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JOURNAL OF SCIENCE,

CONDUCTED BY

DAVID BREWSTER, LL.D.

F. R. s. LOND. AND EDIN. F. Ss. s. A. M. R. I. A.

CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE; HONORARY MEMBER OF THE IMPERIAL
ACADEMY OF SCIENCES OF ST PETERSBURG; CORRESPONDING MEMBER OF THE ROYAL
PRUSSIAN ACADEMY OF SCIENCES; MEMBER OF THE ROYAL SWEDISH ACADEMY
OF SCIENCES; OF THE ROYAL SOCIETY OF SCIENCES OF DENMARK 3
OF THE ROYAL SOCIETY OF GOTTINGEN, &c. &c.

VORA:
NEW SERIES.

APRIL—OCTOBER. f:
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THOMAS CLARK, EDINBURGH:

T. CADELL, LONDON.
AND MILLIKIN & SON, DUBLIN.

M.DCCC.XXXI.

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“ HALOT

CONTENTS

OF THE

EDINBURGH JOURNAL OF SCIENCE,
No. IX.

NEW SERIES.

‘ArT. [. Observations on the Decline of Science in England, ‘ l
II. Observations respecting Professor Leslie’s Formula for the Decrease
of Heat in the Atmosphere ; and his Opinions respecting the Polar
Temperature. By James D. Forses, Esq. F. R.S. Ed. Com-

municated by the Author. : 17
111. Observations on the Meteor called the pct Boneiba. with Calcula-
tions, Trigonometrical and Analytical, towards determining the po-
sition and tne course of the Arches, with respect to the surface of
the Earth, By R. PorTrer, Esq. Junior. Communicated by the

Author, 3 ° é 23
IV. On the Respiratory Organs and Air-Bladder of certain Fishes of the
Ganges. By J. TayLor, Esq. : . 33

V. On the Question of the Existence of the Rein-Deer, ating the Twelfth
Century, in Caithness, By S. Hippeet, M.D. F. 3 S. Ed. &c.

&c. Communicated by the Author, ‘ 50
VI. On Monochromatic Light, and on the Achromatism and Spherical

Aberration of Eye-pieces and Engyscopes. By CHARLEs GORING. ‘

M.D. Communicated by the Author, ‘ 52

VII. On the Specific Heats of some of the Metals, with an Senatticea of

some erroneous Determinations by MM. Dulong and Petit; and

an examination, as to the Metals, of the important law, that the

ultimate particles of simple bodies have all the same capacity for

Caloric. By R. mice Esq. Junior. Communicated by the
Author, , $ i 75

VIIi. Observations on a new mode of constructing Harboiah By WIit-.
- L1aM MaTuHeEson, Civil-Engineer. Communicated by the Author, 83

IX. On the [ntensity of Light when the vibrations are elliptical. By

JAMES MACCULLAGH, Esq. Communicated by the Author, 86
X. Extraordinary facts relating to the Vision of Colours: with Observa-
tions. By Mr Joun Datton, - 88

X{. On the relation between the Refractive Posh and the polattniniy
angles of singly refractive substances. By Dr A. SEEBECK, 99

ii

XII.

XIIL.

CONTENTS.)

Abstract of Meteorological Observations made in the Isle of Man from
1822 to 1831. By Ropert STEWaRT, Esq. Receiver-General
of the Isle of Man. Communicated by Dr HIBBERT, :

Account of an Excursion from Lima to Pasco. In a Letter from
ALEXANDER CRUCKSHANKS, Esq. to Dr HOOKER, .

XIV. Account of the Russian Steppes, with Geognostical Observations made

XV.

XXIII.

in a Journey to the Environs of Mont Elbrouz, in the Caucasus,
undertaken in 1829 by order of the Emperor of Russia. By M.

Kuprrer of the Imperial Academy of Sciences, ‘
Historical Notice respecting the Inflammation of Phosphorus in Va-
cuo. In a Letter to the Editor by Professor Mott, re

. Remarks on Dr Goring’s Observations on the use of Monochromatic

Light with the Microscope. ‘

. Notice of the Discovery of the Tetidination of the Niger in the

Bight of Biafra,

. On the Diamond Mines of [Patina in. Bundelkhand. By Captain

JAMES FRANKLIN, First Bengal Cavalry, M. A. S. ‘

. On the Discovery of Vanadium in Scotland, and on the Vanadiate of

_ Lead, a new Mineral species. By JAmeEs F. W. Makes Si,
A. M. &c. &c. Communicated by the Author,

. On some properties in Achromatic Object-Glasses applicable to the

improvement of the Microscope. By JosEPH JacKsON LiIsTER,
Esq.

. Notice respecting the proposed Scientific Meeting at York, on Mon-

day the 26th of September, : ‘ Th

. Observations on Fossil Vegetables, accompanied by Representations

of their Internal Structure as seen through the Microscope. By
Henry Wirnam, Esq. of Lartington, Fellow of the Geological
Society of London; of the Royal and Wernerian Societies of Edin-
burgh, &c. . °

Register of the asia drbictiba: and Rain-Gage, kept at
Canaan Cottage. By ALEX. ADIE, Esq. F.R.S. Edinburgh, —

TO CORRESPONDENTS.

11

126

‘141

143 |

148

150

166

169

180

183

190

Mr MARSHALL’s Observations, and other papers, necessarily postponed, will ap-
pear in next Number.

CONTENTS

OF THE

EDINBURGH JOURNAL OF SCIENCE,

ART. I.
Il.

TI.

Vill.

No. X.

NEW SERIES.

loan: aaumieeh sets onion Gitding, Ue BA, cee & wP-.Bineriac se
F: R.S. Savilian Professor of Astronomy in the Retvenitn of Oxford.
Communicated by the Author, d 191
Ona New Analysis of Solar Light, indieating hed Dinars Colours,
forming Coincident Spectra of equal length. By Davip Brewster,
LL.D. F. R. SS. Lond. and. Ed. : 197
Further Remarks on the alleged Polarization of Hat By the Rev.
BaDEN PowE tt, M. A. F. R. S. Savilian Professor of Geometry in

the University of Oxford.. In a Letter to Dr BREWSTER, : 206

. On the General Equations for determining the Positions and Curva-

tures of Arches of Aurora Boreales, from observations made in one
place only; with Calculations for that of the 25th December 1830.
By &. Potr=rR Junior, Esq. Communicated by the Author, ,, 209

. Contributions to Scientific.Bibliography. By a LORPRSPOUDENT-

Communicated by the Author, 219
Silver Ores reduced by the Method of Seine! "By Aumins DEL
Rio. Communicated by a Correspondent,, . 222
A hetter from CHARLES CHEVALIER, Opticianyin Paris, pe Dr Go.
RING, being an Answer to his Paper published in the Second, Vo-
lume.of the New Series of the Quarterly Journal of Science, p. 248,
entitled, ‘* A Critique on the thick Aplanatic Object-Glasses for di-
vergent rays of Vincent Chevalier ainé et fils.” Communicated by
Dr GorRING, . ‘ . $ 223
On the Perfection of Microscopes. By LEONARD Sees. Com-
municated by Dr GorINe, 233

* TX. Remarks on Mons. Chevalier’s Piper, and on he Memoir of Euler.

X.

By Dr Gor1nc. Communicated by the Author, 238
On some properties in Achromatic Object-Glasses applicable to the

improvement of the Microscope. By JosEPH Jackson LISTER,

Esq. (Concluded from No. ix. page 180.) ‘ : 249

iV

XI.
XIi.

XIII.

XIV.

XV.

XVI.
XVII.

XVITI.

XIX.

XX.

CONTENTS.
>

P.

Account of the Aurora Borealis seen in Roxburghshire on the 5th of y=
October 1830. By Mr W. Latpiaw, Kaeside, : 252
On the Mean Temperature of Tu1rty-Four different places in the
State of New York, for 1830, ‘ 955
Remarks on Mr Potter’s Paper ** on the Specific heatt of Meta a

By James F. W. Migaig > 1, A. M. &c. &c. Communicated by

the Author, % : : 265
A few Remarks on an Account of the “ Mfootiniy of the Cultivators

of Natural Science and Medicine at Hamburgh in September 1830,

by James F. W. Johnston, M. A. &c. &c.” as Communicated by the
Author to the Edinburgh Journal of Science, New Series, No. viii

p. 189. By Dr MuncKE, Professor of Natural Philosophy at Hei-
delberg. Communicated in English by the Author, . 271
Observations on Professor MUNCKE’s Remarks on Mr JoHNSTON’S
Account of the Meeting at Hamburgh. In a Letter to the EprroRr
from Mr JOHNSTON, é K ‘ 278
Round Sterns. Bya dive wpa ieieae a 282
Observations on the Theories which have been sell to explain

the Vitrified Forts of Scotland. By S. Hrppert, M, D. F. R. S.

Ed. &c. &c. . ~ 285
Notice of the Discovery of very sities Vitrified Reinbics at Els-
ness, in the Island of Sanday, Orkney. By S. Hrppert, M. D.

F. R.S. E., &c. Ina Letter to Dr BREWSTER, f 309
Some Notices regarding Vanadium. By James F. W. JounsTon,
A. M., &c. Communicated by the Author, 318

On the Nature of the Light in the Two Rays phodiioel by the Double

Refraction of Quartz. By G. B. Airy, M. A. M. G. S. Late Fel-

XXI.

XXII.

XXIII.

XXIV.

low of Trinity College; Plumian Professor of Astronomy and Ex.
perimental Philosophy in the University of Cambridge ; and Fellow
of the Cambridge Philosophical Society, ‘ : 324

Description of a new Species of Lamprotornis. By JoHN BLACK-
WALL, F.L. S., &c. Communicated by the Author, . 332

Observations on a Pamphlet, entitled, “‘ On the Alleged Decline of
Science in England. By a ForErenER. London, 1831. Pp. 33.”
Accompanied by a Preface by M. Farapay, Esq. F. R. S. &c. 334
A System of Geology, with a Theory of the Earth, and an explana-
tion of its connection with the Sacred Records.. By Jonn MacCu.-
LocH, M. D., F. R.S., &c. In Two Volumes, 8vo. Pp. 512 and
483, : : 358
Register of the Barometer, Thidtnsdineter, and Risadange, kept at
Edinburgh. By ALEX. AprE, Esq. F. R.S. Edinburgh, 376

:
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THE
EDINBURGH
JOURNAL OF SCIENCE.

Ant. I.—Observations on the Decline of Science in England.

For several years we have availed ourselves of every proper
opportunity of pointing out to our readers the deplorable condi-
tion of English science, and the rapid decline of the scientific
as well as the useful arts. The language of admonition and of
expostulation was too feeble to make any immediate impression,
but the smallest impulse may produce a sensible effect by its
repetition ; and we have reason to believe that many individuals
were induced to turn their attention to the subject, and were led.
to discover within the circle of their own knowledge the most
palpable evidence of the bitter and mortifying truths which we
were the first to acknowledge and to bewail. A posthumous
work of Sir Humphry Davy’s contained opinions in unison with
ours, and Mr Herschel felt himself called upon not merely to
assert in general terms that the sciences of England were declin-
ing, but to bring forward specific and incontrovertible proofs of
the fact.

_ “In England,” says he, “ whole branches of continental disco-
very are unstudied, and, indeed, almost unknown even by name.
It is in vain to conceal the melancholy truth. We are fast
dropping behind. In mathematics we have long since drawn
the rein, and given over a hopeless. race. In chemistry the
case is not much better. Who can tell any thing of the sulpho-
_ salts? Who will explain to us the laws of isomorphism? Nay,
NEW SERIES, VOL. V. No. I. JULY 1831. A

2 Observations on the Decline of Science in England.

who among us has ever verified Thenard’s experiments on the
oxygenated acids? Oersted’s and Berzelius’s on the radicals
of the earths? Balard’s and Serullas’s on the combinations of
brome, and a hundred other splendid trains of research in that
fascinating science? Nor need we stop here. There are, in-
deed, few sciences which would not furnish matter for similar
remark. The causes are at once obvious and deep seated ; but
this is not the place to discuss them.” :

This powerful statement, which no person has ever dared to
controvert in the minutest particular, was followed up by Mr
Babbage’s bold and able work on the Decline of Science, of which
we have already laid before our readers a full account.

A review of this work appeared in the 87th Number of the
Quarterly Review, where the writer not only defended Mr Bab-
bage’s-views, but adventured upon the dangerous ground of
pointing out in the most fearless manner the causes which have
led to the decline of science. He exposed the infamous and
fraudulent system of our patent laws, and explained the im-
provements in our universities, in our metropolitan institutions,
and in our public boards, by which the genius of our country-
men might still be called forth and cherished, and the sonar as 28
glory of England preserved and extended.

The metropolitan and the provincial press took up the sub-
ject with their usual boldness and intelligence, and the facts of
the case were speedily diffused over all England. ‘Two par-
ties were of course arrayed against each other. Men of science
who had pursued it for its own sake, and who had distinguished
themselves by original discoveries, entered the ranks with Mr
Herschel, Mr Babbage, and Sir James South, and were sup-
ported by many of the intelligent and disinterested friends of
science; while another party, which we can scarcely charac-
terize, was carrying on an anonymous warfare in the bye-ways
of our periodical miscellanies. Individuals of no pretensions
even to science, and who had all their lives thought» that
there could be nothing either good or great out of England,
considered it as next to treason to state that the French ex-
celled. us in mathematics,—the Swedes and the Prussians’ in
chemistry,—the Russians in practical astronomy,—and the Ba-
varians in telescopes. The fanctionaries of scientific institu- —

Observations on the Decline of Science in England. 3

tions that had long been identified with English science, felt
themselves aggrieved by the mere allegation that science was
declining, and that their labours were gradually diminishing in
importance; and certain professors in universities, who had
_ never enriched science with a single fact, and yet considered
themselves as its guardians and depositaries, have raised a violent
outcry against facts which all but themselves knew, and against
opinions which all but themselves believe.

Cutting off the auxiliaries from both sides, we may safely state,
thatthe parties arrayed against each other on the question of
the decline of science, and the unfitness of our present institu-
tions to advance its interests, are certain professors in our univer-
sities on the one side, and the philosophers actively and con-
stantly engaged in original research on the other. Both of these
classes of persons are of the highest respectability, and exercise a
great and a just influence over public opinion; and thdse who are
led to form their judgment chiefly from the authority of names
will have some difficulty in taking their place in the controversy,
and will probably arrange themselves under the banners of those
men who enjoy a temporary and deceitful reputation from their
influence as teachers of youth. Many of these persons never
heard of Mr Ivory and Mr Dalton, and would scorn the idea of
their being greater men than some of our well-known and justly
esteemed professors. We must therefore furnish the intelligent
reader who wishes to form a correct opinion, with a test by
which alone he can decide which of the two parties are most
likely to form the most correct ane respecting the decline
of English science.

_ Original discoveries in science are rewarded in two ways,

either by the adjudication of prizes or medals to the discoverers,
or by honorary admission into foreign societies Among the
living cultivators of science in England, twenty-four honorary
medals have been adjudged by the Royal Society of London;
viz. nineteen Copley medals, given chiefly for the best papers in
each volume of the Philosophical Transactions ; two Rumford
medals for discoveries on light and heat; and four or five royal
medals for specific discoveries, Now it is a curious fact that
only a single professor received one of these medals, * viz. Pro-

* Mr Leslie, before he was a professor, received the Rumford medals, and
Dr Brinkley received a Copley medal as Astronomer Royal of Ireland.

4 Observations on the Decline of Science in England.

fessor Bucklarid. Several miedals havéibeen awarded by foreign.
societies to English philosophers, but none of them, have found
their way to any of our universities.

_ With regard to the honorary distinctions conferred by foreign. }

academies, we may state without the fear of contradiction, that.
the Institute of France is the only body which dispenses its;
honours with rigid impartiality. No adventitious circumstances,
are permitted to bias their decisions; and if a few votes should,
on particular occasions be influenced by personal feelings, they
are entirely lost in the unanimity which invariably characterizes
the election of associates and corresponding members. Now
there are at present in England nineteen corresponding mem-
bers of the Institute of France, and not one of them is a pro-
Jessor, or even a resident in any of our English universities.

—Professor Leslie, indeed, is the only one who fills a chair, but,
he had earned this honour before his brilliant talents were lost —

to science in the functions of a popular lecturer.

It will not be imagined by the candid reader that we mean.
to call in question the genius and talent of many eminent, pro-
fessors who adorn the universities to which they belong. We
appreciate fully their valuable labours as excellent teachers and
eloquent lecturers, and we see among them more than one in-
dividual who has begun to earn a brilliant reputation, and who,
if not overpowered by professional duties, will add to the scien-
tific glory of their university and of their country. , Professors
Airy and Whevwell of Cambridge, and Professor Hamilton of
Trinity College, Dublin, are the individuals to whom we more
particularly refer, though there are still others to whom we
look with a feeling of hope, which we trust will not be disap-
pointed.*

The great fact, therefore, of. the. decline of science, and.
the necessity of a reform in its institutions, are maintained
almost unanimously by the individuals who stand at_the
head of English science, and who represent it in foreign coun-
tries, and. by .a host of their distinguished fellow-labourers,
' many of whose names are recorded in the celebrated requisi-
tion signed by about eighty fellows of the Royal Society, which

_*<* Our remarks have no ‘reference to the: sciences of - hn such
as geology and natural history.

ote

—_— ee ee

Ee nt Pie ee - n, e e
F eee ne ae j ms
' : «

_ Observations on the. Decline of Science in England. — 5

called Mr Herschel to become a candidate for the presidency
of that institution. ‘Their opponents are the occupiers of ‘of-
fices.and chairs’ in the close burghs of our universities, who,
as we'have already proved, have not contributed: their proper
share to the scientific glory of their country, and who are thriv-
ing on the luxuries of pluralities and official emoluments. These
individuals have no sympathy for the condition ‘and hardships
of their scientific brethren, who, to their ardour for science,
have sacrificed all the advantages of professional ambition, and

who, in the nightly bivouac of a campaign that never ends, are

exhausting their minds, their healths, and their limited means
in advancing the interests of their species, and contributing to
the intellectual glory of their country. The privileged philo-
sophers believe, that in place of science declining, England sur-
passes all nations in her scientific men and in her artists; that
our philosophical institutions are nearly perfect, and that any
attempt to improve them would detract from the wisdom of our
ancestors, without adding to that of our posterity.

In these views we recognize the arguments which have been
used against any—even the smallest and the slowest improve-
ments in our political institutions ; and it is curious to discover
that the same persons who are opposed to a constitutional re-
form in our representative system are in general equally hostile
to a reform in our scientific institutions. Sir Robert Peel has
on more than one occasion expressed a disbelief in the decline of
science in England, and denied that it has not been sufficiently
encouraged by the government. Such opinions are a defence of
his own conduct as the Home Secretary of England. In this
high situation, it was his duty to observe the downfal of English
science, and to recommend measures for its recovery. Represent-
ing as he did a learned university,—deriving as he did, and as
he himself with much good taste declared,* all his importance in
society from the useful arts,—canvassing as he, or his friends
did for him, for the presidency of the Royal Society ; and en-
tering as he did the council of that body,—a peculiar obligation

was laid upon him to promote the scientific interests of Eng-

land,.and to improve the vicious system of her patent laws.
The force of this obligation he could not but feel, and the very

* Speech at the meeting for erecting a monument to Mr Watt.

6 Observations on the Decling of Science in England.

proofs which he has given of this feeling betray his unwillingness
to advance the interests of science. He recommended to his late
Majesty to give L. 100 per annum for two royal medals, which are
adjudged not to Englishmen alone, but to philosophers in every
part of Europe; and he advised his present Majesty to give L.300
per annum to Sir James South, a gentleman of great wealth, in
order, to use his own words, “ that the country should bear
some portion of the enormous expence which Sir James had in-_

curred in pursuing his researches!” and in order “ fo relieve -

the country from the charge of perfect indifference to subjects
of a scientific nature!” While the other governments of Europe

are building magnificent observatories, and purchasing the most _

expensive instruments for promoting astronomy, a British mi-
-‘nister recommends to his munificent Sovereign to pay some por-
tion of the enormous expences of a wealthy astronomer, and
never feels it his duty to propose any act of liberality to other
men who are involving themselves and their families in pecuni-
ary difficulties by the noble devotion of their entire minds to
the intellectual service of their country. But the British mi-
nister has another motive for this Irish act of liberality, namely,
the motive of self-defence against the charge of perfect indiffer-
ence to subjects of a scientific nature. Which of these motives
predominated and prompted the recommendation, we dare not
conjecture ; and, however others may think upon the subject,
we cheerfully admit that the grant to Sir James South relieves
the country from the charge of perfect indifference to science,
in the same manner as the miser would sustain his character for
charity, by passing by the poor man at his gate, and casting a
mite into the treasury of the rich.

In thus totally neglecting the scientific interests of his country,
Sir Robert Peel has only followed the example of his predeces-
sors in office,* and we have given our observations an especial
reference to him, because his conduct is best known to our
readers, and because being the last occupier of the Secretary-
ship of the Home department, and living at a time when the

‘diffusion of knowledge had ceased to terrify weak minds, the

* We beg to refer the reader to the Life of Dugald Stewart in this Jour-
nal, No. xx. p. 200, for an anecdote of Lord Liverpool, strikingly illustra-
tive of this opinion.

ee ee sD

Observations on the Decline of Science in England. 7

intellectual population of England were entitled. to expect from
him a more generous and enlightened policy. When the poli-
tics of D’ Alembert, Condorcet, Carnot and Voltaire, were quoted
as arguments againt science and literature, there might be some
apology for an ignorant minister when he yielded to the fears of
his still more ignorant abettors; but in the days of Sir Robert
Peel, such fears as these, if they existed at all, were to be found
_ only among men defective in reason, and could not even be felt,
still less urged, as grounds of hostility to the cultivation of
science. ‘The true cause of the indifference of the government
was this; the ruling party in Parliament did not contain one
single scientific individual, or one single patron of science.
There was therefore no influential channel through which scienti-
fic claims could be preferred; and in proof of this we can state on |
undoubted authority, that when application was made to govern-
ment for a grant to construct a great national machine, the mi-
nister durst not give his consent till he had obtained the con-
currence and recommendation of the eminent philosopher and
statesman who was the leader of the opposition. But it was not
merely ignorance of science and of its value to a nation that was
the cause of this evil. Corruption and ignorance lay with their
mingled poison round the tendrils of the tree of knowledge.
The fund with which the Sovertign was entrusted for reward-
ing merit was all required for the purposes of parliamentary cor-
ruption, and the offices which men of talent could have filled
with honour and utility, were all reserved for the tools of faction.
In reply to these observations, it is usual to adduce some acts

of liberality and justice. Is not such a scientific and literary
name on the pension list? Was not L. 12,000 or L, 15,000.
given for a mineralogical survey of Scotland? Did not several
expeditions of discovery sail from our ports? To these ques-
tions we answer in the affirmative: But if we were to inquire
into the real history of these transactions, we should find that
many of them were the merest jobs, though the avowed object of -
them was praiseworthy ; while others were the tricks or ex-
- pedients of a designing minister, to throw round his measures a
thin halo, sufficient to conceal from the people his own scheme of
personal aggrandisement. What is it to science that two me-
dals are given annually by the Royal Society in the name of

c° Observations on the Decline of Science in England» e

the King of England to a British or to a foreign philosopher?
What is it to science that a wealthy individual receives L. 10,000.
for a scientific survey, which could have been executed for
L. 1000? or that several expeditions, got up avowedly for a sci-
entific object, but really for the benefit of naval men, have left
our ports without a single astronomer, hydrographer, or natu-
ralist on board? But though such fragments of a shallow and
deceitful policy are nothing to science, yet they are everything
to a minister. He pleads upon them as points of character, .
and when his insincerity is unmasked, and his miserable expe-
dients detected, he consoles himself, and blinds his friends, by
the proof that he was not perfectly indifferent to the great inte 3
rests that were confided to his care.

The object of these observations is to introduce to the conden
the opinions of an able cultivator of science, resident in India,
respecting the comparative condition of the sciences in England
and France, and respecting the decline of science in England.
These opinions are given in an excellent work published at Cal-
cutta, entitled Gleanings in Science; and we believe we need
not scruple to say, that the author of them is Captain Herbert,
assistant surveyor-general of India, and late superintendent of
the mineralogical survey of that country. ‘To the sentiments
which this disinterested and able writer has expressed, we would’
beg the particular notice of our readers, especially of those who
may be disposed to entertain an opposite view of the:subject ;
and we would direct his particular attention to the absolute co-
incidence between Captain Herbert’s views and those of Mr
Babbage, Mr Herschel, and the writer of the article on the de-
cline of science in the Quarterly Review.

‘“‘ If to the labours of the officers of La Chevrette we add,
those of MM. Diard and Duvaucel, of M. Dussoumier, and of
a gentleman well known in Calcutta, now busily employed in
investigating the natural history and physical geography of In-’
dia, we shall be forced to confess, however humiliating the ac-;
knowledgment, that France will have done more in the short
period of the peace for making India known to the scientific _
men of Europe, than England has in the whole period during
which she has held the country. ‘There is a general spirit of
scientific research diffused throughout the French nation, which. —

Observations on the Decline of Science in England. 9

can only be attributed to the great interest taken in these inqui-
ries, and to the encouragement afforded to their pursuit by the
French Government. In England a very different state of
things prevails. There, with a few occasional exceptions, every
thing is left to private emulation and the promptings of com-
mercial enterprise ; so that those branches of science which do
not bear so strongly and directly on public utility, as to offer
by their cultivation the prospect of fair commercial returns, are
left altogether to their own unassisted resources. Yet, even in
the vulgar calculation of pounds, shillings and pence, it is a
question, whether the policy of the French Government is not
superior to ours. It is at all events certain, that their well fur-
nished museums, with the fame of their savans, have the effect
of attracting numerous Visitors to their capital. It is equally
certain, that if any one thirst after scientific knowledge he will
go to Paris, as being sure to find there such aid, with ‘ all ap-
pliances to boot,’ as can be had in no other city in the world.
In fact, if London be considered the capital of the commercial,
Paris may be said to be that of the scientific, world, which,
though a smaller body, is not without its influence ; at least for
good, if not for evil. Paris is pre-eminently the city of the
sciences—yet why it should be so, save from the indifference of
our influential personages, it would be difficult to say.”

Captain Herbert enters still more fully into the subject in his
analysis of Mr Babbage’s book, which he appears not to have
seen when he composed the preceding extract.

‘¢ The picture,” says he, “ which is here drawn of the state of
English science is melancholy in the extreme, and certainly makes
the wonder less that we should be so much below the nations of
the continent in the cultivation of every branch of science. In
one point, however, we differ from our author: he considers the
vile system he has exposed, to be the cause of the decline of
science : we, on the contrary, are disposed to think that science
must already have been at a miserably low ebb in any country
where such things ‘ can be, and not o’ercome us as a summer
cloud with special wonder.” Where such things could pass as
every-day matters, there science must have already declined.

‘* ‘That the low state of science in England is mainly owing to
the system of education, is an opinion we had ventured to give be-

10 Observations on the Decline of Science in England.

fore seeing the present work ; and'we are glad to see this opinion
confirmed by one so much more competent to judge. He. ob-
serves—‘ A young man passes from our public schools to the
universities, ignorant almost of the elements of every branch of
useful knowledge; and at these latter establishments, formed
originally for instructing those who are intended for the clerical
profession, classical and mathematical pursuits are nearly the
sole objects proposed to the student’s ambition.” The perti-
nacity with which we cling to a system of education established
in the dark ages, and for a particular class, is indeed character-
istic of our nation—as one jealous of innovation and intolerant
of change. Yet the many practical evils of our perseverance in
so absurd a course, generally acknowledged as they are, would
seem to be more than sufficient warrant for a new experiment.
That some improvement must take place sooner er later, seems
evident, but in the meantime we have lost ground in the race,
and have allowed ourselves to be outstripped by all the world,
even by that scion from our stock, America.
** It-is a consequence, it appears to us, of the little attention
paid to science in England, that, unlike the other countries of
Europe, it has no separate class or profession, devoting itself to
the exclusive cultivation of science. All our scientific charac-
ters belong to other professions, on which they depend for their
provision, their scientific labours being occasional and desultory.
One consequence of this state of things must be, that owing to
the claims on their time made by their profession, few of the
investigations they engage in can be pursued to a satisfactory
issue—nor is it scarcely possible that they should ever attain
excellence while their attention is thus divided. A second
consequence is, that there is wanting that stimulus of profes-
sional rivalry which would often prompt to great discoveries,
and equally that wholesome supervision exercised by a profes-
sion over all its members, which, giving to each man the credit
which he is justly entitled to, is as certain to reward merit as it
is to mark deficiency. If a man, ignorant of law and lawyers,
wish to employ the first counsel, let him inquire to whom the
profession generally look up, and he is not likely to be dis-
appointed in his choice. So also in other professions or dis-
tinct classes, in which an esprit de corps seems to give every,

‘Observations on the Decline of Science in England. 11

even the lowest, member a sort of interest and pride in the suc-
cess and efficiency of the highest. But scientific men in Eng-
land have no esprit de corps—the consequence is, they-are di-
vided into coteries, parties, cabals. The interests of science are
thus lost in the squabbles and party differences of individuals,
and the result is every way mischievous. It is not the least
evil of this state of things, that no union of effert, or concert of
aim, can be expected from them.

‘< Our system of education is undoubtedly the root of the evil,
yet it is not sufficient to account altogether for the low estima-
tion into which true science has fallen, or for the fact of its
having been almost universally replaced by the contemptible
system of tricking and puffery here exposed. An. almost equal-
ly powerful cause will be found in the want of national encou-
ragement, which is the disgrace of England. In the true spirit
of a nation boutiquiere, it is said that every commodity, and
science amongst the rest, will always, if left to itself, fetch its
true value; and that, if required by the public, the demand
will necessarily occasion the requisite supply. But the maxim
thus applied is as erroneous as it is contemptible. Mr Bab-
bage has well shown that science consists of two parts, theory
and -practice—in other words, principles and useful results.
The latter are the effect of the application of those principles to
the affairs of life. Now the investigation of each class of truths
is so distinct, that seldom or ever do the qualities of mind, re-
quisite for their discovery, unite in the same individual. But
it is the latter alone that the public know any thing of, and con-
sequently to those who excel in the discovery of practical ap-
plications, and to them alone, is the encouragement of the pub-
lic given. The investigator of the principles which have been
applied, though equally entitled to the reward, is altogether
lost sight of. The discoverer, for instance, of the principle of
latent heat, as it has been called, had no share of the immense
reward which fell to his lot, who suggested merely one applica-
tion of so general a law. Yet had Watt not known of this
law, would he have ever stumbled on the capital improvement
of condensing the steam in a separate vessel. ‘The inventor of
the reflecting quadrant could have done little but for the pre-
viously known laws of optics; nor could the astronomer have

Madi”

12 Obser'vations on the Decline of Science in England.

derived ‘much benefit from ‘the instrument, when invented ’as) ~
applicable to determine the longitude, but for those abstruse re-
searches of the mathematician, which, assisted by a few obser-.
vations, enables him to predict the exact place of the heavenly’
bodies. It will, in fact, be found throughout, that theory and
practice must go on together, or, to speak more correctly, prac-'
tice cannot move a step but as she leans on theory. The’
limits of the latter will be the limits of the former. Now what
encouragement has any one, however well qualified by nature,
to devote himself to this branch of the subject? If he be in-
dependent, he may perhaps, urged by the strong bias implanted
by nature, pursue a path where neither profit nor: distinction,
as emanating from the government, await him; but if he has
to struggle against the angustas res domi, he will of course
turn his attention and talents to some more promising occupa-
tion. } ad
<¢ In other countries the case is different ; there men of science
not only reap distinction and pecuniary reward, but are consi-
dered eligible to the first appointments in the state. Mr Bab-
bage gives a long list of these; amongst which we may men-
tion, as known to our readers, Laplace, a Marquis, and Presi-
dent. of the Conservative Senate; ‘Carnot, Minister of War;
Chaptal, a Count, and Minister of the Interior ; Cuvier, a Ba-
ron, and Minister of Public Instruction: the latter, too, having
to struggle with the prejudice against his religion, (the reform-
ed.) The consequence of this difference of system is, that on
the continent, and specially in France,'science is*in the most
flourishing and prosperous condition ; while in England we’are
day after day losing all that once made our distinction. Even our
mechanical arts connected with science, the encouragement ‘of
which can never be trusted to the commercial spirit, are fast
losing ground. The achromatic telescopes of Dollond, which
once made us a name all over the globe, have been eclipsed by -
the productions of an establishment at Munich, assisted as they
were by the successful efforts.of an obscure Swiss clock-maker,
to manufacture glass of a superior quality,-and in larger pieces.
This is one of the many: practical evils attending that total’in-
difference to the scientific character of the country, which is
particularly indicative of a Government incapable of apprecia-

Observations on the Decline of Science in England. 13

ting the value of science, and ignorant of the fostering cares
required to assist its progress.” —Pp. 229-230.

- In order that our readers may possess the opposite view of
the question, we quote the following observations from the
Quarterly Review, No. 89, which profess to be the substance
of what has been urged by eminent ! scientific pene in reply
to Mr Babbage and his friends. i

‘* Men of science,” says the Reviewer, ‘* continue to be bi 2
divided in opinion as to what is, and what is not, the sort of en-
couragement which the government of this country ought to give
to scientific inquiry.. The views of Mr Babbage, and many
others, have been abundantly explained to our readers in a late
article; but these are strenuously opposed by persons equally
eminent,*—according to whom the case stands thus:

“< Whenever the investigation of certain topics would be useful
to the public service, but, from whatever cause, such investiga-_
tion is not likely to be undertaken by individual members of
the community, it is the clear duty of government, acting as
stewards or agents of the public, to employ the means placed in
their hands for the advancement of such objects ; but when the
members of the community are themselves willing and compe-
tent to prosecute the inquiries, the interference of government
would be not only useless, but hurtful. There cannot, they
proceed, be a doubt that the philosophical pursuits to which the
learned members of the French Institute devote their time, are
highly beneficial to their country; or that the government of
France does well to pension the savans, and to invest them with
honours, that these able men may be stimulated to fresh inqui-
ries. If science in that country were not kept up by the -pro-
tecting hand of government, it would soon languish and die ;—
not because those accomplished philosophers, who ‘are the ad-
miration of Europe, are at all lukewarm in their. pursuits, but
because there is not, in the community at large, either a suffi-
cient degree of taste for such things to render them generally
fashionable, or enough of wealth to make them profitable. . In
England, they assure us, it is quite otherwise. There is not
only a very extensive taste for every description of science dif-
fused throughout our country, but there is ample wealth, always

" * Who are the persons equally eminent with Mr Herschel and Mr Bab-
bage ?

14 Observations on the Decline of Science in England.

ready, upon the slightest hint, to support. the expences of such
investigations. (!!)* For government, therefore, to interfere in
England with such things, would be like dashing with the oar
to accelerate the cataract. ‘There is abundance of momentum
already impressed upon the body, and any additional force ap-
plied to it would be wasted. It matters little what may be the
object of inquiry in this country; whether it be abstract and
refined, or practical and immediately useful—or whether it com-
bine the practical with the speculative—or even if it be altoge- —
ther absurd and visionary. Let any subject of inquiry be start-
ed, it is straightway pursued with ardour; and there is no in-
stance that they have heard of. in which any such inquiry has
been retarded for want of due encouragement. (!!) + Proceeding
to examples, they tell us there was a time when the Royal So-
ciety was supposed to be the only grand fountain of knowledge
in the kingdom. At length, certain of its members conceived
their favourite pursuit not sufficiently attended to, and in a few
months was established the Geological Society. Since that
period, the astronomers have, in like manner, set up for them-
selves; and so far from being in want of further encourage-
ment, these interesting bodies derive, from the pockets of their
own members, every assistance they can possibly desire. These
are only two out of many similar societies in London, all of
them numerous, and all of them supported by the voluntary
contributions of their own members. But the other day Mr
Barrow pointed out the want of a society which should devote
itself expressly to geographical subjects, and in less than three
months, five hundred and fifty members came forward to enter
their names, all ready to pay their subscriptions, and upwards of
a hundred of them to compound by a ten years’ purchase for their
annual payments. ‘We are asked if, after this, we can question the
sincerity and zeal with which scientific objects are de Sacto encou-
raged in England? We are told that we should surprise our rea-
ders were we to lay before them an account of the sums of money
actually paid annually by the scientific and literary bodies of
the metropolis alone, to say nothing of those which may be

y Where i is this wealth to be found? The statement is most incorrect,
+ These persons must be very ignorant of the state of scientific inquiry
in England.

s
Re
.

*

Observations on the Decline of Science in England. 15

found in almost every town in the empire. We are asked if —
the money thus raised by voluntary and cheerful contribution,
and expended most judiciously on purely scientific objects, is

_ not only fifty times greater than the whole amount so ostenta-

tiously distributed by the government of our neighbours; but
fifty times greater than the executive of this country could ven-
ture to collect for any such purpose, or would be permitted to
bestow even if they did collect it? Then as to titles and other

external distinctions, is it not precisely because such honours

are distributed with a sparing hand im this country, that they
are felt, when bestowed, as of real value by the individuals
selected, and carry solid weight with the body of the nation? -

“© Having thus stated the substance of what has been urged
among scientific people, in reply to Mr Babbage, and part of
our own reviewal of his late treatise, we consider ourselves as
having given all readers the means of judging for themselves
between the contending parties. ‘Truth, as in most cases, may
most probably lie between. That all Mr Babbage’s complaints
and our own have been answered we do not think; but croak-
ing is not our element, and it is a pleasing relief to do jus-
tice to the admirable style in which, with regard to one great
object of scientific inquiry, the British government in our day
has unquestionably done its duty—carrying the wishes of the
country into effect, by bringing its resources to a focus, and ap-
plying them in a manner which the government alone could
have had the means of doing,—we allude to the case of arctic
discovery. * * * * *

*« It is fair, then, to own, that in our view, Mr Babbage and
his allies should not have passed in silence what has been done
by the executive for this single investigation.”

With some of these observations ‘* Mr Babbage and his allies”
will not be disposed to quarrel ; for they have themselves expe-
rienced how great a demand England makes upon the generosity
of individuals for the support of her scientific institutions: but:
this very fact is the result of the indifference of the government,
and is the most satisfactory proof of it that can be desired. We
beg, however, to remind the learned author of the preceding
extract, that societies may meet in countless numbers,—may
elect their functionaries,—-and publish their transactions,—and

16 Observations on the Decling of Science in England.

compound for their annual payments,—and “ eat their white
bait,”"—while inventive genius has been blighted by the disfa-
vour of government, and all original scientific research entirely
extinguished. ‘The enormous sums of money collected by so-
cieties, and which, by a strange hyperbole, the reviewer states
to be fifty times greater than that distributed by the French
government, afford an irrefragable proof of the position main-
tained by Mr Babbage. They are wasted in house-rent, taxes,
wages of servants, and expensive transactions; and it would be
difficult to point out any well marked instance where the funds
in question have been applied to promote the direct interests of
science or of scientific men.

With regard to the Arctic expeditions, Mr Babbage and his
allies had nothing whatever to do with the consideration of them ;
and in asserting the scientific pre-eminence of France, no notice
was taken of her admirably conducted voyages of discovery. A
British ship of discovery may be at work in every parallel of lati-
tude, and yet the mathematical and physical, and even the natu-
ral knowledge, and the scientific arts of England, may be utterly
extinct. The interests of naval men would indeed be promoted ;
but as men of science have been carefully excluded from all such
expeditions, we must judge of their utility solely by their results.
Of these results we have often spoken in the highest terms of
praise; but if we compare them with the enormous expence at
which they have been obtained, they sink into comparative insig-
nificance ; and we have no hesitation in stating, that the enormous
sum admitted by the reviewer to have been lavished on our nine
voyages of discovery, would have formed a capital for endow-
ing the most noble establishments for encouraging and reward-
ing scientific merit, and promoting the best interests of England:
The ministers of Great Britain never failed to distribute the
national treasure with a liberal hand, provided it was to be
spent by the Lords of the Admiralty, or the Board of Ordnance.
Offices, and honours, and petisions, were heaped in profusion off
military and naval men, as if no other kind of merit deserved
their notice. But it is to be hoped that these dark times are
gone,—that the eclipse of science is oyer,—that the arts of
peace will replace those of war,—and that a regenerated govern-
ment will study to foster the true interests of their country.

~

Mr Forbes on Polar Temperature. 17

- Art. II. nceGleotmations respecting Professor Leslie's For-
mula for the Decrease of Heat in the Atmosphere ; and his
Opinions respecting the Polar Temperature. By James D.
Forzes, Esq. F. R. S. Ed. Communicated by the Author.

My Dear Sir, :

- As I know that in every question of literary justice, nunguam
sero is your motto, I cannot help drawing your attention to an
atticle which appeared some years since in your Journal, com-
municated by an anonymous correspondent. It is in No. ix.
First Series, and has for title, ““ Demonstration of Professor
Leslie’s Formula for determining the decrease of Heat depend-
ing on the Altitude, without ‘a delicate and patient research.’ ”
It is only very recently that, having paid attention to this very
curious subject, I have been led to examine every statement
connected with it which came under my observation. Now
the article to which I allude excited my particular attention,
and the result of my inquiries into the merits of the case was,
that the author of it must, to say the least, have been very
imperfectly acquainted with what had been done on the sub-
ject. His demonstration amounts merely to this, that, from
the ordinary logarithmic formula, he undertakes to give one
which shall be identical with the law of uniform decrease of
temperature, at the rate of 1° Cent. for 81 fathoms of altitude.
To do this would indeed have been a small boon to science,
and we might certainly have expected, that, instead of confin-
ing himself to the undemonstrated enunciation contained in
Professor Leslie’s Elements of Geometry, he would have con-
sulted the article Climate, in the Supplement to the Encyclo-
peedia Britannica, which was even then published some years,
where he would have discovered, that the ‘‘ delicate and patient
research” alluded to was of an experimental kind, and so de-
serving of that appellation, that, frgm the very refined nature
of the experiments, (which were instituted to determine the
capacity of air of different degrees of density for heat,) few
philosophers have been disposed to place the same confidence
- in the deductions to which they lead, as the Professor himself
has done. Indeed, previous to the appearance of the article
before us, a highly distinguished philosopher had expressed his

NEW SERIES, VOL. V. No. I, JULY 1831. B

18 Mr Forbes on Polar Temperature.

surprise at the coincidence of observations, with principles de-
duced from such experiments, which could only be repeated ¢ on
the small scale.* But what makes me farther regret the ap-
pearance of the article in No. ix. of your Jowrnal, is, that the
demonstration from the logarithmic formula had actually been
given by Mr Ivory in the paper to which I allude,—not, how-
ever, for the purpose of showing that Professor Leslie’s formula
was incorrect, because it deviated from the law of strict pro-
portionality to the heights,—but to point out the relation which
it bore to such a law,—a law which, I believe, is now supported
in all its generality by few philosophers. Let the formula,
therefore, be examined on its own merits, such as they are;
but let it not be condemned as a mere rude approximation to
a known law given under a new form. I may also add, that,
instead of referring it to the barometer, as im the expression

26 (5-3): Professor Leslie now puts it under the more
correct form of 25 (5 — 6 ) where ¢ is the density of the air,

which includes the influence of temperature.

Having thus acquitted myself of what I considered it my

duty to do when I was enabled fully to clear up the facts of the

case which had recently engaged my attention, I take this

opportunity of saying a word or two upon another speculation
of the same philosopher, which I am afraid has less ground in
experiment than the so called “ delicate and patient research.”

Whilst I saw Professor Leslie’s opinions on the Mean 'Tem-
perature of the Pole confined to purely scientific works, I had
comparatively little anxiety to attempt to show their fallacy,
because the few who might there peruse them could in some

measure be considered as judges of the data upon which they

were founded. But when I see the same theoretical deduc-
tions brought forward in support of assertions, against which
conclusive experiments strongly militate, in a work of a purely
popular character, and of considerable circulation, + I could

have wished to see the question brought forward in its true —

light by some one more competent to the task than myself ;

* Philosophical Magazine, 1821.
+ Edin. Cabinet Library, Polar Regions, p. 12,
; -6

a a ne se - = one

———— =
ee a ee a ey eee

Mr Forbes on Polar Temperature. 19.

but a second edition having appeared without any amelioration
in this particular, I cannot help pointing out, in the first place,
the inexpediency (to use no stronger a word) of putting con-
clusions, purely speculative, against the weight of stubborn
facts ; and, in the newt, I shall endeavour to show the fallacy
by which these two results have been set in opposition to one
another.

I say nothing as to the general question of Mayer’s empirical
law of climate; I confine myself to the important assumption
to which its principal deviations from observation may be traced,
that the mean temperature of the Pole is 32° Fahr.,—an opi-
nion which Professor Leslie long maintained, and has only now
modified, by reducing it to 28° Fahr.,—the freezing point of
sea-water. ‘That in the time of Mayer such a position should
have been maintained, need not much surprise us, since few
observations had been made of the meteorology of the higher
latitudes ; but that in our own day, when Humboldt had shown
that the Isothermal line of 32°, passed between Lat. 65° and
71° in Europe, and as low as 55° in America ; * and above all,
when the direct experiments of our Arctic navigators had shown
that the mean temperature of the Pole must approach zero of
Fahrenheit nearer than 32°, some strong cause must be as-
signed for scepticism. The grand obstacle to the admission of
these truths is the supposed consequence of so low a tempera-
ture in increasing to an indefinite extent the accumulation of
ice in the Arctic regions, —an effect which has certainly not taken
_ place; for (as Mr Leslie justly remarks) the length of the
day would thereby be increased, which can be shown not to
have happened even to the most minute amount during the
last 2000 years. Now, taking up the question even at this
point, we have a right to call upon all who support the modern
system-of inductive philosophy, to subject speculations to facts,
and, however singular might appear the stationary quantity of
Polar ice, to put into the class of unresolved phenomena the
low temperature of the Polar regions, determined during a
large portion of several different years, by Parry, and Frank-
lin, and Scoresby, and Lyon, and, least of all, attempt to avoid
the force of the cumulative evidence of registers, which meteo-

* Mémoires d Arceuil, tome iii. p. 525.

20 Mr Forbes on Polar J’emperature.

rologists at home would do well ‘to emulate, by ascribing the
monstrous deviation of aoontyiey or thirty degrees to “ latent
and material inaccuracies.”

But, upholding i in the first place such a submission of theory
to experience, I propose, with all deference, to offer an explana-
tion of the supposed anomaly, that ice does not accumulate
under the Arctic Circle. This I,shall endeavour to do by show-
ing, first, the difference of operation in the formation and dis-
solution of ice ; second, the influence of marine, —and lastly, of
aérial currents.

I. That the mean temperature of a climate is the only ira
of the preponderance of the power which forms, or that which
dissolves, ice, has been thought an undeniable fact, because,
though vegetable productions may, under other circumstances,
be equally matured in climates differing much in mean tempe-
rature, this arises from the comparative intensity of the heat

of a short summer, which is yet sufficiently long to bring par- —

ticular crops to perfection. But, with regard to the summer
and winter effect, however distributed, upon ice, it is argued
that the effect must depend solely upon the mean temperature,
because the conversion of water into ice, and the reconversion
of the latter into the former, require a degree of comparative
cold in the one case, and of comparative heat in the other,
which admit of arithmetical estimation, and are precisely com-
mensurate. All this is undeniable ; but if we examine the mode
of the formation and dissolution of ice, we shall find an admir-
able provision of nature for preventing the former action from
overbalancing the latter. Suppose the sea reduced at the sur-
face to 28°; if a sudden fall of temperature in the air takes
place, ice will be formed very rapidly,—even to several inches
in thickness in one night. But observe the effect of the con-
tinuance of cold: the thickness of the ice cannot be increased
on that side next the frigorific influence, namely, the’ atmo-
sphere; the material is the sea-water, and exists only below ;
the influence of that intense cold, therefore, which lowers by

so great a number of degrees the annual mean, must be exert-

ed through the difficult conductor of the mass of ice already
formed, and the intensity of its impression is always rendering
more tedious the accession of cold to the sea-water, by thick-

a

‘
—

Mr Forbes on Polar Temperature. 21

ening the defence of ice; the mean temperature of the air may
thus be indefinitely low, whilst that of the junction of ice and
water cannot be under 28°. But mark the contrastiof the pro-
cess of thawing. Here the material for operation, or the ice,
is always exposed to the atmospheric influence; here there is
no difficultly conducting medium to shelter it from the oppo-
site extreme; but not only this, for we have the authority of
Professor Leslie himself for saying that the dissolution com-
mences newt the water. It is actively going on upon both sides
of the ice at once; the currents of warmer water ascending from:
lower latitudes are able to effect the partial destruction of the
fields before the solar rays have acquired sufficient power to
commence their active energy above. But not merely do these
causes combine to this great end, but the fall of rain, and the
insinuation of moisture through the pores of the ice, tend to
its rapid dismemberment ; yet Mr Leslie has confined his cal-
culations to the mere thickness of a cake of ice, which the so-
lar rays, with a given degree of obliquity, can dissolve.

II. We must attend to the important, but little known, ope-
rations which nature is constantly performing through the
agency of marine currents, before we can pronounce upon the
quantity of ice melted under a given latitude or mean tempe-
rature; and we have just quoted the best authority for the
fact, that the commencement of the thaw-is from below. The
laws of hydrostatics prepare us for the fact, that currents of
various kinds, and modified by an infinity of local circum-
stances, must effectually prevent stagnation in the ocean, and
preserve a certain interchange between the Equatorial and Po-
lar regions. Their precise nature and extent must often be
disguised or wholly unperceived, especially from our ignorance
of. causes in action at great depths, which must be materially
modified by the remarkable law of the irregular variation of
the volume of water by heat, from which it follows that water,
perhaps near 50° of temperature, may have a superior specific
gravity to surface water at the freezing point of the ocean, or
28°. It is easy, therefore, to speculate upon the sudden effects
which may ensue from the action of currents at the critical
moment of the disruption of the ice, and, though easier to spe-
culate upon than to analyze, there are none so bold as to deny

AZ Mr Forbes on Pola® Temperature.

the powers which nature thus holds in store, and which may
be operating the most important ends, although out of the
reach of our senses.

III. The last point upon which I have to insist, (for I ony
touch upon what I consider the most important facts,) is the
influence of aérial currents, or the strong north winds which
prevail in the Arctic regions at the.time of the breaking up of
the ice. If we refer to the details of navigators, we shall find
that the phenomena of this period are very different from what
philosophers in their closets generally set about theorizing upon.
The latter would imagine to themselves a lake or pond having
acquired a few inches of ice at a temperature little below 32°;
here indeed the process of the dissolution is slow enough;—but
how different is ice in its own proper region, with a temperature
of about 30 below zero, in the month of March; it suffers a
_ rapid and irregular expansion of volume in the succeeding
month, when winter suddenly rushes into the comparatively
intense heat of the short-lived Arctic summer. The icy fields
are ruptured with tremendous violence, and separate with a
fearful crash from the eternal glaciers of the ice-bound shores
to which they were cemented. All causes become at once ripe
for action ; the expanded volume of the crust,—the liquefying
influence of now powerful solar rays, and the penetrating effect
of showers, prepare every thing for the action of those prevail-
ing northerly winds, which, by the accounts of navigators,
in a few hours change totally the whole aspect of the horizon,
as far as the eye can reach; and hurry whole thousands of
acres down to more southern climates, where the greater part
is speedily melted by the joint influence of solar warmth and
a higher mean temperature of the ocean; but some masses
even reach extremely far into the Temperate Zone. Can we
then fail to see a vast difference between the process of freezing
and of dissolution; and have we not shown, even in this rapid
sketch, sufficient causes to account for the apparent anomaly
which we proposed to explain? I perfectly agree with Mr
Leslie, that, “‘ to discuss with accuracy the question of the pe-

riodical formation and destruction of the Polar ice, it becomes —

necessary to explain the true principles which regulate the dis-
tribution of heat over the globe ;” and I have only. to regret

a Se ee

eee

Mr Potter on the Aurora Borealis. 23

that he did not, as he promised, ‘‘ attempt to perform it indepen-
dent of every hypothesis, by a direct appeal to experiment and
observation. ”* Tremain, my Dear Sir, ever most truly yours,
J AMES D. Fores.
5th March 1831.
To Dr Brewster.

Art. III.—Observations on the Meteor called the Aurora Bo-
realis, with Calculations, Trigonometrical and Analytical, to-
wards determining the position and the course of the Arches,
with respect to the surface of the Earth. By R. Potrer,
Esq. Junior. Communicated by the Author. ‘

Tue magnificent meteor called the Aurora Borealis has been
one which has awakened throughout all ages the feelings of
wonder and astonishment in the minds of mankind. Amongst
the superstitious it has been always regarded as an omen of
fearful portent, betokening the most awful calamity to the in-
habitants of the earth ; and though we now look at it with a
philosophic eye, and speculate on its connections with electricity
and magnetism, its wonderful and ever-varying forms of
shining nebulous masses, of spiring evanescent streamers, or
more lasting and not less magnificent arches, with the brilliant
tints which it occasionally assumes, excite still in us amaze-
ment and delight whilst viewing it as an exhibition of one of
nature’s operations on a scale which our imagination in vain
endeavours to grasp. It is no matter of surprise, then, that
since the revival of learning, this meteor should have often at-
tracted the attention of philosophers to consider its nature and
causes, and, in connection with these, its position in space, or
its height above the surface of the earth: indeed, until we can
with some precision determine its locality, it is in vain to spe-
culate on the extent of its dependence, either on the atmo-
sphere or even the more ponderable parts of our planet; and
hence to determine its height is the first step we can take in
the investigation, and it is a matter of disgrace to science at
this day that such discordant opinions should prevail amongst
scientific men on the subject.

* Polar Regions, p. 7.

24 Mr Potter on the Aurora Borealis.

Amongst our countrymen, Mr Cavendish had, by trigono-
metrical measurement, computed the height of an arch to be
between 52 and 71 miles, and afterwards Mr Dalton, by the
same method, on a base of 22 miles, found the height of an
arch to be about 150 miles ; see his Meteorological Essays,
page 175; and from the observations of others, he has since,
see Phil. Trans. for 1828, brought out the height of another
arch to be at least 100 miles. These computations would un-
doubtedly place the meteor at a distance from the earth at
which the atmosphere, if it reaches it at all, must be of the
greatest rarity, and where the aurora must be almost beyond
the immediate effect of the ordinary changes near the surface.

An opinion has been adopted by Lieut. Hood and Dr Ri-
chardson, from observations made during the northern over-
land expedition, that the meteor occurs in the region only just
above the clouds, and the same view has been supported by
Mr Farquharson of Aberdeenshire,—see his papers in the
Phil. Trans. for 1829 and 1830. ‘These observers have made
no sufficient trigonometrical measurements to give even a plau-
sibility to their views; they seem to have been governed in
their opinions by hypothetical assumptions of the aurora being
an electrical phenomenon, depending on the condensation of
aqueous vapour ; instead of first seeking correctly its height,
and then forming their theory.

It is so easy a thing to any person who sees an aurora which
passes nearly over his head, to convince himself, even without
either instruments or possession of the ordinary mathematical
knowledge, that it is more than a few miles from him; that I
consider it a reflection on any one’s capacity and judgment, who,
having once seen it so situated, comes to the conclusion that it
is only just above the region of the clouds. And of those who
have not observed the aurora,.and would yet be anxious to
support the same opinion, I should say unhesitatingly, that
they are either ignorant of what has been done on the subject,
or entertain an unphilosophical bias, which prevent their exa- .
mining it correctly.

I have myself watched many Aurora Boreales, and had the —
good fortune to observe the one on the evening of the 29th
September 1828, of which J left amemorandum of particulars
with Mr Dalton, the next morning. Accounts of the same

;
;

Mr Potter on the Aurora Borealis. 25

arch have been given in the Philosophical Magazine, by Dr
Burney of Gosport, Davies Gilbert, Esq., Captain Kater, and
Mr Utting. And three gentlemen of my acquaintance, who,
having arrived by the steam-packet, were proceeding from King-
stown to Dublin outside the coach, were struck with the bril-

liancy of the arch, which passed almost exactly over their heads.

And it is rather an unaccountable circumstance to those who
adopt Lieut. Hood’s and Dr Richardson’s views, that the
whole of the observers speak of seeing only one arch.

To meet the objection, that the observers at different places
are generally viewing different arches, I, a short time since,
caught the idea, that, if we knew the direction which these
arches, (the only part of the phenomena which afford sufficient |
data for determining the height in the first instance with any
degree of exactness,) take over the surface of the earth, then
when they are at different elevations, their apparent curvature
cannot be the same for every different one ; but on the assump-
tion that we have found the law of their true curvature, their
height and distance might be determined from their apparent
one. On further considering the subject, I found that, if the
law of the magnetic variation were exactly ascertained, and
could-be reduced to a general formula, then the height of an
arch must be determined accurately from its apparent curva-
ture when it was symmetrical ; or at an even distance from the
earth in every part; the only reason we can give for the very
symmetrical appearance they frequently take ; and it is univer-
sally allowed that they then are found at right angles to the
magnetic meridian.

With this basis we may now examine the different theories
which have been advanced, and compare them with trigono-
metrical computations. Lieut.. Hood, Dr Richardson, and
Mr Farquharson consider the whole phenomena as at low ele-
vation ; then, as small portions of the arches on that view
could only be seen, and being at right angles to the magnetic
meridian, they would not, in the whole of their visible extent,
differ sensibly from a great circle; and Captain Kater says he
traced the one of the 29th September 1828, to coincide nearly
with a great circle. The problem of determining the height
of the aurora from one observation, by considering it as an arc

26 Mr Potter on the Aurora Borealis.

of such a circle, depends on the possibility of the solution of this

question from the following data: A plane being tangent to a
given sphere, given the angular bearings from the point of tan-
gence, of the points where a circle concentric with the sphere cuts

the tangent plane, and also the angular elevation of the highest —
point of the circles to determine its radius; the most moderate .

knowledge of mathematics suffices to tell us that no such twocir-
cles can, on the same side of the pointof tangence, appear to coin-
cide exactly in all points. Let K AM, in Plate IT. Figure 6 of
last Number, be the portion of a sphere to which the plane
Y A X is tangent at the point A, let the centre of the sphere
be the origin of the co-ordinates, let the plane of w # be in the
magnetic meridian, and the plane of ay parallel to the tangent
plane; then C BD, being an arc of a great circle, we have
given the radius of the sphere (7,) the angular bearing of the

highest point of the arc B.A X, which is in the plane of # x,

(let the trig. tang. of this angle equal e,) and theangleD A X
in the tangent plane, (of which let f equal the trig. tang.,) let
the equation of the plane in which the great circle is, be ~=wa,
then, if we have sufficient data to find the value of w, the cir-
cle is clearly determinate, but we have in the plane of # x the
following 7 =us,s=Pr + ea, and 2 + 3? = R’, where R
is the radius of the great circle; and for the points where it
cuts the tangent plane, whose equation is x’ = 7, we have
a =ur,y =fa', anda? + y'* + x? = R’, or seven equations

to determine seven unknown quantities, or eliminating a, %, 2’,

' : ; 2
7, x, and R, we arrive at this equation, Maa adi + u
a aT aed 2 or substituting for w its value — we
fi 3 a’? vr 59 5 +f* ;
may ne it under this ns a> — a2 7 — — 2 af ie ong

~ of which equations will, of course, produce shiec-wiil
real or imaginary, for « and x. Now, on the afternoon of the
26th December last, the sky became very regularly covered at
. distances with stratus clouds, and though some had very small
apparent altitude, yet the whole appeared to meet almost to-

gether in two opposite points of the horizon. If we take an

Pipa ee i

~

Mr Potter on the Aurora Borealis. 2%

example and suppose that a cloud, or an arch of an Aurora,
which was a portion of a great circle, for an elevation of 30°
in its centre, extended 170° on the horizon, we find by the
above formula that such an object, taking the smallest value
of « which the formula gives, must be at rather more than 20
miles in height to fulfil the conditions; but the arches of the
aurora are never observed to have so flattened a form as this;
and when we apply the formula to actual observations, the
height comes out so great as to be quite improbable. And,
speaking from recollection only, I believe that two arches which
I have seen had so much apparent curvature, or had so little
extent on the horizon, compared with their altitude, that when
I attempted calculations for them, on the supposition of their
being arcs of great circles, the three values for w came out
quite imaginary; and such as were impossible to be constructed
geometrically. Hence this supposition must be abandoned.
From all we know of the magnetic variation at present, it is
more probable that Mr Dalton’s supposition, (Meteorological
Essays, page 181,) that the arches are similar to parallels of
latitude -around the magnetic pole, is much nearer the truth
than the former supposition. On this ground the problem is
equally determinate with the other, or we may say more so, as
we shall find that only one such small circle can fulfil the con-
ditions required from the data; whereas in the other, there
are, real or imaginary, three values for R. It will be easily
seen by any one acquainted with analytical geometry, on re-
_ferring to Figure 7, that in this case we have the following
equations, s = r + ¢a, w? + s? = R’im the plane of wz and
y¥ =fx, uv? + yy? + x” = R’ in the tangent plane, having
2’ = r for its equation. And also, as we consider the arch
a portion of a small circle in a plane perpendicular to the sup-
posed magnetic axis, we have (w — a)? + (x —c)? = R®,
and (a — a)? + y® + (x —c)? — R”, taking R’, the radius
of the small circle considered in its own plane, where we have
nine unknown quantities, and seven equations; but if we
take g equal the trig. tang. of the complement of the mag-
netic polar distance of the place of observation A, or of
the angle, M O 2, we establish the following conditions,
e=agand a? + c? + R”? — R? and the whole of the un-

28 Mr Potter on themAurora Borealis,

known guantities may be determined. In the course of the
elimination it is convenient to put /—14+4//?, m= 1 +,

n= 1+ 9%, and p= 1 + cg, and we find the value of a for |

the particular case of each arch to come out this. eile! ex-
gpl—gm+2ep

pression, a — r ( pF pa

a has only one value for each position of the arch, or fulfilling

the same data. From this value of a we easily find those for

241
a ise 0
ce, vw, # and R, as we havec=ag,a”= = and

, @+82—re,

A 4 With these we easily find the height

of the arch. Taking as example e = tng. tang. 10°, and
SJ = trig. tang. 40°, and making g in round numbers = trig.
tang. 50°, we bring out the height of such an arch to be 276.7
English miles.

I am myself convinced that there is a very great distance
between the limits in height at which arches may exist, and
this will be seen by any one who notices the different apparent
curvatures which they take for the same angular elevation ;
but I have a very singular observation, which goes to show
that the same arch may descend nearer the earth. On the

|, which tells us that :

9 ta _—

evening of the 20th February 1830, about half-past 11 o’clock, |

I saw that there was an arch of an aurora ;. and, from a bright
mass beneath its eastern extremity, there arose several stream-
ers, which appeared to pass through the arch, and ascend toa
considerable height above it, say to 30° altitude. The air was
very cold and frosty, with a north-west wind and clear sky. It
was very clear underneath the arch, though at first there were
some small and very black clouds, which assisted me in deter-
mining the elevation. At half-past 11 the altitude of the un-

der edge was very near 15°, and the breadth of the arch 5°, !

A little before 12 o’clock, I estimated the height again, pa
called it only 12° to 15°, which made me suspect that I had
before called ittoo much. A little after 12 o’clock the arch

became very distinct and uniformly bright, and its under edge

along the whole part, which I could see,—namely, from about
the magnetic north-eastward, was quite distinctly defined, and
the light appeared to be glowing off uniformly along the whole

Mr Potter on the Aurora Borealis. 29

extent of the upper edge without the appearance of a single
streamer. The altitude during its brightest and best defined
_ period was 10° to 12°. It then became gradually fainter, and
its altitude kept decreasing. At 6 to 8 minutes past 12, its
altitude did not exceed 10°. It then became very diffuse in
the magnetic north, and at 15 minutes past 12 it was dying
away very quickly, its altitude only 5°, and still no appearance
of streamers from it. Now, as they are said never to proceed
from the south towards the north, but the reverse, and as this
arch was in the northern part of the heavens, its decrease in ap-
parent altitude could only arise from a real decrease in its height
from the surface of the earth.

One of the most brilliant displays of the aurora we have
had visible here was the one on the evening of Christmas day,
(for unfortunately the sky was obscured by clouds during
that of the 7th January, which was so fine a one to the inha-
bitants of the south of England ;)' and though the moon was
shining brightly, and only about four days from the full, it
was by far the most brilliant and extensive that I have seen:
I was told about 40’ past 6 that an arch of an aurora was vi-
sible; at about 10’ to '7 it was regular and well-defined, pas-
sing a little below the pole star ; about 15/ afterwards its under
edge was higher than « Polaris, and at the western extremity
it passed about 6° to the south of « Aquilz, counted on the ho-
rizon ; its eastern extremity was diffuse and not so well-de-
fined ; about 7 o’clock another arch had formed at about 15°
of elevation, y Ursz Majoris being in its under edge ; about
10’ after, the next star in the tail of the Bear was in its under
edge, or its altitude was about 20°, at which position it re-
mained during the display ; its under edge passed about 5° to
the north of « Agui/e counted on the horizon. The higher
arch disappeared and reappeared several times; when, at its
most southern position, it passed very near the zenith, Capella
being in its southern edge, and the more remarkable stars in
Cassiopeia being covered by it; it appeared about 6° to 7°
broad, and no part of the aurora passed farther to the south
than this arch, excepting, perhaps, a few streamers, which shot
past its western edge towards the point to which the south pole
of the dipping needle tends, so that it will form a good object

80 Mr Potter on the@Aurora Borealis.

for trigonometrical computation to those who have observed it —
at some distance from Manchester, on the same magnetic me- |
ridian. The place at which I observed it is about 13 miles to |
the north of Manchester.

These two arches were very regular and symmetrical, said
to the sight evidently very nearly at right angles to the mag- —
netic meridian ; but between them there occurred a profusion —
of irregular bands of light, taking different fantastic forms. —
Often they appeared like loops, turning again on themselves; —
at other times they appeared of a waved form, like a ribbon ©
thrown down at random. ‘These bands were generally from —
4° to 5° broad. They appeared to proceed from an immense —
mass of nebulous misty light in the north-east, and, when they —
had extended along the northern horizon, they appeared to
light up at their eastern end, and dissipate in streamers and —
glowing masses, the lightmg up proceeding onwards towards —
the west. When dissipated, other fresh bands of different
forms proceeded in the same manner from the eastern maga-
zine, if I may so call it, and were dissipated in like mannerin —
their turn. A succession of these phenomena occurred during
two hours. At 9 o'clock the aurora was dying away very
quickly. About 7 o’clock the western end of the higher arch

became of a fine bright ruby red, which continued for some
time. Many of the streamers near that end also were of the
same tint, and some were red on their western edge, and shad-
ing into yellowish green on the eastern. Though the two
arches, between which the other phenomena appeared, were
symmetrical and at right angles to the magnetic meridian, yet
these irregular bands seemed as if less under the same influ-
ence ; for, though the whole might pass in the direction of the
regular arches, yet parts of then were seen extending in re
tions at all angles to the meridian.

The arch which was visible on the evening of the 12th De.
cember last was observed by John Blackwall, Esq. of Crump-
gall Hall, about two miles north of Manchester; and I am
indebted to him for the following particulars :—‘“ On the even-
ing of the 12th December 1830, at 85 15/ p. m. a well-defined
arch of an Aurora Borealis suddenly succeeded to a splendid
display of streamers, which were lighted up from east to west,

Mr Potter on the dutora Borealis. 31

and west to east, alternately. At 20’ past 8 the vertex of the
arch attained an elevation of about 15° above the north-western
horizon, from which it did not deviate while it continued visi-
ble. ‘The arch was about 5° broad, and was bisected by the
magnetic meridian. Although the sky continued perfectly
cloudless prior to 10 o'clock, this was the only arch seen, and
there was not the slightest appearance of an aurora in any
other part of the heavens.” This arch was observed also by
Dr Burney of Gosport, to whom the world is indebted for so
many valuable meteorological observations. He says, in the
Philosophical Magazine, that at the time he estimated the alti-
tude at 8°; but having written to him to know if -he meant
this for the upper or the under edge, I am favoured by his
reply, stating, that, on further consideration, he thinks '7° for
the upper edge might be nearer its altitude, as he only esti-
mated it hastily to be about 8° at half-past 8 o'clock.

Though these low arches are not the most desirable for
trigonometrical computations, yet this has the advantage of
having been for a long time stationary, and Gosport and Man-
chester are very nearly on the same magnetic meridian. Where
we do not estimate nearer than whole degrees, we may disre-
gard the effect of refraction ; and, calling the chord of the arc
of the meridian, between the places of observation, 193 miles,
and adding 1° 23’ to the altitude at the former place, and sub-
tracting the same quantity from that at the latter, on account
of the effect of the curvature of the earth, we find the distance
of the highest point of the arch from Gosport to have been
498 miles if its altitude were 7°, or 615 miles if 8°, and its
elevation above the surface of the earth 99 miles in the former
case, and 134 in the latter.

The arch which was seen on the 29th September 1828, at-
tained at Gosport an elevation of 70°, or about 20° above « Po-
laris. With me it was visible south of the zenith, and was in
quick motion during the whole time I saw it. It passed over
8 Pegasi at about 15’ past 8 o’clock, and, when its northern
edge was about 5° south of that star, it was become hardly
perceptible. Its breadth was very nearly 5°. Hence its low-
est apparent altitude may be taken at 54°, or, if Dr Burney
only gave its altitude of 70°, whilst still of considerable bright-
ness, we must allow an altitude of 60° for its southern edge at

82 Mr Potter on the Aurora Borealis

Manchester. ‘These being corrected for the curvature of the .

earth, give the real elevation as from 197 to 218 English miles.

If we examine the arch of the 12th December by the for-
mula for a small circle around the magnetic pole,—as the
eastern end was observed to cut the horizon near the Lion’s neck,
and « Aquilee was in its upper edge in the western horizon,—
it must have had an extent in azimuth of about 115° for its
under edge, and its altitude was found for the same edge to
be 10°. On these data we find the value of w to be 350.56
English miles, and that of 2’ to be 421.67, and R — 7, or its

height 77 miles, taking the magnetic polar distance of Man-

chester at 41°, which it appears to be nearly, calculating
from Captain Parry’s observations on the position of the
Pole. Then for the upper edge we have to add the
breadth of the arch, which we find to be 31 miles, and the
height is 77. + 31108 miles,—a quantity agreeing as well with
the trigonometrical computations as we can expect, when we
see that the data are furnished only in round numbers. The
arches seen on the 25th December were too diffuse on their
eastern ends for noticing the stars they passed near ; but, cal-
culating from the magnetic north to their western end, I see
that they had less proportional extent in azimuth to their alti-
tude than the one calculated above, and so venture to predict,
that, if sufficient observations have been made for trigonome-
trical computations, that aurora will be found to have been at
a higher elevation than the one of the 12th December.

These confirm the former calculations of Mr Dalton bd
others, by assigning a great elevation to this meteor; but I
consider this as a secondary consideration to that of proving,

when we have correct measurements with divided instruments, ©

the extent of conformity with small circles (or say rather cy-
lindrical rings,) round the pole, or the extent of the deviation
from them. This involves the important subject of the mag-
netic variation and dip, which we should leave no means of 1 in-
vestigating unexplored.

It will be seen that we are not tied to the angles of the nb
where the arch cuts the horizon, but may take them at any
other elevations with proper instruments ; and by substituting,
in place of the eyuation of the tangent plane, that of any other

given plane passing through the place of observation, we shall _

Mr Taylor on the respiratory organs and Air-bladder, &c. 33

obtain a similar formula. It will be seen, that, if an arch of
10° elevation and 115° extent be 108 miles high, we must see
about 850 miles of its inner edge; and a much greater length
of its outer edge; and we may entertain a hope, that, being
on such a scale, something important may be learned on the
electro-magnetic theory of the earth, by comparing the calcu-
lated curvature with the various theories.

SmepLey Hatt, Feb. 15th 1831.

Art. [V.—On the Respiratory Organs and Air-Bladder of
certain Fishes of the Ganges. By J. Taytor, Esq. *

Awmonce the peculiarities of internal structure in the fishes of
the Ganges, the most remarkable, in a physiological point of
view, are those connected with the organs of respiration and
the air-bladder, in certain species of the genera Ophiocephalus,
Bola, Coius, Trichopodus, Macropteronotus, Pimelodus, Silu-
rus, Mystus, and Clupanadon.

The Macropteronotus Magur, Coius Cobojius, Trichopodus
Colisa, Ophiocephalus Gachua, and Silurus Singio, present, in
addition to the usual number of gills observed in osseous fishes,
certain respiratory organs, which admit, it would seem from
the tenacity of life possessed by these species, of a higher de-
- gree of oxygenation of the blood than is effected by means of
common branchie.

Macropteronotus Magur. This species (the Silurus Batra-
chus of Bloch) possesses, in a deep cavity on each side of the
head, two arborescent branchiz, similar to those discovered by
M. Geoffroy, in the Si/wrus Anguillaris of the Nile. These
organs supply the place of the superior or cranial limbs of the
two middle arches, and consist of two vascular trunks, that
spread out into numerous small branches, resembling a tree
destitute of foliage, or rather a corroded preparation of the

* Mr Taylor has been so kind as to transmit us a copy of this paper
previous to its publication in India, and has accompanied it with a series
of beautiful coloured drawings illustrative of his inquiries. _ We regret that
these cannot be given in a periodical work.—Evp.

NEW SERIES, VOL. v. NO. I. JULY 1831. Cc

34 Mr Taylor on the Respiratory Organs. and Air-bladder

kidney: they are composed of a smooth semitransparent sub-

Stance, apparently possessing the properties of the arterial tis-
sue, and are of a deep red colour, their external surface being
extensively covered by the minute branches of the branchial
artery. The aerated blood appears to be imbibed from. the
extremities of these branches, through innumerable villi in the
parietes of the respiratory ramifications into their internal ca-
nals, and thence flows into the small vessels that unite to form
the aorta. Cuvier assigns to these organs, the double function
of affording a surface for the oxygenation of the blood, and of
acting as so many hearts for propelling it into the aorta, _

— Coius Cobojius, and Trichopodus Colisa. . Each of the bran-
chial arches in these fishes, consists only of one osseous portion
or limb, and is provided with very short cartilaginous laminee;
the fourth or posterior arch presenting merely a rudiment of

that structure. . The supernumerary organ of each side lodged

in a cavity, as in the M, Magur, and supported upon a broad
stalk of cartilage, which is fixed above, by a tendinous process,
to the side of the cranium, and below, to the ends of the first
and second arches, is concealed from view, by a thin membrane
that extends across from the bone corresponding to the clavicle
and the superior extremities of the branchial arches, to the in-
_ternal side of the operculum. It consists of several broad but
very thin cartilaginous plates of a convoluted figure, intimately
connected at their bases, and so arranged as to present the ap-
pearance of a rosette. ‘Che branchial artery and aortic vessels

are ramified upon a thin membrane, reflected from the laminge.

overthe surface of this foliated organ, giving it a deep red colour.

Ophiocephalus Gachua. The branchial arches of this spe-
cies have also very short laminz. The supernumerary organ
of each side is divided into two portions supported upon two
broad osseous plates, one projecting from the internal side of
the articular bone of the head, and connected with the cornu
of the os hyoides; the other, articulated with the anterior
branchial arch, the superior limb of which is wanting, ‘The
substance composing the organ is situate upon the edge of
these plates, and consists of a thick solid tissue, having a curled

margin, not unlike that of the common species of alga, or sea- 4

weed. The branchial artery having given off branches to the
laminee of the arches, runs for a short. distance in a canal of

ee ee ee

0 Wo, ee ee ee a ee eee

of certain Fishes of the Ganges. ‘ B5

the osseous plate, which.is connected with the anterior arch,
and afterwards proceeds upon its surface, where it divides and
subdivides into: minute branches, distributed to the tip of the
supernumerary organ; the vessels that return. the aerated
blood unite into one branch, which joins those proceeding
from the gills to form the aorta.

| Silurus Singio. Besides the eight branchial arches, there
are in this fish two respiratory canals, which extend along the
back from the cavity of the mouth to near the end of the tail,
where they terminate in blind extremities. They are situate
below the superior or dorsal portions of the lateral muscles,
one on each side of the vertebre, close to their spinous pro-
‘cesses ; and are composed of two coats, of which the internal
one is smooth, vascular, and of a thin delicate texture, resem-
bling the membrane that covers the branchial laminz. Each
of these canals is provided with a large vessel, which injection
shows to be a continuation of that branch of the branchial ar-
tery sent to the posterior arch. It runs.along the bottom of
the canal, giving off, as it proceeds to its posterior extremity,
numerous transverse branches that are minutely ramified upon
its internal surface. The canals open into the mouth ; but the
communication between them and that cavity, is in a great
measure shut up by the lamine of the second and third arches,
at the junction of their limbs: these lamine are disposed in a
semicircular figure, and are so placed, in relation to each other,
as to present, when the two arches are approximated, a lami-
nated surface of an oval figure, to the mouth of each canal.
The air contained in these cavities is apparently separated
from the water, by means of the laminated body; and the
blood, thus oxygenated upon their internal surface, is convey-
ed by small vessels that descend between the transverse tig
cesses of the vertebrze, to join the aorta.*

All the species, possessing these supernumerary organs of
respiration, are very tenacious of life; surviving the infliction
of severe wounds, and living upon land for a much longer time
than other fishes. ‘* In China, the species of the G. Ophioce-
phalus,” according to Hamilton, ‘ are often carried alive in

* Ifa quill, open at both ends, be introduced through an incision, at the
side of the spine, into one of these canals, bubbles of air will arise from it
simultaneously with those disengaged from under the operculum.

36 Mr Taylor on the Respiratory Organs and Air-bladder

pails of water, and slices are cut for sale as wanted, the fish
selling dear while it retains life, while what remains after death
is considered of little value.” . The Coius Cobojius can be kept
alive without water for five or six days, and, according to thé
same author, is often conveyed in that state to the Calcutta
market, from marshes at the distance of one hundred and fifty
miles. This species, and the Ophiocephalus Gachua, like the
Doras Costata or hassar, Dr Hancock’s Zoological Journal,
No. xiv., possess the power of locomotion on land to a consi-
derable extent ; and are the fishes so often met with, after a
shower of rain, in fields at a distance from rivers or marshes;
and hence supposed to fall from the clouds:—Hamilton’s a
count of the Fishes of the Ganges, p. 68.

The air-bladder of fishes is generally found in the ancy

adhering to the lower surface of the spine. In the Ophioce-—

phalus Marulius and Gachua, however, it is not confined in its
situation to that cavity, but extends as far as the extremity of
the tail, more than two-thirds of it being enclosed between the
caudal portions of the lateral muscles. It is of a cylindrical

shape, and is divided internally into unequal cavities, by a

transverse septum, formed by a reflection of the internal coat ;
in the centre of which septum there is a small foramen sur-
rounded by a number of short radiated fibres, apparently of a
muscular structure, allowing the air to pass from one compart-
ment to the other. The external tunic, at the anterior or ab-
dominal extremity of the organ, is apparently of a muscular
texture, and is provided with a large nerve, derived from the
eighth pair; but behind it is thin and weak, the powerful late-

ral muscles. by which it is encased supplying its want of mus-

cularity.
The same kind of internal division exists in this aivabiplidil
of the Macrognathus Armatus. In’ both of these fishes, the

vascular body which, it is generally supposed, secretes the air |

’ of the bladder, is situate on the internal surface of the anterior
portion of the organ, and consists of several small meer 2
ed glands, with. minute villi diverging from them. tid
In the Coius Cobojius it extends also as far as the end of
the tail. Behind the bone that forms the boundary of the ab-
dominal cavity, it is divided longitudinally by the spines. that
support the anal fin, into two cavities: strong tendinous fibres

’

<—— ee a

“a

of certain Fishes of the Ganges. 37

run obliquely between these spines, and fill up the space be-
tween them, leaving merely a few irregular openings of com-
munication between the two sides above and below. ;

‘In the T'richopolus Colisa it differs from that of the former,
in having a membranous septum in its abdominal portions ;
thus dividing the organ into two Com par tineanany from one ex-
tremity of it to the other. aa

~The air-bladder varies considerably as to figure, size, and
internal structure, among the species red the ers Pimelodus
and Silurus. — |

In the P. Aor it usually consists of two portions of the figure
of a heart placed ina line, and united at their apices.

It is extremely small in the P. Silondia in proportion to the
bulk of the fish. It lies close to the anterior vertebra, is of an
oval figure, and is divided into two cavities, each of which, ina
fish weighing eight pounds, is not larger than a hazel nut. |

The P. Pangasius has it composed of four or more portions,
extending in a line from opposite the pectoral fins, to near the
end of the tail. The first is generally oval, the second pyra-
midal, and the two last, which run between the caudal portions
of the lateral muscles, approach to a cylindrical shape. The
numerous septa on its internal surface descend from above
downwards in the first portion ; in the second, they run in a
transverse direction ; and in the posterior ones, form a number
of irregular cells.

In the Silurus Boalis it is of the figure of a heart, divided,
internally, by a longitudinal septum into two cavities, which
have a free communication with each other through a semilunar
opening at the anterior part of the septum.*

It communicates in all of these species with the alimentary
canal, by a ductus pnewmaticus, extending from its lower sur- -
face to the cesophagus.

The air-bladder, besides possessing the locomotive function
generally ascribed to it, appears, from the connection that ex-
ists between it and a set of small bones, analogous to the ossicula
auditus, to exert some influence on the sense of hearing.
These bones correspond to the malleus, incus, and stapes of
Mammalia, and are present, according to Professor Weber, by

* This cavity generally contains a number of worms of the G. Fasciola.

38 Mr Taylor on the Respiratory Organs and Air-bladder

whith they were discovered, in all the osseous fishes, in the vi-.
cinity of the anterior or cervical vertebrae. —(Blumenbach’s Com-.
parative Anatomy, p. 285.) They exist in the different species of

the genera Silurus, Pimelodus, and Cyprinus, I have had an

opportunity of examining; but are apparently wanting in the
genera Ophiocephalus, Cotus and T'richopodus : and also in the:
Bola Pama, Mystus Chetala, and Clupanadon Ilisha, in which

species their place is supplied by a direct connection between the

twoorgans. The bone corresponding to the malleus is consider-
ably larger than either of the other two, and is uniformly si-.

tuate at the anterior extremity of the air-bladder, extending
along the side of the spine to opposite the first vertebra. In
the Silurus Boalis its anterior half is long, flat, and of a tri-
angular shape, terminating in a blunt point, while the posterior
portion is crescentic, having below a scabrous surface, to which
the external coat of the air-bladder is firmly attached. By
means of a short styloid process, projecting from the side of the
latter portion, and received into a pit on the body of one of
the vertebre, this bone enjoys a limited degree of lateral motion,
by which its apex can be made to approach or recede from the
spine. The ineus, which is of a short cylindrieal shape, is
placed between the apex of the malleus, and the bone corre-
sponding to the stapes, and at aright angle with the former: and
is attached to each of these bones by a short round thick ten-
don, in the centre of which it presents the appearance of being
imbedded. The stapes may be described as consisting of two
parts: one is a thin hollow portion, of an oval figure, somewhat
resembling the bowl of a spoon, having the tendon of the incus
attached to its convex side; the other consists of a small round
knob, with a minute spicula projecting from it, and is joined by
a neck to the small end of the first portion. It is situate in a
large foramen in the first vertebra, and forms one of the sides
of a small chamber communicating with the cavity of the cra-
nium. This chamber lies immediately behind the cavity con-
taining the sac and ossicula, or calcareous bodies of the inter-
nal ear; and within the canal of the first vertebra, its roof
being composed of a strong tendinous membrane, that supports
the medulla spinalis above. ‘The oval portion of the stapes,
with its concave side presented towards the interior of the
chamber, is loosely connected by a membrane, to the edge of

aoe SS hes

of certain Fishes of the Ganges. 39

the foramen, and admits of being projected into it, to such an
extent as almost to touch its fellow of the opposite side, when
both mailei are at the same time gently depressed with the
finger, upon the ineudes. The anterior portion of the malleus,
and the incus with its tendon, as far as its attachment to the
stapes, are inclosed in a tendinous sheath, containing a quantity
of gelatinous fluid: they have no muscles attached to them,
and it is probable, therefore, that the slight motion which the
malleus enjoys, through the medium of its articulation with
the vertebra, is entirely regulated by the external coat of the
air-bladder.

The air-bladder of the Pimelodus Gagora, Pimelodus Bag-
haria, Silurus Singio, and Macropteronotus Magur, is placed
behind the head, close to its articulation with the first vertebra,
and in this situation is connected with the osstcula auditus,
which are conspicuous, and present the same relative position
as those of the Stlurus Boalis.

In the P. Gagora there are two air-bladders lodged, one on
each side, in an osseous cup attached by a narrow neck to the
body of the first vertebra, close to its junction with the cra-
nium. The mouth of each of these cups is covered over by
the common integuments, which are at this part extremely thin,
and adhere to the surface of the subjacent bladder, presenting,
when the latter is distended with air, an external elastic tumour,
of an oval figure.: The two air-bladders, which have no com-
munication with each other, or with the alimentary canal,
apparently derive their supply of air from a vascular tissue, -
placed between the two cups where they are attached to the
spine: the external coat is of a thin texture, and argentine
colour, and has a layer of fine adipose substance interposed be-
tween it and the internal surface of the cup.

The P. Bagharia has also two air-bladders, which closely re-
semblethe former in the argentine tendinous texture of the exter-
nal coat, and in having no communication with each other, or
with the alimentary canal. They are situate, one on each side
of the body, in a deep groove or furrow of the consolidated
transverse processes of the cervical vertebree, and are extreme-

_ly small, in proportion to the bulk of the fish; each of them,
in an individual weighing ten pounds, not exceeding a large

40. Mr ‘Taylor on the Respiratory Organs and Air-bladder |
garden pea in size : they are placed at the middle of the grooves,)
at about an equal distance from the common integuments (im-: ,
mediately behind the pectoral fins) and the vertebral column;
the space between each of them and the former being filledup
with adipose substance, while that next to the spine is occupied ;
by the malleus. » og
In the Silurus Singio and Macropteronotus Magur, the air-
bladder consists of two small pyriform bags, joined at their’
pointed extremities by an intermediate canal. It is situate
across the spine; each of the pyriform portions being contain-
ed in a funnel-shaped case, projecting outwards from the side
of the body of the first vertebra, and having its mouth cover-
ed over by the common integuments, as in the P. Bagharia.
The case is formed of bone above, and below by a tendinous
membrane that extends across the inferior surface of the first
vertebra, thus protecting from pressure the intermediate canal
or isthmus by which the two pyriform portions are united. A
communication exists between it and the alimentary canal, by
a small ductus pneumaticus from the intermediate canal tothe
cesophagus. | )
In the Bola Pama, Mystus Chetala, and Clupanadon Ilisha,
there exists a more direct connection between the air-bladder
and organ of hearing, than through the medium of the a
bones above referred to.
The air-bladder of the Bola Pama is of a pyriform sleaths
terminating behind in a slender elongated process. From each
side of this process an appendix arises by a minute origin, and
proceeds by the side of the body of the bladder, gradually en-
larging in size, until it reaches its anterior extremity, opposite
to which it divides into a number of blind tortuous branches,
that spread out upon the lower surface of the kidney. Two of
these branches, which areconsiderably larger than the rest, follow
a very singular course : one mounts over the bone corresponding
to the clavicle, and appears externally under the thininteguments
at the edge of the apertura branchialis ; while the other winds
round the cavity in which the internal ear is lodged, and almost
meets its fellow of the opposite side, at its anterior part. ‘This
latter branch, (the one connected with the organ of hearing,) is
dilated at its extremity into a conical shaped bag, which is of
a very thin delicate texture, and is placed in a small pit or fossa

of certain Fishes of the Ganges. . 4d

on the external surface of the base of the cranium, having mere-
ly a thin septum, generally of a membranous nature, interposed
between it and the principal ossiculwm, or calcareous body of
the internal ear.

Inthe Mystus Chetala this organ extends in length from the
first vertebra to near the extremity of the tail. ' Anteriorly, it
forms several chambers communicating with each other, and
behind is divided into two parallel cavities by a longitudinal
septum, which, like that of the T'richopodus Colisa, is partly —
membranous, and partly composed of the spines that sustain the
anal fin. ‘These spines are long, hollow, cylindrical bones, and
are connected by the internal lining coat of the bladder, reflect-
ed on both sides over their whole extent of surface. The la-
teral muscles forming the walls of the cavity are very thin, and
send off from their lower part small slips of muscles that are in-
serted into the membrane between the spines, by which means
the septum can be expanded somewhat in the manner of a fan.
A free communication exists between the two sides of the organ,
through a number of foramina in the membrane connecting the
spines, and anteriorly between one of the chambers and the
cesophagus, by means of a round opening, wide enough to admit
the point of the little finger. From the anterior part of the
organ a canal proceeds upon the inferior surface of the cranium,
as far as the cavity containing the internal ear, opposite to
which it terminates in a blind extremity. It consists of a deep
furrow on the external surface of the base of the cranium,
covered below by an elongation of the external coat of the
bladder, (bearing some analogy in its structure to the Eusta-
chian tube of the higher orders of animals ;) and like the cor-
responding part in the Bola Pama, is separated from the prin-
cipal ossiculum of the internal ear, by a septum so thin and
delicate that the slightest touch with a pin is sufficient to rup-
ture it. (See Note A.)

The air-bladder of the Clupanadon Ilisha is long, narrow,
and pointed at both extremities, as in the genus Clupea.
From its anterior extremity two very minute ducts arise, and
proceed along the inferior surface of the cervical vertebrae and
posterior part of the head, to terminate in two small air-bags,
situate one on each side of the cranium. These ducts, when

42 Mr Taylor on the Respiratoyy Organs and Air-bladder

divided with* the knife, present open mouths, scarcely large

enough to admit the point of a fine bristle : they are semitrans-_

parent, and bear a striking resemblance, both in structure’
and appearance, to the membranous semicircular canals of
the internal ear. The small bags to which they lead, are
lodged in two cavities of a corresponding size in the substance:
' of the osseous walls of the cranium, in which situation they

are entirely concealed from view. Each bag may be describ. |

ed as consisting of two portions: the first has a horizontal po-

sition, and somewhat resembles a French bean in figure; the

second is pyriform, is situate above the first portion, and is

united to it at nearly a right angle. These bags have very _

thin septa interposed between them and the ossicula of the in-

ternal ear, and differ considerably in texture from the organ

in the abdomen ; their external tunic being thin, and of a sil-
very appearance, while that of the latter is thick, and of a
dark red colour, preseuting a smooth internal surface, ite
that of a serous membrane. |

§ On the Anatomy of the Cuchia.
The Cuchia, an animal generally regarded as a species of
eel, is entirely destitute of fins, and presents, in the structure
of its organs of respiration and circulation, some remarkable
peculiarities, which would lead us to place it between the class
of reptiles and that of fishes. It is common throughout the
south-east parts of Bengal, especially in the vicinity of D’haca,
where it is generally found lurking in holes and crevices on
the muddy banks of marshes and slow-running rivers. Ha-
milton, viewing its single external spiracle or branchial aper-
ture below the throat as a generic character, has assigned a place
to it under the genus Unibranchapertura of Lacepede, (the ge-

nus Synbranchus of Bloch,) and has given an accurate descrip-

tion of it in his excellent work on the fishes of the Ganges
(See Note B.)

Organs of Digestion. 'The alimentary canal is pric" 4

in a straight line from the mouth to the anus, and measures
about three-fourths of the whole length of the body. The
eesophagus is considerably longer than in the eel or fishes in
general, and presents internally, longitudinal folds of a white

of certain Fishes of the Ganges. AS

colour. The stomach, which is slightly dilated at its middle,
is distinguished from the former by its more muscular parietes,
and the red villous appearance of the internal lining coat : to-
wards the pylorus, where it is separated from the intestine by
a valve, it is contracted in diameter, and is of a white colour.
The latter part of the canal exhibits upon its internal surface,
short villous processes, arranged in a zigzag manner, and is
_ divided by an annular projection of the internal coat into two
portions, of which the last (or the part corresponding to the
rectum,) although shorter, is considerably more capacious than
the anterior or duodenal portion. The liver is of a narrow
elongated figure, attached to the side of the stomach, and has —
several deep transverse furrows upon its inferior surface: the
gall-bladder, which is of an oval shape, lies near its posterior
extremity, on side next to the stomach, and sends out a long
cystic duct, that opens upon the internal surface of the intes-
tine, immediately behind the pylorus. . There is a long chain
of small quadrangular shaped spleens, covered by a thin re-
flection of the peritoneum, and joined at their bases to a blood-
vessel of considerable size, which extends throughout their
length by the side of the intestine.

Urinary Organs. , The kidneys, as in fishes, are long nar-
row glands, of a dark colour, running along the side of: the
vertebral column, and closely attached to it, as far as the an-
terior extremity of the abdomen. The bladder is of an elonga-
ted shape, and receives the secretion of the kidneys by two
ureters opening into it at its fundus.

Organs of Generation. 'Those of the male are two long
ducts of a greyish colour, possessing a number of lateral tor-
tuous branches, that adhere to the external surface of a part
of the first portion of the intestine. In the female there is a
single pyriform ovarium, containing numerous ova, of various
sizes and colours, apparently in different stages of fecundation ;
and hence it may be inferred that the animal is viviparous.
They terminate along with the urinary organs in a common
cavity, the external outlet of which lies immediately behind
the anus. The air-bladder is wanting.

Bones. The cranium is articulated with the first vertebra
by two occipital condyles, one on each side below the foramen

44 Mr Taylor on the Respiratofy Organs and Air-bladder

magum, and also by a single tubercle of the body of the ver-
tebra, as in the osseous fishes. The bones entering into the
formation of the mouth resemble those of fishes. The supe-
rior maxillary one is long, slender, and of a curved figure,
having its convex side presented outwards : it is joined above
to the malar bone, and below to the coronoid process of the
lower jaw. The latter consists of two strong pieces slightly
incurvated, and firmly united at their symphysis by cartilage:
each piece being formed by two bones closely wedged together.
Both jaws are furnished with teeth, the largest being planted
in the palatine arches above ; they are fixed in alveolar cavi-
ties, are sharp pointed, and of a hook form, but do not possess
any structure resembling the tubular fangs of serpents, to con-
firm the opinion entertained by the natives, of the venomous
nature of the bite of the animal. The branchial arches are
situate behind the head, at the sides of the four anterior cer-
vical vertebrae, and possess a semicartilaginous structure, ex-
hibiting, when held up to the light, several detached osseous
pieces, of an irregular figure, imbedded in a semitransparent
substance. With the exception of the first or anterior arch,
which is fixed to the end of the cornu of the os hyoides, all
the others are articulated below to their fellows of the opposite
side. The first and second are composed, each of one portion,
and are free at their superior or vertebral extremities, present-
ing the appearance of being suspended in the membrane of the
pharynx; while the third and fourth, or two posterior ones,
have very minute superior limbs, which are attached to a
small pharyngeal bone, connected through the medium of a
long and flat muscle, running between the membrane of the
back part of the mouth and the inferior surface of the verte-
bree, with the base of the cranium. All the arches are smooth
on their internal surface. The bones corresponding to the
scapulze, or those which in fishes support the pectoral fins, are
long, slightly curved, and united by cartilage at their inferior
extremities. ,
Connected with deglutition, and situate below each of the
latter, is a small bone, which, together with the pharyngeal
‘bones, is covered on the side next to the gullet, with small
teeth. ‘Ihe body of each vertebra is hollowed out posterior-

&

of certain Fishes of the Ganges. 45

ly, forming a hemispherical cavity, in which the interverte-
bral fluid is contained, and is united through the medium of
this substance, and also by a small triangular process sent off
from each side of the cavity of the medulla spinalis, with the
bone contiguous to it. The spinous process is bifurcated, or
rather consists of two distinct pieces inclining in different di-
rections ; and each transverse one, of a short thick spine, groov-
ed on its anterior aspect, with a thin plate of a triangular
figure arising from it behind, and occupying the whole side of
the body of the bone. The ribs, which are extremely small,
are attached to the points of these processes as far as the anus.
The cervical and caudal vertebre are distinguished from the
intermediate or dorsal ones: the former by the compressed
flattened appearance of their bodies, the latter by possessing
spinous processes both above and below.

Organs of Sense. 'That of smelling appears to be the most
perfect. ‘The nasal cavity of each side is tubular, and has
two apertures, an anterior one at the extremity of the snout,
and a posterior between the eyes: and consists also of two
parts, one running forwards, the other extending backwards
from the anterior opening in a duplicature of the membrane
connecting the malar and maxillary bones, as far as the point
of union between the latter and the coronoid process of the
lower jaw. The cavities of both the sides have a free commu-
nication with each other at their anterior extremities, and may
be filled with vermilion injection from one of the apertures. The
eyes are very small, and are covered anteriorly by a transpa-
rent skin. The thalami optici lie behind the cerebrum, and
send out two long slender optic nerves, which cross each other
without any incorporation of substance.

Organs of Respiration and Circulation. Upon the under
surface of the throat there is a semilunar aperture, divid-
ed below the integuments in the mesial line of the body
into two smaller openings, each of which leads to the gills of
the corresponding side. The branchial arches are connected by
a strong tendinous membrane, in which are three small open-
ings of an irregular figure for the passage of the water from
the mouth, and are covered below, for about one-third of their
length, by a thick muscle proceeding from the bone correspond-

46 Mr Tayloron the Respiratory Organs and Air-bladder

ing to the scapula to be inserted info the os hyoides. Of all
the arches, the second alone possesses laminz for the purpose
of breathing ; and these consist merely of a few long fibrils at-
tached to the middle of the arch, and occupying but a very
small extent of its surface; the third supports in the place of
lamine, a thick and semitransparent tissue, which in large in-
dividuals of the species presents a fringed or denticulated ap-
pearance at its edge, while the first and fourth are bare, hay-
ing only the membrane that fills up the space between the
arches reflected over them. ‘The principal organs of respira-
tion are two small bladders, which the animal has the power
of filling with air, immediately derived from the atmosphere.
They are placed behind the head, one on each side of the neck,
above the superior or vertebral extremities of the branchial

arches, and are covered over by the common integuments, pre-

senting externally, when distended with air, two protuberances
of around shape. . On dividing the skin, and reflecting it back,
each bladder is found to be partially covered, at its anterior
part, by a small and extremely thin operculum, joimed to the
upper part of the articular bone of the head, and connected be-
low with a membrana branchiostega, which is supported by
six osseous rays. The posterior portion of the organ extend-~
ing beyond the edge of the operculum, is confined in its situa-
tion, by a broad but thin muscular expansion, running across
it in an oblique direction, from the tendinous sheath of the
spinal muscles above, to the gill membrane below, , These
bladders, which are smooth, and highly vascular upon, their
internal surface, do not possess a laminated structure, such as
that of the respiratory bags in the lamprey ; but present, when
separated from their surrounding attachments, and inflated
with air, thin semitransparent: ‘membranous parietes resembling
the posterior portion of the lung of serpents. » Each communi-
cates with the cavity of the mouth, by a wide semilunar open
‘ing between the os hyoides and the first branchial arch ; its
Jower margin, which is thick and prominent, is composed of
several muscular fibres that extend between the end of the
first branchial arch and the side of the spine, constituting a spe-
cies of constrictor muscle, by means of which the aperture can
be contracted to so small a size, as to perform, in some degree,
6

of certain Fishes of the Ganges. ih ay

the function of the glottis, and thus produce a slight hissing
noise, as may occasionally be heard, when the air is forcibly
expelled from the bladder. ‘The heart is situate upon the in-
ferior surface of the cesophagus, close to its termination at the
stomach: and from the extreme proportional length of that
tube, is at a much greater distance from the organs of respira-
tion than is the case in fishes. It consists of two cavities, an
auricle, and a ventricle, provided with a thin membranous valve
between them. . The former receives all the blood of the body
by four large vessels, viz. two veins conveying it from the head
and anterior parts; one from the liver; and one from the mus-
cles of the posterior portion of the spine, the organs of gene-
ration, and the other viscera-of the abdomen. ‘The first run
close to the spinal column, one on each ‘side, and are joined
by a transverse branch opposite to the twelfth vertebra: they
afterwards separate, and proceed, one in a straight direction,
the other across the inferior surface of the cesophagus, to ter-
minate in the auricle. ‘The posterior cava, which is the largest
of all, proceeds along the inferior surface of the spine, between
the kidneys, to its destination; while the cava hepatica, after
piercing the pericardium at its posterior part, runs for some
distance within the cavity before it terminates m the auricle.
The ventricle is of a conical shape, of a reticulated appearance
internally, and possesses two sigmoid valves at the origin of the
branchial artery. ‘The latter arises from it by an elongated
bulb, of an oval figure, and measures from two and a half to
three inches in length. It extends along the inferior surface
of the esophagus, and divides, opposite to the posterior bran-
chial arches, into three branches of an equal size. Two of these
branches run, one on each side, between the fourth or poste-
rior arch and the small bone connected with deglutition, as
far as the vertebral extremity of the inferior limb of the for-
mer; and being there reflected backwards, unite at an acute
angle, opposite to the tenth vertebra, to form the aorta, The
third branch, which is the continuation of the artery, proceeds —
along the under surface of the arches, and gives off, in its
course, a branch to the second and third of each side; it then
runs forward as far as the os hyoides, and is ultimately expend-
ed upon the respiratory bladders. The small branches of the

48 Mr Taylor.on the Reegtratety Organs and Air-bladder

second and third arches, after supplying the laminze of the
former and the semitransparent tissue of the latter with small
twigs, are also continued to the bladders; where they are mi-
nutely ramified, forming an indistinct net-work of vessels upon
their internal surface. Fine vermilion injection, thrown in at
the root of the branchial artery, penetrates these minute ves-
sels distributed upon the second. and third arches and the in-
ternal surface of the bladders, while at the same time it fills
the aorta and its branches as far as the tail. The aerated
blood is returned by small vessels, forming, at the posterior
part of the bladders, two short trunks, which join the branches
of the branchial artery before they are reflected backwards,
and unite to constitute the aorta.

The Cuchia, it is obvious from this account of its anatomi-
cal structure, possesses the circulation of reptiles, and the re-

spiration, partly of that class of animals, and partly of fishes. .

Of the whole volume of blood contained in the branchial ar-
tery, one-third passes through the gills and respiratory blad-
ders, while the other two are conveyed directly from the heart
to the aorta, without being exposed to the action of the air.
This fluid, therefore, undergoes a partial oxygenation, present-
ing, as may be inferred, a dark purple colour in both divisions
of the vascular system, the arteries as well as the veins. Hence
the obtuseness of the external senses, and want of activity ob-
servable in the Cuchia. It is of a dull and languid nature,
exhibiting in all its movements a degree of sluggishness that
forms a striking contrast to the vivacity of the. eel. A few in-
_ dividuals, which I kept in water for upwards of two months,
during the last rainy season, were observed to lie at the bot-
tom of the vessel in a very weak and apparently torpid state,
without taking any food: and seldom moved about, except oe-
casionally to rise to the surface for the purpose of inhaling air.
The respiratory bladders, although individually of a small size,
afford, in conjunction with the branchial structure of the second.
and third arches, a sufficient extent of surface for the oxygena-
tion of the small portion of the blood transmitted to them. They
do not approach either in configuration or texture to any known

modification of branchiz, but on the contrary have a close simi-.

litude, in both these particulars, to the posterior portion of the

i

i ee <a wes

of certain Fishes of the Ganges. 49

lung of serpents. The power which the animal possesses of
distending them with air, while on land, and the necessity it is
under, of rising to the surface of the water for the same pur-
pose, prove beyond a doubt that they perform the function of
lungs; and lead us to the conclusion, therefore, that the Cuchia
is ‘* amphibious” in the strictest sense of the word,—forming a
connecting link, as it were, between the Ophidian order of rep-
tiles, and the genus Synbranchus of fishes.

(Note A.) In this species there is a cavity on each side of
the head, corresponding to the tympanum of other animals.
It is of an oval figure, and is covered externally by the com-
mon integuments, which are of a smooth shining appearance,
and destitute of scales. It is found to contain a quantity of
gelatinous fluid, and has a thin cartilaginous plate imbedded
in the latter on the one side, and attached to the portion of
skin analogous to the membrana tympani, by a small hook-like
process on the other. It leads to a small foramen on the side
of the cranium. ‘This foramen corresponds to the fenestra
rotunda of Mammalia ; and is filled up by a thick membrane
that separates the cavity of the tympanum from the ossicuwla,
and the membranous semicircular canals of the internal ear.

(Note B.) This fish I found in the rivers and ponds of the
south-east parts of Bengal. It is said to grow to two feet in
length, and six inches in circumference: but those that I have
seen were shorter and thinner in proportion to their length.
Europeans eat the Cuchia as an-eel: but the natives reject it,
and imagine that its bite is fatal to cattle, although less power-
ful on the human kind; a supposition highly improbable.
The whole form of the animal, having no vestige of a fin, re-
sembles strongly a serpent. This fish is cylindrical, devoid
of scales, and lubricated with slime. The colour above is
dark green, below a dirty pale red: on every part are scatter-
ed small round black spots, and short yellowish lines. “Two
parallel pale lines run forward from the shoulders, and at the
eyes join at an acute angle two others, coming from the sides
of the chest. Parallel to the last are two others, one on each
side beneath the lateral line. The head is blunt and of a mo-
derate size, but swells out when the animal is irritated. The

NEW SERIES, VOL. V. NO. I. JULY 1831. D

50 -Dr Hibbert on theewistence of

snout is depressed, short and retuse, projecting a little beyond
the under jaw. The nostrils are near the end of the snout,
very small, and each has only one aperture. The eyes are near
the upper part of the head, as’is also the aperture to the gills.
The lateral. line forms an arch before, and then runs straight
along the middle of the side. The tail ends in a sharp point,
is compressed, and has sharp edges above and below, apa
ton on Fishes, p. 16.

Dacca, 15th June 1830.

Art. V.—On the Question of the Ewistence of the Rein-
Deer, during the Twelfth Century, in Caithness. By 8.
Hrsrert, M. D. F. R.S. Ed. &c. &. Communicated by

» the Author. }

Tuar the Jarls of Orkney, in the twelfth century, were in
the habit of crossing the Pentland Firth to chace the rein-deer
of Caithness, has been asserted by Torfeeus: ‘ Consueverant
Comites in Catenesiam, indeq.’ ad montana ad venatum caprea-
rum rangiferorumgq.’ quotannis proficisci.”-—( Rerum Orcaden-
sium Historie, Lib. 1. cap. xxxvj.) |
Torfzeus wrote at the close of the seventeenth century, and
I long thought that in following very ancient Scandinavian
authorities, he had either misquoted his original by the substi-
tution of Rein-Deer for Red-Deer, (which last are still the
proud objects of the chace of the Chatti,) or that, m prefe-
rence to the language of the more authentic histories of the
Jarls of Orkney, he was incautiously perpetuating that of the
romantic Sagas. ‘This sentiment, which I stated many years
ago at a meeting of the Society of the Antiquaries of Scotland, —
I must now condemn, without, however, acquitting Torfaeus
of total inaccuracy. a tae
The manuscript sources whence Torfzeus drew the chief ma-
terials of his annals have been explained by a learned Icelander,
Jonas Jonzeus, by whom an abstract and Latin translation
have been subsequently published. (Hafniz, Anno 1780.)
This work I lately consulted in reference to Caithness, and I
was not a little surprised to find, that if 'Torfseus had done

Rein-Deer in Caithness in the 12th century. 51.

precise justice to his original authority, it would have been
impossible for any author of the present day to ‘suppose that
for the rein-deer we ought to read the red-deer. The passage
is as follows: ‘‘ That var sithr Jarla ner hvert sumar at fara
yfer 4 Katanes oc thar upp 4 merkr at veida rauddyri edr
hretna ;” which Joneus renders after the following manner :
“‘ Solebant Comites quavis fere estate in Katenesum transire
ibique in desertis feras rubras et rangiféros venari.”

We thus find, that instead of the Jarls of Orkney com-
ing over to Caithness to kill the rein-deer and the roe, (Ca-
prea) as'Torfzeus would have us read, the animals actually enu-
merated were the rein-deer and the red-deer, (rauddyri,) each
being supposed to exist at the same time in the north of the
Caledonian Highlands. .

The date of the period when Ronald and Harold, the two
Jarls of Orkney alluded to, visited Caithness to hunt, has
been assigned by Jonzeus to the year 1159; and as the Skalds,
who have commemorated the event in their verses, were gene-
rally accurate in their description of the objects of the chace,
no suspicion on this score can be rationally entertained. Their —
historical verses were often composed during the lives of the
heroes whose feats they recorded, and sung at public feasts ;
and it would have been ‘as derogatory to their Skaldship to
make the Jarls of Orkney kill rein-deer in Caithness, sup-
posing that no animals of the kind had then and there existed,
as for a modern bard to celebrate a tiger hunt among the red-
deer haunts of Atholl.

But the question of the degree of confidence to be attached to
this curious passage of the Orkneyinga Saga, may be best con-
signed to the critic who has shown himself familiar with the cir-

cumstances under which the Skalds composed their historical —

verses, and with their mode of composition. Jonzeus, in a note
which he has written in his indew vocum upon the word Hreinn,
(animal quod vulgo rangifer vocatur,) after several illustrations
of its etymology, adds, “ Quod maximi momenti est, evincit lo-
cus citatus fuisse tempore isto in Scotia Renones. Nec proprii
semper Gronlandis et Lapponibus fuerunt, etenim Islandia

seculo xij, teste jure Island. Ecclesiastico Thorlaco-Kettil-

liano Cap. xxxi. eos habuit. Exstirpati tamen sunt incolarum

52 Dr Goring on Monochromatic Light, &c.

incuria, qua etiam dudum periere, multo illorum damno, —
sed domestica animalia, sues, anseres, &c.”

This is an apposite remark, the interest of which is height-

ened by the analogy made use of concerning the extinct rein-

deer of Iceland.

- Unfortunately, however, for the confirmation of these re-

mote historical allusions, we have not, I believe, upon record
the account of any fossil animals of the Rangifer having yet
been discovered among the wilds of Caithness or Sutherland.
But as the extinct zoology of Britain has been hitherto i imper-
fectly studied, the objection is far from being a formidable one.
Until lately, countless bones of fossil animals have been de-
stroyed, under the impression that they were the unfit sti cic!
of any museum whatever. |

Leigh, in his Natural History of Lancashire, (Book 3d,
p- 84,) has stated, that the horn of a rein-deer was found under
a Roman altar discovered at Chester, and he has given a draw-
ing of it. But the delineation is that of a fragment only, and
its character is too indeterminate. Leigh, however, was a good
naturalist, considering the time in which he lived, and we are
scarcely warranted in roundly asserting that he was deceived.

Art. VI.—On Monochromatic Light, and on the Achroma-
tism and Spherical Aberration of Eye-pieces and Engy-

scopes. By Cuaries Gorinc, M.D. Communicated by

the Author.

hy : : : . "
Tue scheme of illuminating microscopes by monochromatic —

or homogeneous light, in order to render their chromatic aber-
ration insensible, appears in theory extremely plausible ; ne-
vertheless, there are many objections to it. In the first place,
it is evident that all sorts of monochromatic illumination what~

soever must be far less intense than the ordinary kinds, in as —

much as they must consist of one of the seven constituent pris-
matic colours abstracted from the rest ; for if a beam of light’
is divided into seven parts, and only one of them is taken,
(though it should be the brightest of the set,) it must follow
that it will be far fainter than the combination of the whole.

i - Se el

Dr Goring on Monochromatic Light, &c. 53

It is well known to practical men, that the most vivid white
light which can be procured, barring always that of the sun,
is by no means too brilliant for opaque objects ; it can need,
therefore, no argument to show, that, at all events, monochro-
matic light can never answer for these, however much it may
be condensed ; for transparent ones with low powers and large
apertures it might, were it not for some circumstances to be
hereafter stated. Monochromatic light must of course always
be of some colour or another, which circumstance, of course,
must produce a very fallacious appearance in the vision of most
objects, which will compel the observer to examine them afresh
with white light, in order to rectify their apparent tints. More-
over, I myself am convinced that a real monochromatic light
is yet to seek, and shall here state the experiments on which I
found my opinion, leaving it to others better acquainted with
the subject than myself to ascertain whether I am in error or
not. When white light is subjected to the action of a prism,
it is well known that it is dispersed or resolved into seven pris-
matic rays, leaving a number of colourless lines, when the
experiment is made with due delicacy in the method 'prescrib-
ed by Fraunhofer. Now, if there is any such thing as mono-
chromatic light, assuredly a prism ought to be able to produce
it; and, accordingly, I have chosen light so generated for my
experiments. :
The white light of the sun reflected by a plane mirror is
able to show most of the coarser proof-lined objects in a rough
manner ; indeed, I have sometimes succeeded in bringing out
the straight lines on the Podura with it, and this too with an
instrument which had not the power of showing them with any
other species of illumination. I therefore chose this class of
objects in my trials with solar light, for they are, upon the
whole, exhibited better in proportion by it than any other bo-
dies. In order, however, to obtain from the solar beam a
monochromatic illumination, I made the following arrange-
ments :—I placed a compound microscope with its body in a
horizontal position, and excluded all white extraneous light
from it as follows :—I attached a tube six inches long, to the
stage, and at the end of it fixed a diaphragm } of an inch in
diameter in the prolongation of the axis of this tube; and, at

54 Dr Goring on Monochromatic Light, &c.

about a foot distant from it, I hung up a piece of black silk
velvet. I likewise drew a shade over the object-end of the
microscope, reaching close down to the slider, so that no light
. should get into the body of the instrument by reflexion. By
these means, when its power was equal to that of a j; of an
inch lens, I could not see my field of view. I then introduced
a prism, (the edges and other parts of which not employed to
refract light were carefully blacked, that no white light might
be reflected or radiated by it,) between the piece of black vel-
vet and the tube, so as to refract the light of the sun from a
mirror into the microscope. ‘The prism was placed vertically,
so that either of the seven colours it produced could be brought
to bear upon the small aperture at the end of the tube, to the
exclusion of the rest; the spectrum being of considerable
breadth, owing to the distance of the prism from the diaphragm,
which was about three feet. Now, by this apparatus, I could
very easily select any one of the colours I wanted,:by merely
moving the microscope a little to the right or left, and illumi-
nate the object with it. ‘The object-glass which I made use
of was a plano-convex of half an inch focus, and a quarter of
an inch of aperture, which, with the white light of the sun,
was just able to show the lines upon the scales of the Menelaus
butterfly in a very imperfect manner ; and was much disap-
_ pointed and surprised to find that no amelioration in the vision
was produced by using any of the prismatic cclours instead of
the white light. Moreover, I found that not one of the colours
produced apparent achromatism, unless it truly perforated the
axis of the microscope; any obliquity of the light instantly caus-
_ ing prismatic colours to appear, modified by the tint of the co-
loured ray used, much in the same manner as white light would
have been if merely passed through a piece of coloured glass.
Now the lined objects always require oblique light for their
manifestation, and consequently, never could be shown without
exhibiting other colours. beside those of the primary ray em-—
ployed ; but other objects which agree with direct light could
be shown destitute of prismatic fringes, though very confused
and indistinct. I may observe, that the light of the sun treat-
ed in this way is by no means too intense for microscopic pur-
poses. I even thought that the violet ray was not intense

Dr Goring on Monochromatic Light, &c. 55

enough.. The blue ray, with an achromatic object-glass, per-
forms pretty well on the lined objects. I like it better than,
any of the rest, (for it most resembles day-light,) though each
is capable of exhibiting the lines, if not procured in a state of
too great intensity, by being taken too close to the prism.

_ I repeated these experiments with the flame of a wax taper
in a dark room in the following manner :—I used the prism as
before, and adjusted the wax light to a proper height to suit
it, I then carefully shaded the candle, so that none of its di-
rect light should get into the microscope, and threw the spec=
trum formed by the prism into the body of the instrument,
taking care'to use it at such a distance from the prism that
the light of the taper should be fairly dispersed. I did not
use the long tube in these experiments, thinking it of no use,
as the room was dark, and I could not see my field of view
until the spectrum of the prism was directed into it. The
light afforded by the prism was too faint for the power I used
with the solar light. I was therefore obliged to reduce it one-
half. Even then the blue ray had not sufficient power; the yel-
low one had, and seemed little different in its effect from. the
taper itself in the same state of intensity. Suffice it to say,
that I got the same results as before,—that is, when I obtained
the light of the prism perfectly direct I obtained achromatism ;
when it came obliquely, the coloured fringes instantly appear-
ed, modified by the tint of the ray, and much in the same
way as if I had looked through a coloured eye-glass at the
image produced by common light. Wishing to sift this phe-
nomenon to the bottom, I then used the light of the taper in
its natural state, and found that there is one particular po-
sition in which it may be placed behind the stage, so as to
give apparent achromatism with any sort of microscope
whatever, however chromatic it may be. 'This appears to be
as nearly as possible in the axis of the microscope; if it is
placed ever so little out of it, the coloured fringes instantly
show themselves. I am confident that I could make an un-
experienced person believe in the achromatism of any micro-
scope whatever by making this arrangement ;* and a most

* Upon a careful re-examination, I do not think myself justified in say-
ing that achromatism can really be so produced ; it should rather be termed

56. Dr Goring on Monochyomatic Light, &c.

fruitful source of deception it must Prgveras to the achromas
tism of these instruments ! | :

It is nowonder tbat we should havesomany kinds of snondeliges
matic lamps and light, when a common candle will answer just
as well. As prisms and lenses have a great analogy to each other
in their operation, J thenexperimented onthedispersed solar light
with them, and it always appeared to me that when I could suc-
ceed in getting the light from the diaphragm thrown perfectly
direct through a prism, no sensible secondary dispersion was
produced ; but when it came obliquely, the aperture was com-
pletely fringed by prismatic tints in their natural order. As
it seemed to me that a piece of rubbed glass placed over the
diaphragm caused the light to be equally diffused over the
interior of the tube, whether it came obliquely or not, I tried
the effect of the prism upon it, but the light always seemed to
be dispersed in this way as before. (For these experiments I used
the apparatus first described, only I took out the object-glass
and eye-glasses of the microscope, and looked at the diaphragm
through a small prism held in my hands at the ocular end of
the body.) In order to have made these latter experiments
properly, I should have required a heliostat moved by clock-
work, for the motion of the earth subverted the direction of
the solar beam. Immediately I had got it truly in the axis of
the body of the microscope; and the power I possessed of
counteracting this was only by means of adapting the prism
to the motion of the light with my hands.* I should have
liked to have dispersed the colour a second time, and fairly
produced a spectrum of it on paper under the circumstances
a great reduction of dispersion, the effect of which is assisted by the fog
occasioned by spherical aberration, as well as by the confusion produced
by solar light, when I used it as before stated. If there really is achroma-
tism, it is confined to a small portion of the centre of the field of view, and
even there to a point, which seems to depend much upon the position of
the eye; however, I have no doubt that it would be considered such by

those whose eyes have not been sharpened by habits of koking into the
defects of optical instruments.

* When the light came quite direct, I of course caught the image of
the sun, which dazzled my eyes too much to permit me to be quite cer-
tain of the tints or colour I saw. It is very possible that here again there
might be only a great reduction of dispersion as in former instances.

a |

Dr Goring on Monochromatic Light, &c. = 57.

-

of direct and oblique incidence. I hope some person, better
able than myself to look into these things, and better furnish-
ed with apparatus, will examine this subject in a proper man-
ner. The impression produced in my mind was, that a cer-
tain quantity of white light enters into the constitution of each
of the seven coloured rays, as water does into the constitution
of alcohol, and may be rendered manifest by the dispersive
power of prisms and lenses under the circumstances I have de-
scribed.

At all events, J think no effective monochromatic light is
likely to be obtained for illuminating chromatic microscopes,
so to render them equivalent in their action to achromatic
ones.

I shall now proceed to notice some assumptions respecting
the achromatism of erecting eye-pieces and engyscopes, which
consist in supposing that, by arranging a system of glasses
with certain intervals, we may form an achromatic combina-
tion without correcting what I shali call the objective part sepa-
rately. Had these proceeded from more obscure and less in-
fluential persons, I should have allowed them to rest in peace ;
but the power of proficients in the exact sciences is so great,
either in retarding or advancing the perfection of optical in-
struments, that I feel it absolutely necessary for my own ‘\ho-
nour, and that of the improvements lately introduced into use,
to endeavour to rectify what seems to me retrogradations and
abuses. The dicta of mathematicians of high reputation are
generally received without examination, because it is conceiv-
ed, aud not without justice, that they can hardly say or do
any thing wrong. If they could, many there are who will
think it more creditable to be in the wrong with them than in
the right with mere practical men. Yet optics is both an ex-
perimental and a demonstrative science; and though experi-
ment ought certainly never to dictate to analysis, (which
would be placing the cart before the horse with a vengeance, )
yet the testimony of those organs which are to use optical in-
struments must not be wholly rejected.

A telescope and what is usually termed a compound micro-
scope pass into each other by insensible degrees, so that it is
somewhat difficult to define the one distinctly from the other,

58 Dr Goring on Monochgomatic Light, &c.

otherwise than by drawing a line of demarcation between them,

by reference to the length of the anterior and posterior conju-
gate focus of the object-glass. Thus we may say that a telescope

has its anterior conjugate focus, or the distance of the object

from the object-glass longer than the posterior, or that next
the eye-piece. Inan engyscope the case is reversed.* 'The line
of separation is therefore where the two foci are equal ; such
being the case, we may make an object-glass of short focus,
say four inches, gradually pass through all the gradations from

a telescope to a compound microscope, without making the

least change in the principle on which the image is formed.
Now, no optician has ever yet dreamed of making an achro-
matic telescope by arranging a system of glasses at particular
intervals, though, if a compound achromatic microscope or
engyscope can be so made, we ought surely to be able to con-
struct a telescope of some sort or other on the same principle,
the two instruments, as before stated, being so similar im
their action of forming an image. It is a consideration also
worthy of being attended to, that the first practical opticians
in Europe have now all adopted the method of making achro-
matic engyscopes precisely on the principle of telescopes,—
that is, by correcting the objective part by means of concaves
of flint-glass. Such men as Fraunhofer, Utzneider, Amici,
Selligue, Chevalier, Dollond, Tulley, would scarcely have all
adopted so difficult a task as that of making these minute ach-
romatic glasses, if it had been possible to obtain a perfect cor-
' rection of chromatic and spherical aberration without them.
They are all-in the habit of making so called achromatic,
erecting eye-pieces for spy-glasses, (which are in fact nothing
but compound microscopes;) and it is hardly credible, that
they should not have perceived the application of them as such,
. if they were, bona fide, achromatic. But the fact is, these ar-
tists all know the fallacy of these things, and how, and under

* Perhaps a definition of an engyscope, as distinct from a telescope, may
be given thus :—It is a telescope made on a very small scale, having its ob-
ject-glass and the conjugate foci thereof reversed. It may not be generally
__ known that an engyscope will act with a concave eye-glass, just asa Gali-

lean telescope does, and that its focus can be adjusted by moving the q7ee
glass alone, instead of the whole body, as is usually Pees

+ 4
- 4

Dr Goring on Monochromatic Light, &e. 59

what circumstances, they are achromatic. I propose to show
that an engyscope cannot be made achromatic in any other
manner than as a telescope is, and that the new achromatics
‘are consequently not superfluous.

The angle of aperture of the erecting eye-pieces of spy-glasses
is usually very small, not exceeding five or six degrees; the
‘chromatic aberration, therefore, of their objective part, is hear-
‘ly insensible to vulgar eyes. Moreover, it is well known that
all working opticians are in the habit of over-correcting the
colour in the object. glasses of those telescopes which are ex-
pressly made for viewing terrestrial objects. It is supposed by
some that the predominance of the blue and purple rays, which
is occasioned by this over-correction, tends to exhibit terrestrial
‘objects better than they would be seen if the instruments were
perfectly achromatic,—an absurdity which 1: shall not take
the trouble of refuting.

The real manner in which a beneficial operation is produced
by this over-correction for colour, is by its effect on the eye-
piece, which it greatly ameliorates and improves, by neutra-
lizing the red and orange light, which would otherwise greatly
preponderate in it, so that the totality of the instrument may
be considered sufficiently achromatic for practical purposes ;
nevertheless, under certain circumstances, the uncorrected co-
lour of the eye-piece renders itself very manifest ; as, for ex-
ample, when we view some dark object, such as the rigging of
a vessel or a weathercock, against the light of a clear sky. For
by placing the object at the edge of the field of view, while we
look obliquely at it from the opposite side, so as to catch an
eccentrical pencil, the uncorrected colour is instantly felt.

Now, as I am contending for the principle of achromatism,
I shall proceed to show, that all erecting eye-pieces of the or-
dinary construction, though they may, Wate certain circum-
stances, and in a practical point of view, pass for achromatic,
yet have in good earnest no achromaticity about them; and
of this I think any man may convince himself by the follow-
ing experiment :—There is a small circular disk of brass with
a hole in it, placed between the two bottom glasses of all erect-
‘ing eye-pieces, which, when the telescope is in action, serves

only to exclude the. false light which is reflected by the long

60 Dr Goring on Monochgomatic Light, &.

tube. The aperture of the hole in it is usually about one-
tenth of an inch in diameter, or just what will allow the pencil
of light from the object-glass to clear it. The telescope will
be just as achromatic without it as with it, when the eye-piece
is removed from the telescope and tried by itself. _

As a compound microscope, the said diaphragm acts a very
important part, and in fact reduces the angle of aperture of
the eye-piece nearly to that of the object-glass of the telescope
along with which it acted, being, as I said before, perhaps six
degrees. Now it is no wonder that with so small an opening,
(though unassisted by the over-corrected object-glass,) the eye-
piece fixed should still pass for achromatic with those who know
not how to look into its defects,—just as we see mulattoes and
people of colour who have not much black blood in their veins
pass for whites. Let, however, this said stop be knocked out,
or, what will amount to the same thing, let it be opened out
with a broach, wnéil it will admit the whole of the pencil of a
verfectly achromatic object-glass having a large angular aper-
ture ; for example, one belonging to an opera-glass, or a per-
spective, or some of those dumpy achromatics which Ramsden
was in the habit of making, this will probably cause an en-
largement of the perforation of the said stop from ,/; to % of an
inch, if the focus of the first glass is two inches. The ra-
tio between the diameter of the visual pencil, and that of the
object-glass will truly represent the magnifying power of the te-
lescope, and it may be known to have attained its due aperture
when none of that of the object-glass is cut by it. On trying
any telescope thus mounted, it will soon be seen whether the
eye-piece is achromatic or not. Or it may be tried as a com-
pound microscope by itself, and I can only say that a man who
will not be able to perceive colour in it, must be either utterly
blinded by preconceived opinions, or by a complete incapacity
to discuss the merits of optical instruments. Nevertheless,.
there is a construction for an erecting eye-piece which is bond
Jide achromatic to any angle of aperture as it appears to me,
namely, a simple reduplication of the Huygenian eye-piece,
that is using one to erect and form the secondary image, and
another to view it, which will give a compensation to each
part; but this construction is never employed,—at least I never

Dr Goring on Monochromatic Light, &c. 61

met with it, because, I presume,if we use a Huygenian eye-piece_
to form a secondary image, the component lenses will be nearly
of the worst figure, and in the worst position, for giving dis-
tinctness, which is a quality to be preferred even to achroma-
tism. I need not observe that such a construction could never
be used by itself as an engyscope or compound microscope,
because its focus being negative, or between the glasses, it can
only be made to operate on an image already formed.*

In the year 1815, being then a student in the University of

‘Edinburgh, I began my career as a reformer of microscopes,
from reading the article Telescope in the Encyclopedia Britan-
nica, (written by Professor Robison,) and chiefly from the
consideration of a passage in it, which I shall here quote.

“* We have examined trigonometrically the progress of a
red and a violet ray through many eye-pieces of Dollond’s and
Ramsden’s best telescopes ; and we have found in all of them
that the colours are united on or very near the field-glass; so
that we presume that a theory somewhat analogous to ours
has directed the ingenious inventors. We meet with many
made by other artists, and even some of theirs, where a consi-
derable degree of colour remains, sometimes in the natural or-
der, and often in the contrary order. This must happen in
the hands of mere imitators, ignorant of principle. We pre-
sume that we have now made this principle sufficiently plain.
Fig. 20, No. 2, represents the eye-piece of a very fine spy-glass
by Mr Ramsden ; the focal length of its object-glass is 8} in-
ches, with 1,;th of aperture, 2° 05’ of visible field, and 15,4
magnifying power. The distances and focal lengths are of
their proper dimensions, but the apertures are a-half larger,
that the progress of « lateral pencil might be more distinctly
drawn. The dimensions are as follow :—

Foc. lengths Aa = 0,775 Bb = 1,025 Ce = 1,01 Dd = 0,79.

Distances AB=1,18 BC=1,83 CD —1,105.

“< It is perfectly achromatic, and the colours are united, not

* Such an eye-piece is very foggy when acting with a large opening, though
it must be confessed that the focuses and the position of lenses become
of little consequence in a practical point of view, if their acting aperture is

exceedingly small, for the eye cannot, under such circumstances, appreciate
their effect.

62 Dr Goring on Monochromatic Light, &c.

precisely, at the lens Cg, but.about 5th of an inch nearer the
eye-glass.
- Tt is obvious that this combination of glasses may be tise

asa microscope; for if, instead of the image formed by the

object-glass at FG, we substitute a small object, illuminated:
from behind, as in compound microscopes; and if we draw
the eye-piece a very small way from this object, the pencils of
parallel rays emergent from the eye-glass D, will become con-,
vergent to very distant points, and will there form. an in-
verted and enlarged picture of the object, which may be viewed
| by a Huygenian eye-piece; and we may thus get high magni-
fying powers without using very deep glasses. We tried the
eye-piece, of which we have given the dimensions, in this way,
and found that it might be made to magnify 180 times. with
very great distinctness. When used as the magnifier of a so-
lar microscope, it infinitely surpasses every thing we have ever

‘seen. The picture formed by a solar microscope is generally

so indistinct, that it is fit only for amusing ladies; but. with
this magnifier it seemed perfectly sharp. We therefore recom-
mend this to the artists as a valuable article of their trade,”

I caused that distinguished artist, Mr Adie, of Edinburgh,
to execute’ for me a microscope similar to that recommended

by the Professor, on which no expence was spared; it of .

course gave an erect image. I was not content with it, its
construction being too complicated, and its length inconve-
nient ; moreover, though its angle of aperture was no greater
than that usually given to eye-pieces, its chromatic aberration
forced itself occasionally on my unwilling conviction in a man-
ner which I could not resist in spite of my faith in analysis.
I naturally, therefore, imputed this defect to Mr Adie’s im-
perfect execution, and set him to work afresh to make another
microscope on the plan of an erecting eye-piece of the ordi-
nary construction, gaining the different powers by the appli-

cation of Huygenian eye-pieces to the image formed by the —

two bottom glasses. I was very much pleased by the distinet-
ness of this microscope, and so were all who examined it. Still,

however, #¢ was not achromatic, so I set Mr Adie down, at the
time, for a bungler who could not adjust the foci and intervals
of the glasses in a proper manner ; and determined to have

of

SS ee

Dr Goring on Monochromatic Light, &c. 63

the thing done effectually, if possible, by London artists, which.
resolution I executed afterwards. In the course of these expe-
riments I found the utility of getting the power at the objec-
tive, instead of the ocular, end of the instrument, as a much
sharper image was thereby obtained. I accordingly deepened,
what I shall call the object-glasses, as far as one-fourth of an
inch focus, and obtained a very superior microscope; an account
of which has already been laid before the public.

. As to achromatism, however, I regret to state that the Lon-
don workmen succeededno better than Mr Adie, though I am not
quite certain if a feeble compensation was not produced some-
times, when the curves of the two plano-convex lenses, which
composed the object-glass, were turned towards each other in
the manner they have been engraved.. I moreover once
thought that I had got a combination that was achromatic, at
least upon opaque objects; and being determined to leave no-
thing to be done by any man who should take up the subject
after me, I resolved to apply to Mr Tulley of Islington, to
have his opinion and advice on the subject.. He soon convin-
ced me of the impossibility of obtaining achromatism in any
case where an image was to be formed from a real object,
otherwise than by the action of concaves of flint-glass, and
that my ignorance of the art of seeing the flaws and imperfec-
tions of optical instruments was the sole cause of my suppos-
ing I had ever obtained even an approximation to achroma-
tism.

Now, as my respect for truly exact science is not surpassed
by that of any man, I must confess that all these circumstances
created in my mind some doubts and misgivings as to the ac-
curacy of Professor Robison’s statements and theories, not very
much unlike what I have observed in farmers in the country,
when unable to reconcile the actual state of the weather with
the predictions of Moore’s Almanack, in which their faith is
altogether inflexible.

These theories of Professor Robison seem to have been re-
suscitated by Professor Airy and Mr Coddington. The work
of the latter gentleman on the refraction and reflection of light,
contains the substance of Professor Airy’s papers on these sub-
jects; and whether it is considered as a work of originality, or

64 Dr Goring on Monochromatic Light, Sc.

as a compilation from the writings of our first opticians, it is

admitted to be the best publication of the kind at present ex-
tant, and wants no feeble testimony of mine in its favour.

I presume that the most staunch advocate for the dignity
of exact science, while he will insist on the vast superiority of
its evidence over that afforded by the senses, will never con-
tend that it is to run diametrically opposite to their testimony.

I shall venture, though well aware of what I am doing, to

impugn its infallibility in the case of these theories of achroma-
tism of Professor Robison, Professor Airy, and Mr Codding-

ton, on the ground that no artist is able to make an achromatic

instrument according to them. * |
All that it is in my power to do will be to oppose theories,
by what we call, in common language, facts; for I must state

that, when I view the subject theoretically, I am utterly unable

to detect the least flaw in the aforesaid theory. It seems im-

possible to deny that instruments constructed according to
them ought at least to be achromatic. It is not to be expected,

indeed, that a poor sciolist like myself should be able to school

men of such highly mathematical acquirements as the afore- .

said savans : the task must evidently be left to mathematicians
whose calibre is still larger than theirs. I have already par-

tially expressed my own views concerning achromatism, and I’

shall endeavour now to expand them into the following proposi-

tions, which rest only on the basis of the evidence of the

eyes or experience.
1. When achromatism is obtained by the adjustment of len.

ses to particular intervals, as in the case of the Huygenianeye-

* We surely have a right to form a certain estimate of the soundness of
a theory by its fruits. I once had the honour of looking through-a tele-

scope of the Gregorian form, but constructed with mirrors of glass by Mr

‘Tulley, according to the theory of Professor Airy. Mr T. had expended

the whole of his skill upon the instrument, and had worked the said mirrors:

over and over again a great number of times till his patience was exhaust~

ed, yet the confusion in the vision produced was so great, that it was but just -

possible to recognize objects. I think when such an artist as Mr T. can-
not bring a telescope something near to distinct vision, when working to
the utmost of his ability by the-theory laid down for him, there must be
something wrong about it.

ra
—————————— ee ee

Dr Goring on Monochromatic Light, Se. 65

piece such achromatism is absolute and perfect, and not like that
"effected by the combination of a concave lens of flint-glass with
‘a convex of plate or crown-glass, which never effects a com-
plete neutralization of the chromatic aberration, as is well
known. Therefore, if engyscopes and telescopes could be made
by the adjustment of a system of lenses to particular intervals,
their achromatism ought to be decidedly superior to that ob-
tained by the action of concaves of flint-glass, and equal to_
that of a reflecting instrument. 3 i

2. The only kind of achromatisation produced by convex
lenses which is known in practice, is when two are adjusted to
an interval equal to one-half the sum of their focal distances,
or thereabouts. (These conditions are not rigorously neces-
sary, as the lenses may be placed somewhat nearer than that.)
Moreover, the intervals seem to differ a little according’ as the
eye-piece is adapted to an engyscope or to a telescope,—at least
-if the power of the former is low and the tube short..

3. Many modifications of this combination may be made, as
by doubling or tripling what are usually termed the eye and
field-glasses, so that the compensation for a double or triple
eye-glass may be thrown upon a double or triple field-glass,
and that there may or may not be an’ interval between the
lenses composing the eye’and field:glasses ; still; however, the
mode of operation is the same.

4. In order to form a truly achromatic erecting eye-piece
or engyscope, there must be a compensation both in that part
which erects and forms the image, and in that which views it ;
therefore no achromatic erecting eye-piece or engyscope can
be made with so few as three lenses, because either the objec-
tive or ocular part must inevitably be without compensation.

5. An erecting eye-piece can only be made really achroma-
tic, (if we'do not employ concaves of flint-glass,) by combin-
ing two Huygenian eye-pieces, or some modification thereof,
together, in such a way that one shall erect and form the image,
while the other is made to viewit. As to the interval between
them, or what may be termed the second and third glasses, if
the eye-piece consists of four, it may be greatly varied without
sensibly affecting the achromatism.

6. Such an eye-piece could only be used for viewing an
image, and could never be employed as an engyscope, because

NEW SERIES, VOL. v. NO 1. JuLY 1831. E.

66 Dr Goring on Monochyomatic Light, &c.

it would have no external focus in front of the bottom glass;

therefore, an achromatic engyscope can only have a double
compensation in the same way as a telescope has it, of which

latter instrument it is nearly a modification; and as it is ex-
ceedingly difficult to procure perfect flint-glass lenses of large
diameters for the object-glasses of telescopes, it is devoutly to
be wished, that, by the omnipotence of analysis, we may at
length be enabled to construct them absolutely achromatic, of
one kind of glass only, by adjusting a system of lenses to par-
ticular intervals ; while, with proper attention to the forms of
the lenses, their spherical aberration ought at least to be re-
duced to insensible quantities, (using only a small angle of
aperture,) though it could not perhaps be wholly removed.

Now, on comparing these propositions with those contained |
in Mr Coddington’s work, under the head of “ achromatism,”
page 262 to 269, it will be seen how completely I have been
compelled to leave him on the left hand. It will be a memo-
rable instance of the fallibility of analysis, and perhaps the first
on record if the said theories are found to be at fault. I shall —
leave it to others, however, to draw conclusions and weigh pro-
babilities against each other. I have always myself found that
good sound theories will produce instruments which satisfy the
eye; and though it must be admitted that this organ is exceed-
ingly coarse and easily pleased in the generality of mankind, it is
nevertheless in many instances capable of acquiring a refined
and accurate taste in optical instruments by a good education, —
just as it does in pictures and other works of art. In the second
volume of Mr Hume’s essays, section 12, entitled, * of the
academical or sceptical philosophy,” part second, there are some
curious reasonings on the subject of mathematical demonstra-
_ tion, which the reader would do well to consult.

I may observe, that Mr Coddington has been at the pains of
falsifying his own theories, practically at least, to the best of
his abilities, by presenting to opticians a compound micro-
scope, termed achromatic, which is constructed according to
them. It is described in his treatise on the “ Hye and Optical
Instruments,” pages 60 and 61, under the head of Acuroma-
tic OssEct-cLass, and is represented in plate 13, figure 190.
He has implicated articles 205 and 210 with the expressions
in pages 261 and 268, in the treatise on the “ Refraction and

~~

Dr Goring on Monochromatic Light, &c. 67

Reflexion of Light,” in the construction of this instrument ;
and if he had succeeded in making it achromatic, there would
be good reason for asserting that it is unnecessary to correct

' the dispersion of its object-glass separately, as well as *¢ that the

intellectual and manual labour, which has of late years been
expended on the construction of achromatic object-glasses, has
not only been unprofitably directed,” but in a manner wholly
thrown away, since, if his theories were accurate, a much bet-
ter and purer achromatism ought to be obtained by the simple
adjustment of a system of lenses to proper intervals, I assert
point blank, that his instrument is as complete a failure as any
thing of the sort I ever attempted myself. I have examined
one of these instruments of the latest and most improved con-
struction, made by Mr Carey, (which, however, differed not
materially from that described in the treatise on Optical In-
struments, except in having a double field-glass,)* and can, I
think, be positive that both the chromatic and spherical aber-
ration of the objective part was wholly untouched, and that the
eye-piece, consisting of four glasses, was achromatic. Nothing
can surpass the beauty of the field of this microscope ; but if I
may be allowed the expression, notwithstanding its extent and
flatness, nothing more can be made to grow in it than in that
of any ordinary compound microscope having a well figured
object-glass of the same power, and angular aperture, used
with an Huygenian eye-piece, also of equal power with that
applied to the instrument in question.

The dispersive and spherical error of small lenses is un-
doubtedly small, as I have frequently remarked ; but it is not
insensible even with a very small aperture to those who know
how and where to look for it. Some persons use it at the first
glance, others only if it is pointed out to them, and some not
at all, if it happens to contradict their theories and precon-
ceived opinions ; for there is no blindness greater than that ge-
nerated, not in the organ of sight itself, but in the mind which re-
ceives its impressions. We are indeed so accustomed to tolerate
aberration in microscopes that it frequently is unable to sti-
mulate our senses. I shall here instruct my reader, if I can,

* This was similar to that described in No 5, Art. xvii, p. 155 of this
Journal.

68 Dr Goring on Monochromatic Light, &c.

in the way of examining the dispersion of a lens; it is as fol-
lows :—Place a small globule of quicksilver on a perfectly
black ground of some kind or other without polish ; let it be
placed on the stage of a microscope, which must be resented
towards a window in such a manner that the uncondensed
light thereof shall fall freely upon the globule, for the light of
a candle may be employed for the same purpose ;* but it must
not be condensed by a lens, or mirror, or silver cap, of which
latter the globule would form an image. The object is to allow
the globule to form a minute picture, either of the candle or
of the window, by its own natural action. All we have to do
is then to bring it into the focus of the object-glass or lens,
whose dispersion we wish to examine, and to observe the phe-
nomena presented by it, both in and out of focus. If it has dis-
persion, the different prismatic colours will appear according to
the order of their refrangibility. I shall give a sample of those
visible with a globular object-glass, of half an inch focus, and
2-10ths of an.inch of aperture, (being what would be com-
monly used for a working instrument,) employed with a_per-
fectly achromatic eye-piece, and the light of a window.

In focus there is a.centrical image of the window, which is
surrounded by a disc or halo of green, which is again sur-
rounded by a circle of indigo, the whole being contained with-
ina border of purple. ,

Within the focus are found the following colours : in the

* The light of the sun may also be employed, which, when allowed to
fall freely on the globule, gives a miniature image of the sun, forming ~
a true artificial star, (the queen of test-objects to the initiated optician,)
as the light it affords is more intense than any other, so it exhibits disper-
sion in the most vivid and brilliant manner._

+ This object-glass was made by Mr W. Tulley, who presented it to
me several years before Mr Coddington had introduced the subject to the
notice of the public. {It was made by Mr T. in order to procure a pencil of
light in the same state from every part of the object, and to render the field ©
of view alike in every part which it no doubt effects. As, however, its
aberration is very violent, so as to require a strong concave to correct it, .
which, when applied, utterly subyerts the equalization of its various pencils,
it has no advantage over an equiconvex lens ;\he therefore abandoned it.
I believe he will not, therefore, be very jealous about the honour of pater-
nity in this matter. A good thing has generally half a dozen fathers to it,
and in.as many different countries a bad thing only one,

¢

: ,

Dr Goring on Monochromatic Light, &c. 69

centre of the globule is a round spot of purple surrounded
by.a halo of blue, a second of green, a third of yellow, a fourth
of orange, and a fifth of red.

Without or beyond the focus, a dise of faint greenish yel-
low, surrounded by a halo of strong green, without which is a
halo of blue, and lastly, one of purple.

Moreover, when an instrument is perfectly achromatic, there
is a total absence of all minute fringes of colour. When. it is
used on transparent objects with oblique candle-light, nothing,-
in short, but'the natural colour of the object can be made to
appear under any circumstances whatever ; for the secondary
spectrum is too faint to be seen, unless perhaps 1 in object-glasses |
of at least an inch aperture. If I had employed for these expe-
riments an object-glass of an inch focus, and 4-10ths of an inch
aperture, the colours enumerated would have been much more
intense and striking ; and if one only of 1-8th of an inch focus,
and an equal angle of. aperture, far fainter, being nearly in the
ratio of the quantity of light dispersed by the object-glass.

A curious effect is produced. by using an object-glass with
a very large angular aperture ; for example, by employing the ©
naked opening of the aforesaid globule, which is half an inch, so
strong a fog is occasioned by its spherical aberration, as to
drown and confuse the chromatic, so that it appears in a great
measure obliterated, or very much reduced in quantity, (though
there is no doubt that it must be increased.) Chromatic aber-
ration is never so sensible as when uncombined with spherical, as
in Mr Herschel’s compound aplanatic lens of one kind of glass,
which, having no spherical aberration with a very considerable
aperture, is so clear as to allow the chromatic to be seen in
the highest perfecuon.*

Now it is scarcely necessary for me to ask, whether it is
right or not to correct the dispersion I have pointed out ; but .
how is it to be done by an achromatic eye-piece ? If a man
chooses to tell me that those little rainbows and fringes of co-
lour, which appear in objects viewed by achromatic instru-

* Though the dispersion of a diamond or sapphire lens, especially the
latter, is much less than that of glass, lenses formed of: these gems al-
ways seem to me to colour more than glass, which is accounted for by their
greater distinctness,

70 Dr Goring on Monochromatic Light, &c.

ments, are, in his opinion, highly ornamental, and not at all
injurious to vision, I can only say I wish him:a better taste. I
have seen people in the streets paying their pence very cheerfully
to a peripatetic astronomer for the sight of a beautiful rainbow
about the moon, which he had discovered with the curious |
telescope he was exhibiting, and which I had certainly the
honour of seeing myself, together with the beautifully prisma-
tic tails of some aquatic insects shown by a microscope con-
structed on the same principle as the telescope. If people like

to eat dirt they shall meet with no opposition from me,—much
good may it do them.

I have certainly myself seen a thirty inch telescope of two
inches and a half aperture in which there was an immense quan-
tity of uncorrected colour, nevertheless able to show the star
epsilon Bootis very well, and other things in proportion, ow-
ing to its spherical aberration being very exactly corrected.

The only case, I think, in which colour can be said to be cor-
rected by an eye-piece, is when an object-glass over-corrected
for colour is made to act with a chromatic eye-piece, as I have ~
indeed before stated, having once caused the object-glass of an
engyscope to be over-corrected, because it was to act with an
erecting eye-piece of the ordinary construction. The beneficial
effect of this arrangement was very sensible, and it might either
be said that the eye-piece corrected the object-glass, or the ob-
ject-glass the eye-piece. I am of opinion that the chromatic

aberration of simple microscopes and doublets is not sufficient

to produce any. sensible detriment to vision, unless with exceed-
ingly minute and delicate objects, beyond that of giving a false
colouring, especially if oblique light is used. This, however, we
soon learn to allow for ; it is moreover considerably concealed
by their spherical aberrations.

As to the spherical aberration of obyjecteylanees ind metals, —
- inasmuch as it is sensible to vision, I am persuaded from: re-
iterated experiments, that the power which an eye-piece pos-
sesses of modifying or altering it is exceedingly feeble. A case,
however, in which I can be positive that it does actually correct
it, is in that of the Gregorian telescope, in which, if the large
metal is nearly right in point of figure, for example, a little too
much inclined to be spherical or parabolical, the error may be

- Dr Goring on Monochromatic Light, Sc. 71

corrected by giving the small one an hyperbolical figure. More-
over, in the Cassagrainian telescope, it is well known that the
aberration of the two metals (supposing them to be both spherical)
is equal to the difference between the aberration of the convex
and the concave, which is a clear proof that an eye-piece may
correct to a certain extent ; (for I consider that the small metals
and eye-glasses of the Gregorian and Cassagranian telescopes,
in their combined action, are neither more nor less than eye-
pieces, which operate by forming a secondary image like the
erecting ones of common spy-glasses.) I should, moreover,
conceive that the same conditions would occur if achromatic
glasses of similar force, and in equivalent states of correction,
were substituted for the metals of the Gregorian telescope,
and made to operate against each other on the same principle; .

but this experiment I have never tried, either in telescopes or

engyscopes.

I have in vain endeavoured to find .an inverting eye-piece
which would exert an influence over the state of spherical
aberration of the object-glasses and metals of engyscopes. My
way of judging was to form an image of an/artificial star by
their unassisted operation, as magnifiers in a solar opaque mi-
croscope, making the posterior conjugate focus to be of the
same length as in an engyscope, that is, eight or nine inches,
and having carefully examined the state of aberration in the
picture, I then have attempted to modify it (when formed at
the field bar of an engyscope) by various eye-glasses ; but so
far as my eyes are capable of affording a criterion, I never
succeeded in any degree. The image appeared as intractable as
a picture formed by human hands, and remained inflexible
both in its defects and excellencies, whatever they might be.
The various eye-pieces I employed gave a better or worse field
of view, were or were not achromatic, &c. as regarded their
own intrinsic operation ; for example, they might give the ob-
lique pencil in a better or worse state; but if the said oblique
pencil came in a confused or distorted state from the object-
glass, I never could make them improve it. At the same time,

_ I think it proper to observe, that I never tried thoroughly the

effect of positive achromatic eye-pieces in which there was a
correcting concave lens of flint-glass.

(2 Dr Goring on Monochgomatic Light, §c.

I shall now give the construction of an erecting’ eve-piece i
or engyscope, whee is both, achromatic and aplanatic to an _—

aperture of about 27°, and having, moreover, a reasonable
good correction of the oblique pencil. It is represented by Fig.

1. Plate I. a and b aré two achromatic lenses; the focus of

b is to that of a as two to one, andthe interval between them
is also equal to one ; ¢ is a stop placed immediately behind 6,

to regulate the aperture; a may be over-corrected for spheri-~

city and dispersion ; 6 under-corrected * for both, in such a

manner that their aberrations shall neutralize each other, or.

each lens may be perfect in itself; de is an Huygenian eye-
piece. The interval 6 d must be regulated according to cir-
cumstances; but may be roughly stated as equal to that be-

tween the second and third glasses of a common erecting eye-

piece of the same power. +

I have already stated that I consider the ordinary erecting
eye-plece sufficiently perfect for practical purposes; but I think
it would be a great improvement on spy-glasses if they could
be shortened tiearly one-half, so that they should: be easily
held and directed by the hand, when charged with a power of
thirty or forty. I think an aperture of two inches and a half
or three inches does as much upon terrestrial objects, at least
im the day-time, as any other, the focal lengths of which are
generally not less’ than thirty inches, which render the’ glass
too long to be used without a stand. If the focal length was

reduced to fifteen inches, the angular aperture would thereby _

be doubled, and with it the defining power also, (provided it
could be perfectly executed.) In this case the erecting eye-piece

I have given would be indispensable, for the colour of an or-
dinary one would become very sensible. Moreover, when we _

apply an erecting eye-piece to the object-glass of an engyscope,
so as to obtain a low power, and for that end thrust it far in-.

* Mr Lister has ascertained that an achromatic glass, having its inner
surfaces in contact will vary in its spherical aberration according to cir-
cumstances. It matters not how or in what manner, or upon what baat i
ple, the aberrations of the two lenses are balanced.

+ When this construction is used as an engyscope, there will be an
abandant space left in front of the glass a for the illumination of opaque
objects, provided its focus is not shorter than ,4,ths of an n inch.

6

Dr Goring on Monochromatic Light, &c. 13

to the body, so as to approach very near to the object-glass,
(in which case what I shall call its posterior angle of aperture
becomes considerable,) a truly achromatic construction is also
highly requisite. ‘ |

Fig. 2 represents a positive inverting eye-piece for astrono-
mical telescopes or for engyscopes used with micrometers ; it
is perfectly achromatic, and consists of two glasses, a and 0,
with a certain interval between them, for the purpose of, im-
proving the oblique pencil. They maybe either achromatic and
aplanatic in themselves or by mutual correction. * I am’sorry
to say that I have not been able’ to procure any combination
which gives so flat a field of view as I could wish consistent

with perfect distinctness. If it is thought worth while to ob-
tain a large field at the expence of centrical perspicuity, we
have only to reverse the position of the glasses, and that: pur-
pose will be accomplished.

I may observe, that if in these constructions the achromatic
glasses have their inner surfaces in contact, and are cemented
together, there will be no sensible loss of light beyond that
occasioned by two common lenses. |

I must now say somewhat about-oblique pencils. They are
very much mistaken who suppose that they have not received
quite as much consideration as they deserve from those who
have interested themselves of late in the improvement of the
microscope. It is well known to every man practically acquaint-
ed with optics, and ought to be much better by those who know
the science theoretically, that in all constructions whatsoever
there is a perpetual system of gaining advantages in one di-
rection and losing them in another, just as in mechanics, —what
is gained in power is lost in time, &c. It is not permitted: to
man, assisted by the most powerful analysis, to combine to-
gether every advantage he may desire. He must content him-
self with what is attainable. According to the laws of the re-
fraction and reflexion of light, I have ever found that all those
constructions which give a very large angle of aperture com-
bined with great distinctness, invariably produce what is called

* Their foci may be varied at pleasure, provided that the second or field-
glass is not less than that of the first.

74 Dr Goring on Monochromatic Light, Sc.

a bad field of view, that is to say, the vision is only perfect in
the centre. In refracting instruments, a good deal may be
done by combining several object-glasses together, more espe-
cially if they have intervals between them, (which, however,
produce great inconvenience, by shortening the anterior con-
jugate focus, and thus precluding the use of high powers.)
As the action of metals is very simple in comparison to that
of lenses, I shall give an illustration of the mischief occasion-—
ed by what is called improving the oblique pencil in the Ami- —
cian reflecting microscope. It must be evident, that, as the an-
gular aperture is increased, the error of the oblique pencil |
must also be augmented ; for it will come more and more ob-
lique. Now it.has actually been recommended to opticians to
render the metals of the aforesaid instrument spherical, be-
cause in this case every pencil becomes equalized, and may
be said to be equally bad or good, distinct or indistinct,
throughout the whole field of view, though, so far as the ob-
jective part of the instrument is concerned, the whole instru-
ment becomes utterly worthless if this figure is adopted.
Those who work the metals of this instrument well know what
infinite pains they have to get rid. of this spherical figure and
to attain the true one, * and that when they have done so, the
point is effected at the expence of a certain want of perspicuity
about the edges of the field of view, which is altogether wre-
mediable with low powers, which take in a large portion of the
marginal part of the image. If Gregorian and other telescopes,
having a large angular aperture, are charged with a low power,
the same defect is also very perceptible in them.
Of a piece with the performance of a spherical metal is that
of a globular or bird’s-eye object-glass, which is considered. to
produce an excellent correction of the oblique pencils, be-
cause they come ewactly like the centrical ones, which are ut-
terly uncorrected.
When the omnipotence of analysis shall point out some

* IT have known Mr Cuthbert to have been employed a whole wack | in
getting rid of nothing but the spherical error of one of his metals of °,ths
of an inch focus and the same aperture, and not able to succeed at ‘all j in
certain states of the weather, supposing always that a perfect figure was
to be combined with a perfect polish.

/

Mr Potter on the specific heats of Metals, &c. 15

truly achromatic and aplanatic construction which will give
an oblique pencil as perfect as a centrical one, then will the
labours of mathematicians have assumed a proper direction.
At present I am afraid they have been hollowing before they
are out of the wood. I trust, however, that the time will
come when the subject will be taken up in the right point of
view, or it will be likely to remain a standing opprobrium ma-
thematicorum.

What could be a more beautiful and original subject for
analysis than Mr Lister’s discovery of the double aplanatic
foci and variable aberration of achromatic object-glasses having
their inner curves in contact? to say nothing of the admirable
application of which it is capable. If I was a mathematician,
I should feel my honour piqued that it had been made by ex-
periment. It is quite plain that compound microscopes and
erecting eye-pieces are only part and parcel of the subject of
telescopes, and worthy of the same attention. Nothing which
concerns the exact sciences can in my opinion be frivolous or
unimportant,—a mere subtlety or conundrum having the charm
of exactitude about it must always be respectable, though it
may be of no positive utility.

A great deal has been said about the insignificance of mi-
croscopes, and that too much has already been written about
them. Such opinions proceed naturally enough from the per-
sons who are interested in opposing the new improvements,
and are certainly highly worthy of a country where the exact.
sciences seem to be getting out of fashion, and where the ¢ ex-
perimental ones take precedence of them.

LamBetn, April 1, 1831.

Art. VII—On the Specific Heats of some of the Metals, with
an exposition of some erroneous Determinations by MM.
Dulong and Petit ; and an examination, as to the Metals,
of the important law, that the ultimate particles of simple
bodies have all the same capacity for Caloric. By R. Porter,
Esq. Junior. Communicated by the Author.

Ix the course of my optical inquiries, it became necessary for
me to learn the capacities of steel and speculum metal for calo-

76 Mr Potter on the SpecifieHeats of Metals, &c.

ric. The results of my experiments gave me numbers so much
smaller than I had expected’from a review of Mr Dalton’s de-
terminations for iron, copper, and tin, that I resolved to seize
the opportunity of my first leisure time to enter into further
investigations of the specific heats of the metals generally.

Mr Dalton has given a very extensive table of the specific
heats of different substances, which in the metals are little dif-
ferent from the older determinations of Irvine, Wilcke, and
Crawford; but these numbers are, I think, frequently too
great by 3 to yy part, for which allowance should be made
when these tables are used. |

MM. Dulong and Petit, who have so ably examined the
phenomena of cooling bodies, presented also to the Academy
of Sciences in 1819* an essay, of which the principal purport
is the specific heats of certain of the metals determined by them,
coupled with important theoretical considerations. In the
course of their essay they take the opportunity to stigmatize
as exceedingly erroneous, all the results of former chemists ex-
cept those of their own countrymen. But before passing so
sweeping a censure, it would have been as well if they had
been sufficiently circumspect in their own experiments, to pre-
vent a recoil of it with double force on their own labours. The
method they made use of in this instance to find the capacities:
of the metals for caloric is the following :—The metal to be
examined was reduced to a very fine powder, and pressed’
closely into a small and very thin cylinder of silver, having a_
thermometer placed in its axis. When the whole was adapted
to a suitable apparatus, the capacity was deduced from the
rate of cooling indicated by the thermometer ; the quantity of
even the heaviest metals required for the experiment being
something less than an ounce English. It must be clear to
every one, that, when we resort to intricate or elegant methods
of experimenting, our vigilance and suspicion ought to be awak-
ened, particularly when our results differ suddenly from the
determinations of those who have used simpler apparatus ; and —
it appears unaccountable, that, when MM. Dulong and Petit
found their results for most of the metals of less capacity than
silver differ so greatly from the determinations of Mr Dalton,
of Wilcke, and of Crawford, they did not seek to prove them

* See Annales de Chimie et de Physique for 1819.

Mr Potter on the Specific Heats of Metals, &c. 717

by the other mode, and also that they did not immediately con-
sider the possible effect of their cylinder of silver, and of the
bulb of the thermometer necessary to be used. . As the matter
stands, their table will be found to contain as great a sia
tion of error as any published on the subject.

In the method of determining the specific heats of solids not
acted upon chemically by water, by immersing them in a known
weight of that liquid at another temperature, and then noting
the resulting temperature, it is clear that we have two ways of
performing the experiment,—the one where the solid is hotter
than the fluid, and the other the reverse; and the attendant:
errors, when we compare the results, are, as might be expect-
ed, generally in opposite directions, and may thus be rendered
serviceable in pointing out.the precautions necessary to be used,
and the allowance to be made in deducing. the correct deter-
minations.

The great source of error in all experiments of this descrip-
tion is the alteration in temperature of the materials during
the process of the experiment; for it is necessary that either the
fluid or the solid body be at a temperature much above that
of the air and surrounding objects. From the capacity of
water for equal weights being so much greater than that of the
metals, the influence of the alteration in temperature in pro-
ducing error is much greater when the cold metal is immersed
in tepid water than in the other way; and guratey dexterity
and more precautions are required.

In some of my first trials I used a vessel of tin-plate to con-
‘tain the water, and obtained the following results :—

Specificheatdeduced Specificheat deduced
Quantity from immersing the from immersing the
of the metal at 212° in an metal at 55° in an

metal used.,- equal weightofwater equal weight of water
at common temps. at about 103°

For equal Forequal Forequal For equal
weights. bulks. weights. - bulks.

Hard steel, 116.114 .0z .1026 800

Speculum |

metal,» » G3 0z.—- .070..-—-«.62
Hard steel, 2014 grs 113 8814 . .200 1.56
Speculum |

metal, ~ 2099 — .075- 6675 293 198

78 Mr Potter on the Specific, Heats of Metals, Se.

The great discordance in the results given by the reverse

ways convinced me that the tin-plate vessel was an insufficient .

apparatus ; and also in making use of the second method, or,

adding the cool metal to the heated water, that considerable —

care and dexterity would be necessary to gain correct results.
In lieu of the tin-plate vessel, my later experiments have been
made with a compound one, consisting of an inner vessel of
thin varnished linen surrounded by a cles and friezed woollen
cloth, and both these fixed in an earthen-ware one, of a dimen-
sion just sufficient to admit them. This compound vessel was
capable of holding about 3500 grains of water. In making
use of what I shall call the first method, I found this vessel
quite sufficient, without need of any other particular precau-
tion except that of going as quickly through the experiment as
possible ; but, in attempting the second method, I found the
results still very unsatisfactory, until I adopted the plan of sur-
rounding the compound vessel with water of nearly the’ tem-
perature of that about to be experimented with, and also of
preventing the evaporation from the surface by using a cover
of varnished linen cloth with the same sort of woollen cloth
before-mentioned attached toit. In this manner, and by tak-
ing care to raise the cover no more than necessary when the
metal was introduced, I got results which accorded as near
_ with those got on the other method as I had any reason to
expect. We might anticipate some little difference in the re-
sults of the two methods from the alterations in capacity arising
from temperature ; but a limit of error must be allowed much
greater than any effect arising from this cause, between $2°
and 212° Fahrenheit.

In taking the specific heats on the first method, it is neces-
sary, when great correctness is wanted, to have the solid in one
piece only, and presenting as small a surface as possible, to
prevent to the utmost the loss of heat whilst it is in the course
of being transferred from the boiling to the cold water. In
this respect, MM. Dulong and Petit committed an oversight
in experiments published in a previous paper to the one just
alluded to; and it is on this account that I consider the num-
bers found for gold, silver, and copper, in the table below, on
the first method, as much too small ; because for these metals

Mr Potter on the Specific Heats of Metals, §e. 79

I used British coins, where it was needful that there should be
many pieces to have the requisite weight. This, it will be
readily seen, is rather an advantage than a disadvantage in using
the second method. I have moreover found, that, with a ves-
sel of the capacity of the above, it was necessary to operate
with at least about 1200 grains of metal to perform a good
experiment. The numbers in the table for lead were obtained
by immersing 8000 grains of the metal in 2000 grains of water.
As this metal appears to have the smallest capacity of any
metal known, I was anxious to determine it with accuracy, and
particularly from having previously made several trials which
did not accord very well together. When it can be practised,
I should recommend future experimenters to follow the same
plan, and use a greater weight of the substance which has the
_ least capacity, more especially when they wish to obtain good
approximations. These experiments show that .032 is very
near the correct number for lead at common temperatures, as
Mr Dalton’s later experiments indicate.—See the Appendix to
the first part of the second volume of his chemical work.

The thermometer which I have used I proved by breaking
the column of mercury in the tube, and measuring the number
of degrees which the separated length subtended in different
parts of the scale, and found it very nearly correct between
32° and 212°. )

g Specific heats from Bs en ae
Weight & the first method, or the metal at about
used. ‘G. the.metal at 212° 450 immensed if
;, immersed in water water. at about
4 at about 50°, 110°.
=
Z For equal weights. Forequal weights.
Steel, (hard,) 2014 grs. 8 1024 15
.1086
(soft,) / .1080 .
Zinc,’ 1932 1 0912 1034
.0948
Copper, 2047 11 .0868 .1014
Silver, 117 11 .0601 0669
Tin, “ 2111 2 .0596 0542

- ani 1 0597 - 0588

80 Mr Potter on the Specifie Heats of Metals, §c.

Gold, - 1414 12 0875 0509
Bismuth, 1650. 3 .0390 .0393
Lead,” -'’ 8000)" “* 32 | 0328
gra me . 0886
concen 1 0307 ; |

I have made several trials with wrought i iron, which Pit
indicate that there is a ‘slight difference between its capacity
and that of steel; but I am not yet prepared to ‘speak posi-
tively on the amount of difference. ___

Reviewing the above table, I think we may conclude that
the capacities in the first column of the following one are very
near the truth for common temperatures. In the other columns
I have given Mr Dalton’s numbers, and those of MM. Dulane
and Petit for the same metals,

Specific edie: i

Specific heats Specific heats according to

See O° a ae paris
Tron, 110 13 0.1100
Zinc, .098 10 0.0927
Copper, 096 Ll 0.0949 .

. Silver, .063 08 0.0557
Tin, 056 .054? 07 0.0514... -
Gold, 046 05 0.0298 ...
Bismuth, .039 04 0.0288
Lead, 032 04 .032 0.0293

Here we see the great -incorrectness of MM. Dulong and

Petit’s numbers for gold and bismuth, and how little room
they had for pronouncing so decidedly on the labours of others.
And if the relative weights of the atoms of the metals had
been at the time sufficiently nearly ascertained, we see that
there is no proportion of error in Mr Dalton’s numbers, as they

assert, which would have prevented him recognizing in them .
the law respecting the capacity for heat of the ultimate particles ,

of gaseous bodies, which he has advanced in his new system
of chemical philosophy. This law, which he appears to have
noticed in several of the gases, he unfortunately expected to
hold without modification in all, whether simple or compound-

_ Mr Potter on the Specific Heats of Metal. 81

ed, and had anticipations that similar laws would be found ir
liquids and solids generally.

It has since been maintained, on the ground of experiment,
by the above-named French philosophers, that the law is only
applicable, in the first instance, to the atoms of simple bo-
dies, and requiring some modifications for those of compound
ones which they had not been able to ascertain. The nature
of caloric and its connexion with ponderable matter are still
the subjects of so much uncertainty and dispute, that much
more information will be necessary before we can arrive at
even a tolerable view of its general properties, and the’ laws
which they obey. But that Mr Dalton’s proposition has a
basis in nature there can be no reasonable doubt, though, even
with MM. Dulong and Petit’s modification and limitation,
there is still ground for suspecting that we are not yet within
sight of the general law. And to this effect Mr Dalton has a
‘remark in the appendix to the Ist part of the 2d volume of
the new system of chemical philosophy.

However, the law as enunciated by the French philosophers,
** that the atoms of all simple bodies have the same capacity
for heat,” when applied to the class of the metals, holds, I
find, with singular fidelity in comMoN TEMPERATURES, ex-
cepting in one very remarkable case, namely, that of silver.
Whilst the exception remains, the law cannot be said to be es-
tablished, much less can MM. Dulong and_ Petit in the least
be said to have proved their proposition, as they have taken for
the atomic weights numbers completely arbitrary, without re-
ferring either to the opinions of chemists or the results of
analyses. . Whence they obtained their numbers I shall now
show. They appear to have appropriated such portions of Ber-
zelius’s numbers as suited their experiments.. Thus, for bismuth
they, have taken a of his pnbete for lead 3 2s for gold 3, for
tin 1, for silver 4, for zinc }, for tellurium }, for copper 3,
for nickel 3, i iron 3, and for cobalt. £ of his number.
Where a theory of definite proportions only is referred to,.
such a proceeding might be warranted, but not so, on any
ground, when atoms are considered without direct reference
to analyses; and not having done this, they can only. be said

NEW SERIES, VOL. v. NO I. JULY 1831. F

82 _ Mr Potter on the Spegific Heats of Metal.

to have shown the probability. that such a law did exist in na-

ture.
The proposition may be: placed i in view under the algebraic

formula ae — 1, where ec denotes the capacity for heat, taken

with respect to some received standard, d is the relative atomic
weight similarly considered, and m is a constant, whose value
depends on the scales we adopt for the atomic weights and the
capacities. |
Taking, in the scale of capacities, that of water, for unity,
and in that of the atoms the weights of hy drogen as unity, and
oxygen 7, I find the value of m to be very nearly 2.75, and
on these data I have calculated the weights of the atoms of
the metals in the table below, where will be seen, in the re-
spective columns, the numbers deduced from chemical ana-
lyses by Mr Dalton, Berzelius, and Dr Ure, and also those
used by MM. Dulong and Petit, but the last, as well as those
of Berzclius, I have reduced to the hydrogen scale, taking
oxygen at 7. In Dr Ure’s, 1-15th part must be allowed, as

' he adopts 7.5 as the weight of the atom of oxygen.
Weights of

Spec: heats “ome for Weights of the atoms according to Weights used
for equal the formula by Dulong
o d = Dalton. Berzelius. Ure. and Petit. yt
Iron, 110 25. 25. 47.49 28. 23.74
Zine, .098 2B. 141 V9. 56.45 84. 28.21
Copper, .096 28. 560r28? 55.39 64. 27.69
Silver, .063 44), 90. 189.22 110. 47.25
Tin, .056 49. - §2. 102.94 58. 51.45
Gold, .046 60. 60. + 174.02 200.. 87.01.
Bismuth, .039 70. 62. 124.16... 72. 93.10
Lead, .0382 86. 90. 181.23. 104. 90.65

There is not here any more difference between the weights
of the atoms deduced from the specific heats, and those de-
duced from analyses according to Mr Dalton, than must be
allowed for the limit of error in either way, excepting in ‘those
for copper and silver, where the number from analyses is dou-
ble the other. But in the analysis of the oxides and salts of

the former metal, I see nothing which militates.against the |

Mr Matheson on a new mode of constructing Harbours. 83

supposition that the smaller number is the correct one, Mica
Mr Dalton appears still to consider it doubtful. Dr Wol-
laston’s equivalent for copper was exactly four times that of
oxygen. In silver we are not entitled to draw a similar conclu-
sion, and there is no analysis of an oxide or salt of silver
which would entitle us to consider its atom half the weight
Mr Dalton has it. Hence we are reduced to the alternative,
that there is either another oxide of silver containing a larger
‘proportion of oxygen than the one commonly known, and which
has never yet been detected by chemists, or this metal must
stand an exception to a law which holds so remarkably with
the others. If, as I expect, the common oxide of silver will
prove to be a sub-oxide, we shall here have an exemplification
of the unexpected assistance which abstruse inquiries often lend
to those branches of science where it was least anticipated.
Lith May 1831.

Arr. VIII.—Observations on a new mode of constructing Har-
bours: By Witt1am Marueson, Civil-Engineer. Com-
municated by the Author.*

‘T nx importance of good harbours to a mercantile country will be
universally admitted, and the commercial eminence great Bri-
tain has attained, has naturally directed the attention of per-
sons interested, in the extension of her trade, to the improve-
ment of the surrounding harbours; and perhaps in no way has
the skill and ingenuity of engineers been more extensively
employed, or more usefully directed. Many great works have »
been executed at an enormous expence, and some of them have
succeeded more or less, to the expectation of the parties.

The erection of works within tide mark must always be
attended with trouble and additional expence, and it is the more
to be lamented after such expensive operations have been carried
into effect, that the whole benefit of them should be frustrated
by some unforseen circumstance, which has too frequently hap-
pened in such operations.

Of these latent difficulties, none has had a more powerful in-
fluence than the tendency of the tide, or the motion of the

* Read before the Royal Society of Edin. 1831.

/

84 Mr Matheson on a new mode of constructing Harbowrs.

waters in particular situations, to silt or sand up spaces which
have been enclosed, and upon which, by means of such ince
a change has been made upon the currents. ap

This tendency to sand up is peculiar to every situation,
where quantities of sand are under the-influence of the tide or
the motion of the waters, and liable to be carried from place to
place in mechanical combination with the water, either by means
of the ebbing and flowing of the tide, or of the motion given to
it by particular currents; or, by what is the most powerful of
all, the motion given to it by the violence of the winds. .

This motion of sand is generally in a direction opposite to
that in which the wind is blowing, as may be seen in standing
pools or lakes, where the sand, when the water is agitated by
the wind, takes shelter under the banks of the weather side ;
but this will be more particularly explained afterwards.

In consequence of this tendency, the mouths of all rivers,
and flat shores, and all bays and estuaries into which the tide
rushes with violence, are more or less subject to the accumu-
lation and shifting of sand banks, if sand is to be found in such
situations. Examples of this may be seen by examining the
harbours of Aberdeen, Dundee, Dublin, and a variety of others ;
and it may be generally asserted, that no harbour was ever
erected upon a river that was not more or less subject to the
inconvenience of shifting sand banks at the mouth of the river,
or of being itself sanded up.

The writer of these observations having been employed at an
early period of life in works connected with harbours, his at-
tention was particularly directed more than.thirty years ago, to
the annoyance met with by the sanding up of harbours; and he
saw the object frustrated, after the most expensive works had
been erected, in the hope that they would answer every purpose
expected from them. ,

Never losing sight of the evil which he had observed, nor
ever ceasing to feel a desire to have it removed, he at last. by
mere accident, discovered in the harbour of Pulteney Town, a
circumstance which led him to a corrective theory upon the
subject.

An opening had been left in the inner pier. for upwards of a
' year, while the other operations of building were going on, and

Mr Matheson on a newo mode of constructing Harbours. 85

through which opening the receding tide, assisted by the land

stream, passed into the harbour, and swept round and again

passed out at its mouth. By this action of the tide, the har-

bour was kept perfectly free from any tendency to sand up; but

in the course of a very short period, after the works were finish-

ed, and this opening closed up, in completing the harbour, the

sand accumulated in it to such a degree as to make it inac-
cessible to vessels of even very small tonnage, and to cause the

outlay of a large sum of money in the erection of an outer harbour
which it is probable will be visited with the like obstructions, if
they have not already taken place. :

“The practical hint thus afforded induced the writer to form
the idea of erecting the necessary works for sea harbours, with
artificial openings, so constructed as to enable the waters still to
rétain their natural motion, and by that means to avoid eddies
and stagnation, by the latter of which the sand and alluvion are
deposited, and by the former of which the deposition is shift-
ed and whirled from place to place.

His plan, therefore, may be very shortly described. Where-
ever it may be necessary to erect a harbour, or to extend the
works of one in a situation where sand or alluvion may be likely
to accumulate, he proposes, after laying a solid foundation of
stone, to make the next range of building consist of a succession
of arches of such a height of opening as not to disturb any class
of vessels that may frequent the harbour, while they are pro-
tected and sheltered by the solid building erected over these
arches, and at the same time the openings shall be so proportion-
ed to the depth of water, at the different, points of the building,
as to allow the tide to pass freely through.

To enter into any detail as to the particular mode of con-
structing the works or of forming the arches, &c. is quite un-
necessary here, as these must vary according to circumstances.
It is enough, if it is admitted that walls with arches may be
constructed under water, as well as solid walls ; because so much -
being granted, it will appear sufficiently obvious that the motion
of the tide, either in approaching or receding, will naturally pass
through these arches, and carry with it both in advancing and re-
tiring, whatever is mechanically united with it, and the agitation

86 Mr Maccullagh on theeIntensity oe Light.

kept up upon the bottom of the harbour will — the sand
being deposited.

. There is another mode already hinted at of sand being coiled |

ss which the peculiar construction of harbours here described _ .

is equally well calculated to counteract. It isa fact well known

to some of those who attentively observe the operations of
nature, that all floating substances, especially such as do not
rise above the surface of the water, approach the shore with a
land wind, and recede from it by a contrary wind. ‘This seems
to arise from the violence of the wind. upon the water causing -
the surface water to pass from the shore, and the under water to _
approach it, to supply its place by means of an opposite current.
This under current is the more conspicuous in its operation,
when the tide flows or ebbs in a contrary direction to that of
the wind, and the floating substances carried along are according-
ly deposited.

‘The consequence is, that, wherever large solid buildings are
erected in a current of water, which has a tendency to sand up,’
and where these buildings pass along the shore, the wind from
the shore that passes over them causes a sand bank to be formed
seaward of the building, and to bring it directly into the
‘mouth of the harbour, if it happens to be in the line of that
building. This fact is strongly exemplified by the sand already
accumulated at the back of the wet docks at Leith, or the stone
pier at Newhaven, and in many other situations.

9, Dean SrreeEr, Eprn.
30th Nov. 1830.

Art. IX.—On the Intensity of Light when the vibrations are
elliptical. By James Maccutziacu, Esq. Communicated
by the Author.

Accorptné to the opinions commonly received, the intensity

of light, in the undulatory hypothesis, is proportional to the

vis viva, which again is proportional to the square of the
greatest velocity. Now the greatest velocities will be the same
in an ellipse and a right line which have the same period, if the
greater axis of the ae be equal to the whole extent of the

Mr Maccullagh on the intensity of Light. 87

latter ; so that in elliptic vibrations the intensity would be in-
dependent of the minor axis, which is far from being true. I
would propose the integral fv * d t—so remarkable for its me-
chanical properties—as the measure of the intensity, the inte-
gral being extended to the whole time of a vibration. This
gives precision to the notion of vis viva, and leads moreover
to an elegant result; for if a and 6 denote the semiaxes of the.
ellipse, and ‘1’ the time of vibration, the integral, by an easy

2
calculation, will be found equal to ~~ (a°-+8*), showing that

for the same colour the intensity is proportional to the sum of
the squares of the semiaxes, and that for different colours it in-
creases with the rapidity of the vibrations, as it would be natural
to suppose @ priori. tat J

This theorem assigns very simply the reason why two por-
tions of light polarized at right angles do not interfere; but
to show this, it will be necessary to lay down the following
general rule for compounding rectilinear vibrations having the
same period, whatever be the difference of their origins and
directions.

Let AA’ and BB’, Plate I. Fig 3, bisecting each other at O,
represent in extent and iaiess the vibrations to be com-
pounded, and suppose C and D to be two simultaneous positions
of the moving molecule, which it would have in virtue of each
vibration singly. Complete the parallelograms O E and O P,
and through P describe an ellipse having O for its centre; and
touching the sides of the parallelogram O E;, this ellipse will -

represent the resulting vibration ; it will have the same period
as the component ones, and equal areas will be described in
equal times about its centre..

To apply this construction to the case proposed, it is ne-
cessary to show that when O A and-O B are constant and at
right angles to each other, the intensity of the elliptic vibra-
tion, or the sum of the squares of the semiaxes, is independent
of the difference of OrgD, or of the position of the popits C
and D.

Now in an ellipse when a perpendicular from the centre on a |
tangent makes an angle ? with the paler axis, the square of its
length is equal to a’ cos’ 9 +6’ sin’ 9. If 2 be the angle which

88 «Mr Dalton.on the, Vision of Colours.

the major axis. makes with-O: A, it will make its RP i
with OB, and we shall have.

O A? = a? cos? 9 + 6% sin? 9,

O B? — a* sin? 2: + 6? cos? 9, : ado

and therefore O A? + O B? =a? 4+ 6%. Hence the intensity is
independent of the difference; of , porigin, and therefore the nye
do not interfere.

This remarkable circumstance is commonly apcaiuisted for ey
observing, that since the component velocities are at right
angles to each other, the square of the actual velocity must be
the sum of their squares ; but this proves the proposition only
when the greatest velocities are simultaneous, which happens
only in the cases of a complete accordance or of a’ difference of
a semi-undulation in the interfering portions.

It may be observed also, that the method usually given for
finding the intensity of the vibration resulting from two or
more rectilinear vibrations proceeds upon no certain grounds.
All the vibrations may be reduced to two in rectangular diree-
tions, the expression for the square of the velocity in each of
those directions consisting of two parts, one of which is constant,
and the other depends on the cosine of an are increasing pro-
portionally to the time; the square of the resultant velocity,
therefore, consists also of a constant part, and a part depending
similarly on the time, and it is assumed that the intensity of
the resulting vibration is proportional to the former, which is
true only in the very particular cases just mentioned, if the in-
tensity be measured by the square of the greatest velocity.

_ This assumption, however, gives a correct result ; and the
reason that it does so is obvious from the principle laid down
in the commencement: for if the expression for the square of
the velocity be multiplied by the differential of the time and

integrated, the variable part will vanish. when the ince is’

extended to the whole time of a vibration.

Art. X.—Extraordinary facts relating to the Vision of Co-
.lours: with Observations. By Mr Joun Datron.*

Ir has been observed, that our ideas of colours, sounds, tastes,
Sa From Memoirs of Lit, and Phil. Soc. of Manchester, vol y. part i.

eS eS eS Se Oe

a

_Mr Dalton on the Vision of Colours. 89

&c. excited by the same object may be very different in them-
selves, without our being aware of it; and that we may never-
theless converse intelligibly concerning such objects, as if we.
were certain the impressions made by them on our minds were
exactly similar. All; indeed, that is required for this purpose,
is, that the same object should uniformly make the same 1m-
pression on each mind ; and that objects which appear different
to.one should be equally so to others. It: will, however, scarce-
ly be supposed, that any two objects, which are every day be-
fore us, should appear hardly distinguishable to one person,
and very different to another, without the circumstance imme-
diately suggesting a difference in their faculties of vision; yet
such is the fact, not only with regard to myself, but to many
others also, as will appear in the following account.

I was always of opinion, though I might not often mention
it, that several colours were injudiciously named. ‘The term
pink, in reference to the flower of that name, seemed proper
enough; but when the term red was substituted for pink, I
thought it highly improper ; it should have been blue, in my ©
apprehension, as pink and blue appear to me very nearly ,
allied ; whilst pink and red have scarcely any relation.

In the course of my application to the sciences, that of optics
necessarily claimed attention; and I became pretty well ac-
quainted with the theory of light and colours before I was
apprized of any peculiarity in my vision. I had not, however,
attended much to the practical discrimination of colours, owing,
in some degree, to what I conceived to be a perplexity in their
nomenclature. Since the year 1790, the occasional study of
botany obliged me to attend more to colours than before.
With respect to colours that were white, yellow, or green, I
readily assented to the appropriate term. Blue, purple, pink,
and erimson appeared rather less distinguishable ; being accord+
ing to my idea, all referable to blue. I have often seriously
asked a person whether a flower was blue or pink, but was
generally considered to be in jest. Notwithstanding this, I was
never convinced ofa peculiarity in my vision, till I accidentally
observed the colour of the flower of the Geranium zonale by
candle-light, in the autumn of 1792. The flower was pink,
but it appeared to me almost an exact sky-blue by day ; in

90 -—s- Mr Dalton on the Vision of Colours. .

candle-light, Biilacigs it was astonishingly changed, not having

then any blue in it, but being what I called red, a colour
which forms a striking contrast to blue. Not then doubting

but that the change of ‘eolour would be equal to all, I requested
some of my friends to observe the phenomenon ; when I was
surprised to find they all agreed, that the colour was not ma-
terially different from what it was by day-light, except my
brother, who saw it in the same light as myself. ‘This observa-

tion clearly proved, that my vision was not like that of other |

persons ; and, at the same time, that the difference between
day-light and candle-light, on some colours, was indefinitely
more perceptible to me than toothers. It was nearly two years
after that time, when I entered upon an investigation of the
subject, having procured the assistance of a friend, who, to his
acquaintance with the theory of colours, joins a practical know-
ledge of their names and constitutions.’ I shall now proceed to
state the facts ascertained under the three following heads:

I. An account of my own vision. .

II. An account of others whose vision has been foiswly simi-
lar to mine.

11]. Observations on the probable cause of our anomalous

vision.

I. Of my own vision.—It may be proper to observe, that I
am short-sighted. Concave glasses of about five inches focus
suit me best. I can see distinctly at a proper distance; and
am seldom hurt by too much or too little light; nor yet with
long application.

My observations began with the solar spectrum, or colour-
ed i image of the sun, exhibited in a dark room by means of a
glass prism. I found that persons in general distinguish six
kinds of colour in the solar image ; namely, red, orange, yel-
low, green, blue, and purple. ' Newton, indeed, divides the pur-
ple into indigo and violet ; but the difference between him and
others is merely nominal. ‘To me it is quite otherwise :—I
see only ¢wo or at most three distinctions. ‘These I should call

yellow and blue ; or yellow, blue, and purple. My yellow com- -

prehends the red, orange, yellow, and green of others; and
my blue and purple coincide with theirs. That part of the
image which others call red, appears to me little more than a

OE a

‘

Mr Dalton on the Vision of Colours. 9]

shade, or defect of light; after that the orange, yellow, and
green seem one colour, which descends pretty uniformly from
an intense to a rare yellow, making what I should call different
shades of yellow. ‘The difference between the green part and
the blue part is very striking to my eye: they seem to be
strongly contrasted. That between the blue and purple is
much less so. The purple appears to be blue much darkened
and condensed. , In viewing the flame of a candle by night
through the prism, the appearances are pretty much the same,
except that the red extremity of the image appears more vivid
than that of the solar image.

I now proceed to state the results of my observations on the
colours of bodies in general, whether natural or artificial, both
by day-light and candle-light. I mostly used .ribbands for
the artificial colours.

Red by day-light.—Under this head I include crimson, scar-
let, red, and pink. All crimsons appear to me to consist chiefly
of dark blue; but many of them seem to have a strong tinge
of dark brown. I have seen specimens of crimson, claret, and
mud, which were very nearly alike. Crimson has a grave ap-
pearance, being the reverse of every shewy and splendid co-
lour. Woollen yarn dyed crimson or dark blue is the same to
me. Pink seems to be composed of nine parts of light blue,
and one of red, or some colour which has no other effect than
to make the light blue appear dull and faded a little. Pink —
and light blue, therefore, compared together, are to be distin-
guished no otherwise than as a splendid colour from one that
has lost a little of its splendour. Besides the pinks, roses, &c.
of the gardens, the following British fora appear to me blue ;
namely, Statice Armeria, Trifolium pratense, Lychnis Flos-
cuculi, Lychnis dioica, and many of the Gerania. The co-
lour of a florid complexion appears to me that of a dull,
opaque, blackish blue, upon a white ground. A solution of
sulphate of iron in the tincture of galls (that is, dilute black
ink) upon white paper, gives a colour much resembling that
of a florid complexion. It has no resemblance of the colour
of blood. Red and scarlet form a genus with me totally,
different from pink. My idea of red I obtain from vermilion,
minium, sealing-wax, wafers, a soldier’s uniform, &c. These

;

92 Mr Dalton on the Vision of Colours.

seem to have no blue whatever in them. Scarlet has a more’
splendid appearance than red. \ Blood appears to me red; but —

it differs much from the articles mentioned above. It is much
more dull, and to me is not unlike that colour called bottle-
green. Stockings spotted with blood or with dirt would
scarcely be distinguishable.

Red by candle-light.—Red and scarlet appear much more
vivid than by: day. Crimson loses its blue and becomes yel-
lowish red. Pink is by far the most changed ; indeed it forms

an excellent contrast to what it is by day. No blue now ap-

pears; yellow has taken its place. Pink by candlelight
seems to be three parts yellow and one red, or a reddish yel-
low. The blue, however, is less mixed by day than the yel-
Jow by night. Red, and particularly scarlet, is a superb co-
lour by candle-light ; but by day some reds are the least so
imaginable: I should call them dark drabs.

Orange and yellow by day-light and candle-light, —I do not
find that I differ materially from other persons in regard to
these colours. I have sometimes seen persons hesitate whe-
ther a thing was white or yellow by omnes when to me
there was no doubt at all.

Green by day-light.—I take my standard idea from grass.
This appears to me very little different from red.. The face of
a laurel-leaf ( Prunus Eauro-cerasus ) is a good match to a stick
of red sealing-wax; and the back of the leaf answers to the
lighter red of wafers. Hence it will be immediately conclud-

ed, that I see either red or green, or both, different from other —

people. The fact is, I believe that they both appear: different

to me from what they do to others. Green and orange have
much affinity also. Apple green is the most pleasing kind to
me; and any other that has a tinge of yellow appears to ad- -

vantage. I can distinguish the different vegetable greens one
from another as well as most people; and those which are
nearly alike or very unlike to others are so to me. A decoc-
tion of Bohea tea, a solution of liver of sulphur, ale, &c. &e.

which others call brown, appear to me green. Green woollen —
cloth, such as is used to cover tables, appears to mea dull,

dark, brownish red colour. A mixture of two parts mud and

one red would come near it. It resembles a red soil just turn: |

>

_Mr Dalton on the Vision of Colours. 98

ed up by the plough. When this kind of cloth loses its co-
lour, as other people say, and turns yellow, then it appears to
mea pleasant green. Very light green paper, silk, &c. is
white to me.

Green by candle-light.—I agree with others, that it is diffi-
cult to distinguish greens from blues by candle-light ;. but,
with me, the greens only are altered and made to approach
the blues. It is the real greens only, that are altered in my
eye; and not such as I confound with them by day-light, as
the brown liquids above-mentioned, which are not at all tinged
with blue by candle-light, but are the same as by day, except
that they are paler.

Blue by day-light and candle-lig ht. ink apprehend this colour
appears very nearly the same to me as to other people, both
by day-light and candle-light.

.Purple by daylight and candle-light—This seems to me a
slight modification of blue, . I seldom fail to distinguish pur-
ple from blue ; but should hardly suspect purple to be a com-
pound of blue and red. ‘The difference between day-light and
candle-light is not material. —

Miscellaneous observations.—Colours appear to me much
the same by moon-light as they do by candle-light.

Colours viewed by lightning appear the same as by day-
. light ; but whether exactly so, I have not ascertained.

Colours seen by electric light appear to me the same as by
day-light. That is, pink appears blue, &c.

Colours viewed through a transparent sky-blue liquid, by
candle-light, appear to me as well as to others the same as_ by
day-light.

Most of the colours called drabs appear to me the same by |
day-light and candle-light.

A light drab woollen cloth seems to me to resemble a odie
green by day. These colours are, however, easily distinguish-
ed by candle-light, as the latter becomes tinged with blue,
which the former does not. I have frequently seen colours of
the drab kind, said to be nearly alike, which oan to me
very different.

My idea of brown I obtain from a piece of iwahise: paper
heated almost to ignition. This colour by day-light seems to

94 Mr Dalton on the Vision of Colours.

have a great affinity to green, as may be imagined from what
I have said of greens. Browns seem to me to be very diver-
sified; some I should call red :—dark brown woollen cloth I
should call black. "

The light of the rising or setting sun has no padtioulan of.
fect; neither has a strong or weak light. Pink appears rather
duller, all other circumstances alike, in a’cloudy day.

All common combustible substances exhibit colours to me in
the same light; namely, tallow, oil, waz, pit-coal.

My vision has always been as it is now. '

II. An account of others whose vision has been found similar
to mine.—It has been already observed that my brother per-
ceived the change in the colour of the geranium such as myself.
Since that time having made a great number of observations on
colours, by comparing their similarities, &c. by day-light and
candle-light, in conjunction with him, I find that we see as
nearly alike as any other persons do. He is shorter eighten
than myself.

As soon as these facts were ascertained, T conceived the de:
sign of laying our case of vision before the public, apprehend-
ing it to be a singular one. I remembered, indeed, to have
read in the Philosophical Transactions for 1777, an account
of Mr Harris of Maryport in Cumberland, who, it was said,
** could not distinguish colours ;” but his case appeared to be
different from ours. Considering, however, that one anomaly
in vision may tend to illustrate another, I reperused the ac-
count; when it appeared extremely probable that, if his vi-
sion had been fully investigated, and a relation of it given in
the first person, he would have agreed with me. There were
four brothers in the same predicament, one of whom is now
living. Having an acquaintance in Maryport, I solicited him —
to propose a few queries to the survivor, which he readily did,
(in conjunction with another brother, whose vision has no-
thing peculiar,) and from the answers transmitted to me, I.
could no longer doubt of the similarity of our cases. To ren-’
der it still more circumstantial, I sent about twenty specimens”
of different coloured ribbands, with directions to make obser-

Mr Dalton on the Vision of Colours. 95

vations upon them by day-light and candle-light : the result
was exactly conformable to my expectation.

It then appeared to me probable, that a considerable num-
ber of individuals might be found whose vision differed from
that of the generality, but at the same time agreed with my
own. Accordingly, I have since taken every opportunity to
explain the circumstances amongst my acquaintance, and have
found several in the same predicament. Only one or two I
have heard of who differ from the generality and' from us also.
It is remarkable that, out of twenty-five pupils I once had, to ~
whom I explained this subject, two were found to agree with
me; and, on another similar occasion, one. Like myself, they
could see no material difference betwixt pink and light blue by
day, but a striking contrast by candle-light. And, ona fuller
investigation, I could not perceive they differed from me mate-
rially in other colours. They, like all the rest of us, were not
aware of their actually seeing colours different from other peo-
ple; but imagined there was great perplexity in the names as-
cribed to particular colours. I think-I have been informed
already of nearly twenty persons whose vision is like mine.
The family at Maryport consisted of six sons and one daugh-
ter; four of the sons were in the predicament in question.
Our family consisted of three sons and one daughter who ar-
rived at maturity; of whom two sons are circumstanced.as I
have described. ‘The others are mostly individuals in families,
some of which are numerous. I do not find that the parents
or children in any of the instances have been so, unless in one
case. Nor have I been able to discover any physical cause
whatever for it. Our vision, except as to colours, is as clear
and distinct as that of other persons. Only two or three are
short-sighted. It is remarkable that I have not heard of one
female subject to this peculiarity.

From a great variety of observations made’ with many of
the abaveaienioned persons, it does not appear to me that
we differ more from one another than persons in general do.
We certainly agree in the principal facts which characterize
our vision, and which I have attempted to point out below.
{t is but justice to observe here, that several of the resemblan-
ces and comparisons mentioned in the preceding part of this

96 Mr Dalton on the Vision of Colours.

paper were first suggested to me by one or other of the PArHiets
and found to accord with my own ideas.

Characteristic facts of our vision.—1. In the +e specae
three colours appear, yellow, blue, and purple. The two for-
mer make a contrast; the two latter seem to differ more in de-
gree than in kind.

2. Pink appears, by day-light, to be sky-blue a little ee
by candle-light it assumes an orange or yellowish appearance,
which forms’ a strong contrast to blue.

3. Crimson appears a muddy blue by day; and crimson
woollen yarn is much the same as dark blue.

4. Red and scarlet have a more vivid and flaming appearance :

by eandle-light than by day-light.

5. There is not much difference in colour between a stick of
red. sealing-wax and grass, by day.

6. Dark green woollen cloth seems a muddy red, much
darker than grass, and of a very different colour.

7. The colour of a florid complexion is dusky blue.

8. Coats, gowns, &c. appear to us frequently to be badly
matched with linings, when others say they are not. On the
other hand, we should match crimsons with claret or mud;
pinks with light blues; browns with reds ;. and drabs with
greens.

ference is much less by candle-light than by day-light.

III. Observations tending to point out the cause of our ano-
malous vision.—T he first time I was enabled to form a plausible

idea of the cause of our vision, was after observing that a sky.

blue transparent liquid modified the light of a candle so as to
make it similar to.day-light ; and, of course, restored to pink j its,
proper colour by day, namely, light blue. This was an impor-

tant observation. At the same time that it exhibited the effect
of a transparent coloured medium in the modification of colours,
it seemed to indicate the analogy of solar light to that result-
ing from combustion; and that the former is modified by the
transparent blue atmosphere, as the latter is by the transpa-
rent blue liquid. Now the effect of a transparent coloured

I

9. In all points where we differ from other persons, the pad

Mr Dalton on the Vision of Colours. 97

medium, as Mr Delaval has proved, is to transmit) more, and
consequently imbibe fewer of the rays of its own colour, than
‘of those of other colours. Reflecting upon these facts, TI was
led to conjecture that one of the humours of my eye must be
a transparent, but coloured, medium, so constituted.as_ to ab-
sorb red and green rays principally, because I obtain no pro-
per ideas of these in the solar spectrum ; and to transmit blue
and other colours more perfectly. What seemed to make
against this opinion, however, was, that I thought red bodies,
such as vermilion, should appear black to me, which was con-
trary to fact. How this difficulty was obviated will be under-
stood from what follows.

Newton has sufficiently ascertained, that opaque baddies are
of a particular colour from their reflecting the rays of light of
that colour more copiously than those of the other colours ; the
unreflected rays being absorbed by the bodies. Adopting this
fact, we are insensibly led to conclude, that the more.rays of
any. one colour a body reflects, and the fewer of every other
colour, the more perfect will be the colour. This conclusion,
however, is certainly erroneous. Splendid coloured bodies re-
flect light of every colour copiously; but that of their own
most so. Accordingly we find, that bodies of all colours,
when placed in homogeneal light of any colour, appear of that
particular colour... Hence a body that is red may appear of
any other colour to an eye that does not transmit red, accord-
ing as those other colours are more copiously reflected from
the body, or transmitted through the humours of the eye.
It appears, therefore, almost beyond a doubt, that one of the
humours of my eye, and of the eyes of my fellows, is a colour-
ed medium, probably some modification of blue. I suppose it
must be the vitreous fhumonr: ; otherwise I apprehend it might
be discovered by inspection, which has not been done. It is
the province of physiologists to explain in what manner the
humours of the eye may be coloured, and to them I shall leave
it; aud proceed to show that the hypothesis will explain the
facts stated in the conclusion of the second. part.

1. This needs no further illustration.

2. Pink is known to be a mixture of red and blue; that is,
‘these two colours are reflected in excess. Our eyes only trans-

NEW SERIES, VOL. Vv. NO. I, JULY 18381. G

98 Mr Dalton on the Vision of Colours.

mit the blue excess, which causes it to appear blue; a few red
rays pervading the eye may serve to give the colour that fad-

~ed appearance. In candle-light, red and orange, or some other
of the higher colours, are known to abound more proportion-
ably than in day-light. The orange light reflected may there-
fore exceed the blue, and the compound colour consist of red
and orange. Now, the red being most copiously reflected,
the colour will be recognized by a common eye under this
small modification ; but the red not appearing to us, we see
chiefly the orange excess; it is consequently to us not a modi-
fication but a new colour.

3. By a similar method of reasoning, crimson, being com-
pounded of red and dark blue, must assume the appearances
I have described.

4. Bodies that are red and scarlet probably reflect orange
and yellow in greatest plenty, next after red. The orange and
yellow, mixed with a few red rays, will give us our idea of red,
which is heightened by candle-light, because the orange is then
more abundant. |

5. Grass-green is probably compounded of green, yellow, and
orange, with more or less blue. Our idea of it will then be
obtained principally from the yellow and orange mixed with ; a
few green rays. It appears, therefore, that red and green to
us will be nearly alike. I do not, however, understand, why
the greens should assume a bluish appearance to us and to
every body else, by candle-light, when it: should seem that
candle-light is defictent in blue.

6. The green rays not being perceived by us, the remaining

rays-may, for aught that is known, compound a muddy red.

{. The observations upon the phenomena of pink and crim-
son will explain this fact.

8. Suppose a body to reflect red rays as the number 8,
orange rays as the number 6, and blue as 5; and another body
red 8, orange 6, and blue 6: then it is evident that acommon —
eye, attending principally to the red, would see little difference
in those colours; but we, who form our ideas of the colours
from the orange and blue, should perceive the latter to be bluer
than the former. ,

9. From the whole of this paper it is evident, that our eyes

3

Dr Seebeck on the refractive powers, Sc. 99

admit blue rays in greater proportion than those of other peo-
ple; therefore, when any kind of light i is less abundant in blue,
as is the case with candle-light compared. to day-light, our eyes
serve in some degree to temper that light, so as to reduce it —
nearly to the common standard. This seems to be the reason
why colours appear to us by candle-light, almost as they do to
others by daylight.

T shall conclude this paper by obperying, that it appears to
me extremely probable, that the sun’s light and. candle-light,
or that which we commonly obtain from combustion, are ori-
ginally constituted alike; and that the earth’s atmosphere is
properly a blue fluid, and modifies the sun’s light so as to oc-
casion the commonly perceived difference.

Art. XI.—On the relation between the Refractive Powers and

the polarizing angles of singly refractive substances.. By
Dr A. Szezecx. Translated from Poggendorff’s Annalen,
1830, No. 9, p. 27.

WaeEn Malus discovered that a ray of light reflected from the
surface of bodies not metallic, possessed the property of being
polarized like one of the pencils formed by calcareous ‘spar,
he sought in vain to discover a relation between the angles at
which this property was most completely produced and the
other properties of the reflecting body. He observed that the
angle of maximum polarization was in general greater with
bodies of a great refraction, and that the pencil reflected from
both surfaces was simultaneously polarized ; but notwithstand-
ing these observations, he expressly says, “ I have determined
with many substances the angle at which light is completely
polarized, and I have found that this angle follows neither the
order of the refractive powers nor that of the dispersive forces. .
It is a property of bodies independent of the other modes of
action which they exercise upon light.”

It must, therefore, have been a matter of great surprise when
Dr Brewster announced in the Philosophical Transactions for
1815, as the results of his measurements, that the angle of
maximum polarization is a function of the refractive power of
the reflecting body. This law he expresses thus :

.
100 Dr Seebeck on the polarizing angles
The index of refraction is the tangent of the angle of pola.

rization ; or according to his other mode of expressing it.
When the polarization is complete, the reflected ray forms a
right angle with the reflected ray. Dr Brewster arranges his
measurements in a table which contains the following eighteen
substances, viz. air, water, fluor-spar, obsidian, bird-lime, sul-
phate of lime, rock crystal, opal coloured glass, topaz, mother-
of-pearl, Iceland-spar, orange coloured glass, spinelle ruby,
zircon, glass of antimony, sulphur, diamond, chromate of lead. —
By comparing the observed with the calculated angles of po-
larization, he found that the difference varied from + 25’ to |
— 32’, the sum of the eighteen positive differences being 85/
and that of the negative ones 174/, which does not seem incon-
siderable when we consider that the observed property is the
mean of a number of observations.
These differences are, nevertheless, not to be ascribed to ac-
cidental mistakes of observation, for the table contains six or
seven doubly refracting bodies; and Dr Brewster has himself
shown in a later memoir in the Philosophical Transactions for
1819, that in this class of bodies the angle of polarization va-
ries with the inclination of the reflecting surface to the axis of
the crystal. These variations, indeed, are so considerable, that
they explain the cause of many more glaring differences: than
those in the table referred to.
With respect to a particular class of singly refracting sub- —
stances, viz. the glasses, Dr Brewster found very considerable
deviations from the law of the tangents; but he regards them
as only apparent exceptions, as he found that they were ow-
ing to chemical alterations on the surface, which changed the re-
fractive power of the surface without changing that of the re-
maining mass, so that the angle of polarization observed on the
surface cannot correspond to the refractive power of the mass.
It is evident, therefore, that in such cases the angle of po-—
larization should be measured on newly polished surfaces of
glass ; but Dr Brewster does not say that he has made any ex-
periments of this kind.
Under these circumstances, it did not seem to me superflu-
ous to resume the inquiry, limiting it to singly refracting sub-
stances, and directing my attention particularly to the surfaces °

of singly refracting substances. 101

of glass, with the view of reconciling Dr Brewster’s law to this
class of bodies, by accurate measurements of the refractive
power and of the angle of polarization in the same pieces.

(Dr Seebeck then proceeds to describe the divided instru-
ment by which he measured the angles of refraction, from
which he deduced the following measures of the refractive

power.)

Colourless fluor-spar, - 1.4341 Index of refraction.
Greenish blue fluor-spar, 1.4343
Common opal, - - 1.4516

Glass A colourless Eng. plate glass, 1.5130
B colourless plate glass, 1.5266
—— C English crown glass, 1.5321

—D do. do. . 1.5523
— E English flint-glass, 1.5783
— F do. do. 1.6206
Pyrope, " 1.8131
Yellow blende, . 2.3692

After describing the instrument for measuring the angle of
polarization upon these substances, which does not differ much
from those previously used for the same purpose, Dr Seebeck
gives the following table of his results. The surfaces were
mostly polished about six and eight months before, and the re-
flecting surfaceson which the polarizing angle wasmeasured were
those by which the ray was refracted when the refractive power
of the substance was determined. The differences between the |
observed andthe calculated angles seldom amount to above
20’, and in very few to above 30’. ‘The calculated angle of
polarization given in the table is that deduced from Dr Brew-
ster’s law.

; Differences.
1. Colourless flwor-spar.
Calculated angle of polarization 4 G59 7
Observed do. on | surface ‘ 55 9 a OP..2
on 2 do. ao > 2566 —0O° 1
2. Blush fluor-spar. | eth.
Calculated angle of polarization 557

Observed do. 1 surface 3 55 14 a7

102 Dr Seebeck on the polarizing angles

Observed angle, 2 surface t
3. Common opal.

Calculated angle of polarization

Observed do. on 1 surface

2 do. -

4. Glass A.
Calculated angle of polarization
Observed do. 1 surface -
2 do. i

5. Glass B.
Calculated angle of polarization
Observed do. 1 surface -
2 do. -

6. Glass C.
Calculated angle of polarization,
Observed do. on 1 surface, ;
2 do. s
3 do. :

7. Glass D.
Calculated angle of polarization, -
Observed do. on 1 surface,
— 2 do. -

8. Glass E.
Calculated angle of polarization,
Observed do. on 1 surface, 3
—— 2 do. ‘
9. Glass F.
Calculated angle of polarization,
Observed do. on 1 surface, -
2 do. -
3 do. -

10. Pyrope.
Calculated angle of polarization,
Observed do. on 1 surface, “
2 do. ;
Ll. Yellow Blende. |
_ Calculated angle of polarization,

— Observed do. on natural surface,
artificial do. ay:

55 9

55 26 ’

55 39

55 41.

56 32

$6.32

56 46

56 96
56 37
56 36

56 52
57 6
57 3
57 14

57 18
57 19
57 20

57 38
57 15
55 (~O

58 19
58 12
58 17
58 8

61 8.

60 28
60. 42

67.7
66 46.

66 35

of singly refracting substances. 103

In ‘most ‘of these cases, the differences are too great to be
ascribed to accidental errors of observation, and it was not pro-
bable that they arose from Dr Brewster’s law being inexact,
or susceptible of modification, because the differences were in
some cases greater in two surfaces of the same body than
might be expected from accidental errors. I therefore deter-
mined to repeat the measurements on a newly ground and po-
lished surface of the glass E, where the differences were great-
est, viz. 23’ and 38’. The observed angle of polarization, by
a mean of twenty observations, was now 57° 40.6, differing
only — 2/.1 from 57° 38’.5, the calculated angle. I now ground
and re-polished the surface of the same prism which had be-
fore given a difference of — $8/, and found it to be, 57° 41’-4,
the difference being only + 0° 2.9

As these small diffiveness are clearly within the limits of ac-
eidental errors of observation, I re-ground and polished all
the other substances in the preceding table, and having re-
measured the angle of polarization, I found it to agree so per-
fectly with Dr Brewster’s law, that the slight deviations from
it could be ascribed only to errors of observation. The re-
sults of these measurements are given in the following table.

The angle of polarization for the glass E, is the mean of
the two measurements already mentioned. The angle for
pyrope is the mean of twenty measurements upon one newly
ground face, which was 61° 3’.3, and of twenty measurements
upon another newly ground face, which was 61° 4’.8. The
angle for blende was observed in two natural cleavage planes ;
the mean of twenty observations in one being 67° 8’.2, and of
twenty in the other, 67° 8.1. The angle for the other sub-
stances was the mean of twenty observations upon surfaces

newly ground and polished.

Colourless Fluor

spar, 55° 6.7 Calc. 55° 6.7 Obs. 0° 0.0 Diff.
Bluish Fluor spar 55 7.0 55 38 —03.2
Common opal, 55 26.3 55 29.3 +0 3.0
Glass A, 56 32 2 56 36.00 403.8
B, 56 46.4 56 45.5 '—00.9
———= C, 56 52.0 56 50.2 — 1.8
peenim' I), 57 12.6 00.0

57 12.6

104 Dr Seebeck on the polarizing angles, &c-

Glass ‘Eis, 60) B7188.6 57 41.0. 402.5 -
ml, 58.19 4000.).68-16.6 402 Bilin.

Pyrope, 61 7.7. 61.40 —0 3.7 h

Yellow blende, .67 7.0 67 8.2 °+01.2

The great agreement between the calculated and observed
results, as given in this table, confirms, in the case of singly
refracting substances, the accuracy of Dr Brewster's law, that
the tangent of the angle of polarization is the index of refrae-
tion,—a law with sibach observation will coincide only when
the heh, al surface has the same property as the rest of the
mass.

What the cause is which produces the ihe upon the
outer surface of the glass has not been determined by my ex-
periments. That there is a chemical alteration produced by
' the air only, particularly on the surfaces of glass, is highly
probable, yet I do not maintain that this is the principal cause
of the observed anomalies. Upon newly polished. surfaces of
the glass C, where the difference was at first — 0° 1’.8, I found
the mean of twenty measurements of the polarizing angle-to
be after sia weeks 56° 54°.6; after fourteen weeks, 56° 5148;
after six months, 56° 54’.0, the differences + 0° 2’.6, — 0° 0.2
and + 0° 2.0 being within the limits of errors of observation,
so that the upper surface does not seem to have suffered any
change in that period. When T had the surfaces of the glass
E, which formerly gave angles which agreed with the calcula-
tion, again polished by an artist, they gave an angle of 58° '7’.0,

which gave a difference of 4+ 0° 28'.5, whereas the differences |

were originally — 0° 23’, and — 0°38’. Hence it can scarcely
be doubted, that this great variation arose from some mechani-
cal cause, produced perhaps by the cleaning of the surface;
and it is probable, that the same cause produced the other
deviations from Dr Brewster’s law. . |

OBSERVATIONS BY THE EDITOR.

The preceding observations of Dr Seebeck are undoubtedly
the most accurate that have been made on the polarizing angles
of particular surfaces, and are exceedingly valuable even as in-
sulated facts, independent of their confirmation of the law of
the tangents. This law, however, had been established by
many observations of my own, subsequent to the publication

Mr Stewart’s Mcteorological Observations, §c. 105

of my paper in 1815, and also by observations of MM. Arago
and Biot ; and it has been adopted by Fresnel as a law rigor-
ously physical, and enters into the beautiful formule with which
he has enriched the science of optics. It derived also additional
support from the numerous observations made by M. Arago
and myself, on the change in the plane of polarization produ-
ced by reflexion.

The results of Dr Seebeck respecting the cause of the super-
ficial changes in glass and other bodies, are, as he allows, not
perfectly satisfactory. . I had shown in my first paper, (Phil.
Trans. 1815, p. 124, 125,) that the anomalies in glass arose
from a chemical change in the surface, which was sometimes
obvious even to the eye, and from oxidations produced by the
action of the air, and by heat. In a subsequent paper on a
different class of phenomena, (See Phil. Trans. 1829, and
this Journal, No. ii. N. Series, p. 209, &c.) I have shown how
to detect these oxidations when they are wholly invisible to
the eye; and I have proved that they take place on some kinds
of glass, and not on others. It would be desirable, therefore,
that Dr Seebeck should repeat his experiments with the glass
E, and examine the state of its surface when it gives different
angles of polarization, by examining the pencil reflected from
these surfaces, when they are covered by an oil of the same
refractive and dispersive power. A slight absorption of some
of the minutely divided matter, used in grinding and polish-
ing the surface, may account for the anomalies in question in

those cases, if any really exist, where they are not produced
by oxidation.

Ant. XII.—Abstract of Meteorological Observations made
in the Isle of Man from 1822 to 1831. By Rosrrt Stew-
“xt, Esq. Receiver-General of the Isle of Man. Commu- .
nicated by Dr H1sBerv.

Iw Number X. of this Journal, p- 281, we have already given
an abstract of Mr Stewart’s valuable observations made from
1822 till 1826. The thermometer was situated in a northern
exposure, and was observed at 9 o’clock a.m. and 11 o'clock
rp. M. ‘The following are the observations made since 1825.

106

: ae

Mr Stewart’s MeteoPological Observations
1826.
Thermometer. Wind.
Number of days.
. A. M. P. M. N. S. E. w.
January, 39 35} 7 1] 8 G'.
February, 44% 43 4 13 1 10
March, 43 442 6 5 14 6.
April, 48 43 11 AR eae
May, 531 50 6 ‘2 ag 4
June, 60 55 11 9 7 Br
July, 664 63 6 11 4 10
August, 67}. 623 1 1k 1 18
September, 58} 53 4d Bae ae
October, 555 4Qt 8 5 4 14
November, 435 42 10 0 tii 9
December, 445 44 8 7 4 12
Gen. Medium, 53} - 494 82 86 87 110
A. M. P. Ms
Highest state of thermometer, - 75 70
Lowest, . " - - - 30 24
Mean, n - . 517°
Weather and Rain.
Number of Days. Inches of
Rain. Snow. Fair. rain.
January, - 7% 1 23 0.79
February, - 17 2 9 4.75
March, - 6 3 22 1.79
April, oe) £40 1 19 2.59
May, - Bom 28: 0.52
June, - 3 0 27 , 0. 4
July, - 10 0 2] 1.30 ©
August, - 14 anil | 2.35
September, 11 0 19 2. 4
October, - 17 0 14 3.55
November, - 11 4 15 3.52
December, - 17 1 13 6.28
Gen. Medium, 126 12 227 29.52

—

Se ee ee

eee.

made in the Isle of Man.

1827.

Thermometer.

A. M. P. M. N.
January, - 39 38) 12
February, - 39 37 9
March, - 42 41 9
April, - 47 45 5
May, - "> 62 49 4
June, - 57 53 8
July, - 60 55 11
August, - 58 55 11
September, - 59 55 5
October, - 54 52 8
November, - 48 48 16
December, - 46 45 7
Gen. Medium, 50 48 105

Highest state of thermometer,

Lowest, : a :

Mean, - pe 3

Weather and Rain.
Number of days.

Rain. Snow. Fair.
January, - 13 5 13
February, - 5 1 22
March, - 15 5 11
April, - S. 0B. 119
May, “ 14 0 17
June, ae 0 19
July, - 10 0 21
August, - I1 0 20
September, - 12 0O 18
October, - 15 0 16
November, - 16 1 13
December, - 21 1 9
Gen.Medium,152 15 198

107
Wind.
Number of days.
Ss. E. w.
4 7 8
4 14 1
2 2) 38
5. 18iKed
17 7 3
12 6 4:
8 8 4
6 12 2
13 10 8
11 12 0
6 5 3
6 Gro lB
93 102 65
A.M. P.M.
70 64:
25 25
49°
Inches of
rain.
4.58
2.12
5.65
2.41
1.76
2.79
2.65
4.58
2.12
3.50
4.33
6.92
AB.AL

108 Mr Stewart’s Meteorblogical Observations

1828.
' Thermometer. - Wind |
. Number of days.
A. M. P. Me N. Ss. E. w.
January, - 43 42 6 &8-. le a
February, - 41 © 42 ot SR Oe 4
March, - 41 43 14 5 6 6
April, - 47 44 6 1l . Sarees
May, - 1564 51 . 3 § - 37 .+6me
June, « Ri5S 55 2 10 8 10
July,» - | 58 | 59 0 0018 -' 3 Ue
August, - 61 58 4 8... i 8
September, - 59 56 2 612 (hoe
October, - 53 51 | 6 210-2 S
November, - 50 48 8 4 Il 7
December, - 49 48 8 10 4 9
Gen. Medium, 51 49 64 113 107 +82
A. M P. M. |
Highest state of thermometer, - 67 64
Lowest, - “ “ 33 82 |
Mean, - - - 502 39
Weather and Rain,
Number of days. Inches of
Rain. Snow. Fair. rain.
January, - Ill 2 18 3.47
February, - 13 2 14 6.2.56
March, ei: 3 21 1.80
April, afi,' ae lL 4 4.38
May, - 10 0 21 25
June, ot a 0 20 1 63
July, - 12 0 19 3.33
Avignst; + 9 G20 6% 2.9
September, - 10 0 20 2.50
October, - 14 O° “O17 , 281
November, - 17 1 12 | 4.72
December, - 19 0 12 5.6
Gen. Medium, 147 ..9 210 ... 85.90

made in the Isle of Man.

1829.

Thermometer.

A. M. Pp. M Ne
January, - 36 41 12
February, - 43 43 6
March, - 41 40 3
April, - 46 42 6
May, - 53 50 4
June, : 60 54 8
July, : 60 55 9
August, - 57 54 18
September, - 52 49 13
October, - 49 47 tag
November, - 44 45 6
December, - 40 39 5
Gen. Medium, 48 46 102

Highest state of thermometer,

‘Lowest, - - -

Mean, ‘ i
Weather and Rain.

Number of days.

Rain. Snow. Fair.
January, - 4 q 20
February, - 9 1 18
March, Le 0 27
April, «DS 2 13
May, 5 0 26
June, a 11 0 19
July, - 18 0 13
August, - 17 , 0 14
September, - 17 0 13
October, - 15 0 16
November, - 14 1 15
December, - 6 2 23
13. 217

Gen. Medium, 135

109

- Wind.

Number of days.
Se E. w.
2 17° 0
2-3
6 @ 0
eee 5
15 7 5
8 6 8
15 4. 3
3 3 rc
8 2 7.
6 7 6
gers 12
14 |g lads bats |
91 110 62

bo Me. Be Ms

-' 65 62

28 27

47°

Inches of

rain.

0.87

158

1. O

3.10

1.53

1.77

2.86

5.80

3.65

6.10

3.81

1.82

33.89

110 Mr Stewart's Meteorological Observations, &c.

August, - 58 52
September, - 54 52
October, - 652 49

1830.
- Thermometer. Wind.
Number of days.
A.M. Pe Me N. i...)
January, - 3893 87 1 1. 28
February, - 38 37 ll 5 7
March, - 445 47 7 6. 13
April, - AT 45 8 Metin *
May, - 52 49 ll sg 5
June, - 55 53 10 oe
July, - 56 57 15 4 7
3
3
2
1

a
—

—
| SD Or D W BD Or =F © SP GO A
~3

November, - 49 45 7 7
December, - 39 38 7 7 1
Gen. Medium, 48.8 46.9 83 104 84 94
A. M. P.M.
Highest state of thermometer, - 66 67 —
Lowest, ‘ a - 25 26
Mean, - - - 47°.8
Weather and Rain.
Number of days. Inches of
Rain. Snow. Fair. rain.
January, - 5 4 22 0.73
February, - 8 7 13 7 2.40
March, - 12 0 19 1.95
April, - 14 2 14 3.72
May, - 19 0 12 3.94
June, ~ hae 0 § 3 2.67 .
July, Sees 0 14 3.61
August, - 12 0 ae 2.67
September, - 17 0 13 — 6.83
October, - 15 0 16 3.42
November, - 14 0 16 3.74
December, - 12 2 17 _ . me!
Gen. Medium, 167 15 183 38.55

Mr Cruckshanks’s Excursion from Lima to Pasco. V1

From these and the former observations of Mr Stewart, we
obtain the following results : | 7
1822, - - hve 51.5

1823, ~ - - 46.1
1824, - - - 49.8
1825, = - - 50.7
1826, - - - 51.3
1827, - - 49
1828, - - - 50
1829, : os - 47
1830, - - - 47.8
Mean Temp. for 9 years, - - 49.24
Correction in consequence of 9", and 11%, not being the
hours of Mean Temperature, - - —0.84
48.40
Mean Temperature according to Dr Brewster's for- .
mula, - - - " —47.58
Difference between the formula and observation, . + 0.82 .

It is curious to remark, that the mean temperature of the
four years, 1822-1825, inclusive, is precisely the same as that
of the nine years, 1822-1830, inclusive.

Art. XITI.—Account of an Excursion from Lima to Pasco.
In a Letter from ALEXANDER CrucksHanks, Esq. to Dr
Hooker.

Turs interesting letter, of which we propose to present an
abridgement to our readers, is published in Dr Hooker’s Botani-
cal Miscellany, (Parts v. vi. p. 177-198, for March 1831,)
a valuable and instructive work, the botanical details of which
are relieved and enlivened by much amusing personal narrative.
We must refer the botanical reader to the original letter for the -
details, in which he will take the greatest interest.

‘** Having determined to accompany my friend Mr M ,
an English merchant of Lima, who had been appointed Director
of a Company for draining the mines, we left the capital at noon
on the 21st of June. Our party consisted of six individuals, and

112. Mr Cruckshanks’s Ewcursion from. Lima to: Pasco.

we had with us three English workmen belonging to the Com-
pany, a servant, and three muleteers: eight laden mules com-
pleted the cavalcade. |
‘¢ On leaving Lima, the road proceeds for about a league to-
wards the coast, to a place called Arnipuquio, and then, round-
ing the hills that separate the two vallies, enters that of Chillon
and turns inland. The Scotch-misty weather, the winter of the
coast, had lately set in, and the hills were beginning to show the
effects of the moisture, being thinly clad with verdure wherever _
a covering of soil had accumulated on the rock.. About half a —
league out of Lima in this direction, there is a little valley bound- ,
ed by: very high hills, called Los Amancaes, from the vast num-
ber of these flowers that appear there at the beginning of winter-
The great height of the hills encourages a plentiful deposition of
moisture, which produces a more abundant vegetation than is
usually seen on the coast. After the rains have ceased in the
interior, the Indians who rear cattle there are accustomed to drive
them down to different parts of the hills and vallies in the low
country, till they reach the coast ; and at this season, a consider-
able number of small flocks and herds are brought to feed at
Los Amancaes. During their stay, the place presents the ap-
pearance of a fair, from the number of people who go out to pic-
nic, and spend the day in roaming among the hills and decking
themselves with the flowers, or in dancing, horse-racing, and other |
sports. This annual promenade commences on St John’s day,
the Amancaes being then in full flower ; and from an early hour,
a great part of the motley population of Lima are seen swarming
towards the hills, gaily dressed in all sorts of colours, of brighter
hue, but not more varied in their tints than the complexions of
the wearers. When the day is fine and the mist confined to the
hills, the scene is singularly picturesque. On one hand, the
steep rocky sides of the valley are studded with cattle tended by
their Indian owners, and gradually disappearing in the mist as
they wind ‘among the hills, the plain below, extending to the
main valley of the Rimac, is covered with groupes engaged in
various sports, and fresh parties constantly arriving; while, on
the opposite side of the river, with distant mountains for a back-
ground, the white spires of the city are seen through the groves
of orange-trees in the gardens of the suburbs ; and lower down,

Mr Gruckshanks’s Excursion from Lima to Pasco. 113

* the cultivated valley leads the eye to the’ ocean, with the Island
of San Lorenzo rising abruptly in the distance.

_ The season was considered late, and the cloudy weather had
not extended far inland, so that, after proceeding a few leagues,
the hills were perfectly naked, and exhibited a marked contrast
to the fields of maize and lucerne in the valley below. We ar-
rived before sunset at an estate called Punchanea, five leagues
from Lima. ‘The proprietor, an old Spaniard, to whom one of
my companions had rendered some essential services during the
revolution, gave us a hearty welcome, and an excellent supper
was prepared for us without garlic. As a compliment to our
English tastes, too, the supper was no sooner removed than ¢ea
was placed on the table.

-. § Providing beds, especially to a party, forms no part of the
hospitality shown to travellers in South America. Each person,
if he have a luggage mule, carries bedding with him, but at all
events, he has some rugs and.a blanket over his saddle, which,
with his: poncho, answer the purpose exceedingly well after sit-
ting all day on a mule. We were, therefore, of course, provided.
with furniture for an immense empty apartment, into which
we were conducted, and which was to serve us for a dormitory.
In Chili, most people on a journey prefer sleeping in the open
air. ‘Those who have never tasted the luxury of passing the
night beneath the bright starry sky of a climate like that of
Chili, cannot form an idea of the sound and refreshing sleep the
traveller enjoys there, nor of the elasticity of spirits, and perfect

freedom from fatigue, with which he springs from his grassy
couch, when the muleteer warns him that the day is beginning to
dawn, and the mules await him to pursue his joummey. But in
Peru, especially in the vallies near the coast, where the climate
is ‘ fair and false,’ it is usual to sleep under coyer: the traveller, -
who, unaccustomed to the climate, should venture to pass the
night in the open air, would most likely awake with an ague, and
very frequently, his only alternative is to immure himself for the
night amidst the smoke and filth of an Indian hut. |
June 22d.—We could not start till eight o'clock, having to
wait for a fat sheep our host had ordered to be killed for us. The:
carcase being duly packed in its own skin, and placed between’
NEW SERIES, VOL. Vv, NO. 1. sULY 1831. HO

114 Mr Cruckshanks’s Ewcursion from Lima to Pasco. '

two trunks on a mule, we set out, accompanied by our hospitable —

friend, who rode with us to the boundary of his estate, where he
left us to pursue our journey. The road continued to wind
round the foot of the hills on the south side of the valley, to the
estate of Cavallero, where there is a post-house, generally made
the first stage from Lima, from which it is distant six leagues.
Near this place there is a bend in the valley, and in order to
avoid the detour, it is usual to proceed up a ravine among the
hills, from whence the road falls again into the valley, several
leagues farther up. The ravine is called Rio Seco, (dry river,)

and dry enough it certainly is, for not a drop of moisture is seen
for a distance of five leagues, although there are unquestionable -

marks of its having been, at some former period, the bed of a
considerable stream. This Rio Seco presents a very fair speci-

men of Peruvian barrenness, of which it is hardly possible to’ |

form an idea without witnessing it. I have already alluded to

the desert appearance of the coast, where you may travel whole

days, over pure sand, without any trace of vegetation ; or, if the
road lies occasionally near a range of mountains, the scene is:
only varied by masses of bare rock, of which the fragments that
cover the road are as fresh and unsoiled as if they had fallen but
yesterday from the hammer of a mason.

** As the day advanced, we found the heat excessive, having
now exchanged the hazy atmosphere of the coast for the clear
deep blue sky of a tropical mountain region. At the head of the
Rio Seco, the road winds up a steep hill, from the summit of
which, the green valley is seen at a distance of two leagues, tan-

talizing the thirsty traveller during the two hours that his mule

takes to crawl over the rough stany bottom of the ravine that
leads to it. |

We regained the main valley about three o'clock, at a place :
called Yangas, consisting only of half a dozen houses, immedi-

ately beyond which is the village of Alcocota, five leagues from.
Cavallero, by the road we came; by the valley it is six leagues
and ahalf. ‘The valley, where we turned off, is nearly a league
in breadth, but here it had contracted to about a mile, and the
hills that bound it are high and steep, especially on the, north
side, where the rock forms a perpendicular wall.

** Alcocota is considered ~ boundary of the rainy district,

Mr Cruckshanks’s Excursion from Lima to Paseo. 115 -

but the showers are only experienced occasionally ; a few leagues
higher up, they fall constantly during the mountain winter.

«< At the end of two leagues, we came to Santa Rosa de Quive,
a small place consisting now only of a few huts on the hill-side ;
a church and some houses in the valley having been destroyed
by fire during the revolution. Here we halted for the night.
The little hut where we stopped was not large enough to con-
tain one-third of our party ; but being on an eminence far above
the valley, there was no danger in sleeping out of doors, and we
therefore took up our quarters in an open shed.

“ June 23d.—Having been fortunate in escaping the attacks.
‘of mosquitoes, which are numerous in the valley, we rose at day-

break, and started as soon as our numerous beasts could be laden
and saddled.

‘¢ Though seated on a natural platform, far above the valley,
the inhabitants of Yazo are very subject to intermittent fever, and
the place has a bad name, on that account, among those who tra-
vel to Pasco; but there can be no doubt that the people bring
the germ of the disease from below. They work all day in small
pieces of irrigated land in the narrow valley, where the heat is
increased by the reverberation of the sun’s rays from the steep
rocky mountains, which, at the same time, prevent a free circu-
lation of air ; and, from the clearness of the sky, they are exposed
after sunset to a sudden chill, while surrounded by a moist stag-
nant atmosphere in this confined situation. I was obliged to put
up here on my return, and, although I had just recovered from
a severe attack of the fever, I found no bad effects from sleeping
in an open shed. .

* The hills near Y azo are very steep, and the road occasionally
very narrow, especially in one part, where it forms a mere ledge
on the side of a nearly perpendicular hill. A pass of this sort
is called a Jadera.. The bank above, consisting of large rolled
stones imbedded in gravel, bore evidence of the heavy rains in
winter, being ploughed into numerous channels, and at that sea-
son it must be dangerous to pass. From some of the loose earth
giving way during the earthquake in 1828, a man and several
mules were precipitated into the valley and killed. .

** At Huarimayo, there was only a single hut, where travel-

116 Mr Cruckshanks’s Kvcursién from Lima to Paseo.

ters usually halt their mules, previous to passing a long and :

elevated Jadera, called the Pacron. This is on the north side
of the stream which we had erossed, lower down, on a very frail
bridge, made of branches of trees laid from bank to bank. 9 5 «

‘On leaving Huarimayo, we continued along the north side of
the valley, which is only wide enough to afford a passage to the
stream. The hills rise so abruptly, that, in cutting a road, it
has been necessary to carry it to a great elevation, following a
natural break in the declivity of the mountain, which allowed
a breadth of a few feet to be levelled between a precipice on the
one hand, and the almost perpendicular wall! of rock that-rises
on the other. The rushing noise of the stream gradually be-

came more faint as we ascended, and died away before we reach-.

ed the greatest elevation, at nearly 400 feet above its bed. The
profound silence that reigns in solitary mountain-districts, where
there are no trees, and we hear neither the song of birds nor the
humming of insects, was only broken at intervals by the shouts
of the muleteers encouraging or threatening their troop, as they
wound slowly in an extended line along the sinuosities of the
mountain. Sometimes, a mule, pressed by a heavy load, showed
a disposition to halt and rest, and consequently stop all those in
his rear, in- places where it was almost impossible to reach him
but in such’cases, a mixed volley of stones and imprecations, with

threats of future punishment, which experience had taught the —

offender not to despise, soon had the effect of putting a
en route.

“Tt chanced that several troops of laden eubias bound to
Pasco, were passing the /adera at the same time, and followed in
our rear. Our muleteers had neglected the usual precaution of
sending forward a messenger to prevent others from ascending in

the opposite direction till we should have descended to the val-

ley and left the road clear; the consequence was, that we were
met at the end of the /adera by another party that had just as-

cended, and our muleteers being in fault, the others insisted that —

we should return; which, however, was out of the question, as
there were a great number of mules behind, in situations where
it was impossible for them to turnround. After much time spent
in altercation, it was agreed that as our opponents had more room

Mr Cruckshanks’s Ewcursion from Lima to-Pusco. 117

to move about in, they should endeavour to drive their mules up
the hill above the road, which was there rather less steep ; this,
with the assistance of our muleteers, was at length accomplished ;
and while we passed down they remained perched in situations
that hardly promised footing for as many goats. ‘There is, per-
haps, more risk in the descent than in the dadera itself, the road
making several sudden turns on the face of the hill, where. it is
cut into steps to prevent the mules from slipping. )

' In this part of the valley, on the south side, a hill rises
abruptly to an elevation of nearly a thousand feet, and from its
summit, a slender stream, like a band of silver, fringed with ver-
dure, winds its way down the steep declivity. At the highest
point, though not seen from the same spot, is a small Indian
village, very difficult of access, whose inhabitants are called in
the Quichua language by the now classic name of ‘ The Chil-
dren of the Mist.’

“ The valley, which had narrowed into a mere ravine, opens
a little on approaching the town of Obrajillo, three leagues from
Huarimayo.

* Obrajillo is twenty-one leagues from Lima, about widiey
between that city and Pasco. Most of the muleteers who pass
between the mines and the capital reside there ; a great conve-
nience to travellers, as they get fresh mules for the remaining
half of the journey. The valley is wide enough to allow some
ground to be cultivated between the town and the stream; and
above the town, towards the south, there is a recess in the moun-
tains, occupied by low rounded hills, which have been levelled
and formed into a series of small terraces for the cultivation of
grain and vegetables, a sort of work for which the ancient Peru-
vians were celebrated. ‘These patches of land being irrigated by
a stream of water brought from above, the tufaceous rock readily
decomposes by the constant moisture, and, combined with vege-
table mould washed down by the rains, forms a black fertile
loam, which yields luxuriant crops without manure. On an emi-
nence at the extremity of this cultivated land, about — feet above
the level of Obrajillo, and half a mile distant, in a straight line,
stands the town of Canta, the chief town of the province of the
same name, and the residence of the Intendant and.a Governor ;
it consists, however, like Obrajillo, of small houses, little better.

118 Mr Cruckshanks’s Excursién from Lima to Paseo.

than huts, and the population of the two towns, chiefly. Indian,
is only about eight hundred souls.

** 'The day after our arrival was the feast of St John, the patron
saint of Obrajillo. Our muleteer being one of the alcaldes of the
town, and named after the saint, his presence was considered
necessary at the festival. It was recollected, too, that the name
of my friend was likewise John, and as the people of the town
are chiefly supported by the traffic occasioned by the mines,
which was expected to be greatly increased by the erection of
the steam engines for draining them, it was argued, that there
could be no hope of patronage from the saint in the undertaking
if we refused to devote a day tohim. <A still more powerful
argument was mentioned incidentally, that, as the fresh mules
were feeding at some distance, they might not arrive sufficiently
early for us to start the following day, even if we wished it,
which meant, as we knew by experience, that the mules certainly
would not arrive, whatever our wishes might be, and we were
therefore obliged to declare our willingness to do honour to the
saint. For my part, I was very well pleased to stay, as the de-

lay gave me time to pack up my seeds, and change the papers ©

of my plants, and to collect a few more in the neighbourhood.
** On the 24th, St John’s day, a great part of the population
of Canta and Obrajillo assembled at the church of the latter to
hear mass. The walls of the building were decorated with
large bouquets and festoons of flowers, and the interior was
lighted up by a great number of candles, mostly furnished by

the poor Indians, who are taught to consider such contributions -
as part of their religious duties. Among other ornaments, we .

were struck by a unique display of small flags, formed of colour-
ed cotton handkerchiefs of different patterns, from the looms of
Manchester and Glasgow, fastened to canes that were stuck into
the walls. There was not room within the church for all those
assembled, and many knelt in the open air before the door,

where they remained till the mass was said; and during the —

whole time, six Indian girls were dancing, and singing in the

Quichua language, in the midst of them. When the unfortu-.

nate aborigines of these countries were first subjugated by the
Spaniards, in order to insure their attendance at the festivals of
the Catholic Church, the priests allowed them to use the songs:

a ee

= ee. eee ee Ee eee

te i et

Mr Cruckshanks's Excursion from Lima to Paseo. 119

and dances they had been accustomed to at their own feasts, and
the custom is continued to the present day. After mass, the
congregation, headed by the priests, marched in procession round
the plaza, and while the latter were chaunting a part of the
church service, the Indian girls continued to dance and sing
round them, accompanied by several men dressed in the ancient
costume of the Incas, some of them having their faces covered
with hideous masks made from calabashes. This performance
was continued even while the priests were officiating at a tem-
porary altar, erected on one side of the plaza. Immediately
after the procession, a cock-fight was exhibited, and the rest of
the day was consumed in eating and drinking. |

‘* 'The next stage, of seven leagues, lies across the Cordillera,
and there is no intermediate place to sleep at.

© A little below Culluay, the valley expands. ‘The alcalde,
at. whose dwelling, being the largest in the place, we intended
to pass the night, was absent, like the rest, in the fields; and
the door being locked, we had to wait patiently for his return.

** Tt was evening when we arrived, and, as the sun went down,
we found the air piercingly cold, so that we were glad to crowd
round the turf fire of a smoky hovel, that. served for a kitchen,
till our host came, and supper was prepared. <A party from
Pasco arrived shortly after us, and informed us that snow had
fallen for several days in some parts of the Cordillera, where
partial snow-storms are occasionally experienced at all seasons,
but it seldom falls till after midday. !

“¢ 27th.—As we had a rough day’s journey before us, we
were obliged to rise before daylight, and several of our party who
had not quitted Lima for some years, did not at all relish the
fresh morning air, at a temperature very little above freezing.

‘‘ Advancing from Culluay, there is a great sameness in the
appearance of the hills, which are mostly covered with a smooth
compact turf. A long dadera conducted us to the head of the
valley, where we crossed a small rill that takes its rise in a
neighbouring ravine, and is the source of the river of which we
had traced the course from the coast. At this spot, called the —
Alto de Jacaybamba, two leagues from Culluay, we commenced
the ascent of the Cordillera. It was steep and rugged, lying
among rocks of porphyry and ¢ufa, like that at Canta. A large

120 Mr Cruckshanks’s Eavcursion from Lima to Pasco.

insulated hill, called La Viuda, several hundred feet above the
road._at the highest part of the pass to which it gives its name,

consists of the latter rock, enclosing large rolled masses of
porphyry.

** On gaining the summit, a league from the bottom of the
mountain, we came upon a more open country than we had seen
since the commencement of our journey, though the prospect was
still somewhat limited, the lowest situation being, of course,
chosen, for the road, from which we only had a partial view of
the higher mountains in the distance, covered with perpetual
snow. We descended very gradually among low ranges of black
limestone, with impressions of shells; a very extensive forma-
tion in this part of the Andes. The skirts of the hills, and the
little vallies and tracts of level ground between them, were
covered with verdure, and the deeper hollows were occupied by
lakes, the water of which was of a dark blue colour, more intense
than that of the waters of the ocean; in some of them, the
deeper tint was varied by patches of bright turquoise, from the
bottom being of a whitish colour, and the water less deep.

‘* The snow that had lately. fallen had already disappeared
from the open ground, but much of it still remained in sheltered
places.

** Before leaving Culluay in the morning, we had been “il
vised not to take any breakfast except a little broth, to lessen the
risk of suffering from the pwna or veta, the sickness that fre-
quently attacks those who are unaccustomed to breathe the rari-
fied atmosphere of these elevated regions. None of the party,
however, had experienced any inconvenience in the ascent ; and
after proceeding about half a league, where the elevation was
considerably less than at the pass, we halted at one of the lakes,
and breakfasted on some cold meat. But we soon found that we
had calculated rather hastily on our exemption from the puna ;
and that, like sea-sickness, which it resembles so much in other
respects, it does not always immediately attack those who are
liable to be affected by it. Before we had advanced half a mile
from the lake, several of. the party began to suffer from head-
ach; and Mr M and myself were so ill that we found
some difficulty in reaching the end of the stage, a place called

Casa-cancha, to which we descended about four o'clock. We
1

Mr Cruckshanks’s Excursion from Lima to Pasco. 121

had ‘scarcely arrived when we were both seized with violent
__ vomiting, accompanied by all the sensations that usually attend

_ sea-sickness, but the throbbing pain of the head was much more
acute and depressing.

It is generally said that difficulty of breathing is one ‘of the
most common and distressing symptoms of this disorder, but it
is not the case. Few people suffer in their respiration, although _
the pulse is frequently accelerated, while they are riding or
walking on a level road; it is only in walking over rough
ground, or in climbing the mountains, that respiration is affect-
ed, and it then becomes necessary to halt repeatedly and take
breath. The miners work as hard, and perform the same quan-
tum of labour at Pasco, fourteen thousand feet above the level
of the sea, as those at a sixth-part of the elevation ; and indeed
the English mechanics there, unless very Jaboriously employed,
performed their work without suffering any convenience from
this cause. Several of our party,.who had frequently been at
Pasco, and resided there a considerable time, were not affected ;
and, indeed, the only one who was attacked besides Mr M-
and myself, recovered almost immediately. In this, too, the
puna resembles sea-sickness, that different individuals, under
precisely similar circumstances, are affected in a very different de- _
gree, and many do not suffer at all. It is, however, worthy of
remark, that the same persons are not equally affected by the
two disorders. My friend and I, some years before, had made
a voyage of four months together, and he only suffered for a few
hours from sea-sickness, while I was never wholly free from it
during the voyage ; but, in the present instance, he suffered more
severely than I did. Persons of full habit, affected with the
puna, frequently spit blood. Some months before we passed, an
Englishman, who had been employed at the mines, set out to
walk to the coast ; he had previously been in bad health, and
shortly after his arrival at Casa-cancha he died, from hemor-
rhage, having burst a blood-vessel in the lungs. |

‘The valley of Casa-cancha is about half a mile wide, idhvatiely
terminated by the limestone hills we had passed over, and bound-
ed at the side by red sandstone and conglomerate. We were
lodged at a miserable hut, built of stones and mud. © The sin-
gle apartment, of which it consisted, served us successively for

122 Mr Cruckshanks’s Excursi6n from Lima to Paseo.

a kitchen, dining-room, and bed-room: the dinner was cooked
over a turf fire, the smoke from which eddied round: the roof,
‘and then partially escaped by the lee which was nite
about four feet high.

“© At daybreak, on the 28th, when we raised the piece of ony
‘cloth that served for a door to our dwelling, the whole valley
was so thickly covered with hoar-frost, that it appeared as if

‘snow had fallen in the night. We were delayed more than two
‘hours from some of our mules haying strayed to the hills. As _
the beasts are suffered to wander about at night in search of pas-
ture, an Indian is generally to be found where travellers halt,
who, for a trifling reward, undertakes to keep them together:
he passes the night in the open air, frequently in the midst.of
frost and snow, and is seldom known to sleep, or neglect his
charge. In this instance, a dense mist had filled the valley, and
no blame could attach to the watchman; but from the abuse
that was lavished upon him, one would have thought that he
had been taken in the act of stealing all our mules, instead of
merely not having seen one or two of them through the miston
a dark night.

“ Mr M continued very ill, and although I felt tolerably
well when I rose, we had not travelled half a league when the —
headach returned with increased violence, and it was greatly |
aggravated by the motion of the mule. Some of our companions,
too, were similarly affected in the course of this day’s ride. ._

_ « The valley, and even the slopes of the hills, were so swampy,
that we travelled very slowly for about a league and a half, when
we left the valley, and crossed over some high land that brought
us to the small river of Palcamayo, three leagues from Casa-
cancha. From Palcamayo, we passed over a succession of low
hills, covered with short grass; the intervening hollows were
very swampy, and we were frequently obliged to make a long
circuit to avoid them. The whole of the district through which
we were travelling, including the plain of Bourbon, whither we —

were bound, and the country for many leagues tothe north and
south, may be considered as forming an immense basin between
two distant Cordilleras ; and from the quantity of rain and snow
that falls in winter, and the thawing of the latter on the sum-
mits of the hills and sides of the mountains during summer, the

Mr Cruckshanks’s Eacursion from Lima to Pasco. 128

‘subsoil in the low grounds is always saturated with moisture,
and numerous springs issue from the surface. On the plains
and slopes of the hills, there is, all the year, an abundance of
grass, which serves to pasture large flocks of sheep for the sup-
ply of the vallies and the towns on the coast.

_* Owing to the badness of the road, our progress had been
so slow that it was long after dark when we arrived at a ravine,
down which we continued to Huayllay, a small Indian town, and
the centre of a mining district, eight leagues from Casa-cancha.
The monotonous appearance of the hills among which we had tra-
velled, at a very slow pace, the intolerable headach we suffered,
and the benumbing cold of the evening wind, made this altoge-
_ ther a fatiguing and unpleasant day’s journey.

*‘ One of our party, a Spaniard, conducted. us to the house |
of the Governor, who was his countryman. He had been a sol-
dier in the Spanish army, but having married an Indian woman
of Huayllay, he settled in the town, where his intelligence and
activity procured him the office of Governor; to which he ad-
‘ded the profession of a miner, and the trade of a shopkeeper.
Our apartment was in keeping with the mixed pursuits of the
master of the house; the table was covered with papers relative
to the number of recruits, and the tribute to be furnished by the
Indians under his jurisdiction; a heap of silver ore occupied a
corner of the mud floor, and candles, sugar, jars of spirits, and
similar merchandise were spread around, with very little regard
to arrangement. Our host and his dark lady vied with each
other in ministering to our wants; and, stretched on the floor
of their domicile, we soon forgot the ‘panae and our tedious ride
from Casa-cancha.

“In the morning, we were again greeted by the glittering
hoar-frost, which added to the desolate and wintry aspect of the
town and surrounding hills, where not a tree nor a trace of cul-
tivation was to be seen. All the corn and vegetables consumed
by the inhabitants are brought up from the vallies, and have to

be carried fifteen or twenty leagues.
© Having arrived at Huayllay at night, we had not perceived
that the valley in which it stands passed through an extensive
formation of irachyte. A small stream runs in the bottom,
from which a steep grassy slope rises on each side, surmounted

124 Mr Cruckshanks’s Ewcursion from Lima to Pasco. '

by a craggy and precipitous wall of the érachyte rocks. Half
a league below the town, we passed some hot springs: the water
leaves a calcareous deposit, which is gradually encroaching vars
one side of the valley.

** At the lower extremity of the valley, the trachyte is divids
ed into columns, coated with blackish Jichen, that from a dis-
tance gives them the appearance of basalt. The masses have
been very differently acted upon by the weather, some parts dis-
integrating more readily than others. Many columns stand
alone ; they are obliquely divided by transverse fissures, and the
different joints have been unequally worn, so that a slender shaft
sometimes supports an immense mass on its summit, and the
whole has the appearance of architectural rai, ee
with grotesque’ colossal figures.

* On emerging from the valley, we found ourselves at last on
the plains of Bourbon, which extend fifteen or twenty leagues
from north to south, presenting a surface of green sward as
level as a bowling-green. We had now only to travel six leagues
to the mines, situated among the hills on the opposite side of
the plain. At the distance of two leagues, we passed a low
belt of limestone, and we crossed three small rivers on our way.
When we looked at the vast meadow over which we were tra+
velling, bounded by gently swelling hills that shut out the view
of the distant snowy peaks, we could hardly persuade ourselves
that we were fourteen thousand feet above the level of the sea.

“© Having reached the further side of the plain, and crossed
a range of limestone rocks, we came abruptly upon the town
and mines of the Cerro de Pasco, which occupy one side of an
open space, about half a league across, and nearly surrounded
by rugged hills. ‘The satisfaction we felt at having arrived at
the end of our journey was increased upon entering a house fit-
ted up by the Pasco Peruvian Company, and finding ourselves
in a comfortable apartment, with boarded floor and glass win-
dows, and a coal fire blazing in an English grate. Mr’ M——
was the only one who continued to suffer from the puna after
our arrival ; he was seriously ill for some days, and confined ys
his room upwards of a week.

“© This celebrated spot, from which so much wealth havi is-
sued, has a wretched appearance ; the town consists of narrow

Mr Cruckshanks’s Excursion from Lima to Pasco. 125

straggling lanes, the houses are small and dark, and the mass
of the people squalid and miserable. Heaps of refuse from the
mines surround the town, which is built immediately over some
of them, and there are many shafts opening into the public
roads without any fence or covering, so that, on a dark night, it
is impossible to pass from one part of the town to another with-
out imminent risk.

“« I was struck here, as at Huayllay, by the eflanmey aspect
of the scene, notwithstanding the sun was shining in the midst
of a bright sky; but I soon perceived that the very clearness
‘of the sky was the cause of this phenomenon. From the per-
fect transparency of the atmosphere, the sun’s rays are unim-
peded, and a dazzling light falls on objects directly exposed to
their influence, while those that are in the shade receive very
little indirect light from the dark blue heavens; and thus, a
striking contrast is produced between the glare of the illuminated
surfaces and the unrelieved shade, very different from the effect
of the diffused light in the hazy atmosphere of the coast. This
gloomy effect is increased by the total absence of trees, and the
general prevalence of sombre hues in the surrounding objects :
the hills of bluish limestone, with the meagre unhealthy vegeta-
tion thinly scattered upon them; the stagnant lakes, buried in
their recesses, and reflecting their darkened images; the decay-
ed thatch of the houses; the grey and brown dresses of the In-
dians, whose dark faces are mottled with purple blotches from
constant exposure to the bleak atmosphere of the Cordillera; all
conspire to increase the sadness of the scene, which looks as if
a neutral tint were passed over the whole landscape. But all
this is amply compensated by the beauty of the nights in fine
weather, especially on the hills above the town, which command
a view of the snowy ranges that surround the plains of Bour-
bon ; the colour of the sky is deep indigo, and the stars shine
with a splendour that can be but faintly conceived by those
who have witnessed their brilliance on a clear frosty night in
Britain.

“ While in Pasco, I received several letters from Dr Pcep-
pig, who crossed the Cordillera about a fortnight before us. He
had suffered severely from the pwna, and continued dangerously
ill during the few days he remained in Pasco, from whence he

126 .. M. Kupffer’s Account of the Russian Steppes, °

passed on through Huanuco, to Pampayaca, the most remote
estate on the river Hualluga. Previous to leaving Chili, this
accomplished and enterprising naturalist had spent eight months
in exploring the interior of the province of Concepcion, and had
examined the Flora of an extensive district in the mountains ad-
jacent to the volcano of Antujo, where no botanist had ever be-

fore penetrated. Dr Pceppig’s Chilian collections are among

the most extensive and valuable ever made in South America.
In Peru, his intention was to examine the productions of the
country bordering on the river Hualluga, and then to endeavour
to descend by that stream to the Amazons, and return by way
of Para to Europe.

*‘ On the 24th of July, I made an excursion for a single day
to Huayllay ; and, on the 28th of August, I set out on my re-
turn to Lima, where I arrived on the 2d of September.”

Art. XIV.—Account of the Russian Steppes, with Geognosti-
cal Observations made in a Journey to the Environs of Mont
Elbrouz, in the Caucasus, undertaken in 1829 by order of
the Emperor of Russia. By M. Kuerrer of the woo:
Academy of Sciences.

‘Towarps the north the chain of Caucasus gradually descends
into the immense Steppe which constitutes the middle of Rus-
sia. From Voronetz to Stavropol we scarcely meet a single
- hill or tree. Houses become more and more rare, and are col-
lected on a small number of points where the action of some
river interrupts the uniformity of the soil, and renders more
fertile the black soil of the steppe, which is sterile by excess
of strength, by diluting it with sand. In passing through these
villages, we are equally surprised with the sight of a few trees,

and sometimes we see in the distance sites crowned with wood. ©
In these countries it would appear that the inequality of the —

soil is a condition necessary to the formation of forests; the
cause of which probably is, that the rocks which have never
been overturned, present too few discontinuities to allow a suf-
ficiently free passage to the waters necessary for the Peer
of a considerable vegetable mass.

with: Geognostical Obervations; $e: -° 127

We also travelled from ‘Taganrog to Nicolaieff, the steppes
which border on the Black Sea and the Sea of Azoff. These
steppes present the same character of uniformity and sterility.
In July, everything is burnt up and yellow by the heat of the
sun, whose rays meet with no obstacle ;—we find ourselves in
the middle of a desert; notwithstanding the rapidity of our
course, (the roads made. by nature are-excellent, and we run
no risk in riding with a loose rein, for we meet with no inequa-
lity, nor a stone nor a ditch,) we scarcely saw within our view
more than a dozen huts of Cossacks, who have established
themselves in the vicinity of some muddy spring to fornish
post-horses for travellers.

_Tn order to form a correct idea of the nature of a steppe, we
must visit it in spring, when the plants which cover it. are not
yet withered, or rather destroyed by the heat of summer. I
had occasion in the spring of 1828 to see the steppes which sur-
round Serguiewsk, in the north of the government of Oren-
bourg, and I shall here describe it as a substitute for that of ©
the steppes of the Black Sea, for which I was unable to collect
the necessary materials, because we visited it when the season
was too far advanced.

Serguiewsk is celebrated in eastern Russia on account of its
sulphureous springs, which attract every year crowds of inva-
lids. This establishment, if we may give this name to thirty
cottages neatly built, and inhabited only in the fine season,
is situated at the confluence of the Sourgout and the Soka,
1}° nearly to the east of Kasan, and in lat. 54°. It is at the
foot of a hill composed of calcareous rock mixed with gypsum,
that the mineral springs rise, containing sulphuretted hydro-
gen and carbonic acid. When we are on the summit of this hill,
we see the land rise insensibly, and terminate by forming an im-
mense plateau, where the eye loses itself in the horizon without
meeting with any elevation. Such a plateau presents the cha-
racter of a true steppe.

The physical character of the steppes consists in 1 great dry-
ness, and in very considerable variations in the temperature of
the air. Their dryness is easily explained by their relative
elevation and by their uniformity of level: It would appear
that a certain inequality in the ground is an indispensable con-

128 —-M. Kupffer’s Account of the Russian’ Steppes,

dition to the formation of springs; ‘and it is this’ inequality,
indeed, which can alone produce the necessary ‘pressure for

causing the water to rise above the surface of the earth. It is’

more difficult to explain the difference between the’ climate of
the steppes and that of unequal ground, but it is a fact which is
well established. ‘The changes of temperature are greater in
the steppes, the winter being colder and the summer warmer.
Russian travellers who have lately visited the steppes which
separate the Sea of Aral from the Caspian have been almost
always exposed toa cold of from —20° to —25° of Reaumur,
(— 18° to — 25° of Fahrenheit,) accompanied with a very
high wind. The north and north-east winds, which blow vios
lently during winter, meeting with no obstacle, carry into the
steppes the climate of the colder regions from which they
come; whilst in summer the south and south-west accamulate
as it were there the heat with which they are charged, and
which is neither absorbed by evaporation nor extinguished by’
any shadow. During the day the atmosphere i is insufferably’
hot; during the night the variation is so strong that a very’
sharp cold is sometimes experienced. ‘These considerable and’
sudden variations of temperature destroy the tender vegetation
of annual plants, and leave only the perennial ones, whose lig-
neous and hardy stalks offer a greater resistance to their in-
fluence. The plants which are numerous are the Robinia fru-
tescens, the Hedysarum grandiflorum, the Astragalus Austria-
cus and sulcatus, the Oxytropis caudata, and pilosa, and other

papilionaceous plants; several species of Artemisia; and the |
Prunus cerasus nana, the cherry tree of the steppes, which —

scarcely reaches a foot in height, and whose sour fruit is é6l-'

lected by the inhabitants. Wherever the steppe is traversed —

by rivers, or where a slight inequality in the ground permits
the water to amass in a greater quantity, the hardy plants soon’
disappear beneath the plough; and the steppe is changed into
a productive soil; trees multiply on the heights, and houses

and villages appear.

It is thus that the banks of the Don, and of the Donati .

(Little Don) and other rivers which flow through the country
of the Cossacks, are peopled. A great number of villages,
some of which are very considerable, stretch along the banks’

Ee

with Geognostical Observations, &c. 129

of the Don; but in receding from the river we find ourselves
in the middle of a steppe and in an inhabited country. The
Don near its embouchure at Tcherkask widens considerably
as it recedes from the hills composed of a chalky calcareous
rock, which present to it on its right bank an insurmountable
barrier ; it inundates every spring a great extent of country,
and spreads over it abundance: From the Axais to the Tcher-
kask, the culture of the vine, fisheries, agriculture, and com-
merce, give employment in their turn to thousands of men,
-who draw from them a certain and an agreeable subsistence.
This is one of the most animated scenes that I have ever seen,
and particularly strikes the imagination of the traveller who
has been travelling over the steppe.

Several -hills which advance towards the Sea of Azoff, on
the right bank of the Don, rise nearly to the height of 500
feet above the level of the Don, and are composed of a calcare-
ous rock filled with fragments of shells, which it would be dif-
ficult to refer to their species. New Tcherkask is built on one
of these hills: This town is asit were placed on a promontory,
which advances from the steppe of which it forms the prolon-
gation towards the Sea of Azoff. Its position partakes in the
dryness and sudden changes of temperature of the adjoining
steppe, without sharing in the advantages which the Don sheds
over its banks. The inhabitants are obliged to collect the rain
water in cisterns, in order that they may be supplied in the
heat of summer. ‘The town has little trade, and its existence
depends chiefly on its being the centre of government, and the
chief place of the Cossack territory. The calcareous rock
which forms the soil has a wide extent. .We meet with it
every where from Stavropol to Nicolaieff, and it forms the
shore of the Black Sea. Sometimes it is filled with broken
shells, and sometimes it 1s formed in beds more or less desti-
‘ tute of organic remains. Though this rock most frequently
presents only a heap of the debris of shells cemented by a cal-
careous paste, we sometimes recognize entire specimens, parti-
cularly the Cytherea, sometimes the Mytilites, and generally
sea shells. This rock is always arranged in horizontal beds.
It is only beyond Stavropol, and in advancing towards the
mountains of the Caucasus, on the road to the hot springs, that

NEW SERIES, VOL. V. No. I. JULY 1831. I

130 = M. Kupffer’s Account of the Russian Steppes,

we see a change in the aspect of this rock and of its contained
fossils: Sometimes it is very compact and of a grey colour,
whereas the rock containing thé Cythere, when devoid of

shells, is always very white, and generally so soft that it is

‘often friable : Sometimes it becomes a little more porous, and
contains some fossils of the family of the Helices. It is with

this limestone rock that the country begins to present an un-—

dulated surface, so that we perceive that the mountains are ap-
proaching. In quitting Stavropol, we descend into a wide

plain, at the extremity of which is situated the village of Na- —

deja, twenty versts from Stavropol. This limestone (which I
shall call the helical limestone, to distinguish it from the
cythereal limestone,) extends to Kalinova ; and it is between
this village and the small town of Alexandrovsk that we ob-
serve on the right, in descending a hill, some insulated rocks
of sandstone, and, at the same time, the snowy top of Elbrouz
(or Chad,) anda part of the central chain of Caucasus presents

itself for the first time.
This sandstone is distinguished by a particular hide ai shell,

with which it is filled, and of which M. Pander (who has

thrice visited the shores of the Black Sea,) has formed the new
genus Hypania. The sandstone is of a yellow colour, it
slightly resists the blow of a hammer, and sometimes becomes
even friable ; it is liable to perpendicular cleavages, and to form
enormous blocks with salient angles, and of a grotesque form ;
_ it effervesces strongly with acids, even at places which contain
no fossils ; and there are grains of sand enveloped in a calea-
reous mass, which is sometimes deposited in separate beds. _

A phenomenon deserving of notice is the great fertility of
this soil. It appears that the sandstone, being more porous
than the calcareous rock, the subterranean waters circulate in
it with more facility, and distribute themselves more uniform.
ly, so that plants whose roots are almost constantly moistened
resist better the burning heat of the sun in the steppes, At
some points the country loses entirely the character of a steppe.
We meet with trees, cultivated fields and lakes,’ habitations
multiply, the means of subsistence increase, whereas. enery-
thing in the steppe languishes.

Behind Alexandrovsk, the view of the chain of the Caucastis

te te i i i et

with Geognostical Observations, &c. 11

is more and more developed: It occupies towards the south
east a great part of the horizon. It commences on the right
with Elbrouz, where two summits rise high above the rest of
the other mountains, and it terminates on the left with Kas-
beck. This chain is more visible, as we advance to near the
mineral springs into a plain whose undulating surface rises
nowhere so high as to intercept the view of the mountains.
We observe, however, even here several insulated cones which
rise in front of the snowy crest, and whose sombre colour may
be distinguished from it. These are Bechtav and the other
trachytic hills which surround the hot sprmgs. At Sablinsky,
and at Gheorgievsk, their aspect becomes more and more im-
posing: In quitting this last town, the capital of the Cossacks
of the line, we enjoy a very agreeable, and at the same time a
very instructive view, for we are struck with the relation be-
tween the forms of these trachytic cones and the central crest
of Caucasus, whilst the chain of mountains which separate them,
and whose height is much greater than that of Bechtav, pre-
sents a series of elevations whose undulating outlines form a
strong contrast with the precipitous rocks of which the central
chain is composed.

Before reaching the hot springs the formations are observ-
ed to change: The mineral waters themselves rise from a
compact calcareous rock: The Mahouca, a mountain 1000
feet above the hot springs, and at the foot of which they have
their origin, is entirely composed of this rock: Fossils are
rarely found in this limestone: Ammonites and Terebratulites
have, however, been discovered. I shall call it the Ammonite
limestone, because this kind of fossil IPN: characte-
rizes it.

The hot springs which abound with artsdbdins of lime have
deposited a particular sediment filled with impressions of
leaves: This deposit is in some places considerably thick. It
covers entirely the foot of Mahouca, and rises here and there
along the flanks of this mountain, where it sometimes forms
small caverns. It is easily distinguished from the limestone
of which the Mahouca consists, because is is deposited in the
manner of sediment in thin and undulated strata. It is some

132 = =M. Kupffer’s Account of the Russian Steppes,

times susceptible of a high pours and — a pend
agreeable delineations.: tae

The most remarkable rock in ie vicinity of the hot spritign
is that which composes the Bechtav. This mountain forms a
mass perfectly insulated, rising rapidly 3000 feet above the
plain, and 4000 above the Black Sea. Its five conical sum-
mits have given it the name of Bechitav, which signifies five
mountains in the Nogay language. The rock of which it
consists is a white trachyte, with small crystals of glassy feld-
spar, some grains of quartz, and small needles of green am-

phibole disseminated through a white paste of compact feld-

spar. The strata of calcareous rock which rest on the foot of
this mountain do not appear to have experienced any -ulterior
change in their primitive position, which proves that they have
been deposited since the eruption of the trachytic masses.

The hot sulphureous springs are several versts distant from
Bechtav ; but we find at it base ferruginous springs, which
are likewise hot or lukewarm. In the vicinity of Bechtay
there exist other mountains which resemble it in their external
form and composition, for example, Verblioud, (Camel,) the
Lissigora, (mountains of foxes,) the Zmeievaia, (mountains of
serpents.) These mountains are insulated, and are not even
placed in the same line. ye

_ In advancing from the hot springs to the chain of Caucasus,
we do not quit the calcareous country till we descend on the
banks of the Malka. We at first see rising on the opposite
bank of the river mountains of a particular form : we find up-
on their declivities immense and angular blocks, which we had
previously found above sandstone with hypanites. ‘The strata
themselves, though horizontal, present a great number of ver-
tical fissures, and the rocks which they compose are very rug-

ged. It isa sandstone characterized by the Ostracites which _

it contains. 'The Malka separates for a long time this: forma-
tion from the calcareous formation of which we have spoken,
In our route from the stone bridge over the Malka at Kin-
jal, we crossed the sandstone country in a direction from
N. to S. It here rises to the height of 5000 or 6000 feet above
the sea, and forms plateaus of considerable extent, intersected
in every direction by crevices and deep grooves, where the

< ial
am — — —<>--., * st

with Geognostical Observations, &c. 133

‘horizontal stratification of this rock appears. Upon this hill,

not far from Mahomet Kourgan, whence we discover the val-
ley of Baksan on the Haimacha, we at last see the sandstone
rise with a calcareous rock on which it rests, and which is the
oldest secondary limestone of the Caucasus. In the valleys of
Kichmalka and of Kassaout we have met with a ‘sandstone,
which, in the series of superpositions, ought to be the same as
the sandstone with ostracites; it is, however, entirely. devoid
of fossils. In the valley of Kassaout, it is very compact at
places on a lower level, where it sometimes. contains strata of
argillaceous schistus. It is very quartzy at the same place,
and does not effervesce with acids, while on the we it is
much mixed with carbonate of lime. ‘

In an excursion in which we went out of the valley of Kies.
saout, in advancing towards the central chains to seek for a
Jead mine which the Tsherkesses had. mentioned. to us, we met
on the heights which we traversed a very coarse conglome-
rate; rounded peebles of common white quartz, grey brown
and black j jaspers, and some fragments of argillaceous oni
are all imbedded in a quartzy cement.

In-spite of the most careful examination, I ebali not find
any fragment of trachyte in this conglomerate.

When we have reached the boundary of this plateau, we are
still separated from the central chain by a wide and deep val-
ley, and it is while descending a little towards this valley that
we suddenly meet with nearly vertical strata of a particular
rock, against which the above-mentioned conglomerate appear-
ed to lean. We soon discover ancient works for obtaining the
particles of sulphuretted lead. disseminated in the rock. In
the parts near the conglomerate this rock is also composed of
pieces of rolled quartz, cemented by a very ferruginous clay, .
(not far from this is found much ochre of yellow iron,) in other
places the relative quantity of the pieces of quartz diminishes,
the paste predominates, and we see it distinctly composed of
two substances, feldspar and sulphate of barytes ; it is also the
sulphate of barytes which forms the gangue of the sulphuret
of lead, and the thin strata of it are traversed by narrow veins
of the compact sulphurets of lead and antimony, grey copper,

a

134 M Kupffer’s Account of ‘the Russian Steppes, '

and oxide of manganese, all of which are so small in quantity
that the works were soon abandoned. eM
It was in our excursion to Kinjal and to the Ourda that I

had occasion to study the secondary formations which were —

older than the sandstone with ostracites. We have already
seen that this sandstone rests immediately on a calcareous rock
in which I have not met with any fossil remains. On the Hai-
macha, where we halted the 10th of July, this limestone,
though generally compact, had small lamelle of carbonate of
lime disseminated through it. The rocks which follow the
banks of the lower Ourda are composed of this calcareous for-
mation, which appears to have a great extent, as we'shall pre-
sently see. I shall call it limestone with gryphites, for I after-
wards met with very large and beautiful specimens of this fos-
sil in a limestone rock which I believe belongs to the same
formation. I have shown in the historical part that the Inal,
the Kinjal, and the Bermamuc, compose a particular chain of
mountains, the highest of the secondary mountains, and the
nearest to the central chain. ‘These mountains form, so to
speak, the rugged edges of a long and wide crevice, from the
bottom of which rises the trachytic chain, against which the
secondary formations which I have described would appear

to lean, if they were not separated by deep vallies, where ‘they |

are seen to perforate several intermediate rocks.

The Kinjal and the Bermamuc, which we have examined
closely, are composed of this grey and compact calcareous rock
which ought to be referred to the limestone with gryphites,
though i in those same points I have not met with those fossils
which in lower points, and in precipices, turned to the central
chain, are mixed with sand, and become at last a true sand-
stone, still older than the sandstone with ostracites. These
two formations rise to the height of 7000 or 8000 feet above
the level of the ocean.

It was in descending towards the upper Ourda, which here —

flows in a deep crevice, that I met with the first intermediary
rocks, and at the same time with lava and amphibolic rocks. ©

The rocks hitherto mentioned are disposed in horizontal
beds, which rise almost insensibly towards the central chain ;
but in the disposition of the intermediary rocks a much greater

with Geognostical Observations, &c. 135

disorder is exhibited. We soon discover the cause of these
derangements. Scarcely has the limestone with gryphites be-
‘gun in the lower beds to mix itself with sand, and to change
into sandstone, when we see it elevated and torn at several
points by black and red lavas, and by compact trachytic masses.
We descended in zig-zag the almost perpendicular declivity of
this mountain; and when we arrived below, we saw to the bot-
tom of a precipice, or of a crevice, on the banks of the Ourda,
which falls impetuously from rock to rock. Here we discover
heaved up strata of argillaceous schistus.

The lavas which are thus found at the limit of the sand-
stone and of the argillaceous schistus are mostly of a black
colour, filled with vesicles greatly elongated in one direction, -
and lying parallel to one another, so that these lavas seem to
have suffered a great pressure by the superposed beds in tra-
versing them. These vesicles are entirely empty 5 and with
the exception of some white points nearly microscopic, we can-
not discover any trace of the substances which so often fill the
cavities of other lavas. Sometimes small crystals of amphibole
are enveloped in their paste. At other places the cavities are
- -very-rare and very small. ‘The mass becomes highly compact,
takes a gray colour, mixed with small spots of a pale red,
cleaves into thin lamine, and presents in general the mineralo-
gical characters of a trachytic paste: The crystals of glassy
feldspar are, however, wanting ; and we discover here and there
small brilliant points of mica of a bronze colour.

The argillaceous schistus alternates in some places with a
species of psammite, (grauwacke,) which is, however, distin-
guished from the common grauwacke by its white colour. ‘The
strata of this rock are very much inclined ; on the banks of the
river Kinjal, which we descended on the same day, the beds
of argillaceous schistus present so many irregularities in their
arrangement, that it is easy to observe the effect of a general
derangement occasioned by the eruption of trachytic masses,
which, as we shall presently see, penetrate every where the
soil of the argillaceous schistus.

The interval between the last sandstone which I have men-
tioned and the argillaceous schistus, is occupied with a parti-
cular formation of gres howiller. This I particularly observ-

136 Mr Kupffer’s Account of the Russian Steppes, ,

éd on the height of Kharbis. This height, which receives its
name because this plateau, which forms only a hollow sur-
rounded with higher mountains, rises a few hundred feet above
the banks of the river Kharbis, forms, where it advances to the
river, and at the same time where it advances towards the cen-
‘tral chain, that is, towards the south, a precipice where the
‘strata of which it is composed are laid bare. We see distinct
alternations of beds of coal some inches thick, with a quartzy
and yellowish sandstone. At some distance to the south, -be-
fore the eye arrives at the central chain, or rather at Elbrouz
itself, which appears from this in all its grandeur, there is seen
rising to a very considerable height a very steep mountain,
with a rugged crest, whose flanks are covered with rocky de-
bris. This mountain has the same physiognomy as the trachy-
tic mountains which compose the central chain. It forms part
of a particular chain which runs parallel to the central chain,
and which we must ascend in approaching the latter. These
mountains, which touch the limit of perpetual snow, are com-

posed of a dioritic rock, whose character is so remarkable as to

merit a special description.

- After having gone along several precipices which Bi

alternately horizontal beds of sandstone and coal, of which all
the district is composed, and whose rugged walls are turned to
the central chain, we descend rapidly into a small hollow which
separates the Youngouché, (this is the name of the mountain,)
from the plateau which surrounds it towards the north. ,. We
ascend again very rapidly, in order to reach a height which
leans to the south on the Youngouché, and forms, as it were,
the first step of it. This height is composed of a sandstone
similar in external characters to that which contains the coal

strata, but which differs from it considerably in the disposition —

of its beds, which are highly inclined, and almost perpendicu-
lar. These strata are supported against rugged rocks, with
which the crest of Youngouché is flanked at its base, and which
consist of an argillaceous schistus, and of a conglomerate form-
ed of fragmentsof quartzand blackish gray jasper (Lydianstone)
cemented by a talcose substance of a pale yellow-green colour,
unctuous to the touch, and of a compound and schistose tex-
ture. At some points this conglomerate takes the appearance

ee a

with Geognostical Observations, &c. 137

of psammite, to which formation it should doubtless be refer-
red. The slope of the mountain is on account of its declivity
so covered with debris that it is very difficult to penetrate to
the rock. Between these debris, beside the rock which forms
the summit of the mountain, and of which I have just spoken,
and the conglomerate also mentioned, pieces of ee ons and
schistoidal amphibole.

The Youngouché itself, that i is, the crest of this mountain,
is almost inaccessible. The ascent of it is dangerous ; the ir-
regular debris with which its flanks are covered slide beneath
the feet, and tumble mto the abyss. The rock of which this
mountain is composed is a diorite, in which compact feldspar
predominates ; it is a grayish mass containing small needles of
amphibole, which sometimes unite into nodules and fill the in-
terior of small cavities. ‘This grayish mass seems to be an in-
timate mixture of feldspar and amphibole; the feldspar pre-
sents here and there points crystallized and whiter than the
rest, so that one is sometimes tempted to take this rock for a
porphyry. Microscopic points of sulphuret of iron are some-
times discovered in it.

The conglomerates which I have described appear also in
various other points situated on the boundary of the trachytic
and secondary district, for example near the cascade of Tous-
loukchapap. ‘The cascade itself is formed of a similar and
very large conglomerate, which rises perpendicularly above
the banks of the Malka to a considerable height. Enormous
blocks, which are no doubt detached from these rocks, obstruct
the bed of this river. On a slope less. steep, upon which our
camp was established, we saw some rocks of serpentine and of
intermediary limestone penetrated by a stratum of the vege-
table soil which covered it.

The stone bridge of Koubun is also formed of porphyroidal
diorite; the dioritic mass is of a pale green colour, and con-
tains white crystals of feldspar. These amphibolic rocks form
here, as they do every where in Caucasus, very rugged moun-
tains, bristled with aiguilles and crests, whose strange aspect
and sombre colour contrast singularly with the flat but rug-
ged rocks of sandstone which follow in the order of their su-

perposition.

138 Mr Kupffer’s Account of the Russian Steppes,

We have seen that the amphibolic and dioritic rocks form
a series of very considerable elevations, intermediate between
the central chain and the chain of the more ancient secondary
rocks, of which the Kinjal, the Inal, and the Bermamuc, form
a part. These rocks seem to have been produced by an erup-
tion which has taken place in the region of the argillaceous
schistus; for whenever they appear, we meet also with masses
of this last rock heaved up in the most regular manner, and
evidently broken and altered by their contact with the dioritic
rocks. The schistose amphibole, particularly, is so confound-
ed with the argillaceous schistus, that it is difficult to distinguish
these two rocks, which sometimes alternate in very thin strata,
and which have the same colour, and almost the same texture
and fusibility. It is almost worthy of remark, that we meet
almost every where in the line of this soil, (the dioritic soil
does not occupy a great extent,) with springs of acidulous wa-
ter containing oxide of iron and carbonate of lime. The
Touslookchapap devives its name from a spring of this kind
which rises at the foot of the cascade. ‘The acidulous spring
near Yesilkol rises out of the ground like that of Youngouché
which I have described. This spring deposits so great a quan-
tity of carbonate of lime that the whole declivity of the moun-
tain is covered with it. The taste of the water is very styptic,
on account of the oxide of iron which it holds in solution.

The central chain of the Caucasus, which rises considerably
above the mountains hitherto described, is entirely composed
' of trachyte. Ata distance it exhibits a series of rugged rocks,
crests, and peaks, whose black summits break in a singular
manner the masses of snow which fill their crevices. These
crests rise to the height of 12,000 feet. The perpetual snow
begins in the Caucasus at the height of 10,000 feet. |

The Elbrouz rises in the middle of these angular masses in
the form of a double-topped cone. The smoothness of its out-
line would distinguish it from the surrounding summits, even
if it did not rise so much above them. Its height is 15,400.
Its advantageous position still adds to the impression which
the view of it makes upon the spectator, for it occupies the
most advanced corner of an angle which the chain of the Cau-
casus forms in this place, as may be seen in the maps. ‘The

with Geognostical Observations, &c. 139

top of Elbrouz is entirely covered with snow, which is easily
kept on its sides, which are generally not very steep.

When we arrive near the middle of its declivity, we perceive
that the lowest trachytic crests which surround it range them-
selves around it, and encircle its base. Elbrouz itself seems
to rise in the middle of a cavity, whose margin is formed by
the trachytic crests I have mentioned. In looking northward
we see the Kinjal, the Inal, and the Bermamuc, present the
same arrangement. All these mountains exhibit precipices
turned towards Elbrouz, or towards the central chain ; while
to the north they slope insensibly, and form the immense pla-
teau of which we have already spoken.

The trachyte, (é. ¢. all the porphyries which envelope in their
mass crystals of vitreous feldspar,) which compose the sum-
mit of Elbrouz itself, holds a middle place between the resinite
feldspar and the obsidian porphyries. Its mass, which enve-
lopes many white crystals of glassy feldspar of an average dia-
meter of two or three lines, is black and opaque, of a rough and
uneven fracture, and of a vitreous aspect. On the fissures
which traverse it in al] directions, and which divide it into
masses ‘of a form approaching to that of the parallelipiped, it
is coloured red, probably by the oxidation of the oxide of iron
which it contains. Small scales of black amphibole and of
black or bronzed mica are disseminated through the mass.

The approaches of Elbrouz present the picture of destruc-
tion. Enormous blocks of the trachyte which I have describ-
ed are heaped one upon another. ‘Their debris cover the bot-
tom of the excavations, and of the high valleys which sepa-
rate them. These debris often preserve, while decomposing,
their salient edges, and prevent the formation of vegetable soil. _
Though traversed by a thousand brooks fed by the melting of
the snow, the ground is parched, and rolls down with a noise
beneath the feet of the traveller. The rocks which I collect-.
ed during this ascent present different varieties of trachyte
and lavas; they are disposed without order, and they obstruct
the beds of the rivers, particularly that of the Malka, from
which I have obtained a great number of them.

Among these we particularly distinguished a lava of very
porous and grey feldspar, which envelopes white crystals of

140 Mr Kupffer’s Account of the Russian Steppes, &e.

glassy feldspar, and small scales of black mica. This lava re-
sembles much the trachyte of Elbrouz in its composition, dif-
fering from it only in the porosity of its mass. The cavities
or-vesicles are elongated in a determinate direction, and: ar-
ranged in strata, a very distinctive character, which seems to
belong to all these melted masses. This character sometimes
vanishes ; the mass becomes more compact, and its colour more
sombre. The rock is thus a true trachyte with a base of ob-
sidian, which perfectly resembles that of the summit of Elbrouz.
Other specimens have a pale violet colour, with the aspect
of wacke, enveloping also crystals of glassy feldspar and scales
of mica. I have also met with specimens in which very thin
strata of black trachyte, with a base of obsidian, alternate with
a red and very porous scoria.

' The porous feldspar lavas with crystals of glassy, feldspar,
which I have mentioned, rarely envelope portions of hyaline
quartz. These portions are very transparent, and often crack-
ed, so that they separate into several grains when touched with
the point of a knife. T hese grains, however, preserve the or-
dinary hardness of quartz. These gray lava sometimes become
so porous, that they form very light masses, decomposed at
the surface, white and similar to pumice-stone, which they re-
semble also in roughness. The debris of this rock forms accu-
mulations, which we have several times observed in deere:
from Elbrouz.

There still remains to be described a particular bart which
I have frequently met with in returning from the summit of
Elbrouz. This rock consists of a grayish-white feldspar ce-
ment, enveloping grains of hyaline quartz, small needles of am-
pkibole, and scales of black mica. The cement crystallizes at
some points, and then presents the structure of glassy feldspar.
This rock exhibits the same stratiform structure which belongs
to all the lavas of the Caucasus, and which _ gives to all these
rocks the appearance of having flowed in a certain direction.
On the banks of the upper Malka we still meet with large.
blocks of red and green jasper enveloped in the same black vi-
treous trachyte which we have above described.

In all our journies in the Caucasus, I have met with gra-
_ nite only in the hollows excavated by the rivers ; but we know.

Prof. Moll on the inflammation of Phosphorus. 144

from the observatiens of MM. Engelhardt and Parrot, that it
is found in interlaced strata in the argillaceous schistus. There
have been brought to me pieces of granite and gneiss detached
from a rock near the source of the Malka. According to the
information I have obtained respecting the position of this gra-
nite, it occupies all the bottom of the vallies, never rising to a
great height, and is co-ordinate with the argillaceous schistus.
I have been assured that the black trachyte of the central chain
has been seen expanded over several of the beds of granite
which are met with at the foot of Elbrouz, while ascending
the river Malka. ,

- The granite which I have met with in the bed of the
Malka is composed of common white feldspar, with a little
quartz and silvery mica. The mica is disseminated in it in la-
mine pretty large and distinct, which gives to this granite the
appearance of gneiss.—See our last Number, page 351.

—--

Art. XV.—ZHistorical Notice respecting the Inflammation of
Phosphorus in Vacuo. Ina Letter to the Editor by Pro-
fessor Mott.

- My Dear Docror, Utrecht, 26th May 1831.

Tuenre isa statement in one of the last numbers of your Jowr-
nal which, if not altogether erroneous, is certainly at any rate
not quite correct. I hope you will excuse me if I attempt to
set you right. It concerns the combustion of phosphorus in
vacuo, or as you express it more justly, in No. 8, p. 370, of
your Journal, in a partial vacuum. That experiment is attri-
buted by many to a countryman of mine, of the name of Van
Bemmelen, who by a misnomer in English and French peri-
odicals has heen sometimes called Van Bemmeleer. That wor-
thy gentleman, since deceased, cannot claim by any means the
honour of the invention of this very singular experiment.
This honour belongs entirely to my venerable and celebrated
friend Dr Van Marum, who as far back as 1794, observed this
curious phenomenon. He published his experiments as early
as 1797 in a Dutch collection of chemical tracts, called Kaste-
leyn, Chemische Oefeningen, vol. i. p. 249. Soon after he gave
an account of them in French, in the Description de quelques

142 Professor Moll on the inflammation of Phosphorus.

Appareils Chimiques du Musée de Teyler, No. 10, p. 40.
This was repeated in the Annales de Chimie, 'T. xxi p. 158,
and in German in Gren’s nedes Journal der Physik, T. iti. p.
96. Mr Van Marum’s experiment was this, that phosphorus,
lightly wrapped in dry cotton, or in cotton powdered with re-
sin, would inflame in vacuo of a good air-pump.

In 1801, the late Dr Van Bemmelen published an account
of the repetition of Dr Van Marum’s experiments. He found,
however, that phosphorus powdered with resin, or sulphur,
without being wrapped in cotton, would inflame equally well,
and that the experiment succeeds also when phosphorus is cover-
ed with volatile oil of cloves. But neither Dr Van Marum,
nor his friend Dr Van Bemmelen could succeed in inflaming
phosphorus, not covered by or wrapped in some other sub-
stance ; this appears to have been effected by the transatlantic
philosophers, according to the very brief account of their pro-
ceedings given in the Edinburgh Journal of Science. Van
Bemmelen’s tract was in part printed in German in 1828, in the
late Professor Gilbert’s Annalen der Physik, neve folge, T. xxix
p- 268. Nearly at the same time in 1827, another paper, on
the same subject, was published in Dutch by a clergyman of the
name of Koning, and this tract, to which a golden medal was
awarded by the Zealand Society of Arts and Sciences, is to be
found in the second part of the fourth volume, of their Transac-
tions. (Nieutve Verhandelingen van Zeeuwsch Genootschap.
4de deel, 2de stuk.) I have seen the experiment frequently re-
peated in public lectures, I often repeated it myself, but I never
saw or heard of a satisfactory explanation of so uncommon a phe-
nomenon. ‘This difficulty of accounting for the result was per-
haps the cause why the experiment was scarcely ever mention- |
ed in any book on natural philosophy or chemistry ; and except:
m Holland, it does not appear that the experiment was much:
noticed or even repeated. The thing appeared almost forgotten,
when Mr Berzelius was struck by the abstract of Bemmelen’s —
experiments in Gilbert’s Annals of Physics; of this abstract
another abstract was made in Mr Berzelius’s very valuable year-
ly account of the state and progress of natural science ; from
thence it gradually. penetrated into almost all the scientific
journals of Europe. As, however, Mr Berzclius had made

Observations on Monochromatic Laight. 143

unfortunately the mistake, of attributing the invention of the -
experiment to Mr Van Bemmelen, all the other editors of
scientific journals followed in the same track, and Dr Van
Marum has a fair chance of being deprived of the credit of an
invention, which he made fully thirty-seven years ago, and of
which accounts were printed in the most popular French and
German scientific periodicals of the time. My venerable and
much respected friend feels justly vexed at this, and I trust to
your love of truth and justice the care of setting the public right
on this subject.—Y ours very sincerely,
G. Mott.

Art. X VI.—Remarks on Dr Goring’s Observations on the use
of Munochromatic Light with the Microscope.

Tue value of practical science, and the superiority of the re-
sults of accurate experiments to the deductions of theory, are
universally acknowledged, and by none more readily than those
who are principally occupied with abstract research. When
the calculated results of general laws are found in direct oppo-
sition to those of accurate observation, the philosopher is on
‘the eve of some important discovery; but whenever such an
opposition presents itself, he will be careful to repeat his ex-
periments, and he will not venture either to assail the correct-
ness of a well established and universally admitted law, or to |
seek for the new principle on which the discrepancy depends,
till these experiments are placed beyond a doubt. While we
admit, therefore, the transcendent value of practical science,
we must so far take the part of theory as to insist upon a ri-
gorous scrutiny of the facts by which it is opposed.

As I was the first person who recommended the use of ar-
tificial monochromatic light for microscopical observations, by
arguments drawn not only from theory but from immediate and
frequently repeated observations, and as Dr Goring’s observa-
tions, as recorded in a preceding article, are, if correct, entirely
subversive of mine, it is necessary that I should relieve science
from the opprobrium of these contending opinions. As Dr

144 Observations on Mohochromatic Light.

Goring’s experiments were made with monochromatic light
such as his prism could give him, while mine were made with
the infinitely superior illumination of the yellow light of amo-
-nochromatic lamp, I might have satisfied myself with the reply,
that the results which he obtained with the one could not pos-
sibly invalidate those which I obtained with the other; but
this would have been a virtual evasion of the difficulty, for I
am convinced that monochromatic light properly obtained by
the prism is as well fitted for microscopic vision as that of a
monochromatic lamp, provided we use a portion of the pris-
matic spectrum that has the same limited range of refrangibi-
lity. ‘This, however, is almost impossible, and hence the great
superiority of artificial yellow light is undeniable.

The conclusion at which Dr Goring arrives is, that white
light is as good for microscopical vision as the monochromatic
light which he obtained from the prism,—that such light is
not monochromatic,—and that a monochromatic light is still a
desideratum. The proof which he gives of these conclusions
is this: When any of the prismatic colours were employed to
illuminate the microscopic object, the object was fringed with
prismatic colours. Of the accuracy of this observation we
cannot doubt; but it is manifest that the prismatic colours
employed were compound, and were either formed by an im-
perfect prism, or mixed with extraneous light. Instead of
suspecting the goodness of his prism, or his method of observa-
tion, Dr Goring is led to infer that a certain quantity of white

light enters into the constitution of each of the seven coloured
rays, and may be rendered manifest by the dispersive powers of
prisms and lenses.—This result is in direct opposition to all Sir
Isaac Newton’s experiments with the prism; andif Dr Goring
will employ the methods suggested by Sir Isaac for obtaining
homogeneous light, he will discover the origin of his mistake.
As this, however, would be attended with some trouble, we
beg to suggest the following experiment which we have made
fifty times with the same result. Take an excellent prism,
capable of showing -Fraunhofer’s lines in the spectrum, and
having admitted the sun’s light through the narrowest practi-
cable opening between the edges of the window shutters, fix
the prism vertically at the tar ic of twelve or fifteen feet, so

Observations on Monochromatic Light: 145

as to see through it a prismatic spectrum of the luminous aper-__
ture. Take another prism equally good, and view. through it
any portion of the, first. spectrum, by refracting that portion
towards the violet extremity, and it will be seen that it is perfect-
ly unchanged in its nature and colours by the second refraction.
The lines will be seen as distinctly as before, and nota vestige
of any other colour will be seen but that of the coloured por-
tion itself. .

In reference to the perfection of monochromatic vision, the

following experiment will be decisive. Place a printed page

of a small type upon a table illuminated by the sun. Stand-
ing at the distance of some feet, view this page through a
prism so that the plane of its refraction is parallel to the lines
im which the types are arranged. The print will be entirely
legible, each letter being blurred with a prismatic spectrum
of -the white spaces between the sides of the types. Let the
page be now illumimated by the light transmitted through a
leaf of red paper, and the words and letters will be distinetly
legible, though still indistinct on account of the red: light not
being homogeneous. Shut the window shutters, and. illumi-
nate the page with a monochromatic lamp: The words and
letters will now be beautifully sharp and distinct, and except-
ing their slight expansion in one direction by refraction, they
will be as clearly seen as if they were viewed through a plate
of parallel glass, or with the eye alone.

If Dr Goring will therefore substitute the monochromatic
lamp in place of the sun, we have no doubt that he will change
his opinion on the subject of monochromatic vision, and if his
health will permit him to devote his acute mind, and apply his
great practical knowledge to microscopical discovery, we pledge
ourselves that he will find monochromatic light the most power-
ful instrument of discovery which optical science can at present
command. _ Hogty

In the use of single chromatic microscopes, a great deal may
be done to improve the image, and even free it from colours
when particular kinds of objects are used. Let it be required,
for example, to determine the place of an object consisting of
close parallel lines, in order to obtain the most perfect vision
of it by a single chromatic lens.—The lens should, in the first

NEW SERIES, VOL. Vv. NO. I. JuLY 1831. K

146 Observations on Monochromatic Light.

place, have its axis horizontal; because in this case the eye is.
in its natural position, and the fluid which lubricates the cor-
nea is more evenly diffused over it by its gravity. If the axis
of the eye were vertical, the fluid would tend to accumulate at
the centre of the cornea, and produce a less perfect refraction
of the incident rays. The direction of the lines in the micro-
scopic object must be vertical, or parallel to the lines in which
the fluid descends over the cornea, because in this position
their sharpness will be least affected by the descent of the
fluid. And, lastly, the direction of the lines should be in that
of a diameter of the field of view passing through the axis of
the lens, because in this position all colour whatever will dis.
appear between the lines, as the plane of refraction in the
lens is comcident with the lines; a case in which the largest
refracting angle of the most dispersive prism is incapable of
producing any colour in a line of light. When the lined ob-
ject is placed out of the centre of the field, the prismatic co-
lours will immediately appear at the edges of the lines, but
this species of colour may be corrected by the opposite refrac-
tion of a prism ; or even by looking past the edges of the fin-
ger, so as to produce a compensation by the chromatic effect of
the eye. This last resource will of course obstruct a good deal
of light, and is mentioned chiefly for the sake of illustration.
We leave it to the mathematicians to deal with the remain-
ing part of Dr Goring’s paper, which displays great practical
knowledge of optical instruments, and contains much original
and valuable information ;—but we cannot avoid touching up-
on one topic. Dr Goring has in page 67 quoted a passage
‘from Mr Coddington’s preface to his T'reatise on the Eye and
Optical Instruments, which has no doubt compelled him to take
up the gauntlet thus thrown down to every improver of the mi-.
croscope. The following is the passage referred to, which has
given just grounds of offence, not only to those who have suc-
cessfully devoted their time and their fortune to the improve-
ment of the microscope, but to those also who feel that English
science might justly boast of its achievements in this department’
of optics. While the French and Bavarians have been carrying
off from. us the palm in achromatic telescopes, it was some con-

Observations on Monochromatic Light. 147

solation that we still surpassed them in nilycigs! segs speak improve-
ments.

On the subject of telescopes,” says Mr Coddington, * I
have done little more than detail and explain to the student
the improvements which the talents and industry of Huygens,
Dollond, and Ramsden, had long since made available in prac-
tice. With regard to the microscope, I may perhaps lay claim
toa little more. That instrument had, till very lately, been
almost entirely neglected since the days of Campani, and I am
inclined to doubt whether the intellectual and manual labour
which has within a few years been bestowed upon it have
been on the whole profitably directed, since they have left
wholly untouched a source of error perhaps the most import-
ant of all, namely, the ppbawity of the refraction at the ob-
ject-glass.”

We entirely agree with Mr Coddington in the opinion, that
the microscope has been almost entirely neglected since the days
of Campani; but we differ widely from him ‘in his estimate of
the value of the intellectual and manual labour which has been
lately bestowed upon it.—We regard the last twenty years as
the golden age of microscopical improvement ; and in proof
of this position, we shall enumerate some of the intellectwal and
manual labours by which this period has been so remarkably
distinguished.

“1. Dr Wollaston’s introduction of centrical pencils by
means of two hemispheres separated by a diaphragm.
2. Dr Brewster’s grooved or excavated sphere, very inap-
propriately called the bird’s-eye lens by Mr Coddington.
3. The catoptric hemisphere, by which the magnifying
power of a hemisphere is doubled.
4. Mr Herschel’s double lenses free from spherical aberra-
tion. !
5. Dr Wollaston’s microscopic doublet.
6. Dr Wollaston’s improved method of illumination.
7. Introduction of monochromatic light.
8. Introduction of microscopes made of garnet, a
and diamond.
9. The improved Amician reflecting microscope.
10. Selligue’s idea of combining achromatic object-glasses.

148 Notice of the Discovery of the Termination of the

11. Dr Goring’s various improvements on the microscope,
as described in this Journal and elsewhere; and his introduc-
tion of test objects. See this Journal, No: xx. Old Series,
p- 327, 360; No. i. New Series, p. 64, 353; and No. viii.!
p. 244. See also the T'reatise on the Microscope published
by Dr Goring and Mr Pritchard.

12. Mr Lister’s discovery of the double aplanatic foci, and:
variable aberration of achromatic object-glasses havidg their
inner curves in contact. |

In the preceding enumeration we do not pretend to give’ ani
exact list of recent microscopical improvements; We have’
merely mentioned those that happen to be best known to our-
selves. ie

With regard to manual labour, we may give the following
enumeration :—

1. The new and difficult art discovered by Mr Pritchard
of making diamond lenses.

2..The great skill exhibited by Chevalier, Tulley, Anil
Utzschneider, and others, in constructing minute achromatic:
object-glasses.

3. The art of giving the elliptical form to small spain
3-10ths of an inch focus, and of the same aperture, as perl
by Mr Cuthbert. See this Number, p. 74, note.

This enumeration of facts will, we hope, relieve the philes
sophers and opticians of England and other countries, from
the charge of having given an unprofitable direction to their:
intellectual and manual labours in the improvement of the mi-
croscope. That their inquiries have been pursued in the right:
direction, may be safely inferred from the extraordinary success
with which they have been attended.

é

Ant. XVII.—Notice of the Discovery of the Termination of
- the Niger, in the Bight of Biafra. |

Tne discovery of the termination of the Niger has long been —
a problem of some interest in geography. ‘The direction of the
river seems to have been traced toa point in 10° of north lati-
tude, and 5° of west longitude, a little to the south of Yaory
or-Youri, the place where Mungo Park appears to have been

* Niger in the Bight of Biafra. y 149

wrecked. At this point the Niger, or the Kowara or Quarra,
as it is there called, is within less than 4° of the Bight of Benin,
in the Gulf of Guinea, but no correct information could be ob-
tained respecting its future course. According to information
given to Major Denham it then took a direct easterly course to-
wards the Nile, and the very same direction is assigned to it in
Sultan Bello’s Map of Central Africa. An able writer in the
Quarterly Review supported this view of the subject with
great ingenuity. According to the hypotheses of Major Laing,
and from information communicated by the Sheikh of Gadamis,
the Niger went westward, passing through the mountains of
the Moon, and terminating in the River Volta, in the Bight
of Benin, in north lat. 53° and east long. 1.° Captain Clapper-
ton was led to give it a course straight south from Youri, and
terminating in the Bight of Benin, to the east of Lagos, in
north lat. 64° and east long. 43 ; while according to the hypo-
thesis of Reichard, a German geographer, it went a little far-
ther to the east, terminating in the Bight of Benin, and forming
the great River of Formosa in Benin, in north lat. 4°, and east
long. 5}°. Other travellers, such as Mungo Park and Cap-
tain es Well identified it with the Congo or Zaire.

Of all these hypotheses that of Reichard is the nearest to the
truth, as it has been found to terminate in the Nun or Brasse
River, in the Bight of Biafra, in north lat. 43° and east long. 9°,
just at the great angular point of the African continent, a little
to the north of the Island of Fernando Po.

This great discovery was made by the two Landers, one of
whom accompanied Captain Clapperton, and attended that ad-
venturous traveller on: his deathbed at Sockatoo- In 1830,
Mr Landers, accompanied by his brother, sailed to Africa,
and succeeded in tracing the Niger to the sea. The following
account of the discovery was communicated to the Editor of
the Literary Gazette by Mr Fisher.

“ His Majesty’s Ship Atholl, at sea,
: Bight of Biafra, Feb. 2, 1831.
« Dear Sir,—I take the opportunity of writing you a few.
lines by a.vessel that we have just now met on her way to”
England. My object in writing in this hasty manner is to ac-

150 Captain Franklin on the Diamond Mines of

em you that the grand geographical problem reepecaiag the
termination of the Niger is at length solved.

** ‘The Landers, after having reached Youri, onhesiiill ina
canoe on the Niger, or, as it is called there, the Quarra, and
came down the stream until they reached. the sea, in the Bight
of Biafra. The branch by which they came to the coast is
called the Nun, or Brasse River, being the first river to the
eastward of Cape Formosa. On their way down the river, they
were attacked by the Hibboos (a fierce nation that inhabit its
banks), and made prisoners, or rather captives ; but the King
of Brasse happening to be in that country buying slaves, got
them released, by giving the price of six slaves for each of
them. In the scuffle that ensued at the time they were sakem
one of them lost his journal.

** Whilst at Youri they got the prayer book that sake
to Mr Anderson, the brother-in law and fellow-traveller of the
celebrated Mungo Park. They were upwards of a month at
Fernando Po, whence they embarked, about ten days ago, in
an English merchant vessel bound to Rio Janeiro, on their way
to England. From their taking that circuitous route, [ am in
hopes that this will reach you before they arrive, by which you
will probably have it in your power to give the first news of
this important discovery.

** I do not recollect of any thing else to acquaint you with
that is worthy of notice ; and even if I did, I have no time to
mention it, as the boat by which I send this (to the vessel) is
just this moment ordered away.

‘** I must therefore bid you adieu for the present ; and be-

lieve me, dear Sir, yours very sincerely,
“© ALEXANDER FisHer.”

Ant. XVIII.—On the Diamond Mines of Panna in Bundel-
khand. By Cartaix JAMEs Frank tn, First Bengal Ca- —

valry, M.A.S.

Tur geological position of the matrix of the diamond, being
still a question in the history of that gem, the following notice
on the diamond mines of Panna, will not, I trust, be wnac-
ceptable.

Panna in Bundelkhand. 151

~ Report says, that they were first discovered in the time of
Raja Chitras4l, who ruled at Panna, in the reign of the em-
peror Aurangzeb, but that period being a troublesome zera in
the annals of the Bundelas, it is supposed, that they were not
efficiently opened, until the time of his grandson Subha Sinha. -

Their situation is peculiar, being confined to a small portion
of the great belt of sandstone which extends from Rotasgerh,
through the provinces of Boghélkhand and Bundélkhand, un-

til it is finally covered by the overlying trap of Malwa and
_ Sdgar ; this, however, is but a small part of the extent of this
formation, for the break at Rotdsgerh is merely an hiatus oc-
casioned by the original current of the Sean valley, which -
doubtless swept away every vestige of this rock, until its force
was turned aside by the projecting points of the Vindhya range,
near Monghir,—after which in the Rajmahal hills, the sand-
stone again appears as before,—and from that point it may be
traced throughout the whole of the peninsula; it is the depo-
sitary of the diamond at Panna—and I have no doubt that
the rock mines both of Sembhelpur and Banganpilli, though
far asunder, will ere long be found to belong to the same for-
mation; in the meantime, the following facts which have fal-
len under my own observation, on my route from Belari to
Ajayagerh, may serve to identify the class and character of
the rock which contains the matrix of the diamond of Panna.
- The first part of the route (or from Belari to Ajayagerh)
crosses the most lofty portion of the sandstone belt, usually
called the Bandair hills—which, without exception, is entirely
composed of argillaceous sandstone, either mottled or streak-_
ed—and opposite to the village of Piperiya, below the Ghat
of that name, I observed the sandstone reposing on beds of
slaty marl.

Having descended the Bandair hills by the Ghat of Piper-
iya, I came upon the second range, which, like the former, is
composed of sandstone, but the surface of its plateau being co-
vered with a stratum of lias limestone, the sandstone can only
be traced in the beds of rivers, or in small protruding elevations,
until it emerges from beneath the limestone and forms the
counterscarp of the Panna hills, where it is variegated and

152 Captain Franklin on thé Diamond Mines of

friable, and the marly slates are again visible in the hills vane
overlook the town of Panna. |
The lowest portion of the range, or that whindes is called Bin-
dachal, is the peculiar habitat of the diamond, for it is not
found in any other part, except on the platform of this range,
or on the counterscarp of the second, and it is proved by the
waterfalls, that this range also is entirely composed-of sand-
stone. For instance, the cascade of the Ranj river shows a
series of sandstone interstratified with slate clay three hundred
and ninety feet thick. All the other waterfalls present simi-
lar appearances, and that of the Bagin river, penetrating
deeper than the rest, exhibits a fine section; -here the sand-
stone is distinctly interstratified by a succession of layers of
slate clay, the uppermost of which having a marly base is
thickest, and the descending strata becoming more indurated,
containing more mica, and gradually diminishing in thickness,
dwindle away finally into mere partings, and in their progress
to this attenuated state, they assume characters. so various,
that in some instances, it is difficult to distinguish them from
the older schists. The sandstone also changes, gradual-
ly becoming silicious, and at the bottom it closely -resem-
bles some varieties of quartz rock, but the horizontal position
of the beds is constantly preserved, and in _all-the glens, par-
ticularly in that of the Bagin river, black bituminous shale
crops out from beneath the sandstone. I excavated this shale -
to the depth of six feet, but having no other means than such, .
as I could procure on the spot, the influx of water soon over-
powered my operations. I found, however, that the bitumi-.
nous quality of the shale increased,—fragments of it, throwing.
out strong shoots of flame when ignited, and I was disposed to,
think that coal was not far distant.
I have ventured to call this formation new red sanidatpee,
considering it in the same light as the series of rocks so term~
ed in England, and it would appear, that this denomination,
is in some measure corroborated by other. facts, in other por-
tions of the same range of hills, but principally by the proof
of its saliferous nature. It has been shown, that at the village
of Kattra, the soil is impregnated with salt, which. is. there,
and in many other adjacent villages, extracted by the native

Panna in Bundelkhand. 153

process of lixiviation, such is the case also on the banks of the
Tons river, and Mr Stirling, who published an account of the
diamond mines of Panna, remarks, that salt abounds in the
soil at the foot of this range, opposite Allahabad, and between
that place and Mirzapur. These facts, therefore, together
with the general horizontal position of the beds, the existence
of lias limestone reposing upon them, the distinct interstratifi-
cation of a series of slate clay, and above all, the.croppmg out
of bituminous shale from beneath the whole :mass, would ap-
pear to justify the use of the term which I have applied.

I have been thus prolix, because it is of importance that I
should be clearly understood with regard to my nomenclature,
and, if I am wrong, my own description may, perhaps, serve
to correct my error. Having thus premised, I shall now pro-
ceed to give as brief.a description as I can of the mines in
question. .

The natives describe the mines by using the terms chi/a, or
superficial, and gahira, or deep, and the matrix they call
madda ; the rocky matrix of the deep mines is always a con-
glomerate, and, if it is a gritstone with a silicious cement, and
its pebbles are of ancient rocks, and waterworn, it is termed
pakka or mature; but if the cement is argillaceous, and _ its
_ pebbles are of more recent rocks, it is then called -kacha,. or
immature ; the matrix of the. superficial mines is universally
called Ld/kakru, or red ironstone gravel, mixed with ferrugi-
nous sand or clay. This gravel is waterworn, and sometimes
quite rounded like swan shot, and when found in the fissures
and interstices of the upper sandstone, it is mixed with ferru-
ginous sand, but, on the other hand, when imbedded in ferru-
ginous clay, it-is usually found covered with vegetable soil,
and reposing upon slaty marl ;—sometimes, however, it is sur-
mounted by a stratum consisting of particles of common kankar
imbedded in yellow clay, which occasionally mingling with it,
forms another description of matrix, which, being calcareous,
is called hadda ; the diamonds of the glen of the Bagin river,
have evidently been transported thither from their native beds,
and in all probability the gangue in which. they now rest in
the basin of the waterfall, greatly resembles the: cascalho of
the Brazils, or that of Sambhelpur, in Southern. India.

154 Captain Franklin on thé Diamond Mines of

The pakka, or rocky matrix, 1s very limited, stretching: ge-
nerally from Kamariya to Brijpur, along the course of the
Bagin river. It is excavated at Kamariya, Bijpur, Bargari,
Myra and Etwa; their is also a small deposit of it near the
town of Panna, but at Brijpur, from the effects of denuding
causes, it lies at the surface, and a very satisfactory section of
it is laid bare in the bed of a small rivulet about one mile west
of the village, where it appears to be a gritstone, composed of
white quartz gravel, cemented by silicious matter, and con-
taining rounded pebbles of quartz, jasper, hornstone, Lydian-
stone, &c. Thus it forms a conglomerate, which passes by
gradual transition into silicious sandstone. It is readily dis-
tinguished from its associated rock, differing greatly from it,
in as much as the sandstone in which it is found has a martial
argillaceous cement, and closely resembles that which forms
the upper layer of the cascade of the Bagin river.

Kamariya Mines.—The most noted ‘mines of this desittip.
tion of matrix are those of Kamariya and Panna; at the for-
mer place they are on an average about fifteen feet deep, and
in one which I examined, the beds of slaty marl were two
feet below the surface, a thin stratum of red ironstone gravel
imbedded in ferruginous clay, and vegetable soil, were their
only covering ; they differed in no respect from those of Pi-
periya Ghat, they were marly, slaty, slightly micaceous, in-
terstratified with thin laminze of sandstone, and associated with
calcareous slates, which were dendritic between their partings,
and although their general colour was bluish-green, or greenish-
grey, yet there was a sufficient mixture of red, to characterize
them ; they were about twelve feet thick, and immediately. be-
low them was the rocky; matrix of the diamond. r

The conglomerate is here as. at Brijpur, a gritstone contain-
ing pebbles of quartz, both white and green jasper, hornstone, -
Lydianstone, &c. and it is worthy of remark, that when the
green quartz pebbles abound, it is considered a good sign, and
so also when the gritstone is slightly ferruginous, the matrix

in these mines reposes on compact sandstone.

Panna Mines.—The mines of Panna are of the same itd: &
here also the stratum beneath the vegetable soil is red ironstone
gravel, below which are beds of slaty marl, better characterized

Panna in Bundelkhand. — 155

if possible than those of Kamariya, then follows the diamond ma-
trix, which differs in no other respect from that of Kamariya or
Brijpur, except that it appears to contain a little more ferru-
ginous matter; its pebbles are the same, its cement the same,
it has the same peculiarity of containing green quartz nodules
so highly esteemed as an augury by the natives, and its floor
is of the same description of sandstone.

These mines vary in depth from twenty to fifty feet, and,
owing to the stratum of the matrix being thinner, (sometimes
scarcely a span thick,) they cannot be worked laterally as at
Kamariya, they are therefore more expensive, but their pro-
duce is said to cover the outlay and yield a profit. They are
consequently esteemed, and hold a reputation nearly equal to
those of Kamariya.

Sakertya Mines.—The kacha, or immature matrix, is ex-
cavated at the villages of Sakeriya and Udesna, both situated
on the counterscarp of the Panna hills. It contains rounded
pebbles of quartz, jasper, Lydianstone, &c. but with these are
mixed more recent pebbles of white sandstone. It contains
also much white quartz gravel, called by the natives, detla, but
the cement of the conglomerate, instead of being silicious, is a
yellowish white clay, soft and plastic when in its natural bed,
but capable of acquiring the consistency of mortar when ex-
posed to the atmosphere, and when it contains ferruginous
matter it is considered a good sign. The quartz pebbles are
of the fat and greasy variety, and the green kind so much es-
teemed in the rocky matrix, is here entirely wanting.

A shaft near Sakeriya which I examined, pierced through
the following beds Ist, eight feet vegetable soil; 2d, eight
feet piri matti, or common kankar, imbedded in yellow clay ;
3d, four feet lalkakru, or red ironstone gravel in ferruginous
clay ; 4th, two feet detla, or white quartz gravel; next fol-
lowed sandstone, and then the kacha matrix. The thickness
of the detla stratum is here considered a matter of augury ; if
it is too thick it augurs ill, as it is then supposed that the stra-
tum of madda will be correspondently thin, or wanting altoge-
ther. It ought not to exceed two feet.

Udesna Mines.—Near the village of Udesna, the same kind
of matrix underlies laterite, there called macha. The great

156 Captain Franklin on the Diamond Mines of

abundance of ironstone gravel and ferruginous matter strewed
over this part of the country necessarily produced in former
times, and no doubt still continues to produce, a great quanti-
ty of oxide of iron, which being washed away, and held in.so-
lution by the minor streams, has been gradually deposited in
the channel of the Ranj river until it is now about ten feet
thick, and immediately below it are the beds of detla and sand-

stone, and the matrix as above-mentioned. This matrix does
not require to be broken, the clay is easily separated by wash-

ing, and the expence of working the mines is consequently les-
sened, but still they are not considered so certain in their re-
turn as those of the rocky matrix.

Superficial Mines.—The chila, or superficial mines, are to
be found in every part of the diamond tract, excepting only a
circuit.of about five miles from the cascade of the Bagin river,
where it appears that denuding causes have swept them away
and all their contents into the glen of that river. Their ma-
trix is always red ironstone gravel in ferruginous sand or fer-
ruginous clay. Their geological position, with regard to the
descending series, appears to be remarkably well defined, for
they are obinly to be found on the verge of two cascades,
having 400 feet of sandstone beneath them ; when this matrix
fills the fissures and interstices of the upper sandstone, angular

fragments of the rock are mixed with it, the corroding influ.

ence of the oxide of iron appearing to have detached them as
well as to have disintegrated and oxidated a portion of the
rock, so that the gravel and fragments are imbedded in sand
so highly ferruginous that it resembles the rust of iron; but
when, on the other hand, it is imbedded in ferruginous clay,
it contains no fragments of sandstone, and is constantly found
overlying slaty marl or sandstone, or deéla, as in the instances

above-mentioned ; with regard to the ascending series, its geo-

logical position seems also to be well defined, for, if the two
strata of red ironstone gravel and kankar occur together, as
they do at. Sakeriya, it always underlies the calcareous bed,
and their line of separation is.distinct, so that, when they hap-

pen to mingle as at Bangla, the matrix acquires a new pear
and is then called hadda. |

These mines rarely exceed five or six ck in depth, and are .

3

PE ee ee ee

SS ee ee eee

Panna in Bundelkhand. | 157

often much less; with regard to their produce I am inclined to
think that they are very precarious, notwithstanding some of
the largest diamonds have been found in them; it is‘common
to hear complaints of having found nothing for many months,
and: to me they appeared like a lottery in which there are a
few prizes and many blanks—they have an advantage im re-
quiring little or no outlay, and are consequently wrought by
all classes, but it is not unlikely that more capital has been
sunk in them in the shape of labour than has ever been re-
turned.

The diamond is occasionally, though very rarely, found on
the surface, nor is it improbable that some lucky chance of this
kind may have led to the discovery of the mines.

Mines of Transported Diamonds.—The above is a brief
account of all those matrices of the diamond in the Panna dis-
trict, which fall under the denominations of madda, lalkakré,
or hadda ; but there are others where the gem is found in de-
posites with which it appears to have been swept away from
its native beds, as at Majgoha and in the glen of the Bagin
river; the mines of the former place are peculiar, and require
separate mention, but in those of the glen, the diamond is found
under rocky debris, both on the banks and in the bed of the
river, and also in the basin which receives the cascade ; its ma-
trix in this state, is a confused mixture of red ironstone peb-
bles, angular fragments of sandstone, and pieces of common
kankar, heaped together in ferruginous sand or clay, the de-
tritus in fact of its original gangue; and the mines of course
have a great resemblance to the superficial mines above-men-
tioned, but they are said to be rather more productive, and
there is great reason to believe that the basin of the cascade
has never yet been emptied or excavated except to a trifling
extent.

Majgoha Mines.—The mines of Majgoha are in the west-
ern part of the diamond tract, and they may properly be called
its western boundary ; they are situated in a hollow resem-
bling an inverted cone, which appears to have been excavated
by the same process, (more powerfully applied,) which scooped
out those resemblances to it in miniature, which are observ-
able in the rocky beds of rivers ; the diameter of the vortex is

*
158 Captain Franklin on the Diamond Mines of

about 100 yards, and its depth (I presume) cannot be less
than 100 feet ; on its periphery, superficial mines are wrought
_in sandstone, but the cavity of the chasm is filled with green
mud, containing calcareous matter, such as I can find no apt
similitude to, except by supposing it to be the abraded mat-
ter of the same marly slates as those which occur in the mines
of Panna and Kamariya, here deposited en masse, and there
in slates ; this of course is mere conjecture, but if the vortex
has been formed as I suppose it to have been, the matter
could not in that case have acquired a schistose form; ‘be the
facts of the case, however, what they may, this singular de-
posite fills two-thirds of the chasm, and at the top it has a thick
crust of calcareous spar, which is indistinctly oe and
contains portions of the green mud between ‘its laminee. —
The diamond is rarely found in the calcareous crust, its
habitat being in the green mud, and it is believed by the na-
tives, that the deeper a shaft descends, the richer is the pro
duce ; but although they are aware of this circumstance, their
ordinary means have never enabled them to descend lower than
fifty feet, the water at that depth overflowing their works, and
compelling them to desist: this deposite, therefore, and that
of the basin of the Bagin river, appear to be two instances in
which superior means sagt be employed, with ettnety: and
perhaps with profit. ern
Mode of washing and searching the Matrix.—The mini of
washing and searching is the same in all the mines, the rocky
matrix alone requiring to be broken; it is first thrown into a
trench with water and shoveled and trod like mortar, and as
the object is to wash away the clay, fresh water is thrown on
and poured off repeatedly until the fragments are sufficiently
cleansed, and, as a final purification, they are sifted on fine
baskets, which completes the operation of washing; they are
then spread in a thin layer’ on a smooth floor plastered with —
clay or cow-dung, and when dry the whole is passed under
the hand, and searched three several sata fete which; the:
fragments are thrown aside. |
Reproduction of the Diamond.—The circumstance of dia-
monds being frequently found amongst these fragments after
they have been thrown aside, has, perhaps, given rise to the

Panna in Bundelkhand. 159

idea of their reproduction, and I was anxious to obtain the
opinion of experienced natives on this subject: they admit it
only in one instance, viz. at Majgoha, and even there, it is al-
ways ascribed to the spiritual agency of the founder of the
Mehdivi sect, to whom those mines belong, but their more ra-
tional opinion is as follows, which I will give as nearly as pos-
sible in the words of my communicant :—“‘ The object of
washing is to free the rocky fragments from clay, and particu-
larly to cleanse the diamond, so that it may readily be distin-
guished in the operation of searching, but with all our care we
cannot always succeed ; small diamonds frequently retain their
covering, and. thus elude our search in the first scrutiny, nor
can they be discovered afterwards, until the coating which
concealed them is worn away ; hence it happens that diamonds
are found amongst fragments which have been searched and
thrown aside, but it is observable that small diamonds alone
are so found, and that they rarely exceed the weight of half a
troy grain.”

With regard to Majgoha I am inclined to think that the
above opinion applies with great force. ‘The matrix of these
mines contains calcareous matter, and it is no easy attainment
to wash away a calcareous incrustation by using water alone ;
whenever, therefore, such an occurrence takes place, the dia-
mond might not only elude a first search, but a series of
searches, and even for a series of years, until the coating
which enveloped it was worn away.

Description of the Diamonds.—T he lined of the Panna
mines may be classed according to the following arrangement,
usibg native denominations : 1st, Lilwaja, transparent, colour-
less, having no tinge except the azure which is reflected in a
drop of distilled water ; it is so scarce that only one specimen
was to be found in the town of Panna.

2d, Banspati, Motichar, Ghiya, or Maska: these kinds
are common, the first has a greenish tinge, the second is also
greenish, but varies to a pearly cast; the third is yellowish
and of a greasy or resinous lustre, as its name implies ;—the
crystalline form of this class is very distinct, exhibiting fre-
quently the regular octahedron as perfect as if it had been
shaped by an artist, the dodecahedron is also common, and

. *
160 Captain Franklin on the: Diamond Mines of

so is the spheroidal, arising apparently from the convexity of
its faces, and the obtuseness of its edges, the average price of
this class is thirty Srinagari rupees, for diamonds. of one. retti
weight, 35 for two, 40 for three, 45 for four, and 50 for erse'r4
of five retti weight.

3d, Sambarra and Charehara :: these are they which ‘havi
given rise to the belief that the Panna mines produced only table
diamonds; the specimens I saw were quite irregular in their:
crystalline form, appearing as if they had’ been broken by a
violent blow; but they invariably cleave into thin tabular Ja-
mine, and, as they are generally of a good water, and sell for
a low price in comparison with the others, the Panna jewellers
appear to find it more profitable to work them up, by setting
them in rings or other ornaments; their one retti price is
twenty rupees, increasing according to weight as above stated.

4th, Bengala pashmi, Pira and Matta: these. are yellow-
ish green, yellow, and clove brown, and their crystalline form
is multiform, the price of the one reéti gem is fifteen Fe,
increasing as above. |

5ih, Rekatberar: this is the rose-coloured variety, its’ cry-
stalline form is also multiform, it is not esteemed, and its sin-
gle retti price is twelve rupees. fg)

6th, Kala, Garas, or Jalidar: the first is black or very
dark brown, and the second, as its name implies, includes all’
diamonds that are flawed or appear to contain filaments like
a spider’s web: these varieties are here termed Kaffiya, or seum,
but in England they are called bort, and there they are used
in the arts for diamond dust to an extent unknown in this
country, their price varies according to the size of the stones;
but as they seldom, if ever, exceed one retti weight, the worst
kind may be purchased for eight, and the best for ten nee
the retii.

he above list contains the principal names classed- -accord-
ing to their relative value; but there are others, apparently
founded on fancy alone, a recital of which would embarrass
rather than throw light on the subject; the prices also must
be considered variable, a purchaser coming suddenly into the ©
market would as infallibly occasion a rise, as a deficiency of
demand would create a depression ; a purchaser therefore should

Panna in Bundellshand. a.) 161

fix himself on the spot, and make his purchases gradually, by
so. doing, he would at least save the profits which now go to
the merchants of Benares. , .

Revenue of the Mines:—The revenue of the mines is divid-
ed among the Rajas of Panna, Banda, Chircari, and Jatipur,
but by far the largest share belongs to the former. Accord-
ing to my calculation the Panna division amounts to about
26,000 rupees per annum, but according to Raja Pertar Sinh,
who is the efficient manager of the Panna state, it is 30,000
rupees, and as his authority is likely to be nearer the truth
than mine, I do not hesitate to adopt it; this revenue is deriv-
ed from a tax, originally fixed at one-fourth of the value of all
diamonds found in these mines below a certain weight, which,
I believe, was rated at eight rettis, but the tax now levied is
said to exceed this rate, and on diamonds above the eight re¢tz
weight there is no stipulation ; taking therefore the aggregate
of the Banda, Chercari and Jaitpur shares, as equal to a fourth
of the revenue derived by the Raja of Panna, it will not be too
much to suppose that the produce of the mines amounts to
about 120,000 rupees per annum.

I have now detailed with the utmost fidelity all the circum
stances relating to these mines as they occurred to me at the
time I examined them, and have endeavoured to throw into my
narrative as much perspicuity as the subject is capable of;
still, however, the diamond is too important a mineral to be
passed over in a hasty manner, and I trust I shall be excused
if I here indulge in a few general observations.

General Remarks.—1st, It was formerly supposed that dia-
monds were always found at the same level above the sea, and
it still remains to be proved whether or not there is any truth
in the hypothesis, the following barometrical heights are de-
duced from actual observations made by myself.

Kacha Matriz.

Source of the Ranj river near Udesna, - .-1496 feet.
Floor of the mines of Sakeriya and Udesna, 1470 ,,
. Pakka Matriz. euia
Floor of the mines near Panna, . . 1300 feet.
Bed of the Ranj river due east of the above, 1300 ,,.
Top of its cascade near Ranipur, - - 1240 .,,

>. .
NEW SERIES, VOL. Vv. NO I. JULY 1831. L

162 \ Captain Franklin on the\Diamond Mines of

Source of the Bagin river near Urki, . - a 1420 feet.
Floor of the mine of Kamariya be 3 1380. .,5.-
Bed of the Bagin river due south of them, -») ; B80 eae
Floor of the mines of Brijpur, —_ - ‘ (1260. ,,
Bed of the Bagin river exactly opposite, - ., 1250.,,,>
: Matrix swept away. by <h fieee
Top of its Ist cascade, .-. .- £ 1120 feet.
Transported aa dls
Bottom of Ist cascade, ie actin (an : 900 feet.
Bottom of 2d.cascade, . - 7 >a be dla

From this list it would appear that the rock matrix of the
diamond in the Panna mines has been swept away at an eleva-
tion of 1100 feet, and that its lowest position in situ is i
a and 1300 feet above the sea.

2d, The contracted limits of this diamond tract has already
been mentioned as a peculiarly striking circumstance; the
same kind of sandstone as that in which the diamond is found,
extends far beyond those limits, and why does it not contain

diamonds also? to this question I can only reply by the fol-

lowing explanation: on the north, the scarp of the Bindéchal
hills rests as a point d’appui on a low ridge of sienitic granite,
and the plains of Bundelkhand exhibit primitive rocks through-
out—therefore, excepting transported diamonds, none can be
expected in that quarter ; on the south, lias limestone stretches
along the outline of the counterscarp of the second range of
hills—and here again (excepting the diamonds of the counter-
scarp) none are ever found—being perhaps buried by the over-
dying limestone ; on the west, the sandstone becomes thinner,
being often little more than a mere capping; the conglomerate
form is also frequent, but in the diamond tract it is remarkable
that there is no other conglomerate than that which contains
the diamond ;- moreover, black bituminous shale rises to the
surface near the village of Sahigerh, though in the diamond
tract I have never seen it with less than 400 feet of sandstone,
resting upon it; on the east, the sandstone continues pretty
much the same, and I cannot offer any satisfactory reason wh
‘diamonds should not be found east of the Cheyla Nadi, which
at present is considered to be their eastern boundary.

. 8d, I have endeavoured to show that the rocky matrix of
6

a a ee ey oo =

’ Panna in Bundiekhand. 163

the diamond of Panna is situated in sandstone, which I ima-
gine to be the same as the new red sandstone of England ; also,
that, (if the transported diamonds are excepted,) there is at least
400 feet of that rock below the lowest diamond beds; and,
further, that there are strong indications of coal, underlying
the whole mass; how far this may agree with the geological
position of the same description of mines in Southern India,
will best be seen from the following extracts.

“As far as I understand Dr Heyne in his tracts on India,
pages 103-4, the hills which surround the rock mines of Ban-
ganpilli, are composed of slate clay, and his account of them
reminds me much of Panna, he says, ‘¢ they. are straight at
top, and usually level for some extent,” so that even villages
are built on them—he says also, that ‘ the water of the wells
is brackish,” a strong indication of their saliferous nature, and
further, “ that the country about Banganpilli is sandy: and
stony, and that the stones are chiefly conglomerates, composed
of silicious materials.

' With respect to the rock in which the matrix of the dia-
- mond is found, his description is as follows ;—* the solid rock
ef the hills (which, by-the-bye, is not quite destitute of dia-
monds,) is an aggregate, consisting chiefly of a coarse grey
hornstone, with rounded pebbles of the same species, but of a
fine variety of stone, or of jasper, of different colours: at some
depth, this rock becomes ferruginous sandstone; the grains of
which are finely cemented together, and this kind of stone
usually forms the roof of the floor of the mines; the floor is
generally of a reddish brown colour, with shining ‘particles,
and strikes fire with steel ;” again he savs, through the solid
rock the miners must make their wey before they arrive at
the diamond matrix.

~ Dr Voysey’ s account of ‘these mines is, “ that the diamond
matrix,” in its rocky state, is * a sandstone breccia ;” it lies
_ under ** compact sandstone, differing in no respect from that
which is found in the main range, it is composed ofa beauti-
ful mixture of red, and yellow jasper, quartz, chalcedony and
hornstone, of various colours, cemented together by a quartz
paste, it passes into puddingstone composed of roufided peb-
bles of quartz, horristone, &c. cemented by an argillo-calcare-

164 Captain Franklin on the Diamond Mines of

ous earth, of a loose friable texture, in which the diamonds are
most frequently found.” |

The apparent discrepancy im these accounts is not irrecon-
cilable—but Dr Voysey is most: distinct in his description ; he
says that the rock under which the diamond matrix is found,
is compact sandstone, and that it differs in no respect from the —
sandstone of the main range. He did not see the floor, but Dr
Heyne appears to have done so; and, if I understand him
right, the floor is sandstone also, for he says, (page 105,) that
the diamond bed is of the same nature with the rocks both
above and below it, but is distinguished from them by its su-
perior hardness, and that the floor is so hard that it strikes fire
with steel, a peculiarity which equally applies to the Panna
mines.—Dr Voysey arrived at the following conclusions.

lst, That the matrix of the diamond in the mines of Sou-
thern India is the sandstone breccia of the “‘ clay slate forma~
tion.”

2d, That those found in alluvial soil are produced from the.
debris of the above rock, and have been brought thither by
some torrents or deluge, which alone could have transported,
such large masses and pebbles from the parent rock, and that.
no modern or traditional inundation has reached to such an
extent.

3d, That the diamonds found at present in the bed of the
rivers are washed down by the annual rains.

I cordially agree with Dr Voysey in the general result of
his conclusions, because I am satisfied that the same circum~
stances are applicable to the mines of Panna, but I neverthe-
less. differ from him in two points; 1st, I could not trace any .
likelihood of diamonds being washed away by any natural
causes now in operation, such as the annual rains—they are,
in general, too deeply covered with soil, even in their most su-
perficial beds, to admit of this conclusion, and such only as.
might have accidentally laid on the surface could be so trans-
ported. 2d, I cannot agree with his nomenclature with regard
to ** clay slate formation,” because he himself says, that in
using the term clay slate, he does not mean the T'honschieffer
of Werner, which is the only recognizable term for that rock,
according to the Wernerian system, but excepting these two.

4

Panna in Bundlekhand. 165

points, I have found great accordance with his result, and
am happy in having it in my power to express it.

4th, There is another circumstance to which I must advert,
but I do so with diffidence, and under a hope that it will be
considered merely conjectural. Dr Brewster supposes the dia-
mond to have originated like amber, perhaps from the conso-
lidation of vegetable matter, and that it gradually acquired its
crystalline form, by the influence of time and the slow action:
of corpuscular forces: the late Dr Voysey adverted to this
opinion in his account of the diamond mines of Southern In-
dia; and on the occasion of publishing an abstract of that
paper in his Journal of Science, Dr Brewster observed that
he saw no reason to alter his opinion: now, as the rock matrix
of the diamond of Panna appears in some respects, though not.
altogether, to resemble that of Banganpilli, in Southern India,
there would seem to be little chance of my conjecture being
useful, still, however, as every opinion regarding the origin of
this fine mineral is as yet theoretical, I will not withhold what
occurred to me on this subject, though I again repeat that I
offer it with great diffidence.
_ The theory of Sir James Hall on the consolidation of strata
frequently recurred to me when examining the sandstone in |
which the diamond is found ; I thought that I could discern
much in favour of it, and particularly in the gradual changes
of its nature, from the lower to the upper strata; now, if the
principle of this theory is admitted to be correct and applica-
ble universally, it follows of course that it must be applied
here ; and then it may be questioned how the diamond was
preserved, under that degree of heat which must have been
necessary to form its matrix the gritstone ? In answer to this
objection, I suggest, that the circumstance of calc spar, oc-
curring in trap rocks is somewhat analogous, and if it is ad-
mitted that compression under the weight of strata, and a
superincumbent ocean, had the effect of resisting the expan-
sion of its carbonic acid, and constraining it to continue in
combination with’ lime, might not the same principle be rea-
sonably enough applied, to account for the preservation and
detention of the elements of the diamond in the gritstone ? and
again, should it be further shown that crystals, such as those

166 Mr Johnston an the Vanadiate of Lead, ©

with which we are familiar in nature, may be produced by slow’
cooling or other processes according to the above theory, may
we not look to it oe to account for the crystallization of the
gem? As
This conjecture rests upon the truth or fallacy of Sir James’
Hall’s theory, or on a modification of it, and when this theory’
is considered as the result of long and patient experiment, and’
the high reputation of its author is taken into account, it will
require something more than limited observation, or ordinary’
ability, to answer its objections; my part, however, is merely
the suggestion of a traveller, and I therefore conclude my pa~
per by expressing a hope, that this i mv aloe mineral may’ =e
with more able investigation.

}

Art. XIX.—On the Discovery of Vanadium in Scotland, and
on the Vanadiate of Lead, a new Mineral species. By J AMEs,
F. W. Jounston, A. M. &c. &c. Communicated by the,
Author. a

Ir is a remarkable circumstance, and i ll at ils

the wide diffusion of chemical knowledge, and of the progress

of scientific chemistry, that the new metal Vanadiwm has been
discovered in three different countries nearly at. the same time,
and without any communication between the several indivi.
duals by whom it has been observed and detected. First: in
order of time, Professor del Rio, of the School of Mines of
Mexico, detected a new metallic substance in the brown lead.
ore of Zimapan, te which, probably from its forming red salts,
he gave the name of Erythronium.. His results were not pub-
lished, however, M. Collet Descotils, to whom specimens
were transmitted, having pronounced it to. be an impure:chro-
mium. Meantime Professor Sefstrém, of the Schcol of Mines
at Fahlun in Sweden, detected in an ore of iron.a simple me-
tallic body, which he named Vanadium, and of which he an-
nounced some of the properties about the end of the past year.

The metal of del Rio, it now APPA is the same ‘with: that

of Sefstrém.

In the course of. last winter my attention was divsebial toa
mineral from Wanlockhead, which I obtained from Mr Rose

a new minetal species. >” 167

as an arseniate of lead, to some varieties of which: mineral it;
has a strong resemblance. . On analysis, however, it proved:
different; and though I failed in obtaining pure oxide of chro~
mium, yet I suspected at first that it contained a considerable |
quantity of chromic acid. Repeated attempts, however, to ob-:
tain a pure oxide having failed, and many properties manifest-
ing themselves which chromium does not exhibit, I came at
length to the conclusion that it contained a new metallic sub-
stance. This substance I was engaged in examining when the
letter of Berzelius in the Annales de Chimie, came to hand,

and showed me that my new metal was the Vanadium of Sef-
strom: My stock of the mineral was very small, and it was
from a portion of it, weighing only seven grains, that I pres

pared the compounds of Vanadium which I soon after exhibited

to the Royal Society of Edinburgh.

It is a matter of regret that both the prior discoverers should
have distinguished this metal by names so unwieldy. That
of Sefstrém, though less classical, is the more manageable of
the two, yet it is time that the northern fashion of naming
metals after the barbarous deities of their forefathers should
be exploded.

The Vanadiate of lead, or minhrale containing the metal. in
combination with lead, I have met with in two forms penne
very much from each other.

I.—The more common has much resemblance. externally
to some arseniates—approaches also in colour to that of some
phosphates, and molybdates of lead. It,is opaque, varying in _
colour from a straw yellow to a reddish-brown, and is gene-
rally dull, though in one beautiful wax-yellow specimen it has
very considerable lustre. The lustre of fractured surfaces is
resinous. It is scratched by the knife, giving,a white streak ;
is brittle, and has a conchoidal fracture. The specific gravity
in two specimens was 6.99, and 7-23 respectively. ,

It occurs most abundantly in small mamillz, from a minute
microscopic size to that of a large pin head, sprinkled-over a
surface of calamine. . Occasionally it forms a thin coating upon
thecalamine. In the finer specimens the individualsare larger,
and exhibit groups of six-sided prisms, disposed sometimes in
a dendritical form, but more commonly in rounded pisiform

168 Mr Johnston on the Vanadiate of Lead, &e..

masses, in which the crystalline forms are more or less distinet
and which appear to -be only a-developement of the minute
mamillee. Isolated and perfect crystals are rare. °°

' Heated to redness in a platinum crucible it decrepitates and
assumes an orange red colour, changing when it cools to @
beautiful pale yellow. Before the blow-pipe in a pair of forceps
it fuses, and on cooling retains its yellow colour. If kept some
time in fusion, however, it is changed into a steel grey porous
mass, which upon charcoal gives immediately globules of lead.
Alone on charcoal it fuses readily, exhales the odour of arsenic,
gives globules of lead, and leaves after heating in the inner
flame a steel grey very fusible slag, which exhibits the reactions
of chromium. The fusibility is characteristic of Vanadium. |

The sulphuric and muriatic acids decompose the mineral,
giving green solutions of the oxide, and forming sulphate or
chloride of lead. With nitric acid it forms a beautiful yellow
solution. When the latter acid acts upon it, the oxide of lead
is first dissolved, leaving the fragments covered with a beauti-
ful red coating of the Vanadic acid, which separates occasion-
ally in the form of scales, and is afterwards taken into solutions

II.—'The second form of this mineral can hardly be dis-
tinguished in external characters from earthy porous peroxide
of manganese. It occurs amorphous and in small rounded
forms, often powdering the calamine with a thin black coating,
and at times scattered about in the cavities. It is steel grey, and
porous, as if it had been subjected to heat. Before the blow-
pipe it exhibits the same phenomena as the former variety.

This mineral has hitherto been found only in one mine at.
Wanlockhead, and only in one spot about six fathoms in length,
where the vein had been subjected to a violent disruption. The
mine has been unwrought for the last five or six years, and
the only specimens.to be met with are among the rubbish of
the old workings. A supply of these specimens may be ob~
tained from Mr Rose, mineral-dealer, South Bridge.

I have not yet been able to satisfy myself as to the precise
composition of these minerals. I hoped to have given a correct
analysis in the present, but want of time obliges me to defer it
toa future number.

PorroBe.Lo, 10th June 1831.

Mr Lister’ on the achromatic compound Microscope. 169

Anr. XX:—On. some properties in Achromatic Object-glasses
applicable to the improvement of the Microscope. By Jo-
sEPH JACKSON LisTER, Esq. :

"Te improvement of the achromatic compound microscope
having been an occasional object of my leisure for several years
past, my attention has in consequence been attracted to’ some
properties of object-glasses of short focus and large aperture,
which, so far as I am aware, have not been before noticed, and

which, I flatter myself, may be applied to increase its powers

and the ease of its manufacture.

In offering these, accompanied by some other miscellaneous
remarks, it may be explanatory to introduce them by a short
notice of the several achromatic object-glasses for the micro-
scope which have originated apparently independent of each
other within a few years past.

The first produced in England were the triple ones con-
structed in 1824 and 1825 by Tulley, who had been incited
to the undertaking by Dr Goring: of these an account is al-
ready before the public. 'Tulley has since adopted for his
triple object-glass to be used singly the focal length of 0.9 inch,
applying another of not quite 0.5 inch focus before it when
high magnifying power is required ; and he obtains with these

an image of great sharpness and perfection. His first glasses:

have all the merit of a new invention, having been executed
without the knowledge that anything of the kind previously

~

existed, though other achromatic glasses had before been made.

in France by Selligue, by Fraunhofer at Munich, and by
Amici at Modena.

The glasses of Selligue’s microscope, of which a report was
made by M. Fresnel to the Royal Academy of Sciences in
1824, were composed of a plano-concave lens of flint-glass, and
a double convex of crown or plate, with their inner curves ce-
mented together. Four of these, of from 1$ to 12 inch each
in focal length, were made to screw before each other, so as to
be used together or alone in the manner long practised with
single lenses.

The chromatic aberration was thus in a considerable degree

“

170 Mr Lister on the improvement of the

corrected, but the glasses were fixed in their cells with the con-
vex side foremost, which is their worst position ; and the sphe>
rical error was in consequence enormous, showing’ itself even
through the contracted opening, to which it was necessary ‘on
that account to limit them. | es

Yet, inferior as was the instrument of pllinue. the happy,
idea of combining. achromatic object-glasses, now generally.
adopted, and to which their present superiority is owing, seems
to have occurred to no one else till put in practice by him ; and
the very simple structure of his glasses will be shortly seen not.
to be incompatible with the finest microscopic vision. =,

Chevalier of Paris having manufactured some of these in-
struments, appears to have observed the great error in the po,
sition of Selligue’s glasses ; he retained their construction, but -
turned their plane sides foremost ; and making them of shorter
focal length, and more correctly achromatic, produced in 1825
a microscope far superior to the former. His deepest glasses
are not more than 0.4 inch in focal length, and two of these
were united in his earlier instruments for his highest power ;
but this was the only combination retained in them, and all his
glasses were restricted to apertures too small to show difficuit
test objects.

He has since increased the number of his glasses to be used ~
together, and otherwise improved their performance ;. but if I
may judge from microscopes of his which I have receutly seen in
this country, he does not yet derive from the construction that —
_he has adopted, all the advantage which it may afford.

I am unacquainted. with the date of the first production of -
Fraunhofer’s glasses; they resemble the French in having
their flint lens plano-concave, but they are not cemented, and
the inner surfaces are not in contact, each object-glass being
adapted by the curves of its convex lens for being used alone.
My friend Mr Brown has kindly lent me a series of five glasses
of this description, purchased by him at Munich afew months
ago from the establishment of Utzschneider and . Fraunhofer,
which range from 1.8 to 0.43 inch in focal length, and are of
excellent workmanship: they screw before one another in the
manner of Selligue’s. It appears from an- account of the mi-°
croscope of those artists, printed in 1829, that-it is only lately

achromatic compound Microscope. 17

the glasses have been combined together, and that of the short-
est focus added to the former series of four: and also that:
they are intended to be used in the order of their focal lengths,
_ the shorter towards the object. Each of these glasses singly
admits but a small pencil of from 8° to 15° of light, and when:
so used, their defining power is necessarily not very great;:
but their gombinations have much more, and the different ef-
fects of these will be again adverted to.

The eminent professor of Modena, besides inventing his:
well-known reflecting microscope, was engaged about the year!
1815 with achromatic object-glasses ; but as they did not equal:
his reflector, he laid the work aside, till he was induced to re-:
sume it in 1824, from reading the report already mentioned:
on the microscope of Selligue : from this Amici took the thought
of combining his object-glasses, and pursued it with great suc~
eess, making them double, with the curves of the two lenses of:
each planned for the place it is to occupy, and for obtaining a
good image either with the back glass alone, or with a second
or a third im front.

He brought with him, when he visited London in 1827,
some glasses of this description of very fine performance ;' and!
I have been informed by him that he has since executed a
combination of *¢ 2.7 lines in focal length and 2.7 lines in aper-
ture,” which considerably excels them. ‘

‘The glasses which have been enumerated possess very differ-
ent degrees of merit, chiefly dependent on the extent to whichi
they are divested of chromatic and spherical aberration, and
particularly, in connection with this, on the focal angle of their
aperture; for it has been well established, that a large pencil
from the object is absolutely essential to that brilliancy and:
distinctness of image which characterize a fine achromatic.

When the rays received by the most perfect object-glass
from any indefinitely small bright portion of an object in the
centre of its field are brought together at its conjugate focus,
the image formed by them, though it appears a sharply defined
point if moderately magnified, is really a spot or small circle,
and will show as such if the microscope is sufficiently over-
charged with power in the eye-glass. These circles bear a.con-
siderable analogy to the spurious disks of stars; and like them

172 Mr Lister on the improvement of the

they will be found to be much enlarged by diminiehiaay the
aperture of the object-glass.

They are enlarged also, without contracting the on sieaial
the glass, by increasing the intensity of the illumination, where-
as by darkening the object beyond a certain point they may
be rendered ill defined, and be at length dissolved.

These peculiarities are most observable on some opaque pes

jects, (the reflection from a very small microscopic globule of
quicksilver offers perhaps the best example,) but the same ef-
fects are produced on the light received from transparent ones ;
and the consequent blunting and mingling together of their
minute details when the object-glass admits but a small pen-
cil of light, gives rise to various fallacious appearances. One
of the most remarkable is the spottiness which some surfaces

assume, not unfrequently so much resembling smail globules

as to have been mistaken for them; an optical illusion having
thus been the basis of some ingenious speculations on organic
matter.

tics, the large angle of whose pencil and its accurate correc-
tion enable us to magnify their image greatly, still discovering
something new in our objects, before we are checked by the

circles of diffusion of the effective rays; but these at last, whe-.

ther proceeding from the causes mentioned or from others to
be hereafter noticed, form in every microscope the boundary

to defining power, except where faulty materials or workman-.

ship give it an earlier limit.

It is the marginal rays which contribute especially to ren-
der visible close and delicate lines, such as those on the scales
of lepidopterous insects, and some of the most difficult of these
are even best seen when the central light is blag 9
Note A.)

A glass that is far from correct in its figure will sometimes
show lines of this description sharply, while the outline of the
scale is indistinct, and the contrary; but one in which both
aberrations are destroyed should give the outline and. the lines
distinct together. Even, some good glasses, however, have a
defect, against which we should be on our guard ; thats in cer-

Such appearances have little place with the finer achendiins

je

achromatic compound Microscope. 173

tain directions of the light they are liable to show lines on an
object which do not really exist.

It is observable, that, provided the aperture of the glass
remains open, the central pencil of light admitted behind many
transparent objects may be limited to a very small one with-
out greatly impairing their sharpness ; parallel lines or spots
spread closely over a flat surface, often remaining plainly visi-
ble in this case, which at a far less amount of contraction by a
stop behind the object-glass cannot by any management be
made to appear. The reason of this seems to be, that both
reflection and refraction of a part of the rays take place at such
objects, by which the pencil is spread out on leaving them to
a much increased angle in its progress to the glass.

The relation between the aperture of microscopic object-
glasses, even of the same focal length, and the pencil of light
admitted by them, will vary much, according to differences in
their thickness, their combination, &c. ; and as aperture is va-
luable only in proportion to the pencil it admits, the latter
would seem to be the circumstance the more deserving atten-
tion of the two. It is so often erroneously estimated, that I
will mention a simple mode of ascertaining it, which will be
found pretty accurate. |

Fix a piece of paper on a table, and on it place the micro-
scope with its body horizontal, and one of the eye-pieces on ;
set a candle on a level with it a few yards distant; then
having directed the body of the instrument so far on one side
of the candle, as that the light from it shall bisect the field
vertically, leaving half of it dark, trace on the paper a line
corresponding to the side of one of the legs. Now, taking the
focus of the object-glass as a pivot, turn the microscope hori-
zontally to the other side of the candle, till the opposite half
of the field only is illuminated, and mark again on the paper
the position of the side of the leg. ‘The measure of the angle
traversed, shown by the two lines, is that of the pencil of light,

In the remarks which follow, the term correction is used to
imply the effect preduced by the denser concave lens of a com-
pound object-glass upon the aberration of its convex. Thus,
as in a simple convex lens, the rays which pass through it near
the circumference, have their foci shorter than the more cen-

174 Mr Lister on ‘the improvement of the

tral rays, and the colours of the violet side of the spectrum
into which each ray is refracted have also their foci shorter than
those of the red side ; if ¢ither of these errors is but partially
removed by the concave lens, the glass is said to be under-cor-
rected as to that aberration, and ovEr-conepten if the opposite
error is produced by it.

__A large focal pencil free from.all aberration is evidently the
great requisite for the object-glass of the compound microscope ;
a second point desirable to be attained is, that the field should
be flat and well defined throughout ; and a third, that the light
admitted should as much as possible be only such as goes to
form the picture, and should not be intercepted or ‘diffused
over the field by too many reflections.

. The prominent obstacle to obtaining a sufficient pencil for
high powers by one object-glass of large aperture and deep
curves, is that the correction for the spherical figure by the
concave lens is greater for the rays of the circumference than
its due proportion to that for the more central ones; so that
when such a glass is corrected for the mean of the pencil, if we
suppose its disk divided into a central space and three rings
surrounding it, the rays which pass through the central space,
and those of the second ring from it, will arrive at their focus
when those of the first ring will have just crossed the axis, and
those of the marginal ring will not quite have reached it, The
injury resulting to the defining power is in similar glasses in-
versely as the squares of their focal lengths, as far as regards
this cause of error, as well as those which arise from incorrigi-
ble colour and defects of workmanship. The effects upon the
pencil which have been before described, must not be included
under the same law. This excess of correction in the marginal
rays increases after a certain point so rapidly with a small en-
largement of the aperture of the glass, as soon to prescribe a
limit, beyond which it cannot be carried without injury to the —
picture. :

With Bebe of more contracted aperture, and at the seve-
ral surfaces of which the marginal refraction is moderate, the
effect alluded to is comparatively inconsiderable ; and conse-
quently, by dividing the refraction among two or more such
glasses corrected for the rays that pass through them, the pen-

~~ te. -

PPh Gee Oe ee

4
:
3
S
7
on

. achromatic compound Microscope. 175

cil received may. be enlarged without impediment, and the

light and distinctness greatly increased, thus constituting the
important advantage of combination.

The triple object-glass is thus very superior to a double one
when each is used singly, and the union of two triple ones has
been already proved in England to be eminently effective.

‘Tulley’s 0.9 inch glass singly admits a pencil of near 20°, and

his combination, one of 38°.
_ These triple glasses and the double ones of Professor Amici
are adapted by the form of their curves each to its respective

place; but the foreign double glasses which have their flint

lens plano-concave, and particularly those of Utzschneider be-

fore-mentioned, are made much on one model, and intended to

be each good alone. It might seem but reasonable to infer

from this, that they would be unfit to be combined : and ac-
cordingly when screwed together, most of the numerous prac-
ticable changes of his series of five glasses, of which as many
as four may be united for use, have much indistinctness from

spherical error; and this is I think the case with all, those
combinations which the maker contemplated. Some peculia-
ities, however, observed two years ago in Chevalier’s object-
glasses, led me to undertake a close examination of these, which
.were liberally placed at my disposal for the purpose, in the

hope of discovering the cause for a discrepancy which appear-

_ed in their effects.
I found that with a part of the combinations, the image of

any bright point that was at some distance from the centre of

the field had a faint light or coma stretching outwards from it ;
with others the coma was as much inwards.

The spherical aberration was in general much over. corrected,
but in some triple and quadruple combinations the opposite
error showed itself ; and out.of the whole number one triple
‘and one quadruple were remarkably beautiful and distinct.
The result of this investigation was to disclose or confirm to
me the existence of some properties of the double object-glass,
which have not I believe been hitherto recorded, and which it
is now My purpose to describe only in connection with the sub-
ject before us,—the improvement of the microscope.

With this in view I would premise, that the plano-concave

176 Mr Lister on the improvement of the

form for the correcting flint lens, which was .probably adopt-
ed at first for its simplicity, has‘in that quality a strong re-
commendation ; particularly as it obviates the danger of error
‘which otherwise exists in centering the two curves, and there-
by admits of correct workmanship for a shorter focus. To
cement together also the two lenses of the glass, diminishes by
very nearly half, the loss of light from reflection, which is con-
siderable at the numerous surfaces of a combination. I have
thought the clearness of the field and brightness of the picture
evidently increased by doing this ; it prevents any dewiness or
vegetation from forming on the inner surfaces; and I ‘see no
disadvantage to be anticipated from it, if they are of identical
‘curves and pressed closely together, and + ay cementing medi-
‘um permanently homogeneous. —- gh se

These two conditions then, that the flint lens shall be plano-
concave, and that it shall be joined by some cement to the con-
vex, seem desirable to be taken as a basis for the microscopic
object-giass, provided they can be reconciled with the destruc-
tion of the spherical and chromatic aberrations’ of a large
pencil.

Now, in every such glass that has been tried by me, which
‘has had its correcting lens of either Swiss or English fint-glass,
with a double convex of plate, and has been made achromatic
by the form given to the outer curve of the convex, the pro-
portion has been such between the refractive and dispersive
powers of its lenses, that its figure has been correct for rays
issuing from some point in its axis not far from its principal
focus on its plane side, and either tending to a conjugate focus
within the tube of a microscope, or emerging nearly parallel.

Lab, Fig. 4, be supposed such an object-glass, and let it be
roughly considered as a plano-convex lens, with a curve a.cb
running through it, at which the spherical and chromatic errors
are corrected, which are generated at the two outer surfaces;
and let the glass be thus free from aberration for rays f d eg
issuing from the radiant point f 3 he being a perpendicular to
the convex surface, and id to the plane one. Under these
circumstances, the angle of emergence ge h much exceeds
that of incidence f di, being probably almost three times as
great.

‘achromatic compound Microscope. 177

If the radiant is now made to approach the glass so that the
course of the ray f deg shall be more divergent from the axis,
as the angles of incidence and emergence become more nearly
equal to each other, the spherical aberration produced by the
two will be found to bear a less proportion to the opposing er-
ror of the single correcting curve a c 6; for such a focus there-
fore the rays will be over-corrected.

But if f still approaches the glass, the angle of incidence
continues to increase with the increasing divergence of the ray,
ti]l it will exceed that of emergence, which has in the mean-
~ while been diminishing, and at length the spherical error pro-
duced by them will recover its original proportion to the op-
posite error of the curve of correction. When f has reached
this point f”, (at which the angle of incidence does not ex-
ceed that of emergence so much as it had at first come short of
‘it,) the rays again pass the glass free from spherical aberration.

If f be carried from hence towards the glass, or outwards
from its original place, the angle of incidence in the former
case, or of emergence in the latter, becomes disproportionately
effective; and either way the aberration exceeds the correction.

These facts have been established by careful experiment ;
they accord with every appearance in such combinations of the
plano-convex glasses as have come under my notice, and may
I believe be extended to this rule ;—that in general an achro-
matic object-glass, of which the inner surfaces are in contact,
or nearly so, will have on one side of it two foci in its axis, for
the rays proceeding from which it will be truly corrected at a
moderate aperture ; that for the space between these two points,
its spherical aberration will be over-corrected, and beyond
them either way under-corrected.

I am not aware that an exception is to be made for any
quality of glass or curves that are likely to be used for the
microscope: but I apprehend a case may occur, if the flint
glass is convexo-concave and the convex lens united to its

concave side, that neither of the aplantic pencils may. con-
verge after traversing the glass, and that their foci for a
radiant may be on opposite sides of it, the principle how-
ever of the two foci remaining unaltered. See Fig. 5.

To try this principle under a great change of circumstances,

NEW SERIES, VOL. V. NO. I. JuLY 1831. M

ohh
178 Mr Lister Gn ‘the:improvement of the

and to prove in what manner it was applicable to another most

simple ‘form of the object-glass, having made a. magnified
tracing of the curves of one of Uteschneider’s, and drawn a ray

through it from its longer aplanatic focus, which was ascertained’

after cementing the lenses; I laid down a figure of the’ flint’

lens inverted, shd by. means of the: angles of the other diagram

projected a plano-convex x, Fig. 5, to be joined to its flat side.

The new glass proved as achromatic as the original, though the’

single radius of the plano-convex was’ more than one-third

longer than corresponded with the curves of the former’ dou-

ble convex lens: the-two aplanatic foci showed themselves as’
before ; the longer, however, not in the place indicated by the

ray drawn: but at a point F, about two-thirds more ‘distant

from the glass, and from which both surfaces of. the flint lens

bent the pencil outwards ; the shorter focus F” too: becoming
_ about half the length of the other, and the angle of or,
of its rays not equalling that of their emergence...
The longer aplantic focus may be found when one of the
plano-convex object-glasses is placed in a microscope, by short=
enihg the tube if the glass shows over-correction, if under-cor-
rection by lengthening it, or by bringing the rays together
should they be parallel or divergent, by a very small good tele

scope: The shorter focus is got at by sliding the glass before ©

another of sufficient length and large aperture that is finely

‘ corrected, and bringing it forwards till it gives the’reflexion of —

a bright point from a globule of quicksilver, sharp and free
from mist, when the distance can be taken wpe the glass
and the object. , ts Cyeitne

The longer focus is the place at which to ascertain the ut-
most aperture that may be given to the glass, and where, in
the absence of spherical error, its exact state of correction as
to colour is seen most distinctly. | ieog

The correction of the chromatic aberration, like: that of the
spherical, tends to excess in the marginal rays; so that if a
glass, which is achromatic with .a moderate aperture, has its
cell opened wider, the circle of rays.thus added to the a.
will be rather over-corrected as to colour. |

‘The same tendency to over-correction is oli ‘if, ibith-
out varying the aperture, the divergence of the incident rays

athromntic compound Microscope. | 179.

is much augmented ;-as in an’ object-glass- placed in front of
another: but, generally, in this position: a part only of its.
aperture:comes:into use; so that the two properties mention-
ed neutralize each other, and its chromatic state remains unal-
tered. If, for example, the outstanding colours were observ-
ed at the longer focus to be green and claret, which show that
the nearest practicable approach is made to the union of the
spectrum, they usually continue nearly the same for the whole
‘space between the foci, and for some distance beyond them
either way.

The places of these two foci and their proportions to dati
other, depend on a variety of. circumstances.. In several ob-
ject-glasses that I have had made for trial,—plano-convex,
with their inner surfaces cemented, their diameters the radius
of the flint lens, and their colour pretty well corrected—those
composed of dense flint and light plate have had the rays from
the longer focus emerging nearly parallel; and this focus
has been not quite three times the distance of the shorter from
the glass :. with English flint the rays have had more conver-
gence, and the shorter focus has borne a rather less propor-.
tion to the longer.

_ Tf the-inner surfaces are not cemented, a striking effect is
rodeted by minute differences in their curves. It may give,
some idea of this, that in a glass of which.almost the whole
disk was covered with colour from contact of the lenses, the.
addition of a film of varnish so thin that this colour was not;
destroyed by it, caused a sensible change in the spherical cor-,
rection. :

_ I have found that whatever extended the longer aplantic.
fone and increased the convergence of its rays, diminished
the relative length of the shorter. Thus by turning to the.
concave lens the flatter instead of the deeper side of a convex
lens, whose radii were to each other as 31 to 35, the pencil of
the longer aplanatic focus, from being greatly divergent, was
brought to converge at a very small distance behind the glass ;
and the length of the shorter focus which had been one-half
that of the longer, became but one-sixth of it.

The directionof the aplanatic pencils appears to be scarce-

~

180 Proposed Scientific Meeting at York.

ly affected by differences in the thickness of glasses, if their
state as to colour is the same.
One other property of the double object-glass remains to

be mentioned ; which is, that when the longer aplanatic focus —

is used, the marginal rays of a pencil not coincident with the
axis of the glass are distorted, so that a coma is thrown out-

wards; while the contrary effect. of a coma directed towards .

the centre of the field is produced by the rays from the shorter
focus. These peculiarities of the coma seem inseparable at-

tendants on the two foci, and are as conspicuous in the achro-

matic meniscus, as in the plano-convex object-glass.
(To. be concluded in next Number.)

an

Art. XXI.—WNotice respecting the proposed Scientific Meet-
ing at York on Monday the 26th of September.

Some months ago it occurred to the Editor of this work that

the general interests of science might be greatly promoted by —

the establishment of a Society of British Cultivators of Science,
which should meet annually in some central town in England.

He accordingly corresponded on the subject with several influen-

tial individuals, and found that there was a general desire for the
organization of such a society. As York possessed peculiar ad-
vantages for the first place of meeting, from its local position in

\

reference to the three capitals of the kingdom,—from its having a

Philosophical Society, containing many distinguished members,—

and from its having a museum and other apartments, suited for
the meetings of the society, he addressed himself to Mr Phillips,
the Secretary to the Yorkshire Philosophical Society, in order to

ascertain how such a meeting would be viewed by that society

and by the principal authorities in York. Mr Phillips lost no
time in obtaining the desired information ; and having made ap-

plication to the Mayor of York, (the Right Honourable Lord’
Dundas, we believe,) he was able to report that the authorities

of York entered heartily into the plan, and that the Philoso-
phical Society would willingly charge themselves with any pre-
liminary arrangements which might be necessary.

Upon receiving Mr Phillips’s letter, I transmitted it to John

Robison, Esq. who had kindly agreed to act as interim secretary,

Proposed Scientific Meeting at York. 181

“and who, with the assistance of J. F. W. Johnston, Esq. who
attended the last meeting of German Naturalists at Hamburg,
proposed to draw up a set of regulations or laws to be submitted
to the society at its first meeting.

Under these circumstances, I drew up the notice of the meet-:
ing, which was published in the last number of this Journal,
and which has been widely circulated by the periodical press.

These steps having been taken previous to the dissolution of
Parliament, it was conceived by some individuals, who were ex-
tremely anxious about the success of the plan, that the election
might interfere with the meetings of the society, and that it
might be more prudent to delay its establishment to another
year. As the political agitation of the country has entirely
subsided, there can be no sufficient reason for such a delay, and
it has accordingly been agreed upon to hold the first meeting
of the society at York on Monday the 26th September.

The following Regulations, most of which are adopted by the
German association, are suggested to the consideration of the
Yorkshire Philosophical Society, who ought to be prepared:
with a Code of Laws to be submitted to the Society at their first
meeting. ‘The rules now suggested will be useful in enabling
those gentlemen who mean to attend, and who will be entitled
to act as Members, to transmit (post paid) any observations or
suggestions on this subject, to R. Phillips, Esq. ‘Secretary to the
Philosophical Society, York. :

1. The Society shall be called the Society of the British
Cultivators of Science.

2. The principal objects will be to promote personal inter-
course among scientific individuals, and to adopt every means
for advancing the interests of science in every part of the world,
by promoting scientific inquiries, and procuring assistance to
men of science in the prosecution of their researches.

3. That the Society shall consist of those only who have
written upon scientific subjects, or who have been the zealous:
patrons of science.

4. The. Society shall be managed by a president and a secre-'
tary, resident in the place of meeting for the time being.

_ &. The Society shall meet annually on the and shall
deliberate with open doors.
6. The Society shall hold its meetings at different towns,

182 . Proposed Scientific Meeting at York.

where ‘sufficient accommodation can be obtained, -and the ‘place
of meeting for the next year shall be fixed by the Society be-
fore the termination of its sittings.

7. The Society shall hold no property ; but if books, &e. are
presented to it, they shall be lodged in the museum of the town

where the Society last met.

8. A record of the proceedings of the Socisty: shall be kept
by the secretary.

9. The expences of the Society shall be defrayed. by the con-
tributions of the members present:

The following printed notice is now in circulations and it is
requested that the Editors.of newspapers will have the eer
to give publicity to the views of the Society.

** A strong desire having been expressed that a General Meet-

ing of friends of Science should take place annually in some
central town of England, with the view of promoting unrestrain-
ed communication of scientific opinions and discoveries, a Com-
mittee of the principal Scientific Societies of London, Edinburgh,
&c. have fixed on the City. of York as a most desirable place
for the FIRST MEETING ;—to commence on Monday the 26th of
September, a period of the year which has been ascertained to be
most convenient for the parties interested, the Meeting to be
continued during as many days as may be deemed expedient.
- * Any friends of Science in Great Britain or in other parts of
Europe, who may wish to attend this Meeting, are requested to
senda letter (post paid) to the Secretary of the Yorkshire
Philosophical Society, York, in order that adequate preparation
and accommodation may be secured. It is proposed that the
visitors shall assemble in the Museum and apartments of the
Yorkshire Philosophical Society, to receive memoirs and com-
munications, and that they shall dine together daily.

“ Persons arriving in York on or before the 26th of September
will on application to the Porter of the Museum receive infor-
mation as to the hours and places of Meeting. :

‘‘ Foreigners who may honour this Meeting with their. pre-
sence will find every accommodation prepared for them.”

Mr Witham’s Observations on Fossil Vegetables. 183

Art. XXII.—Observations on Fossil Vegetables, accompa-
nied by Representations of their Internal Structure as seen
through the Microscope. By Henry. Witruam, Esq. of
Lartington, Fellow of the Geological. Society of London ;
of the Royal and Wernerian Societies of Edinburgh, &c.

Tue following extracts which we make are from a splendid
work which bears the above title, by Mr Witham. © The im-
portance of the volume is not little, as we are furnished by it
“with the ready means of examining the character and internal
structure of plants of different geological epochs, ina mode
hitherto little known to the class of naturalists to whose use.
this volume is chiefly designed.

<< My investigations,” observes Mr Witham, “ have led me
to believe, that plants of the Phanerogamic class are much more
abundant in our coal-fields and mountain limestone groups, than
has generally been supposed. ‘The great opacity and peculiar
mineralogical arrangements of these fossil plants, have present-
ed obstacles to the examination of their intimate structure,
which have induced naturalists to rest contented with the dis-
tinctive characters afforded by their external forms; and in
many instances, these forms are obviously too much altered,
to permit us to refer the objects in question, with perfect satis-
faction, to any natural family. But a method has lately been
discovered, by which the stems or branches may be sliced, and
afterwards reduced to such a degree of thinness as to permit
us to inspect the most minute remains of organic texture. The
unexpected result thus obtained, has enabled me to examine
numerous varieties of structure in fossil plants; and I feel con-
fident, that I should be rendering a service to science, by pre-
senting to the public representations of some of these varieties,
accompanied by others of those recent plants to which they
seem decidedly to approximate.

‘“¢ According to the opinion of those who have most success-
fully cultivated geological botany, the essential character of
the first vegetation of the globe consisted in the great develop-
ment and numerical preponderance of the vascular cryptoga-
mic plants; and the great size of the Ferns, Lycopodiacee,
and Equisetaceze, imbedded in our deposits, authorize us to
presume, that, during that period, circumstances calculated to

184 Mr Witham’s Odservations ‘on Fossil Vegetables:

‘ favour the development of these plants had prevailed in a very
high degree. May we not now go a little farther, and, from the
recent discoveries, suppose that heat and moisture had an equal
effect upon plants of different genera from those of the vaseu-
lar cryptogamic? When we discover stems of fossil plants
thirty, sixty, and even seventy feet long—when each torrent:
by its violence uncovers so many relics of ancient times—nay;_
whenever, by the busy ingenuity of man, the lower as well as
the higher sedimentary desposits are interfered with or dis-
turbed, some previously unobserved fossil is discovered, it is
but fair to conclude that the same causes have equally affect-
ed them.

‘* By the investigations of many of my friends, and by m my
own observations, I am induced (as already noticed) to think
that. plants of the phanerogamic class will be found to occur
in greater abundance in the earlier sedimentary deposits than
was before believed. The day is now arrived, when doubts
and difficulties as to the class and family to which they are to
be referred, must give way under the microscopic examination
of the internal structure of these fossil plants; and I am hap-
py in having it in my power to contribute in some degree to
the elucidation of this interesting subject.”

After these and other prefatory observations, Mr Witham
states the arrangement of his volume, which is, ** lst, To offer
some remarks on the Vegetation of the first. period of the An-.
cient World, that is, from the first deposit of the transition
series to the top of the coal-field ; 2dly, To present an account
of Fossil Vegetables found at Lennel Braes and Allanbank
Mill, in Berwickshire ; 3dly, To exhibit representations of the
organic texture, as discovered by the microscope, of several
fossil plants of the Coal formation, Mountain Limestone group,
and of the Lias, together with corresponding representations
of recent plants, of similar or analogous structure, and compa-
rative views of other fossil and recent vegetables, accompanied
with descriptive references ; and, 4¢h/y, ‘I’o conclude with some
general remarks on the varieties represented and described, and
on the subject of fossil plants in general.”

‘Lhe first and second parts of Mr Witham’s divisions we shall
for the present pass over, not, however, without remarking the -
valuable facts. which they record. The section of the work

_ Mr Witham’s Observations on Fossil Vegetables. 185

more immediately connected with the object of the publication
is the third, in which the skilful author thus unfolds his plan,

“ Hitherto, the attention of geologists has been exclusively
confined to the external forms of fossil plants ; and these forms,
illustrated by reference to living species, and to vegetable
anatomy, have afforded characters by. which numerous species .
and genera may be distinguished with accuracy. . But the sup-
posed destruction of the internal structure of most fossil plants,
and the difficulty of applying the microscope to those which
evidently retain it, have hitherto prevented our becoming. ac-
quainted with the organization of these plants. Many fossil
vegetables are converted into a mass of carbonaceous matter :

_ others are filled with up sand, and other substances, the external

part, or cortex, alone remaining ; but it has been found that
many retain their original structure, the interstices being filled
up by calcareous or siliceous crystallizations. A method has
lately been discovered, by which the organization of the latter
may be satisfactorily examined.”

A number of beautiful plates, amounting to six in number,
then follow, containing ‘‘representations of the internal structure
of Recent and Fossil Plants belonging to the Gymnospermous
Phanerogamic, Monocotyledonous Phanerogamic, and Dico-
tyledonous Phanerogamic Classes. The portions represented
are of very thin slices, viewed by prepeniseet light and: magni.
fied about fifty-five times.

Into the details of description connected with the internal
structures thus described, we are precluded from entering ;
nor, indeed, could we well make them intelligible to our read. .
ers without the aid of Mr Witham’s valuable plates. We shall
therefore hasten to the Jast section, in which the author’s con-
clusions are explained.

‘“* The first general remark which I have to offer respecting
the fossil vegetables figured in the Plates, is, that their con-

centric layers present the same irregularity as those of our re-
cent plants. An inference to be made from this circumstance
is, that the climate which existed at the epochs when these ve-
getables grew, resembled ours in the irregularity of its succes-
sive summers. If, at the present day, a warm and moist sum-
mer produces a broader annual layer of wood, than a cold or
dry one, and if fossil plants exhibit such appearances as we

186 Mr Witham’s Observations on Fossil Vegetables.

refer in recent plants to a diversity of summers, then it is rea-
sonable to suppose that a similar diversicy formerly prevailed.
** The Conifer of the coal-formation and mountain lime-
stone group, have few and slight appearances of the lines by
which the annual layers are separated. The trees of our pre-
sent tropical regions have also few and slight appearances of
these lines. Therefore, at the epochs of these formations, the
changes of season were probably as little abe es as they are
in our tropical regions. Rye
** Again, the condensation obpeived towards the outer mar-
gin of each woody layer of the trees of our cold and temperate
climates, and which is attributed to the increasing cold of the
latter part of the autumnal séason, is decidedly observable in
the Coniferze of the lias; as in Figs. 3, and 4, of the lower part
of Plate IV., and in Figs. 1, 2, and 3, of Plate V.. Therefore,
at the epoch when the trees of the lias grew, there was a cold
season as now. 7 4 ,
‘** Between the monocotyledonous fossil. and recent species
which I have figured, no comparison can be instituted, as they
are not of the same species ; but it may be remarked generally,
that, so far as I have examined these plants, the recent species
have smaller-cells and vessels than the fossil.
‘““'The same remark is to be made of the dicotyledonous
woods.” ak
Mr Witham then remarks, that some of the recent Coniferee
which he has figured, are of climates similar to that in which
the fossil Coniferz are figured ; ‘yet that even here no accurate
comparison can be instituted, as we cannot decide upon the
genera, much less upon the species of the fossil plants ; but that
m general the cells’ or tubes of the latter were in almost every
case much larger than those of the former. ‘‘ Our observa- —
tions, however, on this subject,” adds the author, ‘* are not
sufficiently numerous or correct, to authorize any inferences as
to the comparative vigour of the vegetation of the different
epochs, although they are sufficient, along with other circum-
stances, to render it not improbable that the temperature was —
higher at the cs when the fossil vegetables aver - it
is now.
‘*¢ The general colour of the fossil vegetables, coven shoe
organic texture, which occur in our mountain limestone groups,

/

Mr Witham’s Observations on Fossil Vegetables. 187

_-coal-fields, and lias deposits, is brown, of various tints, more
‘commonly wood-brown, frequently umber, and sometimes grey-
‘ish or blackish-brown. — These fossils are al] more or less cal-
careous, and the veins by which they are frequently intersect-
ed, are generally of calcareous spar. Those fossils, on the con-
trary, which, occurring in the same formations, are destitute
~ “of organic texture, have their interior filled with substances ana-
logous to those of which the strata containing them arecomposed.
_ & Silicified fossils occur more aburidatiily ; in the superior for-
‘mations, and are generally of a lighter colour. ' The calcedonic
monocotyledonous and dicotyledonous fossils of the West In-
‘dies vary in colour from yellowish-white to reddish- brown, or
even bright red, but seldom or never assume tints so dark as
‘those of our inferior deposits.
‘. « With respect to the fossil vegetables of which I nate ‘pre-
sented figures, I may here again remark, that, notwithstanding
‘the want of well-defined concentric layers in those of the coal-
formation and mountain limestone group, no doubt remains
with me as to their being Conifer. Should it be shown, by
future investigations, that recent plants of other classes pre-
sent a similarity of structure, the case will become different ;
but until then, it will remain established that these fossil plants
come nearer to the structure of the Conifers than to that of
any other tribe. As to the fossils of the lias, I presume no
doubt can henceforth remain in the mind of any one who may
compare them with recent Conifere, or be satisfied with the ac-
curacy of my representations.”

Mr Witham concludes his highly interesting work by giv-
ing details of the mode in which he prepares objects for the
microscope, for the process of which he acknowledges being
indebted to Mr Nicol. )

‘* Let a thin slice be cut off from the fossil wood, in a di-
rection perpendicular to the length of its fibres. . The ‘slice
thus obtained must be ground perfectly flat, and then polished.
The polished surface is to be cemented to a piece of plate or
mirror glass, a little larger than itself, and this may be done
by means of Canada balsam. A thin layer of that substance
must be applied to the polished surface of the slice, and also
to one side of the glass. The slice and the glass are now to
be laid on any thin plate of metal, as a common fire-shovel,

188 Mr Witham’s Observations on Fossil Vegetables.

and gradually heated over a slow fire, with a view to concen-
trate the balsam. In performing this operation, it will be re-
quisite to prevent the heat from becoming so great as to throw
the balsam intoa state of ebullition; for, if air-bubbles be once —
formed in it, it will be difficult to remove them, and if they
are not removed, they will prevent the complete adhesion of
the two surfaces when applied to each other. The heat of the
shovel should never become so great that the fingers may not —
be held in contact with it, without inconvenience, for a few se- »
conds. With every precaution, some few air-bubbles will some-
times make their appearance, but these may be removed by a
small piece of wood tapering to a point. “When the balsam is
thought to be sufficiently concentrated, and all air-bubbles com-
pletely removed, the slice and the glass may be taken from the
shovel, and applied to each other. A slight degree of pressure.
will be necessary to expel the superabundant balsam, and this
will be facilitated by gently sliding the one on the other. By
this kind of motion, any air that might have got entangled in
the balsam, when the surfaces were brought into contact, sa
also be removed.

«¢ When the whole is cooled down to the temperature of the
air, and the balsam becomes solid, that part of the balsam ads
hering to the surface of the glass surrounding the slice, should
be removed by the point of a pen-knife; and it may be right
to remark, that, in this operation, it will at once be seen whe- .
ther the balsam has undergone the requisite concentration. If,
for instance, it has entirely lost its sectility, and starts off in
flakes before the knife, it will be found that the slice and the
glass will cohere so firmly, that, in the subsequent grinding,
there will be no risk of their separating from each other. Ifthe
balsam has not been sufficiently concentrated, it will slide be-
fore the knife, and, in that case, the two bodies will not adhere —
with sufficient firmness. A very few trials, however, will en-
able any one to conduct the process with success ; and it may
be right to add, that, if the layer of balsam applied to the two
surfaces be not too thick, its due concentration may be accom-
plished in four or five minutes, provided the application, of the
heat be duly regulated. |

‘ The slice must now be ground down to that degree of
thinness which will permit its structure to be seen by help of a

Mr Witham’s Observations on Fossil Vegetables. 189

microscope. To facilitate this part of the grinding, the lapi- |
dary will find it advantageous to fix the glass in a groove made
in a small piece of wood, of which half inch thick deal will
answer the purpose. ‘The groove in the wood should be a
little less deep than the thickness of the glass, and the wood
itself need not project more than half an inch beyond each side
of the glass.

SA lapidary, by attending to the above directions, will find
no difficulty in reducing any piece of petrified wood to that
degree of thinness wiseent to render its structure visible; and
any one, even without the aid of the mechanism employed by
the lapidary, may accomplish that object by attending to the °
following directions.

_ © The position of the fibres of the wood having been ascer-
tained, let a thin piece be chipped off by a blow of a hammer,
ina direction perpendicular to the length of the fibres. Let
the chip thus obtained be cemented to any small bit.of wood
by common lapidaries’ cement (a compound of | part bees’
wax, | part pitch, 4 parts rosin, 16 parts of a mixture of brick-
dust and whitening,) to enable the operator to hold it firmly
while the grinding is going on. That side of the chip which
approaches nearest to a perpendicular to the length of the fibres,
must be ground flat, by giving it a rapid circular motion with
the hand, on a piece of sheet-lead lying horizontally on a table,
and supplied with a little emery, size No. 1, moistened with
water. When the emery ceases to act, the muddy matter re-
maining may be removed, and a fresh portion of emery appli-
ed; and this must be repeated until the surface of the chip
has become perfectly flat. The sheet of lead must then be re-
moved, and a piece of flat sheet copper substituted, and the
surface of the chip ground as smooth as may be, by flower of
emery, freed from its coarser parts. The surface may then be
polished by friction with crocus or rot-stone, on a transverse
- section of any soft wood.

«‘ When the polishing is finished, the chip must be detached
from the wood to which it was cemented, and the polished sur-
face cemented by Canada balsam to a piece of plate-glass, in
the manner above described, and then ground thin, and Potlaes
ed as before.”

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_ THE
EDINBURGH
JOURNAL OF SCIENCE.

Art. I.— Some Account of James Stirling, F. R. 8. By S. P.
Ricaup, F. R.S. Savilian Professor of Astronomy in the
University of Oxford. Communicated by the Author.

James Sririine was a very eminent mathematician, but hard-
ly any thing seems to be generally known about him; and

Hutton * was able to collect very little more than the record

of his death from the obituary of the Gentleman’s Magazine.

He was not, however, one of those common-place men who
just come into the world “ to look about us and to die ;” a
few additional particulars will therefore not be without an in-

terest in themselves, and, by recalling attention to his memory,

may be the means of our learning more. His family may yet

be resident in his native country, and when they find that his

name is still honoured as it deserves, they may, if they are

able, be induced to give us further information about him.

' He was the third son of Archibald Stirling of St Ninians,

in the county of Stirling. On the 4th of January 1711, he

was admitted a commoner of Balliol College, Oxford, and, on
the 10th of the same month, he became one of Snell’s exhibi-

tioners in that society. At this time he was in the fifteenth
year of his age, and consequently, he must have been born in

1696. The particular day of his birth is not preserved in the

University Registers, from which these dates are taken.

* Pgil. Trans. abr. vol. vi, p. 428.
NEW SERIES, VOL. V. NO. Il. OCTOBER 1831. N

192 = Professor Rigaud’s Account of James Stirling.

On the death of Queen Anne in 1714, there was a very large
portion of the British population which was adverse to the suc-
cession of the Brunswick family ; and the events of 1715 showed
that the attachment to the Stuarts was retained nowhere with
greater force than in Scotland. Young Stirling participated
in the feelings of his countrymen, and was tried at the Oxford
Assizes in the summer of 1716, for treasonable language which
he had used against George the First. The jury brought him
in not guilty ; but he did not clear himself from suspicion, as
there is a letter in the Bodleian Library from Archbishop Wake |
to Dr Charlett, (dated July 28, 1716,) in which he says, oe
have had a full account of what passed at your assizes, from
the sermon at St Mary’s, tothe stop put to the hurra that had
like to have risen in the hall upon the acquittal of Sterlin.
The judge did his part fairly, and the man was acquitted, yet
some were never the more convinced that he was not guilty of
the fact whereof he was accused. I am sorry to hear, if he
were fellow of Balliol, that he is still reported to be a nonjuror,
but more that I doubt some of our Scots exhibitioners, om the
Bishop of Rochester’s foundation, have not taken the oaths. I
shall expect to be very well satisfied of these last that they have
qualified themselves as the law requires, before they shall re-
ceive any more money from Bishop Warner's charity.”

It was probably in consequence of these investigations that
notice was taken in college of his politics; for among Thomas
Hearne’s manuscript memoranda in the Bodleian we find it
said :—“ 1717, March 29. Mr Stirling of Balliol College, one
of those turned out of their scholarships upon account of the
oaths, hath the offer of a professorship i in mathematics in Italy,
which he hath accepted of, and is about going thither. This
eentléman is printing a book in the mathematical way at the
theatre.” Nothing appears from which it can be ascertained
whether: he actually went abroad, or, if he did, where he re-
sided, and how long he staid there ; but the book which Hearne
afludes to must have been the Linew Tertit Ordinis Newto-
nian, which he published at Oxford in 1717. Montucla, by
some mistake, describes it as having been printed at London
in quarto; but it was really a small octavo volume of 128 pages,
with an appendix of 19 more, containing the solution of three

Professor Rigaud’s Account of James Stirling. 198

questions,—the curve of swiftest descent, the properties of the
catenary, and a problem proposed by Liebnitz respecting the
curve which would cut certain hyperbolas at right angles: The
work came out by subscription ; and in an old accouut-book
of the Reverend James Pound, at that time rector of Wansted,
there is an entry of his having paid, “‘ 1716, Oct. 10, by sub-
scription for Mr Stirling’s books, * 5s.” Edmund Stone pub-
lished a paper in the 41st volume Philosophical Transactions,
“< concerning two species of lines of the third order, not men-
tioned by Sir Isaac Newton, nor by Mr Stirling.” Stirling is
said to have been very angry at this statement; and probably
he was not better satisfied with Du Gua, who likewise endea-
voured + to detect some partial omissions in the enumeration.
It must, however, be borne in mind, that he could not have
been above one-and-twenty when he published his book ; and
we need hardly look for a stronger testimony to its real merit,
than the circumstance of its having been reprinted at Paris in
1797. The preface of this second edition speaks of it as
“< eximium opus ...... cujus rarissimi libri alteram editionem
jamdudum geometre desiderabant.” The bookseller intended,
if he met with encouragement, to proceed in the republication
of the scarcer works of distinguished mathematicians; a design
which, in many instances, would have been very desirable to__
have had executed, but which was not likely to be profitable to
those who undertook it. It was, however, no small testimony
of the high opinion entertained of this work, that it should be
selected for the first on which the trial was to be made.

In 1719, Stirling contributed a paper to the 30th volume
of the Philosophical Transactions, entitled Methodus differen-
tialis Newtoniana illustrata. It was written in Latin, and in
the title prefixed to it, he simply calls himself é Coll. Ball.
Being a nonjuror, he of course never graduated. He after-
wards published a more extensive work on the same subject,
in his Methodus differentialis sive tractatus de Summatione et
interpolatione Serierum. 'This came out in quarto, and Hutton
says it was “ first published in the year 1730, and again in

* He subscribed for two copies, as appears from the list prefixed to the
book.
+ Montucla, Hist. des Mathematiques, vol. iii. p. 69.

>
194 Pofessor Rigaud’s Account of James Stirling.

1764.” It appears from the sale-catalogue of Dr Hutton’s
library, that he was in possession of both, and it is there-
fore extraordinary that he should have expressed himself so as
to give the false impression of there having been more than
one edition. It was originally printed for Strahan by Bowyer,
although Nichols, in his anecdotes of that great printer, makes
no mention of it. From the scarceness of the copies with 1730
in the title-page, it is fair to conclude that they did not obtain
any extensive circulation ; in 1753, (a date which is still more
scarce, and which is noticed by no writer on bibliography,)
Manby on Ludgate Hill endeavoured to bring the work again

into notice ; and lastly, in 1764, Whiston and White, in Fleet |

Street, became the agents to supply the demand for it. This
last is the date most commonly met with; but any one who
will take the trouble of comparing the books, will find that
there never was more than one edition, the copies of which
have gone out to the world at several times with different title-

pages.

Hutton mentions that an English translation of this mare
by “a Mr Francis Holliday” was published in 1749. Hoolli-.

day printed a collection which he called Syntagma Matheseos,

(8vo, Lond: 1745.) In 1745, he also began a publication, ©

which, was to be continued quarterly, under the title of Mis-
cellanea Curiosa Mathematica, of which he completed one vo-
lume in nine numbers ; he likewise printed five numbers of a
second volume, .and began a sixth, which was never finished.
The work stopped in 1755, possibly in consequence of the
death of E. Cave, the publisher of it, which had taken place

in the preceding year. Holliday was then master of the free |
grammar-school at Haughton Park, near Retford, in Notting- »
hamshire. ‘In 1756, he published an easy introduction to prac-

tical gunnery, or the art of engineering, and in 1777, he print-

ed an introduction to fluxions, having at this time become vi-

car of Markham and Bothamsall 1 in Notts. |
Holliday seems to have paid great attention to Stirling’s

writings. In the Syntagma Matheseos he gave a translation

of the paper on the differential method which had been insert-

ed in the Philosophical T’ransactions, and in the second vo- _—

lume of the Miscellanea Curiosa Mathematica, (p. 162,) he

~ Te —

Professor Rigaud’s Account of James Stirling. 195

says ‘* I shall now annex two problems with their solutions
in summation of series, which. I hope will not displease our
readers, and, when room permits, shall further illustrate Mr
Stirling’s book entitled Swmmation and Interpolation of Infi-
nite Series.” The translation of the whole work was original-
_ly intended for occasional insertion,* by parts, in the same pe-
riodical miscellany, but. Emerson, who had assisted in the re-
vision of it, recommended an entire and separate publication.
It is valuable, not merely from its scarceness, but also from its
forming a comment, in some measure from authority, upon the
original text, as will be seen from the following passages which
occur in the preface. :
** Being unwilling to commit any mistakes that might be in-
jurious to my readers, I had recourse to Mr Stirling himself,
and he was so obliging as to give me all the assistance I need-
ed on this occasion, and particularly his correction and amend-
ment of example 2, + p. 132, concerning which I had some.
suspicion.” ; :
** In a postscript of a letter that I had the honour to re-
ceive from Mr Stirling, dated the 18th of May 1747......, had,
he says, almost forgot to give an answer to that part of your
obliging letter, where you-say that some eminent mathemati-
cians had observed to’ you, that I had nowhere shown from a
given series, how to find the equation of the successive terms :
to which I answer, that the thing is self-evident, or easy in
such series as I proposed to sum or interpole; but in many
kinds of series, the equation to the terms cannot be found, at
least if their relation be considered in the manner I have done.
For this reason, I gave no rule for finding the equations to.
the terms of the series which I considered, and I did not pro-
pose to solve the problem generally, because I knew that it

was not to be done.”
‘In November 1729, Stirling was elected fellow of the Royal

* Upon this plan a translation was begun of Brooke Taylor’s Methodus -
Incrementorum, given with ‘‘a due medium between a paraphrase and a
verbal translation.” It had not, however, proceeded beyond the first ten
propositions when it was stopped by the termination of the publication,

+ Exp. 2. to Prop. xxvi.

196 Professor Rigaud’s Account of James Stirling.

Society, and he afterwards contributed xwo papers to the Phi-

losophical Transactions. The first of them is in the 39th vo-
lume, (for 1735 and 1736;) it treats of the figure of the earth

and the variation of gravity at its surface. His thoughts had

been occupied on this subject for a considerable time, for he
particularly mentioned it in a letter which, in 1733, he wrote
to Bradley, who was his contemporary at Balliol, having en-
tered at that same college not three months after him. The
letter is dated from 'Tower Street, and Bradley’s* answer was
evidently addressed to him in London: some little interval
seems to have elapsed before this answer was written; but
whether he was now fixed in the metropolis, or only on an oc-
casional visit to it, is uncertain. The other paper is contained
in the 48d volume of the Philosophical Transactions, (for
1745,) and gives the description of a machine in which a cur-
rent of air is supplied by the fall of water, so as to blow up
the fire of a furnace.

It is not known that he published any otek works; al-
though he lived to a very advanced age. From the Gentle-
man’s Magazine, (1'770, p. 591,) we learn that he died on the
5th of December 1770, being then agent to the Scotch mining
company in Leadhills. It is probable that he had been con-

nected with that society for many years, or at least there is a —

circumstance ‘that seems to indicate it; for, in his paper on
the blast-furnace, which was to be urged by the means of a
stream of water, he speaks of an engine sufficiently large “ to
smelt harder ore than any in Leadhills.” If the old registers
and account books of the company should be still in existence,
they may enable us to ascertain whether there is any founda-
tion for this conjecture, and may even supply us with some
further particulars of the man, whose talents, no doubt, were
of the greatest service to the establishment.

Oxrorp, July 1831.

* Neither of these letters are as yet before the public ; but they will
appear in the collection of Bradley’s miscellaneous works, which is now in
the press at Oxford.

*
. - 4 .
Se a, a re

De Brewster on a New Analysis of Solar Light. 197

Arr. Il.— On a New Analysis of Solar Light, indicating
three Primary Colours, forming Coincident Spectra of equal
length. By Davin Brewster, LL.D. F.R.SS. Lond. and
Ed. (Abridged from the Transactions of the Royal Society
of Edinburgh. Read 21st March 1831.)

Iw submitting to the scientific world a_new analysis of light,
I am fully aware of the difficulties which I have to encounter.
Even in physical science it is an arduous task to unsettle long
established and deeply-rooted opinions, and that task becomes
Herculean when these opinions are entrenched in national feeling
and assuciated with immortal names. There are cases indeed,
where the simple exhibition of new truths is sufficient to dispel
errors the most deeply cherished. and the most venerable from
their antiquity ; but it is otherwise with doctrines which depend
on a chain of reasoning where every step in the inductive pro-
cess is not rigorously demonstrative; and of this we require
no other proof than is to be found in the history of Newton’s
optical discoveries, and particularly in the opposition which
they experienced from such distinguished men as Dr Hooke
and Mr Huygens.

In the investigations which I am about to explain, the in-
strument employed is the absorbent action which different
bodies exercise on different rays of white light. This principle,
which science had hitherto scarcely recognized, was brought in-
to notice bv the recent discoveries respecting polarization and
double refraction, and was, I believe, first employed as an in-
strument of analysis, in a paper printed in the Edinburgh
Transactions, (vol. ix. p. 433.) In the experiments there de-
scribed, I examined Dr Wollaston’s spectrum of four colours,
viz. red, green, blue, and violet, by means of a purplish-blue
glass. This glass absorbed the blwe rays, which, when mixed
with the yellow, made green, and the yellow rays, which, when
mixed with the red, made orange; and by insulating the yel-
low and red, it thus effected a perfect analysis of the compound
green and the compound orange. From this experiment I drew
the conclusion that yellow light has an independent existence in
the spectrum; and that the prism is incapable of decomposing

: >
198 Dr Brewster on a New Analysis of Solar Light.

that part of the spectrum (of four colours) which it occupies.
_ This unequivocal result of a simple experiment at once saps
the foundation of the prismatic analysis of light. Sir Isaac
Newton, resting on the indications of the prism, concluded that
green and orange were simple colours, and in general, ‘ that
to the same degree of refrangibility ever belonged the same
colour, and to the same colour ever belonged the same degree
of refrangibility ;” but it is now obvious that certain blwe and
yellow rays, and certain red and yellow rays, have the very
same refrangibility, so that, in the same medium, refrangibility
is not a test of colour, nor colour a test of refrangibility.
These views were confirmed by experiments made by Mr
Herschel, and printed in the same volume of the J'ransac-
tions; but, in referring to them five years afterwards, in his
Treatise on Light, he regarded them as liable to formidable
objections. ‘* This idea,” says he (the inability of the prism
to analyze light), ‘‘ has been advocated by Dr Brewster, in a
paper published 1 in the Edinburgh Philosophical Transactions,
vol. xi, and the same conclusion appears to follow from
other experiments published in the same volume of that collec-
tion. According to this doctrine, the spectrum would consist
of at least three distinct spectra of different colours, red, yellow,
-and blue, overlapping each other, and each having a maximum
of intensity at those points where the compound spectrum has
the strongest and brightest tint of that colour. It must be
confessed, however, that this doctrine is not without its ob-
jections ; one of the most formidable of which may be drawn —
from the curious affection of vision occasionaily (and not very
rarely) met with in certain individuals who distinguish only
two colours which, (when carefully questioned and examined,
by presenting to them, not the ordinary compound colours of
painters, but optical tints of known composition), are generally
found to be yellow and blue.”

To these remarks Mr Herschel has added an illustrative ae

figure of the spectrum, in which it is made to consist of Sour
colours, red, yellow, blue, and violet ; the red extending to the
middle of the yellow, the yellow beginning at the extremity of
the orange and terminating at the indigo, the blue beginning
at the middle of the yellow, and terminating at the end of the

Dr Brewster on a New Analysis of Solar Light. 199

violet, and the violet beginning at the indigo, and terminating
at the extremity of the spectrum. :

I have not been able to discover what the general objections
are which Mr Herschel refers to in the preceding passage: but
the formidable one which he distinctly specifies will be found
to have no weight. An obscure physiological fact occurring in
one eye out of a million, could not, on any principle, affect the
result of a legitimate induction ; but even if we invest it with
the character of a general fact, it will be found to be a direct
argument in support of the very views which it was supposed
to contradict.

These views, or the analysis of the spectrum to which they
lead, may be expressed in the following propositions :

1. White light consists of three simple colours, red, yellow,
and dlue, by the mixture of which all other colours are formed.

2. The solar spectrum, whether formed by prisms of trans-
parent bodies, or by grooves in metallic and transparent sur-
faces, consists of three spectra of equal length, beginning and
terminating at the same points, viz. a red spectrum, a yellow
spectrum, and a d/we spectrum.

3. All the colours in the solar spectrum are compound colours,
each of them consisting of red, yellow, and blue light in differ-
ent proportions.

4. A certain quantity of white light, incapable of being de-
composed by the prism, in consequence of all its component
rays having the same refrangibility, exists at every point of the
spectrum, and may, at some covers be exhibited in an insu-

lated state.
_ This remarkable structure of the spectrum will be better

understood from Plate II., where Figs. 1, 2, and 3, represent
the three separate spectra, which is iit in their combined
state in Fig. 4

In all these figures the point M corresponds with the vedi!
or least refrangible extremity of the spectrum, and N with
the violet, or most refrangible extremity; and the ordinates’
ax, bx, cx, of the different curves MRN, MYN, MBN, re-
present the intensity of the red, yellow, and blue ray at aay
point x of the spectrum.

If the distance M z in all these spectra be equal, then, in

200 Dr Brewster on a New Analysis of Solar Light.

the combination of them shown in Fig. 4, the ordinates aa,
bx, ca, will indicate the nature and i intensity of the colons at
any point 2 of the red spectrum. Thus, let

The ordinate for red light ax = 30
yellow be = 16
blue — c= Y

au+ be +cax = 48 rays,

then the point 2 will be illuminated with 48 rays of light, viz,
30 of red, 16 of yellow, and 2 of blue light.

Now, as there must be certain quantities of red and yellow
light, which will form white, when combined with 2 blue rays,
let us assume these, and suppose that white light, whose in-

tensity is 10, will be formed by 3 red, 5 yellow, and 2 blue

rays; hence it follows that the point « is illuminated by

Red rays, 27
Yellow rays, 11
White light, 10

48 rays,

or what is the same thing, the light at a will be orange, ren-
dered brighter by a mixture of white light. The ¢wo blue
rays, therefore, which enter into the composition of the light
at a’, will not communicate any blue tinge to the prevailing
colour.

If the point aw is taken nearer M, and if, at that point, the
blue rays are More numerous in proportion to the yellow than
2 to 5, that is, if they are as 3 to 5, then there will be 1 blue
ray more than what is necessary to make white light with the

2 yellow and the 3 red rays, and this blue ray will give a blue

tinge to that part of the spectrum, or will modify the peculiar
colour of pure red light. In like manner, the blue extremity
of the spectrum may have its peculiar colour modified by an
excess of red rays so as to convert it into violet light. In this
manner the tinge of red light at the blue extremity of the
spectrum, and of blue light at the red extremity, may be ex-
plained, even if the least refrangible branch BM of the blue

=~ ee ee Nee ae

a

Dr Brewster on a New Analysis of Solar Light. 201

curve is every where within the least refrangible branch YM
of the yellow curve, and the most refrangible branch RN of
the red curve every where within the most refrangible branch
YN of the yellow curve. On this supposition the excess of
blue light over the yellow will begin to modify the red space
at that point where the ordinates ca, bz, are in the ratio of 2
to 5; the ratio in which they exist in white light, and the ex-
cess of red light over the yellow, will begin to modify the blue
space at that point where the ordinates of the most refrangible
red, and most refrangible yellow, branch are as 3 to 5, the
ratio in which the corresponding rays exist in white light.
But it is not improbable that the blue branch BM may actu-
ally cross the yellow branch YM at some point m, as shown
in Fig. 5; and the red branch RN the yellow branch YN, so
that the blue ordinates in the one case, and the red ordinates
in the other, will exceed the yellow ordinates at every point
beyond the points of intersection m and n. If this should
prove to be true, it follows, that at and beyond m the red
should, as it were, re-appear, and by its predominance convert
the extreme blue space between n and N into violet.

In every part of a spectrum thus composed, there neces-
sarily exists three different colours, which form'a compound
tint by their union; and as the three differently coloured rays
have at every point the same refrangibility, it is impossible to
separate them, or to analyze the compound tint by prismatic
refraction. By transmitting the compound tint, however,
through transparent solids or fluids, which absorb one or more
of the simple rays, and allowing the rest to pass, we may ex-
hibit one or more of the rays separately, or obtain a residual
colour, which indicates the presence of rays whose existence
cannot be inferred from the original colour of the compound
tint. If, for example, we transmit the compound ray at 2,
Fig. 4, through an absorbing medium, which detains 27 red
rays, we shall obtain a transmitted tint with 11 yellow rays,
and 10 of white light, or a brilliant yellow; and if we again
transmit this light through another medium which absorbs 11
yellow rays, we shall have a pure white light, composed of 3
red, 5 yellow, and 2 blue rays. This white light will exhibit
the singular property of homogeneous light; namely, that of

202 Dr Brewster on a New Analysis of Solar Light.

being indecomposable by the prism, and of being pre-eminent-
ly adapted for the nicest purposes of vision. ‘The existence of
such light has never even been conjectured, and its insulation
at any point of the spectrum becomes a proof of the existence,
at that point, of red; yellow, and blue rays of faual fee
bility. °

Having thus given a general view of the structure abril Ll
_ have found in the spectrum, I shall now proceed to state the
experimental evidence from which it has been deduced.

From the simple inspection of the coloured spaces, it is ob-
vious that red light exists in the red, orange, and violet divi-
sions of the spectrum; but, according to Fraunhofer’s mea-
surements, these three spaces occupy 190 parts when the whole
length of the spectrum is 360; hence, red rays are observed .
in more than one-half of the whole spectrum. If we examine
the blue and indigo spaces through certain yellow fluids, such
as oil of olives, they acquire a distinct violet tint, so that these 7
fluids must have absorbed ‘some rays which had neutralized or —
masked the red. Red light, therefore, exists in the blwe and
indigo spaces ; and, as I shall afterwards show that white light,
which necessarily includes red, may be insulated both in the
green and yellow spaces, it follows that red light exists in all
the seven coloured spaces into which the spectrum is divided.

Yellow light is distinctly recognized by the eye in the orange,
yellow, and green spaces which occupy 77 parts of the spec-
trum whose length is 360. When the spectrum is examined
with a deep blue glass, the green light is distinctly seen at F,
one of Fraunhofer’s lines ; and as a green transparent wafer —
of gelatine produces a whitish band beyond F, and in the blue’
space, it is clear that a certain portion of yellow light must
exist there. We have already seen that the action of oil of olives
on the blue and indigo spaces absorbs certain rays and leaves
a violet tinge. ‘These rays cannot be red, and they are not
blue, because blue taken from blue would not leave violet.
They must, therefore, be a small portion of yellow rays, which,
forming white with the red, and a portion of the blue, had the
effect of diluting the predominant blue light. ‘The existence
of both yellow and red rays in the blue and indigo spaces,
may be inferred from another experiment. When we trans-

Dr Brewster on a New Analysis of Solar Light. 203

_. mit the spectrum through a certain thickness of a blue solu-
tion of the ammonio-sulphate of copper, the blue and indigo |
spaces appear to be much diluted with white light, that is,
the blue appears to be mixed with red and yellow. Now, if
_ this apparently diluted blue light is a pure homogeneous blue,
containing neither red nor yellow rays, it would suffer no more
diminution in passing through an additional thickness of the
ammonio-sulphate, than white light would do in passing
through the same thickness of pure crystal or pure water, that
is, it would suffer no perceptible change. But, in passing
through the copper solution, the blue becomes rapidly deeper
and less white, which can arise only from its absorbing the
red and yellow rays, which cause its apparent whiteness. In
order to apprehend the force of this argument, we must con-
sider, that though a dark red or a dark blue fluid appear
opaque, as they are in reference to white light, of which the one
absorbs all the rays but the red, and the other all but the blue,
yet, in reference to red and blue light, which each of them
freely transmits, they may be regarded as perfectly transpa-
rent. Nothing is more remarkable to those who first make
the experiment, than the imperceptible diminution of intensity
which a beam of homogeneous red light experiences in pas-
sing through a great thickness of a red fluid, particularly when
the original red beam is produced by transmission: through
the same red fluid. It is owing to this cause that the colour
of a wine-glass, full of port wine, is nearly as deep as that of
the wine in the thickest part of a wine decanter.

That yellow light exists in every part of the red space, may
be proved by numerous experiments. By using a prism of
port wine of 90°, or by viewing the spectrum through certain
thicknesses of balsam of sulphur, balsam of Peru, pitch, or red
mica, yellow light can be seen directly at the line marked C
of Fraunhofer, which is far within the red space; and, by
the absorptive action of these four last substances, the whole
of the red space has a yellowish tint, arising from the absorp-.
tion of blue light. The very same effect is produced, but in a
more striking manner, by transmitting the light of the red
space through certain yellow, orange, and green transparent
wafers, all of which absorb some blue light, and leave the whole

204 Dr Brewster on a New Analysis of Solar Light.

of the red space of an orange tint, that is, containing yellow
light. In support of the opinion that there are yellow rays
in every part of the red space, I may adduce a casual experi-
ment of Sir W. Herschel’s, Phil. Transactions, 1800, vol. xe.

p. 255, when he had occasion to view the prismatic spectrum

reflected from clear turned brass. ‘* The colour of the brass,”
says he ‘‘ makes the red rays appear like orange, and the orange
colour is likewise different. from what it ought to be.” From
these observations it follows, that yellow light may be traced
through all the coloured spaces except the violet, where I have
not yet been able to find it; but this is not surprising when
we consider the great faintness of the violet rays, and the faci-
lity with which they are absorbed by media of almost all co-
lours. Even the deep blue ammonio-sulphate absorbs almost
_the whole of the violet space, and the smalt blue glass nearly
one-half of it, so that it is extremely difficult to subject it to
the partial action of absorbent media.

It is obvious, even to the eye, that blwe light exists in the
violet, indigo, blue, and green spaces, which occupy 247 parts
out of 860, or more than two-thirds of the whole spectrum.
When the most refrangible rays are absorbed by certain thick-
nesses of balsam of sulphur, balsam of Peru, pitch, or red mica,
the blue mixed with yellow, and forming green, may be traced
very near the line C of Fraunhofer, which is considerably with-
in the red space. That the blue extends over the whole red
space is proved by the same arguments which we used for yel-

low light; for when the red space is made of an orange tinge

by the absorptive action of certain yellow, orange, and green

media, this change can be effected only by the pei: of

blue light.

Having thus proved that red, yellow, and Dhnie light exist in
almost every part of the spectrum, I shall proceed to corrobo- -
rate these views by showing that white light may be actually —

insulated in different parts ofits

When we look at the spectrum through a particular bitte
glass of a certain thickness, we insulate the yellow space, the
colour of which is. a rich gamboge-yellow. By increasing the
thickness of the glass, this compound yellow acquires the pale
straw-yellow colour of the yellow monochromatic flame pro-

ee ee es

Dr Brewster on a New Analysis of Solar Light. 205

duced by the combustion of alcohol and water, or of an alco-
holic solution of salt. At a still greater thickness of the glass
we produce a greenish-white band, which, by changing the
glass for a different blue, becomes a reddish-white band. If
we now mix a solution of sulphate of copper, which acts upon
the rays on the red side of the yellow space, with diluted red
_ ink, which acts on the rays on the blue side of the same space,
-we shall reduce the rays in the yellow space to nearly white
light, with a slight tinge of green, when there is too much
sulphate of copper, and a slight tinge of red when there is too
much red ink. ‘This insulation of white light may be pretty
well effected by some of the smalt blue glasses acting alone ;
and in some cases the purity of the light may be increased by
a solution of sulphate of copper and iron, or even by a green
glass. The white light thus exhibited may be rendered yel-
low by means of a yellow transparent wafer, which absorbs
some of its blue rays, and green by agreen transparent —_
which absorbs some of its red rays.

From these experiments it follows, that white light, compos-
ed of red, yellow, and blue rays, exist in the most luminous part
of the spectrum, and may be insulated by absorbing the excess
of yellow light, and of any of the other cclours above what is
necessary to compose white light. In applying a highly dis-
persing prism, it was a singular and peculiarly interesting sight
to witness, for the first time, a beam of white light, consisting
of red, yellow, and blue rays of equal refrangibility, and inca-
pable of being analyzed by prismatic refraction.

The preceding observations. contain only a few out of a
great number of experiments which I have made on the ab-
sorptive action of natural and artificial crystals, and of various
- fluids and uncrystallized solids which possess either a natural ©

+ or an artificial colour. I made a few experiments in the course

of this winter with the coloured juices of several hot-house
plants, which Mr Forbes was so good as to prepare for me ;
and I expected, in the course of the summer, to obtain by this
means, a more striking insulation of some of the simple colours,
than I had effected by the substances within my reach. Im-
patient, however, of so long a delay, I thought of supplying,
to a certain degree, the place of these absorbing fluids by a
subsidiary principle of analysis, which, in its practical applica-

206 Prof. Powell on the alleged Polarization of Heat.

tions, exceeded my most sanguine hopes, and has furnished
me with the means, not only of analyzing the colours of na-
tural bodies, but of determining the causes from which these
colours originate. An-account of these, and of other applica-
tions of it, will form the subject of separate communications,
and I shall confine myself at present to the single observation,
that, in applying this method of absorption to the decomposi-
tion of the solar rays, I have been able to insulate white light, .
both in the orange.and in the green space, and thus obtain
the most ample proof of the peculiar analysis of white light
which it has been the object of this paper to establish.

By means of this analysis we are now able to explain the phe-
nomena observed by those who are insensible to particular co-
lours. (See this Journal, No. xix. Old Series, p. 153, and No.
ix. New Series, p. 88.) The eyes of such persons are blind
to red light ; and when we abstract all the red rays from a
spectrum constituted as above described, there will be left two
colours, blue and yellow, the only colours which are recognized
by those who have this defect of vision. To such eyes light
is always seen in the red space, but this arises from the eye
being sensible to the yellow and blue rays which are mati with
the red light.

Hence blue light will be seen in the place of the violet, end
a greenish-yellow will appear in the orange and red spaces, or,
which is the same thing, the spectrum will consist only of the
yellow and the blue spectra shown in Fig. 2 and 3. The phy-
siological fact, and the optical principle, are therefore in per-
fect accordance; and while the latter gives a precise explana-
tion of the former, the former yields to the latter a new wt
an unexpected support.

Art. IIl].—Further Remarks on the alleged Polarization of
Heat. By the Rev. Bapen Power, M. A. F. R/S.
Savilian Professgr of Geometry in the Prone oF on
ford. Ina Letter to Dr Brewsrexr. MES

DEAR mR

In the number of your Journal for July 1830, you’ did me the
favour to insert a’communication on the alleged polarization

Prof. Powell on the alleged Polarization of Heat. 207

of heat, in which I stated, that, as far as I was aware at that
time, M. Berard’s researches on the subject had not been pub-
lished. I have, however, recently been informed that I was
mistaken ; and being referred to the 3d volume of the Mé-
moires de la Societé d Arcueil, (Paris, 1817,) I there found
the paper in question, entitled ‘* Mémoire sur les propriétés
des differentes espécés de rayons qu’on peut s¢parer au moyen
du prisme de la lumiére solaire, par M. J. E. Berard. Lu
a Vinstitut le 21 de Dec. 1812.”

I immediately examined the memoir with reference to the
question discussed in my former communication ; but, I must
confess, felt not a little disappointed at the very slight infor-
mation which the distinguished writer affords as to aha parti-
cular points on which, it appears to me, so much of the force
and importance of the general result depends.

The principal particulars which I can collect as bearing on
my questions are these :

lst, The thermometer employed was an air-thermometer,
containing a bubble of alcohol in the tube.

2d, 'The apparatus, consisting of glasses like Malus’s, had
the axis of revolution placed vertically. No mention is made
of any precautions in regard to the very important point of
guarding against irregular action of heat by screens, &c.

$d, With regard to the radiation from hot metal, the source
was * une boule de cuivre de Ja grosseur d’un ceuf,” which was
placed in the focus of a concave metallic reflector. It was
used in the first instance at a bright red heat, and im this case,
as well as in that of the solar rays, the results agree entirely
with what I have before stated.

4th, The author then proceeds to the case of simple heat —
unaccompanied by light : this he seems to consider but of se-
condary importance, regarding it in connection with the views
inferred from De la Roche’s experiments, but, after a few re-
marks, proceeds thus to describe his experiments :

‘« J’ai attendu dans quelques experiences que la boule de
cuivre ne fut plus visible dans lobscurité ; et je me suis as-
suré que les rayous qu “elle emettait dans ce cas pouvaient étre
aussi polarises.”

This meagre, not to say somewhat ambiguous statement, is

NEW SERIES, VOL. V. NO. If. OCTOBER 18981. o

208 Prof. Powell on the alleged Polarization of Heat.

‘the whole account given of a portion’of the research at once
(according to my view of the matter) the most essentially im-
portant, and certainly the most difficult and delicate to car-
ry on.

Of the nature of the results in general, so long as any light
is present, I have already expressed my opinion, and in these
cases the causes of fallacy do not act in the same proportion ;
but in the case of the simple radiant heat, I think it will be
allowed that a vertical arrangement of the apparatus must leave
the results open to very serious objections, and the adoption of
the air-thermometer will by some be thought still more os
tionable. 2 x

In my former communication, I mentioned that riny Sakopans
ments, made with a mercurial thermometer, though unsatisfac-
tory from the minute effects produced, appeared to confirm
M. Berard’s as to all cases of heat accompanying light, but
that they failed to do so in the case of simple radiant heat.
With the information now before me relative to M. Berard’s
researches, I resolved again to repeat the experiment in the
case of simple heat from metal below visible redness, making
use of an air-thermometer as he had done. I arranged my
apparatus as before, horizontally, the iron ball, two inches
diameter, was placed in the focus of a tin reflector, six inches
diameter, so situated that the rays would fall on the first glass
at the proper angle. The blackened bulb of am air-thermo-
meter was fixed in the focus of the small reflector attached to
the second glass; the adjustment being made by the light of
acandle. The bulb of the thermometer was three-fourths of an
inch in diameter, and the air was confined by a bubble of
coloured liquid in the tube, as in M. Berard’s experiments.
The tube of the apparatus passed through a thick screen, so
that all communication of heat to the thermometer, except
along the tube, was completely intercepted. Every precaution
being duly taken, and the second glass reflector, with the ther-
mometer, being in azimuth 90°, on admitting the radiant heat,
a small effect was produced, and the reflector being then turn-
ed into azimuth 0°, and back again to 90° several times, no
sensible difference could be observed between the —_ im the
respective positions.

Mr Potter on the Aurora Borealis. 209

Such are the results I have been able to obtain, entirely con-
firming my former conclusions. The inquiry is certainly one
of a very troublesome nature, and where it is difficult to feel
perfectly satisfied. The principal obstacle is the want of a
thermometer at once sufficiently sensible and accurate. Those
who are practically conversant with air-thermometers, will pro-
bably be ready to admit that there is much uncertainty attend-_
ing their indications. It is to the improvement of mercurial
thermometers that we must look for the extension of our know-
ledge on this and all questions connected with radiant heat.
To secure at once an instantaneous communication of the ef-
fect, a 1 large range on the scale corresponding to a small degree
of heat, and a pidbfect freedom of motion to the liquid in the
tube, are the desiderata in instruments for these purposes,
whilst the graduation is wholly irrelevant. It is to be hoped
that some of our philosophical artists will direct their attention
to this point.

I cannot conclude without repeating my earnest hope that
these experiments will be tried by others better qualified to do
' justice to them. By the multiplication of observations, we can
alone hope to be able to speak with confidence as to investiga-
tions of so delicate a nature-—I remain, my Dear Sir, very
truly yours,

B. PowEtt,
- Oxrorn, July 24, 1831.

Arr. IV.—On the General Equations for determining the Po-
sitions and Curvatures of Arches of Aurora Boreales, from
observations made in one place only; with Calculations for
that of the 25th December 1830. By R. Porrer Junior,
Esq. Communicated by the Author.

Since writing my former essay on this subject, I have taken
some little pains to learn what has been done by others. In
the beginning of the eighteenth century, the meteor appears
to have occurred very frequently, and attracted the attention
of many scientific men. Amongst these, the celebrated Swe-
dish philosopher Celsius, commencing about the year 1716,

> ‘
210 Mr Potter on the Aurora Borealis.

made observations on 316 aurorse, and wrote a treatise wherein
these observations are recorded; but which I have not yet
met with.

The celebrated Mayer wrote also in the year 1726, pretty
fully on the aurora in the first volume of the Commentarii
Petropolitane ; and I was not a little surprised to find that —
he had proposed a formula for finding the elements of an —
arch from one observation of its altitude and its extent on the
horizon, by considering it as a circle parallel to the equator.
The reader will see that this is similar to the method I have.
proposed, only that he was ignorant of the relation of the
meteor with the earth’s magnetism. When his formula is
adapted to this discovery, we may find the distance of an arch —
by it in the first place, and knowing this, we easily find the
height. The results, as I have proved, are just the same as
by mine. He there gives only the formula without the de-—
monstration; this last was, however, supplied by Maupertuis
in the Histoire de ? Academie Royale des Sciences, for 1732.
Mayer laid his demonstration before the Petersburgh Aca-
demy in 1728, but, as their Transactions were not published
until some years afterwards, Maupertuis does not appear to
have been aware of it.

In the year 1731 Mairan, who had previcnlily written seve-
ral memoirs, published an extensive treatise on the aurora,
which stands as a supplementary part to the Hist. de [Acad.
for that year. He was much occupied with hypothetical
views, that the aurora was caused by the zodiacal light, and
that this latter was no other than the sun’s atmosphere ex-
tending beyond the orbit of the earth. He gives an extensive
catalogue of auroree which had been observed from very early
times, and several very good plates of the different appearance
of the meteor. He enters also very fully on the subject of its
height, and made calculations for several obser vations on the pa-
rallactic or trigonometrical method; and in one case he made
use of the formula of Mayer. He found the height of the
aurora of the 19th October 1726, to be 70 French leagues
above the surface of the earth; but in general his calculations
brought out the height about 200 leagues, some few being as
low as 100, and some as high as 300 leagues. |

Mr Potter on the Aurora Borealis. 211

Soon afterwards the celebrated Dutch philosopher Mus-
chenbroek treated very fully, in his physical essays, on the
aurora. Muschenbroek made many observations, and was, as
far as I have found, the originator of the hypothesis, that the
meteor arises from electrical clouds, and is only at a low ele-
vation. Like his successors in the same view, he preferred
trusting to the capability of his eyes for ascertaining distances
to actual positive measurement. As he says every thing, per-
haps, which can be said in favour of his’ hypothesis, I will
here give an extract of the summary of his arguments from
the French translation of his work by Pierre Massuet, i
lished in 1739. 7

** L” Aurore boréale est dans notre atmosphere, et non pas
dehors ou au-dessus.

** 1°. Parceque qu’elle paroit le soir sous la forme d’un nuage,
qui ne différe pas des ‘autres nuages, que nous volons commu-
nément. Le grand nombre dobservations, que j’ai faites pen-
dant longtems pour découvrir la nature de cette lumiére,
m’ont appris, que ce n’est autre chose qu’un nuage semblable
aux autres qui roulent dans lair, ou ils sont suspendus, et
qu'elle se trouve aussi A la méme hauteur que ces nuages,
autant qu’on peut en juger par la vue. Si on est curieux de
savoir, quelles sont les marques auxquelles on peut connaitre
cette Jumiére pendant le jour, il suffit de faire attention a ce
qui suit. Lorsqu’il doit tonner, on voit Pair couvert de
nuées, qui sont a diverses hauteurs, et peu distant les unes
des autres: on les voit flotter ga et la dans lair, et quelques
unes de leurs parties parvissent blanches, les autres brunes.
Les nuées qui forment laurore boréale, sont suspendus de la
mémes maniére dans l’atmosphere, roulant confusément les
unes sur les autres, de sorte qu’une personne peu accoutumée
4 observer ces phenoménes jugeroit d’abord que la tonnére est
prét a tomber sur sa téte. Mais les aurores boréales sont
moins épaisses, d’un blew tirant sur le cendré, elles flottent
doucement dans lair, et ne s’éléve au-dessus de horizon que
jusqu’a une certaine hauteur. Lorsque tout cela se manifest
au nord, au nord-est, ou au nord-ouest, il paroit surement la
nuit une aurore boréale ; et si cela continue quelques jours et
quelques nuits de suite, on a alors pendant le jour une occa-

212 Mr Potter on the - een Borealis.

sion fort favorable pour faire connaitre ce météore, &c. &e.—
Je crois donc qu’on ne peut douter, que ces aurores boréales
ne soient des nuées repandues dans notre atmosphere.”

«¢ 2°. Comme la nuée lumineuse se tient plusieurs heures de
suites 2 la méme hauteur au-dessus de horizon, elle doit ne- -
cessairement se mouvoir en méme tems que notre atmosphere;
car puisque la terre tourne chaque jour autour son axe, cette
nuée lumineuse devroit paroitre s’élever au-dessus de Phorizon
et descendre au-dessous, si elle se trouvoit au-dessus de Pat-
mosphére. Cette nuée étant donc emportée en méme tems que
notre globe et notre atmosphere, il y a tout lieu de croire
qu’elle s’y trouve éffectivement.” ! 7

‘* 3°. Il y a plusieurs aurores boréales, qu’on ne sauroit
voir en mémes tems de deux endroits peu éloignés Pun de

Pautre, ce qui prouve qu’elles ne sont pas toujours 4 une hau-
teur considerable, et qu’elles se trouve sGrement dans notre at-
mosphere. En effet, on voit cette lumiére 4 Leyden tandis qu
on ne la voit pas 4 Utrecht, on lappercoit 4 Utrecht lorsqw’
elle n’est pas visible a Leyden. Combien de fois ne lobserve-
t-on pas en Hollande, quoiqu’ elle paroisse rarement en France
et encore plus rarement en Italie? Disons donc que c’est une
lumiére contenue dans notre atmosphere, et qu'elle ne s’y éléve
pas méme fort haut,” &c. &c.

His argument against the calculations on the method, of
finding the height by the parallax is, that different auroree
are viewed by the different observers; though he acknow-
ledges that they are generally seen in the north ; which, it
would seem, should be considered a very singular thing if they
were only in the region of the clouds.

Without entering into the question of the aurora being in
the earth’s atmosphere, to which we can yet hardly fix a de-
finite limit with certainty, we see that his arguments on its lo-
cality and connection with clouds are quite specious and un-
worthy of a philosopher. What he says as to its frequently -
not being seen in places only a few miles distant at the same
time, amounts, even if it were shown that the observers were
on the look-out at the same time, with no obstacle to inter-
cept the view, toa vague negative argument,. which would

Mr Potter on the Aurora Borealis. | 213

not render actual measurements the less necessary. And this
would become so easy for a low elevation of the meteor.

Those who do not wish to take even so much trouble, may
_ satisfy themselves by viewing a stratus cloud which passes any
where near the zenith. If this cloud be really of pretty nearly
av equal breadth throughout its whole extent, it will, in con-
formity with the rules of perspective, appear much broader
near the zenith than m its more distant parts near the horizon.
Now, in a symmetrical regular arch of an aurora, no similar dif-
ference in breadth is ever perceptible,—a sufficient evidence
of their great distance from the observer. :

As to his second argument, it would at most show the me-
teor to be connected oth the terrestrial system, and the view
first brought forward by Dr Halley, which has since been
completely established by Mr Dalton, that it is connected with
the earth’s magnetism, is now universally admitted. Never-
theless, the apparent motion of the meteor, and particularly
its tendency to pass southward, are still subjects for inquiry
and discussion.

It is one of the most singular features in the history of the
observations on the aurora, that its connection with the earth’s
magnetism should have escaped the notice of such inquirers as
Mayer, Mairan, and Muschenbroek, who all refer the meteor
to the true north, though the magnetic declination was about
153 degrees west at London in 1731. And though some ob-
servations are recorded where it was noticed not to coincide
with the true north, it is not the less to the credit of Dr
Halley, that this great man, on the first aurora he saw, namely,
the famous one in March 1716, which drew the attention of
so many learned men throughout all Europe to the subject,
perceived at once its great distance and height, and argued
also on its connection with magnetic phenomena.

Near the close of my former paper, I remarked that the
manner of finding the elements of an auroral arch from an ob-
servation of the points in which it cuts the horizon, and the
altitude of its highest point, was not the only way in which
we might consider the subject ; assuming it still to be a small
circle round the magnetic axis, and in a plane perpendicular
to it; but that we might substitute in place of the equation

ig
214 Mr Potter on the Aurora Borealis.

of the plane of the horizon, that of any other plane passing
through the place of observation.

The most general way of treating the problem is to take
the plane at right angles to the magnetic meridian, but making
any angle with the vertical line. Thus we arrive at a general
formula, which will be discussed below, and from which we
deduce that for the plane of the horizon as a pariiadhin case,
and it is the simplest one.

But it will not be without service to make observations for
planes of different elevations on the same arch. For if, as
some philosophers maintain, there are more virtwal magnetic
poles than two on the earth’s surface, we ought to find con-
siderable deviation from a circle in the direction of the symme-
trical rings or arches. But if we find a close coincidence, be-
tween the results furnished by the different points on a high
and extensive arch, we must consider that there is only one
such pole for each hemisphere ; and if the electrical theory
shall be established, which, from recent experiments, there is
reason to expect, we must allow the irregularity in the direc-
tion of the magnetic tendency on the earth’s surface, to arise
from partial and local causes, such as the situation of places
with respect to large continents and the diurnal rotation, or
the effects of prevailing winds, &c.

To proceed to the general problem, let Fig. 6, Plate II. re-
present a view of an auroral arch, the plane A E X being in the
magnetic meridian, and ‘the line A X being its intersection with
the horizon. The data required for the solution of the pro-
blem, are the angle E A X, or the elevation of the arch, the
angle D A X, or the inclination of the plane D A F, — that
of the horizon, and the angle D A F.

Then if a be the place of observation in Fig. 7, a Me a
portion of the earth’s surface, M O the magnetic axis, and ef
a portion of an auroral arch, we may take the centre O as the
origin of the co-ordinates, and put ¢ = the trig. tang. of the
angle ca X, f= the trig. tang. of the angle daf, i bemg =
the trig. secant, and j = trig. tang. of the angle of inclination —
daX, and g = the trig. contangent of the magnetic polar dis-
tance of the place of observation, or = the trig. tang. of the
angle M Oa.

Mr Potter on the Aurora Borealis. 915

_ Then it will be seen that the arch being at an equal height
in every part above the surface of the earth, it will be every-
where equally distant from the centre, * we will represent this
distance Oe by R, putting r for the mean radius of the earth,
and 7’ that of the small circle considered in its own plane. We
have then for the points of the small circle in the plane of 2 z, |
z=r+ea, 2+ 22 = R*, and («x — a)? + (eg —cy = r”,
and in the planedafiv =r+ja,y¥ =fiz’, af? + y? 4 x?
= R*, (# — a)? + y” + (x —c)? = r2, we havealsoc=ag
and R*? — r? + a? +’.

These equations are sufficient to determine the circle. In
the elimination it is better for simplifying the formula to put
t= 1 +? f? +7?,m=-1+e,n=1+8°,0=1 +I28;
andp= 1 e+g.

We then arrive at this equation,
a=r (= bea acins l aa nie) which we see is

Lp?n — mon
of the same form as the one we found in considering only
the points of intersection on the horizon; and, in fact, if
we make the angle of inclination equal to zero, it then co-
-incides with the horizon; and we have i = radius = 1, and
j = 0, these give us /— 1 +,f2 and o — |, and the equation
lpg + 2ep—mg
lp?n—mn |
found before. As the height of the meteor, and its distance
from the observer, are generally the only elements required to
be known, we may shorten the calculation by finding the imme-
diate analytic expressions for them. .Thus, the height being
R — 1, we have only to find the value of R and subtract from
it the radius of the earth ; but substituting the value of a in
the above equations, we find for the horizontal plane the follow-

above becomesa =? ) the same as we

2 ae
ing easy and short formula, viz. R = 2r / ( or ap a i)

“ We here neglect the spheroidal figure of the earth, as it remains yet
to be determined whether the observations can be taken so accurately, on
such a meteor as the aurora, as to render such nicety in calculation of ser-
vice. If it is found that they can be, it will become necessary also to cor-
rect the angles observed, from the consideration, that the arch is a view of
a cylindrical ring, of which the figure of the section would require to be
ascertained.

216 Mr Potter on the Aurora Borealis.

Then knowing R, r and the angle eaO in the triangle ea O,
we find the distance, or the side ae, by the ordinary WigAne:
metrical rule.

When we take the extent of the arch, on any other plane
than that of the horizon, the formula for the value of R be-
comes less simple; by following the same plan as before, we
find this formula, viz. :

e? Lo? p? +. 2m o2 p2—ejmoep— ejlo 1
R=2r v( pipe “ES JF pm 6AbO ma #3)
And when we know R, we easily find the distance as in the
other case.

I have not yet been able to make observations for any other
plane than that of the horizon, but if the aurora shall occur as
frequently next winter as it did the last, I hope it will not pass
over without some observations being obtained which will tend
finally to settle the question of the height of the meteor above
the surface of the earth. I propose keeping a vigilant look
out for displays of it on which I may myself make observa-
tions with such an instrument as I have. But I should be glad
to hear that others, with better instruments, may feel suffi-
cient interest in the inquiry to seek opportunities of observing.
For the guidance of such friends of science, I will take the li-
berty to suggest, that it will generally be found best to take
the measurements for the under or inner edgé of the arch,
when it is not a very high one, aboye the horizon ; for in this
case the under edge is almost always well defined, whilst its
upper one is frequently so diffuse that two observers would
seldom agree to less than 30’ of a degree where it ended. When
the arch passes at an altitude approaching the zenith, it will
generally be immaterial on which edge the observation is made.

I have not yet met with an observation which would en-
able me to calculate the arch of the 25th December last, by
the parallactic method, but I hope some observer will yet ap-
pear who has recorded an observation of it sufficient for the
purpose. In the meantime, I give the height and distance as
brought out by the analytical formule.

The lower arch of the aurora had an altitude of 20° for its
under edge in the magnetic north, and it cut the horizon about
61° west of this point for the same edge. . |

Mr Potter on the Aurora Borealis. 217

-Therefore, taking e = trig. tang. 20°, f = trig. tang. 61°,
and the magnetic polar distance of the place of observation
being 41°, we have g = trig. tang. 49°. From. these data I
find its distance to have been 412.5 miles, its height 159.4
miles.

In looking over the history of the aurora, we see that the
calculations of Mairan, Cavendish, and Dalton, on various
' trigonometrical bases, of from about thirteen miles to some
hundreds, agree with mine in placing the meteor always at a
great elevation, without a single opposing measurement from
- good observations in favour of the contrary opinion. The
lowest altitude determined, namely, that for the aurora observ-
ed by Cavendish, had still a locality such that it is clear it
must be ascribed to other causes than the winds and clouds of
the denser part of the atmosphere.

‘Though, from its position, we are hardly ever likely to be
able to demonstrate actually in what these causes consist, we
may yet, by comparing the different theories which can be
advanced, form our choice of the one which is most consonant
with our previous knowledge and the laws of nature hitherto
established. And as my own opinion, founded on observation
and comparison with other natural phenomena, is somewhat
different from any I have seen, I shall deem no apology neces-
sary in here submitting it.

I have been struck with the similarity of the light general-
ly called electrical in the vacwwm of a mercurial barometer and
that of the aurora. The exhibition of this light has general-
ly been considered a test of the goodness of the instrument.
But it may be seen very completely in the comparative baro-
meter attached to the condensing steam-engine, which general-
ly in a Jarge long-stroke engine, oscillates between 1. and 1}
inches every stroke of the piston, and about two to three inches
of mercury below the atmospheric pressure. When the mer-
cury is falling in the tube there is seen a pale flickering light,
which ceases when the mercury commences to rise again. ‘That
is, the light is seen only when the vacuum (as used in com-
mon parlance ) is becoming worse and the mercury falling.

In whatever way we may explain this phenomenon, the |
light of the aurora has a very great resemblance to it.

218 Mr Potter on the Aurora Borealis.

But if we consider this light as arising from the mercurial
vapour, it will be asked, from. whence could such a metallic
vapour arrive at the highest regions of the atmosphere? In
answer, I would say, tell me whence come the meteoric stones,
and I can give as likely an origin for such a metallic vapour.
He would be very hardy at the present day, and I think little
versed in chemistry, who would venture to assert the non-ex-
istence of metals in such a state, even at low temperatures.
We know that aqueous vapours exist at temperatures below
the freezing point, and we see that many metals, as zinc, arse-
nic, mercury, &c. are easily distilled. We find also, by the
evidence of our sense of smelling, though so much inferior in
the human species to what it is in many of the lower animals,
an impression of the existence of a metallic vapour, when we
are in places where metals are worked. But for a ready ex-
periment, let any one take a piece of iron or steel, and rub away
the coating of varnish or oxide which may be on its surface
upon a rough stone or file, on removing it to a short distance,
he will readily perceive, if his olfactory sense be not particu-

larly dull, a peculiar metallic odour, which cannot arise other-

wise than from the iron, and which is only perceived in its
vicinity. |

I must acknowledge that there is quite as much difficulty
in accounting for metals in this state floating in space, as there
is in accounting for the origin of aerolites. But the phenome-

na of the aurora are undoubtedly, in my opinion, best ac-

counted for, on the view that the metals which form so prin-
cipal and characteristic a portion of meteoric stones exist also
in a state of vapour, moving in space ; which, arriving within
the influence of the earth’s attraction, are brought into a state
of commixture with the higher portions of the atmosphere.
The forms of the meteor, the peculiar light, and the posi-

tions with respect to the magnetic tendency, must then result

from the necessary effect of the earth’s electrical or magnetic
state.

The rarity of the matter which causes the aurora is quite in
agreement with the tenuity which must exist in a metallic
vapour at exceedingly low temperatures. For we find a mass
of forty to fifty miles m depth, hardly, in a telescope, affect

e

Contributions to Scientific Bibliography. 219

the intensity of the light of very small stars. The density of
these masses, as I have computed, must be dess than the one
ten-millionth part of that of the mercurial atmosphere in the
Torricellian vacuum, to give such a light as we observe,—a
tenuity we can scarcely form a conception of.

Smepitey Hatz, August 3, 1831.

Arr. V.—Contributions to Scientific Bibliography. By aCor-
RESPONDENT. Communicated by the Author.
Tue scarcity of a book, which has nothmg else to recommend
it, is a fact which is hardly worth knowing ; but when the work
has any real value, either from intrinsic merit, or from forming a
link in the history of science, its scarceness then becomes an
object of importance. It is constantly found that errors are
perpetuated by writers who satisfy themselves by copying what
they find at second hand, and these errors can never be cor-
rected without reference to original authorities. It is useful,
therefore, to know not only what books are scarce, but also
(when it is possible) where they are to be found. It must
often occur to those who have access to large libraries, that
they meet with works which they had never before heard of ;
and the books so discovered will sometimes contain matter
which had been looked for in vain. Neither is it to be attri-
buted to a mere selfish anxiety for accumulation, when any
one employs himself in collecting with this view. Much is:
learned from what is in our own possession, and even in the
search for it; and every one who has indulged himself in col-
lecting books, must have often found advantage from what, at
the time of the purchase, he did not foresee that he should de-
rive any particular use. ‘This of course supposes that he has
collected with some discrimination; and if in that case he should
sometimes be induced to give a higher price than he otherwise —
would for a book in consequence of its scarcity, he is not on
that account alone to be blamed. There are other individuals.
also to whom some anecdotes on this subject may not be un-
interesting; and the following remarks may hereafter be suc-

t

a °

220 Contributions to Scientizic Bibliography.

ceeded by others of a similar description, if they are fae to
contribute even to liberal amusement.

B: riggs’s Arithmetica Logarithmica, 1624.

Dr Hutton gives an account of “ this stupendous work,” as
he justly calls it, in his well-known history of logarithms.
He furnishes an ample detail of its contents; but in some of
the particulars respecting the book itself, his description ap-
pears to require correction. The book contains, as he observes,
the logarithms of all numbers, from 1 to 20000, and from
90000 to 100000 carried to fourteen places of decimals ; but he
adds, ‘some writers say that there was another chiliad, namely,
from 100000 to 101000 ; but none of the copies that I haveseen
have more than the 30000 above-mentioned, and they were all
regularly terminated in the usual way with the word Finis.”
Gardiner, in the preface to his quarto T'ables of Logarithms,
(London, 1742,) mentions his having particularly used this chi-
liad, but it certainly is hardly ever to be found. ‘There are, how-
ever, at least two copies of it in existence ; the one isin the Savi-
lian Library at Oxford, and the other is in the possession of the
Earl of Macclesfield. It is evident that it formed no part of
Briggs’s original design, but was printed separately after the
great work. It consists of only a few leaves, and these cir-
cumstances will account for its having been so generally lost.

From the letters with which the different sheets are marked,
it is clear that Briggs’s original intention was not to leave his-
great. work in the imperfect state in which it has come down
to us; and indeed Wingate says in his preface to T’abule* Lo-
garithmice (Lond. 1633,) that after the publication in 1624,
he ‘endeavoured, with all the expedition that he and his
friends could make, to publish a perfect table, which should
contain the logarithms of all numbers from 1 to 100000, —
Howbeit, before it could be quite finished, that table which he
intended was brought home to him ready calculated and pub-
lished in the low countries without his consent or notice, he
having directed an easy way (in his book above-mentioned)

* These are ye for 7, not 8 place of decimals, as Hutton describes
them.

Contributions to Scientific Bibliography. 221

how the logarithms of the intercepted numbers might be dis-
covered.”

The copy of the Arithmetica Logarithmica in the Savilian
Library was probably Briggs’s own, and there is between the
leaves of it a letter which he had written to his friend Mr Wells
of Deptford, giving instructions how to proceed in calculating
for him. This agrees well with Wingate’s statement; and it
is to be regretted that Vlacq should have interfered with the
author’s plan. If he had not, we should have had the work
completed for the whole series of numbers to fourteen places
of decimals. Vlacq’s, indeed, go to ten places; but his hurry
to anticipate those who ought not to have been interrupted,
made him suffer his work to go through the press in a most
careless manner. The number of errata is really disgraceful,
and particularly to be reprobated in a publication like this.
It is true that figures require more than common care in the
revision of the sheets, but it is equally true that errors in print-
ing them are of more than common importance.

Besides Vlacq there was one of his own countrymen whom
Briggs had likewise some reason to complain of ; but Hutton’s
statement leaves an inaccurate impression of what he did. He
says, ‘‘ In 1631 was printed in London, by one George Mil-
ler, a book containing Briggs’s logarithms, with their differen-
ces, to ten places of figures, besides the index, for all numbers
to 100000, as also the logarithmic sines, tangents, and secants,
for every minute of the quadrant, with the explanation and
uses in English.” He then gives a quotation from Norwood’s
Trigonometry, in which this publication as well as Vlacq’s are
severely reprobated ; but the fact seems to be much over-stat-
ed. Miller published a title-page with an imperfect preface
made up from Briggs’s Latin, but it does not appear that he
ever reprinted the logarithms. This English preface i is in the
British Museum bound up by itself. It is sometimes met with
in the same volume with Briggs’s own logarithms to fourteen
places, to which it certainly cannot belong; but a copy in the
Savilian Library clearly points out the distinct object with
which it was printed. It isthere prefixed to Vlacq’s own book,
to which the description in the title-page exactly answers. ‘To
remove all.doubt on this subject, it is only necessary to com-

222 Andres del Rio on Silver Ores,

pare the tables of errata, and it will be found that the English
is a mere translation of the Latin table given by Vlacq. This
clearly proves that it was never intended for any reprint of the
work which Miller might have had executed in England, but
only to assist the mere English reader in the use of the Dutch
publication. ‘This certainly was an assistance to the circula-
tion of what might be considered in some measure as a pirated
book, but does not amount to a substantive act of piracy in
itself. ,

Art. VI.— Silver Ores reduced by the Method of Becqueret.
By Anpres DEL Rio. (Read November 5, 1830.) Commu-_
nicated by a Correspondent. :

I uave the honour to present to the American Philosophi-
cal Society, the result of some curious researches, which in more
dexterous hands may become interesting. ‘They were sug-
gested to me by the beautiful experiment of M. Becquerel,
inserted in the Annales de Chimie et de Physique for Septem-
ber 1829. He introduced into a glass tube some carburet of
sulphur, with a solution of nitrate of copper, which, being of
‘less specific gravity, floated upon its surface ; and by means
of a copper wire he established a communication between the
two liquids. He observed that the surface of the wire became
coated with protoxide of copper, while smail tables, assuming
a metallic anid glistening appearance, were deposited on the sides
of the glass tube. These M. Wohler has since shown to be formed
of sulphuret of copper; whence he considers the method of |
Becquerel as being merely “‘a new mode of forming sulphurets,”
to which, I think, he should have added, ‘‘ by the decomposi-
tion of other sulphurets.” Indeed, I introduced severally into
three small glass tubes, some small lamellz of ductile and some
fragments of brittle silver glance and red silver ore. ‘These,
being exposed to the action of nitrate of copper and a copper
wire, were reduced in eight days to the state of metallic silver.
I repeated the experiment on the ores in’small fragments,
which became coated with silver in five days. The formation of
silver was even apparent on the second day at the points in
which the ore came in contact with the glass. By what pro-

reduced to the Method of Becquerel. 223

cess nature invests silver glance and red silver ores with native
silver in the mines, is a question which I do not pretend to
solve.

In operating upon the fragments of silver glance, which
were coated in the preceding experiments with metallic silver,
I added a little quicksilver. In fifteen days the ore was trans- —
formed into an amalgam of silver. The brittle sulphuret and
the red silver ore required nearly three weeks for their com-
plete amalgamation. According to M. Wohler the carburet
of sulphur is decomposable in the same way by diluted nitric
acid. I did not succeed in decomposing the dark red silver
ore by nitric acid, until after a subsequent saturation of the
acid with copper.

These experiments afford us instances of the reduction
of silver ores without common salt, and sulphuret of iron
and copper (the magistral of the Mexicans.) I always sus-
pected that the latter substance was very mischievous in the
process of amalgamation, occasioning the great loss of silver
and mercury which are daily experienced. The silver being
oxidized at the expence of the sulphuric acid, retains its oxy-
gen with more tenacity, as has been shown by M. Berthier,
than had been previously admitted; and especially when in con-
tact with the oxide of copper, which possesses this property to a
high degree. ‘I'he same probably happens with the mercury;
and the sulphates, bisulphates, and subsulphates, which are
thus formed, are lost for ever in the process of washing.
Hence, I think, they roast their silver ores in Saxony with
' common salt alone; and they treat the chloride of silver by
mercury. By this means the loss of mercury amounts only to
four ounces per five marcs of silver obtained in the working
of ores that contain two ounces per quintal. (See Note A.)
How satisfied would we be in Mexicoif our loss were no greater?

I trust that the pupils of the College of Mines of Mexico
may derive some advantage from these small experiments of
mine. Perhaps I have thus approximated to the discovery |
made by my lamented pupil Valencia, and which he unfortu-
nately carried with him to the grave. I can state as a fact,
that by his genius he had discovered the means of avoiding
the loss of mercury termed the consumido. Such are the fruits

NEW SERIES, VOL. V. NO. If, OCTOBER 1831. P

224 M. Chevalier’s Answer to Dr Goring’s

resulting from colleges of mines. In my last letter I suggest-
ed to him the use of the protomuriate of tin, not of the nitrate
of copper; and in his reply he informed me that his method
was so simple, that he feared the workmen would deprive him
of the fruits of it. As the mail was closing, he postponed the
communication to his next letter, which, however, he never had
an opportunity of writing, having previously, as well asmany .
others of my able pupils, fallen a victim in the war of inde-
pendence.

Should the Philosophical Society continue their liberality to
me, by supplying me with a fragment of the white silver glance
(weisguiden of the Germans), I propose to extend my experi-
ments to that ore.

Note A.—The Mexican amalgamator divides his loss of mer-
cury into two parts; the first he terms consumido, which is al-
ways equal at least to the weight of silver obtained. The
second termed perdida, is the waste in washing, &c.

Art. VII.—A Letter from Cuaries Cuevarier, Optician in
Paris, to Dr Gortne, being an Answer to his Paper pub-
lished in the Second Volume of the New Series of the Quar-
terly Journal of Science, p. 248, entitled, ** A Critique on
the thick Aplanatic Object-Glasses for divergent rays of Vin-
cent Chevalier aine et fils.” Coansillligaiee by Dr Gortne. |

Sir,

[ wave read with the greatest interest the different papers you
have published on the microscope, and which have. greatly
contributed to. the improvement of those useful instruments.

As you have had the kindness to honour our labours by
writing an article or critique upon the achromatic object- glasses
which we worked for Mr Lister, I hope that you will receive »
favourably the details which I here transmit to you relating to
our achromatic microscopes, and which are in answer to your —
critique, bearing date from October to January 1828, (See Dr
Goring’s Remark A, p. 238,) in which, after having exa-
mined the different object-plaaald of Mr Lister, you make seve-
ral observations, to which I reply.

* Paper on Aplanatic Object- Glasses. 225

It is very true that the achromatic glasses composed of a
flint-glass, and a crown-glass, or double object-glasses, give
rays well corrected only for the central pencils, and confuse
the oblique ones ; but their advantages in clearness and in fa-
cility of construction, make them generally preferable to triple
ones.

If the object-glass of Mr Lister has its concave tarnished,
the fault is to be attributed to the flint-glass of Guinand ; and
as to the appearance of dust visible im the substance which
unites the two glasses, we can assure you that it is almost im-
possible to avoid that very slight inconvenience in any object-
glass, whether cemented or not. The advantage of the glued
glasses is, that, if they include a little dust, they do not retain
any moisture between the surfaces which are in contact.

The object-glasses of ten and fourteen lines must necessarily
be ineffective upon test objects, considering their focal distances.

It is probable that some of our first object-glasses have not
been perfectly adjusted ; but this is also an imperfection which
it isnot possible to avoid, rigorously speaking, in the construc-
tion of these minute glasses. For the rest, the approbation you
concede to our lenses in these words, “ nothing can surpass
the beautiful simplicity of the curves of M. Chevalier,” is doing

-us a great honour. (See remark AA.)

Euler composed his object-glasses of two bi-convex lenses of
crown-glass, and a bi-concave of flint, to form a triple object-
glass of six lines focal distance, (see the following extract from
the work of Euler,) with a large aperture ; and it is because our
microscope is achromatic, (though the lenses are differently dis-
posed,) that it is established on the principles of Euler.

You find our quadruple combination of two double object-
glasses perfect; but now we combine together three lenses of
short focal distances to form sextuple object-glasses. This com-
bination is scarcely possible except with our lenses, which have
the indispensable requisite for the perfection of microscopes, of
being very thin, and of a very small diameter, which conditions
cannot be easily fulfilled in triple glasses.

Our object-glasses are glued together with a mixture of tears
of mastic and turpentine, and that process ought to appear as
good in theory as it is in practice, the surfaces in contact hav-

*
226 M. Chevalier’s Answer to Dr Goring’s

ing rigorously the same radius, and being joined together by
a substance as transparent as glass, which obliterates their sur-
faces, ‘The introduction of dampness is prevented, and the re-
flections produced at their interior surfaces are neutralized ;
therefore they are much more transparent, Being, moreover,
invariably fixed, they can be employed with as much facility
as simple lenses. This it is that makes me think that this is
the true method of adjusting achromatic object-glasses, and that
if the practice has not been extended to all, it is because the
elueing has not been well performed ; if well executed, it is
always advantageous.* |

It is true that we were too much impressed with the idea,
that achromatism being once obtained, distinctness and the con-
densation of an artificial light ought to be sufficient ; but after

your learned advice, we could observe that a large aperture was —

also an improvement (perfectionnement,—see Remark B at the
end,) which must be obtained in microscopic lenses; aud that
if the effect of object-glasses does not entirely depend upon
their aperture, at least, cateris paribus, the object-glasses which
admit the greatest opening are the best and the most pene-
trating.

Since the object-glasses were sent to Mr Lister, one of those
systems of six glasses, composed of three object-glasses placed
one upon the other, each four lines focal distance, has been
sent to you. (See Remark C at the end.) I have studied the

letter in which you make some very clever remarks upon that

sextuple achromatic system. You say with reason that achro~ —

matic lenses must be achromatic, if it was merely on account
of their name. ‘The advantage of the set in question you ad-
mit to reside rather in their aplanatism than in their achroma-
tism, because you have perceived that a little colour does not
alter their performance sensibly, as you have seen with them
the lines and lozenges on the scales of the Podura plumbea.
(See Remark D.)

I say on this occasion, that it is very difficult to judge of the

perfect achromatism of a lens, or of a system of lenses ; for

* The cementing of achromatic object-glasses was first executed in France,
together with the practice of burnishing them into settings for the purpose
of combination with facility. ,

4

ee

Paper on Aplanatic Object-Glasscs. 227

with the most achromatic glass, by a simple modification of
illumination, we can show the outlines of the object fringed,
with colours, but by a little change in the position of. the re-
flecting mirror, this can be made to disappear entirely. (See Re-
mark E.) This iris or rainbow often proceeds from the eye-
glass. This is so true, that, with a catadioptric microscope, it
happens sometimes that the outlines of objects are coloured.

I believe that when we compare the effect of two achromatic
lenses, they must be of the same focal distance, if you wish to
judge rightly of their merit, as to their freedom from disper-
sion and spherical aberration ; therefore, it would not be right
to compare (with reference to these qualities,) a lens of six
lines, or of an inch focal distance, with an achromatic system
representing a power of less than one line. The best object-
glass, in my opinion, is that which is the most penetrating, viz.
that which shows with most nicety the little details of test-ob-
jects, even if it gave a little tinge of colour, which it is almost
impossible to destroy without a great reduction of the aper-
ture; but then what is the use of a perfectly achromatic
object-glass, if it has no power over the test-objects ? _

Certainly I do not deny the advantage of a glass of short
_ focal distance perfectly free from the aberration of sphericity
and refrangibility, as it would fulfil the conditions of the high-
est degree of perfection. I have seen achromatic lenses of all
manufacturers. More than a thousand of these glasses have
passed through my hands, and I have never found that ulti-
matum so much to be desired ; therefore, I still believe that
the most penetrating object-glass will be the most useful, and
that to which the preference must be given. As to other matters,
be pleased to let me know what you think of the system of len-
ses, belonging to Mr Cuthbert, which is composed of the len-
ses marked.

0 of 12 lines focal distance, lens plano-convex.

1 of 4 lines do.) 2 1 Tide:
2 of 4 lines do.) .:arieds.
3 of 2 lines do. - meniscus.

Three of these lenses are always employed together, whether
you take away the glass marked 3 or that marked 0, and em-

m
228 M. Chevalier’s Answer to Dr. Goring’s

ploy the object gina, 1, 2, 3, to obtain the maximum. _ (See
Remark F.)

The examination which you will be pleased to make, Sir,
of the last sextuple object-glass which I have addressed to you
composed of

1 lens meniscus, focal distance 4 lines.
L «do. - ~ 3
1 do. 2 bs Q

will confirm, I hope, the very correct opinion you have that the
perfection of object-glasses i is found in short foci. (See Remark
G.) Therefore, it is towards this point that our exertions will
be directed, and I think that in a few months we shall in-
crease the power of our last set of object-glasses, (see Remark
H) composed of

1 lens plano-convex, focal distance 4 lines.

1 —— meniscus Hs b 2 do.
Diese do. ‘ ‘ 2 do.

I think that opticians must direct their attention and their
care to achromatic lenses, of a large aperture, thin, of small
diameter, and of the shortest possible focal distance, and when
they have succeeded in perfecting them, then will meh wy 5
be carried to their highest degree of excellence.

I have read the interesting paper of Mr Lister upon a new
method of correcting the object-glasses of microscopes. I think ~
that this plan will give facilities for the fabrication of object-
glasses of a moderate focus, and that by this discovery, Mr
Lister has advanced a step farther towards the enepaares: of
microscopes.

Professor Airy proposes in his papers to supplant the
achromatic system invented by Dollond and Euler (which is
founded on the marvellous structure of the eye) by another
process, in order to ascertain to which the preference should —
be given. I believe it will be sufficient to consult a work, the
title of which is, Dioptrice, auctore Euler, Petropoli, 1769,
1771, and the Analytiche Dioptrick, Leipzig 1778, or better
to compare a good achromatic microscope made according to
Euler’s system, with the best instrument constructed by that of
Mr Airy.

Paper on Aplanatic Object-Glasses. 229

In replying to your critique, I find myself under the neces-
sity of making known the different improvements made in mi-
croscopes since their origin, more especially as to what con-
cerns achromatic lenses; I shall therefore endeavour to trace a
short notice concerning them, in which I shall enlarge particu-
larly on what has been done in France in this part of dioptricks.
In general, the invention of the compound microscope is attri-
buted to Drebbel in 1621; there are also some opinions in
favour of Zacharias Jansens or Joannidas de Middlebourg,
and Fontana. Hook improved it by the addition of several
lenses. Huygens investigated its theory as well as Toricelli,
who perfected the optical instruments then known.

Since their time many of the most celebrated geometers and
artists have occupied themselves with the improvement of mi-
croscopes, and have principally sought to construct an instru-
ment which, endowed with considerable magnifying power,
light, and clearness, should also be of easy and universal ap-
plication.

Schmitz, Cuff, Euler, Dollond, Adams, Delabarre, Amici,
and Charles, much improved compound microscopes ; for two
centuries they were constructed in England, in Holland, in
Italy, and in France, until this part of the science of dioptricks
seemed to be exhausted. Nevertheless new experiments demon-
strated that these instruments were still far from perfection ;
in fact, an achromatic combination had not been employed in
the composition of object-glasses, which is nevertheless an in-
dispensable condition for the attainment of perfect images.

Euler first occupied himself in the perfection of this instru-
ment. ‘lo him it in fact belongs to have applied to micro-
scopes the happy combination of Dollond. (See remark I.)
Although achromatic lenses were invented in 1760, yet it was
not till 1774 that Euler proposed to employ them in micro- |
scopes, and so slow and difficult is the progress of the arts,
that it was not till the end of 1823 that achromatic lenses for
the microscopes were actually constructed. Even.in 1821, M.
Biot remarks in his T'raité de Physique, ‘‘ that a great part
of the imperfections of microscopes depends on a want of achro-
matism, which becomes the more insupportable when we wish
to use high powers. It is unfortunately impossible,” he adds,

230 M. Chevalier’s Answer to Dr Goring’s

“ to correct this defect entirely, since we cannot achromatise
lenses as small as those which the microscope requires. re

About this epoch the celebrated Bavarian optician, Fraun-
‘hofer, constructed achromatic lenses having long foci, and con-
sequently they were inefficacious upon difficult objects ; and
they could doubtless be applied only for the observation of
objects of large size, which i is not generally the purpose of a
microscope.

At the end of 1823, Vincent and Charles Chevalier, opti-
cians in Paris, began, on the recommendation of M. Selligue,
to construct an achromatic microscope, whose object-glass was
composed of four achromatic compound lenses of two lenses,
each of the compound lenses having a focus of eighteen lines,
with a diameter of six lines, and a thickness at the centre of
two lines. These object-glasses were placed, the one before
the other, in order that they might be employed, together or
separately, in the manner long practised with simple lenses.
The aperture placed between these lenses was one line. * This
microscope was presented to the Academy of Sciences of Paris
on the 5th April 1824. M. Fresnel made a favourable re-
port upon it on the 30th of August following. As M., Sel-
ligue did not inform M. Fresnel that these opticians had taken
an active part in the construction of this instrument, and that
they had made sacrifices of all kinds for its success, they
abandoned M. Selligue and his imperfect microscope, (see Mr —
Lister’s Memoir,) in which, however, he gave the happy idea
of combining achromatic object-glasses,—a method generally:
adopted, and to which is owing its actual superiority.

MM. Chevalier and Son were, from that time, occupied
alone in the improvement of the object-glasses and of the mi-
croscopes ; and in September 1824, they had constructed the

* This natural philosopher does not mention the attempts bene by
‘Dollond, Pollard, and several other amateurs, or English and French op-
ticians, nor the four object-glasses with three lenses, which, having be-
longed to M. Charles, are in the Physical Cabinet of the Conservatory of
Arts in Paris. The same may be said of the similar-works undertaken in
1815.by M. Amici, because the object-glasses then made gave unsatisfac- -
tory results, and were consequently useless, having only a nominal proper-
ty.—Note of M. Chevalier. (See Remark K at the End.)

Paper on Aplanatic Object-Glasses. 231

first plano-convex achromatic with two glasses united, of a _
short focus, thin, and of a small diameter. (See Remark L.)
This lens had a focus of four lines, a diameter of two lines, and
a thickness of one line at the centre, and it was with lenses of
this kind that the impreved microscope was constructed which.
was presented to the Societé d Encouragement on the 30th
March 1825. On this occasion the reporter, M. Hachette, re-
marked‘: ‘* The images seen through this microscope are free
from every sensible aberration, either of sphericity or refran-
gibility : objects, whether opaque or transparent, appear in it
with a distinctness equal to that of achromatic telescopes.

The first achromatic object-glass which had been made in
England was the triple object-glass of nine-tenths of an inch
focus, executed in 1824 and 1825 by Mr Tulley, at the desire
of Dr Goring, (See Remark M,) and of which an account was
published in different scientific journals. Mr Tulley after-
wards greatly improved his first work, and Mr Dollond was
also occupied with this part of dioptrics. With respect to Dr
Goring, he has, by means of his learned memoirs, done a ser-
vice to the opticians of every country, by pointing out many
methods of improving the microscope.

On the $d October 1826, Professor Amici wrote in the fol-
lowing manner to MM. Chevalier and Sons: “ I have receiv-
ed your letter of the 24th September 1825, as well as the no-
tices and the memoir which you have addressed to me. In
thanking you for this present, which has been very agreeable
to me, I have learned, with great pleasure, that you have ar-
rived at a perfect construction of achromatic object-glasses for
microscopes. ‘This interesting part of optics has been general-
ly neglected, perhaps owing to the great difficulties which it
presents, and science still requires that skilful opticians should
occupy themselves with the amelioration of the achromatism
in lenses of short foci. Naturalists will be happy to learn that
you have offered them microscopes according to the principles
of Euler, which surpass all dioptric microscopes. I hope it
will not be long before I shall have an opportunity of admir-
ing your instrument at Paris, and I shall then have the plea-
sure of showing you a small work of this kind, which, as an
amateur, I have constructed for myself.”

. + '
232 M. Chevalier’s Answer to Dr Goring.
According to Mr Lister, Mr Amici abandoned in 1815 his

‘first attempts upon achromatic glasses, because they were not
equal to his reflecting microscopes; and it was not till 1824,

after the report of M. Fresnel, that the philosopher of Modena

undertook this work, by adopting the system of M. Selligue
with regard to the superposition of object-glasses. He pur-
sued this idea with great success, for on the 25th May 1827,
he brought to France a microscope whose object-glass was
composed of three lenses superposed, each having about six.
lines of foci, and a large aperture, but not cemented. ‘This
‘instrument, united to a great magnifying power, a remarkable
distinctness, as well as the horizontality of the instrument, and
excited the admiration of both philosophers and amateurs.
During the stay of M. Amici at Paris, Vincent and Charles

Chevalier exhibited in the Louvre a horizontal microscope,’

(see Remark N,) constructed on the principles and after the
advice of M. Amici; and this instrument was deemed worthy
of the silver medal. by the central jury.

Since that time several object-glasses have pire made by

Tulley, Amici, and Vincent and Charles Chevalier. These
glasses were the subject .of different memoirs or commentaries
by MM. Amici, Goring, Lister, Lebaillif, which have great-
ly contributed to bring achromatic microscopes to a high de-

gree of perfection ; for we can obtain in France, in Italy, and
in England, efficacious lenses of four lines focus. The latest

trials made in France have proved that it is possible to make
achromatic lenses of two lines focus; and that we may even

hope to carry still farther the power of dioptric microscopes,

such, for example, as to form a compound object-glass of two.

lenses of one and a-half line focus, or of three lenses of two and”
a-half lines focus. . We may then say after this, that in a few
years microscopes will be brought to the highest degree of per-:
fection, since it is probable that we shall then have made the

most powerful achromatic systems.
: CHARLES CHEVALIER.
Paris, Quat pD’Hor.oce, No. 69,

10th February 1831.

8
eS se oe

M. Euler on the Perfection of the Microscope. — 233

Arr. VIIL—On the Perfection of Microscopes... By Lxo-
NARD Evter. Communicated by Dr Gorine.

‘THE best microscopes which have hitherto been made are yet
subject to such great defects. that we have reason to be sur-
prised that the most skilful artists have not been able to
free them from those defects, while they have worked. with so
much success at the perfection of the telescope. In the first
place, we remark generally in microscopes, the great defect,
that they represent objects with less distinctness than telescopes,
which would be entirely rejected if they exhibited such a
great degree of confusion as we are accustomed to suffer in mi- |
croscopes. And we must admit that the more we increase the
amplification of microscopes, the more the confusion is in-
creased, so that we can distinguish almost nothing in them.
The two sources of confusion, the one being the aperture
of the lens, and the other, the different refraction of the beams,
concur equally to render insupportable the confusion with

which microscopes represent objects. :

The best method of diminishing this confusion, would be,
without doubt, in diminishing the aperture of the object-glass ;_
but then we should lose in clearness, which is generally so
little, that in great magnifying powers it is almost impossible
to distinguish the different parts of the object under examina-
tion.

It is also a very great inconvenience im microscopes, espe-
cially in simple ones, that we are obliged to approach so near
to the objects to put them in the focus of the object-glass ; be-
cause if there is any inequality in them, it is absolutely impossi-
ble to recognize the points which are a little out of the fecus.

The surest means of remedying all these defects will be,
without doubt, to employ, as in telescopes, compound object-
glasses of different kinds of glass; and for that purpose, the
last object-glass in which we have introduced the new species
of flint-glass which produces a great dispersion of the rays,
furnishes us with a method well fitted to carry also the micro-
scope to the highest degree of perfection, as it will be easy
for a skilful artist to execute such object-glasses which would

234 $M. Euler on the Perfection of the Microscope.

have only half an inch of focal distance, and which could re-
ceive an aperture of the eighth-part of an inch in diameter.
This would furnish for all the magnifying powers a sufficient

degree of distinctness; but as such object-glasses will cause ~

no confusion either from the aperture or the different refrac-
tions of the rays, the greatest advantage, without doubt, will
be that we could see all objects with the greatest clearness and
distinctness, which will enable the natural philosopher to bring
microscopic observations to the highest degree of perfection.

To facilitate the more the execution as well as the use of
such microscopes, we shall ‘give here the description of one,
which contains only two eye-glasses, and which might serve even
to produce all the magnifying powers, from the smallest to the
greatest, without being obliged to change any thing, either in
the object-glass, the eye-glass, or in the place of the object,
which should be put always at the distance of half an inch be-
fore the object-glass. The only variation is to be produced
in the distance between the object-glass and the first eye-glass,
which will be removed in proportion as we wish to magnify
the object.

Description of the Object-Glass.

1. The object-glass should be composed of three lenses, of
which the first and third are made of crown-glass, and the se-
- cond of that sort of flint-glass whose index of refraction is
1,600; so that the focal distance of the whole object-glass
may be half an. inch, and that it may receive an aperture of
the one-eighth of an inch in diameter. For this purpose the
three lenses of which this object-glass is composed, will repre-
sent little disks, whose diameter will be about the one-seventh
of an inch, and they must be made as thin as their figure will
allow. For the figure of each we shall give here the measures
expressed in thousands of an inch of twenty-seven muilli-
metres.

2. The first of the three lenses, the one which is turned to- |

wards the object-glass, must be of crown-glass, equally con-
vex on both sides, so that the focal distance will be 0,286,
and therefore the radius of each of its sides 0,301.

3. The second lens of fint-glass, equally concave on both-

— ee ee

M. Euler on the Perfection of the Microscope. 235

sides, having its focal distance 0,229, and therefore the radius
of each of the two sides 0,274.

4. The third lens of crown-glass must be eat convex on
both sides, so that its focal distance may be 0,375. We must
give to the radius of the front side 0,644 of an inch, of the
other side 0,287.

5. We must combine these three lenses, so tes -the dis-
tance between the middle of the second lens and that of the
first or third, should be only 0,019, so that the thickness of
_ the whole object-glass will be about 0,057.

6. The object which is to be examined must be always
placed at the distance of half an inch from the object-glass ;
and then there will be no reason to fear that the too great
proximity of the object may cause the least inconvenience.
On the contrary, we shall see all the different parts of the
object nearly with the same degree of distinctness.

Description of the two Eye-Glasses.

7. It will be proper to form them both of flint-glass, for the
purpose of admitting a greater aperture, which will contri-
bute greatly to increase the apparent field, making both of
these glasses equally convex on both sides.

8. The first of these eye-glasses, the one which faces the
object-glass, must have the radius of each side 1,200, and the
diameter of its aperture 0,600.

9. The second eye-glass, turned towards the eye, must
have its focal distance 0,333, and the radius of each side 0,400,
and the diameter of the aperture 0,200.

10. Beyond this glass we must place the eye at the distance
_ of 0,167 of an inch.

11. The distance between these two eye-glasses will be al-
ways ds of an inch, as, according to the nature of the eye, the
last eye-glass must be sometimes nearer and sometimes farther
from the first, which is effected very easily by means of a screw.

Having made these three glasses, the magnifying power
will depend only on the distance between the object-glass
and the first eye-glass, to which it is always proportional.
But we must remark, that,the more we increase the magnify-

236 M. Euler on the Perfection of the Microscope.

ing power, the less will be the clearness, and the ‘portion of
the object which we can see at once.

As to the degree of clearness, it will be proper to observe,
that, if the magnifying pewer is under 20 times, the objects
will appear with their natural clearness as if we were looking
at them with the naked eye. We shall call this degree of na-
tural clearness 1; and we shall express, in the following table,
for each magnifying power, the clearness of the object by the
‘thousand parts of the unit. |

In the same table we shall insert all the diameter of the
part of the object, which will be seen at once by each magni-
fying power.

But to judge of the indict power, we shall refer it, as
is usual, to the distance of eight inches, so that the numbers
marked for magnifying power will indicate how many times _
each object will be seen greater by the microscope than by the
naked eye at the distance of eight inches. |

This being settled, the first column A, of the table. will
mark the magnifying power; the second B, the distance be-
tween the object-glass and the first eye-glass ; the third C, the
degree of clearness; and the fourth D, the diameter of the
portion of the object seen by the microscope.

A B C D

25 0,781 0,800 0,115
50 1,562 0,400 0,064
100 3,125 (0,200 0,035
150 4,687 0,133 0,025
200 6,250 0,100 0,109
250 1,812 0,080 0,015
300 9,375 0,066 0,013
350 10,937 0,057 0,011
400 12,500 0,050 0,010
450 14,062 0,044 0,009
500 =: 15,625 0,040 0,008
600 18,750 8,033 0,007
700 21,875 0,029 0,006
800 25,000 0,025 0,005

_M. Euler on the Perfection of the Microscope. 237

7. B Oi: D
900 =. 28,125 0,022. 0,004
1000 = 41,250 0,020 0,004
1200 = 37,500 0,016 0,003
1400 43,750 0,014 0,003
1600 50,000 0,013 0,003
1800 56,250 0,011 0,002
2000 ~=—- 62,500 0,010 0,002
2500 78,125 0,008 0,002
83000 — 93,750 0,007 0,001

As for the degree of clearness, we must also observe, it is _
not absolutely proportional to the numbers C in the table, but
more to the square of these numbers, so that the clearness de-
creases much more than it is marked in thetable. If you wish
a magnify one thousand times, the degrees of clearness is not

5 of the natural clearness, but only 33009 but that degree of
pay is still pretty great in pompenny. it to the clearness
of the full moon, which cannot exceed 3555; of that of the
sun; from which we see that the degree of clearness which
corresponds to a magnifying power of 100 is still ten times
greater than the clearness of the full moon, which will be suf-
ficient for the objects we may wish to examine.

If we wished, however, to increase the magnifying power,
we must illuminate the objects as we do when we employ the
common microscopes; but it will not be necessary to go farther,
because it is probable that a magnifying power of 300 or 400
times, which represents the objects distinctly, will discover a
great deal more than the common microscopes with a magni-
fying power of some thousand times.

N. B.—This article is an extract from a work published at
Petersburg in 1774, under the title of Detadled Instructions
to bring Telescopes of different kinds to the highest degree of
perfection of which they are susceptible, deduced from the Diop-
tric Theory of Leonard Euler, and written in a way to assist
workmen, by Nicolas Fuss ; with the Description of a Micro-
scope of the most perfect kind, capable of every degree of
magnifying power. Article 7, p. 75 to 83.

238 Dr Goring’s Remarks-on M. Chevalier’s Paper,

Art. [X.—Remarks on Mons. Chevalier’s Paper, and on the —

Memoir of Euler. By Dr Gortnc. Communicated by the
Author. :

A. Ir will no doubt be thought that M. Chevalier has been |
somewhat tardy in his reply; but it must be recollected that,
in order to answer me with effect, it was necessary for him to
perfect his object-glasses, which he has even now scarcely ac-
complished, at least to the extent contemplated by him.

AA. Simplicity is, in my mind, a capital ingredient in all in-
ventions and works of art. M. Chevalier has invented a kind of
object-glass which will assuredly descend to posterity, for it is
almost the only form in which achromatic object-glasses for en-
gyscopes can be made with any sort of facility by moderately
gifted artists; the radii of their inner surfaces being alway ri-
gorously the same, generate double aplanatic foci and a variable
aberration, on which Mr Lister has founded an admirable sys-
tem of correction. ‘These advantages, however, were never
contemplated or applied by M. Chevalier, and are the exclu.
sive discovery of Mr Lister.

B. So effectually had M. Chevalier blinded his object-glasses,
with respect to lined proof- objects, by an excessive reduction of
their aperture, (owing to his ignorance of them at the time,)
that had we been disposed to take an ungenerous advantage of
his insensibility to the value of aperture, it would have been —
easy to have utterly destroyed the reputation of his imstru-
ment, (which could always have spoken for itself,) instead of
which, we, with the greatest tenderness, opened the eyes of his
unfortunate offspring, and made them see very well. |

C. One of the quadruple combinations of this set was beau-
tifully perfect; the sextuple system was well corrected for sphe-
rical aberration, but rather over-corrected in point of dispersion.
I certainly do not think this defect of much consequence. It
merely causes the outline of a transparent object to be of a
bluish colour, instead of its natural tint. Under-correction gives
an outline of red and orange, which I utterly detest. Neverthe-
less, in order that a false doctrine may not be deduced from this
concession, which might be found exceedingly comfortable and
convenient to slovenly opticians, viz. that if the spherical aber-

‘

* and on the Memoir of Euler. > © 239

ration is well corrected, it is of small moment whether the chro-
Matic is so or not.—I must observe that the necessity for re-
moving dispersion is never so sensible as when the spherical has
been withdrawn ; for the latter covers and conceals the former,
just as the taste of one sapid substance, will-cover that of: an-
other, or, speaking accurately, as a fog oomennis the tints of a
landscape.

This set of object-glasses was exquisitely centered and nd.
justed.

D. Proof-objects have hems wretchedly abused by dishonest
tradesmen, owing to the vast difference of facility of resolution
which exists between specimens of the same kind, or nearly. so,
so that it has been well observed by Mr Lister, that the only
safe way to determine between two microscopes, is to apply the
same identical scale to both, under the same circumstances.

In illustration of this position, I shall observe, that I have
seen a specimen of French podura of no more difficult resolu-
tion than the menelaus; yet not to be distinguished from. the
difficult English podura, by its outward and visible character.
Even among the most difficult English podura there are fre-
quently a few large coarse scales to be found of very easy de-
monstration. The same discrepancy is found among the other
kinds of lined objects.

KE. See my paper on monochromatic light.

F. This is a very excellent set of object- glasses for practical
purposes, but neither of the sextuple compositions are so per-
fect as that which I shall next describe ; in order to arrive at
perfection, it will, I believe, be found necessary to have fixed
combinations. My idea of a perfect achromatic microscope
would be this, it should have only one achromatic eye-piece,
and that to be as shallow as possible, all the different powers
to be obtained. by changing the object-glasses of which there
should be, if only of the double kind, about half a dozen fixed
compositions or systems, ranging from two inches focus to the
utmost shortness consistent with perfection ; in short, the in-
strument would be pretty much like a compound: microscope |
of the old plan, furnished with achromatic systems of iki
glasses.

_ G. This set is about ,'5th of an inch focus, and has an an-

NEW SERIES, VOL. V. NO. I. OCTOBER 1831. Q

- ;
240 Dr Goring’s Remarks on M. Chevaliers Paper,
gular aperture of fifty degrees or thereabouts. Each of its com-
ponent lenses has some defect or another, which renders it unfit.
to act alone, or, in short, in any other manner than.combined
with the other two in the required order. The composition of
the three is, however, without fault or blemish of any kind, it.
cannot be said that there is any defect of centering or adjust-
ment, or any spherical or chromatic aberration, which ‘the eye
at least can detect; for that tendency to over-correction, both
for sphericity and dispersion, which seems irremediable in ob-
ject-glasses, embracing a very large pencil, is on this very mi-
nute scale wholly insensible, and so of course is the secondary
spectrum, so that M. Chevalier has here contradicted himself
by his own works, and produced that ultimatum which he insists
upon being unattainable. Moreover the oblique pencil is well
corrected. NT ha
It will be recollected that the aberrations of an ordinary un-
corrected object-glass of the same focus and aperture are’ faint
in comparison to those of longer foci, taking in a peneil of the
same size, so that acommon lens of ;5th of an inch focus, and
an aperture of thirty-six degrees, has the power (though with
much confusion,) of showing all those lined objects which an
achromatic of. one inch focus and an equal aperture can show
when raised to the same power, (Jet us suppose .;,th of an
inch). Therefore, if we wish to make a fair comparison between
the performance of an achromatic object-glass and a common
one, both should be of the same focus and angular aperture.
Though we may in some measure make a common compound
microscope compete with an achromatic one, having an object-
glass of long focus, by making that of the former very deep ;
yet when we get a perfect achromatic system of ,},th of an inch
focus, its superiority over a common jth of an thal becomes
nearly as manifest as that of an achromatic of one inely focus
over a common one inch one. | M
M. Chevalier has now, I think, arrived at the shied ese
which it will be possible to use wpon opaque objects. With re-
gard to the performance of this system, I think it enough to
say, that I have seen with it the two sets of diagonal lines on
the true difficult Pieris brassice, which I never saw before,
with any sort of certainty, with any achromatic object-glass ;

and on the Memoir of Euler... 241

yet not so. mie wi ie as I have seen them with Mr
Cuthbert’s ths of an inch metals, having an aperture of
ths of an inch; a striking proof, in my mind, of the supe-
riority of the reflecting principle, for the advantage in point
of power is three to one in favour of the refractor. However,

every artist will eternally insist that there is nothing equal to

his own leather, be it what it may. This set comes up to a

power equal to that of a ~;th of an inch lens without any for-

cing, and the vision is, with this amplification, certainly equal in

point of distinctness to that of any single or compound mag-

nifier,.and superior in the article of achromatism, field of view,

&c. The said set of object-glasses are in the possession of
Mr Pritchard, Picket Street, Strand.

H. I have lately received an intimation from M. Chevalier;
that he expects to effect a still greater reduction of the focus
of his object-glasses, by forming an achromatic system, by
combining two over-corrected object-glasses with a common
lens, according to the plan laid down by me in my paper on
facilitating the manufacture of engyscopic objectives. See this
Journal, No, vi. P- 244.

I. It is not my intention to enter into any controversy here
concerning the invention of achromatic object-glasses, which
being a very valuable one, has of course plenty of fathers to
it. It must be obvious, on the most superficial consideration,
that the object-glasses of microscopes are merely modifications
ef those of telescopes, therefore, there was nothing to be in-
vented about them. :

We are perpetually annoyed with new applications and
adaptations of old things, which are falsely termed new inven-
tions; thus it is customary to style a steam-boat, a steam-car-
riage, steam-gun, a cotton-mill, &c. new inventions, though:
they are only so many ingenious and valuable applications of
a steam-engine, highly creditable to those who have brought
them imto use.

Kuler is undoubtedly the original adapter be deinallaatis ob-
ject-glasses to the compound microscope. ‘heir use as mag-
nifiers, as eye-pieces, as well as for forming the image of the
solar microscope, was, I think, originally pointed out by my-
self in the first treatise I wrote upon them; but all these ap-

Y

242 Dr Goring’s Remarks on M. Chevaher’s Paper,

plications are so very obvious, that the credit, (if any,) which
may be attached to them, is scarcely worth having.

K. It would be easy to bring forward a considerable mass
of evidence to prove that achromatic object-glasses for micro- —
scopes had been repeatedly tried and abandoned in this coun-
try many years back ; a circumstance of which I was perfect- —
ly aware before I employed Mr W. Tulley to construct them
for me. Thus, in Adams on the microscope, a work publish-
ed in 1787, is the following passage: “ Achromatic glasses.
How far this invention is applicable to the improvement of
microscopes has not yet been ascertained; and, indeed, from
some few trials made, there is reason for supposing they can-
not be successfully applied to microscopes with high powers ;
so that this improvement is yet a destderatwm in the construc-
tion of microscopes, and they may be considered as being yet
far from their ultimate degree of perfection.” —Tp. 48, 49.

In May 1807, the celebrated Mr Troughton employed Mr
W. Tulley to make him a dozen achromatics of oné inch focus
for his astronomical circles, but rejected them as worse than
common lenses, on account, of their bad execution. It can,
moreover, be most distinctly proved, that Mr Dollond has had
a triple achromatic of one inch focus kicking about his shop
for more than thirty years back. The reason that none of thése
object-glasses were brought to perfection was because proof-
objects, were not discovered at the time of their fabrication, so
that opticians had no certain object to aim at. 1am convin-
ced that the utility of achromatics would never have been re-
cognized to this day; nor would they, except by chance, have
been constructed in an effective manner, had it not been for
my own discovery of the peculiar property of the lined ob-
jects. In confirmation of which, I may observe, that any dis-
covery of fresh proofs of still greater difficulty than those pre- _
viously known, has been invariably found to produce fresh
improvements in object-glasses and microscopes in general.
Thus, when the brassica and podura were discovered ; —
cians immediately found themselves under the necessity of
extending the angular aperture of their object-glasses, and of
combining two or three together, in order ‘to give them the

power of discerning the lines on these objects; because it was

and on the Memoir of Euler. 243

found no single object-glass could embrace a pencil of light of
sufficient size to render them visible. I appeal to opticians
whether telescopes have not been greatly improved since it has
become the fashion to try them on double stars. Formerly they
were considered good if they showed the moon and the planets
well; but a much greater degree of perfection is now required
of them, because hay have to deal with what are to them
proof-objects.

Had we remained to this day ignorant of proof-objects, op-
ticians might certainly have made achromatic object-glasses for
microscopes ; but they would have been the poorest things ima-
ginable, for the value of a large aperture would never have
been felt, and when that of achromatics is reduced to a level
with that commonly employed in the old compounds, their
value or superior utility can hardly be appreciated, because
the aberration of the common instruments is in this state in-
visible to ordinary eyes.

When I first took the subject | in hand, I mentioned it to
perhaps the first theoretical optician of which this country can
boast. He was, moreover, in the habit of observing with the
microscope, and the remark he made me was this: “* Why, I
always thought compound microscopes were achromatic,” To
which I answered, ‘* that they might appear achromatic un-
der certain circumstances, provided the ee had an
exceedingly small aperture, as was generally the case.” Now,
if such a man could form such an opinion, what may be éx-
pected from the vulgar ? |

L. This is the date I think of the first effective double-object —
glass. ‘Though the error of the oblique pencil is so great in a
glass of this description, if it has a sufficient aperture to show
proof-objects, that all objects out of the pale of a few degrees
from the centre of the field of view would be completely con-
fused, it is this defect which renders a double object-glass un- -
fit to be used, except in combination, unless its aperture is very
much reduced. BTR

M. In the autumn of 1823, Mr W. Tulley commenced his
labours on my account, and about the 1st of March 1824, pro-
duced an object-glass of 0.333 focus and 0.2 of aperture ; for
from the very beginning Tulley always aimed at the utmost pos-

244 Dr Goring’s Remarks on M. Chevalier’s Paper,

sible reduction of the focus. The next he made for me was
of two-tenths of an inch focus, and 0.1 of aperture. _The 0.933
was made afterwards at the suggestion of Mr Lister.

The said 0.333 focus object-glass was, I rather think, the
first effective one which chanced to be made at least by design
and principle, for it was bottomed on proof-objects previously
discovered with the single miscroscope. However, I shall leave
it to posterity to determine this point. The triple form is evi-
dently that adapted to the miscroscope 5 for one alone well ex-
ecuted is capable of receiving an aperture quite sufficient for
all ordinary purposes, and also for shewing the majority of the
lined objects, which advantages it combines with a good cor-
rection of the oblique pencil. We do not want to be eternal.
ly looking at proof-objects any more than the astronomer does
to be perpetually observing double stars and clusters of diffi- —
cult resolution. A telescope may be a very good and valu:
able instrument, though it has not the power of showing al
the latter bodies ; and so may a miscroscope, though it should
not be able to exhibit the more difficult lined objects.

T certainly do not like triple object-glasses in combination.
There is a dimness in the vision of opaque objects caused
» by the loss of light from their numerous surfaces ; but if they
could be made thin, and with their inner surfaces in contact
and cemented together, two of them would evidently be clearer
than three double ones, (because two additional surfaces would
be obliterated,) and quite as effective. Moreover, I am pretty
sure that a triple object-glass highly over-corrected for spheri-
city and dispersion might be combined with a common lens for _
the purpose of increasing its power and angular aperture and
improving its oblique pencils, and be equal in effect to two
triple object-glasses of equivalent foci, with a far srentes ptm:
plicity of construction. £ 3

The practice of piling Mount Pelion on Mount Ossa A
never be resorted to, unless in a case of great nesses me a
real artist. ve

N. What.a compliment is it to the reflecting engyacand: to
construct an achromatic refractor as nearly as possible in its
form, by directing the rays at right angles by means of a rec.
tangular prism; and this too purely on, the ground of the at-

and on the Memoirof Euler. 245

tainment of a more commodious method of observation. .. I cer-
_ tainly have seen many observers who prefer this form of the
refracting instrument, though I do not admire it myself.

| Restle on Euler's Memoir

O. Ls page 6 of the first article of Euler’s memoir, “ Des
verres objectifs delivrés de toute confusion,” speaking of tri.
ple achromatic object-glasses, he says, ‘* they might also serve
to improve miscroscopes by making them as small as possible,
but then you must reverse the order of the lenses, by turning
the third towards the object in its focus. ‘To succeed better in
the-construction of them, it will be advisable to inclose each
lens in a little cell, so that the distance between them may be a
little varied, in order to discover, by experiment, the best dis-
position of the glasses relative to each other, for. it is almost im-
posible to execute in practice all the prescribed measures, but
a little change in their distance will be sufficient to remedy
this defect.” .

When I consider this passage in conjunction aie the curves
given by Euler, I am almost certain that he had no other
idea about the object-glass of an engyscope, but that it was
to be that of a very small telescope of a larger angle of aper-
ture than usual, reversed or inverted. The same. notion I
have found to prevail among other mathematicians, with whom
I have conyersed on the subject; and, I must confess that in
theory the doctrine seems plausible enough, for when a tele-
scope, is, made to act upon a near object, say forty or fifty feet
distant, (and be it observed that opticians like to try them
best in this way, as they can be more certain of their quality
than when made to perform with more parallel rays,) there is '
not a greater disproportion between the length of these con-
jugate foci than takes place in an engyscope, therefore, the
rule ought, at all events, to be good enough for practical pur-
‘poses; nevertheless, I am convinced myself that it is far too
_rude and coarse; no optician could, I am sure, make a triple
object-glass for an engyscope by it to please the most ordi-
nary customer, though it might do well enough for a-mere
magnifier.

246 Dr Goring’s Remarks on M. Chevalier’s Paper,

I suppose, if it is conceded that the object-glass of a small
telescope should, when turned the wrong way, constitute that
of an engyscope, the object-glass of the latter must also, when
turned the wrong way, form that of a telescope. Now we:
will screw this doctrine up to the sticking-place, and see if it
will be found wanting or not when made to stand the brunt
of facts.

The following are the results of trials with a oth ‘tiple-e en-
gyscopic object-glass used as a teleseope. I must premise,
that the said oat pea is achromatic and aplanatic, with an
aperture of about ,°; of an inch, used as'a microscope, but if.
the aperture is greater, the spherical aberration begins topre-
ponderate in the concave. If the whole aperture ;%5 1s em-
ployed, it is very violent in the concave, and there is:also: a
tendency to over-correction in point of colour. I mounted
the said object-glass as a telescope, with an Huygenian eye- —
piece, which made it magnify nearly four times, and reversed ©
the order of its lenses.’ : riot ost ginent

Whole aperture.—Spherical aberration very ‘violent inthe
convex. ‘There seems to be no difference wine way it is turn-
ed towards = object. , | )

Cut off to rb: do. do. © See AOS

Cut off to ro the same but weaker. be RMT

Cut off to ,',, spherical aberration, the same way as befor; ,
whether the object-glass is inverted or not. A little under cor-
rection in point of colour, now becomes manifest. This was be-
fore corrected by the sttong spherical aberration in the convex
lenses, which is now, by the reduction of the 9% consi-
derably weakened in intensity. ~ Si a 8

Aperture ,',.—Aberration greatly reduced, but still hie:

same way as before; that of a plano-convex lens of the same ~

focus and aperture, with its covered side towards the object, ee
scarce to be distinguished now from that of the achromatic.

I may observe, that all the Gripe achromatics I have ever
tried give much the same results. The curves of the 75 ob- —
ject-glass are, ei OS

Radius of Ist surface, — 0.825 } oe ‘id
Od, 0.525 | convex, (Crown)

and on the Memoir of Euler. — 24:7

Radius of 3d_ surface,

99 concave, (Flint) |

4th,
6 oor convex, (Dutch Plate)
Specific gravity of crown, 2.527 |
Thickness of do. 0.15
Specific gravity of flint, 3.627 \
Thickness of do. 0.164
Specific gravity of Dutch, 2.519
Thickness of do. 0.175

pom mathematician may see that there is in this object-glass
a vast excess of aberration in the convex lenses, beyond what
would be required in a telescope, which ever way the rays pass
through the lenses.

I once procured the object-glass of a small perspective of
little more than four inches focus, and somewhat more than
an inch of aperture, and converted it into the object-glass of a
long engyscope by reversing it. I regret that I did not make
notes of my observations with it,.as I cannot now obtain it
again; I only recollect that i¢ did not answer at all, and was
not even achromatic used in this way. If I can rely on my
memory, this object-glass, used in its natural way asa tele-
scope, had an excess of aberration in its convex lenses, (at least
with its whole aperture,)—a circumstance which should have
operated much in its favour. )

I conceive, therefore, that Euler hes done little or nothing

beyond pointing out the application of achromatic glasses to
form the images of engyscopes, both because he has selected
an angle of aperture much too small for efficiency even on ob-
jects not of lined kind, and because his system of reversing the
order of the curves of an achromatic, in order to adapt it to .
diverging rays, will be found utterly inadequate to the pur-
pose. The affair will not be got over so easily I am sure, but ..
will prove a confounded tough job for the proudest mathema-
tician in Europe. The talents of Euler were perhaps little .
inferior to those of any man living or dead. Had he taken up
the subject in the right point of view he would doubtless have
succeeded.

A double object-glass agrees rather better with his theory

°
248 Dr Goring’s Remarks on M. Chevalier’s Paper.

than a triple one, that is to say, it performs better wpon paral-

lel rays when inverted than it does when its concave lens is
presented to them to form a telescope; but to obtain this ap-

proximation it must be very thin, and have a very small. ener

ture, and is even then a long way off from its true figure. ch
As metals are very simple in their action compared with

achromatic glasses, I always like to put a case with regard to ‘

them in order to settle any theoretical point. Accordingly, , I

have tried a set of beautifully perfect metals belonging | to an —

Amician reflecting engyscope, inverted as miniature Newto-
nian telescopes, and found their figure a great deal too spheri-
cal for parallel rays,. vr line of the large — “3
aperture.

Had Eulet’s theory been aoa they ought to have ands

formed very well as minute’ telescopes, because their figure
should, in this case, have been parabolical, instead of which
it is much nearer the sphere, and, as I presume, ‘elliptical,
which harmonizes. perfectly with the other trials ; for the dif-
ference between the ellipse and the parabola-is equivalent to
that between the condition of an object-glass perfect in : its ac-
tion on parallel rays, and another which has too much spheri-
cal aberration in its convex lenses to be so. 'The said metals
are, however, not so much out in point of figure as a triple ob-
ject-glass is, but about as much as a double one, as far as:I

can guess. The theory of achromatic glasses for diverging f

rays, is then, I am persuaded, an untried field, in which no

mathematician has as yet distinguished himself.* shall pro- _

bably be told that a theory would be of no use if we had it,
because artists would not work to it. This is true with regard

to the more minute glasses; but very beautiful and useful en-
gyscopes may be made on a large scale, having object-glasses

of so long a focus as four and even six inches, which also act
very strikingly in the solar microscope; and a theory -—

* Money is said to make every thing go; to be at the bottom of ever
thing; and to purchase every thing, (if i in sufficient quantity.) | Thus a
men and all women have their price.’ When I get rich I shall try if ‘the
offer of a good:round ‘sum will stimulate the men of numbers and quanti-
ties to undertake the theory of a thick aplanatic object-glass for diverging

rays.
3

.

Mr Lister: on Achromatic compound Microscopes. 249

always be tried and. executed: on: this scale, which would not
strain the powers of a real artist too much:

- The principal opticians im Europe have made/ achromatic
object-glasses for engyscopes for some years, and) are immea-
surably in advance of the mathematicians on this.subject. 1f
the latter gentlemen do not choose to turn their attention to
it, I presume they will be content to retire into the shade ; to
abate somewhat of their magnificent pretensions to infallibility
and exactitude; and to admit that for once analysis has been
beaten by experiment, at least in the pitiful, pimping, insig-
nificant, article of the object-glass of a compound microscope,
which being such a mere trifle cannot of course reflect any dis-

grace on their incapacity to handle it.

** tractata queeque nitescere posse
** Desperant, relinquunt.”

LamBETH, June 30, 1831.

‘Arr. X.—On some properties in Achromatic Olject-glasses

applicable to the improvement of the Microscope. By Jo-
sEPH JACKSON ListER, Esq. (Concluded from No. ix. page
180.)

Or several purposes to which the particulars ‘just given seem
applicable, I must at present confine myself to the most ob-
vious one. They furnish the means of destroying with the
utmost ease both aberrations m a large focal pencil, and of thus
surmounting what has been hitherto the chief obstacle to the
perfection of the microscope. And when it is considered that
the curves of its diminutive object-glasses have required to’ be
at least as exactly proportioned as those of a large telescope,
to give the image of a bright pomt equally sharp and colour.
less, and that any change made to correct one aberration was
liable to disturb the other, some idea may be formed of what
the amount of that obstacle must have been. It will however
be evident, that if any object-glass i is but made achromatic,
with its lenses truly worked and cemented so that their axes.
coincide, it may with certainty be connected with another pos-
sessing the same ‘requisites and of suitable focus, so that the

250 Mr Lister on the improvement of the

combination shall be free from spherical error also in the cen=
tre of its field. For this the rays have only to be received by the
front glass B, Fig. 6, Plate I. from its shorter aplanatic focus f,
and transmitted in the direction of the longer correct pencil f A
of the other glass A. It is desirable that the latter pencil should
neither converge to a very short focus, nor be more than very
slightly, if at all, divergent; and a little attention at first to —
the kind of glass used, wil] keep it within this range, the denser
flint being suited to the glasses of shorter focus and —_
- angle of aperture.

The adjustment for the microscope is then perfected, if ne.
cessary, by slightly varyimg the distance between the object-
glasses ; and after that is done, the length of the tube which
carries the eye-pieces may be altered greatly without disturb-
ing the correction; opposite errors which balance each other
being produced by the change.

If the two glasses, which in the diagram are drawn as at
some distance apart, are brought nearer together, (if the place
of A for instance, is carried to the dotted figure,) the rays
transmitted by B in the direction of the longer aplanatic pen-
cil of A, will plainly be derived from some point (x) more dis-
‘tant than f”, and lying between the aplanatic foci of B; there-
fore (according to what has been stated) this glass, and conse-
quently the combination, will then be spherically over-cor-
rected. If on the other hand the distance between A and B
is increased, the opposite effects are of course produced. |

In combining several glasses together, it is often convenient
to transmit an under-corrected pencil from the front glass,
and to counteract its error by over-correction in the middle one.

Slight errors in colour may in the same manner be destroy-
ed by opposite ones; and on the principles described, we not
only acquire fine correction for the central ray, but by the op
posite effects at the two foci on the transverse pencil, all coma
can be destroyed, and the whole field rendered beau lony flat
and. distinct. /

The occurrence of two good combinations among the nume-
rous ones of Utzschneider’s glasses will now appear only what
might be expected; and more are to be obtained from them
by varying the distance of the glasses from each other.

Achromatic compound Microscope. B61

I have very lately seen one of Chevalier’s combinations of
three glasses, each about 0.4 inch in focus, inferior indeed to
these, and of contracted aperture, but which I ought to no-
tice because its image is pretty well corrected with the glasses
in the order given to them by the maker. At the same time, I
do not suppose him to be acquainted with the principle which
constitutes the key to the effect ; otherwise he would hardly
have failed to apply it more effectually.

The achromatic meniscus that has been described, enters
well into combination, and may perhaps be useful as the front
glass of three, but its power is small in proportion to. its
curves. It admits too of being cemented at the back of an
achromatic plano-convex ; and they may make together a
powerful compound glass to go before another.

Though the plano-concave form has been proposed for the
flint lens, in the larger-glasses it nest perhaps occasionally be
relinquished with benefit.

Some attention has yet to be given to obtain the best effect
from combination; so that with the largest pencil that may be
- found desirable, and sufficient cleat- space before the front of
the glass, the field may be aplanatic, and the focus»short. Al-
ready, however, the three first plano-convex glasses that have
been made for me by Tulley, only for preliminary experiments,
the shortest of them of 0.7 inch focus, have produced at an
aperture of 50°, the most distinct microscopic vision that I
have yet met with; and I anticipate no serious impediment to
the carrying defining power much farther.

These statements are intended only as a notice, for practi-
cal purposes and wholly detached from theory, of facts that
have been in part very recently ascertained. In investigating
them I have depended chiefly on magnified measurements and
diagrams, which, though not strictly correct, may perhaps be
as well adapted as other far more exact but difficult’methods,
for constructing the minute and complex object-glass of a mi-
croscope. It is to this that the observations made particular-
ly apply ; and should they bring more within reach than pre-
viously, the requisites which have been enumerated, I trust
they may not be unacceptable to the enlightened optician ; es-

> ‘
252 (Mr Laidlaw’s actownt of the Aurora Borealis

pecially if in this: department he unite, like Tulley, the eal ;
of the amateur with the skill‘of the superior artist. .

I intend soon to put to the test of experiment, wiscntlay
not the principle of the two aplanatic “pencils may be applied
to telescopes, in cases m which it ‘is requisite to restrict their
length, so as to enlarge their aperture with a corresponding
increase of light and distinctness. In the meantime, it would
give me pleasure to see that principle demonstrated, if it de-
serve it, by some abler hand than mine, and treated in a more
. Figorous ‘manner than my own limited acquaintance ie ma-
thematical science qualifies:me to undertake.

(Note A.) The blue down of the Menelaus and the wiilie
of the Cabbage Butterfly (Morpho Menelaus and Pieris Bras-
sicee) well deserve ‘the place they have acquired as standard
tests, especially on account of the respective characters of their
transverse tracings. “Some of the small oval ‘scales from ‘the
body of the Twenty.plumed Moth (Alucita ‘hexadactyla) are
among the closest and most elegant in their lines that I have ©
seen ; others are very easily resolvable, and the down has such
diversity of form as often ‘to‘afford within:a short space a ready
variety of excellent tests. . The same is to be said of the scales
of Podura plumbea, of which all are difficult, and some ‘seem ~
to defy all powers of definition.

It may be observed, that with most objects there is sl
difference between individual specimens of the same kind, that

in general the only safe way to determine between two good

microscopes, is to apply the same specimen to: both, under the —
same circumstances of power and light.—Phil. rans. 1830.

Arr. XI,—Account of the dhesieni Borealis seen in Rowburgh-
shire on the 5th of October 1830. By Mr W. Larpiaw,,

Kaeside.

Own Friday evening, the 17th September, an uncommon form
of the aurora borealis was observed all over the country. It
was in the shape of a luminous white arch, and stretched from
W. by S., to E. by N. nearly, ending on the E. in a pencil.
formed point, and was accompanied by pale streamers i the

scen in Roxburghshire en the 5th of October 1830. 253

north horizon; and grape visible from” twonty, to oC .
minutes.

This evening, (October 5,) I was called to observe an ap-
pearance that seemed at first to be nearly similar, though it
was more bright and better defined. When first'seen it passed
exactly overhead, and in a direction perhaps nearly the same
as the former; it was very bright, and white on the N. edge, :
and better defined than on the S., on .which side it in some
parts shaded off into the sky. . On the west end it sunk bright
below the horizon, but on the east, where it approached the
moon, it ended like the former in a tail or brush-shaped point,
before it reached the horizon,—perhaps about 20° above it.

“Having no instrument to measure the breadth, I compared.
it with the distances of some stars, and found it equal to the
longest-diagonal of the square of the Great Bear,—wider in
the E. and narrower in the W. After looking at it occasion- |
ally for about twenty minutes, I began to be aware that the
arch was making a progress towards the south, aud had already
gone over a space equal to its own breadth. | I remarked like-
wise; that its extremities were comparatively stationary ; or that
~ jt revolved on its horizontal diameter, and at thirty minutes after.
eight, the arch through which it moved was, as near as I could
judge by the eye, equal to three times its breadth. I now re-
gretted still more the want of an instrument to measure angles ;
for, while lying upon my back to observe the curvature, I no-
ticed that the bearing of the extremities was not due K. and
W..; but that a line from the Pole star formed an acute angle
with the eastern half, and I began to suspect that the centre
of the arch might be the magnetic pole. At this time the
brightness began to fade, and a longitudinal fissure appeared,
in the E. quarter. At nine o’clock, the whole arch had become
broader and considerably less bright; and in a short time af-
ter it very suddenly broke up into fragments, which I soon:
observed had a motion, following one another in the line of the:
arch from E. to W. My attention. was now strongly directed
to this movement, which I never before noticed in any of these:
arches. :

The appearance which this now assumed was very interesting.
Whether it was owing to the moon being in that part of the hea-

254 Mr Laidlaw’s account of the Aurora Borealis, &c.

vens that directed my attention to the E., [am uncertain; but I
first observed that in the eastern part the separated portions or
nebulz had assumed a striated or rather crinited appearance, the
lines of each individual nebula pointing S. E., even while they
moved all westward, following one another in an order parallel
as to each other, but obliquely as to their position on the arch,
so that to a careless observer the first general form of the arch .
would: have seemed to be preserved :—only that at, and on a
little on each side of the meridian, the general continuous line |
of the arch was interrupted ; and here an interesting change
took place in the direction of the strize of the nebulee, or ra-
ther in the order in which they appeared when farther east :—
For, on crossing the meridian, they veered to the right, and form-
ed on the western part of the arch, with the striated appearance
pointing S. W. During the time that this movement continued,
coruscations were apparent, and suddenalternate disappearances.
and reappearances of the brightness, similar to what is often.
observed in the common streamers; the striated divisions not.
being always, nor throughout the whole length of the arch,
distinctly separated from each other. 'I'hese coruscations were
most apparent in the eastern quarter, although they sometimes
flashed from one end of the arch to the other, and always from
east to west. el ge ;

The motions of the striated divisions had the apparent ve- —
locity of clouds in a gale of wind, but the shifting and flashing
was similar to that of the streamers usually seen in the north.
I have since learned from two different persons, one in this
neighbourhood and the other in Liddesdale, that there were
two arches that evening, one a little: after sunset, which was
not so bright and soon disappeared ; and that the second flash-
ed out at once bright into the sky. | pe

It has since occurred to me that the motion of the striated
portions of the arch from E. to W., and which seemed so. sin-.
gular, would be best described by referring it to the motion of
a wheel with radiated teeth. The motion of such seen in per-
spective, would exactly represent the extraordinary appearance
attempted to be described. | |

‘

Mean Temperature of New York, &c. 255

Ant. XIL.—LOn the Mean Temperature of Tutrty-Four dif-
ferent places in the State of New Yi wes for 1650.

In the sixteenth No. of this Journal, ands in Nos. ui. and-v Vii.
of our New Series, we have given abstracts of the ‘*- Returns of
Meteorological Observations made to the Regents of the Uni-
versity of the State of New York for.1826, 1828, and 1829.”
_ We are now enabled to present our readers with an abstract
of the same valuable returns for 1830... These returns have
been made by no fewer than 42 academies ; but only 34 of
them are complete. |

The observations seem to have been made at the same hours
as formerly, viz. 6° a. m. 3° p. m., and an hour after sunset.

Tn No. vii. p..78, we have given the positions of the places
where observations were ooh ong in. 1829. . The following Table
contains the positions of the academies not in that it which
have made observations for 1830.

N. Lat. W. Long. Elevation

above tide,
~ Canajoharie, © : 49°53’ 74° 357 284.
“Cayuga, aurora, . 42-45 76 40 412
Cortland Homer, 3 42 38 7611 1096
Delaware, = ma 42 17 Th 54 1384
Fairfield, - af 48 6 7454 1185:

Fredonia, Chautangue Co. 42 25 79 24 °° 645:
Gouverneur High School, 44 25° 75 35. 400

Ithaca, : s 42 26 ‘76 30 417
Kinderhook, a 42°24 73 45 195
Lewiston, — - - OF Ee we (Dy RU 280
Mount-Pleasant, . 41° 7% 74 16 ,
_Plattsburg, - - 44 42 73 23 “105
Redhook, liga 42 2 3 56 tS
Rochester High School, 43 5 7745 ° 506
Union Ellesburgh, +s Me AO. Leos

In 1826 the mean temp. of ten places was 49°. 4

In 1828 the mean temp. of twenty-three places was 49.99. .
In 1829 the mean temp. of twenty-eight places was 46.45 _
In 1830 the mean temp. of thirty-four places was 48 .15

NEW SERIES, VOL. V. NO. 1f. OCTOBER 1831. R

a

‘ °
256 Mean Temperature of thirty-four different places

The following table contains the mean monthly tempera-
ture of the thirty-four places. above-mentioned, the annual
mean temperature, the annual range, and the highest. and

lowest during the year.

Jan. ‘Feb.
Albany, , 24.56 24.82
Auburn, 22.54 23.62
Cambridge, Wash. 23.73 18.'79
Canajoharie, 16.60 20.80
Canandaigua, 22.50 24.86
Cayuga, : 26.82 27.53
Cherry Valley, 19.02 20.19
Clinton, : 30.88 27.20
Delaware, x 19.49 22.71
Dutchess, ‘ 26.47 26.68
Erasmus-Hall, 28.90 30.83
Franklin, . 20.11 24.79
Fredonia, - 25.89 26.90
Hamilton, 4 19.16 21.93
Hartwick, 2 22.45 25.42
Ithaca, : 25.89 29.75
Kinderhook, 292.01 22.59
Kingston, : 25.28 25.11
Lansingburgh, 22.53 23.36
Lowville, ‘ 15.35 1'7.64
Middlebury, 23.16 26.51
Montgomery, 26.98 27.29
Newburgh, 25.68 24.48
North Salem, 26.87 25.54
Oxford, ‘ 19.66 23.40
Pompey, -~ + 18.13 21.82
Redhook, .- 23.44, 23.94
Rochester H. School 22.38 25.43
St Lawrence, 13.01 18.24
Union, - 19.89 24.35
Union- Hall, 29.21 28.85
Utica, 20.08 22.26
Washington, 19.64. 19.73

Seminary of G&OC 19 37. 20.87

March.
38.05
$4.55
34.52
31.78
35.20
36.56
31.17
37.97
33.62
38.94
40.84
33.69
38.23
31.51
35.85
37.86
37.17

40.38
36.15
31.20
36.01

39.00
37.00
38.65
34.30
$2.54
37.18
35.40
31.45
36.25
39.31

33.95
33.18
33.20

April.
56.02
50.63
49.69
50.17
52.02
49.18
48.56
45.94
45.86
55.68
50.96
48.71
53.35
50.38
51.25
52,89
51.71
56.46
54.45
49.76
50.79
53.93

50.50.

51.22
48,84
48.75
51.10
54,34
51.10
55.90
50.29
51.31
49.37
49.73

May.
59.27
53.90
54.19
56.14
53.25

53.61

53.92
51.56
50.81
62.33
58.16
52.35
56.21
52.08
52.75

55.98

54.47
61.76

58.46
52.91
52.86

58.71
57.82

57A3.

54.59
51.56

52.62.
54.68.

53.65.
51.47
56.15
53.13
51.09
51.88

June.
65.98
62.06

59.57

63.60
63.42
63.08
61.27
63.02
57.88
69.83
67.35
61.14

62.18
60.10

59.65

6415

63.58

60.00

61.05

68.58
65.11

65.25

in the State of New York for 1880.

Albany,, ~
Auburn); -
Cambridge, Wash.
Canajoharie,
Canandaigua,
Cayuga, -
Cherry-Valley,
Clinton, -
Delaware, F
Dutchess, ~
Erasmus-Hall,
Franklin; ¥
Fredonia, f
Hamilton, a
Hartwick, =
Ithaca, -
Kinderhook,
Kingston, ==
Lansingburgh,
Lowville, es
- Middlebury,
Montgomery,
Newburgh,
North Salem,
Oxford, é
“Pompeys ™
Redhook, 5

July.

73.86
71.41
70.73
72.84
71.83
69.97
70.32
7047
71.08
TTT
75.26
73.12
73.57
69.68
69.32
73.33
72.36
73.39
73.76
70.47
70.23

"5.52

72.37
71.85
70.83
69.62
70.12

Rochester H. School 73.44

St Lawrence,
Union, t
Union-Hall,
Utiea, * .
Washington,

70.28
67.59
74.16
70.26
70.18

Seminary of G&OC 69.73

Aug.
70.52
65.75

67.57,

67.77
65.49
67.08
62.41
69.17
66.95
13.87
710.66
64.65
67.76
65.34
64.26
66.16
69.00
71.51

71.01

64.42
65.30
14.52
69.47
69.11
64.85
63.72.
712.34
68.87
65.51

59.49
70.12
64.75
65.46
63.30

Sept.
61.82
57.52
63.40
57.71
56.44
60.32
57.07
61.40.
59.14
64.37
63.47
56.69
58.71
55.80
56.96
58.88
59.46
62.10
60.68
54.75
58.38
63.48
59.93
60.64
58.60
54.72
62.44
59.66
55.72
54.15
57.63
56.22
56.90
55.48

Oct.
52.39
50.89

52.30 |

47.88
51.58
56.60
47.79
58.71

51.23
55.36
55.28
48.62
52.88
50.03
48.21
51.78
51.25
52.91

51.35
48.35
52.10
57.15
59 01
51.04
48.08
47.23
51.98
54.99
47.07

46.59
53.96
48.25
46.25

49.51 >

258 Mean Temperature of thirty-four different places

Ann. Mean. Highest.

Albany, ; 50.65

Auburn, > 2-Ve AT 37
Cambridge, Wash. 47.92
Canajoharie, L - 46.53
Canandaigua, - —- 48.86
Cayuga, - - 49.4°7
Cherry-Valley, 45.17
Clinton, - - 49.82
Delaware, . 44,99
Dutchess, A 52.73
Erasmus-Hall, ‘ 52.53
Franklin, ‘ 46.38
Fredonia, i a 49.57
Hamilton, 4 w 45.87
Hartwick, “ - ~ 46.68
Ithaca, . : 49.67
Kinderhook, 48.24
Kingston, “ 51.47
Lansingburgh, " 49.64:
Lowville, “ 44.60
Middlebury, 2s SHPBZ
Montgomery, C 52.038
_ Newburgh, ‘ 50.25
North Salem, ‘ 49.96
Oxford, ~ . 46.55
Pompey, ¢ “ 44.68
Redhook, - “ 49.10
Rochester H. School, 49,27
St Lawrence, 2 44.58
Union, = b 45.94
Union-Hall, . 51.05
Utica, 4 - . 4644
Washington, 46.02

Seminary of G. & O. C., 45.45

97
96

93.

97
93
94
92
93
93
100
93
90
97
95
91
96
. 94
93
98
93
94
104
94
97
93
90
90

98
90.
90.

100.

Bi o',

88

et

Lowest.

—12
— 4
—25
—16
— 8

0
—22

born 3 iF

TaD

—20
—17
— 1
—l4
—13
— 20)
—33

—12
—10

—_ 54 0
—15

—1l]

—10—

asthe
—27

'—23

0

—17-

—24
22

118° 85 ~
113° 60°
101 55
O4.5r ’ *
14992?
91 51
LIO: walght
120: 78%
89 54
97 60
106 61
WS 4
108 77
108 "70
106 71
118° 7%
126! FY

101 67

104° 57
111 69°
108° 70°
101° 64
100 69

103 55).

117 73
113097)
100 55.
107 85
112%

YM isco

The following Table shows the quantity of rain and show
which fell in the state of New York in 1830. :

in the State of New York for 1830.0 -. 259

In. boi pp,
Albany, “ 41.85 Kingston, “ 40.15
Auburn, "i 37.88 Lansingburgh, - » 40.67
Cambridge, Washington 35.10 . Lowville, - 86.66
Canandaigua, -- $6.60 Middlebury, L 38.50 |
Cayuga, ; - 37.11. Montgomery, ~ 40.99
Cherry-Valley, - 45.05 Newburgh, m8 34.83
Clinton, Sid 46.65. North Salem, P 43.37
Delaware, - - 22.55 . Oxford, 2 83.79
Dutchess, - 46.36. Pompey, - »» 80.06
Erasmus-Hall, - .53.47. Redhook, N - 43.00
Franklin, - 36.15 . Rochester High School, 34.94
Fredonia, - 33.93 Union, ¥ 26.09
Hamilton, terre 42.71. Union-Hall, 43.32
Hartwick, Z 41-59 Utica, - 46.19
Hudson, ‘ 39.77. Seminary Gen. and
Ithaca, —_—- 35.61 Oneida Con. ’ 41.59
Kinderhook, E 36.92
; ; ‘ Inches.
In 1826 the mean rain: of nine places was 36.34
In 1828 the mean rain of twenty-five places was 36.74
Tn 1829 the mean rain of twenty-five places was 34.88

In 1830 the mean rain of thirty-two places was 38.86

~ Mean, 36.70

| MiscELLANEOUS OBSERVATIONS.

Aurora Borealis noticed.

January 24, at Canajoharie academy, Utica.

Jan. 27, at Lowville.

Feb. 16, at Pompey.

Feb. 18, at Pompey, St Lawrence, Utica, Cazenovia.

Feb. 19, Albany, Canajoharie, Delaware, Kinderhook,
North- Salem, Pompey, Utica.

Feb. 23, at. Canajoharie. Segment large and. |uminous.
Light in the west at half-past 8, like egeighe: Lowville, North
Salem, Utica.

March 15, at Albany, Canajoharie. Exhibiting the appear- _
ance of day break half an hour before sunrise: Franklin, Low-

>
260 Mean Temperature of dherignfour different places
ville, Middlebury, Pompey, St Lawrence. Very brine iinet

Cazenovia. i
March 16, Union. ; areas A
March 28, Albany, Pompey. ding’
March 31, at 10 v. m. a single column of light,.a little west

of north, extending up at right angles with the horizon, and

subtending an angle of about 25 degrees, Franklin... >

Apmil 15, at Albany, Lowville, Pompey, St Lawrence, Utica:

April 19, from 8 p. m. tll nearly midnight, the whole north-
ern horizon presented at times, streams of light, which rose,
enlarged and disappeared in succession, sometimes extending
almost to the zenith; at others, rising only a few degrees,and
usually succeeded by a dark hazy appearance. . The light from
this source was sometimes as much as the moon affords, three
or four days after conjunction, Auburn. Very brilliant: Cam-
bridge, (Washington,) Canajoharie, Cayuga. At 9 PeMela
broad column of light, perpendicular. to the horizon, and:éx-
tending up about 45 degrees; the whole was so brilliant that
the shadows of objects were distinctly seen on the north side
of buildings. About midnight it was still more brilliant:

Franklin. Brilliant: Hudson, Lansingburgh. | Nearly one-

third of the horizon illuminated during the night. | The thigh+

est part of the illuminated segment extending to the height of

45 degrees; lively coruscations and various hues of great

beauty especially a reddish tinge of vast extent, which ap-

peared at 9o’clock: Lowville. Very brilliant: Oxford, Pom-

pey, Rochester, Union, Cazenovia. Very beautiful mith ee

coruscations : Utica. bs
April 20, brilliant: Cayuga, Delaware, Kindeshook.. T,
April 21, at Canajoharie. | tak
April 25, at Rochester. YG dE, dat
April 28, at Lowville. La
May 2, brilliant, 40 degrees above the horizon; 8 P.M

Lewiston, St Lawrence. é (sno
May 4, at 10 P.M. at Auburn, Edoiiaebargh, Lossille
Oxford, Pompey, St Lawrence. Very wide Utica. u idgil

May 9, at, Canajoharie, Hartwick.
May 10, at Kinderhook. — Sf dowel
May 11, at St‘ Lawrence. c rah

in the State of New York, for 1830. 261

May 13, at Delaware.

May 14, at Canajoharie, Hartwick, beaheel | St Lawrence,
Utica.

May 15, at Delaware, Kinderhook, St Lawrence, Union,
Cazenovia. Very bright, Utica.

May 19, at Fredonia.

May 22, at Union.

June 9, at Middlebury.

June 10, between 8 and 9 rp. M. an arc across the heavens,
Albany.. Very brilliant, and continued al] night Auburn
Luminous arch: Canajoharie. Very brilliant: Erasmus-Hall,
Fredonia, Hartwick. A very splendid A. B.; the light ‘so
bright as to cast distinct shadows, Mount-Pleasant, Kinder-
hook. Very brilliant: Lewiston. Very beautiful, and extend:
ing from the east to the west and widening to i north hori-
zon: Lowville. A beautiful arch : gr i Pompey, St Law-
rence. Uncommon A. B.: Utica.

June 11, splendid arch: Dutchess, St Lawrence, Utica.

June 16, at St Lawrence.

June 17, at Hudson.

June 18, at Lewiston, Utica.

June 29, at Hartwick, Delaware.

July 7, at Lewiston.

July 14, at Albany, Canajoharie, Franklin. Bright lumi-
nous arch a little south of the zenith, from E. to W., descend- -
ing to the south: Hartwick, Delaware. At 10.oclock very
bright: Ithaca. Very brilliant: Layiepeioaneis Ibid : Lowville,
Middlebury, Union- Hall, Utica.

July 15, at Erasmus-Hall. Noticed between 8 and 12 p. u.
At first resembling a bright cloud in the form of the segnient
of a circle; the crown being about 30 degrees above the ho-
rizon, exhibiting for several hours a steady light. About 12
it rose in distinct and brilliant spires, shooting towards the
zenith, From 9 to 10 were seen occasionally, beams of light
shooting from two points, a few degrees east and west of the
luminous ‘segment, uniting and forming a belt at-right angles
with the galaxy, and resembling it in width and appearance,
except much more luminous. ‘This moved towards the south,
and after passing the zenith, separated and disappeared:? F're-
donia.

262. Mean Temperature of thirty-four different places

July 21, at Lowville. ®t ee

July 28, at Fredonia. | hf vane

August 8, at Lewiston. |

. August 10, at Pompey, Utica. te

August 11, at Franklin. rasa’)

August 12, at Auburn, Utica.

August 13, at Auburn, Hamilton.

August 19, at Pompey, Union, Cazenovia. Unqauneply :
beautiful : Utica.

August 20, at Lowville, Pompey, Cazenovia, Utica. -Onthe
evening of the 20th the Aurora Borealis presented an ial
appearance. At half-past 9 the flashes of light, apparently
proceeding from a dense cloud in the horizon, shot. up very
high in forms resembling pencils of rays. At 10, a broad arch,
resting in the horizon, in nearly the western point, rose be-
tween Arcturus and Ursa Major, and extending over the whole
heavens, a little north of the zenith, terminated about 20 de-
grees above the eastern horizon. Between this arch and the
polar star, stood a row of perpendicular columns of light, with
uniform bases, in a right line from Arcturus to the polar star.
There were sixteen pillars on the inside of the arch, and one
on the outside below Arcturus. They maintained their posi-
tion for nearly half an hour, and gradually ascending, in the
_ same regular order, grew fainter and disappeared. ‘The flashes

in the horizon still continued very light, but not distinetly de-
fined : Utica. |

Pik

August 21, at Hamilton. _ . : feored
August 25, at Lowville, St Lawrence. 1 bbw
August 26, continued all night: Auburn, Lowrie Pom.
pey, Rochester, Union, Utica. . aah
August 28, at Hartwick. t in
August 29, at Rochester. 4 eae
Sept. 5, at Rochester. ot $i
Sept. 7, low but regularly arched, not above 20 depress above
the horizon at 8 o’clock, but,by the interposition of vapour _
between the top of the arch and the horizon, forming a per-
fect segment of a circle at half past 8, two very bright lights,
extending from the top of the arch to 50 degrees: Lewiston:
Sept. 9, at Fredonia, Utica.. be bers

in the State of New York for 1830. 263.

. Sept. 10, at Utica.
Sept. 11, at St Lawrence. 3
Sept..15, at Albany. Very brilliant, in columns springing

from an arch with prismatic colours, resembling those produ-

ced by finely striated metal: Pompey- *
Sept. 16, at North-Salem.
Sept. 17, at Pompey, St Lawrence, Utica.
Oct. 5, at Utica.
- Oct. 6, at Auburn, Canajoharie. Brilliant: Lowville, North
Salem, Plattsburgh, Pompey, St Lawrence, Utica.
Oct. 7, at Auburn, Canajoharie, North Salem, Pompey, St
Lawrence, Union, Utica.
Oct. 8, North Salem.
Oct. 9, at Auburn, Fredonia.
Oct. 10, at Fredonia, Lowville.
Oct. 11, at Utica.
Oct. 13, at Hartwick.
Oct. 14, at Pompey, Utica- Very k brilliant : St Lawrence.
' Oct..15, at Lowville. )
-Oct.-16, at Lowville.
Oct-17, at Lowville, Pompey, Utica.
Oct..27, at Auburn. :
Oct. 28, at Fredonia, Pompey. Very brilliant over the
whole north, and extending to the zenith, and there having a

_ fiery red appearance. Large red belts were occasionally seen

streaming from the west, towards the zenith, and extending
in one instance nearly to the east, spanning the chord of an
arch of about 160 degrees, and about 8 or 10 Seats broad :
St Lawrence, Union.

Nov. 9; at Pompey.

Nov. 19, at Hartwick.

Nov. 20, very brilliant : Catiasididgt, Fredonia, Middle-
bury, Pompey, Utica.

Nov. 21, at Canandaigua.

Dec. 6, at Cazenovia.

Dec. 7, at Lowville.. Very brilliant : Plattsburgh, Pompey,
Utica.

Dec. 10, very brilliant: Dutchess, Hartwick, Plattsburgh.

Dec. 11, The following description gives but a faint, al-

264 Mean Tcmperature of New York, &c.

though generally correct, idea of the splendid pen
served this evening, between 9 and 10 0’clock: BS
‘‘ Karly on Saturday evening an Aurora anpedbbdtinlline
north, stretching round from seven to eight points of the com-
pass, and from nearly north-west to nearly north-east. "The
principal light was as usual in the form of'an arch, the centre
of which was directly under the north, star.\» There was’a ge-
neral suffusion of light over the arch, and extending twenty
or thirty degrees aboveit. ‘Uhe space beneath the'arch, in the
early part of the evening, was filled witha dark cloud. Atabout
half past 6 o *clock a row of bright pillars.or columns rose from
the arch, and extended to a great height above it, and some of
them nearly as high as the north star ; ‘those over the north-
western limb of the arch were ‘slightly tinged with redness,
and all the others were perfectly white. | These pillars or co-
lumns soon disappeared and were succeeded ‘by others; the
generally rose over one limb of the first arch, and gradually
extended to the other. Between six and seven o’clock, the
dark cloud beneath the arch rose and spread over a great part
of the sky, and for some time entirely obscured the Aurora.
At about eight o’clock some clouds had passed away, and a
considerable portion of the upper part of the northern sky had
become clear again, and a row of bright white pillars ’or’co-
lumns rose from or through the dark clouds beneath, and ex-
tended far beyond the north star.—These pillars or columns
remained but a short time, and the whole northern sky was
again obscured by other clouds, and so continued: through the
greater part of the night. Through the intervals between the
clouds or the thin places in them, the light of the Aurora was
frequently seen in bright white spots over ‘the northern part
of the sky. ‘The Aurora continued throughout the night, and
between three and five o’clock on: Sunday ernie the sky
had become clear and the Aurora was quite bright :” Albany. —
Very brilliant: Auburn. Do. Dutchess. Very brilliant, il-
luminating the horizon and issuing several perpendicular co-
lumns, extending in a direction towards the zenith, from 15
to 20 degrees. The appearance was not unlike that occasioned
by a very extensive conflagration in the city of New-York,
Erasmus-Hall, Hartwick. Very brilliant’: Lansingburgh,

Mr, Johnston’s Remarks on Mr Potier’s Paper. 265

Lewiston. There appeared. two ranges in the north, one above
the other, and though irregular, yet in their main direction,
- parallel, and resembling two sublime ranges of mountains with
dark sides and slight summits of immense height, from which:
the brilliant coruscations, were, by the imagination, easily con-
verted into voleanoes. In the horizon, the light extended
from the south-east, almost to the west, and the currents and
flashes of light rose from the north horizon to the zenith, and
- thence descended half way to the south horizon: Lowville,
North-Salem, Plattsburgh, Rochester. Very. brilliant: St
Lawrence, Union, Utica.

Dec. 12, very brilliant, Auburn. Do. Dutchess, Franklin,
Fredonia. Do, Ithaca, Lansingburgh, Lewiston, Middlebury,
North-Salem, Plattsburgh; Pompey, St Lawrence, Utica.

This year has been remarkable for the frequency and often
the .brilliancy of the Aurora Borealis. In every instance, so
far as observations have been made at this place, the phenome-
non has presented a dark, dense, and regularly defined cloud,
lying in the northern horizon, and extending far to the east
and west, apparently a ground-work from which the light pro-
ceeds. On some evenings this cloud is above the horizon at
the first appearance of the flashes of light ; in others it is not
visible until after the light has been observed for some hours,
and when the flashes have continued late in the night, the
cloud ascends above the horizon and the brilliancy of the light
diminishes. In one instance, on the evening of the 11th of
December, after the cloud had risen ten or fifteen degr: ees
above a clear horizon, a second cloud ‘appeared, from which
the flashes of light were distinctly seen shooting to the upper
one: Utica.’

Arr. XIII.— Remarks on Mr Potter's Paper ** on the Specific
heats of Metals.” By James F. W. Jounston, A.M. &c.
&c. Communicated by the Author.

Since the admirable experiments df Messrs Dulong and Petit
published in the An. de Chim. for 1819, it has been rendered —
extremely probable “ that the atoms of all simple’ bodies have

o
266 Mr Johnston’s Remarks on Mr Potier’s Paper

the same capacity for heat ;” and, consequently, that the pro-
duct of the atomic weight into the specific heat is in all simple
substances a constant quantity ; or SW = C, where S denotes
the specific heat, W the atomic weight, and C the constant.”

In the preceding number, (No. ix.) of this Journal, bis
75, is inserted a paper by Mr Potter, in which he professes to
give “ an exposition of some erroneous determinations of MM.
Dulong and Petit, and an examination as to the metals,” of the —
above important law. On this paper I shall take the ey ” :
making a few observations.

Mr Potter endeavoured to determine the specific fiaat of |
eight different metals, by the old method of mixing known |
weights of the metals and of-water of different temperatures,
and marking the resulting temperature of the mixture. His
results agree essentially with those of Dulong and Petit, except
in regard to the three metals, silver, gold, and bismuth, X all
which the differences are as follow : 18)

Potter. Dulong & Petit. Difference.

Specific heat of Silver, = .063. 0557 00780
Gold, = .046 © .0298 + 0162 ~
Bismuth, = .039 .0288 + .0102

These differences form the sum and substance of Mr Potter’s
paper. ‘hey are all in excess, and are the more deserving of
examination, as they represent the specific heats of gold and
bismuth as nearly one-half greater than they have hitherto been
esteemed. i

The old method adopted by Mr Potter is the easiest, but it
is liable to many sources of error, some of which are ably point- ,
ed out by Biot in the fourth volume of his T'raité de Physique.
To escape from these sources of error, Messrs Lavoisier and
Laplace invented: their calorimeter, and Messrs Dulong and -
Petit adopted the expedient of employing a small cylinder , of

silver filled with the metal to be experimented upon in the state oe

of powder. All have agreed in considering the method of. mix-
tures as incapable of yielding any precise results, and therefore
we are led, a priori, to regard these high determinations of Mr
Potter with some degree of distrust.

This distrust is increased when we inspect the results oo
ed by Mr Potter by inverse methods. These differences for

on the specific heats of Metals. 267

gold and silver, two of the metals for which he has given new,
and, as he rape ase more correct results, are as follow :

Ist Exp. 2d Exp. Difference.
Specific heat of silver, — .0601 0669 .0068
gold, = .0375 0509 0134

On comparing these differences with those given above, we find.
that Mr Potter’s two results differ nearly as much from one
another as the mean of them differs from the results of MM.
Dulong and Petit. Mr Potter adopts the mean of his two ex-
periments, supposing, fairly enough, that the methods being in-
verse, the errors are likely to have opposite signs.

But, in the materials employed by Mr Potter, we shall find,
I conceive, ample cause for rejecting, without farther hesitation, —
the specific heat assigned by him for these two metals. “ For
gold, silver, and copper,” he says, ‘‘ I employed British coins ;”
that is to say, his gold was 22 carats fine, or an alloy containing
rzth of silver or copper; and his silver contained 7.5 per cent.
of copper,—the quantities, I believe, usually found in British
coin. With these he attempted to determine the specific heats
of pure gold and silver; and because the result he obtained
differs from that of MM. Dulong and Petit, is it right in him
to denounce theirs as erroneous ? .

Rejecting these two alloys, then, there remains only the spe-
cific heat of bismuth to be considered. Mr Potter’s two expe-
riments on this metal agree closely with each other; the two
results being .0390, and .0393, while that of Dulong and Petit, -
as above stated, is .0288. , It will be necessary, therefore, to
advert to the concluding portion of Mr Potter’s paper, before
we can determine absolutely which of them is to be preferred.

It was the numerous mistakes contained in this latter part of
the paper, together with the tone improperly as well as unjust-
ly assumed towards the French philosophers, that suggested to
me the propriety of the present remarks. Admiring, as all must
do, the profound reasoning and exceeding ingenuity of Mr
Dalton, in his New System of Chemical Philosophy, Mr Pot-
ter has entered into his views not only regarding heat, but also
regarding the atomic weights of bodies, for which his book can-_
not now .be.considered. as any authority. Had Mr Potter’s
chemical reading been a little more extensive, he would neither

&
1 -
>

268 © Mr Johnston's Remarks on Mr Potter's Paper

have spoken of others so disparagingly, nor comet

so broadly. ne Py
Mr Potter thus commences his phetevations on the law ex-
pressed above by the formula SW = C. NE

*¢ However, the law as enunciated by the French philoso-
phers, that the atoms of all simple bodies have the same capa-.
city for heat, when applied to. the class of metals, holds I find.
with singular fidelity in common temperatures, excepting % in
one very remarkable case, that of silver. Whilst the ex
tion remains, the law cannot be said to. be established, cae
‘less can MM. Dulong and Petit in the least be said to have
proved their proposition, as they have taken for the atomic weights
numbers completely arbitrary, without referring either to the
opinions of chemists, or the results of analyses. Whence they
have obtained their numbers I shall now show. They. appear
to have appropriated such portions. of Berzelius’s numbers as.
suited their experiments. Thus, for bismuth they have taken
three-fourths of this number, for lead one-half, for gold one-half,
for tin one-half, for silver one-fourth, for zinc one-half, for tel-
lurium one-half, for copper one-half, for nickel one-half, for
iron one-half, and for cobalt one-third of this. number, &c. ‘e.”

Now, after this sweeping condemnation of. their mode of
proving the law, and of the atomic weights they ig
us compare their numbers with those of Dalton adopted by
Potter, and with those given by Dr Thomson in his Lisiins Ba:
lished History of Chemistry. is
Dalton. § Dulong & Petit. pe

Atomic weight of iron, 25 27.136... 28...
zinc, 29 F224 ois) BM oy
copper, 56 or 28 31.656 32,
silver, 90 54 ' aol 40.4 i
tin, 52 58.8 ello
gold, 60 99.44 1 ODS, 0.
bismuth, 62 LOG. 45. s:ientbee Wee)
lead, 90 103.6, 104

A single glance at these three columns will show whethenlehe:
numbers employed by Mr Potter or by the French philosophers
in verifying the law of equal specific heats, are the nearer to the

Sey
4

on the specific heats. of Metals. . 269

' weights generally received in this country ; and yet, Mr Potter
has the advantage of all the researches made by chemists during
the thirteen years which have elapsed since the French memoir
was published. ‘There is not indeed the slightest ground for
asserting that the numbers in column second are ‘* completely
arbitrary, referring neither to the opinions of chemists nor to
the results of analyses.”

Nor is this all. Mr Potter professes to compare the numbers
of Berzelius with those of Dulong and Petit, ima table given
in page 82; but finding them im the book he has consulted
adapted to the oxygen scale, he multiplies them by seven to
bring them to the hydrogen scale (!!) thus obtaining and setting
down.a list of numbers which no one ever dreamt.of as repre-
senting the atomic weights of these bodies. Though Dalton
adopts the ratio of 7: 1 as expressive of the relation of the atomic
weight of oxygen to that of hydrogen, he ought to have known
that Berzelius, whose numbers he thus multiplies, does not, and
this would have prevented him from falling into such an error.
Let me request his attention to the following extract from Dr °
Thomson’s History of Chemistry, vol. ii. page 297. “ He
(Dalton in the 3d volume of his System, published in 1827,)
still adheres to the ratio 1: 7 as the correct difference between
the weights of the atoms of hydrogen and oxygen. ‘This shows
very clearly that he has not attended to the new facts which
have been brought forward on the subject. No person who has
attended to the experiments made on the specific gravity of these
two gases during the last twelve years, could admit that these
specific gravities are to each other as 1:14. If1:16 be not
the exact ratio, it will surely be admitted on all hands, that it
is infinitely near it."—‘* Dr Ure,” says Mr Potter, * adopts
7.5 as an atom of oxygen.” In which of the ancient authors
does Mr Potter find this?

But in the paragraph already quoted from Mr Potter’s paper,
while he denies that they have proved the law of equal specific
heats, he says the law ‘ holds I find with singular fidelity in
common temperatures, excepting in one very remarkable case,
that of siloer””. Now let us take the atomic weights of Dr-
Thomson, and multiplymg them separately into the specific

2'70 Mr Johnston’s remariss on Mr Potter’s paper

heats obtained ienpossinnty by MM. Dulong and Petit, and by |
Mr Potter, let us see how the constant C comes out in’ each.

Specific heat or S. Atomic Constant or. Cc.

Dulong & Petit. Potter. weights or W. Dulong & Petit. Potter.
Iron, 110 110 28 3.08 3.08 ©
Zine, 0927 098 34 3.158 8.3882"
Copper, .0949 .096 32 3.0368. 3.072 ©
Silver, 0557» .063 55 3.0685 3.465
Tin, 0514 .056 58 2.9812 8.248
Gold, 0298 .046 100 2.9808 4.6
Bismuth, .0288 039 stot 3.1104 2.808

Lead, .0293 .032 104 3.0472 3.328

If the law in question be true, the value of C obtained from
each metal must necessarily approach very nearly to the mean —
of all the values. Now the mean of column fourth is 3. 057,
and all the values of C in that column are so near this mean as
to be completely within the limits of error, the greatest difference
being that of zinc, which is + .101.. The mean value of C in
column fifth, deduced from Mr Potter’s specific heats, is 3.366,
but the differences are more irregular than in column fourth ;
and the greatest is that of gold, which is 1.233 above a third of
the whole. In the one of these columns then, the value of C or
SW is nearly constant, in the other it is very irregular; we are
forced, therefore, to the conclusion, that either the law of equal
capacities does not hold, or Mr Potter's results are inaccurate.

But in column fifth there are three numbers which are con-
spicuously beyond the mean of the other five, and which, there-
fore, in other cases would be rejected in endeavouring to deduce
an accurate mean. ‘These numbers stand opposite to the three
metals silver, gold, and bismuth. ‘The mean of the other five
values is 3.196, which is so near the mean deduced from column
fifth that we may safely rely upon the truth of the law to which
we have so often adverted—though, so far from showing it ‘‘ to
hold with singular fidelity,” we have seen that were Mr Potter’s
results to be depended upon, the law, in the present state of
our knowledge, would be wholly untenable. .

Let us turn now to the specific heat of bismuth, from aiid

3

Dr Muncke’s Remarks on an Account, &c. 271

we have stepped aside so long. We have been obliged to reject
from column fifth the numbers opposite to silver, gold, and bis-
muth ; the presumption, therefore, is, that the specific heats as-
signed to these metals by Mr Potter are too great. But it has al-
ready been shown for other reasons, that those given for gold and
silver are not at all to be depended upon. We are justified in con-
eluding, therefore, that his result for bismuth is also to be rejected.

Opposite to bismuth, in column third, I have mserted two
atomic weights, that of Dr Thomson 72, and that adopted by
MM. Dulong and Petit, which is one-half more, 108; and
while I have multiplied the specific heat of these latter gentle-
men, as they did, by 108, I have given Mr Potter the benefit
of the former number 72, as affording a value of C somewhat
nearer the mean than the other number does. ‘The atom of
silver I have also set down at 55, as this halving of ‘Thomson’s
number was necessary for both determinations.

Whether we adopt the one or the other of these numbers is
entirely a matter of theory; combinations may yet be effected,
such as to render it convenient to make similar alterations in re-
gard to many of the metals. That bismuth may have an atomic
weight of 13.5 or 108, is rendered more probable by some late
experiments of Mr Phillips, by which he has made known se-
veral new compounds * of that metal, in which the ratio of 1:3
prevails among the atoms.

Art. XIV.—4A few Remarks on an Account of the * Meeting
of the Cultivators of Natural Science and Medicine at
Hamburgh in September 1830, by James F. W. Johnston,
M. A. &c. &¢.” as Communicated by the Author to the Edin-
burgh Journal of Science, New Series, No. viii. page 189.
By Dr Munckx, Professor of Natural Philosophy at Heidel-
berg. Communicated in English by the Author.

‘Te account given by Mr Johnston of the Meeting of the Na-

* These are a trisnitrate and a trismuriate. (An. of Phil. December
1830.) Dr Thomson had previously described and analyzed a triscarbonaie,
(First Prin. ii. p. 391,) and Berzelius a tris-sulphate. (Gmelin’s Hand-
buch; i. p. 1009.) All these salts contain one atom acid to three of base.
Were we to consider the atom of bismuth 108, then these would all be
called disalts. Pies

NEW SERIES, VOL, V. NO. Il. OCTOBER 18351. s

.

272 Dr Muncke’s Remarks on an Account of the

turalists and Physicians at Hamburgh, is, amongst all. its inte-
resting matters, blended with so many deformities, that it may —
not only be useful in general to correct them, but it must be
even a satisfaction to Englishmen to be possessed of better infor-
mation. ‘Taking this account on the whole, it is a true and
correct one ; but we are sorry to find it disfigured by palpable
errors, arising from prejudice or misconception, or want of good
information, or, the tria_juncta in uno.

Before I proceed, I must beg to direct the attention of the
reader to Mr Johnston’s translation of naturforscher by culti-
vators; this: is erroneous. Forschen signifies to search, to
seek, to inquire, to pry, to investigate, to examine, and, by
dint of these combined efforts, to improve; the German deno-
inination consequently implies the progress of: science by dili-
gent inquiry, whereas the English adopted by Mr Johnston
implies only or more of a stationary plodding. I hope it may
not be considered superfluous thus to correct this false descrip-
tive denomination of the naturalists, which might otherwise
lead to a false conception of their object. I shall now proceed,
having disposed of the head, to the body of the account.

I do not really mean to be harsh, (to make use of one of Mr
Johnston’s own phrases,) but cannot help remarking, that it
must be considered a breach of hospitality to stigmatize the in-
habitants of a town who have almost unanimously exerted them-
selves towards contributing to the most attentive and cordial
reception of the assembled learned men, in the manner the nar-
rator has done: ‘“‘ a luxurious people, of whom it may be truly
said their god is their belly, (I suppose he meant to say their
belly is their god,) &c. &c.” Are we then to learn from a sub-
ject of the first commercial country in the world, that commer-
cial industry and activity is to be treated with sarcasm and con-
tempt? According to my humble opinion, the mercantile pro-
fession is of full as much importance and as estimable as the
learned ; and what progress could science and the arts have
made without the aid of commerce and navigation, and without
the capital procured by commercial industry? Mr Johnston
might have also learned, by application to proper channels and
authorities, that Hamburgh, without being an university or seat
of learning, may boast of having produced within its walls, men
of European celebrity, as Klopstock, Reimarus, Fabricius,

Meeeting of Naturalists at Hamburgh.. 2738

Busch, Unzer, Gries, and the great composer Bach; and from
its great estimation of learning, and the support given to de-
velopement of talent, is likely to have, from time to time, si-
milar brilliant stars appearing on its commercial horizon. It
may be equally unknown to Mr Johnston, that the readiness of
the Hamburghers in promoting objects of science is of old stand-
ing; and of the general acknowledgment in later periods, Mr
Johnston instances himself, Benzenberg’s Experiments on the
Fall of Bodies, (page 240.) But what Mr Johnston relates
to have been done by the town for the assembly, is in such con-.
tradiction with many of his observations, that his best advocates
could scarcely be able to protect him against the charge of in-
consistency. With regard to the luxury of Hamburgh, Mr
Johnston does wrong to judge by the splendid entertainments
occasionally given to visitors ; although it may be certain, tak-
ing a general view of it, that the Hamburghers, who are good
calculators, have also in this instance not been out of their.
reckoning; for at the elegant and splendid breakfast at the bo-
tanic garden, it has been proved by evidence, that a great many
of the learned men found also other points of attraction besides
science ; and as Mr Johnston called that hour “ one of the hap-
piest he spent in Hamburgh,” we may take it for granted
that he did not belong to the class of those who he describes
(page 231) as having wondered.

Wealth is a natural and necessary condition of a great com-
mercial city ; but it must be acknowledged by the most prejudi--
ced, that the inhabitants of that great emporium of German:
commerce understand to give it a most proper direction by
philanthropic institutions, by developement of talent, and by a
comfortable mode of living and liberal hospitality. In the fa-
mily-circle of respectable merchants, Mr Johnston must, how-.
ever, have found, if he has had the good fortune to frequent
them, that nothing of ostentation and extravagance prevails
there; but certainly a noble hospitality, and the visible desire
to make themselves agreeable to their guests, without the latter
being either merchants or rich; their respectable standing in
the learned world being sufficient qualification to entitle them to
deference and respect. (Having myself with many of my col-:
leagues been in that predicament, I can vouch for the fact.) |
The conversation in such limited domestic circles displayed

9 .
274 Dr Muncke’s Remarks on an Account of the

more interest for scientific objects than I did expect ; and wher

the first modest restraint was broken, then I discovered a much

greater portion of general knowledge amongst the men (and im

several instances even among the ladies,) than might have been’
anticipated from mere mercantile and ordinary education. Not
having been myself at Hamburgh before the last meeting, nor ~

being connected by relationship or other ties to its inmates, I
consequently could not have any claim of preference; and I do
trust I may be deemed an impartial observer on that account.
Let it, however, be considered at the same time, that, if not all
the members of the convention there assembled had the good

luck to be introduced in society, it was owing to the nature and.

character of such a large meeting, of which all the members
present could not possibly be of a distinguished or known repu-
tation, otherwise the number of first-rate literati of Germany

would be enormous, as those congregated at Hamburgh did not.

constitute the tenth part of the whole.

In private societies, as well as generally, it was not difficult
to observe that the better class were not ignorant of the scienti-
fic purport of the meetings of naturalists, which they had even
been long acquainted with from former meetings in other towns.
of Germany, and of course the invitation on the part of the se-
nate and the citizens, could otherwise not have taken place ; and
the many absurd observations Mr Johnston reports from hear-
say (v. 208-210,) are, generally speaking, void of foundation,
and as unbecoming and unfit to be introduced in a report of
that description, as it would be credulous to give credit to them.
It is possible that Mr Johnston or his faithful reporter may
have heard something similar from some fat * or idler; but

~* T hope I may be excused to make use of a French term here, which,

however, in this instance, is the most expressive for the sort of character I
meant to describe, and of which, as cannot be unknown to Mr Johnston,

many are to be found at all times of the day in and about the Alster Pa-
villion, and even out of change-hours at the Boersen-Halle, (not Boursen-

Halle, as Mr Johnston, (probably also from false reports, ) repeatedly calls

that establishment, ) sipping their coffee, and puffing their segars, and ready

to give and receive all sort of scandal, smail talk, and anecdote. Such places”
of resort are most convenient to isolated strangers, but their stationary in- -

mates very bad channels of information, even worse than valéts de place, who
are at least useful to persons who are unacquainted with the locality of a
town, and strangers to thelanguage. An honest valét de place would have told
Mr Johnston that the entrance-money to Mr Bauer’s garden, since its ad-

’ «

Sn

Oy ee ae

Ow eae Soe ee ae

ee ee ae

Meeting of Naturalists at Hamburgh. 275

idlers are weeds of every soil and climate, and no large town is
without them; but their stupid opinions can only mislead the
uninformed. I must, however, be permitted to state my doubts,
founded upon my correct information, that certainly some of the
inferior rank of the inhabitants first complained that the city

was to be burdened with the charge of board and lodgings of the

visitors, but were afterwards not only well satisfied, but glad
when it came to their knowledge that the strangers were come

‘to spend their own money. People of that class are of the same

illiberal spirit and stamp almost in every country, even Great
Britain not excepted; but Mr Johnston and his respected
countrymen would have just cause to complain, if the German
would take from such a narrow-minded class of the nation, the
standard for the national character. This is not the way to
judge of the people, nor is it the means of promoting the closer
connection of respective nations, so desirable and necessary for
the promulgation of the sciences.

The office of president, and more so that of secretary at the
meeting of naturalists, are so laborious and difficult, that it is
much to be feared the association will find it no easy task in
future to obtain proper men ready to occupy these intricate of-
fices, but particularly the latter, should,—as has been the case in
Hamburgh,—many of the congregated members exact to see their
often but too contradictory and unreasonable pretensions at-
tended to; it cannot, therefore, be read without some indigna-
tion “ that a very unfortunate and unsatisfactory choice had
been made in the person of Dr Fricke ;” after which observa-
tion it is ridiculous to see the sweetening of the dose added,
that “ it is not my intention to say any thing harsh of Dr
Fricke ?—” but this is, in point of consistency, on a par with
many other parts of Mr Johnston’s account. Dr Fricke had
been known to most of the members, having attended the pre-
ceding meeting at Heidelberg, and, from having been an active
member himself on that occasion, made himself acquainted
with the routine of the business and the arrangement of the
proceedings; added to which he enjoyed the confidence of his
fellow-inhabitants and the senate of Hamburgh, which, as well
as his indefatigable activity, made him a most fit person for

missions to the same have been appropriated to the poor of Altona and )

Hamburgh.

~

.
276 Dr-Muncke’s Remarks onan Account of the

this arduous and, as it proved, ungrateful office. Had Dr
Lehman (in every respect a most, respectable, unassuming, and
modest man certainly,) been considered a more fit secretary
than Dr Fricke, the latter would not have been chosen ; and
here I must be permitted to place the vote of a whole meeting
against an individual opinion in support of my argument. _

Mr Johnston introduces in his account a great deal of irre-
levant matter of too minor importance to fill many pages, and
his readers would be very badly informed, indeed, were they to
learn from it the manners and customs of the Swedes, the
Danes, the French, and the Germans. . Nothing is easier than
ridiculing certain peculiarities of a nation or nations ; butis there —
one without it? The philosopher, however, the liberal mind-
ed, and the man of good breeding, will respect in others what
he claims for his own. This is a principle grounded not merely
upon a proper moral feeling but on sacred precept. |

Page 233.—Mr J ohnston says, ‘‘ he has heard some stories
when sitting téte-a-téte with a German naturalist ;” and in his
innocent candour adding, ‘‘ that it is chiefly the young men who
are indiscreet enough to tell them,” he commits the very same
indiscretion of a young German naturalist, not téte-a-téte with

a confidential reader, but before the great public—not over a
“glass of punch in the pavillion of the Alster, but in. Dr Brews-
ter’s excellent Journal of Science! But let the same public,
and by the same respectable channel, be informed that the
stories Mr Johnston did introduce were on the continent not
even considered sufficiently well founded to be received in the °
ordinary cursory pamphlets and breakfast journals, as food for
idle readers. . I allude to the story of the king of Denmark
and Professor Pfaff of Kiel, and.the dialogue of a Professor
and the Director of the Police at Vienna.—(Page 235.)

I know very well what gave rise to both these stories, the
first being from the year 1820, and consequently quite out of
date ;—the second happened in the year 1828; but having at
that period been myself in Vienna, and having had the best op-
portunity of obtaining good information, I can positively as-
sert that the story, as reported by Mr Johnston, is quite dis-
figured ; besides, every person of sufficient experience must be
aware that reports of what has passed in the closet between

monarchs and ambassadors ought to be received with caution.
a 3 ; . .

Meeting of Naturalists at Hamburgh. 277

> What regards “ the fear of arbitrary power,” I may be per-

“mitted to observe, that the republic of letters does not know of

any such fear ; and I do not hesitate to say, that learned men
are generally and highly esteemed, as they show themselves
zealous in the performance of their duty—the cultivation of
the extensive field of science. If they deviate from that path,
wandering into politics, opposing established order, and become
factious partizans, then it is no more science which has to com-
plain or to fear arbitrary power. ‘That the meetings were not
before frequented by scientific men from the Austrian domi-
nions, with the exception of Count Sternberg, was merely to be
attributed to the great distance from the former places of meet-
ing, and the prejudice prevailing at their origin, that the ad-
vantageous results were not adequate to the loss of time and ex-
pence. It was not till the king of Saxony had received the as-
sembly of naturalists in his capital, whose curiosities were most
liberally and readily laid open to them, and afterwards at Ber-
lin, when Alexander de Humboldt did not refuse the office of
president, that the meetings were visited by the most distin-
guished learned men, and from that period their established
scientific character may be dated. ‘The association then at-
tracted the attention of the members of the imperial family of
Austria, who are not only distinguished as patrons of the arts

_and sciences, but many of them also by profundity of learning,

and H. I. Majesty’s permission, or rather the invitation to fix
the next meeting at Vienna, might be acknowledged as a sin-
cere estimation of science. Should Mr Johnston, or those who
know that beautiful metropolis only from stories of young men,
happen to join the next meeting, they will then find that it ex-
ceeds in treasures for natural history many other towns, and is not
behind any in point of liberality and hospitality towards strangers. _

It is much to be regretted that Mr Johnston, who is not
void of acuteness of observation, had not been more cautious in
collecting his information, which ought to be the first duty of
a faithful reporter, as it is also his best policy, inas much as he
exposes the credit of the correct part of his account by the hear-
say and deformed information, picked up without discernment,
and introduced without discretion.

I cannot close these remarks without uttering my earnest
wish, that the meetings of: the Naturalists and Physicians’ of

>
278 Mr Johnston’s Reply to Professor Muncke.

Germany may continue to attract the attention, and to enjoy
the benefit of knowledge, of the learned men of other nations,
and that science may cement the union which commercial in-
tercourse had originated, and paved the way for amongst na-
tions. May the language of the Germans also become more

and more familiar to foreigners, to enable them to obtain cor-
rect and unprejudiced information themselves, a as well in a so- |

cial as in a scientific point of view.

HEIDevBere, June 1831.

Art. XV.—Observations on Professor Muncxr’s Remarks
on Mr Jounston’s Account of the Meeting at Hamburgh.
In a Letter to the Evitror from Mr Jonnston.

My Dear Sir,
IT nave to thank you for your kindness in allowing me to per-
use Professor Muncke’s remarks on my Account of the Meeting
of the.German Naturalists at Hamburgh, before they were sent
to press. Permit me to add a very few notes by way of reply.
Professor Muncke is a person of some note, an amiable man,
I believe, and one that I was prepared to esteem. I had not

:

the pleasure of forming his acquaintance at Hamburgh, for a :

mere introduction, followed by the occasional interchange of ‘a
sentence during the several days of meeting, cannot be called
such ; but I shall not soon forget his animated manner when in
his travelling dress he entered the Stadthaus on the morning of
the first day of meeting, and found himself among so many
assembled Naturforscher. I at once set him down as an en-
thusiastic man, and in such men I have generally found some:
thing worthy of esteem and admiration.

It is therefore gratifying to me to learn from Professor
Muncke that my account, ‘* on the whole, is a true and correct

one,” even when he takes up his pen deliberately to point out —

my errors. I have gone wrong, he says, from one or all of three
causes, from prejudice, from misconception, or from want of
good information. From wilful error or misrepresentation he
acquits me therefore, and so far he does me only justice.
Whoever has honoured me by the perusal of my account of
the meeting at Hamburgh, will bear me out in saying, that it

\ |
any

4

Mr Johnston’s Reply to Professor Muncke. 279

is not written in a critical or censorious spirit. I went to that
meeting with the hope of being gratified,—I was gratified,—and
I have expressed my gratification. And yet, Sir, were I to sit
down to find fault and to pick out. blemishes in my own paper,
I could produce a much more formidable list than Dr Muncke
has done ; for where so many topics are touched upon, while
all is true and correct, on the whole, it is hardly possible to

avoid some slight mistakes. Let us see how many of these Dr

Muncke has detected. __

First, then, I have translated Naturforscher erroneously. It
is a ‘* false descriptive denomination,” it seems, to call German
philosophers Cultivators of Science. Cultivators, says the
Doctor, and they know English well at Heidelberg, are mere
stationary plodders,—and your Germans are no plodders! Dr
Muncke is a Professor of Physics, and it does not become me

_ to argue with him on the doctrines of mechanics ; but it would

be interesting to learn, in what part of his Compendium der
Naturlehre he treats of stationary plodding. It must be inti-

_ mately connected, I should think, with that interesting species of

progression known by the name of the Stand-still motion.*
After this serious exordium, Sir, it was a great relief to find
in the second paragraph, that the Doctor did not ‘* really mean
to be harsh with me,” and I am quite as grateful as need be
for his forbearance. Oue of the main objects of his communica-
tion is to defend the Hamburghers from my assertion that they
are a luxurious people. But how will his wrath be excited
and his forbearance regretted by him, when I add further, that of
all the cities I have visited, Hamburgh is the one in whichthe tone
of morality is the lowest,—in which the means of licentiousness
are the most abundant, most accessible, and most luxuriously
and publicly provided,—and in which the practice of immora-
lity is least regarded. And does the learned Professor really
think he can persuade his readers, that the Hamburghers either
know or care any thing about science. It cannot be that in a
city which nightly confines within its walls 120,000 souls, there
should not be some scattered gleams of genius at times bursting

* “ How many kinds of motion are there,” said a Glaswegian professor
of physics to one of his very bright pupils. ‘‘ Three, Sir,” was the reply.
“ Three ! name them.”—‘* The Retrograde, the Progressive, and the
Stand-still motion.”

280 Mr Johnston’s Reply to Professor Muncke.

forth, or that science even there should not have its rare yet faith-
ful votary,—and T have not been backward in giving her credit
for now possessing such men,—yet, even with these exceptions,
the people are not the less a mercantile people,—heedless of sci-
ence,—and in whom, however ludicrous total ignorance of scien-
tific matters may occasionally have appeared, yet ignorance is in
a great measure excusable.

The Doctor is a matter of fact man, and cannot tolerate ue
many irrelevant and absurd observations I have introduced ;
especially about the Hamburghers and their fear of being burden-
ed by the arrival of so many strangers; and to set me right, he
gives the result of his correct, which is in sum and substance just
the same as my imcorrect statement. I have introduced a few
sentences of colloquy which the learned Professor did not hear,
and therefore, forsooth, they are incorrect. One must not, it
seems, enliven a dry account of a meeting of naturalists with a
few on dits, but out steps one of your German professors, —ex-
claims against their absurdity, and wonders you should give
credit to them. Poor calumniated Hamburghers! I shall never
be able to face you more.

Now, regarding our opportunities for information, let me com-
pare notes with the Doctor. By his own confession he never
was in Hamburgh before, and he has no connections through
whom he could have obtained information regarding the city or
what was going on. He talks, indeed, of a valet de place hav-
ing been very useful in telling him about Bauer’s garden and
various other matters; but that is what the stranger who visits
Hamburgh for the first time cannot do without. He arrived, I
believe, on the first day of the meeting, and he spent about eight
days in all, during which time he was occupied, as all were, with
the proper business of the assemblage. I had visited Hamburgh:
previously ; I spent nearly a month in it at the time of the
meeting, and I have visited it since. My opportunities of ac-
quiring information, therefore, both concerning the place itself,
and what passed about the time of the meeting, I am entitled to
say were superior to those of the Professor.—Alas ! he will ex-
claim, that you should have made so little use of them !

But the Doctor cannot read without indignation “‘ thata very
unfortunate and unsatisfactory choice ‘was made in the person

;
j
K
:

Mr Johnston’s Reply to Professor Muncke. 281

of Dr Fricke,” who had been named secretary to the meeting.
I mixed much among all classes of the Naturforscher while -at

- Hamburgh, and made more new acquaintances perhaps than any

other stranger at the mecting; and my persuasion is, that the
choice gave general dissatisfaction, and was therefore unfortunate.
He must have been particularly kind to Professor Muncke to
have gained so far upon his good graces. And if the selection
was so generally acceptable, what may Dr Muncke mean when
he says, (p. 275,) “* the association will find it no easy task in
future to obtain proper men ready to occupy the intricate of-
fice of secretary, should,—as has been the case in Hamburgh,
—many of the congregated members exact to see their often
but too contradictory and unreasonable pretensions attended to.”

Of course it cannot mean any thing inconsistent with what he

_ has elsewhere said.

I am particularly grateful for the correction in the spelling
of the word Bérsen. On referring to my note book, I find it is
not an error of the press but a defect of knowledge in myself.

- It shows how diffusive is the Doctor’s philanthropy when he

has been at the trouble to write all the i from Heidelberg to
inform me of my error.

There is little else to which I need advert. Dr Muncke is
offended at the two anecdotes I have inserted in illustration of
the arbitrary spirit of the German governments. He says they
were not considered sufficiently well founded to be introduced
into the breakfast journals of Germany. And yet he tells us
that the two circumstances actually took place, the one in 1820,
the other in 1828, when he was himself in Vienna! Does

he really wish us to believe that every thing well founded

finds its way either into the breakfast or dinner journals in
Germany. The very exclusion of such anecdotes, which
spread from north to south nevertheless, is just a proof of
what I stated, that the governments are suspicious and. arbi-
trary. Did Professor Muncke of Heidelberg, in the course of
his travels, ever hear of such a thing as a censorship of the
press ? We have not now to learn, however plausibly he may talk
the matter over to us, that in his fatherland the republic of let.

_ ters is a mere name. And then as to the foundation of these

two anecdotes, the one I had, among other persons, from a di-

a
282 Round Sterns.

plomatist, and from a Privy Councillor of his Danish Majesty ; 5

for the other, Dr Muncke is sufficient authority. They may
not, they cannot, be given as they occurred; but the spirit I’

think is preserved, and that alone is important. le

The Doctor waxes witty in page 276 at the expence of my
discretion in telling these on dits. 'This is all fair and allow-
able in men so much older and more experienced than our-
selves. But I would humbly suggest to him as a metaphysi-
cian, if it is not the knowledge of evil consequences to follow
which constitutes the indiscretion in such cases,—and that, as

we fear none in this free country, there can be no indiscretion

even in publishing what men dare hardly whisper in Germany:

In conclusion, Sir, I have to regret that Professor Muncke,
who, I am willing to believe, writes more conclusively on Natu-
ral Philosophy, should have said so much and so sweepingly of
my incorrectness, and yet should have adduced so few, and these
so trifling, proofs of his assertion. Had he made any grave
charge, I should have met it in a corresponding style. Such
as he has made, he will excuse me for treating lightly. I hope
his next communication will be such as to do honour to your
Journal, to himself, and to the university he adorns.—I am,
Dear Sir, your’s very sincerely.
James F. W. Jonnston. ©
Portose Lio, 23d August 1831.

Art. XVI.—Round Sterns. By a CoxresPonvenr.

Iw some former numbers of this Journal, in the Edinburgh
Philosophical Journal, and also in the Edinburgh Encyclopedia,
the important question of round sterns has with much generality
been discussed ; and it is therefore with no ordinary pleasure
that we find a splendid prize has been offered by the French
Minister of Marine, for determining among all the forms that can
be presented that particular one, which shall unite in the highest
degree all the requisite conditions that the seaman, the ber
architect, and the geometrician may require.

Our readers are aware that a vigorous contest was for a long

time kept up respecting the principle of the round sterns; but

Round Sterns. 283 ~

: time, which softens differences, and with a gentle hand moulds

a

even prejudice itself into the form of truth, has in this case ob-

tained another victory ; and a figure which our gallant seamen

had connected with the glorious recollections of Trafalgar and the
Nile, is now,—with wisdom which cannot be too highly prais-
ed,—nearly if not altogether abandoned. The square stern, with
all its massy and cumbrous forms, has indeed given way to an-
other, more in unison with the great march of improvement now
going on.

But while the principle of what is commonly called the
round stern has with few exceptions been admitted in all its ful-
ness, its best possible form has not been determined; and it
would seem as if fancy, rather than the sound discretion which
geometry imparts, had presided over the designs hitherto submit-
ted to the world.

Among the infinite variety of forms which may be ane
“‘ round,” there must be one which shall unite in a higher degree
than any other, all the best conditions of strength, convenience
and defence ;—which shall secure to the brave sailor the great-
est degree of comfort, add a new arm to his power in the day of
battle, and secure to that portion of the frame-work of the ves-
sel, the same admirable strength as distinguishes its other parts.
It is this choice of forms, which the French minister of ma-
rine now invites the naval architect, the sailor, and the man of
science to contemplate ; and we hail the call as a revival of the
days when the great men of the Academy of Sciences, clad in the
armour of the transcendental geometry, descended from the lofty
elevation of the system of the world, to contend for the condi-
tions of the metacentre, the great principles of stowage, the pro-
blems of masting, of pitching and of rolling, and all the other
complicated but interesting inquiries, which the general question
of ship-building involves.

Our Journal, read alike by geometricians, the naval architects
and the sailor, can hardly be better employed than in recording
the conditions which the French minister has proposed for this
great problem.

‘* To furnish the best plans for the circular sterns for line
of battle ships and frigates; with all the exterior and_ interior
fittings, the manner of disposing the timbering so as to combine
the necessary conditions for defence, with strength, lightness, a

8
>

LB 4 Round: Sterns.

dispersion of the weight in proper proportion to the displace-»
ment of each part, the efficiency of the rudder, the convenience

of the water-closets, and the. eae suitableness of the accom. .
modations.

‘*‘ This manner of fitting the stern must possess facilities for »
enabling the commandant to be aware of whatever manucevres
may be in progress, without being obliged to appear on deck.

“The style of ornament which it would be proper to adopt, .
as well for the forward as for the after part of these new con-
structions, is also to be described. The competitors are to remem-
ber that nothing of importance is to be at all sacrificed to these
decorations.

‘‘ The side of the ship at the stern must have the same thick-
ness as at the corresponding places in other parts of the ship.
The ports must be so disposed, that it may be easy, on each:
deck, to bring guns to bear right aft and on the angles of the
quarters, to command those points which the other guns cannot:
be brought to bear upon. |

‘‘ The rudder may be fitted either without board, or within.
with a circular head, but reasons must be given for whatever
plan may be proposed. Reasons also are to be stated for the
station which may be proposed for the water-closets, whether:
they are fitted interiorly, or in an exterior gallery.

‘¢ The officers of the different branches of the naval service: —
are called upon to send their proposals to the minister before the:
[st of July 1832. Other persons wishing to become ri ks
tors, are eligible to do so. *

‘¢ The memoir in which each competitor explains his propo-)
sals, must be accompanied with all the calculations and drawings:
which may be necessary to render his plan perfectly complete.
and intelligible in all its details.

‘“¢ Each proposal must have a motto affixed to it, of which ‘a
copy is to be enclosed in a sealed letter, containing also the name
and place of residence of the proposer.

‘* A medal of the value of 2000 francs will be given to the.
author of the best memoir presented to the minister of marine
before the stated period.” |

* The field is therefore open to our countrymen.—Ep,

DrHibbert’s Observations on Vitrified Forts: 285.

Arr. XVII.—Observations on the Theories which have been
proposed to: explain the Vitrified Forts of Scotland. By
S. Hiszert, M.D. F.R.S. Ed. &e. &e. (From the Ar-
cheologia Scotica, vol. iv. )

‘Tue members of this Society are no doubt familiar with what
is meant by a Vitrified Fort. By this term is implied an area
of ground, often of a round or elliptical form, and evidently
selected for some natural defence possessed by it, which is far-
ther protected by one or more inclosing ramparts, formed by
stones ; these stones showing, to a greater or less extent, marks
of vitrification, by which they are cemented together.

_ None of these vitrified forts exhibit, as from many writers
we should be erroneously led to suppose, any regular masonry
in their structure. Unhewn fragments of stones, and water-.
worn boulders, sometimes mingled with smaller gravel, appear
in a quantity almost exceeding belief, following the contour of
the summit of a mountain, or, as in the instance of a fort which
is situated in the Kyles of Bute, following the contour of a
small holm or islet, elevated a few yards only above the level
of the sea; and in cases where, owing to the more exposed
nature of the ground, a stronger defence is demanded, a dou-
ble or even treble rampart of the same rude materials is added.
The vitrification which characterizes these forts is, in some few
of them, displayed to an extent that is perfectly astonishing ;
while in other instances it is with difficulty to be detected. In.
short, no two forts in their degree of vitrification are in any
respect conformable to each other ; and it 1s of importance to
add, that throughout Scotland numerous forts appear, only
differing from \ aaa which form the present object of inquiry
in the absence of all marks of vitrification whatever.

These forts first met with scientific attention about half a
century ago, when various theories were proposed to account.
for the origin of their vitrification. _ At these I shall glance in
succession.

Ist, The notion that the vitrification observable in these forts
was the result of volcanic agency.

During the last century it was a very prevalent notion, that .

286 Dr Hibbert’s Observations on Vitrified Forts.

the vitrification of these forts had a volcanic origin ; and hence

that volcanoes at some remote period had been very common

in Scotland. This opinion was embraced by Mr Pennant, the
eminent naturalist, who-was Jed to it from an examination of
the Hill of Craig Pheedrick. A similar view was taken up by
Thomas West, Esq. the author of a paper published in the.
Transactions of the Royal Society of London for the year 1777;
and, four years afterwards, by the Hon. Daines Barrington.
The circumstances which led to this opinion have not been
ill explained by Dr James Anderson of Monkshill, Aberdeen-
shire, in-a letter dated the 27th November 1777, and read to
the Antiquarian Society of London “ It must be owned,”
says this author, ‘ that the natural appearance of the places
where these vitrified masses are usually found, is well caleula-
ted to favour the opinion that they have been produced by
volcanoes. The vitrifiable matter is usually first discovered
by travellers around the bottom and on the sides of steep hills,
frequently of a conical shape, terminating in a narrow apex,

exactly resembling the hills that have been formed by the erup- ~

tions of volcanoes. It is therefore very natural to think that
these may have been produced the same way. Let us, for in-
stance, suppose that a traveller strongly impressed with this
idea, should resolve to examine the top of the mountain more
nearly, and for this purpose ascend to the summit :-——-would
not his former conjecture be much confirmed when, at the top,
he should find himself in a circular hullow, surrounded on all
sides by matter rising gradually higher to the very edge of the
precipice, which is there entirely environed with vitrified mat-

ter of the same kind with that which he had found at the bot-

tom ? Could such a man be called unreasonably credulous if

he should be induced by so many concurring circumstances to’

believe that this had been a real voleano? But would he not
be reckoned sceptical in the extreme if he should entertain the

smallest doubt of the truth of this opinion, upon seeing the

very opening itself in the centre of the hollow, through which
the boiling lava had been ejected ?” :
Such is the liberal excuse assigned by Dr Anderson for the

volcanic hypothesis, which is the more generous, as he came’

prepared to advocate a very different theory. Indeed, from
A :

ee ns

ay ee

Dr Hibbert’s Observations on Vitrified Forts. 287

my own experience, I do not hesitate to say, that some few of
these forts are not ill calculated to favour the deception. In
a hasty survey which I took of the hill of Finhaven (the first
vitrified fort I examined) I saw, like Mr Pennant, an apparent
crater-formed cavity, filled with fused materials, occurring in
such an abundance as to render unsatisfactory any explanation.
which has been hitherto given of the artificial mode in which
vitrification to this immense extent must have been produced.
But my illusion was short-lived ;—in the examination of a se-

cond example it was instantly dispelled.

Qdly, The theory, that vitrification was artificially isidecd
as a cement for the consolidation of ramparts of loose stones.

In the year 1777, the validity of the volcanic theory was
first opposed in a pamphlet published by Mr John Williams,
mineral surveyor and engineer for the forfeited estates of Scot-
land.

This author, in advocating the artificial origin of vitrified
forts, first assured himself, on the authority of a late eminent
chemist, that many varieties of the rocks of Scotland were with
little difficulty fusible. Dr Black’s letter to him on this sub-
ject may perhaps be worth quoting: ‘* There are in most parts
of Scotland different kinds of stones which can, without much
difficulty, be melted or softened by fire, to such a degree as to
make them cohere together. Such is the greystone, called
whinstone; which for some time past has been carried to Lon-
don to pave the streets. Such also is the granite or moorstone,
which is applied to the same use, and pieces of which are plainly
visible in some specimens of those vitrified walls which I receiv-
ed from my friends. There are also many limestones, which, in
consequence of their containing certain proportions of sand and
clay, are very fusible ; and there is nodoubt that sandstone and
puddingstone, when they happen to contain certain properties
of iron mixed with the sand and gravel of which they are‘com-
posed, must have the same quality. A puddingstone composed
of pieces of granite must necessarily: have it. -There is abuni-
dance of one or other of these kinds of stone in many parts of
Scotland ; and, as the whole country was anciently a forest,
and the greater part of it overgrown with wood, it is easy to

NEW SERIES, VOL. V. NO, Il. OCTOBER 1831. T

288 Dr Hibbert’s Observations on Vitrified Forts.

understand how those who erected these works got the mate-
rials necessary for their purpose.”

After Mr Williams had thus got over the difficulty of arti-
ficial fusion, he promulgated his view, which, as he states with
much naiveté in his preface addressed to Lord Kames, appear-
ed so incredible that no booksellers of London would hazard
the publication of it. He supposed that the ancient inhabi-
tants of Scotland derived their earliest notion of vitrification,
“ first, from melting bog ore, in the process of which they
learned how it would, if increased, vitrify stones and earth ;
secondly, from observations made while roasting oxen. It is
evident,” adds this choice antiquary, “ from the records of the
earliest antiquity, that it was the practice of almost all nations
to offer burnt sacrifices. And it was customary, on solemn
occasions, to burn a hegetized animal whole, which would re-
quire a very strong fire.”"—“ After they [the ancient inhabi-
tants of Scotland] became acquainted with this power of heat,
I suppose some genius among them to have employed it for
forming vitrified walls. The manner, however, in which he
employed it is still problematical. I have tried the subject se-
veral ways in my own mind, but find difficulty in all the me-
thods I have yet imagined. I shall, however, mention that which
satisfies myself the best, and which appears most practicable.
I imagine they raised two mounds of earth parallel, and in the
direction of their intended wall; and that they filled the ground
formed by these parallel mounds with fuel, above which they
laid the materials to be vitrified. There is no doubt but a
strong fire would fuse these stones, especially if they were of
the plum-pudding kind, and not too large; and the frame of
earth would prevent them, when in fusion, from exceeding any
assigned breadth. I suppose they added layers of fresh fuel
and materials alternately, and raised the mounds of earth till

the whole was brought to the intended height. I am confident,
from the appearance of the ruins, that the materials of them
were run down by the fire in some such method as this. For
in all the sections which I have seen, whether of the larger or
of the smaller fragments of these ruins, I never observed the
least appearance of a stone being laid in any particular way.

Dr Hibbert’s Observations on Vitrified Forts. 289

Nor could I in any of them discover a stone, large or small,
not affected by the fire, and in some measure vitrified.”

“In connection with this theory, Mr Williams defines the
walls of a vitrified fort, when complete, after the following
manner :—‘ The walls are vitrified or run and compacted to-
gether by the force of fire, and that so: thoroughly, that most

of the stones are melted down, and any part of them not quite

run to glass is entirely enveloped in the vitreous matter ; some-
times also they appear like vast masses of coarse glass or slag.”

But we shall now examine, with some degree of attention,
the validity of this theory, particularly as it has recently met
with a defence from a writer of no small eminence, who pos-
sesses a store of antiquarian and mineralogical knowledge, which
eminently qualifies him to enter the lists in the determination
of this question. I allude to a memoir published in the T’ran-
sactions of the Geological Society of London, by Dr Maccul-
loch, and to his views on the subject which are contained ‘in
his description of the Highlands and Western Isles of Seot-
land.

The drift of the theory in question is,—that with the “ae.
sign of strengthening the walls of a fort, the stones have been
cemented by a regular process of vitrification.

In support of this view Mr Williams has stated, that in none

‘of the vitrified forts which he examined could he discover a

stone, large or small, unaffected by the fire, or which was not
in some measure vitrified. This assertion, if correct, would
certainly go a great way to urge conviction, that the vitrifica-
tion of these forts was not an accidental or adventitious, but a _
designed process. Never was there, however, a more unfound-

‘ed statement. At Dun Evan, where there is an extensive for-
tified site, the vitrification so far from’ having acted upon every

stone, is only to be detected in a space the dimensions of which
do not exceed two or three yards. I can also avow, without
dread of contradiction, that in numerous other sites the vitri-
fication is only to be found in small patches, or that extensive
portions of the ramparts which have composed their defence
do not show in the slightest degree the effects of fire.’ Nay,
even in the forts which display the greatest extent of vitrifica-
tion, considerable intervals may be readily traced where no

=

+

290 Dr Hibbert’s Observations on Vitrified Forts.

fusion of the stony materials has ever taken place. These cir-
cumstances, then, are fatal to the notion that vitrification was
the effect of design ; they rather show that it was merely in-
cidental to some other view, which the authors of it must have
contemplated.

This theory is again as ill supported in its details. Mr Wil-
liams has supposed that the builders of these forts raised two
mounds parallel to, or in the direction of their intended wall,
and that they filled the ground formed by these parallel mounds
with fuel, above which they laid the materials intended to be
vitrified. Now this supposition is faulty, inasmuch as it proceeds
upon an incorrect view which has been taken of the actual con-
struction of these forts. A wall formed in such a manner
would present to view a pile of stony materials, with sides which
would be vertical, or at Jeast nearly so; and it would inclose
the summit of a hill after the manner of a modern park wall.
But this is not the character of a vitrified fort. The structure
of the least dilapidated example is much more rude, being rather
after the model of a filled up or extinct volcanic crater. Upon
the summit of an insulated hill, an incredible accumulation of
loose stones has been made to rise to the greatest height around
its circumference, and to gradually thin off towards the centre
of the enclosed site. An ori-
ginal form of this kind could
not then have been derived ©
from any parallel mounds.
This is evident from the an-_ 4
nexed imaginary section.

_ These are the chief reasons which induce me to regard the

theory of Williams as perfectly utenable. : 4

3dly, The theory of Dr Anderson, that vitrification was sibs
moted by the employment of a peculiar vitrescible ore.

The theory of Williams, during the same year in which a
was divulged, met with some qualified support from Dr An~
derson, in the dissertation by him to which I have already al-

luded. He observed of the walls of Knockfarril, that ‘they con-
sisted of stones piled rudely upon one another, and firmly ce.
mented together by a matter that had been vitrified by means
of fire, which formed a kind m artificial rock that resisted.

Dr Hibbert’s Observations on Vitrified Forts. 291 ~

_ the vicissitudes of the weather better perhaps than any other
- artificial cement that had ever yet been discovered.”

Thus, in coinciding with Williams, that vitrification was in-
_ -tended as a cement to strengthen the walls of forts, he only
_- differed from him in the more correct view which he took of
4 the real structure of these defences, or in the theoretical use
_ which he made of an extraneous vitrescible matter. He pro-
_ perly remarked of the vitrified fort of Knockfarril, that its
__ wall was continued quite round the area, being adapted to the

form of the hill, so as to stand on the brink of a precipice, all
: round, with the exception of the places of entrance. Such
f being its construction, he next supposed that vitrification was
_ effected by the aboriginal Britons after the following manner:
** Through all the northern parts of Scotland, a particular
kind of earthy iron ore of a very vitrescible nature. much
abounds. This ore might have been accidentally mixed with
some stones at a place where a great fire was kindled, and
being fused by the heat, would cement the stones into one solid
_ mass, and give the first hint of the uses to which it might be
4 applied. A few experiments would satisfy them of the possi-
__ bility of executing at large what had been accidentally discover-
_ ed in miniature. This knowledge being thus attained, no-
_ thing seems to be more simple and natural than its application
_ to the formation of the walls of their fortified places. Having
made choice of a proper place for their fort, they would raise
a wall all around the area, building the outside of it as firm
as they could of dry stones piled one above another, the inter-
stices between them being filled full of this vitrescible iron ore ; .
and the whole supported by a banking of loose stones ‘piled
carelessly behind it. When the wall was thus far completed,
with its facing all round reared to the height they wished for,
nothing more was necessary to give it the entire finishing, but
to kindle a fire all round it sufficiently intense to melt the vi-
trescible ore, and thus to cement the whole into one coherent
mass, as far as the influence of that heat extended. As the
country then abounded with wood, this purpose. would be
readily effected by building a stack of wood round the whole
outside of the wall, and then setting it on fire. It was pro-~
bably with a view to enable them to build this stack of wood

. ;
292 Dr Hibbert’s Observations on Vitrofied Forts.

with the greater ease, and to suffer the fire to act more forci-
bly and equally upon the different parts of the wall as it gra-
dually consumed, that they were induced to incline the walls
so far from a perpendicular position. In an after period, when
the woods had gradually been destroyed, and before it was
well known how to manufacture peat for fuel, it would be such
a difficult matter to procure fuel in abundance, that build-
ings of this kind would come to be disused, and the art in a
short period, among a people ignorant of siti be entirely
forgotten.” : vet

Such is the explanation of the process of vitrifying, as given
by Dr Anderson, with the discovery of which he is so delighted
that he patriotically adds, “* I am disposed to believe that this
has been entirely a British invention, and think it probable that
the art was never carried out of this country.” He then laboured
to prove that so admirable an art was unknown to the Danes,
who endeavoured to vitrify some walls round the peninsulated
rock of Broughhead ; but having blundered by getting ae
of some wrong vitrescible ore, the experiment failed. |

On this view of Dr Anderson nothing more may be remarked,
than that it is in contradiction with the real facts concerned in’
this vitrification.. All later observers have agreed, that the
fusible matter does not consist of any peculiar vitrescible iron
ore found in Scotland, but that it is derived for the most part
from the alcaline ingredients of well-known rocks of granite,
gneiss, mica-slate, clay-slate, hornblende schist, sandstone, &c.
&c.; these rocks: being more or less fusible in Dre mt to
the felspar which they contain.

4thly, The theory of Lord Woodhouselee, that ‘Sie has not.
been employed in the construction, but towards the eat |
such forts as display the marks of vitrification.

In a paper published in the year 1787, in the 7’ ransactions
of the Royal Society of Edinburgh, Lord Wocdhouselee suc-
cessfully exposed the weakness of the theory first proposed by
Williams, and supported to a certain extent iby Anderson ant
other writers. |

His Lordship proceeded upon the correct ground, that she
vitrification of forts was a very partial occurrence ; that three

fortified summits which he examined were crowned with stone
3

a ar, ee

‘

Dr Hibbert’s Observations on Vitrified Forts. 293

structures, showing no appearance whatever of the effects of
fire ; and that the number of such forts as displayed marks of
vitrification would be found inconsiderable, when compared with
those which have not been at all affected by heat.

The same able writer also questions, with much propriety,
the capability of constructing an efficient fortress of vitrified
materials. He doubts whether it would be at all possible, even
at the present day, by the utmost combination of labour and
skill, to surround a large space of ground with a double ram-
part of stones compacted by fire, of such height and solidity as
to serve any purpose of security or defence against a besieging
enemy ; and concludes that any structure of this kind must
have been irregular, low, fragile, easily scaled, and quite
insecure. | [7208

The hypothesis of Williams having been thus shown to be
perfectly unsatisfactory, Lord Woodhouselee next proposed
a theory of his own. It was suggested by the observations
which he made, that vitrified mounds do not appear to have
been ever much higher than they are at present ; that even ia

_. those sites where the wall was the least elevated, the fragments

which have fallen down from it were very inconsiderable. His
Lordship was therefore led to suppose, that the ramparts which
now remain convey to us a full notion of the original construe-
tion of these forts,-which was not of stones only, but which
depended for their chief defence upon the wood which was
employed in their fabric. He supposed that the building was
begun by raising a double row of palisades, or strong stakes,
in the form of the intended structure, in the same way as in
that ancient mode of building, described by Palladio, under

the name of Riempiuta or a Cassa, coffer-work ;—that these

stakes were probably warped across by boughs of trees laid
very closely together, so as to form two fences, running parallel
to each other at the distance of some feet, and so close as to
confine all the materials, of whatever size they might be, that |
were thrown in between them ;—and that into this intermediate
space were cast boughs and trunks of trees, earth, and stones
of all-sizes, large or small, as fast as they could be quarried or
collected ; very little care being necessary in the disposition of

>

294 Dr Hibbert’s Observations on Vitrified Forts.

these materials, as the outward fence would keep the mound
in form.

The learned writer having thus constructed a fortress of sie,
own, or rather one that was borrowed from an Italian archi-—
tect, proceeded to develope his newer theory of vitrification,
which was, that in a structure composed of combustible and _
fusible materials, the effects of fire would be accidental ; that
they would be induced, not during the construction, but dur-
ing the demolition, of a fort.

‘‘The most formidable engine of sattack,” rewnitehd his
Lordship, ‘ against ‘a structure of this kind, would be fire;
and this, no doubt, would be always attempted, and often sues
cessfully employed, by a besieging enemy ;—and if the~be-
slegers prevailed in gaining an approach to the ramparts, and,
surrounding the external wall, set fire to it in several places, the
conflagration must speedily have become general, and the effect
is easy to be conceived. If there happened to be any wind at
the time to increase the intensity of the heat, the stony parts
would not fail to come into fusion, and, as the wood burnt
away, sinking by their own weight into a solid mass, there
would remain a wreck of vitrified matter tracking the spot
where the ancient rampart had stood, irregular, and of unequal
height, from the fortuitous and unequal distribution of the
stony materials of which it had been composed.”

This theory, in its application to a country so well wooded
in times of yore as Scotland, merits some notice, though it
must be confessed that it is much easier to frame a notion of
this kind, which is little more than the offspring of a fertile
imagination, than to completely refute it. The chief objection —
which I have to this hypothesis is, that in many forts which
I have examined there is no indication whatever that their
structure was at any time different to what they display at the
present day ; and that the encompassing stone mounds appear to’
have afforded a sufficient defence to a savage people, without
the addition of ramparts of wood. His Lordship must have
anticipated the latter objection, by citing the exceptions to his
theory, which he explains after the following manner :—* In
those parts,” he observes, “‘ where stones would be easily quar-
ried of such size and form as to rear a rampart by themselves

Dr Hibbert’s Observations on Vitrified Forts. 295

of sufficient strength and solidity, there was no occasion to em-
ploy wood or turf in its construction, and it was therefore
proof against all assault of fire. Such are the ramparts which
appear on the hill of Dun Jardel, Dun Evan, &e. But on
Craig Pheedrick and other hills, where, from the nature of the
rock, the stones would be-procured only in irregular and gene-
rally small fragments, it was necessary to employ some such
‘mode of construction described.”

_ . These are the chief reasons which have induced Lord Wood-
houselee to form an opinion differing from that of Mr Williams,
and of such as believed these structures to be the proofs of an
ancient mode of building, in which fire was employed for the
: purpose of a cement before our ancestors knew the use of lime.
He is rather disposed to conclude that the appearances of vi-
trification, which a few of these fortified sites evince, are the
accidental effects of fire upon a structure composed of combus-
tible and fusible materials, and by no means the consequence
of an operation intended to produce that effect.

My own opinion of his Lordship’s demolishing theory is
scarcely a decided one. I cannot think it likely that in all
cases structures of wood were called in aid to give additional
security to mounds of stone. The probability, however, of
rude wood-work being occasionally employed for this purpose.
must be admitted ; and perhaps it may be illustrated in forts
of very small dimensions. But that vitrification was induced
by their being set on fire by a besieging enemy, is a distinct
proposition, which in most instances will, I am persuaded,
meet with no countenance whatever.

5thly, The opinion that the vitriyication of these forts was
the result of beacon-fires.

A fifth and last opinion, said to be the most plausible one
that has yet been broached, is, that the vitrification of these
forts was the result of beacon-fires. This theory has met with
maliy supporters, particularly among the contributors to Sir
John Sinclair’s Statistical Account of Scotland. But the most
able advocate of this opinion is Sir George Mackenzie of Coul,
Bart in an article on vitrified forts, written by him for Dr
Brewster’s Encyclopedia, and in his published’ letter addres-
sed to Sir Walter Scott, on the vitrified fort of Knockfarril.

296 Dr Hibbert’s Observations on Vitrified Forts.

The chief arguments for this opinion are, that the marks of
fire are indicative of an accidental rather than of an intentional —
effect, and that vitrified forts are generally situated on lofty
insulated bills, in such a chain or mutual connection as to allow
of telegraphic communications to. be conveyed from one station
to another at a considerable distance. ‘
But even this theory is not without its difficulties. In a
dissertation lately printed in a volume of the T'ransactions of
the Royal Society of Edinburgh, by James Smith, Esq. of Jor-
dan Hill, a fort in the Kyles of Bute is described, which oc-
cupies the site of an islet or holm not more than twelve or
fifteen feet above high water mark. Arguing therefore from
this circumstance, as well as from the regularity of its vitrifi-
cation, the writer comes to the conclusion, that the effect of
signal-fires will not account for the fort in question, because
the situation, in a flat surrounded on every side by hills of
considerable elevation, does not appear at all calculated for
such a purpose ; and because, in the next place, the regularity
of its form seems still more inconsistent with the effects of an
accidental cause.
Many who have supposed that the vitrification of these an-
cient remains was the result of beacon-fires have offered con-
jectures on their date. In a communication read to the Phi-
losophical Society of Manchester, by Dr Milligan, the author
is of opinion that they were in use among the earliest mhabi-
tants of Caledonia; and he supposes that, as the invasion of
Agricola was attended by a fleet on the coast of Scotland, the
fires seen in the interior of the country, which Tacitus describes
as the flames of dwellings kindled by the inhabitants, might
have been signal-fires communicating from hill to hill, as, for
instance, from Stonehaven to Bute, where a line of vitrified
forts may be traced ; and that this telegraphic communication
was the prelude of the battle of the Grampians. Various other
writers, however, assign to these forts a much later date, par-
ticularly the contributors to Sir John Sinclair’s Statistical Re-
ports. 'They conceive that they were in chief requisition as
beacons during the descents of the Northmen, which lasted
several centuries.
. This last opinion many, if not most, of the vitrified sites

Dr Hibbert’s Observations on Vitrified Forts: 297

which have been examined, tend greatly to support. The
coasts of Scotland began to be annoyed by the predatory vi-
sits of the Vikingr about the end of the eighth century ; but it
was not probably until the Scots had obtained a complete as-
cendency over the Picts, by which both were united under one
government, that systems of beacons were formed to provide
against the sudden descents of the Scandinavians, who invaded
them from the Danish or Norwegian shores, or from countries
which they subsequently colonized, namely, from Shetland,

Orkney, Caithness, Sutherland, the Hebrides, Ireland, or the
Isle of Man, The Murray Frith, as we learn from ancient
Sagas, was one of the most convenient landing-places for the
Northmen ; and hence we must look to this locality for the
greatest proportion of vitrified sites. The number of such as
have been traced within sight of each other, in a direction east
to west from Banff to Dingwall, and in a direction north to
south from Cromarty to Fort Augustus, may be estimated at
twenty; but it is probable that their actual amount will be
eventually found to be much more. Two vitrified eminences
appear near Huntly, connected apparently with the line of
coast extending from Kimnaird’s Head to the mouth of the
Dee. More south, a chain of vitrified sites, nine or ten in
number, appears to have conveyed signals from the line of
coast which stretches from Kincardine to the Tay, being pro-
longed from Stonehaven or Dundee to the neighbourhoed of
Dunkeld or Crieff. On the west coast, again, we find similar
vitrified sites at Bute, Cantire, Isla, Loch Etive, Loch Sunart,
Fort William, or at Arisaig. .The number which subsists on
the west yet remains to be ascertained ; about twelve have been
enumerated. Lastly, at Galloway, three occur, apparently as
signals against the marauding colonists of Ireland.

But it must be kept in -view, that it is highly improbable
that the original intent of the whole of these vitrified sites was
that of affording convenient localities for beacon-fires. ‘Chere
is no necessity, whatever, ceteris paribus, that signal lights,
merely giving notice of the approach of an enemy from the
sea, should be situated on fortified stations. It is not impro-
bable, therefore, that the rude ramparts themselves might, at
a still more remote period, have been erected by the oldest in-

| .
298 Dr Hibbert’s Observations on Vitrified Forts.

habitants of Albyn, namely, by the Caledonians and Picts;
and hence their occasional or very partial vitrification would
merely indicate the later use to which the eminences upon
which they were situated had been applied, when the Scots,
who succeeded to far earlier inhabitants, were called a to
repel new invaders from the sea.

Again, it may be remarked, that after the Northmen had
gradually acquired a permanent settlement in Scotland and
elsewhere, they themselves became liable to sudden piratical
descents from their own coutrymen; to guard against which,
ancient Sagas inform us, they instituted, in every country |
where their arms prevailed, still more perfect systems of
beacon-fires, the wardenship of which was enforced by the most
rigorous laws. Edicts on this subject appear in many early
codes of the north of Europe, particularly in the Leges Gula-
Thingenses of King Magnus of Norway, where, in the Land-
varnar Bélkr, we find that the bonds were plighted during
time of war to be prepared with watch-fires in places where the
same had been lighted up from old time. ( Magnus Konongs
Laga-Beters Gula-things-Laug. Havnie, edition, a. p. 1817,
page 85.) Martin also states of the ancient beacons of the
isle of Harris, which the Norwegians colonized, that ‘ there
are several heaps of stones, commonly called karnes, on the
tops of hills and rising grounds on the coast, upon which they
used to burn heath as a signal of an approaching enemy.
There was always a sentinel at each karne to observe the sea-
coast; the steward of the isle made frequent rounds to take
notice of the sentinels, and if he found any of them asleep, he
stripped them of their clothes and deferred their personal pu-
nishments to the proprietor of the place.” | Still more informa-
tion on this subject, yet of a general kind, may be found in
the “ Historia de Gentibus Septentrionalibus,” by Olaus Mag-
nus, whose narrative, “ De Ignibus Montanis Tempore Hos-
tili,” is accompanied with a rude drawing of mountain-fires.*

The explanation which Olaus Magnus gives of this drawing
is as follows: ** Ex hac imagine duo veniunt consideranda :
quorum alterum in vertice montium, fumi scilicet congestis

* A fac simile of the early wood-cut of Olaus Magnus is given in the
fourth volume of the Archeologia Scotica. .

"oso. eo

a yee a

Oe Te ae ey ae ace
. 4

jo es Va ,*, AL Ps a 2 a OY ae
~— .

Dr Hibbert’s Observations on Vitrified Forts. 299

lignorum struibus ad classicos insultus accedentium inimico-
rum arcendos excitati: alterum vero in littoralibus angustiis,
et scopulis, ne hostes insiliant, diligens equestrium custodia
intuenda: qui montana inhabitant loca tempore hostili, veluti
celerrimi speculatores, signa fumo faciunt: quibus visis, alii
reliquos montes incolentes, itidem a longé positis ignita pyta-
mide demonstrant, ut quilibet armatus juxta numerum princi-
pis, et patrize lege decretum, ex campestribus locis pro litto-
rum custodia sine mora descendat. Inter quos velites eques-
tres celerrimi adsunt, ut hostibus portuum, vel riparum ac-
cessum preeclusuri, sagittariis plebeize multitudinis locum sta-
tuant, ubi commodius excipiant, ac conficiant hostem, omnino
aggredi contendentem: ut scilicet in vallibus, aut cavernis
expectent, vel ad iniqua et ignota hostibus loca, quasi fugitivi
declinent, ne forté eos taliter insequentes educere valeant in
agmina robustiora: que urgente necessitate, usque ad infini-
tam multitudinem augeri solent. Nec desunt exploratores
quoque versum emissi, qui renuntiant, qua ex parte adhuc
immineant hostes, ut his celerius, et copiosius occurrentes, vel
consilio, vel virtute, vel insidiis, vel necessitate, vel despera-
tione, vel loci securitate nutantibus, ne dum victoriam adimant,
sed et victos, ut imperata perficiant, militari lege constringant.”
(De Gentibus Septentrionalibus, &c. edition, Rome, 1555,
p- 228.) :

Such is the account of these ancient mountain-fires which [
have collected from Olaus Magnus. By another writer, it has
been related of the Norwegian Monarch, Haco the Good,
that he caused large trees to be formed into piles, and to be so
placed as to be visible from mountain to mountain, with the
view that intelligence of a hostile invasion might in seven days
travel from one end of his kingdom to the other: ‘ Ut in
montibus excelsis ex ingentibus arboribus pyre ita struerentur
(s. angari) ut ab una pyra ad alteram facilis et liber esset pro-
spectus. Excitatus hoc pacto hostilis irruptiopis nuntius, a
prima in extremo regni ad meridiem angulo extructa pyra, ad
remotissimum boream versus publicorum comitiorum in Ha-
logalandia locum septem dierum spatio volitasse fertur.”
(Snorre Haconar Goda, cxxi. p. 146.) The quotation is to be

.
$00 Dr Hibbert’s Observations on Vitrified Forts.

found in Mr Turner’s Anglo-Saxons, vol. ii. p. 258, 4th _
tion.)

From this information of Snorro, we are entitled to expect
that vitrified sites should be found on the mountain tops of
Norwegian provinces. But I am not aware that Scandinavian
antiquaries have yet pointed out their existence.

Independently, hewever, of this historical testimony, most
of the vitrified forts which I have examined show internal evi-
dence of their having been in use for such incidental purposes
as beacon-signals. Where the stones which have received the
full force of the fires appear of inconsiderable depth, a com-
plete fusion of the part has taken place ; but, in other exam-
ples, the fused matter has run among’ the stones in small
streams. In almost every case vitrification appears in patches,
the cementing process not being a continuous, but a very he
mited effect. |

For the extent of fusion, we must look to the comparative
degree of frequency with which a beacon-fort would become
in requisition ; while the part of the fort which would be fused
must depend upon the direction of the wind at the time a
beacon was lighted. |

It is also not improbable, that such a portion of a beacon-
hill would be fired, as might convey the earliest information
of the direction in which an enemy was approaching, or of any
other events suggesting effectual plans of resistance. Thus,
at the hill of Cowdenknows, on the borders of Berwickshire,
although its summit has been fortified, it is on the flank of
this eminence, where little or no defence appears, but which
commands the view of a considerable tract of country to the
north and north-east, that a small cairn of vitrified stones is to
be detected. In many other places, also, vitrification is rather
_ to be observed on the unprotected side than upon the defend-
ed summit of a hill; which circumstance might lead us to sup-
pose, that signals of alarm were often intended to be conceal-
ed from an invading enemy, with the design that a readier
chance of success might be afforded to stratagems of repulsion or
surprise. That this view is not altogether theoretical, may be
collected from the very ancient armorial bearing worn by Mac- .
leod, Lord of Lewis, where, in a ruderepresentation given by Sir

9

~~ <{_ -s

Dr Hibbert’s Observations on Vitrified Forts. 301

David Lyndsay, Lyon King at Arms, in 1542, fires are made to
blaze from many diversified points of a beacon-hill. But the au-
thority of Wallace, who wrote in the year 1700, is more direct
to the point. He hasstated, that even at this late period “ the
people (of Orkney) had in every isle a wart-hill or ward-hill,

_ which is the most conspicuous and elevated part of the isle,

on which, in time of war, they keep ward ; and when they see
the enemies ships approaching, they put a fire, thereby to give
notice to the adjacent isles of the nearness of the enemy, and
to advertise them to be on their guard, or to come to their
help; this they distinguish by the mwmber of fires.

Gthly, Are there any other very ancient observances or cus-
toms, not hitherto cited by authors, which may have contri-
buted to this vitrification } ?

As it remains yet to be proved that marks of vitrification
are uniformly limited to fortified sites, or even to beacon-hills,
a natural question arises, “* Are there any other ancient ob-
servances or customs which might have contributed to this vi-
trification ?” |

For such information we must consult the earliest and most
obscure records of Scottish history. One of these which may
be noticed, is the public festival said to have followed the la-
bours of the chase, in the commemoration of which all the early
Scottish traditions and songsagree. That this feast was accom-
panied by a sacrifice of fuel derived from the ancient forests of
Scotland, to an amount which at the present day is almost in-
éredible, might be inferred from the testimony of Ossian, if we
could only depend upon the correctness of the translation: —
«* Night is around the hero and his thousands spread upon
the heath ; a hundred oaks burn in the midst; the feast of
shells is smoking wide.” But upon this cause of vitrification
it would be imprudent to insist, as I should be disposed to at-
tribute to it very few effects in comparison with that of bea-
con-fires. I shall merely mention, that in a section which was
made by Sir George Mackenzie of the very small vitrified fort
of Dun Fian, near Inverness, the quantity of burnt bones of
animals, and of charcoal, found on the site, would rather in-
dicate the sequel of a feast than the effect of signal-fires. But

302 Dr Hibbert’s Observations on ¥ itrified Forts.

perhaps a combination of events might have otoutned ta. pro-'

duce this appearance.

Nor is it quite impossible, that some few occasional instances.

of vitrification in particular sites might have been rather indi-
cative of the forest-trees that blazed during the immense:

feasts which the Vikingr were accustomed to enjoy upon each

occasion of a strand slaughter ; that is, when they assembled
near some strand or shore to slaughter the cattle which they
had captured, for the purpose of transporting the salted car-
casses to their winter haunts.

Another ancient observance connected with the lighting up’

of immense fires, was the festival in honour of Baal, which
was renewed upon each return of the summer solstice. This
was the greatest feast of the ancient inhabitants of Scotland,
which even long outlived the introduction of Christianity ; no

ceremony belonging to it being subsequently omitted, except

the sacrificial effusion of human blood. Indeed, the custom
of the Baaltein is perpetuated in some few districts to the pre-

sent time ; and at the parish of Galstone in Ayrshire, a simi-

lar pagan honour characterizes the feast of a Christian Saint, —

the ancient custom being still retained of kindling fires on all
the neighbouring heights upon the evening before a celebrated
fair is held in honour of Saint Peter.—(Statistical Account of
Scotland, vol. ii. p. 82.) (

In short, we have only to conceive of an annual hunter’s

feast, a Baaltein, or indeed a periodical bonfire upon any pub-—

lic occasion whatever, continued for many centuries in an ac-

customed site, and during a state of country in which it was —

deemed patriotic to reduce the luxuriance of extensive forests,

and we have a cause perfectly adequate to explain many in-

stances of vitrification, which, I expect, upon inquiry, will be

found to be of far greater frequency throughout Scotland er |

has hitherto been suspected.

Tthly, The probability that many of the sites in which vie

trified remains occur, were places of rendezvous for tribes *
clans, upon all public occasions of peace or warfare.

Should this supposition be admissible, it might possibly ex-
plain the circumstance of some vitrified sites boasting little or,
no defence.

4

*

Dr Hibbert’s Observations on Vitrified Forts. 303

In fact, places of rendezvousfor tribes and clans upon any pub-
lic occasion, alike incidental to a state of peace or warfare, must
have been suggested by many circumstances, as, for instance,
by the custom of holding justiciary courts upon them, or even
by religious veneration ; the first of which motives recom-
mended a cairn in the holm of Dalmorton as the rendezvous
of some Ayrshire tenants, (Statistical Account of Scotland,
vol. ii. p. 594,) while superstition taught the Buchanans to
gather in the island of Clareinnis in Loch Lomond. Keeping
this circumstance in view, we need not be surprised that vitri-
fication, which was as likely to result.from festive or religious
bonfires, as from beacon-signals, should appear in a holm or
islet of the Kyles of Bute,- not elevated many feet above the
level of the sea, or upon some inconsiderable eminence of the
easiest access to an assailing enemy, which is the distinguish-
ing site of Dun Fian.

Most places of rendezvous, however, were jaiplotod by de-
fensive motives. Thus, the ancient war-cry of the Campbell’s
in allusion to their assembling place, was the famous. moun-
tain in Argyleshire of Bencruachan ; while, among the bor-
derers, that of the Logans was Lesterich Law. . And, in the
use which we would make of these analogies, we-may cite the
vitrified fort of Dunardile, near the fall of Fyres, where, ac-
cording to the etymology given of the name by a statistical
writer, Dun signifies a hill; Ard, high; and Dyil, Carnochs
or followers of a tribe. (Statistical Account of Scotland, vol.
xx. p. 38.) In short, the sites of many forts, vitrified or un-
vitrified, instruct us, that, while they were intended as places
of rendezvous for tribes, their ramparts afforded no less a de-
fence for cattle than for human inhabitants; and upon many ~
of these Duns, or strengths, of inappreciable age, the fire of
the Beltein, or the beacon of war, has been in turns the symbol
for the gathering of ancient clans.

At the same time it must be remembered, that in some in-
stances a clan has had one site for its rendezvous, and another
for its beacon-hill. ‘Thus, in comparatively modern times,
the Seaforths mustered at the Castle of Donan, while the sig-
nal fires were lighted on the summit of Tulloch-ard.*

* Remains of similar observances may be traced in England even so
NEW SERIES, VOL. V. NO. Il. OCTOBER 1831. U

304 Dr Hibbert’s Observations on Vitrified Forté,

Sthly, The ancient densely wooded staté of. Scotland, ‘of
which, the number of vitrified sites, and the occasional:
pos extent of their vitrification, serve as indications:* <\ e+
The. forests of Scotland, from the -fifth'to the: Pits.
centusy, far exceeded in abundance or: magnitude those of
South Britain. Among the produce of them are. enumerated
the oak, the pine, (pinus ‘silvestris or Scots fir,) the’ birch,:the
hazel, the broad leaved or Wych elm, the roan tree, (or mouns
tain ash,) the common ash, the yew, the alder, the! trembling
poplar, (populus tremula,) the: bird. cherry, ai ares ee
and the saugh or sallow.: «.
Mr Fraser:Tytler has collected from: the Rota Scotia th
following list of ancient forests: [ ols Ip galat
The forests of Spey, the forests of Alnete, Tn ois
Kilblene, angmorgan,: Elgin, Forres, Lochindorb, and In-
verness. ull lo oie wee
- In Aberdeenshire, the forests of essai @aodenache Drum.
or Drome, Stocket,: Killanal, Sanquhar, Tulloch, Gasgow;
Darrus,: Collyn, and the new forest of Janne gomalig uk
- In Banff, the forest.of Boyne. . \. i athat
In Perthshire, a forest which, in David I? Ss iaigas ocenpicd
the lands between Scone and Cargill. 7
In Kincardine and Forfar, the. forests of Alyty Dry 7
and Plater. 1009

In Fife, the forests of Cardenie bind Uwwethy: 2050, saw
In Stirlmg and Clackmannan, extensive forests.: is voile Te
‘In Ayrshire, the forest of Senecastre.. 9 2 1 (00 4 om

In the Lowlands ‘the forests of Drumseleh near il ith
of Jedburgh, of Selkirk, of Cottonshope, of Maldesley, of Ets
trick; of ed eee of Dolar, of Tepes and bis, igi ok

“< rly to
late as the sth century. It is asked in ‘* the Sidoatiele Dialogusg? (edi-
tion a. p. 1738, p. 187,) ‘ To what place are you that are the tenants of
this manner usually called to do your services, to muster, and -to show
your armour ; and what beacons are you appointed to watch and’ ward at ?”

* Sonie few: additions have béen made to this section sinée this’ paper
was read. at the Society, in consequence of the information of which I
have lately availed, myself relative to the ancient forests of Caledonia, from
a chapter in Mr Fraser Tytler’s excellent History of Scotland.. For.seme
additions to my list of the earliest exon forest 7 I have to” Ee
my friend Mr Neill. weinnnee *

\

,
-
‘

Dr Hibbert’s Observations on Vitrified Forts. 305

forést, likewise, in David the First’s reign, covered the one
between the Leader and the Gala.

- Such.is the list-of the ancient forests of Scotland, withif “a
limits of which vitrified sites appear; and it is in vain to look
for them where luxuriant woods have not subsisted. In the
Orkneyinga Saga, for instance, we read of numerous beacons
signals having been lighted up in Orkney and Shetland; but
as these islands from remote historic times have been destitute
of forésts, no fire has beem raised of sufficient intensity to leave
any tnarks of: vitrification upon the mounds of stone'on which
the inflammable materials rested. *: ‘The sameremark may ap-
ply to some of the Western Islands. _Vitrification only appears
where such mountain-fires have blazed as Olaus a ie
described. |

. This. very wooded state of Scotlaind, which 4 was its pectiine
charanter during the period when its shores were the most ane
noyed by the predatory excursions of the Northmen, will also,
Ltrust, explain why: vitrified sites should be so common in this
country, to the exclusion of England, where, owing to the
more early: civilization of Saxon ‘colonists, forest lands were
beginning to be thinned, and where, from motives of necessity
as well.as convenience, the habit had commenced of using for
beacon-fires vessels riage with pitch, instead ce cae 9a —
of wood.) .

Keeping, then, hive ancient wonided state eof Sedélaal steadily
in-view, it is by no means illogical to extend rather than to
limit the causes which would induce our ancestors in a coun

try overspread with trees, where arable land was also much

wanted, to allow the spoils of dense woods and thickets to be

% kindled upon every occasion of rejoicing, of religious sacrifice,

or of alarm upon the approach of an invading enemy. All
the ancient histories and traditions accordingly agree, that the
most extravagant use was made of forest trees on every occa-

_ *- This, my /ate remark, that there are no vitrified sites in Orkney, I
have about a month ago corrected by the unexpected discovery of nunie~
Yous vitrified mounds at Elsness in the island of Sanday, of which a notice,
contained ina letter to Dr Brewster, is given in the succeeding article.
‘This discovery is calculated to set at rest the most important questions re=
Jative to the origi of these vitrified remains.—S. H. 4

306 Dr Hibbert’s Observations on Vitrified Forts.

sion to which their burning could be applied. Until the thir-
teenth or fourteenth centuries, Scotland was in the exact state
of Wales, Which called for the particular law of Howel Dha.
** There are,” says this. legislator, ** three causes of progres-
sion for salutation ; Jand brought into cultivation, festal games,
and the burning of forests ; and no person must obstruct such
salutation.”

In fact, the effects indicative of immense. viles of blading
forest trees, the vitrifyimg action of which would be heightened
by favouring currents of wind, as by a blast furnace of sur-

‘passing intensity, are most truly marvellous, oft-times appear-

ing to vie with the result of voleanic incandescence. . But the
phenemenon will admit of explanation.. The stones which are
vitrified generally consist of such materials as granite, gneiss,
mica slate, clay slate, or the older sandstones and porphyries ;
and these are rendered more or less fusible, in. proportion to
the felspar which they contain in their composition ;—potash
being an ingredient of felspar, occasionally to. the amount of
14 per cent. The stony fragments which have been subjected
to this vitrifying process often exhibit effects which are of par-
ticular value to the geologist, as they illustrate various circum-
stances connected with the agency of heat, in reference to rocks
of much theoretical interest, which all ordinary experiments of
the laboratory would fail in achieving. ‘Thus, I might men-
tion among the most interesting specimens which I collected
from vitrified sites, those which show that heat has the power —
of causing strata of sandstone to assume the precise character —
of the more crystalline laminz of gneiss, or of BP AE iy: iui

itself prismatic. *

* The most beautiful and perfect specimens of prismatic gneiss I found
some years ago among the vitrified ramparts of an islet (named the Burnt
Tsland) in the Kyles of Bute. They were small, being about 4 inches in
length, and about 4 an inch in diameter, being formed at nearly right angles
to the laminar planes of the rock.

Since reading this paper, I had the pleasure of observing, in ‘the cabinet
of M. Von Leonhard, the celebrated Professor of Mineralogy in the Uni-
versity of Heidelberg, several specimens from the vitrified sites of Scotland,
which he had collected for the geological information that they conveyed
to. him. of the effects of heat upon certain rocks. I also received a few
weeks ago the Heidelberg new journal entitled the ** Jahrbuch fur Mi-
neralogie, Geognosie,” &c. conducted by Messrs Von Leonhard aud Bronn,

Dr Hibbert’s Observations on Vitrified Forts. 307

The thirteenth or fourteenth centuries form the closing pe-
ried to which we must limit the data of vitrified’ sites. “The
English, in their expedition against Scotland, endeavoured to
clear the soil from its encumbering woods; and it is recorded
that, in an expedition of the Duke of Lancaster, eighty thou-
sand hatchets were heard resounding through the forests, which.
at the same moment were consumed by spreading fires. Last-
ly, as Mr Tytler has added, many districts were soon afterwards
brought into cultivation, and converted into fields and meadow-
lands. .

- After the period of the destruction of Scottish forests, it-
would be futile to expect that any records would indicate the
continuance of vitrifying causes. ‘The hill which, as a signal
of war, once proudly blazed with the lavish conflagration of.
stately trees, is now illumined with little more than a paltry
‘tar-barrel! Sic transit gloria mundi.

Recapitulation.—But these investigations I shall now close
by stating the conclusions to which I have thus far arriveds
ae are as follows :—

- 1st; That the notion that vitrification is the effect of dileane
igeiey, as well as the hypothesis which would consider vitri~
fication as the result of a regular fabrication for the purpose
of cementing stone walls, are conjectures equally chimerical:

2Qdly, That the theory of Lord Woodhouselee, that the con-
flagration of wooden ramparts by an assailing enemy might:
have produced the vitrification in question, is not established
in any single instance; notwithstanding the probability that
such a cause might have occasionally subsisted.

3dly, That the number of vitrified sites in Scotland is re-.
ferable to the fuel extravagantly consumed during its ancient
densely wooded state.

in the first number of which is an essay by the first-named gentleman upon
the vitrified forts of Scotland. The scientific professor has reposed upon
the theory of Williams, as revived by Dr Macculloch, which is, I believe,
the only one known to continental geologists. There are several valuable
observations of the writer on the effects of the artificial heat thus induced,

when compared with the result of volcanic energy upon rocks of similar
_ character. The resemblance, to which I have myself many years since
adverted in various papers which I have read on vitrified forts, is often very

striking.

°
$08 Dr Hibbert’s Observations on Vitrified Forts.

. 4thly, That if we are entitled to suppose, that in a period
of the history of Scotland’ when wood was most luxuriant, more!
than one ancient observance might: have ‘induced the vitrifica-
tion in question, we:are authorized:in the*expectation, that the
character of the sites, im which vitrification’ occurs will be found?
as diversified as the multifarious: national causes to ahha
effect: may possibly be ascribed) ~~ [ vt onmer oti Buy

« 5thly,: That some’ of the sites: where vinwificaithell is. eandl
were ancient places of rendezvous for tribes or clans upon any
ened occasion whatever of peace or warfare. | baal
» Gthly, That many vitrified’sites may from historical ‘and in-
ternal evidence be shown to have resulted from beacon-fires
formed by piles of wood,after the manner described: by Olaus

Magnus,:Snorro, and other northern writerss) 1) ©) “s¥ to
\Tthly;. That other public occasions, festive or religious, night
have given rise to the same effect of vitrification. (99 14!

8thly, That it would be as easy to show, from numerous ex-
amples, that most of the oldest defences'or Duns of Scotland —
exhibit no vitrification whatever, as that- when vitrification does
occur, it is not restricted. to the precise reed of an emt’
racterized by rude ramparts of stone. en Votes
+ Othly, That in'some instances the: vitwindineiets of stony'ma-
vetlialet is of «so small an extent, as to nearly elude the search
after it ; while in others itis of a continuity - trey ices
almost surpasses credence: ; uo dstp st
» 10thly; That, as ‘it cannot be proved thiat tie vitrification i in
question is“imevery ‘instance confined to fortified sites, the
term VITRIFIED. FORT %8 too ry the i of ‘errors
Aandy alias aes M
Lastly, 'That, as nothing caw be more sitinfactbriby establish?
ed, than that vitrification is an incidental, not a designed effect,
the name of virririeD Frorr may with much advantage. be
exchanged for the more comprehensive and untheoretical one of
VITRIFIED SITE, £) af

Dr Hibbert on the) Vitrified Cairns of Orkney; 309)

- .S¥Get of: ViwesiahaMeensis: 10 Hoe! ‘it of ail ete dasacn:
Arr. XVILIL.—Notice of the Discovery of very extensive Vitri..
fied Remains at Elsness, in the Island of Sanday, Orkney.,
: By. 8. Hrssert, Me D., F..R.S. E., &e.. In.a Letter to
oiDedBamswrtkReo. VF do lev wh Ye wenger eds of came
iw My Dear Siz,
To the communication which you’ have honoured’ me by in-
serting in your Journal, from the Transactions of the Anti-
, quarian Society of Scotland, T have now to make an important
addition. sea : cheb se "

_ In my observations on the theories which have been pro-
j posed to explain the vitrified forts of Scotland, you will find it’
stated, that ‘¢ from the information of Snorro, we were entitled’
to. expect that vitrification would be found on the mountain
tops of. Norwegian. provinces 3, but that I was not aware that
Scandinavian antiquaries had yet pointed out their existence.”

I also remarked, in another article inserted in the Arch@ologia

_ ~ Scotica, (vol. iv. p. 184,), that the establishment of such a fact
; would. throw. no inconsiderable light upon the history of Scot-
_ tish vitrification. , : | |
“The solution of this question I haye not yet obtained; but
‘during the Jast month; I have arrived at the knowledge that
vitrified. sites exist in the. ancient, Norwegian colony of Ork-

ney, which is quite as satisfactory. Oe Ee

_‘ During my visit to these islands, whence I am but just ‘ar-
rived, I must confess. that I had but little expectation to find’
in it such a confirmed vitrified site as { have‘now to describe.’
Having many years since explored Shetland, the sister pro-
vince of Orkney, and examined most of its ward or watclr hills,

_ without detecting any marks of vitrification upon them what-
ever; having also found in every topographical account’ of
Orkney which I have consulted, a perfect silence regarding the
existence of vitrified remains, I came to the coriclusion (cer-
tainly a precipitate one,) that it was in vain to look for vitrified .
sites where luxuriant woods had not subsisted; that although
we read in the Orkneyinga Saga of numerous beacon signals
having been lighted up in Orkney and Shetland, ‘yet that, as
these islands, from remote historic times, had been destitute of

310 Dr Hibbert on the Vitrified Cairns of Orkney.

forests, no fire had been raised of sufficient intensity to leave
any marks of vitrification whatever upon the mounds of stone.
on which the inflammable materials had rested. 3

This conclusion I must now: very materially qualify.
was in the museum of Mr Traill, of Woodwick, a scientific
gentleman, who has formed a very interesting collection of the
natural products of Orkney, as well as of its relics of antiquity,
that I observed some very large specimens of vitrified stony
matter, precisely like that which is obtained from vitrified forts,
and with which you are familiar. These, Mr Traill informed’
me; had been sent to him by Mr Urquhart of Elsness, in’
Sanday, who had obtained them from the ness or promontory
which imparts the name to his estate.

_ After these prefatory remarks, I shall proceed to describe
the vitrified site of Elsness. You must, however, excuse me
from doing more than giving you a very brief notice of it, as’
well as of the inferences, supported by historical documents,
which are to be deduced from the discovery. These details,
which would run to an unreasonable length, I have not yet
had leisure to draw up in aconnected manner. They will, m
the course of the ensuing winter, as a continuation of my for-
mer memoirs, be laid before the auib BNC Society of Scot-
land.

Elsness, lying to the south of ae island of Sanday, is a pro.
montory rather more than a mile long from north to south,
and about half a mile broad. It was evidently the stronghold
of a Scandinavian chief, one of the ancient sea-kings, being
dignified by the presence upon it of the remains of a burgh,
or circular fort, as well as of a large sepulchral tumulus, which
bears the name of Egmond’s How, and of a number of smaller
cairns ranged near it in a semicircular form, which, perhaps,
were likewise the ancient resting-places of the brave. Another
contiguous site, which, by means of a low continuous mound
of earth, is made to take the form of a large crescent, indicates
by this particular structure the place of a weaponshaw, or the site
where a tribe was accustomed upon any hostile alarm to repair
fully armed. Again, about three quarters of a mile to the north
of Elsness, close to the oi Fs church named Mary Kirk, may

,

Dr Hibbert on the Vitrified Cairns of Orkney. 314

be traced the limits of an ancient ting, where, in Pagan times,

the functions of the priest and | Ate ,
the judge were combined. _ ay
. But the most interesting 2 sy hy Marykirk

remains of which Elsness can
boast are the beacon cairns
with which it is studded over;
—many of these exhibiting
unequivocal testimony of a
vitrification quite as intense
as is to be traced in any vi-
trified fort of Scotland.

Semicircle of Earth
L£gmond’s How

Bay Elsness.

These round cairns, of which I counted more than twenty.
are from three to five yards in diameter, and elevated from tl
to three feet above the surface of the ground. The stone
fragments, of which they are composed, which had evidently
been collected from the beach, consist of what geologists would
name an argillaceous schist; being, in this instance, an equi-
valent of the Mansfield slate. Their fusibility they have chiefly
derived from the felspar, or rather the alkali, which they con-
tain. The bitumimous matter which may often be found to
enter into their composition, and which, if constantly present
would materially add to their fusibility, is but an he
occurrence.
_ Altogether, these mounds answer to the description given
by Martin of the ancient beacons of the Isle of Harris, another
early colony of the Norwegians: “ There are,” says this writer,
«< several heaps of stones commonly called Karnes on the tops
of hills and rising grounds on the coast, upon which the inhabi-
tants used to burn heath asa signal of an approaching enemy.”
Upon the possibility, however, of mere heather to produce
an effect, which I have been hitherto only disposed to attribute
to the combustion of large piles of wood, I will not. yet give
an opinion. Wood is only found in Orkney in a fossil state,
that is, buried in peat; and whether this substance was em-
ployed, or peat itself, which is by far the most abundant fuel
in Orkney, or dried sea ware, or heather, or a mixture of two
or more of these combustibles, I am not now prepared to dis.

*
312° Di Hibbert on the Vitrified Cairns of Orkney!

cuss; but shall merely retnark, that the result produced upon!
the loose stones, whi¢h in the form of cairns supported the fuel,
is most astonishing. In some instances, the vitrification has ex-?
tended to:the very bottom of a cairn, showing an almost entire
compact mass. Nothing, in short, can display the effects ex-:
hibited mote satisfactorily, than by contrasting them with the!

appearances induced on subjacent stones by the fires of ‘the

kelp-burners of Orkney ; where, if vitrification is at) all -pro-
duced, it is slight in the extreme, and rarely cements stonesitor
an extent exceeding a few inches. ° This difference would inz
dicate that a vitrification, in order to be considerable, mist be
a work of time, demanding that the same cairn for perhaps‘a?
century or more should be the unvaried site on which beacon

=]

ates were kindled. . one
“ "The cairns of Elsness are not, however, all vitrified aikes

On ‘some of them I could ‘not detect a single burnt stone)
while in other instances a cairn would almost put ‘on the aps

pearance of one compact’ burnt’ mass. ‘'T’oo many’of them also.
were concealed by a thick sward; so' that their character for

vitrification still remains indeterminate. WBS 90) dod ihe
~- Such is the interesting vitrified site of Elsness, whicli I was
as gratified in explore, as upon finding that’ the rescue of its
cairns ‘from the unfortunate state of dilapidation, to which too
many Orcadian antiquities have been subject, has been duesto
the very intelligent proprietor, John Traill Urquhart, Esqoof
Elsneéss, who, desirous of ascertaining their origin, ‘and fully
aware of their importance to the archzologist, had given strict
orders for their preservation. ‘Previous' to these injunctions;
Mr Urquhart informed me, a‘ number of these cairns, during’
the process of ploughing up an 578% corn ge - been
rooted: up and levelled. : boat QnRd

With these particulars of the actual appearances presented —

at Hlsness,' I shall for the present content myself; and if any
theoretical advantage is’intended to be derived from them, it

must: be sought for amidst historical. as wellas local:evidence’s

but into this wide investigation’ F ain’ precluded entering; no
less on account of its length, than that it would /involve.details

which are more éaleulated for the pages of Antiquarian’Trans-.
actions than for your Journal. «LT shall therefore'dono more |

Ae

Dr Hibbert on the Vitrified Cairns of Orkneyl 1B

than! glance»at some of the conclusions to which I have ar-
v For‘three or four centuries, ‘that is: from the: 10th to the
14th, the Seandinavian province of Orkney, always impatient.
of the control of the «nother country, had noenemies to con=
tend with so formidable as the kings of Norway, who frequent
ly paid them hostile: visits; to ‘reduce them 'to° submission.

Against these incessant invasions the Orcadians were generally

_' well prepared “by keeping’ up a careful watch im their more

northerly ‘isles, which; upon. the first’ approach of anenemy
from the shores of Norway, should convey signals*to a*fleet
anchored in‘a convenient port, and ready to put’to sea; there
to contend with its foes long before they could possibly Jand.w
~« ‘These simple historical circumstances are abundantly unfolds
ed to us in the Orkneyinga’ Saga. Our inquiry, therefore; —
becomes comprised in the following questions; First, In-what

part of Orkney were its ancient gallies most’ commonly moors
ed?’ Arid secondly, In-what manner’ were timely signals cons
veyed to the fleet thus moored ‘to arm and put'to’sea?: © 101
« The first-of these questions is soon resolved: It is evident,

that, as hostile attacks were ‘chiefly to'be dreaded from the

north, the most northerly harbour’ whieh ‘could: afford’ good -
shelter and depth of water for ships, provided ‘also that «it
was situated on the east coast of Orkney, would be preferred 5
as these two circumstances of situation united, would be :requiz
site for readily clearing out to-oppose'a hostile fleet, advancing
in its proper course from Norway.» Now, ‘the ‘most: northerly
island, lying also to the east'of the Orkney group; is North
Ronaldsay ;—but here there isno harbour whatever. ‘Noriis
the island of Sanday, the next mm succession, much «more for:
tunate; its navigation being greatly obstructed” by ‘surrounds
ing shoals of ‘sand, uBence the ‘island has: derived its name,
In short, there is no port’ whatever which could have afforded
any convenience to early war ‘ships; required upon: the ap-
proach of an inyading fleet to instantly put to seajy-more: north
than the sound of Papa Stronsa. . This’ harbour; then,’ which
lies due south of Elsness in Sanday, ‘being divided from iti by
a channel a league’ and a-half across,:.must, :fromnecessity,
have ‘been selected as the ancient Portsmouth» of Orkney:

314. Dr Hibbert on the Vitrified Cairns of Orkney.

No other situation could have been so eligible for instant em-
barkation intothe Northern Ocean ;—which superior advantage
is even acknowledged at the present day, by its being the only
harbour in the isles of Orkney which is deemed a convenient
one for the prosecution of the North Sea heb of the Her-
rin :
The site of the ancient Portsmouth of Orkney being thus
established, the next object which 1 have is to shew through
what medium telegraphic signals, which consisted of beacon
fires, were conveyed to the fleet thus anchored in the sound of
Papa Stronsa.

Shetland, which yielded a more willing obedience to Norway,
was frequently in league with this power against Orkney, and
as hostile fleets were often reinforced in the more loyal pro-
vince, the intermediate island, named Fair Isle, of difficult ac-
cess except to boats, was firmly retained by the Orcadians
and converted into their most northerly signal station. From
this site, an alarm fire, which would be first hailed in North
Ronaldsay, would be answered by its inhabitants kindling a
fresh flame in order that the ae might spread to Papa
Westray and Westray on the
west, and to Sanday on the south.
Sanday would propagate the
alarm to the fleet which was >.
anchored in Papa Stronsa, withs
particulars of the number of hos-%
tile vessels approaching the Or-
cadian shores. ‘These particu-
lars, as we are assured by divers
writers so late even as the time
of Wallace, was usually signi-
fied by the number of fires which
were lighted; and hence the
many vitrified cairns with which <
the signal station of Elsness in Z
Sanday now appears studded. z

In order also to complete the ~
efficiency of this telegraphic sys-
tem, every Scandinavian province

) Vitrified cairns
of Elsness.

Dr Hibbert on the Vitrified Cairns of Orkney. 815

had its laws whereby watchmen were placed at the various
wart hills of the country, as the Ward or Vord Hills of Ork-
ney were named, who were required, under the severest pe-
nalties, to be constantly on the alert to transmit a signal of
alarm to a fleet, or to the chain of beacons of which it might
form a link. Accordingly, to the north of the sniall island of
Papa Stronsa, a higher cairn than common, intended as a look-
out place, appears, with the evident foundations of a build-
ing near it, which, I have no doubt, was the residence of thé
watchman whose office it was, upon the fires of Elsness be-
ing kindled, to instantly warn the fleet which was anchored in
the contiguous sound.

The historical view which I have thus taken was familiarly,
yet beautifully, illustrated when I visited Stronsa. On the
opposite shore of Sanday several distinct kelp kilns were
lighted up, which were well calculated to impress the imagina-
tion with a number of beacon fires, while the fishing-vessels
then moored in the sound, like so many war ships, added a
show of reality to the illusion. The number of the fires I
could distinctly count. But the atmosphere was then clear.
Under different circumstances, I can account for the disap-
pointment occasionally expressed by the ancient Northmen,
that the signals were not sufficiently explicit. In the year
1136, a messenger came to inform Earl Paul that war ships
had been seen, but that it was uncertain whether the mcenbier
was ten or twelve.

This is the general history of the vitrified cairns of Elsness.
Yet I am still in doubt on one subordinate question, whether
a telegraphic signal of the number of hostile vessels approach-
ing, indicated by a corresponding number of cairns being
lighted up, was communicated by this promontory from inde-
pendent observations, or from signals transmitted from North
Ronaldsay,—in which latter case we ought to expect as many
vitrified cairns to be found here as at Elsness. I much regret,
on account of the inconstancy of the weather, making a very
hasty visit to this more northerly island. I was certainly shown
by the well informed factor of this place, Mr Scarth, many
cairns, the stones.of which were discoloured by fire, yet there
was none in which absolute vitrification was manifest. But I
have requested the proprietor of the island, William Traill, Esq.

°
316 Dr Hibbert om the’ Vitrified Cairns of Oring.

of W oodwick, from’ whom,-on. other occasions, I have received
much valuable information of. Orkney, to procure me. more de-
cisive satisfaction. In the meantime, I can only add, that i itis
highly probable that Elsness often derived. its information of
the exact number of approaching war ships from independent
observation ;, as. the highlands of. Sanday afford oe .
a a look out, station, as.North Ronaldsay. - -. .

After this. particular examination, I visited. th ell of Pu f
more common wart or ward hills of Orkney, but observed the
beacon cairns upon them to show little more than discoloration
from. fire, with the exception of one ward hill only,—namely, °
that of Sanday, which is situated about two miles north of
Elsness. Three of the éairns on this’ “— were considerably
yitrified.* | jay

The circumstance of sitrifiention being chiefly observable on
the beacon stations which connect themselves. with the mooring
of an, armed fleet, while a similar manifestation in the ward
hills| of, other islands of Orkney appears scarce, is-of no little
interest, and strengthens the conjecture, which is not altogether
uncountenanced by history, that, upon the numberless occasions
of invasion; from Norway, it was, much less, frequently, found
necessary to: alarm the country.at large, than to, confine the
signal to the fleet which was in readiness ; and that ward hills
were only fited when an enemy was likely to make, good. its
landing, or when it. became necessary from any. other circum-
stances to summon the whole of the islands to,take up arms. ,

Nor is it of less moment to. keep another incident:in view :—
that while Elsness from its peculiar locality was'in every way
adapted, by means of beacon fires, to communicate with the
fleet of Papa Stronsa, the comparative, lowness of the promon-
tory prevented its signals from being observed. by. an expedi-
tion advancing from the north ;—which fact, by the way, may
explain-many circumstances connected with the vitrified. forts
of Scotland. boitixtie

Such is the general history of the vitrified cairns of Orknens
which may serve to set at rest, I trust for ever, two questions
which have been agitated for more than half a century... The

* Since’ this communication went to press, L have received from ‘Mr
Traill ‘of Woodwick, vitrified poeta | from the nef of Bovcran ane
ney.-S. HH. 2

tat ea

Dr Hibbert on the Vitrified Cairns gf Orkney. 317

first is,—To what uses or observances. is the effect of. vitri-
fication attributable ?, While the second.is, To, what. people is

_ the effect attributable ?.In,a tone of confidence, therefore, we

are now entitled: to reply,—T hat Vitrification was, merely. inci-
dental to the fires which were kindled upon beacon. stations s
and that the people who in every country which they occupied
or colonized, organized pi of beacon oe were of Bea
a origin. =.

»You will also, my dear Sir, readily perceives: that the aise
cation of this conclusion to the theory of the vitrified. forts of
Scotland, (for I -do not rank Orkney as a part of Scotland
proper,) isa ‘most: important one. , But I would not enter upon
the disquisition here, which would. be only to. anticipate the
memoir on the subject which L owe tothe Antiquarian, Society
of Scotland, with whose encouragement my investigations .on
this subject have hitherto been: uniformly honoured, If you
will therefore accept my present crude 1 reerdonnaiis on this sub,
ject, I give them: to you as follows :— ;

First, That the vitrified. sites of Orkney not being dane.
terized; as.in Scotland, by the presence of stone ramparts, but
simply ‘by small cairns. upon which the fuel for beacon fires
had been placed, incontestibly shew, that a, beacon. station was
not of necessity a place of strength or defence. 7 vile

~ Secondly, That such of the ancient Duns or strengths of
Scotland proper, in which vitrification is found. to be.an occa-
sional. occurrence, belong to the oldest, fortified. sites..in the
eountry, and are referable to some of its earliest inhabitants,
probably to the Picts, who are supposed to be of German erigin:

Thirdly, That these ancient Duns, not originally vitrified,
indicate, by. their construction and extent, that they were used
by a people who had already passed from ‘the hunting to the
pastoral state; as they evidently comprehend in their design
the protection of cattle, with that of human defence.
“Fourthly, ‘That from the tenth to the fourteenth century,'a
considerable part of Scotland was overrun by the Scandinavians
under the various names of Northmen and Danes, who ) reci-
procally became themselves Jiable.to invasion from other pirati
cal tribes of the same northern: origin as themselves, and were
therefore induced to institute systems of beacon fires, in imita:
tion of those with which they had been familiar in‘ Norway. »

.
318 ~ ‘Mr Johnston on Vanadium.

Fifthly; That as in’ most instances the ancient fortresses of
Duns of the oldest historical period of Scotland, were continued
to be used as the gathering-places of clans or tribes, the same
were.most conveniently selected as the sites’of beacon fires ;
the ramparts of loose stones, which characterize such fortified
sites, serving the additional purpose of cairns on which the fuel
was placed. "7

And, sixthly, That the intensity of fusion exhibited on these
vitrified sites is no less referable to the forest trees which on —
such occurrences extravagantly blazed, than to the incessant
hostile invasions which caused beacon fires to be lighted. —

But while I state these my present conclusions, (for it is
possible I may yet make some little modification in them,) E
would not renounce the idea, that other public occasions, as,
for instance, the annual lighting up of the fire of the Belting,
might have assisted, though in a subordinate degree, towards
producing the vitrified effects, which continue to be the’ asto.
nishment of all who are conversant with their extent. =~

But I must now conclude, as my letter has already exceeded
the limits which I had at first assigned to it. The interest
which continental geologists have begun to take in the varied
effects of ignition which these vitrified sites display, has natu-
rally made them curious regarding their mysterious history ;
which circumstance is the only apology I can offer for making
your Journal on this occasion a medium of pure antiquarian
inquiry. In some future Number, I hope to render you
acquainted with the mineralogical observations of M. Von Leon-
hard on the specimens examined by him from the vitrified sites
of Scotland.—Believe me, &c. &c.

EpInsuren, Ss. Hiepwhsil d

August 30, 1831. : | og & ye

- —

Art. XIX.—Some Notices regarding Vanadium. . By JamEs
F. W. Jounston, A. M., &c. Communicated by the Author.
I. Process for obtaining it from the Vanadiate of Lead. _
The mineral which I have called Vanadiate of lead is a com-
pound of arsenic, phosphoric, muriatic and. vanadic acids, with
oxide of lead, and a small admixture of earthy bases,—the se-

Oe te

te noe Aa Ps ea ae bk, ne a aren aie tate ae tS
Mah oe HA Ls SNR om SSS 8 LOVE Mb

~ eR ee en ee ey

Mr Johnston on Vanadium. 319

‘paration of the phosphoric and vanadic acids quantitively from

_ each other is attended with difficulties which I have not yet

been able wholly to overcome. The metal, however, may | be

extracted by the following simple process: The minefal is dis-

solved in nitric-acid, with which it forms a yellow solution.
From this acid solution the lead and arsenic are thrown down
by a current of sulphuretted hydrogen. The solution is now
of a beautiful blue, and contains the vanadium in the state of

oxide. It is filtered and digested for some time in a gentle

heat to separate the sulphuretted hydrogen, and a trace of sul- '
phuret of arsenic remaining in solution. Evaporated to dry-
ness by a gentle heat, it changes from blue to green, and
leaves a beautiful deep red mass, which is chiefly vanadic acid.

This is boiled in successive portions of a perfectly saturated
solution of carbonate of ammonia. ‘lhe colourless liquor is
filtered while hot, and deposits on cooling a white crystalline
powder in minute prisms, which is a vanadiate of ammonia.
This salt may be further purified by again dissolving in dis-
tilled water and crystallizing. By exposure to the air it be-
comes after some days slightly yellowish, probably from the loss
of a portion of ammonia. Heated in the open air, this salt parts
with its water and ammonia, and leaves oxide of vanadium,
which, by a continuance of the heat, combines with the oxy-
gen of the atmosphere, and forms vanadic acid. The yellow
powder thus obtained fuses by an increase of temperature into
a deep red liquid, and crystallizes on cooling into beautiful
prismatic radiating needles, sometimes of a deep red, but ge-
nerally of a steel gray colour, and high degree of lustre. Fused
in considerable quantity in a covered crucible and cooled gra-
dually, it gives beautiful large purplish transparent crystals
transmitting a brownish light. These crystals are pure vana-
dic acid, mixed when blue or grey with more or less oxide of
vanadium. By heating the salt in close vessels or in an atmo-
sphere of carbonic acid, an indigo blue, or, when rubbed in a
mortar, a dark olive brown powder is obtained, which is the
oxide of vanadium. | bole

IT. Metallic Vanadium and its pr opienGee
I have not been able to effect the reduction of the oxide by
NEW SERIES, VOL. V. NO IL. OcTOBER 1831. x

320 ? Mr Johnston on Vanadium.

means of hydrogen gas. Berzelius, at a white heat, obtained
a slightly cohering mass, which he considered to be but imper-
fectly reduced. Both the oxide and the acid are reduced easily
when heated with potassium or sodium, with the evolution of
much heat and flame, but without detonation. But the metal
is easiest obtained by mixing the oxide, or the chloride prepared
by evaporating the muriatic solution to dryness, with oil, and
forming it into a ball. . This is placed in. a small charcoal cru-
cible—surrounded with powdered charcoal—placed within one
or two other crucibles, and heated to full whiteness for two or
three hours. By this process it is reduced, but not fused, being
in the state of a grayish, slightly cohering, powder. To pro-
cure it in a massive state, the oxide must be previously fused
in a platinum spoon, the crystalline mass surrounded with
charcoal and oil, and heated for several hours. The mass thus
obtained has a metallic lustre, and possesses the following me
perties :—

1. It is of a reddish-white colour, approaching to that of
bismuth, so hard as to be with difficulty affected by the file;
and brittle, giving, when rubbed down, a gravish powder.

2. It does not affect the magnetic needle, but is an excel-
lent conductor of electricity.

3. Heated. in the flame of a lamp before the blowpipe i ina
pair of forceps, or on charcoal, or to a full red heat in a plati-
num spoon, it burns with a visible incandescence, and becomes
indigo-blue or steel-gray, exhibiting on the surface traces of
partial fusion. It undergoes no further change unless the heat
be long continued, when it fuses into a red liquid, which on
cooling below redness contracts in volume, and shoots at once
into beautiful radiating star-like groups of acicular crystals,
occasionally of a reddish, but generally of a steel-gray colour,
and high degree of lustre.

4. Heated. to incipient redness in an atmosphere of oxygem
gas, it burns, emitting a brilliant reddish light, and is converted.
into an indigo blue oxide of a crystalline structure, which fuses.
with difficulty in a platinum spoon over a spirit lamp.

5. In chlorine gas it burns at a heat below redness, forming
a greenish yellow vapour, which condenses. into a deep brown-

Ma) Schisten oa: Fahidli: 321

ish red volatile liquid. As it escapes into the air the vapour
is decomposed, forming white fumes of muriatic acid and va-
nadic acid (?), which deposits itself in the form of a red crust
round the mouth of the tube by which the vapour escapes.
Confined in a moist receiver, it is changed into a muriate, and
a beautiful blue liquid is formed, which is a solution of the
egg in muriatic acid.

_ 6. Heated in atmospheres of sulphur and iodinig; it under-

goes no change.

7. In nitric acid it dissolves rapidly, with effervescence and

evolution of red fumes, forming a deep indigo-blue solution,

which, by spontaneous evaporation, gives an amorphous partly
steel-grey and partly brownish crust, which isa mixture of the

vanadic acid with theoxideof vanadium. Evaporated todryness

by a gentle heat continued till fumes of nitric acid cease to be
given off, it leaves a beautiful vermilion red vanadic acid,
which is slightly soluble in water and forms a yellow solution}
Heated further, in the open air, this red substance fuses into
the red liquid already mentioned.

8. Neither the sulphuric nor muriatic acids act upon it sen-
sibly in the cold, whether dilute or concentrated, and very
slightly even when aided by heat. ‘The oxide is dissolved by
both acids, giving beautiful blue solutions resembling those of
the salts of copper.

III. Distinctive Characters of Vanadium. +7
_ This metal is most nearly allied to chromium, and it cannot
easily be confounded with any other. It differs from chro-
mium as follows.

1. The protoxide of chromium is green and:insoluble in
water, that of vanadium is dark brown and soluble. - The deu-
toxide of chromium, or the compound of oxide and acid is
brown; vanadium appears to give a similar compound, which
is of a beautiful indigo-blue. *

2. Newly precipitated oxide of chromium dissolves very

* Sefstrém speaks of a green oxide, ( An. de Chim. Jan. 1831.) This I
have not obtained, unless, indeed, we suppose it present in the green so-=

lution occasionally obtained in acids, and which I suppose to be mixtures
of the blue solution of the oxide and the yellow solution of the acid.

322 Mr Johnston on Vanadium.

sparingly in solutions~ of: caustic and carbonate of ammonia,
.with a rose red* colour; the oxide of vanadium. dissolves easily
in ammonia, giving a translucent dark brown or olive solution,

from which it cannot be precipitated by alcalies, as oxide .
chromium can.

8. Both acids are red and Pi into a rill liquid ; but while

the chromic is changed at a higher temperature into the in-

fusible oxide, the vanadic, according to Sefstrém, parts with ~

a small portion of its oxygen, and crystallizes on cooling, as
already stated. /

4. The chromic acid never loses its ealonin, neither by gt

ing nor by combinations with the bases. A solution of the
vanadic occasionally loses its colour by heating; and forms,
with excess of base, colourless salts similar to the vanadiate
of ammonia, mentioned above. ‘The presence of vanadic acid
may be at once detected in any of these colourless salts or so-
lutions by a drop of nitric acid, which reddens the salt and
makes the solution yellow. The crystallized acid or bi-vana-
diates are not to be distinguished in colour from. the di-chro-
mates.

5. Both metals give volatile chlorides, but that of vanadituin,

as already stated. by Berzelius, (An. de Chim. xly. p. 332,) is .

not always coloured. If a mixture of a chromate and a chlo-
ride be heated with sulphuric acid in a tube sealed at the one
end, a beautiful red gas is given off, which condenses if the
finger be kept on the mouth of the tube into a beautiful red

s

~ So et
hat Te a

=,

liquid, A similar mixture of a vanadiate with a chloride heat- —

ed in the same way, gives a colourless gas.
6. Solutions of the vanadiates give, with the metallic cals

in general, precipitates resembling those given by the chro- _.

mates. The salts of lead and mercury form the most striking
exceptions. Newly precipitated chromate of lead is of a bright
yellow, which it retains when dry, forming the beautiful and
well known pigment. The vanadiate of lead, at first bright
yellow, is bleached by the action of light, and becomes occa-
sionally pure white. Were it plentiful, therefore, it could
never take the place of the chromate in the arts.

* Gmelin’s Handbuch, i. p. 845.

TS eS
‘ :

bn PRES

Oe OOO EIS Ea lt ly

=

ai ee swe ee oN
x ef yo"

Mr Johnston on Vanadium. 323

With proto-nitrate of mercury, chromates give a deep red ;
vanadiates a bright yellow precipitate. Both give with nitrate
of silver a ruby or vermilion red, differing only in shade.

- In these differences in the properties of these two substances,

- having towards each other so many and striking affinities, —

we have ample means both of distinguishing and of accurately
separating them from each other, should they ever be found
in combination: and though, as the number of simple bodies
with which we are acquainted becomes greater, the properties
of the whole group will more and more shade into each other,
yet the number of points in which these two metals disagree,
shows us there is yet ample room for an addition to their num-
ber without rendering the difficulties which oppose the analy-
tical chemist absolutely insurmountable.

' T have not proposed to myself the difficult task of collecting
materials for an entire history of vanadium and its compounds,
knowing it to be already in far abler hands. Berzelius has
been occupying himself with it during the past winter, and he
has in all probability already finished his researches; but so
little has yet appeared in this country regarding the new me-
tal, and it may be yet so long before the results of Berzelius
find their way to our journals, that I have thought the above
sketch of its properties might in the meantime not be uninte-
resting to British chemists.

An “ Old Correspondent.” in the August number of the
Philosophical Magazine and Annals, p. 157, mentions my hav-
ing found vanadium in an ore of lead from Alston Moor, and
suggests that it was more probably from the neighbourhood of

‘Keswick.—On this [ have only to remark, that I have never

found it, and never said it was to be found in any ores of lead,

‘except the two varieties described in the former number of this
Journal, page 166, as formerly occurring in a now r anwrougnt

mine at Wanlockhead.

PorToBELLO, 8th September 1831.

o

324 Professor Airy dn the Double Refraction of Quartz.

Art. XX.—On the Nature of the Light in the Two Rays
produced by the Double Refraction of Quartz. By G. B.
Airy, M. A. M.G. S. Late Fellow of Trinity College ;
Plumian Professor of Astronomy and Experimental Philo-
sophy in the University of Cambridge; and: Fellow of the
Cambridge Philosophical Society. (Abridged from the Cam-
bridge Transactions. Read February 21, 1831.)

I propose in this paper to offer some conjectures as to the
nature of the light forming the two rays produced by the
double refraction of quartz; to describe the experiments on
which they are founded ; and to explain the calculations by
which the theory and the experiments are compared. The
subject is one to which (I believe) no attention has been paid,
except by one distinguished foreigner; the mode of calcula-
tion is original to me, and is, to the best of my knowledge,
new. ! alata

It is well known that the rays produced by the double re-
fraction of calc spar, (calcareous spar, Iceland spar, or rhom-
bohedral carbonate of lime) and most other doubly refracting
crystals, are entirely polarized: one in the principal plane

passing through the ray (or, if a biaxal crystal, in the plane _.
equally inclined to the planes passing through the ray and the

two axes) and the other in a plane perpendicular to the for-
mer. From the exact agreement of the phenomena of depola-
rization with the calculations made on this hypothesis, we are
justified in supposing that the law holds true when the rays
are so little separated that it is difficult to observe them in. the
common mode of inspection. Now it has generally been sup-

‘posed that the two rays of quartz are polarized in the same —
way: differing from those of cale spar only in the magnitude —

and direction of their separation. 1t was known, however, al-
most as soon as Arago and Biot commenced their observations,

that there is some anomaly in the rays passing in thedirection of ©

the axis of quartz; and the latter of these observers establish-
ed the difference of right-handed and left-handed quartz.
Fresnel by a simple experiment, (see Note A.) (which I have
repeated) showed that the light in the direction of the axis of

Professor Airy on the Double Refraction of Quartz. - 325

quartz is not one ray, but two rays moving in the same direc-

tion, and with different velocities. He showed, moreover, that

anew kind of light may be produced ‘by causing polarized
light to undergo two internal reflexions in a glass rhomb with
certain angles, the plane of polarization being inclined to the
plane of incidence at an angle of 45°; and that this light is
exactly’similar to one or other of the two rays above-mentioned,
according as the plane of polarization is on one or the other
side of the plane of incidence. And by a mathematical inves-
tigation, of which I am unable to supply the deficient steps,
he showed that the effect of the internal reflexions is to retard
by one quarter of an undulation the undulations perpendicular
to the plane of incidence, so that in the light thus modified
the particles of ether which were originally in a straight line
wil] at any time be found in the form of a circular helix, and
each will revolve uniformly in a circle. (See Note B.) And
from the nature of the original experiment it appeared that in
right-handed quartz it is necessary to suppose the right-cireu-
lar polarization transmitted with the greater velocity ; in left-
handed quartz the contrary. I have repeated and varied most:
of Fresnel’s experiments relating to this subject, and am per-
fectly convinced of the correctness of his views.

Now if, in the experiment with the glass rhomb, the planes
of polarization and incidence be inclined at any other angle
than 45°, the magnitudes of the undulations parallel and per-
pendicular to the plane of incidence will no longer be equal:
but the alteration of their periods will be the same as before.
The displacement of the particles of either will still be repre-
sented by a helix, but instead of being traced round a circular

- cylinder, it must be supposed traced round an elliptic cylinder.

This modification may properly be called (as Fresnel has called

it) elliptical polarization. (See Note C.) This term has since

been used by. Dr Brewster to express thenature of the light (pre-
bably indentical with this, or nearly so) reflected from metallic
surfaces. Should any difference be found, I have no hesitation
in fixing on the modification above described as that to which
in ought in propriety to be attached.

I am now able to explain my conjectures on the nature of
the light in the two rays of quartz. |

-

.
326 Professor Airy on the Double Refraction of Quarts...

1. I suppose the ordinary ray to consist of light. elliptically,
polarized, the greater axis of the ellipse being perpendicular;
to the principal plane; and the extraordinary ray to consist of.
light elliptically polarized, the greater axis of the ellipse being
in the principal plane. o

2. I suppose that when the ordinary ray is righiecliipdaaliiee
polarized, the extraordinary ray is isficellipticaliinnmlartane
and vice versa.

3. I suppose that the proportions of the axis of the two alse
lipses are the same: each proportion being one of equality when,
the direction of the ray coincides with the axis, and becoming
more unequal, according to some unknown law, as the direction:
is more inclined to the axis: the minor axes of the ellipses hav-
ing sensible magnitudes when the one are inclined 10° to the
axis. '
4. I suppose that the course of the rays, after refraction. can,
be determined by the construction given by Huyghens for cale
spar, with this difference only, that the prolate spheroid for de-
termining the course of the extraordinary ray must not be sup-.
posed to touch the sphere for determining the course of the or-
dinary ray, but must be entirely contained within it.

These conjectures were originally suggested by the desire of .
finding some connecting link between the peculiar double re- '
fraction in the axis discovered by Fresnel, (see Note D,) and:

the double refraction commonly recognized. All the phenome-
na of colours which I have observed agree perfectly wie the re-
sults of my hypotheses.

I may mention that I have found observations pale

to many detached parts of the phenomena which I have viewed.

assembled, in the early memoirs of Arago and Biot. But the
method which these philosophers used, (particularly the latter,)
of examining a small part only at a time, does not appear to be;
well adapted to the,discovery of the laws of light. In the ex-
periments which I am about to describe, every thing depends
on the form of the coloured curves; and to attempt to discover
this from observation of detached parts would be perfectly hope~
less. These coincidences I have recognized only since I made
my own. observations.

It must be observed that all the shhenoniens mentioned below.

a
Boe SS

3. are

Professor Airy on the Double Refraction of Quartz. 327

are described as they appear when examined with an analyzing
plate of unsilvered glass. If a plate of tourmaline be used, the

right and left parts of the image will have the same relative: po-

sition, but the upper and lower will be interchanged :. the ob.
server’s eye being supposed to turn in such a manner that the
axis of the tourmaline appears wp and down.

Phenomena.—l. If a plate of cale spar cut perpendicular to-
the axis be examined with the polarizing and analyzing plates
crossed, the uniaxal system of rings is produced. If the ana-
lyzing plate be turned less than 90° either way round the inci-.
dent ray, the complementary system is produced. The order:
of colours does not sensibly differ from Newton’s scale, begin-
ning with black. ‘These are common and well known mae:
mena.

II. If Fresnel’s rhomb of glass be placed to receive the po-
larized light, so that the plane of reflexion pass through the divi-
sions 45° and 225°, the cale spar will present another appearance.
The rings are abruptly and absolutely dislocated: those in the
upper right hand quadrant and the quadrant opposite to it are
pushed from the center by one-fourth of an interval, and those
in the other quadrants are drawn nearer to the center by the
same quantity. ‘The line separating the quadrants is nowhere
black: the intensity of its light is uniform and almost equal to
the mean intensity. If the plane of incidence pass through —
135° and 315°, the phenomena of adjacent quadrants are exact-
ly interchanged. No alteration is made by turning the analy-
zing plate round the incident ray: the lines dividing the qua-
drants are always parallel and perpendicular to the plane of re-
flexion at the analyzing plate. (See Note E.)

III. If the plane of reflexion in the rhomb pass through 0°
and 180°, or through 90° and 360°, the phenomena. are precise-
ly the same, and undergo the same changes as those in Pheno-
menon I. If, while the plates are crossed, the rhomb be turned:
gradually from the position 0° towards 45°, the rings are gra-
dually changed, at first becoming (as far as the eye can judge)
elliptical, and then assuming the form represented in Fig 8, |

IV. If a plate of quartz, whether right or left-handed, be in-
terposed between the crossed plates, a set of rings is. seen. Ag
far as the eye can judge, the rings.are exactly circular, but there

328 Professor Airy on the Double’ Refraction of Quarts.
is no black cross, and the central tint is not black, but removed:

from it by a number of tints in Newton’s scale proportional to
the thickness of the quartz. Thus, with a thickness 0,48 inch,

the central tint is pale pink: with a thickness 0,38 inch, the’
central tint is bright yellowish green : with thickness 0,26 inch,

it is a rich red plum-colour : with thickness 0,17 inch: it is a
rich yellow.

The colours then appear to be nearly the same, , Meanenina
from the center, as in Newton’s scale, beginning with the tint
representing this central tint. At a considerable distance from
the center four dark brushes begin to’ be visible, in the same
directions as the arms of the black cross in cale spar.

V. Now (supposing the crystal right-handed), if the plate of
quartz be thin, and the analyzing plate be turned, the upper
part towards the observer’s left hand, a bluish short-armed cross

appears in the centre, (see Note F,) which on turning further

becomes yellow : and the rings are enlarged. On turning still
further, the cross breaks into four dots. 'The rings are no longer

circular, but of a form intermediate between a circle and a square,

their diagonals (as well as the cross) being inclined to the left of
the parallel and perpendicular to the plane of reflexion. See
Fig. 9. If the analyzing plate be turned the other way, there
is no cross: the form of the rings is changed from circular —
as in the former case.

VI. If the plate of quartz be thick, the dilatation of the rings |

and the change of form are all the perceptible phenomena. And
on turning the analyzing plate continually to the left, the rings
continually dilate, and new spots start up continually in the
centre, and become rings. If the crystal be left-handed, the
remarks on this and the last article apply equally well, suppos-
ing the analyzing plate turned in the opposite direction.

VII. If Fresnel’s rhomb be placed in the position 45°, and

the light thus circularly polarized pass through the quartz; on

applying the analyzing plate, instead of rings there are seen two
spirals mutually inwrapping each other as in Fig. 10. If the
rhomb be placed in position 135°, the figure is turned through
a quadrant. If the quartz be left-handed, the spirals are turned
in the opposite direction. ‘The central tint appears to be white.

With the rhomb which I have commonly used (which is of

ee ee

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cd hate seinen

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ee a . eeeee l S e . PN get ise aha dteed aaa
-~ 3 Toe CN ep ned TS ues

Professor Airy on the Double Refraction of Quartz. 329 -

plate glass, but with the angles given by Fresnel for crown
glass) there is at the centre an extremely dilute tint of pink:
I think it likely that this arises from the error in the angles,
as the intensity of the colour bears no proportion to that in
other parts of the spirals. The figure was drawn from the ap-
pearances given by a plate of quartz 0,36 inch thick.

VIII. If two plates of quartz of equal thickness, but cut

one from a right-handed and the other from a left-handed crys-
tal, be attached together, and put between the polarizing and
analyzing plates, the left-handed slice nearest to the polarizing
plate, the appearance presented is that of Fig. 11. Four spirals
(proceeding from a black cross in the centre, which is inclined
to the plane of reflexion) cut a series of circles at every qua-
drant. ‘The points of intersection are in the plane of reflexion,
and perpendicular to it. This is the simplest way of describing
the form: but if we followed the colours which graduate most
gently, we should say that the form of each is alternately a spi-
ral and circular arc, quadrant after quadrant. At a distance
from the centre the black brushes are seen. If the combination
be turned so that the right-handed slice is nearest to the pola-
rizing plate, the spirals are turned in the opposite direction.
This is one of the most beautiful phenomena of optics. The
slices'from whose appearance the figure was drawn are each 0,16
inch thick.
_ [Mr Airy next proceeds to explain the mode of calculating
these phenomena on assumed laws of the nature of light in the
two rays of crystals ; but as this investigation occupies thirty-five
pages, intelligible only to the mathematical reader, we are ob-
liged to refer such readers to the original Memoir. ]

From the agreement between the observed and the calculated

_ appearances, I think there is little doubt that the nature of the

light in the two rays of quartz is such as I have described. I
do not mean to exclude the possibility of supposing that the
form of neither wave (in the construction for determining the
course of the rays) is exactly spherical or exactly spheroidal .

provided the difference of the forms be nearly the same as that
of a sphere and a spheroid. Nor do I mean to assert that each
elliptically-polarized ray consists exactly of two plane polarized
rays following each other at the interval of one-fourth of an un-

330 Professor Airy on the Double Refraction of Quartz.

dulation : or that the ratio of the two'axés in the two rays is
exactly the same. But I conceive it to be perfectly certain that
the general character of the light is such as is stated in my hy-
potheses.

I have not made any calculations upon other suppositions,
but I can hardly imagine that any other would represent the
phenomena to such extreme accuracy. I am not so much struck
with the accounting for the continued dilatation of circles, and
the general representation of the form of spirals, as with the
explanation of the minute deviations from symmetry, as white
circles become almost square, and crosses are inclined to the
plane of polarization. And I believe that any one who shall
follow my investigations and imitate my experiments, wil be
surprised at their perfect agreement.

There is one relation between the construction for dette
ing the course of the rays, and the nature of the rays, which de-
serves (I think) particular attention. It is that (comparing the
rays of quartz with those of any other crystal) a change in the
nature of the ray is accompanied with an interruption of conti-
nuity. The nappes of the wave surfaces are absolutely separated.
This is not the case in the common construction, for uniaxal
crystals, nor in Fresnel’s construction for biaxal crystals. There
may possibly be a connection of the same kind as that between
the change from partial reflexion to total reflexion within’ glass;
and the accompanying change from plane polarized light to el-
liptically-polarized light. The cases are at least thus far ana-
logous, that the change in the light and the interruption of con-
tinuity go together. But we are so much in the’ dark respect
ing the physical constitution of mane that we cannot at pre-
sent go farther.

It might have been dedieatid to verify my suppositions. by.
‘more direct experiments on the separate rays of quartz. I can
only plead that the duties of my office have not allowed me —
the necessary time. They would (under all circumstances) have
been: much more troublesome than those which I have the ho-
nour of laying before the Society: and I do not think that —
they would. have been more satisfactory. The appearances
presented by depolarization are admirably adapted to the’ dis-
covery of the most delicate differences in the nature and course

ee ae eee ee eS a Se
< 7

Pe ee ee ee ee eR

Pi Oe ag NT a

Professor Airy on the Double Refraction of Quartz. 331

of rays. .The same want of time I hope will be allowed as an
excuse for the want of accurate measures: without which, no

theory, however satisfactory in general explanations,can be con- _
sidered. as firmly established.

_ Note A.—it is not easy to make this experiment in a satis-
factory manner. If the axes of the crystals are not precisely
adjusted, several images will be seen. I have not succeeded in
obtaining two only, though I have made the others much more
faint than the two principal.

Note B.—As I cannot appreciate the mathematical evidence

for the nature of circular polarization, I shall mention the expe-

rimental evidence on which I receive it. 1st, The light when
received on an analyzing plate or tourmaline presents the same
appearance in whatever direction the analyzing plate is turned —
round the incident ray. 2d, The phenomena of depolarization
are the same in whatever direction the analyzing plate is turned.
3d, If the polarized light passes through two such rhombs
placed in similar positions, the plane of polarization is shifted
90°. 4th, If they are placed in crossed portions the plane of
polarization is unaltered. 5th, The phenomena of depolariza-
tion agree with the calculations founded on this supposition: in
uniaxal crystals, where the plane of polarization of one ray is
changed 860° in going round the axis, the alternate quadrants
are pushed in and thrust out one quarter of a tint: and in bi-
axal crystals, where the plane of polarization is changed only
180° in going round the axis, the alternate semicircles are al-
tered in the same manner.

. Note C.—If I might venture to fix on the discovery of Fics.
nel, which among all his wonderful additions to optical science -
appears likely to possess the greatest practical value, I should
select his invention of the mode of producing circularly-polariz-
ed or elliptically polarized light by internal reflexion of plane-
polarized light in glass or water. He has given us the power
of. producing light whose laws are as well known as those of
plane-polarized light, and which is more manageable, inasmuch
as it admits of degrees in its ellipticity. The beautiful geome-
try of Malus is forgotten when we think of the discovery of po-
larization: the far more valuable theoretical discoveries of Fres-

832 Mr Blackwall on a New Species of Lamprotornis.-

nel will lose their pre-eminence when put in competition with an
invention which enables others to make discoveries.

- Note D.—It does not appear, I think, that Fresnel had made

any distinct supposition as to whether the two rays in the axis
should be considered as the ordinary and extraordinary ray in
their ultimate state, or not.. From all that I could extract from

his Memoirs, I was always in doubt whether both the ordinary

and the extraordinary ray in the neighbourhood of the axis
ought not to be considered as divided each into two circularly
polarized rays.

Note E.—It is proper to mention that I had exhitiwed this
phenomenon to the Cambridge Philosophical ‘Society in the
spring of last year, long before the publication of Dr Brewster's
valuable Memoir in the Phil. Trans. for 1830, and (I believe,

but I do not recollect the date,) before its communication to the

Royal Society.
Note ¥.—This may be considered as the definition of riches
handedness of the crystal: and this observation gives the readi-

est means, with a thin plate, of determining whether it is right-

handed or left-handed. If the plate be thick, the easiest me-
thod is to observe in which direction the analyzing plate must
be turned to make the rings dilate.

OBSERVATORY, CAMBRIDGE,
Dec. 30, 1830.

Art. XXI.—Description of a new Species of Lainprotornis:
By Joun Buackxwatt, F.L.S., &c. Communicated by the
Author. ns

‘Tuere have been recently deposited in the Museum of the So-
ciety for the promotion of Natural History established in Man-
chester, two specimens of a bird belonging to the genus Lam-
protornis, which, notwithstanding it is one of the most superb.
species of its tribe hitherto discovered, appears to have escaped

the notice of ornithologists. The following description will

serve to convey some idea, though it must be admitted a very
inadequate one, of this highly interesting and beautiful bird :

a

Mr Blackwall on a new Species of Lamprotornis. 3358

Order, Jnsessores, Vigors,
Tribe, Conirostres, Cuvier,
Family, Sturnide, Vigors,
Sub-family, —————? .
Genus, Lamprotornis, ‘Temminck.

L. Vigorsii. Bill and legs black ; plumage soft, silky, and glos-
sy ; head, sides, and back of the neck, upper part of the back and
lesser wing-coverts bright green, tinged with gold; scapulars
and lower part of the back of a rich bronze-yellow; greater
__Wing-coverts, feathers of the spurious wings, tertials, and the
_ tips and upper part of the outer web of the primary quills deep
_. purple, relieved with violet, blue, and gold ; lower part of the

exterior web of the primaries dull green; inner webs of the
primaries and secondaries black, faintly clouded with purple,
those of the four longest quill feathers in each wing being
abruptly emarginated near their termination, a prominent point,
formed by the projection of the more elongated fibres of the
web, rendering the sudden transition in its breadth remarkably
conspicuous ; outer webs of the secondary quills black, with a
- bright. tint of bronze-yellow ; tail rounded at its extremity,
black, with a slight mixture of bronze-yellow above, particular-
__ ly on the middle feathers ; tip, and outer edges of the lateral
feathers purple, glossed with violet, blue, and green; upper
and under tail-coverts purple, varied with violet, steel-blue, and
green ; cheeks purple, tinged with green; throat and anterior
part of the neck and breast similar in colour to the scapulars,
but less brilliant; abdomen bronze-green, tinged with yellow ;
_ thighs and flanks purple, clouded with violet and steel blue ;
__ under side of the wings and tail black. Colour of the eyes not
known.

Total length, 11,4, inches; bill, from the point to the fore-
head, ;°;; from the point to the gape, 1,‘,; wings, from the
carpus to the tip of the fourth quill feather, 6;';; tail, 4,7 ;
tarsi, 1,4,; middle toe, including the claw, 1,4.

As the two individuals of the above species in the Man-
chester Museum were imported to this country from Brazil, along
with a considerable collection of skins of Brazilian birds, it is
possible that this elegant creature may be indigenous in South
America. I have no positive information, however, that such
is the fact; and M. Temminck, in treating upon the family to

.
334 Decline of Science in England. -

which it belongs, (see his Manuel @Ornithologie, vol. i. p. lv.
note (3),) remarks, that “ toutes les espéces sont de l’ancien
continent, le plus grand nombre d’ Afrique”

I have named this splendid bird-in compliment to that dis-
tinguished and disinterested naturalist, N. A. Vigors, Esq. who
politely directed my attention to it as a species new to ornitho-
logists.

_ In detailing those peculiarities of structure which characte-
rize the genus Lamprotornis, M. T'emminck says of the toes,
** interne soudé a sa base, l’externe divis¢é,” (Manuel d Orni-
thologie, vol i. p. lvi.) the very reverse of what is actually the

case. This error, which probably originated in inadyertency, —

has been recently repeated by a celebrated French zoologist ; it
becomes the more desirable, therefore, that it should be cor-
rected.

Arr. X XII.—Odservations on a Pamphlet, entitled; “© On the
Alleged Decline of Science in England. By a Forriener.
London, 1831, Pp. 33.” Accompanied by a Preface by M.
Farapay, Esq. F. R. 8., &c.

** It would be unwise in a foreigner to give an opinion on matters which
he cannot be expected to understand.”—Pamphlet, p. 16.

Tue present dispute respecting the Decline of Science in
England, presents to us the rare and almost ridiculous feature,
never before exhibited in literary controversy, of all the com-
batants on one side coming openly forward with their names,
and pledging their public characters for the truth of their facts
and statements ; while all those on the other side are anony-

mous assailants, fighting behind black crape, or discharging their

missiles from.the masked batteries of magazines and reviews.

Sir H. Davy, Mr Herschel, Mr Babbage, Sir James Souths

and Professor Leslie, have all lamented, in powerful and elo,

quent terms, the decline, and ineffective state of science in

England ;—and though their allegations have been deemed by

ignorant and interested individuals, injurious to the honour

of the country, yet not one man bearing the name either of a
- philosopher, or even of the lowest grade of authorship, has
ventured to place his name and personal character in opposition

..

ee ee ane yl a |
7

Decline of Science in England. - 335

to the able and honest and patriotic expostulations of these —
great men. Having expended their munitions of war in spe-

_ cial pleadings, in the grossest perversion of well known facts,

the heroes of the mask have. at last been driven to the expe-
dient of subsidizing a scientific foreigner... We regret to find
that so excellent and eminent an individual as Mr Faraday has
been the Chargé d’Affaires who has negotiated this loan of exo-
tic talent ; but though it is gratifying to sfind that he abjures
the idea of having by this act “ expressed an opinion on the
subject either one way or the other ;” yet it will be seen from
an expression in his preface, which we subjoin, that he has
more than identified himself with the author on the general |

question, however anxious he may have been to renounce the

heavy responsibility of having given an editorial sanction to
those severe animadversions on the Institutions of France,
and on the personal characters of her most distinguished phi-
losophers, which constitute so remarkable and so unpleasant a
feature in the present pamphlet.

“ The MSS,” says Mr Faraday, “ in English, of the following
‘“ series of arguments was sent me by the writer, an eminent
‘¢ scientific foreigner, in consequence of a few remarks in our
“mutual correspondence upon some recent publications in
** England. Without being considered as expressing an opi-
“< nion on the subject either one way or the other, I am still
<< desirous of placing my friend’s reasons before the public;
‘* not merely because no one can judge correctly who has heard
‘¢ but one side of a question, but also as a great literary curi-

_ osity; for all must allow that it is an extraordinary circum-

“* stance for English character to be attacked by natives and
«< defended by foreigners.

“<I have scrupulously refrained from altering the jathirtnige ;
“ preferring rather that a few quaint expressions should re-
‘¢ main than that so distinctive a characteristic should be lost.

“For the clearer comprehension of certain passages, I
“ ought to say that it has been in my possession at least four
‘* months. | | |

“< August 1831. — M. Faranay.”

When Mr Faraday remarks that it is an extraordinary
circumstance for English character to be attacked by natives
NEW SERIES, VOL. V. NO. II. OCTOBER 1831. 2 one

336 Decline of Science in England.

and defended by foreigners,” he-declares in his own name that
Sir H. Davy, Mr Babbage, Mr Herschel, Sir James South, :
Professor Leslie, &e. &c.. who maintain the decline of science,
have attacked English character, and he has thus unwittingly
let out the whole secret of the bitterness which a certain class
of scientific men have evinced in the present controversy. The
English character here referred to, must. mean the character
of those English philosophers who may be regarded as the re-
presentatives of English science, and who may be supposed
entitled to feel that its decline has been owing to their, indo-
lence or incapacity: But unfortunately for Mr Faraday’s al-
legation, the principal representatives of English science are
the very persons who are here supposed to attack English cha-
racter, and therefore Mr Faraday must mean that Sir H. Davy,
Mr Babbage, &c. have attacked his scientific character, and
that of the other individuals, who like him maintain. that
science has not declined in England. The question is there-
fore no longer one of fact but one of feeling; and we are pre-
sented with the singular circumstance of the principal. philoso-
phers of England maintaining and lamenting the decline of ©
their favourite sciences, while, generally speaking, some of the
philosophers of the lower class are asserting that their charac-
ters are attacked by the allegation, and that science was never
ina more prosperous and thriving condition. — If this question
were to be submitted to the scrutiny of an English jury, we
have no doubt that the testimony of Mr Babbage and his‘sup-
porters would be. received as that of men who sacrifice their
feelings of personal and national vanity in the great cause of
truth, while the evidence of their opponents would be rejected
as that of partisans, disqualified from judging of a subject in
which they had acknowledged their own personal characters _
to: be involved.

From Mr Faraday’s preface we now pass to the pamphlet it it-
self, the first, pages of which are occupied in expressing the
surprise of the author that, while it has been customary for
rival nations to assert their respective pre-eminence in know-
ledge, ‘* a disposition entirely different is observable among
“some of the most scientific men of England. They appear
‘bent upon undervaluing their own country, and. seem to
“‘ take a secret (not very. secret surely,) and certainly a strange

Decline of Science in England. | 337

<* delight im extolling to the skies the scientific excellence of
“ foreigners of every description.”
Overlooking the gross perversion of truth involved in the

_ expression that Mr Babbage and his friends have taken delight

in extolling foreigners to the skies, we shall have no difficulty

- in explaining to an English reader, how men’ passionately at-

tached to their country and to its scientific honour, may yet
point out the defects of its institutions, and give a salutary
warning of the decline of its literature and science. When a
man embraces every opportunity of abusing the institutions of
his country, and evinces a pleasure in extolling the superiority

_ of foreigners, while he expresses no wish to reform these insti-
- tutions, and to raise his countrymen in that scale in which he

considers them as holding a degraded place, it is not difficult
to determine the character, and appreciate the motives of such
a calumniator. The sharp-sighted public sooner or later
detect the fraud, and the intellectual felon, the robber of his
country’s name, is pronounced guilty of acting under irritable
feelings, disappointed hopes, or personal animosity. |
Mr Faraday and his anonymous friend will, we are sure,
save us the trouble of proving that Sir H. Davy, Mr Babbage,
and Mr Herschel, &c. do not belong to this class of persons.
They have, on the contrary, shown themselves to be men jea-
lous of the honour of English’ science, and we could prove
from their writings, and those of their supporters, that they
have nobly vindicated the claims of English pre-eminence
whenever they were assailed by the unjust pretensions of fo-
reign authors. Sir H. Davy was upon this point extremely
sensitive, and Mr Faradav ought to have been aware from his
personal knowledge of that bright ornament of England, that
a philosopher may admit the decline of science in his own

_ country, while he at the same time exercises a morbid jealousy

of the pre-eminence of rival nations. It was, indeed, this true
love of English science, this anxious desire to maintain its pre-
eminence, that led Sir H. Davy to deplore its decay, and la.
ment the indifference which the aristocracy and the government
of England have exhibited in promoting our intellectual glory.
Mr Babbage, and Mr Herschel, and Sir J. South, have been
actuated by the same noble and patriotic motive. They strug-
gled in vain to remove the defects in our scientific institutions,

>.
338 Decline of Science in England.

by their personal and individual exertions ; and appealed only ©
to public opinion when other means had proved unavailing,
The evil management. of the Royal Society, and its baneful ef-
ects upon science, were exposed, not to lacerate private feelings
or promote private ends, but to advance the character of an in-
stitution whose history was interwoven with that of the bright-—
est period of British science. | The decay of mathematical
and physical knowledge was pressed upon public notice, not
to depreciate the character of English philosophers, but to
raise them to new exertions to revive and extend the one, and
to raise and ennoble the other... The splendour of foreign ta-
lent was brought forward, not to derogate from the lustre of
British genius, but to exhibit the happy influence. of Royal
favour and of national institutions ; and the liberality of fo-
reign governments was justly placed in. painful contrast with
the shallow ‘and ignoble policy of our own, with its habitual
neglect of intellectual worth, with its exclusion of genius from
all the offices and honours of the state, and with its more than:
barbarous indifference to the true glory of a civilized empire.
Such were the undoubted motives of the reformers of sciénce,
and we have reason to know that many of its youthful, culti-
vators have not only justly appreciated them, but have con-
sidered the declining state of English science as a ground for
more strenuous exertions to. maintain the honour of the na-
tion. Many of our readers will probably bear testimony in
their own hearts to the existence of such a feeling, and we trust
that there is a numerous class of scientific men who will cherish.
the noble sentiments so well expressed by Mr Brayley. i in the.
following commentary upon Mr Babbage’s views, which seems.
to have been composed for the very purposes of our argument.
Tt oceurs in a well written work, ‘* On the Utility of the Knows
ledge of Nature, considered in reference to the General hie
cation of Youth.”—London, 1831. Wk
“¢ Strong representations,” says he, ‘ have of late been msde).
“‘ and among other competent advocates, by the consummate
‘¢ mathematician who now occupies the chair in the University.
“« of Cambridge, once filled by Newton, of the paucity, in this
* country, of high mathematical knowledge, as well as that of.
‘¢ interest in the more elevated pursuits of those sciences which
“ are immediately connected with it, such as astronomy, and

~~ a

Decline of Science in England. . @BS

‘the more recondite departments of material physics. Our
‘continental neighbours, as well as the philosophers of Ger-
** many and the north of Europe, have been held up as ex-
‘* amples for our emulation, in this respect, which, it has been
‘* stated, we must for the present be content to follow at an
‘humble distance. That these representations are found-
** ed in truth with respect to the particular branches of know-
*< ledge in question, cannot be doubted ; and that they should
“© be true, every lover of science in Britain will regret, while
“ he will feel himself called upon to use his most strenuous en-

** deavours to remove.this blemish from our national honour.”

These are the sentiments of a generous and unprejudiced
mind, which regards the sacred interests of truth as paramount
to all private feelings ; and we must request Mr Faraday, after
reading the above passage, to decide upon the respective merits
of those who repel all friendly admonitions and wholesome
truths as insults to their character, and of those who receive
them in simplicity of heart, and apply them to ane vee pur-
poses of personal and national improvement.

Having thus vindicated Mr Babbage and his friends from
the unwarrantable imputation of having “ attacked English

| character,” we shall proceed to examine the defence of English

science by a Foreigner. ‘This amiable individual has perform-
ed with admirable tenderness, the united offices of apothecary
and sick-nurse to scientific England.. When none of her own
faculty durst visit her in her decline, save ‘the few empirics
who have administered to her in thedark, our kind devotee, under

_amask, is conducted by Mr Faraday to soothe and to rouse the
_ deserted patient. Elixirs, moral and physical, ate plyed with ex-

quisite address,—morphium and henbane combine their narcotic
virtues, and new emollients and stimulants are extracted from
every corner of the materia medica. It is alleged, says he, from
the very chair of Newton in the University of Cambridge, that
mathematics, once the staple commodity of England, has
greatly declined, and Mr Herschel has dared to say, that in
this science, ** England has. long given over a hopeless race.” .
How can this be, when Mr Herschel and Mr Babbage are

both fitted to run, and when La Place has praised Mr Ivory,
and M. Arago praised Dr Young? ‘“ There is not the slightest
** reason for giving over the race as hopeless, whilst such men

°
340 Decline of Science in England.

“¢as Mr Ivory, Mr Herschel, and Mr Babbage, are in the full
“* force of their talent. In France, M. Legendre is very old,—
*« the venerable Lacroix has done more than any other living
“* man for the diffusion of analytical science ; we see no one at
“* present in France but M. Poisson who could enter the lists of
“the race. I do hoe perceive, I a it, the least uleioety
“« for giving it over.”

Here we have our author fairly drawn from his generalities
into a distinct proposition incapable of being misinterpreted.
He starts English mathematicians, of whom he considers only
THREE as fit to run, viz. Mr Ivory, Mr Herschel, and Mr
Babbage, against French mathematicians, of whom he con-
siders only onE as fit to run, viz. M. Poisson. In order to
make up this strange equation, he eliminates M. Legendre be-
_ cause he is old, and M. Lacroia because he has done more than
any other living man, and he leaves M. Poisson to strive single-
handed with the three English mathematicians. We now bee
_ the reader’s attention to the ignorance and unfairness of this
contrast, which is.as reprehensible as a piece of reasoning, as
it is unjust to the high merits of the French geometers.

Mr lvory, now approach ite the end of a brilliant career, is

just as much disqualified for pursuing analytical research as Le.

gendre or Lacroix ; and both Mr Herschel and Mr Babbage
havelong ago abandoned their mathematics, the one for astrono-
my, optics and chemistry, and the other for mechanics, so
that the English list of our author is already reduced to zero,
and his argument falls, self-destroyed, to the ground.

But what shall we say of our author’s knowledge, when he

assumes M, Poisson as the only French mathematician. Has
he not heard of Cauehy, one of the brightest ornaments of
France, and one who is likely to revive the age of Laplace
and Lagrange. Does he exclude Biot, Poinsot, Ampere, Puis-
sant, Prony, Navier, and Damoiseau, from the right of compet-
ing with the mathematicians of England ? He will doubtless re-
ply that many of these philosophers have chosen other fields for
the principal display of their talents ; but he knows well that
the same was the case with Herschel and Babbage, and he
ought, therefore, to have omitted their names on the aed
side.
So far for our author’s flattery of English dinate

ae an SE ee.

Decline of Science in England. 41

We think we may leave this point to Mr Faraday’s own deci-
sion ; and though we do not entirely agree with the low
opinion of our mathematical character expressed by Mr Ren-

nie, Professor of Natural History in King’s College, Lon-

don, in his Introduction to Montague’s Ornithological Dic-
tionary, yet we know, that such opinions are very generally
maintained by uuprejudiced, though possibly not very well
informed, individuals. ‘‘ The consequence of this leading-
“* string system,” says Prof. Rennie, ‘ is, that it has nearly
** extinguished the mathematical reputation of Britain, for-
** merly so high ; it being as impossible to make a Newton by
“ parroting the Principia, as to make a Milton by commit-
*“« ting to memory his Paradise Lost.”

Another singular argument of our anonymous opponent

deserves the special notice of the logician, and all dealers in
syllogism. :
_ © The names,” says he, ‘“ of Sir Humphry Davy and of
“ Mr Herschel are, of course, of the highest authority ; but
“it would appear rather strange, that any one should attempt
“ to couple those names with a complaint of a decay of science.
“‘ This sounds pretty much as if, when speaking of Welling-
“ton and Nelson, one would argue on the inferiority of the
*¢ British navy and army. ‘The mere mentioning of the names
** of Davy and Herschel, could furnish a proof that science
‘* was flourishing in that country which gave birth to these
“ highly gifted individuals.”

When this syllogism is iitiiieal quoad artem, it thus
stands. Sir H. Davy and Mr Herschel declare, that science

is declining in England; and they are persons of the highest

authority ; but they were both born in England, therefore
science must be flourishing in place of declining!! Now for
the illustration of the syllogism. The British army and navy
never can be inferior to those of other nations while we can
speak of Wellington and Nelson; therefore science never
can decline in England while we can speak of Davy and Her-
sche]. Upon these principles, we are led to the cheering con-
clusion, far more delightful than that.of the author, thaé
science and the army and navy never can decline in England,
because Davy and Herschel were born withim its’ limits, and
because we can always speak of Wellington. and Nelson. This

342 Decline of Science in England.

perversion of reasoning will appear still more prominent! y when
we consider that-science never can decline except in a country
where it has flourished, and which has given birth to great men;
so that the very circumstance which must necessarily have pre-
ceded the decline of science, namely, the birth of two great
men such as Davy and Herschel, is held by our author as an
irrefragable proof that science has not declined.

In order to follow the other arguments of our author, we
must explain the circumstances under which science om LA
said to decline in any country.

1. Science must decline by the death, especially the prema-
ture death, of one or more of its most eminent and active cul«
tivators.

2. Science must decline, when the principal scientific insti-
tutions of a country cease to be presided over, and managed —
by distinguished men, and are conducted in a slovenly routine, :
and in a way in no respect calculated to encourage genius or
promote the advancement of science. aM &

3. Science must decline when the sovereign and his mini-
sters take no interest in scientific pursuits,—when, in place of
establishing new scientific institutions, they destroy old ones,
—when the honours and offices of the state are conferred only
on military and naval merit,—and when those duties which
require to be discharged by men of scientific knowledge, are
entrusted to persons who have no other claim but those of fa
mily connections and political subserviency.

4. Science must be considered as declining in any country,
even when none of the preceding causes ewist, provided it is
making less progress than formerly in that country, either in
the number or nature of its discoveries, or provided its pro-—
gress does not keep pace with that of rival nations.

Admitting the most favourable views of the talents of Lit.
tish philosophers, and the importance of British discoveries, —
there is no upright:and well informed man in the community,
who will not acknowledge with bitterness and sorrow that
from all the preceding causes, science has declined, and is de-
clining, in England. The truth of this sad conclusion, which
has been fully established in Mr Babbage’s work, and in the
Quarterly Review for October 1830, will bhi’ from a oan
view of the subject.

“Decline of Science in England. 343.

1. The death of Sir H. Davy, Dr Wollaston, Dr Iwiund:
Mr Watt, Dr Marcet, Mr Gregor, Dr J ohn Murray, Mr
Chenevix, and Mr Smithson Tennant, within a short time of
each other, was almost a death-blow to English science, and
particularly to the science of chemistry ;. and it behoves those
who allege that science, and especially chemical science, has
not on this account declined, to favour the public with the list

_of those who fill the shoes of those great men, or of the young

aspirants after chemical fame, who hold out the promise of
placing themselves in the wide breach so unexpectedly effected.
In order to answer this argument, our learned foreigner re-
sorts to the following singular artifice, in which he uninten-
tionally admits its full force. :
‘* In chemistry,” continues Mr Herschel, “ the case is not
** much better. But to us foreigners it appears hardly just to

-** complain of the state of chemistry, when the losses of Davy

‘and Wollaston are still so recent. With the exception of
** Berzelius, whose mind, however, is of a quite different turn,
‘* we will ask Mr Herschel what continental chemist can be
** compared to the two eminent men whom England has to
**.lament ?”

Now this is a truly admirable counterpart to our saith
former reasoning. When he wished to estimate the condition
of French mathematics, he cuts off Legendre as old and infirm,
and therefore forming no fraction even of French talent ; but
when we wish to estimate the condition of English chemistry,
he will not allow us to cut off Sir Humphry Davy and Dr
Wollaston after they have been years in their tomb! Nay,
he insists that no foreign chemist but Berzelius can be com-
pared with them, and yet he will not permit us to bewail.their
logs as an immediate and irreparable injury to science.

When we maintain that science has declined in consequence
of the loss of such great men, we surely do not mean to un-
dervalue those whom they have left behind. . We, on the con-
trary, value them the more, and we implore, -with double
earnestness, their eminent successors, Mr Dalton, Dr Henry,
Dr Thomson, Mr Philhps, Dr Prout, Dr Turner, Mr John-
ston, and others, to come forward with new zeal, and call forth
new powers to restore chemistry to its wonted glory. As Mr
Faraday considers his character attacked by the allegation of

344 Decline ef Science in sia la

the decline of chemical science, it is in vain to pra ” his
individual patriotism. ge

2. The influence of sninitatitiina: whether universities or so- —

cieties, im promoting or retarding the progress of ‘science, is
universally admitted.. The author of the present pamphlet,
to use a proverbial expression, admits this ‘* with a vengeance,”
when he declares that the establishment of the Ecole Normale
in Paris, ** though of short duration, was perhaps of more wuti-
** lity towards the extension of mathematical knociaigie THAN
“ aLL THE Universitizs oF Evrove tocetser.” All that
Mr Herschel and Mr Babbage have written ou the low con-
dition of English mathematics, and all that we and others
have said of the inefficiency of our universities, sink imto in-
significance compared with this heart-stroke against the ho-
nour and the usefulness of these institutions. 'The author of

this sentiment, who certainly cannot be a professor, must, if
he quits his mask, keep at a respectful distance from Cam-

bridge, for if the corporation spirit of this university, when sub-
jected to the gentlest admonitions of its true friends, has al-
ready bled where it was not wounded, and winced where it
was not galled, what powers of wrath will it not deploy against
the daring author of this alarming truth, or the flagitious
fabricator of this monstrous calumny? That Cambridge,
backed by all the universities of Britain, and by. all the uni-
versities of Europe, has done less for mathematical science
than the short-lived Normal School of Revolutionary France,
is indeed an assertion calculated to excite the patriotism of the

most unpatriotic, and to awaken the nr of the most

phlegmatic Englishman.

In thus stumbling among our venerable institutions in pur-
suit of the Lucasian professor, our foreign mstructor blunders
out a series of the bitterest though well meant remarks.

‘** Most of the English institutions,” says he, ** seem of so pars —

** ticular a nature, and so blended with other subjects totally
‘¢ different from what exists in other countries, that it would
‘¢ be unwise in a foreigner to give an opinion on matters which
‘‘ he cannot be expected to understand. * * * *. But
‘this certainly is a principle firmly entertained on the con-

“ tinent, that the diffusion of knowledge is far better promoted —

*« by having the sciences taught in the universities by _jirst rate
4

«

Decline of Science in England. _ 345 —

“‘ professors than by any universitarian regulations.” But
notwithstanding these hard hits our author is such a lover of
things as they are, that he tells us ‘ that in this as in many
- other things the best plan seems to be to let things take their

‘¢ natural level and not interfere in every particular with legis-
** latory provisions.” He very soon, however, repents of this
toleration of abuses, for in a few lines, when he gets hold of
an abuse that he really understands, he seems pesglate enough
to have it rectified.

** It is generally understood,” says he, ‘* that there are ma-
“‘ thematical and astronomical professors both at Oxford and
“* Cambridge who seldom or never lecture, and who often do
*‘ not reside at all at the university. I am possibly blinded
** by continental prejudice, but to me this appears a glaring
** abuse, which elsewhere would call for a speedy remedy.”

Having his eyes thus opened by one intelligible abuse, our
author begins to see too sharply. He attacks the Duke: of
"Wellington in the most tender point, and levels a general blow
at the institutions of our country, which, if it is true, or even
approximates to truth, presages the speedy downfall of mighty .
England. If there is one feature in our institutions more noble
than another, or more flattering to our national vanity, it is.
the accessibility of high office to character and talent... It has
ever been our boast, and we trust it long will, that the hum-
blest individual may, by the force of education and character,
rise to the highest offices that a subject can fill—to the Archie-
piscopal Mitre—the Woolsack, and the Horse Guards. Our
author, however, believes and asserts the contrary.

“* Mr Babbage,” says our author, “illustrates his argument |
‘*< by asking what would have been the military renown of
*¢ England, if, with an equally improvident' waste of mental
** nower, its institutions had forced the Duke of Wellington
*‘ to employ his life in drilling recruits, instead; of, planning
“ campaigns?’ To this we might answer, omnis comparatio
** claudicat. But admitting the ‘simile, it would have been a
** great waste of mental power certainly, if the whole life of
*‘ the noble duke had been employed ‘ in drilling recruits ;
** but it must be remembered that the greatest captain of the
‘¢ Jast century, Frederick the Great, amidst all his various oc-
“ cupations, literary and political, always employed part of

346 Decline of Science in England.

“his time in that exercise which Mr Babbage deems so far
“ below the genius of a Wellington. Perhaps if the illus:
“* trious British commander had contented himself during the
“last years with superintending the discipline and drilling of
‘“‘ the Grenadier Guards, instead of figuring at the head of
“‘ government, he would have rendered an essential service to
‘‘ his country, not attended with a loss of that popularity
“¢ which was once so deservedly bestowed upon the conqueror
‘of Waterloo. But we cannot help remarking, that the ease
“ which Mr Babbage very justly reprobates actually exists in
“ England. If Lord Wellington had not been what he is,
‘“‘ the son of the Earl of Mornington, but the son of a farmer,
‘“a common soldier, like the present king of Sweden, Ney,
‘‘ Lefebure, Soult, Murat, Lannes, and similar men, he might
‘“‘ have been, according to the institutions of England, doomed
“ for life to the drilling of recruits, but he never eae
“* been an officer.”

On first catching the substance of this paragraph, it is diffi
cult to resist the impression that the author really united the
incongruous characters of a scientific and a radical reformer ;
and, but for the’ appendage of the responsible name of Mr
Faraday, we should certainly have regarded it as a hoax upon’
the credulity of Englishmen. The attack upon the Duke of
Wellington is most unmerited, and we think we speak’ the
sentiments of all parties when we say, that but for one impru-
dent demonstration against a great popular measure, his me-
rits as a statesman will bear a comparison even with his mili-
tary greatness. But how shall we reply to the astounding
charge, that the institutions of England are such that none but |
the sons of Earls can become even officers! Silence is the best
refutation of a charge so palpably untrue, and we shall only
ask our author how, under such a system, scientific men could |
either expect or obtain rewards. ro»

From the state of our Universities, of which we have alist
ed our author alone to speak, we pass to the state of our
Royal Society ; ; and we shall consider whether or not it has
suffered such a change as to lead to the inference that science
may on that account have declined. és

Within ashort period previous to the death of Sir H. ‘Dati
this distinguished individual filled successively the offices of

Decline of Science in England. 347

Secretary and President to the Royal Society. Dr Wollaston
in like manner filled the offices of Secretary, President, and
Vice-President ; Dr Young was its — Secretary, and Mr
Herschel was its Secretary. |

It was scarcely to be wondered at that the Royal Botley
was alleged to have declined, when death or resignation had —
deprived the institution of these its brightest ornaments. In
fillmg up these sad blanks, despair rather than sagacity seems
to have presided at the election. It might have been expected
that the salaries of three of these appointments should have
been given to some young and active philosophers whose in-
come, limited either by circumstances or by.a too generous de-
votion to science, required such an addition. But with a fa-
tality which marks a falling institution, the three secretary-
ships were conferred upon men. who, though in every way
estimable and respectable, had: never been particularly active
in original research ; and all of whom enjoyed good profes-
sional incomes. One of these secretaries, indeed, was so loaded
with pluralities that it required seven lines of Mr Babbage’s
smallest type to record their names; and another was actually
an officer of artillery on leave of absence from his regiment, and
who,also held the paid situation of scientific adviser to the ad-
miralty. Of such a state of things it was the natural conse-
quence that the rewards of the society were adjudged upon
- new and erroneous ‘principles, that its T’ransactions no longer
shone with original discovery, that its funds were devoted to
promote no scientific object, and that the managers of the in-
stitution, deserted by some of its brighest. ornaments, were
nearly, incapable of forming an opinion of some of the papers
submitted to their review. - Of subsequent events we forbear
to speak ; they have a tongue of their own which will soon
bring them into public notice.

If any person who peruses this statement shall refuse to pith
mit that the Royal Society has declined, and science along with
it; we would invite him, forgetting for a moment space and
time, to sit down, as we have done, at the same table with Ca-
vendish, Sir W. Herschel, James Watt, Maskelyne, Playfair,
Hutton, Davy, Wollaston, Y oung, and Chenevix, these mighty
dead, and then to-name the party of the muatty ee to
which he will invite us in return.

“re

e :
— 348 Decline of Science in England.

3. The supineness of the sovereigns and cabinets of England, —
and the indifference of the aristocracy to the great objects of
science, have been so fully treated in Mr Babbage’s book and
in the article on the decline of science in the Quarterly Review,
that we shall confine ourselves to a reply to the observations
on these subjects made in the pamphlet under consideration. —

Our author admits “* that Sir H. Davy’s remark, “ that the
** aristocracy may be searched in vain for philosophers,” may
“‘ be very just ; and it is indeed to be lamented.” He adds,
“‘ that noblemen, as the Earl of Macclesfied and the late Duke —
*‘ of Marlborough, do not find many imitators amongst the ©
*¢ English nobility.” Desirous, however, of finding some ex-
ception to Sir H. Davy’s observation, he afterwards remarks,
** that it must not be forgotten that the first poet of the age
‘«¢ (Lord Byron) rose to such literary eminence from a seat in
' the British House of Lords;” as if this had any thing what-
ever to do with the subject under discussion. ~** Perhaps the
** cause of this neglect,” he observes, ‘* may be traced to the
** circumstances that individuals moving in those higher spheres
“* of society may obtain those distinctions, (the honours of the
** peerage,) which are objects of honest ambition, at a more
* easy rate than by labouring in the field of science.” Tf this is
not a well merited sneer at our mode of conferring honours, it
indicates great simplicity and ignorance on the part of an au-
thor. He surely does not believe that any labours in the field
of science, however brilliant in themselves and useful to the
nation, could by any possibility obtain such honours; and he
cannot but know that the easy rate to which he refers is no-
thing more than the possession of great wealth, the exhibition
of military or naval prowess; the dominion over ‘rotten bo-
roughs, and the maximum of political subserviency.

But, notwithstanding all these admissions, the author will
not allow ‘ that’ science is therefore declining in England,
‘¢ unless it could be shown that the same reproach attaches to
‘¢ other classes of society.” He is of opinion that the English —
people are great patrons of science, * and that science has —
‘“‘ a better chance in England than elsewhere of securing an
“ honest independence to its possessor. Dr Wollaston,” he
continues, by his scientific exertions, procured himself that
“‘ pecuniary supply without which ‘the greatest genius and ~

Decline of Science in England. 849

* the ignorant are alike unable to support themselves. Now
** J will tell Mr Babbage, that in no country Dr Wollaston,
*¢ unassisted by kingly favour, could have been able to earn by
“¢ his scientific discoveries, that independence which gave him
** the necessary leisure to apply all his mental force to the
‘* pursuits of science.”

Our author here commits a mistake which we have found a
very common one, and which, therefore, requires to be cor-
rected. England is a wealthy, commercial, and manufactur-
ing country, and any person, whether a native or a foreigner,
who brings into her markets an article of trade which admi-
nisters either to our wants or our luxuries, is sure of disposing
of it to the best advantage. Dr Wollaston discovered the art
of rendering platina malleable, and long enjoyed the monopoly
of supplying this valuable metal. Hence he made a fortune
by it, in the same manner as Dr Solomon did by his Balm of
Gilead. Mr Watt made a fortune by the steam engine,
but many other persons have done the same who made no
great improvements upon it. In all these cases the fortune
was made by ¢rade, not by science, for if Dr Wollaston had
found his art in an old book on alchemy, or had purchased it
from a foreign chemist, he would have made the same fortune
which he did. Sir H. Davy’s far greater discovery of the
metals of the earths never obtained for him a single farthing,
because it had no commercial value.

But while the wealth of England will be exchanged for an
article of trade, whether it is the product of science or of
quackery, the laws and customs of England are arrayed against
scientific exertions. Had Dr Wollaston taken a patent for
his method of purifying platina, he would probably never
have made a farthing, and might have been reduced to po-
verty by so rash-an act. Had he generously presented his
method to the British public, and thus thrown a new trade
into the hands of the community, the government would never
have awarded to him either thanks, or honours, or remunera-
tion. He was therefore compelled, to the great injury of the
country, to keep his method a profound secret till he lay upon
his death-bed, and: but for accidental circumstances, it would
have perished with him. Dr Wollaston, therefore, made his
‘money in spite of his country, and solely because he could .

350 Decline.of Science.in England:

bring his invention into the market without carton the se. >
cret of it. ! Po»
There are few inventions, however, of such a natiogs ‘shat
they can be sold without disclosing the principle of their con
struction. Of these Dr Wollaston’s Periscopic Spectacles was
one- He was in this case compelled to secure it by patent
The patent was invaded by pirates, and he lost the just re-
ward of his labours. _ Now, in every other country in Europe;
this patent would have been protected, and though these
countries cannot boast of such extensive bazaars as London,
and could not have supplied so many purchasers for new spec-
tacles, yet it is easy to decide which of them would have
been the greatest patron of the inventor. As another proof:
that science is well rewarded in England, our author mentions
the case of Sir W. Herschel, who, he says, * left a handsome,
** and what elsewhere would be considered a large fortune.”
Does the author know that Sir W. Herschel’s fortune was
that of the lady whom he married? If he does, why does
he pervert truth, and if he does not, why does he write on a
subject which he does not. understand ? In continuance of our
last quotation our-author goes on fo say, ‘ |
“I know such countries where the high-minded Wollaston
‘“‘ might have been obliged to fawn and bow in the anteroom
“¢ of some lawyer in office, where his discoveries would have been
“ submitted to the examination and criticism of some official
“ underling; of having his writings and experiments appre-
‘ ciated by those who neither can conduct an experiment nor
‘¢ weigh the force of an argument ; and after submitting to all
‘ these indignities—after having felt the full weight of the in-
‘ solence of ‘office, he might have had the humiliation to see
‘ preferred to his just claims, the unceasing importunity, and
‘“‘ the shameless effrontery of the impudent quack, and.of the
‘* subservient sycophant. This, I will tell Mr Babbage, is the.
‘¢ real state of scientific men in those countries, whose manner of
‘“‘ managing scientific concerns he affects to rate so much above
** that of his own country, and nist exempla essent odiosa, we
“ might bring convincing proofs of the truth of our assertion,
‘* from the scientific history of almost every country in Europe.”
True as we doubt not this picture has sometimes been on the

- Continent, yet we will tell our author that it is, and has been
3

wa

wn

n

Decline of Science in England. 351

pre-eminently true of England, and that, if he wishes to see his
own description justified or even caricatured, he will succeed
only by submitting some important invention to the British
government. As an anonymous writer, he need not have serup-
led to give us a few of the exempla odiosa to which he alludes ;
but, however, numerous they might have been, we should have
neutralized them by counter statements of the most striking
kind. When Dr Anderson, disgusted at home, carried -his
flying artillery to the French government—when Fresnel suc-
cessfully submitted his improvements in light-houses to the
French board,—when Aldini, introduced his incombustible
dresses—when Humboldt persuaded the Russian government
to erect physical observatories throughout the Empire,—
when Hansteen received from the Storthing of Norway a large
sum for examining the magnetic curves in Siberia,—when
the Emperor of Austria, the King of Russia, and the King of
Saxony invited to the honours of their capitals, the seientific
associations of Germany,—was there in these acts any appear-
_ance of official insolence to genius and talents? We call upon
our author to vindicate his allegation by facts, and we doubt
not it will be found*that the cases referred to, were those of
troublesome speculators who abound in all countries.

But not only are foreign sovereigns the liberal friends and
patrons of indigenous science, their liberality, especially that of
the Emperor of Russia, nobly extends itself to other countries ;
and while we are writing these lines, we have learned the gra-
tifying fact, that his Imperial Majesty, has presented to George
Harvey, Esq. F. R. S. of Plymouth, through his Excellency
Prince Lieven, a magnificent diamond ring, as a mark of ap-
probation of Mr Harvey’s investigations on ship-building, as
published in the article wears sores in the moraine En-
cyclopeedia.

We come now to a painful part of our duty; to notice the
calumnies against French philosophers and French science, which |
the author has brought forward to neutralize the high admira-
tion which Mr Babbage and the author of the article in the
Quarterly Review have expressed of the genius and institutions of
the French people. He represents the ** wealth and dignities”
which Napoleon heaped upon Laplace as “ the price of shame
** and degradation ;” and he enumerates Lacepede,. Monge,

NEW SERIES, VOL. V. NO, II. OCTOBER 183]. Z

352 Decline of Science in England.

Berthollet, and Cuvier, among the philosophers, ‘‘ all of whom,”

he says, ‘‘ bartered their conscience for wealth and influence.”

He ‘afterwards adds, with additional bitterness, ‘“‘ Such men

as Laplace, Lagrange, Lacepede, Cuvier, and Fontanes, en-

‘‘ joyed certainly a high income ; the former were senators,

“‘ whose salary was 36,000 francs, or L. 1500; but it is a glar-
‘¢ ing error to call this salary an emolument of science. It was

‘‘ the price of the shame and degradation incurred by these
‘“‘ men for giving their silent vote and sanction to any of Napo-

“‘ leon’s decrees, however oppressive ; it was the price for which
“¢ the silence and connivance was bought of these mock commis-
“sions for the liberty of the subject and the liberty of the
“< press, which subsisted as sinecures during Napoleon’s reign.

‘“‘ Supposing the English ministry thought it their interest to

“‘ bring scientific members into Parliament, would Mr Babbage
‘“‘ consent to sell his vote and his conscience for a pension of
“ L,. 1200 or 1500? Still this was what La Place, La Grange,

‘* Lacepede, Monge, Berthollet, &c. constantly did, and we must

“* not expect to buy at a cheaper rate the honour and sa

“< of men of such distinction.”

Human nature shudders at such imputations upon men whose
names and characters have become the property of mankind;
and while we express our firm belief that they are false, we must
add also our regret that they should have received currency in
a pamphlet published in England, and edited by an English
chemist, who, honoured with a seat in the Institute of France,
owed to that distinguished body at least the homage of his
silence. This is doubtless the time when every patriot would
wish to draw closer the ties which are beginning to unite two
mighty nations, and we earnestly hope that every other feeling
will be extinguished but those which spring from an honourable
rivalry in promoting the best interests of our species.

Before quitting this branch of the subject, we must notice two
extraordinary mistakes of our author. He supposes that the
contribution of L. 2740 annually, by 685 members of the Royal
Society, is a subscription Sor the encouragement and benefit. of
science, and that it is a greater honour to be a member | of the
Royal Society. than a member of the Institute of France.

“‘ A very material. difference,” says he, * between the Royal
“* Society and the Institute, consists in this, that the fellows of

Decline of Science wn England: 358

‘“‘ the former pay for their admission, whilst the members of the
‘¢ latter enjoy a pension. Now, there are at present 685 fellows
‘© of the Royal Society, who used to pay about L. 4 a-year for
‘the honour of their fellowship, making in all an aggregate
“sum of L. 2740, or 68,500 francs. The members of the
“‘ French Institute receive, or received formerly, each 1500

“< franes, making 10,250 francs of the public money. Now, we
<¢ will ask Mr Babbage in which country the honour of belong-
** ing to the first scientific society is held in greater estimation,
_ ‘in that in which the fellows pay the honour with 68,000
“* francs, or those where they receive 10,250 francs, and the
‘* honour as an addition besides ?

** Mr Babbage favours us with a table of the costs of fellow-
«< ship of different learned societies; it would have been very
“< curious if he had stated the annual sum thus contributed both
“‘ by the English and French nations towards the encourage-
** ment and benefit of science; and from the result, a fair esti-
“* mate might be drawn in which of the two countries science is
** held in the greatest honour.”

He who subscribes L. 4 a-year to the Royal Society, receives
in return the Philosophical Transactions gratis, the pleasure of
attending the meetings of the Society, the soirées of the presi-
dent, the chance of belonging to the Royal Society club, and
all the advantages of a reading room and library, which is open
almost every day of the year from 11 a. . till 4 p.m., advan-
tages really worth more than the subscription. Nay, there have
been cases where booksellers have exerted themselves, whether
successfully or not we do not say, to obtain the title of F. R. S.
for their hack writers, and have considered the subscription as
balanced by the commercial advantages which it secured. ‘he
man must, therefore, be insane, who imagines for a moment that
such subscriptions are contributions to science. Nay, the sub-
scriptions are altogether expended in publishing the T'ransac-
tions, and in paying taxes to the government and other contin-
gencies, and are actually returned in another form to the pockets
of the members. 'The medals, &c. of the Society are all paid —
out of legacies left for the purpose, and the Society has never
assisted a single scientific man in carrying on experiments, and
has never appropriated its own subscriptions for any scientific
object. ‘The same remarks are applicable to the Royal Society

354 Decline of Science in England.

of Edinburgh,—with this difference, that it has on several occa-—

sions, though not on so many as it ought, devoted its funds to
promote important ‘scientific objects. We can assure our anony-
mous flatterer, that there is not one of the 685 members whom
he mentions who really conceives that he i is an cata or
benefactor of science.

With respect to the comparative honour of being a Fellow
of the Royal Society, and a Member of the Institute, we’ can
scarcely believe that the author is serious. Every person must
feel that it is an advantage to be a member of the Royal Socie-
ty, but none that it is an honour. ‘The indiscriminate admis-
sion of every applicant of respectable character who enjoys title,
possesses wealth, or fills office, and the strange but undeniable
fact that no persons but men of science find it difficult to be ad-
mitted, are circumstances which exclude all ideas of we
connected with the transaction. eth?

In the case of France, the honour of being an Avcnitmabinai
is so palpable, that it is universally admitted, and that honour
is certainly increased by its being accompanied with a salary.
In London the members purchase their place as a matter of
barter; in Paris the academician is purchased by the govern-
ment as a commodity valuable to the state. If our readers are
not satisfied with this view of the subject, we must bring the ar-
gument more home to their apprehension. Mr Herschel and
Mr Babbage consider the honour of being connected with the

Royal Society as so evanescent, that they have’ omitted’ the
‘* Ten pound a-piece letters” from their names. We may add

our testimony, that we feel no honour but much advantage from —

the connection ; and we request Mr Faraday sincerely to ac-
quaint his friend whether he feels himself most honoured by be-
ing a Fellow of the Royal Society or a corresponding pa se
of the Institute.

4. The fourth proof of the decline of science, namelyj'Wht
which is drawn from the actual state of science in this country,
opens up a field too extensive to be discussed at present. © It
has been partly treated under other heads, and'we shall only —
appeal to our readers whether Mr Herschel, and Mr Babbage,
and Sir James South,—or Mr Faraday anaits correspondent, are
best fitted to judge of the state of the physical sciences in England,

and which of the two parties are actuated by the purest and most _

|

Decline of Science in England. 355

patriotic motives in the opinions which they have maintained
respecting the decline of science. The motives of men are ge-
nerally not cognizable by human judgment ; but circumstances
often present themselves, in which motives are as palpable as
the actions to which they lead. 'When Mr Babbage, Mr Her-
schel, and Sir James South sounded the alarm of declining
science, did they sit down with folded arms to witness its de-
cay. On the contrary, they were, and still are, the most ar-
dent and active philosophers in England ; and, what is more,
they are all men perfectly independent in fortune, seeking for no
official emoluments, but generously devoting all their time, and
much of their fortune, to sustain and revive those very sciences
of which they have lamented the decline. The occupations and
the motives of these three great men are peculiarly under pub-
lic observation ; and though it is perhaps unfair to separate one
from the rest, we cannot but express our admiration of the no-
ble and unrivalled sacrifices which have been made by Sir James
South to promote the progress of astronomical science.

But who are the patriotic defenders of English science; the
panders to our national vanity, the calumniators of genius, who
represent our first philosophers as Firebrands, and ascribe to
disappointment, and irritability and faction, the warnings and
expostulations of the best friends of England? Let them stand
forth! let them unmask their persons! and let him especially
present himself to be scanned by the eye of truth, who dared to —
say to the philosophers and inventors of England, what the ex-
perience of every one of them contradicts, “‘ THAT THERE Is
‘© AMPLE WEALTH IN ENGLAND READY UPON THE SLIGHTEST
“HINT TO SUPPORT THE EXPENCES OF SCIENTIFIC INVESTI-
“ GATIONS.”

The last subject noticed by the author of the pamphlet under
review, is the subject of conferring titles on persons eminent in
science and literature. On this subject the author substantially
agrees with Mr Babbage, but he is so unwilling to entertain one |
opinion in common with him, that he contrives, even on this
point, to fall out with him by the way.

“« Among the means” says he “ of encouraging science in
«* England, Mr Babbage proposes the institution of § an order
* of merit. Does Mr Babbage imagine that Dr Wollaston or
‘*< Dr Maskelyne, or some such men, would have been more.re-

356 Decline of Science in’ England.

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66

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spected cither at home or abroad, if, like the Russian, they
had half a dozen of different coloured ribbons pending on his
breast? In almost every country where such distinctions exist,
one-half of the ribbons are given to Jobbing and patronage ;

and upon the whole, we believe that the institution itself has
an injurious tendency. Such crosses and badges are but too
often the price for which honour and conscience are bought,
These gaudy baubles are the hooks aud baits by which a prey
may be allured, which could not be taken in any other way.
The distribution of these distinctions must of needs belong
to government. How are its members to judge of the diffe.
rent degrees of scientific merit? How can a minister know
whether an astronomer is a deserving honest man, or whether
he belongs to that numerous class of forgers, cooks, trimmers,
&c. whom Mr Babbage so justly brands and vows to execra-
tion? Mr Babbage does scarcely allow to government the ca-
pacity of choosing its own scientific advisers,—How will it be
able to discern those who deserve the order of merit ? A well
meaning government, not wishing to indispose any body, and

attaching deservedly no great value to these things, gives
a decoration for the asking; or for the slightest reason or re- -

commendation. In this way such orders get at every body’s
button hole ; and it is not extraordinary on the Continent,
to see a sleight-of-hand performer, a fiddler, or a mountebank,
decorated with some foreign order. Farinelli, a celebrated

castrato, was decorated by the king of Spain with the mili-

tary order of Calatrava; Napoleon gave the order of the Iron

Crown, la cowronne de fer, to WVelluti, another castrato.

The consequence of all this must be naturally, that in such
countries where such distinctions exist, fools are very eager
to have them, and really meritorious men do not attach the
slightest value to them, and very often refuse them when they
are tendered. Thus the late Professor Van Swinden refused
an order offered to him by the king of Holland:

** But in England there can scarcely exist any pretext for
instituting such an order; there is no necessity that govern-
ment should expressly allow certain persons the permission
to wear a toy attached to their button-hole. The king of
England, if he be inclined to science, and wishes to yest its

professors with distinction; may confer upon them the ho-
‘

Decline of Science in England. 357

“nour of knighthood or of the -baronetcy, as his late royal
*€ brother has done upon Sir Humphry Davy, and as he him-
“ self very justly did, upon Sir James South. There can be
“ ‘little doubt, if once the calculating engine is brought to perfec-
“€ tion but that we are going to have a Sir Charles Babbage;
‘‘ and we must seriously lament, not for the sake of the men,
** or of that of science, but for the honour of government, that
“¢ we never had a Sir William Wollaston, a Sir Thomas Young,
“and a Sir James Watt.”

In this passage our author completely misrepresents Mr Bab-
bage’s views. Mr Babbage does not propose an order of merit.
He merely says, that it has been proposed, and he even states, !
almost in the words of his opponent, that if such an order ex-
_ isted, government would not be able to fill it properly in the |
present state of public opinion respecting science, as it might be.
Jilled up through the channels of patronage, and by the mere job-
bers in science. When an order of merit has been mentioned
it does not mean that there are to be ribbons and gewgaws
dangling at button holes. It is meant merely to say, that an
honorary title should be created for civil merit. Our author
’ is mistaken, however, if he thinks, as he seems to do, that Mr
Babbage and others have any desire for such titles. Respected
as they know they are by the great and good men of every na-
tion, they are satisfied that this respect cannot be increased by
an empty and tinkling syllable prefixed to their names. They
have spoken of the subject solely as an instrument for promot-
ing science ; and though they themselves, already in the meri-
dian of their career, ask no reward for what they have done,
and seek no stimulus to do more, they are yet sensible that
such titles and rewards are powerful excitements to the young,
and that philosophers as well as heroes may be formed by the
ambition of honours that are within their grasp.

It has been more than once stated by our author, and we
fear it is an argument addressed to vulgar apprehension, that
science cannot decline in a country which is still adorned by
many great names. We admit, and we do it with true pride,
that the temple of British science still possesses some of its
most ornamental pillars, but we look in vain for the massive gra-
nite which should fill up its noble outline. The ruins of mate-
yial grandeur read to us the lesson of our intellectual decline.

358 MacCulloch’s System of Geology.

The walls of our venerable fabric may have crumbled into dust ;
the altar may have disappeared from its hallowed site; and the
ministering priests may have been enshrined beneath, while its
pillars, like those of ‘* 'Tadmor in the wilderness,” ‘may re-
main to attest in sullen grandeur that time has spared but its
locality and its name.

Arr. XXIII.—A System of Geology, with a Theory of the
Earth, and an explanation of its connection with the Sacred
Records. By Joun MacCuttocu, M.D., F.R.S., &o. In
two volumes, 8vo. Pp. 512 and 483.

Wer have not for a long time met with a book of more pro-

mise and less fulfilment than the one before us. It has neither :

the merit of strikingly original, though crude views, nor ‘of
sound unostentatious philosophy,—nor of a luminous exposi-
tion of facts,—nor of a happy effort of generalization,—nor of
ability of historic detail,—nor, finally, least of all that it pre-
tends to, of being a “ System” fitted for the use of the students’.
It is also wanting in an eminent degree in that which may re-
commend even an indifferent work to the leniency of the rea-
der,—its being written in a good spirit, and with a candid de-
sire to do justice to those who have pre-occupied the same
field. This very fact is enough to convey unfavourable im-
pressions of the character of the work, which a more careful
scrutiny will not perhaps tend to dispel.

The idea of a “‘ System of Geology” at this day, with.
out frequent and honourable mention of the names and
labours of Cuvier, Brongniart, Humboldt, Von Buch, Sedge-
wick, Buckland, Murchison, Smith, and many others whom
‘we need not attempt to enumerate, seems almost a contra-
diction in terms; and as Dr MacCulloch confines himself
in a great measure to the field of his labours in Scotland,
we aight more particularly have expected to meet with
abundant references to the writings of Saussure, and Boué,
and Jameson, and Hibbert; instead of which we find
these two volumes absolutely innocent (we believe) of foot
notes, without reference to the works, and, with a few rare
exceptions, without mention of the names of these fellow Ja-

MacCulloch’s System of Geology. 359

bourers on the field of geology, which many of them have de«
voted their whole lives to extend and enrich; and it is painful
to add, that in the few instances where such notices do occur,
it is almost without exception, in terms of blame, and never, or
almost hever, in those of praise. Even with the want of this
courtesy, or rather justice which we are entitled to expect, we
might have been disposed to give the work due credit for its
intrinsic merit—for views so great and absorbing as to blot out
for a moment the recollection of the painful labours of immor-
tal minds which had brought the science to such a point of
perfection as to require only a master’s hand to associate and
generalize—or foraplan so compendious and didactic as should .
free the author from the charge of egotism, by the laborious
_and perspicuous selection of facts and views from every acces-
sible source. ‘The work certainly enjoys neither of these cha-
racteristics, and we suspect by this time, though we have seen
no notice of it whatever, has taken its station in the ranks of
literature,—a low one we believe, and above which it will ne-
_ ver rise.
That the System of Geology has some few good points
about it, no impartial person, we believe, will deny ;. whilst
its defects are so obvious and glaring, that men of far less
intellectual stamina than Dr MacCulloch himself, will delight
to tear it in pieces and trample it under foot, whilst few will
ever attempt to separate the valuable grains from the over-
weeningly preponderating mass of chaff. That the Doctor
does not even deprecate criticism is quite obvious from
the whole tone of the work. He has fairly laid himself
open to the most merciless attacks on every hand, and he will
probably experience them. He seems almost to want his usual
self-confidence in recommending his book: And how could it
be otherwise? During by far the greater part of his 995 pages,
the matter is stale; the manner is feeble ; the premises are often
indistinct ; the conclusions are often inconclusive; the matter
is ill arranged, the views sometimes inconsistent or opposed ;* |
the work is ill printed; it is devoid of illustration on wood,
copper, or stone ; and the price is,—L.1, 12s. This, we sus-
- pect, is the key-stone to the whole work; the “‘auri sacra fames”
peeps through at every corner; and the Doctor, we imagine,

“* Compare the Jast chapter with other parts of the work.

860 MacCulloch’s System of Geology.

never counted strata with more assiduity in Argyleshire, * than
he computed the multiples of L. 1, 12s.

We do not propose to enter minutely into the merits or
demerits of the book ; but before making any extracts from it,
we would point out rather a singular consideration | which its
perusal must suggest toa reflecting mind. We had occasion
not long since to notice Mr Lyell’s interesting first volume of
“« Principles of Geology,” as the first attempt in this country
for a long series of years to generalize upon the accumulating

facts of geological science. His second volume is hardly in the
press, when a work by Dr MacCulloch of similar pretensions
appears, only with the more imposing name of a “ System,”
having the same objects, professing the same end, and differ-
ing only in the mode :—but how different! Certainly no two
works on one subject ever appeared with an interval of half a
- dozen of centuries between them, more antipodal than these two
at a distance of as many months. ‘They coincide in few par-
ticular hypotheses,—in many they are utterly opposed; but
what is more extraordinary, they have hardly the title or sub-
ject matter of a chapter common to both. The bewildered
reader, standing with an authority by no means destitute of
weight on each hand, is apt to inquire where truth lies? Whe-
ther the ** System,” or the “ Principles,” contain the essence
of the science; for it is utterly impossible that both can do so.
It is really important to inquire into this anomalous condition
of the science, (for, however triumphant each party may con-
sider his.ewn fundamental principles, and baseless those of his
opponent, anomalous we must still consider it,) and to show
how so important a schism could arise without throwing to the
winds any imagined data which geology has been considered to”
possess.

We are pivgared to concede that Dr MacCulloch possesses
the advantage of a varied acquaintance with the physical
sciences, to which many, or most of his opponents (and we in-
clude Mr Lyell,) lay noclaim. This superiority, for such it
undoubtedly is, may have done Dr MacCulloch more harm than
good asa pure geologist, by the way in which he has employed
it, and the disparagement which he has taken every occasion
to throw upon the attainments of the modern school of geolo-
gists ;—yet it has led him to take some just views (as they ap-

* See the System of Geology, vol. is ps 93.

MacCulloch’s System of Geology. 361

pear to us) of the nature of the science, which have been
wholly overlooked by some other writers, and which has led
to an erroneous view of the qualifications requisite to the geo-
logist, and of the great objects of his science to unfold.

Before geology had acquired * a local habitation and a
name,” the efforts of early speculators were directed, as is well
known, to the wide and uncertain field of pure theory con-
nected with the origin of the globe ; the connection of scrip-
turally historical with physical events, and especially the traces
and effects of the Mosaic deluge. The descriptive portion of
the science was then a blank. It would have been thought
equally beneath the dignity of science to classify rocks and
simple minerals, or to descend into a minute comparison of fos-
sil organic remains with the existing species. Why should
those to whom Nature has revealed hen ample page scrutinize
the particular mode of her operation, which could, they
imagined, add little to the knowledge of general facts or
laws? Why should the phenomena of active causes be ex-
amined, the destructive influence of volcanos and earth-
quakes, or the devastating operations of seas and rivers, when
a comet might as readily be conceived to torrefy the terrestrial
nucleus from pole to pole by the approach of its ignited mass,
by its attraction to change the axis of rotation, and by the
action of a vast tidal wave submerge the mountains, and raise
to light and air the peopled cavities of the ancient ocean? No
dynamical effect was too powerful for such resources, and as
new phenomena arose, new under-plots were added to thedrama -
of creation ; new trains of wheels, no matter how cumbrous,
were added without mercy to the old one, till the hands were
made once more to tell true upon the dial-plate, and permit-
ted to remain till new discoveries rendered new substitutions
necessary :—

how they will wield
‘The mighty frame, how build, unbuild, contrive,
To save appearances.

An advancing state of physical science led men to amend the
laxity which cosmogonal theories had assumed in the days of
Burnet and Whiston, and the speculations of Hutton and
Werner, both of whom gave much weight to facts of observa-
tion, raised a new and very superior class of geologists, What-

,

362 MacCulloch’s System of Geology.

ever may have been the errors of these two theories, which as-
summed the names’of their respective authors, it cannot be de-
nied that, independently of any light they may have indivi-
dually thrown upon the creative processes of nature, their in-
fluence on men’s minds was highly important. The doctrine
of consolidation by heat and pressure, and that of universal
formations, were brought to their respective tests of experiment
and observation ; the former was confirmed as far, perhaps far-
ther, than could have been expected, under factitious cireum-
stances; whilst the other was shown to have originated in its uts
most generality in the narrow views of the ingenious but untra-
velled projector of it; and thus men became habituated to the
wholesome practice of using well their hands and eyes before
they began to speculate upon the subject.

The acrimony which the Huttonian and Wernerian con-
troversy excited, produced a reaction, and geologists resoly-
ed for a time to banish hypotheses and to endeavour to view
nature as she was, untinted by the medium through which
theorists are too willing to view the objects of their research.
his most important stage in the history of geology, and the
true bearings of which have not, we think, been sufficiently -
adverted to, has been so ably sketched in an admirable re-
view of Mr Liyell’s “ Principles” in a contemporary periodi-
cal work, * that we shall make no apology for quoting it.
We have no hesitation in referring for the paternity of the ar-
ticle to the banks of the Cam.

«« Notwithstanding that the labour and industry of our iol
logical observers have been such as men seldom bestow, except
forthe purpose of proving or confirming some favouriteopinion,
their self-denial and temperance in abstaining from theory-mak-
ing have been quite as eminent as their diligence in collecting
materials. ‘To any one acquainted with the recent original pro-
ductions of our geological literature, this must have occurred
as a very curious characteristic. Nothing can be more copious
or communicative than these publications, so far as details are’
concerned. 'To describe, to circumscribe, to subdivide the
strata of particular localities ; to class, distinguish, restore the
animal remains discovered; to identify distant rocks in the
_ Minutest circumstances; these and’ similar subjects have been

* British Critic, Jan. 1831.

MacCulloch’s System of Geology. 363

the theme of many a long and dreary communication which has
been read to the Geological Society, and which it required all the
- ingenuity and good taste of the members to enliven by the
agreeable extempore discussions which succeed the readings.
In most cases the writers described what they saw, and that
was all. Stones were to them as flowers to Peter Bell :

| «A primrose on a river’s brim

A yellow primrose was to him,
And it was nothing more.”

«The case was not asin former days, when the crystals of a
single hand-specimen were supposed capable of revealing the
history of the original condition of the world. No doubt among
all this mass of detail, (most valuable and indispensable, notwith-
standing its tendency to tiresomeness,) there did occur and must
occur suggestions and opinions as to the causes and connexions of
the appearances described. It was the glimmering of dim and
distant truths of this kind, which often gave the subject the
charm of an oriental fiction ; and lured the inquirers onwards,

** O’er bog or steep, through straight, rough, dense, or rare.”

But that which was truly admirable, was the constancy and firm-
-ness with which our geologists abstained from either dwelling
upon such speculations as important, positive, certain, and lead-
ing points in the science; or from considering an assent to any
such opinions as a proof of the orthodoxy and soundness of
geological faith of any of their brethren. There was among
them a strong suspicion of all generalities; an inflexible rejec.
tion of every thing which referred to Mr Jenkinson’s favour-
ite topic of ‘ the cosmogony or creation of the world; and a
resolute determination not to be misled, even by the most tempt,
ing promises of a beautiful and consistent theory, into the
rashness of generalizing from immature and partial observa-
tions.”

The singular discovery of the relation of fossil organic re-
mains to the strata in which they are found, to which. the
beautiful collections of Woodward show that he had so nearly
arrived, was reserved to immortalize the name of Smith. Such
a discovery could not fail to absorb the attention of the embryo
school. of geologists who made the dogged determination, to
observe nature and nature alone; and almost the whole weight

364 -MacCulloch’s System of Geology.

of talent devoted to the rising science was embarked in this
one research. The superposition of rocks, their connection, sub-
divisions, and classification, were all studied by the new light
of fossil remains: the broken shell, or the mammoth’s tusk,
which a. century ago would have been referred to as a proof of
the deluge, (and in saying so it would have been considered
as the sum total of information which the fossils were calculat-
ed to afford,) i is Now regarded merely as an index to mark the
formation in which it is found, as occupying the place of a
given term in a known series of rocks, or rather a series of
synchronous deposits ; and the knowledge thus obtained would
be regarded as amounting merely to the determination of the —
structure of a given spot upon the surface of the globe, with-
out reference to any ulterior or speculative question. No-
thing, therefore, can be more distinct than the character of geo-
logy in the three periods we have sketched; and it is worth _
inquiry whether the science does not admit of a division of -
objects equally distinct. We have had the cosmogonal or ear-
liest period, the middle one, or period of theoretical induction,
from observation and experiment more or less extended, ene
the last, or age of purely descriptive geology.

The course pursued has been precisely the reverse of that
which has obtained in the exact sciences. Men began with
the transcendental and advanced to the rudimentary. The
first geologists elaborated their systems in their closets, the
next race combined the facts of nature in the most philosuphi-
cal manner that their abilities or opportunities permitted, and
deduced theories, legitimately so called ; the last do little more
than collate their note-books,—give a natural historical account
of what they see,—identify their shells and plants with Sowerby
and Brongniart,—and deposit their insulated facts in archives —
which are to be the mines out of which a future and happier
race of philosophers are to draw conclusions and build hypo-
theses. If such be admitted to be a correct picture of the pre-
sent state of geology, we can only congratulate its future cul-
tivators upon having such indefatigable and disinterested pre-
decessors, who are willing themselves to go into eternal obli-
vion, provided the materials they have spent their lives in
quarrying are destined one day to form a portion of a great
and symmetrical edifice. _'This we know to be the view of some

MacCulloch’s System of Geology. 305

of the ablest and most long-sighted of those now engaged in
this gigantic labour. |
If we have succeeded in explaining ourselves, it will be very
elear that we would wish to consider geology as having two
essentially distinct parts, — Descriptive Geology and the Philoso-
phy of Geology. In fact, the mere description of the earth’s
crust is essentially a branch of natural history, whilst the spe-
culation becomes one of physics the moment that the element
of time is introduced, and we begin to investigate the history
and causes of any species of change to which it may. be sub-
ject, whether past or future. ‘This, then, is a clear line of de-
marcation; and the two branches of the science are so neces-
sarily distinct, and require such a very different class of acquire-
ments and habits of thought for their respective prosecution,
that we wonder they should so generally be considered as one
and the same, or as distinguished by a line so purely metaphy-
sical that the one cannot be practically cultivated without the
other. For ourselves, we have no hesitation in considering the
physics of geology as the most interesting and important de-
partment of the science, without any wish to undervalue the
practical labours of those who furnish data to found and to
test speculations. But are we to infer that men wanting the
technical knowledge requisite to the complete natural histori-
cal description of a phenomenon, should be the less able on
that account to deduce correct inferences respecting its causes
and the legitimate conclusions to which it leads? Or is the re-
lation of the mere observer the less to be relied on because he
may be incapable of drawing from it all the inferences it may.
warrant ? We would say, much the reverse.. ‘The theory of
the one and the facts of the other are only the more worthy
of confidence ;_ the one is unable to bend his facts to accommo-
date his theory ; the other has no theory to support. To take
an example: A physical geologist wishes to know the epoch of
elevation of a mountain range ;, and suppose that from the di-
rection of the chain he suspects from hypothesis that it was
elevated at one period rather than another ; he finds one rock
formation lying upon the flanks of the range in a way indica-
tive of having been raised along with it, whilst another is su-
perimposed unconformably in horizontal strata. He is en-
titled to infer from dynamical principles that the epoch he re-

566 MacCulloch’s System of Geology.

quires lies between the date of deposition of these two rocks.
Ignorant of the niceties of discrimination of fossil species, or
possibly, of mineral character, he refers to the descriptive geo-
logist to assign the respective places of the two rocks in the
system, who may perhaps know nothing of the purposes which
this determination is to serve. Is the doctrine of parallelism
of chains of synchronous elevation more or less satisfactorily
determined by the co-operation of these two observers than if
one only had been employed? It were easy to multiply illus-
trations.

Considering the vast multiplicity of sciences, many of theni
burdened with enormous technical labour, which become ne-
cessary to a complete geologist, it were vain to look for such
a “ perfect monster.” Mechanics, dynamics, hydrostatics,
pneumatics, chemistry, mineralogy, botany, zoology, are but a
portion of the encyclopedaical knowledge with which he ought
to be familiar, several of which individually become the labour
of a lifetime fully to master: Hence a certain subdivision of
labour has been successfully resorted to, and even the natural
historical school of geologists often depend for their technical
facts upon the authority of a single individual who has studied
the subject. The momenta doubtful fossil is presented to the
geological society, if it be a bone, it is put into the hands of
Mr Clift; if a shell, Mr Sowerby gives his verdict; if an insect,
Mr Kirby ; if a plant, Mr Brown or Mr Lindley. This is
as it should be; but in the higher divisions of the science a
similar plan should be followed ; the physics of geology should
not be made subordinate to, but distinct from pure natural
history. ‘The ponderous and most elaborate volumes of the
Geological Transactions contain piles of facts, but the spirit in
which they are treated seems to indicate a trivial standard as
the ultimate aim of the geologist. To determine to which
subordinate stratum of a large group a particular rock is to be ~
referred, is often considered a most important question as a
matter of fact, yet it rarely happens that such a determination
is capable of leading to the revelation of a class of general
laws. ‘Though we had a perfect geological map of the globe,
the minds which were engaged in its construction might be
quite incapable of drawing any valuable conclusion from it, —
and in precisely the saine way we might consider the author

MacCulloch’s System of Geology. 367

of the most elaborate paper in the Geological ‘Transactions as
incapable of. writing either the elements or a system of geolo-
gy. He might give lists of characteristic fossils,—he might
teach the mode of observing, collecting, classifying rocks;.-he
might give the whole substance of Conybeare and Phillips's
Geology of England, and yet might prove himself incapable of
enunciating a single general law of the science, of drawing
just geological conclusions, of assigning causes adequate to ef-
fects, or commit errors which the humblest elements of dyna-_
_ mics, hydrostatics, or chemistry would have prevented. _

That many important facts depend upon apparently trivial
determinations of the geological position of individual strata,
we must not be conceived to deny. All we assert is, that such
a determination, per se, is of little imterest to science, and that
much precious time, capable of giving the most important ex-
tension to our knowledge of natural laws; has been ‘spent in
the determination of matters of fact which, the chances are equal,
may never add to the limits of geological science. ‘fo well di-
rected efforts we can set no limits. The physical geologist
must be perpetually indebted to the natural historian for the
determination of facts which the knowledge of the latter will
enable him to answer much more decisively than any moderate
acquisition of the former could be expected to effect. . Yet the
mechanical philosopher is not a closet geologist. His depart-
ment does not, indeed, lead him to map the junction of two
strata with the precision of a surveyor, or to decide with ela-
borate investigation whether a red sandstone be old or new,
or a limestone represent the encrinal series or the coal measures:
—but his walk is by the volcano and the torrent :-—It is he who
ean judge how far causes now in action are competent to the
production of past events. He watches the silent erosion of
the o¢ean-beaten cliffs; his skill computes the slow but sure
transportation of the glaciers. Trained in the school of sober
induction, he passes with philosophic caution from the known
to the questionable ; he traces the analogy of present effects to
past effects, and thence, of present causes to past causes ; he
can seize the differences which science teaches should subsist
between the results of power small in amount prolonged through
time of indefinite extent, and of power indefinitely great actmg
during a short space of time. The mineralogist may compare

NEW SERIES, VOL. V. NO. Il. OCTOBER 1831. Aa

'

368. MacCulloch’s System of Geology.

the volcanic and trap rocks, and pronounce. their. natural-his-,_

torical character identical; but how infinitely more general-and .
conclusive the deductions of the geologist, exercised. by habits
of physical research, in pointing out the real discrepancies of
aqueous and igneous solution, the chemical effects of heaton
rocks, the proofs of mechanical force in elevation, the testimony,
which the now rigid mass can be made to reveal of the direc-
tion and intensity of the effort. : a
Need we touch on the loftier speculations pai pt
geology :—Of the speculations which the figure of. the earth
renders more sure than almost any others to be found. in the
science, which yet, from the want of the requisite knowledge,
few geologists can do any thing but take upon trust :—Need we

allude to Mr Herschel’s inquiries into that portion.of. geologi..

cal dynamics connected with astronomy,—thus. providing a
link between the revolutions of our globe, and those of the sys-
tem of which it forms but a single member? When we.consi-
der the necessary difference, we had almost said. opposition,
which subsists between the pursuits of natural history and those
of experimental philosophy, can we wonder at the want.of tact
in observing, (or rather in treating observations,) the illogical
reasoning; the inadequacy of causes to effects, the arguments
a priori, the bigotry to hypotheses, which so frequently cha-
racterize the writings of mere descriptive geologists; and we
must consider that the science rests on a tottering basis ‘till
some one sufficiently qualified devotes himself to the physies

of the question, and places it on a better footing... But the —

rage for technicalities, which gives the present geological school
its peculiar character, which at little expence of thought occu-
pies the physical and mental energies to a certain extent, and
permits the imagination to run wild in its most fantastic course,
whilst an error in nomenclature is the gravest offence it recog-
nizes,-—so long as this rage continues in its full extent to di-
vert the mind from the whole to part, and to make natural
history the first, second, and third, requisite.to geology, we
can hardly hope that those who might work a revolution, in
the science, will be induced to set their face against the ‘‘ ex-

clusive” habits of the age. But we believe a day, must come
before geology is altogether worthy of the name of a science,
when men, (either in this or some other country,) worthy of

|
|

ee

MacCulloch’s System of Geology. — 869

the names, and inheritors of the talents of Davy; Wollaston,

and Young, may. be equally identified with geology, as the
brightest of those who now y_adorn and HN its prone
department.

That some of the wlodéen school of geologists hinta exbibitetd
acquirements of both kinds in an eminent degree, we should be
the last to deny ; but upon the principle that solid discovery
is most likely to attend the efforts of those who circumscribe
their energies to a narrow track, we believe that the true inte-
rests of science would be better served by some such discrimi-
nation of objects as we have pointed at, than by an attempt°to
grasp at such wide and varied qualifications as belong to -
beau ideal of a perfect geologist. * |

It is easily conceivable, upon the principles now laid ho tem
that two works might be written upon geology, each sufficiently
complete in their respective departments, yet with hardly a
subject incommon. From the scientific school in which he has
been trained, the strongest part of Mr Lyell’s book was, as
might have been expected, what belongs to natural history ;
and we formerly took occasion to express our opinion of the
weakness of the physical department of the book,—an opinion
which has since been amply confirmed in other quarters. But
Dr MacCulloch, with a store of knowledge which well fitted
him for entering upon some parts of this wide field, has shown

* We believe we run little risk of making an invidious comparison by
saying, that perhaps the fittest man in Britain for writing upon geology
at large is Mr Conybeare. His acquirements in the exact sciences and in
general physics, and his stock of knewledge upon the details of geology, to
which he has so largely added; fit him peculiarly for the task ; and we
hope he will be prevailed upon to give to the world a compact system, in-
stead of continuing the detached fragments which for some time appeared
at monthly intervals in the Philosophical Maguzine. We may add, that
in Mr De La Beche’s Geological Manual, which we have only had leisure
to look into since the present article was written, we can perceive, amidst
the superabundance of natural-historical details, a just sense of where the
distinction of physical geology ought to lie. ‘The ‘‘ Sections and Views of
Geological Phenomena” of the same author, are most valuable ; and, as
their name expresses, abound in examples of those inestimable traces which
nature sometimes leaves of her modus operandi,—traces which it should be
the principal object of the physical geologist to discover and ‘investigate,

- and which the mere natural historian may often pass over without.a mo-

ment’s observation. "pot

*
3710 -~MacCulloch’s System of Geology.

a similar mistake in attempting the whole, and in a spirit ill
adapted to soften the ruggedness of the real deformities of the
work. With that propensity we so often see to view that side
of a subject as all-important, of which our previous knowledge
enables us to form a just idea, and to consider every other |
point of view as insignificant, Dr MacCulloch uncompromis-
ingly upholds every tittle of the supremacy of mineral charae-
ter, and with a levity which is quite characteristic of his style,
throws aside, as utterly worthless, the whole theory of fossil
remains, as indicative of the strata. He exalts the primitive
rocks to an unmeasured degree of importance over the secon-
dary and tertiary in the very spirit of Werner, whom, never-
theless, he takes every opportunity to discredit and trample on,
and to whom he bears the farther resemblance of drawing almost
all his illustrations from a country, limited both in absolute
and geological extent,—namely, Scotland. It is not wonderful
that the Doctor should choose this country for the Saxony of his
*‘ System.” There are few countries which ever repaid so well
the labour of geological research, and few observations have
ever been published in such a variety of form as Dr MacCul-
loch’s. It must be unnecessary even to refer to a certain
Parliamentary return upon a “ Mineralogical Survey,” to prove
that modern alchemy has achieved the transmutation*of even
the basest minerals into gold,—that the philosopher’s stone may
be discovered by the adept in rocks of every age :—
“* Tollit humo Saxum ; Saxum quoque palluit auro.
Contigit et glebam ; contactu gleba potenti
Massa fit.” Ov.
With regard to the volumes before us, we have neither space
nor inclination to enter into any analysis of them ; and they pos-
sess few either of the charms of style, the merit of novelty, or
of any other kind, totempt us. The work is, to speak geologi-
cally, a conglomerate ;—not, however, composed of the varied
materials which have so long been added as insulated groups
of facts to the science,—not gleaned with fidelity and judg-
ment from the works of predecessors and contemporaries, and
set in a basis which should at once compact and add lustre to
the whole ; but it is a conglomerate of the triturated and time-
worn fragments of the Doctor’s own works, and the “ basis or

ground” is of the same sombre hue with the morsels which it
;

MacCulloch’s System of Geology. 371

-

encloses. ‘here is hardly one of the thousand pages in which
Dr MacCulloch does not implicitly or explicitly appear; and
the Account of the Western Isles of Scotland, the Classifica-
tion of Rocks, with his scattered papers in the Geological Trans-
actions, (which by the way he never quotes but to mention his
own memoirs, unless in terms of contempt,) down ‘to the very
Description of Hammers in the Appendix, and other glean-
ings from his contribations to periodical works :—these are
the staple commodities of the book, which are now piled toge-
ther with so little arrangement, that the Doctor openly profes-
ses to express different opinions in his second volume from
what are contained in the first; and the very arrangement of
the chapters, (like dislocated strata,) assumes a different con-
figuration in the body of the work, and in the table of con-
tents.

We are at a loss where to quote from: The preface, per-
haps, presents as good an idea of the style and pretensions of
the work, as any part of it. We shall therefore make one or
two brief extracts.

Of all announcements by way of recommendation for a work
ona daily widening science, the following is the strangest we
have met with: ‘“* This work was written in 1821 (!) and it
has therefore slept even beyond the Horatian period.” The
succeeding paragraph throws completely into the shade any-
thing we have attempted to say respecting the neglect of the
physical department of geology. ‘“ I have waited ten years,
in the announced hope that some better man would stand
forward in the breach, the representative of Geological science
as it now is: endeavouring also to tempt others to this peri-
lous honour, by the occasional publication of certain por- ,
tions. I do not see that it has been superseded; nor that
there are any hopes from a longer delay. I did also expect
that time would have brought material improvements, through
the efforts of the present multitude of labourers. I grieve to
say that it has scarcely received a valuable addition from this
source, and not a single fundamental'one. The evidences’ of
Geology have indeed been multiplied; yet through identical
facts only : since I do not perceive that a new one has been ad-

ded to the science. ‘This ought not to have been.”"—Pref. p. v.
The modest author's idea of his work may be gathered from

.
3t2 . MacCulloch’s System of Geology.

the following passages. | ‘* If, to controvert, be termed contro-
versy, I am sorry for what I could not avoid. I neither envy
the taste nor the feelings that delight in this bane of modern
science and literature: under which, they who can contribute
nothing, seek for fame, by depreciating what they even rarely
understand. Never has there been a science, unless it be physic,
so encumbered with rubbish as geology: it was impossible to
move a single step without clearing it away. He who desired
to build on the solid rock of Nature could not but attempt to
remove the ruins that obscured it. And whoever seeks to
‘make his understanding a repository of truth for his own
sake, rather than the warehouse of other men’s false and incon-
clusive reasonings,’ will follow the same plan.

‘‘ Of the arrangement of this work I have little to say. I
have referred to my Classification of Rocks as the grammar of
this science, while avoiding, as much as possible, all collision

between them. If the order, of the subjects does not prove -

satisfactory, I will gladly hear of a better; yet it must be
from one who has bestowed equal thought on an unexception-
able arrangement. If there are repetitions, and if references
to, things not yet examined, I shall be pleased to see any plan
that will remove.this blot from one place, without ib an
equal or worse one somewhere else.”—Pref: p, vii.

‘‘ T am sensible that the sketch of a’ Theory of the Earth re-
quires a volume, instead of a Chapter; and further, that it can
scarcely be understood without that series of drawings, as a

guide through a perfect labyrinth of reflections, without which

I could not even have written it. It must remain for others

to demand such a volume: and if it is not Jess true that illus-

trations would have been most useful to the whole work, as

they had been prepared for it, there are few who do not know

=e the obstruction lies, as it is they alone who. can remove
—Pref. p. vin.

"Thin | is really too bad, in a thirty-two shilling book, without
(as we have already said) even the semblance of a wood-cut, or
illustration of any kind: but we can heartily subscribe to the
assertion, that the ‘Theory of the Earth” is greatly in want
of some such elucidation. Would not the India Compan
100 copies have paid for a few diagrams ?

Take as a specimen of the application of science the fallow

MacCulloch’s System of Geology. 373

ing lecture on hammers: ‘ The hammer of quarrymen is a
double truncated wedge : while nothing but extreme ignorance
of mathematical principles could have extended this form to
those of road-makers and geologists : whence their inefficiency,
even under an inconvenient increase of weight. The fragment, —
in each case, is produced by exciting a vibration in an imaginary
lamina, through a motion too sudden.to be accompanied by
that of. the adjoining parts. It is forgotten that the commu-
nication of motion is not regulated by the momentum, simply,
of the moving body. The weight and the velocity cannot be
indifferently interchanged : and thence strange errors in many
other matters also, of daily practice. But, not to enter further
on this subject, suffice it, that it requires a time inversely pro-
portioned to the tenacity of a body, to allow it to be displaced
in amass; whence, if additional momentum be required, the
weight, not the velocity, must be increased. - But if it is re-
quired to disintegrate the same body, it is the velocity that
must be augmented. It is by impulse that the stone is bro-
ken in the present case. Hence it is useless to increase the
weight of such a hammer, beyond that to which the hand can
give the greatest velocity, since there is thus a loss of power.
I have taken four pounds as the extreme weight ; while two,
or less, will, in a proper form, suffice for most rocks.

But that form depending on the mode in which rocks split,
the whole impulse should fall on as narrow a line as possible.
In practice, however, that cannot be; because the centre of
percussion of a wedge cannot easily be made to impinge verti-
cally on a surface. But the same object is sufficiently attain-
ed by the impulse on a point, through a spheroidal form : as,
in a sphere, it is evident that every direction will be, equally,
and always, fully, effectual. But this being ‘difficult to con-
struct, is also unnecessary, while the oblate spheroidal form is
even better; since the curvature of the equatorial portion al-
lows of a‘ narrower: point of contact, with an equal weight
than a sphere would do: the breadth of that contact diminish-
ing the power, for obvious reasons. "—Vol. 1. pp. 466, 467.

‘The chapter on the “ Relations of Organic Remains” is per-
haps the most extraordinary and intemperate part of the book.
But to do Dr MacCulloch justice, we coincide much in the fol-
lowing views-with which it opens: “ The increase of know-
ledge has given a very different complexion to this subject,

374 MacCulloch’s System of Geology.

and a more rational direction to the pursuit. Yet the geolo-
gist seems in danger of forgetting that it is but one part of his
science. Its details belong to zoology and botany; and he
loses sight of his main object when he pursues these minutize
to the neglect of their more imteresting connections with the
history of the globe. Still more deeply does he err, when he
imagines that a theory of the earth can be founded on what
involves so small a portion of ifs structure and history. It is
doubtless, essential to know these objects; as, to arrange and
name them is the grammar of this department. But it is un-
fortunately true, that whether the contemplation of minutiz
disables the mind for wider views, or that only a minute mind
can be engrossed by such things, the power of profiting by
collections and their study, diminishes in proportion to their
extent and the activity of collectors, whether it be in natural
history or books.

‘ The true business of a geologist, here, is a of a far higher
character. It is to determine the antiquity of these objects
and that of the earths in which they lived, the waters which
they inhabited, and the former places of those; to explain
why they are now imbedded in rocks when once free, why ele-
vated. on the land when once beneath the sea, why they aré
partially distributed, and far more ; as it is also his office to
see how these things explain the history of the earth, If
- found in alluvial soils, other inquiries of an analogous nature
arise, relating especially to the later history of the globe.
And in the study of the objects themselves, if he undertakes
the office of the zoologist and. botanist, it is his business to com-
pare the dead. with the existing races, through which it is his
own. proper office to draw inferences as to the history of the
living creations of the earth, as to that of the earth itself.”—

— Vol. i. PP: 406, 407.

The views of climate in this chapter, (Vol. i. p. 492, &e.),
which. do not.admit of abridgement, are vague and, most unsa-
tisfactory, endeavouring to prove that we have no evidence. of
a change’ of climate. |

Perhaps Professor Sedgewick and Mr Murchison could tell
us something about the following, passage : “<The evidence for
the existence.of orthoceratites abundant in a quarts rock in Su-
therland, which follows gneiss and is connected with it, I consi-
der to be as perfect as we are entitled to expect on sucha subject,

MacCulloch’s System of Geology. 375

from the researches of one individual, under the neglect of all
other observers. In any case, where no previous hypothesis to
the contrary had existed, no one would hesitate in receiving it.
“‘ If a recent geologist has undertaken, in the last case, to ex-
plain otherwise what he never saw, because he preferred an-
cient ignorance to modern truth, (!!) he has algo forgotten that
the secondary and the primary strata never can undergo a joint .
undulation : he could not have been ignorant to this extent,
though his researches had been confined to the recent strata :
it has been the oversight of anxiety for an hypothesis. And
geologists would be better employed in seeking for new truths,
than in determining what is, because they think that it ought
to be. If this is to be the rule, all observation is useless: he
who has seen nothing becomes the interpreter of everything,
and interprets as he had previously statuted to do: Geology
is attained, and we may rest from our labours. But if it is
thus to become a science, it is the first that ever succeeded
through this road. I owe this remark to the geological stu-
dent, (!!) whom I have undertaken to teach in all that I know
myself, and whom it is my duty to guide where he has been
misled.” —Vol. i. pp. 418, 419.

We conclude with Dr MacCulloch’s memorable final para-
graph on “ the identification of strata through organic fossils,”
which we suppose he considers fine writing ; if so, we imagine
he stands alone. ‘ It is quite time that geologists should re-
view their system, in this, as in far more, and correct their
practice. Then, and not till then, shall we begin fairly to »
study the history of the Earth ; and, in time, we shall know
the Truth ; the Truth itself, and the ever odious truth that
we have been in the wrong. Let shells be used as aids, as far
as they can: but if strata are to be determined by shells alone, ~
it will be the land of shells and conchologists that will set the
pattern of the earth, as other lands and other conchologists,
will, under Breislak’s remark; contest for other patterns. ‘This is
not geology ; and thus will Geology never be.”—Vol. 1. p. 454.

We shall not attempt to criticize this extraordinary chapter,
—we leave it in far abler hands,—to those by whom it will be
thoroughly sifted,—to the dissecting knife of the comparative
anatomist, and the tender mercies of the members of the Geo-
logical Society. F.

Te See

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‘

INDEX TO VOL. V.

NEW SERIES.

Achromatic object-glasses for micro-
scopes, on some properties of, 169,
249

Adie, Mr, his meteorological register,
190, 376

Airy, Professor, on the double refraction
of quartz, 324

Analysis of solar light, on a new one,
197

Aurora borealis, on the determination of ~

its position, &c. 23, 209—account of a
remarkable one, 252

Bibliography, contributions to scientific,
219

Blackwall, Mr John, his description of a
a new species of Lamprotornis, 332
Brewster, Dr, on a new analysis of solar
light, 197

Caithness, on the existence of rein-deer
in Orkney, 50

Cairns, on vitrified ones in Orkney, 309

Chevalier, Charles M., reply to Dr Gor-
ing’s critique on his object glasses,

~ 224—-Dr Goring’s remarks on his pa-

per, 238

Cultivators of natural science, observa-
tions on the account of the meeting
at Hamburgh, 271

Decline of science in England, 1, 334

Elsness in Orkney, on the vitrified cairns
at, 310

Euler, M. Leonhard, on the perfection
of microscopes, 233

Fishes of the Ganges, on the respiratory
organs and air-bladders of some of
them, 33

Forbes, Mr J. D. on polar temperature,
&e. 17

Fossil vegetables, on their structure, 183

Geology, Dr MacCulloch’s system of,
reviewed, 358

Goring; Dr, on monochromatic light,
and on the aberration of eye-pieces,
&c. 52—M. Chevalier’s reply to a pa-
per by him, 224—his remarks on M.
Chevalier’s paper, and on Euler’s me-
moir, 238

Heat, on the alleged polarization of, 207

Hibbert, Dr, on rein-deer in Caithness
during the twelfth’century,.50—on the
theories of vitrified forts, 285—on the
vitrified cairns of Orkney, 309

Johnston, Mr J. F. W., on the disco-
very of vanadium in Scotland, 166—
on the vanadiate of lead, a new mine-
ral species, 167—-on Mr Potter's pa-
per on specific heats, 265-Dr Muncke’s
observations on his account of the Ger-
man meeting, 271—Mr Johnston’s re-
ply to those remarks, 278—his noti-
ces regarding vanadium, 318

Laidlaw, Mr, on an aurora borealis,
252°

Lamprotornis, on a new species of, 332

Lister, Mr, on some properties of achro-
matic object-glasses for microscopes,
169, 249

MacCulloch, Dr, his system of geology
reviewed, 358

Metals, on their specific heats, 75, 265

Monochromatic light, observations on its

_ use in microscopes, 52, 143

Muncke, Professor, on Mr Johnston’s ac-
count of the meeting of German natu-
ralists, 271

New York, on the mean temperature of,
34 places in the state of, for 1830,
255

Orkney, on vitrified cairns in, 309

Polarization of heat, 206

Polar temperature considered, 17

Potter, Mr R., on the determination of
the position of the aurorea boreales,
23, 209—on the specific heats of me-
tals, 75

Powell, Rev. B., on the alleged polariza-
tion of heat, 206

Quartz, on the double refraction of, 324

Rein-Deer, on its existence in Shetland
during the 12th century, 50

Rigaud, Proiessor, his account of Mr
James Stirling, 191

Rio, Andres del, on the reduction of sil-
ver ores, 222

Science, on the decline of, in England,
1, 334

~~ ere | ee ae .
Fe ee i ea Pa aide» SA
' : eas

378 : wees a: ISDEX,

Silver ores reduced by the method of Temperature of the Pole, 17 ei
Becquerel, 222 Vanadiate of lead, a new mineral, 167
Solyr light, on a-new analysis of, 197 Vanadium, the new metal di io 4
Specific heats of metals. determined by Scotland, 166—process for obtaining
Mr Potter, Sigs gg on them, it, 318—its properties, 319

265 Vitrified” forts, on the theory of, 285—.
Sterns, round, prize offered respecting cairns in Orkney, 309

‘them, 282 Witham,. Mr, on the microscopic struc-
Stirling, Mr James, some account of, ture of fossil vegetables, 183

191 York, notice of a scientific meeting to be

Taylor, Mr J., on the respiratory organs held me 181
and air-bladder of certain fishes of the.
Ganges, 33 ,

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