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TRANSACTIONS

OF THE

ROW AI SOCIETY

OF

EDINBURGH.

VOL. XXI. .

EDINBURGH:

PUBLISHED BY ROBERT GRANT & SON, 82 PRINCES STREET.
AND WILLIAMS & NORGATEH, 14 HENRIETTA STREET, COVENT GARDEN, LONDON.

MDCCCLVII.

PRINTED BY NEILL AND COMPANY, EDINBURGH.

Pi:

Ill.

VE

VII.

Vil:

CONTENTS.

PART I. (1853-4.)

. On the Impregnation of the Ova of the Salmonide. By Joun Davy,

M.D., F.R.S. Lond. & Edin., Inspector-General of Army Hospitals,

On the Torbanehill Mineral. By Tuomas Stewart Tratty, M.D.,

F.R.S.E., Professor of Medical Jurisprudence in the University of

Edinburgh,

On a New Hygrometer or Dew-Point Instrument. By A. CoNNELL, Esq.,
F.R.S.E., Professor of Chemistry in the University of St Andrews,

. On the Action of the Halogen Compounds of Ethyl and Amyl on some

Vegetable Alkaloids. By Mr Henry How, Assistant to Professor
ANDERSON, Glasgow University, : : ;

- On a General Method of Substituting Iodine for Hydrogen in Organic

Compounds, and on the Properties of Iodopyromeconic Acid. By Mr
James F. Brown, Assistant to Dr ANDERSoN, Glasgow,

Note on the Possible Density of the Luminiferous Medium, and on the
Mechanical Value of a Cubie Mile of ac hii By Professor WIL-
LIAM THOMSON, . ;

On the Mechanical wm of the Solar pa By Professor WILLIAM
THOMSON, : : : : ;

On the Meteorology of the English Lake District, including the Results
of Experiments on the Fall of Rain, the Temperature, the Dew-Powt,
_ and the Humidity of the Atmosphere, at various Heights on the Moun-
tains, up to 3166 feet above the Sea Level, for the Years 1851, 1852,

VOL. XXI: 6b

PAGE

15

27

49

57

63

v1 CONTENTS.

and 1853. By Joun FLEeTcHER Miter, Ph. D., F.R.S., Fellow of
the Royal Astronomical Society, Associate of the Institution of
Civil Engineers, Member of the British Meteorological Society,
Corresponding Member of the Literary and eae Society of
Manchester, Xc., : »

IX. On the Dees Theory of Heat. Part V. Thermo-Electric Cur-
rents. By Witu1am THomson, M.A., Professor of Natural Philoso-
phy in the University of Glasgow,

X. An Investigation into the Structure of the Torbanehill Mineral, and of
various kinds of Coal. By Joun Hucues Bennett, M.D., F.R.S.E.,
Professor of Physiology in the reins of Bainburgh as
Two Plates.) -

XI. On certain Vegetable Organisms found in Coal from Fordel. By Joun
Hurton Batrour, M.D., F.L.S., Professor of Medicine and Botany
in the University of Edinburgh,

XII. Researches on some of the Crystalline Constituents of Opium. Second
Series. By TuHomas ANDERSON, M.D., Regius Professor of Chemis-
try in the University of Glasgow, .

XIII. On the Products of the Destructive Distillation of Animal Substances.
Part III. By Tuomas Anprrson, M.D., Regius Professor of Che-
mistry in the University of Glasgow, : 3

PART II. (1854-5.)

XIV. Further Experiments and Remarks on the Measurement of Heights by
the Boiling Point of Water. By James D. Forzzs, D.C.L., F.R.S.,
Sec. R.S.Ed., &., Professor of Natural Philosophy in the Univer-
sity of Edinburgh. (With a Plate.)

XV. Some Miscellaneous Remarks on the Salmonide. By Joun Davy, M.D.,
F.R.S. Lond. & Edin., Inspector-General of Army Hospitals,

PAGE

81

123

173

187

195

219

235

245

CONTENTS.

XVI. Notes on some of the Buddhist Opinions and Monuments of Asia,
compared with the Symbols on the Ancient Sculptured “* Standing
Stones” of Scotland. By Tuomas A. Wiss, M.D., F.R.S.E. (With
a Plate.) : : : 5 :

XVII. On Superposition. By the Rev. Puizip Kexianp, M.A., Professor
of Mathematics in the University of Edinburgh. (With a Plate.)

XVIII. Huxperiments on Colour, as perceived by the Eye, with Remarks on
Colour-Blindness. By James CLERK MAXxweELL, B.A., Trinity
College, Cambridge. Communicated by Dr Grecory. (With a
Plate.) i : t : ; :

XIX. Researches on the Amides of the Fatty Acids. By THomas H. Row-
NEY, Ph.D., F.C.8., Assistant in the College jp oe Glas-
gow, 3

XX. On the Volatile Bases produced by the Destructive Distillation of

Cinchonine. By C. GREVILLE WiLLIAMs, Assistant to Dr ANDER-
_ son, University of Glasgow,

XXI. On the Extent to which the recewed Theory of Vision requires us to
regard the Hye as a Camera Obscura. By Grorce Wixson, M.D.,
F.R.S.E., Director of the Industrial Museum of Scotland,

XXII. On Errors caused by Imperfect Inversion of the Magnet, on Observa-

tions of Magnetic Declination. By WittiamM Swan. (With a
Plate.) ; : : :

PART III. (1855-6.)

XXIII. On a Problem in Combinations. By the Rev. Puttip Kexuanp,
M.A., Professor of Mathematics in the University of Edinburgh,

XXIV. On Solar Light, and on a Simple Photometer. By Munco Ponton,
Hsq., F.R.S.E., : . : ,

vi

PAGE

255

275

299

309

327

349

309

363

Viil

XXYV.

XXVI.

XXVII.

XXVIII.

XXIX.

XXX.

XXXI.

XXXII.

XXXII.

XXXIV.

CONTENTS.

On. the Possibility of combining two or more Probabilities of the same
Event, so as to form one Definite Probability. me the a Rev.
Bishop Terrot, V.P.R.S.E., , :

Researches on Chinoline and its Homologues. By C. GREVILLE WIL-
Liams, Assistant to Dr ANDERson, University of Glasgow,

On Fermat's Theorem. By H. F. Tatzort, Esq., F.R.S., &. Com-
municated by Professor KELLAND, : ;

On a Proposition in the Theory of Numbers. By BALFour STEWART,
Esq., of the Kew Observatory. Communicated by Professor
KELLAND, :

On the Prismatic Spectra of the Flames of Compounds of Carbon and
Hydrogen. By WiuutaAm Swan, F.R.S.E.,

On the Laws of Structure of the more Disturbed Zones of the Earth’s
Crust. By Professor H. D. Rocers, Hon. F.R.S.E.,

PART IV. (1856-7.)

On New Forms of Marine Diatomacee, found in the Firth of Clyde
and in Loch Fine. By Wituiam Grecory, M.D., F.R.S.E.,
Professor of Chemistry. Illustrated by numerous Figures, drawn
by R. K. Grevitte, LL.D., F.R.S.E.,

On the Urinary Secretion of Fishes, with some Remarks on this Se-
cretion in other Classes of Animals. By Joun Davy, M.D.,
F.R.SS. Lond. & Edin.,

On the Minute Structure of Involuntary Muscular Fibre. By Jo-
SEPH ListER, Esq., F.R.C.S. Eng. & Edin., Assistant-Surgeon to

the Royal soda 2 roe Caitithni gate by Dr Curis-
TISON, :

On a Dynamical Top, for exhibiting the Phenomena of the Motion
of a System of Invariable Form about a Fixed Point, with some

PAGE

369

377

403

407

411

43]

473

543

549

CONTENTS, ix
PAGE

Suggestions as to the Earth’s Motion. By J. C. Maxws 1, B.A.,
Professor of Moral Philosophy in Marischal College, Aberdeen, 559

XXXV. On the Products of the Destructive Distillation of Animal Matters.
Part IV. By THomas Anpsrson, Professor of Chemistry, Uni-
versity of Glasgow, : : : : : Saal

XXXVL. On the Application of the Theory of Probabilities to the Question
of the Combination of Testimonies or Judgments. By GEORGE
Boots, LL.D., Professor of Mathematics in Queen’s College,

Cork, . ‘ ; ; » 00K
Proceedings at Statutory General Meetings, §c., : , . 655
List of the present Ordinary Members, in the order of their Election, . . 665
List of Non-Resident and Foreign Members, elected under the Old Laws, . 672
Honorary Fellows, : . 672
Fellows Deceased, Resigned, and Cancelled, ae om 1853 to 1857, . 614
Public Institutions, Sc., entitled to receive the Transactions and Proceedings of
the Society, : ; : ; : -, 616
Last of Donations, continued Bs om Vol. X X., p. 663, .. 678
Index, 701

VOL. XXI,

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THE KEITH, BRISBANE AND NEILDE PRIZES.

The above Prizes will be awarded by the Council in the following manner :—

KEITH PRIZE.

The Kerra Prize, consisting of a Gold Medal and from £40 to £50 in Money,
will be awarded early next Session (1857-8), for “the best communication on a
scientific subject, communicated, in the first instance, to the Royal Society dur-
ing the Sessions 1855-6 and 1856-7.” Preference will be given to a paper con-
taining a discovery.

MAKDOUGALL BRISBANE PRIZE.

This Prize, consisting of a Gold Medal and a sum of Money, will be awarded
before the close of the Session 1858-9, under the following conditions :—

1. Competing Essays are to be addressed to the Secretary of the Society on
or before Ist February 1859.

2. The competition is open to all men of science.

3. The Essays may be either anonymous or otherwise. In the former case,
they must be distinguished by mottoes, with corresponding sealed billets super-
scribed with the same motto, and containing the name of the Author.

4. The subject proposed by the Council for the Prize of 1856-57 is the fol-
lowing :—

A BroGrapuHicat NoticE oF A SCOTCHMAN EMINENT IN ScrENcE; including an
estimate of the influence and importance of his writings and discoveries. As
instances of such Biographies which still remain to be supplied, the Council
would specify the following names: Sir Ropert SIBBALD, Sir ANDREW Ba.rour,
Mactaurin, Buack, Monro Primus and Secundus; several of the family of
GreEGorY, Sir James Hatt, Jameson. The earlier volumes of the Transactions

2

of the Royal Society contain several specimens of able Biographies of the kind
here referred to. The Council are anxious to see a continuation of the series.

5. The Council impose no restriction as to the length of the Essays, which
may be, at the discretion of the Council, read at the Ordinary Meetings of the
Society. They wish also to leave the property and free disposal of the manu-
scripts to the Authors; a copy, however, being depbsited in the archives of the
Society, unless the Paper shall be published in the Transactions.

NEILL PRIZE.

The Council of the Royal Society of Edinburgh having received the bequest of
the late Dr Patrick Neiuu of the sum of £500, for the purpose of “ the interest
thereof being applied in furnishing a Medal or other reward every second or third
year to any distinguished Scottish Naturalist, according as such Medal or reward
shall be voted by the Council of the said Society,” hereby intimate,

1. That the First Nemt Prize, consisting of a Gold Medal and a sum of
Money, will be awarded before the close of the Session 1858-9.

2. The Prize will be given for a Paper of distinguished merit, on a subject of
Natural History, by a Scottish Naturalist, which shall have been presented to
the Society during the three years preceding the Ist February 1859,—or failing
presentation of a Paper sufficiently meritorious, it will be awarded for a work
or publication by some distinguished Scottish Naturalist, on some branch of
Natural History, bearing date within five years of the time of award.

10TH BIENNIAL Psriop, 1845-47,

117TH

1278

13TH

14TH

Do.

Do.

iS)

AWARDS OF THE KEITH PRIZE SINCE 1845.

(Continued from Transactions, Vol. XVI., page iii.)

1847-49.

1849-51.

1851-53.

1853-55.

General Sir THOMAS BrISBANE, Bart., for the Maker-
stoun Observations on Magnetic Phenomena, made at
his expense, and published in the Society’s Trans-
actions.*

Not awarded.

Professor KELLAND, for his papers on General Differ-
entiation, including his more recent communication
on a process of the Differential Calculus, and its
application to the solution of certain Differential
Equations.

W. J. Macquorn RANKINE, Esq., for his series of
papers on the Mechanical Action of Heat.

Dr THOMAS ANDERSON, for his papers on the Crys-
talline Constituents of Opium, and on the Products
of the Destructive Distillation of Animal Substances.

* A Silver Medal, bearing the head of Napier on one side, and a suitable inscription on the other, was at
the same time awarded to Mr Joun Atuan Broun, under whose immediate direction these Observations were

made.

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OF THE

ROYAL SOCIETY OF EDINBURGH. ~

AS REVISED 5rH JANUARY 1857.

in

, s ~
; De
« ‘

iA WS;

[By the Charter of the Society, (printed in the Transactions, Vol. VI., p. 5,) the Laws cannot

be altered, except at a Meeting held one month after that at which the Motion for
alteration shall have been proposed. |

i,

THE ROYAL SOCIETY OF EDINBURGH shall consist of Ordinary and
Honorary Fellows.

FE.

Every Ordinary Fellow, within three months after his election, shall pay Two
Guineas as the fee of admission, and Three Guineas as his contribution for the
Session in which he has been elected ; and annually at the commencement of every
Session, Three Guineas into the hands of the Treasurer. This annual contribution
shall continue for ten years after his admission, and it shall be limited to Two
Guineas for fifteen years thereafter.*

Tih

All Fellows who shall have paid Twenty-five years’ annual contribution shall
be exempt from farther payment.

IV.

The fees of admission of an Ordinary Non-Resident Fellow shall be £26, 5s.,
payable on his admission; and in case of any Non-Resident Fellow coming to
reside at any time in Scotland, he shall, during each year of his residence, pay the
usual annual contribution of £3, 3s., payable by each Resident Fellow; but after
payment of such annual contribution for eight years, he shall be exempt from any
farther payment. In the case of any Resident Fellow ceasing to reside in Scot-

* At the Meeting of the Society, on the 5th January 1857, when the reduction of the Contri-
butions from £3, 3s., to £2, 2s., from the 11th to the 25th year of membership, was adopted, it was
resolved that the existing Members shall share in this reduction, so far as regards their future
Annual Contributions.

A modification of this rule, in certain cases, was agreed to 3d January 1831.

Title.

The Fees of Ordi-

“nary Fellows resid-

ing in Scotland.

Payment to cease
after 25 years.

Fees of Non-Resi-
dent Ordinary
Fellows.

Case of Fellows —
becoming Non-Re-
sident.

Defaulters.

Privileges of
Ordinary Fellows,

Numbers Un-
limited.

Fellows entitled
to Transactions.

Mode of Recom-
mending Ordinary
Fellows.

Honorary Fellows,
British and
Foreign.

4

land, and wishing to continue a Fellow of the Society, it shall be in the power of
the Council to determine on what terms, in the circumstances of each case, the
privilege of remaining a Fellow of the Society shall be continued to such Fellow
while out of Scotland.

i

Members failing to pay their contribution for three successive years (due ap-
plication having been made to them by the Treasurer) shall be reported to the
Council, and, if they see fit, shall be declared from that period to be no longer
Fellows, and the legal means for recovering such arrears shall be employed.

Vi

None but ordinary Fellows shall bear any office in the Society, or vote in the
choice of Fellows or Office-Bearers, or interfere in the patrimonial interests of the
Society.

Vik
The number of Ordinary Fellows shall be unlimited.

VIII.

The Ordinary Fellows, upon producing an order from the TREAsuRER, shall be
entitled to receive from the Publisher, gratis, the Parts of the Society’s Trans-
actions which shall be published subsequent to their admission.

IX.

No person shall be proposed as an Ordinary Fellow without a recommenda-
tion subscribed by One Ordinary Fellow, to the purport below.* This recom-
mendation shall be delivered to the Secretary, and by him laid before the Council,
and shall afterwards be printed in the circulars for three Ordinary Meetings of
the Society, previous to the day of the election, and shall lie upon the table during
that time.

X

Honorary Fellows shall not be subject to any contribution. This class shall

* « A, B.,a gentleman well skilled in several branches of Science (or Polite Literature as the
‘* case may be), being to my knowledge desirous’ of becoming a Fellow of the Royal Society of Edin-
“ burgh, I hereby recommend him as deserving of that honour, and as likely to prove a useful and
“ valuable Member.”
This recommendation to be accompanied by a request of admission signed by the Candidate.

5

consist of persons eminently distinguished for science or literature. Its number
shall not exceed Fifty-six, of whom Twenty may be British subjects, and Thirty-
six may be subjects of foreign states.

XI.

Personages of Royal Blood may be elected Honorary Fellows, without regard
to the limitation of numbers specified in Law X.

EL

Honorary Fellows may be proposed by the Council, or by a recommendation
(in the form given below*) subscribed by three Ordinary Fellows ; and in case
the Council shall decline to bring this recommendation before the Society, it shall
be competent for the proposers to bring the same before a General Meeting. The
election shall be by ballot, after the proposal has been communicated wiva voce
from the Chair at one meeting, and printed in the circular for the meeting at
which the ballot is to take place.

XIII.

The election of Ordinary Fellows shall take place at the Ordinary Meetings of
the Society. The election shall be by ballot, and shall be determined by a majo-
rity of at least two-thirds of the votes, provided Twenty-four Fellows be present
and vote.

XIV.

The Ordinary Meetings shall be held on the first and third Mondays of every
month, from November to June inclusive. Regular minutes shall be kept of the
proceedings, and the Secretaries shall do the duty alternately, or according to such
agreement as they may find it convenient to make.

XV.

The Society shall from time to time publish its Transactions and Proceedings.
For this purpose the Council shall select and arrange the papers which they shall

* We hereby recommend—— ue panes A é
for the distinction of being made an Honorary Fellow of this Society, declaring that each of us from
our own knowledge of his services to (Literature or Science as the case may be) believe him to be
worthy of that honour.
(To be signed by three Ordinary Fellows.)

To the President and Council of Royal Society
of Edinburgh.

Royal Personages,

Recommendation
of Honorary Fel-
lows.

Mode of Election.

Election of Ordi-
nary Fellows.

Ordinary Meet-
ings.

The Transactions.

6
deem it expedient to publish in the Transactions of the Society, and shall super-
intend the printing of the same.

XVI.

How Published. The Transactions shall be published in Parts or Fasciculi at the close of each
session, and the expense shall be defrayed by the Society.
There shall be elected annually, for conducting the publications and regulating
The Council. the private business of the Society, a Council, consisting of a President ; Six Vice-
Presidents, two at least of whom shall be resident ; Twelve Counsellors, a General
Secretary, Two Secretaries to the Ordinary Meetings, a Treasurer, and a Curator
of the Museum and Library.

XVII.
Retiring Counsel- Four Counsellors shall go out annually, to be taken according to the order in
a which they stand on the list of the Council.

XVIII.
Election of Oficee | An Extraordinary Meeting for the Election of Office-Bearers shall be held on

Bearers.

the fourth Monday of November annually.

Pe Ee
Special Meetings ; Special Meetings of the Society may be called by the Secretary, by direction
ae of the Council; or on a requisition signed by six or more Ordinary Fellows.

Notice of not less than two days must be given of such meetings.

XX.

Treasurer's Duties. | Lhe Treasurer shall receive and disburse the mouey belonging to the Society,
granting the necessary receipts, and collecting the money when due.
He shall keép regular accounts of all the cash received and expended, which
shall be made up and balanced annually; and at the last Ordinary Meeting in
January he shall present the accounts for the preceding year, duly audited. At
this Meeting, the Treasurer shall also lay before the Council a list of all arrears
due above two years, and the Council shall thereupon give such directions as
they may deem necessary for recovery thereof.

AO.

At the Extraordinary Meeting in November, a Committee of three Fellows
shall be chosen to audit the Treasurer’s accounts, and give the necessary discharge
of his intromissions.

Auditors.

7

The report of the examination and discharge shall be laid before the Society
at the last Ordinary Meeting in January, and inserted in the records.

XXII.

The General Secretary shall keep Minutes of the Extraordinary Meetings of General Searctaayie
the Society, and of the Meetings of the Council, in two distinct books. He
shall, under the direction of the Council, conduct the correspondence of the Society,
and superintend its publications. For these purposes, he shall, when necessary,
employ a clerk, to be paid by the Society.

The Secretaries to the Ordinary Meetings shall keep a regular Minute-book, in geeerctarionaa
which a full account of the proceedings of these Meetings shall be entered; they ee
shall specify all the Donations received, and furnish a list of them, and of the
donors’ names, to the Curator of the Library and Museum: they shall likewise
furnish the Treasurer with notes of all admissions of Ordinary Fellows. They
shall assist the General Secretary in superintending the publications, and in his
absence shall take his duty.

P.O.G 108

The Curator of the Museum and Library shall have the custody and charge of pore eon
all the Books, Manuscripts, objects of Natural History, Scientific Productions, and
other articles of a similar description belonging to the Society ; he shall take an
account of these when received, and keep a regular catalogue of the whole, which
shall lie in the Hall, for the inspection of the Fellows.

XOXEY..

All articles of the above description shall be open to the inspection of the Use of Museum
Fellows, at the Hall of the Society, at such times, and under such regulations, as aia
the Council from time to time shall appoint.

XXV.

A Register shall be kept, in which the names of the Fellows shall be enrolled Register Book.
at their admission, with the date.

PRINTED BY NEILL & CO., EDINBURGH.

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TRANSACTIONS.

I.—On the Impregnation of the Ova of the Salmonide. By Joun Davy, M.D.,
F.R.S. Lond. & Edin., Inspector-General of Army Hospitals.

(Read 6th March 1854.)

From time to time it has been asserted, that the function of impregnation of
the ova of these fish is performed after the manner of that of the cartilaginous,
viz., before exclusion. The instances related in proof are commonly of a vague
kind, and such that little credit can be attached to them. Recently a more precise
example has been adduced,—how the ova of the trout, taken from the abdomen of
the parent fish, and placed ina “running stream” apart, included in a perforated
box, in due time were hatched, producing young fish. The particulars of the
experiment, and the result, were published in the spring of last year, and in more
than one of the provincial papers; and Dr Rosertson of Dunkeld was named as
the institutor and reporter of the trial.

Considering the manner in which this statement was made and received, and
the practical conclusion deduced,—that no longer any trouble need be taken in
the artificial mode of breeding to obtain the milt to apply to the roe, I have
thought it worth while to give the subject some attention, on the supposition that
the result, as stated, may have been accurate, being, as it appeared to me
to be, within the limits of possibility,—though I cannot say, keeping in mind
the structure of the male and female fish, and all the information hitherto col-
lected respecting the manner in which the generative process is carried on by
them,—that it is within the limits of probability.

I shall first briefly notice some trials which have been made, and with a view
to determine the question.

Mr Saw, in his valuable paper on the Development and Growth of Salmon
Fry, published in 1840 in the Transactions of this Society, describes how, in two
instances, he obtained negative results in experiments on mature ova of the sal-

VOL. XXI. PART I. A

2 DR DAVY ON THE IMPREGNATION OF

mon which had not been mixed with milt after exclusion, though in all other
respects placed and treated like other ova from the same fish,—ova which had
been mixed with milt after their exclusion, and were thereby impregnated, and
rendered prolific.

Mr Young, in his Natural History of the Salmon, gives an account of some
experiments with a similar negative result. In page 17, he states, “ We have
often experimented on the ova of fishes, merely to arrive at facts. We have im-
pregnated one part of the ova of the fish with milt, and have left part unimpreg-
nated, and then deposited both parts in the same stream, at the same depth, and
in a current of exactly the same velocity. But never, in any one instance, did we
find one grain of the unimpregnated part productive, while the other portion that
was impregnated with the milt never failed to produce fry in due time.” He
adds, “ This has been frequently tried. and has at all times proved the same.”

Mr AsHwortH, by whom the production of salmon on a large scale has been
so successfully carried on in Ireland, informs me, in a letter with which he has
favoured me, of a similarenegative result,—how Mr Ramssorttom, in his employ,
“took a female fish (a salmon) and extracted a quantity of eggs; then placed
them in a box alone, without impregnating them with the milt, and none of them
came to life; and how “he took the remainder of the ova from the same fish,
and impregnated them with the milt, and these produced young fish.”

The trials | have made have afforded similar negative results. I shall men-
tion three in particular.

On the 10th of last November, from a stream in’ which there were known to
be male fish with mature milt, two female trouts were taken with fully formed
ova,—ova that were expelled by the application of gentle pressure to the abdo-
men. These were placed on gravel in a glass vessel with water, which was changed
twice daily; they exhibited no marks of development, and one after another
became opaque from imbibing water.

On the 25th of the same month, [ procured two charr from Windermere,—a
male and female fish, taken from a shoal in the lake, a breeding bed. On gentle
pressure to the abdomen, ova in large quantity were obtained, and abundance of
spermatic fluid ; each fish at the time was alive. A portion of the ova was placed
in three glass vessels with gravel and water, without having been allowed to
come in contact with the milt. Another portion of them was mixed with the
milt, and similarly distributed. The vessels were kept in a room of pretty equable
temperature, which ranged from about 51° Fahr. to 44°, that is, from the com-
mencement to the present time, and the water—spring water—was changed
daily once, and no oftener. Now, January 4th, a large number of the eggs which
had been mixed with the milt are well advanced, the foetal fish being visible
in the ova with the naked eye, and this in each of the three vessels; but, on the
contrary, in the other three vessels, not one egg bears any marks. of vital pro-

THE OVA OF THE SALMONIDA. 3

gress; many of them have become opaque; the majority of them, and those
which remain transparent, are of uniform appearance, whether seen with the
naked eye or under the microscope. Under a one-inch object-glass, in all of
them, at one spot, a patch, as it were of cellular tissue, is observable, seemingly
adhering to the membrane of the egg, with oil globules entangled in and sur-
rounding it.

On the 2d December, I procured some eges from two charr, taken at the same
time as the preceding, and from the same breeding shoal, and kept in company
with male fish in a well fed by a small stream. The eggs, obtained by pressure
to the abdomen, were the few remaining, the greater portion having been pre-
viously shed, as was manifest from the lankness of the fish. From this circum-
stance, they seemed peculiarly favourable for the trial, on the hypothesis of
the possible admission of the spermatic fluid ab exvierno. But the result was
equally negative with the foregoing. The ova put into water, the same as that
used with the impregnated, fertile ova, and under the same circumstances, all
underwent no change, excepting that denoting loss of vitality.

Many other instances of the like kind I could relate, that have been commu-
nicated by friends interested in the subject; but I hardly think them necessary,
those I have given appearing to me so conclusive, even on the doctrine of chances.

Next, it may be well to advert to the structure of the male and female of the
Salmonidee, to which I have alluded, as seeming to render impregnation from
without very improbable.

The female, as it is well known, has no true oviduct, as in the instance of
the cartilaginous fish. Her ovaries are not connected with any permanent open-
ings; an aperture for their escape being made only just before the exclusion
of the ova,—that is, when the ova are mature and detached from the ovaries, and
when, by their volume, they distend and press on every part of the peritonzeal
sac, but necessarily with most effect where there is least resistance, viz., close to
the anus, the very spot where the aperture is to be formed with a suitable struc-
ture for their exit. How ill adapted is this for the required effect, according to
the supposition of impregnation of the ova before exclusion? Moreover, as re-
gards the male fish, we see the same inaptitude exhibited in the conformation of
its generative organs. They are of the simplest kind, the testes terminating in
an aperture close to the anal end of the intestine, without even a distinct papilla
furnished with erectile tissue, and open only whilst needed for the outpouring
of the abundant spermatic fluid, distending the organs in which it is secreted,
and by them distending the abdomen.

The inaptitude of the organs in both sexes for the presumed office is the more
manifest, as it has seemed to me, the closer the attention is given to the minute
structure of the parts concerned. In the instance of the female, the aperture is
in a vascular papilla, prominent at the verge of the anus, and internally pro-

4 DR DAVY ON THE IMPREGNATION OF

vided with folds,—a somewhat valvular structure, that reminds one of the mouth
of the common gall-duct in man,—allowing a free passage to a probe downwards,
but not in the opposite direction, and being amply provided with mucous fol-
licles, forming a provisional mucous duct, the better adapted to the descent of
the ova.* In the male, the testes terminate in a common duct, slightly promi-
nent within the verge of the anus,—the projection so small as hardly to deserve
the name even of papilla, very much smaller than that of the female, and neither
vascular, so far as I could ascertain, except in the ordinary manner, nor provided
with any follicles, such as usually belong to the part destined for the purpose
supposed.

Further, if attention be given to the manner in which the male and female
fish behave during the spawning time, I think we shall have confirmation that
there is no act of intromission,—which indeed, anatomically considered, it may
be presumed there cannot be,—but also that there is no attempt made favour-
ing the notion that the spermatic fluid is injected (as would be necessary for the
impregnation of the ova) into the cavity of the abdomen of the female. That
the fish in the act of spawning sometimes come in contact, pressing against each
other, and thereby aiding the expulsion of the ova and milt, cannot, I think, be
doubted. By many observant fishermen, poachers addicted to the taking of the
fish at the time of their spawning, I have been assured of the fact from their own
observations; but this is very different from the act of copulation as performed
in other classes of animals in which impregnation is effected before the expulsion
of the ova; but though so dissimilar, perfectly suitable to the end required, and
quite in accordance, as we have proof in the artificial process, with the neces-
sary requirements.

It is an axiom that nature does nothing in vain; it is not less true that na-
ture is perfect in her works, as regards the adaptation of means to ends. In no
part of the animal economy is this more strongly and happily illustrated than in
the generative system of organs, diversiform and varied as they are in the several
classes of animals. Consistently, then, were the mode of impregnation that
which has been asserted, we may be sure that an organization,—an apparatus
would have been provided suitable to it. Also, as I think consistently with the
hypothesis, we might expect occasionally to find ova in the cavity of the abdo-
men, bearing marks, if they had been impregnated there, of incipient develop-
ment, according to the analogy of extra uterine foetal growth sometimes witnessed
in the Mammalia; but none have been described, that I am aware of, as ever
observed. In spent fish, that is, those which have spawned, in the instance both

* The closure of this aperture, after the exclusion of the ova, from such observations as I have
made, appears to take place slowly, requiring many weeks for its accomplishment, and when effected,
by so delicate a medium as to be easily ruptured, To be properly examined, the fish should, after being
opened, be placed under water, and the blow-pipe be used before the probe.

THE OVA OF THE SALMONIDZ. 9)

of the salmon and trout, I have in spring found mature transparent ova detached
from their ovaries, so included, when the aperture for the passage of the ova was
closed, or almost so; but they were totally destitute of any appearance of vital
development.

In conclusion, granting the observations referred to—of the hatching of the
ova of the trout in the manner described, viz., without milt, so far as was known,
being brought into contact with the expressed ova—to be accurate in their detail,
it may be asked, Does the result, as stated, warrant the inference that impreg-
nation was effected before the expulsion of the ova? The box, we are informed,
containing them was placed ina stream. What is more likely than that they
might have been impregnated, so included but not insulated, by the spermatic
eranules, the spermatozoa of milt shed by some fish in the adjoining water? The
diffusibility of these living granules—not the least remarkable of their quali-
ties—seems to be favourable to this conclusion.

LESKETH How, AMBLESIDE,
January 4, 1854,

VOL. XXI. PART I. B

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Il.—On the Torbanehill Mineral. By Tuomas Stewart Trai, M.D., F.R.S.E.,
Professor of Medical Jurisprudence in the University of Edinburgh.

(Read 5th December 1853.)

It is well known to the Society, that a mineral, found in the strata of Torbane-
hill, not far from Bathgate, in the county of Linlithgow, has lately been the sub-
ject of a keen lawsuit. Specimens of this mineral were early in the year put
into my hands by the lessee, and sometime afterwards by the proprietor of Tor-
banehill, for the purpose of obtaining a mineralogical opinion on the nature of
the mineral. I stated at the time to both parties, that I would carefully examine
it before I could presume to offer a decided opinion. In fact, the mineral was
not altogether new to me; for, in the two preceding years, I had received speci-
mens of a mineral from Torbanehill, and from Boghead, which I was unable to
refer to any described species; and I was therefore determined to give my opi-
nion with due caution, especially as I understood that large interests were in-
volved in the question.

After carefully comparing its characters with a great number of different
kinds of coal, of bituminous shale, and asphalt, with all of which it presented
affinities, and after a considerable number of experiments on its chemical cha-
racters, I came to the conclusion, that it was a mineral distinct from either, and
so peculiar as to deserve a particular name. From its qualities, I proposed for it
the designation of BITUMENITE, as it seemed to consist of much bitumen, mingled
with earthy matter.

This opinion I mentioned to one or two friends, and soon after, I received an
intimation, that I should be requested to attend as a witness on the part of the
proprietor. From his agents, however, supposing that they had enough of scientific
evidence on their side, I was not examined on the trial.

I had been requested to examine the mineral in its native bed ; and, accord-
ingly, went to Torbanehill, and saw the works. There were four pits or shafts,
but No. 1 was no longer wrought; Nos. 2, 3, and 4 were in active operation, and
large blocks of the mineral lay around the mouths of these pits. The quality of
the mineral extracted from each appeared to the eye nearly similar; the blocks
varying in thickness, from 1 foot 4 inches to 1 foot 11 inches.

VOL. XXI. PART 1. Cc

8 , DR TRAILL ON THE TORBANEHILL MINERAL.

I descended into No. 2, which was wrought by a small steam-engine. The
depth of the shaft was 17 fathoms. From the bottom of the shaft, a drift was
carried for 80 yards, in a northerly direction, with a dip of about 1 in 12, almost
half-way between No. 1 and No. 3. This working was so low, that we could not
stand upright; and the most convenient mode of exploring its termination, or the
face, as it is technically termed, is to lie at full length in a truck, and to be leisurely
let down the incline. In descending, the succession of the strata are :—

_ 1. A thick roof of sandstone.

2. Faeks, a crumbling shale=4 inches in thickness. This bed in No. 3 is want-
ing; but it forms the roof in No. 4. ;

3. Cement, a mixture of shale and a poor ironstone=3 inches.

4. Bitumenite, which in this pit at the face=1 foot 4 inches in thickness.

5. Fine Ironstone, from 2 inches to 4 inch.

6. Bituminous Shale, often containing tabular masses of good ironstone=
2 inches.

7. An inferior coal=7 inches. These four last-mentioned beds are all raised

with the Bitumenite, and together measure 2 feet 3 inches in thickness.

8. Coal, much mixed with shale, here called foul coal, about 2 feet 4 inches.

9. Fire-clay.

These notices will sufficiently shew the position of the Bitumenite, &c., which
has nothing peculiar in its situation in the earth to distinguish it from any other
mineral occurring in a coal-field. It seems, however, to be thickest near the top
of the field, as in No. 4, and to diminish a little in thickness in the other two pits.

I had the pleasure of visiting Torbanehill with one of the most eminent and
experienced coal-surveyors of England, Mr Nicnotas Woop, President of the
North of England Institute of Mining Engineers, and asked him, “ If you had
bored at Torbanehill before the working of the shafts, would you, from what the
instrument brought up, have said that there was here a workable coal?” He an-
swered, ‘‘ Decidedly not. The 7-inch coal is not workable; and the substance
you call Bitwmenite | should have considered as a shale.”

I have compared Bitumenite with a great number of different coals, as with
common English coal, Wigan cannel, and with several varieties of Scottish coals,

1. Lord Stair’s cannel or parrot coal, from Oxenford.

2. Marquis of Lothian’s parrot coal.

3. West Wemyss parrot coal.

4, Arniston parrot coal.

5. Methill coal, which, however, approaches more nearly to bituminous shale
than to common coal, having a nearly dull fracture, though with a strongly
shining streak unchanged in colour.

DR TRAILL ON THE TORBANEHILL MINERAL. 9

. Three sorts of Capeldrae coal.

. Two sorts of Lochgelly parrot coal.

. Duke of Hamilton’s Lesmahago cannel or parrot coal.

. Mr Ferguson’s parrot coal.

10. Kingswood parrot coal.

11. Cowdenhillhead parrot coal.

12. West Wemyss ums, which is little better than a bituminous shale.

C ON DD

Mineralogists distinguish mineral species chiefly by what are termed external
characters, aided by a few simple chemical results.

The Torbanehill mineral differs in mzneralogical characters from all these;
especially in having some degree of translucency on the edges, when examined in
thin fragments by a strong light; in having a streak not shining, but dull; and
which is strongly coloured of a pale ochre-yellow hue; whereas every coal has a
shining streak, which is not changed in colour. The fracture, too, of every coal
affording an abundant gas, as Bitumenite does, is glistening or shining; but the
fracture of Bitumenite is perfectly dull. Coal is brittle, or easily broken; but
Bitumenite, though it split readily in the direction of the bed, is not easily fran-
gible in a cross direction. When so struck with a hammer, it resists, and shews
very considerable elasticity, causing recoil of the hammer; as was remarked both
by Mr Woop and me when procuring specimens of the mineral at the three pits.
It has been formed into snuff-boxes in the turning-lathe; but it does not take a
polish, and looks dull from this circumstance.

When moderately heated, Bitumenite catches fire almost as readily as as-
phalt, and burns with a dense white flame, emitting much smoke; but the flame
dies away without igniting the mass. In fact, when burnt by itself in a grate, this
mineral scarcely produces the glow of ignition, and neither fuses or cakes like every
bituminous coal, nor forms cinders ; but it leaves a very white mass of nearly the
form of the fragments put into the grate; which mass, however, is very brittle,
and easily reduced to a fine powder. It therefore is deficient in one important
quality of common coal, that of forming a bright ignited mass, calculated for the
roasting of meat, or for completing other culinary operations by radiant heat.

It is distinguished from asphalt by its streak, its tenacity, and by not melting
when heated before it inflames.

The Torbanehill mineral is distinguished from bituminous shale by its streak,
its tenacity, its cleavage, by its far more ready inflammability, and by the smaller
proportion of its earthy residue when burnt, as well as by its far more abundant
yield of inflammable gas.

On analyzing three different specimens of Bitumenite, I found the proportion.
of volatile and fixed ingredients somewhat different in each.

10 DR TRAILL ON THE TORBANEHILL MINERAL.

a. Yielded 27°5 residue, and 72°4 per cent. was dissipated.
b= wig Qikd ee 7 Vomuae, >
ci re eo BL ee Ls

One hundred grains of Bitumenite afforded by distillation 60°5 cubic inches
of inflammable gas, which is equivalent to rather more than 274 cubic feet per
cwt.; and this gas had a far greater illuminating power than the best coal gas I
have ever examined. I considered it in this respect to approach nearer to oil gas
than to common coal gas. I did not, however, determine the comparative illu-
minating power by the best test, chlorine, but estimated its superiority by the eye.

Besides this, the distillation afforded a considerable quantity of the chemical
compound known by the name of Parafine, a substance now used to grease ma-
chinery, and for other economical purposes; a product which I have not ob-
tained from coal when distilled for gas.

[ am well aware that by a slow distillation with a moderate heat, Paraffine
may be procured from certain kinds of coal, from peat, from bitumens, and per-
haps from every substance capable of yielding olefiant gas, or what has been
termed Bicarburetted Hydrogene ; for their atomic constitution seems to be nearly
similar —C4+H4, or some multiple of these. This substance has been manufac-
tured in large quantities from Bitumenite by Mr Youne, as the specimen on the
table will shew.

By distillation, too, petroleum may be obtained from it, especially if the mi-
neral be first allowed to imbibe as much water as it can absorb; and this pro-
duct is more abundant, more than is yielded by any coal. The fixed residue of the
combustion of Bitumenite consists chiefly of silex and alumina, with traces of
lime and oxide of iron.

Bitumenite occasionally contains casts of vegetable remains, especially of
large Stigmarie. A very magnificent specimen of Stigmaria in Bitumenite, as
thick as the human body, has been deposited by Dr Curistison in the University
Museum. In examining the structure of thin slices by the microscope, I per-
ceived where the organisms occurred some traces of vegetable structure; but in
other portions of the mineral I was unable to perceive the least trace of organic
structure. In several specimens, in the hands of Mr Sanperson the lapidary, I
was also unable to see real organic structure; but observed numerous globules of
a pale yellowish matter, which I take to be bituminous particles disseminated
among the opaque earthy ingredients.

But even if such organic texture could be traced in every part of it, still this
would not constitute it a coal; for organic structure is constantly seen. too, in
mineral charcoal, in surtarbrandr, in peat, and in petrified wood; yet nobody
would denominate these varieties of coal.

DR TRAILL ON THE TORBANEHILL MINERAL. 11

One person insisted, that, as the mineral contained carbon, was inflammable,
and occurred in a coal formation, it must be considered asa coal. To this I would
reply, Must we consider as coals—Naphtha, Petroleum, Asphalt, Amber, Mellite,
or the rarer minerals, Piauzite, Ixolite, Schererite, Hartine, Walchowite, Middle-
tonite, Retinite, Hartite, Ozokerite, &c., all which are inflammables, contain car-
bon, and occur in the coal formation ?

On these grounds I consider the Torbanehill mineral not to be a coal, but a
mineral not hitherto described in our systems of mineralogy, and for which I have
proposed the name of

BITUMENITE;
and which has the following mineralogical characters.

a. Colour passing from blackish-brown (108, Syme) to liver-brown (104), and
often spotted with hair-brown (105).

6. It occurs massive.

c. It is dull in every direction.

d. Fracture—principal fracture flat, conchoidal, inclining to splintery; cross
fracture uneven, slaty.

e. Fragments are indeterminately angular, with sharp edges.

J. Examined by a strong light, the sharp edges are feebly translucent, admit-
ting a dark reddish-brown light.

g. It yields to the hammer in the direction of the bed, but resists blows at
right angles to that direction, and is rather difficult to break, exhibiting a consi-
derable degree of elasticity, and causing the hammer to rebound smartly.

h. It is, however, soft and sectile.

7. Its streak is quite dull, and has a pale ochre-yellow hue.

k. Its specific gravity = 1-284.

Chemical Characters.

a. It is very inflammable, readily catching fire without melting, burning with
a dense white flame, and much smoke. When ignited at a lamp, it continues to
burn a considerable time. Some bituminous shales will also thus burn for a
shorter time, but they leave their edges more or less white ; but with Bitumenite,
when the flame expires, the form of the fragment is unchanged, and it is wholly
covered with a black carbonaceous matter, derived from the dense smoke of its
flame.

b. When exposed to a strong red-heat in a platinum crucible for 23 hours, it
left behind a white matter, retaining the shape of the original fragments, but
readily crumbling on pressure into a grayish-white powder; but no part of it was
converted into a slag.

ce. When distilled in a small iron retort, it afforded an abundant dense inflam-
mable gas, and some parafine, with a few drops of water.

VOL. XXI. PART I. D

12 DR TRAILL ON THE TORBANEHILL MINERAL.

Composition.

A specimen of the darkest colour, from pit No. 3, afforded of—
Volatile matter = 84°1 per cent.
Solid residue =15°9 _,,
100 grains afforded 60°5 cubic inches of a dense inflammable gas.

Besides these, the quantity of paraffine appeared considerable.
The solid residue consisted chiefly of silica and alumina, with traces of lime,
and oxide of iron.

Geological Character.

It occurs in a bed, varying in thickness from 16 to 24 inches, in the coal for-
mation at Torbanehill and Boghead, in Linlithgowshire, in contact with shales and
clay ironstone, with an inclination of about 7°, dipping to the north. It occa-
sionally contains casts and impressions of large Stigmariz, and other fossil vege-
tables, which are also found in the accompanying shales.

Note.—Since the above paper was written, I have learnt that an important de-
cision of the question, “* Whether this mineral be, or be not, a coal?” has occurred
in Germany.

About the very time when the case of GILLEsPIE v. RUSSELL was tried in our
Courts, and a Jury decided that the Torbanehill mineral was @ coal, a directly
opposite opinion was pronounced by a more competent tribunal in Prussia.

It seems that in the imperial city of Frankfort there are two rival gas compa-
nies, one of which is restricted to the use of oil, or of resinous or bituminous sub-
stances; the other to coal alone, in the manufacture of gas for illumination.

The oil gas company imported the Linlithgow mineral, as a bituminous sub-
stance for gas-making; but they were opposed by the other company, as infring-
ing their exclusive right. Another question also arose between the first company
and the customhouse. By the laws of the German Zollverein, coal pays an im-
port duty of from one to two shillings per ton, while oil or resinous substances
used for gas-making may be imported duty free.

The city customhouse authorities were unable to decide the question ; and, as
in all such circumstances.of doubt, the case was referred to the determination of
the Central Board of Customs, which has its seat at Berlin. That board wisely
called in the assistance of the most eminent scientific men of the capital, among
whom were some of the distinguished Professors of the Berlin University: and
these united bodies have decided that the Linlithgowshire mineral may be im-

DR TRAILL ON THE TORBANEHILL MINERAL. 13

ported duty free, “for it is not a coa/, but must rather be classed with bituminous
shales.”

This decision of the General Zollverein Board is more worthy of notice, as it
is evidently against the interests of their customhouse union, since it allows a
foreign article to be imported duty free.

I am gratified by finding that the opinion which I gave six months before,
that the Torbanehill mineral is not a coal, has been confirmed by such authority.

I may be permitted to add, that though I readily allow its greater affinity to
bituminous shale than to coal, and had conjectured that it may have been formed
by the injection of bitumen into a shale, yet it differs in mineralogical characters
- from any bituminous shale I have seen, or is described in systems of mineralogy,
by being perfectly dull in every direction,—by entirely changing its colour in the
streak,—by being translucent on its thin edges,—by its higher inflammability,—
and by its lower specific gravity.

On these grounds I considered it an undescribed mineral, and ventured to
propose for it the name of BITUMENITE.

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I.—On a New Hygrometer or Dew Point Instrument. By A. ConnELL, Esq.,
F.R.S.E., Professor of Chemistry in the University of St Andrews.

(Read 3d April 1854.)

How convenient soever the wet bulb thermometer and the various organic
hygrometers may be for giving indications, by simple inspection, regarding the
relative states of dryness and humidity of the atmosphere, it is scarcely possible,
in conducting meteorological observations, to dispense altogether with instruments
calculated for affording more direct information respecting the amount of aqueous
vapour present in the air at any particular time.

The old methods of Le Roi, Saussurz, and Dauton, depending on the cooling
action of water or saline solutions on glass or metallic surfaces, are always avail-
able for that purpose; and some years ago I suggested an arrangement on the
same principle, consisting merely of a little bottle of polished brass, and a small
thermometer, into the former of which given measures of mixed nitre and sal-
ammoniac, and of water, were introduced, and the temperature slowly reduced
by simple agitation, so as to admit of an easy mode of noting the dew point by a
single operation.*

The elegant hygrometer of the late Professor DANIELL is sufficiently well
known. It is a happy application of the ingenious Cryophorus of Dr WoLuasTon.

I have now to submit to the notice of the Society an arrangement which has
occurred to me for determining the dew point; and I think it will be found that
this object may be accomplished by means of it, without much trouble. The me-
thod proposed has this in common with Mr DantELu’s, that it produces the cool-
ing effect on the observed surface by the volatilization of ether; but it entirely
differs from it as regards the manner of removing the obstacles to that volatiliza-
tion, and of keeping up the process of evaporation.

It is in no respect a cryophorus, but produces and maintains the necessary
rarefaction or vacuum, simply by the action of a small exhausting syringe. The
accompanying figure will explain the nature of the arrangement.

A is a little round bottle of thin brass, well polished on the outside, and capable
of holding, when filled to the bottom ofits neck, half an ounce of liquid. Its diame-
ter is about 154 inch. Its neck is 2 inch high, and about 3, inch wide, and flashed
out a little at top. The passage M, which conducts into the neck, has throughout
an internal diameter of 4 inch, and it is very essential that it should not be nar-
rower than this.

* See Edinburgh New Philosophical Journal for 1835.
VOL. XXI. PART I. E

16 PROFESSOR CONNELL ON A

B is a small mercurial thermometer, the bulb of which reaches within 4 of an
inch of the bottom of the bottle, and the upper part of the bulb is on a level with

the surface of the liquid contained in the bottle, or a little above that level. The
bulb ought not to be entirely immersed in the liquid. Its shape is an elongated
cylinder, about 3 inch in length, and about }in diameter. The thermometer has
a small scale attached to it, graduated according to both FanRENuETIT’s and CELsIus’
scales from 0° F. to 100° F. The stem of the thermometer is cemented at C into a
little brass stopper, fitted by grinding into the neck of the bottle, so as to be per-
fectly air-tight. DE is a small exhausting syringe of brass, the cylinder of which is
5 inches long, by about ; inch wide. It must effect its purpose of exhausting in as
perfect a manner as an instrument of that size can accomplish. FG isa clamp of
brass, capable of being attached by the screw horizontally to a window-sill in the
position which it occupies in the figure, or vertically to a common table, the holding
surfaces which come in contact with the body grasped being well roughened.
The syringe screws into this clamp at K by a projecting screw soldered to the
former, when the clamp is screwed to a window-sill, as in the case when an ob-
servation is made at an open window; or this projecting screw is inserted at L,
when the clamp is fastened to a table, as is done when the experiment is made in
a room. In both cases the syringe itself occupies a horizontal position, and
the bottle and thermometer, of course, a vertical one; the projecting screw K
should be so constructed as to cause the syringe to incline with the bottle a little
downwards, that the tendency of any ether to pass from the bottle into the

NEW HYGROMETER OR DEW POINT INSTRUMENT. Ee

syringe may be counteracted, and any trace of it which should pass or be con-
densed in the syringe shall run back into the bottle.

Let us suppose the instrument fixed at an open window on the sill. We, of
course, note the barometer and the temperature of the external air at the time;
and it is convenient, if a wet bulb thermometer happens to be at the window, to
observe the amount of the cold of evaporation at the time, because it gives an
idea of the point near which the dew point may be expected, although, of course,
such an observation is by no means essential.

A half-ounce measure, graduated into drams, is then filled with good commer-
cial sulphuric ether to the extent of three drams of the liquid. This is slowly
and carefully poured by a proper lip in the measure into the bottle, the other
hand being held so as to prevent any interference with this operation from any
draft or wind, and the thermometer is immediately inserted in the bottle, and
the stopper properly fixed. The process of exhaustion is then begun, at first
slowly, by working the piston by one of the fingers of the right hand, so as to
produce a gradual cooling agency and equable distribution of the effect; and
quickened somewhat as occasion may seem to require. In damp weather, the
working of the instrument can scarcely be too slow. One or two fingers of the
left hand are held on the upper part of the syringe, both to aid the holding of the
clamp, and to be ready to obviate the consequences of any accidental detachment.
When the cold of evaporation or other indications prepare us to expect a very
dry air, it is best to begin from the first with a pretty quick action of the piston,
so as to secure a good reduction, and there will be sufficient time for the spread-

ing of the effect over all the necessary parts. The thermometer will in all cases
be observed to begin to fall almost immediately ; and generally speaking, according
to the observations which I have now been carrying on in this place for three or
four months past, the deposition of dew may be first observed on the exterior sur-
face of the little brass bottle in from one minute to one and a half minutes.
Sometimes, of course, when the air is drier than usual, longer working will be
required, and when it is more moist, less time will be necessary. The screw
of the clamp usually requires to be occasionally a little tightened, during the first
part of the process of exhaustion.

My first essays, merely in the way of trial, were made with one of the large
syringes used in organic analysis, and a very few strokes of the piston were with it
found to be sufficient for the purpose. But asit was not only inexpedient that the
object should be so quickly accomplished, but so large an instrument would have
been deficient in portability, and inconvenient in other respects, I applied to Messrs
Kemp of Edinburgh to construct for me a syringe as small as they thought was
likely to accomplish the desired purpose. They at first sent one only 31 inches long.
This I found to be quite powerful enough for some cases, but not sufficiently so
for many which occur. I therefore had one made of the size described above.

18 PROFESSOR CONNELL ON A

This, during three months’ observations, I have found to be sufficient for general
use; but an extreme case occurring, when, after reducing the temperature be-
low 20°, no dew occurred, I thought of a method of increasing the effect without
having recourse to any augmentation of the size of the syringe. This was to have
a collar of ivory introduced between the little bottle and the syringe, so as to cut
off entirely metallic communication between them. The passage into the bottle
of the heat generated during the motion of the piston, would thus be pre-
vented, and the cold produced by the evaporation of the ether would be enabled
to take full effect. This idea was carried into execution, by constructing of ivory
the extremity N of the syringe carrying the terminal valve. The aperture
in the portion of this ivory piece to which the valve is attached is at least
75 inch in diameter, that of the remainder of it is 3. This ivory piece screws into
the brass passage which conducts into the neck of the bottle. Since this change
was effected, | have experienced little difficulty in producing the necessary
cold, even in a very dry atmosphere, and have obtained it even as low as 8 F.,
with the external air at 36°. There is one point, however, which requires atten-
tion in the use of this ivory valve-piece,—to avoid any considerable force either in
screwing or in unscrewing it, as its fracture is risked. Hence we ought to be
particularly on our guard against this screw getting jized, either by being over-
screwed, or by remaining too long unmoved. Indeed the safer way is, always
after using the instrument, to loosen this screw lightly, and leave it so till next
observation, and then tighten it again; and if it should happen to get fixed, to
wrap it round with cotton, moisten the cotton well with olive-oil, and leave it in
this state for a couple of days, when it will admit of being unscrewed without
injury. If necessary, a projecting screw of brass might be attached to the lateral
passage into the bottle, and fit into the ivory valve-piece.

At a much earlier period of the trial, a difficulty occurred as to the valves of
the syringe. These were at first constructed of the usual oiled silk. But it was
soon found that the ethereal vapour acted on them, and impaired their energy.
Vulcanized Indian-rubber was then tried, but, as might have been foreseen, from
the solvent action of ether on caoutchouc, this material, although it stood better
than the oiled silk, was also affected. I then thought that it would have been ne-
cessary to have had recourse to metallic valves, when Mr ALEXANDER KEMP sug-
gested the employment of goldbeaters’ leaf. This suggestion, contrary perhaps to
what might at first have been expected, has hitherto proved quite successful ; and
I have now been daily using, for three months, two syringes, the valves of which
are made of this substance, without any material diminution of their action.*

I had at first thought of holding the apparatus simply in the hand during its

* In constructing each valve, four folds of the leaf are employed. Should the valves become

impaired by use, they may easily be renewed, and the leather of the piston may also in time require
renewal also,

NEW HYGROMETER OR DEW POINT INSTRUMENT. 19

employment, but it was soon found that it could not be efficiently worked in this
way; that the same reduction of temperature could not be effected; that the
exertion was fatiguing; and that by the motion the thermometer was sometimes
broken. I now never think of using it, except when well secured by the clamp
to a fixture.

By this arrangement, during the winter, at an open window, I have reduced
the temperature of the ether in the little bottle, when I thought proper, from 20°
to 30° below the temperature of the air, which, so far as my observation has
reached, embraces all ordinary cases of dew point. In a room of the temperature
of 57°, I have effected a reduction of 42° below the temperature of the room; and
should it ever be thought that the reducing agency is not sufficient, we always
have it in our power to augment the energy of the process, by enlarging somewhat
the syringe, say to 53 or 6 inches in length, by ;} inch in diameter. This, I doubt
not, would give a considerable augmentation of power, and would not present an
inconveniently large instrument; but still I think it much better to continue it
at the size I formerly mentioned, unless more extended observation shall shew
the propriety of farther enlargement.*

The expenditure of ether during the exhaustion is very small; being on an ave-
rage about half a dram or less, value from a halfpenny to a farthing. With the dew
point only 5° or 6° below the temperature of the air, I have obtained the required
reduction with the expenditure of only 7, of a dram. When the observation is
completed, the residual ether is immediately poured back into a separate bottle
kept for the purpose, and well stopped; and it may be used again repeat-
edly, making it up each time to 3 drams, by adding fresh ether from another
bottle, in so far as necessary. I have used the same ether in this way for a week
or two ; but, of course, this should not be persevered in too long; and entirely fresh
ether should be employed after a certain time, and preserved as before, till no
longer proper for use. The inexperienced operator should also be warned, that, in
case of any night observations, any light employed should be kept at a distance
from the ether, which, from its extreme volatility and inflammability, is very apt
to take fire, unless this caution is used. It should farther be borne in mind, that
all commercial ether contains alcohol, which, of course, will not be soreadily vo-
latilized as the ether itself, and will accumulate in the residual liquid. After the
instrument has been used, and the residual ether poured back, it is expedient to
cause the instrument to lean against some support for a few minutes, with the
bottle in an inverted position ; and then to work the piston a few times backwards
and forwards, to expel residual ether or its vapour. The leather of the piston
should be rubbed from time to time with olive-oil, and care should be taken that

* Whilst revising the proof sheets of this paper in the month of June in London, I have had
opportunities of trying the instrument at higher temperatures at an open window; and with the
external thermometer at 68° have effected a reduction of 343°, the dew point being on one occasion
found to be 313° below the temperature of the air.

VOL. XXI. PART I. FE

20 PROFESSOR CONNELU ON A

the washers of the different screws do not become too dry. This is prevented by
the occasional use of olive-oil ; and this is one of the first things to be looked to,
at any time when the instrument may seem not to work well. It must of course
be remembered that the different parts of the instrument must not only be of the
best construction at first, but must be maintained in a fit condition, by constant
attention to the state of the valves, of the connecting screws, and of the piston, &c.

Every one must, of course, be allowed to make his observation as to the true point
of deposition, in the manner he thinks best; but I may be permitted to make a few
remarks explanatory of my own views upon the subject. It is well known that it has
been often objected to Mr DaNIeL’s instrument, that it gives the dew point too
high; and Mr Jounn Apig, by a comparison of its indications with those obtained by
Dauton’s method, found the error occasionally to amount to 63°, and on an average of
28 observations, to reach 2°-9. This is explained on the idea that the surface of the
ether, which is the seat of greatest cold, communicates the effect to the surround-
ing zone of the glass bulb of the hygrometer, before the bulb of the thermometer
has been cooled to the same extent by the liquid; that portion of the bulb above
the surface of the liquid itself, as well as that below it in the liquid, being sup-
posed to be at a higher temperature. It appears to me that the instrument de-
scribed in this paper will be much less liable to such an objection, because metal
being a much better conductor of heat than glass, it is hardly possible that the
cooling effect should accumulate in any one zone of the little brass ball, but must
be diffused over the whole without delay. Time is thus given for the frigorific in-
fluence being communicated to the whole bulb of the thermometer, both by the
evaporating surface, and by the body of the liquid itself, which principally yields
the latent heat required by the ethereal vapour. I have already stated that the
thermometer ought to be so placed as to have the upper part of its bulb in the
plane of the surface of the liquid, or a little above that position, and the rest of it
immersed in the fluid. These observations being premised, I conceive that the
great point, in the first instance, is to endeavour to mark the very first decided
deposit of moisture on the outside of the little bottle. I am aware that some
regard the point of disappearance of the dew, when the cooling process is stopped,
as giving better indication. I confess I do not concur in this idea, because a
little time must elapse before the air can take up again what it has already de-
posited; and if more than the very initial deposition has occurred, this taking up
will be still farther retarded, and the apparent point of deposition elevated
beyond the reality. This observation, of course, does not apply to Daron’s
method by transference, because each observation is isolated and complete in
itself. Most experimenters now, I believe, with ordinary dew point hygrometers,
take a mean of the two observations. This is perhaps the best mode of any, and
at all events is decidedly better than the disappearance alone ; and, accordingly,
it is the method which I have followed in making the observations with this

NEW HYGROMETER OR DEW POINT INSTRUMENT. 21

instrument, recorded in this paper, and which may be recommended to others.
The proper mode will be, first, to note the instant of decided appearance of mois-
ture, and mark the temperature indicated by the thermometer; then, to stop the
farther reduction the instant this decided deposition is observed; next, to mark
the instant of disappearance, and the corresponding temperature; and, lastly, to
take a mean of the two observed temperatures. In observing the point of appear-
ance, 1 notice the first apparent indication of moisture, and then see whether,
immediately on farther reduction of temperature, this indication becomes quite
distinct. I then take the former indication as marking the temperature of depo-
sition. In this way we can easily distinguish between a true and a false indica-
tion. Every one, however, as before observed, must be permitted to make his
observation in the manner which he thinks best.

Since this paper was first drawn up, I have made a series of observations, with
the view of comparing the indications of the instrument with those afforded both
by DaniELL’s hygrometer, and by Dauron’s method of transference, which last is
generally admitted to be the most trustworthy, although certainly very far from
being the least troublesome.* These observations have supported the view that
DaNIELL’s hygrometer yields indications somewhat too high, although not to
quite so great an extent as follows from Mr Apix’s observations. They shew that
the tendency of the instrument described in this paper is rather in the opposite
direction, and that its usual indications are a very little too low, but that this de-
viation is less on an average than 1°, and therefore quite within such limits as
fully to justify reliance on its results. The following table contains the observa-
tions; those by Dauron’s method being stated at the actually observed dew point,
and the others in excess or deficiency, with reference to DaLTon.

24.) 26.| 28.| 29.| 30.

1854, March} 11.} 12.) 13.) 14.| 15.) 16.| 17.| 18.| 19.] 20.] 21.) 22.| 28.

DALTON, .~ | 423) 373] 374) 403) 40 | 40 | 35 | 33 | 32 | 362) 34 | 42 | 354) 31 | 354) 3932] 45 | 43
DANIELL, . |—1 |+14/4+ 3 = |+24)/4+ 4-1 |+ H+ H+ H41-W+ H+ 2-2 |414/4+14/- FAverage +0°-29

New Instru-
ment,

=

+2|— aJ— 3] |=23)-22/-13|-2 |+ 4/—-2 |—23|- 3)-23|— 3|— g]+13|Average ~ 0°95

We thus have, in a series of observations of dew point temperatures, varying
from 32° to 45°, DaNreLL’s hygrometer, in eighteen observations, giving twelve of
them in excess or above the dew point by Datron’s method, five of them in de-
ficiency or below the point referred to, and one of them shewing equality. The
average of the whole, however, gives only 0°29 F. in excess. I cannot, however,
help saying, that when I got an observation by DantEtt in deficiency, and repeated

* In support of the great trustworthiness of Datron’s method, I may appeal to the opinion of
Protessor James Forzes, 2d Report on Meteorology to British Association, 1832; and to Dr Tuom-
SoNn’s opinion, there referred to. It is unnecessary to say that I had previously compared the ther-
™mometers, and that I made allowance in the comparative table drawn up, for a slight difference ob-
served in their indications.

22 PROFESSOR CONNELL ON A

it with every care, I then obtained a result in excess, and therefore am inclined
to think, that the tendency of that instrument is so decidedly in excess, although
certainly to only a small extent, that I doubt the perfect accuracy of any operation
with it in deficiency. I however retain the average, as observation gave it. With
regard to the instrument described in this paper, it affords, in sixteen observations,
thirteen results in deficiency with reference to the same standard, and three in
excess, the average of the whole being 0°-95 in deficiency.

These observations, I think, entitle me to ask that any one wishing to make
an experimental estimate of the value of the indications of this instrument, shall
not assume DaNniELL’s instrument as giving indications which can be rigidly con-
sidered as standards of comparison. It is by Dauron’s method that I should
wish it to be tried; and, I may mention, that in using this method I employed two
German becker glasses, 34 inches deep by 24 wide, and added a mixture of equal
parts of nitre and sal-ammoniac, in powder, to the water, till it shewed dew; and
then, by transference of the liquid from one to the other, carefully cleansing and
drying the surfaces, noted the point of disappearance of moisture, and took a mean
between that and the last observation shewing dew, provided the difference did not
exceed 1° or 14°; being satisfied that there were many more chances that the
true dew point lay in this interval, than at the first temperature at which no dew
was noticed. The difference, however, resulting from this mode of observation
in the noted result scarcely in any case exceeds 0°'5 F., and is usually much less.*

I think it preferable, on the whole, to leave the little bottle with its proper
brass surface duly polished, rather than to have it gilt ; at least I think that every
one will find this to be the case, who will take care always to have it preserved
quite bright and clean, which is easily done by the use, when necessary, of ordi-
nary brass polishing paste.t For those who would wish to have it always in a
state fit for use, with little or no trouble, although at the cost of a little polish of
surface, it will be best to have the surface gilt. Although not quite so delicate in
its indications, it will be sufficiently so for use. This is a matter which may be
safely left to the option of individuals. Possibly a bottle of polished silver might,
on the whole, be better than either, but I do not think it likely that any advan-
tage in this way would be worth the additional expense. This method is, how-
ever, open to any one who wishes it.

* T occasionally noticed that after adding the salts, the jirst deposition of moisture could not
be noticed before the surface of the glass had imperceptibly become quite moist, and the temperature
much below the true dew point; but this, of course, was easily corrected, by transferring the liquid to
a dry vessel, and proceeding in the usual way.

+ The manner recommended to me is to scrape off with a knife from. a piece of good and light
rotten-stone, some very fine powder, to place this on a piece of woollen cloth, such as the rind of
broad cloth, to mix this with a little olive-oil, and rub the bottle with this mixture, then to rub it with
a piece of cotton cloth, on which a little of the fine powdered rotten-stone has been laid, and to finish
by rubbing with a piece of soft cloth, without either powder or oil, till a bright surface is obtained.
A piece of chamois leather is also kept with which to clean it, when the paste is not used.

NEW HYGROMETER OR DEW POINT INSTRUMENT. 23

In the use of the instrument, a little dexterity of manipulation will of course
be necessary, but this will easily be attained by practice, and the necessary care.
Success will entirely depend on minute attention being paid to the various parti-
culars which have been mentioned ; on the perfection of construction of the syringe
and of its valves; on the various connections being quite air-tight; and on the
steadiness and security of the clamp employed.* <A point apparently unnecessary
to be noticed, although really very essential and very apt to be overlooked, is that
the internal diameter of the passage M, connecting the syringe with the bottle, shall
throughout not be less than 4 inch.

After I had had the apparatus constructed, I made a search through various
books, with the view of discovering whether any similar idea had occurred to any
one else. The only instances I could find, which would admit any supposition of
resemblance, were in the cases of two hygrometers, the one contrived by Dosr-
REINER, and described in GitBERT’s Annalen der Physik+ for 1822; and the other
by Dr Cummine of Chester, of which an account is given in the Second Part of
the Article Thermometer and Pyrometer, of the Library of Useful Knowledge.
Both these instruments differ, however, essentially from mine, not only in arrange-
ments, but in principle. They agree with Professor DanreLt’s and with mine, in.
producing the necessary cold, by the evaporation of ether; but they produce the
evaporation in quite a different way and on a different principle from either, viz.,
by blowing a current of air through the ether, and so producing and maintaining
its volatilization. They use a syringe for this purpose, but it is not an exhausting
syringe, it is a condensing one. They create no vacuum of air; on the contrary,
they increase the amount of it present. In DoBEREINER’s, also, there is a rather
complicated series of valves between the condensing syringe and the metallic
tube, which contains the ether. Both instruments may possibly answer their end,
bat they differ entirely both from DanieLu’s and from mine. It is only since
the paper was given in to the Royal Society, that I noticed in Ganot’s Traité
de Physique, an account of Reanavuut’s hygrometer, which effects the reduction
of temperature on a similar principle to the two just mentioned, by passing
through ether a current of air, which is set in motion by means of what chemists
call an Aspirator, 7.¢., a large gas holder containing air from which there is a flow
of water.

My experiments with the instrument have as yet all been made in winter, or
early spring, but I do not anticipate any additional difficulty in summer. Indeed
the higher temperature will be favourable to the exhaustion, and consequent cold,
and in such experiments as those made in a warm room, I have found the results
quite satisfactory. See also note, p. 9,

* As window sills are often inclined and uneven, one or two little wedges of wood may be
employed to produce steadiness of attachment. Pieces of wood may be used to prevent fine tables
from receiving injury, in attaching the clamp to them.

+ Zehnterband, s. 135.

VOL. XXI. PART I. G

24 PROFESSOR CONNELL ON A

When the air is very moist, and there is little difference between the tem-
perature of the air and the point of deposition of moisture, care may be taken
that the ether shall have a temperature some degrees above that of the air,
which will be effected by holding the hand for a little on the brass bottle
after the ether has been introduced into it, or by employing any other means
likely to accomplish this object.

If an observation should at any time be made entirely out of doors, all that
will be necessary will be to have some fixture attached to a tree or gate-post, or
inserted in the ground, to which the clamp may be secured.

Messrs Kemp have undertaken to prepare the apparatus with clamp, bottles
for ether, &c. &c., packed conveniently in a small portable case; and any one
who may procure it from them, or from any other instrument-maker, ought, of
course, to take care that all the particulars mentioned in the foregoing observa-
tions are rigidly complied with. Insufficient or careless workmanship is quite
incompatible with success ; and as already stated, it is not only necessary that
the instrument shall be of extremely good construction at first, but that it shall
be preserved in that state, in all points. In its present state it may seem very
simple, as I am happy to say it really is, but still the result was not attained
without much consideration regarding minute particulars on my own part, and
skill and dexterity on the part of the artificers. It is with the view of enabling
others to construct the instrument efficiently, as well as to think of remedies
for any other difficulties which may occur, that I have allowed myself to indulge
in so much narrative and detail of particulars.

I think that it may be found that the instrument will have the advantage of
being little liable to accident in travelling, and the thermometer is very securely
packed in a proper case.

I should be very sorry to have it thought, that in any observations which I
have made regarding Mr DaniELL’s hygrometer, I should be supposed to speak
in the slightest degree in a tone of disparagement of that instrument. On the
contrary, I think that I have shewn that, with a slight allowance, it is perfectly
trustworthy; and I firmly believe that so beautiful and philosophical an instru-
ment will never be entirely superseded. If that which I have described shall
ever be thought to have an advantage over it in any respect, it will, I think, be
on the score of little tendency to injury, and probably to greater facility of obser-
vation, after a little dexterity of manipulation has been acquired by practice.
There is undoubtedly an occasional difficulty in noting the results by DaNniIELL’s
instrument. I must, however, take the liberty of repeating my protest against
a view which I fear there is ground for thinking some English meteorologists
have quite made up their minds to adopt, that the indications of DAnreL’s hy-
erometer are quite accurate, and ought to be taken as the general standard of com-
parison, according to which the accuracy of all other dew point instruments, and

NEW HYGROMETER OR DEW POINT INSTRUMENT. 25

of all dew point formule and tables of factors is to be determined. The grounds
of my dissent from such a view have been already given.

There is a slight modification of the manner of applying the ivory intercepting
portion, by placing it as an ivory collar in the neck of the bottle at the point
P, instead of at N, as formerly described. It ought to be $ of an inch broad. In
this case the valve piece N is of brass, so that the risk of its accidental fracture, in
screwing or unscrewing, is avoided, but in these operations the ivory portion of
the neck of the bottle should not be grasped. I am not yet, however, prepared to
recommend either of these modifications in preference to the other. Both, gene-
rally speaking, answer perfectly well.

Sr ANDREWS, 25th February 1854.

Postscript.—After the paper was read at the meeting of the Royal Society, I
was asked by a gentleman present, whether the instrument would answer for an
Indian climate, where extreme cases of great dryness of atmosphere sometimes
occur? I, of course, answered that I had had no opportunity of making experi-
ments under such circumstances as an Indian climate might occasionally present ;
but that if the present size of the syringe was found not to render it sufficiently
powerful for such extreme cases, I had little doubt that by some such increase
of the size of the syringe as formerly suggested, the necessary augmentation of
power might be attained. I may add, that in the event of the occurrence of very
extreme cases, where all ordinary hygrometers might fail to give the necessary
indication, the object, there is little doubt, might be accomplished, by means. of
the arrangement which I suggested several years ago, as mentioned in the com-
mencement of this paper, employing instead of a bottle of brass, one of thin glass,
or still better, of platinum, somewhat larger than that described in the notice re-
ferred to, and introducing into it'some mixture capable of producing great cold.
One of phosphate of soda, nitrate of ammonia, and diluted nitric acid, is capable
of reducing the temperature from 50° to— 20°; and from higher temperatures
would produce a proportional reduction ; and if pounded ice with the proper acid
were used, still greater cold would result.

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Cari

IV.—On the Action of the Halogen Compounds of Ethyl and Anyl on some Vegetable
Alkaloids. By My Henry How, Assistant to Professor ANDERSON, Glasgow
University.

(Read 1st May 1854.)

Tue memoir which I have now the honour of presenting to the Society contains
part of a continued investigation, of which the first results were published
in a paper read, last year, before the Chemical Society of London.* The nature
of the materials experimented on is such, and the scope of the subject so large,
as to afford nothing more to all I have at present brought to light than the name
of abareand partial outline; yet the facts I have now to adduce, of some interest
in themselves, will increase that of those already made known, and prove of addi-
tional service in aiding to complete that desirable object, a knowledge of the che-
mical constitution of the natural bases. In the paper alluded to, I shewed that,.
by the action of iodide of ethyl and of methyl upon morphia and codeine, the two
most prominent alkaloids of opium, new salts are produced, in which the basic
molecules appear to assimilate by their chemical characters to the hypothetical
metal ammonium, or its oxide rather; so that, in the system of Hormann, these
peculiar results of natural, and as yet inimitable agencies, would take rank among
the nitryle bases. I say as yet inimitable, because it appeared that although one
of the new salts possessed precisely the same centesimal composition as the cor-
responding salt of codeine, the base contained in the artificial product was widely
different in appearance and properties from this alkaloid; a fact which seems to
militate against a hope of forming the natural bases by this or similar means, and
to show that the building up of these bodies is a process peculiarly the function
of the vis vite of the plants producing them; at least that, easy as the transition
of morphia into codeine appears to be on a comparison of their respective rational
formulse, and since the adding the required two equivalents of carbon and hydro-
gen to the former proves of ready performance, the cause of the failure lies deeper
than in this difference merely, and that there are peculiarities in the construction of
the primary molecules which we are at present as far as ever from being able to imi-
tate. I further remarked, that so far as the amount of basic hydrogen, or com-
pounds supplying its place, is concerned, the fact that it proved the same in these
two alkaloids was possibly to be anticipated from their similar origin; and that I
intended pursuing the subject with a view of ascertaining if all the bases of the
same plant were so far analogous. It will be seen that they do not appear to be

* Quart. Journ, Chem. Soc, vol. vi.
VOL. XXI. PART I. H

28 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

so in reality, my attempts at forming corresponding compounds with some other
alkaline principles of opium having been as yet unsuccessful. Another order of
plants, however, has furnished me a base, strychnine, which seems in this respect
similarly constituted with morphia and codeine, inasmuch as, under the same
circumstances, it yielded a new combination, whose stability in the free state, and
in some of its salts, caused it to afford more decided results than I was able to
obtain with the analogous products from these alkaloids.

This investigation was pursued in the laboratory of Professor ANDERSON, in
the University of Glasgow, to whom my cordial thanks are due for the interest
he took in its progress, and, among other things, for the facilities he afforded me
in placing at my disposal specimens of subjects for experiment.

In describing the individual re-actions, salts, &c., I have preferred giving them,
as nearly as is consistent with clearness, in the order in which they were inves-
tigated.

Behaviour of Papaverine with Iodide of Ethyl.

Hydriodate of Papaverine.—Next to morphia and codeine, papaverine is the
opium alkaloid possessing the most marked characters, and highly basic properties,
and as I was acquainted with the beautiful substitution products it yielded to
Professor ANDERSON, of which an account has been given to this Society,* I chose
it as the subject for further experiment. Accordingly, some of the base, in small
crystals, was placed in a tube, spirit of wine poured on it, and iodide of ethyl
added ; a great part of the crystals was seen to disappear immediately, and when
the sealed tube was placed in boiling water, solution became rapidly complete.
The clear fluid was allowed to boil about half an hour, but no solid made its ap-
pearance, either during the continuance of the heat, or upon the subsequent cool-
ing and standing of the vessel. The solution was distilled finally in a flask to a
very small bulk, and the syrup which remained soon solidified into a crystalline
mass; this was found to be perfectly soluble in hot water—papaverine itself being
insoluble—and in spirit of wine; but, from peculiarities to be mentioned presently,
absolute alcohol was preferred as a solvent. From a concentrated hot solution
in this menstruum, the new product was obtained, on cooling, in rhombic crystals,
a portion of which, as they proved to be an hydriodate, was submitted to ana-
lysis in the ordinary way, with the following result :—

5°558 grains, dried in vacuo, gave
2°780 ... iodide of silver,

which gives a percentage of iodine of 27:02, and 27:21 is the theoretical calcula-
tion corresponding to the anhydrous hydriodate of papaverine, whose formula is
C,, H,, NO, HI.

* Trans. Roy. Soc. Hdin., vol. xxi., part i.

ON SOME VEGETABLE ALKALOIDS. 29

I shall shew presently, from an analysis and description of the base obtained
from this salt, that there can be no doubt of its real nature; so that, under these
circumstances, papaverine behaves in a manner similar to that shewn before* to
be the case when hydrated morphia is placed in contact with chloride of amyl, it
forms a salt, namely, with the halogen of the ether compound, while no doubt the
corresponding alcohol is simultaneously generated by the agency of the elements
of water, as in the equation—

C,, H,, NO, +0, H, 1+2HO=C,, H,, NO, HI+C, H, 0, ;

this, at least, seems the most obvious explanation of the change when water is
present. To determine if the formation of the salt were really due to the agency
of water, I repeated the experiment with absolute alcohol in place of rectified
spirit, and the papaverine was dried at 212°, to remove accidental moisture, its
crystals containing no water of combination. In this case, also, the hydriodate
was formed from part of the alkaloid, the rest remaining unaltered. The iodide
of ethyl had been distilled from chloride of calcium, and 1 should think could
furnish, at the most, but a minute quantity of water ; and it is not easy to see how
the reaction is brought about under these circumstances, unless it be assumed —
that it occurs with the formation of ether. The detection of this substance would
not be readily effected upon the small scale upon which I worked, and I there-
fore only throw out the following equation as a possible explanation of the re-
action—

C,, H,, NO,+C, H,1+C, H, 0,=C,, H,, NO, HI1+2 C, H, 0.

As no account has yet been given of the hydriodate of papaverine, a short
description of it may be subjoined. The salt is extremely soluble in boiling
water, and the moment the heat is withdrawn from a strong solution, the fluid
assumes a milky appearance, and an oil is soon deposited, which, after some
hours, passes into the form of stellate colourless needles; it is also soluble in
spirits of wine, but in absolute alcohol it dissolves with far less facility, and it re-
quires protracted boiling, when the salt has once taken on the crystalline condi-
tion, to obtain perfect solution with this menstruum. The hot liquid deposits the
salt rapidly, as it cools, in colourless rhombic crystals. When exposed to a tem-
perature of 212° Fahrenheit, in a dry state, the hydriodate of papaverine assumes
a brown tint, loses slightly in weight, and is found to have undergone some de-
composition, as it no longer dissolves completely in hot water, but leaves a brown
resinous matter.

By addition of ammonia to the mother liquors of the salt which had been
analysed, a white crystalline precipitate was obtained; this was recrystallized
from dilute spirit, and burnt with chromate of lead :—

* Quart. Journ. Chem. Soc., vol. vi.

30 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

3°552 grains, dried at 212°, gave

9:200 ,, carbonic acid, and

2-095 5, | Water.

Experiment. Calculation.
Carbon, - ; 70°63 70-79 G,., 240
Hydrogen, . - 6°55 6-20 ee 21
Nitrogen, : . 4:10 N 14
Oxygen, : ; 18°91 0, 64
100-00 100-00 339

A glance at the result, and the appended calculation of the numbers required by
the formula of papaverine, leaves no doubt as to the base of the salt. I was per-
fectly satisfied as to its nature, from its appearance and some peculiar well
marked reactions characteristic of papaverine; thus, with strong sulphuric acid
it yielded a splendid purple fluid, at the instant of solution, and when heated
with a little nitric acid, became converted into a mass of yellow crystals, which
are nitrate of nitropapaverine, described by Dr ANDERSON.*

Behaviour of Narcotine with Iodide of Ethyl.

Hydriodate of Narcotine.—The next alkaloid of opium submitted to examina-
tion was narcotine; and the following experiment shews its deportment to be per-
fectly similar to that of papaverine.

Some narcotine in fine powder was heated in a sealed tube with absolute
alcohol and iodide of ethyl; after about ten minutes exposure to a temperature
of 212°, the whole of the base disappeared; but to insure complete decomposition,
the heat was continued some twenty minutes longer. When the tube had cooled,
and stood a short time, groups of four-sided colourless prisms appeared. On
opening the vessel, and submitting these to examination, they proved to be un-
changed narcotine, while their mother liquor was found to contain an hydriodate.
The excess of iodide of ethyl and alcohol was accordingly distilled off, and the re-
maining syrup tested as to its nature; it was almost entirely soluble in boiling
water. leaving only a little narcotine, and the solution contained the hydrio-
date of that base.

This salt is deposited, from a concentrated fluid, as an oil which does not become
crystalline, and when its solution is evaporated, spontaneously or at 212°, an oily
mass is also obtained, which does not crystallize from alcohol, or ether, or a
mixture of these substances. Owing to its occurring only in this amorphous
state, I did not attempt to submit it to analysis; but its solution yielded to
ammonia a precipitate easily to be recognised as narcotine, by its characters and
chemical reactions; and in order fully to substantiate the nature of the base,
the hydriodate was converted into a platinum salt in the following manner :—

* Loc. cit.

ON SOME VEGETABLE ALKALOIDS. 31

An aqueous solution was treated successively with nitrate of silver and hydro-
chloric acid, and bichloride of platinum was finally added to the clear fluid, care
being taken to operate with dilute liquids and in the cold, as the platinum com-
pound of narcotine is very prone to change. An amorphous yellow precipitate
resulted, which was quickly collected, washed, and dried; it gave these numbers
on ignition,—

{1383 grains, dried at 212°, gave
1:330 =, ~—_——platinum.
which lead to a percentage of 15°88; and 15°81 is that required by the salt of
narcotine, whose formula is

C,, H,; NO,,, Hl, Pt Cl,.

14”

To the nature of the reaction in this case, I would apply the remarks
made with reference to papaverine under similar circumstances; but, perhaps,
should not permit the subject to pass without drawing attention to the relation
my experiment may bear to a fact made known some time since by WERTHEIM.

This chemist announced, in a preliminary notice,* that he had detected in
opium two new species of “narcotine,” which, from their composition, he named
methylo and propylo-narcotine, while he was led to consider the ordinary alkaloid,
hitherto known, as ethylonarcotine: the whole being derived from one fundamen-
tal substance. Ido not think the detailed account of his experiments has yet
been published, but it would certainly be interesting to establish the existence of
this series in reality, because, in that case, the ordinary narcotine, with which [|
worked, would seem to have no longer any replaceable hydrogen, and be the first
instance of a natural, or indeed of any compound nitrogenous analogue of ammo-
nium or a metal, unless papaverine be similarly constituted. In the absence of
positive proofs, resulting from experiment, nothing can at present be said further
as to the nature of these known and unknown bases; but the question seems to
me very interesting and worthy of being settled decisively, WERTHEIM’s being an
unsupported statement, particularly as, chemically, there is nothing to distinguish
narcotine and papaverine from other natural alkaloids, as a class, or to assi-
milate them to ammonium.

Behaviour of Cotarnine with Iodide of Ethyl.

Hydriodate of Cotarnine.—Cotarnine is a base derived from narcotine by oxi-
dation; some of it was treated exactly in the manner just described. It was found to
be completely converted into an hydriodate, which remained, on distilling off the
excess of alcohol and iodide of ethyl, as a red-brown oily mass, highly soluble in
hot, insoluble in cold, water, and not taking on the crystalline state under any cir-
cumstances. This salt was the hydriodate of cotarnine ; but being of itselfno more

* Journal fiir Praktische Chemie, vol. liii., p. 431; Chem. Gazette, 1852, p. 36.
VOL. XXI. PART I. I

32 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

fit for analysis than that of narcotine, the composition of the base was ascertained
by converting it into a platinum compound, which was a very pale yellow amor-
phous substance, and gave the following result on analysis :—

3-265 grains, dried at 212°, gave
0-720 ,, platinum,

equal to a percentage of 22°38; 22°57 corresponds to the formula of the cotar-
nine salt,

C,, H,, NO,, HCl, Pt Cl,.

This artificial product then comports itself exactly like the alkaloids papave-
rine and narcotine; and the reaction is no doubt of the same nature.

The formation of these salts of the alkaloids, in cases where water is present,
is possibly brought about by a change, observed by FRANKLAND* to take place
between iodide of ethyl and water in a sealed tube at 300° Fahr.; the results
of this reaction are, according tc this chemist, hydriodic acid and ether. It seems
not improbable that the presence of a basic substance may determine this decom-
position at a much lower temperature.

On Strychnine.

Having examined the action of the alcohol iodides on a number of bases with
only one equivalent of nitrogen, I was anxious to ascertain the deportment of a
base containing, like strychnine, two atoms of this element, in the hope of throw-
ing some light on the function of the second equivalent. The researches of
Hofmann, on a great variety of alkaloids, have shewn us that the volatile bases
starting from the original type ammonia, and passing upwards to the most com-
plicated substances, may be viewed as nitrogen attached to basic hydrogen
alone, or to it in combination with hydrocarbons performing its functions,
or finally to hydrocarbons occupying the entire hydrogen part of the molecule.
In the fixed vegetable alkaloids, we see oxygen also included in the system ;
and if, as I have attempted to prove in the case of some of these, they
are comparable with nitryle bases, the hydrogen part of the compounds must
contain oxygenized hydrocarbons acting as hydrogen. In the case of a base
containing two atoms of nitrogen, it is possible that this element performs as it
were two parts; one may be referable to the function of that in any ammonia,
amidogen, or nitryle base, while the other may be more analogous to that property
in virtue of which, in combination with oxygen, as NO,, it replaces an atom of
hydrogen in the carbohydregen forming part of the compound molecule. The

* Gerhardt Suite de Berzelius, 11., p. 323.

ON SOME VEGETABLE ALKALOIDS. 33

possibility of the latter being the case, as regards one of the atoms of nitrogen in
an alkaloid containing two, was thrown out as a speculative suggestion some few
years ago by FresEnIvs.

In the hope of arriving at some conclusions regarding these points, I proceeded
to examine the deportment of strychnine with reagents suited to my purpose.
The decision of the whole question seems to devolve upon the reactions of two
classes of agents ; the amount of basic hydrogen would be learned by the quantity
of hydrocarbons of alcohol radicals the base is capable of taking up from their
halogen compounds, while reducing agents should remove oxygen from any oxi-
dized combination of nitrogen; if it be as NO,, that the second atom of this ele-
ment exists, sulphuretted hydrogen should, as in other compounds of this class,
remove the four equivalents of oxygen, and permit two additional atoms of
hydrogen to enter into the new product.

The first part of the question is gone into in some detail in the present memoir,
while, without being in a position to give anything decisive at present with regard
to the second, I may mention that strychnine undergoes a curious decomposition in
contact with sulphide of ammonium, which results in the formation of hyposulphite
of the base itself,—a very beautiful and stable salt,—and the production of another
substance I am still engaged in studying. ‘The description of the properties and
composition of these products I must reserve till Iam able to shew the complete
history of the change, and how far the real constitution of strychnine is deter-
mined by the experiments; hut I may state that, from what I have as yet
learned, the decomposition does not appear to be of the nature just spoken of.

Action of Iodide of Ethyl on Strychnine.

Hydriodate of Ethylostrychnine.—Strychnine, in a state of fine powder, is
readily attacked by iodide of ethyl; even when these two substances are boiled
together in water, a perceptible quantity of iodine is found in the solution, preci-
pitable by silver salts; the insolubility of the alkaloid, however, no doubt inter-
feres with the reaction, for the change is much more easily effected when spirit
of wine is used asamedium. The most successful method I found to be that em-
ployed before, viz., to operate with alcohol and iodide of ethyl on the powdered
base in sealed tubes; at the temperature of boiling water the change is complete
in about twenty minutes. A heavy crystalline powder is formed, differing in ap-
pearance from strychnine; but solution is not at any time during the experiment
complete, no change being perceptible beyond the more definitely crystallized
nature of the solid contents of the tube, the complete solubility of which in boil-
ing water announces the completion of the reaction.

A boiling aqueous solution of the new substance having deposited, upon cool-
ing, masses of silky white crystals, which proved to consist of an hydriodate, they

34 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

were collected, washed, and dried, and a portion of them was submitted to ana-
lysis in the ordinary way.

( 4°325 grains, dried at 212”, gave

| 8:925 ,, carbonic acid, and
{4 2:180 ,, water.
4565 ,, dried at 212°, gave
2:195 ,, iodide of silver.
Experiment. Calculation.
SSS.
Carbon, .. ; : 56:27 56°31 C. 276
Hydrogen, ; : 5°60 5°50 i: a
Nitrogen, . ‘ , 5°71 N, 28
Oxygen, . : ; 6°55 OF 32
Iodine, . ; . 25°98 25:93 if t27770
100-00 100-00 490-1

A comparison of the above results and appended calculation will shew that a re-
placement of hydrogen by ethyl in, or an attachment of iodide of ethyl to, the
alkaloid has taken place, according to the equation,

C,, H,, N, 0,+C, H; I=C,, { ott \y, 0, HI=C,, H,, N, 0, I.
TInnStiee | 1 2 ee

Strychnine. New Salt.
The salt crystallizes without water, and whatever constitution subsequent experi-
ment may assign to it, it will be now described as an hydriodate, and its base as
ethylostrychnine.

Hydriodate of ethylostrychnine is soluble in about 50 or 60 parts boiling
water, and in about 170 of water at 60°; a tolerably dilute fluid deposits the salt
in very fine white four-sided prisms of considerable lustre, which they retain in
the dry state; it is also soluble in rectified spirit, and comes out of that menstruum
in short prismatic crystals. It is unaltered in the air; at 212° it loses no weight,
but acquires a slight shade of colour; at a higher temperature it fuses and
blackens, affording thick vapours of an alkaline reaction, and disagreeable odour ;
and a yellowish sublimate, rather oily in appearance, forms on the sides of
the vessel ; no vapours of iodine are to be observed during the process of heating.

This salt gives no base with potass or ammonia, but is less soluble in these
alkaline fluids than in water, and is consequently precipitated, on their addition,
in strong solutions ; strong potass throws it down at once in the cold, and when
ammonia is added to a concentrated boiling aqueous solution, the unchanged
salt deposits immediately in fine needles. It is readily decomposed by oxide
of silver, and the hydrated base may be obtained in the crystalline state. These
reactions assimilate the salt to an iodide rather than to an hydriodate, and the
characters of the base, when isolated as far as it can be, being those of an
analogue of ammonium oxide, its salts would perhaps be more correctly called

ON SOME VEGETABLE ALKALOIDS. | 35

iodide, chloride, &c.;.and in the following pages I make use of these terms,
without, however, making any alteration in the conventional nomenclature for
the base.

The salts of ethylostrychnine, generally, are characterized by their beautifully
crystalline nature, and the facility with which they may be obtained pure. Ihave
analysed a few, as affording a favourable opportunity of examining the combina-
tions of one of these derivatives from a natural fixed alkaloid.

Mitrate of Ethylostrychnine.—This compound is readily formed by double de-
composition from the preceding, by use of nitrate of silver in warm dilute solutions.
It is easily soluble in boiling water, but of extremely sparing solubility in this
menstruum when cold ; so much so, that I have used this property as a test of the
existence of the base on many occasions; a solution containing it, even when
tolerably dilute, depositing, on the addition of a little nitric acid, in a short time,
very fine four-sided prismatic crystals ; in more concentrated fluids their appear-
ance is immediate. ‘The salt, in a pure state, is in colourless prisms of high re-
fractive power, which may be obtained of great beauty from dilute aqueous fluids.
Its analysis gave the following results :—

4-555 grains, dried at 212°, gave
10-790 ... carbonic acid, and
2°680 ... water.
Found. Calculation.
——————
Carbon, . . . 64:60 G494-0C,. 276
Hydrogen, . . 6°53 630) Ey = 27
Nitrogen, . . °° 9°88 N, 42
Oxygen. G02). 133,807, 80
100-00 100-00 425

which agree precisely with the formula—
C,H, N, 07,30, NO, = C,, MM, N, 0, NO,.

Its crystals contain no water.

Chromates of Ethylostrychnine.—Both neutral and acid chromate of potass
yield precipitates w ith salts of the base; the former giving, even in dilute fluids,
short prismatic yellow crystals, and the latter tufts of silky needles. As the
number of bichromates, of whose analysis we are in possession, is in reality very
small, being limited, I believe, to those of potass and ammonia, whose constitu-
tion is peculiar, I examined the salt in the present instance, to see if it were quite
analogous to these compounds, which it does not appear to be.

Bichromate of ethylostrychnine is deposited from strong mixed solutions of the
appropriate salts in very beautiful transparent plates of a golden yellow colour;
it falls, as just mentioned, from more dilute fluids, in tufts of needles ; it is readily

VOL, XXI. PART. I. K

36 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL |

soluble in boiling water, but when cold, this liquid dissolves but little of the salt.
The following is the analysis :—

5173 = dried at 212°, gave

10840 carbonic acid, and
1. 2-755 .,. water.
5885 ... dried at 212°, gave, on ignition,
0°938 ... sesquioxide of chromium.
4-480 ++. dried at 212°, when ignited, gave
se { 0°715 ... sesquioxide of chromium.
Experiment. Calculation.
a a aOS—————— $$
ce I.
Carbon; 5 ./'., ... Bieue ST Baie . 276
Hydrogen, ©)... 5°91 561 Hi, 28
Nitrogen; 7.) ies S61 ..« iN, 28
ORVREs 3 ah os te os 29:99 O, 48
Chromic acid,. . . 20°86 20-88 21-06 2(Cr0,) 101-4
100-00 100-00 100-00 481-4

which gives results according satisfactorily with a formula which contains an
atom of water more than those of the corresponding potass and ammonia salts,
and may be thus written :-—

C,, H,, N, 0, HO, CrO,, HO CrO, = C,, H,, N, 0, CrO,, H Cr0,.

The failure of the analogy here, with the peculiar combinations of potass and
ammonia, is worthy of attention ; of course, it readily admits of explanation, if
the one atom of water be assumed as retained from the water of crystallization

of the new salt. The loss sustained by exposing the crystals to heat was as
follows :—

‘ 4-660 grains, lost at 212°,
“} O60... water

11°510 .... lost at 212°,
i 0:-435 ... water
I. II.

Percentage of water, 3°43 3°77

and 3°60 is the calculated percentage corresponding to a loss of two atoms of
water by a salt of the formula,—

C glo, N, O, COG, H CrOy 4 2 ag:

Platinum Sali of Ethylostrychnine.—By the successive addition of nitrate of
silver and hydrochloric acid to a warm solution of the iodide, and that of bi-
chloride of platinum to the clear fluid, this salt fell as a curdy yellow precipitate,
which became crystalline after some hours; from more dilute liquids it crystallizes
at once in a very beautiful form, namely, in groups of stars, of which the individual

ON SOME VEGETABLE ALKALOIDS. oC

rays resemble, on being magnified, the fronds of some species of ferns. ‘The plati-
nui alone, in this compound, was determined,—

3°390 grains, dried at 212°, gave
0-592 .-. platinum,

The percentage resulting from this experiment is 17°46; and 17:37 is that cor-
responding with the formula,—

C,, H,, N, 0, Cl, Pt Cl,.

The salt is anhydrous when crystallized.

The substitution of terchloride of gold for the platinum solution gives, by the
same process, a yellowish curdy precipitate, soluble in boiling water; and this
fluid deposits colourless brilliant prisms of splendid appearance, of the corre-
sponding gold compound.

The chloride is a very soluble salt, crystallizing in needles ; the sulphate is less
soluble, an acid fluid furnishing groups of pearly needles and plates, possibly a
bisulphate; the oxalate, prepared in a similar manner, has much the same appear-
ance; the acetate remains as a gummy transparent mass when a proper solution.
is evaporated to dryness at 212°; the chloride gives, with mercuric chloride, a
curdy white precipitate, crystallizable from hot water in white needles.

Carbonates of Ethylostruchnine.—Having observed, in the course of experiments
to be detailed presently, which were made for the purpose of obtaining the ethylo-
strychnine in an isolated state for analysis, the tendency of the base, when free
and in solution, to absorb carbonic acid, it occurred to me to attempt the pro-
duction of any carbonates of determinate composition it might be capable of form-
ing. I shall be able to shew that the base enters readily into combination with
this acid, forming at least two salts, of which while the one, the monocarbonate,
cannot be obtained in the dry state, the other, a bicarbonate,—into which, with the
occurrence of some other product of decomposition, the first appears to have a
great tendency to pass,—may be readily procured in the solid form, of determinate
composition, and even as a very beautiful crystalline substance.

It was found that when moist carbonate of silver is added to iodide of ethylo-
strychnine, covered with a little water. double decomposition ensues, and is com-
plete in a few minutes, when the vessel containing the mixture is well shaken ;
iodide of silver, of course, remaining undissolved, while the fluid contains a carbo-
nate of extreme solubility. When, without employing heat, the process is quickly
performed, so as to occupy only a few minutes of time, a perfectly colourless liquid
is obtained ; but with a longer contact of the excess of carbonate of silver, or the ap-
plication of heat, the fluid assumes a light claret colour, which, by the continued
action of either of the above causes, may be deepened almost indefinitely, and
seems to be the result of oxidation. This solution shews all the characters of a

38 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

carbonate in its reactions, and when saturated with dilute nitric acid, becomes
filled, almost before the cessation of effervescence, with the characteristic crystals
of the nitrate of ethylostrychnine ; when evaporated to dryness, however, either
in vacuo or at 212° Fahr., it is found to have undergone a singular decomposition.
The residue obtained in both cases is crystalline, and in part colourless, with claret-
coloured spots pervading its mass; on adding water to this, the great bulk dis-
solves to a deep claret-coloured fluid, which contains carbonic acid and ethylo-
strychnine, while an amorphous substance, in whitish flocks, remains in appre-
ciable quantity.

It is obvious that, with the observation of this decomposition, all hope of ana-
lysing the expected residue of pure monocarbonate of ethylostrychnine was at an
end; nevertheless, as I was curious to know the actual amount of carbonic acid
retained, a certain weight of the residue, obtained by evaporation iz vacuo, was
treated with cold water, and to the filtered solution was added a mixture of chlo-
ride of barium and caustic ammonia, which had been suffered to remain in con-
tact for some time; the precipitate produced would contain all the carbonic acid,
and when collected and washed with the proper precautions, it was ignited ; the
resulting percentage, calculated on the amount of residue employed, was almost
_ that of the bicarbonate to be described immediately.

The fiocky matter remaining undissolved by the water appears to be a new
base; it does not effervesce with acids, but dissolves tranquilly and completely,
and is again thrown down by ammonia in white flocks; with nitric acid, it yields
no crystalline salt, as ethylostrychnine does; it dissolves with the greatest ease
in spirits of wine, but is not to be obtained from this menstruum in a crystalline
state; the solution, which is, or soon becomes, of a fine pink colour, deposits no
crystals on standing for weeks even, but red transparent drops appear at the sides
and bottom of the vessel, and an amorphous residue remains on evaporating the
fluid to dryness; these characters evidently separate the product widely from
strychnine and ethylostrychnine, and must cause it to be considered a peculiar
base. It would be an interesting decomposition to follow out, but I had far too
little substance at my command to do more than observe the above facts at the
time, and the consumption of material necessary for its investigation is an obstacle
to the research.

Bicarbonate of Ethylostrychnine.—The preceding experiment having shewn the
tendency of the base to accumulate carbonic acid, I proceeded to seek a higher car-
bonate, by passing a stream of the washed acid gas into the solution, obtained by
the double decompositionjust mentioned. During this process, a very slight turbi-
dity ensued, and after the gas had passed through the fluid a considerable time,
this was filtered and obtained perfectly colourless; it proved to admit of evapo-
ration to dryness, 7 vacuo or at 212°, with similar results as to the properties
and composition of the residue. In the former case, a white crystalline mass.

ON SOME VEGETABLE ALKALOIDS. 39

—having, however, here and there, faintly claret-coloured spots—remains, which,
by continued drying, becomes a white enamel-like substance; the latter process
yields a crystalline residue of a reddish-yellow colour ; these products are the bi-
carbonate. The salt undergoes in a very slight degree the decomposition before
spoken of, but this is scarcely perceptible when evaporation is quickly performed ;
the flocky base produced, at 212° especially, being exceedingly minute in quantity.

The aqueous solution of the bicarbonate. and, though not deliquescent, the salt
is extremely soluble in water, has a powerful alkaline reaction, and proves a ready
means of forming the compounds too soluble to be got by double decomposition.
The dry salt dissolves completely in a little absolute alcohol ; the addition of good
ether to this fiuid causes in a little time the deposition of bicarbonate in very fine
colourless prismatic crystals, of great refractive power. In the analyses which
follow, the carbonic acid was estimated as before mentioned, and the specimens
were of different preparation :—

f sen grains, dried in vacuo, gave

2°150 ... carbonate of baryta.
4:990 ... dried at 212° Fahr., gave
™ | 9:380 ... carbonate of baryta.
Experiment. Calculation.
SSS
I. I,
Carbon, Ria tole qiet 65:09 Ci, 276
Ebydroreny: 4/0)! 6°60 3 28
Nitrogen,, . =. . 6:60 Ni 28
Oxyoen sO ch Fy us 11:34 OF 48
Carbonic Acid, . . 10:62 10°44 10°37 2(CO,) 44
100-00 424

These numbers agree perfectly with those required theoretically by a salt of the
base analogous to bicarbonate of potass, as expressed in the formula—

C,, H,, N, 0, HO CO,, HO CO,=C,, H,, N, 0, CO,, HCO,.

This salt is somewhat interesting, inasmuch as it is, I think, the first combina-
tion of one of the artificial ammonium bases with carbonic acid which has proved
definite by analysis. While on the subject, it will not be out of place to mention
some experiments made with the natural alkaloids, for the purpose of preparing,
if possible, similar salts with these bodies, as it gives the opportunity of correct-
ing an error to be found in the manuals. Thus, it is stated in LrepiG’s Traité,*
that a carbonate of strychnine is obtained both by precipitation of its salts with car-
bonated alkalies and solution of the base itself in water, through which a stream

* Lizsic. Traité de Chimie Organique, par Gerhardt ii., p. 630.
VOL. XXI. PART I. L

40 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

of carbonic acid gas is passed, it being deposited in this casein beautiful crystals.
I have carefully gone over those experiments, and satisfied myself that the sub-
stance in both cases is the pure base. A carbonate is certainly obtained by double
decomposition, between hydrochlorate of strychnine and carbonate of silver, but it
exists only for a short time, even in solution, as the gas escapes on standing, and
the pure alkaloid is deposited in fine, though small, crystals.

I could obtain no dry carbonates of morphia, codeine, papaverine, or narcotine ;
they behave like strychnine under the same circumstances. While these experi-
ments were in progress, my attention was called to the production of a definite
carbonate of quinine by LanGuois,* and I gave up the idea I had entertained of ex-
tending the observations to the vegetable alkaloids generally, as it is possible the
subject will be gone into at greater length by this chemist.

Hydrate of Ethylostrychnine.—I have mentioned already that potass and ammo-
nia fail to separate this base from its iodine combination, which is thrown down
unaltered from its aqueous solution by strong potass, and is also less soluble in
ammoniacal than in pure water. Oxide of silver readily effects the elimination of
the iodine ; in fact, when the solid salt is covered by moist oxide of silver, a few
minutes’ contact, in the cold, suffices to complete the change, iodide of silver re-
maining undissolved, and a fluid of a red purple colour being formed, which
contains all the base. When this is suffered to evaporate to dryness sponta-
neously, a crystalline purplish mass results, which contains some carbonic acid,
and dissolves in a small quantity of cold water; leaving, however, constantly, a
minute residue of the nature before spoken of in describing the monocarbonate.
Evaporation 7m vacuo over sulphuric acid produces a less crystalline residue, of a
similar colour, which is found to be completely soluble in hot absolute alcohol to
a purple fluid; a concentrated solution of this kind deposited, on cooling, a sub-
stance in colourless, small, prismatic crystals. These were collected on a filter,
washed from the coloured mother liquor with a little absolute alcohol and ether,
and finally dried out of contact of air. Tests, to be mentioned presently, having
shewn the deposit to be, as nearly as it is possible to be procured, the pure base,

it was retained 7m vacuo till it ceased to lose weight, and then gave these results
on analysis :—

4:643 grains, dried in vacuo, gave
11:600 ... carbonic acid, and
3°425 ... water.
Experiment. Calculation.
—————
Carbon... «| «1 68:18 67°81 Cie 276
Hydrogen, . . 8:19 7°61 E 31
Nitrogen, . . 6:87 ING 28
Oxygen,) 2). irger (ak 0, 72
100-00 407

* Chemical Gazette, 1853, p. 470.

ON SOME VEGETABLE ALKALOIDS. 4]

I must mention that the complete desiccation of this substance was extremely
tedious, occupying above a fortnight, and that in the state in which it was burned,
it wasa very light and bulky powder, highly electrical and hygroscopic, so that the
high percentage of hydrogen is not remarkable. The numerical results of the
above analysis admit of translation into the formula, which, in analogy with the
corresponding combination of potassa, the assumed congener of ethylostrychnine,
may be thus written :—

C,, Hp, N, 0, 0, HO + 3 aq,;

and this hydrate of oxide of ethylostrychnine differs from the known crystallized
hydrate of potassa, in containing an atom of water less.

The substance as analysed was not deliquescent; it dissolved immediately on
being covered with cold water, furnishing a red fluid, and leaving only a minute
flocky residue, which seemed to increase on application of heat; the solution,
made in the cold, became filled, almost immediately on the addition of a little
nitric acid, with the crystalline salt before spoken of as characteristic of the base,
and no effervescence was perceptible.

When the hydrate, carefully dried 27 vacuo, is dissolved in a quantity of ab-
solute alcohol, sufficient to prevent a deposit on cooling, the addition of some —
ether causes the formation of a tremulous jelly, which renders the whole fluid
semi-solid. On stirring for some time with a glass rod, this jelly gradually changes
into a crystalline substance ; by management of the respective amounts of alco-
hol and ether, very beautiful small crystals, perfectly colourless, may be obtained
at once, or on standing. To effect this result the hydrate must be well dried, or
it falls in purple, oily drops.

The hydrate cannot be freed of its water of crystallization by exposure to 212°,
as at this temperature it undergoes decomposition in a much greater degree; a
portion so heated was found to effervesce in a lively manner with acids, and
though it yielded plenty of the crystalline nitrate, yet when treated with cold
water it left a considerable residue of the character already described. I made
an analysis of a part of the substance giving these reactions with a view of ascer-
taining how far decomposition had proceeded, and give it with the understanding
of its approximative value :—

4-925 grains, dried at 212°, gave
12°600 ... carbonic acid, and
3°480 ... water.
Found. Calculation.
———
Carbon,. . . 69°77 69°34 Ce 276
Hydrogen,. . 7:85 7:53 ae 30
Nitrogen, . . 7:05 N, 28
Oxygen, “|. 16:08 O, 64

100-00 398

42 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

These numbers agree closely with those corresponding to a formula containing an
atom of water less than the preceding,

C,, Hy, N, 0, 0, HO + 2 aq.;

and it is just possible that the errors occasioned by the presence of carbonic acid
and the basic product of decomposition, both of which, after all, bear but a small
proportion to the whole substance, may counterbalance each other; I leave
the fact of the analysis, since it is some sort of control over that immediately
preceding.

A freshly prepared solution of the base, by action of oxide of silver on the
iodide, has a red purple colour and an extremely bitter taste; its reaction is highly
alkaline. It yields no immediate precipitate with solutions of barium and cal-
cium chlorides, but causes partial precipitation on application of heat; it throws
down from sulphate of magnesia, in the cold, a flocky precipitate, and also gives
with solutions of the heavy metallic oxides, and with alumina, immediate deposits ;
but I had not material sufficient to determine its solvent power in particular
cases. On being boiled, it evolves the odour of a volatile base. With chlorine,
bromine, and iodine, it yields products. When it, or its carbonate, is treated with
hydrosulphuric acid, and suffered to stand, a hyposulphite is found to result,
which may be obtained crystalline by evaporation, and is soluble in alcohol. This
base gives the same reaction as strychnine with sulphuric acid and chromate of
potass.

When iodide of ethylostrychnine is heated in a retort with excess of soda-lime,
a heavy oil distills over which is partly basic and partly insoluble in acids: the
hydrochloric solution of the soluble portion gave with bichloride of platinum an
uncrystalline salt, but I had not sufficient to determine if, in this decomposition, the
ethyl molecule attaches itself to the volatile base, which is no doubt either leu-
coline or ethyloleucoline.

Action of Iodide of Ethyl on Ethylostrychnine.—This reaction appears to result
in the formation of iodide of ethylostrychnine and some other product. I em-
ployed for the experiment the mother liquor of the hydrate which was analysed ;
this alcoholic fluid was sealed up in a tube with iodide of ethyl, and the whole
was heated for half-an-hour in boiling water. The liquid remained clear while
hot, but soon became turbid on cooling, and finally deposited some rounded trans-
parent yellowish grains. These proved, when separated from the mother liquor
by decantation, to be completely soluble in hot water; their solution deposited a
little flocky matter, and when filtered from this and evaporated, groups of stellate
crystals. These crystals agreed in characters with iodide of ethylostrychnine, and
furnished with oxide of silver a caustic yellow liquor, which became filled with
prismatic crystals on the addition of a little nitric acid. The alkaline solution

ON SOME VEGETABLE ALKALOIDS. 43

had not, it is true, therich red-purple afforded in former instances, but in all other
characters was quite the same.

The mother liquor of the grains, when distilled to a syrup, and, after the addi-
tion of some water, finally evaporated to dryness, left a red and green resinous
residue, which dissolved incompletely in hot water; the aqueous solution again
left a resin, only partially soluble, on evaporation ; there exists in this solution a
base—partially, at least—precipitable by ammonia, as an iodine compound. It is
possible this secondary product may somewhat affect the characters of the iodide
of ethylostrychnine, which, I think, is certainly formed, as might have been ex-
pected.

Action of Chloride of Amyl upon Strychnine.

Chloride of Amylostrychnine.—Strychnine, placed in contact with chloride of
amyl, is found to undergo, very slowly, a change quite analogous to that with
iodide of ethyl under the same circumstances. About eighty grains of the finely
powdered alkaloid being sealed up in a strong tube with two fiuid drachms of
chloride of amyl, and some ten of absolute alcohol, the vessel was placed in boil-
ing water, and retained at the same temperature for a long time. Complete solu-
tion took place in about fifty hours, and the heat was continued nearly forty-
eight hours longer. The rather oily liquid deposited nothing on cooling, and left,
on distillation to a syrup, a thick mass which finally dried up to a crystalline re-
sidue. This proved to be the chlorine salt of a base generally analogous to the
ethyl product; it was very soluble in hot water, and crystallizable from a very
strong boiling solution on cooling, or a more dilute one by evaporation, in fine
colourless prisms.

I must mention that, in the first place, the whole of the product was dissolved
in hot water, and the fluid evaporated to crystallization; the resulting crystals
have their composition represented in analysis I. below, and must have contained
any strychnine salt, or a great part of it, had any been originally present, as this
is less soluble than the new one.

The entire mother liquor of these crystals was super-saturated by ammonia,
no precipitate appeared for some time; on stirring, however, a certain quantity of
a crystalline deposit fell, which presented the characters of strychnine. The
ammoniacal fluid was suffered to stand two hours or so, and then filtered and eva-
porated to dryness at 212°. The residue was found to be completely soluble in
hot water, or left but a little insoluble strychnine, and was made to crystallize like
the first product. These are the crystals employed in analysis II., and could con-
tain no strychnine.

The identity of the analytical results furnished by these two salts, and the ap-
pearance of the strychnine, caused me to make direct experiments with ammonia,
to be described presently; in the meantime, the analyses of the salts, obtained as

VOL, XXI. PART I. M

44 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

above, are given ; the chlorine was determined in a specimen different from either
of the others :—

4-505 grains, dried at 212°, gave
11°425 carbonic acid, and
3165 ++ water.
4-213 +. dried at 212°, gave
10-750 ... carbonic acid, and
2-990... - water,
4140 .., dried at 212°, gave
MI) 1:345 ++ chloride of silver.
Found. Calculation.
eS SS
He Il. Til. Mean.
Carbon," ja, ;.: 69°16 f6;58 69°37 69-41. C,, 312
Hydrogen, . . 780. 78 7°84 756 H,, 34
Nitrogen. '” ca. 6:22 N, 28
Oxyeen;, Aliant 8-92 O, 40
@hilormne, yy . a 8:03 8:03 7:89 Cl 35:5
100-00 449°5

These numbers indicate a change quite analogous to that before seen to obtain
with iodide of ethyl, and it may be expressed thus :—

C,,H,,N;0,; + 6), Hj, Ob '=''Cy By NPOKie Hy pala rc., Bin og
ees ME aT eA =
Strychnine. New Salt.

but the salt, as deposited from water, retains an equivalent of the same at 212°,
and is, according to the above analysis—

C,, H,, N, 0, Cl + HO;

while, in the air-dry state, the crystals contain in addition seven atoms, which
they readily part with, as these numbers shew :—

8:170 grains, air-dry, lost at 212°

1:025 --- water;

which give a percentage of 12°54; and 12°29 is that required by a loss of seven
atoms of water in a salt of the formula,—

Cyp Has Np 0, Cl, HO + 7,aq.

The hydrated chloride of amylostrychnine crystallizes from water in fine, thick,
colourless, oblique rhombic prisms, which have a peculiar greasy appearance when
dry; it is very soluble in alcohol. Its aqueous solution is not affected by dilute
potass, or by ammonia, except when left long in contact ; but is immediately pre-
cipitated by strong potass, the salt being thrown down unchanged. Oxide of silver
eliminates the chlorine, leaving the base dissclved. When heated, the dry salt

ON SOME VEGETABLE ALKALOIDS. 45

fuses and gives off, first water, then acid vapours, and finally, with intumescence
and blackening, alkaline fumes of & very nauseous odour, which also affect the
throat most unpleasantly.

Its aqueous solution gives, with that of mercuric chloride, a heavy white pre-
cipitate, which is difficultly soluble in boiling water, and is deposited in the cold
in very small and separate crystals ; these seem, when magnified, to be prisms and
octahedra ; it furnishes, with chloride of gold, an insoluble amorphous yellow pre-
cipitate. With bichloride of platinum a pale yellow uncrystalline precipitate is
obtained, but this could not, in three trials, be obtained of constant composition ;
the platinum came always much too high, even above that of the strychnine salt
itself, in two cases, by 0°3 to 0°7 per cent.

Bichromate of Amylostrychnine.—This salt was obtained from the mother liquor
of salt II. above, by addition of bichromate of potass ; it fell as a crystalline yellow
salt, soluble in boiling water; when ignited, it gave the following result :—

6°418 grains, dried at 212°, gave
0:965 +. sesquioxide of chromium.

The percentage of anhydrous chromic acid corresponding to this number is 19°63; _
and 19°37 is that required by a salt, analogous to that of the ethyl base, of the
formula—

Cz. H,3 N, 0, CrO,, H CrO,.

There exists also a crystalline chromate.

Nitrate of Amylostrychnine.—This was prepared from the crystals of the chlo-
ride I., by double decomposition with nitrate of silver in warm liquids. It ismore
soluble than the corresponding salt of ethylostrychnine; but it is by no means of
great solubility in cold water, though readily taken up in the heat. It crystallizes
from hot water in very beautiful radiated groups of colourless needles; the ana-
lysis of these gave the numbers which follow :—

3°695 grains, dried at 212°, gave
8-850 ... carbonic acid, and
2:415 ... water.
Found. Calculation.
See
Carbony..':). © 7yagyso:a2 65-54 oe a2
Hydrogen, . . 7:26 7:14 Jeb 34
Nitrogen, . .- 8°82 N, 42
Oxygen 96's) 18°50 0,, 88
100:00 476

and it appears that this salt is also not anhydrous at 212°, its formula being—

C,. H,, N, 0, NO, + HO.

46 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL

The air-dried crystals contain, in addition, ten atoms of water :—

4-390 grains air-dry salt, lost at 212°
0685 +. water.

This number leads to a percentage of 15°60; and 15:90 is that corresponding to a
loss of ten aq. by a salt of the composition—

C.. H,, N, 0, NO,, HO + 10 aq.

The aqueous solution of the nitrate gives, with that of mercurous nitrate, a
crystalline deposit in the form of colourless needles ; these are no doubt a double
salt.

Hydrate of Amylostrychnine.—The chloride furnishes, with oxide of silver in
water, a rich red purple fluid of a highly alkaline nature, which agrees most strik-
ingly in its characters with the solution of ethylostrychnine ; indeed, the two
might be readily mistaken for each other; their deportment with metallic salts,
and on evaporation, in vacuo or at 212°, is precisely the same. The flocky basic
product by evaporation in the case of each, bears possibly the same relation to its
congener which the parent bases mutually possess.

The residue left 2 vacuo dissolves to a very rich purple fluid in hot absolute
alcohol, and ether causes in this solution an abundant and quickly appearing de-
position of radiated white needles. I have not as yet analysed these, but I appre-
hend they must bear a close analogy to the hydrate of ethylostrychnine.

The chloride of amylostrychnine seeming to have a tendency to decompose in
contact with ammonia, some solutions of the salt were supersaturated with this
alkali; in no instance did any immediate precipitate occur; but in all, after the
lapse of a shorter or longer period, crystalline deposits were formed, while the
fluids assumed a reddish-brown colour ; in some cases the product was but micro-
scopic at the end of a fortnight, while other specimens furnished within this time

quite a decided crystallization on the sides of the vessels. These crystals had the
qualitative characters of strychnine; and it is easy to imagine a decomposition
taking place in which this alkaloid should be regenerated with the formation of
amylamine; thus—

Cro Hyg N, 0, Cl4 NH, =C,, H,, N, 0,+C,, H,, N, HCl.

I have not as yet been able to verify this equation; for there has remained much
of the amylostrychnine undecomposed in those cases where I tried to prove the
existence of amylamine.

In the hope of hastening the decomposition, some of the mother liquor of the
chloride was sealed in a tube with strong ammonia; the vessel was kept in
boiling water for many days; a rather dark-coloured deposit gradually formed,
while the liquid itself became brown and rather mucilaginous. At the end of a

ON SOME VEGETABLE ALKALOIDS. 47

week the tube was opened, but I could gain nothing decisive as to the evident de-
composition which had taken place, and which seems of a more complex nature
than had been anticipated.

The brown deposit was for the most part soluble in hydrochloric acid, but
did not present the characters of pure strychnine when reprecipitated by ammonia.
Its mother liquor, from the tube, was evaporated to dryness at 212° to expel the
excess of ammonia, and it left a residue which had a most remarkable resemblance
to common glue in appearance and odour: this contained the chlorine salt of some
base, and when dissolved in water, and decomposed by nitrate of silver in ex-
cess, the fluid, filtered from the chloride of silver, gave in a few minutes a brilliant
metallic mirror, but no crystalline salt.

These decompositions, at both temperatures, seem worthy of study. I may

mention that chloride of ethylostrychnine, in contact with aqueous ammonia in
the cold, also yields, after the lapse of some days, a small deposit of most minute
crystals.
_ [have not at present experimented further with these substances, but hope to
be able to render their history more complete, and, if possible, to clear up some
points touched upon in this paper, by studying their especial products of decomposi-_.
tion in these cases. I have the intention also of submitting some of the other alka-
loids, yet unexamined, to a similar investigation.

With regard to what has been actually brought forward in the present commu-
nication, I would draw the following inferences ;—

That the new basic products, ethylo and amylo-strychnine are analogous to the
compound ammonium bases of Hofmann, and quite distinct from the natural
fixed alkaloids. In their resemblance to metallic oxides, and the combinations
they form with water and acids, they shew, in common with these, general family
features, while special distinctions exist as individual characteristics, and are to
be paralleled in many saline compounds.

That the already complex molecule in the vegetable alkaloids is rendered more
susceptible of change by association with additional hydrocarbons.

That as regards the constitution of strychnine, this alkaloid appears to be
made up of a complicated molecule, in which the one atom of nitrogen, as in am-
monia, etc., is associated with a nitrogenous aggregate of elements, whose function
is that of three atoms of hydrogen, and whose nitrogen is in a distinct form of com-
bination, as yet undetermined, from that of the first, generic atom. The expres-
sion of such a composition may be attempted thus :—

H

C, Hy» ‘N, 0, =! C,H, N 0,= 1e} +N

—_—_—_— H
Strychnine.

VOL. I. PART I. N

48 ACTION OF HALOGEN COMPOUNDS OF ETHYL AND AMYL, &C.

And the association of this molecule with any alcohol hydrocarbon occasions the
production of an ammonium congener, which, as it exists i combination with
some electronegative element, may be written thus :—

H
Ga Ha +1)

Ga Hy NO, =| oe

In conclusion, I give a tabular view of the new compounds mentioned in the
preceding pages ; and, in doing so, I have adopted the termination ‘‘ ium” for the
bases, in analogy with the name ammonium; strychnia, the old name of the alka-
loid in English, being, it seems to me, the more appropriate designation for
the analogue of ammonia; and it would be but consistent with the ammonium
theory, to look upon the alkaloid in entering into combination, with hydrochloric
acid for instance, as undergoing the same process as the volatile type, and to speak
of the new salt as chloride of strychnium. The products of this investigation, then,
are the following :—

Hydriodate of Papaverine, C,, BH, SOA HE
Iodide of Ethylostrychnium, : Ca Ha, Op.
Hydrated oxide of do., . ; . erystallized C,, H,, N, 0, O, HO,+3 aq.
Nitrate of do., : . ss Ug Hay NS OSU,
Bichromate, : ; q . dried at 212° C,, H,, N, O, CrO,, HCrO,.
¥s : crystallized C,, H,, N, 0, CrO,, HCrO, +2 aq.

Bicarbonate, = : : Cie He, Ny 0, GOL Bowe
Platinum compound, . . . erystallized C,, He, N, 0, Oly Pte
Chloride of Amylostrychnium, . dried at 212° OC, H,, N, O, Cl, HO.

iH by if : . erystallized C., H,, N, 0, Cl, HO+7 aq
Nitrate of Oxide, ‘ F . dried at 212° C,, H,, N, O, NO,, HO.

a : : : . erystallized C., H,, N, 0, NO,, HO +10 aq.
Bichromate, , d 5 . dried at 212° ~C,, B,, N, 0, Cr0,, HCrO,

( 49 )

V.— On a General Method of Substituting Iodine for Hydrogen in Organic
Compounds, and on the Properties of Iodopyromeconic Acid. By Mr James F.
Brown,* Assistant to Professor ANDERSON, Glasgow.

(Read 3d April 1854.)

In a paper on pyromeconic acid read before this Society, and since published
in the Philosophical Magazine for September 1852, I have detailed the prepara-
tion and properties of a compound obtained by the substitution of an equivalent
of bromine for an equivalent of hydrogen in that acid. Having observed that
this substitution was very easily effected, I was induced to attempt the forma-
tion of an iodopyromeconic acid, in the hope of adding one to the very few in-
stances in which the direct substitution of iodine for hydrogen has been found
possible. For this purpose, I digested pyromeconic acid with tincture of iodine,
but no success attended the experiment, the acid remaining entirely unchanged.
The failure of this attempt led me to speculate as to its cause, and to contrive a —
method of producing the required substitution which has proved entirely suc-
cessful, and has the further advantage of being perfectly general, so that its ap-
plication will enable chemists to obtain iodine substitution compounds in cases
in which they have hitherto failed.

A few preliminary observations on the cause of substitution will render in-
telligible the nature of the method in question. Selecting the production of
bromopyromeconic acid and of trichloracetic acid, as characteristic examples of
substitution, we have the following formule representing the changes which

occur :—
C;, H,0, + Br, = C,, H, Br O,'+ H Br
es ———————————S_LE
Pyromeconic Acid. Bromopyromeconic Acid.
C,H, 0,+ C,= 06, HCL 0,4 3HC
——" === —_—_—_—_——
Acetic Acid. Trichloracetic Acid.

In these, as in every other case of substitution, the chlorine and bromine ob-
viously perform a twofold function, one portion entering into the complex atom
in the place of an equivalent quantity of hydrogen, which is eliminated in com-
bination with another quantity eithér of chlorine or bromine ; and the new pro-
duct contains the same number of atoms, and is commonly said to belong to the
same type. In talking of such substitution, it is not unfrequently said, that the

* It is with deep regret I have to record here the early death of Mr Jamzs Brown, who, in this
and a previous communication read before this Society, had given such high promise of future eminence.
He died at Glasgow on the 2d July, after an illness of only twelve hours’ duration—T. A.

VOL. XXI. PART I. O

50 ON A GENERAL METHOD OF SUBSTITUTING

atom of chlorine simply displaces or pushes out the atom of hydrogen, and so
comes to occupy its place, but a very slight consideration enables us to see that
it is really dependent, not so much on the quantity of chlorine which remains in
the compound as on that which escapes in combination with hydrogen. The
original substance in all cases of substitution, forms a perfect molecular group in
which the individual affinities of the different elementary atoms are properly
balanced, and the whole remains in a quiescent state. But when another ele-
ment, such as chlorine, comes in contact with this complex group of atoms, it im-
mediately exerts its affinity for the hydrogen, with which it easily combines, and
withdraws the whole or part of it from the compound. In this way a gap is
produced in what was before a perfect group, the balance of the affinities of its
elements is destroyed, and there must either be a complete readjustment of its
molecular arrangements, or some other element must stop the gap and produce
another perfect molecule not differing from the original substance in the arrange-
ment of its parts, but only in the presence of one or more atoms of a different
sort from those which it previously contained. Considered in this point of view,
it becomes at once obvious that we fail to produce the substitution of iodine for
hydrogen, not from any inability of the former to occupy the place of the latter,
but simply because it has not a sufficiently powerful affinity for hydrogen to
withdraw it from the compound, so as to leave an empty space into which an-
other portion may enter. It occurred to me that as chlorine and bromine in
causing a substitution exercise the two different functions already alluded to, one
quantity withdrawing hydrogen, and the other simply slipping into the vacant
space, it might be possible to produce an iodine substitution by associating that
element with some substance having a sufficiently powerful affinity for hydrogen,
to open the door as it were, and leave nothing for it to do but to step into the
place prepared for it.

For this purpose I selected the bromide of iodine, as being most likely to fulfil
the required conditions. It was prepared by agitating bromine water with a
considerable excess of iodine, and decanting the reddish-brown solution from the
undissolved residue. When this bromide was added to pyromeconic acid, a
change rapidly occurred, the solution became colourless, and iodopyromeconic
acid was produced. Having succeeded in this way, I then tried the chloride of
iodine, and having found it to act equally well, I made use of it in all my subse-
quent experiments. The chloride of iodine was prepared by passing a rapid cur-
rent of chlorine through finely-pounded iodine suspended in a small quantity of
water, and kept in continual agitation, care being taken to stop the process before
the iodine was entirely dissolved. A moderate heat is produced during the combi-
nation, and the fluid should be kept as cool as possible.

In order, therefore, to obtain iodopyromeconic acid, a freshly-prepared solu-
tion of the chloride of iodine is mixed with a cold saturated solution of pyrome-

IODINE FOR HYDROGEN IN ORGANIC COMPOUNDS, &c. ol

conic acid. The solution is instantly decolorized, and the new acid is deposited
in the form of fine delicate plates, which are so abundant as to render the fluid
almost semisolid. The only precautions necessary are to avoid the use of a hot
solution of the acid, and an excess of the chloride, as the product, under such
circumstances, becomes coloured, owing to the occurrence of a further decompo-
sition, to be afterwards referred to. The change which first takes place is re-
presented by the equation :—

CoH OL ih C.H. 10, i HCl,

The crystals of iodopyromeconic thus precipitated are in a short time filtered off
and washed with cold water; they are then finally dissolved in boiling alcohol,
from which they again deposit themselves, upon cooling, in perfectly colourless
plates, having a high degree of lustre. The acid is sparingly soluble in cold
water; but at a boiling heat it dissolves more readily, and crystallizes again from
the solution in long, slender needles, possessing a slightly acid reaction. Acids and
alkalies increase its solubility in water, but it is easily decomposed, if boiled with
strong caustic potash. It is also decomposed by concentrated nitric acid, with
the separation of free iodine. It gives a yellowish-white precipitate with nitrate
of silver, soluble in ammonia, and with perchloride of iron it produces a deep
purple colour, but no precipitate. It suffers no loss of weight at 212°, but heated
to a higher temperature, it first fuses to a black fluid, and is then suddenly decom-
posed, with the evolution of a large quantity of iodine.

The combustion of iodopyromeconic acid was attended with some difficulty,
for it was found that not only the acid itself, but even its lead salt permitted
the iodine to escape in the free state, when burned either with chromate of lead,
or with a mixture of oxide of copper and litharge. This would have been of
little moment in determining the constitution of a substance such as iodopyro-
meconic acid, where the mode of its formation sufficiently indicates its com-
position, and the determination of the carbon and iodine would have been quite
sufficient to fix its formula ; but having observed the same peculiarity in another
substance afterwards to be described, in which the exact determination of the
hydrogen was essential to the establishment of its formula, I was compelled to
devise some method by which the iodine might be retained, and the following is
that which I found most successful.

The substance to be analysed was mixed with chromate of lead, and a small
quantity of fused litharge reduced to a fine powder; the mixture was then intro-
duced into a long combustion tube, held with its point downwards, and at the same
time there were dropped into it small pieces of metallic lead, which remained at
the under-side of the tube, and so arranged as to be about three inches apart.
After the whole of the mixture had been introduced, and the remaining space
in the interior of the tube filled up with chromate of lead, the point was turned

52 ON A GENERAL METHOD OF SUBSTITUTING

upwards, and by slight tapping a passage opened throughout the w. and so
of the tube, while the pieces of lead projecting above the surface meltew that
application of heat, and by exposing a metallic surface during the time combustion
was going on, served to retain all the iodine.

The results of analysis are as follows: The hydrogen of No. 1 was not weighed,
as, from its combustion being effected in the ordinary way without lead, the small
end of the chloride of calcium tube was completely covered with small plates of
iodine.

No. 1. 4°893 grains substance burned with chromate of lead, gave

4620 ... carbonic acid.
No. 2. 7:298 grains substance burned with chromate of lead, litharge, and metallic lead, gave
6759 +.» carbonic acid, and
"975 J... ‘water.
No. 3. 6:85 grains substance heated with carbonate of potash, gave
6°707 ... iodide of silver.
No. 1. No. 2. Calculation.
SSS eS
Carbon; |.-..-.- .2b°7650 25:25 25:19 G.. 60
Hydrogen, eee 1:48 1:26 z
Oxygeny) 5 21; oes os 207" GO. 48
Todine;...°\\5° ys, 46 . 2 B00 oo 53°38 I 127°1
100-000 100-00 100-00 238°1

These results correspond exactly with the formula, C,, H, 10,+HO.

Iodopyromeconic acid is monobasic, and forms salts, of which I have minutely
examined only those of baryta and lead. It does not appear to form an ammonia
salt.

Iodopyromeconate of baryta is readily prepared by mixing together alcoholic
solutions of acetate of baryta, and of the acid made slightly alkaline with am-
monia. After a short time it deposits a fine network of delicate crystals, of
little solubility either in cold or hot water or alcohol. It is alkaline to litmus
paper, and at 212° it suffers no loss of weight.

The following result was obtained on igniting the salt with sulphuric acid :—

4°49 grains substance gave

1:63 --- sulphate of baryta.
which corresponds to the formula, BaO C,, H, 10,+HO, as shown by the follow-
ing calculation :—

Experiment. Calculation.
a —_——_—=$———
Carboniir i te ay 19-068 Co 60
Hydrogen, . . ae a ees 3
Oxygen: Sa he oe 15:255 0; 48
Todiries 1). Rae ee 40°394 I 127-10
Baryta,, (: <5: <23'64 24-329 Ba O 76:55

100-00 100-000 314°65

IODINE FOR HYDROGEN IN ORGANIC COMPOUNDS, &c. 53

de dei | comeconate of lead is readily obtained as a fine colourless amorphous

in the.foy"? OF mixing alcoholic solutions of the acid and acetate of lead, with the
‘addition of a small quantity of ammonia. As thus prepared, it is apt to carry
down an excess of oxide of lead, which is easily removed by warm acetic acid.
It is of sparing solubility in alcohol or water, and becomes highly electrical when
rubbed. This salt, contrary to expectation, evolves free iodine, like the acid
itself, when burned with chromate of lead; but the phenomenon is probably
owing to the decomposition of the salt taking place at a temperature much
lower than that sufficient to enable the iodine to combine with lead. For this
reason I contented myself with a determination of its oxide of lead, which was
effected by igniting the salt, after the addition of a few drops of concentrated
sulphuric acid :—

6:15 grains substance, dried in the air, gave
2°76 ++ sulphate of lead.

corresponding to the formula, PbO, C,, H, 10,, as shown by the subjoined cal-
culation :—

Experiment. Calculation.
aa

Carbonam sere es 17°612 Cio 60
Hydrogen,. . . sie 587 Hi, 2
Oxygen, ...). hag 11:743 O, 40
Iodine, . : Jae 37°309 I 127-1
Oxide of lead, . 88:03 32°749 PbO 111-56

100-00 100-000 340°66

I have already mentioned, that when the quantity of chloride of iodine em-
ployed is larger than is requisite for the production of iodopyromeconic acid, the
fluid acquires a yellow colour, due to the presence of another compound, of very
remarkable characters, produced by a further decomposition of pyromeconic acid,
and to which I gave the name of iodomecone. When potash is gradually added
to the fluid, after separation of the iodopyromeconic acid, a blackish precipitate
immediately falls, which rapidly dissolves on agitation of the fluid, while a peculiar
odour is evolved. After the addition of the potash has been continued for some
time, a point is reached at which the precipitate assumes a lighter colour, is no
longer dissolved, and is not increased by further addition of the alkali. The
precipitate is then filtered from the alkaline fluid, washed with cold water, and
purified by repeated crystallization from boiling alcohol. By subsequent experi-
ments, I ascertained that it was easy to convert pyromeconic acid entirely into
this compound, by adding a large quantity of chloride of iodine, when the crys-
tals of iodopyromeconic acid at first formed rapidly disappeared, and carbonic
acid was evolved. Exactly similar effects are produced by bromide of iodine.

Jodomecone is obtained in large hexagonal plates of a bright yellow colour

VOL. XXI. PART I. P

54 ON A GENERAL METHOD OF SUBSTITUTING

and brilliant lustre, and having an odour resembling that of saffron. It is inso-
luble in water, soluble in alcohol, especially on boiling, and in ether. It is inso-
luble in hydrochloric acid, and may be boiled with that reagent, without suffering
decomposition. Strong nitric acid attacks it with great violence, but does not
effect a complete oxidation of all the iodine. It is unacted on in the cold by strong
sulphuric acid, but if heated, it is decomposed with the liberation of iodine.
Caustic potash when long boiled with it, removes a very small quantity of iodine.
It does not affect litmus paper, and seems to possess neither acid nor basic pro-
perties. It sublimes unaltered at a temperature greatly below that of boiling
water.

These characters closely approximate to those of iodoform, and I at first con-
sidered it to be that substance. The analysis, however, made with every care,
and on specimens prepared at different times, gave results which cannot be made
to agree with the formula of that substance.

The analysis are as follows :—

No. 1. 7:141 grains substance, air-dry, gave
0:913 ++. carbonic acid, and
tee water.

No. 2. 4°365 grains substance, air-dry, gave
carbonic acid, and

0: 164 +++ water.
No. 3. 8:153 grains substance, air-dry, gave
0-958 ++.» carbonic acid, and
0:346 --- water.
No. 1. 5°697 grains substance, air-dry, gave
9-706 +--+ iodide of silver.
No. 2. 3°611 grains substance, air-dry, gave
6:140 .--- iodide of silver.
No. 1. No. 2. No. 3.
Carbon, /. ¢ on aoe lost. 3°204
Hitydropen:)('9. fs) ee 0-417 0°471
Oeyeens, ots ash tues sage 4:440
fodines) js). 5), eee 92-060 91°885
100-000 100-000 100-000
Mean. Calculation.
Ee
Carbon, =>... S307 3°258 C, 36
Hydrogen, . . 0:444 0364 Hy 4
Oxygen, . . . 4:247 4:344 0, 48
Lodine, (2. O72 92-034 T, 1016:8
100-000 100°000 1104:°8

The formula is therefore C, H, I, O,.

IODINE FOR HYDROGEN IN ORGANIC COMPOUNDS, &c. 9)

The decomposition by which iodomecone is produced from pyromeconic acid,
now becomes obvious. It is represented by the following equation :—

C,, H, 0, + 8101 + 8HO = C, H, I, 0, + 400, + 8 HCl

This being the mode of its formation, it seemed probable that meconic and
comenic acids, which differ from pyromeconic acid only by the elements of carbonic
acid, would yield the same substance, when acted on by chloride of iodine. Ac-
cordingly, I have found that it is immediately produced with all its characteristic
properties from these acids, by the same process. The relations of this substance
to meconic and pyromeconic acids, are of a very remarkable character, and can-
not at present be distinctly brought out. It obviously belongs to the same class
as the very curious product obtained by Canours, by the action of bromine ‘on
citric acid, and which he has called bromoxaform. According to this chemist,
when bromine is added to citrate of potash, effervescence takes place from the
evolution of carbonic acid, and on the addition of potash, an oily matter is thrown
down, which consists of three substances, one bromoform, the other a crystalline
solid bromoxaform, and the third apparently an accidental product, for it is ob-
tained in too small quantities to admit of examination. It can scarcely be doubted
that bromoxaform would be the only product, if the action could be properly
moderated, and that the bromoform is a secondary product of the former substance,
from which indeed it is readily obtained, by treatment with caustic potash. If
this be the case, the decomposition of citrate of potash would be quite analogous
to that of pyromeconic acid, as represented in the equation :—

C,, H, K, 0, + 2HO + Br,, = C, HBr, O, + 6CO, + 3K Br + 6H Br.

Citrate of Potash. Bromoxaform.

The relation which these curious substances bear to their parent acids is very
obscure, and cannot be elucidated without further experiments. In regard to
iodomecone, the small quantity in which I was able to obtain it, has prevented
my following out its decompositions as I could have wished, but I propose extend-
ing this investigation to some of the stronger acids by which means some light
may probably be thrown upon the constitution of these bodies.

It was my desire to have extended my examination of the iodine substitution
products obtained by chloride of iodine, to some other substances. As yet, how-
ever, I have only tried codeine; but the instability of the compound produced has
occasioned such difficulties, that I have hitherto been unable to arrive at satisfac-
tory results. When chloride of iodine is added to a concentrated solution of hy-
drochlorate of codeine, a fine yellow crystalline precipitate makes its appearance.
It is insoluble in water, but readily soluble in boiling alcohol. If this solution is
carefully effected, and too much of the substance be not added, it crystallizes on
cooling in stellar groups, of a fine red colour, but if a large quantity is dissolved,

D6 ON A METHOD OF SUBSTITUTING IODINE FOR HYDROGEN, &c.

it is deposited as a perfectly amorphous mass. Unfortunately, the iodine is re
tained with a very feeble affinity, and I have found that at every crystallization
a small quantity is separated and remains in the fluid, so that results of a satisfac.
tory character could not be obtained on its analysis. It is soluble in hydrochloric
acid, and if the solution be made hot, it deposits at first an oily substance.
which aftewards concretes to a flocky mass. Both ammonia and potash precipitate
it from its solution in hydrochloric acid, the former giving a slightly coloured
substance. With chloride of platinum it yields a bright yellow precipitate, one
determination of the platinum in which gave 12:20 per cent.; 11-95 corresponds
to the formula, C,, H,, I, NO, HCl Pt Cl, + HO., which represents the hydrated
salt of a base, which may be called di-iodocodeine, as being derived from codeine
by the substitution of two atoms of iodine for two of hydrogen.

These experiments were conducted in the laboratory of Professor ANDERSON,
to whom I am much indebted for assistance during their prosecution.

V1.—WNote on the Possible Density of the Luminiferous Medium and on the Mechani-
cal Value of a Cubic Mile of Sunlight. By Professor WitL1AM THomson.

(Read Ist May 1854.)

That there must be a medium forming a continuous material communication
throughout space to the remotest visible body is a fundamental assumption in
the undulatory Theory of Light. Whether or not this medium is (as appears to me
most probable) a continuation of our own atmosphere, its existence is a fact that
cannot be questioned, when the overwhelming evidence in favour of the undula-
tory theory is considered ; and the investigation of its properties in every possible
way becomes an object of the greatest interest. A first question would naturally
occur, What is the absolute density of the luminiferous ether in any part of space ?
I am not aware of any attempt having hitherto been made to answer this ques-
tion, and the present state of science does not in fact afford sufficient data. It
has, however, occurred to me that we may assign an inferior limit to the density
of the luminiferous medium in interplanetary space by considering the mechani-
cal value of sunlight as deduced in preceding communications to the Royal
Society from PoviLLeEr’s data on solar radiation, and JouLe’s mechanical equiva-
lent of the thermal unit. Thus the value of solar radiation per second per square
foot at the earth’s distance from the sun, estimated at -06 of a thermal unit
centigrade, or 83 foot-pounds, is the same as the mechanical value of sunlight in
the luminiferous medium through a space of as many cubic feet as the number
of linear feet of propagation of light per second. Hence the mechanical value of
the whole energy, actual and potential, of the disturbance kept up in the space

83 819
S 792000 x 5280, °' yor °

a foot-pound. The mechanical value of a cubic mile of sunlight is consequently
12050 foot-pounds, equivalent to the work of one-horse power for a third of a
minute. This result may give some idea of the actual amount of mechanical
energy of the luminiferous motions and forces within our own atmosphere.

of a cubic foot at the earth’s distance from the sun,* i r

* The mechanical value of sunlight in any space near the sun’s surface must be greater than in
an equal space at the earth’s distance, in the ratio of the square of the earth’s distance to the square
of the sun’s radius, that is, in the ratio of 46,400 to 1 nearly. The mechanical value of a cubic foot of
sunlight near the sun must, therefore, be about -0038 of a foot-pound, and that of a cubic mile
560,000,000 foot-pounds.

VOL XXI. PART I. Q

58 PROFESSOR W. THOMSON ON THE POSSIBLE DENSITY OF THE

Merely to commence the illumination of three cubic miles, requires an amount
of work equal to that of a horse-power for a minute; the same amount of
energy exists in that space as long as light continues to traverse it; and, if the
source of light be suddenly stopped, must be emitted from it before the illumi-
nation ceases.* The matter which possesses this energy is the luminiferous
medium. If, then, we knew the velocities of the vibratory motions, we might
ascertain the density of the luminiferous medium; or, conversely, if we knew
the density of the medium, we might determine the average velocity of the mov-
ing particles. Without any such definite knowledge, we may assign a superior
limit to the velocities, and deduce an inferior limit to the quantity of matter, by
considering the nature of the motions which constitute waves of light. For it
appears certain that the amplitudes of the vibrations constituting radiant heat
and light must be but small fractions of the wave lengths, and that the greatest
velocities of the vibrating particles must be very small in comparison with the
velocity of propagation of the waves. Let us consider, for instance, plane polar-
ized light, and let the greatest velocity of vibration be denoted by 7; the distance
to which a particle vibrates on each side of its position of equilibrium, by A ; and
the wave length, by A. Then if V denote the velocity of propagation of light
or radiant heat, we have
v A
Taian

and therefore if A be a small fraction of A, v must also be a small fraction
(2 + times as great) of V. The same relation holds for circularly polarized light,
since in the time during which a particle revolves once round in a circle of radius
A, the wave has been propagated over a space equal to A. Now the whole me-
chanical value of homogeneous plane polarized light in any infinitely small space
containing only particles sensibly in the same phase of vibration, which con-
sists entirely of potential energy at the instants when the particles are at rest at
the extremities of their excursions, partly of potential and partly of actual energy
when they are moving to or from their positions of equilibrium, and wholly of
actual energy when they are passing through these positions, is of constant
amount, and must therefore be at every instant equal to half the mass multiplied
by the square of the velocity the particles have in the last-mentioned case. But
the velocity of any particle passing through its position of equilibrium is the
greatest velocity of vibration, which has been denoted by 7; and, therefore, if 9
denote the quantity of vibrating matter contained in a certain space, a space of
unit volume for instance, the whole mechanical value of all the energy, both

* Similarly we find 15000 horse-power for a minute as the amount of work required to generate
the energy existing in a cubic mile of light near the sun.

LUMINIFEROUS MEDIUM, AND THE MECHANICAL VALUE OF SUNLIGHT. 59

actual and potential, of the disturbance within that space at any time is } 0 v°.
The mechanical energy of circularly polarized light at every instant is (as has been
pointed out to me by Professor Stokes) half actual energy of the revolving particles
and half potential energy of the distortion kept up in the luminiferous medium; and,
therefore, v being now taken to denote the constant velocity of motion of each par-
ticle, double the preceding expression gives the mechanical value of the whole dis-
turbance ina unit of volume in the present case. Hence it isclear, that forany ellipti-
cally polarized light the mechanical value of the disturbance in a unit of volume will
be between Sov? and 02’, if v still denote the greatest velocity of the vibrating par-
ticles. The mechanical value of the disturbance kept up by a number of coexisting
series of waves of different periods, polarized in the same plane, is the sum of the
mechanical values due to each homogeneous series separately, and the greatest
velocity that can possibly be acquired by any vibrating particle is the sum of the
separate velocities due to the different series. Exactly the same remark applies
to coexistent series of circularly polarized waves of different periods. Hence the
mechanical value is certainly less than ha/f the mass multiplied into the square of
the greatest velocity acquired by a particle, when the disturbance consists in the
superposition of different series of plane polarized waves ; and we may conclude,
for every kind of radiation of light or heat except a series of homogeneous circu-
larly polarized waves, that the mechanical value of the disturbance kept up in any
space is less than the product of the mass into the square of the greatest velocity ac-
quired by a vibrating particle in the varying phases of its motion. How much less
in such a complex radiation as that of sunlight and heat we cannot tell, because
we do not know how much the velocity of a particle may mount up, perhaps even
to a considerable value in comparison with the velocity of propagation, at some
instant by the superposition of different motions chancing to agree; but we may
be sure that the product of the mass into the square of an ordinary maximum
velocity, or of the mean of a great many successive maximum velocities of a
vibrating particle, cannot exceed in any great ratio the true mechanical value of
the disturbance. Recurring, however, to the definite expression for the mechani-
cal value of the disturbance in the case of homogeneous circularly polarized light,
the only case in which the velocities of all particles are constant and the same, we
may define the mean velocity of vibration in any case as such a velocity that the
product of its square into the mass of the vibrating particles is equal to the whole
mechanical value, in actual and potential energy, of the disturbance in a certain
space traversed by it; and from all we know of the mechanical theory of undu-
lations, it seems certain that this velocity must be a very small fraction of the
velocity of propagation in the most intense light or radiant heat which is pro-
pagated according to known laws. Denoting this velocity for the case of sun-
light at the earth’s distance from the sun by 2, and calling W the mass in pounds

60 PROFESSOR W. THOMSON ON THE POSSIBLE DENSITY OF THE

of any volume of the luminiferous ether, we have for the mechanical value of the
disturbance in the same space,
Ws

g
where g is the number 32°2, measuring in absolute units of force, the force of

’

: 83 :
gravity on apound. Now we found above, from observation, y- for the mechani-

cal value, in foot-pounds, of a cubic foot of sunlight; and therefore the mass, in
pounds, of a cubic foot of the ether, must be given by the equation,

_ 32-2 83
Lia's oak
1 :
If we assume 0 = a V, this becomes
156892 X18 Bi yc stincsted WABI pats rn n2
W = —ys— *™ = 793000 x 5280)° *" = 3899 x 10 ;

and for the mass, in pounds, of a cubic mile we have

B22 08 ge

(192000) 2649 x 109-

It is quite impossible to fix a definite limit to the ratio which v may bear to V ;

but it appears improbable that it could be more, for instance, than 30, for any kind

of light following the observed laws. We may conclude that probably a cubic

foot of the luminiferous medium in the space traversed by the earth contains not

less than ease of a pound of matter, and a cubic mile not less than
i

1060 x 10° *

If the mean velocity of the vibrations of light within a spherical surface con-
centric with the sun and passing through the earth were equal to the earth’s
velocity—a very tolerable supposition—since this is zo175 of the velocity of light, the
whole mass of the luminiferous medium within that space would be 3oi59 of the
earth’s mass, since the mechanical value of the light within it, being as much as
the sun radiates in about 8 minutes, is about zs459 of the mechanical value of the ©
earth’s motion. As the mean velocity of the vibrations might be many times
greater than has been supposed in this case, the mass of the medium might be con-
siderably less than this ; but we may be sure it is not incomparably less, not
100,000 times as small for instance. On the other hand, it is worth remarking
that the preceding estimate shows that what we know of the mechanical value
of light renders it in no way probable that the masses of luminiferous medium in
interplanetary spaces, or all round the sun in volumes of which the linear dimen-
sions are comparable with the dimensions of the planets’ orbits, are otherwise
than excessively small in comparison with the masses of the planets.

But it is also worth observing) that the luminiferous medium is enormously
denser than the continuation of the terrestrial atmosphere would be in interplane-

LUMINIFEROUS MEDIUM, AND THE MECHANICAL VALUE OF SUNLIGHT. 61

tary space, if rarefied according to Boyue’s law always, and if the earth were at
rest in a space of constant temperature with an atmosphere of the actual density

at its surface.* Thus the mass of air in a cubic foot of distant space several times

1 Ib.

jaa 10% > While there can-
1 Ib.

not, according to the preceding estimate, be in reality less than jz¢9 7797 » Which

is 9 x 10" times as much, of matter in every cubic foot of space traversed by the
earth.

* “ Newron has calculated (Princ. ii., p. 512) that a globe of ordinary density at the earth’s
surface, of one inch in diameter, if reduced to the density due to the altitude above the surface of
one radius of the earth, would occupy a sphere exceeding in radius the orbit of Saturn.” —(Herschel’s
Astronomy, Note on § 559.) It would (on the hypothesis stated in the text) we may now say
occupy a sphere exceeding in radius millions of millions of times the distances of any stars of which
the parallaxes have been determined. A pound of the medium, in the space traversed by the earth,
cannot occupy more than the bulk of a cube 1000 miles in side. The earth itself, in moving through
it, cannot displace less than 250 pounds of matter.

the earth’s radius off, on this hypothesis, would be

VOL. XXI. PART I. R

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VII.—On the Mechanical Energies of the Solar System.
By Professor WILLIAM THOMSON.

(Read 17th April 1854.)

The mutual actions and motions of the heavenly bodies have long been
regarded as the grandest phenomena of mechanical energy in nature. Their
light has been seen, and their heat has been felt, without the slightest sus-
picion that we had thus a direct perception of mechanical energy at all. Even
after it has been shewn* that the almost inconceivably minute fraction of the Sun’s
heat and light reaching the earth is the source of energy from which all the me-
chanical actions of organic life, and nearly every motion of inorganic nature at
its surface, are derived, the energy of this source has been scarcely thought of as
a development of mechanical power.

Little more than ten years ago the true relation of heat to force, in every
electric, magnetic, and chemical action, as well as in the ordinary operations of —
mechanics, was pointed out ;{ and it is a simple corollary from this that the Sun,
within the historical period of human observation, has emitted hundreds of times
as much mechanical energy{ as that of the motions of all the known planets taken
together. The energy, that of light and radiant heat, thus emitted, is dissipated
always more and more widely through endless space, and never has been, pro-
bably never can be, restored to the Sun, without acts as much beyond the scope
of human intelligence as a creation or annihilation of energy, or of matter itself,
would be. Hence the question arises, What is the source of mechanical energy,
drawn upon by the Sun, in emitting heat, to be dissipated through space? In
speculating on the answer, we may consider whether the source in question con-
sists of dynamical energy, that is, energy of motion, § or of ‘“ potential energy,”
(as Mr Ranxine has called the energy of force acting between bodies, which will
give way to it unless held); or whether it consists partly of dynamical and partly
of potential energy.

And again, we may consider whether the source in question, or any part of
it, is in the Sun, or exists in surrounding matter, until taken and sent out again

* Herscuer’s Astronomy, Edition 1833.—See last Hd., § (399).

_ + Jovzsz “On the Generation of Heat in the Galvanic Circuit,” communicated to the Royal Society
of London, Dec. 17, 1840, and published, Phil. Mag., Oct. 1841. ‘‘ On the Heat evolved during
the Electrolysis of Water,” Literary and Phil. Soc. of Manchester, 1843, Vol. vii., Part 3., Second
Series. “ On the Calorific Effects of Magneto-Electricity, and the Mechanical Value of Heat,” com-
municated to the British Association, August 1843, and published, Phil. Mag., Sept. 1843. ‘* On
the Changes of Temperature produced by the Rarefaction and Condensation of Air,” commu-
nicated to the Royal Society, June 1844, and published, Phil. Mag., May 1845. Jouze and Scorrssy
“On the Powers of Electromagnetism, Steam, and Horses,’’ Phil. Mag., June 1846.

t Once every 20 years or so.—See Table of Mechanical Energies of the Solar System, appended.

§ “ Actual energy,” as Mr Ranxive has called it.
VOL. XXI. PART I. S

64 PROFESSOR W. THOMSON ON THE

by the Sun, or exists as energy only convertible into heat by mutual actions be-
tween the Sun and surrounding matter.

If it be dynamical and entirely in the Sun, it can only be primitive heat; if
potential and in the Sun, it can only be energy of chemical forces ready to act.
If not in the Sun, it must be due to matter coming to the Sun; (for it certainly is
not a mere communication of motion to solar particles from external energy, as
such could only be effected by undulations like sound or radiant heat, and we
know that no such anti-radiation can be experienced by a body in the Sun’s cir-
cumstances) ; but whether intrinsically in such external matter, or developed by
mutual action between this matter and the Sun, and whether dynamical or poten-
tial in either case, requires careful consideration, as will be shewn in the course
of this communication. We see, then, that all the theories which have been yet
proposed, as well as every conceivable theory, must be one or other, or a combina-
tion of the following three :—

I. That the Sun is a heated body, losing heat.

II. That the heat emitted from the Sun is due to chemical action among ma-
terials originally belonging to his mass, or that the Sun is a great fire.

III. That meteors falling into the Sun give rise to the heat which he emits.

In alluding to theories of solar heat in former communications to the Royal
Society, I pointed out that the first hypothesis is quite untenable. In fact, it is
demonstrable that, unless the Sun be of matter inconceivably more conductive for
heat, and less volatile, than any terrestrial meteoric matter we know, he would be-
come dark in two or three minutes, or days, or months, or years, at his present
rate of emission, if he had no source of energy to draw from but primitive heat.*
The second has been not only held by the Fire-worshippers, but has probably been
conceived of by all men in all times, and considered as more or less probable by
every philosopher who has ever speculated on the subject. The third may have
occurred at any time to ingenious minds, and may have occurred and been set
aside as not worth considering; but was never brought forward in any definite
form, so far as Iam aware, until Mr WavTERsTON communicated to the British
Association, during its last meeting at Hull, a remarkable speculation on cosmical
dynamics, in which he proposed the Theory that solar heat is produced by the im-
pact of meteors falling from extra-planetary space, and striking his surface with

* This assertion is founded on the supposition that conduction is the only means by which
heat could reach the Sun’s surface from the interior, and perhaps requires limitation. For it might
be supposed that, as the Sun is no doubt a melted mass, the brightness of his surface is constantly
refreshed by incandescent fluid rushing from below to take the place of matter falling upon the sur-
face after becoming somewhat cooled and consequently denser—a process which might go on for many
years without any sensible loss of brightness. If we consider, however, the whole annual emission
at the present actual rate, we find, even if the Sun’s thermal capacity were as great as that of
an equal mass of water, that his mean temperature would be lowered by about 3° cent. in two years.
We may, I think, safely conclude that primitive heat within the Sun is not a sufficient source for the
emission which has continued without sensible (if any) abatement for 6000 years.—(May 4, 1854.)

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 65

velocities which they have acquired by his attraction. This is a form of what may
be called the Gravitation Theory of Solar Heat, which is itself included in the
general meteoric theory.

The objects of the present communication are to consider the relative capa-
bilities of the second and third hypothesis to account for the phenomena; to ex-
amine the relation of the gravitation theory to the meteoric theory in general ; and
to determine what form of the gravitation theory is required to explain solar
heat consistently with other astronomical phenomena.

In the first place, it may be remarked, that in all probability there must always
be meteors falling into the Sun, since the fact of meteors coming to the earth*
proves the existence of such bodies moving about in space ; and even if the mo-
tions of these bodies are at any instant such as to correspond to elliptical or
circular orbits round the Sun, the effects of the resisting medium would gra-
dually bring them in to strike his surface. Also, it is easy to prove dynamically
that meteors falling in to the Sun, whatever may have been their previous state
of motion, must enter his atmosphere, or strike his surface, with, on the whole,
immensely greater relative velocities than those with which meteors falling to the
earth enter the earth’s atmosphere, or strike the earth’s surface. Now, JouLe has |
shewn what enormous quantities of heat must be generated from this relative
motion in the case of meteors coming to the earth; and by his explanation} of
“ falling stars,” has made it all but certain that, in a vast majority of cases, this
generation of heat is so intense as to raise the body in temperature gradually
up to an intense white heat, and cause it ultimately to burst into sparks in the
air (and burn if it be of metallic iron) before it reaches the surface. Such effects
must be experienced to an enormously greater degree before reaching his surface,
by meteors falling to the Sun, if, as is highly probable, he has a dense atmosphere ;
or they would take place yet more intensely on striking his solid or liquid surface,
were they to reach it still possessing great velocities. Hence, it is certain that
some heat and light radiating from the Sun is due to meteors. It is excessively
probable that there is much more of this from any part of the Sun’s surface than
from an equal area of the earth’s, because of the enormously greater action that
an equal amount of meteoric matter would produce in entering the Sun, and. be-
cause the Sun, by his greater attraction, must draw in meteoric matter much more
copiously with reference to equal areas of surface. We would have no right then,
as was done till Mr Waterston brought forward his theory, to neglect meteoric
action in speculating on solar heat, unless we could prove, which we certainly

* To make the argument perfectly conclusive, it would have to be assumed that meteors not
only are, but have been, always falling to the earth for some immense period of time. The conclu-
sion, however, appears sufficiently probable with the facts we know.

+ See Philosophical Magazine, May 1848, for reference to a lecture in Manchester, on the 28th
April 1847, in which Mr Joutz said, that «the velocity of a meteoric stone is checked by the atmo-
sphere and its vis viva converted into heat, which at last becomes so intense, as to melt the body and
dissipate it in fragments too small probably to be noticed in their fall to the ground, in most cases.”

66 PROFESSOR W. THOMSON ON THE

cannot do, that its influence is insensible. It is in fact not only proved to exis
as a cause of solar heat, but it is the only one of all conceivable causes which we
know to exist from independent evidence.

To test the possibility of this being the principal or the sole cause of the phe-
nomenon, let us estimate at what rate meteoric matter would have to fall on the
Sun, to generate as much heat.as is emitted. According to PovILLEt’s data.* -06 of
a thermal unit centigrade is the amount of heat incident per second on a square
foot directly exposed to solar radiation at the Earth’s distance from the Sun, which
being 95,000,000 miles, and the Sun’s radius being 441,000 miles, we infer that
the rate of emission of heat from the Sun is

ee neces

2
“441,000 ) = 2781 thermal units per second

per square foot of his surface.
The mechanical value of this (obtained by multiplying it by Joute’s equivalent,
aay a 95,000,000
aR (aoa
Now if, as Mr WaTERSTON supposes, a meteor either strikes the Sun, or enters an
atmosphere where the luminous and thermal excitation takes place, without having
previously experienced any sensible resistance, it may be shewn dynamically (the
velocity of rotation of the Sun’s surface, which at his equator is only a mile and a
quarter per second, being neglected) that the least relative velocity which it can
have is the velocity it would acquire by solar gravitation in falling from an infi-
nite distance, which is equal to the velocity it would acquire by the action of a
constant force equal to its weight at the Sun’s surface, operating through a space
equal to his radius. The force of gravity at the Sun’s surface being about 28
times that at the earth's surface, this velocity is

2x 28 x 32:2 x 441,000
5280

value per pound of meteoric matter is
28 x 441,000 x 5280 = 65,000,000,000 ft. lbs.

Hence the quantity of meteoric matter that would be required, according to Mr
WateErston’s form of the Gravitation Theory, to strike the Sun per square foot is
0:000060 pounds per second (or about a pound every five hours.) At this rate
the surface would be covered to a depth of thirty feet in a year, if the density of
the deposit is the same as that of water, which is a little less than the mean
density of the Sun.} A greater rate of deposit than this could not be required,
if the hypothesis of no resistance, except in the locality of resistance with lumi-
nous reaction, were true; but a less rate would suffice if, as is probable enough,

2
) = 386,900 ft. Ibs:

= 390 miles per second; and its mechanical

* Mémoire sur la Chaleur Solaire, &c., Paris 1838; See Comptes Rendus, July 1838; or
Povrtier, Traité de Physique, vol. ii.

+ This is rather more than double the estimate Mr Warersron has given. The velocity of
impact which he has taken is 545 miles per second, in the calculation of which, unless I am mistaken,
there must be some error.

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 67

the meteors in remote space had velocities relative to the Sun not incomparably
smaller than the velocity calculated above as due to solar gravitation.

But it appears to me that the hypothesis of no sensible resistance until the
* Sun’s atmosphere” is reached, or the Sun’s surface struck, is not probable ;* be-
cause if meteors were falling in to the Sun in straight lines, or in parabolic or
hyperbolic paths, in anything like sufficient quantities for generating all the heat
hé emits, the earth in crossing their paths would be, if not intolerably pelted, at
least struck much more copiously by meteors than we can believe it to be from
what we observe ; and because the meteors we see appear to come generally in
directions corresponding to motions which have been elliptic or circular, and
rarely if ever in such directions as could correspond to previous parabolic, hyper-
bolic, or rectilineal paths towards the Sun. If this opinion and the first men-
tioned reason for it be correct, the meteors containing the stores of energy for
future Sun light must be principally within the earth’s orbit : and we actually see
them there as the “ Zodiacal Light,” an illuminated shower or rather tornado of
stones (HERSCHEL, § 897). The inner parts of this tornado are always getting caught
in the Sun’s atmosphere, and drawn to his mass by gravitation. The bodies in
all parts of it, in consequence of the same actions, must be approaching the Sun,
although but very gradually ; yet, in consequence of their comparative minuteness,
much more rapidly than the planets. The outer edge of the zodiacal light ap-
pears to reach to near the earth at present (HERSCHEL, § 897); and in past times
it may be that the earth has been in a dense enough part of it to be kept hot,
just as the Sun is now, by drawing in meteors to its surface.

According to this form of the gravitation theory, a meteor would approach the
Sun by a very gradual spiral, moving with a velocity very little more than that
corresponding to a circular path at the same distance, until it begins to be much
more resisted, and to be consequently rapidly deflected towards the Sun; then
the phenomenon of ignition commences; after a few seconds of time all the
dynamical energy the body had at the commencement of the sudden change is
converted into heat and radiated off; and the mass itself settles incorporated in
the Sun. It appears, therefore, that the velocity which a meteor loses in en-

tering the Sun is that of a satellite at his surface, which (being +5 of that due

to gravitation from an infinite distance) is 276 miles per second. The mechanical
value (being half that of a body falling to the Sun from a state of comparatively
slow motion in space) is about 32,500,000,000 ft. lb. per pound of meteoric matter ;
hence the fall of meteors must be just twice that which was determined above
according to Mr WatrrstTon’s form of the theory, and must consequently amount
to 3800 Ibs. annually per square foot. If, as was before supposed, the density of
the deposit is the same as that of water, the whole surface would be covered

* For a demonstration that it is not possible, see Addition No. 1.
VOL. XXI, PART I. T

68 PROFESSOR W. THOMSON ON THE

annually to a depth of 60 feet, from which the Sun would grow in diameter by a
mile in 88 years. It would take 4000 years at this rate to grow a tenth ofa second
in apparent. diameter, which could scarcely be perceived by the most refined of
modern observations, or 40,000 years to grow 1”, which would be utterly insensi-
ble by any kind of observation (that of eclipses included) unassisted by powerful
telescopes. We may be confident, then, that the gradual augmentation of the
Sun’s bulk required by the meteoric theory to account for this heat, may have
been going on in time past during the whole existence of the human race, and yet
could not possibly have been discovered by observation, and that at the same
rate it may go on for thousands of years yet without being discoverable by the
most refined observations of modern astronomy. It would take, always at the
same rate, about 2,000,000 years for the Sun to grow in reality as much as he
appears to grow from June to December by the variation of the earth’s distance,
which is quite imperceptible to ordinary observation. This leaves for the specu-
lations of geologists on ancient natural history a wide enough range of time with a
Sun not sensibly less than our present luminary: Still more, the meteoric theory
affords the simplest possible explanation of past changes of climate on the earth.
For a time the earth may have been kept melted by the heat of meteors striking
it. A period may have followed when the earth was not too hot for vegetation,
but was still kept, by the heat of meteors falling through its atmosphere, at a
much higher temperature than at present, and illuminated in all regions, polar
as well as equatorial, before the existence of night and day. Lastly; although a
very little smaller, the Sun may have been been at some remote period much
hotter than at present by having a more copious meteoric supply.

A dark body of dimensions such as the Sun, in any part of space, might, by
entering a cloud of meteors, become incandescent as intensely in a few seconds as
it could in years of continuance of the same meteoric circumstances; and on again
getting to a position in space comparatively free from meteors, it might almost as
suddenly become dark again. It is far from improbable that this is the explana-
tion of the appearance and disappearance of bright stars, and of the strange va-
riations of brilliancy of others which have caused so much astonishment.*

The amount of matter, drawn by the Sun in any time from surrounding space,
would be such as in 474 years to amount to a mass equal to that of the earth.
Now there is no reason whatever to suppose that 100 times the earth’s mass
drawn in to the Sun, would be missed from the zodiacal light (or from meteors
revolving inside the orbit of Mercury, whether visible as the “ zodiacal light” or
not); and we may conclude that there is no difficulty whatever in accounting for
a constancy of solar heat during 5000 years of time past or tocome. Even physi-
cal astronomy can raise no objection by shewing that the Sun’s mass has not ex-

* The star which Mr Hinp discovered in April 1848, and which only remained visible for a few

weeks, during which period it varied considerably in appearance and brightness, but was always of

a ‘“‘ruddy” colour, may have not experienced meteoric impact enough to make its surface more
than red hot.

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 69

perienced such an augmentation ; for according to the form of the gravitation theory
which I have proposed, the added matter is drawn from a space where it acts on
the planets with very nearly the same forces as when incorporated in the Sun.
This form of the gravitation theory then, which may be proved to require a
greater mass of meteoric matter to produce the solar heat than would be required
on any other assumption that could be made regarding the previous positions
and motions of the meteors, requires not more than it is perfectly possible does
fall in to the Sun. Hence I think we may regard the adequacy of the meteoric
theory to be fully established.

Let us now consider how much chemical action would be required to produce
the same effects, with a view both to test the adequacy of the theory that the
Sun is merely a burning mass without a supply of either fuel or dynamical energy
from without, and to ascertain the extent to which, in the third theory, the com-
bustion of meteors may contribute, along with their dynamical energies, to the
supply of solar heat. Taking the former estimate, 2781 thermal units centigrade,
or 3,869,000 foot-lbs. as the rate per second of emission of energy from a square
foot of the Sun’s surface, equivalent to 7000 horse power, we find that more than
‘42 of a lb. of coal per second, or 1500 lbs. per hour would be required to produce
heat at the same rate. Now if all the fires of the whole Baltic fleet were heaped
up and kept in full combustion, over one or two square yards of surface, and if
the surface of a globe all round had every square yard so occupied, where could
a sufficient supply of air come from to sustain the combustion? yet such is the
condition we must suppose the Sun to be in, according to the hypothesis now
under consideration, at least if one of the combining elements be oxygen or any
other gas drawn from the surrounding atmosphere. If the products of combus-
tion were gaseous, they would in rising check the necessary supply of fresh air ;
or if they be solid or liquid (as they might be wholly or partly if the fuel be
metallic) they would interfere with the supply of the elements from below. In
either or in both ways the fire would be choked, and I think it may be safely
affirmed that no such fire could keep alight for more than a few minutes, by any
conceivable adaptation of air and fuel. If then the Sun be a burning mass, it
must be more analogous to burning gunpowder than to a fire burning in air ; and
it is quite conceivable that a solid mass, containing within itself all the elements
required for combustion, provided the products of combustion are permanently
gaseous,* could burn off at its surface all round, and actually emit heat as co-
piously as the Sun. Thus an enormous globe of gun-cotton might, if at first cold,
and once set on fire round its surface, get to a permanent rate of burning, in
which any internal part would become heated by conduction, sufficiently to
ignite, only when nearly approached by the diminishing surface. It is highly
probable indeed that such a body might for a time be as large as the Sun, and
give out luminous heat as copiously, to be freely radiated into space, without suf-

* On this account gunpowder would not do.

70 PROFESSOR W. THOMSON ON THE

fering more absorption from its atmosphere of transparent gaseous products* than
the light of the Sun actually does experience from the dense atmosphere through
which it passes. Let us therefore consider at what rate such a body, giving out
heat so copiously, would diminish by burning away. The heat of combustion
could probably not be so much as 4000 thermal units per pound of matter burned,t+
the greatest thermal equivalent of chemical action yet ascertained falling con-
siderably short of this. But 2781 thermal units (as found above) are emitted per
second from each square foot of the Sun; hence there would be a loss of about
‘7 of a pound of matter per square foot per second. Such a loss of matter from
every square foot, if of the mean density of the Sun (a little more than that of
water), would take off from the mass a layer of about ‘5 of a foot thick in a
minute, or of about 55 miles thick in a year. At the same rate continued, a
mass as large as the Sun is at present would burn away in 8000 years. If the
Sun has been burning at that rate in past time, he must have been of double
diameter, of quadruple heating power, and of eight-fold mass, only 8000 years
ago. We may quite safely conclude then that the Sun does not get its heat by
chemical action among particles of matter primitively belonging to his own mass,
and we must therefore look to the meteoric theory for fuel, even if we retain the
idea of a fire. Now, according to ANDREws, the heat of combustion of a pound
of iron in oxygen gas is 1301 thermal units, and of a pound of potassium in chlo-
rine 2655; a pound of potassium in oxygen 1700 according to JouLE; and carbon
in oxygen, according to various observers, 8000. The greatest of these numbers,
multiplied by 1390 to reduce to foot-pounds, expresses only the 6000th part, ac-
cording to Mr WaterstTon’s theory, and, according to the form of the Gravitation
Theory now proposed, only the 3000th part, of the least amount of dynamical
energy a meteor can have on entering the region of ignition in the Sun’s atmo-
sphere. Hence a mass of carbon entering the Sun’s atmosphere, and there burn-
ning with oxygen, could only by combustion give out heat equal to the 3000th
part of the heat it cannot but give out from its motion. Probably no kind of
known matter (and no meteors reaching the earth have yet brought us decidedly
new elements) entering the Sun’s atmosphere from space, whatever may be its
chemical nature, and whatever its dynamical antecedents, could emit by combus-
tion as much as joo9 of the heat inevitably generated from its motion. It is
highly probable that many, if not all, meteors entering the Sun’s atmosphere do
burn, or enter into some chemical combination with substances which they meet.
Probably meteoric iron comes to the Sun in enormous quantities, and burns in
his atmosphere just as it does to the earth. But (while probably nearly all the
heat and light of the sparks which fly from a steel struck by a flint is due to com-
bustion alone) only ;g455 part of the heat and light of a mass of iron entering the

* These would rise and be regularly diffused into space.

_ { Both the elements that enter into combination are of course included in the weight of the burn-
img matter.

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 71

Sun’s atmosphere or 7th of the heat and light of such a meteor entering our own,
can possibly be due to combustion. Hence the combustion of meteors may be
quite disregarded as a source of solar heat.

At the commencement of this communication, it was shown that the heat ra-
diated from the Sun is either taken from a stock of primitive solar heat, or ge-
nerated by chemical action among materials originally belonging to his mass, or
due to meteors falling in from surrounding space. We saw that there are suffi-
cient reasons for utterly rejecting the first hypothesis ; we have now proved that
the second is untenable; and we may consequently conclude that the third is true,
or that meteors falling in from space give rise to the heat which is continually
radiated off by the Sun. We have also seen that no appreciable portion of the
heat thus produced is due to chemical action, either between the meteors and
substances which they meet at the Sun, or among elements of the meteors them-
selves; and that whatever may have been their original positions or motions re-
latively to one another or to the Sun, the greater part of them fall in gradually
from a state of approximately circular motion, and strike the Sun with the ve-
locity due to half the potential energy of gravitation lost in coming in from an
infinite distance to his surface. ‘The other half of this energy goes to generate
heat very slowly and diffusely in the resisting medium. Many a meteor, how-
ever, we cannot doubt, comes in to the Sun at once in the course of a rectilineal
or hyperbolic path, without having spent any appreciable energy in the resisting
medium; and, consequently, enters the region of ignition at his surface with a
velocity due to the descent from its previous state of motion or rest, and there
converts both the dynamical effect of the potential energy of gravitation, and the
energy of its previous motion, if it had any, into heat which is instantly radiated
off to space. But the \peasons stated above make it improbable that more than
a very small fraction of the whole solar heat is obtained by meteors coming in
thus directly from extra-planetary space.

In conclusion, then, the source of energy from which solar heat is derived is
undoubtedly meteoric. It is not any intrinsic energy in the meteors themselves,
either potential, as of mutual gravitation or chemical affinities among their ele-
ments; or actual, as of relative motions among them. It is altogether de-
pendent on mutual relations between those bodies and the Sun. A portion of it,
although very probably not an appreciable portion, is that of motions relative to
the Sun, and of independent origin. The principal source, perhaps the sole ap-
preciably efficient source, is in bodies circulating round the Sun at present inside
the earth’s orbit, and probably seen in the sunlight by us and called “ The Zo-
diacal Light.” The store of energy for future sunlight is at present partly dy-
namical, that of the motions of these bodies round the Sun; and partly potential,
that of their gravitation towards the Sun. This latter is gradually being spent,
half against the resisting medium, and half in causing a continuous increase of
the former. Each meteor thus goes on moving faster and faster, and getting

VOL. XXI. PART I. U

72 PROFESSOR W. THOMSON ON THE

nearér and nearer the centre, until some time, very suddenly, it gets so much
entangled in the solar atmosphere, as to begin to lose velocity. In a few seconds
more, it is at rest on the Sun’s surface, and the energy given up is vibrated in a
minute or two across the district where it was gathered during so many ages,
ultimately to penetrate as light the remotest regions of space.

Explanation of Tables.

The following Tables exhibit the principal numerical data regarding the Mechanical Energies of
the Solar System.

In Table I., the mass of the Earth is estimated on the assumption that its mean density is five
times that of water, and the other masses are shown in their true proportions to that of the Earth,
according to data which Professor P1azz1 Smytu has kindly communicated to the author.

In Table II., the mechanical values of the rotations of the Sun and Earth are computed on the
hypothesis, that the moment of inertia of each sphere is equal the square of its radius multiplied
by only one-third of its mass, instead of two-fifths of its mass as would be the case if its matter were
of uniform density. These two estimates are only introduced for the sake of comparison with other
mechanical values shown in the Table, not having been used in the reasoning.

The numbers in the last column of Table II., showing the times during which the Sun emits
quantities of heat mechanically equivalent to the Earth’s motion in its orbit, and to its motion of
rotation, were first communicated to the Royal Society on the 9th January 1852, in a paper “ On
the Sources Available to Man for the production of Mechanical Effect.” These, and the other num-
bers in the same column, are the only part of the numerical data either shown in the Tables, or used
directly or indirectly in the reasoning on which the present theory is founded, that can possibly re-
quire any considerable correction ; depending as they do on M. Povirzer’s estimate of Solar Heat in
thermal units. The extreme difficulties in the way of arriving at this estimate, notwithstanding the
remarkably able manner in which they have been met, necessarily leave much uncertainty as to the
degree of accuracy of the result. But even if it were two or three times too great or too small, (and
there appears no possibility that it can be so far from the truth), the general reasoning by which the
Theory of Solar Heat at present communicated is supported, would hold with scarcely altered force.

The mechanical equivalent of the thermic unit, by which the Solar radiation has been reduced
to mechanical units is Mr Jouxe’s result—1390 foot-pounds for the thermal unit centigrade—which
he determined by direct pp with so much accuracy, that any correction it may be found to
require can scarcely amount to 335 or 33, of its own value.

TABLE J. FORCES and MOTIONS in the SOLAR SYSTEM.

Bich Forces of attraction |
Masses in pounds. Distances from the Sun’s towards the Sun, in Velocities, in miles
centre, in miles. terrestrial pounds. per second.
SUM) ly ssatees 4,230,000,000 x 10") (surface) 441,000 | 28-61 per lb. of matter| (equator) 1:27
Tmagimer y poled |
planet close to 1x 207 441,000 286,100 x 10" 277
the Sun, .
Mercury, . . 870 x 1071 36,800,000 50,110 30°36
Venusy 00092 | 10,530 x 107! 68,700,000 124,200 x 10” 22:22
| Earth, Ata haerdl 11,920 x 107} 95,000,000 73,490 x 10" 18°89
| Mars, apie os 1,579 x 107! 144,800,000 ADT Ie LQ? 15:28
Jupiernt ''2 4,037,000 x 107! | 494,300,000 919,400 x 10" 8:28
Saturn, cd as 1,208,000 x 107! 906,200,000 81,855 x 1017 611
Uranus, . . 201,490 x 102!) 1,822,000,000 3.377 x 1027 4:31
Neptune, . . 236,380 x 107! | 2,854,000,000 1,615 x 10” 3°44
Distances from Earth’s | Attraction towards Harth | Velocities relatively to
centre. in terrestrial pounds. | Harth’s centre, in miles.
Moon, , . 136 x 107 237,000 378% 10% 0-615
Earth’s equator, 3,956 -| 1 per Ib, of matter. 0-291

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 73

TABLE II. MECHANICAL ENERGIES of the SOLAR SYSTEM.

Potential Energy of gravitation to Actual Energy relatively to Sun’s centre.
Sun’s surface.
Equivalent to supply of Equivalent to supply
In f a Solar Heat, at the present Treat a of Solar Heat, at the
n foot-pounds. rate of radiation for a Ry eee es present rate of
period of radiation for a period of
>. 967,000 x 10” 116 yrs. 6 days.
Imaginary planet,
21
of 10% Ib. of 0 0 333 x 10” 1-44 ---
matter, close to
the Sun,
Mercury, . . o7 x LO* 6 yrs. 214 days 347 x 10 15-2
Wiens, .... 0+. 697 x 10% ao wPR 22s 25262 x 10% 98-5
Co 790 x 10% 94 oO omer 1,843 x 10° 80°7
ss 105 x 10% DOT ee oe 160 x 10” 7:0
Jupiter, . .| 268,800 x 10 | 32,240 119,980 x 10” 14 yrs. 144
Saturn, oe 80,440 x 10 | 9,650 19,580 x 10” Decne D7.
Wranus;. . . 13,430 x 10% 1,610 1625 x10” (hig
Neptune, . . 15,750 x 10% 1,890 L217 x 10" 53'°3
To the Earth’s surface. Relatively to Earth’s centre.
‘co... 2,846 x 1027 3-0 hours 2,347 x 10% 1:48 minutes
Earth (rotation), 14,310 x 10” 9:03
Vota. . .-|, 380,000 x 10% 45,589 years 1,114,004 x 10 134 years.

AppITIONS (May 9, 1854), No. I. Conclusion of Physical Astronomy against the Extra-
planetary Meteoric Theory.

Meteors which when at great distances possessed, relatively to the centre of
gravity of the solar system, velocities not incomparably smaller than the velo-
city due to gravitation to the Sun’s surface, must strike the surfaces of the
earth and of the other planets not incomparably less frequently than equal areas
of the Sun’s surface, and with not incomparably smaller velocities, and conse-
quently must generate heat at the surfaces of the earth and other planets not in-
comparably less copiously than at equal areas of the Sun’s surface. But the whole
heat emitted from any part of the Sun’s surface is incomparably greater than all
that is generated by meteors on an equal area of the earth’s surface, and there-
fore is incomparably greater than all that can be generated at his own surface
by meteors coming in with velocities exceeding considerably the velocity due
to his attraction from an infinite distance. Hence upon the extra-planetary
Meteoric Theory of Solar Heat the quantity of matter required to fall in cannot
be much, if at all, less than that required upon the hypothesis that the work done
by the Sun’s attraction is equal to the mechanical value of the heat emitted from
his surface, and must therefore be, as found above, about -000060 of a pound per
square foot per second, or 1900 lb. per square foot in a year. The mean density

74 PROFESSOR W. THOMSON ON THE

of the Sun being about 14 times that of water, the matter in a pyramidal por-
tion from his centre to a square foot of his surface is about

1 x 441,000 x 5280 x 11 x 64 = 62,100,000,000 Ib.

and the whole annual addition of meteoric matter to the Sun would there-

fore be
1900 1

62,100,000,000 — 32,400,000

of his own mass. In about six thousand years the Sun would therefore be aug-
mented by sap in mass from extra-planetary space. Since the time occupied by
each meteor in falling to the Sun from any distance would be much less than
the periodic time of a planet revolving at that distance, and since the periodic
times of the most distant of the planets is but a small fraction of 6000
years, it follows that the chief effect on the motions of the planetary system pro-
duced during such a period by the attraction of the matter falling in would be
that depending simply on the augmentation of the central force. To determine
this, let M be the Sun’s mass at any time ¢, measured from an epoch 6000 years
ago; # the Earth’s mean angular velocity, and a its mean distance at the same
time; and 2 / the constant area described by its radius vector per second. Then
we have—

or a= = , (centrifugal force)
wa? =h; (equable description of areas)
from which we deduce,
2
yaers
and a _ Mt :

Now, if M, denote the mass of the sun at the epoch from which time is reckoned ;
since the annual augmentation is abcut 55;;)559 of the mass itself, we have

t
al ( ASE 39200-0060) ,
Qt
and 2— V2 ‘Si aigily
ae (1 4 eek

Hence, if o, and 9, denote the angular velocities at the epoch and at the present
time, T; the angular velocity, which is uniformly accelerated during the interval,
will have a mean value, o, expressed as follows :—

o=3 (a+ a) =o {1-§ SE} <9. (1 — sham ;
Qy 32,400,000/7 ’

and if © denote the angle described in the time T, we have

eg
@ =O, (z oy ee
soa

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 7d

To test this conclusion for the case of the earth, let T’ denote the number of re-
volutions round the Sun in the time T. Then, if the unit in which T is measured
be the time of a revolution with the angular velocity o,, we have

iy ye ana ail
~ ~ ~~ 32,400,000.
Thus, if T be 4000 years, we have
sad _ 16,000,000 _ -
T = 4000 — spo 000 = 399985

or only 3999} actual years in a period of 4000 times the present year. Similarly,
we should find a loss of $ of a year on a period of 2000 years ago; that is, of
about a month and a-half since the Christian era. Thus, if we reckon back about
2000 times the number of days at present in the year, we should find seasons,
new and full moons, and eclipses, a month and a half later than would be if the
year had been constantly what it is. Now we have abundant historical evidence
that there is no such dislocation as this, either in the seasons, or in the lunar
phenomena ; and it follows that the central attracting mass of the solar system
does not receive the augmentation required by the extra-planetary meteoric
theory of solar heat. But the reasoning in the preceding paper establishes, with
very great probability, a meteoric theory of Solar Heat ; and we may therefore
conclude that the meteors supplying the Sun with heat have been for thousands
of years far within the Earth’s orbit.

No. II. Friction between Vortices of Meteoric Vapour and the Sun’s Atmosphere the
immediate Cause of Solar Heat.

It has been shown that the meteors which contribute the energy for Solar Heat
must be for thousands of years within the Earth’s orbit before falling to the Sun.
But a meteor could not remain for half a year there, unless it were revolving round
the Sun, with at each instant the elements of a circular or elliptic orbit. Hence,
meteors, on their way in to the Sun, must revolve, each thousands of times round
him, in orbits which, whatever may have been their primitive eccentricities, must
tend to become more and more nearly circular as they become smaller by the

effects of the resisting medium. The resistance must be excessively small, even
very near the Sun ; since a body of such tenuity as a comet, darting at the rate
of 365 miles per second within one-seventh of his radius from his surface, comes
away without sensible loss of energy. If, as is probable, the atmosphere of that
part of space is carried in a vortex round the Sun by the meteors and other
planets, it may be revolving at nearly the same rates as these bodies at different
distances in the principal plane of the solar system; but we cannot conceive it

to be revolving in any locality more rapidly than a planet at the same distance.
VOL. XX. PART I. x

76 PROFESSOR W. THOMSON ON THE

At one-seventh of the Sun’s radius from his surface, this would be about 258
miles per second ; and, therefore, a comet approaching so near the Sun, could not
have a less velocity relatively to the resisting medium than 107 miles per second,
and, if going against the stream, might have as great a relative velocity as 623
miles. On the other hand, the great body of the meteors circulating round the
Sun, and carrying the resisting medium along with them, may be moving through
it with but small relative velocities ; the smaller for each individual meteor, the
smaller its dimensions. The effects of the resistance must, therefore, be very
gradual in bringing the meteors in to the Sun, even when they are very near his
surface; and we cannot tell how many years, or centuries, or thousands of years,
each meteor, according to its dimensions, might revolve within a fraction of the
Sun’s radius from his surface, before falling in, if it continued solid ; but we may
be sure that it would so revolve long enough to take, in its outer parts at least,
nearly the temperature of that portion of space; and therefore, probably, unless
it be of some substance infinitely less volatile than any terrestrial or meteoric
matter known to us, long enough to be wholly converted into vapour: (the mere
fact of a comet* escaping from so near the Sun as has been stated, being enough
to show that there is, at such a distance, no sufficient atmospheric pressure to
prevent evaporation with so high a temperature). Even the planet Mercury, if the
Sun is still bright when it falls in, will, in all probability, be dissipated in vapour
long before it reaches the region of intense resistance; instead of (as it would
inevitably do if not volatile) falling in solid, and in a very short time (perhaps a
few seconds) generating three years’ heat, to be radiated off in a flash which
would certainly scorch one half of the earth’s surface, or perhaps the whole, as
we do not know that such an extensive disturbance of the luminiferous medium
would be confined by the law of rectilineal propagation. Each meteor, when vola-
tilized, will contribute the actual energy it had before evaporation to a vortex
of revolving vapours, approaching the sun spirally to supply the place of the
inner parts, which, from moving with enormously greater velocities than the parts
of the Sun’s surface near them, first lose motion by intense resistance, emitting an
equivalent of radiant heat and light, and then, from want of centrifugal force, fall
in to the *un, and, consequently, become condensed to a liquid or solid state at his
surface, where they settle. The latent heat absorbed by the meteors in evaporation,
and afterwards partially emitted in their condensation at a higher temperature, is

* That a comet may escape with only a slight loss by evaporation, if the resistance is not too
great to allow it to escape at all, is easily understood, when we consider that it cannot be for more
than a few hours exposed to very intense heat (not more than two or three hours within a distance
equal to the Sun’s radius from his surface). If it consist of a cloud of solid meteors, the smallest
iragments may be wholly evaporated immediately ; but all whose dimensions exceed some very mo-
derate limit of a few feet would, unless kept back by the resisting medium and made to circulate
round the Sun until evaporated, get away with only a little boiled off from their surfaces,

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 77

probably as insensible, in comparison with the heat of friction, as it has been
shown the heat of any combustion or chemical action they can experience must be,
or as we have tacitly assumed the heat is which is taken and kept by the meteors
themselves in approaching from cold space to lodge permanently in the Sun. We
may conclude that the Sun’s heat is caused, not by solids striking him, or darting
through his atmosphere, but by friction in an atmosphere of evaporated meteors,
drawn in and condensed by gravitation while brought to rest by the resistance of
the Sun’s surface. The quantity of meteoric matter required, if falling in solid,
would, as we have seen, be such that half the work done by Solar Gravitation on
it, in coming from an infinite distance, is equal to the energy of heat emitted from
the Sun, and would, therefore, amount to a pound every 2°3 hours per square foot
of the Sun’s surface ; and it will be the same as this, notwithstanding the pro-
cess of evaporation and condensation actually going on, if, as appears probable
enough, the velocity of the vortex of vapour immediately external to the region
of intense resistance in all latitudes be nearly equal to that of a planet close to
the Sun.

No. III. On the Distribution of Temperature over the Sun’s Surface.

Not only the larger planets, but the great mass of meteors revolving round the
Sun, appear to revolve in planes nearly coinciding with his equator, and there-
fore such bodies, if solid when drawn in to the Sun, would strike him principally
in his equatorial regions, and would cause so much a more copious radiation of
heat from those regions than from any other parts of his surface, that the ap-
pearance would probably be a line or band of light, instead of the round, bright
disc which we see. The nearly uniform radiation which actually takes place from
different parts of the Sun’s surface appears to be sufficiently accounted for by the
distillation of meteors, which, we have seen, must, in all probability, take place
from an external region of evaporation at a considerable distance (perhaps several
times his radius) inwards to his surface where they are condensed. Whatever
be the dynamical condition of the luminous atmosphere of intense resistance, it
is clear that there must be a very strong tendency to an equality of atmospheric
pressure over the probably liquid surface of the Sun, and that the temperature
of the surface must be everywhere kept near that of the physical equilibrium be-
tween the vapours and the liquid or solid into which they are distilling. A lower-
ing of temperature in any part would therefore immediately increase the rate of
condensation of vapour into it, and so bring a more copious influx of meteoric
matter with dynamical energy to supply the deficiency of heat. The various
deviations from uniformity which have been observed in the Sun’s disc are pro-
bably due to eddies which must be continually produced throughout the
atmosphere of intense resistance between his surface (which at the equator
revolves only at the rate of 1-3 miles per second) and the great vortex of meteoric

78 PROFESSOR W. THOMSON ON THE

vapour, which a few miles outside revolves at the rate of 277 miles per second
about the equatorial regions, and (if not at the same) certainly at enormously great
rates a few miles from the Sun’s surface in other localities. Such eddies may
ordinarily be seen as the streaks which have been compared to ‘“ the streamers
of our northern lights” (HERscHEL, § 387), and when any one of them sends a root
down to the Sun’s surface it may cause one of the ‘‘ minute dark dots or pores”
which have been observed, and which, when attentively watched, are found to be
always changing in appearance (HERSCHEL). <A great rotatory storm, like the
tropical hurricanes in the earth’s atmosphere, may occasionally result from
smaller eddies accidentally combining, or from some disturbing cause origi-
nating at once an eddy on a much larger scale than usual, and may traverse the
Sun’s surface, preventing the distillation of meteoric vapour over a great area, and
consequently checking both the supply of dynamical energy for radiant heat in the
luminous atmosphere of resistance, and the torrents of condensed meteoric vapours
falling to the surface below it. The consequence would be, that the meteoric
rain (HerscHEL’s “ cloudy stratum,”’) would be cleared away for a certain space
under the central parts of the storm by falling down to the liquid or solid surface,
and the luminous atmosphere would lose intensity over a larger space bounded
very irregularly by a region of minor eddies, which would cause varying streaks
of light. These are exactly the circumstances assumed by Sir WitL1AM HERSCHEL
to account for the great spots with their dark centres surrounded by sharply
terminated penumbree inside the abrupt ragged boundaries of .the bright surface,
and the branching luminous streaks or “ faculee” in the bright surface outside
in their neighbourhood.—(Sir Joun HerscueE.’s Astronomy, § 388).

No. IV. (Added August 15, 1854.) On the Age of the Sun.

The moment of the Sun’s rotatory motion (according to the hypothesis men-
tioned above in the “ Explanation of the Tables” regarding the moment of inertia
of his mass) is one-third of his mass multiplied by his radius, multiplied by the
linear velocity of his equator; and is therefore equal to that of a planet at his
oie Yale
3x277 650
the quantity of meteoric matter which would fall in during 25,000 years, at the
present rate; and therefore 25,000 years is the time the Sun would take to acquire
his actual motion of rotation, by the incorporation of meteors, if these bodies were
each revolving in the plane of his equator immediately before entering the region
of intense resistance. But it has been shown to be probable that a great space
round the Sun is occupied by a vortex of evaporated meteors, and that the incor-
poration of meteoric matter takes place in reality by the condensation of vapour
in a stratum close to his surface all round. It appears not improbable that the

surface having a mass equal to of his own mass. This is equal to

MECHANICAL ENERGIES OF THE SOLAR SYSTEM. 79

tangential velocity of this vortex immediately external to the radiant region of in-
tense resistance may be found to be, in all solar latitudes, very nearly that ofa planet
close to the Sun. If it be so, the moment of the motion communicated to the Sun

by any mass of meteoric matter will be of what would be communi-

cated by the incorporation of an equatorial planet of equal mass: as much as 375
of the Sun’s mass would have to fall in to produce his present rotation: and
32,000 years would be the time in which this would take place, at the present rate
of meteoric incorporation as estimated above.

It will be a very interesting hydrodynamical problem, to fully investigate the
motion of the meteoric vortex; and among results to be derived from it will be
strict estimates of the contribution to the Sun’s rotatory motion, and of the quan-
tity of heat generated, by any amount of meteoric matter in becoming incorporated.
With these, and with an accurate determination of the rate at which the Sun ra-
diates heat, we should be able to fix, with certainty, the augmentation of his
velocity of rotation actually taking place at present from year to year, and to
estimate the time during which the existing rotation would be acquired by me-
teoric incorporation going on always at the present rate and in the present man-
ner. Whatever this time (which I shall call T years, to avoid circumlocution
below) may be, it probably will not be found to differ very widely from the pre-
ceding estimate of 32,000 years.

Now, from the fact that the Sun’s equator, the planets’ orbits, and the Zodia-
cal Light, all lie nearly in one plane, it appears highly probable that the Sun’s
present motion has really been acquired by the incorporation of meteors. It is
certain that the present manner and rate of meteoric action cannot have been
going on for more than the indicated period (T), without giving the Sun a greater
rotatory motion than he has, unless (which is very improbable) he were previously
rotating in a contrary direction round the same axis: and, at only the present
rate, it cannot have been going on for less than that time, unless the Sun has
been created with a rotatory motion round his present axis, or has acquired such
a motion from some independent mechanical action. The actual rate of Solar
radiation in time past may, for all we now know, have been sometimes much
greater and sometimes much less than at present; and there probably has been
a time before, when meteors in abundance fell direct to the Sun from extra-
planetary space, some getting stopped on their way by the Earth, and illuminating
it by friction in its atmosphere and impact at its surface. But the kind of me-
teoric action now going on, has in all probability produced neither more nor less
than T times the quantity of heat now emitted from the Sun in one year. All
things considered, it seems not improbable that the Earth has been efficiently illu-
minated by the Sun alone for not many times more or less than 32,000 years.

As for the future, it will be a most interesting problem to determine the mass

VOL. XXI. PART I. NY

80 ON THE MECHANICAL ENERGIES OF THE SOLAR SYSTEM.

of the Zodiacal Light (that is, matter external to the Sun’s mass, and within the
Earth’s orbit), by the perturbations it may probably enough be discovered to pro-
duce in the motions of the visible planets. It could scarcely, I think, amount to
36 of the Sun’s mass (probably not to nearly as much), without producing such
perturbations as could not have been overlooked in the present state of astrono-
mical science ; and we have seen that meteors amounting to z¢95 of the Sun's
mass, must, at the present estimated rate, fall in in 3000 years. I conclude that
Sunlight cannot last as at present for 300,000 years.

The continual acceleration of the Sun’s rotatory motion, which the preceding
theory indicates, must, sooner or later, be tested by direct observation. The rate
of acceleration (which for many thousands of years past and to come must remain
sensibly constant, if the solar radiation continues so), is such that the angular

velocity is increased annually by = of its present value. If T be 32,000, accord-

ing to the preceding conjectural estimate, the effect in 53 years would amount to
diminishing the period of the Sun’s revolution by an hour; and the actual effect
cannot, according to the theory. be incomparably greater or less. It is just pos-
sible that a careful comparison of early with recent observations on the apparent
motions of the dark spots may demonstrate this variation; but as some of the
most accurate of recent observations of this kind have led to estimates of the pe-
riod of revolution* differing from one another by as much as 8 hours, it is more
probable that, unless some way be discovered for taking into account the motions
of the spots themselves with reference to the mass, centuries will elapse before
direct evidence can be had either for or against the anticipated acceleration of
the Sun’s rotatory motion.

Days. Hours. Minutes.

* According to Boum, : ; 25 12 30
* LAvGIER, . : 25 8 10
- PETERSEN, . P 25 4 30

(See Encye. Brit., 8th edit. vol. iv., p. 87.) The discrepancies are probably due to proper motions
of the spots, which, from the explanation given above in Addition ill., may be expected to be very
considerable.

VII1.—On the Meteorology of the English Lake District, including the Results of
Experiments on the Fall of Rain, the Temperature, the Dew Point, and the
Humidity of the Atmosphere, at various heights on the Mountains, up to
3166 feet above the Sea Level,—for the years 1851, 1852, and 1858. By Joun
Fuercuer Minter, Ph. D., F.R.S., Fellow of the Royal Astronomical Society,
Associate of the Institution of Civil Engineers, Member of the British Meteoro-
logical Society, Corresponding Member of the Literary and Philosophical
Society of Manchester, &c.

(Communicated Ist May 1854.)

INTRODUCTORY REMARKS.

The experiments on the rain-fall in the lake district valleys were commenced
in 1844, the mountain gauges were planted in the spring of 1846,—the hygro-
metrical observations were instituted at the beginning of the year 1852,—and the
entire investigation was brought to a close at the end of the year 1853, when its
main objects were considered to have been satisfactorily answered and attained.

The tabular observations and general results of the inquiry up to the close of
the year 1850, were communicated to the Royal Society of London in four papers,
which are published in the Philosophical Transactions of that body. The fifth
and concluding paper (comprising the observations, &c. for the years 1851-53
inclusive) I have now the honour to present to the Royal Society of Edinburgh.

In all previous publications, I have thought it desirable to notice any acci-
dents or occurrences which interfered with the continuity of the experiments, or
which might affect the accuracy of the tabular or comparative results. As was
to be expected, from the great number of instruments in operation, and the ex-
posed situation of many of them, such mishaps, either designed or fortuitous, oc-
casionally occur; nor is the past triennial period exempted from its share of
casualties.

Early in February 1852, the Langdale Head Gauge was thrown into the river
by some mischievous person, and rendered useless; a new instrument was imme-
diately made and forwarded, which was stolen early in November the same year,
and the station was then abandoned.

On the 6th of March 1852, a new and extra strong metal bottle was forwarded
for the Stye Head Gauge. The old receiver, when examined at Whitehaven, was
found to be water-tight when perfectly upright or level, but it leaked very slowly
when placed on a slightly inclined surface. The loss by leakage at this station
during the winter of 1851-2, if any, must have been trifling.

VOL. XXI. PART I. Z

82 DR MILLER ON THE METEOROLOGY OF

The rain gauges used were 5 inches in diameter, and their height above the
ground was about 2 feet. They were all made under my own superintendence.
The receivers of the mountain gauges were capacious vessels made of extra heavy
copper double lapped at the seams, with the bottoms convex inwards, to enable
them more readily to resist the expansive force of the water during its conversion
into ice; they were calculated to hold 60 or 70 inches of rain.

The glass metres (Howarp’s) employed were graduated by Mr Bate of the
Poultry, or by his successor, Mr Porrer.

The Roman numerals at the head of the Tables refer to corresponding numbers
on a map of the Lake District, on which the gauges are laid down in small coloured
circles, each with its tabular number attached.

83

THE ENGLISH LAKE DISTRICT.

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[EQ] Ava_ OY} UI “OI “LOIMLSIG ANV'T HSITONY OY} UL NIVY JO TIV,.{ 04} JO SISAONAG—] AIAV

84 DR MILLER ON THE METEOROLOGY OF

TABLE II—WEtT Days.

Whitehaven.
The Flosh
Tarn Bank,
Cockermouth.
Bassenthwaite
Halls,
Keswick.
Loweswater
Lake.
Crummock Lake.
Wastdale Head.
Troutbeck.
Ambleside.
Bowness,
Westmoreland.
Langdale Head.
Seathwaite.
Stonethwaite.

January
February | 15] 15.) 44 \e03) 15 |) 14| 13) 16 pets eas 1s 16 |) fae
March . iby 22 16 20 19 21 21 26 19 19 22 22 22 21
April. 16 16 15 15 14 14 15 20 14 14 15 18 17 17
May. . 15 15 13 13 17 16 19 20 16 12 16 16 21 20
innate) 2 16 18 12 16 Le 17 20 16 15 16 20 20 17
July. me 13 15 15 23 18 14 15 15 17 14 ily 15 18 16
August . 18 18 19 17 18 19 19 19 19 17 19 19 19 19
September 8 9 7 8 9 9 9 8 8 7 | 20 8 9 8
October . 24 25 21 22 25 24 24 25 23 21 25 24 25 23
November | 16 14 16 12 16 13 15 17 11 9 14 16 15 13
December j

ee ee eee Eee eee ee

TABLE III.—Shewing the QuANTITY of RAIN received by the MOUNTAIN GAUGES,
in the year 1851.

No. xxt, | xxr2 | xxi. | xxur.| xxiv. | xxv xiv, | xm. | xxvi. | xxvur.| xrx.
©: $ 10 3 2 3 THE VALLEY. BoRROWDALE.
a8 A ae a oO Ew G4.

2 Ps aN > 2 a3
2 lee |e | ee Je) S23] 2 |eeelee Glee
wi. | #2 | 72 | ae | 2/58 | 8 |ER2/ePe/se2 |S | see
as |de|S65 | 33 | se | Be |=o2|228|.83 | si al aee
> 2 > > a2 RR Me loses Qos Cie moo SiS
me? | 2) 88 | es | HB | 22 1884 |Ss4| so las" | Tas
s$)2° |s8 | as | S° | £° |\e8ele2/see (22 lass
ae | 4 = = la a (Pe" ("8 jeaelee | ae
Inches Inches Inches. Inches. | Inches. Inches Inches Inches. Inches Inches. | Inches
January A bike Fy. 15-23 *6-90| 22-00} 14-40| 13:50} 14-47] 15-59} 26-90! 38-86] 28-63
February . . | tFr. Fr, |. Fr. | Fr. |» Fr.'| 9 Bre | 11-66) (7-05) 15-00| 17-36] 15-04
Mareh . . . i'r, 14-55 Fr. | 18-26] 16-26) 16-S6| 6-94] 5-36] 7-78] 9-93] 9-36
Aaril 23 ae Er 3-36| Er. 3-10| 4-36] 4-14] 4-16| 2-50] 5-07] 6-02] 6-08
May yee oh) aa 16889 5:50) 19-43 5-17 3-92 4-35 4-36 3-94 3-85| 4-72| 4-53
VMne? ae. 6-83 8-54 6:91} 10-92 7-80 8-20 8-90 6-97 | 11-79} 12-88) 11-63
July a oe §11-30 9-69 | 11-35| 14-00 9-71 8-98 9-01 7-78| 18-44] 19-12] 14-47
August . «| 10-80] 10-92} 11-22} 15-72) 12-60 8-95! 10-89 7-67| 13-36| 17-04] 13-16
September 6 4-72 5:75 4-08 4-90 5-56 5:62 3-79 6-30 4-13 5:86 4-30
October . . 9-1 1/ 11-00 8-81} 19-90] 16-11] 11-25) 14-74 9-16| 21-16} 23-45 | 20-38
November .j| Fr. je Fr. ines Fr. 4:08} 3-96| 2-15) 3-84] 4-89) 3-74
December 2 D640) We 75))) 12-530 tla 9-44 3-58 5-06 4-11} 10-10 9-49 7-99
Inches . . .| 71-29) 96-29] 81-23 |125-29 |100-16| 89-51| 97-94] 78-58 141-42 |169-62 139-60

* The Gabel Gauge was also frozen, and the funnel filled with snow ; the Receiver was brought down to the
valley and its contents liquefied.

+ February 28. The Mountain Gauges were all frozen up.

¢ May 31. The Sca Fell Gauge was frozen up for seven months, viz., from the latter part of October 1850,
till near the end of May 1851, an unusually long period. Snow fell on the tops so late as the 4th of June.

' The temperature was unnaturally low, rarely reaching 60°, till the 27th of June, when it suddenly rose to 77°
at the coast; and on the 28th, 29th and 30th, the thermometer attained to 82°, 83°-5, and 79°. At Seathwaite, the
maxima on these days were 79°, 79°, and 76°, respectively.

§ The return of rain on Sca Fell for July. is only 4:19 inches. The registrar says he cannot account for the
relative smallness of the quantity, unless it has been caused by partial thunder rains; but as I conceive no adequate
physical cause can be adduced for so great a deficiency, I have ventured to make the quantity nearly the same as
on the Gabel. :

|| Some ice left in Sca Fell and Gabel Gauges,— October 31st.

December 31. The Sca Fell and Gabel Receivers were brought down to the hamlet, and their frozen contents
liquefied.

THE ENGLISH LAKE DISTRICT. 85

TABLE 1V.—For the SuMMER MonrTus.

‘el
al
WH
is]
al
Kw
=)
<
A

XIV. XIII. XXVI. | XXVII. xIxX.

THE VALLEY. BoRROWDALE.

Sprinkling Tarn,
above the Sea.
above the Sea.

above the Sea.
1900 feet above Sea.

Seatollar
Common,1388

Brant Rigg, 924 feet
unknown,

ive]
eo)
ce
oD
a
“4
]
Au
i
i="
oD
Fy
=}
S
RM

feet above the Sea.
Lingmell, 1778 feet
Great Gabel, 2925
feet above the Sea.
Wastdale, 247
ft. above Sea.
To the 8.E.,
Eskdale, ht.
ft. above Sea,
The Stye, 948
feet above the
Sea,
The Valley,
Seathwaite,
368 ft. above

Stye Head, 1448 feet
To the West,

Lon}
=|
°
ot
2
a

or

—

~I
<2
wm
Oo
nN
“I
bo

May

June
July
August
September
October

Inches. ware . : : 51-69| 41-82

a
wo
on
So ww

_—_
©
— dob
wo Oi

TABLE V.—For the WINTER MONTHS.

THr VALLEY.

Sea Fell Pike.
Lingmell
Great Gabel.
Sprinkling
Tarn,
Stye Head.
Brant Rigg.
Seatollar
Common,
The Valley,
Seathwaite

Wastdale.

Inches. | Inches. | Inches. . | Inches. | Inches. s. | Inches. | Inches. | Inches. | Inches.
Ny

15:59 | 26-90 | 38-86 | 28-63

January : ‘
February 5 i 5 5 i C5 Ps : 7:05 | 15-00 | 17-36 | 15-33
March .. r. . re : . . 5-36 | 7-78 | 9-93 ! 9-36
April > . ; é 2.50 | 5-07 | 6.02 | 6.08
November . P Pe Ps ‘y r. . : 9.15 | 3-84 | 4-89 } 3-74
December . : . 5 . 4-11 |10-10 | 9-49 | 7-99

Imehes. “. . : : 44-46 | 42-16 : 36-76 | 68-69 | 86-55 | 71-13

VOL. XXI. PART I. 28

86

DR MILLER ON THE METEOROLOGY OF

TABLE VI.—TEMPERATURE at SEATHWAITE, BORROWDALB, 368 feet above the Sea-level.

January
February
March

April

May

June

July
August
September
October
November
December

1851.

ABSOLUTE.

Maximum.
Minimum

Mean of Maximum.

Mean of Minimum.

Approximate
Mean Temperature.

"0

eo
<=)
oe |

Mean at 9 A.M.

Absolute
Minimum.

On GRASS.

Radiation.

Maximum.
Minimum,

Prevailing Winds.

NW. var.
NW. SW.
NW.
SW.

S. var.
SW. NW.
NE.
NW.

NW.

Note.—The maximum and minimum thermometers were selected and tested by Mr Gratsuer,
and found to be practically correct; the spirit thermometer, exposed on grass, has been compared
with the maximum thermometer throughout the scale, and its readings are corrected for index

error,

TABLE VII.—TEMPERATURE at WHITEHAVEN, on the West Coast, 90 feet above the Sea-
level, and 17 miles distant in a direct line from the Hamlet of Seathwaite, Borrowdale.

ABSOLUTE.

Maximum.

January
February
March
April
May .
June
July
August
September
October
November
December

Minimum.

Mean of Maximum.
Mean of Minimum.

Approximate
Mean Temperature.

Mean at 9 A.M.

Absolute

Minimum.

On Grass.
On Wool
on Grass.

NAKED THERMOMETERS ON GRASS PLOT.

Mean. —

On Grass.
On Wool
on Grass.

33-66
30-72
32-12
30-53
36-31
43-11
47-42
47-63
39-59
41-27
27-57
32-47

34-99
32-74
34-48
33-79
39-31
45-41
49-25
49-88
43-62
43-87
29-14
34.49

39-24) 36-86

Minimum.

Radiation.

on Grass.

In Sun’s rays.

Maximum,

Radiation.

87

THE ENGLISH LAKE DISTRICT.

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| OG ‘I

88 DR MILLER ON THE METEOROLOGY OF

TABLE [X.— WET Days.

Whitehaven
Bassenthwaite
Loweswater
Lake.
Crummock
Lake.
Wastdale Head
Bowness.
Troutbeck.
Ambleside,
Langdale Head.
Seathwaite.
Stonethwaite.

bo
ew
bo
~~]
bo
wo

January
February
March
April

May

June .
July
August
September
October
November
December

Days. 194 | 187 2 156 | 217 | 202 | 204 | 214 | 221

TABLE X.—Shewing the QUANTITY of RAIN received by the MOUNTAIN GAUGES,
in the year 1852.

XXVI. | XXVITI. XIX.

THE VALLEY. BORROWDALE.

Lingmell, 1778
feet above the
Great Gabel, 2925
feet above the Sea.

Sprinkling Tarn,
1900 feet above Sea.
above the Sea.
above the Sea.
To the West,
Wastdale, 247
ft. above Sea.
To the SE. Esk-
dale, height
unknown.

Seatollar Com-
mon, 1338 feet
above the Sea.
feet above the

Sea.
The Valley,
feet above Sea.

The Pike, 3166
feet above the
Brant Rigg, 924 feet

Stye Head, 1448 feet
Seathwaite, 368

_ thes. s. Inches. Inches. Ss. | Inches.
Jannary (seo) o lr. . Fr. 9. 7 ; : 30-08
February . : : : ' . : . 19-76

Marth S.). . . : 4: 5 : : ; 1-07
Apnll jf 250%. ‘6 . : . : ; 47 95 -67
a Migr ie. fe. ae . . : é : 6 8: : 11-38
Jiinoty. feu . . ; 2. 9. : : ; 12-14
July 4 2. este) aoe . -00|' 8- ; , : 3. 7.13
August §.%. : : ‘ : 9. B : y 11-88
September . : : : : : : : } 4-50
October 1... : . : : : ; é ; 8:37
November . ais te i . 7 : : 17-23
December. : : : : : ; . . 32-38

1852. 81-30 }100-22 134-79 |124-19 : 9- 88-85 |156-59 |167-73
1851. 71-29) 96-29] 81-23 |125-29 |100-16 : . 78-58 |141-42 |169-62

1852.

May

June .
July

| August
September
October

1852.

THE ENGLISH LAKE DISTRICT. 89
TABLE XI.—For the Summer Montus.
0.00 ROR | RRO MRT eR EW. |) OVE | XIV. Santi I FOV Ae SOQ pooh d.05-¢
Sca FELL, 1 3 .3 Ey EB | Tar Vautey. BoRROWDALE.
a D Sm ume Ci yee a

vey oO ae 8 o 9) 5 2 5 | tf ea o

3 ales ao a's aS tis, Se 7 eS a) Bis.
(3) a> ar Qa be oO toto} oO ay oOo o > ae a)
Se ee lee | cee | NS ee | Grae aS | SBS Se slips
C75 Pict) 213 as 3 ae aug oleae are |ne eee
Beles | te | fe | ef | 82 | oe Sa8|/ Sasi es (aes
eeiae | 8") 8) a@ | a |PFele* |des|e2 ("a8
Inches. | Inches. | Inches. | Inches. | Inches. | Inches. Inches. | Inches. | Inches. | Inches. | Inches.
6-63 8:06] 6-48) 11-04] 9-57| 7-69) 8-83 5-78 11-38] 12-04} 11-59
8-20 8-88] 8-00] 12:80] 12-00! 9-57) 8-75 7-34] 12-14} 14-13) 12-33
3:68 5-63 8-00 8:40) 8-25) 7-07| 5-65 3-93 7-13} 9:08) 7-65
8-98} 10-00} 10-58] 13-71] 12-55} 10-00) 9-77} 9-12) 11-88} 14-12 | 12-37
4:00; 4-28 5:07} 4:72] 4-60| 4-34 3-20!) 2-69 4:50| 5-43) 4-64
8-02) 7-12} 6-03} 7-74] 8-00) 7-05) 7-71 6-05 8-37) 9-07) 8-44
41-51] 43-97 | 44-16} 58-41] 54-97 | 45-72] 43-91] 34-91 | 55-40 63-87 | 57-02
: : 2. 83-07 | 68-47

1851. :

TABLE XIJ.—For the WINTER MONTHS.

The Pike.

Great Gabel.

Sprinkling Tarn.|

: January

February .

} March .

|} April

1 November
December

Inches.
16-00
Fy.

Inches,

11-62

1-15
i'r.
27-48

1852.
1851.

56-25
44-89

“VOL. XXI. PART I.

Inches.

Inches.

30:46 :

Stye Head.

Brant Rigg.

Inches.
13-24
10.29

+53
1-06
iin,

THE VALLEY.

BorROWDALE.

To the SE.,

To the West,
Wastdale.
Eskdale.

Common,

Seatollar

Inches.

101-19

Inches.
27-65
20-05

Inches.

17-47

68-69

-98 }
74 |

| 32-83

103-86 | 99-72 |
86-55 | 71-13 |

90 DR MILLER ON THE METEOROLOGY OF

TABLE XIII.—TEMPERATURE at SEATHWAITE, BORROWDALB, 368 feet above the Sea-level.

On GRaAss.

ABSOLUTE.

Radiation.

Approximate
Mean Temperature. |
Absolute
Minimum

Maximum.
Minimum
Prevailing Winds.

Mean of Maximum.
Mean of Minimum. |

Maximum.

- | Mean at 9 A.M.

January

| February .
March .

i April
May
June
July
August
September
October
November
December

2
Or
on

| 1852,
1851.
1850. .
1849.
1848.
1847.
1846.

Or or Or Gr Gr Or
CN ee Sew

“IO rR STOR tr
“IO Gr 00 Gr & 1D

or

TABLE XIV.—TEMPERATURE at WHITEHAVEN, on the West Coast, 90 feet above the
Sea-level, and 17 miles distant in a direct line, bearing NNW. from the Hamlet of

Seathwaite, Borrowdale.

ABSOLUTE. NAKED THERMOMETER ON
Grass PLot.

Radiation.

Approximate
Mean 'emperature.
Mean
Nocturnal
Temperature.

Maximum
Minimum.

Mean at 9 A.M.
Absolute

Raw Wool.
Prevailing Winds.

Mean of Minimum.
Minimum on

Mean of Maximum.

Maximum.

| January SW.

ae . : “ ae :
areh . : . . - asterly.

fApril . . -06 . : Easterly.

| May

June

July .

August

September

October

November
| December

1852.
1851.
1850.
1849.
1848.
1847.
1846.

THE ENGLISH LAKE DISTRICT. 91

TABLE X V.—MINIMUM TEMPERATURE of each MONTH on Sca Fell Pike and the Gabel, and
at Sprinkling Tarn, from July 1851 to December 1852, inclusive.

to a S
& 3 = =
aa A 5 e
1851. - 3 me = 5 CHARACTER OF THE MONTH.
Be 2 n §
tb mM
July x.-s 30 26 26 44 Cold. On the morning of the 4th, ice was seen in some of the |
valleys.
August . 35 30 28 47-5 | Temperature 0°-72 above the average.
September 31 25 23 39 A beautifully fine and dry month. 20th, first snow on the
mountain tops.
October 28 23 22 34 Mild and wet. Some ice left in Sca Fell and Gabel gauges |
on 31st.
November 19 13 11 27 The coldest November on record, at Whitehaven.
December 23 PI 20 26 A mild, but exceedingly dull, damp month. Sun shone out on
11 days only. }
1852.
January 21 18 17 29 An exceedingly wet month. Rain fell on 28 days.
February 18 11 9 26 Very wet till the 17th; afterwards, fine and frosty.
March . 21 15 12 28 A fine and remarkably dry month. Rain fell on 5 days only.

April ‘ 28 23 22 33 A remarkably fine, mild, and dry month. Rain fell on 4 days |
only.
May .. 30 26 24 37 Cold and wet till the 19th; afterwards, fine and clear.

Jame: .. . 34 29 26 44 Rain fell on 25 days. Snow on Skiddaw on the 3d.

Julys >. | 41 37 36 50 The hottest July on record at Whitehaven, Mean of minimum
temperature at Seathwaite, 58°35.

August 5 44 40 37 a0 Warm and wet.

September | 34 28 26 39-5 | Fine and dry.

October 27 22 21 34 Ist, Snow on Skiddaw and Great End, first time this season.
November 21 18 17 25 Mild and wet. Hard frost in the valleys on the 29th and 30th.
December 91 1 19 31 By far the wettest December in the last 20 years, at Whitehaven. |

Rain fell on 30 days.

Means. - 28:0| 23-6| 22-0] 35-8

92

1851.
| Dec.

| 1852.
| Jan.
| March

| April

Means.

Means.

DR MILLER ON THE METEOROLOGY OF

TABLE XVI.—HYGROMETRICAL OBSERVATIONS taken at the MOUNTAIN

WASTDALE Trap. (£4)

On returning.

Brant Kiaa. (B)

46:5

40-3

On leaving.
Wet Dew
Bulb. | Point. —
e h.m.

41-3 | 37-2 | 9-0 a.m.
38-2 | 36-1 8-30 a.m.
36:5 || 3-2 |) 7-10 acm:
40-2 | 36-2] 8-0 a.m.
48-4 | 47-9 | 7-li am.
42-4 | 37- rola Ws roe
51-1 | 48-2 | 7-15 a.m.
49-9 | 46-7 | 5-45 a.m.
52-6 | 50-5 6-15 a.m.
43-3 | 41-4 | 8-0 a.m.
50-1 | 47-6 | 8:15 a.m.
29-5 25-2 | 8-30a.m.
45-4 | 42-2 | 9-0 a.m.
43-7 | 40-6 | 7-42a.m.

SPRINKLING TaRn. (D)

Wet Dew
Bulb. |\Point cae
es ts h. m.

35-2 | 341] 1:0 p.m
30-7 | 30-3 | 0-30 a.m,
29-5 20-5 | 1¥-14 a.m.
36: 33: 0-30 p.m.
45-4 | 43-8 | 0-0 p.m.
36-2 32-1 0-15 p.m.
44-3 | 41-5 |10-30a.m.
49-9 | 46-2 |} 9-lida.m.
46-4 | 43-3 | 10-20a.m.
40:3 | 39-4 |11-0 am.
45-9 45-5 |11-0 a.m.
25- 20:9 | 0-O p.m.
40.3 | 40- 0-0 p.m.
38-8 | 36-6 | 11-30 am.

22:5
38-9

36:5

Dry Wet | Dew Haur
Wet Dew Hon Bulb. Bulb Point i
Bulb. | Point :

“| : h.m. . Z: ie h. m.
39-2 | 35-4 | 6-0 p.m 37-9 | 37-2 | 36-2 | 4-0 p.m.
41-8 | 41- 4:30 p.m. | 36-9 | 35-7 | 33-8 | 3-0 p.m.
35-7 | 30-7 | 4-45 p.m 36-9 | 33-2 | 27-6 | 2-30 p.m.
42. 37: 4:0 p.m 44-8 | 40-3 | 35-2 | 3-0 p.m
46-9 | 44- 4:0 pm. | 41- 40-7 | 40-3 | 2-30 p.m
42- 35-4 | 7-45 p.m 46-3 | 41-3 | 35-8 | 3-0 p.m
54-6 | 53-1 | 7-0 p.m 55-1 | 52-1 | 50- 2-30 p.m
58-7 | 54-7 | 3-0 p.m 64-9 | 58-7 | 54-9 | 0-0 p.m.
44-8 | 40-4) 5-0 pm 54-1 | 51-6 | 49-2 | 2-0 p.m
ae t wat 45- 44-3 | 43-5 | 1-30p.m
55-7 | 55: 4:30 p.m 52-6 | 51-7 | 50-8 | 3-0 p.m.
30-2 | 24-4 | 4-0 p.m 33-3 | 31-2 | 27-7 | 2-30 p.m,
46-4 | 45-1 | 3-30p.m. | 44:5 | 44-3] 43- 2:0 p.m
44-8 | 41-3 | 4-50p.m. | 45-8 | 43-2 | 40-6 | 2-25 p.m.
GREAT GABEL. (BE) LINGMELL. (F)

Wet | Dew Hour Dr. Wet Dew Honr
Bulb. | Point Bulb. | Bulb. | Point.

A iu h, m. . re & h.m,

30:5 | 29-7 | 3-0 p.m. | 36-9 | 36-2 | 35-1 |10-0 a.m.
31-2 | 29-8 | 1-30 p.m. te oe tee :
28:5 | 27-8) 2-0 pm. | 323 31-7 | 30-7 |10-0 am.
28-7 | 27-5 | 1-30p.m. | 31- 29- 23-7 | 9:0 am.
30:7 | 26-6 | 2-10p.m. | 41: 38-7 | 35-9 |10-0 a.m.
40-8 | 40-6 | 2:0 pm. | 48-3 47:4) 46-4 | 9-0 a.m.
34-2 | 31-6 | 2-0 p.m. | 42-5 | 39-2 | 35-2 | 9-15 am.
42-3 | 41-4 | 1:45pm. |] 46:3 45:9 | 44-9 | 9-15 a.m.
48-4 | 47-4 |10-50a.m. | 55-6 51-5 | 48- 7-15 a.m
43-3 | 43-1] 0-45 pm.| 49-3 47-9] 464] 8-0 am
38-9 | 38-7 | 0-30p.m. | 41:5 40-8 | 40-2 | 8-45 a.m.
44-3 | 44-1} 2.0 pm. | 46:3 45-4 | 44-4 | 9:45 a.m
21- 9-8 | 1-30 p.m. | 25-8 | 25- 21- |10-0 am
38-3 | 37-3 | 1-30p.m. |] 41- 40:3 | 39-4 | 10-0 a.m. |
35:8 | 34:0 | 1:37 p.m. | 41-4 | 39-9 | 37-8 | 9-15 a.m.

THE ENGLISH LAKE DISTRICT.

93

STATIONS adjacent to the Vale of Wastdale, in the Year 1852.

Styre Heap. (C)

Dry

| Bulb.

49.7

|e EER

Wet
Bulb.

36-2

40-9

Dew
Point.

41-4

38:5

11-20 a.m.
11-30 a.m.
1-0 p.m.
0-30 p.m.
0-30 p.m.

0-16 p.m.

ee

Dry
Bulb.

30-6
29-6

34-6

Sca FELL PIKE. (G)

Wet
Bulb.

33:8

Dew
Point.

31-5 | 10-30 a.m.

Hour.

h. m.
11-30 a.m.
11:0 a.m.

11:0 a.m.
10-20 a.m.
11-20 a.m.
10-20 a.m.
10:30 a.m.
10-30 a.m.

8-15 a.m.

9-15 a.m.
10-0 a.m.
11-0 a.m.
11:0 a.m.

11-0 a.m.

VOL. XXI. PART I.

Dec. 30
» ol
1852.

Jan, 31

March 1.

more ol.

April 30.

May 31.

Jaly< 1.

August 2.

resi

30.

dl.

STATE OF THE WEATHER AT THE DIFFERENT STATIONS.

. Damp mist at all the stations.
. The same.

. A, 835 a.m., fine morning; 4ih pm., rain; B, heavy rain; C, |

heavy rain, but below the mist. Misty, with snow or rain, at |

all the other stations.
A and B, fine and clear; C and D, large flakes of snow falling,

no mist; E, misty, occasional gleams ; F, clear and frosty; j

G, hard frost, some snow falling.

Overcast, with an absence of mist at all the stations. Faint
eleams at F, and bright sunshine at G.

Dense mist, with small misty rain, at most of the stations. Fair
at C, F, G, and at A, on returning.

Overcast, no mist or sunhine.

A, at 7" 15™, overcast, fair; at 7 p.i, fair; mist low down on the
mountains. B, gleams. C and D, overcast, without mist. H,
misty, with smal] misty rain. F, just entering the mist. G,
very dense mist, with small misty rain.

A, cloudy. B, hot sunshine.
shine. E, misty. F and G, fair and clear.

A, at 65 15™, dark morning, with some rain; at 5 p.m., fair and
clear. B, fair, a heavy shower just ceased. C and D, fair,
and clear of mist. E, very wet and misty. F, misty. G, dense
mist.

. A, dark morning, with appearance of rain, B, C, and D, very wet, |

but below the mist. E, very wet and misty. F, rain began
close to the under surface of the mist. G, very wet and misty.

. A, on leaving, overcast, but fair; on returning, very wet. Band

C, very wet, but below the mist; dense mist with small rain
at all the other stations.
Hard frost, overcast, a transient gleam; no mist at any of the
stations.
A, on leaving, fair but misty ; heavy rain on returning. B, wet,
but now below the mist. C, misty, but nearly fair ;—dense
mist with rain at all the other stations. A complete hurri-

cane on Sca Fell Pike. Gauges all free from ice.

Note.—The readings of the Dry and Wet Bulb Thermometers have all
been reduced to a standard instrument, selected by Mr GLAISHER of the |
Royal Observatory.

C and D, neither mist nor sun- |

94 DR MILLER ON THE METEOROLOGY OF

TABLE XVII.—DerpvucTIONs relative to the Humipity of the ATMOSPHERE at the
MountTAIN STATIONS, in the year 1852.

WEIGHT OF
VAPOUR.

STATION.

Wet Bulb.
Dew Point.
In a cubic foot
of Air
| Required for
Saturationof a
cubicft. of Air.
Degree of Humidity,
(complete Saturation
1-000.)

h. m.

Wastdale Head, 7-42 a.m., 247 above the Sea,
Do. do. 4-50 p.m.,

Brant Rigg, :

Stye Head,

Lingmell,

Sprinkling Tarn,

Great Gabel,

Sca Fell Pike,

In addition to the above systematic readings, I find the following casual observations dispersed
through the Registers :—

September 5, 1845.—The thermometer on the summit of Skiddaw, at noon, stood at 41°; sky
overcast, sun gleaming out at intervals. Temperature of a strong spring, about 2 miles from the
summit, also 41°. Air at foot of mountain, 3" 30™ p.m., 58°.

May 6, 1847.—Temperature of air at foot of Sca Fell, at 108 40™ a.m., 52°; on the summit of
the Pike, at 1 p.m., 37°, and intensely cold. Extensive drifts of snow on the east side of the moun-
tain. Temperature of a spring near Sprinkling Tarn, 37°. Between 4" and 5® 30™, p.m., whilst
passing over Stye Head in the direction of Borrowdale, there occurred one of the most dreadful storms
of thunder and lightning which it has been my lot to witness. The electric discharges were frequent
and extremely dazzling, and many of them followed, almost instantaneously, by deafening peals
of thunder reverberating from hill to hill. A large quantity of hail fell, (unaccompanied by rain,)
quite sufficient to give me a thorough drenching. The storm was confined to the mountains, and the
hail did not reach the valleys. I made two attempts to ascend the Gabel, and on both occasions was
obliged to retreat before the fury of the elements.

September 9, 1847.—Ascended Snowdon in Wales, and found the temperature at the Farm-
House on the Beddgelert side, to be 56°-7; at the summit, 46°8, a difference of only 9°-9 in 3571
feet, or a descent of 1° in every 357 feet of elevation. We ascended Snowdon through an exceed-
ingly dense mist, which enveloped the mountain nearly to its base. The fine white vesicles composing
the cloud settled upon our garments, and long before arriving at the summit, they appeared as if
covered with minute particles of snow. I am inclined to think that the latent heat evolved by the
vapour during its conversion into mist (Cirrostratus) tended to equalize the temperature between the
top and bottom of the mountain, and that a much greater difference would be found in a clear, or
even a moderately clear atmosphere.

THE ENGLISH LAKE DISTRICT. 95

TABLE XVIII.— HYGROMETRICAL OBSERVATIONS, taken April 22, 1848.

Degree of
Humidity,
(complete
Saturation
1-000).

Wet Dew

STATE OF THE WEATHER.
SOEUR: . | Bulb. | Point.

h.m

Wastdale Head, . | 11-15 a.m. fs “ 44.4 0-708 | Sky overcast, strong breeze.

Brant Rigg, . .| 145 Pu. 41-8 -864 | Mist extending below Sprinkling|
Tarn.

Stye Head, . . .| 2-45 P.M. 39- 858

Sprinkling Tarn, .| 4:0 P.M. . : . -928 | Bnveloped in dense mist.

Great Gabel, . 6:0 P.M. . -926 | A gale with heavy rain, par-
tially frozen.

April 24, 1848.—Seatollar Common, Temperature at Seathwaite, at 11 a.m., 46°; Wet Bulb,
41°; Dew Point, 35°5; Humidity, 0-694; at summit of Common, air temperature, 43°; Wet Bulb,
39°; Dew Point, 34°2; and Humidity, 0-736.

TABLE XIX.—HYGROMETRICAL OBSERVATIONS taken on ScA FELL, April 21, and
July 17, 1848.

Degree of
D Humidity,
STATION. y (complete STATE OF THE WEATHER.
Saturation
1-000).

h. m. a i
April 21, | Wastdale Head, | 11-40 a.m. . 0-708 | Astrong breeze prevailed in the |
valley throughout the afternoon.

Top of the Pike, 4-30 p.m. i Calm, overcast, followed by rain. |

The clouds (evidently electric) }
‘are generally below the summit.
Foot of Mountain, 11-45 a.m. . . Light breeze, overcast.

Top of Lingmell, 2-10 P.M. L7- : Fresh breeze, evercast.

Spring on do., in

Top of the Pike, 3-30 p.m. | 44-2) 44-2 : Fresh breeze; enveloped in mist,

air saturated.

July 16, 1848.—Stye Head. Temperature near Valley, 68°; Wet Bulb, 61°; Dew Point, 56°8 ;'
Humidity, 0-691; 5 p.m., temperature on Stye Head, 60°; Wet Bulb, 56°°5; Dew Point, 54°; Hu-
midity, 0-820,

96 DR MILLER ON THE METEOROLOGY OF

TABLE XX.—HYGROMETRICAL OBSERVATIONS, taken July 1st and 2d, 1851.

Degree of
Humidity,
STATION. (complete STATE OF THE WEATHER.
Saturation

1-000).

h.m. Q HA .
Wastdale Head, 7.0 P.M. f ‘ . : Very fine and sultry, Cumulus;
5 to 7 P.M., heavy rain with
Stye Heady, 6. 2. 9-15 P.M. ° . : much thunder and lightning
at Wastdale Head; afterwards,
fair but cloudy.
Stye Head Tarn, 9-30 P.M. : " ; -703* | Thermometer at Seathwaite rose
to 80°.
Seathwaite, . . 1:30 p.m. -9| 57: ‘669 | Very fine and sultry, mostly
clear, light breeze ; evening,
Seatollar Gauge, | 3-0 p.m. . 7 | -664 | cloudy on mountain tops.

Top of Seatollar, | 3-30 p.w.| 62-9) 56-7) 52. 703

* The Humidity at Stye Head Tarn is apparently too low; it is probable the Dry Bulb Thermometer was incor-
rectly read off, in the dusk of the evening.

TABLE XXI.—HYGROMETRICAL OBSERVATIONS, taken December 15th, 16th, and 17th, 1850.

Degree of
Humidit
: Dry | Wet | Dew | y>
1850. STATION. Hour. Bulb | Bulb. | Point geo: STATE OF THE WEATHER.
aturation
1-000).

SS

h. m.
Dec. 15, Nair ets rosey ot 2.45 pu. | 42 | 38-7| 34-7] 0-779
ote

43 Gauge on do., .| 3-30p.m. | 37 | 34-7] 31-2 -816 | 1888 feet above Sea.

» 16, | Seathwaite, : . |11-30 a.m. | 43 | 39-2] 34-6] 0-748
- Gauge on “Stye,”| 0-Op.m. | 40 | 37-2} 33-8 -806 | 948 feet above Soa.

- Stye Head Tarn, | 1-30P.m. | 38 | 36-7| 34-7 -894 | 1290 feet above Sea,

» 17, | Gaugeon Lingmell| 11-30 a.m. | 32-8| 32-2) 31-2] 0-943 | Heavy rain.

5 Wastdale Head, 10r.u. | 40 | 39 | 37-8 ‘926 | Heavy rain throughout the day;
air completely saturated at
noon; dry and wet, both 40°.

an Do. do.,. | 4:30pm. | 40 | 38-2) 36 -871 | Humidity rapidly decreasing.
35 Brant Rigg,. 5 | 5:-37p.m. | 37 | 35-2) 32.5 -854 | Fine starlight evening.
45 Gauge, Stye Head, 6-40 p.ar. | 35-8} 34-2] 31-8} -868 | The same.

SS SSS SS

97

THE ENGLISH LAKE DISTRICT.

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*saouy | "soqouy ‘soyouy | “Somouy |*svyouy | ‘soyouy | *soyouy
A mM
g Sale
nee oe) lleva: Maw e
Bier || eee S ce | 2 | Se Pee
3 | &2 s | w | 32| Be | 2a
as | eel ae © Be eS ie acgeres
jana? eS airs = et OO [o) e oo
Oho os © 9 @ © ae os
ms | 28 | ne Cee Bo ee alter
vee o 8B 3° 2 te |e ee eS
S| ee eas Se | So ieea | os
eae Bao faced 1ST BRS g
s | 2h ® © eE| os *
ee ifee | 4 BL | By re
3 $ 3s | ow g,
g "NO AVAH SALIH AV
"Ix >. "Soh “IIA “AT “III aig

10(0}9Q

*SUBOTAL
“PP8I
“CPST
“OPST
“LEST
“ST8I
“6PSI
‘CSSsI
“IS81
“ES8I1
“eS8I

“00d
“AON

“dag

qsneny |
Ayn |
oune |
Avy |
qady |

YOAV
“qo

“Uv |

“S81

‘ON

VOL. XXI. PART I.

98

1853.

January
February
March
April

May

June
July
August
September
October
November

December

1853.
1852,
1851.
1850.
1849.
1848.
1847.
1846,
1845.

Mean }

| Number.

Whitehaven.

195

DR MILLER ON THE METEOROLOGY OF

The Flosh.

J oe
i |
19 | 22 ||
12 | 15
12 | 14
16 16
6 7
11 15
21 19
ior i) 022
14 18
26 | 21
14 17
11 11

172 | 189
204 | 201
211 | 202
209 | 198
205 | 191
229 | 217
204 | 190
213 | 198
195 | 195
204 | 198

TABLE X XIIJ.—WetT Days,

q
iS
22 22
13 5
17 13
20 | AF
4 5
16 11
23 21
14 9
19 12
25 18
18 13
12 4
203 150
| 212 | 194
| 232 173
248 168
236 | 164
243 190
226 174
234 | 194
211 178
227 | 176

Selside.

Troutbeck.

Ambleside.

Seathwaite.

Stonethwaite.

bo
i

191
207

| 206

199
183
224
195

201

THE ENGLISH LAKE DISTRICT. 99°

TABLE XXIV.—Shewing the QUANTITY of RAIN received by the MOUNTAIN GAUGES,
in the Year 1853. :

XXIII. XXVI. | XXVII.

XXIV. XXY.

Sca FELL. -| w g 3 $ m THE VALLEY. BoRROWDALE,.
Ae ee blac

See ieee eb leta i am tale | a 8s laee | Ba
Bo [fe [ee | Pe | 28 | os |882|Gee one as | Boe

1853. oF wed ae mF 0 Soe on HOG1 So | as
23 |22 | 88.| 88 | 22 | #2 [ese\Ses|sceies | see
ze |3¢ * aos & Fag a He
Inches. | Inches. | Inches. | Inches. | Inches. | Inches. | Inches. | Inches. | Inches. | Inches.'| Inches.
January r. Fr. r r. | 13-71| 10-43 | 23-02 | 24-20) 23-12
February Fr Previn Br Pr. |, Brest 3-61) 2-75; Fr.|. Fr-| 3-84

Era |) Er
March) os) 64): Fr. | 17-70 ee ee eos 18:00} 3:57| 3-18} 6-54] 8-37] 4-59
April . : ee

May Goitet % 7-75 -10| 6-46 -30 -34 73 -66 -68 -46 1.19 -89
June tA) oe 3-44) 3-71 4:00| 5-35] 4:59} 3-52] 3-92] 2-94! 5.06] 4.98] 4-07
July cae: 15:88 | 15-70} 16-00] 21-10} 20-30) 14:71] 15-97| 8-93) 18-73] 23-05 | 19-67
‘Aueust ... ; 7:20} 8-00} 7-70] 10-35 /) 8-70} 8-00) 7-09} 10-58} 11-77| 10-47
September . . 5:19) 6:00] 6-46} 8-47 6-42] 8-07] 5-62/ 10-21} 11-55} 10-42
October...» 6-61] 9-25) 7-11) 14-:00|}37-69 |; 7-61 9-11 8-36] 12-76} 14-60 | 13-25
November... . 3-20| 5-75} 3-40) 6-11 hs 6-68} 7-56! 5-01} 10-14] 10-05} 9-47
December . . +85 “50 41 47 1-03 1-25 1-15 1-22) 1-29 1-23
1853. 56-17 | 71-06] 59-72) 94-59| 92-65) 73-40) 83-39] 63-07 |111-45 |124-91 |113-69
1852. 81-30 |100-22)| 85-75 |134-79 |124-19| 98-24 109-58 | 88-85 |156-59 |167-73 |156-74
1851. 71-29 | 96-29} 81-23 }125-29 |100-16| 89-51 | 97-94] 78-58 |141-42 |169-62 |139-60
71850. 80-31 | 92-50} 87-28 |127-80 |115-53 | 91-10 |101-50| 76-01 |138-84 |174-33 |136-62
+1849. 83-21 | 91-90} 84-92 |121-10 |105-15 | 87-30 114-48 | 76-90 |108-97 128-03
§1848. 94-73 91-32 |148-59 |138-72 |109-19 |127-47 | 95-71 |139-48 177-55
eas} 128-15 13698 |207-91 |185-74 170-55 180-23 223.64

* The Stye Gauge was injured in August, and it was not subsequently adjusted. The depth of rain, from
August to December inclusive, is calculated by differentiation with Sprinkling Tarn in the corresponding months
of 1852.
¢ For 11 months. ft and § For 13 months each.
|| For 21 months, from March 1846 to November 1847 inclusive.

January 31, The Wastdale Mountain Gauges were not read off, on account of the-illness of
the Registrar.

February 28. The Mountain Gauges were all frozen up, and covered with snow.

April 2. The Gabel and Sprinkling Tarn Gauges were partially frozen. Sca Fell Pike could
not be found, on account of the dense mist.

May 2. Some ice left in Sca Fell and Gabel Gauges.

November 30, A little ice left in Sca Fell receiver.

December 31, The Mountain Gauges (all frozen) were brought down to the valley, and the
experiments closed.

100

| | as |

1853.

May

June

July
August
September
October

1853.
1852.
1851.
1850.
1849.
1848.
1847.
1846.

DR MILLER ON THE METEOROLOGY OF

TABLE XX V.—For the SUMMER MONTHS.

XXI xxi?
Sca FELL
£3 |§3
e2 | > 3
Sie = 20
oo | Ea
mS ope)
a4 |3¢
Inches, | Inches
-40 -10
3-44) 3-71
15-88| 15-70
7-20| 8-00
5-19} 6-00
6-61 9-25
38-72| 42-76
41-51 | 43-97
45 96| 51-40
44-37 | 45-82
46-68 | 45-90
‘49-46 tee
43-98
45-45

Great Gabel, 2925
feet above the Sea.

Inches.
-46
4-00
16-00
7-70
6-46
7-11

41-73
44-16
45:77 |
45-29
46-47
46-81
43-30

Sprinkling Tarn,
1900 feet above Sea.

Inches.

5-35
21-10

59-57
58-41

63-97
58-53
70-95
62-30

52-39

70-83

10-35 |
8-47 |
14-00 |

70-61 |

XXIII. XXIV. | cy |X iv.

Stye Head, 1448 feet
above the Sea.

| Brant Rigg, 924 feet
above the Sea.

|

Inches.
+34 73
3-52
14-71
{ 8-70

| 56-77
| 54-97
55-70
59-63
54-29 |
60-35 |
56-98
58-42

|
| XIII,
|
!

THE VALLEY.

To the West,
Wastdale, 247
feet above Sea.

To the SE., Esk-
dale, height
unknown.

Inches.
-68
2:94

on
=
a

| 55-40

XXVI.

XXVIII. XIX.

BORROWDALE.

Sea.
The Valley,

mon, 1338 feet
Seathwaite, 368

Seatollar Com-
above the Sea.
The Stye, 948
feet above the
feet above Sea.

Inches.
-89
4-07
19-67
10-47
10-42
13-25

Inches. | Inches.
-46 1-19
5-06} 4-98
18-73 | 23-05
10-58) 11-77
10-21} 11-55
12-76| 14-60

58-77
57-02
68-47
60-18
55-73
68-96
62-95

57-80 | 67-14
63-87
| 83-07
77:37

57:97 | +e

56-80; ---

72-23

* On the 3lst August 1839, the Seatollar Gauge was removed 90 yards to the South Westward, and about 5 feet lower
down the Mountain.

1853.

TABLE XX VI.—For the WINTER MONTHS.

The Pike.

January
February
March
Aprils. |.
November
December

1853.
1852.
1851.
1850.
1849.
1848.

“{ 1847.

Inches.

Inches.
Tahig
ir:

17-70
4-30
5-75

“590

28-30
56:25
44-89
46-68
46:00

Great Gabel.

Inches.

Sprinkling Tarn.

* For Nine Months only.

Stye Head.
Brant Rigg.

THE VALLEY.

To the W.,
Wastdale,

Inches. | Inches.

ir: rs

6:32
f 6-15 ||

35:88
69-22
44-46
55:90
50-86
78-37

70-34

42.72
For 7

Months

29-45
53-94
36-76
40-65
41-92
58-02

BORROWDALE.

Seatollar
Common,
On the Stye.
The Valley,
Seathwaite.

Inches. | Inches.
24-20} 23-12
3-84

53-65
101-19
68-69
76-22
58-93] ++
81-51} +

57-77 | 54-92
103-86 | 99-72

Months

40-29 }
For 7

67-31

THE ENGLISH LAKE DISTRICT.

101

TABLE XX VII.—MontTHLY EVAPORATION at WHITEHAVEN, CUMBERLAND, in each of
the Twelve Years ending with 1853.

Months.

January
February
March
April

May

une: .
July
August .
September .
October
November

December

Evaporation.

Rain at

Whitehaven \

Rain at
Seathwaite.

1842.*

Inches.

785
1-178
1-620
1-718
3:045
4-690
3-125
3-305
3-745
1-940
1-030

-800

26-981

46-206

1843-t

1844.

Inches,

0-940
1-190
1-835
2-610
6-280
3-820
4-495
2-520
3-405
2-270
1-554

-800

31-719

36-723

1845.

Inches.

1-015

Inches.

0-935

‘905 | 1-335

1-862} 2-085

3-400 | 2-575

3-645 | 4:375

3-760 | 6-645

5-455 | 3-450

3-250 | 3-875

3:225 | 2-980

2-360} 1-780

1-760 | 1-360

1-875 | 1-025

32-432 32-500

49.207 |49-134

151-87 |143-51

1846.+

1847.

Inches.

0-860

+843
1-821
2-181
2-950
4-506
4-726
3-751
2-793
1-688
1-107

1-005

28-231

42-921

129-24

1848.

Inches.

0-743

-792
1-397
2.728
4-580

3-749

3-935
3-686
2-896
1-549
1-129

1-019

28-203

47-342

160-89

1849.| 1850.

Inches.

0-693

Inches.
0-909
1-024} -823
1-558) 1-690
2-620 | 2-295
3°886 | 3-505
5-076 | 4-290
4-156] 4.278

2:657 | 3-381

3-337 | 2-664
1-723 1-558
-960| 1-181

‘793| -991

28-699

27-349

38-999 |40-473

125-47 |143-96

——__._

25-340

43-120

139-60

1852.

Inches.

1-284
1-194
2-197
3-940
3-570
3-172
4-672
3-551
3-041
1-510
1-143

1-074

30-348

50-030

156-74

113-690

* The Evaporation for 1842 is computed from the evaporation force, in proportion to the respective values of
the estimated and measured evaporation in the corresponding months of the years 1843 and 1844. The result, cal-
culated for the mean of the whole period (1843-1846) during which the evaporating force and the spontaneous eva-
poration were registered daily together, is 39°870 inches :—

Grains.

Thus, if 19:99

Inches.

30°908

Grains.

25°8

Inches.

39°87

¢ The evaporation in 1843 is somewhat too small in amount, from the gauge not being sufficiently exposed to
wind and sun during the first half of the year.

+ Till the close of 1846, the dish was placed on a stool 8 inches above the ground ; since that period, it has been
placed on a stand 4 feet 4 inches in height, and just large enough to hold it.

VOL. XXI. PART I.

yea

102

DR MILLER ON THE METEOROLOGY OF

TABLE XXVIII.—TEMPERATURE at WHITEHAVEN, and at SEATHWAITE, BORROWDALE,
in the year 1853.

1853.

January
February
March
April
May

June

July
August
September
October
November .

December .

1853,

Average of
8 Years,
1846-1852.

SEATHWAITE, BORROWDALE. WHITEHAVEN.

ABSOLUTE. 5 g 2 p 3 4 ABSOLUTE. gE g 3 2 4

a £ ams 4 = EI & Bil fbi

fe gave BD leet kes ealece e ge) aloe led | (oe eae
s | 5 a a fe |< 2 Behe hea, SE Sea = es| @

a es S | BABS) 8 re fo) Beles 3 | 2oeee

— - a) A 4 ot ° o i= =
| & 3 s | Be | & 5 en ae a | be] §
=| 4 IRB i ss lear he 2/5 2 | 4 | 7
51 | 27° | 42:05| 36-79| 39-42| 39.22} SW. |51 |27-5| 44:30] 37-91| 41:10| SW.
41 20 35-71 | 26-60) 31-15] 31-42 NE. 43 |20 | 38-09] 30-50| 34.29] NE.
50-5} 22 41-64] 32-48] 37-06| 36-17 SE. 53-5| 22-5) 44.55] 34-10] 39-32] E.
53-5] 33 48-03 | 39-81 | 43-02} 42-65 NW. 57 |33-5| 51-20] 40-93| 46-06] W.
69-5| 36 58-92} 45-14) 52-03] 50-08 SE. 75 |35 | 61-03] 44-04] 52-53] NE.
fo WAL 63-21] 52-46) 57-83] 57-41 W. 75:5|44 | 64-33] 50-96| 57-64) SW.
66 | 50 59-40 | 53-59] 56-49] 56.43 SW. 70 | 50-5) 63-82) 54-01} 58-91) SW.
68:5| 47-5 | 60-51| 52-87] 56-69| 56-12 NW. 70-5| 46-5] 64-10 | 53-74] 58-92) W.
64 42-5 | 56-53| 49-10) 52-81] 51-76 NW. 68 |42 | 60-82) 50-51] 55-66] SW.
58 | 35 51-95 | 45-80 | 48-87 | 48-25] SW. var. | 59-5} 37-5) 55-69] 47-73} 51-71| SW.
Bley |} sill 46:05 | 39-85 | 42-95 | 42-60 SW. 56-5} 31 | 47-70] 41-65} 44-67) SW.
51 19 38-05 | 31.22] 34-63] 33-93| NE. & SH.|52 |23 | 39-72) 33-37] 36-54) KH.
58-4 34-2 | 50-17| 42-14] 46-15] 45-50| SW. var. | 60-9) 34-4) 52-94] 43-28] 48-11} SW.
61-2) 32-3 | 51-97] 42-69| 47-32} 46-73 SW. 62-8] 34-3) 54-10] 44-26) 49-18} SW.

THE ENGLISH LAKE DISTRICT. 103

TABLE XXIX.—MINIMUM TEMPERATURE of each MonTH on Sca Fell Pike and the Gabel,
and at Sprinkling Tarn, in the Year 1853.

1853.

January .| 21
February .| 20
March ".~ . |: 23
mpl. | 85

May ..- |. 26

dane = /- . |" 42
Wily. 3 | 41
August ... |. 39

September 32
October .| 30

November 27

December 16
1853. 28-4
1852. 28:6

Great Gabel.

13

22-9

23-6

Sca Fell.

21-5

22:0

Seathwaite.

47-5

34-2

CHARACTER OF THE MONTH.

A mild,‘wet month, Minima taken February 16.
A dry, frosty month; frequent snow showers.
A fine, dry, cold month; frequent snow showers.

A fine seasonable month.

A very fine and exceedingly dry month. On the 9th, the
valleys were covered with snow.

A fine, but rather cold month.

Cold and damp.

Fine and dry.

Do. do.

Mild and wet. On the 2d, Great End was covered with
snow. ‘

A mild month. Snow on Fells.

A very dry, frosty month. Frequent snow showers in the
valleys.

February.—At the middle and end of this month, the depth of snow covering the Sprinkling
Tarn thermometer was estimated at 2 feet.

18 inches.

On Sca Fell and Gabel, the depth was probably about

March.—The high reading of the thermometer at Sprinkling Tarn in the first’ three months is
owing to the greater depth of snow covering the instrument. The thermometer was found to be in

good working order.

December 31.—The thermometer box at Sprinkling Tarn was under 18 inches, and those on
Gabel and Sca Fell under about 15 inches of snow.

104

DR MILLER ON THE METEOROLOGY OF

TABLE XXX.—MONTHLY HYGROMETRICAL OBSERVATIONS taken at the MOUNTAIN

DATE. WASTDALE HEAD. (A) Brant Riee. (B)
On leaving. On returning.
yan Dry Wet | Dew Hone Dry Wet | Dew Hoar, Bulb, Bulb. Point. Hope,
Bulb. | Bulb. | Point. Bulb. | Bulb. | Point.
“a 5 5 ° “ham. : . iP o | bem. TIE S o | hm.
Feb. 16.| 29- 26-5 | 16-5 | 8-15 a.m 33-8 | 29-6 | 22-7 | 3-30p.m. | 26-6 | 246] 14:5 |10.0 am.
‘, 28.| 28-6 | 27- 20-4 | 8-45 a.m 35-8 | 33-2 | 29-3 | 5-45 pm. | 33-8 | 31-5 | 27-8 | 3.15 p-m.
April 2.| 42-5 | 40-3 | 37-6 | 8-0 am 47-3 44.3 41: 4-45 p.m. | 38-9 | 38-2 | 37-1 | 9.45 am.
May 1.| 59-7 | 50-5 | 44- 1-30 p.m 58-2 | 49-4 | 43-3 | 7:30pm. | 54-6 | 47-4 | 41-6] 3.15 p-m.
| Pa 31.| 47-3 | 443 | 41- 6:0 am 66-9 | 57-7 | 52-1 | 3-0 p.m. | 65-9 | 56-7 | 51-1 | 1.0 p-m.
June 30.| 58-7 | 53-6 | 50- 4:0 p.m 54:6 | 40-4 | 45-2 | 9-45p.m. | 49-3 | 46-4 | 43-3 | 9-0 p.m.
August 2.| 58-7 | 55-6 | 53-4 | 8-45 a.m 60-7 | 55-6 | 52- 6:0 p.m. | 57-7 | 53-6 | 50-7 | 4.0 p-m.
» 91.| 55-1 | 52-1 | 49-9 | 3-30 p.m 50:8 | 48-4 | 46- 8-15 p.m. | 49-3 | 48-4 | 47-4 | 7-40 p.m.
Sept. 30.} 48-8 | 45-8 | 42-5 | 8-0 a.m 51-6 | 46-9 | 42-2 | 4-0 p.m. | 48:3 | 45-4 | 42-2 | 2.30p.m.
Oct. 31.| 54:3 49:4 | 45- 9-45 a.m 55-6 | 50-4 | 46-8 | 5-30p.m. | 51-4 | 47-4 | 43-4 | 4.0 p.m.
Noy. 30.) 45- 43-3 | 41-4 | 8-30 a.m 43-5 | 41-3 | 38-6 | 4:0 p.m. | 41 39-2 | 37- 2-45 p.m.
Dec 31.| 30-6 27-5 | 18: 9-30 a.m 27-5 | 25:5 | 15-8 | 445 p.m. | 28- 25-1 | 11-6 |10-0 a.m.
1853. 46:5 | 43-0 | 38-3 |10-2 a.m 48-8 | 44-3 | 39-6 | 5-34p.m. | 45-4 | 42-0 | 37-3 | 2-36 Ae
1852. 46:5 | 43-7 | 40-6 | 7-42 a.m 48-1 | 44-8 | 41-3 | 4-50p.m. | 45-8 | 43-2 | 40-6 | 2-25 p.m.
SPRINKLING TARN. (D) GREAT GABEL. (B) LINGMELL. (F)
1853.

Bulb. Buh, Point Hous Bulk Bulb. pa Poe Ball. Bulb. Point ior
ae eee ee ee ee a ae
Feb. 16.| 23-5 | 22-5 | 15-9 11-0 p.m. | 19-3 | 19-5 | 19-3 | 1-0 p.m 24-6 | 24:5 | 23-8 | 10-15 a.m.

Rs 28.| 25-6 | 25:2 | 24.2 | 0-45 p.m. | 23:5 | 23-5 | 23-5 | 2-30 p.m 26- 25- 19-9 | 10-15 a.m.
April 2.| 36:9 | 36-2 | 35-1 | 0-15 p-m. | 30-3 | 30-2 | 29-2 | 11-15 a.m 37:9 | 37-2 | 35-9 | 3-40 p.m.
May 1 50-9 | 44-5 | 381] 4:0 p.m. | 46: 40-3 | 34- 5.30 p.m 52- 46- 40: 8-0 a.m.

5 31.| 54:6 | 49-4 | 45-2 |10-45 p.m. | 56-1 | 50-4 | 46-5 | 0-15 p.m 54:6 | 49-4 | 45-2 | 8-15 a.m.
June 30.| 45: 43-3 | 41-4] 7-0 pm. | 50-5 | 39-7 | 38-7 | 8-20 p.m 47- 45- 42-8 | 5-20 p.m.
August 2.| 52-6 | 49-4 | 46-2 | 1-0 p.m. | 50-3 | 48-4 | 46-5 | 3-0 p.m 57-7 | 54-6 | 52-4 /10-0 a.m.

a 31.| 46-3 | 45-4 | 44-4 | 6-45 p.m. | 42- 39-8 | 37-1 | 6-30 p.m 48-3 | 46-4 | 44-3 | 4-45 p.m.
Sept. 30.| 41- 39-2 | 36-2 |11-30 a.m. | 38-6 | 37-2 | 35-1 | 1.30 p.m 41- 39-7 | 35-1 | 9-30 a.m.
Oct. 31.| 43: 41-8 | 40-3 | 2-0 p.m. | 25- 43-8 | 39-1 | 3.15 p.m 47-3} 44.3} 41- |11.45 am.
Nov. 30.| 36-9 | 35-7 | 33-8 | 0:30pm. |} 33-3 | 33-2 | 32-9 | 2-1 p.m 38: 37-2 | 36- | 10-15 a.m.
Dec. 31.} 23. 21-4 9-4 | 1:0 p.m. | 17: 16-1 9:3} 3-0 p.m. | 20-5 | 19-6 | 12-8 | 10-15 a.m.
1853. 39-9 | 37-8 | 34-2] 1-42p.m.| 36-8 | 35-2 | 32-6 | 3-0 p.m. | 41:2 | 39-1 | 35-8 | 11-31 am.
1852. 40-3 | 38-8 | 36-6 |11-30a.m. | 36-5 | 35-8 | 34-0 | 1-37 p.m. | 41-4 | 39-9 | 37-8 | 9-15 a.m.

THE ENGLISH LAKE DISTRICT. 105

STATIONS adjacent to the Vale of Wastdale, for the Year 1853.

StyvE HEAD. ()

STATE OF THE WEATHER AT THE DIFFERENT STATIONS.
Dry Wet | Dew

Bulb. | Bulb. | Point. Hour
\S eee
25-8 | 24-5 | 17-8 | 11.30 a.m. 1853.

31-8 | 30. | 261 | 1-20 p.m. Feb. 16. Dense mist on Sca Fell ; no mist or sun at any of the other sta-
tions, except at Wastdale Head on returning, when the sun
was shining pretty brightly. Mountain tops thickly covered
with snow.

37-9 | 37.2 | 35-9] 0-0 pm.
53-6 | 45-9 | 38:2 | 4-30 p.m.
60:7 | 52-6 | 46-9 | 11-15 a.m.
48-3 | 45- | 41-4 | 7-30 p.m. » 28. A, fine. Dense mist on Gabel; light do. on the Pike; fine
55-6 | 51-6 | 48-8 | 1-30 p.m. and gleamy at the other stations. Mountain tops thickly
47-3 | 46.4 | 45.4 | 7-0 pm. covered with snow.

mye e41-3 | 38- | 0-0 p.m.
45: 43-3 | 40-2 | 2-30 p.m.
41. 38-7 | 35-9 | 1:0 p.m.
26- 23-6 | 11-6 | 1-30 p.m.

April 2. A, on leaving, dark and misty; on returning, fair and mild.
B, wet, but below the mist. C, fair, below the mist. D,
misty, with clear intervals. E and F, thick mist, but fair.

43-0 | 40-0] 35-5 | 2:8 p.m. May 1. Fine and sunny; no mist at any of the stations.

ee | 22S") jy 0-16. pan. 5, 981. Fine and clear throughout.

June 30. Misty at intervals on Gabel and the Pike; clear at the other
stations.
Sca FELL PrKe. (G)
August 2. Fine and gleamy; no mist at any of the stations.

Dry Wet | Dew

Bulb. | Bulb. | Point. eu

ct ,, 9l. Thick mist with small misty rain on the Pike; below the mist

- Z a h. m. at the other stations.
19. 19-1 19- 0:0 p.m.

19-9 | 20- 19-9 |11-45 a.m. | Sept. 30. Very misty with small misty rain on the Pike; clear at the
28: 27-9 | 27-5 | 3-0 p.m. other stations.

43- 38-5 | 333 | 11-30 am.
49:3 | 44.3 |) 39. 9.15 a.m.
Begg |). 38 E e615 pam)” Nove 80: Misty on Lingmell, Gabel, and the Pike; clear at the other
47-3 45-9 44.4 11-30 a.m. stations.

41- 40-8 | 40-5 | 5:45 p.m. .
35.4 | 35.2 | 34-9 |10-30 am.| Dec. 31. Fine and gleamy at all the stations.

Oct. 31. Misty on the Pike; clear at the other stations.

39-9 | 39-2 | 38:3 | 1-0 p.m.
29-8 | 29-8 | 29-8 | 11-15 a.m.
16-5 | 15-6 8-8 | 11-45 a.m.

34.1 | 32-9 | 31-1 | 0-48 p.m.
34-6 |; 33-8 | 31-5 | 10-30 am.

VOL. XXI. PART I. 2F

106 DR MILLER ON THE METEOROLOGY OF

TABLE XXXI.—DeEpDucTIons relative to the HumIpiITY of the ATMOSPHERE at the
MountTAIN STATIONS, in the year 1853.

WEIGHT OF | 56
__ Vapour. |3 =
2 = = 6 vat rice £ 5 Bs
STarion. 3 Fes sy S | eSl/kas
Br ee » | £2 | 3828] see
A | & ral Sq | Se=| 3B,
| 3 ° a= ed ae |
| & |@33|a8
h. m. Feet. F; 2 olan z Grains. | Grains.
Wastdale Head, (10-2 a.m.) 247 above the Sea, | 46-5 | 43-0 | 38-3 | 2:96 | 0-86 .
Do. do. , (5:34 p.m.) is . 48-8 | 44.3 | 39-6 | 2-98 | 1-14 72
Brant Rigg, : : 924 3 = 45-4 | 42-0 | 37-3. | 2:87 | 0-81 775
Stye Head, 4 =i, M448eee # 43-0 | 40-0 | 35-5 | 271 | 0-70 .
Lingmell, ; svi 7/74 - 41-2 | 39-1 | 35-8 | 2-74 | 0-47 -8:
Sprinkling Tarn, y a900) Se " | 39-9 | 37-8 | 34-2' | 2-61 | 0-47 :
Great Gabel, : tot 82920" 36-8 | 35-2 32-6 | 2-42 | 0-36 87%
Sea Fell Pike, . = G8866 vis, e 34-1 | 32-9 | 31-1 | 2-28 | 0-25 .
SSS a
REMARKS.

1851.—The almost incredible quantity of 38°86 inches of rain precipitated on
the “ Stye” or shoulder of Sprinkling Fell in a single month (January) is, I be-
lieve, without a parallel in the temperate zone, or even in tropical latitudes, except
in some of the mountainous regions of India during the prevalence of the mon-
soon.

Respecting the comparatively small amount of rain (14°47 inches) registered
at Wastdale Head in January, the registrar says, “‘ There were many wet days in
the month of January, but few heavy falls of rain; you will perceive we had much
heavier falls in the month of February.” In other parts of the Lake District, it
required no instrumental means to impress upon the oldest residents the convic-
tion, that this was one of the wettest months within their recollection.

1852.—This year is distinguished by several striking peculiarities and abnor-
mal conditions of climate, of which the most prominent are,—the large amount
of rain, and its very unequal distribution over the different seasons, and the
enormous and unprecedented downfall in the first two and. last two months of
the year. As regards the Lake District generally, the year 1852 exhibits by much
the largest quantity of rain recorded in any annual period since the experiments
were commenced in 1844; though the fall at Wastdale Head and Seathwaite was
exceeded, in 1848, by 5°74 and 4°15 inches, respectively. At the coast, the depth
in 1852 was exceeded in only three of the last 20 years—viz., in 1835, 1836, and
1841, in which the atmospheric precipitation reached 54:13, 58°97, and 55:97

THE ENGLISH LAKE DISTRICT. 107

inches, respectively. It may be observed, that the fall of rain in 1852 has been
relatively much greater in the Westmoreland than in the Cumberland portion of
the district.

In January and February, the fall at Seathwaite was 47°70 inches, and, in
November and December, it amounted to 50°30 incites; so that, of 156°74 inches
precipitated at the head of Borrowdale in 1852, exactly 98 inches descended in
four months, whilst 58:74 inches were distributed over the remaining eight months
of the year.

On the 11th and 12th of December, the quantity of rain measured at Stone-
thwaite (for 48 hours) was 9°11 inches; on five days in this month, the fall
amounted to 16°36 inches ; and, on eight days, to 20:97 inches!!

1853.—Among several anomalous and opposite characteristics presented by
the years 1852 and 1853, the departure from the average in the rain fall is the
most opvious and remarkable. While the former is the wettest, the latter is the
driest year within the period comprehended by the Lake District observations.
In 1852, the depth of water deposited by the atmosphere at Seathwaite was
equivalent to 156°74 inches; and, in 1853, to 113-69 inches; a difference of 43
inches—nearly corresponding to the average annual fall at Whitehaven in the
last ten years.

Notwithstanding the great deficit in the quantity of rain, the wet days at Seath-
waite are two more than the average number; and, at Whitehaven, they amount
to four, and, at the Flosh, to eight more than the number in the preceding memor-
ably wet year. In both years, the Springs were unusually dry, and the fall of
rain in the first six months was below an average quantity. The depth of rain
measured at Seathwaite in December, was 14 inch; in the corresponding month
of 1852, the fall amounted to 32°83 inches; and, at Stonethwaite, to 33:03 inches.

The Table (No. XXII.) exhibiting the rain fall in the Lake District Valleys
during the last ten years, requires very little comment.

The greatest annual fall at Seathwaite was 160-9 inches, in 1844; the least,
113°7 inches, in 1853. The greatest monthly fall was 32°83 inches, in December,
1852. The greatest depth measured in 24 hours was 6°62 inches, in November,
1846; and, in 48 consecutive hours, 9°62 inches on the 25th and 26th of November,
1845, and 9-74 inches, on the 8th and 9th of October, 1846.

Tue Mountain Gauces.—The following tables shew the excess or deficiency
per cent. of the principal Mountain Gauges over or under the quantity of rain
received by the adjacent valleys, both in the summer and winter months, in each
year since the instruments were erected in 1846. The positive sign signifies that
the quantity is greater, and the negative sign that it is less, than the fall in the
valley in the same period. a

108 DR MILLER ON THE METEOROLOGY OF
SuMMER MONTHS.

WASTDALE HEAD. BoORROWDALE.

Sca FELL.

Sprinkling Brant Seatollar
pages a Gt. Gabel, Tarn, 1900 Stye Head, Rigg, Conran The Stye,
The Pike, Lingmell, 2925 feet 1448 feet ? 948 feet
3166 feet | 1778 feet | above Sea.
above Sea. | above Sea.

feet above piaee Boal 924 feet 1338 feet above Sea.
ea. above Sea. | above Sea.

+ 29-5
+ 29-5
+ 41-5
4 178
+ 35-3
a
+
+
+

36-6
33-0
30-3 |

+++t+++4++

253-0 | + 136-7

+ SEb6i)-- teins oed

* The percentages in 1846 and 1847 shew the mean of the two years, which were tabulated together.

WINTER MONTHS.

WASTDALE HEaD. BoORROWDALE.

Sca FELL.

sip scant ae ee

The Stye.
The Pike. | Lingmell.

[S465 os — 42-5 oo nual : 15-2

1847. F — 42-5 eee : “ : 15-2

1848. . . | Leaked. see
TS495. aes — 43-5 | —28-8
WS505 a Vs — 33-7 | -—13-9
TSd5dear ids. — 45-1 — 3-0
Sil. ee — 39:5 | —14:3
USSaF. 2p) « — 53-7 | —24-9

Algebraical Sums.| — 300-5 | — 84-9

— 42-9 | —16-9

* From the falling off in the relative amount of rain at Stye Head in the winter months of 1851, it is
suspected that some of the water may have been lost by leakage.—See Introductory Remarks.

The relative quantity of rain received by the gauges on the Stye or Sprinkling
Fell, and on Seatollar Common, in Borrowdale, seems to be very variable. In
the Summer months of 1850 and 1851, Seatollar Common, 1338 feet above the
Sea, received 4 per cent. and 6-3 per cent. respectively more rain than the dale

THE ENGLISH LAKE DISTRICT. 109

at Seathwaite, and, in the Winter months of those years, 0°3 per cent. and 3:4
per cent. respectively /¢ss rain fell on the mountains than in the valley. But, in
1852, 3 per cent. /ess rain fell in the Summer and 1°5 per cent. more in the Winter
months, than descended in the subjacent valley ; and, in 1853, the fall is less than
in the valley, both in the Summer and the Winter months. In the years 1850
and 1851, the relative excess of rain on the Stye, 948 feet above the Sea, was 27°6
and 21:5 per cent., but in 1852 and 1853, only 8°1 and 9°7 per cent. respectively ;
hence, in the memorably wet year 1852, this station received nearly 2 inches
less rain than in 1851, and 21 inches less than in 1850.

The above tables shew that on the mountains, the greatest depth of rain in-
variably obtains at Sparkling Tarn, 1900 feet above the sea level. The current
which brings our principal supply of rain is the South-west. It is characterized by
a high temperature—is generally at or near the point of saturation—and, in most
heavy and continuous rains, the depth of the stratum of vapour is considerable,
extending from a thousand feet or less above the sea to probably 4000 or 5000 feet
above it. In passing over the comparatively level tract of country between the
coast and the mountain ranges, rain is deposited, but with little diminution in
the temperature of the gases or vapour. The current is at length arrested in its
progress by the hills—the vapour in contact with the bases of the mountains is
subjected to more rapid condensation, during which it gives out a portion of its
latent heat in a sensible form, whereby the temperature of the surrounding mass
of air and vapour is increased, and, by virtue of its increased elasticity, it rises to
a greater height; the diminution of temperature due to the increased elevation
causes fresh deposition—the surrounding medium is again warmed—the vapour
ascends still higher—is farther cooled, and more water forced from it; and thus,
the same operation is continued and repeated, so long as an adequate supply of
vapour is furnished from beneath. Hence, in the upper regions of the atmosphere,
there is a vertical as well as a lateral current of vapour constantly rushing in to
supply the loss by precipitation.

In ascending from the valley, the amount of vapour which the atmosphere is
capable of supporting or containing in mechanical combination is found to diminish,
while the difference between the air and dew point temperatures also gradually
decreases. There must therefore be a point of elevation, where the quantity of
vapour and the degree of humidity will combine to produce a maximum deposit
of rain in a given time; and this plane of greatest condensation is found, in the
English Lake District, at or about 2000 feet above the sea-level.

It does not follow, from what has just been stated, that the same law would
hold good in the open atmosphere, (supposing it were possible to plant a gauge
therein at an altitude of 2000 feet) because the rate of cooling upwards is much
more sudden in ascending on the surface, than obtains in rising abruptly from the
surface, as in a balloon; consequently, the temperature at any given elevation on

VOL. XXI. PART I. 26

110 DR MILLER ON THE METEOROLOGY OF

a mountain, as 2000 feet, is lower, and the condensation and precipitation of the
warin oceanic vapour will be more rapid and copious, than at an equal height in
the surrounding atmosphere.

On the other hand, when a Pluviometer is merely removed from a lower to a
higher position in the atmosphere, as from the bottom to the top of a building, the
quantity of rain is found to diminish with the elevation. Thus, the gauge on the
tower of St James’s Church, Whitehaven, on an average of 10 years, has received
12:1 inches, or 28 per cent. less rain than a precisely similar instrument stationed
in a garden, near to and on the same level with the base of the building.

The explanation seems to be, that as in most heavy and continuous rains, the
whole atmosphere up to a great height is charged with and precipitates vapour,
the drops are enlarged by accretion after leaving the summit of the tower. It is
only during heavy showers, when the drops are formed at a great altitude, that
the upper gauge is in excess. In this case, the drops have probably been sub-
jected to evaporation in passing through the comparatively warm and dry stratum
of air intervening between the two instruments.

Among the mountain chains of the Indian Peninsula, Colonel Syxes finds the
maximum fall of rain at 4500 feet, and that above this level the supply is
diminished. The following tables and remarks are extracted from Colonel SyKEs’s
valuable ‘‘ Discussion of Meteorological Observations taken in India,” published
in the Philosophical Transactions, Part ii., for 1850.

Fall of Rain at various Heights in India. (Western Coast.)

Inches.

Mean of Seven Stations on Western Coast, at Sea level, : . 81-70
At 150 feet, Rutnagherry, in the Konkun, , i : : 114-55
. 900 ... Dapoolee, Southern Konkun, . - i 134:96
... 1740 ... Kundalla, the Pass from Bombay to Prons: F 4 141-59
... 4500 ... Mahabuleshwur, mean of 15 years, : - E 254:05
--» 4500 ... Mercara, in Coorg, mean of 3 years, J 5 , 143-35
... 4500 ... Uttray Mullay, Travancore, mean of 2 years, 3 263-21
. 6100 ... Kotergherry, on the Neelgherries, 1 year, : . 81-71
8640 ... Dodabetta, highest point of Western India, 1 year, : 101-24

Uttray Mullay Range—for 1849.

Inches.

At 500 feet, Base of range, 5 : : : ‘ - 99
10 2200"... “Attagherry, : 4 4 : : : 170
- 4500 ... Uttray Mullay, . : 3 : 4 : 250
. 6200 .., Agusta Peak 7 . 194

shew at 6200 feet, 46 inches less rain than at 4500 feet.*
[The greatest depth at Mahabuleshwur in 21 years, was 338°38 inches, in 1849;

* From returns recently published by Dr Burst of Bombay, it appears that in Eastern Inpra
also, the maximum deposit of rain is found at 4500 feet, at which elevation, the annual quantity
amounts (at Cheerapoong) to no less than 610 inches!!_ At Sylhet, 5000 ae above sea level, the
fall is 209 inches; and, at Darjeeling, at 7000 feet, it is 125 inches. At Bombay, on an average of
30 years, the el rain fall is 76°08 inches, and at Calcutta and Madras, for 8 years, it is 66°59
and 52-27 inches, respectively.

THE ENGLISH LAKE DISTRICT. ete

the least, 180-18 inches, in 1838; and nearly the whole of this enormous quantity
falls in the four months of June, July, August, and September, during the pre-
valence of the South-west monsoon. The greatest daily fall was 13-06 inches ;
and the greatest monthly fall, 134°42 inches, in July, 1840.]

“Mr Mriter, in his ‘ Meteorology of the English Lake District,’ has adduced
sufficient evidence to prove that the same law, if it be a law, obtains in England
in mountainous districts, but Mr MitiEer’s elevation of maximum fall is about
2000 feet instead of 4500, asin India. The difference no doubt results from the
differences of latitude and consequent mean temperature, and would indicate that
the stratum of vapour supplying the maximum quantity of rain floats at a less
height beyond the tropics than within them.”

In commenting upon the difference in the receipts of two Pluviometers—one
placed near the ground, and the other above the dome of the Observatory at
Bombay—Colonel Syxes further remarks :—

“ These results therefore are in accordance with Professor Pariurrs’s and Mr
MILLER’s observations, taken at limited heights, but entirely antagonistic to Mr
MILLER’s own observations and those I have supplied in this paper from India,
for heights exceeding a few hundred feet. The supposed law may hold good for
small differences in elevation on the plains, but that law is reversed in mountain-
ous districts.”

On comparing the above Tables with those for the English Lake District, it
will be perceived that the downfall of rain at Seathwaite and its adjacent moun-
tain stations * exceeds the annual receipts at most of the stations in the peninsula
of India, both in the plain, and at moderate and extreme elevations on the
mountain ranges, the excess in the tropical region being chiefly at Mahabulesh-
wur, Mercara, and Uttray Mullay, which, although differing greatly in lati-
tude, lie nearly on the same meridian, and are all the same elevation of 4500
feet above the sea.

In the mountain valleys of our Lake District, the greatest deposit of rain is
always found at the head or Eastern extremity of the dale, because the vapour
on arriving there is further obstructed and confined by the high mountains sur-
rounding it, and, being dashed against their cold rocky sides, increased decompo-
sition ensues; and, as the remaining vapour can only escape by slowly climbing
over the tops, ere the transition or deportation is effected, fresh vapour rushes
in to supply the vacuum produced by condensation; and the precipitation is not
only rapid but continuous, so long as the warm saturated current continues to
flow up or into the valley from the Western Ocean.{ In like manner, more rain is

* The average fall of rain at Seathwaite for 9 years, is 144 inches, and on the Stye or Sprink-
ling Fell for 4 years, 159 inches.

+ Seathwaite, from its position at the head or terminus of the Southern fork of Borrowdale,
which is environed by the lofty mountains, Great Gabel, Glaramara, and Sprinkling Fell, is very
favourably situated for the retention and exhaustion of the Rain-cloud. But, it is probably to the

112 DR MILLER ON THE METEOROLOGY OF

impounded on the mountain passes, and in the hollows and basin-shaped cavities
on the mountains, than on their summits. In passing over the tops, the vesicles
are cooled and rendered heavier, and volumes of vapour flow down into the hol-
lows and gorges, where they are hemmed in as in a cul de sac, and are converted
into water. As decomposition proceeds, fresh masses of mist roll down the slopes,
which in their turn are condensed and precipitated by the surrounding cold high
land, and, as in the former case, the fallis both copious and uninterrupted, while
the vapour in its swift transit over the adjacent peaks is but partially meta-
morphosed into drops of rain.

I also find that a gauge moderately sheltered receives more rain than one near
it fully exposed to the weather. At Seathwaite, there are two rain gauges withina
very short distance of each other,—the one at 10 inches, the other at 22 inches
above the surface. The former is placed in a small garden surrounded by low walls;
the latter is planted in an adjoining large field. On an average of 6 years, the
garden gauge received 3°61 inches annually more rain than the field gauge.
That the difference in the receipts of the two instruments is entirely due to the
degree of exposure, and not to the difference in the heights of the receiving
surfaces above the soil, is clearly shewn by the fact—that when both the gauges
were located in the garden side by side, (as they were from June to December
1846) the higher impounded rather more rain than the lower.

In a former paper, I alluded to the rapid increment in the fall of rain in ap-
proaching the head or terminal point of a valley, and it was shewn numerically,
that the effect of such approach was appreciable at intervals of one or two
hundred yards. ‘The difference in the quantity of water deposited at places
closely contiguous to each other on the mountains is also sometimes surprisingly
great. In the four years 1846-49, Seatollar Common, at 1338 feet, received 19 per
cent. Jess rain annually than the valley at Seathwaite. In August 1849, the first
mentioned gauge was removed 90 yards to the south-westward of its then posi-
tion, and about five feet lower down the mountain. In the four following years,
1850-53, the excess was in favour of the “Common” to the extent of 0°5 per cent.
The only circumstance attending the change which can be supposed materially to
have affected the rain fall, is that of the new locality being somewhat more
sheltered than the old one.

In a previous paper, published in the Philosophical Transactions, (Part i. for
1849) I have endeavoured to account for the great difference in the percentage of
rain between the summer and winter half-year on the mountains, (particularly
on Sca Fell and Gabel) which I attribute conjointly to the loss sustained by the
gauge when the precipitation is in the form of snow, and to the lower altitude of
the principal plane of condensation in the colder months.

copious supply of vapour poured into this narrow valley from the “ Stye” pass—which trends nearly
in the direction of the prevailing aerial current—that Seathwaite is chiefly indebted for the great
excess of its rain-fall over every other locality in the Lake District.

THE ENGLISH LAKE DISTRICT. 1138

Evaporation.—It may not be uninteresting to learn the annual amount of
Evaporation in the immediate neighbourhood of a locality distinguished by so
prodigious a rain fall. The Tables shew that a comparatively small part of the
vapour requisite for the production of the enormous depth of water annually
deposited in the Lake District, is formed over or from the terraqueous surface
constituting the locality.

The chief supply comes from those tropical regions where an unclouded and
almost vertical sun is continually lifting up the waters of the ocean into the at-
mosphere in an invisible form; the warm vesicular vapour thus generated by
evaporation rises to a great height, and is transported by currents into our
Northern climate, where it descends as rain, and maintains the existence of our
lakes, rivers, and springs—while the large amount of sensible heat liberated
during the condensation and conversion of the vapour elevates the temperature
of the mountain valleys above that of the adjacent plains in the colder months,
and no doubt tends materially to modify the climate at all seasons. A cubic
inch of water will form a cubic foot of steam of the same apparent temperature
as the water; but during the process of conversion it has absorbed 1000 degrees
of heat from the surrounding atmospheric space—of which the thermometer gives
no indication till the vapour is reconverted into water, when the latent caloric is
slowly evolved in a sensible form. The amount of perceptible heat yielded up
annually in the formation of 141 inches of rain at Seathwaite, is almost in-
credible, and the extent to which the climate of this naturally inhospitable region
is ameliorated.by this natural provision for equalizing temperature, must be pro-
portionally great. The average depth of water raised by evaporation at White-
haven in the 12 years between 1842 and 1853, is 29-664 inches, and this quan-
tity may be accepted as the liquid equivalent of the average amount of vapour
thrown off by our Jakes in the course of a year. The real amount yielded by the
entire area of the district is of course considerably less. The rain fall in the
Lake country varies from 67 to 141 inches per annum. Of the 141 inches pre-
cipitated at the head of Borrowdale, probably at most 25 inches is supplied on the
spot in a vesicular form; so that the mass of vapour annually imported from lower
latitudes must be equal to 116 perpendicular inches of water—nearly the whole of
which finds its way back again unchanged to its original source—the ocean.

The waters of the ocean cover nearly three-fourths of the surface of the
globe; and, of the 38 millions of miles of dry land in existence, 28 millions be-
long to the Northern hemisphere. It is computed that the depth of water raised
by evaporation from the entire surface of the ocean is about 4 feet per annum ;
while, in tropical seas, the amount converted into vapour cannot be less than
a quarter of an inch daily all the year round, or say 90 inches annually. In the
month of May, the liquid equivalent of evaporation from our lakes occasionally
amounts to 0°25 inch per diem for several days together, and in extremely dry

VOL. XXI. PART I. 2H

114 : DR MILLER ON THE METEOROLOGY OF

periods, it sometimes, though very rarely, reaches {ths of an inch in 24 hours.
On the 22d of May, 1844, 0°430 inch was measured, and on a freezing mixture
being applied to DAntELL’s hygrometer, the dew-point was found at 24° below the
temperature of the air, which was 63°.* The evaporation for the month was
6:280 inches, with only a quarter of an inch of rain.

Surprise is often expressed that vegetation is enabled to retain its vitality,
and even to come forth unscathed from the scorching ordeal to which it is occa-
sionally subjected, in the continuous absence of rain for weeks, and even for
months, as was the case in the spring of 1852, when the entire atmospheric pre-
cipitation in 70 days only amounted to 7ths of an inch of water. But Nature has
provided a check, which prevents the extreme heating and aridity from which the
ground would otherwise suffer under such circumstances. Insummer, the earth’s
surface is not unfrequently heated by the sun’s rays to 100° or upwards, even in this
latitude; but as the soil is a very bad conductor of heat, this temperature does
not penetrate more than a very few inches downwards; and, at a moderate depth,
the day and night temperatures are nearly identical. When the soil has once
become thoroughly desiccated, it loses that capillary action by which excess of
water is ordinarily withdrawn from it; in other words, evaporation ceases, and
the subjacent moisture is thenceforth stored up for the special uses of the vege-
table kingdom: it is absorbed by the roots of trees, shrubs, plants, and grasses,
contributing to their growth and sustentation, as it slowly passes through their
vascular structure into the atmosphere. When rain at length visits the thirsty soil,
it does not recover its absorptive powers all at once; in the meantime, slight
showers are forthwith transformed into vapour as they descend on the heated
ground, while heavy rains flow off from the baked and indurated surface into the
adjacent hollows, drains, and water-courses.

Evaporation is scarcely ever entirely suspended, either during the heaviest
rains, or when the air is apparently saturated with vapour; at least, I have met
with very few instances in which some daily loss was not appreciable to a finely
graduated instrument. This important natural process is also active at very low
temperatures of the air; and it goes on freely from the surface of frozen water,
even when the whole mass is converted into a solid block of ice. From the 11th
to the 16th of December, 1846, during which a brisk breeze prevailed, the loss from
the frozen contents of my evaporation gauge was 0°450 inch, or ‘075 per diem, the
average for the month being ‘033 per diem. In twelve days of frost in February,
1847, the evaporation from the ice was 0°552 inch, or :046 per day, the average daily
quantity for the month being ‘030 inch. During ten days of keen frost between

* Whilst I am revising this paper, (April 21, 1854) Evaporation is unusually active for the sea-
son. The loss from the gauge in the 24 hours preceding 9 a.m., was 0°30 inch, which is the great-
est daily quantity I have recorded in the month of April. During the last 3 days, the maximum
temperature has varied from 65° to 73°, and the complement of the dew-point has ranged from
23°83 to 25°-5—approaching to the extreme of hygroscopic dryness in this climate.

THE ENGLISH LAKE DISTRICT. 115

the 20th and 30th January, 1848, the ice had parted with 0°324 inch, or ‘032 per
diem, the average daily loss for the month being only ‘024 inch. For five days of
December, 1848, the loss was ‘037 per diem, the daily average for the month being
.032; and, from the 1st to the 8th of January, 1849, the depth evaporated was
equivalent to ‘017 per diem, the average daily loss during the month being ~029
inch. Lastly, in the first six days of January, 1854, the loss from the frozen con-
tents of the gauge was 0°219 inch, or 036 per diem, which is identical with the
average daily evaporation in that month. Hence it appears that, notwithstanding
the large amount of heat required not only to liquefy but to vaporize frozen water,
the vapour thrown off by ice in an invisible form exceeds in amount the average
daily evaporation from an equal surface of water, in the winter season. This
apparently anomalous circumstance arises from the extreme dryness of the atmo-
sphere, and its consequently increased capacity for vapour, in severe frosts;
whereas, at other times during the winter, the air is very moist near the sea,
being generally not more than 2° or 3° above the point of saturation.

At Whitehaven, the average amount of Evaporation for the twelve years end-
ing with 1853, is 29:664 inches, and the fall of rain for the same period is 43°02
inches,* so that the depth of water precipitated exceeds that taken up by evapo-
ration at the coast, in latitude 54°30, by 13°357 inches. In the almost tropically
fine and dry year 1842, the evaporation (36°83 inches) exceeded the rain-fall by
2143 inches. The evaporation is not unfrequently in excess in the months of
March, April, May, and September; and, in 1853, the amount of vapour absorbed
by the atmosphere equalled or exceeded that which was restored to the ground
in a liquid form, in seven months of the year.

The evaporation force at the altitudes of our highest mountains appears to be
very feeble, notwithstanding the greatly diminished pressure of the air. At the
summit of Great Gabel, (2925 feet above the sea) there is a vertical cavity in the
rock, which, owing to the almost continuous presence of clouds, the high degree of
humidity, and consequent slight evaporation at this elevation, always contains
water, except in the very driest seasons. It is commonly believed that this “ at-
mospheric spring”’ or well, as it is called, is never empty. The traditionary belief
is, however, not strictly correct. The well was quite dry in the Spring of 1844,
and also in April, 1852.

The Evaporation Gauge is a copper vessel, 8 inches in diameter, and rather
more than an inch and a half in depth. Half an inch of water is accurately mea-
sured and poured into the dish every morning at 9 o’clock, and the loss is ascer-
tained at the end of 24 hours by means of a carefully-graduated tube, reading to
the z¢ooth part of an inch.

The evaporation dish receives a fair proportion of wind and sun, and is
always exposed in the open air during the day, except when rain is falling. At

* The average annual rain-fall for 20 years, at Whitehaven, is 46-59 inches.

116 DR MILLER ON THE METEOROLOGY OF

night, and in wet weather, it is placed under a capacious shed, 9 feet in height, and
open in front. Thus, it is considered that the evaporating surface is freely acted
upon by all the circumstances concerned in promoting the vaporization of water.

The evaporation has now been recorded with scrupulous care, day by day for
twelve years, at this observatory; and it is believed that the results are the best
which have yet been obtained in this country.*

TEMPERATURE AT THE Mountain Strations.—Considerable difficulties have
attended my endeavours to secure the monthly minimum temperature at the
higher mountain stations. The mountain tops consist of an extremely hard and
impenetrable rock,} so that it is impossible to fix in it a pole on which to fasten
the box containing the thermometers. Some years ago, a party of Government
Surveyors, engaged in triangulating from Sca Fell Pike, erected on the summit a
cairn or pile of loose stones, having in its centre a stout pole, which projected
about two feet above the apex of the cairn. To this pole the box containing the
thermometers was originally attached. The box was freely pierced with circular
holes at the sides and bottom, to permit the air to circulate freely through it.
The horizontal thermometers were purposely disposed with a slight inclination
downwards toward the bulb, to counteract, in some degree, the resistance offered
to the contraction of the alcohol by the glass-pin or index; and it was not until
the observations had been taken for a considerable time, that it was suspected,
from the extreme degree of cold indicated, that strong currents of air passing
through the apertures in the wooden case might cause the indices to descend to-
wards the bulb, and so produce erroneous readings.

It was subsequently found that the apprehended source of error was real, and
that it must have been continuously in more or less active operation, when the
air was in rapid motion.

In the year 1851, I determined to make a renewed attempt to obtain correct
thermometrical indications from self-registering instruments ; and, that I might
not have to depend entirely on one instrument, I also stationed minimum thermo-
meters at Sprinkling Tarn and on the Gabel, at 1900 and 2925 feet respectively
above the sea. A rock was selected which stood about four feet above the sur-
face, or pieces of stone and rock were collected and piled up to that height: the
thermometer boxes were placed thereon, and built in at the top and sides with
loose stones, so as to secure them from being displaced by the wind, and, at the
same time, to give the air ready access to the instruments through the interstices
of the stones and augur-holes in the cases. So placed, the instruments were also
concealed from tourists and other casual mountain visitors.

* In compiling the paragraph on Evaporation, I am indebted for several interesting facts to an
elaborate paper “* On the Physical Geography of Hindostan,” by Dr Burst, LL.D., ‘which appeared
in the last (April) number of the Edinburgh New Philosophical Journal.

+ An extremely indurated Green slate and Porphyritic slate.

THE ENGLISH LAKE DISTRICT. ve

In consequence of unforeseen difficulties, and the fatal occurrence above men-
tioned, I fear that all the observations obtained prior to July 1851 are open to
some degree of suspicion, and it is with no little regret that I feel compelled to
reject them in toto from the tables.

In the observations made subsequently to July, 1851, every reliance may be
placed ; indeed, I could not have much greater confidence in their accuracy, if the
readings had all been taken by myself, as, about this time, I was fortunate in secur-
ing the services of a very careful and efficient registrar, who thoroughly understood
the work he had to attend to, and who gave entire satisfaction in the performance of
his duties up to the close of the year 1853, when the experiments were discon-
tinued.

The mean difference between the absolute minima temperatures in the valley
at Seathwaite and on Sca Fell Pike was, in 1852, 13°:8, and, in 1853, 12°:7, or an
average of 13°:2 in 2798 feet. ‘This result, which may be assumed to represent the

‘average of the extreme difference at night in each month, is somewhat less than I
had anticipated, as it exceeds by a small fraction only the observed mean depression
during the day, derived from observations taken under ordinary circumstances.
In examining the tables of temperature for the Mountain Stations, it must be
borne in mind that it is impossible to ascertain thé actwal minimum temperature
of the air on the mountains in the winter months, as the boxes containing the
instruments (although raised four feet above the surface) are then generally
covered more or less thickly with snow. In the winters of 1852 and 1853, the
maximum depth of snow varied from 12 to 24 inches.

The effect of snow in keeping warm the earth and objects upon it is well
known. Its slow conducting power is shown indirectly by the high relative tem-
perature indicated by the thermometer at Sprinkling Tarn, in January, February,
March, and April, 1853. The average difference between the thermometers on
Sca Fell and at Sprinkling Tarn is 5°; but for the first four months of 1853, the
average difference was 12°2. The quantity of snow deposited at the Tarn (pro-
bably from its more sheltered position) is invariably greater than on the Pike; at
the middle and end of February, the excess was six inches, and by this eztra
depth the temperature was raised 7 degrees. Mr GLaIsHErR frequently found a
thermometer on the grass slightly covered by snow’to read 8° or 9° higher than one
on grass clear of snow; and, in one instance, when the temperature fell suddenly,
the difference (under three inches of snow) was no less than 34°; and when the
thermometer on grass clear of snow had risen 30°, (from—6° to + 24°) no variation
had taken place in that under the snow, which still read 28°. Snow being so
perfect a non-conductor of heat, evidently prevents to a high degree the loss of
heat by radiation from bodies covered by it; and it also prevents the loss of heat
from such bodies by conduction, at times when the temperature of the air is
lower than they are. We may therefore fairly assume, that when the self-regis-

VOL. XXI. PART I. 7a

118 DR MILLER ON THE METEOROLOGY OF

tering thermometers on Sca Fell and Gabel, buried under 12 to 18 inches of snow,
indicated a minimum of 8°, 9°, or 10°, the veal temperature of the air at these
elevations must have been considerably below the zero point of FAHRENHEIT’s scale.

The comparatively high readings of the night thermometers in the winter
months being thus fully accounted for, I have endeavoured to discover whether there
are any circumstances or conditions ordinarily present during the night hours,
which may tend to modify the temperature of the upper regions of the atmosphere
when the sun is below the horizon. The cooling effect produced by terrestrial radia-
tion on the stratum of air in immediate contact with the earth, appears to extend to
the ordinary height of a thermometer suspended in the air (4 feet), since we find
the coldest nights, both on the surface and at 4 feet above it, are always those in
which the principal conditions essential to free radiation are present—a serene
and unclouded sky. The atmosphere is usually in more rapid motion on high
lying lands and hills, than on the plains. Hence, plants growing on high exposed
ground, where the air is more disturbed than in the valleys, suffer less from frost.
Now, to whatever extent the temperature at 4 feet above the earth’s surface is
depressed by radiation, the depression at an equal altitude above the tops of the
mountains will in general be much less, inasmuch as a calm state of the air very
seldom obtains in these elevated regions.* The lateral atmospheric currents,
rarely absent, will supply a large portion of the heat lost by conduction consequent
on the radiation from the very limited areas constituting the mountain tops or
peaks. Moreover, the large amount of heat thrown off by the earth’s crust be-
tween sunset and sunrise may tend to keep up the temperature of the upper
strata of the air during the night. But for this supply of heat communicated by
terrestrial radiation, ice and snow would probably form much earlier in the autumn
and perhaps rarely be absent during the summer months, on such elevated peaks
as Sca Fell and the Gabel.t .

In 1852, the mean of the absolute monthly minimum temperature on Sca Fell
at 4 feet above the top, and perfectly protected from radiation, was 26 less than
the temperature on the grass at Seathwaite similarily determined.

The mildness and equability of the climate in our sequestered mountain valleys
was further exemplified during the periods of extreme cold which prevailed over
the country generally, in December and January last. The lowest temperature

* T have only met with one instance of the presence of a strong breeze in the valley, when the air
was quite motionless on the top of a mountain. On the 21st of April 1848, I find the following
memorandum in the register-book,—‘“ Ascended Sca Fell, &c. There was a fresh breeze and appear-
ance of rain on our leaving the valley at 115 40™ a.m., but before attaining the summit of Lingmell
(1778 feet) the air became perfectly calm, and so continued till we had again reached the foot of the
mountain. We were surprised to find that a strong breeze had prevailed in the valley during our
absence on the Fell; and it continued to blow fresh throughout the evening. The clouds (Cumuli)
were evidently electric, and generally below the summit of Sca Fell. We passed through one in de-
scending, and a distant peal of thunder was heard from the top.

+ The writer saw a patch of snow on Sca Fell, on the 15th of June, 1843.

THE ENGLISH LAKE DISTRICT. 119

at Seathwaite, in December, was 19°, and in January 18°. On December 16th,
the thermometer at Manchester and Linslade fell to 6°, and, at Wakefield, to 9°°5;
on January 34d, it fell at London to 10°; and, in the Midland Counties, Mr Lowe
estimated the extreme of cold at 4° below zero.

The greatest depth of snow on the ground at one time in the vales of Wastdale
and Borrowdale was about 3 inches. The simultaneous fall at Liverpool and
London was 12 inches. On January 3d, the drifts over England and Wales,
according to Mr GuaisHER, varied from 3 feet to 10, 12, and 15 feet; they were
very deep at Derby and at Grantham, and upon the Norfolk coast.

HyYGROMETRICAL OBSERVATIONS AT THE Mountain Stations.—The hygrome-
trical observations are so consistent with each other, and the resulting humidity
of the atmosphere at the different elevations is so accordant with theoretical
reasoning, that they carry with them a conviction of the faithfulness and of the
care with which they must have been taken and recorded. Ihave not attempted
to correct the dry and wet bulb observations at Wastdale, for the variation in
temperature corresponding to the different hours in the day at which the moun-
tain readings were taken, as the law of the horary fluctuation in the temper-
atures of the air and of evaporation for this latitude is unknown.

The very valuable tables compiled by Mr Guaisuer for the latitude of Green-
wich, it is believed would not apply to this district, and any forced or modified
application of them to a mountain valley would be almost certain to vitiate the
results. The chief points aimed at were, to ascertain the complement of the dew
point and the relative degree of humidity at various heights above the sea and
valley, and these, by far the most important deductions, will be but slightly if at
all affected, by the interim variation of the air and evaporation temperatures in the
valley. The observations are therefore tabulated as they were taken on the spot,
simply corrected for slight instrumental errors.

In computing the decrease of temperature upwards in the atmosphere, the
temperature assumed for the valley is the mean of the two observations taken on
leaving and returning to the hamlet of Wastdale Head.

The hygrometrical results for the years 1852 and 1853 are in essential accord-
ance with each other, and show that whilst the absolute quantity of vapour in the
atmosphere gradually diminishes, the degree of humidity (or the dampness of the air
relative to its temperature) proportionately increases, in ascending above the compa-
ratively level surface of the earth.

The only exception to the law occurs on Lingmell, where the humidity indi-
cated in both years is slightly greater than at Sprinkling Tarn, about 120 feet above
it—the additional quantity of vapour requisite to produce complete saturation
being the same at both places. The stations are situated at opposite extremities
of the valley, and the difference is no doubt attributable to local causes. In 1852.

120 DR MILLER ON THE METEOROLOGY OF

the humidity indicated at 3166 feet was rather less than at 2925 feet. This
anomaly, though probably accidental, is coincident with the fact, that the average
annual fall of rain on Great Gabel exceeds that on Sca Fell by 4°70 inches.

The results enable us to determine approximately the rate of cooling of the
atmosphere by expansion, in ascending on the earth’s surface above its general level.
This may be computed by two independent classes of observations—either by the
observed differences in temperature between the valley and Sca Fell and Gabel, or
by the monthly minima recorded by self-registering thermometers at Seathwaite
and the mountain stations.

In 1852, the observed mean difference in temperature between the Vale of
Wastdale and the summit of the Pike was 12°-7, and, in 1853, 13°-5; the bien-
nial mean is 13°:1 in 2919 feet, showing a fall of 1° in every 222°8 feet of elevation.
In the same years, the depression between the valley and the top of the Gabel
was 11°°6 and 12° respectively, in 2678 feet; or a mean rate of cooling by dimi-
nished pressure equivalent to 1° in 2269 feet, during the day.

The difference between the absolute monthly minima at Seathwaite and on
the Pike was, in 1852, 13°°8, and, in 1853, 12°°7, in 2798 feet,—the mean result
indicating a fall of 1° in every 212 feet, at night. A similar comparison with the
Gabel gives a depression of 1° in 218°5 feet. The combined results of the day
and night observations give a fall of 1° in each 220 feet of elevation.

The depression in the Dew Point between the valley and Sca Fell Pike was, in
1852, 94, and, in 1853, 7°8—the combination showing a fall of 1° in 339-4 feet,
in a perfectly saturated atmosphere. On the Gabel, the descent in those years
was 7°°3 and 7°:0 respectively, exhibiting a mean variation in the vapour point of
1° in every 377 feet. The average result is a descent in the dew-point of 1° in
358°1 feet in height, with a simultaneous fall of 1° in every 224°8 feet in the
temperature of the mechanically combined and invisible gases and vapour con-
stituting the atmosphere.

The decrease of temperature in ascending appears to be more sudden dur-
ing the night than the day; and as the mountain thermometers were thickly
covered with snow in January, February, March, and December, 1853, the mini-
mum temperature recorded in those months and also the annual mean must be
considerably higher than would have been indicated had the instruments been
freely exposed to the air. It is therefore concluded that the rate of cooling up-
wards by expansion is in reality more rapid than is shown by the result elimi-
nated from the mean of the day and night observations, or 1° in every 220 feet
of ascent. The variation indicated by the night observations alone (1° in 215 feet)
is probably nearer the truth.

The difference in temperature between the valley and the tops of the moun-
tains varies greatly, according to the amount of cloud, the presence or absence of
mist on the mountains, and the height of the under surface of the Stratus or

THE ENGLISH LAKE DISTRICT. 121

Cirrostratus above the valley. When the mountain is enveloped in mist quite
down to its base, particularly if accompanied by deposition, the difference in
temperature does not exceed 7 or 8 degrees; while, under a perfectly clear and
cloudless sky, it amounts to 18 or 20 degrees. By examining the Hygrometri-
cal Tables in connection with the simultaneous records of the state of the weather,
the variation of temperature under various conditions of the atmosphere as to
clearness and humidity may be computed.

The effect of dense mist in assimilating the temperature of the different strata
of the atmosphere (by emission of its latent heat during condensation) is shown
in the observations of September 9th, 1847, taken on Snowdon in North Wales,
when the depression in 3571 fect was scarcely 10 degrees.

Dr Burr gives the temperature on the Brocken, in 51°51’ north, 3500 feet
above the sea, 33°°8; at Gottingen, 51:30’ N. 480 feet above the sea 47°—a dif-
ference of 13°°2 in 3020 feet; and at Munster, in the same latitude, 190 feet
above the sea, 49°-1—a fall of 15°°3 in 3310 feet. In tropical latitudes, the low-
ering of the temperature is much less sudden. On the table-lands of Mexico,
at 6990 feet, the mean temperature, according to Humpotpr, is 61°34; and at
Vera Cruz, on the sea-coast, in the same latitude, it is 77 degrees. At Quito,
nearly under the equator, (0°7’ 8.) 8970 feet elevation, the temperature is 59:1,
and, at the coast, 78°8 degrees.

The conditions of the decrease of temperature in ascending on the earth’s
surface and from the earth’s surface seem to be very different.

From the observations made during four balloon ascents at Kew in the
autumn of 1852, the number of feet of height corresponding to a fall of 1°
Fahrenheit was, as under :—

On August 17th, ; 3 : 292-0 Feet.
20th, : : ; 290-7

On October 21st, i ; ‘ 291-4

On November 10th, : : tk 312°0

All the ascents, however, show an increasing degree of humidity up to the
altitudes of the highest English mountains.

In a former paper, I ventured to remark, “ The degree of humidity increases
upwards from the earth’s surface, and the condition or combination of condi-
tions most favourable for the condensation and precipitation of vapour in the
greatest abundance will probably be found somewhere about 2000 feet above the
sea-level. It is assumed that the atmosphere is generally near the point of
saturation at and above 2000 feet; but as the air temperature decreases with
every farther increase of elevation, its capacity for vapour is proportionately
diminished, and consequently there will be less to precipitate than at the point
where the temperature of the air and that of the dew-point first begin to balance

VOL. XXI. PART I. 2K

122 DR MILLER ON THE METEOROLOGY OF THE ENGLISH LAKE DISTRICT.

each other.’* This prediction is signally verified by the results of the hygrome-
trical observations taken on the mountains, in the years 1852 and 1853.

It is proposed to follow up and conclude the series of annual papers on the
Meteorology of the Lake District, by an essay “‘ On the Physical Geography of the
English Lake and Mountain District,” for which I am now engaged in collecting
materials. This treatise, in addition to the meteorological facts and results
arrived at in the course of this inquiry, and the aerial phenomena common or
peculiar to mountain localities, is intended to embrace the subjects or sciences
usually included under the head of ‘“ Physical Geography,”—as the Geology,
Botany, Ornithology, and Entomology of the district, in connection with cli-
mate and elevation ; and special attention will be directed to the plants and in-
sects (Lepidoptera) indigenous to the mountain regions. As the English Lake
District presents a wide and rich field for research in these departments of
science, it is hoped that, with competent assistance, this work will not be wholly
destitute of interest or importance to those occupied in similar investigations, in
other and widely different localities.

* Philosophical Transactions, Part ii., 1849.

OBSERVATORY, WHITEHAVEN,
April 15, 1854,

( 123 )

IX.—On the Dynamical Theory of Heat. Part V. Thermo-electric Currents.
By Witi1am THomson, M.A., Professor of Natural Philosophy in the Uni-
versity of Glasgow.

(Read 1st May 1854.)

Preliminary §§ 97-101. Fundamental Principles of General Thermo-dynamices
recapitulated.

97. Mechanical action may be derived from heat, and heat may be generated
by mechanical action, by means of forces either acting between contiguous parts
of bodies, or due to electric excitation ; but in no other way known, or even con-
ceivable, in the present state of science. Hence Thermo-dynamics falls naturally
into two Divisions, of which the subjects are respectively, the relation of heat
to the forces acting between contiguous parts of bodies, and the relation of heat to
electrical agency. The investigations of the conditions under which thermo-
dynamic effects are produced, in operations of any fluid or fluids, whether
gaseous or liquid, or passing from one state to the other, or to or from the
solid state, and the establishment of universal relations between the physical
properties of all substances in these different states, which have been given
in Parts IV. of the present series of papers, belong to that first great Division
of Thermo-dynamics—to be completed (as is intended for future communica-
tions to the Royal Society) by the extension of similar researches to the thermo-
elastic properties of solids. The second Division, or Thermo-electricity, which
may include many kinds of action as yet undiscovered, has hitherto been investi-
gated only as far as regards the agency of heat in producing electrical effects in
non-crystalline metals. In a mechanical Theory of electric currents, communi-
cated to the Royal Society, Dec. 15, 1851,* the application of the General Laws
of the Dynamical Theory of Heat to this kind of agency was made, and certain
universal relations precisely analogous to the thermo-elastic properties of fluids
established in the previous treatment of the First Division of the subject, were
established between the thermo-electric properties of non-crystalline metals. The
object of the present communication is to extend the theory to the phenomena of
thermo-electricity in crystalline metals ; but as recent experimental researches on
air have pointed out an absolute thermometric scale,} the use of which in express-

* See “ Proceedings” of that date, or Philosophical Magazine, 1852, where a sufficiently complete
account of the investigations and principal results is given.

+ That is a scale defined without reference to effects experienced by any particular kind of matter.

Such a scale, founded on general thermo-dynamic relations of heat and matter, and requiring reference
to a particular thermometric substance only for defining the unit or degree, was, so far as I know,

VOL. XXI. PART I. al

124 PROFESSOR W. THOMSON ON THE

ing the general laws of the dynamical theory of heat, both leads to a very concise
mode of stating the principles, and shows the most convenient forms of the expres-
sions brought forward in my former communication, the whole subject of thermo-
electricity in metals will be included in the theoretical investigations now com-
municated. I shall take the opportunity of introducing developments and illus-
trations, which, although communicated at the meeting of the Royal Society
along with the original treatment of the subject, did not appear in the printed
abstract; and I shall add some experimental conclusions which have since been
arrived at, in answer to questions proposed in the former theoretical investigation.
98. Before entering on the treatment of the special subject, it is convenient to
recal the fundamental Laws of the Dynamical Theory of Heat, and necessary to
explain the thermometric assumption by which temperature is now to be measured.
The conditions under which heat and mechanical work are mutually convert-
ible by means of any material system, subjected to either a continuous uniform
action, or a cycle of operations at the end of which the physical conditions of all
its parts are the same as at the beginning, are subject to the following laws :—
Law I. The material system must give out exactly as much energy as it takes
in, either in heat or mechanical work.
Law II. If every part of the action, and all its effects, be perfectly reversible,

first proposed in a communication to the Cambridge Philosophical Society (Proceedings, May 1848,
or Philosophical Magazine, October 1848). The particular thermometric assumption there suggested,
was that a thermo-dynamic engine working to perfection, according to CarNo7’s criterion, would give
the same work from the same quantity of heat, with its source and refrigerator differing by one degree
of temperature in any part of the scale; the fixed points being taken the same as the 0° and 100° of
the centigrade scale. A comparison of temperature, according to this assumption, with temperature by
the air thermometer, effected by the only data at that time afforded by experiment, namely, Recnavur’s
observations on the pressure and latent heat of saturated steam at temperatures of from 0° to 230° of
the air thermometer, showed, as the nature of the assumption required, very wide discrepance, even incon-
veniently wide between the fixed points of agreement. A more convenient assumption has since been
pointed to by Mr Jouxe’s conjecture, that Carnor’s function is equal to the mechanical equivalent of
the thermal unit divided by the temperature by the air thermometer from its zero of expansion; an
assumption which experiments on the thermal effects of air escaping through a porous plug, undertaken
by him in conjunction with myself, for the purpose of testing it, (Philosophical Magazine, Oct. 1852,)
have shown to be not rigorously but very approximately true. More extensive and accurate experi-
ments have given us data for a closer test (Phil. Trans., June 1853), and in a joint communication
by Mr Jouxe and myself to the Royal Society of London, to be made during the present session, we
propose that the numerical measure of temperature shall be not founded on the expansion of air at a
particular pressure, but shall be simply the mechanical equivalent of the thermal unit divided by
Carnot’s function. We deduce from our experimental results, a comparison between differences on
the new scale from the temperature of freezing wuter, and temperatures centigrade of ReGNnauLt’s
standard air thermometer, which shows no greater discrepance than a few hundredths of a degree, at
temperatures between the freezing and boiling points, and, through a range of 300° above the freezing
point, so close an agreement that it may be considered as perfect for most practical purposes. The
form of assumption given below in the text as the foundation of the new thermometric system, with-
out explicit reference to Carnot’s function, is equivalent to that just stated, inasmuch as the formula
for the action of a perfect thermo-dynamic engine, investigated in § 25, expresses (§ 42) that the heat
used is to the heat rejected in the proportion of the temperature of the source to the temperature of
the refrigerator, if Carnor’s function have the form there given as a conjecture, and now adopted as
the definition of temperature.

DYNAMICAL THEORY OF HEAT. 125

and if all the localities of the system by which heat is either emitted or taken in
be at one or other of two temperatures the aggregate amount of heat taken in or
emitted at the higher temperature, must exceed the amount emitted or taken in
at the lower temperature always in the same ratio when these temperatures are the
same, whatever be the particular substance or arrangement of the material system,
and whatever be the particular nature of the operations to which it is subject.

99. Definition of Temperature, and General Thermometric Assumption.— If
two bodies be put in contact, and neither gives heat to the other, their tempera-
tures are said to be the same; but if one gives heat to the other, its temperature
is said to be higher.

The temperatures of two bodies are proportional to the quantities of heat
respectively taken in and given out in localities at one temperature and at the
other, respectively, by a material system subjected to a complete cycle of perfectly
reversible thermo-dynamic operations, and not allowed to part with or take in heat
at any other temperature: or, the absolute values of two temperatures are to one
another in the proportion of the heat taken in to the heat rejected in a perfect
thermo-dynamic engine working with a source and refrigerator at the higher and
Jower of the temperatures respectively.

100. Convention for thermometric unit, and determination of absolute tempe-
ratures of fixed points in terms of it.

Two fixed points of temperature being chosen according to Sir Issac Nrew-
TON’S suggestion, by particular effects on a particular substance or substances,
the difference of these temperatures is to be called unity, or any number of units
or degrees, as may be found convenient. The particular convention is, that the
difference of temperatures between the freezing and boiling points of water under
standard atmospheric pressure shall be called 100 degrees. The determination
of the absolute temperatures of the fixed points is then to be effected by means
of observations indicating the economy of a perfect thermo-dynamic engine, with
the higher and the lower respectively as the temperatures of its source and refri-
gerator. The kind of observation best adapted for this object was originated by
Mr Jou.e, whose work in 1844* laid the foundation of the theory, and opened
the experimental investigation; and it has been carried out by him, in conjunc-
tion with myself, within the last two years, in accordance with the plan proposed
in Part IV.t+ of the present series. The best results, as regards this determina-
tion, which we have yet been able to obtain is, that the temperature of freezing
water is 273°7 on the absolute scale; that of the boiling point being consequently
373°7. Farther details regarding the new thermometric system will be found in

* On the Changes of Temperature occasioned by the Rarefaction and Condensation of Air. See
Proceedings of the Royal Society, June 1844; or, for the paper in full, Phil. Mag., May 1845.

+ On a Method of discovering experimentally the Relation between the Heat Produced and the
Work Spent in the Compression of a Gas. Trans, R.S.E., April 1851.

126 PROFESSOR W. THOMSON ON THE

a joint communication to be made by Mr Joute and myself to the Royal Society
of London before the close of the present session.

101. A corollary from the second General Law of the Dynamical Theory stated
above in § 98, equivalent to the law itself in generality, is, that if a material
system experience a continuous action, or a complete cycle of operations, of a
perfectly reversible kind, the quantities of heat which it takes in at different
temperatures are subject to a linear equation, of which the coefficients are the
corresponding values of an absolute function of the temperature. The thermo-
metric assumption which has been adopted is equivalent to assuming that this
absolute function is the reciprocal of the temperature; and the equation conse-
quently takes the form

= + = + = + ce. = 0;
if ¢, t', &c., denote the temperatures of the different localities where there is
either emission or absorption of heat, and = H, = H,, =H,, &c., the quantities
of heat taken in or given out in those localities respectively. To prove this, con-
ceive an engine emitting a iii H, of heat at the temperature ¢, and taking

in the corresponding quantity HL, at the temperature ¢’; then an engine emitting
the quantity ; ae +H, atv’, and taking in the corresponding quantity 7” (4 —+ =)
at the temperature ¢’; another emitting 7’ (= oes 7) + H, at 7’, and taking in the

corresponding quantity 7” (= +E +=) at ?’”; and so on. Considering n—2
such engines as forming one system, we have a material system causing, by reversible
operations, an emission of heat amounting to H, at the temperature ¢, H, at the

temperature V’,....and Hy» at¢@; and taking in #”» (= —-- .. +=)

at the temperature ¢~”. Now this system, along with the given one, constitutes a

complex system, causing on the whole neither absorption nor emission of heat at

the temperatures 7, 7’, &c., or at any other temperatures than ¢””, &; but giv-

(= oe Hy rl a)
t v

: d : See a
ing rise to an absorption or emission equal to =| ) oS

+ Ho» | at ¢, and an emission or absorption equal to +H, at %. This com-

plete system fulfils the criterion of reversibility, and, having only two tempera-
tures at localities where heat is taken in or given out, is therefore subject to
Law II.; that is, we must have

tm H, -— ,_H n—
Hy = {7D Pe [we (F'+ i a) +H» |
which is the same as
1b hal Le He-y Hey
aL Y = See {oD ro) =0 ; : A : (1).

DYNAMICAL THEORY OF HEAT. 127

This equation may be considered as the mathematical expression of the Second
fundamental Law of the Dynamical Theory of Heat. The corresponding expres-
sion of the First Law is

W+Jd (H+ Hy+ Reet +, 1) + Hay) =0 . - F C (2),

where W denotes the aggregate amount of work spent in producing the operations,
and J the mechanical equivalent of the thermal unit.

S§ 102-106. Initial examination of Thermo-dynamic circumstances regarding
Hleciric Currents in Linear Conductors.

102. Prettier’s admirable discovery that an electric current in a metallic cir-
cuit of antimony and bismuth produces cold where it passes from bismuth to
antimony, and heat where it passes from antimony to bismuth, shows how an
evolution of mechanical effect, by means of thermo-electric currents, involves trans-
ference of heat from a body at a higher temperature to a body at a lower temper-
ature, and how a reverse thermal effect may be produced, by thermo-electric
means, from the expenditure of work. For if a galvanic engine be kept in motion
doing work, by a thermo-electric battery of bismuth and antimony; the current
by means of which this is effected passing, as it does, from bismuth to antimony
through the hot junctions, and from antimony to bismuth through the cold
junctions, must cause absorption of heat in each of the former, and evolution of
heat in each of the latter; and to sustain the difference of temperature required for
the excitation of the electro-motive force, even were there no propagation of
heat by conduction through the battery, it would be necessary continually, during
the existence of the current, to supply heat from a source to the hot junctions,
and to draw off heat from the cold junctions by a refrigerator :—Or, if work be
spent to turn the engine faster than the rate at which its inductive reaction
balances the electro-motive force of the battery, there will be a reverse current
sent through the circuit, producing absorption of heat at the cold junctions, and
evolution of heat at the hot junctions, and consequently effecting the transference
of some heat from the refrigerator to the source.

103. We see then, that in PELTIER’s phenomenon we have a reversible thermal
agency of exactly the kind supposed in the second Law of the Dynamical Theory
of Heat. Before, however, we can apply either this or the first Law, we must
consider other thermal actions which are involved in the circumstances of a
thermo-electric current; and with reference to the second Law we shall have to
examine whether there are any such of an essentially irreversible kind.

104. It is to be remarked, in the first place, that a current cannot pass through
a homogeneous conductor without generating heat in overcoming resistance.
This effect, which we shall call the frictional generation of heat, has been dis-
covered by Jour to be produced at a rate proportional to the square of the

VOL. XX, PART. I. 2M

128 PROFESSOR W. THOMSON ON THE

strength of the current; and taking place equally with the current in one direc-
tion or in the contrary, is obviously of an irreversible kind. Any other thermal
action that can take place must depend on the heterogeneousness of the circuit,
and must be of a kind reversible with the current.

105. Now if in an unbroken circuit with an engine driven by a thermo-elec-
tric current, the strength of the current be infinitely small compared with what
it would be were the engine held at rest, or, which is the same, if the engine be
kept at some such speed that its inductive electro-motive force may fall short of,
or may exceed, by only an infinitely small fraction of itself, the amount required
to balance the thermal electro-motive force of the battery, there will only an infi-
nitely small fraction of the work done by the current in the former case, or of
the work done in turning the engine in the latter, be wasted on the frictional
generation of heat through the electric circuit. In these circumstances, it is
clear, that whatever mechanical effect would be produced in any time by the
engine from a direct current of a certain strength, an equal amount of work would
have to be spent in forcing it to move faster and keeping up an equal reverse cur-
rent for the same length of time; and as the direct and reverse currents would
certainly produce equal and opposite thermal effects at the junctions, and else-
where in all actions depending on heterogeneousness of the circuit, it appears that,
were there no propagation of heat through the battery by ordinary conduction,
Carnot’s criterion of a perfect thermo-dynamic engine would be completely
fulfilled, and a definite relation, the same as that which has been investigated
(§ 25) already by considering expansive engines fulfilling the same criterion,
would hold between the operative thermal agency and the mechanical effect pro-
duced. It appears extremely probable that this relation does actually subsist
between the part of the thermal agency which is reversed with the current and the
mechanical effect produced by the engine, and that the ordinary conduction of
heat through the battery takes place independently of the electrical circum-
stances. The following proposition is therefore assumed as a fundamental hypo-
thesis in the Theory at present laid before the Royal Society.

106. The electro-motive forces produced by inequalities of temperature in a cir-
cuit of different metals, and the thermal effects of electric currents circulating in it,
are subject to the laws which would follow from the general principles of the dynami-
cal theory of heat if there were no condyction of heat from one part of the circuit to
another.

In adopting this hypothesis, it must be distinctly understood that it is only a
hypothesis, and that, however probable it may appear, experimental evidence in
the special phenomena of thermo-electricity is quite necessary to prove it. Not
only are the conditions prescribed in the second Law of the Dynamical Theory
not completely fulfilled, but the part of the agency which does fulfil them is in all

DYNAMICAL THEORY OF HEAT. 129

known circumstances of thermo-electric currents excessively small in propor-
tion to agency inseparably accompanying it and essentially violating those condi-
tions. Thus, if the current be of the full strength which the thermal electro-
motor alone can sustain against the resistance in its circuit, the whole mechani-
cal energy of the thermo-electric action is at once spent in generating heat in the
conductor ;—an essentially irreversible process. The whole thermal agency imme-
diately concerned in the current, even in this case when the current is at the
strongest, is (from all we know of the magnitude of the thermo-electric force and
absorptions and evolutions of heat,) probably very sinall in comparison with the
transference of heat from hot to cold by ordinary conduction through the metal of
the circuit. It might be imagined, that by choosing, for the circuit, materials which
are good conductors of electricity and bad conductors of heat, we might diminish
indefinitely the effect of conduction in comparison with the thermal effects of the
current ; but unfortunately we have no such substance as a non-conductor of heat.
The metals which are the worst conductors of heat, are nearly in the same pro-
portion the worst conductors of electricity ; and all other substances appear to
be comparatively very much worse conductors of electricity than of heat ; stones,
glass, dry wood. and so on, being, as compared with metals, nearly perfect non-
conductors of electricity, and yet possessing very considerable conducting powers
for heat. It is true, we may, as has been shown above, diminish without limit
the waste of energy by frictional generation of heat in the circuit, by using an
engine to do work and react against the thermal electro-motive force ; but, as we
have also seen, this can only be done by keeping the strength of the current very
small compared with what it would be if allowed to waste all the energy of the
electro-motive force on the frictional generation of heat; and it therefore re-
quires a very slow use of the thermo-electric action. At the same time, it does
not in any degree restrain the dissipation of energy by conduction, which is
always going on, and which will therefore bear an even much greater proportion
to the thermal agency electrically spent than in the case in which the latter was
supposed to be unrestrained by the operation of the engine. By far the greater
part of the heat taken in at all, then, in any thermo-electric arrangement, is essen-
tially dissipated, and there would be no violation of the great natural law
expressed in Carnort’s principle, if the small part of the whole action, which is
reversible, gave a different, even an enormously different, and either a greater or
-a less, proportion of heat converted into work to heat taken in, than that law

requires in all completely reversible processes. Still, the reversible part of the

agency, in the thermo-electric circumstances we have supposed, is in itself so per-

fect, that it appears in the highest degree probable it may be found to fulfil inde-

pendently the same conditions as the general law would impose on it if it took

place unaccompanied by any other thermal or thermo-dynamic process.

130 PROFESSOR W. THOMSON ON THE

§§ 107-111. Mathematical expression of the Thermo-dynamic circumstances of
Currents in Linear Conductors.

107. In a heterogeneous metallic conductor the whole heat developed in a
' given time, will consist of a quantity generated frictionally, increased or diminished
by the quantities produced or absorbed in the different parts by action depending
on heterogeneousness of the circuit. The former, according to the law discovered
by JouLE, may be represented by a term By’, in which B denotes a constant de-
pending only on the resistance of the circuit. The latter, being reversible with the
current, may be assumed, at least for infinitely feeble currents, to be, in a given
conductor, proportional simply to the strength of the current; and hence, the
whole quantity of heat evolved in a given time, must be expressible by a term of
the form-— A Y, where A, whether it varies with or.not, has a finite, positive, or
negative value, when ‘¥ is infinitely small. Hence, the whole heat developed in
any portion of a heterogeneous metallic conductor in a unit of time, must be
expressible by the formula
—Ay+By’;

where B is essentially positive, but A may be positive, negative, or zero, according
to the nature of the different parts of the conducting are. It may beassumed, with
great probability, that the quantities A and B are absolutely constant for a given
conductor with its different parts at given constant temperatures, and that when
the temperatures of the different parts of a conductor are kept as nearly constant
as possible with currents of different strengths passing through it, the quantities
A and B can only depend on ‘Y, inasmuch as it may be impossible to prevent the in-
terior parts of the conductor from varying in temperature, and so changing in their
resistance to conduction of electricity, or in their thermo-electric properties. In
the present paper, accordingly, A and B are assumed to depend solely on the nature
and thermal circumstances of the conductor, and to be independent of y; but the
investigations and conclusions would be applicable to cases of action with suf-
ficiently feeble currents, probably to all currents due solely to the thermal electro-
motive force, even if A and B were in reality variable, provided the limiting values
of these quantities for infinitely small values of y be used.

108. Let us consider a conductor of any length and form, but of comparatively
small transverse dimensions, composed of various metals, at different temperatures,
but having portions at its two extremities homogeneous, and at the same temper-
ature. These terminal portions will be denoted by E and E’, and will be called
the principal electrodes, or the electrodes of the principal conductor ; the conductor
itself being called the principal conductor to distinguish it from others, either
joining its extremities or otherwise circumstanced, which we may have to con-
sider again.

DYNAMICAL THEORY OF HEAT. 131

Let an electro-motive force be made to act continuously and uniformly be-
tween these electrodes; as may be done for instance by means of a metallic disc in-
cluded in the circuit touched by electrodes at its centre and a point of its circum-
ference, and made to rotate between the poles of a powerful magnet, an arrange-
ment equivalent to the “engine” spoken of above. Let the amount of this electro-
motive force be denoted by P, to be regarded as positive, when it tends to pro-
duce a current from E through the principal conductor, to E’. Let the absolute
strength of the current, which, in these circumstances, passes through the principal
conductor, be denoted by y, to be considered as positive, if in the direction of P
when positive.

109. Then, Py will be the amount of work done by the electro-motive force in
the unit of time. As this work is spent wholly in keeping up a uniform electric
current in the principal conductor, it must be equal to the mechanical equivalent
of the heat generated, since no other effect is produced by the current. Hence, if
—A7+B7’ be, in accordance with the preceding explanations, the expression for
the heat developed in the conductor in the unit of time by the current y, and if
J, as formerly. denote the mechanical equivalent of the thermal unit, we have

oy Jel opepemtopayis firisi? lye mee) MELI1(3);
which is the expression for the particular circumstances of the first Fundamental
Law of the Dynamical Theory of Heat.
Hence, by dividing by , we have

Peele eh. ea),
from which we deduce
JP ef AN

= — 2 OS igre (537

110. These equations show that, according as P is greater than, equal to, or
less than—J A, the value of Y is positive, zero, or negative ; and that, in any of the
circumstances, the strength of the actual current is just the same as that of the
current which an electro-motive force equal to P+J A would excite in a ho-
mogeneous metallic conductor having J B for the absolute numerical measure of its
galvanic resistance. Hence we conclude :—

(1.) That in all cases in which the value of A is finite, there must be an in-
trinsic electro-motive force in the principal conductor, which would itself produce
a current if the electrodes E, EK’, were put in contact with one another, and which
must be balanced by an equal and opposite force, J A, applied either by means of

a perfect non-conductor, or some electromotor, placed between E and E’,, in order

that there may be electrical equilibrium in the principal conductor ;
And (2.) That J B, which cannot vanish in any case, is the absolute numerical
measure of the galvanic resistance of the principal conductor itself.
It appears, therefore, that the whole theory of thermo-electric force in linear con-
ductors is reduced to a knowledge of all the circumstances on which the value of
VOL. XXI. PART I. 2N

132 PROFESSOR W. THOMSON ON THE

the coefficient A, in the expression— A y+Bv-y? for the heat developed throughout
any given conductor, depends.

110. To express the Second General Law, we must take into account the tem-
peratures of the different localities of the circuit in which heat is evolved or ab-
sorbed, when the current is kept so feeble (by the action of the electro-motive force
P, against the thermo-electric force of the system), as to render the frictional gene-
ration of heat insensible. Denoting then by a, y the heat absorbed in all parts of the
circuit which are at the temperature ¢, by the action of a current of infinitely
small strength Y: so that the term—A ¥y, expressing the whole heat generated not
frictionally throughout the principal conductor in any case, will be the sum of all
such terms with their signs changed, or

A y= 2a;%,
which gives 2@=A . (6) ;
and, if F denote the value of the electro-motive ‘vat seins to tei the thermo-
electric tendency, we have

P= J, Diag A: : “ 3 3 E i (7).
The Second General Law, as expressed above in equation (1), applied to the pre-
sent circumstances, gives immediately,

OY
ie = ; : é : k , (8)

or, since Y is the same for all terms of the sum,
2 =0 a et ae er

111. Of these equations, (7), and (8) from which it is derived, involve no
hypothesis whatever, but merely express the application of a great natural law,—
discovered by JouLE for every case of thermal action whether chemical electrical
or mechanical,—to the electrical circumstances of a solid linear conductor, having
in any way the property of experiencing reverse thermal effects from infinitely
feeble currents in the two directions through it. Equation (9) expresses the
hypothetical application of the Second General Law discussed above in § 106.
The two equations, (7) and (9), express all the information that can be derived
from the General Dynamical Theory of Heat, regarding the special thermal
and electrical energies brought into action by inequalities of temperature, or
by the independent excitation of a current, in a solid linear conductor whether
crystalline or not. The condition that the circuit is to be linear, being merely one
of convenience in the initial treatment of the subject, may of course be removed
by supposing linear conductors to be put together, so as to represent the circum-
stances of a solid conductor of electricity, with any distribution of electric currents
whatever through it; and we may therefore regard these two equations as the
Fundamental Equations of the Mechanical Theory of Thermo-electric Currents.
To work out the theory for crystalline or non-crystalline conductors, it is necessary

DYNAMICAL THEORY OF HEAT. 133

to consider all the conditions which determine the generation or absorption of heat
in different parts of the circuit, whatever be the properties of the metals of which
itis formed. This we may now proceed to do; first for non-crystalline, and after
that for crystalline metals.

§§ 112-124, General Equations of Thermo-electric Currents, in non-crystalline
Linear Conductors.

112. The only reversible thermal effect of electric currents, which experiment
has yet demonstrated, is that which Petrirr has discovered in the passage of elec-
tricity from one metal to another. Besides this, we may conceive that in one
homogeneous metal formed into a conductor of varying section, different thermal
effects may be produced by a current in any part, according as it passes in the
direction in which the section increases, or in the contrary direction; and, with
greater probability, we may suppose that a current in a conductor of one metal
unequally heated, may produce different thermal effects according as it passes
from hot to cold, or from cold to hot. But Macnus has shown, by careful experi-
ments, that no application of heat can sustain a current in a circuit of one homo-
geneous metal, however varying in section; and from this it is easy to conclude,
by equations (7) and (9), that there can be no reversible thermal effect due to the
passage of a current between parts of a homogeneous metallic conductor having dif-
ferent sections. Now, it is clear that no circumstances, except those which have
just been mentioned, can possibly give rise to different thermal effects in any part
of a linear conductor of the same or of different metals, uniformly or non-
uniformly heated, provided none of them be crystalline; and we have, therefore,
at present nothing in the sum 3a, besides the terms depending on the passage
of electricity from one metal to another, which certainly exist, and terms which
may possibly be discovered, depending on its passage from hot to cold, or from
cold to hot in the same metal.

113. Let the principal conductor consist of n different metals; in all n+1 parts,
of which the first and last are of the same metal, and have their terminal por-
tions (which we have called the electrodes E and E’) at the same temperature i Le
Let T,, T,, T,, &c., denote the temperatures of the different junctions in order, and
let n,, ,, u,, &¢., denote the amounts (positive or negative) of heat absorbed at
them respectively by a positive current of unit strength during the unit of time. Let
yo,dt, yo,dt, yo,dt, &c., denote the quantities of heat evolved in each of the
different metals in the unit of time by a current of infinitely small strength, y,
passing from a locality at temperature +d ¢ to a locality at temperature ¢. With-
out hypothesis, but by an obvious analogy, we may call the elements c,, c,, &c., the
specific heats of electricity in the different metals, since they express the quantities
of heat absorbed or evolved by the unit of current electricity in passing from cold
to hot, or from hot to cold, between localities differing by a degree of temperature

134 PROFESSOR W. THOMSON ON THE

in each metal respectively. It is easily shown (as will be seen by the treatment
of the subject to follow immediately) that if the values of o,, ¢,, &c., depend
either on the secizon of the conductor, or on the rate of variation of temperature
along it, or on any other variable differing in different parts of the conductor, except
the temperature, a current might be maintained by the application of heat to a ho-
mogeneous metallic conductor. We may, therefore, at once assume them to be, if
not invariable, absolute functions of the temperature. From this it follows, that

if ¢ denote any function of ¢, the value of the sum, / ptodt, for any conducting

arc of homogeneous metal, depends only on the temperatures of its extremities ;

Za : :
and therefore the parts of the sums Sa, and ae , corresponding to the successive

metals in the principal conductor, are respectively

T, T, Tr Th
-f g, dt, -[ o, dt, woe of c,d t, -f o,dt,
T T, Tr Ty

1

7 T Tr Tn
and vad -f dh ie cabs ey Gn dt, =f Cad te:
CAEN AU Tt Tr t Lt t

Ty Ty Tr-1 Tr
BJ { m1, +m, + Asis +o ff a at—f a,dt—-—[ oud t— ff zat} “> (ae)
8 T; Ey e

ih Tt T'n— 1 Tn
i ke Tn 4A 00; a Lo -f On ah C,
Sees eS) ere wis See ait SiS ae = =a —.déi=0..... Cam
ee T, Jp, ¢ 7, ¢ Tr t T, ¢ (

which are the fundamental equations of thermo-electricity in non-crystalline con-
ductors. In these, along with the equation

which shows the strength of the current actually sustained in the conductor when
an independent electro-motive force, P, is applied between the principal electrodes
K, E’, we have a full expression of the most general circumstances of thermo-
electric currents in linear conductors of non-crystalline metals.

114. The special qualities of the metals of a thermo-electric circuit must be
investigated experimentally before we can fix the values of n,, u,, &c. and
o,, o, &¢c., for any particular case. The relation between these quantities
expressed in the general equation (11), having, as we have seen, a very high
degree of probability, not merely as an approximate law, but as an essential
truth, may be used as a guide, but must be held provisionally until we have suf-
ficient experimental evidence in its favour. The first fundamental equation (10)
admits of no doubt whatever in its universal application, and we shall see (j 123
below) that it leads to most remarkable conclusions from known experimental
facts.

DYNAMICAL THEORY OF HEAT. 135

The general principles are most conveniently applied by restricting the num-
ber of metals referred to in the general equations to two; a case which we accord-
ingly proceed to consider.

115. Let the principal conductor consist of two metals, one constituting the
middle, and the other the two terminal portions. Let the junctions of these por-
tions next the terminals E, E’ be denoted by A, A’ respectively, and let their tem-
peratures be T, T’. Let also n(T),—1 (T’) be the quantities of heat absorbed at
them per second by a current of unit strength. We should have

m(T)=n(T"),

if the temperatures were equal, since the PeLtT1eErR phenomenon consists, as we
hhaye seen, of equal quantities of heat evolved or absorbed, according to the
direction of a current crossing the junction of two different metals; and if these
quantities be not actually equal, we may consider them as particular values of a
function 1 of the temperature, which depends on the particular relative thermo-
electric quality of the two metals. Accordingly, the preceding notation is reduced
ieee Pt T", | ,=1 (2), 0,——1m(T);, and we have

7, 7, T, v
ah. oats fe o,dt+f a (o,-¢,) dt,
T, 7, T, 1

and similarly for the integral involvin L . Hence the general equations become
‘ yi 8 8; g q

fy
Pas {n(t)—n(T) +f (@,-2,)at} eer mere) «FE ae
D T
oe is Se MAME ntlichncssa oni casing hg ED

If in the latter equation we substitute ¢ for T, and differentiate with reference to
this variable, we have, as an equivalent equation,

a(+) o,—6
172 : 4 r i i i SD
pra emigas =" oe?
int @/ at
or ima Viet tT ale : 3 : oy CEG)

This last equation leads to a remarkably simple expression for the electro-motive
force of a thermo-electric pair, solely in the terms of the Prttier evolution of
heat at any temperature intermediate between the temperatures of its junctions;
for we have only to eliminate by means of it (¢,—«¢,) from (13), to find

dy
P= f 1) dd dc MaMa el a i ne EC
na

116. Let us first apply these equations to the case of a thermo-electric pair,

VOL. XXI. PART I. 20

136 PROFESSOR W. THOMSON ON THE

with the two junctions kept at temperatures differing by an infinitely small
amount 7. In this case we have

n(T)-n(1%) =42 r,

vi (o,-—¢,) dt=(6,—46,) 7;
and equation (13) becomes
Pas {Ts 7 ey pee 4 ee
' If we make use of (16) in this, we have
FaJ> Ton en seiin. Beer ta

The first of these expressions for the electro-motive force involves no hypothesis,
but only the general principle of equivalence of heat and work. Its agreement
with any experimental results is only to be looked on as a verification of the ac-
curacy of the experiments, and can add nothing to the certainty of the part of
the theory from which it is deduced. On the other hand, it would be extremely
important to test the second expression (18) by direct experiment, and so confirm
or correct the only doubtful part of the theory. The way to do so would be to de-
termine, in absolute measure, the electro-motive force, F, due to a small difference
of temperature, 7, in any thermo-electric pair, and to determine, in known ther-
mal units, the amount of the PEttiEr effect at a junction of the two metals, with
a current of strength measured in electro-dynamic units, as we should then, by
these determinations, be able to evaluate from direct experiments the values of
the two members separately which appear equated in (18). As yet no observa-
tions have been made which lead, directly or indirectly, to the evaluation of the
second member of (18) in any case; but I hope before long to succeed in carry-
ing out a plan I have formed for this object. Neither have any observations been
made yet, which give in any case a determination of the first member; but they
may easily be accomplished by any person who possesses a conductor of which
the resistance has been determined in absolute measure. Mr Jour having kindly
put me in possession of the silver wire on which his observations of the electrical
generation of heat, in 1845, were made with currents measured by a tangent gal-
vanometer used by him about the same time in experimenting on the electrolysis
of sulphate of copper and sulphate of zinc, I hope to be able to complete the test
of the theoretical result without difficulty, in any case in which I may succeed
in determining the amount of the PELTIER thermal effect.

117. In the mean time, it is interesting to form an estimate, however rough,
of the absolute values of the thermo-electric elements, in any case in which ob-
servations that have been made afford, directly or indirectly, the requisite data.
This I have done for copper and bismuth, and copper and iron, in the manner

DYNAMICAL THEORY OF HEAT. 137

shown in the following explanation; which was communicated in full to the
Royal Society, when the theory was first brought forward in 1851, although only
the part inclosed in double quotation marks was printed in the Proceedings.
Example 1. Copper and Bismuth.—<« ‘ Failing direct data, the absolute value
of the electro-motive force in an element of copper and bismuth, with its two
junctions kept at the temperatures 0° and 100° Cent., may be estimated indirectly
from PovtLuer’s comparison of the strength of the current it sends through a
copper wire 20 metres long and 1 millimetre in diameter, with the strength of a
current decomposing water at an observed rate; by means of the determinations
by Wezer, and others, of the specific resistance of copper and the electro-chemical
equivalent of water, in absolute units. Thespecific resistances of different spe-
cimens of copper having been found to differ considerably from one another, it is
impossible, without experiments on the individual wire used by M. PourLiet, to
determine with much accuracy the absolute resistance of his circuit; but the
author has estimated it on the hypothesis that the specific resistance of its sub-
stance is 2} British units. Taking -02 as the electro-chemical equivalent of water
in British absolute units, the author has thus found 16,300 as the electro-motive
force of an element of copper and bismuth, with the two junctions at 0° and 100°
respectively. About 154 of such elements would be required to produce the
same electro-motive force as a single cell of DANIELL’s—if, in DANIELL’s battery,
the whole chemical action were electrically efficient.* A battery of 1000 copper
and bismuth elements, with the two sets of junctions at 0° and 100° Cent., em-
ployed to work a galvanic engine, if the resistance in the whole circuit be equi-
valent to that of a copper wire of about 100 feet long and about one-eighth of an
inch in diameter, and if the engine be allowed to move at such a rate as by in-
ductive reaction to diminish the strength of the current to the half of what it is
when the engine is at rest, would produce mechanical effect at the rate of about
one-fifth of a horse-power. The electro-motive force of a copper and bismuth ele-
ment, with its two junctions at 0° and 1°, being found by PourtteT to be about
qooth of the electro-motive force when the junctions are at 0° and 100, must be
about 163. The value of 0,’” [2. ¢., in terms of the notation now used, m (273°7),
or the value of n (¢), for the freezing point| “<‘ for copper and bismuth, or the
quantity of heat absorbed in a second of time by a current of unit strength in

* M, Jutes Reenavtp has since found experimentally, that 165 copper- bismuth elements balance
the electro-motive force of a single cell of Danrett’s (See Comptes Rendus, Jan. 9, 1854, or Biblio-
théque Univ. de Genéve, March 1854), a result agreeing with the estimate quoted in the text, more
closely than the uncertainty and indirectness of the data on which that estimate was founded would
have justified us in expecting. The comparison of course affords no test of the thermo-electric theory ;
and only shows that, as far as the observations of Wreper, and others alluded to, render Povurtizt’s
available for determining the absolute electro-motive force of a copper-bismuth element, the absolute
electro-motive force of a single cell of Dantet1’s, obtained by multiplying it by the number found by
M. Reenavp, agrees with that which I first gave on the hypothesis of all the chemical action being
electrically efficient (Phil. Mag., Dec. 1851), and so confirms this hypothesis.

138 PROFESSOR W. THOMSON ON THE

passing from bismuth to copper, when the temperature is kept at 0° Cent. must
therefore be ieee? or very nearly equal to the quantity required to raise the
temperature of a grain of water from 0° to 1° Cent.’”

119. Example 2. Copper and Iron.—* By directing the electro-motive force of
one copper and bismuth element against that of a thermo-electric battery of a
variable number of copper and iron wire elements in one circuit, I have found,
by a galvanometer included in the same circuit, that when the range of tempe-
rature in all the thermo-electric elements is the same, and not very far at either
limit from the freezing point of water, the current passes in the direction of the
copper-bismuth agency when only three, and in the contrary direction when four
or more, of the copper-iron elements are opposed to it. Hence the electro-motive
force of a copper-bismuth element is between three and four times that of a copper-
iron element with the same range of temperature, a little above the freezing point
of water. The electro-motive force of a copper-iron element, with its two junc-
tions at 0° and 1° Cent. respectively, must therefore be something greater than
one-fourth of the number found above for copper-bismuth with the same range of
temperature, that is, something more than 40 British absolute units, and we may
consequently represent it by mx 40, where m>1. We have then by the equation
expressing the application of Carnor’s principle, [ equation (19) of § 116.],

J
0) B = 0) 2713-7 =m x 40,
whence* ©,=fmnearly . ; : : ; ; . i@r

“‘ Now, by the principle of mechanical effect, we have

fy 280
Ras (if 3dt—e,) ;
0

if F,”°° denote the electro-motive force of a copper-iron element, of which the two
junctions are respectively 0° and 280° Cent., and $3 d#, the quantity of heat absorbed
per second by a current of unit strength, in passing in copper from a locality at
temperature ¢ to a locality at ¢+d¢, and in iron from a locality at t+dt to a
locality at ¢; since the PELTIER generation of heat between copper and iron at
their neutral point, 280°, vanishes;{ and therefore the only absorption of heat is
that due to the electric convection expressed by / 3d¢; while there is evolution of

* The value of J now used being 32:2 x 1390=44,758, which is the equivalent of the unit of
heat in “ absolute units” of work. The “absolute unit of force’? on which this unit of work is
founded, and which is generally used in magnetic and electro-magnetic expressions, is the force which
acting on the unit of matter (one grain) during the unit of time (one second), generates a unit of
velocity (one foot per second). The “absolute unit of work” is the work done by the absolute unit
of force in acting through the unit of space (one foot).

+ That is, if 3 denote the algebraic excess of the specific heat of electricity in copper, above the
specific heat of elegtricity in iron, according to the terms more recently introduced.

t See § 123, below. Instead of 240°, conjectured from Rxecnavutt’s observation when these
details were first published, 280° is now taken as a closer approximation to the neutral point of copper
and iron.

DYNAMICAL THEORY OF HEAT. 139

heat amounting to @, at the cold junction, and of mechanical effect by the current
amounting to F units of work. If we estimate the value of F,”*° as half what it
would be were the electro-motive force the same for all equal differences of
temperature as for small differences near the freezing point,* that is, if we take
F,28°=1 x 40m x 280, the preceding equation becomes —

280
140 xm x 40=J ( ‘7 Sat —@, ).
aa)
But we found mx40= pe.

280 140 140 3
Hence va 3 dt = 0, (1+ 3") = 0, (1 ono) = @x5 NEAL, wench ia).

80
gps 9 dt =mx 3 : : ; i ‘ 5 wry hens

results, of which (?) shows how the difference of the aggregate amount of the theo-
retically indicated convective effect in the two metals is related to the PELTIER
effect at the cold junction; and (c) shows that its absolute value is rather more
than one-third of a thermal unit per second per unit strength of current.

120. If the specific heats of current electricity either vanished or were equal
in the different metals, we should have, by (15) and (16),

or, according to (a),

> = constant { 4 : j ’ ~ 0),

and F=J(0-T) Scents aricuinagn gob,

or, the Peitier thermal effect at a junction of two metals would be proportional
to the absolute temperature at which it takes place, and the electro-motive force
in a circuit of any two metals would vary in the simple ratio of the difference of
temperature on the new absolute scale between their junctions.| Whatever
thermometric system be followed, the second of these conclusions would require
the same law of variation of electro-motive force with the temperatures of the
junctions, in every pair of metals used as a thermo-electric element.

121. Before the existence of a convective effect of electricity in an unequally
heated metal had even been conjectured, I arrived at the preceding conclusions by
a theory in which the PEttier effect was taken as the only thermal effect reversible
with the current in a thermo-electric circuit, and found them at variance with

* See § 122, below.

+ When the Theory was first communicated to the Royal Society, I stated these conclusions with
reference to temperature by the air thermometer, and therefore in terms of Carno7’s absolute function
of the temperature, not simply as now in terms of absolute temperature. At the same time, I gave as
consequences of Mayer’s hypothesis, the same statement in terms of air thermometer temperatures,
as is now made absolutely. See Proceedings, Dec. 15, 1851; or Philosophical Magazine, June 1852,
p. 532.

VOL. XXI. PART I. Qp *

140 PROFESSOR W. THOMSON ON THE

known facts which show remarkably different laws of electro-motive force in ther-
mo-electric pairs of different metals. I therefore inferred, that besides the PeLTmer
effect there must be other reversible thermal effects; and I showed that these can
be due to no other cause than the inequalities of temperature in single metals in
the circuit. A convective effect of electricity in an unequally heated conductor of
one metal was thus first demonstrated by theoretical reasoning ; but only the differ-
ence of the amount of this effect produced by currents of equal strength in differ-
ent metals, not its quality or its absolute value in any one metal, could be inferred
from the data of thermo-electric force alone. The case of a thermo-electric circuit
of copper and iron, being that which first forced on me the conclusion that an
electric current must produce different effects according as it passes from hot to
cold, or from cold to hot, in an unequally heated metal, was taken as an example
in my first communication of the Theory to this Sociéty;* and the two metals,
copper and iron, were made the subjects of a consequent experimental investiga-
tion, to ascertain the quality of the anticipated property in each of them sepa--
rately. The application of the general reasoning to this particular case, and the
answers which I have derived by experiment to the question which it raises, are
described in the following extract of a Report communicated to the Royal Society
of London, March 31, and published in the Proceedings, May, of the present year :—

122. “ BecQuEREL discovered that if one junction of copper and iron, in a circuit
of the two metals, be kept at an ordinary atmospheric temperature, while the other.
is raised gradually, a current first sets from copper to iron through the hot Junc-
tion, increasing in strength only as long as the temperature is below about 300°
Cent.; and becoming feebler with farther elevation of temperature until it ceases,
and a current actually sets in the contrary direction when a high red heat is at-
tained.+ Many experimenters have professed themselves unable to verify this
extraordinary discovery ; but the description which M. BecquERe. gives of his
experiments leaves no room for the doubts which some have thrown upon his
conclusion, and establishes the thermo-electric inversion between iron and copper,
not as a singular case (extraordinary and unexpected as it appeared), but as a
phenomenon to be looked for between any two metals, when tried through a suf-
ficient range of temperatures. M. Recnav.r has verified M. BecquErEt’s con-
clusion so far, in finding that the strength of a current in a circuit of copper and
iron wire did not increase sensibly for elevations of temperature above 240° Cent.,
and began to diminish when the temperature considerably exceeded this limit;

* See Proceedings, R. 8. E., Dec. 15, 1851.

} Since this was written, I have found that thermo-electric inversions between copper and an
alloy of antimony and bismuth, and between silver and the same alloy, precisely analogous to that
between copper and iron more recently discovered by M. BecquerEt, were discovered as early as
1823, by Professor Cummine of Cambridge, shortly after the thermo-electricity of metals was first
brought to light by Sersecx. These, with other experiments, leading to important results, especially

as to the order of metals and metallic compounds in the thermo-electric series, are described in the
Cambridge Transactions for 1823, and in Professor Cummine’s Treatise on Hlectro-dynamics.

DYNAMICAL THEORY OF HEAT. 141

but the actual inversion observed by M. BecquEREt is required to show that the
diminution of strength in the current is due to a real falling off in the electro-
motive force, and not to the increased resistance known to be produced by an
elevation of temperature.

123. “From BrecQueREL’s discovery it follows that, for temperatures below a
certain limit, which, for particular specimens of copper and iron wire, I have ascer-
tained, by a mode of experimenting described below, to be 280° Cent., copper is on
the negative side of iron in the thermo-electric series ; on the positive side for higher
temperatures; and at the limiting temperature these two metals are thermo-
electrically neutral to one another. It follows, according to the general mecha-
nical theory* of thermo-electric currents, referred to above, that electricity pass-
ing from copper to iron causes the absorption or the evolution of heat according
as the temperature of the metals is below or above the neutral point ; but neither
absorption nor evolution of heat, if the temperature be precisely that of neutrality ;
(a conclusion which I have already partially verified by experiment). Hence, if in
a circuit of copper and iron, one junction be kept about 280”, that is, at the neutral
temperature, and the other at any lower temperature, a thermo-electric current
will set from copper to iron through the hot, and from iron to copper through the
cold, junction; causing the evolution of heat in the latter, and the raising of
weights, too, if it be employed to work an electro-magnetic engine, but not causing
the absorption of any heat at the hot junction. Hence there must be an absorp-
tion of heat at some part or parts of the circuit consisting solely of one metal or
of the other, to an amount equivalent to the heat evolved at the cold junction,
together with the thermal value of any mechanical effects produced on other
parts of the circuit. The locality of this absorption can only be where the tem-
peratures of the single metals are non-uniform, since the thermal effect of a cur-
rent in any homogeneous uniformly-heated conductor is always an evolution of

* This is the only part of the theoretical reasoning as first given, which depended on the appli-
cation of Carnot’s principle, and consequently, is the only part capable of being objected to as un-
certain. AJ] doubt would be removed by an experimental verification of the stated Pstrizr effects for
copper and iron, at the different temperatures, such as I hope very soon to have completed. In the
meantime, instead of the theoretical reasoning, we may, if it is preferred, use an ample foundation of
analogy to conclude that heat is absorbed at the hotter junction, and evolved at the colder, by the
actual thermo-electric current in every case of a circuit of two metals, with their junctions differing
but little in temperature., For it was found by Perrier himself, that currents from bismuth to copper,
from copper to antimony, from zinc to iron, from copper to iron, and from platinum to iron, cause
absorption, and the reverse current in each case, evolution of heat; experimental conclusions, with
which I was not acquainted when I first published the Theory. Very soon after I found, myself,
by experiment, that copper and iron at ordinary atmospheric temperatures, exhibit the anticipated
thermal phenomenon ; and corresponding experimental results have been obtained still more recently
in the cases of bismuth and copper, copper and antimony, copper and iron, German silver and iron, by
FRANKENHEIM. (PoccEnporrr’s Annalen, Feb. 1854); in every case, the current which would be
produced by heating one junction a little, being that which in the same junction causes an absorption
of heat. If we consider the induction sufficient to establish this as a universal law in thermo-elec-
tricity, the reasoning in the text becomes independent of any hypothesis to which objections can pos-
sibly be raised.

142 PROFESSOR W. THOMSON ON THE

heat. Hence there must be on the whole absorption of heat caused by the current
passing from cold to hot in copper, and from hot to cold in iron. When a current
is forced through the circuit against the thermo-electric force, the same reasoning
establishes an evolution of heat to an amount equivalent to the sum of the heat
that would be then taken in at the cold junction, and the value in heat of the
energy spent by the agency (chemical, or of any other kind) by which the electro-
motive force is applied. The aggregate reversible thermal effect, thus demon-
strated to exist in the unequally-heated portions of the two metals, might be
produced in one of the metals alone, or (as appears more natural to suppose) it
may be the sum or difference of effects experienced by each. Adopting, as a matter
of form, the latter supposition, without excluding the former possibility, we may
assert that either there is absorption of heat by the current passing from hot to
cold in the copper, and evolution to a less extent, in the iron of the same circuit ;
or there is absorption of heat produced by the current from hot to cold in the
iron, and evolution of heat to a less amount in the copper; or there must be
absorption of heat in each metal: with the reverse effect in each case, when the
current is reversed. The reversible effect in a single metal of non-uniform tem-
perature may be called a convection of heat; and, to avoid circumlocution, I shall
express it, that the vitreous electricity carries heat with it, or that the specific
heat of vitreous electricity is positive, when this convection is in the nominal
‘ direction of the current ; and I shall apply the same expressions to ‘ resinous
electricity,’ when the convection is against the nominal direction of the current.
It is established, then, that one or other of the following three hypotheses must
be true :—

124. “ Vitreous electricity carries heat with it in an unequally heated con-
ductor, whether of copper or iron ; but more in copper than in iron:

«Or, resinous electricity carries heat with it in an unequally heated conductor,
whether of copper or iron; but more in iron than in copper:

‘“‘ Or, vitreous electricity carries heat with it in an unequally heated conductor
of copper, and resinous electricity carries heat with it in an unequally heated

‘conductor of iron.

125. “ Immediately after communicating this theory to the Royal Society of
Edinburgh, I commenced trying to ascertain by experiment which of the three hy-
potheses is the truth, as Theory, with only thermo-electric data, could not decide
between them. I had a slight bias in favour of the first rather than the second,
in consequence of the positiveness which, after FRaNKLIN, we habitually attri-
bute to the vitreous electricity, and a very strong feeling of the improbability of
the third. With the able and persevering exertions of my assistant, Mr M‘Far-
LANE, applied to the construction of various forms of apparatus, and to assist me
in conducting experiments, the research has been carried on with little intermis-
sion for more than two years. Mr Ropert Davipson, Mr Cuaries A. Smiru, and

DYNAMICAL THEORY OF HEAT. 143

other friends, have also given much valuable assistance during a great part of
this time, in the different experimental investigations, of which the results are
now laid before the Royal Society.

126. “ Only nugatory results were obtained until recently, from multiplied and
varied experiments both on copper and iron conductors; but the theoretical anti-
cipation was of such a nature, that no want of experimental evidence could in-
fluence my conviction of its truth. About four months ago, by means of a new
form of apparatus, I ascertained that resinous electricity carries heat with it in an
unequally heated iron conductor. A similar equally sensitive arrangement showed
no result for copper. The second hypothesis might then have been expected to
hold; but to ascertain the truth with certainty, I have continued ever since get-
ting an experiment on copper nearly every week, with more and more sensitive
arrangements; and at last, in two experiments, I have made out with certainty,
that vitreous electricity carries heat with it in an unequally heated copper con-
ductor.

« The third hypothesis is thus established ; a most unexpected conclusion, I
am willing to confess.

‘ [ intend to continue the research; and hope not only to ascertain the nature
of the thermal effects in other metals, but to determine its amount in absolute
measure in the most important cases, and to find how it varies, if at all, with the
temperature; that is, to determine the character (positive or negative) and the
value of the specific heat, (varying or not with the temperature, ) of the unit of cur-
rent electricity in various metals.”

127. The relations .

i Bes EO) and Fas f 2a Baca ash ag Seek)
established above, “‘ show how important it is towards the special object of
determining the specific heats of electricity in metals, to investigate the law of
electro-motive force in various cases, and to determine the thermal effect of elec-
tricity in passing from one metal to another at various temperatures. Both of
these objects of research are therefore included in the general investigation of the
subject.

128. “ The only progress I have as yet made in the last-mentioned branch of the
inquiry, has been to demonstrate experimentally, that there is a cooling or heating
effect produced by a current between copper and iron, at an ordinary atmospheric
temperature, according as it passes from copper to iron, or from iron to copper,
in verification of a theoretical conclusion mentioned above; but I intend shortly
to extend the verification of theory to a demonstration, that reverse effects take
place between those metals, at any temperature above their neutral point of about
280° Cent.; and I hope also to be able to make determinations in absolute

VOL, k Xi, PART I. 2Q

144 PROFESSOR W. THOMSON ON THE

measure of the amount of the PeLti&rR effect for a given strength of current be-
tween various pairs of metals.

129. “ With reference to laws of Clecivesteiee force in various cases, I have
commenced by determining the order of several specimens of metals in the thermo-
electric series, and have ascertained some very curious facts regarding varieties
in this series, which exist at different temperatures. In this I have only followed
BecquEReE’s remarkable discovery, from which I had been led to the reasoning
and experimental investigation regarding copper and iron described above. My
way of experimenting has been, to raise the temperature first of one junction as
far as the circumstances admit, keeping the other cold, and then to raise the
temperature of the other gradually, and watch the indications of a galvanometer
during the whole process. When an inversion of the current is noticed, the
changing temperature is brought back till the galvanometer shows no current ;
and then (by a process quite analogous to that followed by Mr Jouns, and Dr
Lyon PLAYFAIR, in ascertaining the temperature at which water is of maximum
density), the temperatures of the two junctions are approximated, the galvano-
meter always being kept as near zero as possible. When the difference between
any two temperatures on each side of the neutral point which give no current is
not very great, their arithmetical mean will be the neutral temperature. A regular
deviation of the mean temperature from the true neutral temperature is to be
looked for with wide ranges, and a determination of it would show the law accord-
ing to which the difference of the specific heat of electricity in the two metals
varies with the temperatures ; but I have not even as yet ascertained with certainty
the existence of such a deviation in any particular case. The following is a summary
of the principal results I have already obtained in this department of the subject.

130. “ The metals tried being—three platinum wires (P, the thickest, P, the
thinnest, and P, of intermediate thickness), brass wires (B), a lead wire (L’), slips of
sheet-lead (L), copper wires (C), and iron-wire (I) ; I find that the specimens experi-
mented on stand thermo-electrically, at different temperatures, in the orders shown
in the following table, and explained in the heading by reference to bismuth and
antimony, or to the terms “negative” and “ positive,” as often used :—.

Tempers Bismuth
ture

Centigrade.

Antimony
“ Necative.” 6c Crh ee)
egative. Positive.

—20 12 c By SOOO HON POR EAU! Re Se
0 P, r P, 6 Prien Marten Tita
37 Past tala: BASEL ea ata Cicy Bntensedant Ii eshte
64 Pan thik ae. P, Bd he el OP Mn eine Ty att ateete

130 Davicer etait Pi vtncancasglat eee TRI dlege 4 | ee pee

140 cece keer Rt Se ere Be ERLE (Ci. Th ea el

280 ee eae Pee cele P, RI he

300 ee eee Epa Ap Dig alpet Se C

DYNAMICAL THEORY OF HEAT. 145

_ It must be added, by way of explanation, that the bracket enclosing the symbols
of any two of the metallic specimens indicates that they are neutral to one another
at the corresponding temperature; and the arrow-head below one of them shows
the direction in which it is changing its place with reference to the other, in the
series, as the temperature is raised. When there is any doubt as to a position as
shown in the table, the symbol of the metal is a small letter instead of a capital.

131. “ The rapidity with which copper changes its place among some of the
metals (the platinums and iron) is very remarkable. Brass also changes its
place in the same direction, possibly no less rapidly than copper; and lead changes
its place also in the same direction, but certainly less rapidly than brass, which,
after passing the thick platinum wire P, at 130° Cent., passes the lead at 140°,
the lead itself having probably. passed the thick platinum at some temperature a
little below 130° [at 121, as I afterwards found]. The conclusion, as regards spe-
cific heats of electricity in the different metals, from the equation expressing
thermo-electric force given above, is,—that the specific heat of vitreous electricity
is greater in each metal passing another from left to right in the series, as the
temperature rises, than in the metal it passes; thus in particular —

132. “ The specific heat of vitreous electricity is greater in copper than in plati-
num or in iron; greater in brass than in platinum or in lead ; and greater in lead
than in platinum. ;

133. “It is probable enough, from the results regarding iron and copper men-
tioned above, that the specific heat of vitreous electricity is positive in brass; and
very small positive or else negative in platinum, perhaps about the same as in iron.
It will not be difficult to test these speculations either by direct experiments on
the convective effects of electric currents in the different metals, or by compara-
tive measurements of thermo-electric forces for various temperatures in circuits
of the metals, and I trust to be able to do so before long.”

§§ 134, 135. Inserted September 15, 1854.

134. A continuation of the experiments has shown many remarkable varia-
tions of order in the thermo-electric series. The following table exhibits the re-
sults of observations to determine neutral points for different pairs of metals:
the number at the head of each column being the temperature centigrade at which
the two metals written below it are thermo-electrically neutral to one another;
and the lower metal in each column being that which passes the other from bis-
muth towards antimony, as the temperature rises.

=—14° Cent.| —12°2 | —1-°5| 8°2 36° 38° 44° 44° 162°°5 237° | 280°

P, By ey, Br 1 1 P,- | Lead |P, Ey 1 Pr Tron Iron | Iron
' Brass. Cadmium. | Silver.) Zine. | Lead.| Brass.| Tin. | Brass. |Copper| Brass. | Lead. | Tin. | Cadmium. | Silver./Copper
|

I also found that brass becomes neutral to copper, and copper becomes neutral to
silver, at some high temperatures, estimated at from 800° to 1400° Cent., in the

146 PROFESSOR W. THOMSON ON THE

former case, and from 700° to 1000° in the latter, being a little below the melting
point of silver. The following diagram exhibits the results graphically, constructed
on the principle of drawing a line through the letters corresponding to any one of
the metallic specimens in a table such as that of § 130, and arranging the spaces
so that each line shall be as nearly straight as possible, if not exactly so.

30° o° 50° 100° 150
mare

Iron ay aria 30
gi ;
oot
Pi
Pi Lan
VN 1

‘ peed
The orders of the metals in the thermo-electric series, at different temperatures, are shown by

the points in which the vertical lines through the numbers expressed by the temperatures centigrade
are cut by the horizontal and oblique lines named for the different metallic specimens.

or

s\_\
A

ie A SSN ee
ry
EN
=\
: PS
aaa
eS
rer
Pers

Le aia
Lea

Explanation of Thermo-electric Diagram.

The object to be aimed at in perfecting a thermo-electric diagram, and per-
haps approximately attained to (conjecturally) in the preceding, is to make the
ordinates of the lines (which will, in general, be curves) corresponding to the
different metallic specimens, be exactly proportional to their thermo-electric
powers,* with reference to a standard metal (P, in the actual diagram).

135. Judging by the eye from the diagram, as regards the convective agency
of electricity in unequally heated conductors, I infer that the different metals are
probably to be ranked as follows, in order of the values of the specific heat of

electricity in them.
Speciic Heat of Vitreous Electricity :—

In Cadmium, : sae, we . Positive.
» Brass,
» Copper, j : .
is {eee} “ ‘ ‘ . Positive, zero, or negative.
» . elatingm. > s : . Probably negative.
Tron, : Negative.

Zinc probably ‘stands high, certainly above platinum.
* See § 140, below.

DYNAMICAL THEORY OF HEAT. 147

136. A very close analogy subsists between the thermo-dynamical circum-
stances of an electrical current in a circuit of two metals, and those of a fluid
circulating in a closed rectangular tube, consisting of two vertical branches con-
nected by two horizontal branches. Thus if, by the application of electro-motive
force in one case, or by the action of pistons in the other, a current be instituted,
and if, at the same time, the temperature be kept uniform throughout the circuit,
heat will be evolved and absorbed at the two junctions respectively in the former
case, and heat will be evolved in one and absorbed in the other of vertical branches
of the tube in the latter case, in consequence of the variations of pressure expe-
rienced by the fluid in moving through those parts of the circuit. If the temperature
of one junction of the electrical circuit be raised above that of the other, and if the
temperature of one vertical branch of the tube containing fluid be raised above that
of the other, a current will in each case be occasioned, without any other motive
appliance. Ifthe current be directed to do work with all its energy, by means of
an engine in each case, there will be a conversion of heat into mechanical effect,
with perfectly analogous relations as to absorption and evolution of heat in dif-
ferent parts of the circuit, provided the engine worked by the fluid current be
arranged to pass the fluid through it without variation of temperature from or to
either of the vertical branches of the tube. If, and c, denote the specific heat
of unity of mass of the fluid, under the constant pressures at which it exists in
the lower and upper horizontal branches of the tube in the second case; 1(T),
m1(T’) the quantities of heat evolved and absorbed respectively by the passage of
a unit mass of fluid through the two vertical branches kept at the respective
temperatures T, T’; and if F denote the work done by a unit mass of the fluid in
passing through the engine; the fundamental equations obtained above, with re-
ference to the thermo-electric circumstances, may be at once written down for
the case of the ordinary fluid, as the expression of the two fundamental laws of
the Dynamical Theory of Heat, both of which are applicable to this case, without
any uncertainty such as that shown to be conceivable as regards the application
of the second law to the case of a thermo-electric current. The two equations thus
obtained are equivalent to the two general equations given, in §§ 20 and 21 of the
First Part of this series of papers, as the expressions of the fundamental laws of
the Dynamical Theory of Heat applied to the elasticity and expansive properties
of fluids. In fact, when we suppose the ranges of both temperature and pressure

in the circulating fluid to be infinitely small, the equation F=J uf ; * dt, reduced
~

to the notation formerly used, and modified by changing the independent va-
riables from (é, 7») to (d, 7), becomes

M=1—2

VOL. XXI. PART I. 2

148 PROFESSOR W. THOMSON ON THE
eve aicb yt 3 bt: eel in A CET
which is the same as (3) of § 21; and a combination of this with hi (7) =

i
: dM _dN _1 dp
ee di dv J dt’

which is identical with (2) of § 20. It appears, then, that the consideration of
the case of fluid motion here brought forward as analogous to thermo-electric
currents in non-crystalline linear conductors, is sufficient for establishing the ge-
neral thermo-dynamical equations of fluids, and consequently the universal rela-
tions among specific heats, elasticities, and thermal effects of condensation or
rarefaction, derived from them in Part III., are all included in the investigation
at present indicated. Not going into the details of this investigation, because the
former investigation, which is on the whole more convenient, is fully given in
Parts I. and III., I shall merely point out a special application of it to the case
of a liquid which has a temperature of maximum density, as for instance water.
137. In the first place, it is to be remarked, that if the two vertical branches be
kept at temperatures a little above and below the point of maximum density, no
current will be produced ; and therefore if T, denote this temperature, the equa-

tion F = if . dt gives m(T,)=0. Again, if one of the vertical branches be kept at

T,, and the other be kept at a temperature either higher or lower, a current will
T

set, and always in the same direction. Hence wi - dt has the same sign, whether.
Ty

T be greater or less than T,, and consequently m(#) must have contrary signs for
values of ¢ above and below T,: which, by attending to the signs in the general
formulze, we see must be such as to express evolution of heat by the actual current
in the second vertical branch, when its temperature is below, and absorption when
above, T,. As the current in each case ascends in this vertical branch, we conclude
that a slight diminution of pressure causes evolution or absorption of heat, in water,
according as its temperature is below or above that of maximum density; or
conversely,—That when water is suddenly compressed, it becomes colder if ini-
tially below, or warmer if initially above, its temperature of maximum density.
This conclusion from general thermo-dynamic principles was first, so far as I
know, mentioned along with the description of an experiment to prove the lower-
ing of the freezing point of water by pressure, communicated to the Royal So-
ciety in January, 1850.* The quantitative expression for the effect, which was
given in § 50 of Part III., may be derived with ease from the considerations now
brought forward. The other thermo-dynamic equation a + shows that
the specific heat of the water must be greater in the upper horizontal branch

* See Proceedings of that date, or Philosophical Magazine, 1850.

DYNAMICAL THEORY OF HEAT. 149

than in the lower; or that the specific heat of water under constant pressure is
increased by a diminution of the pressure. The same conclusion, and the amount
of the effect, are also implied in equations (18) and (19) of Part II. We may
arrive at it without referring to any of the mathematical formule, merely by an
application of the general principle of mechanical effect, when once the conclu-
sion regarding the thermal effects of condensation or rarefaction is established ;
exactly as the conclusion regarding the specific heats of electricity in copper and
in iron was first arrived at.* For if we suppose one vertical branch to be kept at
the temperature of maximum density (corresponding to the neutral point of the
metals in the corresponding thermo-electric case), and the other at some lower
temperature, a current will set downwards through the former branch, and upwards
through the latter. This current will cause evolution of heat, in consequence of
the expansion of the fluid, in the branch through which it rises, but will cause
neither absorption nor evolution in the other vertical branch, since in it the tem-
perature is that of the maximum density. There will also be heat generated in
various parts by fluid friction. There must then be, on the whole, absorption of
heat in the horizontal branches; because otherwise there would be no source of
energy for the heat constantly evolved to be drawn from. But heat will be evolved
by the fluid in passing in the lower horizontal branch from hot to cold; and there-
fore, exactly to the extent of the heat otherwise evolved, this must be over-com-
pensated by the heat absorbed in the upper horizontal branch by the fluid passing
from cold to hot. On the other hand, if one of the vertical branches be kept above
the temperature of maximum density, and the other at this point, the fluid will
sink in the latter, causing neither absorption nor evolution of heat, and rise in the
former, causing absorption ; and therefore more heat must be evolved by the fluid
passing from hot to cold in the upper horizontal branch than is absorbed by it in
passing from cold to hot in the lower. From either case, we infer that the specific
heat of the water is greater in the upper than in the lower branch. The analogy
with the thermo-electric circumstances of two metals which have a neutral point,
is perfect algebraically in all particulars. The proposition just enunciated corre-
sponds exactly to the conclusion arrived at formerly, that if one metal passes an-
other in the direction from bismuth towards antimony in the thermo-electric scale,
the specific heat of electricity is greater in the former metal than in the latter;
this statement holding algebraically, even in such a case as that of copper and
iron, where the specific heats are of contrary origin in the two metals, although
the existence of such contrary effects is enough to show how difficult it is to con-
ceive the physical circumstances of an electric current as physically analogous to
those of a current of fluid in one direction.

* Proceedings R. 8. E., Dec. 15, 1851, or extract of Proceedings R. S., May 1854, quoted
above, § 124.

150 PROFESSOR W. THOMSON ON THE

§§ 138-140. General Lemma, regarding relative thermo-electric properties of
Metals, and multiple combinations in a Linear Circuit.

138. The general equation (11), investigated above, shows that the aggregate
amount of all the thermal effects produced by a current, or by any system of currents,
in any solid conductor or combination of solid conductors must be zero, vf all the
localities in which they are produced are kept at the same temperature.

Cor. 1. If in any circuit of solid conductors the temperature be uniform from
a point P through all the conducting matter to a point Q, both the aggregate
thermal actions, and the electro-motive force are totally independent of this inter-
mediate matter, whether it be homogeneous or heterogeneous, crystalline or non-
crystalline, linear or solid, and is the same as if P and Q were put in contact. [The
importance of this simple and elementary truth in thermo-electric experiments of
various kinds is very obvious. It appears to have been overlooked by many expe-
rimenters who have scrupulously avoided introducing extraneous matter (as solder)
in making thermo-electric junctions, and who have attempted to explain away
Cummine’s and BecquEREL’s remarkable discovery of thermo-electric inversions,
by referring the phenomena observed to coatings of oxide formed on the metals
at their surfaces of contact. |

Cor. 2. Etre GiB); mae C), Tee My eee, 1 m (Z, A) denote the amounts of
the Pe.trier absorption of heat per unit strength of current per unit of time, at the
successive junctions of a circuit of metals A, B,C, .... Z, A, we must have,

Eh (As bape at (Es G) te ce cee hee + 1 (Z, A) =0.
Thus if the circuit consist of three metals,
mt (A, B) + 1(B, C) + m(C, A) = 0;
from which, since. m (C, A)= — 11 (A, C), we derive
ti (B, C) = 1 (A, C) — 1 (A, B).

139. Now, by (19) above, the electro-motive force in an element of the two

inetals (A, B), tending from B to A through the hot junction, for an infinitely small

difference of temperature 7, and a mean absolute temperature 7, is Sass = B) cas

and so for every other pair of metals. Hence, if ¢ (A,B), ¢ (B, C), &c., denote
the quantities by which the infinitely small range 7 must be multiplied to get the
electro-motive forces of elements composed of successive pairs of the metals in the
same thermal circumstances, we have
Gx(As Beep (ByC) Aa. Aa. + $ (Z, A)=0;
and, for the case of three metals,
(B, C) = (A, C) — > (A, B).

Since the thermo-electric force for any range of temperature is the sum of the
thermo-electric forces for all the infinitely small ranges into which we may divide

DYNAMICAL THEORY OF HEAT. 151

mie
_ the whole range (being, as proved above, equal to 5 ¢ dt), in the case of each ele-
ly

ment, the theorem expressed by these equations is true of the thermo-electric
forces in the single elements for a// ranges of temperature, provided the absolute
temperatures of the hot and cold junctions be the same in the different elements.
The second equation, by successive applications of which the first may be derived,
is the simplest expression of a theorem which was, I believe, first pointed out and
experimentally verified by BecquEREL in researches described in the second volume
of his Traité d’Electricité.

140. For brevity, we shall call what has been denoted by ¢ (B, C) the thermo-
electric relation of the metal B to the metal C; we shall call a certain metal (per-
haps copper or silver) the standard metal; and if A be the standard metal, we
shall call ¢ (A, B) the thermo-electric power of the metal B. The theorem expressed
by the last equation may now be stated‘thus: The thermo-electric relation between
two metals is equal to the difference of their thermo-electric powers ; which is nearly
identical with BecquEREL’s own statement of his theorem.

§§ 141-146. Hlementary Explanations in Electro-cinematics and Electro-mechanics.

141. When we confined our attention to electric currents flowing along linear
conductors, it was only necessary to consider in each case, the whole strength of
the current, and the longitudinal electro-motive force in any part of the circuit,
without taking into account any of the transverse dimensions of the conducting
channel. In what follows, it will be frequently necessary to consider distributions
of currents in various directions through solid conductors, and it is therefore con-
venient at present to notice some elementary properties, and to define various
terms, adapted for specifications of systems of electric currents and electro-motive
forces, distributed in any manner whatever throughout a solid.

142. It is to be remarked, in the first place, that any portion of a solid traversed
by current electricity may be divided, by tubular surfaces coinciding with lines of
electric motion, into an infinite number of channels or conducting arcs, each con-
taining an independent linear current. The strength of a linear current being, as
before, defined to denote the quantity of electricity flowing across any section in
the unit of time, we may now define the intensity of the current, at any point of a
conductor, as the strength of a linear current of infinitely small transverse dimen-
sions through this point, divided by the area of a normal section of its channel. The
elementary proposition of the composition of motions, common to the cinematics
of ordinary fluids and of electricity, shows that the superposition of two systems
of currents in a body gives a resultant system, of which the intensity and direc-
tion at any point are represented by the diagonal of a parallelogram described
upon lines representing the intensity and direction of the component systems

VOL. XXI. PART I. 2s

152 PROFESSOR W. THOMSON ON THE

respectively. Hence we may define the components, along three lines at right
angles to one another, of the intensity of electric current through any point of a
body, as the products of the intensity of the current at that point into the cosines
of the inclination of its direction to those three lines respectively; and we may
regard the specification of a distribution of currents through a body as complete,
when the components, parallel to three fixed rectangular axes of reference, of the
intensity of the current at every point are specified.

143. The term electro-motive force has been applied, in what precedes, con-
sistently with the ordinary usage, to the whole force urging electricity through a
linear conducting are. When a current is sustained through a conducting are, by
energy proceeding from sources belonging entirely to the remainder of the circuit,
the electro-motive force may be considered as applied from without to its extre-
mities ; and in all such cases it may be measured—electro-statically, by determin-
ing in any way the difference of potential between two conducting bodies, insulated
from one another and put in metallic communication with the extremities of the
conducting arc;—or electro-dynamically, by applying to these points the extremities
of another linear conductor, of infinitely greater resistance (practically, for instance,
a long fine wire used as a galvanometer coil), and determining the strength of the
current which it conveys when so applied. These tests may, of course, be regarded
as giving either the amount of the electro-motive force with which the remainder
of the circuit acts on, or the whole of the electro-motive force efficient in, the
passive conducting arc first considered. On the other hand, the electro-motive
force acting in the portion from which the energy proceeds is not itself deter-
mined by such tests, but is equal to the whole electro-motive force of the sources
contained in it, diminished by the reaction of the force which is measured in the
manner just explained. The same tests applied to any two points whatever of a
complete conducting circuit, however the sources of energy are distributed through
it, show simply the electro-motive force acting and reacting between the two
parts into which the circuit might be separated by breaking it at these points.
In some cases, for instance some of thermo-electric action which we shall have to
consider, these tests would give a zero indication to whatever two points of a circuit
through which a current is actually passing they are applied, and would there-
fore show that there is no electric action and reaction between different parts of
the circuit, but that each part contains intrinsically the electro-motive force re-
quired to sustain the current through it at the existing rate. An actual test of
the electro-motive force of sources contained in any part of a linear conductor is
defined, with especial reference to the circumstances of thermo-electricity, in the
following statement :—

144. Der. The actual intrinsic electro-motive force of any part of a linear
conducting circuit is the difference of potential which it produces in two insulated
conductors of a standard metal at one temperature, when its extremities are

DYNAMICAL THEORY OF HEAT. 153

connected with them by conducting arcs of the same metal, and insulated from the
remainder of the circuit.

The electro-motive force so defined may be determined either by stration
by some electro-statical method, the difference of potentials in the two conductors
of standard metal mentioned in the definition; or by measuring the strength of
the current produced in a conducting are of the standard metal of infinitely
ereater resistance than the given conducting arc, applied to connect its extre-
mities, when insulated from the remainder of its own circuit.

145. With reference to the distribution of electro-motive force through a solid,
the following definitions are laid down :—

Der. 1. The intrinsic electro-motive force of a linear conductor at any point
is the actual intrinsic electro-motive force in an infinitely small arc through this
point, divided by its length.

Der. 2. The efficient electro-motive force at any point of a linear conducting
circuit is the sum of the actual intrinsic electro-motive force in an infinitely small
are, and the electro-motive force produced by the remainder of the circuit on its
extremities, divided by its length.

Der. 3. The intrinsic electro-motive force at any point in a solid, in any di-
rection, is the electro-motive force that would be experienced by an infinitely
thin conducting arc of standard metal, applied with its extremities to two points
in a line with this direction, in an infinitely small portion insulated all round
from the rest of the solid, divided by the distance between these points.

Der. 4. The electro-motive force efficient at any point of a solid, in any direc-
tion, is the difference of the electro-motive forces that would be experienced by an
infinitely thin conducting arc of standard metal, with its extremities applied to
two points infinitely near one another in this direction, divided by the distance
between the points, in the two cases separately of the solid being left unchanged,
and of an infinitely small portion of it containing these points being insulated
from the remainder.

146. Principle of the superposition of thermo-electric action. It may be assumed
as an axiom, that each of any number of co-existing systems of electric currents
produces the same reversible thermal effect in any locality as if it existed alone.

§§ 147-155. On Thermo-electric Currents in Linear Conductors of Crystalline
Substance.

147. The general characteristic of crystalline matter is that physical agencies,
having particular directions in the space through which they act, and depending
on particular qualities of the substance occupying that space, take place with
different intensities in different directions, if the substance be crystalline. Sub-
stances not naturally crystalline may have the crystalline characteristic induced
in them by the action of some directional agency, such as mechanical strain or

154 PROFESSOR W. THOMSON ON THE

magnetization; and may be said to be inductively crystalline. Or again, minute ~
fragments of non-crystalline substances may be put together, so as to constitute
solids, which, on a large scale, possess the general characteristic of homogeneous
crystalline substances; and such bodies may be said to possess the crystalline
characteristic by structure, or to be structurally crystalline.

148. As regards thermo-electric currents, the characteristic of crystalline sub-
stance must be, that bars cut from it in different directions would, when treated
thermo-electrically as linear conductors, be found in different positions in the
thermo-electric series; or that two bars cut from different directions in the sub-
stance would be thermo-electrically related to one another like different metals.
This property has been experimentally demonstrated by SvanBERG, for crystals of
bismuth and antimony ; and there can be no doubt but that other natural metallic
crystals will be found to possess it. I have myself observed, that the thermo-
electric properties of copper and iron wires are affected by alternate tension and
relaxation in such a manner, as to leave no doubt but that a mass of either
metal, when compressed or extended in one direction, possesses different thermo-
electric relations in different directions. Fragments of different metals may be
put together so as to form solids, possessing by structure the thermo-electric
characteristic of a crystal, in an infinite variety of ways. Thus, a structure con-
sisting of thin layers alternately of two different metals, possesses obviously the
thermo-electric qualities of a crystal with an axis of symmetry. I have inves-
tigated the thermo-electric properties in all directions of such a structure, in terms
of the conducting powers for heat and electricity, and the thermo-electric powers,
of the two metals of which it is composed; and bars made up of alternate layers
of copper and iron, one with the layers perpendicular, another with the layers
oblique, and a third with the layers parallel, to the length, illustrating the theo-
retical results, which were communicated along with this paper, were exhibited to
the Royal Society. The principal advantage of considering metallic structures
with reference to the theory of thermo-electricity is, as will be seen below, that
we are so enabled to demonstrate the possibility of crystalline thermo-electric
qualities of the most general conceivable type, and are shown how to construct solids
(whether or not natural crystals may be ever found) actually possessing them.

149. The following two propositions with reference to thermo-electric effects
in a particular case of crystalline matter are premised to the unrestricted treat-
ment of the subject, because they will serve to guide us as to the nature of the
agencies for which the general mathematical expressions are to be investigated.

Prop. I. If a bar of crystalline substance, possessing an axis of thermo-electric
symmetry, has its length oblique to this axis, a current of electricity sustained in
it longitudinally will cause evolution of heat at one side, and absorption of heat
at the opposite side, all along the bar, when the whole substance is kept at the
same temperature.

DYNAMICAL THEORY OF HEAT. 155

Prop. II. If the two sides of such a bar be kept at different temperatures, and
a homogeneous conducting arc be applied to points of the ends which are at the
same temperature, a current will be produced along the bar, and through the arc
completing the circuit.

150. For proving these propositions, it will be convenient to investigate fully
the thermo-electric agency experienced by a bar cut obliquely from a crystalline
substance possessing an axis of symmetry, when placed longitudinally in a circuit
of which the remainder is composed of the standard metal, and kept with either
its sides or its ends unequally heated. Let ? and ¢ denote the thermo-electric
powers of two bars cut from the given substance in directions parallel and per-
pendicular to its axis of symmetry respectively. Let us suppose the actual bar to
be of rectangular section with two of its opposite sides perpendicular to the plane
of its length, and the axis of symmetry of its substance. Let a longitudinal section
in this plane be represented by the accompanying diagram; let O A or any line
parallel to it be the direction of the axis of symmetry through any point ; and let
w denote the inclination of this line to the length of the bar. Let the breadth of
the two opposite sides of the bar perpendicular to the plane of the diagram be
denoted by a, and in the plane of the diagram, 6. The area of the transverse sec-
tion of the bar will be ad; and therefore if Y denote the strength, and 7 the inten-
sity of the current in it, we have,—
ne
ab

151. We may suppose the current, itself parallel to the length of the bar
and in the direction from left to right
of the diagram, to be resolved, at any
point P at the side of the bar, into
two components in directions parallel
and perpendicular to OA, of which
the intensities will be 7 cos w, and
2 SiN w, respectively. The former of
these components may be supposed to
belong to a system of currents crossing
the bar in lines parallel to OA and

passing out of it, across the side C D, into a conductor of the standard metal ;
and the latter, to a system of currents entering the bar across C D, from the same
conductor of standard metal, and crossing it in lines perpendicular toO A. The
, resultant current in the supposed standard metal beside the bar will clearly be
parallel to the length, and can therefore (this metal being non-crystalline) pro-
duce no effect influencing the thermal agency at the side of the bar or within it.
The inclinations of the currents to a perpendicular to the separating plane of the

two metals being respectively 90°—w and , their strength per unit of area of this
VOL. XXI. PART I. 2T

j=

156 PROFESSOR W. THOMSON ON THE

plane, obtained by multiplying their intensities by the cosine of those angles re-
spectively, will be each equal to

2 cos ® sin W.
Hence the absorptions of heat which they will produce at the surface of separa-
tion of the metals per unit of area per second will be,

‘ie A 1 :
—jzicoswsinw iO, and zicoswsinwith,

respectively. According to the general principle of the superposition of thermo-
electric actions stated above, the sum of these is the rate of absorption of heat per
unit of surface, when the two systems of currents coexist. But the resultant of
these systems is simply the given longitudinal current in the bar, with no flow,
either out of it or into it, across any of its sides. _ Hence, a simple current of in-
tensity 7, parallel to the sides of the bar, causes absorption of heat at the side
C D, amounting to

7 icos w sin w t(p — 6),

per unit of area per second; and the same demonstration shows that an equal
amount of evolution must be produced at the opposite side C’ D’. These effects
take place quite independently of the matter round the bar, since the metal
carrying electric currents which we supposed to exist at the sides of the bar in
the course of the demonstration, can exercise no influence on the phenomena.

152. If 7 denotes the length of the bar, the area of each of the sides perpendi-
cular to the plane of the diagram will be / a; and therefore, the absorption over
the whole of the side C D, and the evolution over the whole of the other side CD’,
per second will be

a

z ilacos w sin wt (p — 6),
biel ;
or 7 VG cos # sin wt(p—@).

It is obvious, that there can be neither evolution nor absorption of heat at the
two other sides.

153. An investigation, similar to that which has just been completed, shows
that if the actual current enter from a conductor of the standard metal at one
end of the bar, and leave it by a conductor of the same metal at its other end,
the absorption and evolution of heat at these ends respectively will amount to

vy (¢ 0 cos? w + th sin? w)
per second.

154. Let us now suppose the two sides CD, C’ D to be kept at uniform tem-
peratures, T, T’, and the two ends to be kept with equal and similar distributions —
of temperatures, whether a current is crossing them or not. Then if a current of
strength Y be sent through the bar from left to right of the diagram, in a circuit

DYNAMICAL THEORY OF HEAT. 157

of which the remainder is the standard metal, there will be reversible thermal
action, consisting of the following parts, each stated per unit of time.

(1.) Absorption amounting to © (2) 5 y, ina locality at the temperature T.

(2.) Evolution amounting to a (vy y, ina locality at the temperature T’,
(3.) Absorption amounting to ny at one end, (that beyond C C,)
and (4.) Evolution amounting to «my at the other end ;

where, for brevity, o(1) and o() are assumed to denote the values of

5 (p—O) sin w cos w, at the temperatures T and T’; and mn the mean value of

(0 cos? w +@ sin? w) for either end of the bar. The contributions towards the sums

appearing in the general thermo-dynamic equations which are due to these items
of thermal agency, are as follows :—

[ @) = a(n) | ; Y towards =H,,
and Es _ ae | oY towards = =e

the thermal agencies at the ends disappearing from each sum, in consequence of
their being mutually equal and opposite, and being similarly distributed through
localities equally heated. Now when every reversible thermal effect is included,
H,
t

the value of s— must be zero, according to the second general law. Hence

either 28 - a) must vanish, or there must be a reversible thermal agency

a(t) ar)
lar

not yet taken into account. But probably may not vanish, that is,

ra)
e
with the temperature for metallic combinations structurally crystalline: (for a
bar cut obliquely from a solid consisting of alternate layers of copper and iron,
for instance, the value of o decreases to zero, as the temperature is raised from
an ordinary atmospheric temperature up to about 280°, and has acontrary sign for
higher temperatures.) Hence, in general, there must be another reversible ther-
mal agency, besides the agencies at the ends and at the sides of the bar which we
have investigated. This agency must be in the interior; and since the substance
is homogeneous, and uniformly affected by the current, the new agency must be
uniformly distributed through the length, as different points of the same cross
section can only differ in virtue of their different circumstances as to temperature.
If there were no variation of temperature, there could be no such effect anywhere
in the interior of the bar; and therefore, if dt denote the variation of tempera-

may vary with the temperature, for natural crystals, and it certainly does vary

158 PROFESSOR W. THOMSON ON THE

ture in an infinitely small space dz across the bar in the plane of the diagram,
and x an unknown element, constant or a function of the temperature, depending
on the nature of the substance, we may assume

at

t% a
as the amount of absorption, per unit of the volume of the bar, due to a current of
intensity 7, by means of the new agency. The whole amount in a lamina of
thickness d x, length /, and breadth a perpendicular to the plane of the diagram,
is therefore

ax S alde,
l
or Y 5 xu.

As there cannot possibly be any other reversible thermal agency to be taken into
account, we may now assume

2H=75{Lo@-o@)]+f- xa } i ee
ee ee Ae 1s eee

The second General Law showing that = = must vanish, gives, by the second
of these equations,

a(t) _ 27") es
mae ae: % dt =0 stest eee

Substituting, in place of 1, ¢, and differentiating with reference to this variable,
we have, as an equivalent equation,

2 fa)
PES ey ee eS
sae dt dt
and using this in (22), we have
J
SIH “peat de sae. © betas Sine See
Bypand

This expresses the full amount of heat taken in through the agency of the cur-
rent ; of which the mechanical equivalent is therefore the work done by the
current. Hence (according to principles fully explained above) the thermal cir-
cumstances actually cause an electro-motive force F, of which the amount is given

by the equation
l aa @ J
F — J oa ¢t dt . . . . . (27),

to act along the bar from left to right of the diagram; which will produce a cur-
rent, unless balanced by an equal and contrary reaction. This result both esta-

‘DYNAMICAL THEORY OF HEAT. 159

blishes Proposition II., enunciated above in § 149, and shows the amount of the
electro-motive force producing the stated effect, in terms of T and T’, the tempera-
tures of the two sides of the bar, the obliquity of the bar to the crystalline axis of
symmetry, and the thermo-electric properties of the substance; since, if 0 and
p denote its thermo-electric powers, along the axis of symmetry, and along lines
perpendicular to this axis, at the temperature 7, and w the inclination of this axis
to the length of the bar when the substance is at the temperature ¢, we have

2 = 5 (p — 8) sina cos : Tre. ky

155. By an investigation exactly similar to that of § 115 which had reference to
non-crystalline linear conductors, we deduce the following expression for the
electro-motive force, when the ends of the bar are kept at temperatures T, T’, from
the terminal thermal agency 4, of a current investigated in § 153.

4h sat
F=s/' 7 ut ; : , : ‘ (29),

where

n= 50 cos? w + @ sin? a) ‘ , : (30).

§§ 156-170. On the Thermal Effects and the Thermo-electric Excitation of Electrical
Currents in Homogeneous Crystalline Solids.

156. The Propositions I. and II., investigated above, suggest the kind of assump-
tions to be made regarding the reversible thermal effects of currents in uniformly
heated crystalline solids, and the electro-motive forces induced by any thermal
circumstances which cause inequalities of temperature in different parts. The
formule expressing these agencies in the particular case which we have now in-
vestigated, guide us to the precise forms required to express those assumptions
in the most general possible manner.

157. Let us first suppose a rectangular parallelepiped (a, b, c) of homogeneous
crystalline conducting matter, completely surrounded by continuous metal of the
standard thermo-electric quality touching it on all sides, to be traversed in any
direction by a uniform electric current, of which the intensity components parallel
to the three edges of the parallelepiped are h, 2, 7, and to be kept in all points at a
uniform temperature ¢. Then taking ¢, 0, 1, to denote the thermo-electric powers
of bars of the substance cut from directions parallel to the edges of the parailele-
piped, quantities which would be equal to one another in whatever directions
those edges are if the substance were non-crystalline; and 0 6”, d’, 6’, v, \’,
other elements depending on the nature of the substance with reference to the
directions of the sides of the parallelepiped, to which the name of thermo-electric

obliquities may be given, and which must vanish for every system of rectangular
VOL. XXI. PART I, 2U

160 PROFESSOR W. THOMSON ON THE

planes through the substance, if it be non-crystalline; we may assume the fol-
lowing expression for the reversible thermal effects of the current :—

Quo=bey hO+ig" +j¥)
Qen=eas hO+iprjy) ne eae
Qu n= aby (hO Fig’ +5)

where Qo», Qa» Qa», denote quantities of heat absorbed per second at the
sides by which positive current components enter, and quantities evolved in the
same time at the opposite sides. Hence, if the opposite sides be kept at different
temperatures, currents will pass, unless prevented by the resistance of surround-
ing matter; and the electro-motive forces by which these currents are urged, in
directions parallel to the three edges of the parallelepiped, have the following ex-
pressions, in which w a, vb, and w ¢ denote the difference of temperature between
corresponding points in the pairs of sides bc, ca, and a6, respectively reckoned
positive, when the temperature increases in the direction of positive components
of current ;

E=~—a (ub+v@+w 6")

F=—b(uf’+upi+w’) (32).

G=-c(uV+uy’+wy)

The negative signs are prefixed, in order that positive values of the electro-mo-
tive components may correspond to forces in the direction assumed for positive
components of current.

158. The most general conceivable elementary type of crystalline thermo-elec-
tric properties is expressed in the last equations, along with the equations (31)
by which we arrived at them, and we shall see that every possible case of thermo-
electric action in solids of whatever kind may be investigated by using them with
values, and variations it may be, of the coefficients ¢, 6, &c., suitable to the cir-
cumstances. It might be doubted, indeed, whether these nine coefficients can be
perfectly independent of one another; and indeed it might appear very probable
that they are essentially reducible to six independent coefficients, from the extra-
ordinary nature of certain conclusions which we shall show can only be obviated

noe
Sites dike =P, C= y, and p=)”
Before going on to investigate any consequences from the unrestricted funda-
mental equations, I shall prove that it is worth while to do so, by demonstrat-
ing that a metallic structure may be actually made, which, when treated on
a large scale as a continuous solid, according to the electric and thermal condi-

DYNAMICAL THEORY OF HEAT. 161

tions specified for the substance with reference to which the equations (31) and
(32) have been applied, shall exhibit the precise electric and thermal properties
respectively expressed by those sets of equations with nine arbitrarily prescribed
values for the coefficients 6, p, &c.

159. Let two zigzag linear conductors of equal dimensions, each consisting of
infinitely short equal lengths of infinitely fine straight wire alternately of two dif-
ferent metals, forming right angles at the successive junctions, be placed in per-
pendicular planes, and touching one another at any point, but with a common
straight line joining the points of bisection of the small straight parts of each

ca
S

conductor. Let an insulating substance be moulded round them, so as to form a
solid bar of square section, just containing the two zigzags imbedded in it in planes
parallel to its sides. Although this substance is a non-conductor of electricity,
we may suppose it to have enough of conducting power for heat, or the wires of
the electric conductors to be fine enough, that the conduction of heat through the
bar when it is unequally heated may be sensibly the same as if its substance were
homogeneous throughout, and, consequently, that the electric conductors take at
every point the temperatures which the bar would have at the same point if they
were removed. Let an infinite number of such bars, equal and similar, and of the
same substance, be constructed; and let a second system of equal and similar bars
be constructed with ZIg7a8 conductors of different Y
metals from the former; and a third with other Yj Gy
different metals: the sole condition imposed on the 7

different zigzag conductors being that the twoin WZ
each bar, and those in the bars of different systems, ™
exercise the same resistance against electric con- VY
duction. Let an infinite number of bars of the first
set be laid on a plane, parallel to one another, with
intervals between every two in order, equal to the
breadth of each. Lay perpendicularly across them ae
an infinite number of bars of the second system similarly disposed relatively
to one another ; place on these again bars of the first system, constituting another
layer similar and parallel to the first; on this, again, a layer similar and parallel
to the second; and so on, till the thickness of the superimposed layers is equal
to the length of each bar. Then let an infinite number of the bars of the third
system be taken and pushed into the square prismatic apertures perpendicular to
the plane of the layers; the cubical hollows which are left (not visible in the

NS
SS

AX \\ W

\

Us
\
MOO

NX

SS

7

SS QQ
A

162 PROFESSOR W. THOMSON ON THE

diagram) being previously filled up with insulating matter, such as that used in
the composition of the bars. Let the complex solid cube thus formed be coated
_round its sides with infinitely thin connected sheets of the standard metal, so
thin that the resistance to the conduction of electricity along them is infinitely
great, compared to the resistance to conduction experienced by a current tra-
versing the interior of the cube by the zigzag linear conductors imbedded in it.
(For instance, we may suppose the resistance of four parallel sides of the cube to
be as great as, or greater than, the resistance of each one of the zigzag linear con-
ductors.) Let an infinite number of such cubes be built together, with their struc-
tural directions preserved parallel, so as to form a solid, which, taken on a large
scale, shall be homogeneous. A rectangular parallelepiped, adc, of such a solid,
with its sides parallel to the sides of the elementary cubes, will present exactly
the thermo-electric phenomena expressed above by the equations (31) and (32)
provided the thermo-electric powers w,, @,', @,", @,", @,, @W,; D,”, B,”, and
@D,, W;, W,", @,;”, of the metals used in the three systems, fulfil the followin

conditions :— ¥

1(@,+ 0, +3," + w,”) = 8,

4(@,- @)=%, 4(@,"-B,")=0,

4 (@, + W, + W,” +W,”") =, (38). ‘
z (@, a @,') a fp’; t (@,” a w,”’) = p",

4 (@, + @, + @," + W,") = ¥,

4(@; — W;) =. + (@," — @,”) = ¥’.

160. To prove this, let us first consider the condition of a bar of any of the
three systems, taken alone, and put in the same thermal circumstances as those in
which each bar of the same system exists in the compound mass. If, for instance,
we take a bar of the first system, we must suppose the temperature to vary at the
rate uw per unit of space along its length; at the rate v across it, perpendicularly to
two of its sides; and at the rate w across it, perpendicular to its other two sides.
If 7 be its length, and ¢ the breadth of each side, its ends will differ in temperature
by wZ; corresponding points in one pair of its sides by ve, and corresponding
points in the other pair of sides, by we. Now, it is easily proved that the longi-
tudinal] electro-motive force (that is, according to the definition, the electro-motive
force between conductors of the standard metal) would, with no difference of
temperatures between its sides, and the actual difference w/ between its ends, be
equal to 4 (aw, + w,) wl, if only the first of the zigzag conductors existed imbedded
in the bar, or equal to 3 (w," + «,”) wl, if only the second ; and, since the two have
equal resistances to conduction, and are connected by a little square disc of the
standard metal, it follows that the longitudinal electro-motive force of the actual
bar, with only the longitudinal variation of temperature, is

+, Oy a Bat.

DYNAMICAL THEORY OF HEAT. 163

Again, with only the lateral variation ve, we have in one of the zigzags a little
thermo-electric battery, of a number of elements amounting to the greatest integer

in aS , which is sensibly equal to = since the value of this is infinitely great; the

electro-motive force of each element is (w, — w,’) v¢; and, therefore, the whole
electro-motive force of the zigzag is = x(@—-@,') vé, or $1 x (@,-—o,)v. This

battery is part of a complete circuit with the little terminal squares and the other
zigzag, and therefore its electro-motive force will sustain a current in one direc-
tion through itself, and in the contrary through the second zigzag; but since the
resistances are equal in the two zigzags, and those of the terminal connections may
be neglected, just half the electro-motive force of the first zigzag, being equal to
the action and reaction between the two parts of the circuit, must remain ready
to act between conductors applied to the terminal discs of the standard metal. In
| the circumstances now supposed, the second zigzag is throughout at one temper-
ature, and therefore has no intrinsic electro-motive force; and the resultant in-
trinsic electro-motive force of the bar is therefore

$1 (@,— Wy’) v-
Similarly, if there were only the lateral variation we of temperature in the bar,
we should find a resultant longitudinal electro-motive force equal to

41 (eo, — Bw.
If all the three variations of temperature are maintained simultaneously, each

will produce its own electro-motive force, as if the others did not exist, and the
| resultant electro-motive force due to them all will therefore be,—

l f " wm iy “ur UL
7a (@, + @ + @W," + W,")u + (@W, — W) vu + @W," — W,") we.

This being the electro-motive force of each bar of the first system in any of
the cubes composing the actual solid, must be the component electro-motive force
of each cube in the direction to which they are parallel; and, therefore,

at { (@, + @W + W," + W,")u+ (@W, — W)v t+ (wy ,")w }

must be the component electro-motive force of the entire parallelepiped in the same
direction. Similar expressions give the component electro-motive forces parallel
to the edges 6 and ¢ of the solid, which are similarly produced by the bars of the
second and third systems, and we infer the proposition which was to be proved.
161. Cor. By choosing metals of which the thermo-electric relations, both to the
standard metal and to one another, vary, we may not only make the nine co-
efficients have any arbitrarily given values for a particular temperature, but we
may make them each vary to any extent with a given change of temperature.
162. For the sake of convenience in comparing the actual phenomena of ther-
mo-electric force in different directions presented by an unequally heated crystal-
VOL. XXI. PART I. 2x

164 PROFESSOR W. THOMSON ON THE

line solid ; let us now, instead of a parallelepiped imbedded in the standard metal,
consider an insulated sphere of the crystalline substance, with sources of heat
and cold applied at its surface, so as to maintain a uniform variation of temper-
ature in all lines perpendicular to the parallel isothermal planes. Let the rate of
variation of temperature per unit of length, perpendicular to the isothermal sur-
faces, be g, and let the cosines of the inclinations of this direction to the three rect-
angular directions in the substance to which the edges of the parallelepiped first
considered were parallel, and which we shall now call the lines of reference, be
I, m, n, respectively. Then if we take
Gls eo GW= Uy Geae,

the substance of the sphere will be in exactly the same thermal condition as an equal
spherical portion of the parallelepiped; and it is clear that the preceding expres-
sions for the component electro-motive forces of the parallelepiped will give the
electro-motive forces of the sphere between the pairs of points at the extremities
of diameters coinciding with the rectangular lines of reference, if we take each of
the three quantities, a, >, c, equal to the diameter of the sphere. Calling this
unity, then we have

—-E=u9 +vV%4+wl
—F=uf’+vpd+uP - (34).
—-G=uVtuvt+uy

' According to the definition given above (§ 144, Def. 3), it appears that these
quantities, E, F, G, are the three components of the intrinsic electro-motive force at
any point in the substance, whether the portion of it we are considering be limited
and spherical, or rectangular, or of any other shape, or be continued to any in-
definite extent by homogeneous or heterogeneous solid conducting matter with
any distribution of temperature through it. The component electro-motive force
P along a diameter of the sphere inclined to the rectangular lines of reference at
angles whose cosines are /, m, ”, is of course given by the equation
P=EBi4 Pa eGn.- «.. *) Po) oan

which may also be employed to transform the general expressions for the compo-
nents of the electro-motive force to any other lines of reference.

163. A question now naturally presents itself, Are there three principal axes at
right angles to one another in the substance possessing properties of symmetry,
with reference to the thermo-electric qualities, analogous to those which have been
established for the dynamical phenomena of a solid rotating about a fixed point,
and for electro-statical and for magnetic forces, in natural crystals or in sub-
stances structurally crystalline as regards electric or magnetic induction? The
following transformation, suggested by Mr Stokes’ paper on the Conduction of
Heat in Crystals,* in which a perfectly analogous transformation is applied to the

* Cambridge and Dublin Mathematical Journal.

DYNAMICAL THEORY OF HEAT. 165

most general conceivable equations expressing flux of heat in terms of variations
of temperature along rectangular lines of reference in a solid, will show the nature
of the answer.

164. The direction cosines of the line of greatest thermal variation, or the per-

pendicular to the isothermal planes, are me 7 a , where q, denoting the rate of
variation of temperature in the direction of that line, is given by the equation
= (wu? + yu? + w?) ee. ; A Ny Z (36).

Taking these values for /, m, m, in the preceding general expression for the electro-
motive force in any direction, we find

Pai {Owe prays Ge yyuw s+ (y+Ojuus(O+ pur}

the negative sign being omitted on the understanding that P shall be considered
positive when the electro-motive force is from hot to cold in the substance. This
formula suggests the following changes in the notation expressing the general
thermo-electric coefficients :-—
Pty =20,, V+ =29,, H+ GP = 2 Jo... GD
—P+P=2l,-VPt+ W=2y, —F +h" =235
which reduce the general equations, and the formula itself which suggests them,
to—
—-H=O0u+rt,1v+ 9,w+ qQw—Sv)
—F=),u+ gut w+ Qu-lw) : sy, (08),
—-G=¢,u+0,u+ bwt Cv—nu)

P— (v4 pv + bur + 2Ovw + 2p, wu4 24, uv) SMEG

165. The well-known process of the reduction of the general equation of the
second degree shows that three rectangular axes may be determined for which
the coefficients 6,, ~,, ),, in these expressions vanish, and for which, conse-
quently, the equations become

—E= 0u+(qw-Sv)

—-F= ¢v+(Qu-Zw) ; : - . (40),
—~G=yw+ @v—74)
P == (60 + pu + yu? ) ae eg ae ee eA.

166. The law of transformation of the binomial terms (, w— 3 v), &c., in these ex-
pressions is clearly, that if 9 denote a quantity independent of the lines of reference,
and expressing a specific thermo-electric quality of the substance, which I shall call
its thermo-electric rotatory power, and if A, u, vy denote the inclinations of a cer-

166 PROFESSOR W. THOMSON ON THE

tain axis fixed in the substance, which I shall call its axis of thermo-electric ro-
tation to any three rectangular lines of reference, then the values of Z, , 3 for
these lines of reference are as follows:—
€=0cosA, 7=E cOSp, S=0 Cosy.
w
g
varies most rapidly, to the axis of thermo-electric rotation, and if a, 6, y de-
note the angles at which a line perpendicular to the plane of this angle 7 is in-
clined to the axes of reference, we have

If ¢ denote the inclination of the direction (. ae ) , in which the temperature

yw—Sv=Eqsini cos a

3u—Cw=o sini cos B ; 3 : . (42).

Cv—nu =Eqsinicosy
Hence we see that the last terms of the general formula for the component elec-
tro-motive forces along the lines of reference express the components of an electro-
motive force acting along a line perpendicular both to the axis of thermo-electric
rotation, and to the direct line from hot to cold in the substance, and equal in
magnitude to the greatest rate of variation of temperature perpendicular to that
axis, multiplied by the coefficient o.

167. Or again, if we consider a uniform circular ring, of rectangular section,
, cut from any plane of the substance inclined at an angle A toa plane perpendicular
to the axis of thermo-electric rotation, and if the temperature of the outer and
inner cylindrical surfaces of this ring be kept each uniform, but different from
one another, so that there may be a constant rate of variation, g, of temperature
in the radial direction, but no variation cither tangentially or in the transverse
direction perpendicular to the plane of the ring, we find immediately, from (42),
that the last terms of the general expressions indicate a tangential electro-motive
force, equal in value to gq cos A, acting uniformly all round the ring. This
tangential force vanishes if the plane of the ring contain the axis of thermo-
electric rotation, and is greatest when the ring is in a plane perpendicular to the
same axis.

168. The peculiar quality of a solid expressed by these terms would be destroyed _
by cutting it into an infinite number of plates of equal infinitely small thickness,
inverting every second plate, and putting them all together again into a continu-
ous solid ; a process which would clearly not in any way affect the thermo-electric
relations expressed by the first term of the general expressions for the compo-
nents of electro-motive force; and it is therefore of a type, to which also belongs
the rotatory property with reference to light discovered by Farapay as induced
by magnetization in transparent solids, which I shall call dipolar, to distinguish
it from such a rotatory property with reference to light as that which is naturally
possessed by many transparent liquids and solids, and which may be called an

DYNAMICAL THEORY OF HEAT. 167

isotropic rotatory property. The axis of thermo-electric rotation, since the agency
distinguishing it as a line, also distinguishes between the two directions in it, may
be called a dipolar axis; so may the axis of rotation of a rotating rigid body,* or
the direction of magnetization of a magnetized element of matter; and its general
type is obviously different from that of a principal axis of inertia of a rigid body,
or a principal axis of magnetic inductive capacity in a crystal, or a line of mecha-
nical tension in a solid; any of which may be called an isotropic axis.

169. The general directional properties expressed by the first terms of the second
members of (40) are perfectly symmetrical regarding the three rectangular lines
of reference, and are of a type so familiar that they require no explanation here.
We conclude that every substance has three principal isotropic axes of maximum
and minimum properties regarding thermo-electric power, which are at right
angles to one another ; but that it is only for a particular class of conceivable sub-
stances that the thermo-electric properties are entirely symmetrical with reference
to these axes; all substances from which the rotatory power, e, does not vanish,
having besides a dipolar axis of thermo-electric rotation which may be inclined in
any way to them.

170. These principal isotropic axes lose distinction from all other directions in
the solid, when the thermo-electric powers along them (the values of the coeffi-
cients 0, @,)) are equal; but a rotatory property, distinguishing a certain line
as a dipolar axis, may still exist. By § 159, we see how metallic structures pos-
sessing any of these properties (for instance having equal thermo-electric power
in all directions, and possessing a given rotatory power, e, in a given direction
about a given system of parallel lines), may be actually made.

171. [ Added, July 1854.] It is far from improbable that a piece of iron ina
state of magnetization, which I have, since § 147 was written, ascertained to
possess different thermo-electric properties in different directions, may also possess
rotatory thermo-electric power,} distinguishing its axis of magnetization, which is
essentially, in its magnetic character, dipolar, as thermo-electrically dipolar also.

§§ 172-181.—On the general equations of Thermo-Electric Action in any homo-
geneous or heterogeneous crystallized or non-crystallized solid.

172. Let ¢ denote the absolute temperature at any point, z, y, z, of a solid. Let
0, p, y, O, f’, V', 0”, b”, L”, be the values of the nine thermo-electric coefficients,

* [Added, Liverpool, Sept., 27, 1854.|—As is perfectly illustrated by M. Foucautt’s beautiful
experiment of a rotating solid, placing its axis parallel to that of the earth’s, and so turned that it
_ may itself be rotating in the same direction as the earth; which the meeting of the British Associa-
tion just concluded has given me an opportunity of witnessing.

t (Added, Sept. 13, 1854.]—By an experiment made to test its existence, which has given only
negative results, I have ascertained that this “ rotatory power” if it exists in inductively magnetized
iron at all, must be very small in comparison with the amount by which the thermo-electric power,
in the direction of magnetization, differs from the thermo-electric power of the same metal not mag-
netized.

VOL. XXI. PART I. 2Y

168 PROFESSOR W. THOMSON ON THE

for the substance at this point, quantities which may vary from point to point,
either by heterogeneousness of the solid, or in virtue of non-uniformity of its tem-
perature. Leth, 7, 7 be the components of the intensity of electric current through
the same point (2, ¥, 2).

173. Then, applying equations (31) of § 157 to infinitely small contiguous
rectangular parallelepipeds in the neighbourhood of the point (z, y, z), and de-
noting by H daz dy dz the resultant reversible absorption of heat occasioned by
the electric current across the infinitely small element dx dy dz, we find

tf d stm ieee ging: Ce.. Ppa Obl hea: deta eet he
Haz {5 hO+iG 4jV)+F RO +ipsj¥)+ E06 +ig' ssw } - «| £48),

174. By the analysis of discontinuous functions this expression may be applied
not only to homogeneous or to continuously varying heterogeneous substances, but
to abrupt transitions from one kind of substance to another. Still it may be conve-
nient to have formule immediately applicable to such cases, and therefore I add
the following expression for the reversible thermal effect in any part of the
bounding surface separating the given solid from a solid of the standard metal in
contact with it.

Qa=t[phOriprasVtqhOriprjyierherigrjy} . . (44),

where Q denotes the quantity of heat absorbed per second per unit of surface at
a point of the bounding surface, and (p, g, 7) the direction cosines of a normal at
the point.

175. Equations (34) give explicitly the intrinsic electro-motive force at any
point of the solid, when the distribution of temperature is given; but we must
take into account also the reaction proceeding from the surrounding matter, to
get the efficient electro-motive force determining the current through any part of
the body. This reaction will be the electro-statical resultant force due to accu-
mulations of electricity at the bounding surface and in the interior of the con-
ducting mass throughout which the electrical circuits are completed. Hence if V
denote the electrical potential at (x, y, z) due to these accumulations, the compo-
nents of the reactional electro-motive force are—

GON op Eee
ag? dy ” da"
and the components of the efficient electro-motive force in the solid, are therefore—
mS dV oh Wh dV
His Aegina

where E, F’, G are given by the following equations, derived from (34) by substi-
tuting for wu, v, w, their values _ “= 4, in terms of the notation now in-

troduced :—

DYNAMICAL THEORY OF HEAT. 169

Or es 6 dt gy , tt ow

dt . at DG
Beare cae! ae

(45).

di 4, sdb os, )
Sy aay a a Cog’

176. The body, being crystalline, probably possesses different electrical conduc-
tivities in different directions, and the relation between current and electro-motive
force cannot, without hypothesis, be expressed with less than nine coefficients.
These, which we shall call the coefficients of electric conductivity, we shall denote
by x, A, &c.; and we have the following equations, expressing by means of them
the components of the intensity of electric current in terms of the efficient elec-
tro-motive force at any point of the solid :—

See GaN) av
ees a) 48~ &) * G-2)
sie av BN aa dv

ion (E-F)+a(F-F)+x (6-3) Arce Came

2 aV dV LV
jan (8-45) + (PAE) +4 (0-1)

These equations (45) and (46), with

Gtaet Ee LS aa Se aR Teg)
which expresses that as much electricity flows out of any portion of the solid as
into it, in any time, (in all seven equations,) are sufficient to determine the seven
functions E, F, G, V, 4, 2, 7, for every point of the solid, subject to whatever con-
ditions may be prescribed for the bounding surface, and so to complete the pro-
blem of finding the motion of electricity across the body in its actual circum-

stances ; provided the values of — we a = are known, as they will be when

the distribution of temperature is given. We may certainly, in an electrical pro-
blem such as this, suppose the temperature actually given at every point of the
solid considered, since we may conceive thermal sources distributed through its
interior to make the temperature have an arbitrary value at every point. ,

177. Yet practically the temperature will, in all ordinary cases, follow by con-
duction from given thermal circumstances at the surface. The equations of mo-

' tion of heat, by which, along with those of thermo-electric force, such problems

may be solved, are as follows:—(1) Three equations,

170 PROFESSOR W. THOMSON ON THE

dt dt dt

ae ¢ att t*G)
7 at dt aby
= (VB e+e) a a
9 = — (me F 4m 4 mE)
a da dy dz

to express the components {, 7, 9 of the “flux of heat” at any point of the solid,
dt dt dt
dx’ dy? dz
k, 1, m, k’, &c., which may be called the nine coefficients of thermal conductivity of
the substance ;—and (2) the single nie art

d dy day
et gt ape -3{- (hO+ip’ +jy)+e Ori tiv, RO +ip+jy}

au n-SByos(e 4 eget i as

of which the first member expresses the rate at which heat flows out of any part
of the solid per unit of volume, and the second member, to which it is equated,
the resultant thermal agency (positive when there is on the whole evolution at
xyz produced by the electric currents.

178. The general treatment of these eleven equations (45), (46), (47), (48),

(49), leads to two non-linear partial differential equations of the second order and
degree for the determination of the functions ¢ and V.

179. It may be remarked, however, that the second term of the second mem-
ber of (49), when the prefixed negative sign is removed, expresses the frictional
generation of heat by currents through the solid, and will, therefore, when
the electro-motive forces in action are solely thermo-electric, be very small, even
in comparison with the reversible generation and absorption of heat in various
parts of the circuit, provided the differences of temperature between these different
localities are small fractions of the temperature, on the absolute scale from its
zero. Excepting then cases in which there are wide ranges (for instance, of
50° Cent. or more) of temperature, the second principal term of the second member
of (49) may be neglected, and the partial differential equations to which ¢ and V
are subject will become linear; so that one of the unknown functions may be
readily eliminated, and a linear equation of the fourth order obtained for the de-
termination of the other.

180. Farther, it may be remarked that probably in most, if not in all known ©
cases, the reversible as well as the frictional thermal action of the currents, when
excited by thermo-electric force alone, is very small in comparison with that of
conduction, perhaps quite insensible. [See above, §106.] Hence, except when
more powerful electro-motive forces than the thermo-electric forces of the solid
itself and of its relation to the conductors touching it at any part of its surface,

in terms of the variations of temperature ( ) multiplied by coefficients

DYNAMICAL THEORY OF HEAT. 171

act to drive currents through it, we may, possibly in all, certainly in many cases,
neglect the entire second member of (49) without sensible loss of accuracy; and
we then have a differential equation of the second order for the determination of
the temperature in the interior of the body, simply from ordinary conduction,
according to the conditions imposed on its surface. To express these last condi-
tions generally, a superficial application of the three equations (48) with their nine
independent coefficients is required.

181. When # is either given or determined in any way, the solution of the
purely electrical problem is, as was remarked above, to be had from the seven
equations (45), (46), and (47). These lead to a single partial differential equa-
tion of the second order for the determination of V through the interior, sub-
ject to conditions as to electro-motive force and electrical currents across the
surface, for the expression of which superficial applications of (45) and (46) will
be required. When V is determined, the solution of the problem is given by (45)
and (46), expressing respectively the electro-motive force and the motion of elec-
tricity through the solid.

[Additional Note Regarding the Discovery of Thermo-electric Inversions.]

In a foot-note on the passage quoted above from the Proceedings of the Royal Society of London,
I referred to phenomena observed in the use of certain alloys of bismuth and antimony in thermo-
electric circuits completed by copper and by silver, as constituting the first discovery of thermo-electric
inversions, having been described by Professor CummiNG, in a paper published as early as 1823 in
the Transactions of the Cambridge Philosophical Society. On becoming farther acquainted with
the experimental results contained in that important paper, I find that they include inversions, not
only in cases like those first mentioned, which might be regarded as anomalies dependent on singular
properties of strange alloys, but between pure metals, in various cases; and that the actual pheno-
menon in the case of copper and iron, the observation of which several years later by M. Becquzrer
had been very generally regarded as the first discovery of thermo-electric inversion, is there described ;
as the following extracts show :—

‘« Tf silver and iron wires be heated in connection, the deviation attains a maximum; diminishes
on increasing the heat, and again attains the former maximum on cooling.”—Camb. Phil. Trans.,
1823; Note on p. 61.

«« Addition to p. 61” [occurring in a page of additions at the end of the paper]. “ If gold, silver,
copper, brass, or zine wires be heated in connection with iron, the deviation, which is at first posi-
tive, becomes negative at a red heat.”

VOL. XXI. PART I. aay /

(A73er)

X.— An Investigation into the Structure of the Torbanehill Mineral, and of
various kinds of Coal. By Joun Hucurs Bennett, M.D., F.R.S.E., Professor
of the Institutes of Medicine in the University of Edinburgh. (With Two
Plates.)

(Read 6th February 1854.)

The investigation of which I am now about to give an account, was under-
taken with the view of determining whether the structure of the Torbanehill
mineral was similar to or unlike that of coal. I was aware that the subject
would be brought before a court of law, and that many scientific persons of great
eminence had already spent much time in the inquiry. With the understanding,
therefore, that my evidence, should it be required, was to be limited to the struc-
ture of coal and of the mineral in question, [ gave directions to Mr Bryson, the
optician, of this city, to make thin sections of attested specimens of various coals
and of the mineral, conceiving that a careful examination of them would easily
determine the point. It was soon apparent, however, that a far more extended
series of researches was necessary than I at first anticipated; but as it was also
evident, from the marked structural differences which were observed in the sec-
tions, that the investigation would not be destitute of positive results, I determined
on pursuing it to a conclusion.

The plan adopted was, in the first instance, to make myself familiar with the
structure of the ordinary household coals used in this city, of which those called
the Zetland and the Dalkeith or Buccleuch coals may be considered as the types.
I then examined the structure of the Wallsend, Newcastle, and various other
kinds of household coal, in every case observing, with magnifying powers of va-
rious diameters, thin sections made horizontally and longitudinally with the
line of stratification. J next examined similarly made thin sections of the Tor-
banehill mineral, and was struck with the remarkable dissimilarity which existed
between them. I now had numerous sections prepared of various cannel coals,
and having previously determined the appearances presented by true coal and by
the mineral, I was readily enabled to distinguish the various shades of differences
between them. I saw that although the cannel coals, and especially one of
them, the Brown Methil, approached in structural character to that of the Tor-
_ banehill mineral, it could still be distinguished from it by a practised eye; and
that although gradations existed between these different substances, there was
at least one element which served readily to characterize all the different kinds
of coal I had hitherto examined, and which was not present in the mineral. I

VOL. XXI. PART I, 3A

174 DR BENNETT ON THE STRUCTURE OF THE

now went over the sections of coal in the rich collection of Mr ALEXANDER Bry-
son of this city, and subsequently carefully examined the numerous sections made
by Dr ApAms of Glasgow. Before the trial of GinLEspPin versus RUSSEL came on,
Dr Apams, Mr QuEKETT, and myself, spent nearly an entire day together, exa-
mining each other’s specimens, and carefully re-investigating the whole subject.
It was then that the character of the ashes in the various substances we had
examined was pointed out to me by Dr Apams, who, in my opinion, is entitled’
to the greatest credit for the laborious, skilful, and successful efforts he has made
in determining the structure of numerous coals, and pointing out the differences
they exhibited, when compared with the Torbanehill mineral. At this meeting,
also, we compared the structure of coal with various kinds of recent woods, we
incinerated the mineral and certain coals, and carefully examined the ashes;
and there was established, as the result of this conjoined investigation, as well as
from the independent researches made by Dr Apams in Glasgow, by Mr QuEKETT
in London, and by myself in Edinburgh, the most perfect accord with regard to
all the facts which had been elicited during the inquiry.

At the commencement of the present session, I brought the subject under the no-
tice of the Physiological Society of this city, who appointed a committee, composed
of four gentlemen in addition to myself, all of whom had long been accustomed
to the use of the microscope, and were familiar with vegetable and animal struc-
tures. Three of these gentlemen, viz., Dr CoppoLp, and Messrs Bartow and Kirk,
made farther inquiries and researches, which served to elicit additional facts,
and to demonstrate, in the language of their report, that “the Torbanehill mi-
neral is widely different from every kind of coal.” Lastly, with a view of meet-
ing certain theoretical objections which have been advanced, I have carefully
examined the structure of various kinds of peat, as well as the stems of recent
ferns and several fossil plants, which have only served to establish the entire ab-
sence of connection between these substances and the Torbanehill mineral.

In now endeavouring to place in a condensed form the results of this extended
investigation before the Society, I propose, in the first place, to describe the facts,
as they may be easily demonstrated in the field of the microscope: Secondly, to
deduce from these facts the structural element which distinguishes every kind
of coal from the Torbanehill mineral, and explain the cause of the differences
which are recorded in the proceedings of the recent trial: Lastly, to offer a few
speculations as to the nature of this mineral, as distinguished from various kinds
of household and cannel coals.

I. When we examine a piece of undoubted coal, such as of the Zetland or Buc-
cleuch coals, it presents to the naked eye a fibrous structure, and has a black
shining streak. It has been found difficult to make thin sections of it, as in the
grinding process it readily crumbles down. But when a tolerably thin slice, made

TORBANEHILL MINERAL AND OF VARIOUS KINDS OF COAL. 175

in the direction of the fibres, is with great pains obtained, and examined with a
magnifying power of 200 diameters linear, it is then also seen to possess a fibrous
structure. (Plate I., fig. 3.) These fibres may be observed to be composed of a
reddish-brown coloured substance, in the centre of which is sometimes a dark
streak. Ovaland elongated transparent masses of a light yellow or reddish-brown
colour may also be seen running parallel with the fibres, and here and there are
colourless spaces, which strongly reflect light, and which are evidently filled with
a crystalline mineral substance. i

On examining a section horizontal to the former one, parallel with the plane
of stratification, a bistre-brown or blackish opaque mass is seen, containing a num-
ber of rings of a transparent yellowish or reddish colour, with an opaque centre.
These rings are from the 1000th to the 1500th of an inch in diameter, and re-
semble the transverse sections of tubes running at right angles to the fibres of the
coal. (Plate I., figs. 1 and 2.) There may also be observed larger masses of a
reddish-brown transparent material, varying in size from the jth to the sioth
of an inch in diameter. There are also visible, circles or rings of a rich golden
yellow matter, much larger, and varying in size from the 50th to the 6th of an
inch, which have been described by some as seeds or spore cases. (Plate I., fig. 1.
Plate IL., figs. 13 and 14.)

Similar appearances may be observed in the Wallsend, Newcastle, and all the
other household coals I have examined, although in some of them, especially
Newcastle coal, this structure is more obscured than in the Scotch coal, by dense
black opaque matter. Here and there, however, in the Newcastle as well as in
the Hamilton and some other coals, it may be found to present a highly fibrous
fracture, minute chips of which exhibit at their edges distinctly dotted or porous
ducts. (Plate II., figs. 5, 6, 7, 8, and 9.)

_ On examining the Torbanehill mineral with the naked eye, it is destitute of a
fibrous structure, and presents a homogeneous appearance in whatever way it is
fractured or cut. It is tough and hard to break, when compared with coal, has a
dull brown streak, and is readily ground down into thin slices of any degree of
tenuity. Some specimens are of a dark, and others of a light brown colour. The
section of a dark specimen seen under a magnifying power of 200 diameters, pre-
sents, first, a number of yellowish and reddish-brown transparent masses, of a
rounded form with an irregular outline, varying in size, from the ,4,th to the
sooth of an inch in diameter (Plate L., fig. 10). These are surrounded by a dark
opaque substance, in which they appear to be imbedded, and in which no trace of
structure can be detected. These light and dark substances vary in relative
' amount in different specimens of the mineral, and according to the thickness of
the section. In some specimens, the rounded transparent masses are more widely
separated, by the opaque substance, but in others, they are often so close, that a
very thin section presents a homogeneous appearance of yellowish or reddish-

176 DR BENNETT ON THE STRUCTURE OF THE

yellow matter, resembling bees-wax, with only a few irregular spots of the black
matter. In some sections, especially of the light-brown specimens, the rounded
masses, as they are ground thinner, may be seen, as it were, to melt into one _
another (Plate I., fig. 11). In such sections, no difference whatever can be made
out, whether they be made in a longitudinal or in a horizontal direction. But in
certain sections, the yellow masses assume an elongated shape, so as to resemble
the appearance represented, Plate L., fig. 9.

In some thin sections these rounded transparent bodies can be separated from
one another ,and be distinctly seen to possess a radiated crystalline appearance,
strongly reminding one of the crystals of carbonate of lime which occur in urine.
(Plate IL., fig. 1.) At certain angles, also, a few of them refract light, and be-
come strongly tinted with the orange ray when polarized,—a circumstance per-
haps dependent on the admixture of mineral matter. When a section of the
mineral, presenting both the substances described is held over the flame of a lamp,
the yellow matter evaporates in the form of thick smoke, leaving the black mat-
ter unaffected, with large holes or loculi in it. It must be clear from this expe-
riment that the yellow matter is some bituminous or resinous substance, easily
decomposed by the heat of a lamp, and that the black matter is an earthy mate-
rial, which resists the same amount of heat. We can have no doubt, therefore,
that an easily volatilized and highly inflammable matter has concreted in the
form of rounded masses, and constitutes the light-coloured portion of the mineral
formerly described. Whether this be chemically the same as, or only allied to
bitumen, resin, or amber, I leave to be determined by chemists. But we may at
least correctly denominate it a Bituwminoid substance, that is, one which closely
resembles, even should it turn out not to be identical with, bitumen. The matter
in which this is imbedded seems for the most part to be composed of clay, or
_earthy matter which leaves a white ash, altogether destitute of structural traces,
and is equally amorphous in whatever direction the section of the mineral is ex-
amined.

Some portion of the Torbanehill mineral, however, has a tendency to split up
into thin laminee, and presents smooth or irregular depressions, dependent on the
presence of Stigmaria or other fossil plants, which, in these places, come in con-
tact with, or are imbedded in, the substance of the mineral. Thin sections of
such portions exhibit masses of a rich brown colour, composed of scalariform ducts
in great numbers, and occasionally the woody fibres and rings of coal. These
latter are most common where the mineral forms a junction with coal, and where
the one is more or less mingled, or alternates with the other. In these places the
ereat difference in structure between them is easily recognized both by the naked
eye, and by microscopic demonstration. By the naked eye, the black shining
layers of coal are easily distinguished from the brown dull appearance of the
mineral, and wherever such coal exists, the streak is dark and lustrous; wherever

TORBANEHILL MINERAL AND OF VARIOUS KINDS OF COAL. 177

the Torbanehill mineral is pure, and unmixed with vegetable matter, it exhibits
the dull brown streak. Insuch places, the mineral is characterized, under the mi-
croscope, by its yellow masses and black basis; the coal, by its rich brown fibrous
structure. (Plate I., fig. 12, and Plate II. fig. 2.) Occasionally sections at the
point of junction, prove that the scalariform tissue, like the substance of coal, is
very friable and easily broken down. This fact which was pointed out to me by
Mr Kirk, induced him to think that the amorphous basis. might be composed of
such tissue disintegrated, a supposition negatived by the absence of all trace of
structure through the mineral generally.

From what has been said it must be evident, that there is a wide distinction
between all kinds of household coal and the Torbanehill mineral, and the correct
discrimination between the fibrous, woody texture of the one, and the granular
bituminoid, and earthy substance of the latter, will enable us to understand the
more confused texture presented in certain cannel coals, which it has been con-
tended are identical in structure with the mineral.

I have examined a large number of cannel coals, and in every case have been
enabled to recognise the fibrous structure of the longitudinal section, and the ap-
pearance of rings in the transverse sections, as they are seen in household coal.
They contain, however, a greater or less number of the bituminiod masses, identical
with those which constitute the principal substance of the Torbanehill mineral.*
(Plate I., figs. 4 to 9.)

The Capeldrae and brown Methil coals are especially rich in these bitu-
minoid bodies, and in consequence have been regarded as identical in structure
with the mineral. In some sections of the latter coal, they are almost as nume-
rous as those in the dark specimens of the Torbanehill mineral; but a careful
examination will show that it also possesses the same organic structure as coal,
and may be at once distinguished by its reddish fibres, when cut in one direction,
and by the distinct rings, though few in number, observed on a transverse section.
(Plate L, figs, 8 and 9.)

I consider that this proof of structure in the brown Methil coal, is decisive of
the question as to the distinction between coal and the Torbanehill mineral.
Every one allows, that of all the cannel coals, the brown Methil is the one which
most closely resembles it. It has also been reported that no difference can be de-
tected between them by the aid of magnifying glasses. To this I may reply, that
I have always been able to distinguish them at once; that I have never been de-
ceived in doing so, although the attempt has often been made; nor do I believe

* Tn reference to this point, I have carefully examined transverse and longitudinal sections of
the following household and cannel coals, namely,—Buccleuch, or Dalkeith; Zetland; Newcastle;
Wallsend; Jordan Hill; Knightswood; Arniston; Sheepmount; Drumfillan; Cowdenhill; Barton
Hill; Hastfield, Glasgow; Stonilaw, Glasgow; Gartnavel, Glasgow; Claycross ; Lesmahagow ;
Wemyss; Lochgelly; Capeldrae; Wigan; Civility Pit; Huddersfield; Bredisholm ; Black Methil;
and Brown Methil.

VOL. XXI. PART I. 3B

178 DR BENNETT ON THE STRUCTURE OF THE

that any histologist who has made himself acquainted with the structure of coal
on the one hand, and of the Torbanehill mineral on the other, could easily con-
found the two together.

There are two other modes of examination which also indicate the broad dis-
tinction in structure between coal and the mineral. These are by reducing them
to powder and to an ash.

The powder of household coal contains numerous short black fibres, separated
or aggregated together, mingled with mineral particles and fragments of cells.
That of the Torbanehill mineral is composed of transparent yellowish masses,
evidently the same as those seen in section, but more broken up, and without any
trace of an envelope, mingled with fragments and the debris of the dark amorphous
mineral matter. This mode of examination, though distinctive between the
household coals and the mineral, is not so much so, when the brown Methil coal
is chosen as the subject of comparison.

An examination of the ash, however, is still more characteristic. In the brown
or blackish ashes of coals will be found, 1s¢, A greater or less number of mineral
spicula, evidently the skeletons of the woody fibre; 2d, Siliceous masses of various
irregular forms, obtained from the interstices of the organic substance; 3d, Black
fibres, separated or in masses, evidently the woody fibre carbonized ; 4th, Flat
carbonaceous plates, presenting round apertures corresponding in size to the
woody cells which passed through them, and exhibiting at their margins sections
of larger circles, which doubtless bounded the large resin cells in the recent wood.
(Plate II., fig. 3). None of these appearances are visible in the ash of the Torbane-
hill mineral, when care is'‘taken to exclude such portions of it as are free from the
stigmaria or other plants imbedded in it. Indeed I myself have never seen such
appearances in the ash, even when no such precaution has been taken. Dr GroreGE
Witson gave me a considerable quantity of it, which everywhere exhibited
nothing but an amorphous material, such as might result from the incineration
of clay or other earthy non-organic substance. (Plate IIL., fig. 4). In all the
cannel coals, traces of these forms, though not so numerous or abundant, can be
seen. Mr QureKkeTT has even applied this test to Welsh anthracite, in which
substance no rings or fibrous structure can be made out in sections, yet where he
says, the ash gives unmistakable evidence of the presence of woody tissue.*

II. Such, then, are the facts which an investigation into the structure of coals
the one hand, and of the Torbanehill mineral on the other, has elicited. If the
account I have given of them be correct, it must be evident that the differences

* Quarterly Journal of Microscopical Science, No. VI., p. 43. This number of the Journal for
January 1854, was not published until February, after the present paper was written. I was enabled
however, by the kindness of Mr Hicutny, the publisher, to peruse a proof of Mr Quekerv’s valuable
paper, before my own was read to the Society, and to interpolate the above passage.

TORBANEHILL MINERAL AND OF VARIOUS KINDS OF COAL. 179

they present are marked and distinctive; that the one is essentially a woody

structure, whilst the other is not. Every kind of coal, including the Brown Methil,

may be at once distinguished from the Torbanehill mineral, by the rings contained
in a well-made transverse section. I further contend that such an appearance
constitutes, in the majority of cases, a practical and evident test, distinctive of
genuine coal, and that by means of it all kinds of known coal, whether house-
hold or cannel, can at once be distinguished from the Torbanehill mineral.*

Now if this be the case, it may well be asked how it happened that, at the
late celebrated trial,} so many persons, all of whom represented themselves as
being skilful observers with the microscope, should have been made to give dia-
metrically opposite evidence, not only as to matters of opinion, but as to what
appeared to be matters of fact? In endeavouring to place the remarkable histolo-
gical controversy which has originated out of the trial of GILLESPIE versus RUSSEL
on its correct basis, it must be remembered that unquestionable organic structure
is only present in the Torbanehill mineral at certain places. No one, for instance,
can doubt that the scalariform ducts seen by all parties are of vegetable origin;
but it is nowhere pretended that these were everywhere present in the mineral.
It is of great importance, therefore, not to confound the organic plants imbedded
in a substance, with the substance itself. The occurrence of Stigmaria or other
vegetable remains in coal, or in the Torbanehill mineral, no more constitute those
substances coal, than they convert sandstone and limestone into coal, in both
which rocks they are also found. Nor do I imagine it can be generally maintained
that because animal substances, such as teeth, jaw-bones, or the skeletons of
fishes and lizards, are occasionally found imbedded in stone, that therefore they
form an essential and necessary part of the stone itself. At the trial, great amount
of confusion resulted from not keeping this distinction clearly in view.

Thus when Mr QuexertT{ stated that all that which may be supposed like
vegetable structure in the Torbanehill mineral disappears when the structure is
thin, he was asked by the Dean of Faculty, “‘ When you speak of that which ap-
pears as vegetable structure, you mean those isolated fossil plants?” to which
Mr Quexerr unfortunately answered, “ Yes ;” for what he really meant was, not

* Considering that hitherto no distinct definition of coal has yet been made, and that the efforts
of mineralogists and chemists have only shewn that those differences they have detected are of degree
rather than of kind, the structural distinction here pointed out must be of great importance.

+ “ A full report of the trial before the Lord Justice-General and a special Jury of the Issues in
the action at the instance of Mr and Mrs Gituespis, of Torbanehill, against Messrs Russex and Son,
coal-masters, Blackbraes, for infringement of lease of coal, ironstone, &c. Reported by Mr Arex-
ANDER Watson Lyext, short-hand reporter. Edinburgh: Bell and Bradfute. London: Longman
and Co.; and W. Maxwell, 1853.” 4to, pp. 246.

This report is acknowledged by all parties to be very accurate, and it may therefore be regarded
as a trustworthy record of the scientific opinions held by numerous individuals, concerning the mine-
ralogical properties, chemical composition, and minute structure of the Torbanehill mineral and of
various kinds of coal.

} Mr Lyext’s Report, page 67.

180 DR BENNETT ON THE STRUCTURE OF THE

the isolated imbedded plants, but the structure of the mineral itself. In conse-
quence, the counsel for the pursuer and for the defender truly played at cross-
purposes throughout the whole of the structural evidence; for, notwithstanding
the clearness of Dr Batrour’s statement, he was asked, after saying that the mi-
neral consists of a plant, whether he had seen fossil plants in stone? to which he
answered, Yes. But then being asked whether he considered that an example of
such an appearance, he very correctly, according to his views, answered, No.

From the published report of the trial, however, by Mr LYELt, it is evident that
the eminent gentlemen who contended that the Torbanehill mineral was a vege-
table substance abounding in cells, did not adopt this idea because various plants
were imbedded in it, but because they believed the clear rounded masses I have
described were themselves vegetable cells. Unfortunately, the possibility of this
theory being adopted had not been anticipated, nor was it perceived by the counsel
for the pursuer. In consequence, the witnesses on the one side were made to declare
that the Torbanehill mineral was not vegetable, and on the other that it was,
without the true reason of this discrepancy ever having been made to appear.

Dr Barour stated in court, that he believed the yellow part of the Torbane-
hill mineral to consist of vegetable cells; that it was not the mere impression of
a foreign fossil, but the actual structure of the mineral at that place.* In the
same manner Dr Reprern, when asked,} ‘ What do you think these yellow spots
indicate?” replied, ‘‘ They indicate the existence of vegetable cells.” The reasons
he gave for so considering them were, ‘‘ That they can be perfectly isolated—they
project upon the edges of all sections of the mineral—they are rounded—they
are as uniform in size as the cells of other vegetable structures—the general ap-
pearance of the section is that of a piece of vegetable cellular tissue—the yellow
spots do not act upon polarized light, or act upon it very feebly.”

Dr GREVILLE, also, speaking of the same bodies, said,} that “he had no more
doubt of their being vegetable cells than he had of his own existence;” that “ in
one specimen it was so unequivocally marked, and so regular, that it might be .
compared to that of a recent plant;” and that “no person accustomed to bota-
nical sections would hesitate in believing it to be cellular tissue.”

From these quotations it must be evident that both parties saw the same
things, but that while on one side it was contended that they were not vegetable
cells, but bituminoid masses imbedded in clay, on the other it was strongly asse-
verated, in the language I have quoted, that because they were vegetable cells,
therefore the Torbanehill mineral was a fossil plant. But in consequence of the
reason of this difference in opinion not having been distinctly brought out in exa-_
mination, the greatest confusion seemed to prevail in the minds of judge, counsel,
and jury; and it was thought that the witnesses for the defender being skilful
botanists, were enabled to see what the witnesses for the pursuers did not see.

* Mr Lyetx’s Report, pp. 168-9, + Ibid, p. 170. + Ibid., pp. 171-2.

TORBANEHILL MINERAL AND OF VARIOUS KINDS OF COAL. Isl

This result, as well as the confusion occasioned by the examination of the wit-
nesses, is evident from the observations made by the learned Judge to the jury,
from which I shall take the liberty of quoting :—

* One general remark may be made on the microscopic testimony, and it is,
that there are those who see a thing, and also those who do not see it.—those
who do see it, cannot see # unless it is there, and those who cannot see it do not
see it at all. But very skilful persons looking for a thing and not seeing it, creates
a strong presumption that it is not there. But when other persons do find it, it
goes far to displace the notion that it isnot there. But there is another observa-
tion on the microscopic evidence that occurred tome. Ido not know whether
I am under any misapprehension, but I think that three, certainly two, of those
examined by the defenders are botanists also; and I do not think that any of those
examined for the pursuer, three of them from London, represented themselves as
botanists. Now the defenders’ witnesses are accustomed to look for plants, and
can understand them when they see them. The gentlemen on the other side,
again, looking for woody fibre or tissue, are not, as I understand, conversant or
skilful in fossil plants.” *

Now, so far from the botanists seeing what the histologists did not see, it is
nowhere made to appear in their evidence that they ever observed those rings on
a transverse section, which I have endeavoured to show are distinctive of true
coal. On the contrary, they contended that coal and the Torbanehill mineral were
‘similar in structure, the elements of the one existing in the other, both contain-
ing vegetable cells; that the numerous yellow clear masses observed in the latter
were in point of fact such cells, and constituted the proof of vegetable organi-
zation.

I think it of great importance to rescue the mode of investigation by means of
the microscope from all reproach in this case, and to point out that the discrepancy
_ which existed is not one of fact, but one of inference. I hope then it will be evi-
dent that the true scientific controversy is altogether connected with the question
of whether these yellow masses, which both parties saw, described, and figured,
are or are not vegetable cells.

Now the view taken up by myself from the first, and which was also taken
up by Dr Apams and Mr QueKerr, independently of each other, was that they
are not cells, but masses of a concrete bituminoid or resinoid substance, imbed-
ded in earthy matter. We could nowhere discover in them any trace of cell wall
or contents. Their mode of fracture was more crystalline in its character than
anything else; they occurred confusedly together, and nowhere presented that de-
finite arrangement to one another, or to ducts and woody tissue, which exists in
plants. Numbers of them present no envelope or definite boundary, but are scat-.

* Mr Lyett’s Report, pp. 238-9.
VOL. XXI. PART I. 3C

182 DR BENNETT ON THE STRUCTURE OF THE

tered through a substance often more than two feet deep, extending for acres,
and it may be for miles. If these yellow masses be cells, what is their origin?
They cannot come from the woody tissue of the neighbouring coal, for, as
we have endeavoured to show, such coal is destitute of them. The rings in
coal are much smaller in diameter, are of regular size, and present the cha-
racter of a tube cut transversely. Such rings could never be confounded with
the yellow masses of the mineral. But supposing these latter to be cells,
could such multitudes of them be derived from the gigantic ferns of the coal
formation, or such as are imbedded in the mineral? I think not; because the
amount of scalariform and woody tissue is too disproportioned to the number of
the cells to favour such an idea. Besides, what kind of force or power could
have been in operation that would have separated and collected the delicate
cells, and left the ducts and other tissues of the plants by themselves, and out
of sight, throughout such enormous masses. I have carefully examined the cells
in large ferns, and observed the singular markings of cellular tissue, woody
fibre, and scalariform ducts, many of them present, visible even to the naked
eye,—than which nothing can be more unlike the Torbanehill mineral. The
cells themselves are also larger, of more uniform size, and contain numerous
starch granules; whilst the true resin cells are exceedingly large and distinct,
strongly analogous, indeed, to what I have described as existing in the woody
texture of coal, but wholly dissimilar to any thing observable in the Torbane-
hill mineral. Such a view, indeed, would, it seems to me, lead to the extra-
ordinary conclusion that this mineral is composed of a vegetable tissue, more
cellular than any plant ever yet met with, recent or fossil, and so rich in cells as ~
to be wholly dissimilar to what we can even imagine to have existed, taking its
size and bulk into consideration. Such masses of cells could not have been formed
or nourished without ducts passing through them in various definite directions, to
convey a nutritive fluid; and yet we find such ducts only to be accidental, and only
distinctly connected with plants imbedded here and there in the general mass.
Whilst, then, the notion of these yellow masses being vegetable cells seems to
me opposed to every known or conceivable fact yet ascertained to exist in vegetable
histology, or from such as are demonstrable in the Torbanehill mineral, the theory
of their being bituminoid masses imbedded in clay, appears to be in perfect har-
mony with all of them, and especially answers the reasons given by Dr REDFERN.
With a view of determining whether the Torbanehill mineral could by any pos-
sibility be produced by a process similar to that of the formation of peat, which was
described at the last meeting of the Society by Dr FLemine,* I have examined vari-
ous specimens of peat, and have confirmed his description. They consist of mosses,
especially of the Sphagnum, the spiral cells of which plant are peculiar, and easily
recognized, associated with broken-down woody tissue, root-stalks, and bundles
* Proceedings of the Royal Society of Edinburgh. Session 1853-4, p, 216,

TORBANEHILL MINERAL AND OF VARIOUS KINDS OF COAL. 183

of simple ducts, more or less carbonized and condensed together. The deeper the
peat is taken from the bog, the more condensed, broken up, and altered these
textures are ; still, however, sufficiently retaining their characters to be readily
distinguishable. The peat of Scotland between this and Glasgow, and that of the
north of Ireland, of which I have examined numerous specimens, taken from
mountain bog, as well as the flow bog, are identical in structure. One specimen
of peat, however, given to me by Dr Train, which he obtained in Lancashire,
and which answers in description to what is called Pitch Peat, is blacker in
colour, the carbonizing process is more complete, and the vegetable tissues less dis-
tinct. But here and there, in a thin section of this peat, there exist rounded
masses of the same bituminoid character as are found in the cannel coals and in
the Torbanehill mineral. This fact confirms the theory formerly advanced, that
these bodies are not cells, but a concrete bituminoid substance, probably derived
from the beds of coal in Lancashire, in the immediate neighbourhood of the peat.

We may therefore conclude that every kind of coal has a distinctly woody
basis, which is easily demonstrated by its longitudinal and transverse sections ;
that the cannel coals have, in addition to this woody structure, a greater or less
number of the bituminoid masses imbedded in it; and that the Torbanehill mi-
neral has no such woody texture, but is essentially composed of the bituminoid
masses imbedded in clay.

| Il]. In the third place, the theory which I am disposed to put forward as
- most in harmony with the various facts and arguments previously stated, is as
follows :—1st, That. the various organic appearances found in the sections and
ashes of coal, are explicable by the supposition that coal is wood chemically
altered, and for the most part coniferous wood, or wood allied to it in structure,
because, from a careful comparison of recent fir wood with the various kinds of
coal, | find the structural appearances of the cellular tissue, resin cells, and ducts,
to be very similar. Further, no fir wood growing in this country contains spiral
ducts; and it is remarkable that no traces of such ducts are to be found in any
of the coals I have examined. Further, the assumption that coal is formed from
fir or allied woods, not only explains its structure, but accounts for the large
amount of bitumen, resin, or inflammable matter it contains, resin being a well-
known abundant product of the coniferous tribe of plants.*

2d, The Torbanehill mineral, although it presents essentially no traces of ve-

* In the above passage, I have carefully avoided any expression which would suggest the notion
* that in my opinion the wood from which coal is formed, is exclusively coniferous wood. I believe,
that with regard to the varicties and even genera of the plants of the coal-formation, there is still
much to be discovered. But so far as my examinations have gone, the appearances observed warrant
the general inference stated in the text, one which has also been arrived at by Mr Quexetr. (Mic,
Journal, No. vi. p. 42.) The important fact to be kept in remembrance is, that coal is fossil or
transformed wood, whilst the Torbanehill mineral, and all the shales which I have examined, are not.

184 DR BENNETT ON THE STRUCTURE OF THE

getable structure, is rich in the bituminoid substance ;—a circumstance, I think,
explained by the fact that it is found in the neighbourhood of coal, so that the
bituminoid or resinoid matter formed in the partially woody structure of the
latter has flowed out, mixed itself with, and solidified in the essentially earthy
substance of the former. It is easy to conceive how enormous pressure, con-
joined with chemical change and heat, may have effected this, and how some-
times such fluid bituminoid matter may have run into neighbouring beds of peat,
of clay, or even of sandstone. Facts, indeed, are not wanting to show that occa-
sionally large collections of such substance, almost pure, may be formed, unmixed
with either peat or clay, of which the remarkable specimen I now exhibit to the
Society, taken from the Binnie Quarry, and for which I am indebted to Dr Curis-
TISON, is an example. Fragments of this substance, under the microscope, closely
resemble the yellow masses which exist in the Torbanehill mineral.

In conclusion, I would remark that the controversy on this subject is only an
example of a far more extensive one which is now everywhere taking place
throughout the natural sciences, in reference to the influence which more im-
proved methods of research in chemistry and histology should exercise on our
thoughts and nomenclature. Those who, with myself, recognise that differences in
structure indicate differences in function, and that these should be studied as the
foundation for a correct classification, will recognise in the question. what is coal ?
an analogue to the questions, what is wood or coral ?—what is bone or tooth ?—
what is a fibrous or a cancerous tumour? The progress of science, and especially
of micro-chemistry, has already answered some of these questions, and will ulti-
mately determine others; and in doing so, will overthrow the more vague and
incorrect views and terms which previously prevailed. At the trial, indeed, it
was very plausibly argued, that, in a bargain between man and man, scientific |
terms were of no value, and that a whale among whalers was still a fish.* But
in this Society, as no naturalist, conversant with the structure and functions of
a whale, would for a moment suppose it to be a fish, because it inhabits the water
and resembles one ; so I contend no histologist, acquainted with the structure
and properties of the Torbanehill mineral, ought to maintain that it is coal, be-
cause it is dug out of the earth and burns in the fire.

* Mr Lyext’s Report, p, 231,

TORBANEHILL MINERAL AND OF VARIOUS KINDS OF COAL. 185

Description of the Plates.

Prare 1., Fig. 1. Transverse section of Buccleuch or Dalkeith coal, magnified 80 diameters linear.

: It displays imbedded in the bistre-brown mass, 1st, The rings described in the
text ; 2dly, The reddish masses supposed to be resin cells; and, 3dly, The
large circles considered to be sections of spore cases.

Fig. 2. Another portion of the same section, magnified 200 diameters linear, showing
more particularly the appearance of the rings held to be characteristic of coal.

Fig. 3. Longitudinal section of the same coal. 200 diameters linear.

Fig. 4. Transverse section of the Wemyss cannel coal, showing, in addition to the rings,
several bituminoid masses. 200 diameters linear.

Fig. 5. Longitudinal section of the Wemyss cannel coal. 200 diameters linear.

Fig. 6. Transverse section of the Lesmahagow cannel coal, showing a less number of the
rings, but a greater number of the bituminoid masses. 200 diameters linear.

Fig. 7. Longitudinal section of the Lesmahagow cannel coal. 200 diameters linear.

Fig. 8. Transverse section of the Brown Methil coal, showing very few of the rings, but a
greatly increased number of the bituminoid masses. 200 diameters linear,

Fig. 9. Longitudinal section of the brown Methil coal. 200 diameters linear.

Fig. 10. Transverse section of the darker coloured Torbanehill mineral, showing the bitu-
minoid masses imbedded in clay. No rings are anywhere visible. 200 diameters
linear.

Fig. 11. Transverse section of the lighter coloured Torbanehill mineral, showing the deep
orange-coloured masses, and the melting together of the bituminoid masses. 200
diameters linear.

In these sections it will be observed, that common coal abounds in the rings,
and possesses no bituminoid bodies. The cannel coals have rings and
bituminoid budies, whilst the Torbanehill mineral is principally composed
of the bituminoid masses without any rings at all. It will be further seen,
that in different cannel coals these various elements vary greatly in
amount.

Fig. 12. Transverse section of the Torbanehill mineral, at the upper portion of the seam,
where veins of coal run through it. 200 diameters linear.

Prate II. Fig. 1. Bituminoid masses imbedded in the clay of the Torbanehill mineral, at the edge
of a section, magnified 750 diameters linear, to show their radiated texture,
and mode of fracture.

Fig. 2. Section of the lighter coloured Torbanehill mineral, in which a plant is imbedded,
. showing the scalariform vessels. 200 diameters linear.

Fig. 3. Ashes of the Zetland coal, showing mineral masses and spicula, black fibres and
plates, perforated with round openings. 200 diameters linear.

Fig. 4. Ashes of the Torbanehill mineral, showing their amorphous structure. 200
diameters linear.

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( 187 )

XL—On certain Vegetable Organisms found in Coal from Fordd. By Joun
Hurton Batrour, M.D., F.L.S., Professor of Medicine and Botany in the Uni-
versity of Edinburgh.

(Read 20th February 1854.)

The Society has had its attention of late so much directed to the subject of
coal, that some apology, perhaps, is necessary for bringing this substance again
under notice. I may premise, however, that in doing so, it is not my intention
to revive the disputed question as to Boghead gas-coal, nor to take up the time of
the Society with what may be considered as unprofitable discussion. I purpose
to bring forward a few facts relative to a coal, concerning which there is no dis-
pute, and which presents some vegetable organisms and products calculated, in
my opinion, to throw light on the history of carboniferous deposits. Much of the
recent difference of opinion on the question of coal has arisen from the mode in
which some histologists have chosen to define it. I trust that the result of all our
discussions will be to lead to a fuller examination of coal in all its forms,—to a
comparison of specimens, both mineralogically and microscopically, from different
localities,—and, finally, to an extended report on the subject in which geologists,
chemists, and histologists will combine.

In the meantime, I feel that we are called upon to collect facts, and to bring
together authentic specimens in our public museums, which may aid in the in-
vestigation. I have already commenced the collection of specimens in the Mu-
seum of Economic Botany at the Botanic Garden, and I have secured the co-
operation of parties capable of giving most efficient assistance in this respect.
The establishment of a Museum of Economic Geology in Edinburgh will, it is
hoped, ere long supply the means of illustrating fully the coal-fields of Scotland.

The present communication is made in the hope that the facts brought under
notice may be useful in the elucidation of the nature of the plants which have
been concerned in the production of coal.

The coal to which I am now to refer, occurs at Fordel Collieries, near Inver-
keithing, in Fife; and the specimens have been kindly supplied by Mr Daw,
Comptroller of Customs at Leith, who has taken a deep interest in the appear-
ances and structures presented by coal, and has allowed no opportunity to pass of
making observations on it. _I take this opportunity of expressing publicly my
obligations to him.

The coal is a splint-coal, which, when burnt, yields a considerable amount of
ashes, and hence is not well suited for household purposes. It exhibits numer-

VOL. XXI. PART I. 3E

188 PROFESSOR BALFOUR ON CERTAIN VEGETABLE ORGANISMS

ous vegetable impressions, particularly of Sigillaria and Stigmaria. These plants
appear to have been concerned in the formation of this coal, and specimens in
the Edinburgh Botanical Museum seem to prove this. That these plants do fre-
quently form coal, has been long believed by geologists and fossil botanists ; but this
opinion has been lately called in question by Mr QuEeKert, who, as the result of his
histological researches, states that “ such plants rarely, if ever, form coal.” This
startling statement appears to me to be founded on very slender data. We un-
doubtedly meet with separate specimens of these plants converted into carbona-
ceous matter, and if so, why should they not occur in a similar condition in mass,
so as to form coal beds?

Sigillarias are perhaps the most important plants in the coal formation, form-
ing a conspicuous feature in almost every field, appearing in all the strata, and
very generally distributed both in the Old and New World. There are upwards
of sixty species described. The plants appear to have been Acrogenous, and to
have had a lax tissue, allied to the succulent ferns belonging to the suborders
Marattiacezee and Danzeaceze. Their roots, denominated Stigmarias, are also
very abundant, and are common in the underclay of coal beds, as well as in the
coal itself.

The tissue of these plants has in some instances been well preserved; in
other cases it has been much compressed, and so altered as to show scarcely any
structure under the microscope. J.D. Hooker remarks, “ Considering the exceed-
ingly lax and compressible tissue of the ordinary coal plants, it is not wonderful
that instructive specimens are rare. Plants whose tissues are so loose as to be
convertible after death into a mass of such uniform structure as coal, evidently
could not retain their characters well during fossilization.” The singularly
succulent texture, and extraordinary size of both the vascular and cellular tissue
of many Sigillarias indicate possibly a great amount of humidity. The vascular
tissue of Sigillarias consists chiefly of scalariform and dotted vessels; the former
marked by bars more or less complete, and the latter by dots or pits on the walls.
(Plate IL., figs. 6-11.)

The absence of other parts of plants, and indeed of any plants but the roots
of Sigillarias, in the underclay, seems to indicate that the soil was not fitted for
the growth of other vegetables. It is probable that the decay of those plants
whose roots struck into the underclay would produce a uniform bed of peat,
adapted to the growth of the ferns and other plants which are fossilized in the
superincumbent shales. Sigillarias also occur in the shale above the coal, and in
many cases their Stigmaria roots appear to have been incorporated with the coal
below.* QUEKETT, on the other hand, maintains that coal is not formed, in any
instances, from plants with a lax tissue, but in all cases from Coniferze; and

* J.D. Hooxsr, on the Plants of the Coal Measures, in Report of Geological Survey, vol. ii.

FOUND IN COAL FROM FORDEL. 189

he restricts his term coal to a substance formed of woody tissue of this nature.

As regards this point, I think he has come to a conclusion which is not con-
firmed either by the external configuration or by the internal structure of the
plants concerned in the formation of coal. The true characters of the coniferous
wood are the circular markings, with the dot in the centre, and hence the name
punctated or disc-bearing. This structure is seen both in recent Coniferee and in
the true fossil Coniferee, such as the Dadoxylons of the sandstones in this
neighbourhood. It is not however restricted to Conifers, for it has been detected
in Drimys Winteri, [licium floridanum, and other plants. This punctated struc-
ture is not easily demonstrated in the coal of the carboniferous epoch, although
it has been detected in the brown coal of the tertiary beds, according to Gorp-
PERT, and in the needle-coal of Bohemia (Plate IIL., fig. 5). What has been con-
sidered as punctated tissue in coal appears to be, in many instances, dotted or pitted
vessels (Plate IL., figs. 6-9), some of which assume a scalariform appearance (Plate
IL., fig. 10). These vessels (often with complete rounded or elliptical perforations,
owing to the disappearance of the walls) are seen evidently in Sigillarias; and
Bronenrart has figured them in his account of Sigillaria elegans. They occur in
Arniston, Newbattle, and other coals, found in the neighbourhood of Edinburgh ;
and now that I have seen them in the Fordel coal, in the very substance of Sigil-
laria, I look upon them as the pitted vascular tissue of that plant. In Fordel
and other coals, we also meet with true scalariform vessels (Plate II., fig. 11),
which may be looked upon as intermediate between spiral and pitted tissue.

- Insome specimens of Fordel coal, where the impressions of Sigillaria are very
evident, there is no difficulty in seeing under the microscope these pitted vessels,
having their walls covered with perforations (Plate IL., figs. 8, 9), and not as in
coniferous wood (Plate II., fig. 5), where the punctated discs are confined to two
sides of the tubes, and can only be seen properly when the section is made in the
line of the medullary rays. The absence of central punctation, the general distri-
bution of the perforations over the walls, and their close approximation, all, in my
opinion, show the tissue to be pitted vessels (Bothrenchyma or Taphrenchyma),
and not punctated woody tubes.

We have, then, in my opinion, evidence here, both from external characters
and microscopic texture, that the plants forming Fordel coal were in part SiaiL-
LARIAS. ‘The question then comes, What are these Sigillarias? Fossil botanists
place them among Acrogens, and in the immediate vicinity of Ferns. They seem
to have a close affinity to Lycopodiacee, and probably form a connecting link be-
tween them and Cycadaceze. We have the scalariform tissue of the one, and the
dotted tissue of the other. This appears to me to be a very interesting result of
microscopic investigation; and I think we shall be confirmed in this opinion by
what I have further to state in regard to Fordel coal.

I am also disposed to think that what Mr Qurexerr and Dr Bennett consider

190 PROFESSOR BALFOUR ON CERTAIN VEGETABLE ORGANISMS

to be the ends of woody coniferous tubes, are not so, but simply sections across
cavities or spaces containing orange or yellow matter ;—the depth of colour de-
pending on the thickness of the section. In many instances where yellow matter
exists in coal, we find it formed in cavities of different sizes, and in the centre it
is common to meet with dark-coloured carbonaceous matter. On a section, such
cavities in many instances exhibit a rounded contour, with a dark spot in
the centre. Rounded or elliptical bodies, having a cellular or spore-like aspect,
and containing yellow matter, occur more or less in all illuminating coals, whether
splint, cherry, or cannel.

The quantity of yellow matter in coals varies much. It abounds in many
good gas-giving coals, such as Boghead, Methil, and Capeldrae. Coal must be
regarded as a rock, varying in its composition in different localities. There is a
eradation in its structure and constitution in passing from anthracite to house-
hold and parrot coals; and the limit between coal and what is called bituminous
shale is by no means definite. Judging by microscopical and other characters,
as well as by chemical analysis, there seems no reason for separating Boghead or
Torbane, Capeldrae, Methil, and other brown parrot coals from the category of
true coals. Careful analyses show that the products of all are the same, viz., ammo-
niacal liquor, tar, naphtha, benzole, napthaline, grease-oil, paraffine, and pitch.
Bitumen, or a matter soluble in naphtha, exists in very small quantity in coals, and
is more abundant in English caking coals than in cannel coals. The quantity
of inflammable matter, or rather of hydrogen, in coals seems to determine the
quantity of fixed carbon. In such coals as Boghead the quantity of hydrogen
is very large, and hence the complete nature of the combustion.

In reviewing the plants which are concerned in the formation of coal, J. D.
Hooker, in his paper, published in the Reports of the Geological Survey of Great
Britain, remarks, that Coniferee are chiefly found in the sandstone; and their
remains being exceedingly rare in the clays, shales, and ironstones, it may be con-—
cluded that they were never associated with the Sigillarias and other plants which
abound in the coal seams, but that they flourished in the neighbourhood, and were
at times transported to these localities.

Mr Binney of Manchester gives an instance of an erect fossil conifer passing
from the roof of one coal seam through another one, and having deposited round
it many feet of sandstone, followed by underclay, a bed of coal, shale, and other
successive deposits. This is looked upon by some as a proof of the rapidity with
which the coal-beds were formed, of the rapid decomposition of those plants which
constituted the coal, in comparison with the coniferous wood, and of the probable
soft-tissued nature of the plants which formed that deposit.

In coal from Newbattle, I have seen a remarkable cellular structure contain-
ing yellow matter, associated with the ordinary dense carbonaceous matter form-
ing the darker portion of the coal. The specimen seems to show, that different

FOUND IN COAL FROM FORDEL. 19]

kinds of plants, some of them cellular, have entered into the composition of coal.
Believing Sigillarias and Stigmarias to have had a large amount of cellular tissue
in their structure, we can understand that in coal formed from them this tissue
may, in certain instances, remain more or less entire, while in other instances it
may have been compressed in such a way as to obliterate or rupture the cell-
cavities. Dotted vessels, moreover, are not so dense, nor so much thickened in
their walls, as woody tissue, and hence, in many cases, pressure may have in like
manner destroyed their characteristic appearance, and by the approximation of
their walls have given rise to some of the so-called fibrous appearances in coal.

Besides Sigillarias and Stigmarias, we also detect in the Fordel coal peculiar
rounded organisms, which have the appearance of seeds (Plate II., figs. 12, 13).
Dr FLemrne informs me, that similar bodies have been observed by him in coal,
and that he exhibited them to Mr Wirnam about twenty years ago. They have
also been seen by Dr Fiemine in Lochgelly and Arniston parrot, and in the coal
at Boghead; and from having observed them in cherry, splint, and cannel coals,
he is disposed to consider them as a somewhat common feature. I have seen
them in coal from Miller-hill, near Dalkeith, as well as in the coal from Fife.
They do not.appear to have been fully described. The nearest approach to them is
the Lycopodites, figured by Mr Morris in the Appendix to Mr Prestwicu’s paper
on the Geology of Coal-Brook Dale.* They appear to be certainly allied: to the
fructification of the Lycopodiaceze of the present day, more particularly to that
form of it which consists of two valves placed in apposition, and containing what
is called Lycopode-powder, or minute cells having a yellow glistening aspect, in-
terspersed sometimes with matter of a dark wine-colour.

These seed-like bodies in Fordel coal (Plate IL., figs. 13, 14, 15), I therefore con-
sider to be the sporangia or spore-cases of some plant allied to Lycopodium, per-
haps Sigillaria. They are remarkably preserved in the coal, and occur in many
instances in vast quantity. They have a rounded form,—their colour is dark
brown, and they seem to be formed by two valves inclosing a cavity which is often
filled with black carbonaceous matter (Plate IL., figs. 16, 18). In some specimens
we remark one valve separated so as to expose a dark mass in the hollow of the
other valve (Plate II., fig. 16), which is imbedded in the coal. At other times,
when a section is made of the coal, these sporangia are cut across, and exhibit an

evident cavity (Plate II., figs. 17,18). When thin sections of the coal are viewed
_ by transmittted light, the walls of the sporangia appear of a brownish or orange-
yellow colour (Plate II., fig. 14).

Under the microscope, the valves often present a reticulated appearance, and
minute granular matter seems to be attached to the inner surface. These granules
i suppose to be some of the minute powdery spores slightly altered. It may be

* Geological Transactions, v., p. 485. Plate 38, fig. 9.
VOL. XXI. PART I. . 3 F

192 PROFESSOR BALFOUR ON CERTAIN VEGETABLE ORGANISMS

that the bodies called by some spores, and which exist in many coals, especially
cannel coals, may be the larger spores contained in the other sporangia of this
plant. These fossil spores are large, and appear in the form of a thickened ring,
probably from the pressure to which they have been subjected. Here, then, we
seem to have evidence, that Acrogenous fructification is found in coal, leading to
the conclusion that the plants which produced these sporangia flourished at the
coal epoch, and aided in the formation of this substance.

It is probable also, that the inflammable yellow-brown matter which enters
into the composition of Lycopodes at the present day, and which has caused their
small spores to be denominated vegetable sulphur, may also have been present in
fossil plants of a similar nature, and have contributed to form the yellow substance
which exists in great quantity in some coals,

A substance derived from the organic kingdom also occurs abundantly in the
Fordel coal. This is the resin-like matter called Middletonite. This was seen
about thirty years ago by Dr FLEmtnG,.in the splint coal of Balbirnie in Fife, and
afterwards at Clackmannan. Dr FLEmine is also disposed to think, that certain
veins of a rich wine-yellow, which occur in Boghead coal, contain Middletonite.
This organic substance has been described by Professor Jounston of Durham.*
He found it about the middle of the main coal or Haigh More seam, at the
Middleton collieries near Leeds. It occurred sometimes in small round masses,
but more commonly in fhin layers, scarcely thicker than jth of an inch, between
layers of coal. In Mr Daw’s specimens, the quantity of the substance is very
large, occurring both in layers and in granular pieces, and giving a peculiar rusty-
brown aspect to the surface of the coal. Specimens are seen with several distinct
layers of this substance, separated by thin lamin of coal of about jth of an inch
thick, which also seems to be penetrated by the Middletonite.

Middletonite is hard, brittle, easily scraped to powder by a knife. In small
fragments it is transparent; by reflected light it shows a reddish-brown colour,
by transmitted light a deep-red colour. It has a resinous lustre. It blackens by
long exposure to the air, and then can only be distinguished from the coal by a
slight peculiarity in the lustre. It burns like resin, and leaves a bulky charcoal.

In one analysis, JoHNSTON gives the following composition :—

Carbon, . Ss : 5 : 86°437
Hydrogen, . : : ; ; : 8-007
Oxygen, : . ‘ : ; ; 5563

On examining this substance, and comparing it with the appearance presented
by Lycopode powder, as well as with that exhibited by the inner surface of the
Fordel sporangian valves, I am disposed to hazard the conjecture, that the two
may be closely connected. It seems not improbable, that the inflammable spores

* Brewster’s Journal, xii. (1838), 261.

FOUND IN COAL FROM FORDEL. 198

when acted on by heat and other causes, may have thus formed a continuous
layer of Middletonite in the seams of coal. At all events, the matter deserves
consideration.

In conclusion, I think that this coal gives evidence of Sigillarias and Stigmarias
haying entered into its formation,—of Acrogenous plants allied to Lycopodiaceze
having also been present, as indicated by the abundance of peculiar sporangia,
and of the probable origin of Middletonite from the contents of these sporangia.
In the further prosecution of the subject, it will be interesting to observe if in
those coals which contain Middletonite similar sporangia can be detected.

Explanation of PLATE IL., Figures 5 to 18.

Fig. 5. Punctated woody tissue, apparently coniferous, from the needle-coal of Toplitz in Bohemia ;
from a specimen sent by Professor Harkness (magnified 190 diameters).

Figs. 6 and 7. Dotted or Pitted vascular tissue (Bothrenchyma) from Arniston coal (magnified 190
diameters).

Figs. 8 and 9. Pitted vascular tissue, from Fordel coal (magnified 190 diameters). This kind of
tissue is common in the carbonaceous matter, which is often found between the laminz of
coal and which soils the fingers.

Fig. 10. Pitted vessel from coal with the dots elongated transversely, and giving a scalariform appear-
ance (magnified 190 diameters).

Fig. 11. Scalariform vessels from coal, resembling those of ferns (magnified 190 diameters).
Fig. 12. Seed-like bodies or sporangia, found in vast abundance in Fordel splint coal, natural size.

Fig. 13. The same sporangia magnified about 8 diameters, imbedded in a mass of Fordel coal; some
lying on the surface, others projecting from the broken edges of the coal. They seem to
occur frequently in coal from different localities, both in Scotland and in England. Mr
Biyney has seen them in Wigan coal. Similar sporangia occur in enormous quantity in
specimens of a brown inflammable deposit sent by Sir W. Denison from Van Diemen’s
Land.

Fig. 14. Section of Fordel coal, showing the sporangia as viewed by transmitted light, and magnified
20 diameters. The orange-yellow lines indicate the walls of the sporangia cut across in a
microscopic section.

Fig. 15. Sporangium magnified 20 diameters.

Fig. 16. Valves of sporangium separated, containing a quantity of black carbonaceous matter in its
interior (magnified 24 diameters).

Fig. 17. Sporangium cut transversely, showing the internal cavity (magnified 24 diameters).

Fig. 18. Sporangium cut obliquely, showing the cavity and the dark-coloured contents (magnified
24 diameters).

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XII.— Researches on some of the Crystalline Constituents of Opium. Second Series.
By Tuomas AnpeErson, M.D., Regius Professor of Chemistry in the University
of Glasgow.

(Read 3d January and 1st May 1854.)

In pursuing the investigation of the crystalline constituents of opium, which
formed the subject of a previous communication to this Society, I have succeeded
in obtaining from the same mother liquor which formed the raw material of my pre-
vious researches, a considerable quantity of papaverine, the base recently detected
by Merck, and of meconine, the indifferent crystallizable substance discovered by
CovERBE in the year 1830. The former was encountered quite unexpectedly in
the precipitate from which narcotine and thebaine were prepared by the process
described in the first series of these researches. The latter was only obtained
after many fruitless trials, in which I was induced to persevere by the desire of
comparing it with the substance discovered by myself among the products of the
decomposition of narcotine by nitric acid, and described: under the name of
opianyl. The composition of that substance, as determined by my analyses, ap-
proximates very closely to that of meconine; and though the formula assigned
to the former is double that obtained by CoverseE from his analysis of the latter,
the sole reason for adopting the higher atomic weight was, that the mode in
which opiany! was obtained by the decomposition of narcotine, afforded satisfac-

tory grounds for establishing its true constitution. Nor does their similarity stop
here, for it is at once obvious, on a comparison of their properties, that they pre-
sent many points in common, although even in this respect there are differences
which will be afterwards particularly referred to, much too prominent and im-
portant to be overlooked. Partly on this account, and partly because my pre-
vious investigations of the constituents of opium had shown me that in all other
instances the analytical results arrived at by CovERBE were very far from correct,
I hesitated to assert their identity until I had had an opportunity of submitting
them to an exact comparison, and of repeating the analysis of meconine.

The experiments to be detailed in this paper prove incontestibly that they
actually are identical; and while the composition of meconine is confirmed, the
necessity for doubling its formula is clearly established. <A careful comparison
of the properties of the.two substances has also shown that they are perfectly
alike; but in this respect, and especially as regards the action of various agents
on meconine, the statements made by CovERBE require very material correction.

VOL, XXI. PART I, 3G

196 DR T. ANDERSON ON SOME OF THE

Papaverine.

In the purification of narcotine by repeated crystallizations from boiling alco-
hol, in the manner described in the paper already referred to, the mother liquors
of each successive crystallization had been carefully preserved, and at the conclu-
sion of the investigation they were worked up for the purpose of obtaining the
very considerable quantity of narcotine which they obviously still contained. For
this purpose the fluids were mixed together, and the greater part of the alcohol
separated by distillation. The residue on being left to itself, deposited a con-
siderable quantity of dark-coloured crystals mixed with resinous matters, which
were collected on a cloth and expressed, and the fluid which passed through was
again concentrated and allowed to crystallize, and this was repeated until it
ceased to yield anything on further evaporation. The crystals so obtained were
dissolved in the smallest possible quantity of boiling alcohol, from which they
were deposited in a tolerably colourless state as the liquid cooled. On further
concentrating this mother liquor, and again allowing it to cool, it became
filled with crystals of a substance obviously much more soluble in alcohol
than narcotine, and differing from it in its general characters. It was parti-
cularly observed to restore the blue of reddened litmus, to dissolve readily in
acids, and to saturate them completely; properties not possessed by narcotine.
Its ready solubility in alcohol led at first to the suspicion that it might be the-
baine, which had been already observed accompanying the narcotine, but the
difference in its crystalline form, as well as its complete precipitation from its
solution in acetic acid, by subacetate of lead, proved it to be different. A very
few experiments sufficed to show that the base thus obtained was still conta-
minated with narcotine, from which it might no doubt have been separated by
repeated crystallizations; but as this would have been an extremely tedious pro-
cess, and have caused the loss of a considerable quantity of material, I preferred
a method founded on the marked difference between its basic properties and those
of narcotine. The whole of the crystals obtained from the mother liquors, and con-
sisting partly of narcotine and partly of this other base, were reduced to a fine
powder, and digested with a limited quantity of acetic acid. The acid was ra-
pidly saturated, and as soon as the fiuid had lost its acid reaction it was filtered
from the undissolved portion, which was again treated with the acid; and this
treatment was cautiously repeated as long as it continued to be thoroughly satu-
rated. The solution was then filtered from the undissolved narcotine, precipitated
by ammonia, and the precipitate crystallized from boiling alcohol. The base was
now pure, and analysis showed it to be papaverine, with which its characters were
found to agree in all respects. A consideration of the properties of papaverine
now enabled me to perceive that it must have been present in very large quan-
tity in the mother liquor obtained in the first crystallization of the crude narco-

CRYSTALLINE CONSTITUENTS OF OPIUM. 197

tine, which had not been mixed with the others, but treated in a different man-
ner for the preparation of thebaine, and it seemed probable that it would be
found in abundance in the precipitate produced in that fluid by subacetate of lead.
This opinion proved to be perfectly correct, and after a few trials it was found
that it might be readily extracted in the following manner. The subacetate of
lead precipitate was reduced to fine powder and boiled with alcohol, by which means
a very dark fluid was obtained, which deposited a few crystals, apparently of
narcotine, on cooling, and on further concentration, a dark-coloured resinous sub-
stance was left. After the complete expulsion of the alcohol, the residual mass
was treated with dilute hydrochloric acid, which dissolved narcotine and papa-
verine, and left a quantity of a black resinous matter, which was separated by
filtration. The fluid was then concentrated and left to itself. In the course of
a few days crystals of the sparingly soluble hydrochlorate of papaverine began
to make their appearance, and continued gradually to increase for some time.
As soon as they ceased to increase they were removed from the solution, which
was found to contain narcotine, and purified by several crystallizations. The
base was then separated by ammonia, and obtained in a state of absolute purity,
by solution in boiling alcohol, and crystallization.

Papaverine, as thus obtained, is in the form of minute radiated crystals,
highly soluble in boiling alcohol ; so much so, that a saturated hot solution be-
comes nearly solid on cooling. It saturates the acids completely, and gives in the
most distinct manner the reaction with strong sulphuric acid described by Merckx.
Although the formula assigned to papaverine by its discoverer appeared to be
correct, an analysis of that obtained by the process just described was made; and
as in the course of the investigation it became necessary to ascertain by analysis
whether particular specimens were free of narcotine, several additional combus-
tions were obtained, the results of which arealso given. The analyses were made
with the chromate of lead.

11:020 ... carbonic acid, and

4-250 grains of papaverine, dried at 212°, gave
ie
2°410 ... water.

II. ¢11°714 =... carbonic acid, and
2630 ... water.
4-416 grains of papaverine gave
III. ¢ 11:480 ... carbonic acid, and

2°569 ae water.

4-525 grains of papaverine gave
8°380 grains of papaverine gave, by Pstrcot’s method,
Oao9 *%.., snitrogen,
8-960 grains of papaverine gave, by Peticot’s method,
so0, ..... mitrogen.

198 DR T. ANDERSON ON SOME OF THE

Experiment. Calculation.
ee o——n ne eee
if Il. Ill.
Carbon, : : 70:71 70:60 70:58 TOWO pe 240
Hydrogen, . . 6-29 6-46 6-46 6-20 "©, 21
Nitrogen,* . : 4:40 3°96 he 4:14 N 14
Oxygen, é : 18°60 18°96 ine 18-78 0, 64
100:00 100-00 100-00 339

These results correspond completely with the calculated numbers, and were
sufficient to show that the base is papaverine, but for further security, a determi-
nation of the platinum in its platinum salt was made, with the following results :—

{ 5°684 grains of platinum salt gave
1013 ... platinum=17-82 per cent.
This corresponds with calculated result, which gives 18°10 per cent.

The salts of papaverine having been already sufficiently investigated by Merck,
I did not think it necessary to extend my experiments in this direction, but pro-
ceeded to examine the action of various agents upon the base itself.

Action of Nitrie Acid.

Papaverine dissolves in dilute nitric acid without decomposition, and with the
formation of a nitrate; but if the solution be mixed with an excess of nitric acid,
especially if concentrated, and heat be applied, a brisk action takes place, some
red fumes are evolved, the fluid becomes dark red, and orange-coloured crystals
begin to make their appearance, and gradually increase in quantity. Nothing
can be simpler than the preparation of this substance. The degree of concentra-
tion of the acid is immaterial, for the product is sure to be obtained; and if the
fluid be sufficiently concentrated, crystals begin to be formed the instant the heat
is applied, and soon become so abundant as entirely to fill the fiuid. If the solu-
tion be more dilute, they appear more slowly, and are then larger, more regu-
larly formed, and much paler coloured. The only precaution necessary is, to
avoid the use of too large an excess of nitric acid, as it dissolves the new product
much more abundantly than water. The orange-coloured crystals are the nitrate
of a new base, to which I give the name of nitropapaverine.

Nitropapaverine —is readily obtained from its nitrate, by dissolving it in
boiling water, and precipitating the hot solution by ammonia; but as the salt is
very sparingly soluble, even in hot water, it is more convenient to dissolve it in
nitric acid, and then to add at once an excess of the alkali. A light yellow fioc-
culent precipitate is immediately deposited, which is collected on a filter, dried,

* Merck has published only one nitrogen determination of papaverine, giving 4°75 per cent.,

which greatly exceeds the calculated number. I have observed the same tendency to give an excess,
having in one experiment obtained as much as 4°66. The only mode of explaining this anomaly,

was by supposing that the base carried down a small quantity of the ammonia which had been used

to precipitate it. In order to ascertain whether this opinion was well-founded, a quantity thrown
down by potash was analysed, and the results are those of the second determination.

~

CRYSTALLINE CONSTITUENTS OF OPIUM. 199

and dissolved in boiling alcohol, from which it is deposited on cooling. Nitro-
papaverine is thus obtained in pale buff-coloured needles, insoluble in water, but
soluble in alcohol and ether. It restores the blue colour of reddened litmus, dis-
solves in the acids, neutralizes them completely, and forms a series of salts, all of
which have a pale buff colour and are sparingly soluble in water. When heated,
it undergoes fusion, and at a higher temperature it burns rapidly with a sort of
deflagration. Concentrated solution of potash, when boiled with it, causes the
evolution of traces of a volatile base. It does not give the purple reaction of pa-
paverine with sulphuric acid. Its analysis gave the following results :—

carbonic acid, and

5-065 grains of nitropapaverine, dried at 212°, gave
11-573
2°640 «+ water.

lixperiment. Calculation.
———————— oo _
Carbon, . 5 : 62°31 62°50 Ci, 240
Hydrogen, : ; 5°21 5°20 18 | 20
Nitrogen, : ; bie 7:29 ING 28
Oxygen, . : : Niele 25:01 0-5 96
100-00 384

This corresponds closely with the calculated results for the formula
Cy H,, (NO,) 0,
which is further confirmed by the analysis of the platinum salt given below.
The crystals of the base deposited from alcohol are a hydrate, as indicated by
the subjoined experiment.

i 5:237 grains of nitro-papaverine dried in the air,
{ lost at 212° 0:14 grains = 2°67 per cent.
One equivalent of water requires 2°29 per cent., so that the crystals have the for-
mula C,, H,, (NO,) O, + HO. .

Nitrate of Nitropapaverine.—This salt is obtained by the action of nitric acid
on papaverine, in the manner already described. It appears in the form of four-
sided tables, sometimes of considerable size, and generally of a dark orange colour.
By crystallization from boiling alcohol, it is got in a state of absolute purity, and
then forms fine yellow crystals of great beauty. It is almost insoluble in cold
water, but on boiling it is taken up in somewhat larger quantity, and deposited
on cooling in an imperfectly crystalline form. It is much more soluble in water
containing nitric or hydrochloric acids, as well as in alcohol and ether. When
gently heated it melts, and then deflagrates, leaving a quantity of a nearly black
substance, which burns away completely at a higher temperature. Potash and
ammonia, when digested on it at ordinary temperatures, rapidly separate the base.
The ease with which this substance is formed, and its extreme insolubility render
its production a very useful reaction for papaverine, and by means of it I have

succeeded in proving that this base also occurred in the fluid from which narco-
VOL. XXI. PART I. 3H

200 DR T. ANDERSON ON SOME OF THE

tine was separated by precipitation with ammonia. Nitrate of nitropapaverine is
anhydrous. Its analysis gave these results :—

5°497 grains nitrate of nitropapaverine gave
10°820 ... carbonic acid, and
2°450 ... water.
Experiment. Calculation.
Carbon, . : : 53°68 53°69 Lae 240
Hydrogen, E : 4:95 4:69 F 21
Nitrogen, s ‘ i 9°38 N,, 42
Oxygen, . 3 : ae 32°24 0,5 144
100-00 447

corresponding with the formula
C,, H,, (NO,) O, + HO NO,.

Hydrochlorate of Nitropapaverine—is a sparingly soluble salt, crystallizing
in pale yellow needles. It dissolves readily in spirit, and in excess of hydro-
chloric acid.

Sulphate of Nitropapaverine—is but little soluble in water; it crystallizes in
minute prisms.

Platino-Chloride of Nitropapaverine—is thrown down as a pale yellow preci-
pitate, when bichloride of platinum is added to a solution of the hydrochlorate.
Its analysis gave the following results,—

5°555 grains, dricd at 212°, gave

8245 ... carbonic acid, and

1°900 ... water.

5°579 grains, dried at 212°, gave

0:924 ... of platinum.

Experiment. Calculation.
Carbon, . : 4 40:47 40°66 Cus 240
Hydrogen, X , 3°80 3°55 sr 21
Nitrogen, : ‘ Ls 4°72 5 28
Oxygen, . : : “5 16-26 oc 96
Chlorine, . ; ; 2 18-09 Cl, 106°5
Platinum, : 2 16°56 16°72 Pt 98°7
100-00 590-2

corresponding completely with the formula
C,H, (NO,) 0, HCl + Ptcl.
The rest of the salts of nitropapaverine have not been minutely examined.

Action of Bromine on Papaverine.

When bromine water is added, drop by drop, to a solution of hydrochlorate of
papaverine, a precipitate is obtained which at first immediately redissolves, but
on the further addition of bromine water, at length becomes permanent. It is
the hydrobromate of a derivative base, bromopapaverine.

———

CRYSTALLINE CONSTITUENTS OF OPIUM. 201

Bromopapaverine itself is easily obtained from this substance, by digesting it
with ammonia, and dissolving the product in boiling alcohol. It is deposited, on
cooling, in minute white needles, insoluble in water, but readily soluble both in
alcohol and ether. It dissolves in the acids and forms salts, the greater number
of which are characterized by their sparing solubility. Its crystals were anhy-
drous, and gave on analysis the subjoined results,—

10-845 ... carbonic acid, and
2°330 ... water.
4-780 grains, dried at 212°, gave
9:185 ... bromide of silver.

5168 grains bromopapaverine gave

These results correspond with the formula C,, H,, Br NO,, as is obvious from the
calculation given below.

Experiment. Calculation.
—_—_—_—=
Carbon, : s ¢ 57:23 57°41 C,, 240
Hydrogen, 5:02 4:78 He, 20
Nitrogen, , : oo 3°34 N 14
Oxygen, ‘ : ). 15:34 0, 64
Bromine, . P : 19°45 19°13 Br 80
100-00 4:18

Hydrobromate of Bromopapaverine.—This salt is obtained, as already men-
tioned, by the addition of bromine water to a solution of hydrochlorate of papa-
verine. It varies somewhat in its appearance, according to the degree of concen-
tration of the solution from which it is obtained. If concentrated, it is deposited
with a more or less yellow colour, and is apt to form resinous lumps, particularly
if the bromine water is added rapidly; but when the solutions are more dilute,
it appears in the form of a perfectly white powder. It is well washed with water,
dissolved in boiling spirit, and on cooling is deposited in a state of purity in the
form of a crystalline powder, insoluble in water, and sparingly soluble in alcohol.
When gently heated it melts, and is decomposed. When digested with potash
or ammonia, it is decomposed, with separation of the base. Its crystals are anhy-
drous, and gave the following results on analysis :—

5:647 grains, dried at 212°, gave
10°015 ... carbonic acid, and
Zion ae). Water.
6:398 grains, dried at 212°, gave
4°883 --. bromide of silver.
Experiment. Calculation.
Carbon, . 48:36 48:08" “e940
Hydrogen, 4°35 4-20 isis 21
Nitrogen, 2°80 NW 14
Oxygen, bot 12-85 0, 64
Bromine, 32°48 32°06 Br, 160
100-00 499

202 DR T. ANDERSON ON SOME OF THE

corresponding with the formula
C,, H,, Br NO, + HBr.
Hydrochlorate of Bromopapaverine —is soluble in water, though sparingly.
The rest of its salts have not been examined.

Action of Chlorine on Papaverine.

When a current of chlorine is passed through a solution of hydrochlorate of
papaverine, the fluid becomes brown, and after a time a dirty gray precipitate
makes its appearance, which is insoluble, or nearly so, in water, but dissolves in
boiling alcohol, and gives a resinous deposit as the solution cools. When treated
with ammonia, hydrochloric acid is separated, and a powder is obtained which
is obviously chlorine base. Jt dissolves in the acids, and is reprecipitated by am-
monia. Alcohol takes it up, and deposits it in an amorphous form on cooling or
by spontaneous evaporation. The properties of this substance proving unsatis-
factory, I then tried the action of chlorate of potass added in small successive
portions to a solution of papaverine in excess of hydrochloric acid, but the same
amorphous gray powder being produced, I did not pursue the subject further;
for although one or more derivative bases are unquestionably produced, their
properties are not sufficiently well marked to admit of their proper purification.

Action of Iodine on Papaverine.

When an alcoholic solution of papaverine is mixed with tincture of iodine, and
the solution is left to itself for some hours, small crystals are slowly deposited,
and by further evaporation of the fluid from which they have been removed, ano-
ther substance is obtained.

Teriodide of Papaverine.—To the crystals first separated I give this name.
They are purified by solution in boiling alcohol, from which they are slowly de-
posited in small rectangular prisms. Their colour is purple by reflected, and dark
red by transmitted light. They are insoluble in water, but soluble in alcohol.
It is not acted upon by dilute acids, but ammonia and potash rapidly decompose
it, removing iodine, and leaving papaverine. From this fact it is clear that it is
not the salt of a substitution base, but corresponds in constitution with the
teriodide of codeine, which I described in a former paper.* Analysis gave the
subjoined results :—

8-550 ... carbonic acid, and

7-065 grains teriodide of papaverine, dried at 212°, gave
2°045 ... ‘water.

7°650 grains teriodide of papaverine gave
7°489 ... iodide of silver.

* Edinburgh New Philosophical Journal, vol. 1., p. 103.
g P P

a ae

CRYSTALLINE CONSTITUENTS OF OPIUM. 203

Experiment. Calculation.
Se ee
Carbon, . F ; j 33°02 33°47 Cy, 240
Hydrogen, : : = 3°21 2°92 H,, 21
Nitrogen, ; : : als 1:95 N 14
Oxygen, “ : “ ee 8:95 O 64
Todine, : 5 . 52-90 52°71 I 378
100-00 yay)

The formula of the substance is therefore
Cj El Ig eile

Pentiodide of Papaverine.—By evaporating the mother liquor of the teriodide
this compound is deposited, and is purified from excess of iodine by crystalliza-
tion from alcohol. It then forms slender needles, with an orange colour by trans-
mitted light, and a reddish-bronze surface colour. It is much more soluble in
alcohol than the teriodide, but is insoluble in water. It loses iodine by the ap-
plication of a moderate heat, although perfectly stable at 212°. It is insoluble in
acids, and is rapidly decomposed by ammonia. Its composition was :—

5-502 grains pentiodide of papaverine gave
5:000 ... carbonic acid, and
1:283 °... water.
3°902 grains pentiodide gave
4-665 ... iodide of silver.
Experiment. Calculation.
ee Ee ee
Carbon, , ; s ; 24:78 24-76 or 240
Hydrogen, . é ; ‘ 2°59 2°16 1 21
Nitrogen, . : : , as 1:44 N 14
Oxygen, - : : Ae 6°63 0, 64
Iodine, : : 3 : 64:60 65-01 I, 630
100-00 969

These results give the formula
Cy, Hy, NO, a5 I,.

It is difficult to form a rational conception of the constitution of these sub-
stances. The formule given above seem to be on the whole the most probable;
but it is clear that the analyses admit of a different interpretation, and we may
assume these compounds to be hydriodates with excess of iodine, and represent
their constitution by the formule

C,H, NO, AY + 1,

Ci, NO, an 21,
the additional atom of hydrogen making too small a difference to be important.
We have, however, no experiments to enable us to decide between these two
views, which could only be done by an extended investigation of the similar com-

pounds of the other bases; and in the absence of further information, I have
VOL. XXI. PART I. ‘ 31

204 DR T. ANDERSON ON SOME OF THE

chosen to represent them as iodides, simply because it involves less hypothesis,
and sufficiently expresses their constitution.

Action of Soda Lime on Papaverine.

Papaverine was mixed with about four times its weight of a soda lime, com-
posed of equal weights of its constituents, and the mixture heated in the oil bath.
At 250° traces of a volatile base began to appear, which increased in abundance
when the temperature rose to 300°. After the heat had been continued for some
hours, a small quantity of a pungent base was collected in the receiver. It gave
white fumes with hydrochloric acid, and with bichloride of platinum a highly
soluble salt, precipitated by alcohol and ether in shining plates. A determination
of the platinum in this compound gave the following results :—

5-197 grains platinum, dried at 212°, gave
1-882... platinum.

This corresponds to 36 21 per cent. of platinum, and lies almost exactly be-
tween the numbers required for propylamine and ethylamine, the calculated num-
ber for the former being 37°21, for the latter 35°34. It is probable that the sub-
stance analysed actually contained both bases, but from the small scale on which
it was necessary for me to work, I was precluded from any attempts to substan-
tiate this opinion.

Meconine.

In preparing narceine by the process described in the first series of these re-
searches, I expected to have obtained it mixed with meconine, in the same way
as it had been previously found by CoverBeE and other observers. Much to my
disappointment, however, the narceine proved to be remarkably pure; and even
after one crystallization, ether extracted from it only a minute trace of a resinous
matter, but no meconine. As it could not be doubted that meconine, if present
at all, must still remain in the mother liquor from which the crystals of narceine
had been separated, the fluid was concentrated and left to itself for some time,
but no meconine made its appearance. On further concentration, and standing
for some months, granular crystals were abundantly deposited, which proved to
be nothing but muriate of ammonia, mixed with a resinous matter. Attempts
were then made to remove the amorphous residual matters which abounded in
the fluid, and appeared to prevent the crystallization of meconine, and a variety
of methods were tried to make it deposit crystals, but without success.

After many abortive trials, which it is unnecessary to detail, I found that me-

conine might be easily separated by agitating the fluid with ether. For this purpose

the concentrated fluid was poured into large bottles in which it was mixed with
about a fifth of its bulk of ether. The bottles were tightly corked, set in a warm
place where their temperature was kept at about 80° Fahr., and frequently shaken.

CRYSTALLINE CONSTITUENTS OF OPIUM. 205

- After standing for 24 hours, the ether, which had acquired a brown colour, was
drawn off with a syphon and a new supply added ; and this process was repeated
as long as it continued to extract any considerable quantity. The ether was
then distilled off in the water-bath, and left behind a dark amber-coloured or
brown syrupy fiuid. The first extracts remained thick and syrupy, even after 24
or 48 hours; but those obtained after the agitation with ether had been several
times repeated, occasionally, though not always, became filled with crystals on
standing. On the addition of water, a quantity of a thick resinoid substance, not
unlike turpentine, separated and remained for some time in a semifiuid form at
the bottom of the fluid. When hydrochloric acid was dropped into it, part of the
resinoid matter dissolved, and the rest solidified into a dark-gray crystalline powder,
which was separated by filtration. The hydrochloric solution gave with alkalies a
dirty gray precipitate which soon became resinous on standing, with bichloride
of platinum a yellow, and with corrosive sublimate a dirty white precipitate. It
contained therefore an alkaloid, which was thrown down by ammonia, and purified
by solution in alcohol, in which it was highly soluble, and by boiling with animal
charcoal. It was deposited on cooling in irregular needles, which nearly filled
the fluid, and was shown to be papaverine, by its giving a blue colour with concen-
trated sulphuric acid and orange crystals of nitrate of nitropapaverine with nitric
acid.* The granular precipitate was impure meconine. It was purified by solu-
tion in boiling water, which left a small quantity of an indifferent resin, and the
fluid on cooling deposited an abundance of needle-shaped crystals, still retaining
a yellowish shade of colour, which was easily removed by animal charcoal.

Composition of Meconine.

Meconine has been already analysed by its discoverer CovrerBe, and by
Reenavuut. The earlier analyses of the former} of which the details are not given
in the original memoir, led to the formula C,, H, O,; but as these are admitted to
have been erroneous, it is unnecessary to refer to them further. The results con-
tained in his second memoir,{ and those of Reanavutz,§ are collected in the fol-

lowing table, in which all are recalculated according to the atomic weight of car-
bon now in use.

* Although the salts of papaverine are highly crystallizable and sparingly soluble, the presence
of resinous impurities in the opium fluid has a remarkable tendency to prevent their separating in the
crystalline form; and we see that in this instance a certain quantity of the base had even resisted pre-
cipitation by ammonia. It is probably the same peculiarity which prevents its appearing as an im-
purity in the hydrochlorate of morphia, prepared by the process of Roszrrson and Gregory. The
hydrochlorate of papaverine is less soluble than the hydrochlorate of morphia, and @ priori we should
expect it to be the first substance to deposit from the concentrated fluid, yet the commercial hydro-
chlorate of morphia does not contain a trace of it, the whole being retained in the mother liquor.

+ Annales de Chimie et de Physique, 2d Series, vol. 1., p. 347.

{ Ibid., vol. lix., p. 140.

§ Ibid., vol. Iviii., p. 157.

206 DR T. ANDERSON ON SOME OF THE

COUERBE. REGNAULT.
SSS :.:e——, a
Carbon, . ; . 60:87 61:08 60°86 61°63 61°36 61:22 61:51
Hydrogen, 4 5 5:11 5°54 5:09 5:22 5°40 5°33 5°34
Oxygen, . . 34:02 33°43 34:05 © 33°15 33°24 33°45 33°15
100-00 100-00 100-00 100-00 100-00 100-00 100-00

numbers which agree very well with the formula C,, H, 0,, given for meconine
in the same paper. My own analyses completely confirm these results. The de-

tails are as follows :—

( 5-405 grains of meconine, dried at 212°, gave

I. 12170 ~~... ~—s carbonic acid, and
2-495 ~.... water. :
5-445 grains of meconine, dried at 212°, gave
II.< 12:280 ... carbonic acid, and
2°515 ... water.
Experiment. Calculation.
TT RE A aa
Is I:
Carbon, . ‘ : 61:40 61:50 61:85 Go 120
Hydrogen, : : 5:12 5:13 5:15 aes 10
Oxygen, . : ; 33°48 33°37 33°00 0, 64
100-00 = 100:°00 100-00 194

In the calculated numbers, I have assumed its formula to be the same as that
of opianyl, and it will be immediately shown that the true constitution of both
substances is actually so represented.

Properties of Meconine.

Meconine crystallizes from its solution in water in brilliantly white and very
beautiful needles, which are arranged in branched tufts, in a highly characteristic
manner. Its taste is slightly but distinctly bitter. It is soluble in water, alcohol,
and ether, and its saturated hot solution in the first menstruum becomes filled,
on cooling, with a net-work of crystals, which occupies the whole of the fluid. It
requires for solution 22 times its weight of boiling water, and upwards of 700
times its weight of water at 60°. These numbers differ considerably from those
of CouERBE, who finds it to be soluble in 18°5 parts of hot, and 265 of cold water.
Three careful determinations on solutions made by boiling with excess of meco-
nine, allowing the fiuid to cool, and filtering from the deposited crystals, concurred
in giving the former result; and in this respect meconine completely agrees with

opianyl, which also requires 700 parts of cold water for solution. When dry me-—

conine melts at 230°, and not at 194°, as stated by Covers. It fuses under water
at a temperature of 170°, and it is possible that CovrrBE may have been misled
by this appearance, and determined its fusing point by heating it in water; but

CRYSTALLINE CONSTITUENTS OF OPIUM. 207

there is no statement to this effect in the paper, nor does he mention how that
employed for analysis was dried, so that it is impossible to ascertain how he made
his experiment. When heated to a higher temperature it volatilizes completely,
and is deposited on cooling in fine crystals. If the quantity be large, and the
heat carelessly applied, a trifling carbonaceous residue is left. Meconine does not
appear to dissolve more abundantly in the alkalies than water, and gives no com-
pounds with the metallic oxides. Its effect on subacetate of lead was particularly
examined, but no precipitate could be obtained by any mode of operating. Cov-
ERBE States that he obtained and analysed such a precipitate ; but his description
of the whole reaction is extremely unsatisfactory, his two analyses differ immense-
ly, and there can be little doubt, that the substance he obtained was not a true
chemical compound, but due to some impurity contained in the meconine he em-
ployed. Nitric acid, chlorine, bromine, and iodine, act upon meconine with the pro-
duction of particular compounds, to be afterwards described. When treated in the
cold with concentrated sulphuric acid, it forms a colourless solution, but on gently
heating, a faint purple makes its appearance, which gradually increases in depth,
as the temperature rises, until it becomes so intense, that a stratum of a quarter of
an inch thick is quite opaque ; and at length, if the temperature becomes too high,
sulphurous acid is evolved, and the substance charred. When the purple solution
is diluted with water, a dark-brown precipitate is thrown down, and a brown fluid
obtained. The precipitate dissolves in alkalies, with a fine red colour, and appears
to be a true colouring matter. Exactly the same phenomena are observed when
opiany] is treated in the same manner. CoverBE obtained with meconine, a green
colour, but I have never seen this when it was pure ; although, if it be taken after
its first crystallization, and while still yellow, I have found it to produce a dirty
greenish purple colour, and CovErBer’s results are no doubt to be attributed to
the presence of some impurity.

The observations just made are sufficient to show that meconine and opianyl
are actually identical ; and if further proof be required, it is to be found in the
properties of the substitution products of both substances, to be immediately de-
scribed. It is clear, also, that the discrepancies in the characters of the former
substance as described by myself, and those attributed to meconine, such as its
melting point, precipitation of subacetate of lead and green colour with sul-
phuric acid, which caused me to hesitate in asserting their identity, are due to
erroneous observations on the part of CouERBE.

In what follows, I propose to make use of the name of opianyl, which appears
much more suited to the substance than that of meconine. For some reasons,
perhaps, the name proposed by the original discoverer ought to be retained; but
having been applied to it as an isolated substance, it must be considered as in some
sense as a provisional name, and ought to give way to another, which points out
its relation to opianic acid, and through it to narcotine, from which it can also

VOL. XXI. PART. I. 3K

208 DR T. ANDERSON ON SOME OF THE

be obtained. I shall only employ the word meconine to distinguish that got di-
rectly from opium from that produced by the decomposition of narcotine.

Action of Nitric Acid on Opianyl.

The relation in formule of opianyl and opianic acid led me to anticipate the
easy conversion of the one into the other; but this anticipation has not been
confirmed by experiment. I had immediate recourse to nitric acid, as the
readiest means of effecting the expected change; but in place of opianic acid there
was formed a substitution product corresponding with CovERBE’s hyponitro-
meconic acid, although neither its properties nor the mode of its preparation
agree with his description.

Nitropianyl.—Opiany] dissolves abundantly in cold concentrated nitric acid,
and a few red fumes are given off when heat is applied. On dilution the fluid
becomes filled with bulky crystals, which are obtained pure by washing and so-
lution in boiling spirit. Nitropianyl is obtained in fine white needles and prisms,
sometimes of considerable length. It is very sparingly soluble in cold water,
more so in boiling, and the solution on cooling deposits it in minute crystals. It
is much more soluble in boiling alcohol, and is also dissolved by ether. All these
solutions are perfectly colourless, and absolutely neutral to test-paper. It melts
at 320° into a transparent fluid, which solidifies on cooling into a crystalline
mass. Heated in small quantity on a platinum knife, it volatilizes almost com-
pletely, leaving only a trifling carbonaceous residue; but in a test-tube it decom-
poses suddenly, when the temperature rises to a certain point, leaving a bulky,
porous charcoal. It is not precipitated by metallic salts, and possesses no acid
properties. It does not dissolve in cold potash or ammonia more abundantly than
in water; but on boiling, a larger quantity is taken up, the fluid becomes yellow,
but nothing is deposited on cooling or on the addition of hydrochloric acid, and
the nitropianyl obviously undergoes some change, which deficiency of material
has prevented me from examining. Nitropianyl is insoluble in hydrochloric acid ;
strong nitric acid dissolves it readily in the cold, and deposits it in crystalline
flocks on dilution. When treated with concentrated sulphuric acid the crystals
immediately become yellow, and on the application of heat they dissolve with a
red colour, which becomes more and more intense as the temperature rises. On
dilution with water, the fluid acquires a dirty red colour, which is rendered
darker by ammonia. The analysis of nitropianyl gave the following results :—

5:170 grains of nitropianyl, dried at 212°, gave

9500 ... carbonic acid, and

1640... water.

Experiment. Calculation.
gael eee

Carbon, : ; i 50°11 50°20 Ci 120
Hydrogen, - . : 3°92 3°76 Hi, 9
Nitrogen, 5 . : ge 5°85 N 14
Oxygen, - : : 5 40°19 OF 96

CRYSTALLINE CONSTITUENTS OF OPIUM. 209

This leads to the formula C,, H, (NO,) O,, which is exactly the same as that
of the substance described by CoversBe under the name of hyponitromeconic acid.
This substance, according to CouERBE, is an acid capable of combining with the
alkalies, and yielding precipitates with the salts of iron and copper. It occurs in
long yellow needles, gives yellow solutions with water and alcohol, but not with
ether, and dissolves in the alkalies with a dark yellow, almost red colour, and is
precipitated by acids. It is said to melt at 302°. These characters, though dif-
fering very remarkably from those of nitropianyl, approximate so closely in other
respects that there can be no doubt about the identity of the two substances, al-
though the discrepancies are somewhat puzzling. Some of them may, no doubt,
be explained on the supposition that CovERBE’s substance was impure; but others
scarcely admit of any such explanation. This particularly applies to his descrip-
tion of the mode in which it was obtained. He says that nitric acid is to be boiled
with meconine, and the fluid evaporated to complete expulsion of the acid, and the
residue, on treatment with water, gives hyponitromeconic acid. I found, on the
contrary, that the residue, which represented only a small quantity of the opianyl
or meconine employed, was highly soluble in water, and the solution gave, on
evaporation, an amorphous mass which dissolved in almost all proportions in alco-
hol and ether. In one instance only in which this process was tried, a small
quantity of a crystalline matter was obtained. The soluble substance was not
examined, as its properties were not such as to admit of easy purification. It is
probably a further substitution product.

Action of Chlorine on Opianyl.

When a current of chlorine is passed into a cold saturated solution of opianyl
in water, crystals soon begin to make their appearance, and gradually fill the
whole fluid. In preparing this substance in large quantity, it is convenient to
employ a warm solution, so that the bulk of the fluid may be smaller; but in this
case care must be taken to stop the process before it has gone too far, as the
crystals are apt to diminish, or even disappear, apparently owing to the forma-
tion of a farther product of decomposition, and the same precaution is necessary,
though to a less degree, with the cold solution. The crystals are purified by solu-
tion in boiling alcohol. Chloropianyl may also be obtained by passing dry chlo-
rine over fused opianyl. The gas is rapidly absorbed, hydrochloric acid is evolved,
and the mass becomes gradually less and less fusible, so that the temperature of
the oil-bath in which the tube is immersed must be slightly raised. After the
action has gone on for some time, the current of gas must be stopped and the heat
removed. If the action has been properly managed, the mass is highly crystal-
line, and on solution in boiling alcohol gives crystals identical with those ob-
tained in the wet way. In this case, also, care must be taken to stop the ac-
tion at the proper point, for if it be continued too long, no crystals are obtained,
and the fluid solidifies into a resinous mass _ like Canada balsam.

210 DR T. ANDERSON ON SOME OF THE

Chloropianyl as obtained by either of these processes is in the form of transpa-
rent colourless needles, scarcely soluble in cold water, rather more so in boiling.
Alcohol and ether dissolve it much more abundantly, and deposit it in fine crystals.
It is not more soluble in the alkalies than in water, and they do not remove chlorine
from it. Nitric acid dissolves it with a red colour, and on heating it is decom-
posed. It is soluble in cold oil of vitriol, and on heating, a fine greenish-blue
solution is obtained, from which water throws down brown flocks, soluble in the
alkalies with a red colour. Chloropianyl melts at 347°, and sublimes unchanged
at a higher temperature. The properties of specimens prepared from opianyl and
from meconine extracted directly from opium, were compared, and found to be
perfectly identical. Of the following analyses, the first two were made with
chloropianyl obtained from meconine in the dry way, and the third was from
opiany], and prepared in the wet way.

9-790 .,. carbonic acid, and

5:095 grains of chloropianyl, dried at 212°, gave
iif
1985 ... water.

3°352 grains of chloropianyl gave
TI.< 6-485 ... carbonic acid, and
280"... Water.
4-285 grains of chloropianyl gave
IIl.{ 8:265 ... carbonic acid, and
L620; 3.4 _avater.
4-950 grains of chloropianyl gave
3°039 ... — chloride of silver.
Experiment. Calculation.
ee ———————_—_—_—_————
' i, u. III.
Carbon, . : : 52-40 52°35 52°60 52°51 oom 120
Hydrogen, . 4:32 4-21 4:20 3:93 HH, 9
Chlorine, ; : 15°17 Bia rs 15°53 Cl 35°5
Oxygen, . : . 28°11 eee ey 28-03 0, 64

100-00 10:000 228°5

This corresponds with the formula C,, H, Cl O,.

The action of chlorine upon meconine has been examined by CovERBE, but
his results differ entirely from those just described, and his statements are very
loose, unsatisfactory, and in some points absolutely conflicting. He passed chlo-
rine into fused meconine, and obtained a product containing 25°75 per cent. of
chlorine, and consisting of crystals mixed with a resinous matter. The greater
part of the chlorine exists in the latter, the former containing only 5:43 per cent.,
which is removed by oxide of silver, or by potash. The product is said to erys-
tallize from alcohol in short prisms, to contain no chlorine, but to have a power-
fully acid reaction, and to precipitate the salts of lead and copper. CouUERBE de-
signates it mechloic acid, and assigns to it the formula C,, H, O,,, which ob-
viously bears no relation to that of the original substance, and is in itself impro-

CRYSTALLINE CONSTITUENTS OF OPIUM. 211

bable. The alleged absence of chlorine must also be considered as in the highest
_ degree questionable ; indeed CovErsE appears to have relied entirely on the action
of oxide of silver in removing the chlorine he found in the crude substance, and does
not appear to have tested by heating with lime, and hence has overlooked the sub-
stitution chlorine which his substance undoubtedly contained. Nor is this surpris-
ing, for his paper was written at a time when the law of substitution was un-
known, and little attention had been paid to the organic chlorine compounds.
Ihave already mentioned that ifthe current of chlorine is passed through fused
opianyl for too long a time, no crystals are deposited, and a substance resembling
Canada balsam is obtained, which is no doubt identical with the resinous matter
which CovEerBe got mixed with the crystals of his mechloic acid. This substance
is insoluble in water, but highly soluble in alcohol and ether, and deposited in an
amorphous condition when these menstrua are evaporated. When treated with
potash it dissolves, and the fluid on saturation with an acid yields a pulverulent
precipitate, soluble in alcohol, and giving irregular crystals on evaporation. This
substance | at first suspected might be mechloic acid, but it is entirely different,
contains abundance of chlorine, and is obviously a further substitution product,
although it was not obtained of definite constitution. A single analysis gave—

4-540 grains, dried at 212°, gave
8-295 ... carbonic acid, and
1:5385 ..... water.
Carbon, : ‘ F 45°82
Hydrogen, . : ; 3°79

This lies nearly half-way between the numbers of chloropianyl and those re-
quired for a product containing two equivalents of chlorine.

_ CovErBE gives for his resinous substance the formula C,, H, O,; but if we as-
sume it to have contained chlorine, his analysis would agree pretty well with
the formula C,, H, Cl, O,. His numbers, recalculated with the correct atomic
weight of carbon, are given below, and compared with that formula.

CouUERBE, Calculation.

n —_——————S__— ————=— -
Carbon, 3 : . 46:93 45:53 45°63 C;, 120
Hydrogen, . . . 3:72 3°83 3:04 i; 8
Chlorine, : ; 3 +7 aah 26:99 Cl, Ga
Cee ar (Siew mk tiuuge ose ef 2434 =O, 64

100-00 268

It is highly probable that this substance actually did contain chlorine, but the
approximation to the formula is possibly only fortuitous.

Action of Bromine on Opianyl.

When bromine water is dropped into an aqueous solution of opianyl, crystal-
VOL. XXI. PART I. 3 L

212 DR T. ANDERSON ON SOME OF THE

line flocks of bromopiany! are immediately deposited, which are purified by solu-
tion in boiling spirit. Bromopianyl is thus obtained in colourless transparent
needles, very sparingly soluble in water, much more so in alcohol and ether. It
is rather more fusible than chloropianyl, its melting point being 332°; but in its
general characters and relations to acids and bases it is so similar to that sub-
stance that the same words may serve to describe both. Its analysis gave—

8202 ... carbonic acid, and

5:105 grains of bromopiany], dried at 212°, gave
L565... J... | water.

4-200 grains of bromopianyl gave
2883 ... bromide of silver.

Experiment. Calculation.
oe ee. ES
Carbon, . . 5 : ; 43°81 43-95 Coa 120
Hydrogen, ; . ; . 3840 3°29 Hy 9
Bromine, : : F 5 IDA 29°30 Br 80
Oxygen, . ; : : - 2358 23°46 0, 64
100-00 100-00 273

corresponding with the formula C,, H, Br O,.

Action of Chloride of Iodine on Opianyl.

Iodine, whether in solution in alcohol or in the solid form, is entirely without
action on opianyl. I therefore tried whether the ingenious process described by
Mr Brown for causing the substitution of iodine for hydrogen would succeed in this
case, and the experiment proved completely successful, although the change was
very slowly effected. When chloride of iodine was added to an aqueous solution
of opianyl, no crystals were deposited at first, and the fluid retained its colour.
It was placed upon the sand-bath, in a moderately warm place, where it was left
for several days, at the end of which time crystals of an inch in length, and mixed
with some iodine had deposited. The crystals were separated, and dissolved in
boiling alcohol, which deposited them pure and colourless.

Iodopiany] is obtained in colourless needles of considerable size and great beauty,
which are scarcely soluble in water, but dissolve in alcohol and ether. At 234°
it fuses to a colourless liquid, which soon becomes brown, and at a higher tem-
perature it is decomposed and iodine evolved. Nitric acid destroys it, with sepa-
ration of iodine. Sulphuric acid dissolves it, and on heating a dark colour is
produced. Its analysis gave

9530 ... carbonic acid, and

6°993 grains of iodopianyl gave
1-865 .,. water.

4-735 grains of iodopianyl gave
3-460 ... iodide of silver.

CRYSTALLINE CONSTITUENTS OF OPIUM. 213

Experiment. Calculation.
Carbon, . : PP 3736 37°48 C5 120
Hydrogen, : : 2 )(2796 2°81, lee 9
Todine, : 4 ; woos 39°70 i 127-1
Oxygen, . ; : . 20°40 20°01 OF 64
100-00 100-00 3820°1

The formula is therefore C,, H, 10,.

Action of Peroxide of Lead and Sulphuric Acid on Opianyl.

I had fully expected that either opianic or hemipinic acids would have been
produced by the action of nitric acid on opianyl; but having failed to obtain them,
I had recourse to peroxide of lead as a convenient oxidizing agent. When opianyl
is heated very gently along with that substance and sulphuric acid, an action
takes place, carbonic acid is evolved, and an amorphous substance obtained in
solution. Deficiency of material, however, prevented the extension of my expe-
riments in this direction as far as was desirable; but having recently contrived a
process by means of which opianyl may be obtained with great certainty from
narcotine, I hope to return to the subject ina future paper. There can, I think,
be no doubt that by the use of an oxidizing agent incapable of producing a sub-
stitution product, one or other of these acids must be obtained.

The preceding experiments having established the identity of meconine with a
decomposition product of narcotine, it seemed natural to suppose that the former
was not an original constituent of opium, but had been produced by the decom-
position of the latter, either during the process of inspissation, or in the chemical
treatment to which it had been submitted; and in that case, the mother liquors
from which it was extracted ought also to contain cotarnine. As that base is not
precipitated by ammonia, the probability was, that if present at all, it must have
existed in the fluid along with opianyl, and ought to have been extracted from it
| by ether, but no satisfactory evidence of its presence could be obtained, the only
| basic substance contained in the ether, being the small quantity of papaverine
which was separated in the manner already described. Nor can this excite sur-
prise, for the difficulty there is in making cotarnine crystallize under any circum-
stances, and the extent to which its properties are masked by the presence of
other substances, are such as almost to preclude the hope of extracting it from
the large mass of indeterminate amorphous substances with which it must be
mixed. Resinous matters possessed of basic properties, and giving precipitates
with bichloride of platinum, and corrosive sublimate, were found along with the-
) baine, and abound in all parts of the opium mother liquor; but no special attention
| was paid to these, very few trials having shown that their purification would have
been attended with great difficulties. It is possible that cotarnine may exist in
some of them.

214 ' DR T. ANDERSON ON SOME OF THE

The relationship thus brought out between two substances which have
been long described as isolated constituents of opium is entitled to much con-
sideration, and is the first step towards the simplification of the chemistry of
a substance so remarkable for its complexity. As a matter of speculation, the
opinion has long been entertained, that when several well-defined substances exist
in the same plant, they must bear some relation to one another, and it has not
unfrequentlyhappened that this idea has been borne out by the formule assigned
to them. Quinine and cinchonine, which were once supposed to differ only in the
proportion of oxygen they contain, may be cited as striking instances; and it was
commonly believed that these two substances must be related in the same man-
ner as two different oxides of a metal, and by the proper use of oxidizing and
reducing agents must be mutually convertible. But neither in this nor in any
similar instance has the anticipated conversion been realized, except with harma-
line and harmine, the two bases of .the Peganum harmala, and it is somewhat
remarkable, that theformer is converted into the latter by the oxidation of two
equivalents of hydrogen, exactly as I have found to occur with narcotine, except-.
ing that there is no splitting up into two products, as with the latter substance.

But although the conversion of other alkaloids has not hitherto been success-
ful, there cannot be a doubt that the close approximation in the formulee of sub--
stances occurring in the same plant, indicates some natural connexion, and it is
important that all such relations, where they exist, should be kept distinctly in
view. For this reason, I propose to direct attention to those which have been
brought out by the investigation of the compounds of opium.

Between the two best known of these alkaloids, morphia, and codeine, a very
simple relation subsists. Their formule are,

Morphia, , A . Cee N 0,
Codeine, , ‘ 2 g Oy, dies an,
Difference, ; Coes

and their relation is that of the two immediately adjoining members of a homo-
logous series. Yet there is little, if anything, except their formulze, to bear out’
the opinion that they actually are homologous. They show but little of that close-
similarity in properties, which frequently renders the separation and distinction
of such substances so difficult ; and especially in their relations to solvents, there.
are very marked differences. Still the connexion is worthy of mention ; the more
especially, as the experiments of Mr How* lead to the opinion that they are both
nitryl bases.

Thebaine and codeine are likewise somewhat closely connected,—

Thebaine, . i F : €,, dep NO:
Codeine, : c ? . Co tls, NO,
Difference, : C,

* Quarterly Journal of Chemical Society, vol. vi., p. 125.

CRYSTALLINE CONSTITUENTS OF OPIUM. 215

The difference is here only two equivalents of carbon ; but at present we know too
little regarding the former base, to permit more than a simple reference to this
difference. Again, comparing thebaine with papaverine,—

Thebaine, . : < ‘ Cig Hla OR
Papaverine, : : : C7), HR N@;
Difference, i C O

we find them to differ by the elements of two equivalents of carbonic oxide.

Passing from these, which may be considered as forming a group of substances
closely allied, at least in formule, to one another, we come to other bases nearly
related among themselves, but which cannot be connected in any simple way
with those just mentioned. Narcotine and narceine deserve the first notice.

Narceine, . : : : C,, H,, NO,,
Narcotine, . ; : : Cie Hy, NO;,
Difference, ‘ H O

4 4

They differ, therefore, by four equivalents of water only, and narceine might
be considered as a hydrate of narcotine. It appeared to me that it must be easy
to ascertain whether the molecular condition of narceine admits of this construc-
tion; for in that case, it might be expected to undergo decompositions similar to
those of narcotine. I accordingly tried the action of nitric acid upon it, but there
was no production of opianyl or cotarnine, and though the decomposition was
not followed up, enough was seen to lead me to the inference that most pro-
bably a substitution base was produced.

It is scarcely necessary to refer to the constitution of narcotine, and its rela-
tion to opianyl, further than to observe, that in my former memoir I have as-
sumed it to be produced by coupling cotarnine with a substance, C,, H,, O,, to
which I have given the name of hydruret of opianyl. I recur to it here, because
I am inclined to think that opianine is similarly constituted, although it must be
admitted, that the unsatisfactory and incomplete information we at present
possess regarding that base gives the opinion I am now about to hazard a some-
what speculative character.

HINTERBERGER,* in his preliminary notice announcing the discovery of opian-
ine, assigned to it the formula C,, H,, NO,,, which is altered in the published paper}
to C,, H,, N, O,,. The difference between these two statements is attributed by
HINTERBERGER to his having at first employed VarRENTRAP and WILL’s method
of determining nitrogen, by which only half of that element is separated in the
_ form of ammonia, and he consequently obtained only 2:22 per cent. of nitrogen ;
| but in subsequently repeating its determination by Dumas’s method, he obtained

* Annalen der Chemie und Pharmacie, vol. Ixxvii., p. 207. Tt Ibid., vol. lxxxii., p. 320.
VOL. XXI. PART I. 3M

216 DR T. ANDERSON ON SOME OF THE

twice that quantity. If this be the case, opianine must be a base entirely unique
in its properties; for in all the fixed alkaloids hitherto examined, the whole of the
nitrogen is converted into ammonia with the utmost facility by ignition with
soda lime. On this ground alone I should be inclined to question the accuracy
of HINTERBERGER’s results; and these doubts are increased by a more minute
examination of his analyses. In two determinations by Dumas’s method, he ob-
tains 4:12 and 4°41 per cent. of nitrogen, while the calculation for his formula
requires 4°45. Now it is a familiar fact, that, owing to the impossibility of re-
moving the last traces of atmospheric air from the tube, the determination of
nitrogen as gas invariably gives a larger quantity than theory requires, so much
so that an excess of a half per cent. is not uncommonly met with, even in the hands
of the most careful experimenters. But in both of HINTERBERGER’s experiments, the
quantity falls short of theory, and in one of them to the extent of about 0:4 per
cent. Partly on this account, and partly because his formula is at variance with the
law of the divisibility of formule, I incline to the opinion that it cannot be cor-
rect, and that in all probability his first nitrogen determinations are more accu-
rate, and to them I shall adhere. The details which HINTERBERGER has supplied
us with regard to opianine and its salts are extremely meagre, and do not afford
very decided grounds on which to found a formula; but weighing them all,
the constitution of opianine appears to be best represented by C,,H,, NO,,. That
this formula would agree almost as well with HINTERBERGER’s experiments as
that he has himself given, is at once obvious from the following comparison, in
which all his results excepting the nitrogen determinations are contained.

Opianine.
Experiment. Calculation.
Cos H, N, 02; Coe H,, NO,,
Carbon, 62-99 63:06 63°56
Hydrogen, 5-69 5°73 5:93
Nitrogen, ste 4:45 2:24
Oxygen, 27°76 28°27
100-00 100-00
Mercury Compound of Opianine.
Experiment. Calculation.
Cee Hy, N, 02, Cog H,, NO,,
Carbon, : 49:14 9-50 49:81
Hydrogen, . 4°60 4°63 4°77
Nitrogen, a 3°50 1-76
Oxygen, me 21:00 22°16
Chlorine, 9°31 8-87 © 8:93
Mercury, 12°28 12°50 12°57
100-00 100-00

CRYSTALLINE CONSTITUENTS OF OPIUM. 247

Now if this be its formula, we have only to subtract from it an equivalent of hy-
druret of opianyl to have narcotine.

Opianine, . : ; C,, Hj, NO,
Hydruret. of opianyl, Cas IL, 0,

Narcotine, : Cie roe NO
And pursuing this point, we should develop a remarkable relation between these
two bases and narcogenine, for all these would be compounds of cotarnine and
hydruret of opianyl! in different proportions, as thus represented :—

Opianine, : : ; Could On = oC ne Hig Oe 12 (C,4 4 Op)
Narcotine, . : . (igen Abn Ua C,. ines _N 0, Se Clas HL, O
Narcogenine, : : 2 (C,, H, ; NO, i= 2(C,, HL, aN 0, gt C, Ae ° 0,

The possibility of representing narcotine and narcogenine in this manner
has been already suggested by WeRTHEIM,* and derives great support from the
researches contained in this and the previous paper; and should the view
I have taken of the constitution of opianine be confirmed, these three will
form a very remarkable and important group of bases. I have had no oppor-
tunity of examining Egyptian opium, from which alone opianine is obtained, and
have been unable to submit my view to the test of experiment, but I have thrown
it out as deserving the attention of any one who may have occasion to re-examine
that substance.

The following is a table of the compounds analyzed in this paper :—

. Papaverine, . ; : : ; - Ci grea NO,
Nitropapaverine, - ; : : - C, i at Pat ist 0 ») NO,
Nitrate of Nitropapaverine, : : : Cre een O,) NO, +HO NO,
Platinum salt of papaverine, . : ‘ C, AEE (NO,) NO, HCl Pt+ ‘ce
Bromopapaverine, . - ‘ 4g ddan Br NO;
Hydrobromate of bromopapaverine, : : Ci, H, » Br NO, +H Br
Teriodide of papaverine, . : : ; Ci, Hie NO, + 1,
Pentiodide of papaverine, : . ©, , NOj+ 1
Opianyl (meconine), : : : OF Os
Nitropianyl, . : : : : ; CH. (NO,) 0;
Chloropianyl, : 2 Cre Cr O;
Bromopianyl, : , : : ORR 5 Rs) OR
Iodopianyl, . ’ : : : - C7, ate LO,

In conclusion, I may state that in pursuing the investigation of the compounds
of opium, I have ascertained that by treatment with sulphuric acid, opianic acid
is converted into a true colouring matter capable of giving, with iron and alum
mordants, all the colours produced by madder; and taking into consideration
that the formula of alizarine, C,, H, O,, differs from that of opianic acid by the
elements of four equivalents of ie sli I think it is not impossible that the
‘ew colouring matter may actually prove identical with it. Should it do so,

* Annalen der Chemie und Pharmacie, vol. Ixx., p. 71.

218 ON SOME OF THE CRYSTALLINE CONSTITUENTS OF OPIUM.

a very important and remarkable relation would be brought out between madder
and opium. At the same time I must mention that my experiments are not as
yet sufficiently advanced to enable me to speak with any degree of certainty on
this point. I have also ascertained that apophyllic acid is an acid methylamide
corresponding in its constitution with oxamic and tartramic acids, but contain-
ing methylamine in union with a non-nitrogenous acid. I have likewise contrived
a process by which opianyl can be obtained from narcotine by a different decom-
position from that described in my former paper, and with absolute certainty.

The full details of these and other matters required to complete the history
of these compounds, I must reserve for a future paper.

(219)

XIII. — On the Products of the Destructive Distillation of Animal Substances.
Part III. By Tuomas Anprrson, M.D., Regius Professor of Chemistry in
the University of Glasgow.

(Read 17th April 1854.)

In the preceding parts of the investigation of the products obtained by the
destructive distillation of animal substances, I have entered fully into the method
of treating the raw material, and have shown the existence in it of not less than
three different series of bases; one, that of which methylamine is the type; a
second, of which picoline is an example; and a third series, not yet further exa-
mined, to which the provisional name of pyrol bases has been applied. Besides
these, aniline is also met with, but whether as an isolated substance or accompa-
nied by the other members of its series, cannot be determined, as none of them
possess sufficiently distinctive reactions to permit their detection in a complex
mixture.

To the series of which picoline is a member my attention has hitherto been
specially directed, and chiefly owing to the interest attaching to these bases from
their identity in composition with the corresponding members of the aniline series,
aniline and picoline being the first instance in which the isomerism of two organic
bases, of which we have now so many examples, was distinctly made out. In
the second part of the investigation, three members of the series in question are
described, namely—

Pyridine, : : : : : Codie ON’
Picoline, , ‘ : : ; C,, H, N
Lutidine, 2 : : : ; Cie

of which the two latter are isomeric with aniline and toluidine. It was further
remarked, that the phenomena observed seemed to indicate that the members of
this series present in Dippel’s oil, did not terminate with lutidine, but that bases
of higher atomic weight and boiling point manifestly existed in it. The object of
the present paper is to show that this statement was well founded, by giving a
description of another member of the series, and further to define their true con-
stitution.

On pursuing the distillation of the different fractions of basic products obtained
by the process described in the second part of this investigation, and distilling at
temperatures above 305°, which is about the boiling point of lutidine, it was found
that, when converted into platinum salts, the percentage of platinum gradually

diminished as the boiling pointrose. Taking advantage of the well-known empirical
VOL. XXI. PART I. 3 N

220 DR T. ANDERSON ON THE PRODUCTS OF THE

law that the boiling points of homologous substances rise by 34° of Fahrenheit
for every addition of C, H, to the atom, and from which the boiling points of
pyridine, picoline, and lutidine do not greatly differ, I directed my attention to

the portion of mixed bases boiling about 340°, in which it was reasonable to ex-

pect that the next base of the series should be found. But even after repeated
rectifications, the base distilling at this temperature still gave a very powerful
reaction of aniline, with chloride of lime, and the percentage of platinum in its
double compound was but little lower than that of the lutidine salt, or at all
events never reached the number required by theory for the higher base. Being
convinced that the separation of two bases approximating so closely in their boil-
ing points as aniline and the substance I expected to find, could not be effected
by fractionated distillation, or at least only by an expenditure of time, labour, and
material, altogether out of proportion to the importance of the object to be at-
tained, I endeavoured to accomplish it by crystallization. Having observed that
the other members of the picoline series gave highly soluble and even deliquescent
oxalates, I conceived that by converting the mixed bases into salts of that acid, it
would be easy to separate the rather sparingly soluble and highly crystallizable
oxalate of aniline, and obtain the oxalate of the other base in a state of purity.
But this expectation was not confirmed by experiment; for neither from the por-
tion boiling about 340°, nor even from that collected at 360°, and corresponding,
therefore, with the boiling point of pure aniline, could the slightest trace of crys-
tallized oxalate of aniline be obtained, although both fractions gave the reaction
of that base in the most powerful manner. The experiment was varied in every
possible way, by the use of water, spirit, and absolute alcohol, but by allowing
these fluids to evaporate spontaneously only a thick syrup was obtained, without
the slightest indication of crystallization. Even the addition of ether to its alco-

holic solution gave only a syrupy fluid, and no crystals; and I was forced to con- _

clude, that even in the portion of the mixed bases corresponding to the boiling
point of aniline, its quantity was so small in proportion to the other substances,
that the properties of its salts were entirely masked by them.

Not succeeding in obtaining the pure aniline, and so separating it from the other
base, the question came to be, how to get rid of the former substance in the best
possible way. For this purpose I availed myself of the extreme stability of the
bases of the picoline series mentioned in my former paper, which is so great that
they resist even the action of strong nitric acid, by which aniline is entirely de-
stroyed. When the base, boiling between 340° and 345°, is mixed rapidly and in
large quantity with nitric acid, much heat is evolved, and a brisk action takes place;
and if the portion boiling about 360° is employed, the action is so violent as to be
almost explosive, and it is requisite to add the base drop by drop to the acid, which
must be kept carefully cool. The acid fluid acquires a deep red colour, and on boil-
ing, red fumes are abundantly evolved, accompanied by an odour resembling that of

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 221

bitter almonds. After the action has ceased, the fluid becomes muddy when
mixed with water, and a thick reddish-yellow oil is deposited, which has exactly
the odour of nitrobenzide, and resembles it in many of its properties. The quan-
tity of this substance produced is by no means large, and it is evidently mixed
with some resinous substance. Owing to this circumstance I have not been able
to submit it to purification and analysis, so as to ascertain whether it really is
nitrobenzide; but though that substance has not yet been obtained by a similar
action on pure aniline, it is quite possible that it may be produced, and the reason
why it has not hitherto been observed, is probably because no one has had occasion
to sacrifice large quantities of aniline inthis manner. The acid solution of the un-
decomposed base is passed through a wet filter, in order to separate the oil, and the
fluid boiled for some time to expel the last traces. On saturation with potash,
and distillation, an oily base passed over with the water, and collected on the
surface. This base, on being converted into a platinum salt, was found still to
give a result greatly above that required by theory for the substance of which I
was in quest. On submitting it to distillation, it was found to commence boiling
at about 320°, and hence to contain a large quantity of lutidine; and it was only
the very last portion which gave a platinum salt corresponding with theory. It
| was clear that a large quantity of lutidine had been retained at a boiling point
above that which naturally belonged to it, by the presence of aniline, and that
| substance being destroyed, it came over at its natural boiling point. The higher
fractions of the oil containing aniline were therefore treated in a similar manner,
and the undecomposed bases, which amounted to from a half to two-thirds of the
- original quantity acted on by nitric acid, were submitted to fractionated distillation.
| The product was found to spread over a considerable number of degrees, and a
| quantity of that collected between 340° and 345° was converted into a platinum
_ salt and analysed, but the results indicated the presence of much lutidine.
The product being still obviously impure, was submitted to a systematic frac-
| tionation, and it was observed that the thermometer remained remarkably steady
about 354°. The portion boiling between 350° and 360° was collected apart, and
| after several rectifications, a fraction was obtained, which distilled entirely be-
| tween 352° and 356", and proved to be the pure base, to which I gave the name
| of collidine.

Collidine.

Collidine is obtained in the form of a transparent and colourless oil, which may
| be preserved for a long time in bottles only partially filled with it, without acquir-
ing colour. A rod dipped in hydrochloric acid brought in contact with it, gives
| abundant white fumes. It is insoluble in water, and floats on its surface, with-
| out undergoing diminution. It dissolvesa small quantity of water, which is readily
| separated by caustic potash. It is highly soluble in alcohol, ether, and the fixed

222 DR T. ANDERSON ON THE PRODUCTS OF THE

and volatile oils. It dissolves with great facility in the acids, but even when added
in large excess, it does not neutralize them. It precipitates alumina, chromium:
zinc, and peroxide of iron from their solutions, but gives no precipitate with baryta,
lime, magnesia, manganese, or nickel. It throws down oxide of lead from the
nitrate, but not from the acetate, a remarkable peculiarity, which it shares with
methylamine and ethylamine. With corrosive sublimate, it forms a double salt,
but from salts of the suboxide of mercury, it throws down the oxide. Its odour
is strong, aromatic, and far from unpleasant. Its specific gravity is 0-921, and it
boils at 354°. The following results were obtained by analysis,—

4-075 grains of collidine gave
I. ¢ 11-800 ... ¢arbonic acid, and
3450 | ... water.
4-079 grains of collidine, gave
II.< 11:800 ...__—_ carbonic acid, and
3°393 ° .... Water.
4:124 grains of collidine, gave
IiI.; 11.980 ... carbonic acid, and
3°60 =...‘ water.
Experiment. Calculation.
i II. Ill.
Carbon, : : 78:97 78°89 19°22 79°33 Ci. 96
Hydrogen, . : 9°40 9:24 9-58 9-09 oe 11
Nitrogen, . ; 11:63 11:87 11-20 11:58 N 14
100:00 100-00 100-00 100-00 Le

These numbers correspond with the formula C,, H,, N. Collidine forms, there-
fore, another member of the picoline series, and corresponds in constitution
with the base described by Canours, under the name of zylidine, in the aniline
series; with which, however, it is isomeric only, and not identical, its properties
being different in all respects.

The salts of collidine are, for the most part, highly soluble and deliquescent.
When evaporated, they form uncrystallizable gummy masses, some of which, on
standing, show traces of crystallization. They are soluble also in alcohol, but
not in ether. The only highly crystallizable compounds, are the mercury and
platinum double salts.

The mercury double salt is thrown down in the form of a curdy white preci-
pitate, on the addition of a solution of corrosive sublimate to a solution of the
hydrochlorate of collidine. It dissolves in boiling spirit, and is deposited, on cool-
ing, in needles. It could not be obtained of definite composition.

Platinochloride of Collidine—is obtained, when strong solutions of hydrochlo-
rate of collidine and bichloride of platinum are mixed. It is slowly deposited in
the form of orange-yellow prisms or needles, according to the degree of concen-
tration of the fluids. It is readily soluble in water, but insoluble in alcohol and
ether. Its analysis gave the following results,—

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 223

6°345 ... carbonic acid, and

6-013 grains of platinochloride of collidine gave
I.
PO Sins 4 ones LWateks -

5-040 grains of platinochloride of collidine gave

TI. 5:°360 ... ~— carbonic acid, and
1650 7%.. "water.
I 5-620 grains of platinochloride of collidine gave
"11-705 ... “platinum,
rr, { 4535 grains of platinochloride of collidine gave
Sil 362) J in.. » platinnn,
5:097 grains of platinochloride of collidine gave
10M .
1657. ..._~—~platinum,
Experiment. Calculation.
ae a eS
I. nig III.
Carbon; ws. 28*7T 29-00 “ 29:33, €,,,. 96
Hydrogen, . : 3°57 3°63 oo 3°66 oP 12
Nitrogen, nee ike oe 4°31 N 14
Chlorine, . : sity a a 32°54 Cl, ~ 106*5
Platinum, . : 30300 80:03 29°89 30°16 Pt 98-7
100-00 327°2

These results correspond with the formula C,, H,, N HCl PtCl, and entirely con-
firm the constitution of the base. The rest of its salts have not been particularly
examined, as they did not present anything of interest.

Constitution of the Bases of the Picoline Series.

Having in this and the previous part of these researches, accumulated sufficient
evidence of the existence of a class of bases isomeric with that of which aniline is
the type, it became important to determine to which of the three classes of volatile
bases they belong. For this purpose, pyridine, picoline, and collidine, were sub-
mitted to the action of iodide of ethyl. The experiments were carried out in
considerable detail with picoline, but with the other two salts, no more was done

than sufficed to substantiate the fact, that iodide of ethyl acted on them in a
similar manner.

Action of Iodide of Ethyl on Picoline. °

_ Anhydrous picoline and iodide of ethyl were mixed, in the proportion of one
volume of the former to two of the latter, and sealed hermetically in a combustion
tube. The two fluids mix readily, but if the tube containing them be gently
heated, by plunging it for the space of half a minute into the water-bath an action
takes place, attended with the evolution of much heat, the fluid becomes muddy,
and separates into a thick oily stratum, which rises, to the surface, and a more
fluid one, which descends. On cooling, the former solidifies into a highly crystal-
line mass, and well-formed crystals appear in the latter, which consists of the

excess of iodide of ethyl. Even without the application of heat, the action takes
VOL. XXI. PART I. 3 0

224 DR T. ANDERSON ON THE PRODUCTS OF THE

place, though more slowly, and it is necessary to have them in contact for some
days before the action is finished. When heat is applied, the action is complete
in ten minutes, but in every instance the tubes were allowed to stand for twenty-
four hours, so as to present the complete crystallization of the new compound.
The tubes were then opened, the whole contents thrown upon a filter, and the
crystals slightly washed with a mixture of alcohol and ether, pressed between
folds of filtering paper, and dissolved in the smallest possible quantity of a mixture
of boiling alcohol and ether. On cooling, the new substance is deposited in beauti-
ful silvery plates. It is highly soluble in water, and though not deliquescent, it
becomes slightly damp in moist air. Its aqueous solution, on evaporation, solidi-
fies into a mass of crystals. It is readily soluble in alcohol, especially when boil-
ing, and the hot solution on cooling becomes filled with crystals. It is less soluble
in ether. It fuses below 212° into an oily fluid. Its analysis gave these results,

5359 grains dried in vacuo, gave
7570 ... of carbonic acid, and
2°375 ... water.
6-440 grains, dried in vacuo, gave by direct precipitation
6:065 ... iodide of silver.
Experiment. Calculation.
a
Carbon, 2 : : 38°57 38°70 Gg teae
Hydrogen, . ; - 4:93 BOS Bags, Le
Nitrogen, . : : 5°61 5°67 N 14
Todine, : ; F 50°89 50°80 I 126
100-00 100-00 248
These results agree with the formula C,, H,, N HI, which is that of hydriodate of

ethylopicoline.

On the addition of a few drops of caustic potash to the solution of this salt,
no odour of a volatile base evolved, nor is there any separation of an oily layer,
but the addition of a large quantity of strong potash, causes the precipitation of
a viscid oil, which solidifies on standing for some hours into a mass of crystals,
generally much coloured, and which proves to be the hydriodate partially altered
by decomposition. When boiled with strong potash, a volatile base is slowly
formed, which is a product of decomposition, and will be afterwards referred to.
From these characters it is obvious, that ethylopicoline belongs to the ammonium
class of bases, and hence, picoline itself, must be a nitryl base; and this being
the case, the formula of the iodine compound might be written thus, C,, H,, N+I,
representing it as the iodide of a base corresponding to ammonium, of which the
constitution must be C,, H,, N, and whose oxide, C,, H,, NO, must exist in its
oxygen acid salts. If we adopt the nomenclature proposed by Horrman for the
ammonium bases, we should have a very clumsy name for this substance, and I
shall therefore continue to call it ethylopicoline, which, though not perfectly
correct, is sufficiently distinctive.

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 225
Ethylopicoline, or rather its oxide, is readily obtained, by agitating the aque-
ous solution of the iodide with moist oxide of silver, when iodide of silver is pre-
cipitated, and the base obtained in solution. In performing this process, heat
must be avoided, as oxide of silver decomposes the base at a high temperature,
fine violet streaks appearing in the fluid, which rapidly acquires a deep crimson
colour. The same change occurs, though more slowly, in the cold, especially if
the oxide of silver be added in large excess, and it is therefore desirable, that the
solution should be separated as rapidly as possible. If this be done, a colourless
solution is obtained, having a faint peculiar odour, and highly alkaline properties.
It restores the blue of reddened litmus, and gives an intense brown with turmeric ;
it has a powerfully caustic taste, and produces a soapy sensation when rubbed
between the fingers. It absorbs carbonic acid from the air, precipitates alumina,
and redissolves it when added in excess. From a solution of corrosive sublimate
it throws down the oxide, and with the metallic salts generally, it reacts in pre-
cisely the same manner as potash or soda. On boiling, its solution acquires a
deep red colour, and the odour of a volatile base becomes apparent. By evapora-
tion in vacuo, ahard gummy mass, with a green metallic lustre is left behind,
which gives a magnificent blood-red solution with water, and deliquesces when
exposed to the air. At first I entertained the hope that this substance, though
coloured, might, when submitted to analysis, give the results of ethylopicoline, a
very few experiments, however, sufficed to show that it had undergone decompo-
sition, and no attempt was made to analyse it, but attention was directed to ob-
taining such double salts as might serve to confirm the constitution of the base.
Platinochloride of Ethylopicoline.—In order to obtain this salt, nitrate of silver
was added to the iodide as long as a precipitate was formed, which was sepa-
rated by filtration, and the excess of silver thrown down by hydrochloric acid.
The filtrate was then mixed with a strong solution of bichloride of platinum, and
set aside. In the course of a few hours the salt was deposited in orange-red
tabular crystals, of remarkable beauty, and often of considerable size. It is readily
soluble in cold water, and still more so in hot, and is deposited unchanged from
its solution. It possesses considerable stability, but by long-continued boiling, it
undergoes decomposition. Its analysis gave,—

6-015 grains of platinochloride of ethylopicoline gave
6430 ... carbonic acid, and
2040"... > Water.

6-825 grains of platinochloride of ethylopicoline gave:
2031 ... platinum.

6-910 grains of platinochloride of ethylopicoline gave
2-058 ... platinum.

6-970 grains of platinochloride of ethylopicoline gave
2085 ... platinum.

226 DR T. ANDERSON ON THE PRODUCTS OF THE

Experiment. Calculation.
—=————— 6. ee SS a,
i II. Ill

Carbon, . ; : 29°15 oer: A Pe 29°33 Cre 96

Hydrogen, : ‘ 3°76 So ak 3°66 3 12

Nitrogen, . 5 ore mei tt 4°31 N’ 14
Chlorine, ; : ri sae a 32°54 Cl, 106-5
Platinum, : : 29°75 29-78 29°91 30°16 Pt 98°7
100-00 327°2

Aurochloride of Ethylopicoline—This compound is readily formed, by adding a
solution of chloride of gold to the nitrate, with excess of hydrochloric acid, ob-
tained from the iodide, in the manner employed for the production of the plati-
num salt. It is slowly deposited in the form of golden-yellow fiattened prisms
of great beauty. It is sparingly soluble in cold water, readily in hot, and is de-
posited unchanged on cooling. It is insoluble in alcohol and ether. Ammonia
converts it into a cinnamon-brown powder, and it is instantly blackened on the
addition of potash to its hot solution. The specimen analysed, was dried at 212’,
and burnt with chromate of lead.

6-745 grains of aurochloride of ethylopicoline gave

5093 +» carbonic acid, and

1675 + —_-water.

5-300 grains of aurochloride of ethylopicoline gave

2260"... gold.

Experiment. Calculation.
ae
Carbon, . : ' : 20°59 20°83 Cig 96
Hydrogen, : ; : 2°75 2:60 i. 12
Nitrogen, : : : von 3°06 N 14
Chlorine, ‘ : : tee 30°82 Cl, 142
Golds faeces Aan ea ee 42:69 Au 1966
100-00 460°6

Corresponding with the formula C,, H,, N Cl + Au Cl..

It has been already mentioned that aes eifiylepicolines is fixed and inodor-
ous, its iodide cannot be distilled with potash, or the base itself boiled or even
evaporated in vacuo, without undergoing a decomposition, attended with the evo-
lution of volatile base. In the latter case the decomposition is slow, and even after
the ebullition has been continued for some hours the odour is given off with undi-
minished intensity, till by long-continued boiling it at length becomes extremely
faint although it does not altogether disappear. When the iodide is boiled with pot-
ash, the change is more rapid, and after three or four hours’ boiling a considerable
quantity of base is found in the receiver. The product has a pungent and putrid
odour, fumes strongly with hydrochloric acid, and forms with it a salt entirely

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 227

soluble in absolute alcohol. Two analyses were made of the platinum compound
of this base, the one from a portion collected at the commencement, the other to-
wards the end of the distillation, which show that the product was of uniform
composition throughout. The results were as follows :—

6-440 grains of platinochloride gave ’
I.4 2:430 «- carbonic acid, and
1:920° ++ water.
11-775 grains of platinochloride gave
4:210 ... carbonic acid, and
3457 ... water.
L 4-385 grains of platinochloride gave
1-705 °... platmum.
ie 6°580 grains of platinochloride gave
2575 ... platinum.
Tixperiment. Calculation.
fee Ee, aR Oo
Te I.
Carbon, F : ; 10°29 9°75 9°55 OF 24
Hydrogen, . : ” 331 3°26 2°78 H, 8
Nitrogen, . : : ad as, 5°99 N 14
F Chlorine, i : : se ee 42°39 Cl, 106°5
Platinum, f : A 38°88 39:23 39°29 Pt 98-7
100-00 251-2

Its formula, therefore, is C, H, N HCl Pt Ch, and the base itself is ethylamine.

The base obtained by the distillation of the ethylopicoline alone was found to
have the same composition, for 6°177 grains of its platinum salt gave 2:413 grains
of platinum, equal to 39°06 per cent. ;,

The decomposition which thus occurs is very remarkable, and differs entirely
from that observed by Horrman in the ammonium bases examined by him. The
oxide of tetrethylammonium, for instance, is not decomposed when evaporated
in vacuo. Even at 212° it undergoes no change until it becomes nearly dry, but
then a base and a permanent gas are evolved, the former being triethylamine,
and the latter olefiant gas. In this case, one out of the four ethyl atoms which
the complex base contained is decomposed, and the other three remain with the
ammonia in the form of a nitryl base; in fact we may fairly assume that the
atom of ethyl added to the triethylamine to convert it into tetrethylammonium
is decomposed, and the base which formed the starting-point of that action is
regenerated. With methethylopicoline the case is different; we start, indeed,
from a nitryl base, but in place of reproducing it in the decomposition, the atom
of ethyl which has been added takes possession of the ammonia, and produces an
amide base, leaving the radicals, which we must assume to have replaced the
three atoms of hydrogen in the ammonia from which the picoline was originally
produced, in some other form of combination. In another point, also, the decom-

VOL. XXI. PART I. 3P

228 DR T. ANDERSON ON THE PRODUCTS OF THE

position of ethylopicoline differs from that of tetrethylammonium. According to
Horrman, the latter base is entirely converted into triethylamine and olefiant gas;
but ethylopicoline, even after long-continued boiling, gives an abundant residue
on evaporation. The substance so obtained is amorphous, has an intense blood-red
colour, and is a base forming a platinum salt insoluble in water. Although these
experiments were made on a very small scale, and the slowness of the action
rendered it impossible to say with certainty whether the decomposition was com-
plete, this platinum compound was analysed, and the results were—

8-550 sae carbonic acid, and

5'840 grains of the platinum salt gave
2°390 ... water.

i ‘555 grains of the platinum salt gave

1652 ~..._~— platinum.

Carbon, . : : , 39-92
Hydrogen, 2 : 4°54
Platinum, ; : : 21-86

From a single analysis such as this, it is impossible to deduce a formula; but
it is obvious that a base, of much higher atomic weight than ethylopicoline has
been produced, the farther examination of which must be deferred to a future
paper, and which will probably lead to interesting results.

Action of Iodide of Ethyl on Pyridine.

When pyridine is treated with iodide of ethyl, the action, as might be ex-
pected, is in all respects similar to that which occurs with picoline. A homo-
geneous mixture is first formed, and then, on gently warming, the action takes
place, with the evolution of much heat, and the hydriodate of ethylopyridine
rises to the surface as an oily layer. The crystallization of this substance, as it
cools, is an extremely beautiful phenomenon. Minute rhombs make their ap-
pearance here and there in the viscid fluid, where they increase in size so rapidly
that they may actually be seen to grow; and in a successful operation they
sometimes increase to the size of from a quarter to three-eighths of an inch in
diameter in the course of half an hour. By and by the crystals come into contact
with one another, and the fluid is converted into a solid crystalline mass. The
crystals are removed from the tube, pressed in folds of filtering paper, and crys-
tallized from a mixture of absolute alcohol and ether. They then form fine sil-
very plates, highly soluble in water, and slightly deliquescent; in alcohol and
ether they are also extremely soluble, though less so than in water. With re-
agents, their behaviour is so exactly the same as that of the ethylopicoline salts,
that it is unnecessary to enter into any details. By analysis the following results
were obtained :—

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 229

8:105 carbonic acid, and
2°525 water.

{ 5:445 grains of hydriodate of ethylopyridine gave

6:110 grains of hydriodate of ethylopyridine gave

5395 iodide of silver.

Experiment. Calculation.
Carbon, 36:17 35°89 Ci, 84
Hydrogen, . 4°59 4:27 Ls 10
Nitrogen, 5°70 6:04 N 14
Todine, 53°54 53°80 il 126
100-00 100-00 234

The formula of the substance therefore is C,, H,, N I.

Ethylopyridine itself may be separated from the salt by the action of oxide
of silver. It forms a highly alkaline fluid, which undergoes decomposition when
heated, with the evolution of a base which is no doubt ethylamine, and agrees com-
pletely with it in properties, though the small scale on which the experiment was
performed prevented my establishing this fact by analysis. It unites with acids,
and forms salts, which are all crystallizable, and generally highly soluble. The
platinum and gold salts are extremely beautiful compounds.

Platinochloride of Ethylopyridine.—This salt was prepared in the same man-
ner as the corresponding ethylopicoline compound. It is sparingly soluble in
cold water, and insoluble in a mixture of alcohol and ether. When slowly formed,
it is obtained in beautiful garnet-coloured rhomboidal plates with bevelled edges,
which are easily got of a quarter of an inch in diameter, even when operating on
very small quantities. Its analysis gave—

6°905 carbonic acid, and
1°885 water.

( 6-435 grains of ethylopyridine platinum salt gave
\ 2°035 platinum.

7:152 grains of ethylopyridine platinum salt gave

Experiment. Calculation.

Carbon, 26°33 26°81 Cua 84
Hydrogen, 2°92 3°19 Tait 10
Nitrogen, i 5°56 N 14
Chlorine, aps 33°93 Cl, 1065
Platinum, 31-62 31°51 Pt “987
100-00 313-2

The formula of the compound is C,, H,, N Cl+PtCl..

The gold compound of ethylopyridine is obtained in fine yellow plates of ex-
| treme beauty, sparingly soluble in cold water, and readily decomposed in boiling,
especially if an excess of chloride of gold be present. They were not analysed.

230 DR T. ANDERSON ON THE PRODUCTS OF THE

Action of Iodide of Ethyl on Collidine.

Todide of ethyl and collidine react upon one another in the same manner as
the bases already mentioned. An oily layer separates on heating the mixture,
which refuses to crystallize on cooling. After removal from the tube in which
the action was effected, and separation from the excess of iodide of ethyl, the
fluid was allowed to stand for some time, but no crystals appeared. It was then
exposed to cold, in the hope of inducing crystallization, but without success; and
no better result followed the attempts made by dissolving in the smallest possible
quantity of absolute alcohol, and adding ether. As the properties of the com-
pound did not appear promising, no further experiments were made with it; but
it was converted into a platinum salt, for the purpose of ascertaining whether
the collidine had actually combined with ethyl. The process employed was the
same as that used for preparing the ethylopicoline salt. A sparingly soluble and
scarcely crystalline compound was obtained, the platinum of which was deter-
mined by the following experiment :—

5°855 grains of the platinum salt gave

1°618 platinum.
Experiment. Calculation.
Carbon, 34:06 Gj, too
Hydrogen, . 4-50 is Oe 16
Nitrogen, 3°68 N 14
Chlorine, x 29:98 Cl 106°5
Platinum, 27°65 27°78 Bt 98-7

100-00 350°2
This corresponds completely with the platinum salt of ethylocollidine, but as
that substance did not appear likely to give results of interest, I contented myself

with this experiment as a sufficient proof of its existence.

The experiments described in the preceding pages sufficiently establish the
fact that picoline and its homologues must be considered as nitryl bases, that is
to say, bases capable of taking up only one additional atom of ethyl or any simi-
lar radical, by doing which they are converted into fixed compounds, of the class
designated ammonium bases. If this be their constitution, we must, according
to the views at present entertained, assume that these bases are formed from
ammonia by the replacement of its three atoms of hydrogen by as many different
radicals. Of the exact nature of these radicals, the experiments we at present
possess afford no data for drawing definite conclusions; but a moment’s consider-
ation suffices to show that they must be substances remarkable for the simplicity —
of their constitution. If we confine our attention to pyridine, as the fundamental

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 231

member of the series, it is obvious that the ten equivalents of carbon and five of
hydrogen which it contains must be distributed among these three substances ;
and although we cannot, without further researches, determine how they are
distributed, it is at least sufficiently obvious that the choice among different spe-
culative arrangements is by no means large. In fact, our knowledge of the
laws governing the constitution of organic compounds, enables us to see that the
total number of possible permutations} of the elements of pyridine is only eight.
They are as follows :—

*
C, H,) C, H,) C,H C,H)
C, H.-N C,H /N C, H »N G, H,-N.
oe a cus CH, C, H,

* *
C, H, C, H,) C, H C, H
ee oe C, H }N C, H,>N

C, H C, H, C, H,

Involving the abt of the following nine radicals, all, with the exception of
methyl, at present unknown :—

C, H, C, Hi, C, Hi,
C, H, C, H, C, H,
C, H C,H C, H

Of these, two at least, C, H and C, H, are so extremely improbable, that we
may, without much hesitation, pronounce against them; and if so, the probable
formulee of pyridine are reduced to those marked with an asterisk. The question
for consideration is, whether even these can be supposed to represent the constitu-
tion of the base in a feasible manner. On this point no experimental evidence can
at present be adduced; but taking into account all the circumstances connected
| ‘with them, my impression is, that none of them give the rational expression of its
| constitution, and that pyridine and its homologues belong to a class of bases of
which we have as yet no other examples.

In illustration of this opinion, it is necessary to enter into some details re-
_ garding the constitution of the bases generally. Itis scarcely necessary to remind
| the reader that when Horrman described his two new series of volatile alkaloids,
_ he applied to those already known the name of amide, and to the new series
| those of imide and nitryl bases. This nomenclature, which has been more than
| once employed in the preceding pages, was founded on the analogy in constitu-
| tion of those substances with the well-known amides, imides, and nitryls. A
| very little consideration, however, suffices to show that this analogy is by no
| means complete. The first series of bases may be correctly compared to the
| amides, but the other two have no close resemblance to the imides and nitryls.
| On the contrary, they are strictly comparable with the secondary and tertiary

+ I assume, with Geruarpr, that the number of atoms of carbon in any radical must always be
| diyisible by two.

VOL. XXI. PART I. 3 Q

232 DR T. ANDERSON ON THE PRODUCTS OF THE

amides recently described by GerHARDT and Cu1ozzA, which are formed from the
primary amides by a process similar to that employed by Horrman to produce his
two classes of bases. The closeness of this analogy may be seen from the sub-
joined comparison of these methyl bases with the benzoyl amides.

Methylamine. Bimethylamine. Trimethylamine.
(5a, C, H, C, Hs)
H }N C, H,-N C, H,,;N
H H owl
Cy, H, 0, Ci, H 0, C,, H, eat
H oN C,, H,; OL AN Cy, By OLAS.
H H C,H, 0,)
Primary Benzamide. Secondary Benzamide. Tertiary Benzamide,

From which we see that in every case hydrogen is replaced, atom for atom, by a
compound radical, the only difference being, that in the one set of substances the
ammonia retains, in the other it loses, its basic properties.

But the constitution of an imide or a nitryl is materially different. Of the
former, indeed, we know too little to admit of any satisfactory conclusions regard-
ing their constitution; but taking benzonitryl with the formula C,, H, N, as an
example of its class, and examining its constitution in the same point of view,
we may consider it as an ammonia, in which three atoms of hydrogen have been
replaced by a single radical C,, H,. While, therefore, an amide is formed by the
replacement of one or more atoms of hydrogen in ammonia by an equal number
of molecules of a monobasic radical, a nitryl may be viewed as an ammonia with
its three atoms of hydrogen replaced by one atom of a tribasic radical; and in the
same manner there must exist a class of compounds, which for the present we
may call imides, although they are not comparable with the substances known
under that name, in which part of the hydrogen is replaced by a bibasic radical.
The different forms of combination possible under this view may be best rendered
intelligible if we make use of general formule, and take X’, X”, and X” as re-
presenting respectively a monobasic, a bibasic, and a tribasic radical. We have
then the following expressions for the different classes :—

(1.) (2.) (3.) (4.) (5.) (6.)

Hl x} xy i }x x } % wee

H H x)
Of these the first three represent either the amides, or the bases described by
Wurtz and Horrman; the last is a nitryl, and the others are substances at present
scarcely known.

Now as regards the first three classes, it is manifest that they prove amides or
bases, according to the properties of the radicals replacing the hydrogen; and we
may fairly argue from analogy that the members of the last may be also either
basic or non-basic. The nitryls at present known are all non-basic, but it is my
belief that the most probable explanation of the constitution of the bases of the

ee

DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 233

pyridine series is to suppose that they are true basic nitryls, and that, for instance,
in pyridine itself, the tribasic radical C,, H, replaces three atoms of hydrogen in
ammonia. The opinion thus expressed regarding the constitution of these bases,
and even the possibility of such compounds existing, is speculative, but at the same
time it is not altogether unsupported by facts, for though we have no bases in
which a tribasic radical exists, there certainly are instances in which two atoms
of hydrogen are replaced by a bibasic radical. A marked example is found in
GERHARDT’Ss platinamine, although there the replacing substance is not a com-
pound but a simple radical. Its formula may be written thus :—

ae

in which platinum is a bibasic radical replacing two equivalents of hydrogen.
Diplatinamine may in the same manner be represented, with its formula written

thus :—
jer
H, } N,

in which two equivalents of ammonia have been brought into play. Lastly, in
furfurine we have a purely organic base, formed from two equivalents of ammo-
nia by replacement of the whole of its hydrogen by three atoms of a compound
radical, its formula being—

Cio H, 0,

Cio H, oN,

Cio H, 0,

The view now expressed would make the constitution of the bases correspond
very closely with that of the acids, as explained by Grruarpr. According to
that chemist, a monobasic acid is formed from one atom of water (viewed as
H, O) by replacement of hydrogen by a monobasic radical, while a bibasic acid is
formed from two atoms of water, by the replacement of two atoms of hydrogen
by a bibasic radical.

I have been led into these observations by a desire to explain in a more satis-
factory manner than our present knowledge of the bases will permit, the constitu-
tion of pyridine and its homologues; but I am now about to enter upon a series
of experiments, with a view of obtaining some of the bases

= . xe XIN

H x" |
the probable existence of which I have new indicated on theoretical grounds,
which may probably form the subject of a future communication.

I may further mention, that I have found that the platinum salts of pyridine
and picoline undergo a peculiar decomposition when boiled, platinum bases of
very remarkable constitution being formed. I am extending this investigation to
the other bases, and hope that my experiments will, at no distant date, be suffi-
ciently advanced for publication.

N

< i uv eh Oy 1 ¢ Y writ e"
, "Ys i
ERS LATERM TA MVER BO ORDATIUTW NE

wiiintads not Aeuk? fvern ebrsteni Ghaachomnd sant y jultt nba
_eAbamagstlog! Yo 2s vte-oaeds ohunlgos AH ipl) toot aiden la Mai req tt
ahead lo noitititiiing othr yrbbeenieng hosaanpzrr eddy, : ces

z seemed ta dari NRO RIE i. «.-<sanerpiemwere shousto ifidineng pre bi

ni ancim! 0 roll ore ipaods aiteastoah ad Testiogtratio-silignatter ip :

amos owt idoid@ st oka hei si zitiatien ai) 2tei xo Inoihaa ai a r abe
‘4 Dewob cad Aq maRrg- Dyalnern A. Leather ainanlid ad haidlast drep
- “o> & iit et bape Birk aed Oe offf woud Apwodisn ASA beac, Tah
oy eat dad ett “0 eal van hiylipad et. becitbcr Mepertig a

ehre Fi “=

Ae eee

Lhomereatieder enoTa vite, OFA) welt inter test imee” falar ee a pee
nt isles “nat Hit ceniad ni tonettiets Stele oP aT Yee
pry matin fi

7 BR ( Tf a [oha binky af o

h ‘ 7 Se ifieine coment

fi Vian <r galey won siterasas non vest Binet To navies g
One lo ahrolintnpe dented iors ial St etio y Meing 8 oy
boeest MOD KE career yd denginl bei ari kweatonber wil to dies

; as phat, iy heh Sasa areal ie Sheil

ae ud th

ae: , : palsy to > ae

:: 4 . . , ‘ ee 4 ‘ A : ‘ . ;

y ati q . a 1e aa j = at :

- ’ A 7 ory rs We hom og way bs ‘
, hnagmagi) ~~ ie erg ni} to Poltitaenes: “ey “ Age hl ite) Ww be : Wore 9

a I yiiind1i/, Tisawaxs! vd fh

HOTS 60 bhatt to Snake diieee “I

i THY) a i mors fa pe heatwrtsl 2 hion vigadonpys as
| cae, fa a ie Mister .froiben gieedn mig ed seraestvl In Shope
ay. va eRe on) HY OOS WE ae toy tainly ont,

—" ks . leoihint Gai
IBS ST ae ning a HQONLETS logen'? ofni ee oe OF,
he & Horta OF todiin Hoi’ wad Bak os ab oo foters as eli oa nike vi aah
; “9 evand white ine palinide Yo WAR itive ners
. ome
a wy ; es ott
ory Les erie Oba ine wale at ToD Yo an talss Sidiadl
OT ANMOD oe Ato doaidud ott tom vided rig van
‘\ To’ atLow open nhp nie Gat Hervit D tie other stint vant
p64 , LeNy Letiod weir tolimentiiingt shy aise ati Snilos
Pe TZ) pin Bae By Det we ha roitiudtiency ' ‘olde dukes
shiv :

2 EE CHTSUIMI LS VCP TERY Oy Ort hick Sed te
, Ho PaMi let iy tk i howrnayig

ie | : . bali ey eS rae a er Sr eee

( 985 )

XIV.—Further Experiments and Remarks on the Measurement of Heights by the
Boiling Point of Water. By James D. Fores, D.C.L., F.R.S., Sec. R.S. Ed., &c.,
Professor of Natural Philosophy in the University of Edinburgh. (With a
Plate.)

(Read 4th December 1854.)

_In 1843 I presented a paper to the Royal Society of Edinburgh, giving an
account of experiments made on the boiling point of water in the Alps, un-
der various barometric pressures. My object was twofold: first, to describe an
apparatus which I considered more practically available than those previously in
use; and, secondly, to give a simple, and, as I believed, new formula for comput-
ing heights from such observations.

With reference to the second point, I became aware, some time after the pub-
lication of my paper, that Sir Joun Lestiz had proposed to compute heights by
the thermometer, assuming the change of the boiling point to be exactly in pro-
portion to the height ascended. While cheerfully conceding to Sir Joun LESLIE
priority on this point, 1 submit that he did not bring forward experiments to
justify its practical adoption.

Of late years both the instrument and the formula have been objected to by
M. Reenautt of Paris, and the latter by Dr JosrpH Hooxsr, who finds that it
does not correctly represent his Indian observations. This has caused me to
examine the whole subject, and also Dr Hooxksr’s observations on the boiling
point, with the particulars of which he has kindly furnished me, and I proceed
to lay the details before the Society.

In 1843, when I wrote, the method of determining heights by boiling water
had fallen very much into abeyance, principally owing, as I believed, to the
inconvenient instruments employed, and partly to the uncertainty of the deduc-
tion of heights. As the thermometric method is principally valuable when baro-
meters cannot be safely transported, and must always be inferior in accuracy to
good barometric results, my intention was to do a service to physical geography,
by introducing a convenient and effective instrument, by means of which water
could be certainly made to boil even in untoward circumstances, and the tempe-
rature ascertained, not to the illusory nicety of two or three decimals of Fau-

‘RENHEIT’S degree, as Archdeacon Wo Ltaston attempted, but to within about
goth of a degree, corresponding to about 25 feet of elevation, which I stated as
the utmost degree of accuracy which I expected to attain, even in favourable

VOL. XXI. PART II. , ; 3R

236 PROFESSOR J. D. FORBES ON THE MEASUREMENT OF HEIGHTS

circumstances.* The formula of one degree of lowering of the boiling point for
550 feet of elevation, in an atmosphere at 32’, I stated to represent my observa-
tions quite sufficiently, and better than Datron’s Table of the Elasticity of Va-
pour, which was the one then commonly in use. I refer to my former paper
for a description of the boiling apparatus, consisting of a thin copper pan heated
by a “ Russian furnace,” having a powerful jet of inflamed alcoholic vapour. The
thermometer (contrary, I believe, to the usual practice) had its bulb in the water,
not in the steam.

In 1844 M. Reenavtt published in the Annales de Chimie a table of the elas-
ticities of vapour at moderate temperatures, and a comparison with some boiling
water experiments in Switzerland and the Pyrenees. He also contrived (I am
not sure at what date) a small apparatus for the use of travellers, somewhat
resembling Archdeacon WoLLASTON’s.

In 1845 he published a second paper on the same subject in the same Journal,
in which he quotes my observations, which he rejects as not conforming to his
law of Elasticities of Steam, and attributes their discrepancy to faults in the boil-
ing apparatus, and to errors of graduation of the thermometer.

The slightest comparison of M. Reanavtt’s paper with mine, shows, how-
ever, that the discrepancies complained of do not argue anything against the ac-
curacy either of his Table of Elasticities, or of my mode of observing; but they
disappear almost entirely when the correction for the index error of the thermo-
meter I used is applied to the temperatures observed. ‘This index error (0°62 in
excess) is given in my paper (page 414), and, of course, should have been applied
when it was intended to compare absolute temperatures with absolute pressures,
but had not been used by me when my object was merely to ascertain the 7rela-
tive variation of those quantities, as in page 412. When the index correction is
applied, the deviations of my observations from M. Reenavutt’s Table fall, as will
be immediately seen, considerably within those of M. Marm quoted by him, of
which he says that they “s’accordent avec la formule aussi bien qu’on peut le
désirer.’’+

To the observations of 1842, made in the Alps, and published in my former
paper, I have now added a fresh series, made in 1846, with the same apparatus
and thermometer, which confirms them in a remarkable manner. These series
are denoted by I. and IJ. in the following Table. They were projected in the
manner described in my former paper, the ordinates being the temperatures, the
abscissee the logarithms of the corresponding observed barometric pressures, which
numbers are proportional to the heights in an atmosphere of uniform tempera-
ture. Through the points a straight line may be drawn, with a very close approxi-
mation (See Plate III., fig. 1). The deviations of the observations from this

* Transactions of the Royal Society of Edinburgh, vol. xv., p. 411.
+t Annales de Chimie, 3me Serie, vol. xi., p. 332.

RAGS. 199°

200°

201°

202°

203°

Ed. Royall Society Trans. Vol. XXT. p. 236.

204° 205" 206° Zoe. 2085 209° 210° 2 212° 215°
| Bowling point | | bon fe
| | i | | | e
S| ee . sie LIS Gb . pote Siders { = | = “id :
| ; | | | |
“ | | | | | | | | |
‘VERMINATION or HEIGHTS | | al
+ ——}— _ — —j—— ——_+——- —— — — _ _- - a eee —
- BY THE | | |
| |
BOILING POINT. |
St a5 1 ea oe aaa ga cece Tete, = ale
x |
eae ~~
| Beare Stix lel es hanes,
| he ae
SSE SEL 2 Ds ce ets on ae €.
oT g emenend |
OR FORBE S'S EXPERIMENTS IN THE PS &e. | |
— ino es "ic [ ir = = — a r ss Tie poe = —- = Bil
)
|
PM ae se ante te 2 pain EE Psa ro ce ees
| AG !
| | 4
ean Pi agers - dP
+- a 4 ers 128 sn EDI DN Ves Ne ' ~ 48
. HS ha ee |
| ee Bes er ary aol
+ | ve Haat | can (et Pas oy H
eat ; ay += aia = Shad Bee ee ae —-#6
| | | | | | ; | | ae |
L | 1 ae at aera
ee =I cai Wail [-SSesyeee =" _ ee
[==
eee a | | [ a J | | . |
( ; Se | {
=p ie i ps ; —-— he eas Seo
eee rs
eee | | orl aS Na
| | | Gerace i | } eae
- a eee ee ee
i | | | v | | | i yt os
fe ee arm's 4 b =e 1 — :
| ea | i re | aA [7 | | . S
Sa Mee sat ghee Seo I eI Iara Pak
eee ee nee ee! ae eee eee
; | H | | | | | | Pensa
|} tH Nr eat (ooo SI56
| | | } | } | | x.
} H } | i t / 1 i d vs SS
Beret te . ens
nese ee hse
| | | | { n = = 4. |
Saal = | 4 Z pp tee 32
| 1 i
eee) 2 a fe ea ae a +
i le se Tig. 2. | | jee a es
4 Ly = | T T <
aoa DAHOOKEIS EXPE NTS IN THE HIMALAYA.
+ L ie i . —
jar | ; (Half scale |
cael er eee ae
| | | | H
a ieee i rant ae eae = fy |
| | rat | | IE | | ees ee ha eel 26
; j 4 A. ia as —— ; + | | “= = T } .
[ «| HE | ; ; |
| a aa ae trots) Boiling point eee
2 SS a Re 8° | 200° 2o2°_| 294° | 206" | 206° | 20" | 212°
wee ae i Bim 24
Sian = — 4 - = SSS oo SH
| | | | | 7
ae A Nae oS | 22! g
ih PIGS.
a es
T
——! oe cli eee - A
|
velo. mais ee
> = ite . ! ee 148]
ug potmt | | | P
186° 188° 190° 192° 194° 196° Jno. Johnstone St.

BY THE BOILING POINT OF WATER. 237

simple law are given in the 6th column of the following Table. Column (7) gives
the temperature from M. Reanavtt’s Table in the Annales de Chimie.

Barometer corrected Temp.
SERIES. | and reduced to 32°. | Boiling | Linear
Water | Formula.

REG-
Difference.| NAULT’S |Difference. LocaLiIrTy.

Millim. |Eng. Inch|Observed* Formula.

Col Collon.
Aiguille du Moine.
Breven.
St Bernard.
Tacul.

Do.
Prarayon
Montanvert.

Do.

Do.
Naversch (Gressonay.)j
Chamouni.
Martigny.

(7.) | @.) (9.)

* Corrected for Index Error+ 0°65.
} Evidently a mistake; the error amounting to nearly 1}°.

The following comparisons with the same apparatus and a different barometer,
I find recorded as made at Edinburgh in January 1843.

Barom. Boiling Point
corrected. corrected.
27-760 208°57
29-040 DOs?)
29°879 211:95
30°064 212-18

If we project the Alpine observations alone (which are the most consistent
with one another), in the manner exemplified in my former paper, as is done in
Plate III, fig. 1, I find that they may be admirably represented by a straight in-
terpolating line (giving the results recorded in column (5) of the preceding Table),
and yield the following results.

The wncorrected reading of the thermometer, at the standard pressure of
30 inches, is 212°:75; at a pressure of 760 millimetres (29:922 inches), 212°°62,
The Edinburgh observations (distinguished by the letter ¢), taken separately,
give almost the same results.

The Alpine observations above give a uniform rate of ascent of 543°2 feet for
1 of fall in the boiling point. This is when we use Lapiace’s barometric coeffi-

238 PROFESSOR J. D. FORBES ON THE MEASUREMENT OF HEIGHTS

cient for a standard atmosphere at 32°. It is about 6 feet less for 1° than I formerly
deduced. If we include the whole of the observations (Edinburgh and the Alps),
the rate of ascent will not be sensibly altered, though the squares of the errors
will be somewhat increased.

The coincidence of the formula with observation, shewn in column 6, is highly
satisfactory. In only three instances does it exceed a tenth of a degree of Fau-
RENHEIT.

The coincidence with M. Reenautt’s Table, shown in column 8, is not less
satisfactory (a very slight change in the index error* would neutralize the pre-
ponderance of positive errors).

From the mode of experimentally obtaining his results, M. Reanauut’s Table
is in fact a table of boiling points (see Ann. de Chimie, 1844), which was not the
case with Datron’s Table, which differs from it sensibly: and I have no doubt
that M. REGNAULT’Ss are, on the whole, the most accurate numbers we at present
possess.t

Hence,

1. Observations of height by the thermometer down to about 190°, or for
elevations not exceeding 12,000 feet, may, within the usual limits of error, be
reduced indifferently by M. Reanavuut’s Table, or by my arithmetical proportion.

2. The method of placing the thermometer in water instead of steam, and of
using a powerful alcoholic furnace, which may be removed to one side until the
escape of steam becomes uniform and moderate, { appears to give remarkably
steady and consistent results. The graduation of the thermometer, as regards
the length of the degree (which was entrusted to Mr Apis, and on which M.
REGNAULT throws doubts), is sensibly correct.

3. 543°2 feet per degree seems to express the observations better than 549°5,
formerly given.

Let us now turn to Dr Hooxer’s observations. In his “ Himalayan Journals,”
vol. ii., p. 456, speaking of his numerous observations on the boiling point at a

* The reason for this change in the index error, according to the two hypotheses, will be seen in
the concluding paragraph of this paper.

+ I still retain the doubt expressed in my former paper, as to whether the boiling point can be
taken correctly to represent the temperature of steam whose elasticity is that of the atmospheric
pressure at the time. This doubt is confirmed by the difference of M. Reenavutt’s and Maenvs’s
Tables of Elasticity, as also by experiments of a different kind. I take this opportunity of adding,
that I have obtained true ebullition of water in an exhausted receiver at the low temperature of 46°;
the syphon-gauge then stood at 0:25 inch, being -06 below the elasticity of vapour, at that temper-
ature, as given by M. Reenavtr.

+ The superabundance of heating power, and the mass of liquid in ebullition, I consider very
important to the good result. No other portable apparatus that I am aware of, gives so ready means
uf adapting the force of the flame to the circumstances of the case. With a common spirit-lamp in
fixed position below a boiler, it is next to impossible to regulate the rate of boiling, especially in an
exposed situation. Mine is also the only instrument, so far as I know, which can be used in a gale
of wind.

BY THE BOILING POINT OF WATER. 239

ereat range of elevation, he states, that having deduced the heights by my for-
mula, he finds that it ‘‘ is certainly not applicable to the Sikkim Himalaya,” but
that Captain Borzau’s Tables, founded on M. Reanautt’s, give, at all ordinary
elevations, a “very close approach to accuracy, on the mean of many observa-
tions.” We find, however, from the results which Dr Hooker has himself given
at page 458, the average difference of the barometric and thermometric results is
far from showing a close agreement, and seems to throw a doubt on the suffi-
ciency of the observations for testing one formula rather than another.

The average error (without respect to sign) of each observation is about 140
feet, or 0°-26 of a degree, whilst it occasionally rises to half a degree, or even a
whole degree; and this by the formula preferred by Dr Hooker. The average
deviation of my observations from the formula is only 0°08.

Desiring to arrive at the exact truth, and to test the alleged inapplicability
of a linear formula to the-Indian observations, I wrote to Dr Hooxer, requesting
him to send me as large a selection as possible of direct comparisons between the
barometer and the boiling point at different heights. With this request he most
kindly complied, sending me (with much trouble to himself) a long series of com-
parisons, which he had drawn from his original note-books. From the extent
and range of these, I consider them well worthy of preservation, and accordingly
transcribe them in the following Table.

Sikkim, Himalaya, Boiling Points.

seamen SLY A ti
Great Rungeet River, . 210°8 Se 29-211
Bhomsorg,: , PAE ale a 28°559
Gt. Rungeet Oaerd: foe 208:4 207°8 Te Ws
Do., : 208-4 207°7 27°781
Choongtam, . . : 202°5 202-6 24-697
Dengha, : 20026) aan 23°726
Mr Mutuer’s (Dorjiling), Ser 199-0 23°372
Wor. 199-6 -- 199-5 23358
Dr Campzett’s (Dorjiling , 200-1 200-1 23°369
Mr Hooeson’s Cee zy 199°5 199°3 23°030
Sinchul, ; LS OM s.. 21:892
Lachoong Village, : WO Ge4e 87; 21°928
iDYes + . 4 H9Gr4" 3. 21°751
Lamteng, . ; ‘ HIGra a2. 21654
Zemu Samdong, . : 195:9- 196-1 21-605
0... : : F 196°3 196-2 21°596
Do., . j ; 196°3. 196-1 21:633
Mainom, 193-4 ane 20:480
Junction of Zemu & Thlonok, 192-6} 192-6 20°212
Tallum Samdong, : 1914 191-6 19-758
Do, . : : UOQ les 19229 19°881
Yeumtong, . ‘ ‘ One USileD 19:490
Do. i : ‘ OTE Bi yo. vege 19°505

* S means small and L large Thermometer.
{ 193-6 in my “ Journals,” by error apparently ; for I find 192°6 in my Note-
book and Calculation-book.—J. D. H

VOL. XXI. PART II. 35

240 PROFESSOR J. D. FORBES ON THE MEASUREMENT OF HEIGHTS

Sikkim Himalaya, Boiling Points—(continued.)

STATION. tae yes Barom.

Corrected.

Zemu River, ; ; 190-6 190-2 19:386
Tungu, : - ; LB DD: vii 18:869
Do., : : , BOB” 18-974
Do., é a j 190s" 18-952
Jongri, ; : : [SBE test 18-356
Zemu River, ‘ : Ieyeia, | pee 18°507
Lachee-pia, . 4 : 185-7 17:267
Dos; Tih : ; 186-1 17:317
Momay Samdong, . UsRq0) oe L220
‘ 185:9 17°215
186:5 17:230
185°6 17:062
: ‘ : : 185:3 17:091
Kongra Lama, : ° Loa! VEE 16-959
Snow-bed above Yeumtong, 184-B.00 | ke 16:881
Tunkra Pass, : : 184-1* 16°817
Yeumtso, . : : 183-2 16°385
Donkia, ; : ; oa BAe aa 16-235
Mt. above Momay, : et aa 16°106
Sebolah Pass, 4 s i HRS eee es 15:928
Kinchin-jhow, ‘ : LBL UGS, 15-919
Donkia (W. flank), ; 1G0rG4° oan 15°376
Do. (S. flank), : 179°9 15°442
Bhomtso, : : . a5 15°548
Donkia Pass, : : 181:0 Bae
DO : i 181°6 15:489

* 164:1 by misprint in my Journals.—J. ]). H.

Khasia Mountains Boiling Points.

Boiling Point. Barom.
8. L.

T N.
STATIO Corrected.

Churra, ‘ . : 2043 204-4 25-596
Amwee, : : 20531. 25°981
Nurtiung, . : . 205:0 + 25°913
Nunklow, . : : 2OS:9l aN .. 25-083
Kala Panee, . : é 2021 SE 24-4992
; . 202) ve 24559

202:0 aan 24-556

202°6 ays 24:668

ZOUGH) 38 24:453

2020) \ we 24°386

DOT GP nea es 24-219

2019 y Oe 24.319

201:0 201-1 23°936

QOL aie ees 24:009

‘ : : - DOL eT. eee 24°133
Do., : : : 202-000 te. at
Chillong, . ; : DON Deere 23-727

BY THE BOILING POINT OF WATER. 241

Upon carefully projecting Dr Hooxer’s results in Plate III., fig. 2, in the same
manner as my own, that is, by exhibiting the logarithms of the pressure (or the
heights) in terms of the temperatures of boiling water, I found, in the first place,
large deviations among the results, increasing also at great elevations. The
breadth of the space is so considerable over which the individual observations
are distributed, that it seems impossible, from the observations only, to assign
any one curve as particularly indicated by them; and for the most part they are
as well represented by a straight line as by any curve not absolutely sinuous. I
must, however, note that below the temperature of 187°, or at heights above 13,600
feet, something like a dislocation occurs in the continuity of the observations. Dr
Hooker was aware of this circumstance, and ascribes it to “the metal of the
kettle, and consequently of the thermometer, getting heated above the tempera-
ture of the boiling water.”” Whatever may have been the cause, this part of the
series, the most important for testing a formula, can hardly be relied on for that
purpose.

There is no doubt that M. Reanavutt’s numbers represent, as well as any num-
bers can be expected to do, the main features of Dr Hooker’s observations.* But
the differences between M. ReGNAuLt’s numbers and my approximate formula are
trifling, compared to the latitude of error which the projection of the observations
themselves discloses. Balancing the errors as nearly as possible, the observations
between 212° and 190° are well represented by a line which gives 538 feet of ascent
for a fall of one degree in the boiling point, which it will be seen differs only by
Tooth part from the corrected result of my Alpine observations.;+ I beg to observe,
that this coincidence is the more striking, because, from the method of projection

used, it was zmpossible to guess at the numerical result until the interpolating
line had been fixed upon.

In criticising Dr Hooxer’s results, I do so with every feeling of courtesy and
respect, in the same spirit, in short, in which I am sure he found it necessary to
state his objection to my formula. The whole of his barometrical observations
appear to have been made with the greatest care and fidelity, and, judging by the
results, with great success. From not knowing his thermometric apparatus, I am
unable to determine why these observations are of less value. I should attribute
it rather to the boiler, or to the mode of using it, than to the thermometers; for
Dr Hooker speaks of a coincidence in the readings of different thermometers so
exact as to be unusual. Dr Hooker states that he finds the errors by actual cal-
culation considerably less, if reduced by M. Reanavut’s numbers than by mine;

* A few points marked by the letter r, calculated from Reenavtt’s formula, are inserted in the
figure for the sake of comparison.

+ The entire series of Dr Hooxer’s observations is best represented by 548 feet for 1°, when
we include the (somewhat doubtful) highest observations. This agrees almost exactly with my
earlier determination,

242 PROFESSOR J. D. FORBES ON THE MEASUREMENT OF HEIGHTS

but I imagine that the difference will almost disappear, if he adopt the slightly
altered value of the coefficient given in this paper, from which we have seen that
the coefficient deduced from his observations alone does not sensibly differ.

To complete the subject, I have discussed, in the same manner with Dr
Hooxer’s and my own, the observations made in the Alps and Pyrenees by
MM. Martins and Bravais, by M. Marte, and M. Izarn, which M. Reenavutr
has quoted very justly in confirmation of his formula, which represents them ex-
cellently well. These I find also extremely closely represented as far as 90° Cent.,
or 194° Faur., by a linear formula, of which the coefficient for 1° Fanr. is 531 Eng.
feet; but the greater part are made at comparatively small elevations. The ob-
servation for Mont Blanc alone gives 543°4 feet for 1°.*

These results, it will be seen, give a coefficient somewhat less than Dr
Hooxrr’s or my own. The greater part, however, were made at small eleva-
tion, and, consequently, give a less accurate mean coefficient.

It has been shown, in the previous part of this paper, that the Table of M.
ReEGNAULT (which had not been published when I last wrote) represents my obser-
vations as satisfactorily as the simpler formula which I used, whilst it expresses
probably better the results at very great and at very small elevations. Dr
HookeEr’s observations, though hardly decisive as to the preference of one or
the other formula, are also well represented by M. REGNavuLT’s numbers; whilst
those made under M. REGNAULT’s immediate superintendence, with instruments
expressly constructed and graduated by his direction, coincide, as might be ex-
pected, very nearly with his Table. I claim, therefore, no preference for my for-
mula, except as a convenient approximation to the truth, sufficiently accurate for
heights under 12,000 or 13,000 feet. But I find that the results of M. Reanavtt’s
empirical table may be expressed with an accuracy almost perfect, within the
extreme limits of observation, by a formula so remarkably simple as to dispense
with the use of any tables whatsoever, and which, therefore, may be used in-
stead of the still simpler approximation, and with little more trouble. If we as-
sume the boiling point at the lower station to be 212°, then the elevation in feet
of a station where water boils T degrees of FanrenuEIT lower will be exactly

h olen ere ee ee a re

or in metres and centigrade degrees, 2 = 284T + T?.t

* In the calculation of Dz Saussure’s observation on Mont Blanc, in my former paper (Ed.
Trans., vol. xv., p. 414), a slight mistake occurs. The depression of the boiling point should be
26°-81, instead of 26°71, giving 545-9 feet for 1°, agreeing strikingly with the other results.

+ It happens by a double fortunate coincidence, that the coefficient of T?, is equivalent to unity in
both cases, when the proper reductions are made.

BY THE BOILING POINT OF WATER. 243

This rigorously represents M. Reanautr’s Tabular numbers up to a height of
20,000 feet, and probably much farther.

The distinction between the results of this formula and the one given in this

aper
- | jatess yaa be hs : : : ; : (B)

(where 7 is 540 nearly),* is easily specified, and their practical agreement within
certain limits shown, as follows :—

(A) is an equation to a parabolic arc PQ (Plate IIT., fig. 3), referred to a line
PR parallel to a tangent at the vertex; (B) is an equation to a straight line pq,
not necessarily passing through P (if we assume a small correction Pp for the
standard boiling point), but which shall represent the parabolic arc PQ as nearly
as may be. It may be shown that the greatest deviation of the line pq from
the curve at any point need not exceed one-eighth of the value of T’ in formula
(A). If we suppose the range of the boiling point to be 20°, (corresponding to an
elevation of 11,000 feet), T? is 400 feet, and the greatest error of the linear
formula at any height inferior to 11,000 feet is 50 feet, corresponding to one-tenth
of a degree of FAHRENHEIT, thus confirming the results previously arrived at.

EDINBURGH, 4th December 1854.

* Tf we aim at representing M. Reenavtr’s Table only, between the temperatures 212° and 192”,
the coefficient should be only 535. The difference in the kind of glass used in constructing thermo-
meters would alone account for the variation. The reason of the different coefficient in the formule
(A) and (B), arises from the different inclination of the tangent line PT, and the intersecting line p q,
in Plate III., fig. 8, as explained in the succeeding paragraph of the text.

Loe
Ue|

VOL. XXI. PART II.

1a SDs
Bsr: b veh sale heme: #9)

ipa vi

btae

i ipa |
fee mayer —
” (he ‘Ll
BT lia
PUet Te thie

( 245 )

XV.—Some Miscellaneous Observations on the Salmonide. By Joun Davy, M.D.,
F.R.S. Lond. & Edin., Inspector-General of Army Hospitals.

(Read 18th December 1854.)

The interests connected with the natural family of the Salmonidee, both in rela-
tion to river-sport, the pleasant recreation of angling, and to material wealth, in the
instances of the migratory kinds, are so considerable and fully admitted, that I
trust no apology is required for submitting to the Society any observations in the
least likely to contribute to a more intimate knowledge of the species, whether as
regards their structure or their habits.

1. Of the Air-Bladder of the Salmonide and its contained Air

I have examined this organ and the air contained in it in the salmon, white
trout (S. trutia), charr, and common trout. In each instance I have found it
very similar; of a cylindrical form, tapering at each extremity, composed of a
transparent membrane, very faintly and partially vascular, extending the whole
length of the abdomen, and, with one exception, without colour. The exception
was that of the charr, in which, when the fish were strongly coloured red (their
muscular substance), it, the air-bladder, was often seen of a rose-hue. I have not
been able to detect in any of these fish a communication between the air-bladder
and the oesophagus.

The proportional size of the organ, or the quantity of air distending it, on
which its size, no doubt, very much depends, varies, it would appear, in different
fish of the same species, and still more in those of different species. Commonly,
I believe, the bladder of the migratory kinds, as the salmon and white trout, is
smaller or less distended than that of the common trout and charr. Ina fresh-run
salmon of about 12 Ibs. taken with the net in the first week of August at Bally-
shannon, opened half an hour after its capture, I found in its bladder only about
a quarter of a cubic inch of air. And one of the men, an intelligent person be-
longing to the fishing establishment of that place, who, this last season, had, he
said, opened about two hundred fresh-run fish, varying in weight from about 8 to
28 lbs., assured me that, as well as he could remember, the quantity of air was
“ oftener under than over half a wine-glassful.”

For the purpose of chemical examination, of course, it was necessary to open
the fish under water. The contained air, extricated on puncturing the blad-
der, was collected in a graduated tube. For carbonic acid, it was tested by agi-

VOL. XXI. PART. II. 3U

246 DR DAVY ON THE SALMONIDZ.

tation with lime-water with excess of lime. The proportion of this acid gas was
in every instance small, barely a trace. For oxygen the test used was a stick of
phosphorus, left exposed to the action of the air some time after it had ceased
to fume, or the air to suffer diminution. In the instance of the salmon mentioned,
the diminution from the action of the phosphorus was hardly appreciable. The
same remark applies to the air of the bladder of the white trout : it was tried in
two instances,—fish of about half a pound caught in the Claudy river in Donegal.
In the trout, river-trout, fish of about a quarter of a pound (two were examined),
the proportion of oxygen was greater; it amounted to about ten per cent. of the
whole volume of air.

As these trials were mostly conducted when on fishing excursions, and under
circumstances nowise favourable for minuteness of research, the experiments I have
made on the air were chiefly limited to those above described, which sufficed to
convince me that the air of the air-bladder was principally azote, and to allow the
inference that the trace of carbonic acid was most likely rather accidental than
essential, owing probably to the secondary action of the minute proportion of
oxygen present on the organ itself.

These results, I may remark, accord with those obtained by former inquirers
on the air of the air-bladder of several other fresh-water fish, whilst they differ
so greatly from others—those afforded in like trials on deep-sea fish,—the air of
the air-bladder of which was found to be principally oxygen.

That the same organ should secrete two gases so very different in their na-
ture, appears anomalous, and deserving of further inquiry. Indeed, does not the
entire subject need more minute inquiry? At present, the facts relating to it are
few, and seem far from adequate to allow of any satisfactory conclusions being
drawn as to the use of the bladder and its secretion in the animal economy, ex-
cept of a mechanical kind, as affecting the specific gravity of the fish. Were the
gas uniformly of one kind, were it constantly azote, it might be easy to assign it
a plausible end; the function of the air-bladder might be inferred to be auxiliary
to that of the kidneys. The secretion of oxygen is the anomalous fact, so contrary
is it to the ordinary course of changes in living animals, in which the general
tendency is to the consumption of oxygen. A priori, one might almost as much
expect oxygen to be exhaled from the lungs in respiration, as to be separated from
the blood by secretion by the air-bladder; and, had we not the authority of so
accurate an observer as M. Biot, we might be led to suspect that the statement
of its being so was founded in error.

2. Of the Abdominal Aperture of the Female.
In a paper on the impregnation of the ova of the Salmonide, which I had the
honour of presenting to the Society last year, I expressed the opinion that the
passage through which the ova have their exit is not constantly open; that after

DR DAVY ON THE SALMONIDZ. 247

spawning it becomes closed, but by a membrane so delicate as to be most easily
ruptured.

Since that paper was published, I have, from further inquiry, been led to
think that in forming that opinion I was in error, and that, strictly speaking,
though the passage is virtually closed, it is not absolutely; that is to say, there
is no membraue formed over it shutting it up, or union by adhesion, but merely
the contact of its parietes, the close apposition of the inner surface, in effect equi-
valent.

This conclusion I have arrived at from the examination of the part in the
salmon and the white trout, and the lake trout of a large size, during the spring
and early summer, when their ovaries were little developed. In all these fish I
found, on careful examination, that though air could not always be passed, even
when impelling it with considerable force, yet that a small probe, carefully ap-
plied, might be passed, and when the passage was laid open, without any appear-
ance of the rupture of an occluding membrane.

This admission does not appear to me to affect the argument against the im-
pregnation of the ova ab externo, deducible from the structure of the reproductive
organs, whether of the male or female fish ; the minute papilla of the one seeming
as totally unfit for intromission, as the somewhat larger and more prominent pa-
pilla of the other (the female) is to perform the part of a recipient.

It may perhaps be said, that when the ova are mature and fit to be impreg-
nated, the passage may enlarge and become patulous. But admitting this,
which I believe to be the fact, at the same time that it enlarges, it becomes more
vascular, its marginal glandulee more active, its fimbriee elongated, so as, whilst
favouring the exclusion of the ova, preventing the contrary,—admission of what-
ever kind from without.

In salmon fishing, early in March last spring, I took a salmon returning to
the sea. In the cavity of the abdomen a few ova were found of their full size, such
as they are when fit for impregnation; but they bore no marks of having been
impregnated ; there was no appearance in them of organic change; indeed they
were quite transparent, and when put into water, after a minute they became
opaque from the coagulation of their albumen, the effect of the imbibition of
water through their membranous shell. And, hence, may it not be inferred,
first, that no impregnation had been effected internally ; and next, that after the
exclusion of the greater portion of the ova, the abdominal aperture was virtually
closed and impervious.

3. Of the Breeding Localities of the Salmonide.
It is commonly believed that the several species of the genus, at least the
more distinguished, such as the salmon, white trout, bull trout, common trout,
and charr, require their ova to be exposed to the action of running water for their

248 DR DAVY ON THE SALMONIDZ.

fecundation and hatching; that, for this purpose, the migratory kinds quit the sea
for the river, the lake-fish the still water for the streams, and the river-fish their
ordinary places of abode for the smaller tributaries.

From such information as I have been able to collect, 1am led to infer, that
though this belief is commonly well founded, there are exceptions; and that the
conditions to successful breeding are not quite so restricted as has been generally
supposed.

In a former paper, which was honoured with a place in the Transactions of
the Society, entitled, “Some observations on the Charr, relating chiefly to its
generation and early stage of life,” proof was adduced that this fish more commonly
avoids than seeks running water for the purpose of breeding, and that the gravelly
and rocky shoals of the lakes it inhabits are its favourite breeding localities, ra-
ther than the bed of a river or brook, where the water is in rapid motion.

In artificial breeding, not only have the ova of the charr, but also of the com-
mon trout and salmon, been successfully hatched without the use of running water,
merely by changing the water daily. And in accordance with this, I have been
well assured of similar instances in nature, that is, of the ova of the trout and of
the salmon having been laid, like those of the charr, on beds of gravel in lakes, and
where it is believed they have been hatched. I shall mention the few instances
which I believe are worthy of credit. In Connemara, county Galway, Ireland,
there is a lake, about five miles from Clifden, called Lough Anaspick (The
Lake of Contention), abounding in good trout, and which, from its situation in a
flat part of the country, is fed more by the rain that falls into it, than by the
stream which enters it,—a stream so small as to be unfit for a breeding place,—
the same remark applying to the little outflowing stream. On a gravelly shoal
of this lake I have been assured by fishermen residing in the neighbourhood, that
the trout deposit their spawn, that they have been seen in the act, and that the
roe has been found there.

In Blea-tarn, in the Lake District of England, observations of the same kind
have been made. I have been informed that the roe of the trout has been de-
tected in plenty near the shore. The person from whom the information was
obtained remarked that such a laying of the spawn was unavoidable, inasmuch
as, from obstructing obstacles, the fish could neither run up nor down the inflow-
ing or outflowing stream. In this instance it was stated, that the favourite place
of spawning was near to the fall of the little stream into the tarn, its principal
feeder.

At Lough Melvin, in Ireland, a lake in which the gillaroo trout is plentiful,
I learned, whilst there, that this trout never enters the tributaries with the other,
the common trout, in the spawning season, and that it had never been seen in them ;
from whence the fishermen, my informants, who watched the streams, inferred,
with confidence, that it bred exclusively in the lake. But though confident of

DR DAVY ON THE SALMONIDA. 249

this, they had never, they said, found the ova,—which, indeed, is not surprising,
considering the great extent of the lake, and that they had never made search
for them.

The only instance I can mention as appearing to be well authenticated, of a
salmon spawning in a lake, I learned from an old Irish fisherman residing in the
neighbourhood of Lough Erne. He assured me that he had seen a pair of salmon
preparing their spawning-bed in a shoal of the lake off an islet known by the
name of Rabbit Island.

_If what I have stated should be received as satisfactory, I hope it may prove
not without use, as tending to show that the Salmonidze may be bred in lakes
and ponds; and thus encourage attention to these as breeding places,—for in-
stance, in ponds, by providing beds of gravel, and in lakes, where fish are known
to spawn, by affording protection from the depredation of the poacher, which, in
the instance of the charr, we know, from experience, to be much needed in some
of our Westmoreland lakes.

4, Of the Variable Time of the Hatching of the Ova.

In a paper already referred to, that “On the impregnation of the ova of the
Salmonidee,” mention is made of the successful result of impregnation in the in-
stance of the mixing together of the roe and liquid milt of the charr obtained
from the living fish.

The roe, after having been thus brought into contact with the milt, was divided
into three portions. One, the largest, was placed in an earthenware pan, about
two feet in diameter, in which was a stratum of gravel taken from an adjoining
brook, and water, soft spring water, to the depth of about three inches, which
for the most part, about two-thirds, was changed daily. The ova were laid on
the gravel, and the vessel was placed on the floor of a room without a fire, where
the temperature was liable to little fluctuation.

Smaller portions were put into two water or finger-glasses, such as are used
at table, about four inches in diameter, in which also gravel of the same kind
was laid, with water from the same spring to the depth of about two inches, and
which, as in the first mentioned, was in great part changed daily. Both glasses
were placed on a stand about three feet from the ground, and within a few feet
of the pan, and all three were exposed to about the same degree of light.

The experiments were commenced on the 25th of November. On the 8th of
January, in each of the glasses, three young fish were found in the morning at
large, excluded during the preceding night. Onthe 9th, more had made their
appearance in the upper vessels, but none in the one below. The temperature of
the water in the glasses was 50° Fahr., that of the water in the pan on the floor
being 48°. On the 10th, many more young fish were produced in the glasses, but
ene ovum only was found hatched in the Pan: On the 13th, whilst no more had

VOL. XXI. PART II. ax

250 DR DAVY ON THE SALMONIDZ.

appeared in the lower, all but one egg were hatched in the upper, and that one
proved to be dead. On the 20th, and not till then, another egg, the second, was
hatched in the pan. On the 22d, it is noted that many more were hatched dur-
ing the twenty-four hours, the temperature of the water being about 52°. From
the 22d to the 31st, the hatching process continued, a few young fish appearing
daily. Those last produced, it was observed, were smaller and feebler than the
first, and died in larger proportion.

It is worthy of note—such was the remark made at the time—how, under the
same circumstances, as in the water-glasses, or under slightly different circum-
stances, as in the earthenware vessel on the floor, ova from the same fish, im-
pregnated with the same milt, at the same time, differ so much as to the time of
being hatched, the size of the fcetal fish, and their vitality both before and after
exclusion, some embryos dying in the egg, some in an advanced stage in the act of
extricating themselves, other young fish at intervals of hours or days.

Now, what was witnessed in these experiments, it can hardly be doubted oc-
curs in the natural process of hatching, in which the circumstances commonly
must be very much more varied, and the results, it may be presumed, equally so,
and not without advantage as regards the preservation of the species.

5. Of the circumstances and agencies likely to exercise an influence on the Young Fish.

In the paper before referred to, ‘‘ Observations on the Charr,” a section was
given to the subject above named. The inquiry was, as it appeared to me, an
interesting one; and it was my intention to prosecute it farther, but hitherto
I have done little for want of opportunity, and that is comprised in two trials,
one on keeping the young fish excluded from light; the other on placing them in
a very small quantity of water, barely sufficient to cover them.

The first trial was commenced on the 31st of January. On that day, one of
the water-glasses, with its brood of young charr, was placed in a dark cupboard,
from which light was entirely excluded. Here they were kept till the Ist of
April; during which time the vessel was taken out only once daily, for the pur-
pose of changing the water and giving food, which occupied no more than a minute
or two. Now, comparing them with the brood in the other water-glass, which
had been daily exposed to the light, I could perceive no well-marked difference
in the appearance of the fish as to form, colour, progress of growth, or activity.
The only difference noticeable was, that those kept in the dark were much shyer
than those exposed to light, which was indicated, on their being brought to
light, by their endeavouring to hide themselves; this they did by thrusting the
head under the gravel.

The other trial was made on the 13th and 17th February, with healthy young
charr, hatched between the 8th and 10th January, and on the 10th March on a
young salmon hatched about the 26th February. On the first-mentioned day a

|

DR DAVY ON THE SALMONIDZ. 251

young charr was put into a platina capsule about I? inch across its brim, with just
sufficient water to cover it. It remained active fifty-two hours ; and it may have
been active longer, as it was found dead in the morning, the night hours not being
included in the time specified. In the second experiment, the young fish simi-
larly treated lived rather more than seventy-four hours. The capsule, it may be
mentioned, was covered with a slide of glass, to prevent rapid evaporation, and
yet not exclude air. In the third experiment, the young salmon was put into a
small liquor-glass, with a little water, little more than sufficed to cover it and
enable it to move freely, in weight no more than 47 grains. Left till the 22d;
during these nine days it did not appear to have suffered from being so limited
and confined. Returned on this day to the vessel from which it had been taken,
it seemed unimpaired in vigour and activity. The temperature of the water,
in each instance, did not exceed 52° Fahr., and was never below 48’.

These experiments, I need hardly point out, were made with the intent of
testing the power of endurance of young fish during periods of drought, when
they are liable, from the lowering of the streams, to be left almost dry.

The result of the last experiment, I may remark, was somewhat different from
what I had expected, supposing, as I previously did, that the air necessary for
supporting life would soon be exhausted in so small a quantity of water; not
taking into account that the motion of the fish (and it was very restless) might
promote the absorption of air; and that even the small volume of water so fully
exposed, and almost constantly agitated, would conduce to the same.

6. Of the Food of the Young Fish.

In consequence of the attention that is now being paid to the artificial pro-
cess, as it has been called, of breeding fish, the question, what kind of food is
most suitable to the young fish when it has to provide for itself, after the con-
sumption of the store laid up in the vitelline sack, becomes one of considerable
interest.

My own experience as regards the attempt to feed the young fish, is very
limited. The first trial 1 made was with finely-grated boiled beef; the second
with dried charr—the muscular part dried rapidly and pounded very finely. <A
small portion of each was given daily to a different brood. The young fish fed
on the particles greedily, seizing them chiefly when in motion. Those which had
the charr seemed to thrive somewhat better than those fed on beef; more of the
former attaining their perfect shape, as denoted by the development of the fins,
than of the latter. In a third trial no food was given. This was in the instance
of the brood hatched in the larger vessel, the earthenware pan, in which was a
considerable quantity of gravel and small stones, with the addition of some aqua-
tic plants from the river Brathay,— that part of it which is one of the breeding-

252 DR DAVY ON THE SALMONIDA.

places of the charr. In this instance the young fish, after the disappearance of
the yolk, throve well, and, as I believe, chiefly on the infusoria present. This in-
ference was made partly in consequence of finding, on microscopic examination, in-
fusoria on the plants and stones and sides of the vessel, and vestiges of them in the
excrements of the young fish, and in the intestine of some that were opened, and
partly from observing how the young fish, when in pursuit, as it was supposed,
of food, seemed to confine themselves to the spots where the infusoria were in
greatest numbers. Another reason (were we to reason @ priori on the subject)
might be assigned, viz., the presumed fitness of these microscopic animalcules for
the food of creatures of so small a size as the young of the Salmonidez in their
early stage, and the fitness of the latter, with their microscopic eyes, to see and
make the infusoria their prey.

The fish, the subjects of these trials, were all young charr. Those from the
egos impregnated on the 25th of November were so advanced by the second week
in April, as to be considered fit to be set at liberty. Some were taken to a lake
in the Highlands of Perthshire ; others to a mountain tarn in this neighbourhood.
Both sets were from the earthenware pan, to which no food had been given.

I may offer as a suggestion, that where minnows abound, their young, it is
probable, may be employed as a useful aid for the support of the young of the Sal-
monidee. The time of breeding observed by the minnow, early in May, seems
suitable, and especially so the minuteness of the ova of this little fish, and of their
fry when hatched. Their eggs at maturity I have found to be ‘06 of an inch in dia-
meter; the foetal fish on quitting the egg was about 20 of an inch in length, and
no more than ‘35 inch when of its perfect form, as denoted by the growth of its
permanent fins, which it acquired in a few days. In this stage its weight (moist)
did not exceed ‘03 grain, and when dried was reduced to ‘01 grain! *

7. Of the Parr.

As discussion, wherever doubt exists, is always useful, so that it be tempe-
rately conducted, and lead to further inquiry, I venture to bring under the notice
of the Society the question, the vexed question, whether there be or not a fish of
the family of the Salmonide, a parr having so close a resemblance to the salmon
fry as to be with difficulty distinguished, and yet a distinct species.

* The above results were obtained in the month specified. The eggs were from minnows from
the river Rothay, a tributary of Windermere. On the 6th of May, they were impregnated by the
artificial process, and placed in water, varying in temperature from 50° to 54°, which was changed
daily. One feetal fish burst its shell on the 11th of May; the next on the night of the 12th; the
majority on the following day ; some did not appear till the 15th. On the 31st of the same month,
most of them had acquired their permanent fins.

In substance, the eggs of the minnow were found similar to those of the Salmonidz, being com-
posed of oil globules, and of an albuminous fluid, coagulable by admixture with water.

Some of the ova to which no milt was added—the omission intentional—died without showing
the slightest appearance of organic development.

DR DAVY ON THE SALMONIDA. 263

So far as the weight of authority is concerned amongst naturalists who have
given their attention to the subject, I believe it is in favour of the negative; and
on the ground, first, that the parr, according to their experience, has never been
found in a river inaccessible by the salmon or sea-trout; and, secondly, that no
reliance apart from this is to be placed in slight difference of form, or of colour
or spots, as these vary in the known fry of the salmon, according to the quality
of the water, food, and other infiuential circumstances, and in themselves, there-
fore, are insufficient to constitute a species.

The few who are opposed to this view, and who maintain that there is a parr, a
distinct species, state that though rare, yet such a fish is to be met with in streams
where the salmon and sea-trout have never been seen, and in some in which they
assert it is impossible that either could resort, inasmuch as the access to them is
prevented by impassable falls. Two rivers I have heard named as coming under this
category, in which it is said that parr have been caught above falls that no salmon
or white trout could by any possibility surmount,—one a tributary of the Shin, in
Sutherlandshire, the other the Kirkiag, in the same county, on its west coast.

Granting the fact that in each of these rivers there is an impassable fall, is
the inference drawn by the advocates of the distinct species quite conclusive ?
May not the parts of the river above or below the fall have some communication
by a channel through which a salmon or sea-trout might be able to pass, either
subterraneous, or by some collateral branch formed during a period of flood ?
or, if nothing of the kind be discoverable on careful examination, may not the
parr found in the upper stream derive their origin from impregnated ova of
the salmon or sea-trout conveyed by birds, such as the water-ouzel, adhering to
its feet or plumage, or loose in its bill? Thus conveyed, it is presumed they
would retain their vitality, and in due time be hatched. There is a well-authen-
ticated instance of impregnated ova of the salmon, taken even from the stomach
of the common trout, having produced salmon-fry.

But waving these arguments pro and con, what is the evidence that all parties
would probably hold to be satisfactory or conclusive? Is it not the showing that
the parr, the asserted distinct species, propagates its kind, and that in due sea-
son, and at the same time, the male and female fish are to be found with roe and
milt mature,—the one of its maximum size, loose in the cavity of the abdomen,
fit for exclusion,—the other in its liquid milky state, ready for expulsion ?

So far as I can learn, such a coincidence has never been observed. I have
examined hundreds of parrs, and a large number from a river where the salmon is
rare, and is never known to be taken but by the poacher in the fall of the year,
after a flood. Male parrs I have frequently found with mature milt, but never a
female with roe correspondently developed; on the contrary, in the female fish,
without exception, the ovaries have been so small, that had they not been sought

VOL. XXI. PART II. 3 Y

254 DR DAVY ON THE SALMONIDA.

after carefully, they would have escaped notice, and the ova contained in them
so minute as to be mere granules.

In conclusion, is it not reasonable to hold, that till such evidence as that re-
ferred to be adduced and clearly substantiated, the existence of a parr as a distinct
species must be considered as not proved.

LESKETH How, AMBLESIDE, November 22, 1854.

( 255 )

XVI.—WNotes on some of the Buddhist Opinions and Monuments of Asia, compared
mith the Symbols on the Ancient Sculptured “ Standing Stones” of Scotland.
By Tuomas A. Wisz, M.D., F.R.S.E. (With a Plate).

(Read 2d January 1855.)

The general identity, in idea and design, of the ancient monuments of Southern
and Western Europe, with those of Hindostan, is so marked, as to appear to justify
the inference that races of Asiatics proceeded westward at different ages, and
established themselves along the shores of the Baltic and Mediterranean Seas, and
part of the Atlantic Ocean; along which route they have left characteristic monu-
ments, which resemble those of their original country.* The ancient monuments
common to these distant regions are—

1. Cairns and Barrows. These monuments, common to Celtic Europe and
India, are mounds of earth, or piles of stones. One near Hidrabad, in Central
India, was surrounded by a circle of stones, which exactly resembled those round
cairns in Europe.

2. Cromlechs and Kist-vaens, consisting of two or more upright stones, which, as
props, support a horizontal block or slab, forming a chamber underneath. Such
monuments are pretty numerous in wild and retired
places in the peninsula of India(fig. 1), and contain a sar-
cophagus, with the bones of the dead.+ In others, urns
are found, of red or black pottery, containing the ashes
of the bodies which had been purified by their passage
through fire. These monuments were usually paved
with a large slab, and have a circular holet in one of
the upright slabs which formed the walls, to allow the
passage of the soul, which was supposed to linger for
a time near the remains of the body after death. These
cromlechs were in some cases varied in their shape, and

* These eastern races appear to have proceeded westward by Scythia and Scandinavia, on the
one hand (Worsaaz, Primeval Antiquities of Denmark, edited by Mr Tuoms, p. 182 et seq.); and by
the shores of the Mediterranean, on the other. Hence, we find the same cromlechs and cinctures of
pillar-stones on the mountains of Circassia, and the undulating plains of Tartary (Dewnis’s Etruria,
vol. ii., p. 321); Asia Minor (Insy and Manexxs’s Travels, ch. vi. : Colonial Libr. Edit., p. 99); Tunis,
in Africa (Dennis, J. c.); Etruria and Sardinia (Dennis, ibid.); the Atlantic shores of Spain (Bor-
row’s Bible in Spain, ch. vii.); of Gaul (Histoire des Peuples Britons, par Courson); and the
greater part of the British Islands.

~ Colonel Mackenziz sometimes found in these cromlechs urns, arms, and even coins. See
Maria Grauam’s Journal, p. 168.

t See Letter by Capt. Newszotr, Asiatic Society, 17th July 1846.

VOL. XXI., PART II. oz

256 DR THOMAS A. WISE ON THE

the slabs were dressed. In one found near Rodroog (fig. 2), by the late Col. Mac-
kenzie, Surveyor-General of India, there was an attempt at sculpture; proving a
certain advance in ornamental art. Sometimes they were surrounded by circles
of stones.

3. Obelisks, or as they are frequently called, Standing Stones. Such large
tapering, erect stones, or obelisks, are found in all Celtic countries, and resemble
topes or solid cairns in Buddhist countries; one kind being funereal, erected over
the grave of an individual; another, memorial, to commemorate some event ; and
a third being dedicated to the Deity. In general, such stones are placed over the
dead in the Celtic countries of Europe, and are likewise found in Central India, as
well as in Bengal and its neighbourhood. The
drawing (fig. 3) represents such stones, as
found in Central India by Col. Mackenzie.
What renders this monument interesting is,
that it appears to have formed part of a
cairn similar to that mentioned above, which
was surrounded by a circle of stones. In -
many parts of India, however, such large ;
blocks of stone are not to be procured; and py-
ramidal structures, spires, or “‘ muts”’ (fig. 4),
evidently modifications, under the pressure of circumstances, of the original mono-
lithal erection, were had recourse to. These are still erected by Hindus. They
are sometimes cenotaphs, at other times mausoleums. In the former case, the
wealthy erect these buildings as memorials of the dead; and in the latter, over
the ashes of their relations, or over a bone of their body, after it has been purified
by fire, on the banks of a sacred river. In this way each of the Maha-rajahs of
Tipperah has a spire (fig. 4), erected over a bone of his predecessor, on the banks
of the sacred Teeta River. A favourite wife, particularly if she had become a Suttee,
had often a mut erected over some of the ashes of the body. In these cases the
spires were usually smaller than those over the husband. These muts often con-
tain an image of Siva or Kalee; others contain a /inga (priapus), or a flat stone
supporting a central pillar, representing the regenerator Siva, or Nature under
the male and female symbols. These buildings are varied according to the means
and the taste of the individual. In general, they consist of one, but in other cases,
of many spires.

4. Circles of Stones. The circles of stones appear to have formed sacred spots,
intended for other purposes besides that of being depositories for the remains of the
dead. Of these, examples were found in the same retired places as the cromlechs in
Central India. They are often of the same size as in this country, and, like them,
are formed of boulders. One, of which a drawing is now before me, forms a circle of
32 feet; another of 26 feet; and a third is 30 by 274 feet. Asthe arts improved in

ea (i tt a ea ieee

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 257

Europe, the light of Christianity was also introduced, and the erection of these struc-
tures was abandoned. But in India, where idolatry held its ground, the arts, as
they advanced, were employed in their enlargement and embellishment. The ob-
jects and edifices of superstitious veneration were increased in size, until they at-
tained the scale which we see exemplified in the remains of the vast structure of
Depaldinna, the Hill, or Mound of Light, near Amrawatty, in Central India. There
We see immense excavations, surrounded by concentric circles, formed of vast num-
bers of stones, beautifully sculptured with mythological figures, and inscriptions
in two or three different idioms of the Sanscrit language. The outer circle of this
gigantic structure is 160 feet in diameter. In the neighbourhood are numerous
remains of kist-vaens, circles, barrows, &c.

Some years ago I examined two interesting structures or temples, which had
all the essential features of the stone circle, and of the ancient temples of Central
India. They are situated near the banks of the sacred Bargaretta, or Hooghly
River, at Culna, and belong to the Maha-Rajah of Burdwan. In this temple there
are two concentric circles of stones in marble, formed into 108 lingas, or repre-
sentations of the male and female energy of the world, with a temple over each.
The external circle is formed of alternate white and black marble pillars; the in-
ternal circle entirely of white marble. The outer circle had its entrances north
and south, and the inner east and west, much in the same manner as in the large
temple of Depaldinna, in Central India; and while in the centre of this there was
a tank, the temple in Bengal, where worship is regularly celebrated, has a well
of water, the yoni, or symbol of Parvati, the female energy. A second circle of
temples in the neighbourhood appeared to be merely a modification of the other.

This general identity of the ancient monuments of southern and western
Europe with those of Hindostan, is further proved by the physical conformation
of the races who inhabit these distant countries, by the similarity of many of
their manners, customs,* and observances;t and by the decided and extensive
affinities of the Celtic and other languages of western Europe with the San-
scrit,t which afford as strong evidence as we can be expected to obtain, of a
connection so remote between races so widely separated. Indeed, the names of
mountains, rivers, and other great natural features of the south and west of
Europe, bear evidence of its having been in possession of a Celtic race anterior to
the earliest date of authentic history; and this early connection indicates a line
of inquiry, by following which much of the obscurity resting over the earliest
monuments and history of western Europe may be cleared away.

As these Asiatic races emerged from their oriental seat, and settled on
the shores of Europe at different stages of advancement in civilisation,
we must expect differences in the idioms of their language, in their monuments,

* Primeval Antiquities of Denmark, p. 132 et seq.
¢ Pury, Nat. Hist., xxv. 1. t Pricuarn’s Celtic Nations, pp. 20-22.

258 DR THOMAS A. WISE ON THE

and in certain of their observances; which will be better understood by adding a
few remarks on the Asiatic people who are believed to have erected these monu-
ments, and on their religious opinions, in explanation of some of the symbols or
hieroglyphics which are found upon the ancient obelisks of Scotland.*

A reformer of the Sabaism, and Brahminical fire-worship of the ancient
Asiatic races, gave rise to the present form of the Buddhist religion, in the north
of India, in the sixth century before the Christian era. This religion inculcated
a belief in a trinity, in the perfectibility of our nature, in the transmigration of
souls, in the veneration for serpents, for certain trees, &c.; and such was the sane-
tity and zeal of the priests, and the benevolence of the doctrines they inculcated,
that it rapidly spread over Hindostan. Some time after the invasion of India by
Alexander the Great (B.c. 247), Asoka was the great Buddhist monarch of that coun-
try, who probably propagated the new doctrines by recording edicts upon rocks, and
pillars (lats), in different parts of Hindostan.+ As the language was the vernacular
dialect of the period, it varied according to the part of the country it was intended
for; and it was only by the genius of the late James Prinsep that it was deci-
phered.{ These most interesting monuments of antiquity are found in distant
parts of India, and were most probably transcribed from copies obtained from the
king, and such changes were made as were required for the better understanding
of the people for whom they were intended. ‘They inculcate the following bene-
volent precepts: honour to parents and kindred; never-tiring charity; respect
and liberality for good men, and spiritual guides ; temperance and moderation in
every word and action; and the utmost humanity to man and the inferior animals.
These precepts were not only to be inculcated in their own country, but ministers
of religion, or missionaries, were appointed ‘‘ to spread them, and to intermingle
themselves among all unbelievers, to overwhelm them with the inundation of re-
ligion, and with the abundance of the sacred doctrine.’—(5th Table.) They were
directed to effect conversions in the dominions of Alexander (satrap of Persia),
Antigonus (sovereign of Phrygia and Lycia), Magas (the son-in-law of Ptolemy
Philadelphus), Ptolemy (either the first or all of the four first princes of Egypt), and
Antiochus (the Great). These names were probably given, as Professor Wilson
supposes, from their notoriety in India, as they were not contemporaries.§¢ The
missionaries were to find their way into the uttermost limits of barbarous countries,
for the benefit and pleasure of all, and for reducing the passions of the faithful,
and for the regeneration of those bound in the fetters of sin; “ intermingling

* See the beautiful drawings of the ancient sculptured stones of Angus by J. Cuatmers, Hsq.,
and the more recent volume on those of Scotland by the Spalding Club.

+ On the Kapur di Giri, the Girnar rock Gujerat, and on the Dhale rock of Cuttack; on the
Pillars (lats) of Delhi, Allahabad, &c. See Journal of Asiatic Society, Calcutta, vol. vii., pp. 156
and 219. ere

t See Asiatic Journal, Bengal, vol. vii., pp. 150 and 219.

§ Journal of the Royal Asiatic Society, vol. xii., p. 246.

4°" Vert fe Se

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 259

equally among the dreaded and the respected, both in the very metropolis of
religion (Pataliputa) ; and in foreign places,” to teach them “righteousness, which
passeth knowledge.”

The Buddhists were then a powerful and arich community; and in the fifth cen-
tury, the Chinese traveller Fa Hean* found Buddhism the prevailing religion of In-
dia. But in the middle of the seventh century, another Chinese traveller (Hwan
Thsang) found that the zealous Buddhists had degenerated into rich, selfish, and
idle monks. This engendered a feeling of dislike and jealousy among the people,
and as they rejected the sacred books of the Hindus, and many of their cherished
dogmas, the Brahmins persecuted them with relentless fury, and after ages of san-
guinary wars, they were expelled from India. The vanquished Buddhists fled to
Ceylon, and other neighbouring countries; and the feeble remnant in Hindostan
live in small communities, abstain from carnal pleasure, and pass a monotonous
existence in the routine of a monastic life, without any of that fervid enthusiasm
for which their predecessors were once so distinguished. But although so few
remain in the original seat of the religion, so great was their success in other
countries, that there are now upwards of three hundred millions of Asiatics who
profess the Buddhist religion.

One cause of the almost total extinction of Buddhism in India was, that it re-
quired its followers to lead a life of charity, abstinence, and privation, with a long
course of prayer, penance, and devout abstraction, in order to work out their escape
from the circle of existence ; or to attain what they considered the state of beati-
tude in another world. This produced constant disputes and divisions, which,
with their wandering habits, the frequent and cruel persecutions, and the pre-
cepts of their religion, induced them to visit distant countries, to gain followers
to their peculiar opinions, which they modified to suit the people they visited. At
this period some intercourse was still maintained between the cognate, but widely
separated races; and the new doctrines were carried westward by missionaries,
who, finding some of the races they visited unprovided with a written language,
had recourse to symbols, already used in the East, to express their fundamental
doctrines. These were modified to suit the particular circumstances of the people
they resided among. ‘The Asiatics were idolaters from an early period, and have
continued so; and from their power and riches, and a certain advancement in the
arts, they constructed magnificent temples, and idols of Buddha; while they relied
on symbols among the rude tribes of Britain. Such differences in the method of
propagating the religion must be expected, and seem to strengthen the argument
in favour of their identity; and an enumeration of the remains of the interesting
race in India, will afford useful indications of their opinions. These are—

1. Magnificent Cave Temples, excavated out of the solid rock. Some of these
are beautifully decorated with paintings and sculptures.

* See the admirable translation, and most interesting notes, by J. W. Latptay, Esq. Calcutta, 1848.

VOL. XXI. PART I. 4A

260 DR THOMAS A. WISE ON SOME OF THE

2. Ldts, or sandstone obelisks, containing inscriptions of royal edicts regard-
ing ceremonial observances, &c.

3. Large Monasteries. And,

4. Topes, or religious edifices. These are in the form of massive hemispheri-
cal domes, and are another name for regular built Cazrns, signifying a solid
mound or tumulus. These Topes are either funereal, memorial, or are dedicated
to the deity.

a. The Funereal Topes, or Cairns, are the receptacles of the ashes and bones
of saints, and are built in honour of mortal Buddhas. They are of all ages, and
made of different materials; as they were the common form of tombs, even be-
fore the advent of the most celebrated mortal Buddha (the Sakya Muni), who
died B.c. 5438.

b. Topes were built as Memorials, in celebrated places.

c. Dedicatory Topes were intended as offerings to the Deity, the supreme invi-
sible God. These religious edifices contained no deposits, and were typified on
the outside by a pair of eyes on each of the four sides either of the base or crown
of the edifice, * to indicate the all-seeing, all-powerful, divine spirit, who is light,
and is supposed to occupy, in a special manner, the interior.+}

The great doctrine of the Buddhist religion consists in a triad, “ ti-ratna,”
or three jewels, or three precious ones; that is, Buddha, spirit or God, Dharma,
the law, and Sangha, the Buddhist community or brotherhood. This was the
genuine sense of the words, to certain of the initiated; but a more clear and in-
telligible explanation was, that Buddha signified the spiritual, or the divine in-
tellectual essence of the world, or the efficient underived cause of all; Dharma, the
material essence of the world, the plastic, underived cause; and Sangha, which
was derived from and composed of the two others. This third member is, there-
fore, the collective energy of spirit and matter in the state of action; or “the
embryotic creation, the type and sum of all specific forms, spontaneously evolved
from the union of Buddha and Dharma.” { This is merely a modification of the
opinion of so many of the ancient nations, and nearly all the Asiatic races of the
present day. They believe in a spiritual deity and a fruitful earth; in a male and
female principle, in mind and matter; Osiris and Isis; in Venus Genetrix and
Phallos; Pater ther and Mater Terra; Lingam and Yoni, Brahma and Sarsas-
wete, and other gods and their saktes or wives; Yang and Yin (Chinese), &c.

The Buddhist missionaries found it necessary to employ symbols in Asia and
in the countries they visited, in order to direct and fix the attention of rude races
to the spiritual objects of their worship. Those symbols of the deity were in Asia—

1. Spirit (Buddha), represented by a circle or wheel, typical of the passage of
the soul through the circle of existence.

* See Plate, Fig. 10, Cunnincuam’s Topes of Bhilsa, p. &
+ Journal of the Asiatic Society, Bengal, vol. v., p. 81. t Ibid., vol. v., p. 37.

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 261

2. Inorganic Matter (Dharma) was represented by a circle, or by a monogram
formed of the initial letters of the names of the elements of matter.

3. Of Organized Matter (Sangha), by a third circle, which, when decorated,
was often formed of the combination of the symbols of Spirit and Matter; or on
coins by the representation of an organized body.*

The symbols of the Buddhist triad, when employed in India, are often of ele-
gant forms, and gracefully decorated ; and have undergone various modifications
upon coins and sculptures, in different ages and countries, according to the fancy
of the individual, and the particular Buddha, or saint, they worshipped. Buddha
is represented by various-shaped wheels, Dharma by changes in the beautiful
monogram, and Sangha by a combination of the two others, by organized bodies,
or by other varied and graceful ornaments, to reach the understanding of those
for whom they were intended. As the community increased in power and riches,
they erected magnificent temples, or excavated them out of the “living rock,” as
the proper offering to the deity; amidst a profusion of ornaments and magnifi-
cence, idols, or dedicatory Topes (chaitya), were the objects of worship.

When the enthusiastic Buddhist missionaries reached the extreme west, they
found themselves among a rude race, at enmity with their neighbours, and me-
naced by the great Roman power, which had subjugated their more powerful south-
ern neighbours. These missionaries, with the Druids, many of whom had fled
from the cruel persecutions of the Romans, would unite the different tribes to
oppose their cruel invaders, and inculcate their religious doctrines. This could
only be done by symbols, as they had no written language; and upon the erect
stones, already probably venerated, they traced figures to explain their trinity, the
great dogma of their religion. As their influence extended, other obelisks were
erected, and adorned with devices to stimulate the pride of the Caledonians,
while they awakened their fears, and kindled their zeal, for their religious opi-
nions; and they were executed in a style which proved their intelligence, and
their knowledge of the arts which they had brought from the east.

In examining these symbols, we must expect that it is in the simplest form we
shall find the identity between the obelisks in Asia and those of this country.
Upon Buddhist coins, the triad is represented as triple hemispheres, most pro-
bably intended for circles: In the great temples of Ellora, and several other
Buddhist caves, Colonel SyKkes found these circles traced in the same order as on
the coins; two forming the basement, and one the apex (fig. 1).+ This is the
symbolical representation of the Buddhist triad; which is still more accurately
traced on the Kinnellar standing-stone, in Aberdeenshire, which has the three

* On the sculptured stones of Scotland it is represented by some embryotic form of animal or
vegetable life, or an imperfect circle.

+ See annexed plate (No. IV.), in which figures designate the oriental symbols, and letters those
on the engraved stones of Scotland. Journal of the Royal Asiatic Society, vol. vi., p. 451.

262 DR THOMAS A. WYSE ON SOME OF THE

circles placed in the same order as in the temples in Hindostan (fig. a); and to
mark still more intelligibly the trinity in unity, they are surrounded by another
circle. This is the simplest form of the representation of the trinity in unity;
and the “crescentic ornament” underneath the circles, in the Kinnellar stone,
proves its identity with the other sculptured stones of Scotland.* The most fre-
quent form, however, of the trinity on these stones, is two circles, symbols of
spirit and matter, united by a belt, and crossed by a bar, to the extremities of
which two sceptres were joined (fig. d), to indicate the supreme power, according
to the Buddhist creed, the co-ordinate, and all-originating principle. This formed
what has been called the “‘spectacled ornament” upon the stones of Scotland ;
while the third member of the trinity, organized matter (Sangha), was repre-
sented near the others, in the form of a crescent. Sometimes this third member
is crossed by sceptres, to indicate the sovereignty of the laws which organic mat-
ter follows.

This interpretation of the “ spectacled ornament” is further proved by the
frequent appearance of an eye at the angles where the cross-bar joins the sceptres;
which, like the eyes in the Buddhist temples dedicated to the deity, typify the
spiritual intelligence which rules the universe. I may refer to the smaller Aber-
lemno stone, as a good example of these eyes, as they appear on the standing-
stones of this country (fig. 10, a; and ka).

But neither the circles (fig. 1.), nor the crescent (fig. A, a), afforded a sufficient-
ly clear idea of organized matter, the third member of the trinity, which they were
intended to represent; and with that freedom which the Buddhist artists were
allowed, and took advantage of, they explained their meaning more intelligibly
by representing organized matter, in Scotland, as an embryo, or some rude repre-
sentation of animal life.+ Thus, on the Dunnichen stone, organized matter is re-
presented as a two-headed figure of a flower (c) gracefully bent towards the sym-
bol of God, from whence it was supposed to receive its spiritual emanation ; on the
silver ornament found at Norrie’s Law, a dog-like embryo (/), and on the Kintore
stone, the embryo of an elephant (¢) is thus receiving the spiritual influence. The -
same idea is expressed in the same way, on Buddhist coins; as is represented on
the annexed plate, where figs. 5 and 6 represent the union of the two members
of the trinity, spirit and matter («, 8), with an embryo elephant or monster below
(5); while organized matter was represented as a hand, an embryo (7), a serpent

* Ag the Hindus as well as the Buddhists suppose that the spiritual essence envelopes the earth,
I was curious to see if there was any difference in the size of the circles. I found the figures on the
Kinellar stone were sufficiently distinct to enable me to do so; and on carefully measuring the three
circles, I found that the upper circle, and that on the right-hand side, were of the same diameter,
while that on the left-hand was half an inch larger. I therefore consider that this circle represented
Buddha, or spirit.

+ According to this opinion, man is the union (Sangha) of matter (Dharma), with the soul or
divine intelligence (Buddha).

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 263

(7), a bull (8), &c., on other coins. This proves their identity with the symbols on
the stones ‘in Scotland.

Various other examples and modifications might be stated, but I shall now
only mention the interesting and solitary example of such symbols upon a rock
in Galloway. In this example, the sculptured “ spectacle ornament,” is near the
top of the rock, with organized matter in the form of a horn, having an orna-
mented large extremity or mouth, turned to the symbol of the deity, and from
what might be considered as its navel, two diverging lines proceed and termi-
nate in a circle, or embryo head (fig. m); whilst lower down another (8), more
formed and detached, is intended as a human head, with two feelers or antenne,
to communicate with the external world; by which means, the embryo was most
probably fancied to be developed to its full size and figure.

The serpent is represented on several of the engraved stones of Scotland, as
the symbol of the deity, or spirit ; and this bore allusion to objects of a divine or
intellectual nature.* It was therefore represented as transfixed by a cross-bar,
uniting the extremities of two sceptres (fig.); as on the stone of Belutheron
and of Meigle, over which an embryo elephant is the representation of crude
organized matter; which, like those near the circles, it was supposed to
typify.

In some cases the trinity is represented in the form of a horse-shoe, with or-
ganized matter in the form of a fowl (fig. z).

A third variety of the symbol of the spiritual deity is a sculptured square, or
oblong fork-like figure; a modification of the cross, or Buddhist sacred labyrinth.
This is the complicated form of the Buddhist cross (fig. 9), which forms a cu-
rious subject of inquiry, as it is found on ancient Phoenician pottery, and on
Gaza Coins; and is considered to be the Phoenician letter Tau (fig. 6), the sym-
bol of divine life.+ It is also found on Christian monuments,{ and on the dress
of a gravedigger in the catacombs of Rome.j In Scotland this cross occurs
in the fourth line of the Newton stone (fig. y). Such examples of squares, or
modifications of the Buddhist cross, are to be found on the Maiden stone, and on
the Abernethy and other stones (fig. 0, p).

On further examining these interesting sculptured stones of this country, we
find other symbols of the faith ofthe Buddhists. The veneration which they had for
certain trees affords a striking similarity, and appears to have given origin to their

* Physici vero serpentem spiritualissimum animal esse dicunt; itaque res divinas, per ser-
pentis naturam notabant.—Eusebius, Prep. Evang., li., c. 3.

¢ Raoul-Rochette, Mem. de l’Academie Royal des Ins. et Belles Lettres, tom. xvi., p. 312, et
Xvil., part 2, p. 329.

t Loe. cit., p. 302. Boldetti Cosservazioni, pp. 87 and 350. Lupi. (Epitaph 8. Sever. Mart.,

p- 11); and on a Christian sarcophagus described by Allegranza (Sacri Monumenti, Milan, 1577),
tab, iv. and vi.

§ Louis Perrets sur les Catacombes de Rome, vol. i., p. 30.
VOL. XXI. PART II. 4B

264. DR THOMAS A. WISE ON SOME OF THE

western name, Druid.* In the East several trees were considered sacred by differ-
ent Buddhists, according as their particular saint was supposed to have been born,
done penance, preached, and died, under the sacred shade of a particular tree:
Such are the Ficus indica, F. glomerata, F. religiosa, Mimosa serisha, &c. This
explains the variety of trees which appear on the Buddhist coins, according as the
dynasty or family who struck the coin were followers or disciples of the Buddha
or saint whose emblem they adopted. The secluded spots, and the size of the
tree, seemed to have decided the selection ; while in Europe the oak was chosen for
the same obvious reasons; and the secrecy of the forests of these fine trees was
well adapted for the performance of their mysterious rites. Figure 12 is an en-
larged copy of a tree on a coin springing out of a Buddhist pot or rail; and figure ¢
is a similar tree copied from the Eassie stone. The Farnell stone (fig. 7) has the
representation of a sacred tree, with two priests, probably performing religious
worship, standing on the rail, and between two serpents shedding their divine
influence over the holy place; very much in the same manner as devotees are
seen worshipping at a holy tree (fig. 4) springing out of the sacred rail, and each
branch surrounded by a spiritual halo.}

Besides lions (fig. «), camels (fig. 7), serpents, and marked sacrificial bulls
(fig. s), centaurs appear several times upon the erect stones of Scotland; and they
cannot be supposed to be an original idea of the artists of these stones, but point
to Greece, their supposed original country; and perhaps they were derived from
the mysterious Pelasgians, the druidical worshippers of the oak. The centaur was
typical of a barbarous devastator; and he is represented at the side of the cross
with other monsters, as on the Glammis stone. On the Meigle and Aberlemno
stones, the centaurs hold a battle-axe in each hand (fig. ¢),{ and are represented
as dragging trees after them, being typical, probably, of the destruction of the
druidical groves by the Roman troops. These sacred trees appear to have been
respected by the Caledonians after the introduction of Christianity, which ex-
plains their appearing in honourable positions on the same stones with the cross,
as in the Eassie stone; while the centaur is represented, in the lower and most
degraded part of the stone; and in the Aberlemno stone, a bar separates him
from the chiefs above.

These observations would be imperfect without a few words on the nature, pro-
bable age, and uses of these interesting monuments; which are so numerous in the
eastern coast of Scotland, so remarkable for the peculiar symbols they bear, and
the elegant manner in which these are often executed, in an age when the inhabi-
tants of the country, from all we know of them, were in a state of ignorance and

* The name in the Sanscrit language is dru, in the Greek drus, Welsh deru, Erse dair, a tree, —
or oak-tree.

+ From a bas-relief in the Museum of the Hon. East India Company, London. ;
t The artist of Mr Chalmers’s beautiful drawings has erroneously represented these as crosses.

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 265

rudeness. A few slight notices of their existence, are found in some of the ancient
national authors, and various absurd legends, in explanation of the origin of the
engraved stones, are all that remain of the remarkable history of these antiqui-
ties, which can now only be obtained from examining the figures on the stones
themselves.

These sculptured stones of Scotland are large in size, selected with skill, and
often brought from great distances. They were erected at convenient central
situations, the sacred symbols were traced upon them, and they were consecrated
for worship. So various were their decorations, and so modified their sacred sym-
bols, that out of nearly two hundred that are supposed to exist, there are not two
exactly the same. Such varieties prove that the artists were allowed a consider-
able liberty in these illustrations of their belief, so as to suit their own fancy, or
render them more acceptable to the people for whom they were intended. We
might suppose the individual who traced the symbols on the rock of Galloway
(fig. m) to be a zealous missionary, who availed himself of a rock cropping out
of the soil, to trace the sacred symbols of the Deity, with such additions as might
make them more intelligible to the ignorant people, for whom they were intended ;
as we find “rich and zealous Buddhists in Thibet, of the present day, who main-
tain at their own expense companies of priestly sculptors, who travel, chisel and
mallet in hand, over the country, engraving their sacred formula’’* upon the rocks
and stones. Such a practice, among the ancient Buddhists of this country, would
explain the number of the standing-stones in the east of Scotland—not with in-
scriptions, for the people they were intended for were ignorant of letters, but with
the sacred symbols of the Deity engraved upon them.

It was probably after the persecution of the Roman General, Suetonius (a.p.
59), and the destruction of the sacred groves of Mona, and other places, that the
Druids joined their brethren among the mountains of Scotland, when their superior
intelligence, and hatred of the invaders, united the Caledonians in offering that
obstinate resistance, and consolidating that Pictish kingdom, on the east coast of
Scotland and north of the Firth of Forth, which the bravery and discipline of the
Roman legions were never able to conquer. The extent and nature of the reli-
gious monuments prove that the Buddhists had enthusiastic followers; and as
the severity of the climate, and proximity of their enemies, prevented their form-
ing groves, they changed the manner of conveying instruction, in conformity with
new opinions from the East, so as to render it more simple and less mysterious.
This was accomplished by erecting standing-stones, which bore the symbols of the
objects of their worship, sometimes by themselves, and at other places in connec-
tion with circles of stones; as was the case with the Kinnellar stone, the stones

* Om mani padme houm,—(Oh! the prescious lotus, Amen).—Oh! may I obtain perfection,

and be absorbed into Buddha, Amen. See Travels in Tartary, Tibet, and China, vol. i., p. 194.
KuaprotH, Journ. Asiat., Second Series, vol. vii., p. 188.

266 DR THOMAS A. WISE ON SOME OF THE

of Kintore, of the wood of Crechie, and, most probably, of many others which have
been destroyed. It is probable, therefore, that the erect stones, with the sacred
pagan symbols of the Deity, were prepared during the first century.

At an early period, a remarkable change occurred in the religious opinions of
the Caledonians. They became believers in Christianity. This we know from the
crosses they erected still retaining peculiar ornaments, and pagan symbols;
proving that they had not entirely rejected their ancient opinions; as druidical
monuments were supposed to be purified from the contamination of heathenism,
by being carved with the figure, or altered in the shape of the cross. This change
of faith must have been facilitated by the Buddhist doctrine of the Trinity, and
the liberality of their sentiments regarding other religious creeds, which is still so
marked a peculiarity in Buddhist countries. “ We find,” writes M. Huc, “ many
of these Buddhist priests (lamas) attach the utmost importance to the study and
knowledge of truth ; and we find the same men coming, again and again, to seek
instruction from us in our holy religion.”* It appears to be this same liberality
of sentiment which is now opening a way to the Christianizing of the great Chinese
Empire, which produced a corresponding effect in the conversion of the Caledonians.

Such conversions must have been made at an early age, as TERTULLIAN, who
wrote his celebrated Treatise against the Jews (a.p. 209), affirms, as a known
truth, that ‘‘ those parts of Britain where the Romans had no access were sub-
jected to Christ,” or had become Christians.} Those early converts could not
communicate with their neighbours, in consequence of the constant warfare
with the Romans and other tribes which were not able to conquer the great
Pictish kingdom north of the Forth. Even the Meeatze, or Midland Britons, were
still idolaters when the Caledonians were Christians, which explains why the
Scottish deputies, in the famous debate regarding the independence of their
kingdom before Pope Boniface VIII, declared that the Christian missionaries,
who converted the Caledonians in the primitive ages, came directly from the
east ;{ and the account by Bens of the dispute between Bishop Cotman and
Witrorp.§ When the Bishop alleged the example of St John the Evangelist,
with all the churches over which he presided, for adhering to the Jewish custom
of keeping Easter, W1iForp declared that wherever the Church of Christ is spread
abroad the western form was kept, “ except only these and their accomplices in
obscurity ; I mean,” said he, ‘“ the Picts and the Britons, who foolishly, in these
two remote islands of the world, and only a part even of them, oppose all the
rest of the universe.” || Their missionaries seem to have proceeded directly
from one of the then congregations of Asia Minor, which were most probably in- —

* Travels in Tartary, Tibet, and China, vol.i., p. 65.

+ Britannorum inaccessa Romanis loca Christo vero subdida. Contra Judeos, c. vil.
t Innes’ Critical Essay, p. 620, and Civil and Eccl. Hist., p. 14. § a.v. 662.
|| Bev, Eccl. Hist., b. iti, ch. 25,

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 267

timately connected with Spain, which explains St Paul’s remark in his Epistle to the
Romans,* “ whensoever I take my journey to Spain I will come to you” (chap. xv.
ver. 24) ; “‘and I will come to you into Spain” (ver. 28). This proves that congrega-
tions of Christians existed in Spain in the first century, from whence, most probably,
the spirit of conversion early found its way to Britain. It is in vain to conjecture
by what means the Christian missionaries reached the northern part of Scotland.
The enthusiasm of these primitive Christians was quite sufficient to overcome
these obstacles; and the liberal Buddhists, open to reason, and eager for the ac-
quisition of truth, would be easily converted, and become enthusiastic followers
of the new faith. But, retaining their liberality of sentiment, they did not imme-
diately reject the symbols of the Deity which their more ignorant followers held
in veneration ; and we may still mark the changes which their feelings under-
went by those on the engraved stones. In all those erected after this period, the
pagan symbols were subservient to the Cross, and this became more and more
marked, until the symbols at length disappeared from the emblem of the Chris-
tian faith.

According to that able antiquary, Dr D. Witson, “the interlaced patterns, and
figures of dragons, serpents, and nondescript monsters, bearing a close and un-
mistakeable resemblance to the decorations of some of the most ancient Irish ma-
nuscripts, and several of the beautiful initials from the Book of Kells, an Irish MS.
of the sixth century, as engraved in Mr Westwoop’s Paleeographia, bear a close
resemblance to the style of ornament of these sculptures; while the interlaced
network on the case of the shield of St Maido, which Dr Petrie conceives can-
not be later than the eighth century, though less distinctly characteristic, and by
no means peculiar to Ireland, very nearly corresponds in its details to the orna-
mentation frequently introduced on the Scottish monuments.” +

There is much difficulty in determining on the age in which these crosses were
erected, as we have no direct evidence on the subject. From the peculiarity of
their form, of their decorations, and locality, they must have been prepared before
the dissolution of the great Pictish kingdom in the ninth century; and the
adoration of the cross appears to have been practised in the ancient churches, for
which reason the heathen, particularly Julian, reproached the primitive Christians
with this species of idolatry. This may be traced to a misapprehension of the ex-
pressions of the apostles and fathers “taking up the cross and following Christ—
of enduring the cross—suffering persecutions for the cross—should not glory save
in the cross.” The custom of making the sign of the cross may be traced to the
third, but most probably was used at a much earlier period. Constantine the
Great first used the cross, or token under which he fought and conquered, and is
supposed to have first erected crosses in public places. Others believe that it was
not until the Empress Helena found the true cross that it became an object of

«ADs 60) t See his Archeology and Pre-historic Annals of Scotland, p. 497.
VOL. XXI. PART II. 4c

268 DR THOMAS A. WISE ON SOME OF THE

adoration. This was a.p. 326, in the twenty-first year of the reign of her son
Constantine, the thirteenth of the Pontificate of St Silvester, and the first after the
Council of Nice. Previous to a battle or great enterprise, an anticipatory offering
to heaven was presented by the erection of a cross, as we find Oswa.p did pre-
vious to the battle he fought with CapwA.to in the seventh century. In this case
it was a cross of wood, OswA.p holding it till it was fixed in the earth, while his
soldiers kneeled around.* It was in the eighth century that, in compliance with
the teaching of Jonn or Damascus, the crucifix was considered the principal
object of worship, so that it is probable those stone crosses in the north of Scot-
land were erected before this period; and, from their being so different in their
form and ornament from those of Iona, they were probably erected by a distinct
set of missionaries from the east, at central situations, for affording instruction,
by the piety or remorse of individuals. From a consideration of all the cir-
cumstances known regarding them, I am inclined to suppose that these peculiar
engraved stones of the Pictish kingdom, with crosses, were erected in that native
transition period, from the fourth to the eighth century, when Pagan and Chris-
tian relics were so curiously mingled.

The large obelisk of Meigle (fig. w) may be instanced as an example of a
beautiful cross which occupies the upper part of the face, with monsters, and
unseemly objects on the lower and outer compartments. On the back is the
armed centaur dragging away the sacred tree, with the figures of monsters on the
lower parts ; above which is the representation of some local tradition, with chiefs
on horseback, accompanied with dogs, to indicate the state and rank of the
individuals, which they were intended to represent. Upon the St Orleans stone,
a beautiful cross (fig. y), turned to the east, occupies the face, while the pagan
symbols are on the upper part of the back of the stone; whereas on the Fordoun
stone, they are at the bottom of the cross, without the crescentic ornament, prov-
ing the discredit into which the emblems had fallen. This is still more marked
in the obelisk of Golspie, near Dunrobin, where the face represents a graceful and
chastely-ornamented cross, and the back a curious collection of pagan emblems
(see Drawing, by the Spalding Club). At the top, Providence is represented as
hovering over organized matter in the form of an embryo elephant. Under this
is aman armed with an uplifted battle-axe, threatening an animal marked for
a bloody sacrifice, as is still done in India. In his left hand he holds an open knife
over a fish—another emblem; under which is the pyramidal form of organized
matter, the third member of the trinity, and the usual crescentic sceptred orna-
ment, which he is in the act of kicking away from their position over the “ spec-
tacled ornament,” now in the lowest and most degraded part of the stone, and
without the sceptres, the emblems of sovereignty. At the bottom of the stone is
a nondescript animal, upon the tail of which the armed man rests.

* Bene, Eccl. Hist., ui, 2.

BUDDHIST OPINIONS AND MONUMENTS OF ASIA. 269

It is probable that soon after the erection of this obelisk the heathen emblems
disappeared from the stones as no longer respected, and may have given place to
the simple cross, one of which is built into the wall of the churchyard of Meigle,
with no pagan symbols or grotesque additions (fig. z). These sculptured crosses
were erected on the side of highways, and in central and convenient situations.
As Christianity extended we find St Columba erected them, at a later period, both
in stone and wood, in the Christianized part of the island, where the priest afforded
instruction to the people, and offered up prayers, before there were churches.*
This explains the old Gaelic word “ clachan,” which signified then the stone,
and not, as now, the church.

The great Pictish kingdom north of the Firth of Forth, in which these ancient
obelisks are found in such numbers, remained independent till the middle of the
ninth century ; but from there not being a succession of missionaries, and no pro-
vision made to enlighten the Caledonians, they declined in religious knowledge ;
so that when CoLumBsa visited that country in the sixth century in order to con-
vert them, he found their dialect so peculiar that he was obliged to employ an
interpreter.| This explains why the names of so many old places in that part
of the country, and of the Pictish kings, are neither Irish nor Gaelic. It also ex-
plains certain peculiarities in the forms of the cross they used as compared with
those of Ireland and Iona.

Were it considered necessary, other facts might be added in proof that in an-
cient times the same pagan opinions existed in this country as in India, and were
supplanted by the Christian faith from the east, to which religion and civilization
are again flowing back from the west.

These ancient “ standing stones” and beautiful crosses of Scotland have, until
lately, been totally neglected, and many owe their preservation to their having been
buried by accident or design. In other cases | found they had been, from ignorance,
designedly mutilated, or, through carelessness, had been allowed to be destroyed ;
and a still larger proportion had been removed from their original position, and
placed in exposed situations, without any protection. The consequence is that the
wet insinuates itself into the interstices, especially of the red sandstone, and in the
process of freezing and thawing, the fissures are increased, and the surface of the
stone crumbles away. I may instance the large and beautiful cross of Meigle,
and that at Golspie, as examples; and, unless measures are speedily taken, they
will soon be destroyed by the influence of the weather. Were the cracks filled up
with Roman cement, and the whole stone, when dry, saturated with boiled oil,
' it would arrest the destruction of these most interesting monuments of antiquity.

* Innes’ Eccl. Hist. of Scotland, p. 212.
+ This is expressly stated in more than one place by his biographer Apomnan.

270 DR T. A. WISE ON THE BUDDHIST MONUMENTS OF ASIA.

Explanation of PLATE IV.
The Eastern symbols are marked by numbers, and the Western, or those of Scotland, by letters.

Figs. 1 and 2 represent the Trinity ; fig. 1 occurring in the great Buddhist temples of India (Syxzs),
and fig. 2 on the Topes of Bhilsa (CunnineHam).

These are the same as the Trinity in unity, fig. a, on the Kinnellar standing-stone in Aber-
deenshire, and of « on the Dingwall stone.

Figs. 3 and 4 represent the members of the Trinity separate; a, 8, y, representing spirit (Buddha),
inorganic matter (Dharma), and organized matter (Sangha).

The same is repeated in figs. b and c, on the stones of Scotland, in a form less decorated.

Figs. 5 and 6 are two of the many varieties of the two members of the Trinity, Buddha and Dharma,
as represented on coins ;* and Sangha, or organized matter, as an animal, generally not com-
pletely formed—as an embryo elephant, a hand, an embryo (7), a serpent (7’), a bull (8), &c.

These symbols are very slightly changed in the stones of Scotland. The two members of
the Trinity are represented as circles, united by a belt, which is crossed by a bar uniting
two sceptres, the ensigns of sovereignty; and the third member, organized matter, is
represented as an embryo elephant, a flower (¢), an embryo dog (/), a serpent (g), a fish
(x), a bird (2).

Fig. m is the only example of the Trinity traced on a rock of Galloway. In this case, organized
matter is in the form of a horn, from the navel of which embryo heads proceed. When de-
tached, they apparently communicate with the external world by means of organ-like in-
sect antenne.

Fig. n represents a serpent, transfixed by a bar united to two sceptres, with an embryo elephant, re-
ceiving its influence from the symbol of the Deity.

Fig. 9 is the Buddhist cross.

I is the same cross, as it appears upon the ancient Pheenician pottery and coins (a a a a),
is considered to be the symbol of divine life, and to be the Phoenician letter Taw (8), This
symbol appears on the fourth line of the Newton stone inscription (y).

Fig. 11 is a more complicated form of the Buddhist cross, and is called the Buddhist labyrinth—the
symbol of providence ; of which p is a modification, as it appears on the stones of Scotland.

Fig. o is another variety of the symbol of Providence. There are several others.

Fig. 10 is the representation of a Buddhist temple, dedicated to the Deity ; which is indicated by the
two eyes (at a).

The same is represented on the stones of Scotland by two eyes (fig. k a), where the bar cross-
ing the belt, unites the two members of the Trinity, and joins the two sceptres: In this
the resemblance is complete.

Fig, 12. The sacred Buddhist tree, represented as rising out of a pot; which resembles that (q) on
the Eassie stone of Scotland.

Fig. 13. The sacred Buddhist tree, surrounded by a sacred halo, with two persons worshipping.

The same sacred tree is upon the Farnell stone, Scotland (fig. v), with a sacred serpent
on each side, and two figures standing on the pot.

Fig. s represents the sacred bull on the Eassie stone, marked like those still found in India.

Fig. ¢. The centaur on the Meigle stone, armed with two battle-axes, and dragging a sacred tree
after him.

Figs. w and v. The figures of a lion, and a stooping camel, on one of the Meigle stones.

Figs. w, y, z. Specimens of crosses as they appear upon the ancient sculptured stones of Scot-
land.

* See Journal of Asiatic Society of Bengal, particularly vol. vii., plate 61.

PLATE. DV.

Trans. Royal Society, Vol. XXT. P. 255.

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XVII.—On Superposition. By the Rev. Puitie Ketianp, M.A., Professor of
Mathematics in the University of Edinburgh. (With a Plate.)

(Read 19th February 1855.)

The subject which I propose to discuss in this paper is the value of the method
of demonstration by superposition. Iam satisfied that it has been much under-
rated, and in some cases misunderstood. It may be stated, that the essential
characteristic of this method of demonstration, is the mental comparison of two
magnitudes, by placing one of them upon the other. Eucrip’s axiom of equality
(which, perhaps, is rather a definition) is this: ‘“‘ Magnitudes which coincide with
one another, that is, which exactly fill the same space, are equal.” Accordingly,
in his first four books, Euciip never regards two magnitudes as equal, except under
circumstances wherein it can be shown that this condition is satisfied. Only in
one proposition has he avoided the labour which a strict attention to this re-
quirement necessarily imposes; and perhaps, even in that case, it is hypercritical
to object to what he has done. All that he assumes is this: it being admitted
that when A fills the same space as B, A is equal to B; it must therefore be ad-
mitted, that when A and C together fill the same space as B and C together, A
is also equal to B.

In the 6th book, as depending on the 5th, Euctip makes another step in the
assumptions necessary, and, in the 2d proposition, he admits the test of equality
to be this: When two magnitudes can be multiplied equally to any extent, and
when it can be shown, that on every occasion in which one exceeds or falls short
of a magnitude, the other does the same exactly ; then the two cannot fill other
than the same space. .

For the next step in this line of argument, we must advance to NewTon’s
Principia. In the 7th Lemma will be found a beautiful process, by which it is
shown that two inconceivably small magnitudes are, as they get smaller, ap-
proaching to a ratio of equality. The process is simply that of applying a mi-
nute magnifying power, so that one of the things to be compared shall always
be magnified up to a fixed standard.

This is the method of demonstration in geometry. It is not too much to say
that geometry owes nine-tenths of its value, as an educational agent, to its being
a consistent and systematic exemplification of this method. The treatises of
LEGENDRE, in French, and Sir Jonn Lestiz, in English, in which method is set at
defiance, however valuable as introductory to other branches of science, are com-

VOL. XXI. PART II. 4D

272 PROFESSOR KELLAND ON SUPERPOSITION.

paratively useless as elements of training. The loose way in which many of
these treatises are compiled, causes us to be astonished at the celebrity they have
attained. In the treatise of LeEcenpRE, for instance, the author attempts, in his
first edition, to place the doctrine of parallels on a more simple basis,—at that
time, it may be presumed he was tolerably ignorant of the real state of the ques-
tion,—but when his book became pretty generally adopted, he gave his close at-
tention to the subject, and became convinced that his emendation required
amendment. New editions were called for, and new amendments succeeded the
old ones, until, in the tenth edition, we are presented with the following signifi-
cant words as an advertisement: “ By the advice of several distinguished pro-
fessors, I have determined to re-establish, in this tenth edition, the theory of pa-
rallels nearly on the same basis as Eucrip’s.”

The author has thus sailed round nearly all the points of the compass, and
agreeably to his own confession arrives nearly at the poimt at which he started.
Nearly, he says; and, truth to tell, not so very nearly at all. There is certainly
an abandonment of all novelty in the exposition of the doctrine; but any one may
see how very far the author is behind Euciip, even in his tenth edition. If we
could examine the last edition, we should probably find Evuctin’s method com-
pletely restored. At any rate, Lecenpre tells us, in his note, that he is not
satisfied with the theory as it stands, and he attributes its imperfection to the
definition of a straight line; but whether he means his own definition, which is
imperfect enough, no doubt, or Eucuin’s, does not appear.

But it is time we should leave LecenprE, and offer one positive argument in
favour of the method of demonstration by superposition. It is admitted, I think,
that a chain of reasoning upon an abstract definition is the most healthful exer-
cise of the mental powers, at least in the days of youth. Viewed as such, Ev-
cLIpD’s Elements stand above all other writings; but a class of objectors of a totally
different order from LEGENDRE has arisen, who, with considerable show of reason,
urge against geometry, as based on superposition, that it excludes all exercise
of ingenuity, masmuch as it only demands a uniform and unvaried march, to
deviate from which is to wander into error. There is some truth in this,—but it
is not altogether true; and I have here exhibited, in reply to it, some of the dif-
ferent solutions of a single problem where we are bound down by a specific re-
quirement; and it will be seen that the solutions present themselves in tolerable
variety, and that their discovery must have brought out some ingenuity.

The problem was proposed to me by the late lamented Secretary of this So-
ciety, Sir Jonn Ropison. I gave him the first solution. The others have arisen
out of it, partly from my own suggestions, partly from my students’ exercises.
It is certainly a very remarkable problem. I have never met with one which
presents such a variety of altogether independent solutions. ‘There can be no
doubt that the problem has appeared in the Ladies’ Diary, or elsewhere, but I

PROFESSOR KELLAND ON SUPERPOSITION. 273

have never met with it, and I do not suppose, at any rate, that half the solutions
have been dreamt of before. About these solutions I have not many words to
say. It may suffice if I describe the first, and indicate the others by a letter or
two placed in the figures. (See Plate V.)

PRosLeM. From a given square one quarter is cut off, to divide the remaining
gnomon into four such paris that they shall be capable of forming a square.

Let ABE be the gnomon. Let AX bea side of the square which is equal to
this gnomon (Euc., ii, 14): call it 2, and call AB a. In Figure I. draw HK paral-
lel to AB and equal to #~a.

Then (1), (2), and (4) will unite as in Figure II. Also (3) will fit in between
(1), (2), and (4). Now, if the four do not make up a square, either (3) will reach
below P, or (2) will not reach so low as P, or vice versd, seeing that the area is
equal to the square of MP. But neither of these circumstances can happen, be-
cause then HK + GE would be unequal to MR or 2, which it is not. It follows
that the four parts exactly make up a square.

The second method of making the sections differs from the first only in the
different method of producing the portions (2) and (4).

The third differs from the first in the way of producing (2) and (3). This me-
thod may be modified ad libitum. It is only necessary that the portion which (3)
takes from (2) shall be symmetrical with respect to C and K.

The fourth, like the second, is a slight modification of (2) and (4) in the first.
An isosceles triangle is taken out of (4) into (2).

The jifth is a modification of the second. A figure equal to (4) is cut out of
(2) and remains in (3), whilst (4) itself replaces that figure in (2).

The siath is anew form: (38) and (4) instead of being, as in the first method,
cut from the right side, are cut from the left and reversed.

The seventh is again a new form.

The eighth has two pieces in common with the first method. In other respects
it is new.

The ninth is a slight modification of the eighth, the piece (4) being cut from
the top instead of from the bottom.

The tenth is a modification of the seventh.

The eleventh is another modification of the eighth; the piece is now cut out of
the top of (3).

The twelfth is new; and the demonstration is effected by showing that the
figures form a rectangular parallelogram, of which one side is 2.

I must not omit to add, that the major part of these solutions are due to the
ingenuity of my students.

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XVII.— Experiments on Colour, as percewed by the Eye, with remarks on Colour-
Blindness. By James CierK MAxwe tt, B.A., Trinity College, Cambridge.
Communicated by Dr Grecory. (With a Plate.)

(Read 19th March 1855.)

The object of the following communication is to describe a method by which
every variety of visible colour may be exhibited to the eye in such a form as to
admit of accurate comparison; to show how experiments so made may be regis-
tered numerically; and to deduce from these numerical results certain laws of
vision.

The different tints are produced by means of a combination of discs of paper,
painted with the pigments commonly used in the arts, and arranged round an
axis, so that a sector of any required angular magnitude of each colour may be
exposed. When this system of discs is set in rapid rotation, the sectors of the
different colours become indistinguishable, and the whole appears of one uniform
tint. The resultant tints of two different combinations of colours may be com-
pared by using a second set of discs of a smaller size, and placing these over the
centre of the first set, so as to leave the outer portion of the larger discs exposed.
The resultant tint of the first combination will then appear in a ring round that
of the second, and may be very carefully compared with it. -

The form in which the experiment is most manageable is that of the common
top. An axis, of which the lower extremity is conical, carries a circular plate,
which serves as a support for the discs of coloured paper. The circumference of
this plate is divided into 100 equal parts, for the purpose of ascertaining the pro-
portions of the different colours which form the combination. When the discs
have been properly arranged, the upper part of the axis is screwed down, so as to
prevent any alteration in the proportions of the colours.

The instrument used in the first series of experiments (at Cambridge, in No-
vember 1854) was constructed by myself, with coloured papers procured from Mr
D. R. Hay. The experiments made in the present year were with the im-
proved top made by Mr J. M. Bryson, Edinburgh, and coloured papers prepared
by Mr T. Purpre, with the unmixed pigments used in the arts. A number of
Mr Bryson’s tops, with Mr Purpte’s coloured papers has been prepared, so as to
afford different observers the means of testing and comparing results independ-
ently obtained.

VOL. XXI. PART II. AE

276 MR J. CLERK MAXWELL ON COLOUR,

The colours used for Mr Purpie’s papers were—

Vermilion, Q ; V Ultramarine, . : U Emerald Green, : EG
Carmine, : ; C Prussian Blue, : PB Brunswick Green, . BG
Red Lead, : : RL Verditer Blue, : VB Mixture of Ultramarine
Orange Orpiment, . 0O and Chrome, : UC
Orange Chrome, ; OC
Chrome Yellow, ; CY
Gamboge, : ; Gam
Pale Chrome, . : PC

Ivory Black, . : Bk

Snow White, . P SW

White Paper (Pirie, Aberdeen).

The colours in the first column are reds, oranges, and yellows; those in the
second, blues; and those in the third, greens. Vermilion, ultramarine, and
emerald green, seem the best colours to adopt in referring the rest to a uniform
standard. They are therefore put at the head of the list, as types of three con-
venient divisions of colour, red, blue, and green.

It may be asked, why some variety of yellow was not chosen in place of
green, which is commonly placed among the secondary colours, while yellow
ranks as a primary? The reason for this deviation from the received system is,
that the colours on the discs do not represent primary colours at all, but are
simply specimens of different kinds of paint, and the choice of these was deter-
mined solely by the power of forming the requisite variety of combinations. Now,
if red, blue, and yellow, had been adopted, there would have been a difficulty in
forming green by any compound of blue and yellow, while the yellow formed by
vermilion and emerald green is tolerably distinct. This will be more clearly per-
ceived after the experiments have been discussed, by referring to the diagram.

As an example of the method of experimenting, let us endeavour to form a
neutral gray by the combination of vermilion, ultramarine, and emerald green.
The most perfect results are obtained by two persons acting in concert, when the
operator arranges the colours and spins the top, leaving the eye of the observer
free from the distracting effect of the bright colours of the papers when at rest.

After placing discs of these three colours on the circular plate of the top, and
smaller discs of white and black above them, the operator must spin the top, and
demand the opinion of the observer respecting the relation of the outer ring to
the inner circle. He will be told that the outer circle is too red, too blue, or too
green, as the case may be, and that the inner one is too light or too dark, as com-
pared with the outer. The arrangement must then be changed, so as to render
the resultant tint of the outer and inner circles more nearly alike. Sometimes
the observer will see the inner circle tinted with the complementary colour of the
outer one. In this case the operator must interpret the observation with respect
to the outer circle, as the inner circle contains only black and white.

By a little experience the operator will learn how to put his questions, and

AS PERCEIVED BY THE EYE. rae

how to interpret their answers. The observer should not look at the coloured
papers, nor be told the proportions of the colours during the experiments. When
these adjustments have been properly made, the resultant tints of the outer and
inner circles ought to be perfectly indistinguishable, when the top has a sufficient
velocity of rotation. The number of divisions occupied by the different colours
must then be read off on the edge of the plate, and registered in the form of an
equation. Thus, in the preceding experiment we have vermilion, ultramarine,
and emerald green outside, and black and white inside. The numbers, as given

by an experiment on the 6th March 1855, in daylight without sun, are—

37 V+:27 U+ 36 EG=:28 SW+'72 Bk . : : : ; (1).

The method of treating these equations will be given when we come to the theo-
retical view of the subject.

In this way we have formed a neutrgl gray by the combination of the three
standard colours. We may also form neutral grays of different intensities by the
combination of vermilion and ultramarine with the other greens, and thus obtain
the quantities of each necessary to neutralize a given quantity of the proposed
green. By substituting for each standard colour in succession one of the colours
which stand under it, we may obtain equations, each of which contains two stand-
ard colours, and one of the remaining colours.

Thus, in the case of pale chrome, we have, from the same set of experiments,

°34 PC +°55 U+:12 EG=:37 SW +:63 Bk : : : : (2).

We may also make experiments in which the resulting tint is not a neutral
gray, but adecided colour. Thus we may combine ultramarine, pale chrome, and
black, so as to produce a tint identical with that of a compound of vermilion and
emerald green. Experiments of this sort are more difficult, both from the inabi-
lity of the observer to express the difference which he detects in two tints which
have, perhaps, the same hue and intensity, but differ in purity; and also from
the complementary colours which are produced in the eye after gazing too long at
the colours to be compared.

The best method of arriving at a result in the case before us, is to render the
hue of the red and green combination something like that of the yellow, to reduce
the purity of the yellow by the admixture of blue, and to diminish its zntensity by
the addition of black. These operations must be repeated and adjusted, till the
two tints are not merely varieties of the same colour, but absolutely the same.
An experiment made 5th March gives—

SO ROe Ohl 40, Bic = Oe AGH Wd coal me Job (8).

That these experiments are really evidence relating to the constitution of the eye,
and not mere comparisons of two things which are in themselves identical, may
be shown by observing these resultant tints through coloured glasses, or by using

278 MR J. CLERK MAXWELL ON COLOUR,

gas-light instead of day-light. The tints which before appeared identical will now
be manifestly different, and will require alteration, to reduce them to equality.
Thus, in the case of carmine, we have by day-light,

‘44 C+°:22 U+'34 EG=17 SW +°83 Bk
while by gas-light (Edinburgh)
‘47 C+:08 U+-45 EG=:25 SW +°75 Bk

which shows that the yellowing effect of the gas-light tells more on the white
than on the combination of colours. If we examine the two resulting tints which
appeared identical in experiment (3), observing the whirling discs through a
blue glass, the combination of yellow, blue, and black, appears redder than the
other, while through a yellow glass, the red and green mixture appears redder.
So also a red glass makes the first side of the equation too dark, and a green
glass makes it too light.

The apparent identity of the tints in these experiments is therefore not real,
but a consequence of a determinate constitution of the eye, and hence arises the
importance of the results, as indicating the laws of human vision.

The first result which is worthy of notice is, that the equations, as observed
by different persons of ordinary vision, agree in a remarkable manner. If care
be taken to secure the same kind of light in all the experiments, the equations,
as determined by two independent observers, will seldom show a difference of
more than three divisions in any part of the equation containing the bright stand-
ard colours. As the duller colours are less active in changing the resultant tint,
their true proportions cannot be so well ascertained. The accuracy of vision of
each observer may be tested by repeating the same experiment at different times,
and comparing the equations so found.

Experiments of this kind, made at Cambridge in November 1854, show that
of ten observers, the best were accurate to within 13 division, and agreed within
1 division of the mean of all; and the worst contradicted themselves to the ex-
tent of 6 degrees, but still were never more than 4 or 5 from the mean of all
the observations.

Weare thus led to conclude—

1st, That the human eye is capable of estimating the likeness of colours with
a precision which in some cases is very great.

2d, That the judgment thus formed is determined, not by the real identity of
the colours, but by a cause residing in the eye of the observer.

3d, That the eyes of different observers vary in accuracy, but agree with each
other so nearly as to leave no doubt that the law of colour-vision is identical for
all ordinary eyes.

AS PERCEIVED BY THE EYE. 279

Investigation of the Law of the Perception of Colour.

Before proceeding to the deduction of the elementary laws of the perception of
colour from the numerical results previously obtained, it will be desirable to point
out some general features of the experiments which indicate the form which these
laws must assume.

Returning to experiment (1), in which a neutral gray was produced from red,
blue, and green, we may observe, that, while the adjustments were incomplete, the
difference of the tints could be detected only by one circle appearing more red,
more green, or more blue than the other, or by being lighter or darker, that is, hav-
ing an excess or defect of all the three colours together. Hence it appears that
the nature of a colour may be considered as dependent on three things, as, for in-
stance, redness, blueness, and greenness. This is confirmed by the fact, that any
tint may be imitated by mixing red, blue, and green alone, provided that tint does
not exceed a certain brilliancy.

Another way of showing that colour depends on three things is, by consider-
ing how two tints, say two lilacs, may differ. In the first place, one may be
lighter or darker than the other, that is, the tints may differ in shade. Secondly,
one may be more Jlue or more red than the other, that is, they may differ in hwe.
Thirdly, one may be more or less deczded in its colour; it may vary from purity on
the one hand, to neutrality on the other. This is sometimes expressed by saying
that they may differ in zint.

Thus, in shade, hue, and tint, we have another mode of reducing the elements
of colour to three. It will be shown that these two methods of considering colour
may be deduced one from the other, and are capable of exact numerical com-
parison.

On a Graphical Method of Exhibiting the Relations of Colours.

The method which exhibits to the eye most clearly the results of this theory
of the three elements of colour, is that which supposes each colour to be repre-
sented by a point in space, whose distances from three co-ordinate planes are
proportional to the three elements of colour. Butas any method by which the ope-
rations are confined to a plane is preferable to one requiring space of three di-
mensions, we shall only consider for the present that which has been adopted for
convenience, founded on Nrewrton’s Circle of Colours and Mayer and Youna’s
Triangle.

Vermilion, ultramarine, and emerald green, being taken (for convenience) as
standard colours, are conceived to be represented by three points, taken (for con-
venience) at the angles of an equilateral triangle. Any colour compounded of
these three is to be represented by a point found by conceiving masses propor-

VOL. XXI. PART I. 4F

280 MR J. CLERK MAXWELL ON COLOUR,

tional to the several components of the colour placed at their respective angular
points, and taking the centre of gravity of the three masses. In this way, each
colour will indicate by its position the proportions of the elements of which it is
composed. The total intensity of the colour is to be measured by the whole
number of divisions of V, U, and EG, of which it is composed. This may be
indicated by a number or coefficient appended to the name of the colour, by
which the number of divisions it occupies must be multiplied to obtain its mass
in calculating the results of new combinations.

This will be best explained by an example on the diagram (No. 1). We have,
by experiment (1),

87 V +:27 U +36 EG=:28SW+-72 Bk

To find the position of the resultant neutral tint, we must conceive a mass
of -37 at V, of -27 at U, and of ‘36 at EG, and find the centre of gravity. This
may be done by taking the line UV, and dividing it in the proportion of ‘37 to 27
at the point a, where

a@ Nes @ Ure 27 sor

Then, joining a with EG, divide the joining line in W in the proportion of ‘36 to
(37 4°27), W will be the position of the neutral tint required, which is not white,
but 0:28 of white, diluted with 0°72 of black, which has hardly any effect what-
ever, except in decreasing the amount of the other colour. The total intensity of
our white paper will be represented by sg =3'57 ; so that, whenever white enters
into an equation, the number of divisions must be multiplied by the coefficient
3°57 before any true results can be obtained.

We may take, as the next example, the method of representing the relation
of pale chrome to the standard colours on our diagram, by making use of experi-
ment (2), in which pale chrome, ultramarine, and emerald green, produced a neu-
tral gray. The resulting equation was

33 PC +55 U+':12 EG=:37 SW+°63 Bk. ; ' oh 4 koe

In order to obtain the total intensity of white, we must multiply the number
of divisions, 37, by the proper coefficient, which is 3°57. The result is 1°32, which
therefore measures the total intensity on both sides of the equation.

Subtracting the intensity of 55 U +-:12 EG, or ‘67 from 1:32, we obtain °65 as
the corrected value of 32 PC. It will be convenient to use these corrected values
of the different colours, taking care to distinguish them by small initials instead
of capitals.

Equation (2) then becomes

65 pe+°55 U+°12 EG=1:32 w

AS PERCEIVED BY THE EYE. 281

Hence pc must be situated at a point such that w is the centre of gravity of
‘65 pc+ 55 U+-12 EG.

To find it, we begin by determining @ the centre of gravity of 55 U+ +12 EG,
then, joining @ w, the point we are seeking must lie at a certain distance on the
other side of w from c. This distance may be found from the proportion,

65: (554°12):: @w:wpe
which determines the position of pe. The proper coefficient, by which the ob-
served values of PC must be corrected is &, or 1:97.

We have thus determined the position and coefficient of a colour by a single
experiment, in which it was made to produce a neutral tint along with two of
the standard colours. As this may be done with every possible colour, the
method is applicable wherever we can obtain a disc of the proposed colour. In
this way the diagram (No. 1) has been laid down from observations made in day-
light, by a good eye of the ordinary type.

It has been observed that experiments, in which the resultant tint is neutral,
are more accurate than those in which the resulting tint has a decided colour, as
in experiment (3), owing to the effects of accidental colours produced in the eye
in the latter case. These experiments, however, may be repeated till a very
good mean result has been obtained.

But since the elements of every colour have been already fixed by our pre-
vious observations and calculations, the agreement of these results with those
calculated from the diagram forms a test of the correctness of our method.

By experiment (No. 3), made at the same time with (1) and (2), we have

39 PC+-21 U+:40 Bk=-59 V+-41 EG Ra Eee:
Now, joing U with pe, and V with EG, the only common point is that at
which they cross, namely ¥.
Measuring the parts of the line V EG, we find them in the proportion of
‘58 V and -42 EG=1-00
Similarly, the line U pc is divided in the proportion
‘78 pe and :22 U=1:00 y
But ‘78 pc must be divided by 1:97, to reduce it to PC, as was previously ex-
plained. The result of calculation is, therefore,

39 PC +:22 U+:39 Bk=:58 V +:42 EG

the black being introduced simply to fill up the circle.

This result differs very little from that of experiment (3), and it must be re-
collected that these are single experiments,made independently of theory, and
chosen at random.

282 MR J. CLERK MAXWELL ON COLOUR,

Experiments made at Cambridge, with all the combinations of five colours,
show that theory agrees with calculation always within 0°012 of the whole, and
sometimes within 0-002. By the repetition of these experiments at the numerous
opportunities which present themselves, the accuracy of the results may be ren-
dered still greater. As it is, 1am not aware that the judgments of the human
eye with respect to colour have been supposed capable of so severe a test.

Further consideration of the Diagram of Colours.

We have seen how the composition of any tint, in terms of our three standard
colours, determines its position on the diagram and its proper coefficient. In the
same way, the result of mixing any other colours, situated at other points of the
diagram, is to be found by taking the centre of gravity of their reduced masses, as
was done in the last calculation (experiment 3).

We have now to turn our attention to the general aspect of the diagram.

The standard colours, V, U, and EG, occupy the angles of an equilateral tri-
angle, and the rest are arranged in the order in which they participate in red,
blue, and green, the neutral tint being at the point w within the triangle. If we
now draw lines through w to the different colours ranged round it, we shall find
that, if we pass from one line to another in the order in which they lie from red
to green, and through blue back again to red, the order will be—

Coefficient. Coefficient.
Carmine, . ; 4 : 0-4 Pale Chrome . ! : 2°0
Vermilion, 1:0 Mixed Green (UC), . d 0-4
Red Lead, é : 1:3 Brunswick Green, : 0:2
Orange Orpiment, , 1:0 Emerald Green, : : 1-0
Orange Chrome, 16 Verditer Blue, . ; : 0-8
Chrome Yellow, 1°5 Prussian Blue, . : ; O-1
Gamboge, 1:8 Ultramarine, . : 4 1:0

It may be easily seen that this arrangement of the colours corresponds to that
of the prismatic spectrum; the only difference being that the spectrum is deficient
in those fine purples which lie between ultramarine and vermilion, and which
are easily produced by mixture. The experiments necessary for determining
the exact relation of this list to the lines in the spectrum are not yet completed.

If we examine the colours represented by different points in one of these lines
through w, we shall find the purest and most decided colours at its outer ex-
tremity, and the faint tints approaching to neutrality nearer to .

If we also study the coefficients attached to each colour, we shall find that
the brighter and more luminous colours have higher numbers for their coefficients
than those which are dark.

_In this way, the qualities which we have already distinguished as hue, tint,
aud shade, are represented on the diagram by angular position with respect to 2,
distance from w, and coefficient; and the relation between the two methods of
reducing the elements of colour to three becomes a matter of geometry.

AS PERCEIVED BY THE EYE. 283

Theory of the Perception of Colour.

Opticians have long been divided on this point; those who trusted to popular
notions and their own impressions adopting some theory of three primary colours,
while those who studied the phenomena of light itself proved that no such
theory could explain the constitution of the spectrum. Nrwrton, who was the
first to demonstrate the actual existence of a series of kinds of light, countless in
number, yet all perfectly distinct, was also the first to propound a method of cal-
culating the effect of the mixture of various coloured light; and this method was
substantially the same as that which we have just verified. It is true, that the
directions which he gives for the construction of his circle of colours are somewhat
arbitrary, being probably only intended as an indication of the general nature of
the method, but the method itself is mathematically reducible to the theory of
three elements of the colour-sensation. *

Youne, who made the next great step in the establishment of the theory of
light, seems also to have been the first to follow out the necessary consequences
of NewTon’s suggestion on the mixture of colours. He saw that, since this tri-
plicity has no foundation in the theory of light, its cause must be looked for in
the constitution of the eye ; and, by one of those bold assumptions which some-
times express the result of speculation better than any cautious trains of reason-
ing, he attributed it to the existence of three distinct modes of sensation in the
retina, each of which he supposed to be produced in different degrees by the dif-
ferent rays. These three elementary effects, according to his view, correspond to
the three sensations of red, green, and violet, and would separately convey to the
sensorium the sensation of a red, a green, and a violet picture; so that by the su-
perposition of these pictures, the actual variegated world is represented.t+

In order fully to understand Youna’s theory, the function which he attributes
to each system of nerves must be carefully borne in mind. Each nerve acts, not,
as some have thought, by conveying to the mind the knowledge of the length of
an undulation of light, or of its periodic time, but simply by being more or less
affected by the rays which fall on it. The sensation of each elementary nerve is
capable only of increase and diminution, and of no other change. We must also
observe, that the nerves corresponding to the red sensation are affected chiefly by
the red rays, but in some degree also by those of every other part of the spectrum ;
just as red glass transmits red rays freely, but also suffers those of other colours
to pass in smaller quantity.

This theory of colour may be illustrated by a supposed case taken from

* See Note III. For a confirmation of Newrton’s analysis of Light, see Heztmuoirz. Poae.
Ann. 1852; and Phil. Mag. 1852, Part IT.

{+ Youne’s Lectures, p. 8345, Keriann’s Edition. See also Hetmuonrz’s statement of Youne’s
Theory, in his Paper referred to in Note I.; and Herscuex’s Light, Art. 518.

VOH. XXL PART I, 4G

284 MR J. CLERK MAXWELL ON COLOUR,

the art of photography. Let it be required to ascertain the colours of a land-
scape, by means of impressions taken on a preparation equally sensitive to rays
of every colour.

Let a plate of red glass be placed before the camera, and an impression taken.
The positive of this will be transparent wherever the red light has been abundant
in the landscape, and opaque where it has been wanting. Let it now be put in
a magic lantern, along with the red glass, and ared picture will be thrown on
the screen.

Let this operation be repeated with a green and a violet glass, and, by means
of three magic lanterns, let the three images be superimposed on the screen. The
colour of any point on the screen will then depend on that of the corresponding
point of the landscape ; and, by properly adjusting the intensities of the lights,
&c., a complete copy of the landscape, as far as visible colour is concerned, will
be thrown on the screen. The only apparent difference will be, that the copy
will be more subdued, or less pure in tint, than the original. Here, however, we
have the process performed twice—first on the screen, and then on the retina.

This illustration will show how the functions which Youne attributes to the
three systems of nerves may be imitated by optical apparatus. It is therefore
unnecessary to search for any direct connection between the lengths of the undu-
lations of the various rays of light and the sensations as felt by us, as the three-
fold partition of the properties of light may be effected by physical means. The
remarkable correspondence between the results of experiments on different indi-
viduals would indicate some anatomical contrivance identical in all. As there is
little hope of detecting it by dissection, we may be content at present with any
subsidiary evidence which we may possess. Such evidence is furnished by those
individuals who have the defect of vision which was described by Datron, and
which is a variety of that which Dr G. Wirson has lately investigated, under the
name of Colour-Blindness.

Testimony of the Colour-blind with respect to Colour.

Dr Grorce Witson has described a great number of cases of colour-blindness,
some of which involve a general indistinctness in the appreciation of colour,
while in others, the errors of judgment are plainly more numerous in those
colours which approach to red and green, than among those which approach to
blue and yellow. In these more definite cases of colour-blindness, the phenome-
na can be tolerably well accounted for by the hypothesis of an insensibility to
red light; and this is, to a certain extent, confirmed by the fact, that red objects
appear to these eyes decidedly more obscure than to ordinary eyes. But by ex-
periments made with the pure spectrum, it appears that though the red appears
much more obscure than other colours, it is not wholly invisible, and, what is more
curious, resembles the green more than any other colour. The spectrum to them

AS PERCEIVED BY THE EYE. 285

appears faintly luminous in the red; bright yellow from orange to yellow, bright
but not coloured from yellow-green to blue, and then strongly coloured in the
extreme blue and violet, after which it seems to approach the neutral obscure
tint of the red. It is not easy to see why an insensibility to red 7 ays should de-
prive the green rays, which have no optical connection with them, of their dis-
tinctive appearance. The phenomena seem rather to lead to the conclusion that
it is the red sensation which is wanting, that is, that supposed system of nerves
which is affected in various degrees by all light, but chiefly by red. We have
fortunately the means of testing this hypothesis by numerical results.

Of the subjects of my experiments at Cambridge, four were decided cases of
colour-blindness. Of these two, namely, Mr R. and Mr S., were not sufficiently
critical in their observations to afford any results consistent within 10 divisions of
the colour-top. The remaining two, Mr N. and Mr X., were as consistent in their
observations as any persons of ordinary vision can be, while the results showed
all the more clearly how completely their sensations must differ from ours.

The method of experimenting was the same as that adopted with ordinary
eyes, except that in these cases the operator can hardly influence the result by
yielding to his own impressions, as he has no perception whatever of the simi-
larity of the two tints as seen by the observer. The questions which he must
ask are two, Which circle appears most blue or yellow? Which appears lightest
and which darkest? By means of the answers to these questions he must adjust
the resulting tints to equality in these respects as it appears to the observer, and
then ascertain that these tints now present no difference of colour whatever to
his eyes. The equations thus obtained do not require five colours including
black, but four only. For instance, the mean of several observations gives—

19 G+-05 B+-76 Bk=100 R Les hag ang ane 2)

[In these experiments R, B, G, Y, stand for red, blue, green, and yellow papers
prepared by Mr D. R. Hay. Iam not certain that they are identical with his

‘standard colours, but I believe so. Their relation to vermilion, ultramarine, and

emerald-green is given in diagram (1). Their relations to each other are very
accurately given in diagram (2). |

It appears, then, that the dark blue-green of the left side of the equation is
equivalent to the full red of the right side.

Hence, if we divide the line BG in the proportion of 19 to 5 at the point 8,
and join R £, the tint at 8 will differ from that at R (to the colour-blind) only in
being more brilliant in the proportion of 100 to 24, and all intermediate tints on
the line R @ will appear to them of the same hue, but of intermediate intensities.

Now, if we take a point D, so that RD is to R@ in the proportion of 24 to
100-24, or 76, the tint of D, if producible, should be invisible to the colour-blind.
D, therefore, represents the pure sensation which is unknown to the colour-blind,

286 MR J. CLERK MAXWELL ON COLOUR,

and the addition of this sensation to any others cannot alter it in their estima-
tion. It is for them equivalent to black.

Hence, if we draw lines through D in different directions, the colours belong-
ing to the line ought to differ only in intensity as seen by them, so that one of
them may be reduced to the other by the addition of black only. If we draw DW
and produce it, all colours on the ypper side of DW will be varieties of blue, and
those on the under side varieties of yellow, so that the line DW is a boundary
line between their two kinds of colour, blue and yellow being the names by which
they call them. ‘

The accuracy of this theory will be evident from the comparison of the expe-
riments which I had an opportunity of making on Mr N. and Mr X. with each
other, and with measurements taken from the diagram No. 2, which was con-
structed from the observations of ordinary eyes only, the point D alone being
ascertained from a series of observations by Mr N.

Taking the point Y, between R and B, it appears, by measurement of the lines
R yand BY, that Y corresponds to

07 B+ 93 R
By measurement of W Y and D7, and correction by means of the coefficient of
W, and calling D black in the colour-blind language, Y corresponds to

105 W + -895 Bk

Therefore,
By measurement, , i -°93 R+:07 B=:105 W +-895 Bk
By observation N. & X. together, ‘94 R+:06 B= 10 W+ ‘90 Bk (5).
By X-along, ls, SORE OLB AO W U0 be

The agreement here is as near as can be expected.
By a similar calculation with respect to the point 6, between B and G,

By measurement, . 43 B+°57 G=-335 W+-665 Bk
Observed by N. and X., -41 B+°59 G= -34 W+ -66 Bk (6).
By X. alone, . - ‘42 B+°58 G= -32 W+ ‘68 Bk

We may also observe, that the line GD crosses RY. At the point of inter-
section we have—
By calculation, . - 87 R+-13 Y=:34 G+°66 Bk |
Observed by N. and X., ‘86 R+-14 Y=-40 G+-60 Bk ey wity At
eee X., 84 R+-16 Y=:31 G+-69 Bk |
X, 90 R+-10 Y=-27 G+-73 Bk J

Here observations are at variance, owing to the decided colours produced af-
fecting the state of the retina, but the mean agrees well with calculation.
Drawing the line BY, we find that it cuts lines through D drawn to every

AS PERCEIVED BY THE EYE. 287

colour. Hence all colours appear to the colour-blind as if composed of blue and
yellow. By measurement on the diagram, we find for red

Measured, . é 138 Y +-123 B+-749 Bk=100 R
Observed by N.,_ . 15 Y+ 11B+ ‘74 Bk=100R (8).
eee eats 13 Y+ ‘11 B+ :76 Bk=100 R
’ For green we have in the same way—
Measured, : ‘705 Y +295 B=:95 G+:05 Bk
Observed by N., ‘ ‘70 Y+ :30 B=:86 G+-14 Bk (9).
ove X., ; ‘70 Y+ °30 B=:83 G+°17 Bk
For white—
Measured, ‘407 Y+°593 B=-326 W +674 Bk
Observed by N., ‘40 Y+ :60 B= 33 W+ ‘67 Bk
bk x 44 Y+ -56 B= -:33 W+ ‘67 Bk

The accuracy of these results shows that, whether the hypothesis of the want
of one element out of three necessary to perfect vision be actually true or not, it
affords a most trustworthy foundation on which to build a theory of colour-
blindness, as it expresses completely the observed facts of the case. They also
furnish us with a datum for our theory of perfect vision, namely, the point D,
which points out the exact nature of the colour-sensation, which must be added
to the colour-blind eye to render it perfect. I am not aware of any method of
determining by a legitimate process the nature of the other two sensations, al-
though Youne’s reasons for adopting something like green and violet appear to
me worthy of attention.

The only remaining subject to which I would call the attention of the Society
is the effect of coloured glasses on the colour-blind. Although they cannot dis-
tinguish reds and greens from varieties of gray, the transparency of red and green
glasses for those kinds of light is very different. Hence, after finding a case such
as that in equation (4), in which a red and a green appear identical, on looking
through a red glass they see the red clearly and the green obscurely, while through
a green glass the red appears dark and the green light.

By furnishing Mr X. with a red and a green glass, which he could distinguish
only by their shape, I enabled him to make judgments in previously doubtful
cases of colour with perfect certainty. I have since had a pair of spectacles con-
structed with one eye-glass red and the other green. These Mr X. intends to use
for a length of time, and he hopes to acquire the habit of discriminating red from
green tints by their different effects on his two eyes. Though he can never ac-
quire our sensation of red, he may then discern for himself what things are red,
and the mental process may become so familiar to him as to act unconsciously
like a new sense.

VOL. XXI. PART II. 4H

288 MR J. CLERK MAXWELL ON COLOUR,

In one experiment, after looking at a bright light, with a red glass over one
eye and a green over the other, the two tints in experiment (4) appeared to him
altered, so that the outer circle was lighter according to one eye, and the inner
according to the other. As far as I could ascertain, it appeared as if the eye
which had used the red glass saw the red circle brightest. This result, which
seems at variance with what might be expected, I have had no opportunity of
verifying.

This paper is already longer than was originally intended. For further infor-
mation I would refer the reader to NEwton’s Opticks, Book I. Part II., to Youna’s
Lectures on Natural Philosophy, page 345, to Mr D. R. Hay’s works on Colours,
and to Professor Forses on the Classification of Colours (Phil. Mag., March 1849).

The most remarkable paper on the subject is that of M. HELMHOLTz, in the
Philosophical Magazine for 1852, in which he discusses the different theories of
primary colours, and describes his method of mixing the colours of the spectrum.
An examination of the results of M. HetMuonrz with reference to the theory
of three elements of colour, by Professor GRAssMANN, is translated in the Phil.
Mag., April 1854.

References to authors on colour-blindness are given in Dr G. WiLson’s papers
on that subject. A valuable Letter of Sir J. F. W. Herscuer to Darron on his
peculiarity of vision, is to be found in the Life of Daron by Dr Henry.

I had intended to describe some experiments on the propriety of the method
of mixing colours by rotation, which might serve as an extension of Mr Swan’s
experiments on instantaneous impressions on the eye. These, together with the
explanation of some phenomena which seem to be at variance with the theory of
vision here adopted, must be deferred for the present. On some future occasion,
I hope to be able to connect these simple experiments on the colours of pigments
with others in which the pure hues of the spectrum are used. I have already
constructed a model of apparatus for this purpose, and the results obtained are
sufficiently remarkable to encourage perseverance.

Nore I.
On different Methods of Exhibiting the Mixtures of Colours.

(1.) Mechanical Miature of Coloured Powders.

By grinding coloured powders together, the differently-coloured particles may
be so intermingled that the eye cannot distinguish the colours of the separate
powders, but receives the impression of a uniform tint, depending on the nature
and proportions of the pigments used. In this way, NEwTon mixed the powders
of orpiment, purple, bise, and viride wris, so as to form a gray, which, in sunlight,
resembled white paper in the shade. (NEwron’s Opticks, Book I. Part IL. Exp.

AS PERCEIVED BY THE EYE. 289

XV.) This method of mixture, besides being adopted by all painters, has been
employed by optical writers as a means of obtaining numerical results. The spe-
cimens of such mixtures given by D. R. Hay in his works on Colour, and the ex-
periments of Professor J. D. Fores on the same subject, show the importance of
the method as a means of classifying colours. There are two objections, however,
to this method of exhibiting colours to the eye. When two powders of unequal

fineness are mixed, the particles of the finer powder cover over those of the

coarser, so as to produce more than their due effect in influencing the resultant

tint. For instance, a small quantity of lamp-black, mixed with a large quantity

of chalk, will produce a mixture which is nearly black. Although the powders
generally used are not so different in this respect as lamp-black and chalk, the
results of mixing given weights of any coloured powders must be greatly modified
by the mode in which these powders have been prepared.

Again, the light which reaches the eye from the surface of the mixed powders
consists partly of light which has fallen on one of the substances mixed without
being modified by the other, and partly of light which, by repeated reflection or
transmission has been acted on by both substances. The colour of these rays will
not be a mixture of those of the substances, but will be the result of the absorp-
tion due to both substances successively. Thus, a mixture of yellow and blue
produces a neutral tint tending towards red, but the remainder of white light,
after passing through both, is green; and this green is generally sufficiently
powerful to overpower the reddish gray due to the separate colours of the sub-
stances mixed. This curious result has been ably investigated by Professor
Hetmuottz of Konigsberg, in his Memoir on the Theory of Compound Colours, a
translation of which may be found in the Annals of Philosophy for 1852, Part 2.

(2.) Mixture of diferently-coloured Beams of Light by Superposition on an Opaque Screen.

When we can obtain light of sufficient intensity, this method produces the
most beautiful results. The best series of experiments of this kind are to be
found in Newron’s Opticks, Book I. Part II. The different arrangements for
mixing the rays of the spectrum ona screen, as described by NewTon, form a very
complete system of combinations of lenses and prisms, by which almost every
possible modification of coloured light may be produced. The principal objec-
tions to the use of this method are—(1.) The difficulty of obtaining a constant
supply of uniformly intense light; (2.) The uncertainty of the effect of the posi-
tion of the screen with respect to the incident beams and the eye of the observer ;
(3.) The possible change in the colour of the incident light due to the jlworescence
of the substance of the screen. Professor Stokes has found that many substances,
when illuminated by homogeneous light of one refrangibility, become themselves
luminous, so as to emit light of lower refrangibility. This phenomenon must be
carefully attended to when screens are used to exhibit light.

290 MR J. CLERK MAXWELL ON COLOUR,

(3.) Union of Coloured Beams by a Prism so as to form one Beam.

The mode of viewing the beam of light directly, without first throwing it on
a screen, wasnot much used by the older experimenters, but it possesses the ad-
vantage of saving much light, and admits of examining the rays before they have
been stopped in any way. In Newron’s 11th proposition of the 2d Book, an experi-
ment is described, in which a beam is analysed by a prism, concentrated by a
lens, and recombined by another prism, so as to form a beam of white light simi-
lar to the incident beam. By stopping the coloured rays at the lens, any pro-
posed combination may be made to pass into the emergent beam, where it may be
received directly by the eye, or on a screen, at pleasure.

The experiments of HeLmHoLTz on the colours of the spectrum were made
with the ordinary apparatus for directly viewing the pure spectrum, two oblique
slits crossing one another being employed to admit the light instead of one vertical
slit. Two pure spectra were then seen crossing each other, and so exhibiting at
once a large number of combinations. The proportions of these combinations
were altered by varying the inclination of the slits to the plane of refraction, and
in this way a number of very remarkable results were obtained,—for which see
his Memoir, before referred to. one

In experiments of the same kind made by myself in August 1852 (indepen-
dently of M. Hetmuottz), I used a combination of three moveable vertical slits to
admit the light, instead of two cross slits, and observed the compound ray through
a slit made in a screen on which the pure spectrum is formed. In this way a
considerable field of view was filled with the mixed light, and might be compared
with another part of the field illuminated by light proceeding from a second sys-
tem of slits, placed below the first set. The general character of the results agreed
with those of M. Hetmuottz. ‘The chief difficulties seemed to arise from the de-
fects of the opticala pparatus of my own eye, which rendered apparent the
compound nature of the light, by analysing it asa prism or an ordinary lens
would do, whenever the lights mixed differed much in refrangibility.

(4.) Union of two beams by means of a tra .sparent surface, which reflects the first and
transmits the second.

The simplest experiment of this kind is described by M. Hetmuotrz. He
places two coloured wafers on a table, and then, taking a piece of transparent
glass, he places it between them, so that the reflected image of one apparently
coincides with the other as seen through the glass. The colours are thus mixed,
and, by varying the angle of reflection, the relative intensities of the reflected and
transmitted beams may be varied at pleasure.

In an instrument constructed by myself for photometrical purposes two re-
fiecting plates were used. They were placed in a square tube, so as to polarize

AS PERCEIVED BY THE EYE. 291

the incident light, which entered through holes in the sides of the tubes, and was
reflected in the direction of the axis. In this way two beams oppositely polarized
were mixed, either of which could be coloured in any way by coloured glasses
placed over the holes in the tube. By means of a Nicou’s prism placed at the
end of the tube, the relative intensities of the two colours as they entered the eye
could be altered at pleasure.

(5.) Union of two coloured beams by means of a doubly-refracting Prism.

I am not aware that this method has been tried, although the opposite polari-
zation of the emergent rays is favourable to the variation of the experiment.

(6.) Successive presentation of the diferent Colours to the Retina.

It has long been known, that light does not produce its full effect on the eye
at once, and that the effect, when produced, remains visible for some after the light
has ceased to act. In the case of the rotating disc, the various colours become
indistinguishable, and the disc appears of a uniform tint, which is in some sense
the resultant of the colours so blended. This method of combining colours has
been used since the time of Newton, to exhibit the results of theory. The expe-
riments of Professor J. D. Forses, which I witnessed in 1849, first encouraged me
to think that the laws of this kind of mixture might be discovered by special ex-
periments. After repeating the well-known experiment in which a series of colours
representing those of the spectrum are combined to form gray, Professor Forsrs
endeavoured to form a neutral tint, by the combination of three colours only. For
this purpose, he combined the three so-called primary colours, red, blue, and
yellow, but the resulting tint could not be rendered neutral by any combination
of these colours; and the reason was found to be, that blue and yellow do not
make green, but a pinkish tint, when neither prevails in the combination. It was
plain, that no addition of ved to this, could produce a neutral tint.

This result of mixing blue and yellow was, I believe, not previously known. It
directly contradicted the received theory of colours, and seemed to be at variance
with the fact, that the same blue and yellow paint, when ground together, do
make green. Several experiments were proposed by Professor Forses, in order
to eliminate the effect of motion, but he was not then able to undertake them.
One of these consisted in viewing alternate stripes of blue and yellow, with a
telescope out of focus. I have tried this, and find the resultant tint pink as be-
fore.* JI also found that the beams of light coloured by transmission through
blue and yellow glasses appeared pink, when mixed on a screen, while a beam of
light, after passing through both glasses, appeared green. By the help of the
theory of absorption, given by Herscue,} I made out the complete explanation

* See however Encyc. Metropolitana, Art. “ Light,” section 502. t Ib. sect. 516.
VOL. XXI. PART II. 41

292 MR J. CLERK MAXWELL ON COLOUR,

of this phenomenon. Those of pigments were, I think, first explained by Hetm-
HOLTZ in the manner above referred to.*

It may still be asked, whether the effect of successive presentation to the eye is
identical with that of simultaneous presentation, for if there is any action of the
one kind of light on the other, it can take place only in the case of simultaneous
presentation. An experiment tending to settle this point is recorded by Newron
(Book I. Part Il, Exp. 10). He used a comb with large teeth to intercept various
rays of the spectrum. When it was moved slowly, the various colours could be
perceived, but when the speed was increased the result was perfect whiteness.
For another form of this experiment, see Newron’s Sixth Letter to OLDENBURG
(HorsLeEy’s Edition, vol. iv., page 335.)

In order more fully to satisfy myself on this subject, I took a disc in which
were cut a number of slits, so as to divide it into spokes. In a plane, nearly
passing through the axis of this disc, I placed a blue glass, so that one half of the
disc might be seen by transmitted light—blue, and the other by reflected light—
white. Inthe course of the reflected light I placed a yellow glass, and in this
way I had two nearly coincident images of the slits, one yellow and one blue.
By turning the disc slowly, I observed that in some parts the yellow slits and
the blue slits appeared to pass over the field alternately, while in others they
appeared superimposed, so as to produce alternately their mixture, which was
pale pink, and complete darkness. As long as the disc moved slowly I could
perceive this, but when the speed became great, the whole field appeared uni-
formly coloured pink, so that those parts in which the colours were seen succes-
sively were indistinguishable from those in which they were presented together
to the eye.

Another fcrm in which the experiment may be tried requires only the colour-
top above described. ‘The disc should be covered with alternate sectors of any
two colours, say red and green, disposed alternately in four quadrants. By
placing a piece of glass above the top, in the plane of the axis, we make the image
of one half seen by reflection coincide with that of the other seen by transmission.
It will then be seen that, in the diameters of the top which are parallel and per-
pendicular to the plane of reflection, the transmitted green coincides with the
reflected green, and the transmitted red with the reflected red, so that the result
is always either pure red or pure green. But in the diameters intermediate to
these, the transmitted red coincides with the reflected green, and vice versa, so that
the pure colours are never seen, but only their mixtures. As long as the top is
spun slowly, these parts of the disc will appear more steady in colour than those
in which the greatest alternations take place; but when the speed is sufficiently

* T have lately seen a passage in Moreno’s Cosmos, stating that M. Prarteav, in 1819, had ob-
tained gray by whirling together gamboge and Prussian blue.—Correspondence Math. et Phys., de
M. QuETELET, vol. v., p. 221.

.

AS PERCEIVED BY THE EYE. 293

increased, the disc appears perfectly uniform in colour. From these experiments
it appears, that the apparent mixture of colours is not due to a mechanical super-
position of vibrations, or to any mutual action of the mixed rays, but to some
cause residing in the constitution of the apparatus of vision.

(7.) Presentation of the Colours to be mixed one to each Eye.

This method is said not to succeed with some people; but I have always
found that the mixture of colours was perfect, although it was difficult to con-
ceive the objects seen by the two eyes as identical. In using the spectacles, of |
which one eye is green and the other red, I have found, when looking at an ar-
rangement of green and red papers, that some looked metallic and others trans-
parent. This arises from the very different relations of brightness of the two
colours as seen by each eye through the spectacles, which suggests the false con-
clusion, that these differences are the result of reflection from a polished surface,
or of light transmitted through a clear one.

Notes I.
Results of Experiments with Mr Hay’s Papers, at Cambridge, November 1854.

The mean of ten observations made by six observers gave—
‘449 R+-299 G4+-252 B=:224 W+°:776 Bk . , : a LESSIG
696 R+:304 G=:181 B+°327 Y +:492 Bk ‘ } : SCD):

These two equations served to determine the positions of white and yellow in
diagram No. 2. The coefficient of W is 4:447, and that of yellow 2°506.
From these data we may deduce three other equations, either by calculation,
or by measurement on the diagram (No. 2).
Eliminating green from the equations, we find—
565 B+ -485 Y=-307 R+-304W+°389Bk . . .. (8).
The mean of three observations by three different observers, gives—
‘573 B+:477 Y='313 R+:297 W+:390 Bk
Errors of calculation, —-008 B+-008 Y—-006 R+-:007 W—-001 Bk
The point on the diagram to which this equation corresponds is the intersection
of the lines BY and RW, and the resultant tint is a pinkish-gray.
Eliminating red from the equations, we obtain—

Calculation, . ‘533 B+:150 G+-317 Y='337 W+°663 Bk
By 10 observations, ‘537 B+°146 G+:317 Y=-337 W+°663 Bk : (4).
Errors, . . —004 +-004 — = —

Eliminating blue, ‘660 R+-:340 G=-218 Y+-108 W+-682 Bk
By 5 observations, °672 R+-328 G=-224 Y+-094 W+-:672 Bk} . : 3 : (5).
Errors, . - —012 +:012 —-006 +:014 +-008 i}

294 MR J. CLERK MAXWELL ON COLOUR,

Norte III.

On the Theory of Compound Colours.

Newton’s theorem on the mixture of colours is to be found in his Opticks,
Book I., Pt. IL., Prop. VI.

Ina mixture of primary colours, the quantity and quality of each being given,
to know the colour of the compound.

He divides the circumference of a circle into parts proportional to the seven
musical intervals, in accordance with his opinion of the divisions of the spectrum.
He then conceives the colours of the spectrum arranged round the circle, and at
the centre of gravity of each of the seven arcs he places a little circle, the area of
which represents the number of rays of the corresponding colour which enter into
the given mixture. He takes the centre of gravity of all these circles to repre-
sent the colour formed by the mixture. The hweis determined by drawing a line
through the centre of the circle and this point to the circumference. The posi-
tion of this line points out the colour of the spectrum which the mixture most
resembles, and the distance of the resultant tint from the centre determines the
fulness of its colour.

Newton, by this construction (for which he gives no reasons), plainly shows
that he considered it possible to find a place within his circle for every possible
colour, and that the entire nature of any compound colour may be known from
its place in the circle. It will be seen that the same colour may be compounded
from the colours of the spectrum in an infinite variety of ways. The apparent
identity of all these mixtures, which are optically different, as may be shown by
the prism, implies some law of vision not explicitly stated by Newton. This
law, if NEwTon’s method be true, must be that which I have endeavoured to
establish, namely, the threefold nature of sensible colour.

With respect to NewtTon’s construction, we now know that the proportions of
the colours of the spectrum vary with the nature of the refracting medium. The
only absolute index of the kind of light is the izme of its vibration. The length of
its vibration depends on the medium in which it is; and if any proportions are
to be sought among the wave-lengths of the colours, they must be determined for
those tissues of the eye in which their physical effects are supposed to terminate.
It may be remarked, that the apparent colour of the spectrum changes most ra-
pidly at three points, which lie respectively in the yellow, between blue and
green, and between violet and blue. The wave-lengths of the corresponding rays
in water are in the proportions of three geometric means between 1 and 2 very
nearly. This result, however, is not to be considered established, unless con-
firmed by better observations than mine.

The only safe method of completing NewrTon’s construction is by an examina-

AS PERCEIVED BY THE EYE. 295

tion of the colours of the spectrum and their mixtures, and subsequent calcula-
tion by the method used in the experiments with coloured papers. In this way
I hope to determine the relative positions in the colour-diagram of every ray of
the spectrum, and its relative intensity in the solar light. The spectrum will
then form a curve not necessarily circular or even re-entrant, and its peculiari-
ties so ascertained may form the foundation of a more complete theory of the
colour-sensation.

On the relation of the pure rays of the Spectrum to the three assumed Elementary Sensations.

If we place the three elementary colour-sensations (which we may call, after
Youne, red, green, and violet) at the angles of a triangle, all colours which the
eye can possibly perceive (whether by the action of light, or by pressure, dis-
ease, or imagination), must be somewhere within this triangle, those which lie
farthest from the centre being the fullest and purest colours. Hence the colours
which lie at the middle of the sides are the purest of their kind which the eye
can see, although not so pure as the elementary sensations.

It is natural to suppose that the pure red, green, and violet rays of the spec-
trum produce the sensations which bear their names in the highest purity. But
from this supposition it would follow that the yellow, composed of the red and
green of the spectrum, would be the most intense yellow possible, while it is the
result of experiment, that the yellow of the spectrum itself is much more full in
colour. Hence the sensations produced by the pure red and green rays of the
spectrum are not the pure sensations of our theory. Nrwrton has remarked, that
no two colours of the spectrum produce, when mixed, a colour equal in fulness
to the intermediate colour. The colours of the spectrum are all more intense
than any compound ones. Purple is the only colour which must be produced by
combination. The experiments of HELMHoLTz lead to the same conclusion; and
hence it would appear that we can find no part of the spectrum which produces a
pure sensation.

An additional, though less satisfactory evidence of this, is supplied by the ob-
servation of the colours of the spectrum when excessively bright. They then
appear to lose their peculiar colour, and to merge into pure whiteness. This is
probably due to the want of capacity of the organ to take in so strong an impres-
sion; one sensation becomes first saturated, and the other two speedily follow it,
the final effect being simple brightness. P

From these facts I would conclude, that every ray of the spectrum is capable
of progucing all three pure sensations, though in different degrees. The curve,
therefore, which we have supposed to represent the spectrum will be quite within
the triangle of colour. All natural or artificial colours, being compounded of the
colours of the spectrum, must lie within this curve, and, therefore, the colours
corresponding to those parts of the triangle beyond this curve must be for ever

VOL. XXI. PART II. 4k

296 MR J. CLERK MAXWELL ON COLOUR,

unknown to us. The determination of the exact nature of the pure sensations,
or of their relation to ordinary colours, is therefore impossible, unless we can pre-
vent them from interfering with each other as they do. It may be possible to ex-
perience sensations more pure than those directly produced by the spectrum, by
first exhausting the sensibility to one colour by protracted gazing, and then sud-
denly turning to its opposite. But if, as I suspect, colour-blindness be due to the
absence of one of these sensations, then the point D in diagram (2), which indi-
cates their absent sensation, indicates also our pure sensation, which we may
call red, but which we can never experience, because all kinds of light excite the
other sensations.

NEwTON has stated one objection to his theory, as follows :—‘ Also, if only
two of the primary colours, which in the circle are opposite to one another, be mixed
im an equal proportion, the point Z”’ (the resultant tint) “ shall fall upon the centre
O” (neutral tint); “ and yet the colour compounded of these two shall not be per-
fectly white, but some faint anonymous colour. For I could never yet, by mixing
only two primary colours, produce a perfect white.” This is confirmed by the ex-
periments of HeLMHoLTz ; who, however has succeeded better with some pairs of
colours than with others.

In my experiments on the spectrum, I came to the same result; but it ap-
peared to me that the very peculiar appearance of the neutral tints produced was
owing to some optical effect taking place in the transparent part of the eye on
the mixture of two rays of very different refrangibility. Most eyes are by no
means achromatic, so that the images of objects illuminated with mixed light of
this kind appear divided into two different colours; and even when there is no
distinct object, the mixtures become in some degree analysed, so as to present a
very strange, and certainly “ anonymous” appearance.

Additional Note on the more recent experiments of M. HELMHOLTZ.*

In his former memoir on the Theory of Compound Colours, M. HELMHoLTz
arrived at the conclusion that only one pair of homogeneous colours, orange-yel-
low and indigo-blue, were strictly complementary. This result was shown by
Professor GRASSMANN{ to be at variance with Newron’s theory of compound
colours; and although the reasoning was founded on intuitive rather than expe-
rimental truths, it pointed out the tests by which NewtTon’s theory must be verified
or overthrown. In applying these tests, M. HELMHoLTz made use of an appara-
tus similar to that;described by M. Foucavur,§ by which a screen of white paper

is illuminated by the mixed light. The field of mixed colour is much larger than
.
* Poccrnporrr’s Annalen, Bd. xciv. (I am indebted for the perusal of this Memoir to Professor
STOKES.)
+ Ib. Bd. Ixxxvii. Annals of Philosophy, 1852, Part II.
t Ib. Bd. lxxxix., Ann. Phil., 1854, April.
§ Ib. Bd. Ixxxvili. Moreno, Cosmos, 1853, Tom. ii., p. 232.

ea SP

AS PERCEIVED BY THE EYE. 297

in M. HeLMHoLTz’s former experiments, and the facility of forming combinations
is much increased. In this memoir the mathematical theory of NEwron’s circle,
and of the curve formed by the spectrum, with its possible transformations, is com-
pletely stated, and the form of this curve is in some degree indicated, as far as
the determination of the colours which lie on opposite sides of white, and of those
which lie opposite the part of the curve which is wanting. The colours between
red and yellow-green are complementary to colours between blue-green and violet,
and those between yellow-green and blue-green have no homogeneous comple-
mentaries, but must be neutralized by various hues of purple, 7.¢., mixtures of
red and violet. The names of the complementary colours, with their wave-
lengths in air, as deduced from FRAUNHOFER’S measurements, are given in the fol-
lowing table :—

Ratio of
Wave-lengths.

Complementary

Colour. Wave-length. Gsisae

Wave-length.

COS wb sy 0 2425 Green-blue, . 1818 1:334
Orange, .° . 2244 Blue e ty ans 1809 1:240
Gold-yellow, 2162 Bkie:* Pes 1793 1-206
Gold-yellow, 2120 Blties* 212 sit. 1781 1:190
Nellow, . . 2095 Indigo-blue, . 1716 1-221
Vellow,”. . 2085 Indigo-blue, . 1706 1-292
| Green-yellow, 2082 Violets" 2 1600— 1:301

(The wave-lengths are expressed in millionths of a Paris inch.)

(In order to reduce these wave-lengths to their actual length in the eye, each
must be divided by the index of refraction for that kind of light in the medium in
which the physical effect of the vibrations is supposed to take place.)

Although these experiments are not in themselves sufficient to give the com-
plete theory of the curve of homogeneous colours, they determine the most im-
portant element of that theory in a way which seems very accurate, and I cannot
doubt that when a philosopher who has so fully pointed out the importance of
general theories in physics turns his attention to the theory of sensation, he will
at least establish the principle that the laws of sensation can be successfully in-
vestigated only after the corresponding physical laws have been ascertained, and
that the connection of these two kinds of laws can be apprehended only when
the distinction between them is fully recognised.

298

MR J. CLERK MAXWELL ON COLOUR, AS PERCEIVED BY THE EYE.

Norte IV.

Description of the Figures. Plate VI.

. is the colour-diagram already referred to, representing, on NEwTon’s principle, the relations of

different coloured papers to the three standard colours—vermilion, emerald-green, and ultra-
marine. The initials denoting the colours are explained in the list at page 276, and the numbers
belonging to them are their coefficients of intensity, the use of which has been explained. The
initials H.R., H.B., and H.G., represent the red, blue and green papers of Mr Hay, and serve
to connect this diagram with No. (2), which takes these colours for its standards.

. represents the relations of Mr Hay’s red, blue, green, white, and yellow papers, as determined

by a large number of experiments at Cambridge.—(See Note II.). The use of the point D, in
calculating the results of colour-blindness, is explained in the Paper.

. represents a disc of the larger size, with its slit.
. shows the mode of combining two discs of the smaller size.
. shows the combination of discs, as placed on the top, in the first experiment described in the

Paper.

. represents the method of spinning the top, when speed is required.

The last four figures are half the actual size.

Colour-tops of the kind used in these experiments, with paper discs of the colours whose relations are

represented in No, 1, are to be had of Mr J. M. Bryson, Optician, Edinburgh.

PLATE VI Royal Soe Trans. Vol. XX.

NG:..6

FIG.3 FIG.5

HBOCX | ¥PB OL

—=\ Green 1-0

a OCT RON NY ac me
i= RIL3¥ } *UC O-4 fae, Bao eS Ses
Do oo, 627% Jec20 mM Poor | Yellow 2-5

fe Sh re (INS 2)

WEAK Johaston Bdinburgh

el.

(0 299q }

XIX.— Researches on the Amides of the Fatty Acids. By Tuomas H. Rowney,
Ph. D., F.C.S., Assistant in the College Laboratory, Glasgow.

(Read 2d April 1855.)

The following paper contains the details of some experiments upon the action
of ammonia on the oils and fats, of which a preliminary notice was published in
the Quarterly Journal of the Chemical Society of London.* The production of a
soapy emulsion by the action of ammonia on these substances has long been fami-
liar to chemists, but comparatively few accurate experiments have been made
upon the compounds formed. Bovutitay} long since examined the crystalline
substance obtained from olive-oil, which he called Margaramide, and mentioned
that similar compounds were obtained with the other oils, although he did not
examine them. More lately,t M. Bovis produced ricinolamide from castor-oil,
and showed that, by fusion with potash, it yielded caprylic alcohol and sebacic
acid; and still more recently,j he has obtained another fatty amide, which he
calls Isocetamide, by the action of ammonia on the fat of the purging nut of the
West Indies.

From these experiments, it is obvious that the Glycerides of the fatty acids
suffer the same decomposition when acted upon by ammonia, as their ethyl and
methyl compounds undergo when exposed to the action of this reagent, amides
being formed, and glycerine, methylic and ethylic alcohols being set free.

As the present communication contains a description of a considerable num-
ber of compounds obtained from different oils and fats; and as the method fol-
lowed to obtain and purify them was nearly the same in all cases, I shall here
describe it once for all, merely adding, under each oil, any particular remarks it
may be necessary to make.

The compounds were obtained by mixing one part by measure of oil, two
parts of alcohol, and four parts of strong solution of ammonia, in a stoppered
bottle, capable of holding twice the quantity, and placed in a moderately warm
situation, the stopper being tied with string, in order to prevent its being blown
out. The materials require occasional shaking, as, after standing some time,
they separate into two layers, the oil depositing, and the alcoholic and ammoniacal
fluid rising to the surface. After a certain time, varying with the nature of the
oil employed, it becomes covered with a whitish solid matter, which gradually

* Quarterly Journal, Chemical Society London, vol. vii., p. 200; 1855.
{t Comptes Rendus, December 26, 1843, p. 1846.

t Ibid., August 11, 1851, p. 141.

§ Ibid., November 6, 1854, p. 923.

VOL. XXI. PART II. 4 L

300 DR T. H. ROWNEY ON THE

increases in quantity. The oil at the same time becomes thicker, diminishes in
bulk, and finally both oil and ammoniacal liquor become nearly solid.

To purify the compounds, the pasty mass was collected upon a cloth filter,
washed with water, and then squeezed, to free it as much as possible from the
ammoniacal mother liquor. The squeezed mass was then dissolved in warm al-
cohol, and allowed to crystallize, again filtered through cloth, and washed, first
with dilute alcohol (made with equal parts of alcohol and water), then with wa-
ter, and the residue again expressed ; and this was repeated until it was obtained
free from a resinous matter which adheres obstinately to it. When pure, these
amides are perfectly white, and undergo no change by exposure to the air; but
if any of the resinous matter adheres to them, they speedily change colour, be-
coming yellow and resinous. The alcoholic mother liquors from which they have
been crystallized retain a considerable quantity of the substances dissolved in
them, which may be separated by the addition of water.

The original ammoniacal fluids, when evaporated on a water-bath, yield a
considerable quantity of a dark oily or resinous matter, mixed with some of the
amide.

The quantity of the crystalline compound obtained from each oil varied very
much, some yielding a considerable, and others a very small quantity. The time
required for the completion of the action also differs; with some the change is
readily and rapidly effected, but with others, and particularly with the drying
oils, long-continued digestion is required. The latter oils yield a very small pro-
portion of the crystalline compound, but a considerable quantity of resinous mat-
ter is obtained by evaporating the ammoniacal mother liquors.

The quantities of substance employed for analysis were dried in vacuo over
sulphuric acid, and the combustions were made with chromate of lead. The ni-
trogen determinations were principally made by Mr Mircuett’s modification of
Prxicot’s method, viz., caustic soda, to neutralize the excess of sulphuric acid,
infusion of logwood being used as the colouring matter.

The fusing point was taken by placing a small quantity of the substance in a
thin glass tube suspended in water contained in a metal vessel, which was heated
by a gas flame, and the temperature ascertained by immersing a thermometer in
the water. When the fusing point was found, the gas flame was removed, the
water allowed to cool, and the temperature at which solidification took place was
also observed. In the case of the amide which fused at 103° C., common salt
was added, in small quantities at a time, so as to raise the temperature gradually
until the fusing point was obtained.

The following are the oils that I have already examined, and several others
are in course of examination.

Almond oil, linseed oil, poppy oil, cod-liver oil, seal oil, and croton oil; also
almond oil and castor oil, after solidification by nitrous acid.

a

Wea PY eye;

Nn

AMIDES OF THE FATTY ACIDS. 301

Almond Oil.

Almond oil is readily acted upon by ammonia, and yields a large proportion
of the crystalline compound. This amide is very soluble in warm alcohol, and is
deposited from the solution in mammilated groups of crystals. It is insoluble in
water, and is separated from an alcoholic solution by dilution with water. It is
not decomposed by boiling with a solution of potassa, but fused potassa decom-
poses it, with the evolution of ammonia.

It commences to fuse at 79° C., and.is completely fused at 81° C.; when allowed
to cool after fusion it becomes solid at 78° C., but remains semitransparent.

The following numbers were obtained by analysis :—

‘7303 ... of carbonic acid, and

‘2612 grammes of substance gave
I.
2905 ... of water.

‘2612 grammes of substance gave
TI. < -7340 ... — of carbonic acid, and
"2877 -.. of water:
Il -2455 grammes of substance gave
“{:6910 ... of carbonic acid.
-2493 grammes of substance gave
IV.< 6970 ... of carbonic acid, and
-2830 ... of water,
Vv ‘2740 grammes of substance, burnt with soda lime, gave
“{:1980 ... of ammonio-chloride of platinum.
VI ‘3090 grammes of substance, burnt with soda lime, gave
*\ 2300 ... of ammonio-chloride of platinum.
I. II. ‘ELL. IV. V. VI.
Carbon, : 76°25 76.64 76.76 76:25
Hydrogen, . 12°35 12°19 aus 12°61 bie i
Nitrogen, . a at sa bis 4°52 4-67
Theory. Mean.
SaaS:
Gi 216° 76°86 76°47
He 35 12°45 12°38
N 14 4:98 4-59
0, 16 5-71 6:56
281 100-00 100-00

The ammoniacal mother liquors, when concentrated, did not yield much re-
sinous matter; but upon the addition of hydrochloric acid to the residue, an oil
separated, which was collected upon a moist filter, and washed with water. It
was then dissolved in ammonia, and chloride of barium was added; the precipi-
tate obtained was filtered, and washed with water. I endeavoured to crystallize
this salt from alcohol, but as it fuses into a resinous mass under the alcohol, and
adheres to the sides of the vessel, it could not be satisfactorily accomplished. This
property corresponds to that of oleate of baryta, and the analyses of it are suffi-
cient to show that it was in fact this salt, although in an impure state.

302 DR T. H. ROWNEY ON THE

The following are the numbers obtained :—

I ‘2550 grammes of substance gave
* | 0865 of sulphate of baryta.

ll 2227 grammes of substance gave
* | 0765 of sulphate of baryta.

‘2472 grammes of substance gave
III. ¢ -5485 of carbonic acid, and
2113 of water.
I. II. III. Mean.
Carbon, ade : 60°51 60°51 Cr 216 61:78
Hydrogen, aE sic 9°49 9°49 a 33 9:44
BaO 22-28 22°56 22°42 BaO 76°6 21-91
Oxygen, . ee aa ee 7°58 0, 24 6°87
100-00 349°6 100-00
Elaidine.

The solid fat or elaidine, obtained by passing nitrous acid into almond oil, is
readily acted upon by ammonia, and yields a large quantity of a crystalline amide.
Upon the addition of this reagent a deep red colour is produced ; and when the
action is completed, the whole is transformed into a pasty mass, which is collected
on a filter, washed with water, and expressed, by which means most of the
colouring matter is removed, the mass is purified by several crystallizations
from alcohol; and the amide is then obtained in brilliant groups of perfectly
colourless crystals, which are very soluble in alcohol but insoluble in water.
Elaidamide is decomposed by fusion with potassa, ammonia being evolved, but a
solution of potassa is entirely without action upon it. In this property it resem-
bles oleamide; indeed, all the fatty amides which I have examined agree in this
respect.

It begins to fuse at 92° C., and is completely fluid at 94°C.; upon cooling it
solidifies at 91° C. and becomes opaque.

The analysis gave the following results :—

[O72 of carbonic acid, and

‘2035 grammes of substance gave
i One
2323 of water.

*2100 of substance gave
II. 5865 of carbonic acid, and
°2405 of water.
III 4790 of substance gave _
; 0234 of nitrogen. 4
1. I. ML. y
Carbon, WOwte, 76.16
Hydrogen, 12°68 12.72 ae
Nitrogen, ele 4°88

au

AMIDES OF THE FATTY ACIDS. 303

Theory. Mean.

aaa
aa 216 76°86 76°44
Tgp 35 12:45 12°70
N : 14 4°98 4:88
O48 i. 16 5-71 5-98
281 100-00 100-00

Castor Oil.

I had commenced the examination of the action of ammonia upon castor oil
previous to the publication of M. Bovis’ paper upon the same subject, but as he
has described ricinolamide, and some of the products of its decomposition, I did
not continue my own experiments in that direction, though I made a partial ex-
amination of the mother liquor filtered from the amide.

When this filtrate is concentrated by evaporation, the addition of hydrochloric
acid to it causes the separation of an oil which was collected upon a moistened
filter, washed with water, and then dissolved in ammonia. The addition of
chloride of barium to this solution gave a precipitate, which was purified by re-
peated crystallizations from alcohol. It fuses under alcohol, and adheres to the
bottom of the vessel, but is more readily soluble in alcohol than oleate of baryta.
By analysis it was found to be ricinolate of baryta.

L { *3120 grammes of substance gave

“0995 ... of sulphate of baryta.
Il -2444 erammes of substance gave
; 0785 + of sulphate of baryta.
III °3333 grammes of substance gave
‘1070 ~~... ~— of sulphate of baryta.
‘3108 grammes of substance gave
IV. -6675 .., of carbonic acid, and
2533 ... Of water.
Ve Il. Iii. IV.
Carbon, . é ce aes ae 58°57
Hydrogen, . : ee a ake 9-05
Baryta, ; 20°95 210 21:09 ;
Theory. Mean.
Ce. 216 59°08 58°57
1 33 9:02 9:05
0. , Pesca: (0) 10:95 11°33
Ba O oy Y 16764 20°95 21:05
365°6 100-00 100-00

The cause of the presence of ricinoleic acid in the mother liquor is explained
by a remark made by M. Bovis in his paper, viz., that ricinolamide is decom-
posed by acids even in the cold. A small quantity of this amide must have been

VOL. XXI. PART II. 4M

304 DR T. H. ROWNEY ON THE

present in the mother liquor, and been decomposed by the addition of the hydro-
chloric acid. The presence of oleic acid in the mother liquor from oleamide may
be accounted for in a similar manner.

Palmine.

Palmine, obtained from castor oil by nitrous acid, when submitted to the
action of ammonia, behaves in a similar manner to elaidine. A large quantity of
amide is obtained, which is easily purified by crystallization from alcohol ; and,
when pure, it closely resembles elaidamide in appearance and properties.

It commences to fuse at 91°C., is completely fused at 93°C., and solidifies
at 89° C.

By analysis the following results were obtained :—

‘8760 ... of carbonic acid, and

*3295 grammes of substance gave
1!
°3840 ... of water.

‘2100 grammes of substance gave
II.< :5642 ... — of carbonic acid, and
“2211 2. OF water,
‘2115 grammes of substance gave
Tr ‘5630 ... of carbonic acid, and
"2280 ... of water.
Iv ‘4709 grammes of substance gave
s "0226 =... _ of nitrogen.
HE Il. Il. EV
Carbon, : : 72°50 Moo 72°59
Hydrogen, . : 11-73 12-04 11-97 ae
Nitrogen, . : a an ae 4:79
Theory. Mean.
oS=—_[{_—_ eR eKFKF«==__—_._
Caen ik 72°72 72-79
i. 35 11-78 11°94
N 14 4-71 4:79
0, 32 10°79 10-41
297 100-00 100-00

Linseed Oil.

Linseed oil requires long digestion with ammonia before it is acted upon, and
it yields only a small quantity of amide, the greater portion of the oil being con-
verted into a resinous matter, from which it is exceedingly difficult to purify the
amide. It is insoluble in water, but very soluble in warm alcohol; and is de-
posited from this solution on cooling in mammillated groups of crystals, which,
when dry, form a light, bulky, colourless, crystalline substance. The crystals
soon acquire colour if they have not been thoroughly separated from the resin-

eT

SOP 9 — AB e 09 Re ee

oe

a

AMIDES OF THE FATTY ACIDS.

ous matter.
when cooled to 97° C.

The following results were obtained by analysis :—

305

The fusing point was found to be 100°C., and it became solid again

‘2400 grammes of substance gave
I. ‘6628 of carbonic acid, and
2815 of water.
2200 grammes of substance gave
II. -6065 of carbonic acid, and
2577 of water.
Ul -2128 grammes of substance gave
~ 1698 of ammonio-chloride of platinum.
Iv ‘2423 grammes of substance gave
* | +1948 of ammonio-chloride of platinum.
Te Il. II. IV.
Carbon, 75°31 75:18
Hydrogen, 13°03 13-01 sais bss
Nitrogen, 5:01 50:4
Theory Mean.
C1 1204 75°83 75:25
By, bas 13-01 13-02
N 14 5°20 5:03
0, 16 5:96 6-70
269 100-00 100-00

These results correspond with the formula of margaramide, with which the
properties of the substance also agree.

Poppy Oil.

Poppy oil is more readily acted upon than linseed oil, and yields a consider-

able portion of amide, but also much resinous matter.

The amide obtained is

more easily purified than that from linseed oil, but still repeated crystallizations
from alcohol are necessary in order to free it from resin.

It is very soluble in alcohol, and crystallizes in mammillated groups.

fusing point was found to be 103° C.
The analysis of this compound shows that it also was margaramide :—

Carbon,
Hydrogen,
Nitrogen,

‘1918 grammes of substance gave

-5300 of carbonic acid, and
*2248 of water.
2100 grammes of substance gave
-5805 of carbonic acid, and
°2445 of water.
°3215 grammes of substance gave
0168 of nitrogen.
I. Il. II.
75°36 75°38
13°01 12:93

5:24

Its

Mean.
19°37
12:97

0°24

306 DR T. H. ROWNEY ON THE

Croton Oil.

Croton oil yields a small quantity of amide, and the mother liquor when con-
centrated by evaporation contains a dark oily substance. The amide requires
several crystallizations from alcohol to render it pure. It crystallizes in mam-
millated groups, and when dry is light and bulky. Its fusing point is 100° C.

The analysis of this substance gave the following results :—

‘2258 grammes of substance gave
it °6235 ... of carbonic acid, and
2598 ... of water.
‘2153 grammes of substance gave
1 ‘5962 ... of carbonic acid, and
"2528 ... — of water.
lll *2900 grammes of substance gave
"|. 0142” ~~... - of nitrogen,
i Il. III. Mean.
Carbon, . OO 75°52 4 75°41
Hydrogen, . yale: ho 13-04 soe 12:91
Nitrogen, . : ae +7 4°83 4:83

The nitrogen in this analysis is rather too low, and unfortunately I had no
more substance with which to make another determination; but, however, the
results altogether are sufficient to show that the substance was margaramide.

Seal Oil.

Seal oil is readily acted upon by ammonia, and yields a considerable quantity
of amide; the mother liquor contains a large amount of resinous and oily matter,
which separates by evaporation. The amide is readily purified by crystalliza-
tion from alcohol, in which it is very soluble. When pure and dry, it forms a
rather dense and crystalline powder, fusing at 82° C., and is transparent when
cold.

By analysis the following numbers were obtained, which correspond with
those for oleamide, though the hydrogen is somewhat too high.

‘2125 grammes of substance gave

I.¢ :5980 ... __ of carbonic acid, and
(2475 ... of water.
U ‘2133 grammes of substance gave
“*¢'5995 ~~... of carbonic acid, and
2475 ... of water.
II *3145 grammes of substance gave
“OLS. ..5 af nitrogen.

Iv, f{ 3255 grammes of substance gave
“(0158 ... — of nitrogen.

AMIDES OF THE FATTY ACIDS. 307

I Ile III. 1V. Mean.

Carbon, : 76-74 76-65 e: ys 76°70
Hydrogen, ; 12°94 12°89 phe Aid 12:92
Nitrogen, : ae fe 5-02 4°85 4:94

Cod-Liver Oil.

Cod-liver oil requires to be digested for a considerable time with ammonia
before it is acted upon. It does not yield very much amide, but a considerable
quantity of an oily and resinous matter is obtained from the mother liquor. It
is very soluble in alcohol, and when dry presents similar appearances to the
amides previously described; but its analysis gives results which at present I
cannot explain, and on that account I have not given it either a name or formula.
It fuses at 93° C., and becomes solid and transparent at 91° C.

The following are the numbers obtained :—

-5960 ... Of carbonic acid, and

-2150 grammes of substance gave
iE.
"25384 ... of water.

‘2114 grammes of substance gave
‘5875 —... of carbonic acid, and
2465 ... of water.

II

III ‘4740 grammes of substance gave
"(:0205 .... of nitrogen.

‘4360 grammes of substance gave

iy “O93: 4... of nitrogen.
y_ { 3305 grammes of substance gave
0142 =... _~—s of nitrogen.
if II. III. IV. V. Mean.
Carbon, . 75:60 75°79 se 36 fai 76°70
Hydrogen, . 13:03 12:95 a: ae Be 12-99
Nitrogen, . ee sie 4°32 4:42 4:29 4°34

On comparing these results with those obtained from the other amides, it will
be seen that the carbon and hydrogen would correspond with the formula for
margaramide, but the nitrogen is nearly one per cent. too low; the fusing point
is also much lower than that of this amide. It likewise remains transparent
when cold, which is a property belonging to oleamide, whilst the margaramide
becomes opaque and somewhat crystalline when cold. It is my intention to
make another examination of this oil, in order to ascertain the cause of these
unsatisfactory results.

As it is my intention to continue this investigation, and also to examine the
products of decomposition of these amides, I shall at present confine myself to a
few remarks.

From the results of the analyses it appears that linseed, poppy, and croton
oils yield margaramide, whilst oleamide is obtained from almond and ‘seal oils;
and, according to M. Bours’ experiments, ricinolamide is obtained from castor

VOL. XXI. PART II. 4N

308 DR T. H. ROWNEY ON THE AMIDES OF THE FATTY ACIDS.

oil; also from almond and castor oils, after solidification by nitrous acid, we ob-
tain elaidamide and palmamide, these amides being isomeric with oleamide and
ricinolamide.

The only other point to which I shall refer is the temperature at which these
amides fuse. M. Bouttay states that the fusing point of margaramide is 60° C.,
but, according to my own experiments, I have found it to be as high as 103° C.,
though in the cases of the amides from linseed and croton oils, it was as low as
100° C., but this arose from these substances not being perfectly pure; and it is
probably a similar cause that occasions the error of M. Bouttay. I am also in-
clined to think that the fusing points of ricinolamide, 66° C., and isocetamide,
67° C., are too low. Isocetamide only differs by 2C, H, from margaramide, the
fusing point of which is 103°; and ricinolamide is closely related to oleamide,
which has a fusing point of 82°C., and the isomeric amides, palmamide and
elaidamide, both fuse at about 94° C.

In conclusion, I have to express my thanks to Dr AnprErson for the use of his
laboratory, and also for many suggestions during the progress of this investi-
gation.

O_O

of 4

rte eatdn exert

( 309 )

XX.—On the Volatile Bases produced by Destructive Distillation of Cinchonine.
By C. GrevVILLE Wiuiams, Assistant to Dr ANDERSON, University of Glasgow.

(Read 16th April 1855.)

The history of the organic bases has now become as ardent an object of study
among chemists as that of the as yet far more numerous group of acids ; and it
is generally admitted that the information obtained has been no less important
and interesting. Of all organic alkaloids, those of opium and the cinchona barks
doubtless occupy the first rank, whether we regard their value as remedial agents,
or the remarkable facts which have been ascertained connected with their atomic
relations, and the influence exerted by the latter, upon the theory of the science.

It has long been known, that many of these fixed oxidized alkaloids may, by
destructive distillation and analogous processes, be made to yield an entirely dif-
ferent, and no less interesting class, distinguished from the first by their volati-
lity, and the absence of oxygen.

None of the bases produced by such decompositions have attracted more
attention than chinoline; not that, like aniline, it has yielded any compounds
which, from their perfect analogy with those of ammonia, the beauty of their
salts, or any peculiarities in their coloured reactions, are interesting per se; on
the contrary, the highness of its atomic weight and boiling point, the small
tendency of its salts to form well-defined crystals, and the absence of any spe-
cialties in its behaviour with reagents, make it entirely dependent on its stochio-
metrical relations, and on its supposed intimate connection with quinine, cin-
chonine, and strychnine, for the interest it possesses. While chemists believed
that those alkaloids, minus a certain amount of hydrogen and carbonic acid,
yielded chinoline, a very simple relation appeared to exist between them, a
simplicity that gave interest to the subject; but when it was announced that,
the leukoline of coal tar was identical with chinoline; and still more, that the
product of the action of iodide of methyl on leukol, when converted into a
hydrated oxide was isomeric with quinine, if not the same substance, many
were found who believed that the artificial production of the chinchona alkaloids
would soon become a common process. But the evidence of the identity of leukol
with chinoline was contradictory ; Hormann first asserted, in his Researches upon
the Bases of Coal Naphtha, that their behaviour with chromic acid demonstrated
their dissimilarity, while subsequently,* Lizpie announced, upon the authority of

* Chemical Gazette, vol. iii, p. 251, 1845. Proceedings of Chem. Soc., April 7, 1845,
VOL. XXI. PART II. 40

310 MR C. G. WILLIAMS ON THE VOLATILE BASES

experiments made by Hormann, that they had been ascertained, by crucial ex-
periments upon perfectly pure substances, to be the same. In the meantime,
chinoline is found to be produced from other bodies, among which may be men-
tioned thialdine and trigenic acid.

But if we examine the published analyses of chinoline, great discrepancies
appear, so much so, that GERHARDT places two formule by the side of the analy-
tical results, namely, C,, H, Nand C,, H, N. On looking at the experimental
as compared with the theoretical results, it appears that the analyses, if we except
Hormann’s, which were made upon the base from coal naphtha, agree with neither
view. Bromets, in a paper on chinoline, published about ten years since,* gave a
formula which is not admissible, and his numbers, recalculated according to the
new atomic weight of carbon, do not agree with either of the formule given by
GERHARDT, the carbon being two per cent. too low. The analysis of the bases
themselves in the present case, is by no means a satisfactory method of establish-
ing their constitution, for when entirely freed from other substances, they are ex-
tremely incombustible ; and when it is considered that the two formulze only cause
a difference of 2 of a per cent. of carbon, it will be seen that the platinum salts
afford a far better means of distinguishing them, the addition of C, H, causing a
rise of two per cent. in the carbon. But even this method could not afford a
result, where a mixture of substances was present, unless the salt had been frac-
tionally crystallized, which does not appear to have been done by either of the
chemists who have worked on chinoline; Bromeis obtaining far too much carbon
for the 18, and as much too little for the 20 C base; the same remark applying,
though less strongly, to the results of GERHARDT, whose numbers approach, with
regard to the carbon, nearer to the formula C,, H, N, than C,, H, N, although he
obtained greatly too much hydrogen for either.

Before I had seen the discordant analyses in the Traité de Chimie Organique of
the last-named chemist, I had suspected, upon theoretical grounds, that chinoline
was not a homogeneous substance. In the first place, it appeared unlikely that
in an operation with so powerful a reagent as caustic potash, acting at an elevated
temperature upon so complex an organic molecule as the base alluded to, that
only one substance, and that of so high an atomic weight as chinoline, would be
found. I had ascertained, by a great number of experiments on nitrogenized
substances, both animal and vegetable, that in no case could they be distilled, either
alone or with alkalies, without formation of the pyrrol of Runex, and on trying
the same experiment with cinchonine, a similar result presented itself; and this
alone was a strong evidence of the truth of the supposition alluded to. But the
chief reason which led me to doubt the homogeneity of chinoline was, that I was
unable to obtain it with a constant boiling pomt. I will not lay stress upon an

* Lizzie’s Annalen, Bd, 52, p. 130.

ll

PRODUCED BY DISTILLATION OF CINCHONINE. 311

idea which often forced itself upon me, namely, that there might be some basic
product besides pyrrol, characteristic of the destructive distillation of nitrogenized
organic bodies, because I had no decisive proof; but I may mention that there is
a most intimate connection between the volatile bases best known, produced at
very high temperatures. For with all the substances as yet examined, such as
bones, shale, &c., the complete series of bases homologous with pyridine has been
found, and though, in the case of coal naphtha, only picoline has as yet been de-
tected, I believe I shall shortly be able to prove, that other members of that series
exist in it. It will be seen that, if these views are correct, indigo and piperine
ought to yield more than aniline in the one case, and piperidine in the other,
which, in the present state of our knowledge, does not appear to be the case;
while, on the other hand, if we study the experimental results yet obtained
from coniine, it will scarcely be too much to conclude that it is a mixture.
In order to give a decisive answer to the question raised by these facts, it be-
comes necessary to examine, somewhat minutely, several of the bases said to be
the sole product of the destructive distillation of certain alkaloids, and other nitro-
genous bodies ; and the following may be regarded in the light of a small contri-
bution to the subject.

It being evident that a considerable amount of material would be required, I
subjected 100 ounces of cinchonine to destructive distillation with potash, by
small portions at a time, in an iron alembic, the products being collected in a well
cooled recipient, but notwithstanding the large scale on which the experiments
were carried on, some difficulty was found in procuring enough of certain portions
for examination.

There were several phenomena observed during the preparation of the crude
chinoline, which are not described in the works to which I have had access; but
as these are not immediately connected with the subject under consideration,
they need not be further alluded to, except to mention that whatever precautions
were taken in the distillation, pyrrol was, nevertheless, constantly found, and ad-
hered to the crude chinoline with such tenacity, that it required two days’ boiling
of the acid solution to effect its complete removal.

The base was separated from the simultaneously-produced water, by means
of caustic potash, which was added in sufficient quantity to prevent any remain-
ing dissolved. After separation, by means of a tap funnel, from the dense alkaline
solution, it was again digested with sticks of the potash, until no more water was
removed. The general process for separating these volatile bases from non-basic
and other impurities, has been so often described, that it becomes unnecessary to
dwell upon it further.

On distilling perfectly dry chinoline, with a thermometer in the tubulature of
the retort, ebullition was found to begin at about 300° F. (149 C.), although no

* I have inserted the centigrade degrees (in round numbers), for convenience of those accustomed
to that scale,

312 MR C. G. WILLIAMS ON THE VOLATILE BASES

distillate could be procured for nearly fifty degrees above that point, until after
several rectifications, when it was found that fractions could be obtained at
every ten degrees from about 300° to 500° F. (183° to 260° C.) It was therefore
determined to submit the whole of the chinoline in my possession to a systematic
fractionation; and by the use of very small retorts, and tolerably perfect conden-
sation, I was enabled to effect ten fractionations even of the smaller portions;
and with the distillates of the higher boiling points, which were larger in quantity
than the others, twelve, and in some cases even thirteen were effected. Altogether
this procedure involved, with those afterwards found necessary, at least 200 dis-
tillations. By this means, fractions were obtained as low as between 310° and
320° F. (154° to 160° C.), and as high as 520° F. (271° C.). When it is considered
that the boiling point of chinoline is 460° F. (238° C.), it will be seen that it was
not going too far to conclude that evidence was obtained of the correctness of the
suspicion previously mentioned; and it is submitted, that the following experi-
ments prove that cinchonine by distillation with potash yields at least seven bases
instead of one, as has been generally believed. It might be imagined that they
would all be found to consist of homologues of chinoline, but it will be shown
that this is not the case, and that two distinct series are present, one homologous
with chinoline, and the other isomeric with the aniline series, and identical in
composition with the group found by Dr AnDERson in bone oil,* and afterwards
by myself in the naphtha, from the bituminous shale of Dorsetshire.}

Before proceeding to the details of the experiments, it is proper to mention,
that although the researches were commenced in London, and afterwards partially
carried on in my own laboratory in Glasgow, that on becoming assistant to Dr
ANDERSON, he not only permitted me to make comparative experiments with his
bases, but gave me every possible opportunity of pursuing the investigation. In
my first experiments, and before I had any considerable quantity of chinoline at
my disposal, [ endeavoured to obtain some insight into the nature of the fluid by
fractionally crystallizing the platinum salts according to the method described in
a paper on the presence of pyridine in the basic portion of the naphtha from the
Dorsetshire shale. +

The results, which are given below, were too remarkable not to be carried out
more in detail; but the large quantity of platinum required to effect a perfect
separation, prevented me from availing myself of this method of working, and I
was forced to fall back upon the tedious and wasteful process of fractional distil-
lation.

To obtain the platinum salts, a certain quantity of hydrochlorate of chinoline,
freed from pyrrol, by boiling its acid solution for a long time, was evaporated on
the water-bath, as long as water came off, but it could not be obtained in a per-

* Trans. Royal Soc. Edin., vol. xvi., part iv. + Quart. Jour, Chem. Soc., Lond., July 1854.
+ Phil. Mag., September 1854.

PRODUCED BY DISTILLATION OF CINCHONINE. 315

fectly dry state. The mass dissolved immediately in strong alcohol, showing the
absence of ammonia. To the solution, a slight excess of bichloride of platinum
was added, when a voluminous precipitate (@) was obtained ; the mother liquor of
a, on evaporation, gave a crop of crystals 6, the fluid from which gave another
crop ¢.

The precipitate a was the first examined ; it was dissolved in hot water, and
on cooling deposited a crop of crystals, which was evidently a mixture, for it con-
sisted of large orange crystals a’, and exceedingly small needles a*; a’ was capable
of being perfectly freed from @* by sifting through muslin; the latter was not, how-
ever, absolutely free from small fragments of a’, and was therefore further ex-
amined, as will be presently seen.

5-295 grains of a? dried at 212° gave
1625" --- platinum,
or 30°69 per cent., a number intermediate between lutidine and collidine.

The mother liquid of the crops a* and a‘ gave a crystalline deposit a’, which

had the same crystalline form and appearance as a’, but a little more brilliant in

colour.

4:955 grains of a? dried at 212° gave
1520 ... platinum,

or, 30°67 per cent. It will be seen, therefore, that a’ and @’ agree not only in
form but also in composition.
The mother liquid of @ on evaporation over sulphuric acid, gave another crop
a”, which was, therefore, the third crop from a.
2-245 grains of a” dried at 212° gave

‘740 ~~... ~— platinum,
or 32°96 per cent., which is almost exactly the theoretical percentage in picoline for
Experiment. Theory. (Picoline.)
32°96 32°94.

It has been said that a* contained a little of a> intermixed; it was therefore
treated with hot water, which separated it into two portions, one less soluble a’,
and a solution which on cooling deposited a crop of crystals a°. The portion of
a° which was present was very minute, and remaining in solution did not effect
the results given by a’ and a’.

3°205 grains of a° platinum salt gave
1010... platinum,
or 31°51 per cent.
Experiment. Theory. (Lutidine.)
— 3151 31-51

3°970 grains of a® platinum salt gave
TPO lee See platinum,

or 28°96 per cent., a number intermediate between chinoline and lepidine, presently
VOL. XXI. PART Il. Ave:

314 MR C. G. WILLIAMS ON THE VOLATILE BASES

to be mentioned. The mother liquid, on treatment in the manner described in my
former paper, namely, exposure to a desiccating surface gave a crop a’,

2°780 grains of platinum salt a’ gave
OOO) jl b. x platinum,

or 31:65 per cent.

Experiment. Theory. (Lutidine.)
50

31°65
The mother liquor of @ gave 6 on evaporation,

5'327 grains of platinum salt b gave
1:635 P: platinum,
or 30°70 per cent., being almost exactly the same result as @ and a’.

The mother liquor of 6 gave a crop of white needles, the nature of which I
have not yet been able perfectly to comprehend. I have, however, observed
them to exist in the very last crops of many platinum salts of different kinds,
more especially when evaporated by the aid of heat. They are soluble in hot
water, and at a red heat leave metallic platinum. They do not defiagrate when
thrown into melted nitre. Solution of potash does not decompose them, the
aqueous solution is not precipitated by alcohol; the solution in boiling water
precipitates nitrate of silver.

2°182 grains gave on ignition

1672 ... of platinum,
or 73°50 per cent. :

When it is considered that even protochloride of platinum requires 76°6, it will
be seen that this experiment does not throw much light on their nature.* The
quantity I have as yet been able to obtain has been too small to allow of a further
development of their history.

The mother liquid of these crystals yielded a resin not further examined, which

was the last product of the mother liquid of a.

These results,—although the numbers obtained are as close as could be expected
to the theoretical values, and prove that the bases to be described more fully fur-
ther on, were not produced during the distillations,—were, of course, quite insuffi-
cient to settle the points sought to be determined : it became necessary therefore
to examine minutely each of the fractions obtained by the distillations previously
alluded to. It may be mentioned here, that in order to remove any objections
that might be urged as to the bases being produced from the decomposition of
nitrogenous impurities existing in the cinchonine employed, an analysis was
made with the following results,—

20°56 aa) carbonic acid and
5°28 on, water.
Il { 3:0 Sm eee cinchonine dried at 212° gave
5°64 tas water.

7°25 grains of cinchonine dried at 212° gave
I

oe - eP ee ee

PRODUCED BY DISTILLATION OF CINCHONINE. 315

I. IL. Calculation.
4; [=e ——_——
Carbon, 77:34 ed 1092 C,,' «240
Hydrogen, 8-09 7:80 Cis. oe 2s
Nitrogen, ae A 9:09) UN, 28
Oxygen, ee 2: oe Ieee 08 16

308

The fact of the two series of bases present not being homologous with each
other, rendered a considerable amount of labour necessary before they could be
purified sufficiently for analysis, the presence, in very small quantity, of a base
of the one series altering to such an extent the composition of the other, that no
confidence could be placed in an analysis, unless extreme care was taken in the
purifications, and the small amount of material at my command naturally added
considerably to the difficulties with which I had to contend.

Lutidine —It soon became evident that the third base discovered by Dr ANDER-
son in the animal oil of Dippel, and to which he gave the name of lutidine, was
that which most prominently presented itself in the first fractions. It was
subsequently ascertained that pyridine and picoline were present in exceed-
ingly small quantities, and to attempt their isolation would have been useless.
The only evidence I have to show of the presence of pyridine is an isolated result,
being the composition of the second crop of crystals of platinum salt obtained
from the first fraction during the earlier rectifications, and before the pyridine could
have escaped, as being present in such small quantity it was sure to do event-
ually, from the difficulty of effecting perfect condensation in an operation invol-
ving the changing of the receiver every few minutes.

2:740 grains of platinum salt, second crop, from fraction boiling below 330° F. (165° C.)’
(fourth distillation) gave
‘948 grains of platinum,

or 34°6 per cent.
Experiment. Theory. (Pyridine.)
34°6 34°6
The difficulty experienced in obtaining the lutidine sufficiently free from the
bases above it, to enable a good result to be obtained, will appear from the ana-
lyses below, which were made upon platinum salts from fractions which had been
rectified the number of times prefixed to each result.

Ist Rect. 2d Rect. 4th Rect.
—<—— ===
Carbon, ; is 29:40 28°89 27:10 27°20
Hydrogen, . : 3°73 3°84 3°30 3°28
Platinum, : : 30°85 30°63 30°83

It was evident, therefore, that although the numbers were gradually becoming
nearer to those required for lutidine, that, nevertheless, many more rectifications,
. would be necessary before any close approximation could be expected. The
small quantity of fluid was therefore, with careful management, made to pass

316 MR C. G. WILLIAMS ON THE VOLATILE BASES

through nine perfect fractionations, at the end of which a base was obtained, if
not absolutely free from the more highly carburetted bases, at least so nearly,
that, on analysis—

5-265 grains of base, boiling between 320° and 330° F. (160°-165° C.), gave
15:190 carbonic acid, and

4:040 Be water,
or per cent.

Experiment. Theory.
—— —
Carbon, . ; 78-68 78°50 Ca 84
Hydrogen, . ; 8-52 8-41 Hi, 9
Nitrogen, . ; 12°80 13°09 N 14
100-00 100-00 107

This, then, is the third occasion in which lutidine has been observed, the other
two being, first, in bone oil, where it was discovered ;* and, secondly, among the
bases produced by destructive distillation of the bituminous shale of Dorsetshire,
where I found it among others of the same series.

The analysis of the base from those sources yielded the numbers following,
where they are compared with the same base from cinchonine.

(Dr ANDERSON, from (GREV. WILLIAMS from (GRrEV. WILLIAMS from
Bone-Oil, mean.) Shale Naphtha, mean.) Cinchonine.)
Carbon, ! : 78°45 78:68 78°68
Hydrogen, . 2 8°81 8°55 8°52
Nitrogen, . : 12°54 12°77 12-80
100-00 100-00 100-00

Before converting the fraction which gave the analysis mentioned above into
platinum salt, in order to confirm the result, it was once more distilled, that portion
only being received which came over between the same points; the double salt
then obtained gave the following numbers :—

9-025 grains platinum salt, boiling between 320° and 330° F. (160°-165° C.), tenth rec-
tification, gave ;

8-915 ... carbonic acid, and
2°730 ... water.
5°715 grains platinum salt gave
1:780 ... platinum,
corresponding to—
Iixperiment. Calculation.
AR A RS
Carbon, ; : 26°94 26°81 Co 84
Hydrogen, . ‘ 3°36 319 He 10
Nitrogen, . - a 4:49 N 14
Chlorine, : is 34:00 Cl, 106-5
Platinum, . : 31:14 31:51 Pt 98-7
100-00 100:00 313-2

* Trans. Royal Soc. Edin., vol. xx., part ii. + Quart. Journ. Chem, Soc. Lond., 1854.

PRODUCED BY DISTILLATION OF CINCHONINE. alg

The following analyses of the platinum salts of lutidine relate to the mean
results of Dr ANDERSON from Dippel’s oil, and to a salt obtained by me from
shale naphtha; the latter contained, however, a little picoline, which lowered the
carbon.

(Dr ANDERSON from (GREV. WILLIAMS from
Dippel.) Shale Naphtha.)
Carbon, : : : 26°35 26°14
Hydrogen, . : : 3°23 3°16
Platinum, . : : 31°50 31:76

Although the results detailed leave no doubt as to the identity of this base, it
was, nevertheless, determined to place the fact beyond dispute, by obtaining a
methyl compound. When the base is mixed with twice its bulk of iodide of methyl,
it becomes heated, boils, and almost immediately solidifies into a mass of crystals
of hydriodate of methyl-lutidine-ammonium. This substance, as obtained from
the chinoline bases, is excessively soluble in water and alcohol, but insoluble, or
nearly so, in ether. On evaporating the spirituous solution of the hydriodate to a
syrupy consistence, it retains that state for a considerable time, if not disturbed ;
but immediately it is touched, long and beautiful needles shoot quite across the
vessel, and finally the whole becomes a mass of crystals.

As some difficulty presented itself in purifying the crystals from a brown pro-
duct which contaminates it, in common with analogous salts from almost all
volatile oily bases subjected to the same treatment, it was converted into a plati-
num salt. To effect this the crystals were dissolved in water, the iodine preci-
pitated by nitrate of silver, excess of hydrochloric acid was then added, and the
solution filtered; the filtrate, after addition of chloride of platinum, yielded a
crop of fine crystals.

4-490 grains of platinum salt of methyl-lutidine gave
360 3.) platinum:

Experiment. Theory.
30°29 30°16

On treating the iodide of methyl-lutidine with potash, no odour of a volatile
base is evolved, showing it to agree in constitution with Hormann’s fourth class,
and serving also as corroborative evidence of the identity of it with the bone-oil
alkaloid.

Collidine.—It now became desirable to ascertain if the next base of the picoline
series was present, and the following experiments leave no doubt that collidine
exists among the products of the distillation of cinchonine with potash.

Collidine is one of the bases discovered by Dr ANDERSON in Dippel’s oil,* and
found a few weeks subsequently by me in shale naphtha. At the time I exa-
mined the latter I was unacquainted with Dr ANDERSon’s experiments; but when
I became his assistant, abundant opportunities were afforded me of comparing

* Trans. Royal Soc. Kdin,, vol. xxi., part 1.
VOL. XXI. PART Il. 4Q

318 MR C. G. WILLIAMS ON THE VOLATILE BASES

the bases I had obtained from both sources with the originals discovered by him,
and the result is, that no doubt remains in my mind of their identity, and I have
the satisfaction of knowing that Dr AnprErRson is of the same opinion.

The quantity of collidine in the crude chinoline, from 100 ounces of cincho-
nine, was found to be so small that it became impossible to analyse the base
itself; the platinum salt, however, was obtained nearly in a state of purity.

The boiling point of collidine is stated, in the paper before adverted to, to be
354 F. (179° C.); and on converting the fraction between 350° and 360° F.
(177'-182° C.), of the tenth rectification into platinum salt, the following numbers
were obtained,—

9:895 id carbonic acid and

9-290 grains of platinochloride of collidine gave
\f
2°960. "|... _ svater.

11, { 3405 grains of platinochloride of collidine gave
“(E020" ).°.>) platinum;

2°400 grains of platinochloride of collidine gave ~
III. ; aa
‘725 =... platinum.

I. and II. III. Calculation.

ee

Carbon, : " 29-04 sige 29-33 Cry 96

Hydrogen, . : 3°54 oor 3°66 5 ie 12

Nitrogen, i : way fall 4:31 N 14
Chlorine, , a sek 32°54 Cl, 106°5
Platinum, : : 29°97 30°2 30°16 Pt 98°7
100-00 327°2

Collidine was found to exist also in fractions boiling at higher points; for the
next fraction to that last analysed gave a salt which yielded, in a platinum de-
termination, the annexed numbers :—

7-095 grains of platinochloride of collidine from fraction boiling between 360° and 370° F.
(182° to 187° C.), tenth rectification, gave

2145 ... platinum,
or 30°23 per cent.
Experiment. Theory. (Collidine).
30°23 30°16

One cause of the difficulty of obtaining the Dippel’s oil series from cinchonine
in a state of purity, was the presence of some basic substance decomposable by
nitric acid of moderate strength. It was only towards the end of the investiga-
tion that this was ascertained. If it had been known at the outset, many of the
distillations, and consequently much loss of material, might in all probability
have been saved.

The fraction boiling even as high as 390° F.(199°C.) contained a large proportion —
of collidine ; but it was necessary to act upon it with rather weak nitric acid, and
then reobtain the base by distillation with potash before converting it into plati- —

‘\

PRODUCED BY DISTILLATION OF CINCHONINE. 319

num salt. After proceeding in this manner, a fine crop of crystals was obtained,

which, on combustion with chromate of lead, gave the annexed numbers :—

9-046 grains of platinum salt from fraction boiling between 380° and 390°F. (193°-198°C.),
after treatment with nitric acid (ninth rectification), gave

9:805 ... carbonic acid and

2:900 ... water.

5110 grains of platinochloride of collidine, same as last, gave
1525 ... platinum.

corresponding to

Experiment. Calculation.
pee SA eee BS)

Carbon, 5 ao yu 29°56 29°33 Cie 96
Hydrogen, . ‘ ; 3°56 3°66 He 12
Nitrogen, . , ‘ a 4°31 N 14
Chlorine, . A é er 32°04 Cl, 106°5
Platinum, . : ; 29°84 30°16 Pt 98°7

100-00 327°2

The numbers obtained in the analyses of the platinum salt of collidine from
Dippel’s oil, is in the following table compared with those given above and the
theoretical ones.

Dippel’s Oil, GREV. WILLIAMS,

Dr ANDERSON. from Cinchonine.
I: HI I, Il. If. Theory.
Carbon, ‘ : 28°77 29:00 29:04 29-56 cae 29°33
Hydrogen, . : 3°57 3°63 3°54 3°56 ae 3°66
Nitrogen, . ; erie nei th abn Rat 4°31
Chlorine, 5 bee Res 5 aie ae 32°54
Platinum, . : 30°33 30°03 29°97 29°80 30°2 30°16
100-00

The collidine thus obtained, treated in the usual manner with iodide of me-

thyl, yields a finely crystallized hydriodate of the ammonium base, although the

reaction is less energetic than in the case of lutidine.

Chinoline.—In examining the fractions at temperatures above those already
described, it appeared that the series which then presented itself was not homo-
logous with that of which lutidine and collidine are members. In fact, about
400° F. (204° C.) the proportion of hydrogen in the platinum salts began to lower
so rapidly, that it was evident that the chinoline of Geruarpt was the next base.

In the course of the rectifications, the relative positions of the bases undergo
considerable changes, for while, in the eighth rectification, the portion of fluid
boiling about 420° F. contained some lepidine (the 20 carbon base, to be de-
scribed further on), after four more distillations, it had gone higher up, and
nearer to its correct boiling point, and then the position in the series of frac-
tions formerly occupied by a mixture of chinoline and lepidine became held
entirely by the former.

320 MR C. G. WILLIAMS ON THE VOLATILE BASES

Chinoline is the chief constituent of all the fractions boiling between 420° and
470° F. (216°-248° C.), in the twelfth rectification ; it is also contained in small
quantity in the fractions a little below and above those points.

In a case like the present, where the chief means of separation was distilla-
tion, it was, of course, impossible to obtain the 18 and 20 carbon bases perfectly
free from each other, and in bodies of so high an atomic weight, it was useless to
attempt to prove their constitution by analyses of the bases themselves, as they
only differ by :2 of a per cent. in the carbon, and when freed from those of the
picoline series are extremely difficult to burn.

As no doubt exists of the constitution of the double salt formed with chloride
of platinum, and as the salts of the two bases differ in the amount of carbon they
contain by two per cent., and, moreover, are readily obtained pure, I availed my-
self of them to determine the fact of the existence of the two homologous bases
in the fractions.

The properties of chinoline and lepidine approach so nearly, that one descrip-
tion will serve for both, less distinction being observable between them than is
found to occur with a difference of C, H, in the other volatile bases.

It is remarkable to find bases bates at such extremely high temperatures
give such well crystallized salts as those of chinoline and lepidine; even the
portion boiling at 520° F. (271° C.) affords a fine platinum salt, almost in-
soluble in water, and without the slightest tendency to assume a resinous or oily
condition, as the salts obtained from bases with such high boiling points are so
liable to do.

As chinoline has so long been known, although not in a state of purity, I was
satisfied, for the purposes of the present investigation, with determining the com-
position of its platinum salt by the following analyses :—

( 10-325 grains of platinochloride of chinoline boiling between 410° and 420° F. (210°
215° C.), tenth rectification, gave

I 12:090 ... carbonic acid and
Tale 2060) sau, | water.
4:280 ... platinochloride of chinoline gave
1:260 ... platinum.
3°530 grains of platinochloride of chinoline gave
II.
1:045 =~... ~— platinum.
6:560 grains of platinochloride of chinoline gave
TII.< 7°755 ... carbonic acid and
1°550 ~~... ¢) water:
9:900 grains of platinochloride of chinoline gave
IV.< 11:805 ...__—_ carbonic acid and
2300 ... water.

3:265 grains of platinochloride of chinoline boiling between 420° and 430° F, (216°
221° C.), eleventh rectification, gave
‘960 ... platinum.

7 OE ee ——

PRODUCED BY DISTILLATION OF CINCHONINE. 321

I. II. III. IV. V. Calculation.
TT
Carbon, 31:93 i 32°24 32°52 an 32°22 Crow KOs
Hydrogen, 3°09 oe 2°62 2°58 Ae 2°39 Ee 8
Nitrogen, ate ae = a id 4:18 N 14
Chlorine, bee 2 ae ih re 31°77 Cl; 106-5
Platinum, 29°44 29-60 ee fe 29°40 29°44 Pt 98-7
100-00 335°2

Lepidine.—After repeated rectifications it was found that the fraction boiling
about 510° contained another base, to which I give the name of lepidine.* It was
only, however, when the rectifications had been very frequently repeated, that it
was obtained pure. My reason for giving a new name to the base containing
twenty equivalents of carbon, and retaining that of chinoline for the other was,
that C,, H, N, is almost universally received as the formula of the latter. It has
been said that the positions of the bases in the fractions greatly alter as the
rectifications proceed. This is nowhere more strikingly illustrated than with
lepidine, which in the eighth rectification was met with as low down as 420° F.
(216° C.). By fractional crystallization, without heat, a crop was obtained, which
yielded the annexed numbers :—

{ 5°905 grains of platinum salt gave

1685 ... platinum.
Experiment. Theory.
28°53 28°27

But this salt formed only a small portion of the original fraction, for upon further
evaporation crystals were obtained, which the subjoined platinum determination
proved to consist of platinochloride of chinoline,—

6:345 grains of platinochloride of chinoline gave
1885 ... platinum.
or per cent. 29°71.
Experiment. Theory (Chinoline.)

29-71 29°44

The real boiling point of lepidine is probably as high as 500° F. (260° C.), or
even a little higher, and after four more rectifications, no sign of it could be found
in the fraction at 420° F., and the nearest approach to a pure base was obtained
at 510° F. (265° C.). But by so many distillations, at such an elevated tempera-
ture, it becomes slightly decomposed, a little pyrrol and carbonate of ammonia
being formed; this in addition to the incombustibility of the fluid rendered its
purification and analysis difficult. Fortunately, however, the same remark does
not apply to its salts.

3°615 grains of lepidine gave

11:040 ... of carbonic acid and
2140 ... of water.

* From demos.

VOL. XXI. PART Il. 4R

322 MR C. G. WILLIAMS ON THE VOLATILE BASES
Experiment. Calculation.
—- oy. eF«yXwX—Xw=
Carbon, ; : 83°29 83°91 G35 41120
Hydrogen, . : 6:57 6:29 Ee
Nitrogen, : : 10°15 9°80 N 14
100-00 143

The above analysis, as regards the carbon, would be useless as evidence of the
existence of lepidine, because, as has been said, the 18 and 20 carbon formule
only cause a difference of ‘2 of a per cent., but the hydrogen is so much
higher in lepidine, that some slight judgment may be formed from the numbers
obtained.

The platinum salt of lepidine contains two per cent. more carbon, and more
than one per cent. less platinum than chinoline, and the analysis of that obtained
from the fraction boiling between 510° and 520° F. (265°, 271° C.), which had
been rectified no less than twelve times, gave the following result,—

10-265 grains of platinochloride of lepidine gave
I.¢ 12:740 ... carbonic acid, and

2-720 =... ~~ water.
3°335 grains of platinochloride of lepidine gave
i 7 ,
‘940 .., platinum.
9-125 grains of platinochloride of lepidine gave
IIJ.< 11:°455 ~... carbonic acid, and
2:430 ... water.
IV 3'330 grains of platinochloride of lepidine gave
‘ 935 ... platinum.
Experiment. Calculation.
nn
: I. & II. Ill. & IV.
Carbon, : ‘ : 33°85 34:23 34°36 Ch 120
Hydrogen, A : : 2:94 2°96 2:86 H,, 10
Nitrogen, : : : re se 4:01 N 14
Chlorine, , ; : Sue ce 30°50 Cl, 106°5
Platinum, : ; : 28°18 28°08 28-27 Pt 98-7
100-00 349-2

As a further confirmation of the constitution of lepidine, the density of its
vapour was ascertained with the following result,—

Temperature of balance case, , : : : 4 : 58° Fah.
2 vapour § ‘ 4 - . : ‘ . 551° «
Excess of weight of balloon and vapour over balloon and air, . 10-050 grains.
Capacity of balloon, : d . : : : : . 325°5 cub. Cent.
Barometer, ; “ : : : 5 : ‘ : . 29°852 inches,
Residual air, . : : : : ; : : : : 0-
Theoretical Density of Vapour. Experiment.
Coben 4 vols.
4:94 5:14

Mitrate of Lepidine.—When the fraction boiling from 500° to 510° F. (260-
266° C.) is dissolved in nitric acid of moderate strength, a solution of a pale red
colour is obtained, which, on evaporation, yields a deep brownish-red deliquescent

_
‘

‘

PRODUCED BY DISTILLATION OF CINCHONINE. 323

crystalline mass, which on solution in water and re-evaporation becomes lighter
in colour. The nitrate in this state cannot be obtained in the form of a dry or
pulverulent salt, in consequence of the presence of an impurity which renders it
readily fusible at 212°. But ifthe salt is pressed repeatedly between folds of
blotting paper, and then crystallized from alcohol, fine hard prisms are obtained,
quite infusible at 212°, and without the slightest tendency to deliquesce. As a
little colouring matter was still retained, rendering the salt yellow, the crystals
were pulverized and washed with ether, in which they were nearly insoluble; the
purified salt gave, on combustion, the numbers annexed. It should be stated, that
the first analysis was made upon a mixture of two crops, the second of which
was obtained by evaporating the mother liquor of the first, the second and third
analyses were made upon the first crop of crystals.

6:840 grains of nitrate of lepidine (mixture of two crops of crystals) gave
I, < 14-470 carbonic acid and
3°035 water.

6°855 grains of nitrate of lepidine (first crop of crystals) gave
II. < 14:680 carbonic acid, and
3025 water.

6-340 grains of nitrate of lepidine (first crop of crystals) gave
III.< 18°540 carbonic acid, and
| 2:845 water,
Experiment. Calculation.
I. Il. III. Mean.

Carbon, 57°69 58°40 58°24 58:11 58°25 Cr 120
Hydrogen, . 493 4:90 4:98 4-93 486 H, 10
Nitrogen, ee a: Ae a 13-59 N, 28
Oxygen, 23°30 O, 48

100:00 206

Hydrochlorate of Lepidine.—This salt is obtainable without difficulty in small
white needles. The reason that former experimenters found so much time and
trouble necessary to obtain crystals, was the presence of the more volatile bases,
which, strange to say, yield crystalline salts with far greater difficulty than either
chinoline or lepidine. The crystals of hydrochlorate of lepidine are quite infusible
at 212°. An analysis gave the following result :-—

7630 grains of hydrochlorate of lepidine, dried at 212°, gave
6:060 chloride of silver.

giving a percentage of 19°64 of chlorine, being exactly the quantity required for
the hydrochlorate of lepidine, as will appear from the annexed comparison with
the theoretical percentages.

Experiment. Calculation.
—[—[—[—__—_———
Carbon, ‘ arte 66°85 Ce 120
Hydrogen, . 5 ane 5°57 Ho 10
Nitrogen, ao 7°80 N 14
Chlorine, 19°65 19-78 Cl 35°5
100-00 179°5

324 MR C. G. WILLIAMS ON THE VOLATILE BASES

Bichromate of Lepidine.—This extremely beautiful salt is easily obtained by
adding an excess of a rather dilute solution of chromic acid to lepidine. For the
first few seconds the chromate, on touching with a glass-rod, appears resinous,
but the instant it is stirred the salt becomes gritty and crystalline. On filtering
off the crystalline powder obtained in this manner, and dissolving it in hot water,
the salt crystallizes out on cooling, in needles nearly an inch long, extremely
brilliant, and of a rich golden yellow. The mother liquors, on evaporation, yield
afresh crop. It does not appear to be at all decomposed by moderate boiling
with excess of dilute chromic acid. It decomposes at no very elevated tempera-
ture, and if suddenly heated to 212° when slightly damp, it becomes converted into
a mixture of green oxide of chromium and charcoal. On one occasion, this took
place with a very curious phenomenon. About four grains in powder having been
placed on a water-glass, on the upper shelf of the water-bath, it was not observed
for about one hour, during which time it had become converted into a mass of
flattened rods, reaching to the top of the water-bath, a distance of about 14 inches,
and had turned down again on all sides, in a manner which gave the whole much
the appearance of the capital of a Corinthian column. In general, however, it
may be dried at 212° with perfect safety ; if retained more than an hour or two in
the bath it begins to turn slightly brown, but experiences no further change during
five hours’ exposure. On ignition, the salt behaves like the bichromate of ammonia
and the chromate of strychnine, inasmuch as it leaves pure green oxide of chro-
mium. This fact enables the constitution of the salt to be determined with accu-
racy. The following experiments were made upon three different specimens.

4-105 grains of bichromate lepidine, dried at 212°, gave

" { 1:260 ... — green oxide of chromium.
6-290 grains of bichromate lepidine, dried at 212° until slightly brown, gave
II. : : ,
1:940 ... green oxide of chromium.
IIT 6-850 grains of bichromate lepidine, dried at 212° for five hours, gave
*) 2:120 .., — green oxide of chromium.
7°315 grains of bichromate lepidine gave
IV.< 12°620 ... carbonic acid, and
2605 2) 4) water,
Experiment. Calculation.
SS ——_—_—_—_—_—_—
I. Il. II. IV.
Carbon, ; es NC on | MeAT206 47°36 Cr 120-0
Hydrogen, . ane =e oes 3°89 3°95 ela 10-0
Nitrogen, . ote sais Sts a7 5°52 N 14:0
Chromium, . Qt] 92L28 “WRS5d | '6.. 21-07 Cr, 53°4
Oxygen, ; “ie i Bie aa 22:10 O, 56:0
100-00 253-4

Consequently the formula, is
CghowN, 2.010r 0; -. 110;

The salt analysed agrees therefore with the bichromate of ammonia in only con-
taining one atom of water.

'

PRODUCED BY DISTILLATION OF CINCHONINE. 325

Hydriodate of Amyl-Lepidine.—On treating lepidine with iodide of amyl in a
pressure-tube at 212° for some hours, a finely crystallized salt is obtained, rather
sparingly soluble in water ; it was analysed by determining the percentage of iodine.

8-685 grains of hydriodate of amyl-lepidine gave
6025 ... iodide of silver.

corresponding to 37°49 per cent. ; hydriodate of amyl-lepidine requires the follow-
ing numbers :—

Experiment. Calculation.
a
Carbon, . , Rie 52°79 (OF, 180
Hydrogen, . : ae 5°87 Ey, 20
Nitrogen,- . j at 4:10 N 14
Todine, : : 37°49 37.24 I 127
100-00 341

Aydriodate of Methyl-Lepidine is a finely crystallized body, but its history,
and that of the analogous salt C, H, below it, will be given in another paper, in
which the leukoline of Hormann will be compared with pure chinoline.

The experiments detailed prove, therefore, that cinchonine, by distillation with
potash, yields pyrrol, pyridine, picoline, lutidine, collidine, chinoline, and lepidine,
a result which indicates a total breaking up of the cinchonine, and of this the ap-
pearance of pyrrol may be considered as a further confirmation, my experiments
having shewn that that substance is, in general, characteristic of the complex
decomposition of nitrogenous substances.

When feathers, wool, or hair, are distilled perv se, sufficient pyrrol is evolved to

’ give a reaction instantly, with deal wood moistened with hydrochloric acid, and

as the experiment can be made in a test-tube, it serves very well for lecture illustra-
tion. Feathers yield a very large quantity of bases and carbonate of ammonia
when distilled. The former appear, from my experiments (which, as yet, have only
been on a very small scale), to contain some different from those at present known.
Pyrrol possesses perhaps, as high an interest as any basic substance obtained by
destructive distillation ; and it is singular, that most nitrogenized bodies, when
burnt with soda-lime, by Witt and VarreEnTRArP’s process for determining the
nitrogen, evolve pyrrol, which, passing through the acid in the bulbs, may be recog-
nised by the reaction with deal wood and hydrochloric acid. Among the bodies
tried in this manner, and found to give unequivocal reactions, may be mentioned,
guanos, dried turnips, oil-cake, hay, and para grass. Whether these facts prove a
loss of nitrogen, is at present doubtful, but the question will probably be solved,
when Dr ANnpERson’s researches on the pyrrol series of bases from Dippel’s oil are
completed. |

VOL. XXI. PART II. 4s

326 MR C, G. WILLIAMS ON DISTILLATION OF CINCHONINE.

The following is a list of the substances analysed in this paper,—

Platinum salt of pyridine, Cig es > CE Beck
picoline, Cha NH CEO: Ce
Timtidine, m1 : Ciastle JON,
Platinum salt of ipl ; Cobo, BC, Pricey
sal tak methy1-lutidine, Ciptagen> a OL PEGI
Si collidine, Ce Hii) Boch Pre.
‘ chinoline, Ci, HIN, Cl, Pre,
Leptin . Cie N,
Platinum salt lepidine, OF = Fe es U8) FE 8 0
Hydrochlorate lepidine, - Cea: D> oe Cl
Nitrate lepidine, Cy a SN, DOP HS
Bichromate lepidine, F Cog Bie Nae Cr 0,, HO
Hydriodate amy]-lepidine, big Ne EUL

(R327 1)

XXI.—On the Extent to which the received Theory of Vision requires us to

regard the Eye as a Camera Obscura. By Grorcr Witson, M.D., F.R.S.E.,
Director of the Industrial Museum of Scotland.

(Read 2d April 1855.)

In the course of those researches on Colour-Blindness, which, at intervals, I
have recently been engaged in prosecuting, I have encountered some phenomena
connected with normal vision, which I am desirous to submit to the considera-
tion of the Society. Those phenomena I have already in part detailed, in the
account of the researches referred to,* and I shall not, accordingly, repeat the
description of them here, to a greater extent than is essential to rendering in-
telligible the question which I wish to submit for discussion.

I venture to assume, that without adducing a lengthened series of authorities,
I may take for granted, that, on the received theory of vision, the eye of man, as
well as that of most of the lower animals, is regarded as essentially realizing,
during the performance of its function of sight, the condition of a darkened
chamber, or camera obscura. In more precise words: the theory in question
teaches, that those rays of light, which reach the eye from the objects which
they render visible, and entering at its front traverse all its transparent humours
and membranes, last of all pierce the retina, and after making that impression
upon it which is supposed to be the most important physical element of vision,
are stopped, or absorbed by the dark pigment lining the choroid coat, and suffer
extinction as visible rays. The dark surface of the choroid is thus held to
abolish all the light which reaches it, so that none of the luminous rays return
through the retina, or retrace their course across the chamber of the eye.

The doctrine thus taught appears, in the present state of our knowledge, to be
in great part beyond dispute. It may suffice on this point to notice :—

(1.) That no other use has been assigned, or readily suggests itself, for the
existence of a dark lining to the deepest membrane of the eye on. which light
falls, than the one referred to.

(2.) That, as theory indicates, and the experience of our artificial camerze ob-
scuree teaches, the darker all their internal walls are, the more marked and
sharply defined is the picture which light produces upon the screen at the back
of the camera.

(3.) That, apart from the sharpness of definition secured by the contrast be-
tween the darkness of the ground, and the brightness of the picture in all ca-

* Researches on Colour-Blindness. Sutherland and Knox, Edinburgh, 1855.
VOL. XXI. PART II. 47

328 DR GEORGE WILSON ON THE

mere, there is a further necessity for a black lining to the living camera, or eye-
chamber; for were that lining wanting, and the internal surface of the choroid
highly reflective, the same ray of light might return many times across the cham-
ber of the eye, producing multiple images of single objects on the retina, exhaust-
ing its sensibility, and confusing vision.

(4.) That this, moreover, is no hypothetical case, is held to be demonstrated
by the experience of the Albinoes of our race, in whom the pigment of the choroid
is wanting, and who see with pain and effort, unless by dim light.

The views stated above have till very recently been universally held by phy-
siologists and natural philosophers; in proof of which it may suffice to quote the
following passage from the Elements of Physiology of Professor MiLLEer, who has
written very fully on the theory of vision, and is one of the highest living autho-
rities among physiologists on this subject.

“« The interior of the eye, namely, the posterior surface of the iris and ciliary
processes, and the inner surface of the choroid, immediately external to the retina
itself, is coated with black pigment, which has the same effect as the black colour
given to the inner surface of the walls of optical instruments. It absorbs any
rays of light which may be reflected within the eye, and prevents their being
thrown again upon the retina, so as to interfere with the distinctness of the
images there formed. This is the use of the pigment on the posterior surface of
the iris and ciliary processes. But the coating of the outer surface of the retina
by the pigment of the choroid is also important in the same respect; for the re-
tina is very transparent, and if the surface behind it were not of a dark colour,
but capable of reflecting the light, the luminous rays which had already acted on
the retina would be reflected back again through it, and would fall upon other
parts of the same membrane, the consequence of which would be, not merely
dazzling from the excessive action of light, but also indistinctness of the images.
Animals in which the choroid is destitute of pigment, and human Albinoes suffer
in this way ; they are dazzled by daylight, and see best by twilight.’’*

Thus far, then, there does not appear to be room for two opinions concerning
the internal darkness of the human eye being a condition of perfect sight. But
recent discoveries require us to look at the theory of vision from an opposite
point of view. It is now beyond question, that even in the darkest human eye,
there is reflection through or across its chamber, from the surface of the retina,
as well as from that of the choroid; and the observation is a very old one, that ina
large number of animals, a part, and sometimes the whole of the retinal surface is
covered, or replaced} by a reflector rivalling in brilliancy a sheet of polished silver.

* MixieEr’s Elements of Physiology, vol. i, p. 1133. 1842. Translated by Baty.
t I do not intend by the words “ covered” or “ replaced,” to imply any opinion on the anatomical
relation of the tapetwm lucidum to the other structures of the eye. In an optical point of view, it is

the substitution of a highly reflective, for a partially absorptive surface. 2

————eo

EYE AS A CAMERA OBSCURA. 329

That the eyes of living men and women emitted light, and shone like those of
the cat, had been occasionally noticed and recorded from an early time, but the
phenomenon was supposed to be an exceptional, and indeed very rare one, and
was either credulously magnified into a highly marvellous occurrence, or despised
as of questionable accuracy, and of little real significance. In (or about) 1847,
however, Mr Cummrine, an English medical practitioner, pointed out that the phe-
nomenon in question might be witnessed in every human eye, if looked for in the
right way; and a little later and independently, Briickr made the same discovery
in Germany, through the curious circumstance, that occasionally when looking
through his spectacles, at the face of another, he saw his neighbour’s eye glare like
a cat’s.

In 1851, the accomplished physiologist and natural philosopher of Koenigs-
berg, HeLMHoLtz, showed how the observation which Bricker had made accident-
ally, might be repeated at will; and carrying out the principle thus established,
constructed an eye-speculum which soon proved a most valuable addition to the
diagnostic apparatus of the oculist. Other eye-specula or ophthalmoscopes were
devised or improved by Ruts and Cocctus of Leipsic, ANacNnostakis of Athens,
and the English opticians, and are now in use in the hospitals of this country
and the continent. It will be sufficient for me, therefore, to give in a note, the
names of some of the chief works from which those to whom the subject is new
may obtain information regarding eye-specula; especially as no more complex
instrument than a fragment of polished glass, or of perforated polished metal is
required to show that light is reflected from the bottom of the eye; and even this
is only needed to facilitate the observation ; for by following Mr Cumminea’s direc-
tions the fundamental phenomenon may be witnessed without the employment
of any reflector.*

The demonstrability of the proposition, that the eye is not a camera obscura,

* Cummine’s observations are contained in Medico-Chir. Trans., Lond., vol. xxix., p. 283;
Bricke’s, in Mixuer’s Archiv., 1847, p. 225.

Hetmuorrz’s description of his speculum occurs in a little work, entitled, “ Beschreibung emes.
Augen-Spiegels zur Untersuchung der Netzhaut in lebenden Auge. Berlin, 1851.” An excellent
abstract of this paper by Dr W. R. Sanpers, accompanied by comments of his own, will be found in
the Edinburgh Monthly Journal of Medical Science, July 1852, p.40. Iam indebted to this gentle-
man for my knowledge of Hutmnottz’s instrument, and for the opportunity of using it.

The eye-specula of Ruers and Coccrvs, as well as of Hrtmuotrz and others, are described in a
work, entitled, “ Bildliche Darstellung der Krankheiten des Menschlichen Auges, von Dr C. G. T.
Ruere; 1 and 2 Lieferung: Leipzig, 1854.’’ Professor Ruzte’s beautiful work contains a series of
coloured drawings, representing the internal structures of the eye, as seen under the speculum.

Since this paper was read to the Society, a valuable communication on the medical employment
of eye-specula has appeared in the British and Foreign Medico-Chir. Review for April 1855 (p. 501 )
It is entitled, “‘ On the Means of Diagnosing the Internal Diseases of the Hye. By C. Bapsr, M.D.,
and Branspy Rozerts, Esq., Resident Medical Officer, Royal London Ophthalmic Hospital, Moor-
fields,” and contains the fullest and most recent account of eye-specula accessible to English readers,
with a record of observations made on healthy and diseased eyes. From this paper, I have borrowed
the use of the word Ophthalmoscope, used occasionally in the text.

330 DR GEORGE WILSON ON THE

depends upon the fact, that when rays of light enter the eye, and fall upon its
back wall, as many of them as are reflected from the retina, or from the choroid
behind it, will exactly retrace their course, and pass out through the pupil to the
luminous body or illuminated object from which they came. Thus the diverging
rays of a gas-flame are converged by the refracting media of the eye, to a focus
upon the retina, where they unite to produce a picture, and thereafter in great
part traverse that membrane and fall upon the choroid. If from either of these
membranes rays are reflected (and for the sake of simplicity, we may, for the
present, limit ourslvees to the retina, which is the more powerful refiector of the
two), they will follow in a reversed direction, the very course which they took in
reaching that membrane, and return to the gas-flame, producing there an image of
the picture on the retina, so that the reflected image of the flame is placed upon,
and coincides in size and position with the actual flame.* To see, therefore, into
the deeper chambers of a living eye, we must arrange matters so that we can look
along the straight line of the reflected rays, without intercepting the light from
which they originally came. The earlier observations of CummMING were made
without any special arrangement to prevent such interception of light; they were
rendered possible by the circumstance, that certain of the rays returning from
the bottom of the eye undergo irregular reflection, and diverge from the direct
line which theoretically all should follow, so that if the observer keeps a very
little to the side of this line, standing almost between the light and the observed
eye on which it is falling, he catches a sufficient number of the irregular rays to
see into the interior of the eye from which they come.

It was doubtless the accidental realization of this condition of matters, that
led to the occasional observation, from very early times, of luminous emissions
from human eyes;+ but even when the necessary conditions are fully realized,
the illumination is so imperfect that the results are unsatisfactory. By the em-
ployment, however, of a plane transparent reflector, such as a plate of polished
glass, or of a plane or concave mirror, perforated or rendered transparent at the
centre, the source of the light may be placed at an angle, both to the observing and ©
the observed eye, so as to enable the former to receive directly much of the light
reflected from the latter. The following diagram will show how this occurs in ~
the case of the transparent reflector, which is the essential part of HELMHOLTz’s
instrument; the opaque perforated reflector forming the basis of that of Coccrus;
the whole reflection is supposed to take place from the surface of the retina.

* See Hetmuottz’s ‘‘ Beschreibung eines Augen-Spiegels,” &c.; and Dr Sanpers’ excellent ab- —
stract of this Memoir, from which I have borrowed in the text; also Rurrz’s Preliminary Chapters
in his Bildliche Darstellung.

i On the Luminousness Observed in the Eyes of Human Beings. Edinburgh Phil. Journal,
1827, p. 164.

EYE AS A CAMERA OBSCURA. 331

« Let A bea flame, whose rays are caught at an angle on a glass-plate ©, the
rays will be thrown along the line CD, into the eye D, which will see an image of
the flame along the line DB; but the rays reflected from
the retina passing out in the same line DC, will again
meet the plate C; they will be in part turned towards
A, but in part also will traverse the glass-plate C, and go
to form a picture at B of the image on the retina; but an
eye G, placed behind the glass-plate and on the line CB,
will meet these reflected rays, and will consequently see t
the posterior chamber of the eye D illuminated.”*

The experiment is thus made:—“ In a dark room,
with a single flame at the side of the experimenters,
and on a level with their eyes, the person whose eye
is to be observed holds a piece of glass (a microscope
glass slip), so as to catch the image of the flame on
it; he then, by inclining the glass, brings the image of
the flame opposite the pupil of the observer’s eye; the
latter will then see the pupil of the observed eye lumi-
nous, of a reddish-yellow bright colour. . . . . A
person may also see one of his own pupils luminous: standing before a looking-
glass, and seeing the image of the flame in the reflector with his right eye, let him
bring this image opposite the pupil of the left eye in the looking-glass; the left
eye will then perceive the right pupil in the mirror luminous.” +

The very simple arrangement which has been described, is all that is required
to develop the phenomena to which I wish to refer; and the speculum differs from
it only by employing four glass-plates instead of one, to increase the illumination
of the observed eye, and adding a double concave glass, to increase the distinct-
ness of the image on the observer's eye.

The reflector of Coccius, plane or better concave, is an ordinary glass mirror,
with the silvering on the back scraped off, so as to leave in the centre a small
transparent circular spot, or with a hole bored through the centre of the entire
mirror. Through this transparent spot or aperture the observer looks from the
unsilvered side, directing the light reflected from the opposite surface into the
observed eye, while the pupil of the latter and of his own eye are in a straight line.

The mirror is round, with a diameter of about two and a half inches; and a
focal distance of about six inches. The aperture in the centre has a diameter of
about two lines. The arrangement of the lamp is substantially the same as when
HELMHOLTz’s speculum is used, and the mode of action, so far as illumination of
the observed eye is concerned, similar.

With either of the arrangements described, the interior of any eye can be

* Edinburgh Monthly Med. Journal, July 1852, p. 41. t Op. cit., p. 42.
VOL. XXI, PART Il. 4u

332 DR GEORGE WILSON ON THE

readily examined, and I see no reason to doubt that photographic images of
the retina and choroid may be obtained and preserved on collodionised or other
actino-sensitive surfaces.

By means of such Ophthalmoscopes, in the hands of Hretmuo.tz, Cocctus,
RueEtE, and others, it has been placed beyond question, that much of the light
which enters the human eye is reflected from the anterior surface, or from some
depth within the layers, of the retina, without entirely traversing that membrane,
or reaching the choroid, so as to be subjected to the absorptive action of its dark
pigment. So far, therefore, as the accepted theory of vision demands that the
light which has reached the retina shall not return across the chamber of the
eye, it must be abandoned; and the evils which are supposed to be inseparable
from such cross lights, or luminous reverberations, are encountered at every mo-
ment by every eye, whether animal or human, at least in the case of the Verte-
brata, which is engaged in the exercise of vision; yet it is vision so marred and
obstructed which we are in the habit of calling perfect. We must plainly mend
our theory, or our language, for they are inconsistent with each other.

Before seeking to determine which must be altered, it is important to notice,
that, according to the views of certain recent writers on the eye, among whom I may
specially name KoLLikEer and Henry Miter, the German physiologists, it is not
the anterior part or face of the retina, but its deeper portions which are optically
sensific ; and light must penetrate to them before the sensation of vision can be ex-
perienced. If this view be well founded, then we may be led to the somewhat start-
ling conclusion, that much of the light which is reflected from the retina, at the best
contributes nothing to vision whilst within the eye, even if we deny that it posi-
tively obstructs it. And if we suppose, with the older authorities, that all the light
which reaches the retina penetrates it sufficiently deeply to excite luminous sen-
sation, then it is manifest that so far as that portion which is reflected outwards
is concerned, the dark surface of the choroid is quite superfluous.*

* I am indebted to my pupil, Mr James Warprop, an accomplished theologian and naturalist,
for an abstract of the views of K6Liixer and H. Miitter. Their opinions are contained in KOriiKcer’s
Micr. Anatomie, B. 2, Zweite Halfte 606-720. See also H. Miitter’s Remarks on the Structure
and Function of the Retina, translated in the Quarterly Journal of Mier. Science, July 1853, pp.
269-273. Without entering into the minute discussion of anatomical questions which I am not
competent to decide, it may be noticed, that both the skilful observers referred to, agree in denying
to the fibres or expansion of the optic nerve, the function of perceiving “ objective light.” This fune-
tion belongs, according to them, to the deepest of the five layers of which they regard the retina of
vertebrate animals as composed. This layer, which is immediately in front of the choroid, is. thus
described by K6iL1xeR :—‘ The external or bacillar layer consists of the ‘ rods and bulbs’ (bacilli
et coni), whose ends evenly terminated, form a sort of mosaic pavement towards the black pigment,
and which internally are continued by fibres (MiitiEr’s fibres) through the three succeeding retinal
layers, to abut abruptly, and with radiating terminations on the external aspect of the fifth layer,
which, however, they do not penetrate.”’ This fifth layer is a very delicate membrane, investing the
entire internal or anterior aspect of the retina.

Accepting this description as well-founded (and it has received the approbation of the majority of
recent physiologists), it appears that light must more or less traverse the anterior layers of the retina,
till it reaches the ‘“‘ rods and bulbs,” with their connecting radiating fibres, before it can excite a

EYE AS A CAMERA OBSCURA. 333

- On either view, we must qualify the statement that the eye is a camera ob-
scura; but before attempting such qualification, it is necessary to consider the
reflection of light from the choroid behind the retina. As the latter membrane
during life is quite transparent, and is traversed throughout its entire thickness
by many of the rays which fall upon it, these must, in part, be reflected from the
choroid which receives them, unless we impute to this membrane a power of
absolute absorption, so far as light is concerned. Something little short of such
a power is habitually attributed to the choroid, and not unnaturally. The dark-
ness of the pupil, even in the lightest normal eye, is by most persons referred to
the dark background against which we are supposed to see it, as its cause. The
pink pupil of the Albino is in the same way connected with the crimson choroid
at the bottom of his eye; and these views are supposed to be justified by the
appearances in the dead organ, where a black or brown pigment is found coating
the one choroid, and absent from the other. It has thus been generally inferred,
that the dark choroid of the perfect eye does not sensibly reflect light, whatever
may be the case with the retina,—a conclusion certainly not warranted by dis-
section; for, on the one hand, the choroid after death appears darker and less
reflective of light than during life, in consequence of the bloodvessels of which it
so largely consists becoming emptied of blood; and, on the other, Jounn Hunter
has long ago permanently illustrated in his great museum, that the pigment of
the choroid “in the human species is,” to use his own words, “ of all the differ-
ent shades between black and almost white,” * and, as he also states, is generally
lightest in colour at the bottom of the eye,} where, of course, its position best
enables it to act as a reflector. Excluding the white choroid, which belongs only
to the abnormal albino, there is plainly room in the other pale tints for much
reflection.

But it is needless to accumulate arguments in proof that the choroid must
reflect light, seeing that by means of the ophthalmoscope, every one may satisfy
himself that this membrane certainly does. HeLMHourz referred to his instru-
ment chiefly as a retina-speculum, and as such it was described by Dr SanprErs,
writing for practical medical men, to whom the retina is much more an object of
interest, as liable to disease, than the choroid. The latter membrane, however,
was plainly within the reach of the speculum; and later observers have carefully
depicted and described its appearance under their ophthalmoscopes. Ruets and

luminous sensation, It must, however, in part be reflected from those anterior layers before reaching
the deepest one. The internal or anterior surface of the bacillary layer is further described, as
smooth and brilliant, the * bacilli and coni’” appearing like the polished surfaces of crystals, so that
they reflect light powerfully, and the greater number of the rays which are returned from the retina,
| have probably been reflected from its deeper layers, whilst a portion has been thrown back from the
anterior layers, without contributing to the perception of light. The only point, however, which I
‘am much concerned to urge is, that the retina, as a whole, reflects much of the light which reaches it.
ees cin on certain parts of the Animal Economy. By Joun Huwnver, F.R.S., vol. iv.,
| p. 278.
+ Catalogue of Museum, R. C. S., Lond., vol. iii., p. 133.

334 DR GEORGE WILSON ON THE

Coccius specially refer to the varying colours of the “ background,” as they term
it, of the eye, z.¢., the retina and choroid taken together, which is never black,
nor even brown, but bright red when the pigmentum nigrum is scanty, yellowish-
red when it is mere abundant, and brownish-red when it is largely present.
Coloured drawings are given in illustration of these statements.*

Messrs BapEr and Rosrrts describe the choroid as exhibiting under the oph-
thalmoscope, “a brilliant red surface,’’ and state more particularly, that this
membrane is “covered by a very tender, pointed, grayish-brown layer of pigment,
giving the appearance of an uniform red surface;” adding that “a comparison of
many healthy eyes of different ages is needed for the purpose of having a correct
idea of the normal red of the choroid.” +

In the comparatively few observations which I have been able to make on the
appearance of the choroid through HELMHoLTz’s speculum, it has appeared yellow-
ish-red, and it is thus represented in RuetE’s drawings. Some allowance must
doubtless be made for the quality of the light employed, which is always from an
artificial source when ophthalmoscopes are used ; but after allowing for this, it ap-
pears that even minute medical observers are content to describe the choroid as
uniformly red or yellowish-red, and that in the darkest human eyes it deepens only
by a degree or two into brownish-red. In short, whereas, were the choroid so
powerfully absorbent of light as it is generally supposed to be, it should more or
less resemble, as seen through the retina, polished ebony or walnut wood, it re-
flects so much red light, that one who saw it for the first time, would probably
at once credit the statement, that he was gazing on the choroid, not of a normal,
but of an Albino eye.

The choroid thus, as well as the retina, is a reflector of light, and deprives
the eye of the character of a camera obscura; nor can it have escaped the notice
of the able Germans to whom we are indebted for the first full exposition of this
truth, that it necessitates an alteration in the current theory of vision. Yet so
far as I am aware, no alteration of that theory has hitherto been proposed by any
writer; nor are the facts which demand a change as yet familiar to opticians or
natural philosophers who are not physiologists. t

The reluctance which has thus been shown to include in an altered theory of
vision the occurrence of deep reflection of light within the eye, appears to be
based upon three considerations. The 1sé¢, that in the eyes of human Albi-

* Bildliche Darstellung, Tab. II. + Brit. and For. Medico-Chir. Rev., April 1855, p. 509.

t+ Since reading this paper to the Society, I have learned from Mr Warpropr’s Abstract of Koxx1-
KER’S paper, that some of the latter’s countrymen suppose that the bacillar layer of the retina reflects
light on the optic fibres, and thus enhances vision, K06xniiKer’s words are “ This bacillar layer does
not act as a catoptrical apparatus, as Hannover, Briicke, and Hetmuotrz think, for reflecting the
light back to the optic fibres, but as a true nervous apparatus for itself receiving the impression.”—
(Mier. Anat., B. ii, Zweite Halfte, p. 691.) Even, however, were the view objected to by Korner
well-founded, it would not dispose of the question discussed in this paper, for the main direction of
the light reflected from the bacillar layer of the retina must be forwards and ontwards,'so as to illu-
minate more or less the entire chamber of the eye.

EYE AS A CAMERA OBSCURA. 335

noes, where the pigment of the choroid is altogether absent, and choroidal reflec-
tion is at a maximum, vision is imperfect, as well as painful. The 2d, that
those animals which have the pigment of the choroid at the bottom of the eye
covered or replaced by a ¢apetum lucidum, or metalline mirror, are impatient of
the sun, and, like albinoes, see comfortably only by faint twilight. The 3d, that
the known laws of luminous reflection make it impossible that vision should be
perfect, if light is free to cross the chamber of the eye in all directions.

Now, to take those objections in order :—1. It is not to be denied that albinoes
of our own race experience great intolerance of bright light; see with difficulty,
unless it is faint; are generally short-sighted; and exhibit, unless in darkness,
a continual tremulous motion of the eyeballs, as if vainly seeking to remove from
the influence of light each dazzled point of the retina on which it falls. But it
appears to have escaped the observation of physiologists, that it is otherwise with
many of the albino varieties which occur among the lower animals. In thinking
over this matter, I called to mind, that in watching in earlier days the habits
of pink-eyed white mice and white rabbits, I detected no appearance of their
vision being less perfect, or exercised with less readiness and pleasure than that
of their dark-eyed brethren; and all to whom I have mentioned this opinion,
familiar with the ways of those animals, have confirmed my conclusion. Nor is it
difficult to explain why animal and human albinism should differ. There are,
in truth, two kinds of albinism, the one showing itself suddenly, or, as it were, per
saltum, in the immediate offspring of parents who are not themselves albinoes;
the other appearing in every individual of a particular race or variety of animals,
and having been transmitted to it as a hereditary peculiarity, which has descended
through hundreds or thousands of generations.

In the lower animals both kinds of albinism are frequent. A white crow,
for example, or a white blackbird (as we are compelled to call it), is known occa-
sionally to make his appearance among his darker brethren, although unques-
tionably himself of sable lineage; but a permanent albino variety of either bird
is not known. In the mouse, on the other hand, the rat, the rabbit, and a few
other animals, albinism has become permanent in certain varieties, probably
assisted in some by the interference of man in mating the animals. The ferret,
moreover, appears to be a natural variety of permanent albinism.

The albinoes of our own race are all, so far as I am aware, accidental, or per-
haps it would be better to say, incidental or sporadic cases. The older writers,
indeed, acknowledged a distinct race of Leucaethiopes, or White Ethiopians, and
a modern tradition, still sacred among travelling exhibitors, ranks all European
Albinoes among Circassians. There is probably some foundation for both opi-
nions; but though albinism is certainly liable to become hereditary among our-
selves, I am not aware that a case is on record where the parents of a human
albino both displayed this structural peculiarity ; or when it has descended to a

VOL. XXI. PART II. 4x

396 DR GEORGE WILSON ON THE

third generation, that the majority of the parents were albinoes; or that in any
case all the children of a single pair in an albino line exhibited albinism.

The human albinoes, accordingly, to whom our physiologists have referred,
have been generally exceptional or transitional examples of albinism. They
have inherited the highly sensitive retina, and rapidly contractile, irritable iris
of their parents, without a similar legacy of the defensive dark pigment, which
in them protected both organs from the painful impression of excessive light.
With the instincts, accordingly, of their progenitors, and trained by them to pur-
suits like their own, albinoes of our own race have sought to follow all legitimate
callings, and in so doing have soon betrayed their visual infirmity. The imper-
fection of their sight has thus been rendered so manifest, that the hypothetically
perfect vision of others of our race has been assumed to be necessarily the result
of an exactly opposite condition of the eye. On the other hand, in an albino
rabbit of the present day, which has probably had some thousand pink-eyed an-
cestors, the sensibility of the eye has, generations before its time, been adjusted
to the conditions of its existence; for it is certain that the permanence of any
variety among animal species is possible, only provided the variation does not
oustep the limits within which the conservation of life and health is possible.
Hereditary albinism had in prospect the alternative of total blindness, such as
characterises the eyeless fishes, and crustacea of the Mammoth Caves of Kentucky ;
or modified perfect vision, such as it has actually attained to. The modification
which it has suffered is in reality very small, for what has been lost in one direc-
tion by the hereditary Albino eye, has been gained in another; if it sees worse
than a dark eye by meridian light, it sees better by twilight.

The Edinburgh Zoological Gardens afford at present an excellent opportunity
of testing the truth of the opinions I have brought forward. They contain an
albino monkey, an albino rabbit, and several litters of albino rats and mice.
The genealogy of the monkey is not known, but permanent albinism is believed
to be as rare among monkeys as among ourselves, and the individual in the
Gardens exhibits all the peculiarities which characterize human albinoes. I paid
a visit recently to the Gardens, and found my preconceptions more than confirmed.
The monkey, a young adult female, is covered with white hair, which gives her
an aspect of great age; and the overhanging eyebrows, knitted to exclude the
light, add an air of gravity to her venerable look. But she is a gentle creature,
and the offer of a nut or a piece of biscuit, brings her at once from a favourite
shady corner of the cage to the front, where her vision can be readily tested. I
saw her in the afternoon of a bright sunny day, but not in direct sunlight. Dif-
fuse light evidently distressed her; the eyebrows were pulled down to the utmost,
the pupils strongly contracted, the eyeballs in constant oscillation, and the hands
raised in a most human-like way to shade the sight. Frequently one eye was
entirely covered, and the other alone employed in vision; and when anything

EYE AS A CAMERA OBSCURA. 307

specially attracted notice, both eyes were carefully shaded. By a liberal gift of
nuts, however, which occupied for a time both anterior hands, the eyes were left
unshaded, and could be examined. They did not exhibit the signs of extreme al-
_ binism. The pupil was not pink, and the iris was a pale blue.

In strong contrast with the painful vision of the monkey is the quick
sight of a white rabbit, and several white rats and mice, which occupy neigh-
bouring cages. Their fur is milk-white; the skin colourless; the pupil pink or
rather crimson, and large, as compared with that of the monkey.* The ani-
mals were exposed freely to diffuse daylight, but did not shrink from it. No
conspicuous change could be observed in the pupil; there was no oscillation of the
eyeballs, and no closure of the eyelids. They seemed to see as well as their non-
albino neighbours, and to be as little incommoded by daylight, and they were
equally quick in discerning and seizing food. Their keepers, who were aware
of the monkey’s peculiarities of vision, considered the other albino animals
quite as sharp-sighted as their dark-eyed brethren. I would not say so much
myself, or rather I would say it differently. I have no doubt that the albinoes
would see worse in full sunlight, but I have as little doubt that they would see
better in faint twilight.

It cannot then, I think, be questioned, that in those animals which exhibit
the full development of long hereditary albinism, the sensitiveness of the retina to
light has undergone a permanent abatement, whilst the iris has probably altered
also in thickness and contractility. I venture to predict, that if ever an albino
race of men shall be observed or developed, they will prove, after the lapse of
a generation or two from their founders, to have eyes as serviceable as those of
the majority of mankind.+

_* A comparison, also, of pink-eyed with dark-eyed rabbits appeared to show that in diffuse day-
light the average size of the pupil is the same in both; but in direct sunlight the albino pupil is
smaller.

t In truth, in the case even of casual human albinoes, vision, however painful in full daylight, is not
to any marked extent optically imperfect; and in the diffuse or moderate light by which they see cor-
rectly, reflection of its rays within the eye is occurring as certainly as when the light is direct and intense.
I hesitated to urge thus much when the text of this paper was read to the Society, although the
conclusion in question seemed justified by the accounts on record of albinism, especially by Dr Sacus’
very interesting description of his own case and his sister’s. (Hist. Nat. dworuwm LevcarTuiopum auc-
toris ipsius et sororis ejus, 2 G. Sacus, M.D. See also my Researches on Colour-Blindness, p. 102).
But since this paper was read, I had an opportunity, through the kindness of Dr James S1pey, of test-
ing, along with Mr James C. Maxwe tt, the vision of an albino girl, aged 18 or 19. She was born in
India, of Scotch parents, in humble life, and is, in all respects, a well-marked case of albinism. She
sees with much less suffering in this country, than she did in that of her birth, but bright sunlight still
distresses her. There is occasional strabismus of one eye, and both eyes exhibit, under exposure to
light, the tremulous oscillation characteristic of albinism ; not, however, to a very great degree. She
thinks that her vision has improved within the last few years, but how far this is the result merely
of removal from the influence of a tropical sun, it would be difficult to determine.

We found her quick and intelligent. By diffuse daylight, she distmguished the forms of objects
rapidly and accurately. Many trials also were made as to her perception of colowrs, which Mr Max-

308 DR GEORGE WILSON ON THE

However that may be, it is sufficient for my present purpose to point to the
albino animals, whose eyes are totally destitute of pigment, and reflect light from
every point of the surface, both of the retina and the choroid, but, nevertheless,
exercise the faculty of sight in perfection. Their eyes, even when the iris is fully
contracted, remain, in virtue of the transparency of that membrane, camere lucide;:
their possessors cannot render them camere obscure ; and yet they are excellent
organs of vision.

2. If the reasoning pursued in reference to the albino eye be valid, it will serve
also to dispose of the difficulty experienced by some in explaining how vision is
compatible with the presence of a tapetum lucidum in the eyes of many animals,
This tapetum is equivalent to a concave mirror of polished metal, replacing the
pigment of the choroid over a greater or smaller part of its surface, especially at
the deepest or most. posterior portion of the chamber of the eye, so that lying be-
hind the retina, it is more or less directly opposite the pupil, and receives the light
which enters by it. A brilliant reflecting surface of this kind is found in many of
the mammalia, both graminivorous and carnivorous, as the horse, the ox, the
sheep, the cat, the dog. It is present in the eyes of the whale, seal, and other marine
mammalia; and in fishes, such as the shark, in which it is peculiarly brilliant. It
occurs also in certain of the mollusca, as the cuttle-fish ; in certain insects, as the
moths; but never, I believe, in birds. It is most largely developed in animals
which are nocturnal in their habits, or live like fishes in a medium which is dimly
illuminated. All must be familiar with the glare of light which it throws from
the eye of the cat or dog, when these animals exhibit dilated pupils in twilight.

This tapetum lucidum, has been a great stumbling block to physiologists. The
albino eye was set aside as abnormal; and the reflection of light in normal eyes
from the retina and choroid was overlooked, or regarded as accidental, but that from
the tapetum could not be. Most writers, however, dismiss it with an unsatis-
factory and very brief comment, unable evidently to reconcile its presence with
the maintenance of that internal darkness of the eye, which is supposed to be
essential to vision.

Thus, J. MUier, in the passage already quoted, alludes to dazzling from ex-
cess of light, and indistinct vision, as inevitable peculiarities of the tapetal eye.

WELL’s Colour-Top allowed us to test carefully, and with the result, that her sense of colour was acute,
precise, and normal. In short, her vision by diffuse light was optically as perfect as that of the
majority of mankind, and to appearance, a diminution in the sensitiveness of the retina was all that
was required to make vision equally perfect in direct light.

The iris in this case was pale blue, and the pupil was not pink by diffuse daylight. It became
so, however, in the neighbourhood of a gas flame, and her friends were familiar with the fact that by
gas-light, her eyes often “ flashed fire.”

We found it easy to observe this ocular luminousness at will, and the fact is important, as prov-
ing that the comparatively perfect vision which this Albino possessed, was exercised by eyes, within
which a large amount of cross-reflection of light was continually occurring.

EYE AS A CAMERA OBSCURA. 009

B. Prevost satirizes the belief, that a mirror within an animal’s eye can assist it
in seeing.* Dr W. Mackenzis agrees with him, and observes, that ‘“ Reasoning
4 priori, we should say that the tapetum would render the eyes weak, and impa-
tient of light.”’}

It is needless to discuss those opinions in detail. If in the eyes of those ani-
mals which have not tapeta, there is, as we may phrase it, simply permission for
internal reflection of light to occur; in those which have tapeta, there is plainly
direct provision for its occurrence; and it is astonishing to find writers of such
ability as those I have quoted, finding no function for the tapetum but that of dis-
turbing the vision of its possessor. We are often compelled to acknowledge our
ignorance of the function of an animal organ, but surely never to confess that it
was given to its owner solely to incommode or injure it! Only those whose
thoughts were preoccupied by the theory that the eye must be preserved a
camera obscura, could have brought themselves to credit and affirm that the horse,
the ox, the lion, the dog, the seal, or the shark, are animals that see imperfectly.
With the exception of birds, they are probably excelled by no animals in the
quality of their vision.

3. The last objection I have to notice raises the difficulty, that the known
laws of luminous reflection render it impossible that perfect vision can be per-
formed by an eye, across the chamber of which light is continually passing and
repassing. But if it be the case, as | have sought to show, that the most perfect
vision which comes under our notice is performed in spite of such reflection con-
tinually occurring, it is manifest that there must be some misconception regard-
ing the evil influence of cross lights within the chamber of the eye.

A little consideration will show, that as all the light which enters a normal
eye enters it by the pupil, and is refracted to a focus on the retina at a point
more or less directly opposite its place of entrance, if it is reflected from the re-
tina or choroid, it will in larger part simply retrace its course, and pass out
through the pupil as it entered by it. This escape of the reflected light through
the pupil, carries it clear of the internal walls of the eye-chamber, and, as we
have already seen, renders possible the construction of ophthalmoscopes.

Two circumstances may interfere with the exit through the pupil of the reflected
rays. 1st, The pupil suddenly exposed to bright light, may contract and diminish
its area before the rays which entered by it have had time to undergo reflection.
Jn that case the rays furthest from the centre will fall upon the back of the iris,
and undergo in part a second reflection from it. But the refiection thus occurring
will not be great, for special provision is made in all but Albino eyes for the stop-
page of such rays, by the great thickness of the uvea or pigment on the posterior

‘| surface of the iris, which has no highly reflective retinal covering like the choroid.

* Edin. Phil. Journal, 1827, p. 302. + Physiology of Vision, p. 220. «
VOL. XXI. PART II. AY

340 DR GEORGE WILSON ON THE

2dly. A good deal of light must undergo irregular reflection and dispersion
from the retina and choroid. But so much of this light as passes towards the
front of the eye will be arrested in greater part by the abundant pigment of the
ciliary processes, and anterior lateral portions of the choroid ; and what scatters
laterally will only produce a general excitation of the retina without developing a
second complete image of any visible object on the nervous membrane, which is
the chief optical evil to be apprehended from intra-ocular reflection. So long
as the direct seat of vision is not exposed to strong reflex illumination, and the
same entire pencil of rays does not twice depict the image of the same object on
different parts of the retina, and thus produce double vision of single things, the
general reflection and dispersion of light within the eye cannot do more than di-
minish the darkness of the eye-chamber as a whole. In the eye of the casual
albino, light is liable to be returned from the back of the greatly contracted iris to
the place of most perfect vision, and to disturb it, so that, as far as’ internal
reflection is concerned, he would be better without an iris at all. Moreover, his
iris is transparent, and is continually transmitting light from without as well as
reflecting it from within.

But even in the human albino, although unquestionably there must be painful
dazzling of the eye from the continual action of light on every point of the retina,
still, unless during sudden transitions from very faint to very bright illumination,
involving great and rapid change in the area of the pupil, the yellow spot or place
of perfect vision being opposite that aperture, will be less exposed than any por-
tion of the retina to the impact of light which has undergone intra-ocular reflec-
tion; and as the utmost contraction of the iris does not close the pupil, a pencil
of rays reflected from the yellow spot, can never return in toto to repeat upon
another portion of the retina the image which it has already produced upon that
spot.

It thus appears that the laws of luminous reflection do not necessitate imper-
fect vision, as applied to the fact, that the retina and choroid return much of the
light which reaches them, for :—

lst, In the normal and also in the albino vision of all animals, man included, the
amount of direct retinal and choroidal reflection is necessarily coincident with the
width or degree of dilatation of the pupil; the larger the pencil of light entering
the pupil, the larger the pencil leaving it, so that in every case the reflected rays
are thrown out of the eye and do not disturb vision: further :—

2nd, In those animals provided with tapeta lucida, such as the cat, the
dog, or the ox, which are only partially nocturnal in their habits, the tapetum is
so placed that in bright light it is not opposite to the contracted pupil, or is so only
to a small degree.* When, however, the choroidal mirror is called into action im —

* Joun Hunrer, in Catal. of Museum of Royal College of Surgeons, London. Vol. iii., p. 169.

EYE AS A CAMERA OBSCURA. 341

twilight, the pupil is correspondingly dilated, and all the light which the tapetum
reflects finds a free passage for its escape.

3d, In the eye of man, as well as in that of a large number of other animals,
the background of retina and choroid on which the image is depicted, is not the
darkest portion of the ocular screen, nor even so dark as those parts of the inner
walls of the eye on which objects are never figured. On the other hand, as JoHn
Hunter has shown, and illustrated by existing specimens, the front and the an-
terior sides of the eye-chamber are the darkest, so that the reflecting power is
greatest at the bottom of the eye.*

4th, In the human eye, where, more even than in those of the lower animals,
it has been contended that the conditions of a camera obscura must be realised,
the place of perfect vision, instead of being additionaily darkened, is occupied by
the well-known yellow spot, which has a marked reflective power, and is easily
discerned by ophthalmoscopes.

The results which are announced in the preceding argument may be summed
up as follows :—

1. The total absence of pigment from the choroid, the ciliary processes and the
iris is compatible (especially where this condition is hereditary) with perfect vision.

2. The replacement of the pigment of the choroid lining the bottom of the eye
by a concave mirror (¢apetum lucidum) powerfully reflecting light, characterizes
animals whose vision is very acute.

3. The non-tapetal or mirrorless eye of man, and of many animals, differs only
in degree from the tapetal or mirrored eye of others; for the retina and choroid
act as a tapetum, and reflect light in the same way.

4. The eyes of vertebrate animals are only to a limited extent camere obscure,
and internally are least dark in the portions most directly exposed to the action
of light, and where the seat of perfect vision is placed.}

5. The back of the iris, over which the retina does not pass, is the darkest in-
ternal portion of the eye in vertebrates; and next to it, in the majority of these,
are the ciliary processes of the choroid, and its anterior lateral portions.

* Hunter states that in animals where the pigment of the choroid is light in colour, “ the lightest
part is always at the bottom of the eye, becoming darker gradually forwards, and in such it is often
quite black ; viz., from the termination of the retina to the pupil ; or if not black, it is there much
darker than anywhere else. This is generally the case in the eyes of the human subject.” Catal.
Mus. R. C.S., London. Vol. i., p. 133.

{ Comparative anatomists must decide to what extent these observations demand qualification
in reference to particular tribes of animals. The-nocturnal lemurs, which have a uniformly coloured
dark choroid, no tapetum, and a very sensitive retina, probably exhibit intra-ocular reflection to a
small extent compared with other quadrupeds. A similar remark applies to birds, qualified by
the fact that the bottom of the eye-chamber is occupied in them by the marsupium or pecten, an organ
the use of which has not been ascertained, so that we cannot be certain how it modifies vision. But
as the researches of K6nx1ker and H. Miitter demonstrate that the general structure of the retina is
‘the same in all vertebrates, it appears certain that, however dark and absorptive of light the choroid
may be in some of them, the retina in-all will act as a mirror towards light incident upon it; and

342 DR GEORGE WILSON ON THE

From those premises the conclusion is deducible that in vertebrates much
light is reflected from the bottom of the eye-chamber during the exercise of vision
without disturbing it; but that little is reflected again, so as to return to the
bottom of the eye, in consequence partly of its absorption by the pigment of the
anterior portions of the choroid, partly of its escape through the pupil.

It may seem to some that this reasoning proves too much, for why is there in
man and many other animals a pigment at the bottom of the eye, if reflection
from the membrane there is so free to take place? To this I reply that the pig-
ment, which is never altogether inoperative, comes into special action when the
eye is exposed to very bright light, and saves the retina from the paralyzing in-
fluence of intensely luminous rays. Vision, however, cannot be continuously
exercised under such exposure, even where the light is not excessively brilliant,
in consequence of the instinctive closure of the eyelids, and the abundant secre-
tion of tears which then take place. The pigment at the bottom of the eye is
thus, I apprehend, a safeguard against sudden exposure to intense light; but
during continuous vision under an illumination which does not dazzle the eye, its
action is secondary as an absorber of light, and it always acts as a reflector.

Hitherto I have been arguing almost solely for the negative conclusion, that
the vertebrate, and especially the human eye, is not the kind of darkened cham-
ber which it has been supposed to be. It is impossible, however, to regard the
deep intra-ocular reflection which so certainly occurs in most animals, as an inci-
dental or useless phenomenon. That it has a direct and beneficial influence over
vision I cannot doubt, and I proceed briefly to indicate where the proof of this
is to be found.

Intra-ocular reflection, as a normal phenomenon, is at a maximum in the
tapetal or mirrored eye of the lower animals. It is desirable, accordingly, to —
study it first as occurring in them; nor can a better example of a mirrored eye
be found than that presented by the shark. In it the tapetwm lucidum occupies
the whole of the bottom, and one-half or more of the lateral surface of the cho-
roid, which is covered by pigment only in front. The iris, as in other fishes, is
incontractile, so that the diameter of the pupil never varies; and the tapetum,
which is colourless and very brilliant, is thus always in action as a reflector. The
shark, moreover, swims near the surface of the sea, where the amount of light is —
considerable, and the acuteness of its vision is proverbial. I have selected it, —
rather than a mammal, with eyelids and a contractile iris, because in the shark |
luminous reflection never ceases unless in absolute darkness; and when light is
shining occurs the more, the brighter the light is. Its eye thus is always in the —
the very curious observations of the latter author on the eyes of the cephalopoda (Quart. Journal of .
Micr. Science, July 1853, p. 269), show that the retina of these invertebrates will act in the same
way, a remark which, mutatis mutandis, may be applied to every creature, whatever its rank im the
animal scale, which has shining or so-called phosphorescent eyes. A most interesting field is open —

to naturalists in the examination, by means of the ophthalmoscope, of the eyes of living animals o:
all grades.

EYE AS A CAMERA OBSCURA. 343

condition in which that of a cat, or dog, or ox is, when subdued light causes
the iris to expand, and allows the reflecting tapetum to come into play, so that
the considerations which I have to urge apply to the mammal as much as to the
fish, provided they are taken with pupils equally dilated; but as the tapetum in
the shark is very large, very brilliant, and always in action, I shall restrict myself
for the present to it.

The light, which penetrates to the bottom of a shark’s eye, will, in part, be re-
flected from the retina (a phenomenon which for the present I disregard), in part
traverse it, and reach the tapetum, where a portion will be lost by absorption and
irregular reflection or dispersion, and (what alone concerns us here) in part un-
dergo direct reffection, return through the retina, and escape by the pupil. ‘This
returned light will impress the retina in traversing it, and illuminate external
objects on leaving the eye.

The first question, then, is, ‘‘ How will this light impress the retina?” Ac-
cording to J. Mitter and W. MackeEnziIg, as we have already seen, only inju-
riously, so far as freedom from the sensation of dazzling, or distinctness of
visual perception, are concerned ; according to Topp and Bowman “probably” by
‘increasing the visual power, particularly when the quantity of light admitted
into the eye is small.” * I have urged elsewhere that ‘“ what is equivalent to
two rays of light falling upon the retina will produce two impressions. We send
a capillary sunbeam through the retina in one direction, and instantly return it
through that membrane, a little diminished in intensity, in the opposite direction ;
if it determined a sensation in its first passage, what is there to prevent its doing
so in its second? If, for simplicity’s sake, we suppose exactly the same points
of the retina to be traversed by the incident and the reflected ray, then (unless
the luminous intensity of the incident ray was so great as by its passage to ex-
haust the sensibility of the retina), the refiected ray will repeat somewhat less
powerfully the impression made by the incident one. The difference will be as
great as there is between a sound and its echo, but not greater.

* On this view of matters, the tapetum, especially in twilight, will serve the
important purpose of making every perceived ray of light tell twice upon the
retina, so that the sensation it produces will either be increased in distinctness or
in duration, and probably in both.” t

I will not deny that we are not entitled at once to infer that because a molecular
change (modulation, vibration, polarization?) transmitted through a special struc-
ture in one direction produces a peculiar sensation, it will certainly produce the
same sensation on being transmitted through that structure in the opposide direc-
tion; but there are strong analogies in favour of such a view, and it is entitled to
' be regarded as a likely hypothesis.

* Physiology of Man, chap. xvii., p. 23. + Researches on Colour-Blindness, p. 99.
VOL. XXI. PART. II. 4Z

344 DR GEORGE WILSON ON THE

The first probable use of the tapetum, then, is to double the impression which
light produces upon the retina, whilst that light is within the eye.

The greater part of this light, however, after traversing the retina with little
diminution by absorption, passes outwards through the pupil, and, along with the
light reflected from the retina, is thrown upon external objects, and illuminates
them. A singular reluctance has been shown by physiologists, especially in recent
times, to acknowledge this. The supposed necessity of maintaining the chamber
of the eye dark, the apparent impossibility of the eye reflecting and receiving
light simultaneously, and the faintness of the light emitted from tapetal eyes,
have led most writers to contemn the doctrine that the tapetum is a serviceable
reflector of light. But the objections to this doctrine are in reality of no value,
and were not entertained by the older writers, such as HunTER and Monro, who
not only regarded the tapetum as casting light on external objects, but, in the ~
case of graminivorous animals, as affording them, by the green colour of the light
which is reflected, an assistance in discovering their food ; an opinion which Cuvier
in part countenances. .

As I have discussed this question at length elsewhere,* I shall merely observe
here that as the light emitted from a cat’s or a shark’s eye, ex. gr., is veritable —
light, there is no room for affirming that its illuminating powers are not, ceteris
paribus, equal to light of the same quality from any other source. If we can see
a cat in the apparent darkness, which otherwise would render it invisible, by the
light which issues from its eyes, it cannot be questioned that it will see us by so
much of that light as our persons reflect back into thoseeyes. The tapetwm luci-
dum is, for every creature which possesses it, a lantern, by which it can guide
itself in the dimmest twilight, and make each ray of light do double or triple ser-
vice, in assisting it to steer its course, and to find its food or prey.t

But if the tapetum assists carnivorous animals in finding their living prey, it
must also give the latter warning of the approach of the destroyer. I am not
aware that this use of the tapetum has hitherto attracted attention. t But a lion
or a shark does not more certainly bring into view, by means of tapetal light,

* Researches on Colour-Blindness, pp. 88-100.

+ Joun Hunter fully recognises this function of the tapetum, but (unless I misunderstand his
meaning) regards it as useful to its possessor solely by reflecting rays of light ‘ on the very object
from which they came”—(On the Colour of the Pigmentum of the Eye, Hunter’s Works, vol. iv.,
p. 285),—so that, on their return from this object, they “ strike exactly, or nearly, on the same —
points in the retina through which they first passed” (Op. et loc. Cit.), and increase the visibility of
the object in question.

This undoubtedly will be the result where the eye of the animal remains for some interval of
time perfectly at rest ; but the movements of a shark, cw. gr., are sufficiently rapid to enable its eye to —
receive light from one object and reflect it upon another, from which it receives it again, so that the
rays sent from the first body enable it to see the second; and this, I apprehend, is as much the fune-
tion of the tapetum as deepening the visual impression of the same object.

+ I suggested it last autumn in Researches on Colour-Blindness, Edin. Monthly Med. Journal,
September 1854, p. 234.

EYE AS A CAMERA OBSCURA. 345

the creature it would devour, than it betrays its own presence to that creature,
and the balance is thus mercifully maintained between the preyer and the prey.
That singular “ hypnotising” or ‘‘ mesmerising” power which, in the case of the
serpent, is called “fascination,” is probably largely possessed by the glaring
tapetal eye, which acts with all the advantage of surrounding darkness to in-
crease its impressiveness, and prevent other objects from distracting the attention
of the subject of fascination. On the other hand, however, the tapetal light is
peculiarly startling to an observer, for it is always coloured and unlike that of
day, resembling in character (in the case at least of the cat and the dog) those
fluorescent rays of the spectrum, which Mr Stoxes describes as “ ghostly,” and
of which it probably largely consists. At all events, its unfamiliar appearance
specially qualifies it to alarm creatures who suddenly perceive it, and are led by
instinct to flee from all strange lights.+

In the lower animals, then, the tapetum is probably serviceable—

1°. By doubling within the eye the impression of each ray upon the retina.

2°. By reflecting light from the eye upon external objects, so as to render food
or prey more visible.

3°. By warning, through the agency of that light, creatures on which carni-
vorous animals prey, of the neighbourhood of their enemies.

In the discharge of those functions the retina more or less conspires, differing
from the tapetum chiefly in reflecting a less coloured light than the latter does.
Further, in such of the lower animals as have not tapeta, there must occur in most,
alike from the choroid and the retina, and in all at least from the retina, reflection
of light. In those whose eyes exhibit choroidal reflection, the same good ends will
be served by it, though in a much less degree, as are secured by tapetal reflection,
and of these probably the most important is the first, which cannot be attained
with light reflected from the retina.

How far human vision is sensibly influenced by the choroido-retinal reflection
which is continually occurring within the living eye, it is difficult to decide; but
it must be influenced to some extent by it. It seems probable that the acute
vision in faint light which characterizes those who are imprisoned in dark cham-
bers, and which the astronomer sometimes purposely induces by long shading of
his eyes before making observations, is in part due to the return of light from the
choroid through the retina; in part to the passage through the highly-dilated
pupil of light reflected both from the choroid and retina, which is thrown upon

+ Colonel Mappen, H.E.I.C.S., who was present when this paper was read, informed me afterwards,
in reference to the subject discussed in the text, that in India, where he had served for many years, he
had had occasion to verify the truth of the statement made above, so far as one animal is concerned.
In a district at the foot of the Himalayas much infested by tigers, the natives, according to their
own statement, were frequently afforded timely warning of the approach of these animals in the dusk,
by the glare of their eyeballs, which the men compared to ‘ yellow pumpkins.”

346 DR GEORGE WILSON ON THE

external objects. It may startle us at first to be told that we see in part by light
issuing from our eyes, but it must be so; and those traditions of learned men who
could read by the light of their own eyes in what was darkness to others, are only
exaggerations of a power more or less exercised by every human organ of vision.*

To one result of this choroido-retinal reflection in the human eye I would, in
conclusion, refer. The light which is thus reflected, is always coloured, being, as
we have already seen, red, yellowish-red, or brownish-red, and differing neces-
sarily in its tint, according to the abundance of pigment in different eyes. Each
of us thus adds to every object on which he looks so much colour, but no two
pairs of eyes the same amount, and hence one great reason why no two persons,
almost, will be found to agree as to the matching of one colour with another
where the coloured substances compared consist of different materials; and why
very marked differences present themselves in the judgments of persons equally
practised in observing and copying colours.

Two artists, for example, paint from nature the same fiower. The pigments
which they employ for this purpose, will, of course, be as much affected by the
colour communicated from the eye, as the flower is, so that, could the latter be
imitated in its own materials, the copies might be identical. But as these must
be made with substances whose lustre, transparency, and particular tint, differ
from those of the body copied, the added colour from the eye tells unequally on
the original and the copy, as compared together, and as seen by different eyes.
Each, accordingly, objects to the other’s colouring, but neither can induce his
neighbour to adopt his tints, and both appeal confidently to third parties (who
perhaps differ from both), assured that the adjudication will be in favour of the
appellant. Here each may have been equally skilful and equally faithful: and —
neither has any means of testing to what extent he sees everything as if through
coloured spectacles, which give all objects a tint for him inseparable from their
natural colour. A ‘chromatic equation,” thus originated, belongs, I believe, to
every eye.

* Esser on the Luminousness observed in the Eyes of Human Beings, Edin. Phil. Journal,
1827, p. 164.

—*

qo
1
bo |

EYE AS A CAMERA OBSCURA.

Postscript.

From my friend, Professor Goopsir, who recently (June 27th) delivered a
lecture of great interest and originality, on the Retina, to the Anatomical Students
of the University of Edinburgh, I learn that, as he stated to his hearers, his micro-
scopical observations on the structure and development of the eye had led him
to the conclusion, that only the rays of light which are returned from behind
through the retina produce a luminous sensation, and that the objective percep-
tion of light commences physically towards the choroidal, not the hyaloid extremity
of the optically sensific constituents of the retina.

According to BRUCKE (as mentioned in the text, Note, p. 334), the bacillar layer
acts as a mirror, reflecting light forwards, and luminous sensation begins in a
layer of grey nervous substance, situated nearer the front of the retina,—an opinion
combated by Kouuiker.

According to Mr Goopsir, the objective perception of light begins somewhere
near the junction of the rod or cone with the Miillerian fibre (see Note, p. 332).
On this view, the entire arrangement of rod or cone, with its Miillerian filament,
is not a nerve-structure, as KoLuiker holds, but a peculiar organ referable to
the same category as the tactile corpuscles and Pacinian bodies, and so con-
structed as to oppose the extremity of the nerve, which is contained in it, to the
ray of light passing backwards from the choroid along the axis of the rod or cone,
so that the ray shall impinge upon its extremity in the line of its axis, this being,
according to Mr Goopsir’s hypothesis, the only direction in which a ]uminous ray
can optically affect a nervous filament.

I have argued, in the preceding paper, for such returned light being accessory
to vision, but according to this view it is the only light by which it is exercised.
If this doctrine (however modified in details) be established, the reflection of light
from the choroid will prove to be essential to the functions of seeing, and the necessity
for the living eye being a Camera Lucida will be based upon deeper grounds of proof
than I have attempted to offer.

August 10, 1856.

VOL, XXI PART III. 5A

( 349 )

XXII.—On Errors caused by Imperfect Inversion of the Magnet, in Observations of
Magnetic Declination. By Witt1am Swan.

(Read 30th April 1855.)

1. A compass needle, although freely suspended, will not always point with
accuracy in the direction of the magnetic meridian, for its magnetic axis may not
be strictly parallel to its axis of figure; and hence, when a rigidly exact value of
the magnetic declination is required, it is necessary to take the mean of at least
two observations of the needle, first, in its usual position, and next, inverted. Some
time ago it occurred to me that the declination obtained in the manner now
described, will only be approximately correct, unless the inversion is accom-
plished with perfect accuracy; and I wished to ascertain the greatest residual
error which, in given circumstances, is likely to affect the mean of two obser-
vations of a magnet, first in an erect, and then in an inverted position. I failed,
however, to find any allusion to such errors in those works on magnetism to which
I had access; and I was therefore obliged to investigate the subject for myself.

2. There are three forms in which a suspended magnet has been used to ascer-
_ tain the magnetic declination. Fist, The ordinary compass needle, traversing a
divided arc, or having a divided card attached to it; secondly, The magnet, having
a small mirror attached to it, in which the divisions of a fixed scale are seen by
reflexion, and observed by means of a fixed telescope; and, thirdly, The magnet
converted into a collimator, by attaching to it a lens with a divided glass-scale,
or cross fibres placed in its principal focus. I will consider the declinometer
magnet only in the last of these cases, where the collimator is observed through
the telescope of a theodolite; but the formule for computing the errors due to
imperfect inversion will apply to any kind of magnet. I will also at first assume,
that the magnet turns on its point of suspension without friction, or that it is
suspended by a fibre without torsion, and that no change occurs in declination
during the observations. These assumptions, it is evident, will in no way affect
the accuracy of the reasoning; for, as torsion of the suspension-fibre, changes of
declination, and imperfect inversion of the magnet, are all totally independent
sources of error, which must be either by some means avoided, or have their
effects separately computed and applied to the observations, so also the theories
of these errors may be separately discussed.

Definition of Accurate Inversion of a Magnet.
3. Let ZO, Fig. 1, (Plate VII.) be a vertical line passing through the point of
suspension of the magnet; C being either the point on which the agate cap sup-
VOL. XXI. PART II. 5B

350 : MR WILLIAM SWAN ON OBSERVATIONS

porting it rests, or ZO, the torsion-fibre by which it is suspended. We may
then suppose the magnetic axis to be transferred parallel to itself, until it passes
through O, without altering the direction which the freely suspended magnet
will assume; and, in like manner, the observed direction of the magnet will
remain unchanged, although we suppose the optical axis of the collimator at-
tached to it to be transferred parallel to itself, until it passes through O. Let
AA’ represent the direction of the magnetic, and BB’ that of the optical axis, and
let a spherical surface described about O meet the lines OA, OB, OZ, in the points
A, B, Z; then the circle Z N z will be the plane of the magnetic meridian, and the
spherical angle AZB, or the arc NC of the horizontal circle NESW, will measure
the horizontal angle between the optical axis of the collimator and that plane.
It is obvious, also, that we may include the cases of the ordinary compass-needle
or of the magnet with an attached mirror, if in the one case, we conceive OB to be
the axis of figure of the needle ; or ifin the other, we suppose that a pencil of rays
proceeding from the fixed scale along a given line, such as NO, and falling on the
mirror at O, is reflected to B.

If now, when the verniers of the theodolite employed to observe the magnet
indicate zero, the optical axis of the theodolite-telescope is in a plane parallel to
the plane ZOD, the arc DN will be the true, and DC the apparent reading for
the magnetic meridian.

Hence, if the arcs DN, DC, and NC, be represented by o 0, and ?. we shall
have the apparent reading for the magnetic meridian,

0, =oO+ p.
Next, let z, instead of Z, be taken as the point of suspension, the angles AOB,
AOZ, BOZ, all remaining unchanged, then the magnet will be in precisely the
position which it would occupy if the whole figure revolved about the line NS,
until z coincided with Z.
If then a O, 0 represent the new positions of AO, BO, we shall have
46 = a2bh>AZB = >;
and if eD=6,,
é; = 6- ?,
where 0, is the apparent reading for the magnetic meridian in the new position
of the magnet.
Finally, adding, ¢ is eliminated, and we have
= 40, te 05)

which shows, that if the magnet be inverted, in the manner described, the mean
of the readings in the erect and inverted positions will give a rigidly accurate
result.

OF MAGNETIC DECLINATION. 351

It will be observed, that unless the apparatus has been disturbed in the process -
of inversion, the angle AOB will remain unaltered. It is otherwise with AOZ,
and BOZ, which do not necessarily remain unchanged, after the point of suspen-
sion has been transferred to z, or the magnet has been inverted. We may there-
fore define accurate inversion of a magnet to mean, that, a vertical straight line
being supposed to be rigidly connected with it, the magnet is turned round its
axis, until the line, moving along with it, becomes again vertical ; the inclina-
tions of the magnetic and optical axes to the line, thus remaining unchanged after
inversion.

4. When the magnet has been inverted in the manner now defined, the mean of
the readings, in its erect and inverted positions, gives a correct value of the mag-
netic declination. It does not, however, follow, that no other position after inver-
sion would secure the same result, for it is obvious that a curve might be described
on the surface of the sphere, such that, for all points in it, the angle a Zb should
- be equal to AZB; and if the magnet were suspended from any of these points, we
should still have the desired condition fulfilled. We might also have the magnet
inverted, so that the arc AB revolved until it made an angle with ZA on the
opposite side of the line, and equal to ZAB. No importance, however, attaches
to the existence of these different modes of inversion; for one method, answer-
ing the desired conditions, is sufficient, and the one which has been defined as
accurate inversion seems to be that most easily effected.

5. It remains, however, to be shown that the magnet will remain in equili-
brium in the new position of accurate inversion. For this purpose let AA’,
Fig. 2, be the magnetic axis, ZO a vertical line passing through the point of
suspension, and G the centre of gravity of the magnet, which, in the position of
equilibrium, will be in the same plane with AA’ and ZO. The magnet is then
kept in equilibrium by the forces at A, A’, the weight of the magnet acting at G,
and the tension of the suspension fibre acting in the line OZ.

Let m = the force of free magnetism in either pole,
w = the weight of the magnet ;
and put
AO=4a, AO = 6, GO =.c;,
AZOR = AZ Omar AOZ =A), GOZ = x.
Then we have
m(a@ + 6) sin(A + 1) — we sing = 0.

After inversion : remains unchanged, but \ and 7 may be supposed to change to

_X and 7; while the new point of suspension may either be the former point 0,
or any other point in the line ZO z; and we shall in like manner obtain,

m(a + 6) sin(AN’ + 1) — wesiny = 0;

352 MR WILLIAM SWAN ON OBSERVATIONS

sin(A +1) _ sing ,

sin (A’ +1) Sing!

Now if the inversion has been accurate, according to definition, we should have
Rese ending = 180" = 5.

Hence

Therefore

sin (A + 1)

sin (A’ — 1)
a condition which, as : may have all values from 0° to 90°, can only be satisfied
by A = 90° or A = 270°; that is, when the magnet is suspended with its magnetic
axis horizontal. Such is the position which the magnetic axis is made to assume
in practice, with more or less accuracy; and it therefore follows, that the magnet
may remain in equilibrium after accurate inversion.

== ile

Inaccurate Inversion of a Magnet.
6. We have next to inquire what will be the errors occasioned by imaccurate
inversion.
In fig. 1, let AB=a, BAZ=6, BZ=4,, AZB=9,;
and after inversion, let
bia Zi 0.3 Bis le, AL b= Os,
while ab = AB= a,
Also, as before, let
DN = 0, DC = 0,, De=60,
Then the observed angles for the magnetic meridian are
6. = 0+ ¢,, 0,=0- ®,
From which
= 4 (0, a 05) —3(%, = Ps)
= 4 (0, nig 0;) — €;
where the error committed by taking the mean of 6, and 0, for 9, is

€ = 3 (, — 95):
Also in the triangles ABZ, ab Z, we have
sing, = eee, sin p, = Sans,

from which equations, supposing the other angles to be known, ¢,, and ¢,, may
be calculated, and ¢, the correction to be applied to 6, may be obtained.

Method of ascertaining the relative positions of the Magnetic and Optical Axes in a
Collimating Magnet.

7. It thus appears that we can calculate the error in the determination of
magnetic declination due to imperfect inversion, provided we know the angles —
a, 8, and 4, both in the erect and inverted positions of the magnet.

OF MAGNETIC DECLINATION. 353

The angle y can be ascertained with the utmost accuracy by direct observa-
tion, for it is the supplement of the zenith distance of the collimator-cross, as
seen through the theodolite-telescope: but the ordinary methods of observation
do not afford sufficient data for ascertaining the angles a and @. I have found,
however, that these angles may be computed, provided we observe the magnet
not only erect and znverted, that is when turned round its axis 0° and 180°, but
also when turned round 90° and 270°.

8. In order to put this mode of observation in practice, I had a small colli-
mating magnet constructed by Mr Apiz, shown in fig. 3, consisting of a hollow
steel cylinder 2-1 inches long, 0°5 inches in diameter, and about 0-04 inches thick,
furnished at the end N with an achromatic lens of about 2 inches focal distance,
and 0°3 inches aperture, and at C with a diaphragm carrying a cross of fine
spider-lines. The diaphragm is supported by four screws, s, having their beads
so deeply sunk below the surface of the cylinder as to be out of risk of dis-
turbance; and the cell of the lens is made to screw into the cylinder, in order
to adjust the cross-wires to its principal focus. The cylinder having been placed
in temporary Ys, the lens was screwed in, until the wires were distinctly visible
through the theodolite-telescope, which had previously been brought to sidereal
focus; and then, by means of the screws s, the diaphragm was adjusted until
its cross-wires continued nearly to intersect those of the theodolite-telescope,
while the cylinder was turned round in the Ys. In this manner, the line of col-
limation was rendered nearly parallel to the axis of the cylinder, and thus also
approximately parallel to the magnetic axis.

9. On the cylinder there is a tightly fitting brass ring A, having on its sur-
face four lines, two of which, marked 1, 4, are shown in the figure; and the cy-
linder itself turns without much friction in the ring B, to which the torsion-
fibre of silk, F, by which it is suspended, is attached. The lines on the ring A
are situated 90° from each other, and are marked for reference 1, 2, 3,4; and
the ring B having also a line marked 0 upon it, with which the lines on A may
be made successively to coincide, the cylinder may be suspended, either in its
usual position, or turned through 90°, 180°, or 270°. The ring A was turned on
the cylinder, until, when the lines 1 and 0 coincided, the wires of the collimator
were sensibly horizontal and vertical,—a condition which was known to be ful-
filled when, on looking through the theodolite-telescope, it was possible, by means
of the tangent-screws, to make the vertical and horizontal wires of the theodolite
cover those of the collimator.

* In figures 4, 5, and 6, AB, CD are the wires of the theodolite-telescope, and ¢/,
_ gh those of the magnet-collimator, represented, for the sake of simplicity, as they
would appear when viewed through an erecting eye-piece. In figure 4, the mag-
net is in its usual or erect position, which is known to be the case when a small
index 7, projecting from the edge of the diaphragm, is seen uppermost. In fig. 5,
VOL. XXI. PART II. 5 C

354 MR WILLIAM SWAN ON OBSERVATIONS

the magnet is also represented as in its erect position, but inaccurately so; and
in fig. 6, it is represented as inaccurately inverted ; while in both figures the inter-
sections of the theodolite and magnet wires have been brought into optical coinci-
dence, in order to read off the magnetic declination. Since the optical axis of the
collimator coincides approximately with that of the cylinder we may assume that
the magnetic axis is turned round the line OB, fig. 1; and if, in figs. 4, 5, 6, Zoe
be an angle equal to the inclination of the planes AOB, BOZ, fig. 1, we may, since
the angle AZB is small, assume that /o¢ is sensibly equal to the inclination of
the planes AOB, AOZ, or to 8.* The angles Aoe, Boe will then, with sufficient
accuracy, represent the errors in the values of @ in the different positions of the
magnet, and those angles may evidently be either estimated, or measured by means
of a position-micrometer. The micrometer I have employed for this purpose con-
sists of a piece of plate-glass, having on it a small circle about 0°25 inches in dia-
meter, divided to every five degrees, by means of a fine diamond point. The glass
is cemented with Canada-balsam to the flat surface of the field-lens of a RAMSDEN’s
eye-piece, and its thickness is such, that when the diaphragm-wires are brought to
focus, the divided circle is so close to them as to be also very nearly in focus, so
that its divisions are sufficiently well defined. The angle AEO can then be easily
estimated to the nearest degree.

In the usual position of the magnet, fig. 5, let

Ons, 5 AVE = %5 Col = 1G.
Then 6b, =B+%,-

Similarly, when the magnet is inverted, fig. 6, reckoning the angle AO/ in the

direction ACBD, let

INOW Mesa: 8 BOe =,
Then B, = 180° + B + ¥5:
where, as the angles @, and @, are measured always in the direction ACBD, the —
angles y, and , are to be reckoned positive or negative, according as they are
measured in the same or in the opposite direction.

If, now, the magnet be inverted again and again, causing the lines 1 and 3 —
alternately to coincide with the line 0, and if, after each inversion, the cross-wires
of the theodolite be made to intersect those of the collimator, we shall obtain the ~
following series of readings :—

1st, From the verniers of the horizontal limb of the theodolite,

6= 04+ 9,3; and 0, =0 —.o2
2dly, From those of the vertical limb, the zenith distances of the collimator-cross,
NGO yond eye BON aM
* Supposing BAZ or B=45°, AZ=90°, and AZB=1°, the error in the value of @ introduced —

by this supposition is only about 31”, which would not appreciably affect the subsequent calculations; —
and as AZB need not exceed 5 or 10’, the error in 6 will generally be much smaller. i

OF MAGNETIC DECLINATION. 355

3dly, At each observation we may also register the values of the angles
ry, and +,, the inclinations of the collimator-wires to those of the theodolite, as
found by estimation or otherwise.

10. The readings 6, and 0, will be affected by changes in declination occurring
during the observations; which, however, may be eliminated with sufficient ac-
curacy, by combining each reading with the mean of the preceding and subse-
quent ones. At each observation, also, the values of @, or 6, will be incorrect,
owing to imperfect inversion, the errors being y, and y,; but, as the latter angles
may be expected to have sometimes positive and sometimes negative signs, the
errors in the individual observations may be eliminated more or less completely,
by taking the mean of a sufficient number of readings.

_ We shall thus obtain the angles

?, + $; = 6, —6,, ~, and ¥,; and with more or less accuracy,
GC, = Bb, and Bs = 180° + GB.

Similarly, if the magnet be repeatedly inverted, with the lines 2 and 4 alter-

nately coinciding with the line 0, we shall obtain, in like manner,
Pp, + @,=0,-6,, p and », ,
GB, = 90° + B nearly, and 6, = 270° + @ nearly.

If now, as before, we suppose the magnetic and optical axes, and a vertical
line through the point of suspension, to meet a spherical surface in the points
A, B, Z, we shall have, in fig. 7, A, B, Z, A,B, Z, A, B, Z, A,B, Z, for the posi-
tions of those points in the four positions of the magnet, and we shall obtain

sng, _ sina ~ sng, _ sind
sin 6, sin y, ” sin 6, sin),
from which, substituting the values of @,, @,, &c, in terms of 3, we have
Sm: sina sin ~, sin @
DOS 7/0 Fe hae Le ee 5 = 5 ?
sin 3 sin), sin 3 sin p,
sng, - sina sng, sina
cos @ sin y, cos sin,
Whence
BG ae gd, + sin p sin aa sin \,
sin), + sin ~, sin @
angus ~, + sin Ps sin bs sin \,
sin, + sin y, sin &
Therefore

tan 6 = S24 (bs + Ps) 008 3 (p15) sin 4 (Hy +.) 008 4 (“Hy—H,) Bin Y, sin,
sin 3 (p, + P,) cos 4 (P,—,) sin $ (Wb, +5) cos $ (Wb, —Y,) sin y, sin >,

and sina = sin $ ($, + P3) cos 3 (P, — Pf) sin, siny,
sin § (, + 45) cos (, — ¥,) sin @

356 MR WILLIAM SWAN ON OBSERVATIONS

11. In these formulee the angles, in terms of which a and @ are found, are all |
given by observation except ¢,—?, and ¢,—¢,. As, however, these angles are
small, their cosines will differ little from unity: and since also ¥,, ),, &c., are all
nearly equal to 90°, we may evidently, for an approximation, assume all the fac-
tors on the right hand, except sin} (¢,+,) and sin 3(p,+,) as equal to unity.

Then since

$, + $, =0, — 95 and p. + , = 9, — 6,

we shall obtain
sin 4 (0, = om) :

tan b> = —
6 sin} (0, — 0,)
ig) Sones in i 2
sin = 2A = Sas G, nM) or sina = SUB io. ~ Me) 6; 84)
sin 3 cos 3
Formule for calculating the Errors occasioned by Imperfect Inversion of a Declinometer
Magnet.

12. Having thus found approximate values of a and 8, it will be seen, on
referring to the equations of Art. 6, that we are in possession of all the data ne-
cessary for calculating, from those equations, ¢, and d, and hence e, the correc-
tion to be applied to the observations of the imperfectly inverted magnet. If,
however, formule for calculating « directly be preferred, the following may be
used :—

1. In the erect and inverted positions of the magnet, we have the equations

SD, 80, sing, _ sin,

sin a@ sin), ’ sna ~~ sind,’

where y, }, are found by observation, also 6,=@+ +7, and @,=@6+4,;
y, and ‘y, being found by observation, and a and @ calculated by the formule of
Aitood ee

Then remembering that

?,+o,= 6 -9,,

sin a
8 sin p, sin p, cos 3 (0, — 05)

and putting
cos 0 =
it may be shown that
sin € = cos(0 + 4, + B,) — cos(O — J, — B,)+ cos(O — 4, + 6,) — cos(6 + +, — 3)
— cos (0 + , + B,) + cos(O — Y, — B,) + cos(O + $, — B,) — cos(O — y, + B,)
13. More convenient formule, however, may be obtained by calculating the
errors in the resulting value of the magnetic declination on the supposition that —
variations take place in the values of @ and y separately. :
lst, If errors occur in the values of 6 alone, we may suppose y to have its
correct value, which, as shown in Art. 5, is 90°.
The equations of last article then become

sin d, = sinasinG,, sing, =sina sin,

OF MAGNETIC DECLINATION. 357

from which, if «, be the value of the error in the observed declination expressed in
seconds of arc, we have

4 sin a@ cos} (G, + (,) sin 4 (8, - 6;) .

j sin 1” cos (0, — 0,)
2dly, If errors occur in the values of » alone.
Let y= 90°-%, +; = 90° —
Then supposing @ to have its correct value
; sin @ sin d sin @ si
sin p, = mar ye ‘ sin, = Aas 7 6

and putting ¢«, for the error in seconds in the value of the observed declination,

_ sina sin@ sin} (@, + @,) sin} (%, — %,) .
sin 1” cos %, cos Z, cos $ (0, — 05)

€

Finally, if « be the error in declination arising from simultaneous errors in the
values of @ and y, since the whole error produced by imperfect inversion will
generally be small, we shall have, with sufficient accuracy,

€=> 62+ €,

14. To give some idea of the extent of the errors which may be expected to arise
from inaccurate inversion, I will assume the case of a magnet which, when accu-
rately inverted, gives a difference of 20’ in the theodolite readings; and also, that
in the erect position, ,=90° and 8=45°. The following table shows the errors
in declination due to imperfect inversion of such a magnet, corresponding to the
tabulated errors y and Z in the values of 8 and ¥, respectively, after inversion,
these errors being supposed to occur separately.

Y 2° 4° | 6° 8° LO™

eG arm 2902' 8) oon z a gee!) 2477-5

It thus appears that errors in @ affect the accuracy of observations of declina-
tion much more than those in y, a result which might have been anticipated ;
and also, that an error in @ of only 2° would, in the assumed case, cause an
error in the observed declination exceeding 10',—a quantity quite appreciable
in such observations.

VOL. XXI. PART II. 5D

358 MR WILLIAM SWAN ON OBSERVATIONS OF MAGNETIC DECLINATION.

15. It was originally my intention to give an example of the application of
the formule which have now been investigated, to the correction of an obser-
vation of absolute declination made by means of the magnet described in Arts.
8, and 9; but hitherto I have been unable, from want of leisure, to undertake
such a series of observations as would be necessary to secure a trustworthy re-
sult. I will therefore merely state, in conclusion, what I conceive are the prin-
cipal uses to which the formule may be applied.

1st, The greatest error likely to occur in inverting a declinometer magnet
having been ascertained by a sufficient number of observations, the greatest cor-
responding error in the observed declination may be computed. This may be
found to be so minute as to render it unnecessary to make allowance for such
errors in future.

2dly, If the errors in the observed declination are found to be appreciable, the
most convenient course seems to be, first, to find a and @ by the formule of
Art. 11; and then, by the formule of Art. 13, to calculate a table of errors. The
corrections of the individual observations could then be at once obtained by in-
specting the table.

3dly, The formule may be useful in indicating to the observer the proper in-
strumental adjustments for diminishing the errors caused by inaccurate inversion.
It is evident, from the formulze of Art. 13, that the errors ¢, and ¢, are least when
a is least, and @=90°. In the form of the magnet described in Arts. 8 and 9, it
is obvious, that provided the position of the line of collimation referred to the
magnetic axis be known, a may be diminished by means of the adjusting screws of
the diaphragm, and @ may be brought approximately to 90° by turning the ring
A, fig. 3, through the proper angle.

( 359 )

XXIIL.—On a Problem in Combinations. By The Rev. Pattie Kevuanp, M.A.,
Professor of Mathematics in the University of Edinburgh.

(Read 3d December 1855.)

Several years ago, when discussing the question of the distribution of the stars,

a problem occurred to Professor Forpes, which, simple as it is, appears to have
escaped notice prior to that time. Having been consulted as to its solution, I
communicated my results to Professor ForBes, who has inserted one of them in
his paper printed in the Philosophical Magazine for 1850, vol. xxxvii., p. 425.
But for the very ingenious application which Professor Forses has there made of
it, the problem might probably not be worth recurring to. As it is, I have thought
it would not be altogether uninteresting to give the complete solution.
- The Problem is as follows:—There are m dice, each of which has p faces, p
being not less than 7; it is required to find the number of arrangements which
can be formed with them, 1°, So that no two show the same face; 2°, That no three
show the same face; 3°, That no four do so, and so on.

1. The number of arrangements in which no two show the same face is easily
seen to be the same as the number of permutations of the p faces, taken 7 to-
gether; and is therefore p (p—1) (p—2)....(p-—n+1).

2. Remove the dice A and B, and cover the face 1 of the remainder. The
number of arrangements which these can now form, omitting the covered face,
and no two showing the same face, will be—

(p-) (p—2). . . . (p—1-n=2+1)
Do (p- 2). -(p—n+2).

Place with each of these the dice A and B, showing face 1, and you fee the
arrangements in which the dice A and B, and these alone, show face 1. The same
applies to each of the other faces. Consequently there are p (p—1)... .(p—”+2)

rrangements in which the dice A and B, and these alone, show the same face.
The same is true of every other pair of dice. Hence the number of arrangements
in which two, and two only, show the same face, is—

os uy

p(p—-l)... .(p—n+2).

3. Remove the dice A, s C, D, and cover the faces 1 and 2 of the others.
The number of arrangements which can now be formed in which no two show the
. same face is—

—2) (p—8)....(p—2—n—441)

=(p—2) (p—3)....(p—n+8).
VOL. XXI. PART III. SE

360 PROFESSOR KELLAND ON A

By placing A and B showing face 1, and C and D showing face 2, with each of
these, you have the arrangements in which two particular duplications of the dice
A, B, C, D, and those only, occur. Now the number of arrangements of faces 1
and 2, on dice A, B, C, D, is the number of permutations, all together, of four

things, two of one kind and two of another, or, a
4.3 = sone 1
Hence (p—2) (p—3).-. -(p—n+3)

is the number of a cee in which two duplications occur of faces 1 and 2,
and on dice A, B, C, D. The same is true of any other pair of faces ; consequently
the number of arrangements in which two duplications are found on the dice A,
B, C, D, but on no others, nor any repetition of the faces shown on these four
dice, is—

it) t ae es -

Die ee) PAE MS (p=2) (op =ae eyaaee 3):

In like manner, any other four dice form the same number of arrangements ; and
hence the total number of arrangements in which two duplications and no more
occur, 1sS—

4.3.2.1 n(n—1) m—2) n—38 if
a BP (P—D)-- - «(pn 48).

4. Similarly, the number of arrangements in which three duplications, and
three only, occur without any other repetition, is,—

6.5.4.38.2.1 n(m—1)....(m—S) 1
2° ea eee ‘ Tra7g P (p-1)-- - -(p—n+4),

and the law of formation is evident.
5. We may now write the number of arrangements in which no triplication
occurs, in the following form :—

p(p-1)... .(p—n+1) +” 22) p (p-1)... . (p—n +2)
Y pe é CEN ne Oe) ean (pAayialy eae
Ee Oe yeu oa
=p (p—1).- (pant) { 1422). 54
n(n—A) tae s3)y ned) AGS 1

(p—n+l)(p—n+2) 1.2° 2* (pont l) @—n42) @—n+F 8) 1.2.8" prke }

6. This series may be exhibited as the solution of a differential equation, but —
it is doubtful whether, with our present knowledge, we can simplify its form. We
obtain the differential equation thus :—

n (n—1) 2 (n—1)... (n—3) &?

So &e.

me walt p—wel ?* Gant 1) (peewee) 1

PROBLEM IN COMBINATIONS. 361

i ae a ee ae rary ae
igs ae — ig the
(7-32) =n (n—1) a" + nO a eat:
BOD lt Fs
=n (n—1) Zs, men), he aE
when C= =
Hence fron—s S nual = =. CG u) ;
or Sa ais 2 ae u —2p+2n 7a

=4,° = eee Hey (n—1) ou:

whence (e—4 a?) +{p- nt+1+ (4n— 6a Te —n(n— Ly w=0.

7. To find the number of arrangements in which no quadruplications occur,
let us write the result of Art. 5 under the form Cos being the total number of
arrangements of n dice, each having p faces, in which no triplications occur.
Remove the dice A, B, C, and cover the face 1 of the others. Then Cw rhs is the
number of arrangements of those dice in which no triplications occur ; and,
consequently, the number in which A, B, C, and those only, show face 1. Hence
Dp om is the number of arrangements in which a triplication is found on the
first three dice, and on those alone. Consequently the number of arrangements
in which one triplet only occurs is—

ace

5 Remove the dice A, B, C, D, E, F, and cover faces 1 and 2 of the others ;

n—

Bo, . is the number of arrangements in which A, B, C show face 1, and D, E, F
face 2.

6.0.45 0 6.201
Hence {oan oS C2
is the number of arrangements in which A, B, C, D, E, F have faces 1 and 2

| tripled; consequently

665.469. 2 vl p (p=) gr-s
(OGG) een ee 2

362 PROFESSOR KELLAND ON A PROBLEM IN COMBINATIONS.

is the number in which A, B, C, D, E, F form two triplets. Hence the number
of arrangements in which there are two triplets, and no more, is—

n(n—1)....(n—5) 6.5....1p(p—l) gts
iW Pee (1.2.3)? 1.2 “r-3
_ m(m—l)... -(m— ae O
(1.2.39 os
9. The whole number of arrangements in which no quadruplication occurs is—

nn (n—1) (n—2 n—3 n(n—1). 5 mp Ae n—6
cs oo teem “o-3

n (n— og se 8) p (p- see Js 2) C'S + &e.

10. In the same manner it may be shown, aed if the above series be repre-
sented by dD’, the whole number of arrangements in which no quintuplications
occur is—

n nm(n—1) (n—2) (n—8)

D, + pD- n(n—1)....(n—7) , — -1) DE. + &e.

1.2.3.4 eat (1.2.3.4 oy ee

11. It is evident that the total number of arrangements of the faces is p”.
Hence the probability that no two show the same face is—

Pera een petty
pe

Geer

XXIV. On Solar Light, and on a Simple Photometer. By Muneo Ponton, Esq..,
F.R.S.E.

(Read 4th March 1856.)

In approaching the subject of solar light, the first point is to endeavour to
form an idea, not altogether indefinite, with respect to its quantity and intensity,
as compared with some familiar standard of artificial flame. With this view
were made, in the course of last summer, the observations now to be described.

After several trials, it was found, that the most convenient mode of procedure
was first to compare a definite small surface, illuminated by solar light, with a
like surface illuminated by the mere light of the sky, and then to compare the
latter with a similar surface illuminated by the flame of a moderator lamp.
The light of the sky thus affords a middle term between the extreme lights of the
sun and the lamp, which are too diverse to be directly compared.

The first difficulty to be overcome, was that arising from the difference of
colour between the flame of the lamp and the light of the sky. For this purpose,
it was found necessary to employ light of only one colour; and blue light was
selected, as that which could be most easily obtained pure.

Various methods having been tried, it was found that the blue rays could be
obtained in sufficient purity, by taking the common blue paper used by haber-
dashers for packing their light goods, and steeping it in a concentrated solution
of sulphate of copper, and then viewing this paper through common blue glass.
This glass, it is well known, transmits only the blue rays and the extreme red;
_ but the blue paper absorbs the extreme red, and disperses only the blue and a
_ few yellow rays, which last are absorbed by the blue glass; so that, by this com-
| bination, only the blue rays reach the eye. In the light thus obtained, no rays
_ save the blue could be detected by prismatic analysis.
| To regulate with exactness the quantity of light admitted to the eye, a num-
| ber of small slips of tea-lead were perforated with holes of various diameters, from
| goth down to ;4,th of an inch. These apertures were carefully made, the rugged
| edges being removed, so as to present a clean circular outline. The diameter of
| each hole was exactly measured under the microscope, with a power of a hun-
_ dred diameters.

The next point was to secure the exclusion from the eye of all extraneous light.
| For this purpose two pasteboard tubes were made, about eight inches long, and
‘one inch in diameter, and lined inside with dull black paper. These were placed
parallel to each other, and fastened together in such a manner that the centres
VOL. XXI. PART III. oF

364 M. PONTON, ESQ., ON SOLAR LIGHT,

of their diameters were two-and-a-half inches apart, but with the means of
slightly varying this distance, so as to bring the apertures exactly opposite the
pupils of the two eyes. At the end of the tubes next the eye was an aperture of
about a quarter of an inch in diameter, in which was inserted a piece of blue
glass. Outside of these were placed slides, into which the perforated slips of lead
might be introduced, in such a manner as to prevent their apertures from touch-
ing the surface of the paper, for fear of the entrance of minute fibres. At the
ends of the tubes farthest from the eyes were simple apertures of about a quarter
of an inch in diameter. To each of these farthest ends was attached, at the inner
edge, a piece of card, which, after projecting outwards, about an inch and a half,
was bent round at a right angle, so as to face the end of the tube. ‘These pieces
of card were covered on the outside with black paper, and on the inside with
the prepared blue paper before described. The lower part of the card was at-
tached to the lower end of the tube by a similar piece of card, also lined with the
blue paper; and there was thus formed, at the further end of each tube, a small
rectangular box, open at the top and the outer side, and lined throughout with
the blue paper. To each of these boxes were closely fitted covers, which could
be put on and removed at pleasure. The cross piece connecting the two tubes
was fastened to a telescope stand, so as to'place the tubes horizontally at the level
of the eyes. When so adjusted, the surfaces destined to receive the light were
vertical.

In Plaie VIII. fig. 1, is shown a bird’s-eye view of the two tubes PQ and RS;
while XY is the cross piece by which they are attached, and on which they
slide horizontally, so as to adjust their distance ; ¢¢ are the ends next the eyes,
and cc, cc are the cards fastened to the farther ends, on which the light is to
fall. Fig. 2 is a central cross-section, showing how the tubes are connected by
the cross piece, and the latter with the telescope stand T. Fig. 3 shows the two
ends next the eyes, with the perforated slips of lead inserted in the slides. ©
Fig. 4 shows the farther end of the tube, prepared to receive the sun-light, with
the direction of the rays 77". Fig. 5 shows the farther end of the other tube, fur- _
nished with a small screen s to exclude the direct rays of the sun, and leave the
receiving surface illuminated by the mere light of the sky. Fig. 6 shows the —
end of the sun-tube, disposed for the lamp; the ring / being the argand burner,
surrounded by a screen ss to confine the light. This screen was covered with —
black paper outside, and lined with white paper inside, so as to give the lamp-
light the benefit of its reflection. There was another screen, not shown in the
figure, placed over the argand, with a hole only sufficient to admit the glass chim- —
ney. By this arrangement, all light was excluded from the little box, except —
that of the lamp, whose flame was placed in such a position that the rays fell on
the receiving surface at a horizontal angle of about 45 degrees, the surface of
the flame being about two inches from the receiving surface.

AND ON A SIMPLE PHOTOMETER. 365

When this instrument had both its receiving surfaces lighted by mere day-
light, there were seen, on looking through it with both eyes, two equal round
spots, one-fourth of an inch in diameter, of a very pure blue colour. If the aper-
tures next the eyes were equal, these spots appeared of exactly the same tint and
intensity; but if one of the apertures was a very little smaller than the other,
the spot, viewed through the smaller aperture, appeared of a sensibly darker
shade, in so much as to impress the eye with an idea of difference of colour.
This peculiarity greatly aids the eye in judging when the two spots are of exactly
equal brightness. It is, of course, necessary to take care that both apertures are
smaller than the pupil of the eye.

In order to determine how far the results to be obtained by this instrument
might be found to agree with those which may be obtained from the method of
equal shadows, the instrument was first employed to compare the light of the
moderator lamp with that of a wax candle (a short 6); and, after repeated trials,
it was found that the results of the comparison, when made with this instrument,
exactly agreed with those obtained by the method of equal shadows, the light of
the lamp proving to be 33 times that of the candle. Indeed it is, if anything,
easier to judge of the perfect equality in brightness of the two blue spots, than of
the equal darkness of two shadows.

Several preliminary trials were next made, with a view to obtain a series of
approximations to the relative sizes of the apertures tobe employed. In making
these observations, the observer should sit in an easy, half-reclining posture, with
his back to the sun, so as to have the receiving surface exactly opposite to that
luminary ; his elbows should be rested steadily on the table; and his hands placed
at the sides of his eyes, to screen them from extraneous light. Before looking
into the instrument, the eyes should be closed for a little time, to render them
more sensitive to the feeble blue rays; and care must be taken to have the two
images simultaneously visible without effort, so as to admit of their exact compa-
rison. For a good observation, a bright, cloudless, and perfectly calm day,
should be chosen; and the sun should be at an altitude of about 45°, so as to
give the mean brilliancy of sunshine.

Thursday the 10th of August 1855 having proved entirely suited for the pur-
pose, advantage was taken of it, to make the decisive observations, which were
commenced about 11 a.m., and occupied between 15 and 20 minutes.

The diameter of the aperture fitted to the sky-tube was 0:083 inch. The sun-
tube was tried first with an aperture of 0-015, through which the sun-lit surface
appeared a little brighter than that lighted by the sky. It was next tried with an
aperture of 0:01375, and then the sky-lit surface appeared the brighter of the
’ two. Lastly, there was applied to the sun-tube an aperture of 0:014875, and
then no appreciable difference could be detected by the most steady gaze. These
three apertures were changed several times, and always with the same results.

366 M. PONTON, ESQ., ON SOLAR LIGHT,

The little box at the end of the sun-tube had now its cover put on, so as to
leave open only its right-hand side, to which the lamp was approached, and dis-
posed in the manner before described. The aperture applied to this tube was
now 0-1, and, after trying several approximate apertures for the sky-tube, one
of 0:0275 was ultimately fixed upon, as that which rendered the two images of
exactly equal brightness.

These observations were subsequently repeated, with the same results ; and,
on each occasion, the apertures were, after the observations, examined under the
microscope and ascertained to be clear. These results may therefore be regarded
as a fair approximation to the truth.

The brightness of the images being inversely as the areas of the apertures,
it follows from the first observation, that a small surface illuminated by the
direct rays of the sun at an altitude of 45° is 33:6 times brighter than a similar
surface illuminated by diffuse day-light; while, from the second observation, it
follows that a like surface illuminated by the flame of a moderator lamp, at the
distance of 2 inches, and placed obliquely so that the rays might fall as nearly as
possible at a horizontal angle of 45°, is 13:2 times less bright than a similar
surface illuminated by diffuse day-light. Hence, the same surface when lighted
by the sun is 444 times brighter than when lighted by the lamp, under the above
circumstances, the blue rays only being used in each case. This exclusion of all
but the blue rays, is somewhat adverse to the artificial light, which has an excess
of red and yellow rays, beyond what is required for the composition of white
light; but the blue rays may be held to indicate the proportion of white light,
contained in the artificial flame.

As, from the preliminary observation, it was found, that the moderator lamp
employed was 3°5 times brighter than a wax candle (short 6 in the lb.), it fol-
lows, that a small surface, illuminated by mean sunshine, is 1554, or say 1560
times brighter than is the same surface when lit by such a wax candle placed
at 2 inches from it, in an oblique direction.

Now, it is found not difficult to raise the electric light to such a pitch of in-
tensity as to afford a light equal to that of 520 wax candles; so that, if the
moderator lamp were replaced by three such electric lights, the surface would be
equally bright as when illuminated by mean sunshine.

To form a conception, therefore, of the quantity and intensity of the light
emanating from the sun, when it reaches a distance of 95 millions of miles from
his centre, we may imagine the surface of a sphere, having that distance for its
radius, to be covered all over with a very thin film, say zog9th of an inch in thick-
ness, having a brightness equal to that of an electric light of the above-mentioned —
intensity, and that behind this there are two similar films of equal brilliancy,
the three forming a thin stratum, say goth of an inch in thickness; then such a
stratum would represent the brilliancy of the sun’s light at the earth’s orbit.

AND ON A SIMPLE PHOTOMETER. 367

Now, let us imagine this stratum to be transferred to the surface of the sun.
_ It would there be spread over 46,275 times less area; consequently, its thickness
would be increased that number of times, and would therefore amount to about
1182 inches, or about 94 feet, embracing 138,825 layers of flame, equal in bright-
ness to an electric light of the above-mentioned intensity, and it would at its
outer surface possess a brilliancy equal to that of the surface of the sun.

It is evident, however, that there might be a very considerable addition made
to the thickness of such a stratum, without affecting, in any appreciable degree,
its proportion to the planetary distances. If then, the thickness of the stratum
were increased 520 times, making it 49,000 feet, then it might embrace 72,000,000
layers, each of them having an individual brilliancy not greater than that of a
wax candle. The real thickness of the stratum in which the luminous property
of the sun resides, may be very considerably greater than the above estimate,
which is somewhat over 9 miles; and the luminosity of each individual film com-
posing the stratum may he very considerably less, without affecting the general
result.

VOL. XXI. PART III. oOo G

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( 369 )

XXV.—On the Possibility of combining two or more Probabilities of the same Event,
so as to form one Definite Probability. By the Right Rev. Bishop Terror.

(Read 17th March 1856.)

(1.) The inquiry which, with its results, I propose to lay before the Society,
was suggested by the following passage in the very popular Treatise on Logic by
Dr WHATELY, now Archbishop of Dublin.

«‘ As in the case of two probable premises, the conclusion is not established
except upon the supposition of their being both true, so in the case of two (and
the like holds good with any number) distinct and independent indications of the
truth of some proposition, unless both of them fazl, the proposition must be true:
we therefore multiply together the fractions indicating the probability of the
failure of each—the chances against it—and the result being the total chances
against the establishment of the conclusion by these arguments, this fraction be-
ing deducted from unity, the remainder gives the probability for it.

« #. g. A certain book is conjectured to be by such and such an author, partly,
1st, from its resemblance in style to his known works; partly, 2d, from its being
attributed to him by some one likely to be pretty well informed. Let the proba-
bility of the conclusion, as deduced from one of these arguments by itself, be sup-
posed 2 and in the other case = then the opposite probabilities will be respec-
12
30
conclusion ; 7. ¢., the chance that the work may not be his, notwithstanding the
reasons for believing that it is; and, consequently, the probability in favour of

tively 3 and mn which multiplied together give = as the probability against the

the conclusion will be ae or nearly = (WuateELy’s Logic, 8th Ed., p. 211.)

(2.) Now, this reasoning appears to me erroneous, because it can be so applied
as to bring out two inconsistent conclusions. It must be observed, that there is
no such generic difference between the chances for and against the truth of a pro-
position, as can require or justify any difference in the laws and methods applied
to them. A negative can always be turned into an affirmative by a change of
verbal expression, without any change of meaning. Thus the chance of not hit-
ting a mark is the same as the chance of missing it. The chance of a life not fall-
ing before sixty, is the chance of its continuance up to sixty. The chance that A
was not the author of the book, is the chance that some one else was the author.

Let us then take as the proposition whose probability is to be found, the negative

—he did not write it—the partial probabiilties for which are by the data - and ss

VOL. XXI. PART II. 5 H

370 BISHOP TERROT ON PROBABILITIES.

: Sane 2 3 ; :
The opposite probabilities are now = and 7 and their product is = the probability
against the conclusion whose probability we are now seeking. Consequently,
ae ze is the probability for our conclusion, namely, that he did not write the

book. But by the former calculation, the probability of the same conclusion was

t=

found to be = and, as these incompatible results follow from the same principle

and method, the principle and method must be erroneous.

(3.) The only mathematical attempt at the solution of this problem which I
have met with, is at section 15 of the Article Probability, in the Encyclopedia
Metropolitana. It is given there as follows :—

“It is an even chance that A is B, and the same that B is C ; and, therefore,
1 to 3 on these grounds alone, that Ais C. But other considerations of them-
selves give an even chance that Ais C. What is the resulting degree of evidence
(or the probability) that A is C?” There is a previous solution which I omit, and
then the passage proceeds as follows :—“ Let us now treat the preceding question
as having two contingencies, the compound argument 1 to 3 for, and the inde-
pendent evidence an even chance. We have, therefore, four possible cases.

Pros. A is C.

; 1 ate AS omedindl

“ Aroument and Evidence both true, ace
. Bes) hy oad

Argument false, Evidence true, ao ote

j 1 1 i ge

Argument true, Evidence false, aX g=%

Argument and Evidence both false, : : = 0
‘““The sum of these is : as before (for the resulting probability that A is C).

The above generalized is as follows:—Let @ and (1—qa) be the probabilities for
and against the argument (the conclusion from the argument); and € and (1—e)
be the probabilities from any other source. Then the chance that both are wrong
is (l—a) . (1—e), and of the contradictory, namely, that (A is C) follows from the
one or the other, is 1—(1—a). (l—€)=a+e-a €.”

This is the formula adopted by WuareELy; and it is open to the same objec-
tion, namely, that by applying it we can arrive at two contradictory conclusions.
But, further than this, what is the meaning of Argument true, Evidence true?
The argument and the evidence are here treated as two independent events hay-

1

ing respectively the probabilities of = and 5; and their coincidence is represented

by = But nothing corresponding to this goes forward inthe mind. The argument

merely affords the information, that for every reason for believing that A is C, there
are three equivalent reasons for believing that A is not C. This information we

BISHOP TERROT ON PROBABILITIES. 371

are supposed to believe absolutely; there is no question as to the probability of
its truth, or the possibility of its falsehood. The only matter in question is
whether A is C, or is not C.

The falsity of the expression a+¢—a ¢ will be evident, if we give to a and ¢

2 2 CuUibS 80 ‘ es
the values z and - Then a+e—ae= z +7 —qo=gtqq That is to say, while

each of the independent probabilities is less than :

5? and, therefore, in favour of

the negative, their compound force is much above ; ; and, therefore, in favour of
the affirmative. If then we found from internal evidence and external evidence
severally. that the chances were against the truth of the proposition A is C, we
ought to conclude from their united force, that the chances are in favour of the
proposition. But the human mind is incapable of coming to such a conclusion.

It may be well to notice in passing, that the problem under consideration is
altogether different from that of finding the compound force of two identical as-
sertions made by two witnesses, whose veracity, that is, the probability of their
speaking truth, is expressed by « and e. In that problem, we possess among the
data the fact, that each witness makes the same assertion. But in the problem
we have been considering, there is no such assertion. Neither the argument nor
the evidence assert or deny that A is C. What they give as data, is merely that
the reasons for believing that A is C, are in a given ratio to those for believing
that A isnot C. And as the data of the two problems are of totally different
character, the methods to be applied must of course be different. I have men-
tioned this, because some good mathematicians whom I have consulted, were at
a €

first disposed to consider —— as the proper expression for the con-

aé+l—a. 1—e
joined force of the argument and evidence.

(4.) Let us now consider the Problem under the following form. A, whose veracity
is undoubted, states that, from his knowledge of the facts of the case, the probability

of the event E is B, under the same conditions, states, that it is = Supposing

the facts known by each to be altogether distinct, what is the proper measure of the
expectation formed in a third mind by these tivo statements ?

(5.) Before attempting to show how a solution of the problem ought to be
sought, it may be well to observe, that the mind cannot admit two probabilities
of the same event as co-existent probabilities. Thus, if A tells me that the proba-

bility of rain to-morrow is = and B that it is I cannot admit both of these as

probabilities; for that would be equivalent to believing on the authority of A,
that it is Jess likely to rain than not, and at the same time to believe on the
authority of B, that it is more likely to rain than not.

What really takes place is this. The two fractions are received as indications

372 BISHOP TERROT ON PROBABILITIES.

of the effects reasonably produced upon the minds of the informants, by the know-
ledge of certain facts which they have not communicated to us. The fractions
which they give are admitted as true exponents of the results of their respective
partial knowledge, no doubt resting either upon their veracity, or upon the accu-
racy of their inferences. We admit, that each states the probability as he ought,
under his circumstances: and the question is, how ought we to state it under our
circumstances, knowing as we do something more, and also something /ess than
either of our informants.

(6.) In attempting to answer this question, I shall have recourse to the ordi-
nary illustration of an urn and balls. Let us suppose that A has seen p white
and q—p black balls introduced into an urn, which he believes to have been pre-
viously empty. He properly infers that the probability of drawing a white is
7 B, under the same circumstances, has seen 7 white, and s—7 black balls in-

troduced, and infers that the probability of drawing a white is . If they com-

municate to each other only their znferences, there is an apparent contradiction,
and no combination or agreement can take place. But if they communicate the
facts from which the inferences were deduced, then each knows that the urn con-
tains p+7 white, and g+s—p—r black balls, and agree in making the probability of

+r

drawing a white a ;,: ifthe number of balls whose introduction has been seen

by the two observers be equal, then © anaes =e ¢ +7) = is the sum of the
qts 29» 2\gi 2

several probabilities.

P.

It may be observed that oe as the expression of the combined probabilities

E and z, is not exposed to the objection of admitting contradictory results, for,

if we take the negative as the conclusion whose probability is to be found, then
A gives for the probability of the conclusion 1 = = ee while B gives 1— one f.
Ss
q—pt+s—r
Wigeie a4 But the
a and cee gts
qts qts qt+s qts

therefore the combined probability against the event is

combined probability for the event was

=], asi

ought to be.
(7.) But what we have to consider, is the impression made upon the mind of
a third person, who is informed by A that, from his observation, the probability

of drawing a white is ? and by B that, from his observation, it is -, and to

whom no farther information is given, except that the observations were totally
distinct. Now, as these data give only the ratio of white to black balls at each
introduction, there may have been, in the first, » white and g—p black, or there

— wes 2.

BISHOP TERROT ON PROBABILITIES. 373

may have been 2p white and x q—mp black, where n is any whole number from
one to infinity. In like manner, the second may have consisted of m7 white
and ns—nr black, where 7 is any number from one to infinity. Any one as-
sumed state of the first introduction may have co-existed with any assumed state
of the second; and thus assuming that the first contained p white and q—p black,
we have the infinite series of probabilities,

ptr pt2r ptnr

q+s—p—r’ g+2s—p—Zr gqtns—p—nr~
Again, assuming that the first contained 2p white, and 2 g—2p black, we have

2p+r 2p+2r 2p+nr
2qts—2Qp—r’? 2q4+2s—Zp—Br- 2qtns—2p—nr’
and so on ad infinitum.
This infinite series of infinite series I cannot sum. If they can be summed,
then their sum divided by the infinite of the second order n’, is the probability

required.

Lr 5
In no case, except when eae so far as I see, can the sum of their sums, or

the whole probability, be determinately expressed. When ar the fractions being

in their lowest terms, p=7 and g=s. The two pieces of information are then
identical; the same information is given by both observers; and the information,
unaffected by the repetition, is absolutely received by the third party: and this
is the result, if, in the foregoing series, we substitute p for r and q for s.

(8.) If we revert to the expression (3) given in the Encyclopedia Metropoli-
tana, where the separate probabilities are @ and e, and their conjoint force is
stated to be a+ «—ae, it would follow that the effect produced by two observers
making the same statement as to the probability of an event should be twice the
asserted probability mznus its square. Now, in the case of a repetition of the
same probability by two observers, it must, I think, be allowed that my result is
conformable to that of which we are all conscious. If, for example, the North-

ampton and the Carlisle Tables both give 5 as the probability that a man of

thirty will live to the age of fifty, and are both implicitly believed, we believe that
there is an even chance of his living to fifty, and not, as would follow from the
expression given in the Encyclopeedia, that the chances are three to one in his
favour.

(9.) It perhaps deserves to be noticed, that when a second series of observa-
tions or experiments is added to one previously admitted, the probability is not
increased by the mere preponderance of favourable over unfavourable cases in
the second series. To increase the probability, the ratio of favourable to unfavour-
able cases must be greater in the second series than in the first. For the first

received probability is A and the composite is ae (6.)

VOL. XXI. PART III. ae

374 BISHOP TERROT ON PROBABILITIES.

Now pares when rq> sp, Or rq-rp > SP—T Pp,

a oP
or r(q—p) >p.(s—r)s OP ee

When the ratios only are given, any conceivable case of the grounds upon
which the probabilities are given may be represented by mp, mq, nr, and ns.
Hence the original probability is “~” , the composite is mPT"? and this is greater

mg MY+NS

than ales when
mY

mpqtmngr >m pqtmnps
or rg > ps, as before.

(10.) Valid objections may, I think, be made to the last paragraph’of the sec-
tion in the Encyclopedia already referred to. As this is not long, I quote it en-
tire. ‘The following theorem will be readily admitted on its own evidence. Jf
any assertion appear neither likely nor unlikely in itself, then any logical argument
in its favour, however weak the premises, makes tt in some degree more likely than
not. In the manner in which writers on Logic apply the calculus of probabilities,
this is never the consequence of their suppositions. For what we have called a
is their resulting probability of the argument. Suppose, for instance, a writer

on logic presumed that the argument from analogy gave = to the probability

that there is vegetation in the planets, which must be regarded as a thing neither
likely nor unlikely in regard of evidence from any other source, he would take

= to be the probability of this result, that is, less after an argument in its favour

spi ; Un cdo, Seale
than it was before. We substitute 5+5 . 7>=59°

This numerical equation is the value of the expression (4+¢—a6), when

1 3
a= 5€ = 7,5: I have already shown that this expression does not truly represent

the composite force of the two probabilities @ and e. But farther than this, the

argument from analogy, giving _ as the probability of the affirmative, is an

argument, not 2m favour of, but against the proposition that there is vegetation
in the planets. It implies that for every three reasons for believing that there és,
there are seven for believing that there és not ; and, consequently, the effect of
the argument ought to be to diminish our disposition to believe the proposition,
or, in other words, to diminish its probability.

(11.) But it may be worth while to examine whether the fraction 2 be, after

all, a true available expression for the probability of an event, which is neither

likely nor unlikely to happen, or to have happened, there being no evidence, no
reasons for belief, either for or against it.

BISHOP TERROT ON PROBABILITIES. 370

Probability, as Mr Boots in his Laws of Thought, properly defines it, is “‘ Ex-
pectation founded upon partial knowledge.” Events, therefore, of which we
possess complete knowledge, and events of which we possess no knowledge, are
equally, by the terms of the definition, excluded from the class of probable events,
that is to say, of events to which the calculus of probabilities can be applied. If
we are certain that an event has happened, we totally neglect and are unaffected
by any subsequent information, which, but for that certainty, would have given
to the event a definite probability expressed by a proper fraction; and never
think of looking for a form by which to combine such fraction with the unit ex-
pressing the certainty. If, again, we derive from experience or observation a
definite probability of any event, such, forexample, as the probability for drawing
a white ball from an urn, whose contents are given; namely, the fraction whose
numerator is the number of white balls, and its denominator the total number of

balls contained, we never think of combining this with the : which is assumed

as the probability when nothing whatever was known, except that the ball drawn
must be either white or not white. Complete knowledge comprehends all pre-
vious partial knowledge; and, therefore, all fractional expressions for probability
derived from the latter, are virtually contained in the unit, which is the expres-
sion adopted for the certainty produced by the former. On the other hand,
partial knowledge destroys total ignorance, and any inference that may be drawn
from it. It comprehends the hypothesis that the event may, and that it may not
happen, with a definite probability to each, which do not supplement but super-

sede the probabilities of : previously assumed foreach. I cannot conclude without

suggesting a doubt, whether : be at any time the proper expression for the pro-

bability of an event which is “neither likely nor unlikely in regard of evidence.”
It seems more analogous with the practice in other cases to express such pro-

bability by the indefinite fraction °. Tf this expression be applied to either of the

0
probabilities constituting the compound probability i =, the compound proba-
bility will be reduced to the remaining simple probability, for = == And this

agrees with the necessary action of the mind, which takes no note of its original
ignorance, after it has arrived at a definite probability from partial knowledge.

(12.) Hitherto, I have been speaking of the combined result of two probabilities
of the same event, derived from distinct sources of partial knowledge; and Ihave
shown that to obtain a definite result, the mere ratio in such case is insufficient,
and that the actual number of favourable and unfavourable cases in each of the
data is requisite.

376 BISHOP TERROT ON PROBABILITIES.

But when the given probabilities are of different events, and the queesitum is
the probability of their joint occurrence, the ratio alone is sufficient, because as
factors “” and “2 give the same results.

mq ng

(13.) To sum up the propositions proved in the foregoing paper :—

1. If the ratio only of equally probable cases, in two or more probabilities for
the same event be given, no definite probability can be derived from their compo-
sition. (7.)

2. If the two given probabilities ? _ indicate not merely the ratio, but also

the actual number of favourable and unfavourable hypotheses or cases, their con-

joined force is properly expressed by 5 — (6.)

3. Under both of these conditions, the second given probability increases or
diminishes the force of the first, according as the fraction expressing the second
is greater or less than that expressing the first. When the ratios only are given,
then the extent of increase or diminution is indefinite. When the actual numbers
are given, it is definite. (9.)

4. The a priori probability derived from absolute ignorance has no effect
upon the force of a subsequently admitted probability. (11, 12.)

(377)

XXVI.— Researches on Chinoline and its Homologues. By C. GREVILLE WILLIAMS,
Assistant to Dr ANDERSON, University of Glasgow.

(Read 7th April 1856.)

Twenty-two years have now elapsed, since Runcs first published his remark_
able experiments on coal naphtha,* and it would, perhaps, be difficult to instance
any chemical investigation which has formed the point of departure of a greater
number of researches. When we consider the vast quantity of bodies which have,
first and last, been obtained from coal-tar, it might appear that little more
remained to be done,—that the mine was exhausted,—but so far from this being
the case, the discovery of one substance has only served to pave the way for the
isolation of others.

Among the bodies examined by Runes, there was one which apparently pos-
sessed comparatively few features of interest ; indeed its very name (the first syl-
lable derived from A«xé;) was intended to express its supposed inability to produce
coloured reactions, a feature which, in the chemistry of the time, militated greatly
against its claims to notice. I have used the expression “ supposed inability,” be-
cause I shall show further on, that this substance is capable, under certain condi-
tions, of affording extremely brilliant colorations. Eventually, Gernarpt,} by
acting on quinine, cinchonine, and strychnine, with hydrate of potash, obtained the
samebody. The first chemist who succeeded in procuring any of its compounds in
a state of tolerable purity was Hormann, whose analysis of the platinum salt is
very nearly exact. But, at the time of that analysis, he was of opinion that the
products obtained from coal and chinoline were essentially different, an opinion
which he subsequently retracted. In the mean time, the alkaloid, as obtained
from cinchonine was examined by Bromets{ and Laurent, their results, how-
ever, not elucidating the composition of the basic fluid obtained in the manner
alluded to.

Some time since, I undertook the examination of the bases produced by de-
structive distillation of the bituminous shale of Dorsetshire, and found them to
be identical with those from bone-oil.|| I now began to see the great probability
that all processes of destructive distillation of nitrogenous matter at very elevated.

. * Pogcenp. Annal., Bd. xxxi., p. 65 und 513; und Bd. xxxii., p. 308 und 328.
+ Revue Scientif., x., 186. Compt. Rend, des Tray. de Chim. 1845, p. 30.
+ Liesie’s Annal., Bd. li., p. 180; and Ann. der Chem, u. Pharm. li, 130.
§ Ann. de Chim. et de Phys. [3] xxx., 368.
|| Quart. Jour. Chem. Soc. Lond., July 1854.

VOL. XXI. PART III. 5K

378 MR C. G. WILLIAMS’ RESEARCHES ON

temperatures would result in the formation of the same classes of alkaloids, and
subsequent researches* have only tended to confirm this view. Ina little paper,
“ On some of the basic constituents of Coal-Naphtha, and on Chryséne,”} I have
given a table, showing the extraordinary similarity of the basic products derived
by dry distillation from Dirret’s oil, coal, the Dorset shale, and cinchonine. The
last of these researches was undertaken in the endeavour to throw light upon the
discrepancies in the results of the chemists who had previously examined chino-
line, the experiments being embodied in a paper which appeared in the Transac-
tions of the Society last year. In that communication,t I showed that the fiuid
usually known as chinoline, and supposed to have the formula C,, H, N, had, in
fact, a very complex constitution, and contained in addition to that base, six
others. As my chief object at that time, was to demonstrate the real nature of
the decomposition which cinchonine undergoes at an elevated temperature in the
presence of alkalies, I did not make a minute examination of the chinoline itself,
as I conceived it to be sufficient for the purposes of that investigation to show
that a base of the formula C,, H, N did really exist in the fluid. This fact was
by no means a matter of course, for the analyses of the chinoline from cinchonine
previously published were so conflicting, that it was a difficult matter to derive a
formula from them. Hormann’s analyses were made upon a product from coal-
tar, and the formula he gave as the expression of his results, was C,, H, N. But
as an even number of atoms of hydrogen in a body containing an equivalent of
nitrogen, was incompatible with views now almost universally received of the
constitution of organic bodies, C,, H, N was taken by most chemists as the true
formula of the base from coal-tar. But the wide differences in the analyses of
the chinoline obtained by distilling cinchonine with potash, induced GERHARDT §
to express doubts, as to whether C,, H, N, or C,, H, N was the correct formula,
although he appears to lean towards the latter, for he places it at the head of the
section, but, nevertheless, shows that the formula is open to doubt, by annexing
a note of interrogation to it. I have shown the cause of the variable nature of
the results obtained by other experimenters, and have proved the existence of a
homologous series, of which, until I commenced this investigation, only one mem-
ber was known.

Many circumstances conspire to render a detailed examination of chinoline a
problem of interest, for, perhaps, no other body, known for an equal length of time,
and investigated by so many hands, is so erroneously described in the manuals
of organic chemistry. In fact, there are few things stated regarding it, that are
not more or less incorrect.

* I take this opportunity of expressing my sense of Dr Anprrson’s kindness, in permitting me
to make use-of his laboratory and apparatus, during my endeavours to realize this idea.

+ Chem. Gazette, Nov. 1, 1855; and Edin. Phil. Jour., Oct. 1855.

+ Trans. Roy. Soc. Edin., vol. xxi., part ii.
§ Traité de Chimie Organique, troisiéme partie, p. 148.

i eM i Ae

_——s =.

CHINOLINE AND ITS HOMOLOGUES. 379

Chinoline has, however, been invested with an artificial interest, from a sup-
posed intimate connexion between it and quinine, and an equally supposititious
parallelism between the action of heat upon the last named alkaloid, and upon
the hydrated oxide of tetramethylammonium, while the real points of attraction
which it possesses have been neglected, or supposed not to exist.

The first incorrect idea of the connexion between chinoline and quinine, may
be very briefly disposed of. It was founded upon the supposition that chinoline
was the sole product of the action of hydrate of potash, at a high temperature.
upon quinine. In this manner, it was easy to construct an equation by which it
was made to appear, that quinine, m2nws a certain number of equivalents of car-
bon, hydrogen, and oxygen, yielded chinoline.

Another supposed connexion between the two alkaloids was a very beautiful
one, and one that, at the time when C,, H, N was the received formula for chino-
line, could scarcely have failed to suggest itself to the eminent chemist, whose
particular train of research led him to examine the action of iodide of methyl
upon the natural and artificial alkaloids. It is well known, that iodide of tetre-
thylammonium, by treatment with oxide of silver, yields hydrated oxide of that
base, which is rendered obvious, by a glance at the following equation :—

0, H, C, H,

N CA n° I+Ag 0+HO=N I i | 0,HO+AgI;
C, H,
and if we follow out the same equation, substituting iodide of methyl]-chinoline-
ammonium,* for iodide of tetrethylammonium, we find that at first sight,
C,, H,, N, 1+ Ag 0+ HO=C,, H,, NO,+Ag I
cuaigs TE Ceo Dene?

Car eS

Todide of Methyl- Quinine.
_chinolineammo-
nium,

appears a reaction likely to take place;} unfortunately, however, there are two
reasons why it is impossible, the first being, that iodide of methyl-chinoline-ammo-
nium is represented by C,, H,, N, I, instead of C,, H,, N, I; and the other, that
the action of oxide of silver upon the methyl and ethyl compounds of the
nitryl bases of this class is more complex than would be supposed from the first
equation, and the known success of the reaction with the iodides of the ammonium
bases derived from the alcohol radicals alone.

So much has been said about the artificial formation of quinine from the leu-
kol of coal-tar, that I have appended a few reasons for concluding that it is im-
possible by any analogous process to that previously described. Quinine, accord-

* Supposing for the moment the old formula for chinoline (C,, H, N) to be correct.

{ I have vainly searched through the Chemical Journals for any paper by Dr Hormann, tending
to show the real nature of the action of oxide of silver upon iodide of methylchinoline, This has led
me to make the experiments detailed at page 392.

380 MR C. G. WILLIAMS’ RESEARCHES ON

ing to STRECKER’s experiments,* takes up only one equivalent of the alcohol
radicals, and is therefore concluded with safety to be a nitryl base. Chinoline
affords still more complete evidence of belonging to the same class, for not only
is it incapable of taking up more than one equivalent, but, by the operation, it be-
comes converted into a fixed alkaloid. Now, any process for making artificial
quinine by means of the reactions mentioned above, would result in the forma-
tion of an ammonium base, which must of necessity have a totally different con-
stitution to quinine. It may be worth while, for a moment, to glance at the for-
midable difficulties by which the artificial formation of such a base as quinine is
surrounded. In the first place, in the present state of our information, it appears
to consist of three radicals, united and having one equivalent of nitrogen and two
of oxygen attached. Now, to acquire a knowledge of the constitution of these
three radicals (one of which, in all probability, is oxidized) is a problem involving
a new mode of research, the key to which appears, for the present, to be hidden.
And even supposing the three radicals known, they have to be formed; and then
to combine them with the addition of an equivalent of nitrogen, without destroy-
ing the group, presents a task of no ordinary difficulty.

I should not have entered upon this branch of the subject, had it not been for
the manner in which the possibility of the formation of quinine, by the method
above alluded to, has been accepted as a reality, which is the more remarkable
from the manner in which HormMann cautioned chemists against placing too much
reliance upon the success of the process.

As it is my wish to correct, as far as my information will permit me, the
erroneous views which have been formed of the relations between chinoline and
quinine, I return to the supposed similarity between the action of heat upon qui-
nine and the hydrated oxide of tetramethylammonium. This part of the subject
is the more interesting, as it appears to have formed one of the links in the chain of
reasoning, which led to a belief in the possibility of converting leukol into quinine,
by the successive actions of iodide of methyl and oxide of silver. As the fixed
base, hydrated oxide of tetramethylammonium, by heating yields trimethylamine,
the difference being C, H, O,, so quinine, less C, H, O, yields the old formula of
leukol} thus,—

C, H,, NO,—C, H, 0,=C, H, N
—_

——_—SOoOC_
Hydrated Oxide Trimethyl-
of Tetramethyl- amine.

ammonium.
Cone NO, — C7 0, = Ci ihe
NE a
Quinine. Leukol.
The identity in kind of the above equations presupposes two conditions, neither
* Researches in Organic Chemistry, by ApotpH Strecker. Compt. Rend. xxxi. 49. Chem.

Soc., Quart. Jour. 1854, vol. vii, p. 278.
tT Quart. Jour, Chem. Soc., vol. iv., p. 328.

CHINOLINE AND ITS HOMOLOGUES. 381

of which exist, the first being the correctness of the old formula for chinoline (or
leukol), the second, its being the sole basic product in the distillate, from the
cinchona alkaloids.

The next prevalent error with regard to chinoline is, that its salts have less
tendency to crystallize than the generality of nitryl bases; whereas, in fact, the
reverse (with some exceptions) is the truth. I have seldom seen salts more
easy to crystallize than the nitrate, oxalate, and bichromate of chinoline, while its
double salts, with platinum, gold, palladium, uranium, and cadmium, are beauti-
ful substances, the same may be said of the iodides of the methyl, ethyl, and amyl
compounds. The erroneous idea alluded to arose from previous experimenters,
working on an impure substance.

The only means for determining the constitution of chinoline up to the present
time, has been Dr Hormann’s analysis of the platinum salt, from a base extracted
from coal-tar ; for the combustions of the base itself yet made, are very unsatis-
factory. Annexed are the results as yet obtained.*

Hormann. BRoMEIS. Cra INGE Cale

ca OO
Carbon, . , : 82°67 82°88 82°34 82:74 82-78 83-70 83:91
Hydrogen, : ‘ 6:56 6:25 6:10 6-11 5°88 5:41 6:29
Nitrogen, mm i, 11:28 ~ ae = 10-89 9:80
100-00 100-00

A glance at the above numbers shows that no conclusion can be drawn from
them; and when it is considered, that chinoline and lepidine only differ by ‘21 in
their percentage of carbon, it becomes evident, that careful analyses of the salts
of these bases are the only means by which their history and composition can be
rendered certain. The platinum salt of chinoline possesses characters which
render it peculiarly well adapted for this purpose, inasmuch as it differs totally
from the corresponding compound from the-Dippel and aniline series, in its great
insolubility. I therefore selected this compound as a means of ascertaining the
purity of the various fractions obtained in the course of the investigation, and
which were intended for conversion into the various salts described further on ;
sometimes I was contented with merely a platinum determination, at others, I
ascertained by combustion with chromate of lead, the percentage of carbon and
hydrogen, and in this manner, the analyses quoted below were obtained. In my
former paper, I gave the result of three combustions of the platinum salt of chino-
line, and three platinum determinations; the salts analysed were obtained from
fractions boiling at a somewhat lower temperature than those the details of the
analyses of which are given below. The following analyses were made with salts
obtained from fractions boiling about 460°, which is, probably, very nearly the
boiling point of chinoline.

* GeRHARDT, Traité, troisiéme partie, p. 149.
VOL. XXI. PART III. OL

382 MR C. G. WILLIAMS’ RESEARCHES ON

450° and 460° F, gave

8-900 grains of platinum-salt of chinoline from fractions eilkess between
10559 ~~... ~—_ carbonic acid and
2A191> oo, water and
6-235 ... platinum salt of chinoline, gave
1-827 =... platinum.
IL { 6057 —..._— platinum-salt of chinoline gave
L722 cox: oplatimum,
II. 5907 ... _ platinum-salt of chinoline gave
1-731 ... » platinum.
or, per cent.—
if II. III. Mean.
Carbon, : : 32°36 sap oon 32:36
Hydrogen, : : 2°74 Se. iss 2°74
Nitrogen, : ie vi:
Chlorine, : : sae see 308 isa
Platinum, : ‘ 29°30 29-26 29-30 29:29

In the following table, the result of all my analyses (including those in the
former paper) is compared with the numbers required by theory; the analysis just
quoted being the fourth in the series :—

As 1G G5 III. IV. sife alr Mean. Theory.

Carbon, . ; -31:935. 32°24 32:52 - 32°36 re aoe 32°26 32°19
Hydrogen, . 3:09 2°62 2°58 2°74 hee ae 2°76 2°39
Nitrogen,. . Lae &e an oe bet ae a3 4:17
Chlorine,. . ee 53 A Nae fn si ae 31°74
Platnum, . 29°44 29°30 29°60 29°30 29°40 29-26 29°38 29°51
100-00

It will be seen that there is a slight excess both in the carbon and hydrogen of
these analyses. This arises from the presence of a small quantity of lepidine, the
platinum salt of the two bases being too nearly of the same degree of solubility to
allow of separation by fractional crystallization. This source of error is much
lessened in the other salts, their formation, in most cases, being a process of puri-
fication. Platinochloride of chinoline is very sparingly soluble in cold water,
requiring 893 parts for solution at 60° F.

It is to be remembered, that all the chinoline compounds mentioned in this
paper were made from a base procured by distillation of cinchonine with potash,
the coal-chinoline requiring a tedious series of purifications, in addition to the
fractional distillations, before it could be obtained pure enough for conversion into
compounds fit for analysis. The platinum-salt is, however, more easily obtained
in a pure state from the coal bases, than most other compounds of this alkaloid.

In the following table, the mean result of my analyses of the platinum-salt of
chinoline is compared with those obtained by other observers,* whose numbers
have been recalculated according to the present atomic weight of carbon.

* GERHARDT, loc. cit,

CHINOLINE AND ITS HOMOLOGUES. * 383

HoFMANN. GERHARDT. BROMEIS. GREV. WILLIAMS.
nS EOD. —_—————— Mean.

Caleul.

Carbon, . 32:06 att 82°99 32:46 32°51 3e°31 33°42 33.33 82°26 32°19

Hydrogen, 2°58 ... 314 3:14 3:28 271 283 2-68 2°76 2°89

Nitrogen, ... ae 4°42 Jee gee 3°98 421 4:00 he 4:17

Chlorine, 30°96 oat ee Be sae ae ea ee ee ene 3 eA.
Blatinum, 29°27 29°11 27:80 28:08 27:69 28°23 28°34 28°81 29°38 29°51

100-00

Only the first of these analyses was made from a base extracted from coal-tar ;
all the others were obtained from chinoline, produced by destructive distillation of
cinchonine with potash.

LaurEN’, by mixing hot alcoholic solutions of hydrochlorate of chinoline and
bichloride of platinum, obtained, after twenty-four hours, fine yellow needles ; but.
on examination under the lens, it was found not to be a homogeneous crystalliza-
tion, for a small quantity of little grains had also deposited.* I have not found
that any observer, except myself, has subjected the bases produced from cincho-
nine to a systematic fractionation, before forming the platinum salt. The fraction
analysed by me had been rectified fourteen times, and was nearly constant be-
tween 460° and 470°.

Aurochloride of Chinoline.—The only account of this beautiful salt [ have
been able to find is in Dr Hormanwn’s paper, on the bases of coal-tar, where he
merely states, that it corresponds in colour and other properties with the gold
salt of aniline, but the latter appears} to be a yellow precipitate which rapidly
becomes brown in the air, and, therefore, differs considerably from the chinoline
salt, which is quite permanent under the same circumstances. As obtained by
me from a specimen of chinoline of considerable purity, it was in the form of
slender canary-yellow needles, sparingly soluble in cold water, and precipitating
instantly on the addition of a solution of terchloride of gold, to a moderately strong
solution of hydrochlorate of chinoline.

3°883 grains of aurochloride of chinoline dried at 212° gave, on ignition,
1625 ... of gold.

or, per cent.—

Experiment.

Theory.
(C,, H, N, HCi+ Au Cl,)
41°85 42°00
Palladiochloride of Chinoline.—Dr Hormann describes this salt in his paper.
previously quoted, as resembling that from aniline, but M. Mitiert states the

latter to be yellow ; 1 found, however, that when moderately concentrated solu-
tions of chloride of palladium and hydrochlorate of chinoline are mixed, a copious

* GeRHARDT, loc. cit., and Laurent, Ann. de Chim, et de Phys. [3] xxx., 368.
{ Geruarpr, Traité, tome troisiéme, p. 86. ¢{ Ann. der Ch. u. Pharm. Ixxxvi., 368.

384 MR C. G. WILLIAMS’ RESEARCHES ON

deposit of chestnut-brown crystals takes place. This salt is moderately soluble in
water. It requires a very strong heat to give pure metallic palladium.

{ 3°423 grains of palladiochloride of chinoline gave, on powerful ignition in a porcelain capsule,

‘725 ~~... ~— palladium.
or, per cent.—
Experiment. Theory.
(C,, H, N, HCl, + Pd Cl
See
21:18 20:96

Cadmium Salt Chinoline.—The experiments of Crort, and more especially Von
Haver, have shown that cadmium forms well-defined crystalline salts, with the
chlorides of the alkalies, alkaline earths, and the chloride of ammonium. Before I
became acquainted with the results of the latter chemist, I had been engaged in a
series of experiments made with a view of extending our knowledge of the double
salts formed by the hydrochlorates of the alkaloids with metallic chlorides. The
information at present in our possession on this subject is very limited. The only
salts of the class alluded to which have been analysed, are those formed with pla-
tinum, gold, palladium, and mercury. Now the salts of the latter metal vary
greatly in constitution, and are, moreover, somewhat troublesome to analyse. I
have, therefore, made a few experiments with a view to ascertain what other
metals than those mentioned above, yield chlorides capable of combining with
the alkaloids, to form well crystallized double salts. In the present communica-
tion, however, I only notice those formed by the chlorides of cadmium and
uranyl with chinoline.

When moderately concentrated solutions of hydrochlorate of chinoline and
chloride of cadmium are mixed, the fluid solidifies with rise of temperature to a
snow-white mass of crystals. If the solutions are not too strong, they are ob-
tained in the form of needles occupying a great bulk when in the mother liquor,
but shrinking very much when pressed. They are less soluble in alcohol; I
therefore used that fluid to wash them. The alcoholic washings, when kept for
some time, deposit needles, often an inch long, but so silky and fragile as to be
preserved of their original size with difficulty. They retain their colour perfectly,
and, with the exception of losing two equivalents of water of crystallization, are
quite unaltered by drying for a few hours at 212°. The salt volatilizes at a consi-
derably higher temperature, without residue. The quantity at my disposal was
very limited, and being, therefore, obliged to work on small quantities, I found it in-
convenient to estimate the cadmium as oxide by the usual process, as the carbonate
of cadmium, when precipitated from solutions containing chinoline at the boiling
heat, not only has a strong tendency to pass through the filter, but adheres to the
paper so strongly as to cause a loss of metal by reduction and volatilization dur-
ing incineration. The precipitate was too light to be collected by decantation.

ea eS OT ee ee

fo Be aad | Mi pee

CHINOLINE AND ITS HOMOLOGUES. 385

I obtained, however, an accurate result by precipitating with sulphuretted hydro-
gen, and collecting the sulphide of cadmium on a weighed filter.

Tole ea of cadmium salt, dried at 212°, gave
I 8:976 carbonic acid, and

1:765 water.
8°875 cadmium salt, dried at 212°, gave
10-053 carbonic acid, and
2-060 water.
III. 10534 +. cadmium salt, dried at 212°, treated by Pexicor’s process, gave
42295 ... nitrogen.
IV. 6-997 cadmium salt chinoline, dried at 212°, gave
2°885 sulphide cadmium.
II. Iii. IV. Mean. Calculation.
Carbon, 30°94 30°89 30°92 30:99 C,, 108
Hydrogen, . 2°48 2°58 aa 2°53 2:29 H, 8
Nitrogen, see 4:02 4:02 4:02 N 14
Chlorine, mon dae 30°56 Cl, 106°5
Cadmium, 32:07 32°07 32°14 Cd, 112
100-00 348-5

It is evident, therefore, that the formula for the salt dried at 212° is—
C,, H, N, HCl+2 CdCl.

Several examples of salts of the same constitution occur in inorganic chemistry,
some of which have been examined by M. Von Haver, who terms them chloro-
bicadmiates. The chinoline salt, if merely dried by exposure to the air, contains
two equivalents of water, for at 212° it loses 5:41 per cent.; theory requires 4:91.
The excess arises from a little moisture adhering somewhat tenaciously to the
crystals.

Hydrochlorate of Chinoline and Chloride of Uranyl.—If double carbonate of
uranium and ammonia, dissolved in hydrochloric acid, is added to a strong
solution of hydrochlorate of chinoline, the fluid rapidly becomes filled with short,
brilliant, yellow needles, and in a few minutes the whole fluid solidifies, so that
the vessel may be inverted without the contents escaping. From more dilute
solutions, prismatic crystals are deposited, sometimes of considerable size. The
salt is of a rich yellow colour, and is very soluble in water. It was quite free
from any trace of ammonia. The mother liquid was removed by washing with
alcohol. The quantity at my disposal was too small to allow of a complete exa-
mination of all its properties.

*
6°760 grains of uranium salt of chinoline, dried at 212°, gave
7900 carbonic acid, and

water.

uranium salt, dried at 212°, gave

chloride of silver.

VOL. XXI. PART III. 5M

386 MR C. G. WILLIAMS’ RESEARCHES ON

Experiment. Calculation,
ea ft ais SE a oS
Carbon, : ; 5 31:87 ea 32:05 Ca 108
Hydrogen, . ; : Ol tn Teiesk 2°37 H, 8
Nitrogen, . ; ‘ sa Nes 4:15 N 14
Chlorine, : : ‘ ate 20:97 21:07 Cl, 71
Uranium, . : : nee ie 35°61 Ur, 120
Oxygen, ; : ; sg Pp 4°75 0, 16
100-00 337

The formula—
C,, H, N, HCl, + (Ur, 0,) Cl,
appears, therefore, to be the correct expression of the analysis, and it agrees in
constitution with the anhydrous ammoniochloride of uranyl of Pexicor. It is
my intention to examine the double compounds of uranium with other organic
bases.

Binoxalate of Chinoline.—The great discrepancy in the results of RuNGE and
HoFrMANN with regard to the oxalate of chinoline, made me desirous of ascertain-
ing the nature of this salt. According to the former chemist, leukol (chinoline)
has such a great tendency to form a crystalline oxalate, that this property is its
marked characteristic; Hormann, on the other hand, could only obtain it in the
form of a confused, radiated, glutinous mass, deposited when the solution had
reached a certain state of concentration. I found, however, that if 24°3 parts of
chinoline are added to 16°5 parts dry oxalic acid, dissolved in a small quantity of
water, the whole solidifies to a white crystalline mass, of the consistence of soft
cheese. The salt cannot be obtained pure by a random admixture of the ingre-
dients, as, although the chief tendency appears to be to form the binoxalate, yet
other compounds are also formed in sufficient quantity to prevent constant ana-
lytical results from being obtained, unless the above proportions are used. The
salt, before being employed for analysis, must be recrystallized from alcohol once
or twice, when it forms fine silky needles. It is partially decomposed by expo-
sure for two days to 212°, with evolution of chinoline, a salt being formed inter-
mediate in composition between the binoxalate and quadroxalate. It is necessary,
therefore, to dry it for analysis 2m vacuo over sulphuric acid.

6-995 grains of binoxalate of chinoline, dried in vacuo, gave
15,407 ... carbonic acid, and
2198. an, Water,
° Experiment. Calculation.
a_—_—=_—_—_——X—X__—_=_——.

Carbon, : : : . 60:07 60:27 Oss 132
Hydrogen, . z . . 4:44 4:11 HG 9
Nitrogen, . : : : at 6°39 N 14
Oxygen, 5 : ; : = 29°23 O, 64

|
q
d
f
‘

CHINOLINE AND ITS HOMOLOGUES. 387

Nitrate of Chinoline.—In some respects my experiments on this salt tally with
those of Dr Hormany, in others they differ considerably. It was obtained by the
last-named chemist by allowing a mixture of leukol and dilute nitric acid to rest
under a bell-jar; after some time the salt crystallized in confused concentric
needles, which were obtained white and dry by pressure between folds of filter-
ing paper. He does not appear to have analysed it. I found that if, after an excess
of nitric acid slightly diluted was added to chinoline, the fluid was evaporated on
the water-bath, a pasty mass was obtained, which solidified on cooling. From a
hot alcoholic solution fine white needles soon deposited, which were infusible at
212°, and unalterable in the air. Dr Hormann, on the contrary, found his salt
to fuse on moderate heating, and to rapidly become blood-red by exposure to the
air; these are, evidently, the characters of an impure substance. The nitrate of
chinoline was burnt with oxide of copper, a long column of copper turnings being
placed in the front of the tube.

6-590 grains of nitrate of chinoline, dried at 212°, gave
13516 ... carbonic acid, and
27530 ... water.
Experiment. Calculation.
Carbon, ; : ; 55°94 56°25 Cis 108
Hydrogen, . : ; 4:27 4:17 H, 8
Nitrogen, : ; aa 14:58 ING 28
Oxygen, : ; : ae 25:00 OF 48
100-00 192

Chinoline gives a very marked reaction with strong fuming nitric acid, and
which also shows its great stability. If a few drops of the base are allowed to
trickle down the side of a test-tube, and a small excess of the acid is added, the
two combine with violence, the portion of alkaloid adhering to the sides is con-
verted by the fumes of the acid into long needles, and, when cold, the whole fluid
solidifies to a beautifully white crystalline mass of pure nitrate. No nitrochino-
line, or any other decomposition product, is formed, if the base be free from im-
purities.

Bichromate of Chinoline.—GERuARDT, in describing this salt,* merely states,
that chromic acid in solution gives, with pure chinoline, an orange-yellow crys-
talline precipitate, and that the dry acid decomposes the base with inflammation,
Dr Hormany, in his paper on the coal bases, previously referred to, states that, a
short time after he had commenced the investigation of leukol, he was inclined
to consider it the same as that GERHARDT obtained by the action of hydrate of
potash on quinine, cinchonine, and strychnine. He says, however, that he soon
convinced himself that they were totally distinct, their behaviour towards a

* Traité de Chimie Organique, troisiéme partie, p. 150.

388 MR C. G. WILLIAMS’ RESEARCHES ON

solution of chromic acid being quite dissimilar, for while chinoline and its salts
gave a beautiful orange-yellow crystalline precipitate, leukol was oxidized and con-
verted into a black resinous oil. Subsequently,* Lizsie announced, upon the au-
thority of experiments made by Hormany, that perfectly pure leukol gave the
same crystalline precipitate with chromic acid. I have not been so successful as
M. Hormann; for, although the chinoline and lepidine procured by destructive
distillation from cinchonine have, in my hands, given salts of extreme beauty and
purity with chromic acid, I have failed to obtain the same result with either the
chinoline or lepidine from coal-tar. I have also boiled the bases from the latter
source with dilute chromic acid, to destroy impurities, and then separated them by
distillation with potash, but they merely gave an oily precipitate with chromic acid.
When dissolved in hydrochloric acid, and bichromate of potash is added, the same
result occurs. I even took a platinum salt of coal-lepidine, which yielded, on com-
bustion, the numbers detailed in Analysis I., p. 398; and, after having reobtained
the base by distillation with potash, endeavoured to procure from it a crystalline
chromate, but in vain, a red oil being the only product. It is true, that when I
added dilute chromic acid to chinoline from coal-tar, the sides of the tube acquired
a coating of very minute brilliant points, which reflected light with a peculiar
satin-like lustre; but the lens resolved them into oily globules. The following
experiments were, therefore, made upon chinoline from cinchonine. Neither Grr-
HARDT nor HormMaAnn have analysed the salt.

The beauty of the bichromate of lepidine described in my last paper,t induced
me to ascertain the composition and properties of the homologue next below it,
in the anticipation that its outward appearance would be equally striking. But
there are some slight differences in the two bodies; bichromate of chinoline is
still less soluble than the other salt, and this prevents the crystals from being
readily procured of so large a size. When dry, it is much more violently decom-
posed by heat than the lepidine compound. The fixed product is, however, the
same, namely, green oxide of chromium and carbonaceous matter. If the dry
salt be placed in a capsule, and heat be very gradually applied, no change at first
takes place, but suddenly it takes fire with explosive violence, and the greater
part of the green oxide and carbon is projected. I prepared the salt for analysis
by adding dilute chromic acid in excess to pure chinoline; at first the product is
somewhat resinous, but immediately it is touched with a glass rod, it becomes
gritty and crystalline. The solid is then filtered off, the mass slightly washed,
dissolved in boiling water, filtered to remove traces of an oily impurity, and, on
cooling, the fluid becomes filled with brilliant yellow needles arranged in groups.
It may be dried at 212° with safety, provided adhering moisture has been re-
moved as much as possible by pressure between folds of filtering paper. If the

* Chem. Gaz., vol. ui., p. 251 (1845). Proc. of Chem. Soc., April 7, 1845.
+ Trans. Roy. Soc. Edin., vol. xxi. part ii.

= &? das ade SD

CHINOLINE AND ITS HOMOLOGUES. 389

salt is previously moistened with hydrochloric acid, it may be ignited without

explosion, and the green oxide estimated with accuracy. The combustion was
made with oxide of copper.

carbonic acid, and

6:827 grains of bichromate of chinoline, dried at 212° gave
IE ops beie rs Bas
water.

Il 6-381 bichromate of chinoline, dried at 212°, gave, on ignition,
f 2°072 green oxide of chromium,
Ill 5°534 bichromate of chinoline, dried at 212°, gave, on ignition,
Weer fshre green oxide of chromium.
Experiment. Calculation.
waa oa gre aE Te ae
I. II. III
Carbon, 45:08 ok 45-11 Ge 108
Hydrogen, 3°49 3°34 H, 8
Nitrogen, sas Lists 5°85 N 14
Chromium, 22:40 22:28 22:31 Cr, 53°4
Oxygen, : 23°39 Oo; 56:0
100-00 239°4

Density of the Vapour of Chinoline.—In Dr Hormann’s paper on the coal bases,
he states that a determination of the density of the vapour of leukol (chinoline)
failed, owing to its leaving a yellow residue on distillation. I have not found this
circumstance to operate sufficiently in the case of chinoline from cinchonine, to
cause more error than is usually found in determining the vapour densities of
bodies obtained by fractional distillation, and having so high a boiling point. The
specimen used, boiled in the fourteenth rectification between 460° and 470° F.

| The formula

requires

Temperature of air,
vapour, .

13° centigrade.
Dinners
751 millimetres.
330 cent. cub.

cam ae.
0:4980 grammes.

Pressure, :

Capacity of balloon,
Residual air,

Excess of weight of balloon,

C,, H, N
18 volumes carbon vapour, 0-829 . 18=14°922
14 hydrogen, 0:0692 .14= :9688
2 nitrogen, 0:9713. 2= 1:9426
17°8334
4
Experiment. Theory.
C,, H, N = 4 volumes.
4:5190 4:4583

Action of Iodide of Methyl on Chinoline.

= 4:4583

Hydriodate of Methyl-Chinoline—When an excess of iodide of methyl is

added to chinoline, and the mixture, inclosed in a pressure tube, is heated for
VOL. XXI. PART III.

DN

390 MR C. G. WILLIAMS’ RESEARCHES ON

ten minutes to 212°, combination is perfectly effected, a finely crystallized hy-
driodate resulting. If this salt, which is perhaps more correctly called iodide of
methyl-chinoline-ammonium, is treated in the cold with excess of oxide of silver,
a strongly alkaline solution is obtained, containing the hydrated oxide of the am-
monium base. The solution possesses little stability; on heating with potash,
an excessively pungent odour is evolved, acting strongly on the eyes and mucous
membrane of the nose. The solution reddens turmeric paper as powerfully as
solution of caustic potash, and instantly restores the colour of reddened litmus.
The reactions of this base, generally, are the same as those of the ethyl compound
next to be described. The smell of a volatile base, a product of the decomposi-
tion of methyl-chinoline, is evolved from the moment of its formation; it appears
to be methylamine.

By alternate precipitation of the hydriodate by nitrate of silver, hydrochloric
acid, and bichloride of platinum, after removal of the chloride of silver, a sparingly
soluble platinum salt was obtained. The following is the result of its ana-
lysis :—

carbonic aeid, and

water.

8-930 Bee of platinochloride of methyl-chinoline, gave
I. < 11:350
2°496

platinochloride of methyl-chinoline gave
carbonic acid, and

8515
Bi a a rg
2°303 water.
7861 platinochloride of methyl-chinoline gave
2217 platinum,
5165 platinochloride of methyl-chinoline gave
1:456 platinum.
Experiment. Mean. Calculation.
—_——— OO —
le Il. Ill. Iy.
Carbon, 34:66 34:52 34°59 34°33 CS 120
Hydrogen, 3:11 3°00 3:06 2°86 He 10
Nitrogen, ; ae ee 4:01 N 14
Chlorine, oes wee ose 30°47 Cl, 106°5
Platinum, 28:20 28°19 28°20 28°33 Pt 99
100-00 349°5

Methyl-chinoline is, therefore, isomeric with lepidine, but has no other point
of resemblance. The decompositions of the hydriodate almost exactly resemble
those of the ethyl base, and, as the atomic weight of the latter, being higher, gave
it an advantage for experiment, I selected it for the purpose.

Action of Iodide of Ethyl on Chinoline.

Hydriodate of Ethyl-Chinoline.—No action takes place on the mere addition _
of excess of iodide of ethyl to chinoline, but if the tube containing the mixture be _
sealed and exposed for some hours to a temperature of 212°, the whole becomes a

CHINOLINE AND ITS HOMOLOGUES. 391

mass of crystals. When this is the case, and the tube cools, the end may be cut
off, a tube bent twice at right angles attached by means ofa cork, and, the pressure-
tube being immersed in the water-bath, the excess of iodide of ethyl distilled
over. The crystals are then dissolved out in a small quantity of hot alcohol, and
the solution allowed to cool. ‘The first crop is of a rich yellow colour, becoming
of a pale lemon tint on recrystallization. In the state in which the salt is thus
obtained it possesses the property of becoming a deep blood-red at 212°, and regain-
ing its normal tint on cooling; this peculiarity becomes much lessened by a re-
petition of the process. The crystals appear to be cubic, and are easily obtained
of considerable size. They dissolve more readily in water than alcohol, but the
latter is the best solvent for the purposes of crystallization.

6:336 grains of hydriodate of ethyl-chinoline, dried at 212°, gave
I. < 10-810 carbonic acid, and
2513 .., Water.
II 6°684 ... hydriodate of ethyl-chinoline, dried at 212°, gave
: 5-457 iodide of silver.
Experiment, Calculation.
——— ee
MI 1G
Carbon, 46°53 46°32 oe 132
Hydrogen, 4:4] 4:21 is OF 12
Nitrogen, ee Bho 4-91 N 14
Todine 44°12 44°56 T 127
100:00 285

Platinum Salt of Ethyl-Chinoline.—After adding nitrate of silver to a solution
of hydriodate of ethyl-chinoline, as in making the iodine determination last men-
tioned, the excess of silver was removed by the addition of hydrochloric acid, the
liquid filtered, and evaporated to a moderate bulk, on the addition of bichloride of
platinum, a rich golden-yellow precipitate of sparing solubility was obtained; it
was first washed with a little water, and afterwards with alcohol.

6°813 grains of platinochloride of ethyl-chinoline gave
1847 ...' platinum.

Agreeing with the formula
C,, H,, N, H Cl + Pt Cl,.

Experiment. Calculation.

roo
Carbon, . 4 ; ae 36°31 Cy. 132
Hydrogen, ; ; sie 3°30 H,, 12
Nitrogen, . : : ies 3°85 N 14
Chlorine, . . 4 dis 29°30 Cl, 106°5
Platinum, . ’ ottes feud 27°24 Pt 99

100-00 363°5

392 MR C. G. WILLIAMS’ RESEARCHES ON

It is evident that ethyl-chinoline is isomeric with cryptidine, the new base
to be described further on.

Action of Oxide of Silver on Iodide of Ethyl-Chinoline.

Hydrated Oxide of Ethyl-Chinoline-Ammonium.— solution of iodide of ethyl-
chinoline is decomposed with ease by oxide of silver, even in the cold, a colourless
strongly alkaline fluid being formed, containing the fixed base corresponding to
the hydrated oxide of tetrethylammonium. The solution instantly reddens tur-
meric paper, and restores the colour of reddened litmus. It precipitates solutions
of sulphate of copper, sesquichloride of iron, acetate of lead, and corrosive subli-
mate. The addition of a small quantity to ared solution of bichromate of potash
renders it yellow, by neutralizing the second equivalent of chromic acid. The
solution of the base decomposes chloride of ammonium, liberating the ammonia
freely.

The heat of a water-bath decomposes the solution of the hydrated oxide, with
production of a splendid crimson colour, the sides of the basin where the liquid
has dried becoming a brilliant emerald green, passing in a few seconds to a blue
of great beauty and intensity. These colours, like those to be mentioned pre-
sently, evidently depend upon oxidation, and would require a very large amount
of material to follow out in detail. When the solution of hydriodate of ethyl-
chinoline is heated on the water-bath with excess of oxide of silver, a volatile
product is evolved, acting strongly upon the eyes.

Action of Sulphate of Silver upon Hydriodate of Ethyl-Chinoline.

If hot solutions of sulphate of silver and hydriodate of ethyl-chinoline are
mixed, double decomposition ensues, without any further action taking place, the
solution of sulphate of ethyl-chinoline remaining colourless, and the iodide of
silver separated being of the normal tint; but, if it be attempted to concentrate
the solution by evaporation on the water bath, it undergoes a curious metamor-
phosis, the sides of the dish, where the solution has dried, become a deep pure
blue, but, as the evaporation proceeds, the solution becomes crimson, and when
dry, the mass is so deep.in tint, as to be nearly black. The dry substance has a
slight coppery lustre, like that which indigo possesses when rubbed. It dissolves
in water, the solution being of the most gorgeous crimson, becoming rose-coloured
by addition of ammonia, while hydrochloric or nitric acids convert it to a scarlet.
The colour is tolerably stable, requiring a considerable excess of bromine water
to decompose it, the fluid then becoming reddish-brown.

The crimson liquid undoubtedly contains the sulphate of a new base, apparently
a product of oxidation of ethyl-chinoline. The reactions upon which this suppo-
sition is founded, are the following :—If solution of potash be added to the crim-
son solution, the colouring matter is almost entirely precipitated, and, ifthe experi-

Se

==>

a?
ro"

ae

‘

f

CHINOLINE AND ITS HOMOLOGUES. 393

ment be successful, the solution merely retains a slight blue tinge. This preci-
pitate appears to be the new base, although probably in a very impure state.
When first thrown down, it has a beautiful reddish-violet colour, like that of the
crystallized sesquichloride of chromium. It may be washed with water on a
filter, being sparingly soluble; it dissolves readily in alcohol, forming a fine crim-
son fluid, which precipitates a spirituous solution of chloride of mercury. The
base dissolves readily in hydrochloric acid, the solution giving a voluminous pre-
cipitate with bichloride of platinum. The platinum salt, after well washing with
water, was burnt for the percentage of metal, to ascertain whether its atomic
weight was higher or lower than that of ethyl-chinoline.
{ 2°081 grains of platinum salt gave

492 ... platinum.
212:2 157:0
Atomic weight of new base. Atomic weight of ethyl-chinoline.

The atomic weight which is derived from this experiment is so excessively
high, that no simple relation is apparent between the red product and ethyl-
chinoline. The single platinum determination, although carefully made, is evi-
dently insufficient to enable any speculation to be made as to the nature of the
decomposition.

It is known that most nitryl bases (those composed solely of the alcohol
radicals being the chief exceptions) yield colours by the action of oxide of silver
on the ammonium compounds formed with methyl, ethyl, and amyl, but I think
none yet worked on yield such magnificent tints as those mentioned in this paper.
The subject has another and much greater point of interest than the mere forma-
tion of coloured reactions, however beautiful they may be, inasmuch as the care-
ful following out of the decompositions on the large scale promises to assist us in
acquiring a knowledge of the constitution of alkaloids of this class. I have there-
fore promised myself to examine the matter more fully, when the other investi-
gations with which I am now occupied are concluded.

Action of Iodide of Amyl on Chinoline.

Hydriodate of Amyl-Chinoline.—lodide of amy] reacts with comparative slow-
ness upon chinoline. It is necessary to keep the materials in a pressure-tube for
some hours at 212° to effect combination. The iodide crystallizes from alcohol with
extreme readiness, and when evaporated slowly upon flat surfaces presents under
the lens very peculiar and beautiful forms. On one occasion, after dissolving the
iodide in alcohol in a beaker, the fluid was poured into another vessel, and the
solution remaining on the sides crystallized in the manner I have endeavoured to
illustrate in the annexed sketch. The figure represents the forms about four
times the natural size.

VOL. XXI. PART III. 5 0

394 MR C. G. WILLIAMS’ RESEARCHES ON

The hydriodate of amyl chinoline gave, in a
determination of the percentage of iodine, the fol-
lowing numbers.

{ 9-882 grains hydriodate amyl-chinoline gave

7:086 ... iodide silver.
Experiment. Calculation.
ee

\, 74 Carbon, : ; a 51:38 Ce 168

} i Hydrogen, . ; a: 5+50 UB 18

A Nitrogen, . a ait 4:28 N 14

I MY. ~(/\ Iodine, SS ra 38:84 I 127
My AN yy WP \ SS

GZ \ i (x ‘S \ e A

LN 4 WT A \ 100-00 327

Bi) |

The fluid from which the iodine had been preci-
pitated was treated with hydrochloric acid in excess,
the chloride of silver removed by filtration, and the
fluid evaporated to a moderate bulk, excess of bi-
chloride of platinum was then added, and the pre-
cipitated platinum salt washed, first with a little
water, and then with a mixture of alcohol and ether. The platinochloride of amyl-
chinoline is only sparingly soluble in water, it was dried at 212°, and burnt with
chromate of lead and copper turnings.

6-756 grains of platino-chloride of amyl-chinoline, gave

10:233 ... carbonic acid, and
2°813..°.... water
77150 ~~... platinochloride of amyl-chinoline gave
1-733 =... platinum.
Experiment. Calculation.
Aa oe ee
Carbon, 41:31 41:43 ie 168
Hydrogen, . ; 4:63 4:44 H,, 18
Nitrogen, . : he 3°45 N 14
Chlorine, . ‘ im 26:26 Cl, 106°5
Platnum, . ‘ 24:24 24-42 Pt 99
100-00 405°5

Action of Chlorine on Chinoline.—According to GERHARDT,* chlorine converts
chinoline into a black resin, but my experiments show that it acts in a very dif-
ferent manner, if care be taken to prevent rise of temperature. On dropping
chinoline into a large glass vessel of the gas, and leaving it for twelve or fourteen
hours, a yellow oil is produced, which, on treatment with water, leaves a white

insoluble matter, which I have not yet had an opportunity of studying more in
detail.

Action of Chloride of Acetyl on Chinoline.—Chloride of acetyl on being added

* Traité, troisiéme partie, p. 150.

CHINOLINE AND ITS HOMOLOGUES. 395

to chinoline, develops much heat, and on evaporation at 212°, a crystalline mass
was obtained, but so deliquescent, as to be unfit for examination.

On the Chinoline Series as it occurs in OCoal-Tar.

In my paper “ On some of the Basic Constituents of Coal-Naphtha and on
_Chryséne,” I ventured to express a belief, that chinoline was not the only mem-
ber of the group to which it belongs present in coal-tar; and feeling assured that
other homologues remained to be discovered, I was desirous of testing the accuracy
of the supposition. Owing to the kindness of Mr Grorcre Mitter of Dalmarnock,
I was enabled to obtain fifty gallons of coal-oil of a very. high boiling point, and
of a density greater than that of water. It was shaken with sulphuric acid to
extract the alkaloids, and the acid fluid after dilution with water was treated with
excess of lime, and distilled as long as any came over. As the amount of bases of
the Dippel series present, was not large, the product being of such a high boiling
point, I did not add potash to separate the more soluble portion, but only collected
that part which, from its density and insolubility, sank to the bottom of the fluid
accompanying it in the distillation. By means of a tap funnel, the basic-oil was
separated from the chief part of the water accompanying it, which contained some
of the pyridine series in solution. The bases thus obtained are exceedingly im-
pure, and contain aniline and some non-basic substances. It being probable,
_ that toluidine and even other members of the same series might be present, I
thought that as apparently insurmountable difficulties prevented their separation
from the chinoline series by means of oxalic acid, or similar methods, their
presence might nevertheless be made manifest through their products of decom-
position. With this view, I treated the mixed bases with nitrite of potash and
hydrochloric acid, in the manner indicated by Hunt,* and by this means effec-
tually decomposed all traces of the aniline group present. But the amount of
oil heavier than water containing the hydrates of phenyl and cresyl was too small
to allow of my further examining them. I propose, however, to return to the
subject at a future time.

The acid fluid, after decantation from the heavy oil last alluded to, was then
placed in a retort, and a jet of steam sent through the tubulature to the bottom
of the liquid; by this means, many non-basic impurities were removed, and
amongst them a white crystalline solid distilled over with the steam, and which
eventually proved to be naphthaline. The acid fluid in the retort, after being
filtered through pulverized charcoal, to separate resinous matters not volatilized,
was treated with potash, to liberate the base, which was then separated by a tap
funnel, and completely dried by digestion with sticks of potash. It is proper to

* Sizrzman’s Journal 1849; Chem. Gaz., Jan. 1850; Geruarpt, Traité, tome 3™, p. 83;
Hormann, Quart. Jour. Chem. Soc.

396 MR C. G. WILLIAMS’ RESEARCHES ON

mention, that by this treatment, the boiling point of the bases was considerably
raised, the aniline being removed, which boils 100° below chinoline.

The bases, as purified by the above method yield, on distillation, fractions
from 350° to 525°, Considerably more than one hundred distillations were
made before sufficient separation had taken place, to justify me in making any
analyses.

Chinoline having already been proved to exist in coal-tar, I began the experi-
ments by searching for lepidine. This base, which was discovered by me* among
the volatile alkaloids procured by distilling cinchonine with potash, has the
formula,

C,H, WN,
which was established by analyses of the platinum salt, nitrate, hydrochlorate,
and bichromate, confirmed also by a determination of its vapour density.

As obtained from coal-tar, lepidine is in the form of an oil, having an odour
almost exactly the same as that from cinchonine. But it is impossible by distil-
lation alone, even after the treatment of the crude base with nitrous acid, to
procure it in the same state as from the source where it was first found. Coal-
lepidine, therefore, yields salts which, for the most part, crystallize with in-
comparably greater difficulty than that from cinchonine. When dissolved in an
acid, although the solution is perfect, there is always an after-odour evolved,
somewhat like naphthaline, unless the base has been purified with great care.
I was unable, by any means at at my disposal, to obtain the bichromate in a crys-
talline state, whereas the lepidine from cinchonine yields a beautiful salt, in
brilliant yellow needles half-an-inch long. Even when coal-lepidine is boiled with
diluted chromic acid for an hour, the base, when separated and redistilled, gives
an oily precipitate with chromic acid; moreover, the same occurs if the base be
dissolved in hydrochloric acid, and a solution of bichromate of potash is added,
as has been previously mentioned in describing the bichromate of chinoline. The
red oi] obtained in this manner from coal-lepidine may be kept for weeks without
showing any tendency either to crystallize or decompose; even the base obtained
from a platinum salt of considerable purity, behaved in the same way. On the
other hand, coal-lepidine reacts with nitric acid and some other re-agents, like
that from cinchonine.

If it were not for the decisive manner in which the fact of Dr Hormann’s having
obtained the crystalline precipitate with leukol and chromic acid has been an-
nounced, I should have felt justified in asserting that the bases derived from the
two sources were isomeric but not identical; but as the last-named chemist’s well-
known accuracy prevents me from entertaining a belief in the possibility of an error
of experiment, I can only express my regret, that I am ignorant of the method of

* Trans. Royal Soc. Edin., vol. xxi., pt. 27.

0 PO ii i ii

eng \

ol
—
»
¢
i

CHINOLINE AND ITS HOMOLOGUES. 397

purification adopted by him. The most satisfactory mode of explanation of the
differences in the properties of the coal and cinchonine series, as obtained by me, is
that they are in a peculiar molecular condition, analogous in some respects to the
phenomena known in the cases of quinine, the amylic alcohol, and many other
bodies, instances of which are daily becoming more numerous. Chemists are aware
that even variations in the density and boiling point of the same fluid, when in dif-
ferent states, have been observed; and I may mention, as corroborative of this,
that with bases distilled the same number of times, lepidine as pure as I could
procure it from both sources differed in boiling point by 25° F.; for the lowest frac-
tion of coal-lepidine that gave correct results on analysis distilled between 485°
and 495°, whereas the lowest fraction of the same base from cinchonine, boiled be-
tween 510° and 520° F. Another fact which seems corroborative of the supposi-
tion that Dr Hormann obtained the chinoline from coal-tar in the state in which
I procured it from cinchonine, is found in the circumstance that the density of
chinoline from coal-tar was ascertained by him to be 1-081, or very near the same
number as in my determination of the density of the same base from cinchonine,
viz., 1085. But the coal bases examined by me were lighter than this; for even
the lepidine from the the last source had a density of only 1:072 at 60° F., being
actually lighter than the homologue, one step below from cinchonine.

I have observed with the pyridine series, as obtained from bone-oil, coal-
naphtha, and bituminous shale, that considerable differences are found in their
power of forming crystalline salts, and it is, therefore, most probable that the
same distinctions exist between them that are met with in the case of the bases
from coal and cinchonine. [I trust eventually to be able to elucidate some of
these points, by subjecting chinoline from both the above substances to the action
of polarized light.

The lepidine platinum salt, from cinchonine, precipitates at once in a pulveru-
lent state; but from coal it is for a few seconds soft and resinous, but soon be-
comes hard_and crystalline. The following are my analyses of it from the latter
source :—

( 9-216 grains crystallized platinochloride of lepidine from fraction boiling 485°-95°
14th rectification, dried at 212°, gave

i. } 11:652 ... carbonic acid, and
| 2°466 ... water.
5:954 ... platinochloride lepidine from fraction 485°-95°, gave
ET. :
1673 .. platinum.
8-754 ... platinochloride lepidine from fraction 495°-505°, 14th rectification, gave
III.<11:101 ... carbonic acid, and
2°452 ... water.
5554 ... platinochloride lepidine, same as last, gave
IV. ;
1575... platinum.
yf 5047 ... platinum salt, 485°-95° crystallized, gave
“{ 1:417 ~~... platinum.

VOL. XXI. PART III. 5P

398 MR C. G. WILLIAMS’ RESEARCHES ON

Experiment. Mean. Calculation.
OO _—_— —_——————
is II. III. LV. Vv.

Carbon, 34°48 an 34:58 ste baa 34°53 34°33 C,, 120

Hydrogen, 2°97 Kat 311 ee sa 3°04 286 HH, 710

Nitrogen, ao oe sa Sais aie on 4:01 N 14
Chlorine, oe ome “ig a at “e. 30°47 Cl, 106-5

Platinum ane, 28-09 see 28°36 28:08 28°17 28°33 Pt 99
100-00 349°5

In the following table, the mean of these results is compared with my ana-
lyses of the platinum salt from the cinchonine bases.

Coal-Tar. Cinchonine.

Mean. Mean. Theory.
Carbon, : F . 34:53 34:04 34°33
Hydrogen, . : . 3804 2:95 2°86
Nitrogen, . : JERE. pee 4:01
Chlorine, . A : bot can 30:47
Platinum, . : ap DOLE 28:13 28°33

Action of Iodide of Ethyl on Lepidine.

Hydriodate of Ethyl-Lepidine.—As it was evident that the process for prepar-
ing this compound, and from it the platinum salt, was one of purification, I thought
that I should, by this means, obtain nearer results on analysis than was the case
with the experiments last quoted; and the following may be considered as con-
firming the truth of the supposition.

Coal-lepidine, sealed in a tube with excess of iodide of ethyl, and exposed for
some hours to 212°, yields a mass of brown needles, which, on recrystallization
from alcohol, are of a brilliant canary yellow. They have the same property of
becoming red at 212° as the corresponding salt of chinoline, although scarcely to

the same degree.
{ 7-111 grains iodide ethyl-lepidine gave

5:°595 ... iodide silver.
or per cent.—
Experiment. Calculation.
So
Carbon, : : See 48°16 Garten ion:
Hydrogen, . : 5o8 4:68 Ey ee
Nitrogen, . 5 sip 4:68 N 14
Todine, : 3 42°52 42:48 I 127
100:00 299

Platinum Salt of Ethyl-Lepidine.—This salt was obtained in the same manner
as the corresponding one of ethyl-chinoline. It is, at the first moment of preci-
pitation, somewhat soft, but soon becomes hard and crystallized. It was pul-

verized and well washed with a mixture of alcohol and ether previous to ama-

lysis.

CHINOLINE AND ITS HOMOLOGUES.

8-374 ar platinochloride ethyl-lepidine gave

399

I. ¢ 11:667 carbonic acid, and
2°880 water. |
II 6377 platinochloride ethyl-lepidine gave
“| 1688 platinum.
It 4952 platinochloride ethyl-lepidine gave
: { 1317 platinum.
Experiment. Calculation.

III.

Carbon, 38-00 38:14. G,, , 144
Hydrogen, 3°82 ok 1S ee
Nitrogen, 3°71 N 14
Chlorine, mo ety 28°21 Cl, 106°5
Platinum, 26°47 26°60 26°23 Pt 99
100-00 377°5

Density of Vapour of Lepidine.—In my former paper on the chinoline bases,
I gave 5:14 as the density of the vapour of lepidine, as found by experiment, and
I was desirous of ascertaining that of the same base, as extracted from coal-tar,
in order to serve as a comparison. It is remarkable to observe the difference
which an increment of C, H, has in modifying the power of substances to resist the
decomposing influence of heat. While, in taking the density of chinoline at 531° F.,
being 71° above its boiling point, the fluid condensed in the balloon was almost
colourless, lepidine after exposure under the same circumstances to only 523° F.,
or 28° above its boiling point, had become nearly black; this darkening, caused
by separation of carbon, prevented me from making the experiment at a tempera-
ture as much above the boiling point as in the case of chinoline, and the two
sources of error have the effect of making the density come out somewhat too high.

Temperature of air,
vapour,

15° centigrade.
3. sue
755 millimetres.
331 cent. cub.
6745 grammes.
6 cent. cub.
5:15

Pressure,
Capacity of balloon 5
Excess of weight of on
Residual air,
Density,
The formula

requires the following numbers :—

20 volumes carbon vapour, =0°8290 . 20=16:580

18 hydrogen, =0:0692 .18= 1:2456
2 ... nitrogen, =0:97138 . 2=-1-9426
19°7682
=4:94205
4
Density of vapour of lepidine Density of vapour of lepidine Theory.

from cinchonine.

5:14

from coal.

C,, H, N=4 volumes.
5°15

4:94

400 MR C. G. WILLIAMS’ RESEARCHES ON

On Cryptidine, a new Volatile Alkaloid homologous with Chinoline.

In examining the highest fractions of the bases from coal-tar, I have ascer-
tained the presence of a new volatile base, to which I have given the above
name.* The quantity at my disposal was so exceedingly small, that the plati-
num salt is the only compound I have been able to obtain in a state of tolerable
purity; but the analyses of this substance leave no doubt whatever of the con-
stitution of this the third homologue of the chinoline series.

If a solution of bichloride of platinum be added to a solution in hydrochloric
acid of the fraction boiling about 525°, a pasty yellow mass precipitates, and,
on stirring, adheres to the rod. In a few seconds the precipitate becomes crys-
talline, and is no longer adhesive, and, if it is now dissolved in boiling water,
it separates on cooling in groups of yellow needles, sparingly soluble in cold
water. Two specimens of salt prepared in this manner, and well washed, first
with water, and after with a mixture of alcohol and ether, yielded on combus-
tion the numbers following :— .

8-018 grains platinochloride eryptidine, dried at 212°, gave
TI. < 10°535 carbonic acid, and
2.493 ... water.
6-066 ... platinochloride of cryptidine, gave
1645 ... platinum.
8958 ... platinochloride of cryptidine (another preparation), gave
ITI. < 11:807 ... carbonic acid, and
2647 ... water.
Iv 5:990 ... platinochloride of eryptidime, gave
*| 1631 .... platinum.
Experiment. Mean. Calculation.
SSS
WIG II. Ii. IV.
Carbon, . . . 35°83 . 35°95 a 35°89 36°31 C,, 132
Hydrogen, . . 3°45 = 3°28 Bes 3°37 330. Hoya
Nitrogen,” “<0. eae we ore nos se 385 N 14
Chlorine, Re ak 5 ee a +4 29°30 Cl, 106°5
Platinum, <= .. 27°12 at BF25 =| BF-18 97:24 Pt 390
100-00 363°5

If the fraction boiling at 515°-25° is treated with ordinary nitric acid, it dis-
solves with a purple coloration, and, if the solution is evaporated to dryness,
and redissolved in water, an insoluble yellow powder becomes apparent. To the
filtered solution bichloride of platinum being added, an adhesive precipitate
is formed, having the properties previously assigned to the platinochloride of
cryptidine, as obtained from coal-tar. On solution in boiling water and subsequent
cooling, a fine crop of orange-yellow needles was obtained, which, on combustion
with chromate of lead and copper turnings, gave the result annexed.

* From xgurros.

CHINOLINE AND ITS HOMOLOGUES. | 401

7°921 grains platinochloride of cryptidine, after treatment with nitric

I acid, &c., dried at 212°, gave
*) 10-603... carbonic acid, and
2°453 +... water.
ll { wane aes ere of cryptidine, same as last, gave
; . ... platinum.
I. & I. Calculation,

Carbon, ; 5 36°51 36°31
Hydrogen, . : 3°44 3°30
Nitrogen, : . a 3°85
Chlorine, , : ie 29°30
Platnum, . 3 27°25 27°24

100-00
A very perceptible increase in the carbon is, therefore, obtained by the remo-
val of the impurity rendered insoluble by means of nitric acid.

Chinoline is, therefore, the first of a series of homologous nitryl bases, of
which three members are now known, viz. :—

Chinoline, s : CN:

Lepidine, ? Cols, IN

Cryptidine, ‘ Cee N
And of which a greater number might possibly be obtained by an extension of

the inquiry.

VOL. XXI. PART III. 5Q

a

( 403 )

XXVII. On Fermat’s Theorem. By H. F. Tarzot, Esq., F.R.S., &c.
(Read 7th April 1856.)

It is well known that no satisfactory demonstration has ever been given of
Fermat’s celebrated theorem, which asserts that the equation a"=b" +c" is impos-
sible, if a, b, c, are whole numbers, and 7 is any whole number greater than 2.
In LEGENDRE’s Théorie des Nombres, he demonstrates the cases of n=3, n=4, and
n=5, the latter only in his Second Supplement. In CRELLE’s Mathematical Jour-
nal, ix. 390, M. DiricHLetT, a mathematician of Berlin, has demonstrated the case
of n—14, but I am not aware whether his demonstration is considered successful.
LEGENDRE informs us (Second Supplement, p. 3) that the Academy of Sciences,
with the view of doing honour to the memory of FEeRMat, proposed, as the sub-
ject of one of its mathematical prizes, the demonstration of this theorem; but
the Concourse, though prolonged beyond the usual term, produced no result.

It is a remarkable circumstance, however, that FErmat himself was in pos-
session of the demonstration, or at least believed himself to be so, and he describes
his demonstration as being a wonderful one—mirabilem sane.* He does not say that
the theorem itself is wonderful, but his demonstration of it; from which I think
it likely that he meant to say that it was very remarkable for its shortness and
simplicity.

Since, however, subsequent mathematicians have failed to discover any de-
monstration, much less an extremely simple one, of this celebrated theorem, it
has been surmised that Fermat deceived himself in this matter, and that his
demonstration, if it had been preserved to us, would have proved unsatisfactory.
LEGENDRE says, “‘FERMAT a pu se méprendre sur l’exactitude ou la généralite de
sa démonstration.”

Nevertheless, in considering this question attentively, I have found that there
is one case in which Fermat’s theorem admits of a singularly simple demonstra-
tion; and as [ do not find it noticed in any mathematical work to which I have
been able to refer, I think it worthy of being brought under the notice of mathe-
maticians. It may possibly prove to be a step in the right direction towards the
recovery of Frrmat’s lost demonstration. It is, moreover, in itself a very ex-
tended and remarkable theorem, although less so than that of FERMaT.

* « Cubum autem in duos cubos aut quadrato-quadratum in duos quadrato-quadratos et gene-
raliter nullam in infinitum, ultra quadratum, potestatem in duos ejusdem nominis fas est dividere.
Cujus rei demonstrationem mirabilem sané detexi. Hanc marginis exiguitas non caperet.”—Frrmar,
Notes sur Diophante, p. 61.

VOL. XXI. PART III. 5R

404 H. F. TALBOT ON FERMAT’S THEOREM.

The case which admits of this simple demonstration, is that in which one of
the three numbers a, b, c, is a prime number; and it divides itself into the two
following theorems :—

Let a be any prime number, then,

Theorem I. If n is any odd number greater than 1, the equation a*=s"+c" is
impossible.

Theorem Il. If m is any number, odd or even, greater than 1, the equation
a*=b"—c" is impossible.

But Theorem II. admits a case of exception, viz., that whenever }—c=1, the
theorem remains undemonstrated. When n=2, this case of exception actually
occurs, because a?=b?—c? is possible, although a be a prime number. For ex-
ample, when a=3, 3?=5?—4?.

Such a case of exception, however, does not occur when n=3, or n=4, Or,
n=5, aS LEGENDRE has demonstrated. But that is no reason why it should not
occur with other values of ». And therefore it appears that the generality of
FerMAT’s theorem is assailable in this direction ; a fact which deserves the atten-
tion of mathematicians, especially as FeErMat himself does not appear to have
adverted to it.

In order to demonstrate these propositions, I will recall to mind some of the
leading principles of the Theory of Numbers.

1. Ifa prime number does not divide either of the whole numbers A or B, it
does not divide their product AB. LEGENDRE, p. 3, gives a very rigorous demon-
stration of this important theorem.

2. When a number has been divided into its prime factors, it cannot be
divided into other prime factors different from the first ones.

3. The product of any number of primes, cannot be equal to the product of
any number of other primes different from the first ones.

And here it may be observed, that although these products cannot be equal,
nothing prevents them from approximating as closely as possible to equality,
i.é., differing by a single unit. For example, the product of the

three primes 7 x 17 x 83 = 9877
that of 2x 11 x 449 = 9878
that of 3x 37 x 89 = 9879.
These things being premised, we may proceed as follows :—

Demonstration of Theorem I.

Let us suppose, if possible, a*=b"+c¢". Then because m is an odd number,
b"+c” is divisible by +c. Let the quotient be Q. Therefore a"=d+c.Q. Now

since @ is prime, the first side of the equation is the product of the m factors —

axaxax &c. Consequently the second side of the equation is the product of

H. F. TALBOT ON FERMAT’S THEOREM. 405

the same 7 factors. And it cannot possibly have any other. Therefore, since it
has the factor 6+¢, this factor must itself be either = a, or divisible by a.

But we shall now proceed to show that 5+¢ cannot possibly be divisible by a,
and therefore the original hypothesis, viz., that v'=b"+c", must be impossible.

In order to show this, we will first observe that (6+c)" is greater than 6"+c’,

since it exceeds it by the quantity nb" + — br? 2 4. &e.

But b"+c"=a" by hypothesis.
b+e > a”, and bc >a.
On the other hand, since evidently

ba and c< a b+e< 2a.

But since 5+ is greater than a and less than 2 a, it cannot possibly be divisible by
a. Which wastobe shown. And it therefore follows that the equation a" =b" +c" is
impossible, if 2 is an odd number > 1, always supposing, however, that a is a
prime number.

Demonstration of Theorem II.

Let us suppose, if possible, that a*=b"—c". Then since t"—c’ is always divi-
sible by b—c, let the quotient be Q. Therefore a*=b—c.Q. Now since a is a
prime number, the first side of this equation is the product of the n factors
axaxax &e.

Consequently the second side of the equation is the product of the same n fac-
tors, and it cannot possibly have any other. Therefore, since it has the factor
b—c, this factor must itself be either = @ or divisible by a. But, on the other
hand, it can be shown, as follows, that it is not divisible by a.

Since a"=b"—c", therefore b"=a" +c", and bis the greatest of the three numbers.
Now since a+ ¢|" DYarte’, and a®+o"=bY, «. ate’ OS bY, and a+e » b, anda > b—e.

Since, therefore a is greater than b—c, it cannot possibly divide it. And there-
fore the original hypothesis that a*=b'—c’ is impossible, if m is any number
x 1, always, however, on the supposition that @ is prime.

But in reviewing this demonstration, we find a case of exception; for it will
be seen that we assert that b—¢ can have no factor different from @. This is cor-
rect in one sense, but not so in another, since it may have the factor wnity, which
is usually disregarded, though it is here a consideration of the greatest import-
ance. And since we have shown that 6—c¢ cannot have either the factor a@ or any
other factor, it follows that it can have no factor except wnity, that is to say, it
must be itself equal to unity, and can have no other value.

The above two theorems form together a conclusive demonstration of Frr-
MAt’s theorem, in the case of a prime number.

406 H, F. TALBOT ON FERMAT’S THEOREM.

Extension of FERMAT’S Theorem.

Always supposing that @ is a prime number, and that b—c is greater than
unity, the theorem a"=b"—c" (impossible), may be extended to a much more ge-
neral theorem, viz., that a*=b"—c" is impossible, provided that m is less than .

Demonstration. Let a=k", where we no longer suppose & to be an integer.
Therefore since m <n, a must be greater than s. But k"=b"—c" by hypothesis;
therefore b"=c'+k", which is less than c+£|"; therefore 0 is less than c+%, and
b—cislessthan &. A fortiori, b—c is less than a.

But in the given equation a*=b"—c", since @ is prime, and b—c divides b"—c’,
therefore }—c=a, or else is divisible by a@, a number which we have shown to be
greater than itself, which is impossible. Therefore a*=b"—c" is impossible un-
less m iS n. But if m > n, it is possible.

Example. 3°=6 — 3°, where a is prime and b—c greater than 1, but m > 2.

By an analogous method we obtain the extended theorem No. II.

If m is an odd number, a”=b"+c" is impossible, provided that a is prime, and

We have hitherto supposed @ to be prime, whereas FerMaAt’s theorem has no
such limitation; it remains, therefore, to enquire how far the present extended
theorems are true when @ is not a prime number.

In conclusion, we may oberve that the ancients themselves had discovered the
possibility of the equation a?=b? +c’.

But from what precedes, we may deduce the following theorems concerning it.

1. If a? =0?+c¢?, and c is a prime number, then a—d is always =1.

2. If a?=b? +c, b and ¢ cannot both be prime numbers. For because c is prime,
it follows that b=a—1.

And because 0 is prime, therefore c=a—1, therefore b=c, and a?=2 3°.

But this is impossible, since one square cannot be double of another, in integer
numbers.

Haamples. 5°=4? +3, and 3 being prime, we have 5—4=1.

Again, 13?=12?+5?, and 5 being prime, we have 13—12=1.

Again, 25°=24?+72, and 7 being prime, we have 25—24=1.

The converse, however, is not true. For if a?=?+c?, and a—b=1, it by no
means follows that either 6 or cis a prime. For example, 221?=220?+212, none
of which numbers are primes.

Ten <s OR gt) (ia wate

( 407.)

XXVIII.—On a Proposition in the Theory of Numbers. By BatFrour STEWART,
Esq., of the Kew Observatory.

(Read 21st April 1856.)

Problem. If p be one of the roots of the equation «—1=0, (not 1,) then
(1—p)(1—p”). . . . (1—p™~+)=m, provided m is a prime number.

If m be not a prime number, and if p,=cos = /—1 sin aa the same will
hold for all roots p=p,”, where a is a number <m and prime to m. But for all

roots p=p,”, where a, or one of its prime factors, is also a prime factor of m, the
product (1—p) (l—p”) ... . (—p™—1) will be equal to 0.

Preliminary Propositions.

I. If m be a prime number, and a, 6 two numbers, each less than m; and if
a@=ym+0, where 0 is less than m; then 0 is neither equal to a nor to @.

For if 0=a, we shall have a (G—1)=ym, where a and 6—1 are both less than
m, Which clearly violates the well-known theorem that a number cannot be made
up in two ways of prime factors.

If. Again, ifa(6+6,)=y, m+0, (where G+, <m); then 6, is not equal to 6.
For if 6,=0, then a (@+@,) =y,m+6
=(Wi- VY) m+yms+
=(y¥,-y) +48
therefore aC, =(¥,-Y)
or a number is made up in two ways of prime factors, which is impossible.
III. If, therefore, we arrange in a horizontal row all the numbers in order of

magnitude from 1 to m—1 inclusive, and the same in a vertical row downwards,
so that the two columns shall form the adjacent sides [T_— a

: C A L) 2 3. 4S “6
of a square, and if we multiply each successive number 9
in the top horizontal column by the number in the ver- Pa 4
tical (as in the multiplication table), divide the product
. : 4 3
by m, and write down the remainders: then none of these P
remainders will be the same, for they will not be the | ,

multiplier itself (Prop. I.), nor, 2°, will any two be alike ee

(Prop. II.). The multiplier and remainders will contain all the numbers from
VOL. XXI. PART III. Ds

408 BALFOUR STEWART, ESQ., ON A PROPOSITION

1 to m—1 inclusive, though not in order of magnitude. We have exhibited this
in the margin for m=7, the multipliers being 3 and 4.

IV. If m be not a prime, but composed of the prime factors axbxex
dxexfx ...., and if aor one of its prime factors (/) be also one of the prime
factors of m, then in some case will aG=y™m, where @ is one of the numbers
193) eT ae

For 7 and 7 are whole numbers <m; anda. = . m, Which satisfies the

condition.

V. If neither a nor any of its prime factors is also a prime factor of m, then
there will be a remainder 6 <m whatever be .

For if not, let aB=ym; then since m>@..y<a. Therefore y is either
prime to a, or there is a factor in a which is not in y: but this factor is, by hy-
pothesis, not in m: it is, consequently, not in ym, which is absurd.

VI. The remainders will be different for every different value of 6. For
if possible, let a B=ym+0

a(B+6,)=y¥, m+o.

=(y,—y) m+aB
therefore, a 6,=(y,—‘y) m which, as in the last Prop., is impossible.

VII. If, then, we arrange the numbers as in Prop. II.,
we shall have 0 amongst the remainders, for all values
of a which either divide m, or have a prime factor in com-
mon with it; whilst, for all other values of @, we shall
have the same results as in Prop. III. This is shown for
m=8 in the margin, for the multipliers 3, 4, and 6.

Problem 1. If m be a prime number, the roots of the equation #™-1=0 are

1, Pp Pp? - ++ pm—1 where p, =cos ae Gay Sa sin 27
For, from the theory of equations,
2” —1=(e~1) (@—p,) (@—p2) » » . (@—p,"-})
or MgO OE ois +1=(a—p,) (w@—p,2)...
putting 1 for a, m= (I—p,) (1—p,?).. . . d—p,2-.
If P=P\” since ps. pym=l;

and if a B=ym=0) eo =P,

IN THE THEORY OF NUMBERS. 409

hence, dp, G=p2")- 22 dp, will be thesame as

(1—p,”) dpi)... (L—p,"~9),
where 6,, 6,, &c. are the remainders. But, by Prop. III., 6, 6,, &c., are all different,

and are the numbers 1, 2, . . . m—1: hence,
Ger). Ad" )=C =p") =p," *)- - -
=(1—p,)\(1=p,7). .-d—p,"~"*)
=m,

Problem 2. If m be not a prime number, the same equation is true, by Prop. VII.,
for p=p,*, where a is less than, and prime to m; but if a or one of its prime factors
is a prime factor of m, then one of the factors (1— p,”) (l—p,2%) . . . —p,(™7 1")
will be of the form 1—p,7”=0; and, consequently, the product itself will be
equal to 0.

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(atid

XXIX.— On the Prismatic Spectra of the Flames of Compounds of Carbon and
Hydrogen. By Witi1aM Swan, F.R.S.E.

(Read 21st April 1856.)

The phenomena presented by the prismatic spectra of flames have occupied
the attention of many and excellent investigators. In most instances, however,
no attempt has been made to procure accurate measurements of the positions
of the bright lines which many of the spectra exhibit; and much in this field
of observation, therefore, remains to be accomplished. I purpose, from time to
time as I shall have leisure, to make a series of observations, whose object shall be
the actual numerical determination of the positions of the bright lines in the
spectra of flames; and I have commenced the series with an examination of
the spectra of the flames of compounds of carbon and hydrogen. In an in-
vestigation into the phenomena, of flames, the compounds of carbon and hydro-
gen claim our first attention, as constituting the most important means of
artificial illumination; for it is scarcely necessary to remark, that, with the
grand exception of sun-light, the combustion of these substances is the source
of nearly all the light and heat from which we derive such extensive benefits
in the arts and in domestic economy. It will be found, moreover, that the spectra
of carbohydrogen fiames possess, in common, remarkable features, which seem as
yet to have received little attention, but which promise to be of service in ex-
plaining the general phenomena of artificial light.

If we examine the spectrum of the brightest part of the flame of an oil-lamp
or a tallow-candle, it will be found that it exhibits no dark intervals, and that
its colour and brightness vary gradually from point to point with scarcely any
breach of continuity. If, however, we observe only the light proceeding from the
blue part of the flame, which surrounds the upper part of the wick, a totally
different result is obtained. The extreme red and violet rays become nearly or
altogether invisible, and the intermediate portion of the spectrum exhibits a
series of bright lines separated by dark intervals.* Similar lines occur in
the flames of alcohol, sulphuric ether, and wood spirit. They are seen, how-
ever, with great difficulty in the flame of impure wood spirit, and are scarcely, if
at all visible, in the more luminous flames of oil of turpentine and coal naphtha.
Before offering an explanation of these differences, it will be necessary to premise
some particulars regarding the nature of flame.

* For descriptions of lines in the spectrum of an oil lamp flame, see Fraunnorer, Astronomische
Abhandlungen, 1823, p. 16; Herscuet, Edin, Trans., vol. ix., p. 455, and article Light, Encyc.
Metrop., art. 522. The spectrum of the blowpipe cone is described by FraunHoFER, BREWSTER’S
Journal of Science, vol. vii., p. 7; and by Drarer, Phil. Mag., vol. xxxii., p. 111.

~

VOL. XXI. PART ITI. oT

412 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

On the Nature of Flame.

We owe to Hooxg, probably the first careful inquiry into the constigition of
flame. More recently, the subject has been studied by Sir Humpury Davy and
Professor DrRAPER.*

The flame of coal gas or of a common candle, as is well known, consists of
several portions, readily distinguishable by the eye, and in which the matter
composing the flame exists in very different conditions. ‘There is, first, the inte-
rior non-luminous portion, composed of gases not yet ignited; secondly, a blue
conoidal shell, near the wick or burner, which, as it extends upwards, seems gra-
dually to change its colour to a brilliant yellowish white; and, thirdly, an outer
mantle or envelope of faintly luminous matter. On a careful examination, it
will be found that the blue cone envelopes the white one; the blue, gradually
thinning out towards the top, and the white, towards the bottom of the flame.

It has been supposed that, in the blue portion of the flame, the supply of oxy-
gen is sufficient to insure the complete combustion of the gases, so that, in a
carbohydrogen flame, there is the immediate production of water and carbonic
acid.+ The bright white light of the upper portions of the flame was proved by
Sir Humpury Davy to proceed from the separation of solid carbon, which becomes
brilliantly incandescent at the high temperature to which it is exposed, and
which, when not converted into carbonic acid, escapes in the form of smoke.

The external mantle of the flame, according to Professor DraprEr, derives its
light chiefly from incandescent carbonic acid and aqueous vapour.

While in the ordinary flames of coal gas and oil, solid carbon is separated, it
is well known that by burning a mixture of gas and air, the separation of carbon
may be entirely prevented, and a smokeless flame obtained. My attention was at
first accidentally directed to the subject of this paper while using a species of
gas lamp in which this object is effected in a very simple manner. As this
lamp—the invention of Professor Bunsen of Heidelberg—has only lately been
introduced { into this country, and as I have made extensive use of it in my ex-
periments, it may be proper to explain its construction.

It consists of a common “union” or “bat-wing” gas burner, which, when
used in the ordinary manner, would produce a flat, fan shaped flame. The
burner is surrounded by a brass tube, 0°4 inch in diameter, and about 3 inches in
height, having apertures immediately below the burner, which can be opened or
closed, so as to admit aregulated supply of air. The gas issuing from the burner
in a fan shape strikes obliquely the walls of the tube, and being reflected from

* Works of Sir H. Davy, vol. vi., Lond. 1840. Drarsr on the Production of Light by Chemical
Action, Lond. Phil. Mag., 1848, vol. xxxu., p. 100.

+ Kanz’s Chemistry, p. 289.

t By Dr Rozerr Fercuson, whose interesting account of the la amp will, I believe, appear in the
iansdcwions of the Royal Scottish Society of Aris.

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 413

them, becomes effectually mixed with the air which enters at the bottom; and the
mixture of gas and air, when lighted, burns at the top of the tube with a volu-
minous flame, without smoke. A thorough mingling of the gas and air is essential
to the success of the arrangement, which will be found to fail when a plain burner
is substituted for the “ wnion jet.”

The flame of the Bunsen lamp consists of at least two distinct portions,—a
luminous hollow cone of a strong bluish green colour, about two inches in height,
and avery diffuse outer mantle, about 6 inches in height, reddish towards the
interior, but externally of a pale lavender tint. In this, also, as in the ordinary
flame of coal gas, but in much greater profusion, there is a perpetual scintillation
of yellow sparks, arising apparently from foreign matter suspended mechanically,
partly in the gas, and probably more abundantly in the air which enters the tube
and mingles with the gas before combustion. This matter is projected continually
through the walls of the flame, where it becomes for a moment incandescent.*

The light of the exterior envelopes of flames, is, I conceive, chiefly due to the
presence of minute particles of solid matter, derived partly from the substance
undergoing combustion, and often, as in the case of the Bunsen lamp, from the
air which enters the flame. The outer envelope of the flame of the Bunsen lamp
possesses so little inherent luminosity, that it is peculiarly susceptible of having
its colour influenced by the accidental presence of foreign matter. As the salts
of sodium are well known to be remarkably energetic in producing homogeneous
yellow light, I made the following experiment, in order to ascertain how small a
portion of matter could in this way render its presence sensible.

One-tenth of a grain of common salt, carefully weighed in a balance indicating
70 Of a grain, was dissolved in 5000 grains of distilled water. Two perfectly
similar slips of platinum foil were then carefully ignited by the Bunsen lamp, until
they nearly ceased to tinge the flame with yellow light; for to obtain the total
absence of yellow light is apparently impossible. One of the slips was dipped into
the solution of salt, and the other into distilled water, the quantity of the solu-
tion of salt adhering to the slip, being considerably less than 3g grain, and both
slips were held over the lamp until the water had evaporated. They were then
simultaneously introduced into opposite sides of the flame; when the slip which
had been dipped into the solution of salt, invariably communicated to a consider-
able portion of the flame a bright yellow light, easily distinguishable from that
caused by the slip which had been dipped into pure water. It is thus proved,
that a portion of chloride of sodium, weighing less than UH of a grain is able

* Tf the air be dusty from any cause, these scintillations become very abundant. Thus, i° the
floor be swept, or a piece of charcoal be scraped with a knife at a little distance from the lamp,
minute particles are carried by the current of air into the tube, and cause a profusion of sparks, which
exhibit a very beautiful appearance, while they confirm the opinion that the ordinary sparks are oc-
casioned chiefly by particles of dust carried by the air.

414 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

to tinge a flame with bright yellow light; and as the equivalent weights of sodium
and chlorine are 23 and 35:5, it follows, that a quantity of sodium not exceeding
2 s00KD of a troy grain renders its presence in a flame sensible. If it were possible
to obtain a flame free of yellow light, independently of that caused by the salt
introduced in the experiment, it is obvious that a greatly more minute portion of
sodium could be shown to alter appreciably the colour of the flame. It therefore
follows, that much caution is necessary in referring the phenomena of the spectrum
of a flame to the chemical constitution of the body undergoing combustion. For
the brightest line in the spectrum of the flame of a candle,—the yellow line R* of
FRAUNHOFER,—can be produced in great brilliancy, by placing an excessively
small portion of salt in a flame, in whose spectrum that line is faint or alto-
gether absent. The question then arises, whether this line in the candle flame
is due to the combustion of the carbon and hydrogen of which tallow is chiefly
composed, or is caused by the minute traces of chloride of sodium contained in
most animal matter. When indeed we consider the almost universal diffusion of
the salts of sodium, and the remarkable energy with which they produce yellow
light, it seems highly probable that the yellow line R, which appears in the
spectra of almost all flames, is in every case due to the presence of minute
quantities of sodium.

The view, which would attribute a great portion of the light of the envelopes
of flames to the adventitious presence of minute traces of foreign matter, may
possibly serve to explain certain anomalous diversities of colour which are
observed in the envelopes of flames arising from the combustion of the same ele-
ments. Thus tallow, coal gas, anhydrous alcohol, and weak spirit of wine, all
contain the same combustible substances, carbon and hydrogen: yet the envelope
of the flame of a candle is bright yellow, that of a coal gas flame is purple, and
those of strong alcohol and weak spirit differ greatly in luminosity.

It is important also to remark, that while the luminosity communicated to
the exterior envelope of a flame by such substances as the salts of sodium or of
copper, may be so great as to disguise that of the inner bright cone of the flame,
or in some cases to render it altogether invisible; yet I have ascertained that the
light of the blue portion of the flame, or of the inner cone, remains absolutely
unchanged in colour and intensity. The proof of this curious property of flame
will be given in the sequel.}

Prismatic Analysis of Flame.

Reserving, meantime, a more complete description of the apparatus I have
employed, it may be sufficient to premise, that, in what I shall have to say regard-
ing the spectra of flames, the object observed is supposed to be a narrow illumi-
nated slit, viewed through a glass prism mounted before a telescope, which has
been adjusted to focus on the slit.

* Scnumacuer’s Astronomische Abhundlungen, 1823, p. 18. t See p. 419.

_ ee a

_ ’
ee eS! ee ee ee

2
i

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 415

It has already been stated, that certain carbohydrogen flames afford spectra
exhibiting bright lines separated by dark spaces. In no spectrum are these lines
more easily observed than in that of the Bunsen gaslamp. In order to distinguish
the phenomena of the spectrum which are due to different portions of the flame, it
is sufficient to place the lamp before a narrow vertical slit not exceeding 0:2 inch
in height, through which its light passes to the prism.* If the lamp be gradually
raised before the slit, the spectrum first seen will be derived exclusively from
the envelope of the flame, which reaches high above the top of the interior cone.
This spectrum is tolerably bright, extending without the least interruption, from
the line C, nearly to the line H of Fraunuorer, and exhibiting no bright line
whatever except the yellow line R. That line, however, is extremely flickering,
so as often to disappear completely ; and it seems due entirely to the yellow scin-
tillations which abound in the exterior envelope. When the flame is raised still
higher, so as to bring the top of the green cone into view, four other bright lines
begin to appear; and as we continue to raise the flame so as to derive light from
lower and lower-portions of the flame, the bright lines become more and more
clearly defined, owing to the intervening spaces becoming darker ; and some fainter
lines become visible. At length, when light passes through the slit only from the
lowest portions of the flame where the exterior envelope nearly disappears, the
bright lines become so sharply defined as to admit of their places being ascer-
tained by actual measurement, with almost the same accuracy which is attainable
in observations of the dark lines of the solar spectrum.

From the facility with which the lines of the carbohydrogen spectrum are
obtained, I conceived they might be of use in optical researches; and I soon
found them of great service in the prosecution of my experiments. I was, there-
fore, anxious to ascertain whether they belonged really to the gas flame, or were
caused by the accidental presence of foreign matter; for it is well known that
some metals, such as copper, when present in a flame, produce bright lines in
its spectrum. for this purpose I burned a mixture of coal gas and air, succes-
sively, from an iron tube, a glass tube, a tube formed of a coil of platinum foil,
and the brass tube of the Bunsen lamp; but in every case the lines remained
unchanged in number and position, proving that they arose entirely from the
combustion of the gas, and not from any matter derived from the lamp.

On the Apparent Diversity of the Spectra of Compounds of Carbon and Hydrogen.
Having thus studied the general phenomena of the spectra of carbohydrogen
flames, some of which exhibit continuous, and others interrupted spectra, we may
now resume the question, Whence do these differences arise ? .
It has been found by Professor DraPer that an incandescent solid body emits
* Or we may adopt Professor Drapzr’s ingenious mode of observing flames through a horizontal
slit, Phil. Mag., vol. xxxii. p. 106.
VOL. XXI. PART III. 5 U

416 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

light of every degree of refrangibility between limits varying with its temperature.
Thus, when carbon burns in oxygen, or when a strip of platinum is heated, to a
temperature of 2130° Fahr., by the passage of a current of electricity, a perfectly
continuous spectrum is produced, without any bright lines or dark spaces, and ex-
tending at least from the line B to the line H of the solar spectrum.* This enables
us to explain why we may see, in the spectrum formed by the blue portion of a
flame, bright lines and dark spaces, which are totally invisible in the spectrum of
the bright inner cone. For the light of the inner cone arises from incandescent solid
carbon deposited in the flame, which, as we have just now seen, must produce a
brilliant continuous spectrum. The light of this spectrum overpowers the compa-
ratively faint illumination of the bright lines of the spectrum formed by the blue
part of the flame, while it fills up the dark intervals between them; and both
causes conspiring render the lines invisible. Again, lines may easily be seen in
the spectrum of the blue part of a spirit lamp or candle flame, which fail to show
themselves when we examine the flames of oil of turpentine or coal naphtha; for
the latter bodies contain so much carbon that it begins to be deposited almost at
the very bottom of the flame. The blue conoid is thus reduced to an extremely
narrow ring; and it is practically impossible, however small the aperture through
which light passes to the prism, to obtain the spectrum of the blue light separated
from that of the incandescent carbon.

We can also similarly explain why lines may be visible in the spectrum of
alcohol, which may not be easily seen in that of weak spirit of wine, or of im-
pure wood spirit. The exterior envelope, like the interior bright cone, derives
most of its light from incandescent solid matter, and produces a continuous spec-
trum, as was shown in the case of the Bunsen lamp. Now the exterior envelope
of the flame of weak spirit of wine, or of wood spirit, is very voluminous and
fully developed, and hence of unusual thickness near the bottom of the flame.
The light derived from the incandescent matter it contains, will therefore operate
precisely like that of the interior luminous cone, in rendering the bright lines of
the spectrum invisible.

On Methods of Observing the Spectra of Carbohydrogen Flames.

Since the continuous spectra due to the light of incandescent matter offer
no distinguishing features, it follows, that in searching for phenomena charac-
teristic of the chemical constitution of bodies undergoing combustion, we must
examine that part of the flame in which any solid molecules, which are being de-
posited, have not been able to collect into masses. This state of things exists in
the blue portion of the carbohydrogen flames, where the supply of air is sufficient
completely to consume the gases. In flames, such as that of oil of turpentine,
C,, H,, where there is much carbon, it becomes necessary to burn the carbon by an —

* Phil. Mag., rol, Xxx., p. 349.

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 417

artificial supply of air. Two methods occurred to me of effecting this object, so as
to convert the carbon into carbonic acid, without its intermediate separation in a
solid form. One was to burn the vapours of the substances under examination
in the Bunsen lamp; but this I rejected as inconvenient, and perhaps even in
some cases dangerous, from the risk of explosion, where it would have been
necessary to boil highly volatile liquids in close vessels. The other was simply
to pass a stream of air through the flame by means of a table blowpipe. By
means of the latter expedient I succeeded so completely in preventing the sepa-
ration of solid carbon, as to obtain spectra with bright lines and dark spaces,
in the case of every compound of carbon and hydrogen which I have as yet sub-
mitted to examination.

Comparison of the Spectra of the Flames of various Substances containing Carbon and
Hydrogen.

The hydrocarbon compounds which I have examined, and which are enu-
merated in the following table, may be divided into two classes; one consisting
of substances containing only carbon and hydrogen, of which the general formula
is C,H,, and the other of substances containing carbon, hydrogen, and oxygen,
represented by the formula C, H, O,.

C, Hs
Light carburetted hydrogen,
Olefiant gas, : ;

Parafiin, ’
Oil of turpentine,

i]

bo
o
bo
o

AAA

“bo bo bo

C, H, O;

Methylic alcohol, A . ‘ : 2 C
Alcohol, : : : ; : . C
Ether, , : F é é : Cc
Methylic ether, . ; ; : : : C
Glycerine, . :

Spermaceti, ; ; : 3 f
Camphor, : ; : ; < , Cc
Wax, ; 4 s j : : 5
Tallow, . ; : 2 3 : : Of indefinite
Coal gas, . . : : : : : composition.

Coal naphtha,

own,
oO bo

ooo ee

O09 SPOOLS

aD
oO
rs

Of these substances, the light carburetted hydrogen was made by heating
acetate of soda, hydrate of potassa, and quicklime ; and the methylic ether from
‘wood spirit and sulphuric acid. The gases were generally burned from a platinum
jet, immediately after passing through a tube filled with pieces of quicklime.
The glycerine, a substance which burns with difficulty, was heated in a platinum
capsule; and the paraffin, camphor, and spermaceti, which were colourless, crys-
talline, and apparently pure specimens, were also similarly treated, in order to cor-
roborate the conclusion stated at p. 415, that the lines observed in the spectra were

418 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

all due to the combustion of the carbohydrogen compounds, and not to the pre-
sence of foreign matter. The alcohol, ether, and other liquids, were burned in
lamps made of small phials,—a glass tube furnished with a cotton wick serving
as a burner.

Taking the spectrum of the Bunsen lamp as a standard, the spectra of the
other flames were compared with it, by viewing both simultaneously,—the light
from the two flames passing through the same narrow slit.

The result of this comparison has been, that, in all the spectra produced by
substances, either of the form C, H, or of the form C,H, 0,, the bright lines have
been identical. In some cases, indeed, certain of the very faint lines, which occur
in the spectrum of the Bunsen lamp, were not seen. The brightness of the lines
varies with the proportion of carbon to hydrogen in the substance which is burned,
being greatest where there is most carbon. Thus, in the spectra of light carburet-
ted hydrogen, pyroxylic spirit, and glycerine—substances which contain compa-
ratively little carbon—certain of the fainter lines of the Bunsen lamp spectrum
were not seen; but-all those that were seen were identical with the lines of the coal-
gas flame. I have no doubt that the fainter lines were really present, but were
invisible, merely owing to their feeble luminosity; and this is rendered more pro-
bable by the fact that the number of lines visible in any spectrum varies with the
brightness of the light. Thus in the solar spectrum, or in that of the Bunsen
lamp, the fainter lines disappear when the intensity of the light is diminished.

The absolute identity which is thus shown to exist between the spectra of
dissimilar carbohydrogen compounds is not a little remarkable. It proves, 1s¢,
that the position of the lines in the spectrum does not vary with the proportion
of carbon and hydrogen in the burning body ; as when we compare the spectra of
light carburetted hydrogen, C H., olefiant gas, C, H,, and oil of turpentine, C,, H,;
and, 2dly, that the presence of oxygen does not alter the character of the spec-
trum ; thus, ether, C, H, O, and wood spirit, C, H, O,, give spectra which are
identical with those of paraffin, C,, H,,, and oil of turpentine, C,, H,.

In certain cases, at least, the mechanical admixture of other substances with
the carbohydrogen compound does not affect the lines of the spectrum. Thus I
have found that a mixture of alcohol and chloroform burns with a flame having
a very luminous green envelope—an appearance characteristic of the presence
of chlorine—and no lines are visible in the spectrum. When, however, the flame
is urged by the blowpipe, the light of the envelope is diminished, and the ordinary
lines of the hydrocarbon spectrum become visible.

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 419

Comparison of the Carbohydrogen and Solar Spectra.

Having ascertained, that probably all substances of the forms C, H, and C, H, O,
produce, when burning, spectra which are absolutely identical, I was desirous to
compare their spectra with that of sun light.

For this purpose I at first attempted to view the solar spectrum and that of
the Bunsen lamp simultaneously, but the great comparative faintness of the lat-
ter rendered that mode of comparison exceedingly difficult. I therefore deter-
mined to measure separately the minimum deviations for the principal lines of
the solar and gas spectra; the intervals between the adjacent smaller lines of the
latter spectrum being ascertained by means of a micrometer.

The instruments I employed were an excellent theodolite by Apis, and a very
fine flint-glass prism by Srcreran of Paris, whose faces have an area of four
square inches, and which shows, with great distinctness, the finest lines in Fraun-
HOFER’S map of the solar spectrum. Iam indebted for the use of these instru-
ments to the kindness of Mr Joun Avie and Professor Fores.

The prism being placed in its position of minimum deviation, the indices of
refraction given in the sequel were calculated by the formula

_ sin3(1+D),
Tae iy aria
where I is the angle of the prism, and D the deviation of the transmitted light.

I have denoted the five brightest lines of the carbohydrogen spectrum by the
letters, a, 8, y, 0, @; and the fainter lines by which they are accompanied by £,, (,,
y,, &c. Inthe tables, Dy, D,, 1s, u, &c., denote respectively the minimum devia-
tion of the rays, and the index of refraction for the lines A and y of the solar
and flame spectra.

A comparative diagram of the spectra of sunlight and the hydrocarbon flames
is given in Plate VIII., fig. 1, where a is the double yellow line R of FRauNHOFER.
I have thought it advisable to introduce this line in the diagram, as it is almost
constantly visible in ordinary artificial light, although, for reasons already fully
stated, I conceive it is not peculiar to the spectra of carbohydrogen compounds.
This conclusion is strongly corroborated by the remarkable phenomena pointed
out at p. 414, namely, that the salts of sodium tinge the exterior envelope of
the Bunsen lamp flame with so brilliant a yellow light, as completely to over-
power the comparatively feeble blue light of the inner cone, and to render it al-
together invisible; while yet the light of that portion of the flame remains abso-
lutely unchanged. This remarkable property of flame is easily demonstrated by
. holding a slip of platinum, with some salt placed on it, in the flame, while the
Spectrum is observed through a telescope. The instant the salt reaches the flame,
the yellow line R or a, which before may have been extremely faint, or altogether

VOL. XXI. PART III. . ok

420 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

imperceptible, shines out in great brilliancy; while the lines £, +, 6, and ¢ remain
totally unchanged in position, colour, and intensity.

While the line a is thus exceedingly variable in its brightness, the lines @, y, 6,
and ¢, on the other hand, are perfectly steady; and being never absent in
carbohydrogen spectra, there is every reason to believe that they are really
characteristic of the body undergoing combustion. Beyond a on the less refracted
side there is a faint trace of red light, which, as it becomes so feeble as almost to
disappear when the light is derived from the lowest point of the flame of the
Bunsen lamp, is probably due to the exterior envelope of the flame, and not to
the interior cone. The line a is separated from 6 by an extremely dark space,
almost destitute of light. The line @ is of a faint yellowish green colour, but well
defined, and is accompanied by four almost equidistant lines 6, 6,, &c., which
diminish in brightness as their distance from @ increases. After another very
dark interval, the extremely beautiful line y follows, which is exceedingly bril-
liant, and of such absolutely definite refrangibility as, like a, to form a perfectly
sharp image of the slit through which the light passes. Its colour is a fine
slightly bluish or pea green, and it is accompanied by a fainter line y,. The
next line 6 is the less refracted edge of a broad band of light containing four
fine lines. This group, which is of a pale ashy colour, is separated by dark in-
tervals from Y and Z. The line ¢ belongs to a brilliant but not very well defined
band of a fine purple tint, which is accompanied by a fainter line e.

I have completed observations of the minimum deviations for the lines a, 8, ¥,
6, and ¢; and also for the principal lines of the solar spectrum, which are given in
Series 1, Tables II. and II1., pp. 427, 428. From an examination of these tables it
appears, that while several lines in the carbohydrogen spectrum coincide nearly in
position with remarkable lines in the solar spectrum; yet in no case, if we except
the line a, has the observed coincidence been exact. The observations, therefore,
rather tend to prove that the bright lines of the carbohydrogen spectrum coincide,
not with the dark lines, but with the bright spaces of the spectrum of sun light.

Postscript added since the preceding Paper was read.*

From the well known coincidence discovered by FRAUNHOFER, to exist between
the line R, in the spectrum of a lamp, and D of the solar spectrum, taken in con-
nection with similar phenomena, which have since been observed, it might be
inferred, as a general law of the spectra of flames, that their bright lines always
coincide with dark lines of the solar spectrum.

The result of the investigations which have now been detailed, is obviously
unfavourable to such a conclusion. In publishing observations bearing on a ques-
tion of so much interest and importance, I was anxious, if possible, to leave no

* Printed by permission of the Council.
*

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN, 421

doubt as to their accuracy ; and since the preceding paper was read, I have made
a much more extensive series of experiments, than the limited time I can devote
to such researches, had then enabled me to overtake, involving the determination,

with more or less accuracy, of the positions of all the bright lines in the carbo-
hydrogen spectrum, whose presence I have been able to detect. These experi-
ments, with some account of my methods of observation, I have deemed it desirable
to append to the preceding paper.

Methods of Observation.

The theodolite A, fig. 2, which was used in measuring the deviations of the
refracted rays, has a limb 7°5 inches in diameter, with two verniers reading 10”,
and a telescope B, of 1:6 inch aperture, furnished with a parallel wire micro-
meter. The stage carrying the prism P, furnished with screws to render its faces
perpendicular to the divided circle, was mounted over the centre of the theodolite ;
and, in order to avoid parallax, the object viewed was an extremely narrow slit
placed in the principal focus of the object glass of a 30 inch telescope CL,
which thus acted as a collimator.* The telescope rested in Ys, in a solid cast-
iron stand, D D, which also carried the theodolite: so that the collimator pre-
served an invariable position in relation to the theodolite, notwithstanding any
instability of the floor of the room in which the observations were made; and the
zero of the circle was found to remain exceedingly constant. A diaphragm with
a vertical slit was placed before the collimator lens, so as to limit the aperture in
the plane of refraction to 0-4 inch, and thus to allow only a nearly central pencil
of rays to fall on the prism. Any errors, which might have arisen, either from
imperfect adjustment of the collimator to sidereal focus, or from defective aplana-
tism in its lens, were thus avoided as much as possible.

The deviations of the refracted rays were observed first to the right, and then
to the left,—the prism being always adjusted to its position of minimum devia-
tion,—so that the difference of the readings of the verniers in the two positions of
the prism, gave double the minimum deviation of the refracted rays.

The angle of the prism was ascertained, by first turning it with its edge to-
wards the object glass of the telescope, as represented in fig. 3, where ABC is the
prism, and T the telescope. The stage carrying the prism was rigidly connected
with the telescope, so that when the telescope was moved, the prism moved along
with it; and being left undisturbed, the inclinations of its faces AB, AC, to the
line of collimation of the telescope remained invariable. The telescope was then
turned, until the image of the illuminated slit of the collimator, seen by reflection,
successively in the two faces of the prism, was made to coincide with the tele-
scope wires; and, at each intersection, the verniers were read off. The difference

* I have’ described this mode of observation in my paper on the Ordinary Refraction of Iceland
Spar, Edin. Trans,, vol. xvi,

422 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

of the readings then gave double the angle of the prism. For, if DGI, FHK re-
present the course of the reflected rays, since the telescope has been adjusted to
sidereal focus, GI and HK, must be parallel; and the angle DEF, will obviously
be double the angle BAC. Now, since DE and EF, are at the times of ob-
servation successively in the same direction, namely, that of the parallel rays emerg-
ing from the collimator, it follows that the telescope must have been turned
through the angle DEF. Hence the difference of the readings is DEF, or twice BAC.

In order to test the adjustment of the collimator to sidereal focus, I made two
series of observations of the angle of the prism given in Table I.; Series I. having
been made by means of the collimator, and Series II. on a definite point of the
tower of St Stephen’s Church, distant about 2240 feet, where the parallax due to
any difference in the directions of the rays incident on the two faces of the prism
could not have caused an error exceeding 4” in the measured angle.

These results agree so closely as to show that any want of parallelism in the
rays emerging from the collimator, arising from want of perfect adjustment to
sidereal focus, could not have appreciably affected the observations of the absolute
deviations of the refracted rays. I may also observe, that since, during the ob-
servations of the carbohydrogen and solar spectra, the whole apparatus remained
unaltered, any want of parallelism in the rays incident on the prism, whether aris-
ing accidentally from imperfect adjustment of the collimator, or necessarily from
the unavoidable want of perfect achromatism in its lens,—for either cause might
modify the apparent direction of the observed object, if the pencil of rays incident
on the prism were not accurately central,—would affect the observed deviations in
the two spectra alike. The accuracy of the observations, viewed merely as afford-
ing a comparative view of the relative positions in the scale of refrangibility occu-
pied by the lines in the two spectra, would thus remain entirely unimpaired.

I have ascertained, however, by actual experiment, that the observations of
absolute deviation cannot have been sensibly affected by any want of achromatism
in the lens of the collimator. Having caused the telescope wires to coincide ac-
curately with the image of the collimator slit, I illuminated the slit alternately
with the extreme red and the extreme violet rays of the solar spectrum formed
by a flint-glass prism. I then found that the image of the slit did not in the
slightest perceptible degree alter its apparent position; so that, while the illumi-
nation was changed from red to violet light, the wires continued to bisect the slit
with perfect accuracy.

As the spectrum of the Bunsen lamp is so faint that the telescope wires, when —
projected on all but its brightest lines, are invisible, it became necessary to illu-
minate the wires; but I speedily found that, from the feeble luminosity of the
spectrum, observations with an illuminated field were nearly impracticable,
and I was therefore obliged to observe with illuminated wires on a dark field.
The arrangement for illuminating the wires which I devised is so simple, and —

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 423

proved so successful, that I venture to describe it, in the hope that it may prove
useful in similar researches. A hole, @ (see fig. 4), 0-1 inch in diameter, was
drilled in the side of the tube in which the eye piece slides, at a point between the
field lens of the eye piece and the wires ~; a small lamp, L, furnished with a
condensing lens c, and a conical tube with a small aperture e, through which
alone light was allowed to pass, was attached to the telescope, so that the light,
indicated by 77, emerging from the conical tube, and entering the hole in the
eye piece tube, crossed the axis of the telescope at an angle of about 70°, so as to
illuminate the intersection of the wires at , on the side neat the eye, while all the
rest of the field remained perfectly dark. By slightly varying the position of the
lamp, the illumination of the wires could be adjusted with the utmost nicety to.
suit the brightness of that portion of the spectrum which was under examina-
tion.

Notwithstanding the most careful adjustment of the illumination of the wires,
I still found the observation of the fainter lines of the carbohydrogen spectrum
extremely difficult. The brightness of the lines in the spectrum of the Bunsen
lamp is, however, considerably augmented by urging the flame by the blowpipe;
and I found it useful to employ three jets placed one behind another, so that the
combined illumination of three blowpipe cones might fall upon the prism. This
apparatus, which is useful in exhibiting the fainter lines of the carbohydrogen
spectrum, is easily constructed by forming three blowpipe jets of glass tube, about
0:2 inch in diameter, in the ordinary manner, and placing them, side by side, in
a perforated cork. The cork is then inserted in a short piece of wide tube, having
at its other end a second cork, connected with a flexible tube conveying a current
of air from a table blowpipe.

I have also carefully compared, by simultaneous observations, the spectrum
of the Bunsen lamp flame urged by a jet of oxygen gas, with the spectrum ob-
tained by means of the triple air blowpipe. The lines in the two spectra were
almost equally bright, and differed neither in number nor in position.

In the observations, Series I., Tables II. and III., I used an eye piece giving a
magnifying power of 11, which was afterwards superseded by another magnify-
ing 21 times, with which Series II. was made.

Comparison of the Carbohydrogen and Solar Spectra.
The second series of observations having been made with a higher magnify-
ing power, and in some other respects also in more favourable circumstances
than the first, is to be regarded as more trustworthy ; yet the results of both agree

_ 8o closely, that any additional accuracy which might have been obtained by as-

certaining, separately, the probable errors of the two series, and their most pro-

bable result, when combined, could scarcely have repaid the labour of the neces-

sary computation. I have, therefore, deemed it sufficient to give all the observa-
VOL. XXI. PART III. 5 Y

424 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

tions equal weight, and to take simply the arithmetical mean of the whole. The
mean results of the two series, and the number of observations in each, being
tabulated separately, the reader will be able to form some judgment regarding
the probable accuracy of the final determinations obtained from the two series
combined. In Fig. 1, which is a graphic construction of the observations in
Tables II. and III., the lines were drawn by the engraver through points laid
down by me on the copper to a scale,—adopted to suit the size of the plate,—of
one inch to 2200”. I have ascertained the errors in the positions of these lines
to amount, in one case only to ‘01 inch (corresponding to 22”), and to be generally
much less; so that the spectra are represented in the figure with tolerable
fidelity.

In addition to the observations of the carbohydrogen and solar spectra con-
tained in Table II., where the deviation for each line of either spectrum was
separately determined by the theodolite or micrometer, I have also made simul-
taneous observations of the spectra of sun light and of olefiant gas. The gas, which
was prepared by heating alcohol with sulphuric acid, was conducted through
wash bottles containing caustic potash and sulphuric acid, to a gas holder; from
which it afterwards passed, through a tube filled with pieces of quicklime, to a
platinum jet where it was burned.

The lines in the spectrum of olefiant gas are very distinct, being well seen
without using the blowpipe ; but like the lines in the other carbohydrogen spectra,
they are not sufficiently luminous to be seen when projected on the solar spectrum,
unless the Jatter is made so faint, that its lines have disappeared. I succeeded,
however, in observing the spectra simultaneously, by intercepting the sun light
which fell upon one half of a narrow slit, and illuminating the whole slit with
the flame of olefiant gas. The gas spectrum then appeared immediately over that
of the sun, and the brighter lines in it were well seen, especially when the flame
was urged by the blowpipe. The intervals between the lines of the gas spectrum
and the nearest lines of the solar spectrum, given in Table V., were measured by
the micrometer, with a magnifying power of 21; and the observations for the
brighter line 6, y, and 0, agree well with those of Table III.

The line a was rarely visible in the spectrum of olefiant gas, and its appear-
ance was only momentary, which confirms the opinion already stated, that it does
not properly belong to the carbohydrogen spectra. ‘To the proof already adduced
in support of this opinion, I may here also add, that 1 have found it permanently
absent in the flames of carbonic oxide, and of light carburetted hydrogen.* The
continued invisibility of so brilliant a line of the spectrum, coupled with its

* T have found that the column of heated air rising from the flame of a spirit lamp with a salted
wick, is most energetic in communicating yellow light to the exterior envelope of the flame of the
Bunsen lamp. This effect is apparently confined to the outer, or oxidizing portion of the flame,
where there is no excess of hydrogen, to decompose the chloride of sodium; and the experiment is

interesting, as tending to prove that the yellow light may be caused by simple incandescence, without
the actual combustion of sodium.

:

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 425

almost instantaneous appearance at very long intervals,—for it did occasionally
appear for a moment,—satisfactorily proved it to be due merely to foreign matter
which had accidentally entered the flame.

From an examination, either of Table IV., or of Plate VIIL., fig. 1, it will be seen
that certain of the lines in the carbohydrogen spectrum occupy nearly the same
places in the scale of refrangibility with dark lines in the solar spectrum. These
are the lines a, y, 6,, and ¢, which coincide more or less exactly with the lines D,
b,, F,, and G. The first of these coincidences has been long known, having been
discovered by FRAUNHOFER ;* and similar remarkable relations have been observed
by Sir Davip Brewster to exist between certain lines in the spectrum produced
by “ deflagrating nitre,” and the corresponding lines of the solar spectrum.t+

From these singular coincidences occurring in so many different cases, the
inference might be drawn, that all bright lines in the spectra of flames coincide
with dark lines in the solar spectrum ; and the extremely close proximity of the
lines y and 0,, 0, and F,, Zand G indicated in Table IV., might at first sight seem
to confirm such an opinion. For it might be argued, that so close agreements in
the ascertained deviations indicate absolute identity; the minute differences
observed being attributed simply to errors in the observations. It will be seen,
however, that the observed deviations of the lines 6, and y, differ by no less a
quantity than 40”, which is quite beyond the sum of the probable limits of error
in the observations for these lines, which I have ascertained to be only about 5’ ;
and thus their coincidence is shown to be highly improbable.

But any remaining doubt on the subject is completely removed, by the simul-
taneous observations of the spectra of sun light and olefiant gas, given in Table V..
where the micrometrical measurement of the interval between the lines } and y
differs only by 11” from that obtained by the theodolite observations. In fact,
the bright line Y was seen when the spectra were viewed simultaneously, to coin-
cide, not with the dark line 0,, but with the clear space immediately beyond it.
If we omit the line a, which, for reasons already fully stated, I do not regard as
properly belonging to the carbohydrogen spectrum, not one of the other twelve
lines which I have observed in that spectrum occurs near any conspicuous dark
line of the solar spectrum, with the exception of the lines yy, 6, and %, which fall
near 6,, F, and G. Now, of these, y has been proved beyond doubt, not to coin-
cide with b,, but with a bright space in its vicinity ; and from the simultaneous
observation of the spectra of sun light and of olefiant gas, as well as from the
results of the theodolite observations, I believe that the other bright lines of the
carbohydrogen spectrum also coincide not with dark lines, but with bright spaces
| in the solar spectrum.

* Scuumacuer’s Astronomische Abhandlungen, 1823, p. 29. See also Brewster’s Edinburgh
Journal of Science, vol. viii., p.'7. M. Foucaurr has lately verified this result with the double
yellow line seen in the spectrum of the voltaic arc, between charcoal electrodes. See Dz La Rive’s
Electricity, vol. ii1., p. 322.

+ Report of British Association, 1842, p. 15.

426 MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

From the fact just stated, that most of the lines in the carbohydrogen spectrum
occupy positions where, in the solar spectrum, no conspicuous dark lines occur,
direct comparison of the spectra, by simultaneous observation, seems almost
impossible; for, before the fainter lines of the carbohydrogen spectrum become
visible, the solar spectrum must be rendered so faint, that its finer lines have
disappeared. On the other hand, to make a complete comparison of the spectra by
actually measuring with the theodolite, the positions of the finest lines of the solar
spectrum, would be a most formidable task. For when we consider that Fravun-
HOFER has represented on his map of the solar spectrum, 350 lines, while Sir
Davip Brewster, by the aid of very excellent optical means, has observed the
spectrum to be “divided into more than 2000 visible and easily recognized por-
tions, separated from each other by lines more or less marked,’’* it follows, allow-
ing 5° for the angular dispersion of the extreme rays of the spectrum,—that the
average interval between the lines observed by him is only 9’. Extremely de-
licate theodolite measurements would therefore be required, in order to determine,
whether or not any bright line of a flame spectrum was or was not coincident
with one or other of the numerous small lines of the solar spectrum ; and even
where a coincidence was ascertained, it might be fairly attributed to chance, just
as a binary star may be only optically, and not necessarily physically double.

In cases, however, where there is a remarkable analogous configuration of
two groups of lines, accompanied by exact coincidence, as between the double lines
a and D; and more especially where we actually view the striking phenomenon
of the lines in the spectra optically superimposed, the impression of some phy-
sical connection between the two groups becomes irresistible.

The coincidence of y, the most brilliant line of the carbohydrogen spectrum,
with the clear space immediately beyond 0,,—the most refracted line of a group,
which, whether we regard the singular configuration or the strength of the lines
which compose it, is perhaps the most notable in the solar spectrum,—is a phe-
nomenon which seems deserving of attention as probably indicating also some —
physical relation.

In conclusion, I may observe, that from the facility with which, by means of
the Bunsen lamp, the carbohydrogen spectrum may be obtained, and from the
definite and readily identifiable character of the lines which compose it, these
lines may be useful in optical researches, where, from any cause, sun light can-
not be employed. It will be seen, from Table IV., that, for most practical purposes,
the lines a, y, 6;, and ¢, may be assumed as identical with D, b,, F,, and G of the
solar spectrum; any error in the index of refraction calculated on that assump-
tion, affecting only the fourth or fifth place of decimals.—7th June.

* Edinburgh Trans., vol. xii., p. 528.

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN. 427

TaBxeE I, Observations of the Angle of the Prism.

SEeriEs I. SERizEs II.

Total Number Mean of all the
of Observations. Observations.

Number of | Mean of the Obser- Number of Mean of the Obsere
Observations. vations. Observations. vations.

—

5) G0ra) 0" 1b” 3 G07 OF 187 8 GOR “OG?

TaBiE II. Observations of the Solar Spectrum.

COLLECTED OBSERVATIONS

camel ana a oF Minimum DEvrarions.
Tigra o> || ===F a aS Difference
Spectrum. | Number of Namahenar of Means Total WV
Sala al cies Th, cen Vii! |e eS
Observa- og Observa- ee ber of Ob- eae Be 2 Pte
tions. é tions. servations. BIN GUOTE,

At t20F SOMA Or.) 6”

A Bee Ar 420. 27718 3 6 | 47° 20° 24”
a 2 | 47 29 54 Ama \SQ anno! | 8 6 |47 29 59
B 2 | 47 39 52 SUN ay 29re oma ON 1 5 |47 39 51
Cc 2 |47 50 22 Bhi ag 150" TOMO 5 [47 50 12
CF Lo ufid8 cOnrad 1 | 48 10 50
D 2 48 be) 15 we | 48 Lear t2yl0- 3 6 |48 18 13
E 2. | 40 50 24 4) | 48 on) 26 0 2 6 | 48 55 25
bt A | AQvatidr ade 5 149. 1 44/0 1 9 | 49 45
b, Zo 1.49 37 I) s\ 49) | orsaos toners By 49 onaG
b, 2 |.40 55 So) 40) QuroGe Cues dl 5 | 49 2 55
F Ber 40) 29.18 3 |.49 29019 0. 10 5 |49 99 15
F,* Ae) Ag: 40.12 4 | 49 49

G 2. a0 sbE 2 8. EO SR MEN 5 _|.50.35

H ie bbe a4 50 Beehial 34049 7 | Sw vga 44

. . Mean Temp. of Prism, 64:2 F.
Se ay en: Bas _ Mean Tout of Air, . 62°5
; Mean Barom. . . . 29:98
0s eee ee ae a ee, eee See eS,

* ©, and F, are used here to denote very strong lines adjacent to FRAUNHOFER’S lines, C and F.

{| FRAUNHOFER denotes by 6 the two most refracted lines of a remarkable group, represented by three strong lines
in his map of the solar spectrum. I have here denoted these lines by b, b,, b,, in the order of their refrangibility.
On 20th May, about 74 10™ p.m., when the sun was rather low in the horizon, but free from clouds, I observed
with a power of 21, the line 6, to be very finely but distinctly double, so that the group consists of four lines.

VOL. XXI. PART III. 5 7,

428

MR WILLIAM SWAN ON THE PRISMATIC SPECTRA OF THE

Tasre III. Observations of the Carbohydrogen Spectrum.

—— CTT

SERIEs I. Serizs II,
5 Difference
Spectrum, umber of | yjgn | Namberof| aay | me
tions. I. tions. II.
a 5 46° Te 147 2 45° ere tery. & “Ae
B 3 48 32 9 6 48.32 7-10 ~2
8, 9 48 35 12
ee 9 48 87 50
Cs ane 9 48 40 10
Y 9 #0. 118. 135 4 49 SLily Or @
%, ae i 9 49 23
r) 2 49 41 58 6 49.0410 bei 00
é, 9 49 44 48
0, 9 |49 46 37
0; 9 |49 48 41
€ a * 4 50 27 54
¢ 3 50 35 37 6 50 35 28| 0 9

COLLECTED OBSERVATIONS
OF MINIMUM DEVIATIONS.

Total Num-
ber of Ob | Mean of athe
a 48° 18’ 14”
9 48 32 7
9 48 35 12
9 48 37 50
9 |48 40 10
13), | 49.eegeme4
8 49 41 58
9 49 44 8
9 |. 49° 3468 527
9 49 48 41
4 50 27 54
9 50 35 33

a | ee

Mean Temp. of Prism
Mean Barom.,

A aa an Mean Temp. of Air,

Mean Barom.

60:4
29-56

Mean Temp. of Prism. 626 FE’

In Table III., the deviations of the lines «, 6, y, 3, and Z, were alone determined by the theodolite; the other lines
were then referred to «, 8, &c., by micrometer observations.

Taste IV. Comparison of Contiguous Lines in the Solar and Carbohydrogen Spectra.

SoLtar SPECTRUM.

3 Deviation

& (D.)

pS

Dit se Sa38
b| 49 2 55
Fj 49 49 2
G| 50 35 4

Index of
Refraction (.)

1621079
1:628659
1636407

1:644068

3
&
4

a

CARBOHYDROGEN

Deviation

(D.)

48° 18’ 14”
49 3 34
49 48 41
50 35 28

SPECTRUM.

Index of
Refraction (.)

1°621083
1628769

1636349

1644147

De—D,

D,— Dz,

D,, — Ds,

Dz—D,

0’ 1”| f.—p |0-000004

0 39 | py— ps, [0°000110}

0 21 |p, —ps, |0-000058}

0 24 | uz—p, |0:000079

i

FLAMES OF COMPOUNDS OF CARBON AND HYDROGEN.

Taste V. Observations on the Spectrum of Olefiant Gas.

Minimum Deviations for Lines Intervals between bLines in the Solar Mini
in Solar Spectrum, from and Gas Spectra, measured by D Ne
Table IT. the Micrometer. eviations.

servations.
48° 18 13” 48° 32’
48 365
48 38
48
49
49
49
49

429

| bd
agnink 1,
seugrlded A bay 5 dant lll

pa
: — i ‘

>.)

@aaTs)

XKXX.—On the Laws of Structure of the more Disturbed Zones of the Earth's Crust.
By Professor H. D. Rogers.

(Read 21st April 1856.)

Having, several years ago, in the course of a prolonged investigation of the
geological structure of the Appalachian chain of the United States, conducted
partly in co-operation with my brother, Professor W. B. Rocerrs, as a purely
scientific inquiry, partly by myself, in connection with a Government Survey of
the State of Pennsylvania, discovered what we deemed important laws, applicable
generally to all corrugated tracts of strata; and being prepared, by observations
since made in the United States and in Europe, to extend their application, and
give them a more general expression, I have thought that 1 could not select a
more suitable subject for my first communication to the Royal Society of Edin-
burgh, than this portion of descriptive and dynamic geology, which has engaged
much of my attention, theoretically and practically, for these many years. In
presenting an outline of the views already arrived at, and published by us as a
necessary part of the further generalizations since reached, I will refrain from re-
peating, in historical detail, what we have already written, but will give our con-
clusions in the form and with the brevity most compatible with clearness, refer-
ring to the printed papers and communications where the special topics included
in this more general summary may be seen.

Wave-like form of all Upraised Tracts of the Crust.

The first or most general fact which I would enunciate respecting any portion
of the earth’s crust that has suffered elevation or depression from the position or
level in which its strata were originally deposited, is, that the displaced beds
present invariably the form of one or many waves, even when within limited
geographical areas they may seem to retain an approximate horizontality. This
comprehensive statement respecting the wave-like structure of the earth’s crust,
is not invalidated by the instances of disordered dip seen in certain dislocated
regions, such as some of the coal-fields of Great Britain; for it will generally be
found that the breaks or faults in the strata only separate disarranged portions
of what were originally continuous undulations.

In all large stratified areas, where the dip is both gentle and persistent
in its direction throughout considerable spaces, and where this dip is genuine,
the result, that is to say, of a true displacement of the mass, and not a conse-
quence of the original obliquity of deposition called false bedding, the crust
waves will be found to be of an amplitude proportioned to their flatness; but in

VOL. XXI. PART III. 6A

432 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

those districts where the prevailing inclinations are steep, and where they are
directed to opposite points, it will be found invariably that the inclined masses
are but the parts of successive arches, or rather waves, the denuded or broken
crests of which approach each other the closer as the dips are steeper.

Parallelism of the Crust Undulations.

It is, therefore, another general fact regarding disturbed zones of the crust,
that where the displacement from horizontality has been great, the strata are
arranged in longitudinal tracts, or great belts of parallel waves. These, where their
symmetry of structure is not marred by dislocations of the crust, or hid by over-
lapping superficial deposits, exhibit a remarkable and beautiful resemblance
to those great and continuous billows which are called by seamen rollers, and by
mechanicians saves of translation. Far more continuous in their crests, more
strictly parallel, and more symmetrical in form than the wind-produced waves
upon the waters of the globe, such great swells or rolling billows, engendered by
wholly different forces, are, I conceive, the true archetypes of the undulations
visible in the more corrugated portions of the earth’s crust. Perhaps in no
uplifted district of the surface are these crust-waves so symmetrically deve-
loped, or so readily recognised, as in the Appalachian Mountains of the United_
States. It was there that WitL1AM B. Rocers and myself, analyzing their forms,
and tracing and connecting their axes, detected those phenomena of shape and
gradation which led us to the general laws of crust flexures which we have ven-
tured to publish.

But we believe that all mountain zones, and all corrugated districts gene-
rally, which have been elevated, like the Appalachians, at one epoch, and by
crust movements observing only one prevailing direction, will be found to pos-
sess this wave-like structure, under similar conditions of gradation, and in a like
conspicuous manner. It is only those tracts which have been revisited several
times by the elevating and undulating forces, and especially those where the
successive disturbances have not coincided in direction, but have crossed each
other, causing interference and intersection of the waves, as in what is called
a chopped sea,—such districts, for example, as the Swiss Alps and the mountains
of Cumberland and Wales,—that we fail readily to discern the wave structure of
the strata, or, perceiving it in part, are unable, without extreme toil and patience,
to connect the originally related outcrops of the rocks, and reconstruct in our
minds, and represent to the eye, the undulations that actually exist in a broken
and disguised condition.

Wherever we have been led, either from observations in the field, or from a
careful perusal of the descriptions of geologists, to a clear recognition of the dip-

structure of any corrugated zone, whether mountain chain or otherwise, not con-

fused by different systems of elevatory movements of the crust, we have become

:

‘

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 433

impressed with its marked resemblance in all the essential features of the un-
dulations, both as respects the typical forms of the individual waves, and the
grouping and gradation of the several sets of waves, to the flexures character-
istic of the Appalachian chain of America. I was particularly convinced of
this resemblance upon examining, in the summer of 1848, the structure of
the Jura chain of Switzerland ;* and scarcely less struck with the agreement I
noticed between the phenomena on the borders of the Alps, especially in the
Bernese Oberland, and the features which distinguish the most corrugated
tracts at the south-eastern base of the chain of the Appalachians.

RELATIONS OF FLEXURES TO EACH OTHER.

If we regard now the flexures which constitute any great undulated or cor-
rugated belt of strata, we shall find that these display the following laws or ge-
neral facts of relationship :—

Parallelism.

1. When seen in their simplicity, or undisguised by cross breaks and undula-
tions, those of a particular district show a remarkable degree of mutual parallel-
ism. Not only are they parallel to each other, but to the general trend of
the portion of the mountain system to which they belong, and especially to its
chief igneous axes, where it possesses such.

2. The flexures or waves, where the undulated zones are wide and complex,
occur in groups or lesser belts ; those constituting such subordinate series ob-
serving the law of parallelism still more strictly than group does towards group.
This remarkable parallelism of the adjacent flexures in an undulated region be-
longs not only to those waves and groups of waves which are rectilinear in their
crests, but to such as curve even very considerably in their lineation. Nowhere,
perhaps, is the constancy of this law so well displayed as in the Appalachians.
This great mountain zone of the United States and Canada, about 1500 miles in
length, and more than 150 in its maximum breadth, consists longitudinally of eleven
different sections, six of which are straight, three curvilinear, and convex towards
the north-west, and two also curvilinear, but convex towards the south-east.
Three of the straight sections have an approximately east and west trend, and the
other three an approximately north and south course. Notwithstanding the great

windings in the direction of the chain thus indicated, it is remarkable that each
division or segment of it, whether straight or curved, is made up of crust-waves
and groups of waves, which are essentially in mutual parallelism; and wherever
a seeming exception to this rule presents itself, as on the Upper Juniata in Penn-

; * See Abstract of Communication to American Association for Advancement of Science, Cam-
bridge, Mass., March 1849, p. 113.

434 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

sylvania, and in Northern Vermont, it will be found to arise from the interference
or interlocking of the ends of the waves of different but adjacent segments.

3. Crossing any great belt of anticlinal and synclinal flexures, such as that of
the Appalachians, or that of Belgium and the Rhenish Provinces, it will be no-
ticed, when the undulations are carefully traced and compared, that these consist
of more than one class as respects dimensions; indeed they will be found to be
of two or three grades, when grouped according to their length, height, and am-
plitude. In most parts of the Appalachian chain, there are at least two prevail-
ing magnitudes in the waves. The chief class, or primary undulations, are of
great size, their length amounting to from 50 to 120 miles, and their breadth to
several miles, except where they are closely compressed. The subordinate or
secondary waves are seldom more than a fourth of a mile wide, nor do they
usually exceed ten miles in length, and in many groups they are much shorter.
Frequently a third class is to be met with, of still smaller and less persistent
flexures,—rolls of the strata, as they are called in the coal-mining districts of
Pennsylvania,—which seem to be only local corrugations of the more superficial
rocks, and not true undulations of the crust pervading the entire thickness of
the formations. The relations of the primary to the secondary waves will be
enlarged upon hereafter. It will suffice, under the present head of parallelism of
flexures, to state that, for the Appalachians at least, those of the second order
are not necessarily parallel to those of the first, though within a given district
they observe among themselves the same mutual parallelism which the larger
or primary waves exhibit.

FORMS OF THE WAVES.
Symmetrical Flexures.

The individual waves or flexures of a belt of undulated strata occur under
three essential varieties of form. The first, or most simple, is that of a convex
or concave wave, or in technical geological language, an anticlinal or synclinal
flexure, in which the two slopes of the wave are equal in their degree of incur-
vation or steepness. This symmetrical form is restricted chiefly to the gentler
or flatter undulations, and especially to those of considerable amplitude. We do
occasionally meet with steep waves of the strata, having a nearly equal inclina-
tion on both their sides; but these are generally broken curves, exhibiting a snap
or sudden angle at the anticlinal or synclinal axis, in place of the gradual arch-
ing, which is the normal form of all regular crust undulations.

Normal Flecures.

Another and more prevailing form displays a more rapid incurvation, or steep-
ening of the flexure, on one side than on the other. Waves of this type have

been called Normal Flexures by my brother and myself, in our descriptions

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 435

of the Appalachian chain, where they are very common. They are to be seen
abundantly in the Jura, and in the exterior hills of the Alps. They abound, too,
in the undulated palzeozoic region of Southern Belgium, and are a marked fea-
ture in the coal-basins of that country.*

These flexures prevail wherever the forces that disturbed the crust were neither
excessively intense nor very feeble. They usually hold an intermedjate position
geographically, answering to the middle place they occupy as respects energy of
undulation between the groups of flat symmetrical waves, and those which are
closely folded, to the description of which I next proceed. Almost invariably,
those of a simply undulated tract, exhibit their steeper slopes directed all to one
quarter.

Folded Flexures.

This third and remaining class consists of flexures in which there is an inver-
sion or doubling under of the steeper side of each convex curve or wave. When
this structure is at a maximum, the folding back, downwards, of each convex
or anticlinal arch amounts almost to a parallelism of the two branches or sides of
these curves; and where there are several such foldings, alternately convex and
concave, the strata may be said to be crimped or plicated into one dip, though
the entire change of inclination through which the inverted portions have
been bent, amounts to the supplement of the angle of the dip or the difference be-
tween the apparent dip and 180°. It is a necessary feature of all such folded
flexures, that the approximately parallel sides of the folds dip obliquely and not
perpendicularly to the horizon. They are, therefore, but exaggerated instances
of the class of normal fiexures, or those where one branch of the curve is steeper
than the opposite. As in the case of the normal flexures, the more incurved sides
of these folded waves all look the same way.

Axis Planes.

It is convenient, for the purpose of expressing the kind of flexure, its degree,
and its direction, to make reference to the geometric planes which bisect or equally
divide the anticlinal and synclinal bends. These imaginary planes we have called
the axis planes of the undulations, being those which include all the horizontal
lines or axes round which the individual concentric strata have bent in the act of
undulating or folding. In the first-described class of flexures, or those of symme-
trical curvature, each anticlinal and synclinal axis plane is necessarily perpendi-
cular to the horizon. In the second class, or the normal flexures, these axis planes
are necessarily not perpendicular, but steeply inclined to the horizon, and their
deviation from the perpendicular is in proportion to the difference of inclination,

* See Dumonv’s Memoir sur les Terrains Ardennais et Rhenan, &c.
VOL. XXI; PART III. 6B

436 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

or of incurvation of the two slopes of the wave, modified, according to a certain
law of variation, with the dip. In the third class, or that of flexures with zvzer-
sion, the axis planes are likewise not perpendicular ; and it will be found that,
in the great majority of instances, they dip with a less degree of steepness than
the planes bisecting waves of the normal or other unsymmetrical type. Indeed, it
may be stated generally, that, just in proportion as the flexure departs from the
symmetrical wave form, through greater and greater inequality of dip, up to paral-
lelism of the inverted with the uninverted branch of the curve, the axis plane
departs from the perpendicular direction, to assume a less and less inclination to
the horizon. In many districts of extreme plication of the strata, for instance in
the Atlantic slope of the middle and southern States of North America, also in
the Bernese Oberland, in the Ardennes, and in North Wales, the axis planes dip
at an extremely low angle, consequent on the excessive amount of horizontal
movement which the strata have undergone in the act of folding.

So nearly parallel are the inverted to the uninverted sides of the folds,—the
axis planes all, of course, dipping one way,—in many districts of close plication,
that the detection of the anticlinal and synclinal bends is not a little difficult,
especially where the sections, natural or artificial, are not perfectly clear of
superficial debris. In such cases the whole plicated mass looks as if it contained
but one dip, or consisted of only one thick sequence of deposits, instead of am uch
thinner formation many times reduplicated. To add to the liability of error, such
bodies of folded strata are especially subject to that condition of jointage which is
called slaty cleavage. In this structure, as I shall presently show, the divisional
planes not only tend to obscure the original planes of sedimentation by their
greater conspicuousness, but they often, by observing a very prevailing parallel-
ism to the general dip of the folded beds, or, more strictly, to their axis planes,
effectually disguise the anticlinal and synclinal curves. It is from these circum-
stances, and not from any erroneously supposed effect of truncation or denuda-
tion, actually to remove the anticlinal bends of the strata, that it is frequently
so difficult to detect the true order of original superposition and the real thick-
ness of closely plicated formations. Of course, no erosion upon an anticlinal
axis, however closely folded it may be, can obliterate the bends in those beds
which have their curves below the level reached by the denuding agent.

Crust Waves Straight and Curvilinear.

Regarding the great flexures of the crust as individual waves, which in truth
they seem to be, we find them exhibiting, not only the above differences in the
sloping of their two sides, but marked differences of form when viewed longitu-
dinally. Thus, many are of extraordinary straightness ; some of the larger simple
anticlinals of the Appalachians being more than 100 miles in length, without any
material or even perceptible horizontal crooking or deviation in their crest lines.

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 437

Others again are curved, some of these sweeping convexly towards the quarter
of chief crust dislocation and metamorphism, others curving convexly from it,
but we never find these two classes associated in the same group, and in the
Appalachians, never even in the same segment of the undulated zone. In some
districts of this and other chains, some of the principal curvilinear anticli-
nals and troughs are quite as extended in length as the great axes which are
straight. They appear to be independent waves generated from curvilinear frac-
tures of the crust, and not to be merely the bending terminations of adjacent
rectilinear flexures. One of the most interesting features belonging to some of
them is, their extent of curvature, and the graceful continuous smooth sweep which
their curving axes present, often without jog or hitch, from one extremity to the
other. This crescent-like form is developed in a high degree in those curving
sections of the Appalachian chain, where the waves are convex north-westward,
-or from the quarter of maximum dislocation—the Atlantic slope. In the Juniata
division of the chain in Pennsylvania, some of the curving anticlinals, 80 and
100 miles in length, change their trend between their two extremities as much
as 40°; and in the Delaware division of the same chain, which also bends with
a concave sweep to the north-west, the deflection in more than one great syn-
clinal trough, and anticlinal axis, is not less than 60°. This fact of the curvi-
linear form of anticlinals and synclinals of great length in this was long ago
offered by us, as a phenomenon incompatible with the generalization of the
eminent French geologist M. Ex1e pr BEAuMontT, who conceives that the lines
of elevation of the crust have been great circles of the sphere, and that those
of a given geological epoch have invariably observed one constant direction.
The whole of the Appalachian chain having been demonstrably corrugated into
its present undulations at one epoch, that of the end of the coal period, the simple
fact that its different groups of waves deviate as widely in direction from each other
as 60°, while those of each group are reciprocally parallel,—the whole chain in-
deed, if subdivided on this principle of direction, including not less than eleven
conspicuous segments,—is itself enough to show that no particular constancy of
relation can be established between the dates of elevations, and the mere direc-
tions of the lines or axes of the strata. But this other fact of so marked ach ange
of direction in one and the same axis, as displayed by these crescent-shaped waves,
is, if possible, in still more striking contradiction with that hypothesis. Another
fact connected with the groups of curving waves in the Appalachian chain is par-
ticularly deserving of mention in this place, from the bearing it appears to have
upon the question of the direction of the pulsatory or wave-like motion of the crust,
at the time of the permanent production of the flexures. It is this—the individual
waves in all the segments of the chain which are convex north-westward exhibit,
as already said, a continuous symmetrical crescent-like curvature ; those, on the
contrary, which are included in the other curvilinear districts, convex to the south-

438 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

east, or towards the region of dislocation and metamorphism, present a much
less regular incurvation along their anticlinals and synclinals, and a far greater
amount of interference and of dislocation. These appear indeed to be the sec-
tions of the chain, where the greatest amount of tangential wrenching, rupturing,
and warping of the crust has taken place, and where the greatest amount of
transverse hitching and fracturing has happened to all the strata. The causes of
this difference will, I think, be seen, when I shall have developed our theory of
the mechanical forces which undulated the Appalachian strata, and set in mo-
tion the stupendous billows of the crust, which resulted in the elevation of
these mountains. An inspection of the best maps and sections of the more dis-
turbed European zones, leads me to believe, that a similar contrast prevails be-
tween the curvilinear waves which are convex to the districts of disruption,
whence I suppose them to have proceeded, and those which are concave to the
same quarters; but before this law in all its generality can be established, geolo-
gists must institute far more critical researches into the physical structure of those
undulated and plicated districts than they have hitherto conducted.

GRADATIONS IN FLEXURES.

Succession from the Folded to the Symmetrical Waves.

Several phenomena of gradation will be found to display themselves when we
cross any broad belt of plicated and undulated strata. Starting from the side of
maximum disturbance and contortion, invariably the quarter of maximum igneous
action,—displayed either in Plutonic eruptions through the crust, in crust disloca-
tions, or in metamorphism of the sedimentary rocks,—the flexures first met with
are of the obliquely plicated form. Advancing towards the middle of the zone,
the folds become obviously less close, and proceeding still farther, they gradually
open out, displaying more conspicuously their anticlinal and synclinal curves,
until the inverted side of each wave becomes only perpendicular. This perpen-
dicular altitude of the steep side soon becomes a dip towards the opposite quarter
from that previously observed by both sides, and as we proceed, the steepness of
the slope of the wave now rectified in position, grows progressively less and
less, until on the far side of the zone, both slopes approximate to equality.

Expansion of the Waves as they pass from the Folded to the Symmetrical Form.

Concurrently with this gradation, there is a progressive opening out of the
spaces between the crests of the successive waves, such indeed as to amount in
the Appalachians, and sundry other broad regions of crust-undulation, to an en-
largement by many times of the amplitude of the more compressed class of —
flexures.

OF THE MORE DISTURBED ZONES OF THE EARTH'S CRUST. 439

Progressive Flattening down of the Flexures.

A third feature of gradation shows itself in the progressive sinking or flatten-
ing down of the successive individual flexures, until these finally pass into hori-
zontality. These three types of form in the waves, as respects their expansion,
their increase of relative distance or amplitude, and their declining height, are
conspicuously discernible, wherever we cross the great Appalachian chain of the
United States, by any section, in a direction from south-east to north-west. An
inspection of the engraved sections illustrating our paper on the physical structure
of the Appalachians,* or an examination of the more numerous similar diagrams
explanatory of the geological surveys of New Jersey, Pennsylvania, and Virginia,
will amply avouch for the correctness of this generalization. It is further borne
out in the published reports of the Government Survey of Canada, where the pli-
cated structure of the green mountain range of Lower Canada, along all its south-
eastern border, and the universality of the south-eastward dip of the folded strata,
—in other words, of the dip of the axis planes,—is very distinctly set forth by Sir
Wii1iam Logan.

Not only does the entire chain in its breadth exhibit a general gradation in the
several features here described, but each of its great component groups of flexures,
presents the same progressive opening, recession, and flattening down of its waves
in the same uniform north-west direction.

Similar phenomena of gradation will, we feel assured, disclose themselves in
any section made from the Taurus range, north-westward through the Rhenish
Provinces and Belgium, where, on the one side, the more ancient and much meta-
morphosed strata at the base of the Paleozoic system, according to the observa-
tions of Murcuison and SepGwick, present much reversal of the dip, and where
one and the same dip, namely, to the south-south-east, is continued with very few
exceptions across a belt of 50 miles; whereas, on the opposite or northern side
of the zone, as is well shown in the beautiful sections of M. Dumont, the flexures
of the Belgian coal-fields are of the normal type, and much more open and
dilated.

Nowhere perhaps in Europe are these gradations in the undulations of strata
more beautifully exposed than on the flanks of the Alps. Deep in, towards its
higher central igneous chains, the plication of its stratified rocks is excessive, and
the inclination of the axis planes remarkably low; but advancing outwards, the
waves gradually lift their crests, throw forward their inverted sides, and assume
that type of flexure which we have called the normal one; while, at the outward
base of the mountains just before these undulations are concealed by the over-
lapping tertiaries of the plains of Switzerland, and of Northern Italy respectively,

* Transactions of the Association of American Geologists.
VOL. XXI. PART III. 6c

440 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

the curves become, in many instances, broad, depressed, and al-
most symmetrical in form.

From the descriptions here given of the structure of the
Appalachian chain and other disturbed districts, it is obviously
a general law, that the axis planes of the flexures are not only
inclined all in one prevailing direction, though at different angles,
but that they dip invariably towards the quarter or zone of maxi-
mum disturbance and rupture of the crust.

FRACTURES OR FAULTS IN TRACTS OF UNDULATED STRATA.

Two classes of dislocations abound in all zones of plicated and
undulated strata, where the crust waves exhibit much steepness,
and especially where they have the inverted or folded form. By
far the most numerous, though the shortest and least conspicuous
class, are the breaks or faults which run approximately trans-
verse to the strike of the anticlinal and synclinal axes. These
may be extensively recognized in the Appalachians, where they
are a primary cause of the deep ravines, or breaches through the
ridges, which furnish passage to nearly all the rivers, and even
lesser streams which drain this chain. Such ravines are especially
frequent near the extremities of the large anticlinal waves, par-
ticularly where they have been cut through along their crests
by denuding waters, and have given rise to valleys of elevation
and erosion, inclosed by monoclinal, outward-dipping, sandstone
ridges. It would seem as if the elliptical folding round of the
strata towards the ends of the great denuded waves had caused
the horizontal wrenching which resulted in these fractures. Mr
Witi1am Hopkins, of Cambridge, has, in an able paper on the
subject of dislocations affecting dome-shaped elevations of the
earth’s crust, indicated the true source, I conceive, of the double
system of fractures to be met with in all elliptical anticlinal belts.
An elongated anticlinal wave is, in truth, only a greatly lengthened
elliptical dome, in which the radial cracks caused by a maximum
tension in the strata transmitted from the more central portion
of the crust-wave, are distributed, some of them longitudinally,
others transversely, as respects the anticlinal axis, the transverse
ones multiplying themselves where the elliptical strain has been
greatest, towards the two extremities of the waves.

The other far more conspicuous class of dislocations connected
with these crust undulations, are the great longitudinal ones.
These are of frequent occurrence in the more contorted portions of the Appell

Generalized Section of the Appalachian Chain from north-west to south-east, through the Juniata district of Pennsylvania.

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 441

chian zone, especially in those where the chain is convex to the south-east, and in
the straight sections of South-western Virginia and Eastern Tennessee. But I
am persuaded, from the descriptions of geologists, and from my own observations
that the fractures of this class are equally numerous in the Jura Mountains, in
the Alps, in the district of the Ardennes, in Belgium, and in the mountain chains
of Scotland. A leading feature of these great fractures is their parallelism to the
main anticlinal axes, or lines of folding of the chains to which they belong. They
are, in fact, only flexures of the more compressed type, which have snapped and
given way in the act of curving, or during the pulsation of the crust. They
coincide, in the great majority of instances, neither with the anticlinal nor the
synclinal axis planes of the waves or folds, but with the steep or inverted sides of
the flexures, and almost never occur on their gentler slopes. This curious and in-
structive fact may be well seen in the Appalachians of Pennsylvania and Virginia,
by tracing longitudinally any one of their great faults from its origin on the steep
flank of an anticlinal wave aldng the base of its broken crest to where the anti-
clinal form is resumed again. The following brief description, from our memoir
on the Physical Structure of the Appalachians, taken from the Transactions of
the American Association, will show the general phases through which these
fractures pass :—

“ From a rapidly steepening north-west dip, the north-western branch of the
arch (or flank of the wave) passes through the vertical position to an inverted or
south-eastern dip, and at this stage of the folding the fault generally commences.

“ It begins with the disappearance of one of the groups of softer strata lying
immediately to the north-west of the more massive beds, which form the irre-
gular summit of the anticlinal belt or ridge. The dislocation increases as we fol-
low it longitudinally, group after group of these overlying rocks disappearing from
the surface, until, in many of the more prolonged faults, the lower limestone forma-
tion (Cambrian or Lower Silurian) is brought for a great distance, with a moderate
south-easterly dip, directly upon the Carboniferous formations. In these stupen-
dous fractures, of which several instances occur in South-western Virginia, the
thickness of the strata ingulfed cannot be less, in some cases, than 7000 or 8000
feet.”

One of these enormous faults in South-western Virginia has a length of
more than 80 miles, and is almost perfectly straight. It follows the south-eastern
slope of Brushy Mountain, from the head of Catawba Creek to the vicinity of the
court-house of Smyth county, engulfing all the strata of the south-eastern half of
a synclinal basin, of which the Brushy Mountain remains as the other half.
’ Where the dislocation attains its maximum intensity, or shows the greatest dis-
placement of the strata, the lower formation,—the Auroral Appalachian limestone,
the equivalent of the Festiniog group of England,—of one side of the fissure,
rests in an inverted attitude, with a gentle south-east dip, directly on the south-east

442 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

dipping Vespertine grits and shales—represented in Great Britain by the lowest
Carboniferous strata,—forming the other wall of the fault.

General Parallelism of the Faults to the Axis Planes.

It is a very general feature of the great longitudinal faults, whether these
coincide with the anticlinal and synclinal axis planes, or occur, as they more fre-
quently do, on the steep sides of the flexures, to dip in the same direction with
the axis planes. In the Appalachian chain their inclination, therefore, is almost
invariably towards the south-east. A consideration of the nature of the forces
which have folded and ruptured the strata, shows that such a direction of
their dip is an almost inevitable consequence of the undulatory movement. It
is only in districts of low symmetrical crust undulations, or those where the strata
are absolutely flat, that the great fractures descend perpendicularly.

In corrugated zones, like those of the Appalachians, the Alps, and the
Ardennes, the magnitude of these main longitudinal fractures, both as respects
length and vertical displacement of the dislocated strata, is in proportion to the
sharp bending or close folding of the waves to which they belong. Thus they
invariably possess their grandest dimensions, in the south-eastern or most pli-
cated belt of the Appalachians, or on that side of the zone where the crust move-
ments have been most energetic.

Uninverted side of Wave usually shoved over the Inverted.

This obliquity or dip towards the quarter whence the movement has proceed-
ed, is evidently the cause of that overlapping of the newer, less-lifted side of the
wave in which the fault lies, upon the steeper, more perpendicular, or inverted
flank ; for the forward or horizontal thrust which accompanied the propagated
wave-movement resulting in the fracture, has, when this once occurred, found
an inclined plane, up which the uninverted slope of the wave slid over the
edges of the strata composing the inverted side. In many instances, as the
Appalachian sections will prove, one flank of the wave has been shoved forward
and upward, unconformably, upon the crushed and buried flank to an enormous
distance. Subsequent erosion having cut down the higher strata of the updriven,
gently-sloping side of the wave, its lower beds are exposed to view, in immediate
contact with the unremoved upper strata of the other side. Where the lower

formations, cut into by the water on both sides of the fault, have been equally —

easy of excavation, especially when they are all of identical composition, as in the

case of the great lower Appalachian limestones, the denuding waters have so ef- ,

fectually planed down the great inequalities of surface at first caused by the dis-
location, as sometimes to have left in the landscape almost no external traces of
the gigantic rupture which lies beneath the soil. It is, then, only by a recogni-

tion of the ages of the respective strata, thus abruptly placed in contact, and —

— ——

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 443

usually, though not always, by some sudden difference of dip, that we are en-
abled to detect the presence and the magnitude of the dislocation.

It seems also necessary, on this occasion, to explain the effects of those great
longitudinal obliquely-dipping faults, when they occur directly in the anticlinal and
synclinal axis planes, which are their occasional positions. The same forward
upward-sliding, just described as having occurred where the fracture is between
the anticlinal and synclinal curves, must have taken place where it has coincided
with these, and as the movement must necessarily have been in the same direc-
tion, lifting, that is to say, the lower strata cut by the fault, upon the edges of
higher and higher beds, in the forward propulsion of the Fig. 2.
flat side of the broken wave, we have no difficulty in un-
derstanding how fractures in these positions, as well as
in the other already spoken of, must have given rise to
that very common phenomenon of the dipping of newer
formations under older ones in plicated and dislocated
countries, like the Alps and Appalachians. This puzzling
feature of stratification, long an enigma to geologists, can,
I conceive, be explained upon no other analysis than that
which is here given, namely, the oblique folding of undu-
lated strata,—the obliquity of the planes of the faults, . oo bee ratat ats
either coincident with, or parallel to, obliquely dipping axis Ee Miah eiidyeing teimlate of free:
planes,—and the forward upward thrust of the uninverted driven forward upon the inverted.
upon the inverted broken strata, through a tremendous tangential force incident to
a wave motion.

EXEMPLIFICATION OF THE LAWS OF FLEXURE, BY THE PHENOMENA OF SOME OF THE
UNDULATED ZONES OF EUROPE.

Belgium and the Rhenish Provinces.—Embracing in one view the undulated
districts of Southern Belgium, the Rhenish Provinces, the Westphalian coal-field,
the Ardennes, the Hundsruck, Taurus, and Hartz ranges, as described and mapped
by M. Dumont and other geologists, we can discern most distinctly all the phe-
nomena of flexure and of dislocation of the strata, here indicated as charac-
teristic of the structure of the Appalachians. We there perceive a wide zone of
crust undulations having its strata most invaded by igneous rocks, and most
ruptured and metamorphosed, along its south-eastern side, and displaying its
most ancient sedimentary formations in a state of close plication, with innu-
merable inversions of the dip, imparting to wide tracts one uniform parallel incli-
nation towards the south-east. Crossing the zone north-westward, we enter
newer and newer strata, until we come to the undulated coal-field of Westphalia
or Belgium, our traverse taking us from the non-fossiliferous formations, at the
very base of the Palzeozoic system. In whatever meridian we make our section,

VOL. XXI. PART III. 6D

444 _. PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

we find the north-west sides of the waves, with few exceptions, steeper than the
south-east ones, not only where they are inverted, but where they have a nor-
mal dip. We find, moreover, as we advance, that the waves grow more and more
open, and that the distances between them increase, that they subside in height,
and that the two slopes approximate nearer to equality. These gradations are
admirably disclosed in any traverse across the strike north-westward, from the
water-shed of the Ardennes to the Belgian coal-fields of the Meuse. I can detect,
in the features of Dumont’s exquisite map of Belgium and the neighbouring
countries, the very same relations of the longitudinal faults to the flexures which
have engendered them, as those above described in the fractures of the Appala-
chians. They evidently occur, for the most part, on the north-west sides of the
anticlinal axes, and cause older strata to ride upon newer ones plunging under them,
with approximately parallel dip. Even the phenomena of cleavage, presently to
be described, will be seen to exhibit the very same laws in the more metamorphie
southern half of this wide zone of plication, which they present along the south-
eastern side of the Appalachian chain, and the Atlantic slope bordering it. This
region of the Rhenish Provinces and Belgium further agrees with the Appalachians,
in being a zone of undulations and plications, where the folding movement has
been all in one direction.

The Jura Chain of Switzerland —tThe Jura chain of Switzerland, as I pointed
out in 1848, in communications to the Geological Society of London, and in 1849
to the American Scientific Association, is another very interesting belt of crust
waves, displaying, in its structure, a close resemblance to the Appalachians.

It embraces, like the American mountains, many groups of waves differing in
the directions of their axes in different districts of the chain, but the individual
groups composed of waves which are remarkably parallel. Few of these undu-
lations exhibit actual inversion of their steeper sides, the dip only in some in-
stances passing the perpendicular, and generally not exceeding on an average 70’,
the gentler or opposite slopes having a mean slant of about 40°. In four traverses
which I made across this chain, I observed one almost invariable law as to the
direction of the steep and gentle sides of the undulations, or, in other words, of
the axis planes. Contrary to first anticipation, and to the belief of many Swiss
geologists, I found the steeper curvature of the waves directed toward the Alps,
and not from them, implying that the crust movement which lifted these grand
and picturesque arches proceeded from the north-west, and not from the chain
of the Alps. This also is a belt whose undulations are chiefly in one direction.

The Alps.—The great chain of the Alps is much more complex in its struc-
ture than either of the undulated zones yet described. It contains but few waves
of the open or normal type, but innumerable close foldings or plications. Through-—

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 445

out a great portion of its length, this lofty and rugged zone of mountains consists
of two approximately parallel chief crests. The great feature in the geological struc-
ture of the whole zone is the presence of belts of closely plicated Mesozoic and Ter-
tiary strata on both flanks of each of these great constituent ranges. But the most
striking, and, at first view, perfectly enigmatical feature, is the inward plunge of
the newer strata beneath the older, in the sides and at the base of both chains.
When, however, the plicated strata are structurally arranged and traced, we find
that this phenomenon assumes the character of a symmetrical folding of the
rocks in two opposite directions from each high central axis. The individual
foldings, with scarce an exception, lean outwards from the central tracts of
the mountains, or from the quarters of igneous disturbance, rupture, and maxi-
mum metamorphism of the crust. In other words, the axis planes of the pli-
cated strata of the flanks of the Alps dip inwards towards the centre of the chain ;
those nearest to it at a low angle, and those more remote at angles steeper and
steeper as the waves recede, expanding to the outer base of the range. High on
the flanks of the Alps, or, what is the same thing, deep in towards the roots of the
mountain, where only the synclinal bends, of the flexed strata, have been protected
from denudation by inward folding, these closely compressed troughs lie pinched
in between the older strata in oblique inward inclination. The transverse sec-
tions expose these bendings, which are called Vs by some of the Swiss geologists.
Here then we behold an exact counterpart in the stratification or structure of a
single flank of the Alps, of that folding with inversion which characterizes the
Appalachian chain, or that of the Ardennes, a single side of the Alps being the
equivalent of the whole of either of those zones ; it consists, that is to say, of a belt
undulated in one direction. Crossing the Alps, or rather one of its component great
chains, we find another simzlar belt of the same strata, plicated in the same way,
with their axis planes dipping also under the crest or orographic axis of the
mountain, but of course, to the opposite quarter of the compass as compared with
the plicated zone of the other flank. This is, I conceive, a true picture of that
feature which, hitherto imperfectly analysed, has been called by some of the geo-
logists of Switzerland, expressively enough,

The Fan-like Structure of the Alps.

Viewed as a single chain, this mountain system consists, then, of two belts
undulating in opposite directions; but, as already stated, it is for the most part of
its length a double chain; and I think each range, especially, where these are
widest apart has a plicated belt of strata upon each of its slopes, so that, for some
districts at least, the fan-like structure is twice repeated; in other words, there

' are four belts of closely folded waves, each having its axis planes dipping to-

wards the base of its own high mountain system.

446 ~ PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

German side. Italian side-

Generalized Section of the Alps, displaying the dipping of the folds of the strata on both sides in towards the
igneous axis.

a, Igneous rocks in central axis of the chain. b, Gneissic and other older strata.
c, Anticlinal flexures. d, Synclinal flexures, or Vs. e, Anticlinal and synclinal axis planes.

A conspicuous and pervading cleavage structure coincident in the direction of
its dip, as I shall presently show, with the oblique axis planes of the folded
rocks, contributes greatly, I conceive, to the illusive phenomenon of an inward
dip of all the strata, or to that general feature which has been called fan-
shaped.*

This inward dip is rendered still more obvious by the circumstance, that the
foliation or crystalline lamination of the more altered strata, itself obeys very
generally a similar law of parallelism to the axis planes of the flexures. Where
this crystalline grain of the rocks does not coincide with the stratification, it
exhibits a great tendency to a coincidence of dip with any system of cleavage
planes belonging to the same or other parts of the mass. In either case, it will
dip inwards towards the igneous axis of the chain, if the strata possessing it are
themselves closely folded in conformity with the prevailing law. But the phe-
nomena of cleavage and foliation will be noticed afterwards. We now proceed to
discuss

GENERAL PHENOMENA OF SLATY CLEAVAGE IN THE APPALACHIANS AND OTHER ZONES OF
PLICATED STRATA.
Cleavage parallel with, but independent of the Dip of the Strata.

It is now a good many years since Professor Sepawick and other geologists an-
nounced the important general fact, that the structure called cleavage pervades the
altered strata affected by it, in directions independent of their bedding or laminz
of deposition. That eminent geologist further announced that these planes are
approximately parallel to each other over large spaces of country, however con-
torted the dip of the rocks. He likewise enunciated a second general law of much
importance, “‘ That when the cleavage is well developed in a thick mass of slate
rock, the strike of the cleavage is nearly coincident with the strike of the beds.”
Subsequently Professor PHities gave to this rule of the cleavage a still more

* From the analysis above given of the structure of the sides of the Alps, it will be seen, that
I entirely concur with Professor James Forsss, and with all the more eminent of the Swiss geo-
logists, in recognizing the fan-like dip of the newer strata, Tertiary and Mesozoic, conformably in
appearance at least under the older strata, metamorphic and gneissic, of the higher more central
tracts, and that I dissent entirely from the theoretical section offered by Mr Danrrt Suarpe-

..

—_ it

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 447

comprehensive and exact expression, when he stated to the British Association in
1843, that the cleavage planes of the slate rocks of North Wales were always pa-
rallel to the main direction of the great anticlinal axes. Other geologists have
abundantly confirmed these generalizations. Since 1837, these phenomena of the
close parallelism of the cleavage planes of a given district with each other, and
with the main axis of elevation of the district, have been constantly observed and
recorded by my brother Professor W. B. Rogers and myself, in our Geological
Surveys of Virginia, Pennsylvania, and New Jersey.*

In 1849, I submitted to the American Association for the Advancement of
Science, at the annual meeting held at Cambridge, Massachusetts, in a commu-
nication on the analogy of the ribbon structure of glaciers to the slaty cleavage
of rocks, a statement of what I had for some years past regarded as the true
law of the direction and position of the cleavage planes of a district of undulated
and plicated strata.

In its simplest expression the rule is, that the cleavage dip is parallel to the
average dip of the anticlinal and synclinal axis planes, or those bisecting the
flexures. The generality of this rule was shown on the occasion mentioned, by
sections exhibiting the flexures and cleavage in the Appalachians, in the Alps,
and in the Rhenish Provinces; and I have since become convinced of its univer-
sality from the inspection of the phenomena of other districts, and from a study
of the descriptions and sections of geologists. Want of time at present prohibits
me from citing the abundant evidence for this law to be found in the best recently
printed memoirs upon slaty cleavage; but I hope to be able ere long to give my
own observations in support of the highest British geological authorities, who,
unaware of the relationship itself, have furnished the most satisfactory data for
the recognition of it. I cannot, however, refrain, in this place, from sustaining
the generalization I am here venturing to put forth, by instancing the support it
receives from the excellent descriptions recently given by Professors HarKNEss
and Biytu of the Cleavage of tle Devonians of the South-west of Ireland.
In their paper in the Edinburgh New Philosophical Journal for October 1855,
they not only establish an agreement between the strike of the cleavage planes
with that of the several rolls (or anticlinals) which affect the island of Valentia,
but they show that while the cleavage dip is southerly, the anticlinal “ curves
have been pushed over in a more or less northerly direction,” inverting the car-
boniferous limestones and coal measures. Their general statement is, that the
cleavage structure of rocks does not result from the simple rolling of the strata,
but from this cause combined with a considerable amount of pressure; and this
latter force acting from the south, has pressed over the strata in a series of oblique
curves to the north, and given to the inclined cleavage its more or less of a south-
ern dip. They support the doctrine of Mr Suarre respecting the cleavage of

* See Ann. Reports on those Surveys, 1837-40, and other Hssays.
VOL. XXI. PART IIL. 6 E

448 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE:

rocks,—‘ That there has been. a compression in the mass. in a direction every-
where perpendicular to the planes of cleavage, and an expansion of this mass
along the planes of cleavage in the direction of a line at right angles to the line
of incidence of the planes of bedding and cleavage,” or, in other words, to the di-
rection of the dip of the cleavage. From this view of the mechanical nature and
direction of the force engendering cleavage, I beg leave respectfully but explicitly
to dissent.

Fan-like Arrangement of the Cleavage at the Anticlinal and Synclinal Awis Planes.

A second general fact or law of direction of the cleavage planes in folded strata
must be here enunciated. At first view it is in seeming contradiction with the
universality of the primary rule above stated, of the invariable approximate pa-
rallelism of the cleavage planes to the axis planes of the flexures; but closely
examined, it will be seen, I think, to be in beautiful accordance with that law |
and with my hypothesis of the origin of the cleavage structure. The rule is this, :
that where the cleavage is fully developed, and the anticlinal and synclinal flexures |
are also conspicuous and very sharp, the cleavage planes immediately adjoining
those bendings are not parallel to the axis planes, but partially radiate from them
in a fan-like arrangement upward in the anticlinals, and downward in the syn-
clinals.

This aberration from the normal direction is furthermore. different in degree
upon the two sides of the geometric axis plane, being usually greatest upon the
inverted or steep side of the wave.

Fig. 4,

Fan-like Arrangement of Cleavage-at an Anticlinal Axis.
a, Cleavage in the Shale. b, b, Axis Plane,

Another aberration of the cleavage planes from their normal direction of —
parallelism to the axis planes, is their tendency to conform partially to the dip of |
the strata, when the two are nearly coincident. This operates to flatten the
inclination of the cleavage upon the gentler slope of each wave, and steepen it’
upon the more inclined one; and as in every belt of uniform flexures closely
plicated with inversions, the uninverted or normal dips greatly exceed the inverted
ones, it produces in such cases a prevailingly lower inclination in the planes of —
cleavage than in the planes bisecting the flexures.

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 449

Relation of Cleavage to the Mechanical Constitution of the Strata.

There is yet another law respecting cleavage; it is the dependence of this
structure upon the mechanical sextnre, and possibly upon the chemical compo-
sition, of the fissured rocks.

Geologists have for several years recognized the fact, that in formations com-
posed of alternations of the coarser mechanical rocks, such as silicious grits and
conglomerates, with fine-grained argillaceous beds, as slates, shales, or marls,
the coarse beds are unaffected by cleavage, while the fine-grained ones are often
pervaded by it. Indeed, one may observe in a given locality almost.a strict
proportion between the degree of intimate fissuring of the rocks by cleavage planes.
and the degree of comminution of their particles.

Connected probably with this interruption in the distribution of the cleavage-
condition through such heterogeneous groups of strata, I have observed another
general fact of modification of the cleavage planes, which should not be passed
unnoticed here. They tend in the fine grained argillaceous beds, to curve a
little from the normal direction into an approach to parallelism with the surfaces
of bedding of the adjoining coarser mechanical deposits, presenting, in a trans-
verse section, a kind of gentle sigmoid or double flexure. This is well shown in
the cleavage-traversed rocks at the base of the anthracite coal formation of Penn-
sylvania, especially in the transition or passage beds which connect the Umbral
red shales of that region, with the base of the coal-sustaining conglomerate,
and also where these shales alternate with the upper coarser members of the Ves-
pertine sandstone, The small section here appended, showing the cleavage in
one of these groups of alternation of red shale and sandstone, from a railway
cut near Ashland, in the middle anthracite coal-field, exemplifies well the pheno-
menon referred to.

Fig. 5.

site, ps2 a
y: ae ex Nei AR \ DE AAR cK aN Be 77 = ss NaN
Niece AS \ SS SA 2 isi aS on Saw ee

S\ ae

Beds of Red Shale with Cleavage alternating with beds of Sandstone without Cleavage; Cleavage curving towards
parallelism with the bedding at its boundaries. Section near Ashland, Pennsylvania.

The tendency, here shown, in the cleavage planes to conform to the planes of
bedding, where abrupt changes of composition interrupt the continuity of the
fissures, is but another variety of the phenomenon already adverted to, of a de-

450 PROF. H. D, ROGERS ON THE LAWS OF STRUCTURE

flexion of the cleavage in bands of plicated strata towards a parallelism with the
gently dipping slopes of the anticlinal waves. ‘This remarkable fact of an intimate
dependence of the cleavage upon the composition and mechanical texture of the
structure is, I conceive, of itself sufficient to refute the hypothesis somewhat in
favour at present, of the purely mechanical origin and nature of the cleavage-
producing force; for we cannot conceive how a mechanical force, either of com-
pression or of tension, transmitted, as necessarily it must be, very equally through
parallel layers of coarse and fine materials, should have exerted no fissuring action
the moment it reached the surfaces of the coarser beds, and yet have been able to
cleave into thin parallel slaty laminze the whole body of the fine-grained argillace-
ous strata. One would more naturally suppose that the less firmly aggregated
softer mud rocks or shales would have been even less easily fissured by sharp
cleavage joints, than the more massive and better cemented grits. It is of impor-
tance to notice here, that subsequent disruption of the strata may change the
normal position or dip of the cleavage, after its formation, and give rise to some
of’ the apparent deviations from the general law of direction above enunciated.

The Cleavage Susceptibility alternately greater and less in Parallel Planes.

Cleavage is a susceptibility in rocks of a certain composition, and in a parti-
cular stage of metamorphism, to split in definite straight parallel planes. The
cohesive force is obviously at a minimum of intensity in the direction perpendi-
cular to these planes. In the other two rectilinear axes of the cube, one side of
which is coincident with the cleavage plane, the force of cohesion next in degree of
intensity is the horizontal one, or that in the direction of the strike of the cleay-
age, while the most intense cohesion of all is that in the direction of the cleay-
age dip. It is in this latter direction that the molecular forces of attraction en-
gendering incipient crystallization seem to have been most powerfully awakened
while the polarities have been feeblest in the lines perpendicular to the cleavage
planes; but apart from these three directions and grades of corpuscular force, we
have indications, in any homogeneous mass of cleavage-traversed slate, or other
rock, of the presence of two grades of the minimum cohesion, constituting the
cleavability, disposed side by side in alternate parallel order ; in other words, where
the cleavage is fully developed, the rock will be found to contain certain nearly
equidistant closely contiguous planes of maximum cleavability, or, what is the
same thing, of minimum lateral cohesion—the material of each thin plate of the
slate cohering more strongly together than these adjacent plates cohere to each
other. The existence of such planes is indicated by the manner in which any
mass of very cleavable slate, long exposed to atmospheric agencies, invariably
breaks up; as we may see in any naked outcrop. If the cohesion of the mass in
a direction perpendicular to the cleavage planes were equally strong in all parallel
planes that we can imagine pervading it, it is impossible to understand how any

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 451

uniformly acting disintegrating forces,—either expansion and contraction by heat,
soakage and drying, or freezing and thawing,—could subdivide it by planes or
fissures, so regularly distributed as we find them. These could only have arisen, I
conceive, from the presence of parallel planes of weaker and stronger cohesion.
In this interesting structure, we discern a striking analogy to that alternation
of thin plates of solid blue crystal ice, and white porous ice of less cohesion,
which is so distinct a feature in the fully developed ice of glaciers, and which has
been expressively named by Professor James D. Fores, the ribbon structure.*

FOLIATION.

The relations of the foliation or crystalline lamination of metamorphic strata
to the cleavage planes, and the planes of stratification, come next to be considered.
Two facts may be stated of foliation, which possess, perhaps, the constancy of
general laws. One of them is, that this structure, as it is seen in gneiss and mica
schist, observes, when the strata are not traversed by cleavage, an approximate
parallelism to the original bedding. Apparent exceptions to this rule occur in
several localities near Philadelphia, and elsewhere in the United States, and have
often been noticed in Europe, by Mr D. Sarre, and other good observers ;_ but all
of them can be reconciled to the general fact, and reduced, it is conceived, to one
comprehensive law, namely, that the planes of foliation, or the laminz, formed by
the crystalline constituents of the foliated rocks, are parallel to the planes or
maves of heat which have been transmitted through the strata. Wherever large
tracts of the gneissic rocks retain a nearly horizontal undisturbed position, the
foliation is almost invariably coincident with the stratification, and in this case,
the wave of heat producing the crystalline structure can only have flowed upwards
through the crust, invading stratum after stratum, in parallel horizontal planes.
Again, when injections of granite occur in uplifted gneissic strata, the crystalline
lamination is generally seen to be parallel to the plane of outflowing temperature,

* In a communication submitted to the American Association for the Advancement of Science in
1849, I attempted to show this analogy of the ribbon structure of glaciers to the slaty cleavage of
rocks, in the following remarks :—“ The ice of glaciers consists of thin alternate parallel bands or
plates of blue crystal ice, and white porous ice, each not more than one-third or one-half of an inch in
thickness. These pervade the whole mass of every glacier, and are clearly exposed on the sides of
the transverse fissures. Near the sides of the glacier, they are almost absolutely parallel with its
mountain walls, but they sweep away towards its medial line, and form, like all the other planes which
divide the glacier, a series of innumerable loop-like curves. This looped or festooned form is obviously
caused in part by the downward tendency of the movement or flow of the semiplastic ice, and in part by
the influence of the terminal moraine to induce that parallelism to itself, which the rocky sides
of the glacier produce in the ice near them. The most general fact noticeable in relation to these
structural planes, is the approximate parallelism to the rocky walls and terminal moraine confining
the icy mass; or in other words, to the surfaces of higher temperature, which inclose the glaciers.
However the direction of the ribbon lines may alter by irregularities in the onward flow of the glacier,
their position near the region of the nevé is strictly parallel with the surface of the warmer mountain
sides.”

VOL. XXI. PART III. OF

452 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

The other general rule is, that the foliation is parallel or approximately so to the
cleavage, wherever these two structures occur in the same mass of rocks. This
fact, recorded by Darwny, of the gneissic rocks and clay slates of South America,
has been noticed likewise by Mr D. Saarre, Mr Davip Forpes, Mr Sorsy, and
other geologists in Great Britain, and by the author, in many localities in Southern
Pennsylvania, and in other districts of the Atlantic Slope. An interesting in-
stance of such parallelism of the foliation to the cleavage, tending to show con-
vincingly, that both phenomena are the consequences of one species of force, or
only different degrees of development of the same molecular or crystallizing
agency, is presented in the great synclinal trough of the lower Appalachian lime-
stone, north of Philadelphia. On the north side of this trough, the Primal and
Auroral rocks dip southward over a wide outcrop at a very regular angle of about
45°. On the south side they have been lifted into, and even a little beyond, the
perpendicular position, so that the synclinal axis plane of the belt dips at an
angle of 65° or 70° to the south. Neither formation shows cleavage structure on
the northern side of the valley, the limestone being there of an earthy texture,
and in thick massive beds, but on the south or upturned side, this limestone is
altered into a mottled blue and white crystalline marble, and is pervaded with
cleavage planes, dipping at angles of 70° and 80° southward. Many parts of the
rock are like a foliated calcareous gneiss, thin lamine of mica and tale dividing
the slate-like plates of the marble. It is especially worthy of notice that the
foliation of these mica and talc, composing some of the thin partings between the
original beds of the limestone, is itself very generally parallel to the cleavage in
the adjoining calcareous rock. Indeed, wherever the cleavage is excessive, the
mass becomes, by introduction of fully developed talc and mica between its lamineze,
a true foliated stratum. An especial interest annexes to cases of this kind, from
their showing, that in the two contrasted conditions of the absence and presence of
metamorphism in the two opposite outcrops of the same synclinal fold, both effects,
cleavage and foliation, have originated at the same time, and from one and the
same cause, and are, in truth, but different stages of the same crystalline condi-
tion, superinduced in the mass by high temperature, at the period of its elevation.
The above general fact of the prevailing parallelism of the foliation to the clea-
vage, is but a corollary of the more general relationship already expressed of the
parallelism of the resulting planes of crystallization to the waves of heat, which
have produced the metamorphism.

EXAMINATION OF THE PREVAILING THEORIES OF ELEVATION.

Perhaps the most current notion respecting the force which has displaced and
elevated the originally horizontal strata of the globe, is that which represents the
granitic and volcanic rocks as forcibly injected in a melted state into fissures, and

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 453

violently thrust in solid wedge-shaped masses upwards through the incumbent
crust. That this is the prevailing idea, is apparent from the manner in which
nearly all geological sections, even the most modern ones, designed to represent the
relations of the Plutonic to the sedimentary rocks, are to this day constructed.
Where igneous rocks constitute the whole, ora large portion of the central axis of
a mountain chain, or even that of a simple anticlinal ridge, they are usually
represented in cross sections, in the form of a broad wedge, and the stratified rocks
are drawn as leaning upon the sloping flanks of the wedge or prism. This is not,
I think, the true relation in Nature of the igneous to the sedimentary masses, as I
propose to show from the following considerations.

Hypothesis of Wedge-like Intrusion of Melted Matter.

The notion of an upward wedging, or intrusion of molten mineral matter into
or through the superincumbent strata, in the manner of a wedge, implies a func-
tion in the soft material which belongs to the mechanical action of a solid, and
is incompatible with the dynamic properties of fluids. Until a fissure from below
first penetrates or traverses the invaded overlying strata, it is not possible to con-
ceive, that the liquid matter could introduce itself in the mode of a wedge. Some
force must first crack the crust, and then the molten matter, flowing into the fissure
may act as a narrow wedge or key, to keep the walls of the chink distended, but
such plates of solidified refrigerated volcanic matter, known as veins and dykes,
must necessarily be narrow, and have the shape rather of walls with parallel sur-
faces, than great wedges broad at the base.* They will also abound chiefly in the
districts of subsidence, or in the concave waves, not in those of elevation, or in
the convex, where the wedge-like form tapering upwards, is usually represented.
Where a rupturing of the strata has taken place in a tract of elevation, or at
an anticlinal, the fissure or fissures will be found to gape upwards, and the
melted volcanic matter which has flowed to the surface, will be seen widen-
ing outwards and tapering as it descends, the very opposite of the form usually
assigned to such outbursts, in the igneous axes of uplifted chains. So common
is this upward enlargement of the Plutonic masses in certain regions, that it con-
stitutes, I conceive, one element of the fan-shape or inward dip of the boundary
walls of the rocks, so frequently encountered in the Alps and other much dis-
turbed mountain systems. A true conception of the formation of a mineral vein
or dyke will represent it as the consequence, not the cause, of the fissure which it
fills, the real process being, not a protrusion of the fluid matter through the crust,

* Tt is in consequence of this natural expansion of surface-cracks outwards in anticlinals, that
the miner so frequently finds his mineral lodes contracting or dying out as he descends. Several
striking instances of this thinning of veins downwards could be cited, from the mines of the United
States, situated in anticlinal flexures.

454 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

breaking it in its passage as a solid wedge might, but an actual injection or pump-

ing of it into the newly opened vacuous cavity, from the pressure or tension below.
Fig. 6.

Dykes expanding upwards in Anticlinals and downwards in Synclinals.

Intrusion of the Igneous Rocks in Solid Wedges.

The other notion, frequently connected with the above idea, of a forcible pro-
pulsion of igneous matter through the crust, is that of the violent thrusting
upward of volcanic or granitic matter already solidified, in broad wedge-like masses
through the strata. This conception I hold to be at variance both with sound
mechanical laws, and with the physical facts. For the solid igneous mass to have
acted in the manner of a wedge, it is absolutely necessary that it should have
moved freely upward through the opening in the strata, which it is supposed to have
wedged apart and to have uplifted, and even corrugated, by lateral compression.
But it is impossible to imagine such a slipping of the assumed granitic wedge
past the edges of the strata confining it, since we can imagine no force acting
downward upon these latter, to prevent their moving upward along with the
wedge of granite, nor any localization of the force below, to prevent it operating
on both alike. We have furthermore no evidence of that discontinuity between
the igneous rock and the ruptured strata, which the notion of a sliding wedge
obviously presupposes; but, on the contrary, every proof from general theory and
from observed facts, that the two descriptions of rock are intimately bound to-
gether in closest crystalline contact, keyed together by veins, branching from the
mass of the one into the fissures of the other, and even fused together by an
actual incorporation of substance. Any upward movement, therefore, of Plutonic
masses, bearing sedimentary rocks upon their flanks, cannot have been in the
manner of a mechanical wedge; and those results—corrugation for example—of
the adjacent strata habitually attributed by many geologists to an imagined
wedge-like lateral thrust, must be accounted for upon some other sounder me-
chanical theory.

A modified form of this conception of an igneous wedge lifting and displacing
the strata, assumes no sliding or wedge-like protrusion of the solid granitic matter
past the edges of the rupture in the bedded rocks, but recognizing the inseparable
cohesion of the two, regards the stratified masses flanking the anticlinal mountain,
as merely borne upward by the uprising of the central igneous nucleus. I deem
this notion to be a much truer picture of the procedure of nature; for it so far
accords with what we notice in anticlinal districts having igneous crests or centres,

OF THE MORE DISTURBED ZONES OF THE EARTH'S CRUST. 455

that it represents the stratified rocks leaning against the walls of the great granitic
central dykes, at steeper and steeper angles, the higher we ascend towards the
summits. It is inexact, however, in picturing the granitic nucleus of the anti-
clinal mountain, as a wedge or broad prism tapering upward, for reasons already
shown. Undoubtedly such a mountain, if we can imagine it denuded or truncated
to lower and lower levels, would disclose a progressively increasing quantity of
intrusive igneous rock, but this would be in the multiplication of the lateral
granitic injections, and it is only in this erroneous sense, that the igneous nucleus
can be regarded as a prism. Its cross section is branching rather than wedge-
like.

The Upward Movement of an Igneous Dyke would tend to Stretch and not to Corrugate the
Flexible Strata.

The view here admitted of the elevation of the igneous nucleus of a mountain,
along with the strata which mantle it, while it is perfectly compatible with the
hypothesis, to be hereafter advanced, of the origin of anticlinals generally, is wholly
inconsistent with the somewhat current notion of the mode of origin of undulations
and plications in the stratified rocks, by pressure from the tangential horizontal
thrust of such uprising igneous axes; so far from its producing a lateral corrugating
pressure upon the strata adjoining, and resting against it, a central granitic or
other igneous dyke lifted vertically by one or many successive movements, pa-
roxysmal or gradual, would rather stretch or distend the strata as it carried them
upward than compress them.

Theory of Upward Tension against Lines or Points of the Crust.

Another common theory of crust movement and elevation of anticlinal belts
supposes, vaguely, an upward tension or stretching of the crust of the earth along
one or several lines, or at one or several focal points, without attempting to ac-
count for the linear or focal force, or to assign a cause for the restricted limits
within which it is assumed to act. This conception, though confessedly indis-
tinct, is frequently appealed to in explanation of the lifting of mountains, the
corrugation of strata, and even the formation of regular groups of parallel anti-
clinal waves. I propose to consider its weak points.

Any theory henceforth admissible into physical geology, must explain the now
clearly established general fact of the regular wave structure of the earth’s dis-
turbed zones. But this wave structure cannot be interpreted on the mere sup-
position of simply an upward pressure exerted either along one or many lines. The
peculiar configuration of the crust waves, shown in this paper to be characteristic
of them in all undulated regions, requires an hypothesis which will furnish both
an undulating and a horizontal tangential motion; moreover, the ordinary doc-
trine, if it assumes the pressure from beneath to be exerted along a single line at

VOL. XXI. PART III. 6G

456 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

a time, fails altogether to show us how this pressure could have shifted to new and
parallel lines, or how it could take up new positions, and exhibit that relation
of relative distances constantly widening, which is seen in all undulated belts.
Besides, how could a simple upward pressure along a line in the crust, form a
defined or limited anticlinal flexure? Whether the pressure were exerted by a
liquid or a solid subterranean mass, it would produce rather a wide general
moderate elevation, than a narrow, sharp, anticlinal wave.

If, again, this vague theory be modified to admit the action of a series of
linear simultaneous pressures, coincident with the observed anticlinal flex-
ures of an undulated district, it is not possible to understand why, being conti-
guous, they should not all conspire to lift the outer mass or crust into one
general bulge or broad distended dome, rather than into a series of alternately syn-
clinal and anticlinal waves. In addition to these difficulties, this notion of self-
awakened lines of pressure, contains no clear hypothesis of the origin of the linear
forces.

Hypothesis of Corrugation from Sinking of Tracts of the Earth's Surface.

Another theory of the cause of flexures in the Crust conceives them to have been
produced from a sinking of the ground by removal of matter by volcanoes, or by
the contraction of argillaceous rocks by heat and pressure. Sir C. LYELL, who
appears to advocate this view, supposes that pliable beds may, in consequence of
unequal degrees of subsidence, become folded to any amount, and have all the ap-
pearance of having been compressed by a lateral thrust; and the creeps in coal-
mines are adduced as affording an excellent illustration of this fact.* With every
respect for this eminent geologist’s ingenious views, I must confess that this con-
ception seems to me quite as much beset with difficulties as the somewhat kin-
dred theory of elevation and simple upward protrusion. Apart from the objec-
tions that it supplies no cause for the peculiar shape of the crust waves, nor any
explanation of their parallelism, and their remarkable laws of gradation, it appears
to me quite inadequate to account for lateral corrugation at all, or for more than
a very insignificant amount of it. A downward pressure or tension over a single
area, produced by release of support arising from vacuities beneath the surface,
ought not to engender, on any known mechanical principle, a series of flexures,
either within or around the area, but should result in a mere subsidence or flat-
tening of the portion from whence the support has been withdrawn. If the
centering of a very flat dome, too weak to sustain itself, be removed, the dome
either suddenly collapses with a fracture, or it indents itself, and sinks where it
is weakest and most yielding, till it meets the supporting floor. Before the wide
nearly level dome of a segment of the earth’s crust can corrugate either itself

* See Lyeri’s Elementary Geology, 5th Ed., p. 50.

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 457

or the adjoining strata, some alternate upward and downward force must undu-
late them, or they must contain alternate weak and strong belts, and even then
these must be somewhat undulated ; none of which conditions the hypothesis of
subsidence is prepared to supply.

Hypothesis of a simple Horizontal Compression.

A somewhat favourite and familiar mode of accounting for the undulation and
plication of strata, is that which assumes them to have been corrugated by a purely
horizontal or tangential pressure, without elevation and without pulsation; and
this imagined mode of folding has been ingeniously illustrated by Sir James Hatt,
Sir H. Dexa Becue, and other geologists, by their placing flexible layers of clay, or
cloth, or other substances, horizontally under a weight in a trough, and forcing
one or both ends towards the centre, so as to contract the length of the strata, and
thereby produce a series of miniature plications. It has been alleged that this
folding of the clay or cloth is an exact imitation of the flexures of strata seen in
nature; but I must deny the assumed analogy. ‘The plications thus produced
are merely irregular contortions; they exhibit no definite form of curvature, no
constancy in the direction of their gentler and steeper slopes, and no law of
regular gradation. Their anticlinal and synclinal axis planes, if they can be said
to have any, lean some one way and some another; and the flexures, when the
crowding is great, have a tendency to the horse-shoe form, and not to that of
waves.

This hypothesis of corrugation, while erroneous in thus failing to present
a true representation of the waves of the crust, is also defective in its me-
chanical principles, for it assigns no cause for the origination of the wave struc-
ture. A purely lateral or horizontal force should, as already intimated, simply
bulge out to a feeble extent the whole compressed arch, but ought not of itself to
wave it; some independent agency, producing alternate upward and downward
flexure is indispensable to give even the most powerful tangential pressure the
ability to plicate the flexible mass. This hypothesis is furthermore imperfect in
not suggesting any cause in nature for the assumed horizontal pressure. It has
been already shown, when discussing the hypothesis of simple elevation, and of
simple subsidence of areas of the earth’s crust, that neither of those movements,
unaccompanied by an actual pulsation of the strata, would be competent to cor-
rugate the crust at all; the pure elevation of an igneous axis having the tendency
to stretch rather than compress the adjoining strata; and the simple sinking of
an area, by retreat of support beneath, having only the effect to irregularly warp
the surface, but in nowise to undulate it.

458 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

VIEWS OF GEOLOGISTS CONCERNING CLEAVAGE AND FOLIATION.

Professor SED@WICcK, as early as 1822, discovered and subsequently publicly
taught the true nature of slaty cleavage, distinguishing it from joints, and show-
ing it to be a tendency to separation in perfectly parallel planes, which are irre-
spective of the bedding. He ascertained that the slaty cleavage is usually con-
fined to the finer-grained rocks, alternating coarser beds possessing it very im-
perfectly, and laid it down as a rule, that the strzke of the cleavage is nearly
coincident with the strike of the beds He referred it to crystalline or polar forces
acting simultaneously and somewhat uniformly in giving directions. Subsequently,
Professor SepGwick in 1835,* after many additional observations on the modifica-
tions of slaty cleavage, showed that the rule admitted of many limitations, which
the geologist is compelled to notice in working out the structure of complicated
districts. In a recent publication, his “Synopsis of the Classification of the
British Paleeozoic Rocks,” he shows conclusively, that the cleavage structure is
‘‘ the compound effect of all the crystalline forces acting on the mass, and that it
cannot be due to a mechanical action.’ In this work, he also mentions the im-
portant fact of the existence frequently of a second cleavage plane, generally in-
clined at a great angle to the primary.

Sir J. Herscuet has suggested that the rocks possessing cleavage may have been
so heated as to allow a commencement of crystallization, or heated to a point at
which the particles may have begun to move among themselves, or on their own
axes; surmising that some general law has determined the positions on which
the particles have rested on cooling, and that this position has had some relation
to the direction in which the heat escapes.+

Professor Pixies {t has shown, that in some slaty rocks, fossil shells and tri-
lobites have been much distorted by cleavage; and he imputes this to a creeping
movement of the particles of the rocks along the cleavage planes. This displace-
ment, uniform over the same tract of country, he states to be as much as a
quarter or even half an inch. MHard shells are not thus affected, but only the
thin ones. Professor PHituips, in 1843, stated that the cleavage planes of the
slate rocks of North Wales are cleavages parallel to the main direction of the
great anticlinal axes.

Mr Dante Suarre conceives that the present distorted form of the shells in
certain slates, has been produced by a compression in a direction perpendicular
to the planes of cleavage, and an expansion in the direction of the cleavage dip.§

He conceives that the planes of cleavage range vertically along certain
lines or belts, and dip towards those lines on each side of them; those nearest
the central vertical belts at high angles, the angles gradually diminishing as

* Geol. Trans., 2d Series, iii., p. 461. + Liyertt’s Manual, p. 610.
t Report British Association, Cork, 1843. § Quarterly Jour. Geol., vii., p. 87.

Ni i

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 459

the distance from the vertically dipping cleavage increases. This is his expla-
nation of the fan-like arrangement of dip noticed in some countries. “This
regularly descending series of planes being found on each side of parallel lines of
vertical cleavage, the two series either meet in the centre in a sort of anticlinal
axis, or coalesce into an arch. The planes between two lines of vertical cleavage
appear to form a complete whole, and the area bounded by the vertical cleavage,
may be considered as belonging to one system of cleavage, and may be called an
area of elevation of the cleavage.” He thinks the cleavage planes are really parts
of great curves, which, if completed, would represent a series of semicylinders
turned over a common axis.

Mr SuHarpe thinks “ that there is reason to believe that all slaty rocks have
undergone a compression of their mass in a direction perpendicular to the planes
of cleavage,” connecting with this view his supposition that the cleavage areas are
great anticlinal waves. He supposes that the compression of the slaty mass, and
its expansion in the direction of the cleavage dip, have been due to the stretch-
ing of the strata in the direction of the curve representing the cleavage dips.

Mr Cuartes Darwin, * reviewing his observations on cleavage in South Ame-
rica, says,—‘ The cleavage lamine range over wide areas with remarkable uni-
formity, being parallel in strike to the main axes of elevation, and generally to
the outlines of the coast.”” He recognizes the fact that the cleavage planes fre-
quently dip at a high angle inwards, and he cites an instance of cleavage dip, in
the mount at Monte Video, where. “ hornblendic slate has an east and west
vertical cleavage, with the laminze on the north and south sides near the summit
dipping inwards, as if the upper part had expanded or bulged outwards.” Mr
Darwin first proposed the term foliation for the laminz in gneiss and other crys-
talline rocks, or the alternating layers or plates of different mineralogical compo-
sition. He pointed out the parallelism: of the planes of foliation of the mica
schists and gneiss with the planes of cleavage of the clay-slate in Tierra del
Fuego and Chili, as seen by him in 1835. Darwin conceives that foliation may
be the extreme result of the process of which cleavage is the first effect, or that
the crystalline form may have been most energetic in the direction of cleavage.
He further suggests, “that the planes of cleavage and foliation are intimately
connected with the planes of different tension to which the area was long sub-
jected, after the main fissures or axes of upheavement had been formed, but be-
fore the final cessation of all molecular movement,” “ and that this difference
in the tension might affect the crystalline and concretionary processes.”

Mr Sorsy, adopting the mechanical theory of cleavage, maintains that it
varies directly as the mechanical changes, and inversely as the chemical (mole-
cular) changes, which the strata have undergone. He thinks he has shown that
the cleavage of certain limestones, microscopically examined by him, varies di-

* See Geological Observations on South America.
VOL. XXI. PART III. 6H

460 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

rectly as the amount of mechanical compression to which they have been sub-
jected, and that this compression was such as would necessarily change the struc-
ture of uncleaved into cleaved rock. He alleges “that cleaved limestones pos-
sess no crystalline polarity,” and that in place of crystallization producing slaty
cleavage, it has a contrary tendency, and, when perfect and complete, obliterates
it altogether. Mr Sorsy conceives that the absolute condensation of the slate
rocks amounts, upon an average, to about one-half of their original volume.* This
condensation he ascribes to the forcing together of the particles, and the filling
up of their interstices by pressure perpendicular to the cleavage, and partly by
elongation in the direction of the cleavage dip.

Mr Davin Forzes,t+ writing upon foliation in rocks, leans to the conclusion
that foliation is a distinct phenomenon from cleavage, and that the causes pro-
ducing them were also distinct. He refers the foliation to chemical action, the
cleavage to mechanical pressure. He admits that the planes of foliation and
those of cleavage are often parallel to one another.{ But the parallelism of the
foliation to the cleavage he ascribes to a previously induced cleavage structure
facilitating crystalline lamination in its own planes.

He supposes foliation to have resulted from a chemical action combined with a
simultaneous arranging molecular force, developed at heats below the semifusion
of the mass; also that the arrangement of foliation is often due to the proximity
of igneous rocks, and tends to follow the direction of any lines in the rocks where
the cleavage stratification, or strice of fusion, follow preferably those lines offering
least resistance. .

Examination of the Prevailing Theories of Cleavage and Foliation.

From the theory of the origin of cleavage by mechanical compression exerted
perpendicularly to the cleavage planes, as adopted by Mr Suarpr, Mr Sorsy, Mr
Davip Forbes, and other geologists, [am constrained to dissent, and upon the
following grounds :—

1. It has been already shown, in the general description of the phenomena of
cleavage, that this tendency of fissuration is stronger and weaker in alternate
closely contiguous planes, and is not diffused equally, even in the one direction,
through the mass. Now it is impossible to conceive how a purely mechanical
compression could have occasioned a regular alternation of greater and less con-
densation of particles, all equally free to move and adjust themselves into posi-
tions of statical equilibrium, and all equally subjected to the same amount of
force. The well-known law of a quaquaversal tension of fluids is manifestly ap-
plicable to partially soft and flexible rocky matter, if we are to impute to this an

PweUL, p: G12: t See his Paper, Quarterly Journal, Geological Society, 1855.
+ See his Paper for a good figure of deflection of cleavage and foliation in the margin of a vein of
quartz.

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 461

actual rotation of its parts, such as the mechanical theory assumes; and I cannot
see why one uniform condition of aggregation should not be the result.

2. In the second place, it assigns no reason for the presence of cleavage planes
in fine-grained argillaceous and calcareous rocks, and their absence in silicious
ones, both fine-grained and coarse, even when the two classes alternate with each
other in intimate parallel contact, where they must have been exposed to precisely
the same pressure, both in direction and in amount. In other words, there is no
relation discoverable between the known susceptibility of different materials to
cleavage, and their susceptibility to compression. But on the other hand, some
of the most compressible are the Jeast subject to this peculiar structure. The
different susceptibilities of different kinds of mineral matter to molecular polarity
is, I conceive, the true explanation of this marked contrast in rocks.

3. Another quite conclusive objection, I conceive, to the pressure theory of
cleavage is, that it fails to show how the cleavage-traversed strata can have re-
ceived the pressure in one constant direction, and under an equalized intensity,
through all the contortions and bendings which we know they must have pos-
sessed before cleavage was imparted to them. It is obvious that no mechanical
pressure, come from what quarter it might, could transmit itself uniformly
through convex and concave curves, through bodies of rock placed edgewise and
flatwise towards it; but, on the contrary, dynamic considerations must convince
us that the resultants of such a pressure would be as various in their directions
within the mass, as the ever-changing planes of the corrugated stratification. Not
only would the posture of the strata at any point next the quarter of the primary
pressure influence the form and direction of the resultant planes of pressure
at that point, but the differences in pliability of the different layers compressed
would greatly modify them. In other words, while the dip of the cleavage planes
within even wide limits, is usually remarkably constant, whatever the contor-
tions of the strata, any pressure transmitted through these contortions must be
as various, in different portions of the flexures, as the innumerable resultants pro-
duced by the ever-varying resistances and the pressure combined.

4. A like difficulty opposes itself to the pressure theory, in the constancy of
the direction of the elongation or stretching of the mass in the line of its
cleavage dip. This extension, well expressed by Professor PHiniips asa “ creep-
ing movement of the particles,” seen not only in the fibrous grain of cleavage
slates, but in the distortion of imbedded fossils, and of the whole substance
of the rock indeed,—ascribed to mere compression by the authors above cited,
but attributable, I think, to an actual molecular movement of the mass, in
obedience to crystallizing polar forces,—is so equally graduated in amount, and
so wonderfully constant in direction (never deviating much from the line of dip
of the cleavage plane), that it could never have acquired this constancy from a
merely lateral mechanical force, liable to infinite modification, in both of these

462° PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

respects, by the continually varying resistances consequent on the contortions of
the beds.

5. A further objection lies against the pressure theory, in the contradiction it
offers between the direction which it assumes the compression to have come from,
and the direction in which we can demonstrate the strata to have been actually
pressed and moved. In every district of plicated and undulated strata, it can be
shown, from the shape of the waves, from the declension in their curvature and
height, from their mutual recession, from abatement in all the metamorphic
signs of igneous action, and, finally, from the direction of the great planes of
fracture in the crust, that the movement and pressure were upward and forward
from the quarter of chief crust disturbance. Now itis nearly at right angles to this
established direction of the forces, that the hypothesis I am reviewing assumes a
pressure to have been applied to produce the cleavage. The planes of fissuration
dipping inward towards the igneous side of the belt, any cleavage-producing pres-
sure to be perpendicular to these planes, as the theory alleges it was, must have
come either from a point or line elevated at least 45° above the earth’s surface, or
else from a point or region far below the earth’s crust on the opposite side, or in the
quarter where the cleavage is absent, or is invariably the least distinct, and where
the flexures of the strata, and all other evidences of crust movement, are vanish-
ing. This is, I conceive, a dynamic dilemma in which the compression theory
finds itself,—either to make the force emanate from a quarter external to the
crust entirely, or from just that quarter where we have the fullest evidence of the
absence of any force at all. Thus, if the theory is applied to explain the south-
dipping cleavage of the northern flank of the Alps, it implies either that the pres-
sure came, not from within the crust below the crest of the chain, but from some
point in the air high over the summits of the mountains, or else from some deep-
seated subterranean region far to the north of the Alps, under the undisturbed
plains of Northern Switzerland or Germany. In the case of the Appalachians, it re-
quires that the pressure should have come, not from under the convulsed and rup-
tured region of the Atlantic slope, but from some high aerial point above this, or
else from a spot diametric to it, deep under the plains of the Western States, where
neither cleavage, metamorphism of any kind, nor undulations of the strata exist,
to indicate the former presence there of any compressing force at all. (See Sec-
tions of the Appalachians and Alps. Figs. 1 and 3.)

6. Besides this general difficulty, I have a special one to offer connected with
the laws of cleavage dip. This applies not only to the theoretical generalization
of Mr Dante SHARPE respecting the relations of the cleavage planes to each other
in different parts of a zone of slaty cleavage, but to the observations upon which
his generalization has been built. His sections of the cleavage in North Wales and
elsewhere, represent it as perpendicular or steepest in the belts of maximum ig-
neous action, and flattest in the regions most remote from these, where he places

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 463

the anticlinal axes of his cleavage curves. Now, just the reverse of this steepen-
ing of the cleavage planes towards the regions of chief metamorphism, will be
found to be the real law of gradation in the Appalachians, the Alps, and the district
of the Ardennes and Southern Belgium. Obedient to a law already explained, the
cleavage dip, following the dip of the axis planes of the flexures, is not most but
least inclined in the districts most convulsed, and grows progressively steeper,
as we advance across the undulations to the districts of minimum disturbance.
In the Alps the plications lie flattest next the high central crests of the chain,
and there the cleavage dip is often at a very low angle; but receding towards
the plain of Switzerland, where the theoretical view requires that it should
be flatter, it is really steeper, and even approaches to perpendicularity; and
precisely analogous is the gradation when we cross the Appalachians from
south-east to north-west. Generalizing the dips of the cleavage planes on both
sides of a double belt of flexures like that of the Alps, and excluding the central
crests, where the jointage of the igneous rocks, and the cleavage structure im-
pressed by them is more vertical, the real curve of dip for the whole zone will be
found to be a synclinal one, and not the two halves of two anticlinals, the gener-
ating axes of which are far outside the chain, one in the plain of Switzerland,
the other in the plain of Northern Italy.

I am much gratified to find, that my objections to the mechanical theory of
cleavage find support in the able writings of Professor SepGwick, who, in a note
in his “ Synopsis,’ states several cogent reasons for rejecting the hypothesis.
While some of my own objections are but an expansion of those presented by this
eminent geologist; others are independent of his, growing out of my own observa-
tions. This accordance gives me additional confidence in the soundness of the
generalizations upon which they rest.

THEORETICAL VIEWS.

Theory of the Flexure and Elevation of Undulated Strata.

The wave-like structure of the Appalachians and other undulated zones, has
been attributed by the author and his brother, W. B. Rogers, in their communi-
cations to the American Association in 1842, and tothe British Association in the
same year, to an actual undulation of the supposed flexible crust of the earth,
exerted in parallel lines, and propagated in the manner of a horizontal pulsation
from the liquid interior of the globe. We suppose the strata of such a region to
have been subjected to excessive upward tension, arising from the expansion of
molten matter and gaseous vapours, the tension relieved by linear fissures, through
which much elastic vapour escaped, the sudden release of pressure adjacent to the
lines of fracture, producing violent pulsations on the surface of the liquid below.
This oscillating movement in the fluid mass below would communicate a series of

“ VoL. XXI. PART IIL. 61

464 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

temporary flexures, to the overlying crust, and these flexures would be rendered
permanent (or keyed into the forms they present) by the intrusion of molten matter.
If, during this oscillation, we conceive the whole heaving tract to have been shoved
(or floated) bodily forward in the direction of the advancing waves, the union
of this tangential, with the vertical wave-like movement, will explain the peculiar
steepening of the front side of each flexure, while a repetition of similar operations
would occasion the folding under, or inversion, visible in the more compressed
districts. We think that no purely upward or vertical force, exerted either simul-
taneously or successively along parallel lines, could produce a series of symmetrical
flexures, and that a tangential pressure unaccompanied by a vertical force, would
result only in an imperceptible bulging of the whole region, or an irregular plication
dependent on local inequalities, in the amount of the resistance. The alternate
upward and downward movement necessary to enable a tangential force to bend
the strata into a series of regular parallel subsiding flexures has been, we conceive,
of the nature of a pulsation, such as would arise from a succession of actual waves
rolling in a given direction, beneath the earth’s crust. It is difficult to account
for the phenomena, by any hypothesis of a gradual prolonged pressure exerted
either vertically or horizontally. The formation of the grand, yet simple flexures
so frequently met with, cannot be explained by a repetition of feeble tangential
movements, since these could not successively accord, either in their direction or
in their amount, nor can it again, by a repetition of merely vertical pressures, for
it is impossible to suppose that these could, without some undulating action, shift
their positions through a series of symmetrically disposed parallel lines. We
find it equally impossible to understand how, if feeble and often repeated, these
vertical pressures should always return to the same lines to produce the con-
spicuous flexures we behold. The oscillations of the crust to which the undula-
tions of the strata are attributed have been, we conceive, of the nature of the
Earthquakes of the present day. Earthquakes consist, as we think we have de-
monstrated, of a true pulsation of the flexible crust of the globe, propelled in
parallel low waves of great length and amplitude with prodigious velocity, from
lines of fracture, either conspicuous volcanic axes, or half concealed deep-seated
fissures, in the outer envelope of the planet.

Theory of Cleavage Structure.

Concerning the cause of slaty cleavage, I have adopted the explanation origi-
nally proposed by Professor SepGwick, that it is due to crystalline or polar forces
acting simultaneously and somewhat uniformly in given directions on large masses
having a homogeneous composition. And following up the further suggestion in
extension ofthis idea ingeniously proposed by Sir Joun HeErscHeEt, that this
molecular force was of the nature of an incipient crystallization, and has been

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 465

developed in the particles, by their being heated to a point at which they could
begin to move among themselves, or upon their own axis, I have endeavoured
to show, that whether the cleavage-traversed strata have been much disturbed or
not, the cleavage planes invariably approximate to parallelism with those great
planes in the crust, which appear to have been the planes of maximum temperature.
It has been already stated in the present paper, that the cleavage dip is parallel
to the average dip of the anticlinal and synclinal axis planes, or those bisecting
the flexures. Now, it is easy to prove, that these axis planes, and the inverted
parts of the flexures, are just those portions where the greatest wrenching, fissur-
ing, and opening of the strata must have occurred, and where the highly-heated,
pent up, volcanic steam and gases, and liquid mineral matter, must have found
their chief channels upwards to the surface.

Without attempting at present to apply this doctrine in detail, I will content
myself with reviving a suggestion I formerly put forth, that every plicated belt of
strata may be looked upon as having, from the causes here adverted to, become
traversed at the time of their folding and metamorphism, by a series of alternate
hotter and cooler parallel planes or zones of temperature, arranged in oblique dip,
coincident approximately with the axis planes of the fiexures. These planes or
surfaces of high temperature, we may suppose to have acted to polarize the par-
ticles in correspondiny planes, by transmitting through the half-softened mass, a
succession of parallel waves of heat, stimulating the molecular crystallizing forces,
which are ever resident in mineral matter, and which only await there the quicken-
ing influence of such a temperature, to develop in the mass special lines and
surfaces of maximum and minimum cohesion.

This conception, that the surfaces or planes of crystalline lamination, includ-
ing cleavage, which is but a lower grade of the same species of molecular meta-
morphism, are approximately parallel to the surfaces of the waves of temperature,
which have moved through the strata, is not a mere hypothetical speculation,
but an induction at which I have arrived, from a comparison of many obser-
vations of my own, with phenomena well recorded by the ablest geologists.
Nearly all observers who have noted the influence of igneous dykes and veins
upon the strata adjoining them, both in mines and external exposures, have seen
amore or less distinct lamination or cleavage adjoining the walls of the once
heated mineral matter, and have been struck by its very general parallelism, to
the surface or the axis of the vein. Cases occur in strata of all ages, and are
frequently brought to light in coal-fields, when nearly vertical dykes cutting low
dipping or horizontal shales, susceptible of the cleavage metamorphism, have
occasioned in the latter a true cleavage perpendicular to the stratification, or
parallel, more strictly speaking, with the once hot surface of the intrusive
rock.

466 PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

Fig. 8.

<ADU)
SLUT PAN
or

el. 85°W 70°

wt
p.0?

Cleavage superinduced by a Trap Dyke in Red Argillaceous Sandstone of J ae age, west of Gettysburg, Pennsylvania.
Other instances are often presented of masses of superincumbent trap rock, baking
and altering argillaceous and other strata, in which a like law of parallelism of
the cleavage to the heat-imparting surface of the molten matter is shown in the
horizontality of the cleavage planes, whatever be the dip of the strata. Numerous
examples can be cited, where one igneous dyke cutting another, or traversing a
mass of earlier Plutonic rock, produces in the latter a crystalline grain, amounting
to a sort of cleavage, adjoining the bounding surfaces of the newer injection, and
in planes invariably parallel, or nearly so, to the walls of the fissure. A similar fact
of the occurrence of a cleavage parallel to the walls of highly heated fissures, may
be seen in the faults and great dislocations which traverse some parts of the anthra-
cite coal basins of Pennsylvania. Here the greatly indurated argillaceous shales,
and even sometimes the coal itself, display a cleavage-structure invariably parallel
to the general plane of the fracture. Such fissures would be the natural channels
through which heated volcanic steam would ascend from the interior, and the
action of this upon the strata most susceptible of cleavage would be precisely
analogous to that of a molten dyke, in transmitting a wave of heat perpendicular
to its surface, partially softening and half polarizing the matter as it passed.

* There is a similar instance cited by Professor Puitures, I think in his Geology of Yorkshire.

ee

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 467

General Resumé.

1. Wave-like form of all belts of uplifted strata.

a. lt is a general fact that strata dip in curved and not in straight planes.

b. Wherever wide areas of the crust have been elevated or depressed from the
level at which their strata were deposited, these strata will be found, except
where their dip is disordered by crust dislocations, to constitute, in their vary-
ing angles of dip, one or more wide regular curves.

2. Parallelism of crust undulations.
a. It is another general fact, that these undulations of the strata are in the form

of long parallel waves, resembling much those great continuous billows called
im dynamics waves of translation, and by seamen rollers.

3. Relations of flexures.
a. Parallelism of the waves to the general trend of the part of the mountain sys-

tem to which they belong, and especially to its chief igneous axis.

b. Parallelism of flexures extends not only to adjacent individual waves, but to
contiguous groups, and is as true of curvilinear as of straight.

c. The waves of the strata are generally of two or three grades of magnitude, as
respects their length, height, and amplitude, and while those of the same grade
are parallel, the different grades are not necessarily so.

4. Laws of form and gradation of waves.

There are three characteristic forms of crust waves ; symmetrical flexures equally
steep on the two slopes; normal flexures, curving more rapidly on one side
than on the other; and folded flexures, or those with a doubling under of their
more incuryed slopes, and among which the steepest slopes are generally directed
to the same quarter.

The geometric planes bisecting the anticlinal and synclinal bends of the strata,
here called axis planes, are nearly perpendicular in the symmetrical waves, but
inclined in the other two classes, dipping at the lowest angle in the folded
flexures. In many belts the plication is such as to amount to parallelism of
all the inverted to the uninverted sides of the waves.

Some waves are straight, some curvilinear and crescent shaped, and many of
them extremely regular, changing their trend 40° or even 50°. The curvilinear
ones convex from the disturbed sides of the zones, are generally more regular
than those which are convex towards them.

VOL. XXI. PART III. 6K

468

PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

5. Gradations in flecures.
a. In all undulated zones, the succession, starting from the most disturbed side,

b.

C.

is invariably from the folded waves to the unequally sloping or normal ones,
and from these to the equally sloping or symmetrical.

The waves grow progressively wider apart, or increase their amplitude, as
they pass from the folded to the equally sloping form.

The waves progressively flatten down as they recede from the folded side of
the belt.

d. The axis planes of the flexures of any great undulated zone all incline towards

the same quarter, that of maximum disturbance, the angle of inclination being
less the nearer the wave or plication is to that side.

6. Fractures or faults.
In undulated districts, the dislocations are of two kinds: (1.) Numerous short

ones, transverse to the strike of the axes, and shifting the strata to but a tri-
vial extent; (2.) longitudinal ones, fewer in number, of great length, and pro-
ducing often great displacement.

The longitudinal faults very generally dip towards the same quarter as the
axis planes ; indeed they are either ruptures in the axis planes of the flexures,
or in the steep or inverted sides of the waves.

This slanting of the plane of dislocation parallel with the leaning of the wave,
causes the newer or upper formations, on the inverted side, to dip under the
older or lower on the uninverted side of the flexure or the fault, for almost
always the uninverted side has been shoved forward and upward across the
inverted.

Some undulated belts are single, or have all the axis planes of the flexures
dipping to one quarter, as the Appalachians and the zone of Southern Belgium.
Others are double, or consist of two such zones, both dipping inwards towards
one central line of chief igneous disturbance, and these latter present in this
inward general leaning a fan-like structure, as in the Alps.

7. Phenomena of slaty cleavage.
a. The cleavage dip is independent of the dip of the strata; and still more re-

markably, the cleavage planes of a district are generally parallel to the axis
planes of its flexures.

. Immediately within the anticlinal and synclinal axes, the cleavage planes de-

part from their parallelism to the axis planes to dip inwards towards them in
a kind of fan-like arrangement.

. The cleavage is only present where the rocks consist of certain materials,

abounding most where they are most argillaceous and of finest texture, disap-
pearing and reappearing with changes in the composition of the strata, even
where this closely alternates.

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 469

d. In such groups of alternating cleavable and non-cleavable beds, the cleavage
planes curve from the normal dip they possess to approach to a parallelism
with the planes of separation of the strata as they near their surfaces.

e. The cleavage susceptibility is alternately greater and less in closely adjacent
parallel planes.

The ribbon structure of glaciers is probably analogous to the cleavage struc-
ture of argillaceous rocks.

8. Foliation.

In districts of crystalline, metamorphic, or gneissic strata, not much disturbed
or corrugated, the foliation generally coincides with the stratification. In
regions much corrugated the foliation, on the contrary, is often at a steep
angle to the stratification, and shows a tendency to dip, as cleavage does, paral-
lel to the axis planes of the flexures. Generally the direction of the foliation
appears to conform to that which the waves of heat metamorphosing the rocks
would take in slowly flowing through them.

9. Theories of elevation.

a. A common hypothesis of the cause of the elevation of strata is that of a wedge-
like intrusion of melted matter. But this implies a function in semifluid or fluid
matter incompatible with the dynamic properties of liquids. Some force must
have first cracked the strata before the molten rock could insert itself. Veins
and dykes tapering upward do not belong to lines of anticlinal elevation, where
geologists so frequently indicate them, but to synclinals or concave curves.

b. The kindred idea of the intrusion of igneous rocks in solid wedges separating
and lifting the crust is also at variance with sound mechanical laws. To exert
this lifting and thrusting force, the assumed wedges must have moved freely
through the fissures they fill; but we see no proofs of discontinuity between
the igneous and stratified rocks, but evidences of the closest cohesion.

c. A modified view of the wedging up of the flexible strata, conceives them to have
been simply carried up by the lifting of the igneous nucleus. Such movements
have no doubt occurred, and have served to steepen the strata leaning against
the igneous rocks, but they cannot have corrugated the strata, which would be
rather stretched than compressed by the elevation.

d. The hypothesis of a simple upward pressure at points or lines in the crust,
which does not include an explanation of the wave structure of disturbed dis-
tricts, cannot be a true theory; it must show how the pressures have shifted to
new and parallel lines, and lines constantly receding, and also show why, if
the linear pressures were simultaneous, they should not have produced a wide
general arching, rather than a series of contiguous sharp waves.

é. The hypothesis of the origin of flexures from a sinking of the ground by re-

470

PROF. H. D. ROGERS ON THE LAWS OF STRUCTURE

moval of volcanic matter beneath it, supplies no explanation of the origin of
zones of regular undulations. The sinking of any weak segment of the earth’s
crust might produce a trivial general warping, but not a belt of waves.

. The hypothesis of a simple lateral or horizontal compression, illustrated by the

folding of layers of any flexible material squeezed edgewise, and kept down by a
weight, is open to the objection that this mode of folding offers no true analogy
to the great symmetrical parallel flexures met with in nature. Flexures thus
artificially produced, show neither the forms nor the gradations characteristic
of the crust waves. A purely tangential force would cause the district within
its influence to bulge slightly upward, but not to corrugate into regular undu-
lations, and it fails to find an origin for a pressure in the direction assumed.

10. Theories of cleavage and foliation.

a.

b.

C.

d.

The prevailing notions of geologists respecting the origin of cleavage and foli-
ation are, on the one hand, that they have been produced by different intensities
of molecular crystallizing polarities, excited by heat operating in a definite
direction, on the other hand, that they have been caused by mechanical com-
pression of the strata applied perpendicularly to the cleavage and foliation
planes.

One main objection to the pressure hypothesis is, that it does not account for
the existence of planes of alternately stronger and weaker cohesion.

Another difficulty is, that it fails to explain the dependence of cleavage upon
the texture of the rock, especially its chemical nature, and particularly where
cleavable and non-cleavable strata alternate in close contact.

A third important objection exists in the dynamic difficulty, that the cleavage
is nearly parallel and constant in its dip, despite the inequalities which a
lateral pressure should undergo in its transmission through all the contortions
and various postures prevailing in the strata.

. A fourth difficulty, analogous to the last, is presented by the constancy in the

amount and direction of the elongation or creep of the cleavage rocks in the
direction of their cleavage dip; a constancy not compatible with the ever-
varying tension which the flexures and bendings of the strata would occasion.
An additional objection presents itself, in the direction of the pressure implied
by the theory, which, assuming the force to have been perpendicular to the cleay-
age planes,i mplies it to have come either from a source above the earth’s sur-
face, on the side towards which the cleavage planes are dipping, or from a source
far beneath the crust, in that quarter where invariably the cleavage and all
other symptoms of metamorphism are least abundant, or entirely wanting.
Still another important objection arises, in the contradiction exhibited be-
tween the law of gradation in the steepening of the cleavage dip demanded
by the theory, or one form of it, and the actual law of the gradation of this dip

OF THE MORE DISTURBED ZONES OF THE EARTH’S CRUST. 471

witnessed in all districts of regular crust plications. The theory represents
the cleavage dip as growing progressively steeper the nearer it 1s to the lines of
greatest igneous action, the facts in nature show that the cleavage, the folia-
tion, and the axis planes of the flexures, with which these are approximately
parallel, grow progressively steeper the farther they recede from those lines of

maximum energy.

Concluding theoretical views.
The wave-like structure of undulated belts of the earth’s crust is attributed to an

actual pulsation in the fluid matter beneath the crust, propagated in the
manner of great waves of translation from enormous ruptures occasioned by
the tension of elastic matter. The forms of the waves, the close plication of
the strata, and the permanent bracing of the flexures, are ascribed to the
combination of an undulating and a tangential movement, accompanied by an
injection of igneous veins and dykes into the rents occasioned by the bendings.

This oscillation of the crust, producing an actual floating forward of the
rocky part, has been, it is conceived, of the nature of that pulsation which all
great earthquakes produce at the present day.

11. Cleavage.
The cleavage planes having been shown to be parallel to the axis planes of the

flexures, and locally to the planes of the great faults, and these being obviously
the belts of maximum temperature in a plicated district, it 1s suggested that
both cleavage and foliation are due to the parallel transmission of planes or
waves of heat, awakening the molecular forces, and determining their direction.

(on)
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VOL. XXI. PART III.

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XXXI.—On New Forms of Marine Diatomacee, found in the Firth of Clyde and
in Loch Fine. By Witt1am Grecory, M.D., F.R.S.E., Professor of Che-
mistry. Illustrated by numerous Figures, drawn by R. K. Grevittz, LL.D.,
F.R.S.E.

(Read 19th January 1857.)

In two papers read before this Society, I have very fully described the Diato-
maceze of the Glenshira Sand, which is very remarkable both for the large number
of species found in it, which is certainly more than 320, and for the circumstances
in which it must have been deposited. There can be no doubt, from the nature of
the locality, which I have lately visited, that this bed was formed in the bottom of
the Dhu Loch, a shallow fresh-water lake, at that time extending about two miles
farther up the valley than it now does, and being at a higher level. In consequence
of a rise in the level of the land, or a fall in that of the sea (from which—that is,
from Loch Fine, the lower end of the lake is separated by a narrow and low bar-
rier, through which the waters of the lake pass to Loch Fine), the lake has long ©
ago been drained, till its upper end is nearly two miles from the point it must have
reached when the bed of sand was formed. The present level of the lake is con-
siderably lower than it was then; the precise difference I had no means of ascer-
taining, but I believe it is about 30 feet. Now, the most interesting fact about this |
lake is, that its actual level is that of half-tide, so that at low water the lake is
discharged into the sea, while at high water the tide flows upward into the lake.
Hence marine plants and animals are found in the Dhu Loch; herring, for ex-
ample, are often caught in it, and were taken while I was in the neighbourhood.
Hence also the present deposit in the lake exhibits a mixture of fresh-water and
marine Diatomaceous forms. Now, the older sand, the subject of my paper, de-
posited at a considerably higher level, also contains both marine and fresh-water
Diatoms ; and while the individuals of the two classes are both abundant, the
marine species are at least twice, perhaps thrice, as numerous as those of fresh
water.

The natural, and, I have no doubt, the true explanation of the occurrence of so
many marine forms in an inland deposit, formed in a fresh-water lake, is this:
that at the period when the sand was formed the relative levels of the Dhu Loch
and of Loch Fine were the same as now, when similar results ensue.

But as the lake was then at a higher level than now, so also must the sea
have been at a level as much above its present one. This conclusion is in ac-
cordance with those derived from the observations made on raised beaches on the

VOL. XXI. PART IV. 6M

ii

474 PROFESSOR GREGORY ON

banks of the Firth of Clyde, the level of which must always have regulated that
of Loch Fine since the present form of the coast has existed.

There was, however, a circumstance which at first tended to throw some
doubt on this conclusion, according to which the marine forms of the Glenshira
sand must have come from Loch Fine. For although the known and described ma-
rine Diatoms found in the sand occur on our coasts, yet I was struck with the fact
that out of upwards of fifty new or undescribed forms, there seemed to be no
trace in deposits from the Firth of Clyde, examined by more than one naturalist
during the progress of my investigation. The fact of these forms being unde-
scribed was prima facie evidence that they had not yet occurred on the British
coasts.

Yet it was evident that the formation of the Glenshira sand was, geologically
speaking, very recent ; so recent, indeed, that we could not suppose any number
of species to have since become extinct. I came, accordingly, to the conclusion,
that these undescribed forms must still exist in the waters of Loch Fine, or, what
is the same thing, of the Firth of Clyde. I was therefore desirous to examine
with care deposits from these waters, and this, during the past six months, |
have been enabled fully to do.

The materials which I have examined are the following :—

1. A small quantity of dirt or sand washed from some nests of Lima hians,
dredged in Lamlash Bay on the 19th of July last, in 4 fathoms, by Professor
ALLMAN. ‘This material, though, when cleaned, very scanty, proved the richest
of all.

2. Four dredgings, made by myself, with the kind assistance of the DUKE of
ARGYLL, in Loch Fine, at different points within two or three miles of Inveraray.
These were all different, and three of them were interesting. They were taken at
depths of from 14 to 18 fathoms, early in October last.

3. Three dredgings made at the same time by the Rev. Dr Barctay, in Loch
Fine, off Strachur, at depths of 15, 20, and 60 fathoms, also in October last.

4. Three materials forwarded to me in October by the Rev. Mr Mires of Glas-
gow, who was for some time on the Holy Island, in Lamlash Bay.

One of these was washed from the nests of Lima;hians, as I had reported the
richness of the former. These last were from 7 fathoms in Lamlash Bay, This
material, dredged, I think, in June, was not so rich in Diatoms as Professor ALL-
MAN’S, but yet contained many interesting forms.

The second was a coarse red sand, dredged off Invercloy, Arran, which was
rather poor.

The third was a mass of Corallina officinalis, taken with the hand, in rocky
pools, at Corregills, Arran, when the tide was low. The Corallina proved to have
been a good Diatom trap, and yielded a material, not remarkable for the number

NEW FORMS OF MARINE DIATOMACES. 475

of species, but rich in individuals, and these nearly all of interesting, rare, or new
species.

I had thus eleven different materials, no two of which were exactly alike, al-
though in all certain prevalent forms occurred. In each, on the other hand, some
forms, few or many, were peculiar, and their presence gave a distinct character.
A careful study of the whole has yielded interesting results; and these it is the
object of the present paper to state as briefly as may be consistent with ac-
curacy.

The first observation is, that these waters contain a very large proportion of all
the known and described marine forms belonging to Britain, including a good many
which have hitherto been very rare; so scarce, indeed, in some instances, that few
observers have seen them. I may specify the following as being by no means
rare, several, indeed, being abundant in these materials :—

Coscinodiscus concinuus. Pleurosigma delicatulum.
Eupodiscus crassus. oe transversale.
Ralfsi. Surirella lata.
; sculptus. Hunantidium (?) Williamsoni.
Campylodiscus Ralfsii. Amphiprora elegans.
we Horologium. Podosira Montagnei,
Navicula Hennedyi. Orthosira marina.
granulata, Préb. Grammatophora macilenta.
Lyra, Ehr. Biddulphia Baileyi.
Pleurosigma rigidum. i turgida.
obscurum.

The second observation which I made was, that, as I had anticipated, nearly
the whole of the new forms figured by me from the Glenshira sand are found
living, and generally abundant, in these waters. The following list contains the
names of such of the marine species, figured in my former papers, as I have found
in the new materials :—

Cocconeis distans. Navicula didyma 6.

; costata, see crassa.
Eupodiseus Ralfsii; also var. 6, sparsus. Pinnularia Pandura.
Campylodiscus simulans. wie longa.
Surirella fastuosa, very large. <a inflexa.
Amphiprora recta. Amphora Arcus.

lepidoptera. --. crassa.
Navicula rhombica. »tryou Clegans.
maxima. ... _ plicata.
angulosa, and var. f. ... obtusa,
humerosa. i Grevilliana.
latissima. ... rectangularis.
clavata. ... lineata,
splendida. Synedra undulata.
incurvata. Tryblionella constricta.
didyma, var. y, costate a apiculata.

I think we can hardly doubt that all the new Glenshira marine forms will
ultimately be found in the neighbouring waters.

476 PROFESSOR GREGORY ON

Before going farther, I have to remark, that two of the forms in the first list
above given, namely, Canpylodiscus Horologium and Himantidium Williamsoni,
which had only been found by Professor WiLL1amson, who detected them both in a
dredging made by Mr Bartz on the coast of Skye, in which they were very scarce
indeed, have occurred abundantly, the former in one of the Loch Fine dredgings,
and sparingly in some of the others, the latter in another of them, and, though
less abundantly, yet frequent in nearly all the Clyde materials. We shall see
that Himantidium Williamsoni, which Professor Smiru had referred doubtfully to
that genus, not having been able to see more than the front view of it, is really no
Himantidium ; the side view, which is very abundant in one of my dredgings, hay-
ing characters quite incompatible with the genus Himantidium. On this account,
I shall refer to it among the new forms which I have to mention. I have found it
a matter of very great difficulty, if not impossible, to refer it to any of the genera
in SmitrH’s Synopsis. I may here add, that Synedra undulata, which I had recog-
nised in the Glenshira sand, but which had never occurred entire in that de-
posit, is frequent in the first material from Lamlash Bay (Professor ALLMAN’s),
where it occurs quite entire in more than half of those I have seen, and, as I had
concluded, from the imperfect specimens I had seen, attains a length of from
0015 to about 0:02, which, for a Diatom, is gigantic. I had previously noticed a
fragment of it in arecent gathering made by Professor Smiru, and he had himself
subsequently found it frequent in Cork harbour. ‘The first observer, however,
was Professor Baitry, of West Point, New York, who had found it still larger
on the American coast, which I was not aware of till long after my observations
on the Glenshira sand were made.

The third observation I shall here record is, that in these dredgings I found,

in sufficient abundance, several very curious forms which had occurred in the —

Glenshira sand; but the description and figuring of which I had postponed, be-
cause either they were so scarce that I could not obtain good specimens, or,
being only found in a fragmentary, detached, or imperfect state, I was quite at a
loss to determine their true nature and position. I think I may say that in every
such case I have been enabled, by the study of the new materials, to understand
the nature and structure of these obscure or doubtful forms, and to establish
them as new and distinct species. I have also been enabled to understand better
several of the forms which were figured in my former papers, and to correct
some errors which had crept into these.

I need not here give a list of the forms just alluded to, as they will be in-
cluded in that of the new forms to be described. In that list, I shall mark them
with a G, to indicate that they were first noticed in the Glenshira sand.

Lastly, in the new materials I have found a large number of entirely new and
undescribed species, which I shall now proceed to enumerate. I may here men-
tion, that although a good many fresh-water forms do occur in these dredgings,

ON De ee

NEW FORMS OF MARINE DIATOMACES. 477

as must, indeed, be the case, since the Clyde and all its tributaries bring down
such forms, yet the new forms in question appear to be all of marine origin.
They are, in general, much too abundant to have been derived from any other
quarter, whereas the fresh-water forms among them are much scattered. It
is proper also to state, that although all these forms are, to the best of my
belief, new to Britain, yet a few of them have been described by EHRENBERG in
some of his numerous works, and also by De Bresisson. The great majority,
however, have not anywhere been figured; not, at least, in any ‘works accessible
to me.

_ As the new forms belong to a very few genera, it will be convenient to arrange
them in groups. Those J shall adopt are as follow :—

I. Naviculoid Forms.
II. Cocconeides.
Ill. Filamentous Forms.
IV. Discs, including Campylodisci.
V. Amphiproree.
‘A. Simple.
VI. Amphoree. i Ganey!

VII. Miscellaneous.

GROUP I.

Navicutoip Forms.

These, as is usual in all gatherings, are numerous. Including two or three
varieties of species already known, those which I have recognised as new are
the following :—

1. Navicula minor, n. sp. 10. Navicula spectabilis, n. sp.

2. Cluthensis, n. sp. Mls ... preetexta, Ehr.

3. inconspicua, n. sp. 12. ... Bombus, Ehr.

4, brevis, n. sp. 13, gig © iyta,. hn.

5 Claviculus, n. sp. 14, ... Lyra, Ehr. var. ®, abrupta.

6 ... Musca, n. sp. 15, ... smith, var. 6, fusca.

16 ... rectangulata, n. sp. 16. ... Smithii, var. y, nitescens.

8 ... nebulosa, n. sp. iis ... Smithii, var. 6, suborbicularis,
9. ... Barclayana, n. sp. 18. ... . maxima, Greg.

1. Navicula minor, n. sp. PI. TX., fig. 1. Form rectangular in the middle, acu-
minate at the ends, which are acute. Length from 0:0012” to 0:0025”; breadth
00004” to 0-:0008”. Strize fine, inclined near the ends, not reaching the median
line, 36 to 40 in 0-001". The whole form has a delicate aspect.

This little form, represented in fig. 1, occurs in two or three of the Loch Fine
dredgings, in one of which it is sufficiently frequent.

VOL. XXI. PART IV. GN

478 PROFESSOR GREGORY ON

2. Navicula Cluthensis,* n. sp. Pl. IX., fig. 2. Form oval, rather broad. Me-
dian line broader at the centre, narrower at the apices. Central nodule definite,
large; terminal nodules smaller. Length 0:0013” to 0:0016"; breadth about
0-001”. Strize conspicuous, clear, and sharp, inclined slightly in the middle,
a near the ends; about 20 in 0:001”.

Fig. 2 represents this form, which occurs in Professor ALLMAN’s dredging from
Lamlash Bay, and though not abundant, is yet frequent enough for all practical
purposes. It is very uniform in its characters, and though the description above
given may not appear very characteristic, yet I know of no form with which this
one can be confounded. Its aspect is so peculiar that it is instantly recognised.

3. Navicula (2) inconspicua, n. sp. Pl. IX., fig. 3. Form linear, rather narrow,
with rounded ends. Median line strong, complex, interrupted in the middle.
Nodule definite. Aspect of valve hyaline. Striation so fine that it has not yet
been resolved; and at all events it cannot be visible under a power of 400.
Length 0:002” to 0:0032; breadth about 0:00035.”

This little form occurs both in Lamlash Bay and in Loch Fine. I do not feel
quite sure that it is a Navicula, as it may possibly belong to a filamentous species ;
it may be, for example, a Diadesmis; or it may prove to be a Schizonema. This
can only be ascertained by observations on examples in the living state.

4. Navicula brevis, n. sp. Pl. IX., fig. 4. Form nearly elliptical in the middle;
broad, short ; contracted to short, produced, obtuse extremities. Length about
0:0023"; greatest breadth 0°0013". Strize fine, about 35 in 0:001’; very slightly
inclined, not reaching the median line, and at the centre leaving a large, round,
blank spot,within which the two halves of the median line end in small rounded
expansions. Central nodule indefinite; terminal nodules definite.

This form is easily recognised by its short, squat shape, and is distinguished
from NV. semen, which it resembles in form, by its much finer striation. It occurs
in Lamlash Bay, and is not very scarce in Professor ALLMAN’s dredging from that
locality.

5. Navicula Claviculus,n.sp. Pl. IX., figs. 5,506, and 5c. Form of valve linear,
narrow, with one central and two terminal expansions, separated only by two
constrictions. The terminal expansions are much elongated, oval at the extre-
mities, and rather broader than the central expansion. Central nodule definite.
Length 0:0015” to 0:002"; greatest breadth 0:0002” to 0:0003". On the S$.V.,
figs. 5 and 50, the central expansion is unstriated. Strice on the rest of the valve
transverse, sharp, not quite reaching the median line; about 32 in 0:001”. The
F.V., fig. 5 c, is rectangular, with slightly expanded and bevelled angles, and exhi-
bits the same absence of striz from the middle part.; ‘The strize are seen to a

* From Clutha, the Clyde.

t Figs. 5 b and 5 ¢ are magnified 800 diameters, to bring out the details. Fig. 5 is magnified
only 400 times, and is below the average Size.

NEW FORMS OF MARINE DIATOMACES. 479

certain extent on the F.V., but most towards the extremities, indicating that the
S.V. is more convex near the ends than in the middle. I have named this form
from its resemblance to a small two-headed club.

It occurs only in one of the Loch Fine dredgings, in which, though far from
frequent, I have been able to examine many more specimens than are required to
ascertain the characters of the dead form. I observe that it often occurs in pairs,
as well as solitary, so that it may perhaps belong to a filamentous genus, such as
Diadesmis. But as I cannot be sure of this, without seeing the living or growing
form, I refer it, for the present, to Navicula.

6. Navicula Musca, n. sp. Pl. IX., fig. 6. Form of valve deeply constricted in
the middle, broadest at a point near the middle on each side of it, and almost
triangular thence to the acute apices. Length 0-002’; greatest breadth 0-0011’ ;
breadth at middle 0:00075”. Striation confined to a marginal band, which is
rather broad, and nearly of uniform width, except at the apices. Median line
sharp; central nodule definite. Strize coarse, 18 in 0-001”; distant, moniliform.
Aspect of the valve transparent.

The form of this very pretty species is allied to that of V. didyma and the other
panduriform Navicule, which are so frequent in marine gatherings. Even its form,
however, is peculiar, and it is at once distinguished from all the others by its mar- —
ginal striation. It so much resembles in shape the body of a bee or wasp, that [
should have named it Apis or Vespa, had not these names been already appro-
priated to other species by EnreNnBERG. I have chosen, therefore, the specific name
Musca, as the form is also that of various large flies. It occurs in the same Loch
Fine gathering, as Nos. 1, 3, and 5; a gathering which, though very scanty and very
stony, has proved singularly rich in undescribed forms, especially of Amphoree,
as we shall see farther on. This dredging was a very coarse sand, which, after
boiling with acid, I was on the point of rejecting as useless, when I observed a
very trifling cloud of finer matter. This, though full of mica, supplied a remark-
able proportion of new species; so much so, that I believe it contained as many
of these as of known species; and of the undescribed forms found in it, a majo-
rity have occurred in it alone. I mention these facts, in order to show that every
dredging, however unpromising, in such localities as Loch Fine and the Clyde,
ought to be closely examined. This one was most unpromising; yet it turned
out not only rich in new species, but very different from the other dredgings made
in the same waters.

7. Navicula rectangulata,n.sp. P1.1X., fig. 7. Form of S.V. rectangular, the
extremities being rounded; rather narrow. Length from 0003” to 0-004’;
breadth about 0:0006” to 0:0008”. Striation highly radiate, there being three
centres of radiation on each side—one in the middle, and one at eachend. Strize
soft, not very fine, subdistant; about 22 in 0°001”, not quite reaching the median

480 PROFESSOR GREGORY ON

line, and leaving a very small, round, blank space in the centre. Central nodule
indefinite. The F.V. has not yet been recognised.

This form is remarkable for the shape of the S.V., which is that usually found
in the F.V. It occurs rather sparingly in Professor ALLMAn’s dredging from Lam-
lash Bay, which, of all the dredgings, is the richest in species, whether known or
undescribed.

8. Navicula nebulosa, n. sp. Pl. 1X., fig. 8. Form oval, broad; generally with
a slight tendency to angularity in the middle, and also a tendency to acumina-
tion at the apices. Length from 0:0025" to 0:0035"; breadth 0:0013” to 0:0016".
Median line sharp, ending in two elongated expansions at the centre, which do
not meet. Nodlue indefinite. On each side of, and close to, the median line, is
a narrow rectangular band of striation, interrupted at the nodule. At the margin
is a somewhat broader, but still narrow, striated band, almost exactly of uniform
width throughout. Strize 34 to 36 in 0°001". Aspect of valve hazy and indistinct.
Striated portions pale blue under the half-inch objective. This form is allied to WV.
Hennedyi, figured in my second paper on the Glenshira sand (see 7rans. Mic. Soc.,
vol. iv., pl. v., fig. 3.) But I have found it necessary to separate it from that spe-
cies, in consequence of its very different aspect. V. nebulosa is a smaller form than
N. Hennedyi, the one here figured being an unusually large one. It is also much
more finely striated; and, above all, it has invariably that peculiar indistinctness
of aspect from which I have named it; whereas WV. Hennedyi, even when of a
smaller size, as we sometimes find it, is always remarkable for the sharpness of
its markings. The tendency to angularity generally seen in WV. nebulosa is never
found in NV. Hennedyi. Lastly, the striation of the former is so much finer, that
the striated parts, seen under a low power, have a very pale bluish tinge never
seen in the latter. When the two forms are seen in the same field of view, as often
happens in Professor ALLMAN’s dredging from Lamlash Bay, and even when JW.
Hennedyi is the smaller, though it is generally much larger, the difference between
them is very striking. I might have considered WV. nebulosa as a variety of NV. Hen-
nedyi, but that I have found both forms exceedingly uniform in their characters,
and have not been able to observe any tendency to transition from one to the other.
N. nebulosa is frequent in the Lamlash Bay dredging just mentioned, in which NV.
Hennedyi also occurs ; but elsewhere I have hardly ever seen the present species.

9. Navicula Barclayana, n. sp. P1.IX., fig.9. Form an elongated oval, some-
what suddenly contracted to acute extremities, terminated by small round api-
culi. Median line narrow, ending at the middle in two small expansions. No-
dule indefinite. Length 0-004” to 0:0045"; breadth 0-001” to 00-0012”. Striz
about 38 in 0:001”, somewhat inclined, sharp, minutely moniliform, confined toa
marginal band, which is rather narrow, and of uniform width except near the
apices, where it becomes narrower.

This is a fine conspicuous form, and occurs not unfrequently in the same Loch

NEW FORMS OF MARINE DIATOMACEZ. 481

Fine dredging, with NV. Claviculus, N. Musca, &c. 1 have also seen it, though
much more sparingly, in some of the other dredgings, both from Loch Fine and
Lamlash Bay.

10. Navicula spectabilis,n. sp. Pl. IX., fig. 10. Form elliptic-lanceolate, very
broad; ends subacute or acute. Length from 0:003” to 0:005”; breadth from
0:0023” to 0:0032”. Median line sharp, having close to it on each side a narrow
striated band, interrupted at the middle. Central nodule large, indefinite. There
is a marginal band of striation, which is very broad in the middle, where it pro-
jects inwards to an obtuse point, and very narrow at the apices. Strize coarse,
moniliform, about 22 in 0-001". The blank spaces between the marginal and
central bands are very broad; and this part of the valve is so thick and strong,
that in fractured specimens we never find it broken across, but we often see the
entire blanks, united by the central nodule, which is elongated laterally, separated
from all the striated parts, forming a singular object.

This form is allied to NV. Lyra, Ebr., and also to V. Hennedyi. I consider it,
however, quite distinct from either. It occurs frequently in Lamlash Bay; but I
have not yet seen it elsewhere. The form and width of the marginal band dis-
tinguish it from WY. Hennedyi, while the broad blank spaces distinguish it from —
N. Lyra, in which, as we shall see, these spaces are linear. Besides this, V. Lyra
very often occurs with produced ends, and never has the peculiar form of N.
spectabilis. The latter never occurs with produced ends. Moreover, under a low
power, J. spectabilis has a bright brown colour, in the striated parts, not observed
in WV. Lyra. Lastly, I find this form remarkably uniform and constant in its

- characters. It is very conspicuous, and generally larger than N. Lyra.

11. Navicula pretecta=Pinnularia pretecta, Ehr. PI. IX., fig. 11. Form a
pure and broad oval. Length from 0-004” to 0°005"; breadth 0:0025” to 0-003”.
Median line sharp, the central extremities ending in large, rounded expansions,
which are bent to the same side. Central nodule indefinite, extending trans-
versely. On each side of, and close to the median line, a narrow linear band of
very coarse and coarsely moniliform striz. At the margin of the valve is a rather
broad band of striz, exactly like those of the central bands. This marginal band
is of uniform width till near the apices, where it gradually becomes narrow.
Striz 8 to 10 in 0-001". The broad intermediate space between the marginal and
central bands is not blank, as in V. Hennedyi, but is irregularly dotted or stippled
with round granules, precisely the same as those of the striz. Towards the centre,
and near the ends, the median striated bands pass gradually into the sparsely
dotted space. Between these points the median bands end more abruptly. The
scattered granules are consequently most thickly set round the nodule and near
the apices. The granules are so large, that there are not more than five in each
of the longest of the marginal striz.

This conspicuous and beautiful species has been figured by EHRENBERG, as

VOL. XXI. PART IV, 60

482 PROFESSOR GREGORY ON

occurring in the Clay Marl of gina, a bed belonging either to the Chalk forma-
tion or to the oldest Eocene strata. It seems to be very scarce there, for EHRENBERG
has figured an imperfect specimen. I found it first rather sparingly in Professor
Autman’s Lamlash Bay dredging; and, since then, still more sparingly in Mr
Mixes’s, from the same locality, as well as in several of my Loch Fine dredgings.
It is obviously a member of the same group as V. Hennedyi, N. nebulosa, and
others, with marginal and central striated bands. It is distinguished by its size,
by the remarkable coarseness of its striation, and by the peculiarity that granules,
such as form the strize, are scattered over the unstriated space, without regu-
larity. I have been informed that a form of V. Hennedyi occurs, with a similar
character, but this I have not seen. I presume it will be easily known by its
much finer striation, and its smaller size. Though this species is hitherto scarce,
I have been able to examine a large number of examples, and also to supply
various correspondents with specimens.

I avail myself of this opportunity to point out, that we have here an excellent
example of the occurrence, in the recent state, in our seas, of a species hitherto
known only as a fossil one. But as the Clay Marl of Agina is the oldest deposit
in which Diatoms have been detected with certainty, we have evidence that a
species which is among the oldest of known Diatoms still exists. Nor is this by
any means an unusual occurrence. In Enrenzere’s plate of the microscopic
forms of this Eocene clay marl (Eocene at least, if not Cretaceous), he figures
many other forms, all of marine origin ; and all, or nearly all, of which are still
living species. Indeed, I have seen upwards of three-fourths of these Diatoms in
the dredgings described in this paper. Among these are Actinocyclus undulatus,
Coscinodiscus radiatus, Pyxidicula cruciata, Navicula pretexta, N. Bombus, and
many other frequent forms. I feel. assured that every form of Diatom found in
that Clay Marl, still lives in the present seas. And if this be the case with the
oldest Diatomareous deposit, it is no less likely to hold good of such as are of
later date. In the great bed of Richmond, Virginia, which is marine, and said
to be of the Miocene period, perhaps the most frequent form is Orthosira marina,
Sm. (olim Melosira sulcata, Kiitz.); a form which I find, as already mentioned,
very abundant in Lamlash Bay. In the same deposit occurs Coscinodiscus cen-
tralis, Ehr., a splendid disc, to be described farther on, as occurring in the Clyde;
and I might multiply similar examples almost ad injinitum.

Here the question naturally presents itself, Are there any extinct species of
Diatoms? Strange as it may seem, when compared with what is found to occur
in organisms of other and higher classes, I believe that this question ought to be
answered in the negative.

In the earlier works of EnRENBERG, we frequently meet with species, and even
with large groups of species, or almost genera, which are stated to be “ fossil
only,” and which were believed to be extinct. Such forms are Campylodiscus

NEW FORMS OF MARINE DIATOMACE. 483

elypeus, found in the polishing slates of Bohemia, and the whole series of den-
- tate Eunotie, found so abundantly in the Lapland Bergmehls.

But the progress of observation has shown that these forms are still in exist-
ence. C. clypeus has recently been found in British waters ; and in America, and
elsewhere, the dentate Eunotie, such as &. Diadema, E. heptodon, E. octodon,
E. Serra, and others, have been found recent. I have myself often found, during
the last two years, H. iriodon, a form long regarded as extinct, in many of our
streams, although scattered. But last summer I detected it as the predominant
form in a gathering made by Professor BaLrour, in a small stream on a hill in
Arran, not far from Lamlash.

I conclude, therefore, that our knowledge of the existing species of Diatoms
is yet far too limited to allow us to say that any fossil species no longer exists.
In this very paper, I make known the actual existence of several species, hitherto
supposed to be exclusively fossil, and every day adds to the number of existing
forms, while it diminishes that of those conjectured to be extinct, few of which
are now left. Surely, when one or two localities yield so many undescribed forms
as I have here the honour to lay before the Society, we are not entitled to con-
clude that any form is extinct, because hitherto it has only been met with in the —
fossil state. In the present state of our knowledge, it is far more probable, that
we shall ultimately find, as I have done in the case of NV. pretexta, that the sup-—
posed extinct species are all still in existence.

But, it may be asked, How is it that you suppose no species of Diatoms to have
become extinct, when, in almost every other class, the extinct species far out-
number the existing ones? In answer, I would observe, first, that we have
no undoubted evidence of the existence of Diatoms earlier than the Clay Marl
above named, which is either Eocene, or a member of the latest Chalk deposits.
Now, if it be Eocene, then we know that that formation contains, even among
fishes, a certain proportion of existing species. This proves that the condition of
the Eocene period did not differ nearly so much from the present conditions as
those of earlier deposits must have done; those, for example of the Carboniferous
series, of the Old Red Sandstone, or of the Silurian strata.

Secondly, the size of Diatoms is so very minute, and their structure so exceed-
ingly simple, that they must be little, if at all, affected, even by very considerable
climatic variations. Of this, indeed, we have ample evidence, so far at least as
concerns existing differences of climate. If we consult the plates of EnrENBERG’s
Microgeology, we shall see that the existing species of Diatoms found in the most
distant and different parts of the world, in the Arctic and Antarctic Seas, in the
tropical zone, and in our own temperate regions, are, for the most part, absolutely
identical. There are, no doubt, local differences; but these, as is shown in this
paper, may be very great in almost contiguous localities. On the other hand,
having examined the diatoms in a large number of American and other exotic

484 PROFESSOR GREGORY ON

soils, I have always found a very great majority of common British species. As
an example, I may specify two soils particularly rich in Diatoms; one from the
Sandwich Islands, the other from Lebanon. The former was quite like an ordi-
nary fresh-water gathering, the latter resembled a poorer material. In both, I
have great doubts whether all the numerous species are not identical with our
own. Some few of the species, indeed, are not to be found in Smiru’s Synopsis;
but most of these have been described by others, or by myself, as British forms,
since that work appeared.

So far, therefore, as the greatest actual differences of climate are concerned,
Diatoms are apparently not affected ; as in the cases just mentioned, it is impos-
sible to distinguish the exotic specimens from British ones.

If, therefore, Diatoms did not exist earlier than the Eocene period, it is quite
conceivable that none of them may have become extinct.

I have already stated that the Clay Marl of gina is supposed by some to be-
long to the formation next below the Eocene, that is, to the latest Cretaceous beds ;
but that there is no satisfactory evidence of Diatoms in any earlier formation. If we
admit the Xanthidia to be Diatoms, these forms are known to occur in chalk
flints. But the Xanthidia are not usually regarded as Diatoms, and I have not
seen, either in flint or in chalk, any admitted or recognised Diatoms.

EnRENBERG figures many microscopic forms from the Chalk and older strata,
some even from the Silurian Greensand. But these older forms, at least so far
as are shown in the Microgeology, are not Diatoms, but either the siliceous Poly-
cystineee, or the calcareous Polythalamia, or, finally, sponge spicules.

I admit that Diatoms may have existed in the Chalk or earlier, and that, by
a slow chemical change, they may have been destroyed, so that their form is lost,
the siliceous material alone remaining, whether alone or in combination. We may
even suppose that flint has been formed in part from the shells of Diatoms which
lived along with the Foraminifera or Polythalamia of that period. But these
are mere conjectures, and till Diatoms are found in the older strata, it must re-
main doubtful whether they existed previous to the Eocene period.

The Chalk or Marl of Meudon, near Paris, and that of Caltanisetta, in Sicily,
exhibit a mixture of microscopic forms, calcareous and siliceous, including Dia-
toms. Here Diatomaceous shells, in contact with excess of calcareous matter,
have remained unaltered; and if the Chalk of the true Cretaceous period had ori-
ginally contained Diatoms, it seems probable that they would have been found as
little altered as those of the newer beds just alluded to.

On the whole, then, it is probable that the continued existence of all, or nearly
all, the known fossil species of Diatoms is the result, first, of their comparatively
late introduction, and secondly, of their small susceptibility to climatic changes,
arising from their minute size and very simple structure.

12. Navicula Bombus, Ehr. PI. IX., fig. 12. Form much constricted in the

NEW FORMS OF DIATOMACE. 485

middle, the two halves broad and rounded, with subacute extremities. Median
line broad; central nodule square, definite. Length about 0.0045"; greatest
breadth 0:0018". Striation coarse, strongly moniliform, not reaching the median
line, but leaving a narrow blank space on each side of it. Strize about 18 in
0:001, much inclined near the apices.

This form, which JI had found frequent in the Glenshira sand, is also fre-
quent in the new dredgings. It is regarded by many as a variety of WV. didyma,
and by others as a variety of V. Crabro. Iam disposed to consider it a distinct
species, on account of its peculiar and very constant form, and also because it has
a decided light-brown colour in balsam, under a low power, which NV. didyma has:
not. It is much largerthan V. didyma. As to N. Crabro, the moniliform structure
in it is always obscure, and the form is also different. I cannot perceive that J.
Bombus passes into either of these species by intermediate forms. But whatever
be the ultimate decision on this point, I give it here.as the form called by Euren-
BERG WV. Bombus ; which, be it species or variety, is at all events conspicuous, and
very constant in its characters.

In my last paper on the Glenshira sand, I have figured several Navicule and
Pinnulariz of the panduriform group, and I[ have pointed out that this remark-
able group requires thorough investigation. In order to contribute towards this ©
end, I have figured the present form, as well as NV. Musca, a new member of the
same group; and I shall describe, farther on, another, namely a remarkable form
of Pinnuwlaria Pandura, Bréb. .

13. Navicula Lyra, Ebr. P1. IX., fig. 138 and136. Form oblong-elliptic, broad ;
often contracted to short produced extremities. Length from 0:002” to 0:0045’ ;
breadth 0:0007” to 0:0018”. Median line fine, interrupted by a large indefinite no-
dule, extending transversely. On each side of, and in contact with, the median
line, is a linear, somewhat broad, striated band, and this is separated from the very
broad, marginal, striated band by a narrow linear blank space. These linear blank
spaces are, in each half, united by their base to the extremities of the nodular
blank. They bend outwards from this point, then inwards, and finally again
outwards at their extremities, thus forming, in the entire valve, two lyrate shapes
united by their bases. Hence the name. The lyrate character is often much
more decided than in the specimens figured. The extremities of these lyrate
blanks generally reach the margin of the valve near its apices, but sometimes
fall short of this, as in the figure. Strize about 22 or 24 in 0:001", somewhat in-
clined near the apices.

This species, which occurs in the Glenshira sand, and is scattered through all
the dredgings here mentioned, has been described, though not as I have described
it above, in the 2d volume of Professor SmitH’s Synopsis. Professor SmirH seems
to have seen only a variety, to be presently mentioned, which does not possess the
lyrate character, and has therefore omitted that character. He refers to a figure

VOL. XXI. PART IV. 6 P

486 PROFESSOR GREGORY ON

in vol. i. (fig. 152 @*) given as WN. elliptica, which is not lyrate; but the name
given by EHRENBERG proves that he regarded the lyrate character as a principal
one. I have therefore figured it, in order to show that it occurs in Britain as
EHRENBERG described it.

14. Navicula Lyra, Ehr., var. 8, abrupta. P1. IX., figs. 14 and 146. Form
usually oval, more or less elongated ; sometimes linear in the middle, broad, with
parallel sides, and obtusely acuminate at the extremities. I have hardly ever seen
it with contracted and produced ends, as is so often observed in NV. Lyra. Size and
striation as in V. Lyra, but the blank spaces, which are linear, as in that species,
instead of being recurved at the ends, or lyrate, bend inwards at the ends, so as
to form two narrow ellipses meeting in the central nodule. These linear blanks
in this variety stop abruptly at some distance from the terminal margin of
the valve, which, in V. Lyra, they often, though not always, reach.

This form, which is frequent in the Glenshira sand, as well as in the dredg-
ings, is that already referred to as having been figured in vol. i. of the Synopsis
(fig. 152 a*), as N. elliptica, and since referred to as N. Lyra, in vol. ii.

I figure it here, both that it may be compared with the NV. Lyra of EHRENBERG,
and that it may be contrasted with WV. spectabilis (fig. 10), which is supposed by
some to be a form of NV. Lyra. The form of the latter, and the fact that the
blank spaces in it are not linear, but broad, and reach the margin, all which cha-
racters are very constant; to which may be added the rich brown colour of WN.
spectabilis in balsam, under a low power, seem to me to be sufficient to distinguish
it from N. Lyra. The reader is requested to compare fig. 10 with figs. 13, 13 4,
14, and 1406. The latter forms are colourless in balsam.

15. Navicula Smithii, var. 6, fusca. PI. 1X., fig. 15. Form an elongated oval,
broad, with rounded ends. Length from 0-003” to 00-0063”, and even more;
greatest breadth from 0:0014” to 0:0028". Median line narrow at the terminal
nodules, which are a little within the apices; broad, and formed of three parts,
all ending in expansions, on each side of the central nodule. Nodule large, broad,
indefinite. Striation very coarse, and coarsely moniliform, not reaching the me-
dian line, but leaving on each side of it a narrow blank line, terminating in the
angles of the nodular blank. The whole spaces, taken together, form two very
acute long triangles, base to base Strize about 10 in 0-001". At about one-third
of the distance from the median blank lines to the margin, the striz are traversed
by a strong, dark line, which is often, as in the figure, nearly rhombic, but is
generally curved, though very slightly. This line is caused by a ridge or eleva-
tion of the valve, and is very conspicuous. Valve thick, and highly convex, of a
strong brown colour, in balsam, under the 3 or 2 of an inch objectives.

This form, which is very conspicuous, occurs, like the two preceding, both in
the Glenshira sand and in the dredgings; and in that of Professor Attman from
Lamlash Bay and one from Loch Fine, it is frequent. I give it as a variety of WN.

NEW FORMS OF MARINE DIATOMACEZ. 487

Smithii (olim N. el&ptica Sm.), because I have always understood the typical JN.
Smithii to be a form which is very frequent in the Glenshira sand, and occurs also
in the new materials. It is ofa short, broad, inelegant, oval shape, flat, colourless,
and much less coarsely striated. Neither does it exhibit the longitudinal ridge so
distinctly. It may be, that the present form, JV. fusca, is the typical one, and the
other a variety of it; but in my experience I have only seen WV. fusca in the
gatherings above named, while I observe NV. Smithii in every marine gathering.

16. Navicula Smithii, var. y, nitescens. P1.1., fig. 16. Form lanceolate, tend-
ing to rhombic, with obtuse ends. Median line straight, nodule definite. Length
from 0-002” to 0:0035"; breadth from 0:0009” to 0:0014”. Strize about 16 in
0:001”, considerably inclined, obscurely moniliform, and of a shining aspect.
They are traversed by a ridge, which is about half-way from the margin to the
median line, and has an outline more rhombic than that of the valve.

This form occurs both in Lamlash Bay and in Loch Fine, and is not at all
rare in some of the dredgings. It is conspicuous, from its elegant form and shin-
ing aspect. It is quite colourless under a low power. I have given it as a variety
of NV. Smithii, from a desire to avoid unnecessary multiplication of species. But I
am inclined to regard it as distinct from that species, from its peculiar form, its .
smaller size, the character of the nodule and median line, and its bright white
aspect; all of which characters are very constant.

17. Navicula Smithir, var. 3, suborbicularis. Pl. (X., fig. 17. Form a short,
broad oval, or suborbicular. Length 0-002” to 0:0026”; breadth 0-0013” to
0:0018”. Median line bounded by white lines, curving inwards both to the apices
and to the indefinite nodule. Striation conspicuous, much inclined. Strize 16 or 18
in 0-001’, moniliform. There is a ridge, as in the two preceding forms, traversing
the strisze, and when the strize near the margin are in focus, those between the
ridge and the median line are very faint.

This form occurs in Lamlash Bay, and is also tolerably frequent in one Loch
Fine gathering, in which the preceding form is not found. Its small size, nearly
round form, and peculiar median line, with the slightly-marked ridge, compared
to that in the two preceding forms, seem to point it out as distinct; especially as
it is very constant in its characters. But, for the reasons already stated, I give
it asa variety. Itis at least a form to be noticed, and to be considered with the
others with a view to a more accurate determination of species than has yet been
possible, but which, in the progress of observation, we may hope to attain.

18. Navicula maxima, Greg. Pl. 1X., figs. 18, and 186. Form of 8.V. linear,
rather narrow, with obtuse ends. Length from 0002” to 0:008”; breadth of S.V.
from 00-0025’ to 000011"; of F.V. in the larger specimens, 0:0009” in the middle,
0:00115” at the ends. Striz fine, but distinct, about 52 in 0-091", parallel, not
quite reaching the median line, from which, at the centre, they retire, leaving a
pretty large round space. F.V. rectangular but narrowest at the middle, and

488 PROFESSOR GREGORY ON

slightly expanded at the ends, the angles being bevelled. From the opposite
ends the margin inclines very slightly, but visibly, to the middle. Nodules very
conspicuous on the F.V., in which the striation also extends, on each side, to
rather more than {th of the width of the frustule, which arises from the convexity
of the 8.V.

I first described this species in my first paper on the Glenshira sand, in which
the figure was not characteristic. I figured it again in the second paper; giving,
however, a shorter, broader, and constricted form as the type, and the present
one as a variety. I have since found it frequent in all the dredgings, but espe-
cially abundant in one from Loch Fine, and am now satisfied that the linear form
is typical and the broad constricted form a variety. I give the peculiar and
characteristic F.V. for the first time. The S.V. in fig. 18 0, is that of a broad in-
dividual of the linear type. It is generally narrower, and often even no more
than half this width. The shortest specimens are often still narrower. The
broad, incurved form, at first regarded as the type, is very scarce in the dredgings,
compared to the linear form.

This form has been supposed to be identical with WV. firma, Kitz, var. 8; but
its marine habitat at once negatives this supposition ; and, besides, its aspect and
colour are quite different. NV. firma is brown, while V. maxima is of a pale straw-
colour. The striation in JV. firma is coarser and more conspicuous; and, lastly,
N. firma is broader, has acute extremities, and yields several marked varieties,
such as ExrenBerc’s WV. dilatata and N. Amphigomphus ; while the only observable
variety of V. maxima is the shorter, broader, incurved one, represented in fig. 2
of my second paper on the Glenshira sand.

, 19. Pinnularia (¢) subtilis, n. sp. Pl. IX., fig. 19. Form linear rhombic, very

narrow, with elongated apices. Length about 00035"; greatest breadth about
000025”. Nodule definite. Costze about 28 or 30 in 0-001"; transverse, slightly
inclined towards the apices.

This form occurs in Lamlash Bay. I do not feel quite sure about its genus.
It may be a Navicula. The whole form is delicate and translucent, and it is far
from conspicuous.

20. Pinnularia rostellata,n. sp. Pl. TX., fig. 20. Form linear, broad, with
acuminate ends, terminating in short, acute apiculi. Length from 0-002” to
00027"; breadth about 00007". Central nodule definite. Costee strong, subdis-
tant, inclined near the ends, reaching the median line, about 14 in 0-001”.

This pretty form occurs both in Lamlash Bay and in Loch Fine. It is not
frequent, but I have been able to examine a considerable number of specimens,
which are quite constant in their character.

21. Pinnularia Allmaniana. P|. IX., fig. 21. Form elliptic-lanceolate, broad,
extremities subacute. Valve highly convex on one side, concave on the other.
Length from 0:0016" to 0:0026” ; breadth from 0:001” to 0:0014”. Costee appa-

NEW FORMS OF MARINE DIATOMACE. 489

rently marginal, strong, about 20 in 0:001", giving the appearance of a narrow
marginal band of very strong costze. Within this band, however, the valve, on
close inspection, is found to be marked with similar but much fainter coste
nearly to the median line. The valve appears to be thicker near the margin than
in the middle, and this perhaps is the reason why the coste are so strong and
conspicuous there.

This form is frequent in Professor AttMAn’s dredging from Lamlash Bay, and
it occurs also in Loch Fine. I have named it after Professor ALLMAN, to whom I
am indebted for this dredging, the richest of all those here described.

22. Pinnularia Pandura= Navicula Pandura, Bréb., var. B, elongata. Pl. IX.,
fig. 22. Form deeply constricted in the middle, with elongated sub-triangular
ends, and obtuse apices. Length 0:0075” or more; greatest breadth 0:002”, breadth
at constriction 0°0014". Median line sharply defined, broader at the centre than
at the ends; nodule square, definite. On each side of the median line, and a
little way from it, there is on each side a line or ridge, apparently formed of large
granules, but probably only apparently so, from the sudden and sharp elevation
of the ends of the costze. Costze, from this point to the margin, perfectly entire
and glassy, like those of P. alpina. Valve thick, costz 10 or 11 in 0:001”, some-
what inclined near the apices.

This seems to be a variety of De Brepisson’s Navicula Pandura, which I have
represented in the second paper on the Glenshira sand, in figs. 11, 12, and 12*.
But as Dr Bresisson himself describes the costze as being entire, and represents
them distinctly so in his figure of the species, I have changed the generic name to
Pinnularia. I consider it as quite distinct from N. Crabro, Ehr., as described by
Professor SmiTH, in vol. ii., of the Synopsis; for the latter has obscurely monili-
form strize, as is shown in Dr GreEvILLE’s figure of it from Trinidad, in the Micro-
scopical Journal for January 1857.

The forms represented in figs. 11, 12, and 12* of my second paper on Glenshira
(Micr. Trans. iv., pl. v.), and that here figured (fig. 22), are abundant in several
of the dredgings; but of all the numerous examples I have examined, not one
exhibits the slightest trace of moniliform structure; and I have had the satisfac-
tion of having this observation confirmed by Dr GREVILLE, who is acquainted with
the form in which that structure exists obscurely. Unless, therefore, we are pre-
pared to abolish the distinction between entire and moniliform striation, on which
Professor Smitu founds the distinction between his genera Navicula and Pinnu-
laria, we cannot regard this form as a Navicula.

VOL. XXI. PART IV. 6 Q

490 PROFESSOR GREGORY ON

GROUP II.
COcCcONEIDES.

The new forms belonging to this group are not numerous, but they are, in
every case, interesting. In addition to one species, already figured, though im-
perfectly, as occurring in the Glenshira sand, I have detected in the new materials
six additional species, all of them beautiful and well-marked forms. These con-
stitute a largeaddition to a genus, which, in Britain at least, has hitherto been a
very small one. The species to be described are :-—

23. Cocconeis distans, Greg. 27. Cocconeis pseudomarginata, n. sp.
24. ... ornata, n. sp. 28. ... Major, n. sp.

25. ... _ dirupta, n. sp. G, 29. ... Splendida, n. sp.

26. ... mitida, n. sp.

23. Cocconeis distans, Greg. Pl. IX., fig. 23. Form oval, broad ; ends subacute.
Length from 0:0014” to 0:0026"; breadth from 0-001” to 0-002”. Median line
delicate. The valve is marked by distant lines, much inclined near the apices,
not reaching the median line. ‘These lines are about 10 in 0-001", and consist of
white hyaline faint bars, on which are set small and distant granules. The
number of granules is only 4 or 5 in the longest of these lines, so that the gra-
nules are very distant. They are, as nearly as possible, of equal size, and from
their distance, give to the valve a spotted rather than a striated aspect. In the
figure, the granules appear larger than they really are; but this, as I have since
ascertained, depends on the focus, and is an effect of shadow. By careful
focussing, the real size of the granules is easily seen. The valve is hyaline; but
it is always easy, by focussing, to see the faint bars on which the granules are set,
a character which at once distinguishes this form from C. Scutellum, to which
some are disposed to refer it. Another character, besides that of its having much
fewer lines and much fewer granules than the coarsest varieties of C. Scutellum,
is, that in C. distans the granules are of equal size, while in C. Scutellum they
diminish in size as they approach the median line. In C. distans, if there be any
difference, it is that the marginal granules are somewhat smaller than the others.
I may here also allude to the fact, that while C. Scutellwm is a most variable form,
C. distans, so far as I have seen, exhibits only one variety, and that quite dif-
ferent from any variety of C. Scutellum. This form, C. distans, var. 8, premorsa,
is considerably larger than the type, having a length of 0:003" to 0:0038’, and
being a little narrower in proportion than the type. There is always, at one
point of the margin, a notch or solution of continuity, as if a portion had been cut
out, and then smoothed over. The only other difference is, that the granules
are somewhat smaller, but the faint bars are exactly as in the type.

I figured this species, both in my first and in my third paper on the Glenshira

NEW FORMS OF MARINE DIATOMACEX. 49]

sand. But in the former, a variety of C. Scutellum was figured by mistake: and
the latter figure was imperfect, because I had not then seen the faint white bars.
This species, along with C. costata, also figured in the third paper alluded to, is so
frequent in Lamlash Bay, that I have had ample means of studying it, and am
quite satisfied of its being a good species. I may say the same of' C. costata, with
the remark, that I cannot ascertain from EHRENBERG’s figures, whether his Ra-
phoneis fasciolata may not be the same form. Enrenpere’s form seems to be
much larger, and the markings much coarser and more conspicuous. I must
leave this point undecided till I can compare the two forms.

24. Cocconeis ornata,n. sp. PI. IX., fig. 24. Form a pure and elegant oval.
Length about 0:0022”; breadth about 0:0014”. There is a broad marginal band,
marked by strong distant costz, the ends of which are rounded. Within this
band the surface appears concave to the median line, which is delicate, with a
large, definite, central nodule. The middle part is marked by fainter costze, cor-
responding to those on the marginal band, and, like them, so much inclined near the
apices, as to be nearly vertical. There is a narrow blank line between the marginal
and central costa, and the latter do not reach the median line, leaving a long lan-
ceolate blank space in the middle. The whole valve has a rich ornate aspect.

This beautiful species occurs in Lamlash Bay; and although scarce as yet, I
have been able to examine a sufficient number of specimens to ascertain its cha-
racters. I have also observed a few in Loch Fine.

25. Cocconeis dirupta, n. sp. Pl. IX., fig. 25. Forma broad, short oval, some-
times all but orbicular. Length from 0-001” to 0:0024” ; breadth from 0:0007” to
0:0021”. Valve thick, and under the half-inch objective of a strong brown colour.
Median line irregular, like a slit or tear down the middle of the external surface.
The whole valve is marked, except the slit, with coarse, wavy, longitudinal striee ;
but, when carefully focussed, fine transverse strize are seen over the whole surface
to the median line. Under the half-inch, there is an appearance of a long stauros,
which, under a higher power, disappears as such, and can only be seen as a trans-
verse gleam of light from below. The striated surface seems to be an outer one,
torn asunder in the middle, and from this I have named it. Vertical strize about
26, transverse striz about 60 in 0-001”.

I had observed this form in the Glenshira sand, where, however, it was very
scarce, and hardly ever entire, so that I postponed its investigation. It occurs
very abundantly in Mr Mires’s Corallina gathering, and less frequently in several
of the dredgings. ‘There is but one known form which is in any degree allied to
it. Thisis C. diaphana, Sm., which I find to occur along with it. After many
comparisons, I am disposed to conclude, although these two forms are not the
same thing, since C. dirupta is by no means diaphanous, while its strize are con-
spicuous and its colour brown, the strize of C. diaphana being very obscure, and
the valve colourless, that C. diaphana may perhaps be an imperfect form of

492 PROFESSOR GREGORY ON

C. dirupta, possibly the surface which lies under the one here figured, or possibly
also the lower valve, which in Cocconeis is often different from the upper. It is,
however, at least equally probable that these two forms belong to different species.
In the Corallina gathering, C. dirupita is infinitely more frequent than C. diaphana.

26. Cocconeis nitida,n.sp. Pl. IX., fig. 26. Form a very broad oval, suddenly
contracted, above and below, to very short, subacute, produced apices. Length
from 0°001” to 0:0038"; breadth from 0-0008” to 0°0035”. Valve very thick,
aspect glassy. It is marked by lines of very large nitid granules, these lines
forming, longitudinally, concentric strie, the two inner ones of which bend
slightly outwards from the median line, leaving a narrow lanceolate blank space ;
the others becoming more and more curved as they approach the margin. In large
specimens, there are five such lines on each side, or from 3 to 4 in 0-001". But
the granules also form transverse lines, much inclined near the apices, of which
there are, in large specimens, 28 or 30 in the length of the valve, or from 6 to 8
in 0°001".. The margin is marked by a series of finer strie. Median line obscure.
In the middle of the valve, the transverse lines contain on each side five granules,
corresponding to the five vertical lines. The granules are generally of equal size
or nearly so, except a few near the apices, which are smaller. The whole form
is very conspicuous, from its glassy aspect, and the size and brilliancy of the
granules.

This striking form occurs not unfrequently in Lamlash Bay, and sparingly in
the Loch Fine dredgings. It is very uniform in its characters.

27. Cocconeis pseudomarginata, n. sp. Pl. IX., fig. 27. Form a very broad
elliptic, or elliptic-lanceolate. Length 0-0016” to 0:0033". Breadth 0-0011’ to
0-003". Valvethin and transparent. Within the margin is a line or shade parallel
to it; and within this, half-way from the margin to the centre, isa very strong line,
forming a broad lanceolate figure. At first sight it seems as if the latter were the
inner boundary of a marginal striated band; but on close inspection the strie,
which are very fine, are seen to extend from the margin almost to the median
line, where they leave a very narrow rhombic blank space, extending, in the
median line, only to the inner of the two marginal lines. The third, or interior line,
counting from the margin, is a very strong and raised ridge, the ends of which
are almost in contact with the second line. Median line delicate, central nodule
definite ; terminal nodules placed within the ends of the third line. Striz very
delicate, but sharp, about 62 in 0-001”, transverse in the middle, nearly vertical at
the ends. The first or outer margin is formed of two lines very close to each other.

This remarkable form occurs in Professor ALLMAN’s dredging from Lamlash
Bay, where it is rather scarce, and also in that of Mr Mines from the same
locality. It requires a very good glass to resolve the markings perfectly.

28. Cocconeis major, n. sp. Pl. IX., fig. 28. Form avery broad oval. Length
to 0:0015" to 0:0038"; breadth from 0:001’ to 0:00315”. Median line distinct ;

De ee ee ee en

Hal & « b-@ Ad ee co

NEW FORMS OF MARINE DIATOMACEZ. 493

central nodule indefinite. Terminal nodules considerably within the margin,
small. The two parts of the median line terminate in the middle in small rounded
expansions, but do not meet. Strize delicate, but sharp, transverse in the middle,
and gradually more and more curved towards the apices, where they become nearly
vertical. They are not so close together as in some forms in which they are
equally delicate, and there are about 54 in 0-001". Valve thin, flat, hyaline.

This remarkable form occurs in Professor AttMAN’s Lamlash Bay dredging,
where, however, it is rather scarce; also in that of Mr MILzs.

29. Cocconeis splendida, n. sp. PI. IX., fig. 29. Form, a pure broad oval.
Length about 0-0044"; breadth about 0:0039". Valve strong, and very richly
marked with striz, which are highly inclined and curved near the apices. These
striz are coarse, about 14 in 0-001", and. are formed of granules, which gradually
diminish in size towards the median line. The four or five outer granules of each
of the strie are set as closely together as possible, while the rest are separate. This
gives the appearance of a broad marginal band. There is a small, nearly square
blank at the centre, which is no doubt the indefinite central nodule. The two
halves of the median line are strong, somewhat bent at the terminal ends, where
they form elongated expansions, lying just within the dense marginal band. The
central ends terminate in small expansions, which lie at the upper and under
edges of the central blank.

This beautiful form occurs in Lamlash Bay, but it is hitherto scarce. No doubt
it will some day be found more abundantly. It is, with the two preceding forms,
remarkable for the size it attains, being the largest Cocconeis yet described, while
C. major and C. pseudomarginata are but little below it in this respect, and even
C. nitida is unusually large for this genus.

GROUP III.
FILAMENTOUS ForMs.

Of this class of forms, the number is considerable. It is worthy of remark,
that most of them belong, so far as I am able to judge, to the genus Denticula,
which hitherto has yielded only fresh-water species. But there are six of which
the genus is doubtful ; partly because the F.V. alone is as yet known, which is the
case in four of them; partly because, if not Denticule, they cannot well be re-
ferred to any of the genera in Smiru’s Synopsis. One remarkable species, the
genus of which is still uncertain, 1 have been compelled to remove from Himan-
tidium, in which genus Professor Smiru had provisionally arranged it. The forms
of this group are 14; viz. :—

30. Denticula (?) interrupta, n. sp. 34. Denticula nana, n. sp.

31. ... (¢) capitata, n. sp. 30. /.. © MmMor, a. sp.

32. ... (2) ornata, n. sp. 36. ... distans, n. sp.

33. ants (Qamvis, D., sp. 37. ... Staurophora, n. sp.

VOL. XXI. PART IV. 6R

494 PROFESSOR GREGORY ON

38. Denticula fulva, n. sp. 41. Meridion (?) marinum, n. sp.

39. ... Marina, n. sp. (or Gomphonema lineare ?).

40. Diadesmis (?) Williamsoni = Himanti- 42. Pyxidicula (Dictyopyxis) cruciata, Ehr.
dium Williamsoni, Sm. 43. Orthosira angulata, n. sp.

30. Denticula (2) interrupta. Pl. X., fig. 30. Form of F.V. nearly rectangular,
the middle part very slightly convex, and the ends a little expanded. There is
an apparent interruption of the margin at the middle point on each side, and on
each side of this opening is a round punctum. Length about 0:0015"; breadth
about 0:0004”. It occurs in chains of 2, and the two dots of each margin form a
square with those of the margin of the adjacent frustule. The S.V. is not yet
known, and the species is only provisionally referred to Denticula.

This species occurs in Lamlash Bay, but is scarce.

31. Denticula (2?) capitata, n. sp. PI. X., fig. 31. Form of F.V. generally rec-
tangular, but with the middle part considerably convex, and the apices expanded
and rounded. Length about 0:0018”; breadth about 0:0005”. Occurs, like the
last species, in chains of two. S.V.as yet unknown; and it is only doubtfully
and provisionally referred to Denticula.

This species occurs only in one of the Loch Fine dredgings, and it is as scarce
as the preceding.

32. Denticula (?) ornata, n: sp. PI. X., fig. 32. Form of F.V. rectangular, but
somewhat expanded in the middle, and also, after a slight contraction, at the
apices, which are finally truncate. The margin, at the expansions, is beautifully
moulded, having a moulding or notch on each side of the middle point.—Occurs in
chains of two. Length 0-0015” to 0:0017”; breadth, in the middle, 0-0005". S.V.
not yet known, so that the species is only provisionally referred to Denticula.

This very pretty species occurs both in Lamlash Bay and in Loch Fine, and
is much less scarce than the two preceding ones. Notwithstanding this, however,
I have not been able to find the S8.V.

33. Denticula (¢) levis, n. sp. Pl. X., Figs. 33, 336, and 33c¢. Form of F.V.
linear, rectangular, with a small sharp prominence in the middle of each margin,
and the apices slightly, but sharply, expanded. Occurs in chains of two or three,
and also solitary. Length from 0:0016” to 0:0027”; breadth 0:0006”. It is
striated on each side to one-third of the width, indicating that the S.V. is convex.

Strizedelicate, but distinct under a high power, about 48 in 0-001”. The general
aspect is smooth, and the striation is only seen on very careful adjustment. There
are two terminal nodules visible on the F.V. at each end, which are joined by
lines bounding the striz. The middle prominence of the margin of the F.V.
seems to indicate a central nodule on the S.V., which view has not yet been ob-
served.

This species is by no means rare in Lamlash Bay, and it occurs also in Loch
Fine ; but I have hitherto been unable to detect the S.V. I have referred it pro-
visionally to Denticula, but with many doubts. It is probable that if we had the

NEW FORMS OF MARINE DIATOMACEZ. 495

S.V. we might find it to be a Diadesmis, that is, a catenated species, having na-
viculoid frustules. But I do not venture to name it on conjecture, and I only
refer it, with the three preceding forms, to Denticula provisionally, in order that
some name may be used in speaking of them. Indeed it is probable that the
three preceding species may also prove to belong to Diadesmis. My present ob-
ject is, not to determine their genus, for which I do not possess the necessary
data, but only to point them out as well-marked species, for the researches of
other naturalists.

34. Denticula nana, n. sp. Pl. X., fig. 34. Form of the F.V., which occurs in
chains of two, three, four, and occasionally more, rectangular, expanding a little
in the middle, and also at the apices, which are truncate. Length from 0-0005”
to 0-001”; breadth, in the shorter examples, 0:0003” to 0:0004”, and less in the
longer ones. Margin of F.V. faintly denticulate, from the ends of the strie.
S.V. obtusely rhombic, broad, with a raphe in the median line. Strive rather fine,
inclined.

This little form is tolerably frequent, both in Lamlash Bay and in Loch Fine.
I think it is properly referred to Denticula, although it has some resemblance to
some of the forms figured by foreign authors under the name of Zygoceros.

35. Denticula minor, n. sp. Pl. X., figs. 35, 356, 35, and 35d. Form of F.V.,
which occurs in chains of from two to seven or eight, on the whole rectangular; .
sometimes exactly so, more frequently with an angular expansion at the apices,
which become capitate and subtruncate, while the margin is convex in the middle.
Length from 0-0005” to 0-002”; breadth from 0:0002” to 0-0006”. Margins of
F.V. strongly denticulate. S.V. rhombic or rhombic-lanceolate, very narrow, with
srong marginal costze. Costz 18 or 20 in 0-001”.

This form, which is very frequent in the Lamlash Bay dredgings, and also in
one of those from Loch Fine, varies much both in size and shape, the F.V. being
sometimes as short as the shortest J). nana, and very broad in proportion, bulging
in the middle, and capitate, sometimes longer, rectangular, and broad ; and most
frequently longer, much narrower, and capitate. The S.V. is so narrow, that the
frustule seldom lies on that side, so as to present it to the eye. It appears to
belong distinctly to Denticula.

36. Denticula distans, n. sp. Pl. X., figs. 36 and 366. Form of F.V., which oc-
curs in chains of from two to five or six, and also solitary, rectangular, rather broad:
often convex on the sides, and with the ends a little expanded. Margin strongly
denticulate. Length 0:0017” to 0:0026”; breadth 0:0006” to 0-0008”. S.V. rhom-
bic or rhombic-lanceolate, broad ; marked with very strong, distant, sharp, and
marginal costz. Terminal nodules large and conspicuous. No central nodule.
Costze about 10 in 0:001”. Valve thick and glassy.

This fine species is tolerably frequent, both in Lamlash Bay and in Loch Fine.
There is a considerable resemblance between this and the preceding species, so

496 PROFESSOR GREGORY ON

that D. minor almost looks like a miniature of D. distans ; but on a close compa-
rison, they are found to be totally distinct. D. distans often occurs shorter than
the average length of D. minor, but it never loses its own characters, the strong,
distant, glassy costa, and the broad S.V. But the two forms are evidently allied
species, and both seem to be true Denticule.

37. Denticula staurophora, nu. sp. Pl. X., figs. 37, 376, and 37¢. Form of
F.V., which occurs in chains of two, three, and sometimes more, rectangular, with
coarse marginal strize, which in the middle on each side, are interrupted by a
blank space, bounded by diverging lines. Length from 0-001” to 0:0038”; breadth
0:0005” to 00008”, the shorter examples being the broadest. S.V. lanceolate, rather
narrow, marked with coarse moniliform striz, except in the middle, where there
is a broad stauros, on each side of which is a line, curved and concave towards
the extremities. Striz 14 to 16 in 0-001”.

This striking form is not unfrequent either in Lamlash Bay or in Loch Fine.
I have referred it to Denticula, but perhaps it ought to be referred to Diadesmis,
or, if the stauros be considered an objection, to a new genus allied to Diadesmis
as Stauroneis is to Navicula. But this point must be left for farther investi-
gation.

38. Denticula fulva, n. sp. Pl. X., figs. 38 and 386. Form of F.V., which oc-
curs in chains of two, three, and sometimes four, linear, rectangular, and slightly
expanded at the apices, the margin marked with the ends of somewhat coarse
striz. Length from 0-0018" to 0°004’; breadth 0-0005". S.V. linear, narrow,
broadest in the middle, and gradually contracting to long, narrow extremities,
which are ultimately subcapitate and rounded. Strize moniliform, somewhat
coarse, leaving a raphe in the middle, and the two terminal knobs unstriated.
No central nodule in the 8.V.; but the two nodules seen at each end of the F.V.
appear to form the unstriated knobs at each end of the S.V.

This well-marked species occurs with the three last, and is even more fre-
quent than they are. The genus cannot be considered as determined with cer-
tainty.

39. Denticula marina, n. sp. Pl. X., figs. 39 and 396. Form of F.V. linear,
rectangular, with the angles very slightly expanded, and the margin strongly
denticulate. It occurs in chains of from 2 to 18 or 20, so that the filament
seems to be tenacious. Length from 0:002"’, to 0-008’ or 0:009"; breadth from
(0-0003" to 00005". S.V. linear, expanded at the middle, and obtusely acuminate
at the ends. Strize very coarse, and very coarsely moniliform, about 10 in 0-001”.
On each side of the median line each of the strize is formed of only two granules,
which are distant, and half of a third, which seems to be on the margin. The two
or three central strize on each side, having only one and a half granules, the inner
granule of each being absent, there is a blank space round the centre; and there
is a smaller blank at each apex. The F.V. here figured is of about the usual

NEW FORMS OF MARINE DIATOMACEZ. 497

length, the S.V. is one of the longest. The whole form has a pale, whitish aspect
on the S.V., and the single valves are hyaline.

This very fine and conspicuous form is frequent in Lamlash Bay, and even
abundant in one of the Loch Fine dredgings. It occurs scattered in all the dredg-
ings without exception. It seems to be a true Denticula.

40. Diadesmis (?) Willamsoni, n. sp. Pl. X., figs. 40 and 406. Form of F.V.
rectangular, narrow, with three angular expansions, one in the middle, and one at
each end; so that there are two long, narrow elliptical spaces between the adjacent
frustules, which occur, as in the last species, in chains of from two to twenty, and
upwards. Margin of F.V. strongly denticulate. Length from 0-0016’ to 0-008’ ;
breadth from 0:0004" to 00005". S.V. linear, narrow, straight, very slightly in-
curved in the middle, and acuminate at the ends. Strize coarse, coarsely monili-
form, but closely set, giving to the valve a black aspect; about 16 or 18 in
0:001”. Central and terminal nodules large, white, conspicuous.

This remarkable and conspicuous form occurs with the last, and is even more
abundant, especially in two of the Loch Fine dredgings. It is found in all the
materials. The F.V. has been described and figured by Professor Smiru, as having
occurred sparingly in a dredging made by Mr G. Bartez, off the coast of Skye,
and detected by Professor Wintutiamson. It was referred by Professor Smiru, but
doubtfully, from the absence of the S.V., to Himantidium. The 8.V. is particularly
frequent in one of my Loch Fine dredgings, and certainly cannot belong to Himan-
tidium. 'The nearest genus is Deadesmis; but I do not feel at all sure that it is
the true one. The conspicuous nodules agree with it ; but the aspect of the species
is unlike that of any known Diadesmis. I therefore give it as such with a doubt,
and am satisfied with having, in the meantime, ascertained that it is not a Hi-
mantidium. 1 would indicate one curious character, that the striz, on the F.V.
seem to pass across the intervals between the adjacent frustules. This seems
also to have been observed by Professor Situ, as it is represented in his figures
of the F.V., which are accurate. I have also observed, that the shortest examples,
which are sometimes so short as to be nearly square on the F.V. are not only
broader on both views than the larger ones, but also devoid of the central expan-
sion or undulation, seen on the F.V. In this state, they approach in form to the
rectangular F.V. of D. disians, but are at once recognised by the closeness of the
strive, as well as by their moniliform character. In one dredging I find many long
filaments, especially of the shorter frustules ; while in another, treated precisely
in the same way, the detached frustules, generally exhibiting the 8.V., and much
longer, are much more common than the chains.

41. Meridion (?) marinum (or Gomphonema lineare (?)),n. sp. Pl. X., figs. 41
and 416. Form of F.V., which occurs in chains of two, three, or four, both in
entire apposition, or attached only by an angle at the broader end, cuneate and
truncate at both ends, and narrow. It is marked with coarse marginal denticu-

VOL. XXI. PART Iv. 6s

498 PROFESSOR GREGORY ON

lations. S.V. linear, narrow, broadest at a point above the middle, from which it
becomes narrower both ways; the shorter half being rather broader than the other,
and rounded at the apex. The longer and narrower half is also rounded, and
very slightly expanded at the end. Strize coarse, not reaching the median line,
but leaving a somewhat broad raphe in the middle. Striz about 16 in 0:001’;
Length about 0:0015"; breadth of F.V., at larger end, 0°0004’, at smaller end,
0:0003". Breadth of S.V. 0:0002’ at the broadest point.

This form resembles both a Meridion and a Gomphonema. The absence of a
central nodule prevents me from referring it to the latter genus; and with reference
to the former, the mode of attachment, as well as the form of the frustules, agree
pretty well with it. But I have not seen more than four attached; so that it is
still doubtful whether it forms a spiral filament, as the slightly cuneate frustules
must tend to do. It occurs, by no means sparingly, both in Lamlash Bay and in
Loch Fine. Future observations on the living form will decide the question of
its generic position, but in the meantime it is a well-marked species.

42. Py«idicula cruciata, Ehr. Pl. X., fig. 42. Form of V. cup-shaped, hemi-
spherical, with hexagonal cells over the whole surface, and in one direction, a
crest composed of square or irregular cells running round the hemisphere in a
plane at right angles to that of the junction of the two valves. Cells large, and
of uniform size. Diameter 0:0019".

The form here figured is only a detached valve, the entire frustule not having
yet occurred in these dredgings. But it agrees precisely with EnRENBERG’s figure
of the valve. The specific name is given on account of the arrangement of some
of the cells, as seen in a view obtained by looking down on the frustule, at right
angles to the junction, in the form of a broad rectangular cross. This cannot be
seen in the view here figured. The species is very scarce as yet, having occurred
very sparingly in Lamlash Bay. But it is interesting, as being one of the forms
which ExRENBERG has figured from the gina Clay Marl already mentioned at
p. 482, and from the deposit of Richmond, Virginia. I have placed it in this
group, because I have reason to think that Pyxidicula is a catenate form,
though we cannot expect to see this in fossil deposits. I would here refer to
the beautiful new form, detected by Professor WaLKER ARNorTT, and figured in
the Appendix to this paper, which, in the frustules, is so closely allied to the
present species, that it may prove to be actually P. appendiculate of EHRENBERG,
a form which occurs along with P. cruciata. Professor W. Arnott’s form is
decidedly catenate.

43. Orthosira angulata, n. sp. Pl. X., figs. 43 and 43 6. Form of F.V., which
occurs solitary, and in chains of from two to six, rectangular in the midalel acu-
minate and truncate at the ends. On the margin, which is often slightly incurved,
are seen denticulations arising from the cells of the disc or S.V. Length from
0:0005’ to 00015"; breadth of F.V. from 0:0003’ to 0:00045". Diameter of disc,

NEW FORMS OF MARINE DIATOMACEZ. 499

0:0005’ to 00015". Disc cellulate; cells largest in the centre, becoming regularly
smaller towards the margin, arranged in quincunx, but, from the diminishing
size of the cells, in curve lines. It often happens that the cells in the two inner
thirds of the disc are conspicuously seen, inclosed within an equilateral triangle.
formed by three slightly curved lines of cells, beyond which the cells and lines of
cells are so small and hyaline, as to become obscure. Such discs are convex, and
seen on the convex side. Others, especially the largest, are much flatter, and,
when properly focussed, exhibit the whole cellular structure plainly.

This species is very frequent, even abundant, in Professor ALLMAN’s dredging
from Lamlash Bay; and it is found more or less frequently in all the others.
Possibly the disc is identical with the Coscinodiscus minor of EHRENBERG or
Kirzine ; that of Professor Smiru being a fresh-water form. But the present
species is unquestionably an Orthosira, notwithstanding the resemblance of the
disc to Coscinodiscus.

GROUP IV.
Discs, INCLUDING CAMPYLODISCI.

The new forms belonging to this group are not, in the materials examined,
very numerous, but they are very interesting, and most of them are very fine
species.

44, Melosira or Coscinodiscus (?) n. sp. 50. Eupodiscus subtilis, Ralfs, n. sp.
45, Coscinodiscus nitidus, n. sp., G. 51. Campylodiscus centralis, n. sp.
46. sd punctulatus, n. sp., G. 52. sop Ralfsii (¢) Sm.
47. se concavus, Ehr., G. 53. 6 angularis, n. sp.
48. nas umbonatus, n. sp. 54. AS eximius, 0. sp.
49. ne centralis, Ehr., G. 55. aes limbatus, Bréb.
44. Melosira or Coscinodiscus (?) (?),n. sp. Pl. X., fig. 44. Diameter

of disc 0:003". It is marked by fine, sharp, radiate lines, which are very numer-
ous. These lines are strongest near the margin, which has the form of a broad,
thick, raised rim, within which the valve’seems to sink and then to rise, the middle
part being apparently somewhat convex.

This disc occurs not very unfrequently in one of the Loch Fine dredgings, and
more sparingly in one from Lamlash Bay. As no view of it is to be seen except
the disc, or 8.V., I have not been able to determine its genus, although the disc
looks more like that of a filamentous form than a Coscinodiscus.

45. Coscinodiscus nitidus, n. sp. Pl. X., fig. 45. Diameter of disc 0:0012” to
00025". Margin entire, transversely striated. Strise of margin about 16 in
0-001’, traceable to some small distance beyond the marginal band towards the
centre. Surface of disc marked with distant and irregularly radiate lines of
rather large, round, distant cells or granules. The rays are distinctly marked to-

500 PROFESSOR GREGORY ON

wards the margin, but somewhat confused towards the centre. Puncta or granules
larger towards the centre than at the margin. Aspect of valve glassy, puncta
nitescent, very much as in Cocconers nitida (fig. 26).

This pretty disc was figured without a name, from an imperfect specimen, in
my last paper on the Glenshira Sand (Zrans. Mic. Soc., vol. v., pl. i., fig. 50).
Having found it tolerably frequent in Lamlash Bay, I now figure a perfect exam-
ple, which, provisionally, I refer to Coscinodiscus.

46. Coscinodiscus punctulatus, n. sp. Pl. X., fig. 46. Diameter of disc 0°003"
to 0:0036". It is marked by very fine and obscure lines, which, near the margin,
are traceable as rays, but which soon become fainter, and apparently wavy at the
same time, as they proceed towards the centre. Over the whole surface are
scattered, sparsely, small puncta, which, in a certain focus, appear as points of
light.

This disc was also figured, but not named, in my last paper on the Glenshira
Sand (Trans. Mic. Soc., vol. v., pl. i., fig. 48); but the specimen here figured is
a better one, and shows more of the very obscure structure. It is impossible, in
the present state of our knowledge of it, to refer it with certainty to any genus;
but it may be a Coscinodiscus. It occurs in Lamlash Bay and in Loch Fine, but
is not very frequent. It may possibly prove to be the end view, or the dissepi-
ment, of a Melosira or an Orthosira.

47. Coscinodiscus concavus, Ehr. Pl. X., fig. 47. Diameter of disc 0-0025’ to
0-0043". Margin entire, transversely striated. Strise about 10 in 0-001". Surface
concave, covered with large, equal, hexagonal cells, arranged as in a honey-
comb.

This beautiful disc occurs rather sparingly both in Lamlash Bay and in Loch
Fine. It agrees exactly with one of EnrenBeErG’s figures of C. concavus. But in my
last paper on the Glenshira Sand, I have figured another disc (Trans. Mic. Soc.,
vol. v., pl. i., fig. 52), which differs from the present form in having a punctum
in the centre of each cell, and in the margin being formed of very large cells,
divided by strong bars, which appear to project from the plane of the valve, and
which also extend beyond the outer margin. This disc I at first suspected to
belong to some of the Polycystineze; but I afterwards found it figured by EnREN-
BERG as C. concavus. I confess that I cannot believe these two discs to be of one
species ; but that represented in fig. 47 seems to be a true Coscinodiscus; and as
it is identical with one of EurenBerG’s examples, we may consider it as the true
C. concavus, leaving the other for farther investigation. (I have recently found,
in some of the Clyde dredgings the other disc, just alluded to as having been
figured in my paper on the Glenshira Sand, and as being also named by Enren-
BERG, C’. concavus.)

48. Coscinodiscus umbonatus, n. sp. Pl. X., fig. 48. Diameter of dise about
0:0045". Surface densely cellulate, having a broad, nearly flat, marginal zone,

NEW FORMS OF MARINE DIATOMACEZ. 501

the central portion being almost or quite hemispherical. It is so convex, that,
when the marginal zone is in focus, the middle part appears asif full ofair. Cells
in lines, generally radiate, rather small, irregular in outline, and unequal in size to
some extent. As the rays diverge from each other towards the margin, the space
is often filled up by a bifurcation of the rays, which gives an aspect of irregularity
to the markings.

This fine disc occurs in one of the Lamlash Bay dredgings, in which, however,
it is very scarce indeed. We must hope that it will be found in greater abun-
dance. The broad marginal zone or brim, and the very convex middle part, give
to it a great resemblance in shape to a “wide awake” hat; but I have named it
from its resemblance to a shield with a large boss in the centre.

49. Coscinodiscus centralis, Ehr. Pl. XL. fig. 49. Diameter of disc 0-004’ to
0-009", or even 0°01". Surface regularly cellulate. Cells rather small, hexagonal,
equal, except at the centre, where there are three large oblong cells, meeting in
a point; and between these, a little farther from the centre, three more cells,
a little smaller. The valve is remarkably transparent, and from this, and the
small size of the cells, it is apt to be overlooked, although, when accurately
focussed, the cells are very distinct. It has frequently a yellow or straw colour,
in balsam, under the 4-inch objective.

This very beautiful disc is by no means rare in the Glenshira Sand; but when
I described that deposit, I was not well acquainted with the discs figured by
EHRENBERG, and supposed it to be a form of C. radiatus, or else C. concinnus. It
agrees exactly with EHRENBERG's figure of C. centralis. It occurs not unfrequently,
both in Lamlash Bay and in Loch Fine, and it reaches occasionally a diameter
exceeding that above mentioned.

50. Hupodiscus subtilis, n. sp. (Ralfs.) Pl. XI, fig. 50. Diameter of disc
00033’. Surface apparently convex, very hyaline, and very densely marked with
fine lines, and indications of minute cells, of which the lines are probably com-
posed. In the centre is a rather large circular spot, and the usual pseudo-nodule
of the genus is placed close to the margin.

This disc was first noticed by Mr Ratrs in the early part of this winter
(1856-57). He distributed specimens as probably Coscinodiscus concinnus ; but
when Dr GREVILLE and myself came to examine it with object-glasses of high
power and of superior quality, it was soon recognised as an Eupodiscus. This,
so far as I know, was first done by Dr Grevinur. I had frequently observed a
disc like it, with very delicate and obscure markings, in some of my dredgings ;
but it was Dr GrEVILLE also who first ascertained that these discs, which I had
taken for granted were Coscinodiscus concinnus, were really identical with the
disc of Mr Ratrs. As the form occurs in these dredgings, therefore, though less
abundantly than in Mr Ratrs’ gathering, I figure it here as an Eupodiscus.

51. Campylodiscus centralis,n. sp. Pl. XI, fig. 51. Form orbicular, or nearly so.

VOL. XXI. PART Iv. 6 T

502 PROFESSOR GREGORY ON

Surface marked with strong canaliculi, which are broad near the margin, narrower
towards the centre, near which they terminate in a portion of the middle of the
median line; in length about two-fifths of the diameter. At about one-third of the
radius, or a little more, from the margin, is a strong shade, probably a ridge or
elevation, of a nearly square outline, placed diagonally to the median line, which
passes through two of its angles. Halfway from this ridge to the centre is a
second ridge of a circular form, inclosing the elongated centre, from which the
canaliculi arise. The radiating canaliculi are fainter within the square ridge,
stronger outside of it; they diverge as they approach the margin, near which
their ends are joined by semicircular loops, forming a scalloped inner margin,
beyond which is an entire outer margin. Diameter about 0-0021". Canaliculi
about 40 in a disc of that size.

This species occurs very sparingly in one of the Loch Fine dredgings, and none
of those I have seen are larger than the one figured. It is probable, however,
that it may occur of greater dimensions, as the next species does.

52. Campylodiscus Ralfsiit, Sm. (2). Pl. XL, fig. 52. Diameter 0-003" to
(:0045". Form orbicular in many instances, but with all the modifications of the
genus. From two points in the median line, near its extremities, arise two lines,
diverging in the middle, so as to leave a long, narrow, vacant space, the width of
which varies from 0-0003” to 0:0005", according to the size of the valve. To these
lines the canaliculi reach. These canaliculi are narrow, very short near the ends
of the median line, longest in the middle, where they reach a length of from
(0013 to 0:0017".. Near the margin each expands into a small round head, and
beyond the line of these heads, the margin is entire. Canaliculi in a disc such
as is here figured, 64, curved as they approach the ends, having their concavity
turned from the centre. The valve is much undulated.

This fine and conspicuous form first occurred to me in the Glenshira Sand,
where it is scarce. Iafterwards found it, still scarce, in Professor ALLMAN’s Lam-
lash Bay dredging; and still more recently, I found it frequent in three of the
Loch Fine dredgings. I have referred it to C. Ralfsii, Sm., although it is so
much larger than the form figured by him, and although there are other differ-
ences. Thus in C. faljsii, Sm., the canaliculi reach the median line, and the row
of heads or expansions lie some distance from the margin. But these differences
cannot be regarded as specific. The smaller variety figured by Smirx occurs also
in some of the dredgings and in the Glenshira Sand. But the larger form seems
to be the typical one, and for that reason, chiefly, I have here figured it.

53. Campylodiscus angularis, n. sp. Pl. XI., fig. 53. Valve orbicular, with the
usual modifications. Diameter of disc from 0:0025’ to 0:0039", the smaller sizes
being the most frequent. The canaliculi from 160 to 180 in large examples,
such as the one here figured. They are very short at the ends of the median line,
and inclose a broad blank space, which, in the median line, occupies the whole

NEW FORMS OF MARINE DIATOMACEZ. 503

diameter, but in the middle, in a line at right angles to this, extends to less than
half the diameter. Hence the canaliculi form a broad marginal band, except near
the ends of the median line, where it is narrow; and the vacant space is ellip-
tical, suddenly contracted at the ends to narrow processes, which traverse the
band of canaliculi at its narrowest part to the very margin. At the roots of these
processes, the canaliculi suddenly recede from the median line. They are much
inclined at the extremities; and the longest are from 0-0008" to 0-015’ in length.
The true median line is visible, and is very delicate; but there are no other mark-
ings visible on the vacant middle space.

The surface of the valve, both above and below, that is, near both ends of the
median line, is suddenly bent back, so as to form an angle with the rest of the
valve. On the surface thus bent, short lines appear, apparently between the ca-
naliculi, which lines terminate abruptly. The greater part of the valve, and espe-
cially that part on which are the canaliculi, is convex, which causes the canali-
culi to appear curved. -

This species is frequent in one of the Loch Fine dredgings, and occurs more
sparingly in two others. I have named it from the angular bending back of the
valve.

54. Campylodiscus eximius, n. sp. Pl. XI, figs. 54 and 546. Form nearly or-
bicular, and sometimes nearly square, with the usual modifications. I have seen
one specimen spiral, like C. spiralis. Diameter of disc from 0-004" to 0-007’ or even
0-008". Canaliculi strong, very numerous, about 150 in average specimens; con-
fined to a marginal band, the width of which is generally about 0-0007’ or 0-0008’.
The middle space is pale and hyaline, and at first appears blank; but on close
inspection is seen to be covered with pretty large, very transparent, round granules,
which are not arranged in any order, but indiscriminately scattered, like the points
in shagreen. The median line is marked by a raphe, the ends of which, as of the
middle space, do not, as in the preceding species, traverse the band of canaliculi.
There is, at each end, a small point of the middle space which indents the mar-
ginal band, that being a very little narrower there than it is elsewhere.

This very fine and conspicuous form is very frequent in one Loch Fine dredg-
ing, and less so in two others. At first I thought it might be identical with C.
Hodgsonii, Sm., of which one example is figured as large as this form. But in
his description, Professor Smirx describes the middle space as marked by strong
radiate lines, formed of large granules; and although I have not seen any of C.
Hodgsonii of this large size, yet I find the small ones to agree exactly with this
description. Now in C. eximius, not only is the valve in the middle not marked
with strong radiate lines, but under a low power it appears at first sight blank;
and the very transparent granules are in general quite irregularly disposed, and
only in some instances show faint traces of a linear arrangement close to the
marginal band. As farasI have been able to judge, I am satisfied that the small

504 PROFESSOR GREGORY ON

C. Hodgson is not of the same species as C. eximius. And with regard to the
large C. Hodgsonit of the Synopsis, not having seen it, I am unable to decide.
But if it be, as the figure indicates, as strongly marked as the small one, it cannot
be C. eximius. If, on the other hand, it should prove to be like C. eximius, then
it is probable that it will be found to differ specifically from C. Hogdsonii.

55. Campylodiscus limbatus, Bréb. Pl. XL, fig.55. Form orbicular. Diameter
from 0-005" to 0:008’. Canaliculi marginal, short, broad, transversely sulcate, so
as to appear, on close inspection, almost moniliform. Within this marginal band
is another fainter band (the outer one being strong and black), which looks almost
like the reflection in a mirror of the first, except that the bars in it are more de-
cidedly moniliform, or formed of more distinct granules, which, near the median line,
extend from both ends towards the centre, in a broad band, which becomes gra-
dually narrower and fainter as it proceeds, and is lost on both sides before reach- |
ing the centre. In Dr Bresisson’s figure these projecting bands reach the centre,
but I have not been able to trace them so far, and have only done so with diffi-
culty, so far as I have traced them.

This very fine and striking form is not unfrequent in two of the Loch Fine
dredgings. About four years ago, I observed a fragment of a large Campy-
lodiscus in a marine gathering from Oban, which was not known to Professor
SmitH; but I did not describe it, having waited for an entire specimen, which I
did not meet with till this last October, when it proved to have been a fragment
of C. imbatus, which Dr Bresisson had shortly before figured as occurring at
Cherbourg.

GROUP V.

AMPHIPRORA.

Of the genus Amphiprora, the new species in these dredgings, though not
very numerous, are very interesting. One form is very doubtfully referred to
this genus.

56. ipo pusilla, n. sp. 60. ema obtusa, n. sp.

57. plicata, n. sp. 61. maxima, n. sp., G.

58. oe elegans, Sm, 62. rs (2) complexa, n. sp., G.
59. m lepidoptera, n. sp., G.

56. Amphiprora pusilla, n. sp. Pl. XIL., figs.56 and 566. Form of the F.V.
nearly rectangular, a little incurved in the middle, and expanded at the extremities.
Above each valve lies a plate, in shape like a narrow arc of a very large circle, the
convex edge outwards, the middle of it slightly overlapping the central constric-
tion, while the ends coincide with the inner terminal angles of the valve. Length
about 0:0027’; breadth, including plates, at the middle, 0°0008". S.V. lanceolate,

NEW FORMS OF MARINE DIATOMACEZ, 505

narrow, and, but for the absence of apiculi, a miniature of that of Apr. lepidop-
tera. (See farther on, fig. 59 6.) Both views, and also the plates, are marked with
very fine transverse and parallel striz, which, however, on the F.V. do not ex-
tend to the rectangular space between the valves. - Strise about 60 in 0-001’.

This pretty little species has occurred only in one of the Loch Fine dredgings,
where it is rather scarce. It is remarkable for the occurrence of the lateral
plates, which we shall find in several other species, and which perhaps ought to
constitute a new genus. But the resemblance to Amphiprora is so great in other
points, that I do not think it advisable to separate these species from that genus.

57. Amphiprora plicata, n. sp. Pl. XIL, fig. 57. F.V. deeply constricted, with
rounded extremities, which are very broad. Inner margin of valves straight.
On each valve lies a plate extending from the inner margin of the valve to the
nodule; its outer or convex margin being a little incurved in the middle, and
bent forward at the ends, to join the inner angles of the valve. The rectangular
space joining the two valves is marked with faint vertical lines or folds; and the
valves and lateral plates, as well as the rectangular space, are all marked by fine
transverse strize, about 50 in 0:001". Length 0:0037"; breadth from nodule to
nodule 0:00075", at broadest part 0:0016". Outer margin double. S,V. not yet
certainly known.

This species occurs with the preceding, and is equally scarce. It approaches
nearest to Apr. alata, but differs from it in the folds of the middle space, and in
the presence of the lateral plates.

58. Amphiprora elegans, Sm. Pl. XIL., figs.58 and 58 6. Form of §.V. linear-
lanceolate, ends obtuse. Valve traversed by two longitudinal lines, and marked
by fine but distinct transverse strize. Length from 0:0085’ to 0-012"; breadth of
S.V. about 0:0011". F.V. rectangular, with two longitudinal lines. Strize 44 in
0-001", parallel.

I have figured the S.V. of this fine form, first noticed by Mr BLeaK ey, be-
cause, although described in vol. ii. of the Synopsis, no figure of it has yet appeared.
It occurs both in the Glenshira Sand, and in more than one of the dredgings; but
more frequently in one of those from Loch Fine than in any of the others. The
valves are, in these deposits, generally detached, so that I have not met with the
entire F.V. Iam indebted to Mr Roper for an entire specimen, fig. 58 0.

59. Amphiprora lepidoptera, n. sp. Pl. XIL, figs. 59, 596, and 59¢. Form of
FY. linear, constricted in the middle, expanded at the apices, which are flatly
rounded. Length from 0:0055" to 0-008’; breadth of F.V. in the middle 0-0009",
near the ends 00015". SV. lanceolate, with acute ends, terminating in small api-
culi. Central nodule strongly marked; median lines somewhat curved, meeting
in the nodule. Striation fine, parallel, about 48 in 0-001"; on the F.V. the strize
are absent from the middle space. The form of the F.V. with its long slender
alee, is very elegant.

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506 PROFESSOR GREGORY ON

(Since this paper was read, I have ascertained that the peculiar plates above
mentioned in Apr. pusilla, and in Apr. plicata, occur also in this species. I had
overlooked them, from their being very narrow. They rise from the inner margin
of the valves, as seen on the F.V., from two points a short distance from the ex-
tremities. Their convex margin extends in the middle just beyond the constric-
tion. They are so narrow as to be readily overlooked, but are quite distinct,
and appear to be thicker at the outer or convex margin than at the inner or plane
one. There is even some appearance of a second plate in each valve, rising from
the same line, as that just mentioned, but apparently extending in a plane at
right angles to the surface of the valve, so that, in the F.V., it is seen foreshortened.
and appears as a dark line. But I am not yet satisfied about this second plate.

The plates first named constitute a very peculiar feature, both in this species,
and in the two previously described. We shall see the same structure still more
developed in another species, a very remarkable one, namely, Apr. maxima.)

The form represented in fig. 59 c, I am satisfied belongs to this species; but I
do not quite understand its relations. It is of an elegant rhombic-lanceolate
form, with two curve-lines on each side, which at the middle bend inwards, to
join a strong stauros, interrupting the median line, and at the ends coalesce with
the margin. The whole valve is marked with fine parallel striz, except the
stauros. This form, as will be seen, differs considerably from the usual 8.V., (fig.
59 6), which latter often occurs with the longitudinal lines in it much more curved
than in the example figured. Can the lateral lines in fig. 59 ¢ be the outer mar-
gins of the two plates, above described, or perhaps of those suspected to lie in a
different plane ?

This species first occurred to me in the Glenshira Sand, and I figured the S.V.
as Apr. vitrea, 8? in my first plate of that deposit (Mic. Jour., vol. iii., pl. iv.,
fig. 14, the larger of the two figures, which shows the curved lines above alluded
to, with a third line to the side); and the F.V. in my third plate (7rans. Mic.
Soc., vol. v., pl. i., fig. 39). But the former had not the strize, and the latter was
from a very inferior specimen, and, besides, did not show the peculiar plates.
I have therefore figured both views here from good specimens, which are frequent
in Mr Mites’s Corallina gathering from Corriegills, near Lamlash Bay. It is at
once distinguished from Apr. didyma by its much more elegant form, and by
being twice as long. The 8.V., also, is quite different. Iam informed by Dr
GREVILLE that he finds this form abundantly, even predominating, in a dredging
or gathering from nearly the same locality, which he made early last summer.

60. Amphiprora obtusa, n. sp. Pl. XIL., fig. 60. Form of F.V. linear, broad,
with rounded ends, slightly incurved in the middle. The termination of the
middle space projects a little beyond the general curve of the apices. The inner
margin of the striated part of the valve is gently and gracefully curved, forming
two concave lines towards the middle, which meet in a point of the inner margin

NEW FORMS OF MARINE DIATOMACES. 507

of the valve, in a narrow, elongated nodule, which is in a line with the terminal
nodules, also long and narrow. But close to the outer margin, at the constric-
tion, is another large round nodule. The narrow portions, which lie between
the curve-lines just mentioned and the inner margin of the valve, appear, like
the middle space, to be unstriated ; but perhaps this is because they lie in a
different plane from the outer compartments. And even in the last, the strize are
too fine to be resolved under a power of 400.

This remarkable form occurs in one of the Loch Fine dredgings, where, how-
ever, it is very scarce. I have not yet recognised with certainty the S.V., but
there are some forms which may prove to belong to it. .

61. Amphiprora maxima, n. sp. Plate XIL., figs. 61and 610. Form of F.V.
rectangular, very broad, but deeply constricted in the middle, and rounded on the
ends. Length 0°0068"; greatest breadth 00028’ to 0-003", breadth of frustule at
constriction 00017’. Central nodules large, situated close to the constriction in
the outer margin. Terminal nodules on the inner margin of valves, conspicuous.
Over each valve lies a strong, broad plate, arcuate outwards, straight on its inner
margin, which coincides with that of the valve. Outer margin of plate prominent
in the middle, and on each side of this prominence slightly incurved; thick, over-_
lapping the valve at the constriction. Breadth from the margin of one plate at
this point to that of the other 0:0023’. Valves and. plates transversely striated.
Strize distinct, parallel, about 36 in 0-001", thicker and apparently coarser at the
margin of the plate. 8.V. lanceolate, ends acute, with a trace of a constriction just
before the apices. Greatest breadth 000125". Two strong lines, as in Apr. lepi-
doptera, proceed from the apices, on one side, and curve inwards to join a large
nodule at one-third of the width. Round this nodule the strize are curved, as if
pushed outwards. Between the nodule and the nearest margin the strize are very
short, and they leave a large blank space, extending tothe margin. Valve thick and
very convex on the 8.V. Query, Are the curve-lines on the 8.V., the outer margin
of the plates, seen on the F.V? From the convexity of the S.V. its striation is more
conspicuous than that of the F.V.

This, which is one of the finest and most interesting forms described in this
paper, first attracted my attention in the Glenshira Sand. But I could only find
there halves of the F.V; and I postponed the description of it. In Professor ALL-
MAN'S Lamlash Bay dredging I again saw these halves occasionally ; but it was
not till I examined, in October last, the Loch Fine dredgings, that I found, in one
of them, besides a number of the same halves, some entire frustules ; and finally,
the S.V. which, from its comparative narrowness, is seldom presented; the frus-
tule or detached valve lying on its broadest side. There is something very beauti-
ful in the entire form; and in its structure it is peculiarly interesting, as present-
ing the peculiar lateral plates, already noticed in Apr. pusilla, Apr. plicata, and
Apr. lepidoptera, and that ina high degree of development. The occurrence of

508 PROFESSOR GREGORY ON

these plates in four species, all of which have the general aspect of Amphiprore,
naturally leads to the inquiry, whether this remarkable structure may not be
found in all the species of the genus, or whether the forms in which it occurs
ought not to form a new genus. I understand from Mr Roper, that he has found
this species in a marine gathering from the coast of Wales, or of the south of
England.

62. Amphiprora (2) complexa,n. sp. Pl. XIL., figs. 62 ; 62, 6; 62,c; 62,d; and
62,e. Form elliptical, broad, with a constriction in the middle, and broadly rounded
ends. The frustule is composed of two arcuate and constricted segments, which
are broad, thick at the outer margin, thin at the inner margin, and placed oppo-
site each other, with a narrow interval between them. Over the middle of these
two lateral segments is placed a complex mass, formed of five or six segments,
converging inwards and on the ends, like the segments of an orange or melon.
The thick backs of these central segments, marked with transverse strie, are
alone seen in the entire frustule, and those of the outer segments approach near
to the outer margins of the lateral or flat lying segments, leaving only part of
the surface of the latter exposed. A convex line joins the convergent ends of the
central segments

When the frustule, as often happens, falls asunder, a number of segments are
found lying near each other. Some of these have no constriction, and no nodule;
these I take to be the segments of the central mass. Those with nodules at the
middle of their outer margin, at the constriction, seem to be the lateral seg-
ments.

Length of frustule 0-0035’ to 0-004"; breadth 0:0028’. Segments arcuate, broad ;
some with a nodule and constriction on the thick convex or outer margin, others
without. Surface of segments finely striated; strize about 45 in 0°01, delicate,
radiating from the thin or inner margin, and curved near the ends of the segment.
At the margin, there is a row of conspicuous puncta, about 1 for every 2 striz.
The backs of the central segments, when 2m sitw, are striated, but exhibit neither
nodule nor puncta.

It is with much doubt that I refer this very curious form to Amphiprora;
which I should not do, were it not that the lateral plates in four species already
described may be regarded as the rudiments of the complex central mass in
this species. One of the three alluded to, Ap. plicata, has even longitudinal folds
in the middle part.

It is, however probable, that the remarkable structure of this species may
render necessary the establishment of a new genus, a step which I do not venture
to take without farther inquiry.

This form, like the preceding one, first caught my eye in the Glenshira Sand,
where I could find, however, only detached segments, and one half frustule. Not
being able, from these, to understand the structure, and not, indeed, perceiving the

NEW FORMS OF MARIME DIATOMACE. 509

connection between the segments and the half frustule, which only showed the
backs of the segments, I postponed it with other forms, all of which I have now
been able to establish as species. I found the present species tolerably frequent
in Mr Mites’s Corallina gathering, in which detached segments are much com-
moner than the entire frustules.

We shall see, farther on, that a similar structure prevails in a numerous sec-
tion of Amphorz, a few of which were described in my last paper on the Glen-
shira Sand.

GROUP VI.

AMPHORZ.

The new forms of this genus in these materials are very numerous, since,
in addition to almost all those (ten in number) which I had described in the
Glenshira Sand, they have yielded about 32 additional undescribed species. And
as I have again to describe and figure four of the Glenshira species, which are
now better known, there are in all, 36 species of Amphorze to be described and
figured. As the whole of the British species figured in the Synopsis of Professor
SmiTH amounted only to eight, it appears that the Glenshira Sand, and the Clyde
and Loch Fine dredgings, or the latter alone, without the sand, have yielded a_
five-fold addition to the British forms of this genus. This may serve to show
what stores of undescribed forms are yet to be found in our estuaries; for all
these have been obtained from two localities, namely, Lamlash Bay and the
upper part of Loch Fine, just below Inveraray.

The remarkable group of complex Amphoree, to which I have lately directed
attention, and of which the first known example was A. costaia, Sm., though the
peculiarity of its structure seems to have been overlooked, has now become so
large (one-half of the species here described belonging to it) that it is necessary to
subdivide the genus. I shall, therefore describe the Amphorz in two sub-groups,
viz., A. Simple, and B. Complex Amphore.

(Since this paper was read, I have ascertained that two of the Amphore in
the following list of simple species, namely, A. monilifera, and A. spectabilis, be-
long to the complex division. The latter is indeed one of the most curious of the

complex Amphore.)
A. Simple Amphore.

63. csi vi turgida, n. sp. 73. ames pellucida, n. sp.
64. nana, n. sp. 74. levis, n. sp.
65. ... macilenta, n. sp. 75. ... exigua, n. sp.
66. .. angusta, n. sp. WE. ... dubia, n. sp.
67. ... binodis, n. sp. We ... truncata, n. sp.
68. ... ventricosa, n. sp. 78. ... oblonga, n. sp.
69. ...Mmonilifera, n. sp., @ 79. .. Tobusta, n. sp.
70. ... lineata, n. sp. 80. ... spectabilis, n. sp.
ale ... _Ergadensis, n. sp. tol. ..._ Proteus, n. sp.
72. ... levissima, n, sp.

6x

VOL. XXI. PART IV.

510 PROFESSOR GREGORY ON

63. Amphora turgida, nu. sp. Pl. XII, fig. 63. Form nearly orbicular, with
short, square, produced apices. Detached valves, nearly semicircular, with the
vertical margin straight and the extremities capitate. Nodule conspicuous.
Leneth from 0-001" to 000°2"; breadth 0-008" to 0:0015’. Valve marked with
somewhat coarse radiate striz. Striz 24 in 0-001’.

This little form occurs in Lamlash Bay, but it is more frequent in one of the
Loch Fine dredgings, which, though stony and unpromising in aspect, is yet sin-
gularly rich in undescribed species, and especially in Amphorz. The detached
valves or halves of this species, which are like small and very convex Cymbelle,
are much more frequent than the entire frustule.

64. Amphora nana, n.sp. Pl. XIL, fig. 64. Form a narrow, linear-elliptic.
Inner lines lying very near the ventral margin of valves, and nearly straight.
Nodules small; near the ventral margin. Rectangular middle space very
narrow. Length 0-001" to 0:0016’; breadth 0:0004’ to 0:0005’. Strize about 50
in 0-001’.

This small species occurs with the last, and is tolerably frequent.

65. Amphora macilenta, n.sp. Pl. XIL, fig. 65. Form elliptic, long and narrow,
contracting towards the ends, which are again slightly expanded, and terminate so
that it has very short, square, produced ends. Valves very slender, arcuate on
dorsal margin, straight on ventral. Middle space narrow, with a strong median
line. Length 0-0018’ to 0:0022"; breadth of entire frustule 0:0005’ to 0:00086".
Strize parallel, rather coarse, about 30 in 0-001’.

This species occurs with the two preceding, and is not at all unfrequent.

66. Amphora angusta, n. sp. Pl. XIL, fig. 66. Form nearly rectangular, or
rather linear-elliptic, narrow, truncate at the ends, so as to form a slender and
somewhat elegant barrel shape. The inner curve-lines arise in each half or
valve from the outer angle, and meet in a nodule situated half-way across the
valve. Both valves are transversely striated across, up to the narrow rectangu-
lar space in the middle. Length 0:0015"; breadth of entire frustule 00004".
Strize fine, about 44 in 0:001’.

This species occurs with the preceding ones, chiefly in the Loch Fine dredg-
ing above specified, where it is not very rare.

67. Amphora binodis,n. sp. PI. XIL., fig. 67. Form linear, with rounded
apices, and two expansions half-way between the middle and the ends, between
which it is deeply constricted. Length from 0-00175’ to 0-002’; greatest breadth
about 0:0005"; breadth of narrow parts 0:0003". Rectangular middle space nar-
row. The detached halves or valves, having the ventral margin straight, and two
large rounded expansions, while the ends are linear, much resemble the frus-
tules of Hunotia Camelus, as described by Professor SmirH in vol. ii. of his Sy-
nopsis, and figured by Dr GreviLLE in the Annals of Natural History; but the
expansions are smaller and more rounded than in #. Camelus. The inner lines

NEW FORMS OF MARINE DIATOMACE. 511

run nearly parallel to the outer margin of the valve, but are less curved, and
generally obscure. Strize transverse, obscure, about 30 in 0-001".

This very curious little form occurs by no means unfrequently in Professor ALL-
MAN’s dredging from Lamlash Bay, and more sparingly in the Loch Fine dredg-
ing alluded to under A. twrgida. The resemblance of the detached valves to Lu-
notia Camelus has been mentioned. The entire frustule also resembles amini a-
ture of A. angularis, Greg., figured by me in my first paper on the Glenshira Sand.
(See Micr. Jour., vol. iii., pl. iv., fig. 6.) But besides the much smaller size of
A. binodis, the expansions in A. angularis are more angular; indeed, the figure.
represents them less so than they are; and the striation of A. angularis is not
only distinct, but very much coarser, so that the whole aspect of the two forms
is different.

68. Amphora ventricosa, n. sp. Pl. XIL., fig. 68 and 686. Form linear-lan-
ceolate, with obtuse apices, more or less expanded in the middle. Valves long,
very slender, arcuate, with acute ends, marked with somewhat coarse transverse
strie. Length from 0:0023" to 0:0035"; greatest breadth at the expansion in the
middle 0-005” to 0:008". Inner lines generally obscure, but in some cases well
seen. They arise from the inner angle of the valve, pass rapidly across, and, as
shown in fig. 68 6, sometimes extend beyond the outer margin; then suddenly
bend inwards to meet the obscure nodule near the inner margin. Rectangular
middle space narrow. Strize strong, about 22 in 0-001” ; conspicuous.

This pretty and interesting species occurs not unfrequently both in Professor
ALLMAN’s dredging from Lamlash Bay, and in the Loch Fine one so often alluded
to above. The detached valves resemble a very long and slender Cymbella, as
may be seen in fig. 68, in which the form of the valve is plainly seen on each
side of the frustule. By focussing, a transverse bar, or elongated nodule, may
be seen in the middle of the valve; but it is obscured by the strise, when they
are in focus.

69. Amphora monilifera, nu. sp. P). XII, fig. 69. Form elliptic, slightly re-
curved at the apices, which form very short produced extremities. The recurved
ends of the valves do not meet, and the space between them is filled up by a
transverse curve-line. Valves arcuate, very convex on dorsal margin, with re-
curved ends. Nodules on the ventral margin. Between the valves the frustule
is marked by three to five longitudinal rows of distant round granules, giving
to it a dotted aspect. If there be transverse strize, they are very obscure. Length
from 0:0017’ to 0:0026’; breadth from 0:0008’ to 0:0011’.

This pretty and well-marked species is tolerably frequent in the two dredg-
ings mentioned under the last form, but chiefly in that from Lamlash Bay. It
occurs also very sparingly in the Glenshira Sand, as may be seen by referring to
my last plate (7rans. Mic. Soc., vol. v., pl. i., fig. 53). I had figured, from that
deposit, an imperfect specimen, which at first I took for an Amphora, but subse-

512 PROFESSOR GREGORY ON

quently supposed to be possibly not Diatomaceous. The Lamlash Bay dredging
soon cleared up this point, and established it as a distinct species of Amphora.

(Since the preceding description was written, I have ascertained that this
species belongs to the complex group. Like the other complex species, it is formed
of a number of Cymbelloid segments, arranged like the segments of a melon, as
will be more particularly described farther on, in some of the other species. The
convergent longitudinal lines of dots prove to be the dotted backs of the central
segments. I have not been able to find a detached segment, the frustule being
usually entire, so that I cannot give a figure of the segment. I can see, however,
that it has the form of a Cymbella.)

70. Amphora lineata, n. sp. Pl. XIL, fig. 70. Form elliptic or elliptic-lanceo-
late, with short, produced apices, which are truncate. The valves are slender,
arcuate on the dorsal, straight on the ventral margin. The nodules lie in the
middle point of two strong lines, slightly curved, within the ventral margin.
Outside of the nodule is another curve-line, dividing the valve longitudi-
nally into two parts, the outer one being the broader. This outer portion is
marked by fine longitudinal lines, of which there are generally four in each
valve. The rectangular middle space is narrow, and has a sharp line down
the middle. This line, with the inner margins of the valves, the slightly curved
line with the nodule, the line beyond it, and the four exterior lines, give to the
whole a lineate aspect, which is very characteristic. In certain views, the frus-
tule appears lineate uniformly from one side to the other. Length from 0-0022’
to 0°003"; breadth of frustule 00007" to 0:008’. The whole frustule is marked
with transverse parallel strize, which are fine, about 42 in 0-001", and obscure,
except at the margins, where they may generally be distinctly seen. As the lon-
gitudinal lines, however, are much more conspicuous, it is they which charac-
terize the species.

This species is not unfrequent in the dredgings so often mentioned, and occurs
also in the Glenshira Sand. In my last paper on that deposit, I described and
figured it (Zrans. Mic. Soc., vol. v., pl. i. fig. 33). But by some mistake of
mine, the form there figured was either not a characteristic specimen, or, more
probably, a form of A. salina. I have therefore described it anew, and given, in
fig. 70, an accurate representation of a very frequent size and shape of this
species.

71. Amphora Ergadensis,* n. sp. Pl. XII., fig. 71. Form elliptic-lanceolate,
narrow, with truncate apices, which are very slightly expanded. Valves in ap-
position, or nearly so, long, slender; the inner lines, on which lie the conspicuous
central nodules, forming one gentle curve from one end of each valve to the other.
Length about 0:0035"; breadth in the middle 0:00075".. The valves are marked
by strong and conspicuous transverse strice, about 24 in 0-001".

* From Ergadia, Argyll.

NEW FORMS OF MARINE DIATOMACE. 513

This form, like most of the preceding Amphore, occurs both in Lamlash Bay
and in Loch Fine; but it is not so frequent as most of the others. It is conspi-
cuous from its length.

72. Amphora levissima, n. sp. Pl. XIL., fig. 72. Form elliptic, rather nar-
row, ends subtruncate. Aspect remarkably hyaline. Length 0:0025’ to 0-003’;
breadth 0:0009". The inner lines in each valve rise from the inner angles, bend
suddenly outwards for a short distance, then gently inward to the nodule, leaving
a very narrow inner compartment at each end. The middle of each valve is tra-
versed by a strong bar or elongated nodule. The valves are transversely striated,
but the striz are so fine, and the valves so hyaline, that the striation has not
yet been perfectly resolved.

This delicate species is not very rare in the Loch Fine dredging noticed under
A. turgida as rich in Amphoree. But the detached valves are much more fre-
quent than the entire form. These detached valves have a resemblance in form
to the valve of A. elegans, figured in my last paper on the Glenshira Sand
(Trans. Mic. Soc., vol. v., pl. i., fig. 30). But A. elegans is a considerably larger
form, and not particularly hyaline; while its strice are much less fine, and thus
easily seen. 3

73. Amphora pellucida, n. sp. Pl. XIL., figs. 73 and 736. Form a broad oval.
Length from 0-002" to 0-003"; breadth from 0:0012" to 00018". Valves arcuate,
very convex on the dorsal, slightly concave on the ventral surface. There is
something very peculiar in the aspect of the terminal parts of the inner margins
of the valves, as these coincide with the terminal nodules, which, from the
delicacy and transparency of every other part of the inner margin of the valve,
appear to project like horns, as the nodules not only coincide with the ends of the
inner margin, but are narrow and much elongated. The inner lines follow the
margin for a little, then bend rapidly outwards, and then as rapidly inwards to
the central nodule on the ventral margin. The ventral margin, except at the
nodules, is so hyaline as to be seen only on close inspection, as are also the spaces
lying between it and the inner curve-lines. The space outside of these latter
curve-lines is striated, the strive rather coarse; but the whole is so hyaline, that
the strize are only seen on very close inspection, when they come out plainly.
They are somewhat inclined, thicker and more easily seen at the outer margin,
very delicate and nearly invisible towards the inner one, and about 30 in 0-001’.
There is a narrow, rectangular space between the two valves. Sometimes the
form of the frustule becomes nearly rectangular, but all its other characters
continue as before.

The form of the valves, as well as of the entire frustule, in this species, is some-
what similar to that of A. ovalis. But, not to dwell on the marine habitat of A.
pellucida, its very hyaline aspect, and the singular delicacy of the striee, which are
entire, and, towards the nodule, become so fine as to be hardly visible, effectually

VOL. XXI. PART IV. OY

514 PROFESSOR GREGORY ON

distinguish it from that species, in which the strize are conspicuous and moni-
liform.

This species is not unfrequent in the Loch Fine dredging mentioned under 4.
turgida. \t has some resemblance, in the form of the valves, to A. incurva, Greg.
figured in my first paper on the Glenshira Sand (See Mic. Jour., vol. iii., pl. iv.
fig. 5). But in A. zncurva the striation is conspicuous, not hyaline, and the form
of the valve is more elongated, and less projecting at the extremities. I am not
yet acquainted with the entire frustule of A. incurva.

74. Amphora levis,n. sp. Pl. XIL, figs. 74, 74 6, and 74 c. Form of frustule
rectangular, slightly incurved in the middle, sometimes with the ends rounded,
but more commonly with nearly square ends. Length from 0:0017’ to 0-003’;
breadth from 0:0007’ to 0°0012”.. Aspect very hyaline. In each valve the inner
curve line, rising from the inner angle of the valve, and following the margin out-
wards, bends inwards again in a long graceful curve to the central nodule placed
just within the ventral margin. The nodule extends asa strong bar across the
middle of the valve. The outer compartments are transversely striated, but the
strize are very fine, about 60 in 0-001", very hyaline, and hardly to be seen with a
power of 400.

I have added, in fig. 74 d, the figure of a fine Amphora, which probably be-
longs to this species. It is remarkable for the fact, that the curve line coincides
with the outer margin till very near the middle, where it bends inwards to the
nodule. There are also four longitudinal lines at considerable and equal distances.
In this specimen, I have not seen the strize as in the others; but believing it to
be of the same species, I give the figure under the head A. /evis.

This species occurs with the last, and is more frequent, though by no means
abundant. It frequently happens, as in one of the figures, that the valves are in
apposition ; and as this occurs in long examples, these become proportionally
narrow.

75. Amphora exigua,n. sp. Pl. XUL, fig. 75. Form linear-elliptic, narrow,
with somewhat obtuse ends. Length from 0°0015" to 0°0022’; greatest breadth
about 0:00035". The valves are transversely striated, the strize being strongest
at the margin. Strize about 28 in 0-001".

This little form occurs, scattered, both in Lamlash Bay and Loch Fine. In
size and form it approaches nearest to A. lineata (Pl. XII. fig. 70); but its mark-
ings are totally different. It has no striking characters, but I cannot refer it to
the same species with any of the small Amphore I have here described.

76. Amphora dubia, n. sp. Pl. XIIL, fig. 76. Form of entire frustule oval,
flattened, or even a little incurved, on the sides. The valves are concave in the
middle of the ventral margin ; so that as they are in apposition, there is a longish
rhombic opening in the middle, between them. They also diverge a little at the
apices. Within each valve is a faint line, nearly parallel to the outer margin,

a

“ee

NEW FORMS OF MARINE DIATOMACEX. 515

but lying nearer to the inner margin. On these lines are faint nodules, while at
the middle of the inner margin there are distinct nodules. Length 0:0025’:
breadth 0:0011". The whole is marked by transverse strize, which also traverse
the openings between the valves, in which openings a median line is also visible.
Strize fine, subdistant, about 24 in 0-001". The divergent extremities are joined
by a convex curve line.

This very peculiar species occurs, but very sparingly, in Lamlash Bay. It has
some analogy with A. marina, a form lately figured by Professor Smrru, in the
Annals of Natural History (January 1857, vol. xix., pl. i, fig. 2.) But besides
the coarser striation and distinct nodules of A. dubia, Professor Smiru describes A.
marina as so much resembling A. afinis, that it has been confounded with that
species on our coasts. Now A. dubia has no resemblance whatever to A. afinis,
nor indeed to any other known species; so that I have some doubts as to its being
really an Amphora. The figures of A. marina given by Professor SmirH are not
satisfactory, for they do not at all resemble A. affnis.

77. Amphora truncata, n. sp. Pl. XTIL., fig.77. Form of frustule slightly barrel-
shaped, broad, with truncate ends. Length about 0-0028"; breadth about 0-0017’.
Valves arcuate on dorsal, straight on ventral margin. Inner curve lines arise
from the terminal margin, and bend gently inwards to a small nodule, rather
nearer the inner than the outer margins. Inner margin of valve marked by a lon-
gitudinal line of short transverse striz. In the rectangular space between the two
valves, which is broad, are two similar longitudinal lines of short strize, near to,
and parallel to those just mentioned, and between the two last-named lines or
bars are traces of others. Valves transversely striated, but the striz are more
conspicuous on a band at the outer margin, than elsewhere. So that the frustule
appears, at least m a certain focus, marked with longitudinal striated bands,
formed of short strive.

This species is not very rare, in either of the two gatherings so often named
in connection with Amphorze. It frequently happens, that the line joining the
ends of the valves appears to be interrupted in the middle. But by careful focus-
sing it may be seen.

The appearance of longitudinal striated bands on the middle part of the frus-
tule seems to indicate a tendency in this species to the complex structure. In-
deed, among the complex species there is one, A. guadrata, which has consider-
able analogy with the present form.

78. Amphora oblonga, n. sp. Pl. XIIL., figs. 78, and 78 6. Form linear elliptic,
rather broad, the ends obtusely acuminate. Length from 0:0034" to 0-004’:
breadth from 0:001" to 00014". The inner curve lines are strong and much
curved, but they keep unusually near the outer margin of the valve, only in the
middle projecting rather more than half way across. The central nodules, which
are conspicuous, are situated outside of the curve lines, and nearer to the outer

516 PROFESSOR GREGORY ON

margin. Valves transversely striated. Striz about 24 in 0-001’, conspicuous.
The portion of the valve outside of the curve line seems to be in a plane different
from that of the inner portions, and the striz on the latter are radiate.

This well-marked and conspicuous species. remarkable for the position of the
central nodules, is by no means rare in one of the Loch Fine dredgings, in which,
except this form, Campylodiscus angularis, and C’. Ralfsii, but few forms are found.
It occurs more sparingly in some of the other dredgings.

79. Amphora robusta, n. sp. Pl. XIIL., figs. 79, 79 6, and 79 c. Form of frustule
a broad oval with subtruncate extremities. Length from 0:0033’ to 0-0048", occa-
sionally even as much as 0°006. Breadth from 0:0018" to 0:0024". Valves arcuate,
with the ends more or less obtuse; ventral margin straight or slightly concave.
Inner curve lines very sharp and strong, rise from the inner angles, pass outwards,
without reaching the outer margin, and bend suddenly inwards to the central
nodules, which are within the ventral margin, by one-fifth of the width of the valve.
In some specimens, or perhaps in a certain focus, the points where the two curve
lines meet in the middle is on the inner side of a straight line, apparently forming
the inner margin of the valve, so that a small blank triangular space is included
between that straight line and the ends of the two curve lines. This produces a
very peculiar aspect. Frustule thick, marked with strong striz, which on the
compartments outside the curve lines are transverse, but on the inner terminal
compartments are somewhat radiate. Strice subdistant, moniliform, about 16 in
0-001". Figs. 79 6, and 79 c, represent two valves, in one of which the curve lines
are seen, while it is evident that the inner compartments are in a different plane
from the outer one. The other shows the entire valve viewed in a different focus,
in which the strize appear all in one plane.

This fine form, conspicuous for its size and the stoutness of its aspect, is not
rare in the Loch Fine dredging mentioned under A. twrgida, and occurs also in
Lamlash Bay.

80. Amphora spectabilis, n. sp. Pl. XIIL., figs. 80, 80 6, and 80¢. Form nearly ~

rectangular, broad, with rounded angles; occasionally sub-elliptic. Length from
0:003" to 0°0047"; breadth from 0:002” to 0:0025". The inner curve lines bend in-
wards from the outer margin very nearly to the inner margin of the valve, divid-
ing the valve into a middle outer compartment, and two terminal inner ones. The
detached valve has prominent obtuse rostra or beaks, not seen in the entire form.
Outer compartment transversely striated, the striation being very coarse; inner
compartments marked with radiate strie, which are much finer. Aspect of the
whole form soft and indistinct, so that in general only the marginal ends of the
strize in the outer compartments are easily seen, these strize being thicker at that
end, and the frustule very convex. Even at the margin they are not sharp but
softened. Strize in the outer compartment 14 to 16 in 0-001": in the inner ones,
26 in 0001", and very obscure. As in the last species, and indeed in many Am-

NEW FORMS OF MARINE DIATOMACEA. 517

phore, the inner compartments seem to be in a different plane from the outer
ones. This species exhibits two frequent varieties, both smaller than the typical
form, which are figured (figs. 80 6, and 80c). One is long and narrow, its length
being 0:0032", its breadth hardly 0:0008". The other is short and broad; its length
being 0:002’, and its breadth 0-001". Both have the soft, hazy, indistinct aspect
of the larger form, and both, when carefully examined, exhibit the same characters,
except that the striation is perhaps somewhat finer.

(Since the above was written, I have found that this species not only belongs
to the complex group, but is one of the most interesting forms in that group. As
will be seen in the descriptions of various complex Amphore, the complex struc-
ture is only seen in one focus, while in another, the frustule exhibits the charac-
ters of a simple Amphora. This is peculiarly the case in A. spectabilis. The
simple view, shown in fig. 80, is so thoroughly simple, that it never occurred to
me that it could possibly conceal a second and more complex structure. But
when I happened to examine, under a rather high power, and with oblique
light, a frustule well placed for bringing out this structure, I detected the appear-
ance shown in fig. 80d. In this case, the coarse transverse strize of the middle.
part, as seen in fig. 80, were still traceable, at the margin only, on one side, be-
cause the frustule did not lie quite flat. In other examples, no such traces are
visible on the complex view, although in general the very strong and elongated
central nodules shine through. In fig. 80d, it will be seen that the whole frus-
tule is composed of parallel, longitudinal, very slightly convergent bars, with a
narrow sulcus between each two bars. These bars are transversely striated, and
the strize, though much finer than even those of the inner and terminal com-
partments of the valves, are yet quite distinctly seen, even more so than the
others, being apparently free from the haziness above alluded to. Striz of the
bars, in this view, about 50 in 0°001".

In this remarkable form we have the unusual occurrence of three distinct sys-
tems of striation; 1st, The coarse, soft, and hazy transverse strize of the outer and
middle compartments of each valve, on the simple view, fig. 80; 2d/y, On the same
view, the finer and radiate strize of the two terminal inner compartments of each
valve, which lie in a plane inclined to that of the middle compartments; and, 3dly,
The still finer and parallel strize crossing the longitudinal bands, in the complex
view, fig. 80 d, which lie again ina different plane. The frustule is also remarkable
for its convexity, which is probably the cause, or one chief cause, of the indis-
tinctness of the markings on the simple view.)

This beautiful species is tolerably frequent in Professor ALLMAN’s dredging
from Lamlash Bay, and in one from Loch Fine, less so in the other dredgings.
The short variety is even more frequent than the typical form. The species
has some resemblance to the preceding one in general form and coarseness of
striation. But it is at once recognised by its hazy indistinct aspect, by the finer

VOL. XXI. PART Iv. 6 Z

518 PROFESSOR GREGORY ON

striation on the inner compartments, by the beaked form of the detached valves,
and finally, by its varieties. (Its complex structure, and its three systems of
strie, are even more decisive characters.)

81. Amphora Proteus, n. sp., Pl. XIII, figs. 81,816; 81¢; 81d; and 81e.
Form very variable, obtuse lanceolate, elliptical, barrel-shaped, broad and trun-
cate, long and narrow, &c. It has usually the rectangular space between the valves,
but sometimes the valves are in apposition, and then resemble twin frustules of
Cymbella. Some of these modifications are figured. The size also varies prodigiously.
Length from 0:0015" to 0-006"; breadth from 0:0013 to 0-0024’. The broadest ex-
amples are generally short. Valves acute, sometimes with arcuate, at other times
with obtuse apices. Inner curve lines and nodules strongly marked, and inner
compartments of the valve in a different plane from the outer ones. There are two
peculiarities which are found in all specimens, from the smallest to the largest. When
the outer compartment is in focus, and its strize conspicuous, the strize of the inner
compartments appear in narrow lines or bars, separated by white longitudinal
lines or raphes; and the transverse strize, which are finely moniliform, are, espe-
cially, in a certain focus, traversed by longitudinal wavy lines or strize, produced
by the circumstance that the granules of contiguous transverse striz are not
placed exactly opposite each other. In figs. 81 and 81 0, the same specimen, a
long one, is shown as it is seen in two different foci, one of which brings out the
curve lines and nodules, the other the transverse strize, which extend across the
whole valve. These striz are about 22 in 0:001"; but in regard to the number of
striz there are very great variations in this species, as I have shown, in former
papers, to occur in other species. In some of the smaller specimens the strize are
at least twice as numerous as in some of the larger, and even in the specimens of
equal size they differ in this respect. But in all, the striz exhibit the characters
I have mentioned as peculiar and characteristic.

(I must here state, however, that there are some forms which, for the present,
I include under A. Proteus, respecting which I have great doubts whether they
ought not to form a distinct species. These forms have many characters in com-
mon with A. robusta, but have uniformly a much finer striation, and consequently
a very different aspect.)

This species is very frequent in Lamlash Bay, and also in some of the Loch
Fine dredgings. At first I was quite at a loss with the multitude of forms agree-
ing in striation, but when I had observed the characters above mentioned, I was
able to trace all these forms into one another by gradual transition. Those here
figured are some of them very different; but intermediate forms occur. One of
the figures represents two valves in apposition, which I suspect to belong to this
species (fig 80, e); but I am not quite certain about that one.

I may here direct attention to the fact, that such a form as that shown in fig.
81 e, resembles closely a twin frustule of a Cymbella or Cocconema. Yet it is con-

NEW FORMS OF MARINE DIATOMACEZ. 519

sidered as only a single frustule, while the Cymbella or Cocconema would be called
a double one.

I confess I feel disposed to consider both in the same light, as double forms.
If that be correct, then what is usually called the valve of an Amphora will be
an entire frustule, and what is usually called the entire frustule (as in figs. 63 to
72, for example) will be considered as two frustules in the act of self-division, but
still united by the connecting membrane.

One reason why I incline to this view is, that what, on this principle, are to
be called single frustules, which are now regarded as halves or single valves, are
often much more frequent than the entire, or, as I should say, double frustules.
We never see the halves of Naviculze separated in this way. Secondly, Each single
valve, or as I should say frustule, has three nodules; but the entire or double
frustules have six. Jhirdly, In Amphoree, the two halves of the double or entire
frustule are almost always separated by a rectangular space, apparently homo-
logous with the connecting membrane, which is seen in other genera when in a
state of self-division. When this is absent, as in fig. 81 ¢, or in fig. 76, the form
has exactly the appearance of a twin frustule of Cymbella. Lastly, If we regard .
the so-called valves as entire frustules, they become perfectly analogous, in gene-
ral form and structure, to Cymbellz or Cocconemata; and we shall find, in the
remarkable group of Complex Amphore, next to be described, that the segments
in many species, indeed in most, have a still greater resemblance to Cymbelle or
Cocconemata.

Let us now consider that group.

B. Complex Amphore.
Of this sub-group, as I have already stated, there are, in these materials, as many
as of the simple group just described. These species are as follows :—

82. joEheS lyrata, n. sp. 92. og sulcata, Breb.

83. Milesiana, n. sp. 93. acuta, n. sp.

84. ... elongata, n. sp. | 94. ... erassa, Greg.

85. ... quadrata, n. sp. 95. pi pusilla, n. sp.

86. =. | -eX€lsa, 1. Sp. 96. ... granulata, n. sp.
87. ,20)) mobilis, n,'sp., G. 97. ... eymbifera, n. sp.
88. +» Arcus, Greg. 98. ... proboscidea, n. sp.
89. ... Grevilliana, Greg. | 99. ... _costata, Sm.

90. .-. complexa, n. sp. 100. ... bacillaris, n. sp.
91. ... fasciata, n. sp.

The first species of this group which was figured was A. costata,Sm. But the
remarkable peculiarity of its structure was not specially noticed. I subsequently
noticed several species in the Glenshira Sand, in which the complex structure had
attracted my attention, such as A. Arcus, A. Grevilliana, and A. crassa, which
I described and figured. I also pointed out that the same structure occurs in
A. costata, Sm. In the new materials, besides acquiring a more accurate know-
ledge of the three new species just named, all of which I here figure a second

520 PROFESSOR GREGORY ON

time, I: have found a considerable number of new species, exhibiting the same pe-
culiarities of structure.

The general character of all these species is, that the frustule is very convex,
and formed, in the first place, of two segments or valves, in shape like Cymbellze
or the halves of simple Amphore, placed opposite each other, as in the simple
species. The middle space between these is, in the next place, covered, to a greater
or less extent, by a complex mass, like that seen in Amphiprora complexa,
(fig. 61), and exhibiting, when the two lateral segments lie flat, a series of con-
vergent longitudinal bars, which are the backs of other segments, grouped like
those of an orange ora melon. The lateral segments exhibit all the characters
of the halves of a simple Amphora; they have the inner curve lines and the no-
dules, in some cases elongated so as to form a cross bar. The segments forming
the central mass appear to have neither curve lines, nor nodules, nor bars. The
lateral segments are transversely striated, and the bars of the central mass, or
backs of the central segments, are frequently also marked by transverse strize ; but
in other cases have much coarser markings, approaching more to the nature of
puncta or granules. In some species again, while the margins of the lateral seg-
ments are very coarsely marked, the backs of the middle segments are much more
finely striated. In general, when the frustule lies so, that the two lateral seg-
ments are flat or nearly so, we see in one focus the lateral segments with their curve
lines and nodules, while in another focus these become invisible, and the conver-
gent bars alone are seen, which in many cases fill up the whole space between the
lateral segments, of which only a part, that nearest the outer margin, can then
be seen. This is shown in several of the figures.

This structure is so peculiar, that it seems as if it would be desirable to estab-
lish a new genus for the reception of these forms. But the form of the seg-
ments is so exactly that of the valves (or frustules) of simple Amphore, and
even the entire complex forms, in a certain focus, are so like the others, that I
think it will be sufficient to make a sub-genus for the complex forms.

I have already mentioned that some of these forms occur in the Glenshira
Sand ; others, as well as these, are found in the dredgings from Lamlash Bay.
But by far the larger part of the complex species here described are to be found
in that one Loch Fine dredging spoken of under A. turgida, as being rich in Am- —
phore. Of the above list, thirteen species at least, along with A. costata, besides
fourteen or fifteen of the simple group, occur in this one dredging, and several
of these are found in it alone. It will be unnecessary to repeat this in detail for
each species; and I shall briefly refer to Loch Fine as the locality of the species
here alluded to as occurring in that particular dredging.

82. Amphora lyrata, n. sp. Pl. XIIL., fig. 82. Form doubly lyrate, with
truncate ends, and a notch in the middle, on each side, where the two lyrate
halves meet base to base. The lateral segments have each a strong bar or elon-

NEW FORMS OF MARINE DIATOMACEZ. 521

gated nodule in the middle. Bars between the lateral segments four or five.
Length 0:0011”; breadth 000075’. The whole form is transversely striated ;
strize distinct, about 36 in 0-001’.

This pretty little form is not very rare in the Loch Fine dredging above men-
tioned, as containing most of the complex Amphore. I have seen it also in
Lamlash Bay.

83. Amphora Milesiana, n. sp. Pl. XIIL., fig. 83. Form nearly rectangular,
with a constriction in the middle, and subtruncate ends. The sides are very
slightly convex. There are several longitudinal bars between the lateral seg-
ments. Length 0:0023"; breadth 0-001". The whole is transversely striated ;
striz about 28 in 0-001", conspicuous.

This species occurs with the last, both in Loch Fine and in Lamlash Bay.

84. Amphora elongata, n. sp. Pl. XIIL., fig. 84. Form elliptic lanceolate ;
long, narrow, with truncate extremities. Length 0:0044"; breadth 0-0011’ ;
Lateral segments very narrow; curve lines very near the outer margin. There
are six bars in the middle, convergent on the ends. Strize conspicuous, trans-
verse, about 26 in 0-001’.

This species occurs both in Lamlash Bay and in Loch Fine. It is not frequent,
nor yet very scarce.

85. Amphora quadrata,n.sp. Pl. XIIL., fig. 85. Form nearly rectangular ;
the sides slightly convex, broad, ends truncated, as in A. truncata. Length
about 0:0027"; breadth about 0:0018". Lateral segments arcuate on the dorsal,
straight on the ventral margin. Between them are about six broad vertical stri-
ated bars, which are not, as in the preceding forms, in apposition, but which are
somewhat distant, being separated by narrow raphes. The structure, therefore,
differs in some respects from that of the other complex species. The lateral seg-
ments and the vertical bars are transversely striated; strize about 34 in 0-001’.

This species occurs both in Lamlash Bay and in Loch Fine, and is not very
rare.

86. Amphora excisa,n. sp. Pl. XIIL., fig. 86. Form rectangular. The curve
line in each lateral segment keeps near the outer margin, except in the middle,
where it bends inward to a nodule; but outside of this nodule is another, larger
and more conspicuous, situated on the outer margin, which appears deeply
notched at this point. Length 0:0025’ to 0-004’; breadth 0-0015" to 0:0018’.
There are a number of longitudinal bars, convergent at the ends. The whole form
is hyaline, and marked with very fine transverse strice, which are best seen,
though with difficulty, at the outer margin. Strize about 52 in 0-001’.

This fine species occurs in Lamlash Bay, where it is not unfrequent. It is also
found more sparingly in Loch Fine.

87. Amphora nobilis, n. sp. Pl. XIIL, fig. 87. Form barrel-shaped, broad,
ends truncate. Length from 0-003" to 0:0045"; breadth, 0:0013 to 0:0028". La-

VOL. XXI. PART IV. ux

522 PROFESSOR GREGORY ON

teral segments arcuate, ends acute, inner curve-lines strongly curved, nodule
elongated into a transverse bar. The converging bars in the middle are numerous,
in apposition, and the whole frustule very hyaline. It is marked by fine trans-
verse striz, easily seen on the lateral segments, and which may also be traced, by
careful manipulation, across the whole frustule. Strize about 40 in 0-001’.

I first observed this fine and conspicuous form in the Glenshira Sand, but
postponed the description of it that | might examine it farther. I have found it
more frequently in Lamlash Bay and in Loch Fine.

88. Amphora Arcus, Greg. Pl. XIII., fig. 88. Form of entire frustule barrel-
shaped, ends truncate. Segments arcuate, sub-apiculate, marked by coarse moni-
liform strize, which are also seen over the entire form. Length from 0:0035" to
00045"; breadth about 0-002." Strize 16 or 18 in 0-001". The longitudinal bars
in the middle between the lateral segments are about 16 or 17, closely set, and we
can see that they are segments seen edgewise.

This fine form was rather frequent in the Glenshira Sand, but was only then
known in the shape of detached segments, two of which I figured in my first paper
on that deposit (Wie. Jour., vol. iii., pl. iv., fig. 4), without at that time under-
standing its real structure. Subsequently I recognised the entire frustule in the
Glenshira Sand, and also in the dredgings from Lamlash Bay. In my third paper
I figured an imperfect specimen (7Z'rans. Mic. Soc., vol. v., pl.i., fig. 37), and Inow
give a more perfect one, which shows that it really belongs to the complex group.
See fig. 88.

89. Amphora Grevilliana, Greg. Pl. XIIL, fig. 89. Form of entire frustule
nearly oval, broad, slightly truncate at the extremities, which are broad, the line
joining the apices of the lateral segments being concave, so that a short process
stands out at each side. Length about 0-006"; breadth about 0-002’. In the spe-
cimen figured (fig. 89) the form of the lateral segments is perfectly seen, probably
because the frustule is viewed from the flat side, as we view an orange cut in
half from the cut side. These segments are precisely like that figured in my last
plate from the Glenshira Sand (7rans. Mic. Soc., vol. v., pl. i., fig. 36*). They
are broad, arcuate, with somewhat acute rostra, and three curve-lines on their
surface, which are peculiar to this species. They are marked with strong trans-
verse moniliform strize. Strize about 28 in 0-001". Between the lateral segments
are five or six convergent bars, which are the backs of other segments, and which
are in apposition, except at the ends, where they diverge a little, from their
apices becoming suddenly narrower.

This fine species occurs both in the Glenshira Sand and Lamlash Bay. But
the entire frustule given under this name in the plate just referred to (at fig. 36)
does not belong to this species, as may be seen at once by comparing it with fig.
89, and by the form of its segments, as seen in that figure. The segment in that
plate, fig. 36*, is correct, as above stated.

Pj ae aie it
ee te ea? ee

NEW FORMS OF MARINE DIATOMACEZ. 923

The form figured in my last plate, at fig. 36, as the entire A. Grevilliana, is a
new species, to which I now proceed.

90. Amphora fasciata, n. sp. Pl. XIT., fig. 90. Form of entire frustule barrel-
shaped, that is, gently convex on the sides, broadly truncate on the ends. The
form of the lateral segments, as well as that of the inner curve-lines, is well
seen at the sides. Length about 0-005"; greatest breadth about 0:0023". Be-
tween the lateral segments are seven or eight converging bars, separated by
very narrow raphes; these are the backs of other segments. The detached seg-
ments are arcuate on the dorsal margin, nearly straight on the ventral margin,
with acute ends. They have only one curve-line, bending forward in the
middle to the nodule, which is near the ventral margin. Striz about 34 in
0-001", conspicuous.

This fine and conspicuous form is not unfrequent in the Glenshira Sand, and
occurs also sparingly in Lamlash Bay and in Loch Fine. Unlike the preceding
one, it is almost always entire.

91. Amphora complexa, n. sp. Pl. XIIL., fig. 91. Form of entire frustule rec-
tangular, with rounded extremities. Length about 0:005"; breadth about 0:0021.’
Lateral segments narrow, with the dorsal margin straight, except near the apices, |
where it bends inwards. Inner line strongly curved to the nodule, which lies close
to the ventral margin. Between the lateral segments are seven longitudinal con-
verging bars, the backs of other segments, which meet on the convex ends, en-
tirely filling them up. These bars are separated by raphes, rather broader than in
the preceding species. The whole form is marked by transverse strize, which are
strong and conspicuous; about 30 in 0-001".

This very fine and conspicuous form, which is evidently nearly related to the
two which precede it, A. Grevilliana and A. fasciata, while yet all these are dis-
tinct, as is seen by the figures, occurs, like the others, both in the Glenshira
Sand and in Lamlash Bay, and is not very rare. For some time I confounded
all these together in the Glenshira Sand, and it was only a careful examination,
especially of the detached segments, which showed me that they were really dif-
ferent species.

92. Amphora sulcata, Bréb., n. sp. Pl. XII, figs. 92 and 926. Form barrel-
shaped, rather broad, ends truncate. Length of frustule 0-0041’; breadth 0-002”.
Lateral segments broad, arcuate; inner lines strongly curved, nodule near ventral
margin. Between the lateral segments—when viewed in a focus which brings out
these segments clearly, as in one of the figures—are seen four or five converging
bars. These bars, and all the lines of the lateral segments, are marked by short,
transverse strize, the rest of the surface being hyaline. In another focus, the
Jateral segments and their curve-lines disappear, and the whole width is taken
up by seven or eight converging bars, which are now separated by very narrow
lines of transverse striz. The whole form is very hyaline and very convex. It

524 PROFESSOR GREGORY ON

is transversely striated; but the strize cannot be traced throughout without alter-
ing the focus. Strize about 38 in 0-001".

This remarkable form was first described by De Bresisson as occurring near
Cherbourg. No form is better adapted to show the structure of a complex Am-
phora, on account of its transparency, and the breadth of the convergent bars.
I have found it in Lamlash Bay, where it is not very frequent; and also sparingly
in Loch Fine. No detached segments have yet occurred.

93. Amphora acuta, n. sp, Pl. XIV., figs. 93 and 936. Form of detached
segment arcuate, dorsal margin convex; in some examples with a slight inflec-
tion just before the extremities; ventral margin straight, or slightly concave,
ends acute. The inner lines are very near the ventral margin, and almost ex-
actly parallel to it, but sometimes a little incurved, except in the middle,
where the nodule meets them. Nodule elongated into a strong transverse
bar. Length of segment 0°0035" to 00055"; breadth of it 0°00075". The seg-
ments are marked by transverse striz, about 36 in 0-001", which are distinctly
moniliform.

I have not yet seen the entire frustule ; but it is no doubt complex, for I found
a good many half-frustules, as it were, formed of segments lying one over the
other, to the extent of five or six. Sometimes no cross bar is seen, probably be-
cause the cross bar is only found on the lateral segments, which may have be-
come detached, and left the middle ones by themselves. One figure shows a group
or pack of segments.

This species occurs in Lamlash Bay, but is more frequent in Loch Fine. It
is probable that the entire frustule will somewhat resemble A. nobilis in form,
but not in its hyaline aspect. On comparing the segments of A. acuta with those
of A. nobilis, as seen in the entire frustule, the curve lines in the latter are seen
to be very deeply curved, and to be much farther from the inner margin of the
segment, whereas the inner lines in the segments of A. acuta are straight, or very
nearly so, and close to the ventral margin. In A. acuta, the striz, though not
coarse, are strongly moniliform, while the strize of A. nobilis are much finer. Yet
it is probable that these two species are related.

(I have very recently observed two specimens, apparently of A. acuta, in which
two segments are placed opposite, and close to each other. I suppose this view
to represent the flat side of the frustule, or the half frustule, like a cut orange, as
in the figure of A. Grevilliana, fig. 89. But in these specimens of A. acuta, the
two lateral segments are in apposition. )

94. Amphora crassa, Greg. PI. XIV., figs. 94, 946, 94¢,94d. Form of frus-
tule rectangular, broad, with rounded ends. Length from 0-0025" to 0-004’;
breadth from 00008" to 0:0013”. Lateral segments linear, from 0:0005" to 0:00075”
in breadth, straight, or very slightly incurved on the dorsal margin, which, at
the apices, bends inwards, forming short, rounded beaks. Sometimes, as in one

NEW FORMS OF MARINE DIATOMACEZ. 525

of the figures, the dorsal margin is convex. Ventral margin of segments undu-
lated. The inner curve lines arise from the point of the beaks, run a little
outwards, then inwards to the nodule, placed very near the ventral margin.
Markings entire, coarse, subdistant. Strize about 12 in 0-°001". Between the la-
teral segments are from five to eight convergent bars, marked with the same
subdistant, entire striz. In one focus, not here figured, nothing is seen but bars
from one side to the other, which are thus eight or nine in number.

This very pretty and interesting species occurs in the Glenshira Sand, but the
figure given of it in my last plate (Z’rans. Mic. Soc., vol. v., pl. i., fig. 35), is not,
at all events, the usual form. In that figure the markings are too close, and it
may possibly represent a different species. Indeed, I have some reason to think
that there are two species which resemble each other in several points. But I
have not yet ascertained this to be the case. I have found the form now figured,
which is the true A. crassa, more frequent in Lamlash Bay, where, also, I have
observed the detached segments, previously unknown to me, and which, as may
be seen, are very peculiar. It occurs also in Loch Fine, though less frequently.

95. Amphora pusilla, n. sp. Pl. XIV., figs. 95 and 95 6. Form linear, with
rounded ends. Length from 0-0014’ to 0:0021"; breadth 0:0004’ to 0-0006’. :
Lateral segments very narrow, dorsal margin straight, except at the ends, nodule
not far from dorsal margin, inner curve line also near it; striation conspicuous.
Between the lateral segments are five or six narrow bars, separated by very fine
sharp lines, and marked by subdistant granules or very short striz. Strize about
24 in 0-001’, very strong at the margins of the frustule.

This little form is not very rare in the Loch Fine dredging, so often referred to ;
and occurs also, though more sparingly, in Lamlash Bay. In general aspect, it
resembles a delicate miniature copy of the preceding species; but the form of the
segments, the curve lines, and the striation, are all totally distinct.

96. Amphora granulata,n.sp. Pl. XIV., figs. 96; 966; 96 ¢; 96d; 96e; and
96 7. Form of frustule linear, broad, with slightly convex sides, and truncate ex-
tremities. Length from 0-0017’ to 0-003"; breadth 0:0008" to 0-0013". Lateral
segments slightly arcuate on the dorsal margin, which is suddenly narrowed at
the ends; ventral margin quite straight, or slightly concave, apices sub-acute.
Segments marked with fine transverse strize, which are parallel, and from 24 to
36 in 0-001’. Fig. 96 f, represents a detached segment. When the frustule is
so focussed that the lateral segments are distinctly seen, and their strize plainly
resolved, the space between appears nearly blank. But in another focus, the
whole frustule is seen to be made up of about twelve longitudinal bars conver-
gent on the ends, the backs of which are marked by subdistant granules, from
14 to 18 in 0001’. Hence the name. I have figured these two views of each of
two frustules, one short and broad ; the other longer and narrower. One figure,
fig. 95 e, represents a somewhat larger form, which also exhibits granulated bars,

VOL. XXI. PART IV. 73

526 PROFESSOR GREGORY ON

and lateral segments approaching in form to those of A. granulata. But on care-
ful comparison, it seems very doubtful whether this form do not belong to a dif-
ferent species. As I have not yet had time to ascertain this precisely, I give it
here cum nota.

A. granulata is tolerably frequent in the Loch Fine dredging I have named as
being so rich in species of Amphora, especially of complex Amphore. I would
observe that in this form the striation of the lateral segments is finer than that
on the middle bars, whereas in the next species the reverse is the case. A.
granulata sometimes attains a considerably larger size than in the two un-
doubted specimens here figured.

97. Amphora cymbifera, n. sp. Pl. XIV., figs. 97, 97 b, 97 c. Form of frus-
tule elliptic, rather broad, with very short, produced, and truncate apices. Length
0:0025" to 0:0045"; breadth in the middle, 0-0012 to 0:0016". Lateral segments
highly arcuate on the dorsal, almost straight on the ventral margin, the former
being suddenly contracted at the ends, so as to produce round heads, with very
short necks; thus the segments are capitate. Their form is elongated, and the
curve regular and graceful. They are marked by somewhat coarse striae, slightly
inclined. Strize about 22 in 0-001". The nodules are on the inner margin, or
just within it, and the inner lines are parallel to that margin, and close to it.
The segments, when detached, as is seen in one of the figures, exactly resemble
the frustules of an elegant Cymbella. Between the lateral segments lie from five
to seven convergent bars, and, in one focus, the whole frustule is seen to be made
up of these bars (fig. 96 b), which are marked by fine transverse striz, consider-
ably finer than those on the lateral segments, which became stronger and coarser
near the margin, as may be seen by the figures. The bars, as in A. sulcata (fig.
1), appear to be separated by furrows, and in a certain focus these furrows may
be seen marked by lines of short transverse striz. Fig. 96 is the same frustule
as that in 96 6, focussed so as to show the lateral segments. Fig. 96 ¢, is a de-
tached segment.

This fine form is not unfrequent in the Loch Fine dredging above mentioned.
The views of it are so different, according to its position, and the detached seg-
ments are so like Cymbellw, that it was some time before I could see my way
among these forms, especially mixed as they were with frustules and segments
of the preceding, as well as of the next species, which have a similar structure.

98. Amphora proboscidea,n. sp. Pl. XIV., figs. 98; 9856; 98¢; 98d. Form
of frustule nearly rectangular in the middle, contracted near the ends to truncate
extremities. Length from 0-003" to 0005"; breadth from 0-001" to 0:0015". The
longer specimens are narrower than those of middling length. Lateral seg-
ments arcuate on the dorsal, often slightly convex, or undulated, on the ventral
surface, contracted at the ends so as to be capitate, the heads having longer necks
than in the preceding species, which are bent forward at a very obtuse angle,

NEW FORMS OF MARINE DIATOMACEZ. 527

giving to the detached segment a very peculiar character. The segments are
marked by strong, coarse strize, about 20 in 0-001’. In one focus (fig. 97) the
segments are well seen in the frustule; in another, fig. 97 6, the frustule is seen
to consist of 9 or 10 convergent bars, which are coarsely granulate. In fig. 97
the lateral segments are seen to be nearly in apposition, with a narrow space
between them, of varying width, from the undulations of the ventral margin.
The inner line of each lateral segment is very slightly curved; the nodule lies
nearest to the ventral margin. The detached segments, figs. 97 c, and 97 d, are
precisely like Cymbelle, and for a long time I considered them as such, with those
of A. granulata and A. cymbifera. But the view in fig. 97 showed the real
nature of these forms. Want of space alone prevents me from giving figures of the
entire frustule corresponding to the segment in fig.97 d. The reader is requested
to compare fig. 97 with the corresponding view of A. Grevilliana, fig. 89.

This very striking species occurs only in the stony Loch Fine dredging, so often
alluded to, where it is rather frequent, both entire and in detached segments.

99. Amphora costata, Sm. Pl. XIV., fig. 99. This species is described by
Professor SmitH in his Synopsis, vol. i., where the entire frustule, and also a half
frustule, are figured. But little is said of its peculiar structure, and the detached .
segment is not figured. For this reason, and to show the analogy between this
species and the three preceding ones, I have figured a detached segment (fig. 99).
Form of segment highly arcuate, very broad in the middle. Ventral margin
straight, or slightly concave, but often, as in the example figured, which is a
rather small one, with a rounded prominence in the middle close to the nodule.
The ends are capitate. Strize coarse, conspicuous, about 14 or 16 in 0-001’,
thicker and stronger near the dorsal margin. Length from 0:002" to 0:0033’ ;
breadth in the middle 0-0012’ to 0-0016".

It will be seen that in this species also the segment resembles a Cymbella,
although it isa very broad and highly arcuate one. When the segments are
united, as in the entire frustule, it is not easy to see their real characters. The
backs of these segments, or longitudinal bars, are, as in Professor Smiru’s accu-
rate figures, marked by very coarse distant granules, which give no indication of
the peculiar striation of the detached segments. Hence it was very long before
I was able to detect the component parts of the frustule when detached, or to re-
fer the form shown in fig. 99 to A. costata. But some specimens, as in the pre-
ceding species, when carefully focussed, clearly show their true nature.

100. Amphora bacillaris, n. sp. Pl. XIV., figs. 100 and 100 6. Form of frustule
linear, narrow, with somewhat rounded ends, which are subacute. Length about
00017"; breadth about 00003". In one focus it exhibits two lateral portions se-
parated by a middle space, the sides of which are perfectly straight, the ends
beautifully rounded. In another, the whole frustule is seen to be composed of
very narrow bars, separated by very sharp lines, converging on the ends, and

028 PROFESSOR GREGORY ON

marked with small granules. Striation transverse, fine; number of striz not
counted, but they are much finer than in A. pusil/la. The detached segments are
not yet known; but, as seen in fig. 98, the segments appear to be very narrow, and
linear in form, the dorsal margin being hardly convex. The inner curve-lines and
nodules are obscure. These characters, as well as the finer striations, the finer
granulation of the bars in fig. 100 6, and the peculiar form of the middle space
in fig. 100, sufficiently distinguish it from A. pusilla, the only form it resembles.

This species occurs in the same Loch Fine dredging with those which imme-
diately precede.

The numerous examples here given of complex Amphore, to which, as we
have seen, two have been added from the simple group, prove that this group of
forms is by no means a small one, since so many have been obtained in one lo-
cality. It is worthy of remark, that the same dredging, which has yielded
at least 12 or 13 of the forms just described, also contains A. costata, Sm.,
already alluded to as the first Complex Amphora ever figured in this country,
though the peculiarities of its structure had not been fully appreciated. In fact,
as we have seen A. Grevilliana, A. complexa and A. fascata to form a smaller group
of closely allied species, so A. granulata, A. proboscidea, and A. cymbifera also
form another such group, to which A. costata also belongs. It would almost seem
as if the locality were favourable to these complex forms; for on the waters of the
Clyde the whole of them occur. We have also in these waters four Amphiprore,
with the remarkable additions of plates lying on the valves, namely, Apr. pusilla,
Apr. lepidoptere, Apr. plicata, and Apr. maxima; and lastly we have the doubtfully
named Apr. complexa, which exhibits the same complex structure in its middle
portion as we find in so many species of Amphora, that, namely, of segments
packed together, and converging on the ends, like those of an orange or melon.
But we must also remember that the same locality is equally rich in new forms
of simple Amphore.

GROUP VII.

MISCELLANEOUS.
In this last group I shall describe a few forms of genera not yet named in this
communication, and among them one or two whose real nature is doubtful.
These are :—

101. Navicula (?) Libellus, n. sp. | 106. Sceptroneis Caduceus, Ehr.
102, Nitzschia (?) panduriformis, n. sp. 107. Synedra undulata, Greg.

103. Nitzschia distans, n. sp., G. Toxarium undulatum, Bail.
104. 450 hyalina, n. sp, 108. Synedra Hennedyana, n. sp. (?)

105. Pleurosigma (?) reversum, n. sp.

and, as an Appendix,
109. Creswellia Turris, n. sp., (Arnott).

NEW FORMS OF MARINE DIATOMACEZ. 529

101. Navicula (2) Libellus, n. sp. Pl. XIV., figs. 101, and 101 6. Form of F.V.
rectangular, broad, with the angles rounded. The middle part is marked by lon-
gitudinal lines or folds, like the leaves of a book ; and when the two halves of the
F.V. separate, each retains a broad band of this lineate part. The breadth of
the detached halves on the F.V. is so great, that, when united, they must, it
would seem, mutually overlap, otherwise the resulting frustule would be much
broader than it is. S.V. rhombic or elliptic-lanceolate, broad, with obtuse ends.
Length from 0-003’ to 0:0035"; breadth of F.V. 0:0017’ to 0-002". The S.V. is
marked by very fine transverse strize; striae about 60 in 0-001"; median line
distinct ; nodule definite. When the edge of the 8.V. is seen, as in fig. 101 8,
the valve seems to be a compound one, formed of five or six, closely packed one
over the other. I cannot ascertain if this be so or not.

This species is frequent in Lamlash Bay, and it much resembles the form
figured by me in my second plate from the Glenshira Sand, under the name of
N. rhombica, of which also I had figured two of the S.V. in my first plate (Zrans.
Mic. Soc., vol. iv., pl. v., fig. 1, and Mic. Jour., vol. iii., pl. iv., fig. 16). But I
observe several uniform points of difference. NV. Lzbellus is more obtuse and broader, .
and its striation is not only much finer, but the strize are everywhere of uniform
size and at a uniform distance; whereas in JV. rhombica, they are near the middle
of the valve, not only stronger, but so much more distant than in the rest of the
valve as to be almost conspicuous. J. Lzbellus is also, on the whole, a larger
form than N. rhombica.

But it is very doubtful whether either of them be really a Navicula. They
have some resemblance, especially on the F.V., to Schizonema G'revillii, Sm.,
which, however, is a much smaller form. Still they may possibly belong to
Schizonema, but this cannot be ascertained except in living, or at least quite
recent and uninjured specimens. The F.V., with its foliated or complex struc-
ture, appears to me, however, to differ from that of a Schizonema.

I may here add, that there occurs in Lamlash Bay a much smaller form of
the same shape, but not foliated, at least not distinctly so. This is perhaps the
true S. Grevillit.

102. Nitzschia (?) panduriformis, n. sp. Pl. XIV., fig. 102. Form linear,
broad, incurved in the middle, acuminate at the ends, which are usually obtuse
and rounded, but sometimes acute and sub-apiculate. Length about 0-003’ ;
breadth in the middle 0-001’; at the shoulders 0:0012". The specimen here
figured is longer than usual, and the only one I have seen of this length. Margin
punctate. There is a faint indication of a double keel in the middle of the valve.
Striation fine, both transverse and oblique; strize about 48 in 0-001".

This species occurs in several of the Loch Fine dredgings, and is not rare.
The striation is similar to that of Zryblionella constricta, Grig. (Mic. Jour., vol.
iii., pl. iv., fig. 13); but the present form is much larger, and is distinguished

VOL. XXI. PART IV. 7c

530 PROFESSOR GREGORY ON

by the marginal puncta. Still it resembles a Tryblionella about as much as it
does a Nitzschia, and I therefore give it with a query as to the genus.

103. Nitzschia distans, n. sp. Pl. XIV., figs. 103 and 1036. Form of F.V.
nearly rectangular ; margin punctate, the puncta being very distant, some in
pairs, others single, 5 or 6 in 0-001". The punctate margin bends slightly in-
wards to each end, so that the ends would be narrower than the middle but for
two small hyaline expansions at each end, which renders the extremities a very
little broader than the middle. Length about 0°:0058’; breadth about 0-001’.
S.V. linear-lanceolate or rhombic-linear, narrow, broadest in the middle, where
the breadth is 0°0005’ ; ends acute, keel central. The whole form is somewhat
hyaline.

This species is not rare in the Glenshira Sand, and I was only prevented from
figuring it in my last paper on that deposit by want of room for the figure. Since
then I have found it frequent both in Lamlash Bay and in the remarkable stony
dredging from Loch Fine, so often mentioned, from which the present figure is
taken. It is probably striated, but I have not been able to resolve the striation.

I may here state that the form, of which a drawing was made, but not in-
serted in the plate just alluded to, seems to differ in some points from this, which
is the more frequent. In that form, the puncta, though distant, were regular,
and, as stated in the description, which was printed without the figure, appeared
to be constricted, and to have fine lines proceeding from one constricted punctum
to the constriction in the next. As the F.V. of this form had not the terminal
expansions, a circumstance which at the time I attributed to accident, I am in-
clined to believe that that figure really represented a different species. This I
have not had time to ascertain. But the present figure represents accurately the
form which from the first | had named Néz. distans.

104. Nitzschia hyalina, n. sp. Pl. XIV., figs. 104 and 1046. Form of F.V.
rectangular, with expansions at the extremities. On each margin is a row of
small puncta. Length 0°0034’; breadth 0-0004". S.V. linear, narow, and towards
both ends contracted to long and still narrower terminations. Keel apparently
double ; but perhaps one is seen through the very hyaline valve. The whole form
is so hyaline as to be easily overlooked.

This delicate species is tolerably frequent in the Loch Fine dredging so often
mentioned. It is possible that it may be a Homeocladia, but I have no means at
present of deciding this point. It is certainly not one of the species of H. figured
in the Synopsis.

105. Pleurosigma (?) reversum, nu. sp. Pl. XIV., figs. 105 and 105 6. Form
linear-lanceolate, narrow, somewhat contracted on each side of the middle por-
tion, and again expanding towards the ends, which are elongated, and have the
expansion all on one side, but on opposite sides at the two apices. On the non-
expanded side of the elongated ends, the margin is nearly straight, or slightly in-

|
.

——

NEW FORMS OF MARINE DIATOMACEA. 531

curved. The whole form has a strange appearance, as if we were to take two
long, narrow stockings, cut them across at the widest part, and join them at the
cut ends, with the feet pointing opposite ways. From this last character I have
named it. Length 0-005’ to 0-006"; greatest breadth 0°0006." Median line sig-
moid, straight in the middle, and suddenly bent near the ends in opposite direc-
tions. Striation so fine that I have not yet succeeded in resolving it, and therefore
not easily visible under a power of 400 diameters.

This singular form occurs in the stony Loch Fine gathering so often referred
to. I have as yet only seen the two specimens here figured, and two more; but I
have not searched for it, these being so remarkable, and so like each other, as to
indicate sufficiently, in a general way, the existence of the species. I do not feel
quite certain as to its genus; but I think it right to direct the attention of ob-
servers to it. It will probably be found more abundantly in some dredging or
gathering from a different locality in the Clyde.

106. Sceptroners Caduceus, Ehr. Pl. XIV., fig. 106. I cannot enter into a
detailed description of this species, as the fragment here figured is the only spe-
eimen of it I have yet seen in these dredgings, or in any British gathering. And
I figure it chiefly as evidence that this genus, which is frequent in several Ameri- —
can fossil deposits, yet lives in our waters, although we have yet to find it in such
abundance as will probably occur near its true habitat. Earensere thus describes
the genus (Bericht der Berlener Akademie, 1844, p. 264), “ Animal e Bacillariis
Echmelleis, affixum? Lorica simplex equaliter bivalvis silicea stiliformis com-
pressa, nonconcatenale, cuneata (viva facile pedicellata). Sutura laterum utrus-
que valvze longitudinalis media, umbilicus nullus. Habitus AZeridi non concate-
nati aut Gomphonematis, umbilico laterali carentis.”

The species, S. Caduceus, is distinguished by its long slender form, having
a central expansion, and another at one end, while the other end is long and
narrow, and by its very coarse moniliform striz. In this fragment we have the
large end, which is unusually large, for it is commonly of a narruwer and some-
what elliptical shape.

This form, which adds one to the list of British genera, occurs in the same
Loch Fine dredging as the preceding one, and so many more.

107. Synedra undulata, Greg. Toxariwm undulatum, Bail. Pl. XIV., figs. 107
and 107 6. Form of frustule very long, and very slender. F.V. rectangular, very
narrow ; 8.V. with an elongated central expansion, and two small semi-elliptic
terminal ones. Margin undulated. Strize conspicuous, moniliform, in the expan-
sions passing, towards the middle, into an indiscriminate punctation. Length
0-023"; greatest breadth of 8.V. 0:00035" ; breadth of the longer and narrower por-
tions hardly 0:0001.’ So that the length of the frustule is about 70 times the
width of the broadest part of the S.V., and more than 200 times that of the greater
part of the valve.

532 PROFESSOR GREGORY ON

Professor SmrrH describes the S.V. as arcuate, as in fig. 107 6; but I find it very
often quite straight, as in fig. 107. The arcuation seems to be accidental, due only
to the great slenderness of the frustule, and therefore common; but it is most
probably naturally straight in the S8.V. as well as on the F.V. Professor BarLey
represents it as straight, although he figures a specimen of the enormous length
of 0:0265." Those which are not straight are bent quite unequally, some very
little, others considerably, others only at one end, and others more at one end
than the other. I feel pretty sure, therefore, especially as straight examples are
frequent, that it is not essentially an arcuate form.

This very remarkable species, the longest known Diatom, except a Chetoceros,
figured along with it by Baitry, which is as long, was first observed in this
country, by me, in the Glenshira Sand, in which, however, I could not find, among
some hundred specimens, one entire frustule. I figured three fragments, two of
them nearly complete, in my first paper on the Sand (Mic. Jour., vol. iii., pl. iv.,
fig. 23), and was able to calculate, that if entire, its length would be about one-
fiftieth or one fortieth of an inch, or 0-02" to 0:025". The length of the specimen
here figured lies between these measurements, that of Professor BAILEY’s figure is
a little above the highest of them. After my paper with the incomplete figures was
published, I became acquainted with the earlier observations of Professor BarLey,
who had found it living on Sargassum on the American coast. I found one specimen
of it also recent, but still fractured, before my paper was printed, in a gathering
made by Professor SmitH on the south coast. Subsequently, Professor Smrru
found it frequent in Cork harbour, though smaller than in America. Last year
(1856) I found it frequent in Professor ALLMAN’s Lamlash Bay dredging, and spa-
ringly in the other dredgings. As no entire figure of it has yet appeared in this
country, I have here given two figures, one arcuate, the other straight.

108. Synedra Hennedyana, n. sp (?) Pl. XIV., fig. 108. This form is in all re-
spects similar to the preceding, except that the margin is not undulated. Fig.
108 represents it of the same length as S. wndulata.

I first noticed this form along with S. wndulata, in July 1856, in Professor
AuLMAN’s Lamlash Bay dredging, but I considered it as simply a variety of that
species. I was led to do so by observing that in S. wndulata it often happens
that a considerable portion of the margin is devoid of undulations. But several
other observers who had seen it, adopted the opinion that it was distinct from
S. undulata. Mr Roper was, I believe, one of these; and I rather think Professor
WaLker-ARNOTT, and Mr HENNEDY have come tothe same conclusion. Professor
ARNorTT informs me that it occurs in a gathering from the Clyde, I believe near
Cumbrae, without a single frustule of S. wndulata. As this gathering was made
by Mr Hennepy, if lam not mistaken, and as he has at all events studied the
form in question, I have figured it under his name, with a mark of doubt, as I
am not yet quite satisfied that it is really a distinct species. In my material it

NEW FORMS OF MARINE DIATOMACE. 533

is mixed with S. undulata; and I know of no distinction beyond that of the ab-
sence of undulations on the margin, unless it be that the strize in S. Hennedyana
are perhaps a little finer than in S. wndulata. Even of this I am not sure.
But the figures, which are very accurate, will enable the reader to form his own
conclusions.

Such are the results obtained, up to this time, by the examination of these
11 gatherings from the Firth of Clyde and Loch Fine, 10 of which are true dredg-
ings, while the 11th is derived from Corallina officinalis, to which a good many
Diatoms have adhered.

From the remarkable analogy between the Glenshira Sand and these gather-
ings, we may regard it simply as another dredging, the marine forms in which
have been derived from Loch Fine. I have shown that the period at which it
was deposited has not caused any material difference of composition, and that we
may say, in general, that it does not differ more from the recent dredgings than
they do from each other.

Considering, then, all as supplying us with existing forms, we are struck with
the unexpectedly large number of undescribed species which this exploration of
the waters of the Clyde, though very limited in the area whence the materials
were derived, has yielded in a short space of time.

It is worthy of notice, that the great majority of these new forms are not
only new as British species, but have not been observed elsewhere, although
EHRENBERG and Baruey have both described many rich marine gatherings from
different parts of the world.

This proves that the existing stores of marine Diatoms have not yet been by
any means fully explored. It is therefore highly desirable that dredgings or
soundings from all seas and estuaries, and from every part of them, should be
procured and carefully searched. From what has been already recorded, as well
as from the results here given, it appears that estuaries and harbours, or other
localities near the coast, are likely to be the richest in Diatoms, perhaps from the
comparative shallowness of the water. But the conditions of the distribution
of these organisms in the sea, and of the accumulation of their indestructible si-
-liceous shells, are not yet known with certainty. Thus, while every one of these
Clyde dredgings proved more or less rich in Diatoms, I have found several from
the Long Narrows, in the Firth of Forth, kindly given me by Dr Hecror, to be
very poor in comparison, and indeed not worth the trouble of mounting. And
while Barney has found many interesting forms of this class in soundings from a
depth of 1700 fathoms, and even of 2700 fathoms, in the Kamtschatka Sea, a num-
ber of Atlantic soundings, from depths varying from 85 to 2000 fathoms, which,
by the kindness of Professors W. Tuomson and ALLEN THomson, I was allowed to
see, contain indeed Foraminifera and Polycystineze, but are almost entirely desti-
tute of Diatomaceze. Yet Baiztey has found Diatoms in Atlantic soundings from

VOL. XXI. PART IV. 7D

534 PROFESSOR GREGORY ON

other localities. We have nothing for it, therefore, but to examine every speci-
men of sea-bottom that we can procure. And the example of the Firth of Clyde
is sufficient to prove that much remains to be done.

It should also be stated here, that these Clyde dredgings are not exhausted.
Indeed, it is a work both of much time and much labour fully to exhaust any
such mixtures as these are.

While these sheets are passing through the press, I am in a position to state,
that I have already collected, from the same materials, so considerable a number
of additional undescribed forms, that it will be necessary to describe and figure
them in a supplementary memoir. Of these forms, a large proportion are discs,
many of which are small, or only of a medium size; but there are also Naviculoid
forms, Amphoree, and forms of a few other genera.

I would further direct attention to the fact, that these dredgings differ ma-
terially from each other, each being characterized by the prevalence of certain
forms, although some forms are common to all. Thus, off Inveraray and Stra-
chur, in Loch Fine, the proportion of large Campylodisci was very much greater
in two gatherings than in all the rest, whether there or off Arran; while in
Lamlash Bay, the material was remarkable for the great number and variety of
Amphoree, a character found in one only out of the seven dredgings from Loch
Fine. This shows that the deposits may vary much in regard to species, and
even genera, in localities at no great distance from each other, and points out the
advisability of searching every corner.

Lastly, it appears probable that some genera, whether such as have been
adopted by EnrenserG, Kurzine, BarLey, and others, or entirely new, will have
to be added to Professor Smiru’s list of British genera. This is especially the
case with the numerous new filamentous forms, hardly any of which agree with the
genera in the Synopsis. I have not for the present ventured to introduce any
entirely new genus, but I have added Pyaidicula and Sceptroneis of EHRENBERG,
and, more doubtfully, Dzadesmis, also admitted, in a recent paper, by Professor
Smira. I refrain from doing more; because I believe that genera established in
the present imperfect state of our knowledge of species as well as of genera, are not
likely to be permanent. In one case, I have pointed out the possibility of uniting
in one genus and in one species three forms, Campylodiscus simulans, Surirella
fastuosa, and Surirella lata, at present referred to two genera and three species.

In distinguishing and describing the very numerous new forms figured in this
communication, I have been careful to avoid unnecessary multiplication of
species. In numerous cases I have united forms apparently distinct which a
closer examination showed not to be so. And in every case where I have ad-
mitted a new species, it has been because I could not reconcile it with any figures
or descriptions which were accessible to me. I have also had the great advan-
tage of frequent consultation with Dr GREVILLE, whose opinion has deservedly

‘

q
ry
i
a

NEW FORMS OF MARINE DIATOMACEA. 535

very great weight with all students of the Diatomaceze. I have further to thank
Mr Roper for many useful hints, and for the use of some very accurate drawings
of forms observed by him, in many cases identical with those I had myself de-
scribed. .

It is impossible to do full justice to the scrupulous accuracy and to the ar-
tistic beauty of the figures which Dr GreviLLE has made of the forms which I
have described, and to the signal success with which Mr Turren West has en-
graved them. I can only say that I have seen no figures of this kind equal to
them in these respects, and that the chief value of communications like the pre-
sent is derived from the presence of good figures. Without figures, descriptions
are apt to be misunderstood, and inferior figures tend, more than any other
cause, to lead observers to multiply species unnecessarily. Those who are in
the habit of studying the Diatomaceze will agree with me, that a large proportion
of the figures in some works on the subject are worse than useless, and lead to
hopeless confusion.

There is another point on which good figures throw much needful light. In
many species, though by no means in all, the shape, as well as the size of the
forms, and even the striation, all vary to a great extent. In such cases, it is ~
most important that every author should figure a sufficient number of selected
forms, to show the real extent of the species. These variable species ought to be
thus treated individually, by which means many existing species would be got
rid of and reduced to a smaller number. I have attempted something of the
kind in Navicula varians (Trans. Mic. Soc., vol. iii., p. 10), and in this paper I
have done so partially in Navicula Lyra, Nav. Smithii, Amphora Proteus, and
Amphora levis. Such forms as N. elliptica, N. didyma (which I have in part illus-
trated in my last paper on the Glenshira Sand), V. Crabro and P. Pandura, for
example, and even V. Smithi, besides others in different genera, require much
fuller illustration than they have yet received.

Finally, I wish it to be understood, that in describing so many new species, I
make no pretensions to deciding authoritatively on disputed or doubtful points.
My sole object is to bring under the notice of observers, the forms which I meet
with. To do this, I must needs give them names, and in this respect I endeavour
to be as accurate as I can. I observe that Professor Smiru, in his last paper in
the Annals, objects to the establishment of new species, unless the specimens are
frequent. But although I have given, as distinct species, some forms which are
rare, | have not done so till after I had examined and compared many specimens of
each, except in one or two cases, such as Coscinodiscus umbonatus, where the form
is so striking and well-marked that even one specimen suffices.

If we confine our attention to one or two slides, then, indeed, rare forms can
not be sufficiently studied. But in the researches made in connection with this
paper, I have explored at least 1000 slides, most of them twice, many three times,

536 PROFESSOR GREGORY ON

and even oftener. Thus it happens, that I have compared as many specimens of
by far the greater number of the forms here mentioned as rare, as if they had
been very frequent, and I had only seen one or two slides.

Compared with many forms, all the Complex Amphoree would be considered
rare, but of these, I have in every instance examined numerous specimens, and
have satisfied myself of the constancy of their characters, which is the most im-
portant point.

I trust, therefore, that Naturalists will accept this paper as a simple contri-
bution to our knowledge of Diatomaceous Forms. As such I present it, leaving
to those who are better qualified for the task than I am, to decide on the con-
flicting claims of genera and species.

APPENDIX.

For the following description and figure of a very beautiful new form, belong-
ing to a new genus, [am indebted to my friend Dr Grevitte. The form in
question has not occurred to me as yet, but as Professor WaLKER-ARNOTT has
found it in the Clyde, it has a claim to be inserted in this account of new Clyde
forms.

Notice of a New Genus of Diatomacee. By R. K. Grevitxe, LL.D., F.R.S.E., &c.

My friend Professor Grecory having permitted me to introduce in this place
the description of a new and most interesting diatomaceous form, I gladly avail
myself of the privilege. Having been recently discovered in the Clyde, it may,
indeed, be considered as possessing some claim to appear in company with the
multitude of fine species described by Professor Grecory in the preceding pages.
This remarkable Diatom was communicated to me a few weeks ago, by my friend
Professor WALKER-ARNOTT, for publication and illustration. It is to be regretted
that he did not undertake this office himself; he has, however, very kindly sup-
plied me with notes of his views regarding it, so that he has rendered my labour
comparatively light. Professor WaLKER-ARNorTt’s attention was first directed to
the form in question by the Rev. R. CrEswE.x, who obtained it at Teignmouth,
from the stomach of Cynthia rustica (Phallusia rustica, Flem.), along with Bid-
dulphia Baileyi and other good things. It is, however, so scarce, that at present
it must be reckoned among the rarissima of its tribe. Very fortunately the speci-

mens which have been obtained are in a state to admit of satisfactory description. ©

Like Biddulphia and Isthmia, it forms chains, the links or frustules of which are
oblong, somewhat depressed at the ends, highly cellulate, separating transversely

NEW FORMS OF MARINE DIATOMACEZ. 537

into two equal valves. ‘The frustules are united by means of a circle of numer-
ous short, terminal processes of equal length, which ultimately separate in the
middle; and the detached frustules then appear furnished at each end with a
beautiful coronet, or circle of miniature turrets. This mode of connection is peculiar,
although perhaps analogous to that in Brddulphia. In the subject of these
remarks, however, the connecting processes do not appear to be so distinctly a
continuation of the substance and structure of the body of the frustule, as are the
horns of that genus, and must rather be regarded in the light of appendages.

With regard to the affinities of this beautiful little object, we may certainly
assume, that if a solitary frustule had alone been formed it would have been
referred by Kirzine at once to the genus Pyxidicula. But little or nothing is
known of the real nature of the variety of forms brought together under that
name. EHRENBERG’s own character for the original genus is as follows :—

** Animal e familia Bacillariorum, liberum, lorica simplici, bivalvi (silicea) ;
solitarium, globosum (=Gallionella divisione spontanea perfecta aut nulla). Die
Infusionsthierchen, p. 165.

But EurensereG subsequently constituted other genera or subgenera to receive
the accumulating species; and as the work in which they appear is not generally
accessible, I do not hesitate to give the characters verbatim in this place.

« Dictyopyxis, nov. gen. Pyw«idicule generis ea bivalyes subglobose aut tur-
gidz forme, quee valvularum teste strictura simpliciter cellulosa insignis sunt ab
lis, quze continua et simplici membrana silicea includuntur, aut appendicibus
variis instructze sunt, gravius differunt et facillime distinguuntur. Cellulosas
igitur in Dictyopyxidis subgenere colligendas senserim. P. cruciata, Cylindrus,
hellenica et Lens huic subgeneri nunc inscribende sunt.”—Hhrenb. Bericht. der
Berl. Akad., 1844. P. 262.

“« Stephanopyats, nov. subgenus. Pyaidicule generis bivalves turgid aut
subglobosze formze, que valvularum testze structura cellulosa insignes sunt et
denticulorum, aculeorum aut membrane coronam in media quavis valvula gerunt
in hoc Pyxidicule subgenere colliguntur.”—Ehrenb., l. c., 1844. P. 264.

« Xanthopyxis, nov. subgen. Pyxidicule subgenus bivalve turgidum sub-
globosum. Valvularum teste silicee continue integerrimee nec cellulose, super-
ficie hispida, setosa aut alata.”—Hhrenb., /.c., 1844. P. 264.

Kurzine, in his Species Algarum (1849), reunites the whole, giving twenty-
two species, all of which, except two, are fossil. The frustules, according to him,
are “non concatenata.” Mr CresweEL.’s Diatom is, therefore, by a most import-
ant character, excluded. Taking a simple frustule, and leaving the processes out
of view, it much resembles Dictyopywis hellenica (Ehrenb. Microgeologie, tab. xx.,
fig. 32), and also Stephanopyxis appendiculata of the same work, tab. xviiL., fig. 4 ;
but that species has only a single tooth at each end, and is provided with a sort
of narrow zone or annulus. — It resembles still more closely Stephanopyxis apicu-

VOL. XXI. PART IV. 7E

538 PROFESSOR GREGORY ON

lata (Ehrenbd., l. ¢., tab. xix., fig. 13) which is represented with three terminal
teeth ; but these teeth can scarcely be the remains of a corona, as Kijrzrne, in de-
fining the frustule, says, “utroque fine medio apiculis elongatis hispido.” Upon
the whole, the safe course seems to be to regard the subject of this notice as not
only specifically but generally new; and I gladly adopt the suggestion of Pro-
fessor WALKER-ARNOTT, that it receive the name of Creswellia in honour of its dis-
coverer, the Rev. R. CrESWELL, a gentleman well known to Algzologists, and to
whom Professor Harvey has already dedicated a new British Schizothrise. The
following character will distinguish it at once from all its allies.

Creswellia. Frustules cylindrical, two-valved, cohering by short, filiform pro-
cesses into a continuous filament. Valves cup-like, cellulate, destitute of any si-
liceous connecting band. Pl. XIV., fig. 109.

This singularly interesting Diatom, which may be called Creswellia Turris,
has only been found in the locality already mentioned by Mr CresweE tt, and off
the Island of Cumbree, where it was dredged along with the nests of Lima hians
by Mr Hennepy, and a single frustule detected by Dr WaLKER-ARNnorTrT.

The figure represents four frustules, the largest number which has been
hitherto observed in connection. It will be perceived that in two of the frustules
one of the valves is dark, and more or less opaque. This appearance we are quite
unable to account for. It sometimes happens that the whole frustule is dark.
Generally they are all beautifully clear. The structure is highly cellulate, the cells
hexagonal. The length of the frustule is about -0028’; the breadth about -0016’.

EXPLANATION OF PLATE IX.

Fig. 1. Nayicula minor, n. sp. Fig. 16. Navicula Smithii, var. y, nitescens.
— 2. Cluthensis, n. sp. — 1%. 5 Smithii, var. 6, suborbicularis.
— 3. inconspicua, n. sp. — 18&18b, maxima, Greg., S.V. and F.V.
a brevis, n. sp. — 19. Pinnularia subtilis, n. sp.
— 5 Claviculus, n. sp, S.V. x 800.; — 20. rostellata, n. sp.
DIO MOs eer. Ve X LOU OS oes UO.) — ee Allmaniana, n. sp.
S.V. x 400. — 22, Pandura, Bréb., var. 8. elongata.
— 6. Musca, n. sp. — 23. Cocconeis distans, Greg.
— 7. rectangulata, n. sp. 24. ornata, n. sp.
8. nebulosa, n. sp. — 25. dirupta, n. sp.
att a Oe oe ace Barclayana, n. sp. — 26. nitida, n. sp.
— 10. spectabilis, n. sp. — 2%. . pseudomarginata, n. sp.
— il. praetexta, Ehr. — 28. major, n. sp.
12, +. Bombus, Ehr. =— §29,°-).2: splendida, n. sp.
— 138136, Lyra, Ehr. All the above, except figs. 5 and 5 b, are magnified
— 14&146, Lyra, var. B. 400 diameters.
— 15. Smithii, var. 8, fusca.

EXPLANATION OF PLATE X.

Fig. 30. Denticula (?) interrupta, n. sp.

— 3i. (?) capitata, n. sp.
— 32. (?) ornata, n. sp.
— 33,330, & L

ay i ...(2) leevis.

Fig. 34. Denticula nana, n. sp., F.V. 346; do. S.V.
ree ist minor, n. sp. F.V. 35d; do. S.V.”
distans, n.sp., F.V. 366; do. 8.V..

OG eae
37 & 37 6,...staurophora, n,sp.,F.V.37¢; do.S.V

Fig.

NEW FORMS OF MARINE DIATOMACEX.

; marina, n. sp., 39 b; do. S.V.

. Diadesmis (2?) Williamsoni, F. Vs 406; do.
S.V.

. Meridion (?) marinum, n. sp.,F.V., 416; do.
S.V

. Pyxidicula druciatas Ehr.
. Orthosira angulata, n.sp., F.V., 436; do. F.V.

EXPLANATION

. Coscinodiscus centralis, Ehr.

. Eupodiscus subtilis, n. sp., Ralfs.
. Campylodiscus centralis, n. sp.
Ralfsii (?) Sm.

EXPLANATION

56. Amphiprora pusilla, n. sp., F.V., 360; do.
stale

57. plicata, n. sp., F.V.

58. elegans, Sm.S.V., 58 b; do. F.V.

59. lepidoptera, n. sp., F.V., 59 b;
do., S.V., 59 ¢; do. peculiar
view.

60. obtusa, n. sp., F.V.

61. maxima, Greg., F.V.,616; do.
S.V.

62 &626(?) complexa, n. sp., F.V. entire;
62¢;do. half frustule, 62 d
and 62 ¢€; do. detached seg-
ments.

63. Amphora turgida, n. sp.

. Denticula fulva, n. sp., F.V. 38 6; do. 8.V. |Fig.

539

44, Melosira (?) or Coscinodiscus (?) qu. (2) sp. (?)
0. sp.

45. Coscinodiscus nitidus, n. sp.

46. punctulatus. n. sp.

47. concavus, Ebr.

48. 6 umbonatus, n. sp.

All the above are magnified 400 diameters.

OF PLATE XI.

Fig. 53. Campylodiscus angularis, n. sp.

— 54& 546,... eximius, 0. sp.

55. a limbatus, Bréb.

All the above are magnified 400 diameters.

OF PLATE XII.

Fig. 64. eee nana, 0. sp.

— 65. macilenta, n. sp.

— 66. angusta, 0. sp.

— 67. binodis, n. sp.

— 68&68b, ventricosa, n. sp.

— 69. monilifera, n. sp.

— 70. lineata, n. sp.

— 71. Ergadensis, n. sp,

— 72. levissima, n. sp.

— 73. pellucida, n. sp., 736; half frus-

tule of do.

— 74,746, & ai n. sp., 74 ad ; Amphora, qu. ?

74¢, a form of A. levis ?

All the above are magnified 400 diameters.

EXPLANATION OF PLATE XIII.

93 6b; do. pack of similar seg-
ments.

crassa, n. sp, 94 b, 94 c, and 94d;
do. detached segments.

pusilla, n. sp., simple and complex
views.

Oe Taco

958958, {

. 75. Amphora exigua, n. sp. Fig. 82. sen kners lyrata, n. sp.
ao. .. dubia, n. sp. — 83. Milesiana, n. sp.
GT. truncata, n. sp. — 84, elongata, n. sp.
78 &7 8 b, oblonga, n. sp. — 8b. quadrata, n. sp.
79. ... robusta, n. sp.. 79 b and 79 c; half|— 86. excisa, 1. sp.
frustules. — 87. nobilis.
80. spectabilis, n. sp.; 800; do. var. B,|— 88. Arcus, Greg.
80 ¢; do. var. y; 80d; do. view}— 89. Greyvilliana, Greg.
showing thecomplexstructureofthe |— 90. fasciata, n. sp.
species; 80¢; do.detachedsegment.|— 91. complexa, n. sp.
81,816, 81 All the above are magnified 400 diameters.
c, 81d, «| ... Proteus, 0. sp.
81 e,
EXPLANATION OF PLATE XIV,
93. Amphora acuta, n. sp., detached segment; Amphora granulata, n. sp., simple and

complex views of two

Fig. 96, 96 b, frustules ; 96 ik detached

96 ¢, &

96 d segpment; 96 ¢; form
é qu? allied to A granu-
lata ?

540 PROFESSOR GREGORY ON
Amphora cymbifera, n. sp., simple | Fig. ee i
Fig. 97&97 b, p y erie abe zfs 97 ¢: re 055,| Pleurosigma ? reversum, n. sp.
detached segment of do. | — 106. Sceptroneis Caduceus, Ehr.
proboscidea, n. sp., simple | — 107. Synedra undulata, Greg. (Toxarium undula-
— 98&98b and complex views, 98 c, tum, Bailey). Two specimens of the
4 and 98 d; detached seg- S.V., the one straight, the other arc-
mentsof do. uate.
— 99. Amphora costata, Sm., detached segment. —108. .... Hennedyana, n. sp., S.V.
—100& bacillaris, n. sp., simple and com-
TOONS) ime plex views.
— 101. Navicula (?) Libellus, n. sp., 1016; do, edge APPENDIX.
view.
— 102. Nitzschia (?) panduriformis, n. sp. — 109. Creswellia (nov. gen.) Turris, n. sp., Arnott.
= it By ney distans, n. sp., 103 b, do. S.V. All the above are magnified 400 diameters.
— 104. fe hyalina, n. sp., 104 b, do. 8.V.
Postscript.

While the preceding pages were passing through the press, I have been able
to examine with care numerous specimens of most of the forms there described,
and I wish here to modify to a small extent some of the views I have expressed.
In every instance, I speak after the comparison of a very large number of fine |
examples.

1. Navicula nebulosa, fig. 8. I wish to observe, that after a very careful com-
parison of this form with V. Hennedyi, I have no longer any doubts as to its
being a distinct species. I find it remarkably uniform in its characters, and par-
ticularly in its oval form, with the ends on the whole broadly rounded, while it
has a slight angularity in the middle, and a slight trace of acumination at the
apices. It is equally uniform in the narrowness of the marginal band of strie,
in the fineness of the striation, and in its very peculiar colour and nebulous
aspect. In all these points, V. Hennedyi differs from it, as I have stated. But
while these points of difference appear trifling, and are difficult to express in
words, I must observe, that there is no real resemblance between the forms, and
that when, as often happens, both being frequent, they occur close together, and
of equal size (though NV. Hennedy? is usually a larger form), it is quite impossible,
even under a low power, to confound them together, the whole aspect of the two
forms being remarkably different.

2. Navicula spectabilis, fig. 10. Having found, in certain densities, many very
fine specimens of this form, I have to state, that it occurs of nearly twice the
size of the individual figured, and that it is perfectly uniform in its characters.

3. Navicula Bombus, Ehr., fig. 12. This form also has occurred abundantly in
certain densities, and Iam now quite satisfied that it is a distinct and well-marked —
species. In the description I have omitted to mention an important character,
namely, that it is never, literally,—not in one out of thousands of examples—sym-

NEW FORMS OF MARINE DIATOMACEA. 541

metrical. One-half is always more or less larger than the other, and the amount
of surface on each side of the median line is unequal. This does not occur in any
other panduriform Navicula, except only occasionally in NV. didyma, which can-
not be confounded with the present species. NV. splendida, N. incurvata, N.
Musca, and N. (or P.) Pandura, are all remarkable for symmetry. In addition
to this want of symmetry, which is invariable, it may be stated that, although
several Navicule, and even some of the panduriform group, vary a good deal in
shape, there is no species which is more uniform in this respect than NV. Bombus.

4. Navicula Smithit, var. 8, fusca, fig. 15. A careful study of very numerous
specimens, both of this form, and of that which I take to be the typical N.
Smithii, has now entirely satisfied me that N. fusca is truly a variety of WN.
Smithii. But it must be added, that this, like the fresh-water JN. elliptica, is one
of the most variable species, not only in form, but also in the striation, which
varies from what may be called fine to exceedingly coarse; in colour, which
varies from colourless to dark brown; and in general aspect,—WV. Smuthii being
usually destitute of the remarkable longitudinal ridge or shade on each side of
the median line, so conspicuous in WV. fusca. In all these points, a perfect grada-
tion may be traced without difficulty.

5. Navicula Smithit, var. y, nitescens, fig, 16. Having found this form abun-
dantly in one density, I have now come to the conclusion that it is no variety,
but a distinct species. I find it perfectly uniform in all its characters, and the
remarkable peculiarity of the median line, which is invariably a broadish white
line with perfectly parallel sides ; while that of NV. Smithii, including WV. fusca,
is always doubly conical, being much broader in the middle, and forming a very
acute point at each apex, seems effectually to separate it from that species. The
shining aspect of the strize is also peculiar.

6. Navicula Smithu, var. 6, suborbicularis, fig. 17. This form has also occur-
red abundantly, and I am now able to state that it is so uniform in its characters,
and so peculiar in its aspect, that it must be admitted as a distinct and well-
marked species. The only variation, except one to be presently mentioned, is in
size, as it now and then occurs of twice the length of the figure, or even more, in
which case it is more oval in shape, though always very broad. But the peculiar
structure about the median line, giving the appearance of two white, elliptical
bands meeting in the nodule, or of one long elliptical band, suddenly constricted
in the middle, seems to be quite invariable, and sufficient to distinguish it. The
fact, also, that the strize are hardly visible, except on a broad marginal band,
where they are very conspicuous, having the shining aspect of those in JV. nites-
cens, though coarser than in that species, as well as the permanence of its very
peculiar form, seem to indicate that it ought to be separated. Neither in this

VOL. XXI. PART IV. (F

542 PROF. GREGORY ON NEW FORMS OF MARINE DIATOMACEZ.

form nor in the preceding, have I seen the slightest trace of any tendency to pass
into N. Smithit, or into its variety NV. fusca.

I have, indeed, lately noticed one variety of the present form, namely, a pan-
duriform variety, agreeing with the type in size, in general aspect, and in the pe-
culiar median line. This I shall describe and figure on a future occasion.

I may here add, that I shall also have to describe and figure another new form
of Navicula, occurring abundantly with the preceding ones, which at first I was
disposed to refer, like them, to V. Simithit. But I find it so uniformly peculiar,
that I must separate it also.

7. Denticula (2) levis, fig. 33. I have some reason to think that I have detected
the S.V. of this species. The F.V. is frequent in some densities, but it would
appear that the entire frustule is so much broader on the F.V., that it never lies
on the S.V., and that the valves are never, or hardly ever, separated. Even when
separate, the S.V. must be so very narrow, and perhaps so convex, that this side
is not usuallyseen. In one case, however, where one of a group has been partly
turned, I think I can see that the S.V. resembles in shape that of D. fulva, only
smaller and narrower.

I have also to add to the list of British species two forms, both remarkable,
which occur in Lamlash Bay.

These are,—1. Cocconeis Morrisiana, Sm., a very curious species lately found
by Professor Sm1tu, I believe, in a gathering from the Levant or from the Black
Sea. 2. Pleurosigma compactum, Grev.; described and figured by Dr GREVILLE,
from Trinidad. I propose, in a future paper, to figure these two species as British
forms.

I have just now been able to add to the figures, one of the very remarkable
detached segment of Amphora spectabilis, as described in the text. It will be
found in Pl. XIIL, fig. 79 e.

28th May 1857.

(
(
’
q

541*

CORRIGENDA.

I have to request the reader’s attention to the following corrections, which I wish to
make in regard to some points in the preceding paper.

1. The form represented in fig. 52, Plate XI., as a modification of Campylodiscus Ralfsii,
Sm., is, as I am now convinced, entirely distinct from that species, which in fact, occurs in
some of the dredgings along with it; and, in addition to its being uniformly small, exhibits a
very different aspect. Fig. 52 agrees with the description given by Da Brusisson of his
C. decorus, and I have no doubt belongs to that species, which must therefore be added to
the list of British Diatoms.

2. Additional observations have satisfied me, that the form represented in fig. 95 e,
Plate XIV., is not a form of Amphora granulata, but an entirely distinct species, to be more
fully described at a future time.

3. I wish to mention, that although I cannot see any reason to separate the two forms,
represented in figs. 80 6, and 80 c, Plate XIII., from Amphora spectabilis, fig. 80, so far as the
simple view of the latter is concerned, I have not yet been able to trace the complex structure
of A. spectabilis, shown in fig. 80 d, in these smaller forms. Whether this is because I have
not yet employed the highest powers of the microscope for this purpose, since these small
forms have much finer markings than the larger one, or whether the complex structure
occurs in the larger alone, while the smaller remain always simple; or whether, finally, the
two smaller forms belong to a different species, are questions which I cannot yet answer.

4. Having, by the kindness of Dr A. S. DonkKIN, of Morpeth, been enabled to examine a
most interesting marine gathering made by him, in which several of the forms described in
this paper, as well as several of those yet to be described as occurring in the Clyde, are met
with, I have now to state, that I find Amphora Grevilliana in that gathering, with almost
exactly the form and aspect of Amphora complexa, fig. 90, Plate XIII., while detached seg-
ments also occur, evidently belonging to it, and having the straight dorsal margin, but yet in
all other points agreeing with those of A. Grevilliana, as shown in fig. 36*, of my third plate
of Glenshira forms, and as seen in the present paper in the entire 4. Grevilliana, fig. 89, Plate
XIII. Ihave therefore to withdraw A. complexa as a distinct species, and to request the
reader to consider the figure (fig. 90), as representing one view of a straight-sided form of
A. Grevilliana. In this variety, as seen in Dr DonKIN’s gathering, and as I have also
observed in the Glenshira Sand and in the Clyde, the detached segments are much narrower
than when the dorsum is convex. I have specimens of the convex segments, from the Clyde,
nearly three times as broad as Dr DoNKIN’s, with the straight dorsum. I would further
observe, that in all probability, fig. 89 represents a frustule, or possibly a half-frustule,
viewed from the flat or concave side, while the frustule in fig. 90 is seen from the convex
side, so that the flat-lying lateral segments are not so distinctly seen. I must remind the

VOL. XXI. PART IV. TOR

542* CORRIGENDA.

reader also, that the names and descriptions of figs. 90 and 91, A. Complexa, and A. fasciata,
have by some mistake been transposed, as stated in the errata, which I did not discover till
it was too late to correct it. Whether A. fasciata, fig. 91, shall also prove a form of A.
Grevilliana, for which I gave it in my last paper on the Glenshira Sand, I cannot at present
determine.

5. The form represented in fig. 74d, Plate XII., is, as I am now quite satisfied, entirely
distinct from Amphora levis, and must be hereafter described as a new species.

6. I have been able to introduce, at fig. 68c, Plate XII., a figure of the remarkable
detached valve of Amphora ventricosa, which resembles a very slender Cymbella, and
occurs even longer and narrower than in the figure. In one dredging, I find it tolerably
frequent.

7. In the dise of Coscinodiscus centralis, Ehr., as represented in fig. 49, Plate XI., the
central cells are shown considerably larger than is usually the case in the specimens which I
have of this Diatom. Indeed the cells, in the figure, are more like what is seen in the centre
of C. Asteromphalus, Ehr., and the question arises, whether the specimen figured may not be-
long to the last-named species, or whether these two species may not, in reality, be essentially
one andthe same. In a large number of specimens of C. centralis which I have lately
examined, the central cells are invariably but a little larger than the rest, so that the form
represented in fig. 49, if it be C. centralis, and I see no other difference, must have been, in
this respect, abnormal. I may add, that in these beautiful discs, some of which are consider-
ably larger than the one figured, the cells are distinctly arranged in spiral lines, as in engine-
turning, and as is seen also in C. radiatus. This character is but slightly indicated in the
figure.

W..G.

lst August 1857.

ERRATA.

. 510, line 3, for “vertical” read “ ventral”

. 514, line 13 from bottom, for “ Plate XIII. fig. 75” read “ Plate XII. fig. 75”

. 518, line 3 from bottom, for “80 e” read ‘81 e”

. 523. Transpose the paragraphs numbered 90 and 91, so that they shall be read thus :—
90. Amphora complexa, n. sp., &c. &c. And
91. Amphora fasciata, n. sp., &e. &e.
Also same page, line 2, for “to which I now proceed,” read ‘to be presently de-

ola la" jaa)

scribed.”
P. 531, line 22, for ‘“‘Echmelleis’’ read ‘‘ Echinelleis”
,, 28, for “ nonconcatenale” read “ nonconcatenata”
es », 23, for “utrusque” read “ utriusque”
P. 539. In the Explanation of Plate XII., after —74, insert ‘‘—75...exigua, n. sp.”
In the Explanation of Plate XIII., expunge the first item.
Also, transpose the words opposite to — 90 and — 91, so that they shall be as

”

follows :
— 90. ... complexa, n. sp.
— 91. ... fasciata, n. sp.

And after — 91 insert
— 92. ... sulcata, Bréb.
— 93. ... acuta, n. sp. Pack of united segments.
In the Explanation of Plate XIV., for “Fig. 93” read “ Fig. 93” 6, and expunge the words
of the second and third lines.
The reader is requested to make, in the Explanations, as repeated opposite Plates XIL.,
XIII, and XIV., the corrections above indicated as required on page 539.

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EXPLANATION OF PLATE IX

Fig. 1. Navicula minor, n. sp.

= 2.
ee

em 4:
5

= é.

— 7.

Ee) 58:

=e 9,
10:

22 UTy.

== ON non
= 13.8138,
— 14814},
Pueuise® US,

Cluthensis, n. sp.
inconspicua, n. sp.
brevis, n. sp.

Claviculus, n. sp., S.V. x 800.
5b, do., F.V. x 800. 5c, do.

S.V. x 400.
Musca, n. sp.
rectangulata, n. sp.
nebulosa, n. sp.
Barclayana, n. sp.
spectabilis, n. sp.
praetexta, Ehr.
Bombus, Ehr.
Lyra, Ebr,

Lyra, var. B.
Smithii, var. 0, fusca.

. 16. Navicula

— 29

All the above, e

Smithii, var, y, nitescens.

mele Smithii, var. 6, suborbicularis.
— 18&18b, maxima, Greg., S.V. and F.V.
— 19. Pinnularia subtilis, n. sp.
— 20. rostellata, n. sp.
— 21 Allmaniana, n. sp.
— 22. Pandura, Bréb., var. 8. elongata.
— 23. Cocconeis distans, Greg.
— 24. ornata, n. sp.
— 20. dirupta, n. sp.
— 26. nitida, n. sp.
— 27. . pseudomarginata, n. sp.
— 28. major, n. sp.

splendida, n. sp.
xcept figs. 5 and 5 b, are magnified

400 diameters.

oe

¥ de =
: Ri yey ery rE i
: ideas A ser ail to hnat tt..—
Na ' jovel btatelh clei)
ee OA were ., 2
: eee a |
: a ee ap wh itier ~
‘er i A ipeperebirsey re
: Wi, i #z
saa pm. es

feRicwpa wee A sa é eA bite drrodn oft ITA
wT ve et OUP

iat / ae \Sigakintt adobe. BT ght

pw aheidood un ; seme ry T=
i ‘ a ees Bi met
inf af il

mn AH mo AN ad
7 1 oh

bg , a

=
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2
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~

Trans Roy Soc Edin Hi X Vol XXL

3
3
2
&
é
a
$
3
3
fea) .

EXPLANATION OF PLATE X.

. 30. Denticula (?) interrupta, n. sp.

31. (?) capitata, n. sp.
32. (?) ornata, n. sp.
33, 33 b, &

33 ; } ...(?) levis.

34. nana, n. sp., F.V. 346; do. S.V.

eae © } minor, n. sp. F.V. 35d; do. S.V.

36. ... distans, n.sp., F.V. 366; do. S.V.
37 & 37 b,...staurophora, n.sp., F.V.37¢; do.S.V.
38. a fulva, n. sp., F.V. 386; do. S.V.
39.

marina, n. sp., 39 b; do. S.V.

All the above are magnified 400 diameters.

48.

- Diadesmis (?) Williamsoni, F.V., 40 6; do.
S.V.

. Meridion (?) marinum, n. sp.,F.V., 41}; do.

S.Ve

. Pyxidicula cruciata, Ehr.
. Orthosira angulata, n.sp., F.V., 430; do. F.V.
- Melosira (?) ‘or Coscinodiscus (?) qu. (?) sp. (?)

Nn. sp.

. Coscinodiscus nitidus, n. sp.

punctulatus. n. sp.
concavus, Ehr.
umbonatus, n. sp.

_ (> gPAUe EVOPACAISES

t 7 “% r ‘ y
he 608. VM Jaonolliiyy 1t wi ob LF fh €
} aii W (8a 4 e

7

oh 4b oe maga [Ppp o :
7 Vv y ?
a”, ott tales algatiny') Se: ‘ ; ae ¥
' . orn oly AE FE wpe aelieryne asionclin® 6s | 78 ob idee a 8
; ; Ghee vp 7) va ngs cs yh anny 18 +e Z ¥. J ots. 7 vi - he
a as. poteliies gaselbocitnes) Ae <u aa - im Ae y.
as ae on sufalvianty |... ab =" a Ef
, : WS evasion ra. re et Fy 44 1:4 86 an
: * Ja ft Setetedew LP a V.8 of > oe: a a
ae | qaesind 00) baaiipess oma vrsde uit ILA
. my,
a if 4 ye or
‘ aS. h ee
} : Py A,
) A

Trans Roy Soc Edin F1_XI Vol X71.

ane

Ey)
2O35.
key

)
9
4

ees
OOO.
056:

eo, 2086 SOD. O0,
Boose ete cna peenan eee aie yeu
08 05 On eiaam coke, er Ser eres ee

( cVey-atk
. \

; t\ MS
AMARA

W West uaa,
RAGdel Tu

en West se

go S

»

Coscinodiscus centralis, Ehr.
_ 50. Eupodiscus subtilis, n. sp., Ralfs.
ade ae centralis, n. sp.

—_ Ralfsii (?) Sm.

EXPLANATION OF PLATE XI.

| Fig. 53. Campylodiscus angularis, n. sp.

— 54&54b,... eximius, Nn. sp.
=— 505 Gr limbatus, Bréb.

All the above are magnified 400 diameters.

*
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Trans Roy Soc Edm Pl X1.Vol 20

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EXPLANATION OF PLATE XII.

. 56. Amphiprora pusilla, n. sp., F.V., 36 6; do.| Fig. 64. Amphora nana, n. sp.
S.V. 65. ae macilenta, n. sp.

57. aan plicata, n. sp., F.V. — 66. ... angusta, n. sp.
58. oe elegans, Sm.S.V., 586; do.F.V.|— 67. ... binodis, n. sp.
59. wae lepidoptera, n. sp., F.V., 59b;|— 68&68b, ventricosa, n. sp.
do., 8.V., 59 ¢; do. peculiar} — 69. ... monilifera, n. sp.
view. —— Ore “an lineata, n. sp.
60. ee obtusa, n. sp., F.V. Sane ere Ergadensis, n. sp.
61. he maxima, Greg F.V.,61 6; do.|— %2) ~ --. levissima, n. sp.
We es rsa! pellucida, n. sp., 736; half frus-
62 & 62 b (?) complexa, n. sp., F.V. entire; tule of do.
62 ¢;do. half frustule, 62 d| — 74,74, & eae n. sp., 74 d@ ; Amphora, qu. ?
and 62 e; do. detached seg- 74, a form of A. levis ?

ments. All the above are magnified 400 diameters.
63, Amphora turgida, n. sp.

:
;
i
parce
7
a

«
Rea y" 7
i
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27
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red}
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-
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sdriel line m

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Pros sy.)

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ys ip P 7
i mM a
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a wh
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120. HORT AM ASIA :

oO BT ae 100,89 ‘ye -le edtieany renga
ie sm ’ : . va : Ne “~

t 1. a ‘pdeoily aa

hy VV oh Bae, ¥ ee” oe

Vee f GS 3 TM yt ite a

va .¥ @ yet ’

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; ‘ A # met

vite. Ve ew sprig new

Peers Se
ait : 2

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, sm Cw enh on X Ee hte j
tLe hee ' ert en - ™
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Trans .Roy.Soc.Edin Pl XMI-Vol. XXL.

Ou,

PeURhTts Eypbiteen 2152!

~,

Sn es \

adi AS

EUpsIissza2y

ii

8

TERM ROUTE STING TER

A HETLUERCRTTUTEAU TTT E tt

ry,
”
Wa MPF UN ree eeeen i iTeniyin be aan

Hy
My ~ ”
r ~ wnt
ONT Tee en erry arti ONTO ’

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of
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= cee Trererere rT

Toffen West cc.

RKC. del

76.

eee ee
78 & 785,
79.

80.

81,816, 81
c, 81d,&
81 e,

EXPLANATION

OF PLATE XIII.

tao. opr exigua, 0. sp.

dubia, n. sp.

truncata, n. sp.

oblonga, n. sp.

robusta, n. sp., 79 b and 79 c; half
frustules.

spectabilis, n. sp. ; 806; do. var. 8,
80 c; do. var. y; 80d; do. view
showing the complex structure of the
species; 80 ¢; do. detached segment.

\ ...Proteus, n. sp.

Fig. 82. ie lyrata, n. sp.

— 83.

Milesiana, n. sp.
elongata, n. sp.
quadrata, n. sp.
excisa, 0. sp.
nobilis.

Arcus, Greg.
Grevilliana, Greg.
fasciata, n. sp.
complexa, n. sp.

All fie crane are magnified 400 diameters.

|

pa

/

‘i .o wave tng a 4 St ~~

-

’

orpataal
1 se
t fae ear
2eyq
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a See) oe fo Bie
RK 4 b _ »! a t =,
y ' a s rat a

» 2 nig stodgenk’s

ea a te go piel...
1 Ss” \
“ ot oA 72 @ eho laeyet :

: a eb. . 4
Se ae PRS . qe a eset 4 be BF
BE? on (eee oT 14 Ft is it atbaedy -
¥ 1f a Wd oteaty 7
43 Wc “= OB © 4 I habonyd
ed ost » ; RUZ be ie |
7 ody tae genie 3 abhi Mts Welt

Loe bro duetadhh : om =
od / Lf
4? .2 geo é

Trans .Roy.Soc.Edm. Pl XIV Voi X21

nel

SS —————————— ee
IE IEE AE IOC

REKG.del Tuffen West sc.

Fig.

EXPLANATION

SOE PUT EY XLV,

93. Amphora acuta, n. sp. detached segment ;

98 & 98b,

-_>

99.

93 b; do. pack of similar seg-
ments.

crassa, n. sp, 94 b, 94 c, and 94d;
do. detached segments.

...pusilla, n. sp., simple and complex

views.

---pranulata, n. sp., simple and com-

plex views of two frustules;
96 f, detached segment; 96 ¢;
form qu.? allied to A. granu-
lata ?

---eymbifera, n. sp., simple and com-

plex views, 97c; detached seg-
ment of do.

-proboscidea, n. sp., simple and com-

plex views, 98c, and 98 d;
detached segments of do.
costata, Sm., detached segment.

Fig.100 & | Amphora bacillaris, n. sp., simple and
100 b, § complex views.
— 101. Navicula (?) Libellus, n. sp., 1016; do, edge
view.
— 102. Nitzschia (?) panduriformis, n. sp.
== NOS. ‘ distans, n. sp., 103 b, do. S.V.

— 104. hyalina, n. sp., 104 b, do. S.V.
== ue \Pteurosigma ? reversum, n. sp
& 1050, ; er TEN 3

— 106. Sceptroneis Caduceus, Ehr.
— 107. Synedra undulata, Greg. (Toxarium undula-
tum, Bailey). Two specimens of the

8.V., the one straight, the other arc-
uate.

Hennedyana, n. sp., S.V.
APPENDIX.

— 109. Creswellia (nov. gen.) Turris, n. sp., Arnott.
All the above are magnified 400 diameters.

— 108.

fim “baorly nitalimed wt é
' rr Jee

= aati eel ate 1
' E ay
j i
ue tee Pay LS) Ao wee! i

a pierfart;
pl A ying
4s ; yt ve at

.
_ diss ve g

ot) WP PPearever’ 1 )

a mei; p

ree ha) pers:
, adeakd eee "me
thefl + ws

fi
vf Ben odd. 7 e,

\» wa
Ait
(* ff _se@e Om He
2 if : f
i IB 5, ‘ : aS
ie ' ' lek fein ae ‘
%
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. VIX ATAL YO. MDT RAGE DEG
\ :

g
(tit dt, eplpterti ical

=.
/ vd

+

Ay L the a eeeengee Repigatnady

5 oe
10! |

dns AA
: a a | “

‘ abpan ars brio alana

prs ated iat

a

wf

d@e bes efys

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ee) | ee Ce

? ted, JT othpeip £ epee
\ , » ¥ sal

ail wipe Av fh eye ats
“8 fetincih 3 0T° oh at

u yc: Ob to Agacr
cov beth ol pita of. 400 ned oy
Fp el tete aeeeee “anie

L, ab by) oserypee bo dowin’

if hitcaryes toviewiedl a2 er ai=
hi
s
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( 543 )

XXXII.—On the Urinary Secretion of Fishes, with some Remarks on this Secre-
tion in other Classes of Animals. By Joun Davy, M.D., F.R.SS. Lond. and
Edin., &e.

(Read 2d February 1857.)

Notwithstanding the progress made of late years in animal chemistry in con-
nection with comparative anatomy, I am not aware of any observations that have
yet been published on the urinary secretion of fishes. The neglect of this inquiry
probably has arisen from several circumstances,—the nature of the element in-
habited, the peculiarities of the urinary organs, the difficulty of collecting the
matter voided, and its having no well-marked distinctive qualities obvious to the
senses.

For some years, as leisure and opportunities offered, I have given attention
to the subject, and in the paper which now I have the honour to submit to the
Society, [beg to communicate the observations I have made. Few and im-
perfect as these are, they are given mainly with the hope of attracting notice to
the inquiry and of inducing others more favourably situated to engage in its
prosecution.

The fishes I have examined in search of their urinary secretion have been the
following,—the salmon, sea-trout, charr, common trout, pike, and perch; the
skate, ling, conger, cod, pollack, haddock, turbot, bream, and mackerel.

Of these the salmonide, pike, perch, ling, and ray, have a small urinary blad-
der; and in all but the last communicating directly with the kidneys. In the
last mentioned, the ray, the communication appears to be indirect, after the
manner observable in some of the batrachians, in which the ureters terminate in
the cloaca.

The other fishes named seem to be destitute of a urinary bladder, or, if pos-
sessed of one, it was so small as to have escaped observation. The ureter in
these, when distinct, was found to terminate near the verge of the anal aperture ;
in several instances it was so large and dilated as to serve the place of a bladder.

In the small urinary bladder of the salmonide (so small as to be little more
than rudimentary), I have never found any fluid collected. In the bladder of a
trout (Salmo fario) taken in June, in Windermere, when in highest condition,
there was seen a little whitish mucus-like matter. Tested by nitric acid and heat
properly graduated, it became yellow, without the slightest purplish tinge, indi-
cative of the presence of lithic acid.

The urinary bladder of the perch (Perca fluviatilis) is larger, and internally pli-
cated and spongy, and has been found to contain a fluid. In that of one,—a fish,

VOL. XXI. PART IV. 1G

544 DR DAVY ON THE URINARY SECRETION OF FISHES.

weighing about a pound and a half, taken in the same lake, and in the same
month as the trout,—there was a little mucus-like matter suspended in its fluid
contents. The fluid was rendered turbid by admixture with alcohol. It cleared
on rest, from the subsidence of the precipitated matter. The clear solution, de-
canted and evaporated gently, yielded crystals approaching in form those afforded
by a weak solution of muriate of ammonia similarly treated. Redissolved on the
addition of a minute portion of nitric acid, and again evaporated, crystalline
plates were obtained very like those of the nitrate of urea. Subjected to the
temperature required for detecting the presence of lithic acid, the result was ne-
gative,—the hue produced was yellow, without the slightest tinge of purple ;—
and the mucus-like matter similarly tested afforded a like result.

The urinary bladder of the pike (sox lucius) is very small. I have always
found itempty. In the ureter* of one of about two pounds, taken in Winder-
mere in May, a few delicate yellowish flakes were detected. These, under the
microscope, exhibited no characteristic appearance; acted on by dilute nitric
acid, however, they were in great part dissolved; and when evaporated with a
graduated heat to dryness on a support of thin glass, the purple stain distinc-
tive of lithic acid was produced, and it was so strong, that it coloured a propor-
tionally large quantity of water.

The ling (Lota molva) has a comparatively large urinary bladder. From the
bladder of one,—a fish of about four feet long, taken in the Mount’s Bay, in Corn-
wall, in the month of June,—a small quantity, about a drachm, of nearly colour-
less fluid was obtained, in which a few flakes resembling lymph were sus-
pended. These flakes were tested for lithic acid, but with a negative result.
The fluid was coagulated by heat, by nitric acid, and by alcohol, indicating the
presence of a notable proportion of albumen. The alcoholic solution, after the
separation of the precipitated albumen, evaporated to dryness at a low tempera-
ture, yielded, after the addition of a minute portion of nitric acid, crystals which,
seen under the microscope—they were too small to be seen without this aid—
resembled so closely those of nitrate of urea, that I had little hesitation in coming
to the conclusion that they were this compound.

The common ray (fava batts) is provided with two small bladders, each dis-
tinct, and neither of them communicating directly with the kidneys. In a male,
examined in November, they were found distended with a nearly colourless lim-
pid fluid, in which, placed under the microscope, were seen many small globules,
and a few spermatozoa. This fluid, evaporated at a low temperature, yielded a
colourless residue, in which were minute crystals of common salt; and, acted on

* Professor Owen, in his Lectures on the Comparative Anatomy of the Vertebrate Animals
(Part i., p, 228), describes the bladder of the pike as communicating with the kidneys by a single
common ureter; in most instances I have found the communication such, but in one fish, one of
six pounds, it was by two.

DR DAVY ON THE URINARY SECRETION OF FISHES. 545

by alcohol and nitric acid, indications were afforded of the presence also of a little
albumen and urea, but without any trace of lithic acid.

Of the fishes before named, destitute of a urinary bladder, the ureter, in the
instance of the haddock (Morrhua eglefinus), of the cod (Morrhua vulgaris), of
the pollack (Merlangus pollachius), of the turbot (Rhombus maximus), was found
so capacious, that it might answer the purpose of a receptacle or bladder. In
each its inner surface was wet; but only in one, that of the turbot, was there any
fluid collected. The quantity obtained, by cutting out the duct, after a ligature
had been. passed above and below, was about ten drops. It was colourless, not
quite clear, and had suspended in it a few white flakes. These were not dissolved
by nitric acid, nor did they, when the acid was evaporated by heat, afford any
the slightest indications of lithic acid. The residue was yellow; nor could urea
be detected in the minute portion of fluid.

Of the bream (Pagillus centrodontus), the ureter is narrow, and of little ca-
pacity; as is also that of the conger (Conger vulgaris), and that of the mackerel
(Scomber scombrus). Of all three the ureter was found merely moist—wet—as if
a fluid had passed; in neither could any solid matter be detected. At the ter-
mination of the ureter of the bream a minute portion of whitish matter was —
seen adhering, suggesting lithate of soda or ammonia, but not confirmed when
tested; for, when acted on by nitric acid and heat, the colour acquired was yel-
low, without the slightest tinge of purple.

I may mention, generally, that in most ofthe fishes, the names of which have
been given, I did not omit examining the cloaca, but with results so unsatisfac-
tory, that they might be said to have been negative. Often there was an ap-
pearance as if of the presence of an alkaline lithate; but, when tested, it was
found to be different, and the matter chiefly intestinal excrement. In the in-
stance of one only, and that a sea-trout (Salmo trutia), was a trace of urea indi-
cated, judging from the form of the minute microscopic crystals obtained on eva-
poration, after treatment with alcohol and nitric acid.

Imay also mention, generally, that in each fish I carefully inspected the struc-
ture of the kidneys; but without success as to the finding of any matter conspi-
cuous to the eye, such as is commonly seen in the same organs in the instance of
serpents and lizards, viz., the opaque lithate.

In one instance only, that of the haddock, have I examined these organs che-
mically. The result, too, was negative. The trial was made, first by digesting
the kidneys in alcohol, decanting the clear spirit, evaporating it at a low tempe-
rature, and to the concentrated extract obtained adding nitric acid; secondly,
by digesting the organs with aqua ammonia, filtering the solution, and testing
the little extract obtained by nitric acid and heat.

If any conclusions are permissible from the preceding few and imperfect ob-
servations, I would venture to submit the following :—1s¢, that the urinary secre-

546 DR DAVY ON THE URINARY SECRETION OF FISHES.

tion of fishes is very limited as to quantity; 2dly, that it is commonly liquid ;
3dly, that the nitrogenous compound eliminated is variable——either urea or a
lithate (the latter probably very seldom), or some nearly allied compound of
azote.

A brief glance at this secretion in other classes of animals may here not be
out of place, as bearing on these conclusions. I need not dwell on the import-
ance of the urinary secretion, denoted by its generality, and how, in all the great
divisions of the animal kingdom in which it has hitherto been examined, viz.,
the mammalia, birds, reptiles, insects, spiders, the mollusca, it has been found to
consist chiefly of compounds abounding in nitrogen, authorizing the commonly-
received conclusion that the secerning organs are depurating in their function,
and the main channel by which the excess of this element (nitrogen) is removed
from the system.

The differences however compatible with this intent, — differences in the
nature of the secretion,—are not a little remarkable. Iallude merely to the qua-
lity—to the chemical ingredient; and they seem to be regulated more by the
structure of the urinary apparatus, or secerning vessels, than by any other cir-
cumstance, not even excepting the kind of diet, whether animal or vegetable, or
an admixture of the two.

In the mammalia, provided with an ample urinary bladder, the normal secre-
tion is seen to be entirely liquid, and the principal ingredient, so far as it has yet
been determined, always soluble urea: Such it has been found to be in man; such
in the carnivorous animals; such in the herbivorous; with the addition, in that
of some of them, of the hippuric acid.

In birds, on the contrary, and in those reptiles which, like them, are desti-
tute of a urinary bladder, viz., snakes and lizards, invariably the secretion, judg-
ing from my own pretty extended experience, is chiefly solid,—a soft, plas-
tic one, owing its consistence to admixture with water, and composed princi-
pally of lithate of ammonia and lithic acid. Yet in others of the latter class,
which have a receptacle corresponding to the urinary bladder, and destined to
hold the secretion,* the secretion is fluid, as in the instance of the toads and
frogs; and the nitrogenous matter eliminated is again the soluble urea. The
same remark applies to the tortoises, with this difference, that sometimes, though
their food be vegetable solid matter, flakes of a lithate are occasionally found
suspended in the fluid contents of their urinary bladder.

In insects, also in spiders and scorpions, all which, it is presumed, have no

* Whether this receptacle be considered,—as it is by Mr T. R, Jones, in his General Outlines of
the Animal Kingdom (p. 585)—the unobliterated remains of the allantois, or a true urinary bladder,
its primary use, I apprehend, can hardly now be questioned, since all the later examinations that
have been made of the fluid contained in it prove that in composition it is urinous, as stated above:
whether, in the instance of the frog, it may not subserve to aid, as some distinguished physiologists
suppose, by transpiration in keeping the skin duly moist, is open to question.

DR DAVY ON THE URINARY SECRETION OF FISHES. 547

receptacle for the secretion but the cloaca, we find it in consistence analogous to
that of birds, snakes, and lizards, a soft solid; in insects, as far as my observa-
tions have extended, and they have been numerous,* it is composed chiefly of an
alkaline lithate; but in the others, the spiders and scorpions, of guanine.t

Of the secretion in the mollusca, also without a urinary bladder, I can ven-
ture to say little. In two instances I have found it to be lithic acid; the indivi-
duals in the excrement of which I detected this compound were our common
slug (Lima agrestis), and the large snail of Tobago (Helix oblonga ?).

Of animals lower in the organic scale, the only ones I have examined with
any positive result have been two of the Myriapoda,—the common centipede of
the West Indies (Scolopendra morsitans), and our millipede (Julus terrestris), the
one voracious, feeding on insects, the other feeding on vegetable matter. In the
mixed excrement of the scolopendra, lithate of ammonia in abundance was de-
tected ;+ but in that of the millipede, merely a trace of lithic acid.

In this brief notice of the urinary secretion in the several classes of animals
mentioned, I have, as I premised, taken notice only of its principal ingredient; |
would further beg to remark, that in stating that the quality of the secretion is —
independent of the quality of the food, I would wish to be understood as not
holding the opinion that it is not in some measure modified by the kind of food,—
especially as regards the quantity of matter eliminated. As might be expected,
the larger the proportion of nitrogen in the food consumed, the larger, ceteris pa-
ribus, seems to be the quantity of the nitrogenous compound excreted, and vice
versa. Moreover, when the food is entirely vegetable, there seems to be in some
instances a tendency towards the production of the hippuric acid rather than of
the lithic. MM. Maenon and Lenmann have found this compound in the urine of
the tortoise feeding on lettuce;§ and have found it mixed with lithic acid in the
urine of caterpillars feeding exclusively on vegetables,—a result which accords
with my own experience.

In the animal economy we see commonly, amongst the different classes of
animals, a certain relation and accordance of functions conducive in action to
the elaboration and wellbeing of each individual structure. Such a relation is
manifest between the kidneys and the lungs; the former the depurator of nitro-

* Trans, Ent. Society, vol. iii., N. 8.

t+ When I first examined the excrement of spiders and scorpions in 1847-1848, operating on
minute quantities, I inferred that it consisted chiefly of xanthic oxide : Guanine was not then known.
Since its discovery by Bopo Uneer, I have re-examined portions of the excrement of each, which I
brought from the West Indies, and have satisfied myself that the principal ingredient of both is this
compound; I have also found it, in accordance with the researches of Witt and Gorup-Busanez,
to form the chief portion of the excrement of our spiders, The very low degree in which this excre-
ment is soluble in cold muriatic acid may account for its having been first confounded with the
xanthic oxide.

t Edin. Phil. Jour., vol. xlv. p. 383.
§ Leumann’s Physiological Chemistry, vol. ii., p. 458.

VOL. XXI. PART IV. 7H

548 DR DAVY ON THE URINARY SECRETION OF FISHES.

gen, as much as the latter is of carbonic acid. How strongly is this exemplified
in birds ;—of high temperature, consuming much atmospheric air, evolving much
carbonic acid,—their urinary secretion, also, is remarkably abundant, and abound-
ing in nitrogen.* And in other classes of animals, such as insects in their seve-
ral stages, such as serpents and lizards, and the hybernating ones of different
classes, whether active or torpid, a like accordance, though perhaps not so
strongly shown, is yet clearly observable.

Reasoning hence, guided by analogy, might it not be expected that in the in-
stance of fishes, inasmuch as their temperature is low, and the quantity of car-
bonic acid evolved small, that their urinary secretion also would be small—pro-
portionally small? And, granted that it is so, as the results of the experiments
described would seem to indicate, does it not lead to another conclusion, viz.,
that subsisting, with few exceptions, exclusively on animal food, this their food,
under the influence of a high digestive power, is almost entirely assimilated, and
that no more is expended on the urinary secretion than is requisite to balance
the small amount consumed in carrying on the aérating process? And if this be
admitted, does it not help to explain some of their peculiarities,—their remark-
able rapidity of growth when supplied with abundance of food,—their little
waste of substance when sparingly supplied, and their long endurance without
loss of life, under a total, or nearly total, privation of aliment? :

The history of the salmon and its congeners, which of late years has been so
carefully and successfully studied, might be adduced in illustration,—exem-
plifying, 1s¢, The great activity and power of the organs carrying on the digestive
functions,—the stomach itself of the captured fish, with the parietes adjoining,
being found more or less dissolved by the action of the gastric juice in the short
space of a few hours, and in being always found empty in the migrating fish ;
2dly, The extraordinary increase in weight during the short sojourn of the young
salmon in the sea, when, without stint of food, it passes from the smolt stage of
growth to that of the grilse; and, 3d/y, The comparatively very slow growth of
the young salmon in its parr stage, during the months of winter and early spring,
when its food is scarce.

LesketH How, AmpxesipeE, Dec. 1, 1856.

* I may mention as an instance the swallow, feeding like the trout, when the food of the latter
is chiefly insects, and, as regards the secretion in question, showing a remarkable difference. From
the nest of a pair I had an opportunity of observing, the young of which were only a few days old,
the droppings on a flag-stone. beneath, in one day, were as many as forty-five; those collected and
dried thoroughly weighed 78-3 grains ; the following day, the droppings were seventy. They con-
sisted chiefly of lithate of ammonia with a little urea, and of the indigestible remains of insects,—the
urinous portion by far the largest. The excrement, it may be inferred, was chiefly from the young
birds, as the parent birds were almost constantly on the wing providing food. How large in quan-
tity was this excrement in comparison with the bulk of the birds! I have found an old swallow to
weigh only about 300 grains, and when thoroughly dried no more than 105 grains, so that the
amount of excrement in two days exceeded considerably in weight one of the old birds!

( 549 )

XXXIII.—On the Minute Structure of Involuntary Muscular Fibre. By Josrru
Lister, Esq., F.R.C.S. Eng. and Edin., Assistant-Surgeon to the Royal
Infirmary, Edinburgh. Communicated by Dr CurisrTison.

(Read 1st December 1856.)

It has been long known that contractile tissue presents itself in the human
body in two forms, one composed of fibres of considerable magnitude, and there-
fore readily visible under a low magnifying power, and marked very character-
istically with transverse lines at short intervals, the other consisting of fibres
much more minute, of exceedingly soft and delicate aspect, and destitute of trans-
verse striee. The former variety constitutes the muscles of the limbs, and of all
parts whose movements are under the dominion of the will; while the latter
forms-the contractile element of organs, such as the intestines, which are placed
beyond the control of volition. There are, however, some exceptions to this
general rule, the principal of which is the heart, whose fibres are a variety of the
striped kind.

Till within a recent period the fibres of unstriped or involuntary muscle were
believed to be somewhat flattened bands of uniform width and indefinite length,
marked here and there with roundish or elongated nuclei; but in the year 1847,
Professor Konuiker of Wurzburg announced that the tissue was resolvable into
simpler elements, which he regarded as elongated cells, each of somewhat flat-
tened form, with more or less tapering extremities, and presenting at its central
part one of the nuclei above mentioned. These “ contractile’ or “ muscular
fibre-cells,”’ as he termed them, were placed in parallel juxtaposition in the tissue,
adhering to each other, as he supposed, by means of some viscid connecting sub-
stance. In the following year the same distinguished anatomist gave a fuller
account of his discovery in the Ist volume of the Zeitschrift fir Wissenschaftliche
Zoologie, and described in a most elaborate manner the appearances which the
tissue presented in all parts of the body where unstriped muscle had been pre-
viously known to occur, and also in situations, such as the iris and the skin,
where its existence had before been only matter of conjecture, but where the cha-
racteristic form of the fibre-cells, and of their << rod-shaped” nuclei had enabled
him to recognise it with precision. Confirmations of this view of the structure
of involuntary muscular fibre were afterwards received from various quarters,
one of the most important being the observation made in 1849 by RercueErt, a
German histologist, that dilute nitric or muriatic acid loosens the cohesion of the
fibre-cells, and enables them to be isolated with much greater facility. In 1852
I wrote a paper ‘‘ On the Contractile Tissue of the Iris,” published in the Micro-

VOL. XXI. PART IV. 71

550 MR LISTER ON THE MINUTE STRUCTURE OF

scopical Journal, in which I gave an account of the involuntary muscular fibre
contained in that organ in man and some of the lower animals, stating that the
appearances I had met with corresponded exactly with KoLiixer’s descriptions,
and illustrating my remarks with careful sketches of several fibre-cells from the
human. iris, isolated by tearing a portion of the sphincter pupillee with needles in
a drop of water. In 1853, another paper by myself appeared in the same Jour-
nal, “‘ On the Contractile Tissue of the Skin,” confirming KoLLIKEr’s recent dis-
covery of the “arrectores pili,” and describing the distribution of those little
bundles of unstriped muscle inthe scalp. These and other investigations into the
involuntary muscular tissue convinced me of the correctness of KoLLIKER’s obser-
vations, and led me to regard his discovery as one of the most beautiful ever
made in anatomy; and this is now, I believe, the general opinion of histologists.
Still, however, there are those who are not yet satisfied upon this subject. In
Miituer’s Archives for 1854, is a paper by Dr J. F. Mazonn of Kiew, in which the
author expresses his belief that the muscular fibre-cells of KoLLIKER are created
by the tearing of the tissue in preparing it, and denies the existence of nuclei in
unstriped muscle altogether ; but he gives so very obscure an account of his own
ideas respecting the tissue, that his objections seem to me to carry very little
weight, more especially as the appearances which he describes require, according
to his own account, several days’ maceration of the muscle in acid for their
development. In June of the present year (1856), Professor Exiis of University
College, London, communicated to the Royal Society of London a paper entitled
“Researches into the Nature of Involuntary Muscular Fibre.” In the ab-
stract given in the “ Proceedings” of the Society, recently issued, we are informed
that, ‘having been unable to confirm the statements of Professor KoLLIKER re-
specting the cell-structure of the involuntary muscular fibre, the author was In-
duced to undertake a series of researches into the nature of that tissue, by which
he has been led to entertain views as to its structure in vertebrate animals, but
more especially in man, which are at variance with those now generally received.”
In the “summary of the conclusions which the author has arrived at,” we find the
following: “In both kinds of muscles, voluntary and involuntary, the fibres are
long, slender, rounded cords of uniform width ....’’ ‘“ In neither voluntary nor
involuntary muscle is the fibre of the nature of a cell, but in both is composed
of minute threads or fibrils. Its surface-appearance, in both kinds of muscle,
allows of the supposition that in both it is constructed in a similar way, viz.,
of small particles or “ sarcous elements,” and that a difference in the arrangement
of these elements gives a dotted appearance to the involuntary, and a transverse
striation to the voluntary fibres.” “On the addition of acetic acid, fusiform or
rod-shaped corpuscles make their appearance in all muscular tissue ; these bodies,
which appear to belong to the sheath of the fibre, approach nearest in their charac-
ters to the corpuscles belonging to the yellow or elastic fibres which pervade va-

INVOLUNTARY MUSCULAR FIBRE. 551

rious other tissues; and from the apparent identity in nature of these corpuscles
in the different textures in which they are found, and especially in voluntary, as
compared with involuntary muscle, it is scarcely conceivable that in the latter
case exclusively they should be the nuclei of oblong cells constituting the proper
muscular tissue.”

Mr Ets, then, agrees with Mazonn in believing that the tapering fibre-cells
of KoLurKkeEr owe their shape to tearing of the tissue; and he regards the nuclei as
mere accidental accompaniments of the proper muscular structure, probably be-
longing to the sheath of the fibres, which, according to him, are of rounded form
and uniform width.

The distinguished position of Mr Euuis as an anatomist makes it very desirable
that his opinion on this important subject should be either confirmed or refuted,
and the object of the present paper is to communicate some facts which have re-
cently come under my observation, and which, I hope, may prove to others as
unequivocally as they have done to myself, the truth of KoLLiKer’s view of this
question.

In September last, being engaged in an inquiry into the process of inflamma-
tion in the web of the frog’s foot, I was desirous of ascertaining more precisely —
the structure of the minute vessels, with a view to settling a disputed point re-
garding their contractility.

Having divided the integument along the dorsal aspect of two contiguous toes,
I found that the included flap could be readily raised, so as to separate the layers
of skin of which the web consists, the principal vessels remaining attached to the
plantar layer. Having raised with a needle as many of the vascular branches as
possible, I found, on applying the microscope, that they included arteries of ex-
treme minuteness, some of them, indeed, of smaller calibre than average capilla-
ries. A high magnifying power showed that these smallest arteries consisted of
an external layer of longitudinally arranged cellular fibres in variable quantity, an
internal exceedingly delicate membrane, and an intermediate circular coat, which
generally constituted the chief mass of the vessel, but which proved to consist of
neither more nor less than a single layer of muscular fibre-cells, each wrapped in
a spiral manner round the internal membrane, and of sufficient length to encircle
it from about one-and-a-half to two-and-a-half times. Fig. 18. (Plate XV.) repre-
sents one of these vessels as ‘seen under a rather low power, and shows the ge-
neral spiral arrangement of the fibres of the middle coat. Fig. 19. is a camera
lucida sketch of the same artery highly magnified, in which I have for the most
part traced the outline of the fibres on the nearer side of the vessel only, but
one fibre-cell is shown in its entire length wrapped round nearly two-and-a-half
times in a loose spiral. In some other vessels the muscular elements were
arranged in closer spirals, as in figs. 20 and 21. They are seen to have
more or less pointed extremities, and are provided with an oval nucleus at

B52 MR LISTER ON THE MINUTE STRUCTURE OF

their broadest part, discernible distinctly, though somewhat dimly, without the
application of acetic acid. The tubular form of the vessels enables the observer,
by proper adjustment of the focus, to see the fibre-cells in section; they are then
observed to be substantial bodies, often as thick as they are broad, though the
latter dimension generally exceeds the former. Here and there a nucleus is so
placed in the artery as to appear in section with the fibre-cell, as shown in figs.
20, 22, and 23. The section of the nucleus is in such cases invariably found sur-
rounded by that of the substance of the fibre-cell, though occasionally placed ec-
centrically in it. From the circular form of its section the nucleus appears to be
cylindrical. These fibre-cells are from =}, inch to =; inch in length, from
sis; inch to ;4, inch in breadth, and about ;2,, inch in thickness, mea-
surements on the whole rather greater than those given by Koiiixer for the hu-
man intestine, the chief difference being that in the frog’s arteries they are some-
what broader and thicker.

Now, the middle coat of the small arteries is universally admitted to be com-
posed chiefly of involuntary muscular fibre; but in the vessels just described it
consists of nothing whatever else than elongated, tapering bodies, corresponding
in dimensions with KoLuikeEr’s fibre-cells, and each provided with a single cylin-
drical nucleus embedded in its substance. Considering, then, that no tearing of
the tissue had been practised in the preparation of the objects, but that the parts
were seen undisturbed in their natural relations, it appeared to me that the sim-
ple observation above related settled the point at issue conclusively.

It was, however, suggested to me by an eminent physiologist, that the various
forms in which contractile tissue occurs in the animal kingdom forbid our
drawing any positive inference regarding the structure of human involuntary
muscle from an observation made on the arteries of the frog. Being anxious
to avoid all cavil, and understanding that Mr Extts’s researches had been
directed chiefly to the hollow viscera, I thought it best to examine the tissue
in some such organ. For this purpose I obtained a portion of the small intes-
tine of a freshly killed pig, selecting that animal on account of the close ge-
neral resemblance between its tissues and those of man. The piece of gut hap-
pened to be tightly contracted, and on slitting it up longitudinally, the mucous
membrane, which was thrown into loose folds, was very readily detached from the
subjacent parts. I raised one of the thick, but pale and soft fasciculi of the cir-
cular coat, and teased it out with needles in a drop of water, reducing it without
difficulty to extremely delicate fibrils. On examining the object with the micro-
scope, I found that it was composed of involuntary muscular fibre, almost entirely
unmixed with other tissue, reminding me precisely of what I had seen in the hu-
man sphincter pupillee, except that the appearances were more distinct, espe- 7
cially as regards the nuclei, which were clearly apparent without the application
of acetic acid. Several of the fibre-cells were isolated in the first specimen I ex-

INVOLUNTARY MUSCULAR FIBRE. 553

amined, each one presenting tapering extremities about equidistant from a single
elongated nucleus. The fibre-cells were of soft and delicate aspect, generally ho-
mogeneous or faintly granular, with sometimes a slight appearance of longitudinal
strize, such as is represented in fig. 4.

I had now seen enough to satisfy my own mind that the involuntary muscu-
lar fibre of the pig’s intestine was similarly constituted with that of the human
iris and the frog’s artery: but before throwing up the investigation, I thought it
right to examine carefully some short, substantial-looking bodies of high refractive
power, which at first sight appeared, both from their form and the aspect of
their constituent material, totally different in nature from the rest of the tissue.
Several of these bodies are represented in figs. 10-15. Each is seen to be of
somewhat oval shape, with more or less pointed extremities, and presents
several strongly marked, thick, transverse ridges upon its surface; and each,
without exception, possesses a roundish nucleus whose longer diameter lies across
that of the containing mass. Yet between these bodies and the long and deli-
cate homogeneous fibre-cells above described, every possible gradation could
be traced. Figs. 8 and 9, are somewhat longer than those just indicated, and
are also remarkable for their regularity. In figs. 5, 6, and 7, are repre- —
sented fibre-cells of considerable length, marked here and there with highly
refracting transverse bands, in the intervals of which they are of soft and de-
licate aspect. In several cells one half was short, with closely approxima-
ted rug, the other half long and homogeneous. Hence it was pretty clear
that the appearances in question were due to contraction of the fibre-cells,
and that the shortest of these bodies were examples of an extreme degree of
that condition; their substantial aspect and considerable breadth being produced
by the whole material of the long muscular elements being drawn together into
so small a compass. The rounded appearance of the nuclei was accounted for
by supposing either that they had themselves contracted, or that they had been
pinched up by the contracting fibres, of which explanations the latter appears
the more probable.

In order to place the matter if possible beyond doubt, I prepared two conti-
guous portions of the circular coat of a contracted piece of intestine in different
ways; the one by simply cutting off a minute portion with sharp scissors, so as
to avoid as much as possible any stretching of the tissue, the other by purposely
drawing out a fasciculus to a very considerable length, and then teasing it with
needles. In the former preparation, the fibre-cells appeared all of them more or less
contracted, except in parts where the slight traction inseparable from any mode of
preparation had stretched the pliant tissue, which in the fresh state appears to
yield as readily to any extending force as does a relaxed muscle of a living limb.
In the other object, where the tissue had been purposely stretched, most of the
fibre-cells were extended, and possessed elongated nuclei. Here and there one

VOL. XXI. PART Iv. 7K

554 MR LISTER ON THE MINUTE STRUCTURE OF

would be seen of excessive tenuity, scarcely broader at its thickest part than the
nucleus, looking, under the highest magnifying power, like a delicate thread of
spun glass. To how great a length the fibre-cells admit of being drawn out in
this way without breaking I cannot tell. Fig. 1 represents a portion of such a
fibre with the contained nucleus. Among these extended fibres, however, there
lay, here and there, an extremely contracted one, the result, | have no doubt, of
the irritation produced by the needles upon the yet living tissue. In order to
guard against this source of fallacy, I kept a piece of contracted gut 48 hours,
and then examined two contiguous parts of the circular coat in the way above
described. The muscle was much less readily extended than in the fresh state,
and I found that, where stretching of the tissue had been avoided as much
as possible, it was composed entirely of fibre-cells marked with transverse
ridges of varying thickness and proximity; a minute fibril having, under a
rather low power, the general aspect represented in fig. 17. But I saw no distinct
examples of the extreme degree of contraction so frequent in muscle from the
same piece of intestine in the fresh state. This confirmed my suspicion that
the latter had been induced by the irritation of the mode of preparation. On
the other hand, a fully stretched fasciculus showed its fibres everywhere des-
titute of transverse rug, so that the point was now distinctly proved.
KouuikErR, in his original article in the Zedschrift fiir Wzssensehaftliche
Zoologie, figured some long fibre-cells with transverse lines upon them,—
“knotty swellings,” as he termed them, which he supposed probably due to con-
traction, and he repeats this hypothesis in the part of his Mvckroskopische
Anatomie, published in 1852. The proof of the correctness of this idea is now,
I believe, given for the first time.

The bearings of these observations on the main question respecting the
‘structure of involuntary muscular fibre are obvious and important. In the
first place, if the short, substantial bodies were mere contracted fragments of
rounded fibres of uniform width, we should expect them to be as thick at their
extremities as at the centre, instead of which they are always more or less
tapering, and often present a very regular appearance of two cones applied to
each other by their bases. Secondly, the uniform central position of the nuclei
in the contracted fibres, proves clearly that the former are no accidental ap-
pendages of the latter, to which it seems difficult to refuse KoLLIKER's appel-
lation of cells.

The effect of acetic acid on the involuntary muscular tissue is to ren-
der the fibres indistinct, but the nuclei more apparent; and if this reagent
be applied to a piece of contracted muscle, many of the nuclei are seen to
be of more or less rounded form. The deviation of the nuclei from the
“ rod-shape” has hitherto been a puzzling appearance, but is now satisfactorily
accounted for.

INVOLUNTARY MUSCULAR FIBRE. 555

In examining a fasciculus that had been fully stretched, 48 hours after death,
I met with several good specimens of isolated fibre-cells, two of which are repre-
sented in figs. 2and 3. I would draw particular attention to the delicate, spi-
rally-twisted extremities of the fibre-cell 3, such as no tearing of a continuous
fibre could possibly have produced. Though these fibres are very long, yet we have
no reason to believe that anything near the extreme degree of extension has been
attained in them, and we cannot but contemplate with amazement the extent of
contractility possessed by this tissue.

In fig. 16 is represented a portion of a fibre-cell curled up, which has been
introduced for the sake of the clear manner in which it shows the position of the
nucleus embedded in it. Just as in the case of the fibres wrapped round the arte-
ries of the frog’s foot, this cell might be seen in section by proper adjustment, and
that section is observed to be oval; proving that the fibre is not round, but some-
what flattened. It happens that the nucleus appears at this point; its section is
circular, and is surrounded on all sides by the substance of the cell.

The pig’s intestine seems to be a peculiarly favourable situation for the inves-
tigation of unstriped muscle. Judging from KoLuIKEr’s measurements, the fibres
appear to be of much larger size there than in the same situation in the human
body. The length of the fibre-cell 3 is 3; inch. The fibre 2 is imperfect at one extre-
mity ; but, taking the double of the distance from its pointed end to the nucleus,
its length is #; inch. These measurements are between three and four times
greater than any which Professor KoLuiKErR has given for the human intestine,
and considerably exceed the length of the ‘colossal fibre-cells’’ which he describes
as occurring in the gravid uterus. The individual fibre-cells, with their
nuclei and transverse markings, if they have any, are quite distinctly to be seen
with one of Smirx and Becx’s x object-glasses. But in order to examine their
structure minutely, a higher power is required: that which I use is a first-rate
yz, made several years ago by Mr Powett of London. All the figures in Plate XV.,
except 17 and 18, are from camera lucida sketches, reduced to the same scale.
The principal measurements of the fibre-cells from the pig’s intestine are as
under :—

Length of fibre-cell, 3, : : : A : = tag alelss
Breadth of ditto, : ; : : : . ao”
Length of nucleus of ditto, 5 j : ‘ , ae
Breadth of ditto, : 3 2 ; ‘ shea a8
Breadth of fibre-cell, 16, . : . : : oiler ting
Thickness of ditto, 2 . ; : : a
Length of fibre-cell, 13, . , ; , P eiiats
Breadth of ditto, : : , : ei i
Longitudinal measurement of nucleus of ditto, vif Y
Transverse, ditto, : : ead
Length of fibre-cell, 15, : : ; . = J

556 MR LISTER ON THE MINUTE STRUCTURE OF

Hence it appears that the length of the most contracted fibre-cell is the same as
that of the nucleus of an extended one. The fibres vary somewhat in breadth,
independently of the results of contraction. Thus, one in the extended condition
which I sketched, but which is not here shown, measured only —+— inch across.
The nuclei of the uncontracted fibres are very constantly of the same length, and
are good examples of the rod-shape to which Kouuixer has directed particular
attention. They always possess one or two nucleoli, and have often a slightly
granular character; occasionally, as in fig. 21, they present an appearance of
transverse markings. One frequently sees near the nucleus of a fibre that has
been artificially extended from the contracted state, an appearance of a gap in
the substance of the cell, forming a sort of extension of the nucleus, as if the fibre
generally had been stretched more completely than the nucleus: an example of
this is presented by fig. 7. Mr Exuis lays great stress on a dotted appearance
which he considers characteristic of involuntary muscular fibre. I must say I
agree with KoLiiker in finding the fibre-cells, for the most part, homogeneous
when extended, or faintly marked with longitudinal striz.* No doubt dots are
present in abundance; but these, so far as I have observed them in the pig’s
intestine, are distinctly exterior to the fibres, though adherent to their surface;
and I suspect them to be little globules of a tenacious connecting fluid. That
the fibre-cells do stick very tightly together, may be seen by drying a minute
portion of the tissue, after which they will be found shrunk, and slightly sepa-
rated from one another, but connected more or less by minute threads.

To sum up the general results to which we are led by the facts above men-
tioned. It appears that in the arteries of the frog, and in the intestine of the
pig, the involuntary muscular tissue is composed of slightly-flattened elongated
elements, with tapering extremities, each provided at its central and thickest part
with a single cylindrical nucleus embedded in its substance.

Professor KoLLIKErR’s account of the tissue being thus completely confirmed in
these two instances, and the description here given of its appearance in the arte-
ries of the frog’s foot being an independent confirmation of the general doctrine,
there seems no reason any longer to doubt its truth.

* The longitudinal striz above referred to, are probably due to a fine fibrous structure in
the substance of the fibre-cells, When in London, last Christmas, I had, through the kindness
of Dr Suarrey, the opportunity of examining a specimen of muscle from the stomach of a rabbit,
which he had prepared after Rercuert’s method. The nitric acid had not only detached the
fibre-cells from one another, but also brought out very distinctly in each muscular element the
appearance of minute parallel longitudinal fibres, which seemed to make up the entire mass of
the fibre-cell except the nucleus. In a plate accompanying the paper on the Iris, before re-
ferred to, I.gave figures of some fibre-cells with distinct granules arranged in longitudinal and
transverse rows. This appearance, which, however, so far as my experience goes, is exceptional,
and is hardly sufficiently marked~to deserve the appellation “ dotted,’ is probably caused by une-
qual contractions in the constituent material—_2d April 1857.

INVOLUNTARY MUSCULAR FIBRE. 557

It further appears, that in the pig’s intestine the muscular elements are, on
the one hand, capable of an extraordinary degree of extension, and, on the other
hand, are endowed with a marvellous faculty of contraction, by which they may be
reduced from the condition of very long fibres to that of almost globular masses
In the extended state they have a soft, delicate, and usually homogeneous aspect,
which becomes altered during contraction by the supervention of highly refract-
ing transverse ribs, which grow thicker and more approximated as the process
advances. Meanwhile, the “ rod-shaped” nucleus appears to be pinched up by
the contracting fibre till it assumes a slightly oval form, with the longer diame-

ter transversely placed.

I will only further remark, that these properties of the constituent elements of
involuntary muscular fibre explain, in a very beautiful manner, the extraordi-
nary range of contractility which characterizes the hollow viscera.

EXPLANATION OF PLATE XV.

Fig. 1 represents part of a fibre-cell from the pig’s intestine, drawn out into a very fine thread.

Figs. 2 and 3, fibre-cells from the same situation, considerably extended.

Fig, 4, fibre-cells exhibiting faint longitudinal striation.

Figs. 5, 6, and 7, fibre-cells imperfectly contracted.

Figs. 8 and 9, small fibre-cells considerably contracted.

Figs. 10, 11, 12, 13, 14 and 15, fibre-cells extremely contracted.

Fig. 16, a fibre-cell curled up, showing the position of the nucleus embedded in its substance.

Fig. 17, part of a moderately contracted fasciculus of unstriped muscle from the pig’s intestine,
as seen under a rather low magnifying power.

Fig. 18, a small artery from the frog’s web, under a rather low magnifying power.

Fig 19, part of the same vessel highly magnified, showing the spiral arrangement of the mus-
cular fibre-cells.

Figs. 20 and 21, muscular fibre-cells from another artery. In fig. 20, the spirals are much
closer than in fig. 19; and in fig. 21, the spiral is quite close.

Figs. 22 and 23 represent some fibre-cells in arteries of extreme minuteness, and show the
section of the nucleus surrounded by that of the fibre-cell.

VOL. XXI. PART IV. alk

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XXXIV.—On a Dynamical Top, for exhibiting the phenomena of the motion of a
system of invariable form about a fixed point, mith some suggestions as to the
Earth’s motion. By J.C. Maxwe t, B.A., Professor of Natural Philosophy
in Marischal College, Aberdeen.

(Read 20th April 1857.)

To those who study the progress of exact science, the common spinning-top is
a symbol of the labours and the perplexities of men who had successfully threaded
the mazes of the planetary motions. The mathematicians of the last age, search-
ing through nature for problems worthy of their analysis, found in this toy of
their youth, ample occupation for their highest mathematical powers.

No illustration of astronomical precession can be devised more perfect than
that presented by a properly balanced top, but yet the motion of rotation has in-
tricacies far exceeding those of the theory of precession.

Accordingly, we find EvLer and D’ALEemBErt devoting their talent and their
patience to the establishment of the laws of the rotation of solid bodies. La-
grange has incorporated his own analysis of the problem with his general treat-
ment of mechanics, and since his time M. Pornsor has brought the subject under
the power of a more searching analysis than that of the calculus, in which ideas
take the place of symbols, and intelligible propositions supersede equations.

In the practical department of the subject, we must notice the rotatory machine
of BoHNENBERGER, and the nautical top of Trouacuton. In the first of these in-
struments we have the model of the Gyroscope, by which Foucautr has been
able to render visible the effects of the earth’s rotation. The beautiful experi-
ments by which Mr J. Exzior has made the ideas of precession so familiar to us
are performed with a top, similar in some respects to TrouGHToN’s, though not
borrowed from his.

The top which I have the honour to spin before the Society, differs from that
of Mr Ex.iot in having more adjustments, and in being designed to exhibit far
more complicated phenomena.

The arrangement of these adjustments, so as to produce the desired effects,
depends on the mathematical theory of rotation. The method of exhibiting the
motion of the axis of rotation, by means of a coloured disc, is essential to the
success of these adjustments. This optical contrivance for rendering visible the
nature of the rapid motion of the top, and the practical methods of applying the
theory of rotation to such an instrument as the one before us, are the grounds on
‘which I bring my instrument and experiments before the Society as my own.

I propose, therefore, in the first place, to give a brief outline of such parts of

VOL. XXI. PART Iv. 7M

560 PROFESSOR MAXWELL ON A DYNAMICAL TOP.

the theory of rotation as are necessary for the explanation of the phenomena of
the top.

I shall then describe the instrument with its adjustments, and the effect of
each, the mode of observing of the coloured disc when the top is in motion, and
the use of the top in illustrating the mathematical theory, with the method of
making the different experiments.

Lastly, I shall attempt to explain the nature of a possible variation in the
earth’s axis due to its figure. This variation, if it exists, must cause a periodic
inequality in the latitude of every place on the earth’s surface, going through its
period in about eleven months. The amount of variation must be very small,
but its character gives it importance, and the necessary observations are already
made, and only require reduction.

On the Theory of Rotation.

The theory of the rotation of a rigid system is strictly deduced from the
elementary laws of motion, but the complexity of the motion of the particles of
a body freely rotating renders the subject so intricate, that it has never been
thoroughly understood by any but the most expert mathematicians. Many who
have mastered the lunar theory have come to erroneous conclusions on this sub-
ject; and even Newvron has chosen to deduce the disturbance of the earth’s axis
from his theory of the motion of the nodes of a free orbit, rather than attack the
problem of the rotation of a solid body.

The method by which M. Pornsor has rendered the theory more manageable,
is by the liberal introduction of “appropriate ideas,” chiefly of a geometrical
character, most of which had been rendered familiar to mathematicians by the
writings of Monce, but which then first became illustrations of this branch of
dynamics. If any further progress is to be made in simplifying and arranging
the theory, it must be by the method which Pornsor has repeatedly pointed out
as the only one which can lead to a true knowledge of the subject,—that of pro-
ceeding from one distinct idea to another, instead of trusting to symbols and
equations.

An important contribution to our stock of appropriate ideas and methods has
lately been made by Mr R. B. Haywarp, in a paper, “ On a Direct Method of esti-
mating Velocities, Accelerations, and all similar quantities, with respect to axes,
moveable in any manner in Space.” (Z’rans. Cambridge Phil. Soc. vol. x. part i.)

* In this communication I intend to confine myself to that part of the subject
which the top is intended to illustrate, namely, the alteration of the position of
the axis in a body rotating freely about its centre of gravity. I shall, therefore,
deduce the theory as briefly as possible, from two considerations only,—the per-

* 7th May 1857.—The paragraphs marked thus have been rewritten since the paper was read.

PROFESSOR MAXWELL ON A DYNAMICAL TOP. 561

manence of the original angular momentum in direction and magnitude, and the
permanence of the original vis viva.

* The mathematical difficulties of the theory of rotation arise chiefly from the
want of geometrical illustrations and sensible images, by which we might fix the
results of analysis in our minds.

It is easy to understand the motion of a body revolving about a fixed axle.
Every point in the body describes a circle about the axis, and returns to its
original position after each complete revolution. But if the axle itself be in
motion, the paths of the different points of the body will no longer be circular or
re-entrant. Even the velocity of rotation about the axis requires a careful defi-
nition, and the proposition that, in all motion about a fixed point, there is always
one line of particles forming an instantaneous axis, is usually given in the form
of a very repulsive mass of calculation. Most of these difficulties may be got
rid of by devoting a little attention to the mechanics and geometry of the pro-
blem before entering on the discussion of the equations.

Mr Haywarbp, in his paper already referred to, has made great use of the
mechanical conception of Angular Momentum.

Derinition.— The Angular Momentum of a particle about an axis is measured
by the product of the mass of the particle, its velocity resolved in the normal plane,
and the perpendicular from the axis on the direction of motion.

* The angular momentum of any system about an axis is the algebraical sum
of the angular momenta of its parts.

As the rate of change of the linear momentum of a particle measures the
moving force which acts on it, so the rate of change of angular momentum mea-
sures the moment of that force about an axis.

All actions between the parts of a system, being pairs of equal and opposite
forces, produce equal and opposite changes in the angular momentum of those
parts. Hence the whole angular momentum of the system is not affected by
these actions and re-actions.

* When a system of invariable form revolves about an axis, the angular
velocity of every part is the same, and the angular momentum about the axis
is the product of the angular velocity and the moment of mertia about that
axis.

* It is only in particular cases, however, that the whole angular momentum
can be estimated in this way. In general, the axis of angular momentum differs
from the axis of rotation, so that there will be a residual angular momentum
about an axis perpendicular to that of rotation, unless that axis has one of three
positions, called the principal axes of the body.

By referring everything to these three axes, the theory is greatly simplified.
The moment of inertia about one of these axes is greater than that about any
other axis through the same point, and that about one of the others is a mini-

562 PROFESSOR MAXWELL ON A DYNAMICAL TOP.

mum. These two are at right angles, and the third axis is perpendicular to
their plan, and is called the mean axis.

* Let A, B, C be the moments of inertia about the principal axis through the
centre of gravity, taken in order of magnitude, and let w, w, w, be the angular
velocities about them, then the angular momentum will be Aw,, Bw, and Cw,.

Angular momentum may be compounded like forces or velocities, by the law of
the “ parallelogram,” and since these three are at right angles to each other, their
resultant is

V A?0,? + B?w,? + C?w,?=H ails te ‘ : (1)

and this must be constant, both in magnitude and direction in space, since no
external forces act on the body.

We shall call this axis of angular momentum the ¢nvariable axis. It is per-
pendicular to what has been called the invariable plane. Pornsor calls it the axis
of the couple of impulsion. The direction-cosines of this axis in the body are,

Since /, m, and vary during the motion, we need some additional condition
te determine the relation between them. We find this in the property of the vis-
viva of a system of invariable form in which there is no friction. The vis-viva of
such a system must be constant. We express this in the equation

Aw,? + Bw,? + Cw,?=V: : (2)

Substituting the values of w, w, w, in terms of /, m,

AB! oO] Le
Thet. 1, .. 05th we es Nee,
Y Gala oh rk aa
and this equation becomes
a? 17+? m?24+¢? rn? =e : ; ‘ , ‘ (8)

and the equation to the cone, described by the invariable axis within the body,
* (a? — €?)a?-+(b? — e?) y? + (c? —e?)2?=0 ; . : (4)

The intersections of this cone with planes perpendicular to the principal axes
are found by putting 2, y, or z, constant in this equation. By giving ¢ various
values, all the different paths of the pole of the invariable axis, corresponding to
different initial circumstances, may be traced.

* In the figures, I have supposed a?=100, 6°=107, and c?=110. ‘The first
figure represents a section of the various cones by a plane perpendicular to the
axis of w, which is that of greatest moment of inertia. These sections are ellipses
having their major axis parallel to the axis of 6. The value of ¢ corresponding
to each of these curves is indicated by figures beside the curve. The ellipticity

PROFESSOR MAXWELL ON A DYNAMICAL TOP. 563

increases with the size of the ellipse, so that the section corresponding to e?=107
would be two parallel straight lines (beyond the bounds of the figure), after which
the sections would be hyperbolas.

* The second figure represents the sections made by a plane, perpendicular to
the mean axis. They are all hyperbolas, except when ¢?=107, when the section
is two intersecting straight lines.

The third figure shows the sections perpendicular to the axis of least moment
of inertia. From ¢=110 to ¢=107 the sections are ellipses, ¢ =107 gives two
parallel straight lines, and beyond these the curves are hyperbolas.

* The fourth and fifth figures show the sections of the series of cones made
by a cube and a sphere respectively. The use of these figures is to exhibit the
connexion between the different curves described about the three principal axes
by the invariable axis during the motion of the body.

* We have next to compare the velocity of the invariable axis with respect to
the body, with that of the body itself round one of the principal axes. Since the
invariable axis is fixed in space, its motion relative to the body must be equal and
opposite to that of the portion of the body through which it passes. Now the
angular velocity of a portion of the body whose direction-cosines are /, m,n, about
the axis of 2 is

soe eat @, +-mW,+nW,)

Substituting the values of w,, w,, @,, in terms of /, m, n, and taking account of
equation (3), this expression becomes
(a?—)

a

H

Changing the sign and putting lao we have the angular velocity of the in-

variable axis about that of z.

Ww, e7 — a
1—/? a

always positive about the axis of greatest moment, negative about that of least
moment, and positive or negative about the mean axis according to the value
of @. The direction of the motion in every case is represented by the arrows in
the figures. The arrows on the outside of each figure indicate the direction of
rotation of the body.

* Tf we attend to the curve described by the pole of the invariable axis on the
sphere in fig. 5, we shall see that the areas described by that point, if projected
on the plane of y z, are swept out at the rate

SI)

'Z

VOL. XXI. PART IV.

564 PROFESSOR MAXWELL ON A DYNAMICAL TOP.

Now the axes of the projection of the spherical ellipse described by the pole are,
e— ae e? — gq?
= ne =

Dividing the area of this ellipse by the area described during one revolution

of the body, we find the number of revolutions of the body during the description
of the ellipse—

a?
Vea Vee

The projections of the spherical ellipses upon the plane of yz are all similar
ellipses, and described in the same number of revolutions; and in each ellipse so
projected, the area described in any time is proportional to the number of revo-
lutions of the body about the axis of 2, so that if we measure time by revolutions
of the body, the motion of the projection of the pole of the invariable axis is iden-
tical with that of a body acted on by an attractive central force varying directly
as the distance. In the case of the hyperbolas in the plane of the greatest and
least axis, this force must be supposed repulsive. The dots in the figures 1, 2, 3,
are intended to indicate roughly the progress made by the invariable axis during
each revolution of the body about the axis of z, y, and z respectively. It must
be remembered, that the rotation about these axes varies with their inclination to
the invariable axis, so that the angular velocity diminishes as the inclination
increases, and therefore the areas in the ellipses above mentioned are not de-
scribed with uniform velocity in absolute time, but are less rapidly swept out at
the extremities of the major axis than at those of the minor.

* When two of the axes have equal moments of inertia, or b = c, then the
angular velocity #, is constant, and the path of the invariable axis is circular,
the number of revolutions of the body during one circuit of the invariable axis,
being

az
6? —a?

The motion is in the same direction as that of rotation, or in the opposite
direction, according as the axis of wis that of greatest or of least moment of
inertia.

* Both in this case, and in that in which the three axes are unequal, the
motion of the invariable axis in the body may be rendered very slow by diminish-
ing the difference of the moments of inertia. The angular velocity of the axis
of a about the invariable axis in space is

e2 —q? 1
“1a?(1—P)
which is greater or less than w,, as ¢ is greater or less than a*, and, when these
quantities are nearly equal, is very nearly the same as %, itself. This quantity
indicates the rate of revolution of the axle of the top about its mean position,
and is very easily observed.

PROFESSOR MAXWELL ON A DYNAMICAL TOP. 965

* The ¢nstantancous axis is not so easily observed. It revolves round the in-
variable axis in the same time with the axis of 2, at a distance which is very
small in the case when a, 0, ¢, are nearly equal. From its rapid angular motion
in space, and its near coincidence with the invariable axis, there is no advantage
in studying its motion in the top.

* By making the moments of inertia very unequal, and in definite proportion
to each other, and by drawing a few strong lines as diameters of the disc, the
combination of motions will produce an appearance of epicycloids, which are the
result of the continued intersection of the successive positions of these lines, and
the cusps of the epicycloids lie in the curve in which the instantaneous axis
travels. Some of the figures produced in this way are very pleasing.

In order to illustrate the theory of rotation experimentally, we must have a
body balanced on its centre of gravity, and capable of having its principal axes
and moments of inertia altered in form and position within certain limits. We
must be able to make the axle of the instrument the greatest, least, or mean
principal axis, or to make it not a principal axis at all, and we must be able to
see the position of the invariable axis of rotation at any time. There must be ~
three adjustments to regulate the position of the centre of gravity, three for the
magnitudes of the moments of inertia, and three for the directions of the prin-
cipal axes, nine independent adjustments, which may be distributed as we please
among the screws of the instrument.

The form of the body of the instrument which I have found most suitable is
that of a bell, (Plate XVI. fig. 6.) C is a hollow cone of brass, Ris a heavy ring
cast in the same piece. Six screws, with heavy heads, 2, y, z, a’, y’, 2’, work
horizontally in the ring, and three similar screws, /, m,n, work vertically through
the ring at equal intervals. AS is the axle of the instrument, SS is a brass
screw working in the upper part of the cone C, and capable of being firmly
clamped by means of the nutc. B is a cylindrical brass bob, which may be
screwed up or down the axis, and fixed in its place by the nut 0.

The lower extremity of the axle is a fine steel point, finished without emery,
and afterwards hardened. It runs in a little agate cup set in the top of the pillar
P. Ifany emery had been embedded in the steel, the cup would soon be worn
out. The upper end of the axle has also a steel point by which it may be kept
steady while spinning.

When the instrument is in use, a coloured disc is attached to the upper end
of the axle.

It will be seen that there are eleven adjustments, nine screws in the brass
ring, the axle screwing in the cone, and the bob screwing on the axle. The ad-
vantage of the last two adjustments is, that by them large alterations can be
made, which are not possible by means of the small screws.

566 PROFESSOR MAXWELL ON A DYNAMICAL TOP.

The first thing to be done with the instrument is, to make the steel point at
the end of the axle coincide with the centre of gravity of the whole. This is done
roughly by screwing the axle to the right place nearly, and then balancing the
instrument on its point, and screwing the bob and the horizontal screws till the
instrument will remain balanced in any position in which it is placed.

When this adjustment is carefully made, the rotation of the top has no ten-
dency to shake the steel point in the agate cup, however irregular the motion may
appear to be.

The next thing to be done,.is to make one of the principal axes of the central
ellipsoid coincide with the axle of the top.

To effect this, we must begin by spinning the top gently about its axle, steady-
ing the upper part with the finger at first. If the axle is already a principal axis
the top will continue to revolve about its axle when the finger is removed. If it
is not, we observe that the top begins to spin about some other axis, and the axle
moves away from the centre of motion and then back to it again, and so on, al-
ternately widening its circles and contracting them.

It is impossible to observe this motion successfully, without the aid of the
coloured disc placed near the upper end of the axis. This disc is divided into
sectors, and strongly coloured, so that each sector may be recognised by its colour
when in rapid motion. If the axis about which the top is really revolving, falls
within this disc, its position may be ascertained by the colour of the spot at the
centre of motion. If the central spot appears red, we know that the invariable
axis at that instant passes through the red part of the disc.

In this way we can trace the motion of the invariable axis in the revolving
body, and we find that the path which it describes upon the disc may be acircle,
an ellipse, an hyperbola, or a straight line, according to the arrangement of the
instrument.

In the case in which the invariable axis coincides at first with the axle of the
top, and returns to it after separating from it for a time, its true path isa
circle or an ellipse having the axle in its circumference. The true principal axis
is at the centre of the closed curve. It must be made to coincide with the axle
by adjusting the vertical screws /, m, n.

Suppose that the colour of the centre of motion, when farthest from the axle,
indicated that the axis of rotation passed through the sector L, then the principal
axis must also lie in that sector at half the distance from the axle.

If this principal axis be that of greatest moment of inertia, we must raise the
screw J in order to bring it nearer the axle A. If it be the axis of least moment
we must ower the screw /. In this way we may make the principal axis coincide
with the axle. Let us suppose that the principal axis is that of greatest moment
of inertia, and that we have made it coincide with the axle of the instrument.
Let us also suppose that the moments of inertia about the other axes are equal,

PLATE XVI Royal Soe Trans Vol KET

\S
i

S

NN

SS

Ws

NN

SS
mnt

iil

W.&AKJohnston, Edinburgh.

-

ej }

oye

PROFESSOR MAXWELL ON A DYNAMICAL TOP. 567

and very little less than that about the axle. Let the top be spun about the axle
and then receive a disturbance which causes it to spin about some other axis.
The instantaneous axis will not remain at rest either in space or in the body.
In space it will describe aright cone, completing a revolution in somewhat less
than the time of revolution of the top. In the body it will describe another cone
of larger angle in a period which is longer as the difference of axes of the body is
smaller. The invariable axis will be fixed in space, and describe a cone in the body.

The relation of the different motions may be understood from the following
illustration. Take a hoop and make it revolve about a stick which remains at
rest and touches the inside of the hoop. The section of the stick represents the
path of the instantaneous axis in space, the hoop that of the same axis in the
body, and the axis of the stick the invariable axis. The point of contact repre-
sents the pole of the instantaneous axis itself, travelling many times round the
stick before it gets once round the hoop. It is easy to see that the direction in
which the instantaneous axis travels round the hoop, is in this case the same as
that in which the hoop moves round the stick, so that if the top be spinning in
the direction L, M, N, the colours will appear in the same order.

By screwing the bob B up the axle, the difference of the axes of inertia may
be diminished, and the time of a complete revolution of the invariable axis in the
body increased. By observing the number of revolutions of the top in a complete
cycle of colours of the invariable axis, we may determine the ratio of the moments
of inertia.

By screwing the bob up farther, we may make the axle the principal axis of
least moment of inertia.

The motion of the instantaneous axis will then be that of the point of contact
of the stick with the outside of the hoop rolling on it. The order of colours will
be N, M, L, if the top be spinning in the direction L, M, N, and the more the bob
_ is screwed up, the more rapidly will the colours change, till it ceases to be possible
to make the observations correctly.

In calculating the dimensions of the parts of the instrument, it is necessary to
provide for the exhibition of the instrument with its axle either the greatest or
the least axis of inertia. The dimensions and weights of the parts of the top
which I have found most suitable, are given in a note at the end of this paper.

Now let us make the axes of inertia in the plane of the ring unequal. . We
may do this by screwing the balance screws « and w' farther from the axle with-
out altering the centre of gravity.

Let us suppose the bob B screwed up so as to make the axle the axis of least
inertia. Then the mean axis is parallel to vz', and the greatest isat right angles
to x«'in the horizontal plane. The path of the invariable axis on the disc is
no longer a circle but an ellipse, concentric with the disc, and having its major
axis parallel to the mean axis va!.

VOL. XXI. PART Iv. 70

568 PROFESSOR MAXWELL ON A DYNAMICAL TOP.

The smaller the difference between the moment of inertia about the axle and
about the mean axis, the more eccentric the ellipse will be; and if, by screwing
the bob down, the axle be made the mean axis, the path of the invariable axis
will be no longer a closed curve, but an hyperbola, so that it will depart alto-
gether from the neighbourhood of the axle. When the top is in this condition it
must be spun gently, for it is very difficult to manage it when its motion gets
more and more eccentric.

When the bob is screwed still farther down, the axle becomes the axis of
greatest inertia, and va’ the least. The major axis of the ellipse described by
the invariable axis will now be perpendicular to va’, and the farther the bob
is screwed down, the eccentricity of the ellipse will diminish, and the velocity
with which it is described will increase.

I have now described all the phenomena presented by a body revolving freely
on its centre of gravity. If we wish to trace the motion of the invariable axis by
means of the coloured sectors, we must make its motion very slow compared with
that of the top. It is necessary, therefore, to make the moments of inertia about
the principal axes very nearly equal, and in this case a very small change in the
position of any part of the top will greatly derange the position of the principal
axis. So that when the top is well adjusted, a single turn of one of the screws
of the ring is sufficient to make the axle no longer a principal axis, and to set
the true axis at a considerable inclination to the axle of the top.

All the adjustments must therefore be most carefully arranged, or we may
have the whole apparatus deranged by some eccentricity of spinning. The method
of making the principal axis coincide with the axle must be studied and practised,
or the first attempt at spinning rapidly may end in the destruction of the top, if
not of the table on which it is spun. }

On the Earth's Motion.

We must remember that these motions of a body about its centre of gravity,
are not illustrations of the theory of the precession of the Equinoxes. Precession
can be illustrated by the apparatus, but we must arrange it so that the force of
gravity acts the part of the attraction of the sun and moon in producing a force
tending to alter the axis of rotation. This is easily done by bringing the centre
of gravity of the whole a little below the point on which it spins. The theory of
such motions is far more easily comprehended than that which we have been
investigating. ;

But the earth is a body whose principal axes are unequal, and from the phe-
nomena of precession we can determine the ratio of the polar and equatorial axes
of the “central ellipsoid ;” and supposing the earth to have been set in motion
about any axis except the principal axis, or to have had its original axis disturbed

PROFESSOR MAXWELL ON A DYNAMICAL TOP. 569

in any way, its subsequent motion would be that of the top when the bob isa little
below the critical position.

The axis of angular momentum would have an invariable position in space,
and would travel with respect to the earth round the axis of figure with a velo-

city=0 “—* where is the sidereal angular velocity of the earth. The apparent

pole of the earth would travel (with respect to the earth) from west to east round
the true pole, completing its circuit in ay sidereal days, which appears to be

about 325-6 solar days.

The instantaneous axis would revolve about this axis in space in abouta day,
and would always be in a plane with the true axis of the earth and the axis of
angular momentum. The effect of such a motion on the apparent position of a
star would be, that its zenith distance would be increased and diminished during
a period of 325°6 days. This alteration of zenith distance is the same above and
below the pole, so that the polar distance of the star is unaltered. In fact the
method of finding the pole of the heavens by observations of stars, gives the pole
of the invariable axis, which is altered only by external forces, such as those of
the sun and moon.

There is therefore no change in the apparent polar distance of stars due to this
cause. It is the latitude which varies. The magnitude of this variation cannot
be determined by theory. The periodic time of the variation may be found ap-
proximately from the known dynamical properties of the earth. The epoch of
maximum latitude cannot be found except by observation, but it must be later
in proportion to the east longitude of the observatory. é

In order to determine the existence of such a variation of latitude, I have
examined the observations of Polaris with the Greenwich Transit Circle in the
years 1851-2,3-4. The observations of the upper transit during each month were
collected, and the mean of each month found. The same was done for the lower
transits. The difference of zenith distance of upper and lower transit is twice
the polar distance of Polaris, and half the sum gives the co-latitude of Greenwich.

In this way I found the apparent co-latitude of Greenwich for each month of the
four years specified.

There appeared a very slight indication of a maximum belonging to the set of
months,

March, 51. Feb. 52. Dec. 52. Nov. 53. Sept. 54.

This result, however, is to be regarded as very doubtful, as there did not ap-
pear to be evidence for any variation exceeding half a second of space, and more
observations would be required to establish the existence of so small a variation
at all. |

I therefore conclude that the earth has been for a long time revolving about

570 PROFESSOR MAXWELL ON A DYNAMICAL TOP.

an axis very near to the axis of figure, if not coinciding with it. The cause of this
near coincidence is either the original softness of the earth, or the present fluidity
of its interior. The axes of the earth are so nearly equal, that a considerable
elevation of a tract of country might produce a deviation of the principal axis
within the limits of observation, and the only cause which would restore the uni-
form motion, would be the action of a fluid which would gradually diminish the
oscillations of latitude. The permanence of latitude essentially depends on the
inequality of the earth’s axes, for if they had been all equal, any alteration of the
crust of the earth would have produced new principal axes, and the axis of rota-
tion would travel about those axes, altering the latitudes of all places, and yet
not in the least altering the position of the axis of rotation among the stars.

Perhaps by amore extensive search and analysis of the observations of different
observatories, the nature of the periodic variation of latitude, if it exist, may be
determined. I am not aware of any calculations having been made to prove its
non-existence, although, on dynamical grounds, we have every reason to look for
some very small variation having the periodic time of 325-6 days nearly, a period
which is clearly distinguished from any other astronomical cycle, and therefore
easily recognised.

Norte.
Dimensions and Weights of the parts of the Dynamical Top.

I. Body of the top—
Mean diameter of ring, 4 inches.
Section of ring, 4 inch square.
The conical portion rises from the upper and inner edge of the ring, a height
of 13 inches from the base.

The aanle body of the top weighs J 11lb.7 oz.
Each of the nine adjusting screws has jie screw 1 neh long, and fee screw
and head together weigh 1 ounce. The whole weigh : : act
II. Axle, &c.—

Length of axle 5 inches, of which 3 inch at the bottom is occupied by the steel
point, 35 inches are brass with a good screw turned on it, and the re-
maining inch is of steel, with a abaeP point at the toms The whole

weighs : 13 ,,
The bob B has a diameter of 1:4 inches, and : a thickness of “4, It WOERS | : 23 ,,
The nuts 6 and 2 for clamping the bob and the es of the ne on the axle,

each weigh 4 oz. 4 5 Os

Weight of whole top 2 lb. 54 oz.

The best arrangement, for general observations, is to have the disc of card divided into four
quadrants, coloured with vermilion, chrome yellow, emerald green, and ultramarine. These are
bright colours, and, if the vermilion is good, they combine into a grayish tint when the revolution
is about the axle, and burst into brilliant colours when the axis is disturbed. It is useful to have
some concentric circles, drawn with ink, over the colours, and about 12 radii drawn in strong pencil
lines. It is easy to distinguish the ink from the pencil lines, as they cross the invariable axis, by
their want of lustre. In this way, the path of the invariable axis may be identified with great accu-
racy, and compared with theory.

(571)

XXXV.—On the Products of the Destructive Distillation of Animal Matters. Part IV.
By Tuomas ANDERSON, Professor of Chemistry, University of Glasgow.

(Read 20th April 1857.)

Owing to the great length of time over which the investigation of the pro-
ducts of the destructive distillation of animal substances has stretched, and
various circumstances which it is unnecessary to detail, the inquiry has been
pursued in a somewhat fragmentary manner, and with less continuity than
might have been desired. The difficulties attending many of the experiments,
and the occasional exhaustion of materials prepared by laborious processes, ex-
tending in many instances over considerable periods, have occasioned long inter-
vals in the regular course of the inquiry which it became necessary to occupy
with the examination of such matters as could be taken up at the moment. In
this way a number of facts required to complete the history of the bases already
described have gradually been accumulated, some of the products of their decom-
position examined, and the pyrrol so frequently adverted to in the previous
parts of this paper has been subjected to a full investigation. The details of
these experiments form the subject of the present communication.

It has been already shown that the whole series of the alcohol bases, from
methylamine to butylamine, can be obtained from bone oil, and the probable
existence of amylamine in the portion boiling, about 200°, has been pointed out.
The quantity of base obtained at that temperature is by no means large; but
enough was collected not only to prove the existence of amylamine, but to sub-
stantiate the fact that it was unquestionably that base, and not one of its
isomeres. After sufficient rectification it gave, with bichloride of platinum, an
extremely beautiful platinum salt, which, when the fluid was sufficiently concen-
trated, deposited itself after some time in fine golden yellow scales, very soluble in
water. The mother liquor, on evaporation, yielded another crop, agreeing with
the first in properties and composition. A platinum determination of each gave
the subjoined results :—

I. 5:39 grains of the platinum salt gave 1:815 grains of platinum.
II. 2:99 grains gave 1:010 gers. platinum,

Experiment. Calculation,
ie Il.

Carbon, : ; ; ae ee 20°46 CG 60
Hydrogen, . ; : od ad 4:77 Ee 14
Nitrogen, . : : er. “af 477 N 14
Chlorine, : ; one EM 36°34 Cl, 106°5
Platinum, . : : 33:67 33°77 33°66 Lay 98-7

100:00 293°2

VOL. XXI. PART Iv. 7P

572 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

When the base was treated with iodide of amyle in a sealed tube, it rapidly
dissolved; and, on cooling, the fluid became filled with fine crystalline plates.
These crystals, when treated with potash, evolved a smell quite distinct from
that of amylamine, much more pleasant, and devoid of that putrid odour which
distinguishes the whole of the alcohol amide bases. When a quantity of the iodide
was introduced into a retort, with an excess of potash, and distilled into a mo-
derately dilute solution of hydrochloric acid, a salt immediately deposited itself
as a crystalline powder of sparing solubility, and possessing all the characters of
the hydrochlorate of diamylamine. Analysis gave the following results :—

14-505 grains of carbonic acid and
7°280 grains water.
8-240 grains dried at 212° gave
{ 6°165 grains of chloride of silver.

6-400 grains dried at 212° gave

Experiment. Calculation.
EE ha Fee
Carbon, : : ; 61-80 62°10 C5 120-
Hydrogen, ; : ; 12°63 12°40 1 24°
Nitrogen, ; : : bast 7:16 N 14:
Chlorine, : > : 18-50 18:34 Cl 35°5
100-00 193-5

These experiments prove incontestably that the base is amylamine, and they
afford an indirect refutation of the opinion expressed by some chemists, that the
substance described in a previous part of this paper as propylamine, might pos-
sibly be trimethylamine. The occurrence of the whole series of the alcohol bases,
with their proper boiling points, as well as many facts observed during the inves-
tigation, had fully convinced me of the accuracy of my original opinion; but the
experiments now detailed, showing that one of them is really an amide base, may
be taken as affording the strongest possible evidence that the others are similarly
constituted.

Various attempts have been made to ascertain whether any of the higher
members of the alcohol series of bases, and particularly caprylamine, exist in
bone oil, but without success. Some difficulty attends the examination, because
the boiling points of these substances do not differ very greatly from those of the
different members of the pyridine series, and a small quantity existing along with
the latter might easily escape detection, but a careful examination of the first por-
tions passing over during the distillation of pyridine, and which ought to contain
any caprylamine, has satisfied me that it is not present. Taking into account
the great difference in the quantity of hydrogen in these two bases; the for-
mer containing 6°3, and the latter 14:9 per cent. of that element, we should
anticipate, that in the analysis of the first portions of pyridine, the hydrogen
would be in excess if it contained caprylamine, and farther, as the bases of
the alcohol series are stronger than those of the pyridine series, it would follow

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 573

that, if a mixture of two such bases were partially saturated by an acid, the salt
produced should consist chiefly of the stronger base, and consequently should
give a large excess of hydrogen. Salts prepared in this way gave the exact
results required for pyridine, as will be seen in a subsequent page.

Pyridine and its Compounds.

In the second part of this paper a very cursory account was given of pyridine
and its platinum salt, at a time when I had obtained this beautiful base in com-
paratively small quantity. Subsequent experiments have afforded me a much
larger supply, and rendered it possible to submit it and its compounds to a more
minute investigation. It is a transparent and colourless oil, with a powerful
pungent smell, soluble in water in all proportions, and obtained absolutely dry
only with some difficulty. It boils at 242°, and its specific gravity at 32° F. is
09858. It precipitates the salts of zinc, iron, manganese, and alumina in the
cold, nickel only on the application of heat, and the precipitate dissolves in
excess. Copper gives a pale blue precipitate, soluble in excess of base with a
deep blue colour, not distinguishable from that produced by ammonia. It has a.
remarkable tendency to form double salts, most of which are highly crystallizable,
and retain the metallic oxide in a state in which it cannot be precipitated by
excess of pyridine. An analysis gave—

8-830 ... carbonic acid, and

3°175 grains of carefully dried pyridine gave
1:950 ... . water.

Calculation.

Carbon, ‘ ; : . 75°84 75:94 Ce 60
Hydrogen, . : " ; 6°82 6°33 H, 5
Nitrogen, . : : : son 17°73 N 14

100-00 79

The density of the vapour of pyridine determined by Dumas’s method, gave—

i It.
Temperature of the air, . ‘ ; 14° cent. 15° ¢.

" vapour, . fe LOA hy, 143°
Excess of weight of the balloon, . 0°3088 grammes. 0:4060 gr.
Capacity of the balloon, a, : 305 c.¢. 324 ¢. ¢.
Barometer, . j ; ; j 765 m. m. 752 m. m.
Residual air, 5 i i ; 14 ce, ss
Density of vapour, . é ‘ 2912 2°920

The formula C,, H, N requires

10 vol. carbon vapour = 0°8290 x 10 = 8:2900
10°... Hydrogen. = 00692" 10'="0-6920
2 .:. nitrogen ... = O97I3x 2 = 1:'9426
10 9246

=2°734

574 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

These experimental results are somewhat in excess of the theoretical density ;
but this is in all probability due to the presence of a small quantity of picoline,
which, from the nature of the experiment, must necessarily remain in the balloon,
and tend to produce an appreciable error in the density, even when its quantity
is far too minute to be distinguished by an ordinary analysis. The specimen of
pyridine used in these experiments had been purified with great care, and its
platinum salt gave results corresponding completely with theory.

Salts of Pyridine.

Hydrochlorate of Pyridine.—W hen hydrochloric acid is saturated with pyridine,
and the solution evaporated on the water bath, the salt remains in the form of a
thick syrup, so long as it is warm, but on cooling, crystals slowly make their
appearance, and gradually shoot through the fluid, which is eventually converted
into a hard radiated mass. The salt deliquesces when exposed to moist air, and
sublimes unchanged at a high temperature. It is very soluble in alcohol, but less
so than in water. It is insoluble in ether.

Hydriodate of Pyridine.—This salt crystallizes in tabular crystals, readily
soluble both in water and alcohol, but not deliquescent. An analysis of the salt
in an impure state will be afterwards given.

Hydrobromate of Pyridine.—A deliquescent salt, obtained on evaporation as
a mass of acicular crystals.

Nitrate of Pyridine.—This salt is easily obtained by mixing nitric acid and
the base. Ifthe acid be concentrated, and the base dry, or nearly so, much heat
is produced, and the mixture rapidly solidifies into a mass of short needles, which,
when expressed between folds of blotting-paper, closely resembles loaf-sugar.
The salt is purified by solution in hot water, or better in boiling spirit. On cooling,
it is deposited from the latter solution in fine needles, which can easily be obtained
an inch long, even when operating on a very small scale. Sometimes it appears
in short thick prisms. It is not deliquescent, but is extremely soluble in water,
less so in alcohol, and not at all in ether. When heated in a retort it melts; and if
the temperature be raised very gradually it sublimes as a white woolly mass; but,
if briskly heated, it distils in the form of a thick oily fluid, which solidifies in the
neck of the retort to a mass of acicular crystals. Ifthe heat be carefully regu-
lated it sublimes without undergoing the least change, but if rapidly distilled,
a small quantity of red fumes are occasionally seen. Heated on a platinum knife
it catches fire and burns with great brilliancy, and a rapidity almost approaching
to deflagration. Analyses made on different preparations gave the following
results :—

9-238 ... carbonic acid and

5:954 grains of nitrate dried at 212° gave
I
2:358 ... water.

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 575

9°377 ... carbonic acid and

6:036 grains of nitrate dried in vacuo gave
II
2°324 sap ay tUen:

6:889 ... carbonic acid and

4'455 grains obtained from the mother liquor of the previous crop gave
III.
1:738 ... water.

7-118 grains of nitrate dried at 212° gave
IV 11:009 ... carbonic acid and

2-767 ... water.

Experiment. Calculation.
SS ne nS en aa rE TT
I. II. III. IV.
Carbon, 42°31 42:37 42:17 42°18 429.25 Cio 60
Hydrogen, 4°40 4°28 4°32 4:31 4:22 H, 6
Nitrogen, nie ae fe: 19-73 ING 28
Oxygen, 33°80 O; 48
100:00 142

These results correspond completely with the formula C,,H,N HO NO..

Bisulphate of Pyridine.—When sulphuric acid is supersaturated with pyridine,
and evaporated in the water bath, a crystalline mass is left which is deliquescent,
and soluble in all proportions in water and alcohol, but insoluble in ether. Its re-
action is highly acid, and analysis showed it to be a bisulphate.

21:012 grains bisulphate of pyridine, gave
27:867 .., sulphate of baryta=45-50 per cent. of sulphuric acid,

The formula C,,H,N 2HO SO, requires 45°19.

Double Salts of Pyridine.

The platinochloride of pyridine has been already described in the second part
of this investigation.

Aurochloride of Pyridine—tThis salt is immediately thrown down as a fine
lemon-yellow crystalline powder when chloride of gold is added to a solution of
hydrochlorate of pyridine. It dissolves readily in hot water, and is deposited, on
cooling, in fine yellow needles, little soluble in cold water, and insoluble in al-

cohol. Analysis gave—

46°40 ... carbonic acid and

8:525 grains aurochloride gave
1-450 ... -water.

I 7°350 grains aurochloride gave
* 13-440... gold.

Il 5:480 grains aurochloride gave
2565 ... gold.

“J

VOL. XXI. PART IV.

576 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

Experiment, Calculation.
Te 2
Carbon, F ; . 14:84 ae 14:32° Cro 60
Hydrogen, . : P 1:89 or 1:43 i. 6
Nitrogen, . . 5 255 ae 3°34 N 14
Chlorine, : , see acy 33°90 Cl, 142
Gold, ; : . 46°80 46:62 47-01 Au 197
100-00 419

Corresponding with the formula C,,H,N HCl Au Cl,.

When pyridine is added to a moderately dilute solution of sulphate of zine
in considerable excess, oxide of zinc is precipitated. And if a quantity of hydro-
chloric acid insufficient to neutralize the pyridine be then added, the fluid instantly
becomes clear ; but if it be stirred briskly, it rapidly fills with an abundant crys-
talline precipitate of a double salt. The salt dissolves with facility in boiling
water, and is deposited, on cooling, in long, brilliant needles. Sulphate of cop-
per, when treated in a similar manner, gives a pale greenish-blue precipitate, so-
luble in boiling water, from which it crystallizes in fine bluish needles. The salts
of manganese and nickel, and protoxide of iron, appear also to form double salts,
but they are very soluble, and have not been particularly examined.

Products of the Decomposition of Pyridine.

Pyridine, like all its homologues, is an exceedingly stable base, and resists the
action of oxidising agents. It may be boiled with the most concentrated nitric
acid, or with chromic acid, without undergoing decomposition; and treatment
with the former acid affords an invaluable means of freeing those bases from any
empyreumatic matters with which they may be mixed.

Action of Chlorine on Pyridine.—The action of chlorine on pyridine depends
upon the mode in which that agent is employed. When a current of the gas is
passed through an aqueous solution of the base it is rapidly absorbed, the fluid
acquires a dark brown colour, and evolves a peculiar pungent odour; and on
the addition of potash, the smell of unchanged pyridine becomes apparent, while
a quantity of a dark brown resinous matter is separated. But if an excess of
pyridine be thrown into a large bottle of dry chlorine, and distributed over the
sides as rapidly as possible, in order to prevent rise of temperature, it remains
perfectly colourless, and is converted into a mass of radiated crystals. On the
addition of water the crystals dissolve, leaving a quantity of a snow-white amor-
phous powder, and hydrochlorate of pyridine is found in the solution. The
white powder has a faint smell, not unlike that of bleaching powder. It is inso-
luble in water, but dissolves in alcohol, and is precipitated again in white flocks
on the addition of water. When boiled for some time with water it softens, but

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS, 577
does not thoroughly melt, and at the same time exhales a peculiar irritating vapour,
due, apparently, to partial decomposition. It is insoluble in hydrochloric acid ;
strong nitric acid dissolves it, and the solution on boiling gives off red fumes; but
on the addition of water the original substance is deposited apparently unchanged.
Potash colours it brown, and on boiling dissolves it, giving a dark brown solution,
from which acids precipitate brown flocks. Ammonia, and even carbonate of
ammonia, produce a similar decomposition. When heated, it swells up, giving off
a pungent smell], and leaving a bulky charcoal. This substance has not been ana-
lysed, but the corresponding product of the decomposition of picoline has been
examined, and there can be no doubt that the two substances are of analogous
constitution. I shall defer any observations on this point until I come to treat of
the picoline compound. :

Action of Bromine on Pyridine—When bromine water is gradually added to a
solution of pyridine, the fluid becomes muddy, and as the quantity of bromine
increases, an abundant precipitate appears, and collects at the bottom of the ves-
sel in the form of a reddish mass of a more or less resinous appearance. This
substance is insoluble in water, but soluble in alcohol and ether. When boiled
with water it melts and emits a pungent and irritating odour, resembling that of
bromine. Hydrochloric acid decomposes it, dissolving pyridine, and liberating
bromine, which collects at the bottom of the fluid. Potash likewise decomposes
it, evolving pyridine, and combining with bromine. These characters lead to the
conclusion that the substance is a direct compound of pyridine, with in all proba-
bility, several equivalents of bromine; but its properties were not so definite
as to induce me to prepare it on a scale sufficiently large for a detailed exami-
nation and analysis. When dry pyridine is thrown into dry bromine vapour, it
immediately solidifies into a crystalline mass, which dissolves in water, with
the exception of a small quantity of a brownish flocky matter, probably analogous
to the compound produced by similar treatment with chlorine. The solution in
water becomes dark-coloured on evaporation, and yields a syrup which solidifies,
on standing, into a mass of minute crystals of hydrobromate of pyridine.

Action of Iodine on Pyridine.—When a mixture of pyridine and tincture of
iodine is evaporated to dryness on the water-bath, a dark brown mass is left,
which dissolves partially in water, leaving a quantity of brown crystals, too small
in amount to admit of examination, and which are very easily decomposed.
They appear to be a product similar to the iodine compounds of the fixed bases.
The watery solution contains a quantity of a brown matter, removable by animal
charcoal, and the fluid, on evaporation, yielded crystals which analysis proved to
be the hydriodate of pyridine, although not quite pure.

{ 5-774 grains dried at 212° gave
| 7673 ... iodide of silver,

578 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

Experiment. Calculation.
Carbon, , : : atte 29-01 Cio 60
Hydrogen, . : . eye 2:90 H, 6
Nitrogen, . z : ae 6°74 N 14
Todine, § : : 62°43 61°35 I 127
100-00 207

Corresponding with the formula C,,H,.N HI.

Picoline and its Compounds.

The compounds of picoline have already been pretty fully described in my
original paper on that base, but the possession of a larger quantity has induced
me to examine more in detail some of the products of its decomposition, and to
determine with greater exactitude certain of its physical properties. In the
paper just referred to I fixed its boiling point at 272°; but an experiment made
on a larger scale has convinced me that this is too low, and that when quite
pure it boils at 275°. The specific gravity at 32° is 0:9613. The density of its
vapour was determined by Dumas’s method with the following results :—

Temperature of the air, ° A . 13° cent.

re vapour, - “ : ; TGG ast
Excess of weight of the balloon, . : . 03490 gramme.
Capacity of do., : ; : . : 288 cc.
Barometer, : . i ; ; 762 m. m.
Residual air, j : 4 : ‘ 22 ‘edie,
Specific gravity of vapour, ‘ . ‘ : 3°29

The formula C,, H, N requires—

12 vol. carbon vapour= 0°8290 x 12=9-9480

14 ... hydrogen ... =0°0492 x 14=0°9685
2... nitrogen ... =O'9713x 2=—1:9626
12-8591

4

Nitrate of Picoline—This salt has been already described as a deliquescent
crystalline mass, but I have now succeeded in obtaining it in prismatic crystals
of considerable size, which are formed when a quantity of the dry salt, covered
with a saturated solution, is left for some weeks in a closely-stoppered bottle.
At the end of that time the salt has been converted into a small number of four-
sided prisms terminated by dihedral summits. Analysis gave—

8:580 .-- carbonic acid and

5°080 grains dried at 212° gave
2°395 --- water.

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 579

Experiment. Calculation.
Carbon, . 46:06 “46-15 oh 72
Hydrogen, . : : 5:23 5:12 Hi, 8
Nitrogen, . : ; ret 17:96 NG 28
Oxygen, : : : ae 30°77 OF 48
100-00 156

And its formula is C,,H,N HO NO,.

Products of the Decomposition of Picoline.

Action of Chlorine on Picoline.—The action of a current of chlorine on pico-
line, both dry and dissolved in water, has been already described, and the results
were not such as to induce further experiments in this way. But when an excess
of picoline is projected into dry chlorine gas, it is rapidly converted into a more
or less distinctly crystallized mass, which, when treated with water, leaves a
quantity of an amorphous powder of dazzling whiteness. The properties of this
substance are so like those of the corresponding pyridine compound, that the same
words would almost serve to describe it. Itis insoluble in water; but alcohol dis-
solves it easily, and the solution, when boiled, undergoes decomposition ; an ethe-
rial odour, not unlike that of hydrochloric ether, and probably due to the forma-
tion of that substance, is first produced, and that is followed by a pungent vapour.
It is insoluble in the dilute acids, but soluble in concentrated nitric acid. Potash
decomposes it in the cold, and more rapidly if heated. Heated on platinum, it
gives off a very pungent vapour and leaves a bulky charcoal. It is decomposed
when heated in the water bath. The portion used for analysis is dried in vacuo.
The results were,—

6°170 ... carbonic acid and

5:550 grains dried in vacuo gave
1-100) ....., water,

Boe grains burnt with lime gave

9°265 ... chloride of silver.
Experiment. Calculation.
Carbon, } : A 30°32 30°9° Cio 72
Hydrogen, . : ; 2°20 2°14 : 5
Nitrogen, 5 : oo 5:02 N 14
Chlorine, . 3 S 61:54 60-94 Cl, 142
233

This corresponds very closely with the formula

oF ct} H Cl.

or that of the hydrochlorate of a base produced by the substitution of three
VOL. XXI. PART IV. TR

580 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

equivalents of chlorine for three of hydrogen in picoline, and which would be
called trichloropicoline. This view derives confirmation, from the fact, that
when exposed to 212°, the substance loses an equivalent of hydrochloric acid, as
shown by the subjoined experiment.

2°815 grains heated to 212° gave
5960 ... chloride of silver.

This corresponds to 52°35 per cent. of chlorine, while the formula C,, ie } N re-
3

quires 54:2. Although this is only a very distant approximation to the theore-
tical number, the discrepancy is not greater than might be expected when the
properties of the substance, and the fact that it is coloured brown in the water
bath, are taken into account.

Action of Sodium on Prcoline.

When sodium is thrown into picoline in the cold, it remains unchanged, and
preserves its metallic lustre; but if the picoline be heated to its boiling point, an
action begins to manifest itself, brown streaks are seen to appear on the surface
of the sodium, and after continued boiling, the whole fluid becomes dark brown,
and at length nearly black and viscid. In order to examine this change more
minutely, picoline was introduced into a Florence flask, with a quantity of sodium,
which varied in different experiments from a fourth to an eighth of its weight;
and a long tube being fixed into the mouth of the flask, it was heated in the oil
bath in such a manner that the picoline cohobated freely. The action requires
some days for its completion, and at the end of that time the contents of the flask
are converted into a dark brown hard resinous mass, containing lumps of un-
changed sodium. The resinous matter contained sodium in some form of com-
bination which could not be determined ; the properties of the substance not being
such as to induce an extended examination. It burnt with a smoky flame,
leaving soda; and, when exposed to the air showed a tendency to deliquesce, and
became sticky on the surface. The pieces of sodium having been carefully re-
moved, the resinous matter was thrown into water, and on standing it was slowly
converted into a thick viscid and very dark-coloured oil, much heavier than
water, while soda was found in the solution. The oil smelt more or less dis-
tinctly of picoline, according to the length of time during which the action had
been carried on. After having been carefully washed, so as to remove the soda,
and then distilled with water, picoline passed over, and there was left behind a
thick oily base, requiring a very high temperature for its distillation, and to which,
for reasons to be afterwards explained, I give the name of parapicoline.

Parapicoline-—In the preparation of this base it was found not to be advan-
tageous to push the action of sodium to the extreme; and the cohobation was

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 581

generally stopped at the end of the second day, when a considerable quantity of
the picoline still remained unchanged, and the contents of the flask had acquired
the consistence of treacle. The flask was then broken, the sodium removed as
completely as possible, and the whole, along with the pieces of broken glass, to
which a considerable quantity of thick matter adhered, was thrown into water.
When the oil had collected at the bottom, which generally required some hours,
the pieces of glass were removed, the supernatant fluid decanted, and the oily
base washed with water, so as to remove the soda and the greater portion of the
unchanged picoline. Occasionally a somewhat different process was adopted;
the cohobating tube being replaced by another bent at right angles, and the heat
continued, so as to distil off and recover the dry picoline; but this was found
less convenient, as the increased viscidity of the contents of the flask rendered its
after-treatment more troublesome. The well-washed oil was introduced into a
small retort, and heat applied. At first a watery fluid containing picoline came
over, then dry picoline appeared, and subsequently an oil insoluble in water,
began to distil; while a thermometer, placed in the tubulature of the retort, rose at
first very rapidly, afterwards more slowly, until, towards the end of the distilla-
tion, the temperature reached a point considerably beyond the range of the ther- -
mometer. Some crystals of carbonate of ammonia made their appearance in the
neck of the retort ; traces of pyrrol could be distinguished, and a quantity of
charcoal was left. ‘These experiments rendered it sufficiently obvious that the
new base possessed a boiling point so high, and so near its point of decomposition
as to render necessary the utmost precautions for its purification. The first por-
tion of the distillate which contained unchanged picoline was therefore rejected,
and the remainder was heated in a retort immersed in the oil-bath to the boil-
ing point of picoline, while a current of dry hydrogen was passed through it.
At first a small quantity of picoline and some crystals of carbonate of ammonia
made their appearance; and when these ceased to increase, the temperature of
the bath was raised until it reached 380°, when the receiver was changed, and
the heat maintained as steadily as possible between that point and 400°, the
current of hydrogen being continued all the time. The base was thus made to
evaporate at a temperature considerably under its boiling point, and was obtained
ina much more satisfactory state, but even then it was not absolutely pure, as
it still gave faint indications of pyrrol, although the quantity must have been
excessively small; and though wholly soluble in acids, the solution retained a
distinctly empyreumatic smell. The small scale on which it was necessary to
experiment rendered it impossible to adopt any very efficient means of removing
these impurities; but by a second rectification in the current of hydrogen, when
the first portions were again rejected, a considerable improvement took place.
Parapicoline is a pale yellow oil of the consistence of a fixed oil, which ac-
quires a brown colour by exposure to the air. It is insoluble in water, although

582 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

it communicates its smell to that fluid when shaken with it. It dissolves in all
proportions in alcohol, ether, the fixed and volatile oils. It has a highly charac-
teristic empyreumatic smell, quite distinct from that of picoline, without pungency,
and closely resembling that of the bases extracted from the portions of Dippel’s
oil of very high boiling point, and which not improbably contain it. Its smell
adheres pertinaciously to the fingers. It fumes slightly when a rod dipped in
hydrochloric acid is brought near it, and restores the blue colour of reddened
litmus. Boiled with strong nitric acid, it gives off red fumes, and on dilution
with water a small quantity of a resinous matter deposits, but the greater
part of the base is separated unchanged on the addition of potash. It gives an
emerald-green precipitate with sulphate of copper, which dissolves in hydro-
chloric acid, and forms a green solution, containing a double salt. Most of its
compounds are uncrystallizable, and readily soluble in water. Its specific
gravity is 1:077, and it boils between 500° and 600° Fahrenheit, and is partially
decomposed. The portions employed for analysis were very carefully distilled
for that purpose. Owing to the high boiling point, some difficulty was expe-
- rienced in the combustion, and it was found convenient to weigh the substance
in a small open tube, which was passed into the combustion tube. The results
were,—

3°060 grains of parapicoline gave
a, 8-730 ... carbonic acid and
27158. ....)_, water
3°707 grains of parapicoline gave
II. ¢ 10601 ... carbonic acid and
2°605 ... — Water.
4:270 grains of parapicoline gave
III. <12:195 ... carbonic acid and
o072 yeocme. water:
Experiment. Calculation.
ha Ee nie a ae ie =
it I. It.
Carbon, ; : : 77°81 17:99 77°89 77-42 C,, 72
Hydrogen, . : "i 7:83 7:96 7:99 7°53 ie 7
Nitrogen, Soe dere : 15:05 N 14
10-000 93

These numbers correspond almost exactly with those of picoline itself, as in-
dicated by the calculation. The quantity of carbon in all the analyses is con-
siderably above that required by theory; but it is easy to understand how a
small quantity of empyreumatic matters formed during the decomposition may
produce this effect ; and itis sufficiently obvious that the base is isomeric with
picoline. This is further confirmed by the analysis of its platinum salt, which is

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 583

immediately precipitated when bichloride of platinum is added to a solution of
the hydrochlorate of parapicoline, as a pale yellow powder, almost insoluble in
water. The results of the analysis were as follows :—

r J 317 grains of platiochloride of parapicoline gave
2059 =~... ~—~pilatinum.

I 1 6:102 grains of platinochloride of parapicoline gave

1-970 .... , platinum:
Experiment. Calculation.
Ea To ——————
ie II.
Carbon, . d P dus Ms 24:07 Cio 72
Hydrogen, : ; ree oh 2°68 Hy, 8
Nitrogen, : : aM oe 4:67 N 14
Chlorine, i 3 Bee es 35°59 Cl, 106°5
Platinum, : . 92°59 32°28 32:98 12s 98-7
100:00 299:°2

These numbers correspond with the formula C,,H,N HCl PtCl,, which is
that of the picoline salt; and the analysis would thus lead us to the conclu-
sion that parapicoline is strictly isomeric with that base. But when its high
boiling point and other properties are taken into consideration, it is impossible
to resist the inference, that its real constitution must be different; and I believe
it ought to be represented by the formula C.,H,,N2, and that it is produced by the
combination of two equivalents of picoline. Unfortunately the high boiling point
of parapicoline precludes the determination of the specific gravity of its vapour ;
and as it is not possible in any other way to establish its true constitution, we
are compelled to assume, as the most probable hypothesis, that it is produced
by a species of reduplication, of which we have already numerous examples in the
other classes of organic compounds, although this is the first instance in which
it has been observed among the bases. The conversion of cyanic into cyanuric
acid is a completely analogous case, the more especially as the three equivalents
of cyanic acid which have combined retain their power of neutralizing as many
equivalents of base. The simultaneous production of amilene, paramilene, and
metamilene, during the action of sulphuric acid on amylic alcohol, may also be
referred to as cases in which a somewhat similar reduplication occurs. It is very
difficult to explain the mode in which the sodium produces the combination of
the two equivalents of picoline, but it may possibly be due to a species of catalytic
action, as a large quantity of the sodium employed is always recovered un-
changed. A certain quantity of it, however, enters into some sort of combination
with the picoline or parapicoline, to produce the resinous compound already
mentioned; and it appears most likely that this substance is a sodiopicoline,
represented by the formula C,,H,Na N, in which an equivalent of hydrogen has
been replaced by sodium. The action of water upon the resinous matter would
then be represented by the following equation :—

VOL. XXI. PART IV. 7s

584 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

2 (C,,H,Na N) + 2HO = ©,,H,,N, + 2Na0.

247714
If this be the case, hydrogen ought to be evolved during the action of sodium
on picoline, but owing to the slow nature of the action which takes place, I have
not been able to satisfy myself that such is the case.

Whatever be its nature, parapicoline must be considered a very remarkable
base, and altogether unique in the mode of its production, but it is completely
analogous in its constitution to nicotine, for the determination of the density of
the vapour of that base has shown incontestably that its rational formula is
C,,H,,N,, and that of its platinum salt, C,,H,,N 2HCl Pt,Cl,. I think it can
scarcely be doubted that nicotine, like parapicoline, has been formed by the
combination of two equivalents of a base boiling at a temperature not greatly
exceeding 212°, and which will some day be discovered. I have attempted to
reconvert parapicoline into picoline, but without success; for though the change
appears to be partially effected by rapid distillation, the process is not definite,
much carbonate of ammonia being produced.

Salts of Parapicoline.

The salts of parapicoline are chiefly uncrystallizable, and present but few
points of interest. I have therefore submitted them to a very cursory exami-
nation.

Sulphate of Parapicoline is obtained as a gummy mass, very soluble in
water, less so in alcohol. It shows no signs of crystallization.

Nitrate of Parapicoline is obtained by saturating nitric acid with the base,
and evaporating. A syrupy fluid is left, which slowly solidifies on cooling into a
mass of short needles. It is exceedingly soluble in water, less so in alcohol,
and it does not deliquesce.

Hydrochlorate of Parapicoline is an amorphous resin, very soluble in water.

Hydrargochloride of Parapicoline. A solution of corrosive sublimate imme-
diately gives an abundant curdy precipitate of this salt when added to an alco-
holic solution of parapicoline. It is insoluble in alcohol and in water, but is
instantly dissolved on the addition of a few drops of hydrochloric acid.

Aurochloride of Parapicoline, is a yellow insoluble amorphous substance,
decomposed at the boiling heat.

The details now given, as well as those contained in the preceding parts of
this investigation, may serve to illustrate with sufficient fulness the general
characters of the bases of the pyridine series. It remains for me only to direct
attention to their physical properties, which illustrate in a very striking manner
the relations subsisting between the different members of a homologous series.
The particulars of most of the experiments have been already given, and it is
only necessary to add those by which the specific gravity of the vapour of luti-
dine was determined.

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 585

Temperature of the air, ; : : 2 17° cent,

sie vapour, . 3 Ff ‘ DOr;
Excess of weight of the balloon, § 3 : 0-4493 grammes.
Capacity of do. : é ; ‘ 302 ¢. ¢,
Barometer, 5 ‘ : ; ; 776 m. m,
Residual air, ‘ , ; : : 0
Specific gravity of the vapour, i : : 3°839

The formula C,,H,N requires

14 vol. carbon vapour, = 0°8290 x 14=11-6060
18 vol. hydrogen, = 0:0692 x 18= 1:2456
2 vol. nitrogen, = 09713 x 2= 1:9426
147942
—___—.= 3'699
4

In the following table I have collected the whole of the data, all having been
carefully redetermined with much purer materials than those used in my ori-
ginal experiments,—

Specific Gravity.
Specific
Volume
Vapour. Liquid at 32° at 32°,

Formula. | Boiling Point.

Pyridine, C,,H;N | 242° 2:916 0:9858 80-1
Picoline, CEN 6275" 3-290 0-9613 96-7
Lutidine, C,,H,N 310° 3-839 0:9467 113-0
Collidine, C/HN |” 856° ee 0:9439 128-2

The boiling points of pyridine, picoline, and lutidine agree remarkably well
with Kopr’s law, but collidine differs very materially from it. Less reliance,
however, is to be placed upon the boiling point of the last substance, as it was
determined upon a very small quantity of material. The specific gravities of the
vapours agree very closely with theory, while those of the fluids themselves,
taken at 32°, illustrate also in a very remarkable manner the gradual diminution
which is observed when we ascend through a series of homologous substances.
To these experimental numbers have been added the specific volumes of the bases
at 32°, calculated from the data they afford: but no determinations of the co-
efficient of expansion of these substances having been made, it is not possible
to ascertain their specific volumes at the boiling points, although from the rapidity
of their expansion, I believe it will be found that the difference must approach
very closely to 22, which is that produced in non-nitrogenous substances by the
addition of C,H, to their atom.

586 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

Pyrrol.

Reference has frequently been made throughout the course of this investiga-
tion to the substance discovered by RunGeE* in coal-tar, and called by him pyrrol.
This substance he described as a gas, although he appears never to have prepared
it in a pure state, but simply to have obtained its very singular reaction with
fir-wood; and he mentions that it occurs in very small quantity, and accom-
panies the ammonia produced during destructive distillation. In the second part
of this paper, when describing the preparation of the bases from crude bone oil,
it was stated that the acid solution afforded on distillation a quantity of an oil
possessing in a high degree the characteristic reaction of pyrrol, and which was
decomposed when boiled with moderately concentrated acids, with the precipita-
tion of a red resinous matter, while the fluid was found to contain different num-
bers of the pyridine series of bases. From these facts I was led to infer that this
oil contained a series of bases in which pyridine and its homologues were coupled
with some substance which was separated by acids, and converted into the red
resin,—an opinion which further experiment has entirely refuted.

The oil collected during the distillation of the acid solution of the crude
pyridine bases, had a peculiarly fetid and disagreeable smell, and was at first
colourless, but soon acquired a reddish colour, and after a few days became
nearly black. When freed from water it began to distil about 250°, and a ther-
mometer placed in the tubulature of the retort gradually rose as the distillation
proceeded, until at length it reached nearly 400°. The greater proportion of the
oil passed between 280° and 310°, but large fractions were obtained at much
higher temperatures. All the fractions had a characteristic smell different from
that of the pyridine bases, and gave instantaneously the reaction of pyrrol. When
treated with acids, the red resinous matter was deposited, and the filtered fiuid,
on treatment with potash, evolved the smell of different members of the pyridine
series, according to the boiling point of the fraction selected for the experiment.
The oil containing pyrrol was now subjected to a systematic fractionation; and it
was found, after several rectifications, to manifest a decided tendency to concen-
trate itself towards a fixed point, the fractions collected between 270° and 280°, and
280° and 290°, greatly exceeding the others in bulk. The oil obtained at these tem-
peratures was perfectly transparent and colourless when freshly distilled, but
soon acquired a brown colour, though much less rapidly than the crude sub-
stance. When agitated with very dilute acids, a certain portion of it immediately
dissolved, but the remainder was very slowly acted upon, and required a large
excess of acid, and much shaking, in order to make it dissolve, which, however,
it eventually did completely. This fact appearing to indicate that the substance

* Poggendorf’s Annalen, vols. xxxi. and xxxii.

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 587

was a mixture, it was shaken up with a small quantity of dilute acid, and the
watery solution withdrawn. On the addition of caustic potash to this solution,
an oil separated, which had the smell of picoline mixed with that of pyrrol. For
the purpose of separating this picoline, the whole of the larger fractions were
mixed and shaken up with a small quantity of very dilute sulphuric acid, and
the solution, after being siphoned off, was replaced by another quantity, and
this was repeated a third time. The oil was thus diminished by about a third
of its bulk, and the whole of the picoline or other bases appearing to have been
removed, it was carefully dried by means of sticks of caustic potash, and again
rectified, when its boiling point was found to have been materially reduced. It
began to boil at much the same temperature as the crude oil, but the largest
fraction was now collected between 270° and 280°, while that which boiled above
290° formed only a very small proportion of the whole; and after fifteen rectifi-
cations, it was obtained in such a state that it distilled almost entirely between
274° and 280°. In this condition it is a transparent and colourless oil, slowly
acquiring a brown colour when exposed to air and light. It has a strong fetid
smell, quite distinct from that of picoline, and a hot pungent taste. A piece of
fir-wood, dipped in hydrochloric acid brought near its vapour, instantly acquires .
a fine red colour. When boiled with a dilute acid, it is immediately converted
into a red resinous mass, which fills the fluid so completely, that the vessel con-
taining it may be inverted without anything escaping. ‘The fluid filtered from
this substance is brown, and contains a small quantity of it in solution. After
boiling for some time, so as to get rid of a peculiar smell which adhered to the
fluid, and decompose the last traces of pyrrol, caustic potash was added, when
the smell of ammonia, faintly contaminated with that of picoline, was evolved.
The solution having been distilled, the ammonia was saturated with hydrochloric
acid and bichloride of platinum added, when the platinochloride of ammonium
was immediately precipitated, and the filtrate, on further evaporation, yielded
an additional quantity of that salt, along with some indications of a more soluble
platinum compound. For a long time I considered the oil prepared by the pro-
cess now detailed to be pyrrol in a state of as great purity as it was possible to
obtain it; and, as will be afterwards seen, it gave in different preparations,
analytical results in perfect accordance with one another, and with its true
formula ; but in the course of examining the effect of different reagents upon it,
it was found that caustic potash exerted a very singular and perfectly unique
action, disclosed the presence of a small quantity of some impurity, and afforded
the means of removing it, when the properties of the pyrrol underwent a very
remarkable change. When pyrrol is mixed with five or six times its weight of
caustic potash in coarse powder, and heated over the lamp in a flask fitted with
a long tube, it at first cohobates very freely ; but if the temperature be gradually
raised, the fluid is found to distil up into the tube much less readily, and at
VOL. XXI. PART IV. aE

588 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

length the bottom of the flask may be heated nearly red hot, while a very insig-
nificant quantity of oil distils up. In performing this process, glass flasks were
corroded by the caustic potash long before the action was complete, and it was
found very convenient to employ copper flasks made by the electrotype process.
A plaster of Paris mould was taken from a glass flask of convenient size and
shape; and from that a wax cast was made and electrotyped in the usual way.
After about a week the copper was sufficiently thick for use. In such flasks
pyrrol was boiled for a day or two with caustic potash, the heat being raised as
high as an Argand or Bunsen’s gas-lamp would bring it. A bent tube was then
fitted into the mouth of the flask, and the heat again applied, so as to distil off all
the oil that could be obtained. The distillate had the smell of pyrrol mixed more or
less distinctly with that of picoline, and the preponderance of the latter smell
depended on the quantity of potash having been sufficiently large to retain the
true pyrrol, which, however, it was not possible to do entirely, even when a very
large excess of potash was used. When the whole of this oil had distilled, the
bent tube was removed from the mouth of the flask, and the still fluid potash
poured out on a copper plate.

On cooling, it solidified into a hard white mass with a yellowish tinge, which,
when perfectly dry had no smell, but it was only necessary to breathe upon
it to cause it to exhale a delightful etherial and fragrant odour, not unlike
that of chloroform, but softer and less pungent. When thrown into water
the potash gradually dissolved, and a transparent and colourless oil col-
lected on the surface of the solution, from which it was separated either
by a pipette or by distillation. The potash solution on saturation with sul-
phuric acid evolved the smell of a fatty acid, and when distilled, yielded a
fluid which reddened litmus strongly, and had a smell resembling that of
valerianic acid. The distillate was saturated with carbonate of soda, and
the solution evaporated to complete dryness and extracted with absolute alco-
hol. The alcoholic fluid was again evaporated, the residue dissolved in
water, and a quantity of solution of nitrate of silver insufficient for com-
plete precipitation added to it, and the precipitate was collected on a filter
and washed. Another quantity of nitrate of silver was then added, and the
precipitate collected, and finally, enough of the nitrate was used to throw the
remainder of the fatty acids in the fluid. In this way three different silver

salts were obtained, which were separately analysed. The first precipitate
gave :—

6-273 grains of silver salt gave
6510 ... carbonic acid and
DAF vase | Wabers

5°192 grains of silver salt gave
2°697.- «..) . silver.

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS.

589

Experiment. Calculation.
Carbon, 28°30 Ds er Ups 50
Hydrogen, 4:34 4°31 Hi, 9
Silver, 51:94 51:67 Ag 108
Oxygen, nee 15-31 OF 32
100:00 209

which corresponds completely with the valerianate of silver. The second precipi-
tate was manifestly a mixture, and gave variable quantities of silver, generally
about 2 per cent. under that required by the valerianate. But the third precipi-
tate consisted of propionate of silver, as shown by the subjoined analyses :—

I. 5:002 grains of the third precipitate gave 2:993 grains silver.

II. 4:796 another preparation gave 3:848
Experiment. Calculation.
ag re Sy ET ee
i 10g Mean,

Carbon, . é es ee tik 19-89 C, 36
Hydrogen, . : oe vee eee 2-76 H, 5
Silver, : 59:83 59°38 59°50 59:66 Ag 108
Oxygen, : rs ee ae 17:69 O, 32

100-00 tA) LOT

It thus appears that the crude pyrrol contained a small quantity of some sub-
stances yielding valerianic and propionic acids when acted on by potash. The
exact nature of these compounds it was impossible to determine, as their quantity
was extremely minute, and the silver salts obtained from a very considerable
quantity of pyrrol, were no more than sufficient for the analyses just detailed.
The fragrant pyrrol separated from the potash solution by distillation is trans-
parent and colourless, when freshly prepared, but acquires a brown colour by
exposure to the air. Its taste is hot and pungent, and its smell pleasant and
etherial, and recalls that of chloroform. It is sparingly soluble in water, but
readily in alcohol, ether, and the oils. It is insoluble in alkaline solutions, but
the acids dissolve it, although not very rapidly. Its specific gravity is 1-077, and
it boils at 271°. It gives the remarkable reaction on fir-wood described by
RunceE in a very powerful manner. The reaction is best obtained by dipping a
piece of fir-wood in concentrated commercial hydrochloric acid, and holding it
near a vessel containing pyrrol, or in a current of its vapour; a pale pink colour
immediately makes its appearance, and gradually deepens to an intense carmine.
All kinds of fir-wood do not produce the reaction equally well, and it appears to
depend in some way upon the resin, for if fir saw-dust be extracted by alcohol
or ether, and bits of cotton or linen cloth dipped in the solution, they acquire the
property of becoming red, when exposed to pyrrol vapour, after having been
moistened with hydrochloric acid, although the colour is by no means so brilliant

590 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

as that developed on the wood itself. When agitated with cold dilute acids, pyrrol
dissolves unchanged, but on heating the solution, it deposits a red flocky sub-
stance, and if not too dilute, the whole is converted into a gelatinous mass, so that
the vessel may be inverted without anything escaping. The same change takes
place in the cold, when the acid solution is kept for some days. When bichloride
of platinum is added to a cold hydrochloric solution of pyrrol, it instantly becomes
dark coloured, and in the course of a few minutes an abundant black precipitate,
containing platinum, is deposited. When boiled with sesquichloride of iron, the
solution becomes first green, and finally black. Bichromate of potash also de-
composes it with the formation of an abundant black precipitate, and sulphate
of copper, when heated with it for some time, acquires a green colour, and a small
quantity of a black powder is deposited. It is rapidly oxidized by nitric acid,
with the evolution of abundant red fumes, and formation of a dark-red solution,
which, when diluted, permits a yellow resin to fall. By long-continued ebullition,
oxalic acid is produced. An alcoholic solution of pyrrol gives white precipitates
with corrosive sublimate and chloride of cadmium, but it does not precipitate the
metallic oxides generally.

The combustion of pyrrol was very easily effected, and the results are sub-
joined. The first six analyses were those of crude or fetid pyrrol, and are all from
different preparations except the first two. The last is that of the fragrant

pyrrol.

5'805 grains of pyrrol gave
I, < 15:250 ... carbonic acid and
{ 4-070 coe water:
3°675 grains of pyrrol gave
iD. 9-625 ... carbonic acid and
2°550 se. | Water:
5'250 grains of pyrrol gave
III. ¢ 18°830 ... carbonic acid and
3'675 ... water.
4-033 grains of pyrrol gave
IV. < 10°590 ... carbonic acid and
2-922 cea water.
4-706 grains of pyrrol gave
V. < 12-345 ... carbonic acid and
3°307 1) water!
5:280 grains of pyrrol gave
VI. < 13°845 ... carbonic acid and
3676 ... water.
5-213 grains of fragrant pyrrol gave
VII. ¢ 13°675 ... carbonic acid and
3°649 ... Water.

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 591

I. IL. III. IV. V. VI. VII. Mean,

Carbon, . . 71:64 71:42 71:84 71°61 71:54 71-51 71:54 71:58
Hydrogen, a Oy, ae OTE 8:05 7°80 TT4 Crk 7°85
Nitrogen, bee cn a ae a ote nie 20:57
100:00

These results correspond with the formula C,H;N, which requires the fol-
lowing numbers :—"

8 eq. carbon = 48 71:64
5 ... hydrogen, = 5 7°46
1 ... nitrogen, = 14 20°90

67 100-00

As none of the compounds of pyrrol are sufficiently definite to admit of their
being used for fixing its atomic weight, recourse was had to the determination of
the density of its vapour for this purpose, and three experiments were made at
different stages of the investigation. The first was made after the pyrrol had
received six rectifications and one treatment with acid, and its deviation from
that required by theory showed that the material was not yet quite pure. The
second, made after fourteen rectifications, and agitation with three successive por-
tions of sulphuric acid, showed a close approximation to the theoretical number,
while the third, made with the fragrant pyrrol, was as exact as could be desired.
The details are as follow :-—

‘ I. II. IIT.
Temperature of the air, ; : 16° ¢. AG 13°
Be vapour, . : 198° 186° 201°
Excess of weight of the balloon, . 5 0:2285 grammes. 0°2185 01610
Capacity of do. . : : ? 324°5 ¢. ¢. 328°5 303
Barometer, : : : : 767 m. m. 744 764
Residual air, : . : : 0 1:5 4
Density of the vapour, . : 3 2°52 2°49 2°40
The formula C,H, N requires :—
8 vol. carbon vapour, 0°8290 x 8 = 6:6320
10 ... hydrogen, -- 0:0692 x 10 = 0-6920
2... nitrogen, -- 09713 x 2 = 1:9426
9-2666
—_—- = 231
4

Although the properties of the pyrrol now described are entirely distinct from
those attributed to this substance by Runes, it cannot be doubted that they are
really identical, although it is equally unquestionable that he never isolated his
pyrrol, but merely obtained a small quantity of it held in solution by some gas,
most probably a hydrocarbon. For thisreason I think it right to retain his name,

VOL. XXI. PART Iv. EG

592 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

although it is not formed in accordance with the received nomenclature of organic
compounds, the more especially as it would be difficult, in the present state of our
knowledge, to find another which would not be open to many objections. As far as
its properties and chemical relations go, pyrrol approaches more nearly to the vola-
tile organic bases than to any other class of nitrogenous compounds, but its basic
properties are extremely weak, as it has no effect on test papers, and though
soluble in dilute acids, can be expelled from the solution at the boiling heat. It
forms, however, compounds with corrosive sublimate and chloride of cadmium,
both of which are easily decomposed.

Mercury Compound of Pyrrol.—This substance is obtained by mixing alcho-
holic solutions of pyrrol and corrosive sublimate, when it is immediately precipi-
tated as a white powder with a somewhat crystalline appearance, insoluble in
water, and sparingly soluble in cold alcohol. It is more soluble on boiling, but
is then partially decomposed. Excess of corrosive sublimate appears also to act
upon it in some way, as the solution from which it has been deposited acquires,
on standing, a dark red, and sometimes a fine purple colour, due, in all probabi-
lity, to the oxidation of pyrrol. The substance employed for analysis was dried
in vacuo, and was from different preparations :—

7°186 grains of mercury compound gave

I 2:079 ... Garbonic acid.

II 2-472 ... carbonic acid and

8:906 grains of mercury compound gave
0-652 --. water.

III 7131 grains of mercury compound gave

ey ara wen aDErcury.
Experiment. Calculation.
—_—_—_——. —_—_—_—_—_—_—_—_———eaeeee

7 II.
Carbon, ; : , 7:89 7:57 7:88 C, 48
Hydrogen, . : : sas 0-81 0:82 H, 5
Nitrogen, : - Sec bse 2°31 N 14
Chlorine, : : : Sac ate 23°31 Cl, 142
Mercury, : : : oe 66°89 65:68 Hg, 400
100-00 609

Corresponding with the formula C,H, N + 2 Hg Cl..

Cadmium Compound of Pyrrol is obtained as a white crystalline powder, when
alcoholic solutions of pyrrol and chloride of cadmium are mixed. It is insoluble
in water, but dissolves readily in hydrochloric acid. It is rapidly decomposed
when heated, either dry or in suspension in water or alcohol. Its analysis gave

4:837 ... earbonic acid and

5°673 grains of cadmium salt gave
POROe f See ee Waele

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS.

Experiment. Calculation.
Carbon, 23:25 23°50 Cie 96
Hydrogen, 2:19 2°44 13 Oe 10
Nitrogen, 5 6:87 iN 28
Cadmium, 41-12 Cd, 168
Chlorine, 26:07 Cl, 1065
100:00 408°5

593

This agrees pretty closely with the formula 2 (C, H, N)+3Cd CL.

Products of the Decomposition of Pyrrol.

The decompositions of pyrrol have not led to results as definite as might have
been anticipated; and I have therefore restricted myself to the examination of
the red matter produced by the action of acids, and even that has been attended
with no little trouble and difficulty.

Pyrrol Red.—This substance, as has already been frequently observed, is
produced whenever pyrrol is boiled with an excess of acid; but notwithstanding
the apparently definite nature of the change, itis extremely difficult to obtain it of
uniform composition. This is due in part to its tendency to retain a small quantity
of acid, and in part also to the fact that continued boiling produces a farther
action, attended by the production of a dark colour in the acid liquid. When
this occurs, the red matter gives very variable results when analysed, and hence,
owing to the impossibility of ascertaining the exact length of time during which
the fluid should be boiled to insure complete formation of the red matter, with-
out going too far, the results of the analyses are by no means as concordant as
might be desired. After a good many trials, it was found that the most success-
ful results were obtained in the following manner :—Pyrrol was dissolved with
the aid of brisk agitation in sulphuric acid diluted with from four to six parts of
water, and the solution heated over the gas flame, while the flask was constantly
shaken. As soon as thered matter had separated in distinct flocks, it was thrown
on a filter and rapidly washed with boiling water, until the acid was almost
entirely removed, during which process the pyrrol red acquired a slightly brown
colour on the surface. A small quantity of diluted caustic potash was then
poured upon the filter, when the product immediately became of a fine orange
colour, which it retained after having been washed free of potash.

Pyrrol red is a fine, light, porous substance, with an orange-red colour, which
becomes slightly brown by exposure to the air, especially when heated. It is in-
soluble in water, and is not readily moistened by that fluid. It is slightly soluble
in cold, more so in boiling alcohol; and is again deposited on cooling in amor-
phous flocks. It is sparingly soluble in ether. Neither acids nor alkalies dissolve
it, but if boiled with them for some time it is decomposed. Nitric acid oxidizes
it, with the production of a resinous substance; and if the action be continued fora
sufficient length of time, oxalic acid is found in the solution. When heated in

594 PROFESSOR ANDERSON ON THE PRODUCTS OF THE

close vessels it yields an oil of an extremely offensive odour, and which gives the
reactions of pyrrol, while a bulky charcoal is left in the retort. In the open air
it catches fire, and burns readily. When exposed to 212° in the water-bath, it
gains weight, owing to slow oxidation; and the portion used for analysis was
therefore dried 7m vacuo. The results were—

16:770 ah carbonic acid and

6°381 grains of pyrrol red dried in vacuo gave
AT72 | a » ‘water.

6°440 grains of pyrrol red gave

0846 ... nitrogen.

6-910 grains of pyrrol red gave
18816 ... carbonic acid and

Al ice gon \ Wael

III.

6-048 grains of pyrrol red gave

IV. 16:054 a carbonic acid and

3°764 ... water
V. 6:578 i of pyrrol red gave
nitrogen.
6-132 grains of pyrrol red gave
VI.<{ 16-248 ... carbonic acid and
3793 ... . water.
II. TH. Iv. ws VI. Mean.
Carbon, % . a7. eae "52 iy re Sr 72°45 ove 72:20 71:98
Efydropen, 9. 8y |) 7:29 =F 6-70 6°66 V2: 6°87 6:88
Nitnogens, (, aprit Sq pleas 13:14 193 ads 14:05 _ 13°58
Oxyveeu, «ach a Reese? tbs efi i ee se 7°56
100°00

These results approximate most closely to the formula C,, Hi, N.,0O2, which
requires

24 eq. carbon, ’ F ‘ 144 71-28
14... hydrogen, . , ' 14 6:93
2... nitrogen, . , : 28 13°86

2... oxygen, 4 : 3 16 7:93
202 100-00

It is true that the numbers obtained by analysis do not accord well with this
formula, and in particular the carbon is materially in excess, but this is undoubt-
edly due to a further decomposition produced by boiling; for if the heat be con-
tinued for some time during its preparation, the red matter acquires a dark-
brown colour, and contains as much as 74 per cent. of carbon. The nature of
the change by which the red matter is produced is readily intelligible, and is
thus represented :—

3 equivalents pyrrol, : - : piel 3 ye a

—I1 eq. ammonia, H, N
C,, Hy, No

+ 2 eq. water, H O

1 eq. pyrrol red, . ‘ r 5 : C,, Hy, N, 9,

DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 595

The formation of ammonia during this decomposition was demonstrated by
distilling the acid filtrate from the red substance with potash. The distillate,
which had the smell of ammonia contaminated with an empyreumatic odour,
and sometimes with that of picoline, was saturated with hydrochloric acid, and
evaporated with excess of bichloride of platinum to nearly complete dryness.
Octahedral crystals of platinochloride of ammonium were deposited, which were
examined under the microscope, and found to be free from any other salt.

The quantity of pyrrol contained in bone-oil is far from inconsiderable, and
now that its properties have been investigated, it is easy to see that a great deal
must have been destroyed during the treatment by which the crude bases were
extracted. As my previous investigation of the picoline from coal-tar had shown
that its neutral sulphate is converted into bisulphate by boiling, I took care to
add to the crude sulphates extracted by agitating bone-oil with sulphuric acid, a
large excess of acid before boiling it for the purpose of separating pyrrol; and
in this way large quantities of the red matter in an impure state were produced
during the early part of the investigation. It was only after I had advanced
some way in the investigation that the cause of its formation became in-
telligible, and the crude sulphates were then distilled without the addition
of acid, and the pyrrol mixed with empyreumatic oils and bases of the pico-
line series was obtained in quantity sufficient for investigation. The diffi-
culty experienced in removing the last traces of pyrrol from the bases was very
great, and it was necessary to boil the solution for several days; but I have now
found that oxidizing agents, such as nitric acid, or, still better, bichromate of
potash, offer invaluable means of purification, as they decompose the pyrrol with-
out producing the slightest effect on the bases.

In the present and preceding parts of this investigation, I have directed atten-
tion to the basic constituents of bone-oil. In the next part, I propose to treat of
its non-basic constituents, in the investigation of which some progress has already
been made. In particular, it has been found that, by repeated rectifications, a
fine volatile fluid, boiling as low as 150° Fahr., is obtained. This oil consists of
at least two different substances, separable by means of a freezing mixture,
which causes the fluid to divide into two perfectly distinct strata, with a well-
marked line of separation. The higher fractions do not present this peculiarity,
but they are also complex, containing benzene, and apparently some of its homo-
logues, along with the alcohol radicals of the fatty series, and also nitrogenous
compounds decomposable by alcoholic solution of potash and by sodium.

VOL. XXI. PART IV. tex

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XXXVI.—On the Application of the Theory of Probabilities to the Question of the
Combination of Testimonies or Judgments. By Grorce Boote, LL.D., Professor
of Mathematics in Queen’s College, Cork. Communicated by Bishop Terror.

(Read 19th January 1857.)

1. The method for the solution of questions in the theory of probabilities ap-
plied in this paper, is that which was developed by the author in a treatise entitled,
« An Investigation of the Laws of Thought, on which are founded the Mathema-
tical Theories of Logic and Probabilities.” The practical object of the paper is to
deduce from that method certain conclusions relating to the combination of tes-
timonies or judgments. Beside this, however, it will have a speculative reference
to some more general questions connected with the theory of probabilities; and
especially to the following question, viz.: To what extent the different modes in
which the human mind proceeds, in the estimation of probability, may be consi-
dered as mutually confirming each other,—as manifestations of a central unity
of thought amid the diversity of the forms in which that unity is developed.

The special problems relating to the combination of testimonies or judgments
which are considered in this paper are the following: 1st, That in which the
testimonies to be combined are merely differing numerical measures of a physical
magnitude, as the elevation of a star, furnished by different observations taken
simultaneously ; 2d/y, That in which the testimonies or judgments to be combined
relate not to a numerical measure, but to some fact or hypothesis of which it is
sought to determine the probability,—the probabilities furnished by the separate
testimonies or judgments constituting our data.

2. I have, in the treatise to which reference has been made, described the
method which will be practically applied in this paper as a general one. It will,
I think, ultimately appear that there is a true and real sense in which the pro-
priety of the description may be maintained. But at present I am anxious to
qualify the appellation, and to speak of the method as general only with respect
to problems which have been resolved into purely logical elements, or which are
capable of such resolution. A more thorough analysis of the mental phenomena of
expectation will, I think, tend to establish the position that all questions of proba-
bility, in the mathematical sense, admit of being resolved into primary elements
of this nature, or, to speak more strictly, admit of being adequately represented
by other problems whose elements are logicalonly. Postponing the consideration
of this question, I will first endeavour to explain what is meant by the logical
elements of a problem, and how the consideration of such elements affects the
mode of its solution.

VOL. XXI. PART IV. oy

598 PROFESSOR BOOLE ON THE COMBINATION

I regard the elements ofa problem relating to probability as logical, when its data
and its queesitum are the probabilities of events. The reason for this appellation
will shortly be seen. In expression, events may be distinguished as simple or com-
pound. A simple event, 7.¢., an event simple in expression, is one which is expressed
by a single term or predication; a compound event, one which is formed by
combining the expressions of simple events. “It rains,’—“it thunders,” would
be simple events; ‘it rains and thunders,”—“‘it either rains or thunders,” &c.,
would be compound events. The constructions by which such combinations are
expressed, although they belong to language, have their foundations in Logic.
Thus the conjunctions and, either, or, &c., express merely certain operations of
the faculty of Conception, the entire theory of which belongs to the science of
Logic. The calculus of Logic, to which I shall have occasion to refer, is a deve-
lopment of that science in mathematical forms, in which letters represent things,
or events, as subjects of Conception, and signs connecting those letters represent the
operations of that faculty, the laws of the signs being the expressed laws of the
operations signified. It is simply a mistake to regard that calculus as an attempt
to reduce the ideas of Logic under the dominion of number. Such are the grounds
upon which the class of problems to which I have referred are said to involve
logical elements. The description is, however, not entirely appropriate, for the
problems, as they are concerned with probabilities, in the mathematical accepta-
tion of that term, involve numerical as well as logical elements; but it is by the
latter that they are distinguished, and of them only is account taken in the no-
menclature.

Thus, as an illustration of what has been said, that problem would be com-
posed of logical elements, which, assigning for its numerical data the probabilities
of the throwing an ace or six with each single die, should propose to determine the
probability that the issue of a throw with two dice should be two aces, or that it
should be an ace and a six, or that it should be either two aces or an ace and a
six; and so on for any conceivable throw with any number of dice.

3. In the above example, the events whose numerical probabilities are given are
simple events, of which the event whose probability is sought is a logical combina-
tion. But it might happen that the former events were themselves combinations
of simple events. For instance, the data might be the probabilities that certain
meteorological phenomena, as rain, thunder, hail, &c., would occur in certain de-
finite combinations, and the object sought might be the probability that they
would occur in certain other combinations; all these combinations being, such
as it is within the province of language to express by means of conjunctions,
and of the adverb not. Now this would still be a problem whose elements are
logical.

4, But there are questions universally recognised as belonging to the theory
of probabilities, whose elements cannot, in their direct significance, be regarded

OF TESTIMONIES OR JUDGMENTS. 599

as logical. The problem of the reduction of astronomical observations belongs to
this class. Two observers, equally trustworthy, take an observation at the same
place and time of the altitude of a star. One of them declares that it is 50° 207,
the other that it is 50° 22’. From these data, what shall we regard as the most
probable altitude? We cannot, in this case, directly affirm that the numerical
data are measures of probability at all. They are conflicting measures of a phy-
sical magnitude. And that which is sought is not the measure of a probability,
but the most probable measure of the same magnitude. This is a problem evi-
dently of a different kind from the one which we last considered. And accord-
ingly it will be found that the principles of solution which have been actually
applied to it are different from, perhaps we ought rather to say supplementary to,
those which have sufficed for the solution of the others. In the problem of the
dice, we have only to apply, and that directly, such principles as the following,
viz., that when the probability of the occurrence of an event is p, that of its
non-occurrence is 1—p; that if the probabilities of two independent events are
p and q, that of their concurrence is pq; andsoon. In the reduction of the con-
flicting elements of the observers’ problem, another and quite distinct principle
is usually employed, viz., the principle of the arithmetical mean, which affirms
that if two different values are, on equal authority, assigned to a magnitude
which is in itself single and definite, the mind is led to consider the arithmetical
mean of those values as more likely to be its true measure than any other value.
This is not the only principle which has been employed for the reduction in
question. We shall refer to others. But it may justly be regarded as the most
obvious of all which have been employed; and there is ground for considering it,
as some eminent writers have expressly done, as primary and axiomatic in its
nature.

5. The following is the typical form of problems whose elements are logical.
If we represent the simple events involved in their expression by a, y, z,&c., then
may all their data (we will suppose the number of data to be 7) be expressed, in
accordance with the principles of the calculus of Logic, under the general forms

COUN Die (ty Up cee pee EON. (a, , 2.) po, +. Prob. @, (@,Y, 2: -)=Dn,
and the queesitum, or object sought, will be the value of

Prob. ibe (Gyafyz sss)

where ¢,, ¢,, -- p. and denote different but given logical functions of «, y, z.

Although the method for the solution of questions in the Theory of Probabi-
lities whose elements are logical has been developed at considerable length in a
special chapter of the Laws of Thought, yet much that is essential for its proper
and distinctive exhibition, has only been discovered since the publication of that

work. For this reason it will be proper to offer some account here of the princi-
ples upon which the method rests.

600 PROFESSOR BOOLE ON THE COMBINATION

6. I define the mathematical probability of an event as the ratio which the
number of distinct cases or hypotheses favourable to that event bears to the
whole number of distinct cases possible, supposing that to none of those cases
the mind is entitled to give any preference over any other. Fundamentally, this
definition agrees with that of Lartace. “La théorie des hazards consiste,’ he
remarks, ‘a réduire tous les évenements du méme genre a un certain nombre de
cas également possibles c’est a dire tels que nous soyons également indécis sur leur
existence et a déterminer le nombre de cas favorables 4 l’événement dont on
cherche la probabilité. Le rapport de ce nombre a celui de tous les cas possibles
est la mesure de cette probabilité.”—Essai Philosophique sur les Probabilités.

It is implied in this definition, that probability is relative to our actual state
of information, and varies with that information. Of this principle LapLace
gives the following illustration :—* Let there be three urns, A, B, C, of which we
are only informed that one contains black and the other white balls; then, a ball
being drawn from C, required the probability that the ball is black. As we are
ignorant which of the urns contains black balls, so that we have no reason to
suppose it to be the urn C rather than the urn A or the urn B, these three hy-
potheses will appear equally worthy of credit, but as the first of the three hypo-
theses alone is favourable to the drawing of a black ball from C, the probability
of that event is }. Suppose now that, in addition to the previous data, it is
known that the urn A contains only white balls, then our state of indecision has
reference only to the urns B and C, and the probability that a ball drawn from
C will be black is }. Lastly, if we are assured that both A and B contain white balls
only, the probability that a black ball will issue from C rises into certitude.”—
Essai Philosophique sur les Probabilités, p. 9.—(Phil. Mag., p.483.) Our estimate
of the probability of an event varies not absolutely with the circumstances which
actually affect its occurrence, but with our knowledge of those circumstances.

7. When the probabilities of simple events constitute our only data, we can,
by virtue of the above definition, determine the probability of any logical combi-
nation of those events, and this either, 1s¢, absolutely; or, 2d/y, conditionally.
The reason why we can, in this case, more immediately apply the definition is,
that not only is no connection expressed among the events whose probabilities are
given, but none is implied, nor is any restraint imposed upon their possible com-
binations. This, as we shall see, is not the case when the data are the probabi-
lities of compound events.

As an example, let us suppose that the probability of the conjunction of two
events, w and y, is required, the data being simply that the probability of the
event w is p, and that of the event y is g. Or, to express the problem in a form
which we shall hereafter generally employ:

Given Prob. «=p, Prob. y=q,

Required Prob. « y.

OF TESTIMONIES OR JUDGMENTS. 601

Let a be the number of distinct cases favourable to the event x, out of m dis-
tinct cases equally possible, from the comparison of which the probability p has
been assigned to the event z. In like manner let b be the number of distinct
cases favourable to the event y, out of m distinct cases equally possible, from the
comparison of which the probability g has been assigned to the event y. Then,

a

—— and kas
miei: rare

Now the conjunction zy can only come to pass through the combination of
some one of the @ cases in which 2 happens, with some one of the 6 cases in which
y happens, at the same time that we have an equal right to suppose that any one
of the m cases in which x happens or fails may combine with any one of the n
cases in which y happens or fails. To none of these combinations is the mind
entitled to attach any preference over any other, Hence there exist ad distinct
cases favourable to the conjunction of # and y out of a total of mn distinct and
equally possible cases. Thus, by the definition, the probability of the conjunc-

tion of 2 and y will be represented by the product a or pq.

Here the question may be asked,—Does, then, no difference exist between the
case in which the events # and y are known to be independent, and that in which
we are simply ignorant of the existence of any connection between them? I
reply that there is none, so far as the numerical estimation of probability is con-
cerned. There is, however, an important difference as respects the practical
value of the numerical result. If the events # and y are known to be inde-
pendent, and to have probabilities p and g, we know that, in the long run, the
conjunction xy will tend to recur with a frequency which will be proportional
to the magnitude of the fraction pg, We do not know that this will be the case
if we are simply ignorant of any connection between w and y. This is the differ-
ence referred to, and it is an important one. But it does not affect the calcula-
tion of probability as flowing from the definition of its numerical measure.

8. As from the data Prob. x=p, Prob. y=g, we deduce Prob. zy=pq, So from the
same data we should have, adopting the language of the calculus of Logic,

Prob. «(1—y)=p(1—g) Prob. (1—a) (1—y) =(1-p) (1-9),

and soon. Here #(1—y) denotes the compound event which consists in the oc-
currence of « conjointly with the non-occurrence of y; (1—«(1—y), the compound
event which consists in the joint non-occurrence of both w and y.

Extending this mode of investigation, we arrive at the theorem

Prob, PG; 9; 20s) = Op; ¢, T's.) : d (1)
where #, y, z, &c., denote any simple events whose probabilities (our only data)
are p, 7,7 .., and # (a, y, z..) denotes any event which can be expressed by

VOL. XXI. PART. IV. 72

602 PROFESSOR BOOLE ON THE COMBINATION

means of the simple events a, y, z, &c., in accordance with the notation of the
calculus of Logic.

By the above theorem the probability of any compound event is determined
absolutely, when the probabilities of its simple components are given.

9. And by the same mode of investigation, the probability of any combination
may be determined conditionally, 7.¢., the probability which the combination will
have under a given condition consisting in the happening of some other combina-
tion. Thus, if our data are as before,

Prob.,2=p; Prob: 40. Prob. z=r, &e.
and if we require the probability that if the event @(a, y, z..) present itself, the
event y (x, y,z..) Will be present at the same time, we may demonstrate the fol-
lowing result, viz. :—
Prob. that if $ (#, y,z..) happen, (a, y, z..) will be present also
Diy, :
és ae sais ca

where the form of the function x is determined by multiplying together, ac-
cording to the principles of the calculus of Logic, the functions#(a, y, z. .) and
) (w,y,2.-), and representing the result by x (a, y, z . .)—(Laiws of Thought, p. 258,
Prop. I.)

10. I postulate that when the data are not the probabilities of simple events,
we must, in order to apply them to the calculation of probability, regard them,
not as primary, but as derived from some anterior hypothesis, which presents the
probabilities of simple events as its system of data, and exhibits our actual data
as flowing out of that system, in accordance with those principles which have
already been shown to be involved in the very definition of probability.

The ground of this postulate is, that to begin with the simple and proceed to
the complex, seems to be, in all questions involving combinations such as we are
here concerned with, a necessary procedure of the understanding. The calcula-
tion of probability depends upon combinations subject to a peculiar condition,
viz., that they shall always present to us a series of cases or hypotheses, to none
of which the mind is entitled to attach any preference over any other. We can-
not, in endeavouring to ascend from the complex to the simple, secure the main-
tenance of this condition; but we can do so in descending from the simple to the
complex. We have had an illustration of this truth in the reasoning by which
we deduced the expression for the probability of the complex event zy from the
probabilities of the simple events xz and y, supposed to be given. And the me-
thods which have been actually employed in the solution of problems whose im-
mediate data were not the probabilities of simple events, have in fact rested upon
the postulate above referred to. Thus in questions relating to juries, the imme-
diate data are the probabilities, founded upon continued observation, that a de-
cision will be unanimous, or that it will be pronounced by a given majority, &c.

OF TESTIMONIES OR JUDGMENTS. 603

But it is usual, in solving these problems, to regard such events as com-
pound, and to derive them from a hypothesis which presents as its scheme or
system of data, the probabilities of individual correctness of judgment in the
members of the jury; the correctness of judgment in any such members being
regarded as a simple event. And this mode of procedure is a very natural and
very obvious one. For the degree of unanimity of a decision will so far depend
upon the correctness of judgment in the members, that, if we knew what the
probability of correctness in each member was, we could determine @ priovz the
probability of any proposed measure of agreement in the body.

The only question which arises, indeed, is not concerning the necessity of the
postulate, but concerning the mode in which it may be lawfully applied. How
shall we lawfully construct the hypothesis by which the solution of a problem
shall be made to depend upon the consideration of simple events. In answering
this question, I will endeavour to show, 1sé, upon what the construction of the
hypothesis does not depend; 2d/y, upon what it does depend.

11. The legitimate construction of the hypothesis in question cannot depend
upon the accidents of language, or causes deeper than accident, which have led
us to express particular things or events by simple terms, thus regarding them .
as simple events; and other events by combinations of these simple terms, thus
presenting them as compound. The solution of a question in the theory of proba-
bilities must depend upon the 7vformation conveyed in the data, not upon the
peculiar elements and constructions of the language which is the vehicle of that
information. Languages differ widely in these respects. Objects and events
which in one language are expressed by simple terms, are in another expressed
by combinations of simple terms. It is affirmed that a perfectly general method
of solution must be independent of, and superior to, differences like these.

I will endeavour to illustrate this principle by an example. Let the problem
to be resolved be the following. The probability of the concurrence of rain and
snow is p, of the concurrence of snow and wind q and of the concurrence of wind
and rain 7; required the probability of the concurrence of wind, rain, and snow.

Now suppose that we had to interpret the problem into a language in which
there were no simple terms corresponding to the simple terms “ wind,” “rain,”
“snow,” but in which there were simple terms for the three first of the concur-
rences above described.

We may, for simplicity, suppose that language to be a dialect of English, and
the concurrence of rain and snow to be represented in it by the term “sleet,”
the concurrence of snow and wind by the term “ drift,” and the concurrence of
wind and rain by the term “storm.”

The event whose probability is sought, viz., the concurrence of rain, snow, and
wind, would, in such a language, be represented by the combination either of two
of the terms above defined (as of sleet with drift), or of all the terms together,

604 PROFESSOR BOOLE ON THE COMBINATION |

since the presence of any two of the phenomena “sleet,” “ drift,” “storm,” im-
plies that of the third, and involves the conjunction of the phenomena of rain,
snow, and wind.

The data of the problem we are considering might then, in the imagined dia-
lect, assume the following form :

The probability of sleet is p, of drift g, and of storm 7; required the probabi-
lity of the concurrence of the phenomena of sleet, drift, and storm.

But in this form the problem would not, in its data, express all the knowledge
which the person using such language must possess of the connection of the events
to which it related. He must know that it was impossible that any two of the events
sleet, drift, and storm, should occur without the third, so that the problem, if so
stated as to embody the same amount of actual knowledge as is conveyed in the
previous statement of it, would assume the following form :

The probability of sleet is p, of drift g, of storm 7, and these events are so
connected, that no two of them can occur without the third occurring, What is
the probability of their concurrence?

Now the principle affirmed declares that the solution of the problem must be
the same whichsoever of these forms of statement we adopt.

As languages increase in affluence, the number of their simple terms becomes
augmented, partly through the necessity of giving expression to new ideas, partly
through the wish to give more convenient expression to definite and oft-recurring
combinations of the old ones. With every term invented in subserviency to the
latter purpose, a definition must be introduced. A dictionary, setting aside its
philological portion (and even this not wholly), isa record of such definitions. As
a consequence of such definitions of terms, spring up also propositions innumer-
able connecting these terms—propositions which in no degree add to the amount
of our absolute knowledge, which are quite distinct from the discovered facts and
laws of nature and of human history, but are merely logical deductions from
the definitions. We might conceive of a language in which all possible combi-
nations of ideas should be expressed by simple terms, with connecting definitions
and propositions ad infinitum. The realization of such a conception is neither
practicable nor desirable; but it is, nevertheless, the /imzt toward which all lan-
guages, which are not dead or decaying, do actually tend. The progressive ac-
tion of this tendency does not affect the laws of expectation, neither, therefore,
can it affect any consistent and scientific theory which is founded upon those
laws.

Weare not, therefore, permitted to assume that any events which, in the lan-
guage of the problem, may be presented as simple events, must therefore be
adopted as such into the hypothesis which is to form the basis of our method of
solution. Nor, on the other hand, are we forbidden to employ transformations
(sanctioned by the rules of Logic) which will have the effect of introducing an

OF TESTIMONIES OR JUDGMENTS. 605

entirely new scheme of simple events as the elements of the hypothesis in
question.

12. To what conditions, then, must the hypothesis be subject? This ques-
tion I now proceed to answer.

The hypothesis must be such that it may be consistently applied, without
imposing upon the data any other conditions than those of possibility, 7.¢., of
accordance with a possible experience.

This principle is so obviously true, that it will only be needful to show how
the conditions of possible experience are discovered. I shall subsequently show
how their discovery limits and determines the hypothesis upon which the solution
of questions in the theory of probabilities, whose elements are logical, depends.

The data of such problems are the probabilities of events. The object sought
is also the probability of an event. The numerical values of these probabilities
must be expressible by positive proper fractions. At any rate, they must not
transcend the limits 0 and 1. This is one condition to which they are subject.
Generally, however, there will exist other conditions dependent upon the mutual
relations of the events whose probabilities are given.

Thus, if p were the probability that an event 2 will happen, ¢ the probability —
that 2 and y will both happen, we have, as a necessary condition,

p>?

Again, if p were the probability that # and y will both happen, g the proba-
bility that they will both fail, we must have the condition,

pt+q<l

a condition which does not hold in the previous case.

I have, in the Laws of Thought, treated of these conditions, and of the prin-
ciples by which they may be determined, in a special chapter (Cap. xix., On
Statistical Conditions). A more simple, and at the same time perfectly general
method, for their determination was afterwards discovered by me, and published
in the Philosophical Magazine, Aug. 1854. As the method is of fundamental im-
portance, I shall here illustrate it by an example, at the same time introducing
a slight change in the mode of treatment, which leaves nothing to be desired
in point of simplicity. The conditions to the discovery of which the method
is applicable will be termed, in accordance with the language employed in the
Philosophical Magazine,—the “ Conditions of Possible Experience; inasmuch,
as whenever the numerical data of a problem are derived from actual experience
these conditions will be satisfied, and whenever in data professing to be thus
derived they are not satisfied, the presence of mistake or fraud may with certainty
be affirmed.

VOL. XXI. PART IV. Sa

606 PROFESSOR BOOLE ON THE COMBINATION

Determination of the Conditions of Possible Haperience.

13. To explain the method of effecting this object, by an example, I will first
symbolically express the problem of Art. 11.

Let us then represent rain by x, snow by y, and wind by z. The problem in
question then takes the following form:—

Given Prob. zy=p, Prob. yz=q, Prob. az=r : (1)

Required Prob. xyz . : . ; : ; (2)

The value required we shall represent by w. It is our present object, not to solve
this problem, but to ascertain the conditions which must connect p, g, and r,
in order that the data may be possible, with the corresponding limitations of w.
For if w were itself determined by experience, it would be subject to conditions
of possibility similar to those which govern p, q, and 7.
Now let us write, resolving the events in the problem into the possible alter-
nations out of which they are formed,
Prob. ayz=u, Prob. wyz=A, Prob. zzy=, Prob. yza=¥-
We have then
u+A=p, UtV=4q,; uUt+p=r : : : (3)
The first of these equations only expresses that the probability of the concurrence
of « and y is equal to the probability of the concurrence of z, y, and z, and the
probability of the concurrence of z and y without z. To the equations (3) we
must now add the inequations
a0, ASO" Wien eee %
utA+ptvel (4)
expressing the conditions to which wu, A, w, y, 1st, as probabilities, and, 2dly, as
probabilities which do not altogether make up certainty, are subject.
First, we will eliminate A, vy, and y. Their values found from (3) are

A=p-—u p=r-u y=q—-Uu.
Substituting these in (4) we have
u=0 p—us0 g—us9 r—u—0
ptqtr—2u =l,
Whence, 4 a
U=pP, Uae U=T, |
u=0, us prqerat { . . . (5)

Such are the conditions to which the quantity wu is subject, conditions which the
value of Prob. zyz must @ priori satisfy.

To determine the conditions connecting p, g, and 7, we must from (5) eliminate
u. Now, if we have any two inequations of the form

U=a usb

OF TESTIMONIES OR JUDGMENTS. 607

the only condition connecting a and 6 which they establish is,
a> b.

Applying this principle to (5), we have

= = +g+r—1
pater «pS Bi.
q>0. Ge CT -

= = ptqtr-1
rs). rs Mao a

These may be reduced to the somewhat simpler form
PaO iid 4 s0
p>qtr-1
g>r+p—-1
r>ptq-l |

Such are the conditions of possible experience in the data.

Suppose, for instance, it was affirmed as a result of medical statistics, that in
two-fifths of a number of cases of disease of a certain character, two symptoms, 2
and y, were observed ; in two-thirds of all the cases, the symptoms y and z were
observed ; and in four-fifths of all the cases, the symptoms 2 and y were observed ;
so that the number of cases observed being large, we might, on a future outbreak
of the disease, consider the fractions two-fifths, two-thirds, and four-fifths, as the
probabilities of recurrence of the particular combinations of the symptoms 4, y,
and z, observed. The above formulz would show that the evidence was contra-
dictory. For representing the respective fractions by p, g, and 7, the condition

p>=dqtr-l
is not satisfied.

It isan evident consequence of the principle enunciated in Art. 11, that in
determining the conditions of possible experience and of limitation, we may employ
any translated form of the problem, just as well as the form in which it is originally
expressed. Thus, if we take the translated form of the problem of that article,
and represent sleet by s, drift by ¢, storm by w, we shall have as the data

Prob. s=p, Prob. t= q, Prob. u=r
with the conditions
stu=0, uts=0, ust) : 5 : (7)
the queesitum being Prob. stw, which, as before, we shall represent by w.
Now if we write
Prob. stu=u, Prob. stu=0, Prob. s wt=0, Prob. sut=A
Prob. tus=0, Prob. tus=p, Prob. wst=y : : : (8)

608 PROFESSOR BOOLE ON THE COMBINATION

we have the following equations :—

Ut mA =p
U+P=q : : : ; : : (9)
Ut+tv=r
with the inequations
USO ASO, eS OVO = Sa ee | Se

Determining from the equations A, yu, y, and substituting in the inequations, we get
u>0 p—us0, g—us0, r—us0, ptgtr—-2u =1.. (1d)
a system which agrees with that obtained by the previous investigation (5) Art. 13.

14. The general rule for the determination of the conditions of possible expe-
rience and of limitation in a question of probability may be thus stated.

Resolve the events whose probabilities are either given or sought, into the
mutually exclusive alternatives which they involve. If the calculus of Logic is
employed, this is done by development.

Represent the probabilities of these alternations by A, py, v, &., and express
the probabilities given and sought by the corresponding sums of these quantities.
This will furnish a series of equations, which we will suppose to be 7 in number.

Determine from these equations any z of the quantities A, py, v, in terms of the
others.

Substitute the values thus obtained in the inequations

NEO Wiig peo ihe! BRS el sao (1)

A+M+Y.. = : ; ; : : Z ‘ (2)
Eliminate in succession such of the quantities A, p, v, . . as are left in the above
inequations after the substitution.

The elimination of any quantity as 7 from the inequations, is effected by re-
ducing each inequation to the form 7 = a, or to the form + = bd, and observing that
two such forms as the above give a = b.

If the “ alternations” into which the events whose probabilities are given or
sought are resolved, extend to all possible combinations of the simple events out
of which they are formed, the inequations (2), must be replaced by the equation

AtpPty.. =1 E : ; : d : (3)
The rest of the process will be the same as before.

In the form of the above method developed in the Philosophical Magazine the
quantities A, ys, vy, . . represent the probabilities, not of those alternations alone,
which are contained in the events whose probabilities are given or sought, but of all
possible alternations which can be formed, by combining the simple events 2, y, z . .
In this form, therefore, we have always an equation of the form (3), in the place
of an inequation of the form (2). But though the result is the same, the form.
given to the method in this section is to be preferred, as it requires the elimina-

OF TESTIMONIES OR JUDGMENTS. 609

tions of a smaller number of symbols, except when the condition referred to in
(3) is fulfilled, in which case, the methods are identical.

15. It remains to show how the conditions of possible experience as above
determined, restrict us in the choice of the hypothesis, by the aid of which the
final solution is to be obtained.

Taking for example the above problem of Art. 13, let us inquire whether it
would be lawful to assume x, y, and z as the primary simple events of the
problem.

If we make this assumption and then write

Prob.z=a Prob.y=G@ Prob. z=y
we find
Prob. zy=a@ Prob. yz=By Prob. za=ya

whence comparing with (1) Art. 13—

aB=p By=q Ya=r
solving which equations we have

a=/f B=/2 y=n/td . Prob. ayz=aby=V/pqr # ur)

Now, a, 6, y: being by assumption probabilities, and therefore, lying numerically
between the limits 0 and 1, we must have
qr <p p< PE ah ee fuse yl 4B

as the conditions to which p, qg, and 7 (beside being fractional) must be subject.
These conditions do not, however, agree with, and are not involved in, the condi-
tions of possible experience, determined in (6) Art. 13. We may conclude, there-
fore, that the hypothesis upon which our solution is founded, involves elements,
the introduction of which is unwarranted, and that the value of Prob. xyz deter-
mined is erroneous.

We may show, in fact, that the conditions (5) imply the conditions of possible
experience, and something more. If gr <p then, a fortiori, gr =p+(1—q) (1-7)
since (1—g) (1—r) is essentially positive. Therefore,

qr <ptl—q-rt+gr
whence p>qtr-l
which is one of the conditions (6) Art 13. In the same way the other conditions
in that article may be deduced from (5). The reverse reduction is, however,
impossible.

16. The hypothesis upon which the method developed in the Laws of Thought,
cap. xvii., for the solution of questions in the theory of probabilities whose elements
are logical, is founded, seems to be the only one which satisfies the requirement
referred to in Art. 12. It was not, however, upon such considerations as this,

VOL. XXI. PART Iv. 8B

610 PROFESSOR BOOLE ON THE COMBINATION

that the method was founded. As presented in the Laws of Thought, it rests
upon principles which, to my own mind, have something of an axiomatic character,
Viewed in this light, its perfect accordance with the requirement above explained
may be considered as a verification of it a posteriori. In itself, however, this
accordance affords a sufficient ground of confidence in the legitimacy of the hypo-
thesis. On the proof of this accordance I shall say something hereafter. At
present I will only state the hypothesis, and show in what the accordance
consists.

The hypothesis is the following :—Translating our problem by the aid of the
calculus of logic into a language in which the events whose probabilities are given,
appear as simple events subject to conditions founded on their definitions, Art.
11, we ascend above these simple events to another scheme of simple events,
which are free, and which, when actually subjected to the conditions to which
the before-mentioned simple events are necessarily subject, shall have the same
probabilities, and shall in every respect take their place. The unknown proba-
bilities of the free simple events, which form the elements of this hypothesis, must
be so determined as to render the substitution possible, and to permit a formal
construction of the problem, both in its data and by its queesitum, out of those
new elements.

The unknown probabilities being thus determined, the problem assumes a
form in which its elementary data are the probabilities of simple events unre-
stricted by any condition. In this form the solution of the problem is possible by
mere consequence of the fundamental definition of probability. The ground
upon which this hypothesis was presented in the Laws of Thought was its intrin-
sic reasonableness. On this point I will only refer to my observations in the
original work. The ground upon which, in the present essay, I wish to rest the
hypothesis is, that it is the only one which does not impose upon the data other
conditions than those of conformity with a possible experience. The conditions
which must be fulfilled in order that p,q’, &c., in the substituted and hypothetical
data, may be measures of probability at all,—z.e., may be positive proper frac-
tions,—are precisely the conditions of possible experience in the original data..
(See Appendix. )

17. The application of this hypothesis is so fully explained in the Laws of
Thought, cap. xvii., that I shall here only describe the general method for the so-
lution of questions in probabilities to which it leads, and show the connection
which exists between the several parts of that method and the foregoing doctrine.

General Method.
Representing the problem to be solved under the form—

Given Prob: ?, (#. 4% % + .)=p Prob. (a, y,2 . . )=¢, de!
Required Prob. (a, y, 2. +)

OF TESTIMONIES OR JUDGMENTS, 611

and expressing the unknown value of Prob. ») (2, y,z . . ) by #, we form the logical
equations :—
D>, Gaede 3) biGpe.aiesidas ts Ge;
iP tos
and hence, determining w as a developed logical function of s,¢ . . we havea

result of the form
0

eLALOBE Col aDind ho diuahe deuce qwult yey

Here A, B, C, D are logical combinations of the simple events, s, ¢, &c., and the
connection in which they stand to the event w and to each other is the following :
A expresses those combinations of s, 7, &c., which are entirely included in ,—2.e.,
which cannot happen without our being permitted to say that w happens. B re-
presents combinations which may happen, but are not included under w ; so that
when they happen, we may say that w does not happen. C represents those com-
binations, the happening of which leaves us in doubt whether w happens or not.
D, those combinations, the happening of which is wholly interdicted.

Thus far we have only translated our problem into a language in which its
data are the probabilities of simple events, viz. :— :

Prob. s=p Prob. t=q, &e. : : (2)
The condition, founded on definition, to which these simple ae are subject is,
D=0

or, which amounts to the same thing,

A+B+C=1
indicating that the combinations expressed by A, B, and C can alone happen. If
we represent A+B+C by V, we have

w=A+ s C : F 3 § if (3)
with the condition
V=1 bated (4)

Of these equations, the latter expresses the conditions to aac ie seal events,
s,t, &c., are subject; the former expresses w as a logical combination of those
events.

We now, in accordance with the hypothesis, ascend to a new scheme of simple
events, s, ¢, &c., unrestricted by any condition, and possessed of unknown proba-
bilities, 7,’ 7’, which are to be so determined that when s,’¢ . . are subjected to
the same condition (4) to which s,¢..are subject, they will have the same
probabilities as s,¢ . . The system of equations to which we are thus led, and
which contains the implicit solution of the problem, is the following (Laws of
Thought, cap. xvii., p. 267) -—

V; ae Vv; a A+C
ty a,
V, being formed by selecting those terms from V, which contain s as a factor; V

Ne eee

612 PROFESSOR BOOLE ON THE COMBINATION

those, which contain ¢ as a factor, &c.; and then regarding s, ¢, &c., as algebraic
quantities. From the system thus formed, we must determine w as a function of
p,q . . and the arbitrary constant c, should it be present. This will be the solu-
tion of the problem.

The quantities s,¢ . . are the same as p,q’ . . and represent the probabilities
of the hypothetical simple events, represented bys’, ¢ . . Accordingly, as pro-
babilities, they must admit of being determined as positive proper fractions, and
that the solution may not be ambiguous, they must admit of only one such de-
termination. These conditions will be fulfilled whensoever the problem represents
a possible experience, and it will be then only fulfilled. And in this way, or by
directly investigating the conditions of possibility by the rule of Art. 14, a solution
is made determinate.

The arbitrary constant ¢ does not, as has been intimated, always present itself.
When it does, it represents the unknown probability, that if the event C occur, w
will occur. It indicates, therefore, the new experience which would be necessary
in order to make the solution definite.

18. I will, for the sake of illustration, apply the method to the problem of
Art. 11, and in so doing I will limit the solution by the conditions relative to
Sih, OCC

The problem, as symbolically expressed in Art. 13, is as follows :—

Given Prob. zy=p Prob. yz=q Prob. zz=r } ; (1)
Required Prob. xyz
Translating the problem as directed in the first part of the rule, we write
“ys Z=t 7A iV)
' a } / ; . (2)
whence, by the calculus of logic,

1 mes +e: =
+9 (Stutsuttivs) : : : : (3)
Hence we find ini
Vestu+stut+tsutusttsty . : 2 : (4)
and are led to the algebraic system of equations
stu+stu _ stvt+tsu _ stut+ust
P q iad r
stu Sees ee ee ee
= ay = Slutstvttsutusitsiv . Bas hg (5)

These equations may be simplified by dividing every term by s tv, and then as-
suming

Soe s Ms U ae y - . ° > (6)
. 3 t 7)
They thus give
stots’ _ siv+t _ stv'tv'
P q

ie U f
— = stv+s +t 4+u4+l : : ‘ : (7)

OF TESTIMONIES OR JUDGMENTS. 613

The condition to which s‘7’v' are subject obviously is, that they shall be posi-
tive quantities, for this is equivalent to the condition that s, ¢, v shall be positive
fractions.

From (7) we readily find

U

s i ) stv’

= = fa qe He RG stuts+¢t+u'4+1 (8)
Whence
JUL gee os era
2u—p—q-rt+1
7 —uU
v= sm aap ore ENGR er ccgi (Oy
: r—U

CS = SS
2u—p—q—rt+1
Substitute these values in the equation

, ce s tv!

p-u 7

and reducing we get
(p—u) (¢>4) (r—W)—u (2a—p—g—Prb?” | vn, (10)
an equation for determining w.
And now let us inquire into the consequences which flow from the condition
that sz’ v’ are positive quantities.
In the first place, the last member of (8), and therefore each other member
of that system will be positive. This requires that the denominators, p—w, g—u,
r—u, and uw, should be positive, whence we have
re es my 0 aaa
Again, p—w, q—u, and r—u being positive, the common denominators, 2u—p—q—r
+1 in (9) must be positive, whence
mnt) edi Cie)

Such are the conditions relative to w. They agree in all respects with those as-
signed in the previous investigation, in (5), Art. 13; and, as in that article, the
elimination of w leads to the conditions of possible experience,

p>0 q>0 rs0

fess gtr—1

aT airy meetin lala aut (AB)

r> ptq-l
It may be well to notice, that these conditions involve the necessity of p, g, and 7
being fractional, though of course this does not exhaust their significance.

19. It remains to show that when the above conditions are satisfied, the
system (7) will admit of but one solution in positive values of s’, 7, v’, and that
(10) will furnish but one value of w satisfying the conditions (11) and (12).

Let us write 10 in the form

u(2u—p—g—r+1)?—(p—u) (q—u) (r=u)=0 «(14
VOL. XXI. PART IV. 8c

614 PROFESSOR BOOLE ON THE COMBINATION

or, for simplicity, in the form
U=0.

The lower limit of wis, by (11) and (12), either 0 or Se Sir according as

the latter quantity is positive or negative; the upper limit of w is the least of the

t pt+qtr-l
2

quantities p, g, 7; suppose it p. First, le be positive, then, making

u equal to this quantity, the value of U, as given in the first member of (14)
becomes negative. Again, let w=p, then U becomes positive. Thus, as w varies
ES panes

from 9 UP to p, U changes from negative to positive. Now
iY =(2 u—p—q—r+1)?+4u(2u—p—q —rt+1)+(p—u) (q—u)+ (q—v) (r—u)+ (7-4)

(p—u) ; : : ; : (15)
which within the supposed limits is always positive. Hence U varies by continu-
ous increase, and once only in its variation becomes equal to 0.

Secondly, let a be negative, then w, varying from 0 up to p, U as

before will vary by continuous increase from a negative to a positive value. See
the first member of (14). Whence U, changing by continuous increase from a
negative to a positive value, will still only once become equal to 0.

Wherefore, in either case, one root only of (10) will lie within the limits as-
signed to win (11) and (12). And this one value substituted in (9) will give one
set of values for s’, ¢, v’.

20. The solutions which we have now obtained of the same problem on dif-
ferent hypotheses with respect to the selection of the simple events, set in clear
light the principles upon which the due selection of such hypotheses depends.
The hypothesis which seems most readily to present itself utterly fails, while
the other, based quite as much upon an apparently remote speculation on lan-
guage, as upon the study of the laws of expectation as usually conceived, finds a
support and confirmation within the realm of pure mathematics which is of the
most remarkable kind.

21. A practical simplification of the general method is suggested by that step
of the preceding solution, which reduces (5) to the form (7). If we remove the
traces (’) from the letters in the latter system (and they do not at all affect the
solution), we obtain what (5) would become if we replaced each of the symbols
s, t,v, by unity. Practically, therefore, we may modify the general rule in the
following manner :—Having obtained V, replace each of the symbols s, i, &c., by
unity, and proceed with the reduced value of V just as before, 7.¢. let V,
represent that portion of V of which s is a factor, &c., then form the system of
equations
Vie cule pA +60.
Siig ae Soa ie

Ve aiholhoi tak (0 soi aii)

OF TESTIMONIES OR JUDGMENTS. 615

and hence determine w as a function of p, g..andc. The conditions of possible
experience and of limitation will be found by supposing s, é, to admit of a single
determination in positive values. Or as before, they may be found indepen-
dently, and then applied to limit the solution.

22. We now proceed to the consideration of the problems referred to in Art.
(1.) We shall first examine the problem which has for its object the determina-
tion of the most probable measure of a physical magnitude, two conflicting mea-
sures of which have been assigned by observation. The problem is not, as has
been said, Art. 2, in its immediate presentation, one whose elements are logi-
cal, but it admits, as we shall see, of being so represented as to give it this cha-
racter.

PROBLEM 1.

Two simultaneous observations of a physical magnitude, as the elevation of a star,
assign to it the respective values p, and p,. The probability, when the first observa-
tion has been made, that it is correct, is c,, the corresponding probability for the
second observation is c,. Required the most probable value of the physical magni-
tude hence resulting.

Kirst Solution.

23. The numerical elements which are not, in their immediate presentation,
probabilities, are p, and p,. But these become such if we contemplate the pro-
blem under another aspect. Let a quadrant be taken as the unit of magnitude,
then p, and p, are proper fractions ; p, actually expressing the probability af-
forded by the first observation, p, that afforded by the second observation, that a
pointer, directed at random to that quadrant of elevation in which the star, re-
- garded as a physical point, is situated, will point below the star. The problem
thus regarded contains the following logical elements, which we shall express by
appropriate symbols, viz.

The event which consists in the first observation, such as it is, being made =w.

The event which consists in the second observation, such as it is, being
made =y.

The event which consists in the first observation being correct, =7v.

The event which consists in the second observation being correct, =v.

The event which consists in a pointer, directed at random to the quadrant in
which the star is situated, pointing below that star, =z. |

We must now express symbolically the data, including therein whatever logi-
cal connections we can establish amorg the events, x, y, 7, v, and z.

The probability that the first observation, when made, is correct, is ¢. This is
a conditional probability ; or, to adopt a well-known form of expression, it is a
probability a posteriori. Viewed from a point of time anterior to the observa-

616 PROFESSOR BOOLE ON THE COMBINATION

tion, it is the probability that if the observation be made under its actual circum-
stances of care, personal fitness,’ instrumental accuracy, &c., it will be absolutely
correct. Symbolically, it is the probability that if the event « take place, the
event # will take place. The only mode of expressing this is by writing for the
Pee of x an arbitrary constant a, we have then

Prob. z=a, Prop. gw =a, €;)\'s L ; (1)

The events x and w are not, however, independent. If we can affirm that a
given observation is correct, we can affirm that that observation has been made.
Symbolically, the occurrence of the event w implies the occurrence of the event
x. Expressing this proposition in the language of the calculus of Logic we have
the equation.

WO ee 5 : : 3 (2)
This forms a part of our data. It permits us to change also the form of one
of the previous data, and instead of (1) to substitute
Prob. =a, Prob. w=a, ¢, : : 4 (3)
In like manner, representing the arbitrary probability of the event y by a.,,
we have

Prob. y=a, Prob. yu=a, ¢, : : ; (4)
With the connecting condition
vy=0 : 2 : : (5)
which would permit us to substitute for (4) the system
Prob. y=a, Prob. v=a, ¢, : : : (6)

Again, when it is known that the first observation is a correct one, the proba-
bility that an indicator directed at random to the quadrant in which the star is
situated will point below the star is p,. This, too, is a conditional probability.
Symbolically, it is the probability that if the event w occur, the event z will
occur. Hence, as the probability of the occurrence of w as a, ¢,, we have

Prob. wz=a@, ¢, py - (7)

In like manner we find

Prob. uZ=, Cy Pp (8)

Lastly, it is supposed that the values p and q are different. This involves the
condition that the observations cannot both be correct. Whence we have the logi-
cal equation. .

w v=0 ; : : ; e (9)

This completes the analysis of the logical elements involved in the data of the
problem. We now proceed to analyse those involved in its quesitum or object
proposed.

That object is to determine the probability of the event z, when the occurrence

OF TESTIMONIES OR JUDGMENTS. 617

of the events w and y is known. Symbolically expressed, it is the value of the
fraction.
Prob. x y z
Prob. x y
or, as it may, by resolving the denominator, be written,
Prob. x y z
Prob. zy z+Prob. ayz Ay laste Hi Uti Bb eat ies
To effect this ohject, we shall determine the value of Prob. xyz and Prob. «yz
separately.
Collecting the elements furnished by the preceding analysis, the first of the
partial problems herein involved may be thus stated :—

Given Prob. 2=a, Prob. y=a,
Prob. w=a,¢, Prob. v—@,¢. ' di)
Prob. wz=a,¢,p, — Prob. vz=da,c,p,
with the conditions, ww=0, wvwy=0, wv=0, ice co i> GED

Required w, the value of Prob. xyz.

In selecting the above, I have chosen to employ (3) in place of (1), and (6) in
place of (4). It makes no difference in the final result.

In accordance with the rule, let us write

we—s, w=t, cyz—=) ; : ‘ (13)

we must then from (12) and (13) determine ¢ as a developed logical function of x,
Y, 2, 0,8, and t.

This problem admits of perfectly definite solution on the principles of the cal-
culus of Logic. Ishall here merely give the result, and point out a method by
which it may be independently verified. We find

+ oe ywus t+ terms whose coefficient is = eaten syd AS

We may verify this expansion by substituting for s and ¢ their values wz and
vz, paying attention to the conditions (12), and then comparing the result with
the value of @, Viz., yz.

Thus the term xy wsvét becomes, on substitution

aywuxwex(l—-vz)=ayzwy
by the calculus of Logic. Now this represents a class entirely included in the
class xyz, whence the coefficient of the term is unity.

The term zw wsyv ¢ reduces to x w zy v, and represents a class no part of which
is included in wyz, whence the coefficient is 0.

VOL. XXI. PART IV. 8D

618 PROFESSOR BOOLE ON THE COMBINATION

The term xywvs t, reduces to xywv, and represents a class some part of
which is included, and some part not included under the class xyz, whence the

coefficient zu ; for an event included under the former class may or may not be

included under the latter.

Lastly, any term whose coefficient in the expansion is 2 would, on effecting

the above-named substitutions, become 0, indicating the absolute non-existence of
the class which it represents.
Resuming the value of ¢, and adopting the simplification of Art. 21, we find
for V the value
V=aywst+ayut+aows+yut+e+y+l+aywt+aw+ cyvtyv+ay
=(@+1) (y+1)+yu(e@4+1) (€+1)+aw(y+1)(s+1) . : (15)
And hence we have the following system of algebraic equations:

aytl)+ayut+1)tawy+) (s+) _ yeti+yv@tt) (¢+1)+ewy(s+1)
a a

1 2

_ rw(y +1) (s+ 1) _ yet 1)(¢+1) _ vwytljs _ yo(w+))t
eT Dy Cy AaPy MH, Co Po

_ vyws + xyvt + cxy

= =(¢@+1)(y+1)+yu(@ +1) (+1) + aw(y4+1) (s +1) | (16)

From these equations, if we assume
(v@+1)(yt+1)+yu(e@4+]) (+1) + aw(y+1)(s+ D=A,
r being a subsidiary quantity introduced for convenience, we readily deduce
pee +axyut+ cay

(17)
wcws(yt+l
TA a g
= Gaye +1) house +1)
1 _(@+1) (y+) +aw(y +1) (s+1)
—Ay C,= eT Te ae
@, CP, Xa (1—¢,) _ zyws
Hence ares = -\ Sead Weel 5)
In like manner
Az CPx (l1—c,) _ xyut
1—a,¢, we DT ; : : : : (19)
Again we have
a(y+1)+ayv(t+1
a,(1—¢,)= (y+1) — ( )

a,(1—c,) _y(ert 1) oe +1)

OF TESTIMONIES OR JUDGMENTS. 619
1—a,¢,—a,¢,=

(v7+1) (y+1)
A

l—a, yes ale

fie ¢, thos) (y +1) sted a (s+1)
Whence we find
a, (1—¢,)a,(1-ey) (L-a, ¢,—- 4, ¢) _ wy (20)
(1—a,¢,) (1-4, ¢,) A
By means of (18), (19), and (20), we reduce (17) to the form
we) UO Py t aoe Uy Cy Pa + ea a ea ae.

therefore effecting a slight reduction
eae { ; et C Pith ae Copy + C(1—a, ¢, — a2 Cp) } (21)
The arbitrary constant c, interpreted according to the rule, is the probability
that if the event xyw v s ¢ take place, xyz will take place. Putting for s and ¢
their values, and reducing as before, we find that c is the probability that if vywv_
take place, wyz will take place. In the end this amounts to the following state-
ment.
¢ = probability that if both observations are incorrect, a pointer directed at
random to the quadrant in which the star is situated will point below the star.
The value of Prob. xyz will be obtained from that of Prob. «yz by changing
Pp, p, and ¢ into 1—p,, 1—p,, and 1—c. If we effect this change, and then substi-
tute the expressions above found, in the formula,

Prob. xyz=

EvOUS OYe ‘ee betes
Prob. xyz+ Prob. xyz
We shall find
l—a,c l—a,ec
Prob. xyz Pe rat pace a OG)
EY ie ee ON eS eA,
aL antl tal (es T
Prob. wy a 6, + ae Me ¢, +1—a, ¢,—4, ¢,
(22)
l—a,¢, l—a,¢,
= Cp, + =e CP, +c(1—a,c,—a, Cy)
l—a, l—a,
1+ canes + Te,

This expression involves an arbitrary constant c which we have no means of
determining. This circumstance indicates that those principles of probability
which relate to the combination of events do not alone suffice to enable us to com-
bine into a definite result the conflicting measures of an astronomical observation.

The arbitrary character of the final solution might have been inferred from

620 PROFESSOR BOOLE ON THE COMBINATION

the appearance of the symbol : in (14). Ihave thought it better to complete

the investigation, especially as it will serve as a model for the one which follows.

24. Before proceeding to the second solution of the problem, I will endeavour
to explain the principle on which it will be founded. It is involved in the fol-
lowing definition.

Definition. The mean strength of any probabilities of an event which are
founded upon different judgments or observations is to be measured by that sup-
posed probability of the event @ priorz which those judgments or observations fol-
lowing thereupon would not tend to alter.

Thus, suppose we were considering the question of the suitableness of a newly
discovered island for the growth of a particular plant, and that the probability
of its suitableness, as dependent upon general impressions of the climate were 7;
but that added special observations,—such as analysis of the soil, determination of
allied species growing in the locality, &c., had some of them the effect of raising,
others that of depressing, the general expectation before entertained. Now we
might suppose that expectation to have had such a measure, that the added obser-
vations should, when united, leave the mind in the same state as before. I call
that measure the mean value of the testimonies—the value about which, to adopt
(for illustration, not for argument) a mechanical analogy, they balance each other.
I conceive that in thus doing, I am only giving a scientific meaning to a term which
has been hitherto used in a vague sense. I shall show that the formula of the arith-
metical mean is a special determination applicable only to particular problems, of
the more general mean of which I here speak, and that other determinations of
it exist, applicable to other problems, but possessing, in common, certain definite
characteristics.

To apply this principle to the problem under consideration, we must add to
the data a new element, viz., the @ priori value of Prob. z, 7.e., the value which
the mind is supposed to attach to it before the evidence furnished by the obser-
vations. We will suppose this value 7. We must then seek, as before, the @ pos-
teriori value of Prob. z, 2.e., its value after the observations, and, equating the two
expressions, determine thence the value of r.

I shall, in referring to the above principle, speak of it as the “ principle of the
mean.”

Special solution of Problem I. founded upon the principle of the mean.
Assigning to z the a priori probability 7, our data are the following:

Prob. x=a, Prob. y=a, Prob. 2=r
Prob. w=a, ¢, Probs y=a5i¢;
Prob. wz=a, ¢, DP, Prob. vz=@y Cy Po:

with the conditions wx=0 vy =0 wu=0

OF TESTIMONIES OR JUDGMENTS. 621

and hence we are to seek, as before, the value of

Prob. xyz 4 (1)
Prob. xyz+ Prob. xyz
Assuming then as before,
wz=Ss, va=t, xLyi=P
we find, by the calculus of Logic, the following expression for ¢ as a developed
logical function of x, y, w, v, s, ¢, and z, Viz.:

—xywszvtt+xyvtizw stauyzwust
y y Y

+Ofeyuwstzt+yvataws +yvaws ztt+aywszvt+awesyut

+ terms with coefficient : icles py ena teaeiae gat 1)

Hence, adopting the simplification of Art. 21, we have
V=xywse + vyvta + vyet+ ayy + yuu + yu + vyw + ewes
+ewtaytactyz+atytetl
=aw(y +1) (28 +1) +yu(@ +1) (26 +1) 4+ (e+) (y+) &+)) : (3)
whence we form the algebraic system
aw(y +1) (zs +1) + ayu(2t +1) +2(y +1) (+1)

at

_ awy(2s +1) + yv(a+1) (+1) +(@+)Dyet))
ay

_avw(ytl) stl) _ yo(e +1) @t+))

+ i) a Dy Co

_au(yt jes — yu(a+A)at

yy Py A, Co Po

_ vwlyt+l)est+ yu(a+1)2t+ (@ +1) (yt lz
r

_ vyews + vyzut + xyZ

ig U

—vwly +1) (+1) +yu(@ +1) +1) + (t+) Yt) @4+1)_4 (4)
J a

A being a subsidiary quantity introduced for convenience.
From the above we find

apa; Ge bealeaitstl) ee (2+1)
: awes(y +1
is ep, =a

eatin _avw(y +1) (@s+1)+(@+1) yt 1D @+))
aah. at a bot. ee

VOL. XXI. PART IV. SE

622 PROFESSOR BOOLE ON THE COMBINATION

whence
a,(l—e¢ LYZWS
fz a, ap, =“ - ©
In like manner we find
a, (1-— vyzut
cana BD a, 042,= oi Sh? on eee as (6)
Again, since we have faa the above
Gee Tt Eig. %,
l—a,c, yt+l1 = I-a,c, #+1
we have
a, (1—e¢,) a, (l—c,) - ay
(l—a, ¢,) d-a, ¢) ~~ (@+1) (y+1)
moreover,

e+1 +1
r—, Cy Py— Ay, ep, et Ds

Multiplying the two last equations together we find

aac Gael OTmiPin mara 6. ®)

LYZWS + vYZVE+ LYZ
Now, = TAT ae y

Substituting in this expression the values found for its several terms in (5), (6),
and (7), we have

_% (1—¢,) a,(1—¢,) a, (1—<¢,) a,(1—¢,) es ii

nik ae Sania: ws A, Cy Po (1—a, ¢,) —a, ¢,) (7a, ¢, Py — 4 Cy Pe)
This is the value of Prob. xyz. That of Prob. zyz will be found by simply changing
in the above expression p,, p., and r, into 1—p,, 1—p,, and 1—r respectively. These
expressions admit of some reductions, and give

_a, (1—e¢,) a, A—c,) {== La,
Prob. zyz= Gwe da, «2 ase, Cy ey grea LP } : : (8)

a, (1—e¢,) a, (1—c,) (ao 2 1-a, z Ni
(l—a, ¢,) d—a,¢,) Ll—-«, G CRB) +e, ¢,(1—p,) +1—r - (9)
whence we find for the @ posteriori value of Prob. z,

1l—a, i-a
Prob. vyz _1—e, peels 1— a a
Prob. xy 1— —a, 1—

Te cha as ar “26,41

Prob. vyz=

Equating this to 7 we have

ey ik =(—* l—a,
mee, Py t+ ea Inet agetl)r
Whence
1l—a, 1—
ane C, Py + Tae Ps
Ce Sm ar)
ete: ala

OF TESTIMONIES OR JUDGMENTS. 623

26. Such is the final general expression for the probable altitude of the star.
The following observations may throw light upon its real nature :—

1st, In the analysis by which this expression was obtained, p, and p, are the
observed altitudes of the star, a quadrant of the celestial arc being taken as
unity. Considered, however, as the expression, not of a probability, but of the
most probable measure of a physical magnitude, the truth of the formula will of
course be independent of the unit of magnitude.

2dly, The formula is independent of mechanical analogy. We may place it in
the well-known form

r= Ws.p, + W, Dy : ; (1)

in which, as the maint i is usually treated W, and W, are called the fener of the
observations. Here, however, these quantities are determined as functions of the
initial data—these data being probabilities. We have

1l-a, l—a,
Ww I—e,"! I—e,” 9
“Toa, , ea, i= ima, a Po
Le tide, 2 Deca, batt Be ays

3dly, The initial probabilities, of which W, and W, are functions, are neither
foreign nor imaginary elements. They may be difficult to determine, but theo-
retically their determination rests upon considerations which are entirely proper
to the subject. When an observation has been made, the question whether
it is correct or not is a question of probability. Wecan never predicate absolute
correctness. We can seldom affirm absolutely that an observation is incorrect.
Our knowledge of the circumstances of the observation, Art. 22, leads us to regard
the probability in question as sometimes greater, sometimes less. To suppose it
capable of a numerical value, as we have done, by the introduction of the con-
stants ¢, ¢,, is then perfectly legitimate. It has been said that an estimate of the
correctness of the observation rests upon the circumstances by which it was ac-
companied. These circumstances, taken in the aggregate, are themselves a sub-
ject of probability. This we express by the introduction of the constants a, a,.
The probability after an observation is made that it is correct, and the probability
before it is made that the state of things shall be such as to give to the result that
particular probability of correctness, are quite different things.

Athly, In the same course of observations made by the same individual with
consciously uniform regard to personal and instrumental accuracy the values of
a, and a, would be sensibly equal. The formula (10) would thus reduce to the
following, viz. :—

pisntposp
pesca bce St Re eae ee (3)
Ce
Ie,

624 PROFESSOR BOOLE ON THE COMBINATION

Cy Cy
1— i
Here 9 W, 222 le 2 og iwi eee redo 2qrraing
ere + Cy Cy ze Cy
1—c¢, 1l—c, 1l—c, 1l—c,
If c,=1, we have
Wes Wi=0
and r=DP,-

This accords with the condition that if either of the observations is believed to
be correct, the value which it furnishes for the altitude of the star must be taken
as the true one.

5thly, If c,=c,, 1.¢., if we have no right to give preference to one observation
over the other, we have

ra iP tS See Cae

the formula of the arithmetical mean.

6thly, From the form of W,, W, in (4), it is evident that the weights, so to
speak, of the observations vary in a higher ratio than that of the simple proba-
bilities of correctness of the observations. The practical lesson to be drawn from
this is, that we ought to attach a greater weight to good observations, and a
smaller to bad ones, than, according to usual modes of consideration, we should
be disposed to do.

The above are the most important observations suggested by the formula
to which the last investigation has led. One or two remarks remain to be offered
upon the analysis by which it was obtained.

Although the two forms of investigation which we have exhibited differ, there
is nothing inconsistent in the results to which they lead. If we compare corre-
sponding formulze in the two, ¢.g., the values of Prob. «yz, or those of Prob. xyz,
we shall find that the one investigation assigns a definite but consistent value to
what the other left arbitrary. Either comparison gives
MR Memes ay em AY

1l—a, ¢,—4, ¢
We may prove, either by the “ conditions of possible experience,” or independently,
that this value is necessarily a proper positive fraction, and this accords with
the interpretation of c as a probability. Art. 23.

27. But a much more important consideration is the following. It is a plain
consequence of the logical theory of probabilities, that the state of expectation
which accompanies entire ignorance of an event is properly represented, not by

c

the fraction : but by the indefinite form = And this agrees with a conclusion

at which Bishop TErRoT, on independent, but as I think just grounds, has arrived.*
Now this shows, why, if the consideration of the a priori probability of z is, from
* Transactions of the Royal Society of Edinburgh, vol. xxi. p. 375.

OF TESTIMONIES OR JUDGMENTS. 625

the insufficiency of the remaining data, necessary in order to give to the a poste-
riort probability of ~ a definite value, the solution obtained when that @ priori

value is neglected should involve the symbol 9. The presence of this symbol in
sg 0 ui

a solution always indicates insufficiency in the data. And herein, as it seems to
me, consists the reason why the mind, impatient of incertitude even while dealing
with the very science of uncertain knowledge, is led to seek escape from its doubts,
by calling in the aid, in some form or another, of that adventitious principle which
I have denominated the principle of the mean. I say in some form or another;
for I can conceive of another form of the same principle connected more directly
with the idea of a /imit than with that of amean. Thus as testimonies which
are insufficient of themselves to produce a definite expectation may definitely
modify a definite expectation previously formed, we have suggested to us the idea
of that limiting state to which perpetual and independent repetition of the same
series of testimonies would cause the mind, whatever its starting point of expec-
tation might be, to tend. And as this limiting state would be one which a further
repetition would not alter, we should thus arrive in effect at the same solution
as is indicated by the principle of the mean, in its direct expression.

28. I have extended the preceding analysis to the case in which three obser-
vations are to be combined, a case which, in connection with the previous one, is
sufficient to determine the general law. The result is what the preceding analysis
suggests, and may be expressed in the following theorem :—

If 2 conflicting observations assign to the altitude of a star the respective
values p, 7... P,; if, moreover, @,a@,..a@, are the antecedent probabilities that
the observations will be such as they prove to be with respect to those circum-
stances which determine their relative accuracy, and ¢,c,..c, their respective
probabilities of correctness to a mind acquainted with these circumstances, 2.¢., to
the mind of the observer after the observations have been made, then the most
probable altitude of the star will be

1-a,, $ 1—a,, 4 l-a,
ee a ee 2 eee
l—a, l—a, l—a,
ete; ¢, + ima .e + tae,

This expression admits of the same deductions as the one before obtained for
the case in which the observations are two in number, and in particular it leads,
when the circumstances of the observations are judged to be in all respects the
same, to the principle of the arithmetical mean expressed by the formula

n

29. I have remarked that the principle of the arithmetical mean has some
VOL. XXI. PART IV. 8 F

626 PROFESSOR BOOLE ON THE COMBINATION

claim to be regarded as axiomatic. In the preceding sections it presents itself
as a special result of a very complex analysis founded upon the logical theory of
probabilities. Now I wish to observe, that there is nothing in these circumstances
which we have a right to regard as denoting inconsistency. Of the theory of
probabilities it is eminently true that modes of investigation, which to our pre-
sent conceptions must appear fundamentally different, habitually lead us to the
same result. A profounder acquaintance with the laws of the human mind, and
a deeper insight into the relations of things, might perhaps show us that prin-
ciples which appear to us to have nothing in common may yet have a necessary
connection with each other,—may possibly spring up from a common origin. I
will endeavour to make my meaning clear by two illustrations, which will pre-
sent this question in somewhat different lights.

30. An idea which seems naturally to suggest itself in connection with the
theory of probabilities is that of mechanical analogy. Evidence of this we see
in the language, already referred to, which attributes weight to observation. The
complete and scientific development of the idea will be found in a memoir by Pro-
fessor Donx1n,* who, establishing a kind of metaphysical statics on proofs of the
same nature as those which are employed in deducing @ priori the laws of ordi-
nary statics, has arrived, by legitimate deduction, at the remotest consequences
of Gauss’s theory of the combination of observations. The mind, in the developed
analogy, is compared to a lever acted upon by different weights, or to a mecha-
nical system subject to given forces, and seeking, under this action, a position of
equilibrium. Now it is at least a very remarkable circumstance, that an analogy
of this kind should not only admit of exact scientific expression, but should,
through a long train of analytical consequences, present the same laws and re-
sults, and suggest the same methods, as the principle of the arithmetical mean
already referred to. All the abstract terms by which mental states and emotions
are expressed, derive, if philology be of any value, their origin from outward and
material things. And hence, though it might be impossible to ascend historically
to the first employment of those expressions which describe the mind under the
action of forces, and speak of the balancing of opinions, we cannot doubt that a
perceived analogy was their source. But it could hardly have been anticipated
that this analogy should remain complete and unimpaired through so lengthened
a range of scientific deductions.

To what I have said above I will only add, that it is as instruments of ex-
pression and communication, rather than of thought, that material symbols,
and the analogies which they furnish, seem to me to possess importance.
Even the analogy which we have been considering cannot of itself occupy the
place of a first principle, but seems to be a particular manifestation of that deeper

* Sur la Theorie de la Combinaison des Observations. LiouvitLE’s Journal de Mathema-
tiques, tom, xv., 1850.

OF TESTIMONIES OR JUDGMENTS. 627

truth of which Lerpnitrz had a glimpse when he spoke of the principle of fitness
and congruity—“ principe de la convenance,”*—the ground of rational mechanics.
Of course, I do not contemplate this or any subjective principle whatever, as
affording us the slightest ground for affirming that the constitution of nature
must, @ priori, possess such and such a character. But it does seem to be a fact
that the material system has been constituted in a certain degree of accordance
with our rational faculties. The study of this accordance, @ posteriori, is a per-
fectly legitimate object; and I think it the more interesting, when it brings be-
fore our view the scientific form of any of those analogies which commended them-
selves to the minds of the fathers of our race, which are embodied in our common
speech, and without which we could apparently never hold converse with our
fellows, except upon material objects.

31. The second illustration which I have to offer is the following. Many of
the most important applications of the theory of probabilities, the method of least
squares, for example, rest upon what has been termed the law of facility of error.
This consists in the position, that in seeking to determine by observation a phy-
sical magnitude, as the elevation of a star, the probability that any measure will.
deviate by a quantity x from the true value, will vary directly as the function
«~”# where / is a constant quantity. The probability that our measure will
fall between the limits w and «+d being expressed by the function

k

Wat Bia ode

(1)
Gauss has shown that this is the only “ law of facility” consistent with the
assumption that, in a series of observations of the same magnitude, the arithmeti-
cal mean of the several measures obtained is the most probable value. It may
even be shown, that whatever the actual “law of facility,” under given circum-
stances, may be, and it is plain that it must vary with circumstances, such as
the constitution of the instrument and the character of the observer, &c., the
probability that the arithmetical mean of a very large number of values deter-
mined by observation will deviate from some fixed value by a quantity 2, will
vary directly as e~*”, & being a constant dependent upon the nature of the ob-
servations.+ Such, at least, is the limiting form of the function to which the law
of deviation approaches as the number of obervations is increased. Now it is
remarkable that considerations of a totally different kind, and founded mainly
upon our conceptions of space, lead to a similar result. The probability of linear
deviation (measured in a given direction) of a ball from a mark at which it is
aimed, seems to obey the same law; the principle upon which that law is deter-
* Erpmann’s Edit., p. 716.

+ For some very interesting illustrations of this doctrine, see the letters of M. Bravats, published
in the notes to QurTELET’s Letters on the Theory of Probabilities.

628 PROFESSOR BOOLE ON THE COMBINATION

mined being, not that of the arithmetical mean, but rather a principle of geome-
trical consistency, intimately connected with our ideas of the composition of
motion.

The principle was first stated in a popular and somewhat inexact form, by Sir
Joun Herrscuet, I believe, in the Edinburgh Review.* It was afterwards made
the subject of an adverse criticism in the Philosophical Magazine, by Mr Lrsiiz
Exuis.t There is no living mathematician for whose intellectual character I
entertain a more sincere respect than I do for that of Mr Exuis; and even while
stating the grounds upon which I differ from him, with respect to the value of
Sir Joun HERscuHEL’s principle, I avail myself of his labours, in giving to that
principle a more scientific form and expression, and in developing its consequences.
The language adopted in the following statement, will be, as far as possible, that
of the author of the principle,—the analysis will be that of Mr Ex.is.

Suppose a ball dropped from a given height, with the intention that it shall
fall on a given mark. Now, taking the mark as the origin of two rectangular
axes, let it be assumed, that the actual deviation observed is a compound event,
of which the two components are the corresponding deviations measured along
the rectangular axes. Grant, also, that the latter deviations are independent
events. Further, let us represent by f(z”), f(y’), the probabilities of the respective
component deviations measured along the axes x and y,—we give to them this
form, because, positive and negative deviations being equally probable, the func-
tion expressing probability must be an even one, 7.¢., must not change sign with
the error. Hence the probability of the actual deviations observed will be f(a’)
f(y’). Let it be observed that this is not the probability of a deviation to the
extent /x?+y? from the mark, but of a deviation to that extent in a particular
line of direction. Now, let the principle be assumed, that this expression is inde-
pendent of the position of the axes, 7.¢., that we may regard component deviations
along any two rectangular axes as independent events, by the composition of
which the actual deviation is produced. We have then w and y’ representing
two new component deviations,

TOE GF ey ee (2)
If y=V7a? +7? then w=0 and we have
eCAY Ca BONA ant) ren ere (3)

An equation of which the complete solution is,
ne) = Her
A and / being constants. The condition that the probability of the error must
* Vol. xci. p. 17, Art. QuETELET on Probabilities,

t Vol. xxxvii. p. 321, “‘ Letter addressed to J. D. Fores, Esq., Professor of Natural Philosophy
in the University of Edinburgh, on an alleged proof of the Method of Least Squares.”

OF TESTIMONIES OR JUDGMENTS. 629

diminish as the amount of the error increases, requires that / should be negative.
We may therefore write,—Z’, for h. Whence —
f(@)=Ae** ~ 9 )

To apply this result to the case in which the ball is ‘cineca at some point
on the plane which, projected on the axis of «, will fall between w and «+d, we
must give to A the form Cd.

Thus we get the expression,

Ce-** Oe

Lastly, the certainty that the ball must fall at some point for which the value

of x lies between —o and o gives us the equation

he Ce~* Ov=1

whence os =1 and C= Te Thus, the probability of a deviation from the axis

y to a distance lying between x and «+02 will be given by the formula
k 2 yt
a COT re ; ; (5)
an expression which agrees with (1).
In like manner, the probability that the ball will deviate to a distance greater
then y and less then y+ dy from the axis x will be
k 2,2
pe Se eal
Jae
whence the probability that it will actually fall upon the elementary area 0 x Oy
will be
2
POH Bar dy
Now, this result admits of a remarkable confirmation. For it is manifest that »
the probability that the ball will fall somewhere between the distances # and
2+0- from the axis y, ought to be equal to the above expression integrated with
respect to y between the limits—c anda. But that probability has been already

5 k -
determined to be Te e—** Ox; we ought therefore to have

i (Fee ae) dy= MED e L } (6)

an equation which is actually true.

Mr E tis considers this as showing, that the principle from which the demon-
stration sets out, viz., that the actual deviation of the ball from the mark may be
regarded as a compound event, of which the two independent components are the
deviations from the axes, involves either a mistake or a petitio principii. But
consistency of results can never be a proof of mistake in the principles from which
they are deduced ; and alone, it offers no adequate ground for the suspicion of a

VOL. XXI. PART IV. 8G

630 PROFESSOR BOOLE ON THE COMBINATION

petitio principit. It is to be observed, that it is only the probability of deviation
from a fixed axis which follows, according to the above investigation, the law
expressed by Gauss’s function. The probability of deviation in any direction to a
distance between 7 and r+0, from the mark, is expressed by a different function.
This would be fatal to any hypothesis which should represent Gauss’s function as
determining, @ priori, the actual law of deviation. There are indeed few cases in
which it can be determined what the law is, and writers on probability have been
far too anxious to interpret nature in accordance with their formule. No one
has shown this more clearly than Mr Exxis. The precise value of Sir Joun HeEr-
SCHEL’s principle, as corrected by him, I conceive to be this,—that it establishes
an identity between the law of facility of error expressed by Gauss’s function and
the law which in a special problem, involving the consideration of space and
motion, seems to accord with our most elementary conceptions of these things;
and this identity I apprehend to be, not an accidental thing, but a very distinct
expression of that harmonious relation which binds together the different spheres
of thought and existence.

33. We proceed next to the consideration of the second general problem,—that in
which it is proposed to determine the combined force of two testimonies or judg-
ments in support of a fact, the strength of each separate testimony being given.

The problem has a material as well as a formal aspect. Thus oral testimonies
differ from the judgments which are furnished by the immediate personal obser-
vation of facts. And although no definite general laws have, so far as I am
aware, been assigned concerning the mode in which the material character of
the evidence affects expectation, it is not to be doubted that an influence does
proceed from this source. As respects testimony alone, there are cases in which
we feel that it is cumulative,—there are cases in which we feel that it is not
so; and this difference we also feel depends upon the nature of the testimony
itself. But in the majority of cases, we should probably feel that the elements
upon which this difference of character depends are blended together, some
decided preponderance being due to the one or to the other. Testimony will
be chiefly or entirely cumulative which is given quite independently by different
persons, and is at the same time based upon different grounds. In proportion
as these conditions fail of being satisfied, the testimony partakes less and less
of the cumulative character. Still this possession of cumulative character may
be regarded as the standard by which the distinctive qualities of testimonies, as
affecting belief or expectation, may be estimated. In judgments founded upon the
personal observation of facts, though this character may be observed, the standard
seems to be different. When different modes of considering a subject—different
courses of experiment or inquiry—lead to different probabilities of a fact, some
making it more probable, some less, we generally feel that a kind of mean ought
to be taken among them. Perhaps the most succinct general statement would be,

OF TESTIMONIES OR JUDGMENTS. 631

that it belongs to testimony, in its normal character, to be cumulative,—to judgment,
to require the application, in some form or other, of the principle of means or
averages ; but that all departures from these normal states involve the blending of
the two elements together, in proportions determined by the degree of the de-
flection.

Now, although it does not belong to the theory of probabilities, in its formal
and scientific character, to pronounce upon the material character of a pro-
blem, and to say whether its data are in their own nature cumulative or not, yet
the results to which the theory leads are, in a very remarkable degree, accordant
with the distinctions which have just been pointed out. I shall show that the
solution of the problem of the combination of testimonies, when the data are
presented in a purely formal character, and without any adventitious principle,
involves arbitrary constants, and is therefore indefinite,—being capable, however,
under certain circumstances, of assuming a definite form. I shall show that
such a form is. assumed when the circumstances are such as to give to the testi-
monies the highest degree of cumulative character. I shall then solve the pro-
blem a second time, introducing that adventitious principle which I have already
exemplified in the problem of the reduction of astronomical observations, and
which appears to me to contain the true theory of means or averages. The form
of the solution thus obtained, which is also perfectly definite, will apply to the
case, in which it is our object, not to combine testimonies, in the ordinary sense
of the term, but to determine the mean of expectations founded upon the issues
of conflicting judgments. To one point of importance I must again, before enter-
ing upon the analytical investigation, ask the attention of the reader. It is, that
in the present subject, the question of the right application of a formula is quite
distinct from that of the validity of the processes by which that formula is de-
rived from its data. The latter is a question of formal science, the former in-
volves considerations which belong rather to the philosophy of the human mind.

I will first express the problem which we have to consider in a general form,
equally applicable to the combination of testimonies or of judgments. I shall
consider the fact of a testimony having been borne, or an observation made, as a
circumstance or event affecting our expectation of the event to which it has re--
ference.

Prosem II.

34. Required the probability of an event z, when tivo circumstances x and y are
known to be present,—the probability of the event z, when we only know of the eaist-
ence of the circumstance x being p,—and its probability when we only know of the
existence of y being q.

Here we are concerned with three events, 2, y, and z. For convenience and
uniformity I shall, in the solution of the problem, speak of x and y as events, as

632 PROFESSOR BOOLE ON THE COMBINATION

well as of z. A circumstance is an event—a state of things which comes to pass,
or has come forth—evenit.

The data leave wholly arbitrary the probabilities of the event « and y. Thus
p and q are conditional probabilities; p is the probability that if the event «
occur, the event z will occur; ¢ is the probability that if the event y occur, the
event 2 will occur. Hence

__ Prob. xy _ Prob. yz
P=Prob.x? 27 Prob. y AY UD te (1)

Our object is to determine the probability that if the events w and y both occur,
the event z will occur. We have therefore to seek the value of the fraction

Prob. xyz
Prob. xy

or, as for our present purpose it is more convenient to say, of

Prob. xyz
Prob. xyz+ Prob xyz

(2)

In seeking the value of Prob. xyz, which we shall represent by u, the formal
statement of our data and quesitum will therefore be

Prob. r=c, Prob. y=c’
re dai (3)

Cre \ Prob. wz=cp, Prob. yz=c'q¢
Required Prob. ayz.

cand ¢’ being arbitrary constants expressing the unknown probabilities of the
events w and y.

A misconception may here arise respecting the meaning of Prob. x, Prob. y,
which it is worth while to anticipate. In the case of testimony, Prob. 2 would
not mean the probability that a testimony would be borne, but the probability
that the particular kind of testimony actually recorded considered with reference
to its object, credibility, &c., would be borne. Testimonies differ, not merely as
to their degree of credibility, but as to their unexpectedness—as to the surprise
which they occasion. And it is, I think, matter of personal experience that this
unexpectedness is in itself an element affecting the strength of that expectation
which combined testimonies produce. So, too, if v and y are facts of observation,
é.g., observed symptoms of a disease z, the probability of that disease, when both
symptoms present themselves, is not determined by the strength of the separate
presumptions merely, but is consciously increased by our knowledge of the rarity
of the symptoms themselves. And thus the elements Prob. # Prob. y, which
have been introduced by a formal necessity of the statement of the problem are
seen to belong to the very matter of its solution.

Making

a2—S, i ryz=,

OF TESTIMONIES OR JUDGMENTS. 633

we find, by the calculus of logic,

p=nyst+O(wsyttytastaeyst+aeysttyastt+axyst)

: 1
+ terms whose coeficientsare 5 - - - - «+ )

a result which may be verified by the method applied to (14) in Art. 28.
Hence we find, adopting the simplification of Art. 21,

V=ayst+austyt+ayta+ytl,
and since we haye
Prop. v—c, (Erob. g—c’, Prob. s=cp; Prob: t=¢g¢ 5
Prob. vyz=u, ®)
we find, as an algebraic system of equations,
ayst+as+ayt+u — xyst+yt+ry+y
6 ie. c
_ cyst + xs ou vyst + yt
ep Ӣ
= US = wysttastyt+ay taty + 1

This system is easily reduced to the form
CEO Ye OY ee yl

cp—u —s ¢q—u-——sCil+- u—ep—c'g
“+1 - y+l _ xsyt

~1+u—cp-c — 1+u—ce—eq u

(7)

And if we equate the respective products of the first three and of the last three
members of the above, we find

(cp—u) (¢'g—u) (+ u—ep—¢g) = (1+ 4—e—ep) (ltu—c—cgu . . (8)
a quadratic equation by which the value of w must be determined.
If, in like manner, we assume
Prob. ayz=t
we shall find
(cl—p—t) (¢l—g—4) (1+ t—cl—p—c1—g)=(1+t—e'—cl—p) (1+t-e—cl—g)t (9)
From these equations the values of ~ and ¢ being determined, we have finally

Prob. vyz ou

Prob.vy wu+t uD)

Before we can apply this solution, we must determine the conditions of pos-
sible experience, and the conditions limiting the values of w and 7. For this pur-
pose writing

Prob. xyz=u, Prob. xyz=t, Prob, xzy=p. Prob. ayz=y,
Prob. yza =0, Prob. yxz =<,
VOL. XXI. PART IV. 8H

634 PROFESSOR BOOLE ON THE COMBINATION

we have, from the data, the equations,
uttit+pry=e
ut+t+o+o=e¢
Ut = cp
ut oO = c”q
to which must be added the inequations

u>0 tS0 os) y>0 e>0 c>0
utt+pt+yt+oroc<al
Proceeding as in Art. 14, we find ultimately as the conditions of possible ex-

perience

cp <1—c¢' (1—q) eg <1—c(1—p) , : : . ay
together with the usual condition that ¢, ¢’, p and g must be positive proper frac-
tions, or at any rate must not transcend the values 0 and 1. We find, too, as
the conditions limiting w and ¢,

u<cp u<cg
uSct+cq—-1 usc+ep—1 u>0
tZel—p tZcl—q Meneses 2 ns

tSetel—q—-l t5e¢+e—p—1 t> 0

The solution of the problem assumes, therefore, the following form and cha-
racter :—

1st, It involves two constants ¢ and ¢’, which are arbitrary, except in that
they are subject to the conditions (11).

2ndly, The values of w and ¢, determined from (8) and (9), in subjection to the
conditions (12), are to be substituted in the formula (10).

3dly, In the absence of any means of determining ¢ and ¢’, the value obtained
will be indeterminate, except for particular values of p and g. Some general
conclusions may nevertheless be deduced from its expression indicating the man-
ner in which expectation is influenced by circumstances insufficient of themselves
to give to it a definite amount of strength. This will appear from the following
analysis.

Analysis of the Solution.

35. The solution is contained in the numbered results, from (8) to (12) inclu-
sive, of the preceding Article. Of these, (11) expresses the conditions of possible
experience, (12) the conditions limiting w and 7. From (8) and (9), these quan-
ties are to be determined in accordance with (12), and the resulting values sub-
stituted in (10).

By a proper reduction of (8) and (9), the solution may also be put in the fol-
lowing form :—

au? +(cem—aa')u—ac’pq=0 . : 5 : (1)
at? — (c’m+aa')t—a’e’'(1—p) (1—q)=0 . 5 : (2)
where a=cp+ecq-1 a’'=c(l—p)+¢(1 —gq)—-1 m=p+q—1.

OF TESTIMONIES OR JUDGMENTS. 635
The values of wand ¢ hence found, in accordance with the limitations ex-
pressed by (12), are to be substituted in the equation

Prob. zyz _ _&
BunbW eet hat PY si ents Picceticern al 4 @)

The following special deductions may now be noted.

1st, If either of the quantities p and g is equal to 1, the probability sought
is equal to 1, whatever the values of ¢ and ¢’ may be.

Thus let p=1. Then (2) gives <=0; the only value which satisfies the condi-
tions (12), in connexion with (11). The equation (1) is not satisfied by u=0,
whence

U U
ai = 5 = Ih : : P 5 F . (4)

This result is obviously.correct. If, for example, of two symptoms which are pre-
sent, and which furnish ground of inference respecting a particular disease, one
be of such a nature as to make the existence of the disease a matter of certainty-
the fact of that existence is established, however adverse to such a conclusion the
presumption furnished by the other symptom, supposing it our only ground of
inference, would be.

So, too, the verdict of an authority deemed infallible is consistently held to
annul and make void all opposing testimony or argument, however powerful
such testimony or argument, considered in itself, may be.

2ndly, If either of the quantities p and q is equal to 0, the probability sought
reduces to 0, as it Saar ought to do.

3dly, If p = >and Q= = the equations for determining w and ¢ become identical.

Hence w=t, hited

Probability cought,=¢-- =5. ..:--.-.- +. @

This result is quite independent of the values of ¢ and c’. And it is obviously
a correct result. If the causes in operation, or the testimonies borne, are, sepa-
rately, such as to leave the mind in a state of equipoise as respects the event
whose probability is sought, united they will but produce the same effect, whatever
the @ priori probability may be that such causes will come into operation, or
that such testimonies will be borne.

Athly, If c=1, and at the same time c’ is not equal to 0, we find, for the equa-

tions determining w and 7,
(p—u) ('q—u) Uu—p—e'qt+1)=u(u—e¢'—p +1) (u—e'g)
(1—p—2) (cl—q—#) (t—cl—q+p)=t(t—c' +p) (t—c1l—gq)
These give

,

u=Cc'q t=c(1—q)

636 PROFESSOR BOOLE ON THE COMBINATION
as the only values which satisfy (12). Hence

Probability sought = SS gy Set Gs. tat, 2 aaa ne
This result is evidently correct. The probability that such an event will take
place when two other events, w and y, are present, is the same as the probability
that it will take place when the event y is present, if it is known that the other
event z is never absent.
5thly, If c= and g=1—p, we find in like manner u=¢, whence

Probability sought = : og cel ee OS ene

This result is evidently correct. If the events or testimonies w and y are
equally likely to happen, and if the first yields the same presumption in favour
of that event whose probability is sought as the other yields against it, the

chances are equally balanced, and the probability required is =
6thly, But if gy=1—p, while cand ¢ are not equal, then the value of the probability
sought is no longer = It may be shown, by a proper discussion of the formule,

that the presumption afforded by the event «, whether favourable or unfavour-
able, is stronger than the opposite presumption afforded by the event y, when-
ever c is less than c’, and vice versa. And hence it follows, that if there be two
events which, by themselves, afford equal presumptions, the one for and the other
against some third event, of whose probability nothing more is known, then, if
the said two events present themselves in combination, that one will yield the
stronger presumption, which is itself, of the more rare occurrence. This, too, is
agreeable to reason. For in those statistical observations by which probability is
determined, we can only take account of co-existences and successions. We do
not attempt to pronounce whether the presence of the event z in conjunction
with the event « is due to the efficient action of the event x, or whether it is a
product of some other cause or causes. The more frequent the occurrence of 2,
the less entitled are we to assert that those things which accompany or follow
it derive their being from it, or are dependent upon it. If, for instance, « were
a standing event, or a state of things always present, the probability that any
event < would occur when « and y were jointly present, would be the same
as the simple probability of that event z when y was present, and it would be
wholly uninfluenced by the presence of x. This is the limiting case of the gene-
ral principle.

7thly, The case in which e=c and p=gq, is a very interesting one. A careful
analysis leads to the following results.

If there be two events z and y, which are in themselves equally probable, the
probability of each being c, and if when the event x is known to be present, while

OF TESTIMONIES OR JUDGMENTS. 637

it is not known whether y is present or not, the probability of z is p, the same
probability being assigned to z, when it is known that y is present, but not known
whether « is present or not; then, considering p as a presumption for or against

: C 1
z, according as p is greater or less than 5"

1. That presumption is strengthened if the events x and y are known to be
jointly present, 7.¢., the probability of z is greater than p, if p is greater than

‘A but less than p in the contrary case.

2. The strengthening of the presumption is greatest when cis least. In other
words, the less likely the events w and y are to happen, the more does their actual
concurrence strengthen the presumption, favourable or unfavourable, which either
of them alone must afford.

Sthly, If we suppose c and c’ both to approximate to 0, the values of w and ¢

also approximate to 0, and the ratio ss assumes at the limit the form 2 It

may, however, be shown that its actual value at the limit is

Praat E edasire ivesienissars
This is most readily obtained from (1) and (2), by rejecting the terms a’v? and a2?,
which we may do when wu and ¢ are infinitesimal. We thus find that u and ¢ tend
to assume the values ce’pg and cc'(1—p) (1—q), whence
EE ina Wr fet AS Me ld
utt = pg+(1—p) —-g)

It is interesting here to inquire whether the appearance of the limiting value
= ia is due merely to the smallness of cand ¢. In studying this ques-
tion, it occurred to me that it is generally not the mere improbability of events,
or the mere unexpectedness of testimonies considered in themselves, but the im-
probability of the concurrence of such events or testimonies which gives to their
union the highest degree of force. I therefore anticipated, that, if I should in-
troduce among the primary data of the problem, the probability of the concur-
rence of the events w and y, assigning to it a value m, it would appear that, when-
ever m approached to 0, the presumptions with reference to the event z, founded
upon a and y, would receive strength, whatever the values of ¢ and ¢' might be.
And this expectation was verified. On taking for the data

Prob. z=c, Prob, y= ¢, Prob. zy=m, Prob. z= cp, Prob. yz=¢c'q¢

and representing the sought value of Poe by w, I found, for the determina-

nation of w, the equation
(cp—mw) (cg—mw) (l—w) =w(el—p—ml—w) (¢l—g—ml—w) Atel, 449)
VOL. XXI. PART IV. 8I

638 PROFESSOR BOOLE ON THE COMBINATION

the conditions of possible experience being that ¢, c’, p, g, and m, should be posi-
tive proper fractions, subject to the relation

e+e <l+m : a ot . : f . (10)
that root of (9) being taken, which satisfies the conditions

were wed, w<l
—cl—p —c1l—g
l—w ce l-we =

Now if in (9) we suppose m to vanish, we find

epe'g (l—w)=wel—pe1l—q

pg l—w=w 1-p l—q

whence w= (11)

PY
pqy+(1—p) A—-g)

The condition (10) becomes simply ¢+¢ =1. The remaining conditions are all
satisfied by the value of w.

The formula (11), which in the present investigation appears as a kind of
limiting value, applicable only to cases in which the presumption for or against
the event z increases most by the combination of the testimonies given, is usual-
ly regarded as expressing the general solution. The reasoning by which it is
supposed to be established is the following.

Let p be the general probability that A speaks truth, g the general probability
that B speaks truth; it is required to find the probability, that if they agree in a
statement they both speak truth. Now, agreement in the same statement im-
plies that they either both speak truth, the probability of which beforehand is
pq, or that they both speak falsehood, the probability of which beforehand
is (I—p) (1—q). Hence the probability beforehand that they will agree is
pq¢+(1—p) (1—q), and the probability that if they agree, they will agree in speak-
ing the truth, is accordingly expressed by the formula (11).* In the case of 1, tes-
timonies whose separate probabilities are p, p, . . - p,, the corresponding formula is

2 eS ons dithered! dictate
PP, > pap) U7) = Ge)

In applying which, it is usual to regard one of the testimonies as the initial testi-
mony of the mind itself.+ Substantially the same reasoning is applied to deter-
mine the probability of correctness of a decision pronounced unanimously by a
jury, the probabilities of a correct decision by each member of the jury being given.

In this reasoning there is no recognition that it is to the same fact that the
several testimonies are borne. Take the case of two testimonies, and the problem

* Cournor Exposition de la Theorie des Chances, p. 411. De Morean, Formal Logic, p. 191.
+ Formal Logic, p. 195. .

OF TESTIMONIES OR JUDGMENTS. 639

which is substituted for the true one is the following. The probability that A
speaks truth is p, that B speaks truth is g; what is the probability that, if
they both make assertions, and these assertions are both true or both false, they
are both true? Whether A and B make the same assertion or not is assumed
to be a matter of indifference. But this assumption is, in point of fact, as erro-
neous as it is unwarranted. The problem which we have solved in the preceding
sections, interpreted in relation to testimony, is the following. Two witnesses, A
and B, assert a fact. The probability of that fact, if we only knew of A’s state-
ment, would be p, if we only knew of B’s, would be g; what is its probability
when we know of both? ‘The formal expression of this problem will be seen in
Art. 34. The most complete formal expression of the problem which has been
substituted for it, taking into account all its elements, is as follows. Let a
and y represent the testimonies of A and B, w and z the facts to which these
testimonies respectively relate. Observe that no hypothesis is here made as
to the connection, by sameness or difference, of w and z. And the simple ab-
sence of any such hypothesis is properly signified by expressing the events by
different symbols, unaccompanied by any logical equation connecting these sym-
bols.

If we wish to indicate that the events w and z are identical, we must write
as a connecting logical equation,

W=2

though it must be simpler to express the identity by the employment of a single
symbol as before. Any other definite relation may be expressed in a similar way.

The Problem now stands thus :—

Gi Prob. z=c, Prob. zw=cp, (13)
en
A Prob. y=¢, Prob. yz=e'q,
. Prob. vywz
Required i (14)

Prob. vywz+ Prob. ayw z
First, we will seek the value of Prob. xywe.
Let “LW=Ss, y2=t, LYWsZ=V
From these logical equations we must now determine v as a developed logical
function of 7, y, s, and ¢t. The result is
; v=uyst+O(ayst+arytst+aysttusyttayst
+ytastyast+auyst)
+ terms whose coefficients are =

Let u be the value of Prob. v. Then, by the simplification of Art. 21, we
have

640 PROFESSOR BOOLE ON THE COMBINATION

vyst+ vystaryt+Ly+Lst+ ue _ ayst+ vys t+ xyt+ vy t+yt+y
c im é
_avyst+ayst+us — axyst+ayt+yt
aa cp it cq
ayst

Sige vystayt+aytast+at+ytt+yt+ 1

Equating the product of the third and fourth to that of the fifth and sixth mem-
bers of the above system, we have
u=ce'pg=Prob. xywz
whence ec’ (1—p) (1—p)=Prob. «#ywz
And hence

Prob. wywz i Pq
Prob. zywz+ Prob. xyw z pg+(1—p) (l=q)

(15)

Here it will be noted, that although the arbitrary constants ¢ and c’ were neces-
sarily introduced into the expression of the data of problem, they have no place in
its solution. The result, it will also be seen, agrees with (8) ; and it thus shows that
that formula would express the true solution of the problem originally proposed,
if it were permitted to neglect the circumstance that it is to the same fact that
the testimonies have reference, and so to regard their agreement as merely an
agreement in being true or in being false, but not in being true or in being false
about the same thing.

Special Solution of Problem II. founded upon the principle of the limit.

36. In the present investigation we employ the principle stated in Art. 24,
our object being to determine the mean between p and g, when they represent
probabilities founded upon different judgments, just as in Art. 25 we have deter-
mined the mean between p and g, when they represent different observed values
of a physical magnitude.

To the previous data, viz.,

Prob. «=e, Props: 7c, Prob. 22= ep, Prob. yz=¢'q : on Uh)
we now add, as the supposed @ priori value of Prob. z,
Prob. z=r 2 : : : : 4 ee)

From these collective data we determine the fraction

Prob. xyz be Prob. xyz
_ Prob. wy Prob. vyz+Prob. vyz

(3)

representing the @ posteriori value of Prob. z, and, equating the a@ privri and a
posteriorz values, determine 2. The principle upon which the investigation pro-
ceeds, is, that we attribute to the mean strength of the probabilities p and g such
a value, that if the mind had previously to the evidence been in the state of ex-
pectation which that value is supposed to measure, the evidence would not have

“a
a
4

OF TESTIMONIES OR JUDGMENTS. 641

tended to alter that state. By the evidence I mean, of course, that which forms
the basis of the judgments.
Making, as before,
LA=S ya=t LYZ=V

and determining v as a developed logical function of «, y, z, s, and ¢, we find
v=axyzstt O(wyzst+azsytt+yrztustayzst t¥ aust
+2uyst+avyast)
P 1
+ terms whose coefficients are 5-

Hence, availing ourselves of the simplification of Art. 21, we have

ayzst+avy+ur+ae — aeystataytylaty
¢ ie e
_wystz+ usa _— axystatyta
am Sa av e'Ӣ
_aystatasetytate _ xyste
Be r ene

=avystatacyt+usetytatat+ytet+l :
If we equate the product of the third and fourth to that of the fifth and sixth
members of the above system, we find

Prob. 2yz = Pd

whence by symmetry,
e¢(1—p) (1-9)

Prob. zyz = iia (4)
Substituting these values in (3), we have
Prob. wyz _ pq-r) (5)

Prob. zy ~— pq(l—r)+(1—p) (1—-q)r

Before proceeding further, it will be well to note that in this formula p and q
represent, not the general probabilities which the testimonies or evidences
upon which our judgments are founded would give to the event z, but the proba-
bilities which they would separately produce in a mind embued with a previous
expectation of the event z, the strength of which is measured by r. And there
are some curious confirmations of the truth of the theorem, two of which I shall
notice.

If we represent the a posteriori value of Prob. z by R, and accordingly make

pg(1—r) 255) WY phe

pg (l—r)+(1—p) (l-@)r (6)
we find, on solving the equation relatively to r,
pq (1—R) i

pga—R)+(i-p)A-gR Pe ENS FY C7)

VOL. XXI. PART IV. 8K

642 PROFESSOR BOOLE ON THE COMBINATION

from which it appears, that if r is the @ priori expectation of an event z, and if
evidences are presented which severally would change + to p and 4, and unitedly
would change it to R; then, reciprocally, if R measured the @ priori expectation
of the event, and evidences were received which would severally change it to p
and q, unitedly they would reduce it tor. Now this is evidently what ought to
be the case, since testimonies simply countervailing those by which 7 was
changed to R, would simply undo what was done, and again reduce R tor.

We see that p and g being the same, R is greater when 7 is less, and less
when r is greater; and this, though it is contrary to what we might at first ex-
pect, is agreeable to reason. For the effect of evidence is to be measured, not by
the state of expectation which exists after it has been offered, but by the degree
in which the previous state of expectation has been changed by it. Suppose p
and g much greater than r, which we will conceive to be a small quantity, then
the separate evidences greatly increase the probability of an event which was be-
fore very improbable; and unitedly they do this in a much higher degree than if
the separate evidences had merely been such as to raise to the measures p and g,
an expectation which was before not much below these measures.

Now, introducing the principle of the mean already explained, Art. 24, let us
in (6) make R=7, we have

pg (l—r) afl
pq(l—r)+(—p) d—-g)r
and solving this equation relatively to 7, we find
Z vPq
"“Vog OF Eg Pe ene

the formula required.
37. Upon this result, the following observations may be made :—
In the first place it may be shown, from the formula itself, that it always ex-
presses a value intermediate between the values p and g. Thus we have
Dia = —P
Vpq+¥v (1—p) (1-9)
_Vq-p)-V9 0-9)

eee aE ee | ara iaes 4 9
Jpq+V (=p) (1=q) ©? OP? ®)
on reduction. In like manner we have
_ Vp d=g—-V9 =p) 7
od is i

Vpq+V1—p 1l—q

As p and q are positive fractions, the values of r—p and r—q, given in (9) and
(10), are clearly of opposite signs, whence 7 must lie between p and q.

OF TESTIMONIES OR JUDGMENTS. 643

In the second place, it may be shown, that 7 approaches more nearly to that
one of the two values p and g, which most nearly approaches either of the limits
0 and 1. To show this, let us suppose qg greater than p, and let us first inquire,
under what circumstances 7 approaches more nearly to ¢ than to p.

We must then assume

Gn <r —p
Substituting the values of these members from (9) and (10) we have
vq 1=p)—Vp (1=9) vq d—p)—Vp A=9)
V'pqgt ¥ (1p) 1-9) Vpq+V (1—p) (1—q)

Now, g being by hypothesis greater than p, it is evident that /g (1—p) —Vp (1—q)
will be positive. Rejecting, then, the common positive factor on both sides of the
inequation we have

xV7¢(l—q) < x Vp (1—p)

vq (1-49) < Vp (=p)
q-F <P-p°
CP
and dividing both sides by the positive factor g—p

l<ptg
l-q<p
a condition which shows that g must be nearer to 1 than p is to 0.

On the other hand, as would appear from the very same analysis, changing
only the signs < into >, the condition that 7 may approach more nearly to p than
to g, is that p may be nearer to 0 than q is to 1.

Now, 1 and 0, as limiting the measures of probability of the event z, indicate,
the one that it certainly will, the other that it certainly will not occur, And the
approach of any measure of probability to these limits indicates the approach of
the probability to certainty. We see, then, that when p and gq are measures of
the probability of an event founded on different judgments, the mean between
these measures, as determined by (8), will not be the usual arithmetical mean, but
will always fall nearer to that one of the two values p and g which expresses a
probability the most nearly approaching to certainty.

Now, this seems to be in accordance with reason. Evidence of any kind
which enables us to pronounce a judgment with certainty, entirely preponderates
over that which only enables us to affirm a probable judgment, Art. 35. And
the more of the character of certainty that is possessed, the greater is the weight
which is due to the evidence to which it belongs.

38. By an analysis similar to that which is applied in the previous sections, I
have determined the general value of 7, when the number of judgments is », and

644 PROFESSOR BOOLE ON THE COMBINATION

the values which they respectively give to the probability of the event z are p,
D,.- Pp» The result is

= (>, P» ee Pa) .
(ripe. +p. )* + (A=p) G=p) 0-2) Je

This is the general formula of the mean in reference to judgments, and much as
it differs from the formula of the mean, in reference to the observations of a
physical magnitude, some remarkable points of analogy exist. I will notice but
one. The arithmetical mean is not altered if to the quantities among which it is
taken we add another equal to the previous mean. Thus we have

Pit Po +» +Pns1 — Pit Po - > + Pn
n+1 nN

provided that Pa+1 =fith-: +P Or representing

Pit P2 a +Pn b
N nN

y P, we have
Past =? n
provided that
Prixz= P : . . . (2)

The same relation may readily be shown to hold also, if P,, represent the mean of
judgment, as expressed in (1).

39. The following is a brief summary of the conclusions established in this
paper.

1st, The solution of the problem of astronomical observations by the logical
theory of probabilities is, in its general form, indefinite.

2ndly, It becomes definite, if we introduce the general principle of means. The
result is in accordance with the usual formule, but expresses the so-called weights
of the observations as determinate functions of certain probabilities relating to
the correctness of the observations, and the character of the observers.

3dly, When, as respects the two last elements, the observations are considered
equal, the formula is reduced to the expression of the arithmetical mean.

4thly, The complete solution of the problem of the combination of two proba-
bilities of an event founded upon different testimonies or judgments is indefinite,
but admits, in various cases, of being reduced to a definite form.

5thly, This indefiniteness is due to the circumstance indicated by the formula,
that the strength of the probabilities in combination is due, not to the strength
of the separate probabilities alone, but also to the degree of unexpectedness of
the testimonies or judgments themselves.

6th/y, Combined presumptions, whether for or against an event, are generally
strengthened by the unexpectedness of the combination.

vthly, When probabilities as p,,p,,. .p, are in a high degree cumulative, owing

OF TESTIMONI¥S OR JUDGMENTS. 645

to the exceeding improbability @ priort of their enmbination, the expression for
their united force tends to assume the form

Pi Po + + Pn
Py Po + » Pat (1—p,) 1—p,) . - pn)
commonly assumed to express the general solution.

Sthly, When the probabilities are so far from being cumulative that we feel
that we ought to take a mean between them, the above formula is replaced by
the following, viz. :—

1
{Ps Ps one p, }a

{ PyPs += Pr }e + { G=p.) (=p) (ip, ) \e

9thly, This formula takes, in reference to ordinary judgments, the place of the
arithmetical mean, with relation to the problem of astronomical observations,
both being expressions of a more general principle.

40. It will probably appear to some of the readers of this paper, that I have
dwelt more upon questions of philosophy and of language, than it is usual to
do in mathematical treatises, and that I have also, in various parts, assumed.
the office of a critic, rather than that of an expositor of original views. Respect-
ing the first of these points, I will only express a hope, that I have nowhere
in this paper entered into discussions that are not strictly relevant to the subject.
Upon the second, I have to observe, that the theory of probabilities is one in which
as it seems to me, the critical office is especially needed. I do not think that it
is likely to gain much advance from mere analysis. As respects the original
portions of this paper, it is my strongest wish, that they should be regarded chiefly
as materials for future judgment. Thus it is possible that the theory which I
have developed with reference to problems of which the elements are logical, may
be found to involve inconsistencies as a scientific theory, though I do not think
this likely to be the case. But whether that theory shall finally be accepted or
not, it is, I conceive, of some present importance, to establish the necessary de-
pendence of any theory, professing to deal with the same class of problems, upon
what I have termed the conditions of possible experience,—to show how those con-
ditions may be determined, and how they are to be applied. As respects the so-
called principle of the mean, applied in certain portions of this paper, it is open
to inquiry whether it in all cases leads to results possessing the characteristic
property, noted in Art. 38, and the decision of this question would materially
affect our estimate of its value. Lastly, it is, I think, highly probable, that con-
ditions which we do not yet know of may be discovered, affecting, not the possi-
bility of the data of a problem as discussed in this paper, but their adequacy,
and the principles which, in statistical research especially, ought to guide us in
their selection. lam so conscious how limited, imperfect, and in some cases fluc-

VOL. XXI. PART IV. 8 L

646 PROFESSOR BOOLE ON THE COMBINATION

tuating my own views upon important questions connected with this subject are,
that I should regret having engaged in inquiries so lengthened and laborious
as those of which I now take leave, if I did not think that as materials for future
judgment, they may possess value and importance. And although the interest
attaching at present to these inquiries is chiefly speculative, it may be that they
will yet be found to possess a practical utility. The vast collections of modern
statistics seem to demand some kind of reduction. I am sure that all who read
this paper will feel that even towards this end I regard the labours of the mathe-
matician as contributing only in a secondary degree.

APPENDIX A.

The following proposition in Algebra is of extreme importance in connection
with the theory of probabilities. It was originally published by me in the Phi-
losophical Magazine for March 1855; but the present paper would be incomplete
without some notice of it.

PROPOSITION.

If V be a rational and integral function of n variables z, y, z . ., involving no
power of these variables higher than the first, and having all its coefficients posi-
tive, and being complete in all its terms, then if V,, represent that part of V which
contains z, V, that part which contains vy, and so on; the system of equations

Se ih No fs
ie
p, q, &e. being positive fractions, admits of one solution, and of only one solution,
in positive values of z, y, z . .
To exemplify this proposition, let us suppose

.=V 4 : : : : 5 (1)

V=aay+be+cy+d
a, 6, c, and d being all greater than 0; then it is affirmed that the system of
equations
axyt+be axy+cy
pres rere
p and q being positive, admits of one, and only one solution, in positive values
of x and y.
The proposition is true when x=1. For then V=ax+b and the system (1) is
reduced to the single equation

=axy + ba +ey+d , , : (2)

ax
—=arr+b
P
Whence we have

and this value is positive if a and 4 are positive, and p a positive fraction.

OF TESTIMONIES OR JUDGMENTS. 647

The general proof consists in showing, that if the proposition is true for a par-
ticular value of n, it is true for the next greater. Whence, being true for the
case of n=1, it is true universally. I will exemplify the method by showing how
the truth of the proposition, when n=2 is dependent upon its truth when n=1.

Let n=2, then we have to consider the system (2), which may be reduced _ to
the form

any + bx ies

amytba+eytad ? : ; ; (3)
ALY + Cy 2h

axy+bu+cyta 4 Gt UY ca ta ce

Let us represent by Y the variable value of the first member of (4), when z and
y are supposed to vary in subjection to the single condition (3). We have then
any + cy
aany + ba ey Fd ee
Now differentiating (3) and (5) relatively to z and y, we find, after slight re-
ductions,
(ay +b) (cy +d) dx + (ad—be) xady=0 : ; : (6)

7 ja r+¢)(be+d
ay =O Way ee Ely Rar ea CN

where, as before, V=axy+be+cy+d. Substituting in (7) the value of dx found
from (6), we have
_(av+e) (ba +d) (ay+b) (cy+d) —(ad—be) xy
ae (ay +b) (ey +d) V? ay
The numerator of this expression may be reduced to the form

V (abcay + abda + acdy + bed)
whence
dY abcay + abdx + acdy + bed P
dy — (ay+b) (ey+d) V * pinghs Qala Saetind
This represents the differential coefficient of Y taken with respect to y as indepen-
dent variable, z being regarded as a function of y determined by (3). The ex-
pression is always positive, if z and y are positive.
Now let y vary from 0 to « through the whole range of positive magnitude.
Writing (3) in the form
Ax
ABER p ; ; . : ; : (9)
where A=ay+b, B=cy+d, the quantity z must, by reference to the case of »n=1,
have a positive value, since A and B are positive and p fractional. Whence, as

y varies from 9 to «, the value of is always positive.

Now when 7=0, Y=0, and when y= «, Y=1, as is evident from (5). Therefore,
as y increases from 0 to «, Y continuously increases from 0 to 1. In this variation

648 PROFESSOR BOOLE ON THE COMBINATION

it must once, and only once, become equal to g. Wherefore the system (3) (4)
admits of one, and only one, solution in positive values of # and y.
The reasoning might also be presented in the following form. The condition
of Y having a maximum or minimum value is expressed by the equation
abcxy +abde+acdy+bed=0 . - - é : (10)

It is obvious that this, as all the terms in the first member are positive, can
never be satisfied by positive values of z and y Hence Y has no maximum
or minimum, consistently with (3) being satisfied, and thus it never resumes a
former value, and is only once, in the course of its variation, equal to q.

In the case of n=3, we have

V =aayz+ byz+caz+dayt+ec+fyt+gzth
and the system to be considered is
axyit+cuz+dxy+ex _

p : : : ; : (11)

axnyor byz+day + fi
eee (12)

axyz+ byz+ cx2 + 9%
= Lt

Let the first number of the last equation, considered as a variable function of

2, y, be represented by Z, and suppose a, y, and z to vary in subjection to the
conditions (11) (12). Just as before, it may be shown that Z increases continu-
ously with z. The condition of Z having a maximum or minimum value, will be
expressed by the following equation:

(D+H+E+F) (ABC +ACG + ABG+ BCG)

+(A+B+C+G) (DHE+ DHF + DEF + HEF)

+ (AC+ BG) (DF + DH+ EF + EH)

+(AG+BC) (DF +EH + DE+FH)

+ (AB+ CG) (DE+DH+ FE+ FH)

+4 AGFE+4 BOCDH = 0 : : : : : (14)
Wherein
A=axyz B=byz ENOL D=dzy
E=ex F=fy G=gz H=h

And as this equation has positive values only in its first member, it cannot be
satisfied by positive values of z, y, z; whence, by the same reasoning as before,
the system (11), (12), (13) cannot have more than one solution in positive values
of x, ¥, 2.

To show that it will have one such solution, let z vary from 0 to «, then Z
continuously increases from 0 to 1, and once becomes equal to 7. At every stage
of its variation we may give to (11) and (12) the form

OF TESTIMONIES OR JUDGMENTS. 649

Aay+ Ba _

ieee Ae

Aay + Cy

a = 4
which corresponds with the form of the general system (3) (4) in the case of n=2.
Whence, for each positive value of z, one positive set of values of x and y will be
found. The system (11), (12), (13) admits, therefore, of one solution in positive
values of x, y, z, and of only one.

To prove the proposition generally, it ought to be shown that the function
exemplified in the first members of (10) and (14), for the cases of n=2 and n=3
possesses universally the same property of consisting only of positive terms. I
have proved that it does for the case of n=4, and the analysis was such as to leave
no doubt whatever of its general truth.

I will now offer a few remarks on the application of the above proposition.

The system of equations for determining s and ¢. ., Art, 21, is of the form
V, V;

sid aie Po ei eng)

V being a function of the same general character as the one discussed in the
foregoing proposition, but with this difference, that its coefficients, if we regard —
it as a complete function, are all equal either to 1 or to 0.

Thus in Art. 18, we have

Vestutstt+u+l |
Here the terms st, tv, and vs, must be considered as present, but with the coeffi-
cient 0.

This limitation does not affect the essentially positive character of the deter-
mining function exemplified in (10) and (14). Whence the system (15) cannot
have more than one solution in positive values of s, ¢, &c. This shows that the
solution of the system of equations furnished by the general method can never be am-
biguous.

The vanishing of some of the coefficients of V does, however, affect the rea-
soning by which it has been shown, that for the general form of V discussed in
the last proposition, one solution of the algebraic system in positive values will
exist. Thus Y in (5) does not vanish with y, if both 6 and d vanish. And gene-
rally this vanishing of coefficients in V entails conditions among the quantities
p. 9,7 - ., in addition to that of their being fractional, in order that the derived
algebraic system may admit of a solution in positive values.

Thus if we take, as in (7) Art. 18,

V=siv+st+ttu+l
with the derived algebraic system
stu+s stu+t stu+v
ea) Oa ee

V V V
VOL. XXI. PART. IV. 8M

650 PROFESSOR BOOLE ON THE COMBINATION

it is evident that if s, 1, and v are positive quantities, and if we write

stu 8 t 7)
77, lage ee Wg Nara
u, A, pw, and y must be positive fractions, whence, in addition to the equations
u+A=p
utp=q
utv=r
we shall have the inequations
usS0 ASO uso yS0

ut+A+pmt+vel

This system is identical with the one obtained in 10, Art. 13, for the determi-
nation of the conditions of possible experience in the particular question of Proba-
bilities, in which the above function V presents itself. And a very little attention
will show, that if in any case we express as above the relations which must
obviously be fulfilled in order that s, ¢, &c., may be positive quantities, we shall
form a system of equations and inequations precisely agreeing with those which
we should have to form in order to obtain the conditions of possible experience,
if we sought those conditions, not from the data in their original expression, but
from the translated data, as employed in Art. 13.

Hence, in order that s,t . . in the system of Art. 21, may be positive, or in the
prior system, positive fractions, the problem of which these systems of equations in-
volve the solution must represent a possible experience.

Conversely if that problem represent a possible experience, the quantities s,t . .
will admit of being determined in the system of Art. 21, in positive values, or in the
prior system, in positive fractional values.

I have not succeeded in obtaining a perfectly rigorous proof of the latter, or
converse proposition in its general form, but I have not met with any individual
cases in which it was not trne. I will here only exemplify it in Problem IL,
Art. 34.

Here the value of V is

V=ayst+ust+yt+ay+atyt1
and the algebraic system employed in the determination of Prob. xyz is

vyst+astayt+a_ xystt+yt+ayt+y
c rf

_ ayst+aus_ xystt+yt _ ayst
rep “TONG GMS She
=aysttastyt+aytatyt1l |... (16)
For the determination of w we hence find the following equation—

u(u—e+ep—1) (u—e +e’ g—1)—(cp—u) (c' g—u) (u—cp+¢q—1)=0 (17)

OF TESTIMONIES OR JUDGMENTS. 651

the conditions of limitation being
u> 0 u>c+cp—1 u>et+eq-1l
u< cp u<eg : : 5 : (18)

Now, since w is greater then c+¢q—1 itis a fortior? greater then cp+c’qg—1. Thus
within the limits assigned to w, all the factors of each term of (17) will be positive.

If then we give to w the value which belongs to the highest of its inferior
limits, the first member of (17) will be reduced to its second term, and will be
negative. If we give to w the value which belongs to the lowest of its superior
limits, the first member of (17) will be reduced to its first term, and will be
positive. Moreover, that member is a quadratic function of w. Hence there is
one root, and only one, within the limits specified.

We must now express #, y, s, and ¢, in terms of vw. Their values determined
from the system (16) are as follows, viz. :—

paca RSE e'(1—g)
u—(+¢q-1) u—(c+ep—1)
gee u—(c+eq—1) i tee
c(1l—p) cq-—u
pa u—(c+ep~l) iu
e(1—q) cp —uU

All these expressions become positive when w is determined in accordance
with the conditions (18).

It would seem from the above, as well as from reasonings analogous to those
of Proposition I., that when the algebraic system belonging to a problem in the
theory of probabilities is placed in the form

Va Vy

Wit 2iyos eee
the limits of variation of the first member of any equation subject to the condi-
tion, that the variables shall all be positive, and shall vary in subjection to all
the other equations of the system, will not in general be 0 and 1, as in the case
contemplated in Prop. I., but will correspond with the limits of value of the
second member of the same equation as determined by the conditions of possible
experience.

This conclusion I have in various cases independently verified. The analytical
theory still, however, demands a more thorough investigation.

APPENDIX B.

A note to Archbishop WuaTELy’s Logic, Book III., sec. 14, contains a rule
for computing the joint force of two probabilities in favour of a conclusion which,
as actually applied, is at variance with the preceding results. For this reason,

652 PROFESSOR BOOLE ON THE COMBINATION

and also because the validity of the rule in question has been made the subject of
recent controversy, I design to offer a few remarks upon the subject here. The rule
is contained in the following extract. ‘‘ As, in the case of two probable premises,
the conclusion is not established except on the supposition of their being both true,
so, in the case of two (and the like holds good with any number) distinct and inde-
pendent indications of the truth of some proposition, unless both of them fail, the
proposition must be true: we therefore multiply together the fractions indicating
the probability of failure of each,—the chances against it;—and the result being
the total chances against the establishment of the conclusion by these arguments,
this fraction being deducted from unity, the remainder gives the probability for it.
E.g., A certain book is conjectured to be by such and such an author, partly, 1s¢,
from its resemblance in style to his known works, partly (2d/y\, from its being at-
tributed to him by some one likely to be pretty well informed: let the probability
of the Conclusion, as deduced from one of these arguments by itself, be supposed
2, and, in the other case 7; then the opposite probabilities will be, respectively,
2 and +; which multiplied together give 32, as the probability against the Con-
clusion; 7.¢., the chance that the work may not be his, notwithstanding those rea-
sons for believing that it is: and consequently the probability in favour of that
Conclusion will be 32, or nearly 3.”

A confusion may here be noted between the probability that a conclusion is
proved, and the probability in favour of a conclusion furnished by evidence which
does not prove it. In the proof and statement of his rule, Archbishop WHATELY
adopts the former view of the nature of the probabilities concerned in the data.
In the exemplification of it, he adopts the latter. He thus applies the rule to
a case for which it was not intended, and to which it is in fact inapplicable.

The rule is given, and the conditions of its just application are assigned in
Professor De Morcan’s Formal Logic, p. 201. Its origin may be thus explained.
Let there be two independent causes, A and B, either of which, when present, neces-
sarily produces an effect E. Let a be the probability that A is present, } the probabi-
liy that B is present; then 1—a is the probability that A is absent, 1—3 the proba-
bility that B is absent, (1—a) (1—b) the probability that they are both absent;
finally, 1—(1—a) (1—b) the probability that they are not both absent. This, then,
is the probability that one at least of the causes is present; and therefore it is
the probability that the event E, so far as it is dependent upon these causes, will
occur. In its special application to arguments viewed as causes of belief or ex-
pectation, it would lead to the following theorem. If there are two independent
arguments in favour of a conclusion which the premises of either, if granted, are
sufficient to establish, the doubt only existing as to the truth of the premises, and if
the probability that the premises of the first argument are true is a, the probability
that the premises of the second argument are true }, then the probability that
the conclusion is established is 1—~(1—a)(1—d). Interpreted, this formula gives

OF TESTIMONIES OR JUDGMENTS. 653

Archbishop WuaTELy’s rule, but the conditions of its valid application are evi-
dently not fulfilled in the example which he has given. To satisfy these condi-
tions, this problem ought to be changed into the following: “ There exists a certain
quality of style, the possession of which would prove the work to be by the au-
thor supposed. The probability that the work possesses that quality is 2. There
is a person so well informed that his attributing the work to the supposed
author would be conclusive. The probability that he does attribute it to the
author in question is 2. Required the probability, on these grounds, that the
supposed author is the real one.” But this is evidently not the sense in which
the problem was meant to be understood. Thus to take one point, it is not the
quality of the style that is a matter of probability, but the mode in which a
known and observed quality affects the question of authorship.

Taking the problem in its intended meaning, each of the fractions 2, 2, mea-
suring, not the probability of the truth of certain premises, but the probability
drawn from these premises, as conditions, in favour of a certain supposition
(1 use this word in preference to conclusion), we are no longer permitted to
apply the formula above determined. And we are not permitted to do so, because
the probabilities with which we are concerned are conditional, and their possession
of this character greatly increases the difficulty of the problem. Its rigorous formal
solution is given in Art. 34, and shows that the probability sought is, generally
speaking, indefinite,—a result which agrees with the conclusions of Bishop TER-
ROT, by whom the error to which attention has been directed was first pointed
out, Transactions of the Royal Society of Edinburgh, vol. xxi., p. 369.

I trust that I have not in any way misrepresented Archbishop WHATELY’s
reasoning ; and I am the more encouraged to believe that I have not, as a defence
of it which appeared in the United Church Journal expressly proceeds upon the as-
sumption that the probabilities with which we are concerned are probabilities that
the authorship is proved. To this view Bishop TEerror justly demurred. Nor
was its inconsistency materially diminished by assigning to proof a meaning less
absolute than belongs to demonstration. For whatever degree of cogency,—of
power to produce conviction,—we suppose to characterize proof, the thing itself
belongs to consciousness, and the question whether given evidence is sufficient
to convey proof to our minds or not, is a matter of knowledge, not of probability.

VOL. XXI. PART IV. 8N

PROCEEDINGS

OF THE

STATUTORY GENERAL MEETINGS,

LIST OF MEMBERS ELECTED AT THE ORDINARY MEETINGS,

SINCE NOVEMBER 22, 1852 ;

WITH

LIST OF DONATIONS TO THE LIBRARY,

_ FROM DEC. 9, 1858, TILL APRIL 20, 1857.

EVAR RTI Go

\ iwr % 3 ; “

e

EAHEKID YHORUTATS

tre (gtoaid ete Foe ee

PROCEEDINGS, &.

Monday, November 28, 1853.

At a Statutory General Meeting, Dr Curistison, V.P., in the Chair, the following
Office-Bearers were duly elected :—

Sir T. Maxpoveatt BrisBane, Bart., G.C.B., G.C.H., President.
Sir D. Brewster, K.H.,
Very Rev. Principal Lrz,
Right Rev. Bishop TzRRoT,
Dr CuristIson,

Dr Atison,

Vice-Presidents.

Hon, Lord Murray,
Professor Fores, General Secretary,
Dr GreGory,

Secretaries to the Ordi Meetings.
Professor SmyTH, \ 7eeeue rdinary Meeting:
Joun Russext, Esq., Treasurer.
Dr Traut, Curator of Library and Instruments.

James Witson, Esq., Curator of Museum.

COUNSELLORS.
Rosert CHaMBeERs, Esq. Awyprew Coventry, Esq.
J.T. Grpson-Craie, Esq. Rev. Dr James Grant.
Witi1am Sway, Esq. Rey. Professor KELLAND.
Prof. Witt1amM THomson. Dr Grorce Witson.
Dr J. H. Bennett. CuarLes Maczaren, Esq.
Dr J. H. Batrovr. Rev. Dr Ropert Lez.

The following Committee was appointed to audit the Treasurer’s accounts :—
J. T. Grsson-Crate, Esq. ANDREW CovEntry, Esq. Jamzs CunnincHam, Esq.

The Meeting then adjourned.
(Signed) JOHN LEE, V.P.

Memorandum.—November 28, 1853.—At a Statutory General Meeting of this date, Dr
CHRISTISON, V.P., made a preliminary statement on the part of the Council to the following
effect :—

That, as it appeared from a recent correspondence, that Professor FORBES considered
his former resignation of the office of General Secretary to stand good without any formal
renewal of it, the Council had taken into consideration the most advisable course of proce-

VOL. XXI. PART Ivy. 8 0

658 PROCEEDINGS OF STATUTORY GENERAL MEETINGS,

dure to be followed in consequence of Professor FORBES’s continued indisposition ; and having
been apprised that such an improvement had taken place in Professor ForBES’s health as to
warrant strong hopes of his being able to return to Edinburgh, and to business, in the course
of next year; and being also well satisfied with the manner in which the duties of the Se-
cretaryship have been discharged in his absence, the Council had resolved to recommend to
the Society that the arrangement of the past Session should be continued for another year.

That the Council having been further informed that Professor ForBes had intimated
that he could not accept the usual salary of office for last year, they resolved also to recom-
mend that Mr WILSON be requested to accept the said salary for his services during the
preceding Session, and to grant the continuance of these services for the present Session
upon the same terms.

The above recommendations were then unanimously adopted and confirmed by the
General Meeting of the Society.

Memorandum.—December 19, 1853.—At the Ordinary Meeting of this date, the Acting
General Secretary, on the part of the Council, stated that Dr GrorGE Buist of Bombay had
been duly elected a Fellow of the Society in the Session of 1845-6, but had not been enrolled
in consequence of his absence in India, where he had, until very recently, resided ; that an-
ticipating only a short residence in India after his intended return thither, he was desirous
to become a resident Fellow of the Society, and that the Council, having taken into consi-
deration the circumstances of the case, had agreed to recommend that Dr Buist be enrolled
on payment of the usual admission-money, and the annual subscription for the current Session,
without the exaction of arrears.

Whereupon it was moved by Dr GREVILLE, seconded by JAMES CUNNINGHAM, Esq.,
and unanimously agreed to, ‘‘ That Dr Burst having been duly elected a Fellow of this
Society in the Session of 1845-6, during his absence in India, be now received as an Ordi-
nary Resident Member on payment of his entrance money, and annual contribution for the
current Session.”

Monday, November 27, 1854.

At a Statutory General Meeting, Principal Lex, V.P., in the Chair, the following
Office-Bearers were duly elected :—

Sir T, Maxpovea.t Brissane, Bart., G.C.B., G.C.H., President.
Sir D. Brewster, K.H.,
Very Rev. Principal Lez,
Right Rev. Bishop TrrRor,
Dr CuristTIson,

Vice-Presidents.

Dr Attson,

Hon. Lord Murray,
Professor Forzzs, General Secretary.
Dr Grecory,

Secretari i ‘
Dr Bazrour, } ecretaries to the Ordinary Meetings.

AND LIST OF OFFICE-BEARERS ELECTED. 659

Joun Russexz, Esq., Treasurer.
Dr Trait, Curator of Library and Instruments,
James Witson, Esq., Curator of Museum.

COUNSELLORS.
Dr J. H. Bennett. Rev. Dr Rozert Lez.
Anprew Coventry, Esq. Professor C. Prazzi Smytu.
Rey. Dr James GRANT. Hon. B. F. Primrose.
Rev. Professor KELLAND. Sir Witiiam Gipson-Cratc, Bart.
Dr GrorcEe WILSON. Major Epwarp Mappen.
Cuartes Macuaren, Esq. James CUNNINGHAM, Esq.

The following Committee was appointed to audit the Treasurer’s accounts :—
Awnprew Coventry, Esq. James WALKER, Esq., W.S. Wix11am Tuos. THomson, Esq.

The Meeting then adjourned.
(Signed) R. CHRISTISON, V.P.

Monday, November 26, 1855.

At a Statutory General Meeting, Dr Curistison, V.P., in the Chair, the following
Office-Bearers were duly elected :—

Sir T. Maxpoucatt Brissane, Bart., G.C.B., G.C.H., President.
Sir D. Brewster. K.H.,
Very Rev. Principal Lez,
Right Rev. Bishop TERRor, Mice Paanidckts,
Dr CuristIson,

Dr Auison,

Hon, Lord Murray,

Professor Forzzs, General Secretary.

Dr Grecory, 4 . :

De Bardo, } Secretaries to the Ordinary Meetings,
Joun RussEtz, Esq., Treasurer.

Dr Traxx, Curator of Library and Instruments.

James Witson, Esq., Curator of Museum.

COUNSELLORS.
Dr GrorcEe WILSON. Sir Wit11am Gipson-Craic, Bart.
Cartes Macraren, Esq. James CunnincHaM, Esq.
Rev. Dr Rozert Lez. Dr GREVILLE.
Professor C. Prazzt Smytu. A. Keitu Jounston, Esq.
Hon. B. F. Primrose. Dr Mactacan,

Colonel Mappen. Witiam Swan, Esq.

660 PROCEEDINGS OF STATUTORY GENERAL MEETINGS,
The following Committee was appointed to audit the Treasurer’s accounts :—
J. T. Grpson-Craie, Esq. Davin Smirtx, Esq. James CunnineHam, Esq.

The Meeting then adjourned.
(Signed) Jonn Luz, V.P.

Memorandum.—November 26, 1855.—At a Statutory General Meeting of this date,
Professor CHRISTISON, V.P., in the Chair, the following Resolution was moved by the
Treasurer, and unanimously adopted :—

‘1, That it having been reported to the Royal Society by the Council, that Sir THomas M.
BrisBaNE, the venerable and respected President of the Society, has instituted a Prize, to be called
“ Tae MaxpouGaALL BrisBaNE Prizz,” to be awarded by the Council of the Society, in such manner
and for such purposes as shall be deemed most expedient for the promotion and advancement of science,
the Society takes the opportunity of the first meeting of the session to record the great satisfaction with
which it receives this proof of Sir T. M. Brispanz’s continued zeal to promote the interests of science,
and its grateful sense of the confidence reposed by him in the Society, by conferring on the Council such
large and discretionary powers as to the mode of awarding the prize.

‘‘The Society has always viewed with pleasure the connection which has so long subsisted
between it and Sir T. M. Brisbane as its President, from which this Society has derived so much
benefit and so much honour; and it will henceforth consider the “‘ MakpouGcaLtL BrisBANE PRIZE” as
a permanent and pleasing memorial of that connection.

“2, That a copy of the above resolution be sent to Sir Tuomas M. BrisBanez.”

Monday, November 24, 1856.

At a Statutory General Meeting, Principal Lun, V.P., in the Chair, the following
Office-Bearers were duly elected :—

Sir T. Maxpoueatt BrisBane, Bart., G.C.B., G.C.H., President.
Sir D. Brewster, K.H.,
Very Rev. Principal Lex,
Right Rev. Bishop Terror,
Dr CurisTIson,
Dr ALIson,
Hon. Lord Murray,
Professor Forses, General Secretary.
Dr Gretcory,
Dr Batrour, }

Vice-Presidents.

Secretaries to the Ordinary Meetings.

Joun Russet, Esq., Treasurer.
Dr Doveras Mactaean, Curator of Library and Museum.

COUNSELLORS.
Hon. B. F, Primrose, Dr TRAILL.
James Cunnineuam, Esq. Hon, Lord Nzaves.
Dr GREVILLE. Dr Tuos. ANDERSON, Glasgow.
A. Keiru Jounston, Esq. Rey. Dr Hopson.
Dr Macragan. Rosert CHAMBERS, Esq.

Wa. Swan, Esq. J. T. Grsson-Craic, Esq.

|
|

AND LIST OF OFFICE-BEARERS ELECTED. 661
The following Committee was appointed to audit the Treasurer’s Accounts :—
J, T. Grpson-Cratic, Esq. Joun Mackenziz, Esq. James CunNINGHAM, Esq.

The Meeting then adjourned.

Memorandum.—January 5, 1857.—At the ordinary Meeting of this date, Dr Curist1-
SON, in the absence of Mr RUSSELL, the Treasurer, proposed that the following motion,
tabled on the 1st December, be carried :—

That the Meeting do resolve that Laws II., III., and IV., and Law XVI., be altered and stand
as follows :—[The alterations are printed within brackets. ]

Law II.

Every Ordinary Fellow, within three months after his election, shall pay [Two] Guineas as the
fee of admission, and Three Guineas as his contribution for the Session in which he has been elected—
and annually, at the commencement of every Session, the like sum of Three Guineas ; [that this annual
contribution shall continue for ten years after his admission, and thereafter it shall be limited to Two
Guineas for fifteen years thereafter. ]

Law ITI.

All Fellows who shall have paid twenty-five years’ annual contribution shall be exempt from
farther payment.

Law IV.

The fees of admission of an Ordinary Non-Resident Fellow shall be £26, 5s., payable on his
admission ; and in case of any Non-Resident Fellow coming to reside at any time in Scotland, he shall,
during each year of his residence, pay the usual annual contribution of £3, 3s. payable by each Resi-
dent Fellow, but after payment of such annual contribution for eight years he shall be exempt from any
further payment.

In the case of any Resident Fellow ceasing to reside in Scotland, and wishing to continue a
Fellow of the Society, it shall be in the power of the Council to determine on what terms, in the
circumstances of each case, the privilege of remaining a Fellow of the Society shall be continued to
such Fellow while out of Scotland.]

Law XVI.

That the words “‘ and an Assistant Curator,” in this Law, shall be omitted.

The motion was seconded by Professor MoR#, and was carried, it being recommended
to the Council to take means of ensuring that all existing Members shall benefit by the
change in the entrance fee and annual contribution after ten years, according to their period
of Membership.

Memorandum.—February 2, 1857.—At the Ordinary Meeting of this date, it was an-
nounced from the chair that Mr RussELu desired to be relieved from the office of Treasurer.

The Meeting received Mr RUSSELL’S resignation with the greatest regret ; and resolved
that a cordial acknowledgment of his long continued and zealous services to the Society be
entered on the Minutes.

Memorandum.—February 16, 1857.—At the Ordinary Meeting of this date, Dr
CHRISTISON, V.P., the Chairman, stated that the Council had, according to the recommenda-
tion made at last Meeting, considered the subject of Mr RUSSELL’s retirement, and had re-
solved to propose to the Society the following motions :—

VOL. XXI. PART IV. SP

662 PROCEEDINGS OF STATUTORY GENERAL MEETINGS,

“1, That Mr Russext’s letter of resignation be recorded in the Minutes.”
This motion was unanimously agreed to, and the letter follows :—

Sir,—I have now held the office of Treasurer of the Royal Society for eighteen years, and in the
course of next month I shall enter on the 78th year of my age. It seems to me, therefore, full time
that the duties of that office should be devolved on some younger and more active Fellow of the Society.
I therefore now beg to resign that office, and request you will lay this letter of resignation before the
next Meeting of Council.—I am, &c. (Signed) Joun RusseE.t.

“2, That the following resolution, conveying the thanks of the Society to Mr RussExt, be re-
corded in the Minutes.”
This was carried unanimously, and the resolution follows :—

Resolved, That this Meeting do record their deep sense of the zealous and important services
rendered to the Royal Society by its late Treasurer, Mr Russert. During the long period of eighteen
years for which he has held that office, the funds of the Society have been in a steadily prosperous con-
dition. The benefit of Mr RussEtx’s cordial and effective assistance has been felt not only in this, but
in every department of the Society’s affairs, and that assistance the Meeting hope may still long con-
tinue, notwithstanding Mr Russex.’s withdrawal from the responsibility of his official position.

“3. That Mr James Gisson-Crate be elected Treasurer, in room of Mr Russert resigned.”
This motion was carried unanimously.

Memorandum.— March 2, 1857.,—At the Ordinary Meeting of this date, Mr D.
SMITH made the following motion, which was seconded by Mr NasMyYTH, and unanimously
adopted :-—

“That the Council be requested to consider the propriety of recording in a fitting and permanent
manner the feelings of the Society towards their late Treasurer, Mr Russet, for the benefit which the
Society has received from his attention and exertions during the time he has acted as Treasurer, and to
report their opinion and the manner in which they think such a record should be most appropriately made.”

Memorandum.—April 20, 1857.—At the Ordinary Meeting of this date, Dr FLEMING
moved, and Mr SyME seconded, the following resolutions, of which notice had been given
at the previous Ordinary Meeting :—

“1. That the Council has exceeded its powers in reference to the Neill Prize, by determining and
announcing the conditions of appropriation before submitting the case for the approval of the Society.

“2, That the conditions announced by the Council are framed with the view of enhancing the
importance and promoting the interest of the Society, rather than the recognition of merit, contem-
plated in a liberal spirit, and so unequivocally indicated by the terms of the bequest.

« 3. That the subject be remitted to the Council for reconsideration, with an injunction that the
results be laid before the Society for approval, previous to publication.’

The Rev Dr GRANT moved, and Mr D. SmitTH seconded, the following amendment :—

“That the Society sees no ground for disturbing the arrangements for the appropriation of the
Neill Bequest, as announced by the Council, and expresses its approval of said arrangements.”

On the vote being taken, 32 voted for the amendment, and 18 for the motion.

The Chairman declared the amendment to be carried.

Memorandum.—April 20, 1857.—At the Ordinary Meeting of this date, it was pro-
posed on the part of the Council (in consequence of a remit to them from the Society on the
2d March), that a sum not exceeding Fifty Guineas, should be set apart from the funds of the
Society for the purchase of a piece of Plate to be presented to Mr RUSSELL, the late Trea-
surer, in the name of the Society, and in acknowledgment of his long-continued and valuable
services ; a notice to this effect having been made at last Ordinary Meeting.

This motion was carried by acclamation.

a eee

AND LIST OF MEMBERS ELECTED.

MEMBERS ELECTED.

April 18, 1853.
Hveu Scort, Esq. of Gala.

December 5, 1853.

Grame Rep Mercer, Esq.

December 19, 1853.

Dr Georce Burst, Bombay.

January 8, 1854.

Sir Jonn Maxwett, Bart.

January 16, 1854.
Witiiam Murray, Esq. of Monkland.

February 20, 1854.

Dr Joun Appineton Symonps, Clifton, Bristol.

April 3, 1854.

Henry Duntop, Esq. of Craigton.

April 17, 1854.

663

Dr Wittiam Birp HerapatH, Bristol. Professor Ropert Harkness, Queen’s College, Cork.

December 4, 1854.

Dr Tuomas A. WIsz. Dr James Coxe.

December 18, 1854.

ERNEST Bonar, Esq.

January 2, 1855.

James P, Fraser, Esq.

February 5, 1855.

Dr Stevenson Macapam.

February 19, 1855.

Ropert EtueripGe, Hsq., Clifton, Bristol. Joun Inexis, Esq., Dean of Faculty.

Rev, James 8. Hopson, M.A.

March 19, 1855.

Dr Wyvittz T. C. THomson, Professor of Geology, Belfast.

664 LIST OF MEMBERS ELECTED.

April 2, 1855.

Sir Ropert K. Arsurunot, Bart.

April 30, 1855.
Dr Wricut, Cheltenham.

December 3, 1855.
James Hay, Esq. R. M. Suitu, Esq.

January 7, 1856.

Davip Bryce, Esq.

January 21, 1856.

Witriam Mitcnety Extis, Esq. Dr Grorcr J. ALLMAN.

February 4, 1856.

Hon. Lord Nzaves. Dr Freperick Penny.

February 18, 1856.

Dr Tomas Laycock, Professor of Medicine.

March 17, 1856.

Tuomas Crecuorn, Esq., Advocate.

April 21, 1856.
James CLERK Maxwett, Esq., Professor of Natural Philosophy, Marischal College, Aberdeen,

January 5, 1857.

Horatio Ross, Esq. Dr James Brack.

February 2, 1857.

Dr Joun Ivor Murray.

February 16, 1857.
Joun Metvitxe, Esq., W.S. Joun Brackwoop, Esq.

Brinstry Dz Courcy Nixon, Esq.

March 2, 1857.

Anprew Murray, Esq. of Conland. Rev. Dr James MacraRLane, Duddingston.
Dr W. M. Bucwanay.

April 6, 1857.
Tuomas Loetn, Esq., C.E., Pegu.

Date of
Election.

1798
1808

1811

1812

1813
1814

1815

1816

1817

1818

1819

LIST OF THE PRESENT ORDINARY MEMBERS,

IN THE ORDER OF THEIR ELECTION.

General Sir THOMAS M. BRISBANE, Bart., G.C.B., &c., F.R.S. Lond.,
PRESIDENT.

Alexander Monro, M.D.

James Wardrop, Esq., London.

Sir David Brewster, K.H., LL.D., F.R.S., Lond., St Andrews.

General Sir Thomas Makdougall Brisbane, Bart., G.C.B., G.C.H., F.R.S. Lond.
James Jardine, Esq., Civil Engineer.

Alexander Gillespie, Esq., Surgeon.

James Pillans, Esq., Professor of Humanity.

Sir George Clerk, Bart., F.R.S. Lond.

William Somerville, M.D., F.R.S. Lond.

Right Honourable Viscount Arbuthnot.

John Fleming, D.D., Professor of Natural Science, New College.
Henry Home Drummond, Esq., of Blair-Drummond.

William Thomas Brande, Esq., F.R.S. Lond., Professor of Chemistry in the Royal Institution.
Leonard Horner, Esq., F.R.S. Lond.

Alexander Maconochie Wellwood, Esq., of Meadowbank.

William P. Alison, M.D., Emeritus Professor of the Practice of Physic.
Robert Bald, Esq., Civil Engineer.

Patrick Miller, M.D., Ezeter.

John Watson, M.D.

Right Honourable John Hope, Lord Justice-Clerk.

Patrick Murray, Esq., of Simprim.

Thomas Stewart Traill, M.D., Professor of Medical Jurisprudence.
Alexander Adie, Esq.

VOL. XKI. PART Iv. 8 Q

666 LIST OF ORDINARY MEMBERS.

Date of
Election.

1819 George Forbes, Esq.
1820 James Keith, M.D., Surgeon,
Charles Babbage, Esq., F.R.S. Lond.
Sir John F. W. Herschel, Bart., F.R.S. Lond.
John Shank More, Esq., Professor of Scots Law.
Dr William Macdonald, Professor of Natural History, St Andrews.
Sir John Hall, Bart., of Dunglass.
1821 Sir James M. Riddell, Bart., Strontian.
John Lizars, Esq., Surgeon.
John Cay, Esq., Advocate.
Robert Kaye Greville, LL.D.
Robert Hamilton, M.D.
1822 James Smith, Esq. of Jordanhill, F.R.S. Lond.
William Bonar, Esq.
George A. Walker-Arnott, LL.D., Professor of Botany, Glasgow.
Very Rev. John Lee, D.D., Principal of the University of Edinburgh.
Sir James South, F.R.S. Lond.
Sir W. C. Trevelyan, Bart., Wallington, Northumberland.
John Russell, Esq., P.C.S. |
1823 Captain Thomas David Stuart, of the Hon. East India Company’s Service.
Andrew Fyfe, M.D., Professor of Medicine and Chemistry, King’s College, Aberdeen.
Robert Bell, Esq., Advocate.
Admiral Norwich Duff.
Warren Hastings Anderson, Esq.
Alexander Thomson, Esq., of Banchory. |
Liscombe John Curtis, Esq., Ingsdon House, Devonshire.
Robert Christison, M.D., Professor of Materia Medica, |
John Gordon, Esq., of Cairnbulg. .
1824 Robert E. Grant, M.D., Professor of Comparative Anatomy, University College, London.
Rev. Dr William Muir, one of the Ministers of Edinburgh.
James Pillans, Esq.
James Walker, Esq., Civil Engineer.
William Wood, Esq., Surgeon.
1825 Honourable Lord Wood.
1826 Sir David Hunter Blair, Bart., Blairquhan, Ayrshire.
1827 John Gardiner Kinnear, Esq.
James Russell, M.D.
Very Rev. Edward Bannerman Ramsay, A.M., Camb.
1828 Erskine Douglas Sandford, Esq., Advocate.
David Maclagan, M.D.
Sir William A. Maxwell, of Calderwood, Bart.
John Forster, Esq., Architect, Liverpool.
Thomas Graham, A.M., Professor of Chemistry, London Unwwersity.
David Milne Home, Esq., Advocate.

Date of
Election.

1828
1829

1830

1831

1832

1833

1834

1835

1836

1837

LIST OF ORDINARY MEMBERS. 667

Dr Manson, Nottingham.

A. Colyar, Esq.

Sir William Gibson-Craig, Bart., of Riccarton.

Right Honourable Duncan M‘Neill, Lord Justice-General.
Venerable Archdeacon Sinclair, Kensington.

Arthur Connell, Esq., Professor of Chemistry, St Andrews.
James Walker, Esq., W.S.

J. T. Gibson-Craig, Esq., W.S.

Sir Archibald Alison, Bart., Sherif’ of Lanarkshire.
Honourable Mountstuart Elphinstone.

James Syme, Esq., Professor of Clinical Surgery.

Thomas Barnes, M.D., Carlisle.

James D. Forbes, D.C.L., F.R.S. Lond., Professor of Natural Philosophy.
Right Honourable Lord Dunfermline.

David Boswell Reid, M.D., London.

John Sligo, Esq., of Carmyle,

William Gregory, M.D., Professor of Chemistry.

Robert Allan, Esq., Advocate.

Robert Morrieson, Esq., Hon. E.I.C. Civil Service.
Montgomery Robertson, M.D.

Captain Milne, R.N.

His Grace the Duke of Buccleuch, K.G., Dalkeith Palace.
David Craigie, M.D.

Sir John Stuart Forbes, Bart., of Pitsligo.

Alexander Hamilton, LL.B., W.S.

Right Honourable Earl Cathcart.

Mungo Ponton, Esq., W.S., Clifton, Bristol.

Isaac Wilson, M.D., F.R.S. Lond.

Professor Low.

Patrick Boyle Mure Macredie, Esq., Advocate, of Piercetown.
John Davies Morries Stirling, Esq.

Thomas Jameson Torrie, Esq.

John Haldane, Esq., Haddington.

William Sharpey, M.D., Professor of Anatomy, University College, London.
John Hutton Balfour, M.D., A.M., F.R.S. Lond., Professor of Botany.
Right Honourable Lord Campbell.

William Brown, Esq., F.R.U.S.

R. Mayne, Esq.

David Rhind, Esq., Architect.

Archibald Robertson, M.D., F.R.S. Lond.

John Archibald Campbell, Esq., W.S.

John Scott Russell, Esq., A.M , London,

Charles Maclaren, Esq.

Archibald Smith, Esq., M.A., Camb., Lincoln’s Inn, London.

668 LIST OF ORDINARY MEMBERS.

Date of
Election.

1837 Richard Parnell, M.D.

Peter D. Handyside, M.D., F.R.C.S.

1838 Thomas Mansfield, Esq., Accountant.
Alan Stevenson, Esq., Civil Engineer.

1839 David Smith, Esq., W.S.

Adam Hunter, M.D.

Rev. Philip Kelland, A.M., Professor of Mathematics.
William Alexander, Esq., W.S.

F. Brown Douglas, Esq., Advocate.

Colonel Swinburne, of Mearns.

1840 Alan A. Welwood Maconochie, Esq.
Martyn J. Roberts, Esq., Fort-William,
Robert Chambers, Esq.

James Forsyth, Esq., of Dunach.
Sir John M‘Neill, G.C.B.

John Cockburn, Esq.

Sir William Scott, Bart., of Ancrum.
Right Rev. Bishop Terrot.

Edward J. Jackson, Esq.

John Learmonth, Esq., of Dean |
John Mackenzie, Esq.

James Anstruther, Esq., W.S.

1841 John Millar, Esq., Civil Engineer, Millfield House, Polmont.
George Smyttan, M.D.

James Dalmahoy, Esq.

1842 James Thomson, Hsq., Civil Engineer, Milford, Pembrokeshire.
John Davy, M.D., Inspector-General of Army Hospitals.
Robert Nasmyth, Esq., F.R.C.S.

Sir James Forrest, Bart., of Comiston.
James Miller, Esq., Professor of Surgery,
John Goodsir, Hsq.. Professor of Anatomy.
1843 A. D. Maclagan, M.D., F.R.C.S.
John Rose Cormack, M.D., F.R.C.P., Putney.
Allen Thomson, M.D., Professor of Anatomy, Glasgow.
Joseph Mitchell, Esq., Civil Engineer, Inverness.
Andrew Coventry, Esq., Advocate.
John Hughes Bennett, M.D., F.R.C.P., Professor of Physiology.
D. Balfour, Esq., of Trenaby.
Henry Stephens, Esq. :

1844 The Honourable Lord Murray.

J. Burn Murdoch, Esq., Advocate, of Gartincaber.
Archibald Campbell Swinton, Esq., Professor of Civil Law.
James Begbie, M.D., F.R.C.S.

James Y. Simpson, M.D., Professor of Midwifery.

Date of
Election.

1844

1845

1846

1847

1848

1849

LIST OF ORDINARY MEMBERS. 669

David Stevenson, Esq., Civil Engineer.

Thomas R. Colledge, M.D., F.R.C.P.E.

James Andrew, M.D.

George Wilson, M.D., Professor of Technology.

John G. M. Burt, M.D.

Thomas Anderson, M.D., Professor of Chemistry, Glasgow.

A. Taylor, M.D., Pau.

S. A. Pagan, M.D.

Rev. Dr James Robertson, Professor of Divinity and Ecclesiastical History.
Alexander J. Adie, Esq., Civil Engineer.

L. Schmitz, LL.D., Ph.D., Rector of High School.

Charles Piazzi Smyth, Esq., Professor of Practical Astronomy.
George Makgill, Esq., of Kemback.

William Thomson, Hsq., M.A. Camb,, Professor of Natural Philosophy, Glasgow.
J.H. Burton, Esq., Advocate.

James Nicol, Esq., Professor of Natural History, Aberdeen.

William Macdonald Macdonald, Esq., of St Martins.

Honourable Lord Handyside.

Alexander Christie, Esq.

John Wilson, Esq., Professor of Agriculture.

Moses Steven, Hsq., of Bellahouston.

James Tod, Esq., W.S., Secretary to the Royal Scottish Society of Arts.
Thomas Stevenson, Esq., C.E.

James Allan, M.D., Inspector of Hospitals, Portsmouth.

Henry Davidson, Esq.

Patrick Newbigging, M.D.

William Swan, Hsq.

Patrick James Stirling, Esq.

William Stirling, Esq., of Keir, M.P.

John Thomson Gordon, Esq., Sherif? of Mid-Lothian.

D. R. Hay, Esq.

William Thomas Thomson, Esq.

Honourable Lord Ivory.

William HE, Aytoun, D.C.L., Professor of Rhetoric and Belles Lettres.
W. H. Lowe, M.D., Balgreen.

Honourable B, F. Primrose.

John Stenhouse, M.D., Islington.

David Anderson, Esq., of Moredun.

W. R. Pirrie, M.D., Professor of Surgery, Marischal College, Aberdeen.
Right Honourable The Earl of Minto, G.C.B., Minto House.

Right Honourable The Earl of Aberdeen, K.T., Haddo House.

Right Honourable The Earl of Haddington, K.T., Tyningiame.,

His Grace The Duke of Argyll, Inverary Castle.

The Most Noble the Marquis of Tweeddale, K.T,

VOL. XXI. PART IV. SR

670 LIST OF ORDINARY MEMBERS.

Date of
Election.

1849 Edward Sang, Esq.
1850 William John Macquorn Rankine, Esq., C.E., Professor of Civil Engineering, Glasgow
University. ,
Alexander Keith Johnston, Esq.
Sheridan Muspratt, M.D., Liverpool.
James Stark, M.D. (Re-admitted.)
Captain W. Driscoll Gossett, R.E.
William Seller, M.D., F.R.C.P.E.
Hugh Blackburn, Esq., Professor of Mathematics, Glasgow.
R. D. Thomson, M.D., London.
Mortimer Glover, M.D., Newcastle,
Beriah Botfield, Esq., Norton Hall, Northamptonshire.
J.S. Combe, M.D.
1851 Sir David Dundas, Bart., of Dunira.
Sir George Douglas, Bart., of Springwood Park.
John Stewart, Esq., of Nateby Hall.
E. W. Dallas, Esq.
Rev. James Grant, D.C.L., D.D., one of the Ministers of Edinburgh. {
Sir James Ramsay, Bart., Bamf House, Alyth.
1852 Eyre B. Powell, Esq., Madras. :
Thomas Miller, Esq., A.M., LL.D., Rector, Perth Academy.
Allen Dalzell, M.D.
James Cunningham, Esq., W.S.
Alexander James Russell, Esq., C.S.
Andrew Fleming, M.D., Bengal.
1853 James Watson, M.D., Bath.
Capt. Robert Maclagan, Bengal Engineers.
Rev. Dr Robert Lee, Professor of Biblical Criticism and Biblical Antiquities.
James M. Hog, Esq., of Newliston.
Rev. John Cumming, D.D., London.
Hugh Scott, Esq., of Gala.
Greme Reid Mercer, Esq.
Dr George Buist, Bombay.
1854 Sir John Maxwell, Bart., of Polloc.
William Murray, Esq., of Monkland.
Dr John Addington Symonds, Clifton, Bristol.
Henry Dunlop, Esq., of Craigton.
Dr William Bird Herapath, Bristol.
Robert Harkness, Esq., Professor of Mineralogy and Geology, Queen’s College, Cork.
Thomas A. Wise, M.D.
James Coxe, M.D.
Ernest Bonar, Esq.
1855 James P. Fraser, Esq.
Stevenson Macadam, Ph.D.

Date of
Election.

1855

1856

1857

LIST OF ORDINARY MEMBERS. 671

Robert Etheridge, Esq., Clifton, Bristol.

John Inglis, Esq., Dean of Faculty.

Rev. James 8. Hodson, D.D., Oxon., Rector of the Edinburgh Academy.
Wyville T. C. Thomson, LL.D., Professor of Geology, Belfast.
Sir Robert K. Arbuthnot, Bart.

Dr Wright, Cheltenham.

James Hay, Esq.

R. M. Smith, Esq.

David Bryce, Esq.

William Mitchell Ellis, Esq.

George J. Allman, M.D., Professor of Natural History.
Honourable Lord Neaves.

Dr Frederick Penny.

Thomas Laycock, M.D., Professor of the Practice of Medicine.
Thomas Cleghorn, Esq.

James Clerk Maxwell, Esq., Professor of Natural Philosophy, Marischal College, Aberdeen.
Horatio Ross, Esq.

James Black, M.D.

John Ivor Murray, M.D.

John Melville, Esq., W.S.

John Blackwood, Esq.

Brinsley De Courcy Nixon, Esq.

Andrew Murray, Esq., of Conland, W.S.

Reverend Dr James Macfarlane, Duddingston.

W. M. Buchanan, M.D.

Thomas Login, Esq., C.E., Pegu.

( 672 )

LIST OF NON-RESIDENT AND FOREIGN MEMBERS.

ELECTED UNDER THE OLD LAWS.

NON-RESIDENT.
Richard Griffiths, Esq., Civil Engineer.

LIST OF HONORARY FELLOWS.

His Majesty the King of the Belgians.

His Imperial Highness the Archduke John of Austria.
His Imperial Highness the Archduke Maximilian.

His Royal Highness the Prince Consort.

FOREIGNERS (LIMITED TO THIRTY-SIX.)

*_M. Biot, Paris.
* M. de Hammer, Vienna.
* M. de Humboldt, Berlin.
M. Agassiz, United States.
M. Cousin, Paris.
M. Dumas, Do.
M. Charles Dupin, Do.
M. Ehrenberg, Berlin.
M. Elie de Beaumont, Paris.
M. Encke, Berlin.
M. Flourens, Paris.
M. Guizot, Do.
M. Haidinger, Vienna.
M. Hansteen, Christiania.
M. Hausmann, Gottingen.
M. Lamont, Munich.
M. Leverrier, Paris.

N.B.—The three names marked thus * in the preceding list, were included in the original Honorary List prior to
the change of the Law distinguishing British Subjects from Foreigners,

LIST OF HONORARY FELLOWS.

M. Liebig,

Dr Von Martius,

. Milne-Edwards,
. Mitscherlich,
M. Miller,
M. Necker,
M. Plana,
M
M

M
M

. Quetelet,
. Regnault,
Prof. Henry D. Rogers,
M. Gustav Rose,
M. Studer,
M. Struve,
M. Thenard,
M. Tiedemann,

Munich.

Do.
Paris.
Berlin.

Do.
Geneva.
Turin.

Brussels.
Paris.
Pennsylvania,
Berlin.
Berne.
Pulkowa.
Paris.

i erdelberg.

BRITISH SUBJECTS (LIMITED TO TWENTY, BY LAW x.)

J.C. Adams, Esq.,

G. B. Airy, Esq.,

Robert Brown, Esq.,

Dr Faraday,

Thomas Graham, Ksq.,
Henry Hallam, Esq.,

Sir W. R. Hamilton,

Sir John F, W. Herschel, Bart.,
Sir William J. Hooker,

W. Lassell, Esq.,

Rev. Dr Lloyd,

Sir Charles Lyell,

Sir Roderick I. Murchison,
Richard Owen, Esq.,

Sir John Richardson, M.D.,
Earl of Rosse,

Robert Stephenson, Esq.,
Rev. Dr Whewell,

VOL. XXI. PART IV.

Cambridge.
Greenwich.
London.

Do.

Do.

Do.
Dublin.
Collingwood.
Kew.
Liverpool.
Dublin.
London.

Do.

Do.
Lancrig, Westmoreland.
Parsonstown.
London.
Cambridge.

673

( 674 )

LIST OF FELLOWS DECEASED, RESIGNED, AND CANCELLED

FROM SEPTEMBER 1853 to Aueusr 1857.

HONORARY FELLOWS DECEASED.

M. Arago, Paris.

M. de Bernstein, Berlin.
M, Gauss, Gottingen.

M. Melloni, Naples.

Sir John Franklin, London.
Sir W. E. Parry, Do.

M. Cauchy, Paris,

M. de Charpentier, Bex,
M. Degerando,

ORDINARY FELLOWS DECEASED.

Robert Jameson, Esq., Professor of Natural History:

John Campbell, Esq., of Carbrook,

J. G. Children, Esq., F.R.S.

W. A. Cadell, Esq., F.R.S.

Alexander Brunton, D.D.

Honourable Lord Fullarton.

John Wilson, Esq., late Professor of Moral Philosophy.
Robert Richardson, M.D., Harrowgate.

Richard Philips, Esq., F-R.S.

Rev. Dr William Scoresby, Eweter.

Robert Haldane, D.D., Principal of St Mary’s College, St Andrews.
Sir George Ballingail, M.D., Professor of Military Surgery.
Archibald Bell, Esq., Advocate.

John Clerk Maxwell, Esq., Advocate,

Lieutenant-General Martin White.

Walter Frederick Campbell, Esq.

Sir Robert Abercromby, Bart., of Birkenbog.

Dr Wallich, Calcutta,

John Dewar, Esq., Advocate,

Sir Edward Ffrench Bromhead, Bart., A.M., F.R.S., Thurlsby Hall.
Alexander Wilson Philip, M.D., London.

W. H. Playfair, Esq., Architect.

John Argyle Robertson, Esq., Surgeon.

LIST OF FELLOWS DECEASED, RESIGNED, AND CANCELLED.

Dr John Maewhirter.

Rev. Dr Robert Gordon, one of the Ministers of Edinburgh,
James Wilson, Esq.

George Swinton, Esq.

William Burn Callander, Esq., of Prestonhall,
James Ewing, LL.D., Glasgow.

Bindon Blood, Esq., M.R.I.A.

William Bald, Esq., M.R.I.A.

James L’Amy, Esq., Sherif of Forfarshire.
Donald Smith, Esq.

O. Tyndal Bruce, Esq., of Falkland.

James F, W. Johnston, A.M., Professor of Chemistry in the University of Durham.

John Adie, Esq.

William Murray, Esq., of Henderland.

George Turnbull, Esq.

David Gray, Esq., Professor of Natural Philosophy, Marischal College, Aberdeen.
Right Honourable Lord Rutherfurd.

Honourable Lord Anderson.

Alexander Kemp, Esq.

Colonel Edward Madden.

Dr Marshall Hall.

RESIGNATIONS.

Arthur Forbes, Esq., of Culloden.

Rev. John Hannah, D.C.L., late Rector of Edinburgh Academy.
Rev. Francis Garden.

Rev. A. Barry, Glenalmond.

James W. Grant, Esq., of Elchies.

John 8. Blackie, Esq., M.A., Professor of Greek.

Right Rev. Bishop Trower, D.D.

ELECTION CANCELLED.

Duncan Davidson, Esq., of Tulloch.

675

(

The following Public Institutions and Individuals are entitled to receive Copies of the

676

)

Transactions and Proceedings of the Royal Society of Edinburgh :—

ENGLAND.
The British Museum.
The Bodleian Library, Oxford.
The University Library, Cambridge.

The Roval Society.
The Linnean Society.

The Society for the Encouragement of Arts.

The Geological Society.

The Royal Astronomical Society.
The Royal Asiatic Society.

The Zoological Society.

The Royal Society of Literature.

The Horticultural Society.

The Royal Institution.

The Royal Geographical Society.

The Statistical Society.

The Institution of Civil Engineers.
The Institute of British Architects.
The Ordnance Geological Survey.
The Hydrographical Office, Admiralty.
The Medico-Chirurgical Society.

The Atheneum Club.

The Cambridge Philosophical Society.

The Manchester Literary and Philosophical

Society.
The Yorkshire Philosophical Society.
The Chemical Society of London.
The Museum of Economic Geology.
The United Service Institution.
The Royal Observatory, Greenwich.

The Leeds Philosophical and Literary Society.
The Historic Society of Lancashire and Cheshire.

The Royal College of Surgeons of England.

SCOTLAND.
Edinburgh, University Library.
... Advocates’ Library.

Edinburgh, College of Physicians.

Highland and Agricultural Society.

Royal Medical Society.
Royal Physical Society.
Royal Scottish Society of Arts.

‘Glasgow, University Library.

St Andrews, University Library.
Aberdeen, Library of King’s College.

IRELAND.

The Library of Trinity College, Dublin.
The Royal Irish Academy.

COLONIES, Xe.

The Asiatic Society of Calcutta.

The Literary and Historical Society of Toronto.

CONTINENT OF EUROPE.
Amsterdam, Royal Institute of Holland.
Berlin, Royal Academy of Sciences.

Physical Society.

Berne, Society of Swiss Naturalists.
Bologna, Academy of Sciences.
Bonn, Cesarean Academy of Naturalists.
Brussels, Royal Academy of Sciences.
Buda, Literary Society of Hungary.
Copenhagen, Royal Academy of Sciences.
Frankfort, the Senkenbergian Museum.
Geneva, Natural History Society.
Giessen, University Library.
Gottingen, University Library.
Haarlem, Natural History Society.
Leipzig, Royal Saxon Academy.
Lille, Royal Society of Sciences.
Lisbon, Royal Academy of Sciences.
Lyons, Agricultural Society.
Milan, Royal Institute.

(te e7arn)

Moscow, Imperial Academy of Naturalists.
Munich, Royal Academy of Sciences of Bavaria
(2 copies).
Neufchatel, Museum of Natural History.
Paris, Royal Academy of Sciences.
++» Geographical Society.
+» Royal Society of Agriculture.
Society for Encouragement of Industry.
Geological Society of France.
Ecole des Mines,
Marine Depét.
... Museum of Jardin des Plantes.
Rotterdam, Batavian Society of Experimental
Philosophy.
Stockholm, Royal Academy of Sciences.

St Petersburg, Imperial Academy of Sciences.
M. Kupffer.
Pulkowa Observatory.
Turin, Royal Academy of Sciences.
M. Michelotti.
Venice, Royal Institute.

UNITED STATES OF AMERICA.
Boston, the Bowditch Library.
New York State Library.
Philadelphia, American Philosophical Society.
Yale College, Professor Silliman.
Washington, the Smithsonian Institution.

(All the Honorary and Ordinary Fellows of the Society
are entitled to the Transactions and Proceedings.)

The following Institutions and Individuals receive the Proceedings only :—

ENGLAND.

The Scarborough Philosophical Society.
The Whitby Philosophical Society.
The Newcastle Philosophical Society.
The Geological Society of Cornwall.
The Ashmolean Society of Oxford.
The Literary and Philosophical Society of Liver-
pool.
SCOTLAND.
The Philosophical Society of Glasgow.

VOL. XXI. PART IV.

COLONIES.

The Literary and Philosophical Society of Quebec.

CONTINENT OF EUROPE.

Utrecht, the Literary and Philosophical Society.
UNITED STATES.

Professor Dana, Connecticut.
Academy of Natural Science, Philadelphia.

8T

( 678) )

LIST OF DONATIONS.

(Continued from Vol. XX. p. 663.)

December 5, 1858.

DONATIONS.

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Abhandlungen der Philosoph-Philologischen Classe der Konig], Bayerischen Aka-
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Ditto,
The Academy.

The Observatory.

The Author.
The Institute.

The Academy.
Ditto.
The Society.

Ditto.
The Editors.

The Society.
Ditto,

The Institute.
The Society.

The Editor.

680 LIST OF DONATIONS.

DONATIONS.

Bulletins de ’ Academie Royale des Sciences, des Lettres et des Beaux Arts de
Belgique. Tomexx. 8vo.

Flora Batava. 174 Aflevering. 4to.

Mémoires Couronnées et Mémoires des Savants Etrangers, publiés par l’ Académie
Royale des Sciences de Belgique. Tome v. 2% Partie. 8vo. Two copies.

Memorie della Accademia delle Scienze dell’ Istituto di Bologna. Tome iii. 4to.

Acta Societatis Scientiarum Fennicz. Tom. iii., Fasciculus2. 4to.

Notiser ur Sallskapets pro Fauna et Flora Fennica Forhandlingar. Pt. 2. 4to.

Rendiconto delle Sessioni dell’ Accademia delle Scienze dell’ Istituto di Bologna.
1851-2. 8vo. .

Mémoires de ’Académie Royale des Sciences, des Lettres, et des Beaux Arts de
Belgique. Tome xxvii. 4to.

Mémoires sur les Variations Périodiques et non Périodiques de la Témpérature.
Par A. Quételet. 4to.

Observations de Phénoménes Periodiques. Par A. Quételet. 4to.

Mémoires de la Société des Sciences Naturelles de Cherbourg. 1 Vol. 2° Liv.

8yo.
A History of the Fishes of Massachusetts. By David Humphreys Storer, M.D.,
A.AS. 4to.

Maritime Conference, held at Brussels, for devising an uniform System of Meteoro-
logical Observations at Sea, August and September 1853. to.

March 20, 1854.

The Quarterly Journal of the Geological Society. Vol. x., Part 1. 8vo.

Journal of the Statistical Society of London, Vol. xvii., Part 1. 8vo.

Journal of the Royal Geographical Society. Vol. xxiv. 8vo,

General Index to the Second Ten Volumes of the Journal of the Royal Geogra-
phical Society. 8vo.

Proceedings of the Literary and Philosophical Society of Liverpool. 1851-3.
No. 7. 8vo.

A Collection of Tables, Astronomical, Meteorological, and Magnetical. By Lieut.-
Colonel J. T. Boileau. 4to. 5 Copies.

Mémoires de I’ Academie Nationale des Sciences, Belles Lettres, et Arts de Lyon,
Classe des Lettres. Tome 1°. 8vo.

Mémoires de ]’Academie Nationale des Sciences, Belles Lettres, et Arts de Lyon.
Classe des Sciences. Tome 1, 8vo.

April 3, 1854,

Smithsonian Contributions to Knowledge. Vol. v. 4to.
Sixth Annual Report of the Board of Regents of the Smithsonian Institution for
the year 1851. 8vo.
Smithsonian Institution Meteorological Tables. Prepared by Arnold Guyot. 8vo.,
Portraits of North American Indians. With Sketches of Scenery, &c. Painted
by J. M. Stanley. Deposited with the Smithsonian Institution. 8vo,
Catalogue of North American Reptiles in the Museum of the Smithsonian In-
stitution, 8vo,

Owen’s Geological Survey of Wisconsin, Iowa, and Minnesota. With Illustra-
tions. Ato.

Schooleraft’s History of the Indian Tribes of the United States. Part 3. 4to.

Memoirs and Maps of California. By Ringgold. 8vo.

Stanbury’s Expedition to the Great Salt Lake, 8vo. With Maps.

Report on the Geology of the Lake Superior Land District. By J. W. Foster
and J. D. Whitney. Part2. 8vo. With Maps.

DONORS.
The Academy.

King of Holland.
The Academy,

Ditto.
The Society,

Ditto.
The Academy.

Ditto.
The Author.

Ditto.
The Society.

The Author.

The Belgian
Academy.

The Society.
Ditto.
Ditto.
Ditto.

Ditto.

The Directors of
Hon. E.1.C.
The Academy,

Ditto.

The Institution.
Ditto. ;

Ditto. |
Ditto.

Ditto.

The American
Government.
Ditto.
Ditto.
Ditto.
Ditto.

LIST OF DONATIONS.

DONATIONS.

Official Report of the United States Expedition to explore the Dead Sea and the
River Jordan. By Lieut. W. F. Lynch, U.S.N. 4to.

Boston Journal of Natural History, containing Papers and Communications read
before the Boston Society of Natural History. Vol. vi., Nos. 1 and 2. 8vo,

Bulletin de la Société Imperiale des Naturalistes de Moscou. 1851, Nos. 3
& 4; 1852, Nos. 1. 8vo.

Bulletin de la Société de Géographie. 4'°™° Série. Tomes iv. & y.

Jahrbuch der Kaiserlich-Kéniglichen Geologischen Reichsanstalt.
Jahrgang. 1853, iv. Jahrgang. 8vo.

Flora Batava. 173 Aflevering. 4to.

Stellarum Fixarum imprimis duplicium et multiplicium positiones medie pro
epocha 1830,0. Auctore F, G. W. Struve. Fol.

Mémoire sur les Ouragans de la Mer des Indes, au sud de I’ Equateur.
A. Lefebre. 8vo.

Considérations générales sur l’Océan Pacifique pour fair suite a celles sur l’Océan
Atlantique et sur l’Océan Indien. Par M. Charles P. de Kerhallet. 8vo.

Tableau général des Phares et Fanaux des Cotes de la Méditerranée, de la Mer
Noire, et de la Mer d’Azof. 8vo.

Abhandlungen der Mathemat. Physikalischen Classe der Koeniglich Bayer-
ischen Akademie der Wissenschaften. Bd. vii., 1 Abth. 4to.

Annalen der Kéniglichen Sternwarte bei Miinchen. V. Bd. 8vo,

Jahres Bericht der Miinchener Sternwarte fiir 1852. 8vo.

Afrika vor den Entdeekungen der Portugiesen. Von Dr Friedrick Kuntsmann, 4to.
Studien des Gottingischen Vereins Bergminnischer Freunde. Im namen desselben
herausgegeben von J. F. L, Hausmann. Bd. xvi. Heft. 1&2. 8vo.
Nachrichten von der Georg-Augusts Universitat und der Konig]. Gesellschaft der

8vo.
1852, in.

Par M.

Wissenschaften zu Gottingen. 1852. 12mo.
May 1, 1854.
Archives du Muséum d’Histoire Naturelle. Publiées par les Professeurs de cet
établissement. Tome vii, Liv, 1 et 2. 4to.
Actuarial Tables ; Carlisle Three-per-Cent. Single Lives and Single Deaths. With
Auxiliary Tables. By William Thomas Thomson, F.R.S.E., F.I.A. 4to.
On the application of Cast and Wrought Iron for Building Purposes. By William
Fairbairn, C.E. 8vo.
Jahrbuch der Kaiserlich Kéniglichen Geologischen Reichsanstalt. 1853. _ iv.

Jahrgang. 8vo.
Denkschriften der Kaiserlichen Akademie der Wissenschaften.
turwissenschaftliche Classe. Band vi. 4to.
Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften.
Naturwissenschaftliche Classe. Band xi. 8vo.
Mémoires de ]’Académie de Sciences de l'Institut de France. Tome xxiv. 4to.
Memoirs of the Geological Survey of the United Kingdom. British Organic Re-
mains. Parts 1, 2, 3,4,6,7. 4to.
Memoirs of the Geological Survey of Great Britain, and of the Museum of Practical
Geology in London. Vol. ii., Parts 1 and 2. 8vo.
Museum of Practical Geology and Geological Survey.

Mathematisch-Na-

Mathematisch-

Records of the School of

Mines and of Science applied to the Arts. Parts 1, 2, 3, 4. 8vo. (With
various Maps and Pamphlets).

Journal of the Geological Society of Dublin. Vol. vi., Part 1. 8vo.

The Assurance Magazine, and Journal of the Institute of Actuaries, Vol. iv.,

Part 3. 8vo.
Silliman’s American Journal of Science and Arts. Vol. xvii., No. 50. 8vo.
Comptes Rendus hebdomadaires des Séances de l’Académie des Sciences.
1853-Mai 1854. 4to.
VOL. XXI. PART IV.

Mai

681

DONORS.

The American
Government.

The Editors.

The Society,

Ditto.
The Institute.

King of Holland.
The Russian
Government.
Depot Général
de la Marine.
Ditto.

Ditto.
The Academy.

The Observatory.
Ditto.

_ The Author.

The Society.

Ditto.

The Museum.
The Author.
Ditto.
The Institute.
The Academy.
Ditto.
Ditto.

H. M. Govern-
ment,
Ditto.
Ditto.

The Society.

The Institute.

The Editors.
The Academy.

8U

682 LIST OF DONATIONS.

DONATIONS.

Memorie della Reale Accademia delle Scienze di Torino. Tom. xiii. 4to.
Bulletins de la Société de Géographie. Tome v. 8vo.
Annales de l’Agriculture et de l’Industrie de Lyon. Tome iii. 8vo.
Annales de l'Observatoire Physique Central de Russie. 1851. 2 Tomes. 4to,
Journal of the Horticultural Society of London. Vol. viii., Part 4. 8vo.

December 4, 1854.
Journal of the Royal Asiatic Society of Great Britain and Ireland. Vol. xvi.,

Part 1.

8vo.

A Descriptive Catalogue of the Historical Manuscripts in the Arabic and Persian ~

Languages, preserved in the Library of the Royal Asiatic Society of Great
Britain and Ireland. By William H. Morley, M.R.A.S. 8vo.

Essay on the Architecture of the Hindis. By Ram Raz. Published for the
Royal Asiatic Society of Great Britain and Ireland. 4to.

Jahrbuch der Kaiserlich-K6niglichen Geologischen Reichsanstalt.
gang. Nt 4. October, November, December. 8vo.

Mémoires de l’Académie Impériale des Sciences, Belles Lettres et Arts de Lyon.
Classe des Lettres. Tome ii. 8vo.

Mémoires de |’Académie Impériale des Sciences, Belles Lettres et Arts de Lyon.
Classe des Sciences. Tome ii. 8vo.

Annales des Sciences Physiques et Naturelles d’Agriculture et d’Industrie, pub-
liées par la Société Impériale d’Agriculture, &c., de Lyon. 2™* Série. Tome
iv. 1852. 8vo.

Mémoires présentés par divers savants 4 l’Académie des Sciences de I’Institut Im-
périal de France, et imprimés par son ordre. Sciences Mathématiques et Phy-
siques. Tome xii. 4to.

Natuurkundige Verhandelingen van de Hollandsche Maatschappij der Wetenschappen
te Haarlem. Tweede Versameling. 4°, 9%°, 10%, 11° Deel, 1° Stuk. 4to.

Philosophical Transactions of the Royal Society of onda. 1852, Parts 1 and 2;
18538, Parts 1, 2,3; 1854, Part 1. 4to.

1853. iv. Jahr-

Verhandelingen der Koninklijke Akademie van Wetenschappen te Amsterdam. 15
Deel. 4to.
Det Kongelike Danske Videnskabernes Selskabs Skrifter. Femfte Reeke. Natur-

videnskabelig og Mathematisk Afdeling. B43. 4to.

Abhandlungen, herausgegeben von der Senckenbergischen Naturforschenden Gesell-
schatt. 1° B4 1° Lieferung. 4to.

Astronomical and Magnetical ad Meteorological Observations made at te Royal
Observatory, Greenwich, in the year 1852. 4to.

Natural History of New York. Paleontology of New York. By James =
Vols. i. and ii. 4to.

Agriculture of New York. By Ebenezer Emmons, M.D. Vols. i., ii.,
and iii. 4to.

Magnetical and Meteorological Observations made at the Honourable East India Com-
pany’s Observatory, Bombay, in the year 1850. 4to.

Astronomical. Observations made at the Observatory of Cambridge.
1846, 1847, and 1848.

Mémoires Couronnés et Mémoires des Savants étrangers publiées par |’ Académie
Royale des Sciences, des Lettres et des Beaux Arts de Belgique. Tome xxv.
1851-53. 4to:

Annales de Observatoire Royal de Bruxelles. Tome x. 4to.

Compte rendu des Travaux du Congrés Général de Statistique, réuni 4 Bruxelles, les
19, 20, 21 et 22 Septembre 1853, Par A. Quételet. 4to.

Mémoires de la Société de Physique et d’Histoire Naturelle de Genéve.
Qme Partie. to.

Denkschriften der Kaiserlichen Akademie der Wissenschaften.
Naturwissenschaftliche Classe. B%. 7. 4to.

Vol. xvii., for

Tome xiii.,

Mathematisch-

DONORS.

The Academy.

The Society.
Ditto.

The Observatory.

The Society.

The Society.

Ditto.

Ditto.
The Institute.
The Society.
Ditto.

Ditto.
The Institute,

The Society.
Ditto.
The Academy.
The Society.
Ditto.
The Royal So-
ciety.
The State of New
York.
Ditto.
The Hon. East
India Company.
The Observatory.
The Academy.
The Observatory.
The Author.
The Society.

The Academy.

LIST OF DONATIONS.

DONATIONS.
Tables du Soleil exécutées d’aprés les ordres de la Société Royale des Sciences de
Copenhague, par MM. P. A. Hansen et C. F. R. Olufsen. 4to.
Rendiconto della Societa Reale Borbonica. Accademia delle Scienze. N.S. N's

4&5. 4to.

Atti della Reale Accademia delle Scienze, sezione della Societa Reale Borbonica.
Vol. vi. to.

Transactions of the American Philosophical Society, held at Philadelphia, (N.S.)
Vol. x., Part 3. 4to.

Proceedings of the American Philosophical Society. Vol. v., No. 50. 8vo.

Researches upon Nemerteans and Planarians.
development of Planocera elliptica. 4to.

Notes on new species and localities of Microscopical Organisms, By J. W. Bailey,
M.D. 4to.

Smithsonian Contributions to Knowledge. Vol. vi. 4to.

Catalogue of the described Coleoptera of the United States.
Melsheimer, M.D. 8vo.

Seventh Annual Report of the Board of Regents of the Smithsonian Institution.
1853. 8vo.

The Annular Eclipse of May 26, 1854. Published under the authority of Hon.
James C. Dobbin, Secretary of the Navy, by the Smithsonian Institution.

Astronomical Observations made during the year 1847 at the National Observatory,

By Charles Girard. 1. Embryonic

By Frederick Ernest

Washington. Vol. iii. 4to.
Patent Office Reports, published by the State of Washington. 1851-3. 3 vols.
8vo.

Transactions of the Wisconsin State Agricultural Society. 1851 and 1852. 8vo.

Medico-Chirurgical Transactions. Published by the Royal Medical and Chirurgical
Society of London. Vol. xxxvii. 8vo.

The Philosophy of Physics, or Process of Creative Development.
Brown. 8vo.

Bulletin de la Société Impériale des Naturalistes de Moscou.
4, 1853, N= 1&2. 8vo.

Novorum Actorum Academiz Czsareze Leopoldino-Caroline Nature Curiosorum.
Vol. xxiv. Pars 1. 4to.

Abhandlungen der Kéniglichen Akademie der Wissenschaften zu Berlin. 1853. 4to.

Monatsbericht der Konig]. Preuss, Akademie der Wissenschaften zu Berlin, August
1853—Juli 1854. 8vo.

Nachrichten von der Georg-Augusts-Universitat und der Konigl. Gesellschaft der
Wissenschaften zu Gottingen. 1853. 12mo.

Studien des Géttingischen Vereins Bergmannischer Freunde. In namen desselben
herausgegeben von J. F. L. Hausmann. B41, heft 8. 8vo.

Siluria. The History of the oldest known Rocks containing Organic Remains, with
a brief Sketch of the distribution of Gold over the Earth. By Sir R. I. Mur-
chison. 8vo.

Museum of Practical Geology and Geological Survey. Records of the School of
Mines and of Science applied to the Arts. Vol. i, Part 4. 8vo.

The Journal of Agriculture, and Transactions of the Highland and Agricultural
Society of Scotland. N.S., Nos. 45 and 46. 8vo.

Proceedings of the Architectural Institute of Scotland. Session 1853-54. 8vo.

Twenty-first Annual Report of the Royal Cornwall Polytechnic Society. 1853. 8vo.

Journal of the Statistical Society of London. Vol. xvii, Part 2. 8vo.

The Assurance Magazine, and Journal of the Institute of Actuaries, Vol. v., Part
4; and Vol. v., Part 1. 8vo.

By Andrew

1852, N 2, 3, &

List of Members of the Institute of Actuaries of Great Britain and Ireland. 1854-5.
8vo.
Atheneum. Rules and Regulations, Lists of Members, and Donations to the Li-

brary, 1852, with Supplement for 1853. 12mo.

683

DONORS.
The Society.

Ditto.
Ditto:
Ditto.

Ditto.
The Author.

The Smithsonian
Institution.
Ditto.
Ditto.
Ditto.
Ditto. |
The Observatory.
The Government
of Washington.
The Society.
Ditto.
The Author,
The Society.
The Academy.

Ditto.
Ditto.

The Society.
The Editor.

The Author.

The Museum.

The Society.

The Institute.

The Society.
Ditto.
Ditto.

The Institute.

The Athenzum,

684 LIST OF DONATIONS.

December 18, 1854.

DONATIONS.

Archzologia; or, Miscellaneous Tracts relating to Antiquity, published by the
Society of Antiquaries of London. Vols. xxxii., xxxiii., xxxiv., xxxv. 4to,

Proceedings of the Society of Antiquaries of London. Vols. i., ii,; Vol. iii.,
Nos. 37-40. 8vo.

Catalogue of Roman Coins collected by the late Rev. Thomas Kerrich, M.A., F.S.A.,
Prebendary of Wells and Lincoln, and presented by his Son, the Rev.
Richard Edward Kerrich, M.A., F.S.A., to the Society of Antiquaries of Lon-
don. 8vo.

List of the Society of Antiquaries of London on 23d April 1854. 8vo.

Memorie della Academia delle Scienze dell’ Istituto di Bologna. Tomo iy. 4to.

Neue Denkschriften der Allgemeinen Schweizerischen Gesellschaft fiir die gesammten
Naturwissenschaften, Band xiii. 4to.

Actes de la Société Helvétique des Sciences Naturelles. Réunie a Sion, les 17,
18, et 19 Adut 1852. 8vo.

Actes de la Société Helvétique des Sciences Naturelles. Réunie 4 Porrentray, les
2, 3, et 4 Adut 1853. 8vo.

Mittheilungen der Naturforschenden Gesellschaft in Bern, N** 268-313. 8vo.

Ueber die Symmetrische Verzweigungsweise dichotomer Inflorescenzen. Von H.
Wydler. 8vo.

Abhandlungen der Historischen Classe der Kéniglich Bayerischen Akademie der
Wissenschaften. B* 7, 15 Abtheil. 4to.

Gelehrte Anzeigen herausgegeben von Mitgliedern der K. Bayerischen Akademie der
Wissenschaften. Ba 36,37. 4to.

Bulletin de la Société de Géographie. 4™° Serie. Tome vii., 8yo.

Bulletins de Académie Royale des Sciences, des Lettres, et des Beaux Arts de
Belgique. Tome xx., 3° Parte; Tome xxi., 1° Parte. Annexe aux Bulletins,
1853-4. 8vo.

Transactions of the Pathological Society of London. Vol. v. 8vo.

' Proceedings of the Literary and Philosophical Society of Liverpool, during the 43d
Session, 1858-54. No.8. 8vo.

The American Journal of Scienceand Arts. Conducted by Professors Silliman and
Dana. Vol. xviii. Nos. 52, 538,54. 8vo.

The Quarterly Journal of the Geological Society. Vol. ix., Part 1; Vol. x,
Parts 2 and 3. 8vo.

Jahrbuch der Kaiserlich-K6niglichen Geologischen Reichsanstalt. 1854. No, 1,
Jan. Feb. Marz. 8vo.

Rendiconto della Societa Reale Borbonica. Accademia delle Scienze. N.S. Jan.
June 1853. 4to.

Repertorio Italiano per la Storia. Naturale. Repertorium Italicum complectens
Zoologiam, Mineralogiam, Geologiam, et Palzontologiam, Cura J. Josephi
Bianconi. Vol.i. 8vo.

Jahresbericht tiber die Fortschritte der reinen, Pharmaceutischen und Technischen
Chemie, Physik, Mineralogie und Geologie, herausgegeben von Justus Liebig
& Hermann Kopp. 1853. 8vo.

Universalité dei mezzi di previdenzi, difesa, e salvezza per le calamita deg!’ incendi
opera premiata in concorso dalla Accademia delle Scienze dell’ Istituto di
Bologna. Scritta da Francisco del Guidice. 8vo.

Bulletins de la Société Vaudoise des Sciences Naturelles. Tome iii. Nos. 25,
28, 30, 31, 32. 8vo.

Proceedings of the Academy of Natural Science of Philadelphia. Vol. iii., Nos.
3-6. 8vo.

Notices of the Meetings of the Members of the Royal Institution of Great Britain.
Part 4. Nov. 1853—July 1854. 8vo.

DONORS.
The Society.

Ditto.

Ditto.

Ditto.
The Academy.
The Society,
Ditto.
Ditto.

Ditto.
Ditto.

The Academy.
Ditto.

The Society.

The Academy.

The Society.
Ditto.

The Editors.

The Society.

The Institute.

The Society.

The Author.

The Editors.

The Author.-

The Society,
Ditto.

Ditto.

LIST OF DONATIONS.

DONATIONS.

Report of the Commissioner of Patents for the year 1853.
tures.

Seventh Annual Report of the Board of Regents of the Smithsonian Institution for

_ the year 1852. 8vo.

Exploration of the Valley of the Amazon, made under the direction of the Navy
Department. By William Lewis Herndon and Lardner Gibbon. Parti, By
Lieut. Herndon.

Transactions of the Cambridge Philosophical Society. Vol. i., Part 3.

Journal of the Statistical Society of London. Vol. xvi, Part 3. 8vo.

General Index to the first fifteen volumes of the Journal of the Statistical Society
of London. 8vo.

Part i., Manufac-

Ato.

List of Fellows of the Statistical Society of London. Session 1854-1855. 8vo.

Memoirs of the Royal Astronomical Society. Vol. xxii. 4to.

Journal of the Horticultural Society of London. Vol. ix., Parts 2 and 3. 8vo.

Journal of the Asiatic Society of Bengal. Edited by the Secretaries. Nos. 237-
242. 8vo.

Mémoires de la Société Impériale des Sciences de l’ Agriculture et des Arts de Lille.
1853. 8vo.

Die Fortschritte der Physik in den Jahren 1850 und 1851. Dargestellt von den
Physikalischen Gesellschaft zu Berlin. 6 & 7 Jahrgang. 1° Abtheil. 8vo.

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch-
Naturwissenschaftliche Classe. B4°. xi. und xii. 8vo.

Address to the Boston Society of Natural History. By John C. Warren, M.D. 8vo,

Monthly Notices of the Royal Astronomical Society. Vol. xiii., 1852-3. 8vo.

The American Journal of Science and Arts. Conducted by Professors Silliman and
Dana. Vol. xvii.. No. 51. 8vo.

January 2, 1855.

Flora Batava. 176 Aflevering, 4to.

Transactions of the Architectural Institute of Scotland. Vol. iti., Part 1.

Annalen der Kéniglichen Sternwarte bei Miinchen. 6 Band. 8vo.

Magnetische Ortsbestimmungen ausgefiihrt an verschiedenen Puncten des Konig-
reichs Bayern und an einigen auswartigen Stationen. Von Dr J. Lamont.
1: Theil. 8vo.

Journal of Agriculture, and Transactions of the Highland and Agricultural Society
of Scotland. N.S., No. 47. 8vo.

Almanaque Nautico para el aiio 1855.

8vo.

(San Fernando.) 8vo.

Jahrbuch der Kaiserlich-Koniglichen Geologischen Reichsanstalt 1853.
(Juli, August, September.) 8vo.

Transactions of the Royal Scottish Society of Arts, Vol. iv., Part 2.

Proceedings of the Royal Society. Vol. vi., Nos. 91-101. 8vo.

Boston Journal of Natural History, containing Papers and Communications read
before the Boston Society of Natural History, and published by their direc-

No. 3.

8vo.

tion. Vol. vi., No. 3. 8vo.

Proceedings of the Boston Society of Natural History. Jan. 1, 1851—Nov. 16,
1853. 8vo.

Proceedings of the American Academy of Arts and Sciences. Vol. iii., pp. 1-104.
8yo.

March 5, 1855.

Journal of the Asiatic Society of Bengal. No. 5, 1854. 8vo.
The Quarterly Journal of the Geological Society. Vol. x., Part 4. 8vo.
VOL. XXI. PART IV.

685

DONORS.
Government of
Washington, U.S.
The Institution.

The Author.

The Society.
Ditto.
Ditto.

Ditto.
Ditto.
Ditto.
Ditto.

Ditto.
Ditto.
The Academy.
The Author.

The Society.
The Editors.

King of Holland.

The Institute.

The Observatory.
Ditto.

The Society.
The Observatory
of San Fernando.
The Institute.
The Society.

Ditto.

Ditto.

Ditto.

The Academy.

The Society.
Ditto.
8x

686 LIST OF DONATIONS.

DONATIONS.
Journal of the Statistical Society of London. Vol. xvii., Part 4. 8vo.
The Journal of Agriculture, and Transactions of the Highland and Agricultural
Society of Scotland. N.S. No. 48. 8vo.
Catalogue of Stars near the Ecliptic, observed at Markree, during the years 1852,
18538, and 1854, and whose places are supposed to be hitherto unpublished.
Vol. iii. 8vo.
The American Journal of Science and Arts.
Dana. Vol. xix., No. 55. 8vo.
Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch-
Naturwissenschaftliche Classe. Bd. xii, Heft 5; Bd. xii, Heft 1 & 2.
8vo.

Register zu den ersten X. Banden der Sitzungsberichte der Mathematisch-Natur-
wissenschaftlichen Classe. 8vo.

Conducted by Professors Silliman and

Jahrbiicher der K. K. Central-Anstalt fiir Meteorologie und Erdmagnetismus. Von
Karl Kreil. Herausgegeben durch die Kaiserliche Akademie der Wissen-
schaften). 2 Bd. 4to.

Annalen der Koniglichen Sternwarte bei Miinchen. VI. Bd. 8vo.

Magnetische Ortsbestimmungen an verschiedenen Puncten des Konigreichs Bayern
und an einigen auswartigen Stationen. I. Theil. 8vo.

Magnetische Karten von Deutschland und Bayern. Von Dr J. Lamont. Fol.

Transactions of the Linnean Society of London. Vol. xxi., Parts 2 and 3. 4to.

December 3, 1855.

Transactions of the Royal Scottish Society of Arts, Vol iv., Part 3. 8vo.

The Journal of Agriculture, and Transactions of the Highland and Agricultural
Society of Scotland. N.S. Nos. 49,50. 8vo.

Transactions of the Architectural Institute of Scotland. Session 1854—5.

Proceedings of the Royal Society. Vol. vii., No. 14. 80.

Results of Astronomical Observations, made at the Observatory of the University,
Durham, from October 1849 to April 1852, under the general direction of
the Rev. Temple Chevallier, B.D., F.R.A.S. By R. C. Carrington, Esq., B.A.,
F.R.A.S. 8vo.

The Assurance Magazine, and Journal of the Institute of Actuaries.

8vo.

Vol. v., Part

4; Vol. v., Part 1. 8vo.
Journal of the Statistical Society of London. Vol, xviii., Parts 1, 2, 3. 8vo.
The Quarterly Journal of the Geological Society. Vol. ii., Parts 1, 2, 3. 8vo.

The Journal of the Horticultural Society of London.

Monthly Notices of the Royal Astronomical Society, Vol. xiv. 8vo.

The Journal of the Royal Geographical Society. Vol. xxiv. 8vo.

The Journal of the Royal Asiatic Society of Great Britain and Ireland. Vol. xv.,
Part 2. 8vo.

Journal of the Geological Society of Dublin. Vol. vi., Part 2. 8vo.

The Quarterly Journal of the Chemical Society. Vol. viii, Part 2. 8vo.

Notices of the Meetings of the Members of the Royal Institution of Great Britain.
Part 5.

Proceedings of the Liverpool Literary and Philosophical Society.
8vo.

Journal of the Asiatic Society of Bengal. Nos. 70,71, 72. 8vo.

Abstracts of the Proceedings of the Ashmolean Society. Vols. i., ii., iii., Part 1.

Vol. ix., Part 4. 8vo.

Session 1854-5.

8vo.
Memoirs of the Literary and Philosophical Society of Manchester. 2d Series, Vol.
Xi, xii. 8vo,

Vhe American Journal of Science and Arts.

Conducted by Professors Silliman
and Dana. Nos. 57, 58, 59. 8vo.

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Collection of Charts published at the Hydrographic Office, London.

Astronomical Observations, made at the Radcliffe Observatory.
Johnstone, M.A., 1850, 1851, 1852. 8vo.

Archeologia, or Miscellaneous Tracts relating to Antiquity, published by the Society
of Antiquaries of London. Vol, xxxi. 4to.

Proceedings of the Society of Antiquaries of London. Vol. iii, No. 52, 8vo.

Descriptive and Illustrated Catalogue of the Histological Series contained in the
Museum of the Royal College of Surgeons of England. Vol. ii. 4to.

Assault of Sevastopol. Two Topographical and Panoramic Sketches, represent-
ing the advanced lines of attack, and the Russian defences, in front of Se-
vastopol, with a description and remarks. The sketches by Capt. M. A. Bid-
dulph, R.A.

Transactions of the Zoological Society of London. Vol. iv., Parts 2, 3. 4to,

The Origin and Progress of the Mechanical Inventions of James Watt, illustrated
by his correspondence with his friends, and specification of his patents. By
James Patrick Muirhead, Esq., M.A., 3 vols. 4to.

Researches on Colour Blindness. By George Wilson, M.D. 8vo.

Magnetical and Meteorological Observations made at the Hon. East India Com-
pany’s Observatory, Bombay, in the year 1851. to.

Astronomical and Magnetical, and Meteorological Observations made at the Royal
Observatory, Greenwich, in the year 1853. 4to.

Memoirs of the Royal Astronomical Society. Vol. xxiii. to,

Abstracts from the Meteorological Observations taken at the Stations of the Royal
Engineers in the year 1853-4. Edited by Lieut. Col. H. James, R.E. 4to.

Papers read at the Royal Institute of British Architects. Session 1854-5, to.

Memoir of Robert Troup Paine. By his Parents. 4to.

Materia Medica and Therapeutics. By Martyn Paine, M.D.

The Institutes of Medicine. By Martyn Paine, M.D. 8vo.

Medical and Physiological Commentaries. By Martyn Paine,M.D. 3 Vols.

A Discourse on the Soul and Instinct. By Martyn Paine, M.D. 18mo.

Reports and State Documents published by the Senate of Washington.

Documents relating to the Colonial History of the State of New York. Vols. iii.
andiv. 4to.

Smithsonian Report.
Catalogue. 8vo.

Smithsonian Contributions to Knowledge. Vol. vii. Ato.

Eighth Annual Report of the Board of Regents of the Smithsonian Institu-.
tion.

Bulletins de l’Académie Royale des Sciences, des Lettres, et des Beaux Arts de Bel-
gique. Tome xxi., 2™° Partie. Tome xxii., 1" Partie. 8vo.
Essai d’une Géographie Physique de la Belgique. Par J, C. Houzean. 8vo.
Mémoires Couronnés et mémoires des savants étrangers, publiées par |’Académie
Royale de Belgique. Tome vi., 2™° Partie. 8vo.
Annalen der Koniglichen Sternwarte bei Miinchen. 7 Band.
Jahresbericht der Miinchener Sternwarte fiir. 1854. 8vo.
Monatsbericht der Konig]. Preus, Akademie der Wissenschaften zu Berlin, August,
December. 1854. 8vo,

Abhandlungen der Mathematisch-physikalischen Classe der Koeniglich Bayerischen
Akademie der Wissenschaften. 7 Bd., 2 Abtheil. to.

Abhandlungen der Historischen Classe der Koeniglich Bayerischen Akademie der
Wissenschaften. 6 Bd., 2 Abtheil. 4to.

Preisschriften gekront und herausgegeben von der Fiirstlich Jablonowskischen
Gesellschaft zu Leipzig. No. 5. 8vo.

Nova Acta Academiz Czesareze Leopoldino-Carolinze Nature Curiosorum. Vol. xxiv.,
Pars 2. » 4to.

Denkschriften der Kaiserlichen Akademie der Wissenschaften.
Naturwissenschaftliche Classe. Bd. viii.

8vo.
By Manuel J.

12mo.

8vo.

On the Construction of Catalogues of Libraries, and a General

8vo.

Mathematisch-

687

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The Society.

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Capt. Young-
husband.

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The Authors.
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York.
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The Academy.

The Academy.
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The Academy,

688 LIST OF DONATIONS.
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DONATIONS.

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch-
Naturwissenschaftliche Classe. Bd. xiv, und Bd. xv., Heft. lund 2. 8vo.

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Philosophische
Historische Classe. Bd. xiv. and Bd. xv., Heft. 1. 8vo.

Almanach der Kaiserlichen Akademie der Wissenschaften. 1855. 12mo.

December 17, 1855.

Jahresbericht tiber die Fortschritte der reinen, pharmaceutischen und technischen
Chemie, &c. Herausg. von Liebig und Kopp. 1854. 8vo.

Die Fortschritte der Physik in den Jahren, 1850, 1851,1852. Dargestellt von der
Physikalischen Gessellschaft zu Berlin. 8vo.

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Bd. xv., Heft, 2
und 8; Bd. xvi., Heft. 1. Philosophisch-Historische Classe. 8yo.

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften, Mathematisch-
Naturwissenschaftliche Classe. Bd. xv., Heft. 3; Bd. xvi., Heft. 1. 8vo.

Abhandlungen der Philosoph.-Philologischen Classe der Koeniglich Bayerischen
Akademie der Wissenschaften. Bd. xvii., 2 Abtheil. 4to.

Denkrede auf die Akademikir Dr Thaddius Liber und Dr Georg Simon Ohm, von
Dr Lamont. 4to.

Almanach der Kéniglich Bayerischen Akademie der Wissenschaften, fiir das Jahr
1855. 12mo.

Archives du Muséum d’Histoire Naturelle, publiées par les professeurs-administra-
teurs de cet établissement. Tome vii., Liv. 3 et 4; Tome viii, Liv. 1
et 2. Ato.

Aanteekeningen van het verhandelete in de Sectie Vergaderingen van het Provinciaal
Utretsch Genootschop van Kunsten en Wetenschappen. 1845-54. 8vo.
Verhandeling over de verdiensten van Gijsberet Karel van Hogendorp, als Staut-

shuishoudkundige ten aanzien van Nederlands, door M, O. Van Rees. 8vo.

Description de l’Observatoire météorologique et magnétique 4 Utrecht. Par P. W.
C, Krecke. 8vo.

Astronomical and Meteorological Observations made at the Radcliffe Observatory in
the year 1853, under the superintendence of Manuel J. Johnson, M.A. Vol.
xiv. 8vo.

Memorie della Accademia delle Scienze dell’ Istituto di Bologna. Tomov. 4to.

Journal of the Asiatic Society of Bengal. Nos. 3 and 4, 1855. 8vo.,

Almanaque Nautico para el aio 1856, calculado de orden de J. M. en el Observatoro
de Marina de la Ciudad de San Fernando, 8vo.

Jahrbuch der Kaiserlich-K6niglichen Geologischen Reichsanstalt. 1854. Nos, 2,
3,&4. 8vo.

Bulletin de la Société de Géographie. 4'°™° Serie. Tom. 8&9. 8vo,

Berichte iiber die Verhandlungen der Koniglich Sichsischen Gesellschaft der
Wissenschaften zu Leipzig. 1854-5. 8vo.

Bulletin de la Société Impériale des Naturalistes de Moscou. 1658. Nos. 3 & 4.
1854. No.1. 8vo.

Medico-Chirurgical Transactions. Published by the Royal Medical and Chirurgical
Society of London. Second Series. Vol. xx. 8vo.

Journal of the Ethnological Society of London. Vols. i, ii, ili, 8vo.

Transactions of the Pathological Society of London, Vol. vi. 8vo.

Journal of the Statistical Society of London. Vol. xviii. Part 4. 8vo.

Observations Météorologiques faites 4 Nijné Tagulsk (Monts Oural). Governement
de Perm. 1850-51-52-53. 8vo.

Collection of Naval Charts from the Depét General dela Marine. 8vo.

Verhandelingen der Koninklijke Akademie van Wetenschappen. 2% Deel. to.

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Ditto.

The Trustees.

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The Society.

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» The Society.

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Ditto.

Ditto.
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Government.
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LIST OF DONATIONS.

DONATIONS.
Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen.
Deel. 3° Stuk., 3% Deel. 15*€ and 2% Stuk. 8vo.
Catalogus der Boekeri van de Koninklijke Akademie van Wetenschappen, gevestigd
te Amsterdam, 1%¢ Afler. 8vo.
Analytisch-geometrische Untersuchungen iiber Allgemeine Verwandtschafts-Ver-

Ode

hiltnisse von Coordinaten-Systemen. Von J. G. H. Swellengebel. 4to.
Kongl. Vetenskaps Akademiens Handlingar. 1853. 8vo.
Kongl. Vetenskaps Akademiens Ofversigt. 1854, 8vo.
Kong], Vetenskaps Akademiens Arsberattelser af Wikstrém, 8vo.
Kongl. Vetenskaps Akademiens Arsberattelser af Boheman. 8vo.,
Memorie della Reale Accademia delle Scienze di Torino. Tome xiv. 4to.

Mémoires de l’Académie Royale des Sciences, des Lettres et des Beaux Arts de
Belgique. Tomes xxviii, xxix. 4to,

Denkschriften der Kaiserlichen Akademie der Wissenschaften.
Naturwissenschaftliche Classe. B’9. 4to.

Denkschriften der Kaiserlichen Akademie der Wissenschaften.
torische Classe. B’6. 4to.

Jahrbiichr der K. K. Central-Anstalt fiir Meteorologie und Erdmagnetismus. Von
Karl Kreil. III. Bd. 1851. 4to.

Bulletin der Konig]. Akademie der Wissenschaften (Miinchen). Nos. 1-52. 4to.,

Compte Rendu Annuel, par le Directeur de l’Observatoire Physique Central, A. T.
Kiipffer. 1853. 4to.

Della vita e delle opere di Guido Bonatti, Astrologo ed Astronomo del secolo decimo-
terzo notizie raccolte da B. Boncompagni. 8vo.

Annuaire de )’Académie Royale des Sciences, &c. de Belgique. 1854-55,

Académie Royale de Belgique, Bibliographie Académique. 1854. 12mo.

Annuaire de l’Observatoire Royal de Bruxelles. 1854-55. 12mo.

Almanach Seculaire de l’Observatoire R. de Bruxelles. 1854. 12mo.

Mathematisch-

Philosophisch-His-

12mo.

March 17, 1856.

Exhibition of the Works of Industry of all Nations, 1851. Reports by the Juries
on the Subjects in the Thirty Classes into which the Exhibition was divided,
4 vols. fol.

Journal of the Proceedings of the Linnzean Society. Vol. i.,No. 1. 8vo.
American Journal of Science and Arts. Vol. xxi., No. 61. 8vo.
Journal of the Statistical Society of London, Vol. xix., Part 1. 8vo.

Quarterly Journal of the Geological Society. Vol. xii, Part 1. 8vo.

Die Fortschritte der Physik im Jahre 1852. Dargestellt von der Physikalischen
Gesellschaft zu Berlin. 2° Abtheil. 8vo,

Annalen der Koniglichen Sternwarte bei Miinchen. B48, 8vo,

Tables showing the Number of Criminal Offenders in England and Wales, in the
year 1854. Fol.

A Collection of Charts published at the Hydrographic Office, London.

April 7, 1856.
Assurance Magazine, and Journal of the Institute of Actuaries. Vol. vi., Part 3. 8vo.

Proceedings of the Ashmolean Society, 1855. 8vo.
The Journal of Agriculture, and the Transactions of the Highland and Agricultural

Society of Scotland. N.S8., No. 52. 8vo.,
Journal of the Asiatic Society of Bengal. N. S., Nos. 5 & 6, 1855. 8vo.
Bulletin de la Société de Géographie. 4™° Série. Tome x. 8vo.

Verhandlungen der Kaiserlichen Leopoldinisch-Carolinischen Akademie der Natur-
forscher. B‘, xxiv., Supp. B¢. xxv., Heft 1. to.
VOL. XXI. PART IV.

689

DONORS.
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Ditio.

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Ditto.

Ditto.
The Editor.

The Author.

The Academy.
Ditto.
Ditto.
Ditto.

H. F. Talbot,
Esq.

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The Editors.

The Society.
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Ditto.

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H.M. Admiralty.

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Ditto.
Ditto.
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8 Y

690 LIST OF DONATIONS.

DONATIONS.

Smithsonian Contributions to Knowledge. Vol. vii. to.

Abhandlungen der Kaiserlich-Koniglichen Geologischen Reichsanstalt.
1855. Fol.

Jahrbuch der Kaiserlich-Kéniglichen Geologischen Reichsanstalt, 1855. 8vo. No. 1.

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch-
Naturwissenschaftliche Classe, B®, xvii., Heft 3. 8vo.

Coup d’wil Géologique sur les Mines de la Monarchie Autrichienne.
Hauer & Fr. de Feetterle. 8vo.

Band 2,

Par Fr. de

April 21, 1856.

Report of the Yellow Fever Epidemic of British Guiana, By Daniel Blair,M.D. 8vo.

Physical and Geographical Map of India. By G. B. Greenough, 8vo.

Théorie de l’Antagonisme et de la Pondération, Par M. Alexandre Gérard,

London University Calendar, 1856. 12mo,

Proceedings of the Botanical Society of Edinburgh, 1855. 8vo.

The Quarterly Journal of the Geological Society. Vol. ii., Part 4.

Flora Batava, Afleverings 177 & 178. Ato.

Abhandlungen, herausgegeben von der Senckenbergischen Naturforschenden Gesell-
schaft. 1%t Band, 2°, Lieferung. 4to.

Memorias de la Real Academia de Ciencias de Madrid, Tome1l & 2. 8yo.,

Positions moyennes pour l’époque de 1790,0 des étoiles cireompolaires, dont les ob-
servations ont été publiées par Jérome Lalande dans les Mémoires de l’ Aca-
démie de Paris de 1789 et 1790. Par Ivan Frederenko, 4to,

Ueber Dr Wichmann’s Bestimmung der Parallaxe des Argelanderschen Sterns, Von
W. Dillen, 4to.

Comptes Rendus hebdomadaires des Séances de l’Académie des Sciences.
1855—Avril 1856. 4to.

8yvo.

8yo. -

Noy.

December 1, 1856.

Collection of Charts, published at the Hydrographic Office, London, with relative
Descriptions,

Results of Meteorological Observations, made at Sundry Academies in the State
of New York, from 1826 to 1850 inclusive. Compiled by F. B. Hough,
M.D. 4to.

Annual Report of the Trustees of the New York State Library, 1856. 8vo.

List of Members and Report of Council, &c., of the Royal Institute of British
Architects, 1856. 4to.

Map of Boundary between the United States and Mexico.
U.S. Commissioner.

Smithsonian Contributions.to Knowledge. Vol. viii. 4to.

List of Foreign Correspondents of the Smithsonian Institution, 1856. 8vo.

Nova Acta Academie Casarez Leopoldino-Caroline Nature Curiosorum. Vol.
xxv., Pars2. 4to.

Mean Zenith Distances, Collection of all the Results of Observations of each
star at Heerelogements-Berg, and Deduction of Mean Zenith Distance, 1843.
January 0.

Memoirs of the Royal Astronomical Society. Vol. xxiv. 4to.

Astronomical, Magnetical, and Meteorological Observations made at the Royal
Observatory, Greenwich, in the year 1854. 4to.

Magnetical and Meteorological Observations made at the Hon. East India Com-
pany’s Observatory, Bombay, in the years 1852-53. 2 vols. 4to.

Memoirs of the American Academy of Arts and Sciences. New Series.
Part 2.

By W. H. Emory,

Vol, v.,

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King of Holland,
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The Academy.
The Editor.

The Author.

The Academy.

The Admiralty.

The State of
New York.

Ditto.
The Institute.

Smithsonian
Institution.
Ditto.
Ditto.
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The Observatory,
Cape of Good
Hope.

The Society.
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ciety.

The Hon. E. I.
Company.
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LIST OF DONATIONS.

DONATIONS.

Proceedings of the American Association for the Advancement of Science. Ses-
sions 1853, 1854, and 1855.

Proceedings of the Academy of Natural Sciences of Philadelphia. Vol. vii.,

Nos. 8-12; and Vol. viii., Nos. 1 and 2.

Annales de l’Observatoire Physique Central de Russie. Ann. 1851, 1852, 1852,
3 Tom. 4to.

Comte-Rendu Annuel, Supplement aux Annales de l’Observatoire Physique
Central, pour l’année 1853. (2 copies.)

Correspondance Météorologique. Publication trimestrielle de 1’ Administration
des Mines de Russie, pour ann. 1853, 1854. 2 Tom. 4to.

Denkschriften der Kaiserlichen Akademie der Wissenschaften, Mathematisch-
Naturwissenschaftliche Classe. Bande x., xi. 4to. (2 copies.)

Beschreibung und Lage der Universitats-Sternwarte in Christiania, von Christo-
pher Hansteen. 4to.

Ofversigt af Finska Ventenskaps-Societetens Forhandlingar, 1838-53. 4to.

Observations faites 4 l’Observatoire Magnétique et Météorologique de Helsing-
fors, sous la direction de Jean Jacques Nervander. Vol.i., 11, il, et
iv. 4to.

Verhandelingen der Koninklijke Akademie van Wetenschappen. Deel. ii. 4to.

Oversigt over det danske Videnskabernes Selskabs Forhandlinger i Aaret, 1855.

Videnskabernes Selskabs Skrifter. 5te Rakke. Naturvidenskabelig og Mathe-
matisk Afdeling. 4de Bande, Iste Hefte.

Observations Metereologice per annos 1832-54 in Gronland factz.

Flora Batava. Part 179, 4to.

Memoire della Accademia della Scienze dell’ Istituto di Bologna. Tom. vi.
4to.

Rendiconto delle Sessioni 1854-55, dell’ Accademia delle Scienze dell’ Istituto
di Bologna. 8vo.

Indices Generales in Novos Commentarios Academia Scientiarum instituti
Bononiensis. 4to.

Mémoires de la Société de Physique et d’Histoire Naturelle de Genéve. Tom. xiv.
Part 1. 4to.

Rapport sur les Travaux de la Société Impériale Zoologique, Paris. Par Aug.
Duméril. 8vo.

Ichthyologie Analytique ou Essai d’une Classification Naturelle des Poissons.
Par A. M. C. Duméril. 4to.

Abhandlungen der Koeniglich Bayerischen Akademie der Wissenschaften. Histo-
rischen Classe, Vol. vii., Part 3; Vol. viii., Part 1. Philosoph.-Philologis-
chen Classe, Vol. vii., Part 3. 4to.

Gelehrte Anzeigen, herausgegeben von Mitgliedern der K. bayer Akademie der
Wissenschaften. Vols. xl. xli. 4to.

Archives du Muséum @Histoire Naturelle. Tome viii., livraisons 3,4. 4to.

Monatsbericht der Koniglichen Preuss, Akademie der Wissenschaften zu Berlin,
January—June 1855. 8vo.

Observations Météorologiques faites a Nijne-Taguilsk (Monts Oural), Gouverne-
ment de Perm. Année 1854. 8vo.

Bulletin de la Société Vaudoise des Sciences Naturelles. Nos, 34, 37.

Jahrbuch der Kaiserlich-Koniglichen Geologischen Reichsanstalt.

Nos. 2,4; Vol. viu., No.1. 8vo.

Abhandlungen der Kaiserlich-Kéniglichen Geologischen Reichsanstalt.
ii, 4to.

Memoire della Reale Accademia delle Scienze di Torino. 2d Ser. Vol. xv. 4to.

Jahrbiicher der K. K. Central-Anstalt fiir Meteorologie und Erdmagnetismus,
Von Karl Kreil. Vol. iv. 4to, (2 copies.)

Abhandlungen der Akademie der Wissenschaften zu Berlin, 1854.

Portrait of Karl Haidinger.

Journal of the Royal Asiatic Society of Great Britain and Ireland. Vol. xvi.,
Part 2. 8vo.

8vo.
Vol. vi.,

Vol.

4to.

691

DONORS,
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The Academy.
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The Observatory.

The Society.

The Observatory.

The Academy.
The Society.
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Ditto. ;
King of Holland.
The Academy.

Ditto.

Ditto.
The Society.
The Author.

Ditto,

The Academy.

Ditto.

The Museum,
The Academy.

The Russian
Observatory.

The Society.

The Institute.

Ditto.

The Academy.
Academy of
Sciences, Vienna.
The Academy.
From his Son.
The Society.

692 LIST OF DONATIONS.

DONATIONS,

Publications of the Dépét Général de la Marine :—

Collection of Charts.

Pilote de la Mer Baltique. 8vo.

Portulan des Cotes de la Manche.

Le Pilote Danois. 8vo.

Renseignements Hydrographiques sur la Mer d’Azof. 8vo.

Description du Golfe de Finlande et de lentréedu Golfe de Bothnie, 8vo.

Observations Chronometriques faites pendant la Campagne de Circum-
navigation de la Corvette Capricieuse, 8vo.

Manuel de la Navigation dans la Mer Adriatique. 8vo.

Exposé du Régimie des Courants Observés dans la Manche et la Mer
d’Allemagne. 8vo.

Description des Cotes de 1’Esthonie, de la Livonie, de la Courland
(Russie), de la Prusse, et de la Pomeraine, jusqu’au Cap Darse-
rort. 8vo,

Routier de l’Australie Traduit de l’Anglais, &c. 8vo.

Annales Hydrographiques, Recueil d’Avis, Instructions, Documents, et
Mémoires relatifs a Hydrographie et a la Navigation. 8vo.

Catalogue Chronologique des Cartes, Plans, Veus de Cétes, Mémoires,
Instructions Natiques, &c,, qui composent l’Hydrographie Fran-
¢aise. 8vo.

Annuaire des Marées des Cotes de France, pour l’an 1855, 16mo.

Vierzehn Kupfertafeln zu H. B. Geinitz Darstellung der Flora des Hainichen—
Ebersdorfer und des Fléhaer Kohlenbassins,

Descriptive and Illustrated Catalogue of the Histological Series contained in the
Museum of the Royal College of Surgeons of England. Vol. i., Elementary
Tissues of Vegetables and Animals, 4to.

A Monograph on Recent and Fossil Crinoidee, with Figures and Descriptions of
some Recent and Fossil allied Genera. By Thomas Austin, F.G.S. Nos. 1-
8. Ato.

Medico-Chirurgical Transactions, published by the Royal Medical and Chirur-
gical Society of London. Vol, xxxix. 8vo.

Report of the U.S. Commissioner of Patents for the year 1854. Agriculture,
Arts, and Manufactures. Vol. ii. 8vo.

Memoirs of the Literary and Philisophical Society of Manchester. Second Series,
Vol, xiii. 8vo, .

Proceedings of the Zoological Society of London. Part xx., Nos. 258, 259;
Parts xxi., xxii., and Part xxii., Nos. 301-313. 8vo,

The Assurance Magazine and Journal of the Institute of Actuaries, Nos. 25,
and 26. 8vo.

Proceedings of the American Philosophical Society, 1855, Nos, 53 and 54, 8vo.

Proceedings of the Boston Society of Natural History, May—December 1855,
and January—April 1856, 8vo.

Annals of the Minnesota Historical Society, 1856; containing Materials for the
History of Minnesota, prepared by E. D. Neill, Secretary. 8vo.

Journal of the Royal Dublin Society. No.1. 8vo,

Transactions of the Pathological Society of London, Vol. vii. 8vo.

Journal of the Asiatic Society of Bengal. Nos. 77-81 (New Series). 8vo.

Astronomical and Meteorological Observations made at the Radcliffe Obser-
vatory, Oxford, in the year 1854. Vol. xv. 8vo.

8vo.

Medical Topography of Brazil and Uruguay, with Incidental Remarks. By
G. R. B. Horner, M.D. 8vo.
Description of a New Mollusk, from the Red Sandstone near Pottsville, Pa. By

Isaac Lea.

Meteorology and Climate of Shanghae ; deduced from Observations made during the
years 1848-53. By John Ivor Murray, M.D., F.R.C.S.E.

The Canadian Journal of Industry, Science, and Art. New Series, Nos. 3 and 5,
8vo.

DONORS.
Dépot-Général de
la Marine, Paris.

The Author.

, The Council of
the College.

The Author,

The Society.
The Commis-
sioner.
The Society.
Ditto.
The Editor.

The Society.
Ditto.

Ditto.
Ditto.
Ditto.
Ditto.
Radcliffe Trustees.
The Author.
Ditto.
Ditto.

The Canadian
Institute.

LIST OF DONATIONS.

DONATIONS.

- Om Dodeligheden i Norge. Af Gilert Sundt. 12mo.

The Natural History of Deeside and Braemar. By the late William Macgillivray,
LL.D. Edited by Edwin Lankester, M.D. 8vo.

The American Journal of Science and Arts. Conducted by Professors Silliman and
Dana. Second Series. Nos. 62-64. 8vo,

Proceedings of the Academy of Natural Sciences of Philadelphia.
7-12; Vol. viii., No. 1. 8vo.

Report on the Geology of Northern and Southern California.
Trask. 8vo.

The Journal of Agriculture, and Transactions of the Highland and Agricultural
Society of Scotland. New Series, Nos. 50-53. 8vo.

Journal of the Statistical Society of London. Vol. ix., Parts 2and 3. 8vo.

The Quarterly Journal of the Geological Society. Vol. xii., Parts 2,3,and 4, 8vo.

Vol. vi., Nos.
By Dr John B.

Transactions of the Historic Society of Lancashire and Cheshire. Vol. viii. 8vo.
Laws of the Historic Society of Lancashire and Cheshire.
Journal of the Geological Society of Dublin. Vol. vii., Parts 1,2, and 8. 8vo.

Proceedings of the Royal Geographical Society of London. Nos, 1, 2,3,4,and5. 8vo.

Journal of the Royal Geographical Society. Vol. xxv. 8vo.

An Account of the Construction of the Britannia and Conway Tubular Bridges. By
William Fairbairn, C.E. 8vo.

On the Application of Cast and Wrought Iron to Building Purposes.
Fairbairn, C.E. 8vo.

Useful Information for Engineers; being a Series of Lectures delivered to the
Working Engineers of Yorkshire and Lancashire. By William Fairbairn,
F.R.S. 8vo.

Journal of the Ethnological Society of London. Vol. iv.

Regulations of the Ethnological Society of London. 8vo.

A Treatise on Electricity in Theory and Practice. By Aug. de la Rive.
lated for the Author by Charles V. Walker, F.R.S. Vol. ii. 8vo.

Report of the Proceedings of the Geological and Polytechnic Society of the West
Riding of Yorkshire, 1855. 8vo.

The Twenty-Third Annual Report of the Royal Cornwall Polytechnic Society, 1855,

By William

8vo.

Trans-

8y0.
Notices of the Meetings of the Members of the Royal Institution of Great Britain.
Part 6. 8vo.

Proceedings of the Yorkshire Philosophical Society. Vol. 1. 8vo.

Proceedings of the Literary and Philosophical Society of Liverpool during the Forty-
fifth Session, 1855-56. No. x.

Monthly Notices of the Royal Astronomical Society, containing Papers, Abstracts of
Papers, and Reports of Proceedings of the Society. Vols, xv. and xvi., Nos.
6-9. 8vo.

The Quarterly Journal of the Chemical Society. Nos. 33-35.

Proceedings of the Royal Society. Vol. viii., Nos. 21, 22. 8vo.

List of Fellows of the Royal Astronomical Society, February 1856. 8vo.

On the Tree Producing Red Cinchona Bark. By John Eliot Howard, 8vo.

Papers read at the Royal Institute of British Architects, 1856. 4to.

Journal of the Proceedings of the Linnean Society. Vol. i., Nos. 2 and 3. 8vo,

Narrative of the Origin and Formation of the International Association for ob-

8vo.

taining a uniform Decimal System of Measures, Weights, and Coins. By
James Yates, M.A. 8vo.
_ Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften, Wien. Philo-

sophisch-Historische Classe, Band xvi., Heft 2; xvii., xviii, xix.; xx.
Heft 1. Mathematish-Naturwissenschaftliche Classe, Band xvi., Heft 2;
XVli., XVili., xix., and xx,, Heft 1. 8vo.
Almanach der Kaiserlichen Akademie der Wissenschaften, Jahr. 1856.
Jahresbericht iiber die Fortschritte der reinen, pharmaceutishen und technischen
Chemie, Physik, Mineralogie, und Geologie, Herausgegeben von Justus
Liebig und Hermann Kopp. Fiir 1855. 8vo.
VOL. XXI. PART IV.

693

DONORS.
The Author.
From H.R.H.
Prince Albert.
The Editors,

The Academy.

The State of
California,
The Society.

Ditto.
Ditto.
Ditto.
Ditto.
Ditto.
Ditto.
Ditto.
The Author.

Ditto.
Ditto.

The Society.
Ditto.

The Author,

The Society.
Ditto.

The Institution,

The Society.
Ditto.

Ditto.

Ditto.
Ditto.
Ditto.
The Author.
The Society.
Ditto.
The Author.

The Academy.

Ditto,
The Editors.

8 Z

694 LIST OF DONATIONS.

DONATIONS.

Abhandlungen der Koniglichen Gesellschaft der Wissenschaften zu Gottingen.
Band. vi. 4to.

Verslagen en Mededeelingen der Koninklijke Akademie van Wetenschappen,
Amsterdam, Afdeeling Natuurkunde, Deel iii., No. 3; iv. Nos. 1-3.
Afdeeling Letterkunde, Deel i. ii., No. 1.

Berichte iiber die Verhandlungen der Koniglich Sichsischen Gesellschaft der
Wissenschaften zu Leipzig. Philologisch-Historische Classe, 1855, Nos. 3,
4; 1856, Nos.1,2. Mathematisch-Physische Classe, 1854, No. 3; 1855,
Nos. 1,2; 1856, No.1. 8vo.

Nachtrag zu Stadtrechte der Latinischen-Gemeinden Salpensa und Malaca in der
Provinz Betica. Von Theodor Mommsen. 8vo.

Nachtragezur Theorie der Musikalischen Tonverhiltnisse. VonM.W. Drobisch, 8vo.

Elecktrodynamische Maassbestimmungen insbesondere zuriickfiihrung der Stro-
mintensitits-Messungen auf Mechanisches Maas. Von R. Kohlrausch und
Wilhelm Weber, 8vo.

Resulate aus Beobachtungen der Nebelfleeken und Sternhaufen. Von H. D’Ar-
rest. 8vo.

Berechnung der Absoluten Stérungen der Kleinen Planeten. Von P. A. Han-
sen. 8vo.

Extrait du Programme de la Société Hollandaise des Sciences 4 Haarlem, pour
Vannée 1856. 4to.

Natuurkundige Verhandelingen van de Hollandsche Maatschappij der Weten-
schappen te Haarlem. 2 Verzameling. Deel xi., Stuk. 2. 4to.

Forhandlingar vid de Skandinaviske Naturforskarnes sjette mote i Stockholm,
den 14-19 Juli, 1851. 8vo.

Kongl. Vetenskaps-Akademiens Handlingar, for ar. 1853, 1854. 8vo.

Ars-Beraittelse om Botaniska Arbeten och upptiacker for ar. 1851.
Em. Wilkstrém. 8vo.

Ofversigt af Kongl. Vetenskaps-Akademiens Forhandlingar.

Af Joh.

Tolfte argangen,

1855. 8vo.
Ofversigt af Finska Vetenskaps, Societetens Forhandlingar.—ii. ili. (1853-56.)
Ato.

Acta Societatis Socientiarum Fennice. Tom. iv. and v., Fase. 1.

Recherches Experimentales sur la Végétation. Par Georges Ville.

Medimalcollegiets Skjebne. 8vo.

Syphilisationen Studeret ved Syngesengen, af Wilhelm Boeck. 8vo.

De Prisca re Monetaria Norvegiz et de Numis Aliquot et Ornamentis, in Nor-
vegia Repertis. Scripsit C. A. J. Holmboe. 8vo.

Kong Christian dens Fejerdes Norske Lovbog, af 1604. Af Fr. Hallager, og Fr.
Brandt, 8vo,

Om Mundtlig Rettergang og Edsvorne. Af C. Aubert. 8vo.

An Historical Summary of the Post-Office in Scotland, compiled from authentic
Records and Documents. By T. B. Lang. 8vo.

On the Swedish Tabulating Machine of Mr George Schentz.
F.R.S. 8vo.,

8vo.

By C. Babbage,

Annual Report of the Leeds Philosophical and Literary Society. 1855-6. 8vo.
Universitatis Regia Fredericianee Nove xdes Descripsit Ch. Holst, Sec. 8vo.
Histology of the Cholera Evacuations in Man and the Lower Animals. By W.

Lauder Lindsay, M.D. 8vo.

Almanique Nantico para 1857, Calculado de Orden de §.M., en el Observatorio
de Marina de la Ciudad de San Fernando.

Commercium Epistolicum J. Collins et aliorum de Analysi promota, &c., ou Cor-
respondance de J. Collins, et d’autres Savants célebres, du XVII. Siecle,
relative 4 l’analyse supérieure. Publiée par J. B. Biot et F. Lefort. 4to.

Det Kongelige Norske Frederiks Universitets Aarsberetning, 1853. 8vo.

Phenomena of the Material World. By D, Vaughan, 8vo.

On the Practicability of Constructing Cannon of Great Calibre, capable of en-
during long-continued use under full Charges. By Daniel Treadwell. 8vo.

DONORS,
The Society.

The Academy.

The Society.

Ditto.
Ditto.
Ditto.
Ditto.
Ditto.
Ditto.
Ditto.
Ditto.

The Academy.
Ditto.

Ditto.
The Society.

Ditto.
The Author.
The Editor,
The Author.

Ditto.

Ditto.

Ditto.
Ditto.

Ditto.

The Society.
The Author,
Ditto.

The Observatory.

Ministre d’In-
struction Pub-
lique.

The University.

The Author,

Ditto,

LIST OF DONATIONS..

DONATIONS.

On the Mechanical Properties of Metals as Derived from Repeated Meltings,
Exhibiting the Maximum point of Strength, and the Causes of Deterioration.
By W. Fairbairn, F.R.S. 8vo.

On Axes of Elasticity and Crystalline Forms. By W. J. M. Rankine, C.E. 4to.

Universal Writing and Printing with Ordinary Letters. By Alexander J. Ellis,
B.A. Ato.

Experimental Researches in Electricity. Thirtieth Series.
day, D.C.L. 4to.

On the Action of Non-Conducting Bodies in Electric induction.
D.C.L., and P. Riess. 8vo.

Expériences sur la Direction des Courants de l’Océan Atlantique Septentricnal.
Lettre de S. A. I. le Prince Napoléon 4 M. Elie de Beaumont, Secrétaire
perpétual de l’Académie des Sciences. 4to.

_ Lois Générales de divers ordres de Phénoménes dont l’analyse dépend d’Equa-
tions Linéaires aux Différences Partielles tels que ceux des Vibrations et de
la Propagation de la Chaleur. Par L. F. Ménabréa. 4to.

Bemerkninger Angaaende Graptolitherne af Christian Boeck. 4to.

Report of Committee upon the Experiments conducted at Stormontfield, near
Perth, for the Artificial Propagation of Salmon. Read before the British
Association by Sir William Jardine, Bart. 8vo,

Recherches Cliniques sur la Syphilisation. Par D, Wilhelm Boeck. 8vo.

Du Mouvement imprimé 4 ]’Aiguille Aimantée par l'influence subite de la Lu-
miére du Soleil, avec une Théorie nouvelle fondée sur des Recherches faites
par H. W. Jacobus. 8vo.

Schidel abnormer Form in Geometrischen Abbildungen, nebst Darstellung eimiger
Entwickelungs-Zustande Deckknochen, Von. J. Christ. Gustav. Luce,
M.D. Folio.

Reports of the Surveyor-General, Charles D. Bell, on the Copper Fields of Little
Namaqualand, and of Commander M. 8. Nolloth, of H.M.S. “Frolic,” on
the Bays and Harbours of that Coast. Folio.

Uber die durch Molekularbenegungen in starren leblosen Korpern bewirkten
Formveriinderungen. Von Joh. Friedr. Ludw. Hausmann. 4to.

Das Chemische Laboratorium der Universitat Christiania und die darin Ans-
gefiihrten Chemischen Untersuchungen. Herausgegehen von Adolph Strec-
ker. 4to.

Das Christiania-Silurbecken, Chemisch-Geognostisch Untersucht von Theodor
Kjerulf. Herausgegeben von Adolfph Strecker. 4to.

Akademiske Love for de Studerende ved det Kongelige Norske Frederiks Univer-
stet 8vo.

Uber den Syrisch-Ephraimitischen Kriez unter Jotham und Ahas,
P. Caspari.

Das Normalverhaltniss der Chemischen und Morphologischen Proportionen.
Adolf Zeising. 8vo,

Das Verhaltnisk des goldnen Schnitts in seiner Bedeutung fiir bildende Kiinstler und
Techniker. Von A. Zeising. 8vo.

Fagrskinna. Kortfattet Norsk Konge-Saga fra slutningen af det tolfte eller begyn-
delsen af det trettende aarhundrede. Af P.A. Munch og C.R. Unger. 8vo.

Om Sygepleien i Straffeanstalterne i Norge. Ved Frederik Holst, M.D. 8vo.

Michael Skjelderup. 8vo.

Beskrivelse over Skotlands Almueskoleveesen tilligemed forslag til forskjellige foram-
stalt-ninger til en videre Udvikling of det norske Almueskolevasen. Af
Hartvig Nissen. 8vo.

Beretning om fante-eller Landstrygerfolket i Norge. Af Cilert Sundt. 8vo.

Beretninger om Sygdomsforholdene i 1842 og 1843 i Danmark, Sverige og Norge,
opleste ved de Skandinaviske Naturforskeres Mode i Christiania 1844.
8vo.

Konge—Speilet et Philosophisk-Didactisk Skrift, forfattet i Norge mod Slutningen
af det tolfte aarhundrede, 8vo.

By Michael Fara-

By M. Faraday,

Von Dr C.

Von

695

DONORS.
The Author.

Ditto.

Ditto.

Ditto.
The Authors.

The Author.

Ditto.

Ditto.
Sir William Jar-
dine, Bart.

The Author.
Ditto.

Ditto.

The Governor,
Cape of Good
Hope.

The Author.

The University.

Ditto.

The University
of Christiania.
Ditto.

The Author.
Ditto.

The University
of Christiania.
The Author.
Ditto.
Ditto.

Ditto.
The University of

Christiania.

Ditto.

696 LIST OF DONATIONS.

DONATIONS.

Aslak Bolts Jordebog. Fortegnelse over Jordegods og Andre Herligheder tilhé-
rende erkebiskopsstolen i nidaros, affattet ved erkebiskop aslak bolts Foran-
staltning mellem aarene 1432 og 1449. Af P. A. Munch.

Kong Olaf Tryggvesins Saga forfattet paa latin henimod slutningen af det tolfte
aarhundrede af Odd Snorreson, Af P. A. Munch. 8yo.

Lycidas ecloga et Musze Invocatio, carmina quorum auctori Johanni van Leeuwen, e
vico zegwaart certaminis poetici premium secundum e legato Jacobi Henrici
Heoeufft adjudicatum est in concessu publico Academie Regiz Scientiarum, die
13 Maji, anni 1856. 8vo.

Diem Natalem Augustissimi Regis Caroli Joannis ab Universitate Regia Frederi-
ciana, die 26 Januarii 1838 celebrandum indicit Collegium Academicum, 4to.

Dr Lorenz Hiibner’s Biographische Charakteristik. Von Joseph Wiskmayr. 4to.

Ueber die Gliederung der Bevolkerung des K6nigreichs Bayern. Von Fr. B. W.
Von Hermann. 4to.

Maps of the Geological Survey of India,

December 15, 1856.

The Journal of the Canadian Institute. New Series. No.6. 8vo.
Silliman’s American Journal, No. 66. 8vo.
Journal of the Statistical Society of London. Vol. xix., Part 4. 8vo.

Schriften der Universitat zu Kiel, 1854, 1855. 4to.

Bulletin de la Société de Geographie. 4'°™¢ Serie, Tome xi.

Abhandlungen herausgegeben von der Senckenbergischen Naturforschenden Gesell-
schaft. Band ii, 1% lieferung. 4to.

January 5, 1857.

An Analysis of the Statistics of the Clearing House during the year 1839; with an
Appendix on the London and New York Clearing Houses, and on the London
Railway Clearing House. By Charles Babbage, F.R.S. 8vo,

Sanatory Remarks in Connection with Nuisances, By Thomas Williamson, M.D. 8yo.

January 19, 1857.

Publications of the Ailfric Society, viz. :—
1. The Homilies of A.lfric, with an English Translation.
F.S.A. 2 vols. 8vo. London, 1843-1846.
2. The Poetry of the Codex Vercellensis, with an English translation.
M. Kemble, M.A. 8vo. 1844-1856.
3. Anglo-Saxon Dialogues of Salomon and Saturn, By John M. Kemble, M.A.
8vo. 1845-1848.
Catalogue of the Law Books in the Library of the Society of Writers to Her Ma-
jesty’s Signet in Scotland. By William Ivory, W.S. 8vo, Edinburgh, 1856.
Jahresbericht iiber die Fortschritte der reinen, pharmaceutischen und technischen
Chemie, Physik, Mineralogie und Geologie. Herausgegeben von Justus Liebig
und Hermann Kopp, 1855, Zweites Heft. 8vo.
Memorias de la Real Academia- de Ciencias de Madrid, Tome iii,, iv.
Madrid, 1856.
Programa para la adjudicacion de premios en el ano 1857.
Anuncio del Eclipse anular y Central que tendra lugar el 15 de Marzo de 1858.
Por don Antonio Aguilar. 8vo.
‘Assurance Magazine, and Journal of the Institute of Actuaries, No, xxvi., January
1857.

By Benjamin Thorpe,
By J.

4to.

DONORS.
The University
of Christiania.

Ditto.

The Author,

The University.

The Author.
Ditto.

Hon. E I.
Company.

The Institute.

The Editors,

The Society.

The University.

The Society.
Ditto.

The Author.

Ditto,

Wn. Ivory, Esq.,
W.S.

The Author.

The Editors.

The Academy,

Ditto.
The Author.

The Institute.

LIST OF DONATIONS.

DONATIONS.
Pereement de |’Isthme de Suez. Rapport et Projet de la Commission Interna-
tionale. 8vo. Paris, 1856.

‘Flora Batava. 180 Aflevering. 4to.

y February 2, 1857,

Journal of the Asiatic Society of Bengal, No. v.

Catalogue of Stars near the Ecliptic, observed at Markree during the years
1854-56, and whose places are supposed to be hitherto unpublished. 8vo.
Vol. iv. (containing 14,951 stars).

Supplément aux Comptes Rendus Hebdomadaires de Seances de 1’Académie des

Sciences. Tom.i. 4to,
Mémoires de ]’Académie des Sciences de l'Institut Imperial de France. Tom.
xxvii. 1" partie. 4to.

Mémoires présentés par divers Savants 4 l’Académie des Sciences de 1’Institut
Imperial de France, et imprimis par son ordre. Sciences Mathematiques et
Physiques. Tom, xiv. 4to.

Proceedings of the Zoological Society. 8vo. Nos. 310-313.

Quarterly Journal of the Chemical Society, No. 36, January 1857. 8vo.

Nouveaux Mémoires de la Société Helvetique des Sciences Naturelles.
xiv. 4to.

Mittheilungen der naturforschenden Gesellschaft in Bern, fiir 1855, 1856.

Actes de la Société Helvetique des Sciences Naturelles, 1855. 8vo.

Verhandlungen der allgemeinen schweizerischen Gesellschaft fiir die gesammten
Naturwissenschaften bei ihrer versammlung in St Gallen am 24, 25, und
26 Juli 1851. &vo,

Comptes Rendus hebdomadaires des Séances de l’Académie des Sciences, May
1856—December 1856.

Band

8vo.

February 16, 1857.

Monograph of the genus Abrothallus, By W. Lauder Lindsay, M.D, 8vo,

Reports of the Meetings of the Royal Institute of British Architects,

Meteorological Observations taken during the years 1829 to 1852, at the Ordi-
nance Survey Office, Phoenix Park, Dublin; to which is added a series of
similar observations made at the principal trigonometrical stations, &c., in
Ireland, Edited by Captain Cameron R.E, (Lieut.-Col. H. James, R.E.,
Superintendent of Survey.)

Proceedings of the Royal Astronomical Society, xvii., No. 23. 8vo,

Memoires de la Société Impériale des Sciences Naturelles de Cherbourg. Vol.
ii, (1855). 8vo.

British Interests in the Canalization of the Isthmus of Suez. 8vo.

Papers read at the Royal Institute of British Architects, January 1857. 4to.

Tables showing the number of Criminal Offenders in England and Wales in the
year 1855, Folio,

Instructions for Making Meteorological Observations.

Monthly Returns of Births, Deaths, and Marriages registered in the Hight Prin-
cipal Towns of Scotland; with the causes of death at four periods of life.

Quarterly Returns of Births, Deaths, and Marriages registered in the Divisions,
Counties, and Districts of Scotland,

March 16, 1857.

First Report of the Committee on Beneficent Institutions (Medical Charities of
the Metropolis.)
VOL. XXI. PART IV.

697

DONORS.
The Suez Canal
Company.
King of Holland,

The Society.
H. M. Govern-
ment.

The Academy.
Ditto.

Ditto.

The Society.
Ditto.
Ditto.

Ditto.
Ditto.
Ditto.

Ditto,

The Author,

The Institute.

The Right Hon.
The Secretary
of State for
War.

The Society.
Ditto.

Canal Company.
The Institute.
Right Hon. Sec.
of State.
Scottish Meteoro-
logical Society.
The Registrar-
General.
Ditto,

Statistical Soe.
of London.

9A

698 © LIST OF DONATIONS.
DONATIONS.
Journal of the Statistical Society of London. Vol. xx., Part 1, 8vo.
The Canadian Journal (published by the Canadian Institute), January 1857.
Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften, Mathematisch-
Naturwissenschaftlichen Classe, Band xx., Heft 2 und 3; Band xxi,, Heft 1
und 2, Philosophisch-Historische Classe, Band xx., Heft 2 und 3; Band
xxi., Heft 1 und 2. Register zu den zweiten 10 Banden. 8vo.
Denkschriften der Kaiserlichen Akademie der Wissenschaften, Wien. Philo-
sophisch-Historische Classe, Siebenter Band. 4to,
Tageblatt der 32 versammlung Deutscher Naturforscher und Arzte in Wien im
Jahre 1856. Nos. 1-8. 4to.
Publications of the K6niglisch Sachsische Gesellschaft des Wissenschaften, Leipzig,
V1Z. <=
Beitrage zur Kenntniss der Gefasskryptogamen, von Wilhelm Hofmeister
8vo.
Die Urkundlichen quellen zur Geschichte der Universitat Leipzig in den
ersten 150 jahren ihres bestehens, von Friedrich Zarncke. 8vo.,
Elektrische Untersuchungen von W. G. Hankel, Erste Abhandlung,
Uber die Messung der Atmosphirischen Elektricitét nach absolutem
maasse. 68vo,
A General Index to the Philosophical Transactions, from the first to the end of
the seventeenth volume. By Paul Henry Maty,M.A.,F.R.S. 4to. Lon-
don, 1787.
Supplement to the Quarterly Returns of the Births, Deaths, and Marriages re-
gistered in the Divisions and Counties of Scotland. Year 1856.

April 6, 1857.

Monthly Return of the Births, Deaths, and Marriages registered in the eight prin-
cipal towns of Scotland, with the causes of Death at four periods of life, for
February 1857 ; and Supplement to Monthly Returns for year 1856. 8vo.

Journal of the Asiatic Society of Bengal. No. 7, 1856.

Proceedings of the Royal Astronomical Society. Vol. xvii., No. 4. 8vo.

Memoirs, icy of the Geological Survey of the United Kingdom, Wize

1B Figures and Descriptions Illustrative of British Organic Remains, 4to.
Decades 5 and 8.

2. The Iron Ores of Great Britain. Part I—The Iron Ores of the
North and North-Midland Counties of England. 8vo.

3. Mineral Statistics of the United Kingdom of Great Britain and Ire-
land, for 1853-55. By R. Hunt, F.R.S. 8vo.

4. Geology of the Country around Cheltenham. By Edward Hull, A.B.
8yo0.

5. On the Tertiary Fluvio-Marine Formation of the Isle of Wight.
Edward Forbes, F.R.S. 8vo.

6. Prospectus of the Metropolitan School of Science applied to Mining and
the Arts. 6th Session, 1856-57.

7. Collection of Maps and Sections.

8. Annual Report of the Director-General of the Geological Survey.

‘Almananee Nautico para 1858, calculado de Orden de S. M. en el observatorio de
Marina de la Ciudad de au Fernando. 8vo.

Assurance Magazine, and Journal of the Institute of Actuaries, April 1857. 8vo.

Memoir on the Roman Garrison at Mancunium; and its probable influence on the
Population and Language of South Lancashire. By James Black, M.D.,
F.G.8. 8vo.

Monatsbericht der Koniglichen Preuss. Akademie der Wiesenschaften zu Berlin.
Juli 1855—August 1856. 8vo.

Abhandlungen der Koniglichen Akademie der Wissenschaften zu Berlin. 1855, 4to.
Erster Supplement,—Band. 1854. Folio.

By

DONORS,

The Society,

The Institute.

Imper. Academy
of Vienna,

Ditto.

Ditto.

The Society.

The University
Library, Edin-
burgh.

The Registrar-

General.

The Registrar-
General.

The Society.
Ditio.

Sir Roderick
Murchison.

The Observatory.
The Institute.
The Author.
The Academy.

Ditto.

LIST OF DONATIONS.

DONATIONS.

April 20, 1857.

A General Catalogue of the Principal Fixed Stars, from Observations made at the
Hon. East India Company’s Observatory at Madras in the years 1830-43.
By T. Glanville Taylor, F.R.S. 4to.

Astronomical Observations made at the Hon. East India Company’s Observatory
at Madras, in the years 1843-47; together with the Recomputation of the
Sun and Moon, and Planetary Observations, since 1831. By T. Glanville
Taylor, F.R.S. 4to.

Astronomical Observations made at the Hon. East India Company’s Observatory
at Madras. By Capt. W. K. Worster and W. 8S. Jacob. 1848-52. 4to.

Revenue Meteorological Statements of the North-Western Provinces, for the several
Official years from 1844-45 to 1849-50. 4to.

Meteorological Register kept at the Hon. East India Company’s Observatory at
Madras. By J. Goldingham, F.R.S., and T. Glanville Taylor, F.R.S., for
the years 1822-43, Folio.

Transactions of the Royal Society of Literature. Second Series. Vol. v., Part 3.

Proceedings of the Royal Astronomical Society. Vol. xvii., No. 5. 8vo.

Monatsbericht der Koniglichen Preuss, Akademie der Wissenschaften zu Berlin.
8vo. November—December 1856.

Quarterly Journal of the Geological Society. 8vo. February 1857.

Journal of the Proceedings of the Linnean Society. 8vo. Vol. i., No. 4.

Silliman’s American Journal of Science and Arts, 8vo, March 1857.

Proceedings of the Berwickshire Naturalists’ Club. 8vo, Vol. iii., No. 7.

Transactions of the Cambridge Philosophical Society. 4to. Vol. ix., Part 4.

Essays and Heads of Lectureson Anatomy, Physiology, Pathology, and Surgery.
By the late Alexander Monro Secundus, M.D., F.R.S.E. With a Memoir
of his Life, and Copious Notes, explanatory of Modern Anatomy, Physiology,
Pathology, and Practice. By his Son and Successor. 8vo.

Army Meteorological Register from 1853 to 1854 inclusive, from Observations
made by Officers of the Medical Department of the Army, at Military Posts
of the United States. Prepared under direction of Brevet-Brigadier General
Thomas Lawson. 4to.

Statistical Report of the Sickness and Mortality in the Army of the United States,
from 1839 to 1855. By Richard H. Coolidge, M.D. 4to.

Reports of Explorations and Surveys to ascertain the most practicable and econo-
mical Route for a Railroad from the Mississippi River to the Pacific Ocean,
made in 1853-4. 4to. Vol. i.

Narrative of the Expedition of an American Squadron to the China Seas and Japan,
in the years 1852-54, under command of Commodore M. C. Perry, U.S. Navy.
By Francis L. Hawkins, D.D., LL.D. 4to. Vol. i. Also Vol. iii. of the
same work, being Observations on the Zodiacal Light from April 2, 1853, to
April 22, 1855. By Rev. George Jones, A.M. 4to.

699

DONORS,

Hon. E. I. Com-
pany.

Ditto.

Ditto.
Ditto.
Ditto.
The Society.
Ditto.
The Academy.
The Society.
Ditto.
The Editors.
The Club.

The Society.
Dr Monro.

Professor Henry
D. Rogers.

Ditto.

Ditto.

Ditto.

( 701r)

INDEX TO VOL. XXI.

A

Alkaloids (Vegetable), On the action of the halogen compounds of ethyl and amyl on some vege-
table alkaloids, 27.

Amides of the Fatty Acids, researches on, 299,

Anverson (Tuomas), M.D. Researches on some of the crystalline constituents of opium. Second
Series, 195. On the products of the destructive distillation of animal substances. Part Third,
219. Part Fourth, 571.

Animal Substances, products of their destructive distillation, 219, 571.

B

Batrour (Joun Hurron), M.D, On certain vegetable organisms found in coal from Fordel, 187.

Bennett (Joun Hucues), M.D. An investigation into the structure of the Torbanehill mineral,
and of various kinds of coal, 173.

Booz (Gxrorce), LL.D. On the application of the theory of probabilities to the question of the
combination of testimonies or judgments, 597,

Brown (James F.). Ona general method of substituting iodine for hydrogen in organic compounds,
and on the properties of iodopyromeconic acid, 49.

Buddhist Opinions and Monuments of Asia, compared with the symbols on the ancient sculptured
“ Standing Stones” of Scotland, 255.

C

Coal. An investigation into the structure of the Torbanehill mineral, and of various kinds of coal,
Ais:

Coal from Fordel, on certain vegetable organisms found in, 187.

Chinoline and its homologues, 377.

Cinchonine, on the volatile bases produced by the destructive distillation of, 309.

Colour. Experiments on colour as perceived by the eye, with remarks on colour-blindness, 275,

Combinations, on a problem in, 359.

Connett (A.), On a new hygrometer, or dew-point instrument, 15.

Crystalline Constituents of Opium, 195,

D

Davy (Joun), M.D. On the impregnation of the ova of the Salmonide, 1, Some miscellaneous
remarks on the Salmonide, 245, On the urinary secretion of fishes, with some remarks on
this secretion in other classes of animals, 543.

Diatomacee found in the Firth of Clyde and in Loch Fine, 473.
VOL. XXI. PART IV. 9B

702 INDEX.

Dynamical Top, for exhibiting the phenomena of the motion of a system of invariable form about a
fixed point, with some suggestions as to the earth’s motion, 559.

E

Earth’s Crust, on the laws of structure of the more disturbed zones of, 431.

English Lake District, on the meteorology of, including the results of experiments on the fall of
rain, the temperature, the dew-point, and the humidity of the atmosphere, at various heights
on the mountains, up to 3166 feet above the sea-level, for the years 1851, 1852, and 1853,
81.

Ethyl and Amyl, action of halogen compounds of, on some vegetable alkaloids, 27.

F

Fermat’s Theorem, 403.
Forses (James D.), D.C.L. Further experiments and remarks on the measurement of heights by the
boiling point of water, 235.

G

Grecory (Witt1Am), M.D. On new forms of marine Diatomacez, found in the Firth of Clyde and
Loch Fine, 473.

H
:

Heat, dynamical theory of, 123.

Heights, measurement of, by the boiling-point, 235.

How (Henry). On the action of halogen compounds of ethyl and amyl on some vegetable alka-
loids, 27.

Hygrometer. Ona new hygrometer, or dew-point instrument, 15.

I

Involuntary Muscular Fibre, on the minute structure of, 549.
Todine. A method of substituting hydrogen for iodine in organic compounds, 49.
Todopyromeconic Acid, 49,

K

Ke xanp (Rev. Purzir), M.A. On superposition, 271. On a problem in combinations, 359.

L

Lister (JosePH), F.R.C.S. On the minute structure of involuntary muscular fibre, 549.

M

Magnetic Declination. On errors caused by imperfect inversion of the magnet, in observations of
magnetic declination, 349.

Maxwett (James Cierx), B.A. Experiments on colour, as perceived by the eye, with remarks on
colour-blindness, 275. On a dynamical top, for exhibiting the phenomena of the motion of a
system of invariable form about a fixed point, with some suggestions as to the earth’s mo-
tion, 557.

INDEX. 703

Meteorology of the English Lake District, 81.

Mixer (Joun Frercwer), Ph.D. On the meteorology of the Lake District, including the results
of experiments on the fall of rain, the temperature, the dew-point, and the humidity of the
atmosphere at various heights on the mountains, up to 3166 feet above the sea level, for the
years 1851, 1852, and 1853, 81.

O

Opium, crystalline constituents of, 195.

Ts

Photometer, 363.

Ponton (Munco). On solar light, and on a simple photometer, 363.

Prismatic Spectra of the Flames of compounds of Carbon and Hydrogen, 431.

Probabilities, on the possibility of combining two or more probabilities of the same event, so as to
form one definite probability, 369. On the application of the theory of probabilities to the
question of the combination of testimonies or judgments, 597.

R

Rocers (H. D.), Hon, F.R.S.E. On the laws of structure of the more disturbed zones of the~
earth’s crust, 431.
Rowney (Tuomas H.), Ph.D, Researches on the amides of the fatty acids, 299.

S

Salmonide, on the impregnation of the ova of, 1.

Salmonide, miscellaneous remarks on, 245.

Solar Light, 363.

Solar System, mechanical energies of, 63.

Srewarr (Batrour). On a proposition in the theory of numbers, 407.

Sunlight. Note on the possible density of the luminiferous medium, and on the mechanical value
of a cubic mile of sunlight, 57.

Superposition, on, 271.

Swan (Wittram). On errors caused by imperfect inversion of the magnet, on observations of mag-
netic declination, 349. On the prismatic spectra of the flames of compounds of carbon and
hydrogen, 431.

T

Tarzot (H. F.), F.R.S. On Fermat’s theorem, 403.

Terror (Bishop). On the possibility of combining two or more probabilities of the same event,
so as to form one definite probability, 369.

Theory of Numbers, on a proposition in, 407.

Thermo-Electric Currents, 123.

Tuomson (Witt1am). Note on the possible density of the luminiferous medium, and on the mechanical
value of a cubic mile of sunlight, 57. On the mechanical energies of the solar system, 63. On
the dynamical theory of heat. Part V. Thermo-electric currents, 123.

~

“3.0 -
704. INDEX.

Torbanehill Mineral, 7, 173.
Trait (Tuomas §.), M.D. On the Torbanehill mineral, 7.

U

Urinary Secretion of Fishes, with some remarks on this secretion in other classes of animals, 543.

V

Vision. On the extent to which the received theory of vision requires us to regard the eye as a camera
obscura, 327.

W

Witutams (C. GREVILLE). On the volatile bases produced by the aigiruative distillation of cincho-
nine, 309. Researches on chinoline and its homologues, 377.

Witson (Gzorce), M.D. On the extent to which the received theory of vision requires us to regard
the eye as a camera obscura, 327.

Wise (Tuomas A.), M.D. Notes on some of the Buddhist opinions and monuments of Asia, com-
pared with the symbols on the ancient sculptured “ Standing Stones” of Scotland, 355.

+

END OF VOLUME TWENTY-FIRST.

NEILL & Co., Printers, Edinburgh.

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