THE

EDINBURGH NEW

PHILOSOPHICAL JOURNAL,

PROGRESSIVE DISCOVBRTEr AND IMPROVEMENTS

IN THE

SCIENCES AND THE ARTS.

CONOUCTED BY

ROBERT JAMESON,

AJCeiUS FROrsSSOR or natural history, LKCTURBR on mineralogy, and KEKPfeB 0#
THB MU8BOM IN THE UNIVERSITY OF EDINBURGH;

Fellow of the Royal Societies of London and Edinburgh ; of the Antiquarian, Wernerian and Horti-
cultural Socieliesof Edinburgh ; Honorary Member of the Royal Irish Academy, and of the Royal
Dublin Society ; Fellow of the Royal, Llnnean and Royal Geological Societies of London ; Ho-
norary Member of the Asiatic Society of Calcutta } of the Royal Geological Society of Cotnwall,
and of the Cambridge PhUosophical Society ; of the Yorlc, Bristol, Cambrian, Whitby, Northern,
and Cork Institutions; of the Natural History Society of Northumberland, Durham, and New-
castle ; 'of the Royal Society of Sciences of Denmark ; of the Royal Academy of Sciences of Berlin ;
of the Royal Academy of Naples ; of the Imperial Natural History Society of Moscow ; of the
Imperial Pharmaceutical Society of Petersburgh; of the Natural History Society of Wetterau;
of the Mlneralogical Society of Jena ; of the Royal Mineralogical Society 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 Geological Society of France; of the
South African Institution of the Cape of Good Hope ; of the Franklin Institute of the State of
Pennsylvania for the 1-rdmotion of the Mechanic Arts ; of the Geological Society of Pennsylvania,
4c. Sfc.

APRIL. ..OCTOBER 1836.
VOL. XXI.

to BE CONTINUED QUARTERLY*

EDINBURGH :

ADAM & CHARLES BLACK^ EDINBURGH;
LONGMAN, REES, ORME, BROWN, GREEN & LONGMAN, LONDON.

1836.

PMNTBD BY NBILL & COMPANY, OLD FISHMARKIT.

CONTENTS.

Art. I. On the Geology of Auvergne, particularly in connexion
with the Origin of Trap Rocks and the Elevation
Theory. By Professor Forbes. Communicated by
the Author, ------ Page 1

II. Questions for Solution relating to Meteorology, Hy-
drography, and the Art of Navigation. By M.
Arago. (Continued from vol. XX. p. 405,) - 21

I. Mean height of the Barometer. 2. Of the influence
of different winds on the heights of the Barometer,
3. On the diurnal variations of the Barometer. 4. Ob-
servations on Rain. 5. Rain in a perfectly clear sky.
6. Magnetism ; Diurnal variations of the Declina-
tion ; Inclinations ; Intensity. 7. Luminous Me-
teors ; on Lightning ; Falling-stars ; Zodaical light ;
Aurora Borealis ; the Rainbow ; Halos. 8. Pheno-
mena of the Sea ; on the means of drawing up Sea-
water from great^depths, and discovering in what pro-
portion the.two chief constituents of the atmospheric
air are contained in it. 9. Marine Currents ; on the
cause of Currents ; Sea of Weeds ; Temperature of
Currents ; Temperature of the Sea at great depths ;
Temperature of Shoals ; Height of Waves ; Visibility
of Shoals; Water-spouts; Depressions of the Hori-
aon. 10. Miscellaneous Observations ; rising of the
Coast of Chili ; Earthquakes ; Declination and In-
clination of the Magnetic Needle, ... 67

III. Observations on the Sense of Touch, including an Ana-

lysis of Weber's Works on that subject. By Dr
Graves of Dublin, ----- 67

IV. On the Composition of the Water of the Lake Elton

in Asiatic Russia, compared with the Water of the
Ocean and with that of the Caspian Sea. By Mr

H. Rose, 80

V. Farther Illustrations of the Propagation of Scottish
Zoophytes. By John Graham Dalyell, Esq.
Communicated by the Author, - - _ 88

VI. Letter from Theodore Virlet to M. Arago, on the Phe-
nomenon of Dolomisation, and the Transformation
of Rocks in general, - - ' -' - - 95

11 CONTENTS.

Art. VII. An Account of some Experiments and Observations
on the Parr, and on the Ova of the Salmon, prov-
ing the Parr to be the Young of the Salmon. By
Mr John Shaw. Communicated by the Author, 99

VIII. Abstract of a Meteorological Journal for the year

1835, kept at the Elgin Institution, - - 111

IX. Kinfauns' Meteorological Table for 1835, - 112

X. Meteorological Observations made at Castle Toward,

during the years 1834-5, - - - - 113

XI. Abstract of Register of the Thermometer, Baro-
meter, and Rain-gauge, kept at Regent Terrace,
Edinburgh, in 1835, - - - - 114

XII. Meteorological Table, extracted from a Journal
kept at Carlisle in 1835, (above the level of the
Sea 45 feet). By Mr Joseph Atkinson, - 114

XIII. State of the Barometer, Thermometer, &c. at

Whitehaven for 1835, - - - - 115

XIV. Annual Depth of Rain at Kendal in Cumberland,

from 1829 to 1835 inclusive. By Mr Wake^
FIELD. Communicated to the Magazine of Popu-
lar Science, No. 1. - - - - - 116

XV. On the Geology of Massa Carrara. By Professor

Frederick Hoffmann, - - - - 116

XVI. 1. Observations on the Annular Solar Eclipse which

occurred on the 15th of May 1836, by William
Galbraith, Esq., ----- 126

2. Observations on the Annular Solar Eclipse,

by Commander Alexander Milne. - - 129

3. Observations made with Leslie's Photometer du-
ring the Annular Eclipse, by E. Sang, Esq., 134

XVII. Instructions for Making and Registering Meteoro-

logical Observations at various Stations in Southern
Africa and other Countries in the South Sea, as

also at Sea, - 135

General Observations. — 1. General Recommendationa
and Precautions. 2. Of the Times of Observation and

OONTKNTS. Ill

Registry. 3. Of Meteorological Instruments, and
first, of the Barometer and its attached Thermometer ;
of the Kxtemal Thermometer ; of the Maximum
and Minimum, or Self-registering Thermometer ; of
Thermometers Buried in the Earth ; of the Temper-
ature of the Sea ; of the Hygrometer ; of the Wind ;
of the State of the Sky ; of Lightning and Thunder ;
and of the Electrical State of the Air.

XVIII. On a Method of Drilling, Turning, and Working
Glass, by means of Turpentine. By Mr John
Adie, - - - - - - - 149

XIX. Temperature of Quadrupeds, Birds, Fishes, Plants,
Trees, and Earths, as ascertained at different times
and places in Arctic America, during Captain
Back's Expedition. By Mr King, Surgeon to
the Expedition, - - - - - 150

XX. General Table of Meteorological Observations at

Fort Vancouver, from June 1. 1834 to May 13.
1835. By Dr M. Gairdnbb, - - - 152

XXI. 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, - - 154

XXII. Proceedings of the Royal Society of Edinburgh, 158

XXIII. Proceedings of the Wernerian Natural History

Society, 160

XXIV. Proceedings of the Society for the Encourage-

ment of the Useful Arts in Scotland, - - 164

XXV. Scientific Intelligence, - - - - 169

1. Shower of Falling Stars in Russia, on the night be-

tween the 12th and 13th November 1832, . jb.

2. Disengagement of Inflammable Gas in the Interior

of Mines, I'JQ

3. Analysis ofa Clay Ironstone, forming a bed twelve

inches thick, in the Coal Formation at Wardie,
to the westward of Newhaven, near Edinburgh.
By William Gregory, Esq. M. D., . . I73

4. Volcanos of Kamtschatka, . . . . J 74

CONTENTS.

6. Tenii>erature of the Mines at the Leadhills, and
of some Springs on the Rhine, . . . 174

6. Progressive Rise of a portion of the bottom of the

Mediterranean, . . . • . . 175

7. Remains of Quadrupeds in the Oolitic System of

Rocks, 176

8. Temperature of the different Tertiary Deposits

at the Epoch of their Formation, . . I77

6. The Level of the Caspian much below that of the

Ocean, 180

10. Spring at the Summit cf a Mountam, . . 180

11. Fossil Ferns, 181

12. Prospects of the Negro Population in South Ame-

rica, and the gradual extinction of the original
inhabitants of the New World, . . . 182

13. Historical and Statistical Researches on the Causes

of the Plague 184

XXVI. New Publications, —

1. The Physical and Intellectual Constitution of Man

considered. By Edward Meryon, F.R.C.S.,
&c. London : Smith, Elder, & Company. 1836.
8vo, pp. 240 186

2. A Geological Sketch of the Tertiary Formation in

the Provinces of Grenada and Murcia in Spain,
&c. By Brigadier Charles Silvertop. Lon-
don : Longman & Rees, 8vo, pp. 236, with plates, 186

3. Ascent to the Summit of Mont Blanc in 1834.

By Martin Barry, M.D. F.R.S.E., Member
of the Wernerian Society, &c. Edinburgh :
Blackwood & Sons, 8vo, pp. 119, with plates, 186

4. The Earth ; its Physical Condition and most re-

markable Phenomena. By W. M. Hi g gins,
F.G.S., Lecturer on Natural Philosophy at Guy's
Hospital. London: Orr & Smith. 1836. 12mo,
PP-512, 186

XX Vn. List of Patents granted in Scotland from 18th

March to 16th June 1836, - - - - 187

CONTENTS.

Art. I. On Volcanos and Craters of Elevation. By Leopold

Von Buch, - - - Page 189

n. On the Temperature- of the Earth's Surface during
the Tertiary Period. By M. Elib de Beau-
mont, - . - - 206

:' :iin. Account of one of the most important Results of the
Investigations of M. Vbnetz, regarding the Pre-
sent and Earlier Condition of the Glaciers of the
Canton Vallais. By Johann von Charpenjier.
With later additions by the Author, - 210

IV. Memoir on the Metamorphoses in the Macrourae or

Long-tailed Crustacea, exemplified in the Prawn
(Palaemon serratus). By W. V. Thompson, Esq.,
F. L. S., Deputy Inspector- General of Hospitals.
(Communicated by Sir James MacGrigor, Bart.,
M.D., F.R.S., &c., - - - 221

V. Considerations respecting a New Power which acts in

the Formation of Organic Bodies. By M. Bbr-
ZELius, - - - - 223

.,yi. Account of a Method of separating Small Quantities
of Arsenic from Substances with which it may be
mixed. By James Marsh, Esq. of the Royal
Arsenal, Woolwich. (Communicated to the So-
ciety of Arts of London), - - 229

n CONTENTS.

Art. VII. Mean Temperature of Montreal, Lower Canada, for
the period of Ten Years, viz. from 1826 to 1835
inclusive. By Archibald Hall, M.D., - 236
VIII. Second Report of the Meteorological Committee of
the South African Literary and Scientific Insti-
tution, - - - - 23fl^

IX. Note, by M. Alphonse de Candolle, concern-
ing M. Marcel de Serres's Essay upon the Ques-
tion, Whether the Examination made, in the Coal
Formation of Canada and Baffin's Bay, of Plants
analogous to those which now flourish in Equa-
torial Regions, proves a Change in the Inclination
of the Ecliptic, - - - 247

X. Inquiry in relation to the alleged influence of
Colour on the Radiation of Non-luminous Heat.
By A. D. Bache, Professor of Natural Philosophy
and Chemistry, University of Pennsylvania, 249^

^l. Notes on the Natural History and Statistics of the
Island of Cerfgo and its dependencies. By Ro-
bert Jameson, Esq. Assistant Surgeon, 10th
Regiment of Foot, Corfu. Communicated by the
Author, - - - - 26^

XII. On the Formation of Hail. By M. De la Rive, 280

XIII. New Researches on the Organic Elements, and in-

timate Structure of Animal Bodies. By G. R.
Treviranus, - - - 29J>

XIV. An Account of a recently invented Patent Spring

called " The Safety Spring," applicable to car-
riages and carts of every description- By the
Rev. R. J. Barlow. With a Plate. Communi-
cated by the Author, - - - 308-

XV. Notes regarding some of the Plants observed during

the last year, in excursions from Edinburgh, espe-
cially some new stations for those of rare occur-
rence, or concerning the geographical distribution
of a few which are more common. By Dr
Graham. Communicated by the Author, - 31 f

XVI. Proceedings of the Royal Society of Edinburgh, 315^

CONTENTS. lii

Art. XVII. Proceedings of the British Association at Bristol in

August 1836, - - 319

Section A — Mathematical and Physical

Science, . . 319, 335, 360, 356, 366

B — Chemistry and Mineralogy, 325, 335, 350, 359, 367
C — Geology and Geography, 326, 335, 351, 359, 367
D — Zoology and Botany, . 329, 342, 353, 363

E.— Anatomy and Medicine, 334, 346, 354, 365, 368
F — Statistics, . . . 334, 346, 355, 366

G.— Mechanical Science, . . . 334, 347

Evening Meetings, .... 347, 366, 358

XVIII. Scientific Intelligence, - - - 369

GEOLOGY AND HYDROGRAPHY.

1. Subsidence of the Coast of Greenland, . . 369

2. Quantity and Proportion of the constituent parts of
Atmospheric Air in Water, . . . 370

3. Use of Nicol's Calcareous Spar Prism in discovering

Shoals in the Ocean, ... ib«

4. Thermal Springs in the Columbia Territory, . 371

5. Discovery of Carbonate and Sulphate of Lithia in a

Spring, . . . . . 372

6. Siliceous Sinter of Iceland, ... ib.

7. Native Mercury in Granite, . . ib.

8. Fall of part of the Dent du Midi, ... ib.

9. Trade in Chromate of Iron, . . . 374

10. Ehrenberg's new Discovery in Palaeontology

Tripoli composed wholly of Infusorial Exuviae, ib.

11. Dinotherium giganteum, . . . 375

12. Mass of Green Malachite of extraordinary size, 376

13. The Coal Formation of the United States, . ib.

14. Difference of Temperature between Granite and
Slate in the Cornish Mines, . . . ib

15. The Uniformity of the Form of Mountain Slopes in
the Higher Alps, with an attempt to explain the
facts, and an exposition of the resulting conse-
quences, ..... 377

16. On the Chalk and Calcaire grossier of Meudon, 378

BOTANY.

17. Delightful Smell on approaching tropical Idndsfrom

18. Extract of a Letter from JM. Gay to M. de Bkin-

37flF

ir CONTENT*.

ville, dated Valdivia, 6th July 1835, regarding the
habits of Leeches of Chili, and the tendency exhi-
bited by reptiles in the same country to become
viviparous, ..... 38o

II). On the Changes which the Stomach of Crabs un-
dergo during the period of casting their Shells, 381

ANTHHOPOLOOy.

20. Dreadful Effects of the Immoderate Use of Coca, 382

21. Effects of Compressed Air on the Human Body, 384

22. Manner of obtaining Blood in cases where the Vein
does not yield it readily, by Dr Burdach, . 385

23. Poisoning by Arsenic cured by the Hydrated Trit-

oxideoflron, . . , " . ib.

24. Anatomical and Physiological Remarks on Hunch-
backs, ..... 386

25. Socrates not poisoned by Hemlock, . . 387

26. Death of Mr David Douglas, . 388

Art. XIX. New Publication, . . .389

The Northern Flora, or a Description of the Wild
Plants belonging to the North and East of Scotland,
with an Account of their Places of Growth and Pro-
perties. By Alex. Murray, M. D. Part I.
8vo. Pp. 183. Adam and Charles Black, Edin-
burgh ; Brown and Company, and Clark and Son,
Aberdeen ; and Smith and Elder, London. 1836.

XX. List of Patents granted in Scotland from 7th

July to 10th September 1836, - - 391

Index, - - - - -

CORRIGENDA.

Page 132, ljne.25, /or 3 h. 2 m. 345 s. read 3h. 1 m. 54.6 s.

— 161, — I, for observed by him read observed by Dr Parnell {.thepronoun hMtlng
reference to the preceding paragraph).

THE

EDINBURGH NEW
PHILOSOPHICAL JOURNAL.

Ofi the Geology of Auvergne, particularly in connexion with the
Origin of Trap Rocks and the Elevation Theory. By Pro-
fessor Forbes. Communicated by the Author.*

It can hardly at the present day be required that I should
present any formal apology for offering my speculations on a
subject removed, as some may suppose, from those to which,
professionally, my attention is habitually directed. Yet I will-
ingly take the occasion of presenting to the Society, together
with the few and somewhat desultory observations which these
remarks are intended to introduce, some reflections on the posi-
tion which geology ought to hold in relation to the other sci-
ences ; reflections which the recent application of mathematics to
the elevation theory of Von Buch and Elie de Beaumont render
the more fitted to the present occasion.

If geologists have had reason to congratulate themselves upon
the escape of their science from the hands of the cosmogonists
of a century ago, they may perhaps one day discover that, as
regards the progress of knowledge towards the end which all
consider as the ultimate aim of science, the discovery of causes^
the reform which was happily wrought in geology, has been car-
ried to an extreme.

The great mass of exertion which has, within the last forty
years, been brought to bear upon the subject, has been, I fear
we must confess it, rather the exertion of the hand than of the
head. With a self-denial, in moderation pre-eminently praise-
worthy, have geologists, especially those of England and Germa-
ny, been accumulating and classifying ^c^^, which in inductive
philosophy essentially form the basis of reasoning. Of this we

• Read before the Royal Society of Edinburgh on 7 th and 21st Dec. 1835.
A collection of specimens illustrative of the paper, was at the same time pre-
sented to the Society.

VOL. XXI. NO. XLI. — JULY 1836. A

^ Professor Forbes on the Geology of Auvergne.

should be the last to complain, were these efforts always well
directed ; but even^the rigid canons of the Baconian school admit
of discrimination in the search of truth, a faculty nearly (though
not quite) as essential in the observer as in the experimentaHst,
and without which he cannot have the slightest clew to separate
what is important from what is trivial, — what is adapted for im-
mediate application to the ends of science, from what it would be
soon enough to detail a century hence,r — without which the re-
sults of his labour, however accurate, may be redundant, and his
painfully collected cabinet, as useless to science as if its elements
had taken their natural course to the chisel or the limekiln.

The geologist has confined himself too much to the accumu-
lation of undigested facts. He has considered his science too
much as a mere department of natural history, without refer-
ence to the far more important questions of cause producing
change, which brings it under the immediate dominion of natu-
ral philosophy. For although we cannot for a moment overlook
the bold and admirable speculations of Hutton, and the re-
searches consequent upon them conducted in the best spirit of
inductive science by Playfair and Hall, — ^it must be admit-
ted that this chapter of scientific history is in a great measure
insulated from that of the age, and that the methods and results
of these observers have scarcely been quoted, even by those who
have adopted their conclusions, without materially enlarging their
premises.

This neglect of the great ends of geology, may in some mea-
sure be ascribed to a discovery which ought to have been one
of the principal sources of their advancement. The relations of
the organized fossils found in the strata to the order of superpo-
sition of these strata, was calculated to afford an indication of
the highest value for the classification of the groups of rocks
where mineralogical characters were awanting, and for the iden-
tification of insulated deposits.

We ought not, perhaps, to be astonished that so pregnant a
discovery was carried in its consequences rather to excess. But
we could not have been prepared for the almost total devotion
with which geologists have surrendered themselves to Palaeon-
tology, — B. devotion which has produced a smile even on the
part of zoologists themselves, when they found the good-natured

Professor Forbes on iJie Geology of Auvergne. 3

facility with which the analogies of their science were received
as the canons of geology.* The consequence has been, that
geology, of late years, has become little more than a commenta-
ry on organized fossils. The great ends of the science seem to
have been forgotten, and strata are no longer examined in the
hope of detecting the proof of any mechanical or chemical change,
but simply for the sake of classifying a new plant, shell, or rep-
tile. The Dynamics of Geology have been overlooked, or, if
adverted to, have been engaged in (too often) with partial views
and inadequate preparation.

Yet it is to this point that the exertions of the geologist might
be successfully apphed. His object is the inquiry into the na-
ture of changes which have supervened in the condition of the
earth's surface. Such changes are of two kinds, mechanical and
chemical ; to investigate these, we might naturally expect that
natural philosophy and chemistry would be thought essential, —
but geologists in general have brought to their task but a very
slight acquaintance with those sciences. I am persuaded that it
will be by drawing the attention of three classes of persons, viz.
natural historians, chemists, and natural philosophers, to this
one very complicated but very important subject, that any real
advances are to be made, and perhaps even the alphabet of the
science of geology is scarcely yet formed. The natural hi^brian
is to collect the facts or data of the problems upon which the
others are to reason ; and such a division of labour has, we all
know, been productive of the highest benefit to every one of the
mixed sciences. Such geology undoubtedly is, and one, we are
persuaded, even more complex than is commonly imagined. The
ordinary theories of geological change often refer to purely hy-
pothetical cases, much simpler than those which occur in nature*
The mode of action of the forces unanimously admitted into
geology is in reality so complex, that to expect to trace an imme-
diate analogy between the conclusions of mere reasoning and

• " II nest bruit tjue des hautes revelations faites par la zoologie au profit
de la g^ologie, et que cette derni^re avec toute confiance et docility se trouve
avoir acceptees est adapt^es aiix principales base? de sa theorie. Pour moi,
je ne partage pas Tidee qui a seduit taut de personnes, et je pense tout au
contraire que I'importation n'a pas et6 aussi heureuse et aussi utile qu'on ue
la croit generalement."— Geo/ro^ St Hilaire, qu^ed *y BouL

a2

4 Professor Forbes on the Geology of Auvergne.

the phenomena of nature, would perhaps be too rash. Our ig-
norance is such, that direct comparison of observed effects of
known causes by experiment, and the observed effects of un-
Jcnozvfi causes in nature, can alone lead us to well-founded con-
clusions. Yet geologists scarcely ever think of such an appeal
to experiment. Excepting those of Sir James Hall and Mr
Gregory Watt, we can hardly quote an example.*

I have perhaps said enough to shew why I conceive that geo-
logy ought sometimes to be treated as a branch of natural phi-
losophy ; and in the hope of contributing something, however
imperfect, towards what I consider the neglected part of the
science, I have from time to time made collections in connection
with some of the leading problems, for the solution. of which
geology must be ultimately indebted to natural philosophy. One
of these is the action of heat upon rocks, and another is the me-
chanical power of elevation which igneous rocks have occasion-
ally exercised, and its consequences. Without pretending to
have devoted much special time to the inquiry, I have directed
my journeys so as to obtain the means of inspecting at least some
of the most important sites of ascertained or suspected geological
convulsion : nor can any merely local convulsions be considered
of much value; it is by the comparison of many points that we
are enabled to draw, with some degree of probability, the gene-
ral (though as yet almost empirical) conclusions whicli geology,
in its present state, admits of. With this view I have examined
the trap-rocks of our own island, the ophites of the Pyrenees, and
the serpentines of Anglesea and the Lizard, — the porphyries of
Northern Italy, the granite veins of Mount''s Bay and Glen Tilt,
— the ancient volcanos of Auvergne, the Eifcl, the Siebenge-
birge, and of Rome, — and the modern volcano of Vesuvius.
Without proposing anything like an abstract of conclusions de-
rived from these various sources, I may be permitted to offer
some considerations of a general nature on two points, to which,

• I must not be supposed to have lost sight of the experiments of Dr
Turner and Mr Karcourt in this country, and of Mitscherlich and Becquerel
(whose very important results have bj no means attained the celebrity which
they seem to deserve) on the Continent. These v, e do not ewe to geologists,
but to chemists and physic'er.s.

Professor Forbes on the Geology of Auvergne, ^

in a recent excursion to Auvergne, my attention was more par-
ticularly directed : 1. The igneous character of the trap rocks ;
2, The theory of elevation of Von Buch and Elie de Beaumont.

I. There is no better proof of the necessity of a pretty exten-
sive induction in great geological questions than liic alternate
light and obscurity which the comparison of a new country with
one little known affords. Even the most skilful analysis of one
country or mountain group cannot make up for the extension of
ideas which the examination of several affords. For example,
were we to draw our conclusions as to the nature of granite
from the single study of the British isles, of the Alps, or of
the Pyrenees singly, we should certainly arrive at very con-
siderably different results. Still more so if we have to compare
the sedimentary deposits of those three very different localities,
as the lias of the Bernese Oberland with that of Bath, or the
mineralogical character of chalk on the coast of Kent and at the
summit of the Mont Perdu. It was not the want of talent,
but the want of extended observation, which led Werner into
his greatest errors, and it is to the same cause that many of his
followers have been led to support some of his least tenable
opinions, as those respecting the origin of the trap rocks, simply
by confining their attention to a single district. No one will
deny that the origin of our Scotch trap rocks might be yet in-
volved in great doubt, had we not indubitable specimens of
igneous action wherewith to compare them : could we not com-
pare the analyses of modern lava and basalt, — their mineralogical
structure, their dykes and veins, and their enclosed minerals.
On all these points a direct •omparison was obtained, and to
those who had seen and examined both classes of phenomena,
the conclusion was irresistible. Still it required a certain effort
of abstraction to realise, amidst our trap formations, the recol-
lections of the torrefied flanks of Vesuvius or Etna, to trace the
analogy, and to pronounce upon the general identity of origin.
In Auvergne this effort of abstraction was spared. Both phe-
nomena are side by side, nor perhaps has the most determined
Neptunist ever retired from an examination of these Phlegraean
fields, without feeling his former faith shaken ; whilst the majo-
rity have read at once the recantation of their heresy, amidst the
scarcely slumbering fires of Clermont and Le Puy. (To this

B Professor Forbes on the Geology of Auvergne,

Charpentier and D'Aubuisson bear a candid testimony in their
own persons.)

The effects of heat are of two kinds, producing rocks (by
which we mean being the direct agent of their protrusion,) and
altering them. Each of these, but especially the latter, affords
a field of inquiry of the most interesting character, and often
fills up a chain of evidence as solid and as convincing as any even
in mathematical physics. Of both of these Auvergne contains
examples, though perhaps the production is more frequent than
the change of character. To go over what has been already so
well enforced, the general deductions from the phenomena of
Auvergne, is by no means my purpose ; I would rather allude
to one or two individual points which may pretend to something
of originality ; and first, I would remark, that the striking con-
viction which, as we have said, a sight of this country has
seldom failed to impart as to the origin of trap (undoubtedly
one of the most fundamental positions in geology), we attribute
quite as much to the topographical condensation of the evidence
as to its superior force. We discover in Auvergne vast plateaux
of basalt, of the origin of which we know nearly or quite as little
as of that of Salisbury Crags, near Edinburgh, or the Whin Sill
of the north of England. In close apposition to these, we have
f!ows of lava, as distinct, as rugged, and as obviously igneous
as those of Vesuvius ; — following the course of the actual valleys
issuing from scorified craters, rolling their tide of desolation into
the midst of fertility, — in short, presenting as complete a picture
of volcanic energy, even in its most frightful form, as can any
where be seen, with the single exception that all is cold and
hard. Though, as later writers have pointed out,* there may
be an insensible passage from the basalts of these platforms to
the more modern streams, we seldom fail to discover a general
reference to an older or a newer class, one anterior, the other
posterior, to the existing condition of the valleys. The basaltic
jylateaux we cannot trace to their source, the coulees of lava we
can ; the evidence of a common origin is perhaps not greater
than that which a trap rock country, and a modern volcanic
country compared would afford, only that you have no sepa-
ration of the two in point of space ; — you may stand upon
basalt and break lava ; you may compare at one instant the

• Scrdpe on the Volcanos of Central France. Lyell's Geology, vol. iii.

Professor Forbes on the Geology of Auvergne. 7

configuration of both, the constitution of both, the included
minerals of both.

The next remark I would make is an important one, and
refers to the alteration of rocks. The group of volcanic rocks
round Clermont forming what may be called the Monts Dome,
rise through an elevated table-land of granite, the flanks of
which are abundantly covered by sedimentary deposits of the
tertiary epoch. Associated with the latter are many of the
basalts. Thus in the hill of Gergovia, we have a section of
this kind, reckoning from below; 1. Tertiary limestone ; 2. Ba-
salt with nodules, and containing crystals of chalcedony ; 3.
Tertiary limestone, sometimes oolitic; 4. Basalt; 5. " Calca-
reous peperino'*' (Scrope), a sort of volcanic tufa containing veins
of compact felspar ; 6. Basalt at the summit. From the middle
bed of basalt shoot forth veins into the superincumbent calca-
reous tufaceous matter, which, in the places I examined, presents
no decided appearance of alteration by heat.- M. Dufrenoy*
thinks otherwise, and infers the posteriority of the contained
basalt lo the containing strata, which I am disposed to think
the phenomena of veins just alluded to would force us to admit,
though Mr Scrope ^ draws an opposite conclusion. This differ-
ence of opinion is not a little instructive ; and the exact paral-
lelism in that, as in other respects, between these phenomena
and those of Scotland, as well as the almost total absence of ap-
parent torrefaction at Gergovia, serve admirably to connect the
most unequivocal volcanic appearances with those of a more du-
bious character.

Mineral Character, — The mineralogical character of the
rocks of Auvergne is one of their most interestinjr features.
Dr Daubeny % has particularly alluded to the perfectly basaltic
character of the recent coulees of Gravenoire, near Clermont.
One of these, in particular, on the side next Montaudoux, pre-
sents most brilliant crystals of olivine and augite, such as our
trap rocks associated with the older formations exhibit. The
amygdaloids and compact felspars might every one be matched
in Scotland, as well as many of the trachytes of Mont Dor and

• Memoires pour servir k la Geologie de la France, torn. i.
■\ Central France, p. 92. — Mr Lyell agrees with M. Dufrenoy, Geology^
ilT. p. 259.
X I/'ttera on the Geology of Auvergne, Eit Phil. Joanml^

8 Professor Forbes on the Geology of Ativergne.

the Cantalj and the trachytic conglomerates of the latter, which
much resemble those of Arthur''s Seat. Where the trachytes
are more perfectly crystallized, containing glassy felspar in six-
sided tables, as at the Puy de Sancy, and in four-sided prisms,
as at the Capucin, both in the Mont Dor, we have a perfect
antitype in the rock of the Drachenfels ; whilst the porous but
durable lavas of the coulees of Pariou and the Puy de Nugere
(the latter forming the well known Pierre de Volvic) very closely
resemble the millstone lava of the environs of Andernach. Of
the rock called Domite I shall say nothing, because the only
proof of the prevailing hypothesis, that it is altered granite
ejected like hasty-pudding (to use the phrase of Mr Scrope), is
yet untried : we may hope for something Hke a result from Mr
Harcourt's experiments at the Low Moor iron-works. The
phonolite of the Puy de Griou, in the Cantal, is identical with
that of Blackford Hill, near Edinburgh. Again, the lavas and
scoriae of the Puy de Gravenoire and the lava of the Puy de
Come, forming the vast and sterile Cheire de TAumone, offer
the most perfect analogies to the produ(;tions of Vesuvius and
other modern volcanos. The felspathose rock of the Mont Dor
containing sulphur and alum, may be classed with that of the
Solfatara, and the tufas of every part of Auvergne may find
parallels at Ischia, at Pausilipo, and in the Campagna di Roma.

Structure, — Nor does the columnar form occur under less
remarkable circumstances. We find basaltic pillars of exquisite
symmetry, straight and bent, at Murat, in the Cantal, and in a
thousand other sites, which may rank with those of Staffa and
the Giant's Causeway. Whilst, what is far more remarkable,
we discover the most obvious traces of columnar structure in
the relatively modern lavas, as in the very remarkable locality of
Pechadoire, near Pont Gibaud, and in the still more singular
displays of the Vivarais, a country which I have not visited.

There is another circumstance respecting the structure of the
undoubtedly igneous rocks of Mont Dor well worthy of remark.
The slaty structure, so far from being opposed to the crystalline
character of the rock, is found frequently combined with it, and
that in the three leading characters of rock, trachyte, basalt,
and phonolite. The columns of trachyte behind the baths of
Mont Dor have so excessively slaty a structure, that it is with
great difficulty that we can procure fresh surfaces even in hand

Professor Forbes on the Geology of Auvergne, 9

specimens. As to basalt, its tabular form is too frequent in
Auvergne not to be remarked. But I particularly noticed vast
slabs of it in the valley above St Bonnet, one of the immense
external indentations of the group of Mont Dor. •

Two extremely picturesque eminences, not very far from the
last mentioned valley, called La Thuilliere and La Roche Sana-
doire, are composed of what has been called by almost all writers
on Auvergne, pJionolite, though it does not coincide precisely
with my idea of that rock. It is composed, however, apparently
altogether of felspar. In the case of La Thuilliere, the very
polygonal arrangement, striking when viewed at a distance,
merges into a most completely slaty structure when closely exa-
mined, the rock forming vast tabular masses which resemble
strata. To these cases we might add that of the modern lava of
the Puy Nugere, forming the coulee of Volvic, the stone of which
may be cleft into tabular masses parallel to the bed in which the
lava flowed, and these again through vertical planes coinciding
in direction with the lava stream. These remarks find an im-
portant application in considering the tabular structure of rocks
of dubious origin, such as granite, which may be even extensive-
ly slaty (as it rarely, and though sometimes is, as on the south
side of the Canigou in Roussillon, near Prats-de-MolIo), without
leading us to the conclusion of an aqueous deposition.

Passage ofrochs into one another. — I have already observed,
that, far from finding geological theories too simple, I imagine
that they are rarely complicated in any proportion to the actual
complication of nature. Especially the changes which occur
after their deposition, and which may be oftentimes repeated,
may serve to render inextricable the apparent disorder of super-
position.

It has been a general (and for the most part a well founded)
opinion, that trachytic eruptions were prior to basaltic ones ; and
that the existence of these rocks may refer to very different pe-
riods in the history of our globe. The universality of this view, a
study of Auvergne will hardly allow us to acquiesce in. I shall
confine myself at present to one curious section, which I was in-
duced especially to examine from a reference to it in Mr Scrope's
work on Auvergne * where he has called attention to the exist-

• Note p. 109.

10 Professor Forbes on the Geology ofAuvergne,

ence of basalt underlying trachyte, a fact which he says has been
denied by M. Beudant and other French geologists. That there
is a basalt there can be no doubt, and I was hence led to trace the
very curious relations of these and other strata at the same point.
This section is a natural one formed by a rivulet descending in
a cascade near the baths of Mont Dor. The general section is
a very simple one, in a descending order : —

1. Trachyte.

2. Volcanic Tufa.

3. Trachyte.

4. Volcanic Tufa.

6. Basalt passing into Trachyte.
6. Volcanic Tufa.

Of bed No. 5. it is to be remarked, that though one portion of
it be truly basaltic, black, compact, and heavy, it gradually
passes into a distinct trachyte by imperceptible gradations, a cir-
cumstance which may possibly have escaped Mr Scrope. First
the augite gradually disappears ; the rock becomes less dark and
much less heavy ; then crystals of glassy felspar commence, and
the transformation is complete. It may be observed, that the
basalt in question does not appear to contain olivine, but it is a
perfectly well characterized basalt in other respects.

+ + + + +' T Unstratified Trachyte passing into Conglomerate, r

Debris.

l^-v^Vl Trachyte.
lo"o°o°l Conplomeratc.

Frofessor Forbes on the Geology ofAuvergne, 11

It is in the 6th or lowest bed that we have the accompanying-
section. Beneath the general overlying trachyte, we have a por-
tion of the same unstratified matter passing into a trachytic con-
glomerate (a very common rock of this country). To the right
of the figure we have this same conglomerate becoming stratified,
and passing undistinguishably into common paste-like volcanic
tufa ; and in this very tufa we have veins passing from the
trachyte above, and even appearing to cut both one and the
other. We shall find ourselves reasoning in a circle if we at-
tempt to ascribe superior antiquity to any one of these substan-
ces. I am disposed to account for rather than explain such
phenomena, by changes induced in structure, and particularly
a blending of structure subsequent to the deposition of rocks by
the action of heat.

It is worthy of observation, that this bed of tufa contains por-
tions of wood in a high state of preservation.

Relative age of rocks. — The conclusion of the anteriority of
basalt to trachyte, from the section just given, and from others
in the neighbourhood, as near Quereilh, would not be quite le-
gitimate, even supposing that the basalt were .not found to blend
with trachyte. For we have seen that, in the case of Gergovia,
we must necessarily admit the insinuation of basalt posterior
to the date of the strata it traverses, and we have also a very
good specimen of this in the Mont Dor, on the great road
from the baths to Murat. But there is one remarkable fact
which seems necessarily to lead to this conclusion. In the Cautal
between Aurillac and Vic-en-Carladez, I have observed masses
of basalt inclosed in a trachytic conglomerate, a vast pudding-
stone formation with a base of trachyte, passing into and inter-
stratified with that rock.

The common opinion is, that the trachytic eruptions belong to
the oldest epoch, that the basaltic were subsequent to them, and
the phonolitic still later. Certainly there are many facts seen in
the Mont Dor and Cantal which confirm such an idea, yet pro-
bably we must not consider this as [universally true, owing to a
variety of facts, one of which I have just stated. That the
trachytic eruptions were very frequently renewed seems almost
undeniable, from the dykes of more compact trachyte which tra-
verse the older rocks, and which add so much to the sublimity

12 Professor Forbes on the Geology of Auvergne.

of the scenery (although it is not on a very great scale) in the
Gorge d'Enfer in the Mont Dor. I think we are bound to con-
clude that the rocks of this country have undergone great
changes in the constitution, structure, and mutual relation, by
causes which have acted subsequently to the convulsions which
brought them into juxtaposition. Such changes are what
theory can take little account of, though they may be most nu-
merous and most important ; and this is one of the cases in
which the processes of nature seem more involved than we can
ever venture to render our theories, which, from our limited
sources of induction, are perhaps universally ioo simple, though
we dare not render them more complicated without deserting
altogether the track of logical analogies, and running the risk of
shipwreck amidst a chaos of possible contingencies.

The relations of the igneous to the stratified rocks are also
very obscure ; we have mentioned the instance of Gcrgovia, and
we might extend our remarks to the fresh -water formations of
the Cantal. A sketch of these has been given by Messrs
Lyell and Murchison,* and also by M. Dufrenoy-|- and others.
I examined the curious sections occurring between Aurillac and
Tiesac, particularly that at the latter place, where I spent two
days. But I own that the dynamical conclusions from these
formations seem extremely^difficult. We are forced to consider
the limestone as anterior in point of date to the tufas and other
volcanic rocks, yet we frequently find masses of the latter con-
tained in the former.

Perhaps the origin of these tufas is the most difficult, and one
of the most important problems presented by the Cantal and
Mont Dor. I shall hazard a few remarks respecting them, in
concluding with a notice of the theory of elevation.

II. Theory of Elevation-Craters. — The hypothesis proposed
long ago by Von Buch, to account for certain appearances
in volcanic countries, (as in the Isle of Palma, one of the Ca-
nary Islands), amounts to this ; that, in some cases, the conical
form of volcanic mountains, instead of being assumed in virtue

• Annales des Sciences Naturelles, torn, xviii.
f Annales des Mines, 2de Serie, torn, vii-

Professor Forbes on the Geology of Auvergne. IJJ

of successively imposed coats of lava trickling down in an in-
clined position, was assumed subsequently to the horizontal de-
position of those beds, by a thrust upwards from below ; hence
such an external configuration may be independent of the vol-
canic nature of the materials. Cavities so formed are what Von
Buch terms Craters of Elevation. Tiie recently published in-
genious views of M. Elie de Beaumont, on the epochs and
modes of elevation of mountain chains, includes the theory of
Von Buch as a particular case, namely, an elevation at a point
producing a group^ instead of elevation along a line producing
a chain of mountains. Hence the groups of Mont Dor and the
Cantal have excited the particular attention of that very dis-
tinguished geologist, who, (with M. Dufrenoy), has published a
paper * expressly on the subject, which was my constant com-
panion whilst examining that country. The great excitement
which has recently prevailed amongst geologists, especially on
the Continent, about this matter, led me to examine the evi-
dences with the more attention, though my examination was
curtailed extremely by the constant annoyance of bad weather,
which I experienced in September last.

What is brought forward as the chief novelty in the general
views of MM. Elie de Beaumont and Dufrenoy, is the actual
calculation of the spaces or fissures which should be left in the
slope of the cone (or rather pyramid of many sides). That
such spaces must occur is obvious, from the circumstance that
the surface of a cone is larger than its base, and that the ma-
terials, which when united occupied only the area of the base,
are to be elevated towards a common vertex. Looking upon
the question mathematically, nothing can be clearer or more sa-
tisfactory than such a statement ; and perhaps there is room for
regret, that, in the paper alluded to, a parade of analytical re-
search appears, which adds neither to the conclusiveness nor to
the elegance of the reasonings. The effect, however, of this
novelty, cannot fail to be advantageous to geological science.
It will give to geologists, in some cases, the means of reducing
to definite trial vague trains of reasoning, and it will generally
aid in fortifying the prosecutors of this speculative science with
• Annales des Mines, 2de Serie, torn. iii.

14 Professor Forbes nn the Geology of Auvergne.

the sound principles which mathematical pliilosophy inculcates.
M. Elie de Beaumont is one of the few living geologists who
have considered a study of general physics and mechanical phi-
losophy, as a fit commencement for the prosecution of a subject
which should draw largely on both, and that in their more dif-
ficult departments. It is almost exclusively with the more in-
tractable problems of the higher mechanics that geology has to
deal ; such as the equilibrium of free heterogeneous fluids, —
the conditions of matter under circumstances which never can
exist at the surface of our globe, — the analytical theory of heat,
— the yet more imperfect rudiments of electro-magnetism, — the
action of forces upon plastic and semi-rigid materials, — the im-
pulsive force of fluids, and their motions at great depths ; —
these are but a few of the thorny paths of inquiry in which the
speculative geologist, who wishes to take sound philosophy along
with him, finds himself engaged. We should, therefore, con-
gratulate the science on finding men of enlarged views and great
acquirements, likeM.Elie de Beaumont, ready to promote a gene-
ral taste for such pursuits, even although the temptation to over
step a little the legitimate paths of mathematical investigation
should at first be too great to be resisted.* It may at least in-
duce a study of the allied sciences, when geologists themselves
begin to find the works of their fellow-labourers too abstruse for
their perusal.-[*

That the argument about the conical surface has been carried
too far can hardly be doubted. The impossibility of forming
numerical estimates in point of fact on the cases in nature, ren-
ders the whole rather a display of ingenuity than a substantive
benefit to science. The chief conclusions of any importance,
namely, that the higher the angle of elevation of the cone, the

• The reasonings of M. Elie de Beaumont have not of course failed to be
caricatured. I recollect to have seen in a French provincial journal the ob-
vious truth, that, as we proceed from the apex of the imaginary fissured cone
. towards its base, the surn, of the incomplete spaces will diminish, proved by
the aid of the differential calculus !

•t At the very time that this paper was being read, I had the satisfaction of
receiving a very remarkable physico-mathematical paper, by Mr Hopkins of
Cambridge, upon what may justly be termed the Dynamics of Geology. It
is now published in the Cambridge Transactions, and an abstract in the Philo-
sophical Magazine.

Professor Forbes on iJte Geology of Auvergne. 15

larger the fissures ; and the greater the diameter of the crater the
smaller the sum of the interrupted spaces of its circumference,
are obvious upon mere statement ; and since the comparisons
with nature do not admit of more precision, any formal calcula-
.tion goes for very little.

Yet there are very strong grounds for adopting the conclu-
sions of MM. Ehe de Beaumont and Dufrenoy, nor do I find
it easy to conceive on what grounds the earnest hostility mani-
fested to their views has been maintained. Passing over most of
the arguments which have been urged by themselves and others,
I will point out one or two which have struck myself with pecu-
liar force, as regards the Cantal and Mont Dor, and especially
the former.

1. The Cantal presents a crater-hke basin, in which rise
phonolitic cones, and from which radiate numerous valleys, like
jdeep scars, so similar to the divergent cracks of a piece of ice or
of a starred piece of glass {etoile), as to lead us to imagine that
the excellent map given by MM. Elie de Beaumont and Du-
frenoy had been drawn under the inspiration of theoretical views,
did we not find it fully confirmed by the unbiassed authority of
the accurate Cassini. An examination of the valleys, too, would
lead us to the conclusion that, in general, they are valleys of dis-
ruption, not of erosion; but admitting, as I do, after paying
long continued and earnest attention to this important and diffi-
cult question in geology, (the origin of valleys), that there seems
no universal and unimpeachable criterion between the two, I
would not now press that assertion. There is, however, this
most striking in these valleys, (I speak with most confidence of
the valley of the Cer in the Cantal, which I examined with
most care, and the same may be added of some valleys of the
Mont Dor), that they often rather contract than increase in
width, as we retire from the centre of the group, at the same
time that they are less profoundly excavated, till at last they
merge in the slightly swelling surface, exactly as the theory of
elevation would prescribe. They are frequently bounded on
either side by mural precipices, and of lateral valleys there are
almost noiie.

2. M. Elie de Beaumont has justly pointed out the regularity
of the succession of layers or coats which occur over the conical

16 Professor Forbes on the Geology of Auvergne.

surface of the mountain groups : he has hkewise observed that,
as proper lava streams are always narrovv, such an arrangement
could not occur in all directions. But there is almost a physical
impossibility to such an arrangement, namely, that, unless the
crater had an edge or lip mathematically level all round, a uni-
versal effusion of the kind which I have alluded to could not
take place; some lateral deficiency must have drawn off the ris-
ing fluid, unless we conceive a supply so boundless as to resem-
ble that of a very copious spring rising up under hydrostatic
pressure, — a phenomenon far less reconcilable with those now ob-
served than the theory of Von Buch.

3. The enormous disproportion of the valleys to the drainage
of a single conical mountain next strikes us ; and this is equally
applicable to the Mont Dor. It is hardly credible that such
and so numerous valleys could be the mere work of erosion.*

4. This and similar difficulties seem to have been so strong-
ly felt, that many or most writers have taken refuge in the
theory of earthquakes having produced these rents ; — this, how-
ever, M. Elie de Beaumont justly observes, is a begging of the
question, since separation by fracture in this case implies eleva-
tion above the horizontal plane. [The contraction from cooling
might have been mentioned, but that is wholly inadequate.]
But there seems even a stronger objection, which brings those
who entertain such views directly under the ranks of the eleva-
tion theory. Such earthquakes could not have accompanied or
occurred between the deposition of these successive layers ; for,
had this been so, we should have wanted the perfect coincidence
between five, six, or seven successive beds exhibited on each side
of these valleys, and which seem perfectly to correspond. Indeed
no overflow could have taken place after the formation, of a sin-
gle such valley, as the lava must have followed the direction
of the valley, as we see constantly amidst the Monts Dome.
Consequently the earthquakes could not have taken place until
the effusions had completely ceased, and hence correspond in

• In a memoir published since this paper was read, M. Elie de Beaumont
puts this difficulty in a forcible, and, it seems to me, not an exaggerated
light : — " On ne pourrait concevoir la reunion de Tune et I'autre circonstances,
la divergence des vallees jointe a I'existence des barrages, qu'en imaginant
poetiquementi des courans diluviens descendant du ciel en ligne perpendicu-
laire !"— Memoires pour servir, &c. tom. iii. p. 293. 1836.

Professor Forbes on the Geology of Auvergne. 17

point of time, as well as in effect, to those which the elevation
theory assumes.

5. I have already said tliat the theory of the tufas and con*
glomerates of this country appears so difficult, that I should
be unwilling to found theoretical conclusions upon them. Their
stratification, such as, in some cases, I firmly believe to exist,
affords, however, an evidence too important to be overlooked.
The section formed by the river Cer near Tiesac (in the Cah-
tal) is one of the best instances. The following memorandum
was made at the time : " I crossed the valley to examine a sec-
tion of the constituents of the mountain, exposed by a very ex-
tensive and picturesque landslip. Above the conglomerate or
tuff which forms the bottom of the valley, is a bed of compact
trachyte, very like the claystone porphyry of the Pentland Hills.
It has a tendency to columnar structure transverse to the direc-
tion of the bed, and breaks with the hammer also in that direc-
tion, though the texture of the rock indicated by the crystals is
parallel to the bed. Above this bed is one of tufaceous conglo-
merate, like those of Naples, and strongly appearing as if stra-
tified by water ; then another bed of compact trachyte ; then
coarse conglomerate ; and the whole is capped by basalt (which,
hovvever, I did not ascend high enough to meet with). The lowest
bed is of great thickness. It is extensively exposed in the chasm
below Tiesac, through which the river runs. It is a matter of
question whether this chasm is of erosion, or a crack."^ Now
the whole of these beds dip at an angle of 3° 42', at a mean, ac-
cording to M. Elie de Beaumont, though in many places consi-
derably more, from the vertex of the cone. If the third bed from
the bottom which is conformably stratified really indicate aque-
ous deposition, the conclusion is nearly irresistible that such de-
position took place whilst the bed of trachyte below was hori-
zontal ; and hence, by the reasoning of the last article, the beds
above must also have been subsequently horizontally deposited.

The importance of the question I lay before future observers,
nor shall I take upon myself to make any general statement r^
lative to these tuffs, considering the short and imperfect exami-
nation which I gave them, and the difficulties which at the time
I felt upon the subject. My observations in the valley of the
Cer were, however, carefully made, and were entirely confirmed

VOL. 5CXI. NO. XLI. JULY 1836. B

18 Professor Forbes on the Geology of Auvergne.

afterwards in the Mont Dor. The lowest tufaceous bed in the
section at the cascade of Mont Dor already given, which con-
tains recent wood, indicates, I think, a fluviatile or lacustrine
origin. The latter is rendered more probable (and it is the
most conformable to the views just stated) from the very re-
markable tufaceous deposit in a neighbouring valley, above the
spot called La Verniere, where a pumiceous conglomerate occurs
inter stratified with the most delicately deposited beds of fine
white clay, which must evidently have had their origin in still
water, l^his does not accord with the idea of Mr Scrope in his
beautifully illustrated work on this district, that such beds were
formed from the debris accumulated by torrents.

6. I must, however, observe, that the origin of these tuface-
ous beds seems to be distinct from that of the great mass of
conglomerate which occupies the base of almost all these valleys
to an immense depth. It is a proper rock, and is, as MM. Elie
de Beaumont and Dufrenoy observe, to be distinguished care-
fully from the mud eruptions by which Herculaneum was co-
vered. It has a trachytic basis, and the inclosed fragments are
generally trachyte ; so that it is probably the result of some in-
ternal interrupted process, not a recomposed rock in the proper
sense of the words. This is entirely confirmed by the undoubt-
ed mechanical energy it has exerted, as, for example, in dis-
turbing, elevating, and imbedding the tertiary stratified deposits
with which it came in contact, as described by Messrs Lyell and
Murchison*, and others. I own that the strong impression
made upon my mind (notwithstanding its prima facie improba-
bility) by the Cantal was, that this conglomerate had been the
agent of elevation of the whole group. The evidence seems to
strengthen upon reflection, nor can I easily account otherwise
for the entire occupation of the bottom of the valleys by this
conglomerate, which must have been itself fissured had it been
merely passive. At all events, the disturbance of the stratified
rocks by this material must be considered as entirely conforma-
ble to the elevation theory, and as indicating beyond any doubt
a certain amount of convulsion.

7. Upon the whole, it seems to me that the evidence of earth-
quakes subsequent to the deposition (in whatever way) of the

• Annales des Science Nat. xviii. 172.

Professor Forbes on the Geology of Auvergne. 19

Cantal and Mont Dor, is a fact so indisputable as to render the
argument about craters of elevation to a great extent merely
verbal. It is impossible to look upon either of these districtK,
and especially the latter, without perceiving incontrovertible
evidence of extensive convulsions. These convulsions could not
have taken place without elevation, and elevation is a kind of
action with which all geologists are familiar, and which has been
repeatedly appealed to by some of the warmest opponents of the
elevation craters. If this be an assumption then, it is a reason-
able one ; and the only other postulate of that theory, namely,
the extensive horizontal beds of volcanic matter, is so entirely
conformable to the facts observed in the comparatively level
ground adjoining these very mountain groups, as in fact to be
viewed as no assumption at all, or at least as possessed of equal
probability with any other opinion as to its primitive position.
I allude to the immense plateaux of basalt in the level country
of Auvergne, so faithfully and admirably delineated in Mr
Scrope^s work. There seems, therefore, so much of probability,
and so little of extravagance, in the theory, that we wonder how
it could possibly have given rise to such animated opposition.

At the same time, looking on the subject with the impartiali-
ty of a spectator, — a mere straggler into the domains of geology,
it seems perhaps not less unreasonable to expect that all cases of
such actions should yield themselves with equal facility to the
support of so simple a hypothesis. Whilst we see in the Can-
tal an example of elevation of great unity and simplicity, the
Mont Dor, though bearing no less obvious traces of upheaving
agency, seems to bid defiance to any thing like regular analysis.
To attempt to calculate, on the principles of M. Elie de Beau-
mont, the magnitude of the fissured spaces produced by three
simultaneous (or consecutive) elevations at as many points with-
in a radius of three or four miles, appears unwarrantably bold.
Nor are the rugged features of this picturesque country trans-
latable into language sufficiently definite to authorize or to
disprove such a conclusion. I own that an unbiassed and most
attentive survey of the bearings of the group from the Pic de
Sancy (the highest ground in Central France, 1887 metres
above the sea) did not lead me to this conclusion, — I mean that
three such elevations were necessary and sufficient to explain the

b2

^0 Professor Forbes on the Geology ofAuvergne.

observed phenomena. Many circumstances lead me to conclude
that the changes undergone by this district have been vastly
more complicated, more numerous, and more prolonged ; and
that it would be unreasonable to expect that such phenomena
should always be of so simple and so elementary a description.
Some facts inferring many successive changes in the materials
constituting the Mont Dor have been already adverted to.
Others it would be easy to cite. The numerous dykes of tra-
chyte and basalt are especially remarkable, and if accompanying
or in any part posterior to the general elevation, must necessa-
rily have altered most materially the configuration of the ground,
and the relations of its constituents. That the three points or
centres of elevation indicated by MM. Elie de Beaumont and
Dufrenoy, viz. the Puy de Sancy, the Puy de la Tache, and the
Roche Sanadoire, were really points of disturbance and eleva-
tion, seems scarcely to admit of doubt. The last, indeed, speaks
for itself; the spectator, placed on one of the magnificent pho-
nolitic masses of La Thuilliere or La Roche Sanadoire, finds
himself nearly surrounded by mural escarpments. But I con-
tend that there must probably have been many more centres of
effervescence, whose successive outbreaks may have materially
changed the original configuration of the district. The termina-
tions of many of the valleys differ from what the elevation theory
would point out, neither expanding into craters, nor vanishing
in mere rents, but having frequently rounded mural termina-
tions, which may be compared (as I rather think M. Elie de
Beaumont himself has done) to the oules or theatre-like termi-
nations of many of the Pyrenean valleys. One of these partial
disturbances may, I conceive, be seen in a very remarkable
crater-like cavity close to the Roc Crusau ; nor does it appear
that the disturbing energy was exhausted until it had spent it
self by the comparatively modern orifices of the Puy de Tar-
taret, the lakes Pavin, Servieres, and others.

Edikburgh, bth December 1 835.

( 21 )

Questions for Solution relating to Meteorology^ Hydrography^
and the Art of Navigatioru By M. Abago. (Continued
from Vol. XX. p. 405.)

Mean height of the Barometer. — A few years ago a positive
denial would have been given to the assertion, that there is any
permanent difference between the barometrical heights corres-
ponding in the different regions of the globe to the level of the
sea. At present such differences are regarded as not only pos-
sible but even probable. The officers of the Bonite ought there-
fore to prieserve their barometer with the most scrupulous care,
in a fit state to make observations by which every variation may
be registered for the purpose of comparison. Notice should
never fail to be made of the exact height of the bulb of the ba-
rometer above the level of the sea.

Of the influence of different "winds on the heights of the Ba-
rometer. — As soon after the memorable discovery of Toricelli
as meteorologists directed their attention to the observation of the
barometer, they perceived that in general certain winds pro-
duced a rapid ascent of the mercurial column, while opposite
winds produced a contrary effect in a manner equally decided.
The difficulty was to determine the numerical value of these in-
fluences. It was necessary, in order to evade entirely passing
and fortuitous influence, and obtain the true measure of perma-
nent causes, to operate in great numbers ; to form an estimate
from a long series of good observations made in the same locality ;
to group the winds by their precise directions ; and to deduct
the means of effects purely thermometrical.

Burckhardt undertook this labour, availing himself of twenty-
seven years of observations which Messier had made at Paris
from 1773 to 1801. If we designate by the letter H. the mean
height of the barometer at Paris, that is to say, the height deter-
mined by the average of all the observations, the means corres-
ponding to the different winds, according to Burckhardt*s calcu-
lations, will be as follows : —

22 Questions Jbr Solutio7i relating to Meteorology,

South Wind,

H.

mm.
less 3, 1

South-west,

~ 2, 9

West,

.

- 0, 4

North-west,

more 1, 3

North,

- 2,

North-east,

2- 2, 6

East,

- 1, 1

South-east,

— 0, 8

It will be seen, from the inspection of this table, that the di-
rection of the wind occasions a variation in the state of the ba-
rometer at Paris of S"'"', 1 above the mean, and of 2""*", 6 below
it, forming a total variation of 5""% 7 ; and that the opposite
winds, combined two by two, give a mean height which, in ex-
treme cases, scarcely differs by half a millimetre from the mean
of all the observations.

M. Bouvard has presented to the academy the results of an
investigation analogous to that of Burckhardt ; it is founded on
the observations of the barometer made at the observatory of
Paris from 1816 to 1831, and leads in general to the same con-
sequences. By assigning to the letter H. the signification which
we gave it in the preceding table, we shall have the following
barometrical heights, corresponding to the different directions
of the winds : —

South wind,

South-west,

West,

North-west,

North,

North-east,

East, .

South-east,

The daily observations at nine o'clock in the morning, at
mid-day, and at three in the afternoon, have all concurred in
the formation of these numbers. Very nearly the same results
will be obtained by employing only the maxima heights of nine
o'clock, and the minima heights of three o'clock.

In this instance, as well as in the table of Burckhardt, half
the suras of the heights corresponding to the opposite winds, are
nearly equal to H, that is to say to the total mean. The high-
est mean effect of the wind is 6™™, 9, which surpasses the result
afforded by the observations of Messier by l'""", 2.

H. less

mm.
3,

7

(2944 observ.

)

—

3

(2847

— -

0,

8

(3402

more

2,

(1533

—

3,

2

(2140

—

3,

2

(1390

~.

1,

7

(1248

—

1,

7

(890

Hydrography^ and the Art of Navigation, S3^

Both these tables tend to estabhsh a fact with which meteoro-
logists cannot be too strongly impressed, that in order to obtain
in our climates the mean height of the barometer, it is indispen-
sable to admit into the calculation an equal number of observa-
tions, corresponding to the winds from opposite directions.

The tables which we have just transcribed, suggest many*
scientific questions ; they lead us to inquire how this influence
of winds on the weight of the atmosphere, varies with the posi-
tion of places, with their greater or less distance from the sea,
with their latitude, &c. In the mean time, till data sufficiently
numerous be obtained to enable us to attempt the solution of
these various meteorological problems, I shall here present to
the reader the results of two series of very accurate observations,
which were communicated to the academy by MM. Schuster and
Gambart. The first were made at the School of Artillery and
Engineers at Metz, the others at the Observatory of Marseilles.

Observations at MetZy continued for Nine Years,

mm.

South wind,

H. less 2, 4

South-west,

H. ... 2, 1

West,

H. ... 0, 6

North-west,

H. more 0, 3

North, .

H. ... 2, 4

North-east,

H. ... 2, I

East, .

H. ... 1,

South-east, .

H. ... 0, 8

The difference between the extremes is sensibly less than in
the observations at Paris. At the same time, it would be pre-
mature to draw general conclusions from this fact, which may
perhaps be purely accidental.

The following seems more decisive : —

Observations at Marseilles, continued for Five Years,

South wind,

H. more 0,

South-west,

. H. ... 0, 7

West,

H. less 0, 5

North-west,

H. less 0, J)

North,

North-east,

Kast,

H. more 0, 2

South-east,

n 0, 5

84 Questions Jbr Solution relating to Meteorology/,

Although this table is incomplete, and founded on observa-
tions of only five years'* continuance, and although the north and
north-east winds are entirely omitted, there results from it no
less important a consequence than this, — that if the direction of
the winds exercise, at Marseilles, any influence on barometrical
heights, that influence is very slight, and ought not always, in
the case of winds of similar denominations, to have the same
sign as in the north of France. Thus, while at Paris the south-
west wind depresses the barometer considerably below the mean,
its influence at Marseilles is positive ; on the other hand, the
north-west wind, which causes a considerable rise in the baro-
meter at Paris, is that which produces the lowest depression at
Marseilles,

When observations such as these have been made at many
different places, they will probably put meteorologists in a con-
dition to explain a phenomenon which has hitherto baffled all
their efforts.

Of the Diurnal Variations of the Barometer. — Numerous me-
moirs have been published on the diurnal variation of the baro-
meter. This phenomenon has been studied from the equator
to the regions in the vicinity of the pole, at the level of the sea,
on the immense plateaus of America, on the insulated summits
of the highest mountains, and the cause has notwithstanding re-
mained in obscurity. It is still necessary, therefore, to multiply
observations on the subject. In our climates, the vicinity of the
sea appears to manifest itself by a sensible diminution in the ex-
tent of the diurnal oscillation ; Does the same thing take place
between the tropics ?

Observations on Rain. — Navigators occasionally speak of rains
winch fall on their vessels while traversing the equinoctial regions,
in terras which lead us to suppose that it rains much more abun-
dantly at sea than on land. But this subject still remains in the
domain of mere conjecture ; seldom has the trouble been taken to
procure exact measurements. These measurements, however,
are by no means difficult. Captain Tuckey, for example, made
many during his unfortunate expedition to the River Zaire or
Congo. We know that the Bonite will be provided with a small

Hydrography^ and the Art of Navigation. 25

udometer. It seems to us, therefore, expedient to recommend
its commander to cause it to be placed on the stern of the vesseU
in such a situation that it can neither receive the rain collected
by the sails, nor that which falls from the cordage.

Navigators will add greatly to the interest of these observa-
tions, if they determine at the same time the temperature of the
rain, and the height from which it falls.

In order to obtain the temperature of the rain with some de-
gree of accuracy, it is necessary that the mass of the water should
be considerable, relatively to the size of the vessel which con-
tains it. A metal udometer will not answer for this purpose. It
would be infinitely preferable to take a large funnel of some
light stuff, very dense in the texture, and to receive the water
which runs from the under side of it in a glass of small dimen>
sions, containing a small thermometer. So much for the tem-
perature. The elevation of the clouds in which the rain is formed
cannot be determined but during the time of the storm ; then,
the number of seconds which elapse between the appearance of
the flash and the arrival of the sound, multiplied by 337 metres
— the degree of rapidity with which sound is propagated — gives
the length of the hypothenuse of a right-angled triangle, whose
vertical side is precisely the height required. This height may
be calculated, if by means of a reflecting instrument we estimate
the angle formed with the horizon by the line which, parting
from the eye of the observer, terminates in that quarter of the
cloud where the lightning first shewed itself.

Let us suppose, for an instant, that rain falls on the vessel
whose temperature is below that which the clouds must possess,
judging from their height and the known rapidity of the decrease
of atmospheric heat ; every one will understand the place which
such a fact would occupy in meteorology.

Let us suppose, on the other hand, that during a day of hail
(for hail sometimes falls in the open sea), the same system of ol>-
servations had proved that the hailstones were formed in a region
where the temperature of the atmosphere was higher than the
point at which water congeals, and science would thus be en-
riched with a valuable result to which every future theory of
hail must necessarily be accommodated.

We could adduce many other considerations to demonstrate

26 Questions Jor Solution relating to Meteorology^

the utility of the observations we have proposed ; but the two
preceding must suffice.

Rain in a -perfectly Clear Sky. — There are phenomena of an
extraordinary description, on which science possesses {ew obser-
vations ; for this reason, that those who have had the privilege
to witness them, avoid speaking of them from an apprehension
that they might be regarded as undiscerning visionaries. In the
number of these phenomena we may rank certain rains of the
equinoctial regions.

Sometimes it rains between the tropics when the atmosphere
is perfectly pure, and the sky of the most beautiful azure ! The
drops are not very thick, but they are of larger size than the
rain-drops in our climates. The fact is certain ; we are assured
by M. Humboldt that he has observed the occurrence in the in-
terior of countries, and by Captain Beechey that he has wit-
nessed it in the open sea. With regard to the circumstances
on which such a singular precipitation of water can depend, we
are entirely ignorant of them. In Europe we sometimes see du-
ring the day, in calm and clear weather, small crystals of ice
falling gently from the air, their size increasing with every par-
ticle of humidity they congeal in their passage. Does not this
approximation put us in the way of obtaining the desired expla-
nation? Have not the large rain-drops been at first, in the
higher regions of the atmosphere, small particles of ice exces-
sively cold ; then have become, as they descended, large pieces
of ice by means of agglomeration ; and when lower still, been
melted into large drops of water ? It will be readily understood
that the only object with which these conjectures are brought
forward in this place, is to shew in what point of view the phe-
nomenon may be studied, and to stimulate our young travellers,
in particular, to observe carefully if, during these singular rains,
the region of the sky from which they fall present any traces of
halo. If such traces are perceived, however slight they may be,
the existence of crystals of ice in the higher regions of the air
will be demonstrated.

In the present day there is scarcely any country where meteo-
rolosjists are not to be found, but it must be confessed that their

Hydrography^ and the Art of Navigation. 27

observations are usually made at unsuitable hours, and with in-
struments either inaccurate in themselves, or improperly placed.
It does not now appear difficult to deduce the mean temperature
of the day from observations made at any hour ; thus a meteo-
rological table, whatever may be the hours noted in it, will be
possessed of value, by the mere condition that the instruments
employed will admit of being compared with the standard baro-
meters and thermometers.

We think it proper to recommend these comparisons to the
officers of the Bonite. Wherever they can be effected, local me-
teorological observations will be of value. A collection from the
newspapers of countries will often supply what would otherwise
be obtained with difficulty.

Magnetism.

Diurnal Variations of the Declination. — Of late years science
has been enriched with a considerable number of observations
on the diurnal variations of the magnetic needle ; but the greater
part of these observations have been made either in islands or
on the western sides of continents. Corresponding observations
made on the eastern sides would at present be very useful.
They would serve, in fact, to submit to an almost decisive proof
the greater part of the explanations of this mysterious pheno-
menon which have been promulgated.

The route of the expedition does not allow us to suppose that
the Bonite can remain long at points situated between the terres-
trial equator and the magnetic equator, such as Fernambouc,
Payta, Cape Comorin, and the Pelew Islands. Had it been
otherwise, we should have particularly recommended the erec-
tion of M. Gambey's beautiful instrument, in a firm position, at
a distance from every ferruginous mass, and that the oscillations
of the needle should have been attended to with the most scru-
pulous care.*

• At any rate we shall here present the problem, which observations inacie
at the points mentioned would serve to solve. In the northern hemispherey the
point of a horizontal magnetic needle, which turns towards the nwthy mores
from the east to the teest from Q\ o'clock in the morning tol ^ in the afternoon,
and from west to east from 1^ o'clock a. m. to the following morning. Our he-
misphere cannot be peculiar in this respect ; the same effect produced on the
north point here must be produced on the south point to the south of the

28 Questions for Solution relating to Meteorology,

Inclinations, — In general it will be attended with little ad-
vantage to bestovv much care on observing the diurnal variation
of the horizontal magnetic needle, in places where the expedi-
tion is not stationary for a whole week. It is different, how-
ever, with the other magnetic elements. Wherever the Bonite
stops, though it be only for a few hours, it is desirable to mea-
sure, if it can be accomplished, the declination, the inclination,
and the intensity.

While attempting to reconcile the observations on the incHna-
tion, made at remote periods in different regions of the earth,
not far distant from the magnetic equator, it has been ascertain-
ed, some years since, that this equator is advancing progressively
and entirely from the east to the west. At present it is sup-
equator. Thus, in the southern hemisphere^ the point of a horizontal magnetic
needle which turns towards the south, will move from east to west from 8| o'clock
in the morning till 1|: in the afternoon, and from west to east from 1^ p. m. till
the morning of next day. This observation, at least, accords with reason. But
let us compare the simultaneous movements of two needles, when referring
them to the same point, that namely which is turned towards the north. In
the southern hemisphere, the point turned towards the south moves from east to
west from 8i o'clock in the morning to \\v. m., at the same time the nortli
point of the same needle makes the contrary movement. Thus to put it de-
finitively, in the southern hemisphere, the point turned towards the north moves
from west to east from 84 o'clock a. m. till 1| p. m., which is precisely the op-
posite of the movement made by the same north point, at the same hours, in
our hemisphere.

Let us suppose that an observer, starting from Paris, advances towards the
equator. As long as he continues in our hemisphere, the north point of his
needle will make a movement every morning towafUs the west; in the other he-
misphere, the 7iorth point of the same needle will move every morning towards
the east. It is impossible that this change from a western movement to an eastern
movement can take place in a sudden manner. There must necessarily be, be-
tween the zone where the first of these movements was observed and that
■where the second takes place, a line where, in the morning, the needle will
neither move to the east nor to the west, that is to say will remain stationary.

Such a line must exist ; but where is it to be found ? Is it the magnetic
equator, the terrestrial equator, or some curve of equal intensity ?

Researches, continued during many months, in the places situated between
the terrestrial and magnetic equator, such as Fernambouc, Pay ta. Conception,
the Pelew Islands, &c., would certainly lead to the desired solution. But
many months of assiduous observation would be requisite ; for, notwithstand-
ing the skill of the observer, some brief intermissions in the investigations of
Captain Duperrey, undertaken at Conception and Payta, at the request of the
Academy, have still left some doubts on the subject.

Hydrography^ and the Art of Navigation. 29

posed that this movement is accompanied with a change of form.
The study of Hnes of equal inclination, regarded under the same
point of view, is attended with equal interest. When all these
lines shall have been traced upon the charts, it would be curious
to follow them with the eye in all their displacements and changes
of curvature ; important truths may emanate from such an ex-
amination. It will now be understood why we require as many
measurements of inclination as can be collected.

The question has been often agitated, whether, in a determi-
nate place, the inclination of the needle would mark exactly the
same degree at the surface of the ground, at a great height in
the air, and at a great depth in a mine. The absence of uni-
formity in the chemical composition of the earth, renders the
solution of this problem very difficult. If observations are
made in a balloon, the measurements are not sufficiently exact.
When the observer takes his station on a mountain, he is ex-
posed to local attractions ; ferruginous masses may then greatly
alter the position of the needle, without there being any thing to
make him aware of the fact. The same uncertainty affects ob-
servations made in the galleries of mines. Not that it is abso-
lutely impossible to determine the influence of accidental circum-
stances in each place ; but for that purpose it is necessary to
have instruments of the most perfect kind ; it is necessary to
be able to go to a distance, and in all directions, from the station
which one has chosen ; and, finally, to repeat the experiments much
more frequently than a traveller generally has an opportunity
of doing. But, however this may be, observations of this kind
are worthy of attention. Viewing the whole of them in connec-
tion» they will perhaps one day lead to some general result.

With regard to the declination, its immense utility is so much
experienced by navigators, that any recommendation on the sub-
ject would be superfluous.

Observations on Intensity. — Observations on intensity are not
of earlier date than the travels of Entrecasteaux and M. de
Humboldt, and yet they have already thrown a bright light on
the complicated, but at the same time highly interesting subject,
of terrestrial magnetism. Observations of this nature ought, in
the highest degree, to attract the attention of the officers of the

so Questions for Solution relating to Navigation,

Bonite, for at present the theorist is arrested at every step by
the want of exact measurements.

The aerial excursions of MM. Biot and Gay Lussac, former-
ly undertaken under the auspices of the Academy, were in a
great measure designed for the examination of the following im-
portant question ; Has the magnetic force, which, on the surface
of the earth, directs the magnetic needle towards the north, ex-
actly the same intensity at every height to which it may be ele-
vated ?

The observations of our two associates, those of M. de Hum-
boldt in mountainous countries, as well as the observations of
Saussure, of much older date, all seem to concur in shewing,
that at the greatest heights which man has yet reached, there is
no appreciable decrease in magnetic force.

This conclusion has recently been disputed. Some have re-
marked, that, in the ascent of M. Gay-Lussac, for example, the
thermometer which indicated 87°.8 Fahr. (-}- 31 cent.) on the
ground at the time of departure, sunk as low as 15°.8 Fahr.
(-f- 9°.0 cent.) in the region of the atmosphere where the needle
was made to oscillate a second time. But it is now proved that
the same needle, occupying the same place, and under the in-
fluence of the same force, will oscillate so much the more quick-
ly, according to the lowness of the temperature. Thus, in or-
der to make the observations in the balloon and those on the
earth comparable, it would be necessary, on account of the state
of the thermometer, to make a certain diminution in the inten-
sity indicated by the higher observations. Without this correc-
tion, the needle would appear equally attracted above and be-
low ; in spite of appearances, there was therefore a real decrease.
This diminution of the magnetic force with the elevation seems
likewise to result from the observations made in 1829, on the
summit of Mount Elbrouz (in the Caucasus), by M. Kupffer.
In this case an exact account was taken of the effects of tem-
perature, and yet diverse irregularities in the inclination threw
some doubts on the result.

We conceive, therefore, that the comparison of the magnetic
intensity, at the base and at the summit of a mountain, is a
matter which ought to be particularly recommended to the offi-
cers of the Bonite. Mowna-Roa, in the Sandwich Islands, seems

Hydrography, and the Art ()f Navigation, 81

to be a place very well adapted for the purpose. The observa-
tion may likewise be repeated on the Tacx)ra, if the expedition
stop for a few days at Arica.

LUMINOUS METEORS.

On Lightning, — M. Fusinieri has been lately studying the
effects of lightning under an entirely new point of view.

According to this philosopher, the electrical sparks issuing
from ordinary machines, which we see as they traverse the air,
contain brass in a state of fusion and incandescent molecules of
zinc, when they emanate from a brass conductor ; if the sparks
issue from a ball of silver they contain impalpable particles of
that metal. In the same way, a globe of gold gives rjse to sparks,
which contain, during their passage through the air, melted gold,
&c., &c.

In the centre of all these sparks the molecules are melted
only; but in the circumference, the metallic particles undergo a
greater or less degree of combustion, in consequence of their con-
tact with the oxygen of the atmosphere.

When a spark issuing from a globe of gold traverses a silver
plate, even of considerable thickness, there is seen on the two
surfaces of the plate, at the point where the electric spark en-
tered and emerged, a circular layer of gold, the thickness of
which must be very inconsiderable, since the natural volatiliza-
tion is sufficient to cause it to disappear entirely after a short
time. According to M. Fusinieri, these two metallic spots are
formed at the expense of the fused gold which the electric spark
contains. The deposit on the first face is nothing extraordinary ;
but, by adopting the explanation of the Italian philosopher for
the spot on the opposite surface, we are obliged to admit, that
the gold disseminated through the spark has passed, at least in
part, along with it through the whole thickness of the silver
plate ! It is unnecessary to add, that a spark issuing from a ball
of copper, gives rise to the same phenomena.

The spark which emanates from a certain metal, does not
merely lose a portion of the molecules with which it was at first
impregnated, when it traverses another metal ; but it becomes
charged with new molecules at the expense of that metal. M.
Fusinieri even asserts, that, at each passage of the spark, reci-
procal changes are produced between the two metals ; that when

S2 Questions for Solution relating to Meteorology,

the spark, for example, leaves the silver to pass to the copper,
it not only transports a portion of the first metal to the copper,
but it likewise transports the copper to the silver ! I will insist
no longer, however, on these phenomena ; I have cited them here
only with a view to shew that the sparks of our ordinary ma-
chines contain ponderable substances.

M. Fusinieri affirms that similar substances exist in lightning,
and that in this case also they are in a state of great division,
of ignition and combustion. According to him, these transported
matters are the true cause of the transient smells which thunder
always occasions, and also of the pulverulent deposits which re-
main round the fractures through which the electrical matter
has forced a passage. In these deposits, which have been too
much neglected by observers, M. Fusinieri has detected metallic
iron, iron in different degrees of oxidation, and sulphur. The
ferruginous spots left on the walls of houses may be found, wheti
strictly examined, to arise from the iron with which the lightning
was charged, at the expense of that which occurs in almost every
building ; but what is to be said regarding the sulphurous spots
on these same walls, and especially the ferruginous marks which
are found in the open field on trees struck with lightning? M.
Fusinieri conceives himself authorized to infer from these experi-
ments, that the atmosphere contains, at every height, or at least
as far as the region of stormy clouds, iron, sulphur, and other
substances on the nature of which chemical analysis has been
hitherto silent ; that the electrical spark is impregnated with
them, and that it transports them to the surface of the earth,
where they form slight deposits round points that have been
struck with the lightning.

This new method of regarding electrical phenomena, assuredly
deserves to be followed up with that accuracy which is suited to
the present state of science. Every one who witnesses the fall
of a thunderbolt, would perform a very useful service by care-
fully collecting the black or coloured matter which the electrical
fluid seems to have deposited at every stage of its progress, when
it must have undergone sudden changes in rapidity. A careful
chemical analysis of these deposits may lead to unexpected dis-
coveries of high importance.

Falling Stars. — From the time that accurate observation has

Hydrography, and the Art of Navigation, dS

been directed to falling stars, it has been seen how much these
long despised phenomena, — these pretended atmospheric meteors,
— these so-called trains of inflamed hydrogen gas, are de-
serving of attentive examination. Their parallax has already
placed them much higher than seems to accord with the sensible
limits of our atmosphere according to the received theories.*
While searching for the apparent direction in which these falling
stars usually move, it has been ascertained that even though they
are inflamed in our atmosphere, it is not from it that they ori-
ginate, but that they come from without. This direction,
which is their most habitual one, seems diametrically opposed to
the movement of the eai'th in its orbit !

It is desirable that this result should be established by the
investigation of a numerous series of observations. We have
therefore requested the officers of the watch on board the Bonite^
to note, during the whole of the voyage, the hour at which each
of these falling stars ap})ears, its angular height above the hori-
zon, and particularly, the direction of its motion. By referring
these meteors to the principal stars of the constellations which
ihey traverse, the different questions which we have indicated
may be resolved at a glance. Here, then, is a subject of research
which will occasion no fatigue. It may suffice to attach our young
countrymen to the subject, to remark how interestingit would be to
establish the fact of the earth being a planet, from proofs derived
from such phenomena as falling stars, the inconstancy of which has
become proverbial. We might add, if it were necessary, that it is
scarcely possible at present to see any other mode of explaining the
astonishing appearance of those bodies observed in America on
the night of the 12th and 13th November 1833, than by sup-
posing that besides the large planets, there move round the sun

• Comparative observations made in 1823 at Breslau, Dresden, Leipsic,
Brieg, and Gleiwitz, by Professor Brandes and^'manyof his pupils, have assign-
ed no less than 500 English miles as the height of certain falling stars.

The apparent speed of these meteors is found sometimes to be 36 miles per
second. This is nearly double' the rapidity of the earth's motion round the •
sun. Even although we were inclined to regard the half of this apparent
velocity as an illusion arising from the effect of the earth's movement in its
orbit, there would still remain 18 miles per second as the real velocity of the
star, a degree of rapidity which exceeds that of all the superior planets except
the earth.

VOL. XXI. NO, XLl. JULY 1836. C

34 Qnestlonsjor Solution relating ta Meteorology/,

myriads of small bodies which are not visible but when they
penetrate into our atmosphere and there become inflamed ; that
these asteroids (to adopt the name which Herschel long since
applied to Ceres, Pallas, Juno, and Vesta) move in a certain
sense in groups ; that others are insulated ; and that the assidu-
ous observation of these falling stars will be, at all events, the
only means of enlightening us in regard to these curious phe-
nomena.

We have just mentioned the appearance of falling stars no-
ticed in America in 1833. These meteors succeeded each
other so quickly, that they could not be counted ; but a mode-
rate calculation makes their number amount to a hundred thou-
sand.* They were seen along the eastern side of America from
the Gulf of Mexico to Halifax, from nine o''clock in the evening
to sunrise, and even, in some places, during the light of day, at
eight o'clock in the morning. All these meteors issued fiom the
same point of the shy, situate near y of the Lion ; and that not-
withstanding the altering position of this star in consequence of
the diurnal movement of the sphere. This, then, is assuredly
a very strange result, and we shall cite another which is not
less so.

The shower of falling stars in 1833, took place, as we have
already said, on the night of the 12th and 13th of November.

In 1799, a similar shower was observed in America by M. de
Humboldt ; in Greenland, by the Moravian Brothers ; and in
Germany, by various persons. The date is the night from the
ilth to the 12th of November.

•- Th,e stew vere so numerous, and appeared in so many different regions
of the sky at once, that in attempting to reckon them, one would only expect
to arrive at a very rough approximation. An observer at Boston compares
them, when at the maximum, to half the number of flakes which are seen in
the air during an ordinary fall of snow. When the phenomenon was con-
siderably on the decrease, he counted 650 stars in 15 minutes, although cir-
cumscribing his observations to a zone, which did not include the tenth part
of the visible horizon. This number, in his opinion, was not more than two
thirds of the whole ; thus there must have been 866, and in the whole of the
visible horizon, 8660. This last number would give 34,640 stars per hour.
But the phenomenon lasted for 7- hours, the number therefore that appeared
at Boston must have exceeded 240,000 ; for it must not be forgotten that the
data on which these calculations are founded, were not collected till the phe-
nomenon was considerably on the decline.

Hydrography y and the Art qf Navigation. 35

In 1832, Europe, Arabia, &c., were witnessed of the sanlc
phenomenon, but on a smaller scale. The date of its appear-
ance is again the night of the 12th to the 13th November.

This near approach to identity in the dates, authorizes w% the
more to invite our young navigators to watch attentively what-
ever may appear in the sky from 10th ^o 15th November, since
the observers who were favoured with a clear atmosphere and
expected the phenomenon last year (1834), saw maDifest traces
of it on the 12th and 13th of November.*

The Zodiacal Light. — The zodiacal light, although known
for nearly two centuries, still presents a problem which has not

• Since my report was read to the Academy, M. Berard, one of the best
informed officers in the French navy, has had the kindness to address to me
the following extract from the journal of the brig Loiret, of which he waa the
commander : —

" On the 13th November 1831, at 4 o'clock in the morning, the sky was
perfectly pure with abundance of red, but we saw a considerable number of
falling stars and luminous meteors of large size. For upwards of three heurs
there could not, on an average, be fewer than two every minute. One of the
meteors which appeared in the zenith, left au enormous train, forming a very
broad luminous band (equal to half the diameter of the moon), in which many
of the colours of the rainbow were very distinctly seen. We were then on the
coast of Spain, near Carthagena, the thermometer in the air,. 62.6 Fahr. (17'.
cent.); barometer, 30 inch. 3.4 lin. ; temperature of the sea, 18°. H centi."

On the 13th November 1835, a large and brilliant meteor fell near Belley,
in the department of Ain, and burned a barn. On the same night a falling
star, more brilliant than Jupiter, was observed at Lille by M. Belezenne.
It left behind it, in its passage, a train of sparks in every respect resemUing
those produced by a squib.

All these facts tend more and more to confirm us in the belief^ that there
exists a zone composed of millions of small bodies, whose orbits meet the
plain of the ecliptic towards the point which the earth occupies every year,
from the 11th to 13th of November. It is a new planetary world just begin-
ning to be revealed to us.

It is doubtless unnecessary for me to say how important it would be at
present to inquire whether other trains of asteroids meet the ecliptic in the
different points of that in which the earth is placed towards the 13th of No-
vember. This investigation would require to be made, for examplie, from
20th to 24th of April ; for in 1803 (I believe it ^vas on the 22d of April),
there was seen in Virginia and the ]Massachusets, from one o'clock till three
in the morning, falling stars in such numbers and in all directions, that it might
have been supposed to be a shower of rockets.

Messier relates that, on the 17th June 1 777, towards mid-day, he saw a
prodigious number of black globules pass across the sun for about fiveminutes*
Might not these globule."? likewise be asteroids ? la^^yi' ,

C 2

36 Questions for Solution relating to Meteorology^

been solved in a satisfactory manner. The study of this phe-
nomenon is chiefly reserved, by the very nature of things, to
observers placed in the equinoctial regions. They alone can
decide whether Dominique Cassini has sufficiently guarded
against the causes of error to which an observer is exposed in
our variable climates, arH whether he has sufficiently taken into
account the purity of the air, when he announced in his work
that the zodiacal light is constantly brighter in the evening than
in the morning ; that in the course of a few days its length may
vary from 60° to 100° ; that these variations are connected with
the appearance of solar spots, in such a manner that there must
have been, for instance, a direct dependence and not merely a
fortuitous coincidence, between the weakness of the zodiacal
light in 1688, and the absence of every kind of spot or foecula on
the solar disc in that same year.

It appears to us, therefore, that the Academy ought to desire
the officers of the Bonite^ during the whole time they remain
between the tropics, and when the moon does not lighten the
horizon, to be on the watch, either after sunset or before sun-ris-
ing, and take note of the constellations which the zodiacal light
traverses, of the star which indicates its point, and of the angu-
lar breadth of the phenomenon near the horizon, at a deter-
mined height. It is almost superfluous to add, that an account
must be kept of the hours when the observations were made.
The calculation of the results may be delayed without any
inconvenience till the period of returning home.

We are not ignorant, as has been already hinted, that some
very able observers regard these statements of Dominique Cas-
sini as little deserving of confidence. They are unwilling to
admit that sensible physical changes could operate simultaneously
in such an immense extent as the zodiacal light embraces. In
their opinion, the variations in intensity and length noticed by
this great astronomer, were not real, and they think that we
need go no farther for an explanation of them, than the inter-
missions of the atmospheric transparency.

It would not, perhaps, be impossible to find proof in the ob-
servations of Fatio, compared with those of Cassini, that atmo-
-spheric variations are insufficient to explain the phenomena de-
scribed by the Parisian astronomer. With respect to the objec-

Hydrography^ and the Art of Navigation. 87

tion derived from the immensity of the space in which the phy-
sical changes must operate, it has lost all its force since the phe-
nomena of the same nature exhibited by Halley's comet.

Our young countrymen ought therefore zealously to devote
themselves to the observations which we have pointed out. The
question is important, and no one can hitherto flatter himself
with having definitively solved it.

Aurora Borealis. — It is now well ascertained that there are as
many displays of polar aurora towards the southern hemisphere,
as in the Arctic Regions. Every thing leads us to think, that the
appearances of the southern aurora, and of that which we wit-
ness in Europe, follow the same laws. This, however, is mere
conjecture. If a southern aurora be seen by the officers of the
Bonite in the form of an arch, it will be important to notify ex-
actly the orientations of the points of this arc's intersection with
the horizon, and, if these cannot be obtained, the orientation of
the most elevated point. In Europe, the most elevated point
alwaj's appears to be situated in the magnetic meridian of the
place where the observer is stationed.

It has been proved by numerous researches undertaken at
Paris, that all kinds of aurora boreahs, even such as do not
appear above our horizon, and the existence of which, conse-
quently, we can learn only from the reports of observers in the
polar regions, alter decidedly the declination of the magnetic
needle, as well as its inclination and intensity. Who, then, can
presume to assert, as an argument to prove the great distance
of the aurora borealis, that it never disturbs the magnetism of
our hemisphere ? The attention which our travellers, in every
case, bestow on these phenomena, may at length throw some
light on the question. Arrangements have been formed, in order
that magnetic observations may be made at Paris during the
whole time of the Bonite's absence, at periods so near each other,
and in such a manner, that no irregularity can take place un-
perceived.

The Rainhow. — The explanation of the rainbow may be re-
garded as one of Descartes's most beautiful discoveries ; but, at
the same time, even after receiving the developments which
Newton gave to it, it is still incomplete. When we look atten-
tively at this magnificent phenomenon, we perceive under the

58 Questions for Solution rdathig to Meteorology^

red of the interior arch, numerous green and purple series, form-
ing narrow contiguous arches, well defined, and perfectly con-
centric to the principal arch. Of these supplementary arcs (for
that is the name given to them), the theory of Descartes and
Newton makes no mention, and indeed it cannot even apply to
them.

The supplementary arcs appear to be an effect of luminous
interferences. These interferences cannot be produced but by
drops of water of a certain smallness. In order that the phe-
nomenon may appear with some degree of brightness, it is ne-
cessary that the drops should not only be of the proper size,
but that at least the greater part of them should be equal in
their dimensions, almost with mathematical accuracy. If, there-
fore, the rainbows of equinoctial regions are never attended with
supplementary arcs, the circumstance would afford a proof that
the drops of water which there issue from the clouds are of
larger size, and more unequal dimensions, than in our climates.
In our ignorance of the causes of rain, this fact would by no
means be void of interest.

When the sun is low, the upper portion of the rainbow is, on
the contrary, very much elevated. It is towards this culminat-
mg region that the supplementary arcs shew themselves in great-
est splendour. Leaving that point, their colours rapidly become
feeble. In the lower regions, near the horizon, and even con-
siderably above it, no traces of them are ever seen, at least in
Europe.

It must needs be, then, that the drops of water, during their ver-
tical descent, have lost the property which they at first possessed ;
they must have laid aside the conditions necessary for eflScacious
interferences, which they do by having become much enlarged.

Is it not curious, it may be remarked in passing, to find in an
optical phenomenon, in a peculiarity merely of the rainbow, — the
proof that in Europe the quantity of rain must be so much the
less the higher we place the vessel in which it is to be received!*

The increase in the size of the drops is, no doubt, to be as-

• In the observatory at Paris, there are two receptacles in which rain water
is collected ; one of them on the terrace, the other in the court, eighty-six feet
lower than the first. In the course of a year the reservoir in the court re-
ceived eight-hundredths more water than that placed on the terrace.

Hydrography, arid the AH of Navigation. 39

cribed to the precipitation of humidity on their surface, as they
descend from the cold region whence they originated, and tra-
verse atmospheric strata, gradually becoming warmer as they
come nearer the earth. It is then almost certain that, if sup
plementary rainbows are formed in equinoctial regions, they will
never reach the horizon, as is likewise the case in Europe ; but
the comparison of the angle of the height at which they cease to
be seen, with the angle of disappearance as noticed in our climates^
seems to afford the means of obtaining meteorological results^
which no other method at present known can supply.

Halos. — In high latitudes, the vicinity of Cape Horn for ex-*
ample, the sun and the moon often appear surrounded by two
luminous circles, which meteorologists name halos. The ray of
the smallest of these circles is about 22'', the ray of the larger
is almost pxactly 46°. The first of these angular diraensiona
approaches near the minimum deviation which light under-
goes while traversing a glass prism of 60° ; the other would be
given by two prisms of 60°, or by a single prism of 90°.

It seems, therefore, natural to seek for the causes of halos, as
Mariotte has done, in the rays refracted by the floating crystals
of snow, which, as every one knows, usually present angles of
60° or 90°.

This theory, besides, has received a new confirmation, since
the power has been acquired of distinguishing between refracted
and reflected light by means of chromatic polarization. It is in
fact the colours of the first of these lights (that which is refracted)
which produces the polarized rays of the halo. What, then, still re-
mains to be known regarding this phenomenon ? It is the follow-
ing :^- According to theory, the horizontal diameter of a halo and
the vertical diameter ought to have the same angular dimensions ;
but we are assured, that these diameters are sometimes strikingly
unequal. Measurement alone can establish this fact ; for, if a
judgment has been formed by the naked eye, the causes of illusion
will not fail to explain how the most experienced natural philoso-
pher might be deceived. The reflecting circles of Borda are ad-
mirably adapted to the measurement of the angular distances at
sea. We may, therefore, without hesitation, recommend to the
officers of the Bonite, to apply the excellent instruments with

40 Questiotisjbr Solution relating to Meteorology,

which they are provided, to determine the dimensions of all the
halos tlmt appear to be elliptical. They will themselves perceive
that the inner edge of the halo, the only one which is distinctly
defined, is much better adapted for observation than the outer
edge ; but it is necessary, with regard to the sun, not to neglect
to indicate whether they have taken the centre or the edge as
the term of comparison. We likewise regard it as indispensable,
that the two rays diametrically opposite should be measured in
each direction, for certain observers have mentioned circular
halos, in which, if they are to be believed, the sun did not oc-
cupy the centre of the curve.

Trade-Winds. — Perhaps it will excite surprise to see the trade-
winds announced as still affording a subject of important inves-
tigation ; but it must be remarked, that the practice of naviga-
tors has often confined them to simple notices, with which science
cannot be satisfied. Thus it is not true, whatever may have been
alleged, that to the north of the equator these winds constantly
blow from the north-east ; and that to the south of it they blow
uniformly from the soutJi-east. The phenomena are not the
same in the two hemispheres. In each place, moreover, they
change with the seasons. Daily observations of the real direc-
tion, and as far as practicable of the force of the eastern winds
which prevail in equatorial regions, would therefore be a useful
acquisition to meteorology.

The vicinity of continents, on the western sides especially, mo-
difies the trade-winds in their strength and direction. It some-
times even happens that they are replaced by a west wind.
Wherever this change of the wind occurs, it is desirable to note
the time, the bearing of the neighbouring country, its distance,
and its general aspect. In order to shew the utility of this last
recommendation, it is enough to say, that a sandy country, for
example, will have a much speedier and more active influence,
than one covered with forests or any other kind of vegetation.

The sea which washes the western side of Mexico, from Pa-
nama to the peninsula of California, between 8° and S2° north
latitude, will afford an opportunity to the officers of the Bonite
of observing a complete inversion of the trade- winds. They will
find, as we are informed by Captain Basil Hall, a nearly per-
manent west wind, in a situation when the east wind of the equi-

Hydrography , and the Art of Navigation. 41

noctial regions might be expected to prevail. In these latitudes^
it would be curious to ascertain to what distance from the coast
this anomaly exists ; and at what longitude the trade-wind re-
sumes, so to speak, its laws.

According to the most generally adopted explanation of the
trade-winds, there ought constantly to be found, between the
tropics, a higher wind, blowing in an opposite direction from tliat
at the surface of the earth. Numerous proofs have been already
collected of the existence of this counter-current. Careful ob-
servation of elevated clouds, particularly those named '^ pom-
meUs^ ought to afford indications of great value to meteorology.

The periods, strength, and extent of the monsoons will form,
in short, a subject for study in which, notwithstanding a multi-
tude of important observations on the subject, much yet remains
to be gleaned.

Phenomena of the Sea.
On the means of drawing up Sea-water from great depths^
and discovering in what proportion the two chief constituent
principles of atmospheric air are contained in it.* — Chemists
have long since proved, that water becomes impregnated with
the gases which rest on its surface. This absorption is effected
by means of a true chemical affinity exerted on the different
gases, and when its effects on oxygen and azote, the two princi«
pal constituents of atmospheric air, are carefully examined, it is
found to be much stronger in regard to the first than the se-
cond. It hence follows, that the waters of seas and rivers, from
being always in contact with the atmosphere, become at length
impregnated with a mixture of gases, among which oxygen pre-
dominates. Indeed, the very accurate experiments of MM.
Humboldt and Gay Lussac have proved that rain-water, the
water of the Seine, and snow-water, contain a mixture of oxy-
gen and azote, which amounts from 29 to 32 parts of oxygen in
100 ; while the proportion of oxygen in atmospheric air is con-
stantly equal to 21 parts, and this in all seasons and climates.
MM. de Humboldt and Proven9al have besides determined the
entire volume of mingled gases contained in water near the sur-
face, and it was 55 of the volume of water.

• This section of the instructions wa? communicated to M. Arago by M.
Biot.

iJ! Questionsjbr Solution relating to Meteorology,

^ It follows as a necessary consequence of these properties, that
the vast extent of sea which covers a large part of the globe, is
impregnated with a mixture of gases, the proportions of which,
near the surface, must be nearly the same as those just men-
tioned. I have ascertained that it is likewise so at the depth of
a thousand metres ; for sea-water, drawn from that depth, af-
forded me a mixture which contained 28 parts of oxygen in 100.
This experiment I formerly made in the Mediterranean.

But here many important questions in terrestrial physics pre-
isent themselves, which the apparatus I then employed did not
enable me to solve. In proportion as we descend into the depths
of the sea, the pressure of the superior portion becomes greater ;
and as a column of sea-water, ten metres in height, is nearly of
the same weight as a column of air of the same base from th6
surface of the earth to the limit of the atmosphere, it follows
that, at the depth of a thousand metres, the water sustains a
pressure of a hundred atmospheres. How enormous, then, must
this pressure be on the lower beds, if the mean depth of the sea,
at a distance from the coasts, extends to several leagues, as the
laws of gravitation seem to indicate !* It is likewise proved, by
direct experiments, that water, when in contact at the surface
with compressed gases, and also sustaining their pressure, ab-
sorbs the same volume of these gases as if they were subjected
to the pressure of a single atmosphere merely ; so that the weight
absorbed becomes proportionably greater. If, then, the sin-
gle fact of a uniform absorption, propagated from one bed to
another throughout the whole mass of waters, be sufficient to
account for the presence of a considerable volume of air, how
greatly must the quantity be increased if it be in proportion to
the pressure according to the varying depth ! As this satura-
tion must have been in gradual operation since the seas were
formed, it must have modified by degrees the state of the atmo-
sphere, and perhaps continues to modify it still, if the affinity
which produces it is not satisfied. The influence of these phe-
nomena on the state of the atmosphere, and consequently on the
conditions of the existence of living beings on the surface of the
globe, well entitles them to be studied in order to have the ex-
tent of their operation ascertained.

• IMecanique Celeste, torn, ii, p. 200.

Hydrography^ and the Art of Navigation. 43

For this purpose, it is necessary to draw sea- water from a
great depth, at a distance from Jand, and to bring it to the sur-
face with all the air which it contains. This air must then be
disengaged by boiling, its volume measured under the ordinary
pressure of the atmosphere, and finally subjected to a chemical
analysis. In these operations, the only difficulty is to draw the
water from the desired depth, and bring it to the surface with-
out allowing any of its contents to escape. Care must be taken
not to employ vessels which are empty or filled with air merely,
designed to open at the assigned depth and admit the water ; for
the pressure to which they will be subjected will cause the wa-
ter to filter through the joints of the most perfect closing
plates {pbturateurs)y or break the vessel if these resist. And,
lastly, if the gaseous mixture contained in the deep-lying beds
is subjected to the same pressure which they undergo, it will
expand in the inverse proportion when the apparatus is brought
near the surface, and will either escape by the closing plate
(ohturateur) or burst the vessel containing it. In order to avoid
these effects, a hollow glass cylinder ought to be employed, clos-
ed at one extremity by a solid plate of metal, thus forming a
true bucket provided with a handle, to which a cord is attached
that it may be Jet down to the bottom of the sea. This bucket
being empty, and open to the surrounding water, descends into
the different beds without being injured by the pressure. When
it has reached the required depth, a cord is drawn which is at-
tached to its lower part, and by which it is reversed. This second
cord is then employed to draw up the apparatus, and in order
that it may not get entangled with the other, it is kept at the
other end of the ship. But this cylinder of glass has a double
bottom, one fixed, the other moveable. The latter is in reality
the piston of an air-pump, which descends alone, by its own
weight, when the bucket is drawn back ; and, at the same time,
the bottom fixes to a small hole furnished with a valve, which
opens from without inwards by the pressure of the surrounding
water, and allows it to enter into the empty space made by the
descending piston. When the latter has descended, and the
space filled, the valve in the bottom closes by its own spring,
and the enclosed water is thus separated and kept apart till it
arrive at the surface. But, if this water contain compressed air,

44 Questions Jbr Solution relating to Meteorology,

nothing will counteract its expansive tendency when it is brought
to the surface, where the pressure of the water from without is
removed ; it will then either escape or burst the apparatus.
To guard against this, a free issue must be provided for all
possible expansion either of the water or air. For this purpose
the fixed bottom is furnished with a lateral canal which leads to
a gas-bladder ; the latter having been first filled with water, then
emptied and pressed together before the apparatus was sunk.
This bladder will receive all the air which the water may dis-
engage on approaching the surface ; and, if any be disengaged,
it will return more or less inflated. Then, by closing the stop-
cocks with which the canal is provided, it may be separated
from the vessel containing the water, its volume measured, and
the enclosed air analyzed ; after which what may still remain in
the water may be examined, and likewise any other substance
which the water may hold in solution. Such is the apparatus
which has been entrusted to the commander of the Bonite ; and
the zeal as well as intelligence of that officer, affords us the as-
surance, that it will be usefully employed, under his directions,
to solve the various questions relating to terrestrial physics indi-
cated above ; questions which, besides their purely scientific in-
terest, have an additional importance attached to them, by the
knowledge which their solution would supply respecting the
permanence or changeableness of our atmosphere, and the con-
ditions of the existence of living creatures found in the depths
of the sea.

Marine Currents.
The Atlantic Ocean, South Sea, and the Mediterranean, are tra-
versed by numerous currents, which are the more dangerous from
carrying vessels out of their proper course, without the pilot
suspecting their influence, and, in cloudy weather, he has no
means of ascertaining it. Among phenomena relating to the
sea, and considered in the double relation of theory and prac-
tice, there is certainly none more deserving of the highest degree
of attention on the part of navigators of every country. The
numerous memoirs and works specially appropriated to the sub-
ject, such as those of Ducoudray, Romme, and even the posthu-
mous and able treatise of Major Rennel, which has just appear-

Hydrography^ and the Art of Navigation. 45

ed, are very far, in my opinion, from having exhausted the sub*
ject. Of this the reader will be able to judge.

On the cause of Currents, — The most remarkable currents
studied by navigators are, in the Atlantic : —

The current, which, after having gone round the bank of
Agullas and the Cape of Good Hope, advances from south to
north along the western side of Africa as far as the Gulf of
Guinea.

The current termed equinoctial, which invariably flows from
east to west on both sides of the equator, between Africa and
America.

The current which, after having issued from the Gulf of
Mexico by the Straits of Bahama, flows at a certain distance
along the coasts of the United States towards N.E. as far as the
bank of Nantucket, where it changes its direction.

Lastly, the current, by the action of which the waters of the
ocean which bathe the coasts of Spain, Portugal, and Africa
from Cape Finisterre as far as the parallel of the Canaries, are
all directed towards the Straits of Gibraltar.

What can be the cause of these currents ?

The trade-winds, according to some, by continually blowing
in the Indian Ocean from east to west, must produce a liquid
intumescence on the eastern coast of Africa near the equator. This
accumulated water flows continually from north to south through
the Straits of Mosambique. When it reaches the parallel of
the Cape of Good Hope, the eastern wall or mound which had
hitherto maintained it disappearing, the water necessarily flows
westward. It is thus that the current of the Agullas is
formed.

The equinoctial current of the Atlantic is attributed to the
constant impulsion of the trade-wind on the waters in the vici*
nity of the equator to the north and south.

The Atlantic equinoctial current, in this respect resembling
the equinoctial current of the Indian sea, must produce a great
accumulation of water along the first coast which presents itself
as a barrier to it ; that coast is America. From this results a
general movement of the Caribbean sea towards the strait which
separates the eastern point of Yucatan from the western point of
Cuba, as well as an elevation of the level of the sea in the Gulf

46 Questions Jbr Solution relating to Meteorology,

of Mexico ; and, lastly, that kind of cascade formed by the ac-
cumulated water in the Gulf, where it escapes from the Strait of
Bahama, the continuation of which forms the gulf-stream.

With respect to the current flowing towards the Straits of
Gibraltar, it may be caiised by the lower level of the Mediter-
ranean, and this depression of its surface may itself be occasion-
ed by its excessive evaporation which the influx of the tributary
rivers is insufficient to compensate.

These explanations are simple ; they appear to rest on phy-
sical causes, the action of which must take place in the sense
supposed ; the most intelligent observers, Franklin, Rennel, &c.,
have adopted them ; and yet I am about to prove that they are
not so completely established by observation, measurement, and
experiment, as to prevent us from entertaining legitimate doubts
on the subject.

A continued and strong wind raises the level of the sea along
the coast towards which it tends to direct the water ; thus, at
Brest, Lorient, Rochefort, &c., the tide is always highest, other
circumstances being equal, during a west wind. On the oppo-
site shores of the Atlantic, and along the coasts of the United
States, on the contrary, it is the east wind which produces this
effect. It is by south winds that the waters of the Mediterra-
nean are accumulated in the ports of Genoa, Toulon, and Mar-
seilles, and by north winds in those of Algiers, Bougie, and
Tunis. These facts are not disputed, nor do they admit of be-
ing called in question. It only remains to determine the value
of the accidental changes of level which winds may produce.

Franklin relates that, in an extensive piece of water three
leagues broad, and about three English feet in depth, a strong
wind caused the whole of one of the sides to become dry, while
it raised the water on the opposite side three feet above its for-
mer level, the depth being six feet instead of three, Irr our own
seas, I do not think that it will be necessary, in general, to state
a higher number than this as the maximum effect produced by
the most violent tempests.*

The Trades are constant winds, but their strength is very mo-

• Places are mentioned in the Mediterranean where gusts of the south-
west winds (named the Labeschades) have raised the waters seven metres
above their ordinary level ; but this effect was purely local.

Hy4rographi^y and the Ari qf Navigaiwrt, 'W

derate. The deviations from a uniform level which they can
occasion ought hkewise to be inconsiderable. But it seems diffi-
cult to believe, that the vertical iall of a metre, for example, or
^ven two metres, can produce currents which do not entirely
disappear after a passage of many hundred leagues.

I have stated that the trade-winds, on account of their want
of intensity, seem but little likely to produce any considerable
swelling in the waters of the ocean. I will even go further than
this, and prove that, in point of fact, the seas from which cur-
rents appear to emanate, are exactly, or very nearly, of the same
level as those which the currents traverse.

It has been indisputably proved by M. Lepere, in the obser^
vations made during the Egyptian expedition, that the level of
the Mediterranean, near Alexandria, is lower by 8% 1 than
the low water-level of the Red Sea near Suez, and 9™, 9 than
the high water leveL

This is certainly a very great difference of level between two
seas which may be considered as communicating with each other ;
for, on the one hand, the Mediterranean opens into the Atlantic
by the Straits of Gibraltar ; on the other, the Red Sea opens
into the Indian Ocean by the Straits of Babelmandel ; and, in
the third place, the Atlantic and Indian Ocean become blended
with each other at the Cape of Good Hope. It is very far
from my intention to depreciate what is curious or interesting
in such a result as this ; but I must be allowed to say, that it
throws no light on the disputed question of currents, for, to ren-
der the explanation admissible, there ought to be a sensible diffe-
rence between the level of two contiguous seas, between that
from which the current issues, and that into which it flows.

Does not precisely such a difference as this, it may be asked,
exist between the Mexican Sea, in which the Gulf Stream ori-
ginates, and the part of the Atlantic Ocean which washes the
eastern side of the Floridas and Georgia ?

The inhabitants of the Isthmus of Panama believe, but with-
out proof, that the South Sea is higher than the Atlantic Ocean.
Franklin, Rennel, &c. likewise admit a difference of elevation,
but in a contrary sense. M. de Humboldt confirmed this latter
opinion by some barometrical observations made at Cumana,
Carthagena, and Vera Cruz, compared with others made at

46 Questions for Solution relating to Meteorohs^y,

Acapulco and Callao. At the three places first mentioned, the
waters appeared to him to be three metres above the level of the
South Sea, as taken on the western shores of Mexico and Peru*
For as no one can doubt that the general mass of the South-
ern and Atlantic Oceans are of the same level ; that portion
of the latter near the Antilles, and that which is inclosed in the
Gulf of Mexico will thus form a local elevation or intumescence
of three metres.

Before citing a work which does not confirm this result, I
ought to mention that my illustrious friend has himself remark-
ed, with his usual caution, that his observations were not suffi-
ciently numerous to establish the fact of so small a difference of
level without any doubt.

Two engineers not long since crossed America at its narrow-
est point, in order to settle definitively the relative position of the
two oceans. We may add that their object was not purely of a
scientific nature, but had a direct reference to one of the grand-
est problems which commerce ever proposed, the possibility of
^ a communication between the Atlantic and South Seas, across
the Isthmus of Panama. Such was the object of the investiga-
tion, the results of which I am about to state, and which was
intrusted by General Bolivar to Mr Lloyd, an English engineer,
and a Swedish captain named Palmare.

The date of this examination is 1828 and 1829, and it was
made by means of one of Carey's levels. The point of de-
parture is at Panama, on the Pacific Ocean, the level of the
highest tides of the equinox corresponding to the third day of
the full or of the new moon. Its other extremity is a place
named Bruja, to which the influence of the tide extends. Bruja
is on the Chagres, about twelve miles (five leagues) from the
place where that river discharges itself into the sea of the An-
tilles.

At Panama, the mean difference of the level between high
and low water, during strong tides, is 21.2 English feet. At
Chagres, on the Atlantic, this difference does not exceed 1.1 feet.

By thus assuming, in each place, for the mean level of the
ocean, a surffice equally remote from the successive levels of the
high and low sea, it follows, from the examination of Messrs
Lloyd and Palmare :

Hydrography, and the Art of Navigation. 4&

1*^, That the mean level of the Pacific Ocean, at Panama, is
from 3,52 English feet (l*",!) higher than the mean level of
the Atlantic Ocean at Chagres ;

^dy That at the moment of high tide, the ocean on the west-
ern side of the isthmus, is from 13.55 feet (4™,! 3) higher than
on the western side.

3(/, That at the moment of low water, on the same coasts, the
Pacific Ocean, on the contrary, is lower than the Atlantic 6.51
feet (l'",98).

These observations seem, then, to confirm the opinion long
since adopted, that the mean level of the South Sea is more ele-
vated than the mean level of the Atlantic Ocean ; but the differ-
ence, instead of being enormous, as was supposed, is only eleven
decimetres. It may even be allowed us to suppose, without in-
justice to the merits of Messrs Lloyd and Palmare, that, in carry-
ing on their operations in a wild country environed with diffi-
culties ; in traversing a line, the total extent of which, including
sinuosities, is eighty-two miles (33 leagues), and that, in taking
levels at 935 stations, they may have erred to the small extent
of a metre. From this it follows, that there is nothing to proVe
that a sensible difference exists between the mean levels of the
tvvo great seas which communicate with each other by the Straits
of Magellan and Cape Horn. *

The work of Messrs Lloyd and Palmare, in so far as it applies
to the explanation of the rapid current which precipitates itself
from the Gulf of Mexico into the ocean by the Straits of Bahama^
advances as a hypothesis that the South Sea and Atlantic Oceans,
viewed as a whole, form a surface of the same level. We will
escape from this difficulty by relating the results of some obser-
vations made in Florida a few years since by the French officers
appointed by the American Congress to survey the line of a
canal designed to unite the river St Marie, on the Atlantic, with
the bay of Appalachicola, on the Gulf of Mexico.

• If, after the leanied memoirs of M. de Humboldt, it is still necessarj
to return to the truly astonishing depression that the Cordillera of America
presents in the Isthmus of Panama, before again assuming its full majesty in
Mexico, I would remark that the most elevated point of the transverse line
levelled by Messrs Lloyd and Falmare, is only 633 English feet above the
level of the sea.

VOL. XXI. NO. XLI. — JULY 1836. D

BO Questions Jbr Solution relating to Meteorology/,

According to the first calculation of measurements, the low
tide in the Gulf of Mexico would be higher than the low tide of
the Atlantic, by about 1™,14 (3 feet, 52). A second calcula-
tion gives a similar difference between the two low tides of about
0™,85 (2 feet, 63). The mean is 1"^,00 (3 feet, 08).

But even this slight inequality of level is greater than the real
one. In fact, when we compare two seas subject to tides, it is
evidently the mean levels, the points, that is to say, equally re-
mote from the high and low seas, that ought to serve as data.
In this instance, although I can perceive no cause for it, the
comparison is made between two low seas. In order to state the
matter accurately, therefore, it is necessary to elevate the point
of comparison taken in the Gulf of Mexico to half the height
of the tide observed in that gulf. The same thing must be done
in regard to the eastern or Atlantic side of the Floridas. In the
gulf, near the point where the level is terminated, the tide does
not rise more than C^jS. On the other side of the Floridas,
towards the mouth of the river St Marie, the tide is about 2'",0.
The low tide, therefore, is 0™,8 more removed from the mean
tide at St Marie than in the gulf. If, then, the mean levels are
referred to, as must be done to obtain the real result, instead of
l'",0, it will be found that the difference of the level of the two
seas is I'^jO less 0™,80 ; that is to say 0"",2 (7i inches.)

This quantity is evidently within the limits which ought to be
assigned to the errors capable of being made in observations
embracing the whole breadth of the Floridas. But even though
the difference alleged were real, it may be doubted whether any
one would be inclined to regard it as a sufficient explanation of
the cause of a current which, issuing from the Straits of Bahama,
at the rate of no less than five miles an hour (2 leagues), con-
tinues its progress into the very middle of the Atlantic, nearly
in a straight line, to a distance of 500 leagues, without having its
rapidity abated during the whole of that course.

Let us now consider the Mediterranean. Here the alleged
lowness of the level, the presumed cause of the current flowing
from the ocean to the Straits of Gibraltar, is said to be the re-
sult of an enormous annual evaporation, which the mass of wa-
ters contributed by the Nile, Rhone, Po, &c. are insufficient to
compensate. Direct and demonstrative proofs of this want of

Hydrography^ and the Art of Navigation. 61

compensation, are, it is true, completely wanting. In the ab-
sence of these, a new form will be immediately given to the ar-
gument, and it will be said (which is in reaHty the case), that in
summer, at equal latitudes, the waters of the Mediterranean are
from 3^ to 3°5 Cent, (about 6° Fahr.) warmer than those of the
oceaD, from which it inevitably follows that the first undergo
more evaporation than the others, and that nothing more is re-
quired to explain the current of the strait.

And this, it must be confessed, would be sufficient, if the
cause indicated were to produce a very sensible difference of level
in the two seas. Thus, whatever may have been said of it, the
problem will be found to be reduced to one of numbers, or to a
question of facts. It 'must be found out, either by calculation
or experiment, to what extent the Atlantic Ocean is higher than
the Mediterranean. The calculation, I have already stated,
will be difficult to be made with precision, owing to the want of
sufficient data. With regard to the experiment, the results of
that which I am about to present, seem to me calculated to sa-
tisfy the most scrupulous minds.

Delambre found the direct means of inquiring into the com-
parative level of the two seas, by the great chain of triangles
on the meridian of France, which extended from Dunkirk
as far as Barcelona. The triangles comprehended between
Rhodes and the Mediterranean, affiarded him for the vertical
height of that town, a result which agreed to a fraction of a
metre with the height of the ocean, as deduced from that por-
tion of the chain placed between Rhodes and Dunkirk.

It has been stated in opposition to this view, that the obser-
vations from which it was deduced, were not always made in
favourable circumstances; that it is necessary they should be
frequently repeated before they could be assumed as proving a
difference of level; and that, moreover, the calculations had
neither been made with sufficient care, nor on a plan sufficiently
accurate. These objections are not without weight. The offi-
cers of the body of geographical engineers have likewise endea-
voured to take advantage of the chains of triangles of the first
order, drawn in different directions, which cover the whole sur-
face of France, to submit the question of the respective levels
of the two seas to a new examination. M. Delcros, among

d2

52 Questions Jor Solution relating to Meteorology,

others, has devoted himself to this subject, and made extensive
investigations. These, however, are still in MS., and I regret
that I am unable to state the results. Besides this, the obser-
vations which M. Coraboeuf presented to the Academy of
Sciences are as directly to the point as could be desired, and
were conducted with a precision which left nothing to be de-
sired.

This operation, carried on along the southern frontier of
France, during the years 1825, 1826, and 1827, embraces, in
the direction of the shortest distance, all the interval compre-
hended between the Ocean and the Mediterranean. Forty-five
triangles of the first order, many of which have their summits
on the highest points of the Pyrenees, join the fort of Sacoa,
near St Jean de Luz, at different points of the plain of Perpig-
nan, the elevation of which above the sea is so small as to be
reduced to two secondary triangles. All the angles have been
measured by M. Gambey's repeating circles, and by three series
of repetitions at the least. The same is the case with the ze-
nithal distances. Care has been taken, besides, to make these
observations only between 10 o'clock in the morning and 3 or 4
in the afternoon, in order to avoid the effects of the irregular
refractions, which appear near the horizon some hours after the
sun has risen, and a few hours before setting. The extent of
the atmospheric refraction, between each couple of stations, has
been deduced from a comparison of the reciprocal distances to
the zenith. As assistants in these important operations, M. Co-
raboeuf had Captain Peytier and Lieutenants Hossard and Testu
of the Geographical Engineers.

The station of the Crabere occupies nearly the middle of the in-
terval which separates the ocean from the Mediterranean. The
eastern part of the chain of triangles has served to determine its
height above the Mediterranean ; the other part has afforded
this same height above the ocean. It is necessary to remark,
that the calculations can be made by a multitude of distinct
combinations, among which M. Coraboeuf has made choice of
three. He has ascended, in the first place, from the ocean and
the Mediterranean to the Crabere, passing by the only series of
summits of triangles which limit the chain towards the south.
In the next place, by choosing exclusively the northern sum-

Hydrography^ and the Art of Navigation. 53

mits ; and, lastly, by the diagonal directions, that is to say, by
going alternately from a northern summit to a southern one.
The following is the result of these various combinations : —

H*IOHTOK CrABERK. |

On the Medi-
terranean.

On the Ocean.

Diff.

Direction of the southern summits, .
Direction of the northern summits, .
First direction by diagonals.
Second direction by diagonals, .

2633m 37
2633' ', 99
2633 ,87
2632 ,79

2632'", 95

2632 , 07

2633 , 61
2632 , 49

On>, 42
1 ,92
,26
,30

Mean,

2633 , 50

2632 ,77

,73

The mean difference, 0™,73 (2 feet 3 inches), is too small,
particularly when we recollect the extent of the line which was
levelled, to prevent us from concluding that, when in a state of
repose, the waters of the ocean, and those of the Mediterranean,
form a surface of the same level. At all events, U can scarcely
be doubted that if any difference in this respect exist, it is too
small to be appreciated.

In this article I wish merely to prove that the subject of cur-
rents is far from being exhausted ; that differences of level, to
which hydrographers have recourse for an explanation of them,
are either completely nugatory, or insignificant; that there is
still room for further investigation. This object I conceive m}'-
self to have attained. I shall still, however, add a few reflec-
tions.

The theory of currents has made little progress hitherto, be-
cause those phenomena have chiefly been considered which ap-
pear at the surface of the sea. Currents produced by difference
of saltness and temperature exist at all depths. There are cur-
rents, for example, in contact with the very bed of the sea,
which transport the cold waters of the polar zones as far as the
equator. Near the poles these waters move like the solid part
of the earth which supports them, at a very slow rate, from west
to east. As they pass by degrees to temperate and warm re-
gions, they arrive at greater parallels of the earth, which hence-
forth move quicker than they ; hence relative currents directed
from the east to the west, the size of which is equal to that of
the polar currents.

54 Questions Jbr Solution relating to Meteorology,

It is, if I am not deceived, by placing them in this point of
view; by descending, in imagination, to the profoundest depths
of the ocean ; and by applying to the sea the theory which has
already given such a satisfactory explanation of the trade-winds,
that we shall succeed in throwing light on the subject which has
just occupied us. It will thus, in my opinion, be equally possi-
ble to conceive how currents of inconsiderable rapidity cross such
immense extent of sea ; how they are reflected and changed in
their course, while yet at a distance, by the sides of continents
and islands; and how they turn aside on approaching banks,
such as those of Agullas or Terra-neuva, above which there is
not less than sixty fathoms of water !

JSea of Weeds. — Among the phenomena of the ocean, which,
notwithstanding their antiquity, may yet become the subject of
curious investigation, I should be inclined to place that of the
Sea of Plants or the Sea of Weeds.

These names are now applied to a zone of the Atlantic Ocean
situated to the west of the Azores. This zone, on an average,
is from forty to fifty leagues in width ; its extent in latitude is
^5°; the space which it occupies being nearly equal in ex-
tent to the surface of France. It is entirely covered with plants
\Fucns natans). The Portuguese call it Mar de Sargasso ; Ovi-
edo, Praderias de Yerva (Prairies). In 1492, the companions
of Christopher Columbus were greatly alarmed by it, for they
conceived that they had reached the remotest limits of the na-
vigable ocean, and expected to be stopped by the sea-weed, as
their fabulous St Barandan had formerly been by the ice of the
Polar Regions.

By examining a multitude of observations on the subject, de-
posited in the archives of the English Admiralty, in order to
determine the hmits of the Sea of Sargasso, Major Rennel
found that this great bank of fucus has undergone no change of
place, between the years 1776 and 1819, either in longitude or
latitude. This remarkable constancy in situation, M. Humboldt
has shewn to have existed as far back as the end of the fifteenth
century, in his remarks on the observations made by Columbus.

Three different explanations have been advanced to account
for the existence of this sea of Fucus natans. Some are of opi-

Hydrography.^ and the Art of Ncuvi^ution. 55

nion that there are, in these latitudes, numerous banks in the
bottom of the ocean on which the fuci grow, and from which
they are accidentally detached ; others, that these plants vege-
tate, and develope themselves even on the surface of the water ;
but the opinion most generally received is, that the Sea of Weeds
is the place where the Gulf-Stream continually deposits the plants
with which it becomes charged on issuing from the Gulf of
Mexico.

This last mentioned hypothesis has been adopted by Major
Rennel, although it is very far from explaining why a great
proportion of the floating weeds in the sea of Sargasso are, in-
stead of being faded or decayed, in a state of great freshness.
Indeed, English navigators never fail, when they speak of these
regions, to mention the Jresh weed^ and weed much decayed*
Christopher Columbus himself, as M. de Humboldt has remark-
ed, was likewise struck with the mixture of yerba muy vieja y
otra muyjresca.

The floating fuci of the sea of Sargasso are always destitute
of roots and fruit. If we suppose them to be developed in the
same region where they are found, we must regard them, as M.
Meyer has done, as similar to fresh- water algae,' many of which
multiply only by new branches. It will likewise remain to be
explained by what means it is that the waters over such a great
extent of sea escape so completely from the action of winds and
currents, that the lapse of several ages has not dispersed the
plants which were found collected there in the end of the fif-
teenth century, when the galleys of Columbus ploughed it for
the first time.

It doubtless appears more natural to suppose, that, as the
winds and currents by degrees draw the floating fuci beyond
the ordinary limits of die Sea of Plants, their place at the sur-
face is occupied by others detached from the bottom. Accord-
ing to this hypothesis the plants are stationary only in appear-
ance ; the sea will always appear equally covered above the
region which nourishes them, but the indi\ddual8: will be con-
tinually renewed.

What, then, is necessary at the present time to throw ligliton
this curious point of physics ? A few very simple experiments,
which,, however,, are still wannn:^ to science : Soundings made

56 Questions Jbr Solution relating to Meteorology,

along the edges, and towards the centre of the sea of Sargasso,
with the necessary length of line.

, Temperature of Currents. — Every one is acquainted with the
works of Franklin, Blagden, Jonathan WiUiams, M. de Hum-
boldt, and Captain Sabine, on the Gulf- Stream. No one now
doubts that this Gulf-Stream is an equinoctial current, which,
after having made the circuit of the Gulf of Mexico, and issued
from the Straits of Bahama, moves from south-west to north-
east, at a certain distance from the coast of the United States,
retaining all the time, like a stream of warm water, a greater or
Jess degree of the temperature it had acquired between the tro-
pics.. This current divides into two branches. One of these
visits the coasts of Ireland, Orkney, Shetland, and Norway,
having the effect, it is said, of moderating the climate : the other
gradually describes a curve, returns by its former route, cross-
ing the AiXdiiiiic Jrom north to south, usually to the west of the
Azores, and sometimes at no great distance from the coasts of
Spain and Portugal. After a very long circuit, its waters again
join the equinoctial current from which they issued.

Along the coast of America, the position, breadth and tem-
perature of the Gulf-Stream have been so well determined under
each latitude, that a work has been published, without any ap-
pearance of empiricism, under the title of Thermometrical No-
vigation, for the use of navigators in these latitudes. It is very
desirable that the returning branch should be known with the
same certainty. Its excess of temperature almost disappears
when it reaches the parallel of Gibraltar, and it can be accu-
rately determined only by the mean of a great number of obser-
vations. The officers of the Bonite will greatly facilitate this
investigation, if they determine the temperature of the ocean
every half hour, and from the meridian of Cadiz, as far as that
of the most western of the Canaries, with the precision of tenths
of a degree.

We have just spoken of a current of warm water ; our navi-
gators, on the other hand, meet with a current of cold water
along the coasts of Chili and Peru. This current, after leaving
the parallel of Chiloe, moves rapidly from south to north, and
conveys, as far as the parallel of Cape Blanc, the cold water of

Hydrography, and the Art of' Navigation. 57

the vicinity of the southern pole. The temperature of this cur-
rent was first noticed by M. de Humboldt, and it has been ex-
amined with very particular care during the voyage of the Co-
quille. The frequent observations on the temperature of the
ocean which the officers of the Bonite will not fail to make be-
tween Cape Horn and the equator, will serve to extend or com-
plete the important results obtained by their predecessors, espe-
cially by Captain Duperrey.

Major Rennel has described, with minute attention, the cur-
rent which emanates from the south-east coast of Africa, and runs
along the south bank of Agullas. According to the observations
of Mr John Davy, the temperature of this current is from 4° to
5° Cent. (7° to 9° Fahr.) higher than that of the neighbouring seas.
This high temperature is more deserving of the attention of na-
vigators, from its being supposed to be the immediate cause of
the cloud of vapour called the Tahle-cloth, which always en-
velopes the summit of the Table Mountain, whenever the wind
blows from the south-east.

Temperature of the Sea at great depths, — It is not to be ex-
pected that a vessel such as the Bonite, dispatched on a special
mission to the most distant quarter of the globe, will ever de-
lay its progress for the express purpose of engaging in physical
experiments. At the same time, when hours, and even entire
days of dead calm are to be expected, especially when it is ne-
cessary to cross the line frequently, we conceive that this expe-
dition will act wisely by providing thermometographical and
sounding apparatus, for the purpose of sinking instruments in
safety to the greatest depths of the ocean. There is now very
little doubt that the inferior cold waters of the equinoctial
regions are conveyed thither by submarine currents from the
polar zones ; but even the complete solution of this theoretical
point, will be far from depriving the observations we now re-
commend of their interest. Who does not see, for example,
that the depth at which the maximum of cold is found, and we
may even say such and such differences of temperature, must
depend, in every latitude, in a very direct manner, on the total
depth of the ocean ; so that we may expect that the latter may

58 Questions Jbr Solution relating to Meteorology,

sooner or later be deduced from the value of thermometrical
soundings !

Temperature of Shoals. — Jonathan Williams first made us
acquainted with the fact, that water is colder on shoals than in
the open sea. MM. de Humboldt and John Davy confirmed
the discovery of the American observer. Sir Humphry Davy
attributed this curious phenomenon, not to submarine currents,
which, when arrested in their course, rise along the sides of
banks and glide to the surface, but to radiation. By means of
radiation, especially when the sky is clear, the superior beds of
the ocean ought certainly to be greatly cooled ; but every de-
gree of cold, except in the polar regions, where the temperature
of the sea is near zero, occasions an increase of density, and a
descending movement in the beds cooled. Suppose an ocean
without bottom, the beds in question sink to a great distance
from the surface, and must slightly modify the temperature;
but when the same causes operate on shallow water, the cooled
beds accumulate, and their influence must then become very
perceptible.

Whatever may be in this explanation, every one will perceive
how much the art of navigation is interested in verifying the fact
announced by Jonathan WiUiams, which some recent obser-
vations seem to contradict ; how eagerly also meteorologists
will receive the comparative measurements of the temperature
of superficial waters in the open sea and above sand-banks ; and,
in particular, how desirable it is to determine by means of the
thermometograph, the temperature of the bed of water which
rests immediately on the surface of the shoals themselves.

Height of Waves. — The young officers of the Bonite will
probably be greatly surprised if we assure them that none of
their predecessors have fully answered the following questions :
What is the greatest height of waves during tempests ? What
are their greatest transverse dimensions? What is the rate of
their progress ?

Observers have been usually satisfied with forming an esti-
mate of the height. But, in order to shew how erroneous such es-
timations may be, and the influence which the imagination exer-

Hydrography^ and the Art of Navigation, 9t^

cises in such matters, we may state, that navigators equally de->
serving of confidence, have assigned as the greatest height of
waves, in some instances Jive metres, and in others thirty-three.
What science now requires is not rude estimates, but actual
measurements, of what it is possible to appreciate the exact nu-
merical value.

These measurements, we are aware, are attended with great
difficulties ; these, however, are not insurmountable, and, at all
events, the question is of too great interest to justify any hesi-
tation about the degree of exertion necessary to solve it. We
have no doubt that our young fellow-countrymen will them-
selves, upon reflection, devise some means for performing the
operation which we require of their zeal ; but a few brief con-
siderations may assist in guiding them.

Let us suppose, for a moment, that the waves of the ocean
are petrified and immovable ; what, in that case, would be neces-
sary to be done in a vessel likewise stationary, and placed in the
trough of one of the waves, in order to measure the real height,
— to determine the vertical distance of the crest of the wave
and the trough ? An observer would gradually ascend the
mast, and stop at the point where the visual horizontal line,
parting from his eye, seemed to touch the crest in question ; the
vertical height of the eye above the surface on which the vessel
was floating, would be the height required. This operation,
then, it would be necessary to attempt in the midst of all the
commotions and disorders of a tempest.

In a vessel at rest, as long as the observer does not change his
place, the elevation of his eye above the sea remains uniform,
and can be very easily determined. In a vessel tossed by the
waves, the rolling and pitching incline the masts sometimes to
one side, sometimes to another. The height of the points of
the top-masts varies incessantly, and the officer who has taken
his station on the mast cannot ascertain the value of his vertical
line, unless by the assistance of a second person placed on tlie
deck, whose object it ought to be to follow the movements of
the mast. If one Hmit their pretensions to ascertain this line
within a third of a metre, for example, the problem appears to-
us completely solved, particularly if the moments choseff for

60 Questions Jbr Solution relating to Meteorology,

observation are those when the vessel is nearly in her natural
position, for then she is precisely in the trough of the wave.

It now remains to discover the means of determining whether
the visual line resting on the summit of a wave be horizontal.

The crests of two contiguous waves are of the same height
above the intermediate hollow. A visual horizontal line leaving
the eye of the observer, when the vessel is in the trough, I sup-
pose to be directed to the summit of ^the approaching wave ; if
this line be prolonged on the opposite side, it will likewise touch
the summit merely of the wave already past. This last condi-
tion is necessary, and is sufficient to establish the horizontality
of the first visual line ; or with the instrument known under the
name of the Dip-sector, having its ordinary circles provided with
an additional mirror, there may be seen at the same time, in the
same glass, and in the same part of the field, two images, situ-
ate at the horizon, .one before, the other behind. The dip-sector,
then, will shew to the observer, as he gradually ascends the mast,
at what instant his eye reaches the horizontal plane touching the
crests of two neighbouring waves.

We have supposed this observation to be made with all the
precision that nautical instruments admit of. The operation
will be more simple, and sometimes sufficiently exact, if the ob-
server merely determine, with the naked eye, to what height he
could ascend the mast, without ever perceiving, when the ves-
sel is sunk in the trough, any other wave than the nearest
of those approaching or receding. In this way the observa-
tion may be made by any one, and even during the severest tem-
pests, that is to say, in circumstances where the use of reflecting
instruments is attended with some difficulties, and when, more-
over, perhaps no one but a sailor could venture with impunity
to climb the mast.

The transverse dimensions of waves are easily determined, by
comparing them with the length of the vessel as she passes
through them ; their rapidity is measured by well-known means.
We have, therefore, in concluding the article, again to recom-
mend these subjects of inquiry to the attention of the conjmander
of the Bonite.

Visibility of Shoals. -^The bottom of the sea at a given dis-
tance from a vessel, is more distinctly seen in proportion as the

Hyarography, and the Art of Navigation, 61

observer is elevated above the surface of the water : thus, when
an experienced captain navigates an unknown sea filled with
shoals, he sometimes places himself on the summit of the mast,
in order that he may direct his vessel with greater security.

The fact appears to us so well established, that we have no-
thing to require of our young navigators regarding it in a prac-
tical point of view ; but, by following the indications which we
shall here point out, they may perhaps ascertain the cause of a
phenomenon which affects them so nearly, and thence deduce more
satisfactory means than casual observation has hitherto taught
them to en) ploy, for the purpose of detecting the situation of
shoals.

When a pencil of light falls on a diaphanous surface, what-
ever may be its nature, a portion passes through it, and another
portion is reflected. What is reflected is more intense in pro-
portion to the smallness of the angle formed by the incident ray
with the surface. This photometrical law is not less applicable
to the rays which emanate from a rare medium, and meet the
surface of a dense body, than to those which, moving in a
dense body, fall on the surface of separation of that body and
of the rare contiguous medium.

This being the case, let us suppose that an observer on ship-
board wishes to perceive a shoal at a little distance — a subma-
rine shoal, situate at thirty metres of horizontal distance, for ex-
ample. If his eye is about the height of a metre above the sea,
the visual line by which the light emanating from the shoal can
reach him after issuing from the water, will form a very small
angle with the surface of the fluid ; if the eye, on the contrary,
is very much elevated, suppose thirty metres, he will see the
slioal under an angle of 45°. But the interior angle of inci-
dence, corresponding to the small angle of emergence, is evi-
dently less open than that which corresponds to the emergence
of 45°. Under small angles, as has^ been seen, the strongest
reflections take place; the observer, therefore, will receive k
more considerable portion of the light which emanates from the
shoal the higher he happens to be placed.

The rays emanating from the submarine shoal are not the
only ones that reach the eye of the observer. In the same di-
rection, and confounded with them, are rays of atmospheric light

*V^ Questions Jbr Solution relating to Meteorology,

reflected exteriorly from the surface of the sea. If the latter
were sixty times more intense than the former, they would to-
tally conceal the effect. The shoal would not even be suspect-
ed, for it has been proved by the experiments of Bouguer, often
repeated since, that the most experienced eye is not sensible of
an augmentation of light of -^-q. If there be a small proportion
between these two lights, the appearance of the shoal will not be
entirely lost ; but it will be very feeble. When it is remember-
ed that the atmospheric rays sent to the eye from the sea, have
a greater degree of splendour if reflected under an acute angle,
every one will perceive that two diff*erent causes concur to ren-
der a submarine object less apparent in proportion as the visual
line approaches the surface of the sea, namely, on the one hand,
the progressive and real weakness of the rays emanating from
the object, which have to form its image in the eye ; and, on
the other, a rapid augmentation in the intensity of the light re-
flected from the exterior surface of the waters, or rather, if I
may be allowed the expression, in the luminous curtain to
which the rays issuing from the shoal must communicate their

light.

On the supposition that the comparative intensities of the two
superimposed pencils are, as every thing leads us to believe, the
only cause of the phenomenon which we are now analyzing,
we have it in our power to point out a better and more easy
means of detecting submarine shoals, than has been hitherto fol-
lowed. This means is very simple ; it consists of looking at the
sea, not with the naked eye, but through a plate of tourmaline
cut parallel to the edges of the prism, and placed before the
pupil in a certain position. A few words will render the mode
in which the crystalline plate acts evident.

Let us assume that the visual line is inclined to the surface
of the sea 37°. The light which is reflected from the outer sur-
face of the sea under this angle, is completely polarized. Po-
larized light, as every natural philosopher knows, does not tra-
verse plates of tourmaline suitably placed. A plate of tourma-
line, then, may keep off entirely the rays reflected by the water,
which, in the direction of the visual line, were mingled with the
light emanating from the shoal, either obstructing it entirely, or
at least greatly weakening it. When this effect is produced, the

Hydrography^ and the Art of'JSfavtgntioiu 63

eye placed behind the plate, will receive only one kind of rays,
those which emanate from submarine objects ; instead of the two
superimposed images, only a single image will be formed on the
retina ; and the visibility of the object which this image repre-
sents will thus be found greatly facilitated.

The entire and absolute obstruction of the light reflected from
the surface of the water, cannot possibly take place but under
an angle of 37°, because it is under this angle alone that it is
completely polarised ; but under angles from 10° to 12° greater
or less than 37°, the number of polarised rays which the tour-
maline can arrest, is still so considerable, that the same means of
observation cannot fail to be attended with very advantageous
results.

By engaging in the trials which we now propose to them, the
officers of the Bonite will throw light on a curious question of
photometry ; they will probably confer on navigation a means of
observation which may prevent many shipwrecks; and by in-
troducing polarization into the nautical art, they will afford an
additional proof of what those individuals expose themselves to,
who unceasingly collect experiments and theories without any
practical application of them, meeting every remonstrance with
a contemptuous cui bono ?

Water-Spouts. — Has electricity any influence in producing
water-spouts ? A distinct and categorical answer to this question
would be possessed of great interest. The officers of the Bonite
ought therefore to attempt to discover, when this phenomenon
presents itself to them, whether it produces thunder and lights
ning.

Depressions of the Horizon, — The rather distinctly defined
blue line, forming the apparent separation between the sky and
the sea, to which sailors refer the position of the stars, is not m
the mathematical horizon ; but the degree at which it appears
below it, and which is called the depressioji, may be calculated
exactly, since it depends merely on the height of the observer's
eye, and the dimensions of the earth. It is unfortunately not
so easy to appreciate the effects of atmospheric refractions. It
must even be said, that in the calculations of the tables of de-
pression usually employed, the meati refraction only is taken
into account, relative to a certain state of the thermometer and

64 Questions Jhr Solution relating to Meteorology,

barometer. Officers of great skill, Captain Basil Hall, Captain
Parry, and Captain Gauttier, have determined by observations,
the errors to which navigators are exposed by following the
common rule. It was sufficient for them to measure, either
with the dip-sector of Wollaston, or with the ordinary instru-
ments furnished with an additional mirror, and that in the most
varied states of the atmosphere, the angular distance of one
point of the horizon from the point diametrically opposite. Ad-
mitting, as we may be nearly at all times allowed to do, that
the state of the air and of the sea are the same all around the
observer, the difference of the distance measured at 180'', is evi-
dently double the real depression of the horizon. The half of
difference, compared to the depression of the tables, gives,
therefore, the possible error of every angular observation of
height made at sea.

The positive and negative errors observed by Captain Parry
in the northern regions, have all been comprised bet\^een + 59"
and — 33." In the Chinese and East Indian seas. Captain Hall
found the deviations greater ; from + 1' 91' to — 9! 58". Final-
ly, Captain Gauttier, in the Mediterranean and Black Seas,
gives a still greater length, from + 3' 35" to — V 49". If it be
recollected that the variation of a single minute in latitude near-
ly corresponds to a deviation of 2000 metres on the globe, every
one will acknowledge how deserving of attention is the investi-
gation which we have just mentioned.

By examining with care all the observations of MM. Gaut-
tier, Basil Hall, and Parry, we come to the conclusion, that the
error of the calcuLx\ted depression is not positive, and that
this depression does not exceed that ohsei'ved^ except to the
amount that the temperature of the air is higher than the tem-
perature of the water.

With regard to the negative errors, they present themselves
indiscriminately in all the comparative thermometrical states of
the sea and atmosphere, without the possibility of attributing
these anomalies to any apparent cause, and, in particular, to the
degree of the hygrometer.

MISCELLANEOUS OBSERVATIONS.

Rising of the Coast of Chili. — In the month of November

Hydrography^ and the Art of Navigation* 65

1822, after the earthquake which overturned the towns of Val-
paraiso, Quillota, &c., in ChiH, great part of the country was
found to be elevated from one to two metres above its former
level. The earthquakes of 1834 appear to have been still more
severe than that of 1822. It will therefore be of importance to
examine whether they have not in like manner produced a sud-
den rise of the 'country. A beach on which the sea, by the ef-
fect of the tides, never ascends beyond one or two metres
ought to furnish a multitude of appearances, such as " embarca-
deres,"" banks of oysters, muscles, and other shell-fish adhering to
rocks, by means of which any doubt on the subject may be re-
moved. A glance at the localities will do more in this respect,
than the necessarily vague indications which we can furnish here.
We can conceive, however, that we ought to mention the lake
of Quintero, which communicates with the sea, as well fitted to
afford indisputable proofs of changes of level. Recourse should
likewise be had to the hydrographical charts of Vancouver, Ma-
laspina, &c., for it is by no means probable that these risings
would take place on the shore, without the bed of the sea parti-
cipating in them.

Sudden or gradual elevations of the ground appear destin-
ed to perform such an important part in the history of the
earth, that we must particularly invite the officers of the Bonite
to take note of all recent phenomena of this nature that they
meet with, and in an especial manner to direct their attention to
the coast of Peru. *

Earthquakes, — According to an opinion pretty generally en-
tertained in America, earthquakes are more frequent in certain
seasons than in others. If this were fully ascertained to be the
fact, it would be of extreme importance in the physics of the
earth. A complete collection of the journals which have been
published in Chili for twenty years, examined in relation to this
• At the moment when this sheet is going to press, I learn that some Botes
of Captain Fitzroy have just been read before a court-martial met at Porta-
mouth, for the trial of Captain Seymour, of the English frigate Challenger^
shipwrecked on the coast of Chili. These notes, designed to account for the
catastrophe, take notice of the changes which the currents have undergone
near the port of Conception, since the earthquake of February 1836. Cap-
tain Fitzroy likewise states, that the island of SanU Maria has risen 10 Eu-
glish feet.

VOL. XXI. NO. XH.— JULY 1836. E

66 Questions Jbr Solution relating to Meteorologt/, Si-c.

point, would certainly throw some light on the question. We
recommend this object to the commander of the expedition,
whether he may be inclined to perform the task during the voy-
age, or be contented with collecting materials for it.

To adopt popular opinions too hastily, is to run the risk of
introducing into science, to its great injury, a multitude of con-
fused notions, founded on phenomena imperfectly seen and in-
accurately examined ; but to reject these opinions without exa-
mination, is often the occasion of losing an opportunity of ma-
king some important discovery. From this consideration I do
not hesitate to entreat our young countrymen to inquire, during
their stay on the western coast of America, whether the pheno-
mena which are said to have attended the earthquake which de-
stroyed Arica and Saena on the morning of the 18th September
1833, have been observed in any other places. The following
is an account of them by Mr John Reid, an English traveller.

" The continual baying of dogs, and braying of asses, an-
nounced the approach of danger. On the preceding day, the
atmosphere had been of an alarming stillness. With the excep-
tion of a few rare gusts, coming sometimes from one side and
sometimes from another, and which were felt quite as well in
the interior of an apartment as on the outside ; it might be
said that during the whole of the day of September 18th, the
immobility of the air at Saena was complete.

" The shocks had left a great number of empty bottles in the
places which they occupied, but their corks were found scattered
about in all directions.

" None of these empty bottles had been even overturned ;
others that were filled, on the contrary, were thrown out of their
places and broken.

" The varnish which covered a new table belonging to Mr
Reid, became so fluid, that the day after the earthquake the ma-
hogany appeared surrounded with hanging glue.

" Some large jars of earthenware were sunk in the earth and
contained water ; and although the surface of the water was
three or four feet below the mouth of the jars, yet a great part
of the water was thrown out on the surrounding soil.

" At^ Saena it was remarked, that after a shock, whether
slight or severe, all the dogs of the town went to quench their
thirst at the first pool of water they could fall in with."

Dr Graves on tJie Sense of Touch, 67

Declination and Inclination of the Magnetic Needle at
Paris.— On the 9th November 1835, at Ih 8' p. m. we found
that the northern extremity of the magnetic needle pointed to
the west of the astronomical north, 22° 4'. On the 3d July
1835, at 9^. morning the inclination, was 6T 24'.

Obsertations on the Sense of Touch, including an Analysis of
Weber's Works on that subject. * By Dr Graves of Dublin.-f

Weber's experiments on the sense of Touch are extremely in-
teresting and original ; some of them have been already published
in English periodicals, but in so imperfect a manner as to fur-
nish a very inaccurate and incomplete view of their results. If
we touch the skin with the points of a compass one inch asun-
der, while the person so touched shuts his eyes, he at once per-
ceives his skin to be touched in two places. By continually di-
minishing the distance between the two points, we finally arrive
at a degree of approximation where the person feels his skin to
be touched by but one body ; he describes this body, however,
as being a little longer in one direction than another, and it
appears that this longer diameter corresponds with the line of
junction between the two points of the compass. When these
points are brought still nearer together, this inequality in the
diameters is no longer felt, and the person has a defined percep-
tion of being touched by but one body. Now Weber has deter-
mined, by experiment, that the different portions of the surface
of the body vary considerably in accuracy of touch, as measured
by the distance at zohich the points of the coinpass can be still
distinguished from each other ; for it is evident that parts en-
dowed with great power of touch, will continue to give notice of
two points at a distance from each other, so small, that when
examined at the same distance by less sensible portions of the

* De Puhu, Respiratione Audita et Tactu, AnnoioHones Anatomicae et Physio*
hfficae. Auctore Henrico Ernesto Weber. Lipsiaef 1834.

t This interesting Memoir appeared in the March number of the Dublin
Medical Journal, which did not reach Edinburgli until a month after its
Usual time.

£2

68 Dr Graves on the Sense of Touch.

skin, these two points excite but one sensation, and are by the
touch erroneously judged to be but one. Thus the tips of the
fingers and the point of the tongue were found to possess the
most accurate sense of touch, for when the points were dis-
tant but half a Parisian line from each other (counting from the
inner surface of each point), the feeling of the two distant points
existed, and when they were within two-fifths of a line, although
the person seemed to feel but one body, he nevertheless felt it
to be longer in one direction than in another. The dorsum of
the tongue was remarkably less sensible, for if the points placed
m a line parallel to the median were less distant than three lines
from each other, they were not felt to be distant. Few persons
who have not tried similar experiments will he prepared to credit
the announcement of the very great difference which exists hetzveen
the tactile accuracy of different portions of the shifi. On this sub-
ject the observations of Weber are quite novel, and open a new
field for inquiry, not only to the physiologist, but to the practi-
cal physician and surgeon ; for it is obvious that injuries or re-
medies applied to the skin must act with very different degrees
of energy on parts so widely different in tactile sensibility from
each other. I have repeated many of Weber's experiments, and
confirmed his results. A little practice is necessary in order to
accustom ourselves to judge concerning the sensation, compared
as the points of the compass approach each other, and come
within the limits of confusion (a term I have adopted to express
the distance at which they produce the feeling of but one bod}-,
longer, however, in one direction than another). The sensation
imparted is most curious. A few instances will suffice to prove the
extent of the scale through which this limit of confusion ranges,
when the points are placed on the same horizontal line.

Tip of the tongue 1 line. Margin of tongue, one inch from
its tip, 2 hues. Skin on the zygomatic bone, 6 lines. Forehead,
6 lines. Hairy scalp, 8 lines. Middle of back, 12 lines. Near
the upper border of the scapula, 18 lines. Inferior angle of the
scapula, 24} lines. On the loins, 12 fines. Side of abdomen, 12
lines. Anterior surface of arm, 10 lines. Posterior do. 14.
lines. Tips of the fingers, 1 fine. Do. of toes, 3 lines.

The above results were obtained in examining the skin of
others. The followinor, which Weber has arranged in the ascend-

Dr Graves on t?ie Seme of' Touch, 69

ing scale as to the measurement of the limit qfconfusiouy was
taken from experiment on himself. He entitled it " Tabula
graduum subtilitatis tactus in potissimis corporis mei partibus,
quos per minimam distantiam crurum circini corpori impositorum,
qua perpendicularis et horizontalis crurum situs, et intervallum
interpositum sentiri poterat, metitus sum.^ The limit of confu-
sion in the following table is therefore the distance at which the
points of the compass could not only be perceived to be distinct
from each other, but their direction, whether horizontal or per-
pendicular, could be judged of.

Tip of the tongue, ^ line. Inner surface of the ifinger tips,
1 line. Red part of lips, 2 lines. Inner surface of second pha-
lanx of fingers, 2 lines. Outer or third phalanx of do., 3 lines.
Top of nose, 3 lines. Inner side of extremities of metacarpal
bones, 3 lines. Dorsum of the tongue one inch from its point, 4
lines. The portion of the lips which is not red, 4 lines. Edge
of the tongue, one inch from its point, 4 lines. Metacarpal bone
of thumb, 4 lines. Apex hallucis, 5 lines. Skin covering buc-
cinator, 5 lines. Dorsum of second phalanx of fingers, 5 lines.
Palm of the hand, 5 hues. Surface of eyelid, 5 lines. Centre
of hard palate, 6 lines. Anterior surface of zygomatic process,
7 lines. Dorsum of the first phalanx of fingers, 7 lines. Out-
side of extremities of metacarpal bones, 8 lines. Mucous mem-
brane of lips close to the gum, 9 lines. Posteriot surface of its
zygomatic process, 10 lines. Lower part of the forehead, 10
lines. Back part of the heel, 10 lines. Occipital skin, lower part,
12 lines. Back of hand, 14 lines. Neck, beneath lower jaw, 15
lines. Vertex of the scalp, 15 lines. Patella, 16 lines. Skin on
the sacrum, 18 lines. Acromion, 18 lines. Glutaeus, 18 lines.
Superior and posterior surface of forearms, 18 lines. Leg near
the knee and near the foot, 18 lines. Dorsum of foot near toes,
18 lines. Sternum, 20 lines. Dorsal spine over five superior
vertebrae, 24 lines. Cervical spine near occiput, 24 Hnes. Lum-
bar spine, 24 lines. Centre of cervical spine, 30 lines. Centre
of dorsal spine, 80 lines. Middle of the arm where it measures
most in circumference, 30 lines. Do. of the thigh, 30 lines.

This enumeration of relative distances, allowance being made
for all probable inaccuracies in the experimental estimate of
these distances, affords ample matter for reflection ; and fur-

70 Lr Graves on the Sense of Touch.

iiishes abundant proofs, if any were wanting, of the wisest adap
tation of parts to the functions they are called on to discbarge.
Here is no unnecessary expenditure of tactile acumen, but a most
rigid economy of the sense of touch, which is nowhere spread
over surfaces indiscriminately, and without reference to their
other physical qualifications. This great difference was never
before suspected to exist ; it was indeed known that the tops of
the fingers, the tip of the tongue, and some other parts, enjoy
the sense of touch in a pre-eminent degree, and are capable of
judging much more delicately, concerning what they are placed
in contact with, than other portions of the body. This was at-
tributed partly to habit, partly to their shape, and many laid
great stress on the facility with which these extremely moveable
parts could be adapted and applied to bodies undergoing ex-
amination. Now, for the first time, has it been proved by We-
ber, that, quite independently of all these extraneous circum-
stances, the skin itself varies in the intensity of its tactile power ;
and that this arises not from the mere varying thickness of the
epidermis, and general delicacy of conformation in the cuta-
neous tissue, but from an original difference in its organization.
All these facts tend strongly to overturn the common hypothesis,
that the sense of touch is diffused throughout the whole texture
of the skin, and lender it much more probable that it is per-
formed only hf certain small organs, extremely minute, and in
size comparable to points, but differing much in their mode of
distribution, being very crowded together and numerous in some
parts of the ?kin, while in others they are more sparingly pre-
sent, and are, as it were, thinly scattered. On this supposition
alone, we can account for the signal differences in tactile dis-
cernment, which the different portions of the skin exhibit. The
researches of Breschet, to which the attention of the English
public was first drawn, by an able analysis by my friend Dr
Gostello, published in the Dublin Medical Journal for Septem-
ber 1835 ; these researches have rendered it certain, that the
sense of touch is performed by a less simple apparatus than was
generally imagined. M. Breschet considers that the nerve parts
with its neurilema at the derma, as the optic nerve does in en-
tering the sclerotic, and that the projecting papillae take a new
envelope from the outer surface of the derma ; that the mere

Dr Graves on the Sense of Touch. 71

nervous pulp does not, of itself, constitute the sense of touch,
but that, as in the sense of hearing or of sight, there is an appa«
ratus, all the parts of which must be in unison to be perfect.
If any one of the five constituent parts be wanting, touch can-
not be exercised, and the derma, neurilema, and proper epi-
dermic membrane, are to the papilla, what the complicated ap-
paratus of sight and hearing are to the optic and acoustic nerves.
The analogy goes farther, for the optic and acoustic nerves, on
entering the structure of the eye and ear, undergo the same
change as the tactile nerve entering the derma, with this diffe-
rence, that the two former remain in their cavities, where light can
penetrate to the one and sound to the other ; but the nerve of
touch must advance, as it were, to meet impressions. The
following very curious phenomenon is recorded by Weber :—
" If the points of a compass, distant from each other one or two
lines, applied to the cheek, just before the ear, be then moved
successively to several parts of the cheek, we shall find, on ap-
proaching the angle of the mouth, that the points will appear
to recede from each other ; this is produced by the great differ-
ence of tactile power in these parts. It is a general law, that
the more sensitive portions of the skin regard any two points as
farther asunder from each other, than equidistant points appear
to be to a less sensitive portion. The same experiment may be
tried by holding together the extremities of the fore-finger and
thumb, and then passing the tips of both in a line from the ear
to either the upper or the under tip ; as they approach the lat-
ter, they will feel to the check as if they were becoming more
and more distant from each other."

Another fact was observed by Weber — " If the legs of the
compass be applied to two contiguous surfaces, enjoying the
functions of voluntary motion, they will appear to be much
more distant from each other, than when th^y are applied to one
of these surfaces separately. Thus, if the points are distant
half a line, they are not perceived to be distant when applied
to one lip, but when one point is applied to the under lip, and
another to the upper, they are at once felt to be two."

Another very remarkable conclusion announced by Weber
deserves consideration : " Apply the legs of a compass to two
portions of the skin, differing from each other remarkably, either

718 Dr Graves on the Sense of Touch

in structure, in function, or in the use habitually made of them,
and the legs will appear to be more clearly and distinctly felt
than when they are applied to one and the same surface, even
though it be the more sensitive of the two ; thus the legs, when
in contact, one with the inner surface and the other with the red
outer surface of the lips, appeared much more distant from each
other than when they were in contact with the red surface only,
which has much greater tactile powers than the inner surface.
The same observation applies equally to the neighbouring
surface, differing much from each other in tactile power, viz.
the margin and the dorsum of the tongue, the volar and the
dorsal surfaces of the finger-points," &c. One result of Weber's
experiments is of great importance in a physiological point of
view : — " The tactile powers of any part of the skin are not, as is
generally imagined, directly proportioned to its sensibility ; thus
the mammae are easily tickled, and capable, when irritated, of
producing great pain ; in these respects they exceed any portion
of the trunk, and yet the skin of or round the nipples is but
very indifferently endowed with the faculty of touch, properly
so called. Indeed the same remark applies to the arm-pits, the
flanks, the soles of the feet, &c., and all ticklish parts of the skin
in general, as they are possessed of a comparatively slight power
of discriminating objects from each other by means of the touch.
Who was ever made to laugh by tickling the points of his
lingers ? and yet they are possessed of a tactile accuracy far ex-
ceeding that of any other portion of the skin !"

This is a very curious subject of inquiry, and one not yet in-
vestigated. The reason of the matter is sufficiently obvious,
for parts endowed with the greatest tactile acumen are necessa-
rily much exposed, being so placed as to be brought with the
greatest facility into contact with external bodies, consequently, if
so disagreeable a sensation as that arising from tickling were easily
induced by this contact, those parts would be almost useless as
organs of touch. The experiments of Weber, considered with
reference to the researches made by Breschet on the structural
anatomy of the skin, render it extremely probable that the sense
of touch, properly so called, resides in a peculiarly constructed
apparatus, supplied with certain ramifications of the cutaneous
nerves, while the function of sensation, comprising the power of

Dr Graves oji the Sense of Touch, 78

perceiving painful or pleasing impressions, is much more gene-
rally diffused, and is the result of a much simpler organiza*
tion. In fact, although the internal, mucous, fibrous, and serous
surfaces, and the parenchyma of the different organs, are all
capable of becoming actually painful, particularly when inflamed,
yet it is very doubtful whether the sense of touch, properly so
called, is ever exercised by those parts. No foreign substance
is ever distinctly felt by the touch in the stomach and bowels ;
a sensation, painful or pleasing, is indeed excited by some mat-
ters immediately after they are swallowed, but all consciousness
of their presence, by means of the sense of touch, soon ceases,
and it cannot be again recalled by the utmost exertion of the will.
A foreign substance lodged in the alimentary canal, or in the
trachea, may give rise to the greatest possible degree of irrita-
tion ; but though it thus acts upon the nerves of the parts im-
mediately in contact with it, these nerves convey no idea to the
sufferer of the shape or size of the body, or of any other of its
physical qualities, concerning which we receive information
through the medium of the sense of touch.

Webef s observations (pp. 67, 77) on the comparative tactile
energy of the different portions of the trunk of the body, are
extremely curious, and have disclosed a very remarkable diffe-
rence between the sense of touch in the trunk and in the extre-
mities. In the latter, where the points of the compass are placed
across the axis of the limb horizontally, they are much more
accurately distinguished than when they are placed in the longi-
tudinal direction, or parallel to the axis of the limb (vertical), in
other words, the limit of' confusion is much sooner attained in
the vertical than in the horizontal position of the points. Now,
in many parts of the trunk the contrary obtains, and the verti-
cal position is more accurate than the horizontal ; this singular
difference Weber explains by the different manners in which the
nerves supplying the extremities and the trunk are distributed.
The branches of the former generally run nearly parallel to the
axis, while those of the latter pursue in most cases a transverse
course ; all parts of the trunk do not exhibit this difference.
Whether this explanation is or is not admitted, the fact is un-
doubted. Our author next proceeds to shew what* motion,
whether it be of the touching organ or of the body to be touch-
ed, greatly augments the clearness and accuracy of the percep-

74 Dr Graves on the Sense of Touch.

tion, a fact too familiar to require any elaborate illustration. As
to the idea of direction which we derive from the sensation impart-
ed to the skin by any minute substance, he justly observes, that
it is always judged to be perpendicular to the surface of the skin
at the point of contact. Of this there can be no doubt, and here
we have a very striking analogy between the sense of vision and
of touch, for it is a primary law, that rays of light impingent on
the retina always produce a sensation, i. e. are seen in a direction
perpendicular to that point ; it would be well worth while exa-
mining whether the same law of perpendicularity is extended also
to the ear. In the case of the eye this law is strikingly useful, as
it enables many rays, originally diverging from the same luminous
point, all to create a sensation in the same direction, although
in converging they strike the retina from very different direc-
tions; in the eye all these perpendicular lines intersect at a com-
mon point, thence called the centre of visible direction, and this
result derived from the spherical shape of the retina is attended
with the most important consequences. No one has as yet at-
tempted to investigate the question, whether any similar provi-
sion or contrivance exists with regard to the lines of direction,
to which each part of the auditory nerve receiving vibrations re-
fers sound ; any given point of the hearing surface of the acoustic
nerve receives impulses from the vibration essential to this sense,
conveyed either through the fluid of the vestibule and semicircu-
lar canals, or through the solid bone surrounding the cochlea ; the
question arises, whether vibrations excited originally by the sound-
ing body arrive by different routes simultaneously at the same
point of the nerve, so as materially to reinforce and strengthen
each other. Is there in this case any provision made to pre-
vent vibrations, which arrive in different directions, from inter-
fering with each other, with reference to the sensation they pro-
duce? Or are both, as impinging on a common point, referred
to one common direction ? If this were the case, the analogy be-
tween the perceptive properties of the retina and auditory nerve
would be perfect, and nothing w^ould remain to the philosophical
examiner of the mechanism of the sense of hearing but to dis-
cover what relation these lines of common direction bear to the
surface of the auditory nerve, and to each other ; are they, as
in the case of the retina, perpendicular to the nervous surface,

Dr Graves on the Sense of Touch, 'ffc

and in what manner are they so arranged, that, in consequence
of the shape of that surface in the convolutions of the internal
ear, each line of direction resulting from the vibration communi-
cated to any point, may be parallel to the various other lines of
direction which result from vibrations, simultaneously communi-
cated to all other points of the nervous surface?

These are extremely difficult questions, but it is l)y no means
improbable that they may be hereafter satisfactorily resolved.
But, to return to the sense of touch ; in some parts of the surface,
an exception seems to occur to the general rule of perpendicu-
larity ; thus, when a hair of the head is pulled, we can judge
perfectly well of the direction in which it is pulled. The most
obvious explanation of this fact, which refers to the discrimina-
tion of the line of traction to the bulb of the hair, Weber proves
to be erroneous, and he shews that we judge of the direction in
which the hair is pulled, by means of the muscles called into ex-
ertion to counteract the pull, and keep the head steady during
its continuance. If these muscles be not called into play, which
is the case when the head is held steadily by the hands of one
person, while another, by surrounding the point in which the
hair is pulled, with a firm pressure made by the fingers, thus
prevents the least motion in the enclosed portion of the skin,
then no matter in what direction the hair is pulled, the person
cannot judge of it.

Weber's experiments on the faculty the skin possesses of esti-
mating and comparing different pressures made on its surface,
ought not to be altogether passed by in this report. One chap-
ter he entitles, *' De Suhtilitafe Tactus in cognoscendo corpo-
rum pandere.'^'' If both the right and the left hand of the same
individual are supported on cushions, and that he keeps his eyes
shut, while unequal weights are placed one on each hand, he
will, if the difference between the weights is considerable, be
able to tell on which hand the heavier lies ; slight differences of
weight cannot be thus estimated, but they at once become percep-
tible if the hands be raised from the cushions ; the muscles that
now support the weight give great assistance in estimating its force.
Thus we judge of the weight of any heavy body, partly by
the pressure it produces against our surface, but chiefly by the
quantity of muscular force it requires us to use in lifting or sus-

76 Dr Graves oil the Sense of Touch,

taining it. Weber has ascertained that in most men, the left
side of the body and the left extremities enjoy a more accurate
perception of weight than the right, so far as weiglit is estimated
by pressure ; of fourteen different persons experimented on, the
left side of the body and the left extremities were found to be
more sensible of weight, measured by pressure, than the right, in
eleven ; in two the contrary was observed, and in one only no
difference between the sides could be detected. He offers no sa-
tisfactory explanation of this very remarkable and hitherto un-
observed phenomenon, which is obviously of some value as mak-
ing an original difference between the nervous power of the right
extremities and right side of the trunk, as compared with the left,
a difference which favours the idea, now indeed generally admit-
ted, that we cannot explain the circumstance of man being right-
handed and right-footed, except on the hypothesis of an original
difference in the vital powers of the right and left halves of the body.

Weber next proceeds to make some observations, De Subti-
litate T actus in sentiendo colore.

I long ago maintained the opinion, that the perception of heat
and cold is not a mere modification of the sense of touch. I am
glad to find this view of the subject advocated by so high an au-
thority as Lord Brougham, who, in his Discourse on Natural
Theology, p. 3, note, remarks, that " there seems as little reason
for arranging the sense of heat and cold under touch, as for ar-
ranging sight, smell, hearing, and taste, under the same head.""
Experiments made for the purpose of comparing the energy of
this sense in different parts of the body, are attended with ob-
vious difficulties ; thus if the surface of the substance applied to
the body be not exactly of the same extent in two cases, the re-
sult is not to be relied on, for, cateris paribus, a larger body
will feel hotter or colder than a smaller, and that in a very re-
markable degree. Thus, let one vessel contain water heated to
98°, and another water at 104° ; now if the finger be placed in
the latter, and the whole of the other hand be immersed in the
cooler, we shall be led to form a wrong judgment, and will pro-
nounce the water at 98° to be hotter than that at 104° ! In
some cases the same error was made when the difference of tem-
perature amounted to eight degrees, the hotter being at 106°. If
the parts were kept a good while immersed, the person some-
times becomes sensible of his error, and judges rightly.

Dr Graves on the Sense of Touch, TT

Weber has discovered a very remarkable fact, that the left
hand is more sensible of heat or cold than the right in most
persons. Thus, when the hands of a person lying in bed, and
of exactly the same temperature, were plunged each in a sepa-
rate vessel of hot water, the left hand was believed by the per-
son to bo in the hotter medium, even though the water it was in
was really one or two degrees colder than the other. Weber
has rendered it highly probable, that the greater sensibility
which the left hand undoubtedly possesses in perceiving changes
of temperature, is owing to the circumstance of its being cover-
ed, particularly on its palm, by a thinner epidermis, in conse-
quence of being less used. Nothing is more striking than the
accuracy of the skin in giving notice of changes of temperature,
for a difference of one-third of a degree is detected clearly
when the hand is immersed repeatedly and successively in two
vessels of water, differing only so much in temperature. The
skin detects best very minute changes of temperature when
the medium examined does not fall short of, or exceed very con-
siderably, the usual temperature of the body. Water at 98^
can be much more certainly distinguished by the hand from
water at 100°, than can water at 120° from water at 118.° As
the ears perceive best a difference of tone in sounds, neither too
acute or too bass, or immoderately loud, so the skin judges with
most accuracy of medium temperatures, which produce no very
violent or painful effect on its nerves. Weber is of opinion that
the perception of temperature imparted to each nervous extre-
mity in the skin, goes to unite itself to, and strengthen simulta-
neous impressions in the other ramifications of the same nerve,
thus producing, by the conflux of a great number of impres-
sions, a much stronger result and effect. This, at least, is cer-
tain, that a large conveys much stronger impressions than a small
surface, and estimates changes of temperature with greater deli-
cacy. Thus, if we place the fore-finger of one hand in water
at 104°, and plunge the whole of the other hand into water at
102°, the latter will appear to us to be the warmer. If we plunge
the finger successively into vessels containing hot water, we are
unable to perceive very minute differences of temperature, which
at once become perceptible when we use the whole hand. Nay,
water, which can enei'y be bcrne by a singb finger, will appear
intolerably scalding to the whoW hand. With regard to the

78 Dr Graves on the Sense of Touch.

power the skin possesses (by means of touch and its modifications)
of comparing together two different temperatures or weights,
various and niuhiphed experiments prove that this power is ex-
ercised with the greatest success when the perceptions compared
are not simultaneous but successive. It is the same with the
smell, taste, and hearing; apply to the tongue by means of
camel's hair pencils, small portions of an acid and of a sweet
substance ; if the application of both be in quick succession,
their taste is accurately distinguished and appreciated ; but if they
be applied simultaneously, the result is a less vivid perception
of either, and a blending, as it were, together of the acid and
the sweet. A similar result is obtained by applying the mouth
of phials containing two different, but strongly odoriferous sub-
stances, to the nostrils ; and musicians have long ago remarked,
that when we wish to compare together two notes, it is done
with much more accuracy by striking them in quick succes-
sion, than by striking them simultaneously. Vision appears
to present an exception to the law which governs the other
senses ; for if we want to compare the lengths or the colours
of any two lines, we place them close together, and look at
them at the same moment. As Weber well remarks, how-
ever, the exception is here only apparent, for the truth is, that
we see nothing with perfect accuracy except its image Jails
on the retina at the extremity of the optic axis ; consequently,
on examining two lines close beside each other, although we
think we examine them simultaneously, yet we do not do so ;
our examination and comparison is made by causing the image
of each to occupy the extremity of the optic axis several times in
very rapid succession. The change in the position of the eye
is here so light, and is performed with such ease, that we are
unconscious of it.

Weber made many experiments on the accuracy of the sense
of weight ; of course this sense is more developed in some indi-
viduals than in others, and is capable of being rendered more
exact by practice. Men accustomed to estimate weights by
poising them in their hands, will distinguish perfectly between
two only differing by a thirtieth part. In comparing two
weights, one is poised, and then instantly the other in the same
hand; the intervention of a few seconds between the poising
of the first and of the second, does not prevent their accurate

Dr Graves on the Sense of Touch, 79

comparison. The interval may amount to twenty seconds, and
yet a just estimate will still be made; but when it amounts to
forty seconds, all accuracy is lost. The sight enjoys a still more
accurate power of discrimination than the sense of weight, for a
well practised eye will distinguish between two lines one hun-
dred, and one hundred and ope lines long respectively ; in other
words, will discover a difference amounting to one-hundredth
part of the whole. According to the experiments of Delezen-
nius, quoted by Weber, the sense of hearing is still more accu-
rate, for a well practised musical ear will distinguish between
two sounds differing from each other only jj^, calculating the
number of vibrations the sounding bodies make in a given
time.

A line can be perceived to be longer than another, even when
an interval of fifty or sixty seconds elapses between looking at
the first and at the second, provided that the lines differ j^th
in length. If they differ only ^th, then an interval of thirty-
five seconds may elapse without destroying our judgment ; but
if it be longer, our judgment becomes incorrect. When the
difference between the lines amounts only to g^th, an interval of
three seconds between the examination of each is the longest
that can be allowed without interfering with the correctness of
the comparison. Having followed Weber with some accuracy
through the body of his valuable treatises on the Touch, it may
be worth while to dwell again, for a moment, on some of the
chief conclusions he arrives at. We have a well established and
definite idea of the distance of some parts of our bodies from
others. Thus we feel the distance of the finger points from the
wrist, and we remember that distance. It is the same with the
arms as far as the elbow, and with the foot. These are all
lengths which are firmly imprinted on the mind, and conse-
quently there is a physiological reason for using them, as man-
kind have always done, as standards of measurement. When
any two points on the surface of these parts are touched at the
same time, we can with our eyes shut, and by means of the sense
of touch alone, guess with great accuracy the distance the touched
points are from each other, provided the points are situated
somewhere near the sides or extremities of these parts, as at the
tips or on the sides of the fingers. Here two points will be per-

80 Mr Rose on the Composition of

ceived to be distinct at distances much less than half an inch ;
but if the points be situated elsewhere, as on the back of the
hand, then, although they be distant from each other half an
inch, they will scarcely be felt as distinct, provided the line
joining them is parallel to the long axis of the part ; when it is
transverse, the perception is much clearer, and continues at
much smaller distances.

The discovery, that two equidistant points of contact on the
same surface, excite very different ideas of the distance between
them, according as the space lies lengthways on or across the
limb, is one of the most striking and important which Weber
has made, and can be most readily verified by experiment.

Nor am I aware that modern physiologists have obtained any
results more curious than those relating to the different tactile
acuteness enjoyed by different parts of the skin ; a difference so
great, that the points of a compass applied to the tip of the
tongue, can be felt to be distant, when only distant half a line
from each other ; whereas, to use Weber's own words, " In me-
dio brachio, in medio femore, in dorso scapulae, aliisque in locis
sensusille naturatam parum acutus est, ut apices circini 1^ pol-
licibus Paris, a se invicem distantes, unam impressionem pro-
ferant, si nimirum ita ad has partes admoventur, ut linea utrum-
que apicem inter se conjungens secundum longitudinem brachii
vel femoris posita sit,"

Oil the Composition of the Water of the Lake Elton in Asiatic
Russia, compared with the Water of the Ocean and with that
of the Caspian sea. By Mr H. Rose.*

The Lake Elton, in the Steppe to the east of the Volga, two
hundred miles to the south of Saratof is, on account of its extent,
the most important of the salt lakes in the neighbourhood of the
Caspian Sea. The quantity of the salt of commerce which is
procured from it, is supposed to amount to nearly two-thirds of
the whole quantity consumed in Russia. The lake is of an
elongated form ; the greater diameter stretches from east to
west to the extent of about thirteen miles ; the smaller, from

• Annalen der Physik, 1835.

the Wafer of the Lake Elton, 81

north to south, reaches to about ten. It is so shallow as to be
fordable; and,in truth, it is nothing more than a salt-water marsh
which extends over great beds of salt, which are there constantly
accumulating.

The water, which was analyzed by Professor Rose, was pro-
cured by M. de Humboldt, in his journey of 1829 ; it was pre-
served in a bottle well corked. Some crystals of sulphate of
magnesia having collected in the lower part of the cork, these
were afresh dissolved by heat, previous to the cork being removed;
the water was then poured into a bottle having a glass stopper. '•

At the temperature of 54^ Fahr. the specific gravity of this
water was found to be 1.27288; it did not exert any action on
turnsol paper, and it supplied the following analysis : —

Magnesia, 10.22

Soda, 2.04

Potassa, 0.14

Chlorine, 16.97

Sulphuric Acid, 3.51

When, then, we subtract from the quantity of chlorine thut
found, viz. 16.97, the proportions of it which are combined with
the potassium and sodium, and affix to the remainder, viz. 14.55)
the quantity of chloride of magnesium at 19.75 parts, we obtain
as the analysis of this water —

Chloride of Potassium, . . . 0.23

Chloride of Sodium, .... 3.83

Chloride of Magnesium, . . • 19.7*
Sulphate of Magnesium, . . . 6.32

Water, and a very minute quantity of or-
ganized substance, .... 70.87

100.00

The quantity of matter, therefore, which wholly resists the
action of fire, and which is disengaged from the water, amounts
to 29.13 per cent.

In this water there is no combination of bromine, nor of
iodine, or at least these combinations exist only in the most
minute quantities ; no more are there any carbonates, nor phos-
phates, nor ammonia, nor Hthium, nor metallic substances.
Neither does any gypsum appear, nor any of the other salts of
lime; which is the more surprising, since the brother of the

VOL. XXI. NO. XLI,— JULY 1836. F

82 Mr Rose on the Composition of

author of this article, who accompanied M. de Humboldt in his
journey, found crystals of gypsum in great quantities on the
shores of the lake ; and moreover, the whole of the specimens of
crystalline salts which he procured, contained, on analysis, small
quantities of lime, or a minute quantity of undissolved gypsum.
But the absence of gypsum in this water, proves, without doubt,
that it is insoluble in concentrated solutions of certain salts.

The water of lake Elton, then, is nothing more than a
very concentrated brine, in which enormous masses of common
salt have been deposited during a long space of time, and in
which it still continues to be deposited during the summer
months, because the water which enters it is not sufficient
to replace that which it loses by evaporation. For little as
the temperature of the water of this lake falls, great quan-
tities of the crystals of sulphate of magnesia are found in
it. Moreover, both its composition and its specific gravity must
undergo great variations with the temperature. Accordingly,
the banks of the lake in summer present only crystals of gypsum
and of common salt ; but in winter there are besides many crys-
tals of sulphate of magnesia which are again dissolved in sum-
mer, so that pure common salt may be procured from the lake.
The composition of this water is precisely what we should
obtain by evaporating a very large quantity of common sea
water at a very moderate temperature, so long as it deposited
common salt.

The water of the other salt lakes, to the north-east and east
of the Caspian, is somewhat similar to that of lake Elton, but
has not exactly the same composition. That of lake Bogda
is, according to Mr Erdman, altogether more like sea water.
But of all the salt waters which have been analyzed, that of
lake Elton most resembles the water of the Dead Sea. This
latter has an inferior specific gravity, and also contains a smaller
proportion of solid matter. According to the analysis of Gay-
Lussac, undoubtedly of all others the most accurate, its specific
gravity is 1.2283, at 63° Fahr. ; and it contains 26.24 per cent of
solid matter, which consists of metallic chlorides, viz., those of so-
dium, calcium, magnesium, and potassium, with some traces of
gypsum. The absence of the sulphate of magnesia, and the
presence of chloride of calcium, distinguish it from the water of
lake Elton.

the Water of the Lake Elton. 83

Next to those already named, the water of lake Ourtnia
near to Tauris in Persia, appears to be that, of those hitherto
analyzed, which contains most salt. According to Dr Marcet
its specific gravity is 1.16507, and it contains 22.3 per cent of
solid matter, which consists of common salt, sulphate of mag-
nesia, and sulphate of soda.

The similarity between the composition of these waters and that
of the ocean and of salt pits is striking. The salts which are
found in the waters of the ocean, according to known analyses^
do not differ from those of which Mr Rose has demonstrated the
existence in the water of Elton, except that it is generally ad-
mitted, after the principles laid down by Murray, that there is
in sea water the simultaneous presence of sulphate of soda, and
the chlorides of magnesium and calcium ; although in all pro-
bability these salts, in extensive solutions, would mutually de-
compose each other. We cannot, it is true, determine with cer-
tainty in what manner the constituent parts of two salts are
combined when these salts are of different solution or insoluble ;
but if it be admitted that the salts in the saline solutions are in
the state of simple and not double salts, there is the greatest
probability that in most cases the salts exist simultaneously in
the solution, so that they separate by crystallization, by means
of evaporation, at the ordinary temperature, or when it is some-
what elevated. That salt which is the least soluble is first sepa-
rated. The propositions which Murray adduced in the main-
tenance of his hypothesis are not tenable. It cannot b« denied
that the sulphate of lime sometimes can maintain itself dissolvoi
more easily in saline solutions than in an equal quantity of
water; but usually it requires more time for its precipitation.
In summer evaporation gradually effects the deposition from
salt waters, first of gypsum, then of common salt ; then of sul-
phate of magnesia, more or less pure, and sometimes mixed with
common salt ; and the chlorite of magnesia, or the most soluble
of salts, remains in the sea water. Evaporation never produces
sulphate of soda. The brother of the author of tliis article
never found any trace of it on the banks of lake Eltou ; and in
its waters are only found crystals of the sulphate of magnesia.

It is true that at different temperatures the combinations
partly change in saline solutions in a singular maBQer, but still
F 2 *

84 Mr Rose on the Composition of

almost always from the sole cause that the salts are not then
equally soluble. A mixture of common salt and sulphate of
magnesia exhibits in this view the most extraordinary anomalies.
If both be dissolved in a sufficient quantity of water, and if
then, at the ordinary temperature, at least in summer, the water
of solution be evaporated, the sulphate of magnesia and common
salt are deposited. If the solution contain a large proportion of
the latter and but little of the former, a part of the common salt
is first deposited, then the other, while common salt still remains
in solution ; because in the heat of summer the sulphate of
magnesia is to a very shght degree more difficult of solution than
common salt. If the temperature descends to the freezing point,
or ascends beyond 122° of Fahr., in both cases sulphate of soda
is deposited, and it is formed from chloride of magnesia, because at
the freezing point the sulphate of soda is, of the four salts which
can be contained in the solution, viz. common salt, sulphate of
magnesia, sulphate of soda, and chloride of magnesia, the most
difficult to dissolve, and because at about 122° Fahr. it sepa-
rates itself as an anhydrous salt. There is, therefore, ground
for supposing that at the ordinary temperature the sulphate of
magnesia and common salt simultaneously exist.

It was from these considerations that Mr Rose was induced
in his indication of the constituent parts of the water of Lake
Elton, to admit the combination with the magnesia of the whole
quantity of the sulphuric acid which he had found, although
this was in opposition to the opinion of Murray, which had also
been adopted by Dr Marcet. And if some chemists in the
analysis of sea-water by the manner of evaporation, and by
treatment with alcohol, have discovered sulphate of soda, this is
incontestably owing to the circumstance, that, in effecting the
evaporation, they had employed a heat reaching almost to that
of ebullition. Those who conduct the evaporation of this water
at a temperature below 122°, cannot obtain any sulphate of
soda.

As to the specific gravity of sea water, and the proportion of
solid matter it contains, they both appear to be very variable.
M. de Humboldt is the first who has attracted attention to
these points ; and he reckons that the proportion of soli^ parts
-varies from 3,^2 to 3,87 per cent. Of recent researches, those

the Water of the Lake Elton, 85

of Mr Lenz, which have been made with the greatest care, and
with due regard to those going before, fix the maximum of the
specific gravity of the water of the Atlantic at 1,02856, and of
the Southern Ocean at 1,028084.

From his numerous observations, Mr Lenz concludes that
the waters of the Atlantic contain a greater proportion of salt
than those of the Southern Ocean. The Indian Ocean, as the
connecting medium of these two great masses of water, is conse-
quently somewhat more salt on the side of the Atlantic than on
the confines of the Southern Ocean ; that is to say, on the west
than on the east, whilst, at the same time, this difference is not
considerable. One circumstance on this point is exceedingly
curious, viz., the statement of Wollaston, that the water of the
Mediterranean, fifty English miles to the east of the Straits of
Gibraltar, at the depth of 670 fathoms gives, when heated to
302° of Fahr., a proportion of salt which amounts to 17,3 per
cent., and a specific gravity of 1,1288; whilst more to the
east, at two places a little removed, it possessed only the usual
proportion of the waters of the ocean.

It is well known that enclosed seas have often a much smaller
proportion of salt than others. This is especially notable in re-
lation to the Baltic, in which this proportion diminishes as the
distance of its communication with the German ocean increases.
It even appears, according to the observations ofWilkie in 1771,
that in the Sound, near to Landskrone, the west wind, and more
especially the north-west, decidedly increases the specific gravity
of its waters, whilst the east wind correspondingly diminishes it
The Caspian exhibits a similar phenomenon, but in a different
direction. Here the water almost entirely loses its proportion
of salt in the situation where the enormous watery mass of the
Volga enters, and it is only after a continuance of southerly
wind that the water becomes salt even at Astracan.

Mr Rose has analyzed some water which was given him by
his brother, and which was taken from this sea in N. Lat. 45° 39,
at the distance of 56 miles from the last of the islands which
form the embouchure of the Volga, at a place where it was only
three and a half fathoms deep. This water was so fresh
that it could be drank like spring water. The analysis, although
mperfect on account of the small quantity which was subjected

66 Mr Rose on the Composition of

to experiment, sufficed nevertheless to shew to how small a pro-
portion the entrance of the Volga reduces the salt in the water
at the northern part of this sea. The specific gravity, at 54° 5'
Fahr., was only 1,0013, and one hundred parts of water gave,

Chlorine, . . 0,0455

Sulphuric Acid, . 0,0258

Lime, . . 0,0176

Soda, . . 0^0418

Magnesia, .. 0,0160

0,0455 of chlorine, combined with 0,0299 of sodium, the re-
maining 0,0016 of soda with 0,00205 of sulphuric acid ; 0,02375
of sulphuric acid was then combined in the water in the form of
gypsum, with 0,0169 of lime, so that 0,0007 of hme + 0,016
magnesia, were dissolved as bicarbonates. In 100 parts, then,
of water, are dissolved—
Chloride of Sodium,

Sulphate of Soda,

Sulphate of Lime,

Bicarbonate of Lime,

Bicarbonate of Magnesia,

Water, with a very small quantity of organized matter,

0,0754
0,0036
0,0406
0,0018
0,0440
99,8346

100,0000

The salts obtained by evaporation in a bottle of water, ob-
tained near Astracan by the brother of Mr Rose, contained a
much less proportion of sulphuric acid, as well as of lime and
magnesia, the reason of which was, that during the evaporation,
the earthy carbonates, as well as a great part of the gypsum,
were precipitated, and could not easily be removed from the ves-
sel. On the first action of the heat, the salt became black, and
sank to the'^bottom ; and 0,670 of a scruple, heated to a high
temperature, afforded to Mr Rose 0,1275 of a scruple of sul-
phuric acid, 0,2593 of chlorine, 0,0549 of lime, 0,2320 of soda,
and 0,0500 of magnesia. These parts formed, in the salt in the
state of fusion, the following combination : —

Chloride of Sodium,

0,4293

Sulphate of Soda,

0,0080

Sulphate of Lime,

0,1322

Sulphate of Magnesia, .

0,0692

Magnesia, . • •

0,0266

0,6652

the Water of the Lake Elton, 87

Mr Rose remarks, that this analysis seems to indicate that a
part of the magnesia perhaps exists in the water of the Caspian
Sea in the state of sulphate of magnesia ; but, in my analysis, I
have admitted the combination of the magnesLi with the carbonic
acid, and that of the lime with the sulphuric acid, because it is
impossible to determine, by the conclusions derived from analy-
sis, what proportion of the two earths is combined with each of
these two acids.

The water of that part of the Caspian which is nearest the
mouth of the Volga is then comparatively free from solid con-
tents. The excess of the specific gravity of the water of the
Baltic, even where it is least salt, over that of pure water, is five
times, and between the islands Laland and Femern more than
seven times as great as the corresponding excess of the water
which was analyzed from the Caspian Sea.

Eichwald also, in the account of his voyage on the Caspian,
informs us, that the water, at the distance of four miles from the
island formerly alluded to, was still so slightly brackish, that the
vessel in which he sailed could there fill its water-casks. Accord-
ing to him, it is only in a lower latitude than 45°8' N., where the
water of this sea becomes deeper, that it becomes salt by degrees,
and begins to assume the green colour peculiar to sea water ; and,
at the mouths of the great rivers, such as Terek and Ssoulak, it
is found soiled, muddy, and scarcely salt.

The Caspian, not only to the north and north-east, but round
all its banks, is surrounded with salt lakes. The water which
these contain is so concentrated, that, as in lake Elton, the salt is
deposited, simply by evaporation, in thick beds, which are easily
broken up with iron bars. These lakes are very numerous upon
the western side, especially upon the peninsula of Abscheron,
near Bakou, where, according to Eichwald, they give out an
odour like that of violets, and also upon the eastern side, espe-
cially round the Gulf of Balchau, upon the peninsula of Dardcha^
and on the island of Tchelekan.

t« ( 88 )

Farther Illustrations of the Propagation of Scottish Zoophytes,
By John Graham Dalyell, Esq.* Communicated by
the Author.

Oveepassing for the present those nicer distinctions pro-
posed by the arrangement and nomenclature of modern sys-
tems, I mean by Zoophytes to signify in general such animated
products as resemble the form of plants, and consist wholly or
partially of beings analogous to the hydra or polypus. 'No
other name can be equally expressive of their nature.

Most of the lower animals propagate through the medium
of an ovum, invested by an integument of different tenacity
or induration, containing the elements of their progeny along
with nutritious matter. This ovum is in itself inert, devoid of
spontaneous motion, nor is it susceptible of being displaced by
the struggles of the foetus included, as may be seen during the
internal revolution of certain planariae and the vehement ac-
tion of various sepiae.

The development and escape of the foetus from the ovum
may sometimes ensue within the parent, as well as after extru-
sion of the ovum from its body.

Though necessary to premise these general principles, they
are disturbed by many anomalies ; whence the naturalist is
compelled to resort to desultory illustrations in establishing
analogies between certain animals now standing far apart in
the Systema Natura:,

I. A healthy and prolific Actinia commonly affixes itself to
the side of its vessel horizontally, that full scope may be al-
lowed to its organs. Then the distended tentacula of the
lower half are occupied by the young in various stages ; and
interspersed among them, or separately, in other tentacula may
be seen an opaque corpusculum of infinitely smaller dimensions,
pursuing an irregular course through the liquid contents.

On amputation of the tentacula, one or more of these latter
beings is discharged. All are opaque, red, solid, and of consider-
able specific gravity, and having a general resemblance to some

• The previous observations are contained in the Philosophical Journal for
October 1834, and in the Report of the Proceedings of the British Association
»t Edinburgh.

Mr Daly ell on the Propagation of Scottish Zoophytes, 89

of the anivialcula infusoria. But under the microscope they
prove of diversified form, many resembling flattened pease,
some elongated or exhibiting irregular prominences, some al.
most spherical, others as if composed of two or even of three
unequal spheres, and some which cannot be referred to any fa-
miliar figure. Short cilia or stout hairs environ their circum-
ference, whatever be its outline, evidently instrumental, though
not exclusively so, in their motion. This is also much diver-
sified, being either progressive in a regular or irregular course,
by describing an orbit ; or when the body seems compounded
of spheres, by horizontal revolution, as on an axis, at the point
of union.

If extracted artificially, the corpuscula perish within a few
days. But as the actinia is viviparous, discharging its young,
having attained maturity, by the mouth, either in the course
of nature or while disgorging the residue of its food,— so do
the corpuscula sometimes, though very rarely, accompany
them.

In this manner fourteen animated beings were produced at
once by an actinia equina or mesembrt/anthemum, previously the
parent of large and perfect progeny, seven or eight months in
my possession. Six were the young with tentacula, and eight the
corpuscula just referred to ; which latter being separated and
set apart in different vessels, could be identified with those ex-
tracted from the tentacula. All were sufficiently vivacious,
sometimes moving, sometimes reposing ; their excursions were
longer or shorter, quicker or slower, regular or irregular, va-
rying in space and duration, but always somewhat laboured,
as if to overcome their own specific gravity, exceeding that of
the surrounding medium.

Activity subsisted among the whole during eight days, when
their shape had undergone some alteration. One in particular
had become truncated in front ; convex, clearer, and inflated
behind, and exactly resembling the upper section of an ordi-
nary sugar-loaf. Next, their motion relaxed. Though still mere
specks of animated matter, inequalities might be recognised at
one end, while the other was smooth and convex ; and the sides
had attained greater transparency. The cilia disappeared, and
they became stationary. In eleven days from their origin, in-

90 ' Mr Dalyell on the Propagation of Scottish Zoophytes.

cipient tentacula were indicated in one, and in nineteen days
eight or nine could be enumerated in another, which, now ma-
tured from its ciliated animalcular form, had affixed itself as
a young actinia by the base. Others also adhered, and were
actjuiring a cylindrical shap«, but their tentacula were of later
evolution.

Thus, at an early stage, the actinia appears under a peculiar
form, altogether different from its perfect shape ; it is endowed
with vigorous action, and provided with certain external organs,
which are obliterated as it becomes stationary, and as others are
unfolded.

II. Having passed per saltum to the Alcyoniiim^ we find it
consist of a compact gelatinous or fleshy matter, studded with in-
numerable cells sunk in its substance, which are inhabited by
vivacious hydrae. Diff^erent species or varieties occur in the
Scottish Seas, especially the gelatinosum, and a thin, green, flat-
tened palmate kind, which has perhaps escaped the notice of na-
turalists hitherto.

A white, opaque, ovoidal, or nearly circular, flattened cor-
pusculum, previously invisible, issues from the fleshy part of
these products, whence it seems to be elicited, particularly by
the influence of the light. On removal of a small specimen, that
had already afforded many, from a dark situation to a moderate
degree of light, at least 150 quitted their recesses within an
hour. These beings are endowed with much greater activity
than the corpuscula of the actinia ; their courses are alike di-
versified : they swim through the water in all directions, regu-
larly and irregularly ; ascending to the surface, or descending to
the bottom : pursuing a straight line, describing an orbit, or
tumbling about among the neighbouring substances. Meanwhile,
as if of soft consistence, their form alters, and the action of the
cilia environing the body, is alternately accelerated and relaxed.
At length, having become stationary, a margin diffuses around
the body, and supervening transparence of the centre soon ex-
poses an immature hydra within, which in nine or eleven days
is displayed perfect from its cell. The inner surface of each
tentaculum is now clothed by a double row of stout dark cilia in
rapid motion, but in opposite directions, for as those of one side

Mr Daly ell on the Propagation of Scottish Zoophytts, 91

strike upwards, those of the other strike downwards. Farther
diffusion of the basis adhering below forms additional compart-
ments for other hydra.

The propagation of the Flustra carhasea^ foUacea, and trun-
cata, ensues after a similar fashion. A ciliated corpusculum,
spherical, ovoidal or irregular, quits the leaf, pursues its courses
in the water, becomes stationary, adheres, and a nascent flustra
arises from the spot. Above ten thousand such corpuscula have
been produced by a moderate sized specimen of the flustra,^
liacea, tinging the bottom of a vessel yellow from their multi-
tude, and vitiating the water by their decay.

III. Many of the Sertularia? propagate through the medium
of a minute, flattened, smooth being, with a regular gliding
motion, originating in the vesicles, which I have provisionally
denominated plamda, from its resemblance to the genus Pla-
naria.

But a remarkable peculiarity occurs in the Sertularia dkhoto^
ma, or Sea thread, one of the most elegant and delicate of the
tribe; where 1500 or 2000 living hydrae sometimes adorn a
single specimen. Its vesicles are rarely found ; when present they
are in the proportion of about one to thirty hydrae, difi*ering in
nothing externally from the general aspect of others ; replenished
also by twenty or thirty greyish corpuscula, with a dark central
nucleus. At first, all are immature and quiescent, but motion at
length commences : the corpuscula become more distinct ; seve-
ral slender arms protrude from the orifice of the vesicle, which
are seen in vehement action, and, after many struggles, an ani-
mated being escapes. But this has no relation either to the
planula of the Sertularia?, or the corpusculum of the flustra,
alcyoniuni, or actinia. It might be rather associated with the
Medusariae. Before ascertaining its origin, I had named it Animal^
culum tintinnabulum, from its general resemblance to a common
hand-bell, for the purpose of recognition. This creature is
whitish, tending to transparency, about half a line in diameter;
the body is like a deep watch-glass, surmounted by a crest rising
from the centre, and fringed by about twenty-three tentacula
pendent from the lip below. These are of muricate structure, or
rough, and connected to the lip by a bulb twice their own dia-
meter. The summit of the crest unfolds occasionally into four

92 Mr Dalyell on the Propagation of Scottish Zoophytes.

leaves, and four organs prominent on the convexity of the body
appear at its base. When free the animal swims by jerks, or
leaps through the water, or drops gently downwards; it is in-
vited to move by the light, and it has survived at least eight
days. Then it disappears, at least I have not been able to pur-
sue its history longer. No other product has ever issued from
the vesicles of the Sertularia dichotoma Fig. 1. enlarged.

IV. The only mode of propagation definitely ascertained of the
Hydra tuba, the largest of the Scottish hydrae proper, is by the
gemmation of the young from the body of the parent, and this is
gemmation in the correct acceptation of the word. I kept a co-
lony of these animals and their descendants during six years :
numbers attained maturity ; they fed rapaciously, grew and bred,
succeeding at all seasons of the year. But, in February
and March, the face or disk of some hydrae is invested by a pen-
dulous flexible prolongation of an inverted conical form, obliterat-
ing the tentacula entirely. The apex being connected with the
disk, this pendulous mass extends two or three lines in the course
of time, and is gradually developed in twenty or thirty succes-
sive strata gradually broadening outwards. When more ma-
ture, the vehement clasping of extending arms at the extremity
denotes, that each stratum is an animated being, which, after
excessive struggling, is liberated, to swim at large in the water.
This, also, may be associated with the Medusariae. It is consi-
derably larger than the preceding, two lines in diameter ; of a
whitish colour tending to transparence. The body resembles a
flattened watch-glass ; the margin dilating into from five to twelve
horizontal broad flattened lobes ; each cleft half-way down the
middle, and with a black glandular looking speck in the centre of
the fork. A crest resembling a quadrangular-clustered column
rises from the convex surface of the body, and four organs may be
sometimes observed on the same surface near its base. Motion is
accomplished in jerks or leaps, somewhat as by the Medusas pro-
per, from percussion of the lobes on the water, the crest being
downwards. Whether the pendulous mass or its individual parts
be contained in one common involucrum, or in many specific inte-
guments, is uncertain, but each of the animals composing it
comes successively to maturity and departs, As the pendulous

Mr Daly ell on the Propagation of Scottish Zoophytes, 93

prominence disappears, the vigour of the hydra is restored, and
the tentacula, liberated of the incumbrance effecting temporary
obliteration, resume their natural form and functions. Weeks
elapse in the course of this process, and during survivance of
the animals. Fig. 2, 3. enlarged.

V. In addition to previous observations the Tubularia indi*
visa, I shall merely remark that here and in the Tubularia poly*
ceps, a compound uterus of many cysts or sacs is generated on
the face of the hydra. Each contains the elements of the pro-
geny, expelled in a white, solid, spherical or ovoidal form, whence
the external organs are speedily unfolded. But if accidentally
retained, evolution succeeds within the cyst, and the tentacula
are seen protruding from its orifice previous to expulsion.
Probably, therefore, the progeny is expelled as a foetus, invest-
ed by an amnios preserving its solid spherical or ellipsoidal
form. Borne on the originating tentacula, it enjoys the facul-
ty of transition, until reversed and rooted, which succeeds
sometimes within two days of expulsion.

VI. The various species of Scottish Cristatellae propagate
under greater analogy to the higher animals, by an ovum with
a harder shell and fluid contents. This, after escaping by de-
cay of the Cristatella mirabilis, has required 200 or S30 days
to mature the young, and 167 days for that of the Cristatella
lacustris, when the ovum splits asunder horizontally to allow its
exit.

The adult sertularia and the flustra enlarge by gemmation in
its proper sense. Buds are generated at the extremities : each
contains a hydra, which bursts the integument investing it,
and protrudes from the cell to display its organs. Likewise
new cells, formed by the enlarging leaf of the flustra, contain
originating hydrse, which, reaching maturity, display their
parts.

But from the preceding observations it appears exceedingly
doubtful whether the name of ovum or gemmule can be ap-
propriately applied either to the ciliated coi'pusculuvi or
plannla as some learned naturalists propose ; perhaps each
should be considered rather as an animal advanced a stage

94 Mr Daly ell on the Propagation of Scottish Zoophytes,

beyond that of the gemmule or oxmni^ and possibly bearing
nearly the same relation to it as the larva or caterpillar bears
to the ovum of insects. Neither can I at present view the va-
rious, protracted, interrupted, alternate motion and quiescence
of these beings, otherwise than as resulting from animation ;
thence necessarily ascribing to them such characteristics as are
inconsistent with the technical description and nature of an
ovum. They repose permanently, also, on advancing still
another stage, as the larva on entering its second state, which,
though less conspicuous, does ensue with the actinia, and is
amply demonstrated by the sertulariae, flustrae, and alcyonia ;
and this repose terminating in apparent decay, is preparatory
to the existence of that original hydra, which founds the spe-
cimen generating a thousand others from its basis.

Favourable conditions may enable more successful natural-
ists to prosecute the history of the two beings allied to the me-
dusae, and to ascertain whether any analogy subsists between
the propagation from the sac on the face of the hydra of the
Tubularia indivisa, and the propagation from the pendulous
nidus on the face of the Hydra tuba.

Some of the animalcula infiisoria may be probably found
the progeny of zoophytes in an intermediate stage.

flf Fig. 1. Animal from the vesicle of the Sertularia dichotoma ; crest a ; tenta-
cula, b. enlarged.

^. Fig. 2. Animal from the disc of the Hydra tuba ascending; crest «; arms b"
Fig. 3. The same quiescent — both figures enlarged.

( 95 )

Letter from M. Theodore Virlet to M. Arago, on the Phench
meiion of Dolomisation^ and the Transformation of Rocks in
general.

I HAVE just read in a journal an account of the discussion
which took place at the meeting of the Academy of Sciences, on
the 12th October, regarding M. de Buch's theory of dolomisation
—a theory which must be allowed to be bold and ingenious, if
reference be made to the period in which it has been advanced.
It is known that I am far from acquiescing in all the opinions of
this celebrated geologist ; but as I did not hesitate, at a time
when comparatively unacquainted with the science, to combat
such of his opinions as I could not admit, I now think it due to
the well known independence of my character, to support a fact
advanced by him, which has been disputed, and which, besides,
has direct reference to a question which has occupied much of
my attention, viz. the transformation of rocks in general. This
is one of the newest and most important questions of geology,
and it ought to afford us the means of making rapid progress in
the study of the composition of rocks, and lead to the solution
of a multitude of facts hitherto regarded as inexplicable.

Some years ago, in describing to the Geological Society of
France, the modifications occurring in a bed of hematitic iron,
which I had an opportunity of observing near Sargans, in the
Canton of St Gall, Switzerland, I was led, by the recollection of
numerous analogical facts falling under my own observation,
and what I have mentioned in my account of the Geology of
Greece, to consider the phenomena of the transformation of rocks
under two different points of view, and to divide the modified
rocks into two very distinct classes.

1. Such as have been modified, whether by the prolonged
action of heat, or by that of electrochemical agents, or by both
of these causes united, which have changed the combinations or
primitive arrangement of the molecules in relation to each other.

2. Rocks which have been modified by chemical actions and
reactions, with the assistance of foreign- agents (such as the gases),
which have acted directly upon them, and changed their primi-
tive nature. It is in this class that dolomite ought naturally to
be arranged.

96 M. Virlet on the Transformatum of Rocks.

The first manner of regarding the modification of rocks, which
I was the first to propose, allows me to explain how certain beds
placed in the midst of other beds, may be more modified than
the latter, or may even undergo a complete modification, without
the others, whether they were in contact, or even formed the
lower part of the same deposit, experiencing any sensible change
in their original state, and that without any of the beds being
confounded with each other. The opinion which I advance on
this subject, results as much from my own observations as from
the manner in which I regard the first sandy deposits as being
formed at the period when the waters began to condense on the
surface of the earth ; and although many may regard it as some«
what heretical, I have no doubt that it will soon be admitted by
all accurate observers, viz. That all stratified rocks, without ex--
cepting gnelsSt the mica-slates, or clay-slates, S^c. have been
originally rocks of sediment, Jbrmed by mechanical aggre-
gatkyfi, and that they have acquired the crystalline characters
which noio distinguish them, by a series of modifications which
ihey have undergone posteriorly to their being deposited.

It is conceived, on the contrary, according to the second kind
of modification of rocks, that, in the greater number of cases, all
the beds are confounded in such a manner as to present a single
mass without distinct stratification ; such, for example, as dolo-
mite, certain deposits of sandstone and clay transformed into
jaspers or trachytic porphyries, and other rocks which I have
often had occasion to enumerate ; for the chemical agents, by
penetrating across a certain number of beds, or even the entire
mass, have separated a part of the elements of the original
rocks and substituted others, or else have formed new combina-
tions, and finally united the whole mass of the deposit. It is to
these considerations that I wish chiefly to direct attention, as
they have reference to the phenomena of dolomisation.

I do not dispute, I even admit, that there are dolomites which
should be called primitive, whatever may be their geological age ;
that is to say, which were the result of a series of simultaneous
deposits of carbonate of lime and of magnesia, for magnesia was
at least as abundant in nature as lime, particularly at the time
when the old deposits were formed. ^l[ie?>Q primitive dolomites,
however, always present a distinctive character in being regularly

M. Virlet on the Transformation of Rocks, 97

stratified, like the other rocks to which they may be found sub-
ordinate ; while the dolomites of which I now speak, and which
I shall call dolomites of transmiitatiofi (such as are described by
M. de Buch as occurring among the Alps, and many others which
I could mention), are without stratification, presenting irregular
masses, combined with other characters which individuals accus-
tomed to observe modified rocks can seldom mistake. No one
who has visited the dolomites of the Alps can entertain any
doubt of the reality of the phenomenon of dolomisation, however
difficult the explanation of it may at first appear, since chemistry
teaches us that carbonate of magnesia is not volatile, or that it is
decomposed at a red heat, an objection which has been urged by
M. Thenard. It was in fact these considerations that caused me
to be among the first to publish my doubts on the subject, at a
time when no one undertook to ascertain, by chemical analysis,
that the parts of the deposit which had not been modified, were
not equally magnesian ; that is, did not form beds of primitive
dolomite — a circumstance which would have reduced the pheno-
menon of the change of limestones into dolomite, to a simple
phenomenon of modified crystallization, analogous to that, for
example, which has determined the change of the compact Jura
limestone of Carrara, and that of the compact chalks of some
parts of the Pyrenees, into granular limestones or statuary mar-
ble. One of my friends, M. Des-Genevez, who possessed a very
extensive knowledge of chemistry, and whose early scientific
works afford so much reason to lament his premature death, has
unhnppily been lost to the sciences before publishing the results
of his chemical researches on dolomisation. These, he has many
times assured me, had demonstrated to him that there existed
an insensible passage from beds of unaltered carbonate of lime to
dolomite or double carbonate of lime and magnesia. Thus the
transformation of certain calcareous rocks into dolomite, poste-
riorly to their formation, appears to me to be a well established
phenomenon, and requires, in my opinion, only to be properly
explained in order to be admitted by all.

Who does not know how many facts, perhaps among the most
difficult to comprehend previously,havealready been explained by
the excellent researchesofM. Becquerel in electrical chemistry, and
the important labours of M. Fournet, regarding the formation of

VOL. XXr. NO. XLI. — JULY 1836.

$8 M. Virlet on the Transformation of Rocks.

veins ? Numerous other facts, although not yet fully explained,
have been brought forward and admitted without dispute. For
example, I have proved that the emery of Naxos comes from
veins, and consequently had been formed, like the greater num-
ber of specular iron ores, by means of volatilization and sublima-
tion ; yet the corundum and oxide of iron, the mixture of which
constitutes emery, are not more volatile than the carbonate of
magnesia, which forms the subject of dispute.

Since our chemical knowledge, then, does not always enable
us to explain the phenomena whose existence we can prove, does
it follow that we ought to call them in question ? Has nature
no mode of acting which surpasses our knowledge ? And could
she not proceed, for instance, by means of double chemical de-
composition ? On this supposition, the phenomenon will admit
of easy explanation. It is well known that all the muriates are
volatile, or at least susceptible of sublimation. Magnesia might
then easily reach the state of a muriate, and occasion the for-
mation of a soluble hydrochlorate of lime, which would be car-
ried off by the infiltration of water ; while the magnesia, on the
contrary, would be combined with that portion of the carbonic
acid set at liberty, and would thus serve to form the double car-
bonate of magnesia and of lime, which constitutes dolomite, pro-
perly so called. In this there is certainly nothing inadmissible
or contrary to reason, inasmuch as the hydrochloric acid gas is
one of the gases most frequently disengaged from volcanos, and
the muriates ought to have been disengaged more abundantly
in former times, if we admit, with geologists of the modern
school, that the immense deposits of rock-salt which exist in
saliferous formations, are deposited by volatilization, in the midst
of the strata which they penetrate.

I am, therefore, of opinion that the modifications of rocks of
the second class may henceforth be all explained by means of
double decomposition — a process which has enabled one of my
friends, M. Aime, to produce in the laboratory crystallized specular
iron ore, analogous to that of the Island of Elba, as well as pure
iron equally well crystallized — a substance hitherto unknown to
mineralogists ; whence I conclude that the time is not perhaps
far distant when we shall be able to produce with ease all the
species of precious stones, without even excepting the diamond.

( 99 )

An Jccount of some Experiments and Observations on the Parr,
and on the Ova of the Salmon, proving the Parr to he the young
of the Salmon. By Mr John Shaw. Communicated by the
Author.

That the facts which I am about to communicate regard-
ing the Natural History of the Parr may appear not altoge-
ther undeserving of consideration, I may be allowed to observe,
that my remarks have not proceeded from a hasty or imperfect
observation, but from the experience of many years sedulously
devoted to the study of the subject. The whole of my life,
with the exception of a few years, has been spent on the banks
of the streams where the salmon has been in the habit of de-
positing its spawn, and where, of course, the parr likewise
abounded ; my facilities of observation have, therefore, been
as ample, as my efforts to discover the true history of this fish
have been unremitting and laborious.

In opposition to the opinion held by most writers on the
subject, I have always believed that the parr was the produce
of the salmon, and that all attempts hitherto made to trace the
early history of the latter fish have been unsatisfactory and
fanciful.

To enable me to watch the progressive growth of the parr,
I caught, on the 11th July 1833, seven parrs, and put them
in a pond supplied with a stream of wholesome water. In this
pond they continued to thrive remarkably well, taking flies,
and sporting on the surface in fine weather in perfect health.

In the April following (1834) they began to assume a dif-
ferent appearance from what they had when first put into the
pond, which was evident enough, even while they continued swim-
ming at large in the water ; but wishing to examine them more
particularly, and at the same time to convince my friends of
the fact of their having changed their appearance, I caught
them with the cast-net on the 17th May 1834, and satisfied
every individual present that they had assumed the perfect ap-
pearance of what is called the salmon-fry. They were now
of a beautiful blue on the back, with a delicate silvery ap-
pearance on the sides, and at the same time the silvery scales

100 Mr Shaw's Eocpeiiments and Observations on the Parr,

came readily off on the hand when touched ; the belly was
white, and the average length was six inches, vertebrae sixty.
There is one circumstance which occurred during the course
of my experiments on these fishes which may be worth men-
tioning here, although I do not mean to attach much import-
ance to the fact. About the first week in May, after they
had undergone the change which I have mentioned, I was
surprised to find that they were decreasing in number, and,
on examination, I found that they had leaped out of the pond
altogether, and were lying dead at a short distance from its
edge. Whether this circumstance arose from their eager pur-
suit after the flies and other insects sporting on the margin, or
whether they had leaped out of the pond in hope of making their
escape to the sea, (it now being the period of their migration,) I
shall not venture to offer an opinion. In March 1855, 1 again
took twelve parrs from the river, w hich were distinctly marked
with the characteristic bars of that fish. The average length of
these individuals was about six inches. These also I put into
a pond prepared for such experiments, supplied with a stream
of pure water, and, according to my expectation, they had, by
the end of April ^ 835, assumed the perfect appearance of the
salmon-fry, — the bars being overlayed by the new silvery
scales which the parrs of two years old invariably put on, pre-
vious to their departure for the sea.

From these experiments I think there can be no room to
doubt, that the large parrs found in the river in autumn and the
succeeding spring, (that is, at a period before the salmon-fry
migrate,) are in reality the salmon-fry themselves, and that the
small or summer parrs, (called by Dumfriesshire anglers the May
parrs,) which still remain in the river, are those of one year old,
and that they must remain another year, before they depart in
the character of salmon-fry. The fact of the parr changing its
appearance at a particular season, previous to its migration to
the sea, is a circumstance which must be known to many who
have made similar experiments, as well as to every angler of
any observation, who has angled in rivers w^here this fish
abounds, as there are many taken in April, before they have
completely assumed their silvery coat, thus demonstrating the
fact of themselves. The salmon fry has hitherto been errone-
ously supposed to grow to the size of six or eight inches in as

and on the Ova of the Salmon. 101

many weeks, and to take its departure for the sea after this
brief period has elapsed. The rapidity with which the parr of
two years old assumes the appearance of the salmon-fry, has
led to this error, — the parr taking about the same time to per-
fect its new dress, as the young salmon is supposed to take in
attaining the growth at which it has arrived at the period of
its migration.

As the continuance of the parr in the river for two years, as
well as the fact that there are always two generations in the
river at one time, is not generally believed, it may be necessary
to detail the evidence by which the truth is established.

That this fish should not be found in the river in an earlier
stage than the May or summer parr, had long appeared to me
a very extraordinary and perplexing circumstance. I there-
fore made a very minute examination of the stream, where the
old salmon had spawned the previous winter, and I found a
very small but active fish in vast numbers, which I concluded
must be the young parr, or samlet of that season. In order to
prove the fact, I provided myself with a hoop, on which I
stitched a piece of gauze, (the fishes being too small to be
taken with any thing of a larger mesh,) and on the 10th
of May 1834 I caught two or three dozen of them. They
measured about 1 inch in length ; their heads were large
in proportion to their body, which tapered off towards the tail
in form of a wedge, or small pin ; and the small transverse
bars peculiar to the parr were very distinctly marked. I then
put them into two different ponds provided with a proper sup-
ply of running water, where they appeared to thrive remark-
ably well. In the succeeding May (1835), that is, after they
had been in my possession twelve months, I again took a few
of them from the pond, for the purpose of seeing what pro-
gress they had made. I found that they had increased in that
time to the length of S}^ inches, on an average, and that they
corresponded in every respect with the parr of the same age to
be found in the river, but that they did not as yet indicate in
the least degree the appearance of the perfect fry. Being con-
vinced, nevertheless, -from the result of my former experiments
on the parr, that they would ultimately assume a different ap-
pearance, I retained them in the pond, and in the second week
of May 1836 they had assumed (as in the former experiments)

102 Mr Shaw's Experiments and Observations on the Parr,

precisely the same appearance as the salmon-fry. They measure
about 6^ inches in length, of a beautiful blue colour on the
back ; the sides bright and silvery ; the dorsal and pectoral
fins and tail tipt with black ; the belly, ventral, and anal fins
white ; and on the most minute comparison with those at the
time descending the river, not the slightest difference could be
perceived, which proves what I have above stated, that the
parr remains in the river two years before it assume the silvery
appearance of the young salmon or smolt.

This active little fish, which has, as I have shewn, turned out
to be the parr of a few weeks old, is nowhere to be found but
in the streams in which the old salmon had deposited their
spawn the previous winter, or in the immediate neighbourhood
of these streams. Early in April 1835, I found them in the
same stream as above stated, but so young and weak, from their
having but recently emerged from the bed in which the egg had
originally been deposited, as to be unable to struggle against
the stream, where there was any considerable current. They
therefore generally betook themselves into some small eddy, fre-
quently where the horses, in passing the ford, had left the im-
pression of their feet in the loose shingle of the stream, and in
this shelter, where there was a slight current, a few inches deep,
they continued to remain, with their little tails in constant ac-
tion, till my approach was perceived, when they immediately
darted under the stones and disappeared. At their first appear-
ance, they are only to be found under the loose shingly stones
two or three inches deep in water, with a very small current,
and close to the edge of their parent streams, or on the gravelly
bank sometimes called a scour or rack, which generally runs in
an obhque direction across the river, and adapts the stream so
admirably to the purposes of the breeding salmon, that there are
few instances of such scours occurring in the river without their
being much resorted to by the salmon during the breeding sea-
son. These httle fishes, as above stated, are to be found in
such situations during April, May, and even June ; but as they
increase in size and strength, they scatter themselves all over
the shallower parts of the river, especially where the bottom is
composed of fine gravel. The parrs of one year old, or summer
jwrrs, are now to be found in every considerable little current,
especially where the clear and shingly stream purls over the

and oil the Ova of the Saimofiu 103

scour, and terminates in tlie head of the pool, where, during the
whole summer, but more particularly in the montlis of August
and September, they are caught by the angler with a small fly
in prodigious numbers.

Having traced the progress of the little fish of one inch in
length, through its several stages of the parr up to the period
oi its migration, I may now communicate the result of my ex-
periments on the ova, to prove that I have not been mistaken
in my opinion that this fish is produced from the ova deposited
by the salmon the previous winter. On the 10th January 1836,
I observed a female salmon of considerable size (about 16 lb.),
and two males, of at least 25 lb., engaged in depositing their
spawn. The spot which they had selected for that purpose
was a little apart from some other salmon which were engaged
in the same process, and rather nearer the side, although still
in pretty deep water. The two males kept up an incessant
conflict during the whole of the day, for possession of the fe-
male, and in the course of their struggles, frequently drove each
other almost ashore, and were repeatedly on the surface dis-
playing their dorsal fins, and lashing the water with their tails.
Being satisfied that these were real salmon, there being at
least ten brace of that fish engaged in the same process on the
stream at the time, I took the opportunity of securing as
much of the ova as I could possibly obtain. This I did three
days after it was deposited, the males and female still occasion-
ally frequenting the bed. The method by which I obtained tlie
eggs was by using a thin canvass bag, stitched on a slight
frame formed of small rod iron, in fashion of a large square
landing-net, one person holding this bag a few inches farther
down the stream than where the ova were deposited, and ano-
ther with a spade digging up the gravel, (he current carrying
the eggs into the bag, while the gravel was in most part left be-
hind. Having thus obtained a sufficient quantity of the ova
for my purpose, I placed them in gravel under a stream of water
where I could have a convenient opportunity of watching their
progress. The stream was pure spring water. On the 26th Feb-
ruary, diat is, forty-eight days after being deported, I found
on close inspection that they had some appearance of animation,
from a very minute streak of blood which appeared to traverse

104 Mr Shaw's Experiments and Observations on the Parr,

for a short distance the interior of the e^g^ originating near two
small dark spots not larger at that time than the point of a pin.
These two dark spots, however, ultimately turned out to be
the eyes of the embryo fish, which was distinctly seen resting
against the interior surface of the egg a few days previous to
its exclusion. On the 8th April, which makes ninety days im-
bedded in the gravel, I found on examination that they were
excluded from the egg, which was not the case a day or two
previous. The temperature of the water at the time was 43'',
the temperature of the water in the river 45°, and the tempera-
ture of the atmosphere 39°. On its first exclusion, the little
fish has a very singular appearance. The head is large in pro-
portion to the body, which is exceedingly small, and measures
about Jive-eighths of an inch in length, of a pale blue or peach-
blossom colour. But the most singular part of the fish is the
appendage of a bag which adheres to the neck or upper part of
the belly. It is of a conical shape, the base being attached to
the fish. The bag is about two-eighths of an inch in length, of
a beautiful transparent red, very much resembling a light red
currant, and in consequence of its colour, may be seen at the
bottom of the water when the fish itself can with difficulty be
perceived. It also presents another singular* appearance, name-
ly, a fin or fringe, resembling that of the tail of the tadpole,
running from the dorsal and anal fins to the termination of the
tail, slightly indented. It does not appear that this little fish
leaves the gravel immediately after its exclusion from the egg,
but rather that it remains upwards of fifty days more under the
gravel with this bag, as a supply of nourishment during that
period, on the same principle as the umbilical supplies of other
embryo animals. By the end of fifty days, or the SOth May,
the bag disappeared, or rather contracted and formed the belly
of the fish. The fin or tadpole-like fringe also disappeared by
dividing itself into the dorsal, adipose, and anal fins, all of
which then became perfectly developed. The little transverse
bars, which for a period of two years (as I have shewn by ex-
periment) are to characterize it as the parr, have also appeared.
Thus, from the 10th January till the end of May, a period of
upwards of 140 days, has been required to perfect this fish, and
as yet it measures little more than one inch in length, and cor-

and on the Ova of the Salmon. 105

responds in every respect with the little fish on which I have
made my former experiment, as well as with those to be
found in the neighbourhood of the stream from which the
ova were taken, and where at this moment they are to be
found in great numbers. My observations have been confined
to the two or three fish which I dug up the day on which I
discovered they were hatched ; the others remaining undisturbed,
imder the gravel, until of late, when by removing the shingle
from off them, the perfect fish darted forth, and showed much
activity. The circumstance of their being dug from the gravel
a few days after their birth, does not appear to have affected
their health or progress, as those which I now take from the
shingle do not appear to be any farther advanced than those
which have been subjected to the annoyance of my weekly in-
spection ever since the 8th April. It is evident, however, from
the extreme difficulty the little fish has in dragging its unshape-
ly magazine of sustenance along with it, that nature does not
intend that it should be excluded from the gravel immediately
on its exclusion from the egg ; but rather that it should repose
in its birth-place under the gravel, with this bag, as a source of
supply until it be perfected.

It is well known to those who have paid any attention to the
fact, that the salmon begins to spawn in autumn, and, in many
rivers, continues to do so as late as the middle of February. It
is also generally known, that the salmon-fry in most rivers mi-
grate to the sea some time in May. But, be these facts as they
may, I can speak with certainty so far as regards the river
Nith, to which my experiments are chiefly confined. The sal-
mon spawning, so late as the middle of February, and the ova
remaining imbedded in the gravel for upwards of one hun-
dred and forty days, proves that they cannot all migrate in
May the same season the ova were deposited, as it must be the
middle of June before these can possibly make their appearance ;
yet it must be recollected, that those which were deposited iu
the earlier part of winter, are now to be seen in thousands in
the situations I have described, measuring, according to their
respective ages, from one inch to an inch and a half in length,
and certainly with no appearance of migrating.

The truth is, this little fish remains in the river all the first

106 Mr Shaw's Experiments and Observatioms on the Parr,

summer comparatively unobserved. It seldom takes the fly of
the angler the iirst season, and when it does, it forms so con-
temptible a prize that it is generally returned to the river; its
size not exceeding that of the common minnow. But by the
time it arrives at the age of twelve or thirteen months, the larger
parrs have disappeared as salmon-fry, which circumstance brings
this fisli more exclusively under the notice of the angler, and
thence originates the provincial name of May or summer parr.
All this considered, it must appear very extraordinary that it
should never have occurred to the intelligent angler to inquire,
what had become of the older generation of the parr, which was
to be taken in such abundance in the beginning of April, while
now (the end of May) there is no parr to be found in the river
exceeding tliree and a half inches in length, and these compa-
ratively scarce.

I have yet to communicate the result of another experiment
made on the ova of tlie salmon, interesting as well from its no-
velty, as from its tendency to corroborate in part the results of
the former. The experiment to which I allude was recom-
mended by Sir Humphrey Davy, as having been tried by him-
self, as well as Mr Jacobi, with perfect success. On the 8tli
January 1836, I had an opportunity of practising this experi-
ment, by taking a male and female adult salmon, whose appa-
rent weight was from sixteen lb. to twenty Jb. each, while in
the act of spawning. Preparative to my experiment, I dug a
trench in the gravel, through which I caused a current of water
to flow two inches deep. I then had the two living fish held in
this trench side by side, while with the hand I pressed the ova
and seminal liquor out of their bodies, which mixed freely to-
gether in the stream. A ^evf minutes after this process, I re-
moved the ova to a stream of water to which no other fish had
access, and on the 11th April, ninety-four days after the process
of artificial impregnation, the young fish was excluded from the
egg. They had precisely the same appearance in every respect
as those in the former experiment, with the exception of being
somewhat lighter in colour. Being, however, afraid of losing
them in this open stream, I removed them into a pond, where I
hope to be able to trace their progress still farther. It will ap-
pear from these experiments, that the ova artificially impreg-

and on the Ova qfifte Salmon, 107

nated have taken four days more to perfect the embryo thau
those impregnated in the natural way. However, this sUght
difiPerence in regard to time, may have proceeded from some im-
perfection in the process, or some little difference in the quality
or temperature of the water.

That the female parr docs not spawn is und^iable ; and al-
though the male parr of eighteen months old is to be found ia
the river, with the milt flowing from it in abundance, all the
winter round till about the end of February, yet no instance
has fallen under my observation of the roe in any female of the
same age, or indeed of any age, having advanced to similar ma-
turity. The female parr may be found in the river in autumn,
in nearly equal numbers to the male, but the roe found in it
has not the most distant appearance of approaching to maturity.
I have also taken it at times during the whole winter, when
the weather was mild, and still the roe had no appearance of ad-
vancing ; and even up to the period of their migration, it is to
be found with the roe in the same immature state. The male
parr having got rid of the milt, and therefore having no strong-
ly defined sexual distinction, has led many into the mistake of
supposing all parrs to be mules. By a minute examination,
however, there may be observed two very small reddish colouj-
ed vessels lying on each side of the swimming bladder, which
runs from the neck to the vent ; which vessels formerly contain-
ed the milt, but after its discharge have become very difficult of
detection, from their minuteness and transparency.

It has sometimes been maintained that the female parr has
been found in the act of depositing her spawn, but I am con-
vinced that those who have held this opinion have mistaken the
common trout for the par. Between the two tlie resemblance is
so close (both being marked with the transverse bars) as to be
a very probable source of error. If the parr was at all in the
i)abit of depositing its spawn in the river, or in its tributaries,
to which all small fish generally resort for that purpose, and if
we consider that nine-tenths of the small fish found in this part of
the river Nith are parrs, they must make some considerable
appearance when assembled on the streams, and therefore could
not escape observation. The apparent maturity of the organs of
reproduction in the male parr, and the decided immaturity of tlu?

108 Mr Shaw's Experiments and Observations on the Parr,

organs of the female of the same age, arc facts on which I could
not at present venture an opinion. However, from the specimens
which I have at present in my possession of tlie parr three years
old, that is, one year after assuming the dress of the salmon-fry, as
I have already described, I am prepared to shew that it is not a
mature fisli, as it continues to increase in size at about the same
rate it did previous to its disposmg of the milt, that is, at the
rate of three inches in twelve months, it being now nine and
a half inches in length.* I have found this rule to hold good
in regard to the growth of the parr, from observations on various
individuals found in the river Nith. Assuming the parr to be one
inch in length on its first exclusion from the ^gg, or rather from the
gravel in which the Qgg is deposited, it will be found to measure at
the same period the following year three and a half inches, and
when two years old it begins to be distinguished by the peculiari-
ties of the salmon-fry, and measures six inches. I do not mean to
assert that the size of the Nith parr is to be the rule for other
rivers, but as the parr in all rivers is admitted to be identical in
species, a corresponding rule will be found to hold good, what-
ever stream the fish may inhabit. I have found the male parr on
the streams in the winter during the time the old salmon were en-
gaged in'depositing their spawn, and on one particular occasion
in January last, I caught upwards of three dozen of them. On
examination I found these to be all males, and as they were all
congregated on the bed or red which the salmon had formed,
there is no doubt they were there for the purpose of feeding on
the ova as well as the aquatic insects dug up by the female sal-
mon, both of which I found in considerable quantities in their
stomachs ; but why there were no females found among them,
appears to me very mysterious, as they are certainly to be found
in other parts of the river the whole season, in pretty equal
numbers to the male. I have had, on three different occasions, an
opportunity of witnessing the return, or rather first migration,
of the salmon-fry to the sea in small shoals. The first of these
was in the first week of May 1831. I at that time had an op-
portunity of deliberately inspecting them, as the several shoals

• As this fish oufrht to have been in the sea twelve months ago, it cannot
be expected to continue increasing in growth in its present artificial situa-
tion.

and on the Ova of the Salmon, 109

arrived behind the sluices of the salmon-cruive, and while they
yet remained in the water, the indistinct transverse markings of
the parr were still to be seen, especially when they happened to
be swimming in a particular light, and occasionally as their po-
sitions happened to change, the bars became again imperceptible.
I also examined a number of them in the hand, and by holding
them at a particular angle to the eye, the bar could be distinct-
ly perceived, but if the fish was viewed with the broad side pre-
sented directly to the eye, this peculiar appearance could not be
recognised. Should all those methods fail, in shewing the cha-
racteristic bars of the parr on the salmon fry, it is only neces-
sary to remove the scales from the sides, and the bars will be
distinctly visible on the skin beneath. The next opportunity
which I had of witnessing the salmon-fry in their progress to-
wards the sea, was on the 3d May 1833. These had in every
respect the same appearance as those I have already described.
They passed down the river in families or shoals, of from forty
to sixty and upwards, their rate of progress being about two
miles an hour. The caution which they observed in descend-
ing the several rapids they met with in their journey was very
amusing. They had no sooner come widiin the influence of
the rapid current than they in an instant turned their head up
the stream, and would again and again permit themselves to be
carried to the very brink of the fall, and as often retreat, till at
length one or two bolder than the others permitted themselves
to be carried over by the current, when the whole, one by one,
disappeared, and as soon as they had reached comparatively
slill water, they again turned their heads towards the sea and
resumed their journey.

Qd, The third and last opportunity I had of witnessing them
migrating, was in May last (1836), when, as I have stated,
I compared a few of them with those which had assumed the
silvery dress of the salmon fry, after being in my possession
two years, in the character of the parr. The river, during this
month, being remarkably low, afforded me an opportunity of
ascertaining more accurately the time during which they have
continued to migrate, which has been nearly the whole of the
month, but more especially during the second week, in the
course of which the shoals were botli larger and more frequent

110 Mr Shaw'^s E.i'pervnents and Observations C7i the Parr.

in their successive arrivals. They had all the appearance of the
former, averaging from six to seven inches.

It must be admitted that my experiments and observations on
what I consider the young salmon have been confined to a par-
ticular locality, and therefore may not be entitled to the same
consideration as the opinions of a person of more extensive op-
portunity of research ; yet, as the parr is allowed to be the same
in all rivers, and, as it is universally admitted to frequent
those streams only to which the salmon has access, there can
be little objection to my facts on the score of confined locality.
That the small parr of one inch in length, found in April
amongst the loose gravel on the edge of the streams where the
salmon had spawned the previous winter, is the young of the
salmon, cannot, in my opinion, admit of a doubt. The facts
which I have related in the foregoing pages will supply the
deficiency of information so much complained of by most au-
thors in treating of the early history of the salmon, that is, the
progress of the fish from the egg up to the period of its migra-
tion ; and when it is recollected that the vertebrae of the parr
and those of the adult salmon correspond, and also that the parr
in its new dress cannot be distinguished in any respect from the
salmon fry, it may fairly be concluded that they are identical.
That the parr is not the produce of the common trout must be
evident to every one, from the circumstance of its changing its
appearance at a stated season, and then migrating to the sea,
a thing the common trout is never known to do. The diversity
of species is also corroborated by the fact, that the common
trout has never been observed to spawn in the stream where my
observations were made. Unless the trout be of large size,
which is not the case in the Nitb, it uniformly prefers the
tributary burns for depositing its spawn. Neither am I aware
of an instance of the sea-trout or the herling spawning on the
stream alluded to, these fish having generally proceeded early
in the autumn either towards the source or into some of the
tributaries.

A series of specimens illustrative of Mr Shaw's interesting
observations on the natural history of the parr has been pre-
sented by him to the Royal Museum of the University.— Ed.

< "1 )

Abstract of a Meteorological Journal for t?ie year 1835, Ice'pt at the Elgin

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( 112 )

Khifauni Meteoy-ological Table for 1835.

Extracted from the Register kept at Kinfauns Castle, North Britam.
Lat. 56° 23' 30"— Above the level of the Sea 150 feet.

1835.

January,....
February,...

March,

April,

May,

June,

July,

August,

September,..

October,

November,..
December, ..

Average of]
the year, J

Morning j past 9.

Mean Height of
Barora. Therm.

20.738
20.273
20.GI2
20.853
20.G13
20.837
20.735
20.732
20.348
20.413
20.G28
20.851

20.636

35.806
30.786
41.200
46.867
51.387
58.633
6O.774
6I.774
54.567
45.032
41.633
38.484

48.003

Evening, \ past 8.

Mean Height of

Barom. Therm.

20.735
20.280
20.620
20.866
20.613
20.844
20.745
20.734
20.326
20.446
20.631
20.861

20.643

36.032
38.500
38.200
44.233
46.548
54.333
55.120
57.120
52.800
44.484
40.233
37.410

45.427

Mean
Temp,
by Six's
Therm.

36.386
30.786
40.516
45.367
40.000
56.267
58.064
50.830
53.200
44.645
41.100
37.003

46.840

Depth
of Rain
in Gar-
den.

1.55
2.15
2.00

.50
2.00

.80
1.20
3.65
4.15
2.30
2.80
1.60

25.60

No. of days

Rain

or

Snow.

164

Fair.

22
U
16
24
9
10
17
18
12
10
12
22

201

ANNUAL RESULTS.

MORNING.

Barometer. Thermometer.

Ohservations, Wind. Wind.

Highest, . 2d Jan N.... 30.50 11th August,. ..W.... 70'

Lowest, . 3dFeb W.... 28.10 lOth January,. ..N.... 25°

EVENING.

Highest, . 2d Jan N.... 30.52 10th June, S 65"*

Lowest, . 24th Feb.. ..SW. 28.38 17th January,. ..W.... 23*

Weather. Days. Wind. Times.

Fair, 164 N. and NE. ... 37

Rain or Snow, 201 E. and SE. ... 84

S. and SW. ... 119

365 W. andNW. . . 125

365
Exlreme Heat and Cold by Six's Thermometer.

Coldest, . . . 21st Januarv, Wind W 20°

Hottest, . . 18th August, do. W 78*

Mean Temr.erature for the year 1835, 46°84

Results of Two Rain Gauges.
^ In. lOOths.

1. Centre of Kinfauns Garden, about 20 feet above the.Ievel of

the sea, 25.60

2. Square Tower, Kinfauns Castle, 180 feet, 25.75

( 113 )

Meteorological Observations made at Castl

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February,.

March,

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January,

February,

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September,

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TOL; XXI. NO. XLI. JULY 1836.

114 )

Abstract of Register of the Thermometer, Barometer and Rairu
Gatige, Tcept at Regent Terrace, Edinburgh, in 1835.

1835.

Thkrmombtkr.

RbgistbrThebm.

Barometer.

Quantity

of

Rain.

10 A. M . 10 p. M.

Min.

Max.

10 a.m.

10 p. M

January,

February,

March,

April,

38!84
41.01
42.77
47.97
52.29
57.90
61.29
62.19
55.00
47.32
43.90
40.39

37.48
39,07
39.19
43.53
46.35
52.07
55.23
57.55
61.90
44.23
43.10
39.19

34!l3
34.61
35.00
37.87
42.77
46.80
49.87
50.06
45.07
40.42
38.33
34.93

42^29
44.64
46.13
51.40
55.16
62.50
65.23
67.13
59.37
60.84
46.47
42.68

29.731
29.398
29.643
29.928
29.656
29.897
29.805
29.719
29.455
29.508
29.723
29.893

29.770

29.443
29.705
29.923
29.661
29.906
29.803
29.737
29.395
29.548
29.639
29.897

Inches.
1.08
2.48
2.28
.79
2.04
0.02
1.37
1.99
6.43
2.09
2.76
1.89

May,

June, ,

July,

August,

September, ...

October,

November, ...
December,....

Annual Mean

47.05

46.904

29.70

25.22

Meteorological Table, extracted from a Journal kept at Carlisle,
(above the level of the Sea 4}5JeetJ. By Mr Joseph Atkin-
son.

1835.

Mean Height of
Barometer.

10 a. m. 4 p. M,

Mean Height of a
Register Therm.

Min.

Max.

Quantity
of Rain.

January,....
February, . .

March,

April,

May,

June,

July,

August,

September,.
October,....
November,.
December,.

29.95
29.56
29.80
30.02
29.74
29.96
29.92
30.01
29.55
29.74
29.89
30.15

Average of the \
Year, /

29.925

29.95
29.57
29.81
30.01
29.74
29.95
29.91
30.00
29.53
29.77
29.87
30.13

29.92

34
38
37
43
45
51
63
66
49
44
40
36

43

40
45
47
64
69
68
70
72
62
63
47
44

65

3.1125
3.9405
2.5875
0.7375
2.2350
1.3200
2.9783
2.5490
6.2125
4.3650
3.3197
1.9718

34.3293

22
22
13
19
23
14
14
15
24
22
27
19

234

9

6

18

11

8

16

17

16

6

9

3

12

131

JOURNAL OF THE WINDS.

No. of days.
N. 8i

N.NE. 124
NE. 32
E.NE. 17

No of days.
E. 14

E.SE. H
SE. 161
S.SE. 20

No. of days.

s. 324

S.SW. 12
SW. 60^
W.SW. 62

No. of days.

w. m

W.NW. 5i
NW. 29

N.NW. 5

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Stormy Days.

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( 116 )

Annual Depth of Rain at Kendal in Cumberland^ from 1829 to
1835 inclusive. By Mr Wakefield. (Communicated to
the Magazine of Popular Science, No. 1.)

1829.

1830.

1831.

1832.

1838.

1834.

1835.

.Tnniinrv . .-.

Inches.

0.747
L234
0.867
3.511
1.977
4.204
5.569
9.383
5.243
6.684
3.855
2.899

Inches.
0.429
4.774
6.045
5.656
2.831
5.289
4.961
4.218
8.027
4.695

10.023
2.082

Inches.
1.619
8.208
6.208
2.433
0.721
2.682
4.081
3.899
6.393

11.812
8.560
4.980

Inches.
2.278
4.258
3.649
2.235
1.602
4.643
2.639
4.433
2.295
8.346
5.373
8.037

Inches.
1.628
4.682
2.070
3.754
2.534
7.715
2.233
1.966
3.527
3.752
7.438

14.219

Inches.

14.758
5.723
5.171
1.043
1.637
6.699
6.048
6.167
4.908
4.715
4.206
5.047

Inches.
6.349
8 820
5.049
1.589
3.063
1.254
6.259
3.107
7.815
4.386
6.311
2.889

February,

IMarch,

Anril,

Mav

June,

July,

Auerust

September,

October,

November,

December,

Whole Year,...

46.173

58.030

61.416

49.688

55.418

66.122

65.891

Mean depth of the Seven Years,
Total ditto,

65.962 inches.
391.738 do. or 32 feet 7| in.

On the Geology of Massa Carrara, By Professor Fkederic
Hoffmann.

The marble mountains of Carrara are situated in the north-
western part of the Apuanian Alp, a mountain group, rendered
very remarkable by the boldness of the forms of its rocks, and
still more by its almost complete separation from the chain of the
Apennines. This group extends about thirteen miles from south-
east to north-west, and has an average breadth of about six miles.
Towards the sea its acclivities are not very steep ; and Pietra
Santa and Massa are situated at the edge of an alluvial plain
which stretches to the foot of the mountains, and is about' 2 J
miles in breadth. This situation points out also very nearly the
termination of the two narrow and deep penetrating lateral valleys
of Senavezza and Frigido, To the north-west, in a sort of

S

J

g H

Professor Hoffmann on the Geology of Massa Carrara. 117

basin-shaped widening of the valley lies Carrara. The highest
summits of this mountain chain, the Pizzo cTUccelb and the
Pallia della brace, are not quite 5800 Parisian feet above the
level of the sea. On the side next the sea, talc-slate and mica,
slate are the oldest rocks which make their appearance ; they
dip regularly to the south-west, and in their lower beds, or in
the inner higher parts of the bottoms of tlie valleys of the Sena
and Frigido, pass into a distinct gneiss. Limestone masses oc-
cur very frequently throughout the whole extent of the slaty
rocks, and are particularly numerous and extensive in Senavezza.
Most of them are interstratified with the general arrangement
of the beds, and traversed by subordinate layers of slate which
run in a similar direction to the general stratification. They.alj
most all consist of a grey or nearly white crystalline-granular
limestone, veined or striped by lighter or darker colours, and
which is generally known by the name of Bardiglio. Besides these
regular interstratified hmestone masses, others appear in the slate
having less regularity, and greater variety of structure. The
largest of these is that which, completely surrounded by slate,
forms the Monte Altissimo on the north side of Senavezza, rises
to the height of upwards of 5000 feet above the level of the sea,
and whose south side forms towards the valley of the Sena a
rocky precipice 3000 feet in height. Here the limestone, jli
placed, like a long, obtusely acuminated wedge, between thfe
masses of slate. The gneiss turns suddenly round before this
limestone mass, under a very high inclination to the north-ef^sti
while the latter dips to the south-west ; on the bounding side of
the valley the junction of the two rocks is displayed in a preci-
pice of at least 1000 feet in height, and the bending of the gneiss
round the included limestone is distinctly visible. On the oppo-
site declivity of the AUissimo, and following the limestone are
the strata of slate, which are nearly perpendicular, or dip tp^
wards the limestone on the south-west. Still more remarkable
than this arrangement is the structure of the great limestone mass
of the Altissimo. Where the slate appears in contact with the lime?
stone, the latter is by no means a perfectly formed marble, but
is an impure ash-grey, fine granular, almost compact limestone,
which one would declare to be secondary lim^stone^ if he.did

118 Professor Hoffmann on the Geology of Massa Carrara,

not find it in such unusual connexion. Petrifactions were not
met with ; an ooUtic structure is sometimes, though rarely, ob-
servable. Usually the limestone is broken up into sharp-cor-
nered fragments by innumerable fissures, and when its sandy
looking granular structure is clearly exhibited, it looks like an
impure dolomite. Stripes occur resembling those of the Ranch-
wacke limestone. Farther in the interior of the mountain the
more or less considerable limestone and dolomite layer ceases,
and at last the beautiful brilliantly white marble commences.
The blocks of marble, still having a prismatic form, are always
surrounded by more or less considerable stripes of green talc-
idate abounding in iron-pyrites, which rock so completely en-
eases the niarble on all sides, and is so completely amalgamated
with it, that it almost appears as if the pure granular limestone
had been separated from the talc-slate in a liquid condition.
Where the latter penetrates the limestone, and does not separate
itself in distinct layers, impure coloured and striped Bardiglio
is generally produced. In the midst of the mass of pure, fully
formed marble, we not unfrequently see completely enveloped
traces of dark grey nearly compact limestone, having irregular
fissures, and so completely amalgamated with the including mass,
that we might easily regard them as fragments of the impure
limestone layer, upon which the altering action that produced
the marble could not complete the chaijge. To the east of both
the chief branches of the valley of Senavezza, in the valley of
Versiliu, the talc-slate dips at first at a high angle to the south-
west ; but where the deep lateral valley of Ruosina commences,
this position is changed. No gneiss appears under the slate,
and the last dips, in a direction up the valley, to the north-east.
At the Polite Stazzemese an impure grey limestone reposes on
the slate, and in all its relations reminds one exceedingly of the
external layer of Monte Altissimo. Upon it follows, towards the
C di Molina regularly superimposed, the peculiar marble,
known under the name Mischio d'l Senevezza, This mischio
exhibits a great number of sugar-like, granular, white lime-
stone fragments, included in a dark, iron red, compact clay-
stone basis, in ^vhich not unfrequently fine needles of hornblende
occur. At the planes of contact, the red coloiir of the uniting

Professor Hoffmann on the Geology ofMassa Carrara. 119

substance has also penetrated into the fragments, and fine scaly
green talc coatings are often to be observed. This brings to
our remembrance Savi's conjecture, that the peculiar marble
may owe its origin to a highly ferruginous vein of wacke having
penetrated into the limestone, — an occurrence which several ana-
logies point out. The red wacke veins of the mischio penetrate
like net-work the upper part, which runs in all cases parallel,
and consists of a pure white saccharine marble. This is changed
to Bardiglio in the superimposed mass, to which dark stripes
of mica running through it give a very beautiful watered ap-
pearance. Immediately above the quarries, which are carried
on to a considerable extent in the Bardiglio, the stripes of mica
are more crowded together, and form a stratum of distinct, well
characterized mica-slate. This, on the hanging side, becomes a
black clay-slate, upon which, in considerable quantity, and with
great regularity, a sandstone follows on the hanging side, which
is divided into beds of from one to three feet in thicknesS; and
often alternates with slaty marl ; and upon this sandstone lies an
extensive bed of limestone resembling rauchwacke. Near Staz-
zema, the sandstone becomes a fine granular quartz, and its
plates of mica become real slaty stripes. It alternates, at last,
in various ways with very considerable beds of pure clay-slate,
and above the whole series of strata, at a height of 1000 feet
above Strazzema, a distinct mica and talc-slate occurs, which
proves that we have not ye*^ left the region of the oldest forma-
tion of the chain. Similar conglomerated structures occur, in
various ways, subordinate to this slate formation ; but in no other
place are they so striking, and in such remarkable and peculiar
relations. This formation deserves particular attention, on ac-
count of its richness in metallic minerals in certain localities. A
mass of talc-slate to the south of Buosina is penetrated in all di-
rections by fine veins, and containing various sulphurets, vi^
lead- glance, blende, antimony-glance, iron and copper pyrites.
This circumstance is a strong argument for the original injection
and sublimation of metals in mountsuns. Veins of iron-slance
are abundant, and even cross in great numbers the veins of the
sulphurets ; large veins of red ironstone, magnetic iron, and iron-
glance occur also in the slate, and a vein of this description has
branched round the fissures of a bed of true Bardiglio, and has

120 Professor Hoffmann on the Geology of Massa Carrara,

confused and altered it. Out of the slate formation of which
we have spoken, there is only one limestone formation which
presents itself in any considerable quantity in the Apuanian Alp.
It rises to the height of 5728 feet above the level of the sea, in
the rocky cone of Pania della Croce, and in some places forms
walls which are frightfully perpendicular. On the great scale,
and on the whole, this limestone formation occurs always above
the slate. It is only along the declivity of the Tamhura ch^n,
which is directed to the south-west, that this position is reversed.
There the slate reposes regularly on the limestone, and one can-
not believe any thing else than that this steep elevated chain has
been overturned in its whole extent at the south-western edge.
The relations of the internal structure, and the occurrence of
the characteristic alterations of this limestone, render it difficult
to convey a distinct idea of it. On this account the author se-
lected the description of distinctly displayed sections, such as
those which occur in the mountain group of Carrara. Among
these there is no one so perfect and varied as that at the north-
west corner of the group, in the direction from Castelpoggio to
Tenerano. Castelpoggio is placed on the lowest beds of the
Macigno formation, which consists of red compact limestones
penetrated by oxide of iron, alternating with red and grey slaty
marls, which not unfrequently resemble old clay-slate. Here,
as in other places, the Macigno formation is traversed by veins
of quartz and calcareous spar, and very frequently blood-red
jasper and hornstone occur in nodules or thin layers. The dip
is to the south-west, under an angle of 48°. Under the Macig-
no commences next the rauchwacTce, which has a blackish-blue
colour, and is coarsely vesicular. Sometimes this rock loses its
porosity, and becomes a marble of an inferior description, or it
becomes a regularly stratified limestone, which not unfrequently
alternates with slaty marls, that have completely the appearance
of the layers of calcareous clay-slate which so frequently occur
with the old limestone in the German transition series. At the
junctions of the layers of limestone petrifactions occur, viz. small
species of Ostrea, Pecten, Cardium, Terebratula, and many
traces of corals. In the slates, bodies resembling scales of fishes
occur, and with them an Jvicula and a Corhula. Upon this
jmesione follows, about 600 feet under the pass, unstratified.

Professor Hoffmann on the Geology ofMassa Carrara. 121

vesicular, in general crystalline, limestone, which often seems to
indicate dolomite, and in the lower part passes gradually into
snow-white saccharine marble. Under the marble, and insensi-
bly encroaching on it, appear the mica and talc slates. With
these end the series of strata here observable ; for at the top of
the pass, an opposite dip of the strata takes place, and on the
other side, at Tenerano, the superimposed Macigno again ap*
pears. What this section in the Tecchia exhibits within nar-
row limits, is seen on a larger scale in all the cross ravines
of the mountain group of Carrara. In the central mass
further in the interior of the mountain group, the more or
less pure marble always occurs under the external limestone
layer. Its largest and purest mass lies near Turano, and
thence to the summit of the Monte Sacro. The talcslate is
connected with it in the same way as on M. Altissimo, and
divides the marble on the great scale into large distinct beds>
which are parallel to the general dip ; sometimes such separa-
tions of strata are indicated only by delicate scales of silverj
mica, or talc. This, hitherto termed primitive limestone, passes
gradually into compact vesicular limestone, abounding in petri*
factions, so that there can be no doubt as to the connexion in
their formation ; nay, even a perfect alternation takes place of
all these rocks. Between Carrara and Calonata, always pro-
ceeding in the descending order in regard to superposition, we
still find the porous and compact fossiliferous limestone, then,
where the valley of Miseglia begins, first a rock dipping under
a high angle to the south-west, an intermediate link between the
slaty marls of the secondary strata and the true clay-slate, and
this on the lying side passes into a beautiful talc-slate ; the talc-
slate forms a large pure layer, and is succeeded by an underlying
portion of beautiful white marble, veined with black. This
marble is followed again by an alternation of stratified black
limestone with slate, separated into plates one inch in thickness.
The slate is here more like mica-slate, and the limestone is more
rarely quite compact, and contains no petrifactions. Imme-
diately under this alternation of limestone, a slate follows the
great mass of the marble. Marble and dolomite are here one
and the same thing, and ascend uninterruptedly to the summit
of M. Sacro, If we go beyond this mass in an eastern direc-

122 Professor Hoffmann on the Geology ofMassa Carrara.

tion, we meet with, first, a dark grey compact or fine dolomitic
limestone, on which the whole mass of marble reposes, andocca-
sionally numerous layers and nodules of flint appear in the
Bardigllo-Yike limestone. In the upper part of the limestone
region of the Jpuanian Alp, we meet with numerous repetitions
and proofs of the relations described. It is only the pass over
the chain of the Tamhura which presents peculiarities. When
we have crossed the Tambura from the north-east, we leave, at
the bridge under Vagli di Sotto, the last trace of the Macigno
formation, which is cut through to this point from the valley of
the Serehio, viz. a fine granular sandstone. On the other side,
towards Vagli di Sopra, a compact dark limestone seems always
to occur again, a rock which is so often subordinate to the Ma-
cigno ; numerous veins of white, small, granular calcareous spar
traverse it, which soon predominate over the mass itself, and con-
vert it into marble. The numerous layers of slate in the mass of
the marble have always, towards the upper part, the character of
what Savi has called Galestro ; they are iron red, often also
green, and at the junctions of the layers there are the dull plates,
which generally occur in old clay-slates and secondary slaty
marls. Sometimes they contain more talc, become more shining,
and then resemble the old talc-slates ; sometimes they seem dull
and crumbling, so that one would be inclined to believe himself
transported to secondary rocks. Layers and nodules of jasper
are also not awanting. The marble, which is always so distinct-
ly divided into red beds on the great scale, is here everywhere
intimately connected with the layers of Galestro. It is inter-
ramified and interwoven with it. In the midst of the marble,
we meet with stripes and veins of rough vesicular limestone,
which passes into compact and into dolomitic limestone. At the
crest of the mountain chain lies a partly splintery, partly more
or less altered smoke-grey limestone, in which Guidoni found a
cast resembling a Turritella. Nearly the whole of the decHvity
of the Tambura chain towards the sea is decidedly dolomitic,
although very often the pure marble-like granular limestone
occurs in it. Under the Pizzo d'Uccello, the limestone is tra-
versed by veins of calcareous spar and quartz, and contains also
masses and layers of flint. Nearer Ajola, there are masses and
layers of a fine granular felspar, a kaolin-like substance, seldom

Professor Hoffmann on the Geology ofMassa Carrara. 123

well characterized ; but as to its mineralogical constitution, there
can hardly be a doubt, as not far from Ajola it occurs, alterna-
ting with the limestone in regular layers of from one to three
inches in thickness. In the larger portions of the felspar, iron-
pyrites occurs frequently, and also ironstone in veins. In the
neighbourhood of these substances, the limestone never alters its
texture, and invariably preserves its regular stratification. The
Macigno formation, which nearly surrounds the Apuanian Alp,
is a grey sandstone, which constitutes nearly the whole of the
northern half of the chain of the Apennines, and which has
hitherto been considered a greywacke. Numerous limestones,
divisible into groups, are subordinate to this sandstone. These
prevail chiefly round the Apuanian Alp, far above the sandstone
and its alternating slaty marls. The zone at the south-western
edge only, from Fosdinovo to Massa^ is entirely sandstone. The
remains of Fuci (especially the F. intrkatus) are characteristic
of this rock, and also of the limestone and slaty marl. The
sandstone formation everywhere reposes on the limestone ; and
where the Macigno is connected with the limestone, the two
seem most intimately united. The great resemblance, and the
direct union of the Galestro, and the older limestones reposing
on the slate, and even the old mica and talc slates, prove this
fact in the most perfect manner. Where the jNIacigno formation
consists chiefly of limestone, it is often hardly possible to assign
with precision the boundary of the two formations ; for their dip
is always the same, and the external resemblance so great, that one
might reasonably consider them as formations passing the one
into the other.

The Macigno formation, notwithstanding its enormous extent,
and the peculiar character of its component rocks, is a geognosti-
cal equivalent of the great formation of the north of Europe,
the Chalk and Greensand, Its relations in position hitherto
observed, are in favour of this view. In Sicily, where this for-
mation is displayed in all those peculiarities which distinguish it
throughout the whole of Italy, the author was often surprised
by the completeness through a great extent, of the uniform
transition to the tertiary series. It is also rendered more pro-
bable by the repetition of the same circumstance in very
numerous points on the Italian continent. The immediate

124 Professor HofTniann on the Geology of Massa Carrara.

neighbourhood of Geneva presents many such examples, and
the observations of De la Beche on the environs of Nice, are of
decisive importance on this subject. It is consequently very
probable, that the limestone of the Apuanian Alp, which imme-
diately follows the Macigno, is to be considered as a Jura lime-
stone ; and we must then, as Savi has recently done, refer the
lower layers to the Macigno formation, a view which the author
does not consider as the correct one. It is certainly very sur-
prizing to find rocks like those described, clay and mica slates,
talc-slate, and gneiss, which leave no doubt as to their being con-
temporaneous or intimately connected with fossiliferous lime-
stone of the newer secondary formations. The slates follow not
only directly in entirely uniform connection with those lime-
stones, but they penetrate them, alternate with them, and are so
intimately blended with their masses, that the author considers
them even undoubted members of the secondary series. To
which of the known members of the secondary class these slates
are to be referred, we do not yet possess sufficient facts to enable
us to determine. The chief difficulty seems to be particularly
in the completely altered condition of the limestones. The mar-
ble, whose occurrence seems so remarkably connected with its
intimate union with the slate is certainly a limestone altered
by Plutonic agency. This we could not doubt, even though
the numerous relations of its union with dolomite and vesicular
limestone, its transition from compact and still unaltered lime-
stone, its penetrating veins, &c. were not observable. If, how-
ever, these altering actions have been produced through the
medium of the interlacing of the slates with the limestone, the
conclusion that the slates must have undergone alteration and
change cannot be avoided

The only distinct unaltered members of this slate formation,
seem to be the Macigno-WVQ sandstone and the slaty marl of
Stazzema, and perhaps also the clay-slate occurring in its vi-
cinity ; as to whether these rocks at one time belonged to the
series of the Jura or Keuper formation, the phenomena now un-
der consideration afford no explanation. Mica and talc slates
are decidedly products of a deeply penetrating altering action,
and their connection with the gneiss inclines the author to be-
lieve that the probably long uninterrupted action to which all

Professor Hoffmann 07i the Geology ofMassa Carrara, 126

those altered rocks have been exposed, was accompanied by the
uprising of a granitic mass, which in this district did not remain
far under the bottom of the deeply-seated valleys. The whole
process, according to the facts deduced directly from observation,
took place very probably in the oldest period of the formation of
the chalk, for even the oldest strata of the Macigno, those re-
posing directly on the Jura limestone, are distinctly altered and
converted into Galestro. In the newer strata, we find not un-
frequently enclosed fragments of shining mica and clay slates,
which have been produced by the processes described. Mica
and talc slates and the marble altered from limestone, appear to
the south in the far projecting Promontorio Arge7UarOy in the
mountain group of Campiglia, and in the island like separated
Monte Pisani ; and to the north of the Apuanian Alp, there is
that mountain chain which surrounds the Gulf of Spezzia which
presents a very perfect representation on a small scale of the
phenomena we have described. Of the granite whose eruption at
this last period of its formation probably produced all these ap-
pearances, we know almost nothing in this part of the mainland
of Italy ; it is said to occur at Campiglia, and there only. What
is here concealed under the surface, is displayed rising above
the sea in an immense mass in Elba ; and a recent examination of
that island made by the author proves that there the granite
which forms mountains more than 3000 feet high, is intermixed
with the older limestone of the Apennines (under the Macigno),
and converts it by direct contact into marble. It is highly pro-
bable, that phenomena analogous to those ascribed to the action
of the granite in the district described, have in the Apennines
been produced by the out-break of the Galestro, whose appear-
ance must have followed immediately the completion of the
great Macigno formation.

( 126 )

1. Observations on the Annular Solar Eclipse which occurred
on the 15th of Mai/ 1836, by William Galbraith, Esq.
2. Observations on the Eclipse, by Commander Alexander
Milne. 3. Observations made with LesUe'^s Photometer
during the Eclipse, by E. Sang, Esq.

An eclipse of the sun, it is well known, is caused by the
body of the moon coming between the spectator on the earth''s
surface and the sun, thereby producing a greater or less de-
gree of darkness according to the magnitude of the eclipse.

In the early ages of the world, men were either ignorant of,
or at least not well acquainted with, the natural causes on
which these phenomena depend ; and consequently they were
then regarded with superstitious awe, but now they are hailed
with satisfaction as phenomena highly valuable for the pur-
pose of improving our knowledge of astronomy, geography,
and navigation. On this account some of our most zealous
practical astronomers travelled hundreds of miles in order to
observe this eclipse to the greatest advantage.

Those observers here who felt an interest in these depart-
ments of science, continued for some time previously to pre-
pare to observe it as effectively as their circumstances would
permit ; and in several instances within our knowledge this
was satisfactorily performed, and the agreement in the results
almost as close as could reasonably be expected.

Throughout Europe the same vigilance will doubtless be
manifested, from which a mass of observations must be ob-
tained that will at this epoch fix with extreme precision the er-
rors of the lunar tables which have already attained so high a
degree of accuracy, by the labours of those astronomers and
mathematicians who have done so much for the advancement
of their favourite science.

My observations were made within the grounds of the obser-
vatory of Edinburgh on the Calton Hill, in Lat. BS"" 57 22'\5 N.,
Long. 12"^ 43^5 W., as deduced from previous observa-
tions ; and these I believe to be within the limits of admissible
errors inseparable from observations. The instruments used
were an inverting telescope, magnifying about fifty times, and a

Ohservatixyiis on the Annular Solar Eclipse, 127

pocket chronometer of the usual construction, making five beats
in two seconds. This train is not so convenient for estimating
fractions of seconds as a clock beating exact seconds, or a chro-
nometer making exactly two or three beats in a second, and
consequently I was unable to mark parts of seconds satisfacto*
rily. The chronometer was set to mean solar time a little be-
fore the commencement of the eclipse, and lost two seconds, as
nearly as could be estimated, during the continuance of the ob-
servations, when compared with a clock whose error had been
ascertained that day by direct observation. On allowing a pro-
portional part of this rate to each observation, fractional parts
have been introduced whose accuracy is not warranted to nearer
than half a second of the truth of the time of the phase intend-
ed to be recorded.*

Having made these preliminary observations and explanatory
remarks, I shall now state the final results in mean solar time.

u. M. s.

The first contact of limbs took place at . 1 33 9.75

Annulus completely formed, . . 2 57 21.12

Annulus broke . . . . 3 1 11.03

Termination of the eclipse. . . . 4 19 22.40

From a mean of the times of the commencement and termi-
nation of the annulus, I infer that the time of greatest obscura-
tion took place at 2^ 29"* 16^07, and from the difference of
those times that the annulus lasted 3™ 49^91. It may be add-
ed, that all the observations here recorded having been taken
with equal care, and no oversight having occurred or accident
happened in the management of the instruments, they are all
entitled, in the opinion of the observer, to equal confidence.

These observations, when compared with others made on dif-
ferent meridians, will give the difference of longitude between
those meridians with great accuracy, though for ordinary prac-
tice the calculations are rather long and difficult to persons not
much habituated to such operations. Taking the sun's and
moon's places as given in the Nautical Almanac, which are de-
rived from tables known to be liable to small errors only, the
longitude of places may be obtained to a considerable degree of
precision. On this principle, by the rules and formulae which

• Different observers even at the same place will occasionally, in these
kinds of observations, differ some seconds.

128 Observations on the Annular Solar Eclipse,

are well known, I have found the longitude of the place, by my
observations of the beginning of the eclipse, to be IS"" 22s.26 W.
and by the end 12"' 41 ^6 W. The first of these deviates about
20« from the truth, the second 2' only, and the mean of
both about 11% arising from the errors in the solar and lunar
tables combined with the errors of observation. When the ob-
servations made at the Royal Observatory of Greenwich, and
other places whose longitude is well determined, are obtained,
a comparison of these will fix the longitude of my station with
greater certainty ; though from the results above it is clear that
in distant countries, where corresponding observations cannot
be often got, the longitude may in this manner be found, by
repeated observations, to a very great degree of accuracy. In
observing eclipses, the complete phase is generally that most
attended to, because the precise time of peculiar intermediate
states is not easily attained. I had originally proposed to
mark the time when the ring was partially formed, and only
broken occasionally by the lunar mountains, but I found some
uncertainty ift determining that state of the eclipse. By sweep-
ing the eye along the serrated limb of the moon, I could not
determine precisely the mean level of the moon's surface, or the
circular line equidistant from the centre, and I was therefore
doubtful whether the parts of the limb of the sun broken by.
dark intervening spots, were entirely mountains or not ; and the
short space of time allowed for consideration did not permit me
to come at any conclusion by reason and reflection. The esti-
mated time in some cases, from the light first breaking through
what might be readily taken for valleys at the point of nearest
contact, till the luminous arch reached the summits of the moun-
tains, at both the formation and termination of the ring, taken,
of course, in inverse order, was about five seconds, more or less,
in my judgment, according to circumstances; but I have not
recorded these among what I conceive to be decidedly good ob-
servations. I marked the time of entrance of some of the spots
too, but as these observations also must be very vague, I have
not communicated them.

These broken particles of light, already alluded to, intersect-
ed by the serrated peaks of the lunar mountains, produced a
very interesting and brilliant effect, and had a good deal of the
appearance of elongated particles of mercury arranged in a nar-

Observations on the Animlar Solar Eclipse. 129

row circular groove, divided by small dark ridges lying between
them. It might have been remarked sooner, that there appear*
ed to the eye a darkish space very near the sun'*s limb about the
point of contact, just before I was fully assured that the con-
tact had absolutely taken place, and, something to my appre-
hension, to a certain degree resembling the rotatory or spiral
motion of dust caused frequently by the wind in our streets in
dry weather, but whether it was more illusory than real, I shall
not at this time take upon me to determine. A comparison of
my remarks with those of other observers, will, it is hoped, tend
to verify or correct them. •

I shall not attempt to describe the effect which the darkness
had upon nature generally, because that though I could take a
glance at the surrounding scenery occasionally, my mind was
too much occupied with other pursuits to do it carefully. I saw
Venus distinctly with the naked eye, but could not perceive
either Jupiter or Sirius, because my eyes were too much affect-
ed with the constant glare of the solar rays, though viewed
through a pretty deep-coloured glass, to distinguish any other
objects accurately. I did what I could, though placed not in
the most favourable circumstances, to observe the more striking
phases of this interesting and important phenomenon with all the
accuracy in my power, but with what success an extensive com-
parison of them with those of others will determine.

54. South Bridge, Edinburgh,
May 15. 1836.

Observations on the Annular Solar JEclipse. By Alexander
Milne, Esq. Commander R. N., F. R. S. E., in a letter to the
Editor, Professor Jameson, dated at Inveresk, near Edinburgh,
May 1836.

The general aspect of the morning of the 15th May was un-
favourable, and yielded but little prospect of a clear day for
viewing the eclipse. The wind was strong from the westward,
—the sky overcast, and a dull haze pervaded the western hori-
zon. Towards ten o'clock, however, all these symptoms which
foreboded disappointment vanished. The clouds had already
become partially broken, and the sky soon afterwards became
clear, while the sun shone forth warm and briUiant, dissipating
the still lingering remains of the morning vapours.

VOL. XXI. NO. XLI.-— JULY 1836. I

130 Observations on the Annular Solar Eclipse

The chief object to which I had proposed to direct my atten^
tion, and observations, was the effect which the progress of
the eclipse produced on the thermometer, not only in the shade,
but likewise when subject to the influence of the solar rays.
.With this view four thermometers were carefully compared with
each other, that the observations might be reduced to one stan-
dax'd. One of these instruments was placed in the shade, sub-
ject to the aspect of a northern sky, and so placed as to be under
no influence of local radiation, being solely affected by the aerial
temperature ; — whilst another was suspended also in a free cir-
culation of air, but at the same time in the solar rays.

The other two instruments were subject to experiment under
the direct influence of the solar heat, being enclosed in a box
having a glass cover, to insure protection from aerial currents.
The bulb of one was enveloped with a covering of black silk,
with the intention of increasing the range of that instrument,
and thereby more correctly detecting the loss, as well as increase
of heat during the progress of the eclipse. These instruments
were invariably kept directed to the sun.

These being prepared, and the sun clear, the observations
were commenced, and continued at intervals as noted in the fol-
lowing table.

In the Box

a

t3

1

In the Box

1

1

Mean
Solar

exposed tx>
Solar rays.

1
•^

1

Remarks.

Mean
Solar

exposed to
Solar rays.

1

Time.

Black

Plain

1

1

Time.

Black

Plain

1

1

Bulb.

Bulb.

77

5

a

Bulb.

Bulb.

C

a

10^45'

95

81

Sky clear, although

2h43'

781

75^

604

571

U

98

78i

82

58

still some partial
haze.

2 55

73^

72

59^

57"

11 30

99

84 1

94|

...

3

69-

661

581

...

11 45

107i

102|

74

60

3 6

67^

65|

58"

56

Noon.

121

106|

72^

60^

Sky perfectly clear,
ana continued so

3 10

fe>

fc>

571

55|

12 15

12U

107

72

60

until 4 h. 20 m,

3 16

70

661

571

551

12 30

120^

106i

711

60

3 21

74

s^'

584

55|

12 45

118|

1031

73^

601

3 30

84

731

591

55|

1

121^

107

76l

60 1

3 35

84^

77"

60|

56

1 15

121|

106|

75|
73

611

3 43

88 1

80

611

56

1 28

123

108

3 52

944

84

6H

561

1 40
1 50

120i
117^

106a
104

70^

67i

TheBarom. atlOOfeet
above the sea re-
mained stationary

4 2

4 12

m

103

901

60|
651

564

57i

2 2

112

100|

67

60 L

at 30.549.

4 20

1031

92

651

57^

2 12

105 Is
100

95

64a

60^

4 35

103

92

64t

57^

2 23

92

64^

591

4 50

92

83^

61 1

^n

2 35

90^

84i 621

58|

J

zj

Observations on the Annulcir Solar Eclipse. 131

From the above tabulated results it will be observed, that from
the first period of observation (10^ 45™), the instruments in
all their relative situations gradually rose in temperature, until
jh ggm^ jj|- ^vhich time they had obtained their maximum point,
except the one exposed to the air and sun's rays, whose indica-
tions were influenced by passing currents of air by which it was
at intervals depressed. At 1^ SS'^.T the moon's limb was ob-
served to enter on the solar disc, and a few minutes after that ob-
servation the thermometers were noted. Those in the box under
the direct influence of the solar heat, had already become de-
pressed ; while that in the northern shade remained stationary
until near two o'clock, when it also indicated a depression. The
three exposed to the sun's rays had continued their progressive
descent from the commencement of the eclipse.

At 3^ the annular phase was central, and the instruments
most clearly indicated an extensive depression from the time
of the first contact of the limbs, and still continued to fall
until some minutes after that hour, when those exposed to the
solar rays attained their minimum temperature ; not so, how-
ever, the thermometer in the shade, whose indications of its
lowest point did not occur until 3*^ 16^.

The annular phase having ended at 3^ S'^.S, and the body of
the moon withdrawn itself from the sun's disc, so as to permit
the intercepted rays to fall to the earth, the instruments quickly
indicated the change, and continued to rise as the eclipse passed
off*. They attained their second maximum at 4*^ 24™, the time
at which the eclipse ended. The sky now became partially over-
cast with thin attenuated clouds, dispersed over the solar disc,
and intercepting the solar radiation, farther experiments were
therefore discontinued. It may, however, be mentioned, that
during the time of the eclipse, and whilst the observations were
recorded, the sun presented a uniformly clear disc, and the atmo-
sphere remained as nearly as possible in the same state.

Abstract of greatert and leaft Temperature.

In the Box.

Air in
Sun's
rays.

North
shade.

Black.

Plain.

Greatest 1 28

Xeast3»»6

Difference .

123

C7J

108
C5i

73

o74

61^

55^

bb\

42i

15^

5|

1%

*32 Observations on the Anmdar Solar Eclipse.

It must, however, be remarked, that the greatest temperature
in the shade as indicated at 1^^ 50"% is by no means the great-
est temperature for the day, as it generally attains that point
between the hours of two and three o'clock. With the object of
attaining the hour of maximum temperature, some observations
were instituted for the purpose. The sky and aspect of the day
being in close resemblance to that of the eclipse, it was found
that the same instrument in the shade indicated its maximum at
S^ SO™, and having become stationary at 69^. The tempera-
ture at 1^ S8'" of the same day being 66^, we may therefore at-
tain from these observations an appj'oaimate temperature for
the period of greatest obscuration, or of least temperature on the
15th. This we may assume at 64, whilst that actually observed
was 55^, there being a difference of 8 J. This difference, there-
fore, may be assumed as a close approximation to the loss of
heat ill the shade by the interception of the solar radiation.

Observations on this beautiful phenomenon were directed not
only to the changes of temperature, but also to the progress of
the phases, and the following are the results expressed in mean
solar time, at the place of observation, which was at Inveresk,
near Musselburgh, in latitude 55° 56' W N. ; longitude
3° 2' 40'' W.

h. m. s.

First contact of the limb, 1 33 44

First do. of the annulus, . . . . . . 2 57 56.5

Last do. of th2 annulus, 3 2 34.5

Last do. of the limbs, 4 19 52

Occultation of the Spots on the Solar Disc,

h. m. •.

Spot on sun's western limb, . . . . (a) 1 40 3

Large well-defined spot towards sun's centre, . {b) 1 52 47 .

Small spot near lowest cluster, . . . . (c) 1 13 44.5

Small spot under the large one, . . . . (rf) 1 14 45.6

tTppermost of two single spots above the large one, {e) 1 33 9.5

Large spot of the upper cluster, . . . . (/) 2 22 16.5

Emmersion of large spot, 3 33 33

Emmersion of spot (e), 3 34 41

On surveying the solar disc before the commencement of the
eclipse, it presented a numerous collection of spots, chiefly con-
fined to the west of the sun's centre, and dispersed vertically in
an irregular form ; some of them were single, having the ap-
pearance of a dark nucleus, with a well-defined edge, and sur-

Observations on the Annular Solar Eclipse, 133

rounded with a faint cloudiness, which appeared parallel to the
interior nucleus. In this encircling band which surrounded the
largest spot, were observed several small dark specks, in colour
resembling the interior nucleus itself; others were formed into
groups and clusters, and dispersed on various parts of the sun's
western disc.

Several seconds (6 to 10) before the formation of the annulus,
a faint light was perceptible encircling the moon"*s limb before it
advanced on the solar disc. This light gradually preceded the
horns or cusps of the sun, as they approached each other, from
the moon's progressive motion. Small detached portions of the,
sun's body were also observed around the lunar limb imme-
diately before the formation of the annulus, an appearance pro-
bably owing to the rugged or uneven surface of the moon's body.
At this time the darkness which prevailed, was certainly not
so great as was expected. Venus alone was distinctly visible, Ju-
piter could with great difficulty be distinguished, and none of
the fixed stars could be observed. It was interesting, however,
to trace during the continuance of the eclipse, and while the
darkness gradually increased, the various characteristic changes
which were produced. The peculiar dimness of the light ema-
nating from the half-obscured sun, or when it alone exhibited
a narrow ring, resembling the peculiar light afforded by the
moon in tropical latitudes. The various rays of light as they
penetrated through the foliage, gave faint and undecided sha-
dows, while they presented the peculiar crescent form of the
eclipse itself. These, however, were not the only points which ac-
companied this unusual and beautiful phenomenon. Nature,
both animate and inanimate, was equally influenced by the ap-
proach and progress of the darkness ; — for as the penumbra gra-
dually overspread the place of observation, the birds took up for
a moment their evening song ; but speedily, as if alarmed by the
unusual character of the twilight and its chilling coldness, ceased
their notes, and became silent and motionless. Vegetable crea-
tion participated also in the general and universal change. The
wild anemone, which shortly before was fully expanded, now
yielded to Nature's laws and closed its leaves as on the approach
of night; whilst a night-flowering plant in the greenhouse, ia .
accordance with the laws of their peculiar constitution, opened

134 Observations 07i the Annular Solar Eclipse.

its ball-formed flowers. But these phenomena continued only
for a moment. The eclipse completed, and the sun's light and
heat radiating once more on universal nature, every object seem-
ed to participate in the cheering change. The flowers which
had closed, soon yielded to the reviving influence, and expand-
ed dieir flowers and leaves ; while those whose natural time of
bloom is only during darkness, closed them until the approach
of the natural evening. The feathered tribes, as if released from
some mysterious thraldom, were again immediately on the wing,
and pursuing their wonted and busy occupations ; the whole
machinery of nature, in short, which for a few minutes seemed to
stop, or at least to be retarded in its movements, again resumed
its working, and was beheld in the possession of its wonted
energies.

Observations made with Leslies Photometer during the Annular
Eclipse. By Edward Sang, Esq^

The predictions of great darkness which were current before
the eclipse were not at all warranted by the computations ; du-
ring the continuance of the ring, about one-eighth part of the
sun's disc was to be exposed, an extent quite sufficient to afford
light equal to the ordinary illumination about sunset. A bright
sun at noon of a summer day gives an indication of about 150°
of Leslie's photometer, and at three o'clock we might expect
nearly as much ; the eighth part of that is 17° — eight or ten
times the illumination of a well-lighted room. If the sky had
been covered with thick clouds, the light, during the greatest
obscuration, might have been reduced to a single degree, which
still, however, would have been sufficient to allow of reading a
small print.

The observations made on the roof of the New Buildings,
North Bridge, fully bore out these expectations. There the in-
dications of an excellent photometer were noted every five mi-
nutes. Just before the eclipse began the light was 141° ; at
the time of the greatest obscuration it fell to 12J° ; just before
the eclipse terminated some thin clouds disturbed the observa-
tions ; just before they appeared the photometer shewed 117°;
after that it sunk to 86°, and rose six minutes after the eclipse
terminated to 120|°.

Ohservatlons on the Annular Eclipse.

135

The following table exhibits the results of the observations :—

Time.

Phot

Remarks.

rime.

Phot. Remarks.

OH

SO"*

136*

sky clear.

2h

40to

69*

55

139

2

45

48

140

2

50

85

6

140

2

65

20

10

141

3

12 eclipse annular

13

140

3

5

16

20

141

3

10

26

25

141

3

15

37

30

141

3

20

47

33

(

scllpse began.

3

25

67

35

141

3

30

64

40

138

3

35

73

45

138

3

40

80

60

136

3

45

101

55

129

3

50

107

2

124

3

55

114 light haze.

2

5

119

4

117

2

10

110

4

6

114 cloud.

2

15

106

4

10

113 cloud.

2

20

92

ight cloud.

4

15

86 cloud.

2

25

89

4

19

eclipse ended.

2

30

77

4

20

105

2

35

69

4

25

120

From this table it will be seen, that so soon as the sun began to
be concealed, the instrument indicated a perceptible diminution
of light, and that its readings followed very closely the progress
of the eclipse. The transparency of the air, however, was sub-
ject to considerable fluctuations, the effects of which are percep-
tible on the numbers. After the greatest obscuration the indi-
cations rise, but not with a rapidity equal to that of their de-
scent, for this reason, that as the sun was getting lower, his rays
had to traverse a greater thickness of atmosphere.

The diminution of heating power, as shewn by the photometer,
was 129° of its scale, that is, 12°.9 of the centigrade thermome-
ter, or 9S\ of t)>e common Fahrenheit thermometer.

Instructionsjbr Making and Registering Meteorological Obser^
vations at various Stations in Southern Africa and other
Countries in the South Seas, as also at Sea.*

The great importance of possessing an exact and carefully
registered account of the variations of the barometer, thcrmo

* Drawn up for circulation by the Meteorological Committee of the South
African Literary and Philosophical Institution ; we believe by Sir John
Herschel. The "Instructions" are printed in No. 1. of Second Series of
the South African Quarterly Journal, sent to us by our friend Dr Adamson
of the Capa

18^ ■ Instructions for Making and Registering

meter, and other meteorological instruments, and of the winds
and weather throughout that extensive region of the Southern
Hemisphere, which is either included within the boundaries of
this colony, or readily accessible from it, has determined the
South African Literary and Philosophical Institution to request
the assistance of its correspondents, and of all who may have
leisure and inclination for observations of the kind, towards the
gradual accumulation of a continued and extensive series of me-
teorological Journals, and towards carrying into effect a concert-
ed plan of contemporaneous observations, on stated days, from
which it is conceived that much advantage will be derived. The
institution therefore solicits the attention of its correspondents,
and of the lovers of knowledge generally, to this object ; and
earnestly requests their co-operation in making, arranging, and
forwarding to its secretary, resident in Cape Town, observations
of the nature ; and, so far as practicable, according to the plan
of those hereafter detailed. Such observations alone can furnish
the materials necessary for an accurate and scientific inquiry
into the laws o{ climate, regarded as an object of local interest,
and are the only data through which (taken in conjunction with
the known laws of physics), the more general relations of meteo-
rology can be successfully investigated.

It can scarcely be necessary to insist on the practical import-
ance of this science to the agriculturist, to the navigator, and in-
deed in every branch of human affairs, or to dilate on the bene-
fits which must accrue to mankind in general, from any success-
ful attempts to subject to reasonable and well-grounded predic-
tion the irregular and seemingly capricious course of the seasons
and the winds ; or on the advantages, purely scientific, which
must arise from a systematic development of laws exemplified
on the great scale in the periodical changes of the atmosphere,
depending, as they do, on the agency of all the most influential
elements, and embracing in their scope every branch of physical
science. It is more to the present purpose to observe that, from
what has already been done in this department of human know-
ledge, there is every reason to hope that no very distant period
may put us in possession of the key to many of the most intri-
cate meteorological phenomena, and enable us, though not to
predict with certainty the state of the weather at any given time
and place, yet at least to form something like a probable conjee-

Meteorological Observations. 137

ture as to what will be the general course of the next ensuing
season — perhaps to prepare us beforehand for violent and long-
continued gales of wind, great droughts, or extraordinarily wet
seasons, &c. in the same manner that our knowledge of the na-
ture and laws of the tides, although confessedly imperfect, and,
in a great measure, empirical, yet enables us to announce, be-
forehand, unusually high or low tides. No doubt such predic-
tions of the weather, although only of a probable nature, would
be highly valuable and useful, and would materially influence
the practice of men in all operations thereon depending. In iUi
lustration of this, we need only refer to the value set by many-
farmers and others on weather-tables, founded on no sound prin-
ciples, and ratified at best, if at all, only by a very partial and
limited experience ; or, to choose a better instance, we may cite
the importance which is now attached by every seaman to the
indications of the barometer, and the numerous cases with which
nautical records abound, of great mischief, or even shipwreck,
avoided by timely attention to its warnings.

Meteorology, however, is one of the most complicated of all
the physical sciences, and that -in which it is necessary to spread
our observations over the greatest extent of territory, and the
greatest variety of local and geographical position. It is only
by accumulating data from the most distant quarters, and by
comparing the affections of the atmosphere at the same instant
at different points, and at the same point at different moments,
that it is possible to arrive at distinct and useful conclusions.
Hence arises the necessity of procuring regular series of obser-
vations made on a uniform system, and comparable with them-
selves and with each other, by observers at different stations, and
of multiplying the points of observation as much as possible over
the interior surface of continents — along sea-coasts — in islands
—and in the open ocean.

The geographical position of this colony renders it perhaps
the most interesting and important situation on the surface of
the globe for observations of this nature : first, whether we re-
gard it either as an advantageous station for observing the com-
mencing action of the great counter- current of the trade-winds,
where it first strikes the earth''s surface, and, combined with the
action of the heated surface of the African Promontory, gives

] 38 Instructions Jor Making mid Registering

rise to that remarkable alternation of south-east and north-west
winds, which forms so distinguishing a feature of our climate —
or consider it, secondly, as the farthest extremity of one of the
two great lobes of land which form the terrestrial part of our
globe, and as such, constituting at once a barrier to the currents
and tides of two great oceans, and a limit to their climates — or,
lastly, as a great nautical station, and one not devoid of diffi-
culty and danger, in which every consideration of practical inte-
rest combines to stimulate the curiosity of the theorist, and give
importance to the results of his inquiries.

As these pages may fall into the hands of many who have
been little in the habit of observing systematically, or who may
not be in possession of instruments of the nicest construction, at-
tention to the following instructions is recommended as the means
of rendering their observations most available for useful purposes,
and comparable with each other, and, with those intended to be
refered to as standards.

I. General Recommendations and Precautions.

1. The continuity of observations ought io be interrupted as little as pos-
sible hy changes in the adjustments of instruments — in their places — expo-
sure — mode of fixing— or of reading off and registering them. Whenever
any alteration in these or any other particulars takes place, especially such as
are likely to affect the zero points, or otherwise to influence the mean re-
sults, it should be noticed in the register.

2. So far as possible, registers should be complete — but if by unavoidable
circumstances of absence, or from other causes, blanks occur, no attempt to
fill them up by general recollection, or by the apparent course of the numbers
before and after, should ever be made.

3. The observations should, if possible, all be made by one person — but as
this may often be impracticable, the prmcipal observer should take care to
instruct one or more of his family how to do it, and should satisfy himself b}-"
many trials that they observe alike.

4. The entries in the register should be made at the time of observation,
and the numbers entered should be those actually read off on the respective
scales of each instrument, on no account applying to them previous to entry
any sort of correction, as for instance for zero, for temperature, capillarity, ^c.
All these and the like corrections, being matter of calculation and reasoning
from other observations, are to be reserved till the final discussion of the se-
ries, and for separate determination and statement.*

5. If copies be taken of the registers, they should be carefully compared
with the originals by two persons, one reading aloud from the original and

• We regard this as of the liighe^t importance.

• Meteorological Observations. 139*

the other attending to the copy, and then exchanghig parts, a process always
advisable wherever great masses of figures are required to be correctly
copied.

.6. A copy so verified, or the original, (the latter being preferred) should be
transmitted regularly) if possible monthly from places within the limits of the
colony) to the Secretary of the South African Literary and Philosophical
Society, at Cape Town, which institution on its part will take care that such
documents shall not merely be treasured as a dead letter in its archives, but
shall be rendered available towards the improvement of Meteorological know-
ledge, to the full extent of their actual scientific value.

7. The register of every instrument should be kept in parts of its own
scale, as read off, no reduction of Foreign measures or degrees to British be-
ing made — but it should of course be stated wliat scale is used in each instru-
ment.

II. Of the Times of Observation and Registry.

Meteorological observations should be made and registered daily, at stated
and regular hours. In fixing on these, some sacrifice of system must of ne-
cessity be made to the convenience and habits of the observer. The best
hours in a scientific point of view would be those of Sun-rise, Noon, Sun-set,
and Midnight, and these are the hours for which the registers are kept at the
Royal Observatory. But these are not the hours adapted to general habits,
and since the midnight observation is likely to be pretty generally neglected
elsewhere than in an Astronomical Observatory, the following hours, for a
division of the day into three parts, are proposed for what may be deemed the
Morning, Afternoon, and Evening observations, viz.

Morning, . . . 8 a. M.
Afternoon, . . . 2 p. ai.
Evening, . . . 8 p. m.

If, however, the habits or engagements of any one should not allow him to
conform to these hours, rather than not observe he may select his own, spe-
cifying only what they are at the head of every page of his register, and ad-
hering steadily to them in practice, only observing to make the extreme ob-
servations of each day equidistant from the middle one.

At the same time it will be borne in mind, that in what concerns the great
Meteorological questions on which the most interesting features of the sub-
ject depend, the night is quite as important as the day, and has hitherto been
far too much neglected. To any one, therefore, who may feel disposed to en-
ter more zealously into the subject, and will not consider some personal in-
convenience ill undergone for the sake of affording data of a peculiarly valu-
able description, this Committee would most earnestly recommend the adop-
tion, in preference to all others, of the quaternary division of the 24 hours,
as followetl at the Royal Observatory above alluded to. And they leave it
to the consideration of the Council, whether the keeping and transmission of
registers on this principle might not advantageously be distinguished by some
honorary reward, as that of a Medal for instance, should the funds of the In-
stitution admit of it

With a view, however, to the better determining the laws of the diurnal
changes taking place in the atmosphere, and to the obtaining a knowledge of

140 Instructions Jar Making and Registering

the correspondence of its movements and affections over great regions of the
earth's surface, or even over the whole globe, the Committee have resolved
to recommend, that four days in each year should henceforward be especially
set apart by Meteorologists in every part of the world, and devoted to a most
scrupulous and accurate registry of the state of the Barometer and Thermo-
meter; the direction and force of the Wind; the quantity, character, and
distribution of Clouds; and every other particular of weather, throughout
the whole twenty-four hours of those days, and the adjoining six hours of the
days preceding and following.* The days they have been induced to fix on
and recommend for these observations are, the 21stof March, the 21st June,
the 21st September, and the 21st December, being those or immediately ad-
joining to those of the Equinoxes and Solstices, in which the Solar influence
is either stationary, or in a state of most rapid variation. But should any one
of those 2\st days fall on Sunday^ then it will be understood that the observations are
to be deferred till the next day^ the 22d. The observation at each station should
commence at 6 o'clock a. m. of the appointed da^'s, and terminate at G o'clock
P.M. of the days following, according to the usual reckoning of time at the
place. During this interval, the Barometer and Thermometer should be
read off, and registered hourly, and the precise hour and minute of each read-
ing should be especially noted.

For obvious reasons, however, the commencement of every hour should, if
practicable, be chosen, and every such series of observations should be accom-
panied by a notice of the means used to obtain the time, and, when practicable,
by some observation of an astronomical nature, by which the time can be in-
dependently ascertained within a minute or two.f As there is scarcely any
class of observations by which meteorology can be more extensively and es-
sentially promoted, it is hoped that not only at every station of importance
in this colony but over the whole world, and on board ships in every part of
the ocean, individuals will be found to co-operate in this inquiry. Every
communication of such observations addressed by channels as secure and as
little expensive as possible to the Secretary of this Institution, will be consi-
dered as highly valuable-
Ill. Of Meteorological Instruments^ and first of the Barometer and its
attached Thermometer.

The Barometer is the most important of all Meteorological instruments. Its
office is to measure the actual pressure of the atmosphere on a given hori-
zontal surface at the time and place of observation. Its fluctuations are ob-
served to have considerable relation to changes in the weather, and especially
of the wind. Hence its use as a weather-glass.

* This is necessary by reason of the want of coincidence of the day in different
parts of the globe, arising from difference of longitude. la order to obtain a complete
correspondence of observation for twenty-four successive hours over the whole globe,
it must be taken into account that opposite longitudes differ twelve hours in their
leckoninw of time. By the arrangement in the text the whole of the astronomical day
(from noon to noon) is embiaced in each series, and no observer is required to watch
two nights in succession.

•^ For example, the first appearances and last disappearances of the Sun's upper and
lower border, above and below the sea-horizon, if at sea or on the coast, — or on^land
the exact length of the shadow of a vertical object of determinate lengthen an horizon-
tal level, at a precise moment of time, (not too near noon}, &c.

Meteorological Observations. 141

A Barometer should be examined, before setting it up, for air-bubbles in
the tube, and for the existence of air above the mercury in the upper part of
the tube. This is done by gently inclining the instrument either way from
the horizontal position a little up and down ; when air-bubbles, if large, will
be seen to run to and fro, and must be evacuated by inverting the instrument
and by gentle blows on it with the hand, driving them up into the cistern.
If this cannot be done, the instrument is useless. If air exists to an objec-
tionable amount above the quicksilver, it will not tap sharp against the upper
end of the tube when the barometer is quickly inclined from a vertical
posilion, so as to make the mercury rise above its level, nearly to the top,
and then gently jerked lengthways and backwards. If the blow is puffy and
dead, or is not heard at all, the amount of air must be considerable, and may
be expelled by inversion.

In fixing the barometer, choose a good light near a window, but not exposed
to sunshine, in a retired apartment, little liable to sudden changes of temper-
ature or to drafts of wind. Adjust the tube to a vertical position by a plumb-
line, and fix it so as never to shift from that position. Before reading off,
give a few taps on the instrument, enough to make the upper end of the col-
umn of quicksilver shake visibly, as the mercury is apt to adhere to the glass
and give erroneous readings. In reading, bring the index always opposite to
one part. The correct part to choose is the summit of the convexity of the
mercury, to which the index should be made a tangent, but if this be difficult
to hit, either from the construction of the index or the want of a proper fall
of light, the line of junction of the mercury and glass may be taken. In that
case, the tapping should never be omitted. Whichever mode of reading is
once adopted should be stated, and always adhered to. A piece of white pa-
per placed behind the upper part of the tube will generally enable any one
to read off by the convexity of the quicksilver. In placing the index, notice
whether it appears to shift a little up and down as the eye is raised or de-
pressed ; this is called Parallax, and is a source of uncertainty to be avoided
by placing the eye in reading always on the exact level of the top of the mer-
curial column.

Barometric observations require corrections of three kinds, and to render
them available and comparable with others, it is necessary that their amount
should be ascertained, and distinctly stated. The first is called the Zero
Correction. It includes sev^eral subordinate corrections arising from differ-
ent sources, such as that originating in a faulty placing of the scale of inches,
that due to the capillary depression of the Mercury in the glass-tube, and the
constant part (which at a fixed station is nearly the whole) of the depression
arising from the presence of air or vapour in the upper part of the tube.

To determine the zero correction, the Barometer must be compared with
a standard instrument, such as that at the Royal Observatory for instance,
or some other which has been compared with it, or with some standard of
equal authority. Such comparison ought never to be omitted before for-
warding the Barometer to its place of destination, nor should any op{)ortu-
nity be neglected of comparing it, when fixed in its place, with a good por-
table Barometer. In making such comparisons, all that is necessary is to re-
cord the readings of both the instruments, after at least an hour's quiet ex-

Xjlfj Instructions Jor Making and Registering

posure, side by side, that they may have the same temperature. If compared
by two observers, each should read off" his own Barometer in his usual man-
ner, and each should take a mean of several readings, then each should verify
the other's results. By this means the zero of one standard may be trans-
ported over all the world, and that of all others compared with it ascertained.

The amount of the zero correction is often very large, as two or three-
tenths of an inch, but its influence on the mean results of recorded observa-
tions, falls wholly on the determination of the heights of the station of obser-
vation above the mean level of the sea, and effects little, if at all, any conclu-
sions of a meteorological nature which may be deduced from them. Hence,
if proper care be taken to preserve a Barometer, once set up, immoveable, a
long ^nd regular series of observation with it has a value independent of any
knowledge of this element, and it is fortunate that this is the case, as the
zero correction is one extremely difficult to determine exactly a priori.

In transporting a compared Barometer to its place of destination, great care
is necessary. It should always be carried upright, or considerably inclined,
and inverted, and over all rough roads should be carried in the hand, to break
the shocks to which it would otherwise be exposed. If strapped horizontally
under the roof of a colonial waggon, or tied upright' against the wood-work,
with its head resting on the floor, there is not a chance of its escaping de-
struction. Strapped obliquely across the shoulder of a horseman, however,
it travels securely and well, and with common care in this mode of transport,
its zero runs no risk of change.

Tbe next correction, and the most important of all, is that due to the tem-
perature of the IMercury in the Barometer tube at the time of observation.
To obtain this, every Barometer requires to have attached to, or fixed very
near it, a Thermometer, called the attached Thermometer, which must be
read and registered at each observation of the Barometer. It is preferable
in practice to read off this Thermometer jf?rs/, to avoid the error arising from
breathing on, or standing long near it, while reading the Barometer itself.
The zero of this Thermometer should be ascertained by comparison with a
standard at the temperature of about 60° Fahr.

The third correction applicable to barometric observations arises from
change of level of the mercurial surface in the cistern, owing to the transfer
of a portion of its contents to or from the tube. In Barometers with small
cisterns, and where the lower level cannot be adjusted at each observation,
its amount may be large, and its effect being always to make the apparent
fluctuation less than the real, in a Jlxed proportion, it ought, if possible, to be
ascertained. The data necessary to be known are — first, the internal and
external diameters of the tube — secondly, that of the cistern containing the
mercury, at the surface, where the tube plunges into it. These particulars,
as they must be known to the maker, ought to be inquired of him, and indeed
ought to be engraved conspicuously on some part of the instrument.

Although all these corrections are necessary for the strict reduction of re-
gistered observations, they ought not to be applied to individual observations
previous to registry. It is sufficient to know them. Their effect is in all
cases easily and safely applicable to mean results, and to the conclusions there-

Meteorological Observations. 1 43

from deduced, and a world of troublesome and often mistaken calculations
may be saved hy so applying them.

Of the External Thermomvier. — The External Thermometer should have a
scale on which whole degrees are read off, and divisions large enough to ad-
mit of estimating tenths, or at least quarters of degrees, by the eye. It should
be compared with a standard, and the difference stated, at one or more tem-
peratures (the wider asunder the better) within the range of the climate in
which it is to be used. In fixing it, choose a perfectly shaded but otherwise
free exposure, and one where no rejkcted sunbeams from water, buildings,
rocks, or dry soil, can reach it : and easily accessible for reading. There fix
it firmly and upright. In reading it, avoid touching, breathing on, or in any
way warming it, by near approach of the person. The quicker the reading
is done the better.

Although read off at stated times, notice should be taken of all sudden and
remarkable changes of temperature, as indicated by the external thermome-
ter, Avhenever they occur. In the neighbourhood of the Cape, and in many
other parts of the continent, hot winds frequently set in with great suddeiv.
ness, often in the night, and singular alternations of hot and cold temperature
occur, disturbing the regular laws of the diurnal fluctuation, and connected,
doubtless, with many interesting meteorological phenomena peculiar to the
climate of South Africa.

Of the Maximum and Minimum, or Self-registering Thermometer^^JIhis
should be placed horizontally in some place out of doors, shaded from direct
radiation and rain, and otherwise freely exposed to air, and so fastened as to
allow of one end being detached from the fastening and lifted up, so as to let
the indexes within the boxes slide down to the ends of the fluid columns, a
more convenient mode, when the steel index is free enough to allow it, than
the use of a magnet.

Both the thermometers should be read off as early as possible every morn-
ing, and the indexes re-adjusted. But as double maxima frequently, and oc-
casionally double minima occur, in consequence of sudden changes of tempe-
rature^ it is recommended occasionally to inspect both of them, with a view
to ascertain whether the motion of either the mercury or spirit has been re-
versed in an unusual manner, and such double maxima or minima, when re-
markable, should be recorded as " supemumerar}'," with their dates and lead-
ing features.*

The Self-registering Thermometer is extremely apt to get out of order, by
the indexes becoming entangled in the column of fluid. In travelling they
should not for a moment be carried with the mercury bulb downwards ; if
this should happen, they are sure to arrive in a state unfit for use. To cor-
rect them is tedious, and always hazards fracture. With great care, how-
ever, it may be done, as follows : —

lit. The Spirit Thermometer. By many jerks, force the index down to

• The spirit thermometer is apt to undergo a gradual change of sere by the transfer
(by distillation) of part of its spirit to the upper end of the tub*. It ihould, therefore,
often be compared with the mercurial one, and the diflfereoe* of Nadangs appUed m a
zero. In this only case is the apphcation of a xero htfore registering permissible, and
indeed essential.

144 Instructions for Making and Registering

the junction of the bulb and tube ; then, by cautiously hea/mg and cooling
alternately the bulb, the tube, or the air vessel at the top, as the case may
require, the disunited parts of the spirit may be distilled from place to place,
till the whole is collected in one column in union with the spirit in the bulb.

2rf, The Mercurial Thermometer. When the steel index gets immersed
in the mercury, it cannot be moved by a magnet, and lets the mercury pass
by its side. First cool the bulb (by evaporation of ether, if necessary) till
the mercury is either fairly drawn down below the index, or a separation
takes place in the column, leaving the index with mercury above it. Endea-
vour then, by tapping, warming the tube, or by the magnet, to loosen the in-
dex ever so little, then apply heat to the bulb, and drive up the index with
its superabundant mercury quite into the air-vessel. This requires many
trials and much patience. When there, hold the instrument bulb downwards,
and suspend the index by a magnet at the top, allowing any globule of mer-
cury to drop into the origin of the tube below ; then heat the bulb cautiously
over a very small clear flame of an oil lamp, till the mercury rises to the very
top of the tube, and fairly unites with the globule there awaiting it. Let the
bulb cool, and the mercury will sink in one united column ; if not, heat it
again. When this is accomplished, the index may be set loose, by withdraw-
ing the magnet, and restored to its proper position in the tube.

A self-registering thermometer may be advantageously left (properly se-
cured) for a whole year, or parts of a year, on elevated summits or other re-
markable points, to ascertain their maxima and minima of temperature du-
ring absence. In such cases, take care to defend them from discovery, or
acc! ^mt from wild animals, birds, snakes, &c. In taking it up for reading
off, observe not to derange the indexes, and do not leave it without seeing
that the indexes are in contact, and the temperature that of the air at the
moment.

Of Thermometers buried in the Earth. — Thermometers buried at different
depths, for the purpose of examining the monthly changes of temperature of
the soil, should have their balls and lower part of the scale well wrapped up
in woollen cloth or pounded charcoal, and should be placed in strong earthen
vessels, which may be entirely withdrawn from the ground so as to allow of
inspecting and reading off the scale, without exposing the balls to any possi-
bility of changing their temperatures while under examination. The vessels
should be fitted with covers, to defend the scale from injury in burying and
digging up.

A pipe of earthenware (composed of separate pieces), or one of wood, may
be sunk ten or fifteen feet below the surface, into dry earth, and a thermo-
meter, defended as above, lowered by a chain. The pipe being then ob-
structed at every two feet by some stuffing readily hooked up, the thermo-
meter may be easily examined, and a register of its indications kept with
very little trouble. In like manner, the temperature of wells may be regis-
tered.

0/the Temperature of the Sea The surface temperature of the water at sea

should be registered, as a matter of course, with the same regularity and at
the same hours as the barometer and thermometer. It is more conveniently
(and with quite accuracy enough for the purpose) obtained by taking up a

" Meteoroho^k al Observations. 145

hucketfull of the water and sUrring^ round the thermometer in it. When-
ever a change to the extent of 2° Fahr. appears to have taken place since the
last observation, a fresh hucketfull should be taken up and the observation
repeated. It should also be noticed whether rain has fallen since the last ob-
servation. A sudden depression of 3° or 4° indicates the near approach of
land. In a voyage from England, lately made by a member of this commit"
tee, the temperature of the surface water fell at once it" Fahr. on approaching
within a few miles of the entrance of Table Bay.

The temperature of the sea at considerable depths can hardly be regarded
as a subject of ordinary meteorological inquiry and regular registry, though
undoubtedly one of much physical interest, for which reason it is not consi-
dered necessary to dwell further on it.

-Of the Hygrometer^ ^c — In the absence of Daniell's Hygrometer, or of
ether to cool it, the degree of dryness of the air may be ascertained by ob-
serving the temperatures marked by two thermometers suspended freely side
by side (but not in contact) in the shade, and completely defended from all
radiation to or from the sky^ihe one having its bulb and stem naked, the other
with the bulb and lower part of the stem wrapped in linen or cotton, and
thoroughly wetted with pure spring or rain water. The temperatures indi-
cated by both should be noted when the wetted thermometer refuses to sink
lower, and the conclusions left for subsequent calculations. The naked ther-
mometer may be the " External Thermometer" itself, in which case a coated
thermometer may be kept always suspended near it, completely screened
as above mentioned, and wetted some minutes previous to the regular daily
readings.

If a hair hygrometer be used, its points of absolute moisture and dryness
should be frequently ascertained, as they are apt to change. The former may
be found by keeping it some time in a close covered jar lined with wet blot-i
ting paper, and having water in it, and noting the point of moisture beyond
which it refuses to go. The latter, by keeping it in the same manner in a jar
perfectly air-tight, over fresh burnt quicklime, till it refuses to indicate a
higher degree of dryness.

The best measure oi the momentary evaporating power oi the KXXt seems to be the
depression of the wetted thermometer below the dry one. But the actual eva-
poration from a given surface, is quite another thing, and a question may very
reasonably be raised, how far any useful approximation to a knowledge of the
total evaporation from an extensive and diversified surface, unequally moist-
ened, and variously exposed to the sun, defended by clouds, or refreshed by
dews, can be obtained by any small or local experiments.

The llain-gauge is an instrument of such extremely easy construction
that any person who lives near a tin-man can procure one. In a climate so
arid as that of Africa, however, it must be remembered that it will often need
examination and cleansing, owing to long intervals of disuse in which insects
and dust may lodge. It will often happen, too, that the slight rain of one
day, if left unregistered, will be entirely lost by evaporation in the next —
nay, that slight and transient showers may never enter it, being evaporated
from it as they fall. The effect of copious dew, too, must be separated from
that of rain, so that the mere registry of the contents of the gauge is not oC

VOL. XXI. NO. XLI. — JULY 1836. K

146 Instructions for Making and Registering

itself a sufficient indication whether rain has fallen in the night or not. How-
eyer, there are usually good reasons for decision on this point from other in-
dications. Attention to the amount of dew is very necessary, not only be-
cause the meteorological questions involved are of a high degree of interest
generally, but because in arid climates the dews are of almost as much im-
portance to the maintenance of vegetation as the rain.

In stating the quantity of rain daily received in the gauge, the height of
the receiver above the soil should be mentioned, experience having shown
that the quantities of rain which actually fall on a given area on the ground,
and at a very moderate height above it, often differ materially. In some
localities and circumstances, the rain-drops receive accession from the air as
they descend, in others they undergo partial evaporation. The former is ge-
nerally the case in cool moist climates — the latter may be expected in this
country.

Of the Wind. — The points most important to remark respecting the wind,
are,

\st, Its average intensity and general direction during the several portions
of the day devoted to observation and registry.

2dly, The hours of the day or night when it commences to blow from a
calm, or subsides into one from a breeze.

3rf/y, The hours at which any remarkable changes of its direction take place.

Athly, The course which it takes in veering, and the quarter in which it
ultimately settles.

bthly., The usual course of periodical winds, or such as remarkably prevail
during certain seasons, with the law of their diurnal progress both as to di-
rection and intensity — at what hours and by what degrees they commence,
attain their maximum, and subside, and through what points of the compass
they run in so doing.

Sthly^ The existence of Crossing Currents at different heights in the atmo-
sphere, as indicated by the course of the clouds in different strata. In observ-
ing these, it is advisable to fix the eye by some immoveable object, as some
point of a tree or building, the sun, or the moon, other«vise mistakes are apt
to arise.

Tthlt/j The times of setting-in of remarkably hot or cold winds, — the quar-
ters from which they come, and their courses, as connected with the progres-
sive changes in their temperature.

8thlp, The connexion of rainy, cloudy, or fair weather, with the quarter
from which the wind blows or has blown, for some time previous.

9thly, The usual character of the winds as to moisture on dryness, not as
deduced from mere opinion or vague estimation, but from actual observation
of the hygrometric state of the atmosphere during their prevalence.

Among these particulars it will be seen that some are of a nature suscepti-
ble of daily observation and registry, while others call for an exercise of the
combining and inductive faculty on the observer's part, and cannot be made
out otherwise than by continued attention and habitual notice of phenomena
with a view to the investigation of their laws. The general impression left
upon the mind as to any of the points of this kind above enumerated, by the
occurrences of the past month, will therefore be more properly stated, in tlie
way of summary remarks at the end of the Monthly Registers, than as en-
tries under particular days.

Meteorological Observations. 147

Of the State of lhe\Sky — In describing the state of the sky as to clouds, Ac.
the observer will bear in mind that it is only in that region of the sky which
is vertically above him that the true forms and outlines of the clouds are
exhibited, and the area they cover, as well as the intervals between them dis-
tinctly seen. As they approach the horizon in any direction, their extent is
foreshortened by perspective, their apparent magnitude diminished by dis-
tance, and their intervals covered in and hidden by their mutual interposition.
In estimating therefore the quantity of clouds in the sky, regard must be had
to this, and our judgment should rather be formed on a view of the region
extending from the zenith every way half way down to the horizon, that
from the aspect of the heavens below that limit. It would be better to no-
tice both, and state, separately, the proportions in which each are covered,
and the quarter of the horizon towards which the chief masses in the lower
region lie.

The general aspect of Clouds, as classed under the heads Cumulus, Cirrus,
Stratus, &c. should be noticed, and especially the height of this inferior sur-
face, or the level of the vapm$r plane, should be estimated. In a mountain-
ous region this is easy, so long as the vapour plane is below or not far above
the summits of the hills, and in such regions the formation and dissipation
of cloud in the nei^rhbourhood of the mountain summits, under the influence
of certain winds, form a subject of study of a highly curious and interesting
nature.

The formation of Clouds at night, during calm weather, under the influence
of a gradually descending temperature, is another point worthy of attention.
It frequently happens, that, without any perceptible wind, the sky will sud-
denly become hazy in some one point, and the haze condensing and spreading,
in all directions, without a wind, the whole heaven will become overcast in
a remarkabl}-^ short time. The same thing will sometimes occur nearly at
the same hour for many nights in succession. Such phenomena should be
noted whenever they occur.

Two or even three strata of clouds are very common in this district of
South Africa. The lowest frequently resting immediately on the land and
sea. The height and thickness of these strata, their connexion with cross or
opposite currents of wind in the regions wliere they subsist, and the laws of
their formation in gradual intermixture, deserve to be studied with care, aod
with reference to the hygrometic state of the air at the time and place, and
for several hours before and after.

Of Thunder and Lightmng, and qf the Electrical state of the Air. — Connected
with this part of the subject is the observation of shooting Stars and lumi-
nous Meteors. Remarkable ones should be noticed, and the moment of their
appearance, their direction, duration, length of path, and course among the
Stars, ascertained and noted, with the phenomena of their increase and decay
of light, apparent size, separation into parts, trains left behind, &c. The^
neral direction (if any) which they observe on particular nights, is a point also
to be attended to. Such are the frequency and brilliancy of these splendid
phenomena in the clear sky of this colony, that there can be no doubt of their
affording an available method of ascertaining the differences of longitude of

k2

148 Instructions Jbr Making and Registering

the most distant stations, if duly OLVserved by persons furnished with means
of ascertaining the time.

Thunder-storms of course will be noticed when they occur under the gene-
ral head of the weather, but it is of consequence also to notice distant light-
ning, not accompanied with thunder audible at the place of observation (by
reason of its great distance), * especially if it takes j)lace many days in suc-
cession, and to note the quarter of the horizon where it appears, and the
extent it embraces. In an actual thunder-storm, especial notice should be
taken of the quantity of rain that falls, and of the fits or intermittances of
its fall, as corresponding, or not, to great bursts of lightning, as also of
the direction of the wind and the apparent progress of the storm with or
against it.

Observations of the Electrical state of the Air in serene weather are un-
fortunately too much neglected. The apparatus they require is simple, and
by no means costly, and may be constructed indeed by any one for himself
with ease.

If the Committee in this their first Report do not dilate on this and other
of the less usually practised observations of Meteorology, it is because they
wish for the present chiefly to call attention to the accumulation of re-
gular and daily observations of a more definite and numerical character. With
this view they have drawn up, and by the liberal aid of Government, have
procured to be printed skeleton forms, of which a copy is annexed, for im-
mediate distribution among such Correspondents of the Institution, and others,
as may be willing to undertake their filling up. These comprise, it is true,
only the registers of the Barometer and its attached Thermometer, with
that of the external Thermometer, and a column of Remarks for Wind and
Weather, as being the most essential and indispensable elements of Meteoro-
logy ; but it is in the power of any one who pleases to supply additional infor-
mation, and to those who have leisure, instruments, and inclination for the
task, the Committee would particularly recommend the regular observation of
the Wet Thermometer, those of the SeU-registering Thermometer and Weekly
or Monthly Observations of Thermometers buried at different and progressive
depths beneath the surface of the soil.

The printed forms provide for the arithmetical convenience of casting up
the means for each month. In doing so, it is requested that care will be taken
to verify the results by repetition, and (that usual sources of error may not
escape notice) they recommend in every instance, before adding up the
columns, to look down each to see that no obvious error of entry (as of an
inch in the barometer, a very common error, or what is more difficult of de-
tection, an error in the first decimal place) shall remain to vitiate the mean
result. It is perhaps unnecessary to do more than mention the precaution of
counting the days in each column on which observations occur, so as to admit
of no mistake in the divisor^ and to use throughout the decimal arithmetic in
calculating the mean ^results. Care and exactness in these points will in

* Thunder can scarcely ever be heard more than 20 or 30 miles from the flash
which produces it. Lightning, on the other hand, may be seen (or at least its re-
flexion on the clouds, forming what is called sheet lightnimf) at the distance of 150 or
200 miles.

Meteorological Observations. 149

most cases add greatly to the value of the communications, as it will be quite
impracticable for the Committee, should observations flow in in masses, unre
duced or erroneously reduced, to undertake the overwhelming task of recom.
puting them.

Although not, strictly sj)eaking, a branch of meteorology, yet as the col-
lection of observations of the Tides has been made a part of the duties of your
Committee, they propose the following stations as points where it would be
esj)ecially desirable to obtain regular observations of the time and height of
high and low water, according to the rules and on the plan proposed by
Mr Whewell, in his late researches on this subject, and they earnestly invite
communications on this head from any residents at those ports who may have
leisure and take interest enough in the important questions connected with
the subject.

Cape Town, Ascension,

Simon's Bay, Mauritius,

Port Elizabetli, Tristan d'Acunha,

Knysna, Madagascar,

Saldanha Bay, Mozambique.

In Cape Town and Simon's Bay, they have the pleasure to report, that a
series of observations under the superintendence of Captain Bance and Mr
Levien have already been undertaken at the instance of the Astronomer-Royal,
and are now in active progress.

Oti a Method of Drilling, Turning, and Working Glass, by
means of Turpentine. By Mr John A die.*

68 Prince's Street, Edinburgh,
Dear Sir, mh February 1836.

Agreeably to your request, I shall here state the method
of drilling or turning glass, which I had the honour of com-
municating to the Society of Arts last Session.

It consists simply in using oil of turpentine with the com-
mon drill, file, or turning tool ; and if care be taken that the
cutting edge is never dry, it will not soon blunt, and the glass
will be worked with great expedition.

I learned this curious fact when in London last spring, and
that it was by accident discovered by a Frenchman. I am,
dear Sir, yours, &c. (Signed) John Adie.

To the Secretary of the
Society of Arts for Scotland.

• Read before the Society of Arts for Scotland, 11 th March 1833.

( 150 )

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( 152 )

General Table of Meteorological Observations

at Fort Vancouver, from

General Annual
Means.

June.

July.

August.

September.

October.

Barometer,
English inches,
reduced to 32°
F.

9 A. M. 30.043
Noon, 30.035
3 P. M. 29.985
9 p. M. 30.041

Max. 30.624
Min. 28.994
Range, 1.630

30.035
29.999
29.953
30.006

30.337

29.665
0.672

30.070
30.020
29.990
30.008

30.215

29.798

0.417

30.005
29.953
29.899
29.957

30.301

29.689

0.612

30.049
30.024
29.968
30.011

30.320

29.623

0.697

30.026
30.013
29.955
30.014

30.431

28.994

1.437

Thermometer
of Fahrenheit
corrected for
ind. error by
standard oi
Royal Soc. L.

7-8 A. M. 45°.8
Noon, 58.4
3 p.m. 59.1
Sunset, 54,8

Max. 92
Min. 18
Range, 74

56°. 8
72.1
74.0
66.5

92

48
44

59°.6
76.8
80.6
72.8

92
54
38

56°.6
73.6
75.4
68.9

86
49
37

53°.9
69.6
70.2
63.5

86
46
40

46°.2
57.4
68.9
55.3

73
36
37

Daily Range of
Thermometer,

Max. 33°
Min. 2
Mean, 14.5

32°

8

17.5

31°

9

21.4

27°

7

19.4

32°

2

17.1

33°

5

15.9

Days of Rain,

on which any
Rain fell.

157

4, 5, 6, 7,
9,110,11,
12,20=9

5, 19, 22,
23 = 4

14,15,17,
25 = 4

14,15,17,
18,27,28,
29 = 7

1, 4th —
7th, 9, 10,
15,24,26th
— 31 = 15

Depth of Rain
in English in.

53.646

0.880

0.118

0.407

2.040

7.540

Days on which
any Snow fell.

1

Depth of Snow
in Engl, feet,

0.08

Prevailing
Winds,

No. of Obser-
vations,

N. 26 S. 149
NE. 14 SW. 178
E. 101 W. 31
SE.136 NW. 81

Calm 159 Tot. 885

13

46
2 3
4 4

16 88

10 8
1 34

3

1 21

20 86

8 17
28
9
2 9

14 94

7 11
4 17
2 8

10 13

11 83

13
19
5 2
16 13

20 88

Days of Frost,
Ther. observed
below 32° F.

34

Days of Hail,

4

Days of Thun-
der,

. 2

1,20 = 2

Evaporation of
water in En-
glish inches
in 24 hours,

Max. 0.90
Min. 0.00
Mean, 0.18

No. Obs. 188
Total, . .

0.70
0.15
0.29

18

0.90
0.15
0.48

26

0.50
0.10
0.28

22
8.60

0.45
0.04
0.28

23
5.23

0.29
0.06
0.14

14

2.77

Dew-point at J
Noon, 1

Diff. between (
dew-pt. and-|
temp, of air, (

No. of Obs.

Max. 56
Min. 23
Mean, .

Max. 24
Min. 1
Mean, .

147

No obs.

No obs.

No obs.

No obs.

56°
38
47

23

5

12

29

N. B. — The depth of Rain is ascertained by weighing the water at end of every month, re- ,
ceived into a close bottle, by a funnel of known diameter, and calculating from thence J
the depth in inches by Dalton's formula in his Meteorological Essays. %

Evaporation is measured by immersing a graduated style into a pewter basin five inches in
diameter exposed freely to the air.

( 153 )

June 1. ISS^ to May 13. 1835. Communicated by Dr ?♦!. Gairdnsr.

November.

December.

January.

February,

March.

April

May.

29.972
2.9.968

2!).!>45
2!). 970

30.263

29.287

0.976

4r.9
50.9
4.9.2
48.9

61
31
30
22°
5
11.3

30.122
30.122
30.057
30.123

30.611
29.241

1.370

33°.8

41.0

40.9

37.8

5

18

32

20»
3
9.7

29.874
29.8.59
29.850
29.871

30.454
29.465
0.989
38°.6
44.7
45.0
43.0

56
29
27

30.125
30.118
30.077
30.108

30.521

29.555

0.966

30.135
30.149
30.124
30.168

30.624

29.498

1.126

30.167 15 obs.
30.193 18 obs.
30.095 15 obs.
30.218 Sobs.

30.476

29.806

0.67a

29.936 12 obs.
30.000 10 obs.
29.909 Sobs.

30.336

29.596

0.740

37°.4
47.4
47.2
42.5

58
28
30

39°.0
51.6
52.2
46.3

64
31
33

40°.4 7 obs.
57.9 13 obs.
62.7 11 obs.
56.4 14 obs.

73

34

39

63°.6 Bobs.
56.1 12 obs.

8.2

26°
3
11.3

20°

5

12.8

29°
5

No obs.

1st — 5th,
8th, 11th _
21st,27th—
30th = 21

1st — 8th,
21, 25th —
31 = 16

Ist — 16th,
18th— 2l8t,
23d— 29th
= 26

1 0th _ 14th,
M 5th —24th,
27, 28-= 8

1 — 7, 8 —
10,16,18,19,
20, 22 — 31
= 21

3, 7th _ 10th,
15th — 17th
= 8

2, nth — 16th,
19, 21, 26, 27

4.550

9.846

10.646

6.654

QMb

2.000

2.000

25 = 1

0.08

»

13

2 4

14 2

25 4

17 81

1 12

I

21

28

19 82

11

3

20 1

27 5

17 84

3 11
1 11

22 3
14 7

12 84

2 37

5 4

10

9 4

20 91

3

1 11
5
1

3 24

[No obs.

25,26 = 2

10 _ 24th
= 15

14, 17, 18,
22, 30, 31,
= 6

4th — 9th,
25,26=8

5,11,17 =
3

8,23,29 = 3

11 = 1

0.25
0.03
0.11

8
1.50

*

0.07
0.06
0.06

2
1.81

0.13
0.00
0.06

26
1.74

0.27
0.00
0.09

24
2.12

0.22
0.07
0.11

21
3.08

0.26
0.07

4

No obs.

50°

35

43

13

1
7

27

44°

28

37

14

6

15

49°
36
42

7
1
4

24

52
23
39

21

4

10

24

44°
32
39

21

4

11

24

41°
36

24
15

4

No obs.

Dew-point is ascertained by means of an instrument on the principle ot Pouillet's, but using
a thin transparent glass capsule, which, upon trial, 1 have found more delicate than a po-
lished metallic surface.

Fort Vancouver is about 60 feet above the level of the sea.

/ ( 354 )

Description of' several New or Rare Plants ivhich have latcltj
Flowered in the Neighbourhood of Edinburgh , chief lij in the
Royal Botanic Garden. By Dr Graham, Prof, of Botany.

June 10. 1836.
Acacia lincata.

A. lineata ; stipulis subnullis ; phyllodiis lineari-spathulatis, subfalcatis,
versus marginem superiorem uninervibus, oblique cartilagineo-miuro-
uulatis, ramuloque rotundato pubescentibus ; capitulis longe peduncu-
latis, subgeminis.

Acacia lineata, Cunningham, in Don's Syst. of Gard. 2. 403. n. 28 — Bot.
Mag. 3346.

Description. — Shrub slender; branches diftuse, round, rough, tuberded
by the persistent hardened bases of the phyllodia ; young shoots densely
pubescent, pubescence spreading or slightly reflexed, somewhat viscid.
Phyllodia linear-spathulate, slightly falcate downwards, pubescent in ra-
ther a smaller degree than the young branches, marked by an obscure
sessile gland on their upper edge near the base, terminated obliquely by a
small blunt somewhat hooked callosity, single-nerved, the nerve being to-
wards the upper edge, and slightly, but not always evidently branching,
upon its lower side. Peduncles twice as long as the phyllodia, single or ge-
minate, supporting single capitula of orange-yellow perfumed polygamous
Jlowers, each of which rises from the axil of a concave, rounded, ciliated,
nearly colourless bractea. Calyx segments 5, minute, linear, ciliated.
Corolla 5-petalled, petals ovate, acute, clawed, spreading, twice as long as
the calyx. Stamens very numerous, twice as long as the corolla. Ger-
men oblong, pale green. Style oblique, longer than the stamens.

We received this plant from Kew, and it flowered in the greenhouse of the
Botanic Garden in February 1836.

Begonia Fischeri.

B. Fischeri ; caulescens, foliis oblongis, acutis, insequaliter cordatis, den-
tate- serratis, utrinque glabris, nitidis; stipulis ovatis, integerrimis ;
floribus masculis 4-petalis, petalis exterioribus rotundis, concavis, mar-
ginibus plano-revolutis ; floribus foemineis 6-petalis, petalis ovato-lan-
ceolatis, alis germinis inaequaliter rotundatis.

Begonia Fischeri, Otto, MS.

Descriptiok. — Stem erect, branched, fleshy, swollen at the joints, red,
shining. Leaves unequally cordate, acute, indistinctly sinuated, slightly
undulate, unequally dentato-serrate, glabrous on both sides, when y«>ung
bright red behind, paler at the veins, and pink above, with a peculiar
silvery lustre, which continues in the old leaves, the colour being then
beautifully delicate yellowish-green, and the redness behind much less
considerable ; petioles nearly round, half as long as the leaves. Stipules
large, ovate, acute, entire. Peduncles axillary, twice as long as the pe-
tioles. Cyme twice or oftener forked, branches divaricated. Male flowers
in the forks of the cymes, 4-petalous, the outer petals rounded, with a si-
nuosity on one side, where the pedicel is attached, hollow in the centre,
with flattened somewhat revolute edges, forming a perfect miniature of
abarber's bason; inner petals obovato-cuneate, undulate. Stamens united
only at their insertion. Female flowers 6 petalous, the petals ovato-lan-
ceolate. Germen rather unequally winged, the wings unequally round-
ed.

This plant, which has small flowers, but exquisitely beautiful foliage, was
received at the Botanic Garden from Berlhi, under the name adopted, in
1835, and flowered in the stove in February and March 1836.

Dr Graliaurs List of' Rare Plants. 156

Hegonia sanguinea.

B. sanguinea ; caule raniusu ; foliis ina;qualiter cordatis, acumiiiatis, co-
riaceo-carnosis, glaberriniis, subtus sanguineis, margine crenulato re-
voluto ; germinis alis tribus aequalibus.
Begonia sanguinea, Radd. in Spreng. Syst. Veget. 2. 625 — Link and Otto,
Icones Plant. Karior. Hort. Reg. Bot. Berol. p. 25, t. 13.

Descriptiok Stems several from the crown of the root, subligneous, red

with scattered oblong paler spots. Leaves (4-6 inches long, 24-3^ inches
broad) subpeltate, unequally cordate, acuminate, the apex soon wither-
ing, leathery-succulent, perfectly glabrous and shining on both sides,
green above, blood-red below, the edge crenulate and revolute all round ;
nerves about 10, radiating, the larger branched, the smaller subsimple.
Petioles of very unequal length, round, resembling the stem. Stipules
intrafoliaceous, large, ovate, acute, keeled, marcescent. Peduncle (10
inches long) terminal, becoming axillary, tapered, similar to the stem,
but without spots, repeatedly dichotomous at the apex (primary branches
about one inch long, the others gradually shorter). Bructece lanceolato-
elliptical at each subdivision. Flowers white, rather small. Male Jiowers
in the clefts of the cyme, or on the inner side, when the ultimate
branches are reduced to two flowers, the outer being a female ; petals
four, the two oucer subrotund, slightly crenate, the two inner linear-el-
liptical, very narrow, entire ; stamens numerous, filaments free, except-
ing at the base, where monadelphous, anthers spathulate. Female Jiowers
with five subequal petals., expanding later than the earlier of the males ;
stigmas pale rose-coloured ; germen with three subequal wings.
I was at some i)ains to ascertain the relative position of the male and fe-
male flowers, when only these two were found at the extremity of the
ultimate branch. It seems to me that the normal form is the conversion
of the last dichotomous ramification of the cyme into the pedicels of two
female flowers, and that the male flower, here, as elsewhere, is placed in
the cleft, the loss of the inner female flower being an illustration of the
opinion that internal parts, from pressure, more frequently abort than
those which are external. As the common support of these two flowers
generally turns half-round on its axis, their true position may not be ob-
vious, unless examined when they are very young.
This plant, more remarkable for the colour and texture of its leaves than
elegant in its form, was raised at the Botanic Garden, Berlin, from seed
transmitted by Sello from Brazil in 1823, and communicated to the Bo-
tanic Garden, Edinburgh, in 1832. It flowers in the stove in April.

Bletia patula.

B.patula; foliis radicalibus, lanceolatis, jilicato-nervosis ; scape elate,
subramoso ; floribus patentissimis ; sepalis lanceolato-ellipticis, basi at-
tenuatis, subaequalibus, patulis ; labello cucuUato, lobis lateralibus ro-
tundatis, intermedio emarginato transverse plicate, disco lamellis 6,
subramosis, injEqualibus.

Description Bulb round, at first, when it pushes up the scape, very

small, gradually enlarging to the size of a small orange ; in the second
year green, shining, nearly smooth, and crowned by the withered bases,
of the leaves, when these fall, marked with three or four circular bands,
and furrowed at the apex, persisting for some years, and becoming gra-
dually smaller without shrinking much ; young bulbs are formed at the base,
or near the apex of those of the year preceding. Leaves arising from
the apex of the bulb after the flowers, lanceolate, plicato-nervose. Scape
(above 3 feet high) purplish and spotted at the base, with a few distant
sheathing scales, greener above, subrameus, terminal, but from its appear-
ing in the very young state of the bulb seeming to be lateral, the old bulb
only being conspicuous. Raceme (above 20.flewered) gradually elon-
gating. Flowers large, very handsome, each springing from the axil of a

156 Dr Graliam'*s L'lst of' Rare Plants.

small acute bractea, of nearly uniform reddish-lilac colour, only the base
of the lip and its ridges being white. Sepals (1^ inch long) lanceolato.
elliptical, nearly equal in size, the uppermost being rather the narrowest,
all attenuated at the base, and spreading. Lip without spur, much
broader than the sepals, the lateral lobes erect, the central broad-linear,
notched, plaited transversely ; disk with six waved, somewhat branched
lamellie, those nearest the sides being the shortest, and passing into di-
verging veins. Column more than half as long as the sepals, projecting
into the centre of the flower, somewhat clavate, rounded on the upper,
flat on the lower side, with a single tooth on each edge at its middle, a
small terminal tooth, and two others on each edge immediately below
the apex, the lower being rounded and decurrent. Anther-case rounded,
emarginate, 2-celled, each cell divided longitudinally. Pollen-masses 4,
parallel, each 2.1obed, laid along a thin plate, which is spread above the
moist stigmatic surface. Germen (14 inch long) twisted, spreading at
right angles to the rachis.
This handsome species was received at the Botanic Garden from Dr Fischer,
St Petersburgh, in 1830, without specific name, but marked as a native
of HaytL It has repeatedly since flowered freely in our stove, imme-
diately succeeding Bletia verecunda in the end of Maicb.

-Drosera filiform is.

D. filiformis ; scapis lateralibus, foliis lineari-filiformibus glanduloso-pi-
losis, dorso glabris canaliculatis, basi lanatis ; staminibus 5 ; stylis 8,
in paribus coalitis, basi.
Drosera filiformis, Rafinesque., in Need. Rep. 2. 360 — Ibid, in Besv. Journ.

de Bot. 1. 227 Pursh, Fl. Amer. Sept. 1. 211 A''m^;. Gen. 1. 142

Roem. et Schult. Syst. Veget. 6. 763 — De Cand. Prodr. 1. 31 8. ^Torr^y,

Fl. of North, and Mid. Sect, of United States, 1. 332 Smeng. Syst.

Veget. 1. 955 — Bech, Bot. of North and Mid. States, p. 42.

Drosera tenuifolia, Willd. Enumer. p. 340 — Roem. et Schult. 1. 763

Bigelow, Plants of Boston, p. 124.
Description — Primordial leaves deltoideo- subulate, glabrous ; secondary
leaves radical, linear, circinate, very woolly at their base, channelled and
glabrous behind, in front rounded and covered with spreading greenish
hairs, which support on their summit a. red gland, and exude a viscid
colourless juice. Scape lateral, with us always simple, green, glabrous,
about as long as the leaves. Spike racemose, unilateral. Pedicels and 5-
cleft persisting calyx covered with green glandular hairs. Corol'a gla-
brous, rose-coloured, more than twice as long as the calyx, marcescent;
petals 5, obovate, claws greenish. Stamens 5, scarcely longer than the
calyx ; filaments colourless ; anthers erect, oblong, yellow ; pollen gra-
nules round, yellow. Styles 8, spreading at their base in pairs, above
erect and clavate, colourless. Germen round, green, ovules numerous,
oblong.
This remarkable species was found by Mr James Macnab in a swamp about
ten miles above Tuckerton, New .Jersey, U. S., and introduced by him
into the gardens about Edinburgh in 1834. It flowered freely in the
stove at Dr Neiirs,at Comely Bank Nursery, and with us. I cannot he-
sitate to agree with those who consider Drosera tenuifolia of Willd., sy-
nonymous with Z>.^7«/brfwwof Rafinesque, which, being the earliesi pub-
lished name, I retain.

Epacris microphylla.

E. microphylla''; calycis foliolis obtusiusculis, tubum corolla? nequantibus ;

foliis cordatis,acutis,pedunculum superantibus, lateribus erectis; spica

apiciflora; ramulis pilosis.
Epacris microphylla, Br. Prodr. Fijr. Nov. Holland. 650.

Description ^'S'^*'"^ erect ; branches ascending, slender, tortuous, hairj'

Leaves cordate, spreading, shining, rigid, sides folded forwards, base em-

Dr Graham's Lut of Rare Plants. 157

bracing the stem, middle bent tack, apex ascending, acute. Flowers
white, solitary in the axils of the leaves, collected into subterminal
pseudo-spikes, on peduncles shorter than the leaves. Calyx leufets oblong,
blunt, white. Corolla white; tube campanulate, equal to the calyx,
nectariferous ; limb 5-parted, segments ovate, blunt, spreading. Sta-
mens alternating with the segments of the corolla ; filaments adhering
to the tube, the free portion erect, shorter than the limb ; anthers bi-
locular, bursting along the face. Germen spheroid, with a short style
rising from the depressed apex, and supporting a stigma of five erect
blunt lobes.

We received this plant at the Botanic Garden, Edinburgh, in 1035, from
Mr Westland's nursery, near Dorking, Surrey, where a large stock of
scarce plants, and of EpacridcB in particular, are cultivated with a very
remarkable degree of success. It tlowered in the greenhouse during the
month of March.

Mr Brown places this species next to E. pulchella, and, were it not for his
authority, I should certainly have considered it only a variety of this. I
do not find the difference in the form of the calyx segments, nor of the
leaves, which Mr Brown observes, and would rest the chief distinction
on the more slender, less tortuous branches of £. microphylla, the hairi-
ness of the young shoots, the shortness of the peduncles in relation to
the leaves, and in the pseudo-spikes being collected nearer the extremi-
ties of the branches.

Fritillaria ruthenica.

F. ruthenica ; caule subunifloro ; foliis lineari-lanceolatis, imis superiori-
busque subtematis, illis obtusis, his, intermediisque^ sparsis, cirrhosis ;
floribus tesselatis cernuis.
Fritillaria ruthenica, Wickstrom f
Corona verticillata, Fischer. MS.

Description — Stem slender. Leaves linear-lanceolate, glaucous, chan-
nelled above, 3-6-nerved below, upper ones erect, the others spreading,
lowest and uppermost subternate, those which intervene scattered at
distances gradually increasing upwards, all terminated by cirrhi, except-
ing those composing the lowest verticel, which are more or less blunt.
Flowers cernuous, in the specimen described two, the one terminal,
springing from the centre of three leaves, the other a little below the
apex, ana subtended by two leaves, which are in contact on one side of the
stem. Peduncles (half an inch long) resembling the stem. Perianth cam •
panulate, tesselated, dark purple on the outside, somewhat paler within,
segments terminated with a small tuft of minute hairs, and having along
the centre of the inside of each a linear green mark, which leads to a
subrotund nectary near the base, corresponding to a large gibbosity with-
out, inner segments obovate, outer elliptical and narrower. Stamens half
the length of the perianth; filaments filiform, very slender; anthers
erect, equal in length to the filaments, yellow, elliptical ; pollen granules
yellow, minute, subglobular. Pistil longer than the stamens, but shorter
than the perianth; germen green, 3-sided, slightly contracted at its ori-
gin ; style green, about as long as the germen, trifid, with internal deeply
grooved stigmatic surfaces.

This neat little species of Frilillaria was received by Dr Neill under
the name here adopted, from the Botanic Garden, Berlin, in August
1835, and flowered in his greenhouse at Canonniills, near Edinburgh, in
the following April. No doubt it will thrive in the open air as well as
any of the species.

I refer to Wickstrom with doubt, because 1 have not an opportunity of
consulting his original observations, and the definitions of the species by
authors who quote him, scarcely apply to the plant before me. The MS.
name of Fisclier is attached to a specimen in my herbarium from the
south of the Volga, which he with his usual kindness sent to me. It

158 Proceedings of the Royal Society of Edinburgh.

differs in no essential degree which I can perceive from Dr Neill's plant,
and is not the Fritillai-ia verticillata of Ledebour, which is Fritillaria leu-
cantha of Bot. Mag. 3083, which I have from Dr Fischer under the
names of Imperialis leticantha and Corona leucantha.

Proceedinjys of the Royal Society of Edinburgh.

1836, February 1. — Sir Thomas M. Brisbane, President,
in the Chair. The following Communications were read :

1. On the Mathematical Form of the Gothic Pendant. By
Professor Forbes. Published in the Annals of Philosophy.

S. On the occurrence of the Megaliciithys Hibberti in a bed
of Cannel Coal in the west of Fifeshire ; with Observa-
tions on the supposed Lacustrine Limestone of Burdie-
house. By Leonard Horner, Esq. F.R.SS. L. h E., and
F. G. S. PubHshed in the last Number of this Journal.

February 15 — Dr Hope, V. P. in the Chair.

The Keith Prize delivered to Professor Forbes, on which oc-
casion, an address was delivered by Dr Hope, which appeared
in last number of this Journal.

March 7. — Sir T. Makdougall Brisbane, President, in
the Chair. The following Papers were read ;

1. On the Non-Hellenic portion of the Latin Language. By
the Venerable Archdeacon Williams.

The line of argument went to shew, that the Umbri were
one of the most ancient nations of Italy. That they, through
their colonies, entered deeply into the composition of the primi-
tive population of Rome. That, according to ancient authorities,
these Umbri were the descendants of the " Veteres Galli." That
these Veteres Galli were of the same race and blood as the present
Cumbri of Wales, Cornwall, and Brittany. That hence it is pro-
bable, that the ancient language still preserved among these may
have entered early into the composition of the language of the Ro-
mans. That the names of rivers, mountains, cities, lakes, districts,
&c. in central Italy, and in all the countries over which the Sabel-
lian tribes, and their cognate race the Veneti, diffused themselves,
is likely to convert this probability into certainty. That the ques-
tion concerning the ancient population of Italy has never yet been

Proceedings of the Royal Society of Edinburgh. 159

satisfactorily treated ; that it never can be, unless the examiner is
well acquainted not only with the language, but also the literature
of Greece and Rome, and with at least one type or form of the se-
veral Teutonic and Celtic languages. That a slight acquaintance
with other forms is also very desirable. That the writer professes
to be conversant with Greek, Roman, and Cumbrian literature, and
to a certain extent with the Anglo-Saxon, and that he knows some-
thing of the Gaelic and Basque tongues. That no examination of
indexes can avail, owing to the peculiar character of the Cumbrian
tongue, in which a person ignorant of the principles of its grammar
might suspect that there was nothing fixed, while, on the contrary,
it is the most fixed and indestructible of all languages. That the
vocabularies of the Latin and Cumbrian languages are strikingly si-
milar, although their grammars are radically different. That the
work of comparing the two languages etymologically would be
easy, had it not been for the long stay of the Romans in Gaul and
Britain, which must be supposed to have made a deep impression
upon the language of the natives. That nevertheless many Latin
words exist, to the primary meaning of which the Cumbrian scho-
lar alone possesses the key, and that a long list of words belonging
to such a class must prove that some cognate branch of his language
must have entered into the original composition of the Latin tongue.
That the strength of the proof must depend upon the extent of the
induction.

2. On the Sources and Composition of the difl^trent kinds of
Gamboge. By Dr Christison. 3. On the Botamcal
Origin of Gamboge. By Dr Graham.

Gamboge was first made known by Clusius about the commence-
ment of the seventeenth century, as a concrete juice from China.
About the middle of the same century, Bontius conceived he had
traced it to a particular species of Euphorbia^ growing in Java and
in Siam ; from the latter of which countries the whole gamboge of
commerce was at that time obtained. About the close of that cen-
tury Hermann announced that gamboge was produced by two spe-
cies of trees growing in Ceylon, which have been since often con-
founded together, but which are now designated by the names
Garcinia Gambogia, and Stalagmitis Gamhogioides. About the mid-
dle of last century, gamboge was referred by Linnaeus to the for-
mer of these plants, and his reference was generally admitted.
But about thirty years later. Professor Murray of Gottingen con-
ceived he had trace<l it satisfactorily from the specimens collected
by Koenig in Ceylon, and information obtained by the same bo-
tanist in Siam, to a new species which he called Stalagmitis garri'
hogioides.

Dr Graham shows, from specimens and drawings sent from Cey-
lon, both by Mrs Colonel Walker to himself, and by David Ander-
son Blair, Esq. to the late Dr Duncan, that the plant producing
Ceylon gamboge is neither Garcinia gambogia^ as Linnseus thought,

160 Proceedings of the Royal Society.

nor Xanthochymus ovalijolius, as conjectured by Dr Wiglit and Mr
Arnott, nor Stahgmitis gambogioides, according to Murray and
Koenig, but is a species described by Lamarck and Gartner under
the name of Garcinia or Mangostana morella^ although it differs
from all of these genera in the structure of its stamens, and, there-
fore, probably ought to be considered a new genus among those
producing a ganibogioid juice.

Dr Christison proved, that, at the present time, Ceylon gamboge
is not an article of European commerce, and that the whole gam-
boge of the markets of this country comes, as in the time of Bon-
tius, from China. After mentioning the analysis of fine gamboge
made by Braconnot in France and John in Prussia, he stated the
following as the mean composition of the several varieties of gam-
boge he has hitherto examined : —

Pipe gamboge of Siam : Resin, 72.2 ; Arabin, 23.0 ; Moisture, 4.8 ;=100.0.
Cake gamboge of Siam: Resin, 64.8 ; Arabin, 20.2 ; Fecula, 5.6; Lignin, 5.3
Moisture, 4.1;=100.0. Ceylon gamboge sent by Mrs Colonel Walker
Resin, 70.2 ; Arabin, 10.6 ; Fibre of wood and bark, 5.6 ; Moisture, 4 6
Ceylon gamboge, adhering to a specimen of the bark sent by Mr David An-
derson Blair : Resin, l^.br, Arabin, 18.3 ; Cerasin, 0.7; Moisture, 4.8;=99.3.

The proportion of the gum to the resin varied somewhat in each
variety, but never differed more than 2 per cent, from the means
given above.

The author added, that he had found the resin to be the active
principle of gamboge-
He inferred from the composition of the different kinds of gam-
boge, and other circumstances detailed in his paper, that the cake
gamboge of Siam is not entirely a natural production, but a manu-
factured article : that Ceylon gamboge, if freed from incidental
fibrous matter, corresponds almost exactly with Siam gamboge :
that, therefore, they are probably produced by the same plant :
that Ceylon gamboge possesses precisely the same medicinal pro-
perties : and that this variety, if more carefully collected, may, in
all probability, be applied with equal advantage to every economi-
cal purpose which is at present served by the finest pipe gamboge
of Siam.

Proceedings of the Wernerian Natural History Society,
{Continued from vol. xx. p. 423.)

1836, March 12 Robert Jameson, Esq. P. in the Chair. The

Secretary read Mr Richard ParnelFs account of the occurrence of
the White-bait, Clupea alba, in the Frith of Forth, in considerable
abundance ; and also his description of the Sprat or Garvey-herring,
C. sprattus.

March 26. — David Falconar, Elsq. formerly V. P. in the Chair.
The Secretary read an account of the Tadpole fish, Raniceps tri'

Proceedings of the Wernerian Society. 161

furcatusy and of the Sea-snail, Cyclopteris liparisy observed by him
in the Frith of Forth, and specimens of both were exhibited. Mr
Wilson, for the Secretary, then read Remarks on the Vitality of
the Toad, communicated by the Rev. Edward Stanley of Alderley
Rectory.

Dr Thomas Aitken gave an account of the anatomy of a specimen
of the Ursine Sloth, Vrsus lahiatus, which died a short time ago
in a travelling menagerie, while at Edinburgh, demonstrating tbe
peculiarities of the organs of respiration and digestion. The
stuffed specimen of the animal was also exhibited.

Professor Jameson exhibited a series of birds from Northern
India, collected by Mr Hamilton Stirling, which, he remarked, was
remarkably inf cresting, as presenting many species which were not
known to exist in that quarter. Mr William Jameson pointed
out several of these ; of the rapacious order he noticed the Mil-
vus govinda, and Accipiter dukhunensis, the former of which
was considered to be probably the young of the Falco Cheela.
With regard to the geographic distribution of the genus Milvus,
it was stated, that it occurs in all the different continents of the
Old World and New Holland, but that it has not as yet been de«
tected in the New World, its place being there supplied by the ge-
nus Nauclerus. Specimens of the Gypaetos barbatus were again laid
before the Society, Professor Jameson having many years ago exhibit-
ed this bird sent from Northern India by Lieutenant Tytler (which,
since that time, has been discovered by other travellers), for the
purpose of pointing it out under the form of the Vultur Niger, it
in the young state being considered as a distinct species, and de4
scribed under this name ; and also for the purpose of shewing that
it from the nest upwards, undergoes the same changes as the Euro-
pean species, a character, before all others, marking them to be one
and the same species. In regard to British birds in general, in
connection with Indian ornithology, Mr Jameson stated, that more
than one-third of them occur in India, either identical with, or under-
going certain slight modifications in the colour of the plumage, size,
&c., characters which,if their habits and manners are the same, would
lead him to consider them rather as marked varieties than as new
species. To the diurnal rapacious birds Mr Jamesou particularly
directed the attention of the Society, and stated, that of the 18
diurnal birds of prey found in this island, the following striking*
distribution was presented, viz. In common with Europe 3 ; Europe
and Asia 2 ; Europe, Asia, and New Holland, 1 ; Europe, Asia

VOL. XXI. KO. XLI. JULY 1886, L

162 Proceedings of the Wernenan Society,

Africa, and New Holland 3 ; Europe Asia, and North America, 5 ;
if, however, the Circus cineraceus exists in North America, which
is not at all improbable, we will have 6 ; Europe, Asia, and South
America, 1 ; Europe and North America 3, To these conclusions,
Mr Jameson remarked, he had come, principally from an examina-
tion of the magnificent collection in the Museum of the University
of Edinburgh. After some other general observations on the iden-
tity of particular species of rapacious birds, in which it was stated,
that the Falco cherrug of Gray, is the female of the Falco islandicus;
the Circus pallidus, Sykes, the young male of the Circus cyaneus ; tlm.
Circus variegatus, the Circus ruf us, &c. ; Mr Jameson exhibited spe-
cimens of the Gallus bankiva in its various stages, and remarked, that
it is probably one of the originals of the domestic fowl, which seems
to have originated not from one, but from many species; Bucco gran-
dis; Phasianus albo-cristatus in its various stages; Parus (Leiothrix^
furcatus, Temminck ; Cinclus Pallasii, Temminck. With regard to
the characters assigned to the genus Leiothrix by Swainson, of which
the Parus furcatus is the type, and which has been justly separated
from the true Pariadse, some observations were made, shewing that
several of these are quite inapplicable to the type of the genus.
lo exhibiting the Cinclus Pallasii, Mr Jameson remarked, that ther
genus was confined for many years to but one species, the exist-
ence of the Pallas dipper being called in question, and that not
found out of Europe. Now, however, we have three, and probably
a fourth (a bird existing in the collection of the University of Edin-
burgh, which may be placed in this genus, or rather forms a connect-
ing link between the genus Cinclus and that of Pitta), some of which
are found in all the great continents of the world, with the excep-
tion of New Holland. That the Cinclus Pallasii is the same as the
Cinclus Americanus, an opinion advocated by L. Bonaparte, can
only be maintained by those who have not had an opportunity of
comparing the two species, being very apt to bo misled by the-
meagre description of the former by Temminck; one character alone,
distinguishes the two species, viz. the Pallas Dipper is more than a
third larger than the American ; moreover, the latter never as-
sumes the colour of the former, at least Mr Jameson was unable
to detect, in a series of specimens of the Cinclus Americanus, in the
Museum of the University of Edinburgh, the slightest approach
to the tinge of colour assumed by the Pallas Dipper, A specime»
of Wryneck (Yunx torquilla) was exhibited, which was killed in
February last in Fifeshire.

Proceedings of the Werner Ian Society, 163

Mr Stirling being about to return to India, was elected a cor-
responding member of the Society. The meeting authorized the
purchase of a complete coloured copy of the " Zoological Journal,'*
for the Society's library.

April 16. — Dr R. K. Greville, formerly V. P. in the Chair.
A notice was read on the dolomization of the marble limestones of
Skye, with analyses of the same, shewing their magnesian character.
The author also stated his views in regard to the geognostical rela-
tion of the Plutonian rocks of Skye, which he referred to the por-
phyry and trap formations. He noticed, besides, the rock of St
Kilda and the granite of Arran, both of which exhibit several of
the characters of the porphyry series, and may probably, in a
geognostical sense, be considered porphyries rather than granites.
The blunders in observation, and the wholesale appropriation to
himself of the geology of Scotland (in despite of all the published
and unpublished accounts of Scottish, English, and German geolo-
gists,) by Dr MacCuUoch, were noticed ; and it was remarked by
several members, that a better spirit was now generally abroad, and
that few were disposed to follow in the path of the author of the
Geology of the Hebrides.

Mr Torrie, Assistant Secretary, read a communication from Ed-
ward Hamilton Stirling, Esq. on the Calaite or Mineral Turquois
Mines of Nishapur in Persia.

James Robertson, Esq., Mining Engineer (who is appointed by
the government at Teheran to conduct mining operations in Persia)
was elected a corresponding member.

April 30 Robert Ja3IESon, Esq. President, in the Chair. Mr

Torrie read a letter from M. de Moligny, dated Besan^on, 8th
September 1835, giving an account of a tremendous fall of the
mountain called the Dent du Midi. It was therein stated, that a
space of about two square leagues, extending from the base of the
mountain to the Rhone was covered by the debris, in some cases
to the depth of ten or twelve feet.

Professor Jameson took notice of a shower of hail which had occur-
red immediatelybefore the time of meeting this day, mentioning that
he and several other members of the Society had examined the hail-
stones, and ascertained that they were crystallized in the form of dou-
ble six-sided pyramids, and at the same time of larger size than usual.

The Society adjourned till November next.

( 164 )

Proceedings of the Society for the Encouragement of the Useful
Arts in Scotland.

. The Society for the Encouragement of the Useful Arts met
in the Royal Institution, on Wednesday the 9th Marcli 1836,
at 8 o'clock P.M. Mr Professor Forbes, Vice-President, in
the Chair.

The following Communications were laid before tlie Society : —

1. Suggestions as to the probable good effects of employing
Caoutchouc in solution in the manufacture of Ropes ; and for brush-
ing over the standing rigging, sails, &c., of ships. By Mr Thomas
Johnston, 137 George Street, Glasgow.

2. Letter from the Secretary of the Manchester Mechanics' In-
stitution regarding copy of the Society's Proceedings ; and sending
a copy of Lord Brougham's Address to the members of that Insti-
tution on 21st July 1835.

3. Suggestion of a new experiment whereby the Rotation of the
Earth may 1n) demonstrated. By Edward Sang, Esq. Vice-Pres.
Soc. of Arts.

4. Embossed Maps for the Blind ; and specimens of Printed
Music for their use, upon a new principle of Notation, applicable
to Music in general ; with Observations. By Mr James Gall jun.
24 Niddry Street, Edhiburgh.

5. Observations on the Dublin and Kingston Railway. By
David Stevenson, Esq. 1 Baxter's Place, resident engineer for
Granton Harbour.

6. Report by Mr Patterson of the Fire-engine Establishment on
Mr Adam Hope's new Nose-pipe for Fire-engines, was read and ap-
proved of.

^ 7. The committee on Mr Macpherson's bath-heater gave in their
report, which was read and approved of.

8. The Report of the Prize Committee, containing the List of
Prizes offered by the Society for Session 1836-7, was read, and
printed lists of the prizes distributed.

9. The Report of the Prize Committee awarding the Prizes for
Session 1834-5 was read, and the prizes were delivered to the
successful candidates by the Vice-President, with appropriate ad-
dresses, in the order of that Report, which is as follows : —

(1.) To Mr D. Landale mining-engineer, Wemyss, Fifeshire —
for his Method of carrying Low-pressure Steam to the distance of
193 yards, to work a steam-engine for draining a coal-mine ; read
22d April 1 835. Tiie Society's Gold Medal, value Fifteen Sovereigns.

(2.) To Mr William Meikle, Townend, Strathaven, Lanarkshire
— for his New Reed Instrument, called the " Caledonica," and for
his improved Oboe and Bassoon ; exhibited and described 28th Ja-
nuary 1835,— The prize " for the best set of experiments on any

Proceedings of the Sockttj of Arts, 165

branch of Practical Mechanics," being the Society's Gold Medal,
value Ten Sovereigns.

(3.) To Mr Robert Muir (of Muir, Gowans, and Co. printers),
42 Argyle Street, Ghisgow — for his communication " On the best
Composition for Rollers employed in applying the Ink to the Types
in Letterpress Printing, especially with a view to preserve their
adhesive and elastic properties in as uniform a condition as possible)
during damp and other variable states of the atmosphere ;" read,
and specimen roller exhibited for trial, 11th March 1835.— The
Society's Silver Medal, value Ten Sovereigns.

(4.) To Mr John Weir, venetian-blind maker, 35 Gordon Street
Glasgow — for his new and improved method of Raising and Lower-
ing the Venetian-Blind ; and for his improved Pincers for drawing
Nails ; exhibited and described 25th March 1835. — The Society's
Silver Medal, value Five Sovereigns.

(5.) To Mr David Kemp, smith, Fox's Lane, Leith — for the in-
genuity displayed by him in his Latch-Lock of a new construction
— and his Chest or Desk-lock; exhibited iOth December 1834.—
The Society's Silver Medal, value Five Sovereigns.

(6.) To J. Stewart Hepburn, Esq. of Colquhalzie, Crieff — for his
essay on the causes of Obstructions in Water Pipes and Syphons
by disengaged air ; and the construction of an Air Extractor for
removing them ; read, and model and drawings exhibited 5th Feb-
ruary 1834. — The Society's First Honorary Medal.

(7.) To David Stevenson, Esq. 1 Baxter's Place, Edinburgh, re-
sident engineer for Granton Harbour — for his Observations on
the Manchester and Liverpool Railway ; read, and illustrative
drawings exhibited, 25th February 1835. — The Society's Second
Honorary Medal.

(8.) To George Martin, Esq. 108 George Street, Edinburgh — for
his Remarks on the Glasgow and Garnkirk Railway ; with illustra-
tive sketches ; read, and exhibited 22d April 1834. — The Society's
Third Honorary Medal.

(9.) To Mr James Dowie, boot and shoemaker in ordinary to the
King, 57 Frederick Street, Edinburgh, M.S. A. — for his notice of
an improved form of Boots and Shoes adapted to the comfort of
the wearer; read, and specimens exhibited, 20th May 1835. — The
Society's Fourth Honorary Medal.

The Committee reported that there had been no competition
for the following prizes : —

1st Prize (Keith Medal) of . . 20 Sovereigns.
3d — of ... . 8 —

4th — 1 T . - u- T> • r of 12

c.i > Lithographic Prizes < c a

6th — of 10 —

March 30. — Edward Sang, Esq. Vice-President in the chair.

The following communications were laid before the Society : —
(1.) Description and Drawing of a Wind- Safe for Grain and Hay

l^^acks. By Mr Thomas Johnstone, 137 George Street, Glasgow.

166 Prcceedings of the Society of Avis.

(2.) Degcription of a Plan by which the Blind may be taught to
write a common Current Hand, as small and as elegant in its forms
^s that generally used by those who see. By Mr James Gall jun,
printer, Edinburgh, M.S.A.

(3.) Description of a New System of Arithmetical and Geometrical
Notation for the Blind, in which no Apparatus is required further
than Common Pins and a Cushion (or any thing into which the
pins may be thrust, such as a soft Chair, or a bed), in order to per-
form the longest and most difficult calculations in Arithmetic and
Algebra, — and in Geometrical Problems the same are necessary,
with the addition of a pair of Wooden Compasses, one leg of which
is a straight edge, and the other a scale for measurement. By the
same.

(4.) Remarks on Pointing Naval Ordnance ; and Suggestion of a
new method of ascertaining the precise moment when a Gun ar-
rives at horizontal position. By T. B. College, Post-office, Edin-
burgh.

(5.) Donation. — On the manner in which Friction affects the mo-
tions of Timekeepers. By Edward Sang, Esq. teacher of mathe-
matics, Edinburgh, M.S.A. &c., July 1835. From the Author.

(6.) The Committee on an Alphabet and mode of Printing for the
use of the Blind, reported progress.

(7.) The Committee on Mr Macgregor's Escapement reported.

The following Candidates were admitted as ordinary members,
viz :-^

1. Mr James Mackay, Goldsmith, 24. Forth Street ; 2. J. Stewart
Hepburn, Esq. of Colquhalzie,by Crieff"; 3. Mr Alexander Stewart,
painter, 88 Prince's Street.

April 13 Mungo Ponton, Esq. Councilloz', in the Chau*. The

following communications were laid before the Society: —

(1.) On a Systematic Method of Measuring Surface and Solidity.
By Mr John Sang, land-surveyor, Kircaldy.

(2.) Description and Drawing of a Simple plan for enabling Blind
persons to communicate in Writing with their seeing Friends. By
Mr John St Clair, teacher of music, Monteith's Close, 61 High
Street, Edinburgh. The Writing-Board was exhibited.

(3.) On the Use of Steam in the Economizing of Fuel. By An-
drew Fyfe, Esq. M.D., M.S.A.

{ (4.) Notice of a New Pocket Box Circle, for making Observations
at Sea or on Land. By William Galbraith, Esq. teacher of ma-
thematics, Edinburgh, M.S.A — The Instrument was exhibited.

(.5.) Notice of an Improvement in the Construction of Wollaston's
Goniometer. By Edward Sang, Esq. teacher of mathematics,
Edinburgh, Vice-Pres. Soc. Arts. — The Apparatus was exhibited.

The following candidates were admitted as Ordinary Members,
viz.

1, Cunninghame Borthwicfc, Esq. 27 Albany Street ; 2. James Graham,
Esq. of Leitchtown, 2 Rutland Square; 3. John Thomson, Esq.
professor of music, 32 Koyal Circus.

Proceedings of the Society of Art«, 167

' April 27. — Edward Sang, Esq. Vice-Pres., in the Chair. The
following communications were laid before the Society : —

(1.) Drawing and Description of a Machine for cutting MortiSeS
in Joinerwork, &c. By Mr J. Kirkwood junior, wright, Glasgow.
A specimen of the work was exhibited.

(2.) Description and Drawing of a New Method of raising and
lowering a Slide-Rest, by means of Inclined Planes moved with
Screws. By Mr James Bell, philosophical instrument maker, 54
South Bridge Street, Edinburgh. Communicated by Mr Alexander
Bryson, M.S.A. — Tiie Tool was exhibited.

(3.) Six Specimens of Lithographic Printing, from Transfer Draw-
ings, in competition for the 2d Prize for 1833-6. — As also, Three
Specimens of Lithography executed entirely with the Pen, but too
small for competition for the above Prize. By Messrs Maclure and
Macdonald, lithographers, 160 Trongate, Glasgow.
"■■ (4.) Twelve Specimens of Lithographic Printing, chiefly from
Transfer Drawings. By Mr Samuel Leith, lithographer, late of
BanflF, now of Leith and Smith, lithographers, Hanover Street, Edin-
burgh.

(5.) On a Fire-Engine for Ships. By T. Borthwick, Esq. 1
Broughton Place, Edinburgh.

(6.) On the Construction of a High Pressure Steam-wheel. By
the same.

(7.) A new System of Short-hand Writing. By Mr J. Kerr,
teacher of stenography, and land-surveyor, 63 South Bridge,

Edinburgh Specimens in illustration, and for comparison with

other systems now in use, were exhibited,

Mr John Sang, land-surveyor, Kirkcaldy, was admitted as an Ordinary
JMember.

The President then took occasion to express his own regret, and
that of the Society generally, that no competitors had appeared for
the other and particularly the lithographic prizes offered last session.
He stated, that the Society have no wish to store up the funds
committed to their charge, but that it is their anxious desire to af-
ford every encouragement to competitors ; in proof of which he
alluded to the greater liberality of the offer for next session. The
adjudgment of the prizes he also stated to be free of every objec-
tion. They are awarded, in fact, by a committee appointed for
that especial purpose after all the communications on which they
are to decide have been submitted to the Society ; and the appoint-
ment of that committee is by the Society at large, and not merely
by the Council ; so that candidates may rely on an impartial consi-
deration of the merits of their inventions.

The Committee proposed that, while thanks were doe to all
those gentlemen who had sent them communications, the special
thanks of the Society should be given to the following gentlemen
for their valuable communications, viz. —

1. To Mr Professor Forbes, Edinburgh, F.R. SS.L. & E. Vice-
President Soc. Arts^for his communication on the application pf

168 Proceedings of the Society of Arts »

the Compressibility of Water to practical purposes ; read 22d
April 1835.

2. To the Rev. Edward Craig, A.M. Oxon. Counsellor Soc. Arts
—for his notice of arrangements for Measuring the Angles of Crys-
tals viewed under a high magnifying power ; read and exhibited
20th May 1835.

3. To Mr John Dunn, optician, 50 Hanover Street, Edinburgh,
Curator Soc. Arts — for his new Klinometer, which serves as a por-
table surveying instrument, or Theodolite; exhibited 22d April 1835.

4. To Mr James Edgar jun. 6 Newington Place, Edinburgh —
for his model and description of a method of constructing Wooden
and other Bridges ; read and exhibited llth February 1835.

5. To Mr John Adie, optician, 58 Prince's Street, Edinburgh —
for his notice of a new method of Cutting, Drilling, and Working
Glass, Porcelain, &c., by means of Turpentine ; communicated to
him in London.

The following gentlemen were admitted as ordinary members,
viz —

1. Mr James Gall jun., printer, 24 Niddry Street; 2. Mr William Gal-
braith, teacher of mathematics, 54 South Bridge ; 3. Mr AValter
Sibbald, ironmonger, 8 Meadow Place ; 4. John 11. Skinner, Esq.,
Vv W.S., 5 Roxburgh Place.

May 25. — Mr Professor Forbes, Vice-Pres. in the chair. The
following communications were laid before the Society : —

1. A new Anemometer, by which the most minute changes in
the force or velocity of the wind, or current of air, may be mea-
sured. Invented and constructed by Mr R. Adie, optician, Liver-
pool. Communicated and described by Mr John Adie, optician,
Edinburgh.

2. On the Construction of a Fluid Engine, acting by Atmos-
pheric Pressure. By Mr T. Borthwick, 1 Broughton Place, Edin-
burgh.

3. On the Effect of Atmospheric Pressure on the Steam-Engine,
as usually constructed. By the same.

4. On condensing by contact. By the same.

5. On Substitutes for Paddle- Wheels in Steam-Boats for Canal
Navigation. By the same.

The following Reports of Committees were read and approved
of, viz. —

6. On Smithes Instrument for Cutting Coats.

7. On Gall's Maps for the Blind.

8. On fall's New Notation for Music.

9. On Gall's Plan of Teaching the Blind to Write.

10. On Gall's New System of Arithmetical and Geometrical
Notation for the Blind.

11. On St Clair's Writing Board for the Blind.

12. On Dr Fyffe's Use of Steam in economizing Fuel.

13. On Mr Galbraith's Pocket Box Circle.

14. On Mr Sang's Improvement in the construction of Wollaston's
(^oiometer.

Scientific Intelligence. — Meteorology. 169

15. On Kirkwood's Morticing" Machine.

16. On Bell's Method of raising and lowering a Slide-Rest.

17. On Whitelaw's additions to the Turning Lathe in slow
turning.

18. Professor Forhes pointed out to the Society the prohably
extreme practical importance of a most extraordinary fact in op-
tics communicated lately to the Institute by M. Cauchy. He was
led to anticipate by theory, and verified it experimentally, that
near the limit of total reflection in a prism refraction takes place,
with a vast increase of intensity of the incident ray of light. If this
be confirmed (and the proof is easy, though Mr F. has not had leisure
to put it to the test), the most astonishing results, the Vice-Presi-
dent pointed out, would ensue ; since light, however trifling, may
be magnified indefinitely.

SCIENTIFIC INTELLIGENCE.

METEOROLOGY.

1. Shower of Falling Stars in Russia., on the night between
the \9.th and ISth November 1832. — The following extract of a
letter from Monsieur le Comte de Suchteln to Monsieur Feo-
dorou, was communicated to the "Royal Academy of Sciences" at
Paris, in which mention is made of numerous meteors which were
seen in the neighbourhood of Orenburg, in the night between the
12th and 13th November 1832. " In the night between the 12th
and 13th November 1832, between three and four o'clock in the
morning, the wealher being calm and serene, and the thermo-
meter being at 55° of Fahr., the heavens appeared to be be-
spangled by a great number of meteors, which described a great
arch in the direction of from north-cast to south-west. They
burst like rockets,into innumerable small stars, without producing
the slightest noise, and left in the sky, what was long of disap-
pearing, a luminous band, having all the various colours of the
rainbow. The light of the moon, which was then in her last
quarter, obscured this appearance. It sometimes seemed as
if the heavens were cleft asunder, and in the opening, there
appeared long brilliant bands of a white colour. At other limes
flashes of lightning rapidly traversed the vault of heaven,
eclipsing the light of the stars, and causing these long luminous
bands of varied colours to appear. These phenomena continued
to succeed each other without occasioning the slightest percep-

?^d Scientific Intelligence, — -Geology.

tible noise. They were in their greatest splendour between five
and six o^clock in the morning, and continued without interrup-
tion till sunrise. They were observed principally by the sen-
tinels and by the officers, when going their rounds ; also by the
ecclesiastics, and by the subordinates, in the cathedral, and by
many other persons. Monsieur Milordou, the principal priest
pf the cathedral, stated, in the account which he gave of this oc-
currence, that the interior of the cathedral was sometimes sud-
denly illuminated by the light of this brilliant phenomenon. Mon-
sieur Itschitow, Lieutenant-Colonel of the 3d Battalion of the
Line of Orenburg, also confirmed these statements in his Re-
port, which, as an additional ground of confidence, contained
the accounts of the sentinels in the several positions in which
they had been posted. During the same night, and almost at
the same hour, a not less remarkable appearance was witnessed
at Hitzkaja-Saschtschita, about seventy-five miles to the south
of Orenburg. Two columns of a white colour rose from the
horizon equidistant from the moon, which at the time had not
risen far ; about the middle of their height they appeared bril-
liant and much curved. Several horizontal bands sprung from
this point, the most brilliant of which extended towards the
moon, in which they appeared to unite, so that in this way they
appeared to form a great H. In the town of Ufa, the seat of
the government of the same name, situated 380 miles to the
north of Orenburg, a phenomenon similar to that which was
observed at Hitzkaja-Saschtschita, was perceived, but, according
to the accounts which have been given, it was not quite so bril-
liant."

GEOLOGY.

2. Disengagement of InJlammaUe Gas in the Interio?- of
Coat Mines. — Monsieur Combes has presented a notice to the
Royal Academy of Sciences at Paris, which may serve as a sequel
to the remarks of Mr Buddie, an English engineer, upon the
evolution of hydrogen gas in coal-mines. It seems quite cer-
tain, as stated in this notice, that the evolution of carburetted
hydrogen in coal-mines, has frequently a relation to the pres-
sure exercised externally at the surface, so that there is no dis-
engagement where the external pressure is considerable, and

Sddntific Intelligence — Geology, 171

it becomes more and more, abundant in proportion as this pres-
sure is diminished. Besides, the pressure under which the gas
commences to be evolved from the pores of the coal, varies in
different mines. It is sometimes scarcely superior to the common
pressure of the atmosphere, as without doubt is the case in many
of the mines in Northumberland, in which, according to Mr
Buddie, the atmosphere becomes explosive when the barometer
is low, whilst scarcely a trace of inflammable air is to be found
when the barometer is very high. At other times, it exceeds con-
siderably the pressure of the atmosphere. Monsieur Combes states
the following as a proof of this. We give the statement in his
own words. " In the year 1830, 1 caused the shaft of a coal-pit
at Latour, near Firmini, Department of the Loire, to be emptied
of the water it contained. This pit had for many years been
abandoned, on account of the immense quantities of inflammable
air which had been generated in the galleries, which had occa-
sioned so many deplorable accidents, that the working could not
be continued, on account of the imminent risk. The pit was
230 feet deep at the place where it reached the roof of the gal-
leries in the coal, and it was filled with water to within Q5 feet
of the surface. This free portion of the pit contained only at-
mospheric air, without a single trace of carburetted hydrogen.
When the water was pumped out to the depth of 193 feet from
the surface, the roof of the galleries being still covered with wa-
ter to the extent of 37 feet, the gas began to be disengaged
through the column of water still in the pit, with a noise such as
a copious spring would have made by faUing from the upper
part of the shaft. After this event, the air in the pit continued
to be in the highest degree explosive. One day two workmen
incautiously descended into the pit to discover the spring, which
they supposed issued from the upper part of the shaft ; they
took a common lamp along with them, and when they had de-
scended about 45 feet, their lamp set fire to the gas ; when, for-
tunately enough, only the upper layer exploded. One of the
workmen was severely scorched. When they had ascended to
the surface, and a wisp of burning straw was thrown into the
pit, a very great explosion was the immediate result. Thus, in
this mine, the inflammable gas was evolved under a pressure at
least equal to two atmospheres, and probably much more ; the

172 Scientific Intelligence — Geology,

shaft was in fact opened upon the most elevated portion of the
workings, and all the galleries communicating with it had a ra-
pid descent, following the inclination of the bed, which was at
an angle of 18° or 20°. The escape of the gas through this
depth of water continued without interruption, with the same
intensity, during several months. I may add, that, after I
had caused a horizontal floor of planks of fir to be constructed,
and covered over with ^about six feet of stiff clay, well pressed
down, and sunk to the bottom of the shaft, the gas escaped much
more sparingly across the fissures of schistous rock, but still in
very considerable quantities. In those beds which retain the
hydrogen only under such great pressure, it is manifest that the
quantity will vary to a very trifling extent, with the variations
of the barometer. Nevertheless, in certain circumstances, the
air in the mine is more charged with gas, as during the time of
a storm, when the barometer is low, than in calm and fine wea-
ther, with a dense atmosphere." In the work to which this no-
tice is, as we have said, a kind of supplement, Mr Buddie, when
treating of the explosion which took place on the 3d of August
1830, in the coal-mine of Jarrow, points out two causes which
are the cause of explosions in the coal-mines in the north of
England ; 1^^, The numerous fissures and rents in the encasing
rock, which thus form cavities filled with gas, whence it issues
in greater or less quantities, according as the pressure of the
atmosphere is more or less; 2cZ/z/, Blind cavities in the coal-
seam itself, or in the surrounding rock, whence the gas suddenly
escapes, when the galleries reach and open them up. M. Combes
confirms the existence of this second cause of disengagement,
from the occurrence of accidents which have happened in French
mines; and, among others, by an explosion which happened on
the 10th of April 1824, in the coal-mine of Ronchamp, in
Haute-Saone, when twenty miners were killed, and sixteen most
severely injured. According to the reports of the engineers^of
the mine, inflammable gas had previously very rarely, and in
very small quantities, manifested itself in this mine. A trifling
disengagement had taken place in a try-work which was begun
at the bottom of the pit of St Louis, close to a fault. In a re-
port which M. Thirria gave in to the Director-General of
bridges, roads, and mines, he remarks, " It was imagined that

Scientific Intelligence, — Geology. 173

the gas might be got rid of by means of a ventilator, whicli
should propel it into a gallery of transport, in which the current
of air was so strong, that it sometimes blew out the lamps of the
workmen. The engineers supposed that the gas, instead of hav-
ing been forced out of the mine by the current of air, was forced
only into some old abandoned workings which were situated at
the extremity of the gallery of transport, behind pillars and
walls, and some rubbish ; and that it was there ignited, owing to
the falling down of a part of the roof of this cavity, whereby a
great quantity of the gas was suddenly expelled, or possibly
owing to some of the workmen having taken a lamp into it.
However this may be, the gas has begun to shew itself in the
works, in the neighbourhood of the fault of the pits of St Louis ;
and this circumstance recurring frequently in the mines, it be-
comes important to recommend it to the peculiar attention of
miners, and to point out to them the means of its prevention."

3. Analysis of a Clay Ironstone ^forming a bed twelve inches
thicTc, in the Coal Formation at War die, to the westxvard of New-
haven, near Edinburgh ; by William Gregory, Esq. M. D. —
No. 1. from a depth of twenty fathoms and five feet, contains in the
calcined state, as given to me in 100 parts. Matter insoluble in
acid (sand), 19 6 ; Peroxide of iron, 72 5 ; Alumina (clay), 3 5;
Lime (a trace), 0; Moisture and loss, 4 4; = 100. — No. 2.
from a depth of twenty-six fathoms and four feet, contains in a
calcined state in 100 parts. Insoluble matter, 37 8 ; Peroxide of
iron, 5Q 4 ; Alumina, 2 5 ; Lime (a trace), ; Moisture and
loss, 3 3; = 100. — No. \ when calcined contains, therefore,
about 50 per cent, of pure iron, calculated in the metallic state,
and No. 2, 40 per cent, nearly. — No. 3, in its natural state con-
tains in 100 parts, Insoluble matter, 19 3 ; Protoxide of iron,
45 9 ; Alumina, 1 5 ; Water and loss (a trace of lime) carbon,
&c. 33 3 = 100. — The metallic iron here is 32 2 per cent. ; the
reason of the difference is, that by the calcination a quantity of
water was expelled, so that in numbers one and two, the quan-
tity of iron is increased in proportion to the weight of the mine-
ral analyzed. All the ores are remarkably good, and there can
be no doubt that, with the addition of lime and other neceasary
fluxes, they will work admirably. I have scarcely seen any ores
of the coalfield containing so much as 45 per cent, protoxide ;

174' Sckntiftc IntelUgence.-^Geology.

and it is probable that Nos. 1 and 2 contain a good deal more
than this. All, I have no doubt, in the natural state contain,
as No. 3 does, some carbonaceous matter, but the quantity of
this is not large.* Dr Gregory adds, that the qnahty of the
ironstone of Wardie is not surpassed and scarcely equalled in
any iron-work in Scotland. — Communicated hy Captain Boswall
of Wardie,

4, Volcanos of Kamtschatha. — In the second volume of Er-
man''s travels, which is soon to appear, the following heights of
volcanos are given : The summit of the volcano of Kliutschewsk,
4804? metres above the level of the sea ; the summit of the vol-
cano of Tolbatschinsk, 2534 metres ; the summit of the volcano
of Schiveloutsch, 3214 metres. Kliutschewsk is the highest
point in the Peninsula of Kamtschatka. The limit of perpetual
snow is 1618 metres.

5. Temperature of the Mines at the Leadhills and of some
Springs on the Rhine. — On occasion of a late visit to the district of
Leadhills (says Professor Forbes, in a note to the editor), I sug-
gested to my friend and former pupil, Mr Irving of Newton, the
importance of determining the temperature of the springs in the
bottom of Leadhill mines at this particular epoch ; the workings
having been discontinued since the end of March, any supposed
influence of animal heat and lights is avoided, and yet the pump-
ing of the water has been regularly carried on. Mr Irving
immediately and zealously undertook the inquiry, and descend-
ed to the deepest part of the mine on the 16th of May, and
found the temperature of the water m the bottom to be 49°.
This was at a depth of ninety-five fathoms below the Barrow
Road or entrance to the Susanna vein. A spring at the upper
level had a temperature of 44°. The temperature of the air at
seventy-five fathoms, where there was free circulation, was 53°,
and at about half that depth, also in a current, it was only 50°,
The facts are therefore entirely in accordance with published
observations on the increase of temperature with depth, and are,
I presume, the first of the kind made with care in Scotland.

* The ironstone of Wardie is also interesting not only on account of the
coprolites it contains, but also from its having afforded many new and rare
fossil fishes, discovered there by Lord Greenock, of which descriptions and
figures have been published in Agassiz's great work on fossil fishes.

Scientific Intelligence. — Geology, 175

Mr Irving has promised to pursue these experiments, and \
have procured for him some of the standard instruments espe-
cially designed for this purpose furnished by the British Asso-
ciation. — In relation to an interesting class of facts noticed in
M. BischofTs paper on the temperature of springs in the last
number of your Journal, namely, that many springs have a
mean temperature a few degrees above that of the air at the
place, I beg to add my testimony from observations made in
the volcanic country of the Rhine. I am scarcely yet prepared
from the testimony of ray own observations to consider the fact
to be so general as the German naturalist . supposes. The fol-
lowing extract from my journal will shew that in the particular
cases in question I had arrived at the same conclusion, but that
I was disposed to attribute the effect to a local cause : — " M
August 1832. — Near the lower quarry [of Bell near Obermen*
nig], and in the bottom of the valley, rises a very fine mineral
spring, very similar in every respect to that of Tonistein [near
Laach]. It contains more iron, and the quantity of carbonic
acid [gas] evolved is perfectly enormous. Both springs have
their origin in nearly similar circumstances, namely, at a ju^iCr
tion of tufa with clayslate. Their temperature, it is remarkt
able, is almost the same, that of Tonistein being 5S°5, that of
the present one (which is near Obermennig, and is called the
Kesselbron, according to Hibbert) 54.°2. Its height must be
considerably above the other. Rising as these springs do from
valleys of common clayslate merely filled up .with accidental
eruptions [of trass or volcanic mud], may we not conclude that
the progress of secular refrigeration has not yet reduced the
temperatures of the lower strata of the difficultly conducting
mass of tufa to the mean temperature of the place, which these
extremely copious springs certainly exceed by several degrees."!
6. Progressive Rise of a portion of the bottom of the Medi*
terranean. — M. Theodore Virlet lately addressed a note to the
French Academy of Sciences, in which he directed the attention
of geologists to the probability of the speedy appearance of a
new island in the Grecian Archipelago, in consequence of the
progressive rise of a sunken solid rock (composed of trachytic
obsidian ?) in the gulf of the volcano of Santorin. The follow-
ing are the author's observations on this subject : — ^ Towards

116 Scientific Intelligence. — Geology.

the end of the last century, at the period when Olivier visited
Santorin, the fishermen of the island asserted that the bottom of
the sea had recently risen considerably between the island of
Liittle Ka'imeni and the Port of Thera ; in fact the soundings
did not give a greater depth than fifteen to twenty fathoms,
"where formerly the bottom could not be reached. When Co-
lonel Bory and the author visited the island in 1829, they were
able not only to confirm the truth of Olivier's statement, but
also to ascertain, by various soundings, that the rise of the sub-
marine land had continued, and that at the point indicated the
depth was not more than four fathoms and a-half. In 1830
the same observers made new soundings, which enabled them
to determine the form and extent of the mass of rock, which in
less than a year had been elevated half a fathom. It was found
to extend 800 metres from east to west, and 500 from north to
south. The submarine surface augmented gradually to the
north and west, from four to twenty-nine fathoms, while to the
east and south this augmentation amounted to forty-five fa-
thoms. Beyond this limit the soundings indicated in all direc-
tion^ a very great depth. I have lately been informed that Ad-
miral Lalande, who, since 1830, has twice returned to Santorin,
ascertained that the rock still continues to rise ; and that, in
September 1835, the date of his last visit, the depth of water
amounted to only two fathoms, so that a sunken reef now exists
which it is dangerous for brigs to approach. If the rock conti-
nues to rise at the same rate, it may be calculated that, in 1840,
it will form a new island, without, however, those catastrophes
which this phenomenon seems to presage for the gulf of Santo-
rin, being a necessary consequence of the epoch of its appearance
at the surface of the water. Since the eruptions of 1707 and
1712, which produced the new Kaimeni, volcanic phenomena
have completely ceased in the gulf of Santorin, and the volcano
seems at the present day quite extinct. Nevertheless, the rise
of a portion of its surface seems to demonstrate continual efforts
to make an eruption during fifty years; and that, whenever
the resistance shall not be strong enough to offer a sufficient ob-
stacle, the volcano will again resume its activity."

7. Remains of Quadrupeds in the Oolitic System of Rocks. —
Hitherto the only fossil remains of the mammalia known to na-

Scientific Intelligence — Geology. 177

turalists, older tlian the chalk formation, were those of a species
of Opossum, or Didelphis, found in the oolitic rocks of Stones-
field. Some years ago, Hugi, professor at Soleure, discovered,
in quarries in that part of the oolitic system named Portland
Stone, remains of true quadrupeds. Very lately, these neglected
observations of Hugi have, we are told, been confirmed and
strengthened by additional discoveries in the same quarter, made
by a Mr Gressy. He, in a communication to the Natural His-
tory Society of Strasbourg, enumerates the following animal re-
lics as having been found inclosed in undoubted beds of Port-
land stone, along with remains of crocodiles, emys or fresh-water
turtles, &c., viz. bones of Paleotherium, the Anoplotherium gra-
cile, of a kind of hedgehog, and a pachydermatous or ruminating
animal, the size of a sheep.

8. Temperature of the different Tertiary Deposits at the
Epoch of their Formation, — M. Deshayes has communicated to
the French Academy of Sciences a notice on the determination
of the temperature of the tertiary periods of Europe from the
knowledge of the fossil shells which these formations contain.
The author commences by detailing rapidly some facts relative
to the distribution of molluscous animals in proceeding from the
north to the south, and principally from the North Cape to the
Gulf of Guinea. " If" (says he) " we take as a whole the small
number of species living in the north, we can divide them into
two perfectly distinct categories : the one series peculiar to the
cold seas and never passing their limits ; and the other, includ-
ing a smaller number, living also in the temperate seas of Ger-
many, France, and England, with the species belonging to these
seas. In examining the mollusca of our temperate sea?, in which
there exists a larger number of species than in the seas of the
north, it is easy to divide them into three series. In the first
are included the species I have just indicated, those which ex-
tend to the seas of the north ; the species of the second series
extend to the southern seas ; and those of the third are peculiar
to temperate seas. In the intertropical region similar pheno-
mena present themselves. There we find a greater number of
species than in the two preceding regions ; and if some among
them occur also in the temperate region, a large proportion are
peculiar to the equatorial regions. These, thelp^ are the general

VOL. XXI. NO XLT. JULY 1836. M

178 Scientific hitelligence — Geology.

facts, and we may already draw from them the general conse-
quence that each group of species represents the mean tempera-
ture of each of these regions. But there are certain species of
more local and others of more general occurrence. Thus, to
give an example of the latter, the Buccmum undatum is found
from the North Cape to the Senegal, modified according to the
temperature ; and it is easy to distinguish the varieties peculiar
to the three principal conditions of temperature. Other species,
more sensible to the influences of temperature, are much more
local, and they are precisely those which it is the most important
to know. The following are some of them. The Buccinum
glaciate and Cardium Groenlandicum do not extend beyond the
polar circle, and are found in Norway and Greenland. The
Terehratula psittacea lives between the fifty-fifth and seventy-'
fifth degree. In my opinion these species and several others
represent the mean temperature of the north of Norway.
The Tellina Baltica, Patella 7ioachina, Natica clausa, Pa-
tella iestudinalis, several species of the genus Astarte, and
some other species, seem to me to represent the mean tempera-
ture of the north of England, the south of Sweden, and Den-
mark. In the English Channel, on the coasts of France and
England, there exist several species peculiar to our temperature,
such as the Psammobia vespertina, Pecten irregularis^ &c. The
coasts of Spain and Portugal are less known than those of New
Holland and North America. Among the large number of
species known in the intertropical zone, tlicre are a great many
which are peculiar to it, and which, accustomed to a high and
little varying chmate, do not occur living in any other part of the
surface of the globe ; they express then with fidelity the tempera-
ture of the seas in which they live. These facts relative to the
coincidence of the temperature with the presence of certain
species, necessarily preceded the remarks which I have to make
regarding the temperature of the geological epochs of tertiary
deposits. I ought to add that, in order to determine this inte-
resting question, it was necessary to compare carefully all the
known Hving species with all those found in the various tertiary
formations of Europe. The following are the principal results
obtained by the aid of this long investigation : — 1 . The tertiary
formations of Europe do not contain a single species in common

Scientific Intelligence — Geology. 179

with ihe subjacent secondary formations ; 2. The tertiary for-
mations are the only ones containing fossil remains of species
which live at the present day ; 3. The analogous species are
more numerous in proportion as the formation is more modem,
and reciprocally ; 4. Constant proportions (Sin 100, 19 in 100,
52 in 100), in the number of analogous species, determine the
age of the tertiary formations ; 5. The tertiary formations are
in superposition, and not in parallelism, as was at first suppo-
sed ; 6. The tertiary formations ought, according to their zoo-
logical characters, to be divided into three groups. We shall
now give the conclusions relative to the temperature of the three
series of tertiary strata at the epoch of their formation. The
most superficial tertiary formations were deposited when the tem-
perature of Europe was nearly similar to what it is at present.
The proofs are the following : — The tertiary formations of this
age in Norway, Sweden, Denmark, St Hospice near Nice, and of
a part of Sicily, contain, in a fossil state, all the identical species
of the corresponding seas. These same formations of the Me-
diterranean side of France, of Spain and Piedmont, of Italy, of
Sicily, of the Morea, and pf Barbary (Algiers) contain a great por-
tion of the species which live in the Mediterranean, but contain
also some whose analogues no longer exist, or are distributed in
small quantity in the hot regions of the Atlantic Ocean and in
the Indian Seas. These observations have induced me to be-
lieve that the Mediterranean has experienced a slight depression
of temperature, since the chain of the Atlas on the one side, and
that of the Apennines on the other, assumed their present relief.
During the second tertiary epoch, to which belong a great num-
ber of small basins, scattered especially near the centre of Europe,
the temperature has been very different from that which at pre-
sent exists in these places. In fact, the species peculiar to
the Senegal and the sea of Guinea, those which best represent
the temperature of that part of the equatorial zone, are found
in the fossil state in the beds of this second period. The tem-
perature of the third period, at first a little more elevated than
our own in the Mediterranean basin, has become similar to that
which we experience ; in the north the species of the north are
fossil ; in the south the species of the south. Thus, since the
commencement of the tertiary formations, the temperature has
been constantly diminishing, passing in our climates from the

180 Scientific Intelligence — Hydrography.

equatorial to that of our own day ; it is easy to determine the
difference. Natural philosophers, by resting on their beautiful
theories of heat, have doubtless been able to suppose a priori
the changes of temperature of which I have spoken ; it is, never-
theless, curious to perceive their conjectures confirmed by a
science for a long time neglected, and which no one thought of
directing to this new object."*"

HYDROGRAPHY.

9. The Level of the Caspian much below that of the Ocean.^^
In 1814, Messrs Engelhardt and Parrot attempted to determine,
by means of the barometer, if, as was long ago supposed, the wa-
ters of the Caspian Sea are less elevated than those of the Medi-
terranean and the ocean. The mean of three determinations
gave a difference in this respect of 98 metres. But subsequently
M. Parrot having thrown some doubt on the result of these ob-
servations, made in 1814, M. Erman has taken up the subject,
and the following is the result of his investigations : Barometri-
cal observations made for seven years at Kasan, compared with
corresponding observations made during the same period at Dant-
zig, give 31.8 metres as the height of the former town above
the level of the Baltic. This result is confirmed by six years'
observations at Mitau. Hence, with the assistance of levelling,
M. Erman concludes that the height of the junction of the Ka-
sanka with the Volga, is only 8.8 metres above the Baltic.
Thus, in order that there should be a coincidence between the
levels of the Caspian and the Baltic, it would be necessary that,
in the extent of 205 German miles between Kasan and Astracan,
the descent of the river should not be more than 8.8 metres,
which seems inadmissible. The descent of the Volga from Tor-
jok to Kasan, in an extent of 155 miles, has been measured.
Supposing that, in the remainder of its course, the river follows
the same law, M. Erman has ascertained that the depression of
the Caspian Sea, compared with the Baltic, would be eighty-
four metres — a result which does not differ much from that
(ninety-eight metres) obtained by Messrs Engelhardt and Parrot.
10. Spring at the Summit of a Mountain. — M. Durieu, who
lately made a scientific journey in the kingdom of the Asturias,
mentions the following important fact in physical geography :^

Scientific Intelligence- — Botany. 181

* A beautiful spring flows from the highest point of the peak
of the Sarrantma ; but, as this peak is not commanded by any
neighbouring summit, we must necessarily suppose that the other
branch of the syphon must be placed at a great distance to the
east, to. receive, on the flanks of the mountains covered by per-
petual snow, and having a much greater elevation, the water
which issues from the extremity of the shorter branch, and which
an extraordinary accident or a concealed natural cause, has
forced to ascend to the top of a pointed peak.""

BOTANY.

11. Fossil Ferns. — The following general conclusions re-
garding the geological and geographical distribution of fossil
ferns, are contained in a recent memoir by Professor Goppert.
The beds of the coal formation contain the largest number of fossil
ferns, viz. 182, while the muschelkalk, and the chalk and tertiary
formations, contain the smallest number. The total number of
these fossil vegetables at present known amounts to 253, of
which ninety-two have been found in Silesia, twenty-nine m
Bohemia, fifty-six in the other countries of Germany, forty-nine
in France and Belgium, eighty-nine in Great Britain, three ill
Denmark and Sweden, one in Italy, eleven in North America,
one in Holland, and four in the East Indies. The ferns that
are the most widely distributed on the globe are the following : —
Alethopteris Serlii (in England, France, Silesia, Pennsylvania),
Neuropteris angustifolia and N, abutifolia (in England, Bohe-
mia, Silesia, Pennsylvania), and iV. Lohsii (in England, France,
Belgium, in the districts of the middle Rhine, in Bohemia, and
Silesia). Most of the ferns of the Jura formation occur in Eng-
land. The number of fossil ferns amounts nearly to a third of
the total number (800) of fossil vegetables at present known
But it is very probable that we are acquainted with but a small
portion of these fossils. Several genera of ferns belong exclu-
sively to one or to two formations. Thus, the following occur
only in the coal formation : — Gleicheniies, Balantitcs, Beinertia^
BocJcschia^ Danceites, Diplacites, Glockeria, Glossopteris, Stef-
Jensia^ Woodwardites ; and the same formation contains also the
most of the species of the genera Asplenites, Adiantites, Aspi-
dites, Alethopteris, Cheilauthites, Cyatheites, Hemitelites, Neu-
ropteris y OdontopteriSf TrichomaniteSy and IlymenophyUiteg

182 Scientific Intelligence — Anthropology,

The two genera Anomopteris and Scohpendrites are peculiar to
the gres bigarrL The genus Asterocarpus occurs in the coal
formation, and also in the Keuper, Pachypteris only in the Jura
series, and most of the species of Acrostichites and Polypodites
in the same formation. Fossil ferns of all formations, without
even excepting those of the chalk and the Molasse^ present a
striking resemblance to the tropical species of ferns, but none
to those of temperate and cold climates. One of the principal
conclusions to be drawn from the geological distribution of fossil
ferns is, that each formation has particular species, which differ
essentially from those of other formations. To this there are
very few exceptions. Silesia is remarkable for its extremely rich
fossil flora, for no less than 230 species have already been found
in that country. The fossil flora of England resembles greatly
that of Silesia. Excepting the genus Stigmaria, which is com-
mon to the transition and the coal formations, no species has
been found in two formations. Finally, it is remarkable that
dicotyledons and junci occur both in the most ancient and in
the most modern deposits, a fact which tends to prove that
there is little foundation for the opinion that at the earliest
epochs cellular plants only existed, afterwards monocotyledons,
and then at a later period dicotyledons.

ANTHROPOLOGY.

12. Prospects of the Negro Population in South America^
and of the gradual extinction of the original inhabitants of
the New World. — We behold (says the Foreign Quarterly) with
a conviction which no arguments can weaken, with a vivid-
ness of perception which no efforts of our own can soften, the
certainty of an impending and tremendous conflict between
the white and the negro, the coloured and the Indian popu-
lation, the fearful nature of which it is as easy to foresee as it
is awful to contemplate. Such is also the opinion of Dr Poep-
pig, who, in his account of Chili, has the following observa-
tions : — " No country in America enjoys, to such a degree
as Chili, the advantages which a state derives from an homo-
geneous population and the absence of castes. If this young
republic rose more speedily than any of the others from the
anarchy of the revolutionary struggle, and has attained a high
degree of civilisation and order, with a rapidity of which there

Scientific Intdligence — Anthropology. 183

is no other example in this continent, it is chiefly indebted for
these advantages to the circumstance, that there are extremely
icw people of colour among its citizens. Those various transi-
tions of one race into the other are here unknown, which stran-
gers find it so difficult to distinguish, and which, in countries
like Brazil, must lead, sooner or later, to a dreadful war of ex-
termination, and in Peru and Columbia will defer to a period
indefinitely remote the establishment of general civilisation.* * ♦
If it is a great evil for a state to have two very different races
of men for its citizens, the disorder becomes general, and the
most dangerous collisions ensue, when, by an unavoidable mix-
ture, races arise which belong to neither party, and in general
inherit all the vices of their parents, but very rarely any of their
virtues. If the population of Peru consisted of only Whites and
Indians, the situation of the country would be less hope-
less than it must now appear to every calm observer. Des-
tined as they seem by Nature herself, to exist on the earth
as a race, for a limited period only, the Indians, both in the
north and the south of this vast Continent, in spite of all the
measures which humanity dictates, are becoming extinct with
equal rapidity, and in a few centuries will leave to the whites
the undisputed possession of the country. With the Negroes
the case is different ; they have found in America a country
which is even more congenial to their nature than the land
of their origin, so that their numbers are almost everywhere
increasing in a manner calculated to excite the most serious
alarm. In the same proportion as they multiply, and the white
population is no longer recruited by frequent supplies from the
Spanish peninsula, the people of colour likewise become more
numerous. Hated by the dark mother, distrusted by the white
father, they look on the former with contempt, on the latter
with an aversion which circumstances only suppress, but which
is insuperable, as it is founded on a high degree of innate pride.
All measures suggested by experience and policy, if not to amal-
gamate the heterogeneous elements of the population, yet to or-
der them so that they might subsist together without collision,
and contribute in common to the preservation of the machine of
the state, have proved fruitless. * * * The late revolutions have
made no change in this respect. The hostility, the hatred, of the
many coloured classes will continue a constant check to the ad-

184 Scientific Intelligence — Anthropology,

vancement of the state, full of danger to the prosperity of the
individual citizens, and perhaps the ground of the extinction of
entire nations. The fate which must, sooner or later, befall
the greater part of tropical America which is filled with negro
slaves, which will deluge the fairest provinces of Brazil with
blood, and convert them into a desert, where the civilised white
men will never again be able to establish himself, may not indeed
afflict Peru and Columbia to the same extent ; but these coun-
tries will always suffer from the evils resulting from the presence
of an alien race. If such a country as the United States feels it-
self checked and impeded by its proportionably less predomi-
nant black population ; and if there, where the wisdom and power
of the government are supported by public spirit, remedial mea-
sures are sought in vain ; how much greater must be the evil in
countries like Peru, where the supine character of the whites
favours incessant revolutions, where the temporary rulers are not
distinguished either for prudence or real patriotism, and the in-
finitely rude Negro possesses only brutal strength, which makes
him doubly dangerous in such countries, where morality is at
so low an ebb. He and his half descendant, the mulatto, joined
the white Peruvian, to expel the Spaniards, but would soon turn
against their former allies, were they not at present kept back by
want of moral energy and education. But the Negro and the
man of colour, far more energetic than the white Creole, will in
time acquire knowledge, and a way of thinking that will place
them on a level with the whites, who do not advance in the samie
proportion so as to maintain their superiority.*" When we con-
sider all these circumstances, when we see Buenos Ayres even
now harassed by perpetual wars with the Indians, when we think
of the frightful crimes that have already taken place at Para, we
cannot but anticipate the consequences that must ensue if the
Negroes should rise in a general insurrection, and be joined by
the native Indians. We wonder at the blind infatuation of the
Brazilians, who, in defiance of their own laws, still import 100,000
new slaves every year from Africa, and we feel our minds de-
pressed by the melancholy persuasion, that the future fate of
these fine countries will prove even more tremendous than the
awful denunciation which threatens to visit the sins of the fathers
upon the children, even to the third and fourth generation.
13. Historical and Statistical Researches on the Causes of the

Scientific luldllgeuce — Aiitkrupulogy. 185

Plague. By M. de Segur Dupeyron. — M. de Segur Dupey-
ron had already attempted to prove that the plague comes to
Europe chiefly from Egypt. This proposition not having been
generally admitted, he has thought it necessary to develop fur-
ther this part of his researches. In examining the correspon-
dence of the consuls preserved in the archives of the I^oreign Office,
M. de Segur has found that two circumstances are indicated,
which, in certain cases, may produce the plague in Egypt.
These circumstances are, 1. Famine ; 2. Malignant Fevers. But
famine in Egypt is generally caused by the too great or too small
rise of the Nile. After a small inundation, little of the land
having been irrigated, but a small portion can be sown ; and
after a great overflow the waters require a long time to retire,
and the seed-time passes before all the grain has been deposited
in the earth. Hence M. de Segur has searched in Arabian
authors for information regarding the height attained by the
Nile, in the greatest possible number of overflowings, and he has
inquired if, in the years corresponding to the too small and too
great inundations, the plague has not existed somewhere. His
investigations have been limited to the period comprised between
the middle of the tenth century, and the middle of the fifteenth,
because the works which he has been able to consult, notice
only the inundations during that epoch. Of fifty to fifty-five
» plagues that have occurred in Europe during these five cen-
turies, forty coincide with the too great or loo small risings of
the Nile. As the great work on Egypt contains a table of the
heights of the river from 1737 to 1800, the author has been able
to ascertain if in that number of years the plague occurred in
the country after unfavourable inundations, and he has found
that of fourteen plagues which took place during the period,
thirteen coincide with the bad inundations which produce
famine. After an examination of the correspondence of the
consuls in Syria, and in the islands of the Archipelago, M.
de Segur endeavours to prove, 1. That the plague prevailed in
Syria and the Archipelago only after it had previously mani-
fested itself in Egypt ; 2. That the famine in Syria and the
Archipelago has been followed only by malignant fevers, and
never by the plague, unless when it existed in Egypt ; and he
concludes, that the famine in Syria and the islands of the Archi-

VOL. XXI. NO. XM. JUI.Y 1880. N

1S8 New Publications.

pelago may be regarded as the origin of the same maladies it
produces everywhere ; but that in Egypt it gives rise to results
which follow it in no other country, since it is almost always ac-
companied by the plague. In conclusion, M. de Segur remarks,
that in Egypt there is a particular cause which increases the
malignant fever, so as to give it all the characters of the plague,
and this cause exists only in that country.

NEW PUBLICATIONS.

1 * The Physical and Intellectual Constitution of Man consideredy
By Edward Meryon, F. R. C. S., &c. London : Smith, Elder.
& Company. 1836. 8vo, pp. 240.

This agreeably written and interesting little volume we recom-
mend to the particular notice of our readers.

2. A Geological Sketch of the Tertiary Formation in the Provinces
of Grenada and Murcia in Spain, S^c, By Brigadier Charles
SiLVERTOP. London : Longman & Rees, 8vo, pp. 236, with
plates.

Silvertop is one of that active and enterprising corps of military
officers who of late years have devoted their time to the advance-
ment of geology. Like Murchison, their geological chief, Silver-
top is not a mere museum or closet, or society geologist, but an in-
defatigable and successful labourer in the field, as is shewn by the
interesting work now before us, which we doubt not will be prized
by all true lovers of practical geology.

3. Ascent to the Summit of Mont Blanc in 1834. By Martin Barry,
M. D. F.R. S.E., Member of the Wernerian Society, &c. Black-
wood & Sons, Edinburgh, 8vo, pp. 119, with plates. 1836.

Of this successful ascent to the highest point of Europe some ac-
count has already appeared in this Journal ; but the volume before
us contains many valuable and interesting additional details, and also
a luminous history of the observations of all preceding travellers
wlio have reached or attempted to reach the summit of Mont Blanc.

4. The Earth ; its Physical Condition and most remarkable Pheno-
mena. By VV. M. HiGGiNS, F.G. S., Lecturer on Natural Phi-
losophy at Guy's Hospital. London : Orr & Smith. 1836.
12mo, pp. .512.

This amusing and generally correct view of the physical history
of our globe will take its place among the more esteemed of our
popular works on this subject.

TO COURESPONDENTvS.
Several papers received will be noticed or inserted in next number of this
Journal.

( 187 >

List of Pateiits granted in Scotland from \Sth March to \Qth

June 1836.

1. To Francis Brewin of the Kent Road, in the county of Surrey, Esq*
for " a certain new and improved process of tanning." — Sealed at Edinburgh
18th March 1836.

2. To James Morison of Paisley, North Britain, manufacturer, for " im-
provements on the jacguard machine, and on what is called the ten box lay,
and on the reading and stamping machines used in making shawls and other
figured work."-t.lOth March 183(>.

3. To Luke Herbert of Paternoster Row, in the city of London, civil-
engineer, for '•'' certain improvements in mills or machines for grinding and
sifting farinaceous and other substances." — 23d March 183G.

4. To John Brunton of West Bromwich, in the county of Stafford, en-
gineer, for "" certain improvements in the construction of retorts for generat-
ing gas for the purpose of illumination." — 25th March 1836.

6. To Miles Berry, of the office for Patents, 66 Chancery Lane, in the
county of Middlesex, civil-engineer and mechanical draftsman, for " a certain
improvement, or certain improvements, in the system, or mode, or method, of
working engines for exerting mechanical power," communicated by a fo-
reigner residing abroad — 6th April 1836.

6. To Joseph Chesseborough Dyer of Manchester, in the county of
Lancaster, machine-maker, and James Smith of Deanstone, in the county
of Perth, cotton- spinner, for *■' certain improvements in machinery used for
winding upon spools, bobbins, or barrels, slivers or rovings of cotton wool,
and other fibrous substances of the like nature." — 7th April 1836.

7- To William Hale of Greenwich, in the county of Kent, late of Col-
Chester, in the county of Essex, civil-engineer, for '* certain improvements
on machinery applicable to vessels propelled by steam or other power, which
improvements, or parts thereof, are applicable to other useful purposes.'' —
llth April 1836.

8. To John Birkby, late of High Town, but now of Upper Rawfolds
both of Liversedge near Leeds, in the county of York, card-maker, for " im-
provements in machinery for making needles." — llth April 1836.

9. To Frederick Chaplin of Bishop Storford. in the county of Herts,
tanner, for " an improvement in tanning hides and skins of certain descrip-
tions."— llth April 1836.

10. To Charles De Berguk of Clapham Rise, in the county of Surrey,
engineer, for " certain improvements in machinery used for spinning and
doubling yarn or thread, manufactured from cotton or other fibrous materiaL"
— llth April 1836.

11. To Frederick Edward Harvey of the Horsely Iron- works, in the
parish of Tipton, and county of Stafford, mechanical draftsman, and Jere-
miah Brown of Tipton, in the same county, roll-turner, for " certain im-
provements in the process and machinery for manufacturing metallic tubes,
and also in the process or machinery for forging and rolling metal for other
purposes." — 22d April 1836.

12. To William Maugham of Newport Street, Lambeth, in the county
of Surrey, chemist, for " certain improvements in the production of chloride
of lime, and certain other chemical substances." — 25th April 1836.

13. To Thomas RiDGWAY Bridson of Great Bolton, in the county of
Lancaster, bleacher, for " a certain improvement or improvements to facili*
tate and expedite the bleaching of cotton, linens, and other vegetable fibres."
--25th Aj.ril 1836.

14. To Joseph Lidel of Arundel Street, Panton Square, in the county
of Middlesex, Professor of Music, for " certain improvements in piano fortes,''
communicated by a foreigner residing abroad — 28th April 1836.

188 List qf'Scottuh Patthts.

15. To Andrew Smith of Princess Street, in the parish of St Martm in
the Fields, and county of Middlesex, engineer, for " certain improvements in
engines for exerting power for driving machinery, and for raising and lower-
ing heavy bodies."— 28th April 1836.

16. To John Burn Smith of Salford, in the county of Ijancaster, cotton-
spinner, and John Smith of Halifax, in the county of York, dyer, for " a
certain method or methods of tentering, stretching, or keeping out cloth to
its width, made either of cotton, silk, wool, or of any other fibrous substances,
by machinery." — 28th April 1836.

17. To Robert Copland of Brunswick Crescent, Caniberwell, in the
county of Surrey, Esq., for " improvements upon patents already obtained
by him for combinations of apparatus for gaining power." — 6th May 1836.

18. To William Preston of Sunnyside, in the county of Lancaster, ope-
rative calico-printer, for " certain improvements in printing of calico and
other fabrics."— 10th May 1836.

19. To Henry Sharpe of Broad Street Buildings, in the city of London,
merchant, for " improvements in sawing wood and other materials," commu-
nicated by a foreigner residing abroad. — 10th May 1836.

20. To James Cropper of the town and county of the town of Notting-
ham, lace manufacturer, and Thomas Brown Milnes, of Lenton Works, in
the county of Nottingham, bleacher, for " certain improvements in machi-
nery or apparatus for embroidering or ornamenting bobbin-nett, or lace or
cloths, stuiF, or other fabrics made from silk, cotton, wool, flax, or hemp,'*
communicated by a foreigner residing abroad, and improvements made by
themselves 10th May 1836.

21. To Jacob Perkins of Fleet Street, in the city of London, engineer,
for " improvements in the apparatus and means for producing ice, and in cool-
ing fluids."— 13th May 1836.

22. To William Gossage of Stock Prior, in the county of Worcester,
chemist, and Edward White Benson of Wichbold, in the same county,
chemist, for " an improvement or improvements in the process of making or
manufacturing ceruse or white lead." — 20th Ma}'^ 1 836.

23. To Henry Adcock of Summer Hill Terrace, Birmingham, in the
county of Warwick, civil-engineer, for " certain improvements in the loading
and unloading of ships, brigs, schooners, and other vessels, at docks and quays,
and in streams and rivers, and for the more facile transit and stowing of mer-
chandize taken from ships, brigs, schooners, and other vessels at docks and
quays, with a view to abridge human labour and economise expenses — 24th
May 1836.

24. To John Whiting of Rodney Buildings Row, Kent Road, in the
county of Surrey, Doctor of Medicine, for " an improvement or improve-
ments in preparing certain farinaceous foods." — 24th May 1836.

25. To Samuel Draper of Basford, in the county of Nottingham, lace-
maker, for " improvements in producing plain or ornamental weavings." —
24th May 1836.

26. To George, Marquis of Tweeddale, for " an improved method of
making tiles for draining, soles, house-tiles, and flat roofing tiles." — 25th
May 1 836.

27. To Thomas Grahame of Nantes, in the Kingdom of France, but now
of Suffolk Place, Pall Mall, in the county of Middlesex, gentleman, for " cer-
tain improvements in passing boats and other bodies from one level to ano-
ther."— 26th May 1836.

28. To Jeremiah Horsfall and James Kenyon, both of Addingham,
in the county of York, cotton spinners, for " certain improvements in engines
used for carding cotton, wool, and other fibrous substances."— 13th June 1 836.

29. To Francis Pettit Smith of Hendon, in the county of Middlesex,
farmer, " for an improved propeller for steam and other vessels." — 15th June
1836.

30. To George Holworthy Palmer, of the Canal Grove, Old Kent
Road, civil-engineer, for " an improvement in the purification of inflamma-
ble gases, and an apparatus by which the improvement is applied, such appa-
ratus being also applicable to other useful purposes."— 16th June 1836.

THE

EDINBURGH NEW
PHILOSOPHICAL JOURNAL.

On Volcanos and Craters of Elevation. By Leopold Von

Bitch.

The tour which I made in the autumn of 1834, with Pro-
fessor Link and M. Elie de Beamnont, and afterwards also with
M. Dufrenoy, enabled us to determine more exactly some of
those relations of elevation-craters, of which T formerly treated
in the Academy, seventeen years ago, and also in my work on
the Canary Islands.

Volcanos are the constant chimneys, the canals uniting the in-
terior of the earth with the atmosphere, which spread around
themselves the phenomena of eruption from craters that are of
small extent, and are only once in operation. Craters of eleva-
tion, on the contrary, are the remains of a great display of
power from within, which can and actually has raised islands of
several square miles in extent, to a considerable height. They are
conical and very extensive circular enclosures (umgebungen), with
strata, which internally seem horizontal, but which on all sides
dip to the exterior in a mantle-shaped manner. From such en-
closures proceed no eruptive phenomena, there is no canal con-
necting them with the interior, and it is only rarely that we find
in the vicinity or in the interior of such a crater traces of vol-
canic activity still in operation. This difference seems to me
more an observation than a hypothesis. It is the separation of

VOL. XXI. NO. XLII.— OCTOBER 1836. O

190 M. Von Buch on Volcanos and Craters of Elevation.

appearances whose causes cannot be ascertained, or even investi-
gated without such a distinction.

That from the middle of such an elevation-crater, whose ac-
tion was only for a short period of time, a new cone should arise,
generally of trachyte, which becomes a permanent volcano, and
spreads its eruptive phenomena over a wide circle around it, is
strikingly and pre-eminently exemplified by the Peak of Tene-
riffe.

But, as in many other volcanos, melted substances which flow
in the form of streams of lava, are raised to the edge of the vol-
canic crater; it has been supposed to be a fundamental truth,
that a mountain of this description must have been produced by
means of such a rising up, and the subsequent hardening of the
flowing lava ; that thus, Vesuvius, even Etna, and many simi-
lar mountains, have gradually been raised from a low level to
their present height ; and the certainty that volcanic cones must
have attained their present elevation by this process, has led
some geologists to suppose and assert a similar gradual increase
of height in the case of the enclosures of craters of elevation ; al-
though streams of lava never occur in elevation craters. Our

o

journey has afforded us complete proof, that a volcanic cone can
never be produced by the continued building up of streams of
lava^ that its height can be increased only by the sudden eleva-
tion of solid masses, and that the whole cones of Etna, Vesuvius,
Volcano, and Stromboli, owe their first elevation to a sudden
projection above the surface.

We have to thank the unceasing activity in observing of M.
Elie de Beaumont, for the chief proof of this important fact,
a proof which I may term truly striking, inasmuch as it direct-
ly seizes hold of the subject, and leaves so few difficulties un-
explained. He has ascertained by the careful measurement of
about thirty streams round Etna, and of a great many on
Vesuvius, that a stream having an inclination of 0^ or more can-
not possibly form a continuous mass; it falls so rapidly that it
can acquire only an inconsiderable thickness — not amounting
to more than a few feet. It is only when the inclination is
not more than 3% that the mass can spread, and can accu-
mulate to a considerable height. Now as the last third of
Etna rises with an inclination of W to 3^% it is clear, that

M. Von Buch on Volcanos and Craters of Elevatmi, 101

when even a stream of lava flows from the great crater, which
very rarely happens, it can produce very little effect either as
to the increase or the external form of the mass. Even at
the bottom of the Val di Bove, which is a great subsidence on
the declivity of the volcano, the inclination of the streams is
still 8° or 9°f and hence their thickness is so inconsiderable
that their course is recognised by their black colour, and not by
their bank-like continuation. The form also of Etna is quite
regular, rising up on all sides with a uniformly advancing out-
line. The many, almost innumerable cones of eruption of the
declivity and round the base, stand like warts on the vast
colossus ; and the streams which flow from it so completely dis-
appear at a short distance, that we must necessarily regard it as
an absurdity to ascribe to them even the slightest influence in
altering the form of the mountain.

A few of Beaumont's determinations may shew the truth of
the conclusion drawn : The great stream of lava which in 1669
destroyed many villages, and flowed past the walls of Catania to
the sea, burst forth at the foot of the Monti Rossi, with an in-
clination of 2° 58', and so proceeded eastwards from Monte Pilieri.
There, where the road from Nicolosi to Torre di Grifo crosses
this stream, its medium inclination up towards its source is 3° 45',
and down towards the sea 2° S^'. Near Catania, where the
breadth of the stream is much less considerable, its inclination
is 5" or 6°, but soon diminishes towards the sea. The medium
inclination of this rapid stream is therefore only from 2° to 3°.
The lower part of the stream of lava which in 1832 threatened
Bronte, has an inclination of 1° 51', and still presents to the eye
a very distinct slope. The slightly elevated streams which de-
scend very rapidly from the woods at Zafl*arana have a medium
inclination of 6° 23'. From the base towards Aci Reale where
they form high banks, their inclination is 2° 13'. The highly
inclined and broken up streams of lava between Randazza and
Lingua grossa vary from 4° to 4^°.

A stream which descends from the Piano ArenosOy under the
summit of Etna, to the steep Val di Bove, has an inclination of
24°, but then it has only marked its course by a narrow line of
very loosely cohering slag, like all other streams which descend
from a similar height, with so great an inclination.

o2

19^ M. VoH Buch on Volcanos and Craters qf Elevation,

The same is the case on Vesuvius. The broad stream of lava
which is crossed before the Hermit'*s Hill is reached, descends
with an inclination of 3°. The streams of 1804 and 1822, which
pass the hill of Camaldoli, from the Torre del Annunziata, have
an angle of not quite 4°. The last cone of Vesuvius, on the
contrary, rises with an inclination of 28° to 30°. Very frequent-
ly, much more so than in other volcanos, streams flow down this
steep declivity. We look out for them, in order to ascend on
their surface to the summit. But we never see them of great
extent ; they hardly ever have a greater thickness than four feet,
and at the edge of the crater their mass is like a ray on the
slope. They pierce for themselves rapidly a deep and narrow
furrow in the loose materials, and cannot extend at all in breadth.
On the 12th August 1805, Humboldt, Gay-Lussac, and my-
self witnessed this phenomenon. We were standing at 9 o'clock
in the evening on the balcony of a window in sight of Vesuvius.
Suddenly a line of fire shot like lightning from the summit to
the base, and remained fixed on the mountain like a burning
thread. We proceeded rapidly in a boat to Torre del Greco ;
but the stream had already obstructed the great road. After
such a sight, and after the experiments mentioned, we require
no further arguments to convince us that mantle-shaped masses,
or masses spreading out over a considerable space, cannot be
streams of lava which have flowed on steep declivities ; and the
observations of M. Elie de Beaumont give certainty to this
conclusion.

Even though the beds of which Vesuvius, Somma, Etna, and
Stromboli are composed, were sent from the interior of the earth
in a liquid state, yet they cannot have been originally formed in
the condition in which we now find them, viz. as the surround-
ing masses of a steep cone ; but must have acquired their present
form from a cause acting on themselves, viz. the elevation round
an axis, which axis was opened up in the form of a crater after
the elevation.

It is indeed very remarkable and striking, that this was not
observed at the first glance of the Vesuvius of our day. Hamil-
ton, it is true (Campi Fhlegrei, p. 63), makes the very well
founded remark, that probably this volcano may have been first
formed at the time of the earliest of all known eruptions; that

M. Von Buch on Volcarios and Craters of Elevation. 193

which destroyed Herculaneum and Pompeii ; for the very accu-
rate Strabo gives a description of the mountain, which does not
nt all correspond with its present form, or with that it presented
at the time of any of the eruptions. He says : dempto vertice,
qui magna sui parte planus, totus sterilis est. Geog. lib. v, — a
mode of expression which cannot apply to a steep and sharp
cone like our Vesuvius.

of the TifJUk

VemviuSf or Somma, according to Strabo.

Strabo would certainly not have omitted to mention the double
hill ; Spartacus would not have pitched a camp for ten thousand
gladiators in the small crater of the steep Vesuvius ; Pliny would
not have forgotten to enumerate in his list of volcanos a moun-
tain so like Stromboli as the present cone of Vesuvius, if it had
been in existence.

Stnnma and Vesuvius after ike time of Pliny,

Hamilton, however, was of opinion, that this cone had been
gradually produced by the continued eruptions of ashes and lavas.
Its height has, on the contrary, been constantly decreasing, and
will go on diminishing. It is extremely probable that Vesuvius
has become a true volcano by this elevation in the interior of the
crater of Somma, or in the interior of Strabo^s Vesuvius ; or that
it is only since that time that a permanent communication has been
opened with the atmosphere : for the Somma itself possesses so
perfectly all the characters of a crater of elevation, that we may

194 M. Von Buch on Volcafios and Craters of Elevation.

regard it as a model of this volcanic form, and nothing is visible
in this mountain which indicates a resemblance to a real volcano,
or which is similar to a real stream of lava. Not only are the
beds of leucitophyre, of which it consists, spread over a great
part of the circumference, as we now see it, but they are inclined
to the exterior, with angles varying from 20° to 30°, without
any diminution of their often considerable magnitude — a state
of things completely at variance with the phenomena presented
by streams of lava having so high an inclination. But the ele-
vation of the whole of the vast mountain, in its full extent, is
proved in a still more striking manner by the mode in which the
Neapolitan tufFa is disposed round the declivities. The tuffa is
a white porous rock, composed chiefly of pumice, and extends
over the whole plain between the Apennines and the sea. It is
found from Capua to the hills of Sorrento, from Nola to be-
yond Naples, and almost always in horizontal strata, reposing
immediately one above another, and thus the surface is perfectly
level. These white strata approach the Somma without inter-
ruption, but when they reach its base they immediately ascend,
and follow the inclination of the acclivity, at a high angle. At
a certain height, which remains perfectly the same round the
mountain, they stop, and then we observe, rising with a high
inclination, the black leucitophyre beds of the walls of Somma,
which continue to the summit. The boundary of the tuffa
round the mountain is rendered distinctly visible from a distance
by the little platform which results from this slight difference
of inclination between the beds of tuffa and of leucitophyre ;
and indeed these relations which are of such high importance for
the history of the whole, are beautifully exhibited, and in a man-
ner as clear as it is picturesque, in the superb view of the vol-
cano, and its neighbourhood, obtained from the town of Naples.*
The height to which the tuffa ascends is about 1900 feet above
the sea, both on the acclivity on the Somma and Ottajano side,
and on that above Pompeii and Torre del Greco. Its limit is
the long hill on which the well known house of the hermit is
built. The upper part of the Somma, that without tuffa, rises

• The boundary of the tuffa is well marked in the two cuts on the pre-
ceding page.

M. Von Buch on Volcanos and Craters of Elevation. 195

1500 feet higher. In the whole plain of Naples the horizontal
strata of tufFa rise only at one point to the height of 1419 feet,
near Camaldoli of Pouzzoli, and there only for a very limited
space. Their usual height in the plain never exceeds 800 feet
above the sea, and that is not half the height to which they
are elevated on the Somma. At the volcano, therefore, they
are no longer in their original position, but have actually been
elevated round an axis, which is the axis of the crater itself.

It is not generally stated, that the strata of white pumice-tufFa
surround not only the side of the mountain towards the Apen-
nines, or towards S. Anastasia, Somma, and Ottajano ; but also
all the part towards the sea ; and it may escape many observers,
that the Hermit's Hill, which is cut through by the path^ be-
longs to the general covering of the plain of Naples, and not at
all to the rocks of Vesuvius. It is easy to be convinced of this
being the fact, by examining the direct connection which subsists
between the mass composing the little eminence, and the lower
strata at the base of the mountain. It is equally certain, that
similar strata appear in the ravines above Torre del Greco, and
that the products which occur at the foot of the hill of Camal-
doli of Annunziata, are to be included under the same head. As
Professor Link and myself descended on the 21st of October
1834, from the Lava which had burst out on the 8th August
to Bosco trc Case, we saw also, on that side, considerable strata
of white tuffa, almost directly above Pompeii. Hence it seemed
evident, that it must have been from such strata that the. frag-
ments of pumice which cover Pompeii were separated, and
which, hitherto so inexplicable, there lie mixed with Vesuvi^n
leucitophyre. Leucitic rocks are not found in connection with
pumice. The latter is a product of the conversion of trachyte
into obsidian. But both these are substances which never oc-
cur in Vesuvius ; and the volcano has never been known to
throw out the smallest fragment of pumice. Hence the pu-
mice of Pompeii remained an enigma. If, however, as is now
nearly certain, it has been torn from such strata, similar to those
existing above Bosco tre Case, it becomes extremely probable
that Vesuvius, when it rose from the middle of the crater of
Somma as a permanent volcano, projected around on the side
towards the sea, not only the upper portion of the surrounding

196 M. Von Buch on Volcanos and Craters of Elevation.

Somma, but also a considerable mass of the upper strata of
tuffa, in order to open a place for its own beds ; and then by
these appearances, Strabo"'s description will be confirmed as per-
fectly consonant with truth, and will be recognised as a most
important document in the history of volcanos in general.

The Neapolitan puraice-tuffa is not a direct product of vol-
canic eruption, but is a tertiary formation as much as the lime-
stone of Syracuse and Palermo. It has been formed in the sea
and distributed by the sea with regularity over the surface.
This has not been doubted since the time of Hamilton ; but it
is too often forgotten when separate eruptive phenomena of the
Neapolitan district are described, and when the origin of the
tuffa is ascribed to such particular eruptions. But there is al-
most no district that is connected by this tuffa, in which marine
productions do not occur in the strata; and these occur of
such beauty and perfection, and with such completely preserved
shells, that we might think it impossible that they had ever been
at any period, exposed to the violent movements of volcanic ac-
tion. The Neapolitan collections, especially those of the Aca-
demy, of Monticelli, and of Dr Leopold Pilla, contain excellent
specimens of this description from various localities ; and others
from many different places, we find figured but indifferently in
Hamilton's work. Among the last there is in Plate xlv. a large
beautiful oyster included in the tuffa, from a quarry at Baiae,
Dr Pilla has a similar oyster contained in the tuffa of Posilipo,
from where the new road is cut through the hill. Hamilton
has figured a whole collection of a Cerithium, probably the Ce-
rithium vulgatum, found in a quarry at the summit of Posi-
lipo, and similar to the species which occurs so frequently in
Ischia, and at the Faro of Messina. The 47th plate is en-
tirely a representation of such a Cerithium conglomerate, which
was found in the Fossa Grande, under the Hermit's Hill, near
the Somma, and which is so well known as a rich locality for
minerals. Fig. 6. of Plate xlii. of Hamilton's work represents a
group of shells of a Pectunculus, from a tuffa quarry under
Capo di Monte ; and Monticelli has a similar pectunculus from
the Somma in his collection. Dr Pilla has discovered a small
Echinoneus, in considerable quantity, in the tuffa above the vil-
lage of Somma. which is very similar to the Echinoneus sub-

M. Von Buch on Volcanos and Craters of Elevation. 197

globosus, figured by Goldfuss, Plate xlii. fig. 9, which I have
also found in limesione near Syracuse. The Cardium edule from
the Somma is also to be seen in the collection of Dr Pilla.
These facts seem quite sufficient to prove, that all strata of tufFa
are not thrown out directly from a volcano, but that they are a
marine formation^ similar to the tertiary limestone, and that, on
that account, they are equally distributed over the whole sur-
face.

Since the Somma pierces through and elevates the strata of
tufFa, it cannot, of course, have existed as a mountain previously
to the formation of the tufFa. Still volcanic activity was not
on that account entirely without perceptible operations in this
district. It is remarkable, and in the highest degree worthy of
attention, that the tufFa of the Hermit's Hill, and also the strata
in the valleys called the Fossa Grande and the Fossa della Ve-
trana, contain between the fragments of pumice many blocks
and pieces of leucitophyre. In the tufFa of Naples there are
no traces of that substance. It would be important to know at
what distance from the mountain the leucitophyre is no more
found, but such investigations have never been undertaken.
These pieces must therefore belong to the strata which were at
first spread over the submarine surface by volcanic agency, and
which were at a later period raised up as walls of the crater of
elevation. But, associated with them, and also surrounded by
and included in the tuffk, we find masses of dolomite and other
rocks of older formation, which contain the greater number of
those beautiful crystals, by which Vesuvius has become more
celebrated among collectors of minerals than any other moun-
tain in the world. It has been calculated, that of all the mi-
neral species known, more than the half occur on the declivities
of Vesuvius, and that by much the greater number of these be-
' long to the fragments met with in the tufFa. They are gene-
rally termed the ejected masses of Vesuvius; and though we
have no examples of such masses having been thrown out from
the volcano, yet it has been imagined that they have been so at
an earlier period. It becomes quite evident how erroncH)us,
nay how completely absurd this opinion is, when wc reflect that
the including tufFa is identical in its formation with that of Ca-
pua and Naples, and that it was spread around previous to the

198 M. Von Bucb on Volcanos and Craters of Elevation.

elevation of the Somma. The included masses must therefore
have been in this district before the Somma, and much less Ve-
suvius, existed. They therefore cannot be ejected masses of
Vesuvius, or even of the Somma. Most probably they are the
products of a submarine deeply-seated volcanic action ; and as
an argument in favour of this opinion, we have the great analogy
which subsists between the substances now under consideration,
and the crystals which have been produced by the action of pri-
mitive rocks, that have been sent from beneath, on limestone,
and the contact edges of both rocks, as for example at Monte
Monzoni, in the valley of Fassa, in the valley of Ala in Pied-
mont, and also at Arendal in Norway. At all these localities a
great many of the Vesuvian minerals occur, and in part of equal
beauty, viz. vesuvians, garnets, epidote, unattached crystals of
augite, and others. It is only numerous species of the zeolite
family that are peculiar to Vesuvius. These have been formed
at a later period than the first mentioned minerals, and it would
seem under very different circumstances ; meionite, nepheline,
and sodalite, frequently cover vesuvian, crystals of hornblende,
and garnets, but are never covered or enveloped by these mi-
nerals.

Should appearances so varied and so intimately connected to-
gether not be sufficient to prove the elevation of the Somma
through the strata of tuffa, and the elevation of Vesuvius in the
middle of the crater of the Somma, still more decided evidence
is to be found in the neighbourhood of Naples, a district so rich
in important volcanic phenomena ; evidence which seems to place
the question beyond all doubt. Thus the elevation of such strata
of tuffa with a crater actually occurred before our eyes. The
Monte Nuovo near Pozzuoli, formed on the 19th September
1538, is a true crater of elevation, and by no means an erupted
hill. The disintegrated strata of tuffa in the middle, and the
blocks, ashes, and dust scattered around by the gases of the
interior, by which Pozzuoli itself was nearly entirely buried,
and every thing involved in darkness ; might well lead the con-
temporaneous observers to the conclusion that the mountain itself
had been produced by these ejected masses; and so much the
more, because its surface was seen covered by them. But the
aspect of the crater teaches us quite a different view of the sub-

M. Von Buch on Volcanos and Craters of Elevation, 199

ject. When, on the 11th October 1834, the distinguished
French geologists Elie de Beaumont and Dufrenoy, and my-
self, made the circuit of the crater, and descended into its in-
terior, we saw, with the greatest distinctness, on the declivities,
the terminations of the strata, whose component rock could
hardly be distinguished from the ordinary tufFa of Posihpo.
The inclination of the strata is to the exterior all around, as
may be easily observed. In the interior of the crater, and on
its bottom there are black slags in large masses ; and on the
outer surface the external covering is formed by large scattered
porous blocks of altered trachyte and other similar fragments.
Had the internal walls of the mountain been formed of ejected
masses, they would not be white, fine-grained, and compact,
but would only resemble shapeless conglomerates, composed of
extremely large and earthy fragments, to which they have no
similarity whatever.

Not long afterwards, we ascended the crater of Astruni,
one of the largest, and probably also the most beautiful, of all
the craters in the Phlegrean fields. The rock, which makes its
appearance on the interior declivities, is by.no means black and
slaggy, as we might expect it to be in such a crater 5 on the
contrary, it is rather striking from its great whiteness. Slags
lie in it as at Posilipo. It is composed of the strata of tufFa,
which are inclined round the axis to the exterior, and which are
well seen in Hamilton's representation, plate 20. This crater is
not level at the bottom, like Monte Nuovo, but presents in its
centre several hills, which rise to a height of 200 feet, and unite to
form a dome-shaped whole. These hills are composed oHrachyte.
The rock is not a lava, for we can nowhere observe the slight-
est trace of a stream. The mass also is every where continuous
and compact, being composed of large rocky portions, which are
separated only by clefts into large blocks. The trachyte con-
sists of a grey, coarsely splintery, much shattered basis, in which
are imbedded numerous and often considerable crystals of glassy
felspar, and in smaller quantity, black, small crystals, resembling
augite. The whole rock is like what we would expect to find
in a hill in the Siebcngehirge. How beautifully does not this
phenomenon explain the whole cause or history of the volcanic
operations ! In Mo9ite Nuovo we have a mountain with a era-

200 M. Von Buch an Vokanos and Craters of Elevation.

ter of elevation in its centre, but without a solid nucleus. In
the crater of Astruni, the compact masses rise up in a dome-like
form ; but they are not broken up — no lasting communication
with the interior, in short, no volcano is produced. These masses
remain, as it were, a model of the great trachytic unopened
domes, which are so numerously scattered over the surface of
the globe, and of which we have examples in the Pui/ de Dome
and Chimborazo. Vesuvius^ finally, does not rise up alone, but
exhibits also the required permanent communication which we
see opened at its summit, and thus affords an example of a true
volcano. It is probable that even the spectacle, and the oppor-
tunity of investigating so extraordinary a series of events, will
in a short time be presented to us. In the beautiful and exten-
sive elevation-crater of Santorin, which is composed of strata of
tuffa, trachytic masses have been raised up as in Astruni, but
only in detached and but slightly-continuous rocks. The bot-
tom of the crater has, near the land, a depth exceeding 600 feet.
For a series of years this bottom has been rising gradually from
the middle of the crater. The depth of the sea is constantly di-
minishing, and at the present time, the raised up land is very
near the surface. We have here evidently an example of a tra-
chytic dome, which will probably rise much higher than the sur-
rounding edges of the island ; and it is quite possible, nay, ex-
tremely likely, when we remember the violent movements to
which the northern part of the Morea is exposed, that the moun-
tain which is now being elevated will at length break out, and
form a volcano. M. Virlet was the first to make known this un-
expected and remarkable fact,* and it is too instructive and im-
portant to allow us to pass it over without quoting the words of
the author. The island, says Virlet, is rising between Micro-
Kameni and the haven of Thira in Santorin. Twenty years
ago, it was fifteen yards under the surface of the sea; in 1830,
Colonel Bory and M. Virlet found that the depth was only from
three and a half to four yards. Since that time, the depth has
been so much diminished, according to the public journals, that
the appearance of the island may be speedily expected. Its sum-
mit extends 2400 feet from east to west, and 1500 feet from

' Bulletin de la Soc. Geol. de France, iii. p. 1 09 ; and Edin. New Phil.
Journal, vol. xxi. p. 175. '

M. Von Buch on Volcanos and Craters of Elevation, 201

north to south. The slope sinks rapidly, and at a short distance
the depth is very great. The island is rising, says Virlet, like
a vast graft out of the sea.

Thus islands of elevation and craters of elevation are quite
a general consequence of volcanic activity ; but they are not
volcanos, though, nevertheless, as it would seem, they exercise
a much more important influence than the largest volcanos on
the alteration, and especially on the increase, of the surface of
the earth. Such islands are doubtless still rising from the sea.
It has been frequently conjectured, that all coral islands of the
South Sea which contain a shallow lake (lagune) in the middle,
may be regarded as islands of elevation ; and a new and extreme-
ly remarkable account given by Poeppig in the excellent and ta-
lented narrative of his journey, presents us with an example in
which Nature seems, as it were, to have been surprized in the
very act of forming such an island.

Captain Thayer, of the American schooner Yankee, visited
the haven of Talcahuano in Southern Chili. Poeppig saw him
there, and obtained permission to examine his journals. It ap-
peared from this authentic source, and from the relation of the
Captain, that, on the 6th September 1825, in south latitude
30° 14)', and east longitude 178° 15' from Greenwich, an entirely
unknown small island was descried from the ship. A thick
smoke rose from the middle of the island. Boats were sent to
examine it. As they approached a completely barren rock was
seen, which rose only a few feet above the surface of the sea.
It consisted of a broad ring which included a small pond, and
which, being broken at one point, seemed to admit the sea.
The sailors sprang out into the water in order to drag the boat
over the shallow, but in an instant they sprang back in the
highest degree alarmed, because the hot water had burnt their
feet. The smoke was seen to issue from several fissures which
traversed the surrounding ring. Only at one point sand was
found ; all the rest consisted of solid rock. The crater had a
diameter of 800 paces, and sloped so rapidly externally that at
a distance of 100 fathoms no bottom could be reached. Never-
theless, at a distance of four English miles the temperature of
the sea water was 10° to 15° higher than had previously been
remarked in these latitudes. This is the first time that one of

S02 M. Von Buch on Volcanos and Craters of Elevation.

the flat South Sea islands containing a sea lake has been seen
smoking and giving out vapour ; and it is not extraordinary, for,
as such a phenomenon only indicates violent volcanic action, and
not the existence of a volcano, the effects of the agency of the
fire disappear after a short time, and can only be seen by those
whom accident has conducted at so transient a moment to such
an inland. The solid masses of which it was composed were
widely different from those of Ferdinand's island (Graham's
island) off Sicily, or of Sabrina, near St Miguel in the Azores,
whose solid nucleus did not reach the surface, and whose loose
layers of erupted slags and lapilli were speedily destroyed by
the sea. In a few years corals surround such South Sea islands
as the one we have instanced, they become a resting place for
fatigued birds, and are gradually covered by vegetation.

We may therefore feel assured that discoveries in the great
ocean will never be exhausted. Islands will continue to rise
from the depths of the seas, and the various conditions of their
vegetation will relate their histories.

That elevation craters rise out of the sea is, however, quite
accidental, and does not belong to their internal constitution, or
to the conditions of 'their appearance. These relate chiefly to
the great restraining covering, which obstructs the extrication of
the imprisoned vapours from the interior, and which must there-
fore be removed and broken up before the vapours can escape
into the atmosphere. Hence craters of elevation can, in like
manner, be formed on the solid land, or, on already existing and
raised up islands, and of these we have examples, sometimes of
the gi'eatest distinctness, in almost every land. The Laacher-See
near the Rhine, Cantal, and Montdor, are among the most re-
markable