\0 • \ '•H'V^

^•^S'.

THE

EDINBURGH NEW

PHILOSOPHICAL JOURNAL,

EXHIBITING A VIEW OFfHB

PROGRESSIVE DISCOVERIES AND IMPROVEMENTS

IN THB-; ^ - '

SCIENCES AND THE ARTS.

CONDUCTED BY

ROBERT JAMESON,

RKOIUS PROFBSSOR OF NATURAL HISTORY, LECTURER ON MINERALOGY, AND KBEPBR OP
THE MUSEUM IN THE UNIVERSITY OF EDINBURGH.
Fellow of the Royal Societies of London and Edinburgh ; Honorary Member of the Royal Irish Academy ; of the
Royal Society of Sciences of Denmark ; of the Royal Academy of Sciences of Berlin ; of the Royal Academy of
Naples ; of the Geological Society of France ; Honorary Membpr of the Asiatic Society of Calcutta ; Fellow of
the Royal Linnean, and of the Geological Societies of London ; of the Royal Geological Society of Cornwall, and
of the Cambridge Philosophical Society ; of the Antiquarian, Wemcrian Natural History, Royal Medical, Royal
Physical, and Horticultural Societies of Edinburgh ; of the Highland and Agricultural Society of Scotland ; of
the Antiquarian and Literary Society of Perth ; of the Statistical Society of Glasgow ; of the Royal Dublin
Society ; of the York, Bristol, Cambrian, Whitby, Northern, and Cork Institutions ; of the Natural History So-
ciety of Northumberland, Durham, and Newcastle ; of the Imperial Pharmaceutical Society of Petersburgh ; of
the Natural History Society of Wetterau ; of the Mineralogical Society of Jena ; of the Royal Mineralogical So-
ciety of Dresden ; of the Natural History Society of Paris ; of the Philomathic Society of Paris ; of the Natural
History Society of Calvados ; of the Senkenberg Society of Natural History ; of the Society of Natural Sciences
and Medicine of Heidelberg ; Honorary Member of the Literary and Philosophical Society of New York ; of
the New York Historical Society ; of the American Antiquarian Society ; of the Academy of Natural Sciences of
Philadelphia ; of the Lyceum of Natural History of New York ; of the Natural History Society of Montreal ; of
the Franklin Institute of the State of Pennsylvania for the Promotion of the Mechanic Arts ; of the Geological
Society of Pennsylvania ; of the Boston Society of Natural History of the United States ; of the South African
Institution of the Cape of Good Hope, &c. &c. &c.

OCTOBER 1838... APRIL 1839.
VOL. XXVI.

TO BE CONTINUED QUARTERLY,

EDINBURGH :

/ ADAM & CHARLES BLACK, EDINBURGH ;

LOlNGMAJS, ORME, BROWN, GREEN & LONGMANS, LONDON.

1839.

I

PRINTED BY NEILL & CO. OLD FISHMARKBT.

CONTENTS.

Page
Art. I. Historical Eloge of Joseph Fourier. By M. Arago,
Perpetual Secretary to the Academy of Sciences
of France, . . . . . 1

II. On the Natural History of Volcanos and Earth-
quakes. By Dr Gustav Bischof, Professor of
Chemistry in the University of Bonn. Commu-
nicated by thc; Author, . . . 25

1. Are Volcanic phenomena capable of a satisfactory
explanation from the increase of temperature to-
wards the centre of the Earth, or can Chemical
processes be admitted with greater probability to ^'

be the cause of Volcanic action ? . . . 25 5

1. The hypothesis, which ascribes Volcanic

phenomena to intense Chemical action,
shewn to be untenable, ... 26

2. The hypothesis which supposes the Tem-

perature of the Earth gradually to increase
towards the centre, to a red and white
heat, explains in a satisfactory manner
(according to the present state of science)
Volcanic phenomena as well as Earth-
quakes, 05

III. On Thunder and Lightning. By M. Arago, 81

1. Of Lightning, . . ... . .82

2. Sheet Lightning, 86

3. Concerning Ordinary Thimder, — the time between it

and the Lightning, — Thunder Claps, — the extreme
distance at which it may be heard, — the Thunder
of serene weather, — and of the Length of the Light-
ning's Hash, 91

CONTENTS.

4. Concerning the Odours developed by the Thunder-
bolt, .106

6. Lightning instantly melts many substances, and pro-
duces immediate vitrification, it shortens those me-
tallic wires along which it runs, and pierces holes
in the bodies it encounters in its progress, . .106

6. On the transportation of masses of matter effected

by Lightning, 107

7. Lightning cleaves wood in the direction of its length

into a number of thin laths, or into still smaller
fragments, „ 109

8. Upon the dangers which arise from Lightning, and

upon the means which at different times have been

used for protection, more especially conductors, 114

1. Are the dangers which arise from Lightning

so considerable as to merit consideration ? 114

2. On the means which mankind have em-

ployed for personal protection against
Lightning, . . . . . .124

3. When Lightning falls on Man or .Animals,

placed near each other, whether in a straight
line or in an unenclosed curve, it is gene-
rally at the two extremities of the line that
its effects are most intense.and hurtful, 132

4. Is the risk of being struck increased by run-

ning, during a thunder-storm ? . .138

5. Are the Clouds whence Thunder and Light-

ning are incessantly issuing so constituted,
as some natural philosophers suppose, that
it is very dangerous to traverse them ? 140

6. Does the Lightning strike before it becomes

visible? 143

IV. On the Geology of the Neighbourhood of Kelso.
By Charles Le Hunte, Esq. In a Letter to
the Editor, ..... 144

V. A singular mode of Propagation among the Lower
Animals illustrated. By Sir John Graham Dal-
YELL. Communicated by the Author, . 152

VI. On Geodetical Surveying and Trigonometrical Level-
ling. By WiLUAM Galbraith, Esq. M.S. A.,
Teacher of Mathematics in Edinburgh. Com-
municated by the Society of Arts for Scotland, 158

I

CONTENTS. Hi

VII. Notice of an erroneous Method of using the Theodo-
lite, with a strict Analysis of the effects of various
arrangements of Readers. By Mr Ejdward Sang,
F.R.S.E., M.S.A., Civil Engineer and Machine-
maker. Communicated by the Society of Arts
for Scotland, . . . .173

VIII. Chemical Views regarding the Formation of Rocks,
which seem to afford new arguments in favour of
Neptunism. By Professor and Mining Director
Nepomuk Fuchs of Munich, . . 182

IX. Description of several New or Rare Plants which
have lately flowered in the neighbourhood of
lEdinburgh, and chiefly in the Royal Botanic Gar-
den. By Dr Graham, Professor of Botany in
the University of Edinburgh, . . 194

X. Report of the Committee appointed by the Society of
Arts for Scotland, to award Prizes for Communi-
cations read and exhibited during Session 1837-
38, . . . . . .199

XI. Researches in Embryology. First Series. By Mar-
tin Barry, M.D., F.R.S.K., Fellow of the Royal
College of Physicians in Edinburgh, 203

XII. New Publications, .... 206

1. Sketch of the Civil Engineering of North America.

By David Stevenson, Civil Engineer. John
Weale, London, 1838 206

2. Memoirs of the Wemerian Natural History Society

for the years 1831-37. Vol. VII. With Thirty-five
Coloured Geological Sections, and a Coloured Geo-
logical Map ; and Sixty-seven Illustrative Figures
of Fishes. 8vo. Pp. 550, 1838. Black & Co.,
Edinburgh ; and Longman & Co., London. . 208

3. Insecta Lapponica descripta a Johanne Wilhelmo

Zetterstedt, 1 vol. 4to. Lipsiaoc. 1838. . . 209

4. Traits Elementaire de Conchyliologie, avec I'appli-

cation de cette science h la Gcognosie. Par G. P.
Deshayes. 8vo. Chez Crochard & Compie. Paris, 212

'V CONTENTS.

5. Dictionary of Arts, Manufactures, and Mines. By

Andrew Ure, M. D., F.R.S., &c. Nos. II. III.

IV 213

6. Journal of the Asiatic Society of Bengal. Edited by

]SIr Princep. No. LXXV. March 1838. Cal-
cutta J and Messrs W. H. Allen & Co. London. 213

7. Observations on the Genus Unio. By Isaac Lea,

Member of the American Philosophical Society,

&c. &c. &c. 4to. With numerous Coloured Plates, 213

8. Report of the Geological Survey of Connecticut. By

Charles Shepard, M.D. Pp. 188. Newhaven,
United States. 1837, 213

XIIL List of Patents granted in Scotland from 15th Sep-
tember to 14th December 1838, . . 214

CONTENTS.

Page

Art. I. Historical Eloge of Joseph Fourier. By M. Arago,
Perpetual Secretary to the Academy of Sciences
of France. (Concluded from p. 25.) . • 217

II. Remarks on the more important Atmospherical
Phenomena. By Professor Ludwig Friedrich
Kaemtz of Halle, . . • ^44

Importance of Meteorology, . . . • 244

Temperature of the Atmosphere, . • . • 246

Rise and Fall of the Barometer explained, . • 248

Winds, — Sea and Land Breezes, ... • • 250

Trade Winds, . . . • ^50

Winds in High and Low Latitudes, . . • 252

' Explanation of the Variable Winds, . . ■ 253

Moisture of the Atmosphere, ' . . . * 254

Dew, Hoar-Frost, Fog, Clouds, and Rain, . . 259

The Barometer and its connection with Temperature, 262
Influence of the Direction of the Wind on the" Baro-
meter, . . . . . . 265

Influence of the various Winds on the Weather, . 26 7

Prognostications of the Weather, . . .271

III. On Thunder and Lightning. By M. Arago. (Con-
tinued from p. 144.) . . . 275

Concerning the means, by the Aid of which it is pretended
that Edifices are protected against injury from Lightning, 275

Is it true that the Trees which overtop a house, at small
distances, free it from all risk of Lightning, a« many me-
teorologists pretend ? . . . 276

CONTENTS.

On the means by which it has been alleged, that whole
towns, and even great ranges of country, may be pre-
served from the injurious eifects of lightning, . 278
On the effects of great fires burning in the open air, 279
On the noise of cannon as a means of dissipating thunder
storms, ....... 281

Is it useful or dangerous to ring great bells during a thun-
der storm ? . . . . . . 286

IV. Reply to Professor Bischof s Objections to the Che-
mical Theory of Volcanos. By Charles Dau-
BENY, M.D., F.R.S., Professor of Chemistry and
of Botany, Oxford. Communicated by the Author, 291

V. Upon the alleged influence wiiich the Roughness and
the Polish of surfaces exercise upon the Emissive
power of Bodies, in reference to the Experiments
of Professor Sir John Leslie. By M. Melloni, 299
VI. Account of an Intermitting Brine Spring discharging
Carbonic Acid Gas, near Kissingen, in Bavaria.
By Professor Forbes. Communicated by the
Author, . . . 306

History of the Spring, . . ^ 309

Phenomenon of Intermittence, . . 313

Temperature of the Spring, . . 317

Products of the Spring, . . .322

VII. On a Method of obtaining the greatest possible de-
gree of Exactitude from the data of a Survey.
By Mr Edward Sang, F.R.S.E, M.S.A., Civil-
Engineer and Machine -maker, Edinburgh. Com-
municated by the Society of Arts, . 327

VIII. A Series of Facts and Observations respecting the
Natural Causes of Arborescent or Dendritic Fi-
gures in the two divisions of Animal and Vege-
table Structures, and in Mineral Formations. By
Sir Anthony Carlisle, F.R.S. Communicated
by the Author, . . . 344

IX. On the Natural History of Volcanos and Earth-
quakes. By Dr Gustav Bischof, Professor of
Chemistry in the University of Bonn. Communi-
cated by the Author. (Concluded from p. 81.) 347

X. On the Vibration of Suspension Bridges and other
Structures ; and the means of preventing Injury

CONTENTS. iii

from this cause. By John Scott Russell,
M.A., F.R.S.E., and Vice-President of the So-
ciety for the Encouragement of the Useful Arts
in Scotland. Communicated by the Society of
Arts, ... 380

XI. Meteorological Tables, . . 896

Abstract of Meteorological Observations for 1838, made
at Applegarth Manse, Dumfries-shire. By the Rev.
William Dunbar, . . 396

Abstract of a Meteorological Journal for 1838, kept at

Anderson's Institution, Elgin. By Mr Allan, 397

"Lord Gray's Meteorological Table for 1838, . 398

XII. Quantity of Saline Matter in Deep and Surface Sea-
water, obtained inLat. 0°33'N., and Long. 8^16' E.;
also Results of three Experiments on the Tempe-
rature of the Sea at great depths ; and state of the
Barometer and Thermometer during a gale of
wind off the Cape of Good Hope. Communicated
by Captain Robert Wauchope, R. N., . 390

XIII. Observations on Boots and Shoes, with reference

to the Structure and Action of the Human Foot.
By Mr Jambs Dowie, M.S.A. Communicated by
the Society of Arts, . . . 401

XIV. On the Mucilage of the Fuci, with Remarks on its

application to economical ends. By Mr Samuel
Brown junior, Haddington, . . 409

XV. On the Influence of Atmospheric Pressure on the

Tidal Waters of Cornwall and Devon, . 415

XVI. Description of several New or Rare Plants which
have lately flowered in the Neighbourhood of
Edinburgh, chiefly in the Royal Botanic Garden.
By Dr Graham, Prof, of Botany, . 419

XVII. Proceedings of the Royal Society of Edinburgh, 422

1. Discussion of one Year's Observations of Thermome-
ters sunk to diflFerent Depths in different localities in
the neighbourhood of Edinburgh. By Professor For-
bes. 2. On the Law which connects the Elastic Force
of Vapour with its Temperature. By John Scott
Russell, Esq. 3. Abstract of a Paper on Results
of Observations made with Whewell's New Anemo-
ter. By Mr John Ranken. Communicated by Pro-
fessor Forbes. 4. Notice respecting an Intermitting

iv CONTENTS.

Brine Spring discliai'ging Carbonic Acid Gas, near
Kissingen in Bavaria. By Professor Forbes. 5.
Notice on the Geology of Gottland, from the Obser-
vations of Mr Laing. By Dr Traill. 8. Notice
regarding some points in Hydrodynamics that have
been misunderstood. By Mr Scott Russell.

XVIII. Proceedings of the Wernerian Natural History So-
ciety. (Continued from vol. XXV. p. 199.) . 427

XIX. Proceedings of the Botanical Society of Edinburgh, 429

XX. New Publications, . . . 430

1. The Silurian System, founded on Geological Re-
searches, &c. ; by Roderick Impey Murchison,
Esq. F.R.S., &c. &c. &c. Two volumes quarto, with
numerous pictorial and geognostical engravings, and

a Geological Map. Murray, London. 1839. 430

2. A Sketch of the Geology of Fife and the Lothians,
including detailed Descriptions of Arthur's Seat and
Pentland Hills ; by Charles Maclaren, Esq.,
F.R.S.E. Post 8vo. pp. 235. 1839. Adam and Charles
Black, 431

3. Journal of the Asiatic Society of Bengal. Edited by
Mr Prinsep. — Numbers for April, May, June, and
July 1838; Calcutta; and Messrs W. H. Allen & Co.
London. . . . . . 432

4. Dictionary of Arts, Manufactures, and Mines ; by An-
drew Ure, M.D., F.R.S. Parts V, VI, VII. Long-
man & Co. . . . . . 433

5. Zoology of the Voyage of H. M. Ship Beagle, under
the Command of Captain Fitzroy, during the years
1832 to 1836. . . . . 433

6. Illustrations of the Zoology of Southern Africa, &c.
&c. By Andrew Smith, M. D., Surgeon to the
Forces, and Director of the Expedition into the In-
terior of Africa. 4to: Smith,. Elder and Company,
London, . 434

XXI. List of Patents granted for Scotland from 14th De-
cember 1838 to r5th March 1839, . 434
Index, . . . . . 439

Memoromdum.

Dr Goring and Mr Kenwood's Communications in next Number of

Journal.

THE

EDINBURGH NEW
PHILOSOPHICAL JOURNAL.

Historical Eloge of Joseph Fourier. By M. Aeago, Perpe-
tual Secretary to the Academy of Sciences of France.*

Gentlemen, — In former times academicians differed from
ieach other merely in the number, the nature, and the brilliancy
of their discoveries. Their lives, cast as it were in the same
mould, were made up of events little worthy of remark. A child-
hood more or less studious ; progress sometimes slow, sometimes
rapid ; inclinations thwarted by capricious or ignorant parents I
want of fortune and its accompanying privations ; thirty years of
a laborious professorship and abstruse studies ; — such were the
unpromising elements from which the admirable talent of the
former secretaries of the Academy was able to produce those
piquant, lively, and varied delineations which form one of the
principal ornaments of your learned transactions.

The biographers of the present day are not confined within
so narrow a range. The convulsions which France has expe-
rienced in freeing herself from the trammels of custom, super-
stition, and privilege, have cast amidst the storms of political
life, citizens of every age, rank, and character. Thus the Aca-
demy of Sciences has been represented by a glorious quota of
combatants and victims in the destructive arena, where, for
forty years, might and right were by turns triumphant.

Carry back your thoughts, for instance, to the immortal Na-
tional Assembly. You will find at its head a modest acade-
mician, a model of every private virtue, the unfortunate Bailly,
who, in the different phases of his political life, could conjoin a
passionate love of his country, with a moderation which even
his bitterest enemies were forced to admire.

* Read before the Academy of Sciences.
VOL. XXVI. NO. LI. JANUARY 1839. A

^ M. Arago^s Historical Eloge of Joseph Fourier,

When, at a later period, allied Europe launches against
France a million of soldiers ; when it is necessary to raise all
at once fourteen armies, it is the ingenuous author of the Essai
sur les Machines, and of the Geomctrie de position, who directs
this gigantic operation. It is also Carnot, our honourable
Jellow member, who presides during the incomparable campaign
of seventeen months, in which the French, novices in the art of
war, gain eight pitched battles, come off victorious in one hun-
dred and forty fights, occupy one hundred and sixteen fortified
places, and two hundred and thirty forts or redoubts, enrich our
arsenals with four thousand cannons and seventy thousand
muskets, make one hundred thousand prisoners, and cover the
dome of the Invalides with ninety flags. At the same time,
the Chaptals, the Fourcroys, the Monges, the Berthollets also
contributed to the defence of French Nationality ; some by ex-
tracting from our soil, by prodigies of industry, every particle
of saltpetre which it contained ; others by converting, by means
of new and rapid processes, the bells of towns, -.villages, and
even the smallest hamlets, into a formidable artillery, of which
our enemies naturally believed that we were destitute. At tlie
call of the country in danger, another academician, the young
and learned Meunier, willingly renounced the seductive occupa-
tions of the laboratory ; he went to gain renown on the ram-
parts of Konigstein, and to assist like a hero in the long defence
of Mayence ; and he fell at the age of forty, after having ob-
tained the first rank in a garrison which could boast of the
Aubert-Dubayets, the Beaupuys, the Haxos, the Klebers.

How could I here omit the last secretary of the old Academy.
Follow him in a celebrated assembly, in that convention whose
sanguinary delirium one might almost pardon, on recollecting
how gloriously terrible it was to the enemies of our independ-
ence, and you always see the illustrious Condorcet exclusively
occupied with the great interests of Ireason and humanity. You
hear him " execrate the shameful system of piracy which for
two centuries depopulated, by corrupting, the African conti-
nent ;" you hear him demand in accents of perfect conviction,
•^^ that our codes should be purified of that frightful capital punish-
ment, which renders the errors of judges for ever irreparable;
he is the official organ of the assembly on every occasion when

M. Arago's Historical Eloge of Joseph Fourier, 3

it is necessary to speak to the soldiers, to the citizens, to the
factions, or to strangers, a language worthy of France. He
spares no party, but continually calls to them " to think a little
less about themselves and a little more about the public affairs."
Finally, he replies to unjust accusations of weakness by acts
which leave, as his only alternative, poison or the scaffold.

The French revolution also drove the learned geometrician,
whose discoveries I am this day to celebrate, far from the path
which fate appeared to have marked out for him. In ordinary
times, it is of Do7n Joseph Fourier that the secretary of the
academy would have had to speak ; it is the tranquil and re-
tired life of a Benedictine which he would have unfolded to
your view. The life of our fellow member will be, on the con-
trary, stirring and full of perils ; it will be passed in the dan-
gerous disputes of the Forum ; amidst the chances of war ; a
prey to all the cares of a troublesome administration. This
life we shall find closely entwined with the great events of our
epoch. Let us hasten to add that it will be always praiseworthy
and honourable, and that his personal qualities will enhance
the brilliancy of his discoveries.

Fourier was born at Auxerre, on the 21st of March 1768.
His father, like that of the illustrious geometrician Lambert,
was nothing more than a tailor. This circumstance would
have formerly occupied a conspicuous place in the eloge of our
learned brother, — thanks to the progress of light, I can men-
tion it as an unimportant fact. Indeed, nobody now-a-days
believes, nobody pretends to believe, that genius is a privilege
attached to rank or fortune.

Fourier became an orphan at the age of eight years. A lady
who had remarked his engaging manners and happy disposition
recommended him to the bishop of Auxerre. By the influence
of this prelate, Fourier was admitted into the military school,
which was at that time under the direction of the Benedictines
of the congregation of St Maur. There he prosecuted his lite-
rary studies with astonishing rapidity and success. Several
sermons preached by the high dignitaries of the church, and
much admired at Paris, were from the pen of the scholar, then
twelve years old. It would now be impossible to revert to these

a2

4 M. Arago's Historical Eloge of Joseph Fourier.

iirst compositions of the youth of Fourier, as, when divulging
the plagiarism, he had the discretion never to name those who
pi'ofited by it.

Fourier had, when thirteen, the petulance and noisy vivacity
of most young people of that age, but his character changed
suddenly, and, as if by enchantment, from the moment that he
was initiated in the first notions of Mathematics, that is to say,
whenever he had become aware of his true calling. The regular
hours of study no longer sufficed for his insatiable curiosity.
Pieces of candles, carefully collected in the kitchen, and in
the corridors and the refectory of the college, served at night,
in a chimney corner shut in by a folding screen, to light the
solitary studies that were the prelude to those works by which,
a few years afterwards, Fourier was to do honour to his name
and his country.

In a military school directed by monks, the inclinations of
the pupils were likely to fluctuate only between two careers, —
the church and the army. Like D^ scartes, Fourier wished to
become a soldier ; like Descartes, :.j would, without doubt,
very soon have bepome tired of a garrison life ; he was not,
however, allowed to make trial of it. His request to undergo
an examination for the artillery, although strenuously supported
by our illustrious fellow member Legendre, was refused with a
cynical remark of which you yourselves shall judge; — " As
Fourier,"" replied the minister, " is not noble, he could not be
admitted into the artillery, although he were a second Newton !"

There is, gentlemen, in .the strict enforcement of regulations,
even when they are of the most absurd description, something
respectable, which I take pleasure in acknowledging. In re-
gard to this circumstance nothing could diminish the odious
nature of the ministerial words. It is not true, in point of fact,
that there was formerly no admission into the artillery, unless
for those who had titles of nobility ; — a certain degree of for-
tune often supplied the want of parchment. Thus, it was not
only something undefinable, and which, be it remarked, our
ancestors the Franks had not invented, that was awanting in
the young Fourier ; it was a certain amount of income whose
equivalent the men, at that time placed at the head of affairs,
would have refused to see in the genius of a second Newton I
Let us, gentlemen, preserve the remembrance of these things ;

M. Arago''s Historical Eloge of Joseph Fourier. 5

they shew in an admirable manner the immense progress which
France has made in the last forty years. Our descendants
will see in them, not the excuse, but tlie explanation of some of
the sanguinary disorders which stained our first revolution.

Fourier, not having been allowed to gird on the sword, took
the habit of a Benedictine, and retired to tha abbey of Saint
Bc7ioii'Sur-Loir, where he was to perform his noviciate. He
had not yet pronounced the vows, v/hen, in 1T89, delightful
and seductive ideas on the social regeneration of France seized
on all minds. Fourier immediately renounced the ecclesiasti-
cal career ; but this circumstance did not prevent his former
masters from intrusting him with the principal chair of Mathe-
matics at the military school of Auxerre, and lavishing on him
marks of lively and sincere affection. I may venture to say
that no circumstance in the life of our fellow member shews
more clearly the goodness of his disposition and the suavity of
his manners. We must be unacquainted with the human heart,
to suppose that the monks of Saint-Benoit did not feel some
displeasure at seeing themselves abandoned so abruptly ; or to
imagine, above all, that they renounced, v/ithout lively regret,
the glory which the order might expect from the ingenious fel-
low-labourer who was leaving them.

Fourier made a worthy return for the confidence of which he
had just been the object. When his colleagues were unwell,
the titular professor of Mathematics filled by turns the chairs
of Rhetoric, History, and Philosophy ; and, whatever was the
subject of his lectures, he dealt out with an unsparing hand, to
an audience who listened to him with delight, the treasures of
a varied and profound knowledge, adorned with all the orna-
ment which the most elegant language could give them. "

At the close of 1789, Fourier went to Paris, and read before
the Academy of Sciences, a memoir on the solution of numerical
equations of all degrees. This, his first youthful work, was, so to
speak, never lost sight of by our fellow member. He explained
it at Paris, to the pupils of the Polytechnic School ; he deve-
loped it on the banks of the Nile before the Institute of Egypt ;
at Grenoble, from the year 1802, it was the favourite subject
of his discussions with the Professors of the Central School, or

6 M. Arago's Historical Eloge of Joseph Fourier.

the Faculty of Sciences : this memoir, in fine, contained the
basis of the work which Fourier was engaged in printing at the
time of his death.

A scientific subject does not occupy so much space, in the
life of a learned man of the highest order, without possessing
importance and difficulty. The question of Algebraic analy-
sis, of which we have just made mention, and which Fourier
studied with such remarkable perseverance, is not an exception
to this rule. It presents itself in a great number of applications
of the calculus to the movement of the stars, or to the physics
of terrestrial bodies, and generally in the problems which lead
to equations of a high order. Whenever he wishes to leave the
region of abstractions, the calculator has need of the roots of
these equations ; thus, the art of discovering them by means of
an uniform method, whether exactly or approximately, naturally
early excited the attention of geometricians.

An attentive examination begins to discover some traces of
their efforts in the writings of the mathematicians of the school
of Alexandria. Those traces, it must be admitted, are so slight
and so imperfect, that it might almost be allowable for us not
to date the origin of this branch of analysis farther back than
the excellent works of our countryman Viete. Descartes, to
whom we render very incomplete justice when we content our-
selves with saying that he taught us much in teaching us to
doubt, also occupied himself for a short time with this problem,
on which he left the indelible mark of his powerful hand.

Hudde gave for a particular, but very important case, rules
to which nothing has been since added ; Rolle, of the Academy
of Sciences, devoted his whole life to this one question. Among
our neighbours, on the other side of the channel, Harriot, New-
ton, M'Laurin, Stirling, Waring, in fact all the illustrious geo-
metiicians whom England produced during the last century,
also made it the object of their researches. Some years after-
wards, the names of Daniel Bernoulli, Euler, Fontaine, were
added to this host of great names ; and at length Lagrange
entered on the career in his turn, and, at his very commence-
ment, substituted for the imperfect, although most ingenious
efforts of his predecessors, a complete and perfectly unobjec-

M. Arago's Historical Eloge of Joseph Fourier. 7

tionable method. From that instant the dignity of science
was vindicated ; but in such a case, we could not say with the
poet,

Le temps nefait rien d, Vaffaire.

Now, although the processes invented by Lagrange, simple in
their principle, and applicable to all cases, have theoretically
the merit of leading to the result with certainty, they would
require, on the other hand, calculations of a repulsive length.
It remained then to perfect the practical part of the question : it
was necessary to find means to shorten the process, without
rendering it less certain. Such was the principal object of the
researches of Fourier, and this object he attained in a great
measure. '

Descartes had already found, in the order according to which
the signs of the different terms of any numerical equation suc-
ceed each other, the means of deciding, for instance, how many
real and positive roots this equation may have. Fourier did
more : he discovered a method of determining how many posi-
tive roots of an equation are included between two given quan-
tities. Here certain calculations become necessary, but they
are very simple, and, whatever degree of precision be desired,
they lead without trouble to the required solutions.

I am doubtful if it is possible to mention a single scientific
discovery of any importance, which has not raised discussions
about priority. Fourier's new method of resolving numerical
equations, forms a striking illustration of this general rule. It
is proper, after all, to acknowledge that the theorem which serves
as the basis of this method was first published by M. Budan ;
that, according to a rule formally sanctioned by the principal
academiesof Europe, and from which scientific historians could
not deviate without falling into uncertainty and confusion, M.
Budan ought to be considered as the investor. I assert, how-
ever, with equal confidence, that it would be impossible to deny
to Fourier the merit of having attained his object by his own
efforts. I even regret, that in order to establish rights which
no one thought of denying, he should have j udged it necessary
to have recourse to certificates of former pupils of the Poly-
technic School, or of professors of the University. Since our

8 M. Arago's Historical Eloge of Joseph Fourier,

fellow member had the modesty to believe that his simple decla-
ration would not suffice, why, and this argument would have
been full of force, did he not shew to what extent his demon-
stration differs from that of his competitor ? An admirable de-
monstration in reality, and so imbued with the essential ele-
ments of the question, that a young geometrician, M. Sturm,
has just made use of it for establishing the truth of a beautiful
theorem, by means of which he determines, not only the simple
limits, but the exact number of roots of any equation, which
are included between two given quantities.

A short time ago we left Fourier at Paris, submitting to the
Academy of Sciences the analytical work of which I have just
given a general idea. On his return to Auxerre, the young
geometrician found the town, the surrounding country, and
even the school to which he belonged, busily occupied with the
great questions of human dignity, philosophy, and politics,
which were at that time debated by the orators of the different
parties in the National Assembly. Fourier also gave himself
up to this excitement. He enthusiastically embraced the prin-
ciples of the revolution, and joined with ardour in whatever
was great, just, and generous in the popular struggle. His
patriotism induced him to undertake the most difficult missions.
Let us mention that, even at the peril of his life, he never took
advantage of the base, sordid, and sanguinary passions which
were engendered on all sides.

As member of tlie popular society of Auxerre, Fourier pos-
sessed almost unlimited influence. There is one instance of it
which is still remembered throughout the whole of Burgundy,
On the occasion of the levy of 300,000 men, he made such elo-
quent use of the words honour, country, glory, and he persuaded
so many to enlist, that balloting was rendered unnecessary. At
the voice of the orsftor, the contingent assigned for the chief
place of the department of Yonne was formed, spontaneously
assembled within the very precincts of the assembly, and im-
mediately marched to the frontier. Unfortunately these strug-
gles in the forum, in which so many noble lives were at that
time wasted, were far from being always of real importance. Ri-
diculous, absurd, and burlesque notions continually jarred with
the inspirations of a pure, sincere, and enlightened patriotism.

M. Arago's Historical Eloge of Joseph Fourier. 9

The popular society of Auxerre would furnish us, if required,
with more than one example of these grievous contrasts. Thus
I may state that, within the same precincts where Fourier could
excite the honourable sentiments which I have had the pleasure
to mention, he had at another time to contend with a certain
orator, well intentioned perhaps, but assuredly a bad astrono-
mer, who, wishing as he said, not to leave it to the good plea-
sure of the municipal administrators, proposed that the names
Quarter of the North, East, South, and West, should be as-
signed by lot to the different parts of the town of Auxerre.

Literature, the fine arts, and the sciences, seemed for a time
to be likely also to feel the happy influence of the French re-
volution. See for instance, with what enlarged ideas the re-
form in weights and measures was conceived ; on what vast
operations they resolved to found it ; what geometricians, what
astronomers, what eminent natural philosophers presided over
all the parts of this great work. Alas ! fearful internal con-
vulsions soon began to throw a gloom over this magnificent
spectacle. The sciences could not prosper amidst the deadly
struggle of factions. They would have blushed to owe any
thing to the men of blood, whose blind passions sacrificed the
Sarons, the Baillys, and the Lavoisiers.

A few months after the 9th Thermidor, the Convention,
wishing to restore the country to ideas of order, civilization,
and internal improvement, thought of organizing a system of
public instruction; but where could they find professors.? The
religious establishments from which they were formerly chosen
were suppressed ; besides they had almost all emigrated. The
lay members of the teaching establishment having become offi-
cers of the artillery, the engineers, or the staff, were fighting
the enemies of France on the frontiers. Fortunately, during
this period of intellectual exaltation, nothing seemed impossi-
ble. Professors were awanting ; it was decreed that there should
be some immediately, and the Normal School was formed. Fif-
teen hundred citizens of all ages, sent by the chief towns, were
soon assembled together, not to study the different branches of
human knowledge in their ramifications, but to learn, under
the most celebrated masters, the art of teaching.

Fourier was one of these 1500 pupils. It will excite asto-

10 M. Arago's Historical Eloge of Joseph Fourier,

nishment, not without reason I admit, when I mention that he
was elected for Saint Florentin, and that Auxerre appeared in-
sensible to the honour of being represented at Paris by the most
illustrious of her children. But this indifference will be under-
stood, and those calumnies which were its cause will disappear
for ever, when I state that after the 9th Thermidor, the capi-
tal, and especially the departments, were a prey to a blind and
reckless reaction, as political reactions always are ; that crime
(its change of party did not make it less hideous) usurped the
place of justice ; that excellent citizens, and pure, moderate,
and conscientious patriots, were daily pursued by bands of hired
assassins, before whom the populace remained struck dumb with
terror. Such are, gentlemen, the formidable causes which, for
a short time, deprived Fourier of the votes of his fellow coun-
trymen, and converted into a partisan of Robespierre, the man
whom Saint Just, alluding to his mild and persuasive eloquence,
called a Patriote en musique ; him whom the Decemvirs so often
cast into prison ; him who, when the reign of terror was at its
height, gave, before the revolutionary tribunal, the assistance of
his extraordinary talents to the mother of Marshal Davoust,
who had been guilty of the crime, at that time unpardonable,
of sending some sums of money to emigrants ; him who, at Ton-
nerre, had the incredible audacity to lock up at the inn an
agent of the committee of public safety, whose secret he had
discovered, and thus found time to warn an honourable citizen
that they were going to arrest him ; him finally, who, boldly at-
tacking the bloodthirsty Proconsul, before whom all Yonne
trembled, made him appear a madman, and obtained his recall !
These are, gentlemen, some of the acts of patriotism, devoted-
ness, and humanity, which signalized the early youth of Fourier.
They were, as you have seen, repaid with ingratitude ; but
ought we to be astonished at it ? To hope for gratitude, which
could not be shewn without danger, would be to exhibit igno-
rance of human weakness, and to expose one's self to frequent
disappointments.

In the normal school of the Convention, debates sometimes
followed after the ordinary instructions. On these occasions
the parts were reversed, and the pupils questioned the profes-
sors. Some words spoken by Fourier in one of these curious

M. Arago's Historical Eloge cjf Joseph Fourier. 11

and useful meetings, sufficed to make him remarked. Thus
when the necessity of creating maitres de conference was felt,
all eyes were turned to the pupil of Saint Florentin. The pre-
cision, the clearness, and the elegance of his lectures, soon ac-
quired for him the^^unanimous applause of the fastidious and
numerous audience which was intrusted to his care.

When at the height of his scientific and literary fame, Fou-
rier fondly carried back his thoughts to the year 1794, and to
the sublime efforts which the French nation at that time made
for forming an establishment of teachers. If he had dared, the
title of pupil of the old normal school would have been the one
which he would have preferred to take. This school, gentlemen,
perished from neglect and want of support, and not, whatever
might be said, on account of some defects of organization, which
time and reflection would easily have remedied. Although its
existence was so short, it gave to scientific studies an entirely
new direction, which was attended hy the most important re-
sults. In supporting this opinion by som^ additional remarks,
I shall fulfil a task which Fourier would assuredly have im-
posed on me, could he have suspected that, along with eloquent
praises of his character and his works, there would be inter-
mingled, within these very precincts, and by one of his succes-
sors, warm criticisms on his dear normal school.

It is to the normal school of the Convention alone that we
must go back, if we wish to find the first public teaching of the
geomelrie descriptive, that beautiful discovery of Monge. It is
from it that it passed, almost without modification, to the Poly*
technic School, to all kinds of manufactories, and even the most
humble workshops.

From the normal school is also to be dated a true revolution
in the study of pure mathematics. Demonstrations, methods,
and important theories, buried in the academical collections,
then, for the first time, made their appearance before the pupils,
and incited them to remodel, on new bases, the works destined
for instruction.

With some few exceptions, the learned men capable of ad-
vancing the sciences, formerly formed in France a class totally
distinct from that of the professors. In calling to the profes-
sorships the first geometricians, the first natural philosophers.

12 M. Arago's Historical Elogc of Joseph Fourier.

and the first naturalists in the world, the Convention conferred
on the office of the instructor an unusual eclat, whose happy ef-
fects we still feel. In the e}'es of the public, a title which had
been borne by the La Granges, the La Places, the Monges,
and the Berthollets, became, with reason, e^ual to that of the
highest rank. If, under the empire, the Polytechnic School
numbered among its working professors counsellors of state,
ministers, and the president of the senate, it is only to be ex-
plained by the impetus given by the normal school.

Look at the professors in the old great colleges, almost con-
cealed behind their papers, reading from the chair, amid the
indifference and inattention of their pupils, discourses carefully
prepared, and which, each year, reappeared the same. Nothing
of this kind occurred at the normal school : oral discourses were
alone allowed. The authorities even went so far as to require
from the illustrious learned men who had the charge of teach-
ing, a formal promise never to deliver lectures which they had
committed to memory. Since that time the chair has become
a tribune whence the professor, identified as it were with his
hearers, sees in their looks, their gestures, and their appear-
ance, sometimes the propriety of hastening on, sometimes, on
the contrary, the necessity of returning back, of awaking the
attention by some incidental observations, and presenting under
a new form the idea which had not at first been clearly under-
stood. And do not imagine that the beautiful extempore dis-
courses with which the amphitheatre of the normal school re-
sounded, remained unknown to the public : short-hand writers,
paid by the state, took them down. Their papers, after being
revised by the professors, were sent to the 1500 pupils, to the
members of the convention, the consuls and agents of the re-
public in foreign countries, and to all the official people of the
districts. In comparison to the parsimonious and niggardly ha-
bits of our time, this certainly was prodigality. Yet no one
would repeat this reproach, however slight it may appear, if I
were permitted to point out within these very precincts, an il-
lustrious academician who had his mathematical genius reveal-
ed to him in an obscure provincial town by the lectures of the
normal school.

The necessity of stating the important, but now forgotten

M. Arago's Historical Eloge of Joseph Fourier. 13

services, for which the advancement of the sciences is indebted
to the first normal school, has detained me longer than I intend-
ed. I hope I shall be pardoned for it. The example, at any
rate, will not be contagious. Praise of time past, as you know,
gentlemen, is no longer in fashion. Whatever is said or print-
ed tends to the belief that the world is of yesterday. This opi-
nion, which allows each to attribute to himself a more or less
brilliant part in the great cosmogonic drama, is too much sup-
ported by vanity to have any thing to fear from the effects of
logic.

We have already said that the brilliant success of Fourier in
the normal school, obtained for him a distinguished place among
those whom nature has endowed in the highest degree with ta-
lents for teaching. Thus he was not forgotten by the founders
of the Polytechnic School : to which celebrated establishment
he was attached, at first witli the title of superintendent of the
course of fortification, and afterwards entrusted with the course
of analysis. Here he left behind him a vetierated memory, and
the reputation of a professor remarkable for clearness, method,
and erudition ; I may even add the reputation of a professor
full of grace ; for our fellow member has proved that this kind
of merit may be considered as not foreign to the teaching of
mathematics.

The lectures of Fourier have not been preserved. The jour-
nal of the Polytechnic School contains only one memoir by him
on the Principle (if Virtual Velocities. This memoir, which
had probably been the substance of a lecture, shews that the se-
cret of the great success of this celebrated professor, consisted
in the skilful combination of abstract truths, of interesting ap-
plications, and of little known historical details, drawn from the
original sources, a most uncommon thing in our time.

We are now arrived at the epoch when the peace of Leoben
brought back towards the capital the chief remarkable men of
our armies. Then the professors and pupils of the Polytech-
nic School had sometimes the high honour of being seated be-
side Generals Dessaix and Bonaparte. Thus every thing pre-
saged for them an active participation in the events which each
foresaw, and which, indeed, were not long delayed.

Notwithstanding the precarious state of Europe, the Direc-

14 M. A.rago's Historical Eloge of Joseph Fourier.

tory decided on depriving the country of its best troops, and
sending them forth on an adventurous expedition. To remove
to a distance from Paris the conqueror of Italy, and thus put an
end to the strong demonstrations of popular feeling which his
presence always called forth, and which, sooner or later, would
have become truly dangerous, was at that time the sole wish of
the five chiefs of the republic.

On the other hand the illustrious general did not merely
dream of the immediate conquest of Egypt ; he wished to re-
store the country to its ancient splendour, to increase its culti-
vation, perfect the processes of irrigation, create new branches
of industry, open numerous outlets for commerce, stretch out
a helping hand to the miserable population, deliver them from
the degrading yoke under which they had groaned for centu-
ries, and finally, to bestow on them without delay, all the bless-
ings of European civilization. Such great designs could not
have been accomplished with the mere materials of an ordinary
army. It was necessary to make an appeal to the sciences, li-
terature, and the fine arts ; it was necessary to ask the assist-
ance of some men of intellect and experience. Monge and Ber-
thoUet, both members of the Institute and professors of the Po-
lytechnic school, became, with this view, the chief recruiters for
the expedition. It may here be asked, did our fellow mem-
bers really know the object of the expedition .? I could not po-
sitively assert this, but I know, at any rate, that they were not
allowed to divulge it. We are going to a distant country ; we
shall embark at Toulon ; General Bonaparte shall command the
army ; such was, in form and substance, the limited confidence
so haughtily communicated to them. On the faith of such vague
information, and with the chances of a naval combat in the
distance, try at the present day to enrol a father of a family,
a learned man, already celebrated for useful works and placed
in some honourable situation, or an artist in possession of
the public esteem and confidence, and I am much mistaken
if you meet with any thing else than a refusal. But in 1798
France was just emerging from a terrible crisis, during which
her very existence had been frequently endangered. And who
was there, moreover, who had not been exposed to imminent
personal danger? Who, that had not himself seen truly despe-

M. Arago'*s Histoi'ical Eloge of Joseph Fourier. 15

rate enterprises brought to a happy conclusion ? Is more re-
quisite in order to account for that adventurous spirit, that
want of all care for the morrow, which appears to have been
one of the most striking features of the epoch of the Directory ?
Thus Fourier accepted, without hesitation, the offers which his
colleagues made to him in the name of the general-in-chief ; he
gave up the enviable office of professor in the Polytechnic
School to go — he knew not where, to do — he knew not what !

Chance placed Fourier during the voyage, in the same vessel
which carried Kleber. The friendship which the learned man
and the soldier vowed to each other from that moment, was not
without some influence on the events of which Egypt was the
theatre after the departure of Napoleon.

He who put as his signature to the orders of the day : *' Mem-
ber of the Institute, Commander-in-chief of the army of the
East," could not fail to consider an academy as one of the means
for the regeneration of the ancient kingdom of the Pharaohs.
The valiant army which he commanded had scarcely achieved
the conquest of Cairo in the memorable battle of the Pyramids,
when the Institute of Egypt was formed. It was to be composed
of forty -eight members divided into four sections. ]\Ionge had
the honour of being its first president. As in Paris, Bonaparte
belonged to the mathematical sections. The office of perpetual
secretary being left to the free choice of the members, was una-
nimously given to Fourier.

You have seen the celebrated geometrician discharging the
same duties in the Academy of Sciences ; you have appreciated
the extent of his knowledge, his enh'ghtened benevolence, his
constant affability, his straight-forward and conciliatory dispo-
sition. If you imagine as superadded to so many rare qualities,
that activity which youth and health alone can give, you will
have created anew the secretary of the Institute of Egypt, and
the likeness which I would make of him would grow dim be-
side the original.

On the banks of the Nile, Fourier gave himself up to assi-
duous researches on almost all the branches of knowledge com*
prehended within the vast range of the Institute. The Decade
and the Courrier de VEgypte mention the titles of his different
works. I observe among them a memoir on the general sola-

16 M. Arago's Historical Eloge of Joseph Fourier.

tion of algebraic equations ; researches on the methods of eli-
mination ; the demonstration of a new algebraic theorem ; a
memoir on indeterminate analysis; essays on general mechanics;
a technical and historical work on the aqueduct which con-
veys the waters of the Nile to the castle of Cairo ; remarks
on the Oases ; the plan of statistical researches to be made on
the state of Egypt ; the programme of the proposed excava-
tions on the site of the ancient Memphis, and throughout>the
whole extent of the tombs ; an account of the revolutions and
of the customs of Egypt since its conquest by Selim.

I find, moreover, in the Decade Egyptienne, that on the
first complementary day of the year VI., Fourier presented to
the Institute the description of a machine destined to facilitate
the process of irrigation, and which was to be moved by wind.

This description, so foreign to the ordinary current of our fel-
low member's ideas, has not been printed. It would naturally
find its place in a work, for which the expedition to Egypt might
still furnish the materials, notwithstanding the numerous and
beautiful publications to which it has given rise : this work would
consist in the description of the manufacture of steel, arms, pow-
der, cloth, machines, all of which our army had to make on the
spur of the moment. If, during our childhood, our interest is
Avarmly excited by the expedients which Robinson Crusoe falls
upon, to escape from the romantic dangers which are constantly
assailing him : how, when at a mature age, could we regard with
indifference, a handful of Frenchmen cast on the inhospitable
shores of Africa, without any possible communication with their
own country ; forced to struggle, at the same time, against the
elements and formidable armies ; in want of provisions, clothing,
arms and ammunition ; and supplying every thing by the power
of genius !

The great space which I have still to go over will scarcely
allow me to add a few words on the official services of the illus-
trious geometrician. As French commissioner to the divan of
Cairo, he had become the official organ of communication be-
tween the general-in-chief and any Egyptian who might have
any complaints to make of an attack against his person, pro-
perty, customs, habits, or religion. Manners always mild, scru-
pulous attention to prejudices which it would have been in vain

M. Arago's Historical Eloge of Joseph Fourier. 17

to oppose, and an inflexible love of justice, had given him an
ascendency over the Mussulman population, which the precepts
of the Koran scarcely left room to hope for, and which were
of great use in keeping up friendly relations between the
inhabitants of Cairo and the French soldiers. Fourier was
especially an object of veneration among the Sheiks and the
Ulemas. A single anecdote will shew that this sentiment was
caused by the liveliest gratitude.

The Emir Hadji, or chief of the caravan, whom General
Bonaparte had appointed on arriving at Cairo, made off during
the campaign of Syria. There were at that time very strong
reasons for believing that four Sheiks Ulemas were accom-
plices in the treason. On returning to Egypt, Bonaparte en-
trusted the examination of this serious affair to Fourier. Do
not propose half measures to me, said he ; you have to deal
with great personages : you must either cut off their Tieads or
invite them to dinner. The day after this conversation the
four Sheiks dined with the General-in-Chief. In following the
dictates of his heart, Fourier not only performed an act of hu-
manity, it was also excellent policy. Our learned fellow mem-
ber, M. Geoffroy Saint Hilaire, from whom I have the anec-
dote, says, in proof of this, that Soleyman el Fayoumi, the
principal of the Egyptian chiefs, whose punishment, thanks to
our fellow member^ was so happily changed to a banquet, took
every occasion among his countrymen of praising French gene-
rosity.

Fourier shewed no less skill when our Generals entrusted him
with diplomatic missions. It is to his finesse and his suavity
that our army was indebted for a treaty of alliance, offensive
and defensive, with M our ad Bey. Fourier, justly proud of the
result, neglected to make known the details of the negociation.
This is deeply to be regretted, for the plenipotentiary of Mou-
rad was a woman, the same Sitty Neji(;ah whom Kleber has
immortalized by celebrating her benevolence and her noble
character in the bulletin of Heliopolis ; and who, moreover,
was already renowned from one end of Asia to the other, on
account of the bloody revolutions which her matchless beauty
had caused among the Mamelukes.

The unequalled victory which Kleber gained over the army

VOL. XXVI. NO. LI. JANUARY 1839. B

l8 M. Arago's Historical Eloge of' Joseph Fourier.

of the Grand Vizier, did not crush the energy of the Janissa-
ries, who had seized on Cairo whilst the fighting was going on
at Heliopohs. They defended themselves from house to house
with, such heroic courage, that the French had only to choose
between the entire destruction of the town and an honourable
capitulation for the besieged. The latter was determined on :
Fourier, entrusted as usual with the negociation, carried it
through successfully ; but this time the treaty was not dis-.
cussed, agreed on, and signed, within the mysterious precincts
of a harem, on soft divans under the shade of balmy groves.
The parley took place in a house half demolished by cannon
balls and grape shot, in the centre of the quarter whose pos-
session the Janissaries bravely disputed with our soldiers, be-
fore a truce could be agreed on even for a few hours. Thus,
when Fourier was preparing to welcome the Turkish commis-
sioner according to the oriental custom, numerous shots were
fired from the opposite house, and one of them pierced through
the coffee-pot which he held in his hand. Without wishing to
call in question the bravery of any one, do you not think, gen-
tlemen, that if diplomatists were generally placed in as dange-
rous situations, the public would have less cause to complain of
their proverbial delays .?

To unite under one point of view all the official services of
our indefatigable fellow member, I should still have to call
your attention to him on board the English fleet, at the period
of the capitulation signed by Menou, stipulating for various
conditions in favour of the members of the Institute of Egypt ;
but services not less important, although of a different nature,
also claim our attention. They oblige us to retrace our steps,
to return to the epoch of glorious memory, when Desaix com-
pleted the conquest of Upper Egypt, as much by the wisdom^
the moderation, and the inflexible jiustice of all his actions, as
by the rapidity and boldness of his military operations. Bona-
parte at that time sent two numerous commissions to explore,
in these remote regions, a number of monuments whose exist-
ence was scarcely suspected by the moderns. Fourier and
Costaz were the commanders of these commissions ; I say the
commanders, as they had been provided with a tolerably im-
posing military force ; for it was often after a combat with the

M. Arago's Historical Eloge of Joseph Fourier. 19

wandering Arab tribes, that the astronomer found, in the posi-
tion of the stars, the materials for a future map, — that the na-
turalist discovered unknown vegetables, determined the geolo-
gical constitution of the country, or engaged in laborious dis-
sections,— that the antiquary measured the dimensions of the
buildings, and tried to copy exactly the fantastic images with
which every thing in that singular country was covered, from
the smallest articles of furniture, and the simple playthings of
chikU-cn, to immense palaces, to those enormous fa9ades, along-
side of which the largest modern constructions would scarcely
deserve notice.

The two learned commissions examined with scrupulous care
the magnificent temple of the ancient Tentyris, and especially
the series of astronomical signs which have been the cause of
such warm debates in our days ; they also studied the remark-
able monuments of the mysterious and sacred Isle ofElphan-
tina, the ruins of Thebes with its hundred gates, before which
(and they were only ruins) our whole army stopped to express
its feelings of admiration.

Fourier was still engaged, in Upper Egypt, superintending
these memorable works, when the General-in-Chief suddenly
quitted Alexandria, and returned to France, accompanied by
his principal friends. Those then were deceived, who, not see-
ing our fellow member in the frigate Le Muiron, along with
Monge and Berthollet, imagined that Bonaparte had not pro-
perly appreciated his eminent qualities. If Fourier did not
join in the voyage, it was because he was a hundred leagues
from the Mediterranean when the Muiron set sail. This ex-
planation is less interesting, but it is true. At all events, the
friendship of Kleber for the Secretary of the Institute of Egypt,
the proper influence which he allowed him to exercise on a
number of delicate occasions, would have amply compensated
for any mimerited slight.

I now come, gentlemen, to the epoch, of grievous memory,
when the Agas of the Janissaries, who had taken refuge in
Syria, despairing of vanquishing our admirably commanded
troops in honourable and open warfare, had recourse to the
cowardly stiletto. You are aware that a young fanatic, whose
imagination had been excited in the mosques by a month of

b2

20 M. Arago's Historical Eloge of Joseph Fourier.

prayer and fasting, inflicted a mortal wound on the hero of
Heliopolis, at the very instant he was, with his usual kindness,
listening, without distrust, to the recital of pretended wrongs,
and promising redress.

This ever-to-be-lamented misfortune plunged our colony in
-deep affliction. The Egyptians themselves mingled their tears
with those of the French soldiers. From a delicacy of senti-
ment, which we are wrong in supposing the Mahometans des-
titute of, they did not forget at that time, indeed they have
never since forgotten, to state that the assassin and his three
accomplices were not born on the banks of the Nile.

The army, in order to assuage its grief, desired that the ob-
sequies of Kleber should be performed with great pomp. It also
wished that, on that solemn day, they should receive an account
of the long series of brilliant actions, which will hand down the
name of the illustrious general to our latest posterity. By una-
nimous agreement, this honourable and difficult duty was en-
trusted to Fourier.

There are very few men, gentk/.ien, who have not seen the
brilliant dreams of their youth vanish, one after the other,
amid the sad realities of advanced age. Fourier was one of
these rare exceptions to this rule.

Carry back your thoughts to the year 1789, and inquire what
the future promised for the humble neophyte of Saint Benoit
sur Loir. Undoubtedly a little literary glory ; the good for-
tune to be allowed to speak occasionally in the public places of
the capital ; or the satisfaction of being entrusted with the pane-
gyric of some person or other of official celebrity. Well ! nine
years have scarcely passed away, and you find him at the head
of the Institute of Egypt, the oracle and idol of a body which
numbered among its members Bonaparte, BerthoUet, IMonge,
Malus, GeofFroy Saint-Hilaire, Conte, &c. You see the generals
continually entrusting him with the charge of relieving them
from difficulties apparently insurmountable, and even the army
of the cast, so I'ichly supplied with men of talent, desiring no
other orator when they wish to celebrate the great actions of
the hero whom they had just lost.

It was on the breach of a bastion recently carried by assault
by our troops, in view of the most majestic of rivers, of the

M. Arago''s Historical Eloge of Joseph Fourier. 21

magnificent valley which it fertilizes, of the frightful desert of
Libya, and of the colossal pyramids of Gizeh ; it was in pre-
sence of the twenty different races included within the vast cir-
cumference of Cairo, before the bravest soldiers that ever trod
that soil, where, nevertheless, the names '^of Alexander and
Caesar are still famous ; it was in the midst of all which could
affect the heart, elevate the thoughts, and excite the imagina-
tion, that Fourier unfolded to view the noble life of Kleber,
He was listened to with religious silence ; but very soon^
addressing the soldiers ranged in order of battle before him,
lie exclaims, *' Ah ! how many of you would have aspired
to the honour of throwing yourselves between Kleber and his
assassin ! I call you to witness, intrepid cavalry, who rushed
to save him on the heights of Koraim, and instantaneously dis-
persed the numerous enemies who had surrounded him."" At
these words, the whole army are as it were electrified, the colours
are lowered, the ranks close, arms clash against each other, a
deep groan bursts from thousands of breasts covered with sabre
and shot wounds, and the voice of the orator is drowned in
sobs.

A fevf months afterwards, on the same bastion, and before
the same soldiers, Fourier celebrated, with no less eloquence,
the exploits and virtues o^ the general whom the conquered
tribes in Africa saluted by the flattering name of Sultan juste,
and who had just sacrificed his life at Marengo to insure the
triumph of the French arms.

Fourier only quitted Egypt with the last remains of the
army, after the capitulation signed by Menou. On his return,
to France, his first and most constant occupations had for their
object the illustration of the memorable expedition, of which he
liad been one of the most active and useful members. The idea
of collecting into one focus the various works of all his brother
members undoubtedly belongs to him. I find this proved by
an unpublished letter, written to Kleber from Thebes, the
20th vendcmiaire, year vii. No public document in which men-
tion is made of this great literary monument is of prior date.
The Institute of Cairo, on adopting, after the month ofyj*?-
maire, year viii., the project of a work on Egypt, entrusted

£2 M. Arago's Historical Eloge of Joseph Fourier.

Fourier with the charge of uniting together and arranging the
scattered materials, and of writing the general introduction.

This introduction was published under the title of Preface
Historique. Fontanes said that there were united in it les graces
cTAthenes et la sagesse de VEgypte. What could I add to such
praise ? I shall only say that we find in a few pages the prin-
cipal features of the government of the Pharaohs, and the re-
sults of the subjection of ancient Egypt by the kings of Persia,
the Ptolomies, the successors of Augustus, the emperors of
Byzantium, the first Cahphs, the celebrated Saladin, the Ma-
melukes, and the Ottoman Princes. The different phases of
our adventurous expedition are described in particular with the
greatest care. Fourier carries his scruples so far as to try to
prove that it was legitimate. I have only said to trij, for on
this point the second part of the praise accorded by Fontanes
might be somewhat diminished. If, in 1797, our countrymen
experienced at Cairo or Alexandria, outrages and extortions
which the Sultan either would not or could not repress, it may
assuredly be admitted that France ought to obtain justice for
herself, that she had the right to send a powerful army to bring
the Turkish custom-house officers to reason. But it is a very-
different thing to allege that the Divan of Constantinople should
have encouraged the French expedition, that our conquest was,
in some measure, to restore Egypt and Syria to it, and that the
-taking of Alexandria and the battle of the Pyramids would add
to the renown of the Ottoman name. However, the public has-
tened to absolve Fourier from whatever was doubtful in this
small part of his beautiful work. They sought its origin in
political necessity. In plain terms, they thought they saw, be-
hind certain sophisms, the hand of the former gen eral-in- chief
of the army of the East !

Napoleon, then, would appear to have shared, by giving ad-
vice or even imperative commands, in the composition of Fou-
rier''s paper. What was not long ago merely a matter of plau-
sible conjecture, has now become an incontrovertible fact.
Thanks to the kindness of M. Champollion-Figeac, I had
very lately in my hands some parts of the first proofs of the
Preface Historique. These proofs were sent to the Emperor,
who wished to look carefully over them before reading them

M. Arago's Historical Eloge of Joseph Fourier. 23

along with Fourier. They aie covered with marginal notes,
and the additions which were made in consequence, extend to
nearly a third part of the original discourse. In the sheets, as
in the work finally given to the public, we remark the com-
plete absence of proper names ; the only exception is for the
three generals-in-chief.

I may add, that in no part of these precious proofs, belong-
ing to M. Champollion, do we perceive any traces of the mi-
serable sentiments of jealousy which have been attributed to
Napoleon. It is true that the Emperor, pointing to the word
illustrious, as applied to Kleber, said to our fellow member,
somebody has made vie remarl' this epithet ; but after a short
pause, he added, it is agreed that you shall leave it, for it is
just and well merited. These words, gentlemen, honoured the
monarch even less than they stained with infamy the somebody^
whom I regret I cannot name otherwise, but who belonged to
those vile courtiers whose whole life is passed in studying the
weaknesses and bad passions of their masters, in order to make
them the means of arriving at honours and fortune !

Immediately after his return to Europe, Fourier was ap-
pointed (2d January 1802) Prefect of the department of Isere.
The old province of Dauphiny was at that time a prey to vio-
lent political dissensions. The Republicans, the partizans of
the emigration, and those who had ranged themselves under
the banners of the Consular Government, formed as many dis-
tinct parties, between whom any reconciliation seemed impos-
sible. Well, gentlemen, Fourier effected this impossibility.
His first object was to get the hotel de la prefecture considered
as neutral ground, where each might shew himself without even
the appearance of concession. Curiosity alone at first attracted
a crowd to it ; but the crowd returned, for, in France, it rarely
deserts the salons where it finds a polite and affable host, ta-
lented without fojipery, and learned without pedantry.

What had been divulged about our fellow member's opinions
as to the antibiblical antiquity of the Egyptian monuments,
caused in particular lively apprehensions among the religious
party ; but they were dexterously informed, that the new pre-
fect had a saint in his family, and that the blessed Pierre
Fourier, founder of the establishment of Nuns connected with

^4 M. Arago's Historical Eloge of' Joseph Fourier,

the congregation of Notre Dame, was his grand uncle. This
circumstance effected a reconciliation which was every day more
and more strengtliened by the steady respect shewn by the
chief magistrate of Grenoble to all conscientious opinions.

As soon as he was assured of a truce between the religious
and political parties, Fourier was enabled to devote himself
without reserve [to the duties of his office. He did not consi-
der these duties to consist merely in accumulating documents
without limit and without utility. He took personal cogni-
zance of the projects which were submitted to him, and became
the indefatigable promoter of all those which were objected to
from prejudiced motives. We ought to rank among this latter
class the splendid road from Grenoble to Turin by Mount Ge-
nevre, which the events of 1814 so unfortunately interrupted ;
and especially the draining of the marshes of Burgoin.

These marshes, which Louis XIV. had given to Marshall
Turenne, were a focus of infection to the thirty-seven communes
whose lands they partly covered. Fourier directed in person
the topographical operations which proved the possibility of
draining them. With the documents in his hand, he went from
village to village, — I might almost say from house to house, to
arrange about the sacrifice which each family ought to make
for the general interest. By means of discretion, tact, and pa-
tience, " en prenant Vepi dans son sens et jamais a rebours^''
thirty-seven municipal councils were induced to sign a common
document, without which the projected operations could not
even have been commenced. Success rewarded this extraordi-
nary perseverance. Rich crops and pastures, numerous flocks,
and a robust and happy population, now cover an immense dis-
trict, where formerly the traveller did not dare to stop even a
few hours.

One of the predecessors of Fourier in the office of Perpetual
Secretary to the Academy, once thought it necessary to offer
an excuse for having given a detailed account of certain re-
searches of Leibnitz which had not required great efforts of in-
tellect : " We ought,"*' said he, " to be much obliged to such a
man, when he deigns, for the public advantage, to do something
which does not require genius." I do not understand such
scruples : in the present day, the sciences are too highly valued

Prof. Bischof 07i Volcanos and Earthqtiakes. 25

to allow of any hesitation about assigning the first rank to the
works which do them honour, and which spread comfort, health,
and happiness, among the working classes.

In the presence of a part of the Academie des inscriptions^
within the precincts where the name of Hieroglyphics has so
often resounded, I cannot omit to mention the service which
Fourier rendered to the sciences in preserving ChampoUion for
them. The young professor of history to the Literary Faculty
of Grenoble, had just reached the age of twenty. Fate calls
him to shoulder the musket. Fourier exempts him on the
ground of the title of pupil of the School of Oriental Langua-
ges, which ChampoUion had had at Paris. The Minister of
War learns that the pupil had formerly given in his resigna-
tion ; he exclaims against the fraud, and sends a furious order
for his departure, which seems to prevent even the idea of re-
clamation. Fourier, however, is not discouraged; the steps
he takes are skilful and urgent ; and finally, he draws such an
animated picture of the precocious talent of Ms young friend^
that it obtains from the authorities a special decree of exemption.
It was not easy, gentlemen, to be so successful. At the same
period a conscript, a member of our Academy^ could only get his
order for departure recalled, by declaring that he would fol-
low on foot and in the dress of the Institute, the contingent of
the arrondissement of Paris in which he was classed.
( To be concluded in next Numher.)

On the Natural History of Volcanos and Earthquakes^ by Dr
GusTAv Bischof, Professor of Chemistry in the University
of Bonn. Communicated by the Author.
I. Are volcanic phenomena capable of a satisfactory explanation frmn
the increase of temperature towards the centre of the earth., or can che-
mical processes be admitted icilh greater probabilit?/ to be the cause
of volcanic action ?

On inquiring into the cause of volcanic phenomena we must
not forget, says Von Humboldt,* that the arrangement of vol-

* On the structure and action of volcanos in various parts of the earth,
in the Abliandhmgen der Kouigl. Acad. d. Wissensch. zu Berlin, 1822 and
1823, p. 137, and in Jameson's Phil. Jour. vol. v. p. 222.

26 Prof. Bischof on the Natural History of

canos sometimes in circular groupsand sometimes in double lines,
is the most decided proof that their action is not dependent on
any trifling causes, lying near the surface, but that they are vast
and deeply-seated phenomena. Thus, for example, the whole
of the high country of Quito is one volcanic hearth, of which
the mountains of Pichincha, Cotopaxi, and Tunguragua, form
the summits. The subterranean fire breaks out sometimes from
one sometimes from another of these vents, which are usually
considered as distinct volcanos. The earthquakes, with which
America is so dreadfully visited, are also remarkable proofs of
the existence of subterranean communications, not only between
countries free from volcanos, as has been long known, but also
between volcanic hearths situated at a great distance from each
other. All these circumstances prove that the forces do not act
at the surface of the crust of the earth, but that, proceeding
from the interior of our planet, they communicate contempo-
raneously by fissures with the most distant points on the sur-
face.*

Two hypotheses may be proposed respecting the causes of vol-
canic phenomena. The one supposes them to be occasioned by in-
tense chemical actions taking place between bodies having a very
great affinity to each other, and by which so great a heat is pro-
duced, that lavas melt and are forced to the surface of the earth
by the pressure of elastic fluids. According to the other, the
earth at a certain depth is at a white heat, and this heat is the
chief cause of volcanic phenomena.

1. The hypothesis f which ascribes volcanic phenomena to intense chemi
col action^ shewn to he untenable.

AVe will not detain our readers with an account of the earlier
hypotheses, which derive volcanic phenomena from the action of
iron upon sulphur, or from the combustion of pyrites or coal,
as their insufficiency is self evident. But Davy's discovery of the
metallic bases of the alkalies and earths was considered as
throwing a great light on this subject.

This distinguished philosopher, who instituted some very
interesting experiments at Vesuvius during its eruptions in

* Von Humboldt's Reisen in die Equinoctial Gegenden des neuen Conti-
nents, t. i. p. 49G, t. iii, \\ 24, 2G, and 40, offer many instances of this kind.

Volcanos and Earthquakes. 27

1814, 1815, 1819, and 1820, endeavoured to explain the
phenomena by the oxidation of the metals of the alkalies and
earths.* He thinks himself justified in supposing the caverns
beneath the Solfatara of Fitzzuoli to have a subterranean
communication with Vesuvius, because whenever the latter is
tn action, the former is in repose. A slip of paper which
Davy threw into the mouth of the Solfatara, during an erup-
tion of Vesuvius, was not rejected, from which he concluded
that there must be a descending current of air. The subterra-
nean thunder, which is heard at such great distances from be-
neath Vesuvius, seems to him to indicate the existence of great
subterranean caverns, filled with gaseous substances, and that
the same caverns which, during the activity of the volcano, con-
tinue for a long time to eject enormous quantities of aqueous
vapour, must be filled, during its repose, with atmospheric air.
In proof of the existence of extensive caverns, he mentions those
in the limestone of Carniola. Now, as the metals of the earths
in the supposed volcanic caverns are not only exposed to the ac-
tion of the air but also to that of aqueous vapour, they will
be oxidized at the expense of both, and be converted into lava.
He thinks his hypothesis capable of explaining all the phenc-
mena which he observed.

Davy also touches upon the circumstance, often mentioned
by geologists, that almost all great volcanos are situated near
the sea.t Supposing their first ei'uption to have been caused
by the action of the sea-water upon the metals of the earths,
and the metallic oxides, ejected from the craters in the form of
lava, to have left vast caverns, the succeeding eruptions would
be effected by the oxidations which would ensue in those ca-

* Sur les Phenom^nes des Volcans. Annalcs de Cliim. et de Pliys.
vol. xxxvii. p. 133.

t Tlvat volcanos may act at a great distance from the sea is proved by the
Pesckan in the centre of Asia, whicli is 2G0 geographical miles distant from any
great sea, and from which streams of lava have issued within the period of
our history. Even the opinion that the vicinity of extensive lakes operates
on the volcanos of Central Asia, in the same manner as the ocean, isunfomid-
ed. The volcano of Tiirfan is surrounded by very mconsiderabie lakes, and
the lake of Temartu or Tssikul, wliich is not twice as large as the Lake of Gt'
nera, lies fully 25 geographicjd miles from Pesckan. See oleo Girardin in ojv
position to Davy's hypothesis in Jameson's Phil. Journ. vol. ix. py ia€.

S8 Prof. Biscliof on the Natural History of

verns. Davy is of opinion that when volcanos lie at a distance
from the sea, as those of South America, the water may be fur-
nished from subterranean lakes ; for Von Humboldt asserts that
some of these volcanos cast up fish.

If we wish to ascribe volcanic phenomena to chemical action,
says Davy, the oxidation of the metals of the earths and alka-
lies merit our attention in preference to any other process. He
himself, however, observes, that the observations in mines and
in hot springs seem to indicate, with some degree of probability,
that the interior of the earth possesses a very high tempera-
ture, and that, if the earth's nucleus be supposed in a state of
fusion, the explanation of volcanic phenomena is simpler than
according to his own theory.

Gay Lussac very justly remarks, that it is impossible to con-
ceive the admission of atmospheric air into the focus of volca-
nos, as there must be a force within them acting outwards, by
Avhich the liquid lava, a substance about three times as heavy
as water, is raised to a height of above 3000 feet, as at Vesu-
vius, and more than 9000 feet in many other volcanos. A
pressure of 3000 feet of lava, equal to that of a column of wa-
ter of 9000 feet high, or to about 300 atmospheres, necessarily
prevents the entrance of air into the interior of the volcanos ;
and as this pressure continues for many years, during which
time the phenomena by no means abate in activity, it is im-
possible that air should in any way contribute to it.

The presence of water in volcanos during the various stages
of their activity is, on the other hand, a circumstance repeatedly
witnessed by all observers.* Even the smoking during their
intervals of repose is, for the most part, nothing but a disen-
gagement of aqueous vapour. Violent eruptions are not un-
frequently followed by such enormous quantities of steam, that
it condenses in the atmosphere, and falls in heavy showers, as
was the case after the memorable eruption of Vesuvius, which
destroyed Torre del Greco in 1794.-(* Among the elastic fluids

* See, among others, Monticelli and Covelli, der Vesuv. Deutsch bear-
beitet von Noggerath and Pauls. Elberfeld, 1824, p. 167.

t See von Buch's geognostisclie Beobaolitungen, torn. ji. 152. There is,
however, still another cause, which occasions these heavy showers, as we
shall shew afterwards.

Volcanos and Earthquakes. 29

evolved from volcsinosj besides aqueous vapour, we frequently
find sulphureted hydrogen gas, as, for example, from those at
the equator ; and from others, as Vesuvius^ muriatic acid gas.
But the formation of these gases in the interior of volcanos
cannot be conceived without the presence of water.

If the oxidation of the earthy and alkaline metals were to take
place at the expense of water, enormous quantities of hydrogen
would be necessarily evolved during volcanic eruptions. But
this gas seems never to issue from volcanos. According to the
observations of Breislak,* Spallanzani,-}* Monticelli and Co-
velli, X Hoffmann, § and Poulett Scrope, || flames are never
seen to rise from the crater of Vesuvius, Neither did Gay-Lus-
sacH during his stay at Naples in 1805, during which he was
a frequent witness of explosions, which raised the fluid lava to
a height of above 600 feet, ever observe a combustion of hy-
drogen gas. Each explosion was accompanied with dense black
columns of smoke, which would have inflamed, had they been
composed of hydrogen gas, as they were traversed by bright
red-hot masses. According to Boussingault, neither hydrogen,
muriatic acid gas, nor nitrogen gas, is evolved from the volcanos,
under the equator, in the New World.** In opposition to
this evidence, we have the assertions of Von Buch. -f-f-

Davy's hypothesis does not account for the exhalations of
carbonic acid gas (Mofettes), which not only succeed every
eruption of Vesuvius, but also occur in the vicinity of extinct
volcanos and in places affording unquestionable traces of for-
mer volcanic action (Auve7-gne, Vivai'ais, Eifel, Laacher See,
Bohemia, and so forth,) % % in amazing quantities, and as far as
wecan learn from history, with uninterrupted uniformity. These

* Lelirbuch der Geologie, transl. into German by Strombeck, vol. iii.
p. 117. t Voyages dans les Deux Siciles etc. vol. ii. p. 31.

X Loco cit. p. 191. § A personal communication.

!l Considerations on Volcanos. London 1825.

H Loco cit. p. 420. * * Anal, de Cliim. et de Phys. t. Hi. p. 23.

ft Loco cit. t. ii. p. 14 1.

tit Monticelli and Covelli, 1. c. p. 191. Biscliof and Noggerath in Schwoig-
ger's Journ. v. xliii. p. 28. Bischof in Schweigger-Seidel's Journ. v. xxvi.
p. 120. The same in his Vulcanischen ^lineralquellen. Bonn. 1826, p. 251.
Von Buch in Poggendoi*ff's Ann. v, icii, p. 418«

so Prof. Bischo^ oji the Xatural History of

phenomena must necessarily be closely connected with volca-
nic action, and cannot pass unnoticed.

But these disengagements of carbonic acid gas could not
take place in the presence of atmospheric air in those vast sub-
terranean cavities without their mixing together. Yet, accord-
ing to Monticelli and Covelli,* the Mofettes of Vesuvitcs con-
tain but little atmospheric air, which seems not to intermix with
the carbonic acid gas until it reaches the surface. I have exa-
mined many such exhalations of carbonic acid gas, in the vi-
cinity of extinct volcanos (in the neighbourhood of the Laa^
cher See and in the Erfel) as well as in places where there are
no immediate volcanic traces {Himdsruck, the eastern declivity
of the Teutoburger Wald), and, in general, have found a scarcely
measurable quantity of atmospheric air. According to Bous-
singault,-|- the elastic fluids, which are evolved from the vol-
canos at the equator in the New World, consist of a great
quantity of aqueous vapour, carbonic acid gas, sulphureted
hydrogen gas, and sometimes fumes of sulphur ; he considers
sulphurous acid gas and nitrogen, on the other hand, as acci-
dental. This philosopher! also found tlie same gases,, viz., caa*-
bonic acid and sulphureted hydrogen gas, in the springs which
rise in the vicinity of these volcanos. All this is by no means
favourable to the supposition of the existence of vast subter-
ranean cavities filled with air under the craters, and an equally
unfavourable circumstance is, that, according to Boussingault,
no nitrogen is evolved from the volcanos under the equator,
which must necessarily be the consequence of oxidation at the
expense of atmospheric air.

Independently of all this, the metals of the earths have been
found by more recent experiments to be by no means so easy
of oxidation as Davy''s hypothesis assumed. Besides, this prone-
ness to oxidation must be supposed to be a property more es-
pecially belonging to the metals of silica and alumina, as these
earths together with oxide of iron, are the principal components
of volcanic products, — lavas, basalts, &c., generally amounting
to about O.S, whilst lime and alkalies, although never entirely
wanting, form but an inconsiderable proportion. But Berze-

* Loco cit. p. 194. t Loco cit. v. lii. p. 5. X Ibid. p. 181.

Volcanos and Earthquakes, 31

lius* haB shewn, that silicium, the combustible base of silica,
when freed of hydrogen by being gradually heated to a white
heat, is incombustible even at that heat in the air or in oxygen ;
and that it is equally incapable of decomposing water. In like
manner Wiihlerf found, that aluminum, the metallic base of
alumina, is not oxidized under a red heat, and decomposes hot
water but very slowly, while on cold water it has no influence
whatever.

Therefore Davy'^s hypothesis would be applicable only to the
metallic bases of alkaline earths and alkalies. But, as these oc-
cur only in small proportions in the volcanic rocks, it is scarce-
ly conceivable that so much heat should be evolved by their
combustion at the ordinary temperature as would be sufficient
to melt the pure earths, or to inflame their metals, supposing
them to exist at the seat of the volcanic action.

The shght specific gravity of the metals of the alkalies, also
proves fatal to Davy^s hypothesis ; for, i£ the mean density of
the earth surpass that of all kinds of rocks, those metals can-
not exist, at least not in great quantities, in the interior of the
earth.J Davy's hypothesis, therefore, according to the present
state of science, will not account for volcanic phenomena. §

Gay-Lussac,|| assuming that water supplied the oxygen in
volcanos, endeavoured to account for the absence of uncombined
hydrogen among the exhalations of volcanos, by supposing it
to form such combinations with other bodies as would not in-
flame by coming into contact with the air. This is the case
when it combines with chlorine to form muriatic acid gas. He
here refers to the observations of Breislak,^ and of Monti-

* Poggend. Ann. v. i. p. 221. f Ibid. t. xi. p. 146.

X Also the latest experiments, made with admirable exactness by Pro-
fessor Reich in Freiberg^ with tlie assistance of the torsion-balance, liave
given 5.44 for the density of the earth, as a mean of 14 experiments which
afforded very nearly the same results. Yersiiche Uber die mittlere Dichtig-
keit der Erde mittelst der Drehwage von F. Reich. Freiberg 1838. This
j-esnlt accords very nearly with that, which was found by Cavendish and
Hutton.

§ Davy, however,, afterwards abandoned his hypothesis. See Consola-
tion ia Travel, or the Last Days of a Philosopher.

II Loco cit. ' IF Loco cit. iii. p. 57 and 94.

32 Prof. Bischof o?i the Natural Histori/ of

celli and Covelli,* which shew that this acid is among the ex-
halations of volcanos. He himself, however, observes, that an
enormous quantity of muriatic acid must be evolved from the
craters, if the hydrogen, which would result from an oxida-
tion by means of water, were to enter into combination w^ith
chlorine. But it would be strange that such an exhalation
should not have been remarked sooner. In order to account
for the formation of muriatic acid, he mentions the experi-
ments made by him and Thenard, in which they evolved that
acid, by introducing aqueous vapour into a mixture of sand and
common salt heated to a red heat. In support of his position,
he mentions the occurrence of common salt in the lavas, from
one of which (that of Vesuvius in 1822), Monticelli and Covelli
extracted more than 0.09, and in the slags which cover the
white hot lava, and which sometimes contain very beautiful
crystals of salt. He farther notices the spongy lavas which con-
tain so much iron-glance, and is of opinion that this may also
be a consequence of the sublimation of chloride of iron, and its
subsequent decomposition, by coming in contact with aqueous
vapour and atmospheric air, while at a red heat.-h And, lastly,

* L. c. p. 172. See also Daiibeny's Description of Active and Extinct
Volcanos. Lond. 1826, p. 372, and v. Humboldt's Reise, etc. t. i. p. 195.

+ We may here notice the formation of artificial crystals of oxide of iron
in a potter's furnace. PoggendoriF's Ann. v. xv. p. 630. Mitscherlich, who
gives an account of this, finds an analogy between this formation and similar
ones in volcanos. He explains it by supposing that common salt and steam
both act together upon silica or siliceous combinations, and form muriatic
acid, and that this comes either alone or with a small quantity of Avater
into contact with oxide of iron, or ferriferous combinations. Thus chloride
of iron is formed, which is again decomposed by the aqueous vapours, and,
if the decomposition proceed slowly, the oxide of iron remains behind in
large crystals.

In some volcanic eruptions, the conditions necessary for the formation of
iron glance seem, indeed, to have been vei-y frequent, whilst in others they
have been entirely wanting. It is not only the lavas of Vesiimus^ Aci-rcale
in Sicily f and the rents in the lava of Stromholij which contain distinct cry-
stals of iron-mica ; but it is also found in the greatest abundance in Auvergney
{Vohic J Mont d* Or, Puy de Dome, etc. . . . ). On the other hand, it has
never been found by Noggerath in the volcanic masses of the Siebengeblrgc,
the Laacher See, and the El/el ; it has only lately been found that some of
the slags of the Boderhcrg, an extinct volcano, about two leagues distant from
Bom J are scantily covered with iron-glance. See Thomso der vulkanische

Volcanos and Earthquakes, 33

he mentions that chloride of iron, in contact with water, becomes
so exceedingly hot, that it is capable, in large quantities, of
raising itself to a white heat, and that the chlorides of silicium
and aluminium must be able to produce a much more extra-
ordinary degree of heat.

It cannot be denied that there is some justness in these con-
clusions. But it must be remembered, on the other hand, that
the premises are only taken from appearances at Vesuvius,'^
and that the occurrence of common salt and muriatic acid in
the products and exhalations of volcanos, seems by no means
to be general. We have already quoted Boussingault's obser-
vation, that muriatic acid is not evolved from the volcanos
under the equator in the New World. The hot springs in those
regions contain but little common salt.i* In my frequent ex-
cursions in the vicinity of the Laacher See and in the Ejfel, I
have never found any efflorescence of salt either on the undis-
turbed or fresh broken lavas, and other products of the extinct
craters in those districts. On the uncovered walls of trass, in
the Brohl valley, efflorescences are, indeed, to be found, but
they contain chlorides only as very subordinate ingredients.^
The lixiviation of trass, basalt, and other volcanic rocks, also
gives but a trace of common salt.|| That muriatic acid must
have played a very insignificant part in the eruptions of these
ancient volcanos, seems to be proved by the mineral springs
which rise in their vicinity ; for common salt is one of their
least considerable components, indeed they frequently contain
mere traces of it. This is the result of more than forty analyses
of mineral springs in those regions, which I have undertaken
during these last few years. But these waters would extract

Hodorborg, &c. Bonn, 1835, p. 22. It is worthy of notice, and speaks in
favour of the probability of the above-mentioned production of iron-glancc',
that in the places last mentioned, the appearance of combinations of cliloriiio
is very limited.

* The observations of Von Humboldt, Gay-Lussac, Von Buch, and Mon*
ticelli, made at different times, shew also that the exhalations of mu-
riatic acid are very variable. They are sometimes so frequent as to sur-
pass the exhalations of sulphurous acid, sometimes only a few trac^^fe of it
are found.

t Loco cit. p. 181. X Die vulkanischen Mineralquelleu, &c. p. 243.

II Idem, p. 246 and 277.

VOL. XXVI. NO. LI. JANUARY 18S9. C

34 Prof. Bischof on the Naiiiral Historij of

the chlorides from the volcanic masses through which they flow,
if they existed.in any considerable quantities in them, and would
return impregnated with them to the surface.

From all this we do not seem to be justified in considering
the chlorides as the chief agents in volcanic phenomena, al-
though it cannot be denied that tliey may, in some instances,
co-operate in their production.* It has even been supposed
that the beds of rock-salt are of volcanic origin. But this
proves nothing more than that rock-salt may have been raised
from the interior of the earth by volcanic power, and that the
beds of salt are a consequence of volcanic action, but not con-
versely, that chlorides and the disengagement of muriatic acid
are the cause of that phenomenon.

Now, since neither any process of oxidation, nor processes in
which chlorides take an active part, are capable of affording a
satisfactory explanation of volcanic phenomena, we can scarcely
conceive any other powerful chemical process, which could alone
give rise to them. We may, therefore, look upon the hypo-
thesis which seeks the cause of volcanic phenomena in intense
chemical action as untenable.

* Many volcanos have produced considerable quantities of common salt,
as, for instance, Vemt'm?, Hecki, &c. Also sal-ammoniac is found among the
volcanic sublimations of Vesutius and Etna, and almost exclusively in some
volcanos of the interior of Asia. Yauquelin found in a porous rock, con-
stituting a considerable part of the Puy de Sarcouy, in the chain of the Fny
de Dome, 0.055 of muriatic acid, which is worthy of remark in connection with
the freqvient occurrence of iron-glance in that neighbourhood. (Ann.des JIus.
vi. p. 98.) There are felspar crystals in the trachyte, coloured sulphui-
yellow by muriatic acid vapours of a former time. Common salt also
forms the chief ingredient in the thermal springs of St Nectaire, in the de-
partment Pay de Dome. In the mineral springs of Mont d'Or, Vichy, Chaudcs-
Aignes, Vah, &c. on the contrary, it is in very small quantities. In tlie
lavas of Etna 0.01 of muriatic acid has been found. In basalt, Kennedy found
0.01 ; Klaproth 0.0001 ; and I, 0-00085 of muriatic acid. I also found tliat
acid in a steatitic substance in the trachyte-conglomerate of the Siehenyebinje.
See " Die vulcanischen Mineralquellen," p. 277. But this occurrence of
juuriatic acid, which may, perhaps, be found in many other volcanic
productions, is far too inconsiderable for us to ascribe to it any great part
jn the production of volcanic phenomena. Proust tells us that, according
to Garicas Fernandez, the celebrated salt-mines at Poza, near Burgos, in Old
(kigtHe, are situated in the centre of a crater, in which the latter collected
various volcanic products. Joura. de Phys. vol. Iv. p. 457.

Volcanos and Earthquakes. 35

II. The hypothesis ichkh supposes the temperature of the earth (jradu-
allf/ to increase towards the centre, to a red and white heat, explains
in a satisfactory manner (according to the prresent state of science)
volcanic phenomena as well as eao'thquakes.

If the heat of the earth continually increases with the depth,
the rocks must at a certain depth be in a state of fusion. But
since they possess such various degrees of fusibility, the more
fusible rocks must be in a liquid state, at depths in which the
less fusible ones are still solid. At certain depths there must,
consequently, be masses of melted rocks, enclosed in the solid
rock, in the same manner as iron ores are melted and reduced
in the less fusible masses of which blast furnaces or crucibles
are composed. These depths must, according to the above hypo-
thesis, be looked upon as the seat of volcanic action. The crys-
talline rocks are the most easy of fusion on account of their
containing alkalies, which indeed are not wanting in any of
them. So that, in general, the more abundantly alkaline mine-
rals, as felspar, mica, leucite, &c., are contained in volcanic
masses, the more readily will they fuse.*

Sir James Hall-f- has endeavoured to ascertain the degree of
fusibility of various lavas and other volcanic rocks. Lava from
Vesuvius of the year 1785, melted at 18° of Wedge wood's py-
rometer, lava from Torre del Greco not till 40°. But their fu-
sibility varied very considerably, according as the melted lava
liad been cooled rapidly to a glass, or more slowly to a stony
crystalline mass. Thus, for example, those two lavas, when in
the form of a glass, both melted at the same degree (18°), whilst
the lava of 1785 was less fusible than that of Torre del GrecOy
when of a stony nature. :[ I*rom other appearances it may,
in general, be concluded, that the fusibility of lavas is between

* According to Von Buch (Abhaudlungen d. Kbnigl. Acad. d. Wissen-
schaften zu Berlin, 1818-1819, p. 62) it may be taken as a general rule, that
all real lavas, which flow in streams down the sides of volcanoes, eontaia
gliissy felspar. Vemtius being the only exception out of so many is not
Avorth mentioning.

t Transact, of the Roy. Soc. of Edinburgh, vol. v. &c.

X Glass is well known to be acted upon in a similaa* manner. When c«)Ji-
vorted, by being melted and slowly cooled again, into Reaumur's porcelain,
it comes less fusible.

SQ Prof. Bischof on the Natural History of

that of silver and copper. Thus in the lava which destroyed
Torre del Greco, some gold and a few copper coins were found
unmelted ; but the silver coins were melted and baked together
with some copper coins.* Davy found that a copper-wire of
2^5 of an inch in diameter, and a silver-wire of ^^ of an inch,
thrust into the lava near its source, instantly melted.-|- A wire
of copper J of an inch in diameter, which I held in a stream of
fused basalt, flowing out from a furnace, melted immediately.
But the basalt was doubtless heated far above its fusing point.
Now according to Daniel,^ silver melts at 2253° F., but copper
at 2548° F. ; we may therefore take a mean of 2282° F.
(=1000° R.) for the melting point of lava.

Now, if we suppose the increase of temperature to con-
tinue to follow the same progression as has been discovered in
accessible depths, the lava must be in a state of fusion, accord-
ing to the observations near Geneva and in Cornwall, at the
depth of about 113505 feet, and from those in the Erzgebirge
at about 126829 feet below the level of the sea near Vesuvkis
or Etna.§

If we suppose steam to be the power by which the lavas are
raised from this enormous depth, and by which the volcanic
bombs, rapilli, and ashes are thrown up, and according to all
observations hitherto made, water in its elastic state seems to
be the only means by which the lavas jl and other volcanic

* Thompson : Notices of an English Traveller, &c. Breislak. (Voyage dans
la Camp., vol. i. p. 279) mentions, that when bell-metal was plunged into tlie
lava, the zinc melted ont, leaving the copper behind.

+ Annal. de Chim. et de Phys. vol. xxxviii. p. 138.

X Journ. of Science, xxiii.

§ According to my observations made on a cooling basalt-ball of twenty-se-
ven inches diameter, and which I shall communicate afterwards, the increase
of temperature from the surface towards the centre of the earth, seems to
take place, not in an arithmetical, but in a geometrical progression. But the
exponent of this progression being but very little greater than 1, this progres-
sion comes very near to an arithmetical one. The depths, above calculated^
being but insignificant in proportion to the diameter of the globe, no great
error has been committed in supposing the increase of temperature follows
an arithmetical progression as far as these depths. With this exception, we
can hardly hope ever to become acquainted with the true progression of the
increase of the temperature to the interior. Therefore all such calculations?
as the former, can but give approximations to tlie truth.

11 Von Humboldt's Reise, t. i, p. 186. A short time before the great erup-
tion of VesutiuSf in the year 1805, he and Gay-Lussac observed that the wa-

Volcanos and Earthqiiahcs. 37

rocks,* are so raised ; it is yet a question whether its expan-
sive force could be sufficiently raised by heat ? Parrot-f- reckons
that the temperature of lava, at the moment of its ejection, is
five times as great as would be necessary to raise it 48000 feet
by the elastic force of steam, supposing the steam to be formed
in the presence of water. But from more recent inquiries on
the elastic force of aqueous vapour, this calculation must un-
dergo considerable corrections. The formula of Mayer, as al-
tered according to the last results of the experiments at Vknna%
corresponds the most nearly with the elastic force of steam as
actually observed, so that it may be considered as the most cor-
rect determination of its elasticity at higher temperatures. If
we wish to find the pressure of the steam in Paris inches of a
column of mercury from this formula, we shall have

log ^= 2.8316686 + log (213 ^t)— ^^^

in which t is the temperature in degrees of Reaumur = _ p «

tery vapours in the interior of the crater did not redden litmus. Many-
other naturalists have also found that the outlets of smoke of the Peak of
Ti'ncr'iffe emitted pure water only. Voy. de La Peyrouse, t. iii, p. 2. Hoffmann,
in liis letter to Von Buch on the geognostical structure of the Llpari Islandy,
in Poggondoi*ff's Annal. vol. xxvi, p. 9 and 45, and in several places in his ac-
count of the volcanic island which rose in the Dledlternmcan Sea, vol. xxiv,
p. 65. According to Monticelli and Covelli, tlie smoke which rises from the
lava-streams consist almost exclusively of aqueous vapour. Loco cit. p. 27,
05, and 83. Numerous fumaroles (exhalations of aqueous vapour) rise on
tlie island of hchia out of the cracks in the lava. Forbes in Edinb.
Journ. of Science, N. S. iv, p. 326. Reinwardt, Verhaudlingen van liet
liataviaasch genootsthap van Kunsten en Wetonschapen, negende deel,
l>atavia 1823, p. 1. Ordinaire mentions, in his "Histoire Naturelle dcs Vol-
cms," a mass of melting iron having been cast to a height of 150 feet, out
of a blast furnace, by some w^ater having accidentally got into it. See D'Au-
1)uisson, Traite de Geognosie, v. i, p. 215.

* 'J'he water contained in basalt speaks in favour of this opinion. See
Klaprotli's Beitriigo, &c., vol. iii, p. 249, and Kennedy in Appendix to the
same, p. 255. On melting basalt, and introducing a gun-barrel into the cru-
cible, I observed a considerable evolution of aqueous vapour.

t Grundriss der Physik der Erde imd Geologic. Riga u. Leipzig, 1815,
p. 264.

t Arzberger in the Jalirbiichem des Polytechnischen Instituts, vol. i
]). 144.

§ On steam and steam-engines in the Abhandluugen der Kunigl. tcch-
nischen Deputation fiir Gewerbe, part i, p. 344.

38 Prof. Bischof on the Natural History of

It is clear that the elastic force of steam cannot surpass a
certain maximum, which it reaches when its density is equal to
that of water. This is the case when the elasticity of the va-
pour e = 232952 Paris inches of mercury, or nearly 8320 atmo-
spheres, which suppoees a temperature of 2786° P.*

Thus, if aqueous vapour were to reach its greatest possible
elasticity, its temperature must exceed that above assumed for
the melting point of lava by 504° F. The highest column of
lava, which steam at its maximum elasticity is capable of sup-
porting, is, therefore, if we suppose the specific gravity of liquid
lava three times as great as that of water, 88747 feet. But a teni-
perature of 2786° F. will, according to the observations at Ge-
neva and in Cornwall^ be met with at a depth of 1 59265 feet,
and according to those in the Erzg-ebirge, at a depth of 155613
feet (about thirty English miles) below the level of the sea
near Vesuvius or Etnarf-

Supposing, then, the values found for the maximum
elasticity of steam for the corresponding temperature, and for
the depth at which that temperature must exist, to be correct,
it would not be possible, that a column of lava, of the whole
height, from the seat of the volcanos to the surface of the
earth, should be raised up. On the other hand, in the same
manner as a bubble of air let into a barometer, drives the
mercury into the Torricellian vacuum far above the barome-
tric height, aqueous vapour may raise a column of lava of
a height equal to its expansive force into the channels open-
ing into the craters. Thus, then, it may happen that aqueous
vapour, though far from its maximum elasticity, may yet
be able to raise a column of lava equal in height to its elas-
ticity from still greater depths to the surface of the earth.
A continual alternation of columns of lava and steam in
the channels may be very well conceived, the consequence of
which would be an alternate ejection of lavas, red hot masses,

* On steam and steam-engines in the Abliandlungen der Konigl. tech-
nischen Deputation fiir Gewerbe, part i. 344.

t Siijiposing the mean ten-} erature of this locality = Cl° F.

:

I

Volcanos and Earthquakes. 89

and clouds of steam, just as Spallanzani,* Scrope,f and Hoff-
mann, j observed on StrovihoU.

We have now to examine the circumstances under which
water might find its way to the origin of volcanic action. The
difficulties which present themselves when we suppose a direct
communication between the sea and the seat of the volcanos,
have already been discussed by Gay-Lussac. We shall make
an attempt to solve these difficulties.

M we imagine the sea to have free access by means of fis-
sures to the seat of the volcanos, the depth of which, according
to the above calculation, may be taken at from 113505 to
1^*6829 feet, the elastic force of steam at that depth, where
t = 2282'' F,, will be = 5310 atmospheres. But the hydrostatic
pressure of these columns of water is only from 3547 to 3963
atmospheres. The expansive force of steam at that depth in
which the temperature is 2282° F. is, therefore, greater than
the hydrostatic pressure opposed to it, so that the latter can-
not resist it. But since, as the temperature decreases, this
expansive power diminishes more rapidly than the hydrostatic
pressure, there must be a certain depth and a corresponding
temperature in which thev will be in equilibrium. For a con-
stant increase of temperature of 1° F. in 51 ft., this point will be
at the depth of 88044 ft. below the surface of the sea, where

* Voyag. t. ii. p. 21.

t Considerations on Volcanos, &c. p. 54. A plienomenou obsarved by
Sci-ope during the nigbt in the crater of Stroniholi distinctly shows, that, by
the force of aqueous vapours alone, the column of lava is raised. The lava
once suddenly disappeared in the depth of the crater ; on the contrary, in-
numerable little columns of steam appeared at the edges of the mouth of
the crater, which arose with a hissing noise. This lasted for some minutes,
when the molted mass rose again from beneath, and the phenomenon
pursued again its ordinary course. Spallanzani remarks very justly with a
view to this, that the compressed vapours prevented from being discharged
by the sinking lava which had become tenacious on the surface, will now es-
cape laterally through the fissures in the walls of the edge of the crater, and
in this case the laVa cauuot be elevated by them. It is not until the lava has
been sufficiently heated and become again liquid, that the vapour can rise
again ^ith the lava, and that the phenomenon can be re-established.

ij: Loco cit. p. 9. — D. Curbeto also observed that a dense smoke always
followed the streams of lava which were ejected on the 7th June 1731,
Von Buch in the Abhandl. d. Berliner Acad, of 1818-1819, p. 77.

40 Prof. Bischof 071 the Natural History of

the temperature is 1754'^5 F. ; " for, according to the above
formula, if t be taken equal to 1754°.5, e — 77028 inches of
a column of mercury, or l^iLil = 275 1 atmospheres, and MiLiA
gives the same number. On the other hand, for a constant in-
crease of temperature of 1° F. in 57.1 ft. it advances to a depth
of 105627 ft. below the surface of the sea, where the corres-
ponding temperature would be 1881°.5 F. ;* for the same for-
mula gives e ■=. 92435 inches of a column of mercury, or 3301
atmospheres, when t — 1881 °.5, and \^SiU. gives the same
value. Presupposing the correctness of the premises, these
calculations shew the possibility of columns of lava of M|i-1
= 29348 and ISH^ll = 35209 ft. being raised by the power of
steam from the respective depths of 88044 and 105627 ft. be-
low the surface of the sea, whilst there is an uninterrupted
communication between the sea and the volcanic focus. The
difficulty mentioned by Gay-Lussac, that the water would,
under its own pressure, take the gaseous form before reaching
the strata, which are at a white heat ; without being able to raise
the lavas, to cause earthquakes, and to support the volcanic phe-
nomena ; is consequently also set aside, in so far that the water
cannot assume the form of gas under its own pressure before
reaching those depths and their corresponding temperatures. At
depths greater than 88044 or 105627 ft. below the surface of the
sea, if the communication with the sea remained free, a reaction
would take place in the column of water. Perhaps the pheno-
mena mentioned in chap, xi, on Hot and Mineral Sprinj'js, vol.
xxiii. of Ed. New Phil. Journal, and observed by Horner near
the Kur'ile Islands, as well as the powerful stream of hot steam,
observed by Hoffmann near Vidcano^-f beneath the surface of
the sea, probably at the same place where the crater of the cone
formerly thrown up at this spot was situated, proceeds from a
.similar volcanic effervescence. In general the rising of smoke
from the sea during the eruptions of neighbouring volcanos is
by no means an uncommon occurrence. % The reflux and the

* To simplify the calculation, I have supposed the mean temperature of
the surface = 32° F.
t Loco cit. p. 67.
% D. Curbeto (Von Buch loco cit. p. 78) observed a great quantity of smoke

Volcanos and Earthquakes, 41

internal agitation of the sea is also a forerunner of almost all
eruptions, especially of those of Vesuvius.

But if a reaction should take place in the column of water,
yet the rising vapour would soon be so far cooled down as to
become liquid again, without the expansive force of the enor-
mous quantities of vapour formed at the volcanic focus being
thereby perceptibly diminished. In addition to this, the hy-
draulic resistance in the narrow channels, through which the
water is admitted, increases very considerably as its velocity
becomes greater. But the column of water, by which the
aqueous vapour is cut off from communication with the surface,
acquires very great velocity in those narrow channels, from the
enormously increased elastic force of the steam, by which the
resistance may very easily be increased to the exttnt of much
more than 1000 atmospheres. So that, notwithstanding that
the expansive force of steam whose temperature exceeds 1754°
or 1881° F. is greater than the hydrostatic pressure of the
column of confining water, yet this resistance may suffice, in
the manner just mentioned, to raise a column of lava, of even
a greater height than we have above reckoned, to the summit
of the volcano. If we may be allowed to make a comparison
with an analogous phenomenon, it may be remembered that the
touchhole of a camion, or of a bore-hole in a mine, does not
weaken much the action of the powder, although the proportion
of the diameter of the touchhole to that of the mouth of the
cannon is as 1 : 30.* If Perkins's well known observation, j

and flames (?) accompanied with tremendous detonations, rise from the sea
near Lamerote, during tlie volcanic eruption on that island. Fish and pieces
of pumice were seen floating about. Several examples of this sort are
cited farther on.

* But even when the touchhole becomes considerably widened by fre-
quent use, the cannon is still of service, although, indeed, its power is some-
Avhat diminished. Yet the force with which the powder projects the ball
is equal to about 2200 atmospheres, in which the loss occasioned in the ab-
solute expansive force of the powder by the touchhole, &c. is already
allowed for. Muncke in Gehlers Physikal. Worterbuch, new edition, v. 1.
p. 712.

t Quarterly Journ. of Sc. July to Dec. 1827, p. 471, and Annal. de Chim.
et de Phys. xxxvi, p. 435. See also Muncke in Poggendoi-ff''s Ann. vol, xiii,
p. 244, and Buff^in the same, vol. xxv, p. 591.

42 Prof. Bischof oil the Natural History of

that water and steam cannot be forced through narraw open-
ings in the red-hot generator of a steam engine, is apph'cable to
the gigantic generator, which formed the volcanic focus ; this
might be added to the causes already mentioned, which afford
resistance in the channels through which the waters are ad-
mitted.

So long as the communication with the sea remained open,
the volcano could never come to a state of rest, although the
formation, or much more the access of new lava from remote
places, might require a long period before actual volcanic erup-
tions could again take place. Of Vesuvius we know that tlie
periods, when it is entirely free from evolutions of aqueous va-
pour, are not of long duration. On Lancer ate some of the
cones, which were erupted eighty years ago, still continue to emit
steam. The cones of Jondlo emitted boiling hot vapours, and
boiling springs rose in the neighbourhood at the time when
von Humboldt visited them, that is forty-four years after the
last eruption. Burkart, on visiting Jondlo twenty-four years
afterwards, saw scarcely any evolution of watery vapour from
these cones ; but vapour of the temperature of between 113"
and 129" F. was still rising from fissures in the neighbour-
hood of the principal crater.* Very hot vapour continues to
the present day to issue in all directions from the sides of the
rocks on Pantellaria. and yet there seem to have been no erup-
tions on this island since the commencement of the historical
era. *f"

But it is very probable that the channels by which the water
enters become obstructed from time to time. This may be ef-
fected by the lava itself, which is the more likely, as the chan-
nels may perhaps be very narrow. It may, however, also be
caused by the hot steam. Indeed, Monticelli and Covelli ob-
served, during the eruption of Vesuvius in October of 1821,
that the fragments of lava, when no longer possessed of a great
internal heat, remained separate ; but that when they were
themselves very hot, or traversed by the hot vapours, they
united so firmly together, that they could only be separated by

* Aufenthalt and Reisen in Mexico in den Jahren, 1825, bis 1834 vou
Burkart. Stuttgart 1836, t. i. p. 227 and 228.
t Hoffmann, loco cit. p. C9.

Vulcanos and Earthquakes. 48

heavy blows with a hammer on the tenacious surface. * If the
aqueous vapours of ordinary elasticity and temperature are
able to effect this, what effect, it may be asked, may not steam
of such extraordinary elasticity, and of a temperature equal or
even greater than the melting point of lava, exert upon fusible
rocks, solidified masses of lava, &c., which it meets with far
above the volcanic focus in colder regions ? Would not such
steam convert the rock into melted liquid matter ? It is, in-
deed, difficult to conceive a state of which even Papin's diges-
tor can give us but a slight idea.

If the channels become obstructed after a considerable quan-
tity of water has found its way to the volcanic focus, the
aqueous vapour may attain its maximum elasticity, as the focus
will act like a steam-boiler closed on all sides, that is to say, it
will be able, according to the above calculations, to raise a
column of lava of 88747 feet.

The filtration of a large quantity of water, which, although
it becomes gradually heated as it descends, is prevented by its
velocity from assuming the temperature of the strata through
which it passes, must tend to cool the volcanic masses. But it
will be cooled to a far greater extent by the considerable forma-
tion of steam. In this manner a gradual solidification of the
lava will take place not only in the crater, but also in the great
volcanic focus itself,f whereby the termination of the volcanic
eruptions is produced. The contraction of the walls of the
volcanic focus during the reduction of their temperature causes

* Loco cit. p. 10. It may perhaps be allowed here to mention an obser-
vation of my own, though on a somewhat limited scale. I foimd that the
stones by which the Kaisersquelle at Aix l<i Chapelle is closed, and that the ca-
nals of the Scliwerdtbad at Btu'tscheid, whicli consist of black marble, were con-
vei'ted on the inner side into a doughy mass by the continued action of the
steam. But the temperature of this steam is only 133° to 167° F. There
occur innumerable instances of decompositions and alterations which rocks
suffer when exposed to the continued eiFects of heat and acid watery va-
pours. Sec among others Krug von Kidda, p. 274. Burkart, loco cit. t. i.
p. 194.

t Necker, Memoires de la Societe de Physique et d'Histoire Naturello
de Geneve. Geneve, t. ii. part i. p. 155.

Z Observations made on Vesurius and the PeaJc of Teneriffe shew, that the
greater part of the ashes is thrown out last, so that their appearance may bt*
considered as a sign of the approaching termination of the eruption. In pro-

44 Prof. Bischof o?i the Natural Historij of

fissures in the rocks,* by which the waters are admitted in
other places. But in doing so, it may frequently happen that
these fissures do jiot communicate with the channels by which
the water is admitted, and that the volcanic action is conse-
quently for a time suspended, but that on its revival the
slightest shock is sufficient to break through the walls, and
thus to reopen the communication.! This may even be caused
by the expansion of the cooled walls of the focus by the heat
communicated to them from all sides ; in the same manner as a
small crack in a crucible increases when exposed to a red heat.
The more the temperature of the lava is reduced by the
water and the generation of the steam, the longer will be the time
recpiired for the refusion of the solidified lava. In this manner
a long period may elapse, as the lava is so very bad a conduc-
tor of heat.:]: The repose and activity of a volcano are, therefore,
the alternate solidification and liquefaction of the lava, and the
interruption and renewal of the supply of water to the volcanic
focus. II If the store of lava in the volcanic focus should at
first become exhausted by repeated discharges, the volcano is
entirely reduced to a state of rest, or at least until it receives a

portion as the elasticity of the vapours diminish, the substances will be
tlirown to a less distance, so that the black rapilli, which are the first eject-
ed after the lava has ceased to flow, will be cast farther than the white
ones. Von Humboldt's Keise, t. i. p. 245.

* It is well known tliat considerable fissures are formed in lava during
its cooling, especially when it is on the surface of the earth. The streams
of lava in the coimtry surrounding the Laachcr-Sec, offer many instances of
this kind. Hamilton also mentions great fissures in the lava-streams of
VesiiTius. Gilbert's Annal. t. vi. p. 23. See also Necker, loco cit.

t "We may here notice the well-known phenomenon, that among the
ejected masses from a volcano, pieces of rock occur, which neither belong to
the substances composing the edge of the volcanic cone, nor to those found in
the vicinity, and therefore must be derived from masses concealed very deep
under the volcano. Vesuvius particularly, furnishes remarkable instances
of this kind. Such ejected masses, however, are now found much more
rarely than formerly on this or other volcanos, from which it seems to
follow, that the channels of the ejections have been by degrees widened.

Ij: Monticelli and Covelli, loco cit. p. 15 and 39.

11 Experiments hitherto made shew, that long spaces of time are requi-
site to produce the strongest effects, viz. the elevation of lava to the great-
est height. Von Humboldt (Reise, &c. t. i. p. 261.) calls our attention to the
circumstance, that long intervals of quiescence seem to characterize the

Volcanos and Earthquakes. 45

fresh supply of lava from a distance. If the afflux of water be
not interrupted, the exhalations of vapour may still continue,
of which we have already mentioned several instances.

We may next consider how lava may be elevated from the
depth of a volcanic focus. The hypothesis, which ascribes
volcanic phenomena to the central heat, supposes that melted
matters exist at a certain depth. In adopting this opinion, we
need not assume that lava is produced by the melting of solid
rocks, but on the contrary, that melted matters have existed
since the creation of the world. f In the annexed diagram

very high volcanos. The smallest of all, Stromholif is nearly always in ac-
tivity. The eruptions of Vesuvws are less frequent, although they arc still
more so than those of Etna and the Peak of Teneriffe. During the quiescence
of the latter, from 1706 to 1798, sixteen eruptions of the former took place.
From the colossal summits of the Andes, Cotopaxi and Tuvgurahia, an eiiip-
tion is observed scarcely once in a century. We may venture to state,
that the frequency of the eruptions of active volcanos is inversely as their
height and mass. After these general remarks, we may mention the cir-
cumstance that large lava streams, namely, such as issue from Etna and
VesuvinSj never flow from the crater itself, and that the quantity of the
melted matters is commonly inversely as the height of the fissures from
which the lava issues. But a lateral eruption of these two last-mentioned
volcanos always terminates by an emission of the ashes from the crater,
that is, from the summit of the mountain itself. This phenomenon has not
been seen on tlie Peak of Teneriffe these last hundred years. The crater was
most inactive during the eruption in the year 1708. Its basis did not sink,
v.hilst the greater or less depth of the crater of Vesurim, according to the
acute remark of Yon Buch, is an almost infallible sign of an impending
fresh eruption. Von Humboldt, p. 268. All this shews that the conditions
requisite for producing the greatest eifect, viz. for producing the highest
degree of the increased elasticity of the M'atery vapoure, are not always
present.

+ On this supposition, we assume that no basalt has been produced by
the repeated melting of any known rock. Leonhard's Basalt Gebildc,
&c. Stuttgart, 1832, t. i. p. 263. /

46 Prof. Bischof o?i the Natural History of

AB represents the boundary between the solid crust of the
earth and the melted matters in the interior of the earth ; CD
represents a wide rent, exhibiting a communication from the
surface to the melted matters ; EF, GH, IK, LM, &c. are
narrow rents conducting water from the sea or subterranean

o

collection of water to the heated interior ;* and F, H, K, M
may be caverns in the solid crust, formed during the consoli-
dation of the originally fluid matters of a former period. Un-
der these circumstances it may easily be conceived, that water
penetrating into the above mentioned rents and caverns is con-
verted into steam, which, by pressing on the melted matters,
causes them to rise through the rent CD. If the lower opening
in the wide rent at D be on the same level as the whole bound-
ary between the solid rocks and the melted matters, small
quantities of these only will be raised upwards, for the surface
of the melted matters will soon sink below the opening of the
rent at 1), and steam will rise. Thus the elevation of a column
of lava to a considerable height by a column of steam will take
place. But if the lower opening of the rent CD descends more
or less below the surface of the melted matters, considerable
quantities of these will rise into it before this surface sinks be-
low the opening. The same may take place if between the
opening of the rent CD and the other rents (those down which
water flows from the surface), ridges of solid rock reach down-
wards from the solid crust into the fluid mass.

Such ridges may be viewed as occasioned by gradual solidi-
fication of the fluid mass from above downwards, for it is well
known that melted matters, if they crystallise by cooling, exhi-
bit on their under surface considerable inequalities ; and the
consolidation of the melted matters in the interior of the earth
is assuredly produced by crystallisation.

There is another circumstance which may cause a continuation
of the rent CD into the melted matters. After the rising of
the lava and steam in this rent, the walls of it are cooled by
the formation of steam, and by the atmospheric air having a
ready access to the empty channel. Therefore these walls

* Water will naturally also penetrate into the wide rent, but, inasmuch
as it is not able to fill up the rent; it cannot confine the steam generated be-
neath, and the latter will therefore escape.

Volcanos and Earthquakes. ¥1

may gradually increase by the solidifying of the melted mat-
ters; nay, the rent may be entirely solidified and obstructed,
so that it can only now be re-opened by the force of steam pre-
vious to a new eruption taking place. If even immense quan-
tities of lava are ejected by the steam, yet the level of the melt-
ed matters in the interior may be but slightly changed, for
in the same manner, as all seas on the surface of the earth
communicate together, so the melted matter in the interior does
the same. However, more or less time may elapse, before the
melted matter which has sunk at one place in consequence of
ejection, can regain its former level by the afflux of other melt-
ed matters from a distance. Therefore the repose and ac-
tivity of a volcano, besides depending on the interruption
and renewal of the supply of water to the volcanic focus, may
also proceed from the alternate obstruction and re-opening of
the lava channel by the melted matters. In, the latter case, in
the state of rest, exhalations of steam will take place, inasmuch
as water penetrates continually to the volcanic focus.

But if the afflux of water be interrupted by an obstruction
of the water-ducts, and if none of the above-mentioned causes
be capable of restoring the communication ; or if. during the
repose of the volcano, the lava-ducts become so obstructed by
consolidation, that the steam cannot force its way through
them, a volcano may reach a state of perpetual repose. Such
causes may have effected the extinction of the volcanic activity
of the numerous extinct volcanos distributed throughout the
globe. If this took place at a former period, when the thick-
ness of the crust of the earth was still increasing considerably,
in consequence of the gradually cooling of the earth, and as
this process is still going on, there is no probability that such
extinct volcanos will at any time become again active.

If volcanos, for instance Etna, are considerably elevated
above the surface of the earth, it commonly happens that the
walls of the lava-channels cannot resist the pressure of the
melted matter in their interior. In this case rents are formed
from which the lava issues. Such rents are always seen in the
direction of the axis of the volcanic cone,* and their extent is

* Von Buck's Beobachtungen, &c. t. ii. p. 137.

48 Prof. Bischof on Natural History of

often very considerable. A rent of this description produced by
one of the most violent eruptions of Etna, viz. that of the 11th
May 1669, was 2^ German miles in length, and occupied al-
most one-third of its height. Scrope* saw distinct traces of it
near Nicolosi so late as the year 1819. Even the rent formed
during the eruption in 1794 on the declivity of Vesuvius, to-
wards Torre del Greco, was, according to Von Buch, 3000
feet in length, and according to Breislak 237 feet in breadth
at its upper edge.

Other volcanos afford instances of the formation of rents
and hills. Thus during the most violent eruption of Scaptar
Jdkul on Iceland in 1783, a rent e^'ght Enghsh miles in length
was formed in a plain at the foot of the mountain. Three
craters, from which immense quantities of lava flowed out, rose
in the direction of the rent, and afterwards a fourth appeared
below the sea in the same direction, and at a distance of thirty
miles, the eruption of which formed an island, which afterwards
disappeared again t. Similar phenomena took place in the
same year in the island of Java. And Von Buchf informs
us, that in the island of Lancerote, during the eruption in the
year 1730, a rent was formed above two German miles in length,
on which about twelve conical hills rose, whose summits were
from 600 to 800 feet in height.

In like manner basaltic cones, (also porphyritic and granitic
hills) are often seen, which are situated in a line, and of which
two or more are connected by rents, which are filled up by
basalt. Remarkable phenomena of this kind are seen near
Murol in Ativergne. |i

It seems surprising that the same kinds of lava are not alwavs
ejected from volcanos. V^on Buch § distinguished on Vesuvius
alone eighteen distinct principal kinds of lava ; and old and new
lavas of Etna also differ in their characters. The lavas of neigh-
bouring volcanos are often very different from each other. In
like manner, unstratified rocks of very different natures are

* Considerations, p. 158. t Ibid, p. 154.

:{: Leouhard's Taschenbucli, 1824, t. ii. p. 439.

II Leonliard's Basalt Gebilde, t. i. p. 408.

§ Bcobachtungen, &c. t. ii. p. 174.

Volcanos and Earthquakes. 49

often met with close to each other.* The Sieheitgebirge, near
Bonn, offer remarkable instances of this kind. There, trachytes,
trachyte tuffs, basalts, and basalt tuffs, are met with close
to each other. Basalt dykes traverse the trachyte and the
trachyte tuffs, and volcanic scoriae occur on the Roderberg^
opposite to the Siehengebirge, on the left bank of the Rhi7ii\
However different all these rocks are, yet they seem to lead
to the conclusion that their ori<^in has been from the very
same materials ; for, notwithstanding this difference in their na-
ture, it would be easy to form in the S'lebengebirge a gradation
from a white trachyte to a compact black basalt.-f* On the other
hand, there is every reason to suppose that the nature of the
melted matters in the interior is different in different places.
If, therefore, after the ejections of melted matters existing in a
particular spot, new eruptions will take place only when such
matters flow from remote places towards this spot, we can hence
easily conceive how different lavas may be ejected at different
times. In the Siebengebirge, as well as in other places where
unstratificd or volcanic rocks occur, many instances are exhibit-
ed, which indicate that these rocks are of very different ages.i"

If the activity of a volcano ceases, but the channels by which
the waters enter remain open, the volcanic action may be re-
placed by hot springs. § In this case it is easy to conceive
that the meteoric waters, continually sinking into the hot inte-
rior, would there assume the surrounding high temperature, and
rise again to the surface with a temperature, diminished propor-
tionally to the decrease of pressure, eicher through the former

* The lavas of Vesntiusy of the Solfatanty of Ischia, and of Etna, are quite*
different in their nature.

t See Leonard Horner on the Geology of the Environs of IJonn, in the
'I'ransactions of the Geolo<,'icul Society, vol. iv., 2d Scr. p. 43«. Von Buch
states tliat in several places in the neighbourhood of Clermont and I'u^ da
Dome, a transition from granite into trachyte may be traced, and thvs to
have the gradation extended from granite to basalt.

t L. llorner, 1. c. p. 407.

§ Von Buch, loco cit. p. 65. A remark of some interest in tracing the
counoction of hot springs witli volcanic phenomena is made by Burkart>
loco cit. vol. i. p. 31G, viz. that the boiling hot springs in the valley of Pot^
are situated on a line, running from east to west, parallel to the general liii»
of volcanos in Mejclco.

VOL. XXVI. NO. LI. JANUAUV 1839. D

50 Prof. Bischof on the Natural Htsiory of

lava-channels, or other fissures more recently opened.* But if
at that depth, the hydrostatic pressure be greater than the elas-
tic force, which the water has there acquired, no steam will he
generated in the whole course of the spring ; but, in the con-
trary case, from the lowest point up to the point where the elas-
tic force becomes greater than the hydrostatic pressure, the wa-
ter will escape in the form of a vapour. However high the
temperature of the water may be at the lowest point of its course,
■whether in the liquid or in the gaseous state, yet, when it
reaches the surface, it cannot exceed the boiling point. Tlic
reason of springs but seldom attaining even this maximum may
be either the loss of heat communicated to the superior strata of
the earth, or that they meet with streams of gas, (carbonic acid,
or sulphureted hydrogen), which, even if possessed of a very
high temperature, will cause a depression of their temperature, as
is proved by experiments cited in Chap. II. of Memoir on Springs,
p. S36, vol. XX. Ed. Phil. Journ.t The production of hot
springs, according to the last species of volcanic action, may,
however, be thus imagined; that the water which descends to
the volcanic focus is there converted into steam, which, rising
through fissures into higher regions, meets with atmospheric wa-
ters which it warms, and wifth them returns to the surface.J
The course of hot springs produced in this manner can, there-
fore, occur only at inconsiderable depths below the surface.
Lastly, it may happen that the lava last raised did not escape
from the crater or its lateral openings, but became soHd on it<

* Von Humboldt is also of opinion, Reise, &c. t. i. p. 187 and 188, that
the vapour which rises from the " Narices del Pico" as they are called, and
from the rents in the crater of Teneriffe, is nothing but atmospherical water
which has penetrated by infiltration.

+ According to M. Arago, the hottest spring in Europe unconnected witli
modern volcanic action is tliat of Chaudesaigues in Awcergne, whose temperii-
ture he quotes at 176° Fahr. Annuaire du Bureau des Longitudes, 18 3u.
The next hottest to this seems to be 2'huez, in the Pyrenees, whose tempera-
ture is, according to Professor Forbes, 171.°5 Fahr. Phil. Trans, t. ii. p. 603,
for 182C. Forbes believes, p. 61 0, the baths of Nero, near Naples, the hottest
spring on the Continent of Europe, which is connected with modem volca-
jiic action, the temperature being 182.°2 Fahr.

:}: Perhaps the numerous hot mineral springs which rise at the foot of the
still smoking mass of rocks on Pantellaria, as well as the numerous hot sid-
phureous springs in the vicinity of Sciacca, in Sicili/, have a similar origin.
Jloffman, 1. c.

Volcanos and Earthquakes. 51

way onwards, and thus stopped up the channels. If, in this
case, water should descend through rents into this btill ex-
tremely hot lava, hot springs would also thus be produced, sup-
posing a communication between these and other rents which lead
to the surface at a lower level ; but these springs will decrease in
temperature by degrees as the lava gradually cools, till they
reach that degree which naturally belongs to the place where
the lava is situated. However, we have already proved by ex-
periments formerly mentioned, and calculations founded upon
them, that, if such masses of heated lava be of considerable ex-
tent, a very long period may elapse before the decrease in the
temperature of the springs will be even perceptible.* On the
other hand, there are examples of a very rapid decrease in the
temperature of hot springs in the neighbourhood of volcanos
recently become extinct. Thus, the temperature of the hot
springs on Jorullo decreased 40°5 F. in 24 years, between
the visits of Von Humboldt and JBurkart.f The tempera-
ture of the mixture of gases which issues from the rents in the
Pass of Quindiu, near the Moral, in the Quebrada del Azvfral^
decreased from 1801 to 1827, according to the observations of
Von Humboldt and Boussingault, from 11<8° to 66°4.J If,.
instead of this gas, a mineral spring had flowed at this place, it
would, doubtless, have suffered a similar diminution of tempe-
rature. Boussingault mentions, on the other hand, that, in a
a period of twenty-three years, the temperature of the hot
springs of Mariana and Las Trincheras rose several degrees.
According to the observations of Hamilton, Delia Torre,
Abbe Soulavie, Von Humboldt, and Forbes, the hot spring
named La Fisciarella, which rises near Naples, from the exte-
rior of the cone of the Solfatara, is subject to extraordinary al-
ternations in its temperature, from 101° F. to 199°4 F.§
But even in very short periods striking differences are some-

* Die vulkanischen Mineralquellen, &.c. p. 150. — I have calculated,
that, under the circumstances there mentioned, a mass of melting basalt,
equal in size to one-third of the Donnersberg^ near MiUeschaUy in Bohemia,
Avould be sufficient to have heated all the water which has issued from
the whole number of springs at Caaishad since the time of Adam.

t Burkart, loco cit. t. i. p. 22C.

+ Poggendorft's AnnaL t, xviii. p. 858.

§ Forbes, loco cit. p. Gil.

52 Prof. Bischof on the Natural History of

limes found. Thus Forster* asserts, that in the neighbourhood
of Tanna, a volcano on one of the Neio Hebrides, the hot springs
vary several degrees in temperature from one day to the other.
There is not, perhaps, a more striking example of the inti-
mate connexion existing between volcanic phenomena and hot
springs than in Iceland. As the volcanic eruptions are there
confined to the district of the trachyte- formation, so also are the
principal mineral springs only found in this formation ;t from
which it seems natural to infer, that it is one and the same pro-
cess acting in both cases, but in a different manner.J

The hot springs in this volcanic island confirm Krug Von
Nidda'*s system of classing thermal springs — namely, 1. such
as are constantly bubbling and boiling up — permanent ther-
mals ; 2. those in which this ebullition only takes ^lace at par-
iicular periods, and which are perfectly tranquil during the re-
maining time — intermitting thermals ; and, i], those whose sur-
face is always undisturbed, and in whiclt no bubbling or boiling
ever takes place. The springs of the first class always have a
temperature at the surface equal to that of boiling water under
the usual atmospheric pressure. Those of the second class only
reach the boiling point during their temporary ebullition, and
lose considerably in temperature during their period of rest.
The springs of the third class never reach the boiling point of
water.

The most famous of the intermittent springs is the Great
Geyser. At the time when Krug Von Nidda visited it, it pre-
sented two different kinds of eruption. The smaller ones were
repeated regularly every two hours ; and the water was thrown
only from fifteen to twenty feet high. The greater ones suc-
ceeded each other at intervals of from twenty-four to thirty
hours ; in these cases, the masses of steam ascended to the
clouds, and the water spouted to a height of ninety feet. For
two hours after one of the smaller eruptions, during which
time there were no traces of action, and only thin clouds of

* Journ. de Phys. 1779, p. 434.

t All the hot springs of Mexico also rise out of trachyte and dolerite rocks'
Burkart, p. 363.

X Krug Von Nidda on the mineial springs of Ireland, p. 272, in Karston";
Archiv. t. ix. p. 247, and in Jameson's Phil. Journal, vol. xxii. p. 90 and 220 j

Volcanos and Earthquakes, 53

steam were formed at the surface, the temperature of the water
was 194}° F., which was reduced still lower by the evaporation.
After a dull rumbling noise within, the water suddenly began
to boil up again, the basin was filled till it flowed over, immense
bubbles x)f steam burst from the funnel-shaped opening, and
})rojected the water to a height of about twenty feet. Imme-
diately after the eruption, when tranquillity was completely
restored, the water was at the boiling point, but its tempera-
ture soon fell below that degree.

The Strokr, the eruptions of which almost exceed in gran-
(leur those of the Great Geyser^ has this peculiarity, that it is
at the same time a permanent and an intermittent thermal
spring. It shews itself to be permanent by its incessant ebul-
lition, and intermittent by the tremendous eruptions which
seem to be repeated at intervals of from two to three days.

No doubt can be entertained respecting the nature of the
.igent by which the waters of the Geyser^ tlie StroJcr, and other
less considerable springs, are thrown to such an immense
height. It is, as in volcanos, a gaseous body, principally
aqueous vapour. We may, therefore, very fairly agree with
Krug Von Nidda, and consider volcanos in the same light as
intermittent springs, with this diflerence only, that instead of
Mater they throw out melted matters.

He takes it for granted that these hot springs derive their
temperature from aqueous vapours rising from below. When
these vapours are able to rise freely in a continued column,
the water at the different depths must have a constant tempera-
ture, equal to that at which water would boil under the pres-
sure existing at the respective depths. Hence the constant
ebullition of the permanent springs, and their boiling heat. If,
on the other hand, the vapours be prevented, by the compli-
cated windings of its channels, from rising to the surface ; if,
for example, they be arrested in caverns, the temperature in
the upper layers of water must necessarily sink, because a large
(juantity of it is lost by evaporation at the surface, which cannot
be replaced from below. And any circulation of the layers of
water at different temperatures, by reason of their unequal spe-
lific gravities, seems to be very much interrupted by the nar-
rowness and sinuosity of the passage. The intermitting springs

54 Prof. Bischof on the Natural History of

of Iceland are probably caused by the existence of caverns, in
which the vapour is retained by the pressure of the column of
water in the channel which leads to the surface. Here this
vapour collects, and presses the water in the cavern downwards
until its elastic force becomes sufficiently great to effect a pass-
age through the colunm of water which confines it. The vio-
lent escape of the vapour causes the thunder-like subterranean
sound, and the trembling of the earth, Avhich ])recede each
eruption. The vapours do not appear at the surface till they
have heated the water to their own temperature. When so
much vapour has escaped that the expansive force of that
which remains has become less than the pressure of the con-
fining column of water, tranquillity is restored, and this lasts
until such a quantity of vapour is again collected as to produce
a fresh eruption. The spouting of the spring is, therefore, re-
peated at intervals, depending upon the capacity of the cavern,
the height of the column of water, and the heat generated be-
low.*

The two distinct classes of eruption in the Geyser^ which we
have already mentioned, seem to be attributable to two diffe-
rent cavities. A smaller cavity fills quicker, and, therefore,
empties itself more frequently ; a larger one fills slower, empties
itself seldomer, but with greater violence. But the playing of
the Geyser, the Strokr, and some others, is subject to very great

■■' The eiiiptions of the Geyser and the Strokr, as observed by Krug Von
Nidda, agree exactly with his explanation of the action of the intermitting-
springs of Iceland. A thick column of smoke suddenly burst out of the
latter, and rose to the clouds. The water was hurled with tei'riiic violence
out of the crater, and mixed like a fine mist with the rest of the column to
a considerable height. From time to time thin streams of wafer were seen
shooting in a vertical or oblique direction through the column of smoke,
sometimes rising to a height of a hundred feet and upwards. Large stones,
which had been previously thrown in, were flung almost out of sight, and
many so perfectly vertically that they fell down again into the crater, and
were again throAvn up into the air, like a juggler's ball. The whole of the
water was thrown out at the beginning ; and afterwards, the column which
ascended from the opening, was composed only of steam, which rushed out
■with a whistling and hissing noise, and rose with incredible velocity into
the clouds. It continued for three quarters of an hour in this state of a(!fti-
vity. It then again became (j liescent, except that the water, deep in tlu'
tube, continued, as usual, to boil violently.

Volcanos and Earthquakes, SSf,

variation s. Channels may become stopped by the incrusting
property of the water. During the frequent shocks which ac-
company the greater eruptions, some cavities may fall in, and
be choked up, and new ones formed. The greatest changes,
liowever,, are caused by the earthquakes, which from time to
time visit the island. Thus, during the earthquake of 1789,
the most important spring in the country, next to the Geyser,
disappeared, and at present only steam is evolved from its mouth,
while the Sirokr, which before this was but an inconsiderable
sjoring, increased to such an extent, that it is now considered
to rival the Geyser in importance. It may be observed, that
the eruptions of the Stroikr have no connection whatever with
those of the Great Geyser. During the long eruption of the
former the latter remained quite quiet, and vice versa. In
general, each of these numerous hot springs, which are here
crowded together in a very small compass, seems to be totally
independent of each other. This might also be inferred from
the striking difference in their levels.

It seems probable from the situation of the celebrated hot-
springs of Iceland (of which more than fifty may be counted in
a space of a few acres, at the foot of a rock about 300 feet high,
which leans against a chain of higher rocks) ; from the numerous
fissures in these rocks, which are composed of alternate layers
of tuffas, of slag-streams, and slag-conglomerates, as well as
from the fact, that tlie springs are confined exclusively to the
lower region, which extends along the foot of the hill, whilst
on its sides and summit are found only gaseous exhalations
(aqueous vapour and sulphureted hydrogen gas) ; that these
springs are supplied from the meteoric waters of the neighbour-
ing hills, and that, being originally cold, they are indebted for
their high temperature solely to the hot vapours which they
.ceive from below. The hot-springs in Iceland seem, therc-
xore, to be produced in the manner described at page 50.

Lastly, If the permanent obstruction of the lava and the water
channels has taken place, of course no hot-springs can exist, or
at least they can only flow during the cooling of the lava last
t jected and solidified. This seems to have been the case in the
volcanic district of the Siehengehirge, the Laacher See, and the
Eifel, as in these places no hot-springs, with the exception of

56 Prof. Bischof on the Natural History of

the baths of Bertrich, are to be met with ; although in the two
latter districts, the number of thermal springs, whose tem-
perature exceeds that of the soil at the most by a few degrees,
are enormous, and considerable exhalations of carbonic gas
give evidence of former volcanic action. It may, however,
be conjectured, with some probability, that in the vicinity of
the Laacher See and in the Eifel, springs may have existed,
whose duration depended on the cooling of the masses of lava.
Similar circunistances seem to have occurred in Auvergne and
Vivarais, although the hot-springs, which are not uncommon
in those countries, show that many of the former volcanic chan-
nels are still unobstructed.

The examination of deposits obviously formed from springs*
which existed at a former time, may often present an indication
of their temperature. Thus, on the volcanic tongue of land
called the Sneefield-Syssel^ in Iceland, we find none of the hot
mineral springs which are so numerous in other parts of the
island, and which are distinguished by their holding silica in
solution, and exhaling sulphureted hydrogen gas. But, in
former times they existed here, for in many places we find sili-
ceous incrustations in the form of tuflfas and sinters. One cold
spring, which is now flowing, has certainly taken the place of
a hot siliceous spring, for its present deposits are only calca-
reous, and quite distinct from the older incrustations.* The
circumstance that arragonite is deposited from hot-springs,
calcareous spar, on the other hand, from cold ones, gives us
also an indication of this kind. Since G. Roset pointed out
that the former is only deposited from a hot solution of car- j
bonate of lime, the occurrence of arragonite in any deposit
leads us to infer with certainty that these deposits owe their ^
origin to a hot spring. If, on the contrary, we find calcareous
spar in any deposit, we may infer with equal certainty that it
was produced by a cold spring. J

* K. V. NiJda, loco cit. p. 282. f Poggendorff's Annal. t. xl. ^. 353.

4: The following remark may not be" entirely superfluous, viz. accord-
ing to G. Hose, arragonite is formed in a higher temperature only in ,
the moist way, hut calcareous spar is formed in the dry way. Thus car-
bonate of lime crystallizes from a state of fusion under strong pressure
only in the form of calcareous spar. Arragonite exposed to a slight red
Jieat is easily converted into calcareous spar.

Volcanos and Earthquakes. 57

If the melted nucleus of the earth be the common seat of the
volcanic activity of the whole earth, subterranean communica-
tions subsist between all volcanos. The existence of such com-
munications cannot be doubted. Immediately after the earth-
quake which overthrew Caraca^^ there followed the great erup-
tion of the volcano of ^S*^ Vincent^ and the earth no longer trem-
bled at Venezuela. When the dense, black column of smoke,
which, in the year of 1797, had issued for several months from
the volcano near that city, disappeared, the cities of Riobamba^
Hambato, and Tacunga^ 280 English miles distant, were at
the same hour destroyed by a violent shock.* Other instances
of this kind will be mentioned afterwards.

Andrea Lorenzo Curbeto's description of the great vol-
canic eruption in the island of Lancerote, for which we are in-
debted to Von Buch,-f- also shews how for six years, from 1730
to 1736, the gaseous fluids in the interior found new vents in
all directions, sometimes here and sometimes there, and yet
were not capable of preserving a single one permanently open.
Sometimes two or three openings were formed at once with a tre-
mendous crash accompanied with flames, (?) which alarmed the
whole island. At one time three apertures united suddenly
into one very high cone ; lava flowed out below and reached the
sea. If, says that acute geologist, the unhappy Laiiccrote had,
like Teneriffe, possessed a volcano, perhaps not one of those
numerous cones would have been thrown up, and probably not
a single village would have been destroyed.^ He thinks it
highly probable that this eruption took place entirely from one
great rent.

'^ Von Humboldt Reise, t. 1. p. 498. t Loco cit.

X Von Buch supposes that only the gaseous matters, but not solid sub-
stances, viz. lavas, slags, rapilli, and ashes, proceed from the focus of the
volcanic plienomena. He observes that these masses always shew them-
xelves to be of a nature corresponding to the roclvs out of which they are
ejected.

We must not forget that Von Buch avjis at that time still attached to
Davy's hypothesis, which ascribes volcanic phenomena to the combustion
«)f the metals of the alkalies and earths, and which does not require us to
ssupposc the origin of volcanic action to lie at any great depth. It is in-

58 Prof. Bischof on the Natural History of

During the violent eruption in the low country of Skaptar
J ok id in Iceland^ in 1733, which suddenly brought up the most
enormous masses to the surface, the lava burst forth at three
different points, more than two geographical miles distant from
one another, and spread over a surface in the plain,* which is
supposed to equal in extent sixty geographical square miles.
This mass is so considerable as to surpass in magnitude that of
Mont Blanch Under almost the whole of Iceland there is a
volcanic furnace, which communicates by many apertures with
the surface. The masses of melted matter, therefore, seek an
outlet at various points, and many places are mentioned, at
which the lava has only been ejected once within historical
times. The volcanic phenomena are not confined to the island
alone,, they also break through in the neighbouring sea. In
January 1783, such an eruption took place in the sea, eight
geographical miles from Cape Re'ikianes, several islands were
raised, and great quantities of pumice and light slags were
floated on the coast. In June the whole island was shaken by
earthquakes. The submarine eruption discontinued, and at a
distance of fifty geographical miles the grand eruption of

deed, very diiFerent, according to the hypothesis which Ave are endeavour-
ing to defend. In this the seat of the volcanic actions is supposed to be
identical with the place where the elastic forces producing them act. The
connection between the lavas, and the slags, rapilli, and ashes resulting
frouL them, and the rocks at the surface, would only then shew that the
same material which composed the rocks, raised at a former period, and
now spread over the surface, has also sers-ed for the production of the- more
recent volcanic formations. But it still remains to be taken into considera-
tion, that aqueous vapour, generated in the lowest point of the volcanic
focus, possessing its maximum of elasticity, and heated to the melting point
of lava, or above it, is capable, as we have already said, without the assist-
ance of any other power, of converting fusible roeks into a state of hydro-
igneous fusion.

* See Om Tordbranden paa Island i Aaret 17^3, ved Student Soemimd
Mugnussen. Kort beskrivelse over den eye Vulkans, Ildsprudning i Yester
Skiiptcfells Syssel paa Island i Aaret 1783 of INIagnus Stephen sen. Kioben-
Ijavn 1785. Sir G. Makenzie's Travels in Iceland. Ganlieb's Island, 1810,
p. 64. Th. Gliemann geogr. Beschi'eibung von Island, 1824, p. 107. Pen-
nant le Nord de Globe, t. i.

t Berghaus Abnanac for 1838, p. 75.

Volcanos and Earthquakes. 5f^

Skaptar Jdkul comrtiewced. On the 13th June 1 830, a simi-
lar submarine eruption was repeated.*

The immense masses of lava ejected from a single volcano,
and the enormous extent in which volcanic actions are felt at the
same time, scarcely leave room to doubt that every active vol-
cano is in immediate communication with the whole melted
matter in the interior. In this manner alone can it be conceived,
how, for instance, the masses ejected at different times from
Vesuvius vastly exceed the whole bulk of the mountain,-f* while
tlie latter seems upon the whole to undergo no diminution,
for the falling in of its cone at one period appears to be ba-
lanced by the accumulation of ashes at another.

If a rent reaching from the surface to the melted matters in
the interior be of great length, but not open throughout its
whole extent, the first eruption will take place where there is
the least resistance.

If this channel become obstructed, the volcanic fire will seek
another vent.. I Violent concussions may open new fissures §
and close old ones, by which frequent changes may be produced
in the channels of the lava and water. Fissures obstructed by
lava are closed so firmly as to be incapable of being re-opened ;
new ones, therefore, are formed. Thus it is, at least, if a vol-
cano produce eruptions from its sides. If it happen that a wide
and lasting vent be formed, all partial workings in the neigh-
bourhood will cease. A similar combination, although on a
somewhat limited scale, is presented by groups of mineral
springs, especially of hot springs. In such groups new channels

* Joimi. de Gc^ologie, t. i.

t This was remarked even by the ancients ; and Seneca, Letter 7&, after
stating the difficulty, solves it by remarking-, that the fire of the volcano,
*' in ipso monte non alimentum liabet, sed viam." — Daiibeny on Volcanos,
p. 155.

:J: Thus the interior of the crater of the Peak of Tenerife shews it to be u
volcano, which for thousands of years has thrown out fire only from its
sides. V. Humboldt, Reise, t. i. p. 105.

§ According to the inhabitants of JVew Audahmay the soil in various dis-
tricts in their pro\4nce has become more and more arid, in consequence of
the frequent earthquakes with which they are visited from time to time.
V. Humboldt, Reise, t. ii. p. 21.

60 Prof. Bischof on the Natural History of

are seen to open, new springs to rise, and old ones to close. The
only difference is, that, as these changes are not accompanied
with any violent action, as is the case with volcanos, they re-
quire a greater length of time for their accomplishment.

We have, in the preceding inquiries, as yet only supposed
the admission of water from the sea. But this does not seem
always to be the case, even in volcanos situated near the sea.
According to Hamilton,* the water of the springs and wells of
Torre del Greco diminished so much a few days before the
great eruption of Vesuvius, on the 15th June 1794, that the
eorn-mills at the principal spring were nearly stopped, and it
was daily necessary to lengthen the ropes in the wells, in order
to reach the water. Some wells dried quite up^ and on the
morning of the IStli June, at Resiria, a subterranean rumbling
noise was heard after a heavy rain. Monticelli and Covelli f
relate that, before the great eruption of this volcano in 1822,
at the beginning of January, the springs at Resina, St Jorio,
and particularly in the places in the immediate vicinity of
Vesuvius, diminished perceptibly. J Monticelli observed simi-
lar phenomena before the eruption in 1813, and he thinks
that, in general, they are a sure sign of one. It is hardly to be
doubted that rents were opened by the earthquakes, through
which the water descended to greater depths, accumulating,
perhaps, in great caverns, and from thence found its way to
the source of the volcanic action.

We find considerable accumulations of water in all moun-
tains traversed by numerous fissures. We will only now men-

* Phil. Trans, for 1795, p. 73.

t Loco cit. pp. 12 and C3. See also Monticelli, in Leonard's Taschcn-
buch fiir die gesammte Mineralogie, vol. xiv. p. 87.

J The same was observed twenty-three days before the earthquake in
■Ciilahria; and. also in the Peak of Teneriffe, in 1706. Yon Humboldt, Relat.
Hist. t. i. p. 393. In Iceland^ this phenomenon was observed before the ter-
rible eruption of Slcajytar Jokul, in 1784. In general, in volcanic districts,
the porous and much fissured rocks swallow up the rain-water, and carry it
down to very great depths. Von Humboldt gives this as the cause of the
extreme aridity Avhich reigns in most of the Canary Islands, notwithstand-
ing the height of the mountains, and the mass of clouds which travellers
always see collected over this Archipelago. Reise, t. i. p. 173.

Volcanos and Earthquakes. 61

tion the western declivity of the Teutoburger Wald, in which
such considerable rivers have their source; the Jura moun-
tains ; and the Gcrmni.* The volcanic inundations, of which
Von Humboldt gives such extraordinary cxamples,t are an
additional evidence of the existence of such great subterranean
accumulations of water, in the vicinity of volcanos. Lastly,
we have, further, examples of volcanos coming into action
after violent storms of rain ; for instance, the Mer-Api, in
Java.X In the Andes of Quito, the Indians imagine they have
observed, that the quantity of percolating snow-water increases
the activity of volcanos.§ Can it, then, any longer be doubted,
that the proximity of the ccean is by no means a necessary con-
dition in the production of volcanic phenomena ? But all that
has been said respecting the channels by which the sea-water is
admitted to the volcanic focus, holds equally good with respect
to those admitting springs or rain-water ; only with this dif-
ference, that, in the more lofty volcanos of Aviei'ica, the vol-
canic focus may be imagined much higher, and yet columns of
water of considerable pressure will not be wanting, provided
those accumulations of water be situated at a great height in
the mountains.

The same power by which masses of lava are forced up,
sometimes so as to reach the surface and flow over it, or in
other cases becoming solidified in their channels, will also raise
whole mountains. These elevations may take place through

* Von Humboldt (Reise, t. iii. p. 229), mentions several rivers which lose
themselves in the gneiss rocks. When these gneiss mountains were up-
raised, considerable caverns may have been formed, which were afterwards
filled with water.

t Annal. de Chim. et de Phys. t. xxvii, p. 128. This circumstance, how-
over, must bo considered, that the strong heat over the active volcano di-
lates the atmosphere, and produces a rising stream of air. The consetpience
of that is an influx of air from all sides. But this air is aecomi)anied with
moisture, which, rising with it, is condensed in tlie higher regions of the
atmosphere, and falls down in showers. Therefore, an active volcano affords
not only water, which immediately issues from its interior, but it also de-
prives all the environs of water. Du Carta sur les iuondat. Volcaniques.
Journ. de Physique, t. xx. p. 103.

It: Memoir of the Conquest of Java. London, 1815, p. 40.

§ Von Humboldt's Reise, t. i. p. 263.

62 Prof. Bischof on the Natural History of

rents of more or less considerable width ; and partly form
dykes, or mountains of some magnitude ; or raise up or break
through the upper strata of the earth. Thus Von Buch* in-
forms us that on the island of Lancerote^ during an eruption
in 1730, a rent was formed above two German miles in length,
on which about twelve conical hills had risen, whose summits were
from 600 to 800 feet in height. In like manner basaltic cones
(also even porphvritic and granitic hills) are situated in a line,
and of which two or more are connected by rents, which are
filled up by basalt. Remarkable phenomena of this kind are
seen near Murol in Auvergiie.

We have abundance of proofs of the rising of masses of melt-
ed or at least semifluid matter, J out of the interior of the earth,
in the filling up of dykes with compact crystalline rocks, in all
of which, as in the rocks of undoubted volcanic origin, felspar
forms a necessary and principal ingredient.§ We find these
rocks in contact with all the stratified and superficial forma-
tions, even with those which are going on at the present day.
But similar masses, which have evidently flowed in streams
from craters, are also found in positions which shew that they
must have risen from the interior of the earth, after the forma-
tion of the stratified rocks, and found their way into fissures,
which in many cases do not reach the surface. Thus, granite,
syenite, trachyte, the porphyries, the greenstone, and so on, up
to the basalts, form dykes in the stratified rocks as well as in one
another. They also not unfrequently appear in beds between

* Leonard'^ Tasclienbuch, 1824, Abtli. ii, p. 439.

t Leonhard die Basalt Gebilde, t. i. p. 408.

Z Cones of basalt, trachyte, and pliondlite, whose inclination is often very
considerable, cannot have risen in such a thin liquid state, as that in whicli
lava issues from volcanos ; for, according to the observations of Elie de
Beaumont already mentioned, lava streams having an inclination of only G°
cannot form a continuous mass. See on this subject Leonhard, loco cit. t. i.
p. 417, &c.

§ Felspar may certainly be considered as a characteristic sign of an igne-
ous origin in rocks, as this mineral is never found in rocks, in the forma-
tion of which the action of volcanic power can be proved to have been
wholly excluded.

Volcanos and Earthquakes. 63

the strata of the Neptunian rocks. Granites have been forced
up to the surface at the most widely different periods ; we find
them most commonly in clay-slate, and in the greywacke for-
mation, in gneiss and in mica-slate, and they are sometimes con-
nected with other more considerable masses of granite. Even
after the formation of the oolitic and chalk groups, they have
been ejected; but there are no granitic dykes described as
intersecting these rocks. The stratified rocks are usually al-
tered in the immediate vicinity of masses or dykes of granite ;
and their stratification becomes indistinct and confused. The
porphyries, like the granites, exist as independent formations ;
but these are not so frequent or so extensive, and are more fre-
quently in contact with more recent stratified formations than
the granites. The trap rocks traverse all the stratified rocks
from the gneiss and greywacke group, at least to the oolites in-
clusively. The basalts are found in all formations, from the
transition and secondary rocks to the bgnite inclusively, nay,
in the nexyest formations.*

In general, some alteration in the adjacent rock and some
new mineral production s,t are found where such masses have
been forced up, and large and small fragments of the rock are
not uncommonly found firmly imbedded in the latter. We may
here, by way of example, mention the conversion of compact
limestones into marble, exactly as Hall changed limestones by
heating them in close vessels or under pressure ; and again, the
disappearance of the black colour and the bitumen in the coal-
sandstone.j

* Leonliard's Basalt Gebilde t. ii. p. 6, &c.

+ The adjacent rock, heated by the melting mass, might, by their both
cooling very slowly together, give rise to the production of crystalline sub-
stances (as hornblende, felspar, mica, by the contact of gi-anite with clay-
slate). But the rock would probably also take up substances from the melting
mass (alkalies) which Avould serve as a flux.

Z The combustion of beds of brown coal seems also to have been effect-
ed by igneous fluid masses which had risen from the interior. Thus the
remains of such combustions always occur in Bohemia^ according to Dr
lleuss (Noggerath Ausflug nach Bohmen. Bonn. 1838, p. 171), in the neigh-
bourhood.of basalts, and these plienomena are so enormous, that they can-
not be considered as caused by accidental combustions.

64 Prof. Bischof on the Natural History of

The conglomerates which frequently surround these volcanic
masses, and which are not confined to the basalts and trachytes,
but are also found accompanying the greenstones, porphyries,
and granites, Von Buch considers to be produced by the fric-
tion of the rising matter against the rock ; and their existence
is a further proof of the pyrogenetic origin of these masses.

Other phenomena lead us also to infer that crystalline rocks
have risen in a melted state. If, for instance, such rocks are
separated by rents, crystals are often found in them, broken
through the middle, and both pieces are imbedded in the sepa-
rated rocks. Thus, my friend Prof. Noggerath has observed,
that many of the larger crystals of glassy felspar in the trachyte
of the Drachenjels are broken through in this manner, and
that the one piece is displaced several lines from the other.
He observed the same phenomenon more frequently in the
porphyritic granite near Gopjersgriin in the Fichtelgebirge*
The olivine in the basalt of Burzet in Vivarais presents the
same appearance, according to Scrope,+ and the separated por-
tions of crystals exactly correspond. Faujas observed among
the basalts of the bridge of Bridoit adjacent columns, with in-
cluded fragments of granite broken through, in consequence of
the formation of the columns. All these phenomena prove
that these crystalline rocks must have been still soft, after the
imbedded crystals had arrived at the stage of perfect solidifica-
tion, and that the breaking of the crystals is a consequence
of cooling.

The occurrence of arragonite in the fissures and cavities
of crystalline rocks, basalt, for instance, seems also, according
to the above-mentioned experiments of G. Rose, to prove, that
these rocks were at least still hot, when cold solutions of car-
bonate of lime penetrated into the fissures.

Lastly, instances of the formation of dykes of volcanic mat-
ter at the present day, offer a further proof, if further proof be
necessary, of their igneous origin, and the accounts given of the

* Noggerath loco cit. p. 71- See also Goldfuss and Bischof, Physika-
lisch-statistische Beschreibung des Fichtelbirges, t. ii. p. 114.

+ Consider, p. 1 36.

Volcano^ and Earthquakes. G5

recent eruptions at Ponohohoa in Owhyliee^^ establish the pos-
sibility of eruptions through rents.

If alterations in the adjacent rocks, or other phenomena aU
ready mentioned, are not observed, we may infer that the ele-
vations havQ taken place in a solid state. Notwithstanding this
solidity, the highly elastic and exceedingly hot vapours may
certainly cause considerable chemical alterations in the elevated
masses, as well as in the adjacent rocks.

It is impossible to determine any regular order of succession
in the elevation of the pyrogenetic rocks. They occur in every
period of the stratified formations. Older ones have very com-
monly received those of more recent date into their fissures.
There scarcely exists a single unstratified rock which is not
somewhere to be found filling up dykes in granite. Basalt-
tlykes traverse many unstratified rocks, such as trachyte, con-
glomerate, and others. In Iceland^ tufa is found alternating
with slaggy lava ; and dykes of a porous trachytic rock traverse
the tufa of Stromholi and Vidcanello in the Lipari Islands^
&c.t

Masses of melted r^atter will break through the bottom of
the sea more easily, 1 -cause resistance is there the least consi-
derable. To this may be ascribed the frequent elevation of
islands from the bottom of the sea, not only in historical times,
but also at the present day, and under the eyes of observers, in
whom the utmost confidence may be placed. The most extra-
ordinary and instructive island in this respect is Santorin, be-
cause it unites the whole history of volcanic islands and islands
of elevation. A more beautiful, regular, and perfect crater of
elevation is not to be found, than in the space which is almost
entirely surrounded, by the inner circle of Santorin (wliich en-
compasses more than one-half of it), and by its continuation
as exhibited in the islands of Therasia and Aspronisi.i Here
it is probable that the clay-slate was broken through and up-

* Pog<rendorff's Auual. t. ix. p. 141.

t De la Beclie, Ilandbucli der Geoguosie Von v. Decben. Berlin, 1832.
Absclmitt xi.

t Von Biicb iu Poggondorff's Annal. v. x. p. 172. See the drawing iu
his splendid atlas, and the sketch in these annal. v, xxiv. p. 1.

VOL. XXVI. NO. LI. JANUAKY 1839- ^

66 Prof. Bischof on the Natural History of

raised. These islands, therefore, form an inseparable whole,
and cannot liave been raised one after another. On the other
hand, history and tradition inform us, that nature has never
ceased in its endeavours to create a volcano in the centre
of this crater of elevation. 184 years before the birth of
Christ, the Island of Hiera (now called Palaia Kameni),^ was
formed, and since that, as it seems, many other rocks have
been raised in its centre. In 1427, this island was increased.
In 1573, the Little Kameni was thrown up, exactly in the
centre of the basin, accompanied with an ejection of steam
and pumice; and between 1707 and 1709, was raised the Nezo
Kameni, which still continues to send forth sulphurous vapours. t
Lastly, in the present moment another new island seems to
be about to appear to the east of Kameni^ about 900 feet from
the coast of Santorin, according to the report of a naval of-
ficer of Santorin^X {Nauplia, 4th December 1834). The in-
habitants of the island assert, that thirty years ago this bank
lay at the depth of 90 feet ; in 1820, it was only 60 feet below
the surface ; and at present the sea is only 20 feet deep over
it. According to later accounts given in the public journals,
this bank continues to rise so rapidly, that if it meet with no
interruption in its progress, it will, by the year 1840, be able
to lay claim to the denomination of an island. In the year
1713, it is said an island arose among the small islands near
Venice^ accompanied with flames, smoke, and the most vehement
shocks. This phenomenon, which continued four weeks, drove
away the inhabitants from the adjacent islands. After about
two years a similar occurrence was repeated, and a second
island was thrown up under the same circumstances. These
two islands are now, as the neighbouring ones, inhabited and
cultivated.il

* Von HofF, Geschichte der natiirlichen Veranderungen der Erdober-
fldche, t. ii. p. 137. For an account of some crater-shaped islands, see Pog-
gendorfF's Annal. v. xxiv. p. 101.

t See the account of Fatlier Bourignon in Raspe's specimen, &c. de novis
e mare natis insulis 1763, p. 48.

:;: Allgenieines Organ fur Handel und Gewerbe &c. No. 23. 1835; and
Jameson's Phil. Journal, vol. xxi. p. 175.

11 Justi's Geschichte des Erdkorpers, p. 135.

Volcatws and Earthquakes. 67

From Leop. Von Buch's instructive exposition of the nature
of volcanic phenomena,* which, together wiih the careful works of
Von Hoff, contain a critical compilation of all cases yet known of
the production of new mountains and islands by volcanic action,
we will borrow only the following examples of recent date. The
first I shall mention is the island of Sabrina, near St Miguel,
in the Azores, which is celebrated for the many islands that
have attempted to rise in its vicinity, and which made its
appearance on the 13th or 15th June 1811 ; it began to dis-
appear in October, and towards the end of February 1812,
steam was only occasionally seen to rise out of the sea at the
spot where the island was formerly seen.*|* Secondly, The
rising of a new island near Unalaschka, in May 1796, which
not only remained, but, up to 1806, had increased in cir-
cumference, as well as the peak in height. It required six
hours to row round it, and rather more than five hours to
ascend in a direct line from the shore to the summit of the
peak.J The creation of both these islands was preceded by
violent earthquakes, and columns of smoke, which ascended
from the sea, whilst stones were thrown to a great distance. Of
Sabrina this surprising circumstance is related — that the stones,
on leaving the sea, were black, but suddenly became red hot
when they emerged from the columns of smoke. Tillard found
on this island the skeleton of a shark so calcined, that the bones
fell to powder on lifting it up. Of the other island it is only
said, that during the night fire rose, which was sometimes so
bright, that all objects were distinctly visible in Unalaschka, at
a distance of twenty leagues. Smoke continued to rise for four
years.

Phenomena of this kind have taken place still more recently
among the Molucca Isles, as we are informed by Prof. Rein-

'' PoggendorfF's Ann. v. x. p. 1 and following, p. 169, 345, and 514 and
foUoAving.

t See also V. Humboldt's Keise, t. i. p. 254, and t. iii. p. 6. It is worthy
of remark, that the small island of 1720 has reached exactly the same height
as Sabrina attained in 1811.

X It was, consequently, more than 1000 feet high. Unfortimately the
depth of the sea at that place is not given. But it certainly offers an ex-
ample of one of the greatest elevations of the present day.

e2

68 Prof. BischoF on the Natural History of

wardt.* Near the active volcano of Gonung Api, in the group
of the Banda Islands^ a considerable mass of black rock rose up
in a bay, out of the sea, without any noise. When Reinwardt
visited this extraordinary spot in 1821, he found it still very hot,
and the newly raised mass sent forth boiling hot vapours. A
precisely similar occurrence took place on the Coast of Ternate.
On Lancerote also, on the 31st August 1824, after several days
of violent earthquakes, accompanied with a subterranean thunder
like noise, a new volcano burst forth with a terrific crash, emit-
ting streams of fire, so that the whole island was illuminated,
and throwing up so many red hot stones and fragments of
rock, as to form a mountain within twenty-four hours.t

The last occurrence we shall mention, and which is still fresh
in our memory, namely, the volcanic island which appeared
in July 1830, in the Mediterranean, between the south-west
coast of Sicily and Pantellaria, shews, that these phenomena
may take place in two different ways. New islands may be
formed in the sea either by the elevation of solid rock, by violently
breaking and raising up the original strata, or merely by the
heaping up of the loose masses which are ejected.]; This event
was of the latter description, and in its ephemeral existence ex-
actly resembles the above-mentioned case in the Azores. Under
which of these forms such volcanic productions appear, may de-
pend on the nature and thickness of the rocks to be broken through,
on the depth of the sea at the place of the eruption, and the
strength of the volcanic force. However, the visible part of this
island may, perhaps, as is the case with many others, only have
been the summit of a peak situated in the centre of a crater of
elevation, wliich remained buried in the sea, similar to the cones
of many land volcanos, which, if they had been situated in the
sea, would have been unable long to withstand the action of the
waves, as is the case with most of these islands. Hoffman,^
who approached very near to this island, shortly after its ap-
pearance, saw quite plainly, that it was nothing else than the

* De incendiis montium igui ardentiuni insulse Javsc, &c. disputatio geo-
logica. Aiictore van der Boon Mesch. Lugdimi, Batav. 1826.
f Annal. de Cliim. et de Pliys, t. xxvii. p. 382.

X See, on the contrary, Von Humboldt in his Beise, t. i. p. 254, note.
§ Poggendorft's Ann. t. xxiv. p. 75.

Volcanos and Earthquakes. ^^

edge of a crater, the walls of which were gradually raised above
the surface of the water by the materials ejected from it. From
this crater vapours rose uninterruptedly with great violence, yet
without noise, which were succeeded by the ejection of slags,
sand, and ashes. The appearance of this island was also pre-
ceded by a noise resembling thunder, and by the elevation of a
mass of black coloured water to a height of eighty-two feet,
columns of smoke rising at the same time to a great height.
The accounts leave us in uncertainty respecting one of the most
important circumstances — whether fire rose out of the crater or
not. However, Hoffman and his companions are inclined to
the more probable opinion, that this volcano vomited no fire,
and that what some observers took for flames, was only the^-
rilli in the smoke.* Lightning, caused by the electricity ex-
cited by the rapid evaporation, was observed there, as it is
during the eruptions of Vesuvius and other igneous mountains.
At the end of December 1830, this island, which was 2100 feet
in circumference, and the highest point of which rose 210 feet
above the sea, shared the fate of Sahrina, and disappeared.
From the bottom of the sea it had risen between TOO and 900
feet; and from what depth below, may be conjectured from the
calculations previously given.

Thus, then, the rising of islands out of the sea is a well au-
thenticated fact, and if we should for a moment be left in
doubt concerning the cause of this phenomenon, by the appear-
ance of steam in the presence of the sea-water, yet the evolu-
tion of aqueous vapour from volcanic islands, enclosed on all
sides by solid rock, seems to dispel such doubts.

Examples of elevations on land in historical times are much,
more rare. Of these v*e are only acquainted with the elevation
of Monte Nuovo near Puzzuoli in 1528, which rose 400 feet in
about three days ; that of Monte Rosso near Caiania in Sicily,
in 1669, which rose to a height of 820 feet in about four weeks,
and that of JoruUo, which rose to a height of 1 480 feet above
the plain, in one day, on the 29th September 1759 +

* Witliout exactly wishing to generalize, tliis circumstance is yet sufii-
cient to render us distrustful in judging of descriptious of siniilar pheno-
mena in which flames are so often mentioned.

t Von Humboldt Nouv^spngiie, v. ii. p. 290. See Burkart loco cit.
vol. i. p. 22G.

70 Prof. Bischof on the Natural History of

These are also formed, like the volcanic islands, in two dif-
ferent ways. The Monte Nuovo was formed by the accumu-
lation of the loose masses ejected from the volcano, whilst
mountains of basalt, trachyte, phonolite, &c. which are so abun-
dantly scattered over the surface of the earth, have been formed
by the upraising of solid rocks.*

Vesuvius, or rather its cone, seems also to present an example
of an elevation in the historic area. Its formation perhaps does
not go farther back than the period of the famous eruption of 79
after the Christian area, in which Herculaneiim and Pompeii were
destroyed ; for ancient writers never speak of the mountain as
consisting of two peaks, which they probably would have done,
if the Monte Somma had stood, as at present, distinct from the
cone of Vesuvius.^ It is also remarked that the distance men-
tioned in ancient writers, as intervening between the foot of
Vesuvius and the towns of Pompeii and Stabiae, appears to
have been greater than exists at present, unless we measure it
from the foot of Monte Somma, so that this affords an addi-
tional probability, that the latter mountain was then viewed as
a part of the former, and that no separation between them had
at that time occurred. We may also be sure from the semicir-
<iular figure which the southern escarpment of the Monte Som-
ma presents towards Vesuvius, that it constituted a portion of
the walls of the original crater; and Visconti, it is said, has
proved by actual measurements, that the centre of the circle,
of which it is a segment, coincides as nearly as possible with
that of the present crater. There seems, therefore, little room
to doubt, that the old mouth of the volcano occupied the spot
now known by the name of the Attrio del Cavallo, but that it
was greatly more extensive than this hollow, as it compre-
hended likewise the space now covered by the cone, which was
thrown up afterwards in consequence of the renewal of the vol-
canic action that had been suspended during so many ages.

* The late investigations of Buch, Dufrenoy, and Elie Beaumont, shew
that the Monte Nuovo is a crater of elevation, therefore not entirely or
chiefly composed of loose massos of ejected rocks. — Edit.

+ Daubeny, a Description of Active and Extinct Volcanos, &c. p. 144.
See also Von Buch in PoggendoriF's Ann. t. xsaj^vii. p. 173.

Volcafios and Earthquakes. 71

This view likewise tends, as it seems, to reconcile the accounts
which ancient writers have given of the structure of the moun-
tain, antecedently to the period before mentioned.*

As for the mode of action of the vapours, it is indifferent
whether they have to contend with loose and unconnected, or
with melting masses, only that the former are propelled into
tlic air like cannon balls,-|- and falling into a parabolic curve,
accumulate and produce a mountain, whilst the latter remain
at the height to which they are borne up by the elastic fluids.

In elevations of the latter description, the vapour cannot
escape through the uplifted mass. This mass is supported by
the elastic force of the vapour, cools gradually, and then re-
mains, as it were, wedged in between the strata it has broken
through. But according to Von Buch^sj: observations on Palma
and Gran Canaria, it may happen, that the vapour bursts
forth from the centre of the mass it has raised, and thus ex-
poses its interior. Such a crater would thus be the effect of
the elevation of the island, for which reason he gives it the
name of crater of elevation (Erhebungs Krater), to distinguish
it from the craters of eruption, by which true volcanos open a
communication with the atmosphere.

Further, this philosopher has pointed out,|| that volcanic
cones cannot be generated by the building up of streams of lava.

'•■ See the Historical Notices given by Daubeny, loco cit. p. 1 45 and fol-
lowing.

t V. Humb. (Reise v. i. p. 226) calculates from the time the stones thrown
out during the lateral eruption of the Peak of Tenerijf'e, on the 9th June 1708,
took in falling (which according to Colofjan was from twelve to fifteen se-
conds, reckoning from the moment they reached their greatest height), that
they were projected to a height of more than 3000 feet. In some similar
observations made by Von Humboldt during the eniptions of Vesutlm in
1805, he satisfied himself that such observations are capable of a great de-
gree of exactitude. Similar calculations made by other observers, give still
greater heights. The maximum height of such projections was observed
at Cotopaxl by La Condamine (Voyage ji I'Equateur), Ho saw proi)elled
laterally, a block of about 1000 square feet, to a distance of nearly I4 geo-
graphical miles.

X Abhandlungen der Berliner Acad, loco cit. p. 58.

II Poggcndoi-ii''s Anual. t. xxxvii. p. 170, &c.

72 Prof. Bischof on the Natural Historij of ^

He infers this from observations made by Elie de Beaumont,
and which have been already alluded to. This philosopher mea-
sured the mean inclination of about thirty lava-streams of Etna,
and of a great many of Vesuvius, and found that a stream
having an inclination of 6°, or even more, forms no continuous
mass. Such a stream inclines too mucli to be able to attain
more than a thickness of a few feet. When its inclination is
only 3° or less, the mass may be spread, and accumulated to
a considerable height*

Lastly, we have to notice the upraisings which are the conse-
quences of earthquakes, and often extend to large islands and
whole tracts of country. Elevations of small compass, accom-
panied by partial depression, which is no doubt merely a con-
sequence of the elevations, were observed before,f and duringf
the famous earthquake of Lisbon. Small elevations also took
place during that in Calabria §. The commissioners who were
employed to make observations of the earthquakes in the county
of Pignerol, relate, that the very day (2d April 1808), when
one of the most violent shocks was felt, the masting engine at
Toulon was elevated more than an inch.|| This observation is
worthy of note, as it shews that many effects of earthquakes
may often take place at great distances from their seat, which,
owing to their minuteness, may escape observation, unless ca-
sually discovered. For accounts of elevations of a more con-
siderable kind in equatorial countries we are indebted to Hum-
boldt. The elevations in the island of Lancerote,^ and those
on the coast of Ciimana'^''^ are of this kind.

The most remarkable instance of the elevation of great tracts
of country of late years, is that which took place in Chili, on
the 19th November 1822. For the account of this important
phenomenon we are indebted to Mrs Maria Graham, a well in-

* Vide Memoir of Elie de Beaumont, in vol. xx. p. 376, &c. Edin. New
Phil. Journ. ; and Description Geologique de la France, t. iv.
t Palassou Mt^m. pour servir k ITIistoire Nat. des Pyren. p. 260.
X Pliilos, Trans, t. xlix. p. 417. § Jour, de Phys. Ixii. 1806. p. 264.

II Idem, t. Ixvii. 1808. p. 308. ^I Relat. Hist. t. i. p. 188.

** Ibid. t. ii. p. 279.

Volcanos and Earthquakes. 73

formed observer.* After violent earthquakes, which were fell
through an extent of country 1400 English miles in length, and
during which it appeared as if the soil was suddenly raised and
immediately sunk again, or as if the earth had an undulating
motion from north to south, accompanied with a noise like the
rushing of steam, the whole coast for an extent of about 100
English miles actually rose between three and four feet within
twenty-four hours.t In all the small valleys the earth in the
gardens was disturbed, and sand and water rose in quantities
through the cracks. The granite rocks near the coast, which
are traversed by small parallel dykes, shewed many narrow
rents parallel to the old ones in some instances. The former
were traced one mile and a half inland. The phenomena which
most forcibly arrested the attention of Mrs Graham, were e\u
dent marks of this coast having been raised in a similar manner
by earthquakes in former times, and indeed to a height of fifty
feet above the sea level.

The latter phenomena are so much the more important the more
frequently they occur. We can, therefore, have no difficulty
in admitting most earthquakes to have been the causes of such
elevations. Many coasts, as is well known, bear evident marks
of having been raised in former times. Thus Vetchj obser-
ved on the coast of the island of Jura in Scotland six to seven
terraces one above another, the lowest at the level of the sea, the
highest about forty feet above it, all covered on their horizontal
surfaces with pebbles like those which the sea still throws
up. Mr Smith of Jordanhill has also pointed out, that in
a former time an elevation of the west coast of Scotland has

* Geol. Transact, v. i., Sec. Series, part ii. p. 413. Mr Greenough felt
disposed to call in question the observations of Mrs Graham, but she has
defended her statements very creditably, and has been supported by Mr
Meyen, Berghaus Annal. der Erdkunde, t. xi. p. 129.

+ Fr. Place also confirms this account of the extent of the elevation, in
.lourn. of Sc. No. xxxiii. p. 3G. According to the reports in the Ann. dc
('him. et de Pliys. t. xxvii. p. 350, two volcanos, in the neighbourhood of
FaWtm, presented a sudden eruption with a loud noise, and illuminated th«
whole country for some seconds, but they soon subsided again. At tho
Kume time a slight shock was felt in that town.

:}: Geological Trans. Sec. Series, v. i. part ii. p. 416.

74 Prof. Bischof on the Natural History of

taken place.* Peron noticed a similar phenomenon on the
coasts of some islands in the neighbourhood of Van DiemeTi's
Land. Many other instances of this kind occur, which present
traces of elevations, some of them perfectly incontestable,*f-
others very probable.J In conformity with this are also the
assertions of the inhabitants of Otaheite,§ and those of the Mo-
luccas,\\ that their islands still continue to rise.

The latest earthquakes, which, in the month of February
1835, destroyed a great part of Chili, {Conception, and many
other towns), offer also evident proofs of elevations occasioned
through their agency. Some days after this devastation the sea
did not rise to its ordinary level, the difference amounting to
four or five feet in height. This difference decreased gradually;
in the middle of April it was still two feet. The fact that the
island of Santa Maria has risen nine feet, proves the actual
elevation of the country. Near TuhuJ, south-east of Santa
Maria, the country has risen six feet, and the island of Mocha
seems to have risen about two feet.1I

The gradual elevation of Scandinavia and Fiftland is pecu-
liarly interesting. More than a century ago Celsius called at-
tention to this phenomenon, and endeavoured to account for it
by a gradual sinking of the level of the Baltic. Playfair,** how-
ever, remarked, as early as the year 1802, that an elevation of
the land may be assigned as the cause of this phenomenon with
more probability than a sinking of the water. This supposition,
he thinks, accords with Hutton's theory, according to which the
continents have been actually raised by subterraneous powers,
and are even now supported by them in their place. Lastly,
Von Buch,tt without having seen Playfair^s work, gave his

* Phil. Mag. V. X. p. 136 ; Jameson's Phil, Journal, vol. xxv. p. 378 ; and
Mem. Wernerian Soc. vol. viii. part. i. in the press.

+ Dolomieu Orylctol. Bemerk. Uber Calabrien. Frankf. u. Mainz 1780,
p. 167.

J Brochi in Biblioteca Italiana 1821. Sept. Breislak Reisen in Cara-
panien, t. ii. p. 115.
[ § Correspondence Astronomique, v. x. p. 266.
\ I! PoggendorfF's Ann. t, ii. p. 444, according to Prof. Reinwardt.
•fl Nautical Magazine, No. 49 and 51. March and June 1836.
** Illustrations of the Huttonian theory,
ft Reise durch Norwegen und Lappland, t. ii. p. 389.

Volcanos and Earthquakes. 75

opinion, " that the whole country, from Frederkhshall'm Swedtih
to Abo in Finland, is in the act of rising slowly and insensibly.''
The rising of the Gulf of Bothnia amounts, according to the
observations communicated by Hallstrom, from B. 71 to 4. 61
feet ; on an average 4. 26 feet during a century,* Beds of sea-
shells, found sometimes 200 feet above the present level of the
sea, as, for instance, on the sea-coast and on the islands of Ud-
devalloy as also on all the sea-coasts of the south of Norway, and
which sea-shells consist of such kinds as arc still found living at
these places in the sea, prove how much the level of the Baltic
has changed even during the time that the present testaceae
have inhabited it.-I* But the rising seems to be very unequal
at various places. In the north it is more considerable than
in the south. On the eastern coast of the Danish islands of
M'oen and Seeland, Lyellj; found no indication of a recent
elevation of land. The first place along the whole coast of
the Baltic, where an elevation is said to have taken place, is
the town of Calmar. Beyond the Swedish coast, on the coast
of Finland, the inhabitants are perfectly convinced either that
the water sinks or the land rises. This remarkable phenomenon
has excited a general interest amono^ the Swedish naturalists,
and caused continual exact observations of the marks inscribed
on the shores of the Gulph of Bothnia. Thus Nilson§ thinks
he has found convincing proofs that the most southern part of
Sweden is sinking, whilst the remaining part is rising. He has
also endeavoured to give probability to the supposition, that the
sinking took place, and still takes place, not suddenly, but gra-
dually. Forchhammer|| likewise alluded to similar phenomena,
in order to prove that elevations in Scandinavia take place not
only in different proportions, but that a depression is also going
on. He infers from his observations, that the level of the coast
of Denmark has varied in a different proportion from that of the
Swedish coast, which he ascribes to the feeble earthquakes that

* Bruncrona u. Hallstrom in Poggend. Ann. t. ii. p. 308.
t Berzelius Jahresbericht, 182G, p. 292.
+ PoggendorfF's Ann. t. xxxviii. p. 64.

§ Berzelius Jahresbericht, No. 18, p. 386, and Poggendorflf*s Ann. t xliL
p. 472.

II Phil. Mag. ser. iii. v. ii. p. 309, and Poggend. Ann. t. xlii. p. 476.

76 Prof. Bischof on the Natural History of

have been felt so often in Szveden, but never" \\r Denmark. He
estimates, according to rough calculations, the elevation of the is-
land Bor7ihoIm to amount to one foot in the course of a century.
If elevations of countries., in which volcanic actions are felt, and
which are agitated by violent earthquakes, be produced, as is
very probable, by the same causes as these phenomena, yet it is
difficult to imagine these causes to operate in elevating countries
where no such phenomena occur, or where, at least, they take
place but rarely or to a small extent. The latter is the case
in the Scandinavian Peninsula. That region has no active
volcanos, no hot springs — even thermal springs bearing a tem-
perature of but a few degrees higher than the mean temperature
of the place, are considered as rarities ; whilst, in other coun-
tries, they are of very frequent occurrence. All this proves that
the crust of the earth in this country must be very soHd, and
traversed by comparatively few rents or fissures.

Berzelius assigns as the cause of this rising of the Swedish
coast, the gradual cooling of the earth; and says: " Its diameter,
in this manner, decreases, and the consolidated crust leaves either
empty spaces between itself and the fluid mass, or sinks down-
wards. Being, however, of so large an extent that foldings
and bendings must occur, portions must rise up on one side and
sink on the other. This supposition seems to be supported by
the sinking of the western coast of Greenla7id, and of an island
situated in the Gulf of Youghall, a phenomenon which has
been recently pointed out by Ehe de Beaumont and Pingel.
Kloden also has recently given much probability to the sup-
position of a sinking of the Dalmatian coast,*

We shall endeavour to shew in our next section what effect
might be expected on the surface of the earth, if its solid crust
should still continue to increase in thickness towards the inte-
rior by gradual consolidation of the fluid centre. Besides I
think that a sinking^ the outer crust can scarcely be supposed
to occur, but that it is much more probable that caverns should
be formed at the moment, when the fluid mass becomes sohd.
Al least the latter effect was seen in fusing two basalt balls
two feet in diameter, in which many larger and smaller cavities

* Poggendorff's Ann., t. xliii. p. 361.

Volcanos and Earthquakes, 77

were found. I shall allude to these phenomena in another
section.

If we take into consideration all that has been already said
on ejections and elevations ( soultvemens ) we shall be induced
to adopt the following inferences. Masses of our earth, still in
a fluid state, may be raised through and above its solid crust.
Th^ rising of the lava in the craters of volcanos is a satisfactory
proof of this circumstance. Solid rocky masses, strongly
heated, may be pushed upwards during violent convulsions
and elevations of the original rocky covering, or be thrown up
in the form of loose masses, more or less heated. The not un-
frequent rising of small islands from the bottom of the sea, and
the elevations ( souUvemens ) actually observed to take place in
the continents, are evidences of these operations. All these
phenomena are effects of forces, which develope their whole in-
tensity in a very short time, often in a few moments. But
large islands, and even whole countries may, in a very short
time, be raised several feet, as was shewn in the cases of Chili
and Santa Maria, On the other hand, Scandinavia presents
us with an instance of an elevation which, compared with the
preceding, takes place with extraordinary slowness.

Besides all these elevations which have been actually ob-
served, other appearances occur, which lead us to infer that
elevations have taken place previous to the existence of any
record. These are the elevations of old volcanic masses, as ba-
salt, trachyte, &c. their penetration into fissures, and the eleva-
tion of whole systems of mountains. In regard to the first, the
conclusion may, as has been already shewn, be considered as
well founded as it is generally possible to be, when drawn from
phenomena which have taken place before any records were in
existence. The similarity between these phenomena, and those
which have taken, and still take place, before our eyes, render
it extremely probable that they were produced by forces which
were in operation for a very short period only. Changes in
tlie contiguous rocks, and the imbedmcnt of fragments of
them in the volcanic rocks, render it also equally probable that
these masses were raised in a fluid, or at least softened state,
and either rose above the surface of the earth in the form
of conical mountains, or remained adhering in rents of the

78 Prof. Bischof on the Natural History of

rocks. These phenomena, then, belong entirely to the same
class as the elevations of lava in volcanic craters. When, on
the other hand, no changes are perceived in the contiguous
rocks, when these have been simply broken through and up-
raised, when the broken masses consist of acute-angled fragments
of all dimensions heaped one upon another, then wc cannot as-
sume that the elevations took place in a fluid or softened state.
AVere elevations of this kind the work of a short space of
time, or did they proceed slowly ? In vain do we look around
us for some clew to the solution of this question. From phy-
sical gi'ounds we are led to the following conclusions. If fused
rock come in contact with water in the interior of the earth,
the watery vapour disengaged will operate, with the whole ex-
pansive force which it can acquire from the heat of the rock, in
a short time ; provided that the continued formation of vapour
be not limited by want of water. It is the same process as that
which takes place in the glass-blower's blow-pipe when he forms
large globes. If, then, water acts on fused masses in a confined
space, we have the conditions requisite for producing a rapid ele-
vation, and therefore, as a general rule, we may regard elevations
of fused masses and rapid elevations as co-ordinate phenomena.
If, on the other hand, we imagine a solid rock deep under the
surface, whose temperature is far below a red heat, then its
elevation can only take place when a considerable source of
heat exists under the rock, which gives rise to the formation of
vapour. But the more the heat of the vapour exceeds that of
the rock, which is to be raised and supported by it, the more
will it become condensed, and thus a great part of the effect is
lost. If the condensed vapour return to the source of heat, it
will again assume the form of vapour, and thus a constant cir-
culation will ensue. It is actually a process of heating by
steam. If the solid rock be a very bad conductor of heat, then
that surface which is in contact with the vapour, may gradually
acquire its temperature, and the vapour thus attain its maxi-
mum of operative force. It naturally depends on the weight
of the solid mass, whether the vapour can effect its elevation,
and by what elasticity. Although we must suppose that the
elastic force of the vapour progressively increases, in proportion
as the temperature of the surface of rock in contact with it rises ;

Volcanos and Earthquakes, 79

yet, on the other hand, we must consider, that when the vapour,
which had not yet attained its maximum of expansive force, has
effected an elevation, then, a regressive effect, as regards dura-
tion of time, will ensue, because, by the elevation, the space
which confined the vapour has become enlarged. Secondly, if
the conducting power of the solid mass be greater than we have
just assumed it to be, then the heat, which is communicated to
the surface of contact by condensation of vapour, is as quickly
diffused above, as it can be conveyed from the vapour below,
and if the latter produce a continued elevation, the effect must
inevitably be regressive. We can therefore conceive it possible,
under the conditions stated, that the same force, viz. vapour of
water, which, when in contact with a fused mass, developes its
whole intensity in a short time, can produce only a gradual
effect, when in contact with solid masses whose temperature is
far below that of the vapour. We thus see the possibility of
fused masses being raised by vapour in a short time, while solid
masses may be raised very slowly by the same agent, and that
the latter elevation may go on in a regressive ratio. Lastly,
it is even possible that a gradual elevation of a solid mass may
continue, although the elevating effect of the vapour has long
ceased. For instance., if the subterraneous heating by steam
continue, and if the heat, communicated to the surface of con-
tact by condensation of the vapour, be diffused above more
slowly than it is conveyed below, then it is clear that the solid
mass supported by the vapour, will gradually be expanded.

These remarks have shewn that the operations of vapour, as
an elevating force, may be very various as regards the relations
of time and space, and that its effects depend not only on its
own temperature, but also on that of the masses it has to ele-
vate, on their relative conducting power, and lastly, on the ca-
pacity of the space within which its operations take place.

We can therefore understand how the slow elevation of Scoiv-
dinavia may be a result of the operation of watery vapour, ta-
king place in a diminishing ratio, and how therefore this phe-
nomenon stands in close connexion with the original elevation
of that country, which is principally composed of masses of ig-
neous origin. We shall pass over the consideration of the
question, whether this original elevation took place in a fluid or

80 Prof. Bischof o?t Volcanos.

solid state, that [is, whether in earlier times these masses rose
suddenly and continued to rise more and more slowly as they
gradually cooled, or wliether this gradually decreasing ratio
has always existed. We may, however, be allowed the remark,
that the slow elevation which still continues when the operation
of the vapour, as an elevating power, has long ceased, may be
regarded, according to what has been stated above, as the re-
sult of an expansion produced by the caloric disengaged from
the vapour during its condensation. For example, let us as-
sume that the solid crust of the earth in Scandinavia was
139,840 feet thick, that the expansion of this crust by heat
takes place in the same ratio as in earthen ware ; then, an ave-
rage increase of heat of 2°9 R. during the space of 100 years,
would be sufficient to effect an expansion of 4. 26 feet in a stra-
tum of the above-mentioned thickness. And this is the average
ratio of the rising of that country.

Be the cause of the elevation of Scandinavia what it may,
this circumstance is remarkable, that in the southern part of
Sweden^ where the country, according to Nilson's statement,
sinks, secondary formations, viz. chalk, occur in great abund-
ance, while in the north of Sweden, as well as in Finland, the
gneiss-granite formation predominates. We must not, however,
attach too much importance to the connexion which appears to
exist between the elevation of the northern part of Szveden and
the prevalence of the latter formation, as Nilson* says, the
chalk also lies on gneiss, and less frequently on greywacke. It
is nevertheless remarkable that the granite island of Bor?ihoIm,
which is situated opposite to the sinking coast of Schonen, is
still in the act of rising, according to the observations of Forch*
hammer above alluded to.

As regards the sinking of countries, there is no difficulty in
regarding it as the result of an elevation of neighbouring coun-
tries. Yet we can imagine many causes, independent of such
elevations, which may produce depressions. It does not, how-
ever, lie within the scope of these remarks to enumerate these
causes.

It remains to consider the elevations of whole systems of

* Petrificata Suecaua Form. Cretaceao, &c. 1827. P. 81.

M . Arago on Thunder. 8l

rocks, events wliich must have taken place prior to the exist-
ence of our records. There is doubtless no difficulty in also ex-
plaining these phenomena through the agency of steam. Elie
de Beaumont,* however, is of opinion, that these elevations are
a consequence of the inequality between the cooling of the in-
terior and exterior of the earth. We shall examine this subject,
after pointing out the laws that prevail during the cooling of
large masses of fused matter.

(To he continued.)

On Thunder and Lightning. By M. Arago.

M. Arago has lately published a valuable essay on thunder^
for the Annuaire du Bureau des Lojigitiides, in which he
gives a masterly historical sketch of the real facts which have
hitherto been accumulated, and from these deduces the infer-
ences, scientific and practical, which may legitimately be drawn.
With the view of supplying as much of the valuable informa-
tion there coUectecf as our space will allow, we shall in this
number give the ge^j ral results of that elaborate review, from
which, as the authoi anticipated, various truths have been dis-
covered, which the examination of the isolated facts could never
have revealed.

From the earliest times it has been known that sound wa9
not material. Thus, Aristotle knew perfectly that it was pro-
duced by simple undulations of the common air. At the pre-
sent time, this result may, without scruple, and with a single
modification, be extended to light ; for light also is the conse-
quence of the undulatory motion, not of air, but of a certain
very rare and very elastic medium which pervades the universe,
and which it has been agreed shall receive the name of ether.

Are we to range the thunderbolt, whose presence is almost
always manifested simultaneously with light and sound, in the
same category ? Though free to declare myself the decided
partizan of the theory of the undulation of light, I must avow
I remain completely undecided on this other point.

* Poggendorflf's Aunal. vol. xxv. p. 55.
VOL. XXVI. NO. LI. JANUARY 1839. F

82 M. Arago on Lightn'mg.

When, on the one hand, I consider the observations of Mr
Wheatstone as completely established, and when I direct my
attention to the incomparable velocity with which the thunder-
bolt traverses the aerial regions, and the solid bodies which
propagate it at the surface of the earth, I feel myself but little
inclined to regard it as composed of an agglomeration of mate-
rial molecules, or a mass of minute projectiles, and the idea
of undulation seems most readily to comport with such extra-
ordinary velocities. But no sooner, on the other hand, have I
reached this conclusion, than the prodigious mechanical effects
produced by thunder storms, and the transport of the heavy
substances thereby effected, rush to my recollection. And when
to this I add, that, despite of all the delicacy of the methods
employed by operating upon levers suspended in vacuum, with
threads of gossamer, with light concentrated to a focus by the
largest mirrors and most powerful lenses, the slightest devia-
tions have not been produced, then all my uncertainty returns,
and the undulations of the thufiderbolt appear enveloped in ten
thousand difficulties. We hasten, therefore, to a rapid examina-
tion of the principal phenomena brought under review.

Of' Lightning,

The Etrusci, whom all antiquity has celebrated for their
knowledge of the subject of lightning, divided it into three kinds.
The first, according to them, was lightning of information or
advice ; the second produced a certain degree of mischief; and
the third was composed of destructive fire, which struck par-
ticular individuals, ravaged kingdoms, and left nothing which
it encountered in its previous condition. Jupiter, they say,
sported with the first at his w'ill ; the second left not his hand
except at the direction of a council composed of twelve great
deities ; and finally, the third imperiously required a decree of
all the superior gods. It is not easy to imagine how a people
who entertained such ideas should ever thinii of inquiring how
thunder was engendered in the clouds, how it produced light,
and was accompanied with noise. Yet, notwithstanding, these
inquiries occupied a large space in the works of Aristotle, in
the poem of Lucretius, in the writings of Pliny, and in the
Qiiaestiones Naturales of Seneca. This last philosopher has

M. Arago oil Lightning. 8S

summed up, in a few words, the opinions more or less dis-
similar in form, but very analogous in fact, of the naturalists
of antiquity, concerning the origin of lightning : " Fire is pro-
duced by the percussion of flint and steel, and by the friction
of two pieces of wood ; it may happen, therefore, that the
clouds, hurried away by the wind, are likewise inflamed by
means of percussion and friction."" (Ques. N. liv. ii. § 22). I
must request those who are disposed to treat with contempt the
certainly far-fetched analogy we have just read, to consider
how many great gaps two thousand years have still left in the
explication of the phenomena which the celebrated author of
the Qucestiones Naturales had in view.

The fulminating material, whatever the velocity of its pro-
pagation may lead us to suppose, does not move with an un-
defined freedom in solid bodies. This seems evidently proved
by the violent ruptures to which they are exposed, and the
wide dispersion of their fragments. What, then, more natural
than to suppose, that, in traversing the atmospheric air, this
matter pushes the particles of which it is composed violently
before it, whence compression successively results throughout
the entire line of projection ? Smart compressions, as proved
by the pneumatic syringe, are always accompanied with a dis-
engagement of light ; hence, the direction pursued by the ful-
minating matter ought to be marked by a luminous streak.

This line of argument seems quite consistent, whilst, at the
same time, it is liable to several objections. For, first, if in
each point of the line which the lightning traces, it be necessary
for the disengagement of the light that certain considerable
volumes of air be sensibly compressed, then there is difficulty
in conceiving how all these displacements of particles can be
reconciled with the extraordinary velocity of lightning, as de-
monstrated by the experiments of Mr Wheatstone. Again,
the analogy derived from the pneumatic syringe, does not sup-
ply all the support that is desirable. In this beautiful instru-
ment, the atmospheric air is not the only element which plays
a part ; for the experiments of M. Thenard, in fact prove, that,
if the cylinder of the syringe be perfectly clean, and the felt of
the piston be moistened with water, and not with any greasy or
oily matter^ then the compression is not accompanied vriih the

f2

k

84 M. Arago on Lightning.

production of light. It is tliis oily matter, then, which takes
fire in the syringe, in consequence of the disengagement of the
heat which every strong compression of gas produces. And
hence we may remark, in passing, agreeably to the statement of
M. SaissT/ of Lyons, that the experiment does not succeed, ex-
cept with the assistance of the combustible gases themselves.

The kind of lightning known by the name of forked-light-
ning, and in a zig-zag form, has always appeared so astonish,
ing, that individuals have been tempted to regard the appearance
as wholly illusory, and as the result of those irregulai- refrac-
tions to which the atmospheric vapours and the clouds might
subject luminous rays. (See Logan, in the Phil. Trans, vol, 39.)
But astronomers, who so frequently have occasion to examine
the heavenly luminaries through vapours and clouds, without
finding them more disturbed than if the atmosphere were se-
rene, cannot be induced even seriously to refute the strange
conception of Mr Logan. A flash of forked-lightning, in which
the zig-zag or angles are very acute, and still more one in whicli
there are two or three projecting points, presents so violent a
contrast to the regular curves which bodies subjected to the ac-
tion of accelerating forces undergo in their course, that we dare
not, at first glance, entertain the idea that such a flash exhibits
in the atmosphere the situations which one and the same matter
successively occupies. On the other hand, regard this light-
ning not as a material body, but an undulation, and the double,
triple, and other refractions which the luminous waves of cer-
tain crystals exhibit, become so many striking analogies on
which the mind can with complacency rest. We have only,
moreover, to recollect, that the atmosphere contains a great
variety of exhalations, and especially of aqueous vapours, very
irregularly distributed, whence it will result that it may oppose
a variety of unequal resistances to the progress of the lightning.

The lightning, which appears in the form of balls, or fire-
balls, of which we have collected so many examples, afterwards
to be produced, and which are so extraordinary, first of all, by
the slowness and uncertainty of their motions, and then by the
extent of the devastation they occasion in bursting, appear to
me at present, among the most inexplicable phenomena in phy-
sics. These balls, or globes of fire, appear to be agglomera-

M. Arago on Lightning. 85

tions of ponderable substances strongly impregnated with the
very essence of the thunderbolt. How, then, are these conglo-
merations formed ? in what regions are they produced ? whence
do they obtain the substances which compose them ? what is
their nature ? and why are they sometimes suspended for a
long period, only that they may precipitate themselves with the
greater rapidity ? &c. &c. To all tliese inquiries, science re-
mains mute, and can make no reply.

Lightning, in traversing the atmosphere, effects here and
there the combination of its two gaseous elements, and trans-
forms them into nitric acid. Is it then impossible that the same
action may sometimes instantaneously produce a kind of semi-
union of all the different kinds of matter which exist in a given
volume of air ? If this conjecture, which I do not offer in a
detailed form, but express with all ])ossible brevity, should ap-
pear to be inadmissible, I may mention that M. Fusinieri states,
tliat he has constantly found metallic iron — iron in different
degrees of oxidation — and sulphur, in the powdery deposits
which surround the fissures through which the thunderbolt
has passed. Without having tjie slightest wish to revive anti-
quated ideas regarding thunder-stones^^ I shall simply remark
here, that it is not proved that we should absolutely regard as
false the whole of the narratives, in which a fall of various
matters is related to have accompanied thunder storms. What
pretext, for example, is there for considering as untrue the fol-

'^ The pretended thunder-stones which some nations venerated, had ge-
lu'iiilly the form of a wedge, an axe, or of tlie iron point of an arrow
or lance. The origin of these stones is not at all doubtful, since precisely
similar ones have been found among the tools and arms of the natives of
America, and since we have learned how they are made. The ancient Con-
tinent, also, was originally inhabited by savage nations ; and similar rc-
(juirements, and a similar scarcity of ii-on, would produce in it the same
kind of industry. But when the improvement in metallurgy produced
stronger instruments, more cutting and more convenient, stones were aban-
doned, and have since been preserved uninjured below the surface of the
ground. These stones have often been found in the trunks of trees, and
hence it has been contended that they owed their position there to a thun-
der storm — every other explanation was held to be an impossibility. But,
at this rate, it must have been thunder which introduced toads into the
trunks of those trees where they are concealed, and the several pieces of
ancient money which the hatchet is frequently revealing.

86 Sheet Lightning.

lowing fact, which I extract from the works of Boyle. *' In
July 1681, a thunder storm produced a great deal of damage
near to Cape Cod, upon the English ship the Albemarle. A
flash of lightning was followed hy the fall of a hurning bitu-
minous matter into the boat hanging at the stern, which gave
out an odour similar to that of gunpowder. This substance
was consumed on the spot, and it was in vain tlmt they at-
tempted to extinguish it with water, and to sweep it overboard
with a broom.'*

Sheet Lightmr,g.

We may now inquire what is the nature oi eclairs de chalenr^^'
or the lightning which occurs in the course of serene nights.
" In the calmest nights," says Seneca, " with the stars shining
bright, you may see lightnings flash, but doubt not, he adds,
that, in the direction of the lightnings there will be found
clouds which the spherical form of the earth hides from our
view. The flash ascends on high, and appears in the bright
and serene sky, being withal elaborated in some obscure and
dark cloud." (Quest. Nat. v. ii. § 26.) In his dissertation
upon thunder, to which L Academic de Bourdeaucc awarded its
prize of the year 1726, Lozeran de Fesc also did not regard
the^Q eclairs de chaleur as primordial. According to him, they
are the reverberation upon the more or less elevated atmospheric
strata, of common lightning, having its origin in a storm, of
which the direct view is obstructed by the rotundity of the
globe. This explanation is very simple, and has been adopted
by the majority of natural philosophers. What, more natural,
they allege, than to endow the atmosphere with a certain re-
flecting power ? Is it not to it we owe the crepuscular light
which we enjoy so long before the sun rises, and after it has
set.?

Some doubts as to the conclusiveness of this reasoning might
be urged in relation to the subject of quantity. Might it not
happen, it may be said, that the atmosphere, though possessing
a reflecting quality sufficient to transmit the crepuscular light
of the sun, can produce no sensible reverberation on receiving

* The term " eclairs de chaleur ^'^ corresponds to our slieet, sinnmer, or silent
lightning.— Edit.

Sheet Lightning. 87

nerely the comparatively very feeble illumination of lightning?
i\n answer to this query may readily be supplied. In the year
1739, during the course of the experiments which Cassini and
Lacaille were making upon the velocity of sound, the light in
the atmosphere produced by the discharge of a cannon near the
lighthouse of Cette was apparent, when they were situated in
stations from which the town and the lighthouse were entirely
obscured by intermediate objects, as, for example, the moun-
tains of S^t Bauzeli. Again, in the year 1803, M. de Zach used
signals on the Broclien mountain in the Harz for determin-
ing the differences in the longitude, when it was found that
observers placed upon the mountain Kenlenberg, at a distance
of more than sixty kagues, saw the flash from the simple explo-
sion of six or seven ounces of powder in the open air, and this
when the Brocken, on account of the rotundity of the earth, was
quite invisible from the Kenlenberg. Finally, I will add, that
when the guns of the lower battery at the Hotel des bivalides at
Paris are fired, an observer, placed in the walks of the garden of
the Lnxeinboiirg, near the rue d'Enfir (in a spot whence
neither the body of the building nor even the dome of the hospi-
tal can be seen), may still perceive in the sky, the moment of
the discharge, a flash which extends to the zenith, and even be-
yond it. If, then, the comparatively feeble light resulting from
the inflammation of a few ounces of powder is so evidently re-
flected in the atmosphere, what may not be anticipated from
the reflection from the infinitely more vivid flash of lightning !
In these facts enough certainly may be found to establish
the possibility, or the probability, if that idea be preferred, of
that explanation of sheet lightning on which we have been
dwelling. This, however, is not all : we must attempt to
extend to this explanation the character which belongs to the ma-
jority of modern scientific theories, — we must endeavour to pass
from mere conjecture to real demonstration. All that is re-
quired, appears to be supplied in the following observations*
The one I have found in the " Vayage *" of Saussure, and the
other in carefully perusing the two volumes of Mr Luke
Hozcard's Meteorological Observations. In the night between
the 10th and 11th of July 1783, the illustrious historian
of the Alps was an inmate at the Hospice du Grimsel, when

88 Sheet Lightning.

the heavens were peculiarly calm and serene. Nevertheless,
when he cast his eye towards Geneva, he perceived in the
horizon several bands of clouds whence flashes of lightning
issued, without, however, any attending thunder. During
the same night, and at the same instant, the towtr of Ge-
neva was visited by one of the most tremendous thunder-
storms it had ever witnessed. Again, on the 31st of July
1813, Mr L. Howard perceived at Tottenham, near London,
some trifling flashes of sheet lightnings in the distant hori-
zon towards the south-east. The sky was bespangled with
stars, and not a cloud was to be seen in the firmament. Soon
after this, Mr Howard learned from his brother, at the time in
the south-east corner of England, that on that same 31st of
July, at the very time the silent lightnings were perceived at
Tottenham, there raged at Hastings a dreadful storm, which
also extended over France, as far as from Dunkirk to Calais.
Thus, the flashes which were noticed in the atmosphere of Lon-
don were produced in the midst of clouds situated nearly fif:v
Jeagues off.

But the proving that sheet lightning is sometimes nothing
more than reflected lightning, does not establish that it has
always this origin. Those who believe that a sky which is per-
fectly serene is often striated with direct spontaneous flashes,
proceeding from an atmosphere devoid of clouds, may support
their opinion by the circumstance that sheet lightning often ex-
hibits itself, as for example at Paris, throughout whole nights,
and in every quarter of the horizon, without any part of the sky
becoming obscure. At the same time, however, it must be al-
lowed that the prolonged existence of a sort of Oasis of serenity
seems not very probable. So soon as the time arrives, that
there are as many observers scattered over the face of a coun-
try as Meteorology requires, then we shall easily ascertain, by
the comparison of their several journals, whether the sheet
lightning which is seen in any given spot, is derived from the
reverberation of the flashes of a distant storm, or is not so.
Even before the arrival, however, of that happy period, it
seems to me possible to decide the question by observations
taken at a single place, by a single individual, and even at the
very instant the phenomenon is observed.

Sheet Lightning. 89

The instrument required for this purpose is by no means com-
plicated. It must be composed of a tube from twelve to sixteen
inches long, which must have at its further extremity a circular
aperture of about a line in diameter. This aperture must be sup-
plied with a lens of rock crystal, with parallel faces, and about
two lines thick, cut perpendicularly to the edges of a hexahe-
dral prism of rock crystal. At the other extremity of the tube,
to which the eye is to be applied, there must be fitted a prism
of the carbonate of lime, of quartz, or some other crystal which
is endowed with the property of double refraction. The prism
must also be achromatic. If, without the prism, you direct
the tube to a radiating object, or to one simply illuminated,
you will see only a circular disk more or less luminous.
Through the doubly refracting prism, on the other hand, yoii
will perceive two such disks.

When the light of the object observed is direct white light,
the two disks will appear white. If, on the contrary, the illu-
minating light reaches the tube only after having been reflected
at an angle notably different from 90°, the two disks will be
found diversely coloured. Suppose, for example, that the one
is red, the other will be green. The tints moreover will be al-
tered when the tube is turned ; but they will always be the
complements of each other, and their union will produce white.
The light which is reflected by the atmospheric air possesses in
this instrument all the properties of that Avhich is reflected by
glass, water, &c. Thus, if you direct the tube towards the
azure sky, you will perceive that the two disks sparkle with
the brightest colours. There is only a very narrow zone in the
immediate neighbourhood of the sun, and a still more circum-
scribed space situated in an opposite direction, where the co-
loration may not be ])erceptible.

After these details, it is scarcely necessary to add a won!
in pointing out how this simple tube will conduce to the so-
lution of the problem before us. It is now night, the sky is
serene, and from time to time sheet lightning illuminates the
heavens. After having directed the tube towards the quarter
•where the phenomenon most frequently occurs, we attentively
look through it as if it were a common telescope. When a flash
occurs we immediately perceive in the tube two brilliant disks.

k

90 Sheet Lightnivg,

Are they white, or rather, are they of the same shade as the
lightning itself? Then we may certainly conclude that we
have seen direct light, which has not reached the eye in the way
of reverberation ; in a word, that the light has emanate dj'rom
that part of the atmosphere which is situated above the horizon.
On the contrary, is it that the two disks appeared coloured ?
This is a proof that the light enclosed by the crystals in the
tube has undergone a kind of analysis, and is reflected light ;
in short, that it proceeds from lightrmig which has been playing
below the visible horizon. By measuring the intensity of the
colour exhibited by the disks, we shall be able, without much
difficulty, to decide which region of the atmosphere is the seat
of this kind of lightning. But here I must guard against en-,
tering into minute details ; I have said enough to shew how,
by means of a very simple observation, we may dispel all the
doubts which the question concerning sheet lightning has ori-
ginated.

If little attention is at the present day paid to that noiseless
lightning which is produced amo?igthe clouds, it arises from this
circumstance, that the only explanation which has been given
of that lightning, how improbable soever it may be, implies the
production of sound, at least as inevitably as it does that of
light, as the result of the physical agencies it brings into play.
Moreover, there is no expediency in having recourse to the
enormous distances of the thunder-clouds above alluded to,
whilst we have yet to learn why sometimes we hear absolutely
no detonation after very dazzling flashes of lightning. There
is, in truth, no justification for the introduction of these im-
mensely distant sources, which in no case will explain the obser-
vation made hy Deluc in which flashes of the same intensity and
emanating from the same clouds, were followed, some of them, by
stunning thunder-claps, and others with absolute silence. In
addition, should any one require a proof that every noise in the
atmosphere is not necessarily accompanied with the production
of light, he may have it in the fact that zvater-spouts are some-
times the focus of very brilliant lightnings. On the 4th of
June 1814, M. Griswold found himself very near (within 430
yards) one of these meteors in the territory of Illinois. Light-
ning which was almost continuous, and of incomparable briU

Thunder unaccompanied rvith Ligliining, 91

liancy^ descended from the clouds to the earth, at a little dis-
stanee from the external surface of the water-spout, or pro-
bably along that very surface itself ; and notwithstanding, ah-
solutely no detonation was heard.'*

The thunder aoai7i which occni's without lightning may very
readily be explained. Suppose there are two distmct strata of
clouds, and that the one is superimposed upon the other ; sup-
pose that the upper stratum becomes the centre of a great
storm, that it is furrowed by brilliant lightning, and gives out
many loud resounding thunders. If the lower stratum of
clouds is very opaque or very thick, the lightning''s glare, how-
ever vivid, will not be afile to traverse it ; nearly the whole of
it will be absorbed ; and no sensible portion of it will reach the
surface of the earth, whilst, at the same time, as bodies which
are impermeable to light still easily allow the transmission of
sound, the same individual who most distinctly hears the thun-
der may see nothing of the lightning. The two-fold supposi-
tion that the strata of superimposed clouds exist simultaneously
at different elevations in the atmosphere, and that a storm may
Ta-ge only in tiie upper one, might, if required, be supported
by the narratives of so many credible travellers as to leave no
manner of doubt that we have indicated one of the causes
of the occurrence of thunder without lightning. I say, how-
ever, only one of the causes, for instances of thunder-bolts are
not rare, which apparently do not take their rise in the clouds,
and which detonate violently without being announced by any
luminous phenomena.

Concerning ordinary thunder^ — 4he time between it and the light-
ning^— its peals, — thunder-claps, — the extreme distance at which
it may be heard, — the thunder of serene weather, and of the
length of the lightning' s flash.

Sometimes the thunder is not heard till a cmisiderablc tirnv
ajier the flash. This requires some explanation; for no one

* This absence of noise in ilio midst of such dazzling irradiations, is ii
plienomenon which has not been noted by meteorological observers. Mr
Griswold believed, that, in reality, there was sound as in a common storm.
He argues that the rapid whirling motion of the air which constitutes the

92 Interval betzveeti the Flashy

doubts, tlioKgh the matter is Jar from being demonstrated^ that
the light and the noise have been produced simultaneously. At
the same time, the phenomenon is so simple, that even the an-
cients, little advanced as they were in natural science, were ac-
quainted with the true cause. Take up, for example, the Sixth
Book of Lucretius'* Poem, and you will speedily find observa-
tions which are intended to establish that light moves with much
more rapidity than sound. Some verses later, you will also
find, as the inevitable consequence of these premises, that the
lightning"'s flash should reach the earth much sooner than the
thunder^ voice, although both the thunder and lightning had
been formed at the same instant, and'by the same shock.

This explanation is perfectly accurate ; and the only advan-
tage we possess over the philosophers of antiquity, is the power
of assigning for every given distance, the precise time which in-
tervenes between the light and the sound in seconds, and the
fractions of seconds.

Two astronomical phenomena (the eclipses of Jupitefs satel-
lites and aberration)^ have enabled us to prove, that light tra-
verses space uniformly with a velocity of -80 thousand leagues
(French) for every second of time. Hence it follows that it is
only one eight-thousandth part of a second in travelling ten
leagues. But ten leagues, beyond doubt, far surpasses the ele-
vation at which thunder and lightning are produced in our at-
mosphere ; so that disregarding a fraction of a second which is
wholly inappreciable, we may, in all our researches upon thun-
der, safely conclude, that we see the lightning at the very mo-
ment of the flash.

As to the sound, it may be affirmed, according to the most
recent experiments, the temperature of the air being 50^^ Fahr.,
that its velocity equals S68.5 yards (English) per second. If
the cloud, whence the lightning has issued, is at a distance in a
straight line of 368.5 yards, there will elapse an entire second
between the appearance of the light and the arrival of the sound.

jneteor, prevented the sonorous vibrations from escaping from the interior
of the water-spout, and from being communicated to the nearly tranquil air
of the rest of the atmosphere. I doubt, however, whether this explanation,
ingenious as it is, will obtain many proselytes. Most will prefer the idea of
the production of light even without sound.

and the Thunder. 93

A distance of 737 yards will correspond to an interval of 2"

1105.5 3"

* * * * * •♦ «

3G85 10"

and so on in proportion. Hence, then, an observer who shall
have determined with his watch, the number of seconds com-
prised between the arrival of the flash and that of the thunder,
may easily deduce the distance at which he is from the point
from which it emanated. All that is required is, that he shall
multiply this number, whether a whole or a fractional one, by
368.5 yards : the product will be the distance sought after, ex-
pressed in yards.

This result, it should be remarked, is in general the recti-
lineal distance of the cloud, measured upon a line inclined to
the horizon ; it is the hypothenuse of a rectangular triangle,
whose other sides are, on the one hand, a part of the horizontal
line from the place of observation, and on the other, the vertical
height of the cloud from this same horizontal line.

In deducing, from the length of the hypothenuse, the vertical
height of the cloud, we must know the angular height of that
end of the thunder-cloud which is nearest to the point of obser-
vation ; we must know if it be at an angle of 10°, 20°, or
45°, &c. This elevation may be measured with sufficient
precision by means of a graphometer, or of a theodolite, or of
a reflecting instrument, by taking as a mark — the point to
which we direct it, — the nearest striking peculiarity of form, or
of illumination, which we notice on the thunder-cloud, of which
no such cloud is ever devoid. This angular height ascertained,
the desired calculation is completed by a dash of the pen.

By the process now described, the absolute height of clouds
has frequently and satisfactorily been established ; and this
kind of observation has been assuredly too much neglected.
Meteorology is much interested in its further extension. The
intervals longest and shortest, between the flash and the thunder,
ought especially to fix the attention of philosophers; the forme^^
inasmuch as they will immediately contribute to the determina-
tion of the greatest elevation of thunder clouds, and the latter,
on account, of their possible connection with a long contro-
verted question, on which I shall here make a few remarks.

When a second of time elapses between the flash and the

94 Ascending Lightning?

thunder, the clouds are at an elevation at most of 368.5 yards
of perpendicular height ; when the interval between the two
phenomena is i a second, the height of the clouds cannot be mor^^
than 184 yards ; and when there is an interval of y*^, ^-^^ /^j,
and ^^ of a second, then the heights of the lowest clouds will
respectively correspond to about 148, 111, 74, and 37 yards.

The weather-cock on the dome of the Invalides has a ver-
tical elevation of 112 yards. Suppose, that, during the time
of a storm, an observer placed near the monument were to
perceive one of these flashes, which do not appear to quit the
clouds^ and he was also sure that the thufider succeeded the
lightning, after a short interval of -^-q of a second. It would
result, as we have just seen, that the clouds, the supposed focus
of the lightning, could not be more than 111 yards in height,
and that they must have enveloped the weather-cock of the
dome. But if the weather-cock has remained free, and if the
clouds have been always higher, it will then he proved that the
detonation has not been produced in the midst of them, and the
theory of ascending lightning might then produce in its favour
an argument which would be almost irresistible.

At Strasburg, where the steeple reaches an elevation of 155
yards, the same mode of observation might be extended to the
case in which there was an interval between the light and the
sound, amounting to 1% of a second. In the vicinity of moun-
tains, if we had previously determined a certain number of well
defined points, it would be easy to advance to entire seconds.
Finally, entire seconds of interval, would be no where an ob-
stacle to the application of the method, if recourse were had to
balloons, with whose help the exact height of clouds might be
determined ; or at all events, their inferior limit.

I know not if I be at all deceiving myself, but sure I am
that observations of this sort peculiarly merit the attention of
philosophers. How interesting would it be to put an end,
by a simple comparison of figures, to the interminable question
of ascending lightning, that is to say, of lightning which it
is supposed must ascend from the earth. As for those who
suppose that there are two currents, one ascending, and the
other descending, which invariably co-operate in the production
of these phenomena, they probably may find in the same set of

Distance at which Thwider is heard. 95

experiments, provided they were made in two places at the same
time, wherewithal to determine in which current the detonation
is produced. Finally, would it not confer a high degree of pro-
bability on their system, if, for example, the focus of these de-
tonations were discovered to be between the clouds and the
earth?

Before leaving the numerical data upon which we have been
dwelling, we shall endeavour also to determine the greatest dis-
tances to which it is ascertained the sound of thunder has ever
extended. We have already had occasion to allude to the fact,
that De VIsle once reckoned 7^ seconds between the hs^ht-
ning and the thunder. This number, the most considerable
mentioned in the annals of meteorology, multiplied by 368,
gives for the distance of the cloud whence the lightning ema-
nated, 26,496 yards, or about 15 miles English. After tliis soli-
tary result of 72 seconds, the next longest period which I have
met is 49 seconds. This number, multiplied by 368, gives
18,032 yards, or about 10 miles. According to these data, the
greatest distance at which tiiunder has ever been heard, is lit-
tle more than 15 miles, and the greatest ordinary distances do
not amount to more than about 10 miles.*

The small extent of the distance, according to these results,
cannot fail to surprise most people, especially when they r^em-
ber how much further the report of cannon extends. Thus, for
example, I find that the discharge of the cannon at Florence
sometimes extends from the old castle of Monte- Kotondo nearly to
Leghorn, a distance, in a straight line, of 20^ leagues (upwards
of 50 English miles). Also, when they fire the cannon at Leg-
horn, the report is sometimes heard at Porio-Ferraio, at a dis-

* It maybe gratifying to supply here some limits of distances which have
been determined by direct methods. On the 25th of January 1757, a thun-
derbolt fell with iiji-ight/nl crash upon the steeple o{ Lesttritliid, in Cornwall
and nearly entirely destroyed it. The celebrated Smeaton was then about
30 miles distant, Avhence he saw the lightning, but did not hear the slightest
noise. Muschenbroek mentions that it frequently thundei"S very violently
at the Hague, without being at all heard at Leyden, a distance of 4 leagues,
or at Rotterdam, a distance of 5^. There are also instances noted of very
violent thunder-storms having occurred at Amsterdam, whilst no intimation
of it could be perceived, so far as sound was concerned, at Leyden, a distance
of 9 leagues.

96 Distance at which Thunder is heard.

tance of 20^ French leagues. Once more, at the time that the
French were conducting the siege of Genoa, the noise of their
artillery was heard at Leghorn, a distance of 36| leagues (up-
wards of 90 English miles).

The shortness of the distance which suffices completely to
subdue the noise of the loudest thunder has excited astonish-
ment in all countries. Thus, I find in the Memoires des Mis-
siannaires de la Chine, t. iv., that the Emperor Kang-hi, who
made learned researches concerning the phenomena of thunder,
regarded 10 leagues as the greatest extent to which the detona-
tions could reach ; whilst he satisfied himself, on the other
hand, that he had perceived the noise of artillery to the distance
of 80 leagues. The object of our researches should now be to
discover whether the great cause of the obscuring of the sound,
on which we have so long been dwelling, is not exclusively the
partial reflections to which it is subjected in obliquely encoun-
tering the different substances which separate the atmospheric
strata of different densities.*

* We know, generally, exceedingly little concerning the different canses
which exerl an inflvience npon the intensity of sound, and concerning their
mode of action. Derham alleges that sounds extend farther, and are more
distinct in -winter, and especially during frost, than in summer. This opi-
nion lil^s been confirmed by Captain, now Sir Edward Parry. I read in his
first voyage — " The distance to which sounds extended in the open air, so
long as the intense cold continued, was extremely great, and invariably
excited our surprise, in spite of the frequent opportunities we had of mak-
ing the remark. For example, we often heard men who Avere convers-
ing at their usual tone, at the distance of a mile. On the lltli of February,
1 heard, even at a greater distance, a man who was singing to himself as lie
walkcxl along the beach." Derham thought likewise, that he had noticed
that new fallen snow is an agent in moderating sound, much more power-
ful, tliau that which has lain for a time on the ground, and whose surface
has become united by a crust of ice. He also says, that mists very consi-
derably destroy sonorous undulations. It is probable that those mists, which
are uniformly distributed, probably produce the effect announced by tlie
JEnglish philosopher ; but in other circumstances they produce quite a con-
trary effect. Thus, in November 1812, the atmosphere being covered to a
slight elevation, with a thick and continuous stratum of mist, Mr Howard
distinctly heard the noise of the carriages upon the stones of London, thougli
he was then at a mean distance from the town of not less than five miles.

The observations of M. de Humboldt, made upon the banks of Oronocco,
cave completely established that sound propagates itself further during the

Distance at which Thunder is heard. 97

By means of the results we have just obtained concerning the
extreme distances which the noise of thunder reaches, we shall
be able to determine the important question, whether we must
regard the thunders occurring in serene and beautiful days, as
the murmurs of common thunder which has been elaborated in
the midst of clouds which are situated below the horizon, or
whether we are to consider them as thunders which are pro-
duced, and have broken forth, in the midst of the purest at-
mosphere. The following are the links by which these two
kinds of truths may be connected.

If the horizon is quite clear, a man whose eye is elevated about
five feet (1™.6) from the ground, may see an object on tlie earth at
the distance of 1 league (of 4000 metres), about 2| miles Engl.

If the object is elevated 82 ft., he may see it at the distance of 64 leagues.

1640 do. do. 21 ...

3280 do. of more than 29

Let US now consider an observation of Volney's, whose accu-
racy is well known. On one occasion, when at Pontchartrain,
he very distinctly heard four or five peals of thunder. He
looked carefully around him, but could perceive no cloud, either
in the firmament, or near the earth. If these five peals did not
originate in the diaphanous atmosphere which covered the visible
horizon ; — if their focus, or cause, must be sought for in clouds
which were situated beyond the limitsof this horizon, these clouds
could not be at a greater distance than six leagues (15 miles) ; for,
were this the case, the detonation could not have been heard :
moreover, clouds that were invisible at the distance of six leagues
could not have possessed an elevation of more than about 98 feet.

night than during the day. Is it equally certain that the difference depends,
as my illustrious friend ingeniously supposes, upon the currents of hot air
which rise from the soil to the upper regions of the atmosphere, during the
daytime ? It is an opinion very generally entertained, that the wind, when
it blows in a direction contrary to that in which the sound is proceedmg, con-
siderably diminishes its intensity. Facts, on this point, confirm tlie general
belief. This, however, is not true, of another opinion which is not less gene-
rally prevalent, viz. tliat those winds which are blowing in the stune direc-
tion with any aiven sound, aid its transport, and maintain its strength. The
observations of M. F. Delaroche seem to establish, that if there are winds,
which, so far as intensity is concerned, oppose its progress, there exist none
which favour it.

VOL. XXVI. NO. LI. JANUABY 1839- ^

98 On the Cause of Thunder.

Hence we are brought to this alternative, either that the thunder
heard by Volney proceeded from an atmosphere which was per-
fectly serene, or it was produced in clouds, which were situated,
at the most, at the insignificant height of 98 feet. Of these two
hypotheses, it appears the choice should be so much the less doubt-
ful, since the clouds which, an hour after the thunder was heard,
covered the atmosphere at Pontchartrain, were majestic hail
clouds. But whatever may be the value of this reasoning, so
far as the particular observation which occasioned it is con-
cerned, it is not the less certain, that after hearing thunder with
a serene sky, we ought carefully to inspect, looking all round,
if there be no clouds beginning to appear in any quarter of the
horizon.*

In deducing these important consequences from the deter-
mination of the interval of time which elapses between the ap-
pearance of the lightning and the noise of the thunder, it has
not been necessary that^we should know the physical cause
to which thunder is to be ascribed. The researches which
have been undertaken to discover this cause, ought not, how-
ever, the less to be mentioned in this place, although they have
not been attended with all the success which was desirable.

A smart clap of our two hands produces a very considerable

* In considering the above observation of Yolney with all attention, I
cannot go the length which this able man did when he concluded that thun-
der might certainly proceed from serene skies.

Pliny reports, that at the time of Catiline's conspiracy, a municipal De-
curion of Pompeii, Herennius by name, was struck by lightning which
proceeded from a sky without clouds : he does not however state, whether
thunder accompanied the lightning ; and, therefore, this quotation leaves
the question very much where it found it.

Suetonius informs us, " That after the death of Caesar, a circle like the
rainbow was seen in the clear and serene sky, to surround the disk of the sun,
and lightning struck the monument of Julia, the daughter of Ca}sar. We
know, at the present day, that no circle similar to the rainbow, and that in
fact no circle, whether a halo, or a simple arch, could possibly appear round
the sun in a sky that Avas quite clear and serene. . The historian should
have been contented with remarking, that the phenomenon occurred at a
time when the sky generally was clear. It ought likewise to be noted, that
he says nothing here of thunder. The event mentioned by Crescentius
raises the same kind of doubts. This author very decidedly declares, that
on one occasion near the island of Procida about mid-day, ichen the sky teas

071 ttie Cause of Thunder, 99

noise ; what result, then, may not be expected from the col-
lision of two enormous clouds ? Such in substance is the idea
which Seneca had formed concerning the noise of thunder.
(Qusest. Nat. lib. ii. §27.)

Descartes, as it appears to me, has done little more than re-
peated the explanation of the author of Quctstiones Naturales,
and attempted to strengthen it by a comparison. " As to vio-
lent storms,**' he remarks, *' which are accompanied with whirl-
winds, thunder and lightning, those which I have been able to
examine, leave no doubt on my mind that they are caused in the
following manner : when it happens that a number of clouds col-
lect one above another, it is no uncommon circumstance Jbr the
more elevated to descend violently upon the lower ones, in the same
manner, as I remember formerly to have seen in the Alps, about
the month of May, that the snows being warmed and moistened,
and so made heavier by the sun, the slightest commotion in
the air was sufficient to cause the sudden descent of a great mass,
known under the name of an avalanche, which resounding in the
valleys, was not unlike the sound of thunder."*"* A single word,
however, is sufficient to demolish this explanation, viz.. It of-
ten thunders when there are not two strata of clouds in the at-
mosphere.

Seneca and Descartes employ the alleged sudden approxima-
tion of two superimposed strata of air, in the condensation of a
certain bulk of air, whose dilatation again, equally sudden, pro-

serene, the lightning struck iJie Ste-Lucie, a galley of three banks of oars,
where the Cardinal of AiTagon was dining, that it injured the rigging in
various places, killed two galley-slaves, as well as injured two other galleys.
The inquiry here occurs, did thunder attend the production of all this in-
jury, and on this point we have no information. Might not then the dam-
age result from the fall of aerolites ? This is a question it is now impos-
sible to answer.

In the Memoirs of Forbin, we read, under date of the year 1686 : * When
the sky was very serene near the strait of La Sonde, we heard a loud peal
of thunder, similar to the noise of the discliarge of a shotted-gim : the
lightning loudly whistling past us, fell into the sea at about the distance of
two hundred paces, and continued to hiss in the water, making it boil up
for a considerable space of time. All these circumstances so very much re-
semble the phenomena which accompany the fall of a great aUrolitHf that it
is only natural to believe that the detonation, the hissing, and the boiliog
up of the sea described by Forbin, depended upon one of these meteoES.

g2

1 00 On Peals of Thunder.

duces the noise of tluinder. Their successors likewise have
made use of the atmosphere in the explication of the phenome-
non, but nearly in the i-everse way. They believe that the
lightning in its passage produces everywhere a vacuum. The
noise then, according to them, is the consequence of the rushing
in of the air, and is similar to that produced in experiments
with bladders. The sudden entry of air into a vacuum, will
unquestionably produce noise ; and if the lightning produces
a vacuum in traversing the atmosphere, thunder will be the con-
sequence. But here we have to inquire, by what physical cause
is it that the lightning produces a vacuum ? and to this ques-
tion no answer has hitherto been returned. Hence it follows
that an explanation of thunder has still to be discovered ; for
all that has yet been done has only been to set aside one diffi-
culty, and to substitute a greater.

But, whatever may be the physical cause of the detonations
of thunder, we have still to inquire what is the origin of those
long rolling peals {roiilements) which every one has remarked,
and of those sudden changes in its intensity, which are so often
repeated, and which are known under the name claps of thun-
der {eclats).

For a long time peals of thunder were regarded merely as
products of so many echoes. This explanation has since been
abandoned in the same hasty way in which it was adopted.
Let us now inquire, therefore, what place a serious discussion
ivill allow us to assign to it.

All those who have witnessed a thunder-storm in a valley
surrounded with high mountains, know well how many local cir-
cumstances may give a resounding, intense, and continuous
character to the various peals. We have not then to inquire
whether sometimes echoes play a part in these phenomena;
the question is, xvhether they are always the cause of the peals
which occur.

I have noticed many instances in which the thunder-peal has
continued for thirty-six, forty-one, and even forty-five seconds.
Has it then been proved, that echoes can produce sounds for
so long a period ? What occurs to me at this moment, as the
longest instance of any echo I have ever heard of, is an observa-
tion of my friend the Rev. Mr Scoresby. When near the lake of

On Peals of' Thunder. 101

Killarney, in a spot which the guides pointed out to him, Mr
Scoresby heard the noise of a pistol-shot for half a minute* We
require for our present object three-quarters of a minute at least ;
but we may be allowed to suppose, that had the resounding noise
of a cannon been substituted for that of a pistol, the thirty
seconds would have increased to forty-five seconds, or even
more. The intensity, I conceive, merits better to be taken in-
to consideration in this case, than in a locality in the neighbour-
hood of Paris, which, so far as I know, has never been cited as
any thing remarkable on the score of echo, viz., that one at the
foot of the tower of Montlhery, where the experiments upon
the velocity of sound were conducted, in the month of June
182^, by Messrs de Humboldt^ Bouvurd^ Gay-Lussac, audEmile
de Laplace. On this occasion they heard the echo from the dis-
charge of a cannon quite near them for from twenty to twenty-
five seconds. We may thus then hope to arrive at something
decisive concerning the exact part which echoes produce in
thunder peals.

Mariners assure us, that in the wide ocean, thunder is ac-
companied with prolonged peals as on land, although there the
sound cannot be reflected either by long walls or by rocks, or
by woods, hills, or mountains. Those who adduce this enu-
meration, seem to forget, or rather they would appear not
to admit, that the clouds possess the power of reflecting
sounds. Muschenbroek, notwithstanding, has remarked, that
in the same locality in which, when the heaven is serene, the
discharge of cannon is attended with a single and distinct re-
port, the sound is often repeated when the weather is cloudy.
Does this observation of the Dutch philosopher appear not suffi-
ciently circumstantial to be admitted ? I shall extract from
a note which I published in 1822, some remarks relating to
experiments on the velocity of sound. " It has happened, that
at Ville-Juif we have four times heard, at an interval of two
seconds, two distinct reports of the cannon discharged at Mont-
lhery. On two other occasions the report of the cannon was
accompanied by a prolonged peal. These phenomena never
happened except at the time when clouds were visible ; when
the sky was perfectly serene the report was single, and did not
continue longer than a moment.*"

i 02 On Peals of Thunder.

In order to prove that peals of thunder do not always and
solely result from reflected sounds, we adduce an observation on
which such an opinion might be supported. On this occasion,
the sky is covered uniformly with clouds; a flash of lightning
issues from the zenith ; in less than two seconds the thunder
breaks forth, and a long peal follows ; a little while afterwards,
another flash cleaves the cloud in the same zenithal region^ the
thunder follows, but this time, the clap, though exceedingly
loud, is sharp and of no continuance. How are these great dif-
ferences to be explained, when we make the rolling peal of
thunder only a simple phenomenon of echoes ?

Dr Robert Hooke, one of the most productive and ingenious
authors of whom England can boast, was, I believe, the first
who, in his explanation of peals of thunder, introduced an im-
portant consideration, unfortunately too much neglected by the
majority of modern philosophers. I allude to the essential
distinction which he has established (in his Posthumous Works,
printed in 1705, p. 424), between simple lightning and com-
pound or multiplied lightning. Every example of the former,
remarks the author, occupies but a point in space, and pro-
duces only a short and instantaneous noise. The sound of the
latter kind, on the contrary, is a prolonged peal, because the
different parts of the long lines to which these flashes extend^
being in general at different distances, the sounds which they
produce, whether successively, or in the same physical instant,
must occupy spaces of time gradually unequal in reaching and
striking the ear of the observer.

This ingenious view of Dr Hooke was again introduced to
notice by Professor Robison, fifty years ago, in the Encyclo-
paedia Britannica. As its adoption by such an individual
ought to recommend it to the attention of meteorologists, I shall
here introduce the lines which the celebrated Professor of
Edinburgh devoted to the subject. " On one occasion I no-
ticed a flash of lightning parallel to the horizon, which might
be about three miles in length. It appeared to me co-existent,
and no one could say at which end it commenced. The thun-
der was composed at first of a very sharp clap, and then of an
irregular peal, which continued for about fifteen seconds. I
imagine that the detonations happened simultaneously in the

On Peals of Thunder. 103

vast extent of the flash, but that they were not throughout of
the same intensity. Different portions of the sonorous agita-
tion would reach the ear by means of the sonorous undula-
tions of the air ilie one after the other ^ and the effect of this
would be a prolongation of the sound. Such also would be
the experience of a person placed at the extremity of a long file
of soldiers who should fire their muskets at the same instant.
This individual would also hear an irregular sound, provided
the muskets were not loaded precisely alike in the different
parts of the line." Let us pursue this comparison of the file
of soldiers all discharging their muskets at the same moment^
and we shall thus see how it may happen that flashes of light-
ning of similar lengths in appearance, nevertheless occasion such
different sounds and peals. Suppose first, to direct our ideas,
that the file is rectilinear, and that there is a yard's distance
between each soldier and his neighboui^ Let us, moreover,
stippose that the observer, placed at one of the extremities of
the line, is, for example, at a yard's distance from the first sol-
dier. The noise of the muskets of the 1st, 2d, 3d, lOOth, &c.
&c. soldier, would reach him the ^J^, j§^, yg^, \%% of a second,
&c. &c. after the discharge. If there were 368 soldiers in the
line, the sound would continue 1 second^ although, in reality,
all the pieces were fired simultaneously. Were there 736 sol-
diers, the sound would last for 2 seconds; if 1105, for 3 se-
conds; if 3680 for 10 seconds, and >so on, always propor-
tionably, in succession.

The file of soldiers still continuing rectilinear, let us now
place the observer upon some point of a perpendicular drawn
from its centre. The report that would then first strike his
ear, would be that from the musket of the soldier in the middle
of the file, or, in other words, the point whence the perpendicu-
lar was drawn. There would then successively reach him, and
in couples, the reports of the muskets of each two soldiers
. placed symmetrically as to the centre of the line ; the rolling
noise would terminate by the report proceeding from the dis-
charge of the muskets situated at the two extremities.

Let us now substitute a circular for a rect'dinear line, and
let us place the observer in the centre. In this position, the
distance of the observer from all the soldiers being the same

104 On Peals of Thunder.

he would 110 longer perceive a long continued rolling, but in
its place a single detonation produced by the union of the noises
of all the inushets.

Surely it is not necessary to say more to enable every one to
comprehend the close connection there is between the thunder-
daps and the zig-zags of lightning. When a flash which is pro-
ceeding in a direction which abuts on the eye of the observer,
so folds itself as to appear for some instants in front, there is
enough to shew that an augmentation of the noise should be
the consequence. Nor is it less evident that this augmenta-
tion will be followed in its turn by a decided diminution, if, by
a second inflection, the lightning is again led away in the di-
rection of the visual line, and so on again and again. But not-
withstanding this, observations made with the purpose of put-
ting the intimate alliance between the zig-zags of lightning and
the peals of thunder Imong the number of demonstrated truths
would have a high interest, and may, therefore, be peculiarly
recommended to the attention of philosophers.

Whoever has at all reflected upon the progress of the human
mind, will not attach much importance to theory, except in so
far as it is connected with observations, and the links which it
suggests and gives ; unless thus directed the satisfaction it af-
fords is small. The kind of merit at which we have just
hinted is, we will venture to say, possessed b}^ the theory we
liave offered of thunder. It in fact supplies us, if not with
the true lengths of the flashes of lightning, at least with evi-
dently the minirmtm valuations ; which, at all events, is some-
thing. Suppose a flash of lightning wholly situated on one
side of the zenith ; let us then draw two visual lines from its
two extremities ; supposing these two rays and the flash recti-
linear, they will form a triangle in which the eye of the ob-
server will be placed at the inferior angle. In every triangle
of this sort, one side is smaller than the sum of the other two.
We may estabhsh, then, the following inequality^ viz. that the r
visual ray between the eye of the observer and the most dis-
tant extremity of the flash is smaller than the sum formed by
adding the length of the flash to the length of the ray between
the eye and the nearest extremity of the flash. But iUwo quan-
tities are unequal, they will remain unequal when they both

On Peals of Thunder. 105

undergo the same diminution. Let us cut ofF from the two
lengths placed in comparison in the preceding inequality, the
shortest visual ray, extending from the flash to the observer''s
eye, and there will remain, on the one hand, the difference be-
tween the longest and shortest visual ray, and on the other, the
short visual ray -f the length of the flash — the short visual ray,
or in other words precisely the length of the flash. It thus re-
mains established that the difference of the two visual rays in
question is smaller than the length of the flash of lightning.
When this difference can be valued in yards, we have then the
minimum limit for the length required. Let us now, then, in-
quire if the valuation of the difference of the two visual rays in
yards be possible.

Why is the flash of lightning followed by a peal of thunder ?
Because its different parts are, in general, at unequal distances
from the observer. How long is the duration of the peal ?
This duration, we have already explained, is the time which the
sound requires to travel, an interval equal to the difference
of the length of the two lines extending from the two extremities
of the flash. Multiplying the number of seconds which the
peal has continued by 368.5, we have, in yards, the difference
of the two visual rays extending from the two extremities of the
flash, just as if it were possible to measure this difference in
space. The result of the multiplication will be the minimum
limit which we require. Example. — It has already been noticed
that M. de VIsle observed at Paris, in the year 1712, thunder,
whose peals lasted 39, 41, and 45 seconds. B}' multiplying
these three numbers by 368.5, we shall have respectively
14,371.5; 15,108.5; and 16,582.5 yards, that is to say, that the
corresponding flashes had a minimum length, 3.3 leagues ; 3.4
leagues ; and 3.8 leagues. Who would have expected these
enormous results ?

For the purpose of definitely fixing our icfeas, I have sup-
posed, in the foregoing instance, that the flash was situated
wholly on one side of the zenith. Any other hypothesis, how-
ever, will in no degree affect the results we have obtained. The
calculated limits (for, wanting an angle, we have been able only
to discover the limits) will only be in these coses still farther
below the real length of the flash.

106 Odour of the Thunderbolt.

Concerning the odours developed by the thunderbolt.

Some philosophers have supposed that there was no necessity
for inquiring into the particular causes of the perceived odour
in each flash of lightning. They have insinuated that the ful-
minating matter in its more or less abundant passage through
the nervous papillae of our organs, may itself excite a move-
ment analogous to that which results from any given odour.
This opinion might to a certain degree be admissible if the
subject related only to smells which were experienced at the
moment. But the thunderbolt, wherever it passes, occasions,
even in the open air, odours which are perceptible for a long
time. Again, when lightning forces its way into a confined
situation, its passage is followed by sulphurous vapours, through
which the eye cannot penetrate. There is evidently, therefore,
some substance disseminated through the air. Are we to sup-
pose that these substances are carried along with the lightning
in its course, as were those powdery deposits examined by M.
Fusinieri, and which have contributed to supply a commence-
ment to our explanation of fire-balls ; or rather, do they pro-
ceed from the sudden evaporation of the different substances
which are contained in the new or old wood, varnished or un-
varnished, in the walls, stones, soils, &c. &c. through which the
lightning has passed ? These are points which in our present
state of information cannot be determined : and whatever may
be the fate of these proposed explanations, we must not be too
confident concerning the alleged uniformity of the nature of
the developed odour. I have found, in truth, that if, in most
instances, it has been stated to resemble the smell of sulphur ;
on other occasions it has been compared to that of phosphorous,
and not unfrequently to nitrous vapour. The odour of nitrous
gas, as will afterwards be pointed out, could more easily be ac-
counted for.

Lightning instantly melts many substances, and produces immediate
vitrification ; it shortens those metallic wires along v^hich it runs,
and pierces holes in the bodies it encounters in its progress.

The details upon these interesting topics appear in another
part of this essay, and I have here but few general remarks to
offer concerning them. I must observe, however, that we are

Transportation of Masses of Matter hy Lightning, 107

completely ignorant of the manner in which so much heat is
so suddenly developed. — Concerning the number of small aper-
tures which are sometimes produced by the passage of lightning
through metallic plates, methods connected with the agglome-
ration and propagation of the fulminating matter have been
suggested, whose least fault is, that they give no explanation of
the opposite directions in which it appears to pass, as shewn
by the shape of the aperture. These opposite directions would
go to shew that two opposing currents had encountered each
other on the surfaces of the struck bodies. In the Giomale de
P. Confiliachi and G. Brugnatelli, 1827, p. 355, I have recently
noticed an observation by D. Fusinieri, which appears to me
very remarkable, as it would thence appear that the holes vnth
ingoing and protruding edges are not formed in the point at
which the lightning first strikes the object. I shall give a
translation of the words of the Italian philosopher : — " On the
25th of June 1827, about 8 p. m., the house No. 1349 of Vi-
cenza was struck with lightning. A horizontal white-iron spout
was the first object struck. This half circular spout was lacera-
ted to the extent of four or five inches. A vertical circular
tube of the same metal, for the discharge of the rain water,
which was connected with the spout, was pierced with three
holes. The upper hole, an inch in diameter, shewed no irre-
gularity of its edges either by their being turned inwards on
the one side, or outwards on the other. Six inches farther
down the tube, there was a second hole, nearly circular, of half
an inch in diameter, with its edges turned inwards ; and lower
still, at the distance of three inches, another hole was remarked,
of equal dimensions \vith the last, but with its edges decidedly
protruding!'^ — The contraction of the wires seems to be the con-
sequence of the efforts which the fulminating matter makes to
escape transversely, as is manifest to the eye by the light which
escapes in this direction. But I shall no longer insist upon these
vague observations. New experiments and new observations
can alone assign to them their proper place in the science.

On the transportation of masses of matter effected by lightning.
Bodies in motion produce mechanical effects dependent at
the same time on their weight and velocity. However small,

108 Transportation of Masses of Matter hy Lightning.

then, the weight or mass of the matter of lightning may be, if
we endow it with sufficient velocity (and its limit in this respect
has not hitherto been defined), we shall easily arrive, so Jar as
intensity is concerned, at all the singular facts which we have
accumulated, and shall afterwards detail. But these flashes of
lightning excite our interest not solely on account of their
power. It has also been remarked that the debris of bodies
struck with lightning, have sometimes, or, we ought rather to
say, have usually been violently scattered in all directions. This
circumstance will be very inadequately accounted for by any
explanation of the mechanical effects of lightning which shall
be based solely on the shock or the clashing of bodies ; but,
on the contrary, it will very readily comport with the hypo-
thesis that the lightning, by its presence, developes, in the very
substance of those bodies which it traverses, some fluid which
is eminently elastic, and whose power must evidently operate
in every possible direction. AVould any one hazard much, by
supposing that the elastic fluid in question is nothing else
than steam ? The matter of lightning melts, or at least, sud-
denly produces incandescence, in small metallic wires : may we
not hence conclude that it will also confer incandescence upon
any fine thread of water which it encounters in its passage ?
By consulting the table which M. Dulong and I prepared
concerning the elastic power of steam, it will be found that
it amounts to 45 atmospheres when water attains an elevation
of 260'' cent. (500° Fahr.) What, then, would not this power
be if the temperature amounted to the much higher one of
red-hot iron ? Such a power would be evidently sufficient, so
far as intensity is concerned, to explain every thing that is
known concerning the mechanical action of lightning. Those
who prefer a fact to a theoretical deduction, have only to con-
sult founders concerning the terrible effects which result from
the presence of a single drop of water in one of their moulds
at the time that the running flaming metal enters it, and then
he will very directly arrive at the same conclusion. If we sup-
pose moisture in the fissures and cells of common building stone
struck by lightning, the sudden development of steam would
break it, and the fragments would be projected to a distance
in all directions. Under the same circumstances, the sud-

Effects of Lightning on Wood. 109

den transformation into a highly elastic vapour, of the water
commingled with the strata on which the foundations of a
dwelling-house repose, will be sufficient to uplift the entire
house, and transport it, as has been actually the case, to a con-
siderable distance. When the celebrated Watt for the first
time saw the enamelled hollow tubes, which lightning had pro-
duced in a mass of sand, he exclaimed '' See here an effect of
the elastic force of steam which the lightning has produced in
traversing the sand." At the same time, nothing appears to
me to indicate more clearly and directly the action of aqueous
vapour, than the singular tearing into shreds which wood un-
dergoes when it has been penetrated by lightning.

LightniTig cleaves wood in the direction of its length into a number
of thin lathsy or into still smaller fragments,

A flash of lightning struck the Abbey of St Medard de Sois-
sons in tlie year 1676, and the following is the description of
its effects, on some of the rafters of the roof, by an eye-witness :
" Some of them were found to the depth of three feet, divided
almost from top to bottom into the form of very thin laths ;
others of the same dimensions were divided into the form of
long and fine matches; and, finally, some were divided into
such delicate fibres that they almost resembled a worn-out
broom.*" Let us now proceed to green-wood, and we shall find
that the effects are analogous. On the 27th of June in the year
1756, the lightning struck at the Abbey of Val, near the island
Adam, a large isolated oak 52 feet high, and somewhat more
than four feet diameter at its base. The trunk was entirely
stripped of its bark. This bark was found dispersed in small
fragments all round the tree, to the distance of thirty and forty
paces. The trunk, till within about two yards of the ground,
was cleft longitudinally into portions almost as thin as laths.
The branches were still connected with the trunk, but they
too were deprived of every particle of bark, and had been
subjected to the most remarkable longitudinal slicing. The
trunk, branches, leaves, and bark, did not exhibit any trace
of comhustion, only they appeared completely dried up and
withered.

110 Effects of Lightning on Wood,

On the 20th of July of the same year the lightning struck a
large oak in the forest of Rambouillet. On this occasion the
branches were totally separated from the trunk, and dispersed
around with a certain degree of regularity. They did not appear
to be withered, and their bark seemed sound. The trunk itself
had not been pealed clean, but, hke the oak of the island Adam,
it had become a mere bundle of laths : there was also this dif-
ference, they were prolonged in this form to the very ground,
instead of the process being arrested at a certain height.

I cannot resist the desire I feel to cite a third case, of which
Professor Munke has given an account, in Poggendorff's
Annals. The diameter of the oak examined by the Ger-
man philosopher was upwards of three feet, at the level of the
ground. The entire trunk of this great tree disappeared ; or,
to speak more accurately, the lightning had separated it in-
to shreds many yards long, and between a line and a line and
a half in thickness, similar to the portions that a gouge would
have detached. Three branches, from 20 to 24 inches in dia-
meter had fallen vertically, cut clean through as if by a single
stroke of a hatchet ; they preserved their leaves and branches.
Not the slightest traces of inflammation or carbonization were
perceived. The total absence of carbonization, the division of
the trunk of the tree into such numerous and delicate filaments,
the dispersion of these filaments into a thousand different di-
rections, all this, I repeat, appears to be the necessary conse-
quence of the action of some elastic force which had developed
itself between the fibres of the wood. By means of a flash of
lightning suddenly transformed into steam, the hygrometric wa-
ter which is contained in the old rafters of a roof, and in the sap
which fills the longitudinal capillary tubes of a growing tree,
and you will produce in every particular the phenomena of the
rafters at the Abbey of St Medard de Soissons, and of the oaks
of the island Adam, of the forest of Compiegne, &c. &c.*

* Lightning often strikes trees quite dead, whilst the external and con-
spicuous damage is altogether trifling. Mr Tull, the author of The Philo-
sophy of Agriculture^ is of opinion that this effect is the consequence of the
rupture of the small vessels, across which the lightning has forced its way.
According to our view, the lightning in this case acts mechanically, as does

On Ascending Lightning. Ill

The minute discussion, which occupied us in another part of
this essay, concerning the transportation of ponderable sub-
stances produced by lightning, demonstrates that these curious
phenomena can be explained without having recourse to any
pretended nexv principles of natural philosophy. This other
result may be also drawn from it, viz. that we cannot deduce
from the direction of the transportation produced by the light-
ning, the direction of the course of the meteor itself; and that
the researches of those, who, supporting their opinions on a
similar basis, have discussed the phenomenon oi ascending light'
ning, had no good ground for their views. The question is so
important as to demand development.

Certain natural philosophers, as we have already explained,
make lightning to consist in a subtile matter, which darts with
the greatest rapidity from the body containing the lightning
to the body struck by it, whilst others regard it only as a vi-
bration. But, whichsoever of these hypotheses is adopted, the
direction of the propagation of the lightning, — in other words,
the direction of the propagation of the subtile matter, or of
the vibration, has hitherto been regarded as coinciding with that
of the mechanical effects produced by the matter, or by the im-
pulsion of the fluid. The lightning, it is alleged, which darts
from above downwards, should properly be called descending
lightning ; and, on the contrary, the name ascending lightning
should be appropriated to that which projects from below up-
wards, the substances it encounters in its course. Hence there
should also occur, if such there be, oblique and lateral light-
nings, in all directions. Facts which would go to the sup-
port of such distinctions are by no means rare, and we shall
now cite a few. On the 24th of February in the year 1774,
lightning struck the steeple of the village of Rouvroi, to the
north-west of Arras. One of its effects was the upraising of

ice, when it tears the capillary tubes which fonu the succulent twigs of cer-
tain plants. At the same time, as the aqueous juices dilate much more in pas-
sing from the liquid state to that of steam than they do in congealing, the me-
teor ought to produce more numerous and also more violent ruptures. By
taking this view of the phenomenon, physiologists will perlJaps be enabled to
recognise the particular mode of action by which lightning produces death
in the more common way.

112 On Ascending' Lightning.

the pavement, composed of large blue stones, placed under the
porch corresponding vertically to the weather-cock of the
steeple. In the summer of 1787 again, lightning fell upon
two individuals who had taken refuge under a tree, near the
village of Tacon, in the Beaujolois. Their hair was tossed
high up the tree, and a small ring of iron which was attached
to the shoe of one of these unfortunate individuals was also
found, after the event, hooked to a very high branch. On the
29th of August 1808, lightning fell upon a temporary erection,
of a round form, and covered with thatch, belonging to a pub-
lic house behind the hospital of Salpetriere at Paris. A work-
man who was sitting under this building was killed, and por-
tions of his hat were found sticking in the roof.

If all these phenomena of upraising be regarded as the di-
rect effects of lightning, it will appear difficult not to admit,
with the natural philosophers who have more particularly dwelt
upon them, that in the instances which occurred at Rouvroi,
Tacon, and la Salpetriere, it was ascending ; — that instead of
descending from the clouds to the earth, it was projected from
the earth towards the clouds. If, on the contrary, you admit
the possibility of indirect effects, and if you regard steam as in-
termediate, then the upraising of the pavement of Rouvroi, and
the projection from below upwards of the iron ring of Tacon,
and the fragments at the hotel of Salpetriere no longer assist in
indicating the direction of the moveipent of the Hghtning.

Flashes of lightning sometimes produce only the partial de-
cortication of trees. On these occasions it is not rare to find
long stripes of bark, both the outer coarse bark, and the inner
and finer membrane, completely detached heloiv, and still adher-
ing to the trunk near its summit. The old volumes ^of the
Academy of Sciences would furnish me, if required, with many
instances of this phenomenon. I might find them also in going
over Le Journal de Physique, and more especially the Memoir
of M. Mourgues concerning the storms observed at Marsillar-
gues, near Montpellier, in the month of June 1778 ; in a me-
moir of M. Marchais relative to the flashes of lightning which
struck a numlfer of trees in the Champs Elysees at Paris, &c.
&C. ; but all these instances of bark torn from below upwards,

Oji ascending Lightning, 113

no longer subserve the object for which they have been addu
ced, so soon as steam is considered as the possible agent by which
tlie process of decortication has been accomplished.

I may make precisely the same remarks concerning another
phenomenon which has been pointed out by observers with the
same assiduous care, and which relates to the leaves of those
trees that have been struck by lightning. The leaves of the
trees at Marsillargues upon the property of M. Mourgues, as
also the leaves of the trees in the Champs Elysees, which were
examined by M, Marchais, were yellow, crisp, as if roasted, and
convex on their under sides, whilst the green surface of the
opposite and upper side had not undergone any alteration, ex-
cepting only, that their planes, instead of being somewhat con-
vex, had become concave, precisely as happens on those sides of
sheets of parchment which are turned from the fire. Here, it is
maintained, another striking proof is afforded that the flaming
current of the lightning passed from below upwards. The
movement from beneath upwards seems, in truth, sufficiently
established ; but who will venture, in the present state of the
inquiry, to affirm that the ascending current was not produced
by steam at a high temperature, probably not saturated, and re-
sulting from the evaporation produced by the agency of a de^
scending Jlash ()/' UgJdning acting upon the humidity of the
soil ? Finally, we might have recourse to the same agency of
steam in explaining how, at the foot of trees that have been
struck, we often find the sod turned over, and sometimes opened
up at either side of the laceration of the soil, like the leaves of
an open book.

In thus prosecuting this minute discussion, I have endea-
voured to demonstrate that the facts, upon which many natural
philosophers believe that they have established the existence of
ascending lightning, do not confer upon their labours the cha-
racter of true demonstrations. I shall, however, moreover add,
that the question appears to me completely settled by the whole
of the circumstances of a melancholy event which took place
near Coldstream, in Scotland, and which are detailed in another
part of this essay. I unreservedly admit, then, the existence of
ascending lightnings, I know well that natural philosophers of
the highest character disbelieve in them ; I also know that they

VOL. XXVI. NO. LI. JANUARY 1839- ' H

114 Danger from Lightning,

disdain to enter into any discussion upon the subject ; but facts
should, and will prevail over the most imposing authorities.
"When Mqffei, now about a century ago, resolved to publish his
ideas upon ascending thunder-bolts, based upon a local pheno-
menon he had observed at the Castle of Fosdinovo, he had the
precaution, more prudent in this respect than Galileo to de-
monstrate that he could reconcile his views with the passages in
the Holy Scriptures, in which notice is taken oi Jire Jailing
from heaven on Sodom and Gomorrha, and of lightning de-
scending from the clouds, &c. Fortunately, in the present
day, the most celebrated scientific theories, though to some in-
dividuals objects of a religious veneration, do not require the
same kind of reserve. Every one may now examine them, and
may criticise and debate concerning them, and requires only to
stop where the field of observation and experiment is veiled from
his path.

UPON THE DANGERS WHICH ARISE FROM LIGHTNING, AND UPON THE
MEANS WHICH AT DIFFERENT TIMES HAVE BEEN USED FOR PRO-
TECTION, MORE ESPECIALLY CONDUCTORS.

Are the dangers which arise from lightning so considerable as to
merit consideration ?

Is the danger of being struck with lightning so great, that we
ought reasonably to attach importance to the means of guarding
against it .^ This question has different aspects, and it may be
regarded in reference to individuals, to dwellings, and to ships.

In the centre of the great towns of Europe, mankind, it would
at first glance appear, are but httie exposed. Lichtenberg says
that he had satisfied himself that during half a century^ Jive
men only were seriously struck with lightning in the town of Got-
tingen ; of these five, three only died. It is stated, with regard
to Halle, that a single individual had been killed by lightning
in the interval between the years 1609 and 1825, that is to say
in more than two centuries. At Paris, where tables concerning
the metropolitan welfare are kept with such regularity, the chief
officer of the Statistics of the Prefecture assured me that during
a great number of years not a single death had been notified as
produced by lightning. Notwithstanding this, however, there
were not wanting instances during the same period, and in the

Danger from Lightning. 115

department of the Seine, of individuals who had been so de-
stroyed ; thus there was the workman of whom we have recently
spoken at page 112, in connection with ascending lightning;
there was also an husbandman killed in the fields in the com-
mune of Champigny, on the 26th June 1807 ; and likewise a
mower killed at Romainville, on the 3d of August 1811, when
he was running for shelter with a pitchfork in his hand. Hence
it must have happened that the deaths from lightning were
designated and registered as deaths from accidents ; hence, too,
we should probably be much mistaken were we to receive as
accurate, and true to the letter, the number of deaths which
Lichtenberg reports for Gottingen and Halle. Nor would the
risk of error be less were we to generalize these results, by ap-
plying to all countries over the globe what had been observed
in one only, and in wishing to deduce from the experience of a
village what ought to be dreaded in a great city. Gottingen,
Halle, and Paris, it is said, scarcely reckon a single accident in
a century 1 True ; but let us notice what a little more accu-
rate investigation declares ; and, for this end, I open very much
at hazard, a few volumes in which I read such particulars as
the followino^ : —

On the night between the 26th and 27th of July 1759, a flash
of lightning struck the theatre of the town of Feltre. It
KILLED A GREAT NUMBER of tkose present, and more or less
wounded all the others * On the 18th of February 1770, a
single thunderbolt threw to the ground, without their know-
ledge, ALL the inhabitants of Keverne in Cornwall, who were
assembled in their parish church during their Sunday service.
In the year 1808, the lightning fell twice in rapid succession
upon the inn of the town of Capelle, in Breisgau, and hilled
four persons and wounded a great many more. On the 20th of
March 1784, the lightning struck the theatre at Mantua ; of
400 people who were present it killed two and zvounded ten.\
On the 11th of July 1819, the lightning fell during the service,

* Lightning often occasions extensive fires ; on this occasion it was the
reverse, for it put out all the lights.

t On this occasion, the lightning also melted ear-rings and watch-keys ;
it likewise cleaved diamonds, and this without wounding in the slightett de-
gree those who wore these several articles.

116 Danger from Lightning.

upon the church qfChdteauneuf-les-Moutiers^ in the neighbour-
hood of Digne, Department of the Lower Alps, and killed nine
individuals on the spot, and more or less wounded eighty-two.
The same flash killed in the middle of a stable, close to the
building, five sheep and a mare.

In spite of these citations, no one will doubt me when I affirm
that to each of the inhabitants of Paris, or any other city, the
danger of being struck with lightning is less than that of being
killed in the street by the fall of a workman from a roof, or of a
chimney-can, or flower-pot. There is no one, I believe, who,
in starting in the morning, dwells upon the idea that a work-
man, or chimney, or flower-pot, will fall on his head. If, then,
fear reasoned, we should not be more uneasy during a thunder-
storm which lasted for a whole day. For the acquittal of our
understandings, however, it ought to be added that the vivid and
sudden flashes which announce the lightning, and its resounding
thunders, produce involuntary nervous effects which the strongest
organizations cannot always resist. It ought also to be stated,
that if the descent of true thunderbolts is but rare, the total
number of strokes of lightning of one kind and another,
throughout the year is, on the contrar}^ very great ; that
nothing distinguishes the harmless flashes from the others ; and
that however insignificant in reality the danger may truly be,
it seems to be increased by the considerable number of its
apparent renewals. This consideration will appear clearer if,
returning to our term of comparison, I suppose that at the mo-
ment when a workman, or chimney, or flower-pot was about to
Jail from a roof or a window, a very loud detonation were to
announce the event throughout the whole extent of the city ;
every one might then conceive, many times a-day, that he was
precisely in the street where the accident was to happen, and
his alarm, without being at all better founded, would become
conceivable.

I have been treating above of the accidents which occur in
the middle of g7'eat toivns. Were we to rely upon general be-
lief there is much greater danger in villages, and in the open
country. Theoretical considerations to which the review I am
now taking forbids me to advert, would tend to confirm this
opinion. As for facts again, I see not how it is possible to

Danger from Lightupig, 117

invoke their aid, since they have been so very partially col-
lected. To this must be added that no accurate account has
been preserved of the drfferences which exist as to the frequency
and the intensity of thunder-storms, or to their occurrence in
different countries, or even in different circumscri!)ed spaces.

No one in the Republic of New Grenada willino^ly inhabits
El Sitio ds Tumha barrefo, near the golden mine of Vega de
Sztpia, on account of the frccjucncy of thunderbolts. The
people have preserved the recollection of a f]jreat number of
miners who had been killed by lightning. "While M. Bous-
singault traversed El SHio during the prevalence of a storm,
a flash of lightning struck to the ground a negro who was act-
ing as his guide. The Loma de Pitago, in the environs of
Popayan, possesses the same melancholy celebrity. A young
Swedish botanist, M. Plancheman^ obstinately persisting, not-
withstanding the advice of the inhabitants, to cross the Loma,
when the sky was covered with stormy looking clouds, there met
his death. Finally, in considering great countries only, it ap-
pears that in some, entire years occasionally elapse without a
word being said of the tragical events occasioned by lightning,
whilst in others, on the contrary, in certain seasons they seem
to happen almost daily. For example, I find that in the sum-
mer of 1797, from the month of June till the 18th of August,
Volney counted in the newspapers of the United States, eighty-
four serious accidents, and seventeen deaths ; whilst in France,
the newspapers of the year 1805, if I am rightly informed, only
announce one thunder-storm which was productive of the death
of one individual. In the year 180G, again, they recount only
the death of two children who were struck upon their mother's
knee at Auhagne, Department des Bouches du Rhone : in the year
1807, these same journals mention the case only of two young
])easants of the Comimme de St Geiiicz who were struck with
lightning when engaged in harvest-work ; and in 1808 they allude
only to a waterman who was killed on the banks of the river at
Angers. Notwithstanding all this, the years are very far, even
in France, from resembling each other, in respect of the num-
ber of deaths from lightning. In one year, 1819, the reported
victims are the following : — On the 28th of June, three horses,
near to Vitry-le-Fraricais ; on the lllh of July, as already

118 Danger from, Lightning.

stated, nine individuals in the church of Chdteauneuf; on the
26th of the same month, a man killed in the open fields at
Maxey sur Vaize (Meurthe) ; on the 27th, a husbandman, his
wife, and son, who had taken refuge in the portico of a chapel
near Chatillon sur Seine ; on the 1st of August Jbrti/f)icr sheep,
near Beaumout le Roger {Eure) ; on the 2d of the same month,
a labourer who had taken refuge under a tree at Bourdeaux ;
on the same day, a husbandman of Vignetix, near Savenay, who
was killed in his chamber ; and, still under the same date, two
young students and two girls, between ten and twelve years of
age, in the house of M. TAbbe Coyrier, at ... . De^
partement du Cantal ; and, finally, on the 27th of September at
five in the morning, a female domestic servant who was killed in
her bed, at Confolens, Charente.

But if few persons perish from thunder-storms in the heart of
our towns, the number of houses and edifices which are struck,
and seriously injured, is, on the contrary, very considerable.
During the single night from the l4th to the 15th of April 1718,
the lightning struck twenty-four steeples in the space compre-
hended along the coast of Brittany, between Landernau and
*S'^ Polrde-Leon. During the night between the 25th and 26th
of April 1760, the lightning fell three times, in the short in-
terval of twenty minutes, upon the chapel and other buildings
of the Abbey of the Notre-Dame-de-Ham. On the morning
of the 17th of September 1772, the lightning injured Jour dif-
ferent buildings at Padua. A memoir of Henley, which is
dated December 1773, informs us that the same day, nay, that
nearly at the same moment, the lightning over London struck
the steeple of St MichaePs, the obelisk in St George's Fields,
the New Bridewell, a house in Lambeth, another house near
Vauxhall, and a great number of other places very distant from
each other, not omitting^ a Dutch vessel which was lying at
anchor near the Tower.

A learned German found in the year 1783, that within the
space of thirty-three years, hghtning had struck 386 steeples,
and had killed 121 ringers* — the number of the wounded being

* These numbers will not astonish any one, if I mention that, on the lltli
of Jmie 1775, lightning fell upon the steeple of the village of Aubigny, and
killed at the same instant three men, who were ringing the bells, and four
children who had taken refuge under the tower of the same steeple.

1

Danger Jrom Lighiiiing, 119

of course much more considerable. In December 1806, du-
ring a single storm, the lightning destroyed, in whole or in
part, the steeples of St Martin at Vitre^ of Erbre, of Croisiltes,
and of Etrelles. On the 11th of July 1807, the steeple of St
Martin^ was again struck, and five days before the lightning
had fallen at la Guerche, and around that city, within the
space of a league in different directions, upon ten chapels and
other edifices. At Paris, on the night between the 7th and 8th
of August 1807, the lightning fell upon the sign-post of a shop
in the Rue de Tliionville, upon a house near la Halle, upon a
reflector of a lamp of the Rue de Perpignan, in the Rue aux
FSves, at Vaugirard, and at Pass?/. On the 14th May 1806, we
find it damaging a joiner's workshop in the Rue Caumartin ;
on the 26th June 1807, it injured nine portions of a house of
Aubervilliers ; on the 29th of August 1808, it struck a public-
house near the Barriere des Gobelins, and killed and wounded
many ; near the Barriere Mant-marire, it fell upon another
public-house filled with people, many of whom were knocked
down in a state of insensibility ; on the 14th of February 1809)
it knocked to pieces a wind-mill, situated on the road to St
Denis ; — on the 29th of June 1810, it did much damage to a
house in the Rue Aumaire ; — .next day it broke and scattered
about whatever it encountered in a house in the Rue Popeliniere ;
and on the 3d of August 181 1 , it fell upon a house at the Barriere
de Pantin, and wounded many individuals.

On the 11th of January 1815, during a thunder-storm which
embraced the space comprehended between the Northern Ocean
and the Rhenish provinces, the lightning fell upon twelve
steeples dispersed over this great extent of country, set fire to
many, and greatly injured others. In leaving this recapitula-
tion of recorded facts, it is scarcely necessary, I imagine, to re-
mark that I believe it very far indeed from being complete.
Every one indeed will recognise that it reaches only the mini-
mum limits of the subject.

The necessity there is for protecting buildings against light-
ning, should be measured by the number of those which are
annually struck by it, and also by the extent and importance of
the damage which it carries in its train. Three or four citations
will shew the importance of this last-mentioned consideration.

120 Danger to Powder Magazines.

In the year 1417, lightning set fire to the woodwork which
terminated the steeple of St Mark at Venice, and the whole was
consumed. This pyramid was reconstructed, but another thunder-
storm reduced it to ashes on the 12th of August 1489. On the
20th of May 1711, a single thunderbolt not only did very great
damage, both to the interior and the exterior of the principal
tower of the town of Berne.j but it also devastated nine houses
in its immediate neighbourhood. The pyramid of St Mark (on
this occasion it was built of stone) received a violent stroke of
lightning on the 23d of April 1745. The repairs of the damage
cost more than 8000 ducats. On the 27th of July 1759, the
lightning burned all the wood-work of the roof of the Cathedral
of Strasburg. In the month of October following, this meteor
struck the upper part of the magnificent tower of this same
town, and so completely divided one of the pillars which sup-
ported the lantern, that it was discussed at the time, whether it
should be taken down. The reparation of the damage cost
more thdiU three hundred tlious and francs . The three strokes
of lightning which, in the night from the 25th to the 26tli
of April 1760, struck the church of Notre-dame of Ham, led
to the burning and complete ruin of this great and beautiful
building.

In speaking of damage, I should not forget that which light-
ning sometimes occasions when it strikes poa^c?f:r magazines. On
the morning of the 18th of August 1769, lightning fell upon
the tower of St Nazaire at Brescia. This tower stood upon a
subterranean magazine, which contained 2,076,000 pounds of
powder belonging to the Republic of Venice. This immense
mass of powder ignited in a moment. The sixth part of the
edifices in the great and beautiful town of Brescia were over-
turned, and the rest were much shaken and threatened with
destruction. Three thousand persons perished. The tower of
St Nazaire was projected entire into the air, and fell down again
a shower of stones. Fragments of it were found at enormous
distances. The destruction of materials was rated at tivo mil-
lions of ducats.

On the 18th of August, lightning set fire to the powder which
was at the time in the magazine of Malaga. The building was
overturned ; and the whole town would assuredly have shared

Danger to Powder Magazines. 121

the same fate, had tliey not, some time previously, transported
the greatest part of the powder into more distant magazines.
On the 4th of May 1785, a thunderbolt set fire to the powder
magazine at Tangier. The magazine and most of the houses
in the neighbourhood were blown up. On the 26th June 1807,
at half past eleven in the forenoon, lightning blew up a pow-
der-magazine at Luxemburg, which was very solid, and long
before built upon a rock by the Spaniards ; it contained up-
wards of 28,000 pounds of powder. Thirty persons perished ;
more than 200 were mutilated or grievously wounded. The
lower town was a heap of ruins. At nearly the distance of a
league, very large stones of the magazine were found conveyed
thither by the explosion. On the 9th of September 1808,
lightning fell upon a magazine of military stores at the fort of
St Andrea-del-Lido at Venice, and blew it up. The explosion
completely destroyed a barrack, a neighbouring chapel, the wall
of a half-moon battery, greatly damaging, at the same time, the
barracks of the artillery.

I have multiplied these citations regarding the explosions of
powder-magazines, because, by a succession of qualifications,
some have been led to conclude, that even although lightning
penetrates these buildings, yet it never sets onfire the ammunition
they contain. Having shewn how completely untenable such a
proposition is, I am free to avow that in certain instances the
meteor has presented anomalies which wouW warrant almost any
hypothesis. Thus, on the 15th of November 1755, lightning
descended near Rouen, upon the powder-magazine of Maromme^
broke one of the rafters of the roof, and shattered to pieces two
casks which were full ()f powder without igniting it. The maga-
zine at the time contained 800 of these casks. Again, at day-
light, on the 11th of June 1775, the lightning struck the tower
of Saint Second at Venice, entered the magazine, threw down
the shelves, overturned the powder-cases, and, what appeared
quite miraculous at the time, set fire to none of it.

A list of a number of vessels, amounting to forty-two, which
have been struck with lightning, has been prepared, and is
printed in another part of this essay. At present we shall
only remark that after examining it, it seems quite superfluous

122 Danger to Ships Jrom Lightning.

to insist upon the utility of the means which have been made
available for the protection of ships against these dangers. This
list, however, which was prepared with a particular object,
contains only a small proportion of the names of the vessels it
might have included, if I had enumerated them without a state-
ment of their date and geographical position. Hence, in the
very restricted circle of my own information, I might add to
the list above alluded to the following : —

The (name unknown) an English merchant ship, was struck with light-
ning in the year 1675, near Bermuda.
The (idem) a merchant ship, was struck at Bencoolen, in the year 1741.
The (idem) a Dutch ship, was completely burned by lightning in 1746,

in the Roads of Batavia. When the fire reached the powder, the

ship blew up.
The (idem) a Dutch ship, was struck and much damaged in 1750, near

Malacca.
The Harriet, English packet, in sailing to New York in 1762. The whole

three masts were entirely destroyed.
La Modeste, French frigate, completely burned, in 1766, from lightning.
Captain Cook's vessel, and a Dutch ship, were both struck with lightning

in Batavia Roads.
Le Zephir, French frigate, struck at Port-au-Prince, St Domingo, 23d

September 1772 ; the top-mast was destroyed.
Le Meilleur Ami, of Bourdeaux, struck, same place, 25th May 1785 ; the

mizen and two top-masts shattered to pieces.
Le Prevost de Langristin, of Rochelle, struck, same place, 29th July

1785 ; two of the top-masts required to be replaced.
Le (name unknown), French schooner, struck, same place and day ;

main-mast destroyed.
The Duke, British 90 gun ship, struck, 1793, ofi* Martinico ; one of its

masts shattered.
The Gibraltar, British ship-of-the-line, struck, 1801, and much damaged.

immediately over the powder-room.
The Perseus, British vessel, struck at Port-Jackson, in October 1802 ;

the accidents led to the loss of the vessel.
The Desire, British frigate, struck at Jamaica, in 1803 ; one of the masts

much injured.
The Theseus, British vessel, struck, St Domingo, 1804.
The Favourite, British corvette, struck, Jamaica, June 1804 ; three sailors

killed, nine wounded, main-mast much damaged.
The Desire, British frigate, struck, near Jamaica, 20th August 1804;

many parts of the ship burned by the lightning.
The Glory, ship-of-the-line, in Admiral Calder's squadron, off Cape St

Finisterre ; the three masts were made useless.
The Repulse, British vessel, struck in the Bay of Rosas, in 1809.

Danger to Ships from Lightning, 123

The Dosdalus, British frigate, at Jamaica, in 1809 ; some of the crew

struck down, the lightning fired the powder.
The HehCj British frigate, at Jamaica, in 1809 ; one of the masts destroyed.
The (name unknown), British schooner, Jamaica, in 1809 ; sunk by the

same thunder-bolt as the two last.
The Glory, British ship-of-the-line, off Cape Finisterre, 1811 ; had all its

masts cleft.
The Norge, British ship-of-war, and a merchant vessel, Jamaica, June

1813 ; the Norge was dismasted.
The Palrria, British frigate. Harbour of Carthagena, S. A., in 1814; one

of its masts destroyed.
The Medusa, British brig, in its voyage from Guayra to Liverpool.
The Amphion, American vessel, sailing from New York to Rio Janeiro,

21st September 1822; much damaged, all its compasses destroyed.
The J^essg, of London, abandoned in 46° N. L. and 16° W. L., in Novem-
ber 1833, from the injury by lightning.
The Carron, British steamer, in passage from Greece to Malta, struck in

1834.

In running over such catalogues as these with attention, it is
remarkable, and such statements are truly striking, that in fifteen
months of the years 1829 and 1830, there were in the Mediter-
ranean alone, five ships of the British Royal Navy struck with
lightning. These were the Mosqttito of 10 gims, the Madagas-
car of 50, and the Ocean, Melville, and Gloucester ships-of-the-
line. All these vessels suffered considerably in the rigging. I
will add, for the benefit of those who imagine that the damage
arising from lightning is of small importance as a pecuniary-
matter, that a large lower mast of a frigate costs about L.200,
and the great lower mast of a ship-of-the-line costs as much as
L.400.

To all these authentic examples of the effects of lightning it
must be added, that the British ship Resistance of 44 guns,
and the Lynx^ completely disappeared during a severe thunder-
storm, in a convoy of which they formed a part ; that the ship
Yorh of 64 guns, which was never heard of after its entrance
into the Mediterranean, was probably blown up or sunk by this
same meteor ; and that the instances of burnings in the preced-
ing list, are by no means the only ones which might be enu-
merated. Thus, for example, the Logan of New York, of
420 tons and of L.20,000 value, was entirely consumed ; the
Hannibal of Boston shared the same fate in 1824. Moreover,

124 Means of Protection against Lightning.

the crews do not suffer less than the masts, the cordage, and the
hulks of ships. Thus there were tzvo men killed, and twenty-
two wounded by the thunderbolt, which, in the year 1799, struck
the Cambrian at Plymouth ; under the same circumstances, the
Sidtan, at Mahon, lost^z;^ men killed on the spot, two thrown
into the sea and drowned, and three more, severely burned ; nine
men perished on board the Repulse^ by the flash which struck
that vessel in the Bay of Rosas in 1809 ; and there were three
seamen killed, and Jive wounded on board the Austrian frigate
Leipsig, when she was struck on the coast of Cephalonia.
. The facts, however, which I have already reported, ought to
be sufficient. They have been cited without exaggeration, and
without concealment. Every one, therefore, may appreciate at
its true value the importance of the various methods which have
been proposed for preservation against lightning. It is now
time, then, to submit these to serious consideration.

ON THE MEANS OF PROTECTION AGAINST LIGHTNING.

I shall, I trust, be pardoned if I here briefly enumerate cer-
tain alleged means of preservation which, examined in the pre-
sent day with the light which the progress of science has sup-
plied, may appear somewhat absurd. At all events, it ought
not to be forgotten that the study of the aberrations of the
human mind ought not to be separated from that of true disco-
veries, for the greatest errors may probably still boast a host of
partisans.

On the means which Mankind have employed for personal protection
against Lightning.

Grecian literature has completely initiated us into the ideas
of the ancient philosophers regarding the causeof thunder; whilst
we find in their works only the most summary and imperfect
notices regarding two or three methods had recourse to for pre-
servation against its effects. Herodotus, in his 4th Book and
94th chapter, mentions " that the Thracians are in the habit
when it lightens or thunders, to shoot their arrows into the
sk^ to threaten it^ " To threaten it,''"' says the Greek au-
thor, a phrase worthy of remark ! It is by no means ques-
tioned, in the passage, that the arrow possessed a power,

Means of Protection against Lightning. 125

both as being metallic and pointed, whereby it could deprive
the clouds of some part of their fulminating material. Hence
Dutens himself, that wild admirer of antiquity, has heretofore
extended the idea of assimilating the Thracian arrows to the
modern conductors, and has traced the invention of Franklin'*s
apparatus as far back as the time of Herodotus.

Pliny states that the Etruscans were acquainted with the art
of making lightning descend from heaven ; that they directed
it at their will, and that they made it strike, among others, a
monster named VoUa who ravaged the Volsci ; that Numa had
the same secret ; and that Tullius Hostilius, not so accomplished
in the performance of the ceremonies borrowed from his prede-
cessor,' contrived by lightning to destroy himself. As to the
means of thus invoking this all-powerful agent, Pliny speaks
only of sacrifices, prayers, and such like, so that we may, with-
out more ado, advance with our subject.* The ancients be-
lieved (see Pliny, lib. ii. § 56) that the lightning never pene-
traied further into the earth than five Jeet, Hence the majority
of caverns were considered by them as perfectly secure asylums ;
and hence, according to Suetonius, no sooner was a thunder-
storm anticipated than the Emperor Augustus retired into a
low and vaulted retreat. The vitreous tubes which are produced
by the thunderbolt, and concerning whose origin, as we may
lake an opportunity of stating, there has so long been such di-
versity of opinion, and which sometimes penetrate the soil to
the depth of a hundred feet, conspicuously shew how thoroughly
the ancienls had deceived themselves on diis point. No one,
even at the present day, knows, and far less can state, at what
depth there is perfect security from descending lightning, and
still less from ascending.

With the purpose of adding to the guarantee, which results
from the thickness of a certain quantity of masonry, — of stone
or of earth, — with which a subterranean vault, or natural cavern.

* Is it true that there is now in existence a Roman medal which has
Jupiter Elicius as its legend, and represents tliis god soaring upon a cloud,
whilst an Etruscan is flying a paper-kite in the air ? Duchoul has engraved
a medal of Augustus, in which we see a temple of Juno, the goddess of
the air, the pinnacle of which is supplied with many pointed stakes. Is
this medal authentic ^.—{Labaissieref Acad, du Gard.)

126 Means of Protection against Lightning.

may be covered, the emperors of Japan, if Koempfer may be
credited, cause a reservoir of water to be established above the
grotto in which they are wont to -take refuge during thunder-
storms ; the water being destined to extinguish lightning. In
certain circumstances, which we must ere long point out, a sheet
of water does become a preservative, almost certain, for what-
ever is placed beneath it ; but from this fact, it is not to be in-
ferred, that fish may not be destroyed by lightning throughout
the wide extent of their liquid habitation. Weichard Valvasor
informs us, in the 16th volume of the Philosophical Transac-
tions, that lightning, in the year 1670, having fallen on the
lake of Zirknitz, such a quantity of fish almost immediately
floated upon the surface, that the neighbouring inhabitants col-
lected twenty-eight waggon-load for manure. Again, on the
24th of September 1 772, lightning descended at Besanfon, in
the Doubs, and immediately the surface of the water was co-
vered with stunned fish, which were floated along by the cur-
rent of the stream.

In days now gone by, it was generally thought, that indivi-
duals who ensconced themselves in their beds, had nothing to fear
Jrom lightning. This opinion, however extraordinary, seems
still to have partisans. Thus, for example, I find that Mr Howard
has taken particular care to register the two following facts :
On the 3d of July 1828, a cottage at Birdham, near Chichester,
was struck by lightning. With a crash, it destroyed the wooden
part of a bed, threw the bed-clothes on the ground, the mattress
likewise, and the individual who reposed upon it, without inflict'
ing upon him the slightest injury. Again, on the 9th of the
same month, at Great-Hough ton, near Doncaster, lightning re-
moved the coverlit of a bed on which a Mrs Brook was lying,
and she was no further annoyed than by her fears. But, to such
facts as these, it is no difficult matter to oppose others which
are not less authentic. In the 63d volume of the Philosophical
Transactions, there is a memoir, in which a clergyman, Mr
Samuel Kirkshaw, gives an account of the particulars of a
flash of lightning surprising Mr Thomas Hearthlcy, while
asleep in his bed, at Harrowgate, on the 29th of September
1772, and killing him on the spot. Mrs Hearthley, sleeping
by her husband, was not even awakened by it. She complained

Means of Protection against Lightning. 127

of pain in her right arm, which, however, only lasted a few
hours.

TJie sJcin of the seal was considered by the Romans as an
efficacious preservative against lightning. On this account tents
were manufactured of these skins, to which the timid resorted
during a thunder-storm. Suetonius mentions, that the Em-
peror Augustus, who was afraid of thunder, always carried one
of these skins with him. In the Cevennes (Depart, du Gard),
where Roman colonies for so long existed, the shepherds collected
the cast skins q/' serpents, with the greatest care ; as late even
as our own times, they surrounded the crowns of their hats
with them, and supposed that then they were safe from light-
ning (Laboissiere, Acad, du Gard). These serpents' skins, to
all appearance, formerly served the same purpose, in the esti-
mation of the people, as the rarer and more valuable seals'
skins had previously done.

It is the more expedient thus to dwell upon the selection
which Augustus made of the skin of seals, as at present we do
not know how to justify it, either by fgcts or theory. As re-
spects, however, the idea, that the choice of clothing is not
wholly a matter of indifference under a thunder-storm, the in-
formation of the moderns concerning the fulminating matter, in
no degree contradicts it. On the other hand, numerous in-
stances may even be cited, in which it would seem, that some
individuals appear to have been preserved, and others struck,
according as they wore particular garments, manufactured of
particular stuffs. Thus, on the day of the catastrophe, at the
Chdteauneiif-les-Moutiers already alluded to, two of the three
priests who were officiating at the altar, were violently laid
prostrate, whilst the third sustained no injury; and he alone
was clothed in garments of silk.*

* According to indirect experiments, on which we shall dwell at a future
time, all natural philosophers have agreed, that wax-cloths, and silk and
woollen-stuffs are less permeable to the material of lightning than linen,
hempen-cloths, or other vegetable substances. They are not quite so well
agreed as to whether, in time of a storm, wet clothing is preferable to dry.
Nollett dreads wet clothing, because water communicates to them the
faculty with which it is itself endowed ; it being one of those bodies for
which lightning has a preference. Franklin again, adopts the opposite

128 Means of Protection against Lightning.

But there are facts still more astonishing, for it would ap-
pear that animals may be more or less severely injured in dif-
ferent parts of the body, according to the colour of the hair
which covers them. Thus, at the beginning of September 1774,
an ox was struck with lightning at Swanborrow, in Sussex.
The colour of this animal was red, spotted with white. After
it was struck, all were surprised to observe the denudation of
the white spots ; on these not a single hair remained, whilst the
red portions of the hide had not undergone any apparent altera-
tion. The owner of the animal stated, moreover, to Mr James
Lambert, that two years previously, another ox, under the
same circumstances, had exhibited precisely the same appear-
ances. Finally, on the SOth of September 1775, a pie-bald
horse having being struck with lightning, at Glynd, its owner
remarked, that, throughout the whole extent of the white spots,
the hair came oft', as it were, of itself, whilst, in the other parts,
the coat adhered as usual.

" When a thunder-storm threatened, Tiberius never failed to
wear a crown of laurel-leaves, under the idea that lightning
never touched the leaves of this tree." (Suetonius.) And the
opinion, that certain trees are never struck by the meteor, is
still widely spread. Mr Hugh Maxwell communicated to the
American Academy, in 1787, information, that, according to his
own observation, and the intelligence he had received from a
great number of individuals, he thought himself warranted in
affirming, that lightning often struck the elm, the chesnul, the
oak, and pine, and sometimes too the ash ; and that it never
fell upon the beach, the birch, and the maple. Captain Dib-
den does not allow such marked distinctions. In a letter to
Mr Wilsen, dated 1764, he only says, that in the forests of
Virginia, which he had visited, in the year 1763, the pines,
though considerably higher than the oaks, were not so frequently
struck as these last named ; and he adds, I do not remember,
in those localities where the oak and pine grew together, to
have seen the latter scathed by lightning. Let us now, how-
ever, inquire what facts declare upon the point.

opinion, under the idea that wet clothes must immediately transmit to the
soil the lightning which would otherwise strike the person.

Lightning as connected with Trees. 129

The ancients believed, that lightning never fell upon the
laurel. But never is not the proper expression; for I find,
in M. Poinsinet-de-Sivry's Notes, to his Translation of Pliny,
that Sinnertus, Vicomercatus, and Philip James Sachs, report
the destruction of these shrubs by lightning. Mr Maxwell
ranges the beech among the trees which are respected by light-
ning. A pamphlet, which M. H^ricart lately distributed to
the members of L? Academic des Sciences^ states, that an aged
beech, which had been preserved in the year 1835, among some
old trees which had been cut down in the middle of the forest
of Villers-Cotterets, was struck with lightning, and nearly de-
molished, in the month of July of the same year. Theoretical
considerations had induced a belief, that resinous trees were not
liable to injury from lightning. We have just seen, however,
that Mr Maxwell places the pine among those which are most
frequently struck. In the pamphlet of M. de Thury, I have
found enumerated, among the trees injured by lightning, the
following: — -A pine, at Samt-Martin-de-Thury^ in August
1834; a fir-tree, at Saint Jean-de-Day (Manche), in June
1836; a cherry-tree, Sit Anthilly^ in August 1834; an acacia,
at Saint-Jean-le-Pauvre-de-Thury, in September 1814 ; an elm,
at Moiselles, in June 1823 ; and oaks and poplars in abun-
dance.

Individuals are often struck with lightning in a free and
open country. Many facts, however, attest that the danger is
still greater under trees. Hence Dr Winthorpe concludes,
from this twofold remark, that to escape the effect of the meteor,
when surprised in the country, nothing better can be done,
than to place one's self at a little distance from some tall tree ;
by a little distance, understanding between sixteen and forty
feet. A station still more favourable would be found in a spot
which would satisfy those conditions, in regard to two or more
neighbouring trees. Franklin added the weight of his opinion
to the utility of those directions. Henley, who also con-
ceived that they were based both on theory and experience,
modified them only thus far, that when there was only a single
tree, individuals should be recommended to place themselves in
relation to its trunk from sixteen to twenty feet beyond a

VOL. XXVI. NO. LI.— JANUARY 1839- I

130 Lightning connected with Glass and Metals.

perpendicular line let fall from the extremity of its longest
branches.

Influenced by the consideration of certain analogies, natural
philosophers generally admit that lightning always respects
glass. Starting from this postulate, there is only a single step
to the conclusion that a chamber wholly constructed of glass
would be a perfectly secure refuge. Hence chambers or cases
have been proposed, and actually constructed for the use of
those who are apt to be overwhelmed with panic during a thun-
der storm. Though unquestionably disposed to grant that
under the circumstances an envelope made of glass may some-
what diminish the apprehended danger, yet I cannot admit
that it wholly removes it. And my reasons are these. The
great thunder-storm which injured the palace of Minuzzi, in
the territory of Ceneda on the 15th of June 1776, pierced or
h?vJi:e more than 800 panes of glass. Again, when Mr James
Adair was prostrated, in September 1780, by a violent stroke
of lightning, which killed two of his servants in his house at
Eastbourne, he was standing behind a glass window. On that
occasion the window-case was not at all injured, whilst all the
glass had completely disappeared, the lightning having reduced
it to powder.

Some, perhaps, may conclude that the rupture of glass on
guch occasions as these is the consequence of the violent con-
cussion of the air — a simple effect of the noise and detonation.
There are not, however, wanting facts which set aside this hy-
pothesis. On the 17th of September 17752 the lightning which
fell at Padua on a house in the Prato della Valle, pierced a
pane in a window on the ground-floor with a clean and rotmd
hole^ precisely such as a gimlet would make in a board. Again,
Caseli, the engineer of Alexandria, observed upon the glass of
his windows immediately after a flash of lightning, in the year
1778, a number of small round apertures with scarcely any ad-
jacent fissures. Once more, in September 1824, a thunder-bolt
having fallen on the house of Mr Wm. Brenmer at Milton
Comage, one of the panes of the window was found pierced by
a circidar hole of the size of a musTcet hall ; in the other parts
of the pane there was not a single crack or fissure. A perfectly
circular hole of this sort without fissures, cannot be the conse-

Lightning connected with Glass and Metals. 181

quence of agitation arising from sound. It might well be cited
as a proof of the extreme velocity of the lightning^s flash. The
aperture just described corroborates the other observations of a
somewhat similar nature reported as having occurred at Padua
and at AU^xandria. These observations united will undeceive
these individuals who imagine that glass plates are a complete
safe-guard against lightning.

Innumerable examples shew that lightning never strikes
individuals, without more particularly attacking any metals
they may happen to have about their persons. It may, there-
fore, be admitted that such objects sensibly increase the dan-
ger of being struck. None Vill deny this conclusion if the
question refers to any considerable mass of metal ; as is well
illustrated by the following incidents. On the 21st July 1819,
lightning fell upon the prison of Biberach (Suabia), and there
struck,, in the common apartment, in the midst of twenty priso-
ners, ONE condemned captain of brigands, who was chained
roimd the waist. The opinion is attended with more difficulty
in reference to those trifling metallic articles which often form a
part of our common dress. However, the following curious
observations made by Saussure and his companions on iheBreven,
in the year 1767, might be ranked as a proof on the point.
During a thunder-storm, whenever any of the party raised his
arm and extended a finger, he felt a pricking sensation at its
point. "M. Jalabert," adds the celebrated traveller, *< who
had a gold band round his cap, heard, in addition, a|frightful
buzzing noise round his head. We drew sparks of light from
the golden button of the band^ as also from a metallic ring which
surrounded a large stick we carried with us."" Confer the most
trifling additional intensity upon the storm, and the small gold
band, and its metallic button, in such circumstances as those
we are now contemplating on ihe^rcven^ will become the causes
of explosion, and M. Jalabert would have been injured by
lightning rather than his companions, whose hats were free from
golden bands and metallic buttons.

The following fact, mentioned by Constantini in the year
1749, bears directly on the point. During the prevalence of a
thunder-storm, a lady raised her arm to shut a window, — the
lightning flashed, and her golden bracelet so completely disap-

182 Lightning connected with Metals,

peared that no vestige of it could subsequently be found.
Otherwise, the lady received only the slightest possi"ble injuries.

Without such preliminary remarks as these, it might excite
astonishment that I should place here the explanation which
the celebrated traveller Brydone gives of a circumstance which
happened to Mrs Douglas, a lady of his acquaintance. This lady
was regarding a thunder-storm from her window. It light-
ened, and her hat, and her hat only, was reduced to ashes. Ac-
cording to Brydone, the lightning had been attracted by the
metalHc wire which maintained the shape of her bonnet and sup-
ported its softer materials. Hence he proposes that these wires
should be abandoned, and protests against the prevailing fashion
of maintaining the tresses and ornamenting the hair with gold
and silver pins.* And in the very natural apprehension that
this advice would be disregarded, he urges, " that every lady
should wear a small chain or thread of brass wire which she
should hang, during the time of a thunder-storm, to the wires
of her bonnet, by which the fulminating matter might pass to
the earth, instead of traversing the head and other members."*'

Upon the whole, it is preferable during a thunder storm to
have no metal about one. But is it, it may be asked, of the
slightest consequence to regard the increase of danger which a
watch, or buckles, or the money of your purse, or which the
wires, and chains, and pins used in a lady's toilet produce ? To
this question no general answer can be given ; for every one
will regard it through his own prepossessions, and will, more or
less, be determined by the apprehensions with which the meteor
inspires him.

When lightning falls upon man or animals, placed near each other,
whether in a straight line, or in an uninclosed curve, it is gene-
rally at the two extremities of the line that its effects are most in'
tense and hurtful.

This theorem, if I may so call it, seems to follow from the
facts which I have collected, and which subsequently may be
detailed ; in the mean while, I shall say a few words only, in the

* Kundman mentions that a flash of lightning melted a pin of copper
which retained the tresses of a young lady ; and adds, by way of parenthe-
sis, that the tresses were not singed.

witJi Files nfMen, or AmmaU. 133

way of analysis. It will here, I trust, be understood that 1 am
treating this subject simply as a question of science, and that
whilst I indicate the place where one is least exposed, I do not
advise every one to go and take refuge there, since, by thus di-
minishing his own risk, he inevitably augments that of his neigh-
bour. On the 2d of August 1785, the lightning descended upon
a stable at Rambouillet, where there were thirty-two horses in a
single continuous line. Thirty were overturned by the stroke.
One only, hozcever^ was instantly and quite killed ; it occupied
one of the extremities of the line ; and another, which was very
severely wounded, and subsequently died, was placed at the other
extremity. Again, on the 2J^d of August 1 808, lightning struck
a house, in the village of Knonau, in Switzerland. Five chil-
dren were sitting upon a bench, in a room on the ground floor;
of these the first and the last were killed dead on the spot,
whilst the others experienced only a violent shock. At Fla-
vigny, Cote d*or, five horses were in a stable into which light-
ning entered. The two first, and two last perished, — the fifth,
in the middle, suffered no injury.* One of my friends informs
me, that he was told, some years ago, and within a few days of
the event, that in a town of Franche Comte, the lightning having
fallen upon a file of five horses, in the open air, killed the first
and the last, whilst the three others were not even wounded.t
When lightning encounters a bar of metal, every one knows

* I adduce this fact, in support of tlie proposition at tlie commencement
of this. paragraph ; though, at the period of the event, it was supj)osed at
riavigny, that the whole was exphiined by the animal which escaped being-
Ulnd, whilst the others saw.

t In the year 1801, the lightning fell on a windmill, at Praville, near
(Jhartres, set it on fire, and consumed it. At the moment, the miller was
walking between a horse and a mule, which were both laden with corn. The
two animals, struck at the same instant, were killed on the spot ; the miller
escaped, with being fearfully stunned, with having some ringlets of his hair
burnt, and with the loss of his hat.

I have not introduced this instance into the text, because it does not ap-
])car so demonstrative as the others; — because it is not self-evident that
lightning, with equal facility, kills all kinds of animals ; and because, on
the contrary, it appears to be established by certain facts, that men
more powerfully resist the effects of lightning, than horses and dogs. I
shall here adduce some of the facts upon which I base this conclusion.

134 Preventive Measures against Lightning,

and comprehends, that it does not produce much apparent da-
mage, except at the spots where it made its entrance and its
exit. It may readily be supposed, that it is the same also
with bodies of a different nature ; but how this rule can extend
to instances in which there are considerable interruptions of conti-
nuity, does not so readily appear. How it happens then, that
thirty horses^ placed as horses usually are in a stable, should
be considered, so far as the effects of lightning are concerned,
as a single continued mass, having a beginning and an end, will
probably surpass the comprehension of every one. It is difficult,
however, to have recourse to any other analogy to account for
the curious phenomenon which has last been brought under re-
view.

Franklin has given directions for the use of those persons, who
being alarmed at lightning, are in houses unprotected by light-
ning-conductors, at the time of a thunder-storm. He advises
them to avoid the neighbourhood of chimneys ; and this, be-
cause lightning often enters into rooms by them, because the
soot they contain, like metals, possesses properties which at-
tracts lightning. For this same reason, a person should move
as far as possible from metals, and from mirrors, on account
of their tin-plates, and from gilded articles. The best resort
seems to be the middle of the apartment, provided there is no
lustre or lamp suspended from the ceiling. The less that one
touches the walls and the floor, the less are they exposed ;
and hence the safest of all expedients would be to retire into a
hammock, suspended by silken cords, in the centre of a large

On the 12th of April 1781, MM, d'Aussac, de Gautran, and de LamUongucj
were struck with lightning near Castres. The three horses which these
gentlemen rode, were killed, whilst only one of the gentlemen, M. d'Aussac,
became its victim. In June 1826, a flash of lightning killed a mare near
Worcester, whilst the boy, who was leading it, experienced no serious
injury. In June 1810, when M. Co wens' dog was sitting by his side,
lightning entered his apartment, and killed the dog on the spot, whilst
M. C. himself was scarcely conscious of any shock. As already reported,
the lightning, on the 11th of July 1819, killed nine persons during divine
service, at Chateau-Neuf-les-Moutiers ; we have still to add, that at the
same time, all the dogs in the building were killed ; and these animals
were found in the very attitudes they had occupied at the time of the de-
scent of the meteor.

Preventive Measures against Lightning. 185

chamber. When this suspension cannot be obtained, it is ex-
pedient to interpose between one's self, and the floor, some of
those bodies which the fulminating matter traverses with the
greatest difficulty. Accordingly, a chair may be placed on
glass, or pitch, or on mattresses. These precautions have a
direct tendency to diminish the danger, but they do not wholly
remove it. In fact, there are examples, of glass, pitch, and
many and thick mattresses having b^en traversed by lightning.
Besides, it ought not to be forgotten, that if the lightning does
not encounter, in the chamber, a wire-bell, which will lead
it out, it may dart from one point to another diametrically op-
posite, and in its course, may strike individuals in the centre,
and even suspended in their hammocks.

Meteorologists, and among others M. Balitoro, assert, that
lightning never strikes buildings upon their northern fronts ;
and according to them, it is on south-east exposures that it is most
of all to be dreaded. This opinion, it is stated, is so generally pre-
valent in Italy, that during a thunder-storm, many people take
the precaution of seeking refuge in those chambers of their house
which have a northern exposure. If this observation be truly
accurate, it is probably a consequence of the direction according
to which, in our climates, the wind almost always blows during a
thunder-storm. Clouds coming from the ^om^^, and highly im-
pregnated with fulminating matter, can scarcely fail to part with
it in preference, on*the first front of the edifices they encounter.
Besides, since it has been estabhshed, that the highly elevated
jets of the aurora-borealis range themselves in a direction paral-
lel to the inclination of the magnetic needle, we have no right to
deny the possibility of a similar, or common direction, to ful-
minating rays.

According to Nollet, the height and, all other circumstances
being equal, the roofs of those belfries which are covered with
slates, are more frequently severely injured by lightning than
such as are built of stone. We are not, I imagine, to look for
the cause of this peculiarity in any specific difference of the ma-
terial of which slate and the stones in question are composed.
It seems to be dependent rather upon the facility with which
during rain, the wood- work, and more especially the planks on

136 Lightning in relation to Crowds

which the slates rest, become moist, and upon the great number
of iron nails which are required to fasten them.

The more that any material possessed of conducting powers
is accumulated, whether in volume or weight, the greater, it
would appear, is the danger of the lightning inflicting injury
in the immediate vicinity. This being once admitted, since
living men are excellent conductors of the fulminating mat-
ter, the opinion of some able natural philosophers, and of M.
Nollet among others, should not be rejected, that the danger
of being struck in a church is augmented with the number
of individuals who are assembled. There is also another cause
which may contribute to make numerous assemblies of men and
of animals more dangerous during a thunder-storm. It is this,
their perspiration cannot fail to produce an ascending column of
vapour ; and every one knows that moist air is a much better
conductor of lightning than dry air ; and the column of air must
in preference conduct the lightning to the source whence it ema-
nates. We ought not, then, to be surprised that flocks of she^j
are so often injured, and that a single flash not unfrequently
destroys as many as thirty, forty, and even fifty of the flock.

In America, it is an opinion very generally entertained, that
hams filled with grain or forage are more liable to be struck
than other kinds of buildings. This fact should probably also
be referred to an ascending current of moist air, whose origin
may be traced to the circumstance that thfe harvest is usually
housed before it has become thoroughly dried.

A single person is sometimes struck in the midst of a nu-
merous group, without our being able to detect anything like
a determinate cause for this kind of selection, without his ha-
ving a greater quantity of metal about his person, or his ^osi-
iion appearing to be less favourable than that of his neighbours.
I say appearing less favourable, for a cause though invisible
may still be very active. Thus, a piece of iron for example,
enclosed in thick masonry, will act not less powerfully than if it
were exposed. Hence, it will but seldom occur that we can
• affirm that the positions, of the person struck and the person
spared, were in every respect identical ; for the latter may have
been further removed than the former from some hidden mass
pf metal, or some stream of water, or some other conductor hid

and to Individuals. 137

under a floor, or behind a wainscoat, or beneath the ground,
even without its ever being suspected. It seems, therefore,
difficult in this way to recognise with certainty, whether there
be a difference between man and man, as to their Hability
of being struck with lightning. The question can only be an-
swered by having recourse to indirect experiments ; and here,
though somewhat anticipating, we may introduce a very few
facts. The matter which is emitted in sparks from the conduc-
tor of an electrial machine when worked, is the matter of light-
ning. Like common lightning, therefore, it is transmitted, almost
without loss of power, through a great extent of metal, water, &c.
It thus also freely traverses a long- line of men, hand in hand,
thus forming a chain. But notwithstanding, there arc persons
who decidedly avert the communication, and who are not con-
scious even of the shock, although they may be placed second
on the line. These individuals, then, are exceptions, — they are
not conductors of the fulminating matter. In virtue, then, of
this exception, they must be ranged among non-conducting"
bodies which the lightning respects, or which it, at least, strikes
less frequently.

But such striking differences as these cannot exist, without
there being at the same time many shades of individual differ-
ences. Now, every degree of conductibility corresponds, during
the time of a thunder-storm, to a certain measure of danger.
An individual who is as good a conductor as metal, will be as
often struck as metal, and an individual who interrupts the
communication in t?ie chain above alluded to, will have scarcely
more to fear tjian if he were glass or resin. Between these
limits there will be individuals whom the lightning will have a
tendency to strike in the same degree as it strikes wood, stone,
&c., &c. Hence, regarding the phenomena of lightning, every
thing does not depend upon the place which a man, occupies,
something also depends upon the physical constitution of the
individual. And hence I affirm there are such specific differ-
ences, that during a thunder storm, in situations which are in
every respect alike, one person runs much more danger than
another.

138 Of' Running during a Thunder-Storm,

Is the risk of being struck increased by running, during a thunder-

storm f

It is stated to be dangerous to run on foot, or to ride rapidly
on horseback, during the time of a thunder-storm; and it is even
asserted that we should not walk against the wind, and in a direc-
tion contrary to the course of clouds. When these two opinions
are closely examined, they come to this, that it is expedient to
avoid being in a current of air. Does a current of air then really
attract lightning, in other words, does it facilitate its descent ? In
default of direct methods of resolving this question, the common
practice of shutting down the windows of our houses at the com-
mencement of a thunder-storm, has been adduced as the result
of unexceptionable experience ; and it has been argued, that so
many people, so widely separated from each other, would not have
agreed in shutting all close, unless this practice had been found
advantageous. Here it is scarcely necessary to remark, that a
popular prejudice in no degree warrants us to draw such a deduc-
tion. But besides, it both rains and blows hard during a thunder-
storm ; and the custom of closing doors and windows much more
naturally arises from the desire to guard against rain and
wind. It is also true, that, in some countries, the practice is
supported upon grounds that are altogether superstitious. Thus,
in the Russian province of Esthonia, for example, it is the fear
of leaving an entrance for the evil spirit whom God is pursuing^
during a thunder-storm which leads to the stuffing the smallest
crevice of the house. (Salverte, Des Sciences Occultes.) It is
somewhat remarkable, that their religious ideas have led the
Jews, in some countries, to act in a manner directly the reverse
of the Esthonians. As soon as lightning flashes in the sky, says
the Abbe Deehman, the Jews open their doors and windows,
that their expected Messiah, whose coming they anticipate with
thunder, may freely enter whithersoever he pleases.

We may now examine the custom above alluded to, so far as
the present state of science will allow us. The atmosphere op-
poses a certain degree of resistance to the passage of the fulmi-
nating matter. It is probable that that resistance diminishes when
the temperature and humidity increase, and when the barometer

Of Running during a Thunder-Storm. 139

I is low. Thus, whatever diminishes the density of the air to a
certain point, tends, more or less, to attract lightning. Now, a
man who runs in a calm, leaves a space behind him in which the
strokes of lightning will find readier transmission. I here add a
fact, the circumstances of which have been communicated to me
by my illustrious fellow member, Admiral Roussin, and which,
perhaps, will be considered as somewhat favourable to the con-
jectures we have been making. The frigate La Junoriy on her
way to India, was assailed on the 18th of April 1830, near the
Canaries, by a violent thunder-storm, during which, in spite of
her conducting-rod, she was struck with lightning. The fact of
her being so struck appears no ways doubtful. In fact, im-
mediately after the flash, there was a strong smell of sulphur all
over the vessel. Besides, those who were on the quarter-deck
saw a stream of light fly off^ from the conductor. This stream or
flash was seen at a point situated half-way between the {grand*
hune and the hartingage) top-gallant-mast and the halyards, and
fell into the sea to the larboard, whilst the extremity of the
conductor-chain led the sea on the other side, or to starboard.
I may here add, that at the moment of the flash, one of the
sailors was completely asphyxiated, and for a time was supposed
to be dead. After the accident, it was found upon examination
that the chain, composed of copper-wire, twisted like common
cordage, and forming a cylinder of about f ths of an inch iu dia-
meter, had not been fractured in any part. The point only of
the metallic vein, screwed to the top of the mast, and with which
the conducting chain was in communication, was somewhat burnt.
The fact of the lateral discharge of the lightning, darting from
the conductor, is completely established by all these details; but
we have still to discover the explanation. The first method of
accounting for it which occurs to the mind, is, that the metallic
chain was of much too small diameter. It adds force to this ob-
jection, if we moreover suppose, that at the moment of the flash
the lower extremity of the chain was not really under water.
This extremity was attached to a sheet of copper, usually fixed
about a couple of feet below the ship'*s water-mark. On the oc-
casion of this thunder-storm the copper sheet was starboard ; so
was the wind ; and it is stated to have been very strong. All these
circumstances lead to the supposition that the vessel must have

140 Of Traversing Thunder-Clouds,

been heeling greatly to the other side, and hence the end of the
chain must necessarily have been elevated out of the water ; un-
fortunately we cannot say y)recisely how much, and this circum-
stance weakens considerably the force of the conjecture.

On board La Junon, every one was convinced that the light-
ning quitted the conductor, because of the very violent wind
which was hloxving at the moment. I have no intention in the
world, of supporting this explanation ; whilst, on the other
hand, I will not be so bold as to maintain it is not worthy of ex-
amination. Behind the conducting chain, as behind the cord-
age, masts, &c., there must have been, in virtue of an hydraulic
phenomenon, well known under the name of the lateral commu-
nication of motion, a sort of void, in other words, a small space
in which the atmospheric pressure was considerably weakened.
Now, without hesitation to deny all influence to this decided di-
minution of pressure, would not be in the spirit of philosophy,
and especially in connection with so many physical observations,
which will ere long be detailed, when we compare the phenome-
na of artificial electricity with those of lightning.

Thus have we considered the various data upon which we may
be advised not to run, when in immediate danger from a thun-
der-storm. And now the inquiry remains, whether, in the cir-
cumstances, the diminution of the risk, by remaining motionless,
or walking gently, is a sufficient compensation for the annoyance
of being thoroughly drenched by the pelting shower.

Are the clouds tvhence thunder and lightning are incessantly issuing^
so constituted, as some natural philosophers suppose, that it is very
, dangerous to traverse them ?

The intimate constitution of clouds is too imperfectly known
to enable us to appreciate, from theoretic considerations alone,
the danger which would be incurred by approaching too near to
the centre and focus of a thunder-storm. Upon this point, the
general opinion appears to me rather a matter of feeling than the
result of any serious discussion. Those high black clouds often
hurl destruction, and burning, and death, from a distance !
What, then, would they not do were you near ? Volta himself
had probably no other guide than this general feeling, when in

Of Traversing Thunder-Clouds. 141

his memoir concerning the formation of hail, he characterized
the project of traversing a thunder-cloud as fool-hardiness.
However this may be, the question appears to me to merit
examination. It appears important to know if meteorologists
may cherish the hope of going, sooner or later, to study the
thunderbolt in the spot where it is elaborated. It is also of
importance, that we should be able accurately to value the real
amount of danger we are exposed to in certain mountains where
thunder-storms arise so rapidly that it is impossible for the tra-
veller to escape them. In the mean while, my task will be
confined to the investigation, whether individuals have ever been
found affected by the lightning of a decided thunder-storm
without being killed by it. And here I shall avail myself only
of such observations as are clear, precise, and free from ambi-
guity. All these characters are admirably combined in an ac-
count of the Abbe Richard* author of the " Histoire de VAhy
et des Meteores.

Towards the end of August 1750, this gentleman ascended
in his carriage the small mountain of Boyer^ at a short distance
from Senecey^ between Chdhns-sur-Saone^ and Toumus. At
about three-quarters of the height of the mountain, a cloud was
suspended in which the thunder rolled from time to time.
Speedily M. Richards reached it. From that moment the thun-
der no longer was heard in sharp peals with intervals of silence ;
but it made a continual noise " similar to the rolling of a heap of
nuts upon wooden planks." At the top of the mountain the ob-
server found himself above the cloud. Nor had the storm ceased
now ; for the lightning again flashed brightly, and loud peals
of thunder followed.

The second instance, which I proceed to cite, has not the
guarantee of coming from a natural philosopher, and in some re-
spects is on this account preferable, as the circumstances, few
and simple, were collected by an individual who had no sys-
tem to support. I write the following lines at the dictation
of my sister. " Some years ago I set off in the morning, with
two of my friends, from the village of Estagel to go to Limoux.
Our carriage had already accomplished a considerable part of
the winding and rapidly ascending road of the Col-Saint Louis,
when the whole valley suddenly became covered with stormy
clouds, concerning whose nature no one could mistake, since they

142 Of Traversing Thunder 'Clouds.

were ever and anoa illuminated with brilliant flashes of light-
ning, followed with loud peals of thuhder. My companions, as
well as I, wished to return ; but our conductor was of a diffe-
rent mind, and proceeded boldly forward to meet the storm. As
we were very much alarmed, we shut our eyes that we might not
see the lightning, and closed our ears that we might not hear the
thunder. We had continued in this state for about a quarter of
an hour, when the coachman informed us, to our unspeakable
gratification, that all danger was passed. The cloud, in truth,
was now under us; where it still continued to thunder and light-
en, but without disturbing our equanimity, for we were now
enjoying a pure sky, and a beautiful sun.

During their excursions in the Pyrenees, Captains Peytier
and Hossard^ of whom we have already had occasion to make
honourable mention in another part of this essay, found them-
eelves on several occasions, involved in the heart of clouds in which
thunder-storms were raging. This was the case at the summit of
the Peak d'Anie, 8215 feet high, on the 15th of June 1825 ; and
also on the 20th, the 24th, and 25th of July 1827. The storm
of the 15th of June lasted for six hours. The hair of the ob-
servers, and the strings of their caps, all stood on end, and they
also heard a buzzing noise around the salient parts of their
bodies.

They were similarly exposed at the top of peak Lestibete, at
an elevation of 6007 feet, on the 4th, 5th, 6th, and 13th of
July 1826. During the storm of the 13th, great hailstones fell
of about an inch in diameter.

Again, upon the mountain of Trournouse, at an elevation of
10,124 feet, they were exposed to storms on the 9th and the
] 3th of August 1826. The storm of the 9th lasted for twenty-
four hours, during which it both hailed and rained much, and
the thunder-claps were exceedingly frequent. The tent, in
spite of three folds of very thick cloth, placed one over an-
other, sometimes appeared as all on fire. The loaded guns of
M. Hossard, left for precaution's sake on the outside of the
tent, exhibited next day many traces of evident fusion at the
end of the barreL This storm appeared so violent in the val-
ley, that the inhabitants of Heas never hoped more to see either
the two officers or their guides.

Pinally, they were in the midst of thunder-storms on the peak

Does the Lightning striJce before it becomes visible ? 143

o( Baktous, 10,321 feet high, on the 25th, the 30th and 31st
of August 1826. On these occasions, they experienced rain,
hail, and snow ; the lightning possessed extreme vividness, and
the thunder followed instantaneously. On the 31st the light-
ning fell upon a white partridge which the guides had hung
with a piece of pack-thread, upon a stake of wood. The end of
this stake was found charred ; a stripe of feathers also had
been removed from the partridge from the head to the tail.
From the village of Arrens the storm had appeared so violent
that the travellers on the peak were never expected back again.

Does the Lightning strike before it becomes visible ?

I much question if any natural philosopher has, for some
years, hazarded publicly to propose the question at the head
of this section. During this period it has been supposed that
nothing could, by possibility, be more rapid than lightning.
A well determined velocity of eighty thousand leagues a
second, appeared so astonishing, that the imagination never
ventured to think of going further. The experiments, how-
ever, of Mr Wheatstone will probably effect a change upon
this point. These have, in truth, I will not say demonstrated,
but they have at least led us to conceive the possibility of even
greater velocities than that of light ; and that, in a substance
whose identity with lightning, a hundred comparisons tend to
establish. The suspicion then announced, at the head of this
chapter, merits investigation in a theoretical point of view.
Meteorology must gain by the inquiry ; and I imagine the pro-
blem has a relation, on some points, to physiology. Finally, it
appears to me that many timid individuals will be spared many
poignant moments during thunder-storms, were it proved that
nothing is to be apprehended when the flash has been seen.

Mr Thomas Olivey, a farmer in Cornwall, who was knocked
unconscious to the ground by a fearful thunderbolt on the
20th of December 1752, so little heard the noise, or perceived
the light of the meteor, that in coming to himself at the end of
a quarter of an hour, his first inquiry was, Wlio had struck
him? A man was struck with lightning hear Bitche, on the
11th of June 1757. After being for a time asphyxiated, he
was asked, on returning to consciousness, by the Abbe Chappe,

144 Means of Protecting Edifices.

What had been the nature of his sensations ? when he answered,
I heard nothing, I saw nothing. The rector of Saint-Keverne,
in Cornwall, Mr Anthony Williams, was struck on the 18th of
February 1770, by the same thunderbolt which did so much
damage in the parish church. On recovering, after having
been long in a fainting state, he declared he had neither seen
the lightning nor heard the thunder. Mr Luke Howard inter-
rogated the survivor of one of two gardeners who were thrown
unconscious to the ground in a country house in the neighbour-
hood of Manchester. This individual, George Bradbury, po-
sitively declared that he had neither heard the thunder nor see7i
the lightning at the moment of the accident. On the 11th of
July 1819, a thunderbolt broke upon the church of Chateau^
netif-les-Moutiers, near Digne, in the Department of the Low
Alps ; it killed nine and wounded eighty-two pe?'Sons, Among
these last was the curate of Moutiers ; he was taken up com-
pletely asphyxiated ; his surplice was in flames. He revived
two hours after the accident, and declared " that he had heard
nothing, and knew nothing of all that had passed." Mr Rock-
well, who was struck with lightning in August 1821 , had neither
seen the lightning, nor heard the noise. H. N. Reeves, a work-
man, who, in June 1829, was labouring on the steeple of Salis-
bury, fell down unconscious immediately after a vivid flash of
lightning : when he awakened from his deep unconsciousness,
he stated that he did not perceive the lightning at the moment
of his fall.

(7b be continued in next Number.)

On the Geology of the Neighbourhood of Kelso, By Charles
Le Hunte, Esq. In a Letter to the Editor.
Deae Sir, — During a short residence at Kelso, in the course
of the present autumn, I made some observations on the neigh-
bouring rocks, that appear worthy of attention. In walking to
the picturesque village of Yetholm, I was agreeably surprised,
when within about two miles of it, to find that the red sandstone,
the prevailing stratified rock of the district, appeared to have
been altered, by the pyrogenous rocks that abound in the neigh-
bourhood. The sandstone is here, usually, of a deep colour,
very fine grained, and contains minute particles of mica, as wellj
as of a white dull mineral. The first indication of change, is

On the Geology of Kelso, 145

the increased liardness of the stone, and the collection of
the white substance into sub-globular concretions. Where
the change has proceeded further, this substance has as-
sumed, more or less perfectly, the crystalline form of fel.
spar. As the altered rock only occasionally appears above
the surface, in this place, the observer has but few oppor-
tunities of examining it : one of these, however, deserves notice.
About a mile from Yethoim, east of the road, near a stream, a
small portion of the rock is visible, on examining which, the
altered sandstone is found in contact with a greenish felspar,
containing crystals and concretions of the same substance*
Whether this is the sandstone, still more altered, I shall not
venture to say ; but this is not improbable, although it is found
high on the Cheviots. Well aware of the various sources of
error which prevent inquiries of this nature from being satis-
factory, I valued but little, at the time, the observations made
near Yethoim. Although my experience as a geologist — if one
may assume that much abused title, who carries a hammer only
for amusement — is but limited, it may be interesting to notice
some of the sources of error to which I have referred, as it will
enable me to introduce a few observations, made in a country
abounding in remarkable geological phenomena. When a
pyrogenous rock, in forcing its way to the surface, breaks
through, and is much mixed with, a sedimentary deposit, they
occasionally form a breccia, in which the characters of both rocks
are in some degree altered. The former, acting as a cement, is
frequently earthy or granular, while the fragments of the latter
exhibit proofs of having been heated, and — which deserves
notice — are often penetrated by the cement, to a degree that
renders it difficult to distinguish them. The characters of the
mixed mass, thus formed, will vary, according to the degree of
friction to which it has been exposed, and to the distance from
the pyrogenous rock. The latter is often mixed to a consider-
able depth, with matter derived from the mass through which it
has broken, so finely divided as to alter its characters but little;
and where no part of it in a purer state is visible, the whole
may easily be mistaken for an ordinary mechanical deposit,
altered by heat. A case somewhat similar to this occurs at
Pwllheli, in Carnarvonshire, where compact felspar is intimately

VOL. XXVI. NO. LT. JANUARY 18 J9. I

146 Mr Le Hunte on the Geology of

mixed with black slate, through which it has broken. The
mass of felspar, however, that may here be examined, as well as
that of the mixture, into which it graduates, is so great, as to
prevent any mistake in determining the nature of their connec-
tion. The upper part of the felspar, for a short distance, is
composed of rather large, sub-globular concretions ; and it is a
remarkable fact, that the pyrogenous rocks of this district have
often assumed the concretionary structure. The upper bed of
columnar felspar, at the interesting mountain Cader Idris, often
exhibits what may be called an incipient concretionary struc-
ture, giving it much the appearance of a sandstone, the grains
of which have been softened and agglutinated by heat. A fels-
pathic rock, generally compact, but occasionally granitoidal, ex-
tends from Carnarvon nearly to Bangor, where it becomes
coarsely granular, and resembles a sandstone. The passage
from the compact to the granular state, although gradual, is so
rapid, that it may be seen in a hand-specimen ; on discovering
this fact, T concluded that the felspar was derived from a sand-
stone by the agency of heat. To this conclusion I was, in
some degree, led, by what I had seen in Anglesea ; where there
is reason to believe, as Mr Henslow has observed in his geo-
logy of that island, that an imperfect granite, very similar to
that near Carnarvon, has been formed by the action of heat on
the old red sandstone. It appears more probable, however,
until further evidence be procured, that the apparent sandstone^
near Bangor, is concretionary and derived from the felspar,
than that a ridge eight miles in length of the latter is derived
from the former, so completely changed by heat, that no trace
of its original character remains. This ridge extends westward
of Carnarvon, where it is formed of sienitic greenstone. Geo-
logists have discovered what they consider volcanic tufas among
the transition-rocks. Such tufas certainly exist in North Wales ;
and if the term may be applied to breccias, in which foreign
fragments are embedded in a volcanic cement, they occur there
more frequently than in any other part of Great Britain. In
some instances, the fragments appear to have been entangled in
the volcanic rock when forcing a passage to the surface ; in
others, there can be no doubt that the cement, although com-
pact, and containing both crystals and concretions of felsp

1

the Neighbourhood of Kelso. 147

has been deposited by water. An interesting example of such a
formation occurs a few miles to the north-east of the beautifully
placed village of Festiniog, near some small lakes, where a rock,
is found, composed of fragments of black slate and steaschist,
united by a felspathic cement. This breccia has evidently been
exposed to a violent heat, and as it lies over, and graduates into,
an extensive bed of felspar, similar to its cement, while the frag-
ments, in this place at least, exhibit the marks of having suffered
from friction ; it has probably been chiefly formed by the action
of water on the heated mass of felspar, to which it has conveyed
the black slate and steaschist. In one part of this breccia, I
found the fragments blended with each other as if they had
been fused, forming a compact mass, without the intervention of
any cement ; a proof of the violent heat to which they have been
exposed. This brief notice of the more remarkable instances
that I observed in Wales, of the passage of a pyrogenous into a
fragmentary, or apparently fragmentary, rock, may serve to
shew that the question, whether a rock be metamorphic or not,
is sometimes difficult to decide. The causes to which I have
attributed the mixed and doubtful character of these Welsh
rocks, have seldom acted singly ; they have more frequently
united in forming the same mass, rendering its appearance very
variable. This has been the case in the rocks to which I have
referred, near Pwllheli and Festiniog, which are extensive ; and
we constantly meet others in this interesting district, whose re-
markable and variable characters can be accounted for only by
supposing that all the circumstances mentioned, have attended
their formation. This is also what might be expected, where
many of the pyrogenous rocks, after breaking through soft
slates, were immediately exposed to the action of water. Under
circumstances equally varied, appears to have been formed the
very remarkable greenish rock, by some geologists called grey-
wacke, to which the English lake district is so much indebted
for its beauty. It spreads over a considerable extent of country,
presenting the characters of fragmentary, concretionary, and
pyrogenous rocks ; always, however, retaining that similarity of
appearance, which proves that the whole belongs to the same
formation. What appear, at first sight, to be fragments in this
rock, are often flattened concretions, usually of chlorite ; and,

K 2

148 Mr Le Huiite on the Geology of

where these abound, it has a striking resemblance to the older
chlorite slate.

The geology of Wales, and that of the lake district, throw much
light on each other, and should be studied together ; but the geo-
logist must use the now-neglected crucible as well as the hammer.
These two regions afford excellent opportunities of ascertaining
the origin of slate, which appears often to be connected with
volcanic rocks. In both the variety of the latter is consider-
able, while their colours, and apparently their composition,
are frequently similar to those of the slates ; so that the nature
of their connexion might probably be ascertained by chemical
analysis added to attentive observation. I met a black slate in
Wales containing numerous crystals, apparently of felspar, but
soft, opaque, and partaking in the slaty structure. A yellow
slate, well worthy of attention, containing concretions, occasion-
ally crystals of hornblende, is found near Festiniog; but it ap-
pears to be metamorphic. Besides the various characters im-
pressed on the Welsh rocks by the causes already mentioned,
there can be no doubt that they have, very generally, been al-
tered by heat long after their formation ; to which case geo-
logists, I believe, confine the term metamorphic. The frequent
proofs that he discovers of this fact may lead an inexperienced
geologist, as it led me for some time, to attribute all the pheno-
mena that I have noticed to this cause alone ; and, if disposed
to theorize, he may form various ingenious and plausible con-
jectures as to the origin of these rocks, whether in beds or pro-
truded masses, whose claims to the title of pyrogenous appear
doubtful. Such conjectures would receive some support from
the fact, that we find, in the same district, rocks decidedly of
aqueous origin, similar in composition, and often in some of
their other characters, to the more remarkable of those whose
origin may be considered doubtful. The two slates last no-
ticed afford examples of this; and near Festiniog others maybe
seen. My space, however, forbids me to say more on this sub-
ject ; but I cannot leave North Wales, without noticing another
of its rocks. The coarse sandstones and conglomerates, which
we there so frequently meet, often exhibit proofs of haying been
in a soft state ; but whether they are concretionary, or have
been softened by heat, is not easily determined. In general,

the Neighbourhood of Kelso. 149

the latter opinion appears the more probable; but there are
cases in which it seems necessary to adopt the former; nor is it
unlikely, that while the coarser matter was softened by heat, the
finely divided formed concretions. In such rocks, we often find
that the pebbles, although tolerai)ly large, fit into each other,
leaving no intervening space; while the fragmentary character
occasionally disappears, and the mass becomes crystalline.
They occasionally contain cubic pyrites, generally in small crys-
tals; but I once found a large one, which was easily dislodged,
leaving a cast, whose sides were smooth and brilliant as glass;
a plain proof that the coarse, siliceous particles, of which the
rock is composed, were soft when the crystal was formed. This
fact is the more interesting, because the mass in which it was
observed has the ordinary characters of a conglomerate, rarely
exhibiting any other proof of its having been sol't : it is the same
which, regularly stratified, we pass over, for a considerable dis-
tance, in ascending Snowdon from Llanberis.* Decidedly con-
cretionary rocks are more common than is generally believed.
The upper part of the gneiss in Bute, near the Kyles, is the
most interesting example that I have seen. The quartz and
felspar are indistinct, and rather large concretions wedged in-
to each other. This graduates into a coarse sandstone, similar
in composition, which is probnbly also concretionary. A chlorite-
slate, similar to this gneiss, is found in Dumbartonshire. There
is reason to believe, that what Dr M*Culloch considered frag-
nientary beds among the primary rocks of the wer.t of Scotland,
are concretionary. But my space compels me to return to
Tvveeddale.

From Kelso I visited the beautiful remains of Melrose Abbey,
and, having a little time to spare, ascended the Eildon Hills. On
examining, in such quarries as I met, and they extend from
their base to a considerable height, I could not avoid very
strongly suspecting, that the porphyry of which they are chiefly
composed, was derived from the red sandstone, altered by heat.
In some places the rock is not porphyritic, but has the appear-
ance of a hardened sandstone ; in others the porphyritic charac-

* May not steam, under pressure, have contributed to soften and alter

rocks \

150 Mr Le Hunte on the Geology of

ter is imperfectly developed, sub-globular concretions supplying
the place of crystals. In the very shght examination of these
hills, however, that my time enabled me to make, I saw nothing
so very peculiar in the characters of the porphyry, as to lead me
beyond a suspicion that it was formed from the sandstone ; for
I recollected that the latter, when fine-grained, might closely
resemble the paste of a clay-stone porphyry, while the similarity
of colour, although striking, might be accidental. Having heard
that the remains of a vitrified wall existed on the Black Hill, near
Earlston, 1 resolved to visit it, and here my suspicion was car-
ried to conviction, in spite, I may truly say, of frequently re-
curring incredulity. This hill is said to be 1200 feet above the
sea-level ; but it is not much higher than the sandstone which
forms the greater part of its steep western side ; while its sum-
mit is formed of porphyry, as well as its eastern declivity, which
is so gradual that it is occupied by a luxuriant field of turnips.
Excepting in one spot, on the western declivity of the hill,
where it rests on the sandstone which it has slightly altered,
there is no large continuous mass of the porphyry visible ; but
it frequently appears above the surface, which is generally
covered by its fragments. I twice visited this remarkable hill,
and every step I took upon it, every stroke of my hammer,
served to remove the incredulity I had previously felt, and to
convince me that my opinion, as to the origin of the porphyry,
was well founded. It is difficult to state, in words, all the evi-
dence which influences the mind in inquiries of this nature ; for
it often consists in minute resemblances that cannot be described.
I must be satisfied by saying, that I collected specimens from
different parts of the hill, that plainly exhibited a passage from
the sandstone, through various degrees of change, into the por-
phyry. The similarity of colour in the two rocks, usually a
blood red, while it had some influence on my opinion, made me
hesitate to adopt it, as it is common both in sandstone and por-
phyries ; but having now observed it in three places, distant from
each other, I could not avoid giving it more weight. The por-
phyry here, however, varies in colour, through difi'erent shades
of red and impure yellow, while it is occasionally spotted ; just
what might be expected, supposing my opinion to be correct.

the Neighbourhood of Kelso. 1 51

It is also frequently lamellar — a fact which would have little
weight, as pyrogenous rocks occasionally assume this structure,
but that the arrangement and thickness of the lamellae, are pre-
cisely the same as in parts of the neighbouring sandstone. When
on the point of taking my final departure from the hill, I met a
mass of porphyry, so remarkable in its characters, that it banish-
ed all doubt as to the correctness of my opinion. The surface
of this mass presented stripes, alternately of a deep and light red
colour, which, while they preserved their relative thickness and
parallelism, were bent and twisted, just as we so often see the
lamellae of gneiss and mica-slate. The regularity with which
the plates of different colours preserve their relative thickness
throughout the stone, its striking resemblance to the striped
sandstone of the district, and the difficulty of accounting for its
characters, unless we consider it a portion of this sandstone, soft-
ened and altered by heat, are sufficient to prove that my opinion
is well founded. As this singular block of porphyry lay on the
side of the hill, I have no proof that it ever formed a part of it ;
but its characters leave no doubt that it belongs to the same for-
mation, which is found, I believe, along the whole of Tweed-
dale, forming insulated, often conical, hills; and supposing that
it has travelled from some of these, it proves that at no great
distance, the resemblance between the porphyry and sandstone
is still stronger than at the Black Hill. I was obliged to leave
Kelso immediately after my second visit to this interesting spot,
and, as it is probable that I shall never revisit the lovely banks
of the Tweed, I trust that my observations may attract the atten-
tion of some experienced geologist, and lead to further inquiry.
Such investigations derive additional interest from their con-
nexion with some abstruse and disputed questions in geology.
In no district can satisfactory results be more confidently ex-
pected than in Tweeddale, on account of the simplicity of its
structure, and the frequency with which the rocks are well ex-
posed. I shall conclude by observing, that wherever I have
used the word felspar, excepting in one or two instances, it is to
be considered the soda-felspar, for which there are now at least
four names. As labradorite is its most beautiful, and, in some
respects, most characteristic, form, if it were distinguished by

152 Sir John Graham Daly ell on a Singular Mode of

this name alone, much confusion would be prevented, and the
relative composition of rocks kept in view. — I remain, dear Sir,
your's, &c.

Chas. Le Hunt.

To Professor Jameson, Edinburgh.
November 1838.

J Singular Mode of Propagation among the Lower Animals il-
lustrated. By Sir John Graham Dalyell. Communi-
cated by the Author.

In preceding memoirs I have endeavoured to explain the pe-
culiarities observed in the propagation of several zoophytes,
Avhether by means of ova giving birth to the young, whether
through the medium of an animal discharged from an external
cyst, or pod, or vesicle of the parent, which, at first enjoying
active motion, becomes stationary, undergoes a metamorpho-
sis, and then appears in the perfect state. Likewise it has
been shewn that prominences bud externally from the hydra
tuba, which is a hydra proper, shapeless at first, and as they
detach, becoming perfect animals ; and that an animated mov-
ing corpusculum, which may be artificially liberated as such
from the actinia, will become a perfect foetus if retained, and
will be produced by the parent from the mouth in its own si-
militude.

I. Actinia. — All the species of actinia are not viviparous by
the mouth. There is one inhabiting our seas which I cannot
identify with any described in the systema of any author, and
which may be provisionally named Actinia flava. This is a
beautiful animal, always of a yellowish or orange hue, begirt
with a row of longitudinal white lines down the whole body.
The disc is encircled by a triple row of rather slender long ten-
tacula ; and the basis spreads in a very thin margin around
the body affixing it below. The whole animal might be cir-
cumscribed by three-fourths of a hollow sphere, an inch or
somewhat more in diameter.

Preparatory to propagation considerable irregularities appear
in the margin of the base ; it is penetrated by deep indenta-
tions, or enlarges by wider diffusion of some of the edges.
Jn a short time, crude and irregular portions of indefinite

Propagation amoiig the Lower Animals. 153

shape are visibly detaching themselves from the circumfe-
rence. Some resemble solid prisms ; others approach a long,
oval, or other figure ; next, the margin seems contracting with^
in a narrower circuit, while the separating fragment either re-
mains stationary or recedes from it. A connecting ligament
now appears between them, which gradually attenuates until
complete separation ensues.

Still the fragment is a shapeless mass, but the subsequent
evolution of tentacula and its more symmetrical form, prove its
identity with the nature of the parent. By a number of frag-
ments detaching thus, in the course of a season, the parent is so
completely mutilated that it can be scarcely recognised as the
same animal.

The attenuating ligament is somewhat above the substance
sustaining the actinia; it extends from two to eight or nine
lines, is free of adhesion below, and waves with the motion of the
water ; but it is too opaque to expose the circulation of a fluid,
if there be any, between the parent and the embryo actinia
before their connection is dissolved.

II. Mcidi a papilla. — In the middle of summer, I observed
a minute animal among a quantity of marine collections,
wherein the Flustra carbasea formed the principal j)art. It
narrowly resembled a pin, such as is used in apparel, extended
about a line, and was of a reddish colour. A rude sketch ha-
ving been taken, it suddenly disappeared ; but I named it spi-
nula for the purpose of recognition.

Exactly five years afterwards it occurred again on the same
day of the month, the 19th of July, under similar circumstances.
I was inclined to refer it to the globular corpuscula of the
Flustra carbasea as now exhibiting a very peculiar and unusual
aspect, modified, perhaps, at a certain season, or from some un-
known cause.

Being in greater numbers, and under more favourable con-
ditions, I could follow its progress better.

This creature bears considerable resemblance to a tadpole.
The tail is three or four times as long as the body or head ;
the surface uniform, void of external organs, the whole of sohd
consistence. It swims with much activity, chiefly by the ac-
tion of the tail, which is very flexible. (Fig. 1.)

154? Sir John Graham Daly ell on a Singular Mode of

I kept the animals carefully, and obtained correct drawings
of several specimens. They disappeared again ; but now va-
rious minute spots, such as indicate originating zoophytes, re-
mained.

Meantime, having been replaced by a new colony, the spi-
nulae after exhibiting equal activity remained in a vertical po-
sition ; the head in contact with the bottom of the vessel, and
nearly in a state of repose. Next the front of the head en-
larges, angular projections issue from it, and incipient adhesion
by one or more of them ensues. As if unwillingly arrested,
the animal then exhausts itself in convulsive struggles to be free.
The vibrations of the tail are so quick that the eye can scarcely
distinguish its figure. At length motion ceases ; and it becomes
irreversibly rooted.

In a few days, a manifest change is discovered. A dark so-
lid nucleus occupies the place of the head or body of the spi-
nula, and its tail has disappeared. A transparent matter has
diffused around the front, towards the circumference of which
twenty-six or twenty-eight flattened radicles are diverging from
the nucleus as a centre, and distributed among it. (Fig. 2.)
Meantime, the nucleus is consolidating, two nipples with qua-
drangular orifices rise from the upper side. The radicles be-
come inconspicuous below ; the transparent matter forms a
skinny environing basis, and the spinula proves to have been
metamorphosed to a nascent ascidia.

This animal may be now recognised as one the most com-
mon in our seas. Few marine collections are made without its
presence on one or other part of them, which accounts for its
being almost a constant concomicant on the Flustra carbasea.
When mature, it is of various shades from peach-blossom red
to, carmine; and then it might be inscribed in three-fourths of
a sphere, six or eight lines in diameter. (Fig. 3.)

The young ascidiae bred from the spinulae, began to colour
in three months.

This species which is here denominated Ascidia papilla pro-
visionally, belongs to a genus approximating the Cynthia of the
learned naturalist Savigiiy. The orifices of the papillae, or
nipples, are quadrangular, but these parts themselves are not
furrowed or fluted, as those described by that author.

Propagation among the Lower Animals. 155

III. Aplidmm verrucosnm, the Warty Sea-fig. — Early in Oc-
tober, the oyster-dredgers of Newhaven, some of whom have
been in my employment nearly twenty years, brought a quan-
tity of marine products to me, which had beencollected to the
south or south-east of Inchkeith, in the Frith of Forth. Among
these was a gelatinous looking, but solid, compact substance,
which, being suspended by silk threads in a large glass jar of
sea-water, proved of olive-green colour and approached the form
of an irregular parallelopiped above three inches long, and
equalling perhaps three cubical inches of solid contents. The
whole was covered with very low prominences almost even with
the surface.

In a short time the prominences developed as a profusion of
short projecting cylindrical orifices, each fashioned as a lip with
a smooth, even edge, wherein were attracted by a powerful
current and absorbed the neighbouring buoyant particles. After
the lapse of several hours the bottom of the jar was covered by
a quantity of dark ovoidal pellets, discharged from all points of
the common mass, now clearly discovered to be a vast aggre-
gate of animals thus in activity, each not exceeding a line and a
half in diameter, united and incorporated together.

The numerous currents of buoyant particles and their ab-
sorption, the multitude of creatures in action, their sudden
crouching down and rising again to resume it, is a spectacle in-
teresting to the naturalist. It seemed to me, as with the
amphitrite, an animal apparently much higher in the scale, that
they were roused by the presence of muddy matter; and that
they would clear the water of it.

The approaching maturity of numerous internal corpuscules
converted the olive-green of the subject to a brownish colour ;
and as they became more vivid the skin seemed to become daily
thinner.

At length a number of spinulae, narrowly resembling those
of the preceding paragraph, appeared in the vessel. There
could be no doubt of their origin. But they vanished speedily,
though diffusing specks remained as before.

Having altered the position of the specimen and introduced
smaller vessels below, so as to receive whatever it might produce.

156 Sir John Graham Daly ell on a Singular Mode of

I found several spinulae swimming there in twenty-four hours.
Nothing else could be found.

However a number of oval yellow or reddish corpuscules
next appearing at the bottom of the smaller vessels, they proved
so many ova under the microscope, each containing a visible
embryo spinula.

Some had nearly attained maturity ; the head or body formed
the centre encircled by the tail as a circumferential border ; all
contained within an exceedingly transparent integument or am-
nios. All the ova were motionless.

This was an important observation, for it leads to the solu-
tion of certain difficulties perplexing even very learned natura-
lists, who have been inclined to deny the animal nature of those
beings in activity which are indisputably an earlier stage of
zoophytes becoming permanently rooted in a later stage.

I now beheld an inert ovum — necessarily inert, because this
constitutes one of the principal elements in the definition of an
ovum ; it is a stage of organic existence, void of locomotion.
But, subsequent to impregnation or when the organic matter of
the ovum is advancing to another stage, the embryo is at first
in a passive, and then in an active organic state, which may exhibit
the locomotive faculty before production, as seen in some planariae,
traversing the capsule enclosing them, and in other animals.

Those observers, therefore, who witness the activity of the
corpuscles from the flustrae, or of the planulae from the sertula-
rias, or of the spinulae from the ascidia, suppose it only the
first, while truly seeing them in the second stage. They have
quitted the ovum.

The evolution of the spinula in the present subject, follows
production of the ovum so speedily as accounts for the diffi-
culty of finding it in this earlier stage.

The spinulas having escaped their prison, they traverse the
water with considerable activity, in all different directions, and
assuming all different positions ; their motions and their figure
bearing a near resemblance to those of tadpoles. Sometimes the
spinulae of the preceding paragraph continue ten or twelve days
in motion. Here it relaxes sooner; their transition is less fre-
quent and more circumscribed ; they are seen with the head
down and the tail erect as the others, almost stationary, but

Fropagation amovg the Lower Animals. 157

many afford a more favourable opportunity for observation, "by
their horizontal or oblique position. Angular projections soon
issue from the front of the head ; and by means of their contact
with the neighbouring surface of the vessel, adhesion ensues.
While apparently slight, the animal struggles to free itself, but
it beconies rooted also as a preliminary to its metamorphosis.
The upright tail disappears, and a central yellowish nucleus re-
mains soon converted to the palest green.

Meanwhile eight, or about that number, of radicles are is-
suing from the circumference of the nucleus, diffuse themselves
on the glass amidst a thin transparent matter, by the outline of
which they are bounded. In eight days two orifices with circu-
lar lips have opened above into the cavity of the nucleus, and
through one of these the pulsation of a large internal vessel may
be distinctly seen, together with the course of dark atoms, dis-
tributed along with a circulating fluid through numerous chan-
nels to remoter parts. Buoyant particles are next absorbed,
and pellets ejected. Another ascidia has been produced.

But this animal is only the first of a group which shall be
formed of hundreds. Whether it be the centre of a system
of animals into which the eight radicles shall develope I cannot
affirm positively. The specimen itself seemed to be composed in
some parts of eight or more ascidiae surrounding a central de-
pression, not unlike the superficial depressions appearing in the
sponges of commerce. Naturalists speak of a system or set of
animals composing analogous products, though imperfectly ex-
plained or understood for want of observation as living specimens.
Instead of disappearing as in the preceding ascidia, the radicles
enlarge here into an oval leaf affixed below, where the nucleus
is connected with it by an attenuating channel. I call it a
channel, for at a certain stage, when a month old, the circula-
tion is evidently carried on between the nucleus and the enlar-
ging radicles. But there is the same difficulty of preserving
these subordinate parts as of preserving the young tubularia?,
or flustra?. They have too little consistency for their feeble life
to resist the injurious consequences incident to so artificial aeon-
dition as attends removal from their natural site. The nucleus
readily survives : it seems then to become double, and a smaller
ascidia buds from each of the two. Five or six were generated
thus, from one, in ten weeks.

158 Mr Galbraith on Trigonometrical

It is difficult to form a satisfactory theory of the peculiar na-
ture of the metamorphosis of either ascidia. Probably the body
of the spinula is occupied by the transparent matter, which on
expulsion diffuses around the front, next the radicles may be a
prolongation of the external skin amidst it, somewhat after the
nature of gemmination, and thus they form together the basis of
the nascent ascidia.

From the J)receding observations, it may be deduced, Ist^ that
two different modes of propagation carry on the race of actinia,
one whereby the embryo, a shapeless corpusculum, endowed
with locomotion within the parent, is produced symmetrical by
the mouth, but then deprived of that faculty or nearly so. The
other whereby a fragment buds externally from the base, thus
generating after the fashion of the hydra tuba.

9.d, That the Aplidium verrucosum, a compound ascidia, is
originally an inert ovum, next an embryo endowed with an ac-
tive locomotive faculty, which in the third stage is converted to
an animal of a form absolutely different, rivetted to the same spot.

3cZ, That the zoophytes of certain genera pass through inter-
mediate stages towards perfection, of which that stage exhibiting
them endowed with the faculty of locomotion is not the first.

All the preceding names are given provisionally.

Fig. 1 Fig. 2. Fig. 3.

Fig. 1, Spinula of the Ascidia papilla enlarged.
Fig. 2, Diffusing base viewed from below, enlarged.
Fig. 3, Ascidia Papilla^ adult, natural size.

On Geodetical Surveying and Trigonometrical Levelling. By
William Galbraith, Esq. M. A. ; M. S. A,, Teacher of
Mathematics in Edinburgh. Communicated by the Society
of Arts.

The method of surveying and levelling trigonometrically, is
now almost universally employed where accuracy is required,
and various attempts have been made to simplify the more usual
calculations. In consequence of being frequently employed in

Surveying and Lerelling. 159

giving instructions on this subject, I, have found it convenient
to draw up a few rules, and construct some auxiliary tables,
for the use of the practical man, without troubling him with
the mathematical investigations. These I beg leave to lay be-
fore this Society, and should they meet with the approbation of
its members, the publication of them will, perhaps, be useful to
that class of surveyors.

The tables are formed upon the usual formulae, derived from
the consideration that the earth is an oblate elliptical spheroid,
of 3J5 of compression.

This I arrived at some years ago, and I have generally been
endeavouring to test the accuracy of the measures of the earth's
axes which I had then adopted, by a careful comparison of
them with those that successively came to my knowledge, and
the general accuracy of my numbers, will be obvious from the
following values : —

Equatorial Radius.

Polar Semiaxi*.

1.

Galbraith,

20922642 feet,

20852900 feet.

2.

Francaeur,

20922677 ...

20854072 ...

3.

Smidht,

20922114 ...

20851834 ...

4.

Airy,

20923713 ...

20853810 ...

5.

Puissant,
Means,

20922037 ...

20853649 ...

20922637 feet.

20853253 feet.

llence, the mean equatorial radius derived from all these is
less than what I have obtained by 5 feet only, while the polar
semiaxis is greater by 853 feet. These means give a compres-
sion of ^ nearly, and the differences, in general, are so small,
as in this case to be quite immaterial in almost any practical
application to the purposes of surveying. It is clear, there-
fore, that the data on which my tables are founded, differ little
from those of the highest authority, and consequently the re-
sults derived from their employment are sufficiently worthy of
confidence.

In deducing latitudes, longitudes, azimuths, and heights,
geodetically, it is necessary to convert any distance measured
in feet on the earth's surface into arcs, and hence the radius of
curvature of the measured arc, in any given position on the
terrestrial spheroid, is required by the principles oi the conic
sections.

160 Mr Galbraith on Trigonometrical

Let r be the radius of curvature of the meridian, or normal
to the major axis of the elliptical spheroid, then, if a denote the
radius of the equator, b the polar semiaxis, and I the latitude.
«2 52

■(a2 cos H-\-b'^ sin H)

0)

Again, if g be the radius of curvature of the arc perpendicular
to the meridian, or the normal to the minor axis.

/2

^"{a? cos H+b^ sin 2/)^ .... (2)

Lastly, let / be the radius of curvature of an oblique arc,
making an angle a with the meridian.

^^2 •

^~(«2cos2/+62sin2/)icos2^+62(«2cos2/+62sin2/)|sin2* • (^)

Now, as the radius of curvature is to an arc R'', equal to the
radius in seconds, so is the distance in the same measure with
the radius of curvature, to the corresponding arc in seconds.

From this analogy, and the preceding three equations, will
be obtained the factor to convert feet into seconds on the sur-
face of the terrestrial spheroid in any given direction.

Wherefore, if M be the factor to convert a curvilineal dis-
tance on the meridian into seconds of arc ; P, that on the per-
pendicular to it ; and O, that on any oblique arc, making an
angle a with the meridian, there will be obtained

M=^.(a2 cos 2/4.52 sin ^/) ^ .... (4) '^

P=~(a2cos2/+62sin 2/) ^ . . . .(5)

0=M cos 2^+P sin 2^ (6)

■p // T> //

Log-2-^-2=6.0348593, Log -^=0.6731921

From these formulae, tables I, IV, and V,* have been con-
structed. The first table is certainly less extended than might
be desirable in some cases, but it is sufficient for most purposes
of surveying, especially for nautical men, who are frequently

* For table V, log -^^=0.0348421, log —=0.6732241, in which a is
20921872 feet, and h is 20854078 feet.

Surveying and Levelling. 161

employed in various latitudes, where many of the more extended
special tables will not apply. I allude to such tables as those
given by Puissant, &c. expressly calculated for a few degrees
of mean latitudes. I have also, on the preceding principles,
calculated from the same data similar tables (IV and V), ex-
tending between the latitudes 50° and G0% embracing the limits
of the British trigonometrical survey. The logarithmic values
of M and P are given to every KX of latitude, in table IV',
being most generally wanted, as well as those of O, though
to every 10° of azimuth only, since they are less frequently re-
quired, and for any intermediate degree of azimuth, the values-
may be found by interpolation with sufficient precision.

Previously to the determination of heights trigonometrically,
the curvilineal distance, or its chord at the level of the sea, ought
to be augmented for the height of the lower station, since the
radii passing through their summits diverge proportionally to
that height. This correction may be obtained by the following
formula, or the results derived from it, arranged in a table (II).

Let K be the chord of the augmented arc A, at the height
A, derived from the arc a, at the level of the sea, then,

LogK=loga+ — ^_— ^=loga+w/t— joa2 .... (7)

in which M is the logarithmic modulus, and g the radius of
curvature of the same name as a, or in feet, as in table II. In
the construction of the table, I have adopted mean values from
the same data as before, because they are sufficiently accurate
for this purpose, and have assumed the mean effect of terres-
trial refraction, equal 0.08, or about y^- of the intercepted arc,
which appears to be nearly the mean value derived from obser-
vations made in Britain and France.*

The third table has been calculated to correct results from
using, in certain computations, connected with this subject — •
common logarithms, instead of log. sines and tangents, in the
case of small arcs. This gives facility with sufficient accuracy,
especially, when the sm^dler classes of logarithmic tables are

^ Conversely, this table will reduce the log. of a base measured at any
height h above the sea, to that level, by applying mh and pa\ with con-'
trary signs.

VOL. XXVI. NO. LI. JAXUAUY 1839- ^

162

Mr Galbraith on Trigonometrical

employed. The fourth and fj/lh tables have already been ex-
plained.

Practical Rides.
To illustrate the method of employing these tables in calculation, let P
be the north pole in this instance, E a point in the equator, B a point of
which the latitude and longitude are known, T another place whose
bearing and distance from B are given, and from these the latitude and
longitude of T, and the azimuth of B from T, are required.

Also let PBE be the meridian passing through B, PTF the meridian
passing through T, PBT the azimuth de-
noted by a in the tables, or m' in the formu-
la, BT the distance or curvilineal arc a in
feet, of which the chord is k, Tx a perpen-
dicular from T, the required point upon
the meridian passing through the given
point B, the distance from the foot of
which from the equator, measured by Ex,
is the latitude of x ; /' the latitude of the
place nearest the equator, / that of the
more distant, and Tl the parallel of lati-
tude passing through T, making E / the
the latitude of T, or that required.

It must likewise be observed that B x is
a small arc of the meridian to be added to
the given latitude in proceeding towards
the pole, or subtracted when receding
from it, to give the latitude of the foot of

the perpendicular x, the argument for taking the log. P from the tables.
The argniment to obtain M is half the sum of the latitudes approximately
or 4 (/ 4- I'), to be derived from a provisory calculation, in order to get
the mean latitude between the given stations. The number of minutes
to be added to the smaller latitude l' or substracted from the greater /
to get i(J + 1') may be computed from the following rule.

To the constant logarithm 5.914630, add the log. of the meridian dis-
tance in feet, the sum will be the log. of half the difference of latitude
in minutes, or I (Z — /') to be added to /', or subtracted from /, to give
^ (/ 4- I') the middle latitude, sufficiently near the truth for taking
log. M from the tables.

1. By a provisory calculation, such as that just given, or, by a repeti-
tion of the more accurate method now to be shewn, if thought necessary,
find the middle latitude or ^ (/ -j- l').

2. To the logarithm of the curvilineal distance, or arc o, add the
log. cosine of the azimuth, or m, and the log. M from the tables, I., IV,, or

Surveying and Levelling. 163

v., answering to the mean latitude or J (/ -f- V), the sum will be the
log", of an arc on the meridian in seconds, m", to be added to the latitude
/', if approaching the pole, but subtracted from / if receding from it,
the suni or difference will give \, the latitude of the foot of the perpen-
dicular upon the given meridian from the point in that required.

3. To the log. of a add the log. sine m, the azimuth, the log. P an-
swering to X, the sum will be the log p", the perpendicular arc in
seconds.

4. To the log. sine x add the log. cosine p", the sum will be the log.
sine of the true latitude required.*

5. To the log. tangent p" add the log. secant x, the sum will be the
log. tangent u, the difference of longitude, which properly applied to
the longitude of the place of observation, will give the longitude of the
point required.

6. To the log. tangent of u add the log. sine i (^ + l'^, the log.
secant ^ (J, — ^'),t the sum will be the log. tangent c, the conveq^nce
of the meridians of the given and required points, which, added to the
azimuth m', at the latitude nearest the equator, will give m the azimuth
as the latitude farthest from it, and vice versa.

7. To the log. O, answering to the middle latitude and given azimuth
a from the tables I., IV., or V., add the log. of the given distance a, the
sum will be the log. of the intercepted arc in seconds, which measures
the angle between the verticals of the given points.

8. To the log. a add the correction m h, answering to tlie given height, h,
of the place of observation from table II., and from it subtract pa^,
corresponding to a, the sum will be the log. of the chord K, passing
through the point of observation to the point observed.

The number S is the difference of the log. secant of half the angle of
the verticals and log. pa'^, or, with the proper signs, it is, log. sec 4 t> —
log. p a% which simplifies the computation of heights.

9. Since the effect of refraction is taken at 0.08 of the intercepted arc
a, denoted by n, this must be combined in the calculation of heights with
the other parts of the operation.

Galling v the angle of the verticals, then 4 (2w — 1)> =-—0.42 u is the
correction to be applied to the observed zenith distance ^, to get ^„ the
corrected zenith distance.

10. To the log. cotangent ^, add the log. K, the sum will be the log. of
the elevation of one place above the otlier.

• Since the difference between x and the true latitude, / or /', as the case may
be (expressed by the arc x/ in the figure), must always be a small quantity, a
special table will readily give this reduction without a logarithmic calcu-
lation.

i* As ^ {I — /') must always be a small quantity, its secant cannot differ much
from radius ; it may, therefore, generally be omitted as in formulae (8) and (9).

l2

^64 Mr Galbraith on Tngonomeirical

This applied with its proper sign to the height of the first place j ■will
give the height of the second above the level of the sea.
' 11. Since the difference of latitude, the difference of longitude, and
the convergence of the meridians, are small arcs, seldom exceeding a fcvir
minutes, the logs, of the lengths of these arcs, measuring them in seconds,
may be safely employed, corrected, if thought necessary, by Table III.
By nautical men, possessing the ordinary smaller classes of tables in
which there are proportional logarithms, these may be very conveniently
employed, and the results will be sufficiently accurate for almost the
nicest purposes.

12. In this case we have the following formulae : —

P. L. M=log. cos A. + P.L.J9" (8)

P.L. c=:log.coseci (^+0 + P-L.w (9)

In words, the proportional logarithm of the difference of longitude is
equal to the sum of log. cos x, and the prop. log. of the perpendicular
arc ; and the prop. log. of the convergence of the meridians is equal to
the sum of the log. cosecant of the middle latitude, and the proportional
log. of the difference of longitude. When a table for reducing x to lis
employed along with this method, the calculations will be thus rendered
remarkably simple.

Explanation and Use of the Tables.

Table I. This table contains the logarithmic values of M, P, and 0
for the latitudes from 0° to 90° inclusive, to every 10° of latitude, and to
every 10° of azimuth. To the intermediate arguments to the nearest mi-
nute, wliich in all ordinary cases will be sufficiently accurate, they must
be found by interpolation. For this purpose differences must be taken,
and proportional parts for intermediate degrees and minutes found by
proportion.

Table IV. is the same as Table I. expanded between the latitudes 50°
and 60° to every 10' of latitude, and to every 10° of azimuth, which, by
aid of the mean difference for every 10' of latitude for M and P afford
the means of getting these numbers to every minute of argument readily.
To this. Table V. is also similar, but adapted to the spheroid employed
in the trigonometrical survey, having differences to 1' of latitude in M
and P in the right hand side column, with differences for 10° in O at the
bottom to get proportional parts readily, as in the following examples.

Required the log. M for latitude 51° 13'.5, the log. P for latitude 50^
68'.3, and the log. O for latitude 6Q° 4'.5 and azimuth, or a. 73° 13 }

1. To latitude 51° 10' (Table IV.) log. M is 7.994073

Proportional part of difference to 8'4 is 8^ X — 1.2 rr . . — 4

Log. M to latitude 51° 13'.6 is , . . . 7.994069 %

Surveying and LeveJUng. 165

2. To latitude 50'' 50' (Table IV.) log. P is 7.992938

Proportional part S'f^ = 0^ X — 0.4 = — 3

Log. P to latitude 60° 58'.3 is 7.992935

3. To latitude 66° and « = 70° log. 0 is 7.992919

Proportional part for lat. 4'i =: 4^ X — 0.5 = — 2

Proportional part for a 3° J = 3i x — 7.9 = — 26

Log. 0 for lat. 6Q° 4'4 and azimuth 73° 13' = 7.992891

Table II. contains numbers to reduce a base measured at the level of
the sea to any height above it ; and conversely, to reduce a base mea-
sured at any height above the sea to that level, by changing the signs of
of m h and p a'\

By shifting the decimal point, m h in the table may be readll}' got for
any number of feet in h ; but this method cannot be applied to p a*,
where the proportional parts to the first difference ^, must be taken, and
then corrected by subtracting the equation of second difference, or the
equation to a^ in the last column.

Ex. Required the log. K when a = 1G4046 feet and h =: G562 feet ?

Log. a -f-5.2149630

For h = 6000 feet, mhis + 0.0001246

500 -f 104

62 + 13

For a = 100000 feet, /) aMs — 4

64000 .. AjXO.64— Eq. A, =—13X0.64— 1 = — 7

Log. K 5.2150982

Hence the whole correction of the log. a amounts to 0.0001352, or the
fourth place of decimals is increased by unit, and, therefore, in great
heights this correction cannot, consistently with accuracy, be omitted.

The log. S contains the log. secant of ^ v, half the angle of the verticals,
and — pa^ combined to facilitate the computation of heights.

Table III. The title of this table, and note under it, sufficiently explain
its use, taking care to apply the numbers according to their signs, and
it will be found useful when the computer has not very large and exten-
sive tables of sines and tangents, by enabling him to use the smaller
classes of tables readily, while the requisite accuracy for the nicest pur-
poses will still be preserved.

Example 1. Benlomond bears from Edinburgh Observatory N. 73° 12'
40" W. distant 308304 feet, on an arc on the earth's surface at the level
of the sea. The place of the Observer on the Calton Hill was elevated
340.7 feet above the mean level of the sea at Leith, and its geographica

166 Mr Galbraith on Trigonometrical

position was in latitude 55° 57' 22".5 N., longitude 3° 10' 52."5 W., from
■which the summit of Benlomond was observed to have a zenith distance
of 89° 49' 30" ; required the latitude and longitude of Benlomond, and
the height of its summit above the sea, together with the azimuth or bear-
ing of Edinburgh from Benlomond, taking M, 0, and P from table V ?

Distance or a =308304 feet log. 5.488979 5.488979

Azimuth or m' =73° 12' 40" cos 9.460667 sin 9.981082

Mid lat. !(?+?')= 56 4 26 log M 7.993736 x gives log P 7.992853

m" = 0 14 37.9 log. 2.943382,/'= 48' 23".4 log. 3.462914

V = 55 57 22.5

m" + ?' = A =56 12 0.4 sin 9.919594 secant 0.254696

p" = 0 48 23.4 cos 9.999957 tan 8.148516

Benlomond,? =56 11 29.8 sin 9.919551 w=l° 26' 58".5 tan 8.403212,
Longitude of Edinburgh, =3 10 52 .5 W.

Longitude of Benlomond =18in 31s.40= 4 37 51 .0 W.

Mid. lat. |(Z+?') = 56"' 4' 26" sin 9.91895L

Convergence c = + 1 12 10.4 tan 8.322163

Benlomond N. 73 12 40.0 W.

m = m' + c =S. 74 24 50.4 E., the bearing of Edin. from Benlomond.

To 4 (? + V) = 56° 4'.5 and a=73| log. O is 7.992933 log a 5.488979.

a= 308304 feet log 5.488979 log. A + 6

^(2 7^-1)=— 0.42 log 9.623249 log. s + 8

\ ^' —0° 21' 13.9 log —3.105161

^ ..'^ - 89 49 30.0

\ — 89 28 16.1 cot 7.965255^

A h = 2846.1 7 feet log. 3.454248

h = 349.7 3

H = 3195.8 feet, the height of Benlomond above the

mean level of the sea.

When h is small, as in almost all cases in this country, then m h and
pa'^ are nearly insensible.

Example 2. The latitude of Benwyvis in Ross-shir^is 57" 40' 44".2 N.,
longitude, 4° 34' 38".2 W., and the bearing of the station on Tarbetness
is N. 67' 14' 66".4 E., distant 162760 feet, required the latitude and longi-
tude of Tarbetness, and conversely, the bearing of Benwyvis from Tarbet-
ness ?

Suroeying and Levelling, 1 6T

Constant log. page 162, 6.914630

a = N. G7° 15' E. cos 9.587386

a SB 162760, feet, log 6.211548

4 {I— I') = 0» 6'.2 . log. in minutes . . , 0.713664
... I' =s 57 40;.8

4 («+?') = 57 46.0 log. M.tab.v. . 7.993621 x gives log. P 7-992817

mf = 67" 14' 56".4 cos . 9.587405 sin . . 9.964823

a = 162760 feet log . 5.211548 . . 5.211548

m" =: + 0° 10' 20" .3 log. 2.792574, /'=:24' 36".3 log. 3.169188

V = 57 40 44 .2 <

Lat. X = 57 51 4 .5 sin 9.927714 sec . , 0.273991

p" = 0 24 36. 3 cos 9.999989 u'-W W'A log. 3.443179

? = 57 60 56. 0 sin 9.927703 (

4 (« 4- 1') s= 57 45 50. 0 sin 9.92729?

c'=39' e^.B log. 3.370476

u' ^ , . . . 46' 14".40 c' = . 39' 6.80

Correction, (tab. III.) for tan m' — 0 .15 for tan c' — 0.10

M = . . . . — 46 14 .25 E. c = + 39 6.70
Longitude of Benwyvis, . 4 34 38 .20 W. N. 67 14 56.40E.

Longitude of Tarbetness, . 3 48 23 .95 W. S. 67 54 3.10W.

Hence, unless in cases of very great nicety, the logs, of the lengths of
the arcs less than one degree may be used in place of their tangents, since
the corrections are always less than two or three tenths of a second. As
a farther simplification, I would recommend a small table, VI, to reduce k
to /, and then the operation would be brought perhaps to the greatest pos-
sible simplicity, retaining the requisite accuracy.*

Example 3. The perpendicular from the spire of the church of Notre
Dame at Calais on the meridian of Greenwich is 427611.43 feet, and the
arc of the meridian from the observatory of Greenwich to the point where
the preceding perpendicular cuts it is 184282.44 feet, required the lati-
tude and longitude of Notre Dame, the convergence of the meridians, and
the bearing of Greenwich from Calais, the latitude of Greenwich being
61" 28' 38".5 N. longitude 0° 0' 0", and the bearing of Calais from Green-
wich being S. 66* 40' 62".0 E.

• When the Logarithmic Tables now printing by Shortrede, under the care
of Mr E. Sang, are published, they will enable computers to make these calcu-
lations very readily, since the log. sines and tangents are given to every second
of the circle, with proportional parts for decimal fractions.

168 Mr Galbraith on Trigonometrical

\ (I + 0=51° 13' log M (tab. IV.) 7.994069 x gives log. P=7.992935
M' =184282.44 log. . 5.205484 P=427511. 43 log. 5.630948

»»"= 0' 30' 17".8 log. 3.259553 p"=l°10' 6".l log. 3.623883

l=ol 28 38.5

Xrr50 58 20.7 COS . . 9.79913 1 (Z+^')cosec. 0.10817'
/'&Xcor = — 53. 1,/' Prop. log. 0.40954 I

V =50 57 27. 6, «=1 51 19.6 p. 1.0.20867 . • 0.20867

c . . . = 1 26 47.0 Prop. log. . . 0.31684

Calais bears , S. 66 40 52.0 E. from Greenwich.

Greenwich bears N. 65 14 5.0 W. from Calais.

The corrections from Table III. for tangents would be — 2".2 for u,
and — 1".2 for c, -which are too great, making these 1° 51' 17".4, and 1° 26'
45".8 respectively, and even for such considerable distances, these are less
than would arise from a slight variation in the values of the earth's axes.

Hence this last method of computing /, u, and c, is sufficiently accurate
for cases of the greatest nicety, is by far the most simple ; and on that
account, it is recommended to nautical surveyors, who have always a
table of proportional logarithms.

By some surveyors, the log. sine of / or /', as the case may happen, is
employed to compute c, and this plan is certainly very simple, since that
Jog. sine is already found by a previous calculation, but it is not suffi-
ciently accurate for nice purposes, as in our first example the error would
be -f- 6" ; and if this source of error be continued through a considerable
series of triangles, in nearly the same direction, the accumulated error
would be quite inadmissible in very ordinary operations.

In making the necessary observations, the instruments employed should,
by judicious management, be used, so as to produce the most accurate
results of which they are susceptible. Borda's repeating circle, and the
repeating theodolite, as constructed and employed on the continent, pos-
.vess considerable facilities for this purpose. The smaller classes of cir-
cles made in this country, do not, in general, possess the property of re-
petition ; but to gain this, when thought necessary, a repeating stand has
jjeen frequently supplied. It adds, however, greatly to the price, as well
ns to the weight of carriage, and consequently, this addition is frequently
dispensed with. To reduce or destroy any small error in the azimuth
circle, Troughton directed the observer to " turn the whole instrument a
^'mall quantity on its stand, and, upon readjusting it, again to measure
the required angle." This method, no doubt, is advantageous, but it
does not give all the advantage of which it is susceptible. To gain this,
I propose to suggest the following method, which I have frequently used
to advantage. Let r be the number of repetitions required, v the num-
ber of verniers, or reading microscopes, and c the change of position of

QgAO

the first vernier, as A, then c = (10)

Surveying and Levelling, 169

Or in words, the amount of change of zero, or the starting points of A will

be obtained by dividing 360° by the product of the number of repetitions

multiplied by the number of verniers, or even more simply, by dividing the

interval between each vernier by the number of repetitions, the quotient

will be the change of each in degrees. Let the required number of rc-

360°

petitions be fouVf the number of verniers three, then = 30°, the

\z

change. Hence the starting points of A will be 0% 30°, 60% and 90", by
which means the whole circle is equally employed in measuring the re-
quired angle, and the errors of excess and defect will, as I have often
found by experience, even by a moderate sized circle, with a great de-
gree of probability, neutralize each other.

Table I. To convert feet on the Terrestrial Spheroid into Seconds of Arc.

Lat.

Log. M.

Azimuth from the Meridian, or Log. 0.

Log. P.

0°

10°

20°

30°

40°

50°

60°
4535

70°
4149

80°

90°

0°

7.996709

6622

6,371

5986

5513

5009

3896

3809

10

6578

6494

6250

5877

5418

4930

4470

4096

3850

3765

20

6201

6124

5902

5562

5145

4700

4287

3940

3717

3639

30

5624

5558

5365

5082

4726

4348

3992

3701

3513

3447

40

4915

4864

4715

4489

4212 3916

3637

3410

3265

3211

50

4160

4123

4019

3860

3664 3456

3259

3099

2995

2959

GO

3449

3427

3364

3267

3149 3022

2904

2807

2744

2722

70

2869

2859

2829

2783

2728 2669

2614

2568

2539

2529

80

2490

2-189

2480

2468

2454 2439

2424

2413

2405

2402

90

2358

23o8
170°

2358
160°

2358
150°

2358 2358

2358

2358

2358

2358

Lat.

180°

140°

130°

120°

110°

100"

90°

Table II. To reduce a Base at the level of the Sea to any altitude above it-
and conversely, S^c.

h

m h +

a

pa^-

s +

A,

Arg.

Eq.A..

Feet.

Correction.

Feet.

Correction.

Reduction.

1000

0.0000208

100000

0.0000004

0.0000008

26

1

0.8

2000

0.0000415

200000

0.0000017

0.0000034

44

2

1.4

3000

0.0000623

300000

U.OO0OO37

0.0000078

GO

3

1.8

4000

0.0000830

400000

0.0000066

0.0000138

78

4

2.0

5000

0.0001038

500000

0.0000103

0.0000216

94

5

2.1

6000

0.0001246

600000

0.0000149

0.0000310

112

G

2.0

7000

0.0001453

700000

0.0000203

0.0000422

130

7

1.8

8000

0.0001661

800000

0.0000265

0.0000552

147

8

1.4

9000

0.0001868

900000

0.0000335

0.0000699

9

0.8

170

Mr Galbraith on Trigonometrical

Table III. To convert the Values of small Arcs derived from their Lengths
into those obtained from their Sines or Tangents.
A sin a = R" (arc a — sin a) to radius unity.
A tan a i= R" (tana — arc a) zz 2 a sin a nearly.

Arc a.

A Sin a.

A Tan a.

Arc a.

A Sin a.

>,Tan a.

" +

// ___

" +

" __

0" 0'

0.00

0.00

2° 30

2.85

5.71

10

0.00

0.00

40

3.46

6.93

20

0.01

0.02

50

4.16

8.33

30

0.02

0.05

3 0

4.93

9.88

40

0.05

0.10

10

5.81

11.63

50

0.09

0.20

20

6.78

13.57

1 0

0.18

0.37

30

7.84

15.70

10

0.29

0.58

40

9.01

18.05

20

0.43

0.87

50

10.29

20.63

30

0.62

1.24

4 0

11.70

23.43

40

0.84

1.69

10

13.22

26.48

50

1.12

2.25

20

14.87

29.81

2 0

1.46

2.93

30

16.65

33.39

10

1.85

3.71

40

18.56

37. 5

20

2.32

4.65

50

20.63

41. 0

This table gives the same results as the usual approximative rule ge-
nerally given to find degrees, minutes, and seconds, answering to the
log. sine or tangent of a very small arc, and is not perfectly accurate
above two or three degrees, beyond which such calculations should not
be carried.

Table IV. To convert Feet on the earth's surface into Arcs when the com-
pression £ rZ gij.

Log. M.

Azimuth from the Meridian. Log. 0.

Log.P.

Lat.

Colat.

0°

w

20°

30°

40°

50°
3455

60°

70°

80°

90°

50° 0'

7.994160

4123

4019

3860

3664

3259

3099

2995

2959

40° 0'

10

4147

4111

4008

3849

3655

3448

3253

3094

2991

2955

50

20

4135

4099

3996

3839

3646

3440

3247

3089

2986

2950

40

30

4122

4087

3985

3829

3637

3433

3241

3084

2982

2946

30

40

4110

4075

3973

3818

3628

3425

3234

3079

2978

2942

20

50

4097

4062

3962

3808

3619

3417

3228

3074

2973

2938

10

51 0

7.994085

4050

3950

3798

3610

3410

3222

3069

2969

2934

39 0

10

4073

4038

3939

3787

3601

3403

3216

3064

2965

2930

50

20

4060

4026

3928

3777

3592

3395

3210

3059

2960

2926

40

30

4048

4014

3916

3767

3583

3387

3203

3054

2956

2922

30

40

4035

4002

3905

3756

3574

3380

3197

3048

2952

2917

20

50

4023

3990

3893

3746

3565

3372

3192
3185

3043
3038

2948

2913

10

52 0

7.994011

3978

3882

3736

3556

3365

2943

2909

38 0

10

3999

3966

3871

3726

3547

3357

3179

3033

2938

2905

50

20

3986

3954

3859

3715

3538

3350

3173

3028

2934

2901

40

30

3974

3942

3848

3705

3529

3342

3166

3023

2930

2897

30

40

3962

3930

3837

3695

3520

3335

3160

3018

2925

2893

20

50

3950

3918

3826

3685

3512

3328

3154

3013

2921

2889

10

\ 1 1

Surveying and Levelling,
Table IV. — Continued.

171

Lat.

Log. M.

Azimuth from the Meridian. Log. 0.

Log. P.

Colat.

0°

10-
3906

20°
3814

30°

3675

40°
3503

50°
3320

60°
3148

70°

80°

90°

53" 0'

7.993937

3008 2917

2885

37* 0'

10

3925

3894

3803

3(;(;4

3494

3313

3142

i003 2912

2881

60

20

3913

3882

3792

3654

3485

3:^05

3136

2998 2908

2877

40

30

3901

3870

3781

3644

3477

3298

3130

2993 2904

2873

30

40

3889

3858

3770

3634

3468

3291

3124

2988 2899

2869

20

50

3877

3847
3835

3759

3624

3459

3283

3118

2983

2895

2865

10

54 0

7.993865

3747

3614

3450

3276

3112

2978 2891 1

2861

36 0

10

3853

3823

3736

3604

3442

3269

3106 2973 2887

2857

50

20

3841 381! 1

3725

3594

3433

3261

310012968 2882

2853

40

30

3829

3799

3714

3584

3424

3254

3094 2963 2878 |

2849

30

40

3817

3787

3703

3574

3415

3247

3088 2958 2874 i

2845

20

50

3805

3776

3692
3681

3564
3554

3407
3398

3239

3082

2953 2870

2841

10

55 0

7.993793

3764

3232

3076

2948 2865

2837

35 0

10

3781

3752

3670

5544

3389

3225

3070

2044 i 2861

2833

50

20

3769

3741

3659

3534

3381

3218

3064

293912857

2829

40

30

3757

3729

3648

3524

3372

3210

3058

293412853

2825

30

40

3746

3717

3637

3514

3364

3203

3052

2929 2849

2821

20

50

3734

3706
3695

3627
3616

3505
3495

3355
3347

3196

3046

2924

2845

2817

10

56 0

7.993722

3189

3040

2919

2840

2813

34 0

10

3710

3683

3605

3485

3338

3182

3034

2914

2836

2809

50

20

3698

3672

3594

3475

3330

3174

3029

2910

2832

2805

40

30

3687

3660

3583

3465

3321

3167

3023

2905

2828

2801

30

40

3675

3649

3572

3455

3313

3160

3017

2900

2824

2797

20

50

3663

3637
3626

3662

3445

3304

3153

3011

2895

2820
2815

2793

10

57 0

7.993652

3551

3436

3296

3146

3005

2890

2789

33 0

10

3640

3614

3540

3427

3287

3139

2999

2886

2811

2786

50

20

3628

3603

3529

3417

3279

3132

2993

2881

2807

2782

40

30

3617

3592

3519

3407

3271

3125

2988

2876

2803

2778

30

40

3605

3581

3508

3398

3262

3118

2982

2871

2799

2774

20

50

3594

3569
3558

3498

3388

3254

3111

2976

2866

2795

2770

10

58 0

7.993582

3487

3378

3245

3104

2970

2862

2791

2766

32 0

10

3571

3547

3477

3369

3237

3097

2964

2857

2787

2763

50

20

3560

3536

3466

3300 3229

3090

2959

2853

2783

2759

40

30

3549

3525

3456

3351 13221

3083

2953

2848

2779

2755

30

40

3538

3514

3446

3341

3213

3076

2949

2843

2775

2751

20

50

3526

3503
3492

3435
3425

3332
3323

3205
3197

3070

2942

2839

2771

2748

10

59 0

7.993515

3063

2937

2834

2767

2744

31 0

10

3504

3481

3415

3313

3189

3056

2931

'2fr.?0'2703

2740

50

20

3493

3470

3405

3304

3181

3049

•i\yii\

■_';;•_>:, J 7 60

2737

40

30

3482

3459

349413295

3173

3043

2920

•jn-j 1,2756

2733

30

40

3471

3448:3384

3285

3105

303(;

2!H5

2»16

2752

2729

20

50

3460

3438

3374

3276

3157

3029

2909

2812

2748

2726

10

60 0

7.993449

3427

3364

3267

3149

2022

2904

2807

2744

2722

30 0

Diff. foi

•Lat.50°

37

104

159

196

209

196

16(

} 104

36

M<

f

MUiDiff.
Dr 10'

10° of

55

29

83

227

156

166

156

12

B 83

28

M

[- 12

az. —

60

22

63

97

118

127

118

9

r 63

22

I

•= 4

17^ Mr Galbraith on Surveying and Levelling.

Table V. To convert Distances in Feet on the surface of the Terrestrial
Spheroid into Seconds of Arc j when the compression, or i = 0.00824^ that
adopted in the Trigonomet)'ical Survey.

Log. M.

Azimuth from the Meridian, or «

Log. P.

P. P. to
Pin

Log. O.

Lat.

0° -

10°
41310

20°

40293

30°
38740

40°
36838

50°

G0°
.32907

70»

80°

90°

M.

P.

50^

7.9941656

34811

31353

30339

29986

12.1

4.1

51

40930

40595

39623

38135

36313

34368

32542

31053

30081

29743

12.0

4.0

52

40209

39886

38954

37535

35789

33930

.T2182

30756

29826

29503

11.9

4.0

53

39495

39188

38300

36944

35272

33496

31826

30464

29576

29266

11.8

3.9

54

38790

38496

37649

36350

34761

33065

31472

30174

29325

29030

11.7

3.9

55

38092

37812

37005

35770

34254

32640

31122

29885

29078

28797

11.5

3.8

56

37403

37137

36370

35195

33755

32221

30778

29603

28836

28568

11.3

3.8

57

36723

35470

35740 34628

33262

31806

30437

29323

28595

28341

11.2

3.7

58

3G053

35814

35125134070

32777

31398

30104

29048

28359

28118

11.0

3.7

59

35391

35166

34515 33518

32297

30995

29775

28774

28124

27897

10.7

3.6

60

34748

34536

33909 32982

31830

30604

29426

28509

27890

27683

Dif.

. r50°

346

1017

1553

1902

2027

1904

1554

1014

353

for 10°

^-^55

280

807

1235

1516

1614

1518

1237

807

281

in a

•^ (60

212

627

927

1152

1226

1178

917

619

207

Table VI. Correction of y< for p" . Suhtractive.

p"

A

•

0°

10°

20°

30°

40°

50°

60°

70°

80°

90°

0 /

0 0

If
0.00

//

0.00

0.00

//
0.00

//
0.00

n

0.00

0.00

0.00

0.00

0 0.00

5

0.00

0.04

0.09

0.14

0.20

0.28

0.41

0.65

1.35

5 0.00

10

0.00

0.15

0.31

0.49

0.72

1.00

1.48

2.38

4.85

10 0.00

15

0.00

0.34

0.72

1.14

1.66

2.30

3.40

5.40

11.00

15 0.00

20

0.00

0.61

1.26

2.01

2.92

4.11

e.ofl

9.50

9.50

• 19.54

20 0.00

25

0.00

0.96

1.98

3.15

4.58

6.50

' 15.00

30.85

25 0.00

30

0.00

1.38

2.85

4.53

6.54

9.34

13.60

21.50

, 44.20

30 0.00

35

0.00

1.88

3.88

6.17

8.94

12.73

18.50

29.40

1 0.50

35 0.00

40

0.00

2.46

5.09

8.06

11.72

16.62

24.25

38.39

1 19.00

40 0.00

45

0.00

3.12

6.43

10.20

14.84

21.05

30.67

48.60

1 40.00

45 0.00

50

0.00

3.84

7.95

12.58

18.24

26.06

37.65

, 59.90

2 3. .30

50 0.00

55

0.00

4.66

9.62

15.23

22.14

31.45

45.70

1 12.50

2 29.20

55 0.00

1 0

0.00

5.54

11.43

18.15

26.34

37.45

, 54.30

1 26.40

2 57.80

60 0.00

1 10

0.00 7.54

15.55

24.68

35.88 50.90

1 13.90

2 9.10

4 1.54

70 0.00

By means of this Table, Logarithmic Tables to five places of decimals^
such as Lalande's, may be employed in Trigonometrical Surveying.

( 173 )

Notice irf an erroneous Method of using the Theodolite^ with a
strict Analysis of the edicts (if variouH arrangements ivf
Readers, By Mr Edward Sang, F.R.S. E., M.S. A.,
Civil-Engineer and Machine-maker, Edinburgh. Commu-
nicated by the Society of Arts.*

Some months ago, while conversing on the subject of theodo-
lites with a gentleman who had been engaged in the Ordnance
Survey, I learned that a peculiar arrangement of the readers
exists in some of the instruments used therein ; and that a still
more peculiar method of determining their average indication is
employed.

On immediately expressing my opinion that the method is
erroneous, a discussion ensued, in the course of which my in-
formant reiterated his statements in terms sufficiently explicit
to remove all doubt as to his exact meaning. I have since been
told that this description applies to the Great Theodolite ; in
which c^se the minute accuracy of the survey must rest on very '
insufficient data, since the impropriety of this method must af-
fect every observation of horizontal angles.

This accidental circumstance has led me to develope at
greater length an analysis which had been sketched out, on the
occasion of my report concerning Mr Galbraith"'s pocket re-
flecting circle. This analysis I now beg to offer to the atten-
tion of the Society of Arts, and also to that of the Ordnance
surveyors, in the hope that it may lead to a definite knowledge
of the powers of various methods of reading, and that it may
help to remove that blind reliance on the authority of names
which is too prevalent. Should my information prove to have
been incorrect, my labour will not therefore have been in vain,
since my object is to exhibit what is accurate in principle ; and
should my information prove to have been correct, a strict de-
monstration of the impropriety of the process may lead to its
rejection, and may thus free the rest of the survey from its in-
jurious effects. It is proper to mention, that the errors arising
from this source are not of that class which would visibly affect
the maps of counties, or the acres of parishes ; they are, how-

Read before the Society of Arts for Scotland, 28th November 1838.

174} Mr Sang on an erroneous Method

ever, of an order sufficiently high to induce inaccuracies in the
determination of the degree of the meridian, the oblateness of
the earth, and such hke.

The arrangement of the readers, as described to me, is this :

A

A, being the principal one, another, B, is placed exactly oppo-
site to it, so that the two, A and B, form the ordinary system
of two readers. Again, two others, C and D, are placed each
120° from A, so that the three A, C, D, form the common
system of three readers. ^

The indications of these four having been taken, the average
of A and B is struck ; also that of A, C, and D ; and lastly,
the mean of these two averages is taken for the true reading.

Putting a, 6, c, d for the four readings, this unique opera-
tion is thus represented in an algebraic form :

a -\- b g + c 4- c?

2

which is equivalent to

12

The evils of the method stand so prominently forward in this
expression, that there is hardly need for saying another word
on the subject. Yet it may be better to inquire into the real
amount of imperfection than merely to point out its source.

If our instruments were perfectly graduated, and accurately
centred, one reader would be as good as two, three, or five, for
the readings by all would be exactly alike, and their average
the same as any one. Headers are multiplied for the sake of
correcting the error of excentricity, and of diminishing that of
graduation. Now, the error of centering is eliminated from

^—x — , and also from - — ^ , so that it is necessarily corrected

of using the Theodolite. 175

in their average. The excentricity, then, has no connection
with the faults or advantages of this singular method ; these
can have reference only to erroneous graduation.

Viewing the matter in this light, it is perfectly obvious that
more confidence is placed in the reading at A, than in that at
B in the ratio of 5 : 3, than in either of the readings at C and D
in the ratio of 5 : 2. The meaning of this would easily be un-
derstood, if it were known that the limb towards A is more
trustworthy than that towards B ; but then, unfortunately, this
best part of the limb would need the property of ubiquity,
since it must change place every time the telescope is directed
to a new signal !

In my report to the Society on the merits of Mr Galbraith^s
reflecting circle, I shewed that the correction of errors by many
readers is a matter of probability only ; «.and it follows that the
more numerous the readers are, so much is the chance of exac-
titude increased. Let us compute the relative inaccuracies of
different systems of verniers applied to a given limb.

Let us conceive a perfect set of divisions to accompany the
actual ones. The distance from any perfect division to the
corresponding imperfect one, will be the error of the last :
n being the entire number of divisions, put p, q^ r, *, ^, &c. for
a few of the errors ; the sum of these, /? H- ^ + r -f &c., being,
as usual, denoted by 2/?. It would at first sight appear, that

the Tjth part of this, that is - 2;?, is the average error to be ex-
pected from the graduation. This, however, is not the case;
for we may imagine the whole system of exact divisions shifted
round a little, so as to increase or to diminish all the errors

equally. The average -2/? thus depends upon the arbitrary
position of the normal divisions, as well as on the actual gradua-
tion. Indeed, that position may be so assumed, as to render
this average zero. For this purpose, we have only to shift the

normal system forward by a distance - 2 p. The different er-
rors would then be

1 1

of which the sum is evidently zero. That is, if this method of
averaging the error were allowable, the mean error in all in-

176 jNIr Sang on an erroneous Method

struments would be zero. In order to obtain a measure of the
inaccurac)^, we must average the squares of the errors: this
average never can be zero unless the divisions be absolutely
perfect. The sum of the squares of the errors also depends on
the arbitrary position of the normal system ; and it is clearly
fair so to choose this, as that the measure of inaccuracy be the
least possible. This occurs when the sum of the errors is zero.
Assume, then, the position of the system of exact divisions,
so that 2/? = o : /?'^ 4- 2''^ + r^ 4- &c. or 2 .p* will be the mea-
sure of entire inaccuracy, and - 2 ;?^ that of the mean inaccuracy

to be expected from a single observation ; representing this
expectation by {e^Y^ we have

The value of this expression depends on the peculiarity of
division, and can only be ascertained for each instrument by
direct experiment.

We have now to inquire what is the probable error from an
observation with two readers. The errors of the two readings

being p and g, that of their mean must be ^-^-^; therefore,
supposing the errors to be scattered by chance round the limb,
4- 2 . (/? + 9)^ is the entire measure of inaccuracy arising from
double reading. This may be put under the form

in which p^ will occur 2 {n — 1) times, ^ pq twice ; hence the

total inaccuracy is ~ 2.p^-f2p^. Here I observe, that

-|^2.p^-|-2/?^ = ^ {2pY = o ; so that the measure of entire

inaccuracy is -^—2/?^. Now, the entire number of chances is

n{7i — 1), hence the measure of inaccuracy on the double
reading is

^/ n n — 12 ^
n — \ 2 v^'^

of using the Theodolite. 1T7

In this formula, n is always a very large number, so that the
fraction ,- is almost unit ; and thus

\ = ^1 ^\ "^^^y-

When the system of three readers is used, the error is of the
form

3

and thus the entire measure of inexactitude is

which may be expanded into

in which jo' will occur in each of the three situations (n — 1)
{n — 2) times, that is in all 3 (n — 1) (?* — 2) times; while
2;? gr will occur in each place 2 {ii — 2) times. We have, then,
for the entire measure of inaccuracy

i {3(«-l) («-2) 2/>'^ + 12 (m-2) 2i>(?}
and for the measure of one chance

that is {e f

3 n(n — l)
1 » — 3 1 .

(« — 3)2.^«

s'' ?t n — 1 3

_ 1 !izi2 (e Y

whence e, = e — - — -

^ 1 \f 3 n — 1

Putting, in general, i for the number of readers, the form of
one error is

p + q-i-r-i- (» tenns)

«

and hence the measure of inaccuracy of an ohservation with t

readers is

(eY - 2 . {jt> + g -f r 4- i terms}*

^ '^ ■" i«.M(» — 1)(» — 2) (n — »+l)

VOL. XXVI. NO. LI. — JAIJUABY 1839. M

178 Mr Sang on an erroneous Method

the integral of which may be put

2. {i?^ + 2^3'4-2jt)r4- (i—1) terms

-{- q^ 4-2g'r+ (i — 2) terms

+ r^ 4- (i— 3) terms}.

p^ will occur in each place; (w — 1) (/i — 2) (n — i + 1)

times, or altogether i{n — 1) (n — 9) (n — i + 1) times;

while 2/?^ will occur in each place 9.{n — 9){n — 3)

{n — i + 1) times; but the number of places is — 2~"' ^^"^^
altogether we have

^'^ in{n—\)

1 1 n — i

= 2 'P^

inn — 1

1 n

and thus we have this general proposition, that the square of
the expected error is proportional to the number of points not
examined, divided by the number of those actually compared
with the readers; and hence, in the extreme case, when every
division has been examined, the chance of error is reduced to
2ero.

I shall now seek the value of the chance given by the me-
thod of reading which is above described. In this method, the
readings of particular micrometers are multiplied by certain
arbitrary numbers : the solution of the general question pre-
sents some interesting points.

Let a, /S, 7, 3, &c. be the arbitrary coefficients of the read-
ings; an error will take the form

ccp + ^q + yr + "^S + &C.

and hence the squares of the errors will give the sum

( — ) S. [a p + (i q + yr + ^ s + etc.y =

( — ) S.{a2p2^2 a(ipq'{'2aypr + etc.

+ (iq^ + 2fiyq7'+ etc.

+ yr^ + etc. }

In this sum, supposing the arrangement of a, /3, 7, &c. un-
changed, the errors p, q, r must be permuted in every pos-

of using tJte Theodolite, 179

sible way ; let i be the number of readers, a- p* will occur

(n — 1) (n — 2) (n — J3) (m — i + 1) times, Vfh\\e2a^pq

will occur 2 (n — 2) (n — 3) (n — i + 1) times; hence the

entire sum is

(»— 2)(n— 3) (n—i+l) {(«— 1)2««. 2^«4- 4 2«/5.2/)9}

and thus

VS^/ n(»-.l) n(»— 1) (2«)«

In our case a = 5, /3 = 3, 7=:2, 6 = 2, 4 = 4; hence

^^^ - 24». 7n-7 ^^

24 7» — 7 ^ ^^
that is, since w is a very large number, the measure of inaccu-
racy by this method is ^ of that by one reading. Now had

the four readers been arrang^ at 90° apart, and their simple
average taken, the measure of inaccuracy would have been

^ or 24, so that g part is added to the chance of error by* this

improper arrangement ; while the labour of averaging is much
increased.

It is well known, however, that an observation with the
theodolite is only complete when the telescope has been reversed
in its V*s, and the readings again taken. Let us then seek for
the measures of inaccuracy of the different arrangements of
readers, supposing the reversion to be used. If the readers be
so arranged that, on reversion, they come opposite new portions
of the limb, the chance of error will be diminished one-half;
but if their number be even, the chance of correcting the errors
of graduation is only improved if they be unsymmetrically ar-
ranged. It is then highly improper to have an even number of
readers uniformly distributed ; for example, if we have four,

the error on reversion is | (e^y ; while if three verniers only had

been used, the chance of error would have been diminished to

6 (^i)* ' ^^^ errors of collimation and verticality being corrected

1 80 Mr Sans: 07i an erroneous Method

•&

in both cases. What is the efFect" of our peculiar mode of ar-
rangement ? On reversion, the two readers A and B merely
change places, but C and D go to new parts of the limb. The

average then takes the form

-

that is, four times as much importance is attached to each of
the readings at A and at B as to any of those at the other
points ! !

Applying the general formula to this case, we have
« = 4, ^ = 4, y = 1 , 5 = 1, s = 1, ^ = 1, i = 6
and

That is to say, just as much precision (in correcting the inequa-
lities of the limb) is obtained by eight readings as might have
been had from four, and the reversion, instead of doubling the
exactitude, has only reduced the chance of error from oi ^^ ok •

Nay more, if the reader B had been entirely left out, the pre-
cision w^ould have been augmented, the chance of error being

then only 24. •

Thus the surveyor has added greatly to his field and house
labour, and has enormously complicated his operations in order

to augment the chance of error from g to ^ !

Here it may be worth while to inquire, what values should
be given to the arbitrary coefficients a, /3, 7, &c., in order to
render the determination as exact as possible. In the formula

if we suppose 2 a to be constant, we must seek so to divide it
as to render the sum of the squares of its parts a minimum ;

this gives cc=z(3=d — — -r-, that is to say, the best value

for a, /3, 7 is unit, and therefore we have here a complete de-
monstration of the impropriety of regarding one reading more
favourably than another. Some crude ideas concerning the
superiority of one reader over another have been urged in sup-

of using the ThcodolUe, 181

port of the method under review ; but it is quite obvious that
the circumstance of one term being measured with extra pre-
cision, does not entitle it to be counted several times in striking
the mean.

From the preceding investigation, we can easily discover
what is the proper arrangement of readers. In the first place,
all the readings must be regarded as equally entitled to atten-
tion, so that their simple average must be taken. In the second
place, the reversion of the telescope must not cause any. two of
them to exchange places ; and thirdly, the error of excentricity
must be corrected. Now the error arising from the excentricity
is a function of the sum of perpendiculars let fall upon lines
touching the limb at the readers ; while there is this property of
equilateral polygons, that the sum of perpendiculars let fall upon
their sides is the same from whatever point they may proceed ;
so that, if the readers be uniformly arranged around the limb,
the error arising from excentricity must be constant, and there-
fore must be eliminated from each observation. On the whole,
then, it is best to have an odd number of readers disposed uni-
formly around the circle.

Mere opinion has too long held the place of accurate study
in the construction of angular instruments. In particular, the
question whether the method of repetition, or that of frequent
readings, be preferable, has been discussed with almost national
warmth. Repeated observations are French, single observa-
tions are English, as if there be national scientific creeds. Let
us inquire, by help of the same strict analysis, which of the two
gives the greatest probability of precision.

The errors of excentncity and of collimation need not be
counted, since these are guarded against in a proper observa-
tion according to either metliod. The errors of graduation
and of fixing alone remain to be considered. Let the expecta-
tion of error on one observation with all the readers, and with
reversion, be E, that on the last repeated arc is just E ; so that

if A; be the number of repetitions, | is the expectation of error

on the result ; whereas if k single observations had been made,

the expectation of error would have been -E^. An example

will shew the matter in a clear light. Suppose an instrument

182 Prof. Nepomuk Fuchs' Chemical Views regarding

with three readers be used nine times, first by the method of
single observation and then by that of repetition. The first
method would require 108 readings, and would give a probable

inaccuracy of —~r= • The second would need only 12 readings,

and would give an inaccuracy of ■ /— , that is, with one-ninth

of the labour in reading, just three times the degree of exacti-
tude. So much for the error of graduation. As for that of
fixing, the clamp is more frequently needed in the operation of
frequent single readings than in that of repetition ; and thus
the latter has here also the decided advantage. In neither case
can the precision go beyond what the telescope is capable of
exhibiting.

We must not, on this account, suppose that the relative merits
of a French repeating theodolite and an English single one are
settled ; but this I think is quite determined by the investiga-
tion that the same instrument is capable of giving much better
results by the method of repetition than by that of single ob-
servation.

Chemical Views regarding the Formation ofRochs, which seem
to afford new arguments injavour of' Neptunism. By Pro-
fessor and Mining Director Nepomuk Fuchs of Munich.';

It is now admitted that Werner ascribed by much too great
an influence to the agency of water. The minerals of which
the greatest mountain masses are composed, are either insoluble
in water, or soluble in so slight a degree, that in order to dis-
solve them, a much larger mass of water would be requisite
than at present exists on the earth. Were we to assume that
every thing ha i been dissolved in water, it could hardly be pos-
sible to explain how the compound mountain-rocks, such as
granite, could have resulted from aqueous solution by means of
gradual crystallization. As the different minerals contained in
the mixture possess different degrees of solubility, and of the
power of crystallizing, they should not necessarily have been de-
posited in strata, and they could not, under certain relations, have

the Formation of Rocks. 183

increased their dimensions beside, and over one another, in all
directions. We have also to take into consideration the quan-
tity of water which must have been required for the solution,
and of which we are totally ignorant as to where it has gone^
unless we adopt the idea to which Werner was inclined, that
the largest portion of it has been transported to another heavenly
body.

On the other hand, there are important arguments opposed to
the Plutonic theory. Such, for example, is the behaviour in the
fireof those mineralswhich constitute the component partsof Plu-
tonic mountain- rocks. How are we to explain the occurrence
of various minerals in compound stony masses, when we find
easily or difficultly fusible, or apparently infusible substances,
not only lying next one another, but very frequently imbedded
in, or penetrating one another, so that their simultaneous origin
cannot be doubted ? How is such a relation to be explained
if the whole had been melted together into a homogeneous
mass ? It is true that, in furnaces, crystals resembling minerals
have been formed, but a compound like granite has never been
thus produced. Had granite been fused, the quartz would have
crystallized first of all, and long afterwards the crystals of fel-
spar and mica would have been formed, according to the very
different degrees of fusibility and solidifying power of these
three substances. But how, under these circumstances, could
they have been blended with one another as we now find them,
and as they also occur with other minerals, which are partly
more refractory than quartz, and partly more easily fusible than
felspar and mica ? In my opinion, this is altogether impos-
sible ; and, on this circumstance alone, apart from all other
grounds of objection, I think that the elevation theory must be
regarded as untenable. To this is also to be added the consi-
deration, that, in granite and similar rocks, no trace has hither-
to been found of a vitreous substance, which we sliould expect
if they were products of fire.

What stood chiefly in the way of the Neptunian theory, was
the assumption that all rocks had been dissolved in water, a
supposition which cannot be conceded by chemistry. This opi-
nion found support, more especially in the crystalline nature of
the mountain-rocks, and particularly of the older ones, which

184 Prof. Nepomuk Fuchs' Chemical Views regarding

it was thought could not be explained in any other way than
by a previous solution. But such an assumption is by no means
necessary, for we know that bodies can crystallize without being
dissolved, or being in a liquid state. On this subject, I would
refer to my Essay on the Amorphism of Solid Bodies (" uher
den Amorphismus Jester kdrper''^), in which I have shewn that not
only liquid bodies, but also such as are in an amorphous (formless)
solid state, are capable of crystallization.* The passage of such
amorphous masses into crystalline ones, takes place more par-
ticularly when they are under water, and are in a semi-solid or
pasty (Jestweich) condition. In passing, however, from sucli
a condition into a crystalline one, they diminish considerably
in bulk. Accordingly, it is by no means necessary that all
crystalline bodies should have been previously in a liquid con-
dition, although they must all have been in an amorphous state.
From these views, I would deduce the following application to
the formation of mountain masses. At first the earth, by means
of water, was partly in a semi- solid or pasty, partly in a liquid
or dissolved condition. The question first to be answered is,
"What was dissolved, and what was solid, and only penetrated
by water ? A knowledge of the exact constituents of mountain
masses facilitates the answer. Two acids, viz. Silicic acid (ge-
nerally termed silica) and carbonic acid, at once present them-
selves as the most important component ingredients. The
former formed the insoluble portion of mountain masses, either
vmcombined as a gelatinous substance, or united with such bases
as alumina, potash, magnesia, the oxides of iron, &c. A large
portion of this acid was also dissolved in water, as is still ex-
emplified in springs. The carbonic acid appropriated to itself
the lime and a large quantity of the magnesia, and formed the
principal mass of the dissolved portion. It is not necessary
at present to attend to what was dissolved besides ; but I may
remark, that it could consist of nothing but matter which har-
monized with the calcareous solution. But, as the neutral car-
bonate of lime which occurs in nature, is not at all, or very
slightly soluble in water, and only becomes soluble when an

* Our Author's Memoir on the Amorphism of Solid Bodies, will be found
in vol. xviii. p. 263, of this Journal.

the Formation of Rocks, 185

excess of carbonic acid comes into play, a much larger amount
of this acid must have existed than is now contained in our
calcareous rocks. Such is my idea regarding the original or
chaotic state of the earth. If another condition preceded that
one, it must, nevertheless, have changed to the latter before the
formation of our mountain masses could have had its commence-
ment.

The atmosphere at that time probably consisted entirely of
nitrogen, carbonic acid gas, and watery vapour ; oxygen did
not exist, because it was not necessary. Accordingly, from the
beginning, a beautiful internal order of events was arranged in
creation, according to which, in conformity with chemical laws,
the formation of substances that pervade all periods should
proceed. I shall now touch briefly on a few of the leading
points connected with these materials. The two above-men-
tioned acids, silicic and carbonic, which mutually exclude each
other, were placed over the v/hole as governors, and each led
what was placed in subjection to it to a certain fixed result
Tlius, two great series of substances were developed, which pro-
ceeded next each other in an undisturbed manner, and which
accompanied each other in every period ; these were the silicic
acid and the carbonic acid series. The former may be termed
the siliceous, and tlie latter the calcareous series ; another is still
to be added, which does not present itself in any abundance till
a late period, viz. the carbonaceous series.

1. The Siliceous Series. — The formation of mountain masses
began with siliceous matter, and the series extends to the most
modern period. The crystallization of such large masses must
necessarily have been accompanied by unusual phenomena,
among which must be reckoned that of light. By the passage
of matter from a state devoid of form, to one of regular shape,
heat must also have been disengaged, which, when crystalliza-
tion proceeded rapidly, might have amounted to red heat, by
means of which actions similar to those of volcanos would be
produced. We can also understand the formation of com-
pound mountain-rocks, from a pasty amorphous condition of
the mass ; in which condition alone crystals can be formed,
arranged, and mixed, as we find them in granite and other
compounds. But the same did not take place simultaneously

186 Prof. Nepomuk Fuchs' Chemical Views regarding

at all points on the globe ; for while granite was formed at one
place, syenite, porphyry, mica- slate, greenstone, and quartz-
rock were formed at others. We are to regard, as varieties of
only one formation, the members of the siliceous series, that
are constantly passing into one another, and more especially
the older and compound ones ; and we may conveniently term
the whole compound members of the siliceous series granitic
rocks (ffranitartige gehilde). The waters were sometimes at
rest and sometimes agitated, and this dilFerence so influenced
the structure and external form of the mountain masses, that
some were formed without a distinct stratified structure, others
distinctly stratified, and that some had their structure more
perfectly developed, and others had it less so. The waters
must have been particularly tranquil at first, while it was, as
it were, fettered by the pasty mass. It was only after a con-
siderable portion of the latter had been crystallized, that it ac-
quired more freedom, and could be set in motion by the air.
At a more recent period it became particularly agitated and
stormy, and hence the members of the siliceous series could
not be so perfectly and distinctly developed as before. This
imperfection commences in clay-slate, a rock which is nothing
else but a granite, with very small and indistinct component
parts. In the secondary rocks, the quartz presents itself only
in small grains, which, in the course of time, became united,
so as to form sandstone. The triple combinations of silica,
alumina, potash, &c. which, in the primary period, gave rise to
the different kinds of felspar and mica, occurred in the modern
period only as a fine mud, and formed the different varieties of
clay. Mica only was frequently developed in small scales in
the modern period, while the felspar lost its characters in a
friable fine-grained mass.

Quartzose sand, sandstone, and clay very frequently, nay, al-
most generally, occur mixed with another, and in such rela-
tions, that, if circumstances had been favourable to their de-
velopment, they would very probably have afforded the most
perfect granite. Hence we may, with good reason, say, that
this mixture is the representative of granite in the modern
period ; an idea which is countenanced by the fact, that such a
mixture sometimes actually passes into well marked granite.

the Formation of Rocks. 187

It will be objected to this opinion, almost universally, that
tsand, sandstone, and clay, are nothing else but debris result-
ing from the weathering and mechanical destruction of the
older rocks, which has been washed together by water. I am
myself of the opinion, that much owes its origin to such pro-
cesses ; but I am also convinced, that a large, and indeed by
much the largest, portion of the rocks that are regarded as of
secondary* origin, have been formed in a similar way to the
older formations, and are only a continuation of them.

Let us only consider what masses must have been destroyed,
and what must have been necessary for converting these masses
into fine quartzose sand, and mud-like clay ; let us consider,
if the clay, which is included so universally, and in such large
quantity, in the newer calcareous formations, could have form-
ed a part of these, if it had been washed thither, and had not
been formed simultaneously with the limestone. This clay
not unfrequently passes into a substance resembling hornstone,
in which certainly we can see no more appearance of a mecha-
nical origin, than in the flint of the chalk formation, which be-
longs to the last members of the siliceous series, and only dif-
fers from quartz-rock, in the imperfection of its development.
The sharp edges andj angles of the grains of many sandstones
are also adverse to a secondary origin ; and even if they were
rounded, this would be by no means a conclusive proof of such
an origin, inasmuch as they might have acquired this charac-
ter during their formation in agitated water, where crystalliza-
tion was disturbed, just in the same manner as hailstones.
Portions of quartz, having quite the aspect of rolled pebbles^
sometimes occur in veins. In many sandstones no uniting
basis can be recognised, and the grains are sometimes so inti-
mately blended, that the whole mass cannot be distinguished
from some kinds of primary quartz; and the natural conclu-
sion is, that it must have been formed in the same manner as
the latter.

2. The Calcareous Series. — This series commences with the
siliceous series, in the primitive class of rocks, and constantly

* The term secondary, is here, and in another sentence, used, not to de-
signate a class of rocks, but in opposition to the term original, as exiMve-
sive of the formation of particular rocks. — Edit.

188 Prof. Nepomuk Fuchs' Chemical Views regarding'

accompanies it through all epochs, up to the newest period. In
the primitive formations, it is of inconsiderable extent, but after-
Avards increases in amount, almost in the same ratio in which
the siliceous series diminishes, and makes its appearance in the
secondary class of rocks, in masses of immeasurable extent.
Limestone is invariably of crystalline origin ; but this can
only be distinctly discovered in that of primary periods. The
newer limestones are almost always an accumulation of such
extremely small crystals, that the latter can only be recognised
under a good microscope. This structure presupposes the
])resence of this substance after the creation, in a condition in
which it could acquire such a structure. Geologists, and more
especially Vulcanists, are thus placed in great perplexity, al-
though they do not always acknowledge it. If the earth was
in a melted condition, the carbonate of lime must have been so
also ; and this, it is believed, may be assumed unconditionally,
since we know, that it can really be melted under a certain
pressure, without losing its carbonic acid. Nothing can be
said against this ; but nevertheless we must remember another
circumstance, of great consequence, and one which seems to be
forgotten by the Vulcanists, viz. that carbonate of lime and
silica cannot exist together in a strong fire, for the carbonic
acid must yield to the silica, inasmuch as a silicate of lime is
formed. Aluminous silicates, as felspar, mica, &c. act in a si-
milar manner on carbonate of lime.

If, therefore, we assume that all was at first melted to-
gether, I would ask the question, if, according to chemical laws,
carbonate of lime could have existed without being converted
into a siHcate ? Such must evidently have taken place, and
we ought, under these circumstances, to meet with hardly any
quartz or limestone in the mineral kingdom. But as this is not
the case, as silicate of lime is a rare substance, and as pri-
mitive limestone not unfrequently contains quartz, mica, fel-
spar, &c., the Vulcanists cannot be correct in their views; and
as the limestone cannot have been melted, it must have acquired
its crystalline structure in another way, viz. by means of water.

The Vulcanists admit that transition and secondary limestones
have been precipitated from water, for they are forced to do so
by the petrifactions that are contained in these rocks, and also

the Formation of Rocks. 189

by other circumstances. They regard such formations, how-
ever, merely as a mechanical sediment, and not as a chemical
precipitate from water. But, so far as I know, they do not ex-
plain whence they came. In order to be consistent, they must
admit that the transition and secondary limestones were at first
formed by fire, just as, in their opinion, the primitive limestone
was so produced, that they were then destroyed, reduced to a
powder by water, driven about for a certain period, and at last
deposited. But in this manner, we cannot account for the con-
stant increase of the masses in the newer members of this series,
without mentioning other difficulties. Here also we perceive
that the volcanic theofy leads from one perplexity into another.

There thus remains no other opinion for our adoption, but
that which maintains that all carbonate of lime was at the be-
ginning dissolved in water, by the assistance of an excess of car-
bonic acid, and that, as the excess of acid was subsequently
separated, the carbonate was precipitated more slowly, and in a
more decidedly crystalline state, in the more ancient, but more
rapidly, and less perfectly developed in the newer period.

It must here be remarked, that when carbonate of lime is se-
parated from a solution, it appears at first as a very bulky,
mud-like, and amorphous mass, that it remains for a time in
that condition, and only afterwards passes into a crystalline
powder, at which time it becomes contracted into smaller space.
But on the great scale, it could remain much longer in an amor-
phous condition, than on a small ; and, as a pasty mass, it could
bear along with it the substances mixed with it (chiefly sili-
cates), and these could crystallize freely in it.

The occurrence also of clay, and the equal distribution of
that substance and of petrifactions in certain beds of secondary
limestone, become in this matter capable of explanation. Such
phenomena could not be accounted for if the carbonate of lime
had passed directly from the liquid condition to the crystalline,
and had at the same time been rapidly precipitated.

It will, however, be asked, whence was derived the great
quantity of carbonic acid which served for the solution of the
neutral carbonate of lime ? This question does not embarrass
me, as I shall soon shew, when treating of the carbonaceous
series, to which I next proceed.

190 Prof. Nepomuk Fuchs"* Chemical Views regarding

3. Carbonaceous series. — This series, although the smallest,
is of great importance. It commences with graphite in the
primitive rocks ; and the black limestone and clay-slate, more
especially drawing slate and alum-s\ate, and the substance termed
lydian stone, attest its presence and its advancing progress.
These substances form the continuation of the carbonaceous
series in the transition class, where also anthracite makes its ap-
pearance in considerable masses. But this series acquires its
greatest development in the older rocks of the secondary class,
in the true coals ; and it ends with the varieties of brown coal
in the newest formations, if we do not regard peat as its last
member. To this series also belong the different kinds of
mineral pitch which occur in limestone, sandstone, marl, and
clay.

It is only graphite, anthracite, and diamond that are almost
universally regarded as original mineral products, and doubts
have even been entertained on the origin of these substances.
All the others are considered as strangers derived from the ve-
getable kingdom. There are many circumstances in favour of
this opinion, such as the chemical constitution of these bodies
which is similar to that of plants ; the not unfrequent occurrence
of vegetable remains, even of entire stems of trees along with
coal ; and finally, the distinct passage of wood into brown coal,
which, externally, often bears the greatest resemblance to black
coal.

But here we also meet with great difficulties. Thus, we
cannot comprehend how it happens that strata of coal so often
alternate with other strata, as of sandstone, slate-clay, &c. ; for
we can hardly suppose that each bed indicates a new vegetation.
Further, we cannot understand how the vegetable fibres have
been so completely altered, that they have not only lost their
form and all signs of organization, but have even been con-
verted into a half-liquid mass, for such a condition must have
preceded the formation of coal, inasmuch as the carbonaceous
matter could not otherwise have penetrated into the clefts and
veinJike fissures in which we sometimes, find it. These diffi-
culties have not been overlooked by geologists, and recourse
has been had to sulphuric acid, in order to obviate the last.
But, besides that this acid, although it can produce a semi-

the Formation of Rocks, 191

liquid carbonaceous mass, cannot actually form real coal, it
must be remembered that it could not have existed in a free
state along with the universally distributed carbonate of lime,
and could not therefore have operated. I am surprised that it
has occurred to no one to ask, Whence the vegetables, that are
entombed in the earth, and are converted into coal, derived their
carbon ? D'Aubuisson, so far as I know, only asks the ques-
tion, If the carbon which forms the basis of coal, is entirely de-
rived from plants, or if it cannot have had some other origin ?
The assertion that coal is derived from the vegetable kingdom,
does not solve the problem, but merely removes it to a greater
distance, exactly as is done by ascribing the origin of limestone
to shells and zoophytes. It cannot, of course, be supposed that
there was a subsequent creation of carbon for organic bodies ;
and the conversion of another substance into carbon is just as
little to be thought of; for this would just be to cut the knot,
and not to loose it.

I am of opinion, that not only the carbon of common coal, of
brown coal, and of mineral pitch, but also the carbon of all ani-
mated nature, has been derived from an excess of carbonic acid.
This acid had, from the beginning of the creation, a threefold
destination ; first, to keep the neutral carbonate of lime sepa-
rate from the silicates ; secondly, to provide the atmosphere with
oxygen ; and, thirdly, to furnish carbon to coal and to organic
bodies. Whence, otherwise, could these have obtained their
carbon, if oxygen were to be regarded as a direct creation ?
How could carbon, which alone is perfectly insoluble in water,
have been preserved, from the beginning of creation, through-
out the whole time occupied by the formation of other rocks,
until the period arrived when it was required to fulfil its pro-
per end ? Certainly in no other way but united Avith oxygen,
and in the state of carbonic acid. It is only from that acid that
carbon and all its products, as we meet with them in nature,
could be produced. We cannot say in what manner its decom-
position was accomplished, just as we are unable to account for
many processes that are going forward under our eyes ; but, in
my opinion, it is sufficient for our purpose to know that it is
decomposable, and that it is still decomposed by plants, which
derive their carbon from it. In consequence of its decomposi-

192 Prof. Nepomuk Fuchs'' Chemical Views regarding

tion, as it gave the greater part of its oxygen to the atmosphere,
two kinds of products were formed in the newer period, viz.
bituminous products, which are distinguished b}^ containing a
large quantity of hydrogen, and products of the nature of hu-
mus, which, besides hydrogen, contain also oxygen. By the
union of the two, in different proportions, the various coals
were formed. That even during the formation of the older
members of the secondary series, there was already much bitu-
men in existence, is proved by its occurrence in many limestones
of that period, which, indeed, are often quite penetrated by it.
Had it been formed at a later period, or been derived from the
vegetable kingdom, it could not possibly have penetrated into
these compact masses, and distributed itself so equally in them.
At the commencement of vegetation, there was probably a much
larger quantity of carbonic acid in the atmosphere than there
is at present ; and, as it is well known that that acid is very fa-
vourable to the growth of plants (when, as Saussure has shewn,
it does not exceed a certain amount), those colossal plants, which
exist now only in a fossil state, had ample means of growth in
a soil which was rich in humus. The vegetable kingdom may
certainly have furnished the chief materials for brown coal,
which was penetrated by mineral pitch, and at the same time
petrified by it.

That humus can be formed, not only by decomposition or
chemical treatment of organic bodies, but also in other ways, is
proved to us when we dissolve in muriatic acid iron containing
carbon (either common iron or steel) ; for not only is a humus-
like substance formed, but an oil is also produced, which has
the smell of petroleum.

But the question may be asked. If the oxygen of the air is
proportional to the united carbon of all the three kingdoms of
nature, so as to be sufficient to convert all into carbonic acid ?
I have weighed the question well, and have found that it must
be answered in the negative ; for the known beds of coal, if
they were all ignited at once, would consume all the oxygen of
the air ; and how many may still be concealed in the bosom of
the eartJi ? Therefore a large portion of the oxygen of the car-
bonic acid must have been employed for other purposes, and, as
I believe, chiefly in the formation of gypsum. This substance,

the Formation of Rocks. 193

as it is very insoluble, could not have been in its present state
originally, but probably existed as a very soluble hyposulphite of
lime, which required much oxygen, in order to become what it
now is. It may thus be explained why gypsum does not occur
in the older formations, but is of the same age as rock-salt, with
which it is frequently associated.

After this brief account of the three series, we must consider
shortly the accompanying collateral and intermediate geologi-
cal events. During the crystallization, the pasty or semi-solid
masses must have become contracted into smaller space. The
consequence of this must have been the formation of rents and
fissures into which the existing amorphous mass penetrated, and
in which it could freely crystallize ; and in this way, veins were
formed, as, for example, those of granite. In a similar manner
great caverns and empty spaces were produced ; and this gave
rise to sinkings and fallings-in, by which strata were dislocated
and had their original position altered, and acquired the appear-
ance of having been elevated. Sinkings of masses of rock also
produced valleys and ravines, besides circular hollows in which
water was collected, some of which still remain, and others
were broken through. By means of earthquakes, the falling-
in of caverns, and the bursting of lakes, huge masses of debris
were formed, which became the sport of the waters, whose
power was often combined with that of hurricanes and violent
rains. Great devastation was produced by such agencies, as-
sisted by volcanos.

During such prodigious processes as those by which the
earth and atmosphere were formed, the imponderables must
have been in very active operation; sometimes assisting in form-
ing, and sometimes in destroying, what had been already form-
ed. The electrical meteors, more especially, must have acted
with a vigour and power, of which no conception can be ob-
tained from their present displays. Since, even at present,
lightning sometimes shatters rocks, and melts quartzose sand,
we may believe that, at such a time, the electrical masses of
fire descending from the heavens, may have vitrified rocks, and
caused actions in the depths of the earth, of such a nature as
to lead to the belief that they were produced by subterranean
fire. Since, even at the present day, water-spouts uproot the

VOL. XXVI. NO. LI.— .JANUARY 1838. N

194 Dr Graham''s List of Rare Plants.

strongest trees, and remove them far from their original situa-
tions; we may conceive water-spouts, of the period we have
been discussing, powerful enough to remove large fragments of
rock from their beds, and to convey them to remote regions,
where we are now surprised to find such strangers. I would
here make the general remark, that we ought not to judge of
the scale on which such operations proceeded at these early pe-
riods of the world's history, from what we observe now taking
place on the surface of our globe. But I do not assert that all
foreign blocks have been transported by the agency of water-
spouts ; many other causes may have brought them to their
present situations. (Compiled and curtailed from " Leonharcts
Jahrhuch^'' and the Munich " Gelehrte Anzeigen,'''')

Description of several New or Rare Plants which have lately
Flowered in the Neighbourhood of Edinburgh, chiefly in the
Royal Botanic Garden. By Dr Graham, Prof of Botany.

lO^A Dec. 1838.
Chorizema Dicksonii.

C. Dicksonii ; caule fniticoso, erecto ; foliis sparsis, lanceolatis, subci-
liatis, mucronatis, subrecurvis, titrinque subpilosis ; racemis foliis
oppositis, spicatis ; calyce pills nigris, et albidis longioribus, vestitis.
Description. — Shruh erect, branched, slender, twigs ascending, green,
hairy, and sprinkled with small darker green spots. Leaves lanceolate,
spreading or reflected, ciliated, and having generally on both surfaces a
few long spreading hairs, mucronate, without stipules, shortly petiolate.
Racemes opposite to the leaves, spicate ; pedicels cernuous, solitary in
the axils of subulate deciduous bractese. Flowers few on each raceme,
collected near the apex, large and handsome, orange-red. Calyx 2-la-
biate, somewhat attenuated at the base, on the outside as well as the
pedicels and rachis hairy, the hairs being partly long, white, and
spreading, partly short, adpressed, and black, on the inside purple, and
less hairy ; upper lip bifid, the lobes diverging and broad ; lower lip tri-
partite, the segments lanceolato-subulate, reflected. Petals inserted
near the base of the calyx ; vexillum large, semi-orbicular, reflected,
notched, of nearly uniform red-orange on both sides, and towards the
keel with an oblong yellow spot, which is rather longer than the up-
per lip of the calyx ; also spathulato-elliptical, redder and darker than
the vexillum, connivent along the upper edge and at the apex, pitted
on the outside, and having a corresponding blunt tooth within ; keel
subacute, covered by the also, inflated, its petals agglutinated from the
apex to the claws, which are linear, and distant. tStamens included in
the keel, ten, free ; anthers small, yellow, erect, bursting in front.
Pistil about the same length as the stamens ; stigma slightly pointed ;
style flat, with a dense tuft of short white hairs immediately below the
Stigma on its outer side, and a small hook above ; germen stipitate,
closely covered with ratlver long adpressed hairs, colourless and silky
on the sides, black at both sutures. Omles numerous (about ten).

Dr Gmhani''s List of Rare Plants. 105

This very handsome pUint was raised from seeds obtained by Messrs
James Dickson and Sons, Edinburgh, from Swan River, and flowered
for the first time in their nursery garden in May 1838.

Collinsia heterophylla.

C. hcterophylla ; foliis inferioribus trilobatis, superioribus ovTito acumi-
uatis ; pedunculo floribus breviore ; calycibus glanduloso-pubescen-
tibus ; kiciniis corolla? apice rotundatis, creuatis, lobo medio labio-
runi inferiorum subacuto, labio superiore fauce subintegro.
Colluisia heterophylla, Buist, MS. — Grah. in Bot. Mag. 3695.
Description. — J?oof annual. Stem erect; branches divaricated, ascend-
ing, slightly pubescent when young. Leaves glabrous, distantly serrated,
paier below, darker above, lower ones 3-lobed, and petiolate, the upper
ovate, subsessile. Bractece opposite, lanceolato-linear. Flowers large and
handsome, very much resembling those of C. hicolor, to which it is cer-
tainly nearly allied, the lower opposite and solitary, the upper in crowd-
ed whorls. Calyx, like the common peduncle, glanduloso-pubescent on
the outside, coarsely hairy within, ventricose at its base, its rather short
blunt segments spreading. Corolla (gths of an inch long, above an inch
across in its longest diameter), with a few long hairs scattered over
the upper surface, slightly glanduloso-pubescent on the lower, the in-
side of the tube having long coarse hairs ; the lobes of the upper lip,
and the lateral lobes of the lower lip, rounded and crenate in the apex,
the central lobes straight and subacute, the prominent ridge projecting
into the throat from the upper lip subentire ; the colour of the flower
is deep lilac over the whole of the lateral lobes, except at the throat,
at the tip of the middle lobe, and at the tip and base of the upper lip,
every where else the flower is white, but in front of the upper lip the
white portion is sprinkled with lilac spots. Fertile stamens about as
long as the middle lobs of the lower lip ; filaments hairy along their
upper side ; anthers orbiculato-kidney-shaped, orange, bursting along
the edge, abortive stamen subvdate, green, without appearance of an-
ther. Pistil glabrous ; stigma minute ; style much declined ; germen
green, ovate.
Tliis, the handsomest species of Collinsia yet known, was found by Nxittall
on the Columbia, and was raised at the Experimental Garden, Edin-
burgh, by Mr James Macnab, from seeds transmitted to him imder
the name adopted, by Mr Buist of Philadelphia in spring last. From
CoUinsia grandifiora our plant is easily distinguished by its pubescent fi-
laments and calyx ; from C. parriflora and verna by its short peduncles ;
and from C. bicolor I have attempted to distinguish it, by its lobate
lower leaves, by the coarser hairs on its calyx, by the rounded (not
retuse) crenate segments of the corolla, by the subacute middle lobe of
the lower lip, and by the nearly entire border to the upper side of the
throat. It extremely nearly resembles C. bicolor, but the flowers are
larger, and the character, which I have given, may be sufficient to
satisfy many of its being a distinct species, though, 1 confess, scarcely
sufficient to take away my doubts. I have not, however, seen modified
forms run riot among North American as among South American spe-
cies, and therefore my scepticism is less than if the genus had been
met with south of the equator. The gorgeous display of Buenos Ayres
Verbenas which the houses in the Experimental Garden at present
contain, shews, by infinity of form and shade, and minuteness of gi^a-
dation, how few are species, compared with diversity in these parti-
culars.

Edwardsia Macnabiana.

E. Macnabiana ; foliis 20-jugis, elliptico-obovatis, supra glabris, subtus
villosiusculis ; vexillo rotundato, aniplo, alis breviori, basi subcor-

nJ2

190 Dr Graham's List of Rare Plants.

dato ; caviiifio petalis hiaiitibnjy, ula longioribus, marginibus inferiori-
bus rcflexis.

Description. — A large skrnl or i;inall tree, witli brown warted bark ;
yonvg branches covered with adprosped silky nifous pubescence. Leaves
with about twenty pairs of elliptico-obovate leaflets, glabrous above, as
well as the channelled cununou petiole slightly liairy below, hairs ad-
pressed, rufous. Floirers upon tbo i>lant at the same time as the leaves,
in lateral racemes, pedicellod. (^aly.r cylindrical, abruptly, and some-
what obliquely truncated at both extremities, toothed, shortly but
densely pubescent. Corolla bright yellow ; vexillum about three times
as long as the calyx, rotund, sui)cordate at the base, somewhat shorter
than the other petals ; alse cultrato-elliptical, cordate at the base, claw
linear, bulging outwards ; keel a little longer than the wings, dipeta-
lous, petals elliptical, semicorduto on the upper side, spreading and
revolute at the lower margin, so as, in the space left between them, to
expose the stamens to their base, claws longer than those of the aloe,
and straight. Stamens as long as tlie keel ; filaments subulate, glabrous,
spreading at their apices ; anthers small. Pistil as long as the stamens ;
germen covered with silky adpressed rufous hairs, and marked exter-
nally by the numerous ovules ; style subulate, nearly straight, nearly
glabrous ; stigma minute. LegurM moniliform, 4-winged, wings ap-
proach in pairs above and below. Seeds roundish, yellowish-brown.

This very handsome plant has been many years in cultivation in the
Royal Botanic Garden, Edinburgh, having now a stem of eleven inches
in circumference. We do not know when or Avhence it was intro-
duced, and I have not observed it in any other collection. I cannot
but entertain a fear that it is a seedling variety of Edwardsia grandi-
/om, but it is in a moment distinguished from the ordinary form of this
by its subequal petals, by the Avide separation of the petals of the
keel, and by its flowering Avlien in full leaf. Every year till this one,
it had thriven well and flowered profusely upon a south wall, and lived
but did not blossom nor thrive as a standard. In last winter, memo-
rable for the ruin it effected among much more than half-hardy shrubs,
it suffered much less than Edwordsia grandiflora or E. microphylla, -plunts
of which, about the same si>ie aud age as E. Macnabiana, and on the
same wall with it, were killed to the ground ; but still it was much cut,
and it did not flower this year. Mr Macnab feels more confident than
I do of its being entitled to rank as a species, and to him, therefore,
I have dedicated it.

Gesneria elongata, var.

G. elongata, var. fruticosa, pubcscens, ramosa ; foliis oppositis, lanceo-
lato-ovatis, acuminatis, longe petiolatis, base insoqualibus, subsequa-
liter serratis, supra pubescentibus, subtus moliter tomentosis ; um-
bellis axillaribus, 4-floris, folio brevioribus ; corollis villosis, tiibu-
losis, fauce parum constvictis.
Description. — Whole plant villous. Stem (5 feet high) shrubby, much
branched, branches ascending. Leaves (^-G inches long, 1^-2^ broad)
opposite and decussating, petiolate, lanceolato-ovate, acuminate, neatly
and subequally serrated, somewhat harshly pubescent, and bright green
above, white, with soft tomcntum below. Umbels 4-flowered, villous,
shorter than the leaves, pedTinch^ shorter than the petiole, pedicels,
about two-thirds the length of the peduncles, bracteae 2, opposite, lan-
ceolate, at the subdivision of the umbel. Floicers unilateral. Calyx
with small spreading ovato-subiilato segments. Corolla {I inch, long,
h inch across) tubular, clavato-ventricose, dilated and somewhat fleshy
at its base, then contracted, and after being dilated, again slightly con-
tracted at its mouth, villous on the outside, glabrous within ; limb
spreading, lobes subequal, rounded, crenate. Stamens inserted into
the base of the corolla, and rising to the throat ; filaments pubes-
cent : anthers divaricated at the base where the connective is dilated

Dr Graham^s List of' Rare Plants. 197

cucuUate and fleshy, fiftli stamen rudi mental. Pistil pubescent, stigma
minute, tnmcated, stylo bent at its base, compressed ; germen niore
than half imbedded in the adhering calyx, and surrounded at its free
apex with live glands. Omlcs numerous and minute.
We received this plant at the Botanic Garden, Edinburgh, in September
1830 from the Messrs Young, nurserymen, Epsom, under the namr> of
G. oblongata^ perhaps by an error in the transcriber. It flowers most
freely, has a long succession of blossoms, and is therefore very desirable
in cultivati(m. It dift^ers from (r.ehnjnta of Humboldt in its much shorter
peduncles, in the more obtuse base of tlie leaves, in its less angular
branches, in the colouring of the veins and lower surface of the leaves
generally, and in the subulate segments of the calyx. In these re-
spects it more nearly agrees witii Gesturla mollis, Init from this it difl'ers,
and agrees with G. elomjata, by its 4-flowered umbel, its much shorter
pedicels, and the opposite bractejc at their origin, the length of the pe-
duncle being intermediate J)etween its state in these two species.
There are many forms of Gt'a.icrla from the tiopical parts of America,
but I cannot tliink they ought all to be considered as species. This
opinion is strengthened by the flgures and descriptions of Humboldt,
and the inspection of our present plant leads me to suspect that it may
connect together as varieties Ci'. u.uUh and 6'. elomjata.

Mirbelia angustifolia.

M. angustifolia ; foliis lanceolato-linearibus, crcnatis, inferiore, ramulis-
que adpresse pubescentibus, diviiricatis, rigide mucronatis ; floribus
in capitulo trifloro dispositis, vel (rache producto) verticello trifloro.
Description. — Shrub erect; bvanciiCK in whorls of three together, spread-
ing wide, adpressly pubescent. Leaves opposite, or in verticels of three
leaves, lanceolato-linear, with a few adjiressed hairs on their lower
side, very narrow, Avith short transverse veins, crenate, pointed with a
mucro, which becomes rigid. Floirers in 3-fiowered capitula, or by an
elongation of the common peduncle into a branch, becoming axillary
and solitary in a 3-flowered verticel, of which there are rarely two tiers.
Pedicels short, springing from the axil of a diminished leaf. Calj/x bila-
biate, as well as the pedicel pubescent, hairs adpressed, upper lip emar-
ginate, lower 3-partite, tube campanulato. (hrolla small, inserted at
the base of the calyx ; vexillum bent down at the sides, half-cylindrical
in the back, and reflected at its emarginate apex, lamina purple, exce]>t
at its rounded j)ortion, where, with the linear claw, it is yellowish-
green ; ala) as long as the vexillum, undulate, curved downwards, blunt,
approaching, but not in contact, along tlieir upper edges, spreading along
the lower, of uniform purple colour tov,'ards the apex, becoming white
or gi'eenish at the broad short tooth and narroAv claw; keel half as long
as the alae, inflected, its petals only cohei'ing in the lamina, emarginate,
the claM's linear. Fihimeuis alternately dilated. Pistil shorter than tlie
stamens, of uniform green colour, glabrous. Gennen nearly sessile, di-
vided into two cells longitudinally. St>/le curved, shorter than the
germen. Stiijnuz small, capitate.
The flowers of this plant are snuill, so that it possesses no degree of
beauty which will make it a favjurite with the florist. It seems to
me, however, a very distinct species. It was raised at the Botanic
Garden without si)ecific name, from seed received in April I83G from
New Holland, through Mr S};iers of Culcreuch, and flowered in May
1838.

Pimelia Hendersonii.

V. IleiuUrsomi; involucre tetraphyllo, foliolis ovatis, utrinque glal.ris,
ciliatis, capitulum congestum ujquantibus ; perianthii tubo dimidio
inferiore hispido, supericre t;er: ceo, foliis opx)ositis, lanceolato-lineari-
bus.

Description. — Shrub erect, bark brown, branches erccto-patcnt, gieen

198 Dr Graham's List of Rare Plants.

towards their apex. Leaves lanceolato-linear or spatlmlato-linear, gla-
brous on both sides, recurved, mucronulate, middle rib strong, with
obscure diverging veins. Capitulum terminal, hemispherical, many-
flowered, dense. Involucre 4-leaved, leafets broadly ovate, glabrous on
both sides, ciliated, as long as the Jloicers, which are rose-coloured, and
handsome. Perianth with long spreading hairs upon the lower half of
the tube, silky in the upper, segments of the limb ovate. Stamens and
pistU as in the genus. As the plant is a very rare one, and not my own
property, I only felt myself at liberty to dissect two flowers. In one
of these, from the outer edge of a capitulum, I foimd the germen bilo-
bular, and the style terminal between the lobes. It is probable, how-
ever, that this is an accidental deviation from the normal structure,
and that it will not be found common.
The species, which seems to me to be quite distinct from any one hither-
to described, must be placed between P. decussata and P. rosea. It is a
native of King George's Sound, and was raised by Messrs Eagle and
Henderson from seed sent to them by Captain Cheyne, in May 1837,
and, when about 18 inches high, and covered with flowers, was exhi-
bited in the Experimental Garden of the Caledonian Horticultural
Society in July 1838. It will be found one of the most ornamental
species of the genus.

Torenia cordifolia.

T. Cordifolia ; caule erecto, ramisque patulis glabris ; foliis petiolatis, cor-
dato-ovatis, inciso serratis, supra parce pilosis, subtus glabris ; pe-
dunculis unifloris, sub-umbellatis.

Torenia cordifolia, Roxb. Corom. PI. 2. 32. fig. 161. Ibid. Fl. Indie. 3. 95.
Pers. Synops. 2, 167- Benth. Scroph.

Corosinam, Rheed. Mai. 9. t. 68.

DESCB.IPTION. — Root annual. Stem (4-8 inches high) erect, square, acute
angled, or slightly winged, green, with spreading cilise on the angles ;
branches opposite, decussating, spreading wide, resembling the stem.
Lea/ces petiolate, cordato-ovate, simply inciso-serrate, bright green, and
distantly hairy above, paler and glabrous below, where the midrib,
and oblique, little divided veins are prominent, but channelled above.
Petioles channelled above, ciliated, shorter than the leaves. Peduncle
at first about as long as the petiole, afterwards elongated, exceeding
the leaves, 4-sided and ciliated, resembling the branches. Flowers sub-
umbellate at the extremity of the branches, arising from the axils of
leaves, which are crowded, resembling in effect an involucre. Calyx
bilabiate, the upper lip 3-toothed, the lower more deeply bifid, teeth
acute, green, ovate, with five ciliated wings, the upper wing only not
being produced in form of an acute angle along the peduncle, teeth
acute. Corolla pale lilac, one-third longer than the calyx ; tube clavate,
slightly curved downwards, glabrous ; limb bilabiate, spreading, the
upper lip crenate, slightly emarginate, the lower tripartite, the lobes
rounded. Stamens four, didynamous, shorter than the upper lip ; fila-
ments arched laterally ; anther-lobes divaricating. Pistil as long as the
longer stamens ; stigma bilabiate, lobes spreading, hairy upon their inner
surface ; style compressed, enlarging upwards, germen green ovato-
conical, furrowed on each side, placed on a small thin light coloured
disk, which is broadest on the upper side ; ovules very numerous, fixed
to large central placenta). Capsule bivalvular, bilocular, shorter than
the persisting calyx, with which it is covered.
This little annual, which, as we learn from Roxburgh, is a rare native of
the moist pastures about Samulcottah, in the northern Circars, flower-
ing in the dry season, blossomed in the stove of the Royal Botanic
G«urden, Edinburgh, in October and beginning of November 1838. We
received the seeds from my friend Dr Falconer at Saharunpoor, but
whether collected in that neighbourhood I cannot say j if so, it has a
wider geographical range than was supposed.

( 199 )

Report of the Committee appointed hy the Society of Arts for
Scotland, to award Prizes for Communications read and ex^
hibited during Session 1837-38.

Your Committee having met, and carefully considered the
various Communications laid before the Society during Session
1837-8, beg leave to Report that they have awarded the fol-
io ^\ing Prizes : —

1. To Mr Edward Sang, F.R.S.E., — Civil Engineer and Machine

Maker, Edinburgh, for a Notice of a Dioptric Light erected at
Kirkaldy ; with a Description and Drawings of the Apparatus
used by him for cutting the Annular Lens to the true optical
figure ; — read, and the apparatus exhibited, 25th April 1 838 : —
printed in the Society's Transactions, 1838."* (552.)

The Keith Medal, value Twenty Sovereigns.

2. To Mr James Whitelaw, 1 8 Russell Street, Glasgow, for a

Description, with Drawings, of a Grinding Machine, which is
used instead of a Turning-lathe for giving a truly cylindrical
form to the rims of Pulleys and Drums ; and more particularly
for a Drawing and Description of a Machine invented by him
for grinding Pulleys round on the rim; — ^read and exhibited 14th
February 1838; — and printed in the Society's Transactions,
1838.t (512.)

The Societi/s Silver Medal, value Ten Sovereigns.

3. To John Alston, Esq. Hon. M. S. A. Honorary Treasurer to

the Glasgow Asylum for the Blind, for Specimens of a series
of Fables, with Woodcut Illustrations, then in progress of being
printed by him for the use of the Blind at Glasgow ; exhibited
30th May 1838, (568.):— Also for his Musical Catechism, with
Tunes for the use of the Bhnd, printed in raised Characters at
the Glasgow Blind Asylum ;— exhibited l6th May 1838, (559.);
— and, generally, for his zealous, energetic, and benevolent exer-
tions for the education of the Blind.

The Society's Silver Medal, or a piece of Plate, value Ten,
Sovereigns.

4. To Mr George Wilson, 77 Broughton Street, Edinburgh, for his

Model sent in competition for the Prize offered for " a conve-
nient and simple method of increasing or diminishing the dis-
tance of the Floats from the centre of the common Paddle-
wheels, during the motion of the Vessel, so as to adapt them to

* Vide also Edin. New Phil. Journal, vol. xxv. p. 249. t Ibid. p. 336#

SOO Report of the Committee of the Society of Arts.

change in the load and draft of water ;" exhibited 30th May

1838 (524.) Although the Society do not hold any of the

competing Papers on this subject as altogether attaining the ob-
ject proposed in offering the Prize, or that they would be justi-
fied in recommending any of the proposed Plans to be adopted
in practice ; yet the Committee have awarded a Prize to Mr
Wilson for his ingenious Model, and as a reward for the mecha-
nical contrivance it displays.

The Society's Silver Medal, value Five Sovereigns*

5. To Mr John T. Rose, 1 Prince Regent Street, North Leith, for

the ingenuity displayed in his communication on the same sub-
ject;— read 30th May 1838; and to encourage him to persevere
in mechanical pursuits. (538.)

Tlie Society's Honorary Silver lledal.

6. To Mr Robert Mudie, late of 14 Fountainbridge, Edinburgh,

now in Australia, for the ingenuity and attention to the subject
displayed by him in his Drawing and Description sent in com •
petition for the Prize offered for " a convenient mode of filling
the Boilers of Steam-Vessels with water, while the Vessel is at
rest, so as to remove a frequent cause of explosion;" — read and
exhibited 11th April 1838. (509-)

The Society's Honorary Silver Medal.

7. To Mr John T. Rose, 1 Prince Regent Street, North Leith, for

the ingenuity displayed by him in a communication on the same
subject, of which the Drawing and Description were read and ex-
hibited ] 1th April 1838. (537.)
The Society's Honorary Silver Medal.
N. B. With regard to these two Plans, the Report of the
Committee to whom they were remitted states, " Mr Mu-
die's appears fully the better, but both are so complicated,
that your Committee cannot recommend them for adop-
tion ; at the same time, they think that the ingenuity and
attention to the subject displayed by these gentlemen (both
young men) is deserving of the favourable consideration of
the Society."

8. To William Alexander, Esq. W.[S.,^ M. S. A., Edinburgh,
for his ingenious Model and Description of his Electro- Magnetic
Telegraph ; — read and exhibited 15th November 1837. (489).

The Society's Honorary Silver Medal.
The Committee have awarded an Honorary Medal to^Mr
Alexander for the ingenuity ^displayed in^the construction

Report of the Committee of the Society of Arts. 201

of the Working Model of the Telegraph exhibited by him,
and for being the first person who, in Scotland, brought for-
ward the subject in a tangible form.
9. To MuNGO Ponton, Esq. F.R.S.E., late V.P.S. A.,— for the
ingenuity displayed by him in the Model and Description of his
Improved Electric Telegraph ; — read and exhibited 10th Janu-
ary and 20th June 1838, when Mr Ponton presented his elegant
Model to the Society, to be placed in their Museum. (492.)
The Society's Honorary Silver Medal.

10. To John Scott Russell, M.A., F.R.S.E., and V.P.S.A.,
for Drawings and Description of the best Method of Constructing
the Interior of Buildings intended for the accommodation of
Auditors and Spectators, and its application to Lecture Rooms,
Churches, and Music Rooms ; by arranging the seating accord-
ing to certain Isacoustic andlseidomal Curves ; — read l6th May
1838, (542), and ordered to be printed in the Transactions.

The Society's Honorary Silver Medal.

11. To Charles Heath Wilson, Esq. R.I. A. Assoc. Royal Scot.
Acad., 8 Northumberland Street, Edinburgh, for his Essay on
the Expediency of forming National Establishments for Mould-
ing and Casting Works of Art, with Observations on the im-
provements which would result from the adoption of such a
measure ;— read 28th March 1838. (555.) Printed in the So-
ciety's Transactions 1838.*

The Society's Honorary Silver Medal,
Your Committee beg leave to report, that there has been no com-
petition for the following Prizes :

2d Prize, Society's Silver Medal value Ten Sovereigns.
3d Do. Five

6th Do. — ^^ Five

11th Do. The Society's Honorary Silver Medal.
Before concluding their Report, your Committee beg to propose,
that, — while Thanks are due to all those Gentlemen who have sent
Communications to the Society, — the special Thanks of the Society
should be given to the following Gentlemen for their respective Com-
munications, viz. : —
1. To Robert Bald, Esq. F.R.S.E. Mining Engineer, Edinburgh^
for his Plan for Feeding Marine Steam-Engine Boilers with
Water;— exhibited 11th Aprill 838, (549.) which the Com-

• Vide also Edin. New Phil. Journal, vol. xxv. p. 28.

S02 Report of the Committee of the Society of Arts.

mittee reported " to possess all the advantages of the other plans,
and none of the complication, and that it could be used with ad-
vantage, only it is not a self-acting feeder, as it requires the at-
tention of the engineer — but it is exceedingly simple." This
Communication was not a competing one.

2. To John Scott Russell, M.A., F.R.S.E-f V.P.S.A., for his

Communication on the same subject; — read 11th April 1838;
(543.) —which was almost identical with the preceding, and of
which the Committee reported in equally favourable terms.
This Communication, also, was not a competing one.

3. To William Galbraith, M.A., C.S.A., Teacher of Mathe-
matics, Edinburgh, for his Communication on a Formula to ob-
tain the Decrease of Temperature according to the Height above
the Earth's Surface ;— read 11th April 1838. (546.)

4. To Mr Edward Sang, F.R.S.E., Civil Engineer, Edinburgh,
for his Essay on the Construction of Oblique Arches; with
Model and Drawings; — read and exhibited l6th May 1838, and
previous dates. (511.) Ordered to be printed in an abridged
form in the Transactions.

5. To Mr George Richardson, Printer, 35 Miller Street, Glas-
gow, for a Communication sent by him in competition for the
Prize offered " For a Method of Removing the Plaster of Paris
from the Types after Stereotyping, without injuring the Types ;"
—read 28th February 1 838. (51 6.)

The Thanks of the Society are given to Mr Richardson be-
cause he has to a certain extent succeeded ; — in so far as he
has found out a simple method of removing the Stucco ; —
but the condition of the Prize is, that this must be done
" without injuring the Types ;" now, it is found that the
Types, after having undergone his process, become, when
dry, so firmly cemented together, that they cannot be sepa-
rated except by force, which is not only attended with in-
jury to the Types, but with greater delay than the common
mode. A method of preventing the latter defect would
render his invention eminently useful.

All which is humbly reported by

DAVID MACLAGAN, Convener,

Museum of the Society of Arts,

63 Hanover Street, Edinburgh,

\Qth December \Q'SQ,

( 203 )

" Researches in Embryology T First Series. By Martin
Barry, M.D., F.R.S.E., Fellow of the Royal College
of Physicians in Edinburgh.

This paper, lately read before the Royal Society, is divided into two
parts. In the first part the author describes the origin and structure of
the ovisac, a vesicle common to all vertcbrated animals, but hitherto re-
garded as the inner membrane of the " folliculus Graafianus" in Mammalia,
and by some authors denominated tlie " chorion" in other Vertebrata.
He also describes the real nature of the " folliculus Graafianus," and its
relation to the calyx of the Bird ; tlie germinal vesicle and its contents,
as being the most primitive portion of the ovum ', the order of formation
of the several other parts of the ovarian ovum ; and the true chorion of
Mammalia as being a structure superadded within the ovary.

In the second part the author describes a granulous tunic of the ovum
of Mammalia not hitherto observed ; the manner of origin of the " mem-
brana granulosa" of authors ; the different situations of the ovum in the
Graafian vesicle at certain periods ante coitum, not hitherto observed ;
and certain structures by means of which the ovum is made to occupy
these several situations.

The following are the principal facts made known by Dr Barry in this
memoir ; but other facts are also mentioned, which he intends to make
the subject of a future communication. In Mammalia and in Birds the
germinal vesicle and its contents are those parts of the ovum which are
first formed. The germinal vesicle at an early period is surrounded by
peculiar granules, forming an envelope not hitherto described. Tlie
ovum of all vertebrated animals is contained in a vesicle (the " chorion"
of some authors, as found in Birds, Amphibia, and Fishes), which is es-
sentially the same in structure wherever found, and which he thinks it
desirable universally to denominate an ovuac. This vesicle is the
'^ couche interne" of the Graafian vesicle, as described by Professor Baer.
The Graafian vesicle of Mammalia is nothing more than an ovisac that
has acquired a covering or tunic, susceptible of becoming highly vascu-
lar, which covering is the " couche externe" of the Graafian vesicle as
described by Baer. The ovisac of Birds, Amphibia, and Fishes, (*' cho-
rion" of some authors), acquires in like manner a covering or tunic, sus-
ceptible of becoming highly vascular ; and by the union of the ovisac with
this covering, there is constituted a structure analogous to the Graafian

• Dr Martin Barry's previous obser\ation8 on Embryology having appeared
in this Journal, we judge it proper to put our readers in possession of the above
notice of his further discoveries in this important branch of Natural Historv.
Edit.

204 Dr Barry's Researdtes in Embryology.

vesicle of Mammalia. The quantity of yelk in the former beingf larg>e,
that portion of the ovary which contains the structure here referred to
(as analogous to the Graafian -vesicle of Mammals) becomes pendent;
and now the united coverings of the yelk-ball — viz. the ovisac,, its exter-
nal tunic, the ovarian stroma, and the peritoneal investment — are to-
gether called the calyx. From this it will be obvious that the Graafian
vesicle is not a structure peculiar to Mammalia, as it has been supposed.

The ovisac has at first an elliptical or ellipsoidal form, becomes more
spherical, and in Mammalia is often met with somewhat tapered at one
end. The structure of the ovisac in some of the Mammalia may be ex-
amined when it does not exceed in length the 50th or even the 100th
part of a Paris line, that is, in the latter case the 1125th of an English
inch. Myriads of ovisacs with their contents are formed that never
reach maturity. Some of the ovisacs which do not reach maturity
are situated in the parietes of Graafian vesicles in Mammalia, or of
the corresponding structures in other Vertebrata; being sometimes
formed in this situation, and sometimes included within the covering
which the larger ovisac acquires. The minute ovisacs so situated
the author proposes to denominate parasitic. The ovisac is often
found in a cavity proper to itself, with the walls of which it has no or-
ganic union. The granules forming the envelope of the germinal vesi-
cle above referred to^ and subsequently found in the fluid of the ovisac,
are very peculiar in their appearance, contain a nucleus, and sometimes
also a pellucid fluid, and are intimately connected with the evolution of
the ovum. These granules are present in largest quantity in the ovisac
of Mammalia ; yet granules essentially the same exist in an early stage
in the ovisac of Birds, and are sometimes met with in that of Fishes.

A continual disappearance of ova, and the formation of others, arc
observable even at a very early age. The ovum of Mammalia when
completely/ormed is at first situated in the centre of the ovisac. It is at
this period supported in the centre of the ovisac by an equable diffusion
of granules throughout the fluid of the latter. The ovisac about tlic
same time begins to acquire a covering or tunic, by which addition, as
already stated, there is constituted a Graafian vesicle ; and of the latter,
the ovisac is now the inner membrane. After this period, then, it is
proper to speak, not of an ovisac, but of a Graafian vesicle. The jiecu-
liar granules of the Graafian vesicle arrange themselves to form three
structures, viz. the memhrana granulosa of authors, and two structures
not hitherto described, one of which the author proposes to name tlie
tunica granulosa, and the other, which is rather an assemblage of struc-
tures than a single structure, the retinaculu. The tunica granulosa is
a spherical covering proper to the ovum, and its presence explains why
the outer line in the double contour of the thick chorion remained so
long unobserved. At a certain period this tunic, in some animals at
least, is seen to have tail-like appendages, consisting of granules similar
to its own. The retinacula consist of a central mass containing the

Dr Barry's Researches in Embryology. 205

ovum in its tunica granulosa, and of cords or Lands extending from
this central mass to the membrana granulosa. Tliese structures at a
certain period become invested by a membrane. The offices of the
retinacula appear to be, — first, to suspend the ovum in the fluid of the
Graafian vesicle, — next, to convey it to a certain part of the peripher}-
of this vesicle, — and subsequently to retain it in the latter situation,
and also to promote its expulsion from the ovary. The particular part
of the periphery of the Graafian vesicle to which the ovum is conveyed,
is uniformly that directed towards the surface of the ovary. The mass of
granules escaping with the ovum on the bursting of a Graafian vesicle
under the compressor, is composed chiefly of the tunica granulosa and
the ruptured retinacula. The " cumulus " of Professor Bacr is made up
of the parts called by Dr Barry the tunica granulosa and the central por-
tion of the retinacula ; and the band-like portions, collectively, of what
Dr Barry calls the retinacula, mainly contribute to produce the ap-
pearance denominated the " flat disc" by Professor Baer.

In Mammalia a thick and highly transparent membrane, — the true
chorion, — is formed external to the proper membrane of the yelk, while
the latter is in the ovary. The inner part of the substance of the chorion
in its early stages is in a fluid state, so that the yelk-ball moves freely in
it ; but it subsequently acquires more consistence. There is not any
structure corresponding to the chorion in the ovary of other vertebrated
animals.

The following appears to be the order of formation, as to time, of the
more permanent parts of the ovum and the Graafian vesicle in Mamma-
lia, viz. : —

1. The germinal vesicle, with its contents, and its envelope of pecu-

liar granules.

2. The proper membrane of the ovisac, which forms around this en-

velope of granules.

3. The yelk which forms around the germinal vesicle.

4. The proper membrane of the yelk, which makes its appearance

while the yelk is still in an incipient state.

5. The chorion.
The covering or tunic of the ovisac; and about the same time,

the peculiar granules of the ovisac arrange themselves to
form

<

/'The tunica granulosa.

The retinacula, and
v.The membrana granulosa.
Such of these structures as are present in the ovary of other Vertebra-
ta, appear to originate in the same order as to time.

( 206 )

NEW PUBLICATIONS.

1. Sketch of the Civil Engineering of North America. By David Steven-
son, Esq. Civil Engineer. John Weale, London 1838.

The interesting volume here recommended to the particular
notice of our readers, we owe to a son of Robert Stevenson,
Esq. the celebrated engineer. It is characterized by that cau-
tion, sound judgment, and accuracy, for which the Stevenson
family is so distinguished. The following subjects, which em-
brace almost every description of work that comes under the
practice of the engineer, are treated of, viz., Harhours- — Lake
Navigation — River Navigation — Steam Navigation — Fuel and
Materials — Canals — Roads — Bridges — Railways — Water-
works— Lighthouses — and Housemov'mg^ an operation peculiar
to the United States.

Our author, after detailing the character of the American
harbours, next treats of Lake Navigation, which, as is well
known, is stopped for a considerable period (three months) every
year, by the ice. On the subject Mr Stevenson says, " The pe-
riod at which lake navigation closes, is generally about the end of No-
vember or beginning of December, and this interruption is never removed
before the first week of May. In 1887, the year in which I visited Ame-
rica, the navigation was not wholly open till the last week of May. On
the 20th of that month, I passed down Lake Erie, on my way to Buffalo,
in the steam-boat ^' Sandusky," on which occasion, even at that late pe-
riod in summer, we encountered a large field of floating ice, extending
as far as the eye could reach. Our vessel entered the ice about seven
o'clock in the morning, and at twelve in the forenoon she had got nearly
half-way through this obstacle, when a breeze of wind sprung up, which,
from its direction, had the effect of consolidating the field into a mass so
compact, that our vessel being no longer able to penetrate it, was detain-
ed a prisoner at the distance of about ten miles from Buffalo, the port for
which she was bound. During the two following days, the efforts of our
ere w to free the vessel were unavailing, and so tliick was the field of ice
by which we were surrounded, that several of our less patient and per-
haps more adventurous fellow passengers, made many fruitless attempts
to reach the shore, which was only two or three miles distant, by walk-
ing over its surface. On the morning of the 23d, a breeze of wind fortu-
nately loosened the ice, and our captain, after having seriously damaged
his vessel in attempting to extricate her, succeeded in making his escape,
and landed his unfortunate passengers during a torrent of rain, on tlie
shores of the lake, far from any house, and ten miles from Buffalo, the

New Publications. 207

place of our destination. The circumstance of there being upwards of
two hundred passengers on board, and a great scarcity of provisions, to-
gether with the coldness of the weather, rendered our situation during the
forty-eight hours of our imprisonment far from agreeable,

" The country through which I travelled for some days before reaching
the shores of the lakes, on my way from the Ohio River to Lake Erie,
and also that part of it through which I passed on my route from the
lakes to Quebec, presented all the indications of summer, everj^ tree and
shrub being in full foliage. In the immediate neighbourhood of Lake
Erie, however, no signs of the approach of spring or returning vegetation
were visible, though it was towards the end of May. The countr}'- sur-
rounding the margin of the lake was bleak, and the trees were leafless,
while the atmosphere was exceedingly damp, and the temperature indi-
cated by the thermometer ranged from 32° to 35° of Fahrenheit. Such
was the effect produced on the climate by this huge cake of floating ice,
that it was almost impossible, from the state of the lake atmosphere, and
the appearance of the surrounding country, to divest one's-self of the
idea that winter was not yet gone, although in fact the first month in
summer was drawing to a close. This circumstance affords a striking ex-
ample of the degree in which climate may be influenced by local circum-
stances ; for, while the shores of Lake Erie presented this sterile appear-
ance, and were still plunged in the depths of winter, the country in the
neighbourhood of Quebec, although lying three degrees further north,
was richly clothed with vegetation.

" The transition from winter to summer in the northern parts of North
America, is very sudden. There is no season in that country correspond-
ing to our spring. The vast heaps of hardened snow and ice which have
accumulated during the winter, remain on the ground long after the sun
has attained a scorching heat, but it is not until his rays have melted and
removed them, that the climate becomes really warm, and then the foliage
being no longer checked by the cold produced by these masses of snow and
ice, instantly bursts forth, and at that particular time a single day makes
a marked difference on the i^ce of the countr}%"

The river navigation of America, which is next considered,
affords an opportunity of giving a minute description of those
great rival rivers, the St Laurence and the Mississippi. The
systems of navigating those rivers are very different, the St

Laurence bemg " distorted by numerous expansions and contractions
of its banks, and also by declivities or falls in its bed, and clusters of
small islands, which render its navigation exceedingly dangerous^ and in
some places wholly imjjracticable for all sorts of vessels excepting the
Canadian hatteaux, which are strong flat-bottomed boats, built expressly
for its navigation. While the bed in which the Mississippi flows, is of a
soft alluvial formation, maintaining a nearly uniform breadth throughout

208 Nezo Publications.

its whole course, and aflPording, at everj' point below the falls of St An-
thony (which are 2250 miles from the Gulf of Mexico), a sufficient depth
of water for vessels of the largest size."

The steam navigation of America seems to have occupied a
considerable share of the author's attention, and he accordingly
devotes a long chapter to that subject, in which there is much
that has not before, so far as we know, been published.

The American canals, roads, bridges, and railways are am-
ply described ; in the subject of road-making and water-works
we meet with much interesting information; and, when treat-
ing of lighthouses, a very important department of civil en-
gineering, Mr Stevenson remarks —

'^ The fact of a lighthouse system having been extended to the remot-
est corners of so extensive a coast, under circumstances so inauspicious
and unfavourable, is what could hardly have been looked for, and is cer-
tainly highly creditable to the government of the United States and to
the officers of the Lighthouse Establishment. Even the most superficial
observer cannot fail to discover that there is a striking contrast between
the regulation of that establishment and the efficient and admirable sys-
tems pursued by the Lighthouse Boards of Great Britain and France ; but
a candid enquirer will rather be disposed to admire the activity and zeal
which have extended the benefit of lighthouses to remote and unhospi-
table regions, of difficult access, than to wonder at the defects of the sys-
tem which has been established for the purpose of carrying that import-
ant object into effect."

The volume concludes with a chapter on house-moving, but
for the details of this curious engineering operation, we must
refer to the work itself.

2. Memoirs of the Wernerian Natural History Societi/y for the years 1831-37.
Vol. VII. With thirty-fire coloured Geological Sections, and a coloured Geo-
logical Map ; and sixty-seven Illustrative Figures of Fishes. 8vo. Pp. 550.
1838. Black & Co., Edinburgh ; and Longman & Co., London.

/
Tins richly illustrated and valuable volume, contains an account of the
geology of the county of Edinburgh, also of the counties of East and
West Lothian ; and an ample natural history of the more] interesting
fishes of Scotland. It will serve as a very useful geological guide to
travellers who may visit the middle district of Scotland with the view of
studying our Neptunian and Plutonian transition and secondary rocks ;
and those ichthyologists who take an interest in the natural and econo-
mical history of British fishes, will have evcrv reason to be satisfied with
the store of useful and accurate infonnation which this volume afibrds.

New Publications. 209

3. Insecta Lapponica descripta^a Johanne Wilhelmo Zetterstedt. 1 vol. ito*

Lipsice, 1838.

When we consider the remote geographical position of the more north-
ern regions, in connection with the internal difficulties they oppose to ac-
cess from their rugged surface and inclement sky, it seems a matter of
gratulation that our information regarding their zoology is so ample as it
really is. By far the largest and most important share of it has been the
fruit of the many Polar expeditions undertaken of late years ; but much
has likewise been contributed by the naturalists of the northern parts of
the European continent. The result of their combined researches per-
haps warrants the inference, that comparatively few of the higher land
animals (birds and mammalia) of the more northern latitudes remain un-
discovered ; for while it must be admitted that many tracts have been
imperfectly explored, not to say altogether unvisited, it should be borne
in mind that the same stern influences of climate and situation by which
this has been prevented, operate with equal efficacy in restricting the
circle of animal life.

But our knowledge of northern zoology is not confined to the more
conspicuous and easily discovered tribes ; annulose animals have likewise
received a due share of attention, and the entomology of several regions
has been investigated with much care. This is the case in particular
with some of the countries in the north of the continent of Europe, where
the study of insects has of late been making rapid progress. It is impos-
sible, indeed, to look into the Transactions of northern societies, such as
those of Moscow, Petersburgh, Stockholm, &c., without being struck
with the large proportion of their pages usually devoted to this subject.
Nor is it at all surprising that it should be so. The higher animals indi-
genous to a northern climate are necessarily few ; their habits and attri-
butes, as far as they fall under the province of the naturalist, are soon
ascertained ; and he is therefore obliged, in order to gratify his taste for
investigating the characters and relations of specific forms, as well as ob-
serving the habits and instincts of living beings, to enter the only field
that afibrds scope for exertion. While that of entomology is sufficiently
extensive for such a purpose, it is, in one point of view, no inconsiderable
inducement to the study, that in a northern locality it is not too ample.
The teeming exuberance, and almost endlessly diversified forms of living
creatures, in such a region as Brazil, for example, must, we cannot help
thinking, produce a discouraging efiect on a naturalist attempting to ex-
plore it, when he reflects how small a portion of the collective mass he
can hope to become sufficiently acquainted with, or make known to others
at a distance ; and that even if the greater part of his life were devoted to
the pursuit, he would scarcely make a nearer approach to producinga com-
plete fauna of the country, than would the labours of a few husbandmen
to convert its pathless and far-stretching forests into level and fertile
VOL. XXVI. NO. LI.-T-JANUAllY 1838. O

^10 New PubUcations,

fields. But in such countries as Norway and Sweden, L^land or Scot-
land, the objects, although still numerous, are by no means oppressively
or unmanageably so ; and it is no small encouragement to attempt their
investigation, to have the prospect of being able to frame, vrith a mode-
rate degree of labour, a complete fauna of a district, which can be ap-
pealed to as a faithful index to all the living creatures scattered over its
surface.

Of all the northern countries of Europe, Sweden has been most favour-
ed in the number and eminence of her entomologists. Not fewer than
five or six Insectorum Faunee Suecicce have appeared, besides numerous
insulated treatises and papers referring to the same subject. Among the
names of her inhabitants, famous in this department of zoology, are found
those of Linnseus, De Geer, Gylienhal, Paykull, Thunberg, Fallen, and
many others of scarcely inferior note.

The naturalist whose name has been mentioned at the commencement
of this notice, has selected a still more northern region as the scene of his
entomological labours. He has undertaken to make us acquainted with
the insects inhabiting the most northern country t»i Europe, — a region
but seldom visited by those capable of adequately describing its produc-
tions. The manner in which he has executed his task is deserving of high
approbation. He has visited the most remote and inhospitable parts of the
country, and availed himself of every opportunity of increasing his know-
ledge of its insect population. His exertions have been rewarded by the
discovery of multitudes of new species in almost every order ; among the
diptera alone he has added 572 species to the number already known !
In treating of the coleoptera and orthoptera, he has judiciously abstain-
ed from giving lengthened descriptions, as they have already been so
often described in works accessible to all ; but the other tribes are treat-
ed with great minuteness of detail, in order to supply, so far, the want
of proper descriptive works relating to them. The hymenopterous and
dipterous portions of the work must be looked upon as a very valuable
contribution to natural history. Considerable light is also thrown on the
geographical distribution of insects in the extreme north of Europe, as
well as their more local distribution relatively to the altitude, tempera-
ture and topical character of the country. In order to shew the ascer-
tained extent of insect life in these high latitudes, we shall state the num-
bers of the different orders contained in M. Zetterstedt's work ; and for
the purpose of comparison annex the amount of the same orders as they
occur in Britain.

Lapland.

Britain.

Coleoptera,

964

3298

Orthoptera,

27 .

58

Hemiptera,

233

605

Hymenoptera,

456

2054

Diptera,

1251
2931

1662
7677

New Publications. ^H

The author divides Lapland into four regions, each of which is charac-
terized by a particular climate, soil, or vegetation, and therefore also by
particular species of insects. These regions are the wooded, the *«&-
wooded or sub-alpine, the alpine, and the infra-alpine regions. The for-
mer of these, from the beginning of June to the end of September, is en-
tirely free from snow in the valleys, and, enjoying a very considerable
temperature, produces many of the common species of Sweden in some
plenty. Elaphrus, Harpalus, Aleocliara, Dytiscus, Hyphydrus, Elater,
Cimbex, Tenthredo, numerous Jchneumonidce, Bombus, and multitudes of
Diptera (especially Tipulidce), are a few of the genera that we can afford
room to name. The sub-alpine region, although lying near the verge of
the linm citing snows, is by no means destitute of vegetation in the months
of July and August, and maintains among its willows, dwarf birches, and
alpine plants, many of the insects found in the lower region, as well as
several others peculiar to itself. Among the latter, we may mention
Harpalus alpinus, Anthophagus alpinus, Omalium alpinum, Boreaphilus
Henningianus, Cantharis Lapponica, Chrysomela Lapponica, Eurytoma
minuta, Lyda flavipes, Bassus alpinus, Tabanus alpinus, Gonia fiaviceps,
Tachina pubicornis, Musca dolens. Simulice, and Culices, abound in the
birch groves of this region, and prove no small annoyance to travellers.
The alpine region comprehends the highest mountain ranges in the
country, which of course are covered with perennial snows. " Frigido
gremio," to use the author's expression, '' minorem numerum insectorum
fovet." Yet the greater proportion of such as do inhabit these bleak and
dreary solitudes, are peculiar to them, seldom or never descending to the
milder regions below. Such are Harpalus Quenseli, var. alpinus, rufipes,
Hyphydrus nigrita, Rhynchcenus arciicus, Curculio Icevigatus, Tenthredo
opaca, Vespa borealis, (n. s.)* Anthophora inermis, Cryptus pullulator,
(n. s.) Bassus pubescens, (n. s.) Bombus alpinus, var. B. nivalis, &c. and
about twenty species of Diptera, including, however, very few Tipulidse,
yet the occurrence of a few of the latter ought to have led the author to
modify the assertion in the commencement of his work, " Tipularisa
gummas alpes omnino aufugiunt." We are somewhat surprised at the
author assigning Carabus glabratus and Notiophilus aquaticus to his alpine
region. The former is certainly an alpine insect in Scotland, but it fre-
quently descends the sides of the mountains, and may even be met with
occasionally in the valleys, circumstances which would have inclined us
to suppose that it would have found its appropriate abode in Lapland, in
the sub-alpine zones. The same observations apply still more forcibly to

* This species, which very closely resembles the common wasp, sometimes
descends to the plains. Tlie common wasp, in certain localities, is partial to
elevated situations ; it is found at a higher elevation on the Peak of Tene-
riflfe, than any other insect.

212 New Publications.

tho Notiophilus, which is common throughout the lowlands of Scotland ;
the other species, iV. biguttatus, more affects elevated districts, which
renders it singular that it does not occur in Lapland. Yet JV. aquaticus
is one of the species M. Zetterstcdt found at the highest elevations, botli
on alpine ranges, and insulated mountains, creeping on the surface of
the snow in the month of July. The other kinds mentioned as occurring
at the greatest altitudes, are Bembidiam bipunctatunij JVebria GyllenhalU
Harpalus melanocephalus, Quenseli, picicornis, (n.s.) Anthophagus alpinus,
omcUinus; Omalium impressum ; Curculio Maurus ; Chrysomela affinis,
alpina, (n. s.) Blatta Lapponica.

What the author calls the infra-alpine region is in Western Lapland,
or Nordland and Finmark, and lies between the alpine ridge and the
northern and icy sea. The islands and shores of this district, and the
little valleys, often of great beauty, which open between the hills, and
concentrate the rays of the sun, produce many insects not found in other
situations within these latitudes. Of these we can mention only a few,
Cicindela maritima, Harpalus Icevipes, (n. s.) Hydrophilus spinosus, Hy-
phydrus rivaliSj Curculio Bohemanni, alpinus, Schbnherri (all new spe-
cies), Haltica borealis (n. s.), Acridium bimaculatum, Cicada confinis,
lunulata, grisescens, alpina (likewise all new), Vespa Normgica, Bomhus
Lapponicus, var. and hyperboricus, Tabanus auripilus, Chrysops nigripes,
(Estrus trompe, Phasia opaca.

4. Traits 4lementaire de Conchyliologie, avec Vapplication de cette science
d, la Giognosie. Par. G. P. Deshayes {chcz Crochard et Cie Paris.)

We have just received the first Livraison of this new work by one of
the first conchologists of the day. The whole treatise will extend to two
volumes 8vo, and will be illustrated by 100 plates ; it will be published
in twelve parts, one of which will appear every two months, commenc-
ing from the first November last. The author begins with an historical
introduction ; which is to be followed by an essay on the comparative
anatomy of the Mollusca, and by an account of the families and genera.
When making his critical observations, and giving the characters of each
genus, it is the intention of M. Deshayes to select as examples the spe-
cies that are characteristic of the various formations. At the end of each
genus the number of living and fossil species will be given, together with
an account of the distribution of the latter in the different strata compos-
ing the earth's crust. The fossil species which have their living analogues
will be specially mentioned, and also the fossils occurring in different
beds as to superposition, or in similar beds that are situated at great dis-
tances from each other. We have no hesitation in earnestly recommend-
ing this most useful pubhcation to the attention of all conchologists and
geologists.

New Publications. 218

6. A Dictionary of Arts, Manufactures, and Mines. By Andrew Ure,
M.D., F.R.S. &c. Parts II. III. and IV. Longman & Company.

In these we find the following valuable articles, independently of many
others also interesting to the artizan, manufacturer, and general reader —
viz. Bleaching — Block-Making — Bread — Brick — Button — Calico-Print-'
ing — Cotton Manufactures — Distillation — Dj'eing — Embroidery — Filtra-
tion—Fire-Arms—Flax. .•V.V,b>VVV,W^,HTv.V,

0. Journal of the Asiatic Society of Bengal, Edited by Mr Princep.
No. 76. March. 8vo. 1838. Calcutta : and Messrs W. H. Allen &
Company, London.

It is our intention in future to announce quarterly the appearance of this
very valuable Journal as it reaches us from India. In the present number
are the following, besides other, interesting articles. 1. On the Revolutions
of the Seasons ; by Rev. Robert Everest. 2. Table of Indian Coal ana-
lyzed at the Calcutta Assay Office, &c. arranged from the Report of the
Coal Committee. 3. On a remarkable Heat observed in masses of Brine
kept for some time in large reservoirs ; by G. A. Princep, Esq. 4. On the
Land and Fresh Water Shells of the Western Himalaya ; by Lieut. T.
Hutton, 27th Regiment, N.I., and W. H. Benson, Esq. C.S. 5. Me-
teorological Register.

7. Observations on the Genus Unto. By Isaac Lee, Member of the Ame-
rican Philosophical Society, &c. &c. &c. 4to. With numerous colour-
ed plates.

This elegant and accurate volume will, we doubt not, find a place in
every conchological library. It is the result of the long-continued in-
vestigation of one of the most active and judicious American naturalists,
and one too, who enjoys a European celebrity.

8. Report of the Geological Survey of Connecticut. By Charles Shepard,
M.D., pp. 188. Newhaven, United States. 1837.

Dr Shepard, who joins to an accurate acquaintance with simple mine-
rals, much geological knowledge, was employed by the American Go-
vernment to survey geologically the State of Connecticut. The results of
his labours are contained in this interesting volume, which we find, on
careful perusal, to afford much information, equally valuable to the geo-
logist and mineralogist.

( 214 )

List of Patents granted in Scotland from 15th September to
Uth December 1838.

1. To Samuei. Hall of Basford, in the county of Nottingham, civil en-
gineer, for an invention of " improvements in steam-engines, heating or
evaporating fluids or gases, and generating steam or vapours." — 15th Sept.
1838.

2. To William Joseph Curtis of Stamford Street, Blackfriars Road,
in the county of Surrey, civil engineer, for an invention of " certain im-
proved machinery and apparatus for fiicilitating travelling and transport on
railways, parts of which are also applicable to other pui-poses." — 17th Sept.
1838.

3. To Thomas EoBiNsoif Williams of No. 61 Cheapside, in the city of
London, civil engineer, for an invention of " certain improvements in ma-
chinery for spinning, twisting, or curling and weaving horse-hair, and other
hairs, as well as various fibrous substances." — 18th Sept. 1838.

4. To Archibald M'Lelland of the city of Glasgow, coach-builder, for
an invention of " certain improvements upon the springs and braces of
wheel carriages, and upon the mode of hanging such carriages." — 21st Sept.
1838.

6. To Robert William Sievier of Henrietta Street, Cavendish Square,
in the county of Middlesex, gentleman, for an invention of " certain im-
provements in looms for weaving, and in the mode or method, of producing
figured goods or fabrics." — 1 st Oct. 1838.

6. To JoHs- RoBB, residing at No. 13 Commercial Road, Hutchesontown,
Glasgow, mechanic, for an invention of " a machine for preparing wood for
joiners, carpenters, and others." — 2d Oct. 1838.

7. To Edmond Henze of Fenton's Hotel, James' Street, in the county
of Middlesex, merchant, in consequence of a communication made to him
by a certain foreigner residing abroad, for an invention of " improvements
in the manufacture of dextrine." — 8th Oct. 1838.

8. To Robert William Sievier of Henrietta Street, Cavendish Square,
in the county of Middlesex, gentleman, for an invention of " certain im-
provements in rigger and pulley bands for driving machinery, and ropes
and lines for other purposes." — 11th Oct. 1838.

9. To James Nasmyth of Patricroft, near Manchester, in the county of
Lancaster, engineer, for an invention of " certain improvements in Ma-
chinery, Tools or Apparatus for cutting or planing metals and other sub-
stances, and in securing or fastening the Keys or Cottars used in such ma-
chinery, and other machinery where Keys or Cottars are commonly applied."
—11th Oct. 1838.

10. To Thomas Ridgway Bbidsok of Great Bolton, in the county of
Lancaster, bleacher, for an invention of " certain improvements in the con-
struction and arrangements of Machinery or Apparatus for stretching,
mangling, drying, and finishing woven goods or fabrics, and part or parts of
which improvements are applicable to other useful purposes." — 12thOct.l838.

11. To William Angus Robertson of Peterborough Court, Fleet
Street, in the city of London, patent agent, for an invention of " certain
improvements in the Manufacture of hosiery, shawls, carpets, rugs, blan-
kets, and other fabrics," being a communication from a certain foreigner
residing abroad.— 12th Oct. 1838.

12. To John Seaward, of the Canal Iron Works, Poplar, in the county
of Middlesex, for an invention of " an Improvement in Condensing Steam-
Engines."— 12th Oct. 1838.

13. To John Wordsworth of Leeds, in the county of York, machine-
maker, for an invention of " Improvements in Machinery for heckling and
dressing flax, hemp, and other fibrous materials." — I8th Oct. 1838.

List of Patents. 215

14. To John Melling of Liverpool, in tlic county of Lancaster, for an
invention of " certain Improvements in Locomotive Steam-Carriages to be
used on railways or other roads, part or parts of which improvements are
also applicable to Stationary Steam-Engines, and to Machinery in general."
—18th Oct. 1838.

15. To Horace Cohy of Marrow Street, Limehouse, in the county of
Middlesex, bachelor of medicine, for an invention of " Improvements in the
manufacture of White Lead."— 18th Oct. 1838.

16. To Heney Huntley Mohun of Regent's Park, in the county of
Middlesex, M. D., for an invention of " Improvements in the composition
and manufacture of Fuel, and in furnaces for the consumption of such, and
other kinds of Fuel."— 18th Oct. 1838.

17. To Edwin Bottomley of Aldermanbury, in the county of York,
clothier, for an invention of " a certain improvement or improvements ap-
plicable to power and hand looms." — 29th Oct. 1838.

18. To Laitrence Hey worth of Yew Tree, near Liverpool, in the
county of Lancaster, merchant, for an invention of "a new method of ap-
plying steam power directly to the periphery of the movement vheed, for
purposes of locomotion, both oji land and water, .and for propelling ma-
chinery."—29th Oct. 1838.

19. To Thomas Evans of the Dowlar's ironworks, in the county of Gla-
morgan, agent, for an invention of " an improved rail for railway purposes,
together with the mode of manufacturing and fastening down the same." —
3ist Oct. 1838.

20. To Pierre Arma-nd Lecomte tje "FtMrrAiWEOTonEHAti of Oharles
Street, City Road, in the county of Middlesex, for an invention of " certain
improvements in wool combing," being a communication from a foreigner
residing abroad. — 2d November 1838.

21. To Ja3ies Milne of Edinburgh, North Britain, brassfounder, for an
invention of " an improvement or improvements in apparatus, employed in
traaismitting gas for the purpose of light and heat," — 6th Nov. 1838.

22. To John Henfrey of Weymouth Terrace, in the parish of Shore-
ditch and county of Middlesex, engineer and machinist, for an invention of
" certain improvements in the manufacture of hinges or joints, and in the
machinery employed therein." — 6th Nov. 1838.

23. To Charles Flude of Liverpool, chemist, for an invention of "im-
provements in applying heat for smelting, or otherwise working ores, me-
tals, and earths, and for heating steam-boilers, and for general manufacturing
or other useful purposes where heat is required, and also for an improved
inode of supplying hot water to steam-boilers, the said improvements having
the economy of fuel for their object." — 6th Nov. 1838.

24. Okristopher Nickels of York Road, Lambeth, in the county of
Surrey, manufacturer, for an invention of " improvements in machinery for
covering fibres, applicable in the manufacture of braid and other fabrics."
7th Nov. 1838.

25. To Thomas French Berney of Mortonhall, in the ooxmty of Nor-
folk, Esq. for an invention of " certain improvements in cartridges.^'— 8th
Nov. 1838.

27. To Michael Wheelwright Ivison, eilk-spinner, residing in No. 19
Giliiiore Place, Edinburgh, for an invention of " an improved method for
preparing and spinning silk-waste, wool, flax, and other fibrous substances,
and for discharging the gum from silks, raw and manufactured." — 9th Nov.
1838.

28. To Moses Poole of Lincoln's Inn, gentleman, in consequence of a
comnmnication from abroad, for an invention of " improvements in appara-
tus or machineiy for obtaining rotatoiy motion." — 14th Nov. 1838.

29. To Thomas Mellodeav of Wallshaw Cottage, in the township of Old-
ham, in the county of Lancaster, mechanic, for an invention of " certain
improvements in looms for weaving various kinds of cloth." — 14th Nov. 1838.

30. To Christopher Binks of Newington, in the coimty of Edinburgh,
manufacturing chemist, for an invention of " certain improvements in the

«16 List of Patents,

process or processes for obtaining or manufacturing certain substances or
compounds applicable in bleaching, and for rendering useful certain pro-
ducts which result therefrom, also improvements in the apparatus employed
therein, and in bleaching, and for the application thereto of a certain agent
not hitherto so employed ; which improvements are also in whole or in part
applicable to other uses." — 15th Nov. 1838.

31. To RoBEiiT Beart, of Huntingdon, miller, for an invention of "im-
provements in apparatus for filtering liquids." — 27th Nov. 1838.

32. To AuGTisTE Victor Joseph Baron D'Asda, of Millman Street,
Bedford Row, in the county of Middlesex, in consequence of a communica-
tion made to him by a certain foreigner residing abroad, for an invention of
** improvements in producing or affording light, which he intends to deno-
minate a solar light."— 29th Nov. 1838.

33. To John Barnett Humphreys, civil engineer, for an invention of
" improvements in marine and other steam-engines." — 29th Nov. 1838.

34. To Richard Lamb, of David Row, Southwark, gentleman, for an in-
vention of " improvements in apparatus for supplying atmospheric air in the
production of light and heat."— 29th Nov. 1838.

35. To James Timmins Chance, of Birmingham, in the county of War-
wick, glass manufacturer, for an invention of " improvements in the manu-
facture of glass."— 29th Nov. 1838.

36. To Paul Chappe of Manchester, in the county of Lancaster, spinner
and manufacturer, for an invention of " certain improvements in the means
of consuming smoke, and thereby economizing fuel and heat in steam-en-
gine or other furnaces or fire-places ; which improvements are also appli-
cable in preventing the explosion of boilers." — 30th November 1838,

37. To Samuel Seaward of the Canal Iron- Works, Poplar, in the
county of Middlesex, engineer, for an invention of " certain improvements
in marine steam-engines." — 30th November 1838.

38. To Henry Davies of Stoke-Prior, in the county of Worcester, en-
gineer, for an invention of " certain improved apparatus or machinery for
obtaining mechanical power, also for raising or impelling fluids, and for as-
certaining the measure of fluids." — 7th December 1838.

39. To Joseph Bolton Doe of Hope Street, Whitechapel, in the county
of Middlesex, iron-founder, for an invention of " certain improvements in
apparatus used in the manufacture of soap." — 7th December 1 838.

40. To Fanquet Delarne junior, late of Daville, near Rouen, in the
kingdom of France, but now residing at the London CoiFee-house, in the
city of London, gentleman, for an invention of " certain improvements in
printing and fixing fast, red, black, and other colours, upon cotton, silk,
woollen, and other fabrics, without the usual process of dyeing." — 11th
December 1838.

41. To Theodore Cotelle of the Haymarket, in the county of Middle-
sex, civil-engineer, for an invention of " improvements in extracting the
salt from sea or salt water, and rendering it pure or drinkable, and in puri-
fying other water." — 14th December 1838.

42. To William Crofts of Radford, in the county of Nottingham,
machine-maker, for an invention of " improvements in the manufacture of
lace."— 1 4th December 1838.

43. To Henry Adcock of Mount Place, Liverpool, in the county of Lan-
caster, civil-engineer, for an invention of " certain improvements in the
raising of water from mines and other deep places." — 14th December 1838.

44. To William Thorp and Thomas Meakin of Manchester, in the
county of Lancaster, silk-manufacturers, for an invention of " certain im-
provements in looms for weaving, and also a new description of fabric to
be produced or woven therein. — 14th December 1838.

THE

EDINBURGH NEW
PHILOSOPHICAL JOURNAL.

Historical Eloge of Joseph Fourier. By M. Aeago, Perpe-
tual Secretary to the Academy of Sciences of France.
(Concluded from page 25.)

The official labours of the prefect of Isere scarcely inter-
fered with the occupations of the literary man and the geome-
trician. It was from Grenoble that the principal writings of
Fourier were dated ; and it was at Grenoble that he framed
the mathematical theory of heat, which forms his principal claim
to the gratitude of the learned world.

I am fully aware of the difficulty of giving a clear analysis
of this admirable work ; but, nevertheless, I shall try to point
out, one by one, the progressive steps by which it has ad-
vanced science. You will, I hope, gentlemen, listen patiently
to some minute technical details, whilst I fulfil the commission
with which you have honoured me.

The ancients had a taste or rather a passion for the marvel-
lous, which made them forget the sacred duties of gratitude.
Look at ihem, for instance, collecting into one single group
the high deeds of a great number of heroes, whose names they
have not even deigned to preserve, and attributing them all to
Hercules alone. The lapse of centuries has not made us wiser.
The public, in our times, also delight in mingling fiction with
history. In all careers, particularly in that of the sciences,
there is a desire to create Herculeses. According to the vul-
gar opinion, every astronomical discovery is attributable to
Herschel. The theory of the motions of the planets is iden-
tified with the name of Laplace ; and scarcely any credit is
allowed to the important labours of D'Alembert, Clairaut,
Euler, and liagrange. Watt is the sole inventor of the steam-
engine ; whilst Chaptal has enriched the chemical arts with

VOL. XXVI. NO. LII.—APRIL 1839. '

^18 M. Arago's Historical Eloge of Joseph Fourier,

all those ingenious and productive processes which secure their
prosperity. Did not an eloquent person affirm lately, within
these very walls, that the subject of heat was scarcely studied
before Fourier ; that this celebrated geometrician had himself
made more observations than all his predecessors put together ;
and that, after inventing a new science, he had almost perfected
it at once.

At the risk of being much less interesting, the organ of the
Academy of Sciences must refrain from such bursts of enthu-
siasm. He ought to recollect that these eloges are not only in-
tended to celebrate the discoveries of academicians, but that
they are also designed to encourage humble merit ; and that a
philosopher who is neglected by his contemporaries, is often
cheered amid his toilsome labours by the thought that he will
obtain justice from posterity. In so far as that depends on us,
let us take care that a hope so natural and so just be not de-
ceived. Let us hold up to legitimate admiration those chosen
men whom nature has endowed with the valuable faculty of
grouping together innumerable isolated facts, and deducing
beautiful theories from them ; but do not let us forget that the
sickle of the reaper had cut down the stalks of corn before any
one could think of collecting them into sheaves.

Under the subject of heat are included the natural pheno-
mena and those produced by art, two perfectly distinct forms,
which were separately investigated by Fourier. I shall adopt
the same division, commencing, however, the historical analysis,
which I am to lay before you, with radiant heat.

Nobody can doubt that there is a physical diiFerence, well
.wortiay of being studied, between a ball of iron at the ordi-
nary temperature, which can be handled with impunity, and
a ball of iron of the same dimensions which has been strongly
heated in the furnace, and which one cannot approach without
the risk of being burned. This diiFerence, according to most
natural philosophers, arises from a certain quantity of an elastic
fluid which is imponderable, or at least which is regarded as
such, with which the second ball had entered into combination
during the process of heating. The fluid which, by combin-
ing with cold bodies, renders them hot, is known by the name
of heat or caloric.

M. Arago's Historical Eloge of Joseph Fourier, 219

Substances differently heated, act on each other, even at great
distances, and through a vacuum, for the colder become heated,
and the warmer become cool : thus, after a certain interval,
they all arrive at the same degree, whatever the original dif-
ference of their temperature may have been.

In the hypothesis which we have mentioned, there is only
one mode of explaining this distant action. It consists in sup-
posing that it is effected by means of certain effluvia which
pass through space from the hot body to the cold body ; and it
is asserted that a warm body throws out rays of heat all around
itself, as luminous bodies throw out rays of light.

The effluvia, or radiant emanations, by means of which two
bodies at a distance from each other keep up a calorific com-
mimication, have been very properly denoted by the term ra-
di&nt caloric.

Radiant caloric had been previously, whatever may have
been said to the contrary, the subject of important experiments.
before the investigations of Fourier. The celebrated academi-
cians del Cimento, found, nearly two centuries ago, that this
caloric is reflected like light ; and that, like light, it is concen-
trated in the focus of a concave mirror.* By substituting balls
of snow for heated bodies, they even proved that frigorific foci
may be formed by reflexion.

Some years afterwards, Mariotte, a member of this academy,,
discovered that there are certain kinds of radiant caloric ; and
that that which accompanies the solar rays, traverses all tran-
sparent media as easily as light ; whilst the caloric which ema-
nates from a strongly heated substance before it becomes red
hot, as well as the calorific rays which are mixed with the lu-
minous rays from a body at a moderate degree of incandescence,
are almost completely absorbed in passing through a plate of
the most transparent glass !

This curious discovery, I may remark, shews, notwithstand-
ing the sneers of pretended philosophers, how correct in th^ir
ideas the workmen in foundries were, who, from time imme-
morial, only looked at the incandescent matter in their fur-

* This was observed, as well as the apparent reflection of cold, long be-
fore, by Baptista Porta. Mag. Nat. p. 6«9. Edit. 1597. F.

p2

220 M. Arago's Historical Eloge of Joseph Fourier.

naces through a piece of common glass, expecting, by means of
this contrivance, to intercept the heat which would have burned
their eyes.

In all the experimental sciences, the periods of brilliant pro-
gress are almost always separated from each other by long in-
tervals of nearly perfect repose. Thus, after Mariotte, more
than a century passes without history having to record any new
property of radiant heat. Afterwards, and step by step, there
are found in the solar light, non-luminous calorific rays, whose
existence could not have been proved unless by the thermome-
ter, and which can be completely separated from the luminous
rays by means of the prism ; it is discovered, in reference to
terrestrial bodies, that the emission of calorific rays, and, conse-
quently, the cooling of these bodies, is considerably lessened by
polishing their surfaces ; and that the colour, the nature, and the
thickness of the covering with which their surfaces may be
invested, also exercise a manifest influence on their emissive
power : finally, experiment, correcting the vague conjectures
to which the most enlighted minds so foolishly abandon them-
selves, shews, that the caloriHc rays proceeding from the sur-
face of a heated body, have not the same force or the same in-
tensity in all directions ; that the maximum corresponds to the
perpendicular emission, and the minimum to the emissions
parallel to the surface.

Between these two extreme positions, how is the diminu-
tion of the emitting power effected ? Leslie was the first to
attempt the solution of this important question. His observa-
tions seemed to prove that the intensities of the emitted rays
are proportional — I must, gentlemen, make use of the scientific
expression — to the sines of the angles which these rays form
with the heated surface ; but the quantities on which it was ne-
cessary to operate were too small, and the uncertainty of the
thermometric determinations, compared to the whole effect,
was, on the contrary, too great, not to cause extreme distrust.
Well, gentlemen, a problem which had defied all the processes
and all the instruments of. modern physics, was completely
solved by Fourier, without attempting any new experiment. The
required law for the emission of caloric was, with a sagacity
which cannot be sufficiently admired, discovered in the most

M. Arago's Historical Eloge of Joseph Fourier. 221

common phenomena of temperature, in phenomena which, at
first sight, seem to be perfectly unconnected with it.

Such is the privilege of genius ; it perceives, it seizes on re-
lations where ordinary eyes only see isolated facts.

Nobody doubts, and, besides, experience has shewn, that, in
all the points of any space contained within certain boundaries,
and su])ported at a constant temperature, we cannot find a tem-
perature both constant and precisely the same as that of the
envelope. Now Fourier has established, that, if the emitted
calorific rays had an equal intensity in all directions, that if this
same intensity did not vary proportionally to the sine of the
angle of emission, the temperature of a body in the interior
would depend on the situation which it occupied in it : that
the temperature of boiling water or of melted iron, for in-
stance, would exist at cei'taln points of a hollow envelope of ice!!
Within the vast range of the physical sciences, we could not
find a more striking application of the celebrated method of
reductio ad absurdum, which the old mathematicians employed
to demonstrate the abstract truths of geometry.

I shall not pass from this first portion of the works of Fou-
rier, without adding, that he did not rest satisfied with point-
ing out so happily the remarkable law which connects the
comparative intensities of the calorific rays thrown out at all
angles from heated bodies ; but he also examined into the
physical cause of this law, and discovered it in a circumstance
which his predecessors had entirely overlooked. Let us sup-
pose, said he, that bodies emit heat not only from their super-
ficial particles, but also from those in the interior. Let us ad-
mit, moreover, that the heat of these latter cannot arrive at the
surface, by passing through a certain quantity of matter, with-
out experiencing some absorption. Fourier reduced to calcu-
lation these two hypotheses, and deduced mathematically from
them the experimental law of the sine. After standing so
complete a test, the two hypotheses were completely confirmed ;
they became laws of nature, and represented, in caloric, hidden
properties which could only be mentally appreciated.

In the second question treated of by Fourier, heat is pre-
sented under a new form. There is more difficulty in follow-

M. Arago*s Historical Eloge of Joseph Fourier.

ing his mode of procedure, but the deductions from the theory
are more general and more important.

Heat, when concentrated on any point of a solid body, is
communicated, by means of conductibility, to the particles
nearest the heated point, and afterwards, gradually, to all parts
of the body. Hence the problem of which the following is the
enunciation :

" By what methods, and with what velocity, is the propagation
of heat effected, in bodies of different forms and natures, when
submitted to certain initial conditions ?''

The Academy of Sciences had, in fact, already proposed this
problem as a subject of a prize in the year 1 736. As the terms
of heat and caloric were not employed at that time, it was en-
titled " V etude de la nature et de la propagation dujeti /" The
word feu thus used in the programme, without any explana-
tion, gave rise to a most strange mistake. The greater num-
ber of natural philosophers imagined that it was proposed to
explain how fire {fincendie) is communicated and increased in
a mass of combustible materials. Fifteen competitors appeared,
of whom three were successful.

This competition afforded few results. Nevertheless a sin-
gular combination of circumstances and of names of individuals
will cause it to be long remembered.

The public had certainly some reason to be surprised on read-
ing the following declaration of the academy : " The question
affords scarcely any scope for geometry" ! In regard to inven-
tions, the attempt to anticipate futurity, is likely to produce glar-
ing mistakes. One of these competitors, however, the great
Euler, took these words in a literal sense. The reveries with
which his memoir abounds, are not redeemed, on this occasion,
by any of those brilliant analytical discoveries, — I had almost
said those sublime inspirations which were so common to him.
Fortunately, Euler added to his memoir, a supplement truly
worthy of him. Father Lozeran de Fiesc and Count de CrSqm^
had the high honour of seeing their names mentioned along
with that of the illustrious geometrician, although it is impos-
sible now to discover in their memoirs any kind of merit,
even that of politeness ; for the courtier has the rudeness to say

M. Arago's Historical Eloge of Joseph Fourier, 223

to the Academy, " The question which you have proposed only
interests the curiosity of mankind."

Among the competitors who were less favourably treated, we
find one of the greatest writers whom France has produced, the
author of the Henriade. Voltaire's memoir was, undoubtedly,
far from solving the proposed problem, but it was at least re-
markable for the elegance, the clearness, and the precision of
its language ; I may add also, for the close reasoning it dis-
plays ; for, if the author occasionally arrives at doubtful results,
it is only when he borrows faJse data from the chemistry and
natural philosophy of the time, — sciences which were then in
their infancy. Besides, the anii-cartesian nature of some articles
in Voltaire's memoir, was likely to find little favour in an assem-
bly where Cartesianism, with its incomprehensible vortices^ was
in full vogue.

It would be more difficult to discover the causes which led
to the rejection of the memoir by the Marchioness du Chdtelet^
for she had also entered the lists of the Academy. Her work
was not only an elegant account of all the properties of heat at
that time known to natural philosophers ; but it was also re-
markable for various proposals for experiments, one, among
others, which was afterwards followed up by Herschel, and
from which he derived one of the chief gems in his brilliant
scientific crown.

Whilst these great names were engaged in this competition,
natural philosophers who were less ambitious, laid, experimen-
tally, the solid foundations of a future mathematical theory of
heat. Some proved that the same quantities of caloric do not
raise, by an equal number of degrees, the temperature of equal
weights of different substances, and thus added to science
the important idea of capacity. Others, by means of observa-
tions not less certain, proved, that heat applied at one point of
a bar, is transmitted to the distant parts with more or less
quickness or intensity, according to the nature of the substance
of which the bar is composed : thus they gave rise to the first
ideas of conductibility. The same period, if I could enter into
. detail, would exhibit to us interesting experiments, on a law of
cooling, hypothetically admitted by Newton. We should see
that it is not true, that, at all point? of the thermometer, the

224 M. Arago's Historical Eloge of Joseph Fourier,

loss of heat in a body, is proportional to the excess of its tem-
perature above that of the medium in which it is immersed ;
but I hasten to shew you the geometrician penetrating, timidly
at first, into the questions of the propagation of heat, and in-
troducing the first germs of his prolific modes of investigation.

It is to Lambert of Miihlhausen that we are indebted for this
first step. This ingenious geometrician had undertaken the
solution of a very simple problem, of which every body can
understand the meaning.

A slender metallic bar is exposed, at one of its extremities, to
a steady and continued heat. The parts next the source of heat
are the first to become heated. By degrees the heat is commu-
nicated to the distant portions, and in a short time, each point
is found to have acquired the maximum of temperature which
it can ever attain. Although the experiment should be con-
tinued for a hundred years, the thermometrical state of the bar
would not be altered.

As might be expected, this maximum of heat is much less,
the farther it is removed from the source. Is there any con-
nexion between the final temperatures and the distances of dif-
ferent parts from the extremity directly heated ? This con-
nexion exists ; it is very simple ; Lambert reduced it to calcu-
lation, and experiment confirmed the theoretical results.

Along with the comparatively elementary question of the lon-
gitudinal propagation of heat, treated of by Lambert, there had
arisen the more general, but much more difficult problem of
this same propagation, in a body of three dimensions, termi-
nated by any sort of surface. This problem required the ap-
plication of the highest kind of analysis. Fourier was the first
to put it into a mathematical form. It is to Fourier also that
we are indebted for certain theorems by means of which we
may ascend from differential to integral equations, and carry
out the solutions, in the greater number of cases, to the ultimate
numerical apphcations.

The first memoir of Fourier on the theory of heat, is dated
so far back as 1807. The Academy, to which it had been sub-
mitted, wishing to induce the author to extend and complete
it, made the question of the propagation of heat the subject of
^he great mathematical prize which it was to give in 1812.

M. Arago's Historical Eloge cf Joseph Fourier. 225

Fourier competed, and his essay was successful. But, alas !
as Fontenelle said, " even in the region of demonstration
there is room for a division of opinion." Some restrictions
were mingled with the favourable judgment of the Academy.
The committee for awarding the prize, Laplace, Lagrange,
and Legendre, whilst they admitted the novelty and import-
ance of the subject, and declared that the true differential
equations of the propagation of heat were at last discovered,
Said that they perceived difficulties in the method by which the
author arrived at his conclusion. They added that there was
something awanting in his methods of integration, even on the
score of accuracy, although they did not support their opinion
by any kind of illustration.

Fourier never yielded to this judgment. At the close of his
life, he even shewed in a very marked manner that he thought
it unjust, as he printed his prize-essay in our volumes without
changing a single word of it. Nevertheless, the doubts ex-
pressed by the committee of the Academy continually recurred
to his memory. Even at first, they had embittered the pleasure
of his triumph. These first impressions joined to great suscep-
tibility, explain why Fourier, in the end, looked with a certain
degree of displeasure on the efforts of the geometricians who
attempted to perfect his theory. This, gentlemen, is a very
strange aberration in so elevated a mind. Our colleague must
have forgotten that it does not fall to the lot of any one indi-
vidual to perfect any scientific question, and that the great
works on the system of the world, by the d'Alemberts, the
Clairauts, the Eulers, the Lagranges, and the Laplaces, whilst
they immortalized their authors, have continued to add fresh
lustre to the imperishable glory of Newton.

Let not this example be lost on us. Since the law of the land
imposes on the tribunals the necessity of giving the reasons for
their decisions, academies, which are the tribunals of science,
can have no possible pretext for dispensing with this regula-
tion. At all periods, public bodies, as well as individuals, act
wisely, when they trust in all matters to the authority of reason
alone.

The mathematical theory of heat would, at all times, have

226 M. Arago*s Historical Eloge of Joseph Fourier,

excited a lively interest among educated men, as, supposing it
to be perfect, it would throw light on the most minute processes
of the arts. In our times, its numerous points of connexion
with the curious discoveries of geologists, have made it a pecu-
liarly well-timed addition to science. The best way of pointing
out the intimate connexion between these two branches of scien-
tific research, will be to mention the most important portion of
the discoveries of Fourier, and to shew how happily our col-
league had made choice of a subject for consideration.

Those portions of the mineral crust of the globe, which are
called sedimentary formations by geologists, have not been
formed all at once. The waters formerly covered, at different
times, regions at present situated in the centre of continents.
They deposited in them different kinds of rocks, in thin hori-
zontal beds. These rocks, although immediately superimposed
on each other like the layers of a wall, cannot be confounded
together : indeed their differences strike the most careless ob-
servers. I must also mention this most important fact, that
each formation has a distinct and perfectly defined limit, and
that no transition connects it with the superior formation.
Thus the ocean, the primary source of these deposits^ formerly
experienced, in its chemical composition, immense changes, to
which it is no longer subject in the present times.

With some rare exceptions, arising from local convulsions
whose effects are otherwise made manifest, the relative order of
the antiquity of the rocky beds which form the external crust
of the globe, is that of their superposition. The lowest were
the first formed. The attentive study of these different forma-
tions may assist us in tracing out the chain of events beyond
the most remote periods, and enlighten us on the character of
the frightful revolutions which periodically buried continents
under water or left them dry again.

The crystalline granitic rocks, on which the sea formed its
first deposits, have never exhibited any trace of organic beings.
These traces are only found in the sedimentary formations.

Vegetables appear to have formed the commencement of
organic life on the earth. Their debris are the only things met
with in the oldest beds deposited by water, and these belong to

M. Arago''s Historical Eloge of Joseph Fourier. ^97

plants of the most simple structure : ferns, reeds, and lycopo-
diums.

Vegetation becomes more and more complicated in the upper
formations. Finally, near the surface, it resembles the vegeta-
tion of the present continents, but with this very remarkable
addition, that certain vegetables which flourish only in the south,
such as large palm trees for instance, are found, in a fossil
state, in all latitudes, and even in the midst of the frozen regions
of Siberia.

In the ancient world, these northern regions must thus have
possessed, during winter, a temperature at least equal to that
which is experienced at present in the parallels where large
palm-trees begin to flourish. At Tobolsk there was the cli-
mate of Alicant or Algiers !

We shall discover fresh proofs of this mysterious result,
from an attentive examination of the dimensions of plants.

There are, at the present day, species of reeds, of ferns
and Lycopodiums, as well in Europe as in the Equinoctial
regions ; but it is only in warm climates that they are of great
dimensions. Thus, a comparison of the dimensions of the
same plants is, in fact, to compare, in reference to temperature,
the regions where they were produced. Well, place beside
the fossil plants of our coal formation, I do not say the analo-
gous European plants, but those which abound in those re-
gions of South America, the most celebrated for the richness of
their vegetation, and you will find the former incomparably
larger than the latter.

The Jbssil floras of France, England, Germany, and Scan-
dinavia exhibit, for instance, ferns nearly fifty feet high, and
with branches three feet in diameter, or nine feet in circum-
ference.

The Lycopodinece which, at the present time, in cold or
temperate regions, are creeping plants, scarcely rising above
the surface ; which, even at the Equator, under the most favour-
able circumstances, do not rise to more than three feet, reached
in Europe, in the ancient world, to the height of eighty feet.

One must be blind, not to see, in these enormous dimensions,
a new proof of the high temperature formerly possessed by our
country, before the last irruptions of the ocean.

S28 M. Arago''s Historical Eloge of Joseph Fourier.

The study of fossil animals is not less important. I should
be digressing from my subject, were I here to examine how
animal organization was developed on the earth, and what mo-
difications, or rather what complications it experienced after each
cataclysm ; or even if I should pause to describe one of those
ancient epochs, during which the earth, the sea, and the atmo-
sphere had only as inhabitants, cold-blooded reptiles of enor-
mous dimensions; turtles with shells ten feet in diameter;
lizards fifty-five feet long; pterodactyles^ true flying dragons,
of such singular shapes, that they have been placed, on well-
founded arguments, by turns among reptiles, mammalia, and
birds. The object I have in view, does not require such long
details, and one single remark will suffice.

Among the bones contained in those formations which are
the nearest to the present surface of the globe, there are those
of the hippopotamus, the rhinoceros, and the elephant. These
remains of animals peculiar to warm regions occur in all lati-
tudes. They have even been dicovered at Melville Island,
where the temperature falls at present to 50° below zero. In
Siberia, they are found in such abundance, that they have been
made an article of trade. Finally, on the steep shores which
border the Frozen Sea, vre no longer meet with mere fragments
of skeletons, but elephants quite entire, and still covered with
their flesh and skin.

I should be much deceived, gentlemen, if each of you had
not deduced from these remarkable facts, an inference also very
remarkable, and for which the fossil flora had already pre-
pared us, viz. that the polar regions of our globe have ex-
perienced an excessive cooling.

In explanation of this curious phenomenon, the cosmologists
do not assign any influence to possible variations in the inten-
sity of the sun ; and yet, the stars, those distant suns, do not pos-
sess that constancy of brightness which is commonly attributed
to them ; and some, in a pretty short time, have been reduced
to the hundredth part of their original intensity, whilst several
have totally disappeared. It has been thought preferable to
refer every thing to a heat proper to the earth or original, with
which the earth had been formerly furnished, and which had
been gradually dispersed.

t^

M. Arago's Historical Eloge of Joseph Fourier. 229

According to this hypothesis, it is evident, that the polar re-
gions may have possessed, during very ancient epochs, a tem-
perature equal to that of the equatorial regions where elephants
live at present, although they were deprived for whole months
of the sight of the sun.

It was not in explanation of the occurrence of elephants
in Siberia, that the idea of heat proper to the globe was for
the first time proposed. Some learned men had adopted it
before the discovery of any of these animals. Descartes thought
that originally (I quote his own expressions), the earth differed
in nothing from the sun, except that it was smaller. It would
thus be necessary to consider it as an extinct sun. Leibnitz did
this hypothesis the honour of appropriating it to himself. He
tried to deduce from it the mode of formation of the different
solid coatings of which our globe is composed. Buffbn also
gave it the influence of his eloquent authority. It is well
known that, according to this great naturalist, the planets of
our system are mere portions of the sun, which the stroke of a
comet had detached from it some thousands of years ago.

In support of this igneous origin of our globe, Mairan and
Buffon had already cited the high temperatures of deep mines,
and, among others, that of the mines of Giromagny. It ap-
pears evident, that if the earth was formerly incandescent, we
could not fail to find in the internal beds, that is to say, in
those which must have been the last to cool, traces of their ori-
ginal temperature. The observer, who, on penetrating into
the earth, did not find the heat increasing, might consider him-
self fully authorized to reject the hypothetical ideas oi Descartes^
Leibnitz^ Mairan, and Biiffbti. But is the reverse of this pro-
position equally certain ? May not the supplies of heat given
out by the sun for so many ages, have been distributed over
the earth, in such a manner, as to produce in it temperatures
increasing with the depth ? This is a vital question. Certain
minds easily satisfied, conscientiously believed that they had
solved it, by declaring, that the idea of a constant temperature
was by far the most natural ; but woe to the sciences if they
admitted such vague Considerations among the reasons for ad-
mitting or rejecting facts and theories ! Fontenelle would have
traced their horoscope in these words, so well fitted to humble
our pride, But whose truth, however, is developed on innu-

230 M. Arago's Historical Eloge of Joseph Fourier.

nierable occasions in the history of discoveries. " When a
thing may exist in two ways, it ahnost always does so in that
which at first seemed to us the least natural."

Whatever be the importance of these reflections, I hasten to
add that, instead of the weak arguments of his predecessors,
Fourier substituted proofs and demonstrations ; and it is well
known what these terms mean in the Academy of Sciences.

In all parts of the earth, on descending to a certain depth,
the thermometer no longer experiences any diurnal or annual
variation. It marks the same degree and the same fraction of
a degree, during the whole year, and during a continuance of
years. Such is the fact : what says theory ?

Suppose, for an instant, that the earth has constantly re-
ceived all the heat of the sun. Penetrate sufficiently into its
mass, and you will find, along with Fourier, by calculation, a
constant temperature for all periods of the year. You will
also find that this solar temperature of the lower beds varies in
different climates, and finally, that it ought to be always the
same in each country, provided you do not descend very low
in comparison to the radius of the earth. Well ! natural phe-
nomena are in manifest contradiction to this result. The ob-
servations made in a number of mines, and the observations
on the temperature of the water of spouting fountains rising
from different depths, have all given an increase of one degree
centigrade (P.S F.), for twenty or thirty metres (60 to 90 feet)
of depth. Thus, there was something incorrect in the hypo-
thesis which we discussed by following the steps of our colleague.
It is not true that the phenomena of temperature in terrestrial
beds can be attributed to the mere action of the solar rays.
This being proved, the increase of heat observable in all cli-
mates on penetrating into the interior of the globe, is a distinct
indication of heat proper to the globe. The Earth, as Descartes
and LeibJiitz alleged, but without being able to bring forward
any convincing argument, is at length shewn to be — thanks to
the numerous observations of natural philosophers and the
analytical calculations of Fourier — an encrusted Sun, whose
high temperature may be boldly appealed to, as often as it
is required for the explanation of ancient geological pheno-
mena.

After having proved that our earth possesses an original

M. Arago's Historical Eloge of Joseph Fouriei: 231

heat, not derived from the sun, and which, if we may judge
by the rapid increase shewn by observations, ought to be
powerful enough, at the trifling depth of from fifteen to twenty
miles, to fuse all known substances, the next question is to de-
termine what is its exact force at the surface of the earth ? what
amount should be attributed to it in estimating terrestrial tem-
peratures ? and what influence it exercises on the phenomena
of life ? According to Mairan, Buffon^ and Bailly^ this in-
fluence is immense. They estimate that, in France, the heat
disengaged from the interior of the earth is in summer 29
times, and in winter 400 times greater than what we receive
from the sun. Thus, contrary to the general opinion, the heat
of the heavenly body which gives us light, would only form a
very small portion of that, whose benign influence we experience.

This idea was ingeniously and very eloquently developed in
the Memoirs of the Academy ; in Buffoii's " Epoques de la Na-
ture ,•"" and in Baillifs letters to Voltaire on the origin of tJw
Scierices, and on the Atlantide. But the ingenious romance
of which it served as the basis, was dispersed like a shadow be-
fore the light of mathematics.

Fourier, having discovered that the excess of the total tem-
perature of the terrestrial surface, above that which would re-
sult from the mere action of the solar rays, has a necessary
and determinate relation to the increase of temperature at dif-
ferent depths, was able to deduce from the experimental
amount of this increase, a numerical determination of the ex-
cess in question. This excess is the thermometrical effect pro-
duced by the central heat at the surface ; now, in place of the
large numbers adopted by Mairan, Bailli/, and Biiff'an, what
did our fellow-member find it ? The thirtieth of a centigrade
degree ; not more.

The surface of the globe, which, originally, was probably in-
candescent, was thus cooled during the course of ages so as
scarcely to retain any perceptible traces of its original tempe-
rature. Nevertheless, at great depths, the original heat is still
excessive. Time will make a considerable alteration on the
internal temperature ; but at the surface (and the phenomena
at the surface are the only ones which can modify or aflect the
existence of living beings), all the changes are very nearly ac-

232 M. Arago's Historical Eloge of Joseph Fourier,

complished. The fearful congelation of the globe, whose
epoch was fixed by Bnffon at the instant the central heat shall
be totally dissipated, is thus a mere dream. At the surface,
the earth is affected only by solar heat. • So long as the sun
shall retain the same brightness, the human race, from pole to
pole, will find in every latitude the climates which allowed
them to settle and live there.

These, gentlemen, are great and magnificent results. In re-
cording them in the annals of science, historians will not ne-
glect to mention this singular peculiarity, that the geometrician
to whom we owed the first certain demonstration of the exist-
ence, in the interior of our globe, of a heat independent of the
solar influence, has reduced to nothing the immense share
which was attributed to this original heat, in the explanation
of the phenomena of terrestrial temperature.

To the merit of having freed the theory of climates from
an error which had kept its ground from being supported by
the imposing authority of Mairan, Bailly, and Biiffbn, Fourier
added the still greater merit d( introducing into this theory, a
consideration totally neglected before his time : he remarked
the influence which must be exercised by the temperature of
those celestial spaces^ amidst which the earth describes its im-
mense revolution round the sun.

On seeing, even at the equator, certain mountains covered
with eternal snow, and on observing the rapid decrease of tem-
perature in the strata of the atmosphere during ascents by the
balloon, meteorologists had supposed that excessive cold must
prevail in the regions which, from the extreme rarity of the
air, will always be unapproachable by man, and especially in
those beyond the limits of our atmosphere. It was not merely
by hundreds, but by thousands of degrees that they would
have measured it.

However, as usual, the imagination had passed all bounds.
The hundreds and thousands o^ degrees became, after the
strict examination of Fourier, only fifty or sixty degrees. Fifty
or sixty degrees below zero is the temperature maintained by
stellular radiation in the unbounded spaces traversed by the
planets of our system.

You all recollect, gentlemen, how fond Fourier was of expa-.

M. Arago's Historical Eloge of Joseph Fourier. 233

tiating on this result. You know how certain he felt of lia-
ving shewn the temperature of space to within eight or ten de-
grees. By what fatality has the memoir been lost, in which
our fellow member had doubtless given all the elements of this
important determination. May this irreparable loss at least
teach observers, that, ihstead of striving after an ideal perfection
which man cannot attain, they will act wisely in making the
public acquainted with their works as speedily as possible.

I should still have a great field to go over, if, after having
mentioned some of the problems whose numerical solutions the
state of the sciences allowed our learned fellow member to give,
I should enter into an analysis of all those which, being still
included within general formulae, only await the data of ex-
periment, in order to rank among the most curious acquisitions
of modern physics. The time at my command is not suffi-
cient for such illustrations. However, I should be guilty of
an unpardonable omission, did I not mention that, among
Fourier's formulae, there is one intended to give the amount of
the secular cooling of the globe, and to determine the number
of centuries which have elapsed since the commencement of
this cooling. The warmly disputed question as to the age of
our globe, including also its period of incandescence, is thus re-
duced to a thermometric determination. Unfortunately this
theoretical point is subject to serious difficulties. Besides,
the thermometric determination, on account of its excessive
minuteness, should be reserved for future ages.

I have shewn you the results of the relaxations of the Pre-
fect of Isere. Fourier still occupied this situation when Na-
poleon arrived at Cannes. His conduct, during this critical
time, has been the object of numberless misrepresentations. I
shall, therefore, fulfil my duty, by giving the facts, in all their
truth, as I heard them from the lips of our fellow member.

On the news of the Emperor's landing, the principal autho-
rities of Grenoble assembled at the prefecture. There, as Fourier
related, all present were occupied in considering, with much
ingenuity, and in great detail, the difficulties by which their
situation was surrounded. As for the means of overcoming them,
they seemed much more at a loss. There was not much confi-
dence placed at that time in administrative eloquence. It was

VOL. XXVI. NO. LIT.— APRIL 1839. Q.

234 M. Arago^s Historical Eloge of Joseph Fourier,

therefore decided to have recourse to proclamations. The Ge-
neral in command and the Prefect each brought forward a pro-
posal. The assembly was discussing their views minutely,
when an officer of the gendarmerie, an old soldier of the impe-
rial armies, rudely exclaimed : " Gentlemen, make haste ; other-
wise any deliberation will be useless. Trust me, I speak from
experience ; Napoleon always follows very quickly after the
couriers who announce him." Napoleon in fact arrived imme-
diately. After a slight hesitation, two companies of sappers
who had been dispatched to break down a bridge, joined their
former General. A battalion of infantry soon followed this
example. Finally on the ^Zam itself, and in the presence of
the multitude who thronged the ramparts, the entire 5th regi-
ment of the line put on the tricoloured cockade, substituted
for the white ensign the eagle which it had preserved and
which had witnessed twenty battles, and set oiF with cries of
Vive VEmpereur ! After such a commencement, any attempt
to keep the field would have been madness. General Mar-
chand, therefore, caused the gates of the town to be shut. He
still hoped, notwithstanding the evidently hostile dispositions
of the inhabitants, to be able to sustain a regular siege, merely
with the assistance of the 3d regiment of engineers, the 4th of
artillery, and some small detachments of infantry, who had not
abandoned him.

From this instant, the civil authority had ceased. Fourier,
therefore, thought it his duty to quit Grenoble, and go to
Lyons, where the Princes had arrived. At the second re-
storation, this departure was imputed as a crime against him ;
and he narrowly escaped being tried for the offence.

Certain persons alleged that the presence of the Prefect in
the chief town of Isere would have assuaged the storm ; and
that the resistance would have been more spirited and better
directed. They forgot, however, that in no place, and still
less at Grenoble than any Avhere else, could even a shadow of
resistance be attempted.

Let us see, then, how the capture was effected of this fortified
town, whose fall, it is said, would have been prevented by the
mere presence of Fourier. It is eight in the evening. The
inhabitants and soldiers line the ramparts. Napoleon proceeds

M. Arago's Historical Eloge of Joseph Fourier. 235

a few steps in advance of his little band ; he goes to the very
gates and knocks, (do not be alarmed, gentlemen, it is not a
battle which I am going to describe), he knoclcs with his snuff-
hoxl "Who is tliere ?" cries the officer on guard. " It is the
Emperor, open !" " Sire, my duty forbids." " Open, I tell you ;
I have no time to lose."" " But, Sire, even although I should
wish to open for you, I could not : the keys are with General
Marchand.'' " Go then and seek them." " I am certain he
will refuse me them." *' If the General refuses them, tell him
that J dismiss him'''' !

These last words electrified the soldiers. For two days
hundreds of proclamations had described Bonaparte as a wild
animal which must be caught at all hazards. They com-
manded every body to fall upon him ; and yet this man
threatened the General with dismission ! The single word dis-
miss destroyed the feeble line of demarcation, which for an
instant separated the old soldiers from the young recruits;
one word gained over the whole garrison to the Emperor's
interest.

The circumstances connected with the capture of Grenoble
were not yet known, when Fourier arrived at Lyons. He
brought with him the news of Napoleon's rapid march, and of
the defection of two companies of sappers, a battalion of infan-
try, and of the regiment commanded by Labedoyere. Besides,
he hadj, on his road, witnessed the warm sympathy of the
peasantry for the proscribed of the Island of Elba.

The Count d'' Artois received the P'refect and his communi-
cations very ill. He declared that Napoleon's arrival at Gre-
noble was not possible, and that no rehance ought to be placed
on the disposition of the peasantry. As for what might have
taken place, said he, in your presence, at the very gates of the
town ; as to the tricoloured cockades substituted for the cockade
of Henry IV ; as to the eagles which are supposed to have re-
placed the white flag, I do not doubt your word, but you
must have been bewildered by anxiety. Return, Sir, without
delay to Grenoble; you answer to me for the town with your
head.

You see, gentlemen, after having so long proclaimed the ne-
cessity of speaking the truth to princes, moralists will act
wisely if they will endeavour to persuade pr^ices to listen to it.

236 M. Arago's Historical Eloge of Joseph Fourier.

Fourier obeyed the order he had just received. He had
only proceeded a very short distance in the direction of Greno-
ble, when he was arrested by some hussars and taken to the
head quarters at Bourgoin. The Emperor, who was at the time
stretched out on a large map with a pair of compasses in his
hand, said, on seeing him enter, " Well, Prefect I did you also
declare war against me P"*" " Sire, my oaths rendered it my duty
to do so."" " A duty did you say ? and do you not see that in
Dauphiny no one is of your opinion ? Do not suppose, how-
ever, that your plan of operations frightened me much. I
was only sorry to see among my adversaries, an Egyptian^ a
man who had eaten bread with me whilst bivouacking, — an
old friend.""

It pains me to add, that after these kind words came the fol-
lowing : " How, moreover, could you forget, M. Fourier, that I
have made you what you are ?"

You will regret along with me, gentlemen, that a timidity,
so natural in the circumstances of the case, prevented our fel-
low-member from protesting immediately and forcibly against
this confusion, which the powerful of the earth continually
wish to establish between the perishable goods of which they
are the dispensers, and the noble fruits of the intellect. Fou-
rier was Prefect and Baron through the Emperor : he was one
of the glories of France through his own genius.

On the 9th March, in a moment of passion, Napoleon, by a
decree dated from Grenoble, ordered Fourier to quit the terri-
tory of the 7th Military ^Division within five days, under pe-
nalty of being arrested and treated as an enemy of the nation.
The next day our fellow-member left the conference of Bour-
goin with the office of Prefect of the Rhone and the title of
Count, for the Emperor still bestowed honours in this manner
after his return from Elba.

These unexpected testimonials of favour and confidence were
little relished by our fellow-member ; but he did ndt dare to
refuse them, although he saw quite distinctly the immense im-
portance of the events in which chance called him to enact a
part.

What do you think of my enterprise ? said the Emperor to
him on the day of his departure from Lyons. Sire, replied
Fourier, I believe that you will fail. If one fanatic is met with

M. Arago's Historical Eloge of' Joseph Fourier. 237

on your road, it is all over with you. Bab, exclaimed Napo-
leon, the Bourbons have nobody on their side, not even a fana-
tic. Apropos, you have seen in the newspapers that they have
put me out of the protection of the law : I shall be contented
with putting them out of the Tuileries.

Fourier only retained the office of Prefect of the Rhone till
the 1st of May. It has been said and published that he was
recalled for refusing to become an accomplice in the acts of
terrorism which the ministry of the Hundred Days prescribed
for him ! The Academy will find me on every occasion happy
to collect and record the actions, which, by honouring its mem-
bers, shall confer additional renown on the entire body. I even
feel that, in this respect, I might be inclined to be a little cre-
dulous. On this occasion, the most rigorous examination was
required of me. If Fourier did himself honour by refusing to
obey certain orders, what must we think of the minister of the
interior, from whom these orders emanated ? Now, I must
not forget that this minister was also an academician, illustrious
for his military services, distinguished for his mathematical
works, and esteemed and beloved by all his fellow-members.
Well, gentlemen, you will share in my satisfaction when I de-
clare, that, after the most scrupulous examination into all the
acts of the Hundred Days, I have discovered nothing which
ought to lessen the sentiments with which you regard the me-
mory of Carnot

On losing his office of Prefect of the Rhone, Fourier came to
Paris. The Emperor, who was on the point of setting out for
the army, perceived him in the crowd at the Tuileries, accosted
him in a friendly way, informed him that Carnot would explain
to him why his recall from Lyons had become unavoidable, and
promised to attend to his interests whenever he could obtain
some leisure from military affairs. The second restoration
found Fourier in the capital, without employment, and naturally
uneasy about his future prospects. He who, for fifteen years,
governed a large department, who had the direction of such
expensive works, who, in the affair of the marshes of Bourgoin,
had to stipulate for so many millions of francs with private in-
dividuals, communes, and companies, had not a capital of twenty
thousand francs. This honourable poverty, together with the

238 M. Arago's Historical Eloge of Joseph Fourier.

recollection of the most important and glorious services, was
not likely to affect ministers, at that time under the influence
of political passions and the caprices of foreigners. A petition
for a pension was, therefore, refused with harshness. Do not
be alarmed ! France will not have occasion to blush for having
left one of her greatest men in want. The Prefect of Paris,
M. de Chabrol, learns that his old professor at the Polytechnic
School, the Perpetual Secretary of the Institute of Egypt, the
author of the Analytical Theory of Heat, is about to be reduced
to the necessity of giving instructions for his subsistence. This
news grieves him ; he shews himself regardless of party cla-
mour, and Fourier receives from him the chief charge of the
Bureau de la Statistique of the Seine, with a salary of 6000
francs. I have thought it right, gentlemen, not to suppress
these details. The sciences may shew gratitude towards all
those who give them support and protection when there is any
danger in doing so, without fearing that the burden should
ever become too heavy !

Fourier made a suitable return for the confidence of M. de
Chabrol. The memoirs with which he enriched the interesting
volumes published by the Prefecture of the Seine, will hence-
forth serve as a guide to all those who have the good sense to
see in statistics something more than a crude mass of figures
and tables.

The Academy of Sciences seized on the first opportunity
which offered to include Fourier among its members. On the
S7th of May 1816, it named him academician. This election
was not confirmed. The endeavours, the sohcitations, and the
prayers of the inhabitants of Dauphiny, who were then in
Paris, had almost prevailed with the authorities, when a courtier
exclaimed that they were going to grant an amnesty to the Lor-
hedoyere civil ! This word, for during many ages the human
race has been governed by words, decided the fate of our fel-
low-member. From political motives, the ministers of Louis
XVIII decreed that one of the most learned men of France
should not belong to the Academy ; and that a citizen, the
friend of all the distinguished persons in the capital, should be
publicly disgraced.

In our country absurdity does not last long. Thus, in

M. Arago's Historical Eloge of Joseph Fourier. 239

1817, when the Academy, without allowing itself to be dis-
couraged by the bad success of its first attempt, unanimously
named Fourier to the place which had just become vacant in
physics, the royal assent was obtained without difficulty. I
ought to add, that very soon afterwards, the government, hav-
ing got rid of their dislike, frankly and unreservedly approved
of the happy choice which you made of the learned geometri-
cian, to replace Delambre as Perpetual Secretary. 1'hey even
went so far as to wish to entrust him with the direction of the
fine arts ; but he had the good sense to refuse.

On the death of Lemontey, the French Academy in which
Laplace and Cuvier already represented the sciences, enrolled
Fourier amongst its members. The literary titles of the most
eloquent fellow-labourer in the work on Egypt were indisput-
able : they were not even disputed ; and yet this nomination
caused violent debates in the newspapers, which deeply afflicted
our fellow-member. But was not this rather a question as to
whethej these double nominations are useful ? Might it not
be alleged, without being guilty of a paradox, that they extin-
guish among youth an emulation which we are bound in duty
to encourage ? Besides, what would become of that unity so
much boasted of by the old Academy, if there were double,
triple, and quadruple memberships ? 'rhe public at last would
only discover it in the unity of the dress.

Whatever truth there may be in those reflections, and I
hope you will correct them if 1 am wrong, I hasten to re-
peat that the academical titles of Fourier were not even the
subjects of a doubt. The applause which had been lavished
on the elocjuent elopes of Delambre^ Bregiiet^ Charles^ and Her-
schel^ proved sufficiently, that if their author had not been al-
ready one of the most distinguished members of the Academy
of Sciences, the public would have unanimously called him to
take his station among the arbiters of French literature.

Fourier at length restored, after so many reverses, to his fa-
vourite occupations, passed the last years of his life in retire-
ment, and in the fulfilment of his academical duties. Conver-
sation had become the chief part of his occupation. Those
who thought they had just cause for blaming this, doubtless
forgot, that constant reflection is no less strictly forbidden to

240 M. Arago's Historical Eloge of Joseph Fourier,

man, than the abuse of the physical powers. Repose, in every
case, refreshes our frail frame ; but it is not every one
that can obtain repose who desires it. Examine your own
thoughts., and say if, when jou are investigating some new
truth, gaiety or conversation, or even sleep, have the effect of
diverting your attention ? Fourier^'s shattered constitution re-
quired much care. After many trials, he found, that the only
means of freeing himself from the exhausting intensity of his
thoughts, was to speak in a loud tone on the events of his life,
on his scientific works, in progress or finished, and on the
wrongs of which he had to complain. Every one remarked,
how slight was the share of the conversation allotted by our
talented fellow member, to those who were in habits of familiar
intercourse with him : the reason for it will now be understood.

Fourier had preserved, in his old age, the grace, the ur-
banity, and the varied information which, a quarter of a cen-
tury previously, gave such charms to his lectures at the Poly-
technic School. People even took pleasure in hearing him re-
count an anecdote which they knew by heart, or events in which
they themselves had enacted a part. Chance once made me a
witness of the sort o^Jascination which he exercised on his audi-
tors, in a circumstance which, T think, deserves to be known,
for it will shew, that the term I have just made use of is not
too strong.

We were seated together at the same table. The guest from
whom I separated him, was an old officer. Our fellow mem-
ber was informed of it, and the question, — '' Have you been
in Egypt.?" served as a commencement to the conversation.
The reply was in the "affirmative. Fourier hastened to add, —
" As for myself, I remained in that magnificent country until
it was entirely evacuated. Although unacquainted with the
trade of war, I fought in the midst of our soldiers against the
insurgents of Cairo, and had the honour to hear the cannons at
Heliopolis.''^ From that, to recounting the battle, was an easy
transition. It was immediately done, and you had immediately
before you, four battalions in squares, forming in the plain of
Quobbeh, and manoeuvring with admirable precision under the
orders of the illustrious geometrician. My neighbour, all at-
tention, his eyes fixed, and neck bent forward, listened to this

M. Arago's Historical Eloge of Joseph Fourier. S41

recital, with the deepest interest. He did not lose a syllable
of it, and one might have been positive that it was the first
time he had heard of these memorable events. So deHghtful
is it, gentlemen, to please, that on remarking the effect he had
produced, Fourier reverted in a still more detailed manner to
the chief battle of these great days ; to the taking of the forti-
fied village of Mattaryeh ; ito the passage of two small columns
of French grenadiers, through trenches filled with the dead
and wounded of the Ottoman army. " Ancient and modern
generals have sometimes spoken of similar feats,"" exclaimed our
fellow member, " but it was in the hyperbolical language of
bulletins. In this instance the fact is substantially correct ;
it is as true as geometry." " I feel, however,'' added he, " that
it will require all my assertions to induce you to believe it."

*' Set your mind at rest on that point,*" replied the officer,
who seemed that instant to awake from a long dream, " Were
it necessary, I could vouch for the accuracy of your description.
It was I who, at the head of the grenadiers of the 13th and
15th demi-brigades, crossed the entrenchments of Mattaryeh,
by passing over the dead bodies of the Janissaries.'^

My neighbour was General Tarayre. It will be more easy
to imagine, than for me to describe, the effect of the few words
which had just escaped him. Fourier stammered out apolo«
gies, whilst I reflected on that seduction, that power of lan-
guage, which, for nearly half an hour, had made the celebrated
General forget the part he had played in tlie gigantic conflicts
which were being described to him.

The more your secretary found it necessary to talk, the
greater aversion did he exhibit to verbal discussions. Fourier
cut short every debate, when it became evident, that there
was a marked difference of opinion, intending to resume the
same subject afterwards, and with the modest design of mak-
ing a slight advance each time. Some one asked Fontaine^
the celebrated geometrician of this academy, what he did in
society, where he remained almost perfectly silent. " I study j*^
replied he, " the vanity of men, in order to mortify it occa-
sionally.*' If, like his predecessor, Fourier also studied the
base passions which strive after honours, riches, and power, it
was not in order to struggle with them. Being resolved to

24?^ M. Arago's Historical Eloge of Joseph Fourier.

have nothing to do with them, he laid his plans so as never to
encounter them. How different is this from the ardent and
impetuous character of the young orator of the popular society
of Auxerre ; but what would be the use of philosophy, if it
did not teach us to conquer our passions ! It was only occa-
sionally that Fourier's real character shewed itself. " It is
strange," said, one day, a certain very influential person belong-
ing to the court of Charles X., whom the servant, Joseph^
would not allow to get farther than our fellow member's ante-
chamber, " it is really strange that your master should be
more difficult of access than a minister I " Fourier overhears
the remark, jumps out of bed, to which he was confined by
indisposition, opens the room door, and, facing the courtier,
exclaims, " Joseph^ tell the gentleman, that if I were minister
I should receive every body, because such would be my duty;
as a private individual I receive whom I think fit, and when I
think fit."' The grandee, disconcerted by the liveliness of the
sally, did not answer a word. We must even suppose, that
from that instant he determined to visit nobody but ministers,
for the simple savant heard no more of him,

Fourier possessed a constitution which promised him long
life; but of what avail are natural powers against the un-
healthy customs in which men indulge ! To get quit of slight
rheumatic attacks, our fellow member put on even more cloth-
ing during the warmest season of the year, than travellers con-
demned to pass the winter amid polar ice. " I am reckoned
stout,'' he used sometimes to say, with a smile; " but believe
me, this opinion is far from the truth. If, like the Egyptian
mummies, I were subjected, which God forbid, to the process
of unrolling, the only residue would be a very lank body." I
might add, taking my term of comparison also from the banks
of the Nile, that in Fourier's apartments, which were always
small, and strongly heated, even in summer, the currents of air
to which one was exposed near the doors, sometimes resembled
the terrible simoon, — that burning wind of the desert, which
the caravans dread as much as the plague.

The medical advice of his old and constant friend M. Larrey,
did not succeed in inducing him to modify this fatal regimen.
Fourier had already had, whilst in Egypt, and at Grenoble,

M. Arago's Historical Eloge of Joseph Fourier. 243

some serious attacks of aneurism of the heart. At Paris it was
scarcely possible to mistake the primary cause of the frequent
choking sensations which he experienced. However, a fall
which he had, on the ^th May 1830, whilst descending a stair,
brought the malady to a much more rapid termination than
could ever have been expected. Our fellow member, in spite
of earnest entreaties, persisted in his determination only to try
patience, and a high temperature, as remedies for the most
threatening symptoms. On the 16th May, about four p. m.,
Fourier experienced, in his study, a violent crisis, but without
being at all aware of its danger ; for, after throwing himself on
a bed, without undressing, he requested M. Petit, a young
physician and one of his friends, who was attending him, not
to go away, " In order," said he, *« that we may have a little
conversation together presently." But almost immediately
after these words, he cried out, " Quick, quick — vinegar — I am
fainting !" and one of the learned men, who had shed the
greatest lustre on the Academy, had ceased to exist.

This melancholy event is too recent, gentlemen, to render
it necessary here to recall, both the profound grief which the
Institute experienced on losing one of its brightest ornaments,
and the funeral solemnities in which so many persons, generally
separated by interests and opinions, united together with a
common feeling of veneration and regret, around the inanimate
remains of Fourier ; and the Polytechnic School joining the
procession, en masse, to do homage to one of its oldest and most
celebrated professors ; and the words which, on the brink of
the grave, so eloquently described the profound mathematician,
the intellectual author, the upright governor, the good citizen,
and the devoted friend. We may merely remark, that Fourier
belonged to all the great learned societies in the world, and
that these, joined with the most affecting unanimity in the
grief of the Academy, or rather the grief of all France, — a
splendid evidence that the republic of letters is now-a-days
something more than a mere name. What is there, then,
awanting in respect to the memory of our fellow member ? — a
successor better adapted than myself, to group together, and
exhibit in relief the different phases of a life so varied, so la-
borious, and so gloriously connected with the greatest events of

244 Professor Kaemtz on the more imporiaiit

the most memorable epoch of our history. Fortunately the
scientific discoveries of the illustrious Secretary had nothing to
dread from the incapacity of his panegyrist. My end shall
have been completely attained, if, notwithstanding the imper-
fection of my sketch, I have proved to each of you, that the
progress of general physics, of terrestrial physics, and of geo-
logy, will daily exhibit more and more the numerous applica-
tions of the Analytical Theory of Heat, and that this work will
hand down the name of Fourier to the latest posterity.

Remarks on the more important Atmospherical Phoenomena. By
Professor Ludwig Friedrich Kaemtz of Halle.

Importance of Meteorology. — It is impossible for organic be-
ings to exist unless they are surrounded by the atmosphere. As
an animal, under the receiver of an air-pump, dies when the air is
sufficiently exhausted, so a plant, placed in similar circumstances,
cannot thrive. It is not merely the presence of the constituent
parts of the atmosphere which is requisite for these beings, for
there are other relations which possess great influence in this re-
spect, and of these! would adduce more especially the temperature
and motion of the aerial ocean. Just as each plant is in a flour-
ishing condition only when it inhabits a certain region, and be-
comes more or less diseased when exposed to the influence of
too high or too low a temperature, so we find, that every ani-
mal inhabits certain regions of the earth. Although man,
owing to the pliability of his nature, possesses to a greater
degree than any plant the power of accommodating himself to
all climates, although he can endure the burning heats of the
deserts of Africa and Asia, and the piercing cold of high nor-
thern latitudes ; yet minute investigations show differences, not
merely in the corporeal condition (especially when we keep in
view the prevailing diseases as the groundwork of the examina-
tion), but also in the occupations and the mental powers ; diffe-
rences which we must explain chiefly by the position of the dis-
tricts inhabited by him, by their peculiar climate, and also the
tone of intellect thus produced.

It is not merely these inequalities of climate in different dis-
tricts, which, since the beginning of history, have attracted the

Atrnospherkal Phcenomena. 245

attention of mankind, but still more the changes which take
place in the same place, — the oscillations of the mean relations
of the weather. There is no portion of human knowledge in
which we find so many more or less different or contradictory
views as in meteorology, and the phenomena themselves are
more complicated than in almost any other department of the
natural sciences; the appearances which succeed one another stand
in such intimate connection, that the very one which was the con-
sequence of previous phenomena becomes also the cause of future
variations ; and hence it happens that the weather, which we re-
mark at any moment at the place we inhabit, is not only acted
on by causes which are in activity at one particular position,
but also that the weather of every other portion of the earth ex-
ercises a greater or less influence on it. The great multitude of
elements, which must be kept in view according to what we have
just said, increases to a great extent the difficulty of investigat-
ing the isolated phenomena; and although during the last
twenty or thirty years treatises have appeared, which in excel-
lence leave far behind the works of the earlier natural philoso-
phers, yet we ought only to regard the results obtained, as the
foundations of a building, which still remains to be erected in
due and harmonious proportions in time to come. The object
of the following pages is to communicate the more important
meteorological laws, and I hope they may have the effect of ex-
citing natural philosophers more and more to continued obser-
vations, and to the publication of the laws deduced from them.
Temperature of the Atmosphere. — The most important cause
of all meteorological phenomena is the sun, and this is owing
to the warming power of its rays ; were the sim merely
an attracting body without luminous rays, the temperature
of the whole earth would be equal, and the alternation of
heat and cold in the course of the day and the year would
disappear. The intensity of the action of the sun is not
alike every-where or even at the same place at different times,
inasmuch as that depends on the height of the heavenly body
above the horizon of the place of observation. If we imagine
a cylindrical bundle of parallel rays of the sun, it will possess
at all times the same heating power ; if we intersect it by plane
surfaces under different angles of inclination, the cutting sur-
face is the smallest when it stands at right angles to the axis of

S46 Professor Kaemtz on the more important

the cylinder, and it becomes larger the smaller the angle is
which it forms with the axis ; the heating of such a surface will
in the first case be much more considerable than in the second.
Analysis points out the law of this heating under different
angles of inclination, and without dwelling on the subject, I
would remark, that it follows from what has been said, that the
temperature of the soil, and of the strata of air lying next it,
must be so much the higher the greater the height of the sun
above the horizon. Hence not merely is the heat at every place
greater at the time of noon than in the morning and evening,
but also the equinoctial regions are warmer than the countries
lying near the pole.

The simple mathematical law, indicated by the relation be-
tween the heating power and the height of the sun, is modified
in a variety of ways. Although the atmospheric air is an ex-
tremely transparent body, yet, even in its purest condition, it
does not allow all the rays to penetrate which reach it. It is
itself lighted by them, and these rays reflected from the parti-
cles of air, are the cause that the visible firmament does not ap-
pear perfectly dark. Even under the most favourable circum-
stances, of one hundred rays falling in our regions on the at-
mosphere, from the sun when it is in a vertical position, only about
eighty reach the surface of the earth ; and then, besides, a con-
siderable portion of the heat is at the same time lost in the upper
strata of the atmosphere. As each particle of air takes a por-
tion of heat from the sun's ray by which it is encountered, so
the diminution of temperature arising from this cause will be
so much the greater the longer the journey is that these rays
have to perform through the air ; and as the space to be tra-
versed is much greater when the sun's height is inconsiderable
than when it is more elevated, sf:>, for this reason, the difference
of heat when the sun is low and high will be still more increased.

The nature of the surface of the earth has a very great in-
fluence on the degree of heat communicated. Thus, dry, loose,
rolled masses, such as we meet with in the sandy deserts, con-
duct the heat slowly through themselves. Although also the
uppermost layers may be strongly heated by the sun, yet, at
an inconsiderable depth, we meet with a heat which is but little
removed from the mean temperature of the year. Hence in
warm summer days, where perhaps the temperature of the air

Atmospherical Phoenomena. ii47

in the shade is not more than 30° of the centigrade thermome-
ter (86^ Fahr.), we find that a superficial layer of dark sand has
acquired from the sun a temperature of 50° C. (122° Fahr.), or
more. If, on the other hand, the surface consists of water, all
the rays are not absorbed by it ; a large portion penetrates into
the interior of the mass, and thus the latter also, and not merely
the superficial layer, is heated. Hence in summer the tempe-
rature of water during the day is never so elevated as that of
the neiglibouring land. In addition to the cause mentioned,
there are others which arise from the nature of water. Al though
the uppermost layer is somewhat more strongly heated than
those which lie at a small depth beneath, yet when this heating
takes place evaporation ensues, which increases with the tem-
perature, and thus the uppermost portions are cooled, acquire
a greater density than the layers beneath, and sink down, while
others reach the surface, soon afterwards to sink in their turn.
These unceasing movements are the cause that the uppermost
portion of water possesses by day an uniform temperature, but
one that is lower than that of the surface of the solid land, and
this difference necessarily shews itself in the strata of air in con-
tact with it.

But it is not only the various conducting powers and the dif-
ferent states of aggregation that are causes of the differences
between land and sea ; there are also vapours floating in the at-
mosphere whose effects must be taken into consideration. Since
a rapid evaporation ensues over large collections of water, the
atmosphere must contain a much larger quantity of vapour,
under such circumstances, than where it is over dry land. Were
the latter always in a liquid state it would exercise no influence
on the power of the sun's rays, nay it seems probable that a
mcHst atmosphere has less effect than a dry one in diminishing
the light of the sun. But when there is much vapour present,
the upper strata of the atmosphere especially are easily satu-
rated.; clouds are formed, which diminish the influence of the
sun on the ground, or masses of rain fall, which communicate
the lower temperature of the upper portions of the atmosphere
to the surface of the earth, and contribute to the cooling of the
latter, a phenomenon which necessarily must take place much
more rarely in the case of dry solid land.

What has hitherto been said refers merely to the changes

S48 Professor Kaemtz on the more important

of temperature which take place during the day. If the sun
is under the horizon, the source of heat is removed, and the^
earth is cooled, inasmuch as its surface radiates to the sky the
heat acquired by day, and hence the heat is diminished during
the whole night, till at length, some time before the rising of
the sun, warmth again arrives accompanying the rays of light of
the dawn. It is the superficial thin layer of the earth''s surface
which first loses its heat in this manner ; it is cooled at last to
a lower point than the portion beneath, which during the day
had acquired heat by conduction, and, as an exchange now
ensues between the two, the cooling is less considerable than it
would have been, did that exchange not take place.

We have to take into consideration the same circumstances
in the night cooling, as in the action of the sun. If the ground
is a bad conductor of heat, the communication between the
upper and the more deeply situated layers takes place but
slowly, and the same places in which the heating during the
day was so considerable are also remarkable for their cooling
during the night. But it is quite diff'erent with regard to very
large masses of water. The uppermost portions are hardly
cooled when they sink down, owing to their greater specific
gravity ; warmer portions take their place, which in a short
time meet with the same fate, and thus the cooling during the
night is just as inconsiderable as the heating during the day.
Owing to the occurrence of clouds which is so very frequent, this
decrease of heat is still further diminished. As the clouds act
like a screen and diminish considerably the radiation by night,
the decrease of heat is smaller ; and just as cloudy days in sum-
mer are much colder than clear ones, so obscure nights are
Avarmer than clear ones.

What has been said of the changes that occur in the course
of the day, also holds good as to the variations which take
place in the course of the year. In the interior of a continent
the difference between the heat of summer and winter is much
greater than it is on the sea-coast; nay, so remarkable is this fact,
that, in passing from the west coast of Europe to the interior,
the increase of this difference can be traced almost step by step.

Rise and Fall of the Barometer explained. — Without fol-
lowing up more deeply the above propositions, or forming
conclusions regarding the resulting form of the isothermal

G

H

M

«

Atmospherical Phenomena. 249

lines, I shall now turn to some facts which we have almost
every moment an opportunity of observing. Although the
density of the air becomes less at every step we ascend,
and to such an extent that, at a height of about ten miles, it is
less than we are able to make it under the receiver of a good
working air-pump ; yet, for the sake of simplicity, we may as-
sume that the upper limit of the atmosphere is just as distinct-
ly marked out as we find it
in liquid bodies. Let, then,
AB be a portion of the earth's
surface represented as level,
and let it have every-where
the same temperature ; and
farther let this uniformity ex-
tend to all points which are
at an equal distance from the ground ; then CD, the upper sur-
face of the atmosphere, would be parallel to AB, and we should
always find at an equal height the same density, the whole mass
would be still, and at whatever point on AB we should suspend
a barometer, it would always indicate the same pressure of the at-
mosphere. This state of equilibrium, however, is changed, when-
ever the temperature above one portion of the earth's surface be-
comes greater than that over another. Supposing that EF and
the air occurring above it were much more strongly heated than
AE and BF, then, owing to the expansion of the air thus pro-
duced, the boundary of the atmosphere is removed to G H ;
but, according to the laws of mechanics, an equilibrium can no
longer exist under these circumstances, the air flows in the up-
per strata in the direction of IK and ML from the warmer to
the colder region, until the surface of the atmosphere is again
parallel to the ground ; and, hence necessarily, the barometer
sinks where the heating has taken place, and rises where the
temperature remained unaltered. This altered pressure of the
atmosphere causes also a movement in the lower strata of the
air. For since over AE and FB, the vertical, and henc«
also the lateral pressure of the atmosphere is greater than over
EF, currents of air arise near the ground from the colder to
the warmer region.

The consequence is the same when the temperature above
EF remains unchanged, while AE and FB are unusually

VOL. XXVI. KO. LTI.— APRIL ISSQ- E

250 Professor Kaemtz on the more important

cooled. Both these phenomena are much more striking, when
EF is heated, and AE and FB are cooled, at the same time.

From the foregoing, the following two laws may be deduced,
and they are among the most important in the whole range of
Meteorology : —

1. If two neighbouring parts of the earth have unequal tem-
peratures, we find that, in the upper regions of the atmosphere,
there are winds which blow from the warmer to the colder
part, while, near the surface of the earth, there are winds from
ihe colder to the warmer portion.

2. When a tract of the earth is unusually heated, or if it is
distinguished from the neighbouring regions by a high tempe-
rature, the barometer sinks ; but if, on the other hand, its
temperature is unusually low, the pressure of the atmosphere
increases.

Winds. Sea and Land Breezes. — These two laws just men-
tioned, which follow from the simplest principles of mechanics,
are abundantly confirmed by experience. If, for the present, we
confine ourselves to the first, we find a proof of its truth in the
land and sea breezes, that is, those winds which, on the coasts,
and especially between the tropics, blow during the day from the
colder sea to the warmer land, and during the night from the
colder land to the warmer sea, and also in the frequently very
violent gusts of wind which proceed in all directions from a
thick storm-cloud. But the trade winds between the tropics
are the most remarkable proofs of this law.

Trade- Winds. — Over both the great oceans extending from
pole to pole, there blows, during the whole year, with very rare
exceptions in low latitudes, a regular east wind ; this wind is in
general north-east in the northern hemisphere, and south-east in
the southern hemisphere; its polar limits lie between latitude SO"
and 30°. Near the equator, there is a zone where there are no re-
gular winds, and where calms alternate with violent tempests. It
is here that the masses of air rise from the surface to the higher
regions, and cause a powerful ascending stream of air. The
first voyagers who ventured far into the Atlantic Ocean, Co-
lumbus, Vasco de Gama, &c., were not a little astonished at the
great regularity of the east wind, which was a great assistance
to them in their voyage towards the new world, but seemed to
them just as great a hindrance duwng their return to Europe,

Atmospherical Phenomena. 251

For a long time the cause of this wind was unknown, until at
length it was shewn by Halley to depend on the difference of
temperature between lower and higher latitudes.

The difference of temperature between the equinoctial re-
gions and those of higher latitudes, causes, in the upper parts
of the atmosphere, currents of air from the equator to the poles,
while, near the surface, these currents have an opposite di-
rection. If the earth were a motionless body, then, on the sur-
face of the sea, where there are no mountains or other similar ob-
structions presenting obstacles to the air currents, north winds
would blow in one hemisphere, and south winds in the opposite ;
but this direction is somewhat altered by the rotation of the earth.
For when the masses of air approach the equator, they do not
immediately participate in the more rapid movement of the re-
gions which they reach ; and as they remain behind, they op-
pose an obstacle on the east side of the bodies which occur on
the surface, and which are moving from west to east. By the
union of this direction with that coming from the pole, we get
a north-east wind for the northern hemisphere, and a south-
east wind for the southern hemisphere. But the motion of the
earth has an influence not only on the lower currents of air,
but also on the upper equatorial current ; for when this reaches
higher latitudes, it comes into regions in which the rapidity
of rotation is less ; hence the current of air hastens on before
the earth"'s surface, and we thus meet with a south-west wind
in the northern hemisphere, and a north-west wind in the
southern.

The facts which have been communicated by navigators for
centuries, confirm these theoretical conclusions ; and -we find
not merely the trade-winds as the theory requires, but we also
find that the intermediate space, by which the south-east and
north-east trade-winds are separated, changes simultaneously
with the sun from north to south. Although, in the regions
where the trade-wind blows with regularity, the sky is almost
always serene, so that it is difficult to determine the condition
of the upper current of air by means of the course of the
clouds, yet we see, nevertheless, that the light small clouds,
which occasionally appear in the upper strata of the atmosphere,
for the most part move against the trade-wind ; thus, on the
ummit of the peak of Teneriffe, a more or less strong westerly

I?52 Professor^ Kaemtz on the more important

wind is generally met with, while below, the trade-wind blows
with regularity. The existence of the west wind in the upper
strata of the air is further proved by the following fact : — In
the island of Barbadoes, which lies on the eastern edge of the
Antilles, the inhabitants, while the usual trade-wind was blow-
ing, were not a little astonished at volcanic ashes being brought
by it. Some time afterwards they heard that these were de-
rived from the volcano situated on the island of St Vincent,
which is to the west. These ashes had undoubtedly been
transported in the upper strata of the atmosphere beyond Bar-
Imdoes, and during their descent had again come into the region
of the trade-wind.

But not only do the trade- winds prove the production of
winds by differences of temperature in different places ; the
monsoons also in the Indian Sea, as well as the north winds,
which, especially during summer, blow in the Mediterranean
Sea and on the north coast of Africa, afford the most satisfac-
tory evidence of the accuracy of this view of the subject.

Winds in High and Low Latitudes. — The polar boun-
daries of the trade- wind lie in a latitude of from 20° to 30° ;
a few degrees nearer the pole we find chiefly south-west
winds in the northern, and north-west winds in the southern
hemisphere. And although these are much more frequent
than any other winds, yet they do not blow so regularly as
the trade-winds. This prevalence of westerly winds in middle
latitudes is proved more particularly by the circumstance
that, according to the average of several years, the packets
from Liverpool to New York are forty days on the passage,
whereas the voyage back again is accomplished in twenty-three
days. If we remove further from the equator, the south-west-
erly winds remain, it is true, still the prevaihng ones, but their
frequency seems to diminish. According to the facts collected
by Dove, Schouw, and myself, all places in high latitudes pre-
sent a preponderance of south-westerly winds, and wherever
particular points exhibit a deviation from this law, we must
seek for the cause in local circumstances. This south-west wind
is nothing more than the descending wind of the upper regions,
which now spreads itself more widely on the surface of the earth.

We find great variableness of the wind in these high lati-
tudes, and it seldom happens that it blows from the same di-

Jtmospherical Phenomena. 25S

rection for sever^ days in succession. When, however, we
examine carefully the directions of the wind, we not unfre-
quently find a tolerably regular order in which they alternate.
Thus, when the north wind blows at a place, after some time
it veers to the north-east, afterwards to the east, and in this
order goes through all points of the compass, until it returns
again to the north. The time occupied by such a circumvolu-
tion amounts to a smaller or greater number of days. Although
the wind often changes suddenly, from one point of the com-
pass to another, and passes through several points in an order
just the opposite of that given above, yet observations made in a
multitude of places go to shew that the first mentioned is the
more usual sequence. Francis Bacon (Lord Verulam) in his
trektise on winds, brought forward this remark of sailors, and
in later times, navigators have often spoken of it in their nar-
ratives without natural philosophers assigning it much im-
portance, until recently Professor Dove has proved the belief
to be founded in fact, by the aid of many arguments and ob-
servations collected from various quarters of the globe ; and
although I do not agree with all the assertions of this acute
and talented natural philosopher, yet I regard the leading fea-
ture of his investigation as perfectly well founded.

Explanation of the variable Winds, — If we examine with
more care the circumstances attending the winds in higher
latitudes, we ought, in our hemisphere, according to the theory,
to find there, as at the equator, a north-east wind, since
the regions lying more to the north are also colder. This
prevailing north-east wind is, however, interfered with by
the already mentioned descending south-west wind, which at
the same time serves, by means of the movement in the upper
strata, in countries lying to the north, to replace the air which
has been moved near the surface towards the equator. Thus
the theory of the trade-winds developed by Halley, requires
in our regions two diametrically opposed winds, which, for the
sake of brevity, we shall designate N£. and SW. Expe-
rience perfectly confirms this, for almost in every part of
Europe of which we possess meteorological observations kept
for several years, the winds from these quarters are the most
frequent ; but, at the same time, we perceive that the south-
west is more frequent than the north-east, wherever there are
no mountains or similar causes to produce a derangement.

254 Professor Kaemtz on the more important

It is these two winds, which, engaged in anveverlasting con-
flict, produce the phenomena of the winds, and with these the
changes in the weather of the temperate zone and of higher la-
titudes. Sometimes the one and sometimes the other prevails ;
and at other times the two form directly opposing currents,
and, at the place where they meet, calms alternate with violent
gusts of wind. Most frequently, however, both advance next
each other with greater or less violence ; and as in the middle
of their course we meet with both winds in greater purity, there
arise, at the place where they proceed next each other, whirl-
winds of great extent, which are the causes of all the other
winds. Without adducing the proofs offered by Dove, it may
be sufficient to offer a short account of the alternation of the
winds. Let us suppose that the NE. has the preponderance *at
the surface, and that it has either completely pressed back the
SW., or driven it to very high regions of the atmosphere ; it thus
continues to extend, and, as it comes from places more to the
north-east, it gradually becomes changed to an east wind. How-
ever, the SW. gradually shews itself in the upper regions, as
we may observe by the course of the higher clouds, while the
vane indicates NE. or E. By the action of the two winds on
each other, the current of air becomes gradually SE. and S.,
until at last it is SW., which direction, owing to the rotation
of the earth, is gradually changed to W. But now, the NE.
gradually recommences, and as both contend at the surface, a
middle direction is produced by the union of the two, which is
moved to N W. and N. as the predominance of the NE. becomes
greater, till at length this last alone blows in the atmosphere.
Thus, in our part of the globe, this circular change is unceas-
ingly going forward, only not with the regularity here supposed,
for it may happen that the NE. has already turned the SW.
to NW. or N. ; but the SW. now acquires new strength from
the equatorial regions, and the wind returns, contrary to rule,
back to the W. and SW.

Moisture of the Atmosphere. — If the relations of wind and tem-
perature which have now been considered are themselves worthy
of close attention, they become much more important by the in-
fluence which they have on the constitution of the sky and the
pressure of the air. The amount of vapour which arises from a
mass of water is a quantity depending on the temperature. The

Atmospherical Phenomena, 255

pressure of the atmosphere, the wind, and other circumstances ex-
ercise, it is true,aninfluenceon therapidity of the evaporation, but
are without effect as to the amount that a space in a state of satu-
ration can take up ata given temperature. This state of saturation
is however but seldom to be found in the atmosphere, and for the
most part the amount of vapour lies between it and perfect
dryness. When we wish to ascertain the amount of moisture
in the air, we must necessarily distinguish two separate quanti-
ties. We must first of all determine the amount of moisture
which the air really contains, whether we deduce the weight of
a cubic foot of watery vapour by simultaneous observation of
the thermometer and hygrometer, or whether, what is always
more suitable, we mark the pressure of the whole atmosphere
by the length of the quicksilver column, in the same way
as this is done for the pressure of the air by the barometer.
The quantity thus found, gives the amount of vapour or the
absolute humidity. Although this quantity forms the founda-
tion of the investigation, yet it is by no means sufficient. For
as the quantity of vapour, which a cubic foot of air contains
when in a state of saturation, is greater at a higher tempera-
ture than when the thermometer stands at a lower point, so the
same quantity of vapour, which, at a low temperature of the
air, characterizes a very moist atmosphere, can, during the
summer, belong to a very dry atmosphere. Hence, in order to
determine this important element, we seek for the amount of
vapour which the air, when saturated, can contain at the mo-
ment of observation, and by it divide the absolute amount of
vapour; the quotient gives by per-centage the relative humidity
or the relative amount of vapour in the air.

As in this manner we obtain the relations of humidity in the
atmosphere under a double point of view, it becomes possible
for us to point out some laws with greater distinctness than was
done by meteorologists in earlier times. When, in the morn-
ing, the sun acts on the surface of the earth, the surfaces of
water thus heated evaporate, and the amount of vapour in the
lower strata of air increases rapidly ; but at the same time the
air becomes heated, and as the pressure of the air off^ers some
opposition to the evaporation, the heat increases much more
quickly than the amount of vapour : the air, therefore, not-
withstanding the accession of moisture, becomes relatively

^56 Professor Kaemtz on the more important

dryer. During the winter months this increase of the absolute
and diminution of the relative humidity continues till about
2 o'clock P.M., and as at that time the heat diminishes and pre-
cipitations ensue on the cold surface, so during the afternoon and
night the amount of vapour is smaller, and the air is relatively
moister, until on the following day a similar course of changes
is repeated. But in summer the phenomena are quite different,
when, during a long-continued east wind, fine weather occurs
with a high temperature. As the surface is then much heated,
the warm masses of air rise with rapidity, and mechanically
carry upwards with them the masses of vapour which they
contain. Although in this manner the evaporation always con-
tinues, yet the absolute amount of vapour resulting from this
ascending stream of air exhibits a maximum about 10 o'clock,
and now it diminishes till the warmest hours of the day in the
afternoon, without ever being so inconsiderable as was the case
at sunrise. We can understand how the dryness of the air in-
creases very rapidly under these circumstances. If during the
decrease of temperature this ascending stream of air becomes
very inconsiderable, the absolute quantity of vapour again in-
creases, owing to the continued evaporation ; and this is the
case more especially at the time of sunset, when the vapours
which have ascended to the upper regions during the day again
sink down ; and now a second maximum occurs, and as during
the night the vapour is precipitated as dew, the amount of va-
pour diminishes till the following morning ; so that we have
during the course of the day two maxima and two minima,
while the relative humidity is pretty regularly changed from
morning till noon, and from that time till the end of the night.
This course, which I have now given as that for summer, is
deduced from observations continued for several years at Halle.
It appears that many differences of climate occur ; but such
observations as would enable us to discuss them minutely are
altogether awanting. Thus the measurements made by Dr
Neuber at Apenrade, on the sea coast, shew a much smaller
diminution of the amount of vapour about the time of noon
than I fpund at Halle, and this is also confirmed by hourly
observations which I made, with the same instruments I em-
ployed at Halle, during the months of July and August 1837,
at Deep near Treptow on the Rega, close to the shore of the

Atmospherical Phenomena. 257

Baltic. The sea breeze, which blows in the morning, and al-
ways brings a moist air from the sea, is undoubtedly the cause
that the course of the absolute humidity should differ here
from what it is in the interior of Germany. We can under-
stand why, under these circumstances, the relative humidity at
the edce of the sea exhibits much less considerable oscillations
in the course of the day than it does at Halle.

I have already mentioned the ascending stream of air by
whose action the amount of vapour at noon is less considerable,
notwithstanding the continued evaporation ; it follows from this,
that in the higher regions, the relations of absolute humidity
must be entirely different from those down below, for the di-
minution must be smaller from 10 o'clock a.m. until 3 p.m., it
must at a certain height disappear, and at length the maximum
of the amount of vapour must take place in the afternoon. A
series of observations which I carried on during the years
1832 and 1833 on the Alps, at the same time that similar ob-
servations were made at Bale, Bern, Geneva, and Zurich, con-
firmed what I have said in a striking degree, and at the same
time afforded a proof of the existence of the ascending current
of air, which, however, would also have been recognised by
means of the motion of the clouds. Thus, while down below, the
course was as I have given it for Halle, on the Rigi, 4000 feet
higher, the amount of vapour in the morning increased much
more rapidly than below, and this continued till noon ; this
was still more the case on the Faulhorn, at a height 6000 feet
above that of the low positions.

If, with the fact above given, we further combine the cir-
cumstance, that the regular changes of the thermometer during
the day are much smaller above than below, it follows, that the
relative humidity above must exhibit an entirely different
course. The most humid and the dryest moments occur, at a
certain height, and also on plains, at sunrise and in the after-
noon ; but the difference between the indications of the hygro-
meter becomes smaller the higher we ascend, as is shewn by my
observations on the Rigi : we must, therefore, reach a point at
which the relative amount of moisture remains almost the same
during the whole day ; and higher up the dryest time occurs
in the morning, and the moistest in the afternoon. This in-
version of the relations observed below, is most satisfactorily

258 Professor Kaemtz on the more important

proved by observations which I continued on the Faulhorn for
twelve weeks, during the two years already mentioned.

From the relations which have now been discussed, a ques-
tion arises, a reply to which would be of the greatest consequence
for a multitude of problems that have hitherto not been dis-
tinctly cleared up : it is the following, — Are the upper strata
of the air, on an average, moister or dryer than the lower ? I
need hardly remark that I do not here speak of the absolute
humidity ; for, as the height of the barometer diminishes with
the increased elevation, so must also the amount of vapour be-
come smaller, — a view which is confirmed by experience ; the
whole investigation turns on the greater or smaller distance of the
air from saturation. Saussure and De Luc, who were the first to
carry hygrometers to the higher regions of the atmosphere, ex-
pressed decidedly the opinion, that the upper strata of air are
much dryer than the lower. In judging of this assertion, we
must not overlook the circumstance, that the observations of
these philosophers were made during excursions in the moun-
tains, for which every one selects the most serene and the dry-
est weather. The only series of comprehensive measurements
was made by Saussure during a residence of several weeks on
the Colde Geant, but unfortunately these observations were ren-
dered less important, because he selected for comparison, only
days when he was not surrounded by clouds, which, by their
moisture, would probably have afibrded compensation for the
dryness of the serene days. Afterwards, Humboldt, in South
America, arrived at the same result ; and as in this case we have
to do with a several years'* residence among the Andes, we must
consider the conclusion as more certain ; but here also we must
not forget, that the lower places lie near the coast, and the higher
in the interior of the Continent; and, since with us the air is much
dryer below than it is there, we may hence, from this cause, ac-
count for the greater dryness in the higher strata of the air.

When we consider that the summits of the mountains are of-
ten surrounded by clouds for weeks together, while the lower
strata of air are far removed from saturation, and since on plains,
during great dryness of the air, we see innumerable clouds pass-
ing over the sky, the opinion does not seem very probable that
the upper regions of the atmosphere are dryer than the lower.
Up to the present time, comprehensive observations, continued

Atmospherical Phenomena, 259

for several years at a high and a low point, are awanting ; for
the measurements made on St Bernard, simultaneously with
those made at Geneva, still leave much to be wished for. If I
were to trust my own experience, the conclusion would be, thai
on an average the upper strata of air are at all events not dryer :
nay, even that they are more humid than the lower. If we
make the comparison in fine weather, then, assuredly, the up-
per regions are generally much dryer than the lower, as has
been found the case by most travellers in the mountains of Eu-
rope ; but when the sky is clouded so that the hygrometer be-
low moves somewhat towards the point of greatest humidity,
then the air above is almost saturated, and, without exception,
the upper regions of air are much moister than the lower. I
must here, however, particularly specify the circumstance, that
this difference in the two conditions of weather is caused, not
so much by the unequal diminution of the absolute amount of
vapour with the height, but much more by an unequal dimi-
nution of heat. When I was on the Faulhorn in the year J 832,
I had several weeks of the finest weather, and the air was much
dryer than at Ziirich ; but in the year 1833, I was almost al-
ways surrounded by clouds, and the air was much moister than
at Ziirich. Notwithstanding this difference, the amount of va-
pour diminished according to the same law in both years ; but
on the other hand, the height to which it was necessary to as-
cend, in order that the thermometer should sink one degree, was,
in the year 1832, double what it was in the following summer.

Although these remarks will doubtless receive many correc-
tions by means of the continued zeal of meteorologists, yet they
seem in some measure to correspond to the condition of the at-
mosphere in our part of the world. I can be shorter in refe-
rence to the cause of these relations in the course of the year.
As the warmth augments in winter, the quantity of vapour also
increases, until it reaches its greatest amount in July or Au-
gust, and then from that time till January it diminishes. The
relative humidity is greatest in December, and from that month,
till May or June the air becomes dryer, when the hygrometer
again moves towards the point of saturation.

Dew, Hoar-frost, Fog, Clouds, and Rain. — When a space
which contains a certain amount of vapour is cooled, it al-

260 Professor Kaemtz on the more important

ways approaches more and more a state of saturation, and
at a sufficiently low temperature a portion of the vapour
is converted into water, and precipitated. It is thus that
there is produced a moist coating on a glass of cold water when
it is brought into a warm moist room : thence may be explained
the moisture on windows during winter, inasmuch as the vapour
is precipitated on the cold glass ; and from the same cause a
mist is formed over a vessel of warm water. What we thus
perceive on a small scale, Nature is constantly performing on a
great. When, for example, the sky is clear and no wind blows,
the ground is cooled rapidly during the night by the radiation
of the heat, and the stratum of air next the ground is some de-
grees colder than the air a few feet above. At last the ground
is so much reduced in temperature, that the strata of air lying
next it are saturated with vapour, and, by a continuance of the
cooling, vapour is precipitated on grass and other objects, in the
form of drops, or in winter in a crystalline condition. The
dew or hoar-frost is so much the more considerable the greater
the cooling, and hence the older natural philosophers ascribed
to dew a cooling power, until at length Wells proved that the
cold is not the effect but the cause of the dew, just as in winter
the windows must be cold before they begin to shew their co-
vering of moisture. Exactly the same phenomenon, which we
perceive, when warm water evaporates in cold air, is presented
to us by Nature in the colder periods of the year, when, for ex-
ample, in autumn, the heat of the air diminishes very rapidly.
From rivers and from smooth sheets of water, which still possess
a high temperature caused by the summer, a quantity of vapours
arise ; the air which is more especially cold in the morning is
saturated in a short time, and the vapours ascending further,
become condensed, and float as water in the form of hollow vesi-
cles (Bldschen) in the air, giving rise to a fog, from whose posi-
tion we can often at a distance trace all the windings of a
river. If this fog becomes denser, several such vesicles unite to-
gether in drops and fall to the ground as fog-rain.

In general, we must suppose, that all clouds arise from the
circumstance, of the air in which they float containing more
vapour than is enough for saturation ; so that we must regard
the clouds as fogs which are continued upwards, and from which

Atmospherical Phenomena. 261

rain, or in colder weather, snow descends, when the super-satu-
ration of the atmosphere becomes still greater. However va-
ried the circumstances may be, relating to the formation of
clouds, yet one law lies at the foundation of the whole of them
which was first announced by Hutton, viz. wherever two nearly
saturated masses of air of unequal temperature become mixed,
either a precipitation takes place, or, at all events, the mixed mass
of air is relatively moister than either of the separate masses.

Between the tropics, where all meteorological phenomena oc-
cur with great regularity, the phenomena connected with rain
are much simpler than in our regions, if local circumstances do
not occasion a disturbance. Where the ascending current of
air acts with power in the region between the two trade-winds,
a great quantity of vapour reaches the upper colder regions of
the atmosphere, which is then rapidly condensed and descends
as rain. This process takes places more especially when the
sun, about the time of its culmination, acts powerfully on the
ground. Hence generally the morning and evening are se-
rene, and the rain falls in the afternoon. As the sun in its yearly
course moves further to the south than to the north, the region
moves with it in which the ascending current of air, and con-
sequently the rain, is greatest ; when the sun removes from a
region, the rain becomes less considerable, and at last fine
weather returns. This alternation occurs so regularly, that
between the tropics, the year has been divided into two halves,
the dry and the wet season.

In our part of the world, where, in the course of the year,
the NE. and the SW. struggle for predominance, the pheno-
mena are more complicated, but still may all be referred to a
few simple laws, if we keep before our eyes the circumstance,
that the SW. is a wind, which, in consequence of its origin,
blows above and then sinks to the ground, while the NE.
spreads itself from below upwards. If, with this, we further
combine the circumstance that the SW. wind, as it comes from
warmer regions, brings along with it moist air from the Atlantic
Ocean, whereas the cold NE. brings dry air from the interior
of the continent, we can easily understand that these two winds
must exercise a very unequal influence on the abundance of the
precipitation?. Observations made for several consecutive years

262 Professor Kaemtz on the more important

at any place on the plains of Germany, always shew that the
SW. and W. are the winds during which it rains most abun-
dantly, while the easterly winds are much more rarely associated
with falls of rain. The changes of the pressure of the air stand
in such intimate connection with the transitions from a serene
sky to a troubled one, and to rain, that the barometer has been
justly named the weatherglass, and it seems to me advisable to
consider both phenomena at the same time.

The Barometer ajidits connection with Temperature. — A short
time after Torricelli's experiments, Guericke and other observers
remarked that the length of the column of mercury in the baro-
meter is in general greater in serene weather, than when there is
wind and bad weather; and thenfoUowed fact after fact, and theo-
ry after theory, until De Luc's theory was received as the correct
one by meteorologists, accordingto which the lighter vapours de-
press the barometer, — a closer examination of all the relations,
however, proved, that in this instance a secondary phenomenon
had been confounded with the principal matter. The changes
of the barometer may be referred to an extremely simple fact,
and although we may not be prepared to account for the oc-
currence of every single phenomenon, yet the cause of this lies
chiefly in the want of simultaneous observations made at remote
places. Originally this instrument only indicates to us the dif-
ference of temperature of districts, which, according to circum-
stances, are more or less remote from one another.

When I spoke of the origin of winds I mentioned the changes
of the barometer. So long as the temperature over the whole
space AB is exactly the same at the surface and at equal heights
above it, the air will remain in a state of equilibrium, and will
press with equal strength on the barometer, but when the space
EF is unusually heated, a portion of the atmosphere lying above
EF descends, and the barometer must necessarily sink, while
it rises at AE and FB.

The reverse would have taken place if the air above EF
had become colder than above AE and FB, for then the
atmosphere would have contracted, and as air would have
rushed into the empty space so produced, the barometer above
E F must necessarily have risen. We also perceive that an
unusual degree of warmth for the season is connected with a
depression of the barometer, and a cooling of the air with a ris-

Atmospherical Phenomena, 263

ing of the barometer. It is easy to be convinced of the truth
of this proposition in the following manner. We observe the
barometer and thermometer at a particular place for some time
at certain hours of each day ; we determine each time, the amount
of change that takes place in each of these instruments, in con-
sequence of the irregular changes of the weather between one
observation and that made at the same hour on the following
day ; further, we distinguish the separate cases in which each of
these instruments rose or fell, and as we are in search of the
changes of temperature corresponding to the variations of the
pressure of the air, we determine how much the heat altered,
when the quicksilver rose or fell 1, 2, 3 ... lines. Observations
in different parts of Europe, in Iceland, on the east coast of
Asia, and near the Equator in South America, have confirmed to
me, not only the proposition announced above, viz. that a dimi-
nution of temperature is combined with a rise, and an increase
with a fall of the barometer, but have also even furnished the
same numerical quantities for the relation between the two
changes. Although the fact is thus proved in a general way,
yet, in reducing daily registers, we find in this point of view
many exceptions from the general rule. If the place lies some-
where between E and F, it happens not unfrequently that the
heat at the surface becomes greater, and that the barometer not
only does not sink, but actually, contrary to the rule, rises. In
considering this anomaly, we must not overlook the circumstance
that the barometer indicates the pressure of the whole atmos-
phere to its extreme boundaries at the point of observation,
whereas the thermometer indicates only the local temperature
of the place where it is suspended to a distance of but a few
feet. But the comparison spoken of above requires, that we
should know the mean temperature of the atmosphere to its up-
per limits ; and although this depends, in a general way, on the
indication afforded by the thermometer at the surface, yet it can
easily happen in particular cases, that the mean temperature of
the whole mass of air may diminish, while it becomes higher at
the surface, and vice versa. If it is difficult to find sufficient
grounds for these anomalies in this cause, the investigation be-
comes still more so, owing to the following fact. I have assumed
that the air is unusually heated above EF, and, in consequence

264 Professor Kaemtz on the more important

of this, a sinking of the barometer is produced by the current
of air to the upper strata. The same must evidently take place
when the air above EF retains the same temperature, while
above AE and FB it is colder, or even when the temperature
above EF sinks a little, but at the same time sinks to a much
greater extent over AE and FB. The want of simultaneous
observations with the two instruments at very remote places,
renders the investigation of such deviations from the general law
more difficult to meteorologists ; but I have, on many occa-
sions, convinced myself of the accuracy of what has now been
stated. For example, the barometer has often sunk very much
in the west of Europe, and the temperature has at the same
time diminished, and in Germany a great cooling was combined
with a slight sinking of the barometer ; whereas in Russia the
air became very cold and the barometer rose exceedingly, so
that it was necessary for us to assume that the air must have
formed a current from the west of Europe.

Although, therefore, the pressure of the atmosphere is con-
nected with the changes of temperature, yet we cannot term it
an ordinary thermometer, but must rather compare it to a dif-
Jhreniidl thermometer. It is well known to my readers, that,
in the latter, two balls are united by a narrow glass-tube, and
filled with dry air ; the air of both balls is separated by a drop
of quicksilver, or some other fluid placed in the tube, which can
move with freedom, and whose position can be read off on a
scale. Whatever temperature the two balls A and B may have,
the position of the drop remains unaltered, so long as the two
are only equally heated ; but if A be more heated than B,
then the drop moves towards B, in consequence of the expan-
sion of the air contained in A ; but this would also have been
the result if the ball A had preserved its former temperature,
while that of B had become lower. Thus, just as here, where
the movement of the drop only indicates that B is become colder
than A, without our being able to say with certainty if A has
acquired a higher, or B a lower temperature than formerly, so
we can only say, that a sinking of the barometer in EF merely
indicates that this part is warmer than AE and FB, which
might arise just as well from an unusual heating of EF, as from
an unusual cooling of AE.

Atmospherical Phenomena. ^QS

Influence of the Direction of the Wind on the Barometer. —
The connection of the pressure of the air with the tempera-
ture is proved by few facts in so remarkable a manner, as by
the influence exercised on the barometer by the direction of the
wind, a fact which has been more particularly placed in a clear
light by L. Von Buch. If we observe the barometer at a place
for some length of time, and ascertain its height during each
separate wind, we find that it is lowest during south-west winds ;
that as we proceed farther from this point, through the west or
east points of the compass, it gradually rises ; and that during
north-east winds it stands, on an average, several lines higher
than during south-west. This contrast of south-west and north-
east winds is pretty general throughout the whole of Europe,
while on the east coast of North America the extremes lie more
in the NW. and SE. The cause of this fact is extremely sim-
ple, for since SW. and NE. are the points from which the
warmest and coldest winds blow, the barometer gives only the
difference of temperature of the two winds.

Dove has added a fact to this investigation, which stands in
intimate connection with his view regarding the shifting of the
wind, and enables us to understand more ^easily the irregular
changes of the weather which are therewith combined. If
we observe the barometer frequently in the morning and
evening, and take the wind which blows between these periods
at about noon ; and if now we apply to each wind a morning
and evening observation separately, we find that the barometer
during SW. and NE. winds alters but little in the course of
the day, whereas during a west wind it rises, and during an
east sinks. Dove has proved this by observations continued
for many years in Paris. Tables of observations on the pres-
sure of the air made almost hourly at Halle, between B'^a.m.
and 10 P.M., for a period of three years, confirm the view in a
remarkable manner. As the barometer has almost the same
mean elevation at 10 a.m. and 10 p.m., it may be sufficient to
indicate the changes in the intermediate period, in which I
shall mark the rise of the barometer by +, and the sinking
by — . In this manner we find

VOL. XXVI. NO. LII.— APttlL 1839. S

siee

Professor Kaemtz on the more important

When the wind h

Change from 10 a.m. to 10 p.m.

Mean Height about Noon.

N.

+ 0.104 L. .

335.426 L.

NE. ..

— 0.097

5.239

E.

— 0.295

4.478

SE. .

— 0.476

3.457

S.

— 0.341

3.137

SW. .

— 0.025

3.291

w. .

+ 0.090

3.875

NW. .

+ 0.562

4.707

Although the continuations of these measurements probably
alter somewhat these quantities, and render less considerable
the still existing anomalies, yet this table shews the opposition
of the south-east and north-east winds, not only in reference to
the mean height of the barometer during different winds, but
also in regard to the changes during the day.

The ground of these phenomena is simple. Supposing that
a north-east wind blows, a low temperature is, for the most part,
combined with it, and thus the barometer is high. But when
the wind veers gradually to the east, the temperature is increas-
ed, and the barometer consequently sinks. Even on the day
when the NE. blows, this depression can be recognised, and
hence the pressure of the air is somewhat less in the evening
than in the morning. As the wind in its further progress to
SE. passes S. and SW., the temperature becomes gradually
higher, the barometer sinks during the whole time, and hence
always stands lower in the evening than in the morning, until
at length during the prevalence of the SW. wind, the air ac-
quires its highest temperature, and the barometer attains its
lowest point, and thus the latter remains during the day pretty
stationary at the same height. But when the wind veers gra-
dually to the west and north, the temperature becomes lower
and lower, and thus the mercury rises ; a fact which may be
observed, not only in the mean height during individual winds,
but also in the change during the day, until at last, during the
NE., the extremes of temperature and of pressure of the air are
reached, when the preceding circle of changes is again renewed.

Almost all changes of the barometer may be explained in the
manner pointed out above, if we regard the instrument as a
differential thermometer. Hence, to adduce one other fact,
the variations of the pressure of the air between the tropics are

Atmospherical Phenomena. 267

inconsiderable, and become greater the more we approach the
poles. For there the temperature alters much less with the la-
titude than here, and violent movements of the atmosphere are
much rarer, owing to the regularity of the trade wind ; hence,
when, at the equator, air comes from a point at 20° Lat., it is
only a few degrees colder, and thus the barometer rises but
little. In our latitudes, on the contrary, air, which comes from
a point 20° to the south, is 10° warmer, or even more, than that
of our climate, and consequently a considerable depression of
the barometer must be the consequence. In winter, when this
difference of temperature of places lying in the same meridian,
but in different latitudes, is much more considerable than in
summer, the movements of the barometer are also much greater
than in the warm season of the year, as has been long known
to natural philosophers.

We have thus seen on the one hand, that the temperature
and pressure of the air, and on the other the cloudiness and se-
renity of the sky, stand in connexion with the direction of the
wind ; and therefore it was an easily pardonable error of the
older natural philosophers, to ascribe the state of the barome-
ter to fine or bad weather. But the barometer is not low du-
ring rainy weather because it rains ; but because the south winds
blow, which are not only moist, but also at the same time warm.
If we had not the Atlantic Ocean to the south-west, but an ex-
tensive sandy desert in its stead, the barometer would under
these circumstances, still sink, but the sky would be clear.

lujiuence of the various Winds on the Weather. — In order
to point out the influence of the various winds mi the
weather, we shall now again go through the points of the
compass. If the sky is serene, and a north-east wind is blow-
ing, the barometer rises ; the wind brings with it, it is true, dry
air, but this is at the same time cold ; and hence if the air was
very moist, the vapours would be precipitated, the sky would
in a short time be covered with clouds, and rain would fall,
and the blue of the sky would appear dark and pure through
the apertures in the clouds. If, on the contrary the air was
not very moist, it would not be saturated notwithstanding the
lowering of the temperature, and the sky would remain clear.
If the north-east wind has blown for some time, the vapours

o P

268 Professor Kaemtz on the more important

are all precipitated as rain, and the sky clears up, especially
when the barometer is slowly descending. The wind gradually
veers to E. and SE., the barometer sinks at the return of the
warm weather, and the sky becomes serene, while it still always
retains its pure colour. If the wind be weak, the sun acts with
power on the ground, and the ascending current of air carries
the vapours rapidly to the upper and cold strata of the atmo-
sphere, especially when the temperature of the day is quickly
rising. A saturation speedily ensues at different points, the
vapours are precipitated, and small rounded clouds {cumuli)
are formed, whose volume and number are increased until noon.
These clouds, a product of the ascending current of air, are con-
stantly driven higher, and consist entirely of fog-vesicles.
After the warmth has reached its maximum, the force of
the ascending current of air diminishes; the clouds sink
lower, and owing to their reaching warmer strata of air, at
length entirely disappear, so that at sunset the sky is quite se-
rene, and remains in this state until the following morning.
When the barometer falls slowly, and when the wind is east,
this succession of changes may be repeated for several days in
the same manner. But gradually the SW. makes its appear-
ance above, separate long-shaped cloudy fibres (cirri) shew
themselves in the sky, and the colour of the latter becomes duller
—at last almost milk-white. These clouds come for the most
part from directions w^hich lie somewhere between S. and W.,
and their height must be very considerable, as is rendered evi-
dent by the circumstance that, even in the middle of summer,
they do not consist of fog-vesicles, but of flakes of snow, for we
find that the rays of light passing through them are as much re-
fracted as they would be by passing through the latter, and
hence give rise to lunar rainbows and mock-suns. Although the
measurements hitherto made are not sufficient to determine the
height of these clouds, which preceded by some hours or days
all the real hail-storms observed by me, yet, during a residence
of nearly a quarter of a year in the vicinity of the Jungfrau
and the FinsteraarJiorn, notwithstanding all the attention I
bestowed, I have never seen a single one of them lower than the
summits of these mountains. When the SW. blows for some
time above, the wind at the surface veers gradually to that
quarter, the barometer sinks, and, as at every moment new

Atmospherical Phenomena. 269

masses of vapour arrive, the clouds become denser, and rain
descends. As the wind veers to the west, while the barometer
at the same time is rising, the rain becomes heavier, the con-
densation into clouds also takes place in the lower strata of the
atmosphere, but the cirri above disappear. If, finally, while
the barometer is rising, the wind veers to the NW. and N.,
although separate showers of rain occur, yet the sky gradually
clears up.

The series of changes we have noticed is that which more
generally takes place, although it does not always occur in the
same regular course that has been mentioned above. As the
wind veers round during its changes, so is it also with the ac-
companying weather, of which one can very easily become con-
vinced, by comparing a sufficiently delicate wind-vane and the
course of the clouds, with the other phenomena of the weather.
I have already mentioned that the moist SW. and the con-
tinental NE. are opposed to each other in regard to the falls of
rain, but the possibility is not thus denied of rainy weather oc-
curring during a NE. and serene weather during a SW. wind.
But the falls of rain that take place during the two winds are
distinguished from each other in a remarkable manner. Widely
extending general rains accompany a SW. wind, and the water
falls slowly and in small drops for days together ; while the NE.
for the most part drives along violent showers of short dura-
tion, which is especially the case when, while the barometer is
high, the wind does not veer regularly from N. through N.E.
to E., but changes suddenly in an irregular manner back to
NW. or W.

It thus appears that the most important phenomena of the
weather may be explained simply by the relations of tempera-
ture ; but, on the other hand, the currents of air and the face
of the heavens have a great influence on the warmth of a dis-
trict, and it is precisely the circumstance of what is the result
of one phenomenon becoming the next moment the cause of the
succeeding one, that accounts for meteorology being so far be-
hind the other departments of physics, owing to the complica-
tion of its phenomena. Inasmuch as we can only observe the
thermometer near the ground, the temperature there may be
very low, although south winds, during a low state of the baro-
meter, impart considerable warmth to the upper strata of the

270 Professor Kaemtz on the more important

air. Such anomalies present themselves more especially in
summer. During that season, the cloudiness of the sky that oc-
curs, obstructs the action of the solar rays on the surface, and
the thermometer frequently indicates temperatures which are
much lower than those occurring during north winds, when
these are accompanied by a serene sky. Although such excep-
tions occur more rarely in winter than in summer, yet they also
present themselves in that season, nay, it can even happen that
such anomalies may be observed for months together. The last
few winters* afford several remarkable examples of this. For
while generally the greatest cold occurs during the greatest
pressure of the air, and the greatest heat when the barometer
is low, the course of the weather was the following during these
mild winters. During south winds the sky was troubled, fine
rain or snow fell, which last, however, was speedily melted on
the surface. The barometer fell slowly, and when it was in a
low state the sky cleared up, piercing cold ensued, but after one
or two days a complete thaw followed, and the dull weather con-
tinued until the wind returned through N. and E. to the south.
Deviations of this kind, by which the character of whole seasons
is often indicated, must be ascribed to the influence of ^he clouds
on the temperature. For since the earth in winter, as it were
consumes what it had acquired from the sun in summer, and
again loses this heat chiefly by radiation, so every thing which
acts on the amount of the latter has a great influence on the tem-
perature. But during the last few winters the south wind blew
more frequently than usual, and a consequence of this was the
predominating warm and moist air. When a north wind arose,
it brought cold air and a precipitation ensued, but after a short
time this covering pf clouds obstructed the radiation, and the
air received back a portion of the heat which had penetrated in
summer into the interior of the crust of the earth. Without
the winds that followed being able to drive back the va-
pours, the south wind in the highest strata of the atmosphere
began by the influence of its warmth to disperse rapidly all the
clouds, and, while the barometer was sinking, so powerful a
radiation of heat took place through the pure air, that the ther-
mometer sank far under the freezing point. But this series of
changes did not last long, for speedily the vapours of the south
* This Essay seems to have been prepared during the year 1835. — Edit.

Attnospherical Phenomena. 271

wind made their appearance, the sky became anew obscured,
the radiation ceased, and while the barometer sank a thaw fol-
lowed.

The most violent movements of the barometer occur during
storms ; and we find a rapid depression during sudden south-
west storms, but a rapid elevation during storms from the north-
east. But although these phenomena may be readily explained
by differences of temperature in different regions, yet it is sel-
dom possible to compare the cause and effect, and in this per-
haps lies the reason, that the view offered above regarding the
connection of temperature and the pressure of the air, was of-
ten brought forward by the older natural philosophers, but al-
ways again renounced ; and that recourse was often had to the
most extraordinary hypotheses. The difficulty of the investi-
gation consisted chiefly in this, — that violent movements of this
kind sometimes occurred simultaneously over a large portion of
the earth ; and that there were seldom the requisite observa-
tions made in remote places. Hence we not unfrequently find,
that the barometer has sunk throughout the whole of Europe
during a temperature which is unusually high for the season of
the year ; but it is only necessary to turn our eyes to other re-
gions (a thing not easily done owing to the reason mentioned
above), and we find a comparatively equally great elevation dur-
ing great cold. Thus there was a very low minimum in one
instance of this kind in Europe ; but in Petersburg, and still
more in Moscow, the mercury was at its mean height. At the
same time, there was a dreadful cold on the east coast of Ame-
rica, probably accompanied by a high state of the barometer ;
observations at Bagdad, shewed great pressure of the air and se-
vere cold, but farthereast,at Calcutta, the barometer was very low.

This fact shews us, not merely that unusual changes of the
weather extend over a large portion of the earth, but also that
the investigation of separate phenomena will be possible, only
when a series of observations from all quarters of the globe can
be made the subject of comparison. In connection with this
gubject, there is also the difficulty of satisfying the wish of the
learned and the unlearned, to predict the state of the weather ;
and I shall now add a few words on this point.

Prognostications of the Weather. — In this problem it is

272 Professor Kaemtz 07i tlie more important

necessary to distinguish two separate cases. For it may
either be required to determine previously, the character
of whole seasons, or to deduce the state of the weather for
some hours or days from the state of the meteorological
instruments. Regarding the first point, owing to the inti-
mate connection existing between all the different parts of
the atmosphere, an approximate solution would only be possible
if we were acquainted with the actual state of the weather over
a large portion of the earth. As this is not the case, the solu-
tion of the problem would be impossible, if the barometer did
not afford us some feeble hints on the subject, by means of its
property of acting as a differential thermometer. When it
stands unusually low, and at the same time exhibits great dis-
turbance, we may thence conclude, that other regions are very
cold, and that we shall not only very soon receive back a por-
tion of the air from them ; but also, that the weather will for
some time follow an unusual course. But more cannot be said
with certainty, as we cannot know at the moment of observa-
tion, whether this great cold has its position in the interior of
Siberia or of America. If the first is the case, then we may
soon expect north-east winds ; whereas west winds come from
America, and these bring us in winter a moist and warm air.
It is thus possible, that the same phenomena may be combined
with perfectly opposite kinds of weather ; but nevertheless,
when we pursue more attentively our observation of the move-
ments of the barometer after that great depression, we are able,
with some degree of probability, to advance somewhat farther.
Thus, when west winds prevail for a long time, the vane veers
gradually to the north and the barometer gradually rises ; but
if the place of the unusually great cold be situated in Siberia,
then usually the N. E. contends suddenly against the S. W.,
the moment of the lowest depression of the barometer is indi-
cated by a violent rain, and the pressure of the air which had
previously diminished with rapidity, again increases just as ra-
pidly during the north-east winds.

i.i It is indeed difficult to predict satisfactorily the character of
whole seasons ; but this difficulty is still further increased, when
we have to indicate, how the weather is to be at an interval of
a few hours ; and in this we must seek for the objection which

Atmospherical Phenomena. 273

is made to the instruments on account of their uncertainty. In
an investigation of this kind we must not merely keep before
our eyes the character of the whole season, but an accurate
knowledge of the whole atmosphere above us is also requisite,
which, from the very nature of things, is perfectly impractica-
ble in reference to temperature and moisture. It is true that
the exertions of travellers have shewn us how these relations
change, as we proceed from the lower to the upper strata of the
atmosphere ; but these investigations relate to the mean state
of the atmosphere, and very important errors are possible when
they are applied to particular cases. We know (to adduce
only one example) that during a certain mean state of the
hygrometer, rain generally takes place ; the barometer sinks at
the same time, and the probability of the precipitation becomes
greater, especially if the sky begins to be obscured by clouds.
But in order to predict with certainty if it will rain or clear up,
a knowledge of the temperature of the upper region is requisite,
and, as this is awanting, there must always be a great degree
of uncertainty in our prognostications. Supposing the tem-
perature at a height of 10,000 feet to be some degrees lower
than usual, a great precipitation would be the consequence ;
whereas, if the temperature should rise an equal number of de-
grees, the sky would clear up with rapidity.

Thus all the meteorological phenomena of our latitudes may
be referred to a constant warfare of the SW. and NE. winds,
and according as the one displaces the other, the weather is
extremely different. But not only is the state of the weather
for single days determined by this predominance, but the cha-
racter of whole seasons depends more or less on the same cause.
A remarkable example of this kind was lately afforded us. In
the summer of 1833, there were very abundant precipitations
throughout the whole of western Europe; the SW. winds pre-
dominated to a great extent, and constantly drove back the east
winds with violence. While in this manner continual cold rains
fell to the ground from the upper strata of the atmosphere, the
warmth of summer was repressed, and thus the month of Au-
gust was distinguished by an extremely low temperature. At
the end of that month movements of the most violent kind oc-
curred in the atmosphere, — storms raged in the West Indies,

274j Professor Kaemtz on Atmospherical Phenomena.

in the Atlantic Ocean, in Germany, and in Nova Zembla ; and
the NE. was violently driven out of Europe. It was not till
December that this latter wind exhibited a tendency to return ;
but during the frightful storms of the 18th and 31st Decem-
ber, the SW. acquired such predominating power, that dur-
ing the next months, the vane hardly indicated an east wind
even for a few hours. The very warm and moist January and
February of 1834 followed, and not only did the SW. inva-
riably bring a warm air, but the cloudiness also interrupted the
radiation, while the winter was extremely cold in North Ame-
rica. But even at the end of February, a north-east wind be-
gan occasionally to blow ; it carried on a conflict with violence
against the SW., more especially during the months of March
and April, and although the victory for a long time remained
undecided, yet the temperature of these months was very much
reduced by the cold polar currents, and this was still more the
case at the beginning of May, when at length the NE. obtained
the mastery. While these east winds brought along with them,
at their first appearance, a great degree of cold, yet the rela-
tions of temperature were speedily altered when the air became
cleared of vapours by their agency ; the sun acted with great
power in the clear sky, and the warm summer of 1834 followed.
It is true that the SW. attempted several times to force it-
self into play, butit found an air which was too dry, and its feeble
power did not bring enough of moisture to saturate the atmo-
sphere ; the latter was troubled for a few hours, but the clouds
were dissipated without any considerable fall of rain. In July,
when it acquired more vigour, the NE. always drove it back,
and violent gales accompanied this encounter, which was con-
tinued from the 20th of July to the end of the month. From
the 21st to the 26th July, the line of this contest passed through
Germany about N. and S. ; but from the last-mentioned day
until the 31st July, the east wind advanced to Ireland, inva-
riably accompanied by storms at the point where the two winds
met. The phenomenon was repeated in the same manner in
August (especially 26th, 28th) and September. Had this pre-
valence of east winds continued longer, we should have had to
expect a winter which probably would have been more severe
than that of 1829-^0; but about the middle of October, vio-

M. Arago on Thunder and Lightning. 275

lent storms began, which continued with but little interruption
till the end of the month, and in this as in several following
contests, the SW. obtained the predominance, in consequence
of which a winter that was not much colder ensued. Thus the
weather from the summer of 1833 till the winter of 1835, was
remarkable for the unusual series of changes which it presented,
according as the one or the other of these two winds blew
more frequently than usual ; but, as I have already observed,
such a fact does not stand in an isolated position, but is inti-
mately connected with the successive states of the weather
over all the other parts of the earth. The summer of 1833
which was so wet in Europe, was distinguished for its unusual
dryness in Asia, viz. in Hindostan, and also in South Ame-
rica; the winter of 1833-4, on account of its extreme cold, was
very unfavourable to the investigations of Captain Back in the
interior of North America. The storm at the end of October
1834, made its appearance not merely in Europe, for unusually
violent commotions in the atmosphere occurred simultaneously
on the whole east coast of America. These are facts which
abundantly prove, that, in changes of the weather, Nature does
not rule in an arbitrary manner, but that also here eternal and
immutable laws exist. — (From Schumacher's " Jahrhuchfur
1838.^)

On Thunder and Lightning. By M. Arago. (Continued
from p. 144.)

Concerning the means by the aid of which it is pretended that
EDIFICES are protected against injury from lightning.

Columella reports that Tarchon imagined that he had com-
pletely screened himself from the injurious attacks of lightning,
by surrounding his dwelling with white vines. Nearly two
thousand years have supplied no additional information con-
cerning white vines, so that we are unacquainted with the

* In the south of Europe, and especially in Italy, when the labourers see
a branch of vine in which the leaves and fruit are completely dried up, they
never fail to ascribe it to the efifects of lightning.

276 Protecting Power of Trees.

grounds on which Tarchon built his hopes.* In the fifteenth
century, a naked sword was Jixed upon the mast head of every
vessel, topi'otect it from lightning. Saint Bernard of Sienna has
recorded the recollection of this custom, and regards it as a mere
prejudice. — (Laboissiere, Acad, du Gard, 18252.) We shall
presently see what must needs be added to the sword, ere it pro-
duce any benefit.

Lightning, casteris paribus, strikes in preference elevated
places ; and from this incontestible fact it has been inferred
that we may conclude that any object is guaranteed by a higher
object placed in its neighbourhood; that a house, for example,
has nothing to fear from the meteor when it is surrounded by
steeples. It has not, however, been sufficiently considered that
specific circumstances, apparent or hidden, may compensate, and
more than compensate, for the influence of superior height. Facts
will here be found to confirm the objection : — On the 15th of
March 1 773, the lightning fell at Naples upon a house occupied
by Lord Tilney, although this house was surrounded on all
sides at the distance of four or jive hundred paces, by the towers
and domes of a great number of churches. It may be added
that these domes and towers were all wet with a heavy rain.
Besides, hundreds of instances might be cited in which labour-
ers were killed by lightning, close by hay-cocks and small
stacks of corn which remained uninjured, though twice or three
times higher than the sufferers.*

Is it true that the trees which overtop a house, at small distances, free
it from all risk of Lightning, as many meteorologists pretend ?

If we have recourse to the testimony of those who purchase vast
extents of forests, for the purpose of clearing them, and converting
the wood into charcoal and timber, it would appear that trees are

* Thunder-stones were formerly considered as a preservative against the
destructive effects of the meteor. All that was required was, at the com-
mencement of the storm, to strike three blows, with one of these stones,
upon each of the fronts of any house ; and, after this, nothing was to he
feared ! We should not have to go far to find this absurd practice in high
esteem, even in our own day. A superstition which is an auxiliary against
fear always lasts long.

Protecting Power of Trees, 277

struck by lightning much more frequently than is generally ima-
gined. When the timber is cut, and converted into planks
or boards, it exhibits a number of clefts and fissures which
have evidently been originally caused by a stroke of lightning.
This observation agrees with a remark which M. De Tristan has
deduced from the watching of sixty-four distinct thunder-storms,
accompanied with hail, which, in the space of twenty-six years,
from 1st January 1811 to 1st January 1837, occasioned great
damage in different parts of the department of Loiret, near the
forest of Orleans. M. De Tristan has noticed that when a
storm passes over a forest it is very decidedly enfeebled.

According to these observations it appears incontestible, that
trees rob thunder clouds of a considerable portion of the fulmi-
nating matter with which they are charged. They are, there-
fore, to be considered as a means of diminishing the power of
the thunder-bolt ; but we go beyond the limits of observation
if we endow them with an absolute protecting virtue. The fol-
lowing facts will shew how decidedly this is true. On the 2d
of September 1816, the lightning fell at Conway, Massachusetts,
on Mr John Williams' house, and did much mischief. And
this in spite of there being in the immediate neighbourhood a
number of Italian poplars of from sixty to seventy feet in height,
whose summits overtopped the roof of the mansion by between
thirty and forty feet. One of the poplars was only six feet from
the spot where the lightning entered the house. Not one of
the trees was struck.

Another proof of the inefficiency of trees as lightning con-
ductors, or as a security for the houses they surround, may be
found in the details of a storm which proved hurtful on the
17th of August 1789, to the mansion of Mr Thomas Leiper,
near Chester, United States. I extract the account from a note
published in 1790 by the celebrated David Rittenhouse. Mr
Leiper's house is built in a steep valley or glen. Towards the
west, the surface at the short distance of sixty yards is at the
level of the highest parts of the house. On this ground there
also exists an alley of large oaks. The storm in question came
from the west ; before attaining a perpendicular position over
the liouse, it had therefore passed the trees, which were
much higher than the roof and chimneys. In this instance they

^8 Supposed Means of preserving Towns,

made no difference ; the trees remained uninjured, and the house
was struck with lightning.*

Of the means hy which it has been alleged that whole towns^ and
even great ranges of country, may he preserved from the in-
jurious effects of lightning.

Ctesias of Cnidus, one of the companions of Xenophon, men-
tions, in a passage preserved by Photius, that he had received
two swords^ the one from the hands of Parisatis, the mother of
Artaxerxes, and the other from the hands of the king himself.
He then adds, " If these are planted in the earth, with their
points upwards, they disperse clouds, hail, and storms. The
king,'''' he continues, " proved this before me to his risk and
periV Has this undoubtedly very curious passage all the im-
portance which has sometimes been conceded to it ? It is now
irrefragably established, I will not say that a short sword, but
that a metallic blade, lance-shaped and pointed, placed upon
the pinnacle of a building, does not disperse clouds. In this
particular, therefore, there is no doubt that the Persians de-
ceived themselves ; to this extent, their opinion is evidently de-
void of proof. This point once conceded, may we not then
suppose that the physician of Artaxerxes only re-echoed a bold
conjecture, which was baseless, when he endowed his sword with
a second property, viz. that of dispersing thunder-storms ? At
all events, and this would not be the first time that truth has suf-
fered by an unfortunate association, are we to be astonished
that the experiment of those two sword-blades was passed
unnoticed, when we find in the very same chapter where it is re-
corded, Ctesias mentions, with the same unhesitating confidence,
the existence of a fountain, sixteen cubits in circumference, and
one orgy'ie deep, which filled every year with liquid gold, add-
ing that they annually draw off a hundred pitchers of this gold ;
at the same time remarking that these vessels should be made

• We may satisfactorily explain this anomaly theoretically, by men-
tioning that the high ground covered with trees is an arid and dry
rock covered with a few inches only of earth ; whilst the house was almost
surrounded with water, and was provided with two lightning conductors,
with all their accessory apparatus, and that many metallic pipes were
placed about the building, reaching from the roofs to the foundation.

Protecting Ejects of Great Fires, 279

of clay, because as the gold, ere long, hardened, it was necessary
to break them before it could be extracted.

Again, in the time of Charlemagne, lo7ig poles were set up
in the fields, to disperse the hail and thunder clouds. We must
instantly add, however, for without this the enthusiastic admirers of
antiquity will find in this passage a manifest proof of the ancient
existence of FrankHn'*s lightning conductors — we must add, that
the poles were quite inefficient till pieces of paper were placed
on their points. Without doubt these papers or parchments
were covered with magical characters, since Charlemagne, in
proscribing their use, by a capitular in the year 789, describes
them as superstitious.

On the effects of great fires burning in the open air.

Certain experiments in natural philosophy, the analysis of
which will afterwards be published, have led to the suppo-
sition that vast fires would conduct to the higher regions
of the atmosphere, the greater part of the fulminating matter
which is borne along by the clouds. These fires would thus
become (such is the opinion of Volta for example) the best
means of preventing thunder-storms, or of rendering them
scarcely formidable. Let us now examine if observation can be
brought to the support of these conjectures. I here lay entirely
aside the absurd idea, that the sacrifices to heaven offered by
the ancients, that all the flames ascending from the altars, and
the black columns of smoke which, from the bodies of the vic-
tims, darkened the air — in short, that all the circumstances, and
all the ceremonies intended, in vulgar apprehension, to disarm
the thundering powers of Jove, constituted simple experiments
in natural philosophy, of which the priests alone possessed the
secret, and which had truly no other object than the enfeebling
and even the gradual and complete destruction of storms.
What I would here present is much less fabulous. I record,
first, a fact which I owe to the kindness of M. Matteucci.
There is a parish, near Cesena in Romagna, of five or six miles
in circumference, over the whole extent of which, in consequence
of the advice of the curate, the peasants placed at intervals
^€)f fifty feet, heaps of straw and brush-wood. On the ap-
proach of a storm, all these heaps of straw, &c. are set

280 Protecting Effects of Great Fires.

on fire. This practice has now been had recourse to for
three years; and during the whole of that time the parish
has not suffered from a thunder-storm, nor has it suffered from
hail, notwithstanding that formerly it used to do so every year,
and within the specified period the neighbouring parishes have
suffered from the meteor in the usual way. It must here be
remarked, that three years do not form a period sufficiently long
to enable us to pronounce definitely concerning the preserving
power of these great fires. I must add, that the experiment is
still in progress, and I shall not fail to give publicity to its re-
suh.

When I alluded, seven years ago, in the ^hge of Volta, to
the ideas of that illustrious philosopher concerning the advan-
tage which might be derived from great flames during thunder-
storms, " I conceived that we might obtain on this point some
information, by comparing the meteorological observations made
in those counties of England, where so many high furnaces
and workshops transformed night and day into great oceans of
fire, with the agricultural ones which surrounded them." This
comparison has been made, and it has been found that the agri-
cultural districts distinctly afford evidence of a larger number
of such storms than the mineral ones ; and yet I do not now
think that the question is by any means settled. The great
furnaces in England abound especially where there are many
metallic mines ; and the rare occurrence of thunder-storms in
these localities may probably with more truth be ascribed to the
nature of the soil than to the action of those enormous fires
which the working of those minerals requires. In the year 1831 ,
I had forgotten one side of the question.

In the experiment which is still going forward near Cesena,
and in that of Cornwall, of which we have just been treating, the
object is to appreciate the simultaneous effect of a great number
of f res. As to a single fire, however considerable it may
be, we can, I beheve, prove that its action is insufficient to
despoil of their fulminating matter even the clouds which are
nearest to it, those in fact which are immediately above it.
Thus, we may instance what took place in the case of Vhotel
Mwitesson at the end of the rue die Mont Blanc, which, on the
1st of July 1810, was occupied by Prince Schwartzenberg. It

Effect produced hy Cannon. S81

was the evening of a Jete given by the Austrian ambassador
to Napoleon and the Empress Marie-Louise. In the middle
of the night an immense ball-room was burned ; and the vast
columns of flame, over which the fire-engines had little con-
trol, did not ward off a tremendous thunder-storm which visited
the immediate neighbourhood. The lightnings followed with
frightful rapidity, and illuminated the whole firmament ; the
thunder rolled without intermission ; finally, torrents of rain
descended, which extinguished the last embers of the fire.

On the noise of cannon as a means of dissipating thunderstorms.

Mariners appear very generally persuaded that the noise of
artillery dissipates thunder-clouds and even clouds of all kinds,
although they cite few authentic facts in support of their opi-
nion. The one most worthy of attention I have found on this
interesting point is dated 1680, in the memoirs of Comte de
Forbin, which were published for the first time in the year
1729 : — '' During our sojourn,"''' says this intrepid mariner,
" upon these coasts (Carthagena on the Spanish Main), there
arose daily, about four p.m., storms attended with lightning,
and which, followed by tremendous thunders, always did some
injury in the town over which they spent their fury. The
Comte d'Estrce, to whom these coasts were not unknown, and
who, in his different voyages to South America, had been more
than once exposed to these kinds of hurricanes, had discovered
tlie secret of dispelling them hy the firing of cannon. He now
tried the efficacy of his remedy against those thunder-storms,
whereupon, the Spaniards perceiving and remarking that after
the second or third discharge of the guns the storm entirely dis-
persed, struck with the prodigy, and not knowing to what to
attribute it, testified great surprise mingled with fear.*"

In several countries the agricultural population, encouraged
by the opinion of naval and military men, have had recourse to
discharges of cannon when they imagined they were threatened
by a thunder-storm, and more especially when it was accompa-
nied with hail. We may first inquire when this practice took
its rise. Without pretending to entire accuracy, I am led to
suppose that it is not of very ancient date. In the first
Encyclopedie^ which was pubHshed in the year 1760, under

VOL. XXVI. NO. LII. APRIL 1839. . T

Effect of Cannon in dissipating

the article Orage^ by M. de Jaucourt, I find the following
statements. " We have heard it more than once stated by
our military men that the noise of cannon dissipates storms, and
that it never hails in besieged towns. '" '"' * " This effect of
cannon is not altogether improbable ; at all events there would
be no harm in making a trial. A few hundred-weight of pow-
der and the expense of carriage of some pieces of artillery, which
would not be a whit the worse, would be all. Perhaps by this
kind of undulatory motion thus excited in the air by the explo-
sion of a number of cannon fired one after another, you might
shake, divide, and dissipate the clouds which were beginning to
ferment."" It evidently appears from the whole of this passage,
that in the year 1765 the use of cannons or of mortars (boites
afeu)^^ as means of dissipating thunder-storms, had not as yet
become prevalent, and that authors still recommended it under
the title of an important experiment. By the year 1769, an-
other step had been taken. For in fact, I find in the eighth
volume of the " Histoire de Fair, et des Meteores^'' that in May
1769, the county De Chamb in Bavaria suffered from violent
storms ; that the fields were thereby ravaged with the exception
of those " where the inhabitants had introduced the practice of
firing a number of small cannon and mortars, so soon as they
heard the thunder commencing.""

It was the same year, 1769, that the Marquis des Chevriers,
a naval officer, who had retired to his property of Vaure-
nard (Mdconna,is) determined to meet the scourge of hail in
the manner he had seen thunder-clouds at sea dispersed, as he
supposed, viz. by the explosion of artillery ; and in this way he
annually consumed two or three hundred- weight of mining pow-
der. The Marquis of Chevriers died about the year 1790, but
the people in his neighbourhood, persuaded of the utility of the
method he had employed, continued it. I find in a memoir
-which was drawn up in the vicinity, by M. Leschevin, chief
commissary for powder and saltpetre, that in the year 1806,
cannon and mortars were in use in the following communes, viz.
Vaurenard, Iger, Aze, Romaneche, Julnat, Torrins, Pouilly^
Fleury^ Saint Sorlin, Viviers^ Boiiteaux, Sfc. The commune
of Fleury employed a niortar whose charge was one pound of

* A sort of cast'iroD mortar fired at rejoicings. Edit.

Thunder-storms. 283

powder ; others employed mortars, larger or smaller, and it was
usually from heights that these explosions were made ; and the
consumption of mining powder, for this purpose alone, was
from nine to twelve hundred-weight a-year.

This process of the Marquis of Chevriers was not confined to
the Mdconnais. Not long ago a mayor in the neighbourhood of
Blois, informed me, that in his commune, they likewise employ-
ed these mortars on the approach of thunder-storms, and he
requested to know if science had conferred its approval upon
the custom ; a query which, by the way, I may remark, seems
to shew that usage had not completely demonstrated its utility.

The Bavarian or Maconnaise mode of dissipating thunder-
storms has been hitherto based upon an opinion of mariners,
and upon the solitary observations made in the seas off the
Spanish main ; but in meteorology the experience of a few days
is a very slender foundation for a general conclusion. In taxing
my memory to try if I could not discover some fact which
might support that one recorded by Forbin, I found one which
was entirely opposed to it, and, which is somewhat remarkable,
it also is derived from an admiral of the time of Louis XIV.,
and founded upon observations made upon the eastern shores of
South America.

Come back then, in thought, to the month of September of
the year 1711, and you may picture the squadron of Duguay-
Trouin before Rio Janeiro. This fleet, composed of the fol-
lowing ships, Le Lys^ Le Mag-nanime, Le Brillant, UAchille^
Le Glorieux, and Le Mars; also V Argonaute^ UAmazone^ La
Bellone and UAigle frigates, and many other vessels of smaller
dimensions, was employed the whole day of the 12th to force
the entrance into the roads, defended by the formidable artillery
of a great number of forts, and also by that of four ships and
three frigates. The interval from the 12th to the 29th was oc-
cupied day and night in an unceasing contest of musketry and
artillery. The galliots threw bombs, the Portuguese set fire
to many mines, blew up many of their ships, burned many,
of their magazines, &c. &c. Finally, on the 20th, the day on
which the place was taken, two of Duguay-Trouin's vessels, Le
Brillant and Le Mars, the battery of the island of Chevres,
consisting of five mortars and eighteen twenty-four pounders,

284 Effect of Cannon in dissipating

kept up a continual fire which overthrew a part of the entrench-
ments of the town ; on the approach of night, upon a signal
given by the commandant, there followed a general firing from
the batteries and vessels, and notwithstanding, all this did not hin-
der the onset of a storm, accompanied, remarks the admiral, with
redoubled claps (rf'fearfid thunder and lightnings zvhich suc-
ceeded each other with scarcely any interval. Here, then, we
have an eocperiment^ in which are, assuredly, to be found all the
favourable conditions possible, and notwithstanding, these many
thousand detonations, infinitely more intense than those of the
small cannon and mortars of the Maconnais, did not prevent
the thunder-storm Jromjormmgi and when it was formed, they
did Qiot disperse it.

If a single fact^ that borrowed from Forbin, has not, as it
would appear, satisfactorily demonstrated that the reports of
artillery have not the power of dissipating thunder-storms, it is
as clear on the other hand, that the isolated fact ^ derived from
the memoirs of Duguay-Trouin, does not prove the opposite
position. It cannot, however, be questioned that those who have
at their command the detailed annals of the late wars, will there
find a multitude of documents more than sufficient to elucidate
the question before us. I shall here repeat two facts which oc-
cur to my own memory, in the hope that they will lead to ana-
logous statements. The 25th of August 1806, being the day
selected for the attack of the islet and fortress of Dannholm,
near Stralsund, General Fririon, that he might harass and fa-
tigue the Swedish garrison, ordered it to be cannonaded du-
ring the whole day. In spite of these powerful and continued
discharges of artillery, a violent thunder-storm visited the spot
at nine o"*clock in the evening. Again, it happened oddly
enough, that the English line-of-battle-ship, the Dul^e^ of 90
guns, was struck with lightning in the year 1793, whilst it was
cannonading one of the batteries of Martinico.

Finally, I may here adduce another observation which, in
default of more direct experiments, may not prove uninteresting.
In the wood of Vincennes, at the distance of nearly two leagues
from the observatory of Paris, there is a polygon fort where the
artillery are in the habit of practising during certain months of
the year. This fort is supplied with eight battering guns

I

Thunder-storms, 9.S5

which fire point-blank, with four others for ricochet firing,
with six mortars, and finally with a moveable battery of six
gun^. The practisings take place upon certain clays of the
week, from seven to ten o^clock in the morning ; and the
number of shots which are fired each day are about 150. As
the reports are still very loud at the observatory, it appears
to me that if they exercise upon the atmosphere that influence
which so many people believe, the sky should be more rarely
overcast on the days of practice than on the other days of the
week ; and this inquiry I have subjected to a minute investiga-
tion.

General Duchan, the commandant of the Vincennes school,
has, at my request, kindly sent me an extract of the days on
which the artillery practised, from the year 1816 to the year
1 835. The total number of these days amounts to 662. Again,
the meteorological registers of the observatory furnish me, for
each of these days of practice, with the state of the sky at nine
o'clock in the morning. Of these ^^9, days, I find 158 during
which the sky at nine a.m. was completely obscured with clouds.
I put, then, the question — If the cannon had notjired^ would the
number have been greater ?

I believe it will be conceded thati put the solution of this
problem upon the fairest possible footing when I take for each
preceding day, and for each succeeding the practice, the data of
the observatory register already alluded to, and then take the
mean of the two numbers as the normal meteorological state of the
practice days. By this method we must be entirely free from
all possible influence of the noise of the artillery. The follow-
ing are the results : —

Of the 662 days before the practising days, 128 were cloudy.

... 662 ... which were practising days, 158

... 662 ... succeeding the practising days, 146

The mean of 128 and 146, viz. 137, is so much a smaller
number than 158, that we might be tempted to conclude that
the noise of the artillery, instead of dissipating and dispelling the
clouds, actually condensed and retained them. But I know well
that the numbers with which we have calculated are too few to
allow us to draw any such conclusion. I shall only, then, af-
*

286 Ringing of Bells during

firm in regard to common clouds, that the discharge of the
greatest guns appears to be wholly without influence.

Another problem, requiring fresh researches, suggests itself;
and I will now take leave to recommend it to the attention of
the superior officers at our artillery schools. Observations upon
the state of the sky in these situations themselves, would be
very valuable. Such as are made at the distance of from two
to five miles, will be objected to by sceptical minds ; and it will
be alleged that such a meteorological station has become exclu-
sively overcast, in consequence of that dispersion which the firing
has effected in the zenith of the guns. It will be indispensable
in this inquiry, to join with the observations of every practising
day, those of the day previous, and the succeeding day, and
the whole three must be taken very accurately, and at the same
time. If the variations of the weather during the time that the
firing lasted, were alone to be taken, we should evidently run the
risk of attributing to the detonations of the artillery, the change
in the appearance of the sky which almost every morning oc-
curs in proportion as the sun rises above the horizon.*

Is it useful or dangerous to ring Great Bells during a Thunder

Storm ?

I proceed to examine this important question without regard-
ing the unhesitating decisions of various learned bodies, whether
executive or judicial,-|- and, at the same time, without any dis-
position to conclude that the widely-spread belief is not based
upon a solid foundation.

* Of the 662 days above referred to, there occur perfectly serene days on
the day before the practice, ... 83

... of 84

after 80

t In the year 1747, the Acad^mie des Sciences itself regarded it danger-
ous to ring the bells, or to cause any other violent commotion in the air,
when the storm was over head. See Hist, de VAcad. 1747, p. 52. A decree
of the French Parliament, under date May 21, 1784, confirmed an ordinance
of the Bailiwick of Langres, wliich expressly forbid the ringing of bells du-
ring a thunder-storm. Two years previously, a similar order had been issued
in the Palatinate, by the Elector Charles Theodore. We might also cite
mandates in virtue of which the same practice was proscribed over the ex-
tent of many dioceses. t,

Thunder-storms. 287

There Is but a single step from the opinion we have just been
discussing, and according to which, the noise of artillery may
break up the clouds, may separate them into small groups,
may, in fact, dissipate them, and rapidly transform the most
threatening and darkest firmament into an azure sky, and the
supposition that the same effects should result from the long-
continued sounding of a great bell. But is it truly by this
chain of ideas that mankind have been led to put the bells in
noisy requisition, with the hope of thus dissipating an expected
storm ? I would the less venture to affirm this, since some anti-
quarian might perhaps discover that the practice of ringing these
church bells is anterior to the invention of powder ; and we shall
be nearer the trujth, I believe, if we look for the origin of this
practice in various superstitious religious considerations.

The bells connected with the Roman Catholic Church are al-
ways consecrated with much pomp when they are hung up.
We shall here give a specimen of the prayers, which, according
to the ritual of Paris, are offered on such occasions. " Grant,
O God ! tliat whenever this bell rings, it may drive far from us
the evil influences of tempting spirits, the dark agency of their
apparitions, the visits of the whirlwind, the strokes of the Ught'
ning, the destruction of thunder, tJte calamities of hurricanes y
and all the wild spirits of the tempest.'''' Again, " May thus, O
our God, be repelled far from us, the wiles of our enemy, the
pelting ofhaily the whirlwind'' s tempest, and the hurricane'' s fury ^
and may all disastrous thunders lose their power r And once
more, " O, Eternal God, grant that the sound of this bell may
put to flight the fire strokes of the enemy of man, the thunder-
holt^ the rapid Jail of stones, as well as all disasters and tem-
pests,''''

This cause, wholly superstitious, which we have just assigned
for the custom of ringing the bells during the time of a thunder-
storm, is not perhaps the only orfe we might assign. I might
also mention a second, scarcely less powerful, by recalling to re-
collection how many individuals have always been compelled to
have recourse to noise, when suffering from fear. The coward
sings in the dark, and when a town becomes a prey to civil war,
the alarm bell is sounded for a much longer time than is ne-
cessary as a mere signal of the event. Savages, also, in all parts

2SS Ringing of Bells during

of the world, utter dGafenlng clamours to terminate an eclipse of
the sun or moon, a phenomenon which strikes them with terror.*
I shall borrow what may be most plausibly said', in point of
fact, concerning the danger which results from ringing the bells
during a thunder storm, from an early volume of the Memoires
de PAcademie des Sciences. During the night between the
14th and 15th of April 1718, in the space comprehended be-
tween Landerneau and St Pol de Leon, in Brittany, the light-
ning fell upon twenty- four churches, and precisely ^ says Fonte-
nelle, upon those where they rang the bells to disperse it. M.
Peslandes, who transmitted the details to the Academy, adds —

* I must here mention that, in thus considering noise tis a kind of panacea,
a singular discovery has been made, which I shall mention here, without
any scruple, in spite of its slight relation to the subject of thunder. If this
discovery is useful, this circumstance will prove an ample apology. Mr
Thomas Gage states, in his Travels, that the American population had re-
course to great noises to disperse a scourge less formidable, indeed, in ap-
pearance than thunder, but, in truth, much more hurtful. About the middle
of the last century. Gage was at Mixco, in the Province of Guatimala, when
a great cloud of locusts invaded the district, and threatened it with com-
plete destruction. Instead of employing against these insects the compli-
cated and unfortunately not at all efficacious means which are sometimes
had recourse to in the South of France, the magistrates encouraged the in-
habitants to use a host of drums, trumpets, horns, &c. The whole popula-
tion, thus armed, advanced against the devastated territory, and made the
air resound with the noise of their multifarious instruments. The noise
caused the locusts to retreat ; and thus were they pursued to the very ocean,
where they found a watery grave.

This method of driving away locusts is also used in "Wallachia, Moldavia,
and Transylvania. (See Phil. Trans, for 1749.) It is not many years since
myriads of these insects having appeared in Bessarabia, the Military Gover-
nor of the province put a great number of the peasantry and soldiery in re-
quisition ; he supplied them with a number of copper vessels, with drums,
trumpets, speaking trumpets, &c. and set tliem forth in pursuit of the
devastating insects. The Governor entertained the odd fancy of conferring
the command of the expedition i|{)on the celebrated Russian poet and
fabulist, Pouschkin, who was then an exile at Kicheneff ; the poet, however,
declined the honour ; he would willingly have put words in the insects
mouths, but would not kill them. These effects of a tremendous noise upon
locusts, if well established, would be infinitely more valuable than that re-
corded by the historians of the Crusades, where they mention, that at the
siege of Acre, the army of the Francs brought down by their shouts the car-
rier pigeons, which, according to the Eastern custom, earned information to
\\ie besieged Mussulmen.

Thunder-storms. 289

the neighbouring churches, where they did not ring, were spared.
This observation has been reported in much too laconic a style ;
for it often happens that thunder-storms have a long and nar*
row course over a district, and it might have been so in Brit-
tany. Again, with regard to the churches which were saved,
were they not out of the direction pursued by the stormy
clouds ? In those belfries where they were ringing, the deaths
and severe wounds which occurred among the ringers, clearly
demonstrated the fall of the meteor; in other places, all the
damage, consisting merely of slight fissures in the wall, or the
fall of a little plaster, might be passed by without being noticed.
Finally, we ought, above all, to have been informed what were
the comparative heights of those steeples which were struck, and
of those that were unscathed. With all these uncertainties, the
observation of M. Ueslandes does not possess, it must be con-
ceded, the character of a true demonstration ; and science can
designate only as a simple probability, the conclusion which has
been drawn.*

An argument against the ringing of the bells during a thun-
der-storm was much insisted upon in the month of August 1769,
from the circumstance that lightning fell upon the steeple of
Passy during the very time they were continuing to ring; but,
all things considered, it will be found that, throughout the long
continuance of the storm, they rang with no less assiduity at
Auteuil and at Chaillot, and, notwithstanding, the steeples of
these two communes, between which the struck belfry of Passy
stood, received no injury.t

* Tlie numerous and severe disasters of the 15tli of April 1718, did not
at all injure the reputation of the bells in the estimation of the people in
Lower Brittany. The 15th of April 1718 was Good-Friday, a day on which
no bells should soimd. Hence they contended there was no ground of as-
tonishment, if those tvho, against a precept of their church, rang them,
should be punished fo r their crime.

t In the year 1781, Khh6 Needham of Brussels conceived that he had
proved, by a cabinet (jxperiraent, that the ringing of bells is wholly inope-
rative, and does neither good nor harm. The detailed discussion of this
experiment will naturally occur at a future time, when I shall examine all
the analogies of lighti ling and of electricity. On the present occasion, I shall
only add a few words by anticipation, that the reader may at least perceive
the problem in all its aspects.

290 Ringing of Bells durmg Thunder.

In conclusion, we remark, that in the present state of the
science, it is not proved that the ringing of bells renders strokes
of lightning more imminently dangerous; — it is not proved that
any great noise has ever made the lightning descend upon
buildings, which would not, independently, have been struck by
it. But, notwithstanding this, it ought raost^decidedly to be re-
commended that the bells should not be rung, for the sake of
the ringers. The danger which they run is similar to that
which those imprudent individuals expose themselves to, who,
during a thunder-storm, take refuge under a tree. Lightning
strikes elevated objects, and especially the spires of steeples ; the
hempen cord attached to the bell, and commonly imbued with
moisture, conducts the discharge to the very hands of the ring-
er, and hence so many deplorable accidents.* It should be re-

M. Needham constructed a model steeple in wood, three feet high, in
which he suspended a bell five and a half inches in diameter, and so ar-
ranged, that it might be rung by means of a handle. At the top of the
steeple was placed a metallic ball, whose communication with the earth, or,
in the language of the natural philosophy of the day, with the common re-
servoir, was properly established. This ball was placed opposite a precisely
simila^ ball, belonging to the conductor of an electric battery, which was
charged to saturation. When the bell was not ringing, the explosive dis-
tance— the distance to which the spark darted, from the ball of the conduc-
tor to the ball of the steeple — was a quarter of an inch. The two balls were
then placed at the distance o/Aa?/ an inch, when it was foimd that no spark
was emitted, and there was no flow of the electric fluid between them, al-
though the bell was rung strongly and rapidly, I look upon this experiment,
says the Abbd, as decisive. All, however, will probably not be of this mind.

M. Needham having successively made the experinrient when the two balls
were at the distance of a quarter, and of half an inch from each other, would
have been perfectly right in concluding, from these results, that the sounds
of the bells did not considerably augment the facilit}' of the electrical dis-
charge, and that it did not double the explosive distance. But before he was
authorized to affirm that the noise had absolutely no effect, I think he
should have passed from the distance of a quarter to half an inch, not all at
once, but by insensible degrees. Moreover, the small electrified masses —
the two copper balls approximated to each other by M . Needham, were both
soUd bodies. In the atmosphere, on the contrary, we see floating clouds
which the vibrations of the air may so far modify in t heir form, as sensibly
to affect the electric tension of the surface which i s turned towards the
earth. The Abbe's experiment would have been very valuable had it
given a positive result; but yielding only a negative <dne, it appears to me
almost valueless in a meteorological point of view.

• To the unfortunate incidents already enumerated I (p. 119), I shall now

Dr Daubeny on Volcanos. 291

marked, that if the rope, whether wet or dry, does not touch
the ground, which is generally the case, the fulminating matter,
after it has reached the knot at its lower end, may, to a great
extent, reascend it, may again reach the summit of the steeple,
and then be dissipated in space. When this is considered, it
will be seen, that we are not to conclude that because no da-
mage has been done in the interior of a belfry, therefore the
ringers would not have been killed.

Reply to Professor BiscJiofs Objections to the Chemical Theory
of Volcanos. By Charles Daubeny, M. D., F. R. S.,
Professor of Chemistry and of Botany, Oxford. (Com-
municated by the Author.)

Having already stated in a former Number* of your Journal,
as well as in other publications,-[- the grounds on which I have
long considered Davy's Theory, with such modifications as I
have myself ventured to introduce in it, as affording the best,
if not the only adequate explanation of the phenomena present-
ed, during the different phases of volcanic action, I feel some
reluctance in trespassing upon your pages by any further dis-
cussion of what may appear to you a trite and hackneyed sub-
ject. Nevertheless, on rising from the perusal of the last Num-
ber of your periodical, I could not but feel, that when a che-
mist so distinguished for his researches in this class of pheno-
mena as Professor Bischof of Bonn, professes to lay down as
the result of his inquiries into the " Natural History of Vol-
canos and Earthquakes,^' that the hypothesis in question is un-
tenable, it behoves me, either by abandoning my preconceived
views, to acknowledge the justice of his arguments, or to take

add another, as these facts are tlie best means of curing the ringers of their
hazardous folly. On the 31st of March 1768, the lightning having descended
upon the steeple of Chabeuil, near Valence in Dauphiny, killed two young
men who were engaged in pulling the rope together, and severely wounded
nine others w^ho were standing near them.

* No. for October 1832.

t Encyclp. Metrop. article, Volcanic Geology.

292 Dr Daubeny on the

an early opportunity of pointing out wherein I conceive them
to be erroneous.

It is true, that the gulf which a difference of country and
language, even under the favourable circumstances of the pre-
sent day, interposes between the productions of English and
foreign literati, has prevented the Professor from noticing the
views of so humble a fellow labourer in the field of science as
myself,* and hence, fhat he has done little more on this subject,
than reiterate objections which had been previously advanced,
and, as I had hoped, had been long ago set at rest by myself.

I trust, therefore, that your readers in general, now that the
subject of volcanos has been so prominently brought before
them by the publication of Bischofs various memoirs, will not
grudge me the small additional space requisite for supplying
these omissions, and that the Professor himself, who has taken
so much pains to bring together every thing that can be sup-
posed to bear, however remotely, upon the questions at issue,
will be obliged to me for thus directing his attention to publi-
cations, which do not appear yet to have met his eye.

I proceed, then, to notice in detail the several objections al-
ledged by Bischof to the chemical theory of volcanos, first,
by stating their substance briefly, though I hope with fairness,
and afterwards subjoining (in many cases in the very words of
my former publications) the grounds on which I consider them
inconclusive.

1^^ Objection. — It is not true that volcanos are always near
the sea.

Pesckan, in the centre of Asia, is 260 geographical miles from
any great sea, and yet has given rise to streams of lava within the
period of our history. It also lies 25 geographical miles from
the lake of Timartu or Issikul, which is not twice as large as
the lake of Geneva.

The volcano of Turfan also is surrounded by very incon-
siderable lakes.

Ans7ver. — The general connection of volcanic action with,
or a proximity to, large masses of salt or fresh water, is all that
seems required by the conditions of our theory.

* He alludes once or twice to ray work on Volcanos, but not with refer-
ence to any points of theory.

Cheviical Theory of Volcanos. 293

Now, in proof of this general proximity, it may be re-
marked, that out of a catalogue of no less than 163 active
vents enumerated by M. Arago, as occurring in various parts
of the known world, all, excepting two or three in different
parts of America, and about the same number of which we
possess very imperfect information, in Central Asia, are within
a short distance at least of the ocean. It is even found that
the very excepted cases, when examined, tend to confirm the
rule, being so situated, that their connection, either with the
ocean or with inland seas that may supply its place, becomes
a matter of fair inference. In proof of this, we need only re-
fer to the descriptions given by Humboldt of JoruUo ; from
which it appears, that distant as this mountain may be both
from the Atlantic and Pacific Oceans, it is nevertheless con-
nected with one or both through the medium of a chain of
volcanic eminences ; and even the volcanos of Tartary, whose
existence in an active condition is more problematical, may be
connected with some of these extensive salt lakes which seem
to abound in the depressed portion of Central Asia.

2d Objection. — Atmospheric air cannot gain admittance to the
focus of a volcano, because there must be an enormous force
acting outwards to protrude the liquid lava to so great a height,
and as this pressure continues for many years, during which
time the phenomena by no means abate in activity, it is im-
possible that air should in any way contribute to it.

Answer. — The very conditions of our theory imply the exist-
ence near and about the focus of the volcano of vast caverns,
caused, originally by the heaving up of the softened rocks,
owing to the elastic vapours disengaged, and consequently
filled in the first instance by these matters. But the amount of
these vapours must be undergoing continual oscillation. \sty
Owing to differences of temperature caused by the constantly
varying intensity of the volcanic action. 9.dly, By the reaction
of the gases upon each other, as for instance, sulphuretted hy-
drogen upon sulphurous acid, muriatic and carbonic acids upon
ammonia, the fixed alkalies and the earths. 3(%, By the ever-
varying proportion between the amount of water decomposed
by the alkaline or earthy metals, and generated by the union of
hydrogen to the oxygen present. Hence, unless the passages

294 Dr Daiibeny oji the

between these caverns and the external atmosphere were her-
metically sealed (which no one contends), air must at times en-
ter the latter to fill the vacuum thus occasioned. ♦

2d Objection. — If the oxidation of the earthy and alkaline
metals were to take place at the expense of water, enormous
quantities of hydrogen would be evolved, which has never
been observed.

Answer. — Hydrogen could hardly be expected to escape in
a free state from a spot which contained so many elements for
which it possesses a strong affinity, and to which it would be
presented under the influence of the pressure and temperature
so well calculated to promote its combination with them.

Thus, sulphur and chlorine we know to be generally pre-
sent in volcanos, and oxygen and nitrogen, we may fairly as-
sume to be so. But, although hydrogen may not be disengaged
alone, large quantities of it in combination with sulphur appear
to be almost universally evolved from volcanos, and it is proba-
ble that the great beds of sulphur which exist in most volcanic
districts (viz. Sicily) are the result of the decomposition of the
sulphuretted hydrogen evolved. Nor, indeed, does it seem pos-
sible to explain the presence of this hydrogen, without having
recourse to the chemical theory.

4^/i Objection. — The evolution of carbonic acid by volcanos
is not explained, and these disengagements of carbonic acid
gas could not take place in the presence of atmospheric air in
those vast subterranean cavities without their mixing together.
Now, the carbonic acid evolved by volcanos (Vesuvius, Eifel,
&c.), contains but little atmospheric air.

Answer. — The evolution of carbonic acid in countries ex-
posed to the influence of volcanic heat, would seem to be a ne-
cessary result of the existence of calcareous matter in the rock
formations. Its continuance for so long a period after the vol-
cano has ceased to be in activity, seems to shew, that it is not de-
rived directly from the chemical processes which produce the
phenomena in question, but is only caused by the heat which
these processes tend to diffuse through the adjacent rocks. Hence
there seems no reason why it should be intermixed with any
large proportion of common air, though, as I have shewn, this

Chemical Theory of Volcanos. 295

ingredient is rarely altogether absent in any samples which it
has fallen to my lot to examine.

5th Objection. — No nitrogen, according to Boussingault, is
evolved from the volcanos under the equator, as would be the
case if any process of oxydation were going on in which atmo-
spheric air co-operated.

Ansiver, — The nitrogen remaining after the atmospheric air
had been robbed of its oxygen, by the inflammable bodies pre-
sent, may reach the air either in a separate condition, or united
with hydrogen in the form of ammonia. The former I have
generally found to be the case in thermal springs connected
with volcanos in an extinct or languid condition — the latter in
the craters or fumaroles of those still in a state of greater or
less activity. I do not wonder therefore, that Boussingault
should have rarely detected nitrogen in the volcanos of the
equator,* but I should expect that sal-ammonia may, never-
theless, be exhaled from some of them. If this be not the case,
it is still possible that the sal-ammoniac sublimed may have
been accumulated within some of the vast cavities existing in
the interior of the volcano, so that the occasional absence of
nitrogen seems less difficult of explanation in accordance with
the chemical theory, than the frequent association of it with
volcanos is, if we do not have recourse to this hypothesis.

Gth Objection. — The metals of the earths are not sufficiently
ox4dizable to kindle on the access of water, and to produce the
intense heat which would be necessary for producing and lique-
fying lavas.

^n5re?er.|r-Silicon, though when pure it is incapable of de-
com|X)sing water, and is incombustible in oxygen, yet kindles
readily, when united either with a little hydrogen or with alka-
line carbonates. Aluminium even by itself burns brilliantly
when heated above redness, and dissolves with the evolution of
hydrogen in very dilute solutions of potass.

Calcium and magnesium appear to be still more inflamma-
ble, and the bases of the alkalies, present along, and perhaps
in combination with them, might, whenever water obtained ac-

* In two instances it was present.

296 Dr Daubeny on the

cess, generate heat sufficient to cause the other bases to enter
into combination with oxygen. Besides, we know that alumi-
nium and magnesium enter readily, with an evolution of heat
and light, into combination with chlorine, a body which (as
we shall see) there is good reason for supposing present in
volcanos.

^ith Objection. — The slight specific gravity of the metals of
the alkalies proves fatal to Davy's hypothesis, for, if the mean
density of the earth surpass that of all kinds of rocks, these
metals cannot exist, at least not in great quantities, in the in-
terior of the earth.

In reply to this I cannot do better than extract the remarks
which I made in reply to the self same objection in my article
on volcanos, published in the Encyclopaedia Metropolitana in
the year 1833.

" An objection against our hypothesis, has also been sometimes de-
duced from the mean density of the Earth, which is calculated at five
times that of water ; and hence it has been concluded, that bodies so
light as potassium and sodium are, cannot make a part of its nucleus.

But we are not obliged to imagine a larger proportion of these alka-
line bases to be present, than would be implied by the composition of the
lava emitted, and probably we shall find not more than four or five per
cent, of potass or soda to exist, in the average of volcanic productions.

On the other hand, the specific gravity of the basis of silica, and pro-
bably, also, of that of the other earths which predominate in lava, is SFuf-
ficiently considerable to warrant the conclusion, that a mass of matter,
containing these principles in the proportions indicated, and united With
as much metallic iron as we know to exist in the state of an oxide in
the generality of lavas, would form an aggregate possessing a higher spe-
cific gravity, than that of the compound resulting from the oxidation of
the entire mass.

Let us take for instance, the analysis given by Dr Kennedy, of the lava
from Etna, which he states to consist of

Silica, 52 per cent X Sp. gr. 2.66 = 127.8

Alumina, 19 per cent X Sp. gr. 4.20 =: 79.8

Lime, 10 per cent X Sp. gr. 3.00 =: 30.0

Oxide of Iron, 16 per cent X Sp. gr. 6.00 =: 75.0
Soda, 4 per cent X Sp. gr. 2.00 = 8.0

100 320.6

We here find, that 100 parts of this lava have a specific gravity equal
to 320.6, and consequently that the specific gravity of the mass would be
no more than 3.2, supposing it divested of water.

Chemical Theory of Volcanos, 297

Now, let us contrast this -with the specific gravity of 100 parts of the
metallic principles, which would give rise to a mineral possessing the
above chemical composition.

Silica, 62, contains of base, 26 x sp. gr. 2.0 = 62.0

Alumina, 19, contains of base, 10 X sp. gr. 2.0 = 20.0

Lime, 10, contains of base, 7 X sp. gr, 4.0 = 28.0

Oxide of Iron, 15, contains of base, 12 X sp. gr. 7.8 = 93.6
Soda, 4, contains of base, 3 X sp. gr. 1.0 = 3.0

100 68 196.6

Now as 58—196—100—340.
Consequently the specific gravity of the whole would be no less than
3.4. The specific gravity of aluminium appears not to be ascertained,
but probably it is not inferior to that of silicon, which sinks in the strong-
est sulphuric acid, and therefore is more than 1.83.

The theory, therefore, we have been advocating, leaves the question, with
respect to thecause of the Earth's density, just on the samefooting as before.
Those who are of opinion, that the latter may be explained by the mere
condensation of such rocks as are found near the surface, in consequence
of the superincumbent weight, as certain metals may be rendered heavier
by pressure, are entitled to extend this explanation to the case of the al-
kaline and earthy bases ; whilst those who regard the density of the
Earth to be a proof that some heavier matter must exist below, are not
precluded from such a supposition, as our theory implies merely the ex-
istence of such a quantity of metallic ingredients, as would be sufficient
to produce the materials ejected, leaving the constitution of the remain-
der just as open to conjecture as it was before.

It is curious indeed, that rvhilst some have argued, that the kind of
materials found near the surf, -e is inadequate to account for the density
attributed to the Earth in general ; others, as the late distinguished Pro-
fessor Leslie, have contended, that these substances would have their
specific gravitj'^ so much increased by the enormous pressure from above,
that void internal spaces must be necessarily supposed. On this he has
founded his singular h}^othesis, that the centre of the Earth is filled only
with light, the rarest substance known j an idea, the mere mention of
which is sufiicient to shew how little we can be justified in rejecting an
explanation of facts, merely because it appears to militate against the
conjectures that may be conjured up with regard to the internal condi-
tion of our planet."

Sth Objection, If, according to Gay-Lussac, the hydrogen of
the decomposed water goes to form muriatic acid with chlorine,
the above mentioned acid ou<jht to be general in volcanos.
Now, it is wanting, according to Boussingault, in the volcanos

VOL. XXVI. NO. Lll. APRIL 1839. U

298 Dr Daubeny on Volcanos,

under the equator in the New World, and according to Bis-
chof, in those near the Rhine.

Answer, I believe, that muriatic acid will be found pretty
constantly present in volcanos now in activity. Sir H. Davy
found it at Vesuvius on both the occasions he visited that vol-
cano, viz. 1815 and 1829. I myself in 1834, detected it there
in great abundance; and in 1825, found it at the Solfatara,
in the Island of Vulcano, and near Mount Etna. It has been
discovered also in the volcanos of Iceland ; in those of Java,
at Mount Idienne ; and of South America, at Purace. The
sal-ammoniac which so abounds in the volcanos of Tartary,
shews, that it is also present there ; and the existence of it in
the trachytic rock of the Puy de Sarcouy in Auvergne, proves,
that it was a concomitant of volcanic action in days that have
gone by.

All therefore that Bischof is warranted in inferring from its
absence in the case of the volcanos of the Rhine and Equato-
rial America, is, that it ceases to be disengaged when the ac-
tion becomes languid or extinct. Now there are many ways of
accounting for this. In the first place, granting the acid to be
derived from the sea-salt present in the water which originated
the volcanic action, it would cease to be generated when this
fluid no longer obtained admission ; or, when the heat was in-
adequate to cause the union of the alkali of the sea-salt with
the earths present ; and even if it were still generated, it might
be prevented from rising to the mouth of the crater, by com-
bining in its way with the calcareous rocks through which it
had to pass. Hence the carbonic acid, which Professor Bis-
chof remarks as so abundantly evolved by the volcanos of the
Rhine, may perhaps represent an equal volume of muriatic
acid, by whose agency it had been evolved from the limestones
that contained it.

Thus have I replied seriatim to all the objections, which an
acute and learned opponent has been able to adduce against
the chemical theory of volcanos ; and having done so, might be
expected perhaps to proceed to some remarks on the one to
which he himself has given the preference.

But in order not to occupy too much of your space, I will
jnerely here remark, that Professor Bischof appears (at least in

\

Radiaticyn of Rough and Polished Surfaces. 299

the portion of his memoir yet published) to pass over without
any attempt at explanation, certain chemical phenomena of
constant occurrence, which follow directly from the principles
of the theory to which he has objected.

These are, 1*^, The evolution of sulphuretted hydrogen, in
quantities far exceeding what are to be explained by the reac-
tion of carbonaceous matter upon sulphates, or any of those
other processes which sometimes produce it on the surface of
the earth.

9.dly^ The disengagement of sal-ammoniac, for although one
of the constituents of this compound, the muriatic acid, might
arise from the decomposition of sea-salt by aqueous vapour, the
other one, the ammonia, implies the presence of free hydrogen
as well as of nitrogen gas, near the focus of the volcanic action.

3J/z/, The circumstance, which I have substantiated in so
many cases, that I begin to believe it almost universally true,
that the atmospheric air exhaled from volcanos, and indeed
generally from the interior of the earth, is deprived in a greater
or less degree of its proper proportion of oxygen. That pro-
cesses, therefore, by which this principle is abstracted, are going
on extensively within the globe cannot be denied, and hence I
conceive that any theory, which attempts to account for vol-
canic action, witliout taking notice of so essential a phenome-
non, ought to be regarded as imperfect, and unsatisfactory.

Upon the alleged Injluence which the Roughness and the Polish
of Surfaces exercise upon the Emissive Power of Bodies, in
reference to the Experiments of Professor Sir John Leslie.
By M. Melloni.

When we measure the intensity of calorific radiation which
takes place from the two sides of a metal vessel filled with boil-
ing water, having the one of its longitudinal sides highly po-
lished and brilliant, and the other, though at first polished, yet
subsequently more or less streaked or furrowed with emery, or
with the graver, or the file, we discover that the quantity
of heat emitted by the streaked or unpolished surface, is always
superior to that which emanates from the brilliant one. These
u2

500 Radiation ofRoufrh and Polished Surfaces.

variations sometimes exceed the ratio of two to one. Hence
a deduction has been drawn, that the observed increase is owing
to those inequalities which have been impressed upon the vessel,
and that, consequently, the superficial asperities of bodies have
the property of facilitating the exit of the heat which they con-
tain. I beg the honour of communicating to the Academy the
abstract of a series of researches, whence it seems decidedly to
follow that this proposition is wholly erroneous ; so that if the
superficial layers clearly and decidedly contribute to make a
difference in the quantity of heat emitted by a hot body, the
state of the surface has no part in the production of this phe-
nomenon.

First, I must avow that, in spite of the authority of great
names, the influence of this polish in calorific emission, has al-
ways appeared to me very doubtful. It is said, the interior
heat experiences in quitting the body the same action of the
surface which it undergoes in penetrating it in the way of ra-
diation. Be ^it so. But why should these small shining j^-
cettes (facettes miroitantes ) which you produce by streaking
the polished plate, reflect interiorly less heat than the surface
uniformly polished? Take a vessel of copper, having two po-
lished sides slightly obscured by exposure to the air : make
with the graver on the one of these sides, a series of parallel
furrows ; the little furrows thus produced, will certainly be more
brilliant then the rest of the vessel, and, notwithstanding, the
furrowed surface will emit more heat than the smooth one. It
IS now nearly two years since I imparted this objection and
some other experiments of the same sort, to Messrs Bache,
Henry, and Locke, distinguished professors of physics from
the United States, who were then in Paris. Now, however, that
the question appears to me decided, I lay aside all indirect ob-
jections, and pass immediately to the exposition of results which
conduce directly to the proof of the alleged fact.

I took a cubic vessel of copper, whose four faces were very
carefully formed ; externally, I soldered on its lower angles and
edges, grooves provided with springs, for the purpose of sup-
porting firmly against the vessel plates of two or three lines in
thickness ; and having afterwards procured two pairs of plates,
one pair of jet, and the other of ivory, I applied them to the

Radiation of Rough and Pollstied Surfaces, 301

four sides. Each pair was composed of plates in every respect
alike, except as it regarded the external surface, one of which
was very smooth and brilliant, and the other was not polished,
and was streaked with emery. On precisely measuring with the
thermo-multiplier, the quantities of heat projected by the two
polished faces, when the vessel was filled with hot water, and in
comparing them with those which emanated from the corres-
ponding streaked faces, I could only perceive differences to the
extent of one or two hundredths (centiemes), and these some-
times on the one side and sometimes on the other. The mean
of twenty observations yielded only a variation which scarcely
amounted to a few thousandths fmilliemesj, and, ccfisequently^
might be altogether disregarded.

To this experiment it may perhaps be objected, that in
spite of the precautions taken for the establishment of a perfect
contact betwixt the plates and the vessel, we have nevertheless
no certainty that the two plates which composed each of the
pairs submitted to experiment, possessed the same tempera-
ture. To avoid this objection, I caused a square reservoir to
be hollowed out of a small block of marble, the sides of which
were reduced to a perfectly equal thickness, and the external
surfaces of which were differently prepared. The first was
smooth and brilliant ; the second was equatty smooth, but un-
polished and tarnished ; the third was streaked in one direction ;
and the fourth in two, crossed at right angles. The vessel was
then filled with hot water, and projected the same quantity of'
radiating caloric from each of the four sides.

Hence, it appeared that the more or less irregular state of
the surface has no influence upon the emissive power, when the
radiating body is not of a metallic nature.

I then covered with lamp-black one of the faces of my marble
vase, as well as one of each of the pairs of plates I had employ-
ed in the preceding experiment. As it has been agreed to re-
present by the number 100, the emissive power of lamp-black,
I could easily determine, by successive comparisons, the pro-
portional numbers which represented the emissive powers of
ivory, jet, and marble. The whole three were found to be com-
prised between the numbers 93 and 98. But here might it not
be said, that if in the substances which were thus employed, the

302 Radiation of Rough and Polished Surfaces,

influence of the unpolishing is nothing, this is owing to their
emissive power reaching the limit of maximum, beyond which
an augmentation can scarcely occur, because the emissive sur-
face no longer supplies a hindrance to the escape of the heat ;
whilst in metals, far removed from this limit, the alteration of
the state of the surface must necessarily exercise all its influence,
and render it sensible by a marked variation in the quantity of
caloric emitted ?

Although this reasoning is based upon a pure hypothesis,
viz. that lamp-black opposes no resistance to the radiation
from the surface ; and although the emissive powers of the
three substa\ices employed are indeed, on the one hand, so far
removed from the number 100, as to permit us to appreciate
the variations produced, and yet, on the other, are so energetic
that the smallest proportion of change occurring in their values,
would make them overcome the whole distance which separates
them from this number ; notwithstanding, let us for a moment
abandon all these non-metallic substances, and endeavour to
determine the question from the bodies themselves with which
we are now more especially concerned.

Copper, zinc, tin, and white iron, which, so far as I know,
are the only metals which have hitherto been employed in the
experiment described at the commencement, on being exposed
to the action of the air, are quickly covered with a slight film of
invisible oxide, the presence of which is deduced, in a very satis-
. factory manner, from certain electrical phenomena. Now, it is
known that the emissive power is much stronger from oxides
than from the metals themselves. It may happen then, that
the streaked surface, presenting a greater number of points of
contact to the air, is more oxidated than the polished surface,
and thus augments its radiating power by the simple effect of
oxidation, without the more or less regular arrangement of the
superficial parts having any thing directly to do with the result.

For ascertaining if this explanation could be maintained, all
that was required was to make the experiment with gold and
platina, and this I speedily did ; when I found that the streak-
ed plates of platina and gold always yielded a much more abun-
dant calorific emission than the polished surfaces of eitlier metal.

Oxidation then, as well as the influence of polish in non-me-

Radiation of Rough and Polished Surfaces. 303

tallic stihstances, being put out of the question, the inquiry still
remains, what is the alteration peculiar to metals which, in these
bodies accompanies the change, more or less considerable, of
the superficial layer ?

It is no other, in my opinion, than a change of hardness or
of density. Jet, ivory, and marble are, in fact, substances
which are almost entirely destitute of compressibility, or at all
events they do not possess, in any sensible way, the property of
permanently retaining the modifications of density and hardness
impressed on them by the action of mechanical force. They
also readily arrange themselves in the form of plates without
being subjected to pressure. On the contrary, the metals are
compressible ; and the common metal plates of commerce are
obtained, as is known, by subjecting the metals to an extremely
severe pressure by means of the hammer and screw. Finally,
experiment also proves that these plates, as well as wires, have
a specific weight, and a hardness superior to those of east metal.
Who is the individual that will tell us, that this augmentation
of hardness and density is uniformly distributed throughout
every part of the mass ? Is it not, on the contrary, probable
that, during this operation, the surface undergoes a pressure
and condensation greater than any other part ; and that the
plate is truly covered by a kind of envelope, whose density and
hardness is superior to that of the internal layers ?

This conceded, it is evident that by streaking the surface of
a plate the less dense and hard parts will be exposed. Upon
turning, then, to the tables which represent the emissive powers
of bodies, it will be at once perceived that these powers follow,
in general, the inverse ratio of their density. Let us admit that,
according to all analogy, the same law holds regarding the dif-
ferent degrees of condensation of the same substance, and we
may hence conclude, that, in producing these small furrows
at the surface of the plate, we must obtain an augmentation of
the radiating power. To this we have to add, that the parts
which compose the superficial layer being loosened by the sepa-
ration of their contiguous particles, must become softer, and thus
acquire, by the diminution of density, an emissive power which
will more nearly approach to the softer layers of the interior.

This being the case, it will result, Isi, that a polished

h

304 Radiation of Rough and Polished Surfaces.

plate of any given metal radiates a quantity of beat so much
greater in proportion as the density or the hardness of its su-
perficial layers is less ; and, S(i, that, in the case of inferior
density and hardness, the increase of the radiating power pro-
duced by the wnpolishing will be inferior to that obtained when
the plate is denser and more thoroughly compressed.

It is almost unnecessary to add, that, for the verification of
these theoretic conclusions, we must avoid employing a metal
which is oxidated at a low temperature, for a plate of metal
of this kind is imbued with a tendency to, augment its emissive
power, which varies every moment with the condition of the
superficial layers, and so much the more as these layers are
soft and detached.

Violent percussion, on the one hand, and a very slow transi-
tion from the state of fusion to solidity, on the other, are the
two means by which we succeed in endowing metallic substances
with greater or less degrees of density. Accordingly, I ordered
two pairs of plates to be made of very pure silver, and gave di-
rections that one of each pair should be hammered to a high
degree, and the other should be cooled down very slowly in its
sandy mould. Out of these I constructed, with the addition of
a metallic bottom, a small rectangular cistern, the sides of which
were united by means of soft solder, so that there might be no
risk of altering their densities or tempers, during the operation.
When so united, the four sides were perfectly polished, which
process had been accomplished by means of pumice-powder and
charcoal, without the help of either the hammer or the bur-
nisher. I then took coarse emery paper, and strongly rubbed,
in one direction, one of each pair of the plates ; the images of
objects which appeared very distinct and bright upon the surfaces
which were left in all their pristine polish were completely ef-
faced upon the rubbed surfaces, which were quite obscure and
covered with striae. The vase, thus prepared, was filled with
hot water ; and the four sides, successively presented to the
opening of my thermo-electrical apparatus, produced the fol-
lowing effects upon the galvanometer :—

The forged and polished plate, . . 10*^
The forged and roughened plate, . . 18«
The cast and polished plate, . . . 13°7

Radiation of Rough and Polished Surfaces, 305

The cast and roughened plate, . . 11^3

In comparing these four radiations, we perceive, 1^^, as to
the polished plates, that the cast metal affords nearly one-third
more than the forged metal ; which most clearly demonstrates
the influence we have assigned to the inferior density ; and, 2c?,
That the effects of the streaking upon the two sorts of plates
differs not only in intensity, as we had foreseen, but also in
Tcind, for if the radiating power of the forged plate received an
augmentation of four-fifths by the roughening action of the
emery, on the other hand, that of the cast silver experienced a
dijwinw^io7i of nearly one-fifth.

This unexpected result, which irrefragably proves the truth
of our fundamental proposition, is most satisfactorily explained
by the theory we have just been developing. For the pressure
of a hard body, such as the emery, upon the soft surface of the
cast metal, somewhat compresses and condenses the rubbed
parts, and makes the bottom of the striae, produced upon the
superficial layer, harder than the whole surface of the corres-
ponding plate.

I have to regret that I had not an opportunity of making
the same expeiiment upon vessels of gold and platina, where
the same kind of manifestations, in all probability, would ex-
hibit themselves upon a larger scale, on account of the very
great difference of density we can impart to these metals by
means of fusion and percussion.

And now, turning to the first observations of the late Profes-
sor Leslie, we observe that the different metallic plates which
he subjected to experiment, gave constantly a greater emissive
power when they were rough and irregular, than when they
were smooth and polished. This being the case, nothing ap-
peared more natural than to conclude, regarding the phenome-
na of the emission of caloric, that, apart from the influence de-
pendent upon the quality of the superficial layers, there was
some peculiar influence dependent upon their degree of polish,
so far at least as the metals were concerned. This was the

t conclusion drawn from the facts observed by Mr Leslie ; and,
notwithstanding, this conclusion — so simple and direct in ap-
pearance, was unwarrantable.
Here, then, is a beacon where needed, against the unfortu*

306 Professor Forbes's Account of

nate precipitancy with which some experimenters hasten to dig-
nify as general laws, the consequences which result from their
first experiments. Sometimes, we have only to take up an in-
strument and use it in some research, in order to stumble upon
some new fact. But in prosecuting the work with becoming assi-
duity, in varying our modes of experimenting, and in analyzing
the phenomena in different aspects, it will most generally be
found, either that the novelty is only apparent, and that the
true explanation may be found among the already established
truths of science ; or if, on the other hand, it turns out to be a
real discovery, it will almost invariably contradict those alleged
general laws which first of all presented themselves to our
minds with so much apparent certainty and clearness. (Comptes
Rendus de I'' Academic des Sciences.)

Account of an Intermitting' Brine Spring discharging Carbonic
Acid GaSf near Kissingen in Bavaria. By Professor
FoKBEs. (Communicated by the Author.)*^

The little town of Kissingen in Bavaria is situated in 49°
50' North Lat. and 9,T 35' E. from Ferro, or 9° 50' from
Greenwich, at an elevation of about 640 feet above the sea.
It is seated on the left bank of the river Saal, which flows
directly from the mountainous district of the Rhon. It is from
30 to 40 English miles north of Wiirtzburg, and 60 or 70
miles due east of Frankfort-on-the-Maine, from which it is se-
parated by the woody and rugged district of the Spessart.
The Kreutzberg, the highest of the Rhongebirge, rises to a
height of 3000 feet, at a distance of 15 or 20 miles, and the
immediate neighbourhood is varied by a continued succession
of hills and valleys, without being actually mountainous.

Insignificant as, until within a very few years, the town or
rather village of Kissingen has been, it appears to have enjoyed
a certain celebrity from remote times, first on account of its
salt- springs, and afterwards from the curative properties of its
mineral waters. We shall not discuss the knotty point whether

♦ Read to the Royal Society, Edinburgh, 7th January 1839.

an Intermitting Brine Spring near Kissingen. 307

the river Saal was the " flumen gignendo Sale foecundum "
described by Tacitus, * signalized by a battle between the
Hermiinduri and Catti ; but certain it is, that early in the
ninth century the salt-works of Kissingen were already of some
importance, and the property of them presented by individuals
to the neighbouring monastery of Fulda. The lower saline or
salt-work of these early times existed on the right bank of the
Saal, opposite to the village of Kissingen, whilst the upper saline
was an English mile higher up the valley, on the left bank,
and corresponded in fact to what is now called the lower sa-
line. At different subsequent epochs efforts were made by the
Prince Bishops of Wiirtzburg, and others, to render the salt
product more valuable, and at present, through means which
I shall presently state in detail, it has become rather a valuable
source of revenue to the Bavarian Government, yielding about
25,000 Bavarian hundredweights of salt annually.

The resort of strangers to the baths of Kissingen (which
are supplied by springs quite distinct from the saliferous
ones), has been traced by the antiquarian zeal of Jager,*f"
back to the middle of the sixteenth century, who has also cited
twelve medical works published regarding them, between 1836
and 1821. The minute history of these springs (which are
three in number, the Ragozzi, Pandur, and Maximilian's
Brunnen) need not detain us, as they do not form the principal
objects of this paper. Within a few years, Kissingen has be-
come a place of fashionable resort for Germans, and especially
for Russians of fortune. The numbers on the Kurliste amount
to 2500 or 3000 annually ; the lodging-houses have augmented
surprisingly in number, and the King has built public rooms
at his own expense.

To understand the full interest attaching to the phenomena
of mineral springs in this country, we must attend to them
collectively, and also to the geology of the neighbouring dis-
trict.

The general course of the Saal may be considered as from

* Ann. xiii. 57. See Jager Geschichte des Stadtchens Kissingen und
seiner Mineralquellen.
t Geschichte, &c. p. 23.

308 Professor Forbes's Account of

NE. to SW., though at Kissingen it is nearly N. and S.
The lower part of the exposed soil is composed of buJiter-
sandstein, the hills are invariably capped with muschelkalk^
in general imperfectly developed, with few and inconsiderable
organic remains. I have sought in vain for any trace of trap
in the neighbourhood ; only a few fragments I have been able
to find, and these probably were carried from the Rhongebirge.
The nearest fixed trap-rocks lie, I believe, beyond Platz, on
the road to Briickenau. Nevertheless, I consider the trap of
the Rhon to be undoubtedly connected with the appearance of
the springs of Kissingen, indicated especially by their mineral
character, and discharge of carbonic acid gas.

The valleys of Kissingen and of Briickenau are nearly pa-
rallel, and are both probably fissures coeval with the elevation
of the adjacent mountain ranges. At Briickenau, powerful
chalybeate waters appear, as at Bocklet on the Saal a few miles
above Kissingen. Indeed, the number of riiineral springs
which accompany the course of the Saal would alone prove its
valley to be a fissure. We have three mineral springs at
Kissingen, all discharging carbonic acid ; then tracing the course
of the river upwards, there are several salt-springs at the lower
saline, next the Theresien brunnen, a sauerling or carbonic acid
spring; then the upper saline at Hausen, then other brine
springs at Kleinbrach and Grossenbrach ; then the steel springs
at Bocklet, four miles from Kissingen ; then a few miles farther,
still upon the Saal, salt-springs at Neustadt and Neuhaus, and
a Sauerling at Heustreu.

Dr Balling in his Description of Kissingen, remarks that the
springs issue at natural clefts in the rocks,* and Kastner ob-
serves that they generally occur at the junction of the muschel-
kalk and bunter sandsteinrj* but both these statements must be
taken with some limitation. It is undoubtedly true, however,
that the medicinal springs of Kissingen owe their appearance
to a fault. As we walk NW. through the town, by the so-
called Kapelle or smaller Roman Catholic church, we come

• Kissingens Bader und Heilquellen, p. 8.
t Kafitner's Archiv. Bd. viii. Hft. 3.

an Intermitting Brine Springs near Kissingen, 309

suddenly upon the muschelkalk at a very small elevation, but
where a number of magnificent fresh-water springs gush forth,
accompanied by the disengagement of gas ; * and if we pursue
the same direction (continuing to rise), we come again upon the
sandstone, shewing that the muschelkalk was depressed vio-
lently. A very careful examination of the neighbourhood of
the upper and lower saline, convinced me that there is no evi-
dence there of dislocation at present visible ; the strata, so far
as exposed, lie horizontally for a great distance, and the process
of boring has detected nothing but continuous red sandstone for
a depth of several hundred feet.

We shall now confine our attention to the great intermittent
brine spring which we proposed to describe, referring to the
others which may illustrate the phenomena in the course of
the narrative.

History of the Spring. — Under the same roof at the lower
saline are three distinct wells, which at one time or other have
yielded brine for commercial purposes, and which must be dis-
tinguished, if we would trace the curious history of the prin-
cipal one connectedly. There is, 1. The Reiche-brun?ieri, which,
in 1800, after being cleared out, yielded 8 cubic feet of water
per minute, containing 2^ per cent, of salt. 2. The Weite
schacht^ which is 6 feet from the preceding, and previous to
1800 yielded 1 cubic foot per minute, but seems then to have
been absorbed in No. 1. These two shafts occur in the eastern
division of the building, beside the pumping machinery. 3.
The Riinde hrimnen in the western division is the one now
alone attended to ; it is also called, from the violent commo-
tion of the gas which it effects, the Soolen sprudd.f

* According to Kastner, this gas is not pure ciirbonic acid, but consists of
Carbonic Acid, .... 25.45

Nitrogen, . . . . . . 66.50

Oxygen, ..... 8.05

100.00
+ From Soole brine, and sprudein to bubble or sputter. The tenu sprudel
is applied j>ar excellence to the turbulent hot spring at Carlsbad.

810 Professor Forbes's Account of

This spring was first bored for between 1785 and 1788,
when the present shaft was sunk. It has a diameter of 8 feet
for a depth of 13 feet 9 inches (all Bavarian measure, 1
foot = .95756 feet English), and to a farther depth of 11 feet

3 inches, it is only 5 feet diameter. Its cubic content is 9^0
feet. From the bottom of the shaft a bore-hole was carried
down to a farther depth of 68 feet, or 93 feet from the brink
of the shaft. It yielded at first 4 cubic feet at 3.14 per cent,
of salt, but continually diminished, so that in 1798 there was
but 1 cubic foot per minute, at 9, per cent., and in 18] 0, it

.ceased to be taken into account in supplying the manufactory.

The Bavarian Government having taken the manufacture

into their own hands (formerly it was farmed), a fresh bore

was resolved to be made, and commenced June 17. 1822. The

existing bore was cleared and carried down with a diameter of

4 inches. The following is an extract from the original journals
of the work, which I translate literally, and which is of great
importance to the theory of the phenomena.

Date.

Depth.

Rock.

REMARKS.

1822.
June 17.

Bavarian
Ft. in.

93 0

21.

26.
27.

103 8

July 12.

140 71

Bunter saudstein

Uncommonly
hard sandstone

Softer, with loamy
strata interposed

Bunter sandstein

Work commenced. The rock
consists of reddish, yellowish,
and also white sandstone, in
strata from 15 to 24 in. thick;
then of soft, clayey, and some-
what micaceous rock, some
inches thick, imbedded in the
harder sandstone.

On the morning of the 26th, an
overflow of water was observed,
which had so increased on the
morning of the 27th, that the
flow amounted to 4 cubic feet,
with 3 per cent, of salt, and a
TEMP. OF 15° Reaumur. The
neighbouring Reiclie Brunnen
(25 to 30 feet distant), yielded
its usual quantity and quality
of brine.

Since the 26th June, the flow has
increased to 8 cubic feet. The
strength 2| per cent.

an Intermitting Brine Spring, near Kissingen. Sll

Date.

Depth.

Rock.

REMARKS.

1822.
July 19.

Ft. in.
156 8|

Bunter sandstein

About noon, the flow, which had
continued uninterrupted since
the 27th June with consider-
able commotion, stopped for
THE FIRST TIME ; and after 10
minutes of repose it recom-
menced as formerly.

... 20.

160 0|

do.

At 20 min. before 4 a. m. the
phenomenon was repeated, and
lasted 20 min.

... 27.

180 6

do.

The per-centage of the brine was
between 24 and 2| ; temp. W R.

... 28.

do.

At 3 p. M. stopped for 20 min.

Aug. 8.

201 111

Hard do.

At half-past 11 the flow ceased,
and returned after 17 min.

... 17.

210 li

do.

74 P. M. Remained 17 min. out.

... 22.

221 lOi

do.

Between 12 and 1 stopped for
37 min. J and again at 4 p. m.

... 23.

224 84

d .

In the night between the 23d
and 24th the spring ceased to
flow twice, but remained only
from 15 to 20 min. out.

... 28.

239 1h

do.

Since the 23d the spring has
stopped more frequently ; three
or four times a-day, and as of-
ten in the night, but at quite
irregular intervals.

Sept. 2.

245 11

do.

During the last 10 days {sic) the
periodical intermittence of the
spring has occurred five or six
times in 24 hours, but at iiTe-
gular intervals. During the
past night it stopped six times,
but during the day not at all.

... 16.

278 3

do.

Per centage 24. Flow increased.
Temp. 14* R.

... 30.

312 10

do.

The flow continues to increase,
but for 14 days the cessation
has not again occurred.

Oct. 10.

323 34

do.

The boring irons broke. A part
were extracted, but 72 feet re-
maining resisted every attempt
to remove them. The work
was consequently stopped.

312 Professor Forbes's Account of

The boring rods left in the hole are supposed to be by this
time entirely oxidated, for in 1826 they were found to have
fallen together so as to occupy a space of only 12 feet.

The flow of brine after the bore was finished amounted to
21 J cubic feet per min. at 2J per cent., and temp. 15° R. At
the same time, the Reiche-hrunn en yielded 8 cubic feet as formerly.
The phenomena of the spring continued nearly as above de-
scribed, with an ebb recurring irregularly, but several times a-
day until the 2d April 1823, when the ebb lasted eighteen
hours, and on the 3d April six hours.

By the 7th July 1 823, the flow had increased to 34| cubic feet
and that of the Reiche-brunnen diminished from8 to 4^ cubic feet.
By many measurements in 1826 and 1827, it appeared that the
flow had increased to 40 cubic feet, at which it has since remained
nearly stationary ; but it had by this time almost wholly ab-
sorbed the Reiche-brunnen. In 1826 and 1827, when the pump-
ing machinery* was placed in the eastern part of the building
for the purpose of conveying the water for evaporation, the
spring first became tolerably regular in its movements which
occurred nearly as in the following example. On the 5th Au-
gust 1826, all the pumps acting, after the flow had proceeded
with more than common vehemence for a quarter of an hour,
the surface became calm, and after twenty minutes, had de-
scended 9 ft. 3 inches in the shaft, the stratum of gas resting
on it and descending with it. At this depth the surface re-
mained still for half a minute, when the flow recommenced, and
after thirty-seven minutes the water stood as at first. All this
time it is to be understood that the pumps were acting, which
of course tends so far to accelerate the depression and to retard
the ascent of the water in the shaft.

The duration of the ebb was for some time observed day
and night (the pumps also working). From the 15th to the
30th September 1826, the spring ebbed eighty times, or five
times daily. The periods of ebb (including the times of fall-
ing and rising) amounted within the same interval of time to
165 hours ^5 min., or 10 hours 22^'g min. in 24 hours. From

* This consists of eight pumps, which are moved by a water wheel, and
raise the brine out of the sliaft for the purpose of evaporation.

an Intermitting Brine Spring, near Kissingen. 313

the 1st to the 15th October 1826, it ebbed 84 times, or daily
5/y times ; the time of ebb amounting to 129 hours 54 min.,
or 8 hours S9\i min. in 24 hours. From these data and expe-
riments on the diminished discharge due to the ebb, the daily
product of the spring is estimated at 48034 cubic feet, or
2001^ per hour, or 33.604 per minute.

For these particulars of the history of the spring I am en-
tirely indebted to the kindness of Mr Halbig, inspector of the
Royal Salt-works, who at different times examined the records
of the establishment, and extracted for me all the information
I required. During the last twelve years little change appears
to have taken place ; I proceed, therefore, to state from my
own observations the phenomena which it presented in the
summer of 1838, when I was, for five weeks, an almost daily
visitor of the spring, and often more frequently. I have con-
sequently watched it under every phase which it presents.

Phenomenon of Intermittence. — It has been already remarked,
that the regular intermittence of the spring only commenced
after the pumps had been applied to carry the water to the
evaporating houses ; and the fact is not to be doubted, though
it is not a little singular, that the recurrence of the phenomena
at all times depends materially on the number of pumps at
work. The description of the phenomenon as usually observed
by myself (and such as I understand it has been for many
years), is therefore to be understood as applying only when five
or six pumps are at work.

When the spring is in full flow, its appearance is very striking.
The great shaft of eight feet in diameter is filled with water,
agitated in the most violent manner by the torrents of gas (al-
most pure carbonic acid) which it discharges. It resembles a
small pan of water boihng on a very hot fire just as rapidly as
is possible without overflowing. Whilst this turbulence is at
a maximum, the gas abruptly ceases to flow, and in a few se-
conds the surface of the water in the shaft is perfectly tranquil.
The water descends (this effect the pumps alone would pro-
duce) and continues to do so, at first rapidly, then more slowly,
until it has subsided nine or ten feet : this point has but just
been reached, or for a very short time, when a sudden welling
up of the water first, and then of the gas, is observed in the

VOL. XXVI. XO. LII.—APRII. 18^39. X

SI 4 Professor Forbes' s Account of

bottom ; the shaft fills very slowly, and the flow of water and
gas continue for a long time progressively to increase, not ap-
parently attaining their maximum until the water is at its full
height, which requires from thirty to forty minutes after the
first return of the stream. It remains in a state of violent agi-
tation for about two hours, or somewhat more, when the pre-
ceding cycle of phenomena is repeated.

I must not omit to mention certain hollow sounds {dumffe
T67ie), about which much has been said and written, stated to
be audible both at the descent and flow of the water, resem-
bling the report of very distant artillery or drums. I have of-
ten listened for these without hearing them. I have, however,
once or twice perceived them when the gas began to be dis-
charged pretty briskly, and am disposed to attribute them to
concussions of the great column of water occasioned by partial
disengagements of gas.

The extreme improbability of the unanimous report I re-
ceived, that the frequency of the intermission depended upori
the number of pumps at work, and that its regularity was in a
great measure destroyed if these were stopped altogether (as is
the case in winter), aitd the importance of such a fact upon the
theory of the phenomenon, led me to examine it with the
greatest attention : a register was kept by order of the autho-
rities, of the time of ebbing and flowing of the spring, com-
mencing on the 10th of July 1838. This was kept by the
persons officially stationed there, connected with the baths. I
arrived at Kissingen on the 22d, and examined this register al-
most daily afterwards until the 24th August, so as to confirm
its general accuracy. I believe that the observations were
never forged, and were generally within a few minutes of the
truth. The results of an attentive examination of it are the
following : — (1.) That even when the same number of pumps
worked, there is a considerable deviation from the average time
of ebb or flow, amounting occasionally to a fourth or fifth part.
Thus fifty-three observations of the time of flow, whilst five
pumps acted, give a mean duration of 2 hours 46 minutes ; but
in five instances it exceeded 3 hours 30 minutes, and in one in-
stance fell below two hours. (2.) The periods of flow seem
usually to have been greater in the afternoon than in the morn-
ing. (3.) When the number of pumps was suddenly and

ail Intermitting' Brine Spring, near Kissingen. 315

notably increased or diminished, there is almost invariably a
corresponding change observable in the periods ; these becom-
ing shorter as the number of pumps was increased, and vice
versa. (4.) I noticed that in the register a period of flow was
inserted as continuing on the 1st August from 55 minutes
past 7, to 50 minutes past 2, or for 6 hours 55 minutes. Sup-
posing that a period of ebb had been omitted, I applied to the
superintendent for information, and learned that there was no
mistake, but that in consequence of the machinery having been
lor some reason stopped for half a day, the flow had continued
nearly twice as long as usual. (5.) The following is a synop-
sis of the observations.

2, 3, or 4 Pumps. 5 Pumps. 6 or 7 Pumps.
Number of Observations of Flow, 33 53 27

Of Ebb, 52 68 30

Time of Flow, . • . 3 h. 20 m. 2 h. 4G m. 2 li. 32 m.
... Ebb, . . . Oh. 21m. 0 li. 19 m. 0 h. 16 m.

I conceive therefore, that, amidst all the irregularities of the
observed times, the general point is pretty clearly made out,
that the periods vary inversely with the number of pumps.*

T was very desirous to watch the spring when wholly disem-
barrassed from machinery, and left to itself, and at length on
the 24th of August my wish was gratified, and the pumps were
stopped. Circumstances prevented my observations being so
minute as I wished, but they entirely confirmed what I had
previously heard, and found some difficulty in crediting. The
pumps having been stopped at 6i p. m. on the 23d, and the
spring not thereafter watched until next morning, it ebbed at
7 hours 10 min. a. m. ; on the 24th it only recommenced its
flow at 9 h. 15 m., or after a period of 2 hours 5 min. in-
stead of about 20 min. as usual. The spring was not watched
all forenoon, and when I arrived at 1 h. 65 m. it was al-
ready low, standing at 11 feet below the brink, and perfectlyf still.
Hence it is evident, that the water is actually reabsorbed by the
artesian bore which emitted it, for there is no other outlet from
the shaft. At 2 h. 4 m. it began to flow very slowly, with

• It is only fair to state, however, that the observations with three pumpa
and those with four being separated, the former were found to give rather
smaller periods than the latter.

316 Professor Forbes' s Account of

t
some discharge of gas; but this lasted but a short time,

and at 2 h. 30 m. all was again still. At 2 h. 45 m. it re-
commenced suddenly and with great force, so that the shaft
was filled in less than 20 min., there being no pumps to draw
off the Avater as it is supplied (in which case the ascent usually
occupies 45 min.). A narrow tin tube with a funnel-shaped
mouth having been lowered, so as to cover the aperture of the
pipe connected with the 298 feet bore in the bottom of the
shaft, the water and gas spouted to a height of many feet above
the surface of the ground, shewing that were the pipe carried
up instead of discharging itself into the shaft 8 feet wide, we
should have a spouting fountain closely resembling the Geysers
in its phenomena.

According to the testimony of the persons on the spot, who
have abundant means of observing the phenomena during
nearly half the year, when the weather does not admit of the
usual process for evaporating the brine, and consequently the
pumps are not in use, the regularity of the spring under these
circumstances ceases ; the flow lasts 3, 4, or 5 hours ; and the
ebb, 1, 2, or 3 hours.*

It is very important to add, with reference to the phenomenon
of intermission, that several springs in the neighbourhood seem
to partake of this character, and that almost all which have
any mineral impregnation likewise discharge carbonic acid
gas. The most remarkable spring perhaps, is the Schdnbo7'n
Quelle, at Hansen, about a mile beyond the Runde Brunnen
which we have described. It is also an artesian well, bored in
1836 to a depth of 550 Bavarian feet, with a view of obtain-
ing a stronger brine ; but this end has not yet been attained.
It contains only 1 J per cent of salt. Its period of overflow
was very short, and recurred every 7 min. ;-|- but latterly this

* The inspector of salt-works kindly promised to have a register kept for
me during the autumn, after the pumps had ceased to work. This, if it
reaches me, I shall add as an appendix to this paper. The following state-
ment was given to me on the authority of the same individual. I translate
it literally. " It has been observed, that when the water of the Saal stands
60 high as to fill the shaft at the time in wliich the spring is in full flow,
the periodic cliange goes on as usual ; but if this happen whilst the water
ebbs, there occurs no periodic change until the Saal ceases to flow into the
shaft."

+ Pickel Geschichte des Saltz und Luft Brunnen, &c. ; Kastner, &c. The '
man who bored it, described the overflow (which perhaps arises from a dis-
charge of gas alone) as recurring every 8 or 10 minutes xrhilst thepunqjs are kept

an Intermitting Brine Springs near Kissingen. 317

irregularity seems in some measure to have ceased, for I watched
it for a long time together, without perceiving any change in
its level ; it is, however, very inconveniently closed ; I could
only judge by the sound that tliere is a constant discharge. of
gas. A variation in the discharge of gas is evident, but ir-
regular, in the Ragozzi and Pandur springs at Kissingen, pro-
bably depending on the state of the barometer, like the blowers
of inflammable gas in our coal-mines. At Bocklet (four miles
from Kissingen) there is a periodicity in the chalybeate springs,
stated to resemble exactly on a small scale, that of the salt spring
of Kissingen. It is probable that the whole series of springs
connected with the great line of fissure of the Saal Valley
already mentioned, will be found to partake of the periodic
character.

Temperature of the Spring. — The Soolensprudel or Runde
Brunnen, is stated by Kastner, as having had, in December 18S6
and January 1837, by a mean of three experiments, a tempe-
rature of 19°.5 Cent. = 67^.1 Fahr., the temperature of the air
being 7°.5 Cent. = 45°.5. During my stay at Kissingen in July
and August 1838, I frequently measured the temperature with
every precaution, during different conditions of the spring, with-
out finding any difference greater than the possible errors of
observation. I always used two thermometers, marked A. 1.
and A. 2. by Adie of Edinburgh, of which the former having
its freezing point unchanged, may be considered as the more
correct, and on one occasion I compared these with a standard
by Troughton, of which I knew exactly the error, and a ther-
mometer by Greiner of Berlin. The following observations
will illustrate this constancy : —

Troughton
A. 1. A. 2. Corrected. Greiner.

July 23. 5 p. M. Just before the Ebb,

24. 11a. m. An hour after flow,

25. 7 P. M. AVell just filled,
28. 2 hours after flow, 65 .1 65 .6 65^2 65».2

Aug. 2. 15 min. after flow, still

near the bot. of shaft,
14. 1 hour after flow,

at icork ; but, as at the Sprudel, at other times quite irregular, ebbing for per-
haps half a day. Its habitual state is that of ebb, whilst that of the other is
flow. The operation of boring was recommenced shortly before I left Kis-
singen, and no overflow had then taken place. The shaft, 554 Bavarian
feet deep, is entirely in Bunter Sandstein. It is thought that the bore
may at last reach the deposit of salt itself, or a much richer source of brine.

Troughton

A.l.

A. 2. Corrected.

65«.0

65°.4

G5.0

65.4

65 .0

65.3

65 .1

65.6 65^2

65 .0

65.4

65 .0

65.5

318 Professor Forbes's Account of

Now, according to Dr Balling's observations in 1834-5-6,
made at 6 a. m., 2 p. m., 7 p. m., communicated to me by
himself, the mean temperature of the air at Kissingen may be
stated approximately at 8°.8 Reaumur = 51°.8 Fahr., and even
this on account of the choice of hours may be considered too
high, and 51° assumed as the mean temperature of Kissingen.*

I made as many observations as possible upon fresh-water
springs in the neighbourhood, with a view to illustrate this very
high temperature of the brine spring, but unfortunately, with
one or two exceptions, these are insignificant in supply.

FRESH WATER.

Date.

Position of Spring.

Temp.

REMARKS.

July 28.

Bodenlauben, \\ miles

46.3

Situated in an exposed position

from Kissingen

at a very considerable height
above the Saal ; not sufficient,
however, to account for its re-
markably low temp. It is a
good spring, and flows into a
deep well : probably it had not,
in the month of July, attained
its mean temperature.

... 31.

Siisse Quelle, in the
Kurgarteu, at Kissin-
gen

51.5

In the evening after rain.

Aug. 1.

Do. do.

51.6

In the morning at 8.

... 13.

Do. do.

52.0

At 1 p. M. Fine weather.

... 1.

Pump-well, opposite
Salt-office Ober Saline

51.1

At U A. M. 60 feet deep.

At Hausen, in the vil-

51.9

Small spring, but flows con-

lage

stantly.

In a garden near the

50.7

Rises in a shady place into an

chapel (Kapelle), in

artificial tank.

Kissingen, on the right

hand side of road in

ascending

...

On the left hand side

51.0

A magnificent spring before re-

of the road, just be-

ferred to. Taken at 3 different

low the chapel

points with the same result.
It rises from the fissure between
sandstone and muschelkalk,
with discharge of gas. The
town of Kissingen is supplied

from thence.

... 25.

Do. do.

50.9

• I find the temperature of Fulda, also situated in the neighbourhood of
the IthoDgebirge, and at no very great distance from Kissingen, stated in
Kamtz, Meteorologie (II. 88) at 8°.3 Reaumur or 50°.7 Fahr. on the autho-»
rity of U years' observations by Heller.

an Intermitting Brine Spring near Kissingen. 319

Date.

Position of Spring.

Temp.

REMARKS.

Aug. 14.

Cascaden Thai

48.4

In a very shady place, at some
elevation ; a good spring.

... 18.

Groritz

49.0

Small, but well enclosed.

... 19.

Reiterswiesen

50.2

In a shallow, stagnant well.

... 20.

Klaushof

52.2

Small and bad.

... 22.

Grossenbrach

48.5

Pump well.

These springs were all observed, so far as I know, at the spot where they
rose, and I have rejected those not so taken.

MINERAL WATER.

Date.

Position of Spring.

Temp.

REMARKS.

July 27.

Kissingen mineral spring

(I.) Ilagozzi

51.3

At 4 P. M., after considerable

hS Pandur
(3.) Maximilian

51.3

rain.

49.3

Aug. 13.

(1.) Ragozzi

52.1

At 1 p. M., after fine ireather. The

(2.) Pandur

51.7

Ragozzi and Pandur are saline

(3.) Maximilian

49.8

and chalybeate. The Maximi-

... 27.

(1.) Kagozzi
(2.) Pandur

51.6

lian contains little solid matter,

51.5

but sparkles extremely with

carbonic acid. It is the least

abimdant of the three, but the

discharge is not exactly known.

July 29.

Theresien Brunnen,

51.7

A Sauerling or carb. acid spring ;

near the Ober Saline

an artesian well, 4 in. diameter,
135 feet deep. Observed at 7
p. M.

Aug. 13.

Schonbom Quelle at

53.9

Artesian well, 554 Bav. feet deep.

Hausen

described above. Brine spring
yields 14 per cent. Dischar^ae
small. Formerly intermittent.

... 16.

Booklet, 4 miles from

Kissingen

(1.) Stahl Quelle
(2.) Schwefel Quelle

49.4

Contain much iron, and discharge

48.4

carbonic acid gas.

... 23.

Bruckenau principal

47.9

Briickenau does not belong to

spring

the environs of Kissingen, be-
ing at a distance of 18 miles,
and in quite a different valley ;
I presume also at a greater ele-
vation. It is an almost pure
chalybeate water, and dis-
cliarges carbonic acid.

Aug. 25.

Salt spring at Kleinen-

50.3

Small. Discharges li cubic feet

brach, 2 miles from

per min.

Kissingen.

S20 Professor Forbes's Account of

On these observations the following remarks present them-
selves. (1.) Whilst the mean of all the temperatures would
not differ materially from the temperature of the air observed
by Dr Balling, a discriminating examination of them would
lead us to place the mean temperature of the ground at
Kissingen considerably lower. For, though in the months
of July and August, deep springs may shew a temperature
too low, not having yet reached their ascending mean, the
majority of surface-springs will then be too high.* (2.) We
find, in general, but little difference between the tempera-
tures in the first tables and those in the second, the circum-
stance of mineralization and discharge of carbonic acid not
appearing to accompany a materially higher temperature, as it
frequently does.

But when we consider how these observations bear upon the
point we have specially in view, the relative temperature of the
great brine spring, the result is very interesting. Scarcely in
a single instance, besides the Schonborn Quelle (of which, as we
have seen, the depth is 550 feet), does the temperature reach
52*, whilst that of the Runde Brunnen is QB". Were we to at-
tribute the excess of from 13° to 15°, to the depth of the arte-
sian well solely, and thence compute the rate of increase in
descending, we should greatly err ; for, in the first place, the
water of the far deeper Schonborn Quelle has an excess of only
2° or 3° (owing partly, no doubt, to the feebleness of its flow),
and in the next, it is quite certain that the temperature of the
Runde Brunnen is wholly independent of the particular depth of
its bore. It is in this respect that the journal of the work
already given (page 310), is so interesting. We trace the gradual
accumulation of the water ; we find that the periodical charac-
ter of the spring commenced when the depth was 156 feet ;
that we have no right to conclude that the chief volume of
water comes from the bottom, for no sudden increase was ob-
served ; the augmentation of flow was gradual as the water

• Perhaps, however, the discrepancy is really owing to the sheltered
situation of Kissingen (as the springs in its immediate neighbourhood have
almost the temperature of the air), whilst the surrounding country in which
many of the springs above mentioned are found, is, though not very ele-
Tated, comparatively bleak and exposed.

an Intermitting Brine Spring near Kissingen, 321

slowly opened for itself new channels, connected with its arti-
ficial outlet. At a depth of little more than 100 feet, the
temperature was already 15° R. = QS^"" F., and diminished af-
terwards to 14' (6*3^° F.), and finally increased to 15°, when
the work was concluded, at which nearly it has since remained.
But from the earlier history of the work, I trace a yet more
marked proof of the independence of the temperature and the
depth of the bore. In the little work of Pickel, professor of
Chemistry at Wijrtzburg, I find that the Reiche Brunnen (see
page 5, but which the writer does not seem very clearly to dis-
criminate from the new or Runde Brunnen) yielded a copious
flow of brine coming from a depth of only 5Q feet, which in
1782 had a temperature of 16^° R. (69° F.) and contained
3J per cent, of salt, but which in 1800 had fallen to 10^
(544° F.) with Ij per cent.* We thus see that the tempera-
ture of water, obtained comparatively near the surface, was
higher than that at the depth of 323 feet in the new shaft.
This shews the necessity of discriminating the depth from which
water flows, and the depth of the well with which it happens to
be connected,-|- a point too often overlooked in estimating the
progression of temperature as we descend.

In addition to its other peculiarities, the brine spring of
Kissingen is to be considered as a true hot spring, as much so
as if it had any higher temperature, the warmth not depending
on the contingent circumstance of its finding its exit by an
artesian well. Considered in this point of view, we naturally
look for the cause of its thermality to the neighbourhood of
the volcanic focus of the Rhon, and the evidence formerly
alluded to, of the valley of the Saal being a great fissure ;
yet, after all, we find sufficient anomalies to puzzle us.
Why no thermal springs are found in the whole district of
the Rhon besides, J why the other springs which appear so
nearly connected with this one, as to discharge the same
gas, and to partake of its character of periodicity, have so

♦ Pickel Geschichte des Salz-und Luft-Brunnens, p. 6.
t Bisclioff, Warmelelire, Leipzig, 1837, p. 252.
X Kastner.

S22 Professor Forbes's Account of'

much lower a temperature, are points of which I can offer no
elucidation.

Products of the Spring, — These are gaseous and mineral.
The gas consists, according to Kastner, of almost pure carbonic
acid, there being also a trace of azote. A pound of water is
combined with 30^ French cubic inches of gas. But this gives
no conception of the quantity which is evolved wholly uncom-
bined. I have in vain thought of a plan to estimate roughly
its amount. Even the first few minutes of returning action of
the spring in its feeblest state after ebb, are sufficient to fill the
entire shaft (containing 920 cubic feet) with gas, and the tur-
bulence of its disengagement during full action I have already
attempted to describe.

The carbonic acid gas has been applied as an external sti-
mulant to the eyes, ears, and the whole body. For this pur-
pose, a large inverted iron funneL 5 or 6 feet in diameter, is
dropped by a pulley, so as to float on the surface of the water,
and the gas collected under it is conveyed by means of a flexi-
ble tube into a neighbouring building, where gas baths are
regularly administered. When it is to be generally applied, it
is introduced into a wooden tub, in which the patient (clothed
as usual) is seated, and, from its density, it soon fills the tub,
and flows over upon the floor, through which it sinks by venti-
lating apertures properly distributed. Its effect is exciting
and agreeably warm over the whole body, and is found to be
useful in cases of local relaxation of the vascular system.

The mineral discharge of the spring consists of from S5 to
40 Bavarian cubic feet of brine per minute. On the 24th of
August, I found it to be about 37 cubic feet, but the experi-
ment did not admit of great accuracy. Its specific gravity that
day was 1.0157, at a temperature (as well as I recollect) of
16° Reaumur, which is nearly its mean value. Both the quan-
tity and quality are regularly measured and registered by the
Government authorities presiding over the salt-works. The
sp. gr., I was informed varies from 1.0164 to 1.0130, and lower
when the water of the Saal gets in. I was likewise assured
that it is not densest after warm weather, but rather in a damp
season, and when the Saal is high. Here follows Kastner's

an Intermitting Brine Spring near Kissingen. 323

analysis of the solid matter in 1000 grains of water, which we
may compare with that of sea-water by Dr Murray ♦ (sp. gr.
about 1.028.)

Chloride of Sodium,

Potassium,

Lithium,

Magnesium,

Calcium,

Bromide of Magnesium,
Iodide of Sodium,
Sulphate of Soda,
Carbonate of Magnesia,

Lime,

Iron,

Manganese,

Organic Acids,
Ammonia,
Silica,
Earthy matter.

0077
0015
0963
0070

Solid matter,
Carb. acid.

JCisaingeD.
Grains.

14.00020
0.12750
0.02500
3.18700
0.52000
0.00820
trace
3 29530
0.83500
0.21500
0.04645
0.00015

0.11250

22.37230 gi-.
2.06380

24.43610

Sea water.
Grains.
22.001

4.208
0.784

3.316

30.309 gr.

The analogy of composition with sea- water is certainly strik-
ing. I believe that most kinds of rock-salt contain much less
muriate of magnesia, which gives to sea-water its disagreeable
flavdur.t

The process of converting the brine into salt is worthy of a
brief description. The expense of evaporating by fire so weak
a brine, would evidently be too expensive to be profitable, in a
country destitute of mineral coal. The well known plan of
suffering the water to drop from twig to twig, off vast open
stacks of thorns, arranged so as to expose as much surface as
possible to the air, and thus evaporating it at common tempe-
ratures, is therefore resorted to. The water is pumped from
the well by eight pumps or fewer, depending on the dryness
of the weather, to the top of a vast wooden shed which contains

* Turner's Chemistry, 5th edition, p. 1031.

t See Dr Henry's paper on the Analysis of Salt, PhiL Trans. 1810.

324j Professor Forbes"'s Account of

two parallel artificial hedges of black thorn stacked in hori-
zontal layers, each hedge being on an average S5 feet high, and
{3J feet thick. These sheds {Gradirhduser\ containing double
hedges, are no less than Q^^^^ feet in length, or near a mile
and a quarter. A wooden trough is carried along the upper
part of each thorn hedge {Dornenwand)^ into which the spring-
water is pumped. Cocks are placed at intervals of 4 feet in
these troughs, which convey a regulated supply of water into
small wooden gutters 4 feet long, with narrow slits in the sides,
through which the water trickles upon the bed of twigs below.
Having dropped through 25 feet of thorns, it is received in a
wooden box placed at the bottom, from which it is pumped up
to the top of the next adjacent section of the building, through
which it again drips, giving off to the atmosphere a fresh portion
of its pure water, and this operation is repeated five times.
During this process, much solid matter is accumulated on the
thorns, which after a year or two become thickly incrusted with
carbonate of lime. Nearly all the oxide of iron contained in the
water is deposited during the jftrst fall, and marks those hedges
with its characteristic ochreous colour. It is a mistake to suppose
that the use of all this complicated apparatus is to free the
water from the small quantity of earthy matter which it contains:
it is solely for the purpose of economizing fuel. The value of
the process may be judged of from the fact, that after six falls
properly conducted, the brine contains ITJ per cent, of salt,
instead of 2|. To obtain this effect, the supply of water must
be nicely proportioned to the fitness of the atmosphere for the
process of evaporation (Gradirung),

From 26000 to 28000 hundredweights of salt are extracted
from the brine, which has undergone this operation,* or even
30,000.t What a vast charge of water the atmosphere hascarried
off by this easy process ! By the analysis, we see that 14 grains of
muriate of soda are combined with 976 of water, or 70 times
its weight ; hence, besides all loss in manufacturing, 210 mil-
lions of pounds of water are annually disposed of; and since

* Maas, Kissingen und soine Heilquellen, Wurtzburg, 1830, p. 38.
tPickel,p. 11.

an Intermitting Brine Spring near Kissingen. 3J25

the brine is seven times stronger after spontaneous evaporation
than before (rising from 2i to 17J per cent.), six-sevenths of
the water are driven off during this process. Hence, during
the part of the year in which the manufacture continues (for
during many winter months the frost renders it impossible),
the atmospliere actually absorbs 1 80 millions of pounds of
water in the form of invisible vapour. The volume of this is
three millions of cubic feet in round numbers, a quantity which,
if we suppose it uniformly distributed over the area of the
thorny stacks, through which it percolates, would reach the
astonishing depth of 68J feet, or more than twice and a half
that of the thorns themselves. In other words, the an-
nual evaporation from a given area of thorns (piled to a height
of 25 feet), is a stratum of water nearly 70 feet in thickness,
independent of the large proportion which must go to waste.

The air in the neighbourhood of the evaporating houses is of
course sensibly affected by this process. It is cool in the
warmest weather ; and in the neighbourhood, several species of
plants occur, native commonly only near the sea shore.* The
smell of chlorine may occasionally be distinctly perceived.

From the accumulation of stalactitic matter, the thorns re-
quire to be renewed once in two years, but even then they are
not profitless ; the earthy concretion is broken off and employed
on the roads, and the thorns being burnt, the ashes afford an
admirable manure from the quantity of alkali which they
contain.

The evaporated brine at 17^ per cent, is conveyed in wooden
pipes to the pans at the Ober Saline, where it is boiled first to
saturation (26^ per cent.), during which process it deposits an
earthy sediment (ScJilamm). It is then removed to another
pan and farther evaporated, yielding good salt. Pure muriate
of soda being less soluble than the sulphate of soda and muriate
of magnesia is first deposited. At a certain stage the mother
liquor (Mutterlauge) is poured off, and again evaporated at
twice ; the first operation affording inferior s?alt, such as is used

• Arenaria marina, Triglochin inaritinuira, Poa distans, Salicoraia her-
bacea, Eryngium maritimum, Arenaria rubra et marina, Scirpus setaceua
BaUin(/y Kisiiingens Biider und Ileilquellen, Stuttgart 1837, p. 10.

S26 Professor Forbes on an Intermitting Brine Spring.

for cattle ; the evaporation to dryness yielding an intensely
bitter salt, consisting chiefly of muriate of magnesia, which is
afterwards employed in the manufacture of Epsom salts and
sal-ammoniac. The analysis of the mother liquor of 36 per
cent, strength, is, according to Kastner, the following :

Chloride of Sodium, . ^ . 56.0100 grains.

Potassium, . . . 20.0000

, Lithion, . . . 4.0000

Magnesium, . . 250.8400

Muriate of Ammonia, . . . 0.0047
Hydrobromate of Magnesia, . 1 .3500
Hydriodate of Soda, . . . trace.
Sulphate of Soda, . . • 0.1225
Magnesia, . . . 31.8500

364.1772
Water, 635.8228

1000.

Kastner states that he could detect not a trace of kreosote.

This terminates what I have to say regarding the salt spring
of Kissingen, which I cannot help regarding as one of the most
remarkable in Europe. I had intended to have added some-
thing respecting the theory of its intermission. I have not,
however, been able to satisfy myself of any sufficient explana-
tion of its singular phenomena, which is not too complex to
give much hope of its representing the natural process accu-
rately. There can be little doubt that the interposition of
columns of gas conveying pressure somewhat on the principle of
Hero's fountain, acts an important part. It might even be
possible to devise a mechanical theory which should explain the
singular fact of the action of the pumps accelerating its periods ;
but I have not thought it worth pursuing in detail.

. Edinburgh, 2\8t November 1838.

( 327 )

On a Method of obtaining the greatest possible degree of Exacti-
tude from the Data of a Survey. By Mr Edwaud Sang,
F. R. S. E., M. S. A., Civil-Engineer and Machine-maker,
Edinburgh. Communicated by the Society of Arts.*

A FEW weeks ago I laid before the Society of Arts, some re-
marks on an erroneous method of using the theodolite, which
is practised in the Ordnance Survey of the British Isles. In
the course of these remarks it was shewn, demonstratively, that
by leaving out certain readings and computations, a superior
degree of precision would have been obtained.

In the present paper I mean to continue the subject, and to
inquire whether the like degree of scientific skill which charac-
terizes this fundamental operation, has characterized the other
departments of this national work. And to do this more ef-
fectually, I shall contrast the processes actually used, with that
one which gives the greatest possible chance of accuracy. I
cannot agree with Mr Bevan, who, after having detected fla-
grant errors in the altitudes of certain stations, yet expresses
" great confidence in the general result of the terrestrial depart-
ments ;"" for, having exposed an error affecting the operations
of the great theodolite, I need not profess to feel any confidence
until I have examined the grounds on which that confidence is
to be founded.

To some it may appear an invidious task, that of scrutiniz-
ing the Ordnance Survey ; but these persons can hardly be
aware of the interests which are at stake. The progressive im-
provement of Astronomy ; the determination of the form of the
earth ; and one element towards the knowledge of the law ac-
cording to which its density increases downwards — these are
the expected fruits of such an operation : and as the expense is
a heavy one even for a nation, we must either obtain these
fruits now, or have our expectations deferred for an indefinite
term. The matter is not individual but national — not even
national — for it is of interest to the whole human race. These
fruits are not to be expected from the general and statistical
details of the survey, but from the fathoms and the seconds of

♦ Read before the Society of Arts for Scotland, 26th Dec 1838, and
J 6th January 1839.

828 Mr Sang on Optimum Surveying,

it : riot from a passable acquaintance with elementary trigono-
metry, but from a profound and skilful application of its laws.
The interests of science are involved, and 1 imagine it to be
proper that a set of operations already of fifty-four years' stand-
ing, and as yet unproductive of a single definite and trust-worthy
result, should be thoroughly sifted. The errors which have
been pointed out by Tiarks, Beven, and Ivory, imperiously
call for inquiry.

In the year 1822, Dr Tiarks discovered that the longtitude
of Falmouth is 4s. 4 (time) different from that given by the
surveyors ; and a short anonymous article, satirical in the high-
est degree, though unintentionally so, inserted in the Phil.
Mag., April 1824, ascribes the discrepancy — to what? to the
errors of the survey .'* by no means, but to an irregularity in
the figure of the earth ! The result of Dr Tiarks' examination
is this, that the rate of error is 1'' for every 4' of longitude ;
that is, in the length of a line an error of one part in two hun-
dred and forty ; and this attributed to an irregularity in the
figure of the earth !

In the number of the same Journal for August 1824, there
is an article by Mr Bevan, containing the following statement.
Altitude of mouth of fixed cannon at King's Arbur, or the
upper end of the base on Hounslow Heath.

Feet.
As determined by Mr Bevan, .... 90^

Vol. i. page 173. Trig. Surv. . . . . 91 i

266 118

Vol. iii. page 307 132

exhibiting a difference of 40 feet among the statements of the
surveyors, and this concerning one of the cardinal points of the
survey ; the upper end of the base line ! Does this not call
for inquiry ?

In July 1828, Mr Ivory takes the matter up ; and with
what intention ? The result of the survey between Dunnose
and Clifton had been, that the earth is a prolate and not an
oblate spheroid. Another irregularity in the earth's form !
Mr Ivory, however, clearly shews that an erroneous use of the
angles observed had led to this startling conclusion ; and, not
following the example of Dr Tiarks, scruples not to declare

Mr Sang on Optimum Surveying. 329

that the earth is right, — the surveyors wrong. Having thus
run his first parallel, he continues his operations, and, by a
series of papers inserted in the same Magazine, he threatens to
luidermine and blow up the defences.

At length in October 1828, a shot is heard from the place ;
but it is like that which was once used in the defence of Stam-
boul ; it shakes the wall more than the enemy''s battery does.
Dr Tiarks has undertaken the defence of the survey, and has
shewn that even if the theorem of Dalby were true, it is entire-
ly unfit for the purposes to which it was applied by the Ord-
nance Surveyors. He shews, in fact, that the theorem used
by them, gave from certain data an oblateness of yjg, but that
an error, either way, of 1" in the data would augment the ob-
lateness to g^g, or reduce it to ^l-g. One single second can
do all this ! A keener satire on the skill of the surveyors than
this of Dr Tiarks, it is impossible for me to pen : it can only
be matched by a late appeal to the evidence of the heliostate
in support of the exactitude of the survey.

I shall be told that these are old errors, and that they are in
course of being corrected. But in reply I urge, that the notices
of them are later than the latest volume of the English survey ;
and that their exposure preceded the attempt to rectify them.

Without pretending to class my own labours along with
those of Tiarks, Bevan, or Ivory, I may remark, that the error
pointed out by me a month ago is one of as much importance
as any of the others ; nay, of more importance, for those are
errors which affect merely the deductions, and which can be re-
medied by a suitable discussion : but this is one which shakes
our confidence in the data from which these deductions flow,
and which can only be removed by an appeal to the scroll field
books, or by an entire remeasurement of the angles. The
obliteration of many of the stations prevents the latter method.

There are two distinct purposes for which an extensive sur-
vey may be undertaken ; the one, purely geographical, which
has in view the delineation of the district surveyed upon a
model of the earth, and which, consequently, involves the de-
termination of the earth's figure ; the other, local merely, being
directed to the comparison of the dimensions of the district, and

VOL. XXVI. NO. Lll. — APRIL 1839. Y

330 Mr Sang on Optimum Surveying.

therefore those of the earth also, with the standard measure of
the country. These two purposes are entirely distinct from
each other ; the first of them can be attained independently of
the second ; but the second necessarily implies the first.

This general proposition, which, as a matter of course, should
influence the whole management of a survey, is one that ap-
pears to me to be self-evident. Yet, as the want of distinction
between these two purposes constitutes the great defect of the
surveyors' calculations, I shall endeavour to render the state-
ment clear and undeniable, and to point out the inevitable con^
fusion which arises from not attending to it.

That the geographical department of the survey is indepen-
dent of the other, is evident from this one consideration, that
jf there had been no standard in the possession of the Royal
Society, the second department would have had no existence.
Yet still the geographical department would have been unaf-
fected.

The mere angular data of an extensive survey, without the
measurement of any base, ought to be sufficient to determine
the figure of the earth, and the proportions which the surface
of the district bears to the entire surface of the globe.

Suppose that, in the neighbourhood of the equator, an entire
circuit of triangles could be obtained, and, connected there-
with, another complete circuit round one of the meridians, it is
clear that, without reference to any arbitrary national standard,
the relation might thence be obtained between the circumference
of the equator and that of the meridian ; and, further, if the
whole surface of the globe could be covered by a net- work of
trigons, all the peculiarities of the earth's figure might thence
be discovered.

The powers which belong to this complete system of trian-
gulation, are shared by any portion of it. Throwing out of
view, for a moment, the difficulties which arise from atmo-
spheric refraction, the following is a description of a simple and
direct procedure, from which all the effects of local attractions
are removed.

ABC being three stations seen from each other, the horizoi
tal and vertical angles observed at these stations would enabl

Mr Sang on Optimum Surveijing. 331

us to determine the angles of the
. jj rectilineal trigon ABC, and from

these we could compute the pro-
' portion of the sides. D being

another station, the usual obser-
vations would enable us to deter-
mine the angles of BCD, and also
^ the inclination of the plane BCD

to ABC. Having referred the
.J) positions of A, B and C to an ar-
bitrary system of co-ordinates,
the position of D could be found in reference to the same system.
And so on we might proceed to many new stations. Having thus
obtained the x, y, z's of a great number of points situate on {or
near) the surface of the terrestrial spheroid, we might then seek,
by the known method of minimum squares, for that spheroid
whose surface would pass most nearly through all the stations.
In this way the proportions which exist between AB and the axis
of the spheroid would be known, and even the inclination of
AB to the meridian, and that without a single astronomical
observation. Then, comparing the length of AB with the na-
tional standard, the dimensions of the globe in French toises or
in English feet would be known. Now here, although it would
be convenient to express all the distances from the commence-
ment, according to the national measure, that accident of con-
venience does not change the nature of the process, or render
the knowledge of the earth's form dependent on the measured
length of the base. This method is, on account of the irregu-
larities of refraction, useless in practice ; but in idea it serves
excellently to bring the true character of the operations before
the mind.

The horizontal angles being the only ones that are much to
be depended on, it becomes an interesting problem to discover
whether these alone be sufficient to give the form or dimension
of tlie earth ? On the supposition that the earth is a sphere, we
may devise a very simple metliod of computing its radius.
There is this known property of spherical polygons, that their
surfaces are proportional to the excess of their angles above
those of a plane polygon having the same number of sides.

y2

3S2 Mr Sang 07i Optimum Surveying.

The ratio which the observed spherical excess bears to 720°, is
that which the entire area of the polygon bears to the surface of
the globe. But, unfortunately, that spherical excess is found
to be so small as to merge among the errors of observation,
so that nothing but the rudest approximation to the size of the
earth could be expected from this source. Unless, indeed, the
survey were very extensive, embracing many thousand square
miles, some other element than the horizontal angles must be
introduced, the relative inclinations of the horizons at various
stations form the best additional data ; and as these cannot be
had from direct observation, on account of the great curvature
of rays of light nearly horizontal, we must deduce them from
observations on stars near the zenith.

Here, then, is the method which circumstances compel us to
adopt in measuring the dimensions of the earth. We first con-
nect, by a system of trigons, one station with another at the
distance of fifty miles or upwards, and then determine astrono-
mically the latitudes and longitudes of these stations. The
data thus obtained are sufficient for our purpose.

The distance, determined astronomically, has to be compared
with that determined by triangulation, but here arises a diffi-
culty ; as the triangles are spherical, the sides cannot be com-
puted by the usual formula of plane trigonometry ; thus, ha-
ving measured a base and its two adjacent angles, we are not in
a condition to compute the other two sides, unless we know the
dimensions of the spheroid upon which we work ; but the di-
mensions of that sphere are the very objects of cur research.

The method followed in the trigonometrical survey is this :
assuming that the degree of the meridian (or equator) is
60859-1 fathoms, the spherical excess for each trigon has been
computed from a previous approximate determination of its
area, and this spherical excess is employed to assist in the com-
putation of the unknown sides. Now, essentially, this opera-
tion is one of approximation merely, and the error caused by it
is a function of the error in the original supposition ; this ought
to have been rigorously scrutinized, and the computations re-
done according to the Rule of False of our common treatises
on arithmetic; until the computers were satisfied that the error
is too small to be noticed.

Mr Sang 07i Optimum Surveying, S3J5

But in all the principal triangles the three angles were actu-
ally observed, and the observations have been corrected by the
above named assumption ; and it is really a matter of doubt
whether such a correction be allowable, or whether, admitting
the nearness of the assumption, the disagreement of the obser-
vations with it ought not to have been taken as evidence of
the incompetence of the instruments employed.

In the surveys of 1787-88 and 1791-94, which were made
with the great theodolite, the entire amount of computed sphe-
rical excess is 90^^03, the entire amount of observed excess is
72''.25, and not merely is the sum total less than the computed
sum total, but almost all the terms are so. According to this
observed spherical excess on a district of some 1700 square
miles, the degree of the earth's circumference ought to measure
68,000 fathoms nearly. Again, in the survey of 1795-96,
which was made by an instrument of half the size, the spheri-
cal excess observed was S2''.75, that computed W.Q9., while
the greater number of the terms are in excess. This would
give for the length of the degree 57,000 fathoms nearly. Of
the remarkable contrast in the precision of the two instruments
I shall have occasion to treat in an after paper ; here I shall
only ask if it was proper, amid such instrumental deficiencies,
to carry the angles corrected for computation to hundredtk
parts of a second ? Ought a sailor boy to correct the altitude
given by his ebony octant, for the solar parallax ?

The error of procedure which I have just noticed is one of
quality, not of amount ; I have brought it out here for the
purpose of rendering more apparent another of the same kind,
but of greater magnitude.

In vol. i., p. 154, there is an investigation given concerning
the sum of the azimuths of two stations. Supposing this in-
vestigation to be correct (it is in reality grossly erroneous), the
surveyors deduced the difference of longitude of the stations ;
exactly inverting the above method of spherical excess ; only
that the included surface is more extensive, having one of its
corners at the North pole. The error thus actually introduced
was one of 200 fathoms in the degree of longitude. I have al-
ready quoted Dr Tiarks's statement, that an uncertainty of 1" in
the observed azimuths would cause a doubt as to the oblate-

^4 Mr Sang 07i Optimum Surveying.

ness of the earth altogether ridiculous. The investigation,
however, is erroneous, as may be detected by any beginner in
stereometry; it has been justly characterized by Mr Ivory,
as " the greatest delusion that has ever prevailed in practical
mathematics."

There is, by the way, something very curious connected
with the operations carried across the channel. On all the
partial triangles the curvature of the earth is carefully allowed
for, yet in the computations for determining the easting and
southing from Greenwich, computations extending over larger
surfaces, it is entirely neglected !

Leaving the survey for a little, I shall now proceed to shew,
first, in the case of plane surveying, how the computations must
be carried on so as to give the greatest exactitude ; and in do-
ing this, I shall merely use a method already well known, and
applied to much more intricate matters.

While carrying on an extensive survey, the operator is care-
ful to determine the position of each new station, by the meet-
ing of several lines drawn towards it. If only two lines be
used, its position, indeed, may be set down, but there will be
afforded no means of knowing what degree of accuracy has
been attained ; a third, fourth, or fifth bearing affords means
for checking: the determination from the first two. It is not
uncommon to compute the position of several intersections, and
to average these for the true position ; nor is it even unusual
(see Trig. Surv. passim) to reject those results and observations
which do not happen to jump with the rest. I shall shew a
single operation by which the optimum position may be found,
whatever may be the number of intersecting lines.

The positions of a number of stations, A, B, C, D, &c. ha-
ving been accurately determined,
we seek to ascertain that of a new
station, N. For this purpose, we
observe the bearing of N, as seen
from several of these stations or
the directions of the lines A N,
B N, C N, he. The intersection
of any two of these will give,
supposing that there is no error,

Mr Sang on Optimum Surveying. SSS

the position of N. But, in practice, there are many sources
of minute error ; so that
a magnified view of the
point N may be this, in
which N may represent
the true position. Per-
pendiculars drawn from
N iijxjn the lines marked
A, B, C, &c. would re-
present the errors, in aim,
of the different traverse
lines ; and these perpen-
diculars divided by the distances of the stations would give the
angular errors. Let N a be one of these perpendiculars, the entire

measure ofinaccuracy would be 2 ( ^ai ) • But at different sta-
tions accidental circumstances may have given peculiar chances
of precision (the methods of estimating these I shall treat of in
two succeeding papers) ; and hence, taking all circumstances in-
to account, the entire measure of inaccuracy will take the form

where a is a quantity known from the field operations. We
have, then, so to determine N as that this integral may be the
least possible.

Denoting hy x ,y ;x ^y ; &c., the rectangular co-ordinates
of the points A, B, &c., and by AN, BN, &;c., the bearings of
N, as seen from A, B, the value of the perpendicular N a
will be

N a =3 (a-^ — Xj^) sin AN — (y^ — y^) cos AN
and hence, taking every cause of inaccuracy into account, the
best position of N will be found by solving the equations
. ^ sinAN' -sin AN. cos AN

. ^ sin AN. COS AN, ^ Cos AN = .

the solution of which will give o:^, y^.
In this inquiry I have supposed that the positions of the sta-

836 Mr Sang on Optimum Surveying.

tions A, B, C, &c., have been absolutely determined ; but these
positions also may be liable to uncertainty. The whole sys-
tem of stations are connected by a series of traverse lines ; and
the question of optimum determination may be extended thus ;
to find those positions of a multitude of stations which may
best agree with the observed angles.

To suit the above investigation to this inquiry, we have only
to denote hy ah the probability of error in aim, as known from
the field-book, on the bearing AB. We shall then have
^ ^ sin BA 2 . ^ sin BA . cos BA ,

^'^''^ -^6^ ('''^-^b) =2 __ (,^_ y^)

. 2 sin BA . cos BA , ^ -, cosBA^

^ ^ sin AB- , - X. sin AB . cos AB .

^ ^J sin AB . cos AB , ^ cos AB^

^^"^ " ^p ("" ~\= — ^t-cye-yA)

etc. etc.

Here, then, are two equations for each station, and it might
therefore appear that the positions of all the stations may be
determined from the bearings alone ; but it must be observed
that the entire sum of the equations depending on J ^ is zero,
as well as of those depending on dy^ so that two of the num-
ber need not be counted : and again, that, as there is no abso-
lute term, only the ratios x — x :y — y -.x — x -, ii — y ^

^ J A B -^A "^B A C »>'a "^C'

&c., could be got. Thus we are at liberty to assume co-ordi-
nates at will for any one station, and to introduce one arbitrary
condition ; which arbitrary condition might be the length of
the base line, or the distance, any how determined, direct, in
latitude or in longitude, between two stations.

The capabilities of this method include the best possible so-
lution of every case that can occur in plane surveying.

If, for example, the latitudes of some stations, the longitudes
of otliers, and both latitudes and longitudes of a third class, had
been determined by other processes susceptible of a certain
degree of precision, these determinations could be combined
with the bearings. Let X be the so-determined latitude of
A J and a the chance of error on it, the term

*A — X

Mr Sang on Optimum Surveying. SSI

would need to be added to the equation depending on dx ;
and so of any others. As now the sum of the equations would
no longer be zero, and as absolute terms would now be intro-
duced, there would be no need of, nor any room for, arbitrary
conditions.

Again, for example, if several distances have been measured
at various parts of the survey, these also could be introduced.
Thus, if the distance, among others, from A to B had been
measured and found to be AB, with a chance of error a (3, the
terms

2cosBA r . , „ , )

2 sin BA f , , , )

^^^''-^^ iN/(K-^B)^ + (2'A-2/B)^)-AB}

. 2cosAB f ^^^^ >

^ 2sinAB f ^ ^ >

^y^;—--! same. J

would need to be added to the proper equations.

In this way there would be no distinction between the Base
and a base of verification. The computations would not be
carried on in one district from one base, in anotlier district from
another, there would be no particular set of trigons selected for
computation, and not a single observation would be omitted, or
even have too much or too little importance attached to it.

There are still other cases in which this same method might
be useful ; one in particular, on account of its frequent occur-
rence in practice, I cannot omit to mention.

When engaged in coast surveys, we have often to find the
position of a station by angles observed at the station itself.
For this purpose, a line of signals is made along the coast, and
the angles subtended by these are observed with a reflecting
circle. This is particularly useful in obtaining soundings, but
being susceptible of a great degree of precision, it is often used
for finer purposes. It is a matter of regret that, from the obli-
teration of the surveyors' marks on the hill tops, we are de-
prived of great facilities in fixing geographically the positions
of places.

338 Mr Sang on Optimum Surveying.

When three signals are observed, only one result can be ob-
tained, but when four or more are noticed, the combination of
these three and three would give so many positions. If, in fact,
upon two signals as extremities, an arc be constituted, contain-
ing the measured angle, that arc will be one locus of the sta-
tion sought. In this way, by taking each pair of signals, we
obtain a new locus. These loci will not, probably, all meet in
one point, and the true position of the station must be sought
in a manner analogous to that already given.

The observations at the station N do not give the bearings
of the signals, but only the differences between the bearings :
hence, assuming the direction of an arbitrary line for the meri-
dian, the observed bearings N A, N B, &c., will differ from the
true bearings by an angle v peculiar to the station N ; so that
the true bearings are (NA — i'), (N B — v), &c. ; and here v is
not to be taken as a small correction ; it may be an angle of any
magnitude.

These bearings, referred to the other extremities of the lines,
become augmented by 180°, or the signs of their sin and cos
changed : hence, the perpendiculars let fall from N upon paral-
lels down through A, B, &c. are of the form

— (-^"n — -^a) sin (N A — v) + {y^ — y) cos (N A^ — v)
and thus we must have for a minimum the sum

_N A_^j4 isin(NA — v)cos(NA — v) I

an an ^ '^ /

+ 2 . (""iZlt . cos (N A — v) ^
\ an ' /

where p also is a quantity to be determined : we should thus
have the equations —

= 2 2. J? .''^ licos2(NA-v)

an an

Ja:j,;5.!!iZp^.sin(NA — v)2 = 2.^-^-.sm(NA— v).cos(NA — v)
a » « »

Syj,;2.!!Ll^sin(NA — v).cos(NA — v) = 2.5^— ^^-^cos(NA — 0'

J

Mr Sang on Optimum Surveying. 339

from which three equations, the co-ordinates x^^ y^^ and the ar-
bitrary y, which is the angle between the assumed and the true
meridian, can be determined.

It often happens that merely angles are observed at a station.
That is to say, an assumed direction is taken for the meridian ;
or the bearings are taken by the help of a bapk observation.
Hence, there enter other questions than those which I have
solved in p. 24, for at each station A, there is an uncertainty a
in the bearings. Allowing for this, the formulae will stand
thus : —

oei' i S _ i ^sm(AB— «).cos(AB — «)

~ ^6^ {cos(AB — a)2--sin(AB — «)«}

a^A;2.^^2— sin(BA — /S)2=2.^^-^sin(BA — S).cos(BA — A)
a2/A;2.!iII^sin(BA — /3).cos(BA-^)=2.?^-?^cos(BA-/Jl2

In these expressions, when the bearings taken at a given sta-
tion have been obtained from a direct astronomical observation,
there is no arbitrary correction a to be applied : but when the
position of the meridian has been assumed merely, or has been
determined by transference from some remote station, the cor-
rection a ought to be used. In the case of pure assumption, a
must be treated as a large angle ; but in the case of transfer-
ence, it may be treated as a small one ; in which case, it will be
sufficient to regard its cosine as unit, and its sine as equal to
the arc.

The above equations used in this way will include the
best possible determination of the positions of the stations,
taking all the circumstances of the angular observations into
account.

I have now described the method of Optimum Surveying as
applicable to plane surveys ; before proceeding to inquire
whether it be capable of extension to geodetical operations, it
may be worth while to glance at the advantages which it ofFei-s,
that we may be fortified against any formidable difficulties.

A net- work of traverse lines has been thrown over the whole
extent of the British Islands ; the bearings of many of these

340 Mr Sang on Optimum Surveying,

have been taken at one extremity or at both, while at some sta-
tions, the angles only have been read. Astronomical observa-
tions, too, have settled the latitudes and longitudes of many
stations. This whole field-work having been completed, we
proceed to draw from it, regarded as one integer operation, the
figure of the earth, and the true relative dimensions of the dis-
trict, and that with all the exactitude of which the matter is
susceptible : and then comparing the measured lengths of the
various bases with their geographical lengths, we discover the
true ratio which the standard yard bears to the axis of the
earth. The measurement of the base would not then be the
foundation of the survey ; and the error in it would not be aug-
mented in proportion to the extent of the district. Nor would
we need to compute from one base for so many miles, and from
the average of that and another for so many more. There
would be no selection of one set of trigons, nor any arbitrary
checking of the results ; our computations would be divested of
their hypothetical character, and unity both of design and of
execution would be given to the whole process.

The general aspect of such a geodetical operation is this,
— The ratio of the earth's Polar to its Equatorial radius, the
geographical latitude and longitude of each station, would be
the unknown quantities ; and the question would be so to de-
termine each one of these, as that no change could be made on
it without augmenting the general measure of inaccuracy, the
sum of the squares of the errors of observation.

To carry through such a computation, we would need to be
furnished with data for the degree of confidence to which each
observation is entitled, and must therefore call for a sheet ex-
hibiting, not the coincidences of the survey, but its discrepan-
cies ; not the nearness with which one base has been deter-
mined from another, but the probable amount of error in the
intermediate angles, as well as those observations which have
been rejected on account of their disagreement with the rest,
in order that we may throw the whole into the pan of an im-
partial balance, which will strike a fair average of them all.

Supposing the origin of co-ordinates to be at the centre of
the earth : x being the intersection of the equator with the
prime meridian ; y that of the equator with a perpendicular

i

Mr Sang on Optimum Surveying. 341

meridian, and z the polar axis : putting also a for the equa-
torial, /3 for the polar radius, the equation of the spheriod is

«*^ ^ «^ ^ /j2
hence, X Y Z being the co-ordinates of any station we have

and for the equation of the horizon there

(X-x) X (Y-y) X ^ (Z-.) X ^ ^
«« ^ /S'* "^ y^ "^

wherefore the equations of a vertical line at that station are

^.(X-x) = ?l(Y-y)=^(Z-=).

hence the latitude and longitude of the station A being known,
its rectangular co-ordinates are thus found.

Putting (A) z= V{a.^ cos lat A- -f /3.2 sin lat A*}

x^ ::::: ,— — . cos lat A . cos Ion A ,
(A)

^A = 7-z\ ■ cos lat A . sin Ion A ,
^ (A)

z. — ,-rT sin lat A
A — (A)

Leading along the vertical at A, a plane inclined at a given
angle AN (the bearing of N from A) to the meridian, the
equation of that traverse plane is

(j'^^a;) {cos Ion A . sin lat A . sin A N + sin Ion A . cos A N J

+ (^A — y) {s^^ ^®^ -^ • ^^^ ^^^ A . sin A N — cos Ion A . cos A N J

— {Zj^—z) {cos lat A . sin A N} = O

whence the value of a perpendicular let fall from N upon the
traverse plane intended to pass through it is

-^ 5 cos lat N . sin lat A . sin A N . cos (Ion A — Ion N)

+ cos lat N . cos A N . sin (Ion A — Ion N) [•

— -^r X \ sin lat N . cos lat A . sin A N
N) \

_'!!z±! « sin 2 lat A. sin AN
(A) ^

This perpendicular let fall from N upon the traverse plane
A N, is exactly analogous to that used in the investigation for

342 Mr Sang on Optimum Surveying.

plane surveys. Dividing it by the probability (A N) that the
traverse will pass aside of the station, and summing the squares
of these quotients taken for every observed bearing, we have
the general measure of inaccuracy ; this is to be a minimum.
The quantities here to be determined are the latitudes and
longitudes of the stations, and the radii a, j8 of the spheriod.
Differentiating, then, according to these unknown quantities,
and separating the terms containing the independent variations ;
observing also, that we are at liberty to take either a or jS as
known, or as unit, we obtain as the most exact determination
of the various quantities sought, the equations —

sin A N

\ sin lat N^ cos lat N \ sin lat A . cos (Ion A — ^lon N)

\sti Depending on b . (3-.

. /n » T ^TN cos A N ) , . , , ^.^ T X TVT9 1 i. A sin A N )
+ sm (Ion A — Ion N) ^ — J- + sin lat N . cos lat N^ cos lat A . — - — v

i /32 . , ^ sin A N
-f 2 . ,^r=^ Sin lat N^ . cos lat A . 5 —

a2_i («2_^2) sin lat A^ . , ^ . . ^ ^ sin A N

-4- 2 . ^-^ — jr^^r^ Sin lat A . cos lat A . s —

' (A)3 e^

= 0.

where the e denotes the chance of error on the bearing A N,
that is the probable distance at which the traverse line will
pass aside of the station.

^d, Depending on longitude of place of observation ; d Ion A.
(1*^ part)

^2 f sin A N
2 . T^ < cos lat N . sin lat A , sin (Ion A — Ion N) . —

COS A. N^ \
H- cos lat N . cos (Ion A — Ion N) — r = ^

3^, Depending on longitude station observed ; 5 . Ion N.

a^ f

2 . Tj^x S — ■ COS lat N . sin lat A sin (Ion A — Ion N)

— cos lat N . cos (Ion A — Ion N) '^^^-^ — r = O

e' )

In these equations (the 2d and Sd) it is to be observed, that
the sign S applies only to part of the survey, and that d Ion A

sin A N

Mr Sang on Optimum Surveying. 343

may occur among equation 3 as well as among equation 2. If A
become in turn an observed station this will happen, in which
case the two equations involving d . Ion A must be added to-
gether.

4!th, Depending on latitude of station observed from ; d lat A.

AN f a* 132

2 . __ J ^.cos lat N . cos lat A , cos (Ion A— Ion N)+ — sin lat N . sin lat A

_ (''-^Tt(f2 1atAy^_ «^^ ,„, 2 lat A I = O
(A)3 (A) J

And, 5th, Depending on latitude of signal ; 5 . lat N.
2. /f^li^^=l5!)sinlatN.coslatN2— -^ sinktNJ X

X ^ sin lat A . cos (Ion A — lonN) — 1- sin (Ion A — Ion N) — ^— i- >

+ 2 . 1 ^^^=^^ sin lat N^ cos lat N --^-^cos lat N I cos lat A . ^i^^

= 0.
To equations 4 and 5 a remark similar to that made con-
cerning 2 and 3 applies.

The observations of the bearings are not, however, the only
data of a survey: the observed longitudes and latitudes of
various stations have to be combined with these. Using capital
letters to indicate the observed latitudes and longitudes, we

have

lat A — Lat A

for the error in latitude at the station A; and for the error
which this will cause in the position of A, we must add
as factor the radius of curvature of the meridian: so that,
roughly estimating this radius, and combining it with the pro-
bable error caused by inaccuracies in the zenith sector, we ob-
tain a probability E of inaccuracy. In this way

(latA— Lat A\^
E /

is the measure of inexactitude, and thus

latA — Lat A

^ E^

falls to be added to the equation depending on d . lat A. Or,

34)4 Mr Sang on Optimum Surveying,

since the observed and computed latitudes may be expected to
agree tolerably —

lat A — Lat A ^ (sin lat A — sin Lat A) see Lat A
= — (cos lat A — cos Lat A) see Lat A

these forms may be used as analogous to the other terms of the
equation.

In the very same way the observed longitudes may be intro-
duced, along with the probable errors in the timekeepers and
lunar tables.

The above five equations, with the additions just indicated,
contain all that is needed for deducing with the greatest possi-
ble probability of exactness, the latitudes and longitudes of the
stations, and the figure of the earth from the geodetical opera-
tions : But a single glance at them is sufficient to convince one
that the manipulation of them is matter of no small difficulty.
Were it not, indeed, from this circumstance that the oblateness
of the earth is small, these equations would be next to unma-
nageable. Proceeding, however, by steps, neglecting first
o? — /S^, then neglecting its second and higher powers u . s .f ,
we may render the computations practicable. It is unnecessary
for me to proceed here to discuss the method of managing such
calculations, as that discussion would form rather a treatise on
geodetics, than a general essay on the manner in which a geo-
detical survey ought to be conducted.

A Series of Facts and Observations respecting the Natural
Causes of Arborescent or Dendritic Figures in the two di-
visions ()f Animal and Vegetable Structures, and in Mineral
Formations, By Sir Anthony Carlisle, F. R. S. Com-
municated by the Author.

These ramifying figures are not the special productions of
living bodies, because they also occur in mineral formations,
and when they are not the impressions of organized structures.

In some instances of organic nature, arborescent figures de-
pend on tubular vessels, as in animals ; but in vegetable struc-
tures these figures are composed of solid woody fibres, while the

On Dendritic Figures. 345

frame work of the wings of insects consists of a solid horny
substance.

For the advancement of natural knowledge, and for the im-
provement of organic physiology, it may be useful to collect
and to collate various evidences, in order to establish the laws
which direct the formation of similar figures in different bodies.

In many cases the progressive steps of physical causation are
more apparent in mineral bodies than in the complicated and
living structures of animals and vegetables ; and these examples
of resembling figures will, therefore, commence with minerals
which present dendritic figures, uninfluenced by the disturbing
actions of vitality.

The most simple, and one of the most common examples of
dendritic figures, occurs in the manufacture of the cheapest
sort of ornamented pottery ware termed the '* Mocha pattern.' »
These picturesque figures are made by children who are entirely
ignorant of the art of design. While the vessel is in the unglazed
state termed Biscuit, it is dabbed in given places with a liquid
pigment which runs by descent, as the surface of the vessel is
inclined, and thus it instantly spreads from trunks into regular
subdividing branches ; the rough surface of the biscuit, and the
gradual thickening of the liquid pigment, producing these ap-
pearances.

Streamlets similarly divaricating appear on the sea- shore
where little pools of wat: v remain embanked by sand. The
water oozing through the sand issues in streams, and these sub-
divide, according to the declivity, into arborescing streamlets,
which sometimes again reunite into larger branches, as in the
anastomoses, between arteries and veins of animal structures.
The same appearances often occur upon clayey or muddy de-
clivities over which streamlets of water flow.

Dendritic figures are also common in many stones which were
formerly regarded as petrifactions of previously organized
structures. In the compact marly limestone, called Lithogra-
phic stone, these figures often occur, and generally on the sur-
faces of laminae, by which it would seem that the ochry pig-
ment had percolated and spread in the same manner as that
described respecting pottery. The moss-agate, certain marbles,
and mocha-stone, exhibit similar dendritic figures. The entire

VOL. XXVI. NO. LII. APRIL 1839- Z

346 On Dendritic Figures.

bodies of certain corallines assume an aborescent character, as
in the Corallina muscosa of Ellis. (See Plate 2 of his work.)

The next examples of arborescent evolutions occur in the so-
lid woody frame-work of the leaves of trees, as displayed after
the membranous or parenchymatous substance has been re-
moved by maceration ; and a remarkable example of an accom-
modated structure of leaves happens in the Ranunculus aqua-
tilts, in which the floating leaves possess an entire covering of
skin, while the submersed leaves are subdivided like those of
fennel, as if the water had stopped the evolution of the skin
rendering the organ more like the gills of fishes.

For the better understanding of physiological, and conse-
quently of pathological, phenomena, it is very important to dis-
tinguish between physical causes of general influence, and the
especial or peculiar causes termed vital, which belong conjointly
to organized living bodies ; and the facts now submitted mvist,
I believe, lead to more exact and practical discriminations as to
the causes of embryotic evolution, the growth of organized
parts, the reparation of laesions, and morbid deviations from
natural structure.

If it be granted that arborescing vessels are only gross ac-
commodations or appliances of convenience in animal function,
and that they always originate under physical direction, and
not from a vital or mysterious necessity, we may assume to
have made one step further in natural knowledge.

These assumptions may, however, be justly supported by the
unquestionable existence of entire living distinct animals and
vegetables, devoid of arborescing vessels or ramifying fibres.
The former occur in dropsical fluids and in uncysted tumours,
whicli are termed globular hydatids ; the latter, in the Tremella
nostoc. These hydatids are so far parasitical that they exist
only in the natural fluids of living animals. The Tremella
nostoc has probably a parasitical origin, since it always ap-
pears upon moist and decayed wood, or on dead leaves in the
spring season.

London, Langham Place.,
October 1. 1838.

" dif

c-

m

WM-.^

#.

!il;l

./^M;: ?il|i' '

f:f

mm

< ^mg

( 347 )

On the Natural History of Volcanos and Earthquakes. By Dr
GusTAv BiscHOF, Professor of Chemistry in the University
of Bonn. Communicated by the Author. (Concluded from
page 81.)

Earthquakes.

EARTHauAKEs, SO closely connected with volcanic phenome-
na, are undoubtedly owing to the same causes. That the pro-
cesses by which they are produced must take place at a great
depth is evident from the simultaneous occurrence of earth-
quakes at places far distant from one another. Some extraor-
dinary examples in this respect are furnished by the memorable
earthquake at Lisbon, on the 1st November 1755, which was
not only felt over a great part of Europe., but extended to the
northern coast oi Africa and the Antilles ; and farther, by the si-
multaneous shocks felt on the 16th November 1827, at Ochotsk
and Bogota, which places are 1900 geographical miles distant
from each other, and are separated both by land and sea.*
Parrotf has calculated that about 700,000 German miles, that
is, nearly one-twelfth of the whole surface of the earth, was
shaken by the earthquake at Lisbon. Stukeley | calculated
from the extent of country over which earthquakes have been
felt, that the force must, in some instances, be 200 English
miles beneath the surface. But Daubeny§ pointed out that we
must not lay any stress on his remarks, because we have reason
to believe that the vibrations may be propagated laterally far

* Von Humboldt's Reise. &c. vol. i. p. 497, and vol. iii. p. 23 and 27.
Yon HoiF, Verzeiclmiss Von Erdbeben, &c. in Poggendorflf 's Ann. vol. xxi.
p. 214.

t Physik der Erde, p. 289. See also Berghaus' Almanack, 1837, p. 106,
on the great extent of this extraordinary earthquake. With respect to
this, it is worthy of remark, that Vesudusj winch was in some excitement on
the morning of the 1st November 1755, became suddenly quiet at the very
hour of the shock ; and that, as Von lloff relates, the column of steam
which rose, returned into the crater. The same happened during the
earthquake in Cakihria. The little volcano of Stromboli, which is continually
active, subsided, and almost ceased smoking.

t On the causes of earthquakes, Philos. Trans, for 1750.

§ Loco cit. p. 388.

348 Prof. Bischof on the Natural History of

beyond the immediate influence of the impelh'ng force. In a
former place, I have also shewn, that the seat of volcanic action
may be looked for at depths far less than Stukeley supposes.
But there is no reason to believe that earthquakes could go on
at greater depths than volcanic actions. Supposing that the in-
terior of the earth is still fluid, and that rents conducting water
extend from the surface to the fluid nucleus, it is easy to con-
ceive that the actions of the steam may be felt at very remote
distances.

We have already pointed out the close connection which
exists between earthquakes and volcanic eruptions. Von Hum-
boldt, in his travels near the Equator, gives several examples of
this. It may not be superfluous to refer here to what this il-
lustrious philosopher asserts generally with regard to these phe-
nomena, at the end of the 4th chapter of the ^d volume of
Tart I. Book 2.*

Every thing seems to shew that earthquakes are caused by
the effort of elastic fluids seeking an outlet. On the coasts of
the South Sea their action is often communicated almost in-
stantaneously from Chili to the Gulf of Guayaquil, a distance
of 600 geographical miles ; and, what is very extraordinary,
the shocks seem to be so much the stronger the greater the
distance from the active volcanos. The granite mountains of
Calabria^ the limestone chain of the Apennines, the county of
Pignerol, the coasts of Portugal and Greece, Peru, and the
continent of America, furnish striking proofs of this assertion.-f*
It might be supposed that the earth would be more violently
shaken, the fewer the openings on the surface which communi-,
cate with the interior. At Naples and at Messina, at the footj
of Cotopaxi, and the Tunguragua, earthquakes are dread(
only when vapours and flames do not issue from the mouth
the volcano. In the kingdom of Quito, the great catastropl
of Riohamba led many well informed persons to believe the
this unfortunate country would be less often disturbed if tl
subterranean fire would succeed in destroying the dome of poi

* See also what Von Bucli says on Vesuxius. Geognosti§che Beobacht.
vol. ii. p. 129.
t Fleuriau do Bellevue, Jouru. de Pliysique, t. Ixii. p. 261.

Volcanos and Earthquakes. 349

phyry of Chlmhora^o, and if this colossal mountain should be-
come an active volcano. At all times, analogous facts have
given rise to similar hypotheses. The ancient Greeks, who,
like us, attributed earthquakes to the force of elastic fluids,
brought forward, in support of their opinion, the total cessation
of earthquakes in the island of Euboa, after the opening of a
chasm in the Lelantic fields.*

The intimate connection of earthquakes with volcanos is not
less clearly proved by the direction which the former take.
With the assistance of a simple instrument (the sismograph)
invented by Cacciatore, and erected at Palermo, it was found
in twenty- seven cases that the shock was propagated in a fixed
linear direction, which coincided remarkably with the cardinal
points. In nineteen cases the shocks were transmitted in a di-
rection from east to west, corresponding with the situation
of Mount Etna, the source of all these subterranean concus-
sions, which lies directly to the east of Palermo. In four cases
it was from south to north ; but, for want of corresponding ob-
servations, the seat of these shocks cannot be determined ; and
it certainly does not seem to have been the effect of chance that
three shocks, which were felt on the 9th February, 30th June,
and 2d July 1831, travelled from the south-west to the north*
east : for it was precisely in that direction, at a distance of
about 70 Italian miles, that the small new volcano suddenly
appeared in the sea, probably on the 2d July. The two latter
shocks were also the very same that were felt with greater
force at Sciacca, on the southern coast, opposite to the new
volcano, t

On the other hand, Boussingault J asserts that the most me-
morable earthquakes in the New World, which ravaged the
towns of Latacunga^ Riohamha, Honda, Caraccas, Laguayra,
Mcrida, Barquisimeto, &c. do not coincide with any well esta-
blished volcanic eruption. The oscillation of the surface,
owing to an eruption, is, as it were, local; whilst an earthquake,
which is not subject (at least apparently) to any volcanic erup-
tion, extends to incredible distances, in which case it has also

* Strabo, lib. i. ed. Oxon. 1807, t. i p. 85.

t F. Hoffman in Poggend. Ann. t. xxiv. p. 63.

X Annal. de Chim. et de Phys. t. Iviii. p. 83.

350 Prof. Bischof on the Natural History of

been remarked that the shocks most commonly followed the
direction of chains of mountains.

In favour of the hypothesis, that earthquakes are produced
by aqueous vapour* penetrating to great depths, the following
circumstances may be adduced. Firstly, as aqueous vapour is
supposed to produce volcanic action, it must be presumed to
be also the cause of earthquakes. Secondly, some hours be-
fore the first shock of the tremendous earthquake at Algiers and
the neighbourhood, the 2d to 5th March 1825, which entirely
destroyed the town of Blisa, all the springs and wells are re-
ported to have been dried up.f Thirdly, earthquakes, though
undoubtedly felt even in the centre of large continents, seem
to produce their most frightful effects in countries not very
far removed from the ocean. But, perhaps, earthquakes may

* A remarkable case which has taken place at the iron-foundiy at Sayn,
proves, that shocks of the earth may be several times repeated by the effect
of elastic fluids. A cylinder 14 feet in height, and 31,395 pounds in weight,
wa'S to be cast. The clay mould having been totally filled up by melted
iron, the latter broke through the ground, and penetrated to the depth of
25 feet into the sandy soil, consequently 1 1 feet deeper than the lower
part of the mould. Some time after an earthquake actually took place,
which shook the whole building so violently, that the workmen feared it
would be seriously injured. About half an hour after, an equally violent
shock happened, and after more than 24 hours a third followed. The local
circumstances of that iron-foundry lead to an explanation of these pheno-
mena. There are at a depth of 23-24 feet under the ground of the said
building, many inclined channels which communicate together, for the pur-
pose of collecting the rain-water. Immediately after the shocks, watery
vapours issued abundantly from the mouth of the channels. These vapours
were evolved by the heat of the melted iron from the water, being in the
ground about 2 feet below the bottom of the channels ; and penetrated
through the joinings of their brick- work. But these joinings being filled up
with mud and sand, offered resistance, and consequently the vapours had to
attain a certain elasticity before they were able to penetrate through them.
It is, however, very probable that the vapours, bearing mud and sand with
them, again stopped up the opening, when their elasticity gradually again
decreased. During the shocks, the steam attained its greatest elasticity,
and thickened the earth which surrounded the heated mass of iron ; and
this circumstance may have imi)eded a new afflux of water. Therefore, after
the first shock, half an hour elapsed ; and after the second, which still more
obstructed the afflux of the water, even more than 24 hours elapsed before
the third and latest shock took place.

t Berzelius, Jahresbericht, 1827, p. 310.

II

Volcanos and Earthquakes. 351

also be produced by gaseous exhalations in the interior of the
globe. At least in many accounts of earthquakes, mention is
made of the exhalation of gases from rents, produced by
them,* and the smell of sulphuric acid and of sulphurous va-
pours, which indicate the presence of sulphuretted hydrogen.f
These last may have occasioned also the destruction of the fish
in the sea, and in lakes, during earthquakes ; many instances of
which are known. The bursting forth of flames from the earth
and from the sea, which is so often mentioned,J also indicates
the presence of inflammable gases. However, although this is
corroborated by the fire-damp in mines, the disengagement
of sulphuretted hydrogen while boring artesian wells, and
the not uncommon exhalations of inflammable gas from the
earth, yet it is difficult to account for their inflammation.
This difficulty would disappear, if observation had found flames
only to occur in really volcanic districts. || But at any rate,

* Von Humboldt, Reise, t. i. p. 499. Von Hoff in Poggend. Ann. t. vii.
p. 292, t. ix. p. 593, t. xxv. p. 76. V. Humboldt believes indeed, that
during most earthquakes, nothing arises from the earth ; but there are
on the contrary, proofs that gases are often gradually evolved from the
ground before and after the shocks. The uneasiness of small animals, or
those whose organs of respiration are rather feeble, before and after earth-
quakes, lead us to infer this. Le Gentil (Nouveau Voyage autour du Monde?
t. i. p. 172) has already obsei-\ed, that animals living in holes, as rats, mice,
reptiles, &c., commonly quit their abodes shortly before earthquakes. Cro-
codiles quit their pools in the Llanos, and remove to the continent, Rdat.
Hist. t. v. p. 57. Von Humboldt moreover relates that dogs, goats, and par-
ticularly hogs, which have a keen smell, and turn up the ground, are sud-
denly affected, and a great number of these latter animals have been found
suffocated during the earthquakes in Peni.

+ Von Humboldt, ibid. t. i. p. 484, and t. ii. p. 73. Von Hoff, ibid. t. xii.
p. 567, t. xviii. p. 46. See also Philos. Trans, t. xlix. p. 415.

J Von Humboldt, ibid. Gehler's Physikal. Wiirterbuch, new edit., t. iii*
p. 804. Also during the earthquake of Lisbon (Philos. Trans, ibid.) and on the
island of Matschian (Hist, de la Conquete des MoUuques, t, iii.p. 318) the
bursting forth of flames is reported to have taken place.

II Von Humboldt mentions flames which rise from time to time out of two

extensive caverns in the ravine of the Cuchimno. This phenomenon was

accompanied, during the last great earthquake at Cuinami, with a continued

. hollow subterranean noise. These flames are more especially to be seen

during the rainy season.

352 Prof. Biscbof 07i the Natural History of

it is going rather too far to take the explosion of fire-damp for
the cause of earthquakes, as Kries does.* It is not impossible,
that what has been taken for flames, if not altogether an illu-
sion, was only an appearance of light, produced by the sudden
expansion of highly compressed gases, exactly the same as is
seen when an air-gun is discharged in the dark.

The heating and boiling up of the water in the sea and in
lakes, the spouting up of streams of water, as well as the ejec-
tion of various substances from fissures in the earth,*]- which
have occasionally been witnessed, may be satisfactorily ex-

* In his prize-essay on the causes of earthquakes.

t Yon HofFL c. t. xxv. p. 73, t. xxix. p. 421. At the time of the earth-
quakes, which destroyed a part of Italy (1702-1703), many rents were
formed in the Abruzzij which emitted a large quantity of stones and then
troubled water. The latter was thrown up higher than the trees in the
neighbourhood. Flames and a thick smoke rose from the neighbouring
hills, which continued three days with some interruptions. Hist, de I'Acad.
an. 1704, p. 10. During the earthquake, the 21st October 1766, which totally
destroyed the city of Cumana, the earth opened at several places in the pro-
vince, and vomited sulphureous water. These eruptions were particularly nu-
merous in a plain, which extends towards Casana^/ two geographical miles east-
ward of Cariaco, and which is known by the name of the holloic land Ctierra
Tiueca) because it seems to be every where undermined by hot springs.
Von Humboldt Keise, t. i. p. 482. During the violent earthquake, which
in one minute overthrew the city of Caraccas, on the 26th March 1813, so
much water was thrown up through the cracks, that a new stream was form-
ed. At the same time the ground was also found covered with a fine white
earth, like volcanic ashes, which had been thrown up from fissures in the
neighbourhood. The eruptions of volcanic masses were still more consi-
derable during the earthquake of Biohamha, 1797. The earth was fissured
at innumerable places, and immense gulfs were formed in some places.
Masses of water rose, filling up valleys 1000 ft. wide, and 600 ft. in depth ;
and also at the same time a peculiarly stinking mud, consisting of vol-
canic matter, accumulated so as to form considerable hills, now called moya.
Wide rents were likewise opened during the violent earthquake in the
north coasts of South America^ last year, in order to give exit to streams of
water which rose. It was often observed, that during the earthquakes,
water with sand, mud, &c., was thrown up from wells, sometimes to a height
of 30 ft. Von Humboldt relates, (Relat. Hist,, t. ii. p. 287) that this pheno-
menon is generally observed during the earthquakes at Cumana. The same
thing happened the 1st Nov. 1755 near Colares (Philos. Trans, t. xlix.
p. 416.), and also during the earthquake in Calabria. (Journ. de Phys. lxii»
J). 263.)

Volcanos and EarthquaJces. 35S

plained by the rising of steam and gases, which may have the
effect either of heating the water, or of throwing out solid
bodies.* The same may be said of the concussions of the
earth which takes place, sometimes in horizontal undulations,
sometimes in vertical shocks, and sometimes with a vibratory
motion, backwards and forwards. The latter of these convul-
sions, called by the Neapolitans, moto vortkoso, is most common
during the greatest earthquakes.

Von Humboldt has proved, by abundant examples, that the
propagation of earthquakes is not confined to any particular
rock, but that the most varied formations are equally favour-
able to it. We infer, therefore, that the seat of earthquakes must
be below all known rocks. Although all the rocks may be
agitated, yet the manner of extension of the shocks in them is
different, according to their particular quality. The earth-
quakes, which have at different periods ravaged Smyrna^'f
Messina,\ Kwgstozvn in Jamaica 1792, the county of Pigne-
rol 1808,11 Calabria,^ Talcahuano in CMU^^^ &c. have always
had a greater effect on diluvium and alluvium, than on rocks.
Houses, for instance, built on sandy ground, were demolished,
while those which stood on rocks were but little damaged.
The shocks therefore act less violently and destructively on
solid and rocky ground than on loose soil, which is unable to
resist, and propagates the shock irregularly. In Calabria^
where the loose soil occurred lying on granite on the declivity

* Thus, during the above-mentioned earthquake on the north coast of S.
Amenca, columns of smoke were seen rising out of the sea, a league from
the shore, and in a depth of about 210 ft. ; and in the night, flames were
seen issuing from the same spot, which illuminated all the coasts of the island.
After each shock, the sea retired, left the ships which wore in the bay
aground, and laid bare the rocks to a great depth ; the waves at the same
time ran to a height of 16 ft. to 20 ft. During the shocks the earth opened
and closed again very rapidly. When tranquillity was restored, a whirlpool
was observed in the sea, as if the waters were being swallowed up in an
immense gulf. The temperature of the sea in the bay was raised, and
bubbles of gas were seen rising all over the surface.

t Hist, de I'Acad. des Sciences, an. 1688. Bufl^on Hist. Nat. t. i. p. 515.

X Spallanzani, Voyage, t. iv. p. 138. 11 Joum. de Phys. t. Ixvii. p. 2.38.

§ Oryktologische Bemerkungen iiber Calabrien &c., 1784.

^ Nautical Magazine, Nos. 49 and 51, March and June 1836.

854 Prof. Bischof on the Natural History of

of the hills, the latter threw off the former, which glided down.
Lastly, there are also instances of shocks extending irregularly
in rocks.*

Many instances present themselves of earthquakes, which, in
extending longitudinally, follow the direction of the rocks.
This is the case, according to Palassou,-]- in the Pyrenees. Re-
markable instances are presented in the phenomena of the 28th
Dec. 1779 ; the 10th July 1784 ; the 8th July 1791 ; the 22d
May 1814, &c. The regions situated more to the south, are,
however, more affected than the chain itself.| Earthquakes
in South America seem also to follow the direction of the
mountains. Thus, that at Caraccas (1812) followed the direc-
tion of the Httoral Cordilleras from E.N.E. to W.S.W.||
That of Cumana VlQl^ presented an instance of the same fact.
The predominant direction of the frequent earthquakes on the
coasts of Chili and Peru^ is also that of the large chain of the
Andes, which is parallel to the coast. § All the older reports like-
wise state, that in these countries their direction is from S. to
N., or vice versa ; and Mrs Graham remarked, that she felt,
during the violent earthquake in Chili 1822, as if the whole
ground from north to south were suddenly raised, and then
sunk again. Von Hoff^ has also related the circumstance,
that the shocks of earthquakes are most common in the same
direction as that of the basaltic masses themselves, and around
a certain distance on either side of the line in which they
occur.

On the other hand, there are many instances of the countries
of Europe having been agitated in all directions, without ha-
ving been influenced by the mountains. Thus, earthquakes
have extended from Upper Italy across the Alps to Switzerland.
That at London (19th March 1750) followed the direction
from W. to E., although the direction of the mountains in

* Berghaus* Almanack fiir das Jahr 1837, P- 72.
t M^m. pour servir h I'Hist. Nat. des Pyren., p. 260.
+ Ibid. p. 910. II Von Humboldt, Rel, Hist. t. v.

. § That at Cumana followed the direction from N. to S., which is ex-
tremely singular, 1. cit. t. iv. p. 16.

% Geschichte der Veranderungen der Erdoberfliiche, t. ii.

Volcanos and Earthquakes. 35B

England is from S.S.W. to N.N.E. &c. Sometimes the earth-
quakes originate from a common centre in a radiating direction
on all sides. That of Lisbo7i (1755), that in Calabria (1783),
and that at Lima (1746), &c. offer instances of this kind.

With regard to the earthquakes in South America, it ha8
been observed that they occur principally in the mountainous
countries. The cause which produces them, seems, as Bous-
singault* believes, to be so constantly in operation, that,' if all
the earthquakes, which are felt in the inhabited countries of
America, could be noted, the earth would be found to quake
nearly without intermission. These frequent movements of the
ground of the Andes, and the slight coincidence between these
convulsions and the volcanic eruptions, induce us to adopt the
opinion of Boussingault, that the former are, for the most
part, independent of the latter. He ascribes the greatest num-
ber of the earthquakes in the Andes to the sinking of rocks in
the interior, which is a consequence of the former elevations of
these chains of mountains. In favour of these suppositions, he
affirms that these gigantic rocks have been thrown up, not in a
doughy, but in a solid and fragmentary state, but that the
consolidation of these fragments bf crystalline rocks might not
at first have been so firm, as not to admit of some sinking after
the elevation. He refers to the Indian tradition which pre-
serves the memory of the sinking of the celebrated mountain
of Capac-Urcu, near Riobamba, the name of which signifies
the chief, i.e. the highest, of all the mountains near the Equator.
It is said that the top of this mountain has sunk in consequence
of a subterranean shock which took place before the discovery
oi America. At the present time Capac-Urcu h lower than
Chimborazo. Boussingault alludes to many instances, in which
it is asserted, that the Cordilleras have sunk. Without taking
into consideration the inferences drawn from barometrical
measurements, made by Boussingault and his predecessors,
which seem indeed to confirm that supposition, we will only

I mention the following circumstances. The French academi-
cians, who, a century ago, were sent to Quito for the purpose
of determining the form of the globe, were very much embar-

* AiinaL de Chim. et de Phys., t. Iviii. p. 83.

S56 Prof. Biscliof oji the Natural History of

rassed in their station on GitaguapicJnncha^ by the snow sur-
rounding their signals. Now, for many years, no snow has
been found on the summit of this mountain. The inhabi-
tants of Popayan also have remarked, that the inferior limit of
the snow covering the Purace is gradually rising, whilst the
mean temperature has remained the same for the last thirty
years, whence Boussingault infers that the Purace is sinking
down.

That masses thrown up in a state of igneous fusion sink
again by degrees, in consequence of their consolidation and con-
traction, cannot be doubted. But even if their elevation had
taken place in a solid state, yet the immense masses of the Andes
have risen from depths, where a pretty high temperature pre-
vails. Supposing the Andes to have risen 24,000 feet in
height, that part of them which is now at the level of the sea,
must have been before the elevation so many thousand feet be-
low it. This part brought, therefore, with itself from beneath,
a temperature which was '^-^^-^ = 470° F. higher than that
which existed at the level of the sea before the elevation. The
same holds good of each part of the Andes, in any depth, so
that every where in erupted masses the temperature surpassed
that of the adjacent rocks by 470° F. Whilst now these
masses gradually lost their surplus of heat, they were contracted.
But this cooling of these masses can, as far as they are within
the earth, only be affected by conduction, therefore a long pe-
riod will elapse for that purpose. That part of the Andes, which
is elevated above the surface of the earth, and is exposed to the
atmosphere, will of course cool a little more quickly. If the
bases of the rocks thrown up be at a great depth below the
surface, their contraction in consequence of their cooling may
be very considerable, and as the elevation of the A?ides is said
to be one of the latest, this cooling and contraction may conti-
nue even at the present time in that part which is within the
earth. It is therefore possible to conceive that these effects are
the cause of the frequent earthquakes in the Andes.

Besides, there is nothing opposed to the hypothesis, that the
powers, whatever they may be, which produced so remarkable
a phenomenon as these elevations, may not even now operate
in a less degree, and occasion the earthquakes so frequent in

Volcanos and Earthquakes. 357

the Andes. The later these elevations are supposed to have
taken place, the more probable will such a hypothesis be.

If further proofs are still necessary to shew that the causes
of earthquakes are only to be sought in' the interior of the
earth, we certainly find them in the fact, that these phenomena
are totally independent of external circumstances. They take
place whether the sky be clouded or serene, in hot as well as
in cold weather,* before or after rain, sometimes with rain,
and sometimes without it. Even the strength and direction of
the wind seem to have no kind of connection with them.-f* Nor
do they seem to be confined to any particular season of the
year, although it is certainly remarkable, that of fifty-seven
earthquakes which were felt at Palermo during a period of

* Many observers allude, indeed, to variations of temperature of the at-
mosphere before and after earthquakes ; but, the academicians of Tunn only
have actually made observations on the temperature in the county oiPignerd.
(Joum. de Phys. t. Ixvii. p. 202.) They found that their thermometer al-
ways descended as soon as shocks had been felt. Thus they felt a vehe-
ment shock in the morning at half-past ten on the 10th of April, and their
thermometer descended till noon from 26° to 22°. In fact it is to be desired,
that farther observations should be made on other occasions, in order to con-
firm or refute the assertion of so remarkable a phenomenon.

t The late F. Hoffman in vain endeavoured to discover in the Meteoro-
logical Journal of the Observatory of Palermo (which included a series of
years from 1792 to 1832, and where particular attention had been paid to the
observation of earthquakes, of which no less than fifty-seven had there been
accurately observed) some peculiarity of weather, which might, with any
degree of plausibility, be supposed to have been connected with the earth-
quakes. The same result was obtained by Domenicq Scink in his memoir
on the numerous earthquakes, which, in the years 1818 and 1819, caused so
much apprehension in the neighbourhood of the Madontan hills. — Poggen-
dorff *s Ann. t. xxiv. p. 50 and 60. In contradiction to this are the traditions
current in many countries. See among others, Berghaus' Almanack, 1837,
p. 97, and following. There seems to be in fact some truth in the opinion,
that earthquakes are most frequent and vehement at the beginning of
rainy weather, and this phenomenon is even ascribed in Jamaica to a locking
up of the pores in the crust of the earth by water, which impedes the rising
of gases. On the other hand, cases have occui-red in which earthquakes
were preceded by a long-continued drought. — Barhara in the Philos. Trans,
t. XXX. p. 837, y. 1718, and t. xlix. p. 403 ; Relat. Ilist. t. ii. pp. 273, 281, and
t. v. p. 15 and 57 ; Ilaus Sloane's Letter with several accounts of the earth-
quake in Peru, Oct. 20. 1687, at Jamaica, 10th Feb. 1688, 7th June, 1692 ;
ibid. y. 1694, p. 78 ; Hist, des Trembl. de Terre, t. ii. p. 442 ; Collect of the
Massachusetts Ilist. Soc, t. v. p. 223.

858 Prof. Bischof on the Natural Historic of

forty years, almost a fourth part happened in the month of
March.* Perhaps the best means of ascertaining whether any
connexion exists between earthquakes and meteorological phe-
nomena, is the observation of the barometer. But Hoifman
was unable to discover anything peculiar or extraordinary,
either in the relative height of the barometer, in the direc-
tion of its motion, or in the extent of the oscillations, during
the fifty-seven earthquakes above alluded to. The oscillations
never went beyond their ordinary limits ; indeed, in most cases
they were very inconsiderable. t Von Humboldt also says that
between the Tropics, on days when the earth is agitated by vio-
lent earthquakes, the regularity of the hourly variations of the
barometer is not disturbed.]:

If aqueous vapours and compressed gases are the cause of
earthquakes, there can be no doubt that hot springs and ex-

* Hoffman, loco cit. p. 52. It is also well known that in other countries,
especially in Chili and the Moluccas, the periods of the equinox, for reasons
of which we are ignorant, are considered as those most favourable to earth-
quakes. During the above-named period of forty years, this law does not
seem to have been applicable to the autumnal equinox in that part of Eu-
rope.

t During the earthquakes the barometer stood decidedly oftener above
the mean than under it. However, Hoffman remarks, p. 56, that during
the only shock of importance which occurred in this period at Palermo, viz.
in March 1823, the barometer remained the whole month constantly below
the monthly mean.

X Reise, t. i. p. 487 ; also Relat. hist. t. iv. p. 19. Likewise Boussingault
in Ann. de Chim. et de Phys. t. liii. p. 82. Other observations have also
proved that the height of the barometer is totally unconnected with the
cause of earthquakes, as for instance those of Don Felixe Castillo Albo, du-
ring the earthquake in Chili in the year of 1822. See also Meyen in his " Reise
um die Erde," t. i. p. 210. Those also made in the county of Pignerol in Sa-
roy by the committee of the academy of Turin, during the earthquakes in
the year 1808. The state of the barometer was also invariable, whilst the
shocks at Lisbon, the 9th December 1755, were very strongly felt at Turin.
Philos. Trans, t. xlix. The observations made on the island of Meleda, near
the coast of Dalmatia, from the 15th November 1824 to the 28th February
1826, which likewise prove, that no connection exists between earthquakes
and the pressure of the atmosphere, are very important, the shocks felt on
this island having been the only ones of their kind as regards length of du-
ration.— Die Detonations-Phanomene auf der Insel Meleda von P. Partsch,
Wien, 1826, p. 204.

Volcanos and Earthquakes, 359

halations of steam and gases, may act as vents, and thus serve
as a protection against them.*

Indeed, the ancients endeavoured to diminish the violence of
subterranean explosions by means of wells and excavations.
What Pliny ,+ the great Roman naturalist, says of the efficacy
of these expedients, is repeated by the ignorant inhabitants of
Quito, when they point out to the traveller the Guaicos, or
clefts of the Pkhincha.X But this is by no means confirmed
by experience,

FarOier reasons in support of the hypothesis which attributes volcanic
phenomena to increased temperature of the interior.

However distinct natural philosophers may consider the
causes of volcanic action, and those of hot springs, yet the
close connexion of these two classes of phenomena refeis us to
one and the same cause. In proportion as satisfactory grounds
can be adduced in support of any hypothesis, which explains
one class of phenomena, so much the more probable does the
hypothesis appear when applied to the other class. Though
the seat of hot springs be concealed deep in the interior of the
earth, and be as little accessible to immediate observation and
investigation as volcanic action is ; yet we may pursue and exa-
mine the phenomena of the former on the surface of the earth,
and every point of time selected by the observer for this pur-
pose proves equally favourable. '

'•' HoflPman is inclined to ascribe the rarity and weakness of the earth-
quakes at Sc'mcca to the numerous exhalations of aqueous vapours, and to the
gi-eat number of hot sulphureous springs, which occur in that neighbourhood,
compared with other parts of Sicily, that are so often and so terribly vi-
sited by these destructive phenomena. Poggefidorfs Annal. t. xxiv. p. 70.

fLib. ii. c. 82 (ed. Par. 1723. t. i. p. 112.)

J Von Humboldt, Reise, t. i. p. 491. In PerUy the earthquakes are less
frequent than in Latacunga, which is ascribed to the great number of deep
hollows which intersect the ground in all directions in the neighbourhood
of the toAvn. Leonhard's Taschenbuch, 1822, p. 917. Von HofF quotes
many instances, in which several wells in llomcy Naples, and Capua, are said
to have diminished or totally paralyzed the effects of earthquakes. But, in
my opinion, an undue importance is ascribed to this eflfect of wells, for it
is hardly to be conceived, that the effects of a cause, existing so deep in the
J^ interior of the earth, should be modified in any considerable degree, by an
^K< opening which penetrates the crust of the earth to so slight a depth.

I

360 Prof. Bischof on the Natural History of

Their wide distribution, the invariableness of their pheno-
mena, the evolutions of gases from many of these, present to
every attentive observer matter of investigation and considera-
tion on their origin, duration, and connexion with other phe-
nomena. If, then, we can succeed in proving that chemical
processes can with much less probability be assigned as the
cause of their being heated, that, on the other hand, the most
convincing reasons shew that their heat is acquired at the expense
of the interior of the earth : then will the hypothesis, which en-
deavours to explain volcanic phenomena from the same causes,
gain no little increased weight. And in fact if hot springs be
heated to such a degree as to attain the boiling point at a cer-
tain depth in the earth, we have but one step to make, by sup-
posing this heat increased up to the fusing-point of volcanic
stony masses, in order to attribute with equal probability,
volcanic phenomena and hot springs to the central part of our
earth.

I must observe, in the first place, as was formerly re-
marked, that, by thermal springs, I understand nothing more
than springs whose average temperature exceeds that of the
soil at the level at which they rise. It is therefore indifferent
whether this excess consists in 1° or less, or in 50° or more. I
can form no other idea of the meaning of the word thermal
springs ; at least, I do not know what degree of temperature
can be laid down as the boundary between cold and thermal
springs, unless the distinction were to be perfectly arbitrary.
Thermal springs (taken in this sense), are very widely distri-
buted over the globe, as I think I have formerly shewn. Nay,
I am convinced that, if we take any district of nearly equal
height above the level of the sea, several of the springs will be
found to exceed in average temperature that of the soil. An
exception of this rule will certainly only be found in those si-
tuations where springs arise at the foot of hills more or less
high, and which have acquired a cooler temperature from the
higher regions.

If, like Professor Daubeny,* we regard chemical processes

* Report on the present state of our knowledge with respect to mineral
and thermal waters. London^ 1837.

i

i

Volcanos and Earthquakes. 361

going on in the earth as the cause of thermal springs, then must
these processes be as universally distributed as the thermal springs.
Those who entertain these views, however, do not surely contend,
that these processes take place near to the surface, else how could
we explain the fact, that, in boring Artesian wells, the greater
the depth, from which the water rises, the higher is its tem-
perature. As little explanation could be given of the circum-
stance, that springs rising in a small district near one another,
often present no inconsiderable difference in their average tem-
perature. In proof of the former assertion, I will cite out of
many other instances that of the hole bored at Riidersdorf near
Berlin^ where water at 74°. 3 F. was drawn by boring to a
depth of 880 feet ; and in proof of the latter, the numerous
springs in Paderborn, whose temperature varies from 49° to
61° F. In the former case, then, these presumed chemical pro-
cesses must take place at least far below the depth of 880 feet ;
in the latter they must be supposed to be going on, either en-
tirely below the situation of the springs at a nearly equal
depth, or at various depths beneath each separate spring. In
the previous case, their different temperatures would be occa-
sioned by one spring running nearer, the other at a greater
distance from, the common source of heat.

Daubeny speaks, in general terms only, of chemical proces-
ses ; if we may, however, judge from a note,* he seems to allude
to the same processes as those which he assumes as the cause of
volcanic phenomena, viz. the oxidation of metals of alkalies and
earths by water. We may pause a little to consider these hy-
pothetical chemical processes, as they ought to inform us
whence the agent, viz. heat, is derived, which is the point in
question.

As the presence of thermal springs is so universal, these me-
tals must be equally so. This hypothesis, especially in the ex-
tent given it by those who maintain it, viz. that the whole nucleus
of the earth consists of an unoxidized mass, cannot be reconciled
with the proportionate density of our earth, as I have already
shewn. Yet, let us admit for a moment tl^e existence of these
metals in a more limited proportion. Their oxidation requires
the access of water ; we must, therefore, suppose as many chan-

♦ Keport, &c., p. 68 and 69.
VOL. XXVI. NO. LII. APRIL 1839. A a -

362 Prof. Bischof on the Natural History of

nels to conduct the water from the surface as there are thermal
springs, or at least groups of thermal springs. Granting all
this, the question yet remains to be answered, why the effects
of these subterraneous oxidations are seen on the surface, in
and near volcanos only ; and why not even a trace of such pro-
cesses can be detected in other places, which yet present innu-
merable thermal springs ? Surely no one will bring forward
the scanty evolutions of sulphuretted hydrogen gas from sul-
phurous waters as proofs of such processes. But, were the
conditions necessary for volcanic activity fulfilled by the access
of water to the interior in each of these channels, then would
the occurrence of volcanic phenomena be much more frequent
on our earth. Or, it must at least be assumed that they were
at a former period as universally distributed as thermal springs
now are ; and that they have left behind a high temperature in
the interior, which warms the springs, and, as Daubeny also as-
sumes, extricates from the limestones, in the interior, the carbo-
nic acid gas so universally present. That this is occasionally
the case, namely that springs do acquire their heat at the ex-
pense of volcanic masses elevated at a distant period is certain-
ly true, and has probably been of still more frequent occur-
rence in former times. I have myself already adduced instances
of this kind. With the cooling of these masses, however, the
thermal springs dependent on them must of [course also cool,
and whether this cooling take place in a longer or shorter time,
jnust depend on the greater or less extent of those masses.

After the preceding remarks, the question remains, whether
it be necessary to assume, in explanation of the universal dis-
tribution of thermal springs, a volcanic activity once so univer-
sally distributed ; or whether their existence cannot be both
more simply and more satisfactorily explained by an increased
temperature in the interior, which is by no means merely hy-
pothetical, but is supported by innumerable facts.

Daubeny says,* " They (the supporters of my views) should
explain to us why primary rocks, traversed, as they so fre-
quently are, with fissures of all descriptions, should not in every
part of the world, and in every kind of situation, give rise to

* Report, p. 70.

Volcanos and Earthquakes. 363

hot springs, by evolving steam from their interior, and why
they never appear to give issue to that class of thermal waters
which I have noticed in Ischia, as being unaccompanied with
gaseous products."

A spring arising from beneath leads us to conclude that me-
teoric water penetrates through clefts which communicate low
down with the former. The experience gained in boring arte-
sian wells shews that a succession of strata is most favourable
for such processes, and from causes easily explained. In what
are called primary rocks, however, no such alteration of strata
is found, because they are not stratified. The usual occur-
rence, viz. the flowing of meteoric water down inclined surfaces
of stratification which appear at elevated situations, and the
rising of this water, by means of natural or artificial channels,
after having been forced down to a more or less considerable
depth, cannot then happen in unstratified rocks. It appears,
nevertheless, that there are granitic rocks traversed by clefts
more or less perpendicular, and communicating low down.
Thus at Aberdeen, in Scotland, water has been drawn by boring
in granite 180 feet below the surface, which, according to Ro-
bison, came from a cleft filled with sand and gravel, and rises
six feet above the level of the earth.* Such a communication
of the clefts low down, must, however, occur but rarely.

If the primary mountain rises above its environs and the
clefts at its base lie exposed, then will the springs flow out of
the clefts. Such an origin of springs, which are not naturally
rising springs, is often observed at the foot of basaltic and tra-
chytic cones, &c.

On the other hand, on the limits between stratified and un-
stratified rocks, where the latter have traversed the former,
and where channels extending to a great depth have been form-
ed in consequence of the contraction of the traversed masses
during their cooling, circumstances favourable to these rising
springs exist, and it is easy to conceive, therefore, that thermal
springs may be found on the limits of these interrupted masses,
but not in their interior.

Let us imagine a stratified chain of mountains consisting of

* Compt. Rend. 183 No. 24, p. 675, and t ii. No. 20, p. 683.

S64j Prof. Bischof on the Natural History of

several formations in a perfectly horizontal position, whose
newest portion (jiingstes Glied) is much fissured, and under
which an impervious stratum lies, then the meteoric water will
penetrate the former fissured stratum, but be retained by the lat-
ter. As long as this horizontal position remains undisturbed,
no rising springs can be supposed to exist in the whole of this
district, and the inhabitants of such mountains could only sup-
ply their want of water by wells (Senkbrunnen). We will
now suppose, that at two points of this district, volcanic masses
are thrown up, and that, in consequence, a partial elevation of
the strata takes place, as is shewn in the diagram, fig. 1. In
this case, the hydrographic relations undergo considerable al-
terations. The consequence will be not only a movement of
the water on the impervious stratum, in the direction of its in-
clination, but meteoric water will also penetrate at A between
the older strata, where, during their undisturbed horizontal po-
sition, not a drop of water could penetrate, and this water will
continue to flow in the direction of the inclination of the ele-
vated strata.* At B, where these strata are also elevated, but

Fij?. 1.

to a lower level, springs will commence rising ; and as many of
such springs may be supposed to exist in a district, as there are
alternations of impervious and pervious strata in these moun-
tains. The most copious springs, however, will be found be-
tween the mass that has been broken through and the oldest
formation of the stratified mountain, because here, in consequence
of the contraction of the former mass during its cooling, a cleft

* The same holds good with regard to the springs of fresh water. Thus
on the Schtc'dbisch Alp springs are always found there where cones of ba-
salt or basaltic tuffa have been elevated on the jura-formation. Plieninger
jn Poggendorflf 's Annal. t. xl. p. 493.

J

Volcanos and Earthquakes, 365

has been formed, which receives the meteoric water flpwing
down on that side of the elevated mountain C, which lies next
to the raised strata. The meteoric water which flows down
through the newest fissured stratum, will now as little give origin
to rising springs as during its earlier horizontal position. If,
now, after the period of this elevation, a stratum of a new for-
mation should occur covering the extremities of the older raised
strata, and extending from B to D, and if, lastly, the new forma-
tion contain impervious strata, then the conditions will undergo
a change. The meteoric water, which penetrates at A, between
each separate portion, will now all issue in the form of rising
springs at B, between the elevated mountain and the new stra-
tified formation which lies at its side. Should any obstacle here
present itself to its exit, the water will even take a retrograde
course B D, and issue at D, in which case the water between
the last formed horizontal stratum and the impervious stratum
lying under the newest raised ones will unite with it. We will
not, however, enter into farther particulars, as many circum-
stances may be supposed to exist which modify the course of
the springs ; and still more complicated relations naturally
arise when, after the deposition of the latest formed stratum,
the elevation and raising are repeated. It will be sufficient to
have called attention to the circumstance, that rising springs
can only exist when the originally horizontal position of the
stratified formations has been destroyed by elevations ; and that
the most copious springs and those which arise from the great-
est depths are found precisely at the limits between the elevated
masses and the raised strata.

Numerous instances can be cited in proof of this assertion.
The Pyrenees and Alps present very characteristic circum-
stances. Thus Pallasou* shews, that not only are the majority
of the hot springs in the Pyrenees^ situated in the great gra-
nitic district at the eastern side, but also that all the others issue
only from hollows of the newer formations, where the granite
rises from beneath, at the foot of the declivities. He shews
also, that even the degree of temperature of these springs de-
pends on the greater or less exposure of their source ; for the

M^m. pour servir k I'Hist. Natur. des Pyr^n^es, 1815, p. 435, 459.

S66 Prof. Bischof on the Natural History of

thermal springs nearer the principal granitic mass are warmer,
while those more remote are colder.

Professor Forbes has likewise pointed out, in an interesting
memoir on the temperatures and geological relations of certain
hot springs, particularly those of the Pyrenees^^ that, in the
departments of the Arriege and the Pyrenees Orientales, where
granite formations preponderate, in almost every case which
he has examined, if springs rise in granite, it is Just at
the boundary of that formation with a stratified rock. In a
great many cases it happens, that part of the springs rise from
granite^, and part from the slate or limestone in contact with it ;
and, he correctly observes, a more striking instance of the im-
mediate connexion between thermal waters and disturbed strata
could not be desired. t

According to the observations of several geologists, the ter-
tiary rocks in the Pyrenees extend horizontally to the foot of
this chain, without entering, as the chalk, into the composition
of any part of its mass. Elie de Beaumont thence infers that
the Pyrenees received their position, relatively to the neigh-
bouring parts of the earth's surface, between the period of the
deposition of green sand and that of chalk (a formation, whose
raised strata, according to Dufrenoy's observations, ascend to the
crest of this chain), and before the deposition of the tertiary
strata of various ages.J We can very well explain, according
to this supposition, why the springs in the Pyrenees issue be-
tween the elevated granite and the raised strata of slate and
limestone. The circumstance above quoted from Pallasou, viz.
that the temperature of springs becomes lower, in proportion to
their distance from the principal granite-mass, may perhaps be
of little importance, since, according to the remark of Forbes,
cold sulphureous springs are to be found, even within not many
yards of others, having a high temperature, and almost an
identical mineral composition. Of this he has met with two

* Philos. Transact, for 1836, p. 575.

t At St Sauveiir and Thiiez, we have the co-ordinate, and, as Forhes
p. G02, rightly thinks, connected phenomena of intrusive rocks, dislocations
or fissures, metalliferous impregnation, and hot springs.

t See Poggendorff's Annalen, t. xxv. p. 26, also p. 58.

Volcanos and EartJiqunkes. 567

examples in very different parts of the chain, one at the Eaux
Bonnes^ where a perfectly cold spring rises within two hun-
dred yards of the principal hot spring of the place, has similar
medicinal properties, and is even more strongly impregnated
witli sulphur. The other example occurs at Las Escaldas^ on
the southern declivity of the Eastern Pyrentes^ where a most
efficacious cold sulphureous spring rises within about one hun-
dred yards of a hot one. When, Forbes continues, to these
facts we add others scarcely less curious, of springs of totally
different mineral composition issuing from nearly the same
spot, and with temperatures from 160° to 180° Fahr., as we
see at Ax and at Thuez^ we are forced to conclude that the
source of mineralization must be independent, to a great extent,
of that of high temperature, and that the arguments, as to the
origin of thermal springs founded upon their chemical compo-
sition, must be to a certain degree fallacious.

The origin of the sulphureous waters in the Pyrenees can
scarcely be sought for in the granite, since no substances are
contained in it which can be supposed to produce such
springs. If such springs are formed by the decomposition of
sulphates by means of substances containing carbon, as is very
probable,* then we must look for the origin of the Pyrenean
sulphureous waters in the secondary formations, perhaps in
some coal stratum, or even possibly in the tertiary formations.
This inference holds, even if the sulphureous springs are formed
in a manner opposite to this view. If, now, the origin of the
springs in question, in other words, if the materials necessary
for their formation be present in one of the newer parts of the
secondary formations, then warm or cold sulphureous springs
will residt, according as warm or cold water penetrates to tjiis
point. The granite plays, then, no other part here, than that of
rendering possible the descent of meteoric water to great
depths, and its re-ascent in consequence of the raising of the

• See my memoir in the Neues Jahrhueh der Chemie und Phys. t. vi. p. 251,
year 1832. The proportionally large quantity of organic matter in the Ptf
rencan sulphureous springs (among which that of Bar^gine, so called from
the valley of Bareges, is remarkable) speaks but little in favour of their ori-
gin from a mountain produced by volcanic fire.

368 Prof. Bischof o/i the Natural History of

strata effected by the granite, which circumstance causes the
heating of these waters.

In this point, I think both theories agree ; viz. that which
attributes the heat of springs to chemical processes, and that
which refers its origin to central heat : for those who hold
the former opinion will doubtless not assign the stratified for-
mations as the seat of these chemical actions, but the granite,
or the parts beneath it. According to both theories, then, the
meteoric water will become warmer in proportion as it ap-
proaches nearer to the source of heat, which can only be sought
for at great depths.

As the subterraneous course of springs is subjected to many
kinds of local impediments, so veins of springs of similar ori-
gin may flow out at points very remote one from another ; and,
vice versa, veins of very dissimilar local origin may issue very
near one another. Nothing is therefore easier to conceive, than
that any stratum in which the materials requisite for the for-
mation of sulphureous springs are present, may be traversed by
springs arising from very various depths, and therefore possess-
ing very unequal temperatures, which circumstance would give
rise to springs of similar chemical composition, but dissimilar
temperature.

Forbes* remarks that the hot springs at Baden-Baden^ on
the border of the ScJiwartzwald^ have a position almost iden-
tical with that which we have so invariably remarked in the
Pyrenees. They occur just where the slate rocks have been
violen.^ly upraised by a curious granitoidal porphyry, which
forms the picturesque elevations near the Alte ScJdoss, and
which passes into a true granite. ' Upon the slate, red sand-
stone lies unconformably. The elevation is among the older
of M. Elie de Beaumont's systems : he expressly states that
the Grcs bigarre is undisturbed.

Relative to the thermal springs in the Pe7inine Alps,
Bakewellf remarks, that, according to his observations, the
exits of all of them lie partly in the primitive mountains of the
central chain itself, partly, and indeed most frequently, at
their extremities, at the boundary between the primitive moun-
tains and the secondary formations.

* L. c, p. 609. t Philos. Magazine, January 1828, p. 14.

Volcanos and Earthquakes. 369

According to the beautiful investigations of De Beaumont,
two different systems are to be distinguished in the Alps, viz.
that of the Western Alps, and that of the principal chain from
the Valais to Austria. Mont Blanc lies at the point of intersec-
tion of these two systems, which here meet at an angle of 45°-
50° ; also Leuk. The period of elevation of those two systems
falls somewhat late. That of the strata belonging to the first
system took place after the deposition of the newest tertiary
formations of these regions, and that of the strata belonging to
the second system between the deposition of the earlier dilu-
vium (des dltesten atifgeschwemmten Landes) and the flowing
of the diluvial streams, and at the time of the transport of
the erratic Alpine rocks^ The most favourable conditions for
the origin of thermal springs evidently exist when the uprais-
ing, caused by the masses thrown up, extends to the newest
formations. Therefore we are justified, under these circum-
stances, in expecting to find many thermal springs in this dis-
trict, and especially at those points where two different systems
of elevation have intersected each other at different periods,
and admitted the meteoric water to penetrate to the interior.
The thermal springs in the Pennine Alps are found partly in
the direction of the principal chain of the Alps, partly, and
more abundantly, in the points of intersection of this system
with that of the Western Alps, and in this last system. Thus
at Naters in the upper Valais (86°Fahr.); at Leuk (115°-
124^) ; in the valley of Bagnes at Lavey, south-east of Bex
(113'') ; Saute de Pucelle, between Moutiers and St Mau-
rice^ in Chamotini ; St Gervaise on Mont Blanc (94°-98°) ;
Courmayeur and St Dididr, on the southern declivity of
Mont Blanc (93°) ; Aix les Bains in Savoy (112°-117°), with
numerous hot springs in the neighbourhood ; Moutiers in the
Tareniaise, Brida in Tarentaise, and some at Grenoble.

It certainly deserves particular notice, that at one point of
intersection (Mont Blanc) so many, and at the other (Leuk)
the warmest springs are met with. Moreover, many thousand
springs present themselves, some in the glacier streams, some un-
der the glaciers themselves, and some may be stopped up. Thus,
most of the above-mentioned thermal springs have been discover-
ed only since Saussure's journeys ; a few very lately, such as

370 Prof. Bischof on the Natural History of

that at Lavey in the bed of Rhone in 1831 ; and others again
have become filled up.

Among those which occur in the continuation of the princi-
pal Alpine chain, I will mention only the two most celebrated,
Pfeffers and Gastein. They are distinguished by their very
small proportion of solid and volatile ingredients. In fact
they are scarcely any thing more than warm glacier-watei'.* It
seems to me that these thermal springs, and probably many
others also in the Alps, resemble exactly those in Ischia,
which Daubeny supposes to be purely the result of the infiltra-
tion of water to spots in the interior of the earth retaining a
high temperature, with this difference only, that these spots lie
somewhat deeper in the Alps than at Ischia, where the
hot masses approach nearer to the surface in consequence
of volcanic activity.

In regions where, after the earlier general elevations, later
partial fractures and elevations have been produced by vol-
canic action, remarkable phenomena also present themselves,
with regard to the existence of thermal springs ; as, for instance,
in Auvergne, and in the vicinity of the Laacher See.

In regard to the former, it is worthy of remark, that the
baths of Mont-Dore are situated almost at the geographical
centre of that group of hills, and also at the position of greatest
dislocation ; two of the centres of elevation, which Elie de
Beaumont and Dufrenoy have pointed out, being found on one
side, and one on the other. The springs issue immediately
from trachyte, which is most remarkably and beautifully co-
lumnar just at the baths. These columns have an extremely
slaty cleavage perpendicular to their axes.t Although the
clay-slate rocks in the district of the Laacher See are very mas-
sive, and so far unfavourable to the penetration of meteoric
water to great depths, yet the number of mineral springs here
is very considerable. They belong, in general, to the class of

* Of the thermal water of Gastein^ 10,000 parts contain only 3.5 solid
matter ; the same quantity of water from the iiiffscAiwe, which flows.imme-
diately out under the glacier, contains only 1, and that from the Aar at
Bern only, 2.2.

t Forbes, loco cit. p. 607.

Volcanos and Earthquakes. S7i

thermal springs, although their temperature is for the most
part but little (often only 1°.5) above the mean of the soiL
The strata of these rocks are raised, and thereby produce a
descent of the meteoric water to deeper points ; nevertheless,
springs of this kind are very rare, wheje no volcanic masses
have been broken through. In these rocks slate-surfaces
(Schieferungs Flachen) are often found, which do not coincide
with the direction of the strata, but intersect them at an acute
angle. These slate- surfaces give origin here and there to mi-
neral springs, and a copious disengagement of carbonic acid
gas.

By far the greater number of the mineral springs there rise
in valleys more or less deeply hollowed, on both sides of whose
declivities, conical volcanic rocks, chiefly of a basaltic nature,
have broken through. Some of them rise immediately from
the clay-slate rocks, frequently from the cleavage surfaces
which separate the strata of clay-slate and grey wacke, and some
come from volcanic masses (trass and volcanic ashes) which
cover these rocks. The circumstance that these mineral
springs seldom, perhaps never, flow out at the boundary between
the erupted masses and the fundamental rocks, gives us an in-
dication where to seek their origin. Tf the strata of the funda-
mental rocks A, A, Fig. 2, are inchned from the erupted volca-

Fig.2.

nic mass B, then a cleft will be formed to a great depth in the
interior of the earth at the boundary between this cone and the
fundamental rocks, in consequence of the contraction of the
former during its cooling. Down this cleft the meteoric water
penetrates and meets the streams of carbonic acid gas developed
in the interior. This latter is absorbed by the water, owing to
the strong hydrostatic pressure exerted at so great a depth.
This forms a water impregnated with carbonic acid, which

372 Prof. Bischof on the Natural History of

effects a decomposition and solution of the stone, and hence
arises an acidulous spring, rich in carbonic acid and carbo-
nates. The deeper the meteoric water penetrates, the warmer
it becomes. Rising springs of water are then produced in
this cleft, through which the concentrated mineral water form-
ed beneath at c, rises to h. If here the direction of the
slaty or stratified surface (Schieferungs oder Schichtungs
Flache) leads down to d, which either has an immediate exit
in the section of the valley a d e^ or runs at a slight depth
below the surface, then the mineral spring will issue, owing to
the pressure of the column of water a h. While the rising
streams of warm water take the course c h d, the originally
concentrated mineral water becomes diluted by the fresh water
flowing down from above ; the carbonic acid gas, absorbed in
great quantity beneath, is gradually disengaged as the water
rises, and consequently the hydrostatic pressure is diminished,
and thus free carbonic acid gas is evolved at d with the acidu-
lous spring. It is clear, that the carbonic acid gas, which is
constantly disengaged from the rising water during its whole
course, not only moves on with the water on the surface of the
stratum h d, but fills all the intervals of the clefts in the whole
clay-slate rocks, so that the gas will be evolved wherever these
clefts are open at the surface. If these fissures open above the
bottom of the valley, and therefore are not filled with water, at
least not up to the opening, then the gas will escape from them
with a hissing noise. If, on the other hand, they open from
beneath the bottom of the valley, and are therefore filled with
water, then the gas will escape bubbling through the water,
and present entirely the appearance of a mineral spring.
If, lastly, these fissures be covered by alluvium, which, never-
theless, does not form an air-tight covering, then the gas will
escape silently from the ground, and such places are recognised
from the scanty vegetation which exists there. I know but
one of the first description of fissures in that district, which is
found close to the first mineral spring called Fehlenbor, in the
valley of Bw'gbrohl, between Tonnisstem and Buj-ghrohL Such
a fissure is found also in the Eifel^ in the Brudeldreis, as it is
called, not far from Bireshorn. Fissures filled with water,
from which gas is evolved, are tolerably numerous, as, for ex-
ample, in tlie valley of Burgbrohl, I formerly considered these

Volcanos and Earthquakes, 373

spots (which are constantly met with in the vicinity of the
brooks, and consist of little basins filled with water) to be
actual mineral springs. If, however, the basin be emptied out,
or the water drained off, it is at once perceived that no water
springs up, but that merely an escape of gas takes place. I
have had an opportunity of causing such gas-springs to be en-
closed, and found the disengagement of carbonic acid gas to
be extremely copious.* Fissures, covered by accumulated
eartli, are very frequently met with. If such a place presents
a slight excavation, in which the gas collects, suffocated animals,
as birds, mice, frogs, &c., are commonly found in it.

As springs run in the most different directions between the
surfaces of strata, and through the fissures of the strata, so al-
so do these disengaged gases. I have often had occasion to
cause excavations to be made, in places where a scanty vegeta-
tion rendered the disengagement of carbonic acid gas at some
depth probable. Fissures were often met with in the trass, out
of which rose abundant streams of this gas. Sometimes natu-
ral canals in the trass were found under a covering of SphdrO'
siderit, wliich could be pursued from ten to twenty feet in a
horizontal direction, or nearly so, and which doubtless were
prolonged still farther.-f*

If the carbonic acid gas arises from below with considerable
elasticity, and the cleft contracts very much from b to c, then
it may easily happen that the meteoric water may penetrate
but little below b. In this case, the column of water a b, will
be as it were supported by the column of gas,J and at the
point of contact, a constant absorption of the gas will be going
on. In this manner, probably, are those mineral springs form-
ed, which abound in carbonic acid gas, but contain very little
solid matter, and whose average temperature exceeds but little
that of the neighbouring wells. It must frequently be the
case, moreover, that many springs which rise from a greater

* Jahrb. der Chemie et Phys. t. hi. p. 129. (1029.)
t Neues Jahrbuch de Chem. et Phys. t. viii. p. 423, year 1833.
Ij: The rising and falling of the periodic sprirg of the salt- work at Ki»-
vjerij is doubtless a consequence of the elasticity of carbolic acid gas. See
^oggendorff's Ann. t. xl. p. 49c.

m^i

874 Prof. Bischof on the Natural History of

depth, and therefore are originally warm, become cooled by
mixture with cooler springs.

The warmest of the mineral springs in the environs of the
Laacher See exceed the mean temperature of the ground by
*7° to 10° Fahrenheit. What is worthy of remark is, that they
rise from the deepest spots of the valley, where, therefore, their
subterraneous channels are proportionably deepest under the
rock, and possess already a relatively higher temperature. On
pursuing the mineral springs up the valley, we find that their
temperature decreases in a somewhat regular^'ratio.*

The proportionably small number of clefts in the clay-
slate rocks may certainly account for the circumstance, that, in
the Laacher See, the EifeJ, and the Taunus, so few springs of
considerable high temperature occur, though the channels of
the carbonic acid gas lead down to such great depths, probably
to points where a red heat exists. Such warm springs may per-
haps owe their existence to the favourable circumstance of a
cleavage surface, which intersects the strata at an obtuse angle,
leading up from the cleft between the volcanic cone and the
clay-slate rock, and opening at a valley, as c d. Perhaps the
warm springs at Bertrich and Ems, which rise in deeply hol-
lowed valleys in clay-slate rocks, are thus produced.

We may also easily conceive the possibility of obtaining a
thermal spring by boring. A slight glance at the figure will
shew that a hole bored into a clay-slate rock in a valley, in the
vicinity of a volcanic cone, will probably give exit to a thermal
spring, if the borer reach the surface of a stratum or a slate
surface communicating with the cleft between the volcanic and
the clay-slate rock. A successful attempt of this kind was
actually made a few years ago, by boring into the clay-slate
rock at the foot of the basaltic hill, the Landshrone in the Ahr
valley, about three German miles north of the Laacher See,
when a copious mineral was obtained of the temperature of
58° F., affording considerable disengagement of carbonic acid
gas. Indications prognosticating a favourable result of this
undertaking were indeed present, inasmuch as a mineral spring

* So in the chain of Taw wms mountains, the warm springs rise deep in the
valley, the cold acidulous springs on the heights.

Volcanos and Earthquakes. S75

already existed at the distance of but a few steps from the
spot.*

Phenomena, perfectly resembling those which are observed
where volcanic masses have actually broken through, present
themselves very frequently. A cleavage, reaching to great
depths, may also be a consequence of a preceding elevation
and fracture of the component strata, without an actual break-
ing through having taken place. These phenomena are found
in formations of all ages. Thus Hoffmann-f- has pointed out,
in the north-west of Germany, some peculiar valleys which,
originally perfectly closed, are surrounded on all sides by a
precipitous escarpment, whose component strata incline from
the centre downwards in every direction. He has given to
these valleys the name of valleys of elevation. The most re-
markable of these, are those of Pyrmont, Member^, and Dri-
burg", where the well-known chalybeate springs rise, accompanied
by a considerable disengagement of carbonic acid gas. Ft/r-
mont and Meinberg lie precisely at those places where the di-
rections of the north-eastern system of mountains and of that of
the Rhine intersect. ,

Here, therefore, we find also a considerable disengagement
of carbonic acid gas ; yet no volcanic masses which have broken
through ; but only the secondary strata of shell limestone,
of keuper and variegated sandstone, raised up and fractured.
The mineral springs are of another kind, and the alkaline
carbonates are wanting, while sulphates and metallic chlorides

* A joint-stock company is also at this moment employed in boring into
clay-slate rock at Tlud-Ehrenhreitstein, near CoUentz, in order to procure ther-
mal springs. Since this spot lies scarcely two German miles distant from
the well-known hot springs of the temperature of 75° to 131° F. at Ems, and
at a lower level, and since an acidulous spring already exists there, the
possibility of the success of this undertaking is as little to be despaired of,
as a favourable result can be promised. Leop. von Buch's remarks on this
subject in Noggeraths Ausflug nach Bohmen. Bonn. 1838, p. 5. The in-
stance of the salt work of Nauenhebn, near Friedberg, where a salt-spring of
100° F. with immense disengagement of carbolic acid gas was obtained by
boring, proves that success is more likely to attend by boring into second-
ary formations, where a more frequent alternation of various strata exists.
At Hofgeisinar, near Ckt^sd, a new thermal spring with copious disengage-

lent of carbonic acid gas was also obtained by boring in May 1834.
t PoggendorJBf's Ann. t. xvii. p. 151.

376 Prof. Bischof on the Natural History of

supply their place. We may easily explain this by the ab-
sence of rocks containing alkalies ; for instance, basalt or any
other volcanic rocks. The clefts produced by these fractures
reach certainly to great depths ; carbonic acid gas may be
evolved from them, but its elasticity seems to prevent the pene-
tration of meteoric water. The mean temperature of th^'
mineral springs there, exceeds, therefore, but little that of the
place of their occurrence. This is especially the case with the
mineral springs at Meinberg; whose considerable annual varia-
tions of temperature prove that they take their origin very
near the surface. The considerable elasticity with which the
carbonic acid gas escapes, and which is greater than I have ob-
served at any place where gas is evolved, prevents, no doubt,
the deep penetration of meteoric water. Moreover, we may
remark, that the inclination of the strata, from the centre
downwards in every direction, carries the meteoric water away
from the seat of the evolution of the carbonic acid gas. Even
supposing, then, that the water could penetrate to the depth of
the channels of carbonic acid, it would not rise, owing to the
absence of the pressure of a column of water. The section of
the valley of elevation of Fyrmont, taken from Hoffmann's
work. Fig. 3. distinctly shews the inclination of the strata a &,

Fig. 3.

^^9 ^f^S^ ^^9 ^^5 from the centre downwards.

It is possible that the raising and fracture of the secondary
strata in such valleys of elevation, was the consequence of the
elevation of volcanic masses from beneath, which masses have
not appeared at the surface. Supposing this to be the case, we
can easily imagine that at such places mineral springs may be
produced which contain carbonates of alkalies, because the mete-
oric water only can penetrate to these masses. But the low tem-
perature of the acidulous springs in question, shews that me-
teoric water penetrates to \ery small depths only at these
places.

Volcanos and Earthquakes, 377

Valleys of elevation of the kind described seem to be of
tolerably frequent occurrence ; thermal springs and disengage-
ments of carbonic acid gas are not, however, always met with,
either for want of sufficient depth of the clefts, or for want of
materials which give rise to the disengagement of carbonic acid
gas. Instances of three of such valleys at the eastern end of
the basin of London^ are given by Buckland.* See also his
and Conybeare's-(- description of the structure of the country
al St Vincent's rocks ; and the example at Matlock long ago
pointed out by Whitehurst.J Many other instances of this
kind occur in Daubeny'*s report. || Stifft§ also has long ago
shewn, that the rocks in the neighbourhood of the mineral
springs of the Nassau territory manifest evident changes in the
direction and inclination of their strata, especially saddle-shaped
elevations, often accompanied with fractures.

Finally, dislocations or faults produced by elevations and in-
tersecting stratified rocks, may direct the subterranean course
of springs in a very different manner. Buckland^ has given
many instances of springs originating from causes of this
kind.

If we take a summary view of all that has been said on the
subject of thermal springs, we shall find it impossible to avoid
recognising a relation between elevations of Plutonic masses,
the upraising of Neptunian formations, and thermal springs.
Cause and effect have, however, been frequently confounded
here. Thermal and mineral springs are seldom, perhaps never,
the cause of those effects. Where, however, these effects are
observed, where, in consequence, the penetration of meteoric
water into the interior of our earth has been rendered possible^
and where natural hydraulic tubes have been formed by the
upraising of strata, there the phenomena of thermal and mineral
springs were the consequence.

We should transgress our limits, were we here to pursue the
subject of thermal springs in their chemical relations, since the

* Geological Transact sec. ser. vol. ii. part i. p. 119. t Ibid. vol. i.

X Theory of the Earth, 1786. II P. 66.

§ Rullmann Wiesbaden, &c. 1823, p. 103.

H Geology and Mineralogy, &c. London 1836. Vol. ii. p. 106 and HO.

VOL. XXVI. NO. LII, APRIL 1839. B b^

378 Prof. Bischof on the Natural History of

general aim of these remarks is to shew that their degree of
heat depends on the greater or less depth of their origin, con-
sequently wholly and solely on central heat. The following
remarks, however, upon their chemical constitution, may per-
haps not be entirely superfluous.

The chemical ingredients of those springs which take their
origin at the boundary between volcanic and Neptunian forma-
tions, are derived in some springs from the former, in others
from the latter formations, in others again from both. The
following conjecture is probable. If considerable quantities of
carbonate acid gas are disengaged from the interior, which are
absorbed under strong hydrostatic pressure by the water, and
thus act on the volcanic stone, decompositions ensue. The al-
kalies which are found in all stony masses of igneous origin, are
extracted by the carbonic acid, and taken up by the water as
carbonate of alkalies, and especially carbonate of soda. In
the same manner are formed the bicarbonates of lime, magnesia,
and of protoxide of iron. Metallic chlorides and sulphates may
perhaps be less frequently derived from volcanic matter, and
more so from the Neptunian formations. In this manner pro-
bably are formed the great number of springs, which rise in
the neighbourhood of basaltic hills.. Where there is no disen-
gagement of carbonic acid gas from the interior, no such mi-
neral springs are found ; at least we cannot assume that in this
case the volcanic rock contributes any thing essential to the
constituents of the springs. Thus, probably, neither in the
Pyrenees nor Alps do the springs take up any thing essential
from these rocks. The circumstance, that springs of y^ry va-
rious chemical composition arise in the vicinity of the granite
of different mountains, might here serve as an indirect proof.
At the same time, the nearly similar composition of the springs
occurring in the neighbourhood of the basalt cones, where car-
bonic acid gas is disengaged, however different may be the
Neptunian formations, is an argument in favour of these springs
deriving their ingredients principally from the basalt.

The organic matter found in such abundance in the sulphu-
reous springs of the Pyrenees (baregine, glairine, animal mat-
ter) proves, that their chemical constituents must be derived,
at least in part, from the Neptunian formations. Since no carbo-

Volcanos and Earthquakes, 379

nic acid escapes from the rocks there, the granite in] the interior
may, indeed, suffer but slight decompositions. The formation
of the sulphureous springs there, probably by the decomposition
of sulphates by organic matter, is certainly much favoured by
the high temperature of these springs ; and this again is a con-
sequence of the great depth, to which the clefts extend in the
strata, which are piled up one on another in considerable
masses, and partly raised up, with many strata-surfaces he-
tween them. The coincidence of various circumstances may
thus produce one class of thermal springs in preference to
another.

In the Alps, where, on account of the absence of escapes of
carbonic acid gas, decomposition of the granite and other vol-
canic rocks does not take place, and where even the Neptunian
formations contain few soluble substances, we find thermal
springs, which are scarcely any thing morejthan ordinary warm
water.

On the other hand, we see thermal springs issuing, to all ap-
pearance, from erupted masses, which springs contain ingre-
dients apparently peculiar to those which can be proved to issue
from Neptunian formations. This is, for instance, the case with
the salt-spring, which rises at Kreuznach out of porphyry. This
rock is but little fissured, and yet the high temperature of the
springs, 58° to 83°, indicates a deep origin. Since the por-
phyry has penetrated the variegated sandstone, the latter, and
also the shelly limestone, lie in close contact with the springs,
so that this volcanic rock has no other share in the formation of
these springs, than the production of deep clefts between itself
and the Neptunian formations, which have permitted meteoric
water to penetrate into the strata containing the salts. We
must not pass over one circumstance, which induces us to at-
tribute to these saline springs a totally distinct origin, viz., that
sulphate of lime, which otherwise so generally accompanies the
common salt, is here entirely absent, and that these springs are
remarkable for their abundance of bromine and iodine.

As escapes of steam (fumaroles) shew themselves in regions
(Tuscany for example) where hot masses have approached the
surface of the earth by volcanic activity, one might perhaps be
induced to expect evolutions of steam from clefts penetrating

Bb2

S80 Prof. Bischof on the Natural History of

deep into the interior. It must, however, be observed, that be-
tween these two cases a wide difference exists. In regions
where volcanic action still manifests itself, clefts can with ease
extend in masses which are of a boiling heat or even hotter.
Meteoric water penetrating these clefts will be converted into
vapour and exhaled. Were, however, such a phenomenon to
shew itself in regions where the increase of temperature follows
the progression, which we have found it to do in accessible
depths, then must such clefts extend perpendicularly to a depth
of about 8280 feet in our country. But are any rocks, even '
the unstratified masses, traversed by continuous clefts of so
great a depth ? In granite the prismatic separation is very
frequent. The columnar structure is most distinct in basalt,
aphanite, and all dense and homogeneous rocks. The columns
are sometimes traversed and disjointed by traverse clefts. The
surfaces of separation (Absonderungs Flachen) in the smaller
masses, always lie perpendicularly on the adjacent ones, as do
also the columns, when present. Let us assume that such a
jointed separation extends to the requisite depth, and that me-
teoric water penetrates so far, and then it will certainly rise
converted into steam ; when, however, it attains the higher
colder regions, it will become condensed again, and resume the
same course or circulation.

Since the volcanic masses, when thrown up, form, generally,
the greatest heights, we must look in them for the compressing
columns of water, which render the rising of the springs possi-
ble. The possibility of such a case is conceivable, when the
surface of the unstratified rock is inclined in one or more direc-
tions, and the columnar separations are jointed by transverse
clefts. It is, however, even then, possible only when the trans-
verse clefts have no continuation outwards, for in this case the
water will take a side course, and either issue on the slope of
the rocks as springs, or, if raised strata exist, it will take the
course designated in the preceding remarks. These two last
cases seem to be the most usual, as the circumstances above ex-
plained prove, viz., that thermal springs most frequently pre-
sent themselves between the unstratified and stratified rocks.
I have imagined the last case, in order to exhibit the possibility
of hot springs rising in the Alps, when water descends from

Volcanos and Earthquakes. 381

great heights to the interior of the rocks, flows through warm-
er strata of earth, and then makes its exit in the valleys. It
is clear that such springs merely flow from above downwards,
when the raised strata make their appearance externally, but
that they will, on the other hand, rise again, if the strata are
upraised in the form of a trough on the opposite side.

Phenomena lately observed, may perhaps present cases, where
the effect of the internal heat of the earth nearly approaches
the surface. Marcel de Serres,* for instance, describes a cave
near Montpelliej', situated in the Jura limestone, in which, at
depths of 135 and 150 feet, a constant temperature of 72o.5 F.
prevails, which exceeds by 10° the mean temperature of Mont-
pettier (6^°. 5). He shews that no accidental circumstance,
such as decompositions, the burning of tapers, or the respira-
tion of those who visit this cave, can be the cause of this phe-
nomenon ; but believes it is to be sought for in the central heat,
which rises through clefts and affects one point more, another
adjacent one less. Thus, at the distance of about 1200 feet
from this cave is found a cleft in the same formation, from
which issue watery vapours, whose temperature, 7S°.5 (that of
the external air being 52°-54j^.5), is nearly the same as of an
artesian well close in the vicinity of the cave (70°-72°). These
vapours, which probably rise from thermal springs existing
beneath, are constantly disengaged, and maintain a tempera-
ture of 73°.5, though in constant contact with the external air.
The cleft from which they issue, communicates with other
wider clefts, which expand into caves, into which the inhabi-
tants of the estate of Astier have already penetrated. The la-
bourers on this estate are in the habit of warming themselves
pretty frequently in the hole where these vapours are formed.
On examination, this vapour has all the purity of distilled
water. At an earlier period there existed, at the distance of
]50 to 180 feet N.E. of the grotto of Astier, another opening
from which an equally warm vapour was evolved, which could
be perceived at some distance off*. This opening has, however.

* Des Cavernes chaudes des environs de Montpellier in Annal. de Chim.
et de Phys. t. Ixv. p. 280.

382 Prof. Bischof on the Natural History of

been since filled up. This constant vaporization of water, in the
middle of the same rock in which the cave is found, shews pretty
evidently the cause of the warmth in the latter.

It is scarcely to be doubted, but that, on closer investigation,
the phenomenon of local heat in caves in the limestone rocks,
which are fissured to such great depths, would be found to be
of more frequent occurrence. The spring of the Orbe in the Jura
mountain, formerly mentioned, which is nothing more than the
discharge of the lakes situated 680 feet higher in the valley of
the JouXy proves, among others, to what a depth the clefts in
the limestone rocks descend.

The whole ridge of the chalk hills of the Teutohurger Wold
near Pader born, is fissured to depths exceeding 800 feet, so that,
on this whole ridge, either no springs at all, or but a few very
scanty ones, are met with, which probably owe their existence
to partial beds of marl in the chalk rocks. In three villages
which lie on this ridge, there is but one well 80 feet deep. On
account of this almost total want of water, these are called the
*^' Dry Villages." The cleavage continues in the valleys which
traverse these hills, consequently the brooks and rivers which
flow through them gradually sink and flow out of the open-
ings of these valleys only in the wet season of the year. At
the foot of these chalk hills on the other hand, where the fissured
limestone is covered by a stratum of marl, a very great num-
ber of copious springs issue, several of which form considerable
rivers, as the Lippe, Pader, Heder, &c., immediately after their
exit. The cleavage of the chalk rocks is doubtless continued
in the Quader Sandstein, which lies below and probably is li-
mited by the lias [grypMtenhalk) and variegated marl, which
follow immediately below the green sand, and which are re-
markable for their large strata of clay marl {thonmergel),
that are impermeable, unless broken or dislocated by ele-
vations. This whole chain of hills, then, from the clay-marl
strata to the level of the springs which issue on the western
declivity of the Teutohurger Wald, is, therefore, saturated
with jjwater like a sponge. Not merely geognostical reasons,
but also physical relations, furnish incontestible proofs of
the existence of these considerable subterraneous reservoirs of

Vokanos and Earthquakes. 383

water. For instance, while the water of the above-mentioned
sinking brooks and rivers penetrates into the interior of the
hills with the variable temperature of the seasons, the waters of
the numerous springs of Faderborti, whose mean temperature is
50°.6 F, and exceeds the mean temperature of the soil by about
1°.7, present already a uniform degree of heat. Thus, on the
21st ^ay 1834, I found the temperature of the Jlme at Bren-
ken, where considerable masses of the water of this river flow
down through the clefts of the chalk, to be 63"^, while the springs
at Geseke, at the distance of 22,000 feet, which doubtless re-
ceive their supply from this river, were of the temperature of
49° to 51°. The miller there, whose mill is turned by one of
these springs (what is called the Volmeder spring), told me he had
often opened the holes found on the banks of the Alme, and let
in as much water as would have been alone sufficient to turn
his mill, but that he never perceived the slightest increase of
the streams. This also proves the great extent of the subter-
raneous reservoir of water, whose discharges are not percepti-
bly increased by an addition of water. If, indeed, these addi-
tions are continued by continued wet weather, and the level
of the subterraneous reservoir rises, then, not only will those
springs become more copious, but water will also issue from
high-situated channels, which contained no water during the
dry season. Lastly, the same miller assured me that the
muddiness of his mill-streams by no means depended on that
of the Alme^ since they always become so after rain. Opi-
nions were, however, divided on this point, as other inhabit-
ants of Geseke maintained , that, within twelve or sixteen hours
after rain, the Alme became muddy, and the Volmeder springs
became so too, while this had no influence on the springs in the
town. Be this as it will, thus much is certain, that all the
springs there do not become muddy after rain, but that many
always remain clear, as the warmer among the Pader springs.
This circumstance is also a satisfactory proof of the great ex-
tent of the subterraneous reservoir, because, notwithstanding
the fact, that the sinking rivers and brooks, as well as the rain-
water and snow-water, which penetrate into the fissures of the
fissured rock, are all muddy in rainy weather, yet the warmer

384 Prof. Bischof on the Natural History of

springs, those consequently which rise from a greater depth, run
out clear.

I have instituted some experiments in order to ascertain
what must be the extent of a single mass of water, which re-
tains a uniform temperature, when a given quantity of water
is added to it, whose temperature varies with the variable tem-
perature of the rivers of our latitude, and when from it '^ dis-
charged an equal quantity of water, whose annual variations of
temperature are limited to those observed in the coldest of the
Pader springs.'^* The water-district (Wassergebiet) of these
springs is about 216 millions of square feet, and the quantity
of water which they afford in one minute 16,5J30 cubic feet, ac-
cording to measurements, as accurate as the nature of the thing
would admit. It was calculated, from these numerical data,
that a mass of water, 120 feet in depth, must be present in this
district where the springs rise, if all the water which sinks here
in half a year produce an alteration of temperature of 2°.25 F.,
presupposing that a mean difference of 22°. 5 exists between the
temperature of the water which sinks, and of that which lies
in the fissured rock. Since, however, the presupposition that all
the springs in Paderborn undergo this variation of tempera-
ture of 2°.25 in a half year, applies only to those whose average
temperature does not exceed 50°.6 F. ; while the warmer springs,
which are by far the more numerous, exhibit no variation of
temperature during the whole year ; the size of the subterra-
neous reservoir must be much vaster, if such considerable quan-
tities of water of a uniform temperature flow from it, while
the water, which sinks and is added to it, suffers variations of
temperature dependent on those of the atmosphere.

" It is really a remarkable fact to see so considerable a number of springs
rise in so small a compass as the lower part of the town of Paderborn^
Their number is said to amount to 130, several of which constantly appear
close together, often at the distance of but one or two paces, and imme-
diately form considerable brooks, which by their union form the Pader, so
large a river, that its different branches turn no less than fourteen undershot
water-wheels of the town situated near together. Almost equally large
masses of water, however, derive their sources from Lippspring, Kirchbor-
chen, and Upsprung, not to mention the many other springs which lie dis-
persed at the foot of that chain of hills.

Volcanos and Earthquakes. 385

Calculations of this kind can, from the nature of the subject,
give but approximations to the real size of that of which we
could otherwise form no estimate at all. The preceding cal-
culation shews, at least, that all the clefts and caverns in the
chalk rock of the Teutohurger Wald must be filled with water
from the level of the springs, down to some impermeable stra-
tum. How otherwise can we explain the fact, that consider-
able quantities of water of the varying temperature of the at-
mosphere constantly sink into the rock, and that as consider-
able quantities flow out at the slope of the rock, presenting a
uniform temperature, or at all events one which varies only
4°.5 Fahr. in a whole year. Since the conjecture is probable
that the lias and the variegated marl present the first entirely
impermeable strata, we may also conclude, that not only the
chalk formation, but also the green sand, which is equally fissur-
ed, are filled by the reservoir, and that its bottom is formed by
the above-mentioned impermeable strata. Lastly, the high tem-
perature of what are called the warm Pader springs {54P.B-^
61°.25 Fahr.) indicates also an origin from a greater depth,
if they do not flow in distinct channels, but come from warm
streams, which rise from the base of the reservoir.

The copious springs, which rise on the western declivity of
the Teutohurger Wald^ owe their abundance of water, even in
dry seasons, to these vast subterraneous reservoirs ; and what is
derived from these reservoirs, is abundantly replaced in the
rainy seasons, when nearly all the water collected in a district
so much fissured, penetrates into the interior.

These large masses of water, whose temperature exceeds, by
several degrees, the average one of the district under which
they are collected, and which bring so much the more heat to
their surface the deeper they penetrate, have doubtless the ef-
fect of warming the hills under which they exist. It is there-
fore perhaps a phenomenon of universal occurrence that all chalk
hills, which are much fissured, and into which brooks, rivers,
and most of the meteoric water sink, maintain a relatively higher
temperature. The Pader springs alone, however, shew how in-
exhaustible must be the sources which warm such vast masses
of water. These springs furnish in a year at least 8688 mil-
lions of cubic feet of water, whose average temperature exceeds

386 ]\Ir Russell on the Vibration of

by at least 6°.75 Fahr. the average temperature of the ground
at Paderborn, and this excess would melt a cube of ice, having a
side of 934 feet. This heat is irrevocably withdrawn from the
interior, and yet the thermal springs of Paderborn have sustain-
ed no diminution of heat from time immemorial.* Chemical
processes, which could there give rise to such inexhaustible
sources of heat in the youngest secondary formations, must be,
or have been, carried on to a great extent indeed !

Oji the Vibration of Suspension Bridges and other Structures ;
and the Means of preventing Injury from this Cause. By
John Scott Russell, M. A., F. H. S., and Vice-President
of the Society for the Encouragement of the Useful Arts
in Scotland, t

Since this paper was sent to press, my attention has been
directed, by Lieut.-Col. Blanchard, K. H., of the Royal Engi-
neers, to an account of the destruction of the third arch of the
chain pier at Brighton, inserted in the first volume of the Pro-
fessional Papers of the Corps of Royal Engineers, containing
observations made during the storm, and sketches of the ap-
pearance of the bridge on the spot, by my friend Lieut.-Col.
Reid, who has since distinguished himself so much by his
researches on storms, and who has now been so deservedly ap-
pointed to the governorship of Bermuda. This paper gives
such a perfect confirmation of the views I have taken of the
general nature of the vibrations that destroy suspension bridges
and other slender structures of a similar nature, as to shew
that the manner in which I have predicted that chain bridges
are likely to be injured, is the precise way in which this suspen-
sion arch was actually destroyed, and that the remedy I have
pointed out is the only one appropriate to the evil : indeed, so
precisely does my view of the matter correspond to the fact,
that Col. Reid's sketch of the Brighton arch, when in the

* By far the greater number of the remaining copious springs, which
rise on the western declivity of the Teutoburger W aid, are also thermal ones.
Some, for instance, in Lippspring attain a temperature of 54°. 5.
t Read before the Society on the 16th of Jan. 1839.

Suspension Bridges and other Structures, 887

act of giving way, is identical with my illustrative diagram,
Fig. .

It has, therefore, appeared to me, that I cannot give to the
reader a better conception of the nature of the evils I have
attempted to elucidate and remedy, than by presenting him
with Col. Reid's sketches of the Brighton arch in. the act of
giving way, and after it had fallen, along with his own de-
scription of the event.

Fig. 1, Plate I, is a sketch shewing the manner in which the
third span of the chain-pier at Brighton undulated, just before
it gave way in a storm, on the 29th November 1837.

Fig. 2, Plate I, is a sketch shewing the appearance of the
third span after it gave way.

" The same span of the Brighton chain-pier (the third from the shore),
has now twice given way in a storm. The first time it happened in a
dark nighty and the storm was accompanied by much thunder and light-
ning : the general opinion of those who do not inquire into the causes
of such matters was, that it was destroyed by^ lightning ; but the persons
employed about the pier, and whose business it was to repair it, were
satisfied that the first fracture was neither caused by lightning nor by the
waters, but by the wind.

" The fracture this year was similar to the former, and the cause evi-
dently the same. This time, it gave way half an hour after mid-day, on
the 30th of November 1836, and a great number of persons were there-
fore enabled to see it.

'' The upper one of the two sketches annexed, shews the greatest de-
gree of undulation it arrived at before the road- way broke ; and the under
one shews its state after it broke ; but the great chains from which the
road is suspended remained entire.

'* When this span became relieved from a portion of its load by the
road-way falling into the sea, its two piers went a little on one side, and
the curve of the chain became less, as in the sketch. The second and
fourth spans in these sketches, are drawn straight, merely to shew better
the degree of undulation of the third span. These also undulated greatly
during the storm, but not in the same degree as the third span. A move-
ment of the same kind in the road- way has always been sensibly felt by
persons walking on it on high winds ; but on the 29th of November
183G, the wind had almost the same violence as in a tropical hurricane,
since it unroofed houses and threw down trees. To those who were at
Brighton at the time, the effect of such a storm on the chain-pier was
matter of interest and great curiosity. For a considerable time, the un-
dulations of all the spans seemed nearly equal. The gale became a
storm about eleven o'clock in the forenoon, and by noon it blew very

388 Mr Russell on the Vibration of

hard. Up to this period many persons from curiosity went across the
first span, and a few were seen at the further end ; but soon after mid-
day the lateral oscillations of the third span increased to a degree to
make it doubtful whether the work could withstand the storm ; and soon
afterwards the oscillating motion across the road-way, seemed to the
eye to be lost in the undulating one, which in the third span was much
greater than in the other three ; the undulatory motion which was
along the length of the road is that which is shewn in the first sketch ;
but there was also an oscillating motion of the great chains across the
"work, though the one seemed to destroy the other, as they did not both
(at least as far as could be seen) take place in a marked manner at the
same time.

" At last the railing on the east side was seen to be breaking away,
felling into the sea; and immediately the undulations increased; and
when the railing on this side was nearly all gone, the undulations were
quite as great as represented in the drawing." — Lieut-Col. Reid, R, E.

The reader who studies the principles I have explained in
the following paper, will perceive that the remedies I have
proposed, are those by which such destructive vibrations would
have been rendered impossible.

My attention was directed to this subject, so important to
the arts, by having occasion, a few years ago, to erect a timber
scaffolding of considerable height, for experimental purposes,
in peculiar circumstances. There were many reasons which
rendered it proper to use very slender and very long pieces of
timber for this purpose, so as to come near to the utmost limits
that the structure would bear. Before it was removed a vio-
lent storm occurred, in which it suffered considerable damage
from the vibrations produced by the action of the wind ; and in
forming arrangements for remedying these injuries, and pre-
venting their recurrence, I was led to the examination of those
principles of vibration from which I have deduced the practi-
cal maxims that form the subject of this communication. After
detailing the circumstances which originally conducted me to
these conclusions, I shall explain the principles on which they
depend, and conclude the paper with some practical rules.
Although the whole subject is very extensive, reaching to all
the structures and mechanical arrangements in which vibration
is to be prevented, I have here applied it principally to suspen-
sion bridges, not only on account of their national and com-

Suspe7ision Bridges and other Structures. 389

niercial importance, but also because, in these very light and
slender structures, we are so near to the limit of possible strength,
that the mere addition of weight to the parts, instead of
strengthening, is certain to weaken them, by increasing the load
to be borne, and the momentum of the mass, and so increasing
equally the danger of oscillation instead of diminishing it ; and
therefore it is peculiarly necessary in this case to obtain the
greatest possible strength to resist injury, with the smallest
amount of weight. The means of doing this is, therefore, the
principal object of this paper.

The original structure ^ig- 3.

was of red pine scantling, 6
in. X 6 in., and about 80
feet high. Figure 3. will
illustrate its construction.
There are four beams cut
from a log, as vertical
supports at the corners ;
these being stayed in the
middle by cross bars, and
the whole diagonally fram-
ed for the purpose of sta-
bility and stiffness. A B G
D is one of the sides of the
framing, and the stays are
at mnop, the middle of
the structure ; and the
top of the structure was
fixed by ropes attached to
surrounding trees.

This structure was perfectly adequate to the temporary pur-
pose for which it was erected, and its extreme slenderness en-
abled me to watch the nature of its oscillations. The under
part of tlie structure was sheltered by trees and high banks,
while its upper part was exposed to the wind in every direction.
When the wind began to act on the top of the framing, it pro-
duced an oscillation between A and ?/?, as I have represented in
fig. 4, and not only there, but it propagated a simultaneous
and almost equal current of oscillation to the part B m below

Mr Russell on the Vibration of

Fig. 4.

A

Fig. 5. Fig. 6.

7'

Fig. 7.

A

Fig. 8.

390

the middle ; and in like
manner simultaneous oscil-
lations were propagated
through the whole struc-
ture with a continually in-
creasing amount, until they
at last injured it.

The method of cure
which I adopted, was sim-
ply to alter the place of the
cross bars at m, bringing
them down, as shewn at m\
Fig. 5, and this simple
change was attended with
remarkable results, inas-
much as the vibration was
■very greatly reduced, even
though a larger portion of
the upper division was thus left to the action of the wind with-
out transverse support.

I next proceeded to make experiments upon the effect of
altering the place of the support m. I placed it as in Fig. 6, at
m"\ one-third of the length from the bottom, and there were
now vibrations as at first of great violence, only with a less
range and with greater velocity, and it is most worthy of re-
mark, that the point .r, which was not fixed by any support,
nevertheless remained stationary in the same manner as if it
had been fixed.

The support being next placed at m"'\ as in Fig. 7, being one-
fourth part of the whole length of the beam from the bottom,
the oscillations took place, as shewn in the figure, in four divi-
sions, the points z/ and ti- at equal distances apart remaining
stationary. The oscillations were less extensive and more rapid
than formerly, but still of great force and duration.

Finally, it was ascertained that, by placing m the support at
such a point, that its distance from the fixed points A and B
bore to each other no simple proportion of length, the propa-
gation and increase of oscillations are entirely prevented. Fig. 8.

Philosophical Explanation, — It is easy to account for these

Suspension Bridges and other Structures, 391

phenomena on philosophical principles — the case is in close ana-
logy with the phenomena of vibration in a musical string. The
string of an ^olian harp, acted on by the wind, vibrates in
numerical divisions exactly like this beam, and in doing so, it
gives out the beautiful tones called natural harmonies ; and by
an intimate acquaintance with the principles of producing these
tones, some performers on stringed instruments have attained
celebrity. The laws of vibration of elastic cords, will explain
by analogy the vibrations of the framings alluded to.

If A and B represent the two ends of a string which is struck
or put in vibration, while it is prevented by a touch of the
finger from vibrating at r/i, it will divide itself into two equal
parts at w, each of which will sound an octave to the open note.
If the finger be placed at m"\ fig. 6, the string will divide
itself into three parts, and each will vibrate in the tone which is
called the fifth above the other. If, next, the finger be placed
at m""y fig. 7, the string will divide spontaneously into four
parts, and the note sounded by each part will be that which is
called the internal of a fourth from its predecessor. The next
step taking one-fifth of the length of the string would stop it
in five divisions, and the note produced would be that which
is called an interval of one-third.

Now, the remarkable circumstance worthy of great attention
in this inquiry is this, that, unless the vibrating body be fixed
by a stop at one of these simple numerical divisions, 2, 3, 4, 5,
it will either not vibrate at all, or through a very minute space
only, and will return to rest almost instantly after the dis-
turbing cause ceases to act, instead of continuing to perform
equal timed oscillations.

Application to Suspension Bridges. — This case is in strict
analogy with the case of the vibrations of a suspension bridge,
and shews us the means of counteracting and suppressing its
vibrations in the most efficient and simple manner.

Every one who has noticed the vibrations of a suspension
bridge in a gale of wind, must have observed that its oscilla-
tions are performed in a certain measured time, and are pro-
pagated from one part to another until the whole structure is in
^a state of equal timed vibration.

It is also matter of common observation, that any equal

392 Mr Russell on the Vibration of

timed force, like that of soldiers marching in ranks, is the
greatest trial to which such a bridge can be subjected. A sus-
pension bridge near Manchester was destroyed by this means,
and it has, therefore, been necessary for the curators of such
bridges, to order that soldiers, in crossing such bridges, shall
walk with unequal paces instead of the usual military march.

In observing the vibrations of a suspension bridge, it will
be noticed that it divides into nearly equal portions which
oscillate in nearly equal times — figure 9 will give an idea of this

Fig. 9.

vibration — when one-half of the bridge is falling the other is
rising, it remains nearly stationary in the middle vibrating, in
halves ; again it will be noticed at another time vibrating, in
three parts as in fig. 10, or in four parts as in fig. 11, and so on.

Fig. 10.

Now, in order to prevent these oscillations, it will be of no

Suspension Bridges and other Structures, 393

use to adopt the various methods of staying that have hitherto
been adopted ; it is of no use to carry a stay-chain to the mid-
dle of the roadway,fig. 12, nor even four stays as at 2, 3, and 4,

Fig. 12.

because it will vibrate exactly as at figs. 9 and 11, neither would
stays at 2 and 3, as in fig. 13, produce the effect, because the

Fig. 13.

bridge would still oscillate as in fig. 10.

Mr Brunei has proposed a method of preventing oscillation,
which, though ingenious, is expensive and heavy, and yet has
not the desired effect. He has proposed an inverted chain
below the bridge ; but, besides the disadvantages of great ex-
pense and weight, this still leaves the cause of oscillation un-
removed, for the whole will, in the manner already described,
perform isochronous oscillations.

It is obvious, therefore, that, unless the cause of the propa-
gation of continued and equal-timed oscillations throughout the
I structure be thoroughly understood and prevented, additional
weight or strength given to the parts, will merely have the ef-
fect of uselessly loading and weakening the whole.
The following is the plan on which alone the oscillations are
to be reduced to the smallest possible extent in the most cffec-
VOL. XXVI. NO. Lll. APRIL 1839.
i

c c

394 Mr Russell on the Vibration of

tual manner. Suppose that stays may be placed below the
bridge, as shewn in figures 1 2 and 13, we are to inquire how
they may be best arranged so as to stop the vibration which
the others do not. First, let us take one stay, and inquire how
it may be most advantageously placed.

Case (1.) One stay. Fig. 14. Let the span of the bridge be
divided into five equal parts. Then one stay to any one of these
points will be as effectual as five stays, in reducing the extent
of equal-timed oscillations. Also it may be thus placed, mul-

Fig. 14.

tiply the length of the bridge by itself, halve the product, and
extract the square root — the resulting number gives that dis-
tance of the stay from one end, which will most effectually pre-
vent the parts of the bridge from oscillating together.

Case (2.) Two stays. Let the first be fixed as in Fig. 14,
then divide the length of the bridge into seven equal parts, a

Fig. 15.

second stay to one of these parts will still farther reduce the
oscillations in the proportion of 5 : 35.

Case (3.) Four stays. Let the whole length of the bridge
be successively divided into 5, 7, 11, and 13 equal parts; then
let a pair of stays be fixed on each side, at one of each of these

Suspension Bridges and other Structures. 395

Fig. 16.

sets of divisions, and the oscillations will be less with the
four stays in figure 16, than with the four stays on the old
method, in the proportion of 4 to 5005, being nearly 1251 times
better than before.

Case (4.) Any number of stays. Let the whole length of
the bridge be divided into 5, 7, 11, 13, 17, 19, 23, 29, 31, 37,
41, 43, 47, 51, equal parts ; taking as many of these dividing
numbers as there are stays, the result will be, that the power of
resisting oscillation will be found by multiplying by each other
all of the dividing numbers used.

It is unnecessary to enter in this paper upon the practical
details which will immediately occur to the civil engineer, and
suggest themselves readily to the intelligent mechanical en-
gineer. The stays should be similar in construction to the
main chains of the bridge, l^^t much lighter, and each link
should be kept in the straight line by a suspending rod from
the chain, continued from the platform, so as both to keep the
stay in the best position for resisting oscillation, and to distri-
bute its weight more equally.

The same principles which apply to a single arch apply to a
series of arches, either in a wooden structure, or extensive
stone arches, or a chain pier like those at Brighton, and that of
Trinity in the immediate neighbourhood. The arches should
bear to each other the porportion of some of the numbers in
the series of dividers already given, so as to prevent the propa-
gation of oscillations from one to another.

Stays in platforms, viaducts, and all wooden structures, when
intended to prevent oscillations, should be placed at distances
not perfectly equal, but in the proportion of the series of num-
bers already given, and all structures intended to prevent oscil-
lation should be found on the same principle.

John Scott Russell.
21 Co AXES Crescent, IQth Jan. 1839.

cc2

S96

Meicorolomcal TahleS'

Abstract of Meteorological Observations for 1838, made at Applegarth Manse, Dumfries-
shire, Long. 3° 12' W., Lat. 66° 13' N. ; height above the sea ISO feet ; distance from thi
sea 10 miles ; rain-gauge 5 feet from the ground. Times of observation 9 a. m. and 9 p. m
Temperature of the mercury in the barometer reduced to 32° Fahr. and corrected to sea-
level. By the Rev. William Dunbar.

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29.690
29.530
29.521
29.540
29.836
29.705
29.733
29.044
29.804
29.613

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398

Meteorological Tables.

Lord Gray's Meteorological Tablejbr 1838.

Extracted from the Register kept at Kinfauns Castle, North Britain.
Lat. 56° 23' 30''._Above the level of the sea 150 feet.

1838.

Morning, i past 9.

Evening,

i past 8.

Mean

Temp, by

Six's

Depth

of Rain

in

No. of Days. 1

Mean lieight of

Mean height of

Rain

-

J

v.

Fair.

Barom.

Therm.

Barom.

Therm.

Snow.

January .

29.900

31.903

29.917

30.161

30.193

1.45

19

12

February .

29.620

28.214

29.624

26.900

27.785

.86

4

24

March . .

29.592

39.580

29.580

36.838

38.838

2.04

8

23

April . .
May . .

29.602

43.400

29.619

39.033

41.600

1.35

5

25

29.800

49.516

29.815

45.326

46.355

3.15

10

21

June . .

29.627

54.000

29.626

b2MQ

53.500

5.82

16

14

July . .

29.721

59.516

29.726

57.097

58.355

3.24

17

14

August .

29.600

58.484

29.^24

53.935

56.839

3.52

19

12

September

29.822

52.900

29.833

48.400

52.233

3.42

13

17

October

29.703

46.968

29.685

43.935

45.903

1.84

10

21

November

29.400

38.500

29.425

36.633

37.933

2.65

12

18

December

29.792

40.645

29.808

37.258

39.742

1.26

8

23

Average of\
the year /

29.682

45.302

29.690

42.348

44.106

30.60

141

224

ANNUAL RESULTS.

Barombter.
Observations.

Highest,
Lowest,

4th February,^

MORNING.

Wind.
^SE. 30.52

. 29th November, ^ SE. 27.95

Thirmometer.

Wind.

28th June, SW. Q^°

15th February,^^ NW. 6=

Highest, . 4th February,

Lowest, . 29th November, — SW. 27.90

Weather.

Fair,

R^in or Snow, .

Days.

224
141

365

10th July, SW. 67=

14th February,^ NW. 10^

Wind.
N. and NE.
E. and SE.
S. and SW.
W. and NW.

Times.

33

115
103
114

365
Extreme Cold and Heat by Six's Thermometer.

Coldest, . . 15th February, Wind NW. . . —2°

Hottest, . . 8th May and 14th July, Do. SW. . . 74°
Mean temperature for the year lu38, 44°.106

Results of Two Rain Gauges.

In lOOths

1. Centre of Kinfauns Garden, about 20 feet above the level of the sea, 30.60

2. Square Tower, Kinfauns Castle, 180 feet, 30.93

( 399 )

Quantity of Saline Matter in Deep and Surface Sea-Water, ob-
tained in Lat. 0° 33' N., and Long. 8" 16' E. ; also Result
of three experiments on the Temperature of the Sea at great
depths ; and state of the Barometer and Thermometer during
a gale of Wind off the Cape of Good Hope. Communicated
by Captain Robert Wauchope, R. N.

My Dear Siii, — Agreeable with your wish, I beg to send
you, for insertion in your valuable Journal, a copy of Mr
Kemp^s examination of deep and surface water, which I ob-
tained when in command of H. M. ship Thalia, in October
1836, in Lat. 0° 33' N., Long. 8^ 16' E. The deep sea water
was taken from the depth of 65S fathoms ; it was brought up
from that depth by means of an instrument I have frequently
made use of for this purpose, consisting of a series of cases, one
within the other, having valves opening up so as to allow the
water to pass through on descending, but which closes on
hauling the instrument up. The thermometer was enclosed
in a glass tube in the centre of it.

Temperature of surface water by Fahr. . . . 78|

Do. of water from the depth of 653 fathoms, 43

35f

During this experiment there was no current, and when all
the rope was veered out, it was nearly perpendicular, not being
distant from the ship more than six fathoms.

Mr Kemp writes : — " I have examined the two specimens
of sea-water marked ' deep and surface waters,' and find the
deep water to contain more saline matter than the surface wa-
ter, being about 4J per cent., the water at the surface having
about 3 per cent. It contains also sulphate and a small quan-
tity of carbonate of lime.

The surface water differs chemically from the deep water
only in having no sulphate or carbonate of lime in its consti-
tution :

Specific gravity of the deep water, . . =1.30
Do. of the surface, . . . = 1.23^

A trace of iodine and bromine was found in both.

400 Captain Wauchope o?i Sea-Water,

Along with this notice, I send the result of three other ex-
periments* of my own, for ascertaining the temperature of the
deep sea water. I send also the result of an experiment of the
same kind made by Captain Sabine, who was good enough to
favour me with an account of it ; it is hardly to be supposed
that no alteration took place in the temperature of the deep
water before getting it to the surface : from these experiments,
however, I do not think it improbable that, at some given
depth, the temperature of the sea may be found at 40° all over
the world.

I inclose also a journal of the thermometer and barometer
during a gale of wind off the Cape of Good Hope, with re-
marks made at the time, from which one is led to suppose that
these gales act in a spiral. The barometer was adjusted with
the Royal Society's standard, which is an important desidera-
tum, as it is not uncommon to find one marine barometer dif-
fering from another more than two-tenths of an inch. It would
be very desirable to have the range of the barometer for dif-
ferent latitudes, to enable the navigator to know when to ex-
pect bad weather. During the heaviest gale off the Cape of
Good Hope, I never saw it lower than 29.51 inches ; whereas,
on the coast of Great Britain, the mercury may fall half an
inch lower, without expectation of bad weather.

Soundings made to ascertain the Temperature of the Sea at great
Depths :

Date.

Lat.

Loug,

Depth

in

Fathoms.

Temp.

of
Surface.

Temp,
of Deep
Water.

Diff, of Temp,
of Deep and
Surface W.

Time taken
to haul in
the Line.

Aug. 1
1816. ]■

10».UN.29°.9W.

480

80°

51° 29°

35 minutes

!& }

3.26 S.

7 .39 E.

1010

73

42

31

1 h. 20 min.

mi J

3 .58 S.

1 .37W.

300

73

52

21

32 minutes

Oct. \

1830. ;

0 .33 N.

8.16E.

653

78|

43

35i

20 minutes

Nov.)
1822. i

20 .30 N.

83.30W.

1000

83

45.5

37.5

Thermometer inclosed in an iron-box screwed down on leather.
Capt. Sabine.

* For previous experiments, vide vol. iv. p. 161 of Memoirs of Wemerian
Natural History Society.

and Temperature of the Sea.

401

State of the Thermometer and Barometer during a Gale of Wind off the
Cape of Good Hope, on the 6th September 1835, in Lat. 26° 03' A'.,
Long. 13° 59' E. At noon. Cape Point bore E.SE. 219 miles.

Time.

Th.

Bar.

Wind,

Remarlis on the Weather, Ac.

8 A. M.

62

29.75

SE. SW.

Light winds, very variable, heavv rain darli cloud*.

10 A. M.

62

29.75

S.SW.SW.vbl.

Light airs to fresh breezes, do. do.

Noon

62

29.59

SW. vble.

Heavy rain, wind very light, heavy clouds.

IP.M.

63

29.58

N.N W.to calm

A heavy swell from N.NW., heavy rain, close-recfcd
topsails.

3 p. M.

63

29.54

NW. vble.

Nearly calm, a heavy swell getting up.

5 p. M.

63

29.54

NW.

Wind suddenly increased to u strong gale, very
squally, dry, warm.

6 p.m.

63

29.51

NW.

Strong gale, dry, wr. heavy elds., a good deal of sea.
At tliis time the quicksilver began to rise, or i-ather
to become convex.

7 p.m.

65

29.56

w.sw.

The barometer had risen 0.5 when the wind shifted
suddenly to the WJSW, with heavy rain, and
much sea.

Since the wind has come round to the SWn we ob-
serve the upper NW. clouds passing the moon
rapidly, whilst a dark tliin scud passes in the op-
posite direction below the NW, clouds.

8 p.m.

68

29.59

w.sw.

More moderate, a good deal of sea.

9 p. M.

64

29.63

•

Much more moderate, moon shines bright, fresh
gales, the lower SW. scud flying very fast past
the moon, Mhilst the upper clouds are pjissing
not quite so fast from the N W. ; during night.

moderate.

Ever faithfully yours.
To Professor Jamesok.

R. Wauchope.

Observations on Boots and Shoes, with reference to the Struc-
ture and Action of the Human Foot. By Mr James
DowiE, M. S. A. Communicated by the Society of
Arts.*

When we examine, even in a superficial manner, the struc-
ture of the human foot, and consider the objects and uses of
its complicated machinery, we cannot fail to observe, that the
action of its beautiful mechanism must be much impeded by
the artificial coverings which are generally applied to protect it
from external injury.

It will readily be admitted, that the best coverings for the
human foot, must be those which, while they protect it from

• Read before the Society of Arts, 15tli March 1839.

405! Mr Bowie's Observations on Boots and Shoes,

external injury, allow those motions which, its anatomical struc-
ture clearly shews, were intended by the Framer of our bodies
to take place.

In noticing the defects of the ordinary boots and shoes, I do
not intend to give a history of them, but take the liberty to refer
to a paper on the subject in the Saturday Magazine, 4th April
1835, and another in the Penny Magazine of May 5th, 12th,
and 19th, 1838, which bring down their history to the close of
the eighteenth century, presuming, as the author observes, that
" All are acquainted with the boots and shoes of the nineteenth
century." I intend, however, to submit a few remarks on these,
since many are not acquainted with all the different construc-
tions of the nineteenth century, and with one class in particular,
viz., the patent elastic boots and shoes, which it is proposed to
introduce to the notice of the Society, after adverting to some
of the defects of the ordinary kinds.

The defects which arise from ordinary leather not possessing
that degree of pliability and elasticity which is requisite to ad-
mit of the natural action of the foot, have led to the introduc-
tion of various substitutes.

When the foot is under the pressure of the body, it is elon-
gated. This principle of elongation seems to have been long
admitted, inasmuch as all boots and shoes have hitherto been
made a little longer than the foot of the wearer ; but the differ-
ence in the degree of extension in the feet of different indivi-
duals appears to have been, in some measure, overlooked, as it
rarely happened that allowance was made for this difference ;
and the result has been, that many persons have never obtained
shoes long enough for their feet, when thus extended, the
measurement being generally taken when the foot is not under
the pressure of the body. Another important consideration
arises, from the circumstances connected with the altered posi-
tions of the foot in walking. As the foot extends in length
from heel to toe, in proportion to the height of the arch, the
strength of the ligaments, and the weight it has to support, the
elongation has been found, by actual measurement, to vary
from a quarter of an inch to a whole inch.

In Fig, 1, Plate II., which was drawn from the foot relieved
from pressure, the sole is concave under the arch, the toe and heel

in reference to the Structure of the Human Foot. 403

being pointed towards the ground. Fig. 2, represents the foot,
nearly in the same position, !)ut bearing the weight of the body ;
the concave form is much less than in Fig. 1, being more in a
line with the heel and the toe, and the foot is elongated one-
third of an inch. Again, in Fig. 3, the sole has become convex,
the curve being nearly the reverse of that in Fig. 1, the radius
of the circle being better adapted for the act of rotation, than
the position of the foot when at rest, and the increase in length
is two-thirds of an inch.

As ordinary tanned leather soles are unyielding, a form has
been in use to accommodate the foot in walking, that form be-
ing nearly the same as the one shewn in Fig. 3, but it is not
suitable for the positions Figs, 1 and 2. A certain degree of
elongation of sole from heel to toe is obtained, but the stiffness
of the leather prevents the action of the levator muscles ; indeed,
a thick sole, made equal from heel to toe, cannot be used without
great fatigue to the wearer. Thickness has therefore been added
to that part of the sole immediately under the heel, which in
some degree relieves the levator muscles, so as to prevent their
due exercise, Fig. 4. The height of the heel, and elevation of
one end of the arch, is attended with other inconveniences.

Fig. 3 shews, that when the os calcis or heel-bone is raised,
the elastic arch is diminished, and a continuance of this position
soon gives the foot a flat form of sole. To prevent the arch from
flattening, when raised heels are used, that part of the boot im-
mediately under the arch is in general made much thicker
than the other portions of the sole, particularly in gentlemen's
boots. Fig. 4 : this was considered requisite to support the arch
when under the weight of the body : also, to admit of the boot
being taken off with any kind of boot-jack, or even without
one. This fashion of high heels, which is so generally in use
among the military, is by no means useful, for though it has
the apparent advantage of increasing the height of the wearer
an inch, or an inch and a half, and also of relieving the levator
muscles as before noticed, its disadvantages are very great ;
for, although an increase in the length of the leg, by having a
high-heeled boot, may appear to facilitate the operation of
walking, by furnishing a larger radius, yet it should not be
forgotten, that this artificial elongation of the leg is obtained

404 Mr Dowie'^s Observations on Boots and Shoes,

by a corresponding contraction of the muscles of the back part
of the leg. I'he full operation of the extensors is prevented,
and when this is much practised, the radius is diminished, and
the centre of gravity thrown forward, giving the person a ten-
dency to stoop, the knee-joint projecting out from its line, and
the muscles in the back of the leg becoming relaxed and con-
tracted ; and when the foot is changed suddenly from such
boots, into shoes with low heels, there is great danger of ruptur-
ing the tendons, which I have known to take place. The un-
equal pressure on the arch of the foot prevents the synovia
lubricating the articulating surfaces, thus impeding the free
motions of the joints of the toes, and preventing the wearer
from obtaining the advantage of the concave form of sole, so
requisite to give firmness of footing.

To the military man, and those who exercise the muscular
system when standing, this firmness of footing is essential, espe-
cially if it be loaded with additional weight.

The tendons and ligaments on the upper part of tlie arch are
frequently so compressed, that they become almost ossified :
this unequal pressure is produced by the altered positions of
the foot, Fig. 3. The muscles contract on the upper part,
while they are extended on the under part of the foot. As
this contraction in the length of the muscles increases their
thickness, and swells them outward, more space is required in
the upper part of the boot, than can be easily obtained, owing
to the stiffness of the sole. This stiffness prevents the change
of position in the foot, causing a vacant space between the sole
of the boot and the under part of the arch, while it allows less
space on the tipper part of the arch ; so that the foot is press-
ed against the upper leather of the boot, producing the injury
now mentioned.

The shape, as well as texture of the present style, of ladies'*
shoes and gentlemen's dress-shoes, are inconvenient, owing to
the shortness of the forepart of the shoe, which reaches no
higher on the foot than the ball of the great toe ; with such a
small hold on the foot, the shoe requires to be made tight across,
and nearly as short as the foot from heel to toe. If the length
necessary to permit the elongation of the foot were allowed, the
shoe would fall off at every step ; as, what the foot gains in

i7i reference to the Structure of the Human Foot. 405

length by its altered motiorts, it loses in thickness. The slip-
ping of the foot out of the shoe, is in part prevented, in the
one case, by the ribbons attached to the sides, and tied round
the ankle of the wearer, and, in the other, by a strap inside the
shoe, near the heel, through which the strap from the trowsers
passes, and keeps the shoe firm on the heel.

The wearing of such articles, however, is attended with
worse consequences then mere inconvenience ; the weight of
the body, being pressed on the delicate organization of the
foot, while its elastic properties are confined -in a covering of
a rigid texture, causes distortions and diseases of such a
troublesome and chronic nature, as to deprive the wearers of the
full use of their limbs.

In short, the stiff soles prevent that firmness of footing ne-
cessary for standing. They injure the elasticity of the arch, and
cause a jolt at every step as if walking on stilts; or, as if the
bones of the leg were perpendicular over the heel, they increase
the effort to raise the os calcis in walking, and prevent the pos-
sibility of running on the toes. In leaping, the value of the
number of the parts of the toes is lost, and the danger is in-
creased when falling on the whole sole.

In my own experience, I have known many ladies and gen-
tlemen who have had their feet injured from wearing shoes and
boots of the descriptions now referred to. Although such shoes
were long enough while the foot was not under pressure, yet,
when the weight of the body was placed on them, the joint of
the great toe was thrust back, and pressed on the metatarsus, —
the lubricating fluid was not supplied, the joint became in-
flamed, stiff, and enlarged, till at length suppuration com-
menced, as shewn in Fig. 5, from not adverting to the cause ;
the wearers endeavouring to relieve the enlargement by press-
ing the foot into the same small shoes, till they were impeded
in walking, and the joint became so distorted, as, in some cases,
to prevent them from using the joints of the toes, especially
those of the enlarged toe. With a view to avoid the pressure
on that p.'irt, they endeavoured to throw it on the other parts
of the foot, the heel, and smaller toes, thus causing themselves
to walk with pain and danger of falling, and with a rolling and
unsteady gait, and unfirm step, resembling those who have had

406 Mr Dowie's Observations on Boots and Shoes,

their toes frost-bitten. Such individuals always come down to
the ground with a sudden jolt at every step. This conforma-
tion of foot is apt to be produced at that period of life when
the foot is forming, or, as it is termed by anatomists, during
the " Moulding Process.'' This generally takes place between
the years of ten and sixteen. The bones of the foot, Fig. 6,
at this period arrive at their full growth ; indeed, they are larger
and softer than in after life ; the ligaments and muscles are soft
and feeble ; and, as the muscles act upon the bones in forming
the arch, if they are not called into active exercise, the arch
will become flat and the foot feeble. This is more common
among girls than boys, from the development of the body in-
ducing the ankles to incline inwards ; to prevent which, recourse
is sometimes had to steel supports to the foot and ankle, but as
these do not permit the natural action of the muscles, they pre-
vent the elevation of the arch.

It may not be out of place here to notice the fact, that when
the muscular system becomes relaxed by age, we find those in-
dividuals unable to lift their feet with ease, and obliged to drag
them along without calling the muscles into action ; at this
time of life we find the arch begin to flatten, and the feet not
unfrequently subject to swelling.

Instances have occurred, where, without the use of steel sup-
ports, but by the use of elastic boots, properly constructed, this
deformity has been prevented or entirely removed,* Although

* Sir Charles Bell remarks, " That the whole apparatus of bones and
joints being constituted in accurate relation to the muscular powers, it is
preservedjperfect by exercise; the tendons, the sheaths by which they are re-
strained, and the mucous bursus containing the lubricating fluid, can be seen
in perfection only, when the animal machinery has been kept in full actitity.
In inflammation, and pain, and necessary restraint, they become weak ; and
even confinement and want of exercise without disease, will produce im-
perfections. Exercise unfolds the muscular system, producing a full bold
outline of the limbs, at the same time that the joints are knit small and
clean. Look to the legs of a poor Irishman travelling to the harvest with
bare feet ; the thickness and roundness of the calf shew, that the foot and
toes are free to permit the exercise of the muscles of the leg. Look again
to the leg of our English peasant, whose foot and ankle are tightly laced in
a shoe with a wooden sole, and you will perceive from the manner in which
he lifts his legs, that the play of the ankle, foot, and toes, is lost, as much
as if he went on stilts, and therefore are his legs small and shapeless : In

in reference to the Structure of the Human Foot. 407

corns and distorted nails may not, in every case, be caused by
small shoes, yet there are more produced by this cause than by
any other.

During all the while the wearer has not what may be con-
sidered neat shoes, as the foot thrusts them out at the side en-
deavouring to find room for itself, thus losing the original
shape of the shoe, which in all cases should correspond as
nearly to that of the foot as circumstances will admit.

Many years ago, I was much impressed with the imperfec-
tions in the structure of the boots and shoes in general use.
After devoting much time and attention in endeavouring to
remedy their defects, I believe that I have at length succeed-
ed in attaining this object. This is effected by making those
parts of the boots or shoes immediately under, and on each
side of, the principal arch of the foot of an elastic material.
rig. 7. This material is composed of caoutchouc and animal
skin, so manufactured as to bestow on the fabric the elasticity
of the caoutchouc, while it retains the tenacity and durability
of leather. The introduction of this elastic substance allows
considerable changes to be made in the form of the boots and
shoes, and gives the wearers the free use of their feet and
ankle joints in walking to a much greater extent than any
hitherto in use.

The patent elastic boots and shoes possess the following ad-
vantages:— They are light, elastic, and durable, and admit of
being made of the shape and form of the foot when at rest ; while
their capacity to alter their figure admits of their adaptation to
the ever-varying motions of the foot. They may be made
tighter than the ordinary kind, yet no unequal pressure is
felt : indeed, support is given to the foot, and this is particu-
larly beneficial when there is any weakness of the parts.

They are rendered light by the absence of that weight of
rigid leather placed in the sole immediately under the arch of
the foot.

short, the natural exercise of the parts, whether they be active or passive,
is the stimuhis to tlie circulation through them, exercise being as necessary
to the perfect constitution of a bone as it is to the perfection of the muscu-
Jar power."

408 Mr Dowie's Observations on Boots and Shoes^

Their elasticity is obtained by the insertion of the elastic
material in the middle of the sole, and in the sides of the
upper part, in the form of gussets, Fig. 7. This elasticity per-
mits the foot to retain its concave form, so essential to firmness
in standing, Fig. 2. It allows the varying positions in walking
to be assumed, without checking the elastic motions of the foot,
with which the shoe is elongated when under pressure, as shewn
Fig. 2. And when the os calcis is raised by the levator muscles,
as shewn Fig. 3, no resistance is given, and the foot retains its
place in the boot or shoe, without motion backward and for-
ward^within it ; thus avoiding the friction which causes blister-
ing and inflammation of the heels and toes.

In running, the fore part only of the boot or shoe touches
the ground, whereby an increase of speed is obtained ; and in
leaping, the toes only may rest on the ground and not the
zahole sole, which is attended with much danger. In dancing,
when the foot is bent in the direction from toe to heel, the shoe
contracts in length in proportion as the foot does, and when the
sole of the foot extends, that of the shoe does so also.

As regards their durability, it may be observed, that as
there is no unequal strain on these boots and shoes, they wear
more equally ; the strain on the ordinary kind being in them
avoided, by the provision of the. elastic material in those places
requiring to yield, thus preventing the upper portion from
giving way before the sole has been worn. Owing to the foot
being planted in the same manner as if no covering were on
it, a larger surface of the heel comes in contact with the ground,
— the heel of the boot or shoe has therefore as it were a firmer
hold of the ground, while the wear is laid equally on the heel,
in place of on the outside corner, as is the case with the high-
heeled ones having the stiff waists. And, as the foot is per-
mitted to accommodate itself to the uneven surfaces of the
ground it has to tread upon, the wear on the sole part is more
equal, as the elastic portion in the waist allows the foot to roll
more easily on the balls of the toes, while the friction is much
diminished both on that j^art, and also at the point of the toe. J

In the stifl* boots and shoes this friction is very great, the
lieight of the heel and stiffness of sole causing the outside of

Mr Brown on the Mucilage of the Fuci, 409

the heel and points of the toes to be worn long before the mid-
dle of the sole, which, with the heel, are the two points that
sustain the weight of the body.

It is well known that a thin-soled boot or shoe of the ordinary
kind, will last longer in proportion to its thickness than a thick
one will. Stout boots of the patent kind, by their elasticity,
possess all the pliancy of a thin sole, while they retain all the
strength and thickness of the strongest kinds.

The advantages gained to the wearers of such articles must
be obvious by the preceding observations ; for the combination
of lightness, elasticity, and durability, will permit them to take
long and continued exercise without injuring their feet. To
the military man they must be of the greatest service, as he
is not only exposed to long and continued exercise, but is
frequently loaded with a burden in addition,* that renders it
extremely painful if the coverings for his feet have no sym-
pathy with the functions thereof, — besides, his general strength
will be more or less eflPective in proportion to the stability of
footing which he possesses.

That the patent elastic boots and shoes possess the advantages
now stated, is amply established by the test of experience.

Edinburgh, 57 Frederick Street, James Dowie.

On the Mucilage of the Fuci, with Remarhs on its application
to economical ends.\ By Mr Samuel Brown, junior, Had-
dington. J

In the autumn of last year (1836), I was requested by my
father to examine the mucilaginous matter of the common sea-

* When an infantry soldier is on the march, the weight of his clothing
and accoutrements, &c. is about sixty pounds.

+ Read before the Society for the Encouragement of the Useful Arts in
Scotland, 26th April 1837.

X Report of Committee on Mr Brottn^s paper, the Muc'dage of the Fuci. — The
Committee on Mr Brown's paper on the Mucilage of the Fuci, have to re-
port, that the subject discussed in the paper is one of the highest import-
ance, and well worthy the attention of the Society, which is deeply indebted
to Mr Brown for bringing it before their notice. At the same time, while

VOL. XXVI. NO. LII. APKIL 1839. D d

410 Mr Brown on the Mucilage of the Fuci.

ware, with the view of ascertaining to what useful ends it
might be applied. I did so, and the following pages contain
an account of the results of my experiments. It would have
afforded me much pleasure if these had been more exact and
extended ; but if they subserve the end of suggestions to such
as have better opportunities and greater fitness, I shall have
obtained a higher reward than they deserve.

Professor John says he found the Fucus vesiculosus to contain
of a red glairy matter and flesh-coloured extractive, with sul-
phate of soda and chloride of sodium, 40 pts. ; a peculiar acid ;
a greasy resin, 20 pts. ; sulphate of soda, with a little muriate,
60.3 ; sulphate of soda, with much sulphate of magnesia, and a
little phosphate of lime, 128.7 pts. ; traces of iroti and magnesia
and albumen qfthejiici, 780 pts. These parts are fractional of
1000. Gaultier Claubry also states, that, amongst other ingre-
dients, he found a great quantity of '■'' albumen of the fuci'' in
the vesiculosus. This name implicates an error, on the detec-
tion of which the rationale of what follows is dependent. Dr
Duncan junior, in his Dispensatory, hinted his suspicion of it,
and, in the case of the Fucus endivicefolius^ confirmed it. The
principle, which John and Claubry call albumen, possesses not
one of the properties of albumen. It is coagulated by none of
the agents which coagulate albumen ; nor, indeed, is it coagu-
lable at all. It is precipitated by none of the substances which
throw down albumen, and it falls with some which leave that
principle in solution.

I have seen it spoken of as of a gelatinous nature, but as it
is not thrown down by tannin, this is inconsistent.

they approve of the suggestions offered in the paper, yet they are of opinion
that Mr Brown has not adduced sufficient proofs that the decoction of the
fuci can be so easily freed of its peculiar taste as he states ; and that, even
if it were, by the processes mentioned, it would require to be proved tliat
they could be conducted so easily, and so economically, as to make it of
consequence to use the fuci for the purposes proposed.

They would therefore recommend the farther prosecution of the subject,
and hope that Mr Brown Avill be induced to undertake it.

Aw. FYrE, M. D., Convene);
James Hunter, M. D.
M. Ponton.
]Edinbuegh, 24«/t Majf 1837.

Mr Brown on the Mucilage of the Fucu 411

Its real characters are those of mucilage, procured from
marsh-mallow roots and the pericarp of lintseeds.

The acetate of lead, and the well-known precipitants of mu-
cilage, throw down a white curdy mass from a solution of the
principle in question.

More than this, I have ascertained that the following new
properties are common to the mucilaginous matters procured
from the fuci and the sources just referred to.

When to a solution of either mucilage, a little cyanide of
iron and potassium is added, before the dropping in of sulphate
of zinc, there falls a curdy compound of the cyanide of zinc
with the mucilage. In a similar manner other insoluble cyan-
ides may be thrown down with it.

By changing the circumstances, in a manner which will be
evident to the chemist, we may precipitate similar curdy com-
binations of mucilage with the insoluble chlorides and iodides.

If what is called hydro- sulphate of ammonia be mixed with
a solution of mucilage, whether obtained from the fuci or the
other sources, and there be added nitrate of silver, there is pre-
.cipitated a black compound of the mucilage with sulphur^t of
silver. A similar result may be predicated of all the insoluble
sulphurets. In fine, by a skilful adaptation of circumstances^
mucilage may be made to combine with all the insoluble bi-
elementary electro-positives, and this unusually general cha-
racter belongs to tangle-ware as well as marsh-mallow mucilage.
If other communities of feature be necessary for their identifi-
cation, I may add, that a solution of that from the fuci yields,
with borax, a jelly which, while drying spontaneously, con-
tracts with such force as to crush the glass vessel which con-
tains it, and that, by long boiling with sulphuric acid, it is
changed into a substance endowed with the qualities of gum-
arabic.

I may here remark, that there exist essential differences be-
tween gum-ai-abic and mucilage. A solution of gum-arabic
(which erroneously retains the name of mucilage in the Phar-
macopeias of the Colleges) quickly acidifies and moulds, whilst
that of mucilage never does so.

Professor John states that the Fucus vesictdoms contains

Dd2

412 Mr Brown on the Mucilage of the Fuci.

780 ill a thousand parts of this mucilage, or, as he styles it,
" albumen of the fuci." I think that this is an over-calcula-
tion. The error may have arisen from the fact, that, by long
boiling, the cellular tissue of these plants is changed into what
possesses at least this property of mucilage, that it is precipi-
tated by dinacetate of lead. From bleached Fucus sahnatiis, I
have procured, by infusion, almost exactly half its weight of the
principle in question. Some of the sea- wares contain more of
this principle than others.

To procure the mucilage in a pure unmixed condition, this
formula will be found adequate : — Bleach some of the Fucus
by exposure to the sun — bruise it — macerate a day or two in
often-changed, acidulated water. This dissolves out the sa-
line matters. Boil half an hour in an extremely attenuated
aqueous solution of sulphuric acid. The sulphuric acid, I
conceive, aids the disintegration of the tissue of the wares, and
thus promotes the escape of the principle in quest from its
cellular confines. Agitate the decoction with animal charcoal,
a little carbonate of baryta, and a little litharge. Filter and
evaporate over a water bath. After powdering the mass ob-
tained in this way and washing it with alcohol, in order to se-
parate adhering chlorides, &c., a pure mucilage is procured.
When long boiled with sulphuric acid this becomes similar to,
or rather identical with, gum arabic.

Before proceeding to the practical application proposed to
be made of these facts, it may be well to recapitulate them.

1^/, The common sea-wares contain great quantities of mu-
cilage. 2J, This mucilage is easily separable from the other
ingredients of the wares. Sd, A solution of mucilage does not
become stale or mouldy, ^th, By a very simple process it is
converted into gum arabic.

Mucilage is one of the most nutritive of all vegetable proxi-
mate elements, as is suggested by its so general and abundant
distribution. The fuci we have seen to be plentifully supplied
with it. Many of these sea-plants luxuriate in unrestrained
and unused abundance in all the rocky parts of our rocky
coast. In some parts of that coast in the winter of every year,
and everywhere during that part of some years, might not the '^

Mr Brown on the Muciioge of the Fuci. 413

precarious food of men and cattle be eked out from this source?
Already have these weeds yielded us much. To them we once
owed our soda, and chlorine, and iodine. Now that these are
procured more easily from another source, the kelp-making of
our coasters has been taken from them. Why not make avail
of the mucilaginous matter with which the indigenous growth
of our island, now under consideration, is so replete ? and thus
save one more natural product of Scotland from the obloquy of
iiselessness, create one more subject of industry for some of its
unwilling idlers, and erect one more internal defence against
the peradventure of famine.

Indeed, several of the fuci have been used as a means of su|>
port for both men and cattle. The Irish eat their carrageen,
and we our dulce; and the former of these, the specific name
of which is cndivice/blius, is now well known over the coun-
try by the name " Irish Moss,"" as a nourishing and easily di-
gested food for invalids. In some parts of the shore, tangle is
mixed with the food of the cattle. Among the Orkneys, I am
told they, of their own- accord, descend to the sea-side for the
purpose of satiating an appetite, the demands of which are too
scantily supplied by their bleak and barren pasture-grounds.
An imperious lust for food forces them to devour what, with
almost any alternative, they would reject with disgust. The
cause of this disgust seems to reside in the numerous saline
matters of the plants. By the simple removal of this a vast
source of nutriment will be recovered from waste, the feeding
of cattle generally be rendered less expensive, and our northern
countrymen have one other item added to their stinted means
of sustenance. This end may be rudely effected by merely
boiling well bruised ware in water acidulated by a mixture of
sulphuric and hydrochloric acids (oil of vitriol and spirit of
salt). The residue may be mixed up with bran or chipped
straw, or the refuse of linseed-oil making, or it may be given
alone. In both forms do swine eat this, and a mule to which
I presented it, seemed to devour it with pleasure.

If, however, cattle were to be fed from this source on an ex-
tended scale, the method in which the preparation should be
managed is this. Let the tangle- ware be bruised by some rude

414 Mr Brown on the Mucilage of the Fiici.

machine — macerate a day or two in water acidulated by
vitriol — wash well with cold water — boil some hours in three
or four times its own bulk of water — strain — evaporate the
decoction to a thickish ropy consistence — mix with bran (aut
cetera), and put up in cakes. These cakes, after being dried,
keep for any length of time, and may be given to cattle in the
same way as the linseed cakes: they may be broken and
mashed with warm water.

The decoction may be evaporated to dryness, and dissemi-
nated in the form of cakes of mucilage ; or it might be dis-
pensed from the manufactory as " dreg"" is from the distilleries.

I trust that this suggestion will prove useful when extended
by such as have the requisite opportunities of experimenting on
a large scale.

The next proposal I have to make is, that the mucilage of
the fuci should be extracted in a comparatively pure form, and,
after conversion by prolonged boiling with sulphuric acid, sub-
stituted in commerce for the imported gum arabic of the acacia
tree. If this were to be carried into effect, the formula to be
adopted would just be a simplification of that which I have
given for the preparation of the principle in an entirely pure
-condition. If a manufactory of such gum were established, the
refuse, the cellular structure of the plants, might be appro-
priated to the feeding of sundry domestic animals, and the ma-
ceration liquor reserved for the sake of its saline contents.
(See page 412.)

Gum procured in this way would serve all the purposes of
gum arabic, and, by reason of its cheapness, might be applied
to a host of others. How is it that gum is so little used as an
article of diet in this country, seeing its nutritious qualities are
so well attested by the fact, that the Moors of the Deserts sub-
sist on six ounces a-day for weeks together ? Why should so
many of our countrymen bear the signs of famine in their eyes,
and be continually exposed to temptation, to moral and political
defection, while treasures of such wholesome food lie scattered
in kind profusion on our shm-es ?

{ 415 )

On the Influence of Atmospheric Pressure on the Tidal Waters
of Cornwall and Devon.

While on the subject of the heights in this district above
the level of the sea, it may be useful to observe that those whose
attention has been directed to the subject of heights of land
above tidal seas are by no means agreed as to the time of tide
which would best afford a level whence to obtain them. In
4iiis district, the north and south coasts are under very different
conditions as to tidal levels at the time of high tide. On the
north, from the form of the Bristol Channel, the tide wave on
the flood is so driven into a gradually diminishing channel,
both as regards depth and breadth, that high water-mark at
Cape Cornwall is beneath the level of high water-mark at Chep-
stow and Bristol ; and consequently intermediate heights, if
calculated from high water at the two ends of the channel,
would not agree. On the south coast, from its oceanic charac-
ter, levels are probably more even at high water ; but a glance
at Mr Wheweli's valuable chart of the variable range of tides
round the British Islands, wiU shew that this coast forms a por-
tion of the general variations in the height of the tide observed
among these islands ; and it will be obvious, from the different
conditions of the tidal waters on the south and north coast of
the district under consideration, that heights taken from high
water on one coast would not coincide with those taken from
high water on the other.

It has been generally considered that low water is the best
time of tide to take as a level whence to calculate heights on land,
it being supposed that the sea is then more equally distributed
amid shoals and along shores than when driven over the for-
mer, or along the latter, by the force of a flood tide, or during
the run of the ebb ; and consequently heights on land, sur-
rounded by tidal seas, are generally computed from low water-
mark.

Of late, chiefly in consequence of the observations of Mr
Walker, Assistant-Master Attendant in her Ms^esty's Dock-
yard, Devonport, and of Captain Denham, R. N., much atten-
tion has been called to the subject of half tide as being the level

416 On the Influence of Atmospheric Pressure on he

of least variation on tidal coasts, inasmuch as in the same place
the high water of any tide rises as much above the line of half
tide as low water falls beneath it. It has therefore been sup-
posed that the half-tide levels along the coast would coincide
with each other, due precaution being taken not to include those
estuary tides amongthem, where the low water-mark on the sea
coast is often considerably under the low water-level in such
situations, the waters running out on the inclined surface of the
bottom, in the manner of a common inland river. The greater
portion of the Bristol Channel would probably be considered
merely as an estuary, the ebb running out in the manner of a
j-iver over its bottom.

In his researches on tides, Mr Whewell has noticed that the
mean heightife of the sea at Singapore and Plymouth are nearly
constant ; and we understand that, by tidal observations made
under his direction at the extremities of the line, levelled at the
expense of the British Association for the Advancement of
Science, between the English and Bristol Channels, it has been
ascertained that the level of mean tide at both ends of the line
is the same within a small fractional part of an inch.

Mr Walker, who has long devoted much time to tidal phe-
nomena, considering that half-tide levels on oceanic shores,
such as a large part of those of Cornwall and Devon may be
regarded, give the equilibrium level of the sea, proposes a simple
method* for readily obtaining it, which, whatever opinion may
be ascertained of the general value of half tide levels, affords
very considerable facility in ascertaining that level at any given
place. ^

Mr Walker has observed with respect to the influence of
the pressure of the atmosphere upon the tidal waters on the
shores of Cornwall and Devon, that a fall of one inch of the

* " Whcu the barometer stands at its mean annual height, and the air is
calm and still, set up a tide-pole (or select a rock) in some sheltered corner
on the coast. Mark upon it the high and low water-levels, and half-way
between these points will be found the mean level of the sea. Under the
above condition a single observation will give the mean level very nearly ;
but numerous observations are necessary when great accuracy is required.'*
— Wallzer's MSS. Mr Walker most obligingly communicated his notes to
us to be used in any way which might appear best calculated to promote the
progress of science.

Tidal Waters of Cornwall and Devon. 417

mercury in the barometer, corresponds with a rise of six-
teen inches in the level of the sea, more than would other-
wise happen at the same time, under the other general con-
ditions ; a rise in the barometer of one inch marking a cor-
responding fall in the sea-level of sixteen inches. This he
has found to be the usual rate of such alterations in level; but
very sudden changes in the pressure of the atmosphere are
accompanied by elevations and depressions equal to twenty
inches of sea-water for one inch of merdury in the barometer.
Regarding the whole pressure of the atmosphere over the globe
as a constant quantity, all local changes in its weight merely
transfer a part of the whole pressure from one place to another ;
and hence he concludes that the subjacent water only flows
into, or is displaced from, those areas, where, for the time, the
atmospheric pressure is either less or greater than its mean
state, in accordance with the laws which would govern the con-
ditions of two fluids situated in the manner of the atmosphere
and sea. We might account for the difference observed by Mr
Walker, in the amount of depression or elevation of sea-level
produced by sudden changes in atmospheric pressure, by con-
sidering that a sudden impulse given to the particles of water,
either by suddenly increased or diminished weight in the at-
mosphere, would cause a perpendicular rise or fall in the man-
ner of a wave beyond the height or depth strictly due to the
mere chanfre of weight itself.*

* A circumstance connected with this subject, of considerable practical
value, has been noticed by Mr Walker, during his long-continued observa-
tions. He has found that changes in the height of the water's surface, re-
sulting from changes in the pressure of the atmosphere, are often noticed
on a good tide-gauge, before the barometer gives notice of any change.
Perhaps something may be due, in these cases observed by Mr Walker, to
tlie friction of the mercury in the barometer-tube, as it is well known that,
in taking careful barometrical observations, it is necessary to tap the in-
strument frequently and carefully, to obtain the measure of the true weight
of the atmosphere at a given time and place. The practical value of the
observation is, however, not the less, be the cause of the phenomenon what
it may ; for if tide-gauges at important dock-yards shew that a sudden
change of level has taken place, indicative of suddenly-decreased atmo-
spheric weight, before the bai-ometer has given notice of the same change,
all that time which elapses between the notices given by the tide-gange
and barometer, is so much gained ; and those engaged with shipping know
the value of even a few minutes before the burst of an approaching hurricane.

418 On the hifluence of Atmospheric Pressure on the

As regards the influence of the winds on the mean level upon
the south coast of Cornwall and Devon, Mr Walker observes,
that east and west winds scarcely affect it, but that southerly
winds raise the sea above it from one to ten inches, and off-
shore winds depress the water beneath it as much, according to
their force. On the morning of the 29th November 1836,
when the velocity of the wind was estimated at about 100 feet
per second, the sea at Plymouth was raised three feet six and
a half inches above the mean level, the greatest height above
the equilibrium level he has seen. The hurricane began at
S.W., and the barometer was very low ; therefore this great
increase in height is due both to the wind and diminished at-
mospheric pressure. A gale of wind from the southward, a low
barometer, and a high spring -tide concurring, cause damage
and inundations on the southern coast of Cornwall and Devon.
From the form of the Bristol Channel, and the absence of a
free passage for the waters, such as exists at the Straits of
Dover, in the English Channel, westerly winds force up and
sustain a great body of water, thereby raising the sea above
the mean level several feet. It appears from an account of the
great storm of the 26th November 1703, that the tide flowed
over the top of Chepstow Bridge, inundating all the low lands
on both sides of the Severn, washing away farm-yards, drown-
ing cattle, &c. ; and it is worthy of remark, that the barometer
is recorded to have then fallen lower than had ever been pre-
viously noticed.

It will be obvious that, while in a hurricane such as that of
November 1836, noticed by Mr Walker, the level of the sea
was raised on the south coast of Cornwall and Devon ; it was
also depressed on the north coast of those counties ; so that
the difference in the sea-level on the two coasts thus caused,
would be the sum of the elevation and depression produced on
each coast respectively. It will also be obvious, from the form
of the Bristol Channel, that the sea-level on the two coasts will
not be the same with westerly winds, and the difference will be
in proportion to the force of such winds. With easterly winds
also, this level will be disturbed ; for, while such winds act as
an off-shore wind in the Bristol Channel, forcing the waters
outwards, on the south coasts of Devon and Cornwall there

Tidal Waters of Cornwall and Devon. 419

will be little or no effect produced from this cause (as proved
by the observations of Mr Walker), because there is a supply
of waters from the eastward. It would therefore appear that,
around the shores of the district under consideration, when the
winds which traverse it have considerable force, the levels which
would obtain in calms are considerably disturbed, and conse-
quently minor effects of the same kind are caused by less
powerful winds, according to their velocity. To obtain,
therefore, true heights in this district above the sea, which
should correspond above a level in both channels, supposing
such level to exist, calm weather is essential for accuracy. —
From a valuable " Report on the Geology of Cornwall., Devon,
and West Somerset^'' by H, T. de la Beche, just published in
1 vol. SvOf with numerous sections and map. Longman and
Company^ London.

Description of several New or Rare Plants which have lately
Flowered in the Neighbourhood of Edinburgh., chiejly in the
Royal Botanic Garden. By Dr Graham, Prof, of Eotany.

Leycesteria formosa. lO^A March 1839.

L. formosa, Wallkli in Roxb. Flor. Indica, Carey's edition, ii. 182. —
Decand. Prodr. iv. 338. — WaUicli^ Planjtae Asiaticae Rariores, tab. 120.
Description bhi'uh branching, bark brown and cracked; branches op-
posite, ascending, glabrous, the twigs of delicate sub-glaucous-green.
Leaves (4^ inches long, 3^ broad) petioled, broadly ovato-cordate, incise-
lobate, smaller and more entire upwards, acuminate, veined, above of
the same colour as the twigs and glabrous, below paler and slightly
pubescent. J^etioles much shorter than the leaves, generally red, chan-
nelled above, stem clasping. Floirers in verticillate, bracteate, cemuous
spikes, terminal or in the axils of the upper leaves. BracUce large, cor-
dato-ovate, acuminate, red-purple, veined, somewhat hairy. Ccdyx per-
sisting, superior, its throat much contracted, and with that portion
which is dilated over the adhering germen scattered with purjile glan-
dular hairs ; limb 5-partite, segments very unequal, subulate, glandulosc-
pilose. Corolla (9 lines long, 7 a(fross the expanded limb) white, funnel-
shaped, with a small globular dilatation at its base, where it is inserted
into the base of the calyx, throat glabrous, its limb 6-partite, lobes
ovate, blunt, spreading ; nectariferous (/lands, 5 at the base of the tube.
Stame/ts 5, as long as tlie corolla, inserted into it, and adliering as
far as the throat, where they alternate with yellow streaks, below they
alternate with the nectaries ; filaments glabrous, filiform ; anthers ver-
satile, bilocular, bursting along the face ; pollen cream-coloured, gra-
nules small, globular. Pistil longer than the flower ; stigma capitate,
obscurely and unequally lobed ; style filiform, glabrous, articulated at
the base ; germen 5-locular ; ovules very numerous, pendulous from
central receptacles.
This plant was sent to the Botanic Garden, Edinburgh, from the London
Horticultural Society, in 1837, and flowered pretty freelj in July 1838,

420 Dr Graham's List of Rare Plants.

in moderate heat. The plant is a native of the Himalaya mountains,
and is handsome ; but the flowers are not very conspicuous, and the
bractea} are not deeply coloured when cultivated under glass. It is
probable that the incised state of the leaves also arises from cultiva-
tion ; for this is not mentioned in the description of native specimens
nor figured by Wallich.

Malva Creeana.

M. Creeana, fruticosa ; ramis sub-erectis ; foliis trilobatis, incisis, sub-
iindulatis, deltoideo-ovatis, stellato-liispidis, basi integerrimis ; flori-
bus solitariis, axillaribus ; petalis obcordatis, subcrenatis ; peduncu-
lis petiole brevioribus ; involucri foliolis filiformibus.

Malva Creeana, Hort — Grah. in Bot. Mag. 3698.

Description. — Stem shrubby, branched ; branches erect, closely covered
with harsh stellate hairs. Leaves petiolate ; petioles somewhat flattened
above, covered like the stem with similar hairs ; lamina rather longer
than the petiole, deltoideo-ovate, blunt, somewhat undulate, green and
sparsely covered with stellate pubescence above, white and more close-
ly covered with similar pubescence below, the upper leaves trilobate,
with the central lobe elongated, the lower less deeply cut into lobes,
but all coarsely and unequally incised, the segments blunt and reflect-
ed at their apices ; stipules filamentoso-subulate. Flowers axillary, so-
litary, on peduncles shorter than the petioles. Involucre of 3 filiform
leaves. Calyx longer than the involucre, deeply 5-cleft, pubescent on
the outside, subglabrous and shining within. Corolla of uniform rose-
colour, cup-shaped ; petals obcordate, and slightly crenate, glabrous
except at their insertion, where they are ciliated. Staminiferous column
hairy. Fistil equal in length to the stamens, rather shorter than the
petals; styles about 15, combined to about the middle ; germ en hairy.

This, though a small flowered, is an extremely pretty species, and very
deserving of cultivation in the greenhouse, where it flowers freely in
June and July. We received it at the Edinburgh Botanic Garden in
1837, from Mr Pince, nurseryman, Exeter ; but I know nothing of its
history, or of the country from whence it was imported. In the ar-
rangement of the species, it seems to me it should be placed near to
Mcdva ditaricata.

Pavonia Schrankii.

P. Schrankii ; inermis ; foliis subcordato-ovatis, acuminatis, intequaliter
serratis, utrinque stellato-tomentosis ; pedunculis 1-floris; involucris
calyce brevioribus, 5-partitis ; carpellis inermibus.

Pavonia Schrankii, Sprengel, Syst. Veget. iii. 98. — Grah. in Bot. Mag.

3692.
Lebretonia coccinea, ScTirank. PI. rar. h. mon. t. 90. — Fecand. Prodr. i.

446.

Description. — Shrub erect ; branches erect, and, as well as the whole
plant, except the corolla and parts within it, densely covered with
coarse, harsh, reflected, yellowish hairs, which are distinctly stellate on
both sides of the leaves. Leaves (3| inches long, \\-2 inches broad)
scattered, spreading wide, petiolate, ovate, subcordate at the base,
acuminate, strongly veined and wrinkled, darker above than below
where the midrib and veins are very prominent, coarsely and unequal-
ly serrated; petioles about l-3d of the length of the leaves. Stipuks
(half an inch long) slender, subulate, erect. Feduncles solitary, axil-
lary, reaching nearly to the middle of the leaf, single flowered. Invo-
lucre 5-partite ; segments ovate, valvate, and prominent in their edges
near the base, 5-nerved, with reticulated veins, wrinkled. Calyx longer
than the involucre, 6-partite ; segments similar to those of the invo-

Dr Graham's List of' Rare Plants. 421

lucre, but rather less coarse, with the marginal nerves less conspicuous,
at first erect, afterwards folded over the gennen. CoroUa (about 1$
inch long, 2 inches across when fully expanded) pentupetalous, orange-
coloured, yellow at the base ; petals imbricated and convolute, dola-
briform, many nerved, slightlyrtomentous, deliquescent in decaying.
Stamens indefinite, raonadelphous, inserted into the base of the petals,
and uniting these to each other; united filaments sliglitly tomentous, gi-a-
dually smoother upwards, free portion glabrous ; antlieis kidney-shaped,
unilocular, opening alo^g tlie vertex, attached loosely in the sinus to
the filament. Styles 10, cohering for above l-3d of their length, gla-
brous, each terminated by a small pencil-shaped crimson-coloured stig-
ma. Gennen oblong, wrinkled, green, of five verticillato lobes, each
containing a single oblong ovule, compressed on its inner side, and
there attached near its base to a central placenta. Cai-pds d&rk brown,
much wrinkled, subglabrous, glabrous and nearly white within, where
they seem evidently to be bivalvular, but are not, I think, dehiscent.
Seeds kidney-shaped, pale brown, glabrous except along the back, where
there are a few, and at either extremity, where there is a tuft of yel-
lowish hairs.

We received this plant from the Botanic Garden, Berlin, in 1836. It
flowered freely in the stove at the Botanic Garden, Edinburgh, in July
1837 ; but though its blossoms arc of considerable size, and not destitute
of beauty, the plant will probably never be a favourite in cultivation,
because its flowers are only expanded during the forenoon, and the
shrub is coarse and in no degree attractive. It is a native of Brazil.

Sprengel unites Lebretonia to Pavonia^ and Decandolle questions the pro-
priety of considering them distinct. The only part of the definition
which seems to me to justify the separation is the reported dehiscence
of the carpels, which 1 have not found to take place.

Pimelea hispida.

P. hispida ; involucris tetraphyllis : foliolis ovatis margine simplici in-
tus subsericeis capituli dimidio brevioribus, perianthii tube dimidio
iuferiore hispido, foliis lanceolatis linearibusve. — Br.
Pimelea hispida, — Br. Prodr. 3G0. — Eocm. et Schult. i. 273. — Spreug.
Syst. i. 92.
Description. — Skmb erect, slender, much branched; branches erect,
glabrous; bark yellowish-brown. Leaves (half an incli long, 2 lines
broad) opposite, light green, linear-lanceolate, or narrow ovato-lanceo-
late, slightly folded forward along the middle rib, which is conspicu-
ous, but without any lateral veins. Flowers capitate, surrounded by a
tetraphyllous involucre, of which the leaflets are cordato-ovate, concave
within, keeled on the back, and with an obscure lateral nerve on each
side, the two outer the narrowest, the others slightly silky on the in-
side. Perianth much longer than the involucre, red in the lower,
white on the upper half; tube covered on the outside with spreading
hairs, which are fewer, coarser, and much longer on the back of the
limb ; limb spreading, segments elliptical. Stamens deflected, white.
Stiijma small, capitate ; stijle exserted, glabrous, inserted below the apex
of the ovate, green, glabrous gennen.
We received this plant from Mr Low of Clapton in 1836. It flowered
freely with the usual treatment of greenhouse plants, but the flowers
are not of very long duration.

Pimelea intermedia, Hort.

P. intermedia ; foliis oppositis, glaberrimis, flor^libus ovatis acutis ca-
pitulo multifloro brevioribus, ramis lineari-lanceolatis ; raiuis gla-
berrimis, gracillimis, strictis ; calycibus toraentoso-villosis.
Description.— iS'ArH6, slender, erect, with loug straight almost filiform
branches, which are covered with brownish-yellow, glabrous, cracked

4S2 Dr Graham's List of Rare Plants.

bark. Leaves (| of an inch long, about 2 lines broad), glaucous, glabrous
on both sides, with a distinct middle rib, but no conspicuous veins,
linear lanceolate, inclining to spathulate on the branches, becoming
ovate and shorter towards the capitulum. Capitulum terminal, many-
flowered. Floicers white, longer than the floral leaves. Perianth sur-
rounded at its base with long erect hairs, tomentous on the outside,
striated, dilated over the germen, and diaphanous between the striso at
this part ; segments of the limb subequal, elliptical, with slightly invo-
lute edges. Stamens at first erect, afterwards reflected upon the limb,
and shorter than it ; anthers oblong, pollen bright orange. Germen
oblong, pale-green, glabrous ; style filiform, glabrous, longer than the
perianth ; stigma minute, capitate, bearded.

This very distinct and very pretty species we received at the Botanic
Garden, Edinburgh, from M, Makoy at Liege, in spring 1837. It
flowered very freely in March 1838.

In the arrangement of the species it should be placed in the section in
which the floral leaves and those of the branches are subsimilar, and
should stand next to P. sylxestris.

Statice puberula.

S. puberula; foliis obovatis obtusis, planis, raucronatis, integerrimis,
longe petiolatis, utrinque stellato-pubescentibus ; pedunculo bi-alato,
sparse stellato-pubescente, dichotome corymboso, ramis ultimis erec-
tis, triquetris ; calycibus obtusis, crenatis.

Statice puberula, Webb. — Bot, Reg. 1450.

Description. — Stem short and branching. Leaves obovate, flat, with a
slender recurved mucro, a prominent middle rib, and a few obscure
veins, stellato-pubescent and glaucous on both sides, attenuated into a
long petiole. Fedunde erect, round at the base, above compressed, twice
or thrice dichotomously corymbose, branches with two wings, the
subdivisions near the top secund and erect, and t'he ultimate branches
3-quetrous. Bractece reddish, pubescent, sheathing, blunt. Calyx twice
as long as the bractese, blunt, crenate, purple. Corolla white, funnel-
shaped, claws long, laminoe obcordate. Stamens about as long as the
corolla. Styles yevy slender. Germen green, glabrous.

This plant flowers freely in the greenhouse at the Botanic Garden, Edin-
burgh, and is ornamental, both when the white corollas are expanded,
and after they have fallen, when the purple calyces remain as its only
ornament. Professor Lindley notices a resemblance between this and
S. furfuracea of Lagasca. I do not recollect to have seen S. pectinata.
Ait., but, judging from the description, I have a doubt whether it be
different from our plant, which, as well as it, is from one of the Canary
Islands. The figure in Bot. Reg. has far more acute leaves than the
plant ever acquired with us.

Proceedings of the Royal Society of Edinburgh.

1838, December 3. — Lord Gheenock, in the Chair. The
following communication was read :

Discussion of one Year's Observations of Thermometers sunk
to different Depths in different localities in the neigh-
bourhood of Edinburgh. By Professor Forbes.

These observations were made, at Professor Forbes's suggestion,

Proceedings of' the Royal Society, 423

at the expense of the British Association. They are still continued,
and the present notice contains only a first approximation to the
solution of the problems which th^y are intended to give.

The chief aim of the experiments is to ascertain the progress of
Solar Heat in the Crust of the Globe, and has no immediate refer-
ence to the question of central heat ; the depth to which the expe-
riments extend being inadequate to aiford decisive results on that
head.

The experiments differ in their object from any hitherto made,
from having an especial regard to the structure of the soil and the
conducting power for heat of different geological formations. With
this view three series of thermometers were constructed by Mr
Adie, under Mr Forbes's directions, each nearly of the same length
and range, and these were sunk in holes prepared for them to pre-
cisely similar depths, (1.) in the Trap Tufa of the Calton Hill, with-
in the Observatory grounds ; (2.) in the homogeneous bed of Sand
at the Experimental Garden ; and (3.) in the compact Coal Forma-
tion Sandstone of Craigleith Quarry, all in the immediate neigh-
bourhood of Edinburgh, and within a radius of about a mile. With
a view to render these observations more immediately comparable
with those made at Paris and Brussels, the extreme depth was the
same, or the lowest thermometer had its bulb at the distance of
24 French feet (= 25.6 English) below the surface, and the others
were placed at each station at depths of 12, 6, and 3 French feet.*

The tube which connected the bulb with the reading part above
ground was made capillary, so as to contain as little liquid (alcohol)
as possible. Notwithstanding, all the observations have been ri-
gorously corrected for the inequality of temperature of their stems,
and likewise for the expansion of the liquid above ground. The
observations were commenced in February 1837, and have been
made once every week since. After being corrected they were
projected in the form of Curves : and the general consistency of
these with one another, and the peculiarities proper to each station,
are such as to give considerable confidence even in the first ap-
proximation, which extends from February 1837 to February 1838.
I. The general form of the curves at all the stations correspond-

* At the Observatory a thermo-electric pair of iron and copper wires
was sunk along with the deepest thermometer, with a view to test the ap-
plicability of M. Peltier's apparatus to this object. Several observations
closely agreeing with the thermometer have thus been made.

424} Proceedings of the Royal Society,

ing to different depths, agrees perfectly with what has hitherto been
observed under similar circumstances. As we descend, the curve
becomes more even, and flatter, the range rapidly diminishing, and
the epochs of minimum, mean, and maximum temperature occur
later.

II. The mean temperature of the soil appears to increase as we
descend (this has been observed at Brussels and elsewhere). At
the Experimental Garden the mean annual temperature is, at 3 feet
(French), 45°.54Fahr.; at 6 feet, 46^.70; at 12 feet, 46°.90 ; at
24 feet, 47°.28. The Craigleith observations are ambiguous in this
respect.

III. The annual ranges at the three stations and at the different
depths, are the following :

3 Feet. 6 Feet.

Observatory. Garden. Craigleith. Observatory. Garden. Craigleith.

Fahrenheit, 18°.95 19°.65 17°.25 ir.9 14°.95 13°.9

Centigrade, 10 .53 11 .23 9 .58 6 .61 8 .30 7 .72

12 Feet. 24 Feet.

Observatory. Garden. Craigleith. Observatory. Garden. Craigleith.
Fahrenheit, 5°.5 7°.55 9°.4 I ".45 2M 4°.l

Centigrade, 3 .05 4 .19 5 .22 0 .80 1 .16 2 .28

Now it is known by theory that the range ought to diminish in
geometrical progression as the depths increase arithmetically ; and
accordingly these results may be very closely represented by loga-
rithmic curves, having different Moduli at each station, depending
on the nature of the soil. If A denote the range in Centigrade
degrees at a depth jo, and A and B two constants, we have
Log. A^ = A + Bp

/specific heat
And B depends upon ^/ conductivity o^ the soil. Now this con-

stant B is found to have the following negative values ; *

Observatory —0.0547 ; Garden — 0.0440 ; Craigleith — 0.0317.

Consequently the conducting power of the strata is in the order
just written, the first being the lowest, the last the greatest (sup-

* In order to render the results directly comparable with those in M.
Quetelet's excellent paper in the Brussels Transactions, the French foot
and Centigi-ade degree are employed as unities.

Proceedings of the Royal Society, 425

posing the difference of specific heat immaterial). By extending
the Logarithmic curve, the depth at which the range has any
amount maybe found.* Thus the range will be reduced to yjj^ of
a Centigrade degree, or may be reckoned insensible, at the follow-
ing depths : —
Observatory, 58 feet ; Experimental Garden, 72 feet ; Craigleith, 97 feet.

Now it is remarkable that the above variations in the value of B
exceed those contained in M. Quetelet's table, which includes all
the observations made in different parts of Europe ; shewing that
the increase of the value of B with the Latitude, which was thought
to have been observed (Quetelet, Mhnoire sur les Variations Diurnes
et Annuelles de la Temperature Terrestre^ p. 61), was quite acciden-
tal ; and that the value of B must depend solely on the constitution
of the soil in which the experiments are conducted.

IV. The epochs of the winter minimum of 1837 are ill deter-
mined for the upper thermometers, owing to the great irregularity
of the winter curve, and also because the observations were com-
menced too late to obtain them correctly. The epochs of maxi-
mum temperature give, however, a complete confirmation of theory
and of the preceding deductions. We find that, with a single ex-
ception (the shortest thermometer at Craigleith), and that excep-
tion is doubtful, all the thermometers at Craigleith attained their
maximum first, then those at the Experimental Garden, and lastly,
at the Observatory, as the following table shews : —

Maximum at

3 Feet. 6 Feet. 12 Feet. 24 Feet.

Observatory, August 6. September 2. October 1 7. January 8.

Exper. Gar. July 31. August 24. October 7- December 30.

Craigleith, August 5. August 19. September 11. November 11.

We also find, as theory assigns, the retardation of the maximum
increases arithmetically with the depth. So that, if we project
these observations and cause an interpolating straight line to pass
through the points for each station, we find that the progress of heat
downwards is.

At the Observatory, 1 foot in 7-5 days.

Experimental Garden, 7-1 ...

Craigleith Quarry, 4.9 ...

giving the same order of conducting power as before.

The bearing of these experiments on geological theories, and es-
pecially on the movement of the Isothermal lines in the interior of
the globe, is evident.

December 17. — Dr Abercrombie in the Chair. The follow-
ing Communications were read :

1. On the Law which connects the Elastic Force of Vajx)ur
with its Temperature. By John Scott Russell, Esq.

* The values of A are 1.164, 1.176, 1.076 in the same order as before.
VOL. XXVI. NO. LII. APRIL 1839. E 6

426 Proceedings of the Werner ia7i Society.

2. Abstract of a Paper on Results of Observations made with
Wheweirs New Anemometer. By Mr John Ranken.
Communicated by Professor Forbes.

January 7. 1839. — Br Aberceombie in the Chair. The
following Communications were read :
1. Notice respecting an Intermitting Brine Spring discharging

Carbonic Acid Gas, near Kissingen in Bavaria. By

Professor Forbes.

This paper printed in the present number of the Journal.

% Notice on the Geology of Gottland, from the Observa-
tions of Mr Laing. By Dr Traill.
Gottland has a length of about seventy-six English miles, and its
greatest breadth is thirty-four miles. Its general surface is flat, and
in no point does it rise more than 200 feet above the sea. About
one-tenth of its surface exhibits an oolitic limestone, bordered by a
narrow stripe of sandstone on each side ; which evidently belongs to
the oolitic formation, from the nature of the organic remains found
in them.

Petrifactions found in Gottland.

A. In the Mountain Limestone.

Crustacea BracJiiopoda

Calymene, 4 species. Atrypa, 7 species.

Asaphus caudatus. Terebratula, 8 species.

Cytherina Balthica. Crinodea

Cephalopoda Aprocrinites, 2 species.

Orthoceratites, 5 species. Actiocrinites, 3 species.

Ammonites Dalmanni. • Cyathocrinites, 3 species. ,

Nautilites complanatus. Other Encrinites, 5 or 6 species.

Gasteropoda Spharonites

Turbinites, 2 or 3 species. S. Omatus.

Delphinula, 6 species. Corallina

Euomphalus, 4 species. Catenepora, 2 species.

Turritella cingulata. Aulopora, 2 species.

Acephala Syringopora, 4 species.

Modiola Gothlandica. Calomopora, 5 species.

Tellina Gothlandica. Flustra lanceolata.

JBrachiopoda Sarcinula organum.

Septaena, 4 species. Astrea, 3 species.

Orthis, 5 species. Meandrina.

Eyrtia, 2 species. Fungites patellaris.

Delthyris, 7 species. Cyclolites numismalis.

Proceedings of the Wernerian Society. 427

CoraUina CoraUina

Turbinolia, 4 species. Retepbra Clathrata.

Cyathophyllum, 6 species. Aloi/onia

Lithodendron oculinum. Scyphia Empleura.

Caryophylla, 2 species. Siplionia praemorsa.

Milleflora solida. , Phacites Gothlandicus.
Nulliflora.

B. In the Oolite and Sandstone.

Calymene I31umenbachL Orthis, 2 species.

Cytherina. Delthyris sulcata.

Belemnites. Atrypa reticularis.

Turritellites. Terebratula plicatella.

Plagiostoma giganteura. Aulopora* serpens.

Avicula, 2 species. Calamopora Gothlandica.

Area. Flusti*a lanceolata.

Pectunculus. Phacites Gothlandicus.

Lephaena Englypha.

3. Notice regarding some points in Hydrodynamics that have

been mismiderstood. By Mr Scott Russell.

Proceedings of the Wemerian Natural History Society.
(Contimiedjrom Veil, xxv., p. 199.)

The Thirty-second Session of this Society commenced on the
24th November 1838, when the following gentlemen were elected
ofl&ce-bearers for 1838-39 : —

President.

Robert Jameson, Esq. F.R.SS.L. & E. Professor of Natural Historpr in the

University of Edinburgh.

Vice-Presidents.
Dr Charles Anderson, M.R.CS. Dr R. K. Gheville, F.R.S.E.
WiXLiAM Copland, Esq. F.R.S.E. John Sligo, Esq. F.R.S.E.
Secretary.— Dr Pat. Neill, F.R.S.E. Librarian.— 3. Wii^soVy Esq. F.R.S.E.

Assist. Sec T. J. Torrie, Esq. F.R.S.E. Painter.— T. Syme, Esq.

Treamrer.—A. G. Ellis, Esq. ^«»«t.PaMrt.— W.H.TowN8END,Eeq.

CauncU.
Dr Walter Adam, F.R.C.P. Dr Robert Hamilton, F.R.S.E.

Dr William Macdonald, F.R.S.E. Dr Graham, F.R.S.E. Profeesor of
Dr Martin Barry, F.R.S.E. Botany.

R. J. Hay Cunningham, Esq. SirWiLLiAMNEWBiGOiNO, F.R.S.E.

AV. A. Cadell, Esq. F.R.SS. L. & E.

Dec. 13. 1838 Dr R. Greville, V. P. in the Chair. Professor

Jameson read a paper on the Geology of the neighbourhood of

428 Proceedings of' the Wernenan Society.

Kelso, by Charles Le Hunte, Esq. {published in the last number of
this Journal) p. 144). He likewise read extracts from a paper on
a Singular Mode of Propagation among the Lower Animals, by Sir
John Graham Dalyell {published in the last number of this Journal
p. 152). Dr Traill exhibited various specimens and engravings of
the foot-marks of the Cheiiotherium occurring in the Red Sand-
stone of Cheshire, near Liverpool. There were laid on the table
Meteorological Observations made at Athens by Captain Macadam,
and a comparative Register of the Rain-gauge kept at the Royal
Botanic Garden, Inverleith Row, during the years 1835 and 1836.

Jan. 12. 1839 — John Sligo, Esq. V.P. in the Chair Dr

Robert Paterson read a paper on the Artesian Wells of Clackman-
nanshire, and on the illustrations they afford of the doctrine of
central heat. The Assistant- Secretary read a memoir by Dr
Goring, entitled " Remarks on the climate and productions of De-
vonshire." Professor Jameson exhibited two rare Fishes from the
Pentland Firth, sent to him by the Duchess-Countess of Suther-
land— viz, the Labrus carneus, or trimaculatus, and the Gadus mi-
nutus. He also shewed a large Cinereous Eagle, being one of two
birds which had the boldness to attack a traveller last week near
Newton- Stewart, in Galloway.

Jan. 26. — William Copland, Esq. V. P. in the Chair Mr

Smith of Jordanhill read an Account of farther Observations made
by him on the elevated Marine Beaches of the Basin of the Clyde.
Dr Traill exhibited a specimen of the Bergmehl of Sweden. Pro-
fessor Jameson exhibited a very fine specimen of Flexible Sand-
stone from the Himalaya Mountains, transmitted by Dr R. Steven-
son.

Feb. 9 John Sligo, Esq. V.P. in the Chair. — The Assistant Se-
cretary read, \st, Dr Goring's Remarks on the comparative merits of
the Reflecting Microscope of Sir David Brewster, and the Catadiop-
tric Engiscope of Professor Amici of Modena, with an Account of a
new Reflecting Telescope for terrestrial objects ; and, 2d, Notices
of the Geology of the Greek Islands, by D. Macadam, Esq., illus-
trated by numerous specimens. Professor Wallace then explained
by a model his solution of the Miner's Problem.

Feb. 28 — Dr Traill, formerly V.P., in the Chair. Mr Edward
Forbes read a memoir on the Asteriadse of the Irish Sea, illustrat-
ing it by an extensive series of specimens. Professor Jameson ex-
hibited a fine specimen of the Beaumaris Shark, and pointed ou
the characters which distinguish it from the Porbeagle Shark.

Proceedings of the Botanical Socieli/. 429

March 9. — Professor Jameson, P. in the Chair. — Mr Cnnningham
read an Account of the early published descriptions of the Islands
of Eigg, Rurac, and Canna. Dr Traill then read a paper on a new
locality for the Carbonate of Baryta, and on the economical uses to
which the sulphate and carbonate are now applied in England, par^
ticularly in the adulteration of white lead. Mr Torrie exhibited a
remarkable specimen of foot-marks on a slab of Red Sandstone,
from Craigs Quarry, near Dumfries. Mr Cunningham exhibited
specimens of Amethyst, from the Clinkstone of Blackford Hill.

Botanical Society nf Edinburgh.

%th N(yDember 1838. — Professor Christison, V. P. in the Chair. —
1. Professor Graham read an account of a visit which he, along
with some friends, had paid to the West of Ireland in August last,
to examine its botanical productions. It was stated that the moun-
tains of Cunnamara present very little of the alpine vpgetation with
which the mountains of Scotland are clothed, — a difference pro-
bably arising from their structure ; the summits, or nearly two-thirds
of their height, being composed of the most unproductive quartz.
Near the base of the mountains some micaceous soil exists, and
there a little alpine vegetation was found. The only peculiarity
which the quartz presented was abundance of Saxifraga umbrosa.
Menziesia polifolia was found to be scattered over a larger extent
of country than was expected, being met with in abundance on the
road-sides from within a few miles of Galway to Clifden, the most
westerly point visited. Cnicus pratensis occupied the situation which
Cnicus heterophyllus usually holds in Scotland, — the latter not yet
having been seen in Ireland. Pimpinella magna occurred in pro-
fusion along the road-sides between Galway and Oughterai-d. Erica
Mediterranea was ascertained to have been found in three stations
in the west of Ireland, considerably remote from each other. The
introduction of Erica carnea into the Irish Flora was understood to
have arisen from a mistake.

2. Mr Forbes exhibited specimens of the true Primula elcUior of
Jacquin, gathered by him during the summer on the mountains of
Styria. He pointed out the distinctions between these and the
British specimens, and maintained that no true Primula elatior had
been found in Britain. He also laid before the Society some spe-
cimens of Viola pinnata from Mount Nanas in Carniola, in order

430 New Publications.

to shew, that the form of the filamental appendages in that species
indicates a passage from the true Violets to the Pansies.

3. Professor Graham stated, that some months ago he had re-
ceived from Dr Christison a root of Ipomcea purga, now believed
to be the plant which yields the true Jalap of commerce ; and that
when cultivated in the stove it had grown freely and produced
flowers. It is altogether a different plant from that previously in
cultivation.

\^th December. — Professor Graham, President in the Chair. —
1. Mr Brand read a paper containing remarks on the Statistics of
British Botany, intended to illustrate the plan proposed to be adopted
in the formation of the Botanical Society's British Herbarium. 2.
Mr Forbes read an account of an Excursion to the Mountains of
Ternova in Carniola, in company with Signor Tommasini of Trieste.

10^^ January 1839. — Professor Graham, President in the Chair.
— 1. Mr Forbes read some observations on certain Continental
Plants allied to British Species. 2. Mr Herbert Giraud read the
first part of a paper on the Structure and Functions of Pollen. 3.
Mr Brand read a communication explanatory of a scheme which he
proposed for the publication of a work under the Society's direc-
tion, intended to give a general but comprehensive view of the
whole range of Botanical science.

\Ath February. — Professor Graham, President in the Chair. —
1. Mr Herbert Giraud read the second part of his paper " On the
Structure and Functions of Pollen."

NEW PUBLICATIONS.

1. The Silurian System, founded on Geological Researches, S;c, ; by Ro-
derick Impey MuRCHisoN, Esq. F.R.S., &c. &c. &c. Two volumes
quarto, with numerous pictorial and geognostical engravings, and a
Geological Map. Murray, London. 1839.

Any attempt on our part to lay before our readers a critical
analysis of these valuable volumes, would engage us in the dis-
cussion of almost every topic of interest connected with geolo-
gical science, which, ho v. ever, the limited space of this Jour-
nal forbids, and the already great celebrity of the work, now
in the hands of every geologist, renders entirely unnecessary.
Mr Murchison, however, we may remark, now enjoys the plea-
sure and satisfaction, it is true after years of incessant labour in

New Publications. 431

the field and in the closet, of having first made naturalists mi-
nutely acquainted with all the geological relations of a system
of rocks, forming the oldest portion of the great secondary class,
and of thus signalising himself by a geological achievement, of
which there are not many similar examples on record since the
time of Werner, the founder of modern geognosy.

2. A Sketch of the Geology of Fife and the Lothians, including detailed
Descriptions of Arthur's Seat and Pentland Hills ; by Charles Mac-
LAREN, Esq. F.R.S.E. Post 8vo. pp. 236. 1839, Adam and
Charles Black.

The middle district of Scotland, especially the neighbour-
hood of Edinburgh, has been long celebrated on account of its
numerous and varied displays of instructive geognostical pheno-
mena, a circumstance -which has enabled the geologists of the
Edinburgh school to contribute in an eminent degree to the
advancement of geological science. These phenomena at an
early period engaged the attention of Hutton and Hall, names
famous in the history of geology ; and Playfair drew from the
same source illustrations for ,his universally known classical
work. Dr Hope by his lectures in our University on the
Huttonian Theory of the Earth, and Professor Jameson by his
field labours, publications, and lectures in the University, pre-
pared the way for the geology of Scotland of Boue, and the
well known memoirs of Robert Bald, Esq., Lord Greenock,
Dr Hibbert, R. J. Hay Cunningham, Esq., David Milne,
Esq., and this sketch of the geology of Fife and the Lothians,
&c., by Charles Maclaren, Esq.

Mr Maclaren is already favourably known to the geological
world by his investigations. The present work is the result
of much patient and laborious examination, carried on during
a short period each summer for a series of years, as a recrea-
tion from incessant literary avocations. The author commenced
it with the idea of limiting his sketch to Arthur's Seat and the
Pentland Hills, but afterwards extended his plan ; and the
reader is now also presented with a geological account of the
district between the Lammermuirs and Ochils, " and a sum-
mary of the evidence from which a rise in the bed of the Firth
of Forth has been inferred." We have derived great pleasure

432 New Publications.

-from the perusal of this volume ; and are sure that the minute
and interesting details it contains regarding many of the most
curious geological features of our vicinity, and the useful map,
sections, and numerous woodcuts by which it is illustrated, will
afford much information to the geologist, and will prove a va-
luable ffuide to the traveller.

0. Journal of the Asiatic Society of Bengal. Edited by Mr Prinsep. —
Numbers for April, May, June, and July 1838, Calcutta ; and Messrs
W. H. Allen & Co. London.

In these numbers we find the following articles immediately
connected with physical science : —

April — Note of a visit to the Niti Pass of the Grand Hima-
layan Chain, by J. H. Batten, Esq. C. S. Additional notice
on the Geography of Cochin China, by the Most Reverend
Jean Louis, Bishop of Isauropolis. — On the Reg-Ruwan or
Moving Sand, a singular phenomenon of sound near Cabul,
with a sketch, by Captain Alexander Burnes. — A letter to'Dr
Heifer on the Zoology of Tenasserim and the neighbouring
provinces, by Assistant-Surgeon J. T. Pearson. — Mode of
manufacture of the Salumba Salt of Upper India, extracted
from a report by C. Gubbins, Esq., C. S.— Proceedings of the
Asiatic Society. — Meteorological Register. Maij, — On the
application of a new method of Block-printing, with examples
of unedited coins, printed in fac simile, by James Prinsep, Sec,
&c. — Note on the affinities of Galathea of Lamarck (Potamophila
of Sowerby), a genus of Fluviatile Testacea, by W. H. Ben-
son, Esq., Bengal Civil Service. — Account of the Hurricane
or Whirlwind of the 8th April 1830, by Mr J. Floyd (com-
municated by J. H. Patton, Esq., Magistrate of the 24 Per-
gunnahs). — Proceedings of the Asiatic Society. — Meteorolo-
gical Register. June, — Some account of a visit to the plain
of Koh-i-Daman, the mining district of Ghorband, and the pass
of Hindu Kush, with a few general observations respecting the
structure and conformation of the country from the Indus to
Kabul, by P. B. Lord, M. B., in medical charge of the Kabul
Mission. — Proceedings of the Asiatic Society. — Meteorological
Register. July. — Excursion to the Eastward, No. 1. — Native
account of washing for Gold in Assam, by Moneeram, Revenue

New Publications. 4S3

Sheristadar, Bur Bundaree. — Further information on the gold
washings of Assam, extracted from Captain Hannay'*8 commu-
nications to Captain Jenkins, agent to the Governor- General
in Assam. — Note on a Fossil Ruminant genus allied to Giraffi-
dae in the Siwalik Hills, by Captain P. T. Cautley. — Proceed-
ings of the Asiatic Society. — Meteorological Register.

4. Dictionary of Arts and Manufactures, and Mines ; by Andrew Ure,
M.D., F.R.S. Parts V, VI, VII. Longman & Co.

In these parts the following are the prominent and most in-
teresting articles, Gas-Light, Glass-making, Gold, Gunpowder,
Hat manufacture, Indigo, Irpn, Lead, Metallurgy, Mines, and
Mint.

6. Zoology of the Voyage of H» M. Ship Beagle, wider the Command of
Captain Fitzroy, during the years 1832 to 1836.

Since our former notice of this valuable work, the following
numbers have been published.

Birds. — Part 2d of the Birds, of which the beautiful draw-
ings are by the Goulds, the letterpress by Mr Darwin. The
descriptive part includes nearly all the accipitrine birds met
with during the expedition. Mr Darwin''s account of the Con-
dor is the best in our language.

Recent Mammalia^ by Mr Waterhouse. A third number of
this division of the Zoology has appeared, entirely devoted to
the murine tribe, illustrated by plates of great beauty.

Fossil Mammalia^ by Mr Owen. A second number has
reached us. It contains the conclusion of the description of
the large extinct mammiferous animal, referable to the order
Pachydermata, but with affinities to the Ruminantia, and
especially to the Camelida?, named Macrauchenia ; also, as
usual with this excellent observer, a masterly description of
the fragment of a Cranium of an extinct animal, indicative of
a new genus of Edentata, and for which is proposed the name
of Glossotherium ; and an account of a mutilated Lower Jaw
and Teeth, on which he proposes to found a sub-genus of Me-
gatheroid Edentata, under the name of Mylodcyn, The nine
admirable plates in this part are illustrative of the Osteology
of the Macrauchenia, Glossotherium, and Mylodon.

434 List of Patents.

6. Illustrations of the Zoology of Southern Africa, S^c. S^c. By Andrew
Smith, M.D., Surgeon to the Forces, and Director of the Expedition
into the Interior of Africa. 4to : Smith, Elder and Company, Lon-
don.

The following are the animals described, and the natural his-
tory given in the Sd, Sd, and 4th Numbers of Dr Smith's richly
ornamented and valuable work.

Mammalia. — 1. Erinacasus frontalis, Smith. 2. Herpestes
badius, Smith. 3. Sciurus cepapi. Smith. Hippopotamus
amphibius. Maris Temminckii, Smith.

Aves, — Accipiter polyzonoides, Smith. Prionops talacoma.
Crateropus Jardinii, Smith. Euplectes taha, Smith. Phile-
taerus lepidus, Smith. Vidua axillaris, Smith. Merops Bul-
lockoides, Smith. Pterocles variegatus. Francolinus Swain-
sonii, Smith. Francolinus Natalensis, Smith. Francolinus
pileatus, Smith. Francolinus subtorquatus, Smith. Hermi-
podius lepurana, Smith.
Reptilia. — Echidna ionorata, Smith. Lycodon capensis, Smith,

Insecta. — The 3d Number of the Illustrations confined to
the Insecta, will be highly prized by entomologists, having been
contributed by W. S. Macleay, Esq. It contains two memoirs,
— one on the Cetoniidae of South Africa, the other on the Bra-
chyurous Decapod Crustacea, brought from the Cape by Dr
Smith. The illustrative coloured plates are perfect represen-
tations of the objects described.

List of Patents granted for Scotland from 14M December
1838 to 15th March 1839.

1. To Joseph Green, of Ranelagh Grove, Chelsea, in the county of
Middlesex, gentleman, for an invention of " an Improvement in Ovens." —
21st December 1838.

2. To Thomas Nicholas Raper, of Greek Street, Soho, in the county of
Middlesex, gentleman, for an invention of " improvements in rendering fa-
brics and leather water-proof." — 21st December 1838.

3. To John Howarth, of Aldermanbury, partly in consequence of a com-
munication from a certain foreigner residing abroad, and partly by inven-
tion of his own, for " certain improvements in machinery for spinning, ro-
ving, doubling, and twisting cotton and other fibrous materials." — 21st De-
cember 1838.

4. To Stephen Geary, of Hamilton Place, New Road, in the county of

List ofPai^nUs. 48$

Middlesex, architect, for an invention of ^ improvements in the preparati(»
of fuel."— 29th December 1838.

5. To William BaowN, of Port-Dundas, near Glasgow, clerk, in conse-
quence of a communication from a foreigner residing abroad, for an inven-
tion of " a flooring machine for planing, reducing to an uniform thickness
and breadth, and grooving, featliering or tongueiug wood used for floom
and other purposes." — 29th December 1838.

6. To Henry Huntley Mohun, of Regent's Pork, in the coonty of
Middlesex, M.D., for an invention of " improvements in apparatus for pro-
ducing light and heat."— 29th December 1838.

7. To Joseph Davies, of Nelson Square, in thfe county of Surrey, gentle-
man, for an invention of " a composition for protecting wood from flame.'*
—4th January 1839.

8. To William Wainwright Potts, of Burslem, in the county of Staf-
ford, china and earthenware manufacturer, for an invention of " certain im-
provements in machines applicable to the printing or producing patterns in
one or more colours, or metallic preparations to be transferred to earthen.
ware, porcelain, china, glass, metal, wood, cloth, paper, papier machie, bone,
slate, marble, and other suitable substances." — 7th January 1839.

9. To William Gossaoe, of Stoke Prior, in the county of Worcester,
manufacturing chemist, for an invention of " certain improvements in ma-
nufacturing iron." — 12th January 1839.

10. To Joseph Fraser, of Halifax, in the county of York, railway-con-
ti-actor, for an invention of " certain improvements in the apparatus of ma-
chineiy to be employed as centerings or supporters in the construction of
bridges and arches, and in tunnels or other mining operations." — 14th Ja-

' nuary 1839.

11. To John Fowler, of Birmingham, in the county of Warwick, gentle-
man, for an invention of " certain improvements in prexmring or manufac-
turing sulphuric acid." — 14th January 1839.

12. To Richard Thomas Beck, in the parish of Little Stonham, in the
county of Suffblk, gentleman, in consequence of a communication from a fo-
reigner residing abroad, for an invention of " new or improved apparatus
or mechanism for obtaining power and motion, to be used as a mechanical
agent generally, which he intends to denominate roke eircp." — 14th Janu-
ary 1839.

13. To William Brindlet, of Birmingham, in the county of Warwick
paper-tray manufacturer, for an invention of " certain improved arrange-
ments in the construction of screw-presses." — 17th January 1839.

14. To John Small, of Old Jewr}', in the city of London, merchant, in
consequence of a communication from a foreigner residing abroad, for an
invention of " improvements in the manufacture of thread or yam and pa-
per by the application of certain flbrous materials not hitherto so employ-
ed."—21st January 1839.

15. To Thomas Betts, of Smithfield Bars, in the city of London, recti-
fier, in consequence of a communication from a certain foreigner residing'
abroad, for an invention of " improvements in the process of preparing ^•
rituous liquors in the making of brandy." — 21st January 1839.

16. To Benjamin Ledger Shaw, of Honley, near Iluddersfield, in the

List of Patents.

county of York, clothier, for an invention of " improvements in preparing
wool for, and in the manufacture of woollen cloths, parts of which improve-
ments are applicable to the weaving of other fabrics." — 21st January 1839.

17. To John Chanter, of Earl Street, Blackfriars, in the county of Mid-
dlesex, Esq., and Peter Borrie, of Dundee, engineer, for an invention of
" improvements applicable to steam-boilers." — 21st January 1839.

18. To Edward Cooper, of Piccadilly, in the county of Middlesex, sta-
tioner, in consequence of a communication made to him by a certain fo-
reigner residing abroad, for an invention of " improvements in the manu-
facture of paper." — 23d January 1839.

19. To Peter Taylor, of Birchen Bower, within Chadderton, in the
county of Lancaster, paper-maker and slate-merchant, for an invention of
" improvements in machinery for propelling vessels, carriages, and machi-
nery, parts of which improvements are applicable to the raising of water."
—23d January 1839.

20. To Frederick Cayley Worsley, of Holywell Street, Westminster,
in the county of Middlesex, Esq., for an invention of " certain improve-
ments in locomotive engines and carriages." — 24th January 1839.

21. To Thomas Walker, of Birmingham, in the coimty of Warwick,
clock-maker, for an invention of " improvements in steam-engines, which
improvements are also applicable to the raising or forcing fluids." — 24th Ja-
nuary 1839.

22. To Thomas Sweetapple, of Catteshall Mill, Godalming, in the coun-
ty of Surrey, paper-maker, for an invention of" an improvement or improve-
ments in the machinery for making paper." — 28 th January 1839.

23. To John Wilson, of Liverpool, in the county of Lancaster, lecturer
on chemistry, for an invention of " certain improvements in the process of
manufacturing alkali from common salt." — 30tli January 1839.

24. To Sally Thompson, of North Place, Gray's Inn Road, in the county
of Middlesex, for an invention of " certain additions to locks or fastenings
for doors of buildings, and of cabinets, and for drawers, chests, and other re-
ceptacles, for the purpose of affording greater security against intrusion by
means of keys improperly obtained." — 31st January 1839.

25. To Job Cutler, of Lady Poole Lane, Spark Brook, in the parish of
Aston, in the borough of Birmingham, in the county of Warwick ; and
Thomas Gregory Hancock, of Princess Street, in the borough aforesaid,
machinist, for an invention of " an improved method of condensing the steam
in steam-engines, and supplying their boilers with the water thereby form-
ed."—31st January 1839.

26. To Horace Cory, of Narrow Street, Limehouse, in the county of
Middlesex, bachelor of medicine, for an invention of " improvements in the
manufacture of white lead." — 7th February 1839.

27. To Edward Samuell, of Liverpool, merchant, for an invention of
" improvements in the manufacture of soda." — 7th February 1839.

28. To Timothy Burstall, of Leith, in that part of the United King-
dom called Scotland, engineei-, for an invention of " certain improvements
in the steam-engine and in apparatus to be used therewith, or with any
other construction of the steam-engine, or any other motive power, for the

List of Patents. 437

more smootli and easy conveyance of goods and passengers on land and wa-
ter, part of which will be applicable to water-power." — 11th Febiniary 1839.

29. To Charles Gabriel, Baron de Snaree, of Red Lion S^juare, in the
county of Middlesex, Colonel in the French ser\'ice ; and William Pow-
TiFEX, of Shoe Lane, in the city of London, coppersmith, for an invention of
" a new mode of obtaining vegetable extracts." — 12th February 1839.

30. To Morton Balmanno, of Queen Street, Cheapside, in the city of
London, merchant, for an invention of " a new and improved method of
making and manufacturing paper pasteboard, felt, and tissues," communi-
cated by a foreigner residing abroad." — 14th February 1839.

31.^To Joseph BuRCH,*of Bankside, Blackfriars, in the county of Surrey,
calico-printer and designer, for an invention of " certain improvements in
printing cotton, woollen, paper, and other fabrics and materials." — 19th Fe-
bruary- 1839.

32. To Harrison Grey Dyar, of Cavendish Square, gentleman, and
John Hemming, gentleman, of Edward Street, Cavendish Square, both in
the county of Middlesex, for an invention of " improvements in the manu-
facture of carbonate of soda." — 19th February 1839.

33. To Edward Pearson Tee, of Bamsley, in the county of York, dyer
and linen manufacturer, for an invention of " improvements in weaving linen
and other fabrics."— 20th February 1839.

34. To Joseph Bunnett, of Deptford, in the county of Kent, for an in-
vention of" improvements in steam-engines." — 20th February 1839.

35. To Alexander Borland, of Paisley, in the county of Renfrew, in
Scotland, for an invention of " a machine for measuring water and other
liquids and registering the quantity thereof." — 23d February 1839.

36. To Sir James Caleb Anderson, of Buttevant Castle, in the county
of Cork, Baronet, for an invention of " certain improvements in locomotive
engines, which are partly applicable to other purposes." — 26th February
1839.

37. To Orlando Jones, of Rotherfield Street, Islington, in the county of
Middlesex, accountant, for an invention of " improvements in the manufac-
ture of starch, and the converting the refuse arising in or from such manu-
facture to divers useful purposes." — 27th February 1839.

38. To Frederick le Mesurier, of New Street, Saint Peter's Port, in
the island of Guernsey, gentleman, for an invention of " a certain improve-
ment, or certain improvements in the construction of pumps for raising wa-
ter or other fluids."— 28th February 1839.

39. To Richard Whytock, of Edinburgh, in that part of the United
Kingdom called Scotland, manufacturer ; and George Clink, of the same
place, colour-maker, for an invention of " further improvements in the pro-
cess and apparatus for the production of regular figures or patterns in carpets
and other fabrics, in relation to which a patent was granted to the said
Richard Whytock on the 8th of September 1832, and generally in the mode
of producing party-colours on yams or threads of worsted, cotton, silk, and
other fibrous substances." — 6th March 1839.

40. To Pierre Armand, Lecomte de FoNTAiNEMOHEAti, of Charles
Street, City Road, in the county of Middlesex, for an invention of ** certain
new and improved metallic alloys, to be used in various cases as substitutes

438 List of Patents,

for zinc, cast-iron, copper, and other metals," being a communication from a
foreigner residing abroad." — 8tli March 1839.

41. To Benjamik Goodfellow, of Hyde, in the comity of Chester, me-
chanic, for an invention of " certain improvements in metallic pistons." — 8th
March 1839.

42. To John Hawkshav/, of Manchester, in the county of Lancaster,
civil engineer, for an invention of " certain improvements in mechanism or
apparatus applicable to railways, and also to carriages to be used thereon.''
—8th March 1839.

43. To John Muia junior, merchant in Glasgow, for an invention of
" certain improvements in the apparatus connected with the discharging
press for conducting, distributing, and applying the discharging liquors and
the dyeing hquors."— 11th March 1839.

44. To Thojias Vaux, of Woodford Bridge, in the county of Essex,
land-surveyor, for an invention of" improvements in tilling and fertilizing
land."— 13th March 1839.

45. To Alexander Croll, of Greenwich, in the county of Kent, che-
mist, for an invention of" improvements in the manufacture of gas for the
purpose of affording light ."—13th March 1839.

47. To Moses Poole, of the Patent Office, Lincoln's Inn, in the county
of Middlesex, gentleman, in consequence of a communication from a certain
foreigner residing abroad, for an invention of " certain improvements in
tanning."— 13th JVIarch 1839.

48. To Henry Ross, of Leicester, worsted manufacturer, far an inven-
tion of " improvements in machinery for combing and druwing wool and
certain description of hair." — 13th March 1839.

49. To James Walton, of Sowerby Bridge, in the parish of Halifax, in
the county of York, cloth-dresser and frizer, for an invention of " certain
improvements in machinery for making wire-cards." — 13th March 1839.

50. To Henry Huntley Mohun, of Regent's Park, in the county of
Middlesex, M.D., for an invention of " improvements in the composition and
manufacture of fuel, and in furnaces for the consumption of such and other
kinds of fuel."— 13th March 1839.

51. To Josias Christopher Gamble, of Saint Helens, in the county of
Lancaster, manufacturing chemist, for an invention of " improvements in
apparatus for the manufacture of sulphate of soda, muriatic acid, chlorine,
and chlorides."— 13th March 1839.

52. To J ABIES Russell, of Handsworth, in the county of Stafford, glass-
tube manufacturer, assignee of Cornelius Whitehouse, of Wednesbun'^, in
the said county of Stafford, of an extension of six years, from 26th May
1839, of a patent granted to the said Cornelius Whitehouse for an invention
of " certain improvements in manufacturing tubes for gas and other pur-
poses."—15th March 1839.

53. To Joseph Rayner and Joseph W^hitehead RAYNER,late of Bir-
mingham, in the county of Warwick, but now of the city of Coventry, civil
engineers, and Henry Sasiuel Rayner, of Ripley, in the Icounty of
Derby, civil engineer, for an invention of " divers new and important im-
provements in machinery for roving, spinning, an^^<^|wJ«tJM^|^t^n, flax,
silk, wool, and other fibrous materials." — 15th Mai

( 439 )

INDEX,

Allan, Mr, his meteorological table for Elgin, year 1838, 397.

Arago, M., his historical eloge of J. Fourier, 1, 217.

his observations on thunder and lightning, 81, 275.

Arts, Society of, for Scotland, proceedings, 199.

Atmospherical phenomena, the more important, considered, by Pro-
fessor Kaeratz, 244.

Atmospheric pressure, effects of, on the tidal waters of Devon and
Cornwall, 415.

Asiatic Society of Bengal, Journal of, for March 1838, 218 — for
April, May, Jane, July, 1838, 432. '

Barry, Martin, Dr, researches on embryology, first series, 203.

Botanical Society, proceedings of, 429;

Bischof, Gustav, Professor, on the natural history of volcanos and

earthquakes, 25, 347.
Brown, Mr, on the mucilage of faci, 409.

Carlisle, Anthony, Sir, on arborescent figures in the two divisions of
animal and vegetable structures,and in mineral formations, 344.

Dalyell, John Graham, Sir, on a singular mode of propagation
among the lower animals, 152.

Dunbar, Wi.liam, Rev., meteorological observations at Applegarth
in Dumfriesshire, 396.

Daubeny, Charles, M. D., objections to the chemical theory of vol-
canos, 291.

Deshayes, G. P. Mr, his Traite Elementaire de Conchyliologie, no-
ticed, 212.

Dowie, James, Mr, observations on boots and shoes, with reference
to the structure and action of the human foot, 401.

Forbes, James, Professor, account of an intermitting brine spring

discharging carbonic acid gas, near Kissingen in Bavaria,

306. '

Fourier, Joseph, eloge of, by M. Arago, 1, 217.
Fnchs', Nepomuk, chemical views regarding the formation of rocks,

which seem to afford new arguments in favour of Neptunism,

182.

Galbraith, William, Mr, on geodetical surveying and trigonometri-
cal levelling, 158.

Graham, Professor, description of several new and rare plants
which have lately flowered in the neighbourhood of Edinburgh,
chiefly in the Royal Botanic Garden, 194,419.
* Gray, Lord, his meteorological table for 1838, 398.

Hunte, Charles Le, Mr, on the geology of the neighbourhood of
Kelso, 144.

440 Index.

Kaemtz, L. F., Professor, remarks on the more important atmo-
spherical p])en(»raena, 244.

Kelso, observations on its g^eclogy, 144.

Kissingen, intermitting brine spring of, described by Professor
Forbes, 306.

Lea, Isaac, observations on the genus unio, noticed, 213.
Lightning and thunder, observations on, by Arago, 81, 275.

Maclaren, Mr, geology of Fife and the Lothians, noticed, 431.

Melloni, M., upon the alleged influence which the roughness and
the polish of surfaces exercise upon the emissive power of bo-
dies, in reference to the experiments of Professor Sir John
Leslie, 299.

Murchison, Mr, on the silurian system, noticed, 430.

Neptunism, views that appear to be in favour of, by N. Fuchs of
Munich, 182.

Patents, list of, granted in Scotland from 15th September to 14th
December 1838, 214 — from 14th December to 15th March
1839, 434.

Royal Society of Edinburgh, proceedings of, 422.

Russell, John Scott, F. R. S., on the vibration of suspension bridges

and other structures, and the means of preventing injury from

this cause, 38G.

Sang, Edward, F. R. S. E., notice of an erroneous method of using
the theodolite, with a strict analysis of the effects of various
arrangements of readers, 173 — on a method of obtaining the
greatest possible degree of exactitude from the data of a sur-
vey, 327.

Shepard, Charles, M. D., report of the geological survey of Con-
necticut, noticed, 213.

Smith's Zoology of Southern Africa, noticed, 434.

Stevenson, David, civil-engineer, sketch of the civil-engineering of
North America, noticed, 206.

Thunder and lightning, observations on, by Arago, 81, 275.

Ure, Andrew, M. D., dictionary of arts, manufactures, and mines,
noticed, 213.

Wauchope, Robert, Capt. R. N., on quantity of saline matter in
sea water in lat. 0°, 33' N., and long. 8°, 16' E. ; also result of
experiments on temperature of the sea at great depths, and
account of gale of wind off the Cape of Good Hope, 399.

Wernerian Natural History Society, proceedings of, 426 — memoirs
of, for 1831-37, noticed, 208.*

Zetterstedt, J. W., Insecta Lapponica, noticed, 209.
Zoologv^tlTe^yage of H. M. Beagle, noticed, 433.

INTED BY NEILL & CO. EDINBURGH.