# does. But innumerable examples to
the contrary may be adduced. The well-known problem of
Clairaut, which has for its object the determination of the spot
between two lights, which is equally illuminated by both, is a
case in point, and furnishes a satisfactory refutation of the

Prof. Young on the Theory of Vanishing Fractions. 517

principle in question, as may be seen by a reference to the
Algebra of Lacroix, where the circumstances of the problem
are discussed at Jength. The ordinary expression for the ra-
dius of curvature of a plane curve, will also furnish other ex-
amples of the fallacy of the assumed principle; for when, in
any particular example, that expression takes the form of a

fraction, as r = ray we have, by differentiating,

pean ee
and it is well known that whatever values of x and y render
this expression equal to zero, the same values, provided they
fulfill the original condition, or equation of the curve, will be-
long to points in it of maximum or minimum curvature ; or
to points at which the contact with the osculating circle is
above the second order. Now it is plain that the conditions

P= 0, Q=O eressecscccceee’ (2)

will cause a value of (1) to be zero; if, therefore, these con-
ditions furnish for x and y values which satisfy the equation
of the curve, the points to which they refer will be distin-
guished from the other points by the order of contact being
higher there than elsewhere. Instead of deducing this con-
clusion from the expression r = 9? We Ought, in accordance
with Mr. Woolhouse’s third principle, to say that at every
such point the radii of curvature are innumerable, which is
obviously absurd. As an example, let us take the common
parabola, of which the equation is y? = 4m 2. By the usual
process we obtain for 7 the expression

_ fm+e = ALS
8 x "4m? Q”’

and the conditions (2) are, in this case,

Liege ab

(m +a)%y= 0, Amat = 0,

which are satisfied by the values x = 0, y = 0; and these
values, fulfilling the original condition y? = 4m x, it follows
that the origin of the axes, that is the vertex of the parabola,
is a point at which the contact is above the second order, and
this we know to be the case from other considerations,

It is unnecessary to multiply examples illustrative of the
fallacy of this third principle “as a general rule,” and indeed
a passage in the reply of my Menta friend leads me to sus-
pect that, while writing that reply, he himself had some mis-

518 Prof. Young on the Theory of Vanishing Fractions.

givings about it. The passage I refer to is at page 396, where
Mr. Woolhouse, in his reasonings on the form °, limits his
arguments to those comparatively few cases in which the re-
sults of that form are obtained in such a way, “that no mul-
tiplication or division by a power of x — a occurs in the pro-
cess.” If only results obtained under such restrictions as
these are admitted to come under the second and third prin-
ciples, then the generality of those principles is of course at
once given up, and my friend and J are thus far agreed. But
then so limited a principle of interpretation falls greatly short
of a general theory; and moreover requires, inits application, an
acquaintance with the texture of the entire process too minute
to be generally attainable; it requires, in fact, that we know
the composition of every multiplier and divisor employed,—an
impossible problem beyond certain limits.

At page 399, Mr. Woolhouse enters into a digression upon
‘the general theory of analytical results,” respecting which
he considers me to be in error, because in my last letter I had
said that the fact of the ellipse question, admitting multiple
solutions, was information which the analytical result was quite
incompetent to supply; and he observes, “I never before
heard of the incompetency of an analytical result to afford any
positive information that an investigation could admit of.” In
this gratuitous admission of paucity of information upon sub-
jects in which he so eminently excels, my friend has done him-
self a wanton injustice. He is too profoundly acquainted with
all the subtleties of the Integral Calculus, and its applications,
not to have “heard of” singular solutions, which, though not
comprised in the resulting integrals which furnish the general
solutions to certain differential equations, have, nevertheless,
the property of satisfying the proposed conditions. But a
more comprehensive view of the results of even common alge-
bra, would, I think, have induced my friend to withhold the
remark just quoted. Mr. Woolhouse ascertains the number
of admissible solutions from “the nature of the problem.”
By taking a more enlarged view, it would have occurred to
him that the result might furnish solutions, not only contrary
to the express stipulations of the problem, but at variance
with even the original analytical conditions, although these
may have a much wider range. The results after these “ so-
lutions étrangéres” are rejected from them, are those from
among which are to be selected the solutions to the problem.
In the present discussion it is the connexion between the ana-
lytical conditions and the analytical results, which is the mat-
ter before us; and it is, I suspect, from not keeping this in
mind, that Mr. Woolhouse has been led to say, in mistake,

Prof. Young on the Theory of Vanishing Fractions. 519

that “ Professor Young involves himself in a palpable incon-
sistency when he arrives at the fact of the ellipse question
admitting multiple solutions, by an examination of the origi-
nal analytical conditions, and at the same time alleges that the
analytical result is quite incompetent to supply that informa-
tion.” The mathematical readers of this Journal will however
readily perceive, that what is here,charged as “ palpable in-
consistency” is in perfect accordance with the strictest analy-
tical accuracy ; and that the “inconsistency” would have been,
in inferring the multiple solutions from the analytical result,
without reference to the original conditions, as Mr. Woolhouse
has done, thus assuming (what is not true) that the converse
of a certain proposition holds merely because the proposition
itself is known to be true. Mr. Horner in the present volume
of this Journal (p. 43.) has brought forward whole cluster
of instances, in each of which, as he clearly shows, “ the ana-
lytical result is quite incompetent to supply the information”
even as to whether the question admits of a single solution,
much less as to whether it admits of multiple solutions: the
information sought must be obtained in all these cases, as I
have obtained it in the ellipse question, viz. by a direct appeal
to “ the original analytical conditions.” Without such an ap-
peal how are we to know whether the analytical result to which
the condition
Qa4+Vx2?7—T=5
leads, viz.
32°— 202+ 32=0,

will supply values competent to satisfy that condition? The
presumption is that it w2// supply such values; upon trial how-
ever we find them to fail: and yet these values will satisfy the
immediately antecedent equation, but this is not sufficient ;
every anterior step must be satisfied, up to the original equa-
tion inclusively ; and the error committed in overlooking this
would be precisely similar to that which Mr. Woolhouse ap-
pears to me tohave committed, in inferring the multiple solutions
to the ellipse question, merely because these solutions satisfy
the final result*. ‘The same mistaken view of the “theory of

* It is but justice to Mr. Woolhouse to state, however, that he admits
(p. 399) that “ the nature of the problem, as originally presented, is the pro-
per source of rejective information,” although he maintains that the original
analytical conditions do not furnish the proper source of information, as to
whether, in certain hypotheses, one of those conditions becomes destroyed,
or two or more of them become dependent ; but, on the contrary, that the

Oo. , side a .
result 5 8 asufficient indication that one or other of these circumstances

must take place. (See III. p. 394.) Ihave endeavoured to show, however,
that this result is not competent to furnish any information on the subject.

520 Prof. Young on the Theory of Vanishing Fractions.

analytical results” accompanies his animadversions at page
398-9 in the last number of this Journal; he appears to think
it sufficient that the antecedent equation should be satisfied, for
he remarks, ‘* The corresponding antecedent equation to the
result z = 2, when cleared of fractions, is 07 = 0, or 0 = 0,

an equation that is obviously satisfied without any limitation
to the value of z, and that cannot fail therefore to be compa-
tible with the other equations or conditions.” The statement,
in connexion with this remark, viz. that “‘® can never be the

symbol of absurdity,” has a little surprised me, because the
contrary is a fact so generally known to analysts. To occupy
these pages by examples of this would be quite superfluous, as
they abound in most of the Continental books on algebra. In
the comprehensive work of Bourdon there is an ample supply of
such examples, and from which he deduces the ordinary conclu-
sion, viz. that “le symbol © est tantot un caractére d’indéter-
mination, tantot un caractére d’absurdité.”

From what has now been said of the symbol 2, it appears
that, when it is not the indication of absurdity, or of incompati-
ble conditions, it may arise from either of these two causes: viz.

i ‘ Sie Je 1°
from taking the ultimate, or limiting, value of =, the general

result of an analytical process; or, without regard to this ex-
treme limit, it may arise from the destruction of one or more
of the conditional equations. One or other of these circum-
stances must take place in connexion with the occurrence of
5 whenever this symbol is at all interpretable. I say when-

ever the symbol is znterpretable, for cases may arise in which
this symbol is indicative of neither multiple solutions, nor of li-
miting values, nor of incompatible conditions. In such cases
therefore other modes of solution must be sought. ‘The in-
stances to which I now allude are among those in which the
vanishing of the numerator is not necessarily accompanied by
the vanishing of the denominator ; but where each vanishes in-
dependently, in virtue of distinct hypotheses introduced among
the arbitrary quantities in each. With the exception of these
unintelligible results, the occurrence of © is always traceable to
one or other of the circumstances before mentioned; which
circumstances, although having no necessary connexion, may
nevertheless, as in the case of the ellipse question, both exist
simultaneously.

When therefore 5 takes the place of =, in any hypothesis,

Be
ii P
we may be assured that the limiting values of Q will always

.

Mr. Faraday on the Condensation of the Gases, &c. 521

subsist with the original analytical conditions, however they
may be modified under the proposed hypothesis; but we can
neither deny, nor affirm, that other values may also subsist
with these conditions; for ‘this is information which the ana-
lytical result is quite incompetent to supply,” and which must
be derived solely from ascertaining the effect of the proposed
hypothesis upon the original analytical restrictions; and that
this is a fair and legitimate deduction from the foregoing ex-
amination, I think no person who enters into it with unbiassed
judgement, will be disposed to deny.
Belfast, May 7th, 1836.

LXXXIX. On the History of the Condensation of the Gases,
in reply to Dr. Davy, introduced by some Remarks on that
of Electro-magnetic Rotation. By Micuart Farapay,
Esq., D.C.L. F.RS., §c., in a Letter to Richard Phillips,
Esq., F.RS. L.& E., &c. :

My pear Sir, Royal Institution, May 10, 1836.

| HAVE just concluded looking over Dr. Davy’s Life of his

brother Sir Humphry Davy. In it, between pages 160
and 164 of the second volume, the author links together some
account, with observations, of the discovery of electro-magnetic
rotation, and that of the condensation of the gases, concluding
at page 164 with these words: “I am surprised that Mr. Fa-
raday has not come forward to do him [Sir Humphry Davy]
justice. As I view the matter, it appears hardly less necessary
to his own honest fame than his acknowledgement to Dr.

Wollaston, on the subject of the first idea of the rotary mag-

netic motion.”

I regret that Dr. Davy by saying this has made that neces-
sary which I did not before think so; but I feel that I cannot
after his observation indulge my earnest desire to be silent on
the matter without incurring the risk of being charged with
something cpposed to an honest character. ‘This I dare not
risk ; but in answering for myself, I trust it will be understood
that I have been driven unwillingly into utterance.

Dr. Davy speaks of electro-magnetic rotation, and so also
must I, for the purpose of showing certain coincidences in
dates, &c. between the latter part of that affair and the con-
densation of chlorine and the gases, &c. Oersted’s experi-
ments were publised in Thomson’s Annals of Philosophy for
October 1820, and from this, I believe, was derived the first
knowledge of them which we had in this country. At all
events it was the first intimation Sir Humphry Davy and I had
of them, for he brought down the Number into the laboratory
on the morning of its appearance (October Ist) and we re-

522 Mr. Faraday on the Condensation of the Gases, Sc.

peated the experiments together. I may remark that this is
aproof that Dr. Davy, in the Life* as well as elsewhere+, does
not always understand the meaning of his brother’s words,
and I think that he would never have written the lines which
have driven me to the present and a former replyt if he had.

Immediately upon Oersted’s great discovery, the subject was
pursued earnestly, and various papers were written, amongst
which is one by Sir Humphry Davy, Phil. Trans. 1821,
page 7, read before the Royal Society Nov. 16, 1820, in which,
at page 17, he describes the rolling of certain wires upon knife-
edges, being attracted when the north pole of the magnet was
presented under certain conditions of current, and repelled
under certain other conditions of current, &c.

Another paper was a brief statement by the Editor of the
Quarterly Journal of Science, (Mr. Brande,) in which he an-
nounces distinctly and clearly Dr. Wollaston’s view of the na-
ture of the electro-magnetic force, and its circumferential cha-
racter. It is in the tenth volume, p. $363, and may be dated
according to the number of the Journal, Ist January 1821.

Then there are my historical sketches in the Annals of
Philosophy, N.S., vols. ii. and iii. written in July, August, and
September 1821, and the paper describing my discovery of
the electro-magnetic rotation dated 11th September 18218,
and others; but we will pass on to that of Sir Humphry Davy,
read 6th March 1823)|, which with its consequents is synchro-
nous with the affair of the condensation of gases. ‘This is
the paper which Dr. Davy says “he (Sir H. D.,) concludes
by an act of justice to Dr. Wollaston, pointing out how the
discovery of the rotations of the electro-magnetic wire round
its axis by the approach of a magnet, realized by the inge-
nuity of Mr. Faraday had been anticipated, and even at-
tempted by Dr. Wollaston in the laboratory of the Royal
Institution {”.

I have elsewhere** done full justice to Dr. Wollaston on the
point of electro-magnetic rotation, and have no desire to lessen
the force of anything I have said, but would rather exalt
it. But as Dr. Davy has connected it with the condensation
of the gases, I must show the continual tendency to error
which has occurred in both these matters. Dr. Davy, then, is
in error when he says I realized Dr. Wollaston’s expectation ;
nor does Sir Humphry Davy say what his brother imputes to
him. I did not realize the rotations of the electro-magnetic wire

* Vol.ii.p.143. + Lond. and Edinb. Phil. Mag., 1835, vol. vii. p. 340.
t Ibid. p. 337. § Quarterly Journal of Science, vol. xii. p. 74.

|| Phil. Trans. 1823, p. 153. q Life, vol. ii, p. 160.

** Quarterly Journal, vol. xv. p. 288.

Mr. Faraday on the Condensation of the Gases, Sc. 523

round its axis; that fact was discovered by M. Ampére, at a
later date; and even after I had discovered the rotation of the
wire round the magnet as a centre, and that of the magnet
round the wire, I could not succeed in causing the wire to
revolve on its own axis*. ‘The result which Wollaston very
philosophically and beautifully deduced from his principles,
and which he tried to obtain in the laboratory, was, that
wires could be caused to roll, not by attraction and repulsion
as had been effected by Davy+t, but by a tangential action, ac-
cording to the principles which had been already made known
to the public as his (Dr. W.’s) by Mr. Brandet.

What Sir Humphry Davy says in his printed paper § is this:
«¢ T cannot with propriety conclude without mentioning a cir-
cumstance in the history of the progress of electro-magnetism
which, though well known to many Fellows of this Society, has,
I believe, never been made public, namely, that we owe to
the sagacity of Dr. Wollaston the first idea of the possibility
of the rotations of the electro-magnetic wire round its axis by
the approach of a magnet; and I witnessed early in 1821 an
unsuccessful experiment which he made to produce the effect
in the laboratory of the Royal Institution.” This paper being
read on the 6th of March 1823, was reported on the first of the
following month in the Annals of Philosophy, N.S., vol. v.
p- 304; the reporter giving altogether a different sense to
what is conveyed by Sir Humphry Davy’s printed paper, and
saying that “ had not an experiment on the subject made by
Dr. W. in the laboratory of the Royal Institution, and wit-
nessed by Sir Humphry failed, merely through an accident
which happened to the apparatus, he would have been the dis-
coverer of that phenomenon ||.”

I have an impression that this report of the paper was first
made known tome by Sir Humphry Davy himself, but afriend’s
recollection makes me doubtful on this point: however, Sir
Humphry, when first he adverted to the subject, told me it
was inaccurate and very unjust; and advised me to draw up
a contradiction which the Editor should insert the next month.
I drew up a short note, and submitting it to Sir Humphry
he altered it and made it what it appears in the May Number
of the Annals of Philosophy, N.S. vol. v. page 391, as from the
Editor, all the parts from “but writing only” to the end being
Sir Humphry’s; and I have the manuscript in his hand-writing
inserted as an illustration into my copy of Paris’s Life of Davy.

* Quart. Journ. of Science, vol. xii. p. 79. + Phil. Trans. 1821, p.17.

{ Quart. Journ., vol. x. p. 363. § Phil. Trans. 1823, p. 158.

|| In justice to the reporter, I have sought carefully at the Rapal Sdciety’s
for the original manuscript, being the paper which he heard read ; but it
cannot be found in its place.

524 Mr. Faraday on the Condensation of the Gases, $c.

The whole paragraph stands thus: ‘ *,.* We endeavoured
last month to give a full report of the important paper commu-
nicated by the President to the Royal Society on the 5th [6th]
of March*; but writing only from memory, we have made two
errors, one with respect to the rotation of the mercury not
being stopped, but produced, by the approximation of the mag-
net; the other in the historical paragraph in the conclusion,
which, as we have stated it, is unjust to Mr. Faraday, and does
not at all convey the sense of the author. We wish, therefore,
to refer our readers forward to the original paper, when it shall
be published, for the correction of these mistakes.—Zdzt.”

From this collection of dates and documents any one may
judge that I at all events was wyustly subject to some degree
of annoyance, and they will be the more alive to this if they
recollect that all these things were happening at the very time
of the occurrence of the condensation of gases and its con-
sequences, and during the time that my name was before the
Royal Society as a candidate for its fellowship. Ido not
believe that any one was wittingly the cause of this state of
things, but all seemed confusion, and generally to my disad-
vantage. For instance, this very paper of Sir Humphry Davy’s
which contains the “ act of justice,” as Dr. Davy calls it, is en-
titled, “On a new phenomenon of Electro-magnetism.” Yet
what is electro-magnetic was not new, but merely another form
of my rotation; and the mew phenomenon is purely electrical,
being the same as that previously discovered by M. Ampere.
As M. Ampére’s result is described for the first time in a
paper of the date of the 4th of September 1822+, and Sir
Humphry Davy’s paper was read as soon after as the 6th of
March 18234, the latter probably did not know of the result
which the former had obtained.

To conclude this matter: in consequence of these and other
circumstances, and the simultaneous ones respecting the con-
densation of chlorine, I wrote the historical statement, to
which Dr. Davy refers ||, in which, admitting everything that
Dr. Wollaston had done, I claim and prove my right to the
discovery of the rotations I had previously described. This
paper before its publication I read with Dr. Wollaston; he
examined the proofs which I have adduced at p. 291, and
after he had made a few alterations which brought it into the
state in which it is printed, expressed his satisfaction at the ar-
guments and his approval of the whole. The copy I have pre-
served, and I will now insert the most considerable and im-

* So far is mine; the rest is Sir Humphry Davy’s.

+ Ann. de Chim., 1822, vol. xxi. p. 47. t Phil. Trans. 1823, p. 153.
§ Quarterly Journal of Science, vol. xv. p. 288.

|| Life, vol. ii. p. 146. bottom of the page.

Mr. Faraday on the Condensation of the Gases, $c. 525

portant of Dr. Wollaston’s corrections as an illustration. At
the end of the paragraph at the bottom of page 291, I had
expressed the sense thus: ‘¢ But what I thought to be attraction
and repulsion in August 1821, Dr. Wollaston long before per-
ceived to be an impulsion in one direction only, and upon that
knowledge founded his expectations.” This he altered to: * But
what I thought to be attraction zo and repulsion from the wire
in August 1821, Dr. Wollaston long before perceived to arise
from a power not directed to or from the wire, but acting circum-
Serentially round it as axis, and upon that knowledge founded
his expectation.” The parts in Italics are in his hand-writing.

With respect to the condensation of the gases, I have long
ago done justice to those to whom it was really due, and now
approach the subject again with considerable reluctance; for
though I feel that there is some appearance of confusion, still
I regret that Dr. Davy did not leave the matter as it stood.
All my papers on the subject in the Transactions of the Royal
Society had passed through the hands of Sir Humphry Davy,
who had corrected them as he thought fit, and had presented
them to that body. Again, all the facts that Dr. Paris has
stated upon his own knowledge* are correct; he made that
statement as his own voluntary act and without any previous
communication with me, so that I think I might have been left
in that silence which I so much desired.

The facts of the case, as far as I know them, are these: In the
spring of 1823, Mr. Brande was Professor of Chemistry, Sir
Humphry Davy Honorary Professor of Chemistry, and I
Chemical Assistant, in the Royal Institution. Having to give
personal attendance on both the morning and afternoon che-
mical lectures, my time was very fully occupied. Whenever
any circumstance relieved me in part from the duties of my
situation, I used to select a subject of research, and try my
skill upon it. Chlorine was with me a favourite object, and
having before succeeded in discovering new compounds of
that element with carbon, I had considered that body more
deeply, and resolved to resume its consideration at the first
opportunity: accordingly, the absence of Sir Humphry Davy
from town having relieved me from a part of the laboratory
duty, I took advantage of the leisure and the cold weather and
worked upon frozen chlorine, obtaining the results which are
published in my paper in the Quarterly Journal of Science
for the 1st of April 18234. On Sir Humphry Davy’s return
to town, which I think must have been about the end of

* Paris’s Life of Davy, pp. 390, 391, 392. t Vol. xv. p.71.

526 Mr. Faraday on the Condensation of the Gases, &c.

February or the beginning of March, he inquired what I had
been doing, and I communicated the results to him as far as
I had proceeded, and said I intended to publish them in the
Quarterly Journal of Science. It was then that he suggested
to me the heating of the crystals in a closed tube, and [ pro-
ceeded to make the experiment which Dr. Paris witnessed, and
has from his own knowledge described*. I did not at that
time know what to anticipate, for Sir Humphry Davy had not
told me his expectations, and I had not reasoned so deeply as
he appears to have done. Perhaps he left me unacquainted
with them to try my ability. How I should have proceeded
with the chlorine crystals without the suggestion I cannot
now say, but with the hint of heating the crystals in a close tube
ended for the time Sir Humphry Davy’s instructions to me,
and I puzzled out for myself in the manner Dr. Paris describes,
that the oil I had obtained was condensed chlorine. This is
all very evident from the paper read to the Royal Society,
though it may seem at first to stand opposed to the notes and
papers that Sir Humphry Davy communicated in conjunction
with and after mine. When my paper was written it was, ac-
cording to a custom consequent upon our relative positions,
submitted to Sir Humphry Davy, (as were all my papers for
the Philosophical Transactions up to a much later period,)
and he altered it as he thought fit. This practice was one of
great kindness to me, for various grammatical mistakes and
awkward expressions were from time to time thus removed
which might else have remained.

The passage at the commencement of the paper which I
shall now quote was of Sir Humphry Davy’s writing, and in
fact contains everything that, and perhaps rather more than,
he had said to me: ‘* The President of the Royal Society
having honoured me by looking at these conclusions, sug-
gested, that an exposure of the substance to heat under pres-
sure, would probably lead to interesting results; the following
experiments were commenced at his request}.” I say “rather
more,” because I believe pressure was not recurred to in our
previous verbal communication. However, I proceeded to
make the experiment, and was making it when Dr. Paris
came into the laboratory as he has described, and my thoughts
at that moment are embodied and expressed in my paper
in the following words: “I at first thought that muriatie
acid and euchlorine had been formed; then that two new
hydrates of chlorine had been produced; but at last I sus~

* Paris’s Life, p. 391. ;

3 t om Trans, 1823, p. 160.,[or Phil. Mag., First Series, vol. xii, p. 413.—
DIT.

Mr. Faraday on the Condensation of the Gases, Sc. 527

pected that the chlorine had been entirely separated from
the water by the heat, and condensed into a dry fluid by the
mere pressure of its own abundant vapour*.” I then de-
scribe an experiment entirely of my own, in which I proceed
to verify this conjecture, and go on to say, “ presuming that
I had now a right to consider the yellow fluid as pure chlo-
rine in the liquid state, I proceeded to examine its properties,
&c. &c.+”

To this paper Sir Humphry Davy added a notet, in which
he says, “In desiring Mr. Faraday to expose the hydrate of
chlorine to heat in a closed glass tube§, it occurred to me that
one of three things would happen; that it would become fluid
as a hydrate; or that a decomposition of water would occur,
and euchlorine and muriatic acid be formed; or that the chlo-
rine would separate in a condensed state.” And thenhe makes
the subject his own by condensing muriatic acid, and states
that he had “‘requested” me, (of course as Chemical Assistant, )
“to pursue these experiments, and to extend them to all the
gases which are of considerable density, or to any extent so-
luble in water;” &c. This I did, and when he favoured me
by requesting that I would write a paper on the results, I began
it by stating “that Sir Humphry Davy did me the honour
to request 1 would continue the experiments, which I have
done under his general direction, and the following are some
of the results already obtained:||” and this paper being im-
mediately followed by one on the application of these liquids
as mechanical agents, by Sir Humphry Davy 4, he says in it,
‘* One of the principal objects that I had in view in causing ex-
periments to be made on the condensation of different gaseous
bodies, by generating them under pressure, &c.”

1 certainly took up the subject of chlorine with the view of
pursuing it as I could find spare time, and at the moments
which remained to me after attending to the directions of my
superiors. It however passed in the manner described into
the hands of Sir Humphry Davy, and a comparison of the
dates will readily show that I at least had no time of my own
to pursue it. My original paper was published on the first
of April 1823, that being the first number of the Quarterly
Journal which could appear after the experiments had been
made: but in the short time between the first experiment and
the publication much that I have referred to had occurred, for

* Phil. Trans. 1823, p. 162. + Ibid. p. 163. t Lbid., p. 164.
§ Observe, not “ to pm under pressure.” See my remarks in the pre-
eeding page.
Phil, Trans, 1823, p.189. [or Phil. Mag., First Series, vol. Ixii, p. 417.
—Enir. } q] Ibid. p. 199.

528 Mr. Faraday on the Condensation of the Gases, §c.

not only had I communicated my results to Sir Humphry
Davy, and received from him the hint, but my paper on fluid
chlorine had been read (13th of March), and his note also, of
the same date, attached to it; and the Editor of the Quarterly
Journal, Mr. Brande, had time prior to the printing of my
original paper to attach a note to it stating the condensation
of chlorine and muriatic acid, and expressing an expectation
that several other gases would be liquefied by the same means*.
On the 10th of April my paper on the condensation of several
gases into liquids was read, on the 17th of April Sir Humphry
Davy’s on the application of condensed gases as mechanical
agents, and on the Ist of May his Appendix to it on the
changes of volume produced by heat.

I have never remarked upon or denied Sir Humphry Davy’s
right to his share of the condensation of chlorine or the other
gases; on the contrary, | think that I long ago did him full
“ justice” in the papers themselves. How could it be other-
wise? he saw and revised the manuscripts; through his hands
they went to the Royal Society, of which he was President at
the time; and he saw and revised the printer’s proofs. Al-
though he did not tell me of his expectations when he suggested
the heating the crystals in a closed tube, yet I have no doubt
that he had them+; and though, perhaps, I regretted losing
my subject, I was too much indebted to him for much previous
kindness to think of saying that that was mine which he said
was his. But observe (for my sake) that Sir Humphry Davy
nowhere states that he told me what he expected, or contra-
dicts the passages in the first paper of mine which describe
my course of thought, and in which I claim the development
of the actual results.

All this activity in the condensing of gases was simultaneous
with the electro-magnetic affair already referred to, and I had
learned to be cautious upon points. of right and priority.
When therefore [ discovered in the course of the same year
that neither I nor Sir Humphry Davy had the merit of first
condensing the gases, and especially chlorine, I hastened to
perform what I thought right, and had great pleasure in
spontaneously doing justice and honour to those who deserved

* Quarterly Journal, vol. xv. p. 74.

+ I perceive in a letter to Professor Edmund Davy, published by Dr.
Davy in the Life, vol. ii. p. 166, of the date of September 1, 1823, that Sir
Humphry Davy said, “ The experiments on the condensation of the gases
were made under my direction, and I had anticipated, theoretically, all the
results.” It is evident that he considered the subject his own; but I am
glad that here, as elsewhere, he never says that he had informed me of his
expectations. In this Sir Humphry Davy’s negative, and Dr. Paris’s posi-
tive, testimony perfectly agree.

Mr. Charlesworth on the Crag of Suffolk, &c. 529

it*. I therefore published on the 1st of January of the fol-
lowing year (1824) a historical statement respecting the lique-
faction of gases+, the beginning of which is as follows:
“* I was not awareat the time when I Jirst observed the lique-
faction of chlorine gas, nor until very lately, that any of the
class of bodies called gases had been reduced into the fluid
form; but having during the last few weeks sought for in-
stances where such results might have been afforded without
the knowledge of the experimenter, I was surprised to find
several recorded cases. I have thought it right, therefore, to
bring these cases together, and only justice to endeavour to
secure for them a more general attention than they appear as
yet to have gained.” Amongst other cases the liquefaction of
chlorine is clearly described}{. The value of this statement of
mine has since been fully proved; for upon Mr. Northmore’s
complaint ten years after, with some degree of reason, that
great injustice had been done to him in the affair of the con-
densation of gases, and his censure of “the conduct of Sir
H. Davy, Mr. Faraday, and several other philosophers for with-
holding the name of the first discoverer,” I was able by re-
ferring to the statement to convince him and his friend that if
‘my papers had done him wrong, J at least had endeavoured
also to do him right §.

Believing that I have now said enough to preserve my own
“honest fame” from any injury it might have risked from
the mistakes of Dr. Davy, I willingly bring this letter to a
close, and trust that I shall never again have to address you
on the subject.

I am, my dear Sir, yours, &c.

Richard Phillips, Esq., &c. &c. M. Farapay.

a

XC. On the Crag of Suffolk, and on the Fallacies connected
with the Method now usually employed Sor ascertaining the
relative Age of Tertiary Deposits. By Epwarpv Cuar.es-
worn, Esg., F.G.S.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

[X former communications I treated of the crag as a ter-
tiary formation consisting of separate marine deposits, and

* Monge and Clouet had condensed sulphurous acid probably befere the
year 1800. Northmore condensed chlorine in the years 1805 and 1806.

t Quarterly Journal of Science, vol. xvi. p- 229. t Lbid., p. 236.

§ Lond. & Edinb. Phil. Mag. 1834, vol. iv. p- 261,

Third Series. Vol.8. No. 50, Supplement, June 1836. 3 H

530 Mr. Charlesworth on the Crag, and on ascertaining

being desirous that the grounds upon which I have adopted -
this opinion should be fairly placed before those to whom the
geological history of our own island is an object of interest,

I propose in the course of the following observations to enter

more minutely into the merits of that question.

An attempt has been made to explain the relation which
the divisions of the crag bear to each other by assuming that
the lower or coralline beds constitute the only original deposit,
from which the rest of the fossiliferous strata above the Lon-
don clay in Suffolk and the adjoining counties have been de-
rived, by the operation of diluvial agents.

It may perhaps appear hardly necessary to enter upon the
refutation of a theory which is so irreconcilable with recorded
facts, but as it is desirable that no stumbling block should lie
in the way of future investigation, I shall advert to some of
the points which are especially opposed to its reception.

Until the subject was recently brought before the notice of
the Geological Society, our available sources of local infor-
mation respecting the crag and its organic remains were almost
entirely confined to the published observations of Mr. R. C.
Taylor and Mr. Samuel Woodward, the former of whom had
paid great attention to the tertiary deposits of Norfolk and _
Suffolk, and to whose exertions, I believe, we are indebted
for the first list of their characteristic fossils. I might, per-
haps, reasonably inquire how far the diluvial character as-
signed to the red crag is consistent with the results attending
my own personal investigation. For the present, however,
I am anxious that your attention should be drawn to several
passages occurring in the works of the above-named writers,
and which are certainly calculated to throw some light upon
the point at issue if the matter be really one requiring elu-
cidation.

Mr. Taylor’s interesting memoir on the geology of Eastern
Norfolk was published in 1827, but his range of observation
was by no means limited to the particular district which he
there professes to describe. We find, however, no allusion
to the Ramsholt stratum, although he had evidently extended
his researches into the adjoining county and explored the coral
reefs of Aldborough and Orford. A circumstance which ap-
pears to have particularly arrested the attention of Mr. Taylor
during his investigation of the crag was the natural distribution
of its fossil Testacea, the occurrence of which he points out in
that part of the formation which we have lately been informed
“‘is decidedly diluoium or disrupted crag.” At page 15, he
remarks, ‘‘it is characteristic of the shells and other organic
bodies deposited with the crag, that they are by no means dif-

the relative Age of Tertiary Deposits. 5381

fused in equal numbers and proportions throughout, but occur
at intervals in groups and genera. Thus at Cromer the pre-
dominant and remarkable shells are Mactre; at Runton, Car-
dia; nearer Clay, Murex striatus; at Bawdesey cliff, Murex
reversus and Pectunculus; at the Beacon, Venus equalis; at Fe-
lixstow, Pectunculus and Voluta Lamberti; south of Landguard
cottage, Murex contrarius and Mya lata; at Bramerton and
near Norwich are Murex striatus, Telling, and Balani.” There
is no reference here made to Ramsholt, Sudbeurn, or Ald-
borough; all the localities named in the above extract are
those of the red or dilwvial crag.

At page 23, Mr. Taylor observes, “ that after the forma-
tion of the chalk the waters deposited the marine exuviee, and
gave existence during the long period in which they occupied
that portion of its former surface to those remarkable accumu-
lations of crag shells which we now witness.” And again, at page
29: “ A district bordering a hundred miles upon our eastern
coast is occupied by an ancient marine deposit. ...... at one
point exhibiting groups of shell-fish allied to those of the
neighbouring sea, and at another composed of numerous ge-
nera which are neither to be recognised living in any part of
our globe or assimilated to the fossil shells of other forma-
tions.” .

I need not pursue Mr. Taylor’s views any further, but
would refer the reader to his work or to his previous papers
in the Philosophical Magazine. The above quotations fur-
nish ample proof that he had not discovered the diluvial na-
ture of the red crag, although it was that part of the forma-
tion with which he was so intimately acquainted.

In 1833, Mr. Samuel Woodward published an outline of
the Geology of Norfolk, in which we are presented with a
brief notice of the crag, confirming the previous observations
made by Mr. Taylor. At page 19, Mr. W. mentions that “the
crag district is a narrow tract running southward from the
coast between Cromer and Weybourn, and passing’ Norwich
in its progress towards the Suffolk coast, the great deposit of
this formation.” Mr.) Woodward, without suspecting that the
deposit which he is describing is déliviwm, proceeds to re-
mark that “this tract appears to us to have been an estu
in the antediluvian period... .. -Viewing the thick beds of
testaceous remains, we cannot hesitate to admit that the sea
occupied for a long period the part of Norfolk now under con-
sideration.”

Again, at page 21: Another point worthy of attention is
the apparent agreement in the gregarious habits of the original
occupiers of ae shells with the recent Mollusca, confining

83H2

532 Mr. Charlesworth on the Crag, and on ascertaining

them to particular spots or habitats; thus we find that the
beds of crag shells are not continuous but deposited in patches;
and that the shells in the Suffolk beds are in numerous in-
stances generically and in almost all specifically different to
those found near Norwich.” No traces of the coralline cra
have yet been detected in the county of Norfolk; it should
therefore be borne in mind that the above observations refer
solely to the upper deposit.

We are here furnished with the clearest evidence that
Messrs. Woodward and Taylor agree in one important par-
ticular; viz. that the fossils of the red crag are not promis-
cuously jumbled together, but localized very much in the same
manner as the Mollusca inhabiting our present seas: both geo-
logists also infer from the great accumulation of these fossils
that the ocean must for a long time have remained stationary
over that district in which they occur.

In order then to maintain the decisions in reference to this
subject which [appeared in your Number for November, it
will be necessary either to dispute the accuracy of the facts now
adduced, or to show that this gregarious distribution of ge-
nera and species may exist in a formation resulting from those
operations which we designate by the term diluvial. I will-
ingly admit that the views of geologists as to the real na-
ture of these operations are not of the most definite charac-
ter, and at the present time our opinions respecting the true
origin of what are called diluvial deposits are undergoing im-
portant modifications; but allowing the utmost latitude for
any discordance of this kind, I apprehend that it will require
more than ordinary ingenuity to show that the conditions
which prevailed at the time when the formation of the crag
was going forward can in any way be approximated to that
state of things which is generally understood to be the ne-
cessary concomitant of diluvial action.

Those who are at all familiar with the geology of Nor-
folk, cannot fail to have observed that the crag, in common
with other formations, has been subjected to the abrasion of
diluvial currents. Mr. Taylor remarks that * portions pro-
bably from its western edges have been swept away. Their
fragments mingled with those of the chalk and preceding
formations, piled in enormous heaps, form the cliffs of Cro-
mer and Trimmingham, 250 or 300 feet in thickness upon the
original crag which rests in situ at their base.”

I imagine that it would not greatly increase the reputation
of any geological observer to infer the diluvial origin of the
Norfolk chalk, because its fragments in the shape of detritus
occur in the cliffs at Cromer ; but a precisely analogous fact has

the relative Age of Tertiary Deposits. 533

been brought forward to support a similar opinion regarding
the upper division of the crag.

A small series of shells which I had collected at Ramsholt
were placed by Mr. Lyell in the hands of M. Deshayes, for the
purpose of ascertaining his opinion with regard to the pro-
portion of extinct species. The conclusion he came to was
that the per centage of recent shells was the same as in the
larger collection, which he had examined when preparing his
tables on tertiary fossils, and which were probably obtained
from the upper bed.

It is in allusion to this circumstance that a correspondent
observes, “If such be the fact, there is an end to the question
between my opponent and myself.”

Now, the questions which have been under discussion are the
presence of corallines in the Ramsholt bed, and the diluvial na-
ture of the red crag. To decide these disputed points by sim-
ply ascertaining the per centage of extinct species in the shells
of the coralline crag, can only have been effected by a course of
induction as novel in its nature as the results which it evolves
are important; nor shall I stand alone in anxiously anticipating
further information upon the application of a principle, which
in some instances may so materially assist the labours of the
geologist while prosecuting the investigation of tertiary for-
mations.

I turn however from the consideration of this subject, which
is almost devoid of interest from its not having assumed a
form that entitles it to serious discussion, to enter upon an in-
quiry far more comprehensive in its nature and requiring a
more profound method of investigation ;—an inquiry replete
with the highest interest, from the practical suggestions which
it offers, and still more so in the field which it throws open
for legitimate inductive speculation.

I have on a previous occasion dwelt upon the features which
separate the coralline crag from the tertiary strata with which
itis connected. The novelty of its general aspect, lithological
character, and organic remains when contrasted with the ad-
jacent fossiliferous beds cannot be disputed. But the ques-
tion may fairly be asked, what is the nature of these changes,
and what are the conclusions to be drawn from them?
Do they accord with those well-known phenomena which are
supposed to register the lapse of ages; or may they not rather
be attributed to certain alterations in physical condition, which.
over a small area may materially affect the existing organiza-
tion during a comparatively short ‘period ?

I am aware that Mr. Lyell in the last edition of his Prin-
ciples of Geology refers the red and the coralline crag to the

534 Mr. Charlesworth on the Crag, and on ascertaining

same period, from the number of fossils which are common to
the two deposits, and this opinion he has subsequently con-
firmed in the Anniversary Address recently delivered to the
Fellows of the Geological Society.

In a former memoir, when describing the stratum at Rams-
holt, the opinion I stated was that it formed part of a de-
posit, older, geologically speaking, than those shelly strata
above it with which geologists were already familiar. Subse-
quent consideration has tended to strengthen the views which
I then advocated, and my object at present is that of testing
the importance of those facts which are supposed by some to
identify the coralline beds with the other fossiliferous strata.

During the summer of 1835, I entered upon a more minute
examination of those localities in which the inferior portion of
the crag is most advantageously exposed, and my investiga-
tion has been attended with results of a highly gratifying and
satisfactory nature. I have procured from Ramsholt every
species of coral that has yet been obtained from the more ex-
tensive excavations at Aldborough and Orford; while above
the coral reefs, which occupy so large a portion of the latter
district, I have succeeded in discovering the upper deposit,
still retaining those well-marked peculiarities which form a
striking contrast to the inferior stratum, and from which even
the yet unpractised observer would as naturally separate it as
he would the beds of the coralline crag from the London clay
on which they repose. My anticipations on this subject have
therefore been completelyrealized, and the true geological posi-
tion of the Orford crag may now be considered fully established.

The relative position and lithological character of the red
crag would during a late period of inquiry have probably as-
signed it a distinct place in a geological series, and under some
circumstances the geologist undoubtedly derives considerable
assistance in the classification of fossiliferous deposits from a
careful observation of these phenomena. To guide our deter-
mination in the instance before us, in addition to these sources
we have thrown open to our inspection an extensive series of
organic remains; it is from their examination that my own
opinions have principally been formed, and it now remains
for me to show how far they can be justified. j

With this view I shall take a cursory survey of the organic
remains at present discovered in the tertiary strata which over-
lie the London clay in Suffolk and the chalk in Norfolk.

In the coralline crag we find few indications of the exist-
ence of vertebrated animals; such as are met with belong ex-
clusively to the class of Fish; but the nature of this deposit ap-
pears to have been by no means well calculated for the pre-

the relative Age of Tertiary Deposits. 535

servation of their remains. ‘The only bones of frequent oc-
currence are those placed within the cavity of the tympanum,
and which being of a more solid texture than the rest of the
skeleton are found in a very perfect state. These bones belong
to an unknown genus, and are peculiar to this part of the crag
formation. Teeth of cartilaginous species are occasionally met
with, but in the course of my own researches I have never suc~
ceeded in obtaining them.

The ocean, however, which deposited the red crag was one
evidently swarming with fish; and their mineralized remains,
generally consisting of the teeth and portions of the palate,
are preserved in great abundance. Among them are the ge-
nera Carcharias, Myliobates, Galeus, Lamna, Notidanus, and
Platax, &c. Wherever this deposit is detected, some of
these genera invariably accompany it. Itis here also that we
first meet with the higher orders of the animal kingdom. The
teeth of the Mastodon, Elephant, Hippopotamus, and other
Mammalia are deposited with the Mollusca of this period, and
in addition to them I may mentioned the bones of Birds, which
I have recently obtained from several localities.

Turning from the groups of vertebrated animals to those
of the Radiata, we naturally revert to that extensive assem-
blage of Polypifera which characterize so large a portion of
the coralline crag, and to which nothing analogous is pre-
sented by any other tertiary deposit in this island. ‘The
Echinide too, so sparingly distributed in the London clay
and upper beds of the crag, are here met with in compa-
rative abundance; fragments and spines are of constant oc-
currence, and some of the more perfect specimens which have
been obtained exhibit the most elegant forms, and are widely
removed from known species. ‘There are one or two spots
in the red crag where Echini have congregated in myriads,
but the species approximate more nearly to those now exist-
ing, and with which they may perhaps be identified. The com-
parison of the Crustacea from the two beds has furnished a
corresponding result; but the remains of this group are spa-
ringly met with, and generally in an unfavourable state for ex-
amination.

I now proceed to notice that class which among organized
beings are thought to furnish the geologist with the most im-
portant data in his investigation of tertiary formations, and to
which he especially directs his attention when fossiliferous
strata of different periods are superposed in the same area, or
when he is desirous of ascertaining the probable epoch to
which an isolated deposit should be referred.

Mr. Searles V. Wood, who possesses the largest series extant

536 Mr. Charlesworth on the Crag, and on ascertaining

of British tertiary fossils,states that he has collected 450 species
of shells from the crag: of these more than 200 were peculiar
to the coralline, 80 peculiar to the upper bed, and 150 were
found in both deposits.

Before any conclusions are drawn from this statement, it is
of the utmost importance to bear in mind the circumstances
under which the fossils of one formation may, by the natural
process of degradation, have been imbedded in another. I
have before alluded to the fact of secondary shells occurring
in the red crag where that deposit is in contact with the chalk;
and if causes similar to those now in action were operating at
eras antecedent to the present, there is nothing to excite our
surprise in this phenomenon. I have been particularly struck
with the appearance presented by the fossils in those remark-
able masses of transported or protruded chalk which are seen
on the beach for a few miles east of Cromer. Many of these
enormous fragments are half buried in the stratum of blue
clay forming the beach, to which level the elevated portion is
by the action of the tides gradually reduced. A platform of
chalk is thus formed, which is frequently studded in every di-+
rection with Belemnites and Terebratule. As its surface wears
away the fossils are brought out in relief, and at length being
entirely removed are deposited with the recent Mollusca. The
point principally deserving notice here is the introductien of
these fossils into the present deposits completely detached from
the matrix in which they were imbedded, and which being re-
moved in a finely divided state, would not at a future period
be recognised in the form under which it formerly existed.

The secondary shells in the crag of Norfolk have probably
been removed from their original bed by a process similar to
that just described. We see no indications of a more violent
operation ; there are no nodules of chalk accompanying the
fossils, which are themselves so completely freed from an
adherent matrix that they can only be distinguished from the
more recent Mollusca with which they are associated by an
attention to specific distinctions, and by the chalk locked up
within the cavity of the bivalves.

At the time the formation of the red crag was going for-
ward, the surface of the chalk to a great extent was protected
from abrasion by overlying deposits, and wherever this was
the case the superior stratum would be the one exposed to
denudation, and from which organic remains would be trans-
ported. In this way, undoubtedly, have the fossils of the co-
ralline crag, along with those of the chalk, been introduced
into a more recent deposit, and the difficulty is now to ascer-
tail the probable amount of admixture. Connected with this

the relative Age of Tertiary Deposits. 537

subject there is one circumstance which should not be passed
over without consideration: supposing that the disturbing
forces were acting with equal intensity over the area of chalk
and coralline crag, the effect produced, so far as regards the
removal of fossils, would be regulated by their abundance and
by the nature of the deposit in which they were imbedded. If,
as is really the fact, we find in the red crag six or eight per
cent. of fossils belonging to the chalk, we may reasonably infer
the presence of a much larger number derived from the coral-
line beds. Were we to discover fossil shells carried down to
the delta of a river the course of which flowed over an equal
area of chalk and crag, we should naturally expect that the
majority of these transported fossils would belong to the latter
formation.

The numerical statements drawn up by Mr. Wood have
been made without any reference to the conditions under
which a large number of the same fossils have been disco-
vered in the two deposits. However abundant or naturally
grouped a shell may occur in the coralline crag, one solitary
specimen of that species, or even a fragment having been de-
tected in the upper bed, at once places it on the list of those
which are spoken of as common to the two formations; under
these circumstances, and taking intoconsideration the probable
extent to which the coralline beds have been broken up, I am
only surprised that there should be so large a number as 200
species which are only found in them and have not yet been
observed in the rest of the formation.

There are however some Mollusca which are either naturally
localized, or occur in the same abundance in both divisions of
the crag formation; and setting aside the fallacies which may
arise from our erroneous identification of species, we are at
liberty to infer from these the probable approximation of the
two deposits. It appears, however, that a very large proportion
of species may be continued through distinct and very remote
geological epochs, for on referring to the tables of M. Des-
hayes, we find that there are not less than 40 per cent. of
species common to the crag and to the formations at this time
in progress round the British islands.

Mr. Lyell, when speaking of the newer pliocene formations,
observes in vol. iii., page 54, °¢ It will be seen that of two hun-
dred and twenty-six species found in the Sicilian beds only
ten are of extinct or unknown species, although the antiquity
of these tertiary deposits as contrasted with our most remote
historical zeras is immensely great. In the volcanic and sedi-
mentary strata of the district round Naples, the proportion
appears to be even still smaller,”

538 Sir W. R. Hamilton’s Theorem connected with the

It seems then that if instead of 20 or 30 there were 95 per
cent. of species common to the red and coralline crag, even
then these deposits might be as widely separated as the Sicilian
tertiary strata and the formations of the present period !

I have yet to enter upon the most important stage of the
present inquiry, that which relates to M. Deshayes’s examina-
tion of the coralline crag shells, and to the consideration of
how far the result affects the opinion I formerly advanced
respecting the antiquity of the Ramsholt stratum.

During the last two or three years I have embraced every
opportunity of examining the marine and freshwater deposits
in the counties of Norfolk, Essex, and Suffolk, and of late
my attention has been particularly directed to those views
of chronological arrangement which in so comprehensive
and elaborate a manner are advocated in the ‘ Principles of
Geology.’ From facts which have fallen under my own
notice during the course of my investigation, and from other
circumstances which have more recently transpired,] feel con-
fident that a classification of the fossiliferous strata in ques-
tion, founded upon the proportion of extinct Mollusca which
they individually contain, would lead to the most erroneous
conclusions.

The sources of error which I have in the present instances
detected, will, if clearly established, have a general application
in the arrangement of tertiary formations, and will probably
materially interfere with the confidence which we might other-
wise place in the accuracy of those results which are con-
nected with numerical calculations.

To enter upon a full discussion of this most intéresting and
complicated subject would greatly exceed the limits of the
present communication, and I shall therefore confine myself
to those points which are particularly connected with the
present inquiry. [To be continued.]

XCI. Theorem respecting Algebraic Elimination, connected
with the Question of the Possibility of resolving in finite
Terms the general Equation of the Fifth Degree. Extracted
by Permission, from a Communication recently made to the
Royal Irish Academy. By Professor Sir Witt1am Rowan
Hamitton, Astronomer Royal of Ireland*.

Theorem. [= x be eliminated between two equations, of the

following forms, namely, 1st, an equation of the
fifth degree, of the form
= r+Der — E, Sec eneceruesesesee (1.)

* Communicated by the Author.

Question of solving the Equation of the Fifth Degree. 539

in which the roots are supposed to be all unequal, and the
coefficients D and E to be, both of them, different from 0,
and, 2nd, an equation of the form

ep = Oa + F(a), \sennsvsieneceansiann (2.)

in which f (x) denotes any rational function of x, whether in-
tegral or fractional,
M! 2! + M"2*" + &e.
J (2) = , xz x! 3 eeeecsece (3.)

K’2* + K"2* + &e.

and if, in the result of this elimination, which will always be
an equation of the fifth degree in y, of the form

0= PLA Y4BD P4+CY+4D' y+E, «.. (4.)

we suppose that the coefficients are such as to satisfy, znde-
pendently of Q, the second as well as the first of the two con-
ditions

Be! Ose WHO Silasctgapnciss Sasa » (5.)

in virtue of the values of the constants
MM’, MY, on tly polly woe K/, KY, wee 2t'y 20!', wee vee (6.)
in the rational function f(z); Isay that then those constants

(6.) must be such as to admit of our reducing that rational
function to the form

SF (2) = Ge+(2?+Dx+E). 9 (@), occoee (7.)
g being some new constant, and ¢ (x) being some new rational
function of x, which does not contain the polynome 2°+ Dx
+E as a divisor.

Demonstration.—Let 2x, %22%3%4%; denote the five roots of
the equation (1.), which are supposed to be all unequal among
themselves, and different from 0; and let us put for abridge-
ment

fle) — fe) =h |
F (#2) — 2S (2s) = as |
Fes) — F(x) = Ie» F seseonneetennan (8.)
F(t) =F (ts) = has |
LE) = 4 Q+9=Q. |

540 Sir W. R. Hamilton’s Theorem connected with the
We shall then have
fm) =4t+7%, S (®o) = figt 725 f (U3) = Ag+ %35f (24)
— hy+q X49 S (4s) i 7X59 e@ecvceoce (9.)
and the result (4.) of the elimination of « between the equations
(1.) and (2.), may be expressed as follows :
0 = (y-Q’ #,—hy) (y—Q! x.—hg) (y—Q! x3—hs)
(y—Q’ xy—hy) (Y—Q’! 5). seveeneee (102)
Comparing (10.) with (4.), and observing that the form of
the equation (1.) gives the relations
oO = Ly PLgoALst+ Xyt 255 erecsvece (11.)
O = By otha Ug t%3 Xyt%yUyt+%5 2,
HX Pet ly Lyb Myst Hy LAH; Wyy eevee (12.)
O H 2 XX yHXqg Ug Uy 3 Uy U5 TX Xs Uy +25 2 Lo
4H, Ug ¥y+ Xo LL +Hy Us XU, +H, H, Let Xe XyXyzy (138.)
we easily find these expressions for A’ and C’, namely,
A! — (hi thgthz+h,) 5 eoecesccccee (14)

and
C= — Q? (hv thy xg ths xg + hy ry)
+Q! hy hg (x +X) +h hg (x +23) + hy hy (ay +24) \
thighs (q+ 3) thigh, (&o + 4) thy hg (%3 +24)
— (Ay highs +h, hghy+hy hg hythg hz hg) severe (15.)
If, then, the coefficient C’, as well as A’, is to vanish inde-
pendently of Q, and consequently of Q’, we must have the
four following equations :
= hth ths+hy; Peco eee res see ser ees eernes ose (16.)
0 = har thy re ths ay t+hy tgs cevvesecseeeeee (17)
0 = hy hy (4, +X_) +h hy (x, +3) +h, hy (2, +4)
thighs (%q+ a3) +hohg (@o+a4) +h hy (x3+%4)3 (18.)
0 = Ay hghsthyhghythy hghythghghy3 serve (19.)
which give, by elimination of ,,
0 = hy, (wP—a2P) +h (x—aP) +hs(xy—xy), — (20-)
0 = ha, the xoths x34 (hithgths)? x45 (21.)
O = hathy) (hg +h) (hy tha) + ceveveccecceceeeseeee (22.)
Of the three factors of the last of these equations, it is mani-
festly indifferent which we employ ; since the conclusions which
can be drawn from the consideration of any one of these three
factors can also be drawn from the consideration of either of

the other two, by merely interchanging two of the three roots
21 X_ Xz, without altering the other of those three roots, or

Question of solving the Equation of the Fifth Degree. 541

the two remaining roots x, x, of the equation (1.). We shall
therefore take the first of the three factors of (22.), namely,
the equation

O = hgthys cseccccccee coveceese (23.)

which reduces the two equations (20.) and (21.) to the two
following, obtained by elimination of /,,
0 = hy (xP —axP) +h, (xe?—aX537) 5 veeeee (24)
Oe. fiy2 (a, 4074) ehg® (hg ai) om sonore (2s)
These two last equations give, by elimination of /,,

O = h,?(x1+24){ (41+ x4)(%1— 24)? + (®q + %3)(%g—H3)"} 5 (26-)
in which we cannot suppose the factor x,-+., to vanish, be-
cause the relations
oo #£°+D2,+E, 0) =2'+Da,+k, (27.)
give D = —(a+a%a,+e7x2+a, oye 28.)
B= (x, +24) (v,7+247) x, 245 :
and we have supposed that E does not vanish; and since, for
a similar reason, we cannot suppose that x,+.3 vanishes, we
see that we must conclude
h,=0, 4,=0, hk; = 0, hy = 0, (29.)
unless we can suppose that the third factor of (26.) vanishes,
that is, unless
(a, +24) (@1— 24) + (Xo +23) (2-43) = 0. — (30.)
Let us then examine into the meaning of this last condition,
and the circumstances under which it can be satisfied.
If we put, for abridgement,
Lot Lz = —a, X v3 = Bs Secvceces (31.)
the condition (30.) will become
0 = «f—a2) 1,—2,2°+r3—8+40 8; (32.)
and we shall have, in virtue of the relations (11.) (12.) (13.),
two other equations between x,, 7,, a, 6, namely,
0 = P44, (x,—a)+x7—2,0a+0°—B8, (33.)
and
0 = rp—xr ata, (a*—6)—a?+2aB; eee (34.)
between which three equations, (32.) (33.) (34.), we shall now
proceed to eliminate v, and 2,. For this purpose we may
begin by multiplying (33.) by 2,, and adding the product to
(32.); a process which gives, by (34),
0 = rP—4742, 44+2342AB, secoseeee (35.)

a relation more simple than (32.). In the next place we may

542 Sir W. R. Hamilton’s Theorem connected with the

observe that, in general, the result of elimination of any vari-
able 2 between any two equations of the forms
O=p tq xt x®t+s' a?
ace fhe? $rhet . \ (36.)
is
Oo= g 73! f qr? —2p! r pl’? +p y! gi? r+! s’ plig! x
—p! sl! gr ate q' 2 pl! rll? ¢/ r! pl’ gq''r!—2 q' 3 gl 2” +g! sg! q/?
peg? aly!!! sf yt! 9g! tof Age, ncemanvscecwvcccesces (37.)
Applying this general formula to the elimination of x, between
the equations (35.) and (33.), and making, for that purpose,

p = 234+2e8, ¢ = —2,4 7 = 0, si 1, 38

p’ = xf— xata—B, YJ =a,—a, =], ake?

we find, after some easy reductions,

O = 42,°—42,)5 a+a,* (8 &—68)+2,? (—8a2 +140 8)
+a,° (6 at*—120° B43 6°) +2, (—20°47 a3 B—7 a B*)
+a5—7 a* B+13 a? 3° — 33; Soe oer oeseesoosovecevecs (39.)

which is easily reduced by (34.) to the form

= v,°(2a'—206+(*)+a,(20°—7 a? B+a 8°) +a5&—3 ap

+5.a* 8? — 6, eceeeene eervneeeeeos (40.)
Again, applying the same general formula (37.) to the elimi-
nation of x, between the equations (34.) and (40.), by making
now
p! = —H+4+22 8, g = @?—B, w= —a, J = 1,
p= a&& —3 aA B45 0° BP —P, g”=2a°—7 a B+ 1,7” >(41.)
=2a'—2¢° B+/*,
we find after reductions,
0 = 25 a8—250 a6 84975 a f° —1850 a'* BF
41725 a B*—700 uw 654100 a8 BS ... (42)
that is,
(jes —— 25 af (a°—2 B)? (a4 —3 a B+ 2°). weevce (43.)
But this condition cannot be satisfied, consistently with the
suppositions which we have already made that neither D nor E
vanishes; because, by expressions similar to (28.), we have

D = —(a'—3 2° 6+"), E= —aB(#*—2 8). (44)

We must therefore reject the supposition (30.), and adopt
the only other alternative, namely, (29.); and hence we have,

by (9.)
S(%) = q &yy F(X) = JXoy f (x3) = 7 Xs SF (4)

= 7X45 (25 — G Use eeeeeaeeseee ( 5.)

Question of solving the Equation of the Fifth Degree. 543

In this manner we find, that, under the circumstances sup-
posed in the enunciation of the theorem, the function

J (x)—ge
vanishes, for every value of x which makes the polynome
x°+D2+E vanish; and since these values have been sup-
posed unequal, we must have, therefore,

SJ (@)—qe = (#°+De2+E). (x), ....... (46.)
the function ($ x) being rational, like f(x), and not containing
x2°+D2+E as a divisor; which was the thing to be proved.

Corollary. It is evident that, under the circumstances

above supposed, the coefficients B! D! E! of (4.) will be ex-
pressed as follows:

BS OP Ca ey Ore eee. (47.)
that is, the equation of the 5th degree in y will be of the form
0 = 7+Q*Dy+Q°E. ...... vows (48.)

At the same time the relation between y and «x will reduce
itself, by (2.) and (7.), to the form
y = Ucrt(2?+Dx+E). 9 (x), ...... (49.)

Q still denoting Q+g. If, then, we were to establish this
. additional supposition

Dh ei BERT. Sb altiducets 0 GD

in order to complete the reduction of (4.) to De Moivre’s
solvible form, we should have

that is,
GY ess Pyitracalita oes, otste sewee (52)
the equation of the fifth degree in y would become
Gt, rh leahann ch tnighen ah prarmetbanl sks (53.)
and the relation between y and x would become
¥y =(P +DrtE).¢ G3 «2-0 (54.)
and thus, although the equation in y would indeed be easily

solvible, yet it would entirely fail to give any the least assistance

towards resolving the proposed equation of the fifth degree
in 2.

Observatory, Dublin, May 15, 1836.

[ 544 ]
XCII. Reviews, and Notices respecting New Books.

The Principles of Hydrostatics. By Thomas Webster, M.A., of

Trinity College, Cambridge. 1835.
The Theory of the Equilibrium and Motion of Fluids. By the same

Author. Cambridge, 1836.

N the Preface to the first of these works Mr. Webster states that he

has ‘¢ endeavoured to develop the principles of the science of Hydro-

statics with the use of none but the most elementary mathematics ;
so that the student, who now either partially or wholly neglects this
beautiful branch of natural philosophy from the uninviting character
which analysis presents, to those who are not familiar with it, may at
once proceed to its study if he is only acquainted with the first prin-
ciples of algebra and mechanics. It is not from thinking other me-
thods preferable or even comparable with the analytical that I have
adopted this plan, but with the view of bringing the subject within
the reach of those who have not been initiated in analysis.” By pur-
suing this plan the author has produced a work of more general utility:
than if he had introduced more analytics, since many that might not
have ability or inclination to follow a train of reasoning conducted by
mathematical symbols, would take interest in and receive benefit from
an exposition of the principles on which such reasoning may be
founded, and by a statement of facts and results. Besides which,
the nature of the work admits of the introduction of subjects which
in the present state of science do not admit of exact mathematical
treatment, and which are nevertheless fully as useful in a practical
point of view, or instructive as branches of natural philosophy, as
many of. those that do, These subjects are, Steam and its applica-
tions ; the mechanical application of the Motion of Fluids ; Dalton’s
law of the diffusion of Gases coexisting in the same space ; Winds ;
Trade Winds ; Evaporation; Theory of Rain, &c., which will be found’
to be clearly and concisely treated in this work. It adds, however,
to the confidence we place in works of this description to know that
they are written by mathematicians. Mr. Webster establishes a
claim to being considered such by the able manner in which the se-
cond of the above-named treatises is composed, which is purely ma-
thematical, being intended to carry the student to the highest analy-
tical deductions from the first principles of hydrostatics and hydrody-
namics that could be prudently introduced into an elementary work.
Accordingly, besides the usual propositions, treated for the most part
in the usual manner, there is additional matter on subjects that have
scarcely yet acquired a standing in elementary treatises, viz. Laplace’s
Theory of Capillary Attraction, Specific Heat, and the Law of Cool-
ing, in the statical part; aerial vibrations and their propagation,
considerd as the immediate causes of sound, together with musical
vibrations in cylindrical tubes, in the dynamical part. In these por-
tions of the work Mr. Webster has drawn largely from recent me-
moirs both of foreigners and our own countrymen, and has endea-
voured to make their productions more accessible to the mathematical
student by breaking up the simpler parts into distinct propositions.

Royal Society. 545

As these subjects are inferior to few in the interest that attaches to
them, and would be more generally attended to if the mathematical
calculation by which the reasoning in most of them is necessarily
conducted could be simplified, any attempt, like that in the work
before us, to do this, is deserving of our approbation.

XCIII. Proceedings of Learned Societies.

ROYAL SOCIETY.

1836. PAPER was read, “ On an artificial Substance resem-
Feb, 25.— bling Shell; by Leonard Horner, Esq., F.R.S. L.
and Ed.: with an account of the examination of the same; by Sir
David Brewster, K.H., LL.D., F.R.S., &c.”’

The author, having noticed a singular incrustation on both the in-
ternal and external surfaces of a wooden dash-wheel, used in bleach-
ing, at the Cotton Factory of Messrs. J. Finlay and Co., at Catrine,
in Ayrshire, instituted a minute examination of the properties and
composition of this new substance. He describes it as being compact
in its texture, of a brown colour, and highly polished surface, with a
metallic lustre, and presenting in some parts a beautiful iridescent
appearance: when broken, it exhibits a foliated structure. Its ob-
vious resemblance, in all these respects, to many kinds of shell, led
the author to inquire into its intimate mechanical structure, and into
the circumstances of its formation. He found, by chemical analysis,
that it was composed of precisely the same ingredients as shell ;
namely, carbonate of lime and animal matter. The presence of the
former was easily accounted for ; as the cotton cloths which are placed
in the compartments of the wheel, in order that they may be tho-
roughly cleansed by being dashed against its sides, during its rapid
revolutions, have been previously steeped and boiled in lime water,
But it was more difficult to ascertain the source of the animal matter;
this, however, was at length traced to the small portion of glue, which,
in the factory where the cloth had been manufactured, was employed
as an ingredient in forming the paste, or dressing, used to smooth
and stiffen the warp before it is put into the loom. These two ma-
terials, namely lime and gelatine, being present in the water in a state
of extreme division, are deposited very slowly by evaporation; and
thus compose a substance which has a remarkable analogy to shell,
not only in external appearance, and even pearly lustre, but also in
its internal foliated structure, and which likewise exhibits the same
optical properties with respect to double refraction and polarizing
powers.

A letter from Sir David Brewster, to whom the author had sub-
mitted for examination various specimens of this new substance, is
subjoined ; giving an account of the results of his investigations of
its mechanical and optical properties. He found that it is composed
of laminz, which are sometimes separated by vacant spaces, and at
others, only slightly coherent; though generally adhering to each

Third Series. Vol, 8. No. 50, Supplement. June 1836, 31

546 Royal Society.

other with a force greater than that of the lamine of sulphate of lime,
or of mica ; but less than those of calcareous spar. When the ad-
hering plates are separated, the internal surfaces are sometimes co-
lourless, especially when these surfaces are corrugated or uneven ;
but they are almost always covered with an iridescent film of the
most brilliant and generally uniform tint, which exhibits all the va-
riety of colours displayed by thin plates or polarizing lamine. This
substance, like most crystallized bodies, possesses the property of
refracting light doubly ; and, as in agate and mother-of-pearl, one of
the two images is perfectly distinct, while the other contains a con-
siderable portion of nebulous light, varying with the thickness of the
plate, and the inclination of the refracted ray. Like calcareous spar,
it has one axis of double refraction, which is negative ; and it gives,
by polarized light, a beautiful system of coloured rings. It belongs
to the rhombohedral system, and, as in the Chaux carbonatée basée of
Haiiy, the axis of the rhombohedron, or that of double refraction, is
perpendicular to the surface of the thin plates. As mother-of-pearl
has, like arragonite, two axes of double refraction; this new sub-
stance may be regarded as having the same optical relation to cal-
careous spar that mother-of-pearl has to arragonite.

The flame of a candle, viewed through a plate of this substance,
presents two kinds of images; the one bright and distinct, the others
faint and nebulous, and having curvatures, which vary as the incli-
nation of the plate is changed: the two kinds being constituted by
oppositely polarized pencils of light. On investigating the cause of
these phenomena, Sir David Brewster discovered it to be the imper-
fect crystallization of the substance ; whence the doubly refracting
force separates the incident light into two oppositely polarized pen-
cils, which are not perfectly equal and similar. In this respect, in-
deed, it resembles agate, mother-of-pearl, and some other substances ;
but it differs from all other bodies in possessing the extraordinary
system of composite crystallization, in which an infinite number of
crystals are disseminated equally in every possible azimuth, through
a large crystalline plate; having their axes all inclined at the same
angle to that of the larger plate, and producing similar phenomena
in every direction, and through every portion of the plate: or this re-
markable structure may be otherwise described, by saying that the
minute elementary crystals form the surfaces of an infinite number of
cones, whose axes pass perpendicularly through every part of the
larger plate.

An examination of the phenomena of iridescence afforded by this
new substance, leads him to the conclusion that the iridescent films
are formed at those times when the dash-wheel is at rest, during the
night, and that they differ in their nature from the rest of the sub-
stance. These phenomena illustrate in a striking manner some ana-
logous appearances of incommunicable colours presented by mother-
of-pearl, which had hitherto baffled all previous attempts to explain
them ; but which now appear to be produced by occasional intermis-
sions in the processs by which the material of the shell is secreted
and deposited in the progress of its formation.

Royal Society. 547

March 3.—A paper was read, entitled, “‘ Researches on the Tides.
Fifth Series: On the Solar Inequality and on the Diurnal Inequality
of the Tides at Liverpool.” By the Rev. William Whewel!, F.R.S.,
Fellow of Trinity College, Cambridge.

The inequality both in the height and time of high water in the
morning and evening tides of the same day, which varies according
to a law depending on the time of the year, is termed by the author
the diurnal inequality, because its cycle is one day. The existence of
such an inequality has often been noticed by seamen and other ob-
servers ; but its reality has only recently been confirmed by regular
and measured observations ; and its laws have never as yet been cor-
rectly laid down. The author gives an account of the observations
now in progress at different ports, from which he expects they will be
ascertained with great precision. He traces the correspondence of
the observations of the diurnal inequality already made with the equi-
librium theory; and remarks that the semi-diurnal tides, alternately
greater and less, which are transmitted from the Southern Ocean to
Liverpool, may be compared to the oscillations of a fluid mass: and
that they are augmented by the action of the forces occurring at in-
tervals equal to those of the oscillations. Hence the oscillations go
on increasing for a considerable period after the forces have gone on
diminishing, and reach their maximum a week after the forces have
passed theirs.

The remaining sections of this paper are devoted to the investiga-
tion of the Solar inequalities at Liverpool. By carefully elimiziating
the Lunar effects, which the author is enabled to do by the aid of the
preceding researches, he has determined the approximate circum-
stances of the Solar correction for the height. He has also obtained
evidence of the existence, and some knowledge of the laws of the
Solar inequalities of the times ; and these inequalities, as thus dis-
covered, are found to exhibit the same general agreement with the
equilibrium theory which has been disclosed in all the inequalities
hitherto detected. The results of the extensive observations now ob-
tained are sufficiently precise to indicate the defects of our mathema-
tical theories of hydrodynamics ; and some of these are pointed out
by the author, who remarks that although a short time ago the theory
was in advance of observation, at present observation is in advance
of theory ; which mathematicians are therefore called upon to re-
model and perfect.

The author proceeds to consider the effect of the Moon's declina-
tion on the Tides at Liverpool; which, as before observed, it is ne-
cessary to eliminate, in order to obtain the Solar inequality; and
gives an explanation of various formule and tables constructed for
that object. He then investigates the laws of the solar inequalities,
first, as to the heights; and secondly, as to the times of high water at
Liverpool, by applying to them these methods of calculation.

March 10,—* Report of Magnetic Experiments tried on board an
Iron Steam-Vessel, by order of the Right Hon. the Lords Commis-
sioners of the Admiralty.”” By Edward J. Johnson, Esq., Commander,
R.N., accompanied by plans of the vessel, and tables showing the ho-

312

548 Royal Society.

-‘rizontal deflection of the Magnetic Needle at different positions on
board, together with the dip and magnetic intensity observed at those
positions, and compared with that obtained on shore with the same
instruments. Communicated by Captain Beaufort, R.N., F.R.S.,
Hydrographer to the Admiralty; by command of the Right Hon. the
Lords Commissioners of the Admiralty.

This report commences with a description of the iron steam-vessel,
the “ Garryowen,” belonging to the City of Dublin Steam Packet
Company, and built by the Messrs. Laird, of Liverpool. She is con-
structed of malleable iron, is 281 tons burthen, and draws only 54
feet water, although the weight of iron in the hull, machinery, &c.
is 180 tons.

This vessel was placed under the directions of the author, in Tar-
bert Bay, on the Shannon, on the 19th of October, 1835, for the pur-
pose of investigating its local attractions on the compass. The me-
thods which were adopted with that view are given ; together with
tables of the results of the several experiments, and plans of the va-
tious parts of the Garryowen. The horizontal deflections of the
magnetic needle at different situations in the vessel were observed,
for the purpose of ascertaining the most advantageous place for a
steering compass, and also for the application of Professor Barlow’s
correcting plate: and the dip and intensity in these situations were,
at the same time, noted.

An experiment is detailed, showing that where several magnetic
needles, freely suspended, were placed upon the quay, in Tarbert
Bay, and the vessel warped from the anchorage towards them, first
with her head in that direction and then with her stern, opposite de-
flections were produced: in the first case all the needles showing a
deviation to the eastward, and in the latter to the westward, of the
true magnetic meridian.

Considering the height of the general mass of iron in the vessel
and also that of the head and stern, together with the distance (169
feet) at which some of the needles indicated a deviation, the author
concludes that the respective deflections were caused by the magnetic
influence of the iron in the vessel ; the combined effect of that about
the bows representing the north pole of a magnet, and that about
the stern a south pole. Hethen offers several suggestions for future
observation on this subject, and connected with the little oxidation
that is reported to have taken place in the vessel.

The experiments having been interrupted by a continuance of wet
and stormy weather, the author proceeds to draw the following gene-
ral practical conclusions, deduced from the series of observations
already made, and points out the further experiments which he con-
siders necessary to be tried.

Ist. The ordinary place for a steering-compass on board ship is
not a proper position for it in an iron steam-vessel.

2nd. The binnacle-compass in its usual place on board the Garry-
owen is too much in error to be depended upon.

3rd. In selecting a proper position for a steering-compass on board
iron steam-vessels, attention should be paid to its being placed, as

Royal Society. 549

far as is practicable, not only above the general mass of iron, but also
above any smaller portions of iron that may be in its vicinity; or such
portions of iron should be removed altogether.

4th. The steering-compass should never be placed on a level with
the ends either of horizontal or of perpendicular bars of iron.

5th, Theextreme ends of an iron vessel are unfavourable positions,
in consequence of magnetic influences exerted in those situations.
The centre of the vessel is also very objectionable, owing to the con-
necting rods, shafts, and other parts of the machinery belonging to
the steam-engine and wheels, which are in continual motion; inde-
pendently of the influence exerted by the great iron tunnel in this
part of the ship.

6th. No favourable results were obtained by placing the compass
either below the deck, or on a stage over the stern.

7th. It was found that at a position 203 feet above the quarter-
deck, and at another 134 feet above the same level, and about one
seventh the length of the vessel from the stern, the deflections of the
horizontal needle were less than those which have been observed in
some of His Majesty’s ships.

The author proceeds to point out various methods of determining,
by means of a more extended inquiry, whether the position above
indicated, or one nearer to the deck, is that at which the steering-
compass would be most advantageously placed.

The concluding section contains an account of some observations
made by the author on the effects of local attraction on board dif-
ferent steam-boats, from which it appears that the influence of this
cause of deviation is more considerable than has been generally ima-
gined; and he points out several precautions which should be observed
in placing compasses on board such vessels.

“ Researches on the Integral Calculus. Part I.” By Henry Fox
Talbot, Esq., F.R.S.

The author premises a brief historical sketch of the progress of
discovery in this branch of analytical science. He observes that the
first inventors of the integral calculus obtained the exact integration
of a certain number of formule only ; resolving them into a finite
number of terms, involving algebraic, circular, or logarithmic quan-
tities, and developing the integrals of others into infinite series. The
first great improvement in this department of analysis was made by
Fagnani, about the year 1714, by the discovery of a method of rec-
tifying the differences of two arcs of a given biquadratic parabola,
whose equation is += y. He published, subsequently, a variety of
important theorems respecting the division into equal parts of the
arcs of the lemniscate, and respecting the ellipse and hyperbola; in
both of which he showed how two arcs may be determined, of which
the difference is a known straight line. Further discoveries in the
algebraic integration of differential equations of the fourth degree
were made by Euler; and the inquiry was greatly extended by Le-
gendre, who examined and classified the properties of elliptic inte-
grals, and presented the results of his researches in a luminous and
well-arranged theory. In the year 1828, Mr. Abel, of Christiana, in

550 Royal Society.

Norway, published a remarkable theorem, which gives the sum of a
series of integrals of a more general form, and extending to higher
powers than those in Euler’s theorem ; and furnishes a multitude of
solutions for each particular case of the problem. Legendre, though
at an advanced age, devoted a large portion of time to the verifica-
tion of this important theorem, the truth of which he established upon
the basis of the most rigorous demonstration. M. Poisson has, in a
recent memoir, considered various forms of integrals which are not
comprehended in Abel’s formula.

The problem, to the solution of which the author has devoted the
present paper, is of a more general nature than that of Abel. The
integrals, to which the theorem of the latter refers, are those com-

>

g Pd :
prised in the general expression ar where P and Rare entire po-

lynomials in z. Next in order of succession to these, there naturally
presents itself the class of integrals whose general expression is

Ff ae where the polynomial R is affected with a cubic, instead

of a quadratic radical; but Abel’s theorem has no reference to these,
and consequently affords no assistance in their solution. The same
may be said of every succeeding class of integrals affected with roots
of higher powers. Still less does the theorem enzble us to find the

sum of such integrals as /¢ (R) dz; R being, as before, any entire

polynomial (that is, containing at least two different powers of 2),
and ¢ being any function whatever. The author then details the
processes by which he arrives at the solution of this latter problem.

March 17.—A paper was read, “On the reciprocal attractions of
positive and negative electric Currents, whereby the motion of each is
alternately accelerated and retarded.” By P. Cunningham, Esq.,
Surgeon R.N. Communicated by Alexander Copland Hutchison,
Esq., F.R.S.

The author found that a square plate of copper, six inches in dia-
meter, placed vertically in the plane of the magnetic meridian, and
connected with a voltaic battery by means of wires soldered to the
middle of two opposite sides of the plate, exhibited magnetic polarities
On its two surfaces, indicative of the passage of transverse and spiral
electrical currents, at right angles to the straight line joining the
ends of the wires. The polarities were of opposite kinds on each
side of this middle line, in each surface; and were reversed on the
other surface of the plate. The intensities of these polarities at every
point of the surface were greatest the greater its distance from the
middle line, where the plate exhibited no magnetic action. The au-
thor infers from this and other experiments of a similar kind, that each
electric current is subject, during its transverse motion, to alterna-
tions of acceleration and retardation, the positive current on the one
side of the plate and the negative on the other, by their reciprocal at-
tractions, progressively accelerating each other’s motions, as they
approach, in opposite directions, the edge round which they have to
turn, After turning round the edge their motion will, he conceives,

Royal Society. 551

be checked by coming in contact with the accelerated portions of the
opposing currents to which they respectively owed their former in-
crease of velocity; so that the one current will be retarded at the
part of the plate where the other is accelerated. To these alternate
accelerations and retardations of electric currents during their pro-
gressive motion, the author is disposed to refer the alternate dark and
luminous divisions in a platina wire heated by electricity, as was
observed by Dr. Barker.

“ Meteorological Journal kept at Allenheads, near Hexham.” By
the Rev. William Walton. Communicated in a letter to P. M. Roget,
M.D., Sec. R.S.

This Journal contains a register of the height of the barometer,
taken at 9 a.m, and at 3 p.m. during every day in January and
February 1836, with remarks on the state of the weather during a
few particular days. The station where the observations were made
is elevated 1400 feet above the level of the sea.

March 24.—A paper was in part read, entitled “ On the Tem-
peratures and Geological Relations of certain Hot Springs ;_ particu-
larly those of the Pyrenees ; and.on the Verification of Thermometers.”
By James David Forbes, Esy., F.R.S., Professor of Natural Philosophy
in the University of Edinburgh.

The Society then adjourned over the Easter vacation, to meet again
on the 14th of April.

April 14.—The reading of Professor Forbes’s paper, “ On the
Temperatures and Geological Relations of certain Hot Springs ; par-
ticularly those of the Pyrenees; and on the Verification of ‘Thermo-
meters,’’ was resumed and concluded.

The author expresses his regret that notwithstanding the great in-
terest, more especially in a geological point of view, which attaches
to every topic connected with the origin, the nature, and the perma-
nence in temperature of the many thermal springs met with in dif-
ferent parts of the world, our information on these subjects is exceed-
ingly deficient. On many points which might easily be verified, and
which are of essential consequence towards obtaining a satisfactory
theory of the phenomena, we as yet possess but vague and uncertain
knowledge, It is evident that the first step towards the establish-
ment of such a theory must consist in the precise determination of
the actual temperature of each spring; from which we may derive
the means of estimating by comparative observations, at different
periods, the progressive variations, whether secular, monthly, or even
diurnal, to which that temperature is subject. We have at present,
indeed, not only to lament the total absence of exact data on which
to found such an inquiry ; but we are obliged to confess that, owing
to the difficulties which meet us even in the thresbhold, we have not,
even at the present day, made any preparation for establishing the
basis of future investigation, by applying such methods of experiment
as are really in our power, and are commensurate with the superior
accuracy of modern science, The researches of Fourier would lead
us to the conclusion that, if the high temperature of these springs
be derived solely from that of the interior portions of the earth, the

552 Royal Society.

changes which can have occurred in that temperature, during any
period to which history extends, must be so minute as to be inappre-
ciable. On the other hand, the theory of internal chemical changes,
which have been assigned as the origin of volcanos, would suggest it
as improbable that this temperature has remained constantly the
same ; and as a more likely occurrence, even were we to suppose that
no uniform secular diminution took place, that it would be liable to
occasional irregular fluctuations, The influence of earthquakes on
the temperature of hot springs is also admitted; and it would be very
desirable to learn, from a series of consecutive observations, whether
abrupt changes, similar to those which have occasionally been noticed,
are not of frequent occurrence.

The author has diligently laboured to collect, by observations made
on the spot, materials for supplying this great chasm in the natural
history of our globe. As an essential preliminary means of obtaining
accurate results, he applied himself to the verification of the scales of
the thermometers he employed in these researches: and he describes,
in a separate section of this paper, the methods which he adopted
for the attainment of this object. He first fixed with great precision
the standard points of each thermometer, namely the freezing and
boiling temperatures of water, by a mode which he specifies: and
afterwards determined the intermediate points of the scale by a me-
thod, similar to that of Bessel; namely, that of causing a detached
column of mercury to traverse the tube; but simpler in practice.
Instead of employing for that purpose columns of mercury of arbi-
trary length, and deducing by a complex and tentative process the
portions of the tube having equal capacities, the author detaches a
column of mercury from the rest, of such a length as may be nearly
an aliquot part of the length of the scale for 180°; and causes this
column to step along the tube; the lower part of the column being
brought successively to the exact points which the upper extremity
had previously occupied: so that, at last, if its length has been pro-
perly chosen, the upper end of the column is found to coincide with
the end of the scale: and this being accomplished, it is easy to apply
to every part of the actual scale of the instrument the proper correc-
tions, which may, for greater practical convenience, be drawn up in
the form of a table.

In the next section, the author gives a detailed account of his ob-
servations of the mineral springs of the Pyrenees, made during the
months of July and August, 1835, following them in their natural
order from west to east, and describing their geological positions,
the special circumstances of interest relating to them, and their
actual temperatures.

In the third and last section he extends his inquiries to the hot
springs met with in some other parts of Europe ; and in particular,
those of the baths of Mont Dor and of Bourboule, in France; of
Baden-Baden, in Germany; of Loésche, or Leuk, in the Vallais ; of
Pfeffers, in the canton of St. Gall, in Switzerland ; and the baths of
Nero, near Naples. The final results of all the observations con-
tained in this paper are presented in the form of a table, with com-

Geological Society. 553

parative columns of those derived from some unpublished observa-
tions of M. Arago, and of those of M. Anglada.

GEOLOGICAL SOCIETY.

_ (Continued from p. 160.)

Dec: 16, 1835.—A paper, entitled “‘ Notes on the Geology of Den-
mark,” by Dr. Beck of Copenhagen, and communicated by the Presi-
dent, was first read.

The only part of the Danish dominions in which gneiss and gra-
nitic rocks like those of Scandinavia appear, is in the north-east of
the Island of Bornholm. To the south and south-west of these for-
mations in the same island, are beds considered to be of the age-of
the Silurian system of Mr. Murchison; and on the eastern side of it
are strata of the cretaceous period, all the intermediate groups being
wanting.

Respecting the exact age of the lower part of the cretaceous beds
in Bornholm, much difference of opinion has existed, By some it
has been referred to the old carboniferous formation, on account of
the presence of large quantities of coal, and impressions of ferns; by
others to a lignite deposit of a very new or diluvial period; by M.
Alexander Brongniart to the age of the lias ; by Dr. Pingel to the
iron sand of Messrs. Conybeare and Phillips ; and by Dr. Beck to the
English strata, from the Hastings sand to the upper green sand in-
clusive. The fossil ferns found in these beds belong to the genus
Pecopteris, and some of the species have been named by M. Adolphe
Brongniart. The seed-vessel of a monocotyledonous plant of com-
mon occurrence in these strata, and considered by Dr. Beck to belong
to the family Restiacee, is identical with one in Mr. Mantell’s collec-
tion obtained at Heathfield in Sussex. ‘The few shells associated with
the ferns which the author has examined are marine; and he conceives
that these Bornholm beds were deposited in the sea at some distance
from the mouth of the river which formed the Wealden system of
England.

To the south of these coal-bearing strata are beds of siliceous and
calcareous sand, containing between 30 and 40 species of shells, which
also occur in the upper green sand of England: and in the neigh-
bourhood of Arnager is a small patch of greyish white chalk with very
few flints, but abundance of fossils, agreeing with those of the lower
white chalk without flints at Southerham near Lewes.

In Denmark Proper the oldest formation belongs to beds of the
cretaceous series, younger than those in the island of Bornholm.
The lowest strata consist of pure white, soft chalk, with many layers
of black, nodular flints, and contain more than 300 species of fossils.
Among these remains, Ammonites are extremely scarce, Marsupites
are unknown; and the remains of fishes, except teeth of the shark fa-
mily, are very rare: but small zoophytes and microscopic foraminifera
are very abundant; and, in some instances, animals of the sponge
tribe, replaced by flint or chalcedony, but retaining their form, con-

554 Geological Society.

stitute complete beds. This portion of the chalk series forms, very
generally, the lower part of the strata in Seeland and Jutland, and the
whole of the cliffs of Moen. But in Moen masses of gravel and sand
have, in consequence of great disturbances, become entangled with
portions of disrupted chalk, in the manner explained by Mr. Lyell in
a paper lately read before the Society*.

This white chalk is immediately overlaid, in Seeland and elsewhere,
by the Faxoe beds, consisting almost entirely of hard, yellowish
limestone, susceptible of a polish. They contain some of the cha-
racteristic fossils of the white chalk and some which are peculiar,
belonging to the genera Arca, Modiola, Venus, Trochus, Fusus, Vo-
luta, Oliva, Cyprea, Nautilus, &c.; while in the quarries at Faxoe
(Seeland) they are composed so largely of zoophytes that they may
justly be regarded as a coral reef. ‘This division of the cretaceous
series attains at Faxoe a thickness of more than 40 feet, but it is only
between 2 and 4 feet thick at Stevensklint, where it may be traced
for 3 or 4 miles resting upon the white chalk and covered by other
strata of this series. The Faxoe beds appear also in some places in
Jutland as in the Island of Mors, the cliffs near Grenaa, &c.

These beds have been imagined to be perfectly parallel to those of
Maestricht, but the organic remains differ considerably ; and are more
analogous to those found at Kiinruth near Liege. Among the fossils
common to the last locality and the Faxoe beds, are Baculites Fawasii,
Nautilus fricator (Beck), Fusus elongatus (Beck), and 7 erebratulasubgi-
gantea (Schlotheim). Dr. Beck also states that the Nautilus Danicus
is not identical with the Nautilus aganiticus of the lias, though Von
Buch considers that it is : he likewise states that he has not been able
to identify any of the Faxoe fossils with those of the oolitic series, or
with the shells of Gosau, or with any of the tertiary fossils hitherto
described.

The cretaceous beds which immediately cover the Faxoe deposit in
Stevensklint, consist of a whitish and hardish chalk, including so great
a number of broken and almost pulverised zoophytes that the rock is
sometimes entirely composed of them. The bivalves and echinoder-
mata are chiefly the same as those of the white chalk, but the univalves,
so common in the Faxoe beds, are wanting, while many of the smaller
corals which occur in those beds occur also in this upper limestone.
The flint of these superior strata is sometimes in continuous layers as
in Stevensklint, sometimes in nodules, and differs from the flint in the
white chalk in being more opake, and having a less conchoidal fracture.
Sometimes it is replaced by a bluish grey stone, composed of silex and
lime, and called in Danish “ bleger.”

Dr. Beck infers from the organic remains that the chalk of Salt-
holm; of the cliffs in Jutland, ranging from Rugaard by Daugbjerg and
Monsted, and terminating in the neighbourhood of Hjerm ; as well
as the chalk of the south of Thyholm, that resting upon the white
chalk in part of Mors and in the northof Thy; and the chalk of thecliffs
of Bulbjerg and the islet Skarreklit belongs to this uppermost bed.

* Proceedings, No. 41. Vol. II. p. 191., or Lond. and Edinb. Phil. Mag.,
vol. vii, p. 412.

Geological Society. 555

Upon the chalk in various districts in Denmark is a breccia of an+
gular fragments of chalk and flint cemented with carbonate of lime.
The chalk hills of Denmark present generally the same rounded, smooth
outline as in many parts of England, with this distinction, that in
Denmark they are crowned very commonly with small mammilliform
hillocks of gravel, sand, and erratic blocks. As the sandy beds some-
times contain shells identical with those now living in the German
Ocean, it is evident that the chalk in Denmark has been submerged
since the existence of the living species of Testacea.

In Bornholm, Moen, and Seeland, the strike of the cretaceous strata
is dependent on the strike of the most ancient granitic rocks in Scania;
but in Jutland it is not parallel to them, and evidently was not caused
by the same system of movements.

In the central parts of Jutland is an extensive formation several
hundred feet thick, referred by Dr. Beck to tertiary strata probably
older than the erratic blocks. It consists in some localities of white
micaceous sand, in which occasionally occur traces of brown coal, and
near Skanderberg is a considerable layer of it. In other districts
the formation is composed of clay, which also contains mica, flat
masses of hydraulic limestone, like the septaria of the London clay,
and occasionally a few organic remains, consisting of scales of fishes
apparently belonging to the Cyprinide; the elytra of beetles, the
cases of the larve of Phryganza, and an hymenopterous insect which
the author has called Cleptis Stenstrupii. In the neighbourhood of
Thisted at Thye, the north of Mors and in the island Fir, Dr. Beck
observed, in 1831, dislocations which affect equally these tertiary strata
and the chalk.

To the tertiary period belong also the beds discovered by Professor
Forchhammer in the island of Sylt, on the western shores of Holstein.
Some of the few shells hitherto detected in them Dr. Beck has ascer-
tained to agree with characteristic fossils of the London clay, and
others, as Voluia Lambertii, with shells of the crag.

To the same older tertiary period the author is inclined to refer the
strata containing Valvata, Gyrogonites, &c., detected at Segeberg, and
the deposit between Altona and Geuchstad in which Mr. Lyell disco-
vered a valve of a Cardita.

Newer than any of the above-mentioned formations are the deposits
of gravel, sand, and loam, often several hundred feet thick, which ge-
nerally cover the older strata, and constitute almost the whole surface
of Denmark. In and upon these beds, the erratic blocks so common
in that kingdom first appear. They consist principally of the commoner
varieties of the gneiss and granitic schists of Scandinavia; but in the
neighbourhood of Copenhagen Dr. Beck has observed blocks of trans-
ition limestone, basalt with olivine, and the well-known secondary
sandstone of Hor. In the northern part of Jutland he has also no-
ticed blocks of Elfadal porphyry, and the blue zircon-syenite of Fre-
dericksvaern in Norway. The gravel beds with erratic blocks rarely
contain any fossils, but when shells do occur, they are often absolutely
identical with living species. Dr. Beck has, however, found at Moen
a specimen of Pleurotoma, which he believes to be tertiary, and there

556 Geological Society.

and at Himlingoie several specimens of Turritella not hitherto known
as living.

From the difference of the fossils, together withthe manner in which
the gravel beds are disposed upon the chalk, he infers that the older
strata have been elevated and submerged more than once.

Dr. Beck says that space does not permit him to give his views re-
specting the erratic blocks, and he merely states that their depo-
sition took place after the beginning of the tertiary period, and went
on during the accumulation of blue marl and sand, from which he has
obtained more than 70 species of shells now living in the German
Ocean; and that he has proofs, of which he intends to give a more
detailed account hereafter, that the transportation of these blocks
continues on the coast of Jutland.

In conclusion the author mentions the existence of several, small,
lacustrine formationsin the interior of Jutland and of Moen, containing
remains of Lymneza, Physa, Helix, &c. ; and an extensive formation
of sand cemented by oxide of iron.

An extract from a letter addressed to the President by H. Edwin
Strickland, Esq., F.G.S.,dated Athens, 26th Oct., 1835,was then read,

Mr. Strickland noticed first at Trieste the vast formation of secon-
dary limestone which appears to extend thence uninterruptedly into
Greece ; and of which the Ionian Islands are almost wholly composed.
In Corfu, however, are several obscure and complicated patches of
tertiary deposits, and in Cephalonia is a Pliocene formation of vast
thickness, containing abundance of fossils. Mr. Strickland then de-
scribes the currents of sea-water which constantly flow into the land
near Argostoli in the island of Cephalonia. This extraordinary phe-
nomenon occurs about a mile north of Argostoli at the very extremity
of the rocky promontory which separates that town from the large bay
on the west. The promontory is composed of the hard, white, second-
ary limestone, the strata dipping about 30° to the east ; and at this
spot it contains several species of shells which in general are rather
rare. The streams of water have been noticed for many years rushing
in between the rugged masses of rock of which the coast consists, but it
was only about two years since that they excited the attention of the
English. Mr. Stevens of Argostoli, desirous to turn them to advan-
tage, was induced to stop up three of these holes, and by excavating
a channel at the principal one, has been enabled to obtain a sufficient
supply of water to turn a mill. The channel which has been made is
about three feet wide, and the average depth of the current is six
inches. In the mean state of the tide the fall is about 3 feet, the usual
rise of the tide being 6 inches, but during southerly winds itis consi
derably more. After passing the wheel the current flows for 6 or 7
yards, and is then partly absorbed in swallow holes and partly disap-
pears under the rocks. The water at the bottom of the excavation at
greatest at high tides, the quantity of water then flowing in being
greatest. A small freshwater spring enters the excavation on the land
side, and when the sea is effectually stopped out, renders the water at
the bottom of the excavation quite fresh in the course of a day; rais-
ing it at the same time several inches to a certain point, where it rests.

Geological Society. 557

This circumstance, Mr. Strickland thinks, may be explained by the
less specific gravity of the fresh water requiring a higher column to
overcome the obstacles met with in its subterranean course. In order
to ascertain the direction of the current, Col. Brown has had an exca-
vation made, by which it appears that the stream does nct pass unddr
the sea at the opposite side of the promontory. Mr. Strickland, in
explanation of the constant flowing into the land of these streams, ob-
jects to the proposition that the subterranean current may be absorbed
by the incumbent soil and evaporated at the surface, as it occurs in an
island of small extent : but agrees to the supposition that an earth-
quake has at some period opened a communication between the sea
and the region of volcanic fire ; that the water being there converted
into steam, is afterwards condensed in its upward course, and forms
those hot-springs which exist in various parts of Greece.

A paper onthe occurrence of fossil vertebre of fish of the shark fa-
mily in the Loess of the Rhine, near Basle, by Charles Lyell, Esq.,
F.G.S., was afterwards read.

Mr. Lyell described in a memoir communicated to the Society in
May, 1834,* the geographical extent of the Loess or ancient silt of
the Rhine, as far as he had then examined it. In tracing its southern
limits during last summer, he found it in considerable force at Basle,
and still higher on the Rhine at Waldshutt, where it contains the
usual land and freshwater shells, Beyond this point he did not trace
the deposit; but from the information he received, he believes that it
terminates between Waldshutt and Schaffhausen. He here alludes
only to the loamy portion, which can be identified by its fossils ; for
the gravel beds with which the loess sometimes alternates in its lower
part, are probably of much greater extent, and are not easily to be
separated from any other ancient gravel in which bones or shells have
not been discovered.

The loess at Basle crowns the summit, and is found on the sloping
sides of several low hills which bound the valley of the Rhine; but it
is best seen one or two miles to the south of the town, in the hills
called Bruder Holz, where it rests upon nearly horizontal beds of
molasse. The loess has here an elevation of more than 1100 feet
above the sea; for it is found in places which are more than 300 feet
above the Rhine at Basle, according to the measurement of Prof.
Merian, who has also determined that the Rhine at Basle is about
760 French feet (809 English) above the level of the sea.

The principal section examined by Mr. Lyell is near the northern
extremity of the Bruder Holz below the church of the village of Bin-
ningen. The loess in this place is of its usual yellowish grey colour,
and is filled with terrestrial and freshwater shells. The lower beds al-
ternate with strata of sand and gravel, and in one of the loamy strata
of this part of the series, he found the vertebra of fish, together with
the following loess shells: Succinea oblonga, Pupa muscorum, Clau-

* See Proceedings of the Geological Society, No. 41. Vol. II. p. 83;
Jameson’s Journal, Vol. 19.; and Lond. and Edinb. Phil. Mag., vol. v.,
p. 223.

558 Geological Society.

silia parvula, Helix cellaria, H.plebeium, H. arbustorum, H. rotundata,
Bulimus lubricus, and a small Planorbis, all recent shells.

The vertebre, M. Agassiz says, belong decidedly to the Squalide
or shark family, perhaps to the genus Lamna. The one is a caudal
and the other an abdominal vertebra, each about a quarter of an inch
in diameter. They are in such a state of preservation, and of such a
colour as might be expected in bones preserved in loess, and as they
were in a bed of fine loam in which there were no extraneous fossils,
nor any fragments of rock washed out of other formations, there is
no reason to suspect that they could have been derived from the ter-
tiary molasse; and M. Agassiz also states that he has seen nothing
like them in the molasse of Switzerland, It may seem very extraor-
dinary that the first remains of fossil fish obtained from this freshwater
silt should belong to a marine genus, but M. Agassiz has informed
Mr. Lyell that both in the Senegal and the Amazon certain species
of the shark and skate families (Squalus and Raia, Linn.) have been
known to ascend to the distance of several hundred miles from the
ocean, and analogous facts are referred to in Marcgrave and Piso’s
Natural History of India.

A notice on the occurrence of selenite in the sands of the plastic
clay at Bishopstone near Herne Bay, by William Richardson, Esq.,
F.G.S., was lastly read.

The perpendicular cliff in which the selenite occurs is about a hun-
dred feet in height, and consists of the following strata :

Vegetable mould.

Reddish marl or brick earth........ 5 feet.
Mondontclaysy SSF et 20 to 30 —
Sand and sandstone.............. 60 —

The selenite is found in the sand, which, as far as the author could
determine, contains no iron pyrites or lime except in a few well-de-
fined lines of testaceous remains. The superjacent clay abounds in
pyrites, and is thickly studded with transparent crystals of sulphate of
lime, but noconnexion could be traced between the two deposits, and
the sands for five or six feet underlying the clay contain no selenite.

January 6, 1836.—A notice on the transportation of rocks by ice,
extracted from a letter of Capt. Bayfield, R.N., addressed to Charles
Lyell, Esq., P.G.S., was first read.

Capt. Bayfield says that both on the lakes of Canada and in the
St. Lawrence he has seen fragmentary rocks carried by ice. The St.
Lawrence is low in winter, and the loose ice accumulating on the ex-
tensive shoals which line each side of the river is frozen into a solid
mass, being exposed to a temperature sometimes 30° below zero.
Theshoals are thickly strewed with boulders, which become entangled
in the ice ; and in the spring, when the river rises from the melting
of the snow, the packs are floated off, frequently conveying the boul-
ders for great distances. It is also well known that stones are car-
ried by the ice. Anchors laid down within high-water mark to secure
vessels hauled on shore for the winter, are cut out of the ice on the
approach of spring, or they would be carried away. In 1834 the
Gulnare’s bower-anchor, weighing half a ton, was transported some

*

Geological Society. 559

yards by the ice, and so firmly was it fixed, that the force of the
moving ice broke a chain cable as large as that of a 10-gun brig, and
which had rode the Gulnare during the heaviest gales in the Gulf.
The anchor was cut out of the ice or it would have been carried into
deep water and lost.

With respect to rocks being transported by icebergs, Capt. Bayfield’s
testimony is equally conclusive, as he passed three seasons in the vi-
cinity of the Strait of Belleisle. In an iceberg which he examined,
boulders, gravel, and stones were thickly imbedded ; and he saw others
which owed their dirty colour to the same cause. Some of these
immense ice-islands, Capt. Bayfield thinks, had been detached from
the coast very far to the northward, perhaps from Baffin’s Bay. The
northern current brings similar masses in great numbers down the
coast of Labrador every year, and they are very frequently carried
through the straits, and for several hundred miles to the S.W. up the
Gulf of St. Lawrence.

A paper “ On the syenite veins which traverse mica slate at Good-
land eliff and chalk at Torr Eskert, to the south of Fair Head in the
county of Antrim,” by Richard Griffith, Esq., F.G.S., and P.G.S. of
Dublin, was afterwards read.

The part of Antrim to which this paper refers is situated between
Fair Head on the north, and Cushleake mountain on thesouth. The
base, or oldest formation of the district, consists of inclined strata of
mica slate passing into gneiss, and containing subordinate beds of
hornblende slate and schistose limestone. Upon the mica slate re-
pose nearly horizontal and unconformable strata of coal measures, new
red sandstone, and chalk ; andthe whole of these secondary deposits
are surmounted by an overlying mass of rudely columnar trap, the
northern extremity of which forms the magnificent promontory of
Fair Head.

Besides the hornblende schist, which is interstratified with the mica
slate and dips conformably with it, there are other rocks containing
hornblende, which appear to be imbedded in the slate, but which are
really intruded veins. On the sea-shore at Torr Point are two of these
veins, consisting of syenite and syenitic green-stone; and they may
be traced passing obliquely along the face of the stupendous and, for
the greater part, perpendicular cliff of Goodland. On the sea-shore
they appear so regular and conformable, both in strike and dip, to the
strata of mica slate, that they might be considered as integral portions
of it; but on minute inspection the syenite is found to mould into the
rough and saw-like edges of the strata of mica-slate ; and on tracing
the veins as they gradually ascend the cliff, they are found to pursue
undulating courses, neither parallel to each other nor to the lamine
of the slate, in some places approaching within four feet, and in
others being more than 20 feet apart. To the south of the fault
which traverses the cliff about 150 yards from Torr Point, the veins
reappear at a higher level than on the north of the line of dislocations ;
and between the two previously noticed is a third and smaller one.
Where first seen, this small vein is in contact with the upper surfaces
of the lower vein, from which it gradually diverges and approaches
the upper, but afterwards again descends towards the lower vein.

560 Geological Society.

The mass of the two larger veins consists of dark green, crystallized
hornblende, brownish red felspar, and occasionally quartz ; and re-
gular transitions may be traced from syenite to greenstone. When
viewed at a distance they present a rudely columnar structure. The
centre vein contains much black hornblende, some black quartz, and
presents a concretionary structure, the oval-shaped masses being en-
veloped in a congeries of pinchbeck brown mica, A tendency to this
structure is observable also in the upper vein.

Owing to the covered nature of the ground, the syenite veins of the
coast cannot be traced continuously to Torr Eskert, but by laying
down the line of the veins of Goodland cliff on the Ordnance Map,
and making due allowance for theit average inclination and the ele-
vation of the hill, Mr. Griffith entertains no doubt that the syenite in
the chalk of Torr Eskert is a prolongation of one of the syenite veins
in the slate of the cliff.

The syenite which traverses the chalk cannot be distinguished from
that of the mica slate, and passes also in syenitic greenstone. At one
point the author had a portion of the surface soil removed, and obtained
the following section:

Top... Compact chalk ..... i..57.,< erase Ee
VERE). 6 gina oie ehoicts Rio. ein tials 5 —
Chalk, irregular bed from 9 inches to 1 foot
Wiiealate, .:icishit, wad aoacgielaste

The lower bed of chalk contains quartz pebbles, green sand, and
numerous, red, siliceous grains, some of which resemble garnets. The
syenite presents large masses separated by chalk containing quartz-
pebbles, green sand, and numerous fragments of fossils. These re-
mains have nearly a vertical position when zn situ, and Mr. Griffith
consequently infers that they are not in the position in which they
were deposited.

The irregularities on the surface of the chalk are accurately filled
with the syenite: the chalk in immediate contact with the vein is
usually compact, suinetimes crystallized ; and pebbles of quartz si-
milar to those in the green sand and chalk are found occasionally in
the syenite. The author noticed a small reniform mass of syenite
imbedded in the chalk—the grain of the included portion being finer
than that of the syenite in general. Small particles of chalk were
likewise noticed in the syenite, and the union of the two rocks is so
perfect that the chalk appears to be an integral portion of a compound
deposit. Among other peculiarities exhibited at the junctionof the two
formations, the author mentions spheroidal masses of syenite in-
cludedin the chalk ; and, in conclusion, he says, that if the views which
he has put forward have been substantiated, a new and important fact
is added to those already described, which may ultimately lead us to
attribute a comparatively recent origin not only to syenite veins and
primary greenstone, but also to crystalline rocks generally when as-
sociated with schistose strata.

A letter from H. T. De la Beche, Esq., addressed to the President,
and dated Truro, the 18th of December, 1835, was then read.

This letter was accompanied by a collection of fossils from the

Geological Society. 561

schistose rocks of the North of Cornwall, and presented to the Society
on the part of the Ordnance Geological Survey. ‘

Mr. De la Beche says that in the grauwacke of Western Somerset,
Devon, and Cornwall natural divisions may be made, founded on
marked characters. How far these divisions may coincide with those
in Prof. Sedgwick’s Cambrian system he has no means at present of
judging ; but he is of opinion that the whole of the district is older
than the Silurian formations of Mr. Murchison.

Some of the organic remains obtained at Dinas Cove, in Padstow
Harbour, belong to a system of beds consisting of slates, sandstones,
and conglomerates, which encircles the northern flank of Dartmoor,
then makes a great curve south of Launceston, bends afterwards
northward round the Rough Tor and Brown Willy granite, and lastly,
again inclines southward, crossing the Padstow river to the seaon the
western coast. In various parts of this line the system is fossiliferous,
particularly where limestone occurs or calcareous matter abounds.
The Tintagel slate, long since shown by Dr. Buckland and the Rev.
John Conybeare to contain organic remains, belongs to this system.
Part of the fossils which accompanied the letter were procured from
Trevelga Island (Lower St. Columb Porth), and Towan Head near
New Quay, from the same series of beds, which, in consequence of an
east and west anticlinal line ranging by St. Eval, St. Issey, and St.
Breocks Downs, is folded over to the south, and constitutes the
schistose system of St. Columb Major, St. Columb Minor, New
Quay, &c.

The remainder of the fossils was obtained by Dr. Potts at the
western entrance of Bodmin, and by Mr. De la Beche from the vi-
cinity of Liskeard, on a prolongation of the same strata.

Altered or metamorphic rocks, having frequently the appearance of
gneiss, mica slate, hornblende rock, &c., occur in the neighbourhood
of Tintagel and Camelford; and’Mr. De la Beche says, that a little care
in tracing these rocks shows that they are altered portions of strata
which possess the usual and varied characters of grauwacke. In con-
clusion he observes, that there is every reason to believe that two
movements have taken place of the land in Somerset, Devon, and Corn-
wall, one to a height of 30 or 40 feet above the present sea-level, and
another to an uncertain depth beneath it, since the vegetation of the
land and the molluscous inhabitants of the neighbouring sea were the
same as they now are.

January 20.—A paper was read “ On the geological structure of
Pembrokeshire, more particularly on the extension of the Silurian
system of rocks into the coast cliffs of that county.” By Roderick
Impey Murchison, Esq., V.P.G.S.

This memoir was prefaced by an account of the origin of the terms
Silurian and Cambrian Systems as applied to the older sedimentary
deposits. Having occupied several years in establishing a fixed order
of succession amid the strata of age anterior to the old red sandstone,
and having finally named the formations in descending order, the
Ludlow rock, Wenlock limestone, Caradoc sandstones, and Llandeilo
flags, the author was urged by many leading geologists to propose a

Third Series. Vol.8. No. 50. Supplement, June 1836. 3K

562 Geological Society.

new, comprehensive name for this group, and thereby to prevent the
confusion which had so long prevailed by the use of the words “‘Trans-
ition” and “Grauwacke.” He adopted the term Silurian System, be-
cause the territory in which the successive formations above mentioned
are exhibited, was formerly occupied by the ancient, British people the
Silures. The Silurian rocks are underlaid by vast masses which rise
up into the mountains of North, and the western part of South Wales,
and to these Professor Sedgwick, connecting his labours with those
of Mr. Murchison, has assigned the name of ‘‘ Cambrian System.”
A portion of last summer was employed in tracing these rocks from
Caermarthenshire into Pembroke, and in doing this the author was
Jed to attempt a general survey of the county, examining the strata
from the youngest to the oldest, dwelling, however, specially on the
deposits of the “ Silurian System.”

Owing to its peninsulated form and the transverse fissures proceed-
ing from Milford Haven into the heart of the county, Pembrokeshire
affords great facilities for the comprehension of its mineral structure,
and as the chief masses range from E. to W., sections from S. to N.
expose the formations of which it is composed in descending order
from the coal-measures to the Cambrian System. The points of
novelty in the descriptions of the author apply to the persistence of
the carboniferous deposits along the coast of St. Bride’s Bay, where
they are not separated by any mass of greywacke as indicated in
former maps, the parts producing culm*, lying simply to the N.
and S. of a highly dislocated promontory of carboniferous grit.
The contortions and innumerable faults of these coal-measures being
pointed out, attention is then called to some of the probable results
of such movements in the singular accumulations of finely fractured
stone coal in small basins called ‘slashes,’ and to other vertical
downcasts of the mineral termed “sloughs.” The shale of these culm
deposits resembling in some respects certain strata of the upper Si-
lurian rocks, might to an unpractised eye appear undistinguishable ;
but even where the order of superposition is’not to be detected, essential
differences are invariably to be observed, in the coal shales never con-
taining those organic animal remains which are so abundant in the
Silurian system, whilst the latter never contains a single plant simi-
lar to those which abound in the former. Instances are cited where
by dislocations the coal measures are thrown into positions apparently
conformable to old greywacke rocks of the Cambrian system, and
hence the author surmises, that if the millstone grit and carboniferous
limestone were not present in many adjoining parts to test the true
age of these coal measures, mistakes might easily result from such
juxta-positions. Cherty and siliceous sandstones (the millstone grit)
rise in dome shapes to the west of Haverford, and occupy large por-
tions of the coal tract underlying the productive culm measures and
capping the mountain limestone.

Carboniferous Limestone.—In this formation, besides the very ac-

* All the coal of Pembroke is stone coal, and it is usually in the laminated
condition of culm,

Geological Society. 563

curate outline expressed in Mr. De la Beche’s map*, the author re-
marks the existence of a double trough of the lower limestone shale
overlying the old red sandstone in East Angle Bay ; and he particu-
larly adverts to the peculiar mineral character of these beds in Pem-
brokeshire in containing yellow and light coloured sandstones alter-
nating with shale. The fossils of this lowest member of the carboni-
ferous system are numerous, many having been furnished by the Earl
of Cawdor ; and as far as they have been yet examined they appear to
differ specifically from all the fossils of the inferior systems. The coal
measures and mountain limestone of Pembroke are singularly subject
to great faults ; one of the most remarkable of which occurs between
Johnston and Haverfordwest, where the carboniferous limestone is
thrown into a position by which it appears to overlay the coal.

Old Red Sandstone.—The upper strata of this great formation pass
upwards in many places into the shale and sandstone of the carboni-
ferous limestone, and the lowest members graduate into the Silurian
system. The great mass consists of sandy shale, here termed the “‘red
rab,” associated with red sandstones and grits ; but lithological varia-
tions from the usual typesin Herefordshire have led to the belief that
large districts (Cosheston, Williamston, Benton, &c.) consisted of
greywacke. These are yellow, grey, and greenish micaceous sand-
Stones which the author proves to be interlaced with the “ red rab,”
and to occupy the same position,as similar varieties of the rock pre-
viously described in Hereford, Radnor, &c. Some.of the coarse grits
(Canaston wood) are undistinguishable from the « greywacke ” grit
of the oldest rocks of the Cambrian system. Calcareous matter is
very sparingly exhibited, imperfect concretions or very impure “ corn-
stones” appearing only at wide intervals. The fishes so profusely de-
tected by the author in the range of the formation through Salop,
Hereford, and Monmouth, have not been observed. Amid the many
faults affecting this formation, those by which the strata ranging from
Caermarthen into Pembrokeshire have been powerfully bent and bro-
ken, and thrown into a westerly direction (Tavern Spite, &c.), are
perhaps the most striking.

Silurian System.—Though the order of superposition and the or-
ganic remains clearly attest the age of the rocks of the Silurian system,
the masses differ so much in mineral aspect from those selected as
types that it is rarely possible to subdivide them into the Ludlow,
Wenlock, Caradoc, and Llandeilo formations; but adopting the classi-
fication proposed, the author has laid down their course upon the map
as two sub-groups consisting of “ upper and lower Silurian rocks+.”

The former parting with their mudstone characters are for the most
part hard and siliceous, containing little calcareous matter, and are
never subdivided by zones of limestone as at Aymestry and Wenlock.
The lower Silurian rocks, on the contrary, are amply displayed in all

* The survey of the county was much facilitated by the possession of Mr,
De la Beche’s map of South Pembroke, which, though differing in some
points from that completed by the author, is mentioned by him as a work of
great merit for the period of its publication.

+ See Lond. & Edinb. Phil. a ph vii. p. 46, Silurian System.

3K 2

564 Geological Society.

their characteristic forms, the limestones of the Llandeilo formation
expanding to greater thicknesses (Llanpeter-Felfry, Llandewi, &c.)
than in any other part of their course, and containing many beautiful
fossils, including two unpublished species of Trilobites, common to
Caermarthenshire. The chief mass of the Silurian system ranges from
E. to W. across the county, passing by Haverfordwest, till its western
extremity subsides beneath the coal measures of Druson Haven and
St. Bride’s Bay. Other bands of it rise from beneath the old red
sandstone at Orlanton, Hoten, and Johnston ; whilst a most re-
markable zone is heaved up in an anticlinal line extending across the
most southern promontory of the county (Castle Martin Hundred),
from Fresh Water East to Fresh Water West. The most perfect
succession of the rocks of which the system is composed, is exhi-
bited in the bold coast cliffs of Marloes Bay, extending for a distance
of two miles, in which space the uppermost strata, rising at angles
of 35° to 40° from beneath the old red sandstone of Hook Point,
are succeeded by conformable, underlying masses, until the whole
graduates down and passes into the rocks of the Cambrian system
in Wooltack Park and Skomer Island. The Ludlow and Wenlock
formations can be here defined; the latter containing many well-
known fossils. The lower Silurian rocks are still more largely de-
veloped; a vast thickness of fossiliferous sandy strata being quite
identical with the “‘ Caradoc sandstones,” whilst the Llandeilo flags
with Asaphus Buchit and A, Bigsbii (a new species of the author)
occur in the haven called Moseley-wick Mouth. This coast section
is 150 miles distant from the N. eastern extremity of the Silurian
system.

The Cambrian System.—If divided by a line passing from E. to W.,
the northern half of Pembroke is exclusively composed of the older
rocks of the Cambrian system, consisting, in descending order, of

a. Dark-coloured incoherent schists, with few stone bands, no cal-
careous matter, and scarcely any traces of organic remains.
These occupy a great breadth, and, as in Caermarthenshire,
they form the beds of passage between the Silurian and the
Cambrian systems (sometimes without any break).

b. Hard grits and flagstones, coming strictly within the definition of
greywacke of German mineralogists.

c. Hard purple sandstones and schists, identical with the slaty grey-
wacke of the Longmynd, Salop, (the Lammermuir hills, Scotland,
may be cited as a good and well-known type of these rocks).

d. Slates coarse and fine, with quartz veins and concretions.

At St. David’s, Pantiphilip, and Scillyham, where the roofing-slates
are quarried, the author has detected what he believes to be a coin-
cidence between the laminz of deposit as indicated by differently co-
loured layers of sediment, and the lines of slaty cleavage; though in
the great majority of cases in Pembroke the rocks of this system,
whether consisting of sandstone, schist, or hard slate, exhibit the di-
vergences between the lines of true bedding and slaty cleavage,
so clearly and ingeniously explained by Professor Sedgwick. The
author therefore thinks it right to point to these exceptions to the

Geological Society. 565

observations of Prof. Sedgwick, because if strictly scrutinized the
phenomena are not placed in opposition to them, since it was his
belief upon the spot, that the crystallizing action which gave to these
masses their hard slaty properties produced the flaglike lamine of the
beds.

Trap Rocks.—Of these there are distinctly two classes: 1, Bedded,
and synchronous with the formation of the older rocks’; 2, Posteriorand
intrusive. Of the former there are no examples like those cited in West
Salop, Montgomery, and Radnor, (see former memoirs,) of alternation
with the strata of the Silurian system, being all confined to the Cam
brian rocks. The tract extending from Fishguard to St. David’s and the
Isle of Skomer offer illustrative examples of both these classes of trap.
In addition to the varieties of sienite, compact felspar rock (corneen
of De la Beche), greenstone, &c., of which these rocks are composed,
the author has detected crystallized chromate of iron and albite in St.
David’s Head,—small veins of copper ore also occur between Solfach
and St. David’s. Among the more remarkable changes effected by
the intrusive trap, he adverts to jaspidified schists inclosed between a
large bifurcated mass of trap proceeding from Trafgarn. Having traced
the Silurian system in a course of 120 miles from the Wrekin to Caer-
marthen in ridges more or less parallel running from N.E.to S.W., the
author has shown in former memoirs that this strike of the strata uni-
formly coincides with the direction of linear outbursts of volcanic mat-
ter. In Caermarthenshire vast dislocations and transverse breaks are
exhibited by which the strata are for short distances thrown into
E. and W. directions, but on the whole the south-westerly course is
maintained. A ridge of intrusive rocks recently discovered, ranging
between the rivers Towey and Taf (Castel, Cogan, &c.), having the
same course, serves to explain how that dominant direction has been
there preserved. In entering Southern Pembroke, however, the whole
of the strata from the coal measures to the Cambrian rocks are thrown
into an E, and W. direction, accompanied by violent contortions and
powerful faults ; whilst in northern parts of the county the old N.E.
and S.W. direction prevails. As these converging lines are accom-
panied by linear, parallel ridges of trap rock, the author is confirmed in
his belief that the forces which evolved the latter have been the proxi-
mate cause of such directions; and he further refers the extraordinary
convulsions and dismemberments to which the strata in Pembroke
have been subjected, to the interference of two great lines of ele-
vation dependent upon volcanic activity. In accordance with phe-
nomena observed in other parts of S. Wales, it is remarked that all
the superficial detritus is of local origin, the southern or lower part
of the county being partially strewed over with the debris of the rocks
which rise into mountains on the north coast. After some observa-
tions on the blown sands, and the period of their formation, the author
recapitulates the value of the Pembrokeshire coast sections in exhi-
biting the “ Silurian System” precisely in the same geological position
assigned to it from examinations in the interior ; and concludes by
stating it as his opinion, that as this one county is shown to contain
rocks in the true coal measures and in the old red sandstone, as well

566 Geological Society.

as in the Silurian and Cambrian systems, which from their lithological
characters have been mistaken for “‘ greywacke,” the use of that word
as expressing the age of rocks is no longer consistent with the ad-
vanced state of geological science, and that if used, the name should
either be rigidly restricted to some of the very oldest sedimentary de-
posits, or simply employed as a mineralogical definition of peculiar grits
which actually reoccur in strata formed in many succesive epochs.

Feb. 3.—A paper on “ The Gravel and Alluvia of S. Wales and
Siluria as distinguished from a northern drift covering Lancashire,
Cheshire, N. Salop, and parts of Worcester and Gloucester,” by R.
I, Murchison, Esq., V.P.G.S., was read.

The first part of this memoir describes the detritus in the Welsh
and Silurian territories, The surface of this region is completely
exempt from the debris of any of those far-transported rocks which
constitute what has been called ‘‘diluvium’”’ in other parts of England;
all the loose materials in S. Salop, Herefordshire, and the adjoining
Welsh counties having been derived from the Silurian and trap rocks
of the adjacent mountains. These mountains range from N.E. to
S.W., presenting inclined planes to the S.E., on the surfaces of
which the broken materials are distributed. Four of the rivers which
descend from the higher parts of Wales flow to the S.E. in accord-
ance with the prevailing lines of drift, traversing the ridges of Silurian
rocks through fissures which have resulted from dislocations of the
strata. These are the Teme, the Onny, the Lug, and the Wye, all
tributaries of the Severn. That great river, on the contrary, does not
follow the “ line of drift” to the S.E., but escapes from the mountains
to the north by a lateral gorge under the Breidden Hills; and after
a circuit in the Vale of Shrewsbury passes eastward through a narrow
transverse rent in the upper Silurian rocks and coal measures of Coal-
brook Dale; and taking its final course southward, from Bridgnorth
to the Bristol Channel, forms the eastern limit of the country covered
by the Welsh or Silurian detritus. The drainage of the Teme, Onny,
Lug, and Wye, is described in detail, with a view of showing, that in
the valleys in which these rivers descend from the mountains, the ma-
terials change with each successive ridge, the larger fragments being
transported only short distances ; and that as the gravel advances into
the plains, it becomes more finely comminuted ; Herefordshire and
the low countries being chiefly covered with local debris of the old
red sandstone. The author specially distinguishes this drift, which is
extensively spread over valleys and slopes, and sometimes found in
high situations, from the detritus which hasbeen carried down by rivers
under the atmosphere, conceiving that the former accumulations have
been washed down the surfaces of the inclined strata; because wherever
the latter dip tothe S.E.,so are the materials invariably found to have
been propelled in that direction. In no instance has any fragment
been found on the west which can have been derived from rocks on
the east. He therefore believes that at those periods when the Silu-
rian and older rocks were raised from beneath the waters, great
quantities of coarse and fine detritus were drifted down these slopes ; —
and that as the rocks on which the loose materials have been depo-

Geological Society. 567.

sited are replete with dislocations, and penetrated at many points by
ridges of trap rock, it is to be inferred, that during and after the
evolution of this volcanic matter, great and successive elevations of
the bottom of the sea took place, throwing up the drifts to the various
heights at which we now find them. As soon as the land was raised
from beneath the sea, the present rivers, it is conceived, began to flow ;
passing through the ridges by gorges produced by great lateral cracks
the result of elevation ; and that these streams have since merely trans-
ported to short distances those broken materials which were previous-
ly gathered together by subaqueous drift. To prove that the drifted
matter of each district within this region may be referred to disturb-
ances purely local, it is shown that although wherever the hills have
been elevated from N.E. to S.W. the lines of drift are from N.W. to
S.E., yet in those contiguous tracts which have been elevated in other
directions the course of the drift changes immediately with the varia-
tion of the strike. Thus on the exterior margin of the great coal-field
of S. Wales vast quantities of materials resulting from the breaking
up of the carboniferous series have been dispersed to the N.E., N., and
N. West, directions excentric from the broken margin of that elevated
tract.

In Pembrokeshire, again, where the prevalent lines of strike are
from E. to W., the drift has been carried southwards. Conceiving
that the great masses of these drifts have been formed at various pe-
riods under the sea, either in gulfs, estuaries, or straits, and have been
raised up at different periods when the solid strata were elevated,
the author then proceeds to consider the probable conditions of the
surface of this portion of the country for some time after such emer-
sion, and yet at a period comparatively remote. He instances many
flat embayed tracts which, from the equable surface of the sand and
gravel, are supposed to have been for some time under water, occu-
pying lakes which have been drained by the deepening of gorges is-
suing from these bays ; since it is shown that a very slight difference
of level in the beds of rivers at several gorges would effectually bar up
the present streams, and pond them back into lacustrine expanses,
Hence he infers that slight additional movements of the land, aided
by the excavating process of the rivers themselves, may have operated
in draining these flat tracts. A large part of Herefordshire watered
by the Wye is supposed to have been under such waters, which have
since escaped by the picturesque gorges of Ross and Chepstow. The
Vale of Radnor is a similar case ; now drained only by a feeble rivulet,
But the clearest examples of successive lacustrine expanses are ex-
hibited in the descent of the Teme; first in the tract still called
« Wigmore Lake ;” from whence the superabundant waters have
escaped through the upper Silurian rocks in the gorge of Downton
on the rock; and next in various expansions and contractions between
Ludlow andthe Abberley Hills, where they have been again barred up
by that ridge until the gorge at Knightwick Bridge was deepened,
opening out a channel for their escape into the great Valley of the
Severn. The finely levigated sand, marl, and mud, at small heights
above the present stream point to this anterior lacustrine condition.

568 Geological Society.

The period of the finai desiccation of these river-lakes, and the reduc-
tion of the rivers to their present channel, is supposed to have been
contemporaneous with that recent elevation which in raising the land
to greater heights brought up large adjacent portions of the bottom of
the sea, and to the consideration of which the second part of the me-
moir is devoted under the head of ‘ northern drift.”

In the region of Welsh and local drift attention is specially called
to the length of time during which existing causes have been in un-
disturbed action, as proved by the magnificent mass of Travertino
formed and still forming at the Southstone rock ; whilst he also points
to the discovery of shell marl in a bog near Montgomery, containing
several species of Lymnea, which has evidently been formed in the
manner described by Mr. Lyell in his memoir on the marl loch of
Forfarshire.

Northern Drift.—Detritus differing entirely from that which covers
Wales and Siluria, is spread over large parts of Lancashire, Cheshire,
and N. Shropshire, ranging up to the edges of the region above
mentioned. The materials of this drift consist of granites, porphyries,
and other hard rocks, which have been derived from the mountains of
Cumberland, a few perhaps from those of Scotland. The drift further
contains much sand and clay, with many pebbles of smaller size,
which varies exceedingly in different districts. Thus, in N. Salop,
near the great outlier of lias, described by the author*, fragments of
that formation are added to the mass, and as it advances to the south
the materials become still more varied ; the fragments, however, of
the northern granite and porphyries always existing to identify the
drift. Its distinguishing feature is the reoccurrence at intervals of
large blocks or boulders, of northern origin, a large proportion of
which lie at various heights on the slopes of the mountains skirting
the N. Welsh coal-field, and encumbering the northern flanks of the
Wrekin and of Haughmond Hill; while a few have been propelled to
the edge of the Silurian rocks south of Shrewsbury. They prevail in
vast quantities in the high inland district between Wolverhampton and
Bridgnorth, from which latitude they begin to diminish in size ; but
coarse gravel, composed of the same materials, is prolonged south-
wards like the tail of a delta through Worcestershire, until it dies
away in the fine silt and gravel of the Vale of Gloucester. Not a
fragment of any such detritus enters into the region of Welsh and Si-
lurian drift ; but in the environs of Shrewsbury certain mounds of the
latter are capped by clay and boulders of the northern drift, which
is thereby shown to be of subsequent formation. The best proof of the
recency of the epoch during which this northern drift was accumulated
is, that it contains sea shells of existing species. These were formerly
noticed at Preston, in Lancashire, by Mr. Gilhertson ; and by the
author at the height of 350 feet above the sea. In Cheshire they have
been observed by Sir P. Egerton at heights of about 70 feet+. Mr.
Trimmer has cited similar shells on Moel Tryfanet, now ascertained to
be 1392 feet above the sea, and has recently detected them near

* Proceedings of the Geological Society, Vol. IT. p. 114.
+ Ibid., Vol, Il. p- 189. t Ibid., Vol. I. p. 331.

Geological Society. 569

Shrewsbury. Mr.'Murchison has collected evidence of their diffusion
over a wide area in Shropshire, tracing them at intervals from Maring-
ton Green, N.W. of Shrewsbury, by the Wrekin and Wellington, to
the high grounds between Bridgnorth and Wolverhampton, at least
60 miles inland, and at heights varying from 300 to 600 feet. He has
also been enabled to add several species to those mentioned in any
former list. These shells having been examined by good conchologists
(including Dr. Beck, of Copenhagen,) prove to be identical with spe-
cies now inhabiting adjacent seas, viz. Buccinum reticulatum, B. un-
datum, Dentalium entalis (Linn.), Littorina littorea, Tellina soldula ?
Venus , Astarte ——, Cardium tuberculatum, C. edule, Cyprina
islandica, Turritella ungulina (Beck), (Turbo ungulinus, Linn.,) Donax
or Mactra.

It was a prevalent belief that large boulders were usually lodged
upon the surface of the gravel and sand; but cuts which have been
made through mounds of these materials at Norton, near Shrewsbury,
have proved that the larger blocks occur at considerable depths
below the surface mixed up with shells, sand, gravel, and clay. This
is the locality described by Mr. Trimmer* as indicating the exist-
ence of dry land anterior to the deposit of the shells and gravel, by
the occurrence of a peat bog, which he supposed to have been formed
out of the remains of a submerged forest ; the stumps of the trees of
which were said to be still rooted in their parent soil, and standing in
their growing posture. Having examined the spot (accompanied by
Dr. Du Gard), Mr. Murchison has obtained clear proofs that the sup-
posed trees were stakes with sharpened points which had been driven
down into a patch of subjacent clay; the other remains consisting of
a plank and smaller stakes which had been laid horizontally. This
woodwork formed the support of the old road, which in making the new
one had been cut down beneath the ancient foundations. The
patch of clay into which the piles were driven, lying in a depression
between two hillocks of gravel, must have given rise to a wet and
boggy spot, which having been rendered passable by piling and dam-
ming, the dry materials of the contiguous hillocks were doubtless
shovelled in to complete the road, thus giving rise to the deceptive
appearances of marine drift overlying the supposed forest.

Though the collocation of the boulders, sand, gravel, loam, clay, and
shells is in parts very irregular, yet the materials are sometimes finely
laminated: the whole, it is presumed, may have been thus brought
together at the bottom of a sea, as the mass is not unlike many raised
sea-beaches, with one of which, at the mouth of Carlingford Bay, Ire-
land, recently visited by Professor Sedgwick and himself, the author
compares it.

From the evidences afforded by these recent shells it is inferred, that
the tracts covered by them must have lain under the sea during the
modern period; whilst from the continuation of the granitic drift
from the high grounds east of Bridgnorth into the Vale of Worcester,
Mr. Murchison conceives that the sea must at the same time have
covered the Valley of the Severn from Bridgnorth to the Bristol

* Proceedings of the Geological Society, Vol. II. p, 200.

570 Geological Society.

Channel, thus separating Wales and Siluria on one side, from En-
gland on the other. Having shown that the Welsh and Silurian
mountains were partly raised at an earlier period, he points out the
Abberley and Malvern Hills, as constituting the western side of a
strait of the sea, the eastern shore of which was the Cotteswold Hills.
He deduces the principal proof of the preexistence of this eastern
coast from the observations of Mr. H. Strickland, which show the
transport from the east and north-east of fluviatile and land shells
mixed with the remains of extinct quadrupeds in banks of coarse
gravel, following the drainage of the Avon near to where that river
empties itself into the Severn; and he asserts, that the terrace-like
deposits of Cropthorne are exactly those which would have been ac-
cumulated at the mouth of a river, if the materials had been carried
onwards beneath the waters of the adjoining strait of the sea, illus-
trating his views by the analogies of other rivers and estuaries. He
therefore presumes that the deposit of Cropthorne may have been
coeval with that of the northern drift. After an explanation of the
theories hitherto proposed to account for the transport of large boul-
ders to distant points, the author states that the evidences in question
seem to him to be subversive of the diluvial hypothesis which imagines
that. the blocks were carried over the land, it being proved that here,
at least, they were accumulated under the sea. He does not think we
have yet been furnished with a full explanation of any method by
which such blocks can have been transported to distances of 100
miles: for supposing them to have been derived from the shores
of Cumberland, and that they extended in a delta from thence, it
would appear that assuming the slightest degree of inclination, viz.
3°,—which could give adequate momentum to the ordinary power of
running water acting upon these loose materials,—the southern part
of the delta (even at a distance of 50 miles from Cumberland, ) must,
as suggested by Mr. Lonsdale, have lain at the vast depth of i3,000
feet beneath the sea, in which case all Wales would have been equally
submerged ; though we have proof that the mountains of that country
had risen to acertain height previous to the accumulation of the
northern drift. It is further submitted that under the physical features
of the region when this drift was formed, i, e. when a great arm and
strait of the sea separated England from Wales, submarine currents
alone could not have been powerful enough to propel these large
blocks, though the question is one which ought to be more completely
disposed of by those versed in the laws of dynamics. Mr. Murchison
next takes into consideration the theory of the transport by ice. After
allusion to the views of Esmarck, De l’Arrivi¢re, Haussman, &c., it is
shown that Mr. Lyell has thrown great additional light on this subject
by his observations on Sweden and the Alps, by which it really ap-
pears that under certain limitations ‘ice floes” may have been “‘ vere
cause” in the transport of large blocks, depositing them under seas
and lakes at great distances from the source of their origin. In the
Salopian case, however, though it is possible such means may also
have been employed, there are many arguments which weaken the
application of the hypothesis, such as the rounded and worn exterior

Geological Society. 571

of the boulders, and their diminution in size and quantity from north
to south. It might also be contended that we have no right to infer
the existence of a colder climate in our latitudes in those days ; but this
objection does not appear unanswerable, since it might be replied,
that if at the period of the northern drift England, Ireland, and the
continent of Europe were united by a lofty chain of mountains, there
might have been a temperature sufficient to have formed annually
large bodies of ice on the shores of Cumberland. Passing however
from this difficult question of the method of transport, Mr. Murchison
states that the greatest of the anomalies hitherto presented by these
boulders is obviated, when we dispel from our minds the idea of their
having been carried over preexisting lands. Having once ascertained
that large distributions of them took place under the sea, the different
heights at which we now find them may, he supposes, be satisfactorily
accounted for, by movements of elevation and depression acting upon
the bed of the sea with unequal measures of intensity, raising up shells,
gravel, and boulders which were accumulated at the same period, to the
respective levels which they now occupy, doubtless producing many of
the cracks and fissures with which the solid strata are replete, and
leaving denuded valleys between the points so elevated.

Feb. 24.*—A paper was first read, entitled “‘ Observations on a
Patch of red and variegated Marls, containing Fossil Shells, at Colly-
hurst, near Manchester,” by J. Leigh, Esq., and E. W. Binney, Esq.,
and communicated by Roderick Impey Murchison, Esq., F.G.S.

Manchester stands on a slightly elevated platform of upper new
red sandstone ; but the country to the north-west, north, and east of
the town rises to a considerable height, and is traversed by the valleys
of the Irwell, the Irk, and the Medlock, which furnish the only natural
sections of, the district. The formations exhibited in these valleys, and
supposed to extend under Manchester, are, first and lowest, the car-
boniferous group; secondly, the lower red sandstone and marls ;
thirdly, the magnesian limestone ; fourthly, the lower red marl;
fifthly, the upper red sandstone; sixthly, the upper red marl; and
seventhly, the superficial detritus.

The principal object of the authors being to describe the upper red
marl, they notice briefly the characters of the other deposits.

The accumulations of superficial detritus are sometimes thirty feet
thick, capping nearly all the high ground, and extending over the val-
leys. In the lower part they consist of water-worn fragments of gra-
nite, greenstone, porphyry, claystone, mountain limestone, and coal
measures, imbedded in sand ; and in the upper, of stiff blue clay,
containing partially rounded fragments of the same rocks but of
greater size. Portions of the lower red sandstone and marl are some-
times found, but none of the magnesian limestone. Blocks of granite,
weighing two or three tons, occuron the summit of some of the hills
which surround the Irwell and the Irk,

The lower red sandstone, the magnesian limestone, and lower red
marl are exposed at Worsley Mills and at Stockport, dipping conform-

* The Anniversary Proceedings of Feb. 19, will be found at p. 310, in
our Number for April.

572 Geological Society.

ably with the coal measures ; but at the latter locality they are stated
to be overlaid unconformably by the upper new red sandstone,

The immediate vicinity of Manchester consists of upper new red
sandstone, occupying the cavity formed by a flexure in the underlying
deposits, and is generally supposed to be unconformable to them. It
is very soft when first exposed, but hardens by exposure to the atmo-
sphere ; and is occasionally marked by belts and nodules of white
sand, and in the lower part contains rounded fragments of granite,
quartz, and other older rocks. No organic remains have been no-
ticed in it.

The upper red marl is exposed only at Collyhurst, about a mile to
the north-east of the Manchester Exchange, in the old road to Blake-
ley; but it has there yielded a greater number of fossils than has been
found in any other bed of the superior divisions of the new red sand-
stone group in England.

The deposit extends about a hundred yards, and at one of the
points examined presented the following details :

Top a. Variegated marls, no organic remains .... 6 inches.
b. Strong, red marl, traversed near its centre
by a thin layer of fragile bivalve shells... 5 ——
c. Light-coloured, calcareous marl, marked
with lines and spots of a beautiful red... 3 ——
d. Light-coloured, calcareous, strong marl,
containing an immense number of imper-
fect casts of bivalves and perfect univalves 5 ——
When the marl is first excavated it crumbles
under the touch, but after exposure for a
short time, it is fractured with difficulty.
e. Clay, striped red and white, and containing
GADts OF Dayal Ves igi Gh Litera aes teste ar- Cac's 4——
f. Light-coloured marl, similar to No. 4, and
inclosing numerous casts of bivalves and

LINIVALVES: w1oik)e ie -lole lsteteieedoks canucteels 3 —
g. Variegated marl, with an immense number
of univalves and bivalves, 2 inches ..... 2—

h. Indurated red marl, mottled with streaks of a
greenish colour. The upper part contains
numerous casts of large bivalves, and the
light-coloured streaks also inclose casts
of bivalves and univalves. Few shells are
found below the depth of one foot, though
the author had the bed penetrated to the
depth of 29 feet, when an influx of water
prevented them from boring any further.
The rhomboidal fracture, so characteristic
of the red marl, was very observable in
this ibedo: stool te isteloRre > wttietnie te -. 29 feet.

With respect to the geological position of these fossiliferous marls,
the authors are fully satisfied that the deposit reposes on the upper

Geological Society. 573

new red sandstone by which the marls are surrounded, though, from
the covered nature of the ground, the connexion of the two forma-
tions cannot be ascertained. In mineral aspect the lowest beds at
Collyhurst are said to agree with the upper red marl of Lincolnshire
and Cheshire, and to be distinguished from it only by the presence
of fossils and the absence of salt ; while the Collyhurst strata differ
from the lower red marl, in colour, fracture, and the organic remains.

In accounting for the presence of these fossiliferous marls in the
situation described, and their absence from the top of the new red
sandstone in the immediate neighbourhood, the authors suppose that
the marls were deposited in a hollow of the new red sandstone, and to
have been, therefore, protected from denudation.

A notice, by Francis Offley Martin, Esq., inclosing communications
from Col. Brown and Lieut. Laurence, of the Rifle Brigade, and Mr.
Stevens, on the streams of sea water which flow into the land in the
island of Cephalonia, was next read.

These communications were procured by Mr. Martin at. the request
of Mr. Lyell.

Lieut. Laurence’s letter is dated 31st of May, 1835, and contains
an extract from an account sent to him by Mr. Stevens of the na-
ture, excayation, and the operation of the stream. The length of
the channel made for conducting the water was 20 yards and its
width 3 feet ; and at the end of the channel a pit was made nearl
100 square yards in extent, and to the depth of about 4 feet below
the level of the sea. On opening the sluice a stream of 150 square
inches rushes into the pit with a velocity of 20 feet a second, and
down a channel in the form of a segment of 4th of a circle of 18 feet
diameter. A constant discharge of this stream raises the water in
the pit to within 2 feet of the top of the arched channel. The stream
escapes through the fissures in the pit, but the direction which it
afterwards takes has not been well ascertained, though shafts have
been sunk for that purpose. In these shafts water of the same de-
scription with that in the pit is found, rising and falling in the same
manner. Mr. Laurence also states that when the sluice-gate is shut
down after a very considerable discharge of sea water into the pit,
the water in the pit falls a few inches lower than it was previously to
the discharge ; but is afterwards raised to the usual level by the
freshwater springs.

Mr. Stevens’s letter, dated the 28th August, 1835, gave an account
of the making of the excavation, and states that the experience of a
year and a half had proved that the stream is not liable to any perio-
dical change.

Col. Brown’s communication bears date the 27th of August, 1835,
and gives an account of the physical features of the island, the nature
of the excavation, and the probable manner by which the subterra-
nean current is disposed of.

On the eastern side of the harbour of Argostoli the country rises
abruptly from the shore to a considerable elevation, and then more
gradually until it is lost in one of the great ridges which intersect
the island; but on the western side the narrow peninsular ridge at

574 Geological Society.

the foot of which Argostoli is built, nowhere exceeds 400 feet in
height, sloping gradually towards the sea, and is surrounded by com-
paratively shallow water. The whole of the ridge consists apparently
of coarse limestone, presenting on the surface large, detached blocks.
Col. Brown’s account of the excavation agrees with those already
given. He notices the springs of fresh water, and the fact, that when
the sluice is first shut the pool is drained to a much lower level than
that at which it afterwards stands, and this phenomenon he conceives
may be explained on the principle of natural siphons.

He says that there are three other openings on opposite sides of
the promontory, through which sea-water flows into the land, and he
is of opinion that there may be many more.

With respect to the question what becomes of the water, Col. Brown
has always believed that the streams are conducted to subterranean
fires, and that the earthquakes so common in the island are caused
by the expansion of the gases generated by the action of those fires
on the sea water.

A notice accompanying rock specimens from the caves of Bally-
bunian, on the coast of Kerry, by Lieut. Col. W. H. Sykes, F.G.S.,
was then read.

The author states that his principal object in bringing this commu-
nication before the Society is to induce geologists to examine a part
of Ireland seldom visited, but which he conceives to be highly deserv-
ing of attention.

The coast of Kerry, in the neighbourhood of Ballybunion, presents
a series of cliffs varying from 100 to 150 feet in height, and is in-
dented by numerous bays. The stratification consists of several feet
of debris, composed of angular fragments of silicious rocks and earth ;
a bed of alum shale follows, breaking into rhombs; then a stratum
of lignite or carbonaceous schist, and another of iron shale. These
strata are occasionally repeated, and said, on the authority of Mr.
Ainsworth, to rest on limestone.

A principal feature in these beds is a disposition to separate into
rhombs; and the clifls in several places present the solid angles pro-
jecting beyond the vertical line of the cliffs, while the roof of some
of the caves is groined like the intersection of Gothic arches. The
general inclination of the strata is about 13° to the east, but it
is frequently altered by faults, and sometimes presents anticlinal
dips.

‘Or the exact age of the beds the author offers no opinion, but he
thinks that it is not posterior to the carboniferous series.

Among the specimens which accompanied the memoir were some
from the west end of the Isle of Innisfallen, in the Lake of Killarney.
The strata at that point consist of narrow vertical and alternating
ridges of asilicious rock and limestone : the former projecting beyond
the surface of the latter.

A paper was last read, entitled, “ An Account of some fossil vege-
table Remains found in the sandstone which underlies the lowest bed
of the carboniferous Limestone, near Ballisadiere, in the County of
Sligo, Ireland,” by Sir Alexander Crichton, M.D., F.GS., &c.

Geological Society. 575

In the county of Sligo there are no coal deposits, the nearest being
the Arigna coal-field, in the county of Leitrim. The bed of sand-
stone containing the plants is well exhibited, resting upon gneiss, with
which it is stated to dip conformably, and is covered by the mountain
limestone. The state of the plants prevented the author from ascer-
taining their generic characters, but the specimens consist principally
of flattened stems covered occasionally with a thin coating of carbo-
naceous matter. The lowest beds of limestone in this part of Ireland
abound with corals, and contain nodules of chert; while the upper
contain many shells, and are purer and better adapted for forming
quicklime. The author then remarks on the great interval which
must have taken place between the growth of the plants contained
in the sandstone, which underlies the limestone, and of those which
occur in the coal-measures resting upon it.

March 9.—A paper was read, “ On the Remains of Mammalia
found in the Sewalik Mountains, at the southern foot of the Hima-
layas between the Sutluj and the Ganges,” by Capt. Cautley, F.G.S.,
and communicated by J. F. Royle, Esq., F.G.S. ‘

The range of mountains from which the remains described in this
paper were obtained, extends from the Sutlej to the Burhampooter
and the district of Cooch Behar. Its general direction near the Sutluj
is N.W. and S.E., but on approaching the Burhampooter it is many
points nearer direct E. and W. It is either connected with theHima-
layas by a succession of low mountains, or is separated from them by
valleys varying in breadth from three to ten miles, the principal being
the Deyra valley, between the Ganges and the Jumna, and theKearda
and the Pinjore, between the Jumna and the Sutluj. The breadth of
the range is from six to eight miles ; and the loftiest peaks do not
exceed 3000 feet, the average height being from 2000 to 2500
above the level of the sea, or from 500 to 1000 above that of the
adjacent plains. The only roads by which the range can be passed
follow the line of the rivers which flow through gorges flanked by pre-
cipitous cliffs, sometimes crowned by inaccessible pinnacles, on the
top of which is usually a solitary fir-tree. As the range is not
known to the present inhabitants or to geographers by a distinct name,
Capt. Cautley has been induced to call it the Sewalik, a term by
which the portion between the Jumna and the Ganges was formerly
known*; and he states that he is anxious to give to it a distinct ap-
pellation to avoid the use of the indefinite terms Lower Hills and Sub-
Himalayas.

The formation of which the range is composed between the Sutluj
and the Ganges, the portion personally examined by the author, con-
sists of alternating beds of conglomerate, sandstone, marl, and clay,
inclined at angles varying from 15° to 35°. The succession of the
beds is irregular, the marl prevailing to the west and the conglomerate
to the east of the Jumna.

* Smith’s Exotic Botany, vol. i. p.9. Dow's History of India. The
name is also used in some writings in the possession of the high priest re-
siding at Deyra. The word is a corruption of Shibwalla, from the district
between the Ganges and the Jumna having been the residence of Shib.

576 Geological Society.

The beds of conglomerate, or in the language of the author, of
shingle, are of enormous thickness, and are composed of pebbles of
granite, gneiss, mica-slate, hornblende-slate, and trap, derived appa-
rently from the Himalayas, and are either loosely aggregated or ce-
mented by clay and carbonate of lime.

The sandstone consists of grains of quartz and scales of mica, ce-
mented by oxide of iron or carbonate of lime. The colour presents
various shades of red and grey ; and the state of induration differs in
proportion to the quantity of the cementing matter, which sometimes
gives the stone a crystalline appearance. It is occasionally used as
a building material and in some instances has resisted for a long time
the action of the atmosphere. Carbonaceous matter is of common
occurrence in the sandstone, either in fragments exhibiting the struc-
ture of dicotyledonous plants, or as grains disseminated throughout
the stone in nearly equal proportions with the sand. Carbonaceous
matter exists also in the marl, and in one instance Capt. Cautley
noticed it in the conglomerate. It has never yet been found in suf-
ficient quantity to be of economical importance. At the Kalowala
Pass, one of the entrances into the Deyra valley, the author discovered
in a bed of yellow and red sand elliptical masses of sandstone coated
by a thin layer of carbonaceous matter.

The marl or clay conglomerate is described as consisting of frag-
ments of indurated clay cemented by clay, sand, and carbonate of
lime. It is exceedingly tough, and is less easily acted upon by run-
ning water than the other strata.

The only point at which trap has been observed is in the neigh-
bourhood of Nahun, where it has been noticed by Dr. Falconer.

Soda effloresces on the surface of the shingle and sandstone, and
selenite occurs occasionally in the clay.

The distribution of the organic remains in the district between the
Jumna and the Ganges, Capt. Cautley states to be as follows, the
greater part of the fossils having been obtained at the Kalowala Pass.

Conglomerate or Shingle Beds.—Lignite, scarce.
Sandstone.—Trunks of dicotyledonous trees in great abundance,
lignite, and remains of reptiles.
Marl.—Pachydermata : teeth, and remains of a species of Anthra-
cotherium.
Carnivora: genera doubtful, but some of the teeth corre-
spond with those of the Bear.
Rodentia: Rat, and a small variety of Castor.
Ruminantia : Deer, more species than one.
Solipede, teeth of a Horse.
Gavial and Crocodile, teeth and bones in abundance.
Emys and Trionyx, fragments of.
Pisces, vertebre and perhaps scales.
Shells, freshwater genera.

The district between the Jumna and the Sutluj consists of the same
series of shingle or conglomerate, sand, clay, and marl; but the shin-
gle is less abundant, and differs in being composed of pebbles of va-

Geological Society. 577

rious kinds of clayslate and quartz, and the marl is exposed only at
Nahun, where it contains the same organic remains as in the Kalowala
Pass. From Nahun to the plains there is a succession of sandstones
and clays, dipping on an average about 20° tothe north. In the
neighbourhood of that town the sandstone is hard and used for build-
ing; but it becomes soft on approaching the plains. The clays are
stated to be more or less rich in Testacea, and the sandstone in re-
mains of Mammalia.

The large collections of bones obtained by Capt. Cautley were found
partly lying on the slopes among the ruins of fallen cliffs, and partly
in situ in the sandstone; and he is of opinion that the former have
been, in a great measure, preserved by the sandstones in immediate
contact with the bones, being much harder and more ferruginous than
in the general mass.

The following is a list of the remains which had been determined
at the time the memoir was written.

Mastodon, elephant, rhinoceros, hippopotamus, hog, horse, Ox,
elk, deer, several varieties ; carnivora, canine and feline ; crocodile,
gavial, emys, trionyx, and fishes ; and portions of undescribed mam-
malia.

The remains of all these animals are in great abundance, with the
exception of the Horse and Carnivora ; but the bones of the head are
better preserved than those of the trunk or the extremities. Some-
times the fractured bones have admitted of being joined, though the
surfaces were coated with calcareous spar.

In assigning an age to the formation composing the Sewalik moun-
tains, Capt. Cautley adopts the views of his friend Dr. Falconer, who:
in a notice read before the Asiatic Society of Calcutta, considered the
deposit to be synchronous with that from which Mr. Crawfurd
obtained the remains near Prome, on the banks of the Irawadi,
there being an agreement in the organic remains. The author then
offers some remarks on the Mastodon elephantoides and M. latidens,
and in consequence of his having found jaws in which the front teeth
are not to be distinguished from the teeth of M. latidens, and the rear
from the teeth of M. elephantoides, he conceives that the distinc-
tion established on detached teeth will be found to be erroneous.

March 23.—A paper was first read, entitled, “ A Description of
various Fossil Remains of three distinct Saurian animals discovered
in the autumn of 1834, in the Magnesian Conglomerate on Durdham
Down, near Bristol.” By Henry Riley, M.D. and Mr. Samuel
Stutchbury; and communicated by Charles Lyell, Esq., P.G.S.

The conglomerate in which these Saurian remains were discovered
rests upon the edge of inclined strataof mountain limestone, filling
up the irregularities of their surface, and consists of angular fragments
of the limestone cemented by a dolomitic paste. The thickness of
the deposit at the point where the remains were discovered does not
exceed twenty feet.

Of the three animals described in the paper, two belong to a genus
for which the author proposes the name of Paleosaurus, and the third
to one which they have called Thecodontosaurus.

Third Series. Vol. 8. No. 50, Supplement, June 1836. 31L

578 Geological Society.

The characters of the genus Paleosaurus are derived from the
teeth, which are described as being carinated laterally, and finely ser-
rated at right angles to the axis. They are stated to differ from those
of all the Saurians known to the authors: and as the teeth in
their possession exhibit minor marked characters, they are induced to
consider that they belonged te two species, which they have named
P. cylindricum and P., Platyodon.

The genus Thecodontosaurus is likewise founded on the struc-
ture of the teeth, and their having been deposited in distinct alveoli.
Among other remains in the Museum of the Bristol Institution is
the right ramus of a lower jaw, 34 inches long and 14 in the greatest
depth, from the summits of the teeth to the under rise, consisting
of the dental bone, containing 21 teeth, with portions of the sub-
angular and complementary bones, and perhaps traces of the oper-
cula. The alveolar groove for the reception of the teeth is formed by
two ridges of nearly equal height, the teeth being deposited in it, in
distinct alveoli, to nearly half theirlength. The teeth somewhat re-
semble in shape a surgeon’s abscess-lancet, being acutely pointed and
flattened ; while the anterior edge is also curved, but concave and
strongly serrated, the serrature being directed towards the apex of
the tooth. The middle teeth are the largest, rising not less than a
quarter of an inch above the socket. They all possess a conical hol-
low, and in a specimen belonging to the Rev. D. Williams a young
tooth is well exhibited in one of the alveolar cavities. From these cha-
racters the authors infer that the jaw belonged to a Saurian, but not
to the great genus Lacerta of Linnzus as reformed by Cuvier by re-
jecting the Crocodiles and Salamanders. They further infer from the
shape and serrated edge of the teeth that it did not belong to the
Crocodiles ; nor to the Lizards, whose alveolar inner edge is either
wanting or much less elevated than the outer. They also show that
it was not allied to the Monitors, because of the elevated inner alveolar
edge, the distinct alveoli, the teeth remaining hollow and the
formation of the new tooth in the same cell with the old one, as well
as from the great number of the teeth. With respect to the Iguanas

_ and Scinks they show that the fossil could not have belonged to them,
in consequence of the distinct alveoli, the inner alveolar edge, and the
form of the summit and serratures of the teeth: and that it differed
from the Saurodon in having a ridge on the outside of the tooth with
the edge crenated and of unequal length.

Numerous other bones have been discovered, but as none of them
were found in connexion with teeth, the authors hesitate to assign
them to either of the genera which they have established. Among
these remains the following are described :

Vertebre possessing the peculiar characters, of having the centre of
the body diminished one half in its transverse and vertical diameters
so as to resemble an hour-glass; of a suture connecting the annular
vart or body with the processes ; and in the extremities of the ver-
tebra being deeply concave. These characters the author conceives
distinguish the fossil vertebre from those of all recent Saurians.

A nearly perfect chevron bone; ribs, one flat and imperfect, the

Geological Society. 579

other round with a double head and a deep intercostal groove ; a cla-
vicle ; portions of coracoids; a humerus, the articulatory extremities
of which expand to nearly three times the diameter of the centre of
the bone ; a humerus 7 inches long, 2 inches broad at the superior
extremity, and 14 at its inferior ; two femurs, one nearly perfect,
being 10 inches in length; part of an ischium; a tibia; a fibula;
metacarpal or metatarsal bones, with penultimate and ungueal pha-
langes.

In conclusion the authors state that these remains afford further
proof of the truth that the more ancient the strata the more the ani-
mal remains differ from existing types.

A memoir was afterwards read, “ On the Ossiferous Cavern of
Yealm Bridge, 6 miles south-east from Plymouth.” By Capt. Mudge,
Royal Engineers, F.G.S., F.R.S., &e.

This cavern is situated in a mass of limestone adjoining the village
of Yealmpton, near Yealm Bridge, and on the south side of the river.
It has been long known, and though large quantities of the bones
have been burnt in the limekiln, yet it was not till lately that its con-
tents attracted the attention of the scientific observer. Mr. Bellamy,
of Yealmpton, first detected their value, and Capt. Mudge in a visit
to Devonshire in the autumn of last year collected the information
detailed in the memoir, ‘‘ There were originally three openings into
the cave, each about 12 feet above the river Yealm, and a few yards
distant from each other. Large portions of the rock being removed
for economical purposes, a considerable part of the cavern has been
destroyed, and at the time of Capt. Mudge’s visit portions of only the
eastern and western chambers remained. The former consisted of a
descending shaft to the depth of 10 feet, which turned at right angles
and again ascended to the surface, both the descent and the ascent
being at an angle of 45°. Of the western cavern, a portion remained
uninjured. From the present opening it takes a northerly direction
for 43 feet, the height varying from 5 to 6 feet, and the breadth from
4to 5. It then turns westerly for 25 feet, the height varying from
5 to 12 feet, and the breadth from 31. to 5. The cave contained five,
distinct, sedimentary deposits, and where they did not fill it to the
roof the uppermost bed was covered by a layer of stalagmite. The
order of the deposits was as follows :

Top. Loam, containing bones and stones .......- 31 feet.
Stiff whitish clay .... 22... ee eee eee e ee 24
PN Sete: 55 cissegings petue pt. ley sou
Hed tgs on ste Ro naBy pilnieti’ 3+
Argillaceous sand .... 2.0. .2-2enn-ee vere 6 to 18.

Animal remains have been found only in the uppermost bed, and the
author, on the authority of Mr. Clift and Mr.Owen, states that they be-
long to the elephant, rhinoceros, horse, ox, sheep, hyena, dog,
wolf, fox, bear, hare, water-rat, and a bird of considerable size. Co-
prolites also occur in the same bed. Many of the bones are splin-
tered, chipped, and gnawed. Of the elephant only two teeth of a
young animal have been preserved, and the remains of the rhinoceros
are also rare, being confined to teeth and a doubtful bone, but those

3L2

580 Linnean Society.

of the hyzna, particularly teeth, exceed in quantity all the bones of
the other animals. Teeth and bones of the horse and ox are very
abundant, but the remains of the bear are confined to teeth. It
is however stated by the author that it is impossible now to determine
what proportions the animals originally bore toeach other. The peb-
bles found in the same bed with the bones are apparently derived
from the confines of Dartmoor, and differ from those contained in the
bed of the Yealm. In one part, where the roof is a little lower than
usual, the limestone is beautifully polished, as if by the friction of the
animals which inhabited the cave.

There are many other caverns in the neighbourhood, but the one
next in importance to that at Yealm Bridge is in the grounds at
Ketley. The floor of this cavern rises but little above the present
level of the river, and consists of gravel and pebbles corresponding
with those in the bed of the Yealm. It has been ascertained that it
does not contain bones, and Capt. Mudge therefore concludes that
the caverns of Yealm Bridge and Ketley were exposed to very dif-
ferent conditions when the elephant and the hyena inhabited the
southern part of Devonshire. As far as regards space the accommo-
dation in Ketley Cavern was much superior to that of Yealm Bridge
Cave, and consequently it may be inferred that at the time when the
hyenas inhabited the latter, they were prevented from entering the
former either from its having been frequently flooded or permanently
under water. ——-

LINNEAN SOCIETY.

May 24, 1836.—At the Anniversary Meeting held this day, His
Grace the Duke of Somerset in the chair, previous to the usual
business the Secretary, Dr. Boott, stated that the Society had lost by
death during the past year the following 11 Fellows and 2 Associates,
viz,

Fellows —G. T. Burnett, Prof. of Botany in King’s College;
A. Crouch, Esq.; George Harry, Baron Grey of Groby ; D. Hosack,
Esq., M.D., F.R.S. ; E. Jennings, Esq.; J. Macculloch, Esq., M.D.,
F.R.S.; Mr. Wm. Malcolm; H. Phillips, Esq.; H. Sim, Esq. ;
W. Smith, Esq., F.R.S.; Rev. G. A. Thursby, M.A., F.R.S.

Associates.—Mr. T. Drummond ; Rev. J. T. Thomson.

The Secretary then particularized, in the following terms, some
of the deceased members :

« Dr. Hosack, without attaining to or claiming any eminence as a
botanist, was one of theearlier promoters of that science in America,
and formeda botanic garden in theneighbourhood of New York, which
was eventually purchased by the State or by one of the colleges
of that city; and he undoubtedly would have anticipated many of
the discoveries of later observers, had not his attention been neces-
sarily drawn to medicine, from the distinguished reputation which
he acquired as a physician. He visited Europe at an early period
of life, and made the acquaintance of the more distinguished men of
science in this country and in France ; and the grateful recollection
he ever cherished of the reception he met with in Europe prompted
that liberal hospitality to strangers for which he was always honour-

Linnean Society. 581

ably distinguished. He was a generous patron of science and art;
and one of those who stood prominently forward in giving that
grateful reception to the distinguished leaders in one of the Arctic
expeditions. It may be remembered that Sir J. Franklin and Dr.
Richardson, and, I believe, Capt. Back, were hailed on their arrival at
New York by the mayor and principal citizens of the city, and that
they were conveyed to the confines of Canada free of expense,
cheered by the sympathies of all around them,—one of those evi-
dences which the heart affords of the cordiality and respect existing
between America and England, whatever some writers may say of
the contrary. Dr. Hosack published the life of his friend Gen.
Clinton, and was the author of various papers on the medical and
other branches of science.

«I feel that this is not the place for doing full justice to the me-
mory of Mr. Smith, for I am not aware that he particularly directed
his attention to any branch of natural history ; but as the early, stre-
nuous, and constant advocate of civil and religious liberty he is en-
titled to the respect and admiration of all those who believe in the
capacities of human nature for a progressive advancement in intel-
lectual and moral power. It is well known that Mr. Smith was re-
turned M.P. for Sudbury and Norwich for nearly half a century, and
that towards the close of the last century, and up to a compara-
tively late period of his life, he was one of what originally was com-
paratively a small band, who, when liberal sentiments were obnoxious
to a degree which I believe it to be impossible for us at the present
time to conceive of, pleaded for the rights of humanity, when those
rights were denied not only to the enslaved African, but to a large
portion of the people of this country, especially to the conscientious
Dissenter, who was at one time looked upon as hardly a loyal subject
of therealm. To those who, in watching the changes which human
institutions undergo in the progress of time, are convinced that a
chastened and enlightened spirit of liberty, as it has become more
and more developed, has in all times given additional dignity to hu-
man nature, by enabling it to put forth those inherent energies, all-
instructive of good, which, like the branches of the oak, acquire a
hardy vigour and nobler growth as they are free to extend themselves
in the liberal light and air of heaven,—to such an observer of the
eventful period of the last half-century the name of Mr. Smith must
often recur as one of the most unquestionable benefactors of man-
kind. If not distinguished by any of the splendour of genius, or as
standing prominently forward in the first ranks of public life, he was
more honourably distinguished by the inflexible integrity of his
character, the uniform liberality and consistency of his opinions,
and the unobtrusive virtues of his private life,—characteristics which,
if they failto give the widest and loudest development of fame, are
yet sure of the truest and most lasting. Mr. Smith attained to an
advanced period of life, and survived to see many of the great and
benevolent objects which he advocated finally accomplished ; and
I should say, that of the larger award of charity and justice which
has been rendered to the Dissenters of this country, of which
Mr. Smith was one, nota little of it may be said to have been owing

582 Linnean Society.

to the evidence which his own life afforded of the peaceable disposi-
tion, the unquestionable loyalty, the intelligence and high moral worth
which belong to that large portion of the people of England.

« In the death of Mr. Drummond we have to lament the loss of
a very useful man ; one to whom we have been indebted for many
years for many rare plants which he collected in the Rocky Moun-
tains during his first expedition to North America, and in the
valley of the Mississippi in his last visit to that continent. He was
sent out principally through the} instrumentality of Sir William J.
Hooker, for the purpose of making collections in all the depart-
ments of natural history ; and thereare some present who know how
well he accomplished the objects of his mission. His plants were
purchased by several naturalists in this country, in France, and
America; and I understand from Sir W. Hooker that indepen-
dent of the sums he had successively paid towards the expenses of
Mr. D.in America, and towards the support of his family in Scotland,
there is a considerable balance due to his widow. Mr. Drummond
died of fever last year at the Havannah; and I feel that his death
is scarcely less disastrous than that of Mr. Douglas.

« It does not seem to be sufficiently known that the natives of the
colder regions inevitably run great hazard of sickness and death
in resorting to climes of a high mean temperature. When it is
recollected what a remarkable exemption from mortality has uni-
formly characterized the arctic expeditions under Sir J. Ross,
Sir E. Parry, Sir J. Franklin, and Captain Back, and what a
frightful destruction of life followed the naval and military expe-
ditions to the West Indies in the war of 1793, and how many ex-
cellent men have successively perished in the fatal attempt to ex-
plore Africa, it is an irresistible conclusion that a high mean tem-
perature is most prejudicial to the health of those unaccustomed
to its influence: and the fact, I believe, is satisfactorily explained
by the more prolific sources of disease which may reasonably
be supposed to exist in the teeming climes of the south, and the
effect which a sudden change of temperature exerts on the hu-
man body. When we reflect, for instance, that in this country the
mean temperature is about 52°, and that we consequently have a
vital energy equivalent to the production of 46° of animal heat to
enable us to maintain the blood at its standard heat of 96°; and
that a native of Great Britain, by resorting to a clime where the
mean temperature is 75° or 80°, cannot accommodate himself at
once to this great change of circumstances,—that is, with a power to
generate 46°, he cannot at once lose this power, and generate only
21° or 16°, to put himself on a level with the condition of the native
of a tropical clime,—it will be evident that if he falls under the influ-
ence of the causes of fever, the disease must have in him a violenceand
a precipitancy highly dangerousto life. I believe this fully explains
the nature and fatality of what is called yellow fever ; a disease en-
tirely unknown té the natives of the West Indies and the most south-
ern states of North America. Dr. Ramsey of Charleston, South Ca-
rolina, shows for a long series of years that the deaths by yellow fever
in that city have been confined exclusively to strangers, and that no

Intelligence and Miscellaneous Articles. 583

native physician or nurse was ever known to contract the disease.
This liability to a fatal form of fever should at least induce great
caution in those who resort to hot climates ; and had the principle
on which the mortality in those climates depends been fully under-
stood, we might for many years perhaps have reaped advantages
from the labours of Mr. Drummond in the cause of science. We
owe to him many interesting plants; and like his fellow-labourer
Mr. Douglas, his name must ever be honourably associated with
the botany of North America.”

His Grace the Duke of Somerset was re-elected President ;
E. Forster, Esq., Treasurer; Francis Boott, M.D., Secretary; and
Richard Taylor, Esq., Under-Secretary; and the following five
gentlemen were elected into the Council, in the room of others
going out, agreeably to the By-Laws: viz. William Borrer, Esq.;
John Bostock, M.D.; John George Children, Esq.; Archibald
Menzies, Esq.; Rev. Thomas Rackett, M.A.

XCIV. Intelligence and Miscellaneous Articles.

ON THE PROPERTIES OF LIQUID CARBONIC ACID.

CCORDING to M. Thilorier, this liquefied gas presents the
strange and paradoxical fact of a liquid more expansible than the
gases themselves: from 32° to 86° Fahr., its volume increases from
20 to 29, that is to say, that at 86° Fahr. the increase of volume is
nearly equal to half the volume at 32° Fahr. Its expansion is four
times greater than that of atmospheric air, which from 32° to 86°
Fahr. only expands .3,°-, whilst the expansion of liquid carbonic acid
on the same scale is 334. If the temperature of a tube containing a
portion of liquid carbonic acid is raised, this liquid boils, and the
empty space above the liquid is saturated with a greater or less
quantity of vapour according to the elevation of the temperature.
At 86° Fahr., the quantity of liquid at 32° Fahr. sufficient to saturate
the empty space is represented by a portion of liquid equal to one
third of the space in which the vaporisation has been effected. At
32° Fahr. the portion of liquid of saturation is only », of the space
saturated.

The pressure of the vapour formed by the liquefied gas from 32°
to 86° Fahr., amounts from 36 to 73 atmospheres, which is equivalent
to an increase of one atmosphere for every centigradedegree. It is
important to observe that the weight or the density of the vapour
increases in a much greater proportion than the pressure, and that
the law of Mariotte is no longer applicable within the limits of the
liquefaction. If the density of the vapour is taken for the base of the
pressure, the pressure at 86° Fahr. will be equal to 130 atmospheres,
whilst the manoscope will only indicate 73 atmospheres. If a tube
of glass containing a portion of liquid anda portion of gas be heated,
two contrary effects will take place:

Ist, the liquid will augment by expansion ;

2nd, the liquid will diminish by vaporisation.

The thermoscopic effects are very different according as the por-

584 Intelligence and Miscellaneous Articles.

tion of liquid is greater or smaller to the portion of gas; the liquid
in the tube will either expand, contract, or remain stationary.
These anomalies furnished the means of verifying the numbers which
the preceding researches had given on the expansion and vaporisa-
tion. According to these numbers, the points of equilibrium above
which the liquid increases and below which it diminishes on the
addition of heat, result from such a proportion when empty or ful]
that at zero the liquid occupies 4-3 of the wholetube. If the liquid
at 32° Fahr. occupies one third of the tube it seems as a retrograde
thermometer, of which the liquid increases by cold, and diminishes
by heat. If the liquid at 32° Fahr. occupies two thirds of the tube
it acts as a regular thermometer ; that is to say, the liquid increases
and diminishes according to the laws of expansion. This thermo-
meter is limited to 86° Fahr. as at this temperature the tube is en-
tirely filled by the liquid.

The specific gravity of this liquefied gas at 32° is 0-83, water
being 1. It presents the singular phenomenon of a liquid which
from — 68° to +86° Fahr., runs through the scale of densities
from 0-90 to 0°60. It is insoluble in water, with which it does not
mix ; but is soluble in alcohol, ether, naphtha, oil of turpentine, and
sulphuret of carbon, in every proportion ; it is decomposed in the
cold with effervescence by potassium; it does not act sensibly on
lead, tin, iron, copper, &c.

When a jet of liquid carbonic acid is directed upon the bulb of
an alcohol thermometer, it falls rapidly to — 194° Fahr.; but the
frigorific effects do not correspond with this decrease of tempera-
ture, which is accounted for by the almost absolute want of con-
ducting power, and the little capacity for heat of the gases; there-
fore the intensity of the cold is enormous, but the sphere of action
is limited in some measure to the point of contact. If the gases
have little effect in the production of cold, such is not the case with
the vapours, of which the conducting power and the capacity for
heat are much greater. If zther, for instance, could be placed in
the same conditions of expansion as the liquefied gas, a much greater
frigorific effect would be obtained than by liquefied carbonic acid.
To accomplish this object it is necessary to render zther explosive,
which is easily effected by mixing ether with liquid carbonic acid.
In this intimate combination of two liquids which dissolve one an-
other in every proportion, the zther ceases to be a liquid perma-
nent under the pressure of the atmosphere ; it becomes expansive
similar to a liquefied gas, at the same time preserving its properties
as a vapour, that is to say, its conductibility and capacity for
caloric.

The effects produced by a tube filled with explosible zther are
remarkable; a few seconds were sufficient to congeal 772 grains
of mercury in a glass vessel. On exposing the finger to the jet which
escapes, the sensation is intolerable, and seems to extend much
further than the point of contact.

M. Thilorier intends to replace «ther by sulphuret of carbon;
and it is probable the effects obtained will be still more powerful.

Annales de Chimie, Dec. 1835.

Intelligence and Miscellaneous Articles. 585

AMALGAMATION OF ZINC PLATES.

In consequence of the great advantages pointed out by Mr. Fa-
raday of employing amalgamated zinc plates in the voltaic pile, M.
Masson recommends the tollowing simple and rapid method. After
having placed on the zinc a little mercury, dilute sulphuric acid
is poured upon it; the mercury is then rubbed over the surface of
the zinc by means ofa piece of linen. The mercury spreads over
the surface with great facility, and the amalgamation is very rapid:
a small quantity of dilute acid should be added from time to time;
this appears to act as a cleanser to the zinc, for in forming a vol-
taic circuit with only one element, the operation does not go on so
well or so quickly.— Annales de Chimie, November 1835.

CRYSTALLIZED OXICHLORIDE OF ANTIMONY.

M. Malaguti observes that when a large quantity of water is added
to a solution of protochloride of antimony, there isimmediately formed
a very white and bulky precipitate, and which, thrown upon a filter
and washed, constitutes the powder of algaroth. This, according to
Grouvelle, is composed of 2 atoms of protoxide and | atom of pro-
tochloride of antimony. If, instead of filtering the precipitate, it is
suffered to remain in the fluid from which it is precipitated, for 30 or
40 hours, it contracts considerably, and is converted into a thick
crystalline deposit. The supernatant liquor being poured off, the
crystals are to be washed and dried by exposure to the air.

The crystals thus procured are small, white, brilliant prisms, decom-
poseable into oxide of antimony by boiling in water, by continued
washing, or by an alkaline carbonate; they are entirely soluble in
nitric acid ; they fuse by the heat of a common lamp, and lose the
greater part of their chlorine.

The method of analysis adopted was very simple : a given quantity
of the salt was boiled in a solution of carbonate of potash; the solu-
tion, after saturation with nitric acid, was treated with nitrate of
silver; the residue gave the proportion of oxide of antimony. Another
less simple method was also employed: a quantity of the oxichloride
was heated by a spirit lamp in a bent tube, one end of which was
blown into a bulb. The greater part of the chlorine was condensed
in the cold part of the tube, which was separated from the bulb; the
chloride was dissolved in muriatic acid, and the antimony was preci-
pitated by tin. What remained in the bulb was dissolved by tartaric
acid, and afterwards treated with nitrate of silver. The metallic an-
timony on one hand, and the chloride of silver on the other, gave the
quantity of protochloride contained in the oxichloride analysed ; these
agreed perfectly with that obtained by carbonate of potash.

The analysis by carbonate of potash gave

Protochloride .... 24°72 .... 25°30..:... 25°19
Protoxide ....;. TREE snc (ALU ns AAS
Two analyses by fusion gave,
Protochloride .... 25°50
ARP ibe isle,

586 Intelligence and Miscellaneous Articles.

The mean of three analyses by carbonate of potash gave,

Calculated.
Protoxide of antimony .. 74°51 74:54
Protochloride of antimony 25°70 25°46

100°21 100-00

After having prepared sulphuretted hydrogen by muriatic acid
slightly diluted with water and sulphuret of antimony, it will be ob-
served that the solution remaining with the undissolved sulphuret
becomes red on cooling. If it be added to a great quantity of water,
an abundant yellowish precipitate is obtained, which, after some days,
becomes a thin stratum of small crystals of a fine red colour. These
crystals are merely the oxichloride coloured with variable quantities
of sulphuret of antimeny.—Ann. de Ch. et de Ph., lix, 220.

ON POTATOE STARCH. BY M. GUERIN-VARY.

The author divides his memoir into two parts. In the first he ex-
amines what substances accompany potatoe starch prepared with di-
stilled water, and considers several problems, including those proposed
by the commission of the Academy for examining the memoirs on
starch fecula, The second part contains the proximate analysis of
starch, as well as ultimate analysis of this substance, of amidine, of
exterior amidin (de l’amidin tégumentaire), of soluble amidin, and of
the exteriors (tégumens) insoluble in water and deprived of the pro-
perty of becoming blue with iodine.

In a former memoir M. Guérin has stated that potatoe starch, when
prepared with distilled water, contains, as foreign organic bodies, only
chlorophylle, and asubstance of a waxy appearance. M.Payen, on the
contrary, recognises in starch, besides other inorganic substances, a
volatile oil ready formed; and he also states that every specimen of
potatoe starch that he has examined possessed the property of re-
storing reddened litmus paper to its original colour, and contained
carbonate of lime. M. Guérin in this memoir shows that the alkaline
property of starch noticed by M. Payen is owing to the water which
is used for washing it; and that volatile oil does not exist ready
formed in the exteriors of starch, MM. Dubrunfaut and Beudant
stating that it is formed during the alcoholic fermentation of starch.

After noticing dextrine bread, M. Guérin gives the solutions of se-
veral problems, and arrives at the following conclusions :

Ist. Iodine has the same action on starch in water deprived of air,
as it has when the air is not expelled.

2nd. Starch heated only with either pure or saline water, in a close
vessel, gives a distilled liquor, which does not become blue on the
addition of iodine.

3rd. When starch is treated with diastase and water, in a retort
containing or not containing air, the distilled liquid does not turn
blue with iodine.

4th. Pure fecula exposed to air by itself, or moistened with water
for 48 hours at 113° or 115°, does not give rise to any carbonic nor
acetic acid, and does not appear altered under the microscope. Thus
the property of germinating, which is lost by the grains of certain de-

Intelligence and Miscellaneous Articles. 587

scription of corn after remaining for some hours in a damp soil at the
temperature of 113°Fahr., cannotbe attributed to any alteration which
pure and damp fecula undergoes, as MM. Colin and Edwards consider.

5th. By treating starch with sulphuric acid, according to the pro-
cess of M. de Saussure, no crystallizable compound could be obtained.

Having treated potatoe starch with alcoho! and water, to extract
the chlorophylle and the matter of a waxy appearance which it con-
tains, the author proceeded to its proximate analysis. By rubbing
this substance with water at 32° Fahr. until nothing more could be ex-
tracted from it, and evaporating the liquors in vacuo it left a residue
containing ADMIRE 5... 3:26 4.42 61°71

Amidin (soluble) .. 38:29—100-

The part exhausted by water at 32° having been treated with boil-
ing water, gave a liquor which by evaporation to dryness in vacuo,
afforded Amidine (0.5.04. 5.04 60°31

Amidin (soluble) .. 39°69—100°

The part insoluble in boiling water amounted to 2°12 per cent. of
the starch employed. From these experiments it appears that water
acts equally upon starch at afreezing or a boiling temperature. Now
as there is no known substance which by the mere action of water
at 32° is converted in several distinct products, except very dilute
nitrate of bismuth and other analogous products, the author concludes
that boiling water does not convert starch into amidine and soluble
amidin, as might be thought by the modifications that heat and water
cause in the constitution of many products of organization.

The above results give the following composition :

Exterior amidin.. 2°12
Soluble amidin .. 38°13
Amidine........ 59:75—100°

Several ultimate analyses of starch, of exterior and soluble ami-
dins, dried in vacuo at 275° Fahr., and the analysis of amidine dried
in vacuo at 239° Fahr., allow him to give the composition of these
substances as follows:

Starch = C!7 H'!° O'°; amidine C!° H® O¢ ; exterior amidin = so-
luble amidin C7 H® O+, or C'7 H1o Oto = Co H> O54C7 H> O+,

Starch = amidine + amidins.

These atomic formularies show that starch is equal to carbon and
water ; amidine to carbon, water, and oxygen ; and amidin to carbon,
water, and hydrogen. M. Guérin states that diastase converts exte-
rior and soluble amidin, when hydrated, into a substance like sugar,
and a substance insoluble in water, not rendered blue by iodine.
When these amidins are dried, diastase does not act upon them; 100
parts of starch contain 1-705 parts of insoluble matter, which does
not become blue with iodine, and which gives by analysis,

Ist Analysis. 2nd Analysis.
Carbon .... 47°71 47°68
Hydrogen.. 7:09 711
Oxygne .. 45°20—100° 45°21—100-

These analyses compared with those of exterior amidin show the
difference that exists between these substances; and the author is
inclined to consider exterior amidin as an immediate principle, and

588 Intelligence and Miscellaneous Articles.

not as a mixture of exteriors, not becoming blue with iodine and
amidine.—L Institut, 1"* Fev. 1336.

ARTIFICIAL CAMPHOR OR CAMPHOGENE.

M. Opperman obtains artificial camphor by passing a current of
dry hydrochloric acid gas into oil of turpentine. The absorption
of the gas is very rapid, particularly if the vessel containing the
oil of turpentine is surrounded by ice.

Two distinct substances are formed: the one solid, the other li-
quid. The solid substance, which is commonly called artificial
camphor, is composed of,

Carbone. ..4.. 0. 2c cence 70015
Biydrogen §0,6/5. 5. ile eto". 9°717
Chiorinewee. = 22 coe 20°272—100°004

This substance, when purified by sublimation, crystallizes in large
and lengthened crystals, its taste is aromatic but weak, it burns
with a very brilliant light, and colours the flame green, is soluble
in alcohol like common camphor; its solution does not form any
precipitate with nitrate of silver; the alkalies, lime, &c. decompose
it by combining with its hydrochloric acid. To obtain thebase of this
salt the camphor was distilled with hydrate of lime: a clear and
transparent oil was also obtained of a particular but weak odour, and
an aromatic taste, which became solid at — 44° Fahr.: its compo-
sition, ascertained by means of the apparatus of M. Liebig, is,

CarGOne, : ges Geran feitats ou 0 88-48
PA yd rope roe tas die es ahh 11-52—100:

This substance, which had been called by M. Dumas camphogene,
and by MM. Blanchet and Sell dadyle, is not acted upon either by
nitric or aceticacid ; but hydrochloric acidimmediately reproduces
artificial camphor.—L’ Institut, No. 149.

NEW ACID OF BROMINE.

M. Eugene Peligot is engaged in determining the action of chlo-
rine, bromine, and iodine on salts formed by the organic acids with
some of the metallic oxides, and has already arrived at results inter-
esting both from their novelty and from the generalization they
appear to present. When dry benzoate of silver is acted on by
bromine it is decomposed, and bromine is absorbed in large quan~
tity. There is produced, bromine of silver, and a new acid which re-
sembles benzoic acid in some of its physical properties, but differs ex-
tremely in its composition. It contains, besides the elements of ben-
zoic acid, all the oxygen of the oxide of silver and an atom of bromine.
It may be obtained anhydrous by treating the products of the action
by dry sulphuric ether, which dissolves the acid, and leaves the bro-
mide of silver.

At ordinary temperatures this acid is solid, but melts a little below
the boiling point of water; slightly soluble in cold, but extremely so
in boiling water, which upon cooling deposits the greater part of it :
it burns with a flame edged with green, indicating the presence of
bromine, which could not be recognised by a solution of nitrate of
silyer, this not precipitating with it ; it forms crystallizable salts with

Intelligence and Miscellaneous Articles. 589.

oxides, in which the oxygen of the acid to the oxygen of the base is
as 4 to I.

M. Peligot has endeavoured, without success, to form an analogous
acid by means of chlorine; the action is very violent, and inflamma-
tion and complete destruction of the salt ensues. This happens with
bromine if placed in contact with the salt in a fluid state ; it must be
acted on by passing the vapour of bromine slowly into it, which will
be absorbed. The action of iodine differs from that of bromine, for
it forms both iodide and iodate of silver; but the acid has not yet
been sufficiently examined to determine its nature.

The action of bromine on benzoate of silver is moreover not a par-
ticular action caused by the nature of benzoic acid, for it acts in a
similar manner on salts formed by acids which appear to be less dis-
posed to superoxygenation, as the oxalic and acetic acids, and every-
thing tends to the belief that the mode of action of this body will be-
come general.— L’ Institut, 15 Fev. 1836.

OBSERVATIONS ON THE SOLAR ECLIPSE OF MAY 15, 1836.
Photometrical Observations during the Eclipse, by Thos. Galloway, Esq.

To R. Taylor, Esq.
Dear Sir,

The following observations, made during the solar eclipse on the
15th instant with two of Leslie’s photometers, may be interesting to
some of yourreaders. The observations were made at Mr. Bishop’s
observatory in the Regent’s Park, and the photometers were placed
on a table on the lawn, fully exposed to the sun’s influence. With
the exception of a few passing clouds the sky remained clear till to-
wards the end of the eclipse, when the atmosphere became hazy.

Mean Time.| Phot. A. | Phot. B. || Mean Time. | Phot. A. | Phot, B.

h
1
2

Yours truly,
Sergeant’s Inn, May 24, 1836, Tuos. GALLowAY,

590 Intelligence and Miscellaneous Articles.

Extract of a Letter from R. V. Yates, Esq.. of Toateth Park,
Liverpool, dated Edinburgh, May 15, 1836.

«‘ We have just enjoyed a most glorious sight, an annular eclipse.
The morning arose cloudy, and gave little promise ; but about 10
the clouds cleared off, and during the whole period of the eclipse
nothing interfered with our seeing it perfectly. It was curious to
watch it when it was just going to become annular, the light broke
in so rapidly. It remained annular only a very short time, perhaps
between 5 and 10 minutes.”

Pp, M.

Pp. M. .
oh 1 5= Mh
Much gh 46™ $i"
obscurity.
Annular,
Air consi- a sy
derably 2" 58 4
offuscated.

In a garden near Birmingham the Gentians partially closed their
flowers during the eclipse, and then opened again,

The Rev. James Yates, by whom the above was communicated
to us, has obligingly directed our attention to the description of an
Annular Eclipse in the Norwegian Account of Haco’s Expedition
against Scotland, which we transcribe from p. 44 of that work.

pa er Hacon konongr 1a i Régnvalzyagi dré myrkr mikit 4 sdlina,
sva at litill hringr var biartur um sdlina utan*, ok hellt pri nockora
stund dags.

While King Haco lay in Ronaldsvo a great darkness drew over the
sun, so that only a little ring was bright round about the sun, and it
continued so for some time.

* Though relating to inquiries of a different class, I am tempted to note the
Islandic expression ‘‘wm solina utan,’’ as a remarkable illustration of the real
origin of our compound preposition Azour, ymbucan,—the noun being here in-
terposed between the two prepositions. See my Note on the complicated mistakes
in which the history of this word had been involved by Spelman, Skinner, and
Tooke, subjoined to the 8yo. edition of the Diversions of Purley, 1829, vol. i.
p. viiii—R, Taycor.

Intelligence and Miscellaneous Articles. 591

HYDRAULIC LIME,

M. Vicat communicated a paper to the Royal Academy of Sciences
at Paris on the sole efficacy of magnesia in rendering certain lime-
stones hydraulic. This paper has for its object the correction of
an opinion given by M. Berthier in the Journal des Mines of 1822,
that magnesia alone has no more efficacy than alumina to render
lime hydraulic; from which it would follow that silex was the only
essential principle in all cases.

M. Vicat was for a long time of the same opinion, which he now
declares is incorrect ; and says that magnesia alone, when in suffi-
cient quantity, will render pure lime hydraulic. He does not ex-
plain the degree of energy of these new species of lime, but only
affirms that they will solidify from the 6th to the 8th day, and con-
tinue to harden in the same manner as ordinary hydraulic lime.

Until his experiments are further advanced, he states that the
proportions of magnesia taken and weighed after calcination should
be from 30 to 40 of every 40 of pure anhydrous lime. The native
limestones examined and cited by M. Berthier contained only from
20 to 26 of magnesia for every 78 to 60 of lime : it is probable that
this want of proper proportions was the cause of his negative re-
sults. M. Vicat, in conclusion, points out the importance of these
observations,—hydraulic lime never having been found in the cal-
careous formation below the lias is because the dolomites have never
been examined, but it is now probable it may be found in this
lower formation.— L’ Institut, No. 153.

NOTE RESPECTING CERTAIN CONTROVERSIAL COMMUNICATIONS
LATELY SENT FOR INSERTION IN THIS JOURNAL.

LIEUT. LECOUNT.
We have received a letter from Licut. Lecount, claiming the in-
sertion, in its entire form, of his previous letter in reply to Mr, P.
Barlow, from which we gave an extract in our last N umber, p. 439.
Lieut. Lecount makes this claim on the ground “that it is the ge-
neral practice to allow any person who is attacked in a periodical
publication the right of replying.” We have merely to observe, in
answer, that our extract includes the real matter of Lieut. Lecount’s
reply, and that we omitted only irrelevant matter of a personal na-
ture, at the same time referring our readers to the pamphlet which
he has published. We must therefore decline all further allusion
to the subject.
We may remark in reference to this, as well as to other cases of a
similar kind which have lately occurred, that we cannot permit a
scientific discussion to degenerate into a personal controversy,

MR. HENWOOD.
We take the present opportunity of noticing Mr, Henwood’s letter
in the Records of General Science for May, to which the remark just

592 Intelligence and Miscellaneous Articles.

made is also applicable. There was a very sufficient reason for our
not inserting Mr. Henwood’s last reply to Mr. John Taylor on the
subject of the steam-engines of Cornwall, namely, that the quotation
itcontains from the Records of Mining is made in so garbled a manner
as to be a complete misrepresentation of Mr. Taylor's statement.
To prove this we give the passage entire as we find it in the Records
of Mining, including in brackets what Mr. Henwood has suppressed,
and by the suppression of which he has perverted the sense of the
whole.

«In the early part of the year (1813) the best duty was about
26 millions, by Captain Trevithick at Wheal Prosper, [Captain John
Davey at Wheal Alfred, and Messrs Jeffree and Gribble at Stray
Park. Towards the close of the year Captain Davey first attained
27 millions, then Jeffree and Gribble 28, and by the end of the year
the latter had nearly arrived at 30 millions.)”

One half of a sentence of the foregoing paragraph is thus brought
forward in contradiction of Mr. Taylor's statement that Captain
Trevithick’s “engine did only about 26 millions duty, and did not
equal other engines then working in the common way.” A reference
to the work itself showed us that if the remainder of the paragraph
had been given, it would at once have been seen that the imputation
was groundless. Can it reasonably be required of us to lend our
pages to charges thus supported ?

We will only add to this that the title « On anew Rotative Steam- »
Engine,” was prefixed to Mr, Taylor’s first paper not by him, but
by ourselves ; and the only sense in which we used the term “ new”
was in that of “newly or lately erected.” Mr. Henwood must have
been aware that Mr, Taylor had himself wholly precluded the sup-
position that it could mean “newly invented,” by mentioning an
older engine of the same description erected by Mr. Godfrey.

METEOROLOGICAL OBSERVATIONS FOR APRIL 1836.

Chiswick.—April 1. Dry haze: sleet: stormy with rain at night 2, 3. Cold
and windy. 4. Clear and fine. 5. Slight haze: cloudy: rain. 6, Rain:
cloudy. 7. Rain: clear. 8,9. Rain: cloudyand fine. 10. Fine. 11. Cold
haze: clear at night. 12. Overcast: rain. 13. Cloudy. 14, Overcast and
cold, 15. Slightrain. 16. Foggy. 17.Rain: cloudyand cold. 18. Drizzly:
fine. 19.Fine. 20.Cloudy: rain, 21. Very fine. 22. Rain: fine. 23, Rain.
24. Rain: stormy at night. 27. Cloudy and cold. 28. Overcast. 29, 30. Clear,
cold and dry.

Boston.—April 1. Fine: rain and snow p.m. 2. Cloudy. 3. Stormy :
rain and snow a.m. 4. Fine. 5. Cloudy. 6.Rain. 7. Rain. 8, Rain.
9. Cloudy. 10. Fine. 11. Cloudy. 12. Cloudy. 13. Cloudy: rain p.m.
14. Cloudy; rainp.m. 15. Cloudy. 16. Fine: raine.m. 17. Cloudy.
1s. Rain. 19. Fine: rainr.m. 20. Cloudy. 21. Fine. 292. Fine: rain
early a.m. 23.Fine. 24. Cloudy: rainearlya.m. 25. Cloudy. 26. Fine.
27. Rain. 28. Cloudy. 29. Fine: ice this morning. 30, Stormy.

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Third Series. Vol. § No, 50. Supplement.

INDEX to VOL. VIII.

—>—_

A xsorpTION, on, 58.

Achromatic microscope, 70.

Acids :—hydriodic, 191; hydrochloric,
353; suberic, 443; carbonic, 446,
583; arsenovinic, 447; new acid of
bromine, 588.

/Ether, on the formation of, 258.

Agassiz (Prof.) on the fossil beaks of
four species of Chimera, 6; on the
fossil fishes found in English collec-
tions, 72; the Wollaston Medal award-
ed to, 310.

Air, influence of its artificial rarefaction
and condensation in some diseases,
62: action of mushrooms on, 82.

Aldehyd, a new compound, 83.

Algebraic equations, 402; elimination,
538.

Alison (R. E.) on the earthquake of
Chili, Feb. 20, 1835, 74.

Ammonia, its action on the chlorides
and oxides of mercury, 495.

Animals, thermometer for determining
minute differences of temperature in,
57.

Antimony, on a supposed new sulphate
and oxide of, 476; crystallized oxi-
chloride of, 585.

Apjohn’s (Dr.) formula for inferring the
specific heats of gases, error in, 21.
Araneide, undescribed species of, 481.

Arches, skew, construction of, 299.

Architecture, on the entablature of Gre-
cian buildings, 430; Gothic, 449.

Arsenic, vaporization of, 190.

Arsenovinic acid, 447.

Astronomy :— improved astronomical
clock, 71; Newton and Flamstead,
139, 211, 218, 225; the aurora bo-
realis of Noy. 18, 184, 236, 350, 412,
439; Halley’s comet, 148, 173; Dr.
Brinkley, 155; Mr. Troughton, 155 ;
new observatory at Catania, 256; so-
lar eclipse of May 15, 293, 589, 590;
new method of reducing lunar obser-
vations, 373.

Atkinson (J.) on Sir G.S. Mackenzie’s
remarks on certain points in meteoro-
logy, 187.

Atmosphere, action of mushrooms on
the, 82; action of plants upon, 415.

Aurora borealis of Nov. 18, 154, 236,
350, 412, 439.

Babington (C. C.) on new British and
European plants, 345.

Babylon and Babel, non-identity of, 506.

Barlow (P.) on the theory of gradients
in railways, 97 ;.on Lecount’s trea-
tise on iron rails, 291.

Barlow (W. H.), experiments on Drum-
mond’s light, 238. ;

Barometer, self-registering, 67.

Barytes and strontia, separation of, 259.

Bat, long-eared, habits of, 265.

Bayfield (Capt.) on the transportation
of rocks by ice, 558.

Beck (Dr.) on the geology of Denmark,
553.

Beke (C. T.) on the Persian Gulf, and
on the non-identity of Babylon and
Babel, 506.

Berzelius (M.) on the properties of tel-
lurium, 84; symbolic notation first
introduced by, 101; on Faraday’s sup-
posed sulphate and oxide of antimony,
476.

Binney (E. W.) on a patch of red and
variegated marls, 571.

Blackwall (J.), characters of some un-
described species of Araneide, 481.

Botanical Society of Edinburgh, 440.

Botany :—Indian Gentianee, 75; two
species of the genus Pinus, 255; on
the Nephrodium rigidum, 255; va-
rieties of Erica ciliaris and Tetralia,
256; on several new British and
European plants, 345; on a species
of Agave, 346; Cooper’s Botanical
Rambles, 411; action of light upon
plants, and of: plants upon the atmo-
sphere, 415; on the ovula of Santa-
lum album, 423; W. Sherard and
Dillenius, 424; Botanical Society of
Edinburgh, 440; on the green colour
of plants, 469; on germination, 491.

Brayley (E. W. jun.), note on Mr. Chal-
lis’s paper on capillary attraction,
172

Breithaupt’s Mineralogy, 173.

Brewster (Sir D.) on the crystalline
lenses of animals, 195, 416; on the
lines of the solar spectrum, and on
those produced by the earth’s atmo-
sphere, and by the action of nitrous
acid gas, 384; on the colours of natu-
ral bodies, 468; on the optical pro-

NDEX,

perty of a substance resembling shell,
548.

Bridges, skew, construction of, 299.

Brinkley (Dr.), notice of, 155.

British Association, official report of the
Dublin Meeting, 58.

Broderip (W. J.) on the habits of the
Chimpanzee of the Zoological Gar-
dens, 164.

Bromine, on its conducting power for
electricity, 130, 400; new acid of, 588.

Brooke (H. J.) on symbolic notation,
101; on thulite and strémite, 169.

Buckland (Rev. Dr.) on the fossil beaks
of four extinct species of Chimera, 4.

C. S. on Whiston, Halley, and the Quar-
terly Reviewer of the ‘ Account of
Flamsteed’, 225.

Calamary, on the eye of the, 1.

Calculus, new renal, 446.

Caldcleugh (A.) on the earthquake in
Chili, Feb. 20, 1835, 148; account of
the volcanic eruption of Coseguina,
414.

Calorific rays, on, 23, 109, 186, 190, 248.

Cambridge Philosophical Society, 78,
429.

Camden Literary and Philosophical In-
stitution, 431.

Camphor, artificial, 588.

Capillary attraction, 89, 172, 288.

Carbohydrogen, nitrate of, 85.

Carbonic acid, solidification of, 446;
liquid, 583.

Cast-iron beams, Mr. Hodgkinson on,
65.

Catania, new observatory at, 256.

Cauchy's (M.) theory of double refrac-
tion, 104; undulatory theory of light,
7, 24, 112, 204, 247; 271, 305, 413;
new formuia for solving the problem
of interpolation, 459.

Cautley (Capt.) on the remains of mam-
malia found in the Sewalik moun-
tains, 575.

Challis (Rev. J.) on capillary attraction
and the molecular forces of fluids, 89;
on the phenomena of drops of oil
floating on water, 288.

Charlesworth (Edw.) on the crag-for-
mation, 529.

Chemical preparations, English, on the
frequent presence of lead in, 267.
Cheverton (Mr.) on mechanical sculp-

ture, 70.

Chili, earthquake of, Feb. 20, 1835, 74,

148.

Chimera, on the fossil beaks of four
species of, 4.
Chimpanzee, habits of the, 161.

995

Chloride of soda, its use in fever, 64.

Chlorine, on its conducting power for
electricity, 130, 400.

Christie (C. C.) on the aurora borealis
of Nov. 18, 1835, 412.

Chromium, crystallized oxide of, 175;
iodide of, 192.

Cod, crystalline lens of the, 193.

Cold, its effects on the body, 59.

Collision and impact, on, 65.

Colours of natural bodies, 468.

Comet, Halley’s, 148, 173.

Compass, steering, 71.

Cooper (E. J.) on Halley’s Comet, 148.

Cooper’s (D.) Flora Metropolitana, 411.

Cornwall, steam engines of, 20, 67, 136.

Crag formation, on the, 38, 138, 529.

Crichton (Sir A.), account of some fos-
sil remains, 574.

Crystallized surfaces, reflexion from,
103.

Culebrite, 261.

Cuming (H.) on the earthquake at Val-
paraiso, Noy. 1822, 159.

Cunningham (P.) on the attractions of
positive and negative electric cur-
rents, 550.

Cyanogen, compound of, 191.

Daniell (Prof.) on voltaic combinations,
421.

Darwin (F.), geological notes made dur-
ing a survey of the East and West
coasts of South America, 156.

Daubeny (Dr.) on Sir H. Davy’s theory
of volcanos, in reply to Dr. Davy, 249;
on the action of light upon plants, and
of plants upon the atmosphere, 415.

Davies (T. S.), geometrical investiga-
tions concerning terrestrial magne-
tism, 418.

Davy’s (Sir H.) electro-chemical theory,
subsidiary hypothesis to, 170.

Davy (Dr. J.), Dr. Daubeny’s reply to,
249; Prof. Faraday’s reply to, 521.
DeCandolle (M.) on the conditions of

germination, reply to, 491.

Del Rio (A.) on Riolite and Herrerite,

261.

Denham (Capt.) on vibration of rail-
ways, 70.

Denmark, geology of, 553.

Deshayes (M.), the Wollaston Donation
Fund awarded to, 311.

Dillenius (Prof.), short notice of, 424.

Don (Frof.), descriptions of Indian Gen-
liane@, 75; on two species of the
genus Pinus, 255; onthe Nephrodium
rigidum, 255; on varieties of Erica
ciliaris and Tetralia, 256.

Drummond’s light, on, 238.

3 M2

- 596

E., W. B. Note on Mr. Challis’s paper
_. on capillary attraction, 172.

Earthquake of Chili, 74, 148.

Earthquake waves, their effects on the
coasts of the Pacific, 181.

Eclipse, solar, 293, 589, 590.

Edmonds (R.) on the mirage, 169.

Education, scientific and general, 432.

Egerton (Sir P. G.), catalogue of fossil
fish, 367.

Elastic bodies, on the collision of, 65.

Electricity, 114, 130, 400, 421, 455,
550.

Electro-chemical theory of Sir H. Davy,
subsidiary hypothesis to, 170.

Electro-magnetic rotation, 521.

Entomology :—on the compound eyes of
insects, 202; on the yellow fly, 347;
Samouelle’sUseful Compendium, 412;
undescribed species of Araneid@, 481.

Equations, congeneric surd, 43; alge-
braic, 402; of the fifth degree, 538.

Equinoctial gales, on the, 187.

Eye:—of the Sepia Loligo, 1; crystal-
line lens, 193, 195, 416; on the com-
pound eyes of insects, 202.

F. W. Optical experiment, 168.

Faraday (Prof.), researches in electri-
city, 114; Royal Medal awarded to,
150; on the magnetic relations and
characters of the metals, 179; ona
supposed new sulphate and oxide of
antimony, 476; on the condensation
of the gases, in reply to Dr. Davy, 521.

Fever, use of chloride of soda in, 64.

Fishes, on the fossil beaks of four ex-
tinct species of, 4; fossil, 72, 366.

Flamsteed and Newton, 139, 211, 218,
225.

Fluids, molecular forces of, 89.

Forbes (Prof.) on the undulatory theory
of heat, 246; the Keith prize awarded
to, 424; on the mathematical form of
the Gothic pendent, 449; on the tem-
peratures of certain hot springs, and
on the verification of thermometers,
551.

Fossils:—beaks of the Chimera, 4;
fishes, 72; catalogue of fossil fish,
366; vertebre of fish, 557; vegetable
remains, 574.

Fox (C.) on the construction of skew
arches, 299.

Fox (R. W.) on the magnetic forces,
108.

Fractions, vanishing, 295, 398, 515.

Fresnel’'s law of double refraction, 104,
248.

Galloway (T.) on the solar eclipse,
May 15, 589.

INDEX.

Gases, specific heats of, 21; condensa-
tion of, 521.

Gentianeea, descriptions of Indian,
75.

Geological Society, 71, 156, 310.

Geology :—on the fossil beaks of four
species of Chimera, 4; geology of
West Norfolk, 28; discovery of fossil
fishes in the new red sandstone, 72;
on the gradual sinking of the west
coast of Greenland, 73; earthquake
of Chili, 74; on the crag formation,
38, 138, 529; notes made during a
survey of the east and west coasts of
S. America, 156; effects produced
at Valparaiso by the earthquake of
Nov. 1822, 159; effects of earthquake
waves on the coasts of the Pacific,
181; on physical geology, 227, 272,
357; anniversary proceedings of the
Geological Society, 310; catalogue
of fossil fish, 366; geological rela-
tions of certain hot springs, 551;
geology of Denmark, 553; occur-
rence of fossil vertebrz of fish in the
loess of the Rhine, 557; selenite in
the sands of the plastic clay, 558;
transportation of rocks by ice, 558;
syenite veins which traverse the mica
slate of Antrim, 559; geological
structure of Pembrokeshire, 561;
origin of the terms Silurian and
Cambrian systems, 561; on the gravel
and alluvia of S. Wales and Siluria,
566; ona patch of red and variegated
marls, 571; on the streams of sea
water in the island of Cephalonia,
573; on the caves of Ballybunian,
547; fossil vegetable remains, 574;
remains of mammalia found in the
Sewalik mountains, 575; fossil re-
mains of Saurian animals, 577; on
the ossiferous cavern of Yealm Bridge,
579.

German silver, analysis of, 80.

Germination, conditions of, 491.

Gibraltar Scientific Society, 256.

Gothic pendent, on the, 449.

Gradients on railways, 51, 97, 243.

Grant (T. T.) on protecting iron from
the action of salt water, 128.

Graves (Dr.) on the use of chloride of
soda in fever, 64.

Graves (J. T.) on the logarithms of
unity, 281.

Grecian buildings, on the entablature of,
430.

Greenland, on the gradual sinking of
part of the west coast of, 73.

Griffith (R.) on the syenite veins which

INDEX.

traverse the mica slate of Antrim,
559.

Guérin (M.) on potatoe starch, 586.

Hall (Dr. M.), description of a thermo-
meter for determining minute differ-
ences of temperature, 57.

Halley, remarks on, 144, 214, 220, 225.

Halley’s comet, 148, 1738.

Hamilton (Sir W. R.), Royal Medal
awarded by the Royal Society to, 150;
theorem respecting algebraic elimina-
tion, 538.

Handyside (Dr.) on the offices of lac-
teals, lymphatics, and veins in the
function of absorption, 58.

Hare’s (Dr.) voltaic trough, 116, 119.

Harris (W.S.) on the attractive and re-
pulsive forces of magnets, 349.

Heat :—radiant, 23, 109, 186, 190,
246,425; undulatory theory of, 246 ;
its circular polarization by total re-
flexion, 246; repulsive/power of, 189.

Heineken (N. S.) on the aurora bo-
realis of Nov. 18, 1835, 439.

Henwood (W. J.) on the steam engines
of Cornwall, 20, 591.

Herrerite, 261.

Herschel (Sir J. F. W.), meteorological

__ observations, 78; on scientific and ge-
neral education, 432.

Hodgkinson (E.) on impact and colli-
sion, 65.

Hope (Dr.), address on presenting the
Keith prize to Prof. Forbes, 424.

Hopkins (W.) on physical geology, 227,
272, 357.

Horner (L.) on a substance resembling
shell, 545.

Horner (W. G.) on congeneric surd
equations, 43.

Hudson (Dr.) on an error in Dr. Ap-
john’s formula for inferring the spe-
cific heats of dry gases, 21; on the
transmission of calorific rays, 109.

Hydriodic acid, a test for the vegetable
alkalies, 191.

Hydrochloric acid, its action on certain
sulphates, 353.

Hydrometer, Prof. Stevelly’s, 69.

Impact and collision, on, 65.

Inglis (Dr.) on iodine, 12, 191.

Insects, compound eyes of, 202.

Integral calculus, 515, 549.

Interpolation, M. Cauchy on, 459.

lodine:—essay on, 12,191; its conduct-
ing power for electricity, 130, 400.

Tron, on protecting it from the action of
salt-water, 128.

Jones (‘I’. W.) on the retina and pigment
of the eye of the Sepia Loligo, 1.

597

Johnson (KE. J.), magnetic experiments
on an iron steam-vessel, 547.

Kane (Dr.) on the action of hydro-
chloric acid on certain sulphates, 353 ;
on the action of ammonia on the
chlorides and oxides of mercury, 495.

Kater (Capt.), list of the papers contri-
buted by him to the Philosophical
Transactions, 151.

Keith (Rev. P.) on the conditions of
germination, 491.

Kelland (Mr.) on the dispersion of
light, 429.

Kennedy (Dr.) on purulent ophthalmia,
65

5.

Laplace’s (M.) capillary theory, on, 89;
coefficients, 474.

Lardner (Dr.) on the theory of gradients
in railways, 51.

Lead, cause of its presence in English
chemical preparations, 267.

Lecount (Lieut.), reply to Mr. Barlow,
439, 591.

Leigh (J.) on a patch of red and varie-
gated marls, 571.

Lens, crystalline, of animals, 193, 416.

Liebeg (M.) on aldehyd discovered by,
83.

Light :—apparatus for illustrating the
polarization of, 70; its action upon
plants, 415; undulatory theory of,
7, 24, 113, 204, 247, 270, 305, 413,
429, 500.

Lighthouses, experiments on Drum-
mond’s light for, 238.

Lime, hydraulic, 591.

Linnean Society, 75, 255, 345, 423,
580.

Liverpool tides, on the, 147, 418, 547.

Logarithms of unity, on, 281.

Lubbock (J. W.) on tide observations
made at Liverpool, 418.

Lunar observations, on reducing, 373.

Lyell (C.), address at anniversary of
the Geological Society, Feb. 19, 1836,
310; on the occurrence of fossil ver-
tebre of fish in the loess of the Rhine,
557.

MacCullagh (J.) on the laws of re-
flexion from crystallized surfaces, 103.

M‘Donnell (Dr.) on the differential
pulse, 63.

Magnetic action, 55, 108, 180, 242, 349.

experiments tried on board an
iron steam-vessel, 547.
forces, on the, 55, 108, 242,

349,

relations of the metals, 179.
Magnetism, researches in, 455; ter-
restrial, 418.

598

Magnets, attractive and repulsive forces
of, 349.

Manganese, sesquisulphate of, 173.

Marcet (M.) on the action of mush-
rooms on atmospheric air, 82.

Mathematics, 43, 281, 295, 393, 402,
515, 538, 549.

Melloni’s (M.) theory of the transmis-
sion of calorific rays, on, 23, 109,
186, 190, 246.

Mercury, action of ammonia on the
chlorides and oxides of, 495.

Metals, magnetic relations of the,
179.

Meteorology, 67, 78, 187, 256, 263,
351, 447, 592; table for Nov. 88; for
Dec. 176; for Jan. 264; for Feb. 352 ;
for Mar. 448; for Apr. 5938.

Microscope, achromatic, 70.

Miller (Prof.) on the measurement of
the axes of optical elasticity of certain
crystals, 431.

Mineral veins, 229.

Mineralogy, on symbolic notation as
applied to, 101; Breithaupt’s Mine-
ralogy, 173; on thulite and stromite,
169; culebrite, 261; Riolite and Her-
rerite, 261.

Mirage, as seen in Cornwall, 169.

Mitscherlich (E.) on nitro-benzide and
sulpho-benzide, 257; on the forma-
tion of zther, 258.

Mudge (Capt.) on the ossiferous cavern
of Yealm Bridge, 579.

Murchison (R. I.) on the discovery of
fossil fishes in the new red sandstone
of Tyrone, 72; on the geological
structure of Pembrokeshire, 561; on
the gravel and alluvia of South Wales
and Siluria, 566.

Murray (Sir J.) on the influence of ar-
tificial rarefaction in some diseases,
and the effects of its condensation in
others, 62.

Mushrooms, their action on atmospheric
air, 82.

Nephrodium rigidum, 255.

Newton and Flamsteed, 139, 211, 218,
225.

Newton’s Principia, inquiry relative to
Dr. Pemberton’s translation of, 441 ;
theory of natural colours, on, 468.

Nickel, separation of zinc from, 80.

Nitrate of carbohydrogen, 85.

Nitro-benzide and sulpho-benzide, 257.

Nitrogen, iodide of, 12, 13.

Nixon (J.), table of observed terrestrial
refractions, 479.

Notation, symbolic, as applied to mine-
ralogy, 101.

INDEX.

Oil, on the phznomena of drops of
floating on water, 288.

Ophthalmia, purulent, 65.

Opium, new alkali in, 444.

Optical experiment, 168 ; optical struc-
ture of the crystalline lenses of ani-
mals, 193.

Organic remains, 30, 32, 561, 576, 579.

Osborne (Dr.) on the effects of cold on
the human body, and on a mode of
measuring refrigeration, 59.

Oxacids, action of on pyroxylic spirit, 85.

Oxide of chromium, crystallized, 175. -

Parish (W.) on the effects of the earth-
quake waves on the coasts of the Pa-~
cific, 181.

Pemberton’s (Dr.) translation of New-
ton’s Principia, inquiry relative to,
441.

Pembrokeshire, geology of, 561, 567.

Persian Gulf, on the, 506.

Phillips (R.) on the action of oxacids on
pyroxylic spirit, 85.

Phloridzine, 444.

Pingel (Dr.) on the gradual sinking of
the west coast of Greenland, 73.

Pinus, descriptions of two species of,
255.

Poisson’s (M.) capillary theory, on, 89.

Polariscope, simple, 70.

Potatoe starch, 586.

Powell (Prof.), remarks on M. Melloni’s
paper on the transmission of calorific
rays, 23; on M. Cauchy’s theory of
the dispersion of light, 24, 204, 305 ;
on the theory of dispersion, 112;
note on the transmission of radiant
heat, 186; on the dispersion of light,
413.

Pratt (J. H.) on the proposition that a
function of @ and wz can be developed
in only one series of Laplace’s coefti-
cients, 474.

Prawn, on the growth of the, 421.

Precipitate, white, 498.

Pritchard (A.), apparatus for illustrat-
ing the polarization of light, 70.

Psychometer, or measurer of refrigera-
tion, 61.

Pulse, on the differential, 63.

Pyroxylic spirit, action of oxacids on, 85.

Quinine, iodide of, 191.

Radiant heat, 23, 109, 186,190, 246, 425.

Railways, theory of gradients in, 51,
97, 243; on vibration of, 70; re-
marks on iron rails, 291, 439.

Rainbow, explanation of, on the doc-
trine of interference, 78.

Rain-gauge, self-registering, 69.

Reflexion, 103, 246.

INDEX.

Refraction, 108, 479.

Refrigeration, mode of measuring, 59.

Resistance, on the solid of least, 66.

Retina of the eye of the common ca-
lamary, 1.

Reviews :—Whewell’s Newton and
Flamsteed, 139; Young’s Theory and
Solution of Algebraic Equations, 402;
Wiegmann’s Herpetologia Mexicana,
410; Cooper’s Flora Metropolitana,
411; Samouelle’s Entomologist’s Use-
ful Compendium, 412; Webster's
Principles of Hydrostatics,andTheory
of the Equilibrium and Motion of
Fluids, 544.

Richardson (W.) on selenite in the sands
of the plastic clay near Herne Bay,
558.

Rigaud (Prof.) on a note in the Quar-
terly Review respecting Mr. Whewell,
218; on Newton, Whiston, Halley,
and Flamsteed, 220; on the aurora
borealis of Nov. 18, 1885, 350; in-
quiry relative to Dr. Pemberton’s
translation of Newton’s Principia,441.

Riley (Dr.) on various fossil remains of
Saurian animals, 577.

Riolite, 261.

Ritchie (Dr.) on magnetic action, 55,
242; researches in electricity and
magnetism, 455.

Roberts (Mr.) on a machine which ren-
ders objects visible while revolving
200,000 times in a minute, 71.

Robinson (Dr.) on the aurora of Nov.
18, 1835, 236.

Rose (C. B.) on the geology of West
Norfolk, 28.

Royal Institution, 348.

Royal Society, 147, 412, 545.

Royal Society of Edinburgh, 424.

Rudberg’s (M.) undulatory theory of
dispersion, 28, 113, 210.

Rumker (C.), new method of reducing
lunar observations, 373.

Russell (J. S.) on the solid of least re-
sistance, 66.

Schweitzer (G.) on the cause of the
presence of lead in English chemical
preparations, 267.

Sculpture, production of busts, &c. by
machinery, 70.

Sepia Loligo, on the eye of the, 1.

Shell, on a substance resembling, 545.

Sherard (W.), the founder of the Pro-
fessorship of Botany at Oxford, 424.

Ships, new form for the construction of,
66.

Silver, German, analysis of, 80.

Smith (J. D.), analysis of German sil-

599

ver, and the separation of zine from
nickel, 80; on the separation of ba-
rytes and strontia, 259; on the com-
position of carbonate of zinc, 261.

Snow, red, 80.

Soda, chloride of, its use in fever, 64.

Solar eclipse of May 15, 298, 589, 590.

Solar spectrum, lines of the, 384.

Solid of least resistance, on the, 66.

Solly (E. jun.) on the conducting power
of iodine, bromine, and chlorine for
electricity, 130, 400.

Sowerby (J. de C.) on the habits of the
long-eared bat, 265.

Specific heats of dry gases, error in Dr.
Apjohn’s formula for inferring, 21.
Squire (T.) on the solar eclipse of

May 15, 298.

Starch, potatoe, 586.

Steam-engines :—improvements in, 71 ;
of Cornwall, 20,136; rotatory, 20,136.

Steam-vessel, iron, magnetic experi-
ments on, 547.

Stevelly (Prof.), description of a self-
registering barometer, 67.

Strigisan, a variety of wavellite, 173.

Stromite and thulite, 169.

Strontia and barytes, separation of, 259.

Sturgeon (W.), description of the aurora
borealis of Nov. 18, 134.

Stutchbury (S.) on various fossil re-
mains of Saurian animals, 577.

Suberic acid, 443.

Sulphate of copper, action of hydro-
chloric acid on, 353.

Sulpho-benzide and nitro-benzide, 257.

Sulphur, vaporization of, 189.

Sykes (Col.) on the caves of Ballybunian,
574.

Symbolic notation, on, 101.

Talbot (H. F.) on the repulsive power
of heat, 189; on the integral calculus,
549.

Taylor (J.) on the duty of steam-
engines in Cornwall, 67; on rotatory
steam-engines, 136.

Tellurium, properties of, 84.

Temperature, thermometer for deter-
mining minute differences of, 57.

Thebaia, a new alkali in opium, 444.

Thermal springs, temperature of, 551.

Thermometer :—for determining minute
differences of temperature, 57 ; fallacy
of determining climate by the, 61 ;
for measuring refrigeration, 61 ; veri-
fication of, 552.

Thompson (J.V.) on the metamorphoses
in the Macroura, 421.

Thomson (Dr.) on sesquisulphate of
manganese, 173.

600

Thulite and strémite, 169.

Tides, at Liverpool, 147, 418, 547; re-
marks on tides, 430.

Tovey (J.) on the relation between the
velocity and Jength of a wave of light,
7, 270, 500.

Undulatory theory, 7, 24, 113, 204, 247,
270, 305, 413, 429, 500.

Valparaiso, effects produced by the
earthquake of Nov. 1822 at, 159.
Volcanos, on the chemical theory of,
250; eruption of Coseguina, 414.
Voltaic battery, improved, 114; prac-
tical results of the, 121; voltaic com-
binations, 421 ; Hare’s voltaic trough,

116, 119.

Wagner (R.) on the compound eyes of
insects, 202.

Walford (E. B.), subsidiary hypothesis
to the electro-chemical theory of Sir
H. Davy, 170.

Wavellite, 173.

Webster’s Principles of Hydrostatics,
and Zheory of the Equilibrium and
Motion of Fluids, 544.

Whewell, (tev. W.), notice of his pam-
phlet “‘ Newton and Flamsteed,” 139;
reply to the Quarterly Review, 211 ;

INDEX.

on the tides in the port of Liverpool .

4

147; some observations on the tides,
430; researches on the tides, 547.

Whiston, remarks on, 214, 220, 225.

Wiegmann’s Herpetologia Mewicana,
410.

Willis (Rev. Mr.) on the composition of
me entablature of Grecian buildings,

30.

Wohler (F.) on crystallized oxide of
chromium, 175.

Woodward (S.) on the crag formation,
138.

Woolhouse (W. S. B.) on the theory of
gradients on railways, 243; on the
theory of vanishing fractions, 393.

Yarrell (W.) on a species of pipe-fish,
347; on an insect destructive to tur-
nips, 347.

Young (Prof.) on Mr. Woolhouse’s
theory of vanishing fractions, 295,
515; theory and solution of algebraic
equations, 402. :

Zinc, its separation from nickel, 80;
composition of carbonate of, 259;
plates, amalgamation of, 585.

Zoological Society, 161, 346.

END OF THE EIGHTH VOLUME.

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